Sheet-like, water-repellent sealing material for roofs and outside walls

The invention relates to a sheet-like, water-repellent sealing material for roofs, outside walls and the like. The invention further comprises a method for manufacturing such a water-repellent sealing material.

Sheet-like materials such as for instance lead flashing are frequently applied for water- repellent sealing of parts of roofs and outside walls. Such materials are generally arranged in the form of strips on parts of roofs and outside walls where the roof or outside wall structure is interrupted, such as for instance in the case of chimneys, dormer windows, skylights, lead coping, roof ducts, roof gutters and doors, windows, sliding doors and other connections to parts of a building. Joins into which water can readily seep are created at locations where the roof or outer wall construction is interrupted, and this is of course undesirable. In order to ensure that water-repelling can take place properly, the sheet-like material must be readily deformable at ambient temperature without the material beginning to break or crack easily when it is arranged. Lead flashing has this property and can be deformed plastically (and therefore practically permanently) reasonably easily by means of processing with a hammering tool, generally referred to by the skilled person as "hammering out". The contours of the roof and outside wall structure can hereby be followed accurately.

Although lead flashing can be deformed well when cold, this material does contain lead. Lead is a toxic heavy metal which accumulates in living organisms and is thus harmful to the environment. Lead is therefore increasingly being banned as a building material. Lead flashing is moreover responsible for a considerable percentage of the total lead emission to surface water.

Known from DE 42 28 444 Al is a roofing material which comprises a perforated metal sheet provided on both sides with a plastic film. In order to improve the adhesion between metal sheet and plastic film, a glass fibre can be arranged therebetween.

GB 2 099 474 A describes a sealing material which comprises a bituminous layer provided with a protective film. The other side of the sealing material is provided with a non-adhesive film.

Further known from NL 1 009 983 C2 and EP 1 426 519 Al are water-repellent sealing materials of a laminate of two metal layers and a plastic layer therebetween.

The sealing materials known from the prior art require improvement for several reasons. They do not for instance display the desired deforming behaviour, or do so to a lesser extent, as will be further discussed hereinbelow.

The invention has for its object to provide a sheet-like, water-repellent sealing material of the type stated in the preamble which is readily deformable, has a good water- repellent action and which does not have the above stated drawbacks of lead flashing, or does so to lesser extent.

According to the invention a sheet-like, water-repellent sealing material is provided which comprises a laminate of two metal layers and at least one fibre-reinforced plastic layer therebetween and connected thereto, wherein at least the outer layers of the laminate are metal layers. Through the measures as stated in claim 1 a material is obtained which can be readily arranged on substrates for sealing. Within the scope of this application sheet-like is understood to mean that the material is sufficiently flexible to allow relatively simple deformation at ambient temperature. Because the fibre- reinforced plastic layers in the sheet-like material according to the invention are connected to the metal layers, the deformability is achieved by limiting the overall thickness of the material - and therefore also the thickness of the layers from which the material is built up. It has been found that the material according to the invention can be readily formed into the required shapes at ambient temperature without this resulting in substantial cracking in the material or in any of the layers, even after repeated deformation. An additional advantage of the material according to the invention is that it is no longer necessary to hammer out the material for a good sealing. The material can also be arranged easily round shapes with a relatively small radius of curvature.

Laminates of at least a metal layer and a fibre-reinforced plastic layer (also referred to as fibre laminate) connected thereto are known per se for application in, among others, the transport industry, such as for instance in cars, trains, aircraft and spacecraft. The known fibre metal laminate is however constructed from a large number of aluminium

sheets with fibre-reinforced plastics arranged therebetween, and is much thicker, whereby it is not sheet-like but, on the contrary, has a high rigidity.

It is noted that a laminate of metal layers and fibre-reinforced plastic layers is described in EP-A-I 312 468. The fibre-reinforced plastic layers comprise metal cords. The laminate can be applied as construction panel. Paragraph [0041] of EP-A-I 312 468 states that the laminate has a high bending stiffness. The use of the laminate as foldable, water-repellent sealing material is not described.

