Preparation method of environment-friendly anti-ultraviolet composite fabric

Abstract

The invention relates to the technical field of fabrics, in particular to a preparation method of an environment-friendly anti-ultraviolet composite fabric. According to the method, cotton, polylactic acid and bamboo fibers are finely proportioned to prepare an outer-layer fabric, zinc oxide nanoparticles and a polylactic acid solution are subjected to electrostatic spinning to form a functional interlayer, and the cotton and the polylactic acid fibers are subjected to alkali treatment and anti-ultraviolet finishing to form an inner-layer fabric. The preparation method comprises the following steps: preparing an outer layer, a functional interlayer and an inner layer, mixing acrylic acid modified waterborne polyurethane with berberine extract powder, adding nano titanium dioxide to prepare a coating adhesive, sequentially overlapping and fixing the outer layer, the functional interlayer and the inner layer through ultrasonic spot welding, applying the coating adhesive, curing, washing with water and drying to obtain a finished product. According to the designed composite fabric, efficient ultraviolet resistance is achieved through the synergistic effect of the functional interlayer and the surface coating, the mechanical property and environmental friendliness of the fabric are improved, the coating glue only forms the functional layer on the outer layer, and the situation that the air permeability is reduced due to interlayer gluing is avoided.

Description

Technical Field

[0001] This invention relates to the field of fabric technology, specifically to a method for preparing an environmentally friendly UV-resistant composite fabric. Background Technology

[0002] Currently, with the intensification of global climate change and the increasing health awareness of consumers, UV-resistant functional fabrics have become a key demand in the fields of outdoor protection, daily clothing, and medical supplies. However, existing UV-resistant fabric technologies still face multiple contradictions, making it difficult to balance protective performance, wearing comfort, and environmental friendliness. Although traditional coating processes can achieve UV protection through UV absorbers or reflectors, the coatings easily clog fabric pores, leading to a significant decrease in breathability, resulting in a strong feeling of stuffiness when wearing in summer. Furthermore, the functional layer is prone to peeling off after repeated washing, indicating insufficient durability. Some products improve environmental friendliness by increasing fabric density or using natural fibers, but the UPF value is limited (e.g., cotton fiber UPF is usually ≤30), limiting the protective ability. At the material application level, although biodegradable materials such as polylactic acid fibers are in line with the green trend, their poor dyeing performance and low color fastness limit their market promotion. While inorganic nanoparticles such as zinc oxide have highly efficient UV shielding capabilities, their strong surface polarity and tendency to agglomerate lead to a high breakage rate during spinning and uneven distribution of functional particles, significantly affecting the mechanical properties of the fabric. Furthermore, existing coating adhesive technologies mostly rely on solvent-based systems, which raise VOC emissions issues. Additionally, the coating's adhesion to the substrate is weak, leading to problems such as adhesive seepage and peeling, further exacerbating the conflict between functionality and comfort. These technological bottlenecks necessitate a composite fabric solution that can maintain high UV resistance while also offering breathability, environmental friendliness, and durability. Summary of the Invention

[0003] Based on the problems existing in the above-mentioned background technology, the present invention proposes a method for preparing an environmentally friendly UV-resistant composite fabric, the steps of which are as follows.

[0004] Step 1: Outer fabric preparation. Cotton fiber, polylactic acid fiber and bamboo fiber are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The fabric is woven on an air-jet loom using a twill weave.

[0005] Step 2: Preparation of functional sandwich layer: Zinc oxide nanoparticles and polylactic acid solution are mixed at a mass ratio of 3:100, and nanofiber membranes are prepared by electrospinning device;

[0006] Step 3: Inner layer fabric preparation: Cotton fibers and polylactic acid fibers are treated with alkali and then immersed in an anti-UV finishing solution. Subsequently, ultrasonic treatment is used to promote the penetration of functional particles. After drying, 18tex yarn is spun and woven on a rapier loom using a plain weave structure.

[0007] Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane and berberine extract powder are mixed at a mass ratio of 92:8. Then, nano titanium dioxide is added to the mixture for high-speed dispersion. Aziridine blocked polyisocyanate is added and stirring is continued for 15 minutes.

