The development process of PU leather

The development process of PU leather: the evolution from PVC to dry PU and wet PU

PU leather, or polyurethane synthetic leather, is a widely used synthetic material with excellent physical properties and broad application prospects. Since its birth, PU leather has experienced the evolution process from PVC to dry PU and wet PU. Its development process reflects the progress of science and technology and the continuous improvement of people's demand for material performance.

1. PVC stage

PVC, or polyvinyl chloride, was the first material used to make synthetic leather. As early as 1912, the German Fritz Klatte successfully synthesized PVC and applied for a patent in Germany. However, due to the inability to solve the hard and sometimes brittle problems encountered during PVC processing at that time, the application of PVC in the field of synthetic leather did not achieve a breakthrough. It was not until 1931 that the German company Farben used emulsion polymerization to realize the industrial production of polyvinyl chloride, and the manufacturing of PVC synthetic leather gradually got on the right track.

However, PVC synthetic leather has certain limitations in terms of physical properties and environmental protection. It has high hardness, poor feel, and is prone to aging and cracking. In addition, PVC will produce a large amount of toxic and harmful substances during the production and processing process, causing serious pollution to the environment. Therefore, people began to seek better synthetic leather materials.

2. Dry PU stage

PU, or polyurethane, is a polymer material with excellent physical properties and chemical stability. In the early 1950s, countries such as Germany, the United States, and Japan began to try to apply PU materials to the manufacture of synthetic leather. Compared with PVC synthetic leather, PU synthetic leather has significant advantages in physical properties and environmental protection.

Dry PU synthetic leather is an early form of PU synthetic leather. The production process mainly includes the preparation of PU resin, pretreatment of base fabric, coating and curing and other steps. Dry-process PU synthetic leather has excellent physical properties, such as wear resistance, folding resistance, cold resistance, etc., and it feels soft and comfortable. In addition, the production process of dry PU synthetic leather uses less solvents and causes less environmental pollution.

However, the production cost of dry-process PU synthetic leather is higher and the production efficiency is lower. In addition, dry-process PU synthetic leather has poor air permeability and moisture permeability, and it is easy for bacteria to breed in humid environments. Therefore, people began to seek more efficient, environmentally friendly and excellent-performance synthetic leather materials.

3. Wet PU stage

Wet PU synthetic leather is another form of PU synthetic leather. Its production process mainly includes the preparation of PU resin, impregnation, solidification, washing and drying of the base fabric. Compared with dry PU synthetic leather, wet PU synthetic leather has higher production efficiency, lower cost and better air permeability and moisture permeability.

In the production process of wet PU synthetic leather, PU resin is first dissolved in a solvent, and then goes through steps such as impregnation and solidification together with the base fabric to form synthetic leather. During the solidification process, the solvent is gradually replaced by water, and the PU resin gradually forms a solid structure. This process requires precise control of parameters such as temperature, humidity and setting speed to ensure the quality and performance of synthetic leather.

The excellent properties of wet-process PU synthetic leather make it widely used in various fields. For example, in the fields of clothing, bags, car interiors, etc., wet-process PU synthetic leather is very popular because of its softness, wear resistance, cold resistance, breathability and other characteristics. In addition, with the improvement of environmental awareness and the continuous advancement of technology, the production process of wet PU synthetic leather is paying more and more attention to environmental protection and sustainable development.

4. Conclusion

The evolution from PVC to dry PU to wet PU reflects technological progress and people's continuous improvement in material performance requirements. As an excellent synthetic material, PU synthetic leather has been widely used in various fields. In the future, with the continuous advancement of technology and people's increasing requirements for environmental protection performance, I believe that PU synthetic leather will have broader development prospects.