Modified copolyester, preparation method thereof and polyester fiber product

Abstract

The invention relates to the field of polyester fiber production, and discloses modified copolyester, a preparation method thereof and a polyester fiber product. The modified copolyester contains a structural unit A as shown in a formula (I), a structural unit B as shown in a formula (II) and a structural unit C as shown in a formula (III), wherein R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, and m is a positive integer greater than 3; rI, RII, and RIII are each independently hydrogen or a C1-C10 alkyl group. The preparation method comprises the following step: in the presence of a catalyst, carrying out contact reaction on a binary acid monomer, a dihydric alcohol monomer, a component a with a structure as shown in a formula (I), a component b with a structure as shown in a formula (II) and a component c with a structure as shown in a formula (III). The modified copolyester fiber material has good softness and crease resistance, the wearability of a polyester fiber product can be effectively improved, and the diversity and functionality of the polyester material are improved. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of polyester fiber production, and specifically, to a modified copolyester, a preparation method thereof, and a polyester fiber product containing the modified copolyester. Background Art

[0002] Polyester fibers have characteristics such as high strength, high modulus, and wear resistance, and are widely used as textile materials in various fields such as clothing, decoration, and industry. In order to better improve the wearing performance of polyester fibers, a large number of studies on the modification of polyester fibers have been carried out by researchers. Flexible comonomers such as polyethylene glycol, polyether polyol, polytetrahydrofuran, and long-chain diols can be introduced into polyester fibers to endow polyester fibers with properties such as flexibility and hydrophilicity. For example, CN102965761A discloses a mixed fiber obtained by one-step spinning of a hydrophilic copolyester chip spinning solution and a high-shrinkage copolyester chip spinning solution. The hydrophilic copolyester chip is a copolymer formed by terephthalic acid, ethylene glycol, isophthalic acid diol ester-5-sulfonate, polyglycol, and other diols through chemical reactions to achieve comprehensive improvement in various properties such as hydrophilicity, dyeability, gloss, and softness; special comonomers can also be introduced into polyester fibers to endow polyester fibers with special properties such as easy natural degradation and easy dyeing. For example, CN109735920A discloses a preparation method of a soft polyester fiber, which is prepared from a modified copolyester according to the FDY process. The preparation method of the modified copolyester is: uniformly mixing terephthalic acid, propylene glycol, fluorine-containing dibasic acid, and hexanediol with a tert-butyl side group, and then carrying out esterification reaction and polycondensation reaction successively, or a PTT fiber with a high dye uptake rate and a fast natural degradation rate.

[0003] However, in the prior art, when using comonomers to introduce segments to modify polyester fibers, the amorphous region in the polyester polymer will be increased, the regularity of the polymer chain will be reduced, the intermolecular force between polyester molecular chains will be reduced, and thus the wrinkle resistance of polyester products will become worse. Especially in flexible polyester products, it is often difficult to achieve both flexibility and wrinkle resistance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem that it is difficult to achieve both flexibility and wrinkle resistance when using comonomers to modify polyesters in the prior art, and to provide a modified copolyester, a preparation method thereof, and a polyester fiber product. The fiber material of the modified copolyester has good softness and wrinkle resistance, can effectively improve the wearing performance of polyester fiber products, and enhance the diversity and functionality of polyester materials.

[0005] To achieve the above object, in the first aspect of the present invention, a modified copolyester is provided. The modified copolyester contains a structural unit A represented by formula (I), a structural unit B represented by formula (II), and a structural unit C represented by formula (III);

[0006]

[0007] Wherein, R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, m is a positive integer of 3 or more; R I , R II and R III are each independently hydrogen or a C1-C10 alkyl group.

[0008] To solve the common problem that it is difficult to simultaneously have the flexibility and wrinkle resistance of polyester fibers, the inventors of the present invention intended to start from the chemical structure of the polyester polymer chain, deeply explored the structure-activity relationship between the chemical structure of the polyester material and its softening performance and wrinkle resistance performance, and by introducing polyether siloxane groups (structural unit A) and groups containing dynamic covalent chemical bonds (structural unit B and structural unit C) into the polyester polymer chain, utilized the flexible long-chain structure of the polyether siloxane groups to achieve soft modification of the material, and utilized the groups capable of forming dynamic covalent bonds to crosslink the polymer chains in the amorphous region of the polyester to improve the wrinkle resistance of materials such as polyester fibers, thereby effectively improving the appearance, hand feeling, etc. of polyester fiber material products, preparing polyester materials with excellent performance to meet the needs in fields such as clothing and home furnishing, providing new ideas for the development of new functional and high-value polyester materials, effectively increasing the diversity of polyester materials, and expanding the functionality of polyester materials.

[0009] The second aspect of the present invention provides a method for preparing a modified copolyester, the method comprising the following steps: in the presence of a catalyst, contacting a dibasic acid monomer, a diol monomer, component a, component b and component c to carry out reaction I;

[0010] Component a is a compound having the structure shown in formula (I), component b is a compound having the structure shown in formula (II), and component c is a compound having the structure shown in formula (III),

[0011]

[0012] Wherein, R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, m is a positive integer of 3 or more; R I , R II and R III are each independently hydrogen or a C1-C10 alkyl group.

