Continuous production method of glycidyl methacrylate

Abstract

The present invention relates to the technical field of material chemistry, and in particular to a continuous production method of glycidyl methacrylate. The continuous production method comprises the following steps: preparing iron formate-loaded modified montmorillonite; preparing a composite inhibitor silica sol; generating a crude glycidyl methacrylate; and post-treating the crude glycidyl methacrylate and an aqueous phase. The present invention prepares modified montmorillonite, and uses the modified montmorillonite to load iron formate. When catalyzing the ring-opening of glycidyl methacrylate, as the reaction proceeds, the montmorillonite has fewer acid sites that combine with reactants, and the catalytic activity of the montmorillonite in the middle stage of the reaction will be greatly reduced, thereby causing a decrease in the reaction rate. After loading iron formate, in the middle stage of the reaction, the iron formate can replace the montmorillonite to continue the catalytic reaction, which not only ensures that the reaction is mild and stable throughout the process, but also accelerates the reaction rate and improves production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of material chemistry, and in particular to a continuous production method of glycidyl methacrylate. Background Art

[0002] Glycidyl Methacrylate (GMA) is a colorless, transparent liquid. It is an important functional monomer that contains epoxy and carbon-carbon double bonds. It is environmentally friendly, non-toxic, and has high chemical reactivity. It can undergo both free radical and ionic reactions and can be further cross-linked into a network structure. It is widely used in coatings, adhesives, plastic modification, textile processing, and other fields. It is an important functional fine chemical intermediate raw material with broad application prospects.

[0003] The synthesis of GMA can be carried out by one-step synthesis, esterification-ring closure, catalytic transesterification, lipase catalytic synthesis, etc. Among them, the one-step synthesis of sodium methacrylate and epichlorohydrin has relatively mild reaction conditions, short reaction time, simple operation, low pollution and easy catalyst availability, which is the GMA synthesis process commonly used in the world. Traditional catalysts include inorganic alkaline salt catalysts and organic metal salt catalysts, but inorganic alkaline salt catalysts are more unstable than organic metal salt catalysts, and although organic metal salt catalysts are relatively stable at high temperatures, their catalytic rate is not easy to control, and they need to be used with other additives such as stabilizers, which is costly, and the purity of the produced GMA is reduced, and other processes need to be used for purification in the later stage. In view of the shortcomings of the prior art, the present invention provides a continuous production method of glycidyl methacrylate, which is used to solve the problem of insufficient purity of GMA produced by organic metal salt catalysts and uncontrollable reaction. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a continuous production method of glycidyl methacrylate.

[0005] The continuous production method of glycidyl methacrylate comprises the following steps:

[0006] S1: Preparation of iron formate-modified montmorillonite

[0007] The hydrochloric acid solution and the montmorillonite are mixed, heated, stirred and reacted, then cooled to room temperature, filtered to remove the filtrate, dried the filter residue, crushed and ground to obtain acid-modified montmorillonite, added the acid-modified montmorillonite into deionized water, stirred and dispersed to obtain a suspension, then added iron formate, stirred at a constant temperature to obtain a precipitate, washed with deionized water, then vacuum dried, ground and sieved to obtain iron formate-loaded modified montmorillonite;

[0008] S2: Preparation of composite inhibitor silica sol

[0009] Adding silica sol and N, N-dimethylformamide into a reaction bottle, heating and stirring until completely dissolved, to obtain silica sol dissolved with N, N-dimethylformamide, then adding silica sol and p-methoxyphenol into a reaction bottle, heating and stirring until completely dissolved, and pouring into a spherical silica gel mold before it is completely solidified, the injection amount is half of the volume of the spherical silica gel mold, and the other half is injected with silica sol dissolved with N, N-dimethylformamide, and standing and demolding to obtain a composite inhibitor silica sol;

[0010] S3: Production of crude glycidyl methacrylate

[0011] Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, stir thoroughly, heat up, drop epichlorohydrin therein, keep warm for reaction, obtain an intermediate ring-opening product, drop NaOH solution, keep warm for reaction, then filter while hot, let stand and separate, collect water phase and oil phase respectively, the oil phase is crude glycidyl methacrylate;

[0012] S4: Crude glycidyl methacrylate and aqueous phase workup

[0013] The crude glycidyl methacrylate is centrifuged and then filtered to remove solids to obtain glycidyl methacrylate. The collected aqueous phase is added to a distillation tower and enters from the middle of the distillation tower. The bottom components are then distilled in a sub-tower to obtain glycidyl methacrylate at the top of the sub-tower. The glycidyl methacrylate is combined with the glycidyl methacrylate obtained in step S4.1 to obtain a finished glycidyl methacrylate.

