With the development of the times, people pay more attention to the quality of life, home is a warm and comfortable place for everyone to enjoy, but many decoration companies in order to save costs in the choice of paint is not satisfactory.Therefore, in response to increasingly stringent environmental regulations, water-dispersible polyisocyanates have shown importance in various applications in recent years.At present, water-dispersible polyisocyanates in most applications are non-ionic hydrophilic modification by polyethers.Although this hydrophilic modified polyisocyanate has gained wide market recognition in most applications, it also has certain drawbacks, such as its high viscosity, which requires a considerable shear force to be applied in the construction process to uniformly introduce it into the aqueous medium.In order to avoid these shortcomings, this also gives CAPS an excellent opportunity.Let it find its location in new coatings.
CAPS in Packaging
Ion-modified groups include carboxyl group, sulfuric acid group, hydroxyl group, hydroxy sulfonic acid, etc., but there are still some defects, such as carboxyl-modified polymers are prone to gelation, hydroxy sulfonic acid-modified products are obviously yellow in color, etc.Later, Bayer reported 3-(cyclohexylamino)-propanesulfonic acid (CAPS)-modified polyisocyanate in its patent CN1429240A. The study found that CAPS-modified polyisocyanate could be finely dispersed in water and the product was stable in storage.CAPS-modified polyisocyanate exhibits certain advantages over other ionic or non-ionic modified products.
1. 3-(cyclohexylamino)-1-propane sulfonic acid (CAPS) reacts with aliphatic polyisocyanates (the former is a zwitterionic aminosulfonate) under mild conditions and in the presence of tertiary amine neutralizers, and the resulting urea sulfonate derivatives are excellent emulsifiers.Regardless of salt forming groups, CAPS-modified polyisocyanates have good storage stability and are not turbid. Even if they contain fewer sulfonate groups, they can get well dispersed emulsions in water.A series of ionized modified polyisocyanates can be obtained for use in various environmentally friendly high quality waterborne two-component polyurethane coatings.These coatings are comparable to general solvent-based coatings in terms of dry, curing and chemical resistance.The new regulations require further reduction of VOC (volatile organic compounds), and the use of these crosslinkers will definitely increase in the future. Compared with solvent-based coatings, they will not lead to a decrease in paint film quality.
2. Closed water-dispersible polyisocyanate curing agent: Closed water-dispersible polyisocyanate curing agent is a kind of closed polyisocyanate curing agent that is hydrophilically modified so that such products can be dispersed in aqueous resin system.Under the condition of high temperature baking, the blocking agent will be unblocked from the system, releasing isocyanate groups, which react with hydroxyl groups.
3. Closed water dispersible polyisocyanate curing agent is mainly used as crosslinking agent in high temperature baking system.At present, the main use is in the Mid-coating of automobile original paint, in addition, there are also some applications in water-based industrial paint.Closed water dispersible polyisocyanate curing agent can also be used with melamine curing agent to reduce costs,and closed water dispersible polyisocyanate curing agent to improve performance.
CAPS is used as a biological buffer in addition to new materials and coatings, in biochemical diagnostic kits, DNA/RNA extraction kits and PCR diagnostic kits, and in buffer solutions for enzymatic chemistry and HPLC separation of alkaline drugs.
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