# US 10,479,870 B2 · Method for manufacturing polarizer and polarizer manufactured thereby

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- Number: US 10,479,870 B2
- Document ID: US10479870B2
- Status: Granted
- Kind: B2
- Application number: 15/572,685
- Filed: 2016-06-03
- Published: 2018-05-17
- Granted: 2019-11-19
- Earliest claimed: 2015-06-03
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Ji Young Kim; Ji Young Kim; Hye Min Yu; Kyun Il Rah; Jin Yong Park; Eungki Lee; Taek Geun Nam
- Web page: https://patentgrep.com/patent/US10479870B2

## CPC

- C08J 3/24: Crosslinking, e.g. vulcanising, of macromolecules (mechanical aspects B29C35/00; crosslinking agents C08K)
- B29D 11/00644: {polarizing}
- B32B 27/08: of synthetic resin
- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 27/308: {comprising acrylic (co)polymers}
- D06P 1/653: Nitrogen-free carboxylic acids or their salts {(sulfocarboxylic acids D06P1/626)}
- D06P 1/673: Inorganic compounds
- D06P 3/58: Material containing hydroxyl groups
- D06P 7/005: {Dyeing combined with texturising or drawing treatments}
- G02B 5/30: Polarising elements (light-modulating devices with active elements G02F1/00)
- G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid}
- B29K 2029/04: {PVOH, i.e. polyvinyl alcohol (B29K2031/04 takes precedence)}
- B32B 2307/42: Polarizing, birefringent, filtering
- C08J 2329/04: Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
- D06P 1/0076: {Dyeing with mineral dye}
- D06P 1/6533: {Aliphatic, araliphatic or cycloaliphatic}
- D06P 1/67316: {Acids}
- G02B 1/14: Protective coatings, e.g. hard coatings
- G02F 1/133528: {Polarisers}
- G02F 2201/50: Protective arrangements
- 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)
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- D06P: DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

The present specification relates to a method for manufacturing a polarizer, the method including: a step of dyeing at least one dye of iodine and dichroic dyes on a polyvinyl alcohol-based film; a first cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a first aqueous solution including a polyvalent carboxylic acid compound and a boron compound; a second cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a second aqueous solution including a polyvalent carboxylic acid compound and a boron compound; and a third cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a third aqueous solution including a polyvalent carboxylic acid compound, in which in the first cross-linking step and the second cross-linking step, stretching is performed along with cross-linking, and a polarizer manufactured by using the same.

## Claims

### Claim 1

A method for manufacturing a polarizer, the method comprising:
a step of dyeing at least one dye of iodine and dichroic dyes on a polyvinyl alcohol-based film;
a first cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a first aqueous solution including a polyvalent carboxylic acid compound and a boron compound;
a second cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a second aqueous solution including a polyvalent carboxylic acid compound and a boron compound; and
a third cross-linking step of cross-linking the polyvinyl alcohol-based film and the dye by using a third aqueous solution including a polyvalent carboxylic acid compound,
wherein in the first cross-linking step and the second cross-linking step, stretching is performed along with cross-linking.

### Claim 2 (depends on 1)

The method of claim 1, wherein a concentration index X of the polyvalent carboxylic acid compound remaining on the surface of the polyvinyl alcohol-based film after performing the third cross-linking step satisfies the following Equation (1):
0.25≤X≤0.4 Equation (1):
in Equation (1), X means a value obtained by subtracting an integral value of an absorption spectrum at 1,580 cm−1 to 1,780 cm−1, which is obtained by being measured by means of attenuated total reflection (ATR) of the polarizer subjected to the cross-linking step using an aqueous solution which does not include a polyvalent carboxylic acid compound from an integral value of an absorption spectrum at 1,580 cm−1 to 1,780 cm−1, which is obtained by being measured by means of attenuated total reflection (ATR) of the polarizer subjected to the first to third cross-linking steps.

### Claim 3 (depends on 1)

The method of claim 1, wherein the third cross-linking step is performed by using an immersion method.

### Claim 4 (depends on 1)

The method of claim 1, wherein the boron compound is each comprised in an amount of 0.5 wt % to 10 wt % based on 100 wt % of the first and second aqueous solutions.

### Claim 5 (depends on 1)

The method of claim 1, wherein the polyvalent carboxylic acid compound in the first aqueous solution and the second aqueous solution is each comprised in an amount of 10 wt % to 150 wt % based on 100 wt % of the boron compound.

### Claim 6 (depends on 1)

The method of claim 1, wherein the third aqueous solution comprises the polyvalent carboxylic acid compound in an amount of 0.5 wt % to 10 wt % based on 100 wt % of the third aqueous solutions.

### Claim 7 (depends on 1)

The method of claim 1, wherein the polyvalent carboxylic acid compounds are one or more selected from the group consisting of glutaric acid, succinic acid, malonic acid, oxalic acid, 1,2,3,4-butanetetracarboxylic acid, citric acid, malic acid, tartaric acid, and derivatives thereof.

### Claim 8 (depends on 1)

The method of claim 1, further comprising a step of drying the polyvinyl alcohol-based film after the third cross-linking step.

### Claim 9 (depends on 1)

A polarizer manufactured by the method according to claim 1.

### Claim 10 (depends on 9)

The polarizer of claim 9, comprising: a boron element in an amount of 0.5 wt % to 5 wt % based on 100 wt % of the polarizer.

### Claim 11 (depends on 9)

A polarizing plate comprising the polarizer according to claim 9.

### Claim 12 (depends on 11)

The polarizing plate of claim 11, wherein the polarizing plate has a shrinkage rate of 0.01% to 0.03% in a machine direction (MD) after a durability evaluation under a condition of being left to stand at any one temperature selected from 20° C. to 30° C. for 24 hours after the polarizing plate is left to stand at any one temperature selected from 60° C. to 70° C. for 48 hours.

### Claim 13 (depends on 12)

An image display device comprising:
a display panel; and
the polarizing plate according to claim 12, which is attached onto one surface or both surfaces of the display panel.

### Claim 14 (depends on 11)

The polarizing plate of claim 11, wherein the polarizing plate has a crack occurrence rate of 10% or less after a durability evaluation under a condition of being left to stand at any one temperature selected from 80° C. to 120° C. for 24 hours.

### Claim 15 (depends on 11)

The polarizing plate of claim 11, wherein the polarizing plate has a protective film provided on one surface of the polarizer.

### Claim 16 (depends on 15)

The polarizing plate of claim 15, wherein the protective film is provided to be brought into contact with the polarizer while an adhesive layer is provided on the other surface of the polarizer.

### Claim 17 (depends on 11)

An image display device comprising:
a display panel; and
the polarizing plate according to claim 11, which is attached onto one surface or both surfaces of the display panel.