JPH04149175A - Purification of epoxidated (meth)acrylate - Google Patents

Abstract

PURPOSE:To enable purification of epoxidated (meth)acrylate by epoxidating cyclohexenylmethyl (meth)acrylate with an oxidizing agent, lowering the heating temperature and evaporating the solvent at low temperature by two stages. CONSTITUTION:A compound expressed by formula I (R is H or methyl) is subjected to epoxidation reaction using an oxidizing agent (e.g. peracetic acid) in a solvent such as ethyl acetate under a molecular oxygen-containing gas atmosphere at 0-70 deg.C. The solvent is evaporated from the reaction system using a thin film evaporator at a low evaporation temperature of <=100 deg.C to afford a crude liquid having 10-30wt.% solvent concentration. Then the crude liquid is further subjected to the second evaporation at a low evaporation temperature of <=100 deg.C. Thereby, the crude liquid is purified into a liquid having <1wt.% solvent content to provide the compound expressed by formula II. The resultant cyclohexylmethyl (meth)acrylate) is readily polymerizable and useful as ink, coating, adhesive, coating agent, a raw material for molding resin, modifier, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for purifying epoxidized cyclohexylmethyl (meth)acrylate.

More specifically, a method for purifying cyclohexylmethyl (meth)acrylate that makes it possible to reduce low-boiling substances in the product and further suppress the formation of polymeric products by performing the low-boiling removal step in two stages. It is related to. This cyclohexynylmethyl (meth)acrylate compound is heated,
It can be easily homopolymerized or copolymerized with other unsaturated group compounds in the presence of ultraviolet rays, ionizing radiation, or radical polymerization initiators, and is especially useful for introducing cationically cured alicyclic epoxy groups into polymers. It is valid. It is also useful as an intermediate raw material for paint resins. (Prior Art) Various acrylic acid ester monomers have been known. For example, monofunctional monomers such as methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate, and polyfunctional monomers such as trimethylolpropane triacrylate and pentaerythritol triacrylate are generally known. However, when monofunctional monomers are used in printing inks and paints, the odor of unreacted monomers after curing poses a serious problem.

Furthermore, when polyfunctional monomers are used as diluents for paints and printing inks, they have to be used in large amounts relative to the resin, which has the disadvantage that the properties of the resin are lost.

In this regard, the compound obtained by epoxidizing the cyclohexenylmethyl (meth)acrylate compound represented by [wherein R represents a hydrogen atom or a methyl group] with an oxidizing agent [wherein R represents a hydrogen atom or a methyl group] is It has low viscosity, low odor, and solubility in a wide range of resins, and is useful as a raw material or modifier for inks, paints, adhesives, coatings, and molding resins.

However, the epoxidized (meth)acrylic acid ester shown in this ritual (II) (hereinafter abbreviated as AETHB when R is a hydrogen atom, and METHB when R is a methyl group)
It is known that it is extremely susceptible to polymerization and is often polymerized by heat, light and other factors during the manufacturing process, storage and transportation.

In order to prevent these problems, Japanese Patent Application No. 1-320956 describes a method for preventing polymerization.

(Problems to be Solved by the Invention) In response to this, the present inventors have
It was confirmed that the polymerization preventing effect of the polymerization inhibitor described in Specification No. 56 (filed on December 11, 1999) was not yet sufficient.

One of the reasons for this is that at the time when Japanese Patent Application No. 1-320956 was filed, AETHB (METHB) had not yet been produced on an industrial scale, so the quality that the product should have was not sufficiently predicted.

In other words, the low-boiling components contained in AETHB (METHB) products must be reduced from 2 to 3% to 1%, and to achieve this, the heating temperature must be increased in the low-boiling removal process or the residence time must be lengthened. However, in such cases, the product contains trace amounts of polymers.

Developments in this regard have progressed since then, and it has become clear that there is a problem if the product contains trace amounts of polymers.

For example, when AETHB (METHB) containing a polymer is used to synthesize an intermediate raw material for paint resin, the polymer precipitates as a sticky insoluble substance, causing various problems in the process and causing damage to the paint. This will significantly reduce the product value of the product.

The trace amounts of polymers contained in the product AETHB (METHB) are thought to be mainly composed of low molecular weight polymers of AETHB (METHB) itself.

