GB869636A - Improvements in the production of bulked yarns and fabrics containing them - Google Patents

Abstract

869,636. Spinning composite yarns. DELAWARE MILLS Inc. Oct. 22, 1957, No. 32997/57. Class 120(3) High-bulk synthetic yarn is produced from tows of chemically similar continuous artificial filaments of the type which may be rendered " dimensionally unstable" by stretching and which may be relaxed to a relatively stable state with accompanying longitudinal shrinkage by subsequent application of heat e.g. polyacrylonitrile (having an acrylontrile content of at least 80% by weight) or polyethylene terephthalate filaments. Staple fibres formed from one such tow which are stable are blended with at least 30% (of the combined weights) of unstable staple fibres formed from another such tow to form a single sliver which is spun into yarn and the yarn is heated, prior or subsequent to its incorporation in a fabric, to a temperature and for a time such that the unstable fibres shrink longitudinally. The blended yarn may also comprise strength-conferring filaments of different composition from the main constituents. As shown in Figs. 1 and 2, a tow 11, spread and flattened at 10, is stretched between pinch rolls 12 and 13 and heated by plates 14, stapled by apparatus comprising stretch rolls 15 and ribbed breaker rolls 16, 18, condensed and crimped at 19, and the resultant sliver is, continuously or in batches, subjected alternately to vacuum for two minute periods and the action of steam, at 240‹F. for a total of 16-20 minutes, to shrink the fibres. Sliver 22 and a sliver 23, which has been similarly processed but with the omission of the relaxing at 20, are combined into a sliver 24 and spun into yarn 26 which may be knitted by a machine 29 into a fabric 30. Yarn or fabric is heated e.g. by steaming and/or during dyeing, to shrink the unstable fibre content and develop bulk. In a modified sliver preparation, Fig. 3, a tow 32, stretched and heated at 34 to produce unrelaxed fibres therein, is combined with a sliver 33 of relaxed fibres to form a sliver 36 which is consolidated and conveyed by aprons 37, 38, rolled on itself and condensed by a conical roller or scroll 39, then passed by nip rolls 40 to a crimping box 41. Specification 787,157 is referred to.