METHOD AND EXTRUSION DIE FOR MAKING A STRUCTURING FABRIC

Abstract

An extrusion die makes a structuring fabric which has structuring-beads resting on sublayer-beads. The extrusion die has a flat first surface and a flat second surface, the first and second surfaces contact each other along a contact line. The first and second surfaces are inclined with respect to each other. The first surface has a first nozzle of a pair of nozzles for extruding a sublayer-bead and the second surface has a second nozzle of the pair of nozzles for extruding a structuring-bead on top of the sublayer-bead. The first nozzle has a substantially rectangular shape and the second nozzle has a shape that resembles a square with all four side edges bulged inwardly. Both the first nozzle and the second nozzle are located in close proximity to the contact line. The first nozzle has a first symmetry axis that is perpendicular to the contact line.

Claims

1. An extrusion die for making a structuring fabric having structuring-beads resting on sublayer-beads, the extrusion die comprising: a substantially flat first surface; and a substantially flat second surface, said substantially flat first surface and said substantially flat second surface contact each other along a contact line and said substantially flat first surface and said substantially flat second surface are inclined with respect to each other, wherein said substantially flat first surface contains a first nozzle of a pair of nozzles for extruding a sublayer-bead and wherein said substantially flat second surface contains a second nozzle of said pair of nozzles for extruding a structuring-bead on top of said sublayer-bead, wherein said substantially flat first nozzle has a substantially rectangular shape and wherein said substantially flat second nozzle has a shape that resembles a square with all four side edges bulged inwardly, wherein both, said first nozzle and said second nozzle are disposed in close proximity to said contact line, wherein said first nozzle has a first symmetry axis that is perpendicular to said contact line, and wherein said second nozzle has a second symmetry axis that is perpendicular to said contact line, wherein the first symmetry axis and the second symmetry axis contact each other at said contact line.

2. The extrusion die according to claim 1, wherein a distance of said first nozzle to said contact line is smaller than 10% of a dimension of said first nozzle measured along the first symmetry axis and/or wherein a distance of said second nozzle to said contact line is smaller than 10% of a dimension of said second nozzle measured along the second symmetry axis.

3. The extrusion die according to claim 1, wherein said first nozzle has a third symmetry axis that is parallel to said contact line and wherein said second nozzle has a fourth symmetry axis that is parallel to said contact line.

4. The extrusion die according to claim 3, wherein a dimension of said first nozzle measured along the third symmetry axis substantially corresponds to a dimension of said second nozzle measured along the fourth symmetry axis.

5. The extrusion die according to claim 1, wherein a dimension of said first nozzle measured along the first symmetry axis substantially corresponds to a half of a dimension of said second nozzle measured along the second symmetry axis.

6. The extrusion die according to claim 1, wherein a dimension of said second nozzle measured along the second symmetry axis is between 60% and 80% of a largest dimension of said second nozzle measured along a line that is parallel to the second symmetry axis.

7. The extrusion die according to claim 1, further comprising a plurality of equally formed pairs of nozzles that are distributed along said contact line.

8. The extrusion die according to claim 1, further comprising a common supply chamber, said first nozzle and said second nozzle are connected to said common supply chamber within the extrusion die so as supply a same material to both said first and second nozzles.

9. A method of producing a structured fabric having at least one structuring-bead resting on at least one sublayer-bead, the method comprises the following steps of: a) providing the extrusion die according to claim 1; b) providing a woven base fabric, the woven base fabric having a web facing side and a machine side; c) extruding a sublayer-bead of polymeric material through the first nozzle of the extrusion die onto the web facing surface of the woven base fabric, wherein the sublayer-bead contains an upper foundation surface; and d) extruding a structuring-bead of polymeric material through the second nozzle of the extrusion die onto a top of the upper foundation surface of the sublayer-bead.

10. The production method according to claim 9, wherein the woven base fabric contains an upper layer defining the web facing side of the woven base fabric, wherein the upper layer is formed from upper cross-machine direction yarns that are interwoven with upper machine direction yarns, and wherein the sublayer-bead extends so deeply into the woven base fabric that the sublayer-bead creates a form-fit connection with at least some of the upper cross-machine direction yarns at their deepest points.

11. The production method according to claim 9, wherein the substantially flat first surface of the extrusion die is substantially parallel to the web facing surface of the woven fabric during an extrusion process and wherein the substantially flat second surface of the extrusion die is inclined with respect to the web facing surface of the woven fabric during the extrusion process.

12. The production method according to claim 9, wherein a distance of the first nozzle to the web facing surface of the woven fabric is larger than a distance of the second nozzle to the web facing surface of the woven fabric during an extrusion process.

