Method of making a polarizing sheet and method of lamination

• US 20080224340A1
• Filed: 05/21/2007
• Published: 09/18/2008
• Est. Priority Date: 03/14/2007
• Status: Abandoned Application

• Current Assignee: Daxon Technology Incorporated
• Original Assignee: Daxon Technology Incorporated
• Inventors: Tsai, Cheng-Hsin
• Application Number:
  US11/751,048
• Publication Number:
  US 20080224340A1
• Time in Patent Office: Days
• US Class Current: 264/1.34
• CPC Class Codes: B29C 55/06 parallel with the direction of feed
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29K 2995/0034 Polarising

Abstract

A method of making a polarizing sheet and a related method of lamination are disclosed. The method of making a polarizing sheet includes steps of forming a surface-modified polarizer having carboxylic groups from a polyvinyl alcohol (PVA) film, and then performing a thermocompression lamination to laminate the polarizer with at least one protective film having hydroxyl groups on a surface thereof to form a polarizing sheet.

Claims

1. A method of making a polarizing sheet, comprising steps of:

forming a polarizer from a polyvinyl alcohol (PVA) film, wherein the polarizer is surface-modified to carry carboxylic groups; and

performing a thermocompression lamination to laminate the polarizer with at least a protective film having hydroxyl groups on a surface thereof.

2. The method according to claim 1, wherein the polarizer is surface-modified by carrying out a reaction between a carboxylic acid containing at least two carboxylic groups or a derivative thereof and the hydroxyl groups of the PVA film in a presence of a catalyst to form ester bonds, such that the surface of the resulting polarizer carries carboxylic groups.

3. The method according to claim 2, wherein the carboxylic acid comprises ethanedioic acid, propanedioic acid, butanedioic acid, glutaric acid, adipic acid, or pimelic acid.

4. The method according to claim 2, wherein the catalyst comprises a Lewis acid.

5. The method according to claim 4, wherein the Lewis acid comprises an aluminum ion, a zinc ion, a metal salt having an aluminum ion or a zinc ion, or a metal complex having an aluminum ion or a zinc ion.

6. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water;

surface-modifying the swelled PVA film to allow the surface of the swelled PVA film to carry carboxylic groups;

dip-dyeing the surface-modified PVA film in a dye solution;

stretching the dip-dyed PVA film in a boric acid solution; and

drying the stretched PVA film to form the polarizer.

7. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water and simultaneously surface-modifying the PVA film to allow the surface of the PVA film to carry carboxylic groups;

dip-dyeing the swelled and surface-modified PVA film in a dye solution;

stretching the dip-dyed PVA film in a boric acid solution; and

drying the stretched PVA film to form the polarizer.

8. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water;

dip-dyeing the swelled PVA film in a dye solution;

surface-modifying the dip-dyed PVA film to allow the surface of the dip-dyed PVA film to carry carboxylic groups;

stretching the surface-modified PVA film in a boric acid solution; and

drying the stretched PVA film to form the polarizer.

9. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water;

dip-dyeing the swelled PVA film in a dye solution and simultaneously surface-modifying the swelled PVA film to allow the surface of the swelled PVA film to carry carboxylic groups;

stretching the dip-dyed and surface-modified PVA film in a boric acid solution; and

drying the stretched PVA film to form the polarizer.

10. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water;

dip-dyeing the swelled PVA film in a dye solution;

stretching the dip-dyed PVA film in a boric acid solution and simultaneously surface-modifying the dip-dyed PVA film to allow the surface of the dip-dyed PVA film to carry carboxylic groups; and

drying the stretched and surface-modified PVA film to form the polarizer.

11. The method according to claim 1, wherein forming the polarizer from the polyvinyl alcohol (PVA) film comprises steps of:

swelling the PVA film in water;

dip-dyeing the swelled PVA film in a dye solution;

stretching the dip-dyed PVA film in a boric acid solution;

surface-modifying the stretched PVA film to allow the surface of the stretched PVA film to carry carboxylic groups; and

drying the surface-modified PVA film to form the polarizer.

