Cationic dyeable polyester composition, method for producing the same, and its uses

Abstract

The present invention discloses a cationic dyeable polyester composition and a method for producing the same, which is composed mainly of aromatic dicarboxylic acid units and ethylene glycol units. During the reaction of the polyester composition, a sulfonate compound, an ethylene glycol ester solution, and an alkali metal compound are added, and the ester solution has an esterification reaction rate of 95% or more. The polyester composition has a low content of insoluble compounds, little impurities, good spinnability, little increase in filtration pressure during spinning, and a long filter replacement cycle, resulting in low manufacturing costs.

Description

[Technical Field]

[0001] This invention relates to a cationic dyeable polyester composition, a method for producing the same, and its applications. Specifically, it relates to a cationic dyeable polyester composition with low content of insoluble compounds and diethylene glycol, and with a small increase in filtration pressure during spinning. [Background technology]

[0002] Polyester resins possess excellent mechanical and chemical properties, making them widely used in various industrial fields such as clothing and industrial fibers, magnetic tapes and thin films for surface coatings, and tire cords and LAN cables.

[0003] When used as a clothing fiber, isophthalic acid components containing sulfonic acid bases, such as sodium isophthalic acid-5-sulfonate, are used as copolymer components to produce modified cationic dyeable polyesters in order to improve the dyeability of polyester. Alternatively, isophthalic acid components containing sulfonic acid bases are used in combination with polyethylene glycol or the like to perform the modification. However, because sulfonic acid bases tend to cause physical crosslinking in polyester, the melt viscosity of the polyester increases significantly when the intrinsic viscosity (IV) is not high, resulting in a decrease in the strength of the final yarn, thus limiting its use in fields requiring high strength.

[0004] Furthermore, when melt spinning was performed using copolymer polyester obtained by modifying isophthalic acid components containing sulfonic acid bases, the filter pressure increased rapidly, making stable production difficult.

[0005] To improve the thickening phenomenon and filter pressure problems caused by sulfonic acid bases, Japanese Patent Publication No. 5-25708 discloses a modified polyester fiber. In this patent, polyester is modified with a terminal-sealed cation dyeable component, a polyether, and a diol component. In the resulting modified polyester, the cation dyeable groups are connected to the ends of the molecular chains, and there are no interacting physical crosslinking groups in the middle of the molecular chains. This significantly reduces the viscosity of the polyester, and the strength of the resulting cation polyester fiber is significantly improved compared to conventional polyesters modified with isophthalic acid components containing sulfonic acid bases. However, this patent has the problem that the terminal-sealed cation component used has a carboxylic acid group, and direct addition results in a high DEG (Diametric Index). [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a polyester composition having excellent cationic dyeability and high strength, and a method for producing the same, by suppressing the amount of insoluble compounds in the polymer. This suppresses the increase in filter pressure during polyester spinning. [Means for solving the problem]

[0007] The technical solution of the present invention is as follows: The cationic dyeable polyester composition is mainly composed of aromatic dicarboxylic acid units and aliphatic diol units. The polyester composition contains a sulfonic acid base represented by formula 1, and the content of the sulfonic acid base represented by formula 1 is 1000 to 5000 ppm, preferably 1000 to 3500 ppm, relative to the total amount of the polyester composition in terms of sulfur elements. The content of the compound represented by formula 2 is 10.0 mol% or less, preferably 5.0 mol% or less, relative to the total amount of the sulfonic acid base represented by formula 1, relative to the total amount of sulfur elements. The content of diethylene glycol is 0.8 to 5.0 wt% relative to the total amount of the polyester composition.

[0008] [ka]

[0009] In formulas 1 and 2, Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms, and Z and M are Li + kaNa + or K + That is the case.

[0010] The method for producing the cationic dyeable polyester composition of the present invention involves first preparing a low molecular weight polymer by esterifying or transesterifying an aromatic dicarboxylic acid or its ester-forming derivative with an aliphatic diol, and then polymerizing the low molecular weight polymer to obtain a polyester composition. At any stage before the polyester composition is obtained, an ester solution of a sulfonate represented by formula 3 and ethylene glycol, and an alkali metal compound are added. The esterification reaction rate of the ester solution is 95% or higher.

