Fiber material for sunscreen creep-resistant fabric and preparation method of fiber material

Abstract

The invention belongs to the technical field of polymer fiber materials, and particularly relates to a fiber material for sunscreen creep-resistant fabric and a preparation method of the fiber material. The fiber material provided by the invention takes regenerated PET as a matrix, has a core-sheath composite structure, and comprises a skeleton component composed of creep-resistant regenerated PET and a functional component composed of regenerated PET containing a reactive ultraviolet light absorber. The preparation method specifically comprises the following steps: blending an ultraviolet light absorber with an epoxy group, a compatilizer and regenerated PET, and blending a creep resistant agent and regenerated PET to prepare reactive ultraviolet light absorption master batches and creep resistant master batches; blending, melting and spinning regenerated PET slices with different viscosities, the reactive ultraviolet absorption master batch and the creep-resistant master batch to form a first component spinning melt and a second component spinning melt; extruding through a bi-component composite spinning spinneret plate to form a core-sheath structured as-spun fiber with a special-shaped cross section; and carrying out on-line crosslinking, drafting and relaxation heat setting treatment to prepare the fiber with excellent sun-proof and creep-resistant properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer fiber material technology, specifically relating to a fiber material used in sun-protective and creep-resistant fabrics and its preparation method. Background Technology

[0002] With the increasing demand for outdoor activities and special occupational protection, there is a growing need for fabrics that combine sun protection (UV protection) and durability (creep resistance). CN215882907U discloses a sun-protective fabric that uses reflective yarns to reflect light and prevent it from passing through the fabric, and light-absorbing yarns to absorb light and trap it in the sun-protective layer. However, after repeated washing and use, the sun protection effect gradually weakens or even disappears, and its durability is poor.

[0003] Currently, the main technologies for imparting sun protection to fabrics have significant shortcomings: the inorganic or organic UV absorbers added by the blending method have weak bonding with the matrix resin, and are prone to migration and loss during long-term use, washing and friction, resulting in a rapid decline in sun protection function; the finishing method affects the fabric's feel and breathability, and the coating is prone to cracking or even peeling off due to fabric creep and bending.

[0004] More importantly, existing technologies generally neglect the creep resistance of the fiber material itself. Creep refers to the plastic deformation of a material over time under sustained stress below its yield strength. For outdoor tents, awnings, workwear, and close-fitting sportswear that are under tension for extended periods, fabric creep can lead to fabric loosening and deformation, affecting not only appearance and dimensional stability but also the uniformity of sunscreen distribution or the integrity of the surface sunscreen coating, becoming a fatal weakness in the durability of sun protection. Therefore, developing a technology that combines sun protection functionality with creep-resistant structure at the fiber level is key to achieving long-lasting, high-performance fabrics. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor durability of UV protection and severe fiber creep deformation in existing sun-protective fabrics, and to provide a sun-protective and creep-resistant fiber material based on recycled PET and its preparation method. The fiber material of this invention consists of a core component and a sheath component of a recycled PET matrix, forming a two-component composite fiber with an irregularly shaped cross-section. The core component contains recycled PET and an anti-creep agent, while the sheath component contains recycled PET and a UV absorber with epoxy groups. This fiber material significantly improves creep resistance while enhancing UV protection performance, ensuring that fabrics made from this fiber maintain good sun protection effects during long-term use.

