Continuous preparation method of ethylene glycol dimethacrylate

Abstract

The invention discloses a continuous preparation method of ethylene glycol dimethacrylate, and aims to provide a continuous preparation method of ethylene glycol dimethacrylate, which is high in reaction rate and high in product yield, and is characterized in that methacrylic acid and ethylene glycol are used as raw materials, and continuous production is realized through reactive distillation; the technical scheme comprises the following steps; the method comprises the following steps: 1, filling a reactive distillation tower with a filler, putting methacrylic acid, ethylene glycol, a polymerization inhibitor and sodium hydrogen sulfate into a feeding tank, and uniformly stirring to obtain a reaction raw material; 2, turning on a main power supply, starting a reaction control system, starting a cyclic heating device, and controlling the temperature of the rectifying column to be 100-120 DEG C; starting a circulating condensing device, and controlling the temperature of condensed water to be 0-10 DEG C; 3, starting a peristaltic pump to pump the reaction raw materials in the feeding tank into the reaction rectifying tower, starting an air pump to introduce air, collecting condensate water at the top of the rectifying tower at the beginning of reaction, and obtaining a crude ethylene glycol dimethacrylate product at the bottom of the rectifying tower; and 4, timely transferring water and methacrylic acid collected at the tower top to a tower top liquid storage tank through a pipeline, and timely transferring an ethylene glycol dimethacrylate crude product collected at a tower kettle to an ethylene glycol dimethacrylate crude product storage tank through a pipeline.

Description

Technical Field

[0001] The invention relates to a preparation method of fine chemicals, in particular to a continuous preparation method of ethylene glycol dimethacrylate, belonging to the technical field of fine chemicals. Background Art

[0002] Ethylene glycol dimethacrylate is an important organic compound, widely used in coatings, adhesives, resins and other fields. Currently, the conventional preparation methods of ethylene glycol dimethacrylate mainly include the following:

[0003] 1. Batch direct esterification: ethylene glycol (EG) and methacrylic acid (MAA) react directly over an acidic catalyst to produce EGDMA and water. Because the direct reaction of EG and MAA can be accompanied by side reactions, this method requires strict control of reaction conditions to minimize byproduct formation. Furthermore, the reaction generates a large amount of water, which, if not removed promptly and effectively, can affect the reaction equilibrium and reduce the yield of EGDMA. Furthermore, the presence of water can also promote a reverse reaction, leading to hydrolysis of EGDMA and thus affecting product purity.

[0004] 2. Intermittent transesterification: This method uses ethylene glycol and methyl methacrylate (MMA) to undergo a transesterification reaction in the presence of an alkaline catalyst to produce EGDMA and methanol. This method has relatively harsh reaction conditions, and the use of an alkaline catalyst may cause the product color to darken, affecting its application. In addition, the transesterification method usually requires high temperature and high pressure, which increases production costs and operational difficulty.

[0005] 3. Batch Acid Chloride Alcoholysis: Acryloyl chloride and ethylene glycol react at room temperature to produce EGDMA and hydrogen chloride (HCl). This method produces corrosive HCl gas, which is not only corrosive to equipment but can also be harmful to operators. Therefore, special safety measures and corrosion-resistant materials are required.

[0006] Chinese patent CN 113717048 A discloses a method for preparing ethylene glycol dimethacrylate. The method uses hydroxyethyl methacrylate and methacrylic acid as raw materials. Ethylene glycol dimethacrylate is prepared through a distillation column under the catalysis of phosphotungstic acid, p-toluenesulfonic acid, aminosulfonic acid, concentrated sulfuric acid, and methanesulfonic acid, thereby achieving continuous production. However, this method may cause polymerization during the reaction at higher temperatures, while the reaction efficiency is low at lower temperatures, thereby reducing the yield and increasing the difficulty of purification.

[0007] Therefore, it is particularly necessary to develop an ethylene glycol dimethacrylate with a fast reaction rate and high product yield. Summary of the Invention

[0008] The present invention aims to provide a method for continuously preparing ethylene glycol dimethacrylate with fast reaction rate and high product yield. The method uses methacrylic acid and ethylene glycol as raw materials and realizes continuous production through reactive distillation.

