LAMINATED GLAZING

The present invention relates to a laminated glazing for use in an automobile, in particular for use as a windscreen in an automobile; to a method of making a laminated glazing; and to use of said laminated glazing.

Conventional laminated glazings for automotive windscreens comprise two plies of soda-lime- silicate glass joined by a sheet of polyvinyl butyral (PVB). Typically, each glass sheet is 2.1mm thick and the PVB sheet is typically 0.76mm thick.

As is known in the art, a laminated automotive windscreen provides the driver of the vehicle with improved safety benefits. However, vehicle manufacturers are also addressing vehicle safety in the event of a forward collision with a pedestrian.

In the event of a collision with a pedestrian, the pedestrian may impact the vehicle windscreen thereby causing further injury to the pedestrian.

W02013181505A1 describes a glass laminate including at least one chemically-strengthened glass sheet with a thickness not exceeding 2.0 mm and a polymer interlayer between the glass sheets. Flaws are created in the surface of one of the glass sheets in order to weaken the glass laminate upon an impact event on a first side of the laminate, while retaining the strength of the laminate upon impact on the opposing second side of the laminate.

EP2062862A1 describes a sheet glass laminate structure produced by laminating at least three sheet glasses each having a thickness of less than 1 mm through an intermediate layer between two adjacent sheet glasses.

WO2019245819A1 describes a glass laminate construction with controlled breakage for pedestrian safety.

The present invention aims to provide a laminated glazing for a vehicle windscreen that is arranged to lower the risks of serious pedestrian injuries in case the vehicle collides with a pedestrian.

Accordingly, from a first aspect the present invention provides a laminated glazing for a vehicle windscreen comprising a first sheet of glass joined to a second sheet of glass by an interlayer structure comprising at least one sheet of adhesive interlayer material, each of the first and second sheets of glass having a respective first major surface and opposing second major surface, the first major surface of the first sheet of glass comprising a first region being aligned with a first region of the second major surface of the first sheet of glass and spaced apart therefrom in a thickness direction of the first sheet of glass by a first distance .s' in microns (pm), and the first major surface of the second sheet of glass comprising a first region being aligned with a first region of the second major surface of the second sheet of glass and spaced apart therefrom in a thickness direction of the second sheet of glass by a second distance t in microns (gm), wherein the first region of the second major surface of the second sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the second major surface of the second sheet of glass having a depth d in the thickness direction of the second sheet of glass, wherein d in microns (pm) is at D x t least - , wherein D is between 0. 1 and 0.3.

Lasers are known to laser mark glass and lasers are commercially available for laser marking glass.

It is known in the art that laser marking is a method that uses a laser to alter the surface of a target made of a particular material to “mark” the surface of the target. For certain target materials, the laser mark may be due to a change of colour of the surface of the target after being irradiated by the laser. In the art, laser marking that includes the removal of material from a surface may be referred to as laser engraving or laser etching. Laser engraving typically provides a deeper mark compared to laser etching.

Without being bound by theory, it is well known that when a sheet of glass cools, for example from a temperature above the softening point of the glass to ambient temperature i.e. about 25°C, the surface of the sheet of glass develops a compressive stress layer and the central region of the sheet of glass develops a tension stress layer. The compressive stress layer extends from a major surface of the cooled sheet of glass and the magnitude of the compressive stress decreases in a thickness direction of the sheet of glass until the central tension stress layer is reached. For uniform cooling, the compressive stress layer has uniform thickness from each major surface of the uniformly cooled sheet of glass. According to the present invention, by providing a region of the second major surface of the second sheet of glass with at least one

D x t laser mark having depth in microns of at least where D is between 0. 1 and 0.3 and t is the thickness of the sheet of glass in microns, the thickness of the compressive stress layer of the second sheet of glass is reduced by the first laser mark in the region of the first laser mark. This adjusts how the second sheet of glass breaks following an impact with the laminated glazing.

The first laser mark on the first region of the second major surface of the second sheet of glass is produced by directing a suitable laser having sufficient power for a sufficient length of time towards the second major surface of the second sheet of glass to produce the first laser mark.

Within the context of the present invention, the first laser mark causes damage in the body of the glass between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass.

The depth of the first laser mark may be determined by taking a cross-section through the second sheet of glass.

The depth of the first laser mark may be determined using a microscope, which may be an optical microscope or a scanning electron microscope, to examine the cross-section through the second sheet of glass. The depth of the first laser mark may include a depth of a cavity and/or a depth of a region of damage in between the first region of the first major surface of the second sheet of glass and the first region of the second major surface of the second sheet of glass caused by the first laser mark being formed on the first region of the second major surface of the glass sheet. When the first laser mark comprises a cavity, the depth of the first laser mark may be determined using a suitable profiling sensor such as a stylus or confocal displacement sensor.

Preferably the first laser mark on the first region of the second major surface of the second sheet of comprises an opening in the first region of the second major surface of the second sheet of glass.

Preferably D is equal to 0.1.

Preferably D is equal to 0.2.

Preferably D is equal to 0.3.

Preferably d in microns is less than where w is 25, or where w is 20, w is 15, w is 10, or where w is 5, or where w is 4, or where w is 3, or where w is 2, or where w is 1.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass has a depth d greater than 5 pm.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass has a depth d less than 50pm.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass comprises at least one line and/or at least one dot.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass is in the form of a geometric shape. Preferably the geometric shape is circular, oval or an ellipse. Preferably the geometric shape has an outer periphery having two, or three, or four, our five, or six, or seven, or eight, or nine, or ten sides. Preferably the geometric shape is in the form of a rectangle, diamond, parallelogram or square.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass has at least three sides.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass comprises an outline of a geometric shape.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass comprises an outline of a geometric shape and inboard the outline the first laser mark on the first region of the second major surface of the second sheet of glass or, when present, the opening in the first region of the second major surface of the second sheet of glass, comprises one or more laser marked regions.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass has an outer edge parallel to, or substantially parallel to, at least a portion of an outer edge of the second sheet of glass.

Preferably the first region of the second major surface of the second sheet of glass comprises two or more laser marks thereon.

Preferably laminated glazing is arranged such that the second major surface of the first sheet of glass faces the first major surface of the second sheet of glass.

Preferably the laminated glazing is arranged such that the second major surface of the first sheet of glass faces the second major surface of the second sheet of glass.

Preferably the first sheet of glass is an outer ply of the laminated glazing and the second sheet of glass is an inner ply of the laminated glazing.

Preferably the first major surface of the first sheet of glass is surface one of the laminated glazing.

Embodiments wherein the first laser mark on the first region of the second major surface of the second sheet of glass comprises an opening in the first region of the second major surface of the second sheet of glass have other preferable features.

Preferably the opening in the first region of the second major surface of the second sheet of glass is in the form of a geometric shape. Preferably the geometric shape is circular, oval or an ellipse. Preferably the geometric shape has an outer periphery having two, or three, or four, our five, or six, or seven, or eight, or nine, or ten sides. Preferably the geometric shape is in the form of a rectangle, diamond, parallelogram or square.

Preferably the opening in the first region of the second major surface of the second sheet of glass has at least three sides.

Preferably the opening in the first region of the second major surface of the second sheet of glass comprises an outline of a geometric shape.

Preferably the opening in the first region of the second major surface of the second sheet of glass comprises an outline of a geometric shape and inboard the outline the first laser mark on the first region of the second major surface of the second sheet of glass or the opening in the first region of the second major surface of the second sheet of glass comprises one or more laser marked regions. Preferably the opening in the first region of the second major surface of the second sheet of glass has an outer edge parallel to, or substantially parallel to, at least a portion of an outer edge of the second sheet of glass.

Preferably the opening in the first region of the second major surface of the second sheet of glass comprises a curved portion and/or a linear portion.

Preferably in plan-view, the opening in the first region of the second major surface of the second sheet of glass is circular, oval, triangular, square, rectangular, has at least three sides, one of which may be curved; or is irregularly shaped.

In some embodiments the first region of the first major surface of the second sheet of glass has a different composition to the first region of the second major surface of the second sheet of glass. This may conveniently be achieved by coating the first region of the second major surface of the second sheet of glass.

In some embodiments the first region of the second major surface of the second sheet of glass has a coating thereon, the coating having a thickness and the thickness of the coating contributes to the second distance t. For example, if the second sheet of glass has a thickness of T microns, and the coating has thickness of C microns, then t = T + C.

The coating preferably has a thickness C between 1 pm and 100 pm.

In such embodiments, the depth d may be greater than or equal to the thickness of the coating C. In these embodiments the first laser mark on the first region of the second major surface of the second sheet of glass extends through the coating to reach the underlying second sheet of glass.

In such embodiments, the depth d may be less than the thickness of the coating C. In these embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is in the coating that is on the first region of the second major surface of the second sheet of glass.

In some embodiments where the first region of the second major surface of the second sheet of glass has a coating thereon, the coating is optically opaque at one or more wavelength in the wavelength range 380nm to 780nm. The coating is optically opaque if the transmittance at normal incidence through the coated first region of the second sheet of glass at the one or more wavelength is less than 10%, preferably less than 5%.

In some embodiments wherein the first region of the second major surface of the second sheet of glass has a coating thereon, preferably the coating is fused to the second major surface of the second sheet of glass.

In some embodiments where the first region of the second major surface of the second sheet of glass has a coating thereon, the coating is derived from a frit. Preferably the frit is a type of frit used to provide an automotive glazing with an obscuration band.

Preferably the coating is a screen printed coating derived from a screen printed material. Screen printing glass sheets is well known in the art, in particular for applying obscuration bands to vehicle glazings.

Preferably the screen printed material has a composition comprising from about 35 to about 75 weight percent frit, from about 5 to about 40 weight percent of a pigment, from zero to about 25 weight percent of a crystal seed powder, and from about 10 to about 40 weight percent of a printing medium. More preferably, the screen printed material comprises from about 40 to about 60 weight percent frit, from about 10 to about 35 weight percent of a pigment, from zero to about 25 weight percent of a crystal seed powder, from zero to about 10 weight percent of a metal and/or a metal oxide, and from about 15 to about 40 weight of a percent printing medium.

When the frit comprises a glass frit, the frit of the screen printed material may comprise lead- containing frit and/or lead-free frit.

Preferably the frit comprises a glass frit and/or a ceramic frit.

As used herein, the term "glass frit" means pre-fused glass material which is typically produced by rapid solidification of molten material followed by grinding or milling to a desired powder size. Preferred glass frits may comprise from 0 to about 75 weight percent lead oxide, from 0 to about 75 weight percent bismuth oxide, from 0 to about 75 weight percent silica, from 0 to about 50 weight percent zinc oxide, from 0 to about 40 weight percent boron oxide, from 0 to about 15 weight percent aluminium oxide, from 0 to about 15 weight percent zirconium oxide, from 0 to about 8 weight percent titanium oxide, from 0 to about 20 weight percent phosphorous oxide, from 0 to about 15 weight percent calcium oxide, from 0 to about 10 weight percent manganese oxide, from 0 to about 7 weight percent copper oxide, from 0 to about 5 weight percent cobalt oxide, from 0 to about 15 weight percent iron oxide, from 0 to about 20 weight percent sodium oxide, from 0 to about 20 weight percent potassium oxide, from 0 to about 15 weight percent lithium oxide and from 0 to about 7 weight percent fluoride, as well as other oxides conventionally used in glass frit compositions.

