JPH07149749A - Method for purifying glycidyl methacrylate - Google Patents

Abstract

PURPOSE:To provide a purification method for obtaining high-purity glycidyl methacrylate(GMA) in a high yield from crude GMA obtained by ester interchange reaction of glycidol with methyl methacrylate while preventing polymerization of the crude GMA. CONSTITUTION:In purifying crude GMA produced by ester interchange reaction of glycidol with methyl methacrylate in the presence of a basic catalyst, preferably tert.-amine, especially triethylamine, the crude GMA is treated with 0.1-10wt.% of a montmorillonite-based mineral (e.g. active clay or acidic clay) before carrying out distillation purification to absorb the remaining basic catalyst and the montmorillonite-based mineral is separated by operation such as filtration or centrifugal separation and the crude GMA is distilled under 1-30 torr. pressure in the presence of a polymerization inhibitor to provide the objective high-purity GMA.

Description

Detailed Description of the Invention

[0001]

The present invention relates to glycidol (hereinafter,
The present invention relates to a method for purifying glycidyl methacrylate (hereinafter, referred to as GMA) produced by a transesterification reaction between GD) and methyl methacrylate (hereinafter, referred to as MMA).

GMA has a highly reactive double bond and an epoxy group in the molecule and is used as a resin raw material for paints.

[0003]

2. Description of the Related Art Many methods for producing GMA by transesterification of GD and MMA have been known so far, and generally, by-produced methanol is distilled into a system in the presence of a basic catalyst. The reaction is performed while removing it to the outside.

After completion of the reaction, the catalyst used in the reaction is GM
Filtration before purification of A (Japanese Patent Publication No. 53-6133 / Degussa,
Japanese Examined Patent Publication No. 61-43351 / Nippon Yushi) and water washing (JP-A-5
5 to 105676 / Mitsui Toatsu) and the like to remove it outside the system. It is very difficult to completely remove the catalyst before the purification of the crude GMA by the above-mentioned filtration or washing with water, and since the catalyst still remains in the crude GMA after the treatment, there remains a problem that it is easily polymerized during the distillation purification. ing. Further, there is a problem that washing with water causes a large loss of GMA and recovered MMA. Further, when amines are used as a catalyst for the reaction (Japanese Patent Application Laid-Open No. 55-94379 / Daicel Chemical Industries), amines are better than GMA. Due to its low boiling point, it can be removed out of the system by distillation before GMA. However, a very small amount of amine undergoes a side reaction and remains as a high boiling point compound on the kettle side during GMA purification.
There is a problem that polymerization is likely to occur during purification of crude GMA.

[0005]

It is an object of the present invention to prevent the polymerization of crude GMA which is very easy to polymerize during distillation and purification in a method for producing GMA by transesterification of GD and MMA, and to obtain a high yield and high purity. It is to develop a method for obtaining the product GMA.

[0006]

That is, the present invention is
“In a method for purifying glycidyl methacrylate produced by transesterification of glycidol and methyl methacrylate in the presence of a basic catalyst, methacrylic acid characterized by being treated with a montmorillonite-based mineral before purification and then purified. Purification method of glycidyl acid salt ".

Examples of the basic catalyst used in the present invention include carboxylic acid salts of alkali metals and alkaline earth metals such as lithium acetate, potassium acetate and magnesium acetate, which are usually used as basic catalysts, triethylamine, tributylamine, dibutylamine and the like. The above amines may be mentioned, but other basic catalysts may be used for carrying out the present invention. Further, the production of GMA by the transesterification reaction of GD and MMA of the present invention can be carried out by a usual reactive distillation in which methanol produced in the reaction is removed from the top of the column. In addition, even if a solvent such as n-hexane or cyclohexane is used as an azeotropic agent for methanol, there is no problem in carrying out the present invention.

[0008] Next, after the production of methanol is eliminated or almost eliminated, deMMA, deazeotropic agent, and decatalyst are optionally operated. The polymerization during this operation depends on the degree of reduced pressure. It can be carried out without any problems if it is carried out under the conditions that are usually carried out. In addition, when an insoluble basic catalyst is used, usually before deMMA (in some cases, deMM
After A), it is removed from the distillation system by an operation such as filtration, but some dissolved basic catalyst is still present in the crude GMA.

