Soft and anti-wrinkle polyester fiber and preparation method thereof

Abstract

The invention provides a soft and anti-wrinkle polyester fiber and a preparation method thereof, a first monomer and a second monomer are mixed for an esterification reaction, a third monomer is added for a condensation polymerization reaction, a copolymer is obtained after the condensation polymerization is finished, the copolymer is sliced, the first monomer is terephthalic acid, the second monomer is ethylene glycol, and the third monomer is long-chain alkyl diamine; and then carrying out melt spinning on the obtained modified polyester master batch to obtain the soft and anti-wrinkle polyester fiber. The dibasic acid, the dihydric alcohol and the long-chain alkyl diamine are copolymerized, hydrogen-bond interaction among molecular chains is provided through amido bonds formed in the polymerization process, and the molecular chains are tightly connected together under the action of a large number of hydrogen bonds, so that the toughness and the anti-wrinkle performance of the material are improved; meanwhile, long-chain alkyl in the modified monomer contains more methylene flexible chain segments, and after the long-chain alkyl is introduced into a PET macromolecular main chain, a macromolecular chain is easier to move, so that a polyester fiber product with soft touch and good wrinkle resistance is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of polyester fibers, and in particular to a soft and wrinkle-resistant polyester fiber and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate fiber (PET fiber) is the synthetic fiber with the largest consumption. The biggest advantage of its clothing products is that it has good wrinkle resistance and shape retention, and has high strength and elastic recovery ability. Polyester fiber fabrics are widely popular among textile materials due to their excellent wrinkle resistance and shape retention, and their fabrics are strong and durable, wrinkle-resistant, iron-free, and non-sticky. However, because there are rigid benzene rings and flexible methylene groups in the PET molecular chain, the rigid chain is dominant, and the macromolecular chain is arranged regularly and has a high degree of crystallinity, resulting in a harder feel of polyester fiber, which affects its comfort, thereby limiting its application in a wider range. In view of the above problems, it is of great significance to develop a fiber fabric that is both soft and wrinkle-resistant.

[0003] In order to improve its wearing comfort, in the preparation technology of super soft polyester fiber, the patent with publication number CN103774267A discloses a method for preparing super soft polyester fiber by esterification polycondensation. First, a mixed polyol (one or more of ethylene glycol, propylene glycol, butanediol or pentanediol, one or more of polyhydroxy alcohol sorbitol, pentaerythritol or xylitol and polyethylene glycol are configured into a mixed polyol according to different molar ratios) is esterified with a dibasic acid, and then a polyhydroxy flexible polyester is prepared by polycondensation. The polyhydroxy active sites in the fiber and the ether bonds in the flexible chain polyethylene glycol can give the fiber super high softness and good dyeing performance. However, although this method improves its softness, this modification often sacrifices the wrinkle resistance of the fiber.

[0004] The modified copolyester in the patent with publication number CN117468116A is prepared by melt blending of lubricating functional masterbatch and flexible polyester chips. The lubricating functional masterbatch is prepared by copolymerization of terephthalic acid, ethylene glycol and polydimethylsiloxane, and the flexible polyester chips are prepared by copolymerization of terephthalic acid, ethylene glycol and a third monomer (flexible segments such as polyethylene glycol and polytetrahydrofuran). This method introduces long-chain polydimethylsiloxane, and uses its micro-chain extension reaction to optimize the interface effect, improve the compatibility of the lubricating functional masterbatch and the flexible polyester chips, and solve the problem of melt blending compatibility of the two. Although the modified copolyester achieves a softening effect, its process must go through the process of first copolymerization and then blending, which is cumbersome and complicated, with a large workload, and there is also a compatibility problem.

