Abstract: High-quality differential-shrinkage polyester combined filament yarn having good color tone and being free from fluffing can be made from a polyester polymer produced by using a catalyst comprising (I) a mixture consisting of a Ti compound component composed of one or more members selected from among titanium alkoxides of the general formula (I) and products of reaction of these alkoxides with carboxylic acids of the general formula (II) or anhydrides thereof and a P compound component consisting of a compound of the general formula (III) and/or (2) a product obtained by reacting a Ti compound component composed of one or more members selected from among titanium alkoxides of the general formula (I) and products of reaction of these alkoxides with carboxylic acids of the general formula (II) or anhydrides thereof with a P compound component consisting of a compound of the general formula (IV).

Abstract: Polyester fibers having a deformed section are produced from a polyester polymer which is obtained by polycondensing an aromatic dicarboxylate ester in the presence of a catalyst containing a mixture of a Ti component (A) comprising at least one a titanium alkoxide or a reaction product thereof with a specific carboxylic acid or its anhydride with a P compound component (B) represented by the following general formula (III) and/or a reaction product of a Ti compound component (C) with a P compound component (D) represented by the following general formula (IV). The obtained fibers have a favorable color tone and excellent qualities without showing fluffing.

Abstract: High-quality differential-shrinkage polyester combined filament yarn having good color tone and being free from fluffing can be made from a polyester polymer produced by using a catalyst comprising (I) a mixture consisting of a Ti compound component composed of one or more members selected from among titanium alkoxides of the general formula (I) and products of reaction of these alkoxides with carboxylic acids of the general formula (II) or anhydrides thereof and a P compound component consisting of a compound of the general formula (III) and/or (2) a product obtained by reacting a Ti compound component composed of one or more members selected from among titanium alkoxides of the general formula (I) and products of reaction of these alkoxides with carboxylic acids of the general formula (II) or anhydrides thereof with a P compound component consisting of a compound of the general formula (IV).

Abstract: Irregular cross-sectional filaments made from a polyester and yarns and fabrics comprising the filaments, the cross-sectional profile of which filaments has a triangular part (A) and a flat projection part (B) connected to an angular portion of the triangular part and extending therefrom in a flat form, and satisfies the requirements (1) and (2): 0.7≦(L1/L2)≦3.0  (1) and 3.0≦(h2/h1)≦10.

Abstract: A thick and thin polyester multifilament yarn having an excellent natural fiber yarn-like hand, a dry touch and spun yarn-like appearance includes a plurality of individual thick and thin polyester multifilaments varying in thickness along the longitudinal direction thereof and exhibits a spectrum having a first peak (Pmax1) of a coefficient of variation in yarn thickness of 4 to 10 cm, a second peak (Pmax2) of the yarn thickness variation coefficient of 50 to 150 cm and a ratio (Pmax1/Pmax2) of 1.5 to 4.0, measured by the normal mode test method using the Uster evenness tester.

Abstract: A thick and thin polyester multifilament yarn having an excellent natural fiber yarn-like hand, a dry touch and spun yarn-like appearance includes a plurality of individual thick and thin polyester multifilaments varying in thickness along the longitudinal direction thereof and exhibits a spectrum having a first peak (Pmax1) of a coefficient of variation in yarn thickness of 4 to 10 cm, a second peak (Pmax2) of the yarn thickness variation coefficient of 50 to 150 cm and a ratio (Pmax1/Pmax2) of 1.5 to 4.0, measured by the normal mode test method using the Uster evenness tester.

Abstract: Irregular cross-sectional polyester filaments (which may be thick and thin type filaments) containing a polyester and having a cross-sectional profile which has