Preparation And Properties Of Silicone-Modified Waterborne Alkyd Resins

Waterborne alkyd resin has become an excellent environment-friendly materials because of its species diversity, flexible formula,simple process and low VOC content. However, there are also obvious shortcomings,such as high baking temperature, insufficient heat resistance, poor water resistance, corrosion resistance. In view of the above shortcomings, this paper adopts silicone prepolymer modified waterborne alkyd resin, and then mixed with amino resin to prepare coatings. Finally,the performance of coatings, such as resistant to corrosion and heat-resistant properties were greatly improved. Similar study had not been found in published reports.(1) waterborne alkyd resin were prepared mainly by linseed oil and trimethylolpropane as raw material which had about 50% content,5.3 Pa·s viscosity,55% oil-length.The structure of the waterborne alkyd resin were characterized by FT-IR. The average particle size of water-borne alkyd resin is 15.09 nm and PDI is 0.265. therefore its particle size distribution and storage stability is excellent. It is better to control the acid value in 45-60mgKOH/g. The synthetic temperature of waterborne alkyd resin was 230℃. the introduction of hydrophilic chainextender temperature was 180℃and we choose trimethylamine as neutralizing agent.(2) Silicone oligomer was synthesized from the reaction of MTES and TEOS as main raw materials, which were used to prepare waterborne silicone-modified alkyd resin. Finally, we can get silicone modified waterborne alkyd resin.The structure,heat properties and molecular weight of the modified alkyd resin were investigated respectively by FT-IR, DSC, TGA and GPC. Then the amount of deionized water, the dropping rate, Silicone synthesis catalyst, water resistance of silicone modified alkyd resin were discussed. The results show that When the amount of silicone oligomer was 12%, the baking film of silicone-modified waterborne alkyd resin have good thermal stability and water resistance performance.50℃ and HC1 was chosen for silicone oligomer synthesis temperature and catalyst.(3) Silicone oligomer was synthesized mainly from the reaction of PhSiCl3, MeSiCl3 and (Me)2SiCl2,which were used to prepare waterborne silicone-modified alkyd resin. Finally we can get silicone modified waterborne alkyd resin.The structure of modified alkyd resin were characterized by FT-IR.The Optimal ratio was chosen through orthogonal experimental design. Hydrolysis temperature, stirring speed, solvent Selection and the amount of silicone were discussed.The results show that when the amount of organic silicone was 12%, the baking film of silicone-modified waterborne alkyd resin have good thermal stability and water resistance performance. Hydrolysis conditions are:R/Si=1.3,Ph/Me=l,m (acetone):m (Xylene):m (water)= 1:2:4;the hydrolysis temperature is 55℃..(4) silicone-modified alkyd resin coatings were prepared with self-made silicone-modified waterborne alkyd resin, right anti-rust paint, the rational design of pigment to binder ratio and orthogonal experiments. The effects of film properties were discussed about use of Coalescent, wetting, dispersing agents, defoamers and other additives. The selection of paint baking acid catalyst, as well as the choice of coating curing temperature and acid and alkali salt coating properties were discussed.