Dyeable composite elastic fiber and method of making same

Abstract

The present application relates to the technical field of elastic fiber, in particular to an easy-to-dye composite elastic fiber and a preparation method thereof. The composite elastic fiber is prepared by melt spinning of thermoplastic polyester chips and modified PBT chips. The thermoplastic polyester chips comprise the following raw materials in parts by weight: polytrimethylene terephthalate 65-80 parts, polyamide copolymer 10-25 parts, compatibilizer 2-8 parts, lubricant 0.5-3 parts, and antioxidant 0.1-1 part. The modified PBT chips have good mechanical properties, high heat resistance, easy dyeing and easy processing, by introducing 1,4-cyclohexane dimethanol and sulfonic acid groups into the PBT molecular chain. The easy-to-dye composite elastic fiber prepared by the compounding of modified PBT and thermoplastic polyester for spinning processing has the characteristics of high comprehensive mechanical properties, good heat resistance and excellent dyeing performance.

Description

Technical Field

[0001] This invention relates to the field of elastic fiber materials technology, specifically to an easily dyeable composite elastic fiber and its preparation method. Background Technology

[0002] Polyester fibers, represented by polyethylene terephthalate (PET), polypropylene terephthalate (PTT), and polybutyl terephthalate (PBT), are a class of spinning materials with excellent mechanical properties and high processability, and are widely used in various textile products. However, due to the differences in application fields and usage environments, polyester fibers have different performance requirements. The application of a single PET, PBT, or PTT fiber is inevitably limited by its material characteristics. For example, PBT has good overall performance but low notched impact strength, poor toughness, and is difficult to dye; PET, due to its tightly packed molecular structure and lack of hydrophilic groups, has poor moisture absorption, poor tensile recovery, and is flammable; PTT has excellent tensile resilience and stability, but poor water absorption and heat resistance.

[0003] Regarding fiber dyeing, PTT exhibits superior dyeing performance compared to PBT and PET. It typically employs disperse dyes for medium-to-high temperature dyeing. However, with the advancement of cationic dyeing technology, cationic dyeing offers advantages such as lower cost, greater variety, environmental friendliness, brighter colors, and higher colorfastness, better meeting the market's demand for diverse fiber products. Therefore, to further in-depth research and development of fiber products, it is necessary to broaden research into fiber dyeing processes. This invention aims to overcome the shortcomings of single polyester fibers to obtain a composite elastic fiber with strong comprehensive mechanical properties, good dyeing performance, and excellent processability, thereby meeting diverse market demands. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing an easily dyeable composite elastic fiber. The elastic fiber has good comprehensive mechanical properties, heat resistance, processing performance and dyeing performance. Furthermore, the preparation method of the composite elastic fiber is simple to operate, the product quality is stable and it is suitable for large-scale production.

[0005] The objective of this invention is achieved through the following technical solution: an easily dyeable composite elastic fiber, wherein the composite elastic fiber is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips, wherein the thermoplastic polyester chips comprise the following raw materials in parts by weight: 65-80 parts of polypropylene terephthalate, 10-25 parts of polyamide copolymer, 2-8 parts of compatibilizer, 0.5-3 parts of lubricant, and 0.1-1 parts of antioxidant.

[0006] Furthermore, the modified PBT chips have sulfonic acid groups randomly distributed on their molecular chains.

[0007] Furthermore, the preparation method of the modified PBT chips includes the following steps: (1) Terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, and the reaction is carried out at a temperature of 230-250℃ while stirring for 2-4 hours; (2) Sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to the reaction vessel, the reaction temperature is 230-250℃, the reaction pressure is 20-80Pa, the reaction time is 30-50min, pre-polymerization is carried out, and then the reaction temperature is increased to 240-260℃, the reaction pressure is 20-60Pa, the reaction time is 2-3h, and after the reaction is completed, the material is cooled and sliced ​​to obtain the modified PBT chips.

[0008] Further, in step (1), the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediol is 1:1.6-1.8, and the molar ratio of 1,4-cyclohexanediol to 1,4-butanediol is 1:2-2.5. The added mass of tetrabutyl titanate is 0.03% of the added mass of terephthalic acid.

[0009] Furthermore, in step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 5-20% of the theoretical product mass.

