Molding compositions
AssigneeHenkel Corporation
InventorCharles S. Bischof
Life of this patent
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Abstract
A curable composition exhibiting excellent moldability without mold staining or delamination is provided, including an epoxy resin, a curing agent for the epoxy resin, and a polyphenylene oxide compound having a glass transition temperature between about 165° C. and about 190° C. The polyphenylene oxide compound may be provided as a melt blended mixture of two polyphenylene oxide compounds having distinct glass transition temperatures. The curable compositions may further include a bulk filler, and are therefore particularly useful as molding compounds encapsulation of electrical and/or electronic parts in transfer molding operations.
Claims20
A curable composition comprising:
- an epoxy resin;
- a curing agent for promoting curing of the epoxy resin;
- and
- a polyphenylene oxide component comprising a melt blended mixture of at least two different polyphenylene oxide compounds having different glass transition temperatures, wherein the at least two different polyphenylene oxide compounds are melt blended in the absence of the epoxy resin,
- wherein the glass transition temperature of a first polyphenylene oxide compound is below about 200° C., and the glass transition temperature of a second polyphenylene oxide compound is above about 220° C., and
- wherein the ratio of the first polyphenylene oxide compound to the second polyphenylene oxide compound is from about 3:1 to 1:1.
A method of reducing staining of mold surfaces during a transfer molding operation comprising providing an epoxy-based molding composition comprising:
- an epoxy resin;
- a curing agent for promoting curing of the epoxy resin;
- and
- a polyphenylene oxide component comprising a melt blended mixture of at least two different polyphenylene oxide compounds having different glass transition temperatures, wherein the at least two different polyphenylene oxide compounds are melt blended in the absence of the epoxy resin,
- wherein the glass transition temperature of a first polyphenylene oxide compound is below about 200° C., and the glass transition temperature of a second polyphenylene oxide compound is above about 220° C.,
- wherein the ratio of the first polyphenylene oxide compound to the second polyphenylene oxide compound is from about 3:1 to 1:1.
A method of coating an electrical or electronic device, comprising heating a molding composition to a temperature sufficient to cure the molding composition and form a polymer on the surface of the device, wherein the molding composition comprises:
- an epoxy resin;
- a curing agent for promoting curing of the epoxy resin;
- and
- a polyphenylene oxide component comprising a melt blended mixture of at least two different polyphenylene oxide compounds having different glass transition temperatures, wherein the at least two different polyphenylene oxide compounds are melt blended in the absence of the epoxy resin,
- wherein the glass transition temperature of a first polyphenylene oxide compound is below about 200° C., and the glass transition temperature of a second polyphenylene oxide compound is above about 220° C., and
- wherein the ratio of the first polyphenylene oxide compound to the second polyphenylene oxide compound is from about 3:1 to 1:1.
Dependencies are inferred from the claim text.