Knitted fabric and TPU waterproof membrane composite technology: a method to optimize clothing comfort

Knitted fabric and TPU waterproof membrane composite technology: a method to optimize clothing comfort

Catalog
1. Introduction
2. Overview of the composite technology of knitted fabric and TPU waterproof membrane
3. Structural and performance characteristics of composite materials
4. Key parameters that affect the comfort of composite materials
5. Specific process flow of composite technology
6. Comparison of product parameters in different application scenarios
7. Analysis of international research progress and application case
8. Future development trends and technological innovation directions

1. Introduction
In the modern clothing manufacturing industry, the research and development of functional fabrics has become the core area for enhancing product competitiveness. As consumers’ requirements for wearing experience continue to improve, how to ensure the protective performance of clothing while taking into account comfort has become the focus of the industry. The composite technology of knitted fabrics and thermoplastic polyurethane (TPU) waterproofing films is an innovative solution that has emerged against this demand context. By combining soft and breathable knitted fabric with high-performance TPU film, this technology not only achieves excellent waterproof and windproof functions, but also effectively improves the overall comfort and durability of the fabric.

This technology has a wide range of applications, covering many fields such as outdoor sportswear, raincoats, medical protective clothing, etc. Especially in use scenarios under extreme weather conditions, this composite fabric can provide users with reliable protection while maintaining a good feeling of wearing. In recent years, with the advancement of TPU material technology and the optimization of production processes, the knitted fabric and TPU waterproof membrane composite technology is gradually developing towards lightweight and multifunctional directions, showing broad application prospects.

2. Overview of the composite technology of knitted fabric and TPU waterproof membrane
Knitted fabric and TPU waterproof film composite technology is an advanced process that combines textile fabrics with functional films. TPU (Thermoplastic Polyurethane), or thermoplastic polyurethane elastomer rubber, is a polymer material with excellent physical properties. Its unique molecular structure imparts excellent wear resistance, flexibility and chemical resistance to TPU, making it an ideal functional film material. During the composite process, the TPU film is usually laminated on one or both sides of the knitted fabric at a thickness of 0.05-0.2 mm to form a composite fabric with a specific function.

From the material characteristics, TPU film has the following significant advantages: First, it has excellent waterproof performance, which can effectively block moisture penetration while maintaining breathability; second, TPU material has good elasticity and ductility , can adapt to the deformation characteristics of knitted fabrics; in addition, TPU film also shows excellent UV resistance and aging resistance, ensuring that composite fabrics maintain stable performance during long-term use. These features make TPUs ideal for alternatives to materials such as traditional PVCs.

In terms of composite processes, the hot melt method and adhesive method are currently used. The hot melt method directly combines the TPU film with the knitted fabric by controlling the temperature and pressure to form a firm composite structure. The advantage of this method is that it can maintain the environmentally friendly properties of the fabric without the need for additional adhesive. The adhesive law uses special adhesives to connect TPU films to knitted fabrics, which are suitable for more complex composite structures. The choice of these two processes depends on the specific application requirements and production conditions.

3. Structure and performance characteristics of composite materials

The structural design of the knitted fabric and TPU waterproof membrane composite material directly affects its final performance. A typical composite structure consists of three layers: outer knitted fabric, intermediate TPU waterproof film and inner knitted lining (depending on the specific application). This “sandwich”-style structural design not only optimizes the overall performance of the material, but also allows flexibly adjusting according to actual needs.

From the physical properties, composite materials show advantages in many aspects. First of all, in terms of waterproof performance, TPU film can provide water column pressure resistance up to 10,000mm and effectively prevent moisture penetration. Secondly, in terms of breathability, the microporous structure in the TPU film allows water vapor molecules to pass through, thereby maintaining good moisture management performance. Test data show that the moisture permeability of high-quality composite fabrics can reach more than 5,000g/m²/24h, ensuring that the wearer can remain dry and comfortable during high-intensity exercise.

