Elastic cotton-like ramie polyester fiber and preparation method thereof

Abstract

The application relates to the polyester preparation technical field, and particularly discloses a stretchable cotton-imitating hemp polyester fiber and a preparation method thereof. The stretchable cotton-imitating hemp polyester fiber comprises core yarn and a winding layer spirally wound outside the core yarn, the core yarn is a skin-core composite structure, and the skin layer is composed of the following components in parts by weight: 45-55 parts of thermoplastic polyester elastomer, 25-35 parts of polytrimethylene terephthalate, and 5-8 parts of epoxy-based dynamic vulcanization elastomer; and the core layer is composed of the following components in parts by weight: 8-12 parts of copolymerized polyphenylene sulfide. The application adopts the skin-core composite structure, the thermoplastic polyester elastomer and the polytrimethylene terephthalate in the skin layer form a continuous elastic matrix under the compatibilization of the epoxy-based dynamic vulcanization elastomer, the polytetrafluoroethylene micro powder in the core layer forms a nanofiber network, and the copolymerized polyphenylene sulfide dispersed phase is in the form of axially oriented fibers, so that the elastic recovery retention rate of the fiber after multiple stretching cycles is improved.

Description

Technical Field

[0001] This application relates to the field of polyester preparation technology, and more specifically, it relates to an elastic cotton-linen-like polyester fiber and its preparation method. Background Technology

[0002] Polyester fiber boasts advantages such as high strength, good elasticity, excellent abrasion resistance, and good heat and chemical resistance, making it widely used in clothing, home textiles, and industrial textiles. As consumers' demands for comfort and functionality in textiles continue to rise, the development of differentiated polyester fibers has become a hot research topic in the industry. Among them, cotton-linen-like polyester fiber has attracted widespread market attention due to its combination of the crispness of polyester and the breathability, moisture absorption, and natural texture of cotton and linen fabrics.

[0003] Existing elastic cotton-linen-like polyester fibers mostly use spandex filaments and polypropylene terephthalate fibers twisted together as the core yarn. However, there are differences in the elastic modulus and fatigue life between spandex filaments and polypropylene terephthalate fibers. During repeated stretching, stress concentration and micro-damage accumulation are easily generated at the twisting nodes, which can lead to a gradual decline in the elastic recovery performance of the core yarn. After multiple stretching cycles, the elasticity decreases significantly. Summary of the Invention

[0004] To address the problem that existing elastic cotton-linen-like polyester fibers tend to have a gradual decline in the elastic recovery performance of the core yarn, and a significant decrease in elasticity after multiple stretching cycles, this application provides an elastic cotton-linen-like polyester fiber and its preparation method.

[0005] This application provides an elastic cotton-linen-like polyester fiber and its preparation method, which adopts the following technical solution: In the first aspect, this application provides an elastic cotton-linen-like polyester fiber, which adopts the following technical solution: An elastic cotton-linen-like polyester fiber includes a core yarn and a spiral wound layer wound around the outside of the core yarn. The core yarn has a core-sheath composite structure, and the sheath layer is composed of the following components in parts by weight: 45-55 parts of thermoplastic polyester elastomer, 25-35 parts of polypropylene terephthalate, 5-8 parts of epoxy-based dynamic vulcanized elastomer, and 0.2-0.5 parts of antioxidant. The core layer is composed of the following components in parts by weight: 8-12 parts of copolymerized polyphenylene sulfide, 3-6 parts of polytetrafluoroethylene micro powder, and 0.5-1.0 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer. The surface of the core yarn is coated with a maleic anhydride-grafted polyolefin coating. The spiral wound layer is formed by spirally winding super-cotton-like polyester fiber and linen-like slub yarn around the outside of the core yarn in opposite directions. Both the super-cotton-like polyester fiber and the linen-like slub yarn contain polyethylene terephthalate and glycidyl methacrylate-grafted polyester.

[0006] By adopting the above technical solution, due to the use of a core-sheath composite structure, the thermoplastic polyester elastomer and polypropylene terephthalate in the sheath layer form a continuous elastic matrix under the compatibilizing effect of the epoxy-based dynamically vulcanized elastomer. In the core layer, polytetrafluoroethylene micropowder forms a nanofiber network, and the copolymerized polyphenylene sulfide dispersed phase exhibits an axially oriented fiber morphology. The two constitute a composite skeleton of rigid support and elastic buffer, which allows the stress to be evenly distributed during repeated stretching and inhibits the propagation of micro-damage. At the same time, the maleic anhydride-grafted polyolefin coating on the surface of the core yarn and the reactive groups contained in the glycidyl methacrylate-grafted polyester in the winding layer can form a chemical bonding interface, enhancing the bonding strength between the core yarn and the winding layer and reducing the additional stress disturbance to the core yarn caused by the slippage of the winding layer. Therefore, the elastic recovery retention rate of the fiber after multiple stretching cycles is improved, solving the problem that existing elastic cotton-linen-like polyester fibers are prone to gradual decay of the elastic recovery performance of the core yarn and significant decrease in elasticity after multiple stretching cycles.

[0007] Preferably, the copolymerized polyphenylene sulfide is a copolymer of p-dichlorobenzene, isophthalic acid and sodium sulfide, and the molar ratio is 1:0.15~0.25:1.05~1.10, and the melting point of the copolymerized polyphenylene sulfide is 235~245℃; the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0008] By adopting the above technical solution, using copolymerized polyphenylene sulfide and polytetrafluoroethylene micro powder, the core layer forms a composite skeleton with rigid support and elastic buffering, which more effectively inhibits the spread of micro-damage; at the same time, hindered phenolic antioxidants are selected to reduce degradation during thermal processing and maintain matrix properties, thereby further improving the elastic recovery retention rate of the fiber after multiple stretching cycles.

