A far-infrared functional composite material, its preparation method and application

Abstract

This invention discloses a far-infrared functional composite material, its preparation method, and its application, belonging to the field of composite material technology. Specifically, it comprises the following components by weight: 25-35 parts of surface-modified far-infrared functional composite powder and 75-85 parts of composite polymer matrix. This invention optimizes the particle size distribution of the far-infrared functional powder and chemically modifies the powder surface. Then, it uses a composite polymer matrix with rigidity and flexibility to synergistically combine with the surface-modified far-infrared functional composite powder. This not only effectively improves the far-infrared emission performance and mechanical properties of the far-infrared functional composite material, but also improves the thermal dimensional stability and washability of the material.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a far-infrared functional composite material, its preparation method, and its application. Background Technology

[0002] Far-infrared functional materials have received widespread attention in recent years in the fields of functional fibers, thermal insulation fabrics, health protection products, and related composite materials because they can absorb, reflect, or re-radiate the heat energy radiated by the human body. The existing standard GB / T30127-2013 has established a testing and evaluation method for the far-infrared performance of textiles, with far-infrared emissivity and temperature rise performance as the core, and it is applicable to fibers, yarns, fabrics, non-woven fabrics and their products. This also shows that the development and application of far-infrared functional materials in textiles and flexible materials is already quite common.

[0003] Currently, a common technical approach is to directly add far-infrared functional powders such as tourmaline, germanium, zirconium oxide, titanium dioxide, and alumina to a polymer matrix, and then obtain far-infrared materials through melt spinning, coating, padding, or lamination. This can impart far-infrared emission properties to the products to a certain extent. However, due to the significant differences between inorganic functional powders and organic polymer matrices in terms of polarity, surface energy, and interfacial wettability, problems such as powder agglomeration, uneven dispersion, and insufficient interfacial bonding often occur. Especially when the amount of functional powder added increases, the above problems will be further aggravated. It not only affects the effective distribution of far-infrared functional particles in the material, but also easily forms defect points inside the material, which leads to a decrease in mechanical properties, a decrease in processing stability, and damage to the feel and appearance quality of the product. Moreover, for fiber and fabric far-infrared materials, if the functional powder exists only through simple physical blending or surface adhesion, the functional particles are prone to migration, shedding, or interface instability during subsequent use, washing, friction, and heat treatment, resulting in a decrease in far-infrared emissivity and a decrease in dimensional retention, making it difficult to meet the requirements for long-term use.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a far-infrared functional composite material, its preparation method, and its application, so as to solve the technical defects mentioned in the background art.

[0006] The objective of this invention can be achieved through the following technical solution: a far-infrared functional composite material, comprising the following components by weight: 25-35 parts of surface-modified far-infrared functional composite powder and 75-85 parts of composite polymer matrix; The surface-modified far-infrared functional composite powder is obtained by surface modification of far-infrared functional composite powder with hydroxyl-terminated fluorinated polysiloxane. The method for preparing the composite polymer matrix is ​​as follows: Under an inert gas atmosphere, pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, and N,N-dimethylacetamide are mixed and stirred until dissolved. The mixture is stirred at room temperature for 22-24 hours. A polyurethane prepolymer solution is added to the reaction system, and the temperature is raised to 60-70°C. The reaction is maintained at this temperature for 40-50 minutes. Epoxy resin is added to the reaction system, and the mixture is stirred for 30-50 minutes. After post-treatment, the composite polymer matrix is ​​obtained.

[0007] The synthesis reaction formula for the composite polymer matrix is ​​as follows: Further, the ratio of 4,4'-diaminodiphenyl ether, N,N-dimethylacetamide, polyurethane prepolymer solution, and epoxy resin is 1g:10mL:10mL:0.3-0.5g, the ratio of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether is 1mol:1.2mol, the polyurethane prepolymer solution is composed of polyurethane prepolymer and N,N-dimethylacetamide at a ratio of 1g:4-5mL, and the post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, 1wt% sodium dodecyl sulfate solution is added to the reaction system, stirred and dispersed for 30-50min, filtered, the filter cake is washed 3 times with purified water and dried under vacuum, the filter cake is transferred to a drying oven at 80-90℃ and vacuum dried to constant weight to obtain the composite polymer matrix.

[0008] Furthermore, the far-infrared functional composite powder is composed of tourmaline and zircon in a weight ratio of (3-5):1; the far-infrared functional composite powder has a bimodal particle size distribution, with the D50 of the first particle size distribution being 2-5 μm and the D50 of the second particle size distribution being 0.5-1 μm, and the weight ratio of the first particle size distribution to the second particle size distribution being (6-7):(4-3).

[0009] Further, the preparation method of the hydroxyl-terminated fluorinated polysiloxane is as follows: octamethylcyclotetrasiloxane, trifluoropropylcyclotetrasiloxane, and sulfuric acid are mixed and stirred, the reaction system is heated to 85-95℃, and the reaction is maintained at this temperature for 3.5-4.5 h. Then, 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane is added to the reaction system, and the reaction is maintained at this temperature for 2-3 h. After post-treatment, the hydroxyl-terminated fluorinated polysiloxane is obtained.

