Common synthetic methods of PU steel wire hose and polyurethane hose material and their use analysis
The main products of polyether glycol commonly used in the synthesis of polyurethane hoses are: polyethylene oxide (polyethylene glycol) glycol (PEG), polypropylene oxide (polypropylene glycol) glycol (polypropylene) Glycol, PPG), polytetramethylene glycol (PTMEG), and homo- or copolymerized glycols or polyols of the above monomers. Among them, PPG has a large output and a wide range of uses. The comprehensive performance of PTMEG is better than that of PPG. PTMEG is composed of cationic initiators. Initiated ring-opening polymerization of tetrahydrofuran monomer, and its output has increased rapidly in recent years. There are also domestic manufacturers such as Shenzhen Hangzhou Haikuo hose.
Polyether waterborne polyurethane has good low-temperature flexibility, hydrolysis resistance, and low price, but its oxidation resistance and UV resistance are poor, and its strength and hardness are low. It is a low-end product.
Polyurethane aqueous dispersions prepared by polyester polyols have higher crystallinity, which is beneficial to increase the strength of the coating film, but their hydrolysis resistance is often not as good as polyether products. Different types of polyester polyols have hydrolysis resistance stability A big difference. The higher the relative molecular mass of the polyol, the more the amount used, the lower the surface hardness, the greater the elongation, and the lower the strength. Changing the types and proportions of synthetic monomers can be made into a series of polyurethane hoses with different hardness and softness, and PU steel wire hoses are suitable for the needs of food-grade hoses and industrial vacuum equipment.
Polyester polyols theoretically have unlimited varieties. At present, the more commonly used ones are: polyethylene adipate diol, poly-1,4-butanediol adipate diol, polyhexylene adipate diol, etc.; domestic production of polyester There are many manufacturers, but the annual production capacity is mostly below 1000t. It consists of 2-methyl-1,3-propanediol (MPD), neopentyl glycol (NPG), 2,2,4-trimethyl-1,3-pentanediol (TMPD), 2-ethyl-2 -Butyl-1,3-propanediol (BEPD), 1,4-cyclohexanedimethanol (1,4-CHDM), adipic acid, hexahydrophthalic anhydride (HHPA), 1,4-ring Hexanedicarboxylic acid (1,4-CHDA), azelaic acid (AZA), isophthalic acid (IPA)-derived polyester diols have greatly improved hydrolysis resistance, which can improve the storage stability of polyester-based waterborne polyurethanes. It is supported by raw materials, but its price is more expensive. At present, hydrolysis-resistant polyester diols for waterborne polyurethanes are mainly imported products, and relevant domestic enterprises should increase the research and development of such products to meet the development of the waterborne polyurethane industry. In addition, the homocondensation polymer polycaprolactone diol (PCL) and polycarbonate diol can be used in the synthesis of polyurethane.
Polyurethane can be classified from many angles. It has a wide range of uses and excellent performance. Different monomers and different processes can be used to synthesize polyurethane hoses with different performances and various apparent forms. There are soft and hard foam plastics, wear-resistant rubber, high-elastic synthetic fibers, synthetic leather with excellent flexural resistance, and adhesives with good bonding properties. In the field of coating resin, polyurethane resin is also a representative of high performance. The polyurethane formed by it constitutes a series of products and has very important applications. Polyurethane resins for coatings are generally divided into resins for one-component polyurethane coatings and resins for two-component polyurethane coatings.