GB360482A - Improvements in or relating to the manufacture of abrasive articles - Google Patents

Abstract

A composition for making a moulded abrasive article by vulcanization consists of a mixture of abrasive grains, a filler such as carbon black, and an aqueous dispersion of rubber containing a protective colloid which is dried to a moisture content of 5 to 7 per cent and then granulated. Other materials which may be added to the mix are magnesia, lead acetate, and a preservative such as formaldehyde or borax. The resulting dried product can be stored and moulded at any time. In moulding, the mould is filled and heated to about 287 DEG F., and may be subjected to an initial moderate pressure followed by a short interval of high pressure, after which a lower pressure is maintained until partly vulcanized. After this partial vulcanization, or "set-cure," the article is removed from the mould and vulcanized. The high pressure may be maintained during the whole of the "set-cure". In an example, 92 parts of abrasive grain of 16 grit, including a filler, are mixed with a dispersion of rubber containing a protective colloid of 8 parts (on a dry basis), and small proportions of lead acetate (10 per cent solution) and magnesium oxide added. The abrasive may be silicon carbide, alumina, garnet, &c. Specification 302,151, [Class 70. Indiarubber &c.], is referred to.