JP2002205971A - Method for purifying (meth)acrylate and (meth)acrylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a (meth)acrylate, which enables the efficient removal of colored impurities by the simple method which can stably be operated, and to obtain the (meth)acrylate. SOLUTION: This method for purifying the (meth)acrylate is characterized by transferring a water-containing (meth)acrylate to a distillation tower A, distilling away vapor containing water and a small amount of the (meth) acrylate, adding a primary and/or secondary amino group-containing compound to the vapor or its condensed liquid, separating the treated condensed liquid into the upper layer comprising the (meth)acrylate and the lower layer consisting mainly of water, returning a part or all of the upper layer to the overhead of the distillation tower, taking out the bottom product containing the (meth) acrylate from the bottom of the distillation tower, transferring the taken bottom product to a second distillation tower E, and then removing the high boiling substances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for purifying a (meth) acrylate and a (meth) acrylate.

[0002]

2. Description of the Related Art As an industrial production method of methyl methacrylate, ACH using acetone cyanohydrin as a raw material is used.
C4 oxidation method in which methacrolein obtained by gas phase catalytic oxidation reaction of a compound having 4 carbon atoms is further subjected to gas phase catalytic oxidation to obtain an esterification reaction between methacrylic acid and methanol. A method of directly obtaining an ester by reacting methacrolein obtained by a phase contact oxidation reaction with methanol is known. In addition, various methacrylic esters are produced by performing an esterification reaction with methacrylic acid and an alcohol obtained by these methods, or performing a transesterification reaction with methyl methacrylate and an alcohol. Various methacrylic esters can also be produced by reacting methacrolein obtained by the above method with an alcohol to directly obtain an ester form.

[0003] Methyl acrylate is synthesized, for example, by a gas phase oxidation method from propylene, or from acetylene, carbon monoxide and methanol in the presence of a nickel catalyst (Reppe method). It can also be synthesized by decomposition of ethylene cyanohydrin with sulfuric acid and methanol. Other acrylates are synthesized using the alcohol instead of methanol in the case of lower esters in the same manner as the synthesis method of methyl acrylate, and synthesized by transesterification with methyl acrylate in the case of higher alkyl esters. Is done.

[0004] The (meth) acrylic acid ester obtained by these methods can be a product of relatively high purity. However, ketones, aldehydes, and other coloring impurities produced by various chemical reactions in the production process are contained in the (meth) acrylic acid ester, though in a very small amount, so that there is a problem that the product is colored. Some coloring agents, such as diacetyl, have low specific volatility, and it is difficult to remove such impurities by ordinary distillation.

As a method of purifying methyl methacrylate to remove these colored impurities, for example, a method of adding a polyamine compound, heating and distilling (JP-A-52-23)
017) or in the presence of at least one non-aromatic 1,2-diamine capable of reducing its content by reacting with diacetyl present as an impurity in methyl methacrylate in the presence of an acid catalyst. Distillation method (JP-A-8
169,862), a method of oxime-forming with a mineral salt of hydroxylamine (JP-A-7-23805).
No. 5), a method of performing a reduction treatment with an aqueous solution of a metal hydrogen complex compound (Japanese Patent Application Laid-Open No. 7-258160), and the like.

[0006] However, in the methods described in JP-A-52-23017 and JP-A-8-169962, the amine compound formed by amine and colored impurities is supplied to the distillation column after a long-term operation. There is a problem that the tower and the reboiler become dirty, and stable operation may not be performed for a long time. Also, Japanese Patent Application Laid-Open No. 7-238055
The method described in Japanese Patent Application Laid-Open No. 7-258160 or Japanese Patent Application Laid-Open No. 7-258160 not only complicates the process, but also has a problem that the removal of the coloring substance is not always sufficient. At present, no method has been found which can remove colored impurities contained in (meth) acrylic acid esters practically, easily, and stably operate for a long period of time.

[0007]

SUMMARY OF THE INVENTION The present invention provides an efficient
Further, it is an object of the present invention to provide a method for purifying a (meth) acrylate and a (meth) acrylate which can remove colored impurities by a simple method and can operate stably for a long period of time.