The pigment of the screen printed material may comprise inorganic pigments such as spinels, zircons, rutiles, garnets, haematites, ultramarines and the like may also be used as the marking component. In addition to inorganic pigments, precursors thereof are useful in forming high quality marks. For example, a light green coloured mixture of titanium dioxide, antimony trioxide and chrome oxide, which is the precursor to Cr-Sb-Ti buff, may be used.

The crystal seed powder of the screen printed material may comprise, for example, bismuth silicate, zinc silicate and/or zinc borate.

Metal oxides include cobalt oxide, copper oxide, iron oxide and praseodymium oxide. Suitable metal includes metal powders such as iron, copper, nickel, silver, chromium, and the like.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass has an area that is less than 10% of the area of the second major surface of the second sheet of glass. It is preferred to keep the area of the first laser mark on the first region of the second major surface of the second sheet of glass as small as possible to not affect vision through the laminated glazing.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass has an area that is less than 5%, or 4%, or 3%, or 2%, or 1% of the area of the second major surface of the second sheet of glass.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on the second major surface of the second sheet of glass, and the total area of the plurality of laser marks on the second major surface of the second sheet of glass is preferably less than 10%, or 9%, or 8%, or 7%, or 6%, or 5%, or 4%, or 3%, or 2%, or 1% of the area of the second major surface of the second sheet of glass.

In some embodiments first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on the second major surface of the second sheet of glass and the area of the first laser mark on the first region of the second major surface of the second sheet of glass is between 0.01cm ² and 200cm ² , preferably between 0.01cm ² and 100cm ² , more preferably between 0.01cm ² and 10cm ² , even more preferably between 0.01cm ² and 5cm ² , even more preferably between 0.01cm ² and 0.5cm ² .

Preferably one or more of the other laser marks in the plurality of laser marks on the second major surface of the second sheet of glass has an area between 0.01cm ² and 200cm ² , preferably between 0.01cm ² and 100cm ² , more preferably between 0.01cm ² and 10cm ² , even more preferably between 0.01cm ² and 5cm ² , even more preferably between 0.01cm ² and 0.5cm ² .

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on the first region of the second major surface of the second sheet of glass, and wherein two or more of the laser marks on the first region of the second major surface of the second sheet of glass have the same area.

Preferably all of the laser marks in the plurality of laser marks on the first region of the second major surface of the second sheet of glass have the same area.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is spaced apart from a second laser mark on the second major surface of the second sheet of glass by a first spacing, wherein the first spacing is between 0.5cm and 50cm, more preferably between 0.5cm and 40cm, more preferably between 0.5cm and 30cm, more preferably between 0.5cm and 20cm, more preferably between 0.5cm and 10cm. The first spacing may be defined in relation to the geometric centres of the first and second laser marks.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is spaced apart from a peripheral edge of the laminated glazing.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass is spaced apart from the peripheral edge of the laminated glazing by between 1cm and 20cm, more preferably between 1cm and 15cm, more preferably between 1cm and 10cm, more preferably between 1cm and 9cm or 8cm or 7cm or 6cm or 5cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is spaced apart from a peripheral edge of the laminated glazing configured to be a lower edge of the laminated glazing when installed in a vehicle.

Preferably the first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on second major surface of the second sheet of glass spaced apart from the peripheral edge of the laminated glazing configured to be the lower edge of the laminated glazing when installed in a vehicle.

Preferably the laser marks in the plurality of laser marks on the second major surface of the second sheet of glass spaced apart from the peripheral edge of the laminated glazing configured to be the lower edge of the laminated glazing when installed in a vehicle are arranged in a line, and preferably the line is parallel to the peripheral edge of the laminated glazing configured to be the lower edge of the laminated glazing when installed in a vehicle.

When the first laser mark on the first region of the second major surface of the second sheet of glass is one region of a plurality of laser marks on the second major surface of the sheet of glass, it is preferred that each laser mark has an area that is the same to within +20%.

When the first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on the second major surface of the sheet of glass, it is preferred that each laser mark has the same area.

When the first laser mark on the first region of the second major surface of the second sheet of glass is one of a plurality of laser marks on the second major surface of the sheet of glass, it is preferred that each laser mark has the same depth.

In some embodiments the first sheet of glass has a thickness between 1mm and 5mm, preferably between 1.3mm and 3mm

In some embodiments the second sheet of glass has a thickness between 1mm and 5mm, preferably between 1.3mm and 3mm. In some embodiments the second sheet of glass is thinner than the first sheet of glass.

In some embodiments the first major surface of the first sheet of glass is a convex surface and the second major surface of the second sheet of glass is a convex surface.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at a wavelength between 300nm and L pm, wherein L is 0.5, or 1, or 1.5, or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11, or 15. For example, preferably the laser is operable at a wavelength between 300nm and 1.5pm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using at least one of an excimer laser, an ultra-violet laser, a carbon dioxide laser, a neodymiunrYAG laser and a neodymium: yttrium orthovanadate (YVCfi) laser.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz at least 8pm or at least 9pm or at least 10pm, and preferably with Rz at most 20pm or preferably with Rz at most 19 pm. As is known to a person skilled in the art, Rz is the maximum height of the profile and is the sum of the largest profile peak height and the largest profile valley depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 0.5 pm to 5 pm. Ra is the arithmetical mean deviation of the profile within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 10 pm and/or preferably having Rmax at most 25 pm. Rmax is the largest single roughness depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm. In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rv being at least 4 pm, preferably at least 5 pm and/or preferably with Rv at most 20 pm, more preferably at most 19 pm, even more preferably at most 15 pm. Rv is the maximum profile valley depth (Rv) within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz less than about 8 pm, and preferably with Rz at least 1 pm or Rz at least 1.5 pm or Rz at least 2 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 0.3 pm to 2 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 1 pm and/or preferably having Rmax at most 10 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rv being at most 4 pm, preferably at most 3 pm and/or preferably with Rv being at least 0.5 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm. In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz at least 8pm or at least 9pm or at least 10pm, and preferably with Rz at most 40pm or preferably with Rz at most 35 pm or more preferably with Rz at most 30 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 2 pm to 8 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass adjusts the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 20 pm and/or preferably having Rmax at most 50 pm or preferably with Rmax at most 40 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a CO2 laser to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz at least 8pm or at least 9pm or at least 10pm, and preferably with Rz at most 20pm or preferably with Rz at most 19 pm. As is known to a person skilled in the art, Rz is the maximum height of the profile and is the sum of the largest profile peak height and the largest profile valley depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a CO2 laser to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 0.5 pm to 5 pm. Ra is the arithmetical mean deviation of the profile within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm. In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a CO2 laser to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 10 pm and/or preferably having Rmax at most 25 pm. Rmax is the largest single roughness depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a CO2 laser to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rv being at least 4 pm, preferably at least 5 pm and/or preferably with Rv at most 20 pm, more preferably at most 19 pm, even more preferably at most 15 pm. Rv is the maximum profile valley depth (Rv) within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at about 1064nm, preferably a neodymium :YAG laser or a neodymium :yttrium orthovanadate (YVO4) laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz less than about 8pm, and preferably with Rz at least 1 pm or Rz at least 1.5 pm or Rz at least 2 pm. As is known to a person skilled in the art, Rz is the maximum height of the profile and is the sum of the largest profile peak height and the largest profile valley depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at about 1064nm, preferably a neodymium :YAG laser or a neodymium :yttrium orthovanadate (YVO4) laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 0.3 pm to 2 pm. Ra is the arithmetical mean deviation of the profile within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at about 1064nm, preferably a neodymium :YAG laser or a neodymium :yttrium orthovanadate (YVO4) laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 1 pm and/or preferably having Rmax at most 10 pm. Rmax is the largest single roughness depth within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at about 1064nm, preferably a neodymium :YAG laser or a neodymium :yttrium orthovanadate (YVO4) laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rv being at most 4 pm, preferably at most 3 pm and/or preferably with Rv being at least 0.5 pm. Rv is the maximum profile valley depth (Rv) within a sampling length. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at a wavelength between about lOOnm and 380nm, preferably an excimer laser or an ultra-violet laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rz at least 8pm or at least 9pm or at least 10pm, and preferably with Rz at most 40pm or preferably with Rz at most 35 pm or more preferably with Rz at most 30 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at a wavelength between about lOOnm and 380nm, preferably an excimer laser or an ultra-violet laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Ra in the range of 2 pm to 8 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at a wavelength between about lOOnm and 380nm, preferably an excimer laser or an ultra-violet laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rmax being at least 20 pm and/or preferably having Rmax at most 50 pm or preferably with Rmax at most 40 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass is made using a laser operable at a wavelength between about lOOnm and 380nm, preferably an excimer laser or an ultra-violet laser, to adjust the roughness of the second major surface of the second sheet of glass such that the first laser mark on the first region of the second major surface of the second sheet of glass comprises a portion having a surface roughness with Rv being at least 4 pm, preferably at least 5 pm and/or preferably with Rv at most 20 pm, more preferably at most 19 pm, even more preferably at most 15 pm. The sample length may be less than 5cm, preferably between 0.5cm and 4cm, or 0.5cm and 3cm, or 0.5cm and 2cm, or 0.5cm and 1cm. The sample length may be greater or equal to 1cm.

In some embodiments, the laminated glazing is arranged such that the second major surface of the first sheet of glass faces the first major surface of the second sheet of glass, or wherein the laminated glazing is arranged such that the second major surface of the first sheet of glass faces the second major surface of the second sheet of glass, and following an impact with a suitable impactor at an impact location on the first major surface of the first sheet of glass, the laminated glazing develops cracks in the vicinity of the impact location in less than 2ms.

In such embodiments, the laminated glazing fully breaks within 2ms, preferably 1ms of the time taken for the cracks to develop.

Preferably the impactor is as described in UN Regulation No. 127 (E/ECE/324/Rev.2/Add. 126/Rev.2).

Preferably the impactor has a mass between 3kg and 6kg, more preferably between 4kg and 5kg, even more preferably a mass of 4.5kg.

Preferably the impactor is a sphere or a spheroid and preferably has a diameter between 15cm and 20cm, more preferably between 16 and 17cm.

Preferably when the impactor strikes the impact location, the velocity thereof is between 20km/h and 50km/h, more preferably between 35km/h and 45km/h, even more preferably 40km/h.

Preferably the impactor impacts the impact location by falling under gravity alone.

In such embodiments, preferably the first major surface of the first sheet of glass is surface one of the laminated glazing. As is conventional in the art, surface one of a laminated glazing is an outermost surface of the laminated glazing and surface four of the laminated glazing is an inner facing surface being defined in relation to a vehicle interior in which the laminated glazing is installed. The inner facing surface of the laminated glazing faces the interior of the vehicle in which the laminated glazing is installed. The outermost surface (often referred to as the outer surface) faces the exterior of the vehicle in which the laminated glazing is installed.

The laminated glazing according to the first aspect of the present invention has other preferable features.

Preferably the first region of the first major surface of the second sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the first major surface of the second sheet of glass having a depth e in the thickness direction of the second sheet of glass, wherein e in microns is at least X t

- , wherein E is between 0. 1 and 0.3.