[0011] [ka]

[0012] In formula 3, Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms, and Z is Li + kaNa + or K + That is the case.

[0013] The amount of ester solution added is preferably 1,000 to 3,500 ppm relative to the total amount of the polyester composition in terms of sulfur elements. The alkali metal compound is preferably at least one selected from lithium acetate, potassium hydroxide, or sodium hydroxide. The amount of alkali metal compound added is preferably 10 to 1000 ppm relative to the total amount of the polyester composition in terms of alkali metal elements.

[0014] It is preferable to add the ester solution of sulfonate salt and ethylene glycol represented by formula 3 after the polymerization reaction. The polymer described in the present invention has excellent cationic dyeability and strength, and contains a small amount of diethylene glycol and insoluble compounds, so it can suppress the increase in filtration pressure during spinning.

Embodiments for Carrying out the Invention

[0015] In the prior art, generally, a cationic dyeable component having a sulfonate group such as an isophthalic acid-5-sulfonic acid metal salt is copolymerized with polyester to impart cationic dyeing performance to the polyester. However, since the sulfonate group is distributed in the middle of the polyester molecular chain, physical cross-linking is likely to occur in the polyester, increasing the viscosity of the polyester and decreasing its strength. Also, the hydrolysis resistance of the polyester deteriorates.

[0016] In order to solve the above problems, in the present invention, the sulfonate compound represented by Formula 3 is used as the cationic dyeable component.

[0017]

Chemical formula

[0018] In Formula 3, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group or an alkylphenyl group, and Z is Li + , Na + or K + . The sulfonate compound represented by Formula 3 contains only one carboxy group reactive group. In the polyester, the sulfonate compound is mainly connected to the molecular chain ends, and there are no physical cross-linking groups acting on each other in the middle of the molecular chain, so it can be ensured that the obtained polyester composition has a high molecular weight and excellent strength.

[0019] Examples of sulfonate compounds represented by Formula 3 include sodium 2-sulfobenzoate, potassium 2-sulfobenzoate, sodium 3-sulfobenzoate, lithium 3-sulfobenzoate, sodium 4-sulfobenzoate, sodium 2-sulfonate methyl benzoate, sodium 3-sulfonate methyl benzoate, sodium 4-sulfonate methyl benzoate, sodium 2-sulfonate ethyl benzoate, potassium 2-sulfonate ethylene glycol benzoate, sodium 3-sulfonate ethyl benzoate, sodium 4-sulfonate ethylene glycol benzoate, and lithium 3-sulfonate ethylene glycol benzoate, with sodium 3-sulfobenzoate being particularly preferred.

[0020] In a polyester composition to which a sulfonate compound represented by formula 3 is added as a cationic dyeable component, the sulfonic acid base represented by formula 1 is contained.

[0021] [ka]

[0022] In Formula 1, Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms, and Z is Li + kaNa + or K + That is the case.

[0023] In the polyester composition, the content of the sulfonic acid base represented by Formula 1 is 1,000 to 5,000 ppm relative to the polyester composition in terms of sulfur elements. If the sulfonic acid base represented by Formula 1 is less than 1,000 ppm relative to the polyester composition, the resulting product will have poor color development after dyeing. If the sulfur elements derived from the sulfonic acid base represented by Formula 1 are more than 5,000 ppm relative to the polyester composition, the extension of the polyester molecular chains will be suppressed, the polymerization will terminate without reaching the target viscosity, and a polyester composition with good physical properties will not be obtained. Considering the dyeability and the physical properties of the polyester composition as a whole, it is preferable that the content of the sulfonic acid base represented by Formula 1 is 1,000 to 3,500 ppm relative to the polyester composition in terms of sulfur elements.