[0008]

The above object can be solved by the present invention described below. (1) A method for purifying a (meth) acrylate containing at least water, wherein (1a) sending a (meth) acrylate containing water to a distillation column (A), and adding water and a small amount of (meth) acrylate The vapor containing the acrylate ester is distilled off from the top of the column, (1b) the vapor distilled off from the top of the distillation column (A) is condensed by the condenser (B), and the condensate is decanted (C) (1c) Between the top (vapor distilling section) of the distillation column (A) and the decanter (C), the vapor distilled out of the top of the distillation column (A) or its condensate is added to the first liquid. Condensation of vapor distilled from the top of distillation column (A) to which a primary and / or secondary amino group-containing compound is added and (1d) a primary and / or secondary amino group-containing compound is added The solution is decanted (C) and consists mainly of (meth) acrylate And a lower layer mainly composed of water, and part or all of the obtained upper layer mainly composed of (meth) acrylic acid ester is refluxed to the top of the distillation column (A). A bottom liquid containing a (meth) acrylate ester is taken out from the bottom of (A) and sent to a distillation column (E) to remove high-boiling substances from the bottom of the column by removing it from the bottom. A method for purifying a (meth) acrylic ester, comprising distilling the acrylic ester.

At this time, part of the lower layer mainly composed of water obtained in the decanter (C) in the step (1d) is partially removed from the top (vapor distilling part) of the distillation column (A) by the decanter (C). It is preferable to add and circulate the vapor distilled from the top of the distillation column (A) or a condensate thereof during the period. (2) A method for purifying a (meth) acrylate ester containing at least water, wherein (2a) the (meth) acrylate ester containing water is sent to the distillation column (I), and a high-boiling substance is canned from the bottom of the column. And vapors containing water and (meth) acrylate are distilled off from the top of the column, and (2b) the vapor distilled off from the top of the distillation column (I) is removed by a condenser (J). Condensate, send the condensate to the decanter (K),
(2c) Between the top (vapor distilling section) of the distillation column (I) and the decanter (K), the vapor distilled from the top of the distillation column (I) or the condensate thereof is converted into primary and / or condensed liquid. Or a distillation column (I) to which a secondary amino group-containing compound is added and (2d) a primary and / or secondary amino group-containing compound is added.
The condensate of the vapor distilled from the top of the tower is decanted (K)
The upper layer mainly composed of (meth) acrylate and the lower layer mainly composed of water are separated into two layers, and the resulting mainly (meth)
Part of the upper layer made of acrylic ester is distilled column (I)
And the remaining upper layer is sent to the distillation column (M),
(2e) The upper layer mainly composed of (meth) acrylate obtained in the decanter (K) is distilled in the distillation column (M),
The low-boiling substances are distilled off from the top of the column to remove them, the bottoms containing the (meth) acrylate ester are taken out from the bottom of the distillation column (M), and (2f) from the bottom of the distillation column (M) (Meth) acrylic, characterized in that the bottom product taken out is sent to a distillation column (Q) to remove high-boiling substances from the bottom of the column and removed, and (meth) acrylate ester is distilled off from the top of the column. A method for purifying an acid ester.

At this time, a part of the lower layer mainly composed of water obtained in the decanter (K) in the step (2d) is partially removed from the top (vapor distilling part) of the distillation column (I) by the decanter (K). It is preferable to add and circulate the vapor distilled from the top of the distillation column (I) or a condensate thereof during the period. (3) A (meth) acrylic ester purified by the method for purifying a (meth) acrylic ester according to the above (1) or (2).

The method for purifying a (meth) acrylate according to the present invention is preferably applied to the purification of a methacrylate, particularly methyl methacrylate.

[0012]

According to the method for purifying a (meth) acrylic acid ester of the present invention, colored impurities can be efficiently and simply removed, and the distillation column can be operated stably for a long period of time. it can. The (meth) acrylic acid ester purified by this purification method has few colored impurities, and when polymerized into a resin, a resin having excellent transparency can be obtained.

Hereinafter, the present invention will be described in detail.

The (meth) acrylic ester to be purified in the present invention is not particularly limited.
Examples thereof include esters of (meth) acrylic acid and alcohol represented by methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. Here, the (meth) acrylate means an acrylate or a methacrylate. The effect of the present invention is remarkable when applied to a methacrylic ester, particularly methyl methacrylate.

