Waterborne polyurethane system, PET film coating, I want to improve the alcohol resistance of the coating, what is the best way? Tianshi produce waxes for waterborne polyurethane
1. Consider making a baking system.
2. The alcohol resistance is not enough because there are hydroxyl groups in the functional groups. In the reaction, the hydroxyl groups should be reacted as completely as possible. In addition, the molecular weight of polyols can be selected to be larger.
3. The choice of cross-linking agent is very important. By increasing the cross-linking density, the overall performance of the paint film can be improved. The crosslinking agent can refer to the following: amine alcohol chain extender; aziridine, which can react with carboxyl group, but easily causes the paint film to become brittle; silane; increase trifunctional monomer.
4. Add a curing agent with large molecular weight, such as TMP, but when TMP is used, the viscosity of the prepolymer will be too high, so it should be used with caution.
5. Add dispersant, but the choice of dispersant is also very important. Active dispersants help to aid alcohol, but common dispersants have an exacerbating effect.
6. The choice of resin is very important; in addition, the choice and ratio of two-component isocyanate are equally important.
7. Add maleic anhydride, maleic anhydride is a co-alcohol auxiliary, which is insoluble in alcohol and can improve the alcohol resistance of the paint film.
8. Test after 48 hours of printing and coating, because it takes time for cross-linking reaction.
9. Grafted polycaprolactone (partial), all performance levels are improved.
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