[0013] The third aspect of the present invention provides the use of the above-mentioned modified copolyester and / or the modified copolyester prepared by the above-mentioned method in the preparation of polyester fibers.

[0014] The fourth aspect of the present invention provides a polyester fiber product, which contains the above-mentioned modified copolyester and / or the modified copolyester prepared by the above-mentioned method.

[0015] Through the above technical solution, the modified copolyester provided by the present invention incorporates a flexible segment structural unit A into the polymer chain segment to improve the softness of the polyester material, and incorporates structural units B and C that can form dynamic covalent bonds to enhance the inter-molecular chain forces in the amorphous region of the polyester segment, thereby improving the wrinkle-resistant properties of the polyester fiber. The softness and wrinkle-resistant properties of the modified copolyester are highly stable and not prone to failure, ensuring strength while improving the appearance and feel of the polyester fiber, meeting the needs of clothing, home furnishings and other fields, and providing new ideas for the development of new functional polyester materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the mechanism of ionic bonding during the processing and use of the modified copolyester provided by the present invention. DETAILED DESCRIPTION

[0017] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0018] The first aspect of the present invention provides a modified copolyester, which comprises a structural unit A represented by formula (I), a structural unit B represented by formula (II), and a structural unit C represented by formula (III);

[0019]

[0020] wherein R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, which may be a linear alkyl group or a branched alkyl group, preferably a C1-C4 alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, etc.; m is a positive integer greater than 3, specifically 3, 5, 10, 15, 20, 25, 30 or any integer between the above two values, preferably 10-100; R I 、R II and R III Each is independently hydrogen or a C1-C10 alkyl group, which may be a linear alkyl group or a branched alkyl group, preferably hydrogen or a C1-C4 alkyl group, such as hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, etc.

[0021] Starting from the structure of the polymer chain, the modified copolyester provided by the present invention incorporates polyethersiloxane groups (structural unit A) and groups containing dynamic covalent chemical bonds (structural unit B and structural unit C) into the polyester polymer chain. The flexible long-chain structure of the polyethersiloxane groups is utilized to achieve soft modification of the material, and the dienic structure of structural unit B and the dienophile structure of structural unit C are used to form dynamic covalent bonds, enabling a reversible covalent crosslinking network to be formed between the modified copolyester molecules, increasing the intermolecular force between the molecular chains in the amorphous region, and improving the wrinkle resistance of the polyester fiber. At the same time, when the modified copolyester is processed, the dynamic covalent bonds will dissociate and open in the molten state, without affecting the spinning process of the polyester fiber. The schematic diagram of the mechanism of the covalent bond action during the processing and use of the modified copolyester can be as shown in Figure 1 shown.

[0022] According to the present invention, in order to obtain a modified copolyester with more excellent softness and wrinkle resistance, preferably, the content of the structural unit A in the modified copolyester is 1-15 wt%, the content of the structural unit B is 0.1-3 wt%, and the content of the structural unit C is 0.15-5 wt%.

[0023] More preferably, the content of the structural unit A in the modified copolyester is 3-10.5 wt%, the content of the structural unit B is 0.2-2 wt%, and the content of the structural unit C is 0.2-3 wt%.

[0024] According to the present invention, preferably, the modified copolyester further contains a structural unit D represented by formula (IV) and a structural unit E represented by formula (V);

[0025]

[0026] Ar is a group having a benzene ring, a naphthalene ring or an anthracene ring, preferably a group having a benzene ring; R5 is a C2-C10 alkylene group or a C3-C10 cycloalkylene group, and can be, for example, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, cyclononylene, cyclodecylene, etc.

[0027] According to the present invention, in order to obtain a modified copolyester with more excellent softness and wrinkle resistance, preferably, the content of the structural unit D in the modified copolyester is 65-85 wt%; the content of the structural unit E is 10-25 wt%.

[0028] According to the present invention, in order to obtain a modified copolyester with more excellent softness and wrinkle resistance, preferably, R1, R2, R3 and R4 are the same substituents, more preferably C1-C4 alkyl groups, and further preferably methyl or ethyl; R I , RII 、R III are the same substituents, more preferably hydrogen or C1-C4 alkyl, and still more preferably hydrogen or methyl.

[0029] In the present invention, the structural units and their contents in the polyester can be determined by 1 cooperating H-NMR with elemental content detection; among them, the content of structural unit A can be obtained by first detecting the content of silicon element in the polyester and then converting it through the molecular weight of structural unit A; the content of structural unit B can be obtained by detecting the chemical shift and its integral area of the characteristic hydrogen on the furan ring; the content of structural unit C can be obtained by first detecting the content of nitrogen element in the polyester and then converting it through the molecular weight of structural unit C;

[0030] 1 The specific measuring device and conditions of H-NMR are as follows:

[0031] Model of nuclear magnetic resonance device: Bruker 400MHz nuclear magnetic resonance spectrometer; deuterated solvent: deuterated chloroform, trifluoroacetic acid;

[0032] 1 In the H-NMR spectrum, the contents of methylene and aryl hydrogen are obtained according to the integral values of methylene and aryl hydrogen, and in combination with the contents of methylene, hydrogen on the furan ring and aryl hydrogen in structural unit A, structural unit B and structural unit C, the contents of structural unit D and structural unit E in the polyester are converted.

