Polyurethane (PU) synthetic leather to enter China since the 80’s has been developing rapidly due to excellent performance. 90’s, China’s PU leather industry gradually formed a complete industrial system, dry and wet method has hundreds of production lines, an unprecedented fierce competition in the market. As the market matures PU leather and China’s economic development, on the PU leather product quality, variety of requirements for getting higher and higher. At present, the foreign technical exchanges, many foreign advanced technology and innovative products soon to be sucked into the domestic, product development, manufacturers have been placed in a very important position. In this paper, the development of our company’s experience on the current PU leather product development and technical progress and we make a exchanges and explore.

Leather 1PU

1.1 Technical System PU leather technology sub-system and the Italian system of Japan, Taiwan Province of China, South Korea is Japan’s system technology. Japan’s chemical industry, chemical fiber and textile technical level very high, the number of PU resin, fabric and fiber research and development of more depth, more about the strength of products, water vapor permeability, PU film structure inherent performance, with high technical content. Such as Japan, South Korea produced superfine fiber leather and sports shoes and high-grade knitted fabrics superfine wet leather garments have shown a high level of technology. Italy synthetic leather products more affected by the leather processing technology, changes in the appearance of more high-quality art on the product design and fashion and more attention. Products are mainly for shoes, bags matching.

1.2 Wet Wet PU coating leather products because of their appearance, and feel closer to the inherent properties of natural leather, fast development. Wet process determines the level of wet PU leather products, the overall level. Wet coating technology with each passing day.

1.2.1 Wet PU coating membrane structure control wet PU coating membrane structure on the wet PU leather products, the inherent performance and feel great influence on the PU through the choice of raw materials and additives and add the proportion of cellulose control. Cellulose addition on wet PU leather products a great impact. Cellulose so that the cell membrane PU increase and improve the moisture-permeable membrane performance, while reducing the density of PU membrane. Sports shoes to wear because of their environment and internal performance requirements higher, often without cellulose, high-grade leather and rarely used. Because of the requirements to wear leather shoes and comfortable fabric, and internal performance requirements are slightly lower amount of cellulose can be added. For shoe leather, because of its moisture permeability is demanding, would increase the amount of cellulose. Can choose a special PU raw materials to control PU membrane structure, such as high viscosity of low solid content or low-viscosity high solid content of PU raw materials with, to adjust the structure of PU membrane. In addition, the wet process, the Promoter on the formation of PU membrane structure also played an important role, as a major means of regulation.

1.2.2 appearance to the appearance of PU leather products like leather, first of all, the appearance of wet coating products to close to the dermis. Italy to adopt more impregnation process, and then through the back of sanding to achieve that effect. However, impregnation products, such as the intrinsic properties of elasticity products as well. By process improvements, can now generate a both the intrinsic properties of products and product appearance impregnation style wet coating products. In addition, as with non-woven fabric or the back of machine-woven Fleece ways in which the appearance of PU leather close to the dermis. Sea-island supermicro fibers used to make non-woven fabric production wet PU leather, leather look most like. Fineness of the fiber reach 0.0011dtex, even 0.00011dtex, more like natural leather collagen fibers.

1.2.3 Wet technology hydrolysis of this technique is mainly used in the production of high-end sports shoes and high-grade leather sofa and decoration. PU leather is usually used in slurry Polyester PU, intolerant hydrolysis, and now has developed Polyether PU, improved wet PU leather hydrolysis performance. There are many manufacturers interested in the technology.

1.2.4 Non-woven wet coating technology as a wet-coated non-woven fabric of a new type has been increasingly wide range of applications, the wet coating technology has been of great importance to manufacturers. Non-woven strong scalability, easy-tensile deformation, made from wet PU leather products tend to have “paper”, which are the drawbacks of previous years has been plagued by a manufacturer, also affected the non-woven fabric in the wet coating applications.

At present, through equipment, non-woven and coating technology improvements, has been basically solved the wet-coated non-woven production and product performance problems. For a non-woven fabric wet PU leather has a lot to enter the market, and products are mainly for sports shoes and shoe leather. It is easy to cut, it is not easy edge features such as the appearance of more like leather, very bright prospect. The task now is to further improve the non-woven wet coating technology, improve product grade.

1.2.5 warp knitting cloth wet coating technology over the past few years warp knitted fabric only applies to wet coating process. Warp knitted fabric elastic elongation is too large, difficult to apply wet coating process. Japan used warp knitting machine-woven cloth lining the back of the method to improve the production of high-grade garment leather, but this process is too complex, requiring the use of special equipment. At present, Italy has been specifically designed to warp knitting cloth, make it easier for the wet coating process. Warp knitting cloth wet PU leather products has a special style, will certainly be developed and promoted.

1.3 dry transfer coating dry transfer coating Wet PU leather products is an important means of surface processing, but also the first developed PU leather technology, process technology has developed rapidly.

1.3.1 breathable technology of conventional dry-coated look good, but breathable poor, affecting the product performance. At present, Italy has developed with a breathable, moisture absorption function of dry coating technology, for high-grade leather shoes, increased wearing comfort. South Korea has also been promoting the technology.

1.3.2PU dry PU foam technology foaming technology dry ingredients and production operations were simple, its technology is superior to polyvinyl chloride (PVC) foam technology, but because of PU high cost to some extent affected the technologies and applications. Dry foam technology is now in the natural skin autopsy film on the skin surface are applied to improve the grade of leather. In addition, can be used in difficult dry film with conventional products, can also be used for apparel fabrics.

1.3.3 discoloration technology in recent years, membrane technology discoloration dry popular synthetic leather sector, Italy to change color of dry film technology and knead to combine stria process.