Preparation Of Acrylic Modified Waterborne Alkyd Resin

As the wide range of uses, the modification methods and Waterborne methods of the alkyd resin have always been the hot topics in the study of coating. This paper discusses a new method of modifying alkyd resin with acrylic. Two parts were included in this paper. The part I described the preparation of waterborne sulphonated alkyd resin made from the fatty acid that was extracted from the paper industrial, and the part II researched the preparation of one-component acrylic modified alkyd coating drying at room temperature.(1) A polyester intermediate was synthesized by5-sulfoisophthalic acid monosodium salt (5-SSIPA) and neopentyl glycol (NPG), and then the aqueous alkyd resin dispersion was prepared from the esterification of the intermediate polybasic acid, polyols, fatty acids, phthalic anhydride (PA) and a small amount of maleic anhydride (MA). The structure, molecular weight and the stability of the modified alkyd resin had been analysed by FT-IR, GPC and LPSA. The effect of the content of MA, catalytic agent and the percentage composition of polyester intermediate on the physical and chemical properties of the waterborne alkyd resin were investigated. The experimental results showed that the reaction time could be shortened remarkably by the addition of catalyst:the stability and molecular weight of the waterborne alkyd resin have been improved greatly when a small amount of MA was used instead of PA, and it also could offer double bond for the acrylic modified at the same time. The dispersion showed the bigger molecular weight, the better stability, the smaller dispersion viscosity and particle size when about3wt%MA and23wt%intermediate were used, and the alkyd resin showed good dispersibility without neutralizer.(2) The Acrylic modified alkyd resin dispersion was prepared by the emulsion polymerization of acrylate monomer, styrene, initiating agent and alkyd resin dispersion mentioned above. The finally product showed the ability of quick drying, high hardness and good stability. Because of the emulsification of the sulphonated alkyd resin, there had no needed of any emulsifier in the emulsion polymerization. The structure, molecular weight and stability of product had been characterized by FT-IR, GPC, SEM and LPSA. The influences of the content of acrylate monomer, amount of initiating agent, reaction temperature and dryer on the physical and chemical properties of the modified alkyd emulsion were investigated. The experimental results showed that the emulsion and the final film had the ability of good stability, high molecular weight, small particle size, good particle size distribution, high solid content(about50%), high hardness, quick drying (<1h), good water resistance and acid proof when55wt%acrylate monomer,0.5wt%～0.6wt%APS (account for total amount of monomer) were used, and the suitable reaction temperature was80℃. The chemical properties and mechanical properties of the Acrylic modified alkyd dispersion were much better than the unmodified alkyd dispersion.