[0010] This invention employs the above-mentioned technical solution to introduce 1,4-cyclohexanediethanol and sulfonic acid groups into the PBT molecular chain, resulting in modified PBT chips with good mechanical properties, high heat resistance, easy dyeing, and easy processing. Specifically, by adding 1,4-cyclohexanediethanol in step (1), the crystallinity of the modified PBT is reduced, thereby preventing warping and deformation of the modified PBT chips during processing; and it also increases the melt viscosity, strength, and fluidity of the final modified PBT polyester, thereby improving the strength, processing performance, and heat resistance of the modified PBT chips. By adding sodium bis(hydroxyethyl) isophthalate-5-sulfonate in step (2), the appropriate introduction of sulfonic acid groups as active staining sites significantly improves the staining performance of the modified PBT chips.

[0011] Furthermore, the preparation method of the polyamide copolymer is as follows: m-phenylenediamine and modified diamine prepolymer are added to 90-110 mL of dimethylacetamide solvent and stirred to dissolve. After dissolution, the solution is transferred to a constant temperature refrigeration cycle bath at -5-0℃. Then, 17.5-19.2 g of isophthaloyl chloride is added dropwise, and the temperature is maintained at 15-25℃ while stirring for 1-2 h. 7-8 g of calcium hydroxide is added to obtain a viscous polymer. The viscous polymer is placed in deionized water to precipitate, washed with water, and then dried in an oven to obtain the polyamide copolymer.

[0012] Furthermore, the molar ratio of the modified diamine prepolymer to m-phenylenediamine is 1:8.5-9.2.

[0013] Furthermore, the preparation method of the modified diamine prepolymer is as follows: 2,4-diaminobenzenesulfonic acid and anhydrous calcium chloride are heated to 80-90℃ and dissolved in 30-40 mL of dimethylacetamide. Then, the mixture is transferred to a low-temperature circulating freeze bath at -5-0℃, and isophthaloyl chloride is slowly added and reacted for 20-25 min. The temperature is then increased to 10-15℃ and reacted for 0.5-1 h. Next, m-phenylenediamine is added, and the reaction temperature is increased to 20-25℃ and stirring is continued for 1-1.5 h. Finally, the resulting viscous polymer is placed in deionized water to precipitate, and after washing and drying, the modified diamine prepolymer is obtained. The molar ratio of 2,4-diaminobenzenesulfonic acid, anhydrous calcium chloride, isophthaloyl chloride, and m-phenylenediamine is 1:2:2:2.

[0014] Furthermore, the compatibilizer is at least one selected from hexadecylamine, phenyl phthalate, polyethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and maleic anhydride-grafted polyethylene copolymer.

[0015] Furthermore, the lubricant is at least one of liquid paraffin, organosilane, oleamide, and ethylene dicarboxylic acid amine.

[0016] Furthermore, the oxidant is at least one selected from alkyl phosphate, trimethyl phosphate, trimethyl phosphite, triphenyl phosphate, antioxidant 1010, and antioxidant 168.

[0017] Furthermore, the intrinsic viscosity of the poly(propylene terephthalate) is 0.8-1.2 dL / g.

[0018] This invention employs the above-mentioned technical solution, and the addition of polyamide copolymers effectively improves the strength, heat resistance, and stability of polypropylene terephthalate (PPT). The polyamide copolymer obtained through the above preparation method exhibits excellent mechanical properties and high thermal stability. More preferably, 2,4-diaminobenzenesulfonic acid is introduced as a third monomer into the copolymerization modification of the polyamide copolymer using a modified diamine prepolymer preparation method, serving as an active dyeing site to enhance the dyeing performance of the thermoplastic polyester chips. Simultaneously, the introduction of sulfonic acid groups generates hydrogen bonds between molecular chains, further contributing to improved mechanical properties of the thermoplastic polyester chips. This invention, using PBT and polyamide copolymers as main raw materials, along with compatibilizers, lubricants, and oxidants, produces thermoplastic polyester chips suitable for elastic fiber spinning. This overcomes the performance deficiencies of single PBT or thermoplastic polyester materials, resulting in a composite elastic fiber with excellent comprehensive mechanical properties and a wide range of applications.

