Intrinsically low birefringent molding polymers have a molten stress optic coefficient that is greater than or equal to -1000 Brewsters and less than or equal to +1000 Brewsters, a glass transition temperature of at least 140°C, and a water absorption
according to ASTM D570-81 after 24 hours immersion in water at 23°C) of less than 0.25 percent and comprise in polymerized form at least one structural component providing a positive melt homopolymer stress optic coefficient and at least one other structural component providing a negative melt homopolymer stress optic coefficient. They are particularly useful as substrates for optical storage discs.
本征低双折射模塑聚合物的熔融应力光学系数大于或等于-1000布鲁斯特,小于或等于+1000布鲁斯特,
玻璃化转变温度至少为140°C,吸
水率(根据ASTM D570-81标准,在23°C
水中浸泡24小时后的吸
水率)小于0.25%。
根据 ASTM D570-81,在 23°C
水中浸泡 24 小时后的吸
水率小于 0.25%),并包含至少一种具有正熔融均聚物应力光学系数的聚合结构组分和至少一种具有负熔融均聚物应力光学系数的其他结构组分。它们特别适用于作为光存储光盘的基材。