[0009] Preferably, the mass ratio of the sheath to the core layer of the core yarn is 3~4:1, the polytetrafluoroethylene micro powder of the core layer forms a nanofiber network in situ, the copolymer polyphenylene sulfide dispersed phase of the core layer is in the form of nanofibers oriented along the fiber axis, and the mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is 5%~8%.

[0010] By adopting the above technical solution, through the core-sheath mass ratio and the composite morphology of polytetrafluoroethylene nanofiber network and copolymer polyphenylene sulfide axially oriented fibers in the core layer, the repeated tensile stress is more evenly distributed inside the core yarn and stress concentration is reduced; at the same time, by controlling the mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer, the interfacial compatibility between the components of the core layer is ensured, thereby synergistically improving the elasticity and durability of the fiber.

[0011] Preferably, the thickness of the maleic anhydride-grafted polyolefin coating is 0.5~1.5μm, and the mass fraction of glycidyl methacrylate-grafted polyester in the super cotton-like polyester fiber and the hemp-like slub yarn is 2%~3%.

[0012] By adopting the above technical solution, through the maleic anhydride-grafted polyolefin coating and the methacrylate-grafted polyester in the super cotton-like polyester fiber and the hemp-like slub yarn, sufficient and stable reactive groups are formed between the core yarn surface and the winding layer, achieving uniform chemical bonding under hot pressing conditions, thereby enhancing the interfacial bonding strength between the core yarn and the winding layer and improving the anti-slip performance.

[0013] Secondly, this application provides a method for preparing elastic cotton-linen-like polyester fiber, using the following technical solution: A method for preparing elastic cotton-linen-like polyester fiber, applied to the above-mentioned elastic cotton-linen-like polyester fiber, includes the following steps: S1: By weight, thermoplastic polyester elastomer, polypropylene terephthalate, epoxy dynamic vulcanized elastomer and antioxidant are melt-blended, granulated and dried to obtain skin-blended granules; S2: By weight, the copolymer polyphenylene sulfide, polytetrafluoroethylene micro powder and ethylene-methyl acrylate-glycidyl methacrylate terpolymer are melt-blended, granulated and dried to obtain core layer blended granules; S3: Using a core-sheath composite melt spinning equipment, the sheath blended granules and the core blended granules are melted separately and then extruded through a core-sheath composite spinneret to form core-sheath structured nascent fibers. After cooling, oiling, two-stage hot stretching and low-temperature annealing, the core yarn is obtained. S4: Apply a maleic anhydride-grafted polyolefin coating to the surface of the core yarn online, and obtain the coated core yarn after drying; S5: Using coated core yarn as core yarn, super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound around the outside of core yarn in opposite directions to obtain wound composite fiber; S6: The wound composite fiber is hot-pressed and cross-linked under heating and pressure to obtain elastic cotton-linen-like polyester fiber.

[0014] By adopting the above technical solution, the following processes are carried out in sequence: sheath and core layer blending and granulation, sheath and core composite melt spinning, surface coating application, spiral winding and hot-press cross-linking and shaping. A composite skeleton with rigid support and elastic buffer is constructed inside the core yarn, and a chemical bonding interface is formed between the core yarn and the winding layer, thereby stably preparing elastic cotton-linen-like polyester fiber with high elasticity, durability and anti-slip properties.

[0015] Preferably, in step S1, the melt blending is performed using a twin-screw extruder with an extrusion temperature of 190~225℃, and the drying temperature after granulation is 100~110℃. In step S2, the melt blending is performed using a twin-screw extruder with an extrusion temperature of 230~265℃. The drying temperature after granulation is 120~130℃, the drying vacuum degree is ≤-0.08MPa, and the moisture content after drying is ≤50ppm.

[0016] By adopting the above technical solutions, the extrusion temperature and drying conditions of the sheath and core blend are controlled respectively, so that each component can be fully melted and mixed at its own suitable temperature and thermal degradation is avoided. At the same time, the moisture content is controlled to reduce bubbles and broken yarn defects during the spinning process, thereby ensuring the continuous and stable forming of the core yarn and the uniformity of the internal structure.

[0017] Preferably, in step S3, the extrusion temperature of the outer layer is 200~230℃, the extrusion temperature of the core layer is 240~270℃, the spinneret temperature is 230~235℃, the spinning speed is 900~1200m / min, the cooling air temperature is 20~25℃, the air velocity is 0.4~0.6m / s, the relative humidity is 65%~75%, the oil concentration of the oiling agent is 2.5%~3.5%, the two-stage hot drawing is 2.8~3.2 times at 90~100℃ for the first stage and 1.4~1.6 times at 110~120℃ for the second stage, and the low-temperature annealing temperature is 120~125℃ for 30~60 seconds.

[0018] By adopting the above technical solution, the stable molding of the skin-core structure is achieved through the extrusion temperature difference between the skin and the core layer and the spinneret temperature. Combined with appropriate two-stage hot stretching ratio and low-temperature annealing, the polytetrafluoroethylene micro powder in the core layer forms a nanofiber network in situ and induces the copolymerized polyphenylene sulfide dispersed phase to be oriented along the fiber axis, thereby obtaining the desired composite skeleton morphology to improve elasticity and durability.

[0019] Preferably, in step S4, the application of the maleic anhydride-grafted polyolefin coating is performed by immersing the core yarn in a maleic anhydride-grafted polyolefin aqueous emulsion with a mass fraction of 2.0% to 2.5% for 2 to 5 seconds, and then drying it at 80 to 90°C.

[0020] By adopting the above technical solution, using an online dip-coating method and controlling the emulsion concentration, immersion time, and drying temperature, a maleic anhydride-grafted polyolefin coating with uniform thickness and good adhesion is formed on the core yarn surface, providing a stable reactive interface basis for the subsequent chemical crosslinking between the core yarn and the winding layer.

[0021] Preferably, in step S5, the spiral winding direction of the super cotton-like polyester fiber is S-direction, and the winding direction of the hemp-like slub yarn is Z-direction, with a winding density of 900~1100T / m and a winding tension of 10~15cN.