Preferably the first region of the first major surface of the second sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the first major surface of the second sheet of glass comprising an opening in the first region of the first major surface of the second sheet of glass and a X t depth e in the thickness direction of the second sheet of glass, wherein e in microns is at least wherein E is between 0.1 and 0.3.

Preferably the first region of the first major surface of the first sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the first major surface of the first sheet of glass having a depth /in the thickness direction of the first sheet of glass, wherein in microns is at least wherein F is between 0. 1 and 0.3.

Preferably the first region of the first major surface of the first sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the first major surface of the first sheet of glass comprising an opening in the first region of the first major surface of the first sheet of glass and a depth /in the thickness direction of the first sheet of glass, wherein /in microns is at least wherein F is between 0.1 and 0.3.

Preferably the first region of the second major surface of the first sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the second major surface of the first sheet of glass having a depth g in the thickness direction of the first sheet of glass, wherein g in microns is at least G s - , wherein G is between 0. 1 and 0.3.

Preferably the first region of the second major surface of the first sheet of glass has at least a first laser mark thereon, the first laser mark on the first region of the second major surface of the first sheet of glass comprising an opening in the first region of the second major surface of the first sheet of glass and a G s depth g in the thickness direction of the first sheet of glass, wherein g in microns is at least wherein G is between 0.1 and 0.3.

Preferably the laminated glazing is a vehicle windscreen. Preferably the laminated glazing is curved in at least one direction. Preferably the radius of curvature in the at least one direction is between 500mm and 20000mm, more preferably between 1000mm and 8000mm.

Preferably the first major surface of the first sheet of glass is convex.

Preferably the second major surface of the second sheet of glass is concave or convex.

Preferably the at least one sheet of adhesive interlayer material comprises polyvinyl butyral (PVB), acoustic modified PVB, a copolymer of ethylene such as ethylene vinyl acetate (EVA), polyurethane (PU), poly vinyl chloride (PVC), a copolymer of ethylene and methacrylic acid (EMA) or Uvekol (a liquid curable resin).

Preferably the at least one sheet of adhesive interlayer material is a sheet of polyvinyl butyral (PVB), EVA, PVC, EMA, polyurethane, acoustic modified PVB or Uvekol (a liquid curable resin).

Preferably the at least one sheet of adhesive interlayer material has a thickness between 0.3mm and 2.3mm, more preferably between 0.3mm and 1.6mm, most preferably between 0.3 and 0.8mm.

Preferably the interlayer structure comprises at least one sheet of polyester, more preferably at least one sheet of polyethylene terephthalate (PET), and preferably the at least one sheet of polyester carries on at least one major surface thereof an optically transparent coating that reflects infrared radiation.

Preferably the first and/or second sheet of glass has a thickness between 1mm and 3mm.

Preferably the first and/or second sheet of glass has a thickness between 1.4mm and 2.8mm, more preferably between 1.6mm and 2.3mm.

Preferably the first sheet of glass is a sheet of soda-lime-silicate glass, in particular a sheet of float glass.

Preferably the second sheet of glass is a sheet of soda-lime-silicate glass, in particular a sheet of float glass.

Preferably the first and/or second sheet of glass is made using a float process. Other methods of making sheet glass may also be used, such as rolling and down drawing.

Soda-lime-silicate glass is often referred to as soda-lime-silica glass, or simply a sheet “soda-lime” glass.

Preferably the first and second sheets of glass are not chemically strengthened. A sheet of glass may be classified as not being chemically strengthened when the sheet of glass has not been subject to an ion exchange process or has been subject to an ion exchange process following which the depth of layer is between 0 pm and Dx pm, where Dx is 1, or 2, or 3, or 4, or 5. In some embodiments the second sheet of glass is a sheet of alkali aluminosilicate glass.

Preferably the second sheet of alkali aluminosilicate glass comprises at least about 6wt% (percent by weight) aluminium oxide (AI2O3).

In some embodiments the second sheet of glass is chemically strengthened i.e. chemically strengthened glass. When the second sheet of glazing material is chemically strengthened, preferably the second sheet of glass has a thickness less than 1.2mm, more preferably between 0.3mm and 1mm, even more preferably between 0.4mm and 0.9mm.

In some embodiments the first laser mark on the first region of the second major surface of the second sheet of glass comprises a cavity and the depth of the first laser mark on the first region of the second major surface of the second sheet of glass comprises a depth of the cavity, the depth of the cavity extending in the thickness direction of the second sheet of glass from the first region of the second major surface of the second sheet of glass toward the first region of the first major surface of the second sheet of glass.

Preferably the depth of the cavity is a maximum depth of the cavity or an average depth of the cavity.

In some embodiments, the first laser mark on the first region of the second major surface of the second sheet of glass comprises a region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass.

Preferably the region of damage comprises one or more crack

The region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass has a depth.

Preferably the depth of the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass corresponds to the depth of the first laser mark on the first region of the second major surface of the second sheet of glass.

Preferably the depth of the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass contributes to the depth of the first laser mark on the first region of the second major surface of the second sheet of glass.

Preferably the depth of the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass is the same as the depth of the first laser mark on the first region of the second major surface of the second sheet of glass. In embodiments where the first laser mark on the first region of the second major surface of the second sheet of glass does not comprise an opening in the first region of the second major surface of the second sheet of glass, the depth of the first laser mark on the first region of the second major surface of the second sheet of glass is defined in relation to a depth of a region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass, preferably a region of crack damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass.

In such embodiments the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass has a depth and the depth of the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass corresponds to the depth of the first laser mark on the first region of the second major surface of the second sheet of glass.

In embodiments having a region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass, especially a region of crack damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass, the depth of the region of damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass may be defined as the maximum distance in the thickness direction of the second sheet of glass from the first region of the second major surface of the second sheet of glass to a boundary defining the region of crack damage between the first region of the second major surface of the second sheet of glass and the first region of the first major surface of the second sheet of glass. Between the boundary and the first region of the first major surface of the second sheet of glass a portion of the second sheet of glass is essentially damage free, preferably crack free.

Other embodiments of the first aspect of the present invention have other preferable features.

Embodiments where the laminated glazing also has a first laser mark on the first region of the first major surface of the second sheet of glass, the first laser mark on the first region of the first major surface of the second sheet of glass having a depth e in the thickness direction of the second sheet of glass, wherein X t e in microns is at least - 100 and E is between 0. 1 and 0.3 have other p ¹ referable features.

Preferably the first laser mark on the first region of the first major surface of the second sheet of glass comprises an opening in the first region of the first major surface of the second sheet of glass.

Preferably E is 0. 1 or 0.2 or 0.3.

Preferably E is the same as D. Preferably the first laser mark on the first region of the first major surface of the second sheet of glass has the same preferred features as the first laser mark on the first region of the second major surface of the second sheet of glass.

Preferably the first laser mark on the first region of the first major surface of the second sheet of glass was made using the same laser marking process to produce the first laser mark on the first region of the second major surface of the second sheet of glass.

Embodiments where the laminated glazing also has a first laser mark on the first region of the first major surface of the first sheet of glass, the first laser mark on the first region of the first major surface of the first sheet of glass having a depth /in the thickness direction of the first sheet of glass, wherein /in p- x f microns is at least - , and F is between 0.1 and 0.3 have other preferable features.

Preferably first laser mark on the first region of the first major surface of the first sheet of glass comprises an opening in the first region of the first major surface of the first sheet of glass.

Preferably F is 0.1 or 0.2 or 0.3.

Preferably F is the same as D.

Preferably the first laser mark on the first region of the first major surface of the first sheet of glass has the same preferred features as the first laser mark on the first region of the second major surface of the second sheet of glass.

Preferably the first laser mark on the first region of the first major surface of the first sheet of glass was made using the same laser marking process to produce the first laser mark on the first region of the second major surface of the second sheet of glass.

Embodiments where the laminated glazing also has a first laser mark on the first region of the second major surface of the first sheet of glass, the first laser mark on the first region of the second major surface of the first sheet of glass having a depth g in the thickness direction of the first sheet of glass, G s wherein g in microns is at least and wherein G is between 0. 1 and 0.3 have other preferable features.

Preferably first laser mark on the first region of the second major surface of the first sheet of glass comprises an opening in the first region of the second major surface of the first sheet of glass.

Preferably G is 0.1 or 0.2 or 0.3.

Preferably G is the same as D.

Preferably the first laser mark on the first region of the second major surface of the first sheet of glass has the same preferred features as the first laser mark on the first region of the second major surface of the second sheet of glass. Preferably the first laser mark on the first region of the second major surface of the first sheet of glass was made using the same laser marking process to produce the first laser mark on the first region of the second major surface of the second sheet of glass.

Embodiments where the laminated glazing also has a first laser mark on the first region of the first major surface of the first sheet of glass, the first laser mark on the first region of the first major surface of the first sheet of glass having a depth /in the thickness direction of the first sheet of glass, wherein /in p- x f microns is at least - , and F is between 0. 1 and 0.3; and a first laser mark on the first region of the second major surface of the first sheet of glass, the first laser mark on the first region of the second major surface of the first sheet of glass having a depth g in the thickness direction of the first sheet of glass, wherein g in

G s microns is at least - 100 and G is between 0.1 and 0.3 have other p ¹ referable features.

Preferably the first laser mark on the first region of the first major surface of the first sheet of glass comprises an opening in the first region of the first major surface of the first sheet of glass. Preferably F is the same as G.

Preferably F is the same as D.

Preferably G is the same as D.

The present invention also provides from a second aspect a method of making a laminated glazing comprising: (i) a step of providing a first sheet of glass having a first thickness .s' (in microns), the first sheet of glass having a first major surface and a second opposing major surface; (ii) a step of providing a second sheet of glass having a second thickness t (in microns), the second sheet of glass having a first major surface and a second opposing major surface; (iii) a laser marking step comprising using a laser to make a first laser mark on the second major surface of the second sheet of glass, the first laser mark having a depth

D x t in a thickness direction of the second sheet of glass, the depth d in microns being at least wherein D is between 0. 1 and 0.3; and (iv) a lamination step comprising laminating the first sheet of glass to the second sheet of glass using an interlayer structure comprising at least one sheet of adhesive interlayer material such that following the lamination step the first sheet of glass is joined to the second sheet of glass by the interlayer structure.

It has been found that when a laminated glazing is made according to the second aspect of the present invention, the laser marking step (iii) makes the laminated glazing easier to break following an impact towards an exposed surface of the laminated glazing compared to a laminated glazing made without the laser marking step (iii) because the second sheet of glass has been weakened due to the provision of the first laser mark on the second major surface of the second sheet of glass.

During the laser marking step (iii), the first laser mark on the second major surface of the second sheet of glass is produced by directing a suitable laser operating at a suitable wavelength having sufficient power for a sufficient length of time towards the second major surface of the second sheet of glass to produce the first laser mark.

Preferably the first laser mark on the second major surface of the second sheet of glass comprises an opening in the second major surface of the second sheet of glass after the completion of the laser marking step (iii).

Preferably the laser is operable at a wavelength greater than lOOnm.

Preferably the laser is operable at a wavelength less than 20pm.

Preferably the laser is an excimer laser.

Preferably the laser is an ultra-violet laser.

Preferably the laser is a carbon dioxide laser.

