A water-based PU waterproof and moisture-permeable membrane for outdoor clothing and a film forming process

Abstract

The application discloses a water-based PU waterproof and moisture-permeable membrane for outdoor clothes and a film forming process, and relates to the technical field of functional clothes fabric membrane material processing.The application uses environmentally-friendly water-based PU resin as a core raw material, matches auxiliary additives with optimized proportions, and combines a special film forming process to replace a traditional solvent-based PU film forming system.The application solves the problems of poor stability and insufficient adhesion to outdoor clothes fabric of the existing water-based PU membrane by precisely optimizing the water-based PU resin formula system and the mass production film forming process parameters, and the prepared water-based PU waterproof and moisture-permeable membrane has no organic solvent residue and low VOC emission, the production process is safe, flame-retardant and pollution-free, the physical harm to the operators is completely eliminated, the waterproof and moisture-permeable performance is excellent, the outdoor use requirements of the outdoor clothes are fully met, the mass production can be realized, the traditional solvent-based PU membrane and low-end TPU membrane are replaced, and the cost performance and environmental protection are better than those of high-end PTFE membrane, so that the application has high market promotion value.

Description

Technical Field

[0001] This invention belongs to the field of functional clothing membrane material processing technology, specifically relating to a water-based PU waterproof and breathable membrane for outdoor clothing and its film-forming process. Background Technology

[0002] Currently, waterproof and breathable membranes for outdoor functional clothing such as rain jackets are mainly divided into three categories: high-end PTFE membranes, mid-range solvent-based PU membranes, and low-end TPU membranes. Each type of membrane material has its own advantages and disadvantages, and is suitable for different levels of rain jacket production needs. Among them, PTFE membranes have excellent overall performance, but their production cost is extremely high, making it difficult to achieve large-scale widespread application; TPU membranes are inexpensive, but their waterproof and breathable stability is poor and their weather resistance is insufficient, making them only suitable for low-end outdoor clothing; solvent-based PU membranes are currently the mainstream membrane material used in mid-range rain jackets, offering moderate cost-effectiveness and balanced physical properties, and are the most widely used waterproof and breathable membrane material in the market.

[0003] However, the PU films currently in mass production all use solvent-based resin systems, which have many inherent technical defects and industry pain points: First, they are not environmentally friendly, as the production process releases a large amount of organic solvents, resulting in excessive VOC emissions and pollution of the ecological environment; Second, they have low production safety, as organic solvents are flammable and explosive, posing significant safety hazards throughout the production, storage, and processing processes, and easily leading to safety accidents; Third, they are not user-friendly, as organic solvents are highly irritating, and long-term exposure can seriously damage the respiratory tract, skin, and other bodily functions of operators, endangering occupational health, and also leading to difficulties in recruiting workers and high staff turnover in the industry; Fourth, the finished products are not environmentally friendly, with trace amounts of organic solvents remaining in the film, which does not conform to the current trend of green production and low-carbon environmental protection in the garment industry; Fifth, they have high energy consumption, as the drying and curing processes of solvent-based systems consume a lot of energy, resulting in high production costs.

[0004] To address the numerous shortcomings of solvent-based PU films, the industry has gradually begun research and development on water-based PU films. Water-based systems use pure water as the dispersion medium, which can fundamentally avoid a series of problems such as environmental pollution, safety hazards, and human harm caused by organic solvents. It is the optimal technical route to replace solvent-based PU films. However, the existing water-based PU film technology on the market is still in the initial development and trial production stage, and has not yet formed a mature formulation system and mass production process, with many technical shortcomings: First, the resin selection is not matched, and general-purpose water-based PU resins are mostly used, without being customized for the special needs of outdoor jackets for water resistance, high and low temperature resistance, high moisture permeability, and high water pressure, resulting in insufficient functionality of the finished product; Second, the ratio of additives is unreasonable, and the synergy of various functional components is poor, resulting in mutual constraints between waterproof and moisture permeability, insufficient film flexibility, and weak fabric adhesion; Third, the film-forming process is crude, and single-stage high-temperature drying and one-time stirring processes are mostly used, which easily leads to residual air bubbles in the liquid, pinhole cracks in the film, and insufficient resin cross-linking, resulting in uneven physical properties and poor stability of the finished product; Fourth, the mass production adaptability is poor, and the existing technology can only be used for small-batch trial production. The yield rate of continuous production is low and the performance consistency is poor, making it unsuitable for large-scale production line processing applications of downstream outdoor jackets.