The method of the present invention can be applied (meta)
The acrylic ester may be produced by any method and is not particularly limited. As an industrial production method of methacrylic acid ester, methacrolein obtained by an ACH method using acetone cyanohydrin as a raw material or a gas phase catalytic oxidation reaction of a compound having 4 carbon atoms (isobutane, isobutylene, etc.) is further subjected to gas phase contact. The methacrylic acid obtained by the C4 oxidation method in which the methacrylic acid and the alcohol obtained are subjected to an esterification reaction by oxidation and the gas phase catalytic oxidation reaction of a compound having 4 carbon atoms are reacted with an alcohol using a palladium-containing compound to directly form the ester form And the like are known. As an industrial production method of an acrylic ester, there is known a method in which acrolen obtained by a gas-phase catalytic oxidation reaction of propylene is further subjected to a gas-phase catalytic oxidation, and an esterification reaction between the obtained acrylic acid and an alcohol is performed. ing.

The (meth) acrylic acid ester produced by such a method is usually used as a coloring impurity, for example,
Contains diacetyl, methacrolein, crotonaldehyde, methyl pyruvate and the like. The content varies depending on the production method, production conditions and the like, but is usually 5 to 2 times.
It is about 00 mass ppm.

The purification method of the present invention contains such colored impurities in an amount of 1 to 200 ppm by mass, particularly 10 to 100 ppm by mass (meth).
It is preferably applied to acrylic esters. According to the purification method of the present invention, the content of the colored impurities can be reduced efficiently and easily.

Next, the method for purifying the (meth) acrylate according to the present invention will be described. The method for purifying the (meth) acrylate according to the present invention includes the two methods described above.

The first method of the present invention comprises the step of containing water (meth)
The acrylic ester is distilled, and water condensed from water and a small amount of a (meth) acrylic ester and a low-boiling vapor are distilled off from the top by means of a primary and / or secondary amino group-containing compound. The treatment is performed to separate a layer mainly composed of water, and a part or all of the layer mainly composed of (meth) acrylic acid ester is refluxed to the top of the distillation column, and the (meth) acrylic acid is refluxed from the bottom of the distillation column. The bottom liquid containing the ester is taken out, and the bottom liquid is further distilled to remove high-boiling substances, thereby distilling off the (meth) acrylic acid ester.

The second method of the present invention comprises water-containing (meth)
The acrylic ester is distilled to remove high boilers, and the water condensed from the overhead and the vapor containing the (meth) acrylic ester are separated by a primary and / or secondary amino group-containing compound. The treatment is carried out to separate a layer mainly composed of water, a part of the layer mainly composed of (meth) acrylate is refluxed to the top of the distillation column (I), and the remaining upper layer is further distilled to have a low boiling point. The bottoms containing the (meth) acrylate are removed from the bottom of the distillation column, and the bottoms are further distilled to remove high-boiling substances and to distill the (meth) acrylate. It is something to put out.

In any of the methods for purifying a (meth) acrylate according to the present invention, the water and the condensate of the vapor containing the (meth) acrylate which are distilled from the top of the distillation column are converted to primary and / or Alternatively, the method includes a step of treating with a secondary amino group-containing compound, separating the two layers with a decanter, and separating (meth) acrylic acid ester and water. In the first method, a condensate of vapor distilled off by distillation for removing low-boiling substances is treated with a primary and / or secondary amino group-containing compound, and in the second method, high-boiling substances are removed. The condensate of the vapors distilled off by distillation for the removal of primary is treated with primary and / or secondary amino group containing compounds.

When a primary and / or secondary amino group-containing compound is added to a (meth) acrylic acid ester, a colored impurity mainly having an acetyl group reacts with the amino group-containing compound, and the reaction product is dissolved in water. Therefore, it is removed by separating (meth) acrylate and water by decantation.

The primary and / or secondary used in the present invention
As the secondary amino group-containing compound,

[0024]

Embedded image

There is no particular limitation as long as it has
Any of aromatic amines may be used, and examples thereof include amines having a plurality of amino groups in one molecule, ammonia, hydrazine and derivatives thereof, and further compounds such as hydroxylamine and inorganic acid salts thereof. Examples of the primary and / or secondary amino group-containing compound include, for example, propylamine, butylamine, hexylamine, diethylamine, diethanolamine, diisopropylamine, methylethylamine, ethylenediamine, triethylenetetramine, trimethylenediamine, tetramethylenediamine, Pentamethylenediamine, ethanolamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, phenylenediamine, benzylamine and the like. In particular, it is preferable to use triethylenetetramine, ethylenediamine, trimethylenediamine, or tetramethylenediamine. One or two or more primary and / or secondary amino group-containing compounds may be used.

The amount of the primary and / or secondary amino group-containing compound to be added is 0.00 to the (meth) acrylic acid ester to be treated since the colored impurities can be sufficiently removed.
The content is preferably at least 01% by mass, particularly preferably at least 0.001% by mass, and is preferably at most 5% by mass, particularly preferably at most 1% by mass, based on the (meth) acrylate ester to be treated.

