METHOD FOR PROVIDING A PERFORATION LINE HAVING ENHANCED VISIBILITY ON A FIBROUS WEB MATERIAL, FIBROUS WEB MATERIAL OBTAINED BY THE METHOD AND FIBROUS WEB MATERIAL

TECHNICAL FIELD

The present invention relates to a method for providing a perforation line having enhanced visibility on a fibrous web material, which perforation line extends transversely across the fibrous web material and which perforation line comprises a plurality of perforation apertures. In addition, the present invention relates to a fibrous web material obtained by means of the method. Furthermore, the present invention relates to a fibrous web material comprising at least one perforation line, whereby each perforation line extends transversely across the fibrous web material and whereby each perforation line comprises a plurality of perforation apertures.

BACKGROUND OF THE INVENTION

A fibrous web material intended to be used for wiping or personal hygiene is commonly provided with tear perforation lines extending transversely across the fibrous web material at spaced apart locations thereof. The perforation lines divide the fibrous web material in the length direction into individual sheets of a specific size. Furthermore, each perforation line constitutes a line of reduced tensile strength, whereby easy separation of the individual sheets is promoted. Thus, the provision of perforation lines on a fibrous web material is intended to aid dispensing of the fibrous web material. A consumer may easily tear a fibrous web material being provided with perforation lines into individual sheets having a preset size due to the presence of the perforation lines. Examples of fibrous web materials intended to be used for wiping or personal hygiene are toilet paper, kitchen paper, napkins, serviettes, handkerchiefs, paper towels, towels, wipes, different types of cloths, make-up removal towels, facial tissue, cosmetic tissue, baby wipes, kitchen towels, kitchen wipes, cleaning wipes and industrial wiping material.

In order to promote usage of perforation lines provided on a fibrous web material it is important that the perforation lines are readily identifiable. In case the perforation lines are not easy to identify, there is a risk that a consumer does not utilize the perforation lines when a piece is to be torn off from the fibrous web material. Consequently, irregular edges

may result on both a piece torn off and on the remainder of the fibrous web material. Irregular edges may imply that the use of the piece torn off may be difficult or inconvenient. Furthermore, the inability to easy identify the perforation lines may often also result in unnecessary waste. In addition, in case the perforation lines are not readily identifiable and a consumer does not utilize the perforation lines when a piece is to be torn off from the fibrous web material, it might be necessary for the consumer to grip the piece to be torn off with one hand and the remainder of the fibrous web material with the other hand in order to enable separation. The grip of the remainder of the fibrous web material may be unhygienic.

Today many fibrous web materials intended to be used for wiping or personal hygiene comprise perforation lines that might be difficult to readily identify even for people having good eyesight. Under certain circumstances identification of the perforation lines on a fibrous web material may as well be further inhibited to a greater or less extent. One example of such a circumstance is a low light condition. Furthermore, since even people having good eyesight may have problems to identify the perforation lines, elderly people with limited vision and visually handicapped people may have particular problems to identify the perforation lines. However, on the market today there are fibrous web materials comprising perforations lines having enhanced visibility, i.e. there are fibrous web materials on which the identification of the perforation lines is promoted. For example, US 4,238,541 describes such a fibrous web material.

More specifically, US 4,238,541 describes a rolled web of paper, which has a plurality of tear perforation lines and which comprises an identifying marker at each tear perforation line in order to enhance the visibility of the perforation lines. The identifying marker may be a printed ink marker or an embossed marker. In one embodiment the rolled web of paper comprises a printed arrow at each end of each perforation line. In another embodiment the rolled web of paper comprises a printed marking strip superimposed onto each perforation line. In still another embodiment the rolled web of paper comprises impressions embossed in the web of paper adjacent each perforation line.

In production of a rolled web of paper according to US 4,238,541 (or any other fibrous web material having a plurality of perforation lines and comprising a printed or embossed identifying marker at each perforation line), the perforation lines and the identifying markers must be provided on the web in separate production steps. More specifically,

each perforation line must then be produced in a perforating production step and the identifying marker belonging to the respective perforation line must be produced in a subsequent printing or embossing production step. Thus, when the identifying markers are to be provided on the web, the respective perforation lines are already present on the web. However, it is difficult from a production aspect to correlate the printing or embossing production step with perforation lines already present on the web. Thereby, it is difficult to ensure that the printed or embossed markers are provided on the web at the exact desired positions, i.e. at positions in relation to the perforation lines such that they exactly mark the positions of the perforation lines. Thus, there is a risk that a product thus produced comprises identifying markers that do not exactly mark the perforation lines. In case an identifying marker does not exactly mark the position of a perforation line, a position on the web not comprising a perforation line is marked. Then the wrongly positioned identifying marker does not fulfil its aim and may instead influence a consumer to not use the perforation line.

Furthermore, in order to provide a rolled web of paper according to US 4,238,541 (or any other corresponding fibrous web material) additional printing or embossing equipment for the production of the identifying markers must be added to the usual perforating equipment for providing the perforation lines.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an improved method for providing a perforation line having enhanced visibility on a fibrous web material, which perforation line extends transversely across the fibrous web material and which perforation line comprises a plurality of perforation apertures, by which method one or more of the disadvantages of the previously known technology discussed above are eliminated or at least reduced.

This object is achieved through a method comprising the steps of:

- providing a perforation knife having a plurality of teeth, which perforation knife is to be utilized for producing the perforation line comprising a plurality of perforation apertures on the fibrous web material during a perforation operation and which perforation knife teeth each comprises a perforation portion arranged to produce one perforation aperture during the perforation operation;

applying a layer of an ink at least partly to the perforation portion of each of at least two teeth of the perforation knife before the perforation operation is performed, which ink has a colour contrasting with the fibrous material in the fibrous web material; positioning the fibrous web material and the perforation knife in relation to each other for enabling the perforation operation to be performed at an intended location on the fibrous web material, and performing the perforation operation by perforating the fibrous web material by means of the perforation knife, whereby the perforation line comprising a plurality of perforation apertures is produced and ink is transferred from those perforation portions provided with the ink to at least parts of the circumference of the corresponding perforation apertures thus produced.