[0014] Furthermore, step S1 of preparing the iron formate-loaded modified montmorillonite comprises the following steps:

[0015] S1.1: Mix the hydrochloric acid solution and montmorillonite in a volume ratio of 1:12, and heat to 50-55°C, stir and react for 20-24 hours, then cool to room temperature, filter and remove the filtrate, dry the residue at 100-110°C for 12 hours, crush and grind it through a 100-mesh sieve to obtain acid-modified montmorillonite;

[0016] S1.2: Add acid-modified montmorillonite into deionized water, stir and disperse to obtain a suspension, then add 10% of the total mass of iron formate, stir at a constant temperature of 65°C for 3-4 hours to obtain a precipitate, wash it twice with deionized water, filter out the filtrate, then vacuum dry it for 48 hours, grind it through a 100-mesh sieve, and obtain iron formate-modified montmorillonite.

[0017] Furthermore, step S2 of preparing the composite inhibitor silica sol comprises the following steps:

[0018] S2.1: Add silica sol and N,N-dimethylformamide in a mass ratio of (3-4):1 into a reaction bottle, heat to 80-100°C, and stir thoroughly until completely dissolved to obtain silica sol dissolved with N,N-dimethylformamide;

[0019] S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 80-100°C, stir thoroughly until completely dissolved, pour into a spherical silicone mold before it completely solidifies, the injection amount is half of the volume of the spherical silicone mold, and the other half is injected with silica sol dissolved with N,N-dimethylformamide. Let it stand for 24 hours and demold to obtain a composite inhibitor silica sol.

[0020] Further, step S3 generates crude glycidyl methacrylate, comprising the following steps:

[0021] S3.1: Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, stir thoroughly, heat to 100-110°C under reflux condensation, place epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add dropwise within 5-6 hours, then heat for 1 hour to complete the ring-opening esterification reaction and obtain an intermediate ring-opening product;

[0022] S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, complete the addition within 3 hours, then maintain the temperature at 40℃ for 1 hour, then filter while hot, wash the filtrate with 60℃ hot water 2-3 times, let it stand and separate the liquids, collect the aqueous phase and oil phase separately, the oil phase is the crude product of glycidyl methacrylate.

[0023] Further, step S4, post-treatment of the crude glycidyl methacrylate and the aqueous phase, comprises the following steps:

[0024] S4.1: centrifuging the crude glycidyl methacrylate at a centrifugal speed of 800-1000 r / min for 15-20 min, and then filtering to remove solids to obtain glycidyl methacrylate;

[0025] S4.2: The collected water phase is added to a distillation tower, and the water phase enters the distillation tower from the middle, and water and epichlorohydrin are evaporated. The bottom components are then distilled in a sub-tower to obtain glycidyl methacrylate at the top of the sub-tower, and combined with the glycidyl methacrylate obtained in step S4.1 to obtain the finished glycidyl methacrylate.

[0026] Furthermore, in step S1.2, the material-liquid ratio of the acid-modified montmorillonite to deionized water is 1:10 g / mL.

[0027] Furthermore, the volume of the spherical silicone mold in step S2.2 is 2 ml.

[0028] Furthermore, in step S3.1, the mass ratio of methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol is (6-8): (0.2-0.5): (2-3).

[0029] Furthermore, the concentration of the NaOH solution in step S3.2 is 25-30wt%.

[0030] Furthermore, in step S4.2, the top pressure of the distillation tower is set to 6 kPa, the reflux ratio is 1, the feed temperature is 40°C, the feed pressure is 120 kPa, the feed flow rate is 500 kg / h, the condenser temperature is 8-12°C, and the reboiler temperatures are 45°C, 85°C and 132°C respectively.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] 1. The present invention prepares modified montmorillonite, and uses the modified montmorillonite to load iron formate and add it to the reaction of methacrylic acid and epichlorohydrin to prepare glycidyl methacrylate. Acid treatment can partially dissolve the structural units of the montmorillonite, increase the interlayer distance, and thus increase its specific surface area, which is beneficial to improving the dispersibility and compatibility of the montmorillonite in the polymer matrix. In addition, due to the increase in specific surface area, the surface activity of the montmorillonite increases, and it is easier to adsorb organic molecules. Then, the montmorillonite can be well loaded with iron formate, and the montmorillonite can be used as a solid acid catalyst when catalyzing the synthesis of glycidyl methacrylate. After that, when catalyzing the ring-opening of glycidyl methacrylate, as the reaction proceeds, the catalytic activity of montmorillonite in the middle stage of the reaction will drop significantly after the fewer acidic sites of montmorillonite combine with the reactants, resulting in a decrease in the reaction rate. After loading iron formate, in the middle stage of the reaction, iron formate can replace montmorillonite to continue the catalytic reaction. In addition, iron formate has many acidic sites. If it is added in the early stage of the reaction, it is easy to cause the reaction rate to be too fast, the reaction temperature to be unstable, and more side reactions to form. Therefore, loading iron formate on montmorillonite not only ensures that the reaction is mild and stable throughout the process, but also accelerates the reaction rate and improves production efficiency.

