The Effect of Neutralization Degree on Self Matting Waterborne Polyurethane

ABSTRACT This paper deals with the key factors in the synthesis of self‐matting waterborne polyurethane. A series of self‐matting waterborne polyurethanes (PTMG‐PUD) were successfully prepared by adjusting the neutralization degree and chain extenders. According to the infrared spectra of the prepolymer and PTMG‐PUD, the absorption peak of the NCO group (2297 cm −1 ) disappears, indicating that there is no isocyanate residue in the preparation of PTMG‐PUD, and the reaction has been complete. The analysis results indicate that when the neutralization degree of DMPA carboxyl groups decreases from 100 to 36.8 wt%, the particle size increases (from 0.351 to 1.028 μm) and the gloss decreases (from 48.6° to 0.6°) and all the film has high ultraviolet transmittance, reaching over 80%. The solid content of the emulsion has little effect on the gloss (the gloss is 6.7°–8.1°). When polyetheramine (PEA, Mn = 230) and isophorone diamine (IPDA) are used as chain extenders, they have different chain extension effects. After chain extension by IPDA, the gloss of the polyurethane emulsion film decreases (< 1°), and the tensile property is better (about 23.2 MPa, 662%). By exploring factors such as the neutralization degree and chain extenders, self‐matting waterborne polyurethane suitable for low‐gloss coatings can be prepared.