Optical film composite having spatially controlled adhesive strength

• US 20070134459A1
• Filed: 12/12/2005
• Published: 06/14/2007
• Est. Priority Date: 12/12/2005
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Wang, Yongcai, Lei, Herong, Anderson, Charles, Hubert, Timothy, Gros, Alain, Schultz, Ralph, Chen, Wen-Li
• Granted Patent: US 7,655,289 B2
• Time in Patent Office: Days
• US Class Current: 428/40.100
• CPC Class Codes: B32B 2037/243 Coating
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2310/14 Corona, ionisation, electrical discharge, plasma treatment
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 37/00 Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
• CPC Class Codes: B32B 38/0008 Electrical discharge treatment, e.g. corona, plasma treatment; wave energy or particle radiation heat treatment B32B38/0036
• CPC Class Codes: G02B 1/105 Protective coatings
• 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: Y02P 20/582 Recycling of unreacted starting or intermediate materials
• CPC Class Codes: Y10S 428/906 Roll or coil
• CPC Class Codes: Y10T 428/14 Layer or component removable to expose adhesive
• CPC Class Codes: Y10T 428/1481 Dissimilar adhesives
• CPC Class Codes: Y10T 428/24777 Edge feature
• CPC Class Codes: Y10T 428/24793 Comprising discontinuous or differential impregnation or bond
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

The present invention generally relates to optical films useful in the manufacture of polarizer plates, an improved method for producing polarizing plates, and a Liquid Crystal Display employing the same. More particularly, the invention relates to an optical film composite comprising a temporary carrier substrate having a center area and an edge area, said substrate having coated thereon an optical film wherein the adhesive strength between the optical film and the substrate is greater at the edge area than at the center area of the substrate.

Claims

1. An optical film composite comprising a temporary carrier substrate having a center area and an edge area, said substrate having coated thereon an optical film wherein the adhesive strength between the optical film and the substrate is greater at the edge area than at the center area of the substrate.

2. The optical film composite of claim 1 wherein the composite is in the form of a roll.

3. The optical film composite of claim 2 wherein the roll has a leading end area and a trailing end area and wherein the adhesive strength is also greater at the leading end area and the trailing end area than at the center area.

4. The optical film composite of claim 1 wherein the adhesive strength at the edge area is greater than the adhesive strength at the center area by a factor of at least 10.

5. The optical film composite of claim 1 wherein the adhesive strength at the edge area is greater than the adhesive strength at the center area by a factor of at least 50.

6. The optical film composite of claim 1 wherein the adhesive strength at the edge area is greater than the adhesive strength at the center area by a factor of at least 200.

7. The optical film composite of claim 1 wherein the varying adhesive strength is created by a surface energy treatment of the edge area of the substrate.

8. The optical film composite of claim 1 wherein the substrate comprises a release layer located adjacent to the optical film, said release layer covering substantially all of the center area of the substrate.

9. The optical film composite of claim 8 wherein the release layer comprises a silicone containing polymer.

10. The optical film composite of claim 1 wherein the optical film comprises a low birefringence polymer film.

11. The optical film composite of claim 1 wherein the optical film comprises a peelable layer located adjacent to the substrate, said peelable layer covering substantially all of the center area of the substrate.

12. The optical film composite of claim 11 wherein the peelable layer is an adhesive layer.

13. The optical film composite of claim 12 wherein the adhesive layer is polyvinyl alcohol.

14. The optical film composite of claim 1 wherein the optical film is a polarizer cover sheet.

15. The optical film composite of claim 1 wherein the optical film is triacetylcellulose, polycarbonate or a cyclic olefin polymer.

16. The optical film composite of claim 1 wherein the optical film further comprises a compensation layer or an abrasion resistant hard coat

17. The optical film composite of claim 1 wherein the substrate is polyethyleneterephthalate.

18. The optical film composite of claim 1 wherein substrate comprises a subbing layer on the edge areas adjacent to the optical film.

19. The optical film composite of claim 18 wherein the subbing layer comprises vinylidene chloride.

20. The optical film composite of claim 1 wherein the edge area comprises at least two percent of the substrate area.

21. The optical film composite of claim 1 wherein the leading end and the trailing end are individually at least 5 meters in length.

22. The optical film composite of claim 10 wherein the low birefringence polymer film is from 5 to 30 microns thick.

41. The optical film of claim 1 wherein the optical film is coated on both sides of the substrate.

23. A method of manufacturing an optical film composite comprising a temporary carrier substrate having a center area and an edge area, and an optical film comprising a low birefringence polymer film, wherein the adhesive strength between the optical film and the substrate will be greater at the edge areas than at the center area of the substrate, said method comprising providing a precursor substrate;

forming an edge area and a center area on the precursor substrate to provide a temporary carrier substrate wherein the center area has a different adhesive property than the edge area; and

coating and drying at least an optical film composition comprising a low birefringence polymer on the substrate to form the optical film.

24. The method of manufacturing of claim 23 wherein the edge area of the precursor substrate is subjected to a surface energy treatment.

25. The method of manufacturing of claim 24 wherein the surface energy treatment is a corona discharge treatment.

26. The method of manufacturing of claim 24 wherein a release layer is coated on the center area of the precursor substrate to form the temporary carrier substrate.

27. The method of manufacturing of claim 23 wherein a peelable layer is applied to the center area of the substrate prior to coating the low birefringence polymer composition.

28. The method of manufacturing of claim 23 wherein a subbing layer is applied to the edge area of the precursor carrier substrate to form the temporary carrier substrate.

29. The method of manufacturing of claim 23 wherein the optical film composite is manufactured in the form of a roll.

30. The method of manufacturing of claim 29 comprising forming a leading end area and a trailing end area on said roll wherein the adhesive strength is greater on the leading end area and the trailing end area than on the center area.

31. The method of manufacturing of claim 23 wherein adhesive strength in the edge area is greater than the adhesive strength in the center area by a factor of at least 10.

32. The method of manufacturing of claim 23 wherein adhesive strength in the edge area is greater than the adhesive strength in the center area by a factor of at least 50.

33. The method of manufacturing of claim 23 wherein adhesive strength in the edge area is greater than the adhesive strength in the center area by a factor of at least 200.

34. The method of manufacturing of claim 23 further comprising slitting the edge area off of the optical film composite.

35. The method of manufacturing of claim 28 wherein the peelable layer is coated simultaneously with low birefringence polymer composition.

37. The method of manufacturing of claim 23 wherein the optical film composition comprises knurls in the center area.

38. The method of manufacturing of claim 23 wherein the optical film is a polarizer cover sheet.

42. The method of manufacturing of claim 23 wherein said method comprising providing a precursor substrate;

forming an edge area and a center area on the precursor substrate on both side of the substrate to provide a temporary carrier substrate wherein the center area has a different adhesive property than the edge area; and

coating and drying at least a low birefringence polymer composition on both sides of the substrate to form the optical film.

39. A method of providing an optical film comprising taking an optical film composite comprising a temporary carrier substrate and an optical film having a center area and an edge area wherein the adhesive strength between the optical film and the substrate will be greater at the edge areas than at the center area of the substrate;

and removing the edge area.

40. The method of claim 39 wherein the optical film is a protective cover sheet for a polarizing plate, and further comprising the step of applying the protective cover sheet to the polarizing plate.