[0019] The present invention also provides a method for preparing the above-mentioned easily dyeable composite elastic fiber, characterized by the following steps: placing thermoplastic polyester chips and modified PBT chips in vacuum drying ovens at 120-140℃ and 110-120℃ respectively for drying for 4-12 hours; then placing the dried thermoplastic polyester chips and modified PBT chips in a twin-screw melt spinning machine at a mass ratio of 30:70-70:30 for heating and melting, then distributing them through a spinneret and converging them at the outlet of the spinneret, and obtaining the composite elastic fiber by air cooling, side blowing cooling, stretching, oiling, and winding.

[0020] Specifically, the spinning heating temperature of the modified PBT chips is 265-285℃, the spinning heating temperature of the thermoplastic polyester chips is 255-265℃, the spinning speed is 2000-3000m / min, the ring blowing temperature is 30℃, the stretching ratio is 1.5-4 times, and the drawing temperature is 130-160℃.

[0021] The beneficial effects of this invention are as follows: The easily dyeable composite elastic fiber obtained by melt spinning thermoplastic polyester chips and modified PBT chips has the characteristics of high comprehensive mechanical properties, good heat resistance, and excellent dyeing performance. Specifically, by introducing 1,4-cyclohexanediethanol and sulfonic acid groups into the PBT molecular chain, modified PBT chips with good mechanical properties, high heat resistance, and easy dyeing and processing are obtained. The thermoplastic polyester chips prepared using polypropylene terephthalate and polyamide copolymer as the main raw materials retain the excellent elasticity and processing properties of polypropylene terephthalate while enhancing its strength, heat resistance, and dyeing performance. The composite elastic fiber described in this invention can be applied to civilian and industrial textiles in fields such as clothing, packaging, automobiles, medical and health care, and construction, and has broad market prospects and application potential. Detailed Implementation

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0023] Example 1

[0024] A dyeable composite elastic fiber, wherein the composite elastic fiber is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips, wherein the thermoplastic polyester chips comprise the following raw materials in parts by weight: 65 parts of polypropylene terephthalate, 10 parts of polyamide copolymer, 2 parts of compatibilizer, 0.5 parts of lubricant, and 0.1 parts of antioxidant.

[0025] In this embodiment, the preparation method of the modified PBT chips includes the following steps: (1) Terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, and the reaction is carried out at 230°C with stirring for 4 hours; (2) Sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to the reaction vessel, the reaction temperature is 230°C, the reaction pressure is controlled at about 60 Pa, the reaction time is 30 min, pre-polymerization is carried out, and then the reaction temperature is increased to 240°C, the reaction pressure is controlled at about 20 Pa, the reaction time is 2 h, and after the reaction is completed, the material is cooled and sliced ​​to obtain the modified PBT chips.

[0026] In step (1), the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediethanol is 1:1.6, the molar ratio of 1,4-cyclohexanediethanol to 1,4-butanediol is 1:2, and the added mass of tetrabutyl titanate is 0.03% of the added mass of terephthalic acid.

[0027] In step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 5% of the theoretical product mass.

[0028] In this embodiment, the intrinsic viscosity of the polypropylene terephthalate is 0.9 dL / g.

[0029] In this embodiment, the preparation method of the polyamide copolymer is as follows: m-phenylenediamine and modified diamine prepolymer with a molar ratio of 1:8.5 are added to 90 mL of dimethylacetamide solvent and stirred to dissolve. After dissolution, the solution is transferred to a constant temperature freezing cycle bath at -5°C. Then, 17.5 g of isophthaloyl chloride is added dropwise, and the temperature is maintained at about 15°C while stirring for 1 hour. 7 g of calcium hydroxide is added to obtain a viscous polymer. The viscous polymer is placed in deionized water to precipitate, washed with water, and then dried in an oven to obtain the polyamide copolymer.

