JPH0931018A - Production of pentaerythritol (meth)acrylates - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply obtain the subject compound useful as a raw material for coatings, etc., in a high purity and in a high yield in a state capable of easily adjusting the ratio of partial ester compounds by subjecting pentaerythritol and a (meth)acrylate to a transesterification reaction in the presence of a catalyst in a specific solvent. SOLUTION: A method for producing a pentaerythritol (meth)acrylate comprises subjecting (D) pentaerythritol and (E) a (meth)acrylate [e.g. the ester of (meth)acrylic acid with a 1-4C aliphatic alcohol] in the presence of (A) a catalyst such as lithium hydroxide and, if necessary, further (C) a polymerization inhibitor in (B) a pentaerythritol-soluble organic solvent [e.g. dimethylformaldehyde, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrothiophene-1,1-dioxide].

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing pentaerythritol (meth) acrylic esters by a transesterification reaction, and more specifically, pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol. The present invention relates to a method for producing a pentaerythritol (meth) acrylic ester which contains a large amount of a partial ester such as mono (meth) acrylic ester and is liquid at room temperature by transesterification.

[0002]

2. Description of the Related Art Pentaerythritol (meth) acrylic esters are used alone or mixed with other polymerizable monomers, oligomers, polymers, dyes, pigments, inorganic fillers, etc. to prepare peroxides, persulfates, azobis compounds, In the presence of radical initiators such as ketone compounds, they are easily polymerized by radicals generated by thermal decomposition of these initiators or decomposition by irradiation of ultraviolet rays or radiation, and mechanical properties, heat resistance, weather resistance, oxidation resistance, etc. It produces excellent polymer.

Further, since pentaerythritol (meth) acrylic esters are easily copolymerized with various compounds having a carbon-carbon double bond, it is possible to adjust the physical properties of the polymer depending on the application. It is used in a wide range of fields as a raw material for paints, inks, coating agents, adhesives, adhesives, resins, rubbers, optical materials and the like.

The above-mentioned pentaerythritol (meth) acrylic esters are usually pentaerythritol and (meth)
It is obtained by a dehydration esterification reaction with acrylic acid.
Pentaerythritol (meth) obtained by these reactions
Acrylic esters are usually pentaerythritol tetra (meth) acrylic ester, pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol mono (meth) acrylic ester and pentaerythritol and poly (meth) acrylic ester. It contains oligomers such as acid esters.

This pentaerythritol (meth) acrylic ester becomes solid at room temperature, is inconvenient to handle, and has a small number of residual hydroxyl groups, especially when the content of pentaerythritol tetra (meth) acrylic ester is large. It becomes difficult to carry out a reaction utilizing residual hydroxyl groups in (meth) acrylic esters such as the synthesis of urethane acrylates by the reaction with isocyanates.

Moreover, pentaerythritol and (meth)
In the dehydration esterification reaction with acrylic acid, pentaerythritol is insoluble in general organic solvents, and tri (meth) acrylic ester of pentaerythritol produced by the reaction of pentaerythritol slightly dissolved in (meth) acrylic acid is used. When dissolved in a solvent, pentaerythritol tetra (meth) acrylic ester is preferentially produced, so that the amount of solid pentaerythritol tetra (meth) acrylic ester produced at room temperature is increased, and the resulting pentaerythritol (meth) acrylic ester is produced. The species go into a solid state at room temperature.

To solve this, Japanese Patent Laid-Open No. 1-199
Japanese Patent No. 936 discloses that partial production of pentaerythritol tetra (meth) acrylic ester is suppressed, and partial esters such as pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol mono (meth) acrylic ester, etc. Disclosed is a method for producing pentaerythritol (meth) acrylic esters which contain a large amount of body and can maintain a liquid state at room temperature. According to this production method, the esterification product water is allowed to be present in the reaction system in the dehydration esterification reaction in the first stage to increase the esterification rate of pentaerythritol to 20
To 70% by weight, and then the water produced in the second-stage dehydration esterification reaction is removed from the reaction system to adjust the esterification rate to 75-9.
It has been shown that the production of pentaerythritol tetra (meth) acrylic ester can be suppressed by stopping the reaction at 5% by weight.