[0010] The synthesis reaction formula for hydroxyl-terminated fluorinated polysiloxanes is as follows: Further, the ratio of octamethylcyclotetrasiloxane, trifluoropropylcyclotetrasiloxane, sulfuric acid, and 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane is 1g:1g:0.2mL:0.3-0.4g, and the mass fraction of the sulfuric acid is 80-90%. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, adding toluene and purified water to the reaction system, stirring and dispersing for 20-30 minutes, washing the organic phase with purified water until neutral, drying it under vacuum, transferring the organic phase to a rotary evaporator with a water bath temperature of 80-90℃, removing low-boiling substances under reduced pressure, and obtaining hydroxyl-terminated fluorinated polysiloxane.

[0011] Furthermore, the surface-modified far-infrared functional composite powder is obtained by the following steps: A1. Mix far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate evenly to obtain a far-infrared functional composite powder solution. A2. Under an inert gas atmosphere, hydroxyl-terminated fluorinated polysiloxane and N-methylpyrrolidone are mixed and stirred. The reaction system is heated to 50-60℃. Propyltriethoxysilane isocyanate is added to the reaction system, and the reaction is maintained at this temperature for 40-60 min. Far-infrared functional composite powder solution is added to the reaction system, and ultrasonic dispersion is carried out for 30-50 min. Sodium hydroxide solution is added to the reaction system, and the coating reaction is carried out for 60-80 min. After post-treatment, surface-modified far-infrared functional composite powder is obtained.

[0012] Further, in step A1, the ratio of the far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate is 5g:30mL:0.6-0.8g:0.1g; in step A2, the ratio of the hydroxyl-terminated fluorinated polysiloxane, N-methylpyrrolidone, far-infrared functional composite powder solution, and sodium hydroxide solution is 3g:50mL:50-60mL, and the amount of propyltriethoxysilane isocyanate is 0.55-0.6 times the molar amount of the hydroxyl-terminated fluorinated polysiloxane. The post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at a temperature of 60-70℃ and dried to constant weight to obtain surface-modified far-infrared functional composite powder.

[0013] Furthermore, the preparation method of polyurethane prepolymer is as follows: under the protection of an inert gas atmosphere, polytetrahydrofuran ether diol and tetrahydrofuran are mixed and stirred, the reaction system is heated to 50-60℃, isoflurane diisocyanate is added to the reaction system, the reaction is kept at the temperature for 50-60 min, and then post-processed to obtain polyurethane prepolymer.

[0014] The synthesis reaction formula for polyurethane prepolymer is: Further, the ratio of polytetrahydrofuran ether diol to tetrahydrofuran is 1g:7mL, the molar amount of isoflurane diisocyanate is 0.55-0.6 times the molar amount of polytetrahydrofuran ether diol, and the post-treatment includes: after the reaction is completed, the reaction system is subjected to negative pressure, and low-boiling substances are removed by vacuum evaporation to obtain polyurethane prepolymer.

[0015] The present invention also proposes a method for preparing a far-infrared functional composite material, comprising the following steps: adding surface-modified far-infrared functional composite powder, composite polymer matrix and auxiliary additives into a twin-screw extruder, melting and blending at 240-280℃ for 3-5 minutes, and then extruding the mixture into a melt spinning machine at 260-280℃ for melt spinning, setting the spinning speed to 800-1000 m / min to obtain nascent fibers, hot stretching the nascent fibers at 150-200℃, setting the stretching ratio to 2.5-3.5 times to obtain coarse fibers, heat-setting the coarse fibers at 180-220℃ for 5-10 minutes, controlling the warp relaxation rate of the fabric to 10-20% during the heat-setting process, to obtain the far-infrared functional composite material.

[0016] This invention also proposes an application of a far-infrared functional composite material, which is applied to textiles.

[0017] The present invention has the following beneficial effects: 1. This invention involves the synergistic design of the component blending, particle size distribution, and composite polymer matrix structure of far-infrared functional powders, taking into account functionality, mechanical properties, and thermal dimensional stability. The blending of tourmaline and zircon not only ensures the source of far-infrared functionality but also enhances the stability of the inorganic filler system by leveraging the thermal stability and skeletal support of zircon. Simultaneously, the blending of large and small particles creates a bimodal particle size distribution, with small particles filling the gaps between large particles, increasing packing density and interfacial contact area, thereby improving the uniformity of powder dispersion and load transfer efficiency within the matrix. The composite polymer matrix is ​​composed of flexible polyurethane segments and polyamic acid, subsequently imidized into a rigid structure and densified with epoxy. The flexible segments buffer stress and improve toughness, the rigid aromatic structure enhances heat resistance and dimensional stability, and the epoxy structure strengthens the system's density and interfacial locking ability. This results in a more rational spatial distribution of the far-infrared functional composite powder, more stable interfacial interactions, and more adequate matrix support, maintaining high tensile strength and superior dimensional stability while improving the material's far-infrared emissivity.