[0030] Furthermore, the preparation method of the modified diamine prepolymer is as follows: 2,4-diaminobenzenesulfonic acid and anhydrous calcium chloride are heated to 80°C and dissolved in 30 mL of dimethylacetamide. Then, the mixture is transferred to a low-temperature circulating freeze bath at -5°C, and isophthaloyl chloride is slowly added and reacted for 20 min. The temperature is then increased to 10°C and reacted for 0.5 h. Then, m-phenylenediamine is added, and the reaction temperature is increased to 20°C and stirring is continued for 1 h. The resulting viscous polymer is placed in deionized water to precipitate, and after washing and drying, the modified diamine prepolymer is obtained. The molar ratio of 2,4-diaminobenzenesulfonic acid, anhydrous calcium chloride, isophthaloyl chloride, and m-phenylenediamine is 1:2:2:2, and the mass ratio of 2,4-diaminobenzenesulfonic acid to dimethylacetamide is 1:5.

[0031] In this embodiment, the compatibilizer is hexadecylamine; the lubricant is oleamide; and the oxidant is a mixture of octadecyl phosphate and antioxidant 1010 in a mass ratio of 3:1.

[0032] Example 2

[0033] A dyeable composite elastic fiber, wherein the composite elastic fiber is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips, wherein the thermoplastic polyester chips comprise the following raw materials in parts by weight: 72 parts of polypropylene terephthalate, 15 parts of polyamide copolymer, 4 parts of compatibilizer, 1 part of lubricant, and 0.6 parts of antioxidant.

[0034] In this embodiment, the preparation method of the modified PBT chips includes the following steps: (1) Terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, and the reaction is carried out at 240°C with stirring for 3 hours; (2) Sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to the reaction vessel, the reaction temperature is 240°C, the reaction pressure is controlled at about 60 Pa, the reaction time is 40 min, pre-polymerization is carried out, and then the reaction temperature is increased to 250°C, the reaction pressure is controlled at about 40 Pa, the reaction time is 2.5 h, and after the reaction is completed, the material is cooled and sliced ​​to obtain the modified PBT chips.

[0035] In step (1), the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediethanol is 1:1.7, the molar ratio of 1,4-cyclohexanediethanol to 1,4-butanediol is 1:2.2, and the added mass of tetrabutyl titanate is 0.03% of the added mass of terephthalic acid.

[0036] In step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 10% of the theoretical product mass.

[0037] In this embodiment, the intrinsic viscosity of the polypropylene terephthalate is 0.9 dL / g.

[0038] In this embodiment, the preparation method of the polyamide copolymer is as follows: m-phenylenediamine and modified diamine prepolymer with a molar ratio of 1:8.8 are added to 100 mL of dimethylacetamide solvent and stirred to dissolve. After dissolution, the solution is transferred to a constant temperature refrigeration circulating bath at about 0°C. Then, 18.2 g of isophthaloyl chloride is added dropwise, and the temperature is maintained at about 20°C while stirring for 1.5 h. 7.5 g of calcium hydroxide is added to obtain a viscous polymer. The viscous polymer is placed in deionized water to precipitate, washed with water, and then dried in an oven to obtain the polyamide copolymer.

[0039] Furthermore, the preparation method of the modified diamine prepolymer is as follows: 2,4-diaminobenzenesulfonic acid and anhydrous calcium chloride are heated to 85°C and dissolved in 30 mL of dimethylacetamide. Then, the mixture is transferred to a low-temperature circulating freeze bath at approximately 0°C, and isophthaloyl chloride is slowly added and reacted for 20 min. The temperature is then increased to 15°C and reacted for 0.5 h. Next, m-phenylenediamine is added, and the reaction temperature is increased to 20°C and stirring is continued for 1 h. Finally, the resulting viscous polymer is placed in deionized water to precipitate. After washing with water and drying, the modified diamine prepolymer is obtained. The molar ratio of 2,4-diaminobenzenesulfonic acid, anhydrous calcium chloride, isophthaloyl chloride, and m-phenylenediamine is 1:2:2:2, and the mass ratio of 2,4-diaminobenzenesulfonic acid to dimethylacetamide is 1:5.

[0040] In this embodiment, the compatibilizer is phenyl phthalate; the lubricant is liquid paraffin; and the oxidant is a mixture of trimethyl phosphate and antioxidant 1010 in a mass ratio of 2.5:1.

[0041] Example 3

[0042] A dyeable composite elastic fiber, wherein the composite elastic fiber is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips, wherein the thermoplastic polyester chips comprise the following raw materials in parts by weight: 80 parts of polypropylene terephthalate, 25 parts of polyamide copolymer, 8 parts of compatibilizer, 3 parts of lubricant, and 1 part of antioxidant.

