Title:
OPTICAL DISK SUBSTRATE
Document Type and Number:
WIPO Patent Application WO/1997/022649
Kind Code:
A1
Abstract:
An optical disk substrate made from a polycarbonate resin prepared from at least one dihydric phenol selected from the group consisting of 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, and 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, the dihydric phenol amounting to 30 to 100 % by mole of the whole dihydric phenol component. The number of unacceptable surface irregularities of the substrate is 0 to 1, and the polycarbonate resin satisfies the requirements that (A) the specific viscosity measured as a solution of 0.7 g of the resin in 100 ml of methylene chloride at 20 �C is 0.2 to 0.4; (B) the number of insoluble particles measured as a solution of the polycarbonate resin in methylene chloride is not more than 25,000 per g of the polycarbonate resin in terms of the number of particles having an equivalent diameter of not less than 0.5 'mu'm and not more than 500 per g of the polycarbonate resin in terms of the number of particules having an equivalent diameter of not less than 1 'mu'm; and (C) the water absorption is not more than 0.2 % by weight. This substrate enables pits or grooves to be accurately transferred, is less likely to cause warpage derived from absorption of moisture, and has a high-density recording capacity. It has high functions suitable particularly for use as an optical disk substrate for video disks or the like.
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Inventors:
TOKUDA TOSHIMASA (JP)
Application Number:
PCT/JP1996/003616
Publication Date:
June 26, 1997
Filing Date:
December 11, 1996
Export Citation:
Assignee:
TEIJIN CHEMICALS LTD (JP)
TOKUDA TOSHIMASA (JP)
TOKUDA TOSHIMASA (JP)
International Classes:
C08G64/06; G11B7/253; (IPC1-7): C08G64/06; C08K5/06; C08K5/51; C08L69/00; G11B7/24
Foreign References:
| JPH08293128A | 1996-11-05 | |||
| JPS6389529A | 1988-04-20 | |||
| JPS6389540A | 1988-04-20 | |||
| JPH02219855A | 1990-09-03 | |||
| JPH0839545A | 1996-02-13 | |||
| JPS62186201A | 1987-08-14 |
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