JP2007001876A - Method for producing (meth)acrylate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a (meth)acrylate from an alkylene oxide adduct of a glycerol-based compound, reducing the production of a polymer as a by-product in a dehydrating esterification process as less as possible, enabling a safe operation improved with its productivity and maintaining a good color tone of the obtained (meth)acrylate so as to be able not to damage the added value as a merchandize. <P>SOLUTION: This method for producing the (meth)acrylate is provided by performing the dehydrating esterification of the alkylene oxide adduct of glycerol or diglycerol with a (meth)acrylic acid in the presence of an acid catalyst and a polymerization inhibitor consisting of a copper compound and a phenol-based compound. As the copper compound, a cuprous halide is preferable, and as the phenol-based compound, hydroquinone or hydroquinone monomethyl ether is preferable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a (meth) acrylate obtained from an alkylene oxide adduct of a glycerin compound, and belongs to the (meth) acrylate production field.

  (Meth) acrylate is industrially produced by dehydrating esterification reaction of (meth) acrylic acid and alcohol in the presence of an acid catalyst. In this case, since the (meth) acryloyl group in the (meth) acrylate is a functional group that is easily polymerized, a polymerization reaction may occur simultaneously in the production process.

In industrial scale production, the co-occurrence of polymerization reactions is a serious problem even in small quantities.
That is, the high molecular weight component generated by the polymerization reaction is generally a highly viscous gel-like substance, and is often difficult to remove by regular washing performed every batch. Therefore, even if the amount of by-product per batch is small, it accumulates every time the batch is overlapped, and finally the reactor is blocked. For this reason, the operation is stopped, the reactor is disassembled, etc., the obstructed polymer is removed, and the parts of the apparatus are thoroughly washed, so that the productivity is remarkably lowered.

  In addition, since the polymerization reaction of the (meth) acryloyl group is an exothermic reaction, if radical polymerization of the reactants and products proceeds continuously in the manufacturing process and a runaway state occurs, a huge amount of heat can be generated in a short time. It will fall into an alarming situation of safety.

Therefore, a method for inhibiting the polymerization of (meth) acryloyl groups has been proposed for a long time in the industrial production of (meth) acrylates.
Specifically, there are a method for performing an esterification reaction in an oxygen-containing atmosphere, a method for performing an esterification reaction by adding a polymerization inhibitor into the reaction solution, and the like (Patent Documents 1 and 2).
By these methods, most of the (meth) acrylates are effective in the polymerization inhibition method, and the frequency that the operation must be stopped due to blockage of the polymer is reduced, and the risk of runaway reaction is avoided to a minimum. can do.

JP 2003-226671 A (Claims) JP 2003-226672 A (Claims)

However, the situation is different when the (meth) acrylate is a (meth) acrylate produced from an alkylene oxide adduct of a glycerin compound.
In the first place, the carbon-hydrogen bond of the ether bond is likely to react with oxygen to form a peroxide structure, and when this is cleaved, a radical is generated, which may cause radical polymerization of the (meth) acryloyl group. In the case where an ether bond and a (meth) acryloyl group are present, polymerization is more likely to occur because both are close to each other. This tendency is particularly remarkable in (meth) acrylates produced from alkylene oxide adducts of glycerin compounds.

When producing such (meth) acrylate having a problem in stability, a method of adding a nitrogen-containing compound such as phenothiazine having a higher polymerization preventing effect as a polymerization inhibitor is known (Patent Document 3).
However, the product (meth) acrylate is colored and loses commercial value in applications where transparency is required. Furthermore, when used in applications such as chemically amplified resist resins, the presence of nitrogen-containing compounds affects the optimal amount of photoacid generator added, so there is a slight difference in nitrogen content between production lots. This causes a fatal defect that the resin cannot be manufactured.

  The present inventor, when producing a (meth) acrylate produced from an alkylene oxide adduct of a glycerin compound, reduced the by-product of the polymer in the dehydration esterification step as much as possible, and a safe operation with improved productivity. In order to find a method for producing (meth) acrylates, the obtained (meth) acrylate can maintain a good color tone and can maintain the added value as a product.

JP 2000-072718 (Claims)

As a result of various studies, the present inventor may use two specific compounds in combination as a polymerization inhibitor and perform an esterification reaction of an alkylene oxide adduct of a glycerin compound and (meth) acrylic acid in the presence thereof. The present invention has been found by finding it effective.
Hereinafter, the present invention will be described in detail.
In the present specification, acrylic acid or methacrylic acid is represented as (meth) acrylic acid, and acrylate or methacrylate is represented as (meth) acrylate.

  In the present invention, alkylene oxide adduct of glycerin or diglycerin (hereinafter referred to as RO adduct) and (meth) acrylic acid are dehydrated and esterified in the presence of an acid catalyst and a polymerization inhibitor comprising a copper compound and a phenolic compound. This is a method for producing (meth) acrylate.