Preferably the laser is a neodymiunrYAG laser or a neodymiunryttrium orthovanadate (YVO4) laser.

Preferably the laser is operable at a wavelength between 300nm and L pm, wherein L is 0.5, or 1, or 1.5, or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11, or 15. For example, preferably the laser is operable at a wavelength between 300nm and 1.5pm.

Preferably the laser is operable at between about 300nm and 380nm.

Preferably the laser is operable at about 1064nm.

Preferably the laser is operable at about 9.3pm.

Preferably the laser is operable at about 10.6pm.

Preferably the laser is focussed to a spot size having a maximum external dimension less than 1mm. If the spot is circular, the maximum external dimension is the diameter of the spot.

Preferably during the laser marking step (iii), a laser beam is directed across the second major surface of the second sheet of glass to produce the first laser mark.

Preferably the laser is a continuous laser or a pulsed laser.

Preferably the first laser mark has a depth d greater than 5 pm.

Preferably the first laser mark has a depth d less than where w is 25.

Preferably the first laser mark has a depth d less than 50pm. Preferably the laser mark comprises at least one line and/or at least one dot. The line may be straight or curved and/or the line may be a continuous line.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass comprises a line having a length between 0.5cm and 5cm, more preferably between 1cm and 3cm.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass comprises a line having a width between 10 pm and K pm, where K is 100, or 200, or 300, or 400, or 500, or 1000.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass is in the form of a geometric shape. Preferably the geometric shape is circular. Preferably the geometric shape has an outer periphery having two, or three, or four, our five, or six, or seven, or eight, or nine, or ten sides. Preferably the geometric shape is in the form of a rectangle, diamond, parallelogram or square.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass has at least three sides.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass comprises an outline of a geometric shape.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass comprises an outline of a geometric shape and inboard the outline the first laser mark or the opening in the second major surface of the second sheet of glass comprises one or more laser marks.

Preferably the first laser mark or the opening in the second major surface of the second sheet of glass has an outer edge parallel to, or substantially parallel to, at least a portion of an outer edge of the second sheet of glass.

Preferably the method comprises a further laser marking step, the further laser marking step comprising using a laser to make a first laser mark on at least one of the first major surface of the second sheet of glass, the first major surface of the first sheet of glass and the second major surface of the first sheet of glass.

Preferably the first major surface of the first sheet of glass is convex.

Preferably the second major surface of the second sheet of glass is concave or convex.

Preferably the laminated glazing is curved in at least one direction. Preferably the radius of curvature in the at least one direction is between 500mm and 20000mm, more preferably between 1000mm and 8000mm. Preferably the first sheet of adhesive interlayer material comprises polyvinyl butyral (PVB), acoustic modified PVB, a copolymer of ethylene, such as ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), ethyl methyl acrylate (EMA) copolymer, polyurethane, in particular a thermoplastic polyurethane (TPU), or Uvekol (a liquid curable resin).

Preferably the interlayer structure comprises 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or more, sheets of adhesive interlayer material. Each sheet of adhesive interlayer material may be the same type i.e. all PVB and may all have the same thickness.

Preferably the first sheet of adhesive interlayer material has a thickness between 0.3mm and 2.3mm, more preferably between 0.3mm and 1.6mm, most preferably between 0.3 and 0.8mm.

Preferably the interlayer structure comprises at least one sheet of polyester, more preferably as least one sheet of polyethylene terephthalate (PET), and preferably the at least one sheet of polyester carries on at least one major surface thereof an optically transparent coating that reflects infrared radiation.

As is conventional in the art, surface one of a laminated glazing is an outermost surface of the laminated glazing and surface four of the laminated glazing is an inner facing surface being defined in relation to a vehicle interior in which the laminated glazing is installed.

Preferably the first major surface of the first sheet of glass is surface one of the laminated glazing.

In some embodiments the method comprises a coating step, the coating step taking place before the laser marking step (iii), wherein the coating step comprises coating at least a first region of the second major surface of the second sheet of glass with a coating, there being a first region of the first major surface of the second sheet of glass aligned with the first region of the first major surface of the second sheet of glass.

In such embodiments, the laser marking step (iii) preferably makes the first laser mark in the coating.

Preferably following coating step, the coating has a thickness between 1pm and 100pm.

Preferably during the laser marking step (iii), the laser removes at least a portion of the coating on the first region of the second major surface of the second sheet of glass. The removal of at least a portion of the coating on the first region of the second major surface of the second sheet of glass creates a void or cavity in the coating on the first region of the second major surface of the second sheet.

Preferably during the laser marking step (iii), the laser removes a portion of the coating on the first region of the second major surface of the second sheet of glass that extends through a thickness of the coating preferably to expose the second major surface of the first sheet of glass or to extend into the second sheet of glass. Preferably the coating on the first region of the first major surface of the first sheet of glass is laser marked inboard of the lower peripheral edge of the vehicle windscreen preferably by between j cm and k cm from the lower peripheral edge of the laminated glazing, wherein j= , or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10 and k = 5, or 10, or 15, or 20, or 25, or 25, with the proviso that k > j.

In embodiments comprising a coating step to coat at least a first region of the second major surface of the second sheet of glass, and wherein the laser marking step (iii) removes at least a portion of the coating on the first region of the second major surface of the second sheet of glass to create a void or cavity in the coating on the first region of the second major surface of the second sheet, the void or cavity preferably has an opening such that the first laser mark comprises an opening in the coating on the first region of the second major surface of the second sheet.

In some embodiments that include a coating step, the coating is optically opaque at one or more wavelength in the wavelength range 380nm to 780nm. The coating is optically opaque if the transmittance at normal incidence through the coated first region of the second sheet of glass at the one or more wavelength is less than 10%, preferably less than 5%.

In some embodiments including a coating step, the coating comprises a frit.

Preferably the frit is a type of frit used to provide an automotive glazing with an obscuration band.

Preferably during the coating step, the frit is applied to the first portion of the second major surface of the first sheet of glass using a screen printing process. Screen printing processes are well known in the art.

Preferably the screen printed material has a composition comprising from about 35 to about 75 weight percent frit, from about 5 to about 40 weight percent of a pigment, from zero to about 25 weight percent of a crystal seed powder, and from about 10 to about 40 weight percent of a printing medium. More preferably, the screen printed material comprises from about 40 to about 60 weight percent frit, from about 10 to about 35 weight percent of a pigment, from zero to about 25 weight percent of a crystal seed powder, from zero to about 10 weight percent of a metal and/or a metal oxide, and from about 15 to about 40 weight of a percent printing medium.

When the frit comprises a glass frit, the frit of the screen printed material may comprise lead- containing frit and/or lead-free frit.

Preferably the frit comprises a glass frit and/or a ceramic frit.

As used herein, the term "glass frit" means pre-fused glass material which is typically produced by rapid solidification of molten material followed by grinding or milling to a desired powder size. Preferred glass frits may comprise from 0 to about 75 weight percent lead oxide, from 0 to about 75 weight percent bismuth oxide, from 0 to about 75 weight percent silica, from 0 to about 50 weight percent zinc oxide, from 0 to about 40 weight percent boron oxide, from 0 to about 15 weight percent aluminium oxide, from 0 to about 15 weight percent zirconium oxide, from 0 to about 8 weight percent titanium oxide, from 0 to about 20 weight percent phosphorous oxide, from 0 to about 15 weight percent calcium oxide, from 0 to about 10 weight percent manganese oxide, from 0 to about 7 weight percent copper oxide, from 0 to about 5 weight percent cobalt oxide, from 0 to about 15 weight percent iron oxide, from 0 to about 20 weight percent sodium oxide, from 0 to about 20 weight percent potassium oxide, from 0 to about 15 weight percent lithium oxide and from 0 to about 7 weight percent fluoride, as well as other oxides conventionally used in glass frit compositions.

The pigment of the screen printed material may comprise inorganic pigments such as spinels, zircons, rutiles, garnets, haematites, ultramarines, and the like may also be used as the marking component. In addition to inorganic pigments, precursors thereof are useful in forming high quality marks. For example, a light green coloured mixture of titanium dioxide, antimony trioxide and chrome oxide, which is the precursor to Cr-Sb-Ti buff, may be used.

The crystal seed powder of the screen printed material may comprise, for example, bismuth silicate, zinc silicate and/or zinc borate.

Metal oxides include cobalt oxide, copper oxide, iron oxide and praseodymium oxide.

Suitable metal includes metal powders such as iron, copper, nickel, silver, chromium, and the like.

In some embodiments during the laser marking step (iii), the first laser mark is made in the form of a pattern. Preferably the pattern includes at least a void in a coating on the first region of the first major surface of the first sheet of glass where some of the coating has been removed by the laser marking step (iii). The void in the coating may extend through a thickness of the coating to the glass surface underneath or only part way through the thickness of the coating.

Preferably the pattern comprises a line, which may be straight or curved.

Preferably the pattern comprises at least one of a square, a rectangle, a triangle, a trapezium, a circle, and an ellipse.

Preferably the pattern comprises a shape having an outline. Preferably inboard of the outline the coating has been processed.

Preferably the pattern is in the form of a bar code or a Quick Response (QR) code.

In some embodiments, the method comprises a heating step before the laser marking step (iii), wherein the heating step comprises heating the first and/or second sheet of glass to a temperature suitable for shaping thereof. In embodiments comprising a coating step before the laser marking step (iii), preferably the method comprises a heating step after the coating step and before the laser marking step (iii).

Preferably the heating step comprises heating the second sheet of glass to a suitably high temperature such that the coating adheres to and/or fuses to the first portion of the second major surface of the second sheet of glass. Such embodiments are particularly useful when the coating comprises a frit.

In such embodiments the heating step preferably comprises a shaping step, wherein prior to the shaping step the first and/or second sheet of glass has a first shape, and following the shaping step, the first and/or second sheet of glass has a second shape, the first shape being different to the second shape and the second shape preferably being curved in one or more direction. In such embodiments, it is preferred that prior to the shaping step, the first and/or second sheet of glass is flat, or substantially flat.

Preferably the shaping step takes place after the heating step, but the heating step and the shaping step may overlap in time such that the first sheet of glass is heated during the shaping step.

When the heating step comprises a shaping step, the second sheet of glass sheet is heated to a temperature to be shapeable during the shaping step. Preferably the second sheet of glass is heated to a temperature between 580°C and 680°C.

Preferably the shaping step comprises supporting the second sheet of glass on a shaping member.

Preferably the shaping step comprises shaping the first and/or second sheet of glass by sagging under gravity and/or pressing between a pair of shaping members having complementary shaping surfaces.

Preferably following the shaping step the first sheet of glass is shaped such that the first major surface of the first sheet of glass is a convex surface.

Preferably following the shaping step the second sheet of glass is shaped such that the second major surface of the second sheet of glass is a concave surface or a convex surface.

Preferably the second sheet of glass is bent at the same time as the first sheet of glass. In such embodiments, the first sheet of glass and the second sheet of glass are preferably a nested pair.

In some embodiments the first sheet of glass has a thickness between 1mm and 3mm, preferably between 1.4mm and 2.8mm, more preferably between 1.6mm and 2.3mm.

In some embodiments the first and/or second sheet of glass comprises a sheet of soda-lime-silicate glass. Soda-lime-silicate glass is often referred to as soda-lime-silica glass, or simply a sheet “soda-lime” glass.

