US 4,246,165 A · Preparation of coated casting sand using unsaturated polyester resin as binder

Abstract

A crystalline unsaturated polyester, which is a scarcely tacky solid at room temperature but at a temperature somewhat above its softening temperature assumes a fluid state with a viscosity below about 500 poises, is used as a principal component of a binder for the preparation of a resin coated casting sand for use in shell mold casting of, particularly, aluminum alloys with an aim of facilitating the disintegration of molds and cores. The binder is mixed with a conventional foundry sand at an appropriately elevated temperature in the presence of an organic peroxide as a polymerization catalyst. The binder may preferably contain a cross-linking agent such as diallyl phthalate and optionally a silane as a coupling agent and/or a cross-linking accelerator.

Claims33

Dependent claims

A process of preparing a resin coated sand for the fabrication of molds and cores for use in sand mold casting, the process comprising the step of:

mixing a major amount of a foundry sand with a minor amount of a binder composition, which comprises a crystalline unsaturated polyester as a principal component thereof, at an elevated temperature at which said binder composition is in a fluid state in the presence of an organic peroxide which serves as a polymerization catalyst for said crystalline unsaturated polyester, said crystalline unsaturated polyester having an average molecular weight of about 1000 to about 2000, said binder composition being a scarcely tacky solid at room temperature and, the viscosity of said binder composition at a temperature about 30.degree. C. above the softening temperature thereof being below about 500 poises.

Dependencies are inferred from the claim text.

Preparation of coated casting sand using unsaturated polyester resin as binder

Life of this patent

Preparation of coated casting sand using unsaturated polyester resin as binder

Life of this patent

Abstract

Claims33