[0018] 2. This invention also prepares hydroxyl-terminated fluorinated polysiloxanes using octamethylcyclotetrasiloxane and trifluoropropylcyclotetrasiloxane, and then grafts and fixes them onto the surface of tourmaline / zircon composite powder using propyltriethoxysilane. This forms a coating layer with both organic affinity and low surface energy characteristics on the outer layer of the inorganic particles of the far-infrared functional composite powder. On the one hand, this coating layer can form a stable bond with the surface of inorganic particles through silane hydrolysis and condensation. On the other hand, it can improve the wettability and dispersibility of particles in the composite polymer matrix by means of fluorinated polysiloxane segments, reduce particle agglomeration and local defects, and keep the functional powder in a uniform, stable and non-leaking distribution state inside the material. This achieves the technical effect of high far-infrared emissivity and maintaining a high level of far-infrared emissivity even after water washing.

[0019] 3. This invention also enables the surface-modified far-infrared functional powder to be more uniformly dispersed in the composite polymer matrix during the twin-screw melt blending process, avoiding severe agglomeration of unmodified particles under high-temperature shear conditions; during melt spinning, the suitable rheological properties and interfacial compatibility of the composite matrix are conducive to continuous fiber forming; after hot stretching, the polymer chain segments are further oriented along the fiber axis, improving the efficiency of load transfer along the axis, thereby enhancing the breaking strength; after heat setting, the residual stress inside the fiber is released, and the formed ordered structure is effectively fixed, reducing the dimensional changes caused by heat treatment and repeated washing, so that the far-infrared functional composite material simultaneously possesses high far-infrared emissivity, high breaking strength, good thermal dimensional stability, and excellent washability. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In this application, the polytetrahydrofuran ether diol is designated as PTMEG1000; In this application, the epoxy resin is a bisphenol A type epoxy resin, model E-44.

[0022] Example 1 This embodiment provides a method for preparing surface-modified far-infrared functional composite powder, including the following steps: Step 1: Preparation of hydroxyl-terminated fluorinated polysiloxane Weigh out 100g of octamethylcyclotetrasiloxane, 100g of trifluoropropylcyclotetrasiloxane, and 20mL of 80wt% sulfuric acid and add them to a reaction flask. Stir the mixture and heat the flask to 85℃. Maintain the temperature for 3.5h. Add 30g of 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane to the reaction flask and maintain the temperature for 2h. Cool the reaction flask to room temperature and add 500mL of toluene and 500mL of purified water. Stir and disperse for 20min. Wash the organic phase with purified water until neutral and then dry it under vacuum. Transfer the organic phase to a rotary evaporator with a water bath temperature of 80℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances under reduced pressure to obtain hydroxyl-terminated fluorinated polysiloxane.

[0023] In the reaction, octamethylcyclotetrasiloxane and trifluoropropylcyclotetrasiloxane undergo a ring-opening equilibrium polymerization reaction under sulfuric acid catalysis, causing the rings to open and rearrange, forming a linear polysiloxane structure with silicon-oxygen bonds as the main chain. 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane is used as a capping agent to form hydroxyl groups at the ends of the linear polysiloxane chains, thus preparing hydroxyl-capped fluorinated polysiloxanes.

[0024] Linear polysiloxane segments have good flexibility, high heat resistance and low surface tension, which are beneficial for subsequent use as interfacial transition segments to improve the compatibility between powder and matrix; trifluoropropyl side groups further reduce the polymer surface energy, improve hydrophobicity, stain resistance and interfacial migration ability, making it easier for the coating layer formed on the surface of inorganic powder to be compatible with the organic polymer matrix.

[0025] Step 2: Preparation of far-infrared functional composite powder Tourmaline and zircon were mixed evenly at a weight ratio of 3:1 and pulverized to obtain mixed powder one with a particle size distribution D50 of 2-5μm and mixed powder two with a particle size distribution D50 of 0.5-1μm. Mixed powder one and mixed powder two were mixed evenly at a weight ratio of 6:4 to obtain far-infrared functional composite powder.

[0026] The particle size distribution of far-infrared functional composite powder is optimized. Large-diameter particles form the functional filler skeleton, providing the main far-infrared functional phase and a certain skeleton support. Small-diameter particles fill the gaps between large particles, increasing the packing density of the powder, reducing pore defects, increasing the specific surface area and the contact interface with the matrix, thereby improving the spatial distribution uniformity of the powder in the matrix. The bimodal particle size compound not only helps to improve the effective distribution of the far-infrared functional phase, but also improves the load transfer efficiency between the inorganic / organic interface and reduces local stress concentration.

