TPU film has the advantages of low temperature resistance, high toughness, high strength, environmental degradation and "breathability". It is replacing PVC, EVA, artificial leather and other materials in various fields. The consumption in China is also increasing. With the continuous enhancement of environmental awareness in the whole society, with the further development of technology, the application scope of TPU has been expanding.
TPU waterproof and moisture permeable membrane is mainly used in racing clothing, locomotive wear, golf suit, mountaineering shoes, shower curtain, tablecloth, raincoat, baby bib, nautical clothes, fishing pants, Snow Jacket, wind coat, cold jacket, ski suit, skiing gloves, mountaineering suit, hunting suit, flush suit, horse coat, front and battle suit. Lighting accessories, mobile phone waterproof accessories and so on.
1、 characteristics of TPU film
TPU film is made by melt extrusion of TPU material particles. The film has the advantages of low temperature resistance, high toughness, high strength, environmental degradation, "respirability" and so on. It is gradually replacing the materials such as PVC, EVA and artificial leather, especially in the field of film. For example, as the thickness of TPU film is thicker (0.5~2 millimeter), all kinds of sports shoes and outdoor mountaineering shoes are used in large amount of consumption, and sports equipment mainly concentrated in water charging boats, inflatable boats and water kites, mainly using polyether TPU film, used in home textiles, submachine clothing, outdoor supplies, medical treatment, and medical treatment. Waterproof and moisture permeable TPU film.
2、processing technology and characteristics of TPU film
TPU can produce TPU films by blow molding and tape casting.
Blow molding method: the raw material is melted and plasticized through a hot extruder, from the machine head to the die head, compressed and air blown up and drawn, then curled and cut.
Casting process: the raw material is melted and plasticized through a hot extruder. It is extruded through a slit die and poured into the cooling roller to make the raw material cool rapidly and then stretch, cut and coiling. The effect of crystallinity on thin films, proper crystallization, good appearance and excellent mechanical properties. If the crystallization is too strong, it will lead to the rupture of the melt, which leads to the agglomeration of the extrusion, and the many parts of the film reunion, and the film is rough and the mechanical properties are not good.
3、 the influence of the extrusion rate of TPU film on the film
After extrusion rate increases to critical rate, the extrusion distortion of TPU film will occur. Distortion can be pided into surface distortion and overall distortion. Therefore, under the condition of ensuring the good appearance performance of the film, selecting the appropriate extrusion rate is helpful to improve the production.
4、characteristics of TPU thin film with high moisture permeability
(1) microporous membrane
Generally, polytetrafluoroethylene is used as the raw material. After expansion and stretching, a porous film itself has a porous structure, the pore size is 0.2~10um, only the water vapor can be permeated, so the water vapor emitted in the body can effectively diffuse through the aperture, and the water droplet can not permeate, thus the effect of waterproof perspective can be achieved.
(2) hydrophilic nonporous membrane
Polycarbamate (TPU) is used as the main material to introduce water parent, surface and bulk homogeneous and compact structure. The surface contains a certain hydrophilic group. The water vapor molecules are "captured" in the form of hydrogen bond, and the water vapor is "transmitted" through the molecular chain and the internal and external pressure difference water vapor to achieve excellent waterproof. Moisture permeability.
Compared with the traditional microporous membrane, the TPU molecular permeable membrane has a certain degree of resistance to surface active agents, high water osmotic pressure, selective osmosis, strong tearing resistance, complete isolation of bacteria and odors, and low cost.