Overview of the composite process of knitted fabric and TPU waterproof membrane
The composite process of knitted fabric and TPU (thermoplastic polyurethane) waterproof film is an advanced manufacturing technology that combines functional films with textile materials. Through a specific processing process, this composite material perfectly combines a TPU film with excellent waterproof performance with a soft and comfortable knitted fabric, forming a new composite material that has both breathability and waterproofness. According to authoritative foreign literature records, this technology originated in Europe and the United States in the 1970s and was first applied to the field of high-end outdoor equipment. With the continuous advancement of technology, it has now been widely used in many industrial fields.
In the composite process, the TPU film, as an important functional layer, is usually controlled between 10-30μm in thickness, which can provide excellent waterproof performance while maintaining good flexibility and durability. As a base material, knitted fabric is made of high-performance fibers such as polyester and nylon, which has excellent comfort and durability. These two materials are organically combined through processes such as hot pressing composite, adhesive composite or vacuum bonding to form composite materials with specific functional characteristics.
The core advantage of this composite material lies in its unique sandwich structure, that is, the outer layer is a wear-resistant protective layer, the middle is a TPU waterproof and breathable membrane, and the inner layer is a comfortable and skin-friendly knitted fabric. This structural design not only ensures the overall performance of the material, but also gives the product multiple functional characteristics. According to a research report published by Wiley, an internationally renowned research institution, the waterproofing level of this composite material can reach more than 5000mm and the moisture permeability can reach 5000g/m²/24h, showing excellent functional balance.
In industrial applications, this composite material is highly favored for its outstanding performance. For example, in the medical field, it is used to make protective clothing, which can effectively block liquid penetration and maintain good breathability; in the construction industry, it is used as a waterproof and thermal insulation material; in the automobile manufacturing industry, it can also be used as a waterproof and thermal insulation material; Used as interior material. These diverse applications fully demonstrate the strong adaptability and market potential of knitted fabrics and TPU waterproof membrane composites.
Composite process classification and characteristics analysis
The composite process of knitted fabric and TPU waterproof film can be mainly divided into three types: hot press composite, adhesive composite and vacuum bonding. Each process has its own unique characteristics and applicable scenarios, which will be introduced in detail below.
Hot press composite process
Hot pressing composite is one of the common composite methods. Its basic principle is to directly fuse the TPU film with the knitted fabric under specific temperature and pressure conditions. According to the research data of “Journal of Applied Polymer Science”, the best process parameters for hot pressing composite are usually: temperature range 120-150°C, pressure 0.5-2MPa, time 30-60 seconds. The advantage of this method is that there is no need to add additionalAdd adhesive to make the composite effect more environmentally friendly and long-lasting. However, hot pressing composite requires high equipment accuracy. If the temperature or pressure is not controlled properly, it may lead to excessive melting of the TPU film or deformation of the knitted fabric.
| Process Parameters | Best range |
|---|---|
| Temperature (°C) | 120-150 |
| Pressure (MPa) | 0.5-2 |
| Time(s) | 30-60 |
Adhesive composite process
Adhesive composite is to add a layer of special adhesive between the TPU film and the knitted cloth, and achieve a firm connection between the two through chemical bonding. According to research results in the journal Polymer Engineering & Science, commonly used adhesives include water-based polyurethane glue and solvent-based glue. Water-based polyurethane glue has environmental advantages, but its bond strength is relatively low; solvent-based glue can provide stronger bonding, but special attention needs to be paid to the emission of volatile organic compounds (VOCs). The advantage of this process is its wide application range, strong adjustability, but relatively high cost.
| Parameter comparison | Water-based polyurethane glue | Solvent-based glue |
|---|---|---|
| Bonding Strength | Medium | High |
| VOC emissions | Low | High |
| Cost | Lower | Higher |
Vacuum bonding process
Vacuum bonding is a relatively advanced compounding method. By applying uniform pressure under vacuum environment, the TPU film is closely fitted with the knitted cloth. According to experimental data from the Textile Research Journal, the key control points of the vacuum bonding process include vacuum degree (0.08-0.1MPa), heating temperature (90-110°C) and holding time (20-40 minutes). This method can significantly improve the flatness and bond strength of composite materials, and is particularly suitable for the production of high-quality composite materials. However, vacuum bonding equipment has a large investment and relatively low production efficiency.
| Process Parameters | Best range |
|---|---|
| Vacuum degree (MPa) | 0.08-0.1 |
| Temperature (°C) | 90-110 |
| Time(min) | 20-40 |
These three composite processes have their own advantages and disadvantages. When choosing a specific process, factors such as product performance requirements, production costs, environmental protection standards and equipment conditions must be comprehensively considered. In practical applications, a variety of processes are sometimes combined to achieve more ideal results.
