Soft packaging, also known as soft cans, is a unique combination of lightweight, easy-to-use, long shelf life, hygiene, easy storage and transportation, easy disassembly, low waste, and good shelf life. It has now surpassed hard packaging such as plastics and glass bottles. Cans and other polyurethane adhesive due to its excellent performance, can be different film materials bonded together to get cold, oil, drug resistance, transparency, wear resistance and other properties of flexible packaging composite film. At present, in domestic and foreign markets, polyamine ME3 adhesives have become the main adhesive for the processing of composite films for flexible packaging. In the domestic adhesive market, in the manufacturing of composite film for packaging, the amount of polyaminous M9 adhesive is second only to the footwear industry. A wide variety of polyurethane adhesives for packaging, such as water-based polyurethane adhesive M, hot-melt polyurethane adhesive E18 [353, solvent-based polyurethane adhesive m [, solvent-free polyurethane adhesive. The commonly used polyurethane hot melt adhesive can be divided into 2 categories: 1) thermoplastic polyurethane elastomer hot melt adhesive; (2) reaction T hot melt adhesive. The main disadvantage of plastic hot melt adhesives is their high viscosity, which has a great influence on the apparent quality of the coating. The reactive polyurethane hot melt adhesive is a new type of adhesive developed on the basis of traditional hot melt adhesives. It not only has the characteristics of good initial adhesion and excellent post-curing performance of traditional hot melt adhesives, but also has the composition of polyurethane E79. The versatility and wide range of performance adjustments provide excellent adhesion to a wide variety of substrates. In addition, the use of emulsifiers or the introduction of hydrophilic ionic groups in the molecule in the packaging of aqueous polyurethane I8 gels has reduced water resistance. In recent years, research on improving the water resistance has become a hot topic. At the same time, due to the large heat capacity of water, how to increase its solid content and increase its drying rate is also a problem to be solved at present.