[0033] The second aspect of the present invention provides a method for preparing a modified copolyester, the method comprising the following steps: in the presence of a catalyst, contacting a dicarboxylic acid monomer, a diol monomer, component a, component b and component c to carry out reaction I;

[0034] Component a is a compound having the structure shown in formula (I), component b is a compound having the structure shown in formula (II), and component c is a compound having the structure shown in formula (III),

[0035]

[0036] wherein, R1, R2, R3 and R4 are each independently C1-C10 alkyl, and m is a positive integer of 3 or more; R I 、R II and R III are each independently hydrogen or C1-C10 alkyl.

[0037] Exemplarily, the structural formula of component a is as shown in formula (VI), component b is 2,5-furandimethanol shown in formula (VII), and component c is one or more of the compound shown in formula (VIII), the anhydride of this compound or the ester of this compound,

[0038]

[0039] Among them, component a with the structural formula shown in formula (VI) is a hydroxy silicone oil, which can have different m values according to different viscosities and different specifications of terminal hydroxy group contents selected, and can be obtained by commercial purchase or self-preparation.

[0040] According to the present invention, preferably, R1, R2, R3 and R4 are the same substituents, more preferably C1-C4 alkyl groups, and further preferably methyl or ethyl groups; R I 、R II 、R III are the same substituents, more preferably hydrogen or C1-C4 alkyl groups, and further preferably hydrogen or methyl groups.

[0041] According to the present invention, in order to obtain a modified copolyester with more excellent flexibility and mechanical properties, preferably, the dicarboxylic acid monomer is one or more of the dicarboxylic acid with the structure shown in formula (IV), the acid anhydride of the dicarboxylic acid, and the ester of the dicarboxylic acid, Ar is a group having a benzene ring, a naphthalene ring or an anthracene ring. The dicarboxylic acid monomer is preferably one or more of aromatic dicarboxylic acids having 8 to C 20 , the acid anhydride of the aromatic dicarboxylic acids having 8 to C 20 , and the ester of the aromatic dicarboxylic acids having 8 to C 20 , more preferably one or more of aromatic dicarboxylic acids having 8 to C 20 . Exemplarily, the dicarboxylic acid monomer is one or more selected from isophthalic acid, terephthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and 3,4'-biphenyldicarboxylic acid, further preferably one or more of terephthalic acid, isophthalic acid and phthalic acid, and even more preferably terephthalic acid.

[0042] According to the present invention, preferably, the diol monomer is a diol having the structure shown in formula (V),

[0043] R5 is a C2-C10 alkylene group or a C3-C10 cycloalkylene group. The diol monomer is preferably one or more of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, cyclohexanediol and norbornanedimethanol, more preferably ethylene glycol and / or butylene glycol, and even more preferably ethylene glycol.

[0044] In the present invention, the dicarboxylic acid monomer, the diol monomer, component a, component b and component c used for preparing the modified copolyester can be respectively commercially available products or self-prepared by existing methods in the prior art, and are easy to synthesize and industrially produce.

[0045] According to the present invention, as described above, preferably, in the obtained modified copolyester, the content of the structural unit A is 1-15 wt%, the content of the structural unit B is 0.1-3 wt%, the content of the structural unit C is 0.15-5 wt%, the content of the structural unit D is 65-85 wt%, and the content of the structural unit E is 10-25 wt%. More preferably, the content of the structural unit A is 3-10.5 wt%, the content of the structural unit B is 0.2-2 wt%, and the content of the structural unit C is 0.2-3 wt%.

[0046] According to the present invention, in order to obtain a modified copolyester with better mechanical properties and wrinkle resistance and improve the efficiency of the polymerization reaction, preferably, the molar ratio of the amount of the dicarboxylic acid monomer to the amount of the diol monomer is 1:1.2-4; more preferably 1:1.5-2.5; based on 100 g of the dicarboxylic acid monomer, the amount of the component a is 1.5-20 g, more preferably 5-15 g; the amount of the component b is 0.2-3 g, more preferably 0.5-1.5 g; the amount of the component c is 0.2-3 g, more preferably 0.5-1.5 g.

[0047] According to the present invention, specifically, the dicarboxylic acid monomer is a dicarboxylic acid having the structure shown in formula (IV), the diol monomer is an aliphatic diol having 2-10 carbon atoms, the component a is a compound shown in formula (VI), the component b is 2,5-furandimethanol shown in formula (VII), and the component c is a compound shown in formula (VIII); at this time, both the component a (belonging to polyether siloxane diol) and the dicarboxylic acid monomer form a structural unit F through transesterification reaction, both the component b and the dicarboxylic acid monomer form a structural unit G through transesterification reaction, both the component c and the diol monomer form a structural unit H through transesterification reaction, and both the dicarboxylic acid monomer and the diol monomer form a structural unit J through transesterification reaction; and they are polymerized to form a modified copolyester.