Examples of the alkylene oxide unit in the RO adduct include ethylene oxide and propylene oxide.
As addition number of the alkylene oxide unit in RO adduct, 1-30 are preferable, More preferably, it is 1-10.

As the acid catalyst, those usually used in the production of (meth) acrylates may be used, and sulfuric acid, hydrochloric acid, phosphoric acid, fluoboric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, and cation exchangeability may be used. Examples thereof include resins. Among these, sulfuric acid and p-toluenesulfonic acid are preferable because they are easily available, inexpensive, and excellent in reactivity.
As a ratio of an acidic catalyst, 0.01-10 mol% is preferable with respect to preparation (meth) acrylic acid.

The polymerization inhibitor used in the present invention is composed of a copper compound and a phenol compound.
Copper compounds may be anhydrous or hydrated, cupric halides such as cupric chloride and cupric bromide; halogens such as cuprous chloride and cuprous bromide And cuprous sulfate; copper sulfate; and copper dialkyldithiocarbamates such as copper dimethyldithiocarbamate and copper dibutyldithiocarbamate. Among these, cupric chloride and copper sulfate are preferable because they have a strong polymerization inhibiting action and are inexpensive.
Examples of phenolic compounds include hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethyl. Examples include phenol, 2,6-di-tert-butyl-4-methyl-phenol, 2,4,6-tri-tert-butylphenol and the like. Among these, hydroquinone and hydroquinone monomethyl ether are preferable because they are inexpensive and can be easily removed by neutralization washing after dehydration esterification.
The addition ratio of the polymerization inhibitor is preferably 5 to 20000 wtppm, more preferably 25 to 3000 wtppm, with respect to the reaction solution for both the copper compound and the phenolic compound. When the addition ratio is less than 5 wtppm, the polymerization inhibition effect may be insufficient. On the other hand, when it exceeds 20000 wtppm, the effect is not improved even if added more than this, and the resulting (meth) acrylate is obtained. May cause coloring.
The combined ratio of the copper compound and the phenolic compound is preferably 10 to 90% by mass of the copper compound and 10 to 90% by mass of the phenolic compound based on the total amount of the copper compound and the phenolic compound.

The esterification reaction of the RO adduct and (meth) acrylic acid may be performed according to a conventional method.
Examples thereof include a method in which (meth) acrylic acid and an RO adduct are esterified by heating and stirring in the presence of an acidic catalyst and a polymerization inhibitor.
The reaction ratio of the RO adduct and (meth) acrylic acid adjusts the ratio of (meth) acrylic acid with respect to 1 mol of all hydroxyl groups in the RO adduct, according to the target (meth) acrylate.
The end point of the esterification reaction may be determined by the amount of by-produced water or the like.

The esterification reaction can be carried out without a solvent or using a solvent. However, since the esterification reaction generates water as the reaction proceeds, the use of a solvent capable of removing water azeotropically increases the reaction rate. Is preferable.
Examples of the solvent include aromatic hydrocarbons such as toluene, benzene and xylene; aliphatic hydrocarbons such as n-hexane and cyclohexane and n-heptane; organochlorine compounds such as trichloroethane, tetrachloroethylene and methylchloroform; And ketones such as methyl isobutyl ketone.
The amount of these solvents used is preferably 0.1 to 10 times, more preferably 2 to 5 times, by weight with respect to the reaction raw material.

  The reaction temperature is preferably 65 to 140 ° C., more preferably 75 to 120 ° C. from the viewpoint of shortening the reaction time and preventing polymerization. When the temperature is lower than 65 ° C, the reaction rate may be too slow or the yield may be lowered. When the temperature exceeds 140 ° C, thermal polymerization of (meth) acrylic acid or the obtained (meth) acrylate may occur.

The reaction is preferably carried out at normal pressure or slightly reduced pressure.
In order to prevent thermal polymerization of the raw material (meth) acrylic acid or the resulting (meth) acrylate, the reaction is preferably performed in the presence of oxygen during the esterification reaction. Specific examples include a method of performing an esterification reaction while blowing an inert gas containing oxygen into the reaction solution. Examples of the inert gas include nitrogen and helium, and nitrogen is preferable from the viewpoint of inexpensiveness.
In addition to the polymerization inhibitor as an essential component, other polymerization inhibitors may be used in the reaction as required. Specifically, for example, quinone polymerization inhibitors such as p-benzoquinone and naphthoquinone, thiophenol polymerization inhibitors such as 3-hydroxythiophenol, naphthol polymerization inhibitors such as α-nitroso-β-naphthol, alkyls And amine polymerization inhibitors such as diphenylamine, N, N′-diphenyl-p-phenienamine, and phenothiazine.