In a further aspect of the present invention, there is provided a fibrous web material obtained by the above method.

Another object of the present invention is to provide an improved fibrous web material comprising at least one perforation line, whereby each perforation line extends transversely across the fibrous web material product and whereby each perforation line comprises a plurality of perforation apertures, in which fibrous web material one or more of the disadvantages of the previously known fibrous web material discussed above are eliminated or at least reduced.

This object is achieved in accordance with the characterizing portion of claim 14.

Still other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference characters denote similar elements throughout the several views:

Figure 1 a shows a schematic perspective view of one example of an apparatus for performing a first embodiment of the method according to the invention, Figure 1b shows a schematic perspective view of a variant of the example of an apparatus for performing a first embodiment of the method according to the invention shown in figure 1a, Figure 2 shows a schematic side view of one non-limiting example of a basic configuration of a perforation knife,

Figure 3 shows a schematic side view of one example of an apparatus for performing a second embodiment of the method according to the invention, Figure 4 shows a schematic side view of one example of an apparatus for performing a third embodiment of the method according to the invention,

Figure 5 illustrates a first embodiment of a fibrous web material according to the invention, Figure 6 illustrates a second embodiment of the fibrous web material according to the invention, and Figure 7 illustrates a third embodiment of the fibrous web material according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1a shows a schematic perspective view of one example of an apparatus 1 for performing a first embodiment of the method according to the invention. The apparatus 1 may be utilized for providing one or more perforation lines 18 having enhanced visibility on a fibrous web material 2, whereby each perforation line 18 extends transversely across the fibrous web material 2 and whereby each perforation line 18 comprises a plurality of perforation apertures 19. The fibrous web material 2 is arranged to run in the direction of the arrow in figure 1a. As utilized herein, the term "perforation line" is to be understood as a line comprising a plurality of perforation apertures 19 (at least two perforation apertures 19), whereby a bonded area 20 of fibrous material is located between each pair of consecutive perforation apertures 19. The term "aperture" is herein to be understood as an opening, a cut, a slit or the like and may have any suitable shape. The term "bonded

area" is herein to be understood as an area in a perforation line 18 between two consecutive perforation apertures 19.

The term "fibrous web material" is herein to be understood to include paper web materials and nonwoven web materials.

The term "paper web material" is herein to be understood to include tissue paper web materials.

The term "tissue paper" is herein to be understood as a soft absorbent paper having a basis weight below 65 g/m ² and typically between 10 and 50 g/m ² . Its density is typically below 0.60 g/cm ³ , preferably below 0.30 g/cm ³ and more preferably between 0.08 and 0.20 g/cm ³ . Moist tissue paper webs are usually dried against one or more heated rolls. A method which is commonly used for tissue paper is so called yankee drying. At yankee drying the moist paper web is pressed against a steam-heated yankee cylinder, which can have a very large diameter. The paper web is usually creped against the yankee cylinder. Another drying method is so called through-air-drying (TAD). In this method the paper is dried by means of hot air blown through the moist paper web, often without a preceding wet pressing. In connection with the TAD drying the patterned structure of the drying fabric is transferred to the paper web. This structure is essentially maintained also in wet condition of the paper, since it has been imparted to the wet paper web.

In the international patent application no. PCT/SE98/02461 there is disclosed a method for producing an impulse dried paper, especially tissue paper, having a three-dimensional pattern, said paper having high bulk and softness. Impulse drying shortly involves that the moist paper web is passed through the press nip between a press roll or press shoe and a heated roll, which is heated to such a high temperature that a quick and strong steam generation occurs in the interface between the moist paper web and the heated roll. The three-dimensional embossment pattern is accomplished by means of a pattern provided on the heated roll. The counter means, for example a press felt, against which the paper is pressed in connection with the simultaneous impulse drying and shaping, has a non- rigid surface.

The tissue paper in the present invention may be any type of tissue paper. The tissue paper may be creped or non-creped. The creping may take place in wet or dry condition.

It may further be foreshortened by any other methods, such as so called rush transfer between wires.

The fibres contained in the tissue paper are mainly pulp fibres from chemical pulp, mechanical pulp, thermo mechanical pulp, chemo mechanical pulp and/or chemo thermo mechanical pulp (CTMP). The fibres may also be recycled fibres. The tissue paper may also contain other types of fibres enhancing e.g. strength, absorption or softness of the paper. These fibres may be made from regenerated cellulose or synthetic material such as polyolefins, polyesters, polyamides etc.

The tissue paper coming out from the tissue machine as a single-ply paper sheet may be converted to the final tissue product in many ways, for example embossed, laminated to a multi-ply product, rolled or folded. A laminated multi-ply tissue product comprises at least two tissue plies, which are often joined by either adhesive or mechanically. The adhesive may be applied all over the paper or just in regions, for example dots or lines, or only along the edges of the product. The mechanical methods are mainly embossing either over the entire area of the plies or only along the edges, so called edge embossing.

The tissue paper coming out from the tissue paper machine may comprise one or more layers. In the case of more than one layer this is accomplished either in a multi-layered headbox, by forming a new layer on top of an already formed layer or by couching together already formed layers. These layers can not or only with considerable difficulty be separated from each other and are joined mainly by hydrogen bonds. The different layers may be identical or may have different properties regarding for example fibre composition and chemical composition.

The term "nonwoven" is applied to a wide range of products which in term of their properties are located between the groups of paper and cardboard on the one hand and textiles on the other hand. As regards nonwoven a large number of extremely varied production processes are used, such as the air-laid, wetlaid, spunlaced, spunbond, meltblown techniques etc. Nonwovens represent flexible porous fabrics that are not produced by the classical methods of weaving or knitting, but by intertwining and/or by cohesive and/or adhesive bonding of typical synthetic textile fibres, which may for example be present in the form of endless fibres or fibres prefabricated with an endless

length, as synthetic fibres produced in situ or in the form of staple fibres. Alternatively they may be made from natural fibres or from blends of synthetic fibres and natural fibres.

