Search

JP-7857115-B2 - Modified polyester composition and fibers and fiber structures thereof

JP7857115B2JP 7857115 B2JP7857115 B2JP 7857115B2JP-7857115-B2

Inventors

  • 阿部 周文
  • 梅田 雄太
  • 米田 泰之

Assignees

  • 株式会社ベルポリエステルプロダクツ
  • 大和製罐株式会社
  • 帝人フロンティア株式会社

Dates

Publication Date
20260512
Application Date
20220301

Claims (7)

  1. A copolymer polyester in which the main repeating unit is alkylene terephthalate and which contains 1.0 to 2.5 mol% of metal sulfonate group-containing isophthalic acid in the total dicarboxylic acid component, and which contains 0.7 to 3.0 % by mass of an organic ionic compound represented by the following general formula (I) based on the total mass of the copolymer polyester, The modified polyester composition contains 500 to 1000 ppm of benzoic acid and/or a benzoic acid derivative based on the total mass . A modified polyester composition characterized by having a chip color L value of 40 or more and a b value of 15 or less, as calculated using a colorimeter . RSO 3 X (I) (In formula (I) above, R represents an alkyl group having 1 to 30 carbon atoms or an aryl group having 7 to 40 carbon atoms, and X represents a cation containing one or more alkali metals, alkaline earth metals, quaternary ammonium salts, or quaternary phosphonium salts.)
  2. The modified polyester composition according to claim 1, characterized in that it contains an organic salt compound in which X is a tetraalkylphosphonium ion in the above formula (I).
  3. The modified polyester composition according to claim 1 or claim 2, wherein the intrinsic viscosity of the modified polyester composition is in the range of 0.50 to 1.30 dl/g.
  4. A modified polyester composition according to any one of claims 1 to 3, characterized in that the main repeating unit is ethylene terephthalate.
  5. A polyester fiber comprising the modified polyester composition described in any one of claims 1 to 4.
  6. The polyester fiber according to claim 5, wherein the fineness is 1.1 dtex or less.
  7. A polyester fiber structure comprising polyester fibers according to claim 5 or 6.

Description

This invention relates to a modified polyester composition dyeable with cationic dyes, fibers and fiber structures made thereof, and more specifically, to a modified polyester composition that enables the production of fibers with significantly improved physical properties such as strength. Polyester resins, such as polyethylene terephthalate (PET), possess many excellent properties and are therefore widely used as fibers and films. However, general-purpose polyesters such as PET are typically dyed with disperse dyes, which presents challenges in terms of color development and colorfastness. Therefore, a method for enabling dyeing with cationic dyes by copolymerizing an isophthalic acid component containing a sulfonic acid metal salt, such as 5-sodium sulfisoisophthalic acid, within the polyester main chain is known (e.g., Patent Document 1). However, the resin obtained by this method exhibits a significant increase in the melt viscosity of the polymer due to copolymerization of its components. Therefore, attempting to adjust it to the typical intrinsic viscosity of PET fibers increases the stirring load during the polycondensation process, severely degrading spinning operability in melt spinning, thus limiting its applications. To overcome the drawbacks of such cationic dye-dyeable polyesters, compositions have been proposed in which an isophthalic acid component having a phosphonium sulfonic acid salt with weak ionic intermolecular forces is copolymerized (Patent Documents 2 and 3). This method suppresses the thickening effect of the polymer, thereby improving the strength of the resulting fibers and the vividness when dyed with cationic dyes. However, the effects of this method are limited, and when considering general use as clothing fibers, neither the strength nor the vividness can be considered sufficient. On the other hand, there have also been proposals for compositions containing organic sulfonic acid metal salts that are non-reactive with the copolymerized polyester, such as alkylbenzene sulfonic acid metal salts (Patent Document 4). It has been shown that high-strength cationic dyeable polyesters can be obtained from such compositions. However, in compositions obtained by this method, the color tone deteriorates as the amount of organic sulfonic acid metal salt increases. Furthermore, the resulting fibers exhibit a trade-off between physical properties such as fiber strength and the ability to achieve deep dyeing and vivid color development when dyed with cationic dyes; it was not possible to satisfy both simultaneously. Japanese Patent Publication No. 2003-261754JP-A-1-162822Japanese Patent Publication No. 2006-36953Japanese Patent Application Publication No. 4-264126 This is a schematic diagram showing an example of a false twisting apparatus for implementing the method of the present invention. <Copolymerized polyester> In the modified polyester composition of the present invention, the main repeating unit is alkylene terephthalate, and it is particularly preferable that the alkylene terephthalate consists of at least one of the group consisting of ethylene terephthalate, trimethylene terephthalate, and butylene terephthalate, with ethylene terephthalate being the most preferred. As a copolymer, it is necessary that the metal sulfonate group-containing isophthalic acid component is copolymerized at a concentration of 1.0 to 5.0 mol% relative to the total dicarboxylic acid component. If the copolymerization amount is less than 1.0 mol%, the dye clarity after cationic dyeing of the fibers will be poor. On the other hand, if the copolymerization amount exceeds 5.0 mol%, the clarity with cationic dyes will be almost saturated, and the material will become more susceptible to hydrolysis, resulting in inferior physical properties such as strength. The metal component of the metal sulfonate group-containing isophthalic acid component is selected from alkali metals, with Na, K, and Li being preferred. <Organoionic compounds represented by formula (I)> The key is to provide a modified polyester composition containing 0.5 to 5.0% by mass of an organic ionic compound represented by the following general formula (I), based on the total mass of the copolymerized polyester. RSO 3 X (I) (In formula (I) above, R represents an alkyl group having 1 to 30 carbon atoms or an aryl group having 7 to 40 carbon atoms, and X represents a cation containing one or more alkali metals, alkaline earth metals, quaternary ammonium salts, or quaternary phosphonium salts.) In formula (I) above, when R is an alkyl group, the alkyl group may be linear or have branched side chains. In the above formula (I), X represents a cation consisting of one or more alkali metals such as Na, K, and Li, or alkaline earth metals such as Mg and Ca, or quaternary ammonium salts and quaternary phosphonium salts. Among alkali metals, Li, Na, and K are preferred. Such organic ionic compounds may be used individually or as a mixture of two or more.