[0024] The use of the monocarboxyl group sulfonate compound represented by Formula 3 improves the molecular weight and strength of the polyester composition, but it tends to increase the diethylene glycol content, which worsens the heat resistance of the polyester composition. In order to suppress the increase in diethylene glycol, an alkaline compound is added to the polyester composition in the present invention. Examples of the alkali metal compound include potassium hydroxide, sodium hydroxide, magnesium hydroxide, lithium hydroxide, magnesium acetate, potassium acetate, lithium acetate, potassium carbonate, calcium carbonate, magnesium carbonate, and sodium hexametaphosphate, with lithium acetate, potassium hydroxide, and sodium hydroxide being particularly preferred. The alkali metal compound may be added individually or in combination.

[0025] In the polyester composition described in the present invention, if the diethylene glycol content exceeds 5.0 wt%, the heat resistance of the polyester composition deteriorates, the conformability of the polyester composition deteriorates, and the creep-irreversible portion of the fiber increases. If the diethylene glycol content is lower than 0.8 wt%, the structure of the polyester composition becomes denser, affecting the bonding between the dye and the dyeable portion, and further affecting the uniformity and stability of the dyeing.

[0026] Therefore, in the polyester composition according to the present invention, in order to ensure that the diethylene glycol content is within an appropriate range, the amount of alkali metal compound added is preferably 10 to 1000 ppm relative to the total amount of the polyester composition in terms of alkali metal elements. If the amount of alkali metal compound added is too high, the color tone of the polyester composition will be inferior due to the excess alkali metal compound. If the amount of metal alkali compound added is too low, the effect of suppressing the formation of diethylene glycol will be small.

[0027] However, the alkali metal compound reacts with the sulfonate compound shown in formula 3 to produce the compound shown in formula 2.

[0028] [ka]

[0029] In Equation 2, M and Z are Li + kaNa + or K + Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms.

[0030] Since the compound represented by Formula 2 does not dissolve in the polyester composition, it becomes a foreign substance during the melt spinning stage, increasing the filter pressure during melt spinning, shortening the filter replacement cycle in the spinning process, and increasing spinning costs. For this reason, the sulfonate compound represented by Formula 3 is added as an ester solution with glycol so that the polyester composition can achieve good spinability and reduce spinning costs. Furthermore, by increasing the reaction rate, the amount of terminal carboxyl groups is reduced, thereby reducing the reaction rate between the alkali metal compound and the sulfonate compound represented by Formula 3. The content of the compound represented by Formula 2 in the polyester composition is preferably 10.0 mol% or less, and more preferably 5.0 mol% or less, relative to the total amount of sulfonic acid bases represented by Formula 1, in terms of sulfur elements.

[0031] Specifically, the esterified product of the sulfonate compound shown in formula 3 and the glycol is shown in formula 4.

[0032] [ka]

[0033] In formula 4, Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms, and Z is Li + kaNa + or K + That is the case.

[0034] The amount of ester solution added is 1,000 to 5,000 ppm relative to the total amount of polyester composition in terms of sulfur elements in the ester solution. If the amount of ester solution added is less than 1,000 ppm, the resulting color development after dyeing will be poor. If the amount of ester solution added is more than 5,000 ppm, the extension of polyester molecular chains will be suppressed, resulting in a polymerization plateau phenomenon, and the molecular weight of the resulting polyester composition will be small, resulting in poor physical properties. Considering the dyeability and the physical properties of the polyester composition as a whole, it is preferable that the amount of ester solution added is 1,000 to 3,500 ppm relative to the total amount of polyester composition in terms of sulfur elements in the ester solution.

[0035] A method for producing the cationic dyeable polyester composition described in the present invention involves first preparing a low molecular weight polymer by esterification or transesterification of an aromatic dicarboxylic acid or its ester-forming derivative with a glycol, and then polymerizing the low molecular weight polymer to obtain a polyester composition. At an optional stage before obtaining the polyester composition, an ester solution of a sulfonate compound represented by formula 3 and a glycol, and an alkali metal compound are added. The esterification reaction rate of the ester solution is 95% or higher.

[0036] [ka]

[0037] In formula 3, Y is an alkyl group, phenyl group, or alkylphenyl group having 2 to 20 carbon atoms, and Z is Li +kaNa + or K + That is the case.

