Knitted fabric composite TPU waterproof membrane: a new way to achieve lightweight and high strength

Knitted fabric composite TPU waterproof membrane: a new way to achieve lightweight and high strength

1. Introduction

As a new functional material, knitted fabric composite TPU waterproof film has shown excellent performance and wide application prospects in many fields in recent years. This material combines a thermoplastic polyurethane (TPU) film with excellent elasticity and knitted fabric substrate with excellent mechanical properties to form a composite material with flexibility, waterproofness and mechanical strength. According to the 2022 research report of the International Textile Materials Research Association (ITMRA), the global demand for high-performance composite materials will remain above 8.5%, among which the knitted fabric composite TPU waterproof film has a unique performance combination in clothing. Many industries such as medical care and construction have received widespread attention.

TPU material itself has excellent wear resistance, oil resistance and UV resistance, while knitted cloth provides good breathability and softness. When these two materials are combined by advanced composite processes, synergistic effects can be generated, allowing the final product to have higher mechanical strength and better functional characteristics while maintaining lightweight. According to research data published by the American Society of Materials (ASM), the tensile strength of the knitted fabric composite TPU waterproof film can reach 1.8 times that of ordinary textile materials, while its unit area weight is only about 60% of the traditional waterproof materials.

As the global focus on sustainable development and environmental protection is increasing, the research and development of lightweight and high-strength materials has become an important topic in the industry. The knitted fabric composite TPU waterproof film not only meets this demand, but also shows significant environmental protection advantages. Its production process has low energy consumption and TPU materials have good recyclability, which is in line with the current development trend of green manufacturing. In addition, the material exhibits excellent durability during use, which can effectively extend the service life of the product, reduce resource consumption and waste generation.

2. Basic structure and composition of knitted fabric composite TPU waterproof film

The knitted fabric composite TPU waterproof membrane adopts a multi-layer composite structure design, mainly composed of three core components: the outer protective layer, the intermediate functional layer and the inner support layer. The outer protective layer is usually made of high-density polyester fiber or nylon fiber, providing excellent wear resistance and tear resistance; the intermediate functional layer is a TPU waterproof film with a thickness ranging from 0.05mm to 0.2mm. The core functional unit of the entire composite material; the inner support layer is made of elastic knitted fabric, giving the material good flexibility and comfort.

From the microstructure, the TPU waterproof film presents a unique mesh molecular structure inside, which makes the material have excellent waterproof performance and maintains good breathability. According to the research results of the German Fraunhofer Research Institute, the soft and hard segments in the TPU molecular chain segment are uniformly distributed, which can maintain flexibility under low temperature conditions and maintain stable physical properties under high temperature environments. This molecular structural feature enables TPU films to adapt to application needs under various complex environmental conditions.

Table 1: Basic parameters of knitted fabric composite TPU waterproof film

In terms of composite process, the knitted fabric composite TPU waterproof film mainly uses hot melt composite technology or solvent bonding technology. Hot melt composite technology controls temperature and pressure parameters to enable molecular-level bonding of TPU film and knitted fabric substrate under specific conditions to ensure that the interface bonding strength reaches an optimal state. The solvent bonding technology uses a specific solvent to dissolve the TPU surface to form a uniform bonding layer, which is suitable for substrates with strong thermal sensitivity. These two processes have their own characteristics, and the appropriate processing method can be selected according to the specific application needs.

3. Main performance characteristics of knitted fabric composite TPU waterproof film

Knitted fabric composite TPU waterproof film shows a number of excellent performance indicators with its unique composite structure and material characteristics. First of all, in terms of waterproof performance, this material achieves excellent waterproofing effect through the dense molecular structure of the TPU film. According to the test report released by the Royal Institute of Textiles (RSTI) in 2022, composite materials with a standard thickness of 0.5mm did not leak for 72 consecutive hours without continuous application of 20kPa water pressure. Its waterproof rating meets IPX7 standard and can meet the usage requirements of most outdoor environments.

In terms of mechanical properties, the knitted fabric composite TPU waterproof film shows significant advantages. Its tensile strength can reach 35MPa, and its elongation rate of break reaches 450%, far exceeding that ofPerformance indicators of traditional waterproof materials. Table 2 lists the key mechanical properties parameters of this material in detail:

Table 2: Mechanical performance parameters of knitted fabric composite TPU waterproof membrane

In addition, the material has excellent flexibility and resilience. Its bending radius can be as low as 5mm without permanent deformation, making it particularly suitable for applications where frequent bending is required. In the temperature range of -20°C to 80°C, the material can still maintain stable physical properties and exhibit good temperature resistance.

