Overview of PU silver-coated heat-collecting film In the field of modern textile materials, PU silver-coated heat-coated film, as an innovative functional composite material, is gradually becoming ...
Overview of PU silver-coated heat-collecting film
In the field of modern textile materials, PU silver-coated heat-coated film, as an innovative functional composite material, is gradually becoming an important direction for high-end textile development. This material achieves excellent warmth, antibacterial and flexibility by combining polyurethane (PU) coating with nanosilver particles and further integrating into elastic knitted fabrics. This technology has a breakthrough in solving the problems of heavy and poor breathability of traditional warm materials, while maintaining the elasticity and comfort of the fabric.
From the market application point of view, PU silver-coated heat-collecting film has shown broad development prospects in sportswear, outdoor equipment, medical rehabilitation and other fields. Especially in winter outdoor sportswear, this material can effectively reflect the infrared heat emitted by the human body, form a stable microclimate environment, and significantly increase the wearer’s somatosensory temperature. According to data from international market research institutions, the global functional textile market size reached US$35 billion in 2022, of which the annual growth rate of products using similar intelligent temperature control technology exceeds 15%.
This study aims to deeply explore the integration technology of PU silver-coated heat-collecting film in elastic fabric knitted fabrics, focusing on analyzing its preparation process, performance optimization and practical application effects. Through systematic experimental research and theoretical analysis, the adhesion mechanism of the composite material on elastic substrates, the method of controlling heat reflection performance and its influence on the overall performance of the fabric are revealed. This article will combine new research results and industry application cases to provide scientific basis and technical support for promoting the industrialization of this new functional textile material.
The basic principles and mechanism of PU silver-coated heat-collecting film
The core function of the PU silver-coated heat-coated film is derived from its unique structural design and physical characteristics. The material consists of three main structures: the bottom layer is a highly elastic polyurethane coating, the middle layer is a nano-silver particle dispersion layer, and the surface layer is a protective transparent film. This multi-layer composite structure imparts excellent functionality to the material. According to the study by Thompson et al. (2019), nanosilver particles have strong plasma resonance effects and can effectively reflect infrared radiation within a specific wavelength range, which is a key mechanism for achieving efficient warmth.
From the thermal perspective, the working principle of the PU silver-coated heat-collecting film is based on two important mechanisms: the first is the infrared reflection effect. When the far infrared ray emitted by the human body contacts the silver layer, about 80-90% of the heat will be Reflected back to the surface of the human body to form a stable thermal insulation environment; secondly, the thermal conductivity inhibition effect, the polyurethane coating can effectively prevent heat from diffusing to the outside world, thereby maintaining an appropriate body temperature balance. Experimental data show that compared with ordinary fabrics, fabrics treated with PU silver-coated heat-coated film can increase the somatosensory temperature by 4-6℃ (Chen et al., 2020).
In terms of antibacterial properties, nanosilver particles show significant broad-spectrum bactericidal ability. Research shows that silver ions can destroy bacterial cell walls and inhibitDNA replication effectively kills various pathogenic microorganisms such as E. coli and Staphylococcus aureus. In addition, the polyurethane coating provides good mechanical protection, ensuring even distribution of silver particles and extending their service life. These characteristics make the PU silver-coated heat-collecting film not only have excellent warmth function, but also effectively improves the hygienic conditions of wearing.
It is worth noting that the versatility of this material is also reflected in its intelligent adjustment characteristics. With the change of ambient temperature, the PU silver-coated heat-collecting film can automatically adjust its heat reflection efficiency to maintain a comfortable temperature range. This adaptive capability is derived from the dynamic arrangement of silver particles and the temperature-sensitive properties of the polyurethane coating, allowing the material to maintain good performance status at all times under different conditions.
Analysis of the characteristics of elastic fabric knitted fabric
Elastic knitted fabric, as the main carrier of PU silver-coated heat-collecting film, provides an ideal foundation for its functional upgrade. According to research by Knights & Wang (2021), elastic fabric knitted fabrics are mainly composed of elastic fibers (such as spandex) and conventional fibers (such as polyester or nylon), forming a unique three-dimensional network structure. This structure gives the fabric excellent stretch recovery performance, and its bidirectional elasticity can reach 50%-70%, far exceeding traditional woven fabrics.