The fibrous web material according to the present invention may be toilet paper, kitchen paper, napkins, serviettes, handkerchiefs, paper towels, towels, wipes, different types of cloths, make-up removal towels, facial tissue, cosmetic tissue, baby wipes, kitchen towels, kitchen wipes, cleaning wipes, industrial wiping material or any other wiping or personal hygiene material.

Furthermore, the apparatus 1 shown in figure 1a comprises a perforation line production roll 3 provided with four perforation knives 4. However, even though four perforation knives 4 are shown in figure 1a, the perforation line production roll 3 may be provided with any suitable number of perforation knives 4, i.e. one or more perforation knives 4. The perforation knife/knives 4 provided on the perforation line production roll 3 may, for example, be helically arranged on the roll 3. Furthermore, the perforation knife/knives 4 provided on the perforation line production roll 3 may be arranged in an inclined position or in a straight position. In figure 1a the perforation knives 4 are helically arranged on the roll 3 and arranged in an inclined position. Each perforation knife 4 is arranged for providing a perforation line 18 on the fibrous web material 2 during a perforation operation. The term "perforation operation" is herein to be understood as the procedure when one perforation knife 4 produces one perforation line 18 on the fibrous web material 2. In figure 1 , the perforation line production roll 3 is arranged to rotate clockwise.

Figure 2 shows a schematic side view of one non-limiting example of the basic configuration of one perforation knife 4. The perforation knife/knives 4 provided on the perforation line production roll 3 may have any configuration that is suitable to provide a desired perforation line configuration with a certain number of perforation apertures 19, a certain number of bonded areas 20, a certain shape and size of the different perforation apertures 19, a certain shape and size of the different bonded areas 20, etc. The expression that a "perforation line has a certain perforation line configuration" is herein intended to mean that the perforation line comprises a certain number of perforation apertures 19, a certain number of bonded areas 20, a certain shape and size of the different perforation apertures 19, and a certain shape and size of the different bonded areas 20. The shape of the perforation apertures 19 in a perforation line 18 may be mutually the same or different, the size of the perforation apertures 19 in a perforation line

θ

18 may be mutually the same or different, the shape of the bonded areas 20 in a perforation line 18 may be mutually the same or different and the size of the bonded areas 20 in a perforation line 18 may be mutually the same or different. Thus, a perforation line 18 may comprise one or more repeating patterns. The perforation line configuration shown in figure 1a is a non-limiting example of a perforation line configuration.

Each perforation knife 4 provided on the perforation line production roll 3 has a plurality of teeth 5. Furthermore, each perforation knife tooth 5 comprises a perforation portion 6 arranged to produce one perforation aperture 19 during a perforation operation. Thus, the perforation portion 6 is the portion of a tooth 5 that is arranged to contact the fibrous web material 2 during a perforation operation. The perforation portion 6 of a tooth 5 may consist of the complete tooth 5 or only a part of the tooth 5. Furthermore, the perforation portion 6 comprises a peripheral surface 7, which is the surface of the perforation portion 6 that is arranged to first hit the fibrous web material 2 during a perforation operation.

Since each perforation knife 4, as mentioned above, may have any configuration that is suitable to provide a desired perforation line configuration, each perforation knife 4 may comprise any suitable number of teeth 5, may have any suitable shape and size of the different teeth 5, may have any suitable shape and size of the different areas between two consecutive teeth 5, etc. Preferably, the perforation knife/knives 4 is/are produced of a flat bar or a steel blade.

As further can be seen in figure 1a, the apparatus 1 comprises also an opposing blade carrying roll 24 provided with four opposing blades 8. However, even though four opposing blades 8 are shown in figure 1a, the opposing blade carrying roll 24 may be provided with any suitable number of opposing blades 8, i.e. one or more opposing blades 8. The opposing blade/blades 8 provided on the opposing blade carrying roll 24 may, for example, be helically arranged on the roll 24. Furthermore, the opposing blade/blades 8 provided on the roll 24 may be arranged in an inclined position or in a straight position. In figure 1a the opposing blades 8 are helically arranged on the roll 24 and arranged in an inclined position. The opposing blade carrying roll 24 is arranged on the opposite side of the fibrous web material 2 compared to the perforation line production roll 3. Thus, the fibrous web material 2 is arranged to run between the perforation line production roll 3 and the opposing blade carrying roll 24. In figure 1a the roll 24 is arranged to rotate counter clockwise. Furthermore, the arrangement of the perforation line production roll 3 and the

opposing blade carrying roll 24, the arrangement of the perforation knife/knives 4 on the roll 3 and the opposing blade/blades 8 on the roll 24 and the speed of rotation of the roll 3 and the roll 24, respectively, are adjusted such that the perforation portions 6 of each perforation knife 4 hit an opposing blade 8 during rotation of the perforation line 5 production roll 3. When the perforation portions 6 of a perforation knife 4 hit an opposing blade 8, they cut the fibrous web material 2, whereby a perforation line 18 comprising a plurality of perforation apertures 19 is produced. This will be further explained below.

Furthermore, the apparatus 1 shown in figure 1a comprises an ink application system 9 io arranged for applying a layer of an ink 10 at least partly to the perforation portion 6 of all teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. More specifically the ink application system 9 shown in figure 1a is arranged for applying a layer of an ink 10 at least partly to the peripheral surface 7 of all teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a 15 perforation operation. The ink application system 9 comprises an ink chamber 11 , an ink transfer roll 12 and an ink application roll 13.

The ink chamber 11 is arranged to hold a sufficient supply of the typically liquid ink 10. The ink 10 has a colour that contrasts with the colour of the fibrous material in the fibrous

20 web material 2. Thus, the ink 10 has such a colour that it is readily identifiable on the fibrous web material 2. As utilized herein, the term "ink" is to be understood to include pigment, tint, dye, toner, or any other colouring matter. The ink 10 may, for example, be any suitable ink normally used in production of a pattern on a fibrous web material 2. For example, the ink 10 may be a flexographic ink.

