| Alkyd resin has its space in coating industry for its abundant raw material, proper price and good performance. Meanwhile, the disadvantages of alkyd resin system, especially water-borne alkyd resin system, are also clear for us to point out, such as its poor drying performance and water resistance performance. Modifying alkyd resin with silicone monomer, can improve old system with new performances. In the silicone part of modified alkyd resin, electro-negativity between Si and O is higher than C and C in common polymer. Si-O have stronger polarity than C-C. Thus, intermolecular force in this system is stronger than other system, then the density of intermolecular crosslink would be higher, system drying performance and water resistance performance would be improved.This article prepares a kind of water-borne alkyd rein based on linseed oil, pentaerythrite, phthalic anhydride, N,N-dimethylol propionic acid(DMPA), diethylene glycol. Then, it prepares a kind of air curable water-borne silicone modified alkyd resin based on silicone monomer and the water-borne alkyd rein mentioned above. During above experiments, the article discusses the impact factors in the process of preparing the products and optimizes the composition and the process parameters.With the result of orthogonal experiment and the process stability, the article designs a composition of preparing water-borne alkyd resin. The results show that: the excess alcohol, functional degree of polybasic and oil length have obvious impact to the performance of water-borne alkyd resin while the impact sequence(from severe to slight) isthe excess alcohol> functional degree of polybasic> oil length. By setting oil length as 55%, the excess alcohol as 1.07, functional degree of polybasic as 3.25, the article gets a kind of water-borne alkyd resin with good film forming and drying performance. The tack free time and curing time of the product are 24 h and 60 h. However, its performances in water resistance, heat resistance and coating hardness can still be improved.With the results of single factor compare method, the article discusses the impacts from various factors during silicone modifying step. prepares a kind of water-borne silicone modified alkyd resin based on the silicone monomer and the product above. After optimization of composition and processes, final product can be solved in water while it obtains better performances in drying, coating hardness, water resistance, heat resistance than water-borne alkyd rein above. This system choose methyl triethoxysilane as silicon monomer while its quantity is 23.5% of the water-borne alkyd resin(w%),n(H2O):n(Si)=1.5:1 and launch the hydrolytic and esterification reaction of the silicon monomer in 85℃..The article use Raman Spectrum, Differential Scanning Calorimeter(DSC), Thermo Gravimetric Analyzer(TGA) to characterize the polymer while use Gel Permeation Chromatography(GPC) to get the relative molecular mass(MM) and its distribution(MMD) and Malvin particle analyzer to get the particle size and its distribution. Raman Spectrum and DSC curve prove that silicone monomer is connected to the chain of alkyd resin. DSC curve shows that Tg of water-borne silicone modified alkyd resin is-17.0℃. And Malvin particle analyzer show that its average particle size is 139.8nm. |
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