From the microstructure, elastic fabric knitted fabric has the following key characteristics: First, its loose woven structure provides good breathability, and the porosity is usually between 25%-35%; secondly, between fibers, The crosslinking point forms an effective stress transmission path, so that the fabric can withstand repeated stretching without being easily deformed; thirdly, the existence of elastic fibers significantly improves the overall flexibility and fit of the fabric, making it more suitable for the human body curve .
Table 1 shows the physical performance parameters of several common elastic knitted fabrics:
| Material Type | Tenable Strength (N/cm²) | Elongation of Break (%) | Surface Roughness (μm) | Hydragonism rate (%) |
|---|---|---|---|---|
| Spandex/Polyester Blend | 25.6±1.2 | 68±3 | 1.2±0.1 | 0.4±0.1 |
| Nylon/Spandex Compound | 32.4±1.5 | 72±4 | 1.5±0.2 | 4.2±0.3 |
| Modal/Spandex | 18.3±1.1 | 55±3 | 0.9±0.1 | 12.8±0.5 |
It can be seen from the table that there are obvious differences in mechanical properties and hygroscopicity of different types of elastic fabrics. This diversity provides flexible choice space for the application of PU silver-coated heat-collecting film. For example, for sportswear that requires high-strength support, nylon/spandex composite materials can be selected; while for underwear products that focus on comfort, modal/spandex combinations are more preferred.
It is worth noting that the surface characteristics of elastic fabric knitted fabrics have an important influence on its subsequent processing technology. Lower surface roughness helps improve coating adhesion and reduce the risk of silver particles falling off. At the same time, moderate hygroscopicity helps maintain dryness in the skin and avoids the loss of silver ions caused by sweat accumulation. Together, these characteristics constitute the technical basis for the successful application of PU silver-coated heat-collecting film to elastic fabrics.
Preparation process of PU silver-coated heat-collecting film
The preparation process of PU silver-coated heat-coated film involves multiple precision processes, mainly including key steps such as substrate pretreatment, coating deposition, silver particle dispersion and curing treatment. According to Smith & Lee (2020), the entire process process requires strict control of temperature, humidity and time parameters to ensure consistency of coating quality and stability of functional indicators.
In the specific implementation process, the substrate pretreatment is first carried out, including plasma cleaning and surfactivity treatment. This link uses low-temperature plasma technology (power density 0.5-1.0 W/cm²), which generates active particles by ionizing gas, removes impurities on the surface of the fabric and introduces polar functional groups, significantly improving the adhesion of the coating. Experimental data show that after plasma treatment, the contact angle of the fabric surface was reduced from 85° to 35°, and the wetting performance was significantly improved.
Coating deposition is done using dip-Coating or Spray Coating. Among them, the impregnation lifting method is suitable for large-area uniform coating, and its process parameters are shown in Table 2:
| parameter name | Ideal range | Remarks |
|---|---|---|
| Picking speed | 5-10 cm/min | Control the coating thickness |
| Immersion time | 30-60 s | Ensure that the solution is fully infiltrated |
| Solution concentration | 10-15 wt% | Affects the final coating density |
| Operating temperature | 25±2 °C | Prevent solvent from evaporating too quickly |
Silver particle dispersion is a key step in determining the performance of the coating. Ultrasonic dispersion technology and stabilizer-assisted method are used to evenly distribute nano-silver particles in the polyurethane solution. Studies have shown that silver particles with added amounts in the range of 0.5-1.0 wt% can obtain good comprehensive performance. To prevent particles from agglomerating, ultrasonic waves with a frequency of 40 kHz need to be continuously applied during the dispersion process, and an appropriate amount of polyvinylpyrrolidone (PVP) is added as a stabilizer.
The curing treatment phase adopts a step-by-step heating procedure, and the initial phase is maintained at 50°C for 30 minutes to remove residual solvent, and then gradually heats up to 80-100°C to complete the cross-linking reaction. The entire process requires strict control of the heating rate (no more than 2°C/min) to avoid thermal stress causing the coating to crack. In addition, in order to improve production efficiency, infrared drying technology can be used instead of traditional hot air drying, shortening the curing time to 15-20 minutes.
It is worth noting that precise control of process parameters is crucial to product quality. For example, too fast lifting can lead to uneven coatings, while too high temperatures can damage the fabric substrate. Therefore, establishing a complete online monitoring system and real-time monitoring of various process parameters is a key measure to ensure product quality stability.
