The Preparation And Application Of Low Gloss Waterborne Polyurethane

Currently, the main methods of waterborne polyurethane matting coating is prepared byadding matting agent to WPU dispersions to get a variety of water-based polyurethanematting coating composites. However, adding matting agent brings defects such as coatingbrittleness increasing, flatting agent precipitation, decreased resistance to polishing. In recentyears, one-component waterborne polyurethane resin matting paint industry began to receiveattention. WPU matting resin does not use any matting agent, and has excellent kneadresistance, folding resistance and rubbing resistance, etc.This paper focuses on the shortcomings of SiO2blends modified waterbornepolyurethane (WPU) coating, according to the light extinction principle, andpoly(tetramethylene ether) glycol(PTMG), isophorone diisocyanate(IPDI) and dihydromethylpropionic acid(DMPA) as prereaction monomer, and2-[(2-aminoethyl)amino]ethanesulfonicacid sodium (A95), hydrazine hydrate as chain extender to prepare a series of low gloss WPUdispersions. The structure and properties of WPU were characterized by using FTIR, SEM,AFM, UV-vis, TG, etc. Studied the effect of chain extender, molecular weight of soft segment,the change of R, wDMPAand wA95on WPU films60°gloss, light transmittance, and surfacemicro structure. And applied to different types of leather coating scraper. The resultsinvestigate the adhesion resistance of the coating, rub resistance, folding resistance, fastnessand rubbing fastness. The main contents further summarized as follows:Firstly, the effects of prereaction temperature and time on WPU prepolymer was studied,determined prereaction first reacted at60℃for1.0h, then heated to80℃for2.0h. Theneutralization emulsification and chain-extend processes were screened briefly at the sametime. This paper used the front neutralization process and phase inversion emulsificationdispersion method to prepare WPU matting resin dispersions.FTIR analysed the structure ofWPU prepolymer and films, TG analysed a series of films thermal performance, themicrostructure on the surface of the films was characterized by SEM of. To further, test thelight transmittance and water absorption of films, for optimizing formula of reference.Second, with the single factor analysis method to study chain extender, soft segmentmolecular weight, R, wDMPAand wA95on WPU film60°gloss, light transmittance and surface microstructure, a series of stable emulsion and films with low gloss and regular microsphereswere obtained. The films are opacity. The results showed that a smaller molecular weight ofthe soft segment and hydrazine hydrate as chain extenders can obtain better microstructureWPU film; the gloss and light transmittance firstly decrease with R, then increase. With thewDMPAincreased, the gloss and light transmittance of the films keep unchange, after theinflection point2.8%, increase with wDMPA. WPU-A film gloss and light transmittanceincrease with the increase of wA95, the microsphere structure of surface gradually disappear.AFM results show that the WPU-R3film microscopic spherical surface roughness.Finally homemade WPU-R with WPU-D series formulated into extinction WPU scrapercoating, and applied to PVC and PU leather, contrast to PU980and WR-8072, examines thevarious adhesion resistance, knead resistance, folding resistance and rubbing resistance. Theresults show that, the proporties with GB above of WPU-R3are closest to PU980, is theoptimal product.