Modifying a polyester with special chain-brancher residues in carefully controlled amounts to provide a draw-texturing feed yarn that can be draw-textured at a speed of 1,000 mpm without excessive filament breaks, and with other advantages in the resulting textured yarns, such as improved bulk and dyeability over prior polyester yarns that could not be satisfactorily textured under similar conditions.
CROSS-REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 07/402,005, filed Sept. 1, 1989, which is a continuation-in-part of application, Ser. No. 06/907,299, filed Sept. 12, 1986 abandoned.
A process for preparing highly oriented undrawn core-sheath type conjugated polyester fibers including the step of spinning a polyester as the sheath polymer and a polymer having a larger gradient of elongational viscosity with the temperature than that of the sheath polymer as a core polymer at a spinning speed of about 4000 to 12000 m/min.
A highly oriented undrawn polyester fiber which is crystalline such that the fiber is capable of exhibiting a diffraction peak observable in a wide angle X-ray diffraction image of the fiber and has a birefringence of 0.015 to 0.05. A process for preparing highly oriented undrawn core-sheath type conjugated polyester fibers including the step of spinning a polyester as the sheath polymer and a polymer having the larger gradient of elongational viscosity with the temperature than that of the sheath polymer at a spinning speed of about 4000 to 12000 m/min. A textured yarn made of said highly oriented undrawn polyester fibers and a process for preparing the textured yarn.
The present invention is a pre-oriented, undrawn polyester fiber spun with spooling speeds of at least 3,000 m/min., wherein the polyester is a copolymer comprised essentially of ethylene terephthalate units and up to 10 weight % of other dicarboxylic acids or other diols, and carboxy phosphonic acid units of the formula: ##STR1## wherein R is selected from C.sub.1-10 -alkylene, C.sub.1-10 -cycloalkylene or C.sub.6-10 -arylene, in a quantity corresponding to 30 to 500 ppm phosphorus, in relation to polyester. The invention also comprises a process for the production of this fiber.
Simultaneous drawing of mixed polyester filaments is improved by use of chain-branched polyester for the polymer from which the polyester filaments are spun.
The present invention is a pre-oriented, non-stretched polyester fiber spun with spooling speeds of at least 3,000 m/min., wherein the polyester is a copolymer comprised essentially of ethylene terephthalate units and up to 10 weight % of other dicarboxylic acids or other diols, and carboxy phosphonic acid units of the formula: ##STR1## wherein R is selected from C.sub.1-10 -alkylene, C.sub.1-10 -cycloalkylene or C.sub.6-10 -arylene, in a quantity corresponding to 30 to 500 ppm phosphorus, in relation to polyester. The invention also comprises a process for the production of this fiber.
