JP2015044746A - Method for continuously producing glycidyl (meth)acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably synthesizing a glycidyl (meth)acrylate with high yield and good productivity.SOLUTION: There is provided a method for continuously producing a glycidyl (meth)acrylate by reacting an alkali metal salt of a (meth)acrylic acid and epichlorohydrin in the presence of a catalyst and a polymerization inhibitor. The conversion ratio based on the alkali metal salt of a (meth)acrylic acid is maintained at 50% or more.

Description

  The present invention relates to a continuous production method of glycidyl (meth) acrylate.

  Several synthesis methods using batches of glycidyl (meth) acrylate are known (Patent Documents 1 and 2). In Patent Document 1, glycidyl methacrylate is produced by reacting an alkali metal salt of methacrylic acid and epichlorohydrin in the presence of a quaternary ammonium salt and a polymerization inhibitor while adjusting the water concentration in the reaction system to 600 to 1600 ppm. A method of performing is disclosed. Patent Document 2 discloses a method for producing glycidyl (meth) acrylate by dehydrochlorination after reacting (meth) acrylic acid and epichlorohydrin using a quaternary ammonium salt as a catalyst.

  Moreover, the technique described in patent document 3 and 4 is known as a technique regarding the continuous synthesis method of glycidyl (meth) acrylate. Patent Documents 3 and 4 disclose a method for continuously producing glycidyl (meth) acrylate using a basic ion exchange resin, and correspond to the continuous production method of Patent Document 2.

Japanese Patent Laid-Open No. 7-2818 Japanese Patent Laid-Open No. 7-118251 GB 1155543 US3335156

  However, in the method described in Patent Document 1, glycidyl (meth) acrylate can be produced with high yield. However, since it is a slurry reaction, it is difficult to control for stable production. The method described in Patent Document 2 is a liquid reaction and easy to handle, but only a low yield can be obtained. In the methods described in Patent Documents 3 and 4, the yield of glycidyl (meth) acrylate is low, and the basic ion exchange resin used is expensive and has low thermal stability, resulting in high catalyst costs.

  Therefore, it is desired to produce glycidyl (meth) acrylate with high yield and good productivity. Moreover, it is desired that stable production in a slurry reaction becomes possible.

  Accordingly, an object of the present invention is to provide a method for producing glycidyl (meth) acrylate that can be stably synthesized with high yield and good productivity.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above-described object can be achieved by maintaining the conversion rate at 50% or more in continuous production. The invention has been completed.

  The present invention relates to a method for producing glycidyl (meth) acrylate by reacting an alkali metal (meth) acrylate with epichlorohydrin in the presence of a catalyst and a polymerization inhibitor. The present invention relates to a process characterized in that glycidyl (meth) acrylate is continuously produced while maintaining a conversion rate based on metal salt at 50% or more.

  According to the present invention, it is possible to stably maintain a slurry reaction in a complete mixing type apparatus, and solids do not adhere to the inner wall of the apparatus or settle as a lump. A continuous production method of glycidyl (meth) acrylate with high yield and high productivity can be provided.

Hereafter, the detail of each process of the method concerning this invention is shown.

  (Meth) acrylic acid indicates methacrylic acid or acrylic acid.

[Reaction process]
In the present invention, glycidyl (meth) acrylate is synthesized by reaction of epichlorohydrin and an alkali metal (meth) acrylate. The (meth) acrylic acid alkali metal salt is produced by a reaction with (meth) acrylic acid and an alkali metal hydroxide.

  In the present invention, (meth) acrylic acid, alkali metal hydroxide, catalyst, polymerization inhibitor and epichlorohydrin are continuously supplied. At this time, each may be supplied separately, or may be supplied after mixing two or more.

  For example, if an aqueous solution of (meth) acrylic acid and an alkali metal hydroxide is separately supplied to the reaction apparatus, an (meth) acrylic acid alkali metal salt is generated inside the reaction apparatus. Alternatively, both may be mixed in advance and supplied as an aqueous solution of an alkali metal (meth) acrylate by a neutralization reaction.

