Method for producing (METH) acrylate

Abstract

Provided is a technique for improving the yield of a (meth) acrylic acid ester. The present invention is a method for producing a (meth) acrylic acid ester, comprising: reacting (meth) acrylic acid with a secondary alcohol in a reactor in the presence of an acid-type esterification catalyst and a polymerization inhibitor; and contacting a liquid L containing an esterified product of the esterification catalyst obtained in the production of the (meth) acrylate with water at a temperature T of 50-105 DEG C (inclusive) in a reactor and / or a retention tank.

Description

Technical Field

[0001] The present invention relates to a method for producing a (meth)acrylate. In particular, the present invention relates to a method for producing a (meth)acrylate by direct esterification of (meth)acrylic acid with a secondary alcohol. Background Art

[0002] It is a well-known technique to produce a (meth)acrylate by an esterification reaction between an alcohol and (meth)acrylic acid. As described below, this reaction is an equilibrium reaction accompanied by the generation of water.

[0003] [Chemical Formula 1]

[0004]

[0005] In order to shift the equilibrium reaction in the direction of the formation of the (meth)acrylate, it is necessary to remove the water generated in the reaction. On the other hand, this reaction is usually accompanied by side reactions that generate impurities. From the viewpoint of obtaining a high-purity (meth)acrylate that meets the technical requirements of a monomer for producing polymers that can be used in many application fields, it is preferable to remove the impurities. Also, for economic reasons, it is preferable to recycle as much as possible the useful products present in the crude reaction mixture, particularly the unreacted reactants and the catalyst, in the process.

[0006] To achieve these purposes, a series of separation / purification processes including a combination of distillation, extraction, and / or decantation are usually carried out, but this process is particularly difficult to carry out due to the presence of azeotropic mixtures and is costly in terms of energy.

[0007] For example, in U.S. Patent No. 6,072,076, a method for producing an alkyl (meth)acrylate by esterification of (meth)acrylic acid with an alkanol having a chain length in the range of 1 or more and 8 or less carbon atoms in the presence of an acid esterification catalyst is disclosed.

[0008] Furthermore, in Japanese Patent Application Laid-Open No. 2014-534972 (corresponding to U.S. Patent Application Publication No. 2015 / 0299093), a method for continuously producing 2-octyl acrylate with very high purity in a high yield is disclosed, which is a method for continuously producing 2-octyl acrylate by direct esterification, and this method includes: using a single reactor, and recycling of useful compounds, for example, on the one hand, unreacted reactants and on the other hand, an acid catalyst (particularly a sulfur-containing acid-type esterification catalyst, especially a sulfonic acid-type acid catalyst). Summary of the Invention

[0009] However, the method disclosed in the specification of U.S. Patent No. 6,072,076 cannot be applied to the production of (meth)acrylate by the esterification reaction of (meth)acrylic acid with a secondary alcohol. As the reason, it can be cited that secondary alcohols are more likely to undergo dehydration reactions that produce olefins and water in the presence of an acid catalyst. The formation of this water will accumulate due to the recycling of at least a part of the aqueous phase generated by the esterification reaction into the system, and there is a risk that the target (meth)acrylate will be more easily decomposed into the secondary alcohol and (meth)acrylic acid by hydrolysis. Also, according to the specification of U.S. Patent No. 6,072,076, the purification of the crude reaction mixture containing the desired (meth)acrylate and the residual alcohol is carried out by distillation in a distillation apparatus with a long residence time in the presence of an acid catalyst. In the case of synthesizing (meth)acrylate using a secondary alcohol, there are technical problems that olefins and water will be generated by this distillation, and in addition, the (meth)acrylate will be decomposed (i.e., the yield of the (meth)acrylate is low).

[0010] In addition, in the technology disclosed in Japanese Patent Application Laid-Open No. 2014-534972 (corresponding to the specification of U.S. Patent Application Publication No. 2015 / 0299093), there is a technical problem that it is difficult to sufficiently suppress the decomposition of the (meth)acrylate (i.e., the yield of the (meth)acrylate is low).