[0022] By adopting the above technical solution, spiral winding is performed in opposite directions with different winding density and tension, so that the super cotton-like polyester fiber and the linen-like slub yarn form a tight and uniform mechanical contact with the coating on the core yarn surface, providing a sufficient and effective reaction interface area for subsequent hot-press crosslinking.

[0023] Preferably, in step S6, the temperature for hot-press cross-linking and shaping is 120~130℃, the pressure is 0.4~0.6MPa, and the processing time is 2~3 minutes.

[0024] By adopting the above technical solution, hot-press cross-linking and shaping under temperature, pressure and time allows maleic anhydride-grafted polyolefin and glycidyl methacrylate-grafted polyester to undergo sufficient chemical cross-linking reaction to form a stable covalent bond interface, while avoiding damage to the fiber matrix caused by excessively high temperature, thereby obtaining excellent anti-slip properties and structural stability.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts a core-sheath composite structure, the thermoplastic polyester elastomer and polypropylene terephthalate in the sheath layer form a continuous elastic matrix under the compatibilizing effect of the epoxy-based dynamic vulcanized elastomer. In the core layer, polytetrafluoroethylene micropowder forms a nanofiber network, and the copolymerized polyphenylene sulfide dispersed phase has an axially oriented fiber morphology. The two constitute a composite skeleton of rigid support and elastic buffer, so that the stress during repeated stretching can be evenly distributed and the propagation of micro-damage can be inhibited. At the same time, the maleic anhydride-grafted polyolefin coating on the surface of the core yarn and the reactive groups contained in the glycidyl methacrylate-grafted polyester in the winding layer can form a chemical bonding interface, which enhances the bonding strength between the core yarn and the winding layer and reduces the additional stress disturbance of the core yarn caused by the slippage of the winding layer. Therefore, it improves the elastic recovery retention rate of the fiber after multiple stretching cycles, and solves the problem that the elastic recovery performance of the core yarn of existing elastic cotton-linen polyester fibers is prone to gradual decay and significant decrease in elasticity after multiple stretching cycles.

[0026] 2. This application involves setting a maleic anhydride-grafted polyolefin coating on the surface of the core yarn and introducing glycidyl methacrylate-grafted polyester into the super cotton-like polyester fiber and the linen-like slub yarn of the winding layer. The reactive groups contained in both fibers undergo a chemical cross-linking reaction under hot and pressing conditions to form a covalent bond interface, which enhances the bonding strength between the core yarn and the winding layer and reduces the axial slippage of the winding layer during long-term use and washing, thereby improving the structural stability of the fiber and the durability of the cotton-like linen appearance.

[0027] 3. This application achieves good interfacial compatibility among the components in the core layer by adjusting the mass ratio of the core yarn to the core layer, the morphology and structure of the polytetrafluoroethylene micro powder and the copolymer polyphenylene sulfide, and the mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer. At the same time, the composite morphology of the rigid skeleton and the elastic matrix further optimizes the stress transmission path, reduces stress concentration and micro-damage accumulation, thereby synergistically improving the fatigue life and elastic durability of the fiber under dynamic tensile conditions. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for preparing elastic cotton-linen-like polyester fiber provided in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical concept: Existing elastic cotton-linen-like polyester fibers mostly use spandex filaments and polypropylene terephthalate fibers twisted together as core yarn. However, the elastic modulus and fatigue life of the two elastic materials are different. During repeated stretching, stress concentration and micro-damage accumulation occur at the twisting nodes, resulting in a gradual decline in the elastic recovery performance of the core yarn.

[0031] Based on this, this application utilizes a continuous elastic matrix formed by thermoplastic polyester elastomer and polypropylene terephthalate in the skin layer under the compatibilizing effect of epoxy-based dynamically vulcanized elastomer. In the core layer, polytetrafluoroethylene micropowder forms a nanofiber network in situ during melt spinning and stretching. Simultaneously, the copolymerized polyphenylene sulfide dispersed phase is oriented along the fiber axis to form a rigid fiber morphology. The two constitute a composite skeleton of rigid support and elastic buffer, which makes the tensile stress uniformly distributed and inhibits the propagation of micro-damage. Furthermore, a maleic anhydride-grafted polyolefin coating is applied to the surface of the core yarn. Glyceryl methacrylate-grafted polyester is introduced into the super cotton-like polyester fiber and hemp-like slub yarn of the winding layer. The reactive groups contained in the two undergo a chemical cross-linking reaction during the hot-press cross-linking and shaping process to form a covalent bond interface, which enhances the bonding strength between the core yarn and the winding layer and reduces the additional stress disturbance of the core yarn caused by the slippage of the winding layer. This improves the elastic recovery retention rate of the fiber after multiple stretching cycles, thereby solving the problem of elastic decay in the prior art.

[0032] Unless otherwise specified, all experimental methods used below are conventional methods. All materials, reagents, methods, and instruments used, unless otherwise specified, are conventional materials, reagents, methods, and instruments in this field, which can be obtained commercially or prepared according to literature methods by those skilled in the art.

[0033] Thermoplastic polyester elastomer: Hytrel manufactured by DuPont, USA G3548L thermoplastic polyester elastomer is suitable for extrusion molding; this product is a block copolymer containing polyester hard segments and polyether soft segments, and has excellent flexibility and fatigue resistance.

[0034] Polypropylene terephthalate: Sorona manufactured by DuPont, USA Poly(propylene terephthalate) fiber grade resin; this product is formed by the condensation polymerization of terephthalic acid and 1,3-propanediol, and has good elasticity and processing properties.

[0035] Epoxy-based dynamically vulcanized elastomer: Lotader manufactured by Arkema, France AX8900 is a random terpolymer of ethylene-methyl acrylate-glycidyl methacrylate. It is prepared by high-pressure polymerization and can be used as a reactive compatibilizer in polyester alloy systems.