The temperature at which the (meth) acrylic acid ester is treated with the primary and / or secondary amino group-containing compound depends on the reaction rate between the colored impurities and the primary and / or secondary amino group-containing compound. 20 ° C. or higher, preferably 30 ° C. or higher, because the color components can be removed quickly and sufficiently.
100 ° C. from the viewpoint of suppressing the polymerization of the (meth) acrylic ester, avoiding a decrease in the yield, and stably operating the process.
Below, especially 80 ° C or less is preferred.

The treatment time is preferably at least 1 minute, particularly preferably at least 5 minutes, preferably at most 300 minutes, particularly preferably at most 180 minutes.

The treatment step using a primary and / or secondary amino group-containing compound may be carried out by any of a batch system and a continuous system, but is usually carried out by a decanter for a predetermined time at a predetermined temperature. What is necessary is just to hold | maintain and process.

The place where the primary and / or secondary amino group-containing compound is added is between the vapor distillate at the top of the distillation column and the decanter, and contains the primary and / or secondary amino group-containing compound. It is important that the compound does not flow into the distillation column. When a primary and / or secondary amino group-containing compound or an amine compound produced by the reaction of a colored impurity with a primary and / or secondary amino group-containing compound flows into the distillation column, the distillation column or the reboiler Stains on the
It may be difficult to operate stably for a long period of time. However, according to the present invention, almost all of the excess primary and / or secondary amino group-containing compounds and amine compounds are dissolved in the aqueous layer by the decanter and removed together with the aqueous layer to the outside of the system. Can be operated stably for a long period of time.

To this effect, the methacrylic acid ester to be purified may contain water or may further contain water.

The amount of water contained in the purified (meth) acrylate varies depending on the type of (meth) acrylate and the temperature at the time of decantation.
Usually, water is preferably 5 parts by mass or more or 200 parts by mass or less based on 100 parts by mass of the (meth) acrylic acid ester. When the (meth) acrylic ester to be purified does not contain water, or when the water content is small, the (meth) acrylic ester is usually contained so as to contain the amount of water in the above range. Preferably, water is added. When adding water, the place where the water is added is not particularly limited, and it may be added to the (meth) acrylate before being supplied to the distillation column or may be added to the decanter.

The method for producing the (meth) acrylic acid ester to be purified in the present invention is not particularly limited. For example, (meth) acrylic acid ester obtained by esterifying (meth) acrylic acid is used. Specifically, for example, methacrylic acid obtained by gas-phase catalytic oxidation reaction of isobutane, isobutylene, tertiary butyl alcohol, methacrolein and the like is purified by means such as extraction or distillation, and the methacrylic acid is converted to alcohol. Esterification reaction is performed, and methacrylic acid ester obtained by extracting and removing unreacted alcohol from the obtained methacrylic acid ester is used.

The decantation may be performed by a known method. Usually, the treatment with a primary and / or secondary amino group-containing compound is performed in a decanter, so that the residence time in the decanter is 1 minute or more, especially 5 minutes. Minutes or more, preferably 3
It is preferably at most 00 minutes, particularly at most 180 minutes, and the treatment temperature is at least 20 ° C, especially at least 30 ° C, preferably at most 100 ° C, particularly preferably at most 80 ° C.

The type of the distillation column used in the present invention is not particularly limited as long as it is a commonly used distillation column, and examples thereof include a tray type and a packed type. The operating conditions are not particularly limited, and may be appropriately determined according to a known method.

The distillation operation is preferably carried out under reduced pressure from normal pressure, and more preferably under reduced pressure in order to suppress polymerization of monomers.

(Meta) which can be used in the first method of the present invention
One example of an acrylic ester purifying apparatus is shown in FIG. 1, and the first (meth) acrylic ester purifying method of the present invention will be described with reference to the drawing.

The (meth) acrylate containing water to be purified is fed from line (1) to the distillation column (A), where it is mainly composed of water, low boilers and a small amount of (meth) acrylate. And a bottoms containing a (meth) acrylic acid ester. The operating conditions of the distillation column (A) may be appropriately determined as long as low boiling impurities in the (meth) acrylate can be removed.

The vapor (distillate) distilled off from the top of the distillation column (A) is the compound containing the primary and / or secondary amino group supplied from the line (2) and the line (3) Is mixed with a lower layer of a decanter (C) to be described later supplied from the tank and condensed in the condenser (B).