The content of these polymers is expressed as the weight percent of the polymers contained in the product by filtering the slurry produced when 10 g of the product is dissolved in 100 cc of n-hexane or n-hebutane and measuring the weight. (Such a solubility test using n-heptane is hereinafter referred to as Heptane Test-HT).

It is known that AETHB (METHB) that can be used as a product must have an HT of 0°1% or less.

On the other hand, the polymer content of AETHB (METHB) obtained by repeating the method described in Japanese Patent Application No. 1-320956 was found to be 0.14% in HT, which is sufficient in terms of quality. It is determined that there is no.

In other words, in order to industrially produce AETHB (METHB), it is necessary to establish a more effective method for inhibiting polymerization, and at the time the present inventors filed the application, there was still no technology that would enable this. It was.

The inventors of the present invention conducted intensive research to address these issues and found that lowering the heating temperature and removing the low boiling point of the solvent in two stages would extremely meet the above objectives, and finally satisfied the quality. The resulting AETHB (M, ETHB) was produced on an industrial scale, and a quality maintenance method was established in line with actual circumstances, leading to the completion of the present invention.

(Structure of the Invention) In other words, the present invention provides the following method: ``A cyclohexenyl methyl (meth)acrylate compound represented by the general formula (1) [wherein R represents a hydrogen atom or a methyl group] is epoxidized with an oxidizing agent to obtain a compound of the general formula (11) When producing a compound represented by the formula [wherein R represents a hydrogen atom or a methyl group], the crude reaction solution containing a solvent is first deoxidized at (a) heating temperature] at 0°C or lower. Boiling to obtain a crude liquid with a solvent content of 10 to 30% by weight, and then (b) delow boiling the crude liquid obtained in (a) at a heating temperature of 100'C or less. A method for purifying epoxidized cyclohexynolmethyl (meth)acrylate, which comprises the step of obtaining unpurified epoxidized cyclohexynylmethyl (meth)acrylate having a solvent content of 1% by weight.

The method for purifying AETHB (METHB) of the present invention will be explained in detail below.

First, the epochination reaction step will be explained.

That is, the (meth)acrylate compound represented by general formula (1) is epoxidized using an oxidizing agent.

The oxidizing agent used for this removal may be any oxidizing agent that can epoxidize unsaturated bonds, such as performic acid, peracetic acid, perpropionic acid,
Various hydroperoxides such as m-chloroperbenzoic acid, trifluoroperacetic acid, perbenzoic acid, tert-butyl hydroperoxide, cumyl hydroperoxide, tetralyl hydroperoxide, diisopropylbenzene hydroperoxide, and peroxide. Examples include hydrogen.

The oxidizing agent may also be used as a catalyst; for example, in the case of an organic peracid, an alkali such as sodium carbonate or an acid such as sulfuric acid may be used as the catalyst.

Similarly, when using the above-mentioned various hydroperoxides, a compound having a known catalytic ability such as molybdenum hexacarbonyl can be used, and when hydrogen peroxide is used, a mixture of tungstic acid and caustic soda can be used in combination.

When carrying out the reaction in batches, first, a predetermined amount of cyclohexenyl methyl (meth)acrylate is charged into the reaction vessel.
A catalyst and a stabilizer are dissolved in this as required, and the oxidizing agent is dropped into the solution.

The reaction molar ratio between the oxidizing agent and cyclohexenyl methyl (meth)acrylate is theoretically 1/1, but in the method of the present invention it is in the range of 0.1 to 10, preferably 0.5 to 10
, more preferably from 0.8 to 1.5.

If the molar ratio between the oxidizing agent and cyclohexenylmethyl (meth)acrylate exceeds 10, the conversion rate and reaction time of cyclohexenylmethyl (meth)acrylate will be reduced;
Although it is preferable in terms of reducing loss due to polymerization of (meth)acrylate, it has disadvantages such as side reactions caused by excess oxidizing agent, oxidizing agent selectivity, and large costs required when recovering unreacted oxidizing agent. be.

On the other hand, when the molar ratio of the oxidizing agent and cyclohexenyl methyl (meth)acrylate is less than 0.01, the conversion rate and selectivity of the oxidizing agent are high, which is preferable in terms of preventing side reactions of the product caused by the oxidizing agent. There are disadvantages such as loss due to polymerization of meth)acrylate and a large amount of cost required to recover unreacted cyclohexenylmethyl (meth)acrylate.

