Production method of polyurethane synthetic leather

The industrial production methods of polyurethane synthetic leather mainly include dry process and wet process.
1. Dry polyurethane synthetic leather
The dry-process production process generally takes release paper as the carrier. The polyurethane resin slurry is scraped and coated on the release paper (generally scraped once or twice), and then put into the oven to heat and dry to remove the solvent in the resin to form a continuous and uniform polyurethane film. Then, the adhesive is scraped and coated on the film, which is bonded with the base cloth. After drying and curing, the release paper is peeled off by the stripping device and the finished artificial leather and release paper are rolled separately. Polyurethane slurry coating agent, release paper and base cloth are three components of the dry process. Synthetic leather produced by dry process has dense film, excellent product strength, firm adhesion, less waste water produced in the process, but the product's sanitary performance is relatively poor, and the waste gas produced in the production process is seriously polluted.
2 Wet polyurethane synthetic leather
The wet method is mainly to make the slurry fully penetrate into the nonwoven gap through extrusion, and then put the nonwoven into the coagulation bath. The "DMF-H2O" system is used to make DMF continuously enter the coagulation bath from the resin solution, while the water enters the base cloth to make the PU gradually change from the dissolved state to the gel state and finally form a solid membrane. During the exchange process, due to the regulation of additives and the shrinkage of polyurethane, a large number of micro-pores will be formed, and a multi-layer structure with continuous porous layers will be obtained. Therefore, the synthetic leather produced by wet process has good moisture permeability and air permeability, soft, plump and lightweight feel, and is more rich in the style and appearance of natural leather.