The primary and / or secondary amino group-containing compound and the lower layer of the decanter (C) condense the vapor distilled from the top of the distillation column (A) before the decanter (C). You may add after doing.

The condensate is led to the decanter (C), where the condensate is separated into two layers, an upper layer mainly composed of (meth) acrylate and a lower layer mainly composed of water. Part of the lower layer of the decanter mainly composed of water is mixed again with the vapor distilled from the top of the distillation column (A) from the line (3), and the remaining lower layer is removed from the system from the line (4).

As a result, the excess primary and / or secondary amino group-containing compound and the amine compound formed by the reaction of the colored impurity with the primary and / or secondary amino group-containing compound are: Almost all are dissolved in the lower layer of the decanter, so they are removed out of the system together with the lower layer.

In order to make effective use of the unreacted primary and / or secondary amino group-containing compound, a part of the lower layer is mixed again with the distillate from the top of the distillation column (A). Although preferred, all may be removed from the system. The place where a part of the lower layer is added may be a primary and / or secondary amino group-containing compound or a colored impurity and a primary and / or secondary compound.
If the amine compound produced by the reaction with the secondary amino group-containing compound does not flow into the distillation column, it may be anywhere between the top of the distillation column (A) and the decanter (C).

Further, the distillate and the primary and / or secondary
A stirrer, a filler layer, and the like may be provided in order to efficiently contact the secondary amino group-containing compound.

On the other hand, almost all of the upper layer of the decanter (C) mainly composed of (meth) acrylic acid ester is refluxed to the top of the distillation column (A), and the remaining upper layer is capable of accumulating water-insoluble low-boiling substances. The necessary amount for avoiding is drawn out of the system from the line (5). If it is not necessary to remove the water-insoluble low-boiling substances, all of them may be refluxed to the top of the distillation column (A).

The bottoms of the distillation column (A) containing the (meth) acrylic acid ester from which low-boiling substances and water have been removed are supplied from the line (6) to the distillation column (E). The distillation column (E) is a purification column. Part of the bottoms of the distillation column (A) is refluxed to the distillation column (A) through the reboiler (D). Then, the vapor distilled from the top of the distillation column (E) is condensed in the condenser (F), a part of which is returned to the top of the distillation column (E), and the rest is taken out from the line (7). High purity purified (meth) acrylic acid ester is obtained. on the other hand,
Part of the bottoms containing high-boiling substances such as polymers is refluxed through the reboiler (H) to the distillation column (E), and the remainder may be removed to the outside of the system. You may transfer to the process of collect | recovering (meth) acrylic acid ester. The operating conditions of the distillation column (E) may be determined appropriately.

(Meth) which can be used in the second method of the present invention
FIG. 2 shows an example of an apparatus for purifying an acrylic ester, and the second method for purifying (meth) acrylic ester according to the present invention will be described with reference to the drawing.

The (meth) acrylate containing water to be purified is fed from line (8) to the distillation column (I), where it contains mainly water, low boilers and (meth) acrylate. It is separated into a distillate and a bottom liquid containing a high-boiling substance such as a polymer. Part of the bottoms is refluxed to the distillation column (I) through the reboiler (L), and the remainder may be removed outside the system, or a step of further recovering (meth) acrylate from the bottoms You may move to. The operating conditions of the distillation column (I) may be determined appropriately.

The vapor (distillate) distilled off from the top of the distillation column (I) is the primary and / or secondary amino group-containing compound and the line (1) supplied from the line (9).
It is mixed with the below-mentioned decanter (K) lower layer supplied from 0) and condensed in the condenser (J).

The primary and / or secondary amino group-containing compound and the lower layer of the decanter (K) condense the vapor distilled from the top of the distillation column (I) before the decanter (K). You may add after doing.

The condensed liquid is led to the decanter (K), where it is separated into two layers, an upper layer mainly composed of (meth) acrylate and a lower layer mainly composed of water. A part of the lower layer of the decanter mainly composed of water is mixed again with the vapor distilled from the top of the distillation column (I) from the line (10),
The remaining lower layer is removed from the line (11) to the outside of the system.

As a result, the excess primary and / or secondary amino group-containing compound and the amine compound formed by the reaction of the colored impurities with the primary and / or secondary amino group-containing compound are: Almost all are dissolved in the lower layer of the decanter, so they are removed out of the system together with the lower layer.