According to the invention the thickness of the sheet-like material and of the layers from which the material is constructed is small, but can be varied within the requirements set for the deformability of the material. Factors which can affect the deformability are, among others, the properties of the metal from which the metal layers are built up, the properties of the fibre-reinforced plastic layers, the number of layers from which the material is constructed and the level of adhesion between the different layers. A preferred embodiment of the sheet-like material according to the invention is characterized in that the metal layers have a thickness ranging between 0.01 and 0.5 mm, more preferably between 0.05 and 0.3 mm, and most preferably between 0.08 and 0.19 mm. It has been found that a material according to this preferred variant has an increased resistance to cracking. It has been found particularly that such a material can be bent around a relatively small radius of curvature several times and folded back again without substantial cracking occurring. The material displays hardly any fatigue under the influence of dynamic load. In other words, the material hardly stiffens under cyclic load, whereby a brittle fracture is less likely to occur. Although the mechanism is not understood by the inventors, it has been found that the reinforcing fibres are an essential factor in the fibre-reinforced plastic layer.

If the fibre-reinforcement is omitted from the plastic layer, it is then found that such a material can hardly be bent around a relatively small radius of curvature and folded back again without cracking occurring in at least one of the metal layers, or without folding seams remaining visible.

A further preferred embodiment has the feature that the metal of the metal layers is chosen from the group of aluminium, aluminium alloys, steel, steel alloys, stainless steel, metal-coated steel, magnesium and copper. Such metals have the advantage that they have considerably less of an environmental impact than heavy metals such as lead. The deformation behaviour desired for the present application is obtained by combining these metals according to the invention with fibre-reinforced plastic layers. A single metal layer does not have this deformation behaviour. It is not however precluded according to the invention that at least a part of the sheet-like material comprises lead. A material according to the invention partially comprising lead has the advantage that the favourable properties of lead can be utilized. Such a material will thus have an increased specific weight, whereby less wind lift will occur. Wind lift is understood to mean that the material is lifted upward under the influence of the wind. There is however less of an environmental impact because the material contains less lead than lead flashing.

A particularly advantageous embodiment of the sheet-like material according to the invention has the feature that the metal of at least a part of the metal layers comprises aluminium or an aluminium alloy. Aluminium alloys particularly suitable for application are non-alloy or low-alloy aluminium in soft state. Aluminium alloys are light, whereby a material according to this preferred variant is easy to handle and can be supplied in large quantities. A further advantage is that the sheet-like material displays hardly any creep under prolonged load. Creep is often a problem in the use of lead flashing, wherein arranged lead flashing sags over time and thereby no longer seals properly.

A preferred variant relates to a sheet-like material, the metal of at least a part of the metal layers of which has an elongation at break of at least 5%. Soft metals with an elongation at break of at least 5% preferably also have a low limit of stretch. Although a material of such a metal can be readily deformed plastically, such a material is per se unusable as a water-repellent, sheet-like material, among other reasons because the desired dynamic deformation behaviour is not obtained. Cracking thus occurs after repeated deformation and/or a folding seam is for instance formed which remains visible and cannot be removed. Surprisingly, the desired dynamic deformation

behaviour is however obtained by combining the metal layers with fibre-reinforced plastic layers as according to the invention.

A further preferred embodiment of the sheet-like material according to the invention comprises metal layers and/or fibre-reinforced plastic layers, at least a part of which, and preferably at least the outer layers, is provided with an organic coating. Such a coating can for instance comprise a coloured coating. This has the advantage that, if desired, the sheet-like covering material can take on the same colour as for instance the roof tiles of a roof, which results in an aesthetic advantage. Another possibility is a coating with anti-reflective properties. It is also possible for the coating to form an anti- corrosive coating or to form an adhesive layer for adhering the sheet-like material to a substrate and/or for adhering other materials to the sheet-like material. For this latter functional property even a thermosetting or thermoplastic adhesive layer can be applied, which remains tacky or which is pressure-sensitive. This results in a kind of tape which, by being pressed, remains directly adhered to the substrate. In a particular embodiment variant this tacky side can be covered with an easily removable film (for instance of polyethylene).

When metal layers and/or fibre-reinforced plastic layers are referred to in this application, they can also be understood to mean a single metal layer and/or fibre- reinforced plastic layer.