The catalyst may be supplied after being dissolved in an aqueous solution of an alkali metal hydroxide, or may be supplied after being dissolved in an aqueous solution of an alkali metal (meth) acrylate. The polymerization inhibitor may be supplied after being dissolved in epichlorohydrin.
Although it does not specifically limit as an alkali metal hydroxide, Sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. are used. These may use only 1 type and may use 2 or more types together.

  The mixing ratio of (meth) acrylic acid and alkali metal hydroxide is most preferably equimolar from the viewpoint of suppressing side reactions. In the present invention, the alkali metal hydroxide is added to 1 mol of (meth) acrylic acid. It can be used in the range of 0.9 to 1.1 mol, more preferably 0.95 to 1.05 mol, and still more preferably 0.97 to 1.03 mol.

  By setting the ratio of the alkali metal hydroxide to (meth) acrylic acid to 0.9 or more, the yield based on (meth) acrylic acid can be improved. Moreover, a side reaction can be suppressed by making the ratio of the alkali metal hydroxide with respect to (meth) acrylic acid 1.1 or less.

  In the case of preparing an aqueous solution of an alkali metal (meth) acrylate in advance, the neutralization reaction temperature between (meth) acrylic acid and the alkali metal hydroxide is −10 ° C. to 80 ° C. from the viewpoint of polymerization inhibition and cooling efficiency. ° C is preferred, 0 ° C to 60 ° C is more preferred, and 5 ° C to 50 ° C is even more preferred.

  Cooling energy can be suppressed by performing the neutralization reaction temperature at −10 ° C. or higher. Moreover, the polymerization of (meth) acrylic acid can be suppressed by performing the neutralization reaction temperature at 80 ° C. or lower.

  When performing this neutralization reaction, a polymerization inhibitor may be added to suppress polymerization. The polymerization inhibitor used here may be the same type as the polymerization inhibitor used for the reaction of epichlorohydrin and (meth) acrylic acid alkali metal salt described below.

  The reaction between epichlorohydrin and alkali metal (meth) acrylate is carried out in the presence of a catalyst. As the catalyst, a known catalyst used in the epoxy addition reaction can be used, and for example, a quaternary ammonium salt can be used. Tetraalkylammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide can be used as the quaternary ammonium salt. These may use only 1 type and may use 2 or more types together.

  The amount of the catalyst used in the reaction between epichlorohydrin and the alkali metal (meth) acrylate is preferably 0.0001 to 0.1 mol with respect to 1 mol of the (meth) acrylic acid alkali metal salt. -0.05 mol is more preferable, and 0.001-0.03 mol is still more preferable. By setting the amount of the catalyst to 0.0001 mol or more with respect to 1 mol of the alkali metal (meth) acrylate, a sufficient reaction rate can be obtained. Moreover, the production | generation of a by-product can be suppressed by making the quantity of a catalyst into 0.1 mol or less with respect to 1 mol of (meth) acrylic-acid alkali metal salts, and it becomes a catalyst cost reduction.

  In the present invention, since glycidyl (meth) acrylate is continuously produced, epichlorohydrin and (meth) acrylic acid alkali metal salt or (meth) acrylic acid so that the raw material and the catalyst are maintained in the above ratio. And an alkali metal hydroxide may be added as appropriate.

The ratio of epichlorohydrin and (meth) acrylic acid alkali metal salt in the reaction solution is that the (meth) acrylic acid alkali metal salt remains in the reaction system and the conversion rate decreases, In order to destabilize the synthesis state, it is preferable to maintain the number of moles of epichlorohydrin with respect to the (meth) acrylic acid alkali metal salt in the reaction solution at 1 or more. The number of moles of epichlorohydrin with respect to the (meth) acrylic acid alkali metal salt in the reaction solution,
It is more preferable to set it as 1-50, and it is still more preferable to set it as 2-30.

