| 摘要 |
PROBLEM TO BE SOLVED: To obtain a disk substrate having little cracks during forming, small double refraction and excellent transfer property by specifying the structural units and compounding ratios of polycarbonate and polyorganosiloxane as the compsn. of a digital video disk substrate. SOLUTION: This substrate contains 5 to 100wt.% polycarbonate- polyorganosiloxane copolymer comprising a polycarbonate structural unit expressed by formula I and a polyorganosiloxane structural unit expressed by formula II, and 95 to 0wt.% polycarbonate resin. Moreover, the resin compsn. contains 0.1 to 10wt.% polyorganosiloxane structural unit to the whole amt. of the resin compsn. In formula I, R<1> , R<2> are independently halogen atoms or 1 to 6C alkyl groups or phenyl groups. In formula II, R<3> to R<6> are independently 1 to 6C alkyl groups or phenyl groups. |
