Under the driving force of environmental protection, health and safety, polyurethane adhesives, like other adhesives, are developing in the direction of environmentally friendly high performance such as solvent-free, water-based and reactive hot-melt, to gradually replace the high-grade and poisonous categories of VOCs. However, solvent-based polyurethane adhesives still have some properties that are superior to other categories, so they continue to be adopted in some areas.
For example, in the shoe-making industry, solvent-based polyurethane adhesives have a high bonding strength to leather and other shoe materials, and the durability of their adhesive components is strong. In the dry film process, solvent-based polyurethane adhesives wet the film. Okay, so it has so far been widely adopted. Use more in developing countries. However, the solvent used must be low in toxicity, low in air pollution, and equipped with a recovery device; the adhesive must have a high solid mass fraction to reduce the escape of toxic solvents into the air. The curing agent for two-component polyurethane adhesives is mostly polyisocyanate with a free isocyanate content of less than 0.5%.
In Europe, the United States, Japan and other developed countries or regions, the use of solvent-based polyurethane adhesive in the field of dry compounding more than 60%. Since 1980, China has begun to introduce Japanese composite film production technology and equipment. It is estimated that the dry film production line is now over 300, and the polyurethane adhesive is used over 35,000 tons per year. The solvent-based two-component polyurethane adhesive that was first applied to the composite packaging industry in China was produced by the Beijing Chemical Industry Research Institute in 1984 from the former West Germany. The main product is a low viscosity, high solids (75%) polyurethane adhesive. Since then, various types of domestic composite equipment have entered the market, and domestic manufacturers and research institutes have successively developed a variety of compatible solvent-based two-component polyurethane adhesives, mainly low solids (15% to 50%), high-viscosity products.
Source: China Adhesive Network
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