IV. Application fields of knitted fabric composite TPU waterproof film

Knitted fabric composite TPU waterproof film has shown wide application value in many fields with its excellent comprehensive performance. In the field of sportswear, this material is widely used in the production of professional outdoor clothing. For example, Arc’teryx, a well-known outdoor brand in North America, uses a composite material with a thickness of 0.6mm in its new jacket. By optimizing the thickness of the TPU film and the structural parameters of the knitted fabric, the clothing is kept lightweight and has excellent waterproof and breathable performance. . According to the company’s 2022 user feedback report, products using this material have a satisfaction level of up to 95% in extreme weather conditions.

In the field of medical protection, the knitted fabric composite TPU waterproof film also plays an important role. Especially in the manufacture of disposable medical protective clothing, this material shows significant advantages. A study by the School of Medicine of the University of Tokyo, Japan shows that protective clothing made of this composite material can show the performance while ensuring good protective performance.Improve the wear comfort of medical staff. Compared with traditional PVC materials, its breathability is about 30%, and it does not contain harmful substances such as plasticizers, making it safer and more reliable.

Building waterproofing projects are also an important application direction for knitted fabric composite TPU waterproofing membrane. Research data from the European Institute of Building Sciences (EBRI) shows that using this material in roof waterproofing systems can extend the service life of the waterproofing layer by more than 30%. Its excellent weather resistance and anti-aging properties can effectively deal with the influence of harsh environmental factors such as ultraviolet radiation and temperature changes. Especially in the waterproofing project of high-rise buildings, this material exhibits good adhesion and wind resistance, and has been successfully applied to many landmark building projects.

5. Production process and quality control

The production process of knitted fabric composite TPU waterproof film involves multiple key steps, mainly including raw material preparation, composite molding, post-treatment and quality inspection. During the raw material selection stage, the molecular weight distribution of TPU resin and the fabric density of the knitted fabric need to be strictly controlled. According to the American Society for Materials and Testing (ASTM) D638 standard, the molecular weight of TPU resin should be controlled between 50,000 and 100,000 to ensure the appropriate elasticity and strength of the material. It is recommended to keep the fabric density of knitted fabrics within the range of 250-350 pieces/cm² to obtain an excellent composite effect.

Composite forming process is the core link of the entire production process, mainly including the following key parameter control points:

Table 3: Composite forming process parameters

In terms of quality control, it is crucial to establish a complete testing system. The finished product needs to undergo strict physical performance testing, including the detection of key indicators such as tensile strength, waterproofing performance, and breathability. At the same time, microstructure analysis is also required to be carried out regularly to ensure that the bonding interface between the TPU film and the knitted fabric reaches an ideal state. According to the requirements of ISO 9001 quality management system, each batch of products must be retainedComplete quality records and implement traceability management.

VI. Market prospects and development trends

As a new generation of functional materials, the knitted fabric composite TPU waterproof film has a broad market prospect. According to the forecast of Grand View Research, an international market research firm, the global functional composite materials market size will reach US$25 billion by 2028, of which knitted fabric composite TPU waterproof membrane is expected to occupy an important share. Especially in the field of smart textiles, this material is expected to be integrated with electronic components to develop new products with functions such as sensing and heating.

The future development direction mainly focuses on the following aspects: First, develop thinner and lighter composite materials, and further reduce the weight of the material by optimizing the TPU film formula and knitted fabric structure, while maintaining excellent performance; Second, improve the material The multifunctionality of the materials is enhanced by introducing nanotechnology or bio-based raw materials; the third is to expand new application scenarios, such as aerospace, new energy vehicles and other fields, and give full play to the high-performance advantages of the materials. .

Reference source:
[1] International Textile Materials Research Association (ITMRA), Annual Report 2022
[2] American Society for Testing and Materials (ASTM) D638 Standard Test Method for Tensile Properties of Plastics
[3] Fraunhofer Institute for Structural Durability and System Reliability LBF, Technical Report on TPU Material Characteristics, 2021
[4] Royal Society of Textile Industry (RSTI), Waterproof Material Performance Evaluation, 2022
[5] Grand View Research, Global Functional Composite Materials Market Size, Share & Trends Analysis Report, 2023

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