GB1140710A - Unbonded fibrous assembly - Google Patents

Abstract

1,140,710. Fabric laminates. E. I. DU PONT DE NEMOURS & CO. 30 May, 1967 [1 June, 1966(2)], No. 24799/67. Heading B5N. [Also in Divisions D1 and F4] An unbonded web comprises crimped staplelength orientated synthetic polymer fibres having at least a partial coating of an unorientated synthetic polymer having a melt temperature of at least 70‹ C. but less than the fibre stick temperature of the fibre polymer, e.g. within 5-50‹ C. of the latter. The fibres have an average length of at least one inch, a maximum retractive coefficient of not more than 30, a crimp frequency of at least 3 crimps per inch and an average crimp index of at least 3%. The web has a density of not more than 1 1b/cub. ft. The web is made by forming a tow of a filamentary polymer, crimping filaments in the tow, separating the crimped filaments, at least partially coating the filaments with the lower melting polymer, transversely cutting the tow to form sections of staple length fibres, e.g. 1-6", then opening and mechanically distributing the fibres to form the web, the method including, prior to the web forming step, annealing the filamentary polymer at an elevated temperature in a relaxed state so as to provide the maximum retractive coefficient of not more than 30. The lower melting polymer can be applied in fibre form or by spraying, e.g. as a solution or aq. dispersion or by dipping an opened tow in a solution of the polymer, squeezing and drying, e.g. at 120-160‹C. under a tension of not more than 0À009 (see Fig. 5, not shown). The lower melting polymer can be polyolefins, acrylic resins, acrylic terpolymers, polyesters, copolyesters, polyamides, copolyamides, vinyl polymers and copolymers. The filaments can have a denier of 1-50 denier per filament and is preferably formed from the same class of polymer as the low melting polymer. The filament tow can be drawn and may be annealed once or twice by air, water or steam at a temperature above 80‹ C. and deregistered into separate filament groups. The filaments may become crimped during annealing. In Ex. 14 trilobal filaments are used to form the web. The fibres can be formed into the web by carding, garnetting or cross-lapping. The fibres can be removed from the carding machine and collected on a perforated belt by an air stream so as to reform the web. The web can be bonded by heating to melt the lower m.p. polymer. During bonding an air stream can be forced through the web to minimize compaction. The web can be bonded whilst in a mould. The web can contain 0-95% uncoated or monocomponent filaments. The web can be converted into slivers, bonded yarns or knitted tufted and woven fabrics or formed into a bonded block of aligned fibres which can be sliced and bonded with the fibres end-on to woven cotton cloth with an ethylene terephthalate/ethylene azelate adhesive, see Examples 15-18. The Specification also discloses corresponding webs formed of non-annealed fibres.