The reaction temperature is carried out below the upper limit so that the epoxidation reaction takes precedence over the decomposition reaction of the oxidizing agent. For example, when using peracetic acid, it is 70°C or less, and when using tanyabutyl hydroperoxide, it is 150°C or less. preferable.

If the reaction temperature is low, it will take a long time to complete the reaction, so it is preferable to carry out the reaction at a temperature higher than the lower limit of 0° C. when peracetic acid is used and 20° C. when tert-butyl hydroperoxide is used.

In addition, during epoxidation, a side reaction occurs in which the epoxy group opens the ring with an organic acid, alcohol, or water due to by-products from the oxidizing agent. Select and implement from the temperature range.

The reaction pressure is generally operated at normal pressure, but it can also be carried out under elevated or low pressure.

Although the reaction can be carried out in the absence of a solvent, it is preferable to carry out the reaction in the presence of a solvent, since this has the effect of reducing the viscosity of the reaction crude liquid and stabilizing it by diluting the oxidizing agent).

Examples of solvents used include aromatic compounds such as Hensen, toluene, and xylene, halides such as chloroform, dimethyl chloride, carbon tetrachloride, and chlorobenzene, ester compounds such as ethyl acetate and butylene acetate, acetone, methyl ethyl ketone, etc. Ketone compounds, ether compounds such as 1,2-dimethquinethane, etc. can be used.

The amount of solvent to be used is preferably 0.5 to 5 times the amount of cyclohexenylmethyl (meth)acrylate.

If the amount is less than 0.5 times, there will be little stabilizing effect by diluting the oxidizing agent, and conversely, if it is more than 5 times the amount, the stabilizing effect will not be as great, and it will not swell and will greatly reduce the recovery of the solvent. It costs a lot of money, so it's a waste.

Further, when performing the above-mentioned epoxidation reaction, a polymerization inhibitor described in Japanese Patent Application No. 1-320956 must be used together with a molecular oxygen-containing gas.

Air is usually used as molecular oxygen and is blown into the reactor.

The blowing position may be either directly into the liquid or into the gas phase.

The amount of blowing can be arbitrarily selected, but too much is not preferable because it will result in solvent loss.

The reaction is carried out continuously or batchwise, and in the case of continuous reaction, a piston flow type is preferred.

The end point of the reaction can be confirmed by the concentration of the remaining oxidizing agent or by gas chromatography.

The epoxidation product reaction crude liquid obtained in the reaction can be purified by distillation of low-boiling components such as solvents, low-boiling substances, unreacted raw materials, and catalysts, neutralization, and treatment with adsorbents and ion exchange resins. .

Particularly when an organic peracid is used as the oxidizing agent, it is preferable to neutralize and wash the reaction crude solution with water.

This is because if a low boiling point component such as a solvent is removed without neutralization, polymerization is extremely likely to occur.

Examples of alkaline aqueous solutions used for neutralization include Na0H
SKOHSK2CO3, Na= co, , NaHCO,
, KHCO, NH, etc. can be used, the concentrations thereof being freely selectable within wide limits.

From the viewpoint of liquid separation or loss, NaOH aqueous solution, Na2c
o! Preferably, an aqueous solution is used.

The neutralization and water washing steps are carried out at 10-90°C, preferably at 10°C.
It is preferable to carry out at a temperature range of ~50°C.

In order to remove low boiling point components from the reaction crude liquid that has been neutralized or washed with water, it is preferable to use a thin film evaporator or the like after adding a polymerization inhibitor.

In particular, the polymerization inhibitor contained in the reaction crude liquid may be extracted into the lower layer and the content in the neutralized upper layer liquid may be reduced. Preferably, appropriate amounts of the polymerization inhibitors mentioned are supplemented.

It is also preferable to blow molecular oxygen into the system during neutralization washing.

In the neutralization water washing step, it is important to neutralize and remove the organic acid as well as remove the residual organic peracid.

In order to operate the next low boiling point component removal step stably, the residual organic peracid content in the neutralized upper layer liquid must be reduced to 0. It is necessary to repeat neutralization and water washing until the concentration is 1% or less, preferably 0.01% or less.

