One-sided-protected polarizing film, pressure-sensitive-adhesive-layer-attached polarizing film, image display device, and method for continuously producing same

• US 10,061,066 B2
• Filed: 09/29/2015
• Issued: 08/28/2018
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Ueno, Tomonori, Mita, Satoshi, Motegi, Yusuke, Xu, Jingfan, Kishi, Atsushi, Miyatake, Minoru
• Primary Examiner(s): Khatri, Prashant J
• Application Number:
  US15/515,887
• Publication Number:
  US 20170299790A1
• Time in Patent Office: 1,064 Days
• CPC Class Codes: B32B 2038/045 Slitting
• CPC Class Codes: B32B 2307/308 Heat stability dimensional stability B32B2307/734
• 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 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 37/02 characterised by a sequence of laminating steps, e.g. by adding new layers at consecutive laminating stations
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: B32B 37/182 one or more of the layers being plastic
• CPC Class Codes: B32B 38/10 Removing layers, or parts of layers, mechanically or chemically
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers

Abstract

The present invention pertains to a one-side-protected polarizing film having a transparent protective film on only one surface of a polarizer, wherein: the polarizer contains a polyvinyl alcohol-based resin, has a thickness of 10 μm or less, and is designed to have a single-body transmittance T and a polarization degree P representing optical properties satisfying the condition of the following formula: P>−(10^{0.929T−42.4}−1)×100 (provided that T<42.3) or P≥99.9 (provided that T≥42.3); and the other surface of the polarizer has a transparent resin layer having a thickness of 0.2 μm or more and formed from a layer-forming material including a polyvinyl alcohol-based resin. Even when the polarizer has prescribed optical properties and the thickness is 10 μm or less, this one-side-protected polarizing film is capable of suppressing the occurrence of through cracks and nano-slits.

Claims

1. A one-side-protected polarizing film, comprising:

a polarizer;

a transparent protective film provided on only one surface of the polarizer; and

a transparent resin layer provided on another surface of the polarizer, wherein

the polarizer comprises a polyvinyl alcohol-based resin, has a thickness of 10 μ

m or less, and is designed to have a single-body transmittance T and a polarization degree P representing optical properties satisfying the condition of the following formula;

P>

−

(10<sup>0.929T−

42.4</sup>−

1)×

100 (provided that T<

42.3) or P≥

99.9 (provided that T≥

42.3), and

the transparent resin layer has a thickness of 0.2 μ

m or more and is a product made from a layer-forming material comprising a polyvinyl alcohol-based resin and is an unstretched layer.

2. The one-side-protected polarizing film according to claim 1, wherein the transparent resin layer has a heat of crystal fusion of 30 mJ/mg or more.

3. The one-side-protected polarizing film according to claim 1, wherein the transparent resin layer has the thickness of less than 3 μ

m.

4. The one-side-protected polarizing film according to claim 1, wherein the polyvinyl alcohol-based resin for forming the transparent resin layer has a saponification degree of 99.0% or more and an average degree of polymerization of 1,000 or more.

5. The one-side-protected polarizing film according to claim 1, wherein the layer-forming material is free of any curable component.

6. The one-side-protected polarizing film according to claim 1, wherein the polyvinyl alcohol-based resin for forming the transparent resin layer is a polyvinyl alcohol resin.

7. The one-side-protected polarizing film according to claim 1, wherein the polarizer contains 25% by weight or less of boric acid based on the total weight of the polarizer.

8. A pressure-sensitive-adhesive-layer-attached polarizing film comprising:

the one-side-protected polarizing film according to claim 1; and

a pressure-sensitive adhesive layer.

9. The pressure-sensitive-adhesive-layer-attached polarizing film according to claim 8, wherein the pressure-sensitive adhesive layer is provided on the transparent resin layer of the one-side-protected polarizing film.

10. The pressure-sensitive-adhesive-layer-attached polarizing film according to claim 8, wherein the pressure-sensitive adhesive layer is provided on the transparent protective film of the one-side-protected polarizing film.

11. The pressure-sensitive-adhesive-layer-attached polarizing film according to claim 8, further comprising a separator provided on the pressure-sensitive adhesive layer.

12. The pressure-sensitive-adhesive-layer-attached polarizing film according to claim 11, which is in the form of a roll.

13. An image display device comprising the one-side-protected polarizing film according to claim 1.

14. An image display device comprising the pressure-sensitive-adhesive-layer-attached polarizing film according to claim 8.

15. A method for producing the one-side-protected polarizing film according to claim 1, comprising:

the polarizer;

the transparent protective film provided on only one surface of the polarizer; and

the transparent resin layer provided on another surface of the polarizer, wherein

the polarizer comprises a polyvinyl alcohol-based resin, has a thickness of 10 μ

m or less, and is designed to have a single-body transmittance T and a polarization degree P representing optical properties satisfying the condition of the following formula;

P>

-(10<sup>0.929T−

42.4</sup>−

1)×

100 (provided that T<

42.3) or P≥

99.9 (provided that T≥

42.3),

the transparent resin layer has a thickness of 0.2 μ

m or more and is a product made from a layer-forming material comprising a polyvinyl alcohol-based resin, and

the transparent resin layer is provided by applying the layer-forming material comprising the polyvinyl alcohol-based resin on another surface of the polarizer.

16. A method for continuously producing an image display device, the method comprising the steps of:

unwinding the pressure-sensitive-adhesive-layer-attached polarizing film from the roll of the pressure-sensitive-adhesive-layer-attached polarizing film according to claim 12;

feeding the pressure-sensitive-adhesive-layer-attached polarizing film with the separator; and

continuously bonding the pressure-sensitive-adhesive-layer-attached polarizing film to a surface of an image display panel with the pressure-sensitive adhesive layer interposed therebetween.