[0043] In this embodiment, the preparation method of the modified PBT chips includes the following steps: (1) Terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, and the reaction is carried out at 250°C with stirring for 2.5 h; (2) Sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to the reaction vessel, the reaction temperature is 250°C, the reaction pressure is 80 Pa, the reaction time is 30 min, pre-polymerization is carried out, and then the reaction temperature is increased to 260°C, the reaction pressure is 40 Pa, the reaction time is 3 h, and after the reaction is completed, the material is cooled and sliced ​​to obtain the modified PBT chips.

[0044] In step (1), the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediethanol is 1:1.8, the molar ratio of 1,4-cyclohexanediethanol to 1,4-butanediol is 1:2.5, and the added mass of tetrabutyl titanate is 0.03% of the added mass of terephthalic acid.

[0045] In step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 20% of the theoretical product mass.

[0046] In this embodiment, the intrinsic viscosity of the polypropylene terephthalate is 0.9 dL / g.

[0047] In this embodiment, the preparation method of the polyamide copolymer is as follows: m-phenylenediamine and modified diamine prepolymer with a molar ratio of 1:9.2 are added to 110 mL of dimethylacetamide solvent and stirred to dissolve. After dissolution, the solution is transferred to a constant temperature refrigeration circulating bath at about 0°C. Then, 19.2 g of isophthaloyl chloride is added dropwise, and the temperature is maintained at 25°C while stirring for 2 hours. 8 g of calcium hydroxide is added to obtain a viscous polymer. The viscous polymer is placed in deionized water to precipitate, washed with water, and then dried in an oven to obtain the polyamide copolymer.

[0048] Furthermore, the preparation method of the modified diamine prepolymer is as follows: 2,4-diaminobenzenesulfonic acid and anhydrous calcium chloride are heated to 90°C and dissolved in 40 mL of dimethylacetamide. Then, the mixture is transferred to a low-temperature circulating freeze bath at 0°C, and isophthaloyl chloride is slowly added and reacted for 25 min. The temperature is then increased to 15°C and reacted for 1 h. Next, m-phenylenediamine is added, and the reaction temperature is increased to 25°C and stirring is continued for 1.5 h. Finally, the resulting viscous polymer is placed in deionized water to precipitate. After washing with water and drying, the modified diamine prepolymer is obtained. The molar ratio of 2,4-diaminobenzenesulfonic acid, anhydrous calcium chloride, isophthaloyl chloride, and m-phenylenediamine is 1:2:2:2, and the mass ratio of 2,4-diaminobenzenesulfonic acid to dimethylacetamide is 1:6.5.

[0049] In this embodiment, the compatibilizer is maleic anhydride-grafted polyethylene copolymer; the lubricant is ethylene difatty acid amine; and the oxidant is a mixture of trimethyl phosphite and antioxidant 168 in a mass ratio of 3:1.

[0050] Comparative Example 1

[0051] The difference between this comparative example and Example 2 is that the PBT chips prepared by the following method are used instead of the modified PBT in Example 2. The preparation method of the PBT chips includes the following steps: (1) Terephthalic acid, 1,4-butanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, and the reaction is carried out at 240°C with stirring for 3 hours; (2) Sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to the reaction vessel, the reaction temperature is 240°C, the reaction pressure is controlled at about 60 Pa, the reaction time is 40 min, pre-polymerization is carried out, and then the reaction temperature is increased to 240-260°C, the reaction pressure is controlled at about 40 Pa, the reaction time is 2.5 h, and after the reaction is completed, the material is cooled and sliced ​​to obtain the PBT chips.

[0052] In step (1), the total molar ratio of terephthalic acid to 1,4-butanediol is 1:1.7.

[0053] In step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 10% of the theoretical product mass.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 2 is that the PBT slices prepared by the following method are used instead of the modified PBT in Example 2. The preparation method of the PBT slices includes the following steps: terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, nitrogen gas is introduced into the reaction vessel, the reaction pressure is controlled at about 60 Pa, and the reaction is carried out at 240°C with stirring for 3.5 h; then the reaction temperature is increased to 250°C, the reaction pressure is controlled at about 40 Pa, and the reaction time is 2.5 h. After the reaction is completed, the material is cooled and sliced ​​to obtain the PBT slices.

