Disclosed is a curable organopolysiloxane composition, comprising: (A) a curing reactive organopolysiloxane component formed by curing or semi-curing and reacting at least two or more types of organopolysiloxanes in the presence of one or more types of catalysts; and (B) a peroxide. The composition is a non-fluid at 25° C., and the melt viscosity at 100° C. is 8000 Pa.Math.s or lower. A sealing agent comprising the curable organopolysiloxane composition and a cured product of the curable organopolysiloxane composition are also disclosed, along with a method of molding a cured product and a semiconductor device comprising the cured product.

Disclosed is a curable organopolysiloxane composition, comprising: (A) a curing reactive organopolysiloxane component formed by curing or semi-curing and reacting at least two or more types of organopolysiloxanes in the presence of one or more types of catalysts; and (B) a peroxide. The composition is a non-fluid at 25° C., and the melt viscosity at 100° C. is 8000 Pa.Math.s or lower. A sealing agent comprising the curable organopolysiloxane composition and a cured product of the curable organopolysiloxane composition are also disclosed, along with a method of molding a cured product and a semiconductor device comprising the cured product.

A resin composition having all of higher pigment colorability, low-temperature impact resistance, and flame retardance is provided. A graft copolymer is a polyorganosiloxane-containing graft copolymer formed by polymerizing one or more grafting vinyl monomers (b) in the presence of a rubber (A) containing polyorganosiloxane and a vinyl polymer, wherein the index of refraction of the rubber (A) is in the range of 1.47 to 1.56, and the volume-average particle size is in the range of 300 nm to 2000 nm. A resin composition contains the graft copolymer and a resin.

A resin composition having all of higher pigment colorability, low-temperature impact resistance, and flame retardance is provided. A graft copolymer is a polyorganosiloxane-containing graft copolymer formed by polymerizing one or more grafting vinyl monomers (b) in the presence of a rubber (A) containing polyorganosiloxane and a vinyl polymer, wherein the index of refraction of the rubber (A) is in the range of 1.47 to 1.56, and the volume-average particle size is in the range of 300 nm to 2000 nm. A resin composition contains the graft copolymer and a resin.

Disclosed is an impact strength modifier (α) for a chlorine-containing resin, comprising a powder of a graft copolymer (A) obtained by graft polymerizing one or more kinds of vinyl monomers (b1) onto a polyorganosiloxane rubber (A1) or a composite rubber (A2) containing a polyorganosiloxane rubber and a polyalkyl (meth)acrylate rubber, wherein the specific surface area of the powder of the graft copolymer (A) measured by a nitrogen gas adsorption method is from 0.6 to 30 m.sup.2/g, and the pH of water used for extraction under conditions, in which (1) in an oven at 180° C., 5.0 g of the powder of the graft copolymer (A) is left to stand still and heated for 15 minutes, and (2) after the heating, the powder is dispersed in 100 ml of heated pure water and extracted for 1 hour at 70° C. while stirring, is from 4 to 11.

Disclosed is an impact strength modifier (α) for a chlorine-containing resin, comprising a powder of a graft copolymer (A) obtained by graft polymerizing one or more kinds of vinyl monomers (b1) onto a polyorganosiloxane rubber (A1) or a composite rubber (A2) containing a polyorganosiloxane rubber and a polyalkyl (meth)acrylate rubber, wherein the specific surface area of the powder of the graft copolymer (A) measured by a nitrogen gas adsorption method is from 0.6 to 30 m.sup.2/g, and the pH of water used for extraction under conditions, in which (1) in an oven at 180° C., 5.0 g of the powder of the graft copolymer (A) is left to stand still and heated for 15 minutes, and (2) after the heating, the powder is dispersed in 100 ml of heated pure water and extracted for 1 hour at 70° C. while stirring, is from 4 to 11.

A block copolymer including a first block consisting of a polymer having a repeating structure of a structural unit (u1) containing no silicon atom, and a second block consisting of a polymer having a repeating structure of a structural unit (u2) containing a silicon atom, the second block containing a block (b21) consisting of a polymer having a repeating structure represented by general formula (u2-1), and a block (b22) consisting of a polymer having a repeating structure of a structural unit (u22) containing a silicon atom, and the block (b22) is positioned between the first block and the block (b21) (wherein R.sup.P211 represents an alkyl group, a halogenated alkyl group, a hydrogen atom, or an organic group having a polar group; and R.sup.P212 represents an organic group having a polar group). ##STR00001##

A block copolymer including a first block consisting of a polymer having a repeating structure of a structural unit (u1) containing no silicon atom, and a second block consisting of a polymer having a repeating structure of a structural unit (u2) containing a silicon atom, the second block containing a block (b21) consisting of a polymer having a repeating structure represented by general formula (u2-1), and a block (b22) consisting of a polymer having a repeating structure of a structural unit (u22) containing a silicon atom, and the block (b22) is positioned between the first block and the block (b21) (wherein R.sup.P211 represents an alkyl group, a halogenated alkyl group, a hydrogen atom, or an organic group having a polar group; and R.sup.P212 represents an organic group having a polar group). ##STR00001##

A resin molded product includes: (I) a thermoplastic urethane resin: 80 to 99.9% by weight; and (II) a silicone acrylic graft copolymer resin: 0.1 to 20% by weight, the silicone acrylic graft copolymer resin comprising: (A) an organopolysiloxane represented by the specific formula; and (B) an acrylic ester unit or a methacrylic ester unit, wherein a weight ratio of these components is (A):(B)=50:50 to 90:10.

A graft copolymer capable of providing impact resistance, flame retardance, and color rendering properties to a thermoplastic resin is described. The graft copolymer contains a polyorganosiloxane, and is obtained by graft-polymerizing vinyl monomers including a (meth)acrylate ester (b.sub.1) having an alkyl group or an aromatic group and an aromatic vinyl monomer (b.sub.2) on a polyorganosiloxane-based rubber. The graft copolymer has a volume average particle diameter of 200-2000 nm, and contains 0.1-69 mass % of polyorganosiloxane. A thermoplastic resin composition is also described, containing a thermoplastic resin (A), the graft copolymer, a fluorine resin (C) and a flame retardant (D). A molded article is also described, which is obtained by molding the thermoplastic resin composition.