25

The ink transfer roll 12 is arranged to transfer ink 10 from the ink chamber 11 to the ink application roll 13. Therefore, the ink transfer roll 12 is arranged to contact both the ink chamber 11 and the ink application roll 13 during rotation. In figure 1a, the ink transfer roll 12 is arranged to rotate clockwise. Furthermore, the ink transfer roll 12 comprises bowl-

30 like cells 14 on its surface, which cells 14 are arranged to receive and accommodate ink 10. For example, the ink transfer roll 12 may be an anilox roll. Furthermore, the ink transfer roll 12 is arranged such that the cells 14 enter into and out of the ink chamber 11 when the ink transfer roll 12 is rotating. When the cells 14 enter into the ink chamber 11 they will take up ink 10 such that they accommodate ink 10 when leaving the ink chamber

35 11.

Furthermore, the ink transfer roll 12 and the ink application roll 13 are arranged in relation to each other such that the ink 10 introduced into the cells 14 of the ink transfer roll 12 in the ink chamber 11 will be at least partially transferred to the surface of the ink application roll 13. In figure 1a, the ink application roll 13 is arranged to rotate counter clockwise and is arranged to apply a pressure on the ink transfer roll 12. Thereby, the ink 10 accommodated in the cells 14 of the ink transfer roll 12 is at least partially transferred to the surface of the ink application roll 13 when the surface tension is released due to the pressure applied of the ink application roll 13 on the ink transfer roll 12. This provides for application of a very even layer of the ink 10 on the surface of the ink application roll 13. The materials selected for the ink transfer roll 12 and the ink application roll 13 may enhance the transfer effect. A suitable material for the ink transfer roll 12 is hard chromed steel or ceramic coated steel and a suitable material for at least the surface of the ink application roll 13 is a flexible or resilient material such as rubber.

Furthermore, in figure 1a the ink application roll 13 and the perforation line production roll 3 are arranged in relation to each other such that the perforation surface 7 of all teeth 5 of each perforation knife 4 at least partly contacts the surface of the ink application roll 13 during rotation of the perforation line production roll 3. A layer of the ink 10 will be applied at least partly to the peripheral surfaces 7 when they contact the ink application roll 13 due to that the surface of the ink application roll 13 is provided with the ink 10.

The amount of ink 10 applied to the peripheral surfaces 7 may be adjusted by adjusting the speed of rotation of the ink transfer roll 12, or by adjusting the distance between the ink transfer roll 12 and the ink application roll 13, or by adjusting the distance between the ink application roll 13 and the perforation line production roll 3, or by any combination thereof.

As mentioned above, the arrangement of the perforation line production roll 3 and the opposing blade carrying roll 24, the arrangement of the perforation knife/knives 4 on the roll 3 and the opposing blade/blades 8 on the roll 24 and the speed of rotation of the roll 3 and the roll 24, respectively, are adjusted such that the perforation portions 6 of each perforation knife 4 hit an opposing blade 8 during rotation of the perforation line production roll 3. When the perforation portions 6 of a perforation knife 4 hit an opposing blade 8 once, each perforation portion 6 produces one perforation aperture 19 in a perforation line 18 on the fibrous web material 2.

However, due to the contact with the ink application roll 13, the peripheral surface 7 of all perforation portions 6 of each perforation knife 4 will be at least partly provided with the ink 10 before the perforation portions 6 hit an opposing blade 8. Thereby, the perforation portions 6 will not only produce a perforation aperture 19 when they hit an opposing blade 8, but also transfer the ink 10 provided on their peripheral surfaces 7 at least partially to at least parts of the circumference of the respective perforation aperture 19 they produce, i.e. to at least parts of the sides or edges of the respective perforation aperture 19 they produce. Thus, the perforation apertures 19 thus produced will be at least partly encompassed by the ink 10 and are coloured such that they obtain the colour of the ink 10. The colour of the ink 10 contrasts with the colour of the fibrous material in the fibrous web material 2 and may thereby be readily seen on the fibrous web material 2. The transfer of the ink 10 will be performed when the peripheral surfaces 7 of the teeth 5 contact and pass through the fibrous web material 2.

Figure 1b shows a schematic perspective view of one variant of the apparatus 1 shown in figure 1 a, which variant also may be utilized for performing a first embodiment of the method according to the invention. The variant shown in figure 1b differs from the apparatus 1 shown in figure 1a only regarding the ink application system 9. The apparatus 1 shown in figure 1b comprises an ink application system 9 arranged for applying a layer of an ink 10 at least partly to the peripheral surface 7 of six teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. More specifically, the ink application system 9 shown in figure 1b is arranged for applying a layer of an ink 10 at least partly to the peripheral surface 7 of the three teeth 5 positioned nearest each end of each perforation knife 4. The ink application system 9 in figure 1 b differs from the ink application system 9 in figure 1a in that a circumferential recess 25 is provided on the surface of the ink application roll 13. The recess 25 on the surface of the ink application roll 13 is provided at such a position and has such a length in the length direction of the roll 13 that the peripheral surface 7 of all teeth 5, except the peripheral surface 7 of the three teeth 5 positioned nearest each end of each perforation knife 4, will enter into the recess 25 during rotation of the perforation line production roll 3.

Furthermore, the recess 25 has such a depth that the peripheral surfaces 7 entering into the recess 25 do not contact the ink application roll 13. Thereby, the peripheral surface 7 of only the three teeth 5 positioned nearest each end of each perforation knife 4 will contact the surface of the ink application roll 13 during rotation of the perforation line

production roll 3. The peripheral surface 7 of the teeth 5 positioned in a central portion of each perforation knife 4 will then not be provided with any ink 10.

When the perforation portions 6 of a perforation knife 4 in the apparatus 1 shown in figure 1b hit an opposing blade 8, all perforation portions 6 will produce a perforation aperture 19 on the fibrous web material 2, but only the six perforation portions 6 of which the peripheral surface 7 is at least partly provided with the ink 10 will produce perforation apertures 19 having a circumference at least partially provided with the ink 10.

In variants of the apparatus 1 shown in figure 1 b, the length of the recess 25 in the length direction of the ink application roll 13 and/or the position of the recess 25 on the surface of the ink application roll 13 may be changed. Furthermore, variants of the apparatus 1 shown in figure 1 b may also comprise more than one recess 25 on the surface of the ink application roll 13. Then the recesses 25 may have the same size or different sizes. Thus, in variants of the apparatus 1 shown in figure 1b, the ink application system 9 may be arranged for applying a layer of an ink 10 at least partly to the peripheral surface 7 of any desired number of teeth 5 and the teeth 5 to which peripheral surface 7 the ink 10 is applied may be located at any desired position on a perforation knife 4.