In some embodiments the first and/or second sheet of glass comprises a sheet of alkali aluminosilicate glass. In some embodiments the first and/or second sheet of glass comprises at least about 6wt% (percent by weight) aluminium oxide (AI2O3).

In some embodiments the first and/or second sheet of glass is chemically strengthened i.e. chemically strengthened glass. Preferably chemical strengthening includes a chemical strengthening step that takes place before the lamination step (iv).

When the first and/or second sheet of glass is chemically strengthened, preferably the thickness thereof is less than 1.2mm, more preferably between 0.3mm and 1mm, even more preferably between 0.4mm and 0.9mm.

In some embodiments, following the lamination step (iv), the laminated glazing is configured such that the second major surface of the first sheet of glass faces the first major surface of the second sheet of glass.

In such embodiments, preferably the laser marking step (iii) occurs after the lamination step (iv).

In some embodiments the laser marking step (iii) is performed a plurality of times to produce a plurality of laser marks, each laser mark in the plurality of laser marks having a respective depth in a thickness direction of the second sheet of glass.

Preferably at least two of the plurality of laser marks comprise a respective cavity having a respective opening in the second major surface of the second sheet of glass.

Preferably the at least two laser marks each comprise a respective cavity each having the same depth in a thickness direction of the second sheet of glass.

In some embodiments the laser marking step (iii) occurs before the lamination step (iv), and wherein following the lamination step (iv) the laminated glazing is configured such that the second major surface of the first sheet of glass faces the second major surface of the second sheet of glass.

In such embodiments, when the first laser mark on the second major surface of the second sheet of glass comprises an opening in the second major surface of the second sheet of glass, preferably during the lamination step (iv), a portion of the at least one sheet of adhesive interlayer material flows into the opening of the first laser mark on the second major surface of the second sheet of glass.

Other embodiments of the second aspect of the present invention have other preferable features.

Preferably following the lamination step (iv), the laminated glazing is configured such that the second major surface of the second sheet of glass faces the second major surface of the first sheet of glass.

Preferably the first major surface of the first sheet of glass is a convex surface and the second major surface of the second sheet of glass is a concave surface. In some embodiment following an impact with a suitable impactor at an impact location on the first major surface of the first sheet of glass, the laminated glazing develops cracks in the vicinity of the impact location in less than 2ms.

In such embodiments, the laminated glazing fully breaks preferably within 2ms, more preferably 1ms of the time taken for the cracks to develop.

Preferably the impactor is as described in UN Regulation No. 127 (E/ECE/324/Rev.2/Add. 126/Rev.2).

Preferably the impactor has a mass between 3kg and 6kg, more preferably between 4kg and 5kg, even more preferably a mass of 4.5kg.

Preferably the impactor is a sphere or a spheroid and preferably has a diameter between 15cm and 20cm, more preferably between 16 and 17cm.

Preferably when the impactor strikes the impact location, the velocity thereof is between 20km/h and 50km/h, more preferably between 35km/h and 45km/h, even more preferably 40km/h.

Preferably the impactor impacts the impact location by falling under gravity alone.

Preferably the time taken for the laminated glazing to break upon being impacted by the impactor is at least 50%, or 60%, or 70% or 80% shorter than the time taken for the laminated glazing to break without the laminated glazing having a first sheet of glass that has been processed in accordance with the present invention.

The present invention also provides from a third aspect use of one or more laser marks on at least a first major surface of a first sheet of glass included in a laminated glazing, the laminated glazing comprising the first sheet of glass laminated to a second sheet of glass by an interlayer structure comprising at least one sheet of adhesive interlayer material, the one or more laser marks on the first major surface of the first sheet of glass including at least a first laser mark to reduce the time taken for the laminated glazing to break upon being impacted by a suitable impactor at an impact region on an exposed surface of the laminated glazing, wherein at least the first laser mark on the first major surface of the first sheet of glass has a depth d in

D x t microns at least - , wherein D is between 0. 1 and 0.3 and wherein t is the thickness of the first sheet of glass in microns.

Preferably the first laser mark on the first major surface of the first sheet of glass comprises an opening in the first major surface of the first sheet of glass.

Preferably D is 0.1 or 0.2 or 0.3. Preferably d in microns is less than where w is 25, or where w is 20, or where w is 15, or where w is 10, or where w is 5, or where w is 4, or where w is 3, or where w is 2, or where w is 1.

Preferably d is less than 50 pm, or less than 49 gm.

Preferably the first laser mark has a depth d greater than 5 pm.

Preferably the one or more laser marks are on surface three or surface four of the laminated glazing, and the exposed surface is surface one of the laminated glazing.

Preferably the one or more laser marks are on the exposed surface.

Preferably the exposed surface is surface one or surface four of the laminated glazing.

Preferably the one or more laser marks are on at least one of surface one, surface two, surface three or surface four of the laminated glazing

Preferably the one or more laser marks are on surface one or surface two of the laminated glazing, and the exposed surface is surface one of the laminated glazing.

Preferably the one or more laser marks are on surface one or surface two of the laminated glazing, and the exposed surface is surface four of the laminated glazing.

Preferably the one or more laser marks are on surface three or surface four of the laminated glazing, and the exposed surface is surface one or surface four of the laminated glazing.

As is conventional in the art, surface one of a laminated glazing is an outermost surface of the laminated glazing and surface four of the laminated glazing is an inner facing surface being defined in relation to a vehicle interior in which the laminated glazing is installed. The inner facing surface of the laminated glazing faces the interior of the vehicle in which the laminated glazing is installed. The outermost surface (often referred to as the outer surface) faces the exterior of the vehicle in which the laminated glazing is installed.

Preferably the impactor is as described in UN Regulation No. 127 (E/ECE/324/Rev.2/Add. 126/Rev.2).

Preferably the impactor has a mass between 3kg and 6kg, more preferably between 4kg and 5kg, even more preferably a mass of 4.5kg.

Preferably the impactor is a sphere or a spheroid and preferably has a diameter between 15cm and 20cm, more preferably between 16 and 17cm.

Preferably when the impactor strikes the impact location, the velocity thereof is between 20km/h and 50km/h, more preferably between 35km/h and 45km/h, even more preferably 40km/h. Preferably the impactor impacts the impact location by falling under gravity alone.

Preferably the time taken for the laminated glazing to break upon being impacted by the impactor is at least 50%, or 60%, or 70% or 80% shorter than the time taken for the laminated glazing to break without the laminated glazing having the one or more laser mark on the first surface of the sheet of glass.

The present invention will now be described with reference to the following figures (not to scale) in which:

Figure 1 is a cross-sectional view of a laminated glazing in accordance with the present invention;

Figure 2 is a plan-view of a laminated glazing in accordance with the present invention;

Figure 3 is a plan-view of a lower portion of another laminated glazing in accordance with the present invention;

Figure 4 is a schematic isometric representation of a portion of an exposed major surface of the laminated glazing shown in figure 3;

Figure 5 is a cross-sectional view along the line n-n ’ of figure 3;

Figure 6 is a plan-view of a lower portion of another laminated glazing in accordance with the present invention;

Figure 7 is a schematic isometric representation of a portion of an exposed major surface of the laminated glazing shown in figure 6;

Figure 8 is a cross-sectional view of another laminated glazing in accordance with the present invention;

Figure 9 is a cross-sectional view of another laminated glazing in accordance with the present invention;

Figure 10 is a cross-sectional view of another laminated glazing in accordance with the present invention;

Figure 11 is a schematic isometric representation of an uncoated glass sheet having a laser mark thereon;

Figure 12 is a cross-sectional view along the line X-X’ of the uncoated glass sheet shown in figure 11;

Figure 13 is a cross-sectional view of a curved uncoated glass sheet having a laser mark thereon;

Figure 14 is the view from inside a vehicle that has a windscreen in accordance with the present invention; and

Figure 15 is a schematic cross-sectional representation of a method to test the breakage properties of a vehicle windscreen of the type shown in figure 2. Figure 1 shows a cross-sectional view of a curved laminated glazing in accordance with the present invention.

The laminated glazing 1 has a first sheet 3 of soda-lime-silicate glass having a composition such as clear float glass and may include colouring agents such as iron oxide to provide the laminated glazing with some form of solar control. The first sheet 3 has a thickness of 2. 1mm although the thickness may be in the range 1.4mm to 2.5mm or in the range 1.6mm to 2.3mm.

A typical soda-lime-silicate glass composition is (by weight), SiO ₂ 69 - 74 %; AI2O3 0 - 3 %; Na ₂ O 10 - 16 %; K ₂ O 0 - 5 %; MgO 0 - 6 %; CaO 5 - 14 %; SO3 0 - 2 %; Fe ₂ O ₃ 0.005 - 2 %. The glass composition may also contain other additives, for example, refining aids, which would normally be present in an amount of up to 2 %. The soda-lime-silica glass composition may contain other colouring agents such as CO3O4, NiO and Se to impart to the glass a desired colour when viewed in transmitted light. The transmitted glass colour may be measured in terms of a recognised standard such as BS EN410.

The laminated glazing 1 also has a second sheet 7 of soda-lime-silicate glass having a thickness of 2.1mm, but the second sheet may have a thickness may be in the range 1.4mm to 2.5mm and is preferably not as thick as the first sheet 3.

The first sheet 3 is joined to the second sheet 7 by an adhesive interlayer structure 5. The adhesive interlayer structure 5 in this example is a 0.76mm thick sheet of PVB. The adhesive interlayer 5 may have a thickness between 0.3mm and 1.8mm.

Other suitable adhesive interlayers include PVC, EVA, EMA and polyurethane. The interlayer structure 5 may comprise two or more sheets of adhesive interlayer material.

The laminated glazing 1 is curved in one or more directions. The radius of curvature in one of the one or more directions is between 1000mm and 8000mm.

When the laminated glazing is curved in two directions, suitably each direction of curvature is orthogonal to the other. Suitably the radius of curvature in one or both directions of curvature is between 1000mm and 8000mm.

The first sheet 3 has a convex first major surface 9 and an opposing concave second major surface 11. The second sheet 7 has a convex first major surface 13 and an opposing concave second major surface 15. The concave surface 11 of the first sheet 3 is in contact with the adhesive interlayer 5 and the convex surface 13 of the second sheet 7 is in contact with the adhesive interlayer 5. Using conventional nomenclature, the convex major surface 9 of the first sheet 3 is “surface one” (or S 1) of the laminated glazing 1, the concave major surface 11 of first sheet 3 is “surface two” (or S2) of the laminated glazing 1, the convex major surface 13 of second sheet 7 is “surface three” (or S3) of the laminated glazing 1 and the concave major surface 15 of second sheet 7 is “surface four” (or S4) of the laminated glazing 1. There is an array of laser marks 17 on surface four (the concave major surface 15 of the second sheet 7 of soda-lime-silicate glass).

Figure 2 is a schematic plan-view of the laminated glazing 1 in the direction of arrow 10 of figure 1.

In figure 2, the periphery of the laminated glazing is typical of a vehicle windscreen. The laminated glazing has a lower peripheral edge 19 and inboard of the lower peripheral edge 19 are nine laser marks 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i that form the array of laser marks 17. The laser marks 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i are formed in the second major surface 15 by laser marking the surface with a suitable laser i.e. by ablation.

