Retardation film, circularly-polarizing plate, and image-displaying device

Patent metadata

Field	Value
Publication number	US-10754065-B2
Application number	US-201615294055-A
Country	US
Kind code	B2
Filing date	Oct 14, 2016
Priority date	Apr 16, 2014
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

An object of the present invention is to provide a retardation film excellent in various properties such as optical properties, heat resistance, mechanical properties, and reliability. The present invention relates to a retardation film containing a thermoplastic resin and composed of a single layer, in which the retardation film has a value of wavelength dispersion that is a ratio of retardations at a wavelength of 450 nm and at a wavelength of 550 nm being 0.75 or more and 0.92 or less; a birefringence at a wavelength of 550 nm and the wavelength dispersion satisfy a relationship of Δn≥0.0140×(R450/R550)−0.0082; and a photoelastic coefficient is 25×10 −12 Pa −1 or less.

First claim

The invention claimed is:

1. A circularly polarizing plate comprising a retardation film and a polarizer stacked on the retardation film,
the retardation film comprising a thermoplastic resin and composed of a single layer,
wherein the retardation film has:
a value of wavelength dispersion (R450/R550) as a ratio of an in-plane retardation (R450) at a wavelength of 450 nm and an in-plane retardation (R550) at a wavelength of 550 inn being 0.75 or more and 0.92 or less;
a birefringence (Δn) at a wavelength of 550 nm satisfying a relationship of the following mathematical formula (I) with the wavelength dispersion (R450/R550); and
a photoelastic coefficient of 25×10 −12 Pa −1 or less:
birefringence= R 550[nm]/(film thickness[mm]×10 6 ),

Δ n≥ 0.0140×( R 450 /R 550)−0.0082  (I),

wherein the thermoplastic resin comprises at least one bonding group of a carbonate bond and an ester bond and one or more structural units selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2),
wherein in the thermoplastic resin, a content of an aromatic group-containing structural unit other than the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) is 5% by mass or less:

wherein in the general formula (1) and the general formula (2), each of R 1 to R 3 is independently a direct bond or an alkylene group having a carbon number of from 1 to 4, which may have a substituent, and each of R 4 to R 9 is independently hydrogen atom, an alkyl group having a carbon number of from 1 to 10, which may have a substituent, an aryl group having a carbon number of from 4 to 10, which may have a substituent, an acyl group having a carbon number of from 1 to 10, which may have a substituent, an alkoxy group having a carbon number of from 1 to 10, which may have a substituent, an aryloxy group having a carbon number of from 1 to 10, which may have a substituent, an acyloxy group having a carbon number of from 1 to 10, which may have a substituent, an amino group which may have a substituent, a vinyl group having a carbon number of from 1 to 10, which may have a substituent, an ethynyl group having a carbon number of from 1 to 10, which may have a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group, provided that at least two adjacent groups out of R 4 to R 9 may be linked to each other to form a ring.

2. The circularly polarizing plate according to claim 1 , wherein the thermoplastic resin has a refractive index at a sodium d line (589 mm) of from 1.49 to 1.56.

3. The circularly polarizing plate according to claim 1 , wherein the thermoplastic resin has a glass transition temperature of 120° C. to 160° C.

4. The circularly polarizing plate according to claim 1 , wherein the thermoplastic resin has an elastic modulus of 1 GPa to 2.5 GPa.

5. The circularly polarizing plate according to claim 1 , wherein the thermoplastic resin comprises the structural unit represented by the general formula (1) or the general formula (2) in an amount of 1% to 40% by mass in total.

6. The circularly polarizing plate according to claim 1 , wherein the thermoplastic resin comprises a structural unit represented by the following general formula (3)

7. An image display device comprising the circularly polarizing plate according to claim 1 .

8. An organic EL panel comprising the circularly polarizing plate according to claim 1 .

Assignees

• Nitto Denko Corp
• Mitsubishi Chem Corp

Inventors

• Namiki Shingo
• Hirami Yuuichi
• Uehara Hisatoshi
• Hayashi Hiroyuki
• Shimizu Takashi
• Sumimura Hiroshi
• Murakami Nao

Classifications

• G02B1/08 Primary

  made of polarising materials · CPC title

• H10K59/8791

  Arrangements for improving contrast, e.g. preventing reflection of ambient light · CPC title

• H10K59/879

  comprising refractive means, e.g. lenses · CPC title

• G02B5/3083 Primary

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• H10K50/868

  Arrangements for polarized light emission (H10K50/86 takes precedence) · CPC title