However, in all variants of the apparatuses 1 shown in figures 1a and 1b for performing the first embodiment of the method according to the invention the ink application system 9 is arranged for applying a layer of the ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. More specifically in all variants of the apparatuses 1 shown in figures 1a and 1b for performing the first embodiment of the method according to the invention the ink application system 9 is arranged for applying a layer of the ink 10 at least partly to the peripheral surface 7 of each of at least two teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. Thus, by all variants of the apparatuses 1 shown in figures 1a and 1b perforation lines 18 may be produced of which the circumference of at least two perforation portions 19 is at least partly provided with the ink 10.

Furthermore, in other variants (not shown) of any of the above described embodiments of the apparatus 1 for performing a first embodiment of the method according to the invention, the apparatus 1 comprises a fixed support instead of the opposing blade

carrying roll 24. The fixed support is then provided with one fixed opposing blade 8. The fibrous web material 2 is then arranged to run between the perforation line production roll 3 and the fixed opposing blade 8. Furthermore, each perforation knife 4 provided on the perforation line production roll 3 is then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3. More specifically, the perforation portions 6 of each perforation knife 4 are then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3.

In still other variants (not shown) of any of the above described embodiments of the apparatus 1 for performing a first embodiment of the method according to the invention, the ink application system 9 comprises a so-called chamber doctor blade system instead of the ink chamber 11. One example of a chamber doctor blade system is shown and described in WO 02/27098. The chamber doctor blade system comprises an ink reservoir holding a sufficient supply of the ink 10. The ink reservoir is connected by way of suitable conduits for the ink 10 to an inking chamber. The inking chamber, in turn, comprises one or more doctor blades. In combination, the ink reservoir, the inking chamber and the doctor blades supply the ink transfer roll 12 with the desired amount of ink 10.

According to the invention, a method is provided by which a perforation line 18 having enhanced visibility may be provided on a fibrous web material 2. The apparatus 1 shown in figure 1a or the apparatus 1 shown in figure 1b or any of the above described variants of the apparatuses 1 shown in figures 1a and 1b may be utilized for performing a first embodiment of the method according to the invention. The first embodiment of the method according to the invention for providing a perforation line 18 having enhanced visibility on a fibrous web material 2, which perforation line 18 extends transversely across the fibrous web material 2 and which perforation line 18 comprises a plurality of perforation apertures 19, comprises the steps of.

- providing a perforation knife 4 having a plurality of teeth 5, which perforation knife 4 is to be utilized for producing the perforation line 18 comprising a plurality of perforation apertures 19 on the fibrous web material 2 during a perforation operation and which perforation knife teeth 5 each comprises a perforation portion 6 arranged to produce one perforation aperture 19 during the perforation operation;

- applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 before the perforation operation

is performed, which ink 10 has a colour contrasting with the fibrous material in the fibrous web material 2, whereby the application is performed by contacting a peripheral surface 7 of the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 at least partly with an ink application roll 13 provided with a layer of the ink 10 on its surface;

- positioning the fibrous web material 2 and the perforation knife 4 in relation to each other for enabling the perforation operation to be performed at an intended location on the fibrous web material 2, and

- performing the perforation operation by perforating the fibrous web material 2 by means of the perforation knife 4, whereby the perforation line 18 comprising a plurality of perforation apertures 19 is produced and ink 10 is transferred from those perforation portions 6 provided with the ink 10 to at least parts of the circumference of the corresponding perforation apertures 19 thus produced.

The steps of the first embodiment of the method according to the invention may be repeated in order to provide a plurality of perforation lines 18 having enhanced visibility on a fibrous web material 2, which perforation lines 18 extend transversely across the fibrous web material 2 at spaced apart locations thereof. When the steps of the first embodiment of the method according to the invention are repeated a fibrous web material 2 having a plurality of perforation lines 18 with enhanced visibility is produced. Such a fibrous web material 2 is divided into a plurality of sheets by the perforation lines 18.

Figure 3 shows a schematic side view of one example of an apparatus 1 for performing a second embodiment of the method according to the invention. The apparatus 1 may be utilized for providing one or more perforation lines 18 having enhanced visibility on a fibrous web material 2, whereby each perforation line 18 extends transversely across the fibrous web material 2 and whereby each perforation line 18 comprises a plurality of perforation apertures 19. The apparatus 1 shown in figure 3 differs from the apparatuses 1 shown in figures 1a and 1b only regarding the ink application system 9. Thus, the perforation line production roll 3, the perforation knife/knives 4, the opposing blade carrying roll 24, the opposing blades 8 and the ink 10 correspond to those elements in the apparatuses 1 shown in figures 1a and 1b and the fibrous web material 2 is arranged to run between the perforation line production roll 3 and the opposing blade carrying roll 24. However, in the apparatus 1 shown in figure 3, the perforation knife/knives 4 provided on the perforation line production roll 3 is/are not arranged to contact an ink application roll

during rotation of the perforation line production roll 3 as in the apparatuses 1 in figures 1a and 1b.

The ink application system 9 in the apparatus 1 shown in figure 3 is arranged for applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. In the apparatus 1 shown in figure 3, the ink application system 9 comprises an ink chamber 11 and a spray nozzle 15. The ink chamber 11 is arranged to hold a sufficient supply of the ink 10. Furthermore, the ink chamber 11 is arranged to be connected to the spray nozzle 15. For example, the ink chamber 11 may be connected by way of suitable conduits to the spray nozzle 15. However, the spray nozzle 15 may alternatively be an integral part of the ink chamber 11.

