Patent ID: 8921492

Claim:
A modified reaction resin formed as an emulsion or dispersion with high storage stability, comprising: a) from 40-98% by weight of at least one cyanate ester with at least two cyanate groups that are cross-linkable with each other or that are polymerizable to form cyanate ester prepolymers that are cross-linkable with each other, without a release of volatile substances, wherein the modified reaction resin contains no other organic monomers or organic prepolymers except for said cyanate ester monomers or said cyanate ester prepolymers; b) from 2-60% by weight of at least one polyorganosiloxane that is a finely distributed particulate dispersed throughout the modified reaction resin; c) from 2-20% by weight of at least one dispersing agent for forming the storage stable emulsion or dispersion of the at least one polyorganosiloxane or a precatalyzed polyorganosiloxane in the modified reaction resin; and d) a cross-linker for said polyorganosiloxane, wherein said cross-linker comprises any of the group consisting of polyorganohydrogensiloxane, methyltriacetoxysilane, tetraethoxysilane and methyl-tris-(methylethylketoximino)-silane; wherein said at least one dispersing agent has an amphiphilic structure, in which a portion of the groups of such amphiphilic molecules is selected such that it is compatible with the polyorganosiloxane that is used, while another portion of the groups is selected such that it is compatible with the cyanate ester; wherein said at least one dispersing agent is a copolymer of at least one polymethylsiloxane and at least one polyether, and said at least one polyether includes ethoxy units and/or propoxy units; and, wherein said copolymer of said at least one polymethylsiloxane and said at least one polyether comprises 25% by weight of a polydimethylsiloxane, wherein said ethoxy units and said propoxy units are present in a weight ratio of 40 to 60, and wherein said copolymer has a viscosity of 2,000 to 4,000 mPas at 25° C.