Abstract: A process for producing a curable resin comprises reacting (a) at least one cyanate ester compound selected from the group consisting of polyfunctional cyanate esters having 2 or more cyanato groups per one molecule, prepolymers of the cyanate esters or mixtures thereof with (b) at least one compound having 1,2-epoxy group(s) and radical-polymerizable unsaturated double bond(s) in its molecule, the cyanate ester compound (a) and the compound (b) being used so that the ratio of the cyanato group to the 1,2-epoxy group is in the range of about 1:0.25 to about 1:2, in the presence of (c) a radical polymerization inhibitor at a temperature of about 90.degree.--about 140.degree. C.The curable resin produced according to the present invention is capable of giving cured products having excellent heat resistance and electrical properties.

Abstract: A curable resin composition comprising a mixture and/or a preliminary reaction product of (a) at least one cyanate compound selected from the group consisting of polyfunctional cyanate esters, prepolymers of the cyanate esters, coprepolymers of the cyanate esters and an amine and mixtures thereof, (b) a polyhydantoin resin and optionally (c) at least one maleimide compound selected from the group consisting of polyfunctional maleimides, prepolymer of the maleimides, coprepolymers of the maleimides and an amine and mixtures thereof is disclosed.

Abstract: A curable resin composition comprising a mixture and/or a preliminary reaction product of (a) at least one cyanate compound selected from the group consisting of polyfunctional cyanate esters, prepolymers of the cyanate esters, coprepolymers of the cyanate esters and an amine and mixtures thereof, (b) a polyhydantoin resin and optionally (c) at least one maleimide compound selected from the group consisting of polyfunctional maleimides, prepolymer of the maleimides, coprepolymers of the maleimides and an amine and mixtures thereof is disclosed.

Abstract: A process for producing a colloidal solution of a curable resin which comprises:blending (a) 5 to 90% by weight of a polyfunctional maleimide component and (b) 95 to 10% by weight of at least one thermosetting resin,heating them to form a composition, andblending the resulting composition with at least one low boiling point solvent having a boiling point of more than room temperature and less than 150.degree. C., in which the thermosetting resin is rich soluble, but the maleimide component is poor soluble, thereby forming a colloidal solution of a curable resin is disclosed. The colloidal solution is used as a coating, as an impregnating agent for a coil, or for preparing prepreg.

Abstract: Curable resin compositions comprising a mixture and/or a preliminary reaction product of (a) at least one cyanate compound selected from the group consisting of polyfunctional cyanate esters, prepolymers of said cyanate esters, coprepolymers of said cyanate esters and an amine and mixtures thereof and (b) a polyamideimide resin and optionally (c) at least one maleimide compound selected from the group consisting of polyfunctional maleimides, prepolymers of said maleimides, coprepolymers of said maleimides and an amine and mixtures thereof are disclosed.