Modified polytrimethylene terephthalate and preparation method thereof

Abstract

The invention relates to the technical field of polyester modification, and discloses modified polytrimethylene terephthalate and a preparation method thereof. The modified polytrimethylene terephthalate is formed by copolymerizing monomers including 1, 3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol; the modified polyethylene glycol is polyethylene glycol with a sulfonic acid group on a side chain. According to the invention, furandicarboxylic acid and polyethylene glycol with a sulfonic acid group on a side chain are introduced into PTT, so that PTT can have better dyeability and color fastness during cationic dye dyeing.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester modification, in particular to modified poly(trimethylene terephthalate) and a preparation method thereof. Background Art

[0002] Polytrimethylene terephthalate (PTT) is a new polyester product. Its unique bio-based raw materials give it great development potential in markets focused on environmental sustainability. PTT fiber offers excellent elasticity, soft fabric, high elongation recovery, excellent dyeing and printing properties, and high color fastness and light fastness. It can be spun pure or in blends, and is suitable for the production of apparel such as carpets, fashion, sportswear, and underwear.

[0003] The surface morphology of PTT fiber is in the shape of smooth strips, and it has strong light reflection and refraction, and the fiber has a strong luster; there are gaps on the surface, which has certain moisture conductivity, breathability and warmth retention; it can be made into fiber products with various cross-sectional shapes, and can also be directly processed into colored PTT fibers during the manufacturing process, which is convenient for selection. The "Z"-shaped spiral structure of PTT fiber gives it high elasticity and good resilience that are superior to other fibers. In addition, compared with polyethylene terephthalate (PET), the special structure of PTT can improve its dyeing performance, but PTT still lacks polar groups, so it can only achieve good disperse dye dyeability. When dyed with cationic dyes, the dyeability is poor and the color fastness is low.

[0004] Patent CN103183817B discloses a modified PTT copolyester, its preparation method, and application. By adding sodium 5-sulfoisophthalate and aliphatic polyether to the polymerization process of PTT for chemical copolymerization, the sulfonic acid group can be used to adsorb cationic dyes, and the aliphatic polyether can be used to lower the glass transition temperature of the polyester, thereby improving the dyeability and color fastness of PTT when dyed with cationic dyes to a certain extent, but the effect is limited. Although increasing the amount of sodium 5-sulfoisophthalate and aliphatic polyether can further improve the cationic dye dyeability and color fastness of PTT, it will cause poor mechanical properties of PTT fibers. Summary of the Invention

[0005] To address the technical problem of limited effectiveness of existing methods for improving the dyeability and color fastness of PTT with cationic dyes, the present invention provides a modified poly(trimethylene terephthalate) and a method for preparing the same. By introducing furandicarboxylic acid and polyethylene glycol with sulfonic acid groups on its side chains into PTT, the present invention improves PTT's dyeability and color fastness when dyed with cationic dyes.

[0006] The specific technical solutions of the present invention are: Disclosed is a modified poly(trimethylene terephthalate), which is formed by copolymerizing monomers including 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol; the modified polyethylene glycol is polyethylene glycol with a sulfonic acid group on the side chain.

[0007] In the present invention, furandicarboxylic acid and modified polyethylene glycol are added as comonomers during the polymerization process for preparing PTT, thereby significantly improving the dyeability and color fastness of PTT when dyed with cationic dyes. Specifically: (1) By introducing furandicarboxylic acid monomers, the symmetry and rigidity of the PTT molecular chain can be destroyed, and polar groups can be introduced, thereby improving the cationic dyeability and color fastness of PTT to a certain extent; at the same time, the introduction of furandicarboxylic acid monomers can also improve the thermomechanical properties of PTT.

[0008] (2) In the modified polyethylene glycol used in the present invention, on the one hand, the polyethylene glycol chain segment has high flexibility and is prone to chain segment movement, which can form an amorphous region in the modified PTT, and cationic dyes can easily enter and diffuse in the region. Since the sulfonic acid group is connected to the side chain of polyethylene glycol, the polyethylene glycol chain segment can be used to promote the combination of the sulfonic acid group and the cationic dye, and the sulfonic acid group can be used to make the cationic dye entering the amorphous region stably bonded therein; on the other hand, the side chain with the sulfonic acid group can improve the local rigidity in the modified polyethylene glycol chain segment, so that the surrounding molecular chains cannot be closely arranged, thereby making the amorphous region formed by the polyethylene glycol segment have more pores, making it easier for cationic dyes to enter the region. Through the above two effects, compared with introducing monomers containing sulfonic acid groups and polyethylene glycol separately into the PTT molecular chain, the present invention uses polyethylene glycol with sulfonic acid groups on the side chain, which can improve the cationic dye dyeability and color fastness of the modified PTT to a greater extent.

