Are waterborne polyurethane and polyurethane used for the same purpose?

Are water-based polyurethane and polyurethane the same? Today, ZHEJIANG RUICO ADVANCED MATERIALS CO., LTD. will briefly explain to you. I believe you are not familiar with water-based polyurethane and polyurethane, but are their uses really the same? Waterborne polyurethane should be classified into polyurethane, and polyurethane materials are widely used, from fiber products, elastomer products, coatings, etc.; waterborne polyurethane is usually used for some elastomer applications, such as gloves, and some high-end coating applications.





Water-based polyurethane belongs to one of the polyurethanes. Due to the different uses of the formula, there are many coatings that are now manufactured, and can also be used as adhesives, elastomers and so on. 

Polyurethane has many advantages, so it is widely used in: coatings, inks, adhesives, leather finishing agents, artificial leather, gloves lubricants, etc. Take leather finishes as an example: Finishing is an important part of the leather manufacturing process. It can increase the beauty and durability of leather, improve the grade, increase the variety of colors, and expand the scope of use. Among them, the polyurethane coating agent has good film-forming performance, strong covering power, firm bonding, and excellent physical properties of the coating, which can greatly improve the grade of finished leather, which has been highly valued and widely concerned.

At present, most water-based PU is mainly prepared by self-emulsifying method, with PU containing hydrophilic group as the main curing component. Water swells easily. In addition, it lacks the cross-linking density and high relative molecular mass that can be obtained by two-component solvent-based PU coatings, so the water resistance, solvent resistance, heat resistance and gloss of these water dispersion coatings are poor, serious limits its scope of use.

Therefore, it is often used to increase the crosslinking density of the coating film to improve the water resistance of the emulsion coating film. There are two commonly used cross-linking methods: one is to add polyhydroxy compounds with a functionality greater than 2 when synthesizing PU prepolymers to directly generate cross-linked PU prepolymers, which are well dispersed in water. , and chain extension to form macromolecules, and finally form an emulsion. This method is also called pre-crosslinking method. The disadvantage is that it is easy to increase the viscosity of the prepolymer, and it is difficult to disperse in water, which affects the stability of the emulsion.

In recent years, the research on the screening and synthesis of new crosslinking agents and multifunctional chain extenders has been quite active, and has become one of the main ways to improve the physical and mechanical properties and water resistance of water-based PU. Another method is the cross-linking method, which uses an anionic PU emulsion with carboxyl for cross-linking. The cross-linking reaction occurs on the carboxyl group of the PU molecule, including aziridine, carbodiimide and metal salt compounds, which are carried out at room temperature. cross-linked. This type of cross-linking agent is generally added when using PU emulsion, because the cross-linking reaction rate is very fast, and the gel is formed in a short time to break the emulsion. The cross-linking method can successfully solve the hydrophilic problem of the PU emulsion coating film, but due to the addition of a cross-linking agent, the composition of a two-component coating agent brings inconvenience to the construction, and this method is rarely used.