Introduction to the production of polyurethane synthetic leather
The industrial production methods of polyurethane synthetic leather mainly include dry and wet methods.
1. Dry polyurethane synthetic leather
The dry production process generally uses a release paper as a carrier, and the polyurethane resin slurry is blade coated on a release paper (generally one to two times), and dried in an oven to remove the solvent in the resin to form a continuous uniform polyurethane film. Then, the adhesive is scraped on the film, adhered to the base cloth, and after drying and solidifying, the release paper is peeled off by a peeling device, and the finished artificial leather and the release paper are respectively wound into a roll. Polyurethane paste coatings, release papers and base fabrics are three components of the dry process. The synthetic leather film produced by the dry method is dense, the product strength is excellent, the bonding is firm, and the wastewater produced by the process is less, but the hygienic performance of the product is relatively poor, and the exhaust gas generated in the production process is seriously polluted.
2 wet polyurethane synthetic leather
The wet method mainly penetrates the slurry into the gap of the nonwoven by extrusion, and then the nonwoven fabric is caused to be in the coagulation bath, and the DMF is continuously mixed from the resin solution into the coagulation bath by the "DMF-H2O" system. At the same time, the water enters the base fabric, and the PU gradually changes from the dissolved state to the gel state to form a solid film. In the exchange process, a large number of micropores are formed due to the adjustment of the auxiliary agent and the shrinkage of the polyurethane, and a multilayer structure having a continuous porous layer is obtained, so that the synthetic leather produced by the wet method has good moisture permeability and air permeability, and is soft to the touch. Full, light and rich in the style and appearance of natural leather.