[0011] As described above, in the technologies disclosed in the specification of U.S. Patent No. 6,072,076 and Japanese Patent Application Laid-Open No. 2014-534972 (corresponding to the specification of U.S. Patent Application Publication No. 2015 / 0299093), the yield of the (meth)acrylate cannot be said to be sufficient. Therefore, the present invention has been completed in view of the above circumstances, and its object is to provide a technology for improving the yield of the (meth)acrylate.

[0012] The inventors of the present invention have conducted in-depth research to solve the above technical problems. As a result, it has been found that by bringing the liquid containing the esterified product of the esterification catalyst obtained in the production of the (meth)acrylate into contact with water at a temperature within a specified range in a reactor and / or a retention tank, the above technical problems can be solved, and thus the present invention has been completed.

[0013] That is, the above object is achieved by the following method for producing a (meth)acrylate, the method for producing a (meth)acrylate including: reacting (meth)acrylic acid with a secondary alcohol in a reactor in the presence of an acid-type esterification catalyst and a polymerization inhibitor; and bringing the liquid L containing the esterified product of the esterification catalyst obtained in the production of the (meth)acrylate into contact with water at a temperature T of 50°C or higher and 105°C or lower in the reactor and / or the retention tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram illustrating an embodiment of the (meth)acrylate manufacturing process.

[0015] Figure 2 This is a schematic diagram illustrating another embodiment of the (meth)acrylate manufacturing process.

[0016] Figure 3 This is a schematic diagram illustrating another embodiment of the (meth)acrylate manufacturing process.

[0017] Figure 4 This is a schematic diagram illustrating another embodiment of the (meth)acrylate manufacturing process.

[0018] Figure 5 This is a schematic diagram illustrating another embodiment of the (meth)acrylate manufacturing process.

[0019] Figure 6 This is a schematic diagram illustrating another embodiment of the (meth)acrylate manufacturing process. Detailed Embodiment

[0020] The present invention provides a method for manufacturing a (meth)acrylate, which includes: reacting (meth)acrylic acid with a secondary alcohol in a reactor in the presence of an acid-type esterification catalyst and a polymerization inhibitor; and contacting a liquid L containing an esterified product of the esterification catalyst obtained in the manufacture of the (meth)acrylate with water at a temperature T of 50°C or higher and 105°C or lower in the reactor and / or a retention tank. According to the present invention, the aim is to provide a technique for increasing the yield of the (meth)acrylate.

[0021] Hereinafter, embodiments of the present invention will be described. It should be noted that the present invention is not limited to the following embodiments and various changes can be made within the scope of the claims. In addition, the embodiments described in this specification can be combined arbitrarily to form other embodiments.

[0022] In this specification, contacting a liquid L containing an esterified product of an acid-type esterification catalyst obtained in the manufacture of a (meth)acrylate with water at a temperature T of 50°C or higher and 105°C or lower in a reactor and / or a retention tank is also simply referred to as "warm water treatment".

[0023] In this specification, "acid-type esterification catalyst" is also simply referred to as "esterification catalyst".

[0024] In this specification, "esterified product of an acid-type esterification catalyst" is also simply referred to as "esterified product of the esterification catalyst".

[0025] In this specification, the term “(meth)acryloyl” includes both acryloyl and methacryloyl. Thus, for example, the term “(meth)acrylic acid” includes both acrylic acid and methacrylic acid.

[0026] In this specification, unless otherwise specified, the measurement of physical properties and the like is carried out under the condition of room temperature (25 ± 5°C).

[0027] Unless otherwise specified, the terms used in this specification should be understood to be used in the meanings commonly used in the art. Thus, unless otherwise defined, all the technical terms and chemical technical terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. In case of contradiction, this specification (including the definitions) shall prevail. Throughout this specification, unless otherwise specified, the expressions in the singular form should be understood to also include the concepts in their plural forms. Thus, unless otherwise specified, the articles in the singular form (for example, in the case of English, “a”, “an”, “the”, etc.) should be understood to also include the concepts in their plural forms.