[0009] Usually, the problem is that the raw GMA after deMMA (of course MMA is also included) to the product GM is used.
This is to prevent polymerization in the step of separating A by distillation.

As a result of a detailed study by the present inventors, after treatment with a montmorillonite-based mineral and removal to the outside of the system by filtration or centrifugation, the basic catalyst is adsorbed and removed, and it is extremely difficult to polymerize during distillation purification. Became clear.

The montmorillonite mineral used in the present invention can be selected from the commercially available products such as activated clay and acid clay. For example, Nissan Gardler
Co., Ltd. K series catalyst KSF, KSF / O, KP
10, KS and the like. Further, the montmorillonite-based mineral has an ion-exchange ability, and may be used in the proton form, or may be used as an alkali metal (lithium, sodium, potassium,
Rubidium and the like), alkaline earth metals (beryllium, magnesium, calcium, strontium, etc.), and rare earth metals (lanthanum, cerium, praseodymium, neodymium, etc.) may be used in a form exchanged with ions.

The montmorillonite mineral used for the treatment of the crude GMA needs to be determined according to the amount of the residual base in the crude GMA, but normally 0.1 to 10 wt% is preferably used with respect to the crude GMA. Excessive use of the montmorillonite mineral is not preferable because the separation from the treated crude GMA becomes complicated and the usage rate increases.

The montmorillonite mineral may be added as it is while stirring the untreated crude GMA while stirring with a stirrer. Further, the montmorillonite mineral may be charged in several times, or may be charged all at once.

The treatment with the montmorillonite mineral is usually carried out at room temperature, and if heated, GMA is likely to polymerize, which is not preferable.

The montmorillonite mineral is usually separated from the treated crude GMA by an operation such as filtration or centrifugation.

Crude GMA separated from montmorillonite minerals
In the case of carrying out the distillation of 1, the temperature during the distillation is preferably low from the viewpoint of preventing polymerization, but it must be determined in consideration of the capacity of the pressure reducer and the capacity of the condenser. Despite the small capacity of the condenser, if the degree of pressure reduction is increased and the distillation temperature is lowered, low boiling point compounds (eg MMA) cannot be collected and recovery loss increases. Therefore, usually 1-3
It is preferable to carry out the distillation at a pressure of 0 Torr.

Although not particularly limited to the type of distillation column,
If possible, a low pressure loss distillation column is preferred. Furthermore, it is preferable that the actual number of distillation columns is as small as possible. A distillation column with a low pressure loss or a distillation column with a small number of actual stages can keep the bottom pressure low, that is, the bottom temperature can be kept low.
This is because polymerization is unlikely to occur.

The distillation method may be a batch method or a continuous method.

Specifically, when the batch method is used, crude GMA treated with a montmorillonite mineral is put in a kettle together with a polymerization inhibitor, and the polymerization inhibitor is continuously added to the tower top and the condenser. Distill under reduced pressure. In order to prevent polymerization, the kettle may be charged with air or dilution air for distillation.

When performing continuous distillation, crude GMA treated with a montmorillonite mineral is continuously charged into a distillation column together with a polymerization inhibitor, and unreacted GMA such as unreacted MMA is charged from the top of the column.
Components having a lower boiling point than MA are withdrawn, and GMA and components having a higher boiling point than GMA are withdrawn from the bottom of the column. The liquid discharged from the bottom of the column is further charged into the next continuous distillation column, the product GMA is obtained from the top of the column, and the component having a higher boiling point than that of GMA is discharged from the bottom of the column. Also in this case, the distillation is usually performed under reduced pressure while continuously adding the polymerization inhibitor to the top of the column and the condenser, and air or diluted air is charged in the kettle to prevent the polymerization and the distillation is performed.