[0036] Antioxidant: Irganox manufactured by BASF Antioxidant 1010, chemically named pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], CAS number 6683-19-8, molecular formula C73H108O12; this product is a multi-functional hindered phenolic antioxidant that provides protection against thermal oxidative degradation and has good compatibility with polyester matrix.

[0037] Polytetrafluoroethylene (PTFE) micro powder: The PTFE micro powder produced by Sanye Technology (Tianjin) Co., Ltd. is a low molecular weight micron-sized white PTFE powder prepared by a special method. It has the characteristics of high crystallinity, good dispersibility and large specific surface area.

[0038] Ethylene-methyl acrylate-glycidyl methacrylate terpolymer: using Lotader manufactured by Arkema, France. AX8900 is used as a compatibilizer in core layer blending systems.

[0039] Maleic anhydride-grafted polyolefin: Maleic anhydride-grafted polyethylene produced by Nanjing Sutai Polymer Technology Co., Ltd. This product uses maleic anhydride as a functional monomer to modify polyethylene matrix resin. It contains maleic anhydride functional groups and is suitable as a resin alloy compatibilizer and adhesion promoter.

[0040] Polyethylene terephthalate: Fiber-grade polyethylene terephthalate chips produced by Sinopec Yizheng Chemical Fiber Co., Ltd.

[0041] Preparation Example 1: Preparation of Copolymerized Polyphenylene Sulfide In a high-pressure reactor equipped with a stirrer, thermometer, and pressure gauge, p-dichlorobenzene, isophthalic acid, and sodium sulfide nonahydrate were added in a molar ratio of 1:0.2:1.075, with N-methylpyrrolidone as the solvent. The amount of solvent was four times the total mass of the solids. Under nitrogen protection, the reactor temperature was raised to 265°C, the reaction pressure was controlled at 2.25 MPa, and the reaction was carried out for 7 hours. After the reaction was completed, the mixture was cooled to room temperature, and the pressure was slowly released to atmospheric pressure. The reaction mixture was then slowly poured into 10 times its volume of deionized water, stirred to precipitate, and filtered to obtain the crude product. The crude product was washed twice with N-methylpyrrolidone, three times with deionized water, and twice with anhydrous ethanol. After each washing, the product was filtered and separated. The washed product was placed in a vacuum drying oven and dried at 130°C and a vacuum degree ≤ -0.08 MPa for 12 hours to obtain the copolymerized polyphenylene sulfide.

[0042] Preparation Example 2: Preparation of Glycidyl Methacrylate Grafted Polyester Polyethylene terephthalate (PET) chips were dried in a vacuum drying oven at 120°C for 6 hours, with the moisture content controlled below 50 ppm. 100 parts by weight of the dried PET, 4 parts by weight of glycidyl methacrylate, and 0.4 parts by weight of benzoyl peroxide were weighed and mixed in a high-speed mixer at room temperature for 7.5 minutes at a speed of 400 rpm to obtain a premix. The premixed material was fed into a twin-screw extruder for melt grafting reaction. The temperatures of each section of the extruder were set as follows: Zone 1 245℃, Zone 2 255℃, Zone 3 265℃, Zone 4 270℃, and the die head temperature was 270℃. The screw speed was 150 rpm, the feed speed was 12.5 rpm, and the extruded strip was cooled in a water bath and granulated to obtain glycidyl methacrylate grafted polyester granules. The granules were placed in a Soxhlet extractor and refluxed with acetone as solvent for 12 hours to remove unreacted glycidyl methacrylate and homopolymer. The extracted product was then dried in a vacuum drying oven at 80°C for 8 hours to complete the preparation.

[0043] To better understand the above technical solutions, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments.

[0044] The following is a further description with reference to the embodiments: Example 1: Please refer to the appendix Figure 1A type of elastic cotton-linen-like polyester fiber includes a core yarn and a spiral wound layer wound around the outside of the core yarn. The core yarn has a core-sheath composite structure, and the sheath layer is composed of the following components in parts by weight: 50 parts of thermoplastic polyester elastomer, 30 parts of polypropylene terephthalate, 6.5 parts of epoxy dynamic vulcanized elastomer, and 0.35 parts of antioxidant. The core layer is composed of the following components in parts by weight: 10 parts of copolymerized polyphenylene sulfide, 4.5 parts of polytetrafluoroethylene micro powder, and 0.75 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer. The surface of the core yarn is provided with a maleic anhydride-grafted polyolefin coating. The spiral wound layer is formed by spirally wound ultra-cotton-like polyester fiber and linen-like slub yarn in opposite directions around the outside of the core yarn. Both ultra-cotton-like polyester fiber and linen-like slub yarn contain polyethylene terephthalate and glycidyl methacrylate-grafted polyester.

[0045] The copolyphenylene sulfide is a copolymer of dichlorobenzene, isophthalic acid and sodium sulfide, with a molar ratio of 1:0.2:1.075. The melting point of the copolyphenylene sulfide is 240℃. The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0046] The mass ratio of the sheath to the core layer of the core yarn is 3.5:1. The polytetrafluoroethylene micro powder in the core layer forms a nanofiber network in situ. The copolymer polyphenylene sulfide dispersed phase in the core layer is in the form of nanofibers oriented along the fiber axis. The mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is 6.5%.

[0047] The thickness of the maleic anhydride-grafted polyolefin coating is 1 μm, and the mass fraction of glycidyl methacrylate-grafted polyester in both the super cotton-like polyester fiber and the linen-like slub yarn is 2.5%.

[0048] A method for preparing elastic cotton-linen-like polyester fiber, applied to the above-mentioned elastic cotton-linen-like polyester fiber, includes the following steps: S1: By weight, thermoplastic polyester elastomer, polypropylene terephthalate, epoxy dynamic vulcanized elastomer and antioxidant are melt-blended, granulated and dried to obtain skin-blended granules; The melt blending process was carried out using a twin-screw extruder with an extrusion temperature of 207.5℃, and the drying temperature after granulation was 105℃.