[0028] The present invention is characterized in that, in a reactor and / or a retention tank, a liquid containing an esterified product of an esterification catalyst obtained in the production of (meth)acrylate is brought into contact with water at a temperature within a specified range. By this configuration, the yield of (meth)acrylate can be increased. The detailed mechanism for exerting the above effect is not yet clear, but it is considered as follows.

[0029] The present inventors have found that in the production of (meth)acrylate, when the esterified product of the esterification catalyst is introduced into a product column and subjected to a heat load, it decomposes into an esterification catalyst and a secondary alcohol. It should be noted that the present inventors speculate that the esterified product of the esterification catalyst is formed by the reaction of a secondary alcohol and / or an olefin formed by the intramolecular dehydration reaction of a secondary alcohol with the esterification catalyst.

[0030] In addition, the present inventors have found that there is a tendency that the lower the amount of the secondary alcohol in the product after heat aging obtained by heat aging the product containing (meth)acrylate over time, the higher the yield and purity of (meth)acrylate. It should be noted that the present inventors speculate that in the product column, the esterified product of the esterification catalyst decomposes into an esterification catalyst and a secondary alcohol, which causes the esterification catalyst to dehydrate the secondary alcohol to form an olefin and water. In addition, the generated water hydrolyzes (meth)acrylate to form a secondary alcohol and (meth)acrylic acid, thereby reducing the yield of (meth)acrylate.

[0031] The inventors of the present invention further studied the above facts and speculations in depth, and as a result, it was found that by bringing the liquid of the esterified product containing the esterification catalyst obtained in the production of (meth)acrylate into contact with water at a temperature within a specified range before introducing the (meth)acrylate into the product column, the esterified product of the esterification catalyst is decomposed. By decomposing the esterified product of the esterification catalyst, the esterification catalyst is easily removed. As a result, the decomposition rate of the (meth)acrylate in the product column is reduced, and the yield of the (meth)acrylate as the final product can be increased. It should be noted that the above mechanism is a speculation and does not limit the technical scope of the present invention.

[0032] In this specification, "reactor and / or retention tank" means a reactor, a retention tank, both a reactor and a retention tank, or a tank having the functions of both a reactor and a retention tank (for example, a reactor having the function of a retention tank as shown in Figure 2 and Figure 4 ). In one embodiment of the present invention, the contact of the liquid L containing the esterified product of the esterification catalyst obtained in the production of (meth)acrylate with water at a temperature T of 50°C or higher and 105°C or lower is preferably carried out in a retention tank or a reactor having the function of a retention tank, and more preferably in a retention tank.

[0033] In the reactor and / or retention tank, when the liquid L containing the esterified product of the esterification catalyst obtained in the production of (meth)acrylate (also simply referred to as "liquid L" in this specification) is brought into contact with water, the water can be in a liquid state, a gaseous state (water vapor), or a combination thereof. It should be noted that when the liquid L is brought into contact with water at a temperature within a specified range, for example, the liquid L can be brought into contact with liquid water at a temperature exceeding 100°C under a pressurized environment or the like.

[0034] In one embodiment of the present invention, the method for producing (meth)acrylate may also include: while distilling water (while distilling a mixture containing water), introducing water in a liquid, gaseous, or combined state thereof (i.e., a part or all of the water in contact with the liquid L) into the reactor and / or retention tank.

[0035] As described above, the method for producing (meth)acrylate of the present invention includes: bringing the liquid L into contact with water at a temperature T of 50°C or higher and 105°C or lower in a reactor and / or retention tank. If the temperature T is only lower than 50°C, the yield of the (meth)acrylate is insufficient. If the temperature T is a temperature only exceeding 105°C, it may be disadvantageous in terms of cost.

