Provided is a curable organopolysiloxane composition from which highly heat-resistant cured products can be obtained, the curable organopolysiloxane composition comprising: (A) 100 parts by mass of a novel organopolysiloxane represented by formula (1) ##STR00001##
(R.sup.1 is an alkyl group or an alkoxy substituted alkyl group having 1 to 6 carbon atoms, R.sup.2 is a group selected from an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a group in which a portion of the hydrogen atoms of those groups is substituted with a halogen atom, Ar is an arylene group having 6 carbon atoms or more, a is 1 to 1,000, b is 1 to 5,000, and n is 1 to 3, the total of n in an unsubstituted or substituted alkoxysilyl group on both ends of the molecular chain being 3 or more); and (B) 0.01 to 10 parts by mass of a curing catalyst. Also provided are electrical and electronic components, a vehicle oil seal, a building sealant, etc. which use the cured product of the composition.

A bridged silicone resin is disclosed which has the general formula (1): (HSiO.sub.3/2).sub.x(RSiO.sub.3/2).sub.y(R.sup.1SiO.sub.3/2).sub.z(SiO.sub.3/2XSiO.sub.3/2).sub.s; wherein x and s are each from >0 to <1 and 0<y+z<1 such that x+y+z+s=1; R is independently an alkyl group; R.sup.1 is independently an aryl group; and X is divalent group comprising a silarylene group or a (CH.sub.2).sub.qSiR.sup.2R.sup.3[O(SiR.sup.2R.sup.3O).sub.n]SiR.sup.2R.sup.3(CH.sub.2).sub.q group, where n is an integer from 1 to 10, each R.sup.2 and R.sup.3 is an independently selected substituted or unsubstituted hydrocarbyl group, and q and q are each independently integers selected from 0 or from 1 to 6. Various methods relating to the bridged silicone resin and end uses thereof are also disclosed.

A bridged silicone resin is disclosed which has the general formula (1): (HSiO.sub.3/2).sub.x(RSiO.sub.3/2).sub.y(R.sup.1SiO.sub.3/2).sub.z(SiO.sub.3/2XSiO.sub.3/2).sub.s; wherein x and s are each from >0 to <1 and 0<y+z<1 such that x+y+z+s=1; R is independently an alkyl group; R.sup.1 is independently an aryl group; and X is divalent group comprising a silarylene group or a (CH.sub.2).sub.qSiR.sup.2R.sup.3[O(SiR.sup.2R.sup.3O).sub.n]SiR.sup.2R.sup.3(CH.sub.2).sub.q group, where n is an integer from 1 to 10, each R.sup.2 and R.sup.3 is an independently selected substituted or unsubstituted hydrocarbyl group, and q and q are each independently integers selected from 0 or from 1 to 6. Various methods relating to the bridged silicone resin and end uses thereof are also disclosed.

A film-forming composition includes a compound including a SiH bond and an orthoester. The compound preferably includes a structural unit that is a structural unit represented by formula (1-1), a structural unit represented by formula (1-2), or a combination thereof. In the formula (1-1) and the formula (1-2), R.sup.1 and R.sup.2 each represent a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; and R.sup.3 represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms that bonds to two Si atoms.

##STR00001##

[Problem] To provide a polysiloxanecapable of forming a cured film of a thick film with high heat resistance, a composition comprising the polysiloxane, and a method of manufacturing a cured film using the composition. [Means for Solution] To provide a polysiloxane comprising a repeating unit represented by the following formula (Ib), wherein R.sup.2 is each independently hydrogen, alkyl, aryl, alkenyl, and the like, a composition comprising the polysiloxane, and a method of manufacturing a cured film using the composition. ##STR00001##

[Problem] To provide a polysiloxanecapable of forming a cured film of a thick film with high heat resistance, a composition comprising the polysiloxane, and a method of manufacturing a cured film using the composition. [Means for Solution] To provide a polysiloxane comprising a repeating unit represented by the following formula (Ib), wherein R.sup.2 is each independently hydrogen, alkyl, aryl, alkenyl, and the like, a composition comprising the polysiloxane, and a method of manufacturing a cured film using the composition. ##STR00001##

The present invention provides a curable organosilicon resin composition showing excellent optical transparency, curability, heat resistance and light resistance. The present invention also provides a semiconductor device encapsulated with a cured product of such a composition. According to the invention, the curable organopolysiloxane composition comprises: (A) an organopolysiloxane comprising at least 10 mol %, based on total moles of siloxane units, of a siloxane unit of the following formula (1): ##STR00001##
wherein R.sup.1 is, independently at each occurrence, a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R.sup.2 is a divalent aromatic group having 6 to 50 carbon atoms and optionally comprising a silylene group or a siloxane linkage, and 10 to 90 mol % of R.sup.1SiO.sub.3/2 unit, the organopolysiloxane having a weight average molecular weight (Mw) of from 2,000 to 100,000, as determined by gel permeation chromatography relative to polystyrene standards, and a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of at least 1.5; and (B) a catalytic amount of a basic catalyst.

The present invention provides a curable organosilicon resin composition showing excellent optical transparency, curability, heat resistance and light resistance. The present invention also provides a semiconductor device encapsulated with a cured product of such a composition. According to the invention, the curable organopolysiloxane composition comprises: (A) an organopolysiloxane comprising at least 10 mol %, based on total moles of siloxane units, of a siloxane unit of the following formula (1): ##STR00001##
wherein R.sup.1 is, independently at each occurrence, a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R.sup.2 is a divalent aromatic group having 6 to 50 carbon atoms and optionally comprising a silylene group or a siloxane linkage, and 10 to 90 mol % of R.sup.1SiO.sub.3/2 unit, the organopolysiloxane having a weight average molecular weight (Mw) of from 2,000 to 100,000, as determined by gel permeation chromatography relative to polystyrene standards, and a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of at least 1.5; and (B) a catalytic amount of a basic catalyst.

A bridged silicone resin is disclosed which has the general formula (1): (HSiO.sub.3/2).sub.x(SiO.sub.3/2XSiO.sub.3/2).sub.y(1); wherein x and y are each from >0 to <1 such that x+y=1; and wherein X is divalent group comprising a silarylene group or a (CH.sub.2).sub.qSiRR.sup.1[O(SiRR.sup.1O).sub.n]SiRR.sup.1(CH.sub.2).sub.q group, where n is an integer from 1 to 10, each R and R.sup.1 is an independently selected substituted or unsubstituted hydrocarbyl group, and q and q are each independently integers selected from 0 or from 1 to 6. Various methods relating to the bridged silicone resin and end uses thereof are also disclosed.

A bridged silicone resin is disclosed which has the general formula (1): (HSiO.sub.3/2).sub.x(SiO.sub.3/2XSiO.sub.3/2).sub.y(1); wherein x and y are each from >0 to <1 such that x+y=1; and wherein X is divalent group comprising a silarylene group or a (CH.sub.2).sub.qSiRR.sup.1[O(SiRR.sup.1O).sub.n]SiRR.sup.1(CH.sub.2).sub.q group, where n is an integer from 1 to 10, each R and R.sup.1 is an independently selected substituted or unsubstituted hydrocarbyl group, and q and q are each independently integers selected from 0 or from 1 to 6. Various methods relating to the bridged silicone resin and end uses thereof are also disclosed.