[0005] In summary, the industry urgently needs to develop a dedicated water-based PU waterproof and breathable membrane and its supporting film-forming process that is specifically adapted to the application scenarios of outdoor jackets, has precise and controllable formula parameters, mature and stable film-forming technology, and can be mass-produced on a large scale. This would solve the pain points of traditional solvent-based membranes, such as poor environmental performance and low safety, while also breaking through the technical bottlenecks of insufficient performance and inability to mass-produce existing water-based PU membranes. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a water-based PU waterproof and breathable membrane and film-forming process for outdoor clothing. This solves the problems of traditional solvent-based PU membranes being environmentally unfriendly, unsafe, harmful to human health, and energy-intensive. At the same time, it overcomes the technical bottlenecks of existing water-based PU membrane formulations being immature, unable to be mass-produced, and having poor application adaptability, thereby achieving stable mass production of water-based PU membranes and large-scale application in the field of outdoor clothing.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A water-based PU waterproof and breathable membrane for outdoor clothing, comprising, by weight percentage: 65%–85% water-based polyurethane resin, 3%–8% waterproofing agent, 2%–6% breathability agent, 1%–3% flexibility and toughening agent, 0.5%–1.5% wetting and leveling agent, 1.5%–3% matting agent, and the balance being deionized water; the water-based PU waterproof and breathable membrane is prepared entirely using a pure water system, without adding any organic solvents such as toluene, xylene, methyl ethyl ketone, or ethyl acetate, and has zero VOC toxic solvent components. It is suitable for composite processing of various woven and knitted fabrics for outdoor clothing, and possesses high waterproof, high breathability, washability, weather resistance, and anti-aging properties.

[0008] Preferably, the waterborne polyurethane resin is an anionic aliphatic waterborne PU resin with a solid content of 40% to 50%, a viscosity controlled at 200 to 800 mPa·s (25℃), a glass transition temperature Tg of -35℃ to -20℃, an elongation at break ≥600%, a tensile strength ≥25MPa, and resistance to low-temperature bending without cracking, making it suitable for outdoor rain jackets used in high and low temperature alternating environments.

[0009] Preferably, the waterproofing functional additive is one or a combination of two of the following: fluorinated modified acrylic waterproofing additive or organosilicon waterproofing additive, with a particle size of 50-200 nm, possessing low surface tension characteristics, and can form a dense hydrophobic layer on the membrane surface to improve static waterproof water pressure; the moisture-permeable functional additive is a polyether-type hydrophilic moisture-permeable additive, with a molecular chain containing a hydrophilic block structure, which can construct microporous moisture-permeable channels to achieve unidirectional water vapor permeation and liquid water barrier.

[0010] Preferably, the flexible toughening agent is a water-based polyurethane elastic toughening agent, used to improve the film's flexibility and adhesion to the fabric, preventing the film from peeling or cracking after bending or rubbing; the wetting and leveling agent is a polyether-modified silicone leveling agent, which can improve the uniformity of water-based liquid coating, eliminate pinholes, craters, and orange peel defects, and improve the smoothness and density of the film; the matting powder is ultrafine silica powder.

[0011] Preferably, the finished thickness of the water-based PU waterproof and breathable membrane is 0.01-0.05mm, the water pressure is ≥8000mmH2O, the moisture permeability is ≥8000g / (m²·24h), and the waterproof and breathable performance degradation rate after 20 washes is ≤8%, which fully meets the functional requirements of the GB / T 32614-2016 national standard for outdoor jackets.

[0012] A film-forming process for a water-based PU waterproof and breathable membrane for outdoor clothing includes the following steps: Step S1, Raw material pretreatment: Select qualified anionic aliphatic waterborne PU resin, filter it under pressure using a 100-200 mesh filter to remove impurities and gel particles inside the resin, and let it stand at room temperature (25℃) for 10-20 minutes to eliminate micro-bubbles generated during raw material storage; select waterborne PU resin suitable for the waterproof and breathable requirements of outdoor clothing, screen raw materials that meet the standards for purity, viscosity, and solid content, remove impurities and bubbles inside the raw materials, and ensure the stability of the raw materials; Step S2, Precise Proportioning and Mixing: Precise proportioning and mixing: Deionized water, wetting and leveling agent, flexibility and toughening agent, moisture-permeable agent, and waterproof agent are added sequentially according to the formula mass percentage. After low-speed pre-stirring, water-based PU resin is added, and a uniform liquid is prepared using a segmented gradient stirring process. The water-based PU resin and functional additives are mixed according to the optimized proportion, and a segmented uniform speed stirring process is used to ensure that all components are uniformly integrated and to avoid agglomeration and stratification. Step S3, Vacuum Defoaming and Settling: The mixed liquid is put into a vacuum defoaming tank and defoamed for 5 to 10 minutes under a vacuum of -0.06 to -0.09 MPa. Then, it is left to stand at room temperature in a sealed environment for 15 to 25 minutes to completely eliminate microbubbles in the system. The mixed liquid is left to stand and defoam to remove microbubbles generated during the stirring process, prevent pinholes and cracks after film formation, and ensure the smoothness and density of the film. Step S4, Precision Coating Film Formation: Using slit coating or roller coating processes, the defoamed liquid is evenly coated onto the surface of the release substrate, and the wet film thickness is controlled to be 0.08-0.15mm; using precision coating processes, the treated liquid is evenly coated onto the surface of the substrate, and the coating thickness is controlled to meet the bonding requirements of the waterproof jacket fabric. Step S5, Multi-stage Gradient Drying and Curing: The coated film is fed into a thermal oil furnace for heating and drying. A three-stage gradient heating and drying process is adopted to sequentially complete low-temperature pre-drying, medium-temperature cross-linking and curing, and high-temperature shaping. The waste gas generated during the drying process is treated and discharged using RTO waste gas treatment. The gradient heating and drying process achieves resin cross-linking and film formation, avoiding the problems of film cracking and decreased moisture permeability caused by rapid drying. The use of RTO waste gas treatment has high heat recovery efficiency, high temperature resistance, corrosion resistance, long service life and replacement cycle, low operating cost, and the final product has no hazardous waste, no wastewater, and no by-products, making it environmentally friendly. Step S6, Constant Temperature Cooling and Shaping: After drying and curing, use uniform air cooling to cool, controlling the cooling rate to 3-5℃ / min. After cooling to room temperature of 25℃, keep it at a constant temperature for 20-30 minutes to shape. After drying, cool naturally at a uniform speed to stabilize the film structure. Finally, roll it up neatly to obtain the finished water-based PU waterproof and breathable film.

