JP3250200B2 - Purification method of glycidyl methacrylate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to glycidol (hereinafter referred to as "glycidol").
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).

[0002] GMA has a highly reactive double bond and an epoxy group in the molecule, and is used as a resin material for coatings.

[0003]

2. Description of the Related Art Many processes for producing GMA by transesterification between GD and MMA have been known so far. In general, methanol produced as a by-product is distilled off in the presence of a basic catalyst by distillation. Perform the reaction while removing to the outside.

After completion of the reaction, the catalyst used in the reaction is GM
Filtration prior to purification of A (JP-B 53-6133 / Degussa,
JP-B-61-43351 / Nippon Oil & Fats)
No. 5,105,676 / Mitsui east pressure). It is very difficult to completely remove the catalyst before the purification of the crude GMA by the above-mentioned filtration and washing with water. ing. Further, in water washing, there are problems such as an increase in loss of GMA and recovered MMA. When amines are used as a catalyst for the reaction (JP-A-55-94379 / Daicel Chemical Industries), the amines are removed from GMA. Since it has a low boiling point, it can be removed outside the system by distillation prior to GMA. However, a very small part of the amine undergoes a side reaction and remains as a high-boiling compound on the kettle side during GMA purification.
There is a problem that polymerization is likely to occur during crude GMA purification.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing GMA by transesterification of GD with MMA, which prevents the polymerization of crude GMA which is very liable to polymerize during distillation purification, and provides a high yield and high purity. The aim is to develop a method for obtaining the product GMA.

[0006]

That is, the present invention provides:
"A method for purifying glycidyl methacrylate produced by a transesterification reaction of glycidol and methyl methacrylate in the presence of a basic catalyst, wherein methacrylic acid is purified after treatment with a montmorillonite mineral before purification. Purification Method of Glycidyl Acid ”.

The basic catalyst referred to in the present invention includes carboxylic acid salts of alkali metals and alkaline earth metals such as lithium acetate, potassium acetate and magnesium acetate, and triethylamine, tributylamine, dibutylamine and the like which are usually used as basic catalysts. However, other basic catalysts can be used in the practice of the present invention. The production of GMA by the transesterification reaction between GD and MMA of the present invention can be carried out by ordinary reactive distillation in which methanol produced by the reaction is removed from the top of the column. It should be noted that even if a solvent such as n-hexane or cyclohexane is used as an azeotropic agent for methanol, there is no problem in practicing the present invention.

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

[0009] Usually, the problem is that the crude GMA (which naturally contains MMA) after de-MMA is converted to product GM.
This is to prevent polymerization in the step of separating A by distillation.

As a result of a detailed study by the present inventors, it has been found that, after treatment with a montmorillonite-based mineral, removal by filtration or centrifugation outside the system allows the basic catalyst to be adsorbed and removed, making it extremely difficult to polymerize during purification by distillation. It turned out to be.

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

The montmorillonite mineral used for the treatment of the crude GMA must be determined according to the amount of the residual base in the crude GMA, but it is usually preferable to use 0.1 to 10% by weight based on the crude GMA. Excessive use of the montmorillonite mineral is not preferred because not only is the separation from the treated crude GMA complicated, but also the usage rate increases.

[0013] The montmorillonite mineral may be added as it is by stirring the untreated crude GMA with a stirrer while removing heat. In addition, the montmorillonite mineral may be charged by dividing into several times, or may be charged all at once.

The treatment with the montmorillonite mineral is usually carried out at normal temperature, and when heated, GMA is more likely to be polymerized, 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 mineral
When performing distillation, the temperature during distillation is preferably low from the viewpoint of preventing polymerization, but it is necessary to determine the temperature in consideration of the capacity of the pressure reducer and the capacity of the condenser. Despite the low capacity of the condenser, if the degree of vacuum is increased and the distillation temperature is lowered, low boiling compounds (for example, MMA) cannot be collected completely, and the recovery loss increases. Therefore, usually 1-3
Preferably, the distillation is performed at a pressure of 0 Torr.

The type of the distillation column is not particularly limited.
Preferably, a distillation column having a low pressure loss is used. Further, it is preferable that the actual number of distillation columns is as small as possible. Since the distillation column with low pressure loss and the distillation column with a small number of actual plates can keep the bottom pressure low, that is, the bottom temperature can be kept low,
This is because polymerization hardly occurs.

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-based mineral is put into a kettle together with a polymerization inhibitor, and the polymerization inhibitor is continuously added to the top and the condenser. Distill under reduced pressure. In order to prevent polymerization, distillation may be performed by charging air or dilution air into the kettle.

In the case of performing continuous distillation, crude GMA treated with a montmorillonite mineral is continuously charged into a distillation column together with a polymerization inhibitor, and GMA such as unreacted MMA is charged from the top of the column.
A component having a lower boiling point than MA is withdrawn, and GMA and a component with 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, and a product GMA is obtained from the top of the column, and a component having a higher boiling point than GMA is discharged from the bottom of the column. Also in this case, distillation is performed under reduced pressure while continuously adding a polymerization inhibitor to the top of the column and the condenser, and distillation is performed by charging air or dilution air in the kettle to prevent polymerization.

