# US 4,396,642 A · Hydrolytically stabilized polarizer

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- Number: US 4,396,642 A
- Document ID: US4396642A
- Status: Granted
- Kind: A
- Application number: 06/324,505
- Filed: 1981-11-24
- Granted: 1983-08-02
- Earliest claimed: 1981-11-24
- Assignees: American Hoechst Corporation
- Inventors: Lawrence Bolt; Michael Smith; Ali Tavasolian
- Web page: https://patentgrep.com/patent/US4396642A

## CPC

- C08J 7/123: {Treatment by wave energy or particle radiation (C08J7/18 takes precedence)}
- G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid}
- C08J 2329/04: Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
- 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)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A polarizer having increased hydrolytic stability is produced by impregnating a polyvinyl alcohol film with an iodine containing composition and then subjecting the substrate to both concentrated infrared and ultraviolet radiation treatments.

## Claims

### Claim 1

A process for producing a hydrolytically stabilized polarizer which comprises staining a polyvinyl alcohol film in a bath of an iodine containing composition and subjecting said film to concentrated sources of infrared and ultraviolet radiation, each of said radiation treatments being conducted for a period of time less than about one minute and in amounts sufficient to substantially increase the hydrolytic stability of the film.

### Claim 2 (depends on 1)

The process of claim 1 wherein said film is adhered to a support sheet either before or after said treatments.

### Claim 3 (depends on 2)

The process of claim 2 wherein said support sheet comprises a polyester.

### Claim 4 (depends on 3)

The process of claim 3 wherein said polyester support sheet comprises polyethylene terephthalate.

### Claim 5 (depends on 4)

The process of claim 4 wherein said polyethylene terephthalate has been uniaxially stretched.

### Claim 6 (depends on 5)

The process of claim 5 wherein said polyethylene terephthalate has been transversely uniaxially stretched.

### Claim 7 (depends on 2)

The process of claim 2 wherein said support sheet comprises cellulose acetate butyrate.

### Claim 8 (depends on 2)

The process of claim 2 wherein said polyvinyl alcohol film is laminated to said support sheet.

### Claim 9 (depends on 3)

The process of claim 3 wherein said polyester support is coated with a composition comprising polyvinyl alcohol or polyurethane and said support is adhered to said film via said coating.

### Claim 10 (depends on 9)

The process of claim 9 wherein an adhesion promoting agent is disposed between said polyvinyl alcohol film and said support sheet.

### Claim 11 (depends on 1)

The process of claim 1 wherein said film is subjected to a boronic stabilizing treatment prior to irradiation.

### Claim 12 (depends on 1)

The process of claim 1 wherein said film is dried prior to irradiation.

### Claim 13 (depends on 11)

The process of claim 11 wherein said film is dried after boronic stabilizing but prior to irradiation.