| 摘要 |
<p>1,261,337. Hot stretching and relaxing polyester yarns. CELANESE CORP. 2 April, 1970 [12 May, 1969], No. 15675/70. Heading B5B. Filamentary polyester yarn, wherein the polyester is composed of at least 85% by weight of a polymeric ester of a dihydric alcohol and terephthalic acid is hot stretched by at last 8% and then hot-relaxed at least 7%, based on the original length of the yarn at a temperature lower than any used in stretching it and between 325‹ F. and 400‹ F., the net change in length being not more than 2% of the original length. In accordance with these conditions the yarn may be stretched by from 8 to 16% and relaxed by from 7 to 14%. The yarn may be stretched at temperatures of from 390‹ to 490‹ F. The yarn may be passed through two or more heating zones at successively higher temperatures before relaxation, stretching being effected in at least one of the zones and the yarn being maintained under sufficient tension to prevent it from shrinking in the zone(s) wherein stretching is not being effected. A composition for securing adhesion of the yarn to rubber may be applied to the yarn and dried thereon before the yarn is hot stretched. The yarn may be composed of filaments consisting of polyethylene terephthalate having an intrinsic viscosity of between 0À7 and 1À5 decilitres/gram (as measured in o-chlorophenol at 25‹ C. The term " yarn " is defined as including mono-filaments and multi-filament bundles with or without twist, but excluding spun staple fibre yarn. By means of the invention yarns can be obtained which can be further processed at temperatures at least up to the relaxation temperature used with negligible, if any, decrease in strength, while yarns treated under standard conditions lose 12 to 15% of their strength at temperatures reached during rubber-curing operations.</p> |