[0013] Step S7, winding and post-processing: After the shaping is completed, the film is wound up smoothly, and the winding tension is kept constant to avoid wrinkles and stretching deformation, so as to obtain the finished water-based PU waterproof and breathable membrane.

[0014] Preferably, the S2 segmented gradient stirring process specifically involves: first, stirring at a low speed of 200–300 r / min for 8–12 min to achieve initial dispersion of the additives; then, stirring at a medium speed of 500–600 r / min for 20–30 min to achieve uniform compatibility of the components; and finally, stirring at a low speed of 350–400 r / min for 5–8 min to eliminate eddy bubbles generated by high-speed stirring, ensuring that the liquid system is uniform, stable, and free from stratification and agglomeration.

[0015] Preferably, the specific parameters of the S5 multi-stage gradient drying and curing process are as follows: the first stage is a low-temperature pre-drying temperature of 55-65℃ and a drying time of 6-10 min, which slowly removes free water from the surface of the liquid and avoids rapid skinning on the surface; the second stage is a medium-temperature curing temperature of 85-95℃ and a drying time of 10-15 min, which promotes the cross-linking reaction of resin molecular chains and forms a stable micro-network structure; the third stage is a high-temperature setting temperature of 105-115℃ and a drying time of 4-6 min, which completes the densification and setting of the film and improves the mechanical properties and water resistance of the film.

[0016] Preferably, the environmental parameters of the coating process are controlled as follows: ambient temperature 22-28℃, ambient humidity 40%-60%, and dust-free class 10,000 to avoid dust adhering to the film surface and causing performance defects, and to ensure film formation consistency and yield.

[0017] Preferably, the film-forming process uses pure water as the dispersion medium throughout, with no addition or volatilization of organic solvents. The VOC emissions during the production process are extremely low, the production equipment does not require explosion-proof modification, the production system is non-flammable and non-explosive, and there is no release of toxic or irritating gases. By precisely proportioning the formulation system and synergistically coupling the multi-stage gradient film-forming process, the technical defects of traditional water-based PU films, such as uneven film formation, numerous pinholes and bubbles, weak adhesion, poor water washability, and low mass production stability, are solved, achieving continuous and large-scale industrial mass production with a mass production yield of ≥98%.

[0018] Preferably, after the water-based PU waterproof and breathable membrane is prepared by the film-forming process of the present invention, the finished product has no organic solvent residue and meets the textile environmental protection standards; the production process is low-energy and low-pollution, completely eliminating the irritation and harm of organic solvents to the respiratory tract and skin of operators, improving the working environment, and reducing the difficulty of enterprise recruitment and safety production management costs.

[0019] The core innovation of this invention lies in the synergistic coupling design of a customized water-based PU formulation system and a multi-stage gradient controllable film-forming process. This dual-dimensional optimization, specifically for outdoor jacket applications, overcomes existing technological bottlenecks. Compared to traditional solvent-based PU films and existing immature water-based PU technologies, it possesses significant technical advantages and beneficial effects, as detailed below: 1. Extremely environmentally friendly and green production: This invention uses a water-based system throughout the entire process, with no organic solvents added or used. The production process has low VOCs and zero emissions of toxic pollutants, and does not pollute the surrounding ecological environment. The finished film has no organic solvent residue, which meets the environmental protection standards of high-end outdoor clothing. Compared with traditional solvent-based PU films, the environmental performance is greatly improved.