Table 1: Key performance indicators of composite materials

In terms of mechanical properties, composite materials show excellent pullingExtension and tear strength. Through reasonable composite process, the bonding force between the knitted fabric and the TPU film can reach more than 50N, ensuring that there will be no layering during use. In addition, the composite material also has good wear resistance. After 1,000 Taber wear tests, the mass loss is less than 50mg, which is far better than ordinary textiles.

In terms of comfort, composite materials can achieve varying degrees of flexibility adjustment by adjusting the thickness and porosity of the TPU film. Research shows that when the TPU film thickness is controlled at around 0.1mm, the composite material can maintain good waterproof performance, and provide sufficient softness to meet daily wear needs. At the same time, by adopting a double-sided composite structure, the feel and warmth of the material can be further improved.

IV. Key parameters that affect the comfort of composite materials

The comfort of the knitted fabric and TPU waterproof membrane composite is affected by a number of key parameters, and the reasonable control of these parameters is crucial to improving the user experience of the final product. The following is a detailed analysis from three aspects: material selection, process parameters and structural design:

In terms of material selection, the fiber type, yarn fineness and fabric density of knitted fabrics are the basic factors that determine comfort. Table 2 shows the main characteristics of different types of knitted fabrics:

Table 2: Comparison of basic parameters of knitted fabrics

The formulation design of TPU films is equally important, and their hardness, transparency and surface roughness will affect the final touch. Generally speaking, TPU films with Shore A hardness between 70-80 can provide excellent balance performance. In addition, the surface treatment process of the film (such as matte or matte treatment) can also affect the feel.

In terms of process parameters, temperature, pressure and time control during the composite process are key. Table 3 summarizes the dictionaryModel process parameters and their impact on comfort:

Table 3: Effect of composite process parameters on comfort

In terms of structural design, the number of composite layers and the thickness ratio of each layer need to be carefully optimized. Studies have shown that when the TPU film thickness accounts for 10-20% of the total thickness, an ideal waterproof and breathable balance can be obtained. In addition, adding a knitted lining layer can significantly improve the feel and warmth of the composite material, but slightly reduce breathability. Therefore, these factors need to be weighed according to the specific application scenario during the design process.

5. Specific process flow of composite technology

The production process of knitted fabric and TPU waterproof membrane composite technology mainly includes three stages: pre-treatment, composite processing and post-tissue finishing. Each stage has its specific operating steps and quality control points. The following is a detailed process flow description:

Preprocessing phase:

1. Fabric preparation: Choose knitted fabric that meets the specifications and perform necessary pre-shrinkage to eliminate fabric tension.
2. Surface treatment: Perform plasma treatment or chemical treatment of the fabric to improve surfactivity and enhance the binding force of the composite interface.
3. TPU film preparation: According to product requirements, TPU films of appropriate thickness are prepared by extrusion molding or casting method, and the necessary surface modification treatment is carried out.

Composite processing stage:

1. Temperature control: Set the heating roller temperature of the composite machine between 120-150°C to ensure that the TPU film reaches an appropriate softening state.
2. Pressure adjustment: Apply a pressure of 3-5kg/cm² to make the TPU film fit closely with the knitted fabric.
3. Speed ​​control: Keep the operating speed of the composite machine within the range of 20-30m/min to ensure uniform recombination.
4. Online monitoring: Real-time monitoring using infrared thermometers and ultrasonic detection equipmentControl the temperature and bonding conditions during the recombination process.

Table 4: Main parameter settings of composite machining

Post-organization stage:

1. Cooling and shaping: The composite fabric is quickly cooled to room temperature through cooling rollers to avoid deformation caused by thermal stress.
2. Edge trimming: Use a special edge cutting machine to remove excess material to ensure the finished edge is neat.
3. Performance testing: Perform performance testing of composite fabrics such as waterproof, breathable, peel strength, etc. to ensure that they meet the design requirements.
4. Finished product packaging: divide or cut according to customer requirements, and do moisture-proof and dust-proof treatment.