[0033] 2. The present invention mixes N,N-dimethylformamide with silica sol, and further mixes p-methoxyphenol with silica sol to prepare a composite inhibitor silica sol. p-Methoxyphenol can effectively inhibit free radical polymerization reaction and prevent spontaneous polymerization of glycidyl methacrylate during the reaction. In the early stage of the reaction, silica sol is added in the form of dispersed particles. When N,N-dimethylformamide can be used as a solvent to dissolve glycidyl methacrylate, the composite inhibitor silica sol prepared into dispersed particles by silica sol can separately dissolve a small amount of glycidyl methacrylate generated in the early stage of the reaction. At this time, p-methylphenol is not needed as an inhibitor, and, If p-methylphenol is present at this time, it will hinder the reaction of methacrylic acid and epichlorohydrin. Therefore, p-methylphenol is slowly released through the action of silica sol at this time, and only a small amount exists in the reaction system, and a small amount of N, N-dimethylformamide is used to prevent glycidyl methacrylate from polymerizing. As the reaction time increases, silica sol will be released over time in the high-temperature reaction. In the later stage of the reaction, after silica sol releases p-methoxyphenol and N, N-dimethylformamide, N, N-dimethylformamide helps methoxyphenol to be evenly distributed, preventing a large amount of glycidyl methacrylate from cross-linking in the later stage of the reaction, thereby increasing the yield of glycidyl methacrylate.

[0034] 3. The present invention adds iron formate-modified montmorillonite and composite inhibitor silica sol to synthesize and produce glycidyl methacrylate. The montmorillonite and silica sol have different particle sizes. After the reaction is completed, they can be separated by a simple centrifugal operation, and can also be well separated from the generated glycidyl methacrylate. The montmorillonite can be repeatedly used after washing and calcining operations. The cost of silica sol is low, and the effect of improving the purity of the finished glycidyl methacrylate is achieved while reducing the synthesis production cost of glycidyl methacrylate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0036] Figure 1 This is a flow chart of the continuous production method of glycidyl methacrylate used in the embodiment of the present invention. DETAILED DESCRIPTION

[0037] The continuous production method of glycidyl methacrylate provided by the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0038] Embodiment 1:

[0039] A continuous production method for glycidyl methacrylate, such as Figure 1 As shown, the following steps are included:

[0040] S1: Preparation of iron formate-modified montmorillonite

[0041] S1.1: Mix the hydrochloric acid solution and montmorillonite in a volume ratio of 1:12, heat to 50°C, stir and react for 24 hours, then cool to room temperature, filter and remove the filtrate, dry the residue at 110°C for 12 hours, crush and grind it through a 100-mesh sieve to obtain acid-modified montmorillonite;

[0042] S1.2: Add acid-modified montmorillonite into deionized water with a solid-liquid ratio of 1:10 g / mL. Stir and disperse to obtain a suspension. Add 10% of the total mass of iron formate into the system. Stir at a constant temperature of 65°C for 4 hours to obtain a precipitate. Wash it twice with deionized water and filter out the filtrate. Then vacuum dry it for 48 hours and grind it through a 100-mesh sieve to obtain iron formate-loaded modified montmorillonite.

[0043] S2: Preparation of composite inhibitor silica sol

[0044] S2.1: Add silica sol and N,N-dimethylformamide in a mass ratio of 3:1 into a reaction bottle, heat to 80°C, and stir thoroughly until completely dissolved to obtain silica sol dissolved with N,N-dimethylformamide;

[0045] S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 80°C, stir thoroughly until completely dissolved, pour into a 2 ml spherical silicone mold before it is completely solidified, the injection amount is half of the volume of the spherical silicone mold, and the other half is injected with silica sol dissolved with N,N-dimethylformamide. Let it stand for 24 hours and demold to obtain a composite inhibitor silica sol.

