Current situation and future of the hottest polyur

2022-07-24
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The current situation and future of polyurethane in the world (Part 2)

in recent years, the research on liquid crystalline polyurethane in the world is quite active, mainly focusing on the selection of raw materials, the optimization of process routes and the improvement of physical properties. Liquid crystalline polyurethane (LCPU) is a kind of polyurethane elastomer with liquid crystalline properties in the solution state, which is connected by rigid mesogenic gene and flexible spacer group. The material has good mechanical, thermal stability, high elasticity, high elongation and good processability. The synthesis of liquid crystalline polyurethane elastomers is processed by one-step or two-step polymerization. The processes are diverse, including extrusion, injection molding and coating. Marubeni and koatsu cloth, a synthetic leather manufacturer, jointly industrialized the production of water-based polyurethane resin

it is said that the synthetic leather produced from this raw material has the properties of uniform density and excellent strength, and can reduce the energy consumption in the production process. Ordinary polyurethane synthetic leather is a solvent type, which is potentially harmful to human body and the environment. Coating it on fabric to produce synthetic leather requires a polymerization process and consumes a lot of energy. The above products developed by the two companies can be used in clothing, footwear, household goods, furniture and automobile transportation equipment. Shanghai Xiangxiong Technology Co., Ltd. has also developed a kind of waterborne polyurethane resin. This product has excellent yellowing stability, water resistance and adhesion, and is suitable for the processing of various fibers. Various water-based resins can be diluted and compatible with it in any proportion. It can be used as a paste for painting and printing. It can be added to water-based coatings to prevent cracking of the coating, increase luster and lubrication, and be used as a brightener, rainproof cloth, umbrella coating of leather and PU leather

the production of environmentally friendly products is an integral part of the cleaner production environment. European technology companies have successfully developed non isocyanate polyurethane (Nipu) for coatings and alternative epoxy polyurethane. It is not produced from harmful isocyanate precursors. The use of isocyanate polyurethane has adverse effects on the environment, while Nipu does not contain harmful substances. Not only can the energy density of the battery be improved, Nipu has better mechanical properties and chemical resistance than conventional polyurethane. Nipu is produced from crosslinked cyclic carbonates and amine oligomers. The first 50 ton/year unit was built in Israel in 2001

poly amino acids of automobile and household electrical appliances have also been widely used in other fields. The recycling of waste foamed plastics has attracted more and more attention. Foreign automobile manufacturers have proposed to use 30% recycled waste foams before 2002. Argonne National Laboratory and its partners in the United States have successfully developed a low-cost recycling technology and built a set of test devices. The production process is to first remove the metal impurities in the automobile garbage, then clean, crush and dry the waste foamed plastics, and finally stick these waste foamed plastics together with adhesives, which can be used to produce carpet cushions and other cushion materials. It is estimated that an investment of 700000 US dollars will be required to build a factory with an annual production capacity of 1000 tons, taking full account of the product performance requirements. It is estimated that the total investment can be recovered within two years. Toshiba has developed a continuous chemical recovery method (chemical decomposition method) for polyurethane foam, a refrigerator insulation material. Using an extruder with three functions of compression, heating and mixing, the waste polyurethane resin crushed into 5mm size is decomposed into a part of oligomer with carbamate bond and polyol as the main oligomer with ethylene glycol amine as the decomposition agent

when the decomposed product is mixed with fresh polyols and Isocyanates (the decomposed product accounts for about 20%), recycled polyurethane foam with good performance can be produced. The complete recovery process can be used for continuous production without waste. The technology has been developed to practical use. The equipment uses an extruder that continuously compresses, mixes and heats up with the help of the rotation of the screw, and injects diethanolamine to continuously decompose the waste polyurethane, so that the decomposed product can be obtained at a high speed. When the mixing ratio of polyurethane resin is more than 80%, the intermittent method takes 45 minutes, while the continuous method only takes 3 minutes to decompose. The decomposed product is transparent and its viscosity is much lower than that of the batch method

according to the analysis, 68% of the decomposed products are oligomers containing carbamate gene, and another 28% are oligomers with polyether polyols as the main body. For the regeneration of polyurethane resin, pure polyols and isocyanates were added to the oligomer decomposition products, and the polyurethane resin was prepared by high-speed stirring. When the mixing ratio is 20% lower, it becomes a foam with higher strength than pure materials. The characteristic of this regeneration process is that, in addition to high-speed continuous treatment, no by-products are produced and no separation and refining of decomposition products are required due to decomposition into the polymer

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