The capacity of the reboiler in the case where the continuous distillation is carried out using a thermosiphon type reboiler is preferably as small as possible, although it depends on the amount of raw material charged and the capacity of the distillation column. Therefore, an evaporator such as a thin film evaporator having a shorter residence time than the thermosiphon type reboiler may be used as the reboiler.

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[Example 1] Production of crude GMA was carried out using a reaction distillation column consisting of a 10-stage 80 mmφ Oldershaw distillation column, a condenser, a decanter, a reflux line, a decompression device and a 20 Lsus 316 jacketed kettle. went. MMA 15600 g, triethylamine 65 g, n-hexane 2250 g, 2,6-di-ter in a 20 L kettle.
20 g of t-butyl-4-methylphenol and 20 g of methoxyphenol were charged, the bottom temperature was raised to 53 ° C. under reduced pressure of 200 Torr, and 1262 g of GD was added over 1 hour, and the mixture was kept at the same pressure and the same temperature for 4 hours. did.
After that, the lower layer liquid was extracted while returning the upper layer liquid separated by the decanter to the tower, and 1100 g of GD was charged.
After reacting until the bottom GD becomes 0.2 wt% or less, n-hexane removal, triethylamine removal and MMA removal
Finally, the crude GMA (MMA 1.1 wt%, GM
4621 g of A78.6 wt%, GD 0.4 wt% and other unknown high boiling point substances and low boiling point substances) were obtained. At this time, the GMA yield in the crude GMA was 80.7%, the GMA selectivity of the GD base was 81.7%, and the titration analysis with N / 100 hydrochloric acid was carried out by potentiometric titration to find that it was 6.5 mmol.
It was found that there was / kg of basic component.

[Example 2] 500 g of crude GMA of Example 1
And 25 g of KSF / O of K series catalyst manufactured by Nissan Gadler Co., Ltd. were stirred at room temperature for about 1 hour, the catalyst was separated by filtration, and the basic component in the filtrate was measured. No sex component was detected. Moreover, as a result of gas chromatographic analysis of this liquid, polymerization of GMA by this treatment was not observed at all.

Example 3] 500 g of crude GMA of Example 1 and 25 g of K series catalyst K series manufactured by Nissan Gadler Co., Ltd.
After stirring P10 at room temperature for about 1 hour, the catalyst was separated by filtration, and the basic component in the filtrate was measured.
It was found that there was / kg of basic component. Then, 5 g of KP10 was added to this filtrate again, and after stirring at room temperature for about 1 hour, the catalyst was separated by filtration and the basic component in the filtrate was measured, but no basic component was detected at all.
Moreover, as a result of gas chromatographic analysis of this liquid, polymerization of GMA by this treatment was not observed at all.

Example 4 A 100 ml glass flask as shown in FIG. 1, a single tube filled with a helipack (filler) (40 mmφ × 300 mm, helipack 30 mm filled)
The degree of growth of the seeds of the popcorn polymer placed on the SUS basket was evaluated using an apparatus equipped with a condenser.

The crude GMA treated with the montmorillonite mineral of Example 2 was treated with N-nitroso-N- as a polymerization inhibitor.
Cyclohexylaniline 5000 ppm, methoxyphenol 1000 ppm, and hydroquinone 1 ppm (in addition to the above inhibitors, 2,6-
Di-tert-butyl-4-methylphenol 4500
(containing ppm) was added to measure the seed growth rate of the popcorn polymer. Crude GMA with inhibitor added
60 g was placed in a flask, the degree of vacuum was controlled so that the temperature at the top of the column was 100 ° C., and the system was operated under a total reflux condition for 6 hours. As a result, the popco placed on the SUS basket
No increase in weight was observed for the seeds of the polymerized polymer (the seeds of the polymerized popcorn were thoroughly washed with n-hexane after completion of the total reflux, dried under reduced pressure, and weighed). No polymer deposit was found on the flask, condenser and empty column.

[Comparative Example 1] Evaluation was performed using the same evaluation apparatus as in Example 4.