[0038] The esterification reaction rate of the ester solution is 95% or higher. If the esterification reaction rate of the ester solution is lower than 95%, a large amount of the compound shown in Equation 2 will be produced, increasing the filter pressure during melt spinning, shortening the filter replacement cycle during the spinning process, and significantly increasing costs.

[0039] The ester solution of the sulfonate compound represented by Formula 3 and glycol can be added at any stage before obtaining the polyester composition, for example, during the esterification reaction or transesterification reaction, or during the polymerization reaction. To obtain a higher degree of polymerization and suppress the formation of easily elutable sulfonate low molecular weight polymers, it is preferable to add the ester solution of the sulfonate compound represented by Formula 3 and glycol after the start of the polymerization reaction.

[0040] Examples of aromatic dicarboxylic acids or their ester-forming derivatives described in the present invention include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate, dimethyl naphthalenedicarboxylic acid, and dimethyl phthalate, with terephthalic acid or dimethyl terephthalate being particularly preferred.

[0041] The esterification reaction is carried out in an esterification reactor where a low molecular weight polymer is already present, by continuously adding a slurry of glycol and aromatic dicarboxylic acid in a molar ratio of 1.05 to 1.50, or by adding all of the glycol and aromatic dicarboxylic acid before starting the esterification reaction in an esterification reactor where a low molecular weight polymer is already present.

[0042] The transesterification reaction is controlled to an appropriate rate by adjusting the molar ratio of glycol to aromatic dicarboxylic acid ester-forming derivative within the range of 1.50 to 2.50.

[0043] The catalyst for the transesterification reaction may be a variety of known catalysts, such as metal oxides or acetates thereof, including cobalt, magnesium, manganese, and titanium, and may be used in combination or individually.

[0044] The polymerization catalyst used in the method for producing the aforementioned cationic dyeable polyester composition may be any of the following known polymerization activators: antimony compounds, germanium compounds, titanium compounds, etc. These catalysts may be used in combination or individually.

[0045] In the polyester composition described in the present invention, in addition to aromatic dicarboxylic acids, aliphatic diols, and sulfonic acid groups represented by formula 1, other copolymerizing substances, such as polyethers or aliphatic dicarboxylic acids, may be added. Since the compound represented by formula 2 has some solubility in polyethers or aliphatic dicarboxylic acids, copolymerizing the polyester composition with a polyether or aliphatic dicarboxylic acid can reduce the amount of the compound represented by formula 2 precipitated in the polyester composition and further improve the polymerization filter pressure. Furthermore, by adding a polyether or aliphatic dicarboxylic acid, the polyester composition can be given low-temperature dyeing performance. Examples of the polyether include polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Examples of the aliphatic dicarboxylic acid include cyclohexanedicarboxylic acid, isophthalic acid, succinic acid, adipic acid, and glutaric acid. Of these, polyethylene glycol or cyclohexanedicarboxylic acid is preferred. The molecular weight of the polyethylene glycol is preferably 600 to 6000 g / mol, and more preferably 600 to 3000 g / mol. The amount of polyether or aliphatic dicarboxylic acid added to the total amount of the polyester composition is preferably 0.5 to 10.0 wt%, and more preferably 0.5 to 5.0 wt%.

[0046] The esterification and polymerization reactions for producing the cationic dyeable polyester composition of the present invention can be carried out using various conventional reaction apparatuses.

[0047] To further improve the heat resistance and strength of the cationic dyeable polyester composition of the present invention, it is preferable to perform solid-phase polymerization after the polymerization reaction is completed in the manufacturing process of the cationic dyeable polyester composition.

[0048] Specifically, the polyester product obtained by polymerization is pre-treated with crystallization, and then solid-phase polymerization is carried out at a reaction temperature of 200-240°C, a reaction pressure of 1000 Pa or less, and a reaction time of 100 hours or less to obtain the final polyester composition.

[0049] The cationic dyeable polyester composition of the present invention has good physical properties and excellent dyeability and dye stability. Furthermore, by controlling the amount of terminal carboxyl groups in the cationic dyeable component ester solution, the content of insoluble foreign matter in the polyester composition is reduced, resulting in less foreign matter during polyester melt spinning, less increase in filter pressure during the spinning process, longer filter replacement cycles, and lower costs.