[0005] In the patent with publication number CN117661328A, a polyether-modified polyester finishing agent is used to finish polyester fabrics. Terephthalic acid and polyethylene glycol are dried and dehydrated, and added into a reactor with a PEPA-piperazine diol compound to obtain a polyether-modified polyester finishing agent, which is dissolved in water to prepare a finishing liquid, and then the polyester fabric is subjected to two immersions and two rollings to obtain a hydrophilic and wrinkle-resistant polyester fabric. The finishing agent contains a hydrophilic polyether segment that firmly forms a hydrophilic film layer on the surface of the fabric. This improves the hydrophilic moisture permeability and wearing comfort of the fabric. At the same time, the polyether-modified polyester finishing agent has good softness and smoothness, which can improve the softness and wrinkle resistance of the polyester fabric. However, the durability of the surface modification is extremely poor. During the wearing process, the finishing agent on the surface of the fabric is easily shed due to external factors, and the components are easily analyzed.

[0006] Generally speaking, polyether modification is an effective means to improve the softness of materials. However, although the introduction of flexible groups improves ductility, it also leads to a decrease in fiber strength. The flexible chain segments will destroy the structural regularity of the polyester polymer chain. The flexibility of the macromolecules increases, resulting in better flexibility and plasticity of the modified polyester, making the modified polyester more susceptible to deformation, resulting in a decrease in its anti-wrinkle performance. Summary of the invention

[0007] The purpose of the present application is to provide a soft and wrinkle-resistant polyester fiber and a preparation method thereof. The preparation method utilizes dibasic acid, diol and long-chain alkyl diamine for copolymerization, and provides hydrogen bonding between molecular chains through the amide bonds formed during the polymerization process, thereby enhancing the interaction between molecular chains. The molecular chains are tightly connected to each other under the action of a large number of hydrogen bonds, which is an effective method for improving the toughness and wrinkle resistance of the material. At the same time, the long-chain alkyl in the modified monomer contains a large number of methylene flexible chain segments. After the methylene flexible chain segments are introduced into the main chain of the PET macromolecule, the macromolecule chain is more likely to move. Therefore, the relative stiffness of the modified PET fiber is lower than that of the PET fiber, thereby ensuring the necessary softness of the fiber, and preparing a polyester fiber product having a soft touch and maintaining good wrinkle resistance.

[0008] In a first aspect, the present invention provides a method for preparing a soft and wrinkle-resistant polyester fiber, comprising the following steps:

[0009] S1, adding a first monomer and a second monomer into a reaction kettle for esterification reaction; the reaction temperature is 240-260° C., the reaction time is 2-4 hours, and when the water output of the esterification reaction reaches 90% of the theoretical water output, the reaction requirement is met, and the esterification reaction is stopped; the first monomer is terephthalic acid, and the second monomer is ethylene glycol;

[0010] S2, after the esterification is completed, a third monomer is added, and a polycondensation reaction is carried out after a pre-reaction of 0.5 to 1 hour under normal pressure, and the obtained copolymer is pelletized to obtain a modified polyester masterbatch; the third monomer is a long-chain alkyl diamine; the general structural formula of the third monomer is NH2CH2(CH2) m CH2NH2, wherein m is an integer from 4 to 10;

[0011] S3, melt-spinning the polyester masterbatch obtained in step S2 to obtain soft and wrinkle-resistant polyester fibers.

[0012] Preferably, in step S2, the amount of the third monomer added is 2-10% of the molar amount of the first monomer.

[0013] Preferably, in step S1, the molar ratio of the first monomer to the second monomer is 1:(1-1.5).

[0014] Preferably, in step S1, the catalyst added to the esterification reaction is Sb2O3, and the amount of the catalyst added is 400-600 ppm.

[0015] Preferably, in step S2, the specific process of the polycondensation reaction is: first, slowly evacuate to 80-100 Pa within 1-2 hours for pre-polycondensation treatment, then heat the system to 260-280° C., and continue the reaction for 1-2 hours.

[0016] Preferably, m is an integer of 6-10.

[0017] Preferably, the added amount of the third monomer is 4-6% of the molar amount of the first monomer.