The fibre-reinforced plastics applied in the sheet-like material are light and strong and comprise reinforcing fibres embedded in a plastic. The plastic also serves as adhesive between the different layers. Reinforcing fibres which can be suitably applied in the fibre-reinforced plastic comprise for instance glass fibres, carbon fibres, metal fibres, although if desired can also be reinforced thermoplastic synthetic fibres such as for instance aramid fibres, PBO fibres (Zylon®), M5® fibres and ultra-high molecular weight polyethylene or polypropylene fibres, as well as natural fibres such as for instance flax, wood and hemp fibres, and/or combinations of the above stated fibres.

Particularly suitable reinforcing fibres are glass fibres, in particular E-glass fibres, since these enhance the desired deformation behaviour of the water-repellent sealing material. Examples of suitable matrix materials for the reinforcing fibres are thermoplastic plastics such as polyamides, polyurethanes, polyethylene, polypropylene, acrylonitrile

butadiene-styrene (ABS), styrene maleic anhydride (SMA), polycarbonate, polyphenylene oxide (PPO), thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, and mixtures and copolymers of one or more of the above stated polymers. Suitable matrix materials likewise comprise thermosetting plastics such as epoxies, unsaturated polyester resins, melamine-formaldehyde resins, phenol formaldehyde resins, polyurethanes and the like.

In a preferred embodiment of the sheet-like material according to the invention an adhesive layer is present between one metal layer and one fibre-reinforced plastic layer. Such an adhesive layer can be applied separately between the relevant layers, for instance by means of a suitable applicator device. Both adhesion on the basis of thermosetting resins and adhesion on the basis of thermoplastic plastics are in principle suitable. It is also possible for the adhesive layer to be formed by the matrix material of the fibre-reinforced plastic.

A particularly suitable sheet-like material has the feature that the adhesive layer is a thermoreversible adhesive layer which is preferably applied to the metal layer. Thermoreversible adhesives are per se known to the skilled person and have the property that, after being brought to temperature, they can be melted at least once more, this in contrast to a thermosetting adhesive, which can no longer be melted after setting thereof. Highly suitable thermoreversible adhesives are commercially available, for instance from CCT B.V., under the brand names AD Adhesive Rl 2 and AD Adhesive R23. Suitable techniques for applying the thermoreversible adhesive to the metal layer include laminating, spraying, dipping, coating with a roller, coil-coating and immersion. Suitable thermoreversible adhesives can be combined with the metal and/or the plastic, and can further be melted again at least once more. The adhesive is preferably chosen such that the adhesive layer applied as a result of the coating process is substantially dry (does not display any tackiness), so that the pre-coated layers can be stacked and/or rolled up in simple manner. If the thermoreversible adhesive is provided beforehand on the metal layer or layers and/or on the fibre-reinforced plastic layer or layers, the thickness is preferably between 1 and 100 micrometres, more preferably between 5 and 30 micrometres. If desired, the thermoreversible adhesive layer can be an adhesive film. If the thermoreversible adhesive layer is applied as a separate film, the thickness of this

film preferably lies between 1-100 micrometres, and more preferably between 20 and 80 micrometres.

A further preferred embodiment of the sheet-like material is assembled by combining adhesive layers with a 'dry' fibre reinforcement (i.e. without matrix). According to this method the total adhesive layer is preferably applied thickly (20-400 microns) because the adhesive must almost fully impregnate the fibre-reinforcing material, after which the adhesive has in fact become the matrix material of the fibre-reinforced plastic.

In the laminate according to the invention the fibre-reinforced plastic of one or more layers preferably comprises substantially continuous fibres which extend substantially in one direction (so-called UD material). It is however also possible for the fibre- reinforced plastic layers to comprise discontinuous fibres which, if desired, run in random directions through the layers. It is also possible for the fibre-reinforced plastic layers to be built up at least partly of so-called random mats. There are further advantages in applying the fibre-reinforced plastic in the form of a pre-impregnated semi-manufacture. After setting thereof, such a "prepreg" generally has good mechanical properties, among other reasons because the wetting of the fibres by the plastic matrix has already taken place beforehand.