[0009] Preferably, the modified polyethylene glycol is formed by carrying out ring-opening polymerization of ethylene oxide and allyl glycidyl ether using 4-phenylenediol as an initiator, and then grafting 3-mercapto-1-propanesulfonate via a mercapto-ene click reaction.

[0010] Ring-opening polymerization of ethylene oxide and allyl glycidyl ether forms polyethylene glycol with alkenyl side chains. Sulfonic acid groups are then attached to the side chains of the polyethylene glycol through a click reaction between the alkenyl and thiol groups. The present invention uses p-terephthalate dimethanol as an initiator for the ring-opening polymerization reaction, utilizing the benzene ring structure to restrict the movement of surrounding molecular chains, thereby imparting improved cationic dyeability and color fastness to the modified PTT.

[0011] Furthermore, the molar ratio between the ethylene oxide and allyl glycidyl ether is 1:0.1-0.3; the molar ratio between the terephthalic acid methanol and ethylene oxide is 1:50-100; and the molar ratio between the allyl glycidyl ether and 3-mercapto-1-propanesulfonate is 1:1-1.5.

[0012] Within a certain range, by increasing the proportion of ethylene oxide and allyl glycidyl ether, more sulfonic acid groups can be introduced into polyethylene glycol, thereby improving the cationic dye dyeability and color fastness of the modified PTT; however, when the molar ratio between ethylene oxide and allyl glycidyl ether is higher than 1:0.3 (too much allyl glycidyl ether), it will excessively affect the flexibility of the polyethylene glycol chain segment, which is not conducive to the cationic dye entering the amorphous region formed by the modified polyethylene glycol and combining with the sulfonic acid groups, thereby adversely affecting the cationic dye dyeability of the modified PTT.

[0013] Preferably, among the 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol, the mass proportion of modified polyethylene glycol is 3-6%, the mass proportion of 1,3-propylene glycol is 35-40%, and the mass ratio of furandicarboxylic acid to terephthalic acid is 1:2-9.

[0014] A preparation method of the modified poly(trimethylene terephthalate) comprises the following steps: mixing 1,3-propylene glycol, furandicarboxylic acid and terephthalic acid to carry out an esterification reaction, adding a polycondensation catalyst and modified polyethylene glycol to carry out a polycondensation reaction to obtain the modified poly(trimethylene terephthalate).

[0015] Preferably, the preparation steps of the modified polyethylene glycol include: mixing terephthalate, ethylene oxide, allyl glycidyl ether, a ring-opening reaction catalyst and a ring-opening reaction solvent, performing ring-opening polymerization, mixing the resulting product with 3-mercapto-1-propanesulfonate, a click reaction catalyst and a click reaction solvent, performing a thiol-ene click reaction, and separating the product to obtain the modified polyethylene glycol.

[0016] Furthermore, the ring-opening reaction catalyst is an organic phosphazene base and triethyl boron; the ring-opening polymerization is carried out in an inert atmosphere at a temperature of 30 to 50° C. for 12 to 15 hours.

[0017] Furthermore, the molar ratio of the ethylene oxide to the ring-opening reaction catalyst is 1:0.005-0.01; the molar ratio of the organic phosphazene base to triethylboron is 1:1-5; and the mass-to-volume ratio of the ethylene oxide to the ring-opening reaction solvent is 30-40 g:100 mL.

[0018] Furthermore, the click reaction catalyst is azobisisobutyronitrile; the thiol-ene click reaction is carried out in an inert atmosphere at a temperature of 60 to 70° C. for 12 to 24 hours.

[0019] Furthermore, the molar ratio of the 3-mercapto-1-propanesulfonate to the click reaction catalyst is 1:0.03-0.07; the mass-to-volume ratio of the 3-mercapto-1-propanesulfonate to the click reaction solvent is 30-40 g:100 mL.