13. The production method according to claim 9, wherein the structuring-bead is extruded in step d) at a time when the sublayer-bead has not been cured yet.

14. The production method according to claim 9, wherein a form of the upper foundation surface of the sublayer-bead substantially corresponds to a form of a lower surface of the structuring bead that rest thereon.

15. The production method according to claim 9, wherein the upper foundation surface of the sublayer-bead is substantially flat.

16. The production method according to claim 9, wherein in a thickness direction of the structured fabric, the sublayer-bead is provided substantially within a volume of the woven base fabric.

17. The production method according to claim 9, wherein the structuring-bead forms a continuous line on the web facing surface of the woven base fabric.

18. The production method according to claim 9, wherein the structuring-bead forms a straight line on the web facing surface of the woven base fabric or the structuring-bead has a wavy configuration.

19. The production method according to claim 9, wherein the polymeric material extruded through the first nozzle to form the sublayer-bead and/or the polymeric material extruded through the second nozzle to form the structuring-bead is a silicone.

20. The production method according to claim 9, wherein the polymeric material extruded through the first nozzle to form the sublayer-bead and/or the polymeric material extruded through the second nozzle to form the structuring-bead is a polyurethane.

21. The production method according to claim 9, wherein the polymeric material extruded through the first nozzle to form the sublayer-bead and/or the polymeric material extruded through the second nozzle to form the structuring-bead is an acrylic material.

22. The production method according to claim 21, wherein the acrylic material comprises at least one of the following components: N,N-Dimethylacrylamide; 2-Propenoic acid, 2-hydroxyethyl ester, polymer with 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane; Isobornyl acrylate; 2-(2-Ethoxyethoxy)ethyl acrylate; diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane; acrylic acid; and 2-Hydroxyethyl acrylate.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0048] FIG. 1A is an illustration showing two extrusion dies according to the prior art;

[0049] FIG. 1B is a cross-sectional view of a portion of a structuring fabric known from the prior art;

[0050] FIG. 2 is an illustration showing an extrusion die according to the invention, with several pairs of first and second nozzles to extrude sublayer-beads and corresponding structuring-beads on top thereof;

[0051] FIG. 3 is an illustration showing a manufacturing process for producing the structuring fabric by using the extrusion die according to the present invention; and

[0052] FIG. 4 is a cross-sectional view of a portion of the structuring fabric produced with the extrusion die according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0053] Referring now to the figures of the drawings in detail and first, particularly to FIG. 2 thereof, there is shown an extrusion die 22 according to the present invention and adapted to simultaneously apply several structuring-beads 14 and corresponding sublayer-beads 20 onto a web facing side 16 of a woven base fabric 12 (see FIG. 4). More precisely, the extrusion die 22 contains five pairs of first nozzles 24 and second nozzles 26, to extrude five pairs of sublayer-beads 20 and structuring-beads 14, respectively. For the sake of clarity, two pairs of first nozzles 24 and second nozzles 26 are shown in an enlarged view on the bottom of FIG. 2. The first nozzles 24 for extruding the sublayer-beads 20 have a substantially rectangular form, whereas the second nozzles 26 for extruding the structuring-beads 14 have a shape that resembles a square with all four side edges bulged inwardly. The smallest distance between two opposite inwardly bulged side edges is designated here with letter A. This smallest distance A is preferably between 0.3 mm and 1.0 mm, more preferably between 0.6 mm and 0.8 mm. The first, substantially rectangular shaped nozzle 24 has a width that substantially corresponds to the smallest distance A of the second nozzle 26. The length of the first, substantially rectangular shaped nozzle 24 is significantly smaller than its width. It is substantially only half of the width, i.e. half the smallest distance A of the second nozzle 26.

[0054] The pitch of two directly neighboring pairs of first nozzles 24 and second nozzles 26 is B. The pitch B is measured as the distance from the center of one second nozzle 26 to the center of one of its directly neighboring second nozzles 26. The pitch B is preferably between 2 and 6 times the smallest distance A between two opposite curved lateral edges of the first, substantially rectangular shaped nozzle 24.

[0055] The first nozzles 24 are provided within a substantially flat first surface 28, whereas the second nozzles 26 are provided within a substantially flat second surface 30. The first surface 28 and the second surface 30 do not lie within the same plane. In other words, the second surface 30 is inclined with respect to the first surface 28. The first surface 28 and the second surface 30 contact each other along a contact line 36. The first nozzles 24 and the second nozzles 26 are both in close proximity to the contact line 36 without touching each other.

[0056] As shown in FIG. 3, during the manufacturing process of the structuring fabric 10, the first surface 28 of the extrusion die 22 is placed close and substantially parallel to the web facing side 16 of the woven base fabric 12. This allows resinous material extruded through the first nozzles 24 to easily penetrate the volume of the woven base fabric 12, so as to form sublayer-beads when the woven base fabric 12 is carried in moving direction v, preferably corresponding to the machine direction MD of the structuring fabric 10, below the extrusion die 22.

