Polarizing film, optical film and liquid crystal display using polarizing film

• US 6,961,178 B2
• Filed: 04/04/2002
• Issued: 11/01/2005
• Est. Priority Date: 04/06/2001
• Status: Expired due to Fees

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Tsuchimoto, Kazuki, Sugino, Youichirou, Shouda, Takashi
• Primary Examiner(s): Boutsikaris, Leonidas
• Application Number:
  US10/117,843
• Publication Number:
  US 20030189754A1
• Time in Patent Office: 1,307 Days
• Field of Search: 359/483, 359/485, 359/492, 359/494, 359/500, 156/499, 156/213, 156/304.4, 156/99, 100/90, 100/211, 428/216, 264/1.34, 344/96
• US Class Current: 359/485.03
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/08 using ultrasonic vibrations non-plastics element to plastics elements B29C65/645
• CPC Class Codes: B29C 65/10 using hot gases (e.g. combustion gases) or flames coming in contact with at least one of the parts to be joined
• CPC Class Codes: B29C 65/1412 Infrared [IR] radiation
• CPC Class Codes: B29C 65/18 using heated tools
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/45 Joining of substantially the whole surface of the articles methods or apparatus for laminating B32B37/00
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/712 the composition of one of the parts to be joined being different from the composition of the other part
• CPC Class Codes: B29C 66/723 being multi-layered B29C66/7292, B29C66/72941 take precedence
• CPC Class Codes: B29C 66/72321 consisting of metals or their alloys
• CPC Class Codes: B29C 66/72343 for liquids
• CPC Class Codes: B29C 66/73116 of different melting point, i.e. the melting point of one of the parts to be joined being different from the melting point of the other part
• CPC Class Codes: B29C 66/73365 at least one of the parts to be joined being transparent or translucent to visible light
• CPC Class Codes: B29C 66/7338 at least one of the parts to be joined being polarising
• CPC Class Codes: B29C 66/83413 cooperating rollers, cylinders or drums
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/919 characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/91921 in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/003 : PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29K 2995/0034 : Polarising
• CPC Class Codes: B29L 2009/00 : Layered products
• CPC Class Codes: B32B 17/10018 : comprising only one glass sheet
• CPC Class Codes: B32B 2037/0092 : in which absence of adhesives is explicitly presented as an advantage
• CPC Class Codes: B32B 2307/42 : Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2457/20 : Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 27/30 : comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/36 : comprising polyesters
• CPC Class Codes: B32B 37/04 : characterised by the partial melting of at least one layer
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C03C 17/3405 : with at least two coatings of organic materials C03C17/36, C03C17/42 take precedence
• CPC Class Codes: C03C 2218/365 : Coating different sides of a glass substrate
• CPC Class Codes: G02B 5/3033 : in the form of a thin sheet or foil, e.g. Polaroid

Abstract

A polarizing film comprising a polarizer (A) and a protection film (B) prepared on at least one face of the polarizer (A), wherein the protection film (B) is adhered to the polarizer (A) without using adhesives, is induced problems by use of adhesives.

Claims

1. A polarizing film comprising a polarizer (A) and a protection film (B) prepared on at least one face of the polarizer (A), wherein the protection film (B) is adhered to the polarizer (A) without using adhesives, wherein the protection film (B) is formed by at least two layers of the same materials but having different softening points, the layer having the lower softening point being located on a side of the protection film (B) facing the polarizer (A), and wherein the polarizer (A) is a dyed and stretched hydrophilic polymer film.

2. The polarizing film according to claim 1, wherein an adhesive strength between the polarizer (A) and the protection film (B) is not less than 10N/25 mm.

3. The polarizing film according to claim 1, wherein a retardation within a plane of the protection film (B) is not more than 10 nm.

4. The polarizing film according to claim 1, wherein a thickness of the protection film (B) is not more than 50 micrometers.

5. The polarizing film according to claim 1, wherein a moisture permeability of the protection film (B) is not more than 60 g/m²-24 hours-atm.

6. The polarizing film according to claim 1, wherein an elastic modulus of the protection film (B) is not less than 2000 N/mm².

7. The polarizing film according to claim 1, wherein a surface free energy on a side of the protection film (B) to which the polarizer (A) is not adhered is not less than 40 mN/m.

8. The polarizing film according to claim 1, wherein a light transmittance of a protection film (B) is not less than 86%.

9. The polarizing film according to claim 1, wherein light transmittance is not less than 42%, and polarization degree is not less than 95%.

10. An optical film, wherein at least one sheet of the polarizing film according to claim 1 is laminated.

11. A visual display comprising the polarizing film according to claim 1.

12. The polarizing film according to claim 6, wherein the elastic modulus of the protection film (B) is not less than 2500 N/mm².

13. The polarizing film according to claim 2, wherein the adhesive strength between the polarizer (A) and the protection film (B) is not less than 12N/25 mm.

14. The polarizing film according to claim 2, wherein the adhesive strength between the polarizer (A) and the protection film (B) is not less than 14N/25 mm.

15. The polarizing film according to claim 7, wherein the surface free energy on a side of the protection film (B) to which the polarizer (A) is not adhered is not less than 50 mN/m.

16. The polarizing film according to claim 7, wherein the surface free energy on a side of the protection film (B) to which the polarizer (A) is not adhered is not less than 56 mN/m.

17. The polarizing film according to claim 8, wherein a light transmittance of a protection film (B) is not less than 88%.

18. The polarizing film according to claim 8, wherein a light transmittance of a protection film (B) is not less than 92.4%.

19. The polarizing film according to claim 9, wherein the light transmittance is not less than 42.5%, and the polarization degree is not less than 98%.

20. The polarizing film according to claim 9, wherein the light transmittance is not less than 43.6%, and the polarization degree is not less than 99.9%.

21. The polarizing film according to claim 1, wherein a difference between the softening points is not less than 5°

C.

22. The polarizing film according to claim 21, wherein a difference between the softening points is not less than 10°

C.

23. The polarizing film according to claim 1, wherein the layer with a lower softening point on a side to which a polarizer (A) is adhered has a thickness of about 1 to about 100 micrometers.

24. The polarizing film according to any one of claims 1 and 2, wherein the protection film (B) has a thickness of not more than 500 micrometers.

25. The polarizing film according to any one of claims 1 and 2, wherein the protection film (B) has a thickness of 1 to 300 micrometers.

26. The polarizing film according to any one of claims 1 and 2, wherein the protection film (B) has a thickness of 5 to 200 micrometers.

27. The polarizing film according to any one of claims 1 and 2, wherein the protection film (B) has a thickness of from 1 to 300 micrometers.

28. The polarizing film according to any one of claims 1 and 2, wherein the protection film (B) has a thickness of from 5 to 200 micrometers.