[0036] The temperature T is not particularly limited, preferably 55°C or higher and 105°C or lower, more preferably 60°C or higher and 105°C or lower, further preferably 65°C or higher and 105°C or lower, further preferably 70°C or higher and 105°C or lower, further preferably 75°C or higher and 105°C or lower, further preferably 80°C or higher and 105°C or lower, further preferably exceeding 80°C and 105°C or lower, further preferably 85°C or higher and 105°C or lower, and particularly preferably 95°C or higher and 105°C or lower. By bringing the liquid L into contact with water at the temperature T within these ranges in the reactor and / or the retention tank, the yield of the (meth)acrylate will be further increased. In addition, the (meth)acrylate can be produced in a shorter time with a high yield.

[0037] In this specification, the temperature T represents "the temperature when the liquid L is brought into contact with water in the reactor and / or the retention tank", specifically, the temperature of the mixture containing the liquid L and water in the reactor and / or the retention tank. The temperature of the mixture containing the liquid L and water in the reactor and / or the retention tank is measured using a thermometer provided in the reactor and / or the retention tank.

[0038] In this specification, "the method for producing a (meth)acrylate includes: bringing the liquid L into contact with water at a temperature T within a specified range in the reactor and / or the retention tank" means "as long as it includes bringing the liquid L into contact with water at a temperature T within this range in the reactor and / or the retention tank, it may further include bringing the liquid L into contact with water at a temperature outside this range in the reactor and / or the retention tank".

[0039] The contact between the liquid L and water in the reactor and / or the retention tank may include: when setting the temperature within a specified range as the set temperature, bringing the liquid L into contact with the water in a state where the temperature T is maintained within the range of the set temperature ±5°C (in this specification, "within the range of the set temperature ±5°C" means "within the range of the set temperature - 5°C or higher and the set temperature + 5°C or lower") for a retention time within a specified range. For example, in the method for producing a (meth)acrylate according to a preferred embodiment of the present invention, the contact between the liquid L and water in the reactor and / or the retention tank includes: when setting the temperature within the range of 55°C or higher and 100°C or lower as the set temperature, bringing the liquid L into contact with the water in a state where the temperature T is maintained within the range of the set temperature ±5°C (in this specification, "within the range of the set temperature ±5°C" means "within the range of the set temperature - 5°C or higher and the set temperature + 5°C or lower") for a retention time of 0.5 hours or longer and 100 hours or shorter.

[0040] In this specification, the holding time means "the time during which the temperature (temperature T) of the mixture containing liquid L and water in the reactor and / or the retention tank remains within the range of the set temperature ±5°C, starting from the time point when the temperature of the mixture reaches within the range of the set temperature ±5°C". The end point of the holding time is the time point when the temperature T changes from within the range of the set temperature ±5°C to outside this range.

[0041] In this specification, when selecting a set temperature, if there are two or more times when the temperature (temperature T) of the mixture containing liquid L and water remains within the range of the set temperature ±5°C with a time interval during which it goes outside this range, the holding time at this set temperature is treated as the sum of two or more times when it remains within the range of the set temperature ±5°C.

[0042] For example, when selecting 90°C as a set temperature, if the time during which the temperature T remains within the range of 85°C or higher and 95°C or lower is only one time, and if this time is 10 hours, then the holding time at the set temperature of 90°C is 10 hours.

[0043] For example, when selecting 90°C as a set temperature, if there are two times when the temperature T remains within the range of 85°C or higher and 95°C or lower with a time interval during which it goes outside this range, and if the two times during which the temperature T remains within the range of 85°C or higher and 95°C or lower are 2 hours and 8 hours respectively, then the holding time at the set temperature of 90°C is 10 hours.

