METHOD FOR MAKING LEATHER LAMINATE HAVING TEXTURED SURFACE

Abstract

The present invention relates to a method for making a leather laminate having a textured surface, and leather laminates made by this method. The laminates comprise a leather layer bonded to a reinforcing fabric with an adhesive, the reinforcing fabric providing strength to the laminate. The method involves dry milling the laminate in humid air, during which the reinforcing fabric constrains the laminate causing the textured surface to form.

Claims

1. A method for making a leather laminate, the method comprising: providing a piece of leather having a first side and a second side; laminating a reinforcing fabric comprising high strength fibres to the first side of the piece of leather to provide a leather laminate comprising, in order, the reinforcing fabric, an adhesive and the piece of leather; and exposing the leather laminate to water and dry milling the leather laminate to form a milled leather laminate.

2. The method of claim 1, wherein the reinforcing fabric has an elongation at break of less than 5%.

3. The method of claim 1, wherein the reinforcing fabric has an ultimate tensile strength of above 5 kN/m.

4. The method of claim 1, wherein the reinforcing fabric comprises at least one layer having parallel high strength fibres, optionally embedded in a resin matrix.

5. The method of claim 1, wherein laminating the reinforcing fabric comprises: applying an adhesive on the first side of the piece of leather; and contacting a reinforcing fabric with the adhesive.

6. The method of claim 5, wherein laminating the reinforcing fabric further comprises: applying the adhesive to the first side of the piece of leather as a spray.

7. The method of claim 1, wherein the piece of leather is a top grain leather.

8. The method of claim 1, wherein the piece of leather is a nubuck leather.

9. The method of claim 1, wherein forming the milled leather laminate comprises dry milling the leather laminate in humid air to form the milled leather laminate.

10. The method of claim 9, wherein the humid air has a relative humidity of at least 75%.

11. The method of claim 1, wherein forming the milled leather laminate comprises: soaking the leather laminate in a solution comprising water, and dry milling the soaked leather laminate to form the milled leather laminate.

12. The method of claim 1, wherein the dry milling is carried out at a temperature of from 30 to 50 C.

13. A leather laminate comprising a piece of leather having a first side and a second side; and a reinforcing fabric comprising high strength fibres laminated to the first side of the piece of leather to provide a leather laminate comprising, in order, the reinforcing fabric, an adhesive and the piece of leather; wherein the leather laminate is exposed to water and dry milled to form a milled leather laminate.

14. A leather laminate comprising a reinforcing fabric bonded to a leather layer, said reinforcing fabric comprising high strength fibres and having an elongation at break of less than 5%, wherein the leather laminate has an elongation at break of more than 5%.

15. The leather laminate of claim 14, wherein the reinforcing fabric has an elongation at break of less than 4%, and wherein the leather laminate has an elongation at break of more than 6%.

16. The leather laminate of claim 14, wherein the reinforcing fabric has an ultimate tensile strength of above 5 kN/m.

17. The leather laminate of claim 14, wherein the leather laminate has a thickness of from 0.3 to 2 mm.

18. The leather laminate of claim 14, wherein the leather layer is top grain leather, with a flesh side of the leather being bonded to the reinforcing layer.

19. The leather laminate of claim 18, wherein the leather layer is nubuck leather.

20. The leather laminate of claim 14, wherein the surface of the leather layer has a non-uniform, pebbled grain-like structure.

21. (canceled)

22. The method of claim 5, further comprising: allowing the adhesive to soak into the leather for 1 to 30 minutes.

23. The method of claim 5, further comprising: contacting the reinforcing fabric with the adhesive to form a multilayer structure comprising a layer of the reinforcing fabric, a layer of the adhesive, and the leather.

24. The method of claim 23, further comprising: applying heat or pressure to the multilayer structure by passing the multilayer structure through a nip of a heated roller.

25. The method of claim 5, further comprising: allowing the adhesive to dry for at least 1 hour.

26. The leather laminate of claim 14, wherein the reinforcing fabric comprises at least one layer having parallel high strength fibres, optionally embedded in a resin matrix.

Description

EXAMPLE 1

[0183] A 1 mm thick sample of top grain leather was skin side down and the flesh side was sprayed with adhesive. The adhesive was left to dry for 20 minutes, then Dyneema CTM2H2 fabric was placed on the adhesive. The resulting laminate was passed through a Rotopress machine having a metal roller heated to 110 C. and a felt roller with the felt roller in contact with the leather side of the laminate. The laminate was then left overnight to allow the adhesive to fully dry.

[0184] The sample was then dry milled in a drum roller at in air at 40 C. at 80% relative humidity.

[0185] FIG. 1 shows the top grain leather prior to coating with the adhesive. FIG. 2a shows the leather side of the laminate prior to dry milling, with FIG. 3b showing the reverse side. Close inspection of FIGS. 1 and 2a show that there is some grain structure naturally present in the leather, but this is not present on the reverse side of the laminate prior to dry milling. Instead the reverse side of the laminate closely resembles the surface texture of the reinforcing fabric prior to lamination.

[0186] FIG. 3a shows the laminate following dry milling with the pronounced grain-like structure being developed. FIG. 3b shows the reverse side of the laminate, with the grain-like structure clearly evident in the reinforcing layer. FIG. 3c shows that the grain-like structure becomes much less pronounced when the laminate is bent.

EXAMPLE 2

[0187] Example 1 was repeated using a 1 mm thick nubuck leather sample. FIG. 4 shows the sample prior to lamination, with FIGS. 5a and 5b showing the front and back sides of the laminate prior to dry milling. As with Example 1, a very fine pebbled structure is evident in the nubuck leather sample, but this is not evident on the reverse side of the laminate prior to dry milling. Instead, the surface texture closely resembles that of the reinforcing layer prior to lamination.

[0188] FIG. 6a shows the laminate after dry milling, with the pronounced shrunken pebbled texture clearly evident. FIG. 6b shows the reverse side of this laminate, with the grain like structure present on the reinforcing layer. FIG. 6c shows that the grain-like structure is significantly reduced when the laminate is bent.

[0189] FIG. 7 shows the same dry milled laminate with a finger trail on the surface. The finger trail was formed by first brushing the entire surface in a first direction (in this case towards the ruler), then dragging a fingertip in the opposite direction (in this case away from the ruler). The figure shows the fingertip leaving a trail meaning that the nubuck leather has developed the grain-like structure through dry milling while retaining its velvet-like surface.

EXAMPLE 3

[0190] Three 30 cm by 30 cm samples of top grain leather were subjected to the following processes: [0191] Sample 3-1 was dry milled at 40 C. and 80% humidity for 3 hours [0192] Sample 3-2 was laminated to a fabric containing Dyneema fibres, then dry milled at 40 C. and 80% humidity for 3 hours under identical conditions to Sample 3-1. [0193] Sample 3-3 was laminated to a fabric containing Dyneema fibres, soaked in water then dry milled at 40 C. with the drum being intermittently purged to reduce the humidity to ambient levels.

[0194] FIG. 8 shows the three samples after these processes laid out with their left edges lined up, stacked (in order) as 3-1, 3-2 and 3-3.

[0195] Although it has undergone a slight shrinkage (around 2%), the non-laminated sample shows very little surface texture and is almost indistinguishable from the non-milled leather.

[0196] Sample 3-2 shows a very even pebbled surface texture across its entire surface. It has shrunk in size by around 5.3% following the milling in humid air.

[0197] Sample 3.3 shows a more weathered texture with more pronounced pebbling and a larger colour difference between the grain peaks and grain valleys. It has also contracted more, reducing in size by about 7.7%.