A softening and anti-wrinkle polyester yarn and a method for preparing the same

Abstract

This application discloses a softer, wrinkle-resistant polyester filament and its preparation method, relating to the field of high-performance polyester. The softer, wrinkle-resistant polyester filament is obtained by melt spinning of a raw material containing a polyester melt. The polymerizable monomers of the polyester melt include purified terephthalic acid, linear alkyl diacid, and ethylene glycol in a molar ratio of 1:0.06–0.08:1.2–2.0, wherein the linear alkyl diacid has 8–12 carbon atoms. By introducing a branched alkyl diacid as a third monomer, this application effectively solves the problem in the prior art where polyester filament fabrics struggle to simultaneously achieve both softness and wrinkle resistance.

Description

Technical Field

[0001] This application relates to the field of high-performance polyester, and in particular to a softer, wrinkle-resistant polyester yarn and its preparation method. Background Technology

[0002] Polyester filament, or polyethylene terephthalate fiber, is an important synthetic fiber widely used in clothing, home textiles, and industrial textiles due to its high strength, good elasticity, wrinkle resistance, excellent dimensional stability, and lightfastness. However, the high crystallinity resulting from the highly ordered arrangement of conventional polyester molecular chains, while giving the fiber excellent mechanical properties, also leads to inherent problems such as relatively high rigidity and a stiff feel. When used to make fabrics requiring high comfort, such as underwear and bedding, the lack of softness in polyester filament is particularly pronounced, directly affecting the skin-friendly experience and wearing comfort of the final product.

[0003] To improve the softness of polyester filament, existing technologies involve copolymerization modification by introducing flexible monomers such as branched alkyl diols during the polyester polymerization stage. The effective embedding of these flexible segments can significantly reduce the regularity of the macromolecular chains, thereby reducing crystallinity and noticeably improving fiber softness. However, while disrupting the regular crystalline structure, these flexible segments also severely weaken the tight physical cross-linking points between molecular chains, which form the basis for elastic recovery. The consequence is a significant reduction in the fiber's elastic recovery rate, making the modified polyester filament more prone to irreversible plastic deformation during wear, resulting in a marked deterioration in wrinkle resistance and making it difficult for the fabric to maintain a smooth and crisp appearance after multiple wears or washes. Summary of the Invention

[0004] To address the problem that existing polyester filament fabrics struggle to balance softness and wrinkle resistance, this application provides a softer, wrinkle-resistant polyester filament and its preparation method. By introducing branched alkyl dicarboxylic acid as a third monomer, the resulting polyester exhibits a more balanced combination of softness and wrinkle resistance.

[0005] In a first aspect, this application provides a softer, wrinkle-resistant polyester filament, which is obtained by melt spinning from a raw material containing a polyester melt. The polymer monomers of the polyester melt include purified terephthalic acid, linear alkyl diacid, and ethylene glycol in a molar ratio of 1:0.06-0.08:1.2-2.0, wherein the linear alkyl diacid has 8-12 carbon atoms.

[0006] In any of the above technical solutions, the straight-chain alkyl diacid is selected from any one or more of octanoic acid, azelaic acid, sebacic acid, 1,11-undecanoic acid, and 1,12-dodecanoic acid.

[0007] The technical solution of this application uses a straight-chain alkyl diacid with a specific carbon chain length (C8-C12) as the third monomer, which is beneficial to achieving a balance between flexibility and wrinkle resistance compared to the branched alkyl diols commonly used in the prior art. Although the final improvement in softness may be slightly less than the latter, it causes significantly less damage to the regularity and crystallinity of the polyester chain segments, thus preventing a significant deterioration in the wrinkle resistance of the polyester filament fabric.

[0008] The reason for the above phenomenon may be that there is an essential difference in the polyester chain structure formed by the two third monomers. When alkyl diols are used, the long-chain alkyl segments are on both sides of flexible ether bonds, which are highly flexible, but they cause high damage to the rigid crystalline structure formed by terephthalic acid and ethylene glycol. In contrast, the linear alkyl diacid used in this application has rigid ester groups on both sides of the long-chain alkyl segments in the polyester chain, which improves flexibility less, but has a relatively weak effect on breaking the crystalline structure. This allows the polyester to maintain a relatively complete crystalline network as physical crosslinking points while obtaining moderate flexibility. This is the structural basis for maintaining its elastic recovery rate and preventing a serious decline in wrinkle resistance.