Each laser mark 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i is a square with 2cm sides such that the area of each laser mark 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i is 4cm ² .

The laser marked 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i are equally spaced such that the space between laser marks 17a and 17b is the same as the space between laser marks 17b and 17c, and so on. In this example the space between the centres of the laser marked squares 17a and 17b is about 150mm but may be less than 250mm or more than 50mm.

The laser marks 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i lie in a line that is parallel to, or substantially parallel to, the lower peripheral edge 19.

In this example an obscuration band 21 is on the concave major surface 15 of the second sheet 7. The obscuration band is optically opaque and was applied to the glass in a conventional manner prior to the second sheet 7 being shaped. The obscuration band 21 is a coating that was screen printed onto the glass surface and is fused onto the glass surface by heating.

Inboard of the obscuration band 21 the laminated glazing 1 has a through vision region 23. In the art, the allowable light transmission of a vehicle windscreen is usually set by legislation. In this example, the through vision region exhibits a total visible light transmittance (Illuminant A, two degree observer) of 70% or more as measured at normal incidence.

By providing the laser marks 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i, in the event of an impact on the convex first major surface 9 of the first sheet 3, the second sheet 7 can break more easily so that the rigidity of the laminated glazing 1 is reduced. When the laminated glazing 1 is installed as a windscreen in a vehicle, in the event of a pedestrian being involved in a collision with the vehicle, the reduction in rigidity of the windscreen upon an impact with the convex first surface 9 reduces the seriousness of injury to the pedestrian.

The laser marks 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i are positioned not to be visually distracting to the driver of the vehicle and do not prevent the windscreen 1 from passing stone impact tests. Although figures 1 and 2 have nine laser marks, there may be more than nine laser marks or less than nine laser marks.

Each laser mark 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i was produced in the same way by directing a suitable laser towards the concave major surface 15 and ablating the surface to produce the desired shape laser mark. In this example, the laser was directed towards the obscuration band 21 in the lower region of the laminated glazing.

In the laminated glazing 1, each laser mark is a square and this was produced by moving the incident laser beam relative to the concave major surface 15 in a raster fashion. With reference to the laser mark 17a, the square may be produced by an array of laser ablated parallel lines. Alternatively, the laser mark 17a may be produced by first ablating the concave surface 15 with a first array of lines, which may be parallel, and then using a second pass of the laser to ablate the concave surface 15 with a second array of lines, which may be parallel, and which may be orthogonal to the first array of lines i.e. in the form of a grid.

In one series of tests (“First Tests”, see Table 2 hereinafter), a CO2 laser was used to produce the squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i. The CO2 laser was operable at a wavelength of 10.6pm and at a power suitable to ablate the glass surface, and/or the surface of the obscuration band. The CO2 laser was used to produce the nine squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i each having a size of 2cm by 2cm. The target depth of the laser marked squares was the same and the measured depth of all the laser marked squares was 20-25pm.

Using a suitable profiling sensor such as a stylus or confocal displacement sensor, roughness parameters of the nine squares made using the CO2 laser may be determined. The use of a confocal displacement sensor to evaluate surface profile parameters is described in “Procedia Materials Science, 5 (2014) p. 1385 - 1391”.

Using a Hommel Tester T500 Profilometer available from Hommelwerke GmbH, Alte Tuttlinger StraBe 20, D-78056 VS-Schwenningen, Germany, it was found that the surface roughness of the nine laser marks (squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i) was adjusted compared to the unprocessed surface of the obscuration band.

In this example, the nine squares made using the CO2 laser had Rz between 10 pm and 20 pm. As is known to a person skilled in the art, Rz is the maximum height of the profile and is the sum of the largest profile peak height and the largest profile valley depth within a sampling length.

Another parameter often used to define the roughness of a surface is the arithmetical mean deviation of the profile within a sampling length (usually abbreviated as Ra in the art). It was found the nine squares made using the CO2 laser had an Ra in region of 1.5 pm to 3.1 pm. Other parameters to define surface roughness may be used, for example the largest single roughness depth (Rmax) within a sampling length or the maximum profile valley depth (Rv) within a sampling length. The nine squares made using the CO2 laser had an Rmax in the range 15 pm to 25 pm and an Rv in the range 5 pm to 15 pm.

In another series of tests (“Third Tests”, see table 2 hereinafter), a neodymium: yttrium orthovanadate (YV04) laser operating at a wavelength of 1064nm was used to produce the squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i. The neodymium YV04 laser was operable at a power suitable to ablate the glass surface, and/or the surface of the obscuration band. The neodymium YV04 laser was used to produce the nine squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i each having a size of 2cm by 2cm. The target depth of the squares was the same and the measured depth of all the squares was 1 l-15pm (average about 13 pm).

Using a suitable profiling sensor such as a stylus or confocal displacement sensor, roughness parameters of the nine squares made using the neodymium YV04 laser may be determined.

Using a Hommel Tester T500 Profilometer available from Hommelwerke GmbH, Alte Tuttlinger StraBe 20, D-78056 VS-Schwenningen, Germany, it was found that the surface roughness of the nine laser marks (squares 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i) was adjusted compared to the unprocessed surface of the obscuration band.

In this example, the nine squares made using the neodymium YV04 laser had Rz between 2 pm and 5 pm.

It was found the nine squares made using the neodymium YV04 laser had an Ra in region of 0.4 pm to 0.8 pm.

The nine squares made using the neodymium YV04 laser had an Rmax in the range 2 pm to 5 pm and an Rv in the range 1 pm to 2 pm.

In an alternative embodiment to that shown in figures 1 and 2, the laser marks are produced on the convex major surface 13 of the second sheet 7, which may or may not have an obscuration band thereon. In such an embodiment, the laser marks are made on the second sheet 7 prior to lamination. It is expected similar behaviour would be obtained compared to laser marking the concave major surface 15.

In another alternative embodiment to that shown in figures 1 and 2, the laser marks are produced on the concave major surface 11 of the first sheet 3, which may or may not have an obscuration band thereon. In such an embodiment, the laser marks are made on the first sheet 3 prior to lamination.

In another alternative embodiment to that shown in figures 1 and 2, the laser marks are produced on the convex major surface 9 of the first sheet 3, which may or may not have an obscuration band thereon.

Another embodiment of the present invention is shown in figure 3. Figure 3 shows the lower portion of another laminated glazing 31 that has the same cross-sectional view as the laminated glazing 1 shown in figure 1 and essentially the same plan-view as shown in figure 2.

In a similar way as for the laminated glazing 1, the laminated glazing 31 has an obscuration band 32 extending around the periphery of the exposed major surface 15. Inboard of the obscuration band 32 is a through vision region 33. The laminated glazing 31 has a lower peripheral edge 35.

In this example, there are nine laser marks 37a, 37b, 37c, 37d, 37e, 37f, 37g, 37h, 37i in the obscuration band 32. The laser marks 37a, 37b, 37c, 37d, 37e, 37f, 37g, 37h, 37i are each in the form of lines about 2cm long and are spaced in a parallel relation with the lower peripheral edge 35. The lines are evenly spaced apart from each other by about 10cm. The lines may have different lengths and may be differently spaced apart, for example non-uniformly.

With particular reference to figure 4, there is shown a schematic isometric representation of a portion of the major surface 15 of the laminated glazing 31 showing in more detail the laser mark 37b. The laser mark 37b comprises an elongate cavity 38b having an elongate opening 39b in the surface of the obscuration band 32. The elongate cavity 38b has a length 40b and a width 41b. The cavity has a depth 42b to define the depth of the laser mark 37b.

Also shown in figure 4 is the obscuration band has a thickness 32’ . The depth 42b of the cavity 38b is less than the thickness 32’ of the obscuration band 32 so the laser mark 37b does not extend to the underlying glass sheet 7. This is further illustrated in figure 5 which is a schematic cross-sectional view along the long n-ri’ of figure 3.

As shown in figure 5, the laminated glazing 31 comprises a first sheet of glass 3 joined to a second sheet of glass 7 by a sheet of PVB 5. The second sheet of glass has a thickness 7’ and the cavity 38b in the thickness direction of the second sheet of glass 7 has a depth 42b.

The cross-sectional view shown in figure 5 is normal to a plane making tangential contact with the surface of the obscuration band 32 at a point where the laser mark 37b is to be produced. Accordingly, and with additional reference to figure 1, the cross-section shown in figure 5 is normal a plane making tangential contact with the surface 9 of the first sheet of glass 3, the tangential contact being aligned with the laser mark 37b.

The other laser marks 37a, 37c, 37d, 37e, 37f, 37g, 37h, 37i each comprise a respective cavity having a respective depth.

In another series of tests (“Second Tests”, see table 2 hereinafter), the laser marks 37a, 37b, 37c, 37d, 37e, 37f, 37g, 37h, 37i were produced with a CO2 laser operable at 10.6pm. Each laser mark was about 2cm in length and had a line width of about 0.25mm, essentially determined by the laser beam diameter. Each laser mark was produced by moving the laser beam relative to the laminated glazing and each laser mark had a depth between 10-15 pm. The laser marks may be made deeper by more than a single pass, or by using a higher power, or by using a slower scan speed, or by combinations of these.

In another series of tests (“Fourth Tests”, see table 2 hereinafter), the laser marks 37a, 37b, 37c, 37d, 37e, 37f, 37g, 37h, 37i were produced with a neodymium YVO4 laser operable at 1064nm. Each laser mark was about 2cm in length and had a line width of about 90pm, essentially determined by the laser beam diameter. Each laser mark was produced by moving the laser beam relative to the laminated glazing and each laser mark had a depth between 8-10 pm. The laser marks may be made deeper by more than a single pass, or by using a higher power, or by using a slower scan speed, or by combinations of these.

In an alternative embodiment to that shown with reference to figures 1, 3, 4 and 5, laser marks are made in or on the surface 13 before the first sheet of glass 3 is laminated to the second sheet of glass 7 by the sheet of PVB 5. The surface 13 may or may not have an obscuration band thereon. The laser marks in major surface 13 may be in addition to, or instead of, any or all of the laser marks 37a - 37i .

In another alternative embodiment to that shown with reference to figures 1, 3, 4 and 5, there is no obscuration band 32 so the laser marks 37a - 37i are made in or on the major surface 15 of the second sheet of glass 7.

Figure 6 shows the lower portion of another laminated glazing 51 that has the same cross-sectional view as the laminated glazing 1 shown in figure 1 and essentially the same plan-view as shown in figure 2.

In a similar way as for the laminated glazing 1, the laminated glazing 51 has an obscuration band 52 extending around the periphery of the exposed surface major surface 15. Inboard of the obscuration band 52 is a through vision region 53. The laminated glazing 51 has a lower peripheral edge 55.

In this example, there are nine laser marks 57a, 57b, 57c, 57d, 57e, 57f, 57g, 57h, 57i in the obscuration band 52. The laser marks 57a, 57b, 57c, 57d, 57e, 57f, 57g, 57h, 57i are each in the form of outline squares about 2cm by 2cm in size and in a spaced parallel relation with the lower peripheral edge 55. The outline squares are evenly spaced apart from each other by about 10-15cm.

The laser marks 57a, 57b, 57c, 57d, 57e, 57f, 57g, 57h, 57i may have different outline shape, for example, circles, diamonds, triangles, or irregular shapes.