[0020] Preferably, the temperature of the esterification reaction is 200-240°C.

[0021] Preferably, the polycondensation catalyst is n-butyl titanate, and the amount used is 100-150 ppm of the theoretical output of modified poly(trimethylene terephthalate); the vacuum degree of the polycondensation reaction is not higher than 30 Pa, and the temperature is 260-280°C.

[0022] Compared with the prior art, the present invention has the following advantages: (1) The present invention can improve the cationic dyeability and thermomechanical properties of PTT by introducing furandicarboxylic acid monomer as a comonomer during the polymerization process of PTT.

[0023] (2) The present invention introduces polyethylene glycol with a sulfonic acid group on the side chain as a comonomer during the polymerization process for preparing PTT. Compared with introducing monomers containing sulfonic acid groups and polyethylene glycol separately into the PTT molecular chain, the cationic dyeability and color fastness of PTT can be improved to a greater extent.

[0024] (3) In the process of preparing modified polyethylene glycol, the present invention uses terephthalate as the initiator of the ring-opening polymerization reaction and controls the molar ratio between ethylene oxide and allyl glycidyl ether to be 1:0.1-0.3, thereby giving the modified PTT better cationic dyeability and color fastness. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the embodiments.

[0026] Overall embodiment Disclosed is a modified poly(trimethylene terephthalate), which is formed by copolymerizing monomers including 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol; the modified polyethylene glycol is polyethylene glycol with a sulfonic acid group on the side chain.

[0027] In some specific embodiments, the modified polyethylene glycol is formed by ring-opening polymerization of ethylene oxide and allyl glycidyl ether using p-terephthalate as an initiator, followed by grafting 3-mercapto-1-propanesulfonate via a thiol-ene click reaction. Optionally or preferably, the molar ratio of ethylene oxide to allyl glycidyl ether is 1:0.1 to 0.3; the molar ratio of p-terephthalate to ethylene oxide is 1:50 to 100; and the molar ratio of allyl glycidyl ether to 3-mercapto-1-propanesulfonate is 1:1 to 1.5.

[0028] In some specific embodiments, among the 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol, the mass proportion of modified polyethylene glycol is 3-6%, the mass proportion of 1,3-propylene glycol is 35-40%, and the mass ratio between furandicarboxylic acid and terephthalic acid is 1:2-9.

[0029] A preparation method of the modified poly(trimethylene terephthalate) comprises the following steps: mixing 1,3-propylene glycol, furandicarboxylic acid and terephthalic acid to carry out an esterification reaction, adding a polycondensation catalyst and modified polyethylene glycol to carry out a polycondensation reaction to obtain the modified poly(trimethylene terephthalate).

[0030] In some specific embodiments, the preparation steps of the modified polyethylene glycol include: mixing terephthalate, ethylene oxide, allyl glycidyl ether, a ring-opening reaction catalyst, and a ring-opening reaction solvent, performing ring-opening polymerization, mixing the resulting product with 3-mercapto-1-propanesulfonate, a click reaction catalyst, and a click reaction solvent, performing a thiol-ene click reaction, and separating the product to obtain the modified polyethylene glycol. Among them, optionally or preferably: During the ring-opening polymerization reaction, the ring-opening reaction catalyst is an organic phosphazene base and triethylboron in a molar ratio of 1:1-5, the molar ratio of ethylene oxide to the ring-opening reaction catalyst is 1:0.005-0.01; the mass volume ratio of ethylene oxide to the ring-opening reaction solvent is 30-40 g:100 mL; the ring-opening polymerization is carried out in an inert atmosphere at a temperature of 30-50° C. for 12-15 hours; During the click reaction process: the click reaction catalyst is azobisisobutyronitrile, the molar ratio between 3-mercapto-1-propanesulfonate and the click reaction catalyst is 1:0.03-0.07; the mass volume ratio between the 3-mercapto-1-propanesulfonate and the click reaction solvent is 30-40 g:100 mL; the thiol-ene click reaction is carried out in an inert atmosphere at a temperature of 60-70°C and a time of 12-24 h.

[0031] In some embodiments, the temperature of the esterification reaction is 200-240°C.