[0027] Step 3: Preparation of surface-modified far-infrared functional composite powder The far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate were mixed at a ratio of 5g:30mL:0.6g:0.1g and ultrasonically dispersed for 30min to obtain a far-infrared functional composite powder solution. Weigh out 90g of hydroxyl-terminated fluorinated polysiloxane and 1500mL of N-methylpyrrolidone and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 50℃. Calculate the amount of propyltriethoxysilane to be added based on 0.55 times the molar amount of hydroxyl-terminated fluorinated polysiloxane and add it to the reaction flask. Keep the mixture warm for 40min. Add 1500mL of far-infrared functional composite powder solution to the reaction flask and ultrasonically disperse for 30min. Fix the reaction flask on an iron stand and keep the mixture warm for 60min. Cool the reaction flask to room temperature and filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 60℃ and dry it to constant weight to obtain surface-modified far-infrared functional composite powder.

[0028] In the reaction, the hydroxyl groups on the terminal hydroxyl-containing fluorinated polysiloxane molecular chain react and bond with the isocyanate on the isocyanate propyltriethoxysilane molecule, forming a triethoxysilane modification on the linear polysiloxane chain. Then, under alkaline conditions, the triethoxysilane hydrolyzes to form silanol, which chemically bonds with the outside of the far-infrared functional composite powder particles, forming a fluorinated polysiloxane coating on the outside of the particles. This reduces the polarity and surface energy of the inorganic particle surface, making the particles easier to wet with the composite polymer matrix, thereby improving dispersibility. The coating layer forms a flexible interface transition layer between the inorganic particles and the organic matrix, reducing interface mismatch and local stress concentration, which is beneficial to improving fracture strength. Moreover, it transforms the bonding between the functional powder and the matrix from simple physical intercalation to a more stable interface-locked state, thereby reducing powder migration and shedding during the washing process, which is beneficial to maintaining far-infrared emissivity and size retention.

[0029] Example 2 This embodiment provides a method for preparing surface-modified far-infrared functional composite powder, including the following steps: Step 1: Preparation of hydroxyl-terminated fluorinated polysiloxane Weigh out 100g of octamethylcyclotetrasiloxane, 100g of trifluoropropylcyclotetrasiloxane, and 20mL of 85wt% sulfuric acid and add them to a reaction flask. Stir the mixture and heat it to 90℃. Keep the mixture at this temperature for 4h. Add 35g of 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane to the reaction flask and keep the mixture at this temperature for 2.5h. Cool the reaction flask to room temperature and add 500mL of toluene and 500mL of purified water. Stir and disperse the mixture for 25min. Wash the organic phase with purified water until neutral and then dry it under vacuum. Transfer the organic phase to a rotary evaporator with a water bath temperature of 85℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances under reduced pressure to obtain hydroxyl-terminated fluorinated polysiloxane.

[0030] Step 2: Preparation of far-infrared functional composite powder Tourmaline and zircon were mixed evenly at a weight ratio of 4:1 and pulverized to obtain mixed powder one with a particle size distribution D50 of 2-5μm and mixed powder two with a particle size distribution D50 of 0.5-1μm. Mixed powder one and mixed powder two were mixed evenly at a weight ratio of 6.5:3.5 to obtain far-infrared functional composite powder.

[0031] Step 3: Preparation of surface-modified far-infrared functional composite powder The far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate were mixed at a ratio of 5g:30mL:0.7g:0.1g and ultrasonically dispersed for 40min to obtain a far-infrared functional composite powder solution. Weigh out 90g of hydroxyl-terminated fluorinated polysiloxane and 1500mL of N-methylpyrrolidone and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 55℃. Calculate the amount of propyltriethoxysilane to be added based on 0.57 times the molar amount of hydroxyl-terminated fluorinated polysiloxane and add it to the reaction flask. Keep the mixture warm for 50min. Add 1650mL of far-infrared functional composite powder solution to the reaction flask and ultrasonically disperse for 40min. Fix the reaction flask on an iron stand and keep the mixture warm for 70min. Cool the reaction flask to room temperature and filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 65℃ and dry it to constant weight to obtain surface-modified far-infrared functional composite powder.

[0032] Example 3 This embodiment provides a method for preparing surface-modified far-infrared functional composite powder, including the following steps: Step 1: Preparation of hydroxyl-terminated fluorinated polysiloxane Weigh out 100g of octamethylcyclotetrasiloxane, 100g of trifluoropropylcyclotetrasiloxane, and 20mL of 90wt% sulfuric acid and add them to a reaction flask. Stir the mixture and heat the flask to 95℃. Maintain the temperature for 4.5h. Add 40g of 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane to the reaction flask and maintain the temperature for 3h. Cool the reaction flask to room temperature and add 500mL of toluene and 500mL of purified water. Stir and disperse for 30min. Wash the organic phase with purified water until neutral and then dry it under vacuum. Transfer the organic phase to a rotary evaporator with a water bath temperature of 90℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances under reduced pressure to obtain hydroxyl-terminated fluorinated polysiloxane.

[0033] Step 2: Preparation of far-infrared functional composite powder Tourmaline and zircon were mixed evenly at a weight ratio of 5:1 and pulverized to obtain mixed powder one with a particle size distribution D50 of 2-5μm and mixed powder two with a particle size distribution D50 of 0.5-1μm. Mixed powder one and mixed powder two were mixed evenly at a weight ratio of 7:3 to obtain far-infrared functional composite powder.