[0006] A fiber material for use in sun-protective and creep-resistant fabrics and its preparation method are described below: S1: 4-6 parts by weight of benzotriazole UV absorber with epoxy groups, 1.5-2.5 parts by weight of epoxy compatibilizer glycidyl methacrylate copolymer, and 80-90 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g are blended and extruded in a twin-screw extruder, then cooled with water and pelletized to obtain reactive UV absorption masterbatch. 5-6 parts by weight of anti-creep agent and 80-90 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g are blended and extruded, then cooled with water and pelletized to obtain anti-creep masterbatch. S2: Dry the recycled PET chips; take 80-90 parts of dried PET chips with an intrinsic viscosity of 0.85 dL / g and mix with 1-2 parts of anti-creep masterbatch, and melt blend through a single-screw extruder to obtain the first component spinning melt; take 80-90 parts of dried PET chips with an intrinsic viscosity of 0.65 dL / g and mix with 8-12 parts of reactive UV-absorbing masterbatch, add 0.1-0.2 parts of nickel chelate UV quencher and 0.05-0.15 parts of hindered phenolic antioxidant. The mixture is thoroughly mixed and fed into another single-screw extruder for melting, yielding the second component spinning melt. The temperature of both melt streams is controlled at 270–275°C. Spinning is performed using a core-sheath composite spinning assembly with 36 orifices in the spinneret, each orifice having a diameter of 0.3 mm and designed as a trilobal or cross-shaped core-sheath structure. The output ratio of the first and second components is controlled at 4:6 by a metering pump. The melt is extruded through the spinneret, cooled and solidified, and spun at a speed of 1000 m / min to obtain nascent fiber bundles. S3: The nascent fiber bundle is placed in an online ultraviolet light activation channel for online cross-linking, and then enters an online heat annealing channel. The fiber bundle is treated in a relaxed state at 120°C for 3 seconds using hot air circulation. Finally, it is cooled and cured with 20°C cooling air, and then a spinning oil is applied to obtain the fiber bundle. S4: The fiber bundle is subjected to two-stage thermal stretching, and the stretched fibers are subjected to relaxation heat setting treatment to obtain the fiber material of the present invention.

[0007] Furthermore, the ultraviolet absorber with epoxy groups described in step S1 is selected as benzotriazole grafted with glycidyl methacrylate.

[0008] Furthermore, in the extruder described in step S1, the temperature is set to 250-260°C for the feeding section, 260-270°C for the homogenization section, 265-275°C for the metering section, and 270-280°C for the die head.

[0009] Furthermore, the drying described in step S2 specifically involves vacuum drying at 135°C for 8 hours.

[0010] Furthermore, the anti-creep agent described in step S2 is selected from nano-silica, montmorillonite, or carbon nanotubes.

[0011] Furthermore, the online crosslinking described in step S3 specifically uses UVA ultraviolet light with a wavelength of 365 nm and an irradiance of 80 mW / cm². 2 Irradiate for 1 to 1.5 seconds.

[0012] Furthermore, the two-stage hot stretching described in step S4 specifically involves stretching the first stretching zone at 1.5 times the stretching ratio on a first hot roller at 85°C and stretching the second stretching zone at 125°C on a second hot roller, so that the total stretching ratio reaches 3.0 times.

[0013] Furthermore, the relaxation heat setting treatment described in step S4 specifically involves placing the product in a heat setting chamber at 160–170°C and treating it in a relaxed state for 10–15 minutes.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The reactive ultraviolet absorber in the fiber sheath of the present invention is fixed on the polymer chain by chemical bonds, which greatly improves the durability of the ultraviolet absorber in the fiber and makes it less prone to migration, loss or thermal degradation; the sun protection function is long-lasting.

[0015] (2) The core layer of the fiber of the present invention contains an anti-creep agent and is cross-linked and reinforced, which significantly reduces the creep deformation of the fiber under continuous stress and high temperature conditions and has excellent anti-creep performance.

[0016] (3) The present invention adopts a dual-component core-sheath / parallel structure to arrange the sun protection component and the anti-creep component in different regions of the fiber, so as to achieve synergistic effect; the sheath layer is rich in functional additives but does not directly bear the force, reducing the weakening of the existing mechanical properties of the fiber body by the additives; the core layer provides strength support and protects the functional substances inside the sheath layer, thereby improving the overall performance of the fiber.

[0017] (4) This invention uses recycled PET as the main raw material to realize the high-value utilization of waste plastics, which is in line with the development direction of circular economy and green environmental protection, and is environmentally sustainable. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of fiber materials for sun-protective and creep-resistant fabrics according to the present invention.

[0019] Figure 2 The infrared spectrum is from Experiment Example 1.

[0020] Figure 3 This is a scanning electron microscope image of the test in Experiment Example 2.

