Preparation Of Polyester-Acrylate Hybrid Polyol Aqueous Dispersion

This thesis was mainly about the detailed study of the hybrid polyols of polyesterand polyacrylate for two-component waterborne polyurethane coatings. Two parts wereincludes in it, the first part was the preparation of polyester-acrylate hybrid polyolaqueous dispersions by esterification and the second part was the preparation ofpolyester-acrylate hybrid polyol aqueous dispersions with interpenetrating networkstructure.(1) The polyester-acrylate hybrid polyol was prepared by the esterification withpolyols, polybasic acids,5-SSIPA and a polyacrylate prepolymer synthetized frommethyl methacrylate, butyl acrylate and acrylic acid, with the structure of amacromolecular polyester. It achieved water-solubility by means of bringing sulfonategroup in the chain of the hybrid polyol directly without neutralizing with amine. Thefactors affecting the hybrid aqueous dispersions and the film properties had beendiscussed through the test on TG, GPC, viscosity, particle size, Zeta potential and thebasic coating performances. The experimental results showed that acrylate prepolymermet the requirement of the thermal stability under the the reaction temperature of220℃. The suitable content of acrylic was7%~8%. Appropriate dosage of initiator was5%~6%. The optimized alcohol excess was1.3~1.4. The storage stability of the hybridpolyol aqueous dispersions was increased to a certain extent with increasing thecontent of5-SSIPA, but there was still a certain distance away from the ideal state.Supplemented with amine with the neutralization was between30%~60%, the hybridpolyol aqueous dispersions could be stored30days under the environment of50℃.The polyester-acrylate hybrid polyol based on sulfonate showed better water resistanceand corrosion resistance, but lower storage stability than the hybrid polyol neutralizedby amine when we compared the performance of the hybrid polyols with differenthydrophilic groups.(2) The polyester-acrylate hybrid polyol with a structure that was similar to theinterpenetrating network was prepared by a method of fractional steps which swelledand polymerized the acrylate monomers in the chain segments network of the preparedpolyester polyols, and optimal method of preparing the polyester-acrylate hybrid wassought from three different ways. It achieved water-solubility by the formation of saltthrough neutralizing with amine. The ratio of polyester and polyacrylate, dosage of initiator, the glass transition temperature which affects the performance of the hybridaqueous dispersions and the coating film had been researched. The results indicatedthat the hybrid polyol with the highest degree of interpenetrating and the bestcompatibility would be obtained when dropped the mixture of acrylic monomers andpolyester at the same time. The aqueous dispersion and corresponding film had betterperformances when the content of polyester was20%~30%, the dosage of initiator was3%~4%, the Tgof the polyacrylate was25℃~35℃. The interpenetrating networkstructure in hybrid polyol could effectively enabled the creation of synergies betweenthe two polyols, and got superior performance than either single component.