[0009] It should be noted that the carbon chain length of the straight-chain alkyl dicarboxylic acid used must be strictly controlled within this range. If the number of carbon atoms is too long, the excessively large flexible spacing will also lead to excessive weakening of the inter-chain forces, causing unacceptable deterioration in strength performance.

[0010] In any of the above technical solutions, the polymerizing monomer of the polyester melt includes a pyridine polycarboxylic acid monomer, and the molar ratio of terephthalic acid to the pyridine polycarboxylic acid monomer is 1:0.03 to 0.05.

[0011] In any of the above technical solutions, the pyridine-containing polycarboxylic acid monomer is selected from pyridine tricarboxylic acid and / or bipyridine tetracarboxylic acid.

[0012] For example, the pyridine tricarboxylic acid is 2,4,6-pyridine tricarboxylic acid; the bipyridine tetracarboxylic acid is 3,3',5,5'-bipyridine tetracarboxylic acid.

[0013] In any of the above technical solutions, the pyridine-containing polycarboxylic acid monomer forms a pyridine-containing polycarboxylic acid segment in the polyester, and the pyridine-containing polycarboxylic acid segment is coordinated by a transition metal ion.

[0014] The aforementioned transition metal ion coordination can be achieved as follows: a metal salt of a transition metal is added to the spinning oil, so that during the oiling and bundling process after extrusion and cooling, the metal ions adhere to the filament bundle along with the oil and penetrate into the spinning process, thereby coordinating and connecting with the pyridine polycarboxylic acid segments in the polyester.

[0015] In any of the above technical solutions, the proportion of transition metal salts in the oil is 1.5 to 3 wt%.

[0016] In any of the above technical solutions, the transition metal ion is selected from any one or more of copper ions, zinc ions, nickel ions or iron ions.

[0017] In any of the above technical solutions, the raw material for the polyester filament includes 1-2 wt% modified silica from polyester melt, wherein the modified silica is prepared by reacting silica sequentially with an aminosilane coupling agent and a long-chain anhydride.

[0018] In any of the above technical solutions, the mass ratio of silicon dioxide, aminosilane coupling agent and long-chain anhydride is 100:2-4:3-6.

[0019] In any of the above technical solutions, the long-chain anhydride is selected from lauric anhydride or stearic anhydride.

[0020] In any of the above technical solutions, the aminosilane coupling agent is selected from... aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, Any one or more of aminoethyl-γ-aminopropyltrimethoxysilane and N-β-aminoethyl-γ-aminopropyltriethoxysilane.

[0021] In any of the above technical solutions, the average particle size of the silicon dioxide is 20-100 nm, preferably 20-50 nm.

[0022] This application further introduces pyridine-containing polycarboxylic acids as a fourth monomer, and through the synergistic effect with transition metal ions and modified silica, constructs a physical reinforcement network, effectively compensating for the potential loss of elastic recovery rate due to the introduction of flexible segments. On the one hand, the nitrogen atom on the pyridine ring has a strong coordination ability. In the subsequent oiling process, the transition metal ions that penetrate the fiber can simultaneously coordinate with the pyridine groups on multiple polyester molecular chains, forming a dynamic coordination crosslinking network of "polyester-metal ion-polyester". This coordination bond has a certain strength and can undergo reversible breakage and recombination under stress, effectively dissipating energy and promoting deformation recovery, thus contributing to the improvement of wrinkle resistance. On the other hand, pyridine tricarboxylic acid or bipyridine tetracarboxylic acid itself forms branching points in the polyester chain. The highly active carboxyl groups at their ends that have not participated in the esterification reaction can form strong hydrogen bond interactions with the amide groups on the surface of specially modified silica, thereby forming a physical crosslinking network with silica as nodes.