Further, JP-A-56-32438, JP-A-2-157246 and the like disclose a polyhydric alcohol and a lower ester of (meth) acrylic acid in the presence of an organic solvent such as n-hexane and a catalyst. A method for producing a (meth) acrylic ester of a polyhydric alcohol by transesterifying and is disclosed.

[0009]

However, when the dehydration esterification reaction is carried out according to the method disclosed in JP-A-1-199936, although the amount of pentaerythritol tetra (meth) acrylic ester produced is small, As the amount of oligomers produced increases, pentaerythritol (meth), which is liquid at room temperature with high purity and yield
It was impossible to obtain acrylic esters.

When the transesterification reaction is carried out using pentaerythritol as the polyhydric alcohol according to the methods disclosed in the above-mentioned JP-A-56-32438 and JP-A-2-157246, pentaerythritol is used. Does not dissolve not only in an organic solvent such as n-hexane but also in a (meth) acrylic acid ester which is a reaction raw material, so that the reaction does not proceed.

The problem to be solved by the present invention is that a large amount of partial ester compounds such as pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol mono (meth) acrylic ester are produced, It is an object of the present invention to provide a method for producing pentaerythritol (meth) acrylic esters which are liquid at room temperature with high purity and high yield.

[0012]

As a result of intensive studies to solve the above problems, the present inventors have found that pentaerythritol and (meth) acrylic acid ester can be treated with a catalyst, a polymerization inhibitor and pentaerythritol. When the transesterification reaction is performed in the presence of a soluble organic solvent, a large amount of partial ester forms such as pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol mono (meth) acrylic ester are produced. The content of tetraester is low, and pentaerythritol (meth) acrylic esters that are liquid at room temperature can be easily obtained in high purity and high yield. Furthermore, the degree of transesterification depends on the amount of catalyst, reaction time, etc. The pentaerythritol (meth) acrylic ester obtained by adjusting the It found to be able to easily adjust the ratio of Raesuteru body and the partial esters thereof, and have completed the present invention.

That is, according to the present invention, pentaerythritol (meth) acrylate is subjected to transesterification reaction in the presence of a catalyst and an organic solvent in which pentaerythritol is soluble.
A method for producing an acrylic ester is provided.

The (meth) acrylic acid ester used in the present invention may be any ester which can undergo a transesterification reaction with pentaerythritol, but the alcohol produced by the transesterification reaction is distilled out of the system to promote the reaction. In order to do so, those which produce low boiling point alcohols such as methanol, ethanol, n-propyl alcohol, i
-Propyl alcohol, n-propyl alcohol, n-
Carbon number 1 such as butyl alcohol, i-butyl alcohol, s-butyl alcohol, t-butyl alcohol, etc.
An ester of an aliphatic alcohol of 4 to (meth) acrylic acid is preferable.

The amount of the (meth) acrylic acid ester used varies depending on the desired composition of the pentaerythritol (meth) acrylic ester, but is usually 2.0 to 10.0 mol, preferably 1 mol of pentaerythritol. Is selected from the range of 3.5 to 6.0 mol.

The catalyst used in the present invention may be any compound that functions as a catalyst in a normal transesterification reaction such as an acidic compound, a basic compound, an organometallic compound and the like, and examples thereof include sulfuric acid, hydrochloric acid, chlorosulfuric acid and phosphoric acid. Inorganic acids, metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide and calcium hydroxide, metal carbonates such as sodium carbonate, potassium carbonate, lithium carbonate and calcium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, etc. Metal bicarbonate, lauryl octyl tin, butyl tin oxide,
Examples thereof include organic metal compounds such as isopropoxy titanium and acetylacetone copper complex, and these may be used alone or in combination. Among these catalysts, basic inorganic lithium compounds, such as lithium hydroxide, lithium carbonate, and lithium hydrogen carbonate, are preferable because of their high transesterification catalytic function, low cost, and easy handling, and lithium hydroxide is particularly preferable. .

The amount of the above catalyst used is usually 0.001 to 1 part by weight, preferably 0.0 to 100 parts by weight of pentaerythritol and (meth) acrylic acid ester in total.
1 to 0.1 part by weight.