[0021] Figure 4 This is a comparison chart of the UPF retention rate and creep strain rate test results after water washing in Experiment Example 3. Detailed Implementation

[0022] The following embodiments further explain and illustrate the technical solutions of the present invention. It is particularly noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention. Figure 1 The diagram shows a manufacturing process for a fiber material used in sun-protective and creep-resistant fabrics. The detailed manufacturing steps are as follows: 1. Preparation of reactive UV-absorbing masterbatch and anti-creep masterbatch A reactive UV-absorbing masterbatch is prepared by melt-blending an epoxy-containing UV absorber, a compatibilizer, and recycled PET chips in a twin-screw extruder; an anti-creep agent is blended and extruded with recycled PET chips, then water-cooled and pelletized to obtain an anti-creep masterbatch.

[0023] This is a reactive compatibilization and pre-dispersion process. The reactive UV absorber, with epoxy groups in its molecule, can covalently bond with the polyester matrix, thus solidifying onto the polymer chain during fiber formation. The functional auxiliaries are pre-dispersed and anchored in the carrier resin, forming a high-concentration, high-stability functional masterbatch, avoiding problems such as agglomeration and spinning breakage that easily occur when added directly later. This lays the chemical foundation for in-situ crosslinking in subsequent spinning steps.

[0024] 2. Melt preparation and composite spinning The first skeletal melt and the second functional component melt were prepared separately, and then spun into a core-sheath composite fiber using a special spinneret and cooled to form the final fiber. The first component uses high-viscosity recycled PET, whose high molecular weight results in higher melt strength and a high modulus in the final fiber, forming the skeletal basis for creep resistance. The second component uses standard-viscosity recycled PET, which has better flowability and is beneficial for the melt dispersion of the functional masterbatch and subsequent crosslinking reactions. Anti-creep agents can be selected from nano-silica, montmorillonite, and carbon nanotubes; these agents effectively improve the creep resistance of recycled PET fibers through different physical mechanisms. Nano-silica acts as a physical crosslinking point, restricting the slippage of PET molecular chains through hydrogen bonds / van der Waals forces. Montmorillonite's layered structure is dispersed and peeled away in the PET matrix, forming a maze effect that physically hinders molecular chain movement. Carbon nanotubes' large aspect ratio allows them to construct a three-dimensional network structure, strongly mechanically locking the molecular chains.

[0025] By employing a cross-shaped or trilobal cross-section, the fiber surface area is increased, and its grooved and angular structure can generate multiple specular reflections and scatterings of incident light, providing the first physical sun protection barrier. The core-sheath structure is designed so that the functional components carrying ultraviolet absorbers dominate the fiber surface layer, directly blocking ultraviolet rays. The high-modulus core layer provides tensile and deformation resistance support. The two components are tightly bonded at the interface, ensuring that the functional layer and structural layer work together during deformation and are not easily peeled off.

[0026] 3. Online activation and annealing The nascent fiber bundles are first passed through an online ultraviolet light activation channel that emits UVA band ultraviolet light with a main wavelength of 365nm. This process utilizes the high energy of ultraviolet light to specifically excite the epoxy groups in the functional masterbatch, causing them to generate active sites and creating conditions for subsequent cross-linking reactions.

[0027] Subsequently, the UV-activated fiber bundles immediately enter an online thermal annealing tunnel. This tunnel uses a hot air circulation annealing method, which provides the necessary heat energy to promote the reaction between the activated epoxy groups and the carboxyl or hydroxyl groups at the ends of the PET molecular chains, forming a strong chemical cross-linking network. At the same time, this heat treatment can effectively eliminate the internal stress generated in the fibers during high-speed spinning, realizing the relaxation and reconstruction of the molecular chains, thereby significantly improving the dimensional stability and creep resistance of the fibers. Finally, the activated-annealed fiber bundles are cooled and solidified by cooling air and uniformly coated with spinning oil.

[0028] 4. Stretching and relaxation heat setting The filament bundle undergoes two stages of thermal stretching followed by relaxation and heat setting.

