Retardation film, and optical compensation layer, optical compensation polarizing plate, liquid crystal display device and organic EL display device each using said retardation film

Patent metadata

Field	Value
Publication number	US-9671544-B2
Application number	US-201415030683-A
Country	US
Kind code	B2
Filing date	Oct 20, 2014
Priority date	Oct 23, 2013
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

The present invention achieves a phase difference film that is excellent in wavelength dispersion property, in-plane retardation, and film thickness, by using a polymeric material (i) which is composed of at least one type of cellulose derivative having a specific alkoxyl group substitution degree D 1 and a specific 2-naphthoyl group substitution degree D 2 and (ii) which has a specific total 2-naphthoyl group substitution degree D 3 .

First claim

The invention claimed is:

1. A phase difference film, comprising:
a polymeric material comprising a cellulose derivative having a polymerization unit of the formula (1):

wherein each of R 1 , R 2 , and R 3 independently contains an aliphatic group, an unsaturated aliphatic group, or a 2-naphthoyl group,
wherein
the phase difference film has an in-plane retardation Re(550) of from 130 nm to 160 nm, a reverse wavelength dispersion property Re(450)/Re(550) of from 0.80 to 0.86, and a film thickness of from 20 μm to 50 μm,
in the cellulose derivative, a sum of substitution degrees D 1 of alkoxyl groups each containing an aliphatic group or an unsaturated aliphatic group is from 2.00 to 2.70,
in the cellulose derivative, a substitution degree D 2 of 2-naphthoyl groups is from 0.30 to 1.00,
in the polymeric material, a total substitution degree D 3 of 2-naphthoyl groups is from 0.41 to 0.50, and
the substitution degrees D 1 and D 2 satisfy D 1 +D 2 ≦3.0.

2. The phase difference film of claim 1 , wherein in the cellulose derivative, each of the alkoxyl groups in the formula (1) has an aliphatic alkyl group.

3. The phase difference film of claim 2 , wherein in the cellulose derivative, each of the alkoxyl groups in the formula (1) has an ethyl group.

4. A method for producing the phase difference film of claim 1 , comprising: stretching a base film including the polymeric material at a stretching ratio of from 20% to 200%, thereby forming the phase difference film.

5. The method of claim 4 , wherein the stretching comprises stretching the base film at a temperature in a range of from (Tg−10° C.) to (Tg+30° C.) with respect to a glass transition temperature Tg of the base film.

6. A circularly polarizing plate, comprising:
at least one phase difference film of claim 1 .

7. An image display device, comprising:
a circularly polarizing plate of claim 6 .

8. The phase difference film of claim 1 , wherein the cellulose derivative has a number average molar weight of from 10,000 to 300,000.

9. The phase difference film of claim 1 , wherein the polymeric material comprises a plurality of cellulose derivatives including the cellulose derivative having the polymerization unit of the formula (1).

10. The phase difference film of claim 1 , further comprising:
at least one additive selected from the group consisting of a plasticizer, a thermal stabilizer, and an ultraviolet light absorber.

11. The phase difference film of claim 1 , wherein the phase difference film has a film thickness of from 20 μm to 40 μm.

12. A phase difference film, comprising:
a polymeric material comprising a cellulose derivative having a polymerization unit of the formula (1):

wherein each of R 1 , R 2 , and R 3 independently contains an ethyl group or a 2-naphthoyl group,
wherein
the phase difference film has an in-plane retardation Re(550) of from 130 nm to 160 nm, a reverse wavelength dispersion property Re(450)/Re(550) of from 0.80 to 0.89, a film thickness of from 20 μm to 50 μm, and a haze of not more than 2.00%,
in the cellulose derivative, a sum of substitution degrees D 1 of ethyl groups is from 2.00 to 2.70,
in the cellulose derivative, a substitution degree D 2 of 2-naphthoyl groups is from 0.30 to 1.00,
in the polymeric material, a total substitution degree D 3 of 2-naphthoyl groups is from 0.40 to 0.50, and
the substitution degrees D 1 and D 2 satisfy D 1 +D 2 <3.0.

13. The phase difference film of claim 12 , wherein the phase difference film has a film thickness of from 20 μm to 40 μm.

14. A circularly polarizing plate, comprising:
at least one phase difference film of claim 12 .

15. An image display device, comprising:
a circularly polarizing plate of claim 14 .

16. A method for producing the phase difference film of claim 12 , the method comprising: stretching a base film including the polymeric material at a temperature of from 150° C. to 160° C., thereby forming the phase difference film.

17. The method of claim 16 , wherein the stretching comprises stretching the base film at a stretching ratio of from 20% to 60%.

18. The phase difference film of claim 12 , wherein the polymeric material comprises a plurality of cellulose derivatives including the cellulose derivative having the polymerization unit of the formula (1).

19. The phase difference film of claim 12 , further comprising:
at least one additive selected from the group consisting of a plasticizer, a thermal stabilizer, and an ultraviolet light absorber.

20. The phase difference film of claim 12 , wherein the cellulose derivative has a number average molar weight of from 10,000 to 300,000.

Assignees

• Kaneka Corp

Inventors

• Mukai Ryutaro
• Abo Tomohiro

Classifications

• C08J5/18

  Manufacture of films or sheets · CPC title

• G02F1/133528

  Polarisers · CPC title

• G02B5/305

  including organic materials, e.g. polymeric layers · CPC title

• G02F1/13363

  Birefringent elements, e.g. for optical compensation · CPC title

• B29C55/04

  uniaxial, e.g. oblique · CPC title