12. The method according to claim 1, wherein the protective film comprises an alkaline solution-dipped cellulose film, a derivative of an alkaline solution-dipped cellulose film, a polyvinyl ester hydrolysate, partially dehydrated PVA film, a plasma- or corona-treated film, a film coated with a polymer having hydroxyl groups, or a film coated with a resin having hydroxyl groups.

13. The method according to claim 12, wherein the cellulose film comprises a triacetyl cellulose (TAC) film or a diacetyl cellulose (DAC) film.

14. The method according to claim 12, wherein the plasma- or corona-treated film comprises cyclic olefin polymer (COP), polycarbonate (PC), or cyclic olefin copolymer (COC).

15. The method according to claim 1, before performing a thermocompression lamination, further comprising a step of adding a wetting liquid between the polarizer and the protective film.

16. The method according to claim 15, wherein the wetting liquid comprises water, or an organic solvent having a low boiling point.

17. The method according to claim 15, wherein the wetting liquid comprises a catalyst for catalyzing a reaction between a hydroxyl group and a carboxylic group to form an ester group.

18. The method according to claim 17, wherein the catalyst comprises a protic acid or a Lewis acid.

19. The method according to claim 1, before performing the thermocompression lamination, further comprising a step of preheating the protective film.

20. A method of lamination, comprising steps of:

providing a first film having carboxylic groups on a surface thereof;

providing a second film having hydroxyl groups on a surface thereof; and

performing a thermocompression lamination to laminate the first film with the second film.

21. The method according to claim 20, wherein the first film is subjected a surface modification to have the carboxylic groups on the surface thereof.

22. The method according to claim 21, wherein the first film originally had hydroxyl groups and the surface modification is performed using a carboxylic acid containing at least two carboxylic groups or a derivative thereof to react with the hydroxyl groups of the first film in a presence of a catalyst to form ester bonds, such that the surface of the first film carries carboxylic groups.

23. The method according to claim 22, wherein the carboxylic acid comprises ethanedioic acid, propanedioic acid, butanedioic acid, glutaric acid, adipic acid, or pimelic acid.

24. The method according to claim 22, wherein the catalyst comprises a Lewis acid.

25. The method according to claim 24, wherein the Lewis acid comprises an aluminum ion, a zinc ion, a metal salt having an aluminum ion or a zinc ion, or a metal complex having an aluminum ion or a zinc ion.

26. The method according to claim 20, wherein the first film comprises a polyvinyl alcohol film surface-modified to have carboxylic groups on the surface.

27. The method according to claim 20, wherein the second film comprises an alkaline solution-dipped cellulose film, a derivative of an alkaline solution-dipped cellulose film, a polyvinyl ester hydrolysate, partially dehydrated PVA film, a plasma- or corona-treated film, a film coated with a polymer having hydroxyl groups, or a film coated with a resin having hydroxyl groups.

28. The method according to claim 27, wherein the cellulose film comprises a triacetyl cellulose (TAC) film or a diacetyl cellulose (DAC) film.

29. The method according to claim 27, wherein the plasma- or corona-treated film comprises cyclic olefin polymer (COP), polycarbonate (PC), or cyclic olefin copolymer (COC).

30. The method according to claim 20, before performing a thermocompression lamination, further comprising a step of adding a wetting liquid between the first film and the second film.

31. The method according to claim 30, wherein the wetting liquid comprises water, or an organic solvent having a low boiling point.

32. The method according to claim 30, wherein the wetting liquid comprises a catalyst for catalyzing a reaction between a hydroxyl group and a carboxylic group to form an ester group.

33. The method according to claim 32, wherein the catalyst comprises a protic acid or a Lewis acid.

34. The method according to claim 20, before performing the thermocompression lamination, further comprising a step of preheating the second film.