| abstract |
A grease composition used for assisting radiation of heat from electronic devices or machines comprises, by weight, (1) 100 parts of a photocurable organopolysiloxane having a viscosity at 25 DEG C of 0.5 - 1000 m<2>.s<-><1> (50-100,000 cSt) and (i) represented by the general formula R<1>aR<2>bR<3> cSiO(a+b+c))/2 where a, b and c are defined respectively by 0.01 <a,b< 0.1 and 1.9 <c< 2.0, R<1> is a monofunctional mercaptaolkyl group represented by -(-CH2)nSH wherein n is 1 - 8 (preferably 3), R<2> is a monofunctional hydrocarbon group containing a C2-8 aliphatic unsaturated group (e.g. vinyl), and R<3> is an optionally substituted (e.g. halogenated) monofunctional C1-18 hydrocarbon group and/or (ii) a combination of organopolysiloxanes each of said viscosity and one containing at least 2 mercaptoalkyl groups as defined for R<1> and another containing at least 2 monofunctional hydrocarbon groups as defined for R<2>, (2) 100-900 (preferably 150-400) parts of a thickener which is a powdered inorganic compound having good heat conductivity, e.g. ZnO, Al2O3, AlN, BN or SiC, and optionally (3) a curing accelerator or photosensitizer. The mixed composition readily cures in natural or artificial light. It is used to assist removal of heat generated in the use of electronic components used in electrical applicances, audio systems and industrial equipment; the grease which is squeezed or bled to the exterior is there photocured and does not soil the surrounding area. |