[0018] In the second aspect, an embodiment of the present application provides a soft and wrinkle-resistant polyester fiber, which is prepared by the preparation method described in the aforementioned technical scheme. The warp softness of the fabric woven with the soft and wrinkle-resistant polyester fiber reaches 1177.5 mN, and the warp wrinkle recovery angle reaches 98°.

[0019] The beneficial effects of the present invention are:

[0020] 1. The preparation method of the soft and wrinkle-resistant polyester fiber provided by the present invention realizes the preparation of soft and wrinkle-resistant polyester fiber fabric through the synergistic effect of long-chain alkyl and hydrogen bonding. Specifically, the present invention utilizes dibasic acid, diol and long-chain alkyl diamine for copolymerization, and provides hydrogen bonding between molecular chains through the amide bond formed during the polymerization process, thereby enhancing the interaction between molecular chains. The molecular chains are tightly connected to each other under the action of a large number of hydrogen bonds, which is an effective method for improving the toughness and wrinkle resistance of the material; at the same time, the long-chain alkyl in the modified monomer contains more methylene flexible chain segments, and after being introduced into the main chain of the PET macromolecule, the macromolecule chain is more likely to move, so the relative stiffness of the modified PET fiber is lower than that of the PET fiber, which ensures the necessary softness of the fiber, and can prepare a polyester fiber product with both soft touch and good wrinkle resistance.

[0021] 2. The production process of the functional polyester chips of the present invention matches the traditional polyester production process, does not require the modification of existing equipment, has a simple preparation process, and has the potential for industrial production;

[0022] 3. The fiber and fabric prepared by the present invention have both softness and wrinkle resistance, and can improve the hydrophilicity of the fiber and fabric, which is of great help to the post-treatment dyeing process.

[0023] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 The synthetic route of the modified polyester of the present invention is shown in FIG.

[0026] Figure 2 The actual picture of the modified polyester fiber prepared by the present invention; wherein (a) PET, (b) PET-PEG5, (c) PET-PER 0.1 (d) PET-PEG5-PER 0.1 , (e) PET-DDA4, (f) PET-DDA6.

[0027] Figure 3The actual picture of the fabric woven by the modified polyester fiber prepared in the present invention; wherein (A) PET, (B) PET-PEG5, (C) PET-PER 0.1 , (D) PET-PEG5-PER 0.1 , (E)PET-DDA4, (F)PET-DDA6.

[0028] Figure 4 The contact angle diagram of the modified copolyester slice prepared by the present invention; wherein (a) PET, (b) PET-PEG5, (c) PET-PER 0.1 (d) PET-PEG5-PER 0.1 , (e) PET-DDA4, (f) PET-DDA6. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] The present invention provides a method for preparing soft and wrinkle-resistant polyester fiber, comprising the following steps:

[0034] S1, adding a first monomer and a second monomer into a reaction kettle for esterification reaction; the reaction temperature is 240-260° C., the reaction time is 2-4 hours, and when the water output of the esterification reaction reaches 90% of the theoretical water output, the reaction requirement is met, and the esterification reaction is stopped; the first monomer is terephthalic acid, and the second monomer is ethylene glycol;

[0035] Specifically, an esterification process is adopted, with terephthalic acid (PTA) and ethylene glycol (EG) as the first monomer and the second monomer, and a molar ratio of the first monomer to the second monomer of 1: (1 to 1.5), which are put into a polymerization reactor, and 400 to 600 ppm Sb2O3 is added as a catalyst to carry out an esterification reaction. The reaction temperature is 240 to 260°C, and the reaction time is 2 to 4 hours. When the water output of the esterification reaction reaches 90% of the theoretical water output, the reaction requirement is met and the esterification reaction is stopped.