[0032] In some specific embodiments, the polycondensation catalyst is n-butyl titanate, and the amount used is 100-150 ppm of the theoretical yield of modified poly(trimethylene terephthalate); the vacuum degree of the polycondensation reaction is not higher than 30 Pa, and the temperature is 260-280°C.

[0033] Example The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0035] Example 1 The modified poly(trimethylene terephthalate) of this embodiment was prepared by the following steps, and its performance was tested: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether in a molar ratio of 1:0.2 as polymerization monomers, take 1.5% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base in a molar ratio of 1:3 t BuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-terephthalate, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 40-45°C for 14 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0036] Sodium 3-mercapto-1-propanesulfonate is used as a modifier in an amount equimolar to allyl glycidyl ether, azobisisobutyronitrile is used as a catalyst at 5% of the molar amount of sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran is used as the reaction solvent at a mass volume ratio of 35 g:100 mL. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 60-65° C. for 18 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved with ether, filtered, and the filtrate is distilled under reduced pressure to obtain modified polyethylene glycol.

[0037] (2) Esterification, polycondensation reaction and chip intrinsic viscosity and melting point test: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol are used as polymerization monomers in a mass ratio of 1:9:6.5:0.8. 100 ppm of n-butyl titanate, equivalent to the theoretical yield (mass) of modified PTT, is used as a catalyst. Furandicarboxylic acid and terephthalic acid are added to a reactor, along with 1,3-propylene glycol. The temperature is maintained at 200-210°C for esterification. The reaction ends when water is produced during esterification, yielding an esterified product. n-butyl titanate and modified polyethylene glycol are added to the esterified product. After stirring for 30 minutes, the vacuum system is activated. Low vacuum is slowly reduced to -100 kPa over 1 hour, followed by high vacuum, maintaining the vacuum at no more than 30 Pa. The temperature is maintained at 260-280°C for polycondensation. The reaction is terminated when the specified discharge viscosity is reached, yielding modified PTT, which is then pelletized to obtain modified PTT chips.

[0038] The results show that the intrinsic viscosity of the modified PTT slice is 0.648 and the melting point is 210℃.

[0039] (3) Spinning, weaving and fabric cationic dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0040] Fabric was dyed using methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 98%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded 4-5.

[0041] Example 2 The modified poly(trimethylene terephthalate) of this embodiment was prepared by the following steps, and its performance was tested: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether in a molar ratio of 1:0.3 as polymerization monomers, take 2% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base in a molar ratio of 1:3 t BuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-phenylenediol, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 45-50°C for 12 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0042] The method comprises the following steps: using sodium 3-mercapto-1-propanesulfonate in a molar amount 1.5 times that of allyl glycidyl ether as a modifier, using azobisisobutyronitrile in a molar amount 5% of the amount of sodium 3-mercapto-1-propanesulfonate as a catalyst, and using tetrahydrofuran as a reaction solvent at a mass volume ratio of 35 g:100 mL of 3-mercapto-1-propanesulfonate to tetrahydrofuran. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and then the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 60-65° C. for 24 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved in ether, filtered, and the filtrate is distilled under reduced pressure to obtain a modified polyethylene glycol.

[0043] (2) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol were used as polymerization monomers in a mass ratio of 2:8:7:0.5, and 100 ppm of n-butyl titanate (the theoretical yield of modified PTT) was used as a catalyst. Furandicarboxylic acid and terephthalic acid were added to a reactor, along with 1,3-propylene glycol. The temperature was maintained at 220-230°C for esterification. The reaction was terminated when water was completely discharged, yielding an esterified product. n-butyl titanate and modified polyethylene glycol were added to the esterified product. After stirring for 30 minutes, the vacuum system was activated and the vacuum was slowly reduced to -100 kPa over 1 hour. High vacuum was then applied, maintaining the vacuum at no more than 30 Pa. The temperature was maintained at 260-280°C for polycondensation. The reaction was terminated when the specified discharge viscosity was reached, yielding modified PTT, which was then pelletized to obtain modified PTT chips.

[0044] The results show that the intrinsic viscosity of the modified PTT slice is 0.727 and the melting point is 208℃.

[0045] (3) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0046] Fabric was dyed using methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 96%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded 4-5.