[0023] It is worth noting that the modification treatment of silica uses long-chain acid anhydrides. Their primary function is to generate amide groups that can react with the terminal carboxyl groups of pyridine polycarboxylic acids by reacting amino groups (introduced by aminosilane coupling agents) on the silica surface. However, more importantly, long-chain alkyl groups are grafted onto the silica surface to improve compatibility with the polyester matrix and ensure that nano-silica is uniformly dispersed in the hydrophobic polyester melt. This avoids stress concentration and performance degradation caused by filler agglomeration, which is a prerequisite for achieving effective performance compensation.

[0024] Secondly, this application provides a method for preparing softer, wrinkle-resistant polyester yarn, comprising: According to the raw material ratio of polyester filament described in any of the first aspects, the polymer monomers are esterified and polycondensed to obtain polyester melt. An additive is added to the polyester melt through an online addition system. The uniformly mixed melt is then spun directly to obtain soft and wrinkle-resistant polyester filament.

[0025] In summary, this application has the following beneficial effects: This application resolves the contradiction between simultaneously achieving softness and wrinkle resistance in polyester filaments through the synergistic effect of multiple components. Its core lies in using linear alkyl diacids as the main flexibility regulating unit. While moderately improving the softness of polyester filaments and fabrics, it maximizes the preservation of polyester crystallinity, providing a fundamental guarantee for wrinkle resistance. Furthermore, by introducing pyridine-containing polycarboxylic acid monomers and leveraging the metal ion coordination during the spinning oiling process and the interfacial interaction with modified silica, a dual network of dynamic coordination crosslinking and physical hydrogen bonding crosslinking is constructed within the polyester matrix. Both, acting as reversible elastic nodes, can break and recombine under external forces, effectively dissipating energy, and after the external force is removed, promote the return of the molecular chains to their original position, thereby effectively compensating for and enhancing the fiber's elastic recovery capability. Detailed Implementation

[0026] Preparation Example Preparation Example 1 Modified silica was prepared by the following method: 1000g of silica with an average particle size of 30nm was added to 5L of toluene and ultrasonically dispersed for 30min. 30g of γ-aminopropyltrimethoxysilane was slowly added under mechanical stirring, and the mixture was heated to 110℃ and refluxed for 6 hours under nitrogen protection. After the reaction was complete, the temperature was lowered to 60℃, and 45g of lauric anhydride was added. The mixture was then refluxed at 100℃ for 8 hours under nitrogen protection. The reaction product was filtered, washed three times with anhydrous ethanol, and then vacuum dried at 80℃ for 12 hours to obtain modified silica.

[0027] Preparation Example 2 Modified silica was prepared by the following method: 1000g of silica with an average particle size of 20nm was added to 5L of toluene and ultrasonically dispersed for 30min; then, under mechanical stirring, it was slowly added to... Aminopropyltriethoxysilane was heated to 110°C and refluxed for 5 hours under nitrogen protection. After the reaction was completed, the temperature was lowered to 60°C, 30 g of lauric anhydride was added, and the mixture was refluxed at 100°C for 6 hours under nitrogen protection. The reaction product was filtered, washed three times with anhydrous ethanol, and then dried under vacuum at 80°C for 12 hours to obtain modified silica.

[0028] Preparation Example 3 Modified silica was prepared by the following method: 1000g of silica with an average particle size of 50nm was added to 5L of toluene and ultrasonically dispersed for 30min. 40g of N-β-aminoethyl-γ-aminopropyltrimethoxysilane was slowly added under mechanical stirring, and the mixture was heated to 110℃ and refluxed for 7h under nitrogen protection. After the reaction was complete, the temperature was lowered to 60℃, and 60g of stearic anhydride was added. The mixture was then refluxed at 100℃ for 10h under nitrogen protection. The reaction product was filtered, washed three times with anhydrous ethanol, and then vacuum dried at 80℃ for 12h to obtain modified silica.

[0029] Preparation Example 4 The modified silica differs from that in Preparation Example 1 in that lauric anhydride is replaced with an equal mass of acetic anhydride.

[0030] Preparation Example 5 The modified silica differs from that in Preparation Example 1 in that it is surface-modified only with a long-chain alkylsilane coupling agent. The specific steps are as follows: 1000g of silica with an average particle size of 30nm was added to 5L of toluene and ultrasonically dispersed for 30min. 50g of dodecyltrimethoxysilane was slowly added under mechanical stirring, and the mixture was heated to 110℃ and refluxed for 6 hours under nitrogen protection. After the reaction was completed and cooled to room temperature, the reaction product was filtered, washed three times with anhydrous ethanol, and then vacuum dried at 80℃ for 12 hours to obtain modified silica.