[0050] The measurement and evaluation methods for each indicator of the present invention are as follows. (1) Intrinsic viscosity (IV) A 0.8 g section of the polyester composition is dissolved in 10 ml of o-chlorophenol solution, and the viscosity is measured using an Ubberohde viscometer under water bath temperature conditions of 25 ± 0.2 °C.

[0051] (2) Sulfur element content in insoluble compounds Take 2 g of the sample, dissolve it in 30 ml of hexafluoroisopropanol, filter the solution using 4 μm PTFE filter paper, and quantitatively analyze the sulfur element content on the filter paper by combustion.

[0052] (3) Analysis of sulfur element content in polyester compositions A quantitative analysis of the sulfur element content in polymers is performed using an FLX elemental analyzer.

[0053] (4) Evaluation of staining stability A polyester composition is spun to obtain drawn yarn, and the resulting drawn fibers are joined in pairs to create stockings under 22-needle spacing conditions. These stockings are then dyed for 60 minutes in a 130°C hot water bath with dye (Blue.TR) 3% owf, 0.5 ml / L acetic acid, 0.2 g / L sodium acetate, and a bath ratio of 1:100. After the dyed samples have accumulated and become opaque, they are measured using a spectrophotometer (Datacolor 650 manufactured by Datacolor Asia Pacific (HK) Ltd.) under CEI standard light source D65, 10 o Colorimetric measurement is performed under angular conditions to obtain L*.

[0054] (5) Calculation of the reaction rate of the ester solution (test of carboxyl group content) Take 0.5 g of the sample, dissolve it in 10 ml of o-cresol, and measure the amount of carboxyl groups using a potentiometric titrator with 0.2 mol / l sodium hydroxide.

[0055] (6) Diethylene glycol test For diethylene glycol in isophthalic acid diglycol sulfonate solution, 0.5 g of sample is taken, placed in 10 ml of hexanedioic acid, and the diethylene glycol content is measured by LC and internal standard method. For diethylene glycol in polyester, 0.5g of sample is taken, dissolved by heating with ethanolamine, 10ml of hexanediic acid is added, and the diethylene glycol content is measured by LC and internal standard method.

[0056] (7) Method for evaluating heat resistance An 8g section was placed in a test tube and heated under nitrogen gas at 300°C for 3 hours. The carboxyl group content of the section before and after heat treatment was then tested. A larger ΔCOOH (COOH before heat treatment - COOH after heat treatment) value indicates that the heat resistance of the polyester is poor.

[0057] (8) Increase in filter pressure ΔPa The test is performed using a small filterability tester for filter pressure testing. Under specific discharge rate conditions, cationic dyeable polyester is passed through a filter mesh with a mesh pore size of 5 μm, a test temperature of the polyester's melting point + 25°C, and a discharge rate of 10 g / min. At 30 minutes after the start of feeding, the pressure before filtration is defined as the initial pressure Pa1, and one hour later, the final pressure Pa2 is recorded. The increase in filter pressure over one hour is given by ΔPa = Pa2 - Pa1. A smaller ΔPa indicates less impurities in the polyester and more stable spinning.

[0058] (9) Toughness of the fibers Strength and elongation are calculated according to the standards of JIS L1013:2010 (Experimental methods for long fibers in chemical fibers) 8.8.1. Strength and elongation are measured using an ORIENTEC Co., RTC-1225A strength and elongation tester, and toughness = strength × (elongation). 0.5 This is the result. [Examples]

[0059] The advantages of the present invention will be explained in detail below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[0060] Example 1 Terephthalic acid (PTA) and glycol (EG) were homogeneously mixed and placed in a reaction vessel, where an esterification reaction was carried out at 240-260°C. After the esterification reaction was completed, the reaction product was transferred to a condensation vessel, an ester solution with a 99% esterification rate was added, followed by lithium acetate solution. Then, antimony trioxide as a catalyst and triethyl phosphate as a heat stabilizer were added, and a polymerization reaction was carried out at 260-290°C. After the polymer reached the required viscosity, it was discharged and cut to obtain the polyester composition. The intrinsic viscosity IV of the polyester composition was 0.64 dl / g, the polyester filter pressure rise ΔPa was 0.20 MPa / h, and the DEG value was 2.5%. The aforementioned chips were melt-spun at 290°C to obtain cationic dyeable polyester yarn. The sulfur content in the fibers was 2450 ppm, and the sulfur content in the insoluble compound was 4.7 ppm, which accounted for 0.19% of the sulfur content in the polyester composition. When the fiber toughness was 24 and the blue dye concentration was 3.0% owf, the L value after dyeing was 25.