[0009] To this end, the technical solutions provided by the present invention are as follows:

[0010] A continuous preparation method of ethylene glycol dimethacrylate comprises the following steps:

[0011] Step 1: Fill a reactive distillation column with fillers, place methacrylic acid, ethylene glycol, a polymerization inhibitor, and sodium bisulfate in a feed tank and stir them evenly to obtain a reaction raw material;

[0012] The mass ratio of ethylene glycol, methacrylic acid and sodium bisulfate is 500:1600-2400:63-87;

[0013] Step 2: Turn on the main power, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 100-120°C; turn on the circulating condensing device and control the condensed water temperature at 0-10°C;

[0014] Step 3: Turn on the peristaltic pump to pump the reaction raw materials in the feed tank into the reactive distillation tower, turn on the air pump to introduce air, and after the reaction starts, collect condensate water at the top of the distillation tower, and obtain crude ethylene glycol dimethacrylate in the bottom of the distillation tower;

[0015] Step 4: The water and methacrylic acid collected at the top of the tower are promptly transferred to the top liquid storage tank through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank through a pipeline.

[0016] Furthermore, in the above-mentioned continuous preparation method of ethylene glycol dimethacrylate, the mass ratio of ethylene glycol to polymerization inhibitor is 500:6.3-8.7.

[0017] Furthermore, in the above-mentioned continuous preparation method of ethylene glycol dimethacrylate, the air flow rate is 100 to 400 mL / min.

[0018] Furthermore, in the above-mentioned continuous preparation method of ethylene glycol dimethacrylate, the reactive distillation tower is filled with 4mm 316Lθ rings, and the filling mass is 200-250g.

[0019] Furthermore, in the above-mentioned continuous preparation method of ethylene glycol dimethacrylate, the height of the distillation tower is 2 meters; the diameter of the distillation tower is 20 mm to 30 mm.

[0020] Furthermore, in the above-mentioned continuous preparation method of ethylene glycol dimethacrylate, the polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole and phenothiazine.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Compared with the traditional batch synthesis production method, the present invention adopts reactive distillation to carry out the reaction, and the product after the reaction is transferred in time to avoid the influence of side reactions on the product, thereby realizing continuous synthesis production, improving production efficiency, high production efficiency per unit area, small side reactions during the reaction process, and simple post-processing.

[0023] 2. In the reactive distillation technology provided by the present invention, during the esterification process, the water generated in the system is carried out by the air, causing the system to proceed in the direction of generating ethylene glycol dimethacrylate.

[0024] 3. The product collected in the reactor of the reactive distillation device provided by the present invention contains only a small amount of methacrylic acid, catalyst, and polymerization inhibitor in addition to ethylene glycol dimethacrylate. High-purity ethylene glycol dimethacrylate can be obtained through distillation, and the sodium bisulfate catalyst in the reactor can be regenerated by crystallization to achieve catalyst recovery and reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a diagram of the reactive distillation device provided by the present invention.

[0026] Among them: a storage tank 1, a reactive distillation tower 2, a tower top liquid storage tank 3, and an ethylene glycol dimethacrylate crude product storage tank 4.

[0027] Figure 2 It is the gas chromatogram of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The following further describes the claims of the present invention in detail in conjunction with specific implementation methods, but does not constitute any limitation to the present invention. Any limited modifications made by anyone within the scope of the claims of the present invention are still within the scope of protection of the claims of the present invention.

[0029] Unless otherwise specified, the following examples are all routine experimental methods and operating procedures in this field.

[0030] The reaction equation of the technical solution provided by the present invention is shown in Formula 1.

[0031]

[0032] The reactive distillation device used in the technical solution provided by the present invention is Figure 1, including a storage tank 1, which is connected to a reaction distillation tower 2 through a pipeline, and a peristaltic pump is provided between the storage tank 1 and the reaction distillation tower 2 through the pipeline; the top of the reaction distillation tower 2 is connected to an overhead liquid storage tank 3 through a pipeline; the bottom of the reaction distillation tower 2 is connected to an ethylene glycol dimethacrylate crude product storage tank 4 through a pipeline, and a peristaltic pump is provided on the pipeline connecting the top of the reaction distillation tower 2 and the overhead liquid storage tank 3; a peristaltic pump is also provided on the pipeline connecting the bottom of the tower and the ethylene glycol dimethacrylate crude product storage tank 4.

[0033] Reactive distillation tower parameters: tower height 2m; tower diameter 20mm;

[0034] The reactive distillation tower is filled with 200 g of 4 mm 316Lθ ring filler.

