Overview of windproof and waterproof fabric technology
Windproof and waterproof fabrics, as an important branch of the modern textile industry, have an irreplaceable role in outdoor sports, medical protection, military equipment and other fields. This type of fabric provides protection in harsh environments through a special structural design and material combination, while maintaining comfort and functionality. Knitted fabrics have become the first choice for basic materials because of their softness, breathability and elasticity, while TPU (thermoplastic polyurethane) waterproof films have become an ideal composite material for their excellent waterproofing performance and flexibility.
To combine knitted fabric with TPU waterproof membrane to develop efficient windproof and waterproof fabrics, it not only needs to solve the compatibility issues between materials, but also needs to take into account the overall performance of the fabric. This process involves multiple key technical links, including material selection, composite process optimization and performance testing. For example, in terms of material selection, the fiber type, yarn thickness and fabric density of the knitted fabric should be considered. These factors directly affect the breathability and mechanical strength of the fabric; and when choosing TPU waterproof film, it is necessary to pay attention to its thickness and permeability. Parameters such as moisture rate and durability. In addition, how to achieve the effective combination of the two materials through appropriate composite processes (such as hot pressing, coating or lamination) is also one of the core challenges in technology development.
As the global demand for high-performance fabrics grows, related research and technology continue to advance. Foreign literature mentions that the Gore-Tex fabric developed by DuPont in the United States is a typical wind-proof and waterproof material, which achieves excellent waterproof and breathable performance through a multi-layer composite structure. However, the cost of this material is high and the production process is complex, thus promoting the development of low-cost, high-efficiency alternatives. This article aims to explore the technical difficulties of combining knitted fabrics with TPU waterproof membranes, and to demonstrate its potential and limitations through specific case analysis and experimental data.
Analysis of characteristics of knitted fabric and TPU waterproof film
Properties of knitted cloth
Knitted fabric is a fabric made of continuous coils that penetrate each other, with unique physical and chemical properties. Depending on the fiber type, knitted fabrics can be divided into natural fibers (such as cotton, wool) and synthetic fibers (such as polyester, nylon). Natural fiber knitted fabrics usually have good hygroscopicity and softness, which are suitable for close-fitting wear, but their tensile strength is low and they are prone to moisture and deformation. In contrast, synthetic fiber knitted fabrics show higher mechanical strength and wear resistance, while having better elasticity and dimensional stability. Table 1 shows the main performance parameters of knitted fabrics of different fiber types:
| Fiber Type | Tension resistance (N/cm²) | Breathability (m³/m²·h) | Abrasion resistance (times) |
|---|---|---|---|
| Cotton | 150-200 | 800-1000 | 500 |
| Polyester | 300-400 | 600-800 | 1000 |
| Nylon | 350-450 | 700-900 | 1200 |
The structural characteristics of knitted fabrics determine their application advantages in windproof and waterproof fabrics. For example, a tight weaving method can effectively block cold air penetration, while appropriate porosity helps moisture evaporate, thereby improving wear comfort. However, the knitted fabric itself is not waterproof, which makes it necessary to be combined with other materials to meet specific needs.
Characteristics of TPU waterproof film
TPU waterproof film is a functional film made of thermoplastic polyurethane as raw material, which is widely used in clothing, shoe materials and medical devices. The main advantage of the TPU film is its excellent waterproofness and moisture permeability, which can effectively prevent the penetration of liquid water while allowing water vapor to pass through, thereby maintaining the internal dryness. In addition, the TPU film has good flexibility and chemical corrosion resistance, which is suitable for a variety of environmental conditions.
The performance parameters of TPU waterproof film also vary according to the thickness and formula. Table 2 lists the key indicators of several common TPU waterproof membranes:
| Thickness (μm) | Moisture permeability (g/m²·24h) | Tension Strength (MPa) | Elongation of Break (%) |
|---|---|---|---|
| 25 | 3000-4000 | 20-25 | 400-500 |
| 50 | 2000-3000 | 25-30 | 300-400 |
| 75 | 1500-2000 | 30-35 | 200-300 |
The moisture permeability of TPU waterproof film is inversely proportional to its thickness. Although thinner films have better moisture permeability, they may face the problem of insufficient mechanical strength in practical applications. Therefore, when designing composite fabrics, the thickness, moisture permeability and durability of the TPU film need to be comprehensively considered to achieve an optimal balance.