[0020] 2. Production safety with no safety hazards: The water-based system is non-flammable and non-explosive, completely eliminating the safety risks of flammability and explosion associated with traditional solvent-based systems, significantly reducing enterprise safety management costs, and ensuring a safe and stable production process.

[0021] 3. Protect workers' health and reduce recruitment difficulties: The production process does not involve the volatilization of irritating organic solvents, which will not harm the skin or respiratory tract of operators. It completely solves the occupational health hazards of traditional processes, improves the working environment, and effectively solves the problems of difficulty in recruiting workers and high employee turnover in the industry.

[0022] 4. Lower energy consumption and cost savings: Compared with the high-temperature and high-energy-consumption drying process of solvent-based PU film, the water-based system segmented drying process of this invention has lower energy consumption, simplifies the process of treating production exhaust gas, and significantly reduces the production and environmental protection costs of enterprises.

[0023] 5. Stable physical properties and suitable for mass production: Through optimization of a special water-based resin formula, it precisely matches the core requirements of waterproof, breathable, tensile, and weather-resistant outdoor jackets. Combined with a dedicated film-forming process, it solves the problems of existing water-based PU film defects, uneven physical properties, and inability to be mass-produced, enabling large-scale industrial production. Downstream applications can be perfectly adapted to various outdoor clothing fabric processing applications.

[0024] 6. Excellent cost performance and wide range of alternatives: The water-based PU film prepared by this invention has better overall performance than low-end TPU film and its cost is much lower than that of high-end PTFE film. It can completely replace the existing mid-range solvent-based PU film and has extremely strong market adaptability. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the overall process structure of a water-based PU waterproof and breathable membrane for outdoor clothing and the film-forming process proposed in this invention. Detailed Implementation

[0026] The technical solution of the present invention will be further described in detail and completely below with reference to specific preferred embodiments and comparative examples. Each embodiment strictly follows the formulation system and film-forming process parameters of the present invention, and the total amount of each formulation is 100%. Unless otherwise specified, all are processed in a normal temperature and pressure environment.

[0027] Example 1 (Standard version of rain jacket with water-based PU waterproof and breathable membrane): Reference Figure 1 As shown, this embodiment provides a water-based PU waterproof and breathable membrane for a regular commuter-style windbreaker, with the following formula by weight percentage: 75% water-based polyurethane resin, 5% silicone waterproofing agent, 4% polyether-type hydrophilic and breathable agent, 2% water-based polyurethane elastic toughening agent, 1% polyether-modified silicone leveling agent, 2% matting powder, and 11% deionized water.

[0028] The specific steps and precise parameters of the film formation process in this embodiment are as follows: Step S1, Raw material pretreatment: Select anionic aliphatic waterborne PU resin with a solid content of 45%, a viscosity of 500 mPa·s (25℃), and a Tg of -28℃. Use a 150-mesh filter under pressure to remove impurities and gel particles from the resin. Let it stand at room temperature (25℃) for 15 minutes to eliminate micro-bubbles generated during the raw material storage process.

[0029] Step S2, Segmented Gradient Mixing: Add deionized water, silicone waterproofing agent, polyether hydrophilic and breathable agent, waterborne polyurethane elastic toughening agent, polyether modified silicone leveling agent, and matting agent in sequence according to the formula ratio. First, pre-stir at a low speed of 250 r / min for 10 min to achieve initial dispersion of the agents. After adding the waterborne polyurethane resin, stir at a medium speed of 550 r / min for 25 min to achieve uniform compatibility of the components. Finally, stir at a low speed of 380 r / min for 6 min to eliminate eddy bubbles generated by high-speed stirring, ensuring that the system is uniformly mixed without stratification or agglomeration.

[0030] Step S3, Vacuum defoaming and settling: The mixture obtained in step S2 is put into a vacuum defoaming tank and defoamed for 8 minutes under a vacuum of -0.08MPa. After taking it out, it is settling for 20 minutes under a sealed condition at room temperature to completely eliminate microbubbles in the system.

[0031] Step S4, Precision Coating and Film Formation: In a Class 10,000 cleanroom environment with a temperature of 25℃ and a humidity of 50%, a roller coating process is used to control the wet film thickness to 0.12mm and uniformly coat the PET release film substrate.

[0032] Step S5, Multi-stage gradient drying and curing: The coated film is sent into a thermal oil furnace for heating and drying, using a three-stage gradient temperature rise drying process: the first stage is pre-drying at 60℃ for 8 minutes to remove surface free moisture; the second stage is curing at 90℃ for 12 minutes to achieve full cross-linking of the resin; the third stage is setting at 110℃ for 5 minutes to complete the densification and molding of the film. The waste gas generated during the drying process is treated and discharged using RTO waste gas treatment.

[0033] Step S6, Constant Temperature Cooling and Shaping: After drying and curing, cool the product at a constant temperature of 4℃ / min to room temperature of 25℃, let it stand at a constant temperature for 25 minutes, flatten and roll it up to obtain a finished water-based PU waterproof and breathable membrane with a thickness of 0.03mm.