[0044] The set temperature can be changed during the contact of liquid L and water in the reactor and / or the retention tank. That is, only one set temperature can be selected, or two or more can be selected. It should be noted that when changing the set temperature, in the case where two or more identical set temperatures are selected in a non - continuous manner with respect to the time of setting these two or more identical set temperatures, these two or more identical set temperatures are treated as different set temperatures, and the holding time at the set temperature within the specified temperature range is calculated.

[0045] When liquid L and water are brought into contact in the reactor and / or the retention tank, when only one set temperature is selected within the specified temperature range, the holding time at this set temperature becomes the holding time at the set temperature within this specified temperature range.

[0046] For example, when the range of the set temperature is set to be above 55°C and below 100°C, and only one temperature is selected as the set temperature during the contact between the liquid L and water in the reactor and / or the retention tank, and the set temperature is set to 90°C, if the holding time at the set temperature of 90°C (the time above 85°C and below 95°C, i.e., the time when the temperature T is above 85°C and below 95°C) is 10 hours, then the holding time at the set temperature within the range of above 55°C and below 100°C is 10 hours.

[0047] In this specification, during the contact between the liquid L and water in the reactor and / or the retention tank, when changing the set temperature and selecting two or more temperatures as the set temperature, the holding time at the set temperature within the specified temperature range is processed as follows.

[0048] When changing the set temperature, in the case of selecting two or more set temperatures within the specified temperature range, the sum of the holding times at each of the selected set temperatures is processed as the holding time at the set temperature within the specified temperature range. In addition, when changing the set temperature, in the case of selecting one or more set temperatures within the specified temperature range and one or more set temperatures outside the specified temperature range, the sum of the holding times at each of the set temperatures selected within the specified temperature range (in the case where the time is only one, it is that time) is processed as the holding time at the set temperature within the specified temperature range.

[0049] It should be noted that the start and end points of the holding time at each set temperature are the same as those of the holding time. However, part or all of the time from the time point of changing the set temperature until the temperature T first changes outside the range of ±5°C from the set temperature before the change may overlap with part or all of the holding time at other set temperatures. In the case where there is such overlapping time, the holding time at the set temperature within the specified temperature range is processed as the value obtained by subtracting this overlapping time from the sum of the holding times at each of the set temperatures within the specified temperature range.

[0050] The holding time (the holding time at the set temperature within the specified temperature range) is not particularly limited, preferably 0.1 hour or more, more preferably 0.5 hour or more, further preferably 1 hour or more, further preferably 3 hours or more, further preferably 5 hours or more, and particularly preferably 10 hours or more. If within this range, the yield of (meth)acrylate is further increased. The holding time at the set temperature within the specified temperature range is not particularly limited, preferably 100 hours or less, more preferably 70 hours or less, further preferably 50 hours or less, further preferably 40 hours or less, further preferably 30 hours or less, further preferably 20 hours or less, and particularly preferably 10 hours or less. If within these ranges, (meth)acrylate can be produced in a shorter time. It should be noted that as examples of the range of this holding time in the preferred embodiment, any combination selected from these upper and lower limits can be cited. As the range of this holding time in the preferred embodiment, for example, 0.1 hour or more and 100 hours or less, 0.5 hour or more and 100 hours or less, 1 hour or more and 100 hours or less, 3 hours or more and 100 hours or less, 5 hours or more and 100 hours or less, 10 hours or more and 100 hours or less, 1 hour or more and 70 hours or less, 3 hours or more and 70 hours or less, 5 hours or more and 70 hours or less, 10 hours or more and 70 hours or less, 1 hour or more and 50 hours or less, 3 hours or more and 50 hours or less, 5 hours or more and 10 hours or less, 10 hours or more and 50 hours or less, 1 hour or more and 40 hours or less, 3 hours or more and 40 hours or less, 5 hours or more and 10 hours or less, 10 hours or more and 40 hours or less, 1 hour or more and 30 hours or less, 3 hours or more and 30 hours or less, 5 hours or more and 30 hours or less, 10 hours or more and 30 hours or less, 1 hour or more and 20 hours or less, 3 hours or more and 20 hours or less, 5 hours or more and 20 hours or less, 1 hour or more and 10 hours or less, 3 hours or more and 10 hours or less, 5 hours or more and 10 hours or less, etc. are applicable, but this holding time is not limited thereto.

