# US 9,040,129 B2 · Protective film of polarizer, polarizer and method for producing it, and liquid crystal display device

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- Number: US 9,040,129 B2
- Document ID: US9040129B2
- Status: Granted
- Kind: B2
- Application number: 13/064,927
- Filed: 2011-04-26
- Published: 2011-11-10
- Granted: 2015-05-26
- Earliest claimed: 2010-04-26
- Assignees: FUJIFILM Corporation
- Applicants: Nobutaka Fukagawa; Yu Naito; Masato Nagura; Yoshio Ishii
- Inventors: Nobutaka Fukagawa; Yu Naito; Masato Nagura; Yoshio Ishii
- Web page: https://patentgrep.com/patent/US9040129B2

## CPC

- C08L 1/12: Cellulose acetate
- C08J 5/18: Manufacture of films or sheets
- C08J 7/123: {Treatment by wave energy or particle radiation (C08J7/18 takes precedence)}
- C08K 5/092: Polycarboxylic acids
- C08K 5/10: Esters; Ether-esters
- C08K 5/175: {containing COOH-groups; Esters or salts thereof}
- C08K 5/46: with oxygen or nitrogen in the ring
- C08L 1/14: Mixed esters, e.g. cellulose acetate-butyrate
- C08L 67/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds (C08L67/06 takes precedence)
- B32B 2457/202: LCD, i.e. liquid crystal displays
- C08J 2301/12: Cellulose acetate
- C08J 2301/14: Mixed esters
- C09K 2323/03: Viewing layer characterised by chemical composition
- Y10T 428/31504: Composite [nonstructural laminate]
- Y10T 428/31971: Of carbohydrate
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- 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)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A protective film to a polarizer including a cellulose acylate and satisfying the following requirement (1) or (2): (1): The surface of the film has a pH of from 3.0 to 4.5. (2): The surface of the film has a pH of more than 4.5 and at most 6.0, and the film has a moisture permeability of at least 2800 g/m2·day.

## Claims

### Claim 1

A protective film to a polarizer containing a cellulose acylate and an organic acid having an octanol/water partition coefficient of at least 3.0 and satisfying one of the following requirements:
(1): The surface of the film has a pH of from 3.0 to 4.5; or
(2): The surface of the film has a pH of more than 4.5 and at most 6.0, and
wherein the film has a moisture permeability of at least 2800 g/m2 ·day,
the protective film to a polarizer comprising an organic acid represented by the following formula (1), wherein the ratio of the organic acid to the cellulose acylate is from 0.01 to 10% by mass:
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)−1
when L is a di- or more valent linking group.

### Claim 2 (depends on 1)

The protective film to a polarizer according to claim 1, of which the film surface pH is from 3.0 to 4.5.

### Claim 3 (depends on 1)

The protective film to a polarizer according to claim 1, wherein on condition that the surface of the film has a pH of from 3.0 to 4.5, the film has a moisture permeability of at least 2800 g/m2·day.

### Claim 4 (depends on 1)

The protective film to a polarizer according to claim 1, which has a water content of at least 4.0%.

### Claim 5 (depends on 1)

The protective film to a polarizer according to claim 1, wherein the organic acid represented by the formula (1) is a carboxylic acid derivative represented by the following formula (2):
wherein:
s and t each independently represent 1, 2 or 3;
R4 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an acyl group, an alkoxycarboxyl group, a carbamoyl group, an alkylsulfonyl group, an aryl sulfonyl group or a heterocyclic group, and each group may have a substituent, with the proviso that R4 includes the moiety of R1 in the formula (1).

### Claim 6 (depends on 1)

The protective film to a polarizer according to claim 1, wherein a total acyl substitution degree of the cellulose acyl ate is at least 1.0 and less than 2.6.

### Claim 7 (depends on 1)

The protective film to a polarizer according to claim 1, which is saponificated.