[0034] Step 3: Preparation of surface-modified far-infrared functional composite powder The far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate were mixed at a ratio of 5g:30mL:0.8g:0.1g and ultrasonically dispersed for 50min to obtain a far-infrared functional composite powder solution. Weigh out 90g of hydroxyl-terminated fluorinated polysiloxane and 1500mL of N-methylpyrrolidone and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 60℃. Calculate the amount of propyltriethoxysilane to be added based on 0.6 times the molar amount of hydroxyl-terminated fluorinated polysiloxane and add it to the reaction flask. Keep the mixture warm for 60min. Add 1800mL of far-infrared functional composite powder solution to the reaction flask and ultrasonically disperse for 50min. Fix the reaction flask on an iron stand and keep the mixture warm for 80min. Cool the reaction flask to room temperature and filter the mixture. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain surface-modified far-infrared functional composite powder.

[0035] Example 4 This embodiment provides a method for preparing a composite polymer matrix, including the following steps: Step I: Preparation of polyurethane prepolymer Weigh 100g of polytetrahydrofuran ether diol and 700mL of tetrahydrofuran into an argon-protected reaction flask and stir. Heat the reaction flask to 50℃. Calculate the amount of isoflurane diisocyanate to be added based on 0.55 times the molar amount of polytetrahydrofuran ether diol and add it to the reaction flask. Keep the reaction at this temperature for 50min. Then, evacuate the reaction flask to -0.1MPa and remove low-boiling-point substances by vacuum distillation to obtain the polyurethane prepolymer.

[0036] In the reaction, polytetrahydrofuran ether diol undergoes an addition reaction with isophorone diisocyanate to form urethane bonds, thus forming a polyurethane prepolymer. Polytetrahydrofuran ether diol is a flexible polyether diol with compliant chain segments, which gives the system good toughness and ductility.

[0037] Step II: Preparation of composite polymer matrix The polyurethane prepolymer and N,N-dimethylacetamide were mixed at a ratio of 1g:4mL and stirred until the system was dissolved to obtain a polyurethane prepolymer solution. Weigh out 218.1 g of pyromellitic dianhydride, 240.3 g of 4,4'-diaminodiphenyl ether, and 2403 mL of N,N-dimethylacetamide and add them to an argon-protected reaction flask. Stir until the system dissolves and react at room temperature for 22 h. Add 2403 mL of polyurethane prepolymer solution to the reaction flask, heat the flask to 60 °C, and maintain the temperature for 40 min. Add 72.1 g of epoxy resin to the reaction flask and stir for 30 min. Cool the reaction flask to room temperature and add 4800 mL of 1 wt% sodium dodecyl sulfate solution. Stir and disperse for 30 min, filter, wash the filter cake three times with purified water, and dry it under vacuum. Transfer the filter cake to a drying oven at 80 °C and dry it under vacuum to constant weight to obtain the composite polymer matrix.

[0038] In the reaction, pyromellitic dianhydride and 4,4'-diaminodiphenyl ether first undergo polycondensation in N,N-dimethylacetamide to form a polyamic acid precursor. Subsequently, a polyurethane prepolymer is added, allowing the rigid polyamic acid precursor segments and the flexible polyurethane segments to coexist in the same system. The amino groups on the polyamic acid precursor molecules and the isocyanate groups on the polyurethane prepolymer molecules undergo condensation to form a composite structure that combines rigidity and flexibility. The polyamic acid and the subsequent imidized aromatic structure further improve the material's heat resistance, rigidity, and thermal dimensional stability. The polyurethane segments mainly provide flexibility and stress buffering capacity. After the addition of epoxy resin, the epoxy groups can react with the hydroxyl, carboxyl, or residual active groups in the system, thereby improving the system's density and interface locking ability.

[0039] Example 5 This embodiment provides a method for preparing a composite polymer matrix, including the following steps: Step I: Preparation of polyurethane prepolymer Weigh 100g of polytetrahydrofuran ether diol and 700mL of tetrahydrofuran into an argon-protected reaction flask and stir. Heat the reaction flask to 55℃. Calculate the amount of isoflurane diisocyanate to be added based on 0.57 times the molar amount of polytetrahydrofuran ether diol and add it to the reaction flask. Keep the reaction at this temperature for 55 minutes. Then, evacuate the reaction flask to -0.1MPa and remove low-boiling-point substances by vacuum distillation to obtain the polyurethane prepolymer.

[0040] Step II: Preparation of composite polymer matrix The polyurethane prepolymer and N,N-dimethylacetamide were mixed at a ratio of 1g:4.5mL and stirred until the system was dissolved to obtain a polyurethane prepolymer solution. Weigh out 218.1 g of pyromellitic dianhydride, 240.3 g of 4,4'-diaminodiphenyl ether, and 2403 mL of N,N-dimethylacetamide and add them to an argon-protected reaction flask. Stir until the system dissolves and react at room temperature for 23 h. Add 2403 mL of polyurethane prepolymer solution to the reaction flask, heat the flask to 65 °C, and maintain the temperature for 45 min. Add 96.1 g of epoxy resin to the reaction flask and stir for 40 min. Cool the reaction flask to room temperature and add 4800 mL of 1 wt% sodium dodecyl sulfate solution. Stir and disperse for 40 min, filter, wash the filter cake three times with purified water, and dry it under vacuum. Transfer the filter cake to a drying oven at 85 °C and dry it under vacuum to constant weight to obtain the composite polymer matrix.