[0049] S2: By weight, the copolymer polyphenylene sulfide, polytetrafluoroethylene micro powder and ethylene-methyl acrylate-glycidyl methacrylate terpolymer are melt-blended, granulated and dried to obtain core layer blended granules; The melt blending process was carried out using a twin-screw extruder with an extrusion temperature of 247.5℃. The drying temperature after granulation was 125℃, the drying vacuum degree was ≤-0.08MPa, and the moisture content after drying was ≤50ppm.

[0050] S3: Using a core-sheath composite melt spinning equipment, the sheath blended granules and the core blended granules are melted separately and then extruded through a core-sheath composite spinneret to form core-sheath structured nascent fibers. After cooling, oiling, two-stage hot stretching and low-temperature annealing, the core yarn is obtained. The extrusion process included a sheath extrusion temperature of 215℃, a core extrusion temperature of 255℃, a spinneret temperature of 232.5℃, a spinning speed of 1050m / min, a cooling air temperature of 22.5℃, an air velocity of 0.5m / s, a relative humidity of 70%, an oil concentration of 2.75%, two-stage hot drawing with the first stage at 95℃ for a 3-fold draw and the second stage at 115℃ for a 1.5-fold draw, a low-temperature annealing temperature of 122.5℃, and an annealing time of 45 seconds.

[0051] S4: Apply a maleic anhydride-grafted polyolefin coating to the surface of the core yarn online, and obtain the coated core yarn after drying; The process of applying the maleic anhydride-grafted polyolefin coating involves immersing the core yarn in a 2.25% (by mass) maleic anhydride-grafted polyolefin aqueous emulsion for 3.5 seconds, followed by drying at 85°C.

[0052] S5: Using coated core yarn as core yarn, super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound around the outside of core yarn in opposite directions to obtain wound composite fiber; During spiral winding, the super-imitation cotton polyester fiber is wound in the S direction, and the imitation linen slub yarn is wound in the Z direction. The winding density is 1000T / m and the winding tension is 12.5cN.

[0053] S6: The wound composite fiber is hot-pressed and cross-linked under heating and pressure to obtain elastic cotton-linen-like polyester fiber.

[0054] The hot-press cross-linking and setting temperature is 125℃, the pressure is 0.5MPa, and the processing time is 2.5 minutes.

[0055] Example 2: This example differs from Example 1 above in that: An elastic cotton-linen-like polyester fiber includes a core yarn and a spiral wound layer wound around the outside of the core yarn. The core yarn has a core-sheath composite structure, and the sheath layer is composed of the following components in parts by weight: 55 parts of thermoplastic polyester elastomer, 35 parts of polypropylene terephthalate, 8 parts of epoxy-modified dynamic vulcanized elastomer, and 0.5 parts of antioxidant. The core layer is composed of the following components in parts by weight: 12 parts of copolymerized polyphenylene sulfide, 6 parts of polytetrafluoroethylene micro powder, and 1.0 part of ethylene-methyl acrylate-glycidyl methacrylate terpolymer. The surface of the core yarn is coated with maleic anhydride-grafted polyolefin. The spiral wound layer is formed by spirally wound ultra-cotton-like polyester fiber and linen-like slub yarn in opposite directions around the outside of the core yarn. Both the ultra-cotton-like polyester fiber and the linen-like slub yarn contain polyethylene terephthalate and glycidyl methacrylate-grafted polyester.

[0056] The copolyphenylene sulfide is a copolymer of dichlorobenzene, isophthalic acid and sodium sulfide, with a molar ratio of 1:0.25:1.1. The melting point of the copolyphenylene sulfide is 245℃. The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0057] The mass ratio of the sheath to the core layer of the core yarn is 4:1. The polytetrafluoroethylene micro powder in the core layer forms a nanofiber network in situ. The copolymer polyphenylene sulfide dispersed phase in the core layer is in the form of nanofibers oriented along the fiber axis. The mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is 8%.

[0058] The thickness of the maleic anhydride-grafted polyolefin coating is 1.5 μm, and the mass fraction of glycidyl methacrylate-grafted polyester in both the super cotton-like polyester fiber and the linen-like slub yarn is 3%.

[0059] A method for preparing elastic cotton-linen-like polyester fiber, applied to the above-mentioned elastic cotton-linen-like polyester fiber, includes the following steps: S1: By weight, thermoplastic polyester elastomer, polypropylene terephthalate, epoxy dynamic vulcanized elastomer and antioxidant are melt-blended, granulated and dried to obtain skin-blended granules; The melt blending process uses a twin-screw extruder with an extrusion temperature of 225℃, and the drying temperature after granulation is 110℃.

[0060] S2: By weight, the copolymer polyphenylene sulfide, polytetrafluoroethylene micro powder and ethylene-methyl acrylate-glycidyl methacrylate terpolymer are melt-blended, granulated and dried to obtain core layer blended granules; The melt blending process was carried out using a twin-screw extruder with an extrusion temperature of 265℃. The drying temperature after granulation was 130℃, the drying vacuum degree was ≤-0.08MPa, and the moisture content after drying was ≤50ppm.

[0061] S3: Using a core-sheath composite melt spinning equipment, the sheath blended granules and the core blended granules are melted separately and then extruded through a core-sheath composite spinneret to form core-sheath structured nascent fibers. After cooling, oiling, two-stage hot stretching and low-temperature annealing, the core yarn is obtained. The extrusion process included a sheath extrusion temperature of 230℃, a core extrusion temperature of 270℃, a spinneret temperature of 235℃, a spinning speed of 1200m / min, a cooling air temperature of 25℃, an air velocity of 0.6m / s, a relative humidity of 75%, an oil concentration of 3.5%, two-stage hot drawing with the first stage at 100℃ for a draw of 3.2 times and the second stage at 120℃ for a draw of 1.6 times, a low-temperature annealing temperature of 125℃, and an annealing time of 60 seconds.