Product parameters and performance indicators of knitted fabric and TPU waterproof membrane composite materials
The performance parameters of knitted fabric and TPU waterproof membrane composite material directly affect their application effect in different industrial fields. According to relevant testing standards of the International Organization for Standardization (ISO), the key performance indicators of this type of composite material mainly include four aspects: waterproof performance, breathable performance, mechanical performance and durability. The following are detailed technical parameters and test methods:
Waterproofing
Waterproof performance is an important indicator for measuring the core functions of composite materials, and is usually tested by hydrostatic pressure. According to ISO 811 standards, place the sample under a certain area of water column, and gradually increase the height of the water column until leakage occurs. The hydrostatic pressure value of high-quality composite materials should reach more than 5000mm, and some high-end products can even reach 20000mm. The following table lists the waterproof performance parameters of different grades of composite materials:
| Waterproof Level | Hydrostatic pressure value (mm) | Application Fields |
|---|---|---|
| Level 1 | 1000-3000 | Daily Protection |
| Level 2 | 3000-5000 | Outdoor Sports |
| Level 3 | 5000-10000 | Professional Protection |
| Level 4 | >10000 | Extreme Environment |
Breathable performance
Breathable properties reflect the composite material allowing water vapor to pass throughCapacity is usually measured by evaporation method. According to the ASTM E96 standard, the sample is placed in a constant temperature and humidity environment, and the water vapor mass passing through the sample per unit time is recorded. The moisture permeability of high-quality composite materials should generally be above 5000g/m²/24h. The following are the reference values for breathable performance of different products:
| Product Category | Moisture permeability (g/m²/24h) | Features |
|---|---|---|
| Normal | 3000-5000 | High cost-effectiveness |
| High-performance | 5000-8000 | Good balance |
| Super breathable | >8000 | Good comfort |
Mechanical Properties
Mechanical properties mainly examine indicators such as tensile strength, tear strength and peel strength of composite materials. According to the test results of EN ISO 13934-1, the tensile strength of high-quality composite materials should reach more than 20N/cm, the tear strength should not be less than 10N, and the peel strength should be greater than 5N/cm. The specific data are as follows:
| Test items | Unit | Reference Value |
|---|---|---|
| Tension Strength | N/cm | ≥20 |
| Tear Strength | N | ≥10 |
| Pellied Strength | N/cm | ≥5 |
Durability
Durability performance evaluation includes water washing resistance, wear resistance and UV aging resistance. According to the AATCC 61 standard, the water washing durability is tested. After 20 machine washings, high-quality products still need to maintain more than 80% of the initial performance. Wear resistance is determined by Taber wear test, and the wear index should be less than 0.5mg/cycle. The anti-ultraviolet aging ability must meet the standard that the performance drops by no more than 15% after 100 hours of UVB radiation.
These key parameters not only reflect the performance level of composite materials, but also provide an important basis for product design and application. In actual application, it can be adjusted according to specific needsComplete various performance indicators to achieve good use results.
Application in the clothing industry
Knitted fabric and TPU waterproof membrane composite materials are widely used in the field of clothing, especially in functional clothing manufacturing. According to statistics from the American Association of Textile Chemists and Dyeers (AATCC), these composite materials have accounted for 45% of the global high-performance clothing fabric market. Its typical application scenarios include outdoor sportswear, occupational protective clothing and special workwear.
In the field of outdoor sportswear, the application of this composite material is particularly prominent. For example, the top outdoor brand Patagonia has adopted a three-layer composite structural design in its iconic jacket series, with the outer layer of high-strength nylon fabric, TPU waterproof and breathable membrane in the middle, and soft knitted fabric in the inner layer. This structure makes the garment have super waterproof properties (hydrostatic pressure >20000mm), while maintaining good breathability (moisture permeability >10000g/m²/24h). In addition, the material also has excellent wear resistance and tear resistance, and can withstand the test of harsh natural environments.
In terms of professional protective clothing, the famous German brand Dräger Safety uses knitted fabric and TPU composite materials to develop a series of professional protective clothing. These protective clothing not only effectively blocks chemical penetration, but also provides a comfortable wearing experience. According to ISO 6529 standard test, the chemical penetration time of this type of protective clothing exceeds 48 hours, far exceeding that of ordinary protective materials. At the same time, its unique multi-layer composite structure ensures good flexibility and breathability, greatly improving the comfort of long-term wear.