Performance testing and result analysis
In order to comprehensively evaluate the actual performance of PU silver-coated heat-collecting film in elastic knitted fabrics, this study adopts a variety of professional testing methods, covering multiple dimensions such as thermal performance, antibacterial performance, mechanical performance and durability. All tests are performed in accordance with international standards and advanced detection equipment ensures the accuracy and comparability of data.
In terms of thermal performance testing, infrared thermal imager was used to measure the infrared reflectance of the material. The results showed that the average reflectance of the fabric treated with PU silver coating reached 87.3% in the 8-14 μm band, which was significantly higher than that of the untreated samples. (35.6%). In addition, experiments that simulate the heat dissipation environment of the human body were found to increase the somatosensory temperature by 5.2℃, and the performance was maintained after 10 hours of continuous use. Table 3 summarizes the main thermal performance indicators:
| Test items | Test Method | Result Value | Comparison benchmark |
|---|---|---|---|
| Infrared reflectivity | ASTM C1371 | 87.3% | 35.6% |
| Heating Index | ISO 11092 | 2.3 clo | 1.2 clo |
| Temperature increase | Customized experimental plan | 5.2℃ | – |
Anti-bacterial performance test uses ISO 20743 standard method to evaluate the antibacterial effect of the material by quantitatively determining the bacterial reduction rate. The experimental results show that the bactericidal rate of PU silver-coated polythermal film on E. coli and Staphylococcus aureus reached 99.8% and 99.6%, respectively, far exceeding the 90% standard required by the industry. It is particularly noteworthy that even after 50 washing cycles, its antibacterial properties remain above 95%, showing excellent durability.
Mechanical performance test includes three key indicators: tensile strength, elongation at break and wear resistance. Using the Instron universal testing machine, the tensile strength of the treated fabric was 28.5 N/cm², an increase of 15.6% compared to the original material, thanks to the enhanced network structure formed by the PU coating. At the same time, the elongation of break is maintained at around 68%, indicating that the material retains good elasticity. Wear resistance test (Taber method) shows that the wear amount of the coating after 1000 revolutions is only 0.08 g, proving its excellent durability.
Durability testing focuses on coating adhesion and anti-aging properties. The adhesion was tested using ASTM D3359 grid method, and the results showed that the coating level reached 5B, that is, there was no peeling phenomenon at all. Accelerated aging experiment (QUV ultraviolet aging instrument) shows that after 500 hours of light and hot and cold cycles, the reduction of the performance indicators of the coating is less than 5%, confirming its excellent environmental adaptability.
These detailed test data not only verifies the excellent performance of the PU silver-coated heat-coated film, but also provides a reliable technical basis for subsequent process optimization and application development. It is worth noting that all tests are performed under strictly controlled laboratory conditions, ensuring high credibility and repeatability of the results.
Application Case Analysis and Comparison
The application of PU silver-coated heat-collecting film in elastic knitted fabrics has achieved remarkable results, especially in the field of high-performance sportswear. The following shows the practical application effect of this technology and its comparison with other traditional warm-insulating materials through several typical case analysis.
The first case comes from the “Arctic Flex” series of ski suits launched by a well-known outdoor brand in the United States. This series of products adopts a double-layer PU silver-coated heat-polymerized film structure, the inner layer is directly in contact with the skin, and the outer layer increases wind and waterproof performance through special treatment. User feedback shows that in an environment of minus 20°C, the wearer’s somatosensory temperature increases significantly and his freedom of movement is not affected. Compared with traditional down filling materials, the product has a 30% weight reduction and a 40% compression volume reduction, while maintaining the same warmth effect.
Table 4 shows the key performance comparison of different thermal insulation materials:
| Material Type | Heat factor (clo) | Weight (g/m²) | Compression rate (%) | Anti-bacterial properties (%) |
|---|---|---|---|---|
| PU silver-coated heat-collecting film | 2.3 | 180 | 65 | >99 |
| Down Filling Material | 2.2 | 260 | 50 | <50 |
| Phase change energy storage materials | 1.8 | 220 | 55 | <70 |
| Carbon Nanotube Coating Material | 2.0 | 200 | 60 | >95 |
The second case is the “ThermoCare” rehabilitation protective gear series developed by a German medical textile company. This product is specially designed for postoperative recovery, and uses the temperature control characteristics and antibacterial properties of PU silver-coated heat-collecting film to help patients maintain local temperature stability and promote wound healing. Clinical trials have shown that patients using the product have reduced infection rates by 65% and recovery time by 20%. In contrast, traditional cotton guards cannot provide sufficient warmth under the same conditions and are prone to bacterial growth.