[0062] S4: Apply a maleic anhydride-grafted polyolefin coating to the surface of the core yarn online, and obtain the coated core yarn after drying; The process of applying the maleic anhydride-grafted polyolefin coating involves immersing the core yarn in a 2.5% (by mass) maleic anhydride-grafted polyolefin aqueous emulsion for 5 seconds, followed by drying at 90°C.

[0063] S5: Using coated core yarn as core yarn, super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound around the outside of core yarn in opposite directions to obtain wound composite fiber; During spiral winding, the super-imitation cotton polyester fiber is wound in the S direction, and the imitation linen slub yarn is wound in the Z direction. The winding density is 1100T / m and the winding tension is 15cN.

[0064] S6: The wound composite fiber is hot-pressed and cross-linked under heating and pressure to obtain elastic cotton-linen-like polyester fiber.

[0065] The hot-press cross-linking and setting temperature is 130℃, the pressure is 0.6MPa, and the processing time is 3 minutes.

[0066] Example 3: This example differs from Example 1 above in that: An elastic cotton-linen-like polyester fiber includes a core yarn and a spiral wound layer spirally wound around the outside of the core yarn. The core yarn has a core-sheath composite structure, and the sheath layer is composed of the following components in parts by weight: 45 parts of thermoplastic polyester elastomer, 25 parts of polypropylene terephthalate, 5 parts of epoxy-modified dynamic vulcanized elastomer, and 0.2 parts of antioxidant. The core layer is composed of the following components in parts by weight: 8 parts of copolymerized polyphenylene sulfide, 3 parts of polytetrafluoroethylene micro powder, and 0.5 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer. The surface of the core yarn is coated with a maleic anhydride-grafted polyolefin coating. The spiral wound layer is formed by spirally wound ultra-cotton-like polyester fiber and linen-like slub yarn in opposite directions around the outside of the core yarn. Both the ultra-cotton-like polyester fiber and the linen-like slub yarn contain polyethylene terephthalate and glycidyl methacrylate-grafted polyester.

[0067] The copolyphenylene sulfide is a copolymer of dichlorobenzene, isophthalic acid and sodium sulfide, with a molar ratio of 1:0.15:1.05. The melting point of the copolyphenylene sulfide is 235℃. The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0068] The mass ratio of the sheath to the core layer of the core yarn is 3:1. The polytetrafluoroethylene micro powder in the core layer forms a nanofiber network in situ. The copolymer polyphenylene sulfide dispersed phase in the core layer is in the form of nanofibers oriented along the fiber axis. The mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is 5%.

[0069] The thickness of the maleic anhydride-grafted polyolefin coating is 0.5 μm, and the mass fraction of glycidyl methacrylate-grafted polyester in both the super cotton-like polyester fiber and the linen-like slub yarn is 2%.

[0070] A method for preparing elastic cotton-linen-like polyester fiber, applied to the above-mentioned elastic cotton-linen-like polyester fiber, includes the following steps: S1: By weight, thermoplastic polyester elastomer, polypropylene terephthalate, epoxy dynamic vulcanized elastomer and antioxidant are melt-blended, granulated and dried to obtain skin-blended granules; The melt blending process uses a twin-screw extruder with an extrusion temperature of 190℃, and the drying temperature after granulation is 100℃.

[0071] S2: By weight, the copolymer polyphenylene sulfide, polytetrafluoroethylene micro powder and ethylene-methyl acrylate-glycidyl methacrylate terpolymer are melt-blended, granulated and dried to obtain core layer blended granules; The melt blending process was carried out using a twin-screw extruder at an extrusion temperature of 230℃. The drying temperature after granulation was 120℃, the drying vacuum degree was ≤-0.08MPa, and the moisture content after drying was ≤50ppm.

[0072] S3: Using a core-sheath composite melt spinning equipment, the sheath blended granules and the core blended granules are melted separately and then extruded through a core-sheath composite spinneret to form core-sheath structured nascent fibers. After cooling, oiling, two-stage hot stretching and low-temperature annealing, the core yarn is obtained. The extrusion process included a sheath extrusion temperature of 200℃, a core extrusion temperature of 240℃, a spinneret temperature of 230℃, a spinning speed of 900m / min, a cooling air temperature of 20℃, an air velocity of 0.4m / s, a relative humidity of 65%, an oil concentration of 2.5%, two-stage hot drawing with the first stage at 90℃ for a draw of 2.8 times and the second stage at 110℃ for a draw of 1.4 times, a low-temperature annealing temperature of 120℃, and an annealing time of 30 seconds.

[0073] S4: Apply a maleic anhydride-grafted polyolefin coating to the surface of the core yarn online, and obtain the coated core yarn after drying; The process of applying the maleic anhydride-grafted polyolefin coating involves immersing the core yarn in a 2.0% (by mass) maleic anhydride-grafted polyolefin aqueous emulsion for 2 seconds, and then drying it at 80°C.

[0074] S5: Using coated core yarn as core yarn, super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound around the outside of core yarn in opposite directions to obtain wound composite fiber; In the spiral winding process, the super imitation cotton polyester fiber is wound in the S direction, and the imitation linen slub yarn is wound in the Z direction. The winding density is 900T / m and the winding tension is 10cN.

[0075] S6: The wound composite fiber is hot-pressed and cross-linked under heating and pressure to obtain elastic cotton-linen-like polyester fiber.

[0076] The hot-press cross-linking and setting temperature is 120℃, the pressure is 0.4MPa, and the processing time is 2 minutes.

[0077] Comparative Example 1: An elastic cotton-linen-like polyester fiber, comprising a core yarn and super cotton-like polyester fiber and linen-like slub yarn wound around the outside of the core yarn; the super cotton-like polyester fiber and linen-like slub yarn are spirally wound around the outside of the core yarn in opposite directions; the core yarn comprises spandex filaments and Sorona fiber yarns twisted together.

