# US 7,611,760 B2 · Cellulose acylate film, optical compensation film, polarizing plate and liquid crystal display

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- Number: US 7,611,760 B2
- Document ID: US7611760B2
- Status: Granted
- Kind: B2
- Application number: 11/408,029
- Filed: 2006-04-21
- Published: 2006-11-16
- Granted: 2009-11-03
- Earliest claimed: 2005-04-22
- Assignees: FUJIFILM Corporation
- Inventors: Hidenori Hayashi; Keiichi Taguchi; Kunihiro Atsumi; Yutaka Nozoe
- Web page: https://patentgrep.com/patent/US7611760B2

## CPC

- C08B 3/06: Cellulose acetate {, e.g. mono-acetate, di-acetate or tri-acetate}
- C08B 3/16: Preparation of mixed organic cellulose esters {, e.g. cellulose aceto-formate or cellulose aceto-propionate}
- C08B 3/18: Aceto-butyrates
- C08J 5/18: Manufacture of films or sheets
- C09K 19/02: characterised by optical, electrical or physical properties of the components, in general
- C08J 2301/12: Cellulose acetate
- C09K 2323/02: Alignment layer characterised by chemical composition
- C09K 2323/035: Ester polymer, e.g. polycarbonate, polyacrylate or polyester
- G02B 1/11: Anti-reflection coatings
- G02B 1/14: Protective coatings, e.g. hard coatings
- G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid}
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A cellulose acylate film is provided and has an elasticity modulus of 4,800 MPa to 10,000 MPa in at least either a machine direction MD at film-formation time or a direction TD perpendicular to the machine direction.

## Claims

### Claim 1

A cellulose acylate film having an elasticity modulus of 4,800 MPa to 10,000 MPa in at least one direction of a machine direction MD in producing of the cellulose acylate film and a transverse direction TD perpendicular to the machine direction, the cellulose acylate film having an in-plane retardation Re(λ) satisfying Expression: 20 nm ≦Re(590)≦200 nm and a thickness-direction retardation Rth(λ) satisfying Expression: 70 nm≦Rth(590)≦350 nm, and the cellulose acylate film having a thickness of 40 μm to 150 μm;
wherein the cellulose acylate film comprises mixed fatty acid ester of cellulose, wherein a hydroxyl group of the cellulose is substituted by an acetyl group, another hydroxyl group of the cellulose is substituted by an acyl group having 3 or more carbon atoms, and the cellulose acylate film satisfies Expressions (I) and (II):
2.0≦A+B≦3.0 (I)
0<B (II)
wherein A represents a substitution degree of the acetyl group, and B represents a substitution degree of the acyl group having 3 or more carbon atoms; and wherein the mixed fatty acid ester of cellulose is a cellulose acylate comprising a glucose unit, wherein a hydroxyl group of the glucose unit is substituted by the acetyl group or the acyl group having 3 or more carbon atoms, and the cellulose acylate film satisfies Expressions (III) and (IV):
2.0≦DS2≦DS3≦DS6≦2.85 (III)
DS6/(DS2+DS3DS6)≧0.315 (IV)
wherein DS2 represents a substitution degree of the acyl group for a 2-position hydroxyl group of the glucose unit, DS3 a substitution degree of the acyl group for a 3- position hydroxyl group of the glucose unit, and DS6 a substitution degree of the acyl group for a 6-position hydroxyl group of the glucose unit.

### Claim 2 (depends on 1)

The cellulose acylate film according to claim 1, which is produced by stretching a film having a solvent in a proportion of 20% by weight or less at the start of the stretching.

### Claim 3 (depends on 1)

The cellulose acylate film according to claim 1, which has undergone a stretching at a drawing ratio of 1.01 to 3.

### Claim 4 (depends on 1)

The cellulose acylate film according to claim 1, which has undergone a stretching at a temperature of 70° C. to 250° C.

### Claim 5 (depends on 1)

The cellulose acylate film according to claim 1, wherein the acyl group is a butanoyl group.

### Claim 6 (depends on 1)

The cellulose acylate film according to claim 1, wherein the acyl group is a propionyl group, and the substitution degree B is at least 0.6.

### Claim 7 (depends on 1)

The cellulose acylate film according to claim 1, which comprises a retardation developer.

### Claim 8 (depends on 1)

The cellulose acylate film according to claim 1, which comprises a retardation developer in an amount of 10 parts by weight or less with respect to 100 parts by weight of cellulose acylate.

### Claim 9 (depends on 1)

The cellulose acylate film according to claim 1, which comprises at least one of a plasticizer, an ultraviolet absorber and a release accelerator.

### Claim 10 (depends on 1)

A polarizing plate comprising: a polarizer; a protective film of a cellulose acylate film according to claim 1, and at least one layer of hard coating layer, an antiglare layer and an antireflection layer, in this order, wherein the polarizer is disposed between the protective film and a liquid crystal cell.

### Claim 11 (depends on 1)

A liquid crystal display device comprising a cellulose acylate film according to claim 1.

### Claim 12 (depends on 11)

The liquid crystal display according to claim 11, which is of VA mode.