In recent years, with the rapid improvement of material research and development, various adhesives with stronger applicability have come out one after another, greatly enriching the adhesive market. Polyurethane adhesive is a medium-to-high-grade adhesive with excellent flexibility, impact resistance, chemical resistance, abrasion resistance, and most importantly, its low temperature resistance. By adjusting the raw materials and formulas, multiple types of polyurethane adhesives suitable for bonding between various materials and for various purposes can be designed.
Polyurethane adhesives were first used in the military field in 1947. Bayer successfully applied triphenylmethane triisocyanate to the bonding of metal and rubber and used it on the tracks of tanks, laying the foundation for the polyurethane adhesive industry. Japan introduced German and American technology in 1954, produced polyurethane materials in 1960, and began producing polyurethane adhesives in 1966. It successfully developed vinyl polyurethane water-based adhesives and put them into industrial production in 1981. At present, the research and production of polyurethane adhesives in Japan are very active, and together with the United States and Western Europe, Japan has become a major producer and exporter of polyurethane. After the 1980s, polyurethane adhesives have developed rapidly and have now become an industry with a wide variety of applications.
my country developed and produced triphenylmethane triisocyanate (Lekna glue) in 1956, and soon produced toluene diisocyanate (TDI) and two-component solvent-based polyurethane adhesives. It is still the largest producer of polyurethane adhesives in my country. Variety. After that, my country successively introduced many advanced production lines and products from abroad, which required a large amount of imported polyurethane adhesives to support them, thus promoting domestic research units to accelerate the development of polyurethane adhesives. Especially after 1986, my country’s polyurethane industry entered a period of rapid development. For a long time, the price of polyurethane glue in my country has been too high. For a long time, the price of polyurethane glue was 1 to 2 times that of neoprene. The price of polyurethane glue has been continuously decreasing in recent years. The current price of polyurethane glue is only about 20% higher than that of chloroprene rubber, which provides conditions for polyurethane glue to occupy the chloroprene rubber market.
The production methods of polyurethane glue include solution method and solid resin dissolution method. At present, there are more than 100 companies producing polyurethane glue for shoes in mainland my country, including more than 20 large-scale companies. The production capacity of Nanguang, Bali and other companies is more than 10,000 tons/grade. Basically, they use Spanish, Germany, the United States and Taiwan import resin for dissolution to produce polyurethane glue. In view of the large number of manufacturing companies and increasingly fierce competition, in order to have technical and price advantages, some large adhesive factories have begun to build solution-based polyurethane glue production equipment. Therefore, the proportion of solution-based polyurethane glue production will decrease.
The most common polyurethane glues currently are solvent-based. Like neoprene, there are problems of toxicity and environmental pollution. In recent years, “triphenyl”-free polyurethane glue has appeared one after another, that is, using mixed solvents such as ketones and esters. The toxicity has been reduced, but the problem has not been fundamentally solved.
Polyurethane adhesives are classified according to their reaction composition and can be divided into polyisocyanate adhesives, isocyanate group-containing polyurethane adhesives, hydroxyl-containing polyurethane adhesives and polyurethane resin adhesives. According to their uses and characteristics, they can be divided into general-purpose adhesives, food packaging adhesives, shoe adhesives, paper-plastic composite adhesives, construction adhesives, structural adhesives, ultra-low temperature adhesives, foaming adhesives, and anaerobic adhesives. Conductive adhesives, hot melt adhesives, pressure sensitive adhesives, sealed adhesives, water-based adhesives and sealing adhesives, etc.
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