[0078] The spandex filament has a fineness of 40~70D, and the Sorona fiber yarn has a fineness of 75~150D. The mass ratio of spandex filament to Sorona fiber yarn is 1:1~1:2. The super cotton-like polyester fiber has a hollow structure with a hollowness of 30%~40% and a single filament fineness of 1.5~3dtex; the linen-like slub yarn has a twist of 1200~1600T / m and a single filament fineness of 2~4dtex.

[0079] A method for preparing elastic cotton-linen-like polyester fiber includes the following steps: S1: Spandex filament and Sorona fiber yarn are twisted together at a mass ratio of 1:1 to 1:2, with a twist of 800 to 1200 T / m, to obtain the core yarn; S2: Super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound on the outside of the core yarn in opposite directions. The super imitation cotton polyester fiber is wound in the S direction and the imitation linen slub yarn is wound in the Z direction. The winding density is 800~1200T / m and the winding tension is 10~20cN to obtain the wound composite fiber. S3: Heat-set the wound composite fiber at 80~100℃ for 30~60 minutes to obtain elastic cotton-linen-like polyester fiber.

[0080] The spandex filament is a polyurethane elastic fiber, and the Sorona fiber yarn is a polypropylene terephthalate fiber.

[0081] Comparative Example 2: This comparative example differs from Example 1 above in that: The core layer of the core yarn does not contain polytetrafluoroethylene powder, and the rest is the same as in Example 1.

[0082] Comparative Example 3: This comparative example differs from Example 1 above in that: The core layer of the core yarn does not contain copolyphenylene sulfide, and the rest is the same as in Example 1.

[0083] Comparative Example 4: This comparative example differs from Example 1 above in that: No epoxy-based dynamically vulcanized elastomer is added to the outer layer of the core yarn; otherwise, it is the same as in Example 1.

[0084] Comparative Example 5: This comparative example differs from Example 1 above in that: The core yarn surface is not coated with maleic anhydride-grafted polyolefin, i.e. step S4 is omitted, and the rest is the same as in Example 1.

[0085] Comparative Example 6: This comparative example differs from Example 1 above in that: The temperature for hot-press crosslinking and setting was 90°C, the pressure was 0.5 MPa, and the processing time was 2.5 minutes. The rest was the same as in Example 1.

[0086] Comparative Example 7: This comparative example differs from Example 1 above in that: The winding layer does not contain glycidyl methacrylate grafted polyester, that is, the super cotton-like polyester fiber is composed solely of polyethylene terephthalate, and the linen-like slub yarn is composed solely of polyethylene terephthalate. The rest is the same as in Example 1.

[0087] Performance testing: The elastic cotton-linen-like polyester fibers prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to the following performance tests: Elastic recovery rate: The test was conducted according to GB / T 14344-2008 "Test Method for Tensile Properties of Chemical Fiber Filaments". The elastic recovery rate was tested in the initial state, after 100 tensile cycles, and after 200 tensile cycles. The tensile elongation was set at 30%. Anti-slip property: The fiber was made into a standard sample and tested according to GB / T 13772.1-2008 "Determination of anti-slip property of yarn at seam of woven fabric - Part 1: constant slip method". The axial slip of the winding layer after 50 standard washes was recorded. Tensile strength: The tensile strength of the fiber was tested in accordance with GB / T 14344-2008.

[0088] Elongation at break: The elongation at break of the fiber was tested in accordance with GB / T 14344-2008. Limiting oxygen index: The limiting oxygen index of the fiber is tested according to GB / T 5454-1997 "Test for flammability of textiles - oxygen index method". The test results are shown in Table 1.

[0089] Table 1

[0090] As can be seen from Examples 1 to 3 and Comparative Examples 1 to 7, and Table 1, this application achieves a comprehensive improvement in fiber elasticity retention after repeated stretching, anti-slip properties of the winding layer, breaking strength, and flame retardant properties through the synergistic reinforcement of polytetrafluoroethylene micropowder and copolyphenylene sulfide in the core yarn of the core-sheath composite structure, the interfacial compatibilization of the epoxy dynamic vulcanized elastomer in the sheath layer, the chemical cross-linking anchoring of the maleic anhydride-grafted polyolefin coating on the core yarn surface and the glycidyl methacrylate-grafted polyester in the winding layer, and a suitable hot pressing and setting temperature.

[0091] As can be seen from Example 1, Comparative Examples 2 and 3, and Table 1, the combination of polytetrafluoroethylene micropowder and copolyphenylene sulfide in the core layer can form a composite reinforcement structure of nanofiber network and axially oriented fibers. This allows them to synergistically bear stress during repeated stretching, inhibit the rapid accumulation of elastic fatigue, and reduce the expansion of micro-damage inside the core yarn, thereby improving the elasticity and durability of the fiber.

[0092] As can be seen from Example 1 and Comparative Example 4, and Table 1, the addition of epoxy-based dynamic vulcanized elastomer to the skin layer can improve the interfacial compatibility between thermoplastic polyester elastomer and copolyphenylene sulfide, so that the rigid component is uniformly dispersed in the elastic matrix, avoiding stress concentration and elastic decay caused by interfacial debonding, thereby maintaining the elastic recovery ability of the fiber after multiple stretching.

[0093] As can be seen from Example 1, Comparative Examples 5 and 7, and Table 1, the maleic anhydride-grafted polyolefin coating on the core yarn surface and the glycidyl methacrylate-grafted polyester in the winding layer together constitute a reactive interface system, thereby undergoing a chemical cross-linking reaction under hot pressing conditions to form covalent bonds for anchoring, enhancing the bonding strength between the core yarn and the winding layer, and thus reducing the axial slippage of the winding layer during washing and stretching.

[0094] As can be seen from Example 1 and Comparative Example 6 and Table 1, the temperature of hot-press crosslinking and setting can affect the degree of interfacial chemical reaction. This application can ensure that the ring-opening addition reaction between maleic anhydride-grafted polyolefin and glycidyl methacrylate-grafted polyester is fully carried out to form a stable crosslinking network. However, when the temperature is too low, the crosslinking reaction is incomplete and the interfacial anchoring effect decreases.

