| 摘要 |
1,237,052. Low moisture spun polyester yarn. IMPERIAL CHEMICAL INDUSTRIES Ltd. 24 Feb., 1970 [28 March, 1969], No. 16457/69. Heading B5B. Filaments of aromatic polyester are made by melt extrusion, metered application of processing aids dissolved or dispersed in water, collection of filaments in a package, and drawing, characterized in that the initial concentration of water in such package is less than the concentration of water within a single such filament in equilibrium with an atmosphere of 100% selective humidity. In addition the initial concentration of water in a package of filaments produced as above may be within plus or minus 25% of the concentration of water in such a filament in equilibrium with the ambient atmosphere. In an example, 30 filaments of polyethylene terephthalate with an intrinsic viscosity of 0À67 measured in orthochlorophenol at 25‹ C. are extruded at 290‹ C. and wound up as 9À5 lb. bobbins of 537 denier zero twist yarn at 3226 feet per minute. The ambient atmosphere fluctuated between 50% and 65% relative humidity. A spin finish consisting of (A) 70% of the stearic acid ester of a hexadecyl alcohol; (B) 15% of the reaction product of 1 mole of cetyl/oleyl alcohol and 2À5 moles of ethylene oxide, and 12À5% of the reaction product of 1 mole cetyl/stearyl alcohol and 17 moles of ethylene oxide; (C) 2% dicresylol propane; and 0À5% stearic acid is applied to the filaments after extrusion and before wind up as a 14% by weight dispersion in water at a rate such that 0À4% by weight of total active finish ingredients are applied to the filaments. The theoretical application of water was therefore 2À46%, but due to rapid evaporation from the high speed threadline before winding, the moisture content of a freshly collected bobbin was 0À35% which would be in equilibrium with an atmospheric humidity of 30%. The spun yarn is drawn by leading it at a tension of 50 grams to a heated feed roll, passing it four times round this roll and a closely spaced skew idler roll and thence to a cold draw roll rotated at a surface speed 3À6 times that of the feed roll. From the draw roll the filaments are collected as a 150 denier yarn. The feed roll temperature is adjusted to an optimum value of 95‹ C. at which the draw tension variability is only 12 grams. |
