| Epoxy resin coatings have the advantages of high bond strength,good mechanical properties,and strong corrosion resistance,and have been widely used in the field of anti-corrosion coatings.However,epoxy resin coatings have a problem of poor flexibility.At present,epoxy resin coatings are mainly solvent-based,which does not meet the trend of environmental protection.In order to solve the deficiencies in the application of traditional epoxy resin coatings,emulsion polymerization method was adopted to synthesize acrylate modified epoxy resin emulsion.The synthesis process was optimized and the properties of emulsion and coating film were investigated.In this paper,epoxy resin(E-44),n-butyl acrylate(BA),styrene(St)were used as raw materials,ammonium persulfate(APS)was used as initiator,and Triton(X-100),3-Allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt(COPS-1),and ethoxylated alkyl Ammonium ether sulfate(CO436)were used as a composite emulsifier.Acrylate was grafted onto the epoxy resin segment by the method of chemical modification,and acrylate graft modified epoxy resin emulsion was synthesized.The structure of the acrylate graft modified epoxy resin was characterized by Fourier transform infrared spectroscopy(FTIR),which proved that the acrylate copolymerized and grafted onto the epoxy resin segment.The effects of the initiator,the emulsifier,the monomer ratio,and the amount of the epoxy resin on the emulsion stability and the coating performance were investigated.The experimental results show that,the reaction temperature is 75 ~oC;the reaction time is 5 h;the amount of initiator is 0.8%;the composite emulsifier ratio X-100:COPS-1:CO436 is 1:1:1;the amount of emulsifier is 4%;the ratio of soft monomer,butyl acrylate(BA)and hard monomer,styrene(St),is 1:1;the amount of epoxy resin is 25%.The synthetic acrylate modified epoxy resin emulsion whose grafting rate is 37.3%,pencil hardness is 3 H,flexibility is 1 mm,tensile strength is12.45 MPa,and elongation at break is 682%,is of good stability.In this paper,a two-step method was used.Firstly,St and triphenylphosphine(PPh3)used as solvent and catalyst respectively,AA and E-44 were reacted to obtain a St solution of an acrylated modified epoxy resin(EOA).Then,using EOA,St,BA used as monomer,APS used as initiator,X-100,COPS-1,CO436 used as emulsifier,the emulsion polymerization was used to synthesize acrylate ester modified epoxy resin Emulsion.The changes of structure during the synthesis of acrylate-esterified epoxy resin emulsion were characterized by FTIR.It is proved that the double bond was successfully introduced into the EOA,and the polymerization occursed in acrylate esterified epoxy resin emulsion.The influences of initiator,emulsifier,monomer ratio and amount of epoxy resin on emulsion stability and coating performance were investigated.The experimental results show that the best EOA solution is synthesized when the reaction temperature is 120 ~oC,the reaction time is 90 min and the ratio of E-44:AA=1:1.3 in the first step.In the second step,the low crosslink density acrylate modified epoxy resin emulsion was synthesized.,under the conditions that the reaction temperature is 75 ~oC,the reaction time is 4h,the ratio of the soft and hard monomer BA:St is 6:4,the amount of E-44 is 25%.The degree of crosslinking is up to 94.5%,the pencil hardness of coating film is 2 H,the flexibility is 1 mm,the tensile strength is 12.0MPa,and the elongation at break is 160%.The acrylate modified epoxy resin emulsion is of good coating performance. |
PDF Full Text Request