[0034] Step S7, winding and post-processing: After the shaping is completed, the film is wound up smoothly, and the winding tension is kept constant to avoid wrinkles and stretching deformation, so as to obtain the finished water-based PU waterproof and breathable membrane.

[0035] The finished product test data of this embodiment are as follows: water pressure permeability 9200mmH2O, moisture permeability 9100g / (m²·24h), performance degradation rate after 20 washes 5.2%, tensile strength 28MPa, elongation at break 650%, no organic solvent residue, extremely low VOC emissions, safe and hazard-free production process, and suitable for mass production of regular commuter jackets.

[0036] Example 2 (Specifically for high-permeability, high-end outdoor jackets): This embodiment is designed for highly active outdoor scenarios such as mountain hiking and wilderness exploration. It optimizes the formula and process to improve the moisture permeability of the membrane while retaining its ultra-high waterproof performance.

[0037] Reference Figure 1 As shown, the formula of this embodiment by mass percentage is as follows: 70% waterborne polyurethane resin, 6% fluorinated modified acrylic waterproofing agent, 6% high-penetration polyether moisture-permeable agent, 2.5% waterborne polyurethane elastic toughening agent, 1.2% polyether modified silicone leveling agent, 3% matting powder, and 11.3% deionized water.

[0038] Step S1, Raw material pretreatment: Select anionic aliphatic waterborne PU resin with a solid content of 50%, a viscosity of 600 mPa·s (25℃), and a Tg of -24℃. Use a 120-mesh filter under pressure to remove impurities and gel particles from the resin. Let it stand at room temperature (25℃) for 20 minutes to eliminate micro-bubbles generated during the raw material storage process.

[0039] Step S2, Segmented Gradient Mixing: Add deionized water, fluorinated modified acrylic waterproofing agent, high-penetration polyether moisture-permeable agent, waterborne polyurethane elastic toughening agent, polyether modified silicone leveling agent, and matting agent in sequence according to the formula ratio. First, pre-stir at a low speed of 300 r / min for 12 min to achieve initial dispersion of the additives. After adding the waterborne polyurethane resin, stir at a medium speed of 600 r / min for 30 min to achieve uniform compatibility of the components. Finally, stir at a low speed of 400 r / min for 8 min to eliminate eddy bubbles generated by high-speed stirring, ensuring that the system is uniformly mixed without stratification or agglomeration.

[0040] Step S3, Vacuum Defoaming and Settling: The mixture obtained in step S2 is put into a vacuum defoaming tank and defoamed for 10 minutes under a vacuum of -0.09 MPa. After taking it out, it is settling for 25 minutes under a sealed condition at room temperature to completely eliminate microbubbles in the system.

[0041] Step S4, Precision Coating and Film Forming: In a Class 10,000 cleanroom environment with a temperature of 28℃ and a humidity of 55%, a roller coating process is used to control the wet film thickness to 0.10mm and uniformly coat the PET release film substrate.

[0042] Step S5, Multi-stage gradient drying and curing: The coated film is sent into a heat transfer oil furnace for heating and drying, using a three-stage gradient temperature rise drying process: the first stage is pre-drying at 58℃ for 9 minutes to remove surface free moisture; the second stage is curing at 92℃ for 14 minutes to achieve full cross-linking of the resin; the third stage is setting at 112℃ for 5 minutes to complete the densification and molding of the film. The waste gas generated during the drying process is treated and discharged using RTO waste gas treatment.

[0043] Step S6, Constant Temperature Cooling and Shaping: After drying and curing, cool the product at a constant temperature of 3.5℃ / min to room temperature of 25℃, let it stand at a constant temperature for 30 minutes, flatten and roll it up to obtain a finished water-based PU waterproof and breathable membrane with a thickness of 0.05mm.

[0044] Step S7, winding and post-processing: After the shaping is completed, the film is wound up smoothly, and the winding tension is kept constant to avoid wrinkles and stretching deformation, so as to obtain the finished water-based PU waterproof and breathable membrane.

[0045] The finished product test data of this embodiment are as follows: water pressure permeability 8800mmH2O, moisture permeability 11500g / (m²·24h), water attenuation rate of 6.1% after 20 washes, tensile strength 26MPa, elongation at break 720%, excellent flexibility and low temperature resistance, suitable for the use of high-end high moisture permeability outdoor jackets, and excellent mass production stability.

[0046] Example 3 (Highly water-resistant workwear and waterproof jacket) Reference Figure 1 As shown, this embodiment is designed for workwear-type rain jackets that are frequently washed and used under high intensity, enhancing the adhesion and water resistance of the membrane. The formulation, by weight percentage, is: 80% waterborne polyurethane resin, 4% fluorinated modified acrylic waterproofing agent, 3% high-penetration polyether breathable agent, 3% waterborne polyurethane elastic toughening agent, 0.8% polyether modified silicone leveling agent, 1.5% matting agent, and 7.7% deionized water.