[0041] Example 6 This embodiment provides a method for preparing a composite polymer matrix, including the following steps: Step I: Preparation of polyurethane prepolymer Weigh 100g of polytetrahydrofuran ether diol and 700mL of tetrahydrofuran into an argon-protected reaction flask and stir. Heat the reaction flask to 60℃. Calculate the amount of isoflurane diisocyanate to be added based on 0.6 times the molar amount of polytetrahydrofuran ether diol and add it to the reaction flask. Keep the reaction at this temperature for 60min. Then, evacuate the reaction flask to -0.1MPa and remove low-boiling-point substances by vacuum distillation to obtain the polyurethane prepolymer.

[0042] Step II: Preparation of composite polymer matrix The polyurethane prepolymer and N,N-dimethylacetamide were mixed at a ratio of 1g:5mL and stirred until the system was dissolved to obtain a polyurethane prepolymer solution. Weigh out 218.1 g of pyromellitic dianhydride, 240.3 g of 4,4'-diaminodiphenyl ether, and 2403 mL of N,N-dimethylacetamide and add them to an argon-protected reaction flask. Stir until the system dissolves and react at room temperature for 24 h. Add 2403 mL of polyurethane prepolymer solution to the reaction flask, heat the flask to 70 °C, and maintain the temperature for 50 min. Add 120.1 g of epoxy resin to the reaction flask and stir for 50 min. Cool the reaction flask to room temperature and add 4800 mL of 1 wt% sodium dodecyl sulfate solution. Stir and disperse for 50 min, filter, wash the filter cake three times with purified water, and dry it under vacuum. Transfer the filter cake to a drying oven at 90 °C and dry it under vacuum to constant weight to obtain the composite polymer matrix.

[0043] Example 7 This embodiment provides a method for preparing a far-infrared functional composite material, including the following steps: Step S1: Material preparation Calcium stearate, ethylene bis-stearamide, antioxidant 1010, antistatic agent SN and diisobutyl phthalate were mixed evenly in a weight ratio of 3:1:1:1:5 to obtain auxiliary additives. Weigh out the following by weight: 25 parts of the surface-modified far-infrared functional composite powder prepared in Example 1, 75 parts of the composite polymer matrix prepared in Example 4, and 2 parts of auxiliary additives, and mix them evenly to obtain a mixture.

[0044] Step S2: Preparation of nascent fibers The mixture was added to a twin-screw extruder, and the temperatures of the twin-screw extruder were set to 260℃ in zone I, 265℃ in zone II, 270℃ in zone III, 270℃ in zone IV, 270℃ in zone V, 275℃ in zone VI, and 280℃ in the die zone. After melt blending for 3 minutes, the mixture was extruded into a melt spinning machine at a temperature of 260℃ for melt spinning. The spinning speed was set to 800 m / min to obtain nascent fibers.

[0045] Step S3: Prepare far-infrared functional composite material. The nascent fiber is hot-stretched at 150°C with a stretching ratio of 2.5 times to obtain a coarse fiber. The coarse fiber is then heat-set at 180°C for 5 minutes. During the heat-setting process, the warp relaxation rate of the fabric is controlled at 10% to obtain the far-infrared functional composite material.

[0046] Example 8 This embodiment provides a method for preparing a far-infrared functional composite material, including the following steps: Step S1: Material preparation Zinc stearate, ethylene bis-stearamide, antioxidant 1010, antistatic agent SN and butyl phthalate were mixed evenly in a weight ratio of 3:1:1:1:5 to obtain auxiliary additives. Weigh out the following by weight: 30 parts of the surface-modified far-infrared functional composite powder prepared in Example 2, 80 parts of the composite polymer matrix prepared in Example 5, and 2.5 parts of auxiliary additives, and mix them evenly to obtain a mixture.

[0047] Step S2: Preparation of nascent fibers The mixture was added to a twin-screw extruder, and the temperatures of the twin-screw extruder were set to 260℃ in zone I, 265℃ in zone II, 270℃ in zone III, 270℃ in zone IV, 270℃ in zone V, 275℃ in zone VI, and 280℃ in the die zone. After melt blending for 4 minutes, the mixture was extruded into a melt spinning machine at a temperature of 270℃ for melt spinning. The spinning speed was set to 900 m / min to obtain nascent fibers.

[0048] Step S3: Prepare far-infrared functional composite material. The nascent fibers are hot-stretched at 175°C with a stretching ratio of 3.0 times to obtain coarse fiber. The coarse fiber is then heat-set at 200°C for 7.5 minutes. During the heat-setting process, the warp relaxation rate of the fabric is controlled at 15% to obtain the far-infrared functional composite material.