[0029] Two-stage thermal stretching of fibers above the glass transition temperature orients disordered molecular chains along the fiber axis and promotes crystallization, significantly improving the fiber's breaking strength, modulus, and fatigue resistance. Relaxation heat setting of the fibers at a temperature above the glass transition temperature but below the melting point allows for moderate disorientation and rearrangement of the oriented molecular chain segments, eliminating internal stress and stabilizing the crystalline structure, thus achieving the required strength imparted by stretching. Relaxation heat setting is crucial for achieving low creep, minimizing internal stress and forming a stable crystalline network. This relaxed, stable state significantly reduces the tendency for molecular chain slippage and deformation when facing continuous stress during subsequent use, resulting in excellent dimensional stability and creep resistance, ensuring the long-lasting, undeformed carrier of sun protection.

[0030] Example 1 Table 1 Raw Material Information Table A fiber material for use in sun-protective and creep-resistant fabrics and its preparation method, the preparation steps of which are as follows: S1: 5 parts by weight of benzotriazole grafted with glycidyl methacrylate, 2 parts by weight of epoxy compatibilizer glycidyl methacrylate copolymer, and 85 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g were blended and fed into a twin-screw extruder for extrusion. The temperature was set to 255℃ in the feeding section, 265℃ in the homogenization section, 270℃ in the metering section, and 275℃ in the die head. The mixture was then water-cooled and pelletized to obtain a reactive UV-absorbing masterbatch. 5.5 parts by weight of anti-creep agent and 85 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g were blended and extruded, then water-cooled and pelletized to obtain an anti-creep masterbatch. S2: Recycled PET chips are vacuum dried at 135℃ for 8 hours; 85 parts of dried PET chips with an intrinsic viscosity of 0.85 dL / g are mixed with 1.5 parts of nano-silica anti-creep masterbatch and melt-blended using a single-screw extruder to obtain the first component spinning melt; 85 parts of dried PET chips with an intrinsic viscosity of 0.65 dL / g are mixed with 10 parts of reactive UV-absorbing masterbatch, 0.15 parts of nickel chelate UV quencher, and 0.1 parts of hindered phenolic antioxidant are added and mixed evenly, then fed into another... A single-screw extruder melts the material to obtain the second component of the spinning melt; the temperature of both melt streams is controlled at 273℃; a core-sheath composite spinning assembly is used for spinning, with 36 orifices in the spinneret, each orifice having a diameter of 0.3mm and a three-lobed core-sheath structure; the output ratio of the first and second components is controlled at 4:6 by a metering pump; after the melt is extruded through the spinneret, it forms a fine fiber stream, which is then cooled and solidified into nascent fibers by air cooling, and pulled by a high-speed traction roller at a spinning speed of 1000m / min to obtain nascent fiber bundles; S3: The nascent fiber bundle is placed in an online ultraviolet light activation channel for online crosslinking. The ultraviolet light is in the UVA band with a wavelength of 365nm and an irradiation intensity of 80mW / cm². 2 Irradiate for 1.2 seconds, then enter the online hot annealing tunnel, use hot air circulation to treat the fiber bundle at 120°C in a relaxed state for 3 seconds, and finally cool and solidify with 20°C cooling air, and apply spinning oil to obtain the fiber bundle; S4: The fiber bundle is subjected to two-stage hot stretching. The first stretching zone is stretched on a first hot roller at 85°C with a stretching ratio of 1.5 times, and the second stretching zone is stretched on a second hot roller at 125°C, so that the total stretching ratio reaches 3.0 times. The stretched fiber enters a heat setting box at 165°C and is treated in a relaxed state for 12 minutes to obtain the fiber material of the present invention.