[0031] Example Example 1: A softer, wrinkle-resistant polyester yarn was prepared according to the following steps: Polyester synthesis: 10 mol purified terephthalic acid, 0.7 mol sebacic acid, 16 mol ethylene glycol, and 0.4 mol 2,4,6-pyridinetricarboxylic acid were added to a polymerization reactor. Under nitrogen protection, the temperature was gradually increased to 245℃ for esterification, with the esterification pressure controlled at 0.3 MPa and the reaction time at 3 hours until the conversion rate was greater than 90%. After esterification, the pressure was slowly released to atmospheric pressure, and antimony trioxide catalyst (0.03% of the total monomer mass) was added. Polycondensation was carried out at 260℃ under vacuum with an absolute pressure of 500 Pa for 45 minutes. Then, vacuum was continued, and polycondensation was carried out at 280℃ under an absolute pressure of <100 Pa for 3 hours to obtain a polyester melt with an intrinsic viscosity of 0.65 dL / g.

[0032] Oil preparation: First, add 2g of zinc acetate to 20g of water, heat to 40℃ and stir to dissolve. Then, slowly add the solution to a mixture of 73g of TK-3518 (commercially available emulsion spinning oil) and 5g of water, and stir at 1000rpm for 30 minutes to obtain an oil containing zinc acetate.

[0033] Spinning and Post-processing: The polyester melt obtained above is transported to the spinning box through a melt pipeline. Modified silica (1.5 wt% by weight of the polyester melt) is accurately added to the melt using an online addition system and a static mixer (Preparation Example 1). The uniformly mixed melt is precisely metered by a metering pump and extruded through a spinning assembly at 283°C to form a melt stream. The stream is cooled by a ring blower (air temperature 20°C, air humidity 60%, air velocity 0.5 m / s) to obtain nascent fibers. The nascent fibers are oiled and bundled using the zinc acetate-containing oiling agent described above. Then, the fibers are drawn by a guide disc and subjected to a first-stage hot drawing at 90°C, followed by a second-stage hot drawing at 120°C, for a total draw ratio of 3.5 times. Finally, the fibers are wound at a speed of 4350 m / min using a winding machine to obtain a soft, wrinkle-resistant polyester yarn with a specification of 65 dtex / 72F.

[0034] Example 2: A softer, wrinkle-resistant polyester yarn was prepared according to the following steps: Polyester synthesis: 10 mol purified terephthalic acid, 0.6 mol octanoic acid, 13 mol ethylene glycol, and 0.3 mol 2,4,6-pyridinetricarboxylic acid were added to a polymerization reactor. Under nitrogen protection, the temperature was gradually increased to 240℃ for esterification, with the esterification pressure controlled at 0.2 MPa and the reaction time at 2.5 hours until the conversion rate was greater than 90%. After esterification, the pressure was slowly released to atmospheric pressure, and antimony trioxide catalyst (0.03% of the total monomer mass) was added. Polycondensation was carried out at 260℃ under vacuum with an absolute pressure of 500 Pa for 35 minutes. Then, vacuum was continued, and polycondensation was carried out at 275℃ under an absolute pressure of <100 Pa for 2.5 hours to obtain a polyester melt with an intrinsic viscosity of 0.62 dL / g.

[0035] Oil preparation: First, add 1.5g of copper acetate to 20g of water, heat to 40℃ and stir to dissolve. Then, slowly add the solution to a mixture of 73.5g of TK-3518 (commercially available emulsion spinning oil) and 5g of water, and stir at 1000rpm for 30 minutes to obtain an oil containing copper acetate.

