Siloxane polyphotoinitiators of the substituted acetophenone type

摘要

An organopolysiloxane photoinitiator having an average of at least two siloxane units, of which at least an average of one siloxane unit per organopolysiloxane molecule has the formula: XaRbSiO(4-a-b)/2 wherein a is an integer of 1-3, b is a integer of 0-2 and a plus b equals 1-3; R is C1-C10 hydrocarbyl or halogen substituted C1-C10 hydrocarbyl; and X is substituted acetophenone photomoiety of the formula: where R1 is any substitutent which will not interfere with hydrosilation, n is an integer between 0 and 4; R2 is organosilyl substituted alkyl or alkenyl; R3 is H, alkyl or aryl; and R4 is a divalent hydrocarbon group having between 2 and 10 carbon atoms. The silicones are prepared by hydrosilation of the corresponding olefinically or acetylenically alpha , alpha -dialkenylacetophenones or alpha , alpha -dialkynylacetophenones.