[0047] Example 3 The modified poly(trimethylene terephthalate) of this embodiment was prepared by the following steps, and its performance was tested: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether in a molar ratio of 1:0.1 as polymerization monomers, take 1% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base in a molar ratio of 1:3 t BuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-phenylenediol, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 30-35°C for 15 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0048] The method comprises the following steps: using sodium 3-mercapto-1-propanesulfonate in a molar amount 1.5 times that of allyl glycidyl ether as a modifier, using azobisisobutyronitrile in a molar amount 5% of the amount of sodium 3-mercapto-1-propanesulfonate as a catalyst, and using tetrahydrofuran as a reaction solvent at a mass volume ratio of 35 g:100 mL of 3-mercapto-1-propanesulfonate to tetrahydrofuran. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and then the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 65-70° C. for 12 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved in ether, filtered, and the filtrate is distilled under reduced pressure to obtain a modified polyethylene glycol.

[0049] (2) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol were used as polymerization monomers in a mass ratio of 3:7:7.5:1.1, and n-butyl titanate (100 ppm, which corresponds to the theoretical yield (mass) of modified PTT) was used as a catalyst. Furandicarboxylic acid and terephthalic acid were added to a reactor, along with 1,3-propylene glycol. The temperature was maintained at 230-240°C for the esterification reaction. The reaction was terminated when water was completely discharged, yielding an esterified product. n-butyl titanate and modified polyethylene glycol were added to the esterified product. After stirring for 30 minutes, the vacuum system was activated and the vacuum was slowly reduced to -100 kPa over 1 hour. High vacuum was then applied, maintaining the vacuum at no more than 30 Pa. The temperature was maintained at 260-280°C for the polycondensation reaction. The reaction was terminated when the specified discharge viscosity was reached, yielding modified PTT, which was then pelletized to obtain modified PTT chips.

[0050] The results show that the intrinsic viscosity of the modified PTT slice is 0.565 and the melting point is 201°C.

[0051] (3) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0052] Fabric was dyed using methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 97%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded 4-5.

[0053] Example 4 The modified poly(trimethylene terephthalate) of this embodiment was prepared by the following steps, and its performance was tested: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether in a molar ratio of 1:0.2 as polymerization monomers, take 1% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base in a molar ratio of 1:3 t BuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-terephthalate, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 40-45°C for 14 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0054] Sodium 3-mercapto-1-propanesulfonate is used as a modifier in an amount equimolar to allyl glycidyl ether, azobisisobutyronitrile is used as a catalyst at 5% of the molar amount of sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran is used as the reaction solvent at a mass volume ratio of 35 g:100 mL. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 60-65° C. for 18 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved with ether, filtered, and the filtrate is distilled under reduced pressure to obtain modified polyethylene glycol.

[0055] (2) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol were used as polymerization monomers in a mass ratio of 3:7:7:0.9, and n-butyl titanate (100 ppm, which corresponds to the theoretical yield (mass) of modified PTT) was used as a catalyst. Furandicarboxylic acid and terephthalic acid were added to a reactor, along with 1,3-propylene glycol. The temperature was maintained at 230-240°C for the esterification reaction. The reaction was terminated when water was completely discharged, yielding an esterified product. n-butyl titanate and modified polyethylene glycol were added to the esterified product. After stirring for 30 minutes, the vacuum system was activated and the vacuum was slowly reduced to -100 kPa over 1 hour. High vacuum was then applied, maintaining the vacuum at no more than 30 Pa. The temperature was maintained at 260-280°C for the polycondensation reaction. The reaction was terminated when the specified discharge viscosity was reached, yielding modified PTT, which was then pelletized to obtain modified PTT chips.

[0056] The results show that the intrinsic viscosity of the modified PTT slice is 0.667 and the melting point is 203℃.

[0057] (3) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0058] Fabric was dyed using methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 98%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded 4-5.