The organic solvent used in the present invention may be a compound in which pentaerythritol is soluble and does not affect the reaction, but among them, solubility of pentaerythritol, availability, stability during reaction, etc. A polar organic solvent containing a nitrogen atom or a sulfur atom, such as formamide, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrothiophene-1,1-dioxide, etc., is preferable because they are excellent.

The amount of the organic solvent used is usually 0.1 to 100 parts by weight per 1 part by weight of pentaerythritol,
It is preferably 1 to 10 parts by weight.

The reaction temperature of the transesterification reaction carried out in the present invention is usually 20 to 200 ° C., preferably 50 to 100 ° C., although it varies depending on the amount of (meth) acrylic acid ester used and the type of organic solvent. The reaction time varies depending on the amount of the (meth) acrylic acid ester used and the reaction temperature, but is usually 1 to 20 hours, preferably 3 to 8 hours.

In the transesterification reaction carried out in the present invention,
In order to prevent the polymerization of pentaerythritol (meth) acrylic esters and (meth) acrylic acid ester, it is preferable to use a polymerization inhibitor together. The polymerization inhibitor used here may be any compound effective in inhibiting the polymerization of pentaerythritol (meth) acrylic esters or (meth) acrylic acid esters, and examples thereof include hydroquinone, methylhydroquinone, tert-butylhydroquinone,
Phenolic compounds such as methquinone, 2,4-dimethyl-6-tert-butylphenol, catechol, tert-butylcatechol, amines such as phenothiazine, p-phenylenediamine, diphenylamine, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, dibutyl. Examples thereof include copper complex compounds such as copper dithiocarbamate and inorganic copper compounds such as copper sulfate, copper oxide and copper chloride. These may be used alone or in combination. Further, oxygen or a mixture of oxygen and an inert gas, such as air, may be used alone or in combination with the above-mentioned polymerization inhibitor to inhibit the polymerization.

The amount of the polymerization inhibitor used is usually 0.001 to 1 part by weight, preferably 0.01 to 0.1 part by weight, based on 100 parts by weight of pentaerythritol and (meth) acrylic acid ester in total. Is.

After completion of the reaction, the intended pentaerythritol (meth) acrylic ester can be obtained by using a known separation and removal method or the like. For example, after neutralizing the catalyst with an acid, the neutralized salt is removed by filtration, the unreacted (meth) acrylic acid ester is distilled off under reduced pressure, and if necessary, the pentaerythritol obtained is removed. It is also possible to increase the degree of purification by adding an organic solvent immiscible with water to the (meth) acrylic esters, washing with water, and concentrating. However, when washing is performed with water, water-soluble pentaerythritol di (meth) acrylic ester and mono (meth) acrylic ester are distilled out, so that purified pentaerythritol (meth) acrylic esters are pentaerythritol tetra ( A mixture of (meth) acrylic ester and pentaerythritol tri (meth) acrylic ester will be obtained.

The pentaerythritol (meth) acrylic esters thus obtained are liquid at room temperature, and are pentaerythritol tri (meth) acrylic ester, pentaerythritol di (meth) acrylic ester, pentaerythritol mono (meth) acrylic ester. Partial ester such as ester, and tetraester [pentaerythritol tetra (meth) acrylic ester],
The partial ester / tetraester weight ratio is usually 5
0/50 to 90/10, preferably 60/40 to 90 /
Included in the range of 10.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, for example, pentaerythritol and (meth) acrylic acid ester are mixed with a catalyst such as lithium hydroxide and an organic solvent in which pentaerythritol is soluble, such as dimethylformamide and dimethylsulfoxide. It can be carried out by transesterification with a polar organic solvent containing a nitrogen atom or a sulfur atom, preferably in the presence of a polymerization inhibitor, for example, phenothiazine.

In the above transesterification reaction, a catalytic amount,
By appropriately selecting the reaction time and the like, the ratio of the tetraester body and the partial ester body in the obtained pentaerythritol (meth) acrylic ester can be easily adjusted.

