PURPOSE: To obtain a copolymer comprising a polyborosilazane block formed by introducing specified boron-containing crosslinkages into a polysilazane chain and having a specified B/Si ratio and a specified thermoplastic silicon- containing polymer block and being useful as a precursor for ceramics.
CONSTITUTION: A polyborosilazane (A) formed by introducing at least any of the crosslinkages selected from among those of formulas (i) to (iv) (wherein R1 is H, a halogen, 1-20C alkyl, alkenyl, hydroxyl or the like; R2 is an R1 group bonded to the N atom of a nitrogenous group, at least two of the six atoms including three N atoms and three B atoms in formula (iv) are used for crosslinking, and the rest are sites to which R1s are bondable) into a polysilazane chain and having a B/Si atomic ratio in the range of 0.01-3 and a number-average molecular weight of 200-50000 is reacted with a thermoplastic silicon-containing polymer (B) of a number-average molecular weight of 100-50000 in an (Si in A) to (Si in B) atomic ratio of 1/50 to below 1.
AOKI TOMOKO
NAKAHARA HIROHIKO
SHIMIZU YASUO
ISODA TAKESHI
| JPH0586509A | 1993-04-06 | |||
| JPH0284437A | 1990-03-26 | |||
| JP3290463B2 | 2002-06-10 |