The surface of nano-silica sol was modified by vinyl triethoxy silane, in which the vinyl groups were grafted onto the surface. Then the nano silica sol modified polysiloxane miniemulsion was synthesized by in-situ emulsion polymerization by reaction of it with vinyl silicone monomer and acrylate monomer using potassium persulfate as initiator. The influence of polymerization temperature and emulsifier on the emulsion polymerization stabilities, water absorption rate of latex film and the particle size of the latex were studied systematically. The results indicated that the conversion rate was the highest when the emulsion polymerization temperature was controled respectively at 80 ℃,90 ℃, when the emulsifer of AEO and LAS were used with a mass ratio of 1.5: 1~2: 1 and the emulsifier content used in the range of 1. 5%-2.0%. The emulsion polymerization stability was the best and the water absorption rate was as low as 3. 0% then. The TEM results showed that the structure of latex particles were nano-SiO2 as the core, silicone polymer as shell. And the number of free SiO2 particles in nano composite latex was much less than that in the blend of polysiloxane emulsion and silica sol.
By using a combination process of precipitation and extraction and modification by silane coupling agent A174, a 15% nano-silica polyether diol dispersion was prepared,which was directly used as raw material to react with polyether diol( poly(propylene glycol)),isophorone diisocyanate (IPDI), 2, 2-Dimethylol propionicacid(DMPA), trimethylol propane (TMP), triethylamine (TEA), ethylene diamine(EDA) to synthsize a serious of modified WPU samples with different nano-SiO2 particle content. The influence of the amount of nano-SiO2 on the properties of emulsion and coating film was studied. The results showed that the nano-SiO2 modified polyether diol and prepolymer were reacted; the dispersion of modified SiO2 in the waterborne polyurethane was good when the amount of nano-SiO2 was 2% of prepolymer, leading a stable waterbome polyurethane dispersion, with a film elongation at break 300%, tensile strength 13 MPa, and improved water resistance, hardness thermal stability.
Using self-crosslinking monomer1008)and HEA an alterative of N-methylol acrylamide), and BA and St as the basic raw material, through the pre-emulsion prepared by semi-continuous seed emulsion the eco-friendly self-crosslinking polyacrylate adhesives for printing was prepared. The effects of anionic, non-ionic emulsifiers, initiator, acrylic acid, hydroxyethyl acrylate (HEA) and homemade crosslinking monomer on the emulsion properties (color fastness, water absorption and viscosity) was discussed. The performance of environmen self-crosslinking latex emulsion was compared with the traditional methylol acrylamide emulsion. The results showed that when w(e-mulsifier)=1.82%,w(APs)=0.41%,w(AA)=3.43%,w(HEA)=3.32%,w(1008)=0. 68%, the adhesive prepared showed excellent printing properties, and the residual formaldehyde was complied to the regulation to meet the performance of fabric printing.
A Mgo coating with initial moisture content over 70% was studied by microwave drying. A response surface methodology central composite experimental design ( CCD) was employed to optimization process parameters. The experimental results and analysis showed that the drying time, materal power rato, the initial moisture content, microwave drying time were all present influence on the relative dehydration rates. The significant order of impact : drying time > material power ratio > initial moisture. Combined the response surfaces methodology optimization and product quality scoring method to get the optimum first phase dry conditions:microwave power 280 W, drying time 30 min. For coatings with 2. 0 mm thickness, the predicted relative dehydration rate was 37. 87%, while the measured actual relative dehydration rate was 37. 55%, the experimental and predicted values of deviation was only -0.32%,indicating the effective response surface optimization.