In order to effectively utilize the unreacted primary and / or secondary amino group-containing compound, a part of the lower layer is mixed again with the distillate from the top of the distillation column (I). Although preferred, all may be removed from the system. The place where a part of the lower layer is added may be a primary and / or secondary amino group-containing compound or a colored impurity and a primary and / or secondary compound.
If the amine compound produced by the reaction with the secondary amino group-containing compound does not flow into the distillation column, it may be anywhere between the top of the distillation column (I) and the decanter (K).

Also, the distillate and the primary and / or secondary
A stirrer, a filler layer, and the like may be provided in order to efficiently contact the secondary amino group-containing compound.

On the other hand, a part of the upper layer of the decanter (K) mainly composed of (meth) acrylic ester is refluxed to the top of the distillation column (I), and the remaining upper layer is fed from the line (12) to the distillation column (M). Supplied to

The upper layer of the decanter (K) mainly composed of (meth) acrylic ester is a distillation column (M), which mainly contains distillate containing low-boiling substances and (meth) acrylic ester. Separates from the bottoms. The operating conditions of the distillation column (M) may be determined appropriately.

The vapor (distillate) distilled off from the top of the distillation column (M) is condensed in the condenser (N), almost all of which is returned to the top of the distillation column (M), and the remainder is low. The amount necessary to avoid the accumulation of the boil is withdrawn from the line (13) to the outside of the system.

The bottoms of the distillation column (M) containing the (meth) acrylic acid ester from which low-boiling substances have been removed are supplied to the line (1).
4) to the distillation column (Q). The distillation column (Q) is a purification column. Part of the bottoms of the distillation column (M) is refluxed to the distillation column (M) through the reboiler (P). And
The vapor distilled from the top of the distillation column (Q) is condensed in the condenser (R), a part of which is returned to the top of the distillation column (Q), and the remainder is taken out of the line (15) and A purified (meth) acrylic acid ester of a purity is obtained. On the other hand, the bottoms containing high-boiling substances such as polymers are partially reboiler (T)
To the distillation column (Q), and the remainder may be removed to the outside of the system, or may be further transferred to a step of recovering (meth) acrylate from the bottom liquid. Distillation tower (Q)
May be determined as appropriate.

The (meth) acrylate obtained by such a purification method of the present invention has a sufficiently small content of colored impurities.

[0060]

Hereinafter, the present invention will be described in detail with reference to Examples.
The present invention is not limited to this embodiment.

In the examples, methyl methacrylate was used as a representative of the (meth) acrylate, and the concentration of diacetyl, one of the coloring impurities of the (meth) acrylate, was measured. The concentration of diacetyl was measured by an absolute calibration curve method using gas chromatography (GC; GC-17A manufactured by Shimadzu Corporation). In Examples,% and ppm represent% by mass and ppm by mass, respectively, unless otherwise specified. <Example 1> Methacrylic acid obtained by a gas phase catalytic oxidation reaction of isobutylene was purified by extraction and distillation, and an esterification reaction of the obtained methacrylic acid and methanol was performed.
Extraction and distillation from the reaction solution gave crude methyl methacrylate. The obtained crude methyl methacrylate contains water 3.
7%, diacetyl 20 ppm, other compounds 22.0
%, And APHA representing the number of colors was 6.

This crude methyl methacrylate was purified using a (meth) acrylate purifier as shown in FIG.

The obtained methyl methacrylate was supplied at 1000 g / h to a 30-stage Older Shaw distillation column (low boiling removal column) equipped with a condenser and a decanter at the top of the column.
Low boiler removal was performed. The low-boiling tower has a bottom temperature of 86 ° C,
The operation was performed at an operating pressure of 25 kPa and a discharge speed of 995 g / h.

To the vapor distilled from the top of the column, triethylenetetramine was supplied at a rate of 0.2 g / h, and a lower layer of the decanter obtained later was supplied at a rate of 32.9 g / h, and then condensed in a condenser. The condensate was led to a decanter. Then, adjust the stay time in the decanter to 1 hour, 40
The treatment was carried out at a temperature of 1 hour. The obtained lower layer mainly composed of water was added at 32.9 g / h to the vapor distilled from the top of the distillation column and circulated. The upper layer of the decanter mainly composed of methyl methacrylate was refluxed to the top of the total distillation column.