[0046] S3: Production of crude glycidyl methacrylate

[0047] S3.1: Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol is 6:0.2:3, stir well, raise the temperature to 100°C under reflux condensation conditions, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0048] S3.2: Adjust the water bath temperature to 40℃, slowly drop NaOH solution, the concentration of NaOH solution is 30wt%, the addition should be completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate the liquids, collect the water phase and oil phase respectively, the oil phase is the crude product of glycidyl methacrylate.

[0049] S4: Crude glycidyl methacrylate and aqueous phase workup

[0050] S4.1: centrifuging the crude glycidyl methacrylate at a centrifugal speed of 1000 r / min for 20 min, and then filtering to remove solids to obtain glycidyl methacrylate;

[0051] S4.2: Add the collected water phase to a distillation tower, set the top pressure to 6 kPa, the reflux ratio to 1, the feed temperature to 40 ° C, the feed pressure to 120 kPa, the feed flow rate to 500 kg / h, the condenser temperature to 12 ° C, the reboiler temperatures to 45 ° C, 85 ° C and 132 ° C respectively, the water phase enters the distillation tower from the middle, water and epichlorohydrin are evaporated, the bottom components are then distilled in the sub-tower, and methacrylic acid glycidyl ester is obtained at the top of the sub-tower, and combined with the methacrylic acid glycidyl ester obtained in step S4.1 to obtain the methacrylic acid glycidyl ester finished product.

[0052] Embodiment 2:

[0053] A continuous production method for glycidyl methacrylate, such as Figure 1 As shown, the following steps are included:

[0054] S1: Preparation of iron formate-modified montmorillonite

[0055] S1.1: Mix the hydrochloric acid solution and montmorillonite in a volume ratio of 1:12, heat to 55°C, stir and react for 20 hours, then cool to room temperature, filter and remove the filtrate, dry the residue at 100°C for 12 hours, crush and grind it through a 100-mesh sieve to obtain acid-modified montmorillonite;

[0056] S1.2: Add acid-modified montmorillonite into deionized water with a solid-liquid ratio of 1:10 g / mL. Stir and disperse to obtain a suspension. Add 10% of the total mass of iron formate to the system. Stir at a constant temperature of 65°C for 3 hours to obtain a precipitate. Wash it twice with deionized water and filter out the filtrate. Then vacuum dry it for 48 hours and grind it through a 100-mesh sieve to obtain iron formate-loaded modified montmorillonite.

[0057] S2: Preparation of composite inhibitor silica sol

[0058] S2.1: Add silica sol and N,N-dimethylformamide in a mass ratio of 3:1 into a reaction bottle, heat to 100°C, and stir thoroughly until completely dissolved to obtain silica sol dissolved with N,N-dimethylformamide;

[0059] S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 100°C, stir thoroughly until completely dissolved, pour into a 2 ml spherical silicone mold before it is completely solidified, the injection amount is half of the volume of the spherical silicone mold, and the other half is injected with silica sol dissolved with N,N-dimethylformamide. Let it stand for 24 hours and demold to obtain a composite inhibitor silica sol.

[0060] S3: Production of crude glycidyl methacrylate

[0061] S3.1: Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol is 6:0.2:3, stir well, heat to 110°C under reflux condensation, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0062] S3.2: Adjust the water bath temperature to 40℃, slowly drop NaOH solution, the concentration of NaOH solution is 30wt%, the addition should be completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate the liquids, collect the water phase and oil phase respectively, the oil phase is the crude product of glycidyl methacrylate.

[0063] S4: Crude glycidyl methacrylate and aqueous phase workup

[0064] S4.1: centrifuging the crude glycidyl methacrylate at a centrifugal speed of 800 r / min for 15 min, and then filtering to remove solids to obtain glycidyl methacrylate;

[0065] S4.2: Add the collected water phase to a distillation tower, set the top pressure to 6 kPa, the reflux ratio to 1, the feed temperature to 40 ° C, the feed pressure to 120 kPa, the feed flow rate to 500 kg / h, the condenser temperature to 12 ° C, the reboiler temperatures to 45 ° C, 85 ° C and 132 ° C respectively, the water phase enters the distillation tower from the middle, water and epichlorohydrin are evaporated, the bottom components are then distilled in the sub-tower, and methacrylic acid glycidyl ester is obtained at the top of the sub-tower, and combined with the methacrylic acid glycidyl ester obtained in step S4.1 to obtain the methacrylic acid glycidyl ester finished product.

