Introduction to Polyurethane
Polyurethaneis a multifunctional and multi-purpose synthetic polymer material, which isusually prepared by the reaction of oligomer polyols, polyisocyanates and chainextenders/crosslinkers. Its products cover foams, synthetic rubbers, plastics,synthetic fibers, Coatings, adhesives and many other synthetic materialsfields, such as rigid foam insulation materials, soft foam cushioningmaterials, elastomer parts, microporous elastomer shoe materials, high elasticfibers, fabric and leather coatings, paint coatings, adhesives , sealant andpotting glue, waterproof and protective coatings, imitation wood materials,treatment agents and other products are used in cold chain, transportation,construction, home furnishing, clothing and shoe leather, machineryaccessories, food, packaging and printing, sports equipment, defense andmilitary And so on in all walks of life, this is unmatched by polymer syntheticmaterials such as polyethylene, polypropylene, polystyrene, polyvinyl chloride,polyacrylate, etc
In 1937,Otto Bayer of Germany discovered the industrial application value ofpolyurethane. From 1941 to 1942, the German Bayer company established apolyurethane factory with a capacity of 1,200 tons per year. The initialpolyurethane production technology was developed and started in Europe and the United States. development, while gradually spreading to other countries andregions. From the perspective of changes in the global output of polyurethaneproducts, in 1956, it was only more than 3,600 tons, and by 1967, it had grownto more than 270,000 tons. In 1983, the global output of polyurethane productswas about 3.8 million tons. , more than 8.6 million tons in 2000, about 16.69 milliontons of global polyurethane production in 2010, about 18.96 million tons in2012, and about 23.07 million tons in 2018. At present, the growth ofpolyurethane is stable, and the global polyurethane production is expected toexceed 25.7 million tons by 2022. In the next few years (2019-2022), it is expected that the overall global polyurethane consumption will maintain anupward trend year by year, with an average annual growth rate of around 6.7%.
My country's polyurethane industry started in the late 1950s and developed slowly. The annual output in the late 1960s was estimated at about 1,000 tons. Before1978, the national output of polyurethane products was only about 5,000 tonsper year. With the introduction and construction of raw material devices suchas isocyanate MDI, China's polyurethane industry has begun to accelerate itsdevelopment. In 1989, the output of polyurethane raw materials in my countryreached 32,200 tons, and the output of products reached 99,300 tons (someproducts such as coatings and adhesives, the estimated output value containssolvents, the same below), accounting for only 2.34% of the total globalproduction and sales of 4.25 million tons. %. After the 1990s, with theintroduction and operation of large-scale isocyanate and polyether units of 10,000 tons, China's polyurethane industry has entered a stage of rapiddevelopment. In 1998, the total amount of polyurethane products was about770,000 tons, and in 2000, it was 922,000 tons. In 2010, the consumption ofpolyurethane products in my country increased to 6.5 million tons, and in 2014,it increased to 9.6 million tons.
In 2018,the consumption of polyurethane reached 12.5 million tons (including about 39% of polyurethane foam, about 17% of synthetic leather resin slurry, about 5% ofsole solution, about 16% of polyurethane coating, about 10% of elastomer, andabout 10% of polyurethane adhesive. Sealant about 6%, spandex about 6%).
The totalproduction and consumption of polyurethane in my country has exceeded that of European and American countries, but the per capita consumption is far lower than thatof developed countries. However, my country's polyurethane industry isdeveloping rapidly at present, and the growth rate is always higher than thatof GDP.
Application fields and development prospects of elastic polyurethane materials
Polyurethaneelastic materials belong to block polymers, that is, polyurethanemacromolecules are composed of "soft segments" and "hardsegments" and form a microscopic phase separation structure, in which thehard segments (derived from isocyanates and chain extenders) are dispersed inthe soft segment phase region ( It is derived from oligomer polyol) and playsthe role of physical cross-linking point. Therefore, compared with othersynthetic rubbers (elastomers), polyurethane elastomers have better strengthand wear resistance, and can maintain high elongation even when the hardness is high. length.
Elasticpolyurethane materials, referred to as "CASE" abroad, mainly includetraditional polyurethane elastomer products, paving materials such aspolyurethane plastic runways, polyurethane waterproof coatings, adhesives,sealants, potting glues, etc., accounting for about 30% of the totalpolyurethane products. About 40%, the cured product of the vast majority ofCASE materials (water and solvent-based products after removal of water andsolvent) is a non-foamed elastic polyurethane material. Among them, PUsynthetic leather resin, some coatings and adhesives are solvent-based or water-basedproducts, which can also be considered as polyurethane elastomer materials in abroad sense. Polyurethane elastomers in a narrow sense refer to castingpolyurethane elastomers (CPU), thermoplastic polyurethane elastomers (TPU) andmixing polyurethane elastomers (MPU), accounting for 10% or slightly less ofthe total polyurethane, of which CPU and TPU are The main polyurethaneelastomers, they are differentiated by factors such as production process andchain extender. This kind of traditional polyurethane elastomer is also called"polyurethane rubber", which belongs to a kind of special syntheticrubber. High-performance polyurethane elastomer is the material with the bestwear resistance among all synthetic polymer materials. It is widely used in manyfields, and new applications are still expanding.
Polyurethaneelastomers can be used to replace metals, plastics and ordinary rubber in somefields.
Comparedwith metal materials, polyurethane elastomers have the advantages of lightweight, low noise, wear resistance, low processing costs and acid corrosionresistance. Compared with plastics, it has the advantages of high toughness andhigh wear resistance. Compared with general rubber, polyurethane elastomer hasthe advantages of wear resistance, cutting resistance, tear resistance, highbearing capacity, ozone resistance, etc., and is simple to manufacture, can bepotted, poured, and has a wide range of hardness.