  The method for maintaining the ratio is not particularly limited. For example, the reaction proceeds and epichlorohydrin and (meth) acrylic acid alkali metal salt may be added so as to have the above ratio.

  In the reaction between epichlorohydrin and alkali metal (meth) acrylate, a polymerization inhibitor is used to suppress polymerization. A known polymerization inhibitor can be used as the polymerization inhibitor. For example, phenols such as hydroquinone and paramethoxyphenol, amines such as phenothiazine, N-oxyls such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (HO-TEMPO), etc. Can be used. These may use only 1 type and may use 2 or more types together. In order to prevent polymerization, it is preferable to supply oxygen or air during the reaction.

  The reaction temperature in the reaction between epichlorohydrin and the alkali metal (meth) acrylate can be selected according to the amount of catalyst used. The reaction temperature is preferably 40 to 150 ° C, more preferably 50 to 140 ° C, and still more preferably 60 to 120 ° C. By setting the reaction temperature to 40 ° C. or higher, a sufficient reaction rate can be obtained. Moreover, the production | generation of a by-product can be suppressed by making reaction temperature 150 degrees C or less, and superposition | polymerization can also be suppressed.

  The amount of the polymerization inhibitor used in the reaction between epichlorohydrin and the alkali metal (meth) acrylate is preferably 10 to 10,000 ppm by mass, and preferably 30 to 5000 ppm by mass with respect to the alkali metal (meth) acrylate. More preferred is 50 to 2000 ppm by mass. By setting the amount of the polymerization inhibitor to 10 mass ppm or more, the polymerization can be sufficiently suppressed. In addition, by setting the amount of the polymerization inhibitor to 10000 mass ppm or less, it is possible to prevent quality deterioration due to coloring of the product and the like, and it is possible to reduce the cost.

  In the present invention, since glycidyl (meth) acrylate is continuously produced, epichlorohydrin and (meth) acrylic acid alkali metal salt or (meth) acrylic acid so that the raw material and the catalyst are maintained in the above ratio. And an alkali metal hydroxide may be added as appropriate.

  The reaction between the alkali metal (meth) acrylate and epichlorohydrin is a slurry reaction, and when a small amount of the aqueous solution of alkali metal (meth) acrylate is added to epichlorohydrin, the viscosity increases extremely. It became clear that the reaction was difficult to control due to adhesion to the inner wall of the device and sedimentation of the mass.

  Therefore, in the present invention, it has been found that the slurry mixing state can be stabilized by maintaining the reaction conversion rate above a certain level in the continuous synthesis method as a reaction control means. That is, when the conversion rate based on the alkali metal salt of (meth) acrylic acid is 50% or more, the slurry mixed state can be stabilized and operated. Since the slurry mixing state becomes better as the conversion rate is increased, the conversion rate is more preferably 60% or more, and further preferably 70% or more.

  In the present invention, the method for maintaining the conversion rate above a certain value is not particularly limited, and any method can be used as long as the conversion rate can be maintained above a certain value. For example, the conversion rate can be maintained by adding the raw material while extracting the product glycidyl (meth) acrylate from the apparatus.

  Moreover, since a by-product will increase when there is much water content in a reaction liquid (slurry), it is so preferable that the water content in a reaction liquid is small. In the present invention, since an aqueous alkali metal hydroxide solution is used, a large amount of water is present in the reaction solution. For example, by increasing the azeotropic dehydration rate with epichlorohydrin, the reaction solution It is sufficient to reduce the amount of water and maintain it.

  The water content in the reaction solution is practically 0.001% by mass or more from the viewpoint of energy efficiency and productivity, more preferably 0.005% by mass or more, and more preferably 0.01% by mass or more. From the viewpoint of selectivity and synthesis stabilization, it is preferably maintained at 1.0% by mass or less, more preferably 0.7% by mass or less, and more preferably less than 0.5% by mass.

