First, waterproof and moisture-permeable textile materials overview
Waterproof and moisture-permeable textile materials refer to textile materials that have the ability to prevent droplet penetration and rapid conduction of water vapor at the same time. Polytetrafluoroethylene (PTFE) is currently the most commonly used fluorine-containing waterproof and moisture-permeable material.
In 1976, the United States used PTFE and ordinary textile lamination composite to produce the first generation of waterproof and moisture-permeable materials, and successfully applied in the field of textile and clothing. At present, the waterproof and moisture-permeable textile materials on the market are still mainly fluorine-containing materials, with excellent performance and flexible production characteristics.
However, although the traditional fluorine-containing waterproof and moisture-permeable materials have good properties, the long-chain fluorinated polymers contained in the material will release toxic substances such as PFOA and PFOS for a long time, which will not only cause harm to the human body and affect health, but also because it is difficult to degrade in media such as water, atmosphere and soil, and easy to adhere to particulate matter and water sediments, so it is difficult to recycle related waste textile materials. Compared with traditional fluorine-containing materials, the new fluorine-free waterproof and moisture-permeable materials use other technical means to replace the harmful substances in the fluorine-containing materials, which eliminate the negative impact of the material on the human body and the environment while ensuring the original good waterproof permeability.
Second, the type of fluorine-free waterproof and moisture-permeable textile materials
For a variety of environmentally friendly fluorine-free waterproof and moisture-permeable textile materials that have emerged at present, they are first divided into hydrophilic non-porous type and hydrophobic porous type according to the waterproof and moisture permeable mechanism. For hydrophobic porous materials, according to the characteristics of the hydrophobic substances, they are subdivided into silicone waterproof and moisture-permeable textile materials, alkane long-chain waterproof and moisture-permeable textile materials, surface metallized waterproof and moisture-permeable textile materials and other categories. The following table is the classification and main performance indicators of fluorine-free waterproof and moisture-permeable textile materials.
Third, the application of fluorine-free waterproof and moisture-permeable textile materials
Although fluorine-containing materials have extremely low surface energy and good hydrophobicity, industrial applications have been relatively mature, but because the material is extremely difficult to degrade, there is a risk of high bioaccumulation and multi-toxicity, and fluorine-free waterproof and moisture-permeable textile materials in retaining the original good performance at the same time, eliminating the impact of fluorine on biology and the environment, can be used as functional materials in aerospace, medical, membrane distillation and protective clothing and other fields with high requirements for non-toxicity and environmental protection of materials.
3.1 Aerospace
With the development of lightweight in the aviation industry, high-efficiency fluorine-free waterproof and moisture-permeable textile materials can be used as interior materials in aircraft to adjust the relative temperature and humidity inside the cabin. Because it does not contain harmful elements such as fluorine, it can ensure the health of astronauts without polluting the space environment. In addition to lining materials, fluorine-free waterproof and moisture-permeable textile materials are also widely used in garbage recycling bags in spacecraft. In the aviation field, fluorine-free waterproof and moisture-permeable textile materials are mostly used in the internal ground and interior materials of civil aircraft silos, making them less susceptible to defacement and easy to clean.
3.2 Medical and membrane distillation fields
Medical dressings prepared from fluorine-free waterproof and wet-permeable textile materials can prevent ulceration caused by wound infection and impregnation of body fluids, while fluorine-free materials will not cause secondary harm to the patient's body. In addition, fluorine-free waterproof and moisture-permeable textile materials, as the main support materials for artificial organs, have also been widely used in artificial vascular stents, artificial cartilage and other aspects. As a core technology in the field of seawater desalination, membrane distillation is treated with fluorine-free, waterproof and moisture-permeable textile materials to remove volatile compounds, pollutants and toxic substances from seawater.
3.3 Protective clothing
People's love for outdoor sports makes outdoor functional clothing on the basis of cold and warmth function, and also needs to meet the requirements of human comfort such as wind and rain. Waterproof and moisture-permeable textile materials can not only protect the intrusion of rain and cold winds into the body, but also discharge the moisture generated by the human body outward. Therefore, waterproof and moisture-permeable materials can also be applied to the production of winter military uniforms, fire suits, combat uniforms and other military clothing, as well as medical protective clothing and other special protective clothing.