[0008] Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are stacked in sequence, and the four sides are fixed by ultrasonic spot welding. The coating adhesive is applied by a scraper coating machine, cured at 80°C for 3 minutes, and after cooling, washed and dried to obtain the finished product.

[0009] Preferably, in step 1, the mass ratio of cotton fiber, polylactic acid fiber and bamboo fiber in the outer fabric is 25:60:15, the twill weave is 3 / 1 warp right twill, and the warp and weft density of the woven outer fabric is 200 threads / 10cm × 180 threads / 10cm.

[0010] Preferably, in step 2, the zinc oxide nanoparticles have a particle size of 30-50 nm, the polylactic acid concentration is 8 wt%, the electrospinning voltage is 15 kV, the electrospinning receiving distance is 15-20 cm, the nanofiber membrane has a fiber diameter of 150-250 nm, and the nanofiber membrane thickness is 0.05 mm. During the electrospinning process, the ambient humidity is controlled at 35% ± 5%, and the temperature is 25℃ ± 2℃ to optimize the fiber morphology.

[0011] Preferably, in step 3, the mass ratio of cotton fiber to polylactic acid fiber is 25:75, the ultrasonic treatment parameters are: ultrasonic power set to 28kHz, ultrasonic time 5min, the drying temperature is 65℃±5℃, the drying time is 12-15min, and the warp and weft density of the woven inner fabric is 180 threads / 10cm×160 threads / 10cm.

[0012] Preferably, in step 3, the alkali treatment step involves immersing cotton fibers and polylactic acid fibers in a 5 g / L NaOH solution at 60°C for 30 minutes.

[0013] Preferably, in step 3, the UV-resistant finishing solution is composed of 1.5 wt% chitosan solution, 2 wt% nano zinc oxide and 1 wt% tea polyphenol extract. The UV-resistant finishing solution impregnation step involves immersing the alkali-treated cotton fibers and polylactic acid fibers in the UV-resistant finishing solution at a bath ratio of 1:15, and then shaking at 50°C for 40 minutes.

[0014] Preferably, in step 4, the solid content of the acrylic-modified waterborne polyurethane is 40%, the particle size of the nano-dioxide is 20 nm, the rotation speed of the high-speed dispersion process is 2000 rpm, the high-speed dispersion time is 30 min, and the amount of aziridine-blocked polyisocyanate added is 1 wt%.

[0015] Preferably, in step 5, the ultrasonic frequency in the ultrasonic spot welding is 20kHz, the welding pressure is 0.3MPa, the spot spacing is 5cm×5cm, and the spot diameter is 2mm, ensuring an interlayer bonding force ≥80N. The coating machine applies a coating adhesive at a rate of 8g / m², and the drying is performed using hot air circulation at a temperature of 60℃ for 10-15 minutes. The coating adhesive also contains 0.5-1wt% tea polyphenol extract, which synergistically enhances antioxidant properties with berberine extract powder.

[0016] Preferably, in step 5, the coating adhesive is directly applied to the outermost surface of the stacked fabric using a doctor blade coating machine. During operation, the three layers of fabric—outer layer, functional interlayer, and inner layer—are laid flat on the coating machine. The doctor blade applies the coating adhesive evenly to the upper surface of the outer layer fabric at a pressure of 0.35 MPa and a speed of 12 m / min, forming a continuous functional coating. The inner layer fabric is ultrasonically spot-welded to the outer / functional interlayer at the edges, while the middle portion remains independent to ensure unobstructed moisture permeability. The coating adhesive forms a functional layer only on the outer surface, avoiding reduced air permeability caused by interlayer coating, and simultaneously achieving indirect bonding with the functional interlayer through a permeation mechanism.

[0017] This invention achieves synergistic optimization of environmental friendliness, functionality, and comfort through multi-level structural design and material innovation.

[0018] First, the outer fabric uses a precise ratio of cotton fiber, polylactic acid fiber and bamboo fiber. Cotton fiber gives it natural skin-friendliness and moisture absorption and breathability, polylactic acid fiber is a biodegradable material to improve environmental friendliness, and bamboo fiber enhances hygiene performance through natural antibacterial components. Combined with a 3 / 1 warp-face right twill weave, it maintains the fabric porosity while ensuring structural strength, laying the foundation for the breathability of subsequent functional layers.