[0031] Example 2 The preparation method is the same as in Example 1. However, the difference is: In step S1: 4 parts of glycidyl methacrylate-grafted benzotriazole, 1.5 parts of epoxy-compatible glycidyl methacrylate copolymer, and 80 parts of recycled PET chips with an intrinsic viscosity of 0.65 dL / g; the temperature is set to 250℃ for the feeding section, 260℃ for the homogenization section, 265℃ for the metering section, and 270℃ for the die head; 5 parts of montmorillonite anti-creep agent and 80 parts of recycled PET chips with an intrinsic viscosity of 0.65 dL / g are co-extruded. In step S2: 80 parts of dried PET chips with an intrinsic viscosity of 0.85 dL / g are mixed with 1 part of montmorillonite anti-creep masterbatch; 80 parts of dried PET chips with an intrinsic viscosity of 0.65 dL / g are mixed with 8 parts of reactive UV-absorbing masterbatch, 0.1 parts of nickel chelate UV quencher, and 0.05 parts of hindered phenolic antioxidant are added and mixed evenly; the temperature is controlled at 270℃; each channel is designed with a cross-shaped core-sheath structure; In step S3: the fiber is irradiated in the tunnel for 1 second; In step S4: the stretched fibers are placed in a heat setting chamber at 160°C and treated in a relaxed state for 15 minutes.

[0032] Example 3 The preparation method is the same as in Example 1. However, the difference is: In step S1: 6 parts of glycidyl methacrylate-grafted benzotriazole, 2.5 parts of epoxy-compatible glycidyl methacrylate copolymer, and 90 parts of recycled PET chips with an intrinsic viscosity of 0.65 dL / g; the temperature is set as follows: feeding section 260℃, homogenization section 270℃, metering section 275℃, and die head 280℃; 6 parts of carbon nanotube anti-creep agent and 90 parts of recycled PET chips with an intrinsic viscosity of 0.65 dL / g are co-extruded, then water-cooled and pelletized to obtain carbon nanotube anti-creep masterbatch. In step S2: 90 parts of dried PET chips with an intrinsic viscosity of 0.85 dL / g are mixed with 2 parts of carbon nanotube anti-creep masterbatch; 90 parts of dried PET chips with an intrinsic viscosity of 0.65 dL / g are mixed with 12 parts of reactive UV-absorbing masterbatch, 0.2 parts of nickel chelate UV quencher, and 0.15 parts of hindered phenolic antioxidant are added and mixed evenly; the temperature is controlled at 275℃. In step S3: the fiber is irradiated in the tunnel for 1.5 seconds; In step S4: the stretched fibers are placed in a heat setting chamber at 170°C and treated in a relaxed state for 10 minutes.

[0033] Comparative Example 1 The preparation method is the same as in Example 1. However, in step S1, instead of using an ultraviolet absorber with an epoxy group, an equal amount of a common benzotriazole ultraviolet absorber is used. The remaining steps are the same.

[0034] Comparative Example 2 The preparation method is the same as in Example 1. However, in step S2, core-sheath composite spinning is not used. Instead, all the raw materials of the first and second components in Example 1 are blended and melt-spun using a single-screw extruder to prepare single-component fibers; the total material ratio remains the same as in Example 1. All other steps are the same.

[0035] Comparative Example 3 The preparation method is the same as in Example 1, except that the online activation and annealing in step S3 are omitted; the nascent fibers are directly subjected to hot stretching and heat setting after cooling and oiling. The remaining steps are the same.

[0036] Experimental Example 1 Fourier transform infrared spectroscopy was performed on the masterbatch prepared in step S1 and the cross-linked fiber prepared in step S3 in Example 1. The spectral range was 4000-500 cm⁻¹. -1 2cm resolution -1 The number of scans was 64; Figure 2 As shown, epoxy ring breathing vibration peaks and ester carbonyl peaks were observed in the FTIR spectrum of the functional masterbatch. After the online UV crosslinking reaction, it can be observed from the spectrum that epoxy ring opening and hydroxyl group formation occurred at 915 cm⁻¹. -1 The disappearance or significant reduction of the peak in the finished fiber (915 cm) -1 The characteristic peaks of epoxy at certain locations should show a significant decrease in intensity or even disappear completely. This is the most direct evidence that the epoxy group participates in chemical reactions and transforms into ether or ester bonds. When the epoxy group reacts with a proton donor (such as a carboxyl group), secondary hydroxyl groups are generated along with the opening of the ring. Therefore, the cross-linked fiber spectrum is in the range of 3200-3600 cm⁻¹. -1 The absorbance in the broad peak region should be increased; this spectrum verifies the effectiveness of GMA grafting, the retention of epoxy group activity, and the successful execution of the UV-initiated crosslinking reaction.