On the other hand, methyl methacrylate from the bottom of the distillation column from which low-boiling substances had been removed was purified by an 10-stage Oldershaw distillation column (purification column) to obtain purified methyl methacrylate. The purification tower has a feed rate of 995 g / h and a top temperature of 5
The operation was performed at 6 ° C., an operating pressure of 20 kPa, and a distillation speed of 711 g / h.

The resulting purified methyl methacrylate had a diacetyl concentration of 3 ppm and a color number of APHA0. Further, the operation was performed for 15 days, but no contamination such as deposits was found on the distillation column and the reboiler. Example 2 Purification of methyl methacrylate was carried out in the same manner as in Example 1 except that ethylenediamine was used instead of triethylenetetramine. As a result, purified methyl methacrylate was obtained at 705 g / h.

The resulting purified methyl methacrylate had a diacetyl concentration of 2 ppm and a color number of APHA0. Further, the operation was performed for 15 days, but no contamination such as deposits was found on the distillation column and the reboiler. Comparative Example 1 In Example 1, except that triethylenetetramine supplied to the vapor distilled from the top of the distillation column (low-boiling column) was previously mixed with methyl methacrylate obtained by the esterification reaction. Purification of methyl methacrylate was performed in the same manner as in Example 1, and purified methyl methacrylate was obtained at 703 g / h.

The diacetyl concentration in the obtained purified methyl methacrylate was 3 ppm, and the color number was APHA0. However, deposits were confirmed on the distillation column and the reboiler 5 days after the start of operation, and after the 15 days of operation,
The distillation column and reboiler were considerably contaminated. Example 3 The methyl methacrylate used in Example 1 was purified using a (meth) acrylic acid ester purifier as shown in FIG.

The methyl methacrylate used in Example 1 was supplied at 1000 g / h to a 30-stage Older Shaw distillation column (high boiling removal column) equipped with a condenser and a decanter at the top to remove high boiling substances. Was done. The high boiling removal tower was operated at a top temperature of 45 ° C., an operating pressure of 19 kPa, and a bottom speed of 212 g / h.

To the vapor distilled from the top of the column, triethylenetetramine was supplied at a rate of 0.2 g / h, and the lower layer of the decanter obtained later was supplied at a rate of 35.7 g / h, and then condensed in a condenser. The condensate was led to a decanter. Then, adjust the stay time in the decanter to 1 hour, 40
The treatment was carried out at a temperature of 1 hour. The obtained lower layer mainly composed of water was added at 35.7 g / h to the vapor distilled from the top of the distillation column and circulated.

On the other hand, a part of the upper layer of the decanter mainly composed of methyl methacrylate is refluxed at 360 g / h to the top of the high boiling removal tower, and the remaining upper layer is at 730 g / h at 30 stages of an Oldershaw distillation column. (Low-boiling removal tower) to remove low-boiling substances. The low boiling removal tower was operated at a bottom temperature of 82 ° C., an operating pressure of 47 kPa, and a bottom speed of 721 g / h.

Then, the bottoms obtained from the bottom of the low boiling removal tower are supplied at 721 g / h to a 10-stage Older Shaw distillation column (purification tower) for purification, and methyl methacrylate is converted at 699 g / h. Obtained. The purification tower was operated at a top temperature of 56 ° C. and an operating pressure of 20 kPa.

The obtained purified methyl methacrylate had a diacetyl concentration of 2 ppm and a color number of APHA0. Further, the operation was performed for 15 days, but no contamination such as deposits was found on the distillation column and the reboiler. <Comparative Example 2> Except that triethylenetetramine supplied to the vapor distilled from the top of the distillation column (high boiling removal column) in Example 3 was previously mixed with methyl methacrylate obtained by the esterification reaction. Purification of methyl methacrylate was performed in the same manner as in Example 3, and purified methyl methacrylate was obtained at 695 g / h.

The resulting purified methyl methacrylate had a diacetyl concentration of 3 ppm and a color number of APHA0. However, four days after the start of operation, deposits were confirmed on the distillation column and the reboiler, and after the end of the 15-day operation,
The distillation column and reboiler were considerably contaminated.

[0075]

According to the method for purifying a (meth) acrylate according to the present invention, a colored impurity can be removed efficiently and simply by a simple method, and furthermore, a stain on a distillation column or a reboiler can be reduced. Long-term stable operation becomes possible. Further, it is possible to obtain a (meth) acrylate having a small content of colored impurities.

[Brief description of the drawings]

FIG. 1 is an example of an apparatus for purifying (meth) acrylate used in the present invention.

FIG. 2 is an example of an apparatus for purifying (meth) acrylate used in the present invention.

