COMPOSITIONS OF RESIN-LINEAR ORGANOSILOXANE BLOCK COPOLYMERS

摘要

The present disclosure provides hydrosilylation curable compositions comprising resin linear organosiloxane block copolymers comprising, among other things, from about 0.5 to about 5 mole % C1 to C30 hydrocarbyl group comprising at least one aliphatic unsaturated bond. Such hydrosilylation curable resin-linear organosiloxane block copolymers have significantly faster cure speed, relative to their condensation curable counterparts. A faster cure speed can be important for encapsulating electronic devices, such as light-emitting diode (LED) chip devices, particularly devices having tall structures.

主权项

1. An organosiloxane block copolymer comprising:
40 to 90 mole percent disiloxy units of the formula [R12SiO2/2], 10 to 60 mole percent trisiloxy units of the formula [R2SiO3/2], 0.5 to 35 mole percent silanol groups [≡SiOH];
wherein: each R1, at each occurrence, is independently a C1 to C30 hydrocarbyl or a C1 to C30 hydrocarbyl group comprising at least one aliphatic unsaturated bond, each R2, at each occurrence, is independently a C1 to C30 hydrocarbyl or a C1 to C30 hydrocarbyl group comprising at least one aliphatic unsaturated bond;
wherein: the disiloxy units [R12SiO2/2] are arranged in linear blocks having an average of from 100 to 300 disiloxy units [R12SiO2/2] per linear block; the trisiloxy units [R2SiO3/2] are arranged in non-linear blocks having a molecular weight of at least 500 g/mole; at least 30% of the non-linear blocks are crosslinked with each other; each linear block is linked to at least one non-linear block via —Si—O—Si— linkages; the organosiloxane block copolymer has a weight average molecular weight of at least 20,000 g/mole; and the organosiloxane block copolymer comprises from about 0.5 to about 4.5 mole % C1 to C30 hydrocarbyl group comprising at least one aliphatic unsaturated bond.