The aqueous solution of alkali metal (meth) acrylate may be supplied to the tower at the top of the reactor. However, the salt is precipitated by azeotropic dehydration with epichlorohydrin in the tower and adheres to the reactor. Direct injection is preferred.
In the present invention, the extracted reaction solution can be further kept at a predetermined temperature for a certain period of time to be aged, thereby increasing the reaction conversion rate. The aging conditions are not particularly limited, and can be appropriately selected according to the concentration of glycidyl (meth) acrylate. For example, the aging temperature can be 70 to 120 ° C, preferably 80 to 115 ° C, more preferably 85 to 110 ° C. The aging time can be 0.01 to 10 hours, preferably 0.1 to 5 hours, more preferably 0.2 to 3 hours.

  Thus, an apparatus for performing aging can be attached. In this case, the accompanying reaction apparatus may use a plurality of tank reactors in parallel or in series, or may be a piston flow type reaction apparatus.

[Washing process or filtration process]
In the present invention, glycidyl (meth) acrylate, which is a reactive organism, is extracted from the reaction apparatus, and the extracted reaction solution can be washed as necessary.

In the extracted reaction liquid, there are alkali metal chloride, catalyst, excess epichlorohydrin, by-product and the like in addition to glycidyl (meth) acrylate. By washing the reaction solution with washing water, the alkali metal chloride, the catalyst and the specific by-product can be dissolved in the aqueous layer and separated and removed. Alternatively, by filtering the reaction solution, it is possible to remove by-produced alkali metal chloride and unreacted (meth) acrylic acid alkali metal salt.
As the washing water used for washing, an aqueous solution in which an alkaline compound is dissolved in water can be used. Although it does not specifically limit as an alkaline compound, For example, an alkali metal hydroxide, an alkali metal carbonate, an alkali metal hydrogencarbonate etc. are mentioned. Specific examples include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like. These may use only 1 type and may use 2 or more types together.

  The amount of the alkaline compound contained in the washing water is preferably 0 parts by mass or more and 50 parts by mass or less, more preferably 0.1 parts by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of water constituting the washing water. 0.2 mass part or more and 20 mass parts or less are more preferable. When the amount of the alkaline compound is within the above range, generation of by-products can be sufficiently suppressed.

  The amount of washing water used in the washing step is preferably an amount that can sufficiently dissolve the alkali metal chloride and the catalyst. Specifically, the amount of washing water is neutralized after the reaction of alkali metal hydroxide or (meth) acrylic acid and epichlorohydrin added in neutralization of (meth) acrylic acid and alkali metal hydroxide. 160 g or more and 2000 g or less are preferable with respect to 1 mol of the alkali compound added when washing with water, and 180 g or more and 1500 g or less are more preferable. When the amount of the washing water is 160 g or more, the alkali metal chloride and the catalyst can be sufficiently dissolved. Moreover, productivity improves by the quantity of washing water being 2000 g or less.

  The washing method is not particularly limited as long as glycidyl (meth) acrylate can be sufficiently washed. For example, what is necessary is just to stir. The reaction liquid and washing water can be sufficiently stirred and mixed using a stirrer equipped with a stirring blade. The stirring time is not particularly limited, and can be, for example, 3 minutes or more and 60 minutes or less.

  The reaction solution and the washing water are stirred and mixed, and then allowed to stand to separate into a washing organic layer and an aqueous layer. The washed organic layer can be purified in the next distillation step.

  The water washing process may be a batch type or a continuous type. In the case of the continuous type, a known method such as performing countercurrent extraction using an extraction tower can be used.

  For the filtration, a known method such as a pressurization method or a cross flow method can be used.

[Distillation process]
In this invention, the process of distilling the organic layer after washing | cleaning or filtration can be included. Glycidyl (meth) acrylate can be obtained by distilling the organic layer after washing or filtration. The organic layer after washing or filtration can be distilled by a known method. In order to obtain high-purity glycidyl (meth) acrylate, it is preferable to perform rectification using a column. Distillation can be carried out either batchwise or continuously. However, when the reaction step is continuous, it is preferable that the washing or filtration step and the distillation step are also continuous, so that the process is more productive.