[0047] Step S1, Raw material pretreatment: Select anionic aliphatic waterborne PU resin with a solid content of 40%, a viscosity of 350 mPa·s (25℃), and a Tg of -30℃. Use a 100-mesh filter under pressure to remove impurities and gel particles from the resin. Let it stand at room temperature (25℃) for 20 minutes to eliminate micro-bubbles generated during the raw material storage process.

[0048] Step S2, Segmented Gradient Mixing: Add deionized water, fluorinated modified acrylic waterproofing agent, high-penetration polyether moisture-permeable agent, waterborne polyurethane elastic toughening agent, polyether modified silicone leveling agent, and matting agent in sequence according to the formula ratio. First, pre-stir at a low speed of 200 r / min for 8 min to achieve initial dispersion of the additives. After adding the waterborne polyurethane resin, stir at a medium speed of 500 r / min for 20 min to achieve uniform compatibility of each component. Finally, stir at a low speed of 350 r / min for 5 min to eliminate eddy bubbles generated by high-speed stirring, ensuring that the system is uniformly mixed without stratification or agglomeration.

[0049] Step S3, Vacuum Defoaming and Settling: The mixture obtained in step S2 is put into a vacuum defoaming tank and defoamed for 7 minutes under a vacuum of -0.07MPa. After taking it out, it is settling for 20 minutes under a sealed condition at room temperature to completely eliminate microbubbles in the system.

[0050] Step S4, Precision Coating and Film Formation: In a Class 10,000 cleanroom environment with a temperature of 26℃ and a humidity of 55%, a roller coating process is used to control the wet film thickness to 0.10mm and uniformly coat the PET release film substrate.

[0051] Step S5, Multi-stage gradient drying and curing: The coated film is sent into a thermal oil furnace for heating and drying, using a three-stage gradient temperature rise drying process: the first stage is pre-drying at 62℃ for 8 minutes to remove surface free moisture; the second stage is curing at 93℃ for 15 minutes to enhance the resin crosslinking density; the third stage is setting at 113℃ for 6 minutes to complete the densification and molding of the film. The waste gas generated during the drying process is treated and discharged using RTO waste gas treatment.

[0052] Step S6, Constant Temperature Cooling and Shaping: After drying and curing, cool the product at a constant temperature of 3℃ / min to room temperature of 25℃, let it stand at a constant temperature for 30 minutes, flatten and roll it up to obtain a finished water-based PU waterproof and breathable membrane with a thickness of 0.02mm.

[0053] Step S7, winding and post-processing: After the shaping is completed, the film is wound up smoothly, and the winding tension is kept constant to avoid wrinkles and stretching deformation, so as to obtain the finished water-based PU waterproof and breathable membrane.

[0054] The finished product test data of this embodiment are as follows: water pressure permeability 9500mmH2O, moisture permeability 8200g / (m²·24h), performance degradation rate of only 3.8% after 20 washes, tensile strength 33MPa, elongation at break 580%, and water resistance and abrasion resistance are greatly improved, making it suitable for high-intensity use scenarios of workwear and windbreakers.

[0055] Compare the finished product test data from Examples 1-3: <![CDATA[Water permeability pressure (mmH2O)]]> 9200 8800 9500 Moisture permeability (g / (m²·24h)) 9100 11500 8200 Performance degradation rate after 20 washes 5.2% 6.1% 3.8% Tensile strength 28MPa 26MPa 33MPa Elongation at break 650% 720% 580% In summary, Example 1 is environmentally friendly, with no organic solvent residue and extremely low VOC emissions, and the production process is safe and hazard-free; it has a balanced performance in terms of waterproofness, breathability, mechanical properties, and washability, making it suitable for regular commuter jackets, with strong adaptability in sewing processing, and suitable for mass production; Example 2 has excellent flexibility and low-temperature resistance, outstanding fabric extensibility, and excellent mass production stability; it features ultra-high breathability while also providing basic waterproofing, making it suitable for high-end, highly breathable outdoor jackets used in cold weather, long-term hiking, and mountaineering; Example 3 has high tensile strength, strong tear resistance, extremely low performance degradation after washing, significantly improved washability and abrasion resistance, and top-tier waterproof rating, making it suitable for high-intensity, high-frequency use scenarios such as construction sites, fieldwork, and maintenance.

[0056] To fully verify the advanced nature and superiority of the technology of this invention, comparative examples 1 (traditional solvent-based PU film), 2 (existing commercially available ordinary water-based PU film), and the finished product of Example 1 of this invention were set up for parallel comparative testing. The testing environment and testing standards were unified, and the various performance and production indicators are as follows: 1. Environmental and safety indicators: Comparative Example 1: Solvent-based PU film has excessive VOC emissions, posing a risk of flammability and explosion, and the production process produces irritating gases that endanger human health; Comparative Example 2: Ordinary water-based PU film meets VOC emission standards, but has many bubbles in the film and a yield rate of only 85%; The VOC emissions of each embodiment of the present invention are reduced by more than 95%, with no risk of flammability and explosion, no occupational hazards, and a mass production yield rate of ≥98%.

