Study On Continuous Production Process Of Ethylene Glycol Dimethacrylate

Ethylene glycol dimethacrylate(EGDMA),as an important functional acrylate,contains C=C and carboxyl-derived functional groups in its molecular structure.When it participates in polymer copolymerization,it will make the copolymer weather resistant.Water resistance,heat resistance,often used for chemical modification.As an important cross-linking agent in industrial production,it is often used as a cross-linking agent for plastics,rubber,sheet pipe,PVC,ABS and ion exchange resins,and also as a polymerization monomer to prepare coatings and adhesives.In this thesis,a new esterification method is adopted through literature and experiments.Hydroxyethyl methacrylate(HEMA)and methacrylic acid are used as raw materials to synthesize EGDMA.The catalyst is selected and the process is optimized under normal pressure,and the hydrogen NMR spectrum is adopted.,Gas chromatography,infrared spectroscopy and other methods to characterize the structure of the product.On the basis of small-scale experiments,the catalytic reaction distillation device is used to achieve continuous preparation,and the continuous process is optimized;continuous distillation is used to separate MAA and EGDMA.Process optimization of distillation separation process.The main research is as follows:(1)The esterification reaction of HEMA and MAA: HEMA and MAA are used as raw materials for the esterification process.Suitable inhibitors and catalysts are screened for the esterification process.The reaction time t,the reaction temperature T,n(HEMA): n(MAA)W(cat.)and other influencing factors were investigated and optimized: p-hydroxyanisole polymerization inhibition,p-toluenesulfonic acid catalysis,t=3h,T=110 ?,n(HEMA):n(MAA)=1.0:2.4,When w(cat.)=4%,the one-time yield of EGDMA can reach 75.93%.(2)Continuous catalytic reactive distillation to produce EGDMA: In order to increase the conversion rate of HEMA,catalytic reactive distillation equipment is used,and p-toluenesulfonic acid is used as a catalyst to dissolve in the raw material and flow into the reactive distillation equipment to participate in the reaction.The pressure and feed rate of the catalytic reactive distillation system are investigated.The influence of feed volume,n(HEMA):n(MAA)and feed temperature on HEMA conversion rate.The results show that there is a contradictory relationship between the conversion rate of the raw material HEMA and the selectivity of the product EGDMA to a certain extent.Orthogonal optimization of the process: when the pressure is 75 k Pa,the feed temperature is 125 ?,the feed rate is 300g/h and n(HEMA):n(MAA)=1.0:4.0,when the distillation tower system is insulated,at this time The conversion rate of HEMA is 97.98%,and the selectivity of EGDMA is stable above 80%.(3)Continuous distillation and separation of MAA: Continuous distillation is used to separate MAA.Experimental results show that there is a contradiction between the change in the content of MAA at the bottom of the tower and the change in the content of EGDMA at the top of the tower.The experimental results show that the pressure,temperature and feed volume of the rectification separation system have a greater impact on the separation of MAA,and the reflux ratio has a small effect on the separation of MAA.Under the optimal conditions: pressure 1 k Pa,temperature 70 ?,and feed rate 200 g/h,the MAA content at the bottom of the tower is less than 0.3%,and the EGDMA content at the top of the tower is less than 1.7%.(4)Continuous rectification and separation of EGDMA: The experimental results show that there is a contradiction between the change in the content of EGDMA at the top of the tower and the change in the content of diethylene glycol dimethacrylate(DEGDMA)at the bottom of the tower.The pressure of the rectification separation system,the temperature of the rectification column,The feed rate and the control of the reflux ratio at the top of the tower have a greater impact on the change of the EGDMA content at the top of the tower and the change of the DEGDMA content at the bottom of the tower.Under the optimal process conditions: at a pressure of 10 k Pa,a temperature of 105 ?,a feed rate of 200 g/h,and a reflux ratio of 10:6,the EGDMA content at the top of the tower can be over 97%,and the DEGDMA content in the bottom of the tower can be over 90%.In this paper,EGDMA was synthesized from the esterification reaction of HEMA and MAA,and the feasibility of the esterification reaction was verified.The continuous production of EGDMA is realized by the catalytic reaction distillation unit,and MAA and EGDMA are separated by continuous distillation,and finally the continuous production and separation process is realized.