| 摘要 |
505,959. Pneumatic tyres. UNITED STATES RUBBER PRODUCTS, Inc. Oct. 7, 1938, No. 29088. Convention date, Oct. 8, 1937. [Class 144 (ii)] [Also in Group V] Rubber sheet material, e.g. inner tubes for pneumatic tyres, which is resistant to tearing has a number of separations 2 each having contiguous edges defining closed paths, preferably circular paths, located over the surface of the sheet and extending partly through the thickness of the sheet. The sheet material may be made by supplying a perforated sheet of unvulcanized rubber to an unperforated sheet of unvulcanized rubber, dusting at least the perforations with soapstone, mica, or the like, and subjecting the sheets to heating and pressure so as to vulcanize them together and to cause the rubber'of the unperforated sheet to flow into the perforations of the perforate sheet. Inner tubes may be formed similarly by applying a layer of perforated unvulcanized rubber to a tubular length of unvulcanized rubber ; the separations on the surface of the inner tube may be arranged on the rim side, the outer side or all over the surface. The rubber of the perforated layer may be tougher than that of the unperforated layer. |