With particular reference to figure 7, there is shown a schematic isometric representation of a portion of the major surface 15 of the laminated glazing 51 showing in more detail the laser mark 57a.

The laser mark 57a comprises an outline square shaped cavity 58a having an opening 59a in the surface of the obscuration band 52. The cavity 58a has a portion of obscuration band 52a that was not ablated when the outline square cavity 58a was formed. The portion of obscuration band 52a is spaced apart from the periphery of the cavity 58a, to form the outline square shape. If the portion of obscuration band 52a is also ablated by the laser, a square laser mark as shown in figure 2 is formed i.e. essentially laser mark 17a.

Also shown in figure 7 is the obscuration band has a thickness 52’. The depth of the cavity 58a is less than the thickness 52’ of the obscuration band 52, but the cavity may extend into the underlying second sheet of glass 7 i.e. into the soda-lime-silicate glass. The sheet of glass 7 may have a different glass composition.

In another series of tests (“Fifth Tests”, see table 2 hereinafter), the laser marks 57a, 57b, 57c, 57d, 57e, 57f, 57g, 57h, 57i were produced with a neodymium YV04 laser operable at 1064nm. Each laser mark was about 2cm in length and had a line width of about 90pm, essentially determined by the laser beam diameter. Each laser mark was produced by moving the laser beam relative to the laminated glazing and each laser mark had a depth between 8-10 pm.

Figure 8 shows a schematic cross-sectional representation of another laminated glazing 71 in accordance with the present invention.

The laminated glazing 71 comprises a first sheet of glass 73 joined to a second sheet of glass 77 by a sheet of adhesive interlayer material 75 i.e. PVB. The second sheet of glass 77 is thinner than the first sheet of glass 73. The second sheet of glass 77 has a first major surface 76 in contact with the sheet of adhesive interlayer material 75 and a second exposed major surface 78. The first major surface 76 is opposite the second major surface 78. Both sheets of glass 73, 77 have a soda-lime-silicate glass composition and both sheets of glass have not been chemically strengthened.

The second sheet of glass 77 has a thickness 77’. The laminated glazing 71 has an exposed major surface 78 and on the second sheet of glass 77 is a first laser mark 79. The first laser mark 79 has an outline in the exposed surface 78 and a depth 79a in a thickness direction of the second sheet of glass 77. In this example the depth of the laser mark is defined by a depth of a cavity having an opening in the second exposed , maj .or surf >ace - 7,o8. - Tnhe d Jept1h - 7TO9a i •n mi •crons i -s at 1 least - ^D * thickness — 77' - (in microns) , w .here D i .s between 0.1 and 0.3.

For example, if the second sheet of glass 77 has a thickness 77’ of 2100pm (=2.1mm), then the depth 79a is at least 2.1 pm - 6.3 pm. It is preferred that D is 0.2, such that the depth 79a is at least 4.2 pm.

_T . . . .. . .. 1 w xthickness 77' (in microns) . ft is preferred that the depth 79a is less than - — - , where w is 25. Hence, in preferred embodiments the depth 79a is between 4.2 pm and 525 pm, although it is preferred that the depth 79a is less than 50 pm.

Figure 9 shows another laminated glazing 71 ’ that has essentially the same configuration as the laminated glazing 71 except in this example the second sheet of glass 77 has a laser mark 79’ on the first major surface 76. The first sheet of glass 73 is joined to the second sheet of glass 77 by the sheet of adhesive interlayer material 75. The laser mark 79’ was formed on the first major surface of the second sheet of glass 77 before lamination. The laser mark 79’ has an outline in the first major surface 76 and a depth 79a’ in the thickness direction of the second sheet of glass 77. In this example the depth of the laser mark is defined by a depth of a cavity having an opening in the first major surface 76. During lamination, some of the adhesive interlayer material 75 flows into the cavity formed by the laser mark 79’ and at least partially fills the cavity.

In figures 8 and 9, the laser marks are shown having an essentially flat base portion such that the depth of the laser mark is essentially constant over the laser mark. However, the laser mark may have variable depth over the laser mark, and in such embodiments the depth may be the maximum depth of the laser mark or the average depth of the laser marked region.

In an alternative to the embodiment shown in figure 9, there is also a laser mark 79 as shown in figure 8 in the major surface 78.

In another alternative embodiment to that shown in figure 9, the laser mark 79 does not comprise a cavity such that there is no opening in the first major surface 76. In such an example, the laser mark 79 still marks the first major surface 76 such that the laser mark has an outline in the first major surface 76, but the depth of the laser mark is due to a region of micro-cracked glass extending from the first major surface 76 towards the exposed major surface 78. A similar laser mark may be on at least one of the exposed major surface 78 and either major surface of the sheet of glass 73.

Figure 10 shows another laminated glazing 81 in accordance with the present invention.

The laminated glazing 81 comprises a first sheet of glass 83 joined to a second sheet of glass 87 by a sheet of PVB 85. The second sheet of glass 87 is thinner than the first sheet of glass 83. Both sheets of glass 83, 87 have a soda-lime-silicate glass composition.

The second sheet of glass 87 has a thickness 87’, which in this example is 2.1mm. The first sheet of glass has a thickness of 2.3mm, but the first sheet of glass may have the same thickness as the second sheet of glass.

The second sheet of glass 87 has a major surface 88 and on a portion thereof is a coating 90. The coating 90 is optically opaque and is an obscuration band. The coating 90 has a thickness 90’, which in this example is 50pm but may be in the range 10-30 pm. The coating 90 has a major surface 92. The combined thickness of the obscuration band and the second sheet of glass 87 is shown as thickness 94, measured relative to the major surface 92 of the coating 90.

The laminated glazing 81 has two laser marks 96 and 98. The laser mark 96 is a line having a width of about 90 gm and a depth 96’ of about 15 pm. The line has a substantially rectangular outline on the major surface 92 such that there is a substantially rectangular opening in the major surface 92. The laser mark 96 was made using a neodymium YVO4 laser operable at about 1064nm. As can be seen, the laser mark 96 has a cavity that extends into the coating 90 but is not deep enough to reach the underlying second sheet of glass 87.

The laser mark 98 is another line having a width of about 250 pm and a depth 98’ of about 60 pm. The line has a substantially rectangular outline on the major surface 92 such that there is another substantially rectangular opening in the major surface 92 associated with the laser mark 98.

The laser mark 98 was made using a CO2 laser operable at about 10.6 pm. As can be seen, the laser mark 98 has a cavity that extends through the entire thickness 90’ of the coating 90 and into the underlying second sheet of glass 87.

The depths 96’ and 98’ of the respective laser marks (in microns) are at least 0. 1 and 0.3. In this example the thickness 90’ of the coating 90 is only about 2.3% of the thickness 94, so the depths 96’ and 98’ of the respective laser marks (in microns) are also at least ^D _w | _lcrc D is between 0.1 and 0.3. Although the thickness of the coating contributes to the thickness 94, it is only a small contribution i.e. preferably less than 20% or preferably less than 15% or preferably less than 10%, such that the minimum depth of the required laser mark is still essentially determined based solely by the thickness 87’ of the second sheet of glass 87. If the thickness of the coating becomes more than 20% of the thickness of the underlying glass sheet, the combined thickness of the obscuration band and the second sheet of glass 87 (shown as thickness 94) may be used instead of the thickness 87’ of the second sheet of glass 87 in the calculation of the minimum depth of the laser mark.

In an alternative embodiment to that shown in figure 10, there is only laser mark 96.

In another alternative embodiment to that shown in figure 10, there is only laser mark 98.

In another alternative embodiment to that shown in figure 10, there is a laser mark in or on the major surface of the second sheet of glass 87 that is opposite the major surface 88, for example as shown in figure 9.

Note that although the laminated glazings shown in figures 8, 9 and 10 are depicted as flat, they may be curved, for example as shown in figure 1.

Figure 11 shows a schematic isometric representation of a portion of a sheet of glass 61 having a first major surface 62 and an opposing second major surface 63. There is a laser mark 64 on a portion of the second major surface 63. The laser mark 64 has been formed on a portion of the second major surface 63 that has does not have a coating or an obscuration band thereon. There may be an obscuration band and/or coating on other portions of the first and/or second major surfaces 62, 63 of the sheet of glass 61.

Either side of the laser mark 64 portions 63’ and 63” of the second major surface 63 are essentially unaltered by the laser that was used to produce the laser mark 64.

The laser mark 64 has an outline on the second major surface 63 comprising edge portions 65’ and 65 ” . In plan elevation, the outline is substantially rectangular and extends between opposing lateral edges of the glass sheet 61. The laser mark 64 may extend to one or both opposing lateral edges.

The portion 63’” of the second major surface having the laser mark thereon may have a different surface roughness than the surface roughness of the portions 63’, 63”.

The laser mark 64 has a width 66 being the spacing of the edge portion 65 ’, 65 ” . In between the first and second major surfaces 62, 63 the laser mark has caused a region of damage that is indicative of the depth of the laser mark 68.

The laser mark 64 may include an opening in at least a part of the surface portion 63 ’ ” but depth of such an opening is small compared to the depth of the laser mark 68, preferably being less than 20% or 10% or 5% of the depth of the laser mark 68.

With reference to figure 12, which is a cross-section through the plane X-X of figure 11, for a glass sheet 61 having flat, parallel major surfaces 62, 63, the depth of the laser mark 68 is the maximum distance of a normal from the untreated major surface (the surface before being provided with the laser mark 64) to a boundary where damage is no longer observable. In the event the portion 63’” becomes altered after having the laser mark provided, the distance 68 may be found by connecting tangents to the surface portions 63’ and 63” to determine the reference baseline from which the depth 68 may be calculated therefrom. Alternatively, if the major surface 62 aligned with the laser mark 64 is substantially unaltered after the laser mark has been provided on the major surface 63, the distance 68’ may be determined by drawing a normal from the first major surface 62 to a boundary 64’ defining the region of damage caused by the provision of the laser mark 64. Beyond the boundary 64’ (going from the first major surface 62 towards the second major surface 63) the glass is essentially crack free and undamaged due to the laser mark being provided on the major surface 63. The distance 68’ is the shortest length of a normal from the first major surface 62 to the boundary 64’. Once the distance 68’ has been found, the depth of the laser mark 68 may be calculated by subtracting the distance 68’ from the glass thickness 69. A scanning electron microscope may be used to identify the position of the boundary 64’.

A similar method may be used to determine the depth of a laser mark when the glass sheet is curved. This is illustrated in figure 13. Figure 13 shows a cross-section of a curved glass sheet 261. The curved glass sheet 261 has a first major surface 262 and an opposing second major surface 263. The first major surface 262 is a convex surface and the second major surface 263 is a concave surface.

Prior to providing a laser mark on the glass sheet 261, neither of the first and second major surfaces 262, 263 has a coating thereon i.e. there is no obscuration band on either of the major surfaces 262, 263.

Figure 13 also shows a laser mark 264 on the second major surface 263. In cross-section, the laser mark 264 has created a region of damage beneath the second major surface 263 defined by a boundary 264’. The depth of the laser mark may be calculated by finding the shortest length of a normal 268’ from a tangent F-F’ on the first major surface beneath the laser mark 264 to the boundary 264’. The depth of the laser mark can be found by subtracting the length of the normal 268’ from the glass thickness 269.