[0049] Example 9 This embodiment provides a method for preparing a far-infrared functional composite material, including the following steps: Step S1: Material preparation Sodium stearate, ethylene bis-stearamide, antioxidant 1010, antistatic agent SN and dioctyl phthalate were mixed evenly in a weight ratio of 3:1:1:1:5 to obtain auxiliary additives. Weigh out the following by weight: 35 parts of the surface-modified far-infrared functional composite powder prepared in Example 3, 85 parts of the composite polymer matrix prepared in Example 6, and 3 parts of auxiliary additives, and mix them evenly to obtain a mixture.

[0050] Step S2: Preparation of nascent fibers The mixture was added to a twin-screw extruder, and the temperatures of the twin-screw extruder were set to 260℃ in zone I, 265℃ in zone II, 270℃ in zone III, 270℃ in zone IV, 270℃ in zone V, 275℃ in zone VI, and 280℃ in the die zone. After melt blending for 5 minutes, the mixture was extruded into a melt spinning machine at a temperature of 280℃ for melt spinning. The spinning speed was set to 1000 m / min to obtain nascent fibers.

[0051] Step S3: Prepare far-infrared functional composite material. The nascent fibers are hot-stretched at 200℃ with a stretching ratio of 3.5 times to obtain coarse fiber. The coarse fiber is then heat-set at 220℃ for 10 minutes. During the heat-setting process, the warp relaxation rate of the fabric is controlled at 20% to obtain the far-infrared functional composite material.

[0052] Comparative Example 1 The difference between this comparative example and Example 9 is that the surface-modified far-infrared functional composite powder used is replaced by an equal amount of the far-infrared functional composite powder in step 2.

[0053] Comparative Example 2 The difference between this comparative example and Example 9 is that, in the preparation of the surface-modified far-infrared functional composite powder, the mixed powder II was not added in step 2.

[0054] Comparative Example 3 The difference between this comparative example and Example 9 is that, in the preparation of the surface-modified far-infrared functional composite powder, the hydroxyl-terminated fluorinated polysiloxane in step 2 is replaced by an equal amount of polytetrahydrofuran ether diol.

[0055] Comparative Example 4 The difference between this comparative example and Example 9 is that, in the preparation of the composite polymer matrix, the mixture of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in step II is replaced by polytetrahydrofuran ether diol in equal amounts.

[0056] Performance testing: The far-infrared emissivity of the far-infrared functional composite materials prepared in Examples 7-9 and Comparative Examples 1-4 was determined in accordance with the standard GB / T 30127-2013 "Detection and Evaluation of Far-Infrared Properties of Textiles". Referring to standard GB / T 3923.1-2013 "Textiles - Tensile Properties of Fabrics - Part 1: Determination of Breaking Strength and Elongation at Break (Strip Method)", the tensile rate was set to 100 mm / min, and the elongation at break and breaking strength of the far-infrared functional composite materials prepared in Examples 7-9 and Comparative Examples 1-4 were measured. The far-infrared functional composite materials prepared in Examples 7-9 and Comparative Examples 1-4 were placed in an oven at 150°C and kept at that temperature for 20 minutes, then processed according to the formula. The dimensional stability of the test sample is determined, where L0 is the length of the far-infrared functional composite material before heat treatment, and L1 is the length of the far-infrared functional composite material after heat treatment. After washing the far-infrared functional composite materials prepared in Examples 7-9 and Comparative Examples 1-4 100 times, the far-infrared emissivity and dimensional retention of the samples were measured. The specific test data are shown in Table 1 below.

[0057] Table 1 - Performance Test Data of Samples Data Analysis: The far-infrared functional composite material prepared by this invention has a far-infrared emissivity of 0.89-0.93, an elongation at break of 52.7-56.6%, a tensile strength of 650-693 cN, and a dimensional stability of 98.2-98.8%. After 100 water washes, the far-infrared emissivity of the sample reaches 0.87-0.90, and the dimensional retention rate reaches 97.3-98.2%. All performance test data are superior to those of the comparative example. This indicates that the present invention optimizes the particle size distribution of the far-infrared functional powder to form a bimodal particle size distribution, chemically modifies the powder surface, and then uses a rigid-flexible composite polymer matrix composed of polyamic acid precursor, polyurethane prepolymer, and epoxy resin to synergistically work with the surface-modified far-infrared functional composite powder. This not only effectively improves the far-infrared emission performance and mechanical properties of the far-infrared functional composite material, but also improves the thermal dimensional stability and washability of the material.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A far infrared functional composite material, characterized by comprising: a far infrared material; and a resin material. It comprises the following components by weight: 25-35 parts of surface-modified far-infrared functional composite powder and 75-85 parts of composite polymer matrix; The surface-modified far-infrared functional composite powder is obtained by surface modification of far-infrared functional composite powder with hydroxyl-terminated fluorinated polysiloxane. The method for preparing the composite polymer matrix is ​​as follows: Under an inert gas atmosphere, pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, and N,N-dimethylacetamide are mixed and stirred until dissolved. The mixture is stirred at room temperature for 22-24 hours. A polyurethane prepolymer solution is added to the reaction system, and the temperature is raised to 60-70°C. The reaction is maintained at this temperature for 40-50 minutes. Epoxy resin is added to the reaction system, and the mixture is stirred for 30-50 minutes. After post-treatment, the composite polymer matrix is ​​obtained.

