Study On Polyacrylate/Nano-TiO₂Composite Latex By Double In Situ And Free-Emulsion Polymerization

Recently, acrylic resin was widely used as leather finishing materials. Withenvironment awareness and the continuous improvement of living standardsrising, the requirement of the performance of leather is improved on the premiseof environmental friendly, especially leather surface finishing. Except for therequirements of conventional performance, some special performance such asanti-bacterial sterilization and anti-yellowing are required.Poly（methyl methacrylate/butyl acrylate/vinyl acetate/acrylamide）P（MMA/BA/VAc/AM）/nano-TiO₂composite latex was synthesized via in-situand free-emulsion polymerization with butyl titanate as the precursor ofnano-TiO₂and P（BA/VAc/AM） as the stabilizer, based on the previous studies inour group. The effects of the synthetic conditions ofP（MMA/BA/VAc/AM）/nano-TiO₂composite latex were investigated in details.The P（MMA/BA/VAc/AM）/nano-TiO₂composite latex were characterized byFourier Transform Infrared Spectrometer（FTIR）， Transmission ElectronMIcroscope（TEM）， Thermogravimetric analysis（TGA）, Dynamic LightScattering（DSL）, X-Ray Diffraction（XRD） and Contact Angle（CA）. At last, theabove latexes were applied in leather finishing, and the applied properties of thefinished leather were determined in detail.The best polymerization conditions of the P（MMA/BA/VAc/AM）/nano-TiO₂were as follows: the use level of P （BA/VAc/AM） was45%, the storagetime was two days, nBA：nMMA=3:3, the reaction time was2h, the reactiontemperature was80℃, the use level of Ti（OBu）4was3%, the organic siliconagent was A-151and the use level of the organic silicon agent was4%, the pHwas7and the use level of PEG-400was3%. The elongation at break and tensilestrength of P（MMA/BA/VAc/AM）/nano-TiO₂composite film were increased by18.33%and14.53%in contrast to that of P（MMA/BA/VAc/AM） film. Besides, P（MMA/BA/VAc/AM）/nano-TiO₂composite film has the anti-bacterialproperties and anti-yellowing properties At last, The properties of leatherfinished by P （MMA/BA/VAc/AM）/nano-TiO₂composite in contrast toP（MMA/BA/VAc/AM） film were improved: the water vopor permeabilityincreased by58%, air permeability increased by315.33%, the water resistancedecreased by3.52%.Results of the characterization showed: Nano-TiO₂existed in polyacrylate,and mainly existed in surface of the polyacrylate latex particles. The particlesize of P （MMA/BA/VAc/AM）/nano-TiO₂composite latex was bigger than thatof the pure polyacrylate latex, but the stabilization of the composite latexdecreased. The incooperation of titanium dioxide improved the thermal stabilityof the composite film, but the contact angle of it decreased.