GB664841A - Abrasive articles and methods of manufacturing the same - Google Patents

Abstract

Abrasive grains are bonded and/or attached to a backing by a binder comprising the reaction product of a urea-formaldehyde condensate and furfuryl alcohols. In making coated abrasive articles the said binder may constitute both the "making" and "sizing" coat or it may constitute one coat and another adhesive, e.g. hide glue or a phenol-aldehyde resin, may constitute the other. In examples: (1) abrasive discs are made by applying to a layer of cloth filled with resin a making coat containing water, an aqueous suspension of an initial urea-formaldehyde condensate, furfuryl alcohol and an accelerator comprising an ammoniacal solution of ammonium thiocyanate and thiourea. The cloth is then coated with fused alumina abrasive grain, the making coat dried, a sizing coat made by diluting the making coat with water applied, and the whole dried and cured; (2) and (3) as in (1) except that the making coat also contains respectively walnut shell flour and cryolite; (4) abrasive discs are made on a cloth backing using hide glue as the making coat and a mixture of an aqueous suspension of an initial urea-formaldehyde condensate, furfuryl alcohol, the accelerator of example (1) and walnut shell flour as the sizing coat; (5) abrasive paper is made with a glue making coat, fused alumina abrasive grain, and a mixture of an aqueous urea-formaldehyde condensate, furfuryl alcohol and the accelerator of example (1); (6) abrasive wheels are made by moulding a mixture of an aqueous urea-formaldehyde condensate, furfuryl alcohol, the accelerator of example (1), pulverized flint and abrasive grain. Instead of the accelerator of example (1) there may be used ammonium sulphate, aluminium sulphate, aluminium chloride, ferric chloride or a 20 per cent solution of ammonium thiocyanate containing ammonia. Specification 610,302 is referred to.