[0035] Example 1

[0036] (1) Weigh 500 g of ethylene glycol, 1600 g of methacrylic acid, 63 g of sodium bisulfate, and 6.3 g of hydroquinone, dissolve the sodium bisulfate and hydroquinone in ethylene glycol, add them to the methacrylic acid, stir and mix, and then load them into the storage tank 1 at the feed port of the reactive distillation device;

[0037] (2) Turn on the main power supply, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column of the reaction distillation tower 2 at 100°C; turn on the circulating condensing device and control the condensed water temperature at 5°C;

[0038] (3) Turn on the peristaltic pump to continuously pump the raw materials in the feed storage tank into the reactive distillation tower 2, control the feed rate of the raw materials (ethylene glycol, methacrylic acid, sodium bisulfate and hydroquinone) to 2g / min, turn on the air pump to introduce air, and control the air rate to 200m / min (the gas flow rate is controlled by a gas flow meter). After the reaction is completed, the pale yellow liquid collected in the tower bottom is the crude ester. The product detection chromatogram is shown in FIG. Figure 1 ;

[0039] (4) The water and methacrylic acid collected at the top of the tower are promptly transferred to the tower top liquid storage tank 3 through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank 4 through a pipeline; deionized water is added to the crude ester, mixed and then placed in a separatory funnel for static separation, and after obtaining the aqueous phase, the aqueous phase is evaporated and crystallized to obtain sodium bisulfate, which is reused.

[0040] Example 2

[0041] (1) Weigh 500 g of ethylene glycol, 2000 g of methacrylic acid, 75 g of sodium bisulfate, and 7.5 g of hydroquinone, dissolve the sodium bisulfate and hydroquinone in ethylene glycol, add them to the methacrylic acid, stir and mix, and then load them into the storage tank 1 at the feed port of the reactive distillation device;

[0042] (2) Turn on the main power supply, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 110°C; turn on the circulating condensing device and control the condensed water temperature at 5°C;

[0043] (3) Turn on the peristaltic pump to continuously pump the raw materials in the feed storage tank into the reactive distillation tower 2, control the feed rate of the raw materials (ethylene glycol, methacrylic acid, sodium bisulfate and hydroquinone) to 2 g / min, turn on the air pump to introduce air, and control the air rate to 200 m / min (the gas flow rate is controlled by a gas flow meter). After the reaction is completed, the pale yellow liquid collected in the tower bottom is the crude ester;

[0044] (4) The water and methacrylic acid collected at the top of the tower are promptly transferred to the tower top liquid storage tank 3 through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank 4 through a pipeline; deionized water is added to the crude ester, mixed and then placed in a separatory funnel for static separation, and after obtaining the aqueous phase, the aqueous phase is evaporated and crystallized to obtain sodium bisulfate, which is reused.

[0045] Example 3

[0046] (1) Weigh 500 g of ethylene glycol, 2400 g of methacrylic acid, 87 g of sodium bisulfate, and 8.7 g of hydroquinone, dissolve the sodium bisulfate and hydroquinone in ethylene glycol, add them to the methacrylic acid, stir and mix, and then load them into the storage tank 1 at the feed port of the reactive distillation device;

[0047] (2) Turn on the main power supply, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 120°C; turn on the circulating condensing device and control the condensed water temperature at 5°C;

[0048] (3) Turn on the peristaltic pump to continuously pump the raw materials in the feed storage tank into the reactive distillation tower 2, control the feed rate of the raw materials (ethylene glycol, methacrylic acid, sodium bisulfate and hydroquinone) to 2 g / min, turn on the air pump to introduce air, and control the air rate to 200 m / min (the gas flow rate is controlled by a gas flow meter). After the reaction is completed, the pale yellow liquid collected in the tower bottom is the crude ester;

[0049] (4) The water and methacrylic acid collected at the top of the tower are promptly transferred to the tower top liquid storage tank 3 through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank 4 through a pipeline; deionized water is added to the crude ester, mixed and then placed in a separatory funnel for static separation, and after obtaining the aqueous phase, the aqueous phase is evaporated and crystallized to obtain sodium bisulfate, which is reused.