After the completion of the reaction, for example, after neutralizing the catalyst with an acid, the neutralized salt is removed by filtration, and then the unreacted (meth) acrylic acid ester is distilled off under reduced pressure, and if necessary, further. An organic solvent immiscible with water was added to the obtained pentaerythritol (meth) acrylic ester,
It is also possible to raise the degree of purification by operations such as washing with water and concentration.

[0028]

The present invention will be specifically described below with reference to examples and comparative examples, but the contents of the present invention are not limited to the examples. In addition,% in the examples is based on weight unless otherwise specified.

Incidentally, pentaerythritol (meth) in the examples
Composition of acrylic esters [Tetraester (4A)
And the weight ratio of the triester (3A) (4A / 3A)] by gas chromatographic analysis, and the purity [the total content of tetraester (4A) and triester (3A)] was determined by gel permeation chromatography. Each was determined by analysis.

Further, in Table 1, the solvent names used are
The following abbreviations are used. DMF: dimethylformamide, FMA: formamide, NMP: N-methylpyrrolidone, DMSO: dimethylsulfoxide, SUF: tetrahydrothiophene-
1,1-dioxide

Example 1 Pentaerythritol (13.6 g, 0.1 mol) was placed in a glass four-necked flask having a capacity of 300 ml equipped with a reflux condenser, a water separator, an air inlet tube, a thermometer and a stirrer.
34.4 g (0.4 mol) of methyl acrylate, 0.12 g (0.005 mol) of lithium hydroxide monohydrate, 13.6 mg of phenothiazine, and 100 g of dimethylformamide as a solvent were charged. Next, while heating the inside of the flask while blowing nitrogen gas having an oxygen concentration of 7% at a rate of 30 ml / min into this flask, the reaction temperature was kept at 85 ° C. while stirring the inner solution, and the ester was kept for 5 hours. Exchange reaction was performed.

After completion of the reaction, the reaction solution was cooled to room temperature, 0.49 g of concentrated sulfuric acid was added to the reaction solution to neutralize lithium hydroxide as a catalyst, and then lithium sulfate was removed by filtration. Further, the pressure inside the system was reduced to distill off most of the solvent dimethylformamide.

The residue obtained by distilling off the solvent was added to 100 m of toluene.
It was dissolved in 100 ml of water, added with 100 ml of water, stirred for 10 minutes, and allowed to stand for 30 minutes to confirm that it was separated into two layers. The operation was repeated once.

Next, toluene was distilled off under reduced pressure to obtain pentaerythritol acrylic ester which is liquid at room temperature and contains pentaerythritol tetraacrylic ester and pentaerythritol triacrylic ester.
Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

Examples 2 to 5 Pentaerythritol acryl which is liquid at room temperature was prepared in the same manner as in Example 1 except that the same amount of the compound shown in Table 1 was used instead of dimethylformamide as the organic solvent in which pentaerythritol was soluble. Ester was obtained. Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

Example 6 Pentaerythritol acrylic esters which were liquid at room temperature were obtained in the same manner as in Example 1 except that 43.0 g (0.5 mol) of methyl acrylate was used. Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

Example 7 Using 43.0 g (0.5 mol) of methyl acrylate, 8
Pentaerythritol acrylic esters which were liquid at room temperature were obtained in the same manner as in Example 1 except that the transesterification reaction was carried out for a period of time. Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

Examples 8 to 12 Example 1 was repeated except that the compounds shown in Table 1 were used instead of methyl acrylate as the (meth) acrylic acid ester.
In the same manner as above, pentaerythritol acrylic esters which were liquid at room temperature were obtained. Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

Example 13 As a catalyst, 0.12 g of lithium hydroxide monohydrate (0.
Lithium carbonate 0.21 g (0.
Pentaerythritol acrylic esters which are liquid at room temperature were obtained in the same manner as in Example 1 except that (005 mol) was used. Table 1 shows the composition, purity and yield of the obtained pentaerythritol acrylic ester.