[0037] Experimental Example 2 The fiber material prepared in Example 1 was sliced ​​and polished after resin embedding, and then scanned under an electron microscope using a backscattered electron detector with an accelerating voltage of 5-15 kV and a working distance of 8-12 mm. Figure 3 As shown, the core layer of this invention is made up of nano-silica, and the sheath layer is made up of nickel chelate. Using the BSE mode, imaging can be performed based on the difference in average atomic number. The regions containing heavy elements show brighter contrast in the BSE image, which confirms the spatial distribution of the components.

[0038] Experimental Example 3 The comprehensive properties of the fiber materials used in the sun-protective and creep-resistant fabrics prepared in Examples 1-3 and Comparative Examples 1-3 were determined. UV protection performance test: In accordance with the standard GB / T 18830-2009 "Evaluation of UV protection performance of textiles", the UV protection factor (UPF) of the fabric samples was tested using a UV spectrophotometer; at the same time, in order to evaluate durability, the UPF value was tested again after the samples were washed 50 times with standard water, and the sun protection performance retention rate was calculated. Creep resistance: Following ASTM D 2990-17, "Standard Test Methods for Tensile, Compression and Flexural Creep and Creep Fracture of Plastics," a constant load (30% of the breaking strength) was applied to the monofilament fiber under constant temperature and humidity conditions, and its creep strain rate was tested over 100 hours. The test temperature was set at a high temperature of 70°C to simulate an extreme environment. Tensile strength test: The tensile strength of the fiber was tested in accordance with the national standard GB / T 14344-2008 "Test method for tensile properties of chemical fiber filament".

[0039] The specific test comparison results are shown in Table 2. Figure 4 As shown: Table 2. Comparison of overall performance between Examples 1-3 and Comparative Examples 1-3 The comparison results above show that the ordinary benzotriazole UV absorber in Comparative Example 1 had a lower initial UPF value, and the UPF retention rate after washing was much lower than that in the example. This proves the irreplaceable nature of reactive UV absorbers forming covalent bonds with PET molecular chains through online crosslinking. Ordinary absorbers rely solely on physical dispersion, and migrate and are lost in large quantities during repeated washing, leading to a sharp decline in sun protection function. In Comparative Example 2, the lack of core-sheath composite spinning resulted in poor creep resistance and mechanical strength. The blended spinning disrupted the partitioned design of the core layer bearing capacity and the sheath layer function, causing the creep-resistant agent to disperse throughout the cross-section and fail to form a cohesive layer. The high-strength continuous core skeleton and the interference of functional additives with the orientation and crystallization of the PET matrix lead to a significant decrease in overall strength and low breaking strength. Comparative Example 3, without online activation and annealing treatment, has a low initial UPF value and low UPF retention rate after washing, which affects creep resistance. The omission of the irradiation step means that the epoxy groups on the ultraviolet absorber are not activated and cannot bond with PET, which leads to a decrease in sun protection durability due to the lack of chemical anchoring. The entire fiber, especially the sheath, fails to form an additional cross-linked network, weakening the overall structural integrity and thus affecting creep resistance and breaking strength.

Claims

1. A fiber material for use in sun-protective and creep-resistant fabrics, employing a core-sheath composite structure, characterized in that, The core-sheath composite structure is a two-component composite fiber composed of a core component and a sheath component of a PET matrix, which has an irregular cross-section; the core component is composed of high intrinsic viscosity PET and an anti-creep agent, and the sheath component is composed of standard viscosity PET and an ultraviolet absorber with epoxy groups; the high intrinsic viscosity is 0.85 dL / g, and the standard viscosity is 0.65 dL / g.

2. The fiber material for use in sun-protective and creep-resistant fabrics according to claim 1, characterized in that, The irregular cross-section includes a trefoil shape or a cross shape.