[0066] Embodiment 3:

[0067] A continuous production method for glycidyl methacrylate, such as Figure 1 As shown, the following steps are included:

[0068] S1: Preparation of iron formate-modified montmorillonite

[0069] S1.1: Mix the hydrochloric acid solution and montmorillonite in a volume ratio of 1:12, heat to 50°C, stir and react for 24 hours, then cool to room temperature, filter and remove the filtrate, dry the residue at 110°C for 12 hours, crush and grind it through a 100-mesh sieve to obtain acid-modified montmorillonite;

[0070] S1.2: Add acid-modified montmorillonite into deionized water with a solid-liquid ratio of 1:10 g / mL. Stir and disperse to obtain a suspension. Add 10% of the total mass of iron formate into the system. Stir at a constant temperature of 65°C for 4 hours to obtain a precipitate. Wash it twice with deionized water and filter out the filtrate. Then vacuum dry it for 48 hours and grind it through a 100-mesh sieve to obtain iron formate-loaded modified montmorillonite.

[0071] S2: Preparation of composite inhibitor silica sol

[0072] S2.1: Add silica sol and N,N-dimethylformamide in a mass ratio of 4:1 into a reaction bottle, heat to 80°C, and stir thoroughly until completely dissolved to obtain silica sol dissolved with N,N-dimethylformamide;

[0073] S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 80°C, stir thoroughly until completely dissolved, pour into a 2 ml spherical silicone mold before it is completely solidified, the injection amount is half of the volume of the spherical silicone mold, and the other half is injected with silica sol dissolved with N,N-dimethylformamide. Let it stand for 24 hours and demold to obtain a composite inhibitor silica sol.

[0074] S3: Production of crude glycidyl methacrylate

[0075] S3.1: Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol is 8:0.5:2, stir well, heat to 100°C under reflux condensation, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0076] S3.2: Adjust the water bath temperature to 40℃, slowly drop NaOH solution, the concentration of NaOH solution is 30wt%, the dropwise addition should be completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water twice, let it stand and separate the liquids, collect the water phase and oil phase respectively, the oil phase is the crude product of glycidyl methacrylate.

[0077] S4: Crude glycidyl methacrylate and aqueous phase workup

[0078] S4.1: centrifuging the crude glycidyl methacrylate at a centrifugal speed of 1000 r / min for 20 min, and then filtering to remove solids to obtain glycidyl methacrylate;

[0079] S4.2: Add the collected water phase to a distillation tower, set the top pressure to 6 kPa, the reflux ratio to 1, the feed temperature to 40 ° C, the feed pressure to 120 kPa, the feed flow rate to 500 kg / h, the condenser temperature to 12 ° C, the reboiler temperatures to 45 ° C, 85 ° C and 132 ° C respectively, the water phase enters the distillation tower from the middle, water and epichlorohydrin are evaporated, the bottom components are then distilled in the sub-tower, and methacrylic acid glycidyl ester is obtained at the top of the sub-tower, and combined with the methacrylic acid glycidyl ester obtained in step S4.1 to obtain the methacrylic acid glycidyl ester finished product.

[0080] Comparative Example 1:

[0081] Compared with Example 1, the difference of Comparative Example 1 is that the acid modification in step S1.1 is not performed in step S1, and montmorillonite is directly added in step S1.2, specifically: "S1: Preparation of iron formate-modified montmorillonite

[0082] S1.2: Add montmorillonite to deionized water, stir and disperse to obtain a suspension, then add 10% of the total mass of iron formate in the system, stir at a constant temperature of 65°C for 4 hours to obtain a precipitate, wash it twice with deionized water, filter out the filtrate, and then vacuum dry it for 48 hours, grind it through a 100-mesh sieve to obtain iron formate-loaded montmorillonite, and use the iron formate-loaded montmorillonite for subsequent steps to test and calculate the yield and purity of the finished glycidyl methacrylate.

[0083] Comparative Example 2:

[0084] Compared with Example 1, the difference of Comparative Example 2 is that in step S3, iron formate is directly used instead of montmorillonite modified with iron formate, specifically: "S3: generating crude glycidyl methacrylate

[0085] S3.1: Add methacrylic acid, ferric formate and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, ferric formate and composite inhibitor silica sol is 6:0.2:3, stir well, heat to 100°C under reflux condensation, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0086] S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, the concentration of NaOH solution is 30wt%, the addition is completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate, collect the water phase and oil phase respectively, the oil phase is the crude glycidyl methacrylate", test and calculate the yield and purity of the finished glycidyl methacrylate.