  Since glycidyl (meth) acrylate is a polymerizable monomer, polymerization can be suppressed by performing distillation at a lower temperature under reduced pressure. From the above viewpoint, the temperature of the distillation pot is preferably 160 ° C. or less, and more preferably 150 ° C. or less. On the other hand, from the viewpoint of distillation efficiency, the temperature of the distillation pot is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. Further, the degree of reduced pressure is preferably 0.1 kPa or more, more preferably 0.5 kPa or more, from the viewpoint of the reduced pressure limit. On the other hand, from the viewpoint of lowering the temperature, 50 kPa or less is preferable, and 30 kPa or less is more preferable.

  In order to suppress the polymerization, a known polymerization inhibitor can be fed into the distillation kettle and the column. As the polymerization inhibitor, for example, phenols such as hydroquinone and paramethoxyphenol, and N-oxyls such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (HO-TEMPO) are used. can do. These may use only 1 type and may use 2 or more types together. In order to prevent polymerization, it is preferable to bubble oxygen or air during distillation.

  A well-known method can be used for the rectification operation using a column. A known apparatus such as a tray or a packed tower using a packing material can be used for the tower. In the distillation operation, the purity can be increased by controlling the distillation ratio. Specifically, from the viewpoint of ensuring purity and productivity, the return ratio is preferably in the range of 0.1 to 10, and more preferably in the range of 0.3 to 3.

  In continuous distillation, the organic layer after washing or filtration is continuously distilled. In order to recover epichlorohydrin as a raw material, low boiling point substances are separated while continuously supplying the organic layer after washing or filtration to the tower. Among the separated low-boiling substances, a component containing 90% by mass or more of epichlorohydrin can be recovered and used as a reaction raw material. The component containing less than 90% by mass of epichlorohydrin contains a large amount of glycidol. By supplying it to the cleaning process, glycidol is removed into the aqueous phase, and epichlorohydrin and glycidyl (meth) acrylate are recovered in the organic layer. it can.

  A liquid containing glycidyl (meth) acrylate having a high boiling point is concentrated at the bottom of the column. This is fed to the next column to distill glycidyl (meth) acrylate. A low boiling point removal tower may be provided between these steps to remove low boiling point impurities.

  The temperature of the distillation pot in these distillation steps is preferably 160 ° C. or less, and more preferably 150 ° C. or less from the viewpoint of inhibiting polymerization. On the other hand, from the viewpoint of distillation efficiency, the temperature of the distillation pot is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. Further, the degree of reduced pressure is preferably 0.1 kPa or more, more preferably 0.5 kPa or more, from the viewpoint of the reduced pressure limit. On the other hand, from the viewpoint of lowering the temperature, 50 kPa or less is preferable, and 30 kPa or less is more preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. Gas chromatography (GC) analysis was used for the analysis of each compound in Examples and Comparative Examples.
(Example 1)
In a 1 L 5-neck flask equipped with a 10-stage older show, thermometer, air inlet tube, and raw material supply line, 533.7 g (5.77 mol) of epichlorohydrin and 3.83 g (0.036 mol) of sodium methacrylate were added. ), Glycidyl methacrylate 255.9 g (1.80 mol), sodium chloride 105.21 g (1.80 mol), tetramethylammonium chloride 0.581 g (0.005 mol), and benzoyl ester of HO-TEMPO as a polymerization inhibitor 0. 034 g was added.

  The epichlorohydrin heated to the upper part of the tower was cooled through a cooling pipe and allowed to stand for separation. When water was also raised to the upper part of the tower, water was extracted. While reducing the pressure inside the reaction system to 33.3 kPa, supplying air at 10 mL / min, starting heating and stirring at a bath temperature of 115 ° C., initially refluxing epichlorohydrin, and epichlorohydrin during the following continuous reaction. An azeotrope of hydrin and water was refluxed. The conversion rate before starting the continuous reaction was 98%, and the water content in the reaction solution was 60 ppm.

