Development Of Waterborne Epoxy Ester Antirust Paint

Epoxy ester antirust paints are widely used because of their convenient coating application,low price,tough film,good adhesion and corrosion resistance.The traditional solvent-based epoxy ester antirust paint has serious environmental and safety problems,so that a waterbore paint has become its development direction.However,waterborne epoxy ester antirust paint has the problems of slow drying,low hardness,poor water resistance and corrosion resistance compared with solvent type.Therefore,it is of great significance to develop high performance waterborne epoxy ester antirust paint.In this paper,a waterborne dual cross-linkable epoxy ester modified with styrene-acrylic resin was prepared through the esterification of epoxy resin（E-20）and linoleic acid,then esterification with maleic anhydride,and followed by grafting copolymerization with styrene（St）,diactone acrylamide（DAAM）,methacrylic acid（MAA）and 2-hydroxyethyl acrylate（HEA）,finally neutralization with N,N-dimethyl ethanolamine（DEMA）.The experimental results show that:The optimal sythetic conditions for epoxy ester are as follows:using tetrabutyl ammonium bromide（TBAB）and Zn O as catalysts,xylene as a water carrying agent,n（E-20）:n（linoleic acid）=1:3,w（E-20+linoleic acid）:w（TBAB）:w（Zn O）:w（xylene）=1:0.0065:0.002:0.24,the esterification temperature being 185-200℃,and the esterification time being 4 h.Under the above conditions,the acid value of epoxy ester is 4.61 mg KOH·g^-1,and the esterification rate of linoleic acid is 95.05%;The optimal conditions for the esterification of the epoxy ester and MA are as follows:n（epoxy ester）:n（MA）=1:1.0;the esterification temperature being 95±5℃,and the reaction time being 3 h.Under the above conditions,the acid value of the maleated epoxy ester is 29.55 mg KOH·g^-1,and the esterification rate of MA is 100%;The optimal conditions for the grafting copolymerization are as follows:w（mateated epoxy ester）:w（styrene+acrylic monomer）:w（ethylene glycol monobutyl ether）=70:30:42.9,the mass fractions of St,MAA,HEA,DAAM,2-mercaptoethanol and 2,2-azobisisobutyronitrile based on the weight of the total monomers（containing mateated epoxy ester）being repectively 17.5%,2.5%,2.5%,5.0%,0.5%and 2.0%,the polymerization temperature being 105±5℃,and the polymerization time being 4 h.Under the above conditions,the monomer conversion rate is 99.45%,and the acid value of the product is 45.83 mg KOH·g^-1;The optimal conditions for the neutralization are as follows:w（modified epoxy ester）:w（DEMA）:w（water）=1:0.04:1.35,the neutralization temperature being 60±5℃,and the neutralization time being 30-45min.The waterborne dispersion of the modified resin prepared according to the above conditions is a transparent solution with a solid content of 36%and a viscosity of 8200 m Ps·a,which is not stratified after standing for 24 days at room temperature.Using the water-based resin as a film-forming substance and adipic acid dihydrazide（ADH）as a cross-linking agent,the preferred formula of the prepared antirust paint is as follows:w（water-based resin）:w（anti-rust pigment）:w（filler）:w（drier）:（ADH）:w（H₂O）:w（color paste）:w（other additives）=34.00:6.00:20.00:0.95:0.20:30.65:6.00:2.20.The surface drying time and actual drying time of the above anti-rust paints are 8min and 110 min respectively,the hardness of the film is HB,the impact strength is50kg·cm,the adhesion is grade 0,the water resistance time is 168 hours,and the salt spray resistance time is 360 hours.The above performances show that the anti-rust paint has some merits such as quick drying,excellent physical properties and anti-corrosion properties of the film.