[0048]

[0049]

[0050] According to the present invention, the modified copolyester can be considered as a linear copolyester containing repeating segments of the structural unit F, repeating segments of the structural unit G, repeating segments of the structural unit H, and repeating segments of the structural unit J; in particular, a linear copolyester composed of repeating segments of the structural unit F, repeating segments of the structural unit G, repeating segments of the structural unit H, and repeating segments of the structural unit J.

[0051] The molecular weight and molecular weight distribution of the modified copolyester are tested by gel permeation chromatography. Preferably, the weight-average molecular weight of the modified copolyester is 18,500 - 25,000 g / mol; the molecular weight distribution index is 1.5 - 2.0.

[0052] According to the present invention, the process of Reaction I is to enable sufficient transesterification and polymerization reactions among the dibasic acid monomer, the diol monomer, Component a, Component b, and Component c. Preferably, the catalyst is an antimony catalyst; at this time, the modified copolyester contains heavy metal elements introduced by the catalyst. Correspondingly, the content of heavy metal elements in the modified copolyester corresponds to the catalyst content.

[0053] According to the present invention, the above preparation method will produce a product of modified copolyester, which contains a large amount of linear copolymer and a small amount of catalyst. Those skilled in the art can understand that the product of modified copolyester is composed of a linear copolyester containing Structural Unit A, Structural Unit B, Structural Unit C, Structural Unit D, and Structural Unit E and the catalyst. Preferably, the content of the catalyst in the product is 0.05 - 0.5 wt%. The content of the catalyst can be obtained by conversion after measuring the content of heavy metal elements (antimony) in the catalyst.

[0054] According to the present invention, preferably, the catalyst is selected from one or more of antimony trioxide, antimony glycolate, and antimony acetate, and more preferably antimony trioxide; the antimony catalyst can be a commercially available product or can be prepared by a conventional method.

[0055] According to the present invention, preferably, based on 100 g of the dibasic acid monomer, the dosage of the catalyst is 0.02 - 0.5 g, and more preferably 0.05 - 0.1 g. The antimony catalyst within this dosage range has a sufficient amount to satisfy the polymerization reaction and promote the copolymerization of the Structural Unit F segment, the Structural Unit G segment, the Structural Unit H segment, and the Structural Unit J segment, and will not introduce excessive metal element content into the product of the modified copolyester.

[0056] According to the present invention, preferably, the process of Reaction I includes: first performing a first-stage reaction under esterification reaction conditions, and then performing a second-stage reaction under polycondensation reaction conditions.

[0057] According to the present invention, preferably, the esterification reaction conditions include: the temperature is 230 - 260 °C, specifically it can be 230 °C, 235 °C, 240 °C, 245 °C, 250 °C, 255 °C, 260 °C, or any value between the above two values; the stirring rate is 130 - 170 rpm, specifically it can be 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, or any value between the above two values; the time is 3 - 4 h, specifically it can be 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, or any value between the above two values; the polycondensation reaction conditions include: the temperature is 250 - 280 °C, specifically it can be 250 °C, 255 °C, 260 °C, 265 °C, 270 °C, 275 °C, 280 °C, or any value between the above two values; the absolute pressure is 80 - 100 Pa, specifically it can be 80 Pa, 85 Pa, 90 Pa, 95 Pa, 100 Pa, or any value between the above two values; the stirring rate is 230 - 270 rpm, specifically it can be 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, or any value between the above two values; the time is 60 - 80 min, specifically it can be 60 min, 65 min, 70 min, 75 min, 80 min, or any value between the above two values.

[0058] In the present invention, the product obtained by reacting the dibasic acid monomer, dibasic alcohol monomer, component a, component b and component c through reaction I is cooled and pelletized to obtain the modified copolyester chips.

[0059] The third aspect of the present invention provides the application of the above-mentioned modified copolyester and / or the modified copolyester prepared by the above-mentioned method in the preparation of polyester fibers.

[0060] The fourth aspect of the present invention provides a polyester fiber product, which contains the above-mentioned modified copolyester and / or the modified copolyester prepared by the above-mentioned method.

[0061] Based on maintaining relatively high mechanical properties, the polyester fiber product provided by the present invention has good softness and wrinkle resistance. The viscosity of the polyester fiber product is 0.6 - 0.85 dL / g, the elongation at break is 15 - 35%, the breaking strength is 2.8 - 4 cN·dtex -1 and the modulus at 0 - 1% is 38 - 56 cN·dtex -1 , and the fiber bundle (48 bundles) is easy to recover after being bent by 90°.