In addition to the crude GMA of Example 1, as a polymerization inhibitor for the crude GMA, 5000 ppm of N-nitroso-N-cyclohexylaniline, 1000 ppm of methoxyphenol and 1 ppm of hydroquinone (in addition to the above inhibitors, GMA
2,6-di-tert-butyl-used in the production reaction
(Containing 4500 ppm of 4-methylphenol)
Was added to measure the seed growth rate of the popcorn polymer. 60 g of crude GMA added with an inhibitor was put in a flask, the degree of pressure reduction was controlled so that the temperature at the top of the tower was 100 ° C., and operation was carried out under a total reflux condition for 6 hours.
The experiment was stopped because a polymer was formed in the bottom during the temperature rise. Also, the seeds of the popcorn polymer placed on the SUS basket overflowed from the basket.

Comparative Example 1 shows that if the crude GMA is not treated with a montmorillonite-based mineral before the total reflux, the popcorn seeds grow remarkably and the liquid is very easily polymerized. [Embodiment 5] A reflux head and a top condenser are provided,
Sumitomo / Sulzer Lab Packing (45mm)
Batch distillation was performed using a vacuum jacket type distillation column in which 7 elements of φ × 55 mm) were filled. Distillation was performed using a 0.5 L glass flask equipped with a dilution air charging line, a bottom pressure measuring line and a bottom temperature measuring line as a batch kettle. 420 g of crude GMA of Example 2
As a polymerization inhibitor, N-nitroso-N-cyclohexylaniline 5000 ppm, methoxyphenol 100
0 ppm and hydroquinone 1 ppm (in addition to the above inhibitors, 2,6-di-tert used in the GMA production reaction)
-Butyl-4-methylphenol 4500 ppm) was added and batch distillation was carried out. During distillation,
On the top side of the column, 10 parts of GMA solution containing 10 ppm of hydroquinone was used.
It was continuously charged at a flow rate of ml / hr, and a GMA solution of methoxyphenol 500 ppm was added to the condenser side at 10 ml / h.
While continuously charging with r, distillation was carried out at a column top pressure of 20 Torr. It took about 9 hours to complete the distillation, but no polymer was found in any part of the distillation system. The distillation yield was 80.2% and the GMA purity of the obtained product was 9
It was 9.2%.

Comparative Example 2 Using the batch distillation apparatus of Example 5, 420 g of crude GMA of Example 1 was not treated with a montmorillonite mineral, but 5000 ppm of N-nitroso-N-cyclohexylaniline and methoxyphenol 1 were used.
000 ppm and hydroquinone 1 ppm (in addition to the above inhibitors, 2,6-di-te used in the GMA production reaction)
rt-Butyl-4-methylphenol) (containing 4500 ppm) was added and batch distillation was performed. During distillation, the column top side was continuously charged with 10 ppm hydroquinone GMA solution at 10 ml / hr, and the condenser side was charged 10 ml with 500 ppm methoxyphenol GMA solution.
Distillation was carried out at a column top pressure of 20 Torr while continuously charging at / hr.

At the first hour after the start of distillation, a popcorn polymer was formed in the gas phase of the bottom glass flask, so the distillation was stopped.

Comparative Example 2 shows that the crude GMA must be treated with a montmorillonite mineral before distillation to remove the basic component, and a polymerized product cannot be distilled.

[0034]

EFFECT OF THE INVENTION After producing glycidyl methacrylate by transesterification of glycidol and methyl methacrylate in the presence of a basic catalyst, treatment with a montmorillonite mineral prior to purification produces a polymer during purification. Is significantly suppressed, and glycidyl methacrylate can be obtained in high yield. (Below margin)

Claims (3)

[Claims] 1. A method for purifying glycidyl methacrylate produced by transesterification of glycidol and methyl methacrylate in the presence of a basic catalyst, which comprises treating with a montmorillonite-based mineral before purification. A characteristic method for purifying glycidyl methacrylate. 2. The method for purifying glycidyl methacrylate according to claim 1, wherein the basic catalyst is a tertiary amine. 3. The method for purifying glycidyl methacrylate according to claim 1 or 2, wherein the tertiary amine is triethylamine.