[0036] Spinning and Post-processing: The polyester melt obtained above is transported to the spinning box through a melt pipeline. Modified silica (1 wt% of the polyester melt mass, Preparation Example 2) is accurately added to the melt using an online addition system and a static mixer. The uniformly mixed melt is precisely metered by a metering pump and extruded through a spinning assembly at 285°C to form a melt stream. The stream is cooled by a ring blower (air temperature 20°C, air humidity 60%, air velocity 0.5 m / s) to obtain nascent fibers. The nascent fibers are oiled and bundled using the aforementioned copper acetate-containing oiling agent. They are then drawn by a guide disc and subjected to primary hot drawing at 95°C, followed by secondary hot drawing at 125°C, with a total draw ratio of 3.8 times. Finally, the fibers are wound at a speed of 4200 m / min using a winding machine to obtain a soft, wrinkle-resistant polyester yarn with a specification of 65 dtex / 72F.

[0037] Example 3: A softer, wrinkle-resistant polyester yarn was prepared according to the following steps: Polyester synthesis: 10 mol purified terephthalic acid, 0.8 mol 1,12-dodecanoic acid, 13 mol ethylene glycol, and 0.5 mol 3,3',5,5'-bipyridinetetracarboxylic acid were added to a polymerization reactor. Under nitrogen protection, the temperature was gradually increased to 250℃ for esterification. The esterification pressure was controlled at 0.24 MPa, and the reaction time was 3.5 hours until the conversion rate was greater than 90%. After esterification, the pressure was slowly released to atmospheric pressure, and antimony trioxide catalyst (0.03% of the total monomer mass) was added. Polycondensation was carried out at 265℃ under vacuum with an absolute pressure of 500 Pa for 50 min. Then, vacuum was continued, and polycondensation was carried out at 285℃ under an absolute pressure of <100 Pa for 3.5 hours to obtain a polyester melt with an intrinsic viscosity of 0.68 dL / g.

[0038] Oil preparation: First, add 3g of nickel acetate to 20g of water, heat to 50℃ and stir to dissolve. Then, slowly add the solution to a mixture of 72g of TK-3518 (commercially available emulsion spinning oil) and 5g of water, and stir at 1000rpm for 30 minutes to obtain an oil containing nickel acetate.

[0039] Spinning and Post-processing: The polyester melt obtained above is transported to the spinning box through a melt pipeline. Modified silica (2 wt% by weight of the polyester melt) is accurately added to the melt using an online addition system and a static mixer (Preparation Example 3). The uniformly mixed melt is precisely metered by a metering pump and extruded through a spinning assembly at 285°C to form a melt stream. The stream is cooled by a ring blower (air temperature 20°C, air humidity 60%, air velocity 0.5 m / s) to obtain nascent fibers. The nascent fibers are oiled and bundled using the aforementioned nickel acetate-containing oiling agent. They are then drawn by a guide disc and subjected to a first-stage hot drawing at 85°C, followed by a second-stage hot drawing at 120°C, with a total draw ratio of 3.6 times. Finally, the fibers are wound at a speed of 4500 m / min using a winding machine to obtain a soft, wrinkle-resistant polyester yarn with a specification of 65 dtex / 72F.

[0040] Example 4, a softer and wrinkle-resistant polyester yarn, differs from Example 1 in that, in the spinning and post-processing steps, an equal amount of modified silica from Example 4 is used instead of the modified silica from Example 1.

[0041] Example 5, a softer and wrinkle-resistant polyester yarn, differs from Example 1 in that, in the spinning and post-processing steps, an equal amount of modified silica from Example 5 is used instead of the modified silica from Example 1.

[0042] Example 6, a softer and wrinkle-resistant polyester yarn, differs from Example 1 in that zinc acetate is not added in the oil preparation process. The specific operation is as follows: take 75g of TK-3518 (commercially available spinning oil) and 25g of water into a mixture system, stir at 1000rpm for 30 minutes to obtain the oil.

[0043] Example 7, a softer and wrinkle-resistant polyester yarn, differs from Example 1 in that, in the polyester synthesis process, equimolar purified terephthalic acid is used instead of 2,4,6-pyridinetricarboxylic acid.

[0044] Comparative Example Comparative Example 1, a softer and wrinkle-resistant polyester yarn, differs from Example 1 in that, in the polyester synthesis process, equimolar adipic acid is used instead of sebacic acid.

[0045] Comparative Example 2, a softer and wrinkle-resistant polyester filament, differs from Example 1 in that, in the polyester synthesis process, equimolar amounts of 1,13-tridecanoic acid are used instead of sebacic acid.