When continuous distillation is carried out using a thermosiphon reboiler, the reboiler capacity is preferably as small as possible, although it depends on the amount of raw materials charged and the capacity of the distillation column. Therefore, an evaporator such as a thin film evaporator having a shorter residence time than a thermosiphon 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 The production of crude GMA was carried out using a 10-stage, 80 mmφ, old distillation column, a condenser, a decanter, a reflux line, a decompression device, and a 20 Lsus 316 jacketed kettle with a jacket. went. In a 20 L kettle, 15600 g of MMA, 65 g of triethylamine, 2250 g of n-hexane, 2,6-di-ter
20 g of t-butyl-4-methylphenol and 20 g of methoxyphenol were added, and the temperature was raised to a bottom temperature of 53 ° C. under reduced pressure of 200 Torr. Then, 1262 g of GD was charged over 1 hour, and kept at the same pressure and the same temperature for 4 hours. did.
Thereafter, the lower layer liquid was withdrawn while returning the upper layer liquid separated by a decanter to the tower, and further charged with 1100 g of GD.
After reacting until the GD of the bottom becomes 0.2 wt% or less, n-hexane, triethylamine and MMA are removed.
And finally GMA (MMA 1.1 wt%, GM
(A78.6 wt%, GD 0.4 wt%, and other unknown high-boiling substances and low-boiling substances) 4621 g. At this time, the yield of GMA in the crude GMA was 80.7%, and the selectivity of GMA based on GD was 81.7%. Titration analysis with N / 100 hydrochloric acid by potentiometric titration revealed that 6.5 mmol was obtained.
/ Kg of basic component was found to be present.

Example 2 500 g of crude GMA of Example 1
After stirring KSF / O of 25 g of K series catalyst manufactured by Nissan Gardler Co., Ltd. for about 1 hour at room temperature, the catalyst was separated by filtration and the basic component in the filtrate was measured. No sexual components were detected. Further, as a result of performing gas chromatographic analysis of this liquid, polymerization of GMA by this treatment was not recognized at all.

Example 3] 500 g of the crude GMA of Example 1 and 25 g of K of a K series catalyst manufactured by Nissan Gardora 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.
/ Kg of basic component was found to be present. Then, 5 g of KP10 was again added to the filtrate, and the mixture was stirred at room temperature for about 1 hour. After filtering off the catalyst and measuring the basic component in the filtrate, no basic component was detected.
Further, as a result of performing gas chromatographic analysis of this liquid, polymerization of GMA by this treatment was not recognized at all.

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

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

Comparative Example 1 Evaluation was performed using the same evaluation device as in Example 4.

The crude GMA of Example 1 was used as a polymerization inhibitor for N-nitroso-N-cyclohexylaniline 5000 ppm, methoxyphenol 1000 ppm and hydroquinone 1 ppm (in addition to the above inhibitors, GMA
2,6-di-tert-butyl- used during the production reaction
Contains 4500 ppm of 4-methylphenol)
Was added to measure the growth rate of the popcorn polymer seeds. 60 g of crude GMA to which the inhibitor was added was charged into the flask, the degree of vacuum was controlled so that the temperature at the top of the column was 100 ° C., and operation was carried out at full reflux for 6 hours.
The experiment was stopped due to the formation of polymer on the bottom during the heating. 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 mineral before the total reflux, the popcorn seeds grow remarkably and are very easily polymerized. Example 5 A reflux head and a top condenser were provided.
Sumitomo / Sulza-Labo Packing (45mm
Batch distillation was performed using a vacuum jacketed distillation tower packed with 7 elements (φ × 55 mm). Distillation was performed using a 0.5 L glass flask equipped with a dilution air charging line, a bottom pressure measurement line, and a bottom temperature measurement 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) was added and batch distillation was carried out. During distillation,
A 10 ppm GMA solution of hydroquinone was added to the top of the column.
ml / hr, and a 500 ppm GMA solution of methoxyphenol was added to the condenser side at 10 ml / hr.
The distillation was carried out at a top pressure of 20 Torr while continuously charging with r. 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
9.2%.

Comparative Example 2 Using the batch distillation apparatus of Example 5, 420 g of the crude GMA of Example 1 was not treated with a montmorillonite-based mineral, and N-nitroso-N-cyclohexylaniline 5000 ppm 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 (4500 ppm) was added and batch distillation was carried out. During the distillation, a GMA solution containing 10 ppm of hydroquinone was continuously charged at the top of the column at a rate of 10 ml / hr, and a GMA solution containing 500 ppm of methoxyphenol was added to the condenser at a rate of 10 ml.
The distillation was performed at a top pressure of 20 Torr while continuously charging at / hr.

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

Comparative Example 2 shows that unless the crude GMA is treated with a montmorillonite mineral before distillation to remove the basic component, a polymer is formed and distillation cannot be performed.

[0034]

According to the present invention, glycidyl methacrylate is produced by transesterification between glycidol and methyl methacrylate in the presence of a basic catalyst, and then treated with a montmorillonite-based mineral before purification to produce a polymer during purification. Glycidyl methacrylate can be obtained in high yield. (Below)

Claims (3)

(57) [Claims] 1. A method for purifying glycidyl methacrylate produced by a transesterification reaction of glycidol and methyl methacrylate in the presence of a basic catalyst, the method comprising purifying the glycidyl methacrylate with a montmorillonite mineral before purification. 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, wherein the tertiary amine is triethylamine.