[0057] 2. Functional performance indicators: Comparative Example 1: Solvent-based PU film with a water permeability pressure of 9300 mmH2O, a moisture permeability of 9000 g / (m²·24h), and a water wash degradation rate of 5.5% after 20 washes; Comparative Example 2: Ordinary water-based PU film with a water permeability pressure of 6500 mmH2O, a moisture permeability of 6800 g / (m²·24h), and a water wash degradation rate of 15.3% after 20 washes; The performance of Example 1 of this invention is comparable to that of the solvent-based PU film, and far superior to that of existing ordinary water-based PU films, with a significantly improved water wash resistance.

[0058] 3. Production energy consumption and cost: Comparative Example 1 solvent-based system has high production energy consumption, requires explosion-proof equipment and exhaust gas treatment equipment, and has high overall cost; Comparative Example 2 water-based process is immature, has low yield, and high rework cost; The process of this invention reduces energy consumption by more than 20%, does not require explosion-proof and complex exhaust gas treatment equipment, has high yield, and lower overall cost for mass production.

[0059] In summary, this invention, through synergistic optimization of formulation and process, takes into account environmental protection and safety, product performance, mass production stability and economy, and perfectly solves various pain points of existing technologies, demonstrating significant technological progress and industrialization value.

[0060] Testing revealed that the water-based PU waterproof and breathable membrane prepared by this invention reduces VOC emissions by more than 95% compared to traditional solvent-based PU membranes. The production process poses no risk of flammability or explosion, and no occupational health hazards. The finished membrane's waterproof, breathable, weather-resistant, and adhesive properties are on par with solvent-based PU membranes, fully meeting the outdoor use standards for outdoor clothing. Production energy consumption is reduced by more than 20%, and the mass production qualification rate is increased to 98%. This completely solves the technical problems of existing water-based PU membranes being unable to be mass-produced and having limited applications, demonstrating extremely high industrialization value.

[0061] The optimal implementation of this invention is the formula and process parameters described in Example 1: using 75% anionic aliphatic waterborne PU resin combined with a composite functional additive system, along with a complete film-forming process including segmented gradient stirring, vacuum defoaming, Class 10,000 cleanroom precision coating, three-stage gradient drying, and uniform cooling and shaping; this solution achieves the best balance of waterproof, breathable, washable, and mechanical properties, while also having low production energy consumption, high yield, and strong mass production stability, making it suitable for the large-scale production of most outdoor jackets. It is the optimal implementation method that takes into account performance, environmental protection, safety, and economic benefits.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The process parameters and proportions that are not described in detail in the present invention can be adapted and optimized according to the actual production equipment and fabric type, and all of them fall within the scope of the technical solution of the present invention.

Claims

1. A water-based PU waterproof and breathable membrane for a waterproof jacket, characterized in that, By weight percentage, it comprises: 65%–85% waterborne polyurethane resin, 3%–8% waterproofing agent, 2%–6% breathable agent, 1%–3% flexibility and toughening agent, 0.5%–1.5% wetting and leveling agent, 1.5%–3% matting agent, and the balance being deionized water. The waterborne PU waterproof and breathable membrane is prepared entirely using a pure water system, without adding any organic solvents such as toluene, xylene, methyl ethyl ketone, or ethyl acetate. It contains zero VOC toxic solvent components and is suitable for composite processing of various woven and knitted fabrics used in outdoor jackets. It possesses high waterproof, high breathability, washability, weather resistance, and anti-aging properties.

2. The water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 1, characterized in that, The waterborne polyurethane resin is an anionic aliphatic waterborne PU resin with a solid content of 40% to 50%, a viscosity controlled at 200 to 800 mPa·s (25℃), a glass transition temperature (Tg) of -35℃ to -20℃, an elongation at break of ≥600%, a tensile strength of ≥25MPa, and resistance to low-temperature bending without cracking, making it suitable for outdoor jackets used in high and low temperature alternating environments.

3. The water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 1, characterized in that, The waterproofing functional additive is one or a combination of two of the following: fluorinated modified acrylic waterproofing additive or organosilicon waterproofing additive. It has a particle size of 50-200 nm and low surface tension characteristics. It can form a dense hydrophobic layer on the membrane surface and improve static waterproof water pressure. The moisture-permeable functional additive is a polyether-type hydrophilic moisture-permeable additive with a molecular chain containing a hydrophilic block structure. It can construct microporous moisture-permeable channels to achieve unidirectional water vapor permeation and liquid water barrier.