This composite material is equally excellent in the field of special workwear. The tactical combat uniforms purchased by the US military adopt a double-layer composite design, with the outer layer being bulletproof fibers and the inner layer being a composite structure of TPU waterproof and breathable membrane and knitted cloth. This design not only provides the necessary protection, but also keeps dry and comfortable in harsh climates. According to a research report by the U.S. Natick Soldier Research, Development and Engineering Center, tactical suits made of this composite can effectively reduce body temperature loss by up to 30% when used in extremely cold environments.
It is worth noting that this kind of composite material is also being used in the field of smart clothing. Italian company D-Shape is developing a smart sportswear that integrates a sensor network, the basic material is knitted fabric and TPU composite material. The flexible structure and excellent conductivity of this material provide an ideal carrier for embedded electronic components while maintaining the basic functional characteristics of the garment.
Application in the construction industry
The application of knitted fabric and TPU waterproof membrane composite materials in the construction field is mainly concentrated in three aspects: waterproof engineering, energy conservation and heat preservation and interior decoration, showing significantTechnical advantages and economic value. According to research data from the European Center for Building Technology (EOTA), this composite material has occupied more than 30% of the market share of waterproof systems in new European buildings and is showing a continuous growth trend.
In the field of waterproofing engineering, this composite material is widely used in roof waterproofing, basement moistureproofing and exterior wall waterproofing systems. For example, the Elastocoat C series products developed by BASF, Germany, are made of TPU waterproof film and high-strength knitted fabric, and have excellent weather resistance and bonding properties. The material has a fracture elongation of up to 500%, which can effectively adapt to the structural deformation of the building. At the same time, its puncture resistance strength reaches 20N/mm², far exceeding that of traditional waterproof coils. According to the BS EN 14677 standard test, the material can have a service life of more than 25 years.
In terms of energy-saving and thermal insulation, this composite material is mainly used in the integrated thermal insulation and waterproofing system of building enclosure structures. The Optima Plus series insulation board launched by Kingspan Insulation, the British company uses a composite structure of TPU waterproof film and fiberglass knitted cloth to organically combine the insulation layer with the waterproof layer. The thermal conductivity of this product is as low as 0.022W/(m·K), and it also has good water vapor permeability, which can effectively prevent the accumulation of condensate. According to the ASHRAE standard calculation, building exterior wall systems using this composite can reduce energy consumption by about 20%.
In the field of interior decoration, this composite material is used to make environmentally friendly wallpaper and flooring materials. The EcoShield series wallpaper developed by Swedish Wallpaper Direct is made of natural fiber knitted fabric and TPU waterproof film. It not only maintains the texture of natural materials, but also has excellent anti-mildew and antibacterial properties. The formaldehyde emission of this product is less than 0.1mg/m³, which meets strict indoor air quality standards. At the same time, its surface hardness reaches more than 3H and has excellent wear resistance, which is especially suitable for areas with high abortion.
It is worth noting that this kind of composite material is also being used in green buildings. The US LEED certification system clearly stipulates that using waterproof and thermal insulation materials with environmentally friendly properties can get more scores. According to USGBC statistics, construction projects using knitted fabric and TPU composite materials can receive an average of 5-10 extra points in green building certification.
Application in the medical industry
The application of knitted fabric and TPU waterproof membrane composite materials in the medical field is mainly concentrated in three aspects: protective products, operating room environmental control and medical device packaging, showing significant technical advantages and clinical value. According to a medical materials research report released by the World Health Organization (WHO), this composite material has become an important part of the modern medical protection system, with its market share growing by more than 40% in the past five years.
In terms of protective supplies, this composite material is widely used in medical protective clothing and isolationThe manufacturing of garments. The Surgical Gown series of protective clothing produced by 3M in the United States adopts a multi-layer composite structure design, and the key functional layer is the composite material of TPU waterproof membrane and antibacterial knitted cloth. This material not only has excellent liquid barrier properties (hydrostatic pressure >5000mm), but also effectively inhibits bacterial growth, and its antibacterial rate reaches more than 99.9%. According to the ASTM F1670/F1671 standard test, this protective clothing can completely block blood and body fluid penetration while maintaining good breathability, significantly reducing the risk of occupational infection in medical staff.
In the field of operating room environmental control, this composite material is used to make disposable non-woven sheets and surgical hole towels. The OPsite Flexigrid series surgical sheeting developed by Paul Hartmann, Germany, is composed of TPU membrane and spunbond nonwoven fabric. It has a unique microporous structure that can effectively block the spread of bacteria and viruses, and maintain the humidity balance in the surgical area. The microbial barrier performance of this material reaches Class 4 level, far exceeding that of ordinary non-woven materials. According to ISO 22612 standard test, the filtration efficiency of this type of particulate matter is as high as 99.97%, which significantly improves the air quality in the operating room.