[Explanation of symbols]

 A, E, I, M, Q Distillation columns B, F, J, N, R Condenser C, K decanter G, O, S Liquid distributor D, H, L, P, T Reboiler 1 to 16 lines

Continued on the front page (72) Inventor Tomomichi Hino 20-1 Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Technical Research Institute, Inc. (72) Inventor Yoshiyuki Taniguchi 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Inside the Otake Works (72) Inventor Takehiro Marumoto 20-1, Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Otake Works F-term (reference) 4D076 AA12 BB01 CD29 FA12 GA03 HA11 JA03 JA05 4H006 AA02 AC11 BD60 BD84

Claims (7)

[Claims] 1. A method for purifying a (meth) acrylic ester containing at least water, comprising: (1a) sending a (meth) acrylic ester containing water to a distillation column (A); The vapor containing the (meth) acrylic acid ester is distilled off from the top of the column, (1b) the vapor distilled off from the top of the distillation column (A) is condensed by the condenser (B), and the condensate is decanted ( C), and (1c) the vapor or its condensate distilled off from the top of the distillation column (A) between the top of the distillation column (A) and the decanter (C), A secondary amino group-containing compound is added, and (1d) a vapor condensate distilled from the top of the distillation column (A) to which the primary and / or secondary amino group-containing compound is added is decanted ( (C) the upper layer mainly composed of (meth) acrylate and mainly Two layers are separated into a lower layer composed of water and a part or all of the upper layer mainly composed of (meth) acrylate is refluxed to the top of the distillation column (A), and (1e) distillation column (A) The bottoms containing the (meth) acrylic acid ester are taken out from the bottom of the column, sent to the distillation column (E), high boiling substances are removed from the bottom of the column and removed, and the (meth) acrylic acid ester is taken from the top of the column. And a method for purifying a (meth) acrylate ester. 2. A part of the lower layer mainly composed of water obtained in the decanter (C) in the step (1d) is partially separated from the top of the distillation column (A) to the decanter (C). The method for purifying a (meth) acrylic ester according to claim 1, wherein the mixture is added to the vapor or the condensate thereof distilled off from the top of the column (A) and circulated. 3. A method for purifying a (meth) acrylic ester containing at least water, wherein (2a) sending the (meth) acrylic ester containing water to a distillation column (I), The water and the vapor containing the (meth) acrylate are distilled off from the top of the tower,
(2b) The vapor distilled from the top of the distillation column (I) is condensed by the condenser (J), and the condensate is sent to the decanter (K). (2c) From the top of the distillation column (I) A primary and / or secondary amino group-containing compound is added to the vapor or a condensate thereof distilled from the top of the distillation column (I) between the decanter (K), and (2d) primary And / or distillation column (I) to which a secondary amino group-containing compound is added
The condensate of the vapor distilled from the top of the tower is decanted (K)
The upper layer mainly composed of (meth) acrylate and the lower layer mainly composed of water are separated into two layers, and the resulting mainly (meth)
Part of the upper layer made of acrylic ester is distilled column (I)
And the remaining upper layer is sent to the distillation column (M),
(2e) The upper layer mainly composed of (meth) acrylate obtained in the decanter (K) is distilled in the distillation column (M),
The low-boiling substances are distilled off from the top of the column to remove them, the bottoms containing the (meth) acrylate ester are taken out from the bottom of the distillation column (M), and (2f) from the bottom of the distillation column (M) (Meth) acrylic, characterized in that the bottom product taken out is sent to a distillation column (Q) to remove high-boiling substances from the bottom of the column and removed, and (meth) acrylate ester is distilled off from the top of the column. A method for purifying an acid ester. 4. A part of the lower layer mainly composed of water obtained in the decanter (K) in the step (2d) is transferred from the top of the distillation column (I) to the decanter (K). 4. The method for purifying a (meth) acrylic ester according to claim 3, wherein the mixture is added to the vapor or the condensate thereof distilled off from the top of I) and circulated. 5. The (meth) acrylic ester before purification contains at least one compound selected from the group consisting of diacetyl, methacrolein, crotonaldehyde and methyl pyruvate as coloring impurities. The method for purifying a (meth) acrylate according to any one of the above. 6. The method for purifying a (meth) acrylate according to claim 1, wherein the (meth) acrylate is methyl methacrylate. 7. A (meth) acrylate ester purified by the method for purifying a (meth) acrylate ester according to any one of claims 1 to 6.