In an alternative to that shown in figure 13, there may be a laser mark the first major surface 262, either instead of the laser mark 264 on the second major surface 263, or as well as the laser mark 264 on the second major surface 263. When both major surfaces 262, 263 have a laser mark thereon, the laser marks may be aligned in a thickness direction of the glass sheet 261.

The glass sheets 61, 261 shown in figures 11-13 may be used as a sheet in a laminated glazing wherein the glass sheet 61, 261 is laminated to a second glass sheet via an interlayer structure comprising at least one sheet of adhesive interlayer material. Such a laminated glazing may have a laser mark on at least one of surface one, surface two, surface three or surface four.

Figure 14 shows the view from inside a vehicle that has a windscreen 100 in accordance with the present invention.

The windscreen 100 is essentially the same as the laminated glazing 1 previously described. The vehicle windscreen has a lower peripheral edge extending between the points E and F. The vehicle windscreen has an upper peripheral edge extending between the points D and G.

On the surface four (the inner facing surface) of the windscreen 100 are a plurality of laser marks. There is a first array of laser marks 174 that has twenty square laser marks (only one of which is labelled 175). Each square laser mark 175 has dimensions of between Ixlcm and 3x3cm. It is preferred all the squares 175 have the same size and/or area. The squares 175 are arranged in a line running parallel to the lower peripheral edge E-F i.e. the lower sides of the squares 175 are parallel to the lower peripheral edge E-F. The squares 175 may be orientated differently.

Each square 175 is laser ablated over the entire area thereof, although only selected regions may be laser ablated. For example, any or each square 175 may be in outline only, and the outline may be in the form of a continuous laser ablated line, or may comprise multiple disconnected laser ablated portions, alternatively, any or each square 175 may be comprise a pattern formed in the ablated surface. Such a pattern may arise when the laser ablated regions are sufficiently spaced apart. For example, when laser marking a square, the laser beam may cover the square region to be marked in a grid like manner. If between successive passes of the laser beam there is no overlap between the laser ablated regions, the laser marked region may appear to comprise a series of spaced apart parallel lines. However, if between successive passes of the laser beam there is an overlap between the laser ablated regions, the laser marked region may appear relatively flat in comparison.

In this embodiment also on surface four of the windscreen 100 is a second array of laser marks 172 running along the left hand peripheral edge D-E of the windscreen 100 and a third array of laser marks 176 running along the right hand peripheral edge. The second array of laser marks 172 has seven square regions (only one of which is labelled 173) with a lower side thereof being parallel to the left hand peripheral edge D-E. The third array of laser marks 176 also has seven square regions (only one of which is labelled 177) with a lower side thereof being parallel to the right-hand peripheral edge F-G.

Each of the laser marks in the second and third arrays are the same size and/or have the same area.

Prior to forming the laser marks, the glass sheet is smooth. Following laser marking the laser marks may be rougher. According to “Glass Processing Days, 13-15 Sept 1997, pages 40-44, the surface roughness of float glass has Rz < 0.1 pm. It is preferred that the laser marks be translucent following laser marking.

In order to test the effect of having portions of surface four of the laminated glazing laser marked, the ease with which a laminated glazing broke following an impact on surface one was determined. The same test may be used when the laminated glazing has laser marks on any of any combination of the other surfaces one, two or three of the laminated glazing.

With reference to figure 15, a laminated glazing to be tested was constructed using conventional lamination conditions and comprises a first sheet 153 of soda-lime-silicate glass joined to a second sheet 157 of soda-lime-silicate glass by means of a sheet of PVB 155. The laminated glazing 151 was in the form of a vehicle windscreen and may have obscuration bands thereon, as is conventional in the art. Neither of the first or second sheets 153, 155 was chemically strengthened.

The first sheet 153 has an exposed major surface 159, and this is “surface one” (or SI) of the laminated glazing 151. The major surface 159 is convex.

The second sheet 157 has an exposed major surface 161, and this is “surface four” (or S4) of the laminated glazing 51. The major surface 161 is concave.

Portions of the major surface 161 were laser marked as described with reference to figures 2, 3 and 6.

Whatever the arrangement of laser marks, the laminated glazing was tested as follows, and with reference to figure 15. The laminated glazing 151 was first positioned in a horizontally arranged frame (not shown) and clamped therein about the periphery. The major surface 159 (“surface one”) was facing upwards and able to be freely contacted i.e. the frame does not impede contact with the major surface 159.

An impactor 167 is then dropped onto surface 159 at an impact location being a central position lying substantially on the centreline of the laminated 151 glazing, about 15cm - 30cm away from the lower peripheral edge of the laminated glazing, the actual distance away from the lower edge peripheral edge of the laminated glazing being kept the same in the tests.

The impactor 167 used in the tests is a plastic hollow spheroid filled with steel shot and covered with felt. The overall weight of the impactor 167 is 4.5kg and the overall diameter is 165mm.

The impactor used in the tests is similar to that specified in UN Regulation No. 127 (E/ECE/324/Rev.2/Add. 126/Rev.2).

The impactor 167 was positioned directly above the impact location at a height sufficient for the impactor to reach a speed of 40km/h at the impact location (by equating the potential energy to the acquired kinetic energy). The impactor 167 is directly above the impact location and will be released to fall under gravity in the direction of arrow 168 to strike the major surface 159 at the impact location.

To ensure the same impact position on each sample, a plumb line may be used to position the impactor 167 at the desired position for contact with the glass surface when dropped.

To assess the way the laminated glazing breaks when the impactor 167 is dropped onto the laminated glazing 151 as described above, the test is recorded using a video camera 170 positioned above the laminated glazing 151. The video camera 170 operates at a high frame rate, for example a thousand frames per second (lOOOfps).

To classify the ease with which the laminated glazing 151 breaks, two breakage criteria were identified by examining the video recording made during the test.

The first breakage criteria is referred to as the “Initial Breakage Time” and is the time taken for the first cracking to be seen in the laminated glazing following the impactor 167 making contact with the major surface 159 at the impact location.

The second breakage criteria is referred to as the “Full Breakage Time” and is the time taken for the laminated glazing 151 to undergo catastrophic breakage following the impactor 167 making contact with the major surface 159 at the impact location.

To help identify the Initial Breakage Time and/or the Full Breakage Time, one or more reference marks may be provided on major surface 159, especially in the region of the chosen impact location. The reference marks may be in the form of a grid and may be applied to the major surface 159 using a suitable pen or the like. A number of laminated glazing samples were evaluated as described above. Each laminated glazing had essentially the same degree of curvature. The results are provided in tables 1 and 2.

The results in table 1 are for laminated glazings without any laser marks.

The samples in table 1 and table 2 are defined in terms of an outer pane and an inner pane. With reference to figure 15, the first sheet 153 is referred to as an “outer pane”, because when the laminated glazing 151 is installed in a vehicle, the first sheet 153 faces the exterior of the vehicle. Accordingly, the second sheet 157 is referred to as an “inner pane”, because when the laminated glazing 151 is installed in a vehicle, the second sheet 157 faces the interior of the vehicle. The impactor 167 therefore strikes the outer pane to simulate the impact with a pedestrian who may be involved in a forward collision with a vehicle in which the laminated glazing 151 is installed i.e. as shown in figure 14.

The sample details and results are provided in each table. Each of the inner and outer panes is a sheet of soda-lime-silicate glass (made using a conventional float process i.e. “float glass”) at the quoted thickness. The inner and outer panes are joined by a sheet of PVB 0.76mm thick. Neither of the inner and outer panes was chemically strengthened in these samples.

In the table 2 below, the three different types of laser marks were tested. The first type of laser marks were “Full Squares”, see for example figure 2 and the related description thereof. The second type of laser marks were straight lines parallel to the lower peripheral edge of the laminated glazing and spaced about 5cm therefrom, see for example figures 3-5 and the related description thereof. The third type of laser marks were outline squares, see for example figures 6 and 7 and the related description thereof.

Where provided in the table, the average depth of the laser marks were measured using a Hommel Tester T500 Profilometer.

In order to illustrate the effect of the laser marks, information the Initial Breakage Time and the Full Breakage Time are each provided in milliseconds (ms). For the particular set of tests, the results are provided in the format of a minimum Initial Breakage Time for the set of glazings being tested, a maximum Initial Breakage Time for the set of glazings being tested and the average Initial Breakage Time for the set of glazings being tested. For example, for the “First Tests”, the minimum Initial Breakage Time for the nine samples tested was 2.00ms; the maximum Initial Breakage Time for the nine samples tested was 3.00ms and the average Initial Breakage Time for the nine samples tested was 2.60ms. The results for the Final Breakage Time are presented in the same way.

In table 1, samples Comparative 1 - 4 have inner and outer panes of soda-lime-silicate glass of thickness 1.8mm joined by a 0.76mm sheet of PVB. Samples Comparative 5 - 8 have inner and outer panes of soda-lime-silicate glass of thickness 1.4mm and 1.8mm respectively joined by a 0.76mm sheet of PVB. There are no laser marks on the Comparative samples 1 - 8. The results in table 1 show that without any laser marks (Comparative 1-8), the laminated glazing has an Initial Breakage Time between 4-6ms after surface 159 is struck by the impactor 167 at the impact region. The majority of the Comparative samples have an Initial Breakage Time of 5ms.

As can be seen from table 1, the Final Breakage Time occurs shortly after the Initial Breakage Time, typically within a millisecond thereof.

The results in table 2 illustrate that providing surface four of the laminated glazing with different types of laser marks (of the type previously described), the Initial Breakage Time is reduced. The Final Breakage Time is also reduced.

This indicates that upon an impact with surface one of the windscreen, for example by a forward collision with a pedestrian, the windscreen having the laser marked regions is easier to break. The reduction in the rigidity of the windscreen upon breakage may result in less serious injury to the pedestrian.

It is to be expected that instead of an array of full squares or outline squares, other shape laser marks would behave in a similar manner, for example diamonds, circles, trapeziums, or other irregular shapes. Symmetrical laser marks and/or same shaped laser marks may provide the laminated glazing with the benefits detailed in table 2 at more than one impact location on surface one of the windscreen.

It is also expected that similar improvements would be obtained having laser marks as herein described in or on surface three of the laminated glazing, that is, in the surface of the second sheet 157 opposite the major surface 161.

It also may be expected that similar benefits are observed when using other similar tests to determine the breakage properties of the laminated glazing, for example as described in UN Regulation No. 127 (E/ECE/324/Rev.2/Add. 126/Rev.2).

Accordingly, a laminated glazing for a vehicle windscreen is described comprising first and second glass sheets joined by a sheet of adhesive interlayer material. A first region of a first major surface of the second glass sheet is spaced apart from a first region of a second opposing major surface of the second glass sheet in a thickness direction of the second glass sheet by a distance t in microns. On the first region of the second major surface of the second glass sheet is a first laser mark having a depth d in the thickness direction of the second glass sheet, wherein d in microns is at least (D x /)/ 100 and D is between 0.1 and 0.3. A method of making such a laminated glazing is described. Such a laminated glazing may be used to reduce the time taken to break upon being impacted on an exposed major surface thereof.

It has been found that by having laser marks on a major surface of the laminated windscreen, the laminated glazing is easier to break in the event of a pedestrian colliding with the outer facing surface of the laminated windscreen.

Table 1

Table 2