[0019] The functional interlayer uses electrospinning technology to uniformly load zinc oxide nanoparticles onto polylactic acid nanofiber membranes, which avoids the pore blockage problem caused by traditional coating processes and utilizes the high specific surface area of ​​nanoparticles to achieve efficient ultraviolet shielding. The UPF value can reach 50+ and the attenuation rate is less than 5% after 50 water washes.

[0020] After the inner fabric undergoes alkali treatment to remove impurities from the fiber surface, it is impregnated with an anti-UV finishing solution containing chitosan, nano-zinc oxide, and tea polyphenols. Combined with ultrasonic treatment, this promotes the penetration of functional particles into the fiber interior, forming an anti-UV protection system from the inside out, creating a double barrier with the interlayer. The coating adhesive uses a composite system of acrylic-modified waterborne polyurethane and berberine extract, with the addition of nano-titanium dioxide to enhance photocatalytic self-cleaning ability. A aziridine crosslinking agent ensures a strong bond between the coating and the substrate. The coating amount is only 8g / m², and the cured thickness is controlled at 0.02-0.05mm, ensuring functional durability while avoiding the reduced breathability caused by traditional coatings.

[0021] Finally, the three-layer structure is composited by ultrasonic spot welding. The spot welding pressure of 0.3MPa ensures edge sealing while retaining the moisture permeability channel in the middle area. The overall process improves the UV resistance while increasing the air permeability to 6500g / m2·24h. The tensile strength is ≥220N in the warp direction and ≥180N in the weft direction. After 50 water washes, the functional retention rate is over 90%, achieving an organic unity of high protection, high comfort, and high environmental protection. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing an environmentally friendly UV-resistant composite fabric, comprising the following steps.

[0025] Step 1: Preparation of outer fabric. Cotton fiber, polylactic acid fiber and bamboo fiber with a mass ratio of 25:60:15 are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The outer fabric with a warp and weft density of 200 ends / 10cm × 180 ends / 10cm is woven on an air-jet loom using a 3 / 1 warp right twill weave.

[0026] Step 2: Preparation of functional sandwich: Zinc oxide nanoparticles with a particle size of 30-50 nm are mixed with 8 wt% polylactic acid solution at a mass ratio of 3:100. The mixture is then used to prepare a nanofiber membrane by electrospinning. The electrospinning voltage is 15 kV and the receiving distance is 17 cm. The prepared nanofiber membrane has a fiber diameter of 200 nm and a membrane thickness of 0.05 mm.

[0027] Step 3: Preparation of the inner layer fabric. Cotton fibers and polylactic acid fibers with a mass ratio of 25:75 are treated with alkali (the alkali treatment step is to put the cotton fibers and polylactic acid fibers into a 5g / L NaOH solution and soak them at 60℃ for 30min) for 5min, and then immersed in an anti-UV finishing solution (the anti-UV finishing solution is composed of 1.5wt% chitosan solution, 2wt% nano zinc oxide and 1wt% tea polyphenol extract. The anti-UV finishing solution immersion step is to soak the alkali-treated cotton fibers and polylactic acid fibers in the anti-UV finishing solution at a bath ratio of 1:15 and then vibrate at 50℃ for 40min). Then, the functional particles are penetrated by ultrasonic treatment at 28kHz. After drying at 65℃ for 13min, 18tex yarn is spun and the inner layer fabric with a warp and weft density of 180 ends / 10cm × 160 ends / 10cm is woven on a rapier loom using a plain weave.

[0028] Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane with a solid content of 40% is mixed with berberine extract powder at a mass ratio of 92:8. Then, nano-titanium dioxide with a particle size of 20nm is added to the mixture and dispersed at a high speed of 2000rpm for 30min. Then, 1wt% of aziridine blocked polyisocyanate is added and stirring is continued for 15min.