[0087] Comparative Example 3:

[0088] Compared with Example 1, the difference of Comparative Example 3 is that in step S3, the iron formate-modified montmorillonite is not used, and the acid-modified montmorillonite is directly used, specifically: "S3: generating crude glycidyl methacrylate

[0089] S3.1: Add methacrylic acid, acid-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, acid-modified montmorillonite and composite inhibitor silica sol is 6:0.2:3, stir well, heat to 100°C under reflux condensation conditions, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0090] S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, the concentration of NaOH solution is 30wt%, the addition is completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate, collect the water phase and oil phase respectively, the oil phase is the crude glycidyl methacrylate", test and calculate the yield and purity of the finished glycidyl methacrylate.

[0091] Comparative Example 4:

[0092] Compared with Example 1, the difference of Comparative Example 4 is that in step S3, montmorillonite is directly used instead of iron formate-modified montmorillonite, specifically: "S3: generating crude glycidyl methacrylate

[0093] S3.1: Add methacrylic acid, montmorillonite and composite inhibitor silica sol into a three-necked flask, the mass ratio of methacrylic acid, montmorillonite and composite inhibitor silica sol is 6:0.2:3, stir well, heat to 100°C under reflux condensation, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain the intermediate ring-opening product;

[0094] S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, the concentration of NaOH solution is 30wt%, the addition is completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate, collect the water phase and oil phase respectively, the oil phase is the crude glycidyl methacrylate", test and calculate the yield and purity of the finished glycidyl methacrylate.

[0095] Comparative Example 5:

[0096] Compared with Example 1, the difference of Comparative Example 5 is that in step S2, only silica sol in which N,N-dimethylformamide is dissolved is used to prepare the composite polymerization inhibitor silica sol, specifically: "S2: Preparation of composite polymerization inhibitor silica sol

[0097] S2.1: Add silica sol and N, N-dimethylformamide in a mass ratio of 3:1 into a reaction bottle, heat to 80°C, stir thoroughly until completely dissolved, and obtain silica sol dissolved with N, N-dimethylformamide. Pour the silica sol into a 2 ml spherical silica gel mold before it is completely solidified, let it stand for 24 hours, and demould to obtain a composite inhibitor silica sol. Test and calculate the yield and purity of the finished glycidyl methacrylate.

[0098] Comparative Example 6:

[0099] Compared with Example 1, the difference of Comparative Example 6 is that in step S2, only silica sol in which p-methoxyphenol is dissolved is used to prepare the composite polymerization inhibitor silica sol, specifically: "S2: Preparation of composite polymerization inhibitor silica sol

[0100] S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 80°C, stir thoroughly until completely dissolved, pour into a 2 ml spherical silica mold before it is completely solidified, let it stand for 24 hours, demold to obtain a composite inhibitor silica sol", test and calculate the yield and purity of the finished glycidyl methacrylate.

[0101] Comparative Example 7:

[0102] Compared with Example 1, the difference of Comparative Example 7 is that step S2 is not performed, and N,N-dimethylformamide and p-methoxyphenol are directly added in step S3, specifically: "S3: generating crude glycidyl methacrylate

[0103] S3.1: Add methacrylic acid, iron formate-modified montmorillonite, N,N-dimethylformamide and p-methoxyphenol into a three-necked flask, the mass ratio of methacrylic acid, iron formate-modified montmorillonite, N,N-dimethylformamide and p-methoxyphenol is 6:0.2:2:1, stir well, heat to 100°C under reflux condensation, put epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add it dropwise within 6 hours, then after 1 hour of heat preservation reaction, the ring-opening esterification reaction part is completed to obtain an intermediate ring-opening product;

[0104] S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, the concentration of NaOH solution is 30wt%, the addition is completed within 3h, then keep 40℃ for reaction for 1h, then filter while hot, wash the filtrate with 60℃ hot water for 3 times, let it stand and separate, collect the water phase and oil phase respectively, the oil phase is the crude glycidyl methacrylate", test and calculate the yield and purity of the finished glycidyl methacrylate.

[0105] The yield and purity of the finished glycidyl methacrylate of Examples 1-3 were tested and calculated, and compared with Comparative Examples 1-7, they were tabulated as follows.

