Polarizing plate laminated with an improved glue composition and a method of manufacturing the same

• US 20050249932A1
• Filed: 01/03/2005
• Published: 11/10/2005
• Est. Priority Date: 05/04/2004
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Wang, Yongcai, McCovick, Robert E., Linehan, Daniel T.
• Granted Patent: US 7,399,376 B2
• Time in Patent Office: Days
• US Class Current: 428/219
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B32B 2037/243 Coating
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2329/04 Polyvinylalcohol
• CPC Class Codes: B32B 2331/04 Polymers of vinyl acetate, e.g. PVA
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/26 using curing agents
• CPC Class Codes: B32B 27/30 comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 37/206 Laminating a continuous layer between two continuous plastic layers
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 1/16 having an anti-static effect, e.g. electrically conducting coatings
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

The present invention generally relates a method of forming a polarizing plate comprising providing two protective cover sheets, each protective cover sheet for polarizers comprising a low birefringence protective polymer film and a layer promoting adhesion to poly(vinyl alcohol)-containing films comprising a hydrophilic polymer. The cover sheets are brought into contact with a PVA dichroic polarizing film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dichroic polarizing film. A glue composition is applied just before contacting said PVA dichroic polarizing film and said cover sheets, said glue composition being substantially free of dissolved polymer and comprising a crosslinking agent that crosslinks PVA.

Claims

1. A polarizing plate comprising a protective cover sheet for polarizers comprising a low birefringence protective polymer film, a layer promoting adhesion to poly(vinyl alcohol)-containing films and comprising a hydrophilic polymer, wherein the layer promoting adhesion to poly(vinyl alcohol)-containing films has been adhesively attached to a PVA dichroic polarizing film by a glue composition that is substantially free of dissolved polymer and that comprises a crosslinking agent for poly(vinyl alcohol).

2. The protective cover sheet of claim 1 wherein said layer promoting adhesion has a dry weight of between 5 and 300 mg/ft² (50 to 3000 mg/m²).

3. The protective cover sheet of claim 1 wherein said layer promoting adhesion has a water contact angle of less than 20°

.

4. The protective cover sheet of claim 1 wherein said layer promoting adhesion has water swell of between 10 and 1000 percent.

5. The protective cover sheet of claim 1 wherein said layer promoting adhesion further comprises a crosslinking compound.

6. The protective cover sheet of claim 1 wherein said layer promoting adhesion further comprises a multivalent ion.

7. The protective cover sheet of claim 1 wherein said low birefringence protective polymer film comprises cellulose ester.

8. The protective cover sheet of claim 1 wherein said low birefringence protective polymer film comprises a polycarbonate, poly(methyl methacrylate), or cyclic polyolefin.

9. The protective cover sheet of claim 1 wherein said glue composition is free of, or essentially free of, dissolved polymer and comprises a crosslinking agent that crosslinks PVA.

23. An electronic display device comprising said polarizing plate of claim 1.

10. A method of forming a polarizing plate comprising:

(a) providing two cover sheets, each cover sheet comprising a low birefringence protective polymer film and a layer promoting adhesion to poly(vinyl alcohol)-containing films that comprises a hydrophilic polymer;

(b) providing a PVA dichroic polarizing film; and

(c) simultaneously or sequentially bringing said two cover sheets into contact with said PVA dichroic polarizing film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dichroic polarizing film, wherein prior to contact a glue composition is applied to said PVA dichroic polarizing film or said two cover sheets, and wherein said glue composition is substantially free of dissolved polymer and comprises a crosslinking agent that crosslinks PVA.

11. The method of claim 10 wherein said glue composition is free of, or essentially free of, dissolved polymer and comprises a crosslinking agent that crosslinks PVA.

12. The method of claim 10 wherein said glue composition is applied to both sides of the PVA dichroic polarizing film or to a lowermost layer of said two cover sheets prior to said two cover sheets and said PVA dichroic polarizing film entering a nip between pinch rollers wherein said two cover sheets are laminated to either side of said PVA dichroic polarizing film, with application of pressure and optional heat, between opposing pinch rollers, resulting in said polarizer plate in sheet form.

13. The method of claim 10 wherein said glue composition comprises an inorganic crosslinking agent or an organic crosslinking agent or a combination of both.

14. The method of claim 10 wherein said crosslinking agent comprises a multivalent ion.

15. The method of claim 14 wherein said crosslinking agent comprises a coordination compound comprising titanium or zirconium.

16. The method of claim 14 wherein said crosslinking agent comprises boron.

17. The method of claim 10 wherein said crosslinking agent is an organic crosslinking agent selected from a group consisting of polycarboxylic acids and anhydrides, polyamines, epihalohydrins, diepoxides, dialdehydes, diols, carboxylic acid halides, and ketenes.

18. A method of forming a polarizing plate comprising:

(a) providing two guarded cover sheet composites each comprising a carrier substrate and a protective cover sheet that comprises a low birefringence protective polymer film and a layer promoting adhesion to poly(vinyl alcohol)-containing films that comprises a hydrophilic polymer;

(b) optionally removing said carrier substrates from said protective cover sheet to provide two unguarded cover sheets;

(c) providing a PVA dichroic film; and

(d) simultaneously or sequentially bringing said unguarded or guarded cover sheets into contact with said PVA dichroic film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dichroic film, wherein a glue composition is applied to said PVA dichroic film or said cover sheets before contact, and wherein said glue composition is substantially free of dissolved polymer and comprises a crosslinking agent that crosslinks poly(vinyl alcohol).

19. The method of claim 18 wherein said glue composition comprises an inorganic crosslinking agent or an organic crosslinking agent or a combination of both.

20. The method of claim 18 wherein said crosslinking agent comprises a multivalent ion.

21. The method of claim 20 wherein said crosslinking agent comprises boron.

22. The method of claim 18 wherein said crosslinking agent is an organic crosslinking agent selected from a group consisting of polycarboxylic acids and anhydrides, polyamines, epihalohydrins, diepoxides, dialdehydes, diols, carboxylic acid halides, and ketenes.