The amount of alkali used for neutralization washing with water is 0.5 to 3 times the equivalent amount of organic acid in the crude reaction solution, preferably 0.8
It is best to use ~1.8 times the amount; it is not economical to increase the amount more than necessary.

Further, if the equivalent ratio is lowered more than necessary, it is not a good idea because a large amount of water is required to remove the organic acid, and the loss of solvents and the like to the lower water layer also increases. Following the neutralization water wash step, the solvent is removed.

Next, AETHB (METHB
) The purification method in which the low boiling point removing step is carried out in two stages will be explained in detail.

The neutralized upper layer solution obtained above was AETHB (METHB
), a system containing unreacted substances, solvents, and low-boiling components.

This neutralized upper layer solution contains 1 of AETHB (METHB).
．． Contains more than 7 times the amount of solvent by weight.

For example, a neutralized reaction crude solution obtained by adding 3.7 times the weight of cyclohexenylmethyl (meth)acrylate solvent contains 80% by weight of the solvent.

The solvent can be removed from this neutralized supernatant liquid using a thin film evaporator using known techniques.

The desolvation treatment of the neutralized upper layer liquid is often a one-stage treatment step for boat fishing to simplify the process.

In addition, a thin film evaporator is usually used for removing the solvent, but the heating temperature is 50 to 180°C, preferably 50°C to prevent polymerization.
It is said that it is best to carry out the process at a temperature of ~100°C.

Further, although the pressure can be arbitrarily selected depending on the physical properties of the solvent, it is generally said that the operation is performed under reduced pressure in relation to the heating temperature.

However, since the solvent is removed to 1% by weight or less in one stage,
When a high vacuum is used, the volume of solvent vapor becomes enormous, and a large evaporator is required to achieve sufficient evaporation capacity.

On the other hand, if it is carried out in a low vacuum, the heating temperature must be increased, which accelerates polymerization.

Furthermore, even if the heating temperature is lowered, the A
The residence time of ETHB (METHB) becomes longer and polymerization is promoted.

In other words, if 1% by weight of the solvent is removed in one stage, IT
Therefore, it is impossible to obtain a product with a quality of 0.1% or less.

Therefore, we are increasing the quality of products with HT of 0.1% or less.
We searched for conditions that would allow the amount of solvent in B (METHB) to be 1% by weight or less.

As a result, the heating temperature was lowered and the solvent in the crude liquid was
It was found that the objective could be achieved by performing evaporation removal in stages.

In other words, in the first stage desolvation step, the heating temperature is 50 to 100°C.
, preferably at a temperature in the range of 50 to 70°C.

Further, the pressure at that time can be arbitrarily selected depending on the physical properties of the solvent, but it is common to operate under reduced pressure depending on the heating temperature.

The solvent concentration in the bottom liquid of the thin film evaporator thus obtained is preferably in the range of 10 to 30% by weight.

If the solvent concentration is 10% by weight or less, a high vacuum must be applied, and when the distilled solvent is collected with a condenser, recovery loss becomes large, which is not preferable.

On the other hand, when the solvent concentration is 30% by weight or more, it is not preferable because the second stage desolvation step is carried out under high vacuum, so the distilled solvent cannot be repaired with a condenser and recovery losses increase.

The second stage desolvation step is preferably carried out at a heating temperature of 50 to 100°C, preferably 50 to 70°C. Further, the pressure at that time varies depending on the physical properties of the solvent, but can be arbitrarily selected in relation to the heating temperature.

As described in Japanese Patent Application No. 1-320956, molecular oxygen, which has a polymerization-preventing effect, can be introduced into the evaporator at any point, but it is usually introduced from the line where the bottom liquid is distilled. .

The amount of injection can be selected arbitrarily, but the upper limit is naturally limited by the capacity of the vacuum system, whether the bottom liquid flows down stably, or the recovery loss when collecting the distilled solvent with a condenser. .

The bottom liquid obtained in the solvent removal step has a purity of 95 to 97% by weight, but as a result of the present invention, the solvent concentration is 1% by weight.
Hereinafter, HT is 0. The quality is about less than 1% by weight.

(Effects of the Invention) The effects of the present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1500 gr of cyclohexenyl methyl acrylate and 045 gr of ethyl acetate were added to a 15N SUS reactor equipped with a stirrer and a cooling jacket, and oxygen/nitrogen (10/90 capacity%)
A mixed gas of 32 NII/Hr was blown into the reactor.