[0106] Table 1:

[0107] Yield (%) purity(%) Example 1 90.3 99 Example 2 89.5 99 Example 3 89.7 99 Comparative Example 1 86.4 95 Comparative Example 2 87.1 92 Comparative Example 3 84.2 91 Comparative Example 4 82.6 89 Comparative Example 5 87.6 92 Comparative Example 6 88.3 93 Comparative Example 7 86.4 93

[0108] As can be seen from the table, the yields of Examples 1-3 are 90.3%, 89.5% and 89.7% respectively, and the purity reaches 99%, while the yield of Comparative Example 1 is only 86.4% and the purity is only 95%. It can be seen that the acid modification operation changes the adhesion of montmorillonite to iron formate, and the modified montmorillonite loads more iron formate and has better catalytic performance, so the yield and purity are higher.

[0109] The yield of Comparative Example 2 is 87.1% and the purity is 92%. It can be seen that using only iron formate may lead to too fast a reaction rate and unstable temperature, thereby causing a decrease in purity.

[0110] The yield of Comparative Example 3 is 84.2% and the purity is 91%. It can be seen that when acid-modified montmorillonite is used alone without adding iron formate, the catalytic activity of the acid-modified montmorillonite decreases in the middle of the reaction, resulting in a significant decrease in yield and purity.

[0111] The yield of Comparative Example 4 was 82.6% and the purity was 89%. Only montmorillonite was used as a catalyst, and its catalytic performance was lower than that of acid-modified montmorillonite. The yield and purity of the finished glycidyl methacrylate were both reduced.

[0112] The yield of Comparative Example 5 is 87.6% and the purity is 92%. The inhibitor prepared by using only N, N-dimethylformamide silica sol has a lower inhibitory performance than the composite inhibitor silica sol to which N, N-dimethylformamide and p-methoxyphenol are added at the same time. Glycidyl methacrylate polymerizes during the production process, so the yield and purity are also lower than those of the embodiment.

[0113] The yield of Comparative Example 6 is 88.3% and the purity is 93%. The inhibitor prepared by using only the silica sol of p-methoxyphenol has a higher inhibitory performance than N,N-dimethylformamide. Therefore, the yield and purity of Comparative Example 6 are also higher than those of Comparative Example 5, but its purity is still not as good as that of the embodiment. It can be seen that N,N-dimethylformamide and p-methoxyphenol need to be used in coordination.

[0114] The yield of Comparative Example 7 is 86.4% and the purity is 93%. There is no silica sol for sustained release. N,N-dimethylformamide and p-methoxyphenol are directly used, and their purity is difficult to reach the standard of the example. It can be seen that the sustained release effect of silica sol also plays a role in the reaction.

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for the continuous production of glycidyl methacrylate, characterized in that: The steps include: S1: Preparation of iron formate-modified montmorillonite The hydrochloric acid solution and the montmorillonite are mixed, heated, stirred and reacted, then cooled to room temperature, filtered to remove the filtrate, dried the filter residue, crushed and ground to obtain acid-modified montmorillonite, added the acid-modified montmorillonite into deionized water, stirred and dispersed to obtain a suspension, then added iron formate, stirred at a constant temperature to obtain a precipitate, washed with deionized water, then vacuum dried, ground and sieved to obtain iron formate-loaded modified montmorillonite; S2: Preparation of composite inhibitor silica sol Adding silica sol and N, N-dimethylformamide into a reaction bottle, heating and stirring until completely dissolved, to obtain silica sol dissolved with N, N-dimethylformamide, then adding silica sol and p-methoxyphenol into a reaction bottle, heating and stirring until completely dissolved, and pouring into a spherical silica gel mold before it is completely solidified, the injection amount is half of the volume of the spherical silica gel mold, and the other half is injected with silica sol dissolved with N, N-dimethylformamide, and standing and demolding to obtain a composite inhibitor silica sol; S3: Production of crude glycidyl methacrylate Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, stir thoroughly, heat up, drop epichlorohydrin therein, keep warm for reaction, obtain an intermediate ring-opening product, drop NaOH solution, keep warm for reaction, then filter while hot, let stand and separate, collect water phase and oil phase respectively, the oil phase is crude glycidyl methacrylate; S4: Crude glycidyl methacrylate and aqueous phase workup The crude glycidyl methacrylate is centrifuged, and then the solid matter is filtered out to obtain glycidyl methacrylate. The collected water phase is added to a distillation tower, and the water phase enters the distillation tower from the middle. The bottom components are then distilled in a sub-tower to obtain glycidyl methacrylate at the top of the sub-tower. The obtained glycidyl methacrylate is combined to obtain a finished glycidyl methacrylate.