The spray nozzle 15 is arranged for applying a layer of the ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a perforation operation. More specifically, the spray nozzle 15 is arranged for spraying the ink 10 onto at least parts of the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4. Furthermore, the spray nozzle 15 is preferably controlled by a software signal coordinated with the rotation of the perforation line production roll 3. Thereby, the spray nozzle 15 may be controlled to only spray ink 10 from the ink chamber 11 when a perforation knife 4 during rotation of the perforation line production roll 3 is in a position in relation to the spray nozzle 15 such that the ink 10 sprayed by the spray nozzle 15 is applied on the desired perforation portions 6 and not on any other elements. Thus, by controlling the spraying of the spray nozzle 15 it may be avoided that ink 10 is sprayed onto undesired elements.

Due to the application of the ink 10 by the spray nozzle 15, at least parts of the perforation portion 6 of at least two teeth 5 of each perforation knife 4 will be provided with the ink 10 before the perforation portions 6 hit an opposing blade 8. Thereby, those perforation portions 6 provided with the ink 10 will not only produce a perforation aperture 19 when they hit an opposing blade 8, but also transfer the ink 10 at least partially to at least parts of the circumference of the respective perforation aperture 19 they produce. The transfer of the ink 10 will be performed when the perforation portions 6 contact the fibrous web material 2.

The spray nozzle 15 may be arranged to spray the ink 10 onto at least parts of the perforation portion 6 of any desired number of teeth 5 (two or more) of each perforation knife 4. Thus, by the apparatus 1 shown in figure 3 perforation lines 18 may be produced on a fibrous web material 2, whereby the circumference of at least two perforation portions 19 is at least partly provided with the ink 10. For example the spray nozzle 15 may be arranged to spray the ink 10 onto at least parts of the perforation portion 6 of all teeth 5 of each perforation knife 4 or onto at least parts of the perforation portion 6 of only the teeth 5 positioned nearest the two ends of each perforation knife 4.

Furthermore, in a variant (not shown) of the apparatus 1 shown in figure 3 for performing a second embodiment of the method according to the invention, the apparatus 1 comprises a fixed support instead of the opposing blade carrying roll 24. The fixed support is then provided with one opposing blade 8. The fibrous web material 2 is then arranged to run between the perforation line production roll 3 and the fixed opposing blade 8. Furthermore, each perforation knife 4 provided on the perforation line production roll 3 is then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3. More specifically, the perforation portions 6 of each perforation knife 4 are then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3.

The apparatus 1 shown in figure 3 or the above described variants thereof may be utilized for performing a second embodiment of the method according to the invention. The second embodiment of the method according to the invention for providing a perforation line 18 having enhanced visibility on a fibrous web material 2, which perforation line 18 extends transversely across the fibrous web material 2 and which perforation line 18 comprises a plurality of perforation apertures 19, comprises the steps of:

- providing a perforation knife 4 having a plurality of teeth 5, which perforation knife 4 is to be utilized for producing the perforation line 18 comprising a plurality of perforation apertures 19 on the fibrous web material 2 during a perforation operation and which perforation knife teeth 5 each comprises a perforation portion 6 arranged to produce one perforation aperture 19 during the perforation operation;

- applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 before the perforation operation is performed, which ink 10 has a colour contrasting with the fibrous material in

the fibrous web material 2, whereby the application is performed by spraying the ink 10 onto at least parts of the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 by means of a spray nozzle 15;

- positioning the fibrous web material 2 and the perforation knife 4 in relation to each other for enabling the perforation operation to be performed at an intended location on the fibrous web material 2, and

- performing the perforation operation by perforating the fibrous web material 2 by means of the perforation knife 4, whereby the perforation line 18 comprising a plurality of perforation apertures 19 is produced and ink 10 is transferred from those perforation portions 6 provided with the ink 10 to at least parts of the circumference of the corresponding perforation apertures 19 thus produced.

The steps of the second embodiment of the method according to the invention may be repeated in order to provide a plurality of perforation lines 18 having enhanced visibility on a fibrous web material 2, which perforation lines 18 extend transversely across the fibrous web material 2 at spaced apart locations thereof.

Figure 4 shows a schematic side view of one example of an apparatus 1 for performing a third embodiment of the method according to the invention. The apparatus 1 may be utilized for providing one or more perforation lines 18 having enhanced visibility on a fibrous web material 2, whereby each perforation line 18 extends transversely across the fibrous web material 2 and whereby each perforation line 18 comprises a plurality of perforation apertures 19. The apparatus 1 shown in figure 4 differs from the apparatus 1 shown in figure 3 only regarding the ink application system 9. Thus, the perforation line production roll 3, the perforation knife/knives 4, the opposing blade carrying roll 24, the opposing blades 8 and the ink 10 correspond to those elements in the apparatus 1 shown in figure 3 and the fibrous web material 2 is arranged to run between the perforation line production roll 3 and the opposing blade carrying roll 24. However, in the apparatus 1 shown in figure 4, the ink application system 9 does not comprise a spray nozzle connected to an ink chamber as the ink application system 9 in the apparatus 1 shown in figure 3.

The ink application system 9 in the apparatus 1 shown in figure 4 is arranged for applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 before the respective perforation knife 4 is to perform a

perforation operation. For example the ink application system 9 may be arranged for applying a layer of the ink 10 at least partly to the perforation portion 6 of all teeth 5 of each perforation knife 4 or to the perforation portion 6 of only the teeth 5 positioned nearest the two ends of each perforation knife 4. In the apparatus 1 shown in figure 4, the ink application system 9 comprises an ink chamber 11 and an ink stamp unit 16. The ink chamber 11 is arranged to hold a sufficient supply of the ink 10 and comprises a valve 17 by which the ink 10 is dropped onto the ink stamp unit 16 in a controlled manner. The valve 17 may be an integral part of the ink chamber 11 or a separate element to which the ink chamber 11 is connected. The ink stamp unit 16 may be a felt member filled with the ^' ink 10 or a brush of fibres filled with the ink 10. The ink stamp unit 16 may be arranged to rotate, as in figure 4, or may alternatively be fixed.

Furthermore, in the apparatus 1 shown in figure 4 each perforation knife 4 provided on the perforation line production roll 3 is arranged to contact the ink stamp unit 16 during rotation of the perforation line production roll 3. More specifically, the peripheral surface 7 of the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 is arranged to at least partly contact the surface of the ink stamp unit 16 during rotation of the perforation line production roll 3. A layer of the ink 10 will be applied at least partly to those peripheral surfaces 7 contacting the ink stamp unit 16.

