# US 5,352,759 A · Lens comprising a polycarbonate formed by an interfacial polycondensation reaction

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- Number: US 5,352,759 A
- Document ID: US5352759A
- Status: Granted
- Kind: A
- Application number: 08/013,660
- Filed: 1993-02-04
- Granted: 1994-10-04
- Earliest claimed: 1991-02-05
- Assignees: Teijin Chemicals, Ltd.
- Inventors: Toshimasa Tokuda
- Web page: https://patentgrep.com/patent/US5352759A

## CPC

- C08G 64/24: and phenols
- C08G 64/06: not containing aliphatic unsaturation
- G02B 1/041: {Lenses}
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

There is provided a polycarbonate lens having improved transmittance of light with a wavelength of 400 nm. This lens is made of a polycarbonate derived from 1,1-bis(4-hydroxyphenyl)-1-phenylethane, specific viscosity found from a solution of 0.7 g of said polycarbonate in 100 ml of methylene chloride being 0.176 to 0.295, and transmittance of light with a wavelength of 400 nm passing through a 3 mm thick member molded from said polycarbonate being 80% or more.

## Claims

### Claim 1

A lens comprising a polycarbonate formed by an interfacial polycondensation reaction of 1,1-bis(4-hydroxyphenyl)-1-phenylethane having a purity of at least 99.9% and a coloration preventing effective amount of at least one phosphorous acid ester selected from the group consisting of triphenyl phosphite and tris(4-nonylphenyl)phosphite, wherein said coloration preventing effective amount of the phosphorous acid ester is incorporated into said polycarbonate by being present during the interfacial polycondensation reaction, said polycarbonate having a specific viscosity measured in a solution of 0.7 g of said polycarbonate in 100 ml of methylene chloride at 20.degree. C. of 0.200 to 0.250, and wherein the transmittance of light having a wavelength of 400 nm passing through 3 mm thick member molded from said polycarbonate is 80% or more.

### Claim 2 (depends on 1)

The lens according to claim 1, wherein the coloration preventing effective amount is in the range of from 0.01 to 0.5% by weight based on the weight of 1,1-bis(4-hydroxyphenyl)-1-phenylethane used in the polycondensation reaction.