[0057] The resinous material extruded through the second nozzles 26 formed in the second surface 30 of the extrusion die 22 then forms the structuring-beads 14 that rest upon the upper foundation surface of the corresponding sublayer-beads 20. The inclination of the second surface 30 with respect to the first surface 28 and, thus, with respect to the web facing side 16 of the woven base fabric, helps to form substantially square shaped structuring-beads 14. The close proximity of the first nozzle 24 and the second nozzle 26 results in a very small gap 38 between the sublayer-bead 20 and the structuring-bead 14. Thus, little or even no air will be trapped between the two beads 20, 14, resulting in a very good bonding.

[0058] During the manufacturing process of the structuring fabric 10, the extrusion die 22 may be stationary while the woven base fabric 12 moves in moving direction v, so as to form a pattern of structuring-beads 14 that extend in parallel straight lines. However, if it is preferred to provide the structuring fabric 10 with another pattern of structuring-beads 14, such as a zig-zag pattern or a wavy pattern, the extrusion die 22 may be moved, e.g. back and forth, orthogonally to the moving direction v during the manufacturing process, i.e. orthogonally to the image plane of FIG. 3.

[0059] FIG. 4 shows in cross-section a portion of a structuring fabric 10 manufactured with an extrusion die 22 according to the present invention. FIG. 4 resembles FIG. 1B showing a corresponding portion of a structuring fabric known from the prior art, as described above. Therefore, the same reference signs are used for the same features, and it is referred to the description of FIG. 1B above regarding these features. In the following, only the differences between the embodiments of FIG. 1B and FIG. 4 will be explained.

[0060] In contrast to the prior-art embodiment of FIG. 1B, in the embodiment of FIG. 4, the structuring-bead 14 does not only have a limited local contact with the yarn knuckles that characterize the web facing side 16 of the woven base fabric 12 but the structuring-bead 14 rests with its lower surface on an upper foundation surface of a sublayer-bead 20. The sublayer-bead 20 is formed preferably completely within the volume of the woven base layer 12, thus having a strong bond to the woven base layer 12. Its upper foundation surface, i.e. its surface that is facing away from the machine side 18 of the woven base layer 12, is substantially flat, thereby providing a very good foundation for the structuring bead 14 resting thereon. In thickness direction TD of the structuring fabric 10, the dimension of the sublayer-bead 20 may be smaller than the dimension of the structuring-bead 14. In the present embodiment, the woven base fabric 12 is formed as a multi-layer woven fabric but it could also be a single-layer woven fabric. The upper layer, that defines the web facing side 16 of the woven base fabric 12 is preferably a plain weave. The upper layer is formed by upper machine direction yarns 32 interwoven with upper cross-machine direction yarns 34. The sublayer-bead 20 extends so deep into the woven base fabric 12 as to create a form-fit connection with the upper cross-machine direction yarns 34 where these upper cross-machine direction yarns 34 pass under the machine direction yarns 34. In other words, the polymeric material of the sublayer-bead 20 surrounds more than half of the diameter of the upper cross-machine direction yarns 34 at their lowest points. At the same time, the sublayer-bead 20 does not extend deeper into the woven base fabric 12 than the thickness of the upper layer. In thickness direction, the sublayer-bead 20 is almost as thick as the structuring-bead 14 resting thereon.

[0061] In the present embodiment, the knuckles on the web facing side 16 of the woven fabric only slightly project above the substantially flat upper foundation surface of the sublayer-bead 20. The sublayer-bead 20 and the structuring-bead 14 are preferably formed from the same polymeric material, such as a two-component silicone. This results in a strong bond between the two beads, especially if the structuring-bead 14 is applied on top of the sublayer-bead 20 at a time when the material of the sublayer-bead 20 has not been cured yet.

[0062] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention.

REFERENCE SIGNS

[0063] 10 structuring fabric [0064] 12 woven base fabric [0065] 14 structuring-bead [0066] 16 web facing side [0067] 18 machine side [0068] 20 sublayer-bead [0069] 22 extrusion die [0070] 24 first nozzle [0071] 26 second nozzle [0072] 28 first surface [0073] 30 second surface [0074] 32 upper machine direction yarns [0075] 34 upper cross-machine direction yarns [0076] 36 contact line [0077] 38 gap [0078] A smallest distance between two opposite curved lateral edges [0079] B pitch of two directly neighboring pairs of first and second nozzles [0080] CD cross machine direction [0081] MD machine direction [0082] TD thickness direction [0083] v moving direction