[0050] Example 4

[0051] (1) Weigh 500 g of ethylene glycol, 2000 g of methacrylic acid, 75 g of sodium bisulfate, and 7.5 g of hydroquinone, dissolve the sodium bisulfate and hydroquinone in ethylene glycol, add them to the methacrylic acid, stir and mix, and then load them into the storage tank 1 at the feed port of the reactive distillation device;

[0052] (2) Turn on the main power supply, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 110°C; turn on the circulating condensing device and control the condensed water temperature at 5°C;

[0053] (3) Turn on the peristaltic pump to continuously pump the raw materials in the feed storage tank into the reactive distillation tower 2, control the feed rate of the raw materials (ethylene glycol, methacrylic acid, sodium bisulfate and hydroquinone) to 2 g / min, turn on the air pump to introduce air, and control the air rate to 200 m / min (the gas flow rate is controlled by a gas flow meter). After the reaction is completed, the pale yellow liquid collected in the tower bottom is the crude ester;

[0054] (4) The water and methacrylic acid collected at the top of the tower are promptly transferred to the tower top liquid storage tank 3 through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank 4 through a pipeline; deionized water is added to the crude ester, mixed and then placed in a separatory funnel for static separation, and after obtaining the aqueous phase, the aqueous phase is evaporated and crystallized to obtain sodium bisulfate, which is reused.

[0055] Example 5

[0056] (1) Weigh 500 g of ethylene glycol, 2000 g of methacrylic acid, 75 g of sodium bisulfate, and 7.5 g of hydroquinone, dissolve the sodium bisulfate and hydroquinone in ethylene glycol, add them to the methacrylic acid, stir and mix, and then load them into the storage tank 1 at the feed port of the reactive distillation device;

[0057] (2) Turn on the main power supply, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 110°C; turn on the circulating condensing device and control the condensed water temperature at 5°C;

[0058] (3) Turn on the peristaltic pump to continuously pump the raw materials in the feed storage tank into the reactive distillation tower 2, control the feed rate of the raw materials (ethylene glycol, methacrylic acid, sodium bisulfate and hydroquinone) to 2 g / min, turn on the air pump to introduce air, and control the air rate to 200 m / min (the gas flow rate is controlled by a gas flow meter). After the reaction is completed, the pale yellow liquid collected in the tower bottom is the crude ester;

[0059] (4) The water and methacrylic acid collected at the top of the tower are promptly transferred to the tower top liquid storage tank 3 through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank 4 through a pipeline; deionized water is added to the crude ester, mixed and then placed in a separatory funnel for static separation, and after obtaining the aqueous phase, the aqueous phase is evaporated and crystallized to obtain sodium bisulfate, which is reused.

Claims

1. A continuous preparation method of ethylene glycol dimethacrylate, characterized in that: The following steps are included: Step 1: Fill a reactive distillation column with fillers, place methacrylic acid, ethylene glycol, a polymerization inhibitor, and sodium bisulfate in a feed tank and stir them evenly to obtain a reaction raw material; The mass ratio of ethylene glycol, methacrylic acid and sodium bisulfate is 500:1600-2400:63-87; Step 2: Turn on the main power, start the reaction control system, turn on the circulating heating device, and control the temperature of the distillation column at 100-120°C; turn on the circulating condensing device and control the condensed water temperature at 0-10°C; Step 3: Turn on the peristaltic pump to pump the reaction raw materials in the feed tank into the reactive distillation tower, turn on the air pump to introduce air, and after the reaction starts, collect condensate water at the top of the distillation tower, and obtain crude ethylene glycol dimethacrylate in the bottom of the distillation tower; Step 4: The water and methacrylic acid collected at the top of the tower are promptly transferred to the top liquid storage tank through a pipeline, and the crude ethylene glycol dimethacrylate collected at the bottom of the tower is promptly transferred to the crude ethylene glycol dimethacrylate storage tank through a pipeline.

2. The continuous preparation method of ethylene glycol dimethacrylate according to claim 1, wherein The mass ratio of the ethylene glycol to the polymerization inhibitor is 500:6.3-8.

7.

3. The continuous preparation method of ethylene glycol dimethacrylate according to claim 1, characterized in that: The air flow rate is 100-400 mL / min.

4. The continuous preparation method of ethylene glycol dimethacrylate according to claim 1, characterized in that: The reactive distillation tower is filled with 4mm 316Lθ rings, with a filling mass of 200-250g.

5. The continuous preparation method of ethylene glycol dimethacrylate according to claim 1, characterized in that: The distillation tower has a height of 2 meters and a diameter of 20 mm to 30 mm.

6. The continuous preparation method of ethylene glycol dimethacrylate according to claim 1, characterized in that: The polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole and phenothiazine.

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