[0036] S2, after the esterification is completed, a third monomer is added, and a polycondensation reaction is carried out after a pre-reaction of 0.5 to 1 hour under normal pressure, and the obtained copolymer is pelletized to obtain a modified polyester masterbatch; the third monomer is a long-chain alkyl diamine; the general structural formula of the third monomer is NH2CH2(CH2) m CH2NH2, wherein m is an integer from 4 to 10;

[0037] Specifically, after the esterification reaction stops, the third monomer is added, and the reaction is carried out at normal pressure for 0.5 to 1 hour to make the reactants uniformly mixed, and then the polycondensation stage is entered. The amount of the third monomer added is 2 to 10% of the molar amount of the first monomer.

[0038] First, a pre-condensation treatment is performed, and the vacuum is slowly pumped to 80-100 Pa within 1-2 hours, and the pre-condensation is completed. Then, a polycondensation reaction is performed, and the system is heated to 260-280° C. and the reaction is continued for 1-2 hours.

[0039] When the stirring power reaches a certain value, that is, when the viscosity reaches the requirement for spinning, the reaction ends, the material is discharged from the bottom of the reactor and drawn out in cold water and then pelletized to obtain modified polyester masterbatch.

[0040] In the present invention, the long-chain alkyl diamine monomer provides both a flexible chain segment and introduces abundant amine groups, and the amine groups form amide bonds in the reaction, thereby providing abundant hydrogen bonding in the polyester molecular chain, and the high-density network hydrogen bonding structure can improve the mechanical properties of the polyester material. Therefore, the long-chain alkyl diamine modified polyester fiber fabric has good softness and greatly improves the wrinkle resistance of the fiber fabric.

[0041] S3, melt-spinning the polyester masterbatch obtained in step S2 to obtain soft and wrinkle-resistant polyester fibers.

[0042] The present invention also provides a soft and wrinkle-resistant polyester fiber, which is prepared by the above-mentioned preparation method. The soft and wrinkle-resistant polyester fiber has both softness and wrinkle resistance, and can improve the hydrophilicity of the fiber and fabric, which is of great help to the post-treatment dyeing process.

[0043] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0044] Example 1

[0045] This embodiment provides a method for preparing a soft and wrinkle-resistant polyester fiber, comprising the following steps:

[0046] S1, using the esterification process, with terephthalic acid (PTA) and ethylene glycol (EG) as the first monomer and the second monomer, according to the molar ratio of the first monomer to the second monomer of 1:1.3, put into a polymerization reactor, add 500ppm Sb2O3 as a catalyst to carry out esterification reaction, the reaction temperature is 240℃, the reaction time is 3h, when the water output of the esterification reaction reaches 90% of the theoretical water output, the reaction requirement is met, and the esterification reaction is stopped;

[0047] S2, after the esterification reaction stops, the third monomer, decanediamine (DDA), is added, and the pre-reaction is carried out at normal pressure for 0.5 hours to make the reactants uniformly mixed, and then the polycondensation stage is entered. The amount of the third monomer decanediamine added is 4% of the molar amount of the first monomer. The obtained copolymer is PET-DDAn, wherein n represents the molar part of the DDA structural unit per 100 moles of PET repeating units, that is, DDA / PET=n / 100.

[0048] First, a pre-condensation treatment was performed, and the vacuum was slowly evacuated to 80-100 Pa within 1.5 hours, and the pre-condensation was completed. Then, a polycondensation reaction was performed, and the system was heated to 280° C. and the reaction was continued for 1.5 hours.

[0049] When the stirring power reaches a certain value, that is, when the viscosity reaches the requirement for spinning, the reaction ends, the material is discharged from the bottom of the reactor and drawn out in cold water and then pelletized to obtain modified polyester masterbatch.

[0050] S3, melt-spinning the polyester masterbatch obtained in step S2 to obtain soft and wrinkle-resistant polyester fibers.

[0051] The modified PET chips were dried in a JM-500QDZGX vacuum drum drying oven until the moisture content was less than 0.01%, and then melt-spun by a spinning machine to obtain undrawn yarn (UDY), which was then drawn by different multiples and slightly twisted to obtain drawn yarn (DT).