[0046] Comparative Example 3, a softer and wrinkle-resistant polyester filament, differs from Example 1 in that, in the polyester synthesis process, equimolar purified terephthalic acid is used instead of sebacic acid.

[0047] Performance testing Experiment 1: Flexibility Test Using a plain weave structure, the polyester filaments prepared in the above embodiments and comparative examples were woven into fabrics with a warp density of 420 threads / 10 cm and a weft density of 320 threads / 10 cm. Three wrinkle-free and defect-free samples, each 20 cm × 2.5 cm in size, were cut from the fabric along both the warp and weft directions. The samples were conditioned for 24 hours under standard atmospheric conditions (temperature 20 ± 2℃, relative humidity 65% ​​± 5%). The bending stiffness (cN·cm) of the samples was measured using a fabric stiffness tester (LLY-01B electronic stiffness tester) according to GB / T 18318.1-2009 "Determination of bending properties of textiles - Part 1: Inclined plane method".

[0048] Experiment 2: Polyester filament breaking strength test: The test was conducted according to the requirements of GB / T 14344-2008 "Test Method for Tensile Properties of Chemical Fiber Filaments", with a clamp spacing of 500 mm and a tensile speed of 500 mm / min.

[0049] Experiment 3: Anti-wrinkle performance test Using a plain weave structure, the polyester filaments prepared in the above embodiments and comparative examples were woven into fabrics with a warp density of 420 threads / 10 cm and a weft density of 320 threads / 10 cm. Five wrinkle-free and defect-free samples, each 40 mm × 15 mm in size, were cut from the fabric along both the warp and weft directions. The samples were then conditioned for 24 hours under standard atmospheric conditions (temperature 20 ± 2 °C, relative humidity 65% ​​± 5%).

[0050] Use a crease recovery angle tester. Fold the sample lengthwise, with the right sides of the fabric facing each other, and place it under the transparent pressure plate of the instrument. Apply a specified load (10N) of weight and maintain pressure for 5 minutes. Quickly remove the load, clamp the folded sample with the sample holder, and immediately transfer it to the sample stage of the tester, allowing one wing to unfold freely. Allow the sample to recover precisely for 5 minutes (measuring the elastic recovery angle), and then read its recovery angle using a protractor or the instrument's automatic measurement system. Record the recovery angles in the warp and weft directions separately, and use the sum of the warp and weft recovery angles (total recovery angle, unit: °) as the evaluation index. The larger this value, the better the wrinkle resistance of the fabric.

[0051] Table 1 Performance Test Results Analysis of experimental results: Example 4 (using acetic anhydride instead of lauric anhydride in modified silica) showed worse performance in both tensile strength and total recovery angle compared to Example 1, indicating that the lack of long-chain alkyl groups in the modified silica negatively impacts both strength and wrinkle resistance. This may be because, although the amide groups introduced by acetic anhydride can react with the terminal carboxyl groups of pyridine polycarboxylic acids, the lack of long-chain alkyl groups reduces the compatibility between silica and the polyester melt, leading to uneven filler dispersion and an inability to form an effective physical crosslinking network, thereby weakening elastic recovery and strength.

[0052] Example 5 (modified silica modified only with long-chain alkylsilane coupling agents) showed a worse overall recovery angle compared to Example 1, indicating that the lack of amide groups in the modified silica negatively impacts its anti-wrinkle properties. This may be because, while the long-chain alkylsilane coupling agent improves the compatibility of silica, the lack of amide groups on its surface prevents it from forming hydrogen bonds with the terminal carboxyl groups of pyridine polycarboxylic acids, resulting in an incomplete physical cross-linking network and reduced elastic recovery.

[0053] Example 6 (without metal salt added to the oil) showed a worse overall recovery angle compared to Example 1, indicating that the lack of metal ion coordination has a negative impact on wrinkle resistance. This may be because the absence of metal ions prevents the formation of a dynamic coordination crosslinking network of "polyester-metal ion-polyester," reducing reversible crosslinking points and thus decreasing the fiber's deformation recovery ability under stress.