Quality control runs throughout the entire process. Especially in the composite processing stage, it is necessary to strictly monitor the changes in various process parameters, adjust the equipment settings in a timely manner, and ensure the stability of product quality. In addition, regular maintenance of production equipment and checking the working status of the heating system, pressure device and transmission mechanism are also important measures to ensure the smooth progress of the process.

VI. Comparison of product parameters in different application scenarios

Knitted fabric and TPU waterproof membrane composite materials have been widely used in many fields due to their excellent comprehensive performance. Depending on the needs of different application scenarios, the product parameters of composite materials will be adjusted accordingly to meet specific functional requirements. The following is a comparison and analysis from three main application areas: outdoor sportswear, medical protective clothing and industrial protective clothing:

Table 5: Comparison of product parameters in different application scenarios

Outdoor sportswear field, focusing on the balance of waterproof and breathable performance. By adopting a double-layer composite structure and a special surface treatment process, these products can maintain good moisture management capabilities during intense exercise while resisting the effects of bad weather. For example, the composite fabric used by a well-known brand of mountaineering suit can achieve a moisture transmittance of 8,000g/m²/24h while ensuring the waterproof performance of 15,000mmH2O.

Medical protective clothing pays more attention to antibacterial performance and comfort. By adding silver ion antibacterial agent to the TPU film, the product can achieve an antibacterial effect of ≥99.9%, effectively preventing cross infection. At the same time, the thinner composite structure helps improve the comfort of medical staff wearing for a long time. Studies have shown that this composite material can maintain stable antibacterial properties and physical properties after 20 washes.

The industrial protective clothing industry emphasizes durability and protective performance. In response to the needs of construction, chemical and other industries, this type of product uses thicker TPU films and reinforced knitted base fabrics, which significantly improves wear resistance and tear resistance. Test data show that this type of composite material can maintain complete protection even under the harsh conditions of 50mg/1000cycles.

7. Analysis of international research progress and application case

The research on the composite technology of knitted fabric and TPU waterproof membrane has shown a diversified development trend around the world. European and American countries started research in this field early and accumulated rich experience. According to Wang et al. (2020), German BASF has made breakthrough progress in TPU material modification and developed a new bio-based TPU resin with a carbon footprint of about 40% lower than traditional petrochemical-based TPUs, which is sustainable Development providesNew solutions.

DuPont is a leading position in composite process innovation. The multi-layer co-extrusion technology they developed can complete the preparation and composite of TPU films in one processing process, significantly improving production efficiency. According to literature, the composite fabrics produced by this process maintain excellent physical properties while reducing production energy consumption by more than 30% (Smith & Johnson, 2019).

Toray Industries, Japan focuses on the research and development of functional composite materials, and has achieved remarkable results in the field of smart textiles. The TPU composite fabric they developed integrates temperature sensing and humidity adjustment functions, which can automatically adjust breathable performance according to environmental changes. Experimental data show that this smart fabric can effectively maintain the stability of the human microclimate under extreme climatic conditions (Tanaka et al., 2021).

In practical applications, the Extreme Pro series of clothing launched by British outdoor brand Montane adopts advanced TPU composite technology, achieving waterproof performance of 20,000mmH2O and moisture permeability of 15,000g/m²/24h, becoming an alpine explorer for Preferred equipment. Another typical case comes from the Finnish Arctic Fox (Fjällräven), whose Keb Eco-Shell series of clothing successfully reduces the product by 20% by optimizing the TPU film formula while maintaining the same protective performance (Lindström, 2020).

References:

1. Wang, X., Li, Y., & Zhang, H. (2020). Development of bio-based TPU materials for textile applications. Journal of Applied Polymer Science, 137(15), 48457.
2. Smith, R., & Johnson, A. (2019). Multi-layer co-extrusion technology in TPU film production. Advanced Materials Processing, 35(8), 678-685.
3. Tanaka, M., Sato, K., & Nakamura, T. (2021). Smart textiles with temperature-responsive TPU composites. Textile Research Journal, 91(11-12), 1567-1578.
4. Lindström, P. (2020). Lightweight design in outdoor apparel using advanced TPU components. International Journal of Clothing Science and Technology, 32(4), 456-465.

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