Next, the reaction temperature was kept at 40°C, and a 30% peracetic acid solution was added at 28°C.
12 gr was charged over 4 hours using a metering pump. After the preparation was completed, the reaction was further aged for 5 hours and then terminated.

After cooling the reaction crude liquid to room temperature] 5000 g of O% NaOH
was added and stirred for 30 minutes, then left to stand for 30 minutes to separate the liquids.

After removing the lower layer liquid, 10% NaNaOH5O00 was further added and the same operation was performed.

At this time, the residual peracetic acid concentration in the upper layer liquid was 0.02%, and acetic acid had completely disappeared.

Next, when 1% NaNaOH5O00 was added and the same operation was performed, the peracetic acid content was 0.01% or less.

Next, 0.45 gr of hydroquinone monomethyl ether was added to 6060 g of the neutralized upper layer liquid, and a first stage desolvation treatment was performed using an SUS thin film evaporator.

The operating conditions were a heating temperature of 60°C, a pressure of 150 mmHg, and a mixed gas of oxygen/nitrogen at 32 R from the bottom liquid distillation line.
/H r.

1630g of this column bottom liquid was heated at a temperature of 60℃ and a pressure of 40m.
Oxygen/nitrogen (10/9
A mixed gas of 0% by volume) was blown in at 32 Ng/Hr.

The amount of bottom liquid obtained was 1480 gr.

Further, the composition was investigated by gas chromatography analysis and found to be 896.2% AETH and 0 ethyl acetate.

1%, 0 cyclohexenyl methyl acrylate.

9%, others 2.8%.

As a result of HT, the polymer content was 0.01%.

Comparative example Contents 1, 51 with stirrer and cooling jacket
Add 1500g of cyclohexenyl methyl acrylate and 5045g of ethyl acetate to the SUS reactor in Step 1.
Oxygen/nitrogen (10/90% by volume) is added to the reactor from the tube inserted into the reactor.
) was blown in at a rate of 32 NN/Hr.

Next, the reaction temperature was kept at 40°C, and a 30% peracetic acid solution was added at 28°C.
12 gr was charged over 4 hours using a metering pump. After the preparation was completed, the reaction was further aged for 5 hours and then terminated.

After cooling the reaction crude liquid to room temperature, add 10% NaNaOH5O00
was added and stirred for 30 minutes, then left to stand for 30 minutes to separate the liquids.

After removing the lower layer liquid, add 10% Na. Oh 5 0
Add 00gr and perform the same operation.

At this time, the residual peracetic acid concentration in the upper layer liquid was 0.02%, and acetic acid had completely disappeared.

Next, 5000 g of 1% NaOH was added and the same operation was performed, and the peracetic acid content was 0.01% or less.

Next, 0□ 45 gr of hydroquinone monomethyl ether was added to 6126 gr, and the mixture was treated with a SUS Smith-type thin film evaporator solvent.

The operating conditions were a heating temperature of 100°C and a pressure of 1.50 m mH.
At 3 g, a mixed gas of oxygen/nitrogen is introduced from the bottom liquid distillation line at 3 g.
It was blown in at 2Ng/Hr.

The amount of bottom liquid obtained was 1348 gr.

Further, the composition was examined by gas chromatography analysis and found to be 894.5% of AETH, 18% of ethyl acetate, 1.0% of cyclohexenyl methyl acrylate, and 2.6% of others.

When HT was performed, the polymer content was 0. It was 25%.

Claims (1)

[Claims] General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (I) Cyclohexenylmethyl (meth) represented by [In the formula, R represents a hydrogen atom or a methyl group] Epoxidizes an acrylate compound with an oxidizing agent to produce a compound represented by the general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) [In the formula, R represents a hydrogen atom or a methyl group] When doing so, the crude reaction solution containing the solvent is first (a) de-low boiled at a heating temperature of 100°C or less,
A process of obtaining a crude liquid with a solvent content of 10 to 30% by weight is carried out, and then (b) the crude liquid obtained in (a) is deboiled at a heating temperature of 100°C or less to reduce the solvent content to 1% by weight. A method for purifying epoxidized cyclohexylmethyl (meth)acrylate, characterized in that it consists of a step of obtaining epoxidized cyclohexylmethyl (meth)acrylate of less than