GB666769A - Improvements relating to moulding articles from thermo-setting resins - Google Patents

Abstract

666,769. Moulding refrigerator doors &c. from resinous material. GENERAL MOTORS CORPORATION. March 31, 1948 [April 2, 1947], No. 9076/48. Class 87(ii) [Also in Group VIII] An article which may be dish-shaped. e.g. a refrigerator door, is made by pouring a liquid thermosetting resin into a mould cavity 32 to cover the bottom 34, placing a lamina of fibrous material over the cavity to float on the resin, partly closing heated mould sections 28, 22, and then fully closing the mould to cure the resin. One section, e.g. the lower one, is at a higher temperature than the other. This higher temperature causes a gellation of a thin film of resin, during the first mould closing step, which gives the article a smooth surface. In order that pressure may be maintained on the resin during curing, a peripheral seal is provided which may be either (a) an integral metal lip 20 which also acts to cut the lamina or (b) a rubber seal, Figs. 6 and 7 (not shown). Excess resin which is not absorbed by the lamina may bleed from the mould through grooves in the lip 20 at the corners of the mould. The resin may be a mixture of alkyd polyesters and polymerizable hydrocarbons or a phenolic condensation product or a urea resin. The lamina may be sheeted glass fibre or cotton fibre. A comminuted filler may be added to give a desired surface finish. Such a filler is of spherical shape so that only small portions thereof touch the mould surfaces. The Specification as open to inspection under Sect 91 comprises also the use of polyvinyl chloride and polymethyl methacrylate resins. This subject-matter does not appear in the Specification as accepted.