[0054] Example 7 (polyester synthesis without the addition of pyridine polycarboxylic acid monomers) showed a worse overall recovery angle compared to Example 1, indicating that the absence of pyridine polycarboxylic acid monomers negatively impacts strength and wrinkle resistance. This may be because the lack of pyridine polycarboxylic acid results in the polyester chain lacking both coordination crosslinking points and the ability to form hydrogen bonds with modified silica. The absence of a double crosslinking network weakens the intermolecular forces and reduces the elastic recovery rate.

[0055] Comparative Example 1 (using adipic acid instead of sebacic acid) showed poorer performance in bending stiffness and fabric softness compared to Example 1, indicating that a short carbon chain (C6) has a negative impact on softness. This may be because the shorter carbon chain of adipic acid results in insufficient flexibility adjustment and less damage to polyester crystallinity, leading to higher fiber rigidity and a stiffer hand feel.

[0056] Comparative Example 2 (using 1,13-tetadecanedioic acid instead of sebacic acid) showed worse performance in terms of breaking strength and total recovery angle compared to Example 1, indicating that excessively long carbon chains (C13) have a negative impact on strength and wrinkle resistance. This may be because excessively long carbon chains severely disrupt the regularity of polyester molecular chains, significantly reducing crystallinity and weakening the intermolecular forces, leading to decreased strength and deteriorated elastic recovery.

[0057] Comparative Example 3 (without linear alkyl diacids) showed poorer flexural stiffness compared to Example 1, indicating the significant impact of linear alkyl diacids on improving softness. This may be because the absence of flexible segments meant the polyester molecular chains maintained high crystallinity and rigidity, resulting in a stiff fiber feel and insufficient softness.

[0058] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A softer, wrinkle-resistant polyester filament, characterized in that, It is obtained by melt spinning of raw materials containing polyester melt, wherein the polymer monomers of the polyester melt include purified terephthalic acid, linear alkyl diacid and ethylene glycol in a molar ratio of 1:0.06-0.08:1.2-2.0, and the linear alkyl diacid has 8-12 carbon atoms.

2. The softened and wrinkle-resistant polyester yarn according to claim 1, characterized in that, The straight-chain alkyl diacid is selected from any one or more of octanoic acid, azelaic acid, sebacic acid, 1,11-undecanoic acid, and 1,12-dodecanoic acid.

3. The softened and wrinkle-resistant polyester yarn according to claim 1, characterized in that, The monomers of the polyester melt include pyridine polycarboxylic acid monomers, and the molar ratio of terephthalic acid to pyridine polycarboxylic acid monomers is 1:0.03 to 0.

05.

4. The softened and wrinkle-resistant polyester yarn according to claim 3, characterized in that, The pyridine-containing polycarboxylic acid monomer is selected from pyridine tricarboxylic acid and / or bipyridine tetracarboxylic acid.

5. The softened and wrinkle-resistant polyester yarn according to claim 3, characterized in that, The pyridine-containing polycarboxylic acid monomer forms pyridine-containing polycarboxylic acid segments in the polyester, and the pyridine-containing polycarboxylic acid segments are coordinated with transition metal ions.

6. The softened and wrinkle-resistant polyester yarn according to claim 5, characterized in that, The transition metal ions are selected from any one or more of copper ions, zinc ions, nickel ions, or iron ions.

7. The softened and wrinkle-resistant polyester yarn according to claim 1, characterized in that, The raw material for the polyester filament includes 1-2 wt% modified silica from polyester melt, which is prepared by reacting silica sequentially with an aminosilane coupling agent and a long-chain anhydride.

8. The softened and wrinkle-resistant polyester yarn according to claim 7, characterized in that, The mass ratio of the silica, aminosilane coupling agent, and long-chain anhydride is 100:2-4:3-6.

9. The softened and wrinkle-resistant polyester yarn according to claim 8, characterized in that, The long-chain anhydride is selected from lauric anhydride or stearic anhydride.

10. A method for preparing a softer, wrinkle-resistant polyester filament, characterized in that, include: According to the raw material ratio of polyester filament as described in any one of claims 1 to 9, the polymer monomer is esterified and polycondensed to obtain polyester melt. An additive is added to the polyester melt through an online addition system. The uniformly mixed melt is then spun directly to obtain soft and wrinkle-resistant polyester filament.

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