[0095] 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. An elastic cotton-linen-like polyester fiber, characterized in that, The device comprises a core yarn and a spiral wound layer wound around the outside of the core yarn. The core yarn has a core-sheath composite structure, and the sheath layer is composed of the following components in parts by weight: 45-55 parts of thermoplastic polyester elastomer, 25-35 parts of polypropylene terephthalate, 5-8 parts of epoxy-based dynamically vulcanized elastomer, and 0.2-0.5 parts of antioxidant. The core layer is composed of the following components in parts by weight: 8-12 parts of copolymerized polyphenylene sulfide, 3-6 parts of polytetrafluoroethylene micro powder, and 0.5-1.0 parts of ethylene-methyl acrylate-glycidyl methacrylate terpolymer. The surface of the core yarn is coated with a maleic anhydride-grafted polyolefin coating. The spiral wound layer is formed by spirally wound in opposite directions around the outside of the core yarn with ultra-cotton-like polyester fiber and imitation linen slub yarn. Both the ultra-cotton-like polyester fiber and the imitation linen slub yarn contain polyethylene terephthalate and glycidyl methacrylate-grafted polyester.

2. The elastic cotton-linen-like polyester fiber according to claim 1, characterized in that: The copolymerized polyphenylene sulfide is a copolymer of dichlorobenzene, isophthalic acid and sodium sulfide, with a molar ratio of 1:0.15~0.25:1.05~1.10, and the melting point of the copolymerized polyphenylene sulfide is 235~245℃; the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

3. The elastic cotton-linen-like polyester fiber according to claim 1, characterized in that: The mass ratio of the sheath to the core layer of the core yarn is 3~4:

1. The polytetrafluoroethylene micro powder of the core layer forms a nanofiber network in situ. The copolymer polyphenylene sulfide dispersed phase of the core layer is in the form of nanofibers oriented along the fiber axis. The mass fraction of glycidyl methacrylate in the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is 5%~8%.

4. The elastic cotton-linen-like polyester fiber according to claim 1, characterized in that: The thickness of the maleic anhydride-grafted polyolefin coating is 0.5~1.5μm, and the mass fraction of glycidyl methacrylate-grafted polyester in the super cotton-like polyester fiber and the hemp-like slub yarn is 2%~3%.

5. A method for preparing elastic cotton-linen-like polyester fiber, characterized in that: The application of the elastic cotton-linen-like polyester fiber according to any one of claims 1-4 includes the following steps: S1: By weight, thermoplastic polyester elastomer, polypropylene terephthalate, epoxy dynamic vulcanized elastomer and antioxidant are melt-blended, granulated and dried to obtain skin-blended granules; S2: By weight, the copolymer polyphenylene sulfide, polytetrafluoroethylene micro powder and ethylene-methyl acrylate-glycidyl methacrylate terpolymer are melt-blended, granulated and dried to obtain core layer blended granules; S3: Using a core-sheath composite melt spinning equipment, the sheath blended granules and the core blended granules are melted separately and then extruded through a core-sheath composite spinneret to form core-sheath structured nascent fibers. After cooling, oiling, two-stage hot stretching and low-temperature annealing, the core yarn is obtained. S4: Apply a maleic anhydride-grafted polyolefin coating to the surface of the core yarn online, and obtain the coated core yarn after drying; S5: Using coated core yarn as core yarn, super imitation cotton polyester fiber and imitation linen slub yarn are spirally wound around the outside of core yarn in opposite directions to obtain wound composite fiber; S6: The wound composite fiber is hot-pressed and cross-linked under heating and pressure to obtain elastic cotton-linen-like polyester fiber.

6. The method for preparing elastic cotton-linen-like polyester fiber according to claim 6, characterized in that: In step S1, the melt blending is performed using a twin-screw extruder with an extrusion temperature of 190~225℃, and the drying temperature after granulation is 100~110℃. In step S2, the melt blending is performed using a twin-screw extruder with an extrusion temperature of 230~265℃. The drying temperature after granulation is 120~130℃, the drying vacuum degree is ≤-0.08MPa, and the moisture content after drying is ≤50ppm.

7. The method for preparing elastic cotton-linen-like polyester fiber according to claim 6, characterized in that: In step S3, the extrusion temperature of the outer layer is 200~230℃, the extrusion temperature of the core layer is 240~270℃, the spinneret temperature is 230~235℃, the spinning speed is 900~1200m / min, the cooling air temperature is 20~25℃, the air speed is 0.4~0.6m / s, the relative humidity is 65%~75%, the oil concentration of the oiling agent is 2.5%~3.5%, the two-stage hot drawing is 2.8~3.2 times at 90~100℃ for the first stage and 1.4~1.6 times at 110~120℃ for the second stage, and the low-temperature annealing temperature is 120~125℃ for 30~60 seconds.

8. The method for preparing elastic cotton-linen-like polyester fiber according to claim 6, characterized in that: In step S4, the application of the maleic anhydride-grafted polyolefin coating is performed by immersing the core yarn in a maleic anhydride-grafted polyolefin aqueous emulsion with a mass fraction of 2.0% to 2.5% for 2 to 5 seconds, and then drying it at 80 to 90°C.

9. The method for preparing elastic cotton-linen-like polyester fiber according to claim 6, characterized in that: In step S5, the spiral winding direction of the super cotton-like polyester fiber is S-direction, and the winding direction of the linen-like slub yarn is Z-direction. The winding density is 900~1100T / m and the winding tension is 10~15cN.

10. The method for preparing elastic cotton-linen-like polyester fiber according to claim 6, characterized in that: In step S6, the temperature for hot-press cross-linking and shaping is 120~130℃, the pressure is 0.4~0.6MPa, and the processing time is 2~3 minutes.

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