GB479353A - Process and apparatus for treating natural cork and the like - Google Patents

Abstract

479,353. Treating cork. CORCHERA INTERNACIONAL SOC. ANON. July 31, 1936, No. 21283. Convention date, July 31, 1935. [Class 140] [Also in Group V] Pitted natural cork is treated by coating the surface of the pits with an adhesive film and thereafter filling the pits, while the adhesive coating is tacky, with a composition comprising finely-divided cork particles and a binder. The adhesive film may be set and then rendered tacky by heat, solvent or chemical action prior to the application of the filling composition. The adhesive may be solid, liquid or plastic. The filling-composition may be a liquid or paste but preferably consists of cork dust coated with a film of the binder, which may be set and subsequently rendered tacky prior to use. Discs of cork are washed, bleached, acidified with oxalic acid, again washed and dried in apparatus A. The adhesive is then applied, by dipping, in chamber B, but spreading or spraying may be used. Preferably the discs are submitted to a vacuum treatment before dipping followed by pressure during dipping. A rotary extractor C removes excess adhesive and the filling composition is applied in a rotary cylinder D, excess being removed in a rotating, perforated cylinder E. Additional powdered cork is applied in a cylinder E1 to absorb excess adhesive and to polish the product. The discs are then given a washing-bleaching-acid treatment in apparatus F similar to apparatus A and are passed through an over G to set or vulcanize the binder, or they may be passed through the oven before washing &c.