[0062] In the present invention, the method for preparing the polyester fiber product comprises: subjecting the above-mentioned modified copolyester and / or the modified copolyester prepared according to the above-mentioned method to pre-drying and then performing melt spinning. Among them, the melt spinning can be carried out using conventional spinning equipment, such as a screw extruder. Preferably, the temperature of the melt spinning is 270 - 310 °C. Specifically, in the screw extruder, the melt temperature of the polyester screw is set to 270 - 310 °C, and the temperature of the spinning box is set to 270 - 310 °C.

[0063] The present invention will be described in detail below through examples.

[0064] In the following examples, the weight average molecular weight and the molecular weight distribution index were measured by gel permeation chromatography (GPC). Among them, hexafluoroisopropanol (HFIP) was used as the solvent, and the measurement was carried out on a Waters-208 (equipped with a Waters2410 RI detector, a flow rate of 1.5 mL / min, and a temperature of 30 °C) instrument. The molecular weight was calibrated with a monodisperse linear polystyrene standard sample;

[0065] The content of each structural unit in the polyester can be obtained by 1 1H-NMR and elemental determination. The content of structural unit A is obtained by first detecting the content of silicon element in the polyester and then converting it through the molecular weight of structural unit A; the content of structural unit B can be obtained from the chemical shift and integral area of the characteristic hydrogen on the furan ring; the content of structural unit C can be obtained by first detecting the content of nitrogen element in the polyester and then converting it through the molecular weight of structural unit C; 1 The specific measurement device and conditions for 1H-NMR are as follows: Nuclear magnetic resonance device model: Bruker 400 MHz nuclear magnetic resonance spectrometer; Deuterated solvent: Deuterated chloroform, trifluoroacetic acid; 1 In the 1H-NMR spectrum, the content percentage is calculated from the chemical shift and integral area of the methylene group, the hydrogen on the furan ring, and the aryl hydrogen, and in combination with the content of structural unit A, structural unit B, and structural unit C, the content of structural unit D and structural unit E in the polyester is calculated.

[0066] The viscosity was measured by an Ubbelohde viscometer according to the method in "GB17931-2003 Poly(ethylene terephthalate) (PET) resin for bottles". The specific detection process is as follows: Use a type 1B capillary viscometer in ISO 1628-1:1998 The solvent was prepared by mixing phenol and 1,1,2,2-tetrachloroethane in a mass ratio of 60:40. The polyester was dissolved at 110 °C to form a 0.005 g / mL solution. The solution was placed in a water bath at (25 ± 0.02) °C for 20 min and then the measurement was started. Record the time taken for the liquid level to flow between two scales. The maximum error of the three measurement times was controlled within 0.2 s, and the intrinsic viscosity was calculated according to the formula;

[0067] Intrinsic viscosity where c is the concentration of the solution (g / dL), and η r is the relative viscosity, and η r = t / t0, where t is the outflow time of the solution (unit: s), and t0 is the outflow time of the solvent (unit: s).

[0068] The breaking strength and breaking elongation are measured using a single-filament strength tester in accordance with the "GB14337-2008-T Test Method for Tensile Properties of Chemical Fiber Staple Fibers". The specific testing process is as follows: Clamp one end of the fiber corresponding to the modified copolyester with a specified tension clip, place the fiber in the gripper of the instrument, ensure that the fiber elongates along the axis, then conduct a tensile test to obtain the load and elongation value at the moment of specimen fracture, measure the linear density of the fiber, and calculate the tensile breaking strength and breaking elongation; The 0-1% modulus is calculated from the stress-strain curve of the fiber. The specific testing and calculation process is as follows: Take the curve within the range of 0-1% strain in the stress-strain curve and calculate the slope of this section of the curve. The slope value is the 0-1% modulus;

[0069] The detection process for the ease of bending and recovery of the fiber bundle is as follows: Bend a fiber bundle formed by 48 fibers to 90° and hold for 5 s, then release it. Observe the recovery state immediately after release through a microscope to see if it can return to its original position.

[0070] In the following examples, unless otherwise specified, the raw materials and reagents used are all conventional commercially available products.

[0071] Example 1

[0072] Add terephthalic acid (dicarboxylic acid monomer, 100 g), ethylene glycol (diol monomer), (Component a, m = 100, purchased from Shandong Longhui Chemical Co., Ltd., product number 58130-04-4), (i.e., 2,5-furandimethanol, Component b, purchased from Shanghai Macklin Biochemical Co., Ltd., product number 1883-75-6), (i.e., 5 - maleimidobenzene - 1,3 - dicarboxylic acid, component c, purchased from Henan WIT Chemical Technology Co., Ltd., product number 55738 - 70 - 0) and antimony trioxide were added such that the molar ratio of the dibasic acid monomer to the diol monomer was 1:2. The amount of component a was 10 wt% of the weight of the dibasic acid monomer, component b and component c were each 1 wt% of the weight of the dibasic acid monomer, and antimony trioxide was 0.07 wt% of the weight of the dibasic acid monomer. It was heated to 250 °C and the esterification reaction was carried out at a stirring speed of 150 rpm. After reacting for 2 hours, vacuum was applied to make the internal pressure of the reaction kettle reach 90 Pa (absolute pressure), and the material temperature was heated to 270 °C. The reaction was carried out at a constant temperature and pressure at a stirring speed of 250 rpm for 70 min to obtain a copolyester product, which was cooled and pelletized to obtain modified copolyester chips.

