Study On Preparation And Application Of Fluorosilicon-Modified Acrylate Soap-Free Emulsion

Perfluorinated acrylate polymer has low surface free energy whichgives the film excellent waterproof and oil resistance properties. At thesame time, this kind of polymer has some defects, such as bad lowtemperature resistance, expensive price,poor adhension of the film andpoor wettability to the pigment and packing, so it can’t be widely used.The small size effect,surface effect,quantum size effect and quantumtunnel effect of nano-SiO₂can endue the polymer with specialphoto-electromagnetic effect,after modified by the organic siliconwhich has very fine high and low temperature resistance, low surfacefree energy and weather resistance,then by copolymerization withfluorinated monomer can prepare one type of organic/inorganiccomposite which makes excellent properties of three monomers containin one copolymer.With water as dissolvent,the organic/inorganiccomposite emulsion is more environmental protection and cost saving,italso has the properties of low film forming temperature,strongadhensive power on the base material, strong water and solventresistance,etc.The fluorosilicon-modified acrylate was obtained by soap-freeemulsion polymerization in which TEOS was first hydrolyzed intonano-SiO₂under the presence of NH₃·H₂O, then it was modified byγ-Methacryloxypropyl trimethoxy silane （KH-570）, at last,perfluorinated alkyl ethyl acrylate （FM）, methacrylic acid （MMA）,butyl acrylate （BA）,2-chloro-1,3-dimethyl imidazolinlium chloride （DMC） were added with oil-soluble azodiisobutyronitrile （AIBN） andwater-soluble potassium sulfate （KPS） as initiaters, hydroxyethylacrylate （HEA） as crosslinking agent. The fluorosilicon-modifiedorganic/inorganic hybrid emulsion made was stable. The structure of thelatex films were characterized by fourier transform infraredspectroscopy （FT-IR）, thermal gravimetric analysis （TGA） and X-Raydiffraction（XRD）; the particle size and its distribution of the emulsionwas characterized by dynamic light scattering（DLS） and transmissionelectron microscopy （TEM）; the surface morphology and roughnes ofthe film was characterized by atomic force microscope （AFM）; thewater and oil repellency of the film was characterized by contact angelmeter; the stability of the emulsion was characterized by dynamicrheometer; the morphology of the paper sized by the emulsion wascharacterized by scanning electron microscopy （SEM）.The results of the study were showed as follows:（1） The best hydrolysis condition of TEOS:reaction temperature was70℃, the optimal pH was8.0,the reaction time was12h. The bestsynthesis conditions of fluorosilicon-modified acrylate: reactiontemperature was80℃, the ratio of the monomers was m（FM）:m（MMA）:m（BA）:m（DMC）:m（KH-570）:m（HEA）=56:60:30:40:4:1in the presenceof0.5%（ω） AIBN and KPS, with the ratio of mixed solventm（DMF）:m（CH3CH2OH）was1:1（the total mass was equal to all thepolymerization monomers）.（2） The results showed that the modified nano-silica and thefluorinated monomers had successfully brought in the copolymer; thenano size particles were smooth and spherical with single-type, uniformand narrow-dispersed distribution. The average particle size was90.6nm.（3） When ω（FM） was30%, ω（modified nano-silica） was10%, theproperties of the latex film achieve maximum effct, the contact angle ofwater on the copolymer latex films was114°, water absorption wasless than10%, the pencil hardness was2H,adhesion was1grade. The latex films were undamaged after soaking in various solvents for24h.（4） The dynamic rheometer analysis showed that the fluorosilicon-modified acrylate emulsion had networks which were hard to destroy,the stability of the modified emulsion was much better.（5） After dispersing nanosize silica powder in ethanol whose massratio was1:100for2h, adding the other polymerization monomers, themass ratio of which was m（KH-570）:m（FM）:m（MMA）:m（BA）:m（DMC）:m（HEA）=4:56:60:30:40:1, in the same way, the fluorosilicon-modifiedacrylate was obtained.Compared with the copolymer modified byhydrolyzing of TEOS, the heat stability and crystallinity of thecopolymer were reduced, the average particle size was115.3nm, therewas part of reunite in the emulsion.（6） In the presence of1%（ω）finishing agent, the water repellence ofthe paper surface can achieve to100point, the oil repellence canachieve to6grade. The SEM photos showed that after adding the sizingagent, the fiber in the paper surface combined uniformly and closely.