Compositions having low birefringence
AssigneeBayer Aktiengesellschaft
InventorsJames P. Mason, Jon M. Newcome, Jeff M. Tennant
Life of this patent
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Abstract
A thermoplastic molding composition suitable for the preparation of articles having low birefringence is disclosed. Accordingly, the composition contains polycarbonate and a polyester copolymer based on cyclohexane-dimethanol, ethylene glycol and phthalic acid. The invention resides in the findings that the incorporation of a polycarbonate resin having a melt flow index greater than 18 g/10 minutes impart to the composition low birefringence values. The composition is suitable for the preparation of optical storage media, including compact discs.
Claims26
A thermoplastic molding composition comprising
- (i) about 60 to 99 percent by weight of a polycarbonate resin, and
- (ii) about 1 to 40 percent by weight of a copolyester of phthalic acid and a mixture of cyclohexanedimethanol and ethylene glycol,
- said cyclohexane dimethanol and said ethylene glycol being present in said polyester copolymer in a molar ratio of 1:1 to 4:1 therebetween,
- said polycarbonate having a melt flow index of at least 18.0 g/10 minutes as determined in accordance with ASTM D-1238 at 300° C./under 1.2 kg load, said percent in both occurrences being relative to the total weight of said (i) and (ii).
A thermoplastic molding composition having melt flow index of at least 30 g/10 minutes, comprising
- (i) about 60 to 99 percent by weight of a polycarbonate resin, and
- (ii) about 1 to 40 percent by weight of a copolyester of phthalic acid and a mixture of cyclohexanedimethanol and ethylene glycol,
- said cyclohexane dimethanol and said ethylene glycol being present in said polyester copolymer in a molar ratio of 1:1 to 4:1 therebetween,
- said polycarbonate having a melt flow index of at least 18.0 g/10 minutes;
- said index, both occurrences, being determined in accordance with ASTM D-1238 at 300° C./under 1.2 kg load, said percent both occurrences being relative to the total weight of said (i) and (ii).
A thermoplastic molding composition having lowered birefringence values comprising
- (i) about 60 to 99 percent by weight of a polycarbonate resin, and
- (ii) about 1 to 40 percent by weight of a copolyester of phthalic acid and a mixture of cyclohexanedimethanol and ethylene glycol,
- said cyclohexane dimethanol and said ethylene glycol being present in said polyester copolymer in a molar ratio of 1:1 to 4:1 therebetween,
- said polycarbonate having a melt flow index of at least 18.0 g/10 minutes as determined in accordance with ASTM D-1238 at 300° C./under 1.2 kg load, said percent in both occurrences being relative to the total weight of said (i) and (ii), said lowered birefringence values being in comparison to the values of said polycarbonate resin.
A thermoplastic molding composition having melt flow index of at least 30 g/10 minutes and lowered birefringence values, comprising
- (i) about 60 to 99 percent by weight of a polycarbonate resin, and
- (ii) about 1 to 40 percent by weight of a copolyester of phthalic acid and a mixture of cyclohexanedimethanol and ethylene glycol,
- said cyclohexane dimethanol and said ethylene glycol being present in said polyester copolymer in a molar ratio of 1:1 to 4:1 therebetween,
- said polycarbonate having a melt flow index of at least 18.0 g/10 minutes;
- said index, both occurrences, being determined in accordance with ASTM D-1238 at 300° C./under 1.2 kg load, said percent both occurrences being relative to the total weight of said (i) and (ii) said lowered birefringence values being in comparison to the values of said polycarbonate resin.
Dependencies are inferred from the claim text.