A particularly suitable embodiment of the sheet-like material according to the invention comprises fibre-reinforced plastic layers which comprise substantially continuous fibres extending in two almost orthogonal directions. Fibre-reinforced plastic layers which comprise substantially continuous fibres extending in two almost orthogonal directions can for instance be built up of a fabric or knit of a reinforcing fibre and a plastic matrix. It has been found that a sheet-like material according to the present preferred variant displays a particularly favourable deformation behaviour, wherein the material can on the one hand be easily folded into many forms, but can on the other hand be folded back many times into the original form or, if desired, into another form, and wherein the folds made are also scarcely visible after they have been folded back. A further improved deformation behaviour is obtained when the fibre-reinforced plastic layers in the material have a thickness ranging between 0.01 and 1 mm, and more preferably between 0.05 and 0.3 mm. The inventors attribute the above stated exceptional deformation behaviour of the material according to the invention to the specific

combination of metal layers and fibre-reinforced plastic layers applied therein. The described deformation behaviour is highly suitable in the application as water-repellent material.

The sheet-like, water-repellent material according to the invention can be obtained by mutually connecting a number of metal layers and intermediate fibre-reinforced plastic layers, for instance by means of heating under pressure, and subsequently cooling them. Depending on the intended application and the set requirements, particularly in respect of the desired deformability, the optimum number of metal layers can be easily determined by the skilled person. Because the material must be sheet-like and therefore relatively flexible, the total number of metal layers in the material will preferably amount to no more than 5, more preferably no more than 3, and most preferably no more than 2, although the invention is not limited to laminates with such a maximum number of metal layers.

A particularly suitable preferred variant provides a sheet-like material which is built up of at least two metal layers with a thickness ranging between 0.05 and 1 mm, and a fibre-reinforced plastic layer therebetween with a thickness ranging between 0.05 and 1 mm.

Another preferred variant of the sheet-like material according to the invention has the feature that the material is obtained by continuously supplying and stacking at a first temperature the at least one metal layer in the form of a continuous metal sheet and the at least one fibre-reinforced plastic layer, and subsequently consolidating them into the sheet-like material using at least one forming roller brought to the second temperature.

The invention will now be further elucidated with reference to the following schematic figures, without however being limited hereto.

Figure 1 shows a schematic section of a preferred variant of the sheet-like material according to the invention,

Figure 2 shows schematically a material according to the invention in deformed state; and

Figure 3 shows schematically the material according to the invention after it has been returned to the non-deformed state from the deformed state shown in figure 2.

Figure 1 shows a flexible, sheet-like material 1 according to the invention with a total of three layers. It is noted that the layer thicknesses indicated in the figures do not necessarily correspond with the actual thickness ratios. Laminate 1 comprises two metal layers 2 and 3 with a thickness of about 0.1 mm of a suitable aluminium alloy on both outer sides. The core of laminate 1 is formed by a fibre-reinforced plastic layer 10 with a thickness of about 0.2 mm, which is connected on either side to metal layers 2 and 3. Layers 2 and 3 can be constructed from a different metal. In the shown preferred variant metal layers 2 and 3 are provided on the sides facing each other with a thermoreversible adhesive layer 4. Metal layers 2 and 3 can further be provided with a pretreatment layer 5, which can comprise a conversion layer or primer, and with a decorative and/or functional cover layer 6.

A preferred variant of sheet-like material 1 according to the invention was obtained by stacking an aluminium sheet, of about 0.1 mm thick and provided with a conversion layer on the inner side thereof, with adhesive film and a glass fabric in a 1:1 ratio, with an overall surface area weight per area of 700 g/m ² , and another aluminium sheet of about 0.1 mm thick and provided with a conversion layer on the inner side thereof, and subsequently consolidating by applying pressure and increased temperature. Consolidation took place in continuous manner by carrying the different component materials through a rolling train. It is however also possible to manufacture the sheet- like material in batches, for instance in a press.

Figure 2 shows the material shown in figure 1 after it was shaped along a fold line X-X. Figure 3 shows the same material after it was returned to the original, flat form from the deformed state shown in figure 2. As can be seen in Figure 2, the material can be readily deformed with a small radius of curvature without this resulting in cracking and/or a full break. As shown schematically in Figure 3, the folding seam created during the deformation is no longer visible, or hardly so, after repeated return of the material to the original, flat form. The material thus behaves as if no permanent deformation has occurred during the shaping thereof.

Different modifications can be made within the scope of the invention. Although in the first place metal layers of equal thickness are used in the laminates according to the invention, it is also possible in principle to apply metal layers of two or more differing thicknesses in an optionally symmetrical stack in one and the same laminate. If desired, the sheet-like material can further have a progressive thickness and/or a local progression in thickness, for instance in order to increase the deformability thereof.