In an alternative (not shown) of the apparatus 1 shown in figure 4, the peripheral surface 7 and at least parts of the rest of the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4 are arranged to enter into the ink stamp unit 16 during rotation of the perforation line production roll 3. A layer of the ink 10 will then be applied at least partly to the peripheral surface 7 and at least partly to at least parts of the rest of the perforation portion 6 of each of at least two teeth 5 of each perforation knife 4.

In any of the above described variants of the apparatus 1 shown in figure 4, the length of the ink stamp unit 16 in the length direction of the perforation line production roll 3 may be varied, whereby different numbers of teeth 5 may be provided with the ink 10.

Furthermore, if the length of the ink stamp unit 16 in the length direction of the perforation line production roll 3 is smaller than the length of the perforation knife/knives 4, the position of the ink stamp unit 16 in the length direction of the perforation line production roll 3 may also be varied. In addition, instead of one ink stamp unit 16, the ink application system 9 may comprise more than one ink stamp unit 16. For example, the ink application

system 9 may comprise one ink stamp unit 16 arranged such that the peripheral surface 7 of the tooth 5 nearest one end of each perforation knife 4 contacts the ink stamp unit 16 and another ink stamp unit 16 arranged such that the peripheral surface 7 of the tooth 5 nearest the other end of each perforation knife 4 contacts that ink stamp unit 16.

Furthermore, in variants (not shown) of any of the above described variants of the apparatus 1 shown in figure 4 for performing a third embodiment of the method according to the invention, the apparatus 1 comprises a fixed support instead of the opposing blade carrying roll 24. The fixed support is then provided with one fixed opposing blade 8. The fibrous web material 2 is then arranged to run between the perforation line production roll 3 and the fixed opposing blade 8. Furthermore, each perforation knife 4 provided on the perforation line production roll 3 is then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3. More specifically, the perforation portions 6 of each perforation knife 4 are then arranged to hit the fixed opposing blade 8 during rotation of the perforation line production roll 3.

The apparatus 1 shown in figure 4 may be utilized for performing a third embodiment of the method according to the invention. The third embodiment of the method according to the invention for providing a perforation line 18 having enhanced visibility on a fibrous web material 2, which perforation line 18 extends transversely across the fibrous web material 2 and which perforation line 18 comprises a plurality of perforation apertures 19, comprises the steps of:

- providing a perforation knife 4 having a plurality of teeth 5, which perforation knife 4 is to be utilized for producing the perforation line 18 comprising a plurality of perforation apertures 19 on the fibrous web material 2 during a perforation operation and which perforation knife teeth 5 each comprises a perforation portion 6 arranged to produce one perforation aperture 19 during the perforation operation;

- applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 before the perforation operation is performed, which ink 10 has a colour contrasting with the fibrous material in the fibrous web material 2, whereby the application is performed by contacting at least parts of the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 with an ink stamp unit 16;

- positioning the fibrous web material 2 and the perforation knife 4 in relation to each other for enabling the perforation operation to be performed at an intended location on the fibrous web material 2, and

- performing the perforation operation by perforating the fibrous web material 2 by means of the perforation knife 4, whereby the perforation line 18 comprising a plurality of perforation apertures 19 is produced and ink 10 is transferred from those perforation portions 6 provided with the ink 10 to at least parts of the circumference of the corresponding perforation apertures 19 thus produced.

The steps of the third embodiment of the method according to the invention may be repeated in order to provide a plurality of perforation lines 18 having enhanced visibility on a fibrous web material 2, which perforation lines 18 extend transversely across the fibrous web material 2 at spaced apart locations thereof.

The step of applying a layer of an ink 10 at least partly to the perforation portion 6 of each of at least two teeth 5 of the perforation knife 4 may in any of the embodiments of the method according to the invention comprise applying a layer of the ink 10 at least partly to the perforation portion 6 of any suitable number of teeth 5 of the perforation knife 4. For example, that step may comprise applying a layer of the ink 10 at least partly to the perforation portion 6 of all teeth 5 of the perforation knife 4. Furthermore, it may also, for example, comprise applying a layer of the ink 10 at least partly to the perforation portion 6 of at least two teeth 5 of the perforation knife 4, whereby a layer of the ink 10 is applied at least partly to the perforation portion 6 of those teeth 5 positioned nearest the two ends of the perforation knife 4 while no ink 10 is applied to the teeth 5 in the central portion of the perforation knife 4.

By utilizing the method according to the invention, one or more perforation lines having enhanced visibility may be achieved on a fibrous web material. The production of the enhanced visibility of a perforation line is in the method according to the invention achieved by colouring at least two perforation apertures of the perforation line at the same time as the perforation line is produced. Thus, no extra production step is required for achieving an enhanced visibility of a perforation line on a fibrous web material when the method according to the invention is utilized. Furthermore, when comparing the method according to the invention to a method in which a perforation line is produced in one production step and a marker identifying the perforation line is produced in a subsequent

production step by, for example, printing, there are several advantages with the method according to the invention. For example, when performing the method according to the invention no extra process equipment for printing a marker onto the fibrous web material is required. Furthermore, when the method according to the invention is utilized, the exact position of a perforation line is marked since the perforation line is marked through colouring at the same time as it is produced. The risk that a position on the fibrous web material is marked that does not comprise a perforation line does not exist when the method according to the invention is utilized. As mentioned above, that risk exists when a perforation line is produced in one production step and the marker is added in a subsequent production step. Furthermore, the method according to the invention is simpler and may result in less expensive production.

The specific directions of rotation shown in figures 1 , 3 and 4 for the perforation line production roll 3, the ink transfer roll 12, the ink application roll 13 and the opposing blade carrying roll 24 are non-limiting examples of directions of rotation. It should be apparent for a person skilled in the art that the perforation line production roll 3, the ink transfer roll 12, the ink application roll 13 and the opposing blade carrying roll 24 may be arranged to rotate in any desired and suitable directions. For example, all directions of rotation could be opposed. Furthermore, the direction that the fibrous web material 2 shown in figures 1 , 3 and 4 runs in is also a non-limiting example. Thus, the fibrous web material 2 may be arranged to run in any desired direction in the apparatus 1.