3. The fiber material for use in sun-protective and creep-resistant fabrics according to claim 1, characterized in that, The anti-creep agent is selected from nano-silica, montmorillonite, or carbon nanotubes.

4. The fiber material for use in sun-protective and creep-resistant fabrics according to claim 1, characterized in that, The UV absorber with epoxy groups is selected as benzotriazole grafted with glycidyl methacrylate.

5. A method for preparing a fiber material for a sun-protective and creep-resistant fabric according to any one of claims 1-4, characterized in that, Includes the following steps: S1: 4-6 parts by weight of benzotriazole UV absorber with epoxy groups, 1.5-2.5 parts by weight of epoxy compatibilizer glycidyl methacrylate copolymer, and 80-90 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g are blended and extruded in a twin-screw extruder, then cooled with water and pelletized to obtain reactive UV absorption masterbatch. 5-6 parts by weight of anti-creep agent and 80-90 parts by weight of recycled PET chips with intrinsic viscosity of 0.65 dL / g are blended and extruded, then cooled with water and pelletized to obtain anti-creep masterbatch. S2: Dry the recycled PET chips; take 80-90 parts of dried PET chips with an intrinsic viscosity of 0.85 dL / g and mix with 1-2 parts of anti-creep masterbatch, and melt blend through a single-screw extruder to obtain the first component spinning melt; take 80-90 parts of dried PET chips with an intrinsic viscosity of 0.65 dL / g and mix with 8-12 parts of reactive UV-absorbing masterbatch, add 0.1-0.2 parts of nickel chelate UV quencher and 0.05-0.15 parts of hindered phenolic antioxidant. The mixture is thoroughly mixed and fed into another single-screw extruder for melting, yielding the second component spinning melt. The temperature of both melt streams is controlled at 270–275°C. Spinning is performed using a core-sheath composite spinning assembly with 36 orifices in the spinneret, each orifice having a diameter of 0.3 mm and designed as a trilobal or cross-shaped core-sheath structure. The output ratio of the first and second components is controlled at 4:6 by a metering pump. The melt is extruded through the spinneret, cooled and solidified, and spun at a speed of 1000 m / min to obtain nascent fiber bundles. S3: The nascent fiber bundle is placed in an online ultraviolet light activation channel for online cross-linking, and then enters an online heat annealing channel. The fiber bundle is treated in a relaxed state at 120°C for 3 seconds using hot air circulation. Finally, it is cooled and cured with 20°C cooling air, and then a spinning oil is applied to obtain the fiber bundle. S4: The fiber bundle is subjected to two-stage thermal stretching, and the stretched fibers are subjected to relaxation heat setting treatment to obtain the fiber material of the present invention.

6. The method for preparing a fiber material for a sun-protective and creep-resistant fabric according to claim 5, characterized in that, The extruder described in step S1 has the following temperature settings: feeding section 250-260℃, homogenization section 260-270℃, metering section 265-275℃, and die head 270-280℃.

7. The method for preparing a fiber material for a sun-protective and creep-resistant fabric according to claim 5, characterized in that, The drying process described in step S2 specifically involves vacuum drying at 135°C for 8 hours.

8. A method for preparing a fiber material for a sun-protective and creep-resistant fabric according to claim 5, characterized in that, The online crosslinking described in step S3 uses UVA ultraviolet light with a wavelength of 365 nm and an irradiance of 80 mW / cm². 2 Irradiate for 1 to 1.5 seconds.

9. A method for preparing a fiber material for a sun-protective and creep-resistant fabric according to claim 5, characterized in that, The two-stage hot stretching described in step S4 specifically involves stretching the first stretching zone at 1.5 times the stretching ratio on a first hot roller at 85°C, and stretching the second stretching zone at 125°C on a second hot roller, so that the total stretching ratio reaches 3.0 times.

10. A method for preparing a fiber material for a sun-protective and creep-resistant fabric according to claim 5, characterized in that, The relaxation heat setting process described in step S4 specifically involves placing the product in a heat setting chamber at 160–170°C and processing it in a relaxed state for 10–15 minutes.

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