[0073] Example 2

[0074] The modified copolyester chips were prepared according to the method of Example 1, except that the amount of component a was replaced with: the amount of component a was 5 wt% of the weight of the dibasic acid monomer.

[0075] Example 3

[0076] The modified copolyester chips were prepared according to the method of Example 1, except that the amount of component a was replaced with: the amount of component a was 15 wt% of the weight of the dibasic acid monomer.

[0077] Example 4

[0078] Isophthalic acid (dibasic acid monomer, 100 g), ethylene glycol (diol monomer), (component a, the same as in Example 1), (component b), (component c) and antimony trioxide were added to the reaction kettle in proportion such that the molar ratio of the dibasic acid monomer to the diol monomer was 1:1.5. The amount of component a was 5 wt% of the weight of the dibasic acid monomer, component b and component c were each 0.5 wt% of the weight of the dibasic acid monomer, and antimony trioxide was 0.05 wt% of the weight of the dibasic acid monomer. It was heated to 230 °C and the esterification reaction was carried out at a stirring speed of 130 rpm. After reacting for 2 hours, vacuum was applied to make the internal pressure of the reaction kettle reach 100 Pa (absolute pressure), and the material temperature was heated to 250 °C. The reaction was carried out at a constant temperature and pressure at a stirring speed of 270 rpm for 60 min to obtain a copolyester product, which was cooled and pelletized to obtain modified copolyester chips.

[0079] Example 5

[0080] Terephthalic acid (dibasic acid monomer, 100 g), butanediol (diol monomer), (component a, the same as in Example 1), (Component b), (Component c) and antimony trioxide, such that the molar ratio of the dibasic acid monomer to the diol monomer is 1:2.5, the amount of component a is 10 wt% of the weight of the dibasic acid monomer, components b and c are respectively 1.5 wt% of the weight of the dibasic acid monomer, and antimony trioxide is 0.1 wt% of the weight of the dibasic acid monomer; heat to 260 °C, carry out an esterification reaction at a stirring speed of 170 rpm, carry out vacuum pumping after reacting for 2 hours, make the internal pressure of the reaction kettle reach 80 Pa (absolute pressure), and heat the material temperature to 280 °C, carry out a constant temperature and constant pressure reaction at a stirring speed of 230 rpm for 80 min to obtain a copolyester product, cool and pelletize to obtain modified copolyester chips.

[0081] Example 6

[0082] Prepare modified copolyester chips according to the method of Example 1, except that component a is replaced with (Component a, m = 150, different from the values in Examples 1-5, purchased from Shandong Longhui Chemical Co., Ltd., product number 58130-04-4).

[0083] Example 7

[0084] Prepare modified copolyester chips according to the method of Example 1, except that component a is replaced with (Component a, m = 180, purchased from Shandong Longhui Chemical Co., Ltd., product number 58130-04-4).

[0085] Example 8

[0086] Prepare modified copolyester chips according to the method of Example 1, except that component c is replaced with (Synthesized by Shanghai Nafu Biotechnology Co., Ltd.).

[0087] Example 9

[0088] Prepare modified copolyester chips according to the method of Example 1, except that the molar ratio of the dibasic acid monomer to the diol monomer is 1:1.2.

[0089] Example 10

[0090] Prepare modified copolyester chips according to the method of Example 1, except that the molar ratio of the dibasic acid monomer to the diol monomer is 1:4.

[0091] Example 11

[0092] Prepare modified copolyester chips according to the method of Example 1, except that components b and c are respectively 3 wt% of the weight of the dibasic acid monomer.

[0093] Example 12

[0094] The modified copolyester chips were prepared according to the method of Example 1, except that components b and c were 0.2 wt% of the weight of the dicarboxylic acid monomer respectively.

[0095] Example 13

[0096] The modified copolyester chips were prepared according to the method of Example 1, except that antimony trioxide was replaced by antimony acetate, and the dosage of antimony acetate was 0.02 wt% of the weight of the dicarboxylic acid monomer.

[0097] Comparative Example 1

[0098] Terephthalic acid (dicarboxylic acid monomer, 100 g), ethylene glycol (diol monomer), (Component a, the same as in Example 1) and antimony trioxide were added to the reaction kettle in proportion, so that the molar ratio of the dicarboxylic acid monomer to the diol monomer was 1:2, the dosage of component a was 10 wt% of the weight of the dicarboxylic acid monomer, and antimony trioxide was 0.07 wt% of the weight of the dicarboxylic acid monomer; it was heated to 250 °C, and the esterification reaction was carried out at a stirring speed of 150 rpm. After reacting for 2 hours, vacuum was pumped to make the internal pressure of the reaction kettle reach 90 Pa (absolute pressure), and the material temperature was heated to 270 °C, and the reaction was carried out at a constant temperature and pressure at a stirring speed of 250 rpm for 70 min to obtain a copolyester product, which was cooled and pelletized to obtain modified copolyester chips.