[0061] Example 2 Cationic dyeable polyester compositions were prepared by changing the type of aromatic dicarboxylic acid or its ester-forming derivative, while maintaining the same conditions as in Example 1. See Table 1 for specific physical properties.

[0062] Examples 3-6 A cationic dyeable polyester composition was prepared by changing the amount of sulfonate salt shown in Equation 3, while keeping all other conditions the same as in Example 1. See Table 1 for specific physical properties.

[0063] Example 7 A cationic dyeable polyester composition was produced by changing the reaction rate of the sulfonate ester solution shown in Equation 3, that is, by changing the terminal carboxyl group value of the sulfonate ester solution, while keeping all other conditions the same as in Example 1. See Table 1 for specific physical properties.

[0064] Examples 8-12 A cationic dyeable polyester composition was produced by changing the amount of lithium acetate, an alkali metal compound, added, while keeping all other conditions the same as in Example 1. Refer to Tables 1 and 2 for specific physical properties.

[0065] Examples 13-14 A cationic dyeable polyester composition was produced by changing the type of alkali metal compound, while keeping all other conditions the same as in Example 1. See Table 2 for specific physical properties.

[0066] Examples 15-16 A cationic dyeable polyester composition was produced by changing the type of sulfonate shown in Equation 3, while keeping all other conditions the same as in Example 1. See Table 2 for specific physical properties.

[0067] Example 17 After the polymerization reaction was complete, solid-phase polymerization was carried out under conditions of a reaction temperature of 230°C, a reaction pressure of 50 Pa, and a reaction time of 80 hours or less, while other conditions were the same as in Example 1 to produce a cationic dyeable polyester composition. See Table 2 for specific physical properties.

[0068] Comparative Example 1 A cationic dyeable polyester was produced by directly adding sodium 3-carboxybenzenesulfonate, a sulfonate, under the same conditions as in Example 1. See Table 3 for specific physical properties.

[0069] In Comparative Example 1, because sodium 3-carboxybenzenesulfonate was added directly without esterification, the amount of the insoluble compound shown in Formula 2 in the polyester composition was too high. As a result, there was a large amount of impurities during the polyester melt filtration pressure test, the filtration pressure difference ΔPa was relatively large, and the spinning process became unstable.

[0070] Comparative Example 2 A cationically dyeable polyester was produced by directly adding a non-esterifying sodium 3-carboxybenzenesulfonate monomer, without adding an alkali metal compound, and under the same conditions as in Example 1. See Table 3 for specific physical properties. When sodium 3-carboxybenzenesulfonate monomer, which does not undergo esterification, is added directly, there are many terminal carboxyl groups, and the entire polymer system becomes acidic. Under conditions where no alkali metal compound DEG inhibitor is added, diethylene glycol is easily produced in excess. Diethylene glycol impairs the heat resistance of the polymer and makes polymerization plateauing more likely, resulting in a low final IV of the polyester.

[0071] Comparative Example 3 A sulfonate ester solution with a reaction rate of 99% was added, but without alkali metal compounds. Cationic dyeable polyester was produced under the same conditions as in Example 1. See Table 3 for specific physical properties. The ester solution had a reaction rate of 99%, and although it released few acidic ions, it contained a large amount of EG. As a result, without the addition of an alkali metal compound as a DEG inhibitor, it easily produced an excess of diethylene glycol. This diethylene glycol resulted in poor heat resistance of the polymer, and consequently, the physical properties of the final polyester were inferior.

