Multi-layer laminates with film embossed on one side, base on partially acetalized polyvinyl alcohol

Abstract

The invention relates to an embossing process for the production of a film based on partially acetalized polyvinyl alcohol. The film is embossed on one side with a roughnesses, Rz, of 20 to 80 sum by embossing the side of the film between correspondingly roughened embossing rollers and pressing rollers with a certain Shore A hardness. The temperature of the film and the rollers is adjusted in order to fix the structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawing wherein:

FIG. 1 illustrates the surface of the embossing zone between the embossing roller and the pressing roller;

FIG. 2 illustrates an embodiment according to the invention; and

FIG. 3 illustrates another embodiment according to the invention.

Claims

1. A process for the production of a film based on partially acetalized polyvinyl alcohol, said process comprising: a. providing a film based on partially acetalized polyvinyl alcohol, wherein a first side of said file has a roughness, Rz, of 1 to 30 μm and a second side of said file has a roughness, Rz, of 1 to 30 μm, andb. embossing said second side of the film between a correspondingly roughened embossing roller at a temperature of 80 to 170° C. and a pressing roller at a temperature of 0 to 60° C. to obtain a film with an embossed surface with a roughness, Rz, of 20 to 100 μm,

2. A process according to claim 1, wherein film is exposed to a line pressure of 20 to 80 N/mm between said embossing roller and said pressing roller.

3. A process according to claim 1, wherein said pressing roller has a rubber or EPDM surface.

4. A process according to claim 1, wherein the temperature difference of the embossing roller is less than 2° C. across the width and the circumference of the roller.

5. A process according to claim 1, wherein the temperature difference of the pressing roller is less than 2° C. across the width and circumference of the roller.

6. A process according to claim 1, wherein the surface of the embossed side of the film has a roughness Rz of 20 to 80 μm.

7. A process according to claim 1, wherein the temperature of the film is adjusted to −10 0 to +20° C. before and/or after process step b).

8. A process according to claim 1, wherein the embossed side of the film is cooled.

9. A process according to claim 1, wherein the non-embossed side of the film is cooled.

10. A process according to claim 1, wherein the surface of the embossed side of the film has a roughness Rz of 30 to 50 μm.

11. A process according to claim 1, wherein each of the surfaces of the film provided in a) has a roughness, Rz, of 1 to 20 μm.

12. A process according to claim 1, wherein each of the surfaces of the film provided in a) has a roughness, Rz, of 1 to 10 μm.

13. A process according to claim 1, wherein the temperature of said embossing roller is 80 to 170°C.

14. A process according to claim 1, wherein the temperature of said embossing roller is 100 to 150° C.

15. A process according to claim 1, wherein the temperature of said embossing roller is 110 to 140° C.

16. A process according to claim 1, wherein said film is exposed to a line pressure of 40 to 65 N/mm between said embossing roller and said pressing roller.

17. A process according to claim 1, wherein the temperature of said pressing roller is 10 to 40° C.

18. A process according to claim 1, wherein said pressing roller has a Shore A hardness of 60 to 75.

19. A process according to claim 1, wherein said film contains at least one reducing adhesion substance to reduce the adhesion of the film to the embossing rollers.

20. A process according to claim 19, wherein said at least one reducing adhesion substance is a pentaerythritol compound according to formula I:

20. A process according to claim 1, wherein said film based on partially acetalized polyvinyl alcohol is a film based on partially acetalized polyvinyl butyral.

21. A laminate comprising: one or more polymer films and at least two embossed films produced according to the process of claim 1, said one or more polymer films being arranged between the non-embossed sides of said at least two embossed films.