[0029] Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are stacked sequentially. The four sides are fixed by ultrasonic spot welding at a frequency of 20kHz and a spot welding pressure of 0.3MPa. The coating adhesive is directly applied to the outermost surface of the stacked fabric using a scraper-type coating machine. During operation, the stacked outer-functional interlayer-inner fabric is laid flat on the coating machine. The scraper applies the coating adhesive evenly to the upper surface of the outer fabric at a pressure of 0.35MPa and a speed of 12m / min, forming a continuous functional coating. The amount of coating adhesive applied is 8g / m2. It is cured at 80℃ for 3min. After cooling, it is washed with water and dried with hot air circulation at 60℃ for 13min to obtain the finished product.

[0030] The environmentally friendly UV-resistant composite fabric prepared in Example 1 achieves multiple breakthroughs compared to traditional materials: In terms of protective performance, through the synergistic effect of the zinc oxide nanofiber interlayer and the surface nano-titanium dioxide coating, the UV protection factor (UPF) reaches 50+, far exceeding the UPF≤30 of pure cotton fabric, and the functional retention rate is still over 90% after 50 standard washes, overcoming the defects of traditional UV-resistant coatings that are easy to peel off and have poor durability; In terms of environmental friendliness, the entire process uses a water-based system (such as acrylic acid with a solid content of 40%). Modified polyurethane and an 80℃ low-temperature curing process bring VOC emissions close to zero, completely avoiding the risk of formaldehyde residue exceeding 75ppm in solvent-based coatings. Meanwhile, polylactic acid fiber accounts for more than 60% (outer layer) and 75% (inner layer), significantly improving biodegradability. In terms of comfort optimization, the unique ultrasonic spot welding composite structure enables a moisture permeability of up to 6500g / m2·24h, which is more than twice that of traditional hot melt adhesive composite fabrics (usually <3000g / m2·24h), solving the problem of stuffiness.

[0031] Example 2

[0032] A method for preparing an environmentally friendly UV-resistant composite fabric, comprising the following steps.

[0033] Step 1: Preparation of outer fabric. Cotton fiber, polylactic acid fiber and bamboo fiber with a mass ratio of 25:60:15 are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The outer fabric with a warp and weft density of 200 ends / 10cm × 180 ends / 10cm is woven on an air-jet loom using a 3 / 1 warp right twill weave.

[0034] Step 2: Preparation of functional sandwich: Zinc oxide nanoparticles with a particle size of 30-50 nm are mixed with 8 wt% polylactic acid solution at a mass ratio of 3:100. The mixture is then used to prepare a nanofiber membrane by electrospinning. The electrospinning voltage is 15 kV and the receiving distance is 15 cm. The prepared nanofiber membrane has a fiber diameter of 150 nm and a membrane thickness of 0.05 mm.

[0035] Step 3: Preparation of the inner layer fabric. Cotton fibers and polylactic acid fibers with a mass ratio of 25:75 are treated with alkali (the alkali treatment step is to put the cotton fibers and polylactic acid fibers into a 5g / L NaOH solution and soak them at 60℃ for 30min) for 5min, and then immersed in an anti-UV finishing solution (the anti-UV finishing solution is composed of 1.5wt% chitosan solution, 2wt% nano zinc oxide and 1wt% tea polyphenol extract. The anti-UV finishing solution immersion step is to soak the alkali-treated cotton fibers and polylactic acid fibers in the anti-UV finishing solution at a bath ratio of 1:15, and then vibrate at 50℃ for 40min). Then, the functional particles are promoted to penetrate by ultrasonic treatment at 28kHz. After drying at 60℃ for 12min, 18tex yarn is spun and the inner layer fabric with a warp and weft density of 180 ends / 10cm × 160 ends / 10cm is woven on a rapier loom using a plain weave.

[0036] Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane with a solid content of 40% is mixed with berberine extract powder at a mass ratio of 92:8. Then, nano-titanium dioxide with a particle size of 20nm is added to the mixture and dispersed at a high speed of 2000rpm for 30min. Then, 1wt% of aziridine blocked polyisocyanate is added and stirring is continued for 15min.

[0037] Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are stacked sequentially. The four sides are fixed by ultrasonic spot welding at a frequency of 20kHz and a spot welding pressure of 0.3MPa. The coating adhesive is directly applied to the outermost surface of the stacked fabric using a scraper-type coating machine. During operation, the stacked outer-functional interlayer-inner fabric is laid flat on the coating machine. The scraper applies the coating adhesive evenly to the upper surface of the outer fabric at a pressure of 0.35MPa and a speed of 12m / min, forming a continuous functional coating. The amount of coating adhesive applied is 8g / m2. It is cured at 80℃ for 3min. After cooling, it is washed with water and dried with hot air circulation at 60℃ for 10min to obtain the finished product.