[0099] Comparative Example 2

[0100] Terephthalic acid (dicarboxylic acid monomer, 100 g), ethylene glycol (diol monomer), (Component b), (Component c) and antimony trioxide were added to the reaction device in proportion, so that the molar ratio of the dicarboxylic acid monomer to the diol monomer was 1:2, components b and c were 1 wt% of the weight of the dicarboxylic acid monomer respectively, and antimony trioxide was 0.07 wt% of the weight of the dicarboxylic acid monomer; it was heated to 250 °C, and the esterification reaction was carried out at a stirring speed of 150 rpm. After reacting for 2 hours, vacuum was pumped to make the internal pressure of the reaction kettle reach 90 Pa (absolute pressure), and the material temperature was heated to 270 °C, and the reaction was carried out at a constant temperature and pressure at a stirring speed of 250 rpm for 70 min to obtain a copolyester product, which was cooled and pelletized to obtain modified copolyester chips.

[0101] Comparative Example 3

[0102] Terephthalic acid (dicarboxylic acid monomer, 100 g), ethylene glycol (diol monomer), (Component a, the same as in Example 1), (Component B), antimony trioxide, such that the molar ratio of the dibasic acid monomer to the diol monomer is 1:2, the amount of Component A is 10 wt% of the weight of the dibasic acid monomer, Component B is 1 wt% of the weight of the dibasic acid monomer, and antimony trioxide is 0.07 wt% of the weight of the dibasic acid monomer; heated to 250 °C, the esterification reaction is carried out at a stirring speed of 150 rpm. After reacting for 2 hours, vacuum is drawn to make the internal pressure of the reaction kettle reach 90 Pa (absolute pressure), and the material temperature is heated to 270 °C, and the reaction is carried out at a constant temperature and pressure of 250 rpm for 70 min to obtain a copolyester product, which is cooled and pelletized to obtain modified copolyester chips.

[0103] Test Example 1

[0104] The yields, catalyst contents, weight-average molecular weights, and molecular weight distribution indices of the modified copolyester chips prepared in Examples 1 - 13 and Comparative Examples 1 - 3 were measured, and the results are shown in Table 1. The contents of the chain segment structures of each polymer structural unit in the modified copolyester were measured, and the results are shown in Table 2.

[0105] Table 1

[0106]

[0107]

[0108] Table 2

[0109]

[0110] Test Example 2

[0111] Taking a commercially available conventional polyester as a reference, the viscosities, elongation at break, breaking strength, and initial modulus of the modified copolyesters prepared in Examples 1 - 13 and Comparative Examples 1 - 3 and the conventional polyester were measured, and the results are shown in Table 3.

[0112] The modified copolyester fibers were prepared using the modified copolyester chips prepared in Examples 1 - 13 and Comparative Examples 1 - 3: the modified copolyester chips were pre-crystallized and dried, and the dried modified copolyester chips were added to a screw extruder for melt spinning. The melt temperature of the polyester screw was 290 °C, and the spinning box temperature was 290 °C to obtain modified copolyester fibers.

[0113] The ease of recovery of the modified copolyester fibers and the conventional polyester fibers corresponding to Examples 1 - 13 and Comparative Examples 1 - 3 after the tow was bent 90° was measured, and the results are shown in Table 3.

[0114] Table 3

[0115]

[0116] As can be seen from Table 3, compared with conventional polyesters, the modified copolyester fibers prepared in Examples 1-13 have obvious changes in performance parameters such as viscosity, elongation at break, breaking strength, and initial modulus, proving that the addition of the modifying monomer has an important impact on the polyester polymer chain and its properties.

[0117] From Example 1 and Comparative Example 1, it can be seen that if only component a, the hydroxyl silicone oil flexible monomer, is added to the polymerization system, compared with conventional polyester fibers, the breaking strength and initial modulus of the obtained modified copolyester fibers both decrease, and the elongation at break increases, but it is difficult for the fibers to recover after being bent.

[0118] From Example 1 and Comparative Example 2, it can be seen that if component a (the hydroxyl silicone oil flexible monomer) is not added to the polymerization system and only components b and c (the diene monomer and the dienophile monomer) are added, since the modifying monomer is incorporated into the polyester molecular chain, the regularity of the polymer chain is destroyed, the crystallinity decreases, the breaking strength decreases, the elongation at break increases, and it is easy to recover after being bent. However, the change in the initial modulus of this modified copolyester fiber is not significant, that is, the increase in softness is not significant enough.

[0119] From Example 1 and Comparative Example 3, it can be seen that if only component a (the soft monomer hydroxyl silicone oil) and component b, the diene monomer (2,5-furandimethanol), are added to the polymerization system, due to the copolymerization introduction of the modifying monomer, the regularity of the polyester molecular chain decreases, the crystallinity decreases, the breaking strength and the initial modulus decrease. Since dynamic covalent bonds cannot be formed in the fibers, the intermolecular force in the amorphous region is low, and the wrinkle resistance of the fibers is poor, and it is not easy for the fibers to recover after being bent.

