GB499580A - Improvement in sponge material and method of making - Google Patents

Abstract

499,580. Sponge rubber. MISHAWAKA RUBBER & WOOLLEN MANUFACTURING CO. Aug. 11, 1938, No. 23674. Convention date, Aug. 11, 1937. [Classes 70 and 87 (ii)] [Also in Group VIII] Sponge-rubber sheet material formed with ribs or projections suitably spaced for cushioning, insulating, ornamentation &c. is made by preforming the rubber stock, containing a blowing agent, with initial formations and then heating it in an unconfined condition, i.e. not in a mould, to cause expansion and subsequent vulcanization. In an example sponge-rubber stock is formed with ribs 44, Fig. 11, by a calender roll and when heated in an unconfined condition expands to the form shown in Fig. 13. The material may be expanded and vulcanized in long lengths by feeding the stock from the calender roll through a heating chamber 42, Fig. 9, on a conveyer belt 41. A small amount of steam is introduced into the chamber, a few minutes after the beginning of the heat treatment, e.g. when the air temperature has reached 240‹ F., and the supply is continued throughout the treatment. The rubber 56, Fig. 23, may be secured to a backing 58, of fabric. In a modification, strips or pellicles of rubber stock are applied directly to fabric in spaced relation and are then heated. A mat, Fig. 24, for a motor car may comprise a tread portion 59 of solid rubber and a sponge-rubber portion 60 secured thereto, e.g. by cementing. A compound upholstery material, shown in Fig. 25, comprises a mohair layer 62, a sponge rubber layer 63 and intermediate layers 64, 65 of burlap and 66 of fibres impregnated with rubber.