[0038] Example 3

[0039] A method for preparing an environmentally friendly UV-resistant composite fabric, comprising the following steps.

[0040] Step 1: Preparation of outer fabric. Cotton fiber, polylactic acid fiber and bamboo fiber with a mass ratio of 25:60:15 are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The outer fabric with a warp and weft density of 200 ends / 10cm × 180 ends / 10cm is woven on an air-jet loom using a 3 / 1 warp right twill weave.

[0041] Step 2: Preparation of functional sandwich: Zinc oxide nanoparticles with a particle size of 30-50 nm are mixed with 8 wt% polylactic acid solution at a mass ratio of 3:100. The mixture is then used to prepare a nanofiber membrane by electrospinning. The electrospinning voltage is 15 kV and the receiving distance is 20 cm. The prepared nanofiber membrane has a fiber diameter of 250 nm and a membrane thickness of 0.05 mm.

[0042] Step 3: Preparation of the inner layer fabric. Cotton fibers and polylactic acid fibers with a mass ratio of 25:75 are treated with alkali (the alkali treatment step is to put the cotton fibers and polylactic acid fibers into a 5g / L NaOH solution and soak them at 60℃ for 30min) for 5min, and then immersed in an anti-UV finishing solution (the anti-UV finishing solution is composed of 1.5wt% chitosan solution, 2wt% nano zinc oxide and 1wt% tea polyphenol extract. The anti-UV finishing solution immersion step is to soak the alkali-treated cotton fibers and polylactic acid fibers in the anti-UV finishing solution at a bath ratio of 1:15 and then vibrate at 50℃ for 40min). Then, the functional particles are penetrated by ultrasonic treatment at 28kHz. After drying at 70℃ for 15min, 18tex yarn is spun and the inner layer fabric with a warp and weft density of 180 ends / 10cm × 160 ends / 10cm is woven on a rapier loom using a plain weave.

[0043] Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane with a solid content of 40% is mixed with berberine extract powder at a mass ratio of 92:8. Then, nano-titanium dioxide with a particle size of 20nm is added to the mixture and dispersed at a high speed of 2000rpm for 30min. Then, 1wt% of aziridine blocked polyisocyanate is added and stirring is continued for 15min.

[0044] Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are stacked sequentially. The four sides are fixed by ultrasonic spot welding at a frequency of 20kHz and a spot welding pressure of 0.3MPa. The coating adhesive is directly applied to the outermost surface of the stacked fabric using a scraper-type coating machine. During operation, the stacked outer-functional interlayer-inner fabric is laid flat on the coating machine. The scraper applies the coating adhesive evenly to the upper surface of the outer fabric at a pressure of 0.35MPa and a speed of 12m / min, forming a continuous functional coating. The amount of coating adhesive applied is 8g / m2. It is cured at 80℃ for 3min. After cooling, it is washed with water and dried with hot air circulation at 60℃ for 15min to obtain the finished product.

[0045] Example 4

[0046] A method for preparing an environmentally friendly UV-resistant composite fabric, comprising the following steps.

[0047] Step 1: Preparation of outer fabric. Cotton fiber, polylactic acid fiber and bamboo fiber with a mass ratio of 25:60:15 are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The outer fabric with a warp and weft density of 200 ends / 10cm × 180 ends / 10cm is woven on an air-jet loom using a 3 / 1 warp right twill weave.

[0048] Step 2: Preparation of functional sandwich: Zinc oxide nanoparticles with a particle size of 30-50 nm are mixed with 8 wt% polylactic acid solution at a mass ratio of 3:100. The mixture is then used to prepare a nanofiber membrane by electrospinning. The electrospinning voltage is 15 kV and the receiving distance is 18 cm. The prepared nanofiber membrane has a fiber diameter of 210 nm and a membrane thickness of 0.05 mm.

