| 摘要 |
Staple fibres and filaments of high density and high shrinkability are made by stretching filaments of an acrylonitrile polymer (a homopolymer or a copolymer containing not less than 70% by weight of units derived from acrylonitrile) by a factor of 1.5 to 2.5, at 135 DEG C. to 145 DEG C. for 0.25 to 2 seconds, the filaments before stretching having a length at most 1.5 times their as-spun length and containing at most 10% by weight of water and at most 3% of spinning solvent. A bulky yarn is made by subjecting a yarn comprising a mixture of staple fibres formed as above, and staple fibres of substantially lower shrinkability, to conditions which cause the acrylonitrile polymer fibres to shrink. In an example, a tow of high shrinkability acrylonitrile copolymer filaments produced as above is crimped at 21 DEG C. in a stuffer box, and then cut to staple simultaneously with 3 tows of lower shrinkability made of the same copolymer. The top contained 19% of the high shrinkability fibres, and was drafted with further staple fibres of the same copolymer to give a blend containing 10% high shrinkability fibres. This was processed into worsted yarn, steam relaxed at 135 DEG C. in saturated steam, and stretched 30% cuasing breakage or displacement of the fibres. Specification 586,926 is referred to.
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