[0052] The spinning and drawing process is: winding speed is 1200m / min, the temperature of hot roller 1 is 60℃, and the temperature of hot roller 2 is 100℃. The modified polyester chips are melt-spun to obtain DT yarn, which is a bundle of 36 single yarns. The actual picture is as follows Figure 2 As shown. Then it is twisted on a twisting machine, and then woven into a sample fabric on a sample loom. The warp yarn of the fabric is two strands and the weft yarn is one strand. The resulting fabric is as shown Figure 3 shown.

[0053] Comparative Example 1

[0054] This comparative example provides a method for preparing a soft and wrinkle-resistant polyester fiber. Compared with Example 1, the only difference is that the third monomer decanediamine is replaced by polyethylene glycol (PEG), and the added amount thereof is 5wt% of the mass of the first monomer terephthalic acid; other experimental parameters and conditions are basically the same as those in Example 1 and will not be repeated here.

[0055] Comparative Example 2

[0056] This comparative example provides a method for preparing a soft and wrinkle-resistant polyester fiber. Compared with Example 1, the only difference is that the third monomer decanediamine is replaced by pentaerythritol (PER), and the added amount thereof is 0.1wt% of the mass of the first monomer terephthalic acid; other experimental parameters and conditions are basically the same as those in Example 1 and are not repeated here.

[0057] Comparative Example 3

[0058] This comparative example provides a method for preparing a soft and wrinkle-resistant polyester fiber. Compared with Example 1, the difference is that two monomers (a third monomer polyethylene glycol (PEG) and a fourth monomer pentaerythritol (PER)) are added in step S2, the addition amount of the third monomer polyethylene glycol is 5wt% of the mass of terephthalic acid, and the addition amount of the fourth monomer pentaerythritol is 0.1wt% of the mass of terephthalic acid; other experimental parameters and conditions are basically the same as those in Example 1 and are not repeated here.

[0059] Examples 2-7 and Comparative Examples 4-6

[0060] Compared with Example 1, the main difference is that the type of the third monomer, the amount of the third monomer added, and the molar ratio of the first monomer to the second monomer are changed, and other experimental parameters and conditions are basically the same as those in Example 1, which will not be repeated here. The details are shown in the following table.

[0061]

[0062]

[0063] Experiments show that when the molar ratio of the first monomer to the second monomer is less than 1:1.5, the second monomer ethylene glycol EG content will be too much, which will cause the ethylene glycol to undergo a self-condensation reaction to form diethylene glycol. If the diethylene glycol content is too high, the melting point of the polyester will decrease, affecting the applicable scope of the product. When the molar ratio of the first monomer to the second monomer is within the range of 1: (1 to 1.5), it will not have a significant impact on the mechanical properties and related properties of the polyester, and it will still meet conventional applications.

[0064] When the molar ratio of the first monomer to the second monomer is greater than 1:1, the content of the first monomer terephthalic acid PTA will be relatively excessive, which will lead to incomplete PTA reaction during the esterification process, and the excess PTA during the polycondensation process will cause the polyester macromolecules to condense and then depolymerize, repeating the cycle, and finally causing the polyester to fail to polycondense successfully.

[0065] When the amount of the third monomer added is greater than 10% of the molar amount of the first monomer, the yellowness of the copolyester will be too large as the amount of DDA added increases, affecting its dyeing properties. Although the softness of the fiber fabric spun by the modified copolyester is improved, the application range of the copolyester products will also be limited.

[0066] When the amount of the third monomer added is less than 2% of the molar amount of the first monomer, since the amount of the third monomer added is too small, the effect of a small amount of hydrogen bonding on the softness and wrinkle resistance of the copolyester is not very obvious.

[0067] The main differences between Example 1 and Comparative Examples 1-3 are summarized in the following table:

[0068]

[0069] According to GB / T41567-2022, the softness test was carried out on a fabric softness tester. Five representative specimens with a size of (100±2) mm×(100±2) mm were taken parallel to the warp (vertical) direction and the weft (transverse) direction. The warp and weft directions were tested 5 times each, and the average value was taken.