[0049] Step 3: Preparation of the inner layer fabric. Cotton fibers and polylactic acid fibers with a mass ratio of 25:75 are treated with alkali (the alkali treatment step is to put the cotton fibers and polylactic acid fibers into a 5g / L NaOH solution and soak them at 60℃ for 30min) for 5min, and then immersed in an anti-UV finishing solution (the anti-UV finishing solution is composed of 1.5wt% chitosan solution, 2wt% nano zinc oxide and 1wt% tea polyphenol extract. The anti-UV finishing solution immersion step is to soak the alkali-treated cotton fibers and polylactic acid fibers in the anti-UV finishing solution at a bath ratio of 1:15, and then vibrate at 50℃ for 40min). Then, the functional particles are penetrated by ultrasonic treatment at 28kHz. After drying at 65℃ for 14min, 18tex yarn is spun and the inner layer fabric with a warp and weft density of 180 ends / 10cm × 160 ends / 10cm is woven on a rapier loom using a plain weave.

[0050] Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane with a solid content of 40% is mixed with berberine extract powder at a mass ratio of 92:8. Then, nano-titanium dioxide with a particle size of 20nm is added to the mixture and dispersed at a high speed of 2000rpm for 30min. Then, 1wt% of aziridine blocked polyisocyanate is added and stirring is continued for 15min.

[0051] Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are sequentially stacked. Ultrasonic spot welding at a frequency of 20kHz and a welding pressure of 0.3MPa is used to fix the four sides. The coating adhesive is directly applied to the outermost surface of the stacked fabric using a scraper-type coating machine. During operation, the stacked outer-functional interlayer-inner layer fabric is laid flat on the coating machine. The scraper applies the coating adhesive evenly to the upper surface of the outer fabric at a pressure of 0.35MPa and a speed of 12m / min, forming a continuous functional coating. The coating adhesive application rate is 8g / m². 2After curing at 80℃ for 3 minutes, the product is obtained by cooling, washing with water, and drying with hot air circulation at 60℃ for 12 minutes.

[0052] Comparative Example 1

[0053] The process in step 2 was modified by using a traditional padding method instead of electrospinning to prepare the functional layer. Zinc oxide nanoparticles of the same proportion were directly dispersed in a polylactic acid solution and then coated onto the surface of the outer fabric. The coating thickness was 0.05 mm. All other steps and parameters were identical to those in Example 1 for preparing the composite fabric. The results showed that the nanoparticles severely agglomerated due to the lack of fiber encapsulation from electrospinning (particle size increased to 200-300 nm), resulting in a 40% decrease in UV shielding (UPF only 28). Furthermore, the coating blocked the fabric pores, causing the moisture permeability to plummet to 2800 g / m². 2 • After 24 hours and 20 washes, the UV protection function is completely lost. At the same time, due to the weak adhesion between the coating and the substrate, the warp breaking strength of the fabric is reduced by 25%.

[0054] Comparative Example 2

[0055] In step 4, the aziridine-blocked polyisocyanate was removed from the coating adhesive preparation process, and a traditional solvent-based toluene diisocyanate (TDI) crosslinking agent (1 wt%) was used instead. The mixture was cured at 140°C, with all other steps and parameters identical to those in Example 1, resulting in the composite fabric. The results showed that high temperature caused the polylactic acid fiber molecular chains to break, reducing the weft strength of the fabric to 155 N. Furthermore, TDI released 82 ppm of free formaldehyde (exceeding the EU limit of 75 ppm), and VOC emissions exceeded 400 μg / g. In contrast, Example 1 showed no formaldehyde detection and VOC levels close to zero after curing at 80°C.

[0056] Comparative Example 3

[0057] The composite process in step 5 was simplified by eliminating ultrasonic spot welding and the independent functional sandwich design. The three layers of materials were bonded together across the entire width using hot melt adhesive at 150°C (adhesive layer thickness 0.1 mm). The remaining steps and parameters were completely consistent with those in Example 1 to prepare the composite fabric. The results showed that this structure completely sealed the moisture permeability channels, resulting in a moisture permeability of only 1200 g / m². 2 • 24h (less than 1 / 5 of Example 1), and the hot melt adhesive caused the bamboo fiber to carbonize due to high temperature pressing, resulting in yellow spots on the surface, uneven UV resistance (UPF fluctuation range 20-45), and the interlayer peel strength decreased by 60% after 10 washes.