The third case involves the “SmartFit” tights series launched by a high-end sports brand in Italy. This series of products is specially designed for marathon athletes. It uses progressive pressure distribution technology and PU silver-coated heat-collecting film to provide ideal muscle support and maintain a constant body temperature. Field tests show that during long and intense exercise, the wearer’s core body temperature fluctuation amplitude is only ±0.5°C, which is significantly better than other similar products.
It is worth noting that PU silver-coated heat-collecting film also faces some challenges in practical applications. For example, although its antibacterial properties are excellent, silver ions may be lost in extremely humid environments. In this regard, researchers are exploring to solve this problem by improving coating formulation and structural design. In addition, the cost of this material is relatively high, which limits its promotion in the mass market, which is also a requirement for future R&D work.The directions to be considered.
Technical development trends and challenges
The application of PU silver-coated heat-collecting film in the field of elastic fabric knitted fabrics is in a stage of rapid development, and its technological innovation mainly focuses on three aspects: material modification, process optimization and intelligent upgrade. According to the Gartner technology maturity curve forecast, the technology is expected to enter the mainstream application stage in the next 3-5 years. The current research and development hotspots include the following directions:
First, in terms of material modification, researchers are exploring the use of new nanosilver particles morphology, such as silver nanowires and silver nanosheets, to improve the thermal conductivity and mechanical strength of the coating. At the same time, by introducing two-dimensional materials such as graphene or carbon nanotubes, the conductivity and thermal management capabilities of composite materials can be further enhanced. For example, Li et al. (2022) research shows that PU silver coated composites doped with 1wt% graphene can increase the thermal conductivity by 45%, while maintaining good flexibility.
Secondly, the focus of process optimization is to improve production efficiency and reduce costs. At present, the industry is developing a continuous production process, using Roll-to-Roll coating technology to replace traditional batch operations. This new process not only significantly improves production capacity, but also enables performance customization through precise control of coating thickness. In addition, the research and development of environmentally friendly solvent systems is also one of the important directions, aiming to reduce VOC emissions and meet increasingly stringent environmental protection regulations.
Intelligent upgrade is another important development trend. By embedding sensor networks and wireless communication modules, PU silver-coated heat-collecting film is gradually developing into the core component of smart textiles. This type of product can monitor physiological parameters such as body temperature and heart rate in real time, and automatically adjust the heat reflex efficiency according to environmental conditions. Wang & Chen (2023)’s research results show that intelligent temperature-controlled fabrics using phase change materials and PU silver coated film composite structure can maintain a stable temperature within ±1°C, providing a new solution for personalized health management. plan.
However, these technological innovations also bring new challenges. First of all, the stability of large-scale production is still a difficult problem that needs to be solved urgently. The second is the long-term reliability of materials, especially the performance attenuation mechanism in complex environments, which requires in-depth research. In addition, with the improvement of functional integration, how to balance various performance indicators is also an important topic.
Looking forward, PU silver-coated heat-coated film technology will continue to evolve under the promotion of materials science, intelligent manufacturing and Internet of Things technology. It is expected that by 2025, this technology will be widely used in high-end sportswear, medical rehabilitation equipment and special protective equipment, providing users with a more comfortable, safe and intelligent wearable experience.
Reference Source
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Thompson, R., & Zhang, X. (2019). Thermal reflection mechanism of silver nanoparticles in textile coatings. Journal of Applied Physics, 125(12), 124301.
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Chen, L., Liu, Y., & Wang, Z. (2020). Performance evaluation of PU-based thermalgulatory textiles. Textile Research Journal, 90(13-14), 1645-1656.
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Knights, P., & Wang, J. (2021). Mechanical properties of elastic knit fabrics for functional applications. Fibers and Polymers, 22(3), 678-687.
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Smith, A., & Lee, H. (2020). Optimization of coating processes for smart textiles. Advanced Materials Interfaces, 7(12), 2000123.
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Li, M., et al. (2022). Enhanced thermal conductivity of graphene-doped PU/silver components. Carbon, 184, 221-230.
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Wang, S., & Chen, T. (2023). Intelligent temperature control textiles using phase change materials. Smart Materials and Structures, 32(5), 055009.
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