Polyurethane coating is a kind of coating technology which began to rise in the 1960s. In view of the increasingly strict requirements of environmental protection laws and regulations, the environmentally friendly water dispersive polyisocyanate has shown its importance in various application fields in recent years. Although polyether modified polyisocyanates are widely used, they all have one basic disadvantage, especially when they are used as crosslinking agent of waterborne two-component polyurethane coating, higher polyether content is needed to ensure sufficient dispersion, which leads to a long drying time and long-lasting hydrophilicity of the coating. These shortcomings have been solved on the CAPS (3-(cyclohexylamine)- 1-propanesulfonic acid) modified polyisocyanate.
CAPS (an amphoteric sulfamate) reacts with aliphatic polyisocyanate under mild conditions and in the presence of tertiary amine neutralizer. The sulfonylurea derivative is an excellent emulsifier. Without considering the influence of salt forming group, CAPS modified polyisocyanate has very good storage stability and the finished product is not turbid. Even if it contains less sulfonate groups, it can also be in water The emulsion with good dispersing state was obtained. Thus, a series of ionic modified polyisocyanates can be obtained, which can be used in various environment-friendly high-quality two-component polyurethane coatings. These coatings are completely superior to general solvent based coatings in terms of dryness, curing and chemical resistance. With the requirements of new regulations, VOC (volatile organic compounds) content in decoration materials is further reduced, which makes the amount of these cross-linking agents increase greatly. Compared with solvent based coatings, they will not lead to the degradation of film quality. CAPS modified polyisocyanate has been widely used in automobile original paint, repair paint, plastic paint, wood paint, fabric leather paint, printing ink industry, etc. with its excellent performance. The market prospect is self-evident.
Preparation of CAPS modified polyisocyanate
950g polyisocyanate was stirred with 50g CAPS, 29g dimethylcyclohexylamine and 257g 1-methoxypropyl-2-yl acetate under dry nitrogen for 5 hours at 80 ℃, wherein the polyisocyanate is based on hexamethylene diisocyanate (HDI) and contains isocyanurate group, NCO content is 21.7%, average NCO function is 3.5, monomer HDI content is 0.1% and viscosity is 3000mpas. After cooling to room temperature, colorless and transparent polyisocyanate solution can be obtained.
CAPS produced by Desheng company has not only been widely used in the new paint market, but also in the field of biochemical industry. Because it is also a biological buffer, it is widely used in biochemical diagnostic kits, DNA/RNA extraction kits and PCR diagnostic kits. Welcome enterprises and individuals to call for turther consultation.
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