| 摘要 |
824,476. Permeable coated materials. DU PONT DE NEMOURS & CO., E.I. Nov. 5, 1957 [Nov. 5, 1956], No. 34537/57. Drawings to Specification. Class 140. A leather replacement sheet material comprises a compressed layer which may be from 10 to 70 mls. thick, having a network of interconnecting pores and comprising non-woven matted fibres bound together by an initially thermoplastic extensible polymeric binder, coated on at least one surface with an extensible abrasion resistant polymeric material having perforations therein connecting with the pores of the compressed layer, the sheet material exhibiting water vapour permeability, scuff resistance, and flexibility. The polymeric binder may be plasticized and may be an elastomer (long list given) selected such that the softening point of the binder is at least 50 ‹ F. below that of the fibres. The fibres may be about 1.5 inches in length and about 3 denier. The polymeric binder-fibre weight ratio may be within the range 30 : 70 to 70 : 30. The same or substantially the same material may be used for the binder and the polymeric material of the coating. The coating may have a thickness of between 1 and 20 mls. and may have between 300 and 30,000 perforations per square inch. The perforations may be effected by needle punching using needles of between 1 and 10 ml. diameter. The hot pressing may be effected under a pressure of 50 to 1500 pounds per square inch and at a temperature above the softening point of the binder but below the softening point of the fibres. The network of pores may be formed (i) by stretching the sheet material from 10 to 50% in at least one direction thereby causing the fibres to break away from the binder as described in Specification 736,604, [Group IV (b)]; (ii) by soaking the sheet material in a liquid at a temperature sufficient to swell the fibres and deform the binder and shrinking the fibres by cooling; or (iii) by making the base of fibres of which 40 to 70% by volume are soluble (list given) and treating the sheet material with a solvent therefor. Lists of coating and fibre materials are given. Specifications 461,236, 535,262, 542,414, 553,733, [all in Group IV], 711,279, 711,280, 796,041, [all in Group IV (a)], and 811,444 also are referred to. |
