Microwave Synthesis Of 4-Hydroxybutyl Acrylate And Its Application In Coating Resin Preparation

In the coating industry,4-hydroxybutyl acrylate(4-HBA)is a new type of hydroxyacrylic acid monomer developed in recent years.Compared with common hydroxyethyl acrylate and hydroxypropyl acrylate,its performance has obvious advantages.Acrylic resin containing 4-HBA has excellent properties such as adhesion,gloss,scratch resistance,chemical resistance,etc.It is suitable for automotive coatings,architectural coatings and adhesives.However,4-HBA has not been widely used,which is closely related to its high cost of preparation.In response to this problem,In this thesis,4-HBA was synthesized by microwave synthesis technology,and its application in coatings was preliminary studied.The specific content is as follows:(1)Under the catalysis of solid superacid catalyst A,4-HBA was synthesized from 1,4-butanediol(BDO)and acrylic acid(AA)by esterification using microwave irradiation.The factors which can influence the esterification rate of 4-HBA such as reaction temperature,microwave irradiation time,microwave power,catalyst dosage and molar ratio of alcohol to acid were explore and discussed.Based on the single factor experiment,in condition of 110 ? fixed reaction temperature and 700 W microwave power,these three factors of microwave irradiation time,the catalyst dosage and molar ratio of alcohol to acid were optimized by using Box-Behnken response surface methodology.The best result is n(BDO):n(AA)= 2.9:1,catalyst ratio of 3.5%(the total mass of the reactants,the same below),reaction time of 26 min,the average esterification rate of 4-HBA could reach to 70.04%after repeated 3 times with the above optimal experiment condition.Comparing the conventional heating with the microwave radiation synthesis method,it was proved that the microwave synthesis method can greatly shorten the reaction time and improve the reaction efficiency.The structure of the product was characterized by FT-IR and NMR,which proved that the prepared compound was the target product.(2)Under the catalysis of Catalyst A,the influence of factors such as microwave power and catalyst dosage on reaction kinetics was investigated.The reaction kinetics of synthesis of 4-HBA by microwave irradiation and conventional heating was studied.The results showed that:Compared with the conventional heating method,the reaction activation energy under microwave irradiation decreased by 6.53%and the pre-exponential factor increased by 37.50%,reflecting the "thermal effect" and "non-thermal effect" of microwave.(3)The synthesis of 4-HBA was carried out on a continuous tube-type microwave generator under the catalysis of Catalyst B.The effects of alkyd molar ratio,catalyst dosage,flow rate of mixed solution and microwave power on esterification rate were investigated.On the basis of single-factor experiments,orthogonal experiments were used to optimize the process of continuous microwave synthesis of 4-HBA.The optimal synthesis conditions were:n(BDO):n(AA)= 5:1,catalyst dosage 1.0%,the flow rate of the mixture 5 mL/min,the microwave power 2500 W,and its ester was reacted through three cycles,The rate is up to 84.36%.A molecular distillation apparatus was used to separate and purify 4-HBA.(4)Using methyl methacrylate,styrene,butyl acrylate,4-HBA and AA as the main monomers,a semi-continuous dropping method and free-radical solution polymerization method were used to prepare the aqueous hydroxyl group containing high activity 4-HBA.The effects of reaction temperature,type and amount of initiator,and amount of 4-HBA on the properties of the resin were investigated.The structure of the resin was characterized by infrared spectroscopy.The properties of the resin were analyzed using a thermogravimetric analyzer and a laser particle size scatterometer.The results showed that:when the reaction temperature is 85 ?,the initiator dosage is 1.5%(total monomer mass,the same below),the amount of MMA is 32.0%,the amount of St is 19.0%,the amount of BA is 33.0%,the acrylic acid dosage is 6.0%,and the 4-HBA dosage is 10.0%.When the degree of neutralization is 100%,the solid content of the prepared water-borne hydroxyacrylic resin can reach 30%,indicating that the addition of 4-HBA helps to increase the solid content of the acrylic resin.The synthesized resin has good thermal stability,and the size of the emulsion is moderate and evenly distributed.And it has good acid and alkali resistance and water resistance.