Polyurethane adhesive molecular chain containing amino acid ester group (-NHCOO-) or isocyanate group (-NCO), is divided into two categories of isocyanate and polyurethane. Through the system of isocyanate groups and the system or the system containing active hydrogen substances react, to produce polyurethane groups or polyurea, which makes system strength greatly improved and the adhesion to polyurethane adhesive.

  Adhesive is the main agent with adhesive, with a variety of curing agent, plasticizer, filler, solvent, preservative, stabilizer and coupling agent, such as the preparation of additives. In recent years, with the rapid increase in the level of the development of materials, a series of more applicable to the advent of adhesive, greatly enriched the adhesive market.

 Polyurethane adhesive is a high-grade adhesive with excellent flexibility, impact resistance, chemical resistance, abrasion resistance, the most important is its low-temperature resistance. By adjusting the raw materials and formulations can be designed for a variety of adhesive material between the many types of polyurethane adhesive variety of different uses. Polyurethane adhesive was first used in the military field in 1947 by the Bayer company triphenylmethane triisocyanate successfully applied to bond metal and rubber, to use the treads of tanks, laid the foundation for polyurethane adhesives industry. Japan introduced in 1954, German and American technology, in 1966 began producing polyurethane adhesives, the successful development of the ethylene-based water-based polyurethane adhesive, and put into industrial production in 1981. Currently, Japan's research and production of polyurethane adhesive is very active, and the United States, Western Europe together into polyurethane production, a major exporter. After the 1980s, the rapid development of polyurethane adhesive, is now a wide variety of industry-wide.

  China's development in 1956 and the production of triphenylmethane triisocyanate (Alekna gum), and soon production of toluene diisocyanate (TDI), a two-component solvent-based polyurethane adhesives, polyurethane adhesives has remained our largest output Variety. After that, China has successively introduced from abroad a number of advanced production lines and products, which needs to import large quantities of polyurethane adhesive and its facilities, thus promoting domestic research institutions to accelerate the development of polyurethane adhesives. Especially after 1986, China's polyurethane industry into rapid development period. In recent years, polyurethane rubber prices continue to decrease, the current price of only polyurethane glue about 20% higher than the neoprene, polyurethane rubber neoprene occupied market conditions.

 As an independent industry adhesive has a complete production chain, but also as a special auxiliary industry packaging industry plays an indispensable role in promoting behind the entire packaging industry in the production process, and technological progress as well as the packaging and related industries product development and has a major update profound impact. Therefore, the development and production of various types of more quality assurance, more superior performance of the new adhesive has naturally become the packaging industry has been more concerned about the field of study and research activities. This also contributed to the adhesive industry development and growth to a large extent on.

  Currently polyurethane adhesive is solvent-based, most of the domestic food packaging adhesive composite film used in the industry are solvent-based, so there is environmental pollution and safety issues, and a considerable amount of energy. It is estimated that only the food packaging industry emissions into the atmosphere of the organic solvent to more than 400,000 t per year. Flammable organic solvents, volatile, smell great, cause air pollution when used, more or less toxic. Solvent solvent-based adhesives in the production process emissions will not only pollute the air, directly endanger the health of workers in the operation, but eventually there will be a small portion of the solvent can not be excluded, the residual harm the health of consumers in food packaging. This is more terrible than the food itself is a security risk. Currently, the function and application of adhesives has been widespread attention, while the adhesive environmental issues are often easy to be ignored. Are environmental protection has become a bottleneck for further development of adhesive, to solve their problem of pollution of the environment has become a priority.

  In recent years, China's demand the fastest growing hot melt adhesive without using an organic solvent, and rapid construction, good bonding effect, the development prospects are very impressive. In addition to traditional EVA hot melt, the market should actively develop polyester, polyamide hot melt adhesive new varieties. At present, foreign companies in China's production of low formaldehyde emission urea-formaldehyde glue, while supporting the establishment of large-scale timber processing plants. Currently a large number of foreign countries are referred to using environmentally friendly solvent-free adhesives in the true sense. Without solvent means a solvent-free adhesives, because no solvent evaporation to the atmosphere, will not cause pollution and harm. Solvent-free polyurethane adhesive for all types of composite plastic packaging, aluminum foil also has a good bonding effect, content resistance and high-temperature cooking performance with the same ester solvent polyurethane adhesive, and high peel strength. Water-based adhesive is non-flammable, non-toxic, no pollution, product adaptability and favored. But the inadequacy of water-based adhesive is slow drying, poor water resistance, frost is not good, high cost and energy consumption in the next 10 years can not completely replace the ester solvent polyurethane adhesive. Therefore, in the future development of the production process should be increased in the solid part of the water-based adhesives, and speed up the drying speed, the use of cross-linking methods to improve the drying speed and water resistance, in order to expand its range of applications and market share.
 Increasing human awareness of environmental protection, increasingly stringent laws and regulations, and therefore promote the use of environmentally friendly adhesive is an inevitable trend. Reactive polyurethane hot melt adhesives and adhesion due to sizing process defects, not suitable for our industry, cost-efficient production methods; the process conditions used in aqueous polyurethane adhesive, solvent rubber adhesive properties and is basically the same, it will be in the future direction of development, but there are still due to the current high prices, the application of process control is not mature enough, the passing rate is lower than the adhesive glue and other solvents, and therefore largely replaced solvent-based polyurethane adhesive in an aqueous polyurethane glue the next 2 to 3 years is unlikely, this period will remain low contains "BTX" solvent adhesives market. The next few years, China will vigorously develop research and development of high-tech, high value-added, high-performance adhesive new products, such as waterborne polyurethane adhesives, water-based chloroprene rubber-based adhesives, pressure-sensitive and high-performance and high-quality products, VAE (vinyl acetate - ethylene) emulsion, EVA (ethylene - vinyl acetate) resin, SIS (styrene - isoprene - styrene) resin, but also will focus on the development of environmentally friendly, energy-saving adhesives to follow development of the market and the law of human existence.