[0056] In the above steps, the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediethanol is 1:1.7, and the molar ratio of 1,4-cyclohexanediethanol to 1,4-butanediol is 1:2.2.

[0057] Comparative Example 3

[0058] The difference between this comparative example and Example 2 is that the composite elastic fiber described in this comparative example is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips. The thermoplastic polyester chips include the following raw materials in parts by weight: 65-80 parts of polypropylene terephthalate, 2-8 parts of compatibilizer, 0.5-3 parts of lubricant, and 0.1-1 parts of antioxidant.

[0059] Example 4

[0060] The above-described embodiments 1-3 and comparative examples 1-3 of the present invention all employ the following method for preparing easily dyeable composite elastic fibers. The specific steps are as follows: thermoplastic polyester chips and modified PBT chips (or PBT chips) are placed in vacuum drying ovens at 130°C and 110°C respectively for drying for 6 hours; then, the dried thermoplastic polyester chips and modified PBT chips are placed in the two chambers of a twin-screw melt spinning machine at a mass ratio of 55:45 and heated to melt, wherein the spinning heating temperature of the modified PBT chips (or PBT chips) is 280°C, the spinning heating temperature of the thermoplastic polyester chips is 260°C, the spinning speed is 2600 m / min, and then the fibers are distributed by a spinneret and converged at the outlet of the spinneret. After air cooling, side-blowing cooling, stretching, oiling, and winding, the composite elastic fibers are obtained. The ring-blowing temperature is 30°C, the stretching ratio is 3 times, and the stretching temperature is 140°C.

[0061] The elastic fibers obtained in Examples 1-3 and Comparative Examples 1-3 were selectively subjected to mechanical property tests according to requirements. Among them, the breaking strength, breaking elongation and modulus were measured according to GB / T14337-2022 standard, the elastic recovery rate was measured according to ASTM D3107-2007 standard, and the boiling water shrinkage rate was measured according to GB / T6505-2001 standard. The test results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1 below.

[0062] Table 1 Performance test data of Examples 1-4 and Comparative Examples 1-3

[0063]

[0064] Furthermore, to verify the dyeing properties of the elastic fibers obtained in Example 2 and Comparative Examples 1-3, the elastic fibers obtained in Example 2 and Comparative Examples 1-3 were woven into greige fabric. After boiling, the greige fabric was dyed with 2% cationic red dye (X-GRL) at room temperature for 60 minutes. The color fastness of the dyed greige fabric was then tested. The water fastness was determined according to GB / T 5713-2013 standard, the rubbing fastness was determined according to GB / T 3920-2008 standard, and the perspiration fastness was determined according to GB / T 3922-2013 standard. The results are shown in Table 2 below.

[0065] Table 2. Results of water fastness and rubbing fastness tests for Examples 2 and Comparative Examples 1-3.

[0066]

[0067] As can be seen from the test results in Tables 1 and 2, the composite elastic fiber prepared in Example 2 of this invention exhibits excellent performance in terms of elongation at break, breaking strength, elastic recovery rate, modulus, and boiling water shrinkage, indicating that the composite elastic fiber possesses good comprehensive mechanical properties. Comparing Comparative Examples 1-2 with Example 2, it is evident that Example 2, by introducing 1,4-cyclohexanediethanol and sulfonic acid groups to modify PBT, effectively improves the strength and stability of PBT and significantly enhances its dyeing activity and color fastness to cationic dyes. Comparing Comparative Example 3 with Example 2, Example 2, by adding a polyamide copolymer during the preparation of thermoplastic polyester chips, significantly improves the strength and heat resistance of polypropylene terephthalate. This invention utilizes thermoplastic polyester chips and modified PBT chips for melt spinning, which can compensate for the performance defects of single PBT or thermoplastic polyester materials, resulting in a composite elastic fiber with excellent comprehensive performance and a wide range of applications.