[0059] Comparative Example 1 The only difference between this comparative example and Example 2 is that polyethylene glycol and 5-sodium sulfoisophthalate are used instead of modified polyethylene glycol. The specific steps for preparing modified poly(trimethylene terephthalate) and conducting performance tests in this comparative example are as follows: (1) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, sodium 5-sulfoisophthalate, and polyethylene glycol PEG-4000 are used as polymerization monomers in a mass ratio of 2:8:7:0.5:0.5. A catalyst is used, with 100 ppm of n-butyl titanate (theoretical yield of modified PTT) as the catalyst. Furandicarboxylic acid and terephthalic acid are added to a reactor, along with 1,3-propylene glycol. The esterification reaction is carried out at a temperature maintained at 220-230°C. The reaction ends when water is produced, yielding the esterified product. Add n-butyl titanate and modified polyethylene glycol to the esterification product, stir for 30 minutes, turn on the vacuum system, slowly draw low vacuum down to -100kPa on the pressure gauge within 1 hour, then enter high vacuum, keep the vacuum degree no higher than 30Pa, maintain the temperature at 260-280℃ for polycondensation reaction, terminate the reaction when the specified discharge viscosity is reached, and obtain modified PTT, which is then pelletized to obtain modified PTT chips.

[0060] The results showed that the intrinsic viscosity of the modified PTT slice was 0.670 and the melting point was 199°C.

[0061] (2) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0062] Fabric was dyed using methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dyed fabric was tested for color fastness to washing with soap according to "GB / T 3921-2008 Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap." After 30 washes, the color fastness was graded 3-4.

[0063] Comparing the test results of Example 2 and Comparative Example 1, it can be seen that compared to introducing a monomer containing a sulfonic acid group and polyethylene glycol separately into the PTT molecular chain, the present invention uses polyethylene glycol with sulfonic acid groups on the side chain, which can significantly improve the cationic dye dyeability and color fastness of the modified PTT. The reason for this is that, on the one hand, the polyethylene glycol segments in the modified polyethylene glycol used in the present invention have high flexibility and are prone to segmental movement, forming amorphous regions within the modified PTT, where cationic dyes can easily enter and diffuse. Because the sulfonic acid groups are attached to the side chains of the polyethylene glycol, the polyethylene glycol segments can promote the binding of the sulfonic acid groups with the cationic dyes, and the sulfonic acid groups can also stabilize the cationic dyes that enter the amorphous regions. On the other hand, the side chains with sulfonic acid groups can increase the local rigidity within the modified polyethylene glycol segments, preventing the surrounding molecular chains from being tightly arranged. This results in more pores within the amorphous regions formed by the polyethylene glycol segments, making it easier for cationic dyes to enter these regions.

[0064] Comparative Example 2 The only difference between this comparative example and Example 2 is that the amount of allyl glycidyl ether relative to ethylene oxide was increased during the preparation of the modified polyethylene glycol. The specific steps for preparing the modified poly(trimethylene terephthalate) in this comparative example and conducting the performance test are as follows: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether in a molar ratio of 1:0.6 as polymerization monomers, take 2% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base in a molar ratio of 1:3 tBuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-phenylenediol, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 45-50°C for 12 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0065] The method comprises the following steps: using sodium 3-mercapto-1-propanesulfonate in a molar amount 1.5 times that of allyl glycidyl ether as a modifier, using azobisisobutyronitrile in a molar amount 5% of the amount of sodium 3-mercapto-1-propanesulfonate as a catalyst, and using tetrahydrofuran as a reaction solvent at a mass volume ratio of 35 g:100 mL of 3-mercapto-1-propanesulfonate to tetrahydrofuran. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and then the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 60-65° C. for 24 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved in ether, filtered, and the filtrate is distilled under reduced pressure to obtain a modified polyethylene glycol.

[0066] (2) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol were used as polymerization monomers in a mass ratio of 2:8:7:0.5, and 100 ppm of n-butyl titanate (the theoretical yield of modified PTT) was used as a catalyst. Furandicarboxylic acid and terephthalic acid were added to a reactor, along with 1,3-propylene glycol. The temperature was maintained at 220-230°C for esterification. The reaction was terminated when water was completely discharged, yielding an esterified product. n-butyl titanate and modified polyethylene glycol were added to the esterified product. After stirring for 30 minutes, the vacuum system was activated and the vacuum was slowly reduced to -100 kPa over 1 hour. High vacuum was then applied, maintaining the vacuum at no more than 30 Pa. The temperature was maintained at 260-280°C for polycondensation. The reaction was terminated when the specified discharge viscosity was reached, yielding modified PTT, which was then pelletized to obtain modified PTT chips.

