| 摘要 |
1,228,640. Yarn consisting of composite polyester filaments. TORAY INDUSTRIES Inc. 10 Oct., 1968, No. 48174/68. Heading B5B. A yarn consisting of a number of composite filaments each of the conjugate type or the eccentric sheath core type and each consisting of two thermoplastic high polymer components is characterized in that each filament develops more than 16 crimps per cm. after treatment with coiling water, the apparent shrinkage of each crimped filament when treated with boiling water is in the range 30 to 65%, and the true shrinkage of each crimped filament when heated to 160‹ C. is less than 10À0%. The high polymers may be polyesters and they may differ from one another in intrinsic viscosity by more than 0À05. The contraction stress of each crimped filament when heated in a bath of a silicone maintained at 180‹ C. is less than 120 mg./denier. One of the two polyesters preferably has an intrinsic viscosity within the range 0À45 to 0À55 and the other within the range 0À60 to 0À85. The composite filaments may be produced by melt spinning the polyesters at a temperature of 290‹ to 300‹ C. in such a manner that the filaments formed are of either the eccentric sheath-core type or preferably of the conjugate side-by-side or "bimetal" type. The molten extruded composite filaments are cooled and solidified by means of a flow of cooled air and wound up to form a package at a tension higher than 0À15 g./denier the multifilament yarn thus obtained is drawn at a draw ratio of 3À0 to 3À8 using either a plate maintained at a temperature between room temperature and 180‹ C. a snubbing pin maintained at a temperature between the glass transition temperature of the polyester and 160 ‹ C. The drawn yarn is passed through a tube maintained at a temperature within the range 130‹ to 240‹ C., preferably 200 to 230‹ C. During its passage through the heated tube the yarn is allowed to relax 10 to 70%, preferably about 20%. This heat treatment causes the filaments of the yarn to develop helical crimps. The pairs of polyesters used in the examples are polyethylene terephthalates having intrinsic viscosities of 0À50 and 0À80 respectively and polyethylene terephthalate of intrinsic viscosity of 0À48 used in conjunction with polyparaoxyethylene benzoate having an intrinsic viscosity of 0À56. The intrinsic viscosities of the polyesters are determined at 25‹ C. using o-chlorophenol as the solvent. The number of crimps per cm. of the crimped filament is measured under a load of 1 mg./denier. The apparent per cent shrinkage is also measured under this load, the yarn having been immersed in water at 98‹ C. for 15 minutes under no tension. The apparent shrinkage is measured under a load of 200 mg./denier, the yarn having been subjected to dry heat at 160‹ C. under no tension. The contraction stress is measured with a strain meter using a crimped yarn loaded with a weight of 1/30 g./denier and immersed in a silicone oil bath at 180‹ C. |
