In 1940, German researchers discovered triphenylmethane-4. 4', _4'-triisocyanate can bind metal to sodium butadiene rubber and is used on tank tracks in World War II. Since the 1950s, Bayer has developed esmorhurs series (diisocyanate and polyisocyanate) and I esmophens series (low molecular weight hydroxyl-terminated polyester polyols). Polystal series products (two-component solvent-based polyurethane adhesives) can be prepared according to a certain amount of esmbd sweetness and esmopl~en.
Japan introduced German and American technology in 1954, produced polyurethane materials in 1960, and began to produce polyurethane adhesives in 1966. It successfully developed ethylene polyurethane waterborne adhesives and put them into industrial production in 1981. At present, the research and production of polyurethane adhesives in Japan is very active, and together with the United States and Western Europe, it has become a major producer and exporter of polyurethane.