[0072] Comparative Examples 4-6 A cationic dyeable polyester composition was produced by changing the reaction rate of the sulfonate ester solution, while keeping all other conditions the same as in Example 1. See Table 3 for specific physical properties. Although sodium 3-carboxybenzenesulfonate was esterified, the reaction rate was low, resulting in a large amount of terminal carboxyl groups. This led to an excessive amount of the insoluble compound represented by formula 2 in the polyester composition, resulting in a large amount of impurities during the final polyester melt filtration pressure test, a large increase in filtration pressure ΔPa, and unstable spinning.

[0073] Comparative Examples 7-8 A cationic dyeable polyester composition was prepared by changing the amount of sulfonate salt shown in Equation 3, while keeping all other conditions the same as in Example 1. See Table 3 for specific physical properties. If the amount of sulfonate added is too low, the dyeability is poor, and it is not possible to dye to the desired color. If the amount of sulfonate added is too high, the molecular weight of the resulting polyester composition is low, resulting in poor physical properties and insufficient yarn strength.

[0074] [Table 1]

[0075] [Table 2]

[0076] Table 3

[0077] Table 4

Claims

1. A cationic dyeable polyester composition comprising mainly aromatic dicarboxylic acid units and aliphatic diol units, wherein the polyester composition contains a sulfonic acid base represented by formula 1, and the content of the sulfonic acid base represented by formula 1 is 1000 to 5000 ppm of the total amount of the polyester composition in terms of sulfur elements, the content of the compound represented by formula 2 is 10.0 mol% or less of the total amount of the sulfonic acid base represented by formula 1 in terms of sulfur elements, the content of diethylene glycol in the polyester composition is 0.8 to 5.0 wt% of the total amount of the polyester composition, and the polyester composition contains alkali metal ions derived from alkali metal compounds, and the content of the alkali metal ions is 2 to 2000 ppm of the total amount of the polyester composition. 【Chemistry 1】 (In formulas 1 and 2, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group, or an alkylphenyl group, and Z and M are Li ＋ kaNa ＋ or K ＋ (That is the case.)

2. The cationic dyeable polyester composition according to claim 1, characterized in that the content of the sulfonic acid base represented by Formula 1 is 1,000 to 3,500 ppm in terms of sulfur elements relative to the total amount of the polyester composition.

3. The cationic dyeable polyester composition according to claim 1 or 2, characterized in that the content of the compound represented by formula 2 is 5.0 mol% or less in terms of sulfur element relative to the total amount of sulfonic acid base represented by formula 1.

4. A method for producing a cationic dyeable polyester composition according to claim 1, characterized in that a low molecular weight polymer is first produced by esterifying or transesterifying an aromatic dicarboxylic acid or its ester-forming derivative with an aliphatic diol, the low molecular weight polymer is polymerized to produce a polyester composition, and at any stage before the polyester composition is obtained, an ester solution of a sulfonate represented by formula 3 and ethylene glycol and an alkali metal compound are added, wherein the esterification reaction rate of the ester solution is 95% or more. 【Chemistry 2】 (In formula 3, Y is an alkyl group having 2 to 20 carbon atoms, a phenyl group, or an alkylphenyl group, and Z is Li ＋ kaNa ＋ or K ＋ (That is the case.)

5. The method for producing a cationic dyeable polyester composition according to claim 4, characterized in that the amount of ester solution added is 1,000 to 3,500 ppm relative to the total amount of the polyester composition in terms of sulfur elements.

6. A method for producing a cationic dyeable polyester composition according to claim 4 or 5, characterized in that the alkali metal compound is at least one selected from lithium acetate, potassium hydroxide, or sodium hydroxide.

7. A method for producing a cationic dyeable polyester composition according to claim 4 or 5, characterized in that the amount of alkali metal compound added is 10 to 1000 ppm relative to the total amount of the polyester composition in terms of alkali metal ion content.

8. A method for producing a cationic dyeable polyester composition according to claim 4 or 5, characterized in that the ester solution of the sulfonate represented by formula 3 and ethylene glycol is added after the polymerization reaction.

9. A fiber made using the cationic dyeable polyester composition described in claim 1.

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