New leather substitute

摘要

A leather substitute comprises (a) a microporous block polyurethane film 0.1-1 mm. thick, adherent on one face, directly or indirectly, to (b) a shrunk, knitted textile layer made from a yarn containing both shrinkable fibres and fibres of shrinkage at least 5% less than that of the shrinkable fibres, impregnated with an elastomer of low modulus of elasticity. The shrinkable fibres make up 20-80% by weight of the knitted layer and have a shrinkage greater than 20%. The less shrinkable fibres have a shrinkage less than 10%. The shrinkable fibres may be of polyvinyl chloride, polyethylene terephthalate or isotactic polypropylene, and the less shrinkable fibres may be of a polyamide, polyacrylonitrile, or polyvinyl alcohol. The elastomer with which the knitted layer is impregnated is preferably the same block polyurethane as that of which the film is made, and the layer is impregnated with 20-60% of its weight of elastomer. In examples: (1) the knitted layer is raised and cropped and immersed in a solution of the block polyurethane which is precipitated out and the layer dried; the raised faces are then sprayed with a solution of polyurethane elastomer and the film placed on the sprayed face; the film is prepared by coating by a doctor a cotton fabric with a layer of powdered polyurethane, passing through an oven and between two heated rollers, the polyurethane layer being subsequently stripped from the fabric: (2) Example 1 is followed except that the film is formed of a woven textile layer of polyamide-viscose fibre yarn and the combination of film and woven textile layer is laminated to the shrunk knitted layer: (3) the knitted layer is raised and cropped and a fabric of polyamide and rayon fibre is stuck to the cropped face: the combination is impregnated with a solution of polyurethane and excess liquid removed between rollers: the impregnated combination is curtain coated with a stronger solution of polyurethane, the polyurethane precipitated and the combination dried.