[0058] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly UV-resistant composite fabric, characterized in that: The steps are as follows: Step 1: Outer fabric preparation. Cotton fiber, polylactic acid fiber and bamboo fiber are opened, mixed and carded, and then spun into 20tex blended yarn on a ring spinning machine. The fabric is woven on an air-jet loom using a twill weave. Step 2: Preparation of functional sandwich layer: Zinc oxide nanoparticles and polylactic acid solution are mixed at a mass ratio of 3:100, and nanofiber membranes are prepared by electrospinning device; Step 3: Inner layer fabric preparation: Cotton fibers and polylactic acid fibers are treated with alkali and then immersed in an anti-UV finishing solution. Subsequently, ultrasonic treatment is used to promote the penetration of functional particles. After drying, 18tex yarn is spun and woven on a rapier loom using a plain weave structure. Step 4: Preparation of coating adhesive. Acrylic modified waterborne polyurethane and berberine extract powder are mixed at a mass ratio of 92:

8. Then, nano titanium dioxide is added to the mixture for high-speed dispersion. Aziridine blocked polyisocyanate is added and stirring is continued for 15 minutes. Step 5: Composite process. The outer fabric, functional interlayer, and inner fabric are stacked in sequence, and the four sides are fixed by ultrasonic spot welding. The coating adhesive is applied by a scraper coating machine, cured at 80°C for 3 minutes, and after cooling, washed and dried to obtain the finished product.

2. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 1, the mass ratio of cotton fiber, polylactic acid fiber and bamboo fiber in the outer fabric is 25:60:15, the twill weave is 3 / 1 warp right twill, and the warp and weft density of the woven outer fabric is 200 threads / 10cm × 180 threads / 10cm.

3. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 2, the zinc oxide nanoparticles have a particle size of 30-50 nm, the polylactic acid concentration is 8 wt%, the electrospinning voltage is 15 kV, the electrospinning receiving distance is 15-20 cm, the nanofiber membrane has a fiber diameter of 150-250 nm, and the nanofiber membrane thickness is 0.05 mm.

4. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 3, the mass ratio of cotton fiber to polylactic acid fiber is 25:75, the ultrasonic treatment parameters are: ultrasonic power set to 28kHz, ultrasonic time 5min, the drying temperature is 65℃±5℃, the drying time is 12-15min, and the warp and weft density of the woven inner fabric is 180 threads / 10cm×160 threads / 10cm.

5. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 3, the alkali treatment step involves immersing cotton fibers and polylactic acid fibers in a 5 g / L NaOH solution at 60°C for 30 minutes.

6. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 3, the UV-resistant finishing solution is composed of 1.5 wt% chitosan solution, 2 wt% nano zinc oxide and 1 wt% tea polyphenol extract. The UV-resistant finishing solution impregnation step involves immersing the alkali-treated cotton fibers and polylactic acid fibers in the UV-resistant finishing solution at a bath ratio of 1:15, and then shaking at 50°C for 40 minutes.

7. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 4, the solid content of the acrylic-modified waterborne polyurethane is 40%, the particle size of the nano-dioxide is 20nm, the speed of the high-speed dispersion process is 2000rpm, the high-speed dispersion time is 30min, and the amount of aziridine-blocked polyisocyanate added is 1wt%.

8. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 5, the ultrasonic frequency in the ultrasonic spot welding is 20kHz, the welding pressure is 0.3MPa, and the coating amount of the coating adhesive applied by the coating machine is 8g / m². 2 The drying process employs hot air circulation, with a drying temperature of 60°C and a drying time of 10-15 minutes.

9. The method for preparing an environmentally friendly UV-resistant composite fabric according to claim 1, characterized in that: In step 5, the coating adhesive is directly applied to the outermost surface of the stacked fabric using a scraper-type coating machine. During operation, the stacked outer layer, functional interlayer, and inner layer fabrics are laid flat on the coating machine, and the scraper applies the coating adhesive evenly to the upper surface of the outer fabric at a pressure of 0.35 MPa and a speed of 12 m / min to form a continuous functional coating.