4. The water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 1, characterized in that, The flexible toughening agent is a water-based polyurethane elastic toughening agent, used to improve the film's flexibility and adhesion to the fabric, preventing the film from peeling or cracking after bending or rubbing; the wetting and leveling agent is a polyether-modified silicone leveling agent, which can improve the uniformity of water-based liquid coating, eliminate pinholes, craters, and orange peel defects, and improve the smoothness and density of the film; the matting powder is ultrafine silica powder.

5. The water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 1, characterized in that, The finished thickness of the water-based PU waterproof and breathable membrane is 0.01-0.05 mm, the water pressure is ≥8000 mmH2O, the moisture permeability is ≥8000 g / (m²·24h), and the waterproof and breathable performance degradation rate is ≤8% after 20 washes.

6. A film-forming process for applying the water-based PU waterproof and breathable membrane to a waterproof jacket as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1, Raw material pretreatment: Select qualified anionic aliphatic waterborne PU resin, filter it under pressure using a 100-200 mesh filter to remove impurities and gel particles inside the resin, and let it stand at room temperature (25℃) for 10-20 minutes to eliminate micro bubbles generated during raw material storage. Step S2, Precise proportioning and mixing: Add deionized water, wetting and leveling agent, flexibility and toughening agent, moisture-permeable agent and waterproof agent in sequence according to the formula mass percentage. After low-speed pre-stirring, add water-based PU resin and prepare a uniform liquid using a segmented gradient stirring process. Step S3, Vacuum defoaming and settling: Put the mixed liquid into a vacuum defoaming tank and defoam for 5 to 10 minutes under a vacuum of -0.06 to -0.09 MPa. Then let it stand at room temperature in a sealed environment for 15 to 25 minutes to completely eliminate microbubbles in the system. Step S4, Precision coating and film formation: Using slit coating or roller coating processes, the defoamed liquid is evenly coated on the surface of the release substrate, and the wet film thickness is controlled to be 0.08-0.15mm. Step S5, Multi-stage gradient drying and curing: The coated film is sent into a thermal oil furnace for heating and drying. A three-stage gradient heating and drying process is adopted to complete low-temperature pre-drying, medium-temperature cross-linking and curing, and high-temperature shaping treatment in sequence. The waste gas generated during the drying process is treated and discharged by RTO. Step S6, Constant Temperature Cooling and Shaping: After drying and curing, use uniform air cooling to cool, control the cooling rate to 3-5℃ / min, and cool to room temperature of 25℃, then keep it at a constant temperature for 20-30 minutes to set. Step S7, winding and post-processing: After the shaping is completed, the film is wound up smoothly, and the winding tension is kept constant to avoid wrinkles and stretching deformation, so as to obtain the finished water-based PU waterproof and breathable membrane.

7. The film-forming process for a water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 6, characterized in that, The S2 segmented gradient stirring process is as follows: first, stir at a low speed of 200-300 r / min for 8-12 min to achieve initial dispersion of the additives; then, stir at a medium speed of 500-600 r / min for 20-30 min to achieve uniform compatibility of each component; finally, stir at a low speed of 350-400 r / min for 5-8 min to eliminate eddy bubbles generated by high-speed stirring, ensuring that the liquid system is uniform, stable, and free from stratification and agglomeration.

8. The film-forming process for a water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 6, characterized in that, The specific parameters of the S5 multi-stage gradient drying and curing process are as follows: the first stage is a low-temperature pre-drying temperature of 55-65℃ and a drying time of 6-10 min, which slowly removes free water from the surface of the liquid and avoids rapid skinning on the surface; the second stage is a medium-temperature curing temperature of 85-95℃ and a drying time of 10-15 min, which promotes the cross-linking reaction of resin molecular chains and forms a stable micro-network structure; the third stage is a high-temperature setting temperature of 105-115℃ and a drying time of 4-6 min, which completes the densification and setting of the film and improves the mechanical properties and water resistance of the film.

9. The film-forming process for a water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 6, characterized in that, The environmental parameters for the coating process are controlled as follows: ambient temperature 22-28℃, ambient humidity 40%-60%, and dust-free class 10,000 to avoid dust adhering to the film surface and causing performance defects, and to ensure film consistency and yield.

10. The film-forming process for a water-based PU waterproof and breathable membrane for a waterproof jacket according to claim 6, characterized in that, The film-forming process uses pure water as the dispersion medium throughout, with no added organic solvents or organic solvent volatilization. The VOC emissions during production are extremely low, and the production equipment does not require explosion-proof modifications. The production system is non-flammable and non-explosive, and there is no release of toxic or irritating gases. Through precise formulation and synergistic coupling of multi-stage gradient film-forming processes, the technical defects of traditional water-based PU films, such as uneven film formation, numerous pinholes and bubbles, weak adhesion, poor water washability, and low mass production stability, are solved, enabling continuous and large-scale industrial mass production with a yield rate of ≥98%.

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