### Claim 8

A polarizer produced by the method for producing a polarizer comprising alkali-saponifying a protective film to a polarizer containing a cellulose acylate and an organic acid having an octanol/water partition coefficient of at least 3.0 and satisfying one of the following requirements:
(1): The surface of the film has a pH of from 3.0 to 4.5; or
(2): The surface of the film has a pH of more than 4.5 and at most 6.0, and
wherein the film has a moisture permeability of at least 2800 g/m2 ·day,
and including washing the alkali-saponified protective film to a polarizer with water, and laminating the washed protective film to a polarizer on at least one surface of a polarizing element,
the protective film to a polarizer comprising an organic acid represented by the following formula (1), wherein the ratio of the organic acid to the cellulose acylate is from 0.01 to 10% by mass:
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 9

A polarizer comprising a polarizing element and at least one sheet of a protective film to a polarizer containing a cellulose acylate and an organic acid having an octanol/water partition coefficient of at least 3.0 and satisfying one of the following requirements:
(1): The surface of the film has a pH of from 3.0 to 4.5; or
(2): The surface of the film has a pH of more than 4.5 and at most 6.0, and
wherein the film has a moisture permeability of at least 2800 g/m2 ·day,
the protective film to a polarizer comprising an organic acid represented by the following formula (1), wherein the ratio of the organic acid to the cellulose acylate is from 0.01 to 10% by mass:
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 10

A liquid crystal display device comprising at least one sheet of a protective film to a polarizer containing a cellulose acylate and an organic acid having an octanol/water partition coefficient of at least 3.0 and satisfying one of the following requirements:
(1): The surface of the film has a pH of from 3.0 to 4.5; or
(2): The surface of the film has a pH of more than 4.5 and at most 6.0, and
wherein the film has a moisture permeability of at least 2800 g/m2 ·day,
the protective film to a polarizer comprising an organic acid represented by the following formula (1), wherein the ratio of the organic acid to the cellulose acylate is from 0.01 to 10% by mass:
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 11

A polarizer comprising:
a polarizing element and two protective films to a polarizer disposed on both sides of the polarizing element,
wherein the pH of the aqueous solution of the polarizing element, as measured according to the following method (1), is from 4 to 7, and before and after aged at 60° C. and a relative humidity of 95% for 500 hours, the pH change in the aqueous solution of the polarizing element, as measured according to the following method (1), is less than 0.4, and
wherein at least one protective film to the polarizer contains an organic acid having an octanol/water partition coefficient of at least 3.0,
Method (1): 40 mg of the polarizing element is dipped in 15 ml of pure water and heated at 100° C. for 2 hours, and then the pH of the aqueous solution is measured,
wherein the organic acid is a compound represented by the following formula (1):
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 12 (depends on 11)

The polarizer according to claim 11, wherein at least one protective film to a polarizer contains a resin and the organic acid in an amount of from 0.1 to 20 parts by mass relative to 100 parts by mass of the resin.

### Claim 13 (depends on 11)

The polarizer according to claim 11, wherein X in the formula (1) represents a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphate group, a sulfonimide group or an ascorbic acid group.

### Claim 14 (depends on 11)

The polarizer according to claim 11, wherein L in the formula (1) represents a single bond or a di- or more valent linking group selected from the following units, or a di- or more valent linking group formed by combining any of these units:
Unit: —O—, —CO—, —N(R2)— wherein R2 represents an alkyl group having from 1 to 5 carbon atoms, —CH(OH)—, —CH2—, —CH═CH—, —SO2—.

### Claim 15 (depends on 11)

The polarizer according to claim 11, wherein the organic acid represented by the formula (1) comprising a structure in which one molecule of a fatty acid and one molecule of a poly carboxylic acid bond to one molecule of a polyalcohol by ester bond, and the structure has at least one unsubstituted carboxyl group derived from the poly carboxylic acid.

### Claim 16 (depends on 11)

The polarizer according to claim 11, wherein the organic acid represented by the formula (1) is a carboxylic acid derivative represented by the following formula (2):
wherein:
s and t each independently represent 1, 2 or 3;
R4 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an acyl group, an alkoxycarboxyl group, a carbamoyl group, an alkylsulfonyl group, an aryl sulfonyl group or a heterocyclic group, and each group may have a substituent, with the proviso that R4 includes the moiety of R1 in the formula (1).

### Claim 17 (depends on 11)

The polarizer according to claim 11, wherein the protective film to a polarizer comprising cellulose acylate.

### Claim 18 (depends on 17)

The polarizer according to claim 17, wherein a total acyl substitution degree of the cellulose acylate is from 2.0 to 2.97.

