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Synthesis of Waterborne Polyurethane-acrylate Composite Emulsion for High-quality Wood Coating

Author: LiuTianLiang
Tutor: ShenHuiFang
School: South China University of Technology
Course: Chemical Engineering
Keywords: Aliphatic polyurethane - acrylate Anti-yellowing The PolyTHF ether diol Wood coatings
CLC: TQ630.4
Type: Master's thesis
Year: 2010
Downloads: 363
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Abstract

With the enhanced awareness of environmental protection and international, increasingly stringent domestic environmental regulations and improve the paint to the development of low pollution, high-performance direction. Wood coatings is closely linked with people's lives, a direct impact on people's health and living standards, water-based coatings has become a hot topic. Water-based polyurethane acrylate (PUA) with its excellent performance and become an important research direction of the high-grade wood coatings. Domestic TDI (toluene diisocyanate) polyurethane waterborne coatings studied more, and TDI polyurethane wood coatings easy to yellowing, does not apply to the requirements of high-grade wood coatings for anti-yellowing, this study developed for high-end wood coatings high-performance aliphatic PUA emulsion. Isophorone diisocyanate (IPDI) and a polyether diol N220, tetrahydrofuran, polyethylene ether glycol (PTMEG) as the basic raw material, the gradual addition polymerization, trimethylol propane (TMP) as cross-linking agent 1,4 - butanediol (BDO) chain extender and, after the introduction of dimethylol propionic acid (DMPA) a hydrophilic group, and then neutralized by triethylamine (TEA), polyurethane prepolymer. The polyurethane prepolymer to high shear dispersing in water, and ethylenediamine (EDA) chain extender to give the polyurethane (PU) dispersions. Methyl methacrylate (MMA) is pre-dispersed in the polyurethane dispersion, and azobis-isobutyronitrile (AIBN) as initiator to initiate polymerization to obtain the PUA composite emulsion. First study to polyether alcohol N220, poly tetrahydrofuran ether diol and polycarbonate diol the polyol used alone, or in a different proportion of compound used to synthesize a series of PUA hybrid emulsion, more detailed series of emulsion and the performance of the coating were compared, and ultimately determine alternative to PTMEG 50% N220 is the best option. The PTMEG and N220 50:50 compound used under the conditions studied the prepolymerized temperature, the organic solvent was added amount of the emulsion polymerization temperature, -NCO/-OH molar ratio, the amount of trimethylol propane crosslinking agent. The DMPA hydrophilic chain extender amount of shear emulsification process factors such as polyurethane aqueous dispersion and its performance, to determine the synthesis of PUA hybrid emulsion process and formula. Prepolymerized initial temperature of between 60 ° C ~ 65 ° C, post-heat temperature at 75 ° C or about; prepolymerized time 7.5H; 15% of the amount of organic solvent added; First NCO / OH molar ratio of from 10.5 to 11.0; -NCO/-OH molar ratio of 1.35; TMP amount of 2.0%; dispersion temperature of 20 ° C to -30 ° C; direct dispersion method the, after neutralization process impeller speed 4000-5000r/min; the PUA emulsion polymerization temperature of 70 ° C -75 ° C; MMA added amount 20% -30%. The use of modern analytical testing methods such as infrared spectroscopy, gel permeation chromatography, scanning electron microscopy, differential scanning calorimetry (DSC), were characterized by the PUA emulsion. The infrared spectra showed-NCO and-OH groups are very good involved in the reaction, to generate a carbamate group; gel permeation chromatography trace analysis showed that the synthesis process, PU molecular weight increases mainly in the amine-extended chain stage, the molecular weight of the final product in the number of 105-level; film cross-section by scanning electron microscopy were characterized by very smooth without a sectional crosslinking, while the modified cross-section is very rough.

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