[0067] The results show that the intrinsic viscosity of the modified PTT slice is 0.687 and the melting point is 204℃.

[0068] (3) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0069] Fabric was dyed with methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid in the dye liquor. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 90%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded 4-5.

[0070] Comparing the test results of Example 2 and Comparative Example 2 reveals that, during the preparation of modified polyethylene glycol, excessively high molar ratios of ethylene oxide to allyl glycidyl ether (excessive allyl glycidyl ether content) can result in decreased cationic dyeability of the modified PTT. This is attributed to the fact that excessive amounts of allyl glycidyl ether relative to ethylene oxide excessively affect the flexibility of the polyethylene glycol segments, hindering the ability of cationic dyes to enter the amorphous regions formed by the modified polyethylene glycol and bind to the sulfonic acid groups.

[0071] Comparative Example 3 The only difference between this comparative example and Example 3 is that the amount of allyl glycidyl ether relative to ethylene oxide was reduced during the preparation of the modified polyethylene glycol. The specific steps for preparing the modified poly(trimethylene terephthalate) in this comparative example and conducting the performance test are as follows: (1) Preparation of modified polyethylene glycol: Take ethylene oxide and allyl glycidyl ether with a molar ratio of 1:0.05 as polymerization monomers, take 1% of the molar amount of ethylene oxide as the initiator, take organic phosphazene base with a molar ratio of 1:3 t BuP1 and triethylboron are used as catalysts, with the catalyst amount being 0.6% of the molar amount of ethylene oxide. Tetrahydrofuran is used as the reaction solvent, with a mass volume ratio of ethylene oxide to tetrahydrofuran of 35g:100mL. Tetrahydrofuran is added to a reactor, the air in the reactor is replaced with nitrogen, and the temperature is lowered to 0°C. Then, p-phenylenediol, ethylene oxide, and allyl glycidyl ether are added and stirred to dissolve. An organophosphazene base and triethylboron are then added, and the temperature is maintained at 30-35°C for 15 hours. Then, n-hexane is added to precipitate the product, which is then filtered to obtain alkenyl-polyethylene glycol.

[0072] The method comprises the following steps: using sodium 3-mercapto-1-propanesulfonate in a molar amount 1.5 times that of allyl glycidyl ether as a modifier, using azobisisobutyronitrile in a molar amount 5% of the amount of sodium 3-mercapto-1-propanesulfonate as a catalyst, and using tetrahydrofuran as a reaction solvent at a mass volume ratio of 35 g:100 mL of 3-mercapto-1-propanesulfonate to tetrahydrofuran. Alkenyl-polyethylene glycol, sodium 3-mercapto-1-propanesulfonate, and tetrahydrofuran are added to a reactor, stirred and dissolved, and then the air in the reactor is replaced with nitrogen. Azobisisobutyronitrile is then added, and the temperature is maintained at 65-70° C. for 12 hours. The solvent is removed by distillation under reduced pressure, and the mixture is dissolved in ether, filtered, and the filtrate is distilled under reduced pressure to obtain a modified polyethylene glycol.

[0073] (2) Esterification and polycondensation reaction: Furandicarboxylic acid, terephthalic acid, 1,3-propylene glycol, and modified polyethylene glycol were used as polymerization monomers in a mass ratio of 3:7:7.5:1.1, and n-butyl titanate (100 ppm, which corresponds to the theoretical yield (mass) of modified PTT) was used as a catalyst. Furandicarboxylic acid and terephthalic acid were added to a reactor, along with 1,3-propylene glycol. The temperature was maintained at 230-240°C for the esterification reaction. The reaction was terminated when water was completely discharged, yielding an esterified product. n-butyl titanate and modified polyethylene glycol were added to the esterified product. After stirring for 30 minutes, the vacuum system was activated and the vacuum was slowly reduced to -100 kPa over 1 hour. High vacuum was then applied, maintaining the vacuum at no more than 30 Pa. The temperature was maintained at 260-280°C for the polycondensation reaction. The reaction was terminated when the specified discharge viscosity was reached, yielding modified PTT, which was then pelletized to obtain modified PTT chips.

[0074] The results show that the intrinsic viscosity of the modified PTT slice is 0.579 and the melting point is 205℃.