  In this state, 48.5 g (0.2 mol as sodium methacrylate) of a 43.9 mass% sodium methacrylate aqueous solution in which 0.116 g (0.001 mol) of tetramethylammonium chloride was dissolved, and HO— as a polymerization inhibitor. Epichlorohydrin (53.4 g, 0.578 mol) in which 0.0034 g of TEMPO benzoyl ester was dissolved was fed over 1 hour and allowed to react continuously. At the same time, a part of the reaction solution was overflowed from the upper part of the flask and extracted. During the reaction, the stirring state of the slurry was good, and no poor stirring was observed. The water content of the reaction solution in the flask during the dropwise addition of the aqueous sodium methacrylate solution was 198 ppm.

  When the reaction solution after completion of the continuous reaction was filtered and subjected to GC analysis, the GC area percentage excluding epichlorohydrin was 96.9% for glycidyl methacrylate and 1.451% for the total amount of high boiling impurities. The conversion rate calculated from the residual sodium methacrylate at this time was 98.7%, and the water content was 173 ppm.

(Comparative Example 1: Example of batch reaction (starting from 0% conversion))
In Example 1, epichlorohydrin, tetramethylammonium chloride, and a benzoyl ester of HO-TEMPO were charged without adding glycidyl methacrylate and sodium chloride at the initial charging, and the same operation was performed thereafter. As soon as the sodium methacrylate aqueous solution began to be dropped, the properties of the reaction slurry deteriorated, and there was no fluidity, so that a mass of sodium methacrylate adhered to the inner wall of the flask and control became impossible.

(Comparative Example 2: An example in which the conversion rate is low and the amount of water in the reaction solution is large)
In Example 1, 59.3 g (0.64 mol) of epichlorohydrin added initially, 0.43 g (0.004 mol) of sodium methacrylate, 28.4 g (0.20 mol) of glycidyl methacrylate, chloride 11.7 g (0.20 mol) of sodium, 0.116 g (0.001 mol) of tetramethylammonium chloride, 0.0038 g of benzoyl ester of HO-TEMPO as a polymerization inhibitor, and 0.581 g of tetramethylammonium chloride added dropwise ( 436.5 g of sodium methacrylate aqueous solution in which 0.005 mol) was dissolved (1.8 mol as sodium methacrylate), and 480.6 g of epichlorohydrin in which 0.0306 g of benzoyl ester of HO-TEMPO was dissolved as a polymerization inhibitor. 5.202Mol) and then, except that raised the drip rate 10 times, the reaction was performed under the same conditions. The properties of the reaction liquid slurry deteriorated, and there was no fluidity at all, and a mass of sodium methacrylate adhered to the inner wall of the flask, making it difficult to control. The water content in the reaction solution was observed to be 5260 ppm or more, and the conversion rate was 15%.

  The glycidyl (meth) acrylate produced by the method according to the present invention can be used for various paints, adhesives, pressure-sensitive adhesives, various reactive monomers, and the like.

Claims (6)

In the method for producing glycidyl (meth) acrylate by reacting an alkali metal (meth) acrylate with epichlorohydrin in the presence of a catalyst and a polymerization inhibitor,
A method characterized by continuously producing glycidyl (meth) acrylate while maintaining a conversion rate based on alkali metal (meth) acrylate at 50% or more.   The method according to claim 1, wherein the concentration of water in the reaction liquid is maintained at 1% by mass or less.   3. The method according to claim 1, wherein the molar ratio of epichlorohydrin to alkali metal (meth) acrylate is maintained at 1 or more.   The method in any one of Claims 1-3 including the process of further aging the reaction liquid containing the obtained glycidyl (meth) acrylate.   The method in any one of Claims 1-4 which further includes the process of wash | cleaning and / or distilling the reaction liquid containing the obtained glycidyl (meth) acrylate.   The method according to claim 1, wherein epichlorohydrin contained in the solution distilled off by the method according to claim 5 is reused.