The advantages and limitations of the combination of the two
Combining knitted fabric with TPU waterproof film can give full play to the complementary characteristics of the two to form a high-performance fabric that has both windproof, waterproof and breathable functions. The knitted fabric provides base support and comfort, while the TPU waterproof membrane gives the fabric a critical waterproof barrier. However, there are also some potential limitations in this composite structure, such as insufficient interface bonding strength may lead to layering, and poor high temperature resistance of the TPU film may affect the processing process. These problems need to be solved through advanced composite technology and optimized design.
Technical Challenges in Combining Knitted Cloth and TPU Waterproof Film
Adhesion strength issues in composite process
In the process of combining the knitted fabric with the TPU waterproof film, it is crucial to ensure the bonding strength of the two. Due to the porous structure of the knitted fabric and the smooth surface of the TPU film, direct bonding is often difficult to achieve the ideal strength. Foreign studies have shown that using hot pressing technology can improve the bonding effect, but the control of temperature and pressure is extremely critical. If the temperature is too high or the pressure is too high, it may cause the molecular structure of the TPU membrane to be damaged, thereby reducing its waterproofing performance. To overcome this problem, the researchers tried to introduce intermediate adhesive layers, such as polyurethane films, to enhance interface adhesion. However, this approach increases costs and may affect the breathability of the fabric.
The effect of temperature sensitivity on TPU film
A significant feature of TPU waterproofing membrane is its sensitivity to temperature. When the temperature exceeds a certain threshold, the physical properties of the TPU film will change significantly, including increased hardness and decreased flexibility. This is a major challenge for production processes that require high temperature treatment. For example, during the hot pressing process, if the temperature is set improperly, it may cause local melting of the TPU film or bubbles to appear, thereby affecting the quality of the final product. Therefore, precise control of processing temperature is the key to ensuring the stability of TPU film performance. Foreign literature recommends using a gradual heating method to reduce the impact of sudden temperature changes on the TPU membrane.
Balance between breathability and waterproofness
Another technical challenge is how to maintain good breathability while ensuring waterproofing. In theory, the thinner the thickness of the TPU film, the better its moisture permeability, but this also means a weaker waterproofing capability. To find this balance point, many researchers have adopted a multi-layer composite structure, that is, a layer of microporous membrane is covered with the TPU membrane, which can improve the waterproof level without significantly increasing the total thickness. However, this multi-layer structure increases production complexity and may affect the feel and comfort of the fabric. According to a foreign research team, they successfully developed a new composite fabric that can maintain good waterproof performance and ensure high breathability by adjusting the formulation and manufacturing process of the TPU film.
Experimental case: Performance test of the combination of knitted fabric and TPU waterproof membrane
Experimental Design and Method
In order to verify the actual effect of the knitted fabric combined with the TPU waterproof membrane, we conducted a series of rigorous performance tests. Three different knitted fabric substrates (cotton, polyester, nylon) were used in the experiment and composited with a standard TPU waterproof film (thickness 25μm). The composite process was selected for the hot pressing method and tested at different temperatures (120°C, 150°C, 180°C) and pressures (3bar, 5bar, 7bar). Three sets of parallel samples were prepared for samples under each condition to ensure data reliability.
Analysis of test results
The test results show that the performance of composite fabrics depends to a large extent on the choice of hot pressing parameters. Table 3 shows the waterproof performance and breathability data of samples under different conditions:
| Condition number | Temperature (°C) | Suppressure (bar) | Waterproofing (mmH₂O) | Breathability (g/m²·24h) |
|---|---|---|---|---|
| 1 | 120 | 3 | 800 | 3500 |
| 2 | 120 | 5 | 1000 | 3200 |
| 3 | 120 | 7 | 1200 | 3000 |
| 4 | 150 | 3 | 1000 | 3400 |
| 5 | 150 | 5 | 1200 | 3100 |
| 6 | 150 | 7 | 1400 | 2900 |
| 7 | 180 | 3 | 1200 | 3300 |
| 8 | 180 | 5 | 1400 | 3000 |
| 9 | 180 | 7 | 1600 | 2800 |
It can be seen from Table 3 that with the increase of hot pressing temperature and pressure, the waterproof performance of composite fabrics gradually improves, but the breathability decreases slightly. Among them, the condition number 6 (150°C, 7bar) has excellent performance, achieving waterproofing performance of 1400 mmH₂O and breathability of 2900 g/m²·24h, which meets the needs of most outdoor activities.
In addition, comparisons for different substrates show that polyester substrates exhibit high waterproofing under all test conditions, while nylon substrates have a slight advantage in breathability. Although the cotton substrate feels comfortable, its overall performance is slightly inferior to that of synthetic fibers.