[0070] The anti-wrinkle performance test was carried out on the YG541E fully automatic laser fabric wrinkle elasticity tester according to GB / T3819. Convex samples were taken in the warp and weft directions of the fabric sample, folded in half on the front side, and tested 5 times in the warp and weft directions respectively, and then the average value was taken.

[0071] The modified polyester prepared in Examples 1-8 and Comparative Examples 1-3 was woven into a sample fabric on a sample loom, wherein two warp yarns and one weft yarn were used. The fabrics obtained in Example 1, Example 3 and Comparative Examples 1-3 are as follows: Figure 3 shown.

[0072] The fabric was tested for softness and wrinkle resistance. The specific data are shown in the following table.

[0073] sample Warp softness / mN Warp wrinkle recovery angle / ° Control PET 1389.1 89.1 Example 1 <![CDATA[PET-DDA4]]> 1177.5 98.0 Example 2 <![CDATA[PET-DDA2]]> 1298.4 90.0 Example 3 <![CDATA[PET-DDA6]]> 1201.0 99.6 Example 4 <![CDATA[PET-DDA8]]> 1139.8 101.7 Example 5 <![CDATA[PET-DDA 10 ]]> 1109.2 104.1 Example 6 <![CDATA[PET-A66]]> 1249.3 100.4 Example 7 <![CDATA[PET-A126]]> 1107.7 98.1 Comparative Example 1 <![CDATA[PET-PEG5]]> 860.6 88.5 Comparative Example 2 <![CDATA[PET-PER 0.1 ]]> 1278.7 90.0 Comparative Example 3 <![CDATA[PET-PEG5-PER 0.1 ]]> 1105.8 92.4

[0074] Note: PET-A66 and PET-A126 indicate that the third monomer is hexamethylenediamine and dodecylamine and the added amount is 6% of the molar amount of the first monomer.

[0075] From the table above, we can see that pure PET itself has good wrinkle resistance, but its softness value is the highest, so its softness is poor. After the introduction of soft segment polyethylene glycol or pentaerythritol, its softness is improved, but the wrinkle resistance does not change much. When the long-chain alkyl diamine with both soft segments and amide bonds is introduced, the softness is improved and the wrinkle recovery angle is significantly increased, and the wrinkle resistance is significantly improved. And the addition of a single long-chain alkyl diamine has better uniformity than adding polyethylene glycol and pentaerythritol.

[0076] Specifically, compared with the control sample (pure polyester fiber), the softness and wrinkle resistance of the fabric prepared in Example 1 are significantly improved, and it has both softness and wrinkle resistance. This is because: the long-chain alkyl diamine monomer not only provides a flexible segment but also introduces abundant amine groups, and the amine groups form amide bonds in the reaction, thereby providing abundant hydrogen bonding in the polyester molecular chain. The high-density network hydrogen bond structure can improve the mechanical properties of the polyester material. Therefore, the long-chain alkyl diamine modified polyester fiber fabric has good softness and greatly improves the wrinkle resistance of its fiber fabric. Examples 2 to 5 are different amounts of the third monomer added, and the fabric can obtain different degrees of softness and wrinkle resistance. The third monomer in Examples 6 and 7 is hexamethylenediamine and dodecylamine, and the addition amount is 6% of the molar amount of the first monomer. It is different from the long-chain alkyl in the third monomer of Example 3. The softness and wrinkle resistance of its fiber fabric can be controlled by adjusting the addition amount, and the performance equivalent to that of Example 3 can also be obtained.

[0077] Comparing the data of the control sample (pure polyester fiber) with that of comparative example 1, it can be seen that because the pure polyester fiber fabric itself has good wrinkle resistance but poor softness, the introduction of polyethylene glycol soft chain segments in comparative example 1 improves the softness of the polyester fiber fabric, but also causes its wrinkle resistance to decrease due to the addition of the soft chain segments.