[0075] (3) Cationic dye dyeing performance test: The modified PTT slices were spun to obtain modified PTT fibers with a specification of 75D / 72F, which were then woven with a twist of 900 twists / m, a warp density of 200 strands / inch, and a weft density of 120 strands / inch to obtain a high-density plain weave fabric.

[0076] Fabric was dyed with methylene blue as a cationic dye at a bath ratio of 1:100, a dye concentration of 5% owf, a pH of 4.5, and 1% acetic acid. The dyeing temperature was 80°C, and the dyeing time was 3 hours. The dye uptake was measured to be 90%. The dyed fabric was tested for color fastness to washing with soap according to GB / T 3921-2008, Textiles - Tests for Color Fastness - Color Fastness to Washing with Soap. After 30 washes, the color fastness was graded as 4.

[0077] Comparing the test results of Example 3 and Comparative Example 3 reveals that, during the preparation of modified polyethylene glycol, when the molar ratio of ethylene oxide to allyl glycidyl ether is too low (too little allyl glycidyl ether is present), the cationic dyeability and color fastness of the modified PTT decrease. This is due to the fact that when the amount of allyl glycidyl ether relative to ethylene oxide is too low, the modified PTT contains fewer sulfonic acid groups, which negatively impacts its cationic dyeability.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A modified poly(trimethylene terephthalate), characterized in that: The modified poly(trimethylene terephthalate) is formed by copolymerizing monomers including 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol; the modified polyethylene glycol is polyethylene glycol with a sulfonic acid group on the side chain.

2. The modified polytrimethylene terephthalate according to claim 1, wherein The modified polyethylene glycol is formed by carrying out ring-opening polymerization of ethylene oxide and allyl glycidyl ether with p-phenylenediol as an initiator, and then grafting 3-mercapto-1-propanesulfonate through a mercapto-ene click reaction.

3. The modified polytrimethylene terephthalate according to claim 2, wherein The molar ratio of ethylene oxide to allyl glycidyl ether is 1:0.1-0.3; the molar ratio of terephthalic acid methanol to ethylene oxide is 1:50-100; and the molar ratio of allyl glycidyl ether to 3-mercapto-1-propanesulfonate is 1:1-1.

5.

4. The modified polytrimethylene terephthalate according to claim 1, wherein Among the 1,3-propylene glycol, furandicarboxylic acid, terephthalic acid and modified polyethylene glycol, the mass proportion of modified polyethylene glycol is 3-6%, the mass proportion of 1,3-propylene glycol is 35-40%, and the mass ratio between furandicarboxylic acid and terephthalic acid is 1:2-9.

5. A method for preparing the modified poly(trimethylene terephthalate) according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: mixing 1,3-propylene glycol, furandicarboxylic acid and terephthalic acid to carry out esterification reaction, adding a polycondensation catalyst and modified polyethylene glycol to carry out polycondensation reaction to obtain modified poly(trimethylene terephthalate).

6. The preparation method according to claim 5, characterized in that The preparation steps of the modified polyethylene glycol include: mixing terephthalate, ethylene oxide, allyl glycidyl ether, a ring-opening reaction catalyst and a ring-opening reaction solvent, performing ring-opening polymerization, mixing the obtained product with 3-mercapto-1-propanesulfonate, a click reaction catalyst and a click reaction solvent, performing a mercapto-ene click reaction, and separating the product to obtain the modified polyethylene glycol.

7. The preparation method according to claim 6, characterized in that The ring-opening reaction catalyst is an organic phosphazene base and triethyl boron; the ring-opening polymerization is carried out in an inert atmosphere at a temperature of 30-50° C. for 12-15 hours.

8. The preparation method according to claim 6, characterized in that The click reaction catalyst is azobisisobutyronitrile; the thiol-ene click reaction is carried out in an inert atmosphere at a temperature of 60-70° C. for 12-24 hours.

9. The preparation method according to claim 5, characterized in that The temperature of the esterification reaction is 200-240°C.

10. The preparation method according to claim 5, characterized in that The polycondensation catalyst is n-butyl titanate, and the dosage is 100-150 ppm of the theoretical output of modified poly(trimethylene terephthalate); the vacuum degree of the polycondensation reaction is not higher than 30 Pa, and the temperature is 260-280°C.