Figures 5-7 illustrate three different embodiments of a fibrous web material 2 according to the invention. The fibrous web material 2 according to the invention may be obtained by utilizing the method according to the invention or any other suitable method yielding the same result.

Figure 5 illustrates a first embodiment of the fibrous web material 2 according to the invention, which may be obtained by repeating the steps of any of the above described embodiments of the method according to the invention or by any other suitable method yielding the same result. The first embodiment of the fibrous web material 2 according to the invention comprises a plurality of perforation lines 18. Each perforation line 18 extends transversely across the fibrous web material 2 and comprises a plurality of perforation apertures 19. Between each pair of two consecutive perforation apertures 19 in a perforation line 18 there is a bonded area 20. The perforation lines 18 are provided at

spaced apart locations and are typically provided at regular intervals. Thus, the perforation lines 18 divide the fibrous web material 2 in the length direction into a plurality of individual sheets 21 , which are removable for use.

Furthermore, the visibility of the perforation lines 18 on the fibrous web material 2 shown in figure 5 is enhanced due to that the circumference of all perforation apertures 19 in each perforation line 18 is at least partly provided with the an ink 10 having a colour contrasting with the fibrous material in the fibrous web material 2, i.e. the sides or edges of all perforation apertures 19 in each perforation line 18 are at least partly provided with the ink 10. Thus, all perforation apertures 19 in each perforation line 18 are at least partly encompassed by the ink 10 and are thereby coloured with the ink 10. Since the ink 10 has a colour contrasting with the fibrous material in the fibrous web material 2, the perforation apertures 19 may be readily seen on the fibrous web material 2.

The colouring of the perforation apertures 19 allows easy identification of the perforation lines 18. Furthermore, identification of the perforation lines 18 in low light conditions is promoted. Identification of the perforation lines 18 by visually handicapped people is also promoted. Thus, the colouring of the perforation apertures 19 promotes usage of the perforation lines 18 when pieces are to be torn off from the fibrous web material 2. Thereby, the risk for unnecessary waste, the risk for resulting irregular edges on a piece torn off from the fibrous web material 2 and on the remainder of the fibrous web material 2, and the risk for that a user grips both a piece to be torn off and the remainder of the fibrous web material 2, as above mentioned, are reduced. Furthermore, the length of the sheets 21 is typically adjusted to be sufficient for one wiping situation. When identification of the perforation lines 18 is promoted, usage of intact sheets 21 is promoted.

Furthermore, even if a specific perforation line configuration is shown in figure 5, the perforation lines 18 may have any suitable configuration. Thereby, each perforation line 18 may comprise any suitable number of perforation apertures 19, any suitable number of bonded areas 20, any suitable shape and size of each perforation aperture 19 and any suitable shape and size of each bonded area 20. Furthermore, the shape of the perforation apertures 19 in a perforation line 18 may be mutually the same or different, the size of the perforation apertures 19 in a perforation line 18 may be mutually the same or different, the shape of the bonded areas 20 in a perforation line 18 may be mutually the same or different, and the size of the bonded areas 20 in a perforation line 18 may be

mutually the same or different. Thus, the perforation lines 18 may comprise one or more repeating patterns.

The fibrous web material 2 shown in figure 5 is rolled and comprised in a rolled product 22.

Figure 6 illustrates a second embodiment of the fibrous web material 2 according to the invention, which may be obtained by repeating the steps of any of the above described embodiments of the method according to the invention or by any other suitable method yielding the same result. The second embodiment of the fibrous web material 2 corresponds to the first embodiment of the fibrous web material 2 shown in figure 5 except for that the circumference of only some perforation apertures 19, instead of all perforation apertures 19, in each perforation line 18 is at least partly provided with the ink 10. In the second embodiment of the fibrous web material 2, the circumference of those perforation apertures 19 positioned nearest the two ends of each perforation line 18 is at least partly provided with the ink 10 while those perforation apertures 19 in the central portion of each perforation line 18 are free from ink 10.

Figure 7 illustrates a third embodiment of the fibrous web material 2 according to the invention, which may be obtained by repeating the steps of any of the above described embodiments of the method according to the invention or by any other suitable method yielding the same result. The third embodiment of the fibrous web material 2 corresponds to the second embodiment except for that the circumference of two perforation apertures 19 in the central portion of each perforation line 18 is provided with the ink 10 instead of those perforation apertures 19 positioned nearest the two ends of each perforation line 18. Furthermore, the third embodiment of the fibrous web material 2 is folded instead of rolled.

A fourth embodiment (not shown) of the fibrous web material 2 corresponds to the third embodiment of the fibrous web material 2 except for that all perforation apertures 19 in each perforation line 18 are provided with the ink 10.

In a fibrous web material 2 according to the invention, the circumference of any suitable number (more than one) of perforation apertures 19 in each perforation line 18 may be at least partly provided with the ink 10. Thus, in variants of the embodiments mentioned above, the number of perforation apertures 19 whose circumference is at least partly provided with the ink 10 is varied.

Furthermore, a fibrous web material 2 according to the invention may alternatively only comprise one perforation line 18 extending transversely across the fibrous web material 2. The circumference of any suitable number (more than one) of perforation apertures 19 in the perforation line 18 may then be at least partly provided with the ink 10. Such a fibrous web material 2 may be produced by performing the steps of any of the embodiments of the method according to the invention only once or by any other method yielding the same result.

More specifically, a fibrous web material 2 according to the invention comprises at least one perforation line 18, whereby each perforation line 18 extends transversely across the fibrous web material 2 and whereby each perforation line 18 comprises a plurality of perforation apertures 19. The circumference of at least two perforation apertures 19 in each perforation line 18 is at least partly provided with the ink 10 having a colour contrasting with the fibrous material in the fibrous web material 2. Protection is sought for such fibrous web materials 2 being produced by means of the method according to the invention or by means of any other suitable method yielding the same result.

Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices, method steps and products illustrated may be made by those skilled in the art. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.