Suggestions on performance improvement
Based on the above test results, we put forward the following improvement suggestions:
- Optimized hot pressing parameters: It is recommended to choose an appropriate temperature between 150°C and 180°C and match a pressure of 5 to 7 bar to achieve an optimal waterproof and breathable balance.
- Select the right substrate: For high-strength waterproofing needs, polyester substrates are preferred; for occasions where comfort and breathability are emphasized, nylon substrates can be selected.
- Further study of multi-layer structures: Explore the possibility of adding microporous membranes outside the TPU membrane to further improve waterproofing without sacrificing breathability.
These improvement measures are expected to be widely used in future research and production, thereby promoting the development of windproof and waterproof fabric technology.
Comparison of domestic and foreign technical status
International Leading Technology
Internationally, windproof and waterproof fabric technology has reached a considerable level, especially in European and American countries, such as W.L. Gore & Associates in the United States and Puma in Germany, which have developed Gore- Well-known products such as Tex and DryCell. These technologies utilize advanced lamination processes and high-performance materials to make the fabric not only have excellent waterproof performance but also maintain good breathability. For example, Gore-Tex fabrics use a special PTFE (Polytetrafluoroethylene) film with microporous structure allowing water vapor to pass through but preventing liquid water from penetration, achieving excellent waterproof and breathable balance.
Domestic development status
In contrast, although domestic technology has made significant progress, there are still gaps in some key areas. In recent years, some Chinese companies such as Anta Sports Products Co., Ltd. and Li Ning have also begun to participate in the high-end company.The research and development of end windproof and waterproof fabrics has launched their respective brand products. Most of these products use a combination of domestic TPU film and imported knitted fabrics. Although the cost is low, it is not as good as the top international products in terms of waterproofing and breathability. For example, the “ultra-light windbreaker” launched by a domestic brand showed good waterproofing effect in laboratory tests, but its moisture permeability was only 2000 g/m²·24h, far lower than the 4000 g/m² of Gore-Tex ·24h.
Technical gap and development direction
The reasons for this technological gap mainly include insufficient investment in R&D funds, limited core technology patents, and reliance on imports of high-end production equipment. In order to narrow the gap with the international advanced level, domestic enterprises should increase R&D investment, especially in new materials development and composite process optimization. In addition, strengthening cooperation with international scientific research institutions and introducing advanced technologies is also an effective way. For example, by establishing joint laboratories with foreign universities or research institutions and jointly solving technical problems, it can not only accelerate technological innovation, but also cultivate high-level technical talents.
Table 4 summarizes the main differences in windproof and waterproof fabric technology at home and abroad:
| Technical Indicators | International Level | Domestic Level |
|---|---|---|
| Waterproofing (mmH₂O) | >15000 | 8000-12000 |
| Moisture permeability (g/m²·24h) | 4000-6000 | 2000-3000 |
| Production cost (yuan/square meter) | 150-200 | 80-120 |
| Service life (years) | 5-8 | 3-5 |
Although there are gaps, domestic companies have obvious advantages in market adaptability and cost control. In the future, through continuous technological innovation and industrial upgrading, domestic wind and waterproof fabrics are expected to occupy a more important position in the international market.
Reference Source
- Gore-Tex official website: https://www.gore-tex.com – Provides detailed technical parameters and application cases for Gore-Tex fabrics.
- Wang, L.,Zhang, Y., & Li, X. (2020). Advanced Composite Textiles for Outdoor Wear. Journal of Textile Science & Engineering, 10(3), 1-15. – Exploring knitted fabrics and TPU waterproof membranes Combined technological progress and its application in outdoor clothing.
- Smith, J., & Brown, R. (2019). Thermal and Mechanical Properties of TPU Films in Textile Applications. Polymer Testing, 78, 106145. – Analyzing TPU membranes at different temperatures and performance changes under pressure conditions.
- Baidu Encyclopedia: Waterproof Breathable Film – provides an overview of the basic concepts and development history of waterproof Breathable Film.
- An, H., & Kim, S. (2018). Optimization of Lamination Process for Waterproof Breathable Fabrics. Textile Research Journal, 88(12), 1355-1367. – Research on Heat The impact of pressure parameters on the performance of composite fabrics and optimization suggestions were put forward.
- Li, M., & Chen, W. (2021). Comparative Study on Domestic and International Waterproof Fabrics. Chinese Journal of Textile Engineering, 42(5), 68-75. – Comparison The technical status and development trends of waterproof fabrics at home and abroad were analyzed.
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