[0040]

[Table 1]

Comparative Example 1 A glass four-necked flask having a capacity of 300 ml equipped with a reflux condenser, a water separator, an air inlet tube, a thermometer and a stirrer was charged with 129.6 g (1.8 mol) of acrylic acid and penta. 68 g (5.0 mol) of erythritol, 3-hydroxy-
4-Methyl-benzenesulfonic acid 3.95 g (0.02
1 mol), p-toluenesulfonic acid 7.9 g (0.04
6 g), copper sulfate 0.098 g, and toluene 79.0 g as a solvent were charged. Next, while the nitrogen gas having an oxygen concentration of 7% was blown into the flask at a rate of 30 ml / min, heating in the flask was started to stir the internal solution. The contents reached 90 ° C. in 1 hour, and at this temperature, the dehydration esterification reaction was carried out by heating and stirring the esterified water for 0.5 hour while allowing it to exist in the system, and then allowing the reaction temperature to reach 0.5 hour. The temperature was raised to 110 ° C., and the dehydration esterification reaction was carried out for 2 hours while refluxing at this temperature.

Immediately after completion of the reaction, the reaction solution was cooled to room temperature, then 10.7 g of acrylic acid-containing reaction product water separated during the dehydration esterification reaction was added to the reaction solution, stirred for 10 minutes, and then allowed to stand for 30 minutes. After confirming that the two layers were separated, the lower layer washing water was drawn from the bottom to separate the upper layer solution to obtain crude pentaerythritol acrylic esters.

To the obtained crude pentaerythritol acrylic ester, 18.1 g of 20% sodium hydroxide aqueous solution was added, stirred for 10 minutes, and allowed to stand for 30 minutes to confirm separation into two layers, and then the lower layer was separated and removed. Then, this operation was repeated once again.

Then, 25.0 g of a 7% sodium sulfate aqueous solution was added to this, and the mixture was stirred and allowed to stand, and after confirming that the layers were separated into two layers, the lower layer was separated and removed. Furthermore, the same procedure was repeated except that 25.0 g of water was used instead of the 7% sodium sulfate aqueous solution, and after stirring and standing in the same manner, the lower layer was separated and removed, and this operation was repeated once more to repeat pentaerythritol tetraacrylic ester and pentaerythritol triacryl. Pentaerythritol acrylic esters which are liquid at room temperature and which contain an ester as a main component and other components such as various polymers are obtained.

The composition of the obtained pentaerythritol partial acrylic ester [weight ratio of tetraester (4A) and triester (3A) (4A / 3A)] was 27.
7 / 72.2 was good, but the purity [total content of tetraester and triester] was 36%, and the yield was low, 63%.

Comparative Example 2 An ester exchange reaction was attempted in the same manner as in Example 1 except that n-hexane was used as the organic solvent in the same amount instead of dimethylformamide, but the reaction did not proceed even after 6 hours. , Pentaerythritol acrylic ester could not be obtained.

[0047]

According to the production method of the present invention, pentaerythritol (meth) acrylic esters which are liquid at room temperature and contain a large amount of partial ester such as triester can be easily obtained in high purity and high yield. . Furthermore, it is easy to adjust the ratio of the tetraester body and the partial ester body in the pentaerythritol (meth) acrylic ester.

Claims (7)

[Claims] 1. A process for producing pentaerythritol (meth) acrylic ester, which comprises subjecting pentaerythritol and (meth) acrylic ester to a transesterification reaction in the presence of a catalyst and an organic solvent in which pentaerythritol is soluble. Law. 2. The method according to claim 1, wherein the organic solvent in which pentaerythritol is soluble is a polar organic solvent containing a nitrogen atom or a sulfur atom. 3. The organic solvent in which pentaerythritol is soluble is one or more organic solvents selected from the group consisting of formamide, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and tetrahydrothiophene-1,1-dioxide. A method according to claim 1 or 2. 4. The method according to claim 1, 2 or 3, wherein the catalyst is a basic inorganic lithium compound. 5. The method according to claim 1, 2 or 3, wherein the catalyst is lithium hydroxide. 6. The production method according to claim 1, wherein the (meth) acrylic acid ester is an ester of (meth) acrylic acid and an aliphatic alcohol having 1 to 4 carbon atoms. 7. The production method according to claim 1, wherein the transesterification reaction is carried out in the presence of a polymerization inhibitor.