  As the reaction apparatus used in the above reaction, those usually used can be used, and examples thereof include a reactor equipped with a stirrer, a thermometer, an air blowing tube and a water separator.

The reaction product obtained by the esterification reaction may be purified according to a conventional method.
Specific examples include a method of neutralizing and washing the reaction solution, separating the aqueous layer, distilling off the reaction solvent under reduced pressure, and filtering as necessary.
The neutralization step is performed for the purpose of removing unreacted (meth) acrylic acid and acid catalyst in the reaction solution. Examples of the neutralization step include a method in which an aqueous alkali solution is added to the reaction solution and stirred.

  The (meth) acrylate obtained by this invention can be used for various uses, for example, coating agents, such as a coating material, ink, a resist, a polymerization raw material, etc. are mentioned.

  According to the present invention, in the case of producing (meth) acrylate from RO adduct and (meth) acrylic acid, the by-product of the polymer can be reduced as much as possible, and the productivity in the production on an industrial scale can be reduced. Enable improved and safe operation. Furthermore, the (meth) acrylate obtained is excellent in color tone.

The present invention relates to a method for producing (meth) acrylate, in which RO adduct and (meth) acrylic acid are subjected to dehydration esterification in the presence of an acid catalyst and a polymerization inhibitor composed of a copper compound and a phenol compound.
The copper compound is preferably cupric halide, and the phenolic compound is preferably hydroquinone or hydroquinone monomethyl ether.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
In the following, “%” means mass%.

[Example 1]
Into a 2 L side necked 4-neck flask equipped with a reflux tube, 500 g of diglycerin ethylene oxide 8 mol adduct, 306 g of acrylic acid, 550 g of toluene, 25.7 g of paratoluenesulfonic acid monohydrate, and chlorinated as a polymerization inhibitor Cup of 1.57 g of cupric (1000 wtppm (hereinafter simply referred to as ppm)) and hydroquinone monomethyl ether (hereinafter referred to as MQ) 1.57 g (1000 ppm with respect to the total amount of the reaction solution), While blowing nitrogen gas containing oxygen, the reaction solution temperature was adjusted to 80 to 100 ° C., and the reaction system pressure was adjusted to 400 to 760 mmHG. A dehydration esterification reaction was carried out for 7 hours while removing generated water out of the system with a Dean-Stark tube.
Although the reaction apparatus used for dehydration esterification and the obtained reaction liquid were observed visually, the production | generation of the polymer was not seen. Further, gel permeation chromatography (device: manufactured by Tosoh Corporation, trade name: HLC-8120GPC, column: TSKgel GMH _XL- L, eluent: THF, detector: RI, hereinafter referred to as GPC) is measured. As a result of calculation according to the following formula, the content of the high molecular weight component was 0.2%.

High molecular weight component content in GPC (%) =
(Sum of peak areas with molecular weight of 30,000 or more in terms of polystyrene) / (sum of all peak areas) × 100

The obtained reaction solution is added to a separatory funnel, washed and separated with pure water, the organic layer is further washed and separated with an aqueous sodium hydroxide solution, and the organic layer is further washed and separated with pure water. Liquid.
Thereafter, 0.4 g of MQ was added to the obtained organic layer, and toluene was removed under reduced pressure at 80 ° C. while blowing nitrogen gas containing oxygen, so that the target diglycerin ethylene oxide adduct tetraacrylate was removed. Obtained. The APHA of the product was 100. The Cu content in the product was 0.03 wtppm as a result of measurement by ICP-MS (apparatus: Agilent Technologies, Inc., Agilent 7500cs type).

○ Example 2 and Comparative Examples 1 to 5
In Example 1, the esterification reaction was performed in the same manner as in Example 1 except that the type and ratio of the polymerization inhibitor were changed to Table 1. In Table 1, HQ means hydroquinone.
Table 1 shows the results of visual observation of the reaction apparatus and the obtained reaction solution. Further, GPC of the reaction solution was measured in the same manner as in Example 1. The results are shown in Table 1.
The obtained reaction solution was treated in the same manner as in Example to obtain diglycerin ethylene oxide-modified tetraacrylate.
The APHA and Cu contents of the product were measured in the same manner as in Example 1. The results are shown in Table 1.

The present invention can be used for the production of (meth) acrylates.

Claims (3)

(Meth) acrylate characterized by dehydrating esterification of glycerin or diglycerin alkylene oxide adduct and (meth) acrylic acid in the presence of an acid catalyst and a polymerization inhibitor comprising a copper compound and a phenolic compound. Manufacturing method. The method for producing a (meth) acrylate according to claim 1, wherein the copper compound is cupric halide. The method for producing a (meth) acrylate according to claim 1 or 2, wherein the phenol compound is hydroquinone or hydroquinone monomethyl ether.