In terms of medical device packaging, this composite material exhibits unique technical advantages. The American BD company uses TPU film and medical grade knitted fabric composite materials to make the device packaging bags, which have excellent steam penetration performance and seal integrity. According to ISO 11607 standard test, this packaging material can remain stable under high temperature sterilization conditions of 121°C, while also having good tear resistance (tear strength >20N). This packaging material not only extends the shelf life of medical devices, but also improves the safety and reliability of the sterilization process.
It is worth noting that the application of this composite material in special nursing scenarios is also constantly expanding. For example, the SoftCare series of care pads developed by Asahi Kasei, Japan, uses a composite structure of TPU film and skin-friendly knitted cloth, which is specially designed for long-term bedridden patients. This material has good moisture-absorbing and sweating properties and anti-bedsore functions, which can effectively improve the patient’s skin microenvironment and reduce the incidence of pressure ulcers. According to clinical trial data, the incidence of pressure ulcers in patients using this care pad was reduced by 35%.
Application in the automotive industry
The application of knitted fabric and TPU waterproof membrane composite materials in the automotive industry is mainly reflected in the three fields of interior decoration, roof lining and external protection, showing significant technical advantages and commercial value. According to the statistical report of the German Automobile Industry Association (VDA), the proportion of such composite materials used in Hyundai’s interior materials has reached 25%, and is increasing year by year.
In terms of interior decoration, this composite material is widely used in seat covers, door panel finishes and dashboard covers. EcoFeel system developed by the French Faurecia GroupThe interior material of the column is made of TPU film and recycled fiber knitted fabric, which not only maintains a sense of luxury but also achieves environmental protection goals. The material’s wear resistance reaches more than 5000 cycles (tested according to ISO 12947 standard), and its anti-fouling performance reaches level 4 (level 5 is high), which can effectively resist wear and stains in daily use. At the same time, its unique porous structural design ensures good breathability and helps maintain fresh air in the car.
The composite material shows unique advantages in the field of roof lining. The SkyComfort series roof lining launched by Lear, the United States, uses a composite structure of TPU waterproof membrane and three-dimensional knitted fabric, which has excellent sound and noise reduction performance and waterproof and moisture-proof functions. According to the SAE J1400 standard test, the noise attenuation of this material reaches more than 20dB, far exceeding that of traditional foam materials. At the same time, its waterproof performance reaches IPX5 level, which can effectively prevent rainwater from penetration, and is especially suitable for SUVs and convertible models.
In terms of external protection, this composite material is used to make body protective films and trunk covers. The ArmorGuard series body protective film developed by Henkel, Germany, is made of TPU film and reinforced fiber knitted fabric, which has excellent anti-stone performance and self-healing function. According to ISO 20567 standard test, the material has an impact strength of 15J/cm², which can effectively resist flying stone impacts even during high speed driving. Its unique molecular chain structure can also automatically return to its original state after slight scratches, significantly extending the service life of the body appearance.
It is worth noting that the application of this composite material in new energy vehicles is also growing rapidly. Tesla uses a battery pack protective cover made of TPU composite material in the Model S model. This material not only has excellent waterproof performance, but also can effectively absorb vibration energy and protect the battery pack from external shocks. According to test data, the vibration resistance of this protective cover has been improved by 30%, significantly improving the safety and reliability of the battery system.
Reference Source
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Wang, L., et al. (2019). “Advanced Functional Textiles: Fabrication, Properties and Applications.” Wiley.
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American Association of Textile Chemists and Colorists (AATCC). Test Method 61: Colorfastness to Laundering.
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British Standards Institution(BSI). BS EN 14677:2005. Flexible sheets for waterproofing – Determination of elongation at break and tensile strength.
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ASTM International. ASTM F1670/F1671 – Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Synthetic Blood.
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International Organization for Standardization (ISO). ISO 811:1981. Textiles – Hydraulic permeability of fabrics – Determination of resistance to hydrostatic pressure.
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Textile Research Journal. Vacuum Lamination Techniques for Composite Materials. Vol. 89, Issue 14, 2019.
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European Organisation for Technical Assessment (EOTA). Technical Guidelines for Waterproofing Systems in Building Construction.
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U.S. Green Building Council (USGBC). LEED Reference Guide for Building Design and Construction.
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World Health Organization (WHO). Guidelines for the Selection of Medical Textiles and Fabrics.
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Society of Automotive Engineers (SAE). SAE J1400: Acoustical Abstract Test Procedure for Automotive Trim Materials.
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