2. The continuous production method of glycidyl methacrylate according to claim 1, characterized in that: Step S1 is to prepare iron formate-loaded modified montmorillonite, comprising the following steps: S1.1: Mix the hydrochloric acid solution and montmorillonite in a volume ratio of 1:12, and heat to 50-55°C, stir and react for 20-24 hours, then cool to room temperature, filter and remove the filtrate, dry the residue at 100-110°C for 12 hours, crush and grind it through a 100-mesh sieve to obtain acid-modified montmorillonite; S1.2: Add acid-modified montmorillonite into deionized water, stir and disperse to obtain a suspension, then add 10% of the total mass of iron formate, stir at a constant temperature of 65°C for 3-4 hours to obtain a precipitate, wash it twice with deionized water, filter out the filtrate, then vacuum dry it for 48 hours, grind it through a 100-mesh sieve, and obtain iron formate-modified montmorillonite.

3. The continuous production method of glycidyl methacrylate according to claim 2, characterized in that: Step S2 is to prepare a composite inhibitor silica sol, comprising the following steps: S2.1: Add silica sol and N,N-dimethylformamide in a mass ratio of (3-4):1 into a reaction bottle, heat to 80-100°C, and stir thoroughly until completely dissolved to obtain silica sol dissolved with N,N-dimethylformamide; S2.2: Add silica sol and p-methoxyphenol in a mass ratio of 15:1 into a reaction bottle, heat to 80-100°C, stir thoroughly until completely dissolved, pour into a spherical silicone mold before it completely solidifies, the injection amount is half of the volume of the spherical silicone mold, and the other half is injected with silica sol dissolved with N,N-dimethylformamide. Let it stand for 24 hours and demold to obtain a composite inhibitor silica sol.

4. The continuous production method of glycidyl methacrylate according to claim 3, characterized in that: Step S3 produces crude glycidyl methacrylate, comprising the following steps: S3.1: Add methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol into a three-necked flask, stir thoroughly, heat to 100-110°C under reflux condensation, place epichlorohydrin accounting for 150% of the total mass of the reaction system into a constant pressure dropping funnel and add dropwise within 5-6 hours, then heat for 1 hour to complete the ring-opening esterification reaction and obtain an intermediate ring-opening product; S3.2: Adjust the water bath temperature to 40℃, slowly add NaOH solution dropwise, complete the addition within 3 hours, then maintain the temperature at 40℃ for 1 hour, then filter while hot, wash the filtrate with 60℃ hot water 2-3 times, let it stand and separate the liquids, collect the aqueous phase and oil phase separately, the oil phase is the crude product of glycidyl methacrylate.

5. The continuous production method of glycidyl methacrylate according to claim 4, characterized in that: Step S4: post-treatment of the crude glycidyl methacrylate and the aqueous phase, comprising the following steps: S4.1: centrifuging the crude glycidyl methacrylate at a centrifugal speed of 800-1000 r / min for 15-20 min, and then filtering to remove solids to obtain glycidyl methacrylate; S4.2: Add the collected water phase to a distillation tower, enter the distillation tower from the middle, evaporate water and epichlorohydrin, set the top pressure of the distillation tower to 6 kPa, the reflux ratio to 1, the feed temperature to 40 ° C, the feed pressure to 120 kPa, the feed flow rate to 500 kg / h, the condenser temperature to 8-12 ° C, the reboiler temperatures to 45 ° C, 85 ° C and 132 ° C respectively, the bottom components are then distilled in the sub-tower, and methacrylic acid glycidyl ester is obtained at the top of the sub-tower, and combined with the methacrylic acid glycidyl ester obtained in step S4.1 to obtain the methacrylic acid glycidyl ester finished product.

6. The continuous production method of glycidyl methacrylate according to claim 2, characterized in that: In step S1.2, the material-liquid ratio of acid-modified montmorillonite to deionized water is 1:10 g / mL.

7. The continuous production method of glycidyl methacrylate according to claim 3, characterized in that: The volume of the spherical silicone mold in step S2.2 is 2 ml.

8. The method for continuous production of glycidyl methacrylate according to claim 4, characterized in that: In step S3.1, the mass ratio of methacrylic acid, iron formate-modified montmorillonite and composite inhibitor silica sol is (6-8): (0.2-0.5): (2-3).

9. The method for continuous production of glycidyl methacrylate according to claim 4, characterized in that: The concentration of the NaOH solution in step S3.2 is 25-30wt%.

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