[0078] In Comparative Example 2, pentaerythritol, as one of the raw materials, participates in the polymerization reaction with terephthalic acid (PTA) and ethylene glycol (EG) to form a polyester chain. These chain links are connected by ester groups to form a three-dimensional physical cross-linked network structure, which gives polyester its unique physical properties, such as strength and toughness. It was found through preliminary experimental exploration that it is easy to explode and be unable to spin during the reaction, so it is not advisable to add more. Because the addition of pentaerythritol forms a physical cross-linked network structure in the polyester molecular chain, the modified polyester has good toughness, but the wrinkle resistance of its fiber fabric has not changed significantly. Compared with the wrinkle resistance of the fabric prepared from pure polyester fiber, the wrinkle resistance has decreased.

[0079] In Comparative Example 3, two monomers were added, the third monomer polyethylene glycol and the fourth monomer pentaerythritol. The polyethylene glycol brought a flexible chain segment and the pentaerythritol brought a physically cross-linked network structure, which worked together to improve the softness and wrinkle resistance of the modified polyester fiber fabric. From the test data, it can be seen that its softness and wrinkle recovery have been improved to a certain extent, but due to the explosion phenomenon of pentaerythritol, its addition amount is limited, and the anti-wrinkle performance is not improved much.

[0080] It can be seen that compared with Example 1 in which only one monomer is added, the softness of the fabric prepared from the modified polyester fiber obtained in Comparative Example 3 is close to that of Example 1, but the wrinkle recovery is far worse than that of Example 1, and the technical effect of Example 1 of both wrinkle resistance and softness cannot be achieved.

[0081] In addition, the modified polyester and its fiber fabric prepared by this method have also been improved in hydrophilicity to a certain extent. Whether it is the introduction of polyethylene glycol, pentaerythritol or long-chain alkyl diamine, it provides abundant hydrophilic groups for the modified copolyester, improves its hydrophilic properties to a certain extent, and provides great help for the dyeing properties of its fiber fabric.

[0082] Specifically, pure PET masterbatch and modified polyester masterbatch were pressed into tablets and tested using a surface contact angle tester at 20°C and 65% humidity. The amount of water added was 2μL, the drop speed was 1μL / s, and the static contact angle test was completed within 10s after contact. The average deviation did not exceed ±2°. This was repeated 10 times and the average value was taken. The test results are shown in the following table.

[0083] like Figure 4 As shown, a, b, c, d, e, and f are PET (control sample), PET-PEG5 (comparative example 1), PET-PER 0.1 (Comparative Example 2), PET-PEG5-PER 0.1 The contact angles of polyester chips of PET-DDA4 (Comparative Example 3), PET-DDA4 (Example 1), and PET-DDA6 (Example 3).

[0084] sample Contact angle / ° Control PET 82.4° Example 1 <![CDATA[PET-DDA4]]> 82.4° Example 2 <![CDATA[PET-DDA2]]> 84.6° Example 3 <![CDATA[PET-DDA6]]> 76.3° Example 4 <![CDATA[PET-DDA 10 ]]> 75.2° Example 5 <![CDATA[PET-DDA 12 ]]> 74.9° Comparative Example 1 <![CDATA[PET-PEG5]]> 77.1° Comparative Example 2 <![CDATA[PET-PER 0.1 ]]> 82.3° Comparative Example 3 <![CDATA[PET-PEG5-PER 0.1 ]]> 68.9°

[0085] The contact angle of unmodified pure PET polyester chips is 82.4°, which is determined by the inherent properties of PET. The contact angles of polyesters modified by different monomers are lowered. After the introduction of 5wt% polyethylene glycol, the contact angle is reduced to 77.1°, and after the introduction of 5wt% PEG and 0.1wt% PER, the contact angle is reduced to 68.9°. This is because polyethylene glycol and pentaerythritol contain a large number of hydroxyl hydrophilic groups, so the hydrophilicity is improved.