[0120] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A modified copolyester, characterized in that, The modified copolyester contains structural unit A represented by formula (I), structural unit B represented by formula (II), and structural unit C represented by formula (III); Wherein, R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, m is a positive integer of 3 or more; R I , R II and R III are each independently hydrogen or a C1-C10 alkyl group.

2. The modified copolyester according to claim 1, characterized in that, In the modified copolyester, the content of the structural unit A is 1-15 wt%, the content of the structural unit B is 0.1-3 wt%, and the content of the structural unit C is 0.15-5 wt%; Preferably, in the modified copolyester, the content of the structural unit A is 3-10.5 wt%, the content of the structural unit B is 0.2-2 wt%, and the content of the structural unit C is 0.2-3 wt%.

3. The modified copolyester according to claim 1 or 2, characterized in that, The modified copolyester further contains structural unit D represented by formula (IV) and structural unit E represented by formula (V); Wherein, Ar is a group having a benzene ring, a naphthalene ring or an anthracene ring; R5 is a C2-C10 alkylene group or a C3-C10 cycloalkylene group; Preferably, in the modified copolyester, the content of the structural unit D is 65-85 wt%; the content of the structural unit E is 10-25 wt%.

4. The modified copolyester according to claim 3, characterized in that, R1, R2, R3 and R4 are the same substituents, preferably C1-C4 alkyl groups, more preferably methyl or ethyl; R I 、R II and R III are the same substituents, preferably hydrogen or C1-C4 alkyl, more preferably hydrogen or methyl; Ar is a group having a benzene ring.

5. A method for preparing a modified copolyester, characterized in that, The method includes the following steps: in the presence of a catalyst, contacting a dicarboxylic acid monomer, a diol monomer, component a, component b and component c to carry out reaction I; The component a is a compound having the structure shown in formula (I), the component b is a compound having the structure shown in formula (II), and the component c is a compound having the structure shown in formula (III), Wherein, R1, R2, R3 and R4 are each independently a C1-C10 alkyl group, m is a positive integer of 3 or more; R I , R II and R III are each independently hydrogen or a C1-C10 alkyl group.

6. The preparation method according to claim 5, characterized in that, R1, R2, R3 and R4 are the same substituents, preferably C1-C4 alkyl groups, more preferably methyl or ethyl; R I 、R II and R III are the same substituents, preferably hydrogen or C1-C4 alkyl, more preferably hydrogen or methyl; Preferably, the dibasic acid monomer is one or more of a dibasic acid having the structure shown in formula (IV), an anhydride of the dibasic acid, and an ester of the dibasic acid. Ar is a group having a benzene ring, a naphthalene ring or an anthracene ring; more preferably, it is one or more selected from isophthalic acid, terephthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid and 3,4'-biphenyldicarboxylic acid; further preferably, it is one or more selected from terephthalic acid, isophthalic acid and phthalic acid. Preferably, the diol monomer is a diol having the structure shown in formula (V), R5 is one or more of C2-C10 alkylene groups and C3-C10 cycloalkylene groups; more preferably, it is one or more selected from ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, and cyclohexanediol, and still more preferably ethylene glycol and / or butylene glycol.

7. The preparation method according to claim 5 or 6, characterized in that The molar ratio of the dicarboxylic acid monomer to the diol monomer is 1:1.2-4; preferably 1:1.5-2.5; Preferably, based on 100 g of the dicarboxylic acid monomer, the amount of the component a is 1.5-20 g, preferably 5-15 g; the amount of the component b is 0.2-3 g, more preferably 0.5-1.5 g; the amount of the component c is 0.2-3 g, more preferably 0.5-1.5 g; the amount of the catalyst is 0.02-0.5 g, more preferably 0.05-0.1 g; Preferably, the catalyst is an antimony catalyst, more preferably one or more selected from antimony trioxide, antimony glycolate and antimony acetate, and further preferably antimony trioxide.

8. The preparation method according to claim 5 or 6, characterized in that, The process of the reaction I includes: first carrying out a first-stage reaction under esterification reaction conditions, and then carrying out a second-stage reaction under polycondensation reaction conditions; Preferably, the esterification reaction conditions include: temperature is 230-260 °C, stirring rate is 130-170 rpm, and time is 3-4 h; Preferably, the polycondensation reaction conditions include: temperature is 250-280 °C, absolute pressure is 80-100 Pa, stirring rate is 230-270 rpm, and time is 60-80 min.

9. Use of the modified copolyester according to any one of claims 1 to 4 and / or the modified copolyester prepared by the method according to any one of claims 5 to 8 in the preparation of polyester fibers.

10. A polyester fiber product, characterized in that, The polyester fiber product contains the modified copolyester according to any one of claims 1 to 4 and / or the modified copolyester prepared by the method according to any one of claims 5 to 8; Preferably, the viscosity of the polyester fiber product is 0.6-0.85 dL / g, the elongation at break is 25-35%, and the breaking strength is 2.8-4 cN·dtex -1 and the modulus at 0-1% is 38-56 cN·dtex -1 .

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