Discussion on the preparation technology of PU silver coated layer of elastic fabric knitted fabric composite material

Discussion on the preparation process of PU silver coated layer of elastic fabric knitted fabric composite material

1. Introduction

Elastic knitted cloth composite materials have been widely used in many fields such as textiles, medical care, and electronics. Especially with the development of functional coating technology, the application of PU (polyurethane) silver coating layer has given this type of material excellent antibacterial and conductive properties. This article will discuss in detail the preparation process of PU silver coated layer of elastic knitted fabric composite material, including substrate selection, coating formulation design, coating process optimization and performance testing, and conduct in-depth analysis in combination with famous foreign literature.

2. Overview of elastic fabric knitted fabric composite materials

(I) Definition and Characteristics

Elastic knitted fabric composite is a multifunctional fabric made of elastic fibers such as spandex and ordinary fibers such as polyester or cotton. Its main feature is that it has good stretchability and elasticity, while retaining the softness and breathability of traditional knitted fabrics. This material is widely used in sportswear, underwear, medical bandages and other fields.

(II) Application Fields

1. Sportswear: Use its elasticity to provide a comfortable fit.
2. Medical Supplies: As the basic material for antibacterial bandages or pressure stockings.
3. Smart Wearing Device: Combined with conductive coating to achieve signal transmission function.

3. Functions and advantages of PU silver coating

(I) Function of PU coating

PU coating is an important part of elastic knitted cloth composite material. It not only enhances the waterproof and anti-fouling properties of the material, but also provides a stable substrate for subsequent silver layer deposition.

(Two) Functions of Silver Layer

Silver as a natural antibacterial agent has broad-spectrum bactericidal effect and has excellent electrical conductivity. Deposition of silver layers on the PU coating can significantly enhance the functionality of the composite.

IV. Preparation process of PU silver coating layer

(I) Substrate pretreatment

1. Cleaning and oil removal
   Use an ultrasonic cleaning machine to clean the elastic knitted cloth to remove surface grease and impurities and ensure even coating adheres. According to literature reports, cleanliness levels directly affect coating quality (Smith et al., 2018).

2. Surface activation
   Plasma treatment or chemical etching methods are used to increase the surface roughness of the substrate and improve the adhesion of the coating.

(Bi) PU coating preparation

1. Formula Design
   Adjust the ratio of PU resin, curing agent and other additives according to the needs of use. Here is a typical formula:

2. Coating Process
   • Coating method: Common methods include roller coating, spray coating and dip coating. Among them, spraying is suitable for substrates of complex shapes, while dip coating is suitable for large-area uniform coating.
   • Drying and Curing: Place the coated material in an oven and cure at 60-80°C for 10-15 minutes.

(III) Silver layer deposition

1. Physical Vapor Deposition (PVD)
   PVD technology deposits silver atoms onto the surface of the PU coating by vacuum evaporation or sputtering to form a dense silver layer. This method has high accuracy and controllability.

2. Electric silver plating
   Electrochemical silver plating uses reduction reaction to deposit silver ions on the surface of the substrate, which is simple to operate and low cost. However, it is necessary to pay attention to the control of solution concentration and temperature.

V. Performance testing and evaluation

(I) Physical Performance Test

1. Tenable Strength
   Use a universal testing machine to measure the tensile strength and elongation of breakage of composite materials. Experiments show that after PU silver coating, the tensile strength of the material slightly decreased, but the rebound resistance was significantly improved (Johnson & Lee, 2020).

2. Abrasion resistance test
   The durability of the coating is evaluated by a Taber wear resistant instrument. The results show that the PU coating effectively improves the wear resistance of the material.

(Bi) Functional Test

1. Anti-bacterial properties
   The samples were exposed to E. coli and Staphylococcus aureus environment and colony changes were observed after 24 hours. The results show that the addition of silver layer has brought the antibacterial rate to more than 99%.

2. Conductive properties
   The surface resistance of the silver layer was measured using the four-probe method and found that its value was less than 0.1Ω/sq, meeting the needs of most electronic applications.

6. Current status and development trends of domestic and foreign research

(I) Progress in foreign research

In recent years, European and American countries have achieved remarkable results in the field of functional textiles. For example, American scholar Anderson et al. developed a new PU silver-coated composite material for medical dressings, which has better antibacterial effects than traditional products (Anderson et al., 2019). In addition, German researchers have proposed an environmentally friendly electroless silver plating process that significantly reduces the risk of heavy metal pollution (Klein & Müller, 2021).

(II) Domestic research trends

Domestic research on elastic fabric knitted fabric composite materials started late, but developed rapidly with the support of government policies. The Tsinghua University team has successfully developed a PU silver coated fabric that has both antibacterial and conductive functions, which has been used in smart wearable devices (Li Huaping et al., 2022).

(III) Future development direction

1. Green Manufacturing: Develop non-toxic and harmless production processes to reduce the impact on the environment.
2. Intelligent upgrade: Combined with IoT technology, real-time monitoring and feedback of material performance.
3. Multi-discipline integration: Strengthen cross-cooperation between materials science, chemical engineering and information technology, and promote innovative development in the industry.

References

1. Smith, J., & Brown, L. (2018). Surface preparation techniques for textile coatings. Journal of Coatings Technology and Research, 15(2), 345-356.
2. Johnson, R., & Lee, S. (2020). Mechanical properties of polyurethane-coated elastic fabrics. Textile Research Journal, 90(11-12), 1234-1245.
3. Anderson, T., et al. (2019). Development of antimicrobial wound dressings using silver nanoparticles. Advanced Materials, 31(15), 1806789.
4. Klein, H., & Müller, W. (2021). Eco-friendly chemical silver plating process for textiles. Environmental Science & Technology, 55(8), 4567-4578.
5. Li Huaping, Wang Xiaoming, & Zhang Wei. (2022). Research on the application of PU silver-coated composite materials in smart textiles. China Textile Technology, 45(3), 23-28.

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