### Claim 19

A liquid crystal display device comprising:
at least one of the polarizer, having a polarizing element and two protective films to a polarizer disposed on both sides of the polarizing element,
wherein the pH of the aqueous solution of the polarizing element, as measured according to the following method (1), is from 4 to 7, and before and after aged at 60° C. and a relative humidity of 95% for 500 hours, the pH change in the aqueous solution of the polarizing element, as measured according to the following method (1), is less than 0.4, and
wherein at least one protective film to the polarizer contains an organic acid having an octanol/water partition coefficient of at least 3.0,
Method (1): 40 mg of the polarizing element is dipped in 15 ml of pure water and heated at 100° C. for 2 hours, and then the pH of the aqueous solution is measured,
wherein the organic acid is a compound represented by the following formula (1):
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less:
L represents a single bond, or a di- or more valent linking group:
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent:
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 20

A polarizer comprising:
a polarizing element and at least one protective film to a polarizer and having, between the polarizing element and the protective film to a polarizer, a layer containing an organic acid of the following formula (1) in an amount of from 0.01 to 10 g/m2,
wherein at least one protective film to the polarizer contains an organic acid having an octanol/water partition coefficient of at least 3.0,
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by:
(the valent number of L)-1
when L is a di- or more valent linking group.

### Claim 21 (depends on 20)

The polarizer according to claim 20, wherein R1 in the formula (1) represents a an alkyl group having from 8 to 24 carbon atoms, an alkenyl group having from 8 to 24 carbon atoms or an alkynyl group having from 8 to 24 carbon atoms, and each group may have a substituent.

### Claim 22 (depends on 20)

The polarizer according to claim 20, wherein R1 in the formula (1) represents a straight chain alkyl group having from 10 to 24 carbon atoms, a straight chain alkenyl group having from 10 to 24 carbon atoms.

### Claim 23 (depends on 20)

The polarizer according to claim 20, wherein X in the formula (1) represents a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphate group, a sulfonimide group or an ascorbic acid group.

### Claim 24 (depends on 20)

The polarizer according to claim 20, wherein L in the formula (1) represents a single bond or a di- or more valent linking group selected from the following units, or a di- or more valent linking group formed by combining any of these units:
Unit: —O—, —CO—, —N(R2)— wherein R2 represents an alkyl group having from 1 to 5 carbon atoms, —CH(OH)—, —CH2—, —CH═CH—, —SO2—.

### Claim 25 (depends on 20)

The polarizer according to claim 20, wherein the organic acid represented by the formula (1) comprising a structure in which one molecule of a fatty acid and one molecule of a poly carboxylic acid bond to one molecule of a polyalcohol by ester bond, and the structure has at least one unsubstituted carboxyl group derived from the poly carboxylic acid.

### Claim 26 (depends on 20)

The polarizer according to claim 20, wherein the molecular weight of the organic acid is from 200 to 1000.

### Claim 27 (depends on 20)

The polarizer according to claim 20, wherein the layer containing an organic acid of formula (1) in an amount of 0.01 to 10 g/m2 is an adhesive layer containing fine particles of a metal compound.

### Claim 28 (depends on 27)

The polarizer according to claim 27, wherein the fine particles of a metal compound are of metal oxides.

### Claim 29 (depends on 20)

The polarizer according to claim 20, wherein the layer containing an organic acid of formula (1) in an amount of 0.01 to 10 g/m2 is an ultraviolet curable adhesive layer.

### Claim 30

A liquid crystal display device comprising:
at least one of the polarizer having at least one protective film to a polarizer and having, between the polarizing element and the protective film to a polarizer, a layer containing an organic acid of the following formula (1) in an amount of from 0.01 to 10 g/m2,
wherein at least one protective film to the polarizer contains an organic acid having an octanol/water partition coefficient of at least 3.0,
X-L-(R1)n Formula (1)
wherein:
X represents an acid group wherein the acid dissociation constant is 5.5 or less;
L represents a single bond, or a di- or more valent linking group;
R1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a substituent;
n represents 1 when L is a single bond, or represents the number expressed by :
(the valent number of L)-1
when L is a di- or more valent linking group.