Application of waterborne polyurethane adhesive for printing
The most important application indexes of water-based adhesives in the packaging and printing industry mainly include four aspects: bonding strength, high/low temperature resistance, moisture resistance and viscosity holding.In practical application, defects such as weak adhesion and brittle degumming film are basically caused by the above four application indicators are not up to standard.In practical application, defects such as weak adhesion and brittle degumming film are basically caused by the above four application indicators are not up to standard.When choosing water-based adhesive, quality first and price second should be the principle. However, some packaging and printing enterprises have a one-sided view, mistakenly thinking that the higher the price of water-based adhesive, the better the quality; The other way around, the worse the quality actually, it's not absolute.When choosing water-based adhesives, we should first understand the characteristics of processed products and choose adhesives with higher cost performance, which is a reasonable way to choose and buy. The solid content of modified waterborne polyurethane adhesive sold in the market is generally 15%-35%, which increases the cost of transportation and drying, and affects the bonding property.So how to improve the solid content has become a hot research topic at home and abroad.At present, sulfonates are mainly used as hydrophilic chain extenders in the synthesis of water-based polyurethane with high solid content, and carbonates and carboxylate are also used as hydrophilic chain extenders.By introducing the ionic group (-COOH) to the end of the molecular chain through molecular design, stable waterborne polyurethane with low ionic group content and high solid content is prepared, which also provides a new idea for the development of waterborne polyurethane with high solid content.UV curing modified waterborne polyurethane adhesive with water as diluent, non-flammable environmental protection; And does not contain dilute monomer, is conducive to improve the adhesion of the film to the substrate.So get vigorous development in recent years Natural polymer modified waterborne polyurethane modified, such as nano cellulose fiber is one of the most abundant natural polymer materials in the nature, and nanometer fiber has higher strength of the modified waterborne polyurethane can not only reduce the cost, but also can obtain very good mechanical properties. With economic development, China's annual use of adhesives up to 600,000 tons, more than 90% of solvent-based adhesives, such adhesives contain a lot of toluene xylene butanone acetone ethyl acetate alkane and other organic solvents, the amount of glue accounted for 80% or more of the total weight.These organic solvents have certain toxicity, and some inferior adhesives are even produced with benzene, which is more toxic.These organic solvents have a certain toxicity, some inferior adhesives even use benzene to produce, its mo...
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