Abstract: A curable composition includes (A) silica fine particles surface-modified with at least one silane compound including at least (A1) a polymerizable silane compound of the general formula (1), (B) a (meth)acrylate compound, and (C) a polymerization initiator, SiR1aR2bR3c(OR4)4-a-b-c??(1) wherein R1 is a C11-20 hydrocarbon group having an ethylenic unsaturated group, or a substituted C11-20 hydrocarbon group having an ethylenic unsaturated group and having an ether bond and/or an ester bond; R2 is a hydrogen atom or a C1-4 hydrocarbon group; R3 is a halogen atom; R4 is a hydrogen atom or a C1-10 hydrocarbon group; a is an integer of 1 to 3; b is an integer of 0 to 2; c is an integer of 0 to 3; the sum of a and b is 1 to 3; the sum of a, b and c is 1 to 4.

Abstract: A curable composition includes (A) silica fine particles surface-modified with at least one silane compound including at least (A1) a polymerizable silane compound of the general formula (1), (B) a (meth)acrylate compound, and (C) a polymerization initiator, SiR1aR2bR3c(OR4)4-a-b-c??(1) wherein R1 is a C11-20 hydrocarbon group having an ethylenic unsaturated group, or a substituted C11-20 hydrocarbon group having an ethylenic unsaturated group and having an ether bond and/or an ester bond; R2 is a hydrogen atom or a C1-4 hydrocarbon group; R3 is a halogen atom; R4 is a hydrogen atom or a C1-10 hydrocarbon group; a is an integer of 1 to 3; b is an integer of 0 to 2; c is an integer of 0 to 3; the sum of a and b is 1 to 3; the sum of a, b and c is 1 to 4.

Abstract: The present invention provides a curable composition, wherein a cured material obtainable by curing the curable composition has excellent transparency, thermal durability and surface hardness and has a small Abbe number. In particular, the present invention provides a curable composition containing (a) silica fine particles; (b) a (meth)acrylate compound having two or more ethylenically unsaturated groups; (c) a (meth)allyl compound having two or more ethylenically unsaturated groups and having an aromatic ring structure; and (d) a polymerization initiator; wherein the surface of the silica fine particles (a) has been treated with a specified silane compound (e) and a specified silane compound (f).

Abstract: An object of the present invention is to provide a reactive urethane compound having superior curability, adhesion to substrates, transparency, molecular flexibility, and mechanical properties, a curable composition containing the compound, and a cured material formed from the composition. An ethylenically-unsaturated-group containing reactive urethane compound of the present invention is represented by formula (I): wherein R1 and R2 are each independently a hydrogen atom or an alkylene group; R3 is a hydrogen atom, a alkyl group, or an aryl group; R4 is a single bond or an alkylene group; R5 is a hydrogen atom or a methyl group; R6 is an oxygen atom, a sulfur atom, or an imino group; n is 2 to 12; m is 1 to 300; and X is an aliphatic, aromatic or heterocyclic compound residue.

Abstract: It is an object of the present invention to provide an epoxy resin curing agent which has a favorable pot life and good storage stability as a curing agent for epoxy resins and from which an epoxy resin cured product having good water resistance and hardness is obtained through curing. The present invention is an epoxy resin curing agent containing a secondary or tertiary branched thiol compound having a substituent on a carbon atom at the ?-position to a thiol group, and is also an epoxy resin composition comprising a polyvalent epoxy compound and the epoxy resin curing agent.

Abstract: The present invention provides a curable composition having a proper viscosity and excellent handling properties, and a cured product that is obtainable by curing the curable composition and has excellent transparency, heat resistance and resistance to environment and a low Abbe's number, and further can effectively decrease chromatic aberration by the combined use with a material having a high Abbe's number. The curable composition is characterized by comprising (a) silica fine particles, (b) a (meth)acrylate compound having at least two ethylenic unsaturated groups and having no ring structure, (c) a (meth)acrylate compound having at least two ethylenic unsaturated groups and having an aromatic ring structure and (d) a polymerization initiator, wherein the silica particles (a) are surface treated by a specific silane compound (e) and a specific silane compound (f).

Abstract: Disclosed is a (meth)acrylate compound which can provide a cured article having a high refractive index and excellent transparency and heat resistance, and which has superior handling characteristics; further disclosed are a curable composition containing the (meth)acrylate compound, and a cured article thereof. The (meth)acrylate compound contains an aromatic group represented by the following general formula (1), the curable composition comprising the aromatic-group containing (meth)acrylate compound, and the cured article thereof. (In the formula, R1, R2, R3 and R4 are each independently a hydrogen atom or a methyl group; X is an organic group having an aromatic group and 6 to 30 carbon atoms; and a and b are each independently an integer of 0 to 3.

Abstract: It is an object of the present invention to provide an epoxy resin curing agent which has a favorable pot life and good storage stability as a curing agent for epoxy resins and from which an epoxy resin cured product having good water resistance and hardness is obtained through curing. The present invention is an epoxy resin curing agent containing a secondary or tertiary branched thiol compound having a substituent on a carbon atom at the ?-position to a thiol group, and is also an epoxy resin composition comprising a polyvalent epoxy compound and the epoxy resin curing agent.

Abstract: It is an object of the present invention to provide a curable composition having excellent curability and capable of forming a cured film which is excellent in surface hardness, scratch resistance, flexibility, bending property, transparency and curling property, and a cured product thereof. The curable composition of the present invention is characterized by comprising (A) a urethane compound represented by the following general formula (1), (B) a thiol compound and (C) a polymerization initiator.

Abstract: An object of the present invention is to provide a reactive urethane compound having superior curability, adhesion to substrates, transparency, molecular flexibility, and mechanical properties, a curable composition containing the compound, and a cured material formed from the composition. An ethylenically-unsaturated-group containing reactive urethane compound of the present invention is represented by formula (I): wherein R1 and R2 are each independently a hydrogen atom or an alkylene group; R3 is a hydrogen atom, a alkyl group, or an aryl group; R4 is a single bond or an alkylene group; R5 is a hydrogen atom or a methyl group; R6 is an oxygen atom, a sulfur atom, or an imino group; n is 2 to 12; m is 1 to 300; and X is an aliphatic, aromatic or heterocyclic compound residue.

Abstract: It is an object of the present invention to provide a urethane compound capable of providing a cured product which is excellent in surface hardness, scratch resistance, flexibility and bending property, has reduced curling property and also has good transparency, a curable composition containing the same and a cured product thereof. The curable composition of the present invention is characterized by containing a specific urethane compound having an isocyanurate ring skeleton and a polymerization initiator.