[0068] The specific embodiments described above are further illustrations of the technical solution and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A dyeable composite elastic fiber, characterized in that: The composite elastic fiber is obtained by melt spinning of thermoplastic polyester chips and modified PBT chips. The thermoplastic polyester chips include the following raw materials in parts by weight: 65-80 parts of polypropylene terephthalate, 10-25 parts of polyamide copolymer, 2-8 parts of compatibilizer, 0.5-3 parts of lubricant, and 0.1-1 parts of antioxidant. The preparation method of the modified PBT chips includes the following steps: (1) terephthalic acid, 1,4-butanediol, 1,4-cyclohexanediol and tetrabutyl titanate are placed in a reaction vessel, and the reaction vessel is purged with... Nitrogen gas was introduced, and the mixture was stirred and reacted at 230-250℃ for 2-4 hours; (2) Sodium dihydroxyethyl isophthalate-5-sulfonate was added to the reactor, and the reaction temperature was 230-250℃, the reaction pressure was 20-80Pa, and the reaction time was 30-50min for pre-polymerization. Then the reaction temperature was increased to 240-260℃, the reaction pressure was 20-60Pa, and the reaction time was 2-3 hours. After the reaction was completed, the material was cooled and sliced ​​to obtain the modified PBT slices; the preparation method of the polyamide copolymer has The preparation method is as follows: m-phenylenediamine and the modified diamine prepolymer are added to 90-110 mL of dimethylacetamide solvent and stirred until dissolved. After dissolution, the solution is transferred to a constant temperature refrigeration circulating bath at -5-0℃. Then, 17.5-19.2 g of isophthaloyl chloride is added dropwise, and the mixture is stirred at 15-25℃ for 1-2 hours. 7-8 g of calcium hydroxide is added to obtain a viscous polymer. This viscous polymer is then placed in deionized water to precipitate, washed with water, and dried in an oven to obtain the polyamide copolymer. The specific preparation method of the modified diamine prepolymer is detailed below. The process involves heating 2,4-diaminobenzenesulfonic acid and anhydrous calcium chloride to 80-90℃ and dissolving them in 30-40 mL of dimethylacetamide. The mixture is then transferred to a low-temperature circulating freeze bath at -5-0℃, and isophthaloyl chloride is slowly added and reacted for 20-25 min. The temperature is then increased to 10-15℃ and reacted for 0.5-1 h. Next, m-phenylenediamine is added, and the reaction temperature is increased to 20-25℃ with continued stirring for 1-1.5 h. Finally, the resulting viscous polymer is placed in deionized water to precipitate, and after washing and drying, the modified diamine prepolymer is obtained.

2. The easily dyeable composite elastic fiber according to claim 1, characterized in that: The modified PBT chips have sulfonic acid groups randomly distributed on their molecular chains.

3. The easily dyeable composite elastic fiber according to claim 1, characterized in that: In step (1), the total molar ratio of terephthalic acid to 1,4-butanediol and 1,4-cyclohexanediethanol is 1:1.6-1.8, and the molar ratio of 1,4-cyclohexanediethanol to 1,4-butanediol is 1:2-2.

5.

4. The easily dyeable composite elastic fiber according to claim 1, characterized in that: In step (2), the mass of sodium bis(hydroxyethyl) isophthalate-5-sulfonate is 5-20% of the theoretical product mass.

5. The easily dyeable composite elastic fiber according to claim 1, characterized in that: The molar ratio of the modified diamine prepolymer to m-phenylenediamine is 1:8.5-9.

2.

6. The easily dyeable composite elastic fiber according to claim 1, characterized in that: The compatibilizer is at least one of hexadecylamine, phenyl phthalate, polyethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and maleic anhydride-grafted polyethylene copolymer.

7. The easily dyeable composite elastic fiber according to claim 1, characterized in that: The lubricant is at least one of liquid paraffin, organosilane, oleamide, and ethylene diamino acid amine.

8. A method for preparing easily dyeable composite elastic fiber as described in claim 1, characterized in that: The process includes the following steps: thermoplastic polyester chips and modified PBT chips are dried in vacuum drying ovens at 120-140℃ and 110-120℃ respectively for 4-12 hours; then, the dried thermoplastic polyester chips and modified PBT chips are heated and melted in a twin-screw melt spinning machine at a mass ratio of 30:70-70:30, then distributed by a spinneret and merged at the outlet of the spinneret, and then cooled by air, cooled by side blowing, drawn, oiled, and wound to obtain the composite elastic fiber.

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