Patent ID: 7268181

Claim:
A bulk-modified potting composition comprised of a curable epoxy resin or a mixture of epoxy resins, where the resin or the mixture is composed of an epoxy resin, a hardener, optionally an accelerator, and also other additives selected from the group consisting of fillers, flexibilizers, and colorants, wherein the potting composition further comprises (a) a three-dimensionally crosslinked polysiloxane in disperse form and with a particle size in the range from 0.02 μm to 50 μm, which, optionally, has reactive groups which can react chemically with the epoxy resin and/or the hardener, and (b) a selected linear or branched or cyclic polysiloxane compound which has reactive groups which can react chemically with the epoxy resin and/or the hardener, and optionally, (c) a low-molecular-weight oligomeric siloxane compound, wherein the three-dimensionally crosslinked polysiloxane (component (a)) is prepared separately in the form of a polysiloxane dispersion composed of an external phase and a dispersed phase, and is added to the epoxy potting composition or to a component of the composition prior to its curing, wherein the external phase of the polysiloxane dispersion is composed of from about 25 to 99.9% by weight of a polyol which is liquid at temperatures of from 20° C. to 100° C., a linear or branched polyether glycol, a polyester which is a reaction product of a polyol and an aliphatic dicarboxylic acid, a cycloaliphatic dicarboxylic acid, or an aromatic dicarboxylic acid, an acrylate polymer or copolymer capable of being used as a hardener in an epoxy resin system, a methacrylate polymer or copolymer capable of being used as a hardener in an epoxy resin system, or a mixture thereof.