2. The far infrared functional composite material according to claim 1, characterized in that, The ratio of 4,4'-diaminodiphenyl ether, N,N-dimethylacetamide, polyurethane prepolymer solution, and epoxy resin is 1g:10mL:10mL:0.3-0.5g, and the ratio of pyromellitic dianhydride to 4,4'-diaminodiphenyl ether is 1mol: 1.2 mol, wherein the polyurethane prepolymer solution is composed of polyurethane prepolymer and N,N-dimethylacetamide at a ratio of 1 g: 4-5 mL.

3. The far infrared functional composite material according to claim 1, characterized in that, The far-infrared functional composite powder is composed of tourmaline and zircon in a weight ratio of (3-5):1; the far-infrared functional composite powder has a bimodal particle size distribution, with the first particle size distribution having a D50 of 2-5 μm and the second particle size distribution having a D50 of 0.5-1 μm, and the weight ratio of the first particle size distribution to the second particle size distribution being (6-7):(4-3).

4. The far infrared functional composite material according to claim 1, characterized in that, The preparation method of the hydroxyl-terminated fluorinated polysiloxane is as follows: octamethylcyclotetrasiloxane, trifluoropropylcyclotetrasiloxane, and sulfuric acid are mixed and stirred. The reaction system is heated to 85-95℃ and kept at this temperature for 3.5-4.5 hours. Then, 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane is added to the reaction system and kept at this temperature for 2-3 hours. After post-treatment, the hydroxyl-terminated fluorinated polysiloxane is obtained.

5. The far infrared functional composite material according to claim 4, wherein The ratio of octamethylcyclotetrasiloxane, trifluoropropylcyclotetrasiloxane, sulfuric acid, and 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane is 1g:1g:0.2mL:0.3-0.4g, and the sulfuric acid has a mass fraction of 80-90%.

6. The far-infrared functional composite material according to claim 1, characterized in that, The surface-modified far-infrared functional composite powder is obtained by the following steps: A1. Mix far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate evenly to obtain a far-infrared functional composite powder solution. A2. Under an inert gas atmosphere, hydroxyl-terminated fluorinated polysiloxane and N-methylpyrrolidone are mixed and stirred. The reaction system is heated to 50-60℃. Propyltriethoxysilane isocyanate is added to the reaction system, and the reaction is maintained at this temperature for 40-60 min. Far-infrared functional composite powder solution is added to the reaction system, and ultrasonic dispersion is carried out for 30-50 min. Sodium hydroxide solution is added to the reaction system, and the coating reaction is carried out for 60-80 min. After post-treatment, surface-modified far-infrared functional composite powder is obtained.

7. The far-infrared functional composite material according to claim 6, characterized in that, In step A1, the ratio of the far-infrared functional composite powder, deionized water, sodium hydroxide, and sodium dodecyl sulfate is 5g:30mL:0.6-0.8g:0.1g; in step A2, the ratio of the hydroxyl-terminated fluorinated polysiloxane, N-methylpyrrolidone, far-infrared functional composite powder solution, and sodium hydroxide solution is 3g:50mL:50-60mL, and the amount of propyltriethoxysilane is 0.55-0.6 times the molar amount of the hydroxyl-terminated fluorinated polysiloxane.

8. The far-infrared functional composite material according to claim 1, characterized in that, The preparation method of polyurethane prepolymer is as follows: under the protection of an inert gas atmosphere, polytetrahydrofuran ether diol and tetrahydrofuran are mixed and stirred, the reaction system is heated to 50-60℃, isoflurane diisocyanate is added to the reaction system, the reaction is kept at the temperature for 50-60 min, and then post-treatment is performed to obtain polyurethane prepolymer.

9. A method for preparing a far-infrared functional composite material according to any one of claims 1-8, characterized in that, The process includes the following steps: adding surface-modified far-infrared functional composite powder, composite polymer matrix, and auxiliary additives into a twin-screw extruder, melting and blending at 240-280℃ for 3-5 minutes, and then extruding the mixture into a melt spinning machine at 260-280℃ for melt spinning at a spinning speed of 800-1000 m / min to obtain nascent fibers. The nascent fibers are then hot-stretched at 150-200℃ with a stretching ratio of 2.5-3.5 times to obtain coarse fibers. The coarse fibers are then heat-set at 180-220℃ for 5-10 minutes, controlling the warp relaxation rate of the fabric to 10-20% during the heat-setting process to obtain a far-infrared functional composite material.

10. An application of a far-infrared functional composite material, characterized in that, The far-infrared functional composite material as described in any one of claims 1-8 is applied to textiles.

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