CURABLE SILICONE RESINS FOR LED ENCAPSULATION

摘要

The present invention relates to a curable organopolysiloxane composition, which comprises: (A) an organocyclosiloxane having alkenyl groups, represented by the following formula (I), wherein n=3, 4 or 5; (B) a hydrosilicone resin of formula (II): (R1R2R3SiO1/2)M·(R4R5SiO2/2)D·(R6SiO3/2)T·(SiO4/2)Q, wherein R1to R5 are identical or different groups selected from organic groups and hydrogen atom, and at least one of R1to R5 is a hydrogen atom directly bonded to a silicon atom, and on average at least two hydrogen atoms directly bonded to silicon atoms are contained in one hydrosilicone resin molecule, R6 is an organic group identical to or different from R1to R5, as organic groups R1to R6 may independently be linear/branched alkyl or alkenyl groups having 1-20 carbon atoms or halides thereof; cycloalkyl groups or cycloalkenyl groups having 5-25 carbon atoms or halides thereof; M, T and Q each represents a number ranging from 0 to less than 1, 0< D <1, M+D+T+Q = 1, and T+Q > 0; and (C) platinum-based catalysts. The present invention also provides a process for preparing transparent silicone resins by hydrosilylation of tetramethyltetravinylcyclotetrasiloxane or trimethyltrivinylcyclotrisiloxane. The silicone resins obtained after curing according to the present invention have good hardness, transparency, UV stability and heat stability.