Preparation Of Silica Sol Modified Hydroxy Acrylic Emulsion

Hydroxyl acrylic emulsion is an important type of waterborne acrylic resin,and can be formulated with isocyanate as an environmentally friendly waterborne acrylic polyurethane coating.However,the hydroxyl acrylic emulsion for industrial application has poor storage stability,low hydroxyl content and easy to produce flash rust,which limits the popularization and application of hydroxyl acrylic emulsion in the field of waterborne coatings to a certain extent.In view of the above problems,the following work has been carried out in this dissertation.(1)Acrylic emulsion with good storage stability and high hydroxyl content was synthesized using semi continuous seed emulsion polymerization method.The effects of polymerization time and temperature,the type and dosage of emulsifier,the amount of initiator,the type and dosage of functional monomer and the type and amount of hard monomer were studied on the properties of acrylic emulsion and the properties of varnish film.The size and size of latex particles of hydroxyl acrylic emulsion were analyzed by TEM and particle size analyzer.The results show that hydroxy acrylic emulsion with 3.54% hydroxyl group,and the room temperature storage stability exceeding 6 months can be prepared when the mixed monomers reacted at 72 ° C for 10 h consisting of St,BA,HPMA and VV-10 St,BA,HPMA at mass ratio of 35.71:31.43:30:2.86,2.5% of the emulsifier consisting of SDBS,OP-10 and CO-436 at equal mass ratio,0.5% APS used as s initiator.The pencil hardness of waterborne acrylic polyurethane varnish is higher than H waterborne,made of the prepared hydroxy acrylic acid emulsion mixing with the waterborne isocyanate curing agent according to n(-OH):n(-NCO)=1:1.3.(2)Silica sol with anticorrosion function was prepared from sodium silicate and organic carbonate.The effects of types and dosages of sodium silicate,organic carbonate and reaction conditions were investigated on the storage stability of silica sol.The prepared silica sol were characterized by transmission electron microscopy,nanoparticle size analyzer and electrochemical workstation.The results show that the silica sol of better anticorrosion performance and storage stability at room temperature can be prepared when the mass ratio of modified sodium silicate solid to propylene carbonate is higher than 3:1 and the synthetic reaction temperature is 45?.(3)The hydroxyl acrylic emulsion was modified by the synthesized silica sol,the results show that adding silica sol can improve flash rust resistance of waterborne acrylic polyurethane.When the amount of silica sol is 15%,it can effectively inhibit the occurrence of flash rust.