[0086] The introduction of long-chain alkyl diamine brings hydrophilic amide polar groups. With the further increase of DDA content and when the addition amount of decanediamine is 6wt%, the contact angle decreases significantly and the hydrophilicity increases.

[0087] In summary, the preparation method of the soft and wrinkle-resistant polyester fiber of the present invention is to copolymerize dibasic acid, diol and long-chain alkyl diamine, and provide hydrogen bonding between molecular chains through the amide bond formed in the polymerization process, so as to enhance the interaction between molecular chains. The molecular chains are closely connected to each other under the action of a large number of hydrogen bonds, which is an effective method for improving the toughness and wrinkle resistance of the material; at the same time, the long-chain alkyl in the modified monomer contains more methylene flexible chain segments, and after being introduced into the main chain of the PET macromolecule, the macromolecule chain is more likely to move, so the relative rigidity of the modified PET fiber is lower than that of the PET fiber, which ensures the necessary softness of the fiber, and can prepare a polyester fiber product with both soft touch and good wrinkle resistance. The prepared fiber and fabric have both softness and wrinkle resistance, and can improve the hydrophilicity of the fiber and fabric, which is of great help to the post-treatment dyeing process.

[0088] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing soft and wrinkle-resistant polyester fiber, characterized in that: The following steps are involved: S1, adding a first monomer and a second monomer into a reaction kettle for esterification reaction; the reaction temperature is 240-260° C., the reaction time is 2-4 hours, and when the water output of the esterification reaction reaches 90% of the theoretical water output, the reaction requirement is met, and the esterification reaction is stopped; the first monomer is terephthalic acid, and the second monomer is ethylene glycol; S2, after the esterification is completed, a third monomer is added, and a polycondensation reaction is carried out after a pre-reaction of 0.5 to 1 hour under normal pressure, and the obtained copolymer is pelletized to obtain a modified polyester masterbatch; the third monomer is a long-chain alkyl diamine; the general structural formula of the third monomer is NH2CH2(CH2) m CH2NH2, wherein m is an integer from 4 to 10; S3, melt-spinning the polyester masterbatch obtained in step S2 to obtain soft and wrinkle-resistant polyester fibers.

2. The method for preparing the soft and wrinkle-resistant polyester fiber according to claim 1, characterized in that: In step S2, the amount of the third monomer added is 2-10% of the molar amount of the first monomer.

3. The method for preparing the soft and wrinkle-resistant polyester fiber according to claim 1, characterized in that: In step S1, the molar ratio of the first monomer to the second monomer is 1:(1-1.5).

4. The method for preparing the soft and wrinkle-resistant polyester fiber according to claim 1, characterized in that: In step S1, the catalyst added to the esterification reaction is Sb2O3, and the amount of the catalyst added is 400-600 ppm.

5. The method for preparing soft and wrinkle-resistant polyester fiber according to claim 1, characterized in that: In step S2, the specific process of the polycondensation reaction is: first, slowly evacuate to 80-100 Pa within 1-2 hours for pre-polycondensation treatment, then heat the system to 260-280°C and continue the reaction for 1-2 hours.

6. The method for preparing soft and wrinkle-resistant polyester fiber according to claim 1, characterized in that: The m is an integer of 6-10.

7. The method for preparing soft and wrinkle-resistant polyester fiber according to claim 2, characterized in that: The added amount of the third monomer is 4-6% of the molar amount of the first monomer.

8. A soft and wrinkle-resistant polyester fiber, characterized in that: The soft and wrinkle-resistant polyester fiber is prepared by the preparation method of any one of claims 1 to 7.

9. The soft and wrinkle-resistant polyester fiber according to claim 8, characterized in that The warp softness of the fabric woven from the soft and wrinkle-resistant polyester fiber reaches 1177.5 mN, and the warp wrinkle recovery angle reaches 98°.

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