[0051] The set temperature is preferably a temperature in the range of 50°C or higher and 100°C or lower, more preferably a temperature in the range of 55°C or higher and 100°C or lower, further preferably a temperature in the range of 60°C or higher and 100°C or lower, further preferably a temperature in the range of 65°C or higher and 100°C or lower, further preferably a temperature in the range of 70°C or higher and 100°C or lower, further preferably a temperature in the range of 75°C or higher and 100°C or lower, further preferably a temperature in the range of more than 75°C and 100°C or lower, further preferably a temperature in the range of 80°C or higher and 100°C or lower, further preferably a temperature in the range of more than 80°C and 100°C or lower, further preferably a temperature in the range of 85°C or higher and 100°C or lower, further preferably a temperature in the range of 90°C or higher and 100°C or lower, and particularly preferably a temperature in the range of 95°C or higher and 100°C or lower. When the temperature within these ranges is set as the set temperature, by bringing the liquid L into contact with water in the reactor and / or the retention tank in a state where the temperature T is maintained within the range of the set temperature ±5°C (in the range of the set temperature - 5°C or higher and the set temperature + 5°C or lower), the yield of the (meth)acrylate is further increased. In addition, the (meth)acrylate can be produced in a shorter time with a high yield.

[0052] Preferably, only one set temperature is selected. Preferably, there is only one holding time.

[0053] As described above, the contact between the liquid L and water in the reactor and / or the retention tank may include: when a temperature within a specified range is set as the set temperature, bringing the liquid L into contact with the water in a state where the temperature T is maintained within the range of the set temperature ±5°C (in the range of the set temperature - 5°C or higher and the set temperature + 5°C or lower) for a holding time within a specified range. For example, in a preferred embodiment of the present invention, the contact between the liquid L and water in the reactor and / or the retention tank in the method for producing (meth)acrylate includes: when a temperature in the range of 55°C or higher and 100°C or lower is set as the set temperature, bringing the liquid L into contact with the water in a state where the temperature T is maintained within the range of the set temperature ±5°C (in the range of the set temperature - 5°C or higher and the set temperature + 5°C or lower) for a holding time of 0.5 hours or longer and 100 hours or shorter. It should be noted that as long as these embodiments include selecting the set temperature within these temperature ranges and bringing the liquid L into contact with water, they may further include selecting the set temperature outside these temperature ranges and bringing the liquid L into contact with water.

[0054] Examples of preferred combinations of the set temperature and the holding time include: a combination of a set temperature in the range of 50°C or higher and 100°C or lower and a holding time of 0.1 hour or longer and 100 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 55°C or higher and 100°C or lower and a holding time of 0.1 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 55°C or higher and 100°C or lower and a holding time of 0.5 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 55°C or higher and 100°C or lower and a holding time of 1 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 55°C or higher and 100°C or lower and a holding time of 5 hours or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 60°C or higher and 100°C or lower and a holding time of 0.1 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 60°C or higher and 100°C or lower and a holding time of 0.5 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 60°C or higher and 100°C or lower and a holding time of 5 hours or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 65°C or higher and 100°C or lower and a holding time of 0.1 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 65°C or higher and 100°C or lower and a holding time of 0.5 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 65°C or higher and 100°C or lower and a holding time of 1 hour or longer and 70 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 65°C or higher and 100°C or lower and a holding time of 0.1 hour or longer and 50 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature; a combination of a set temperature in the range of 65°C or higher and 100°C or lower and a holding time of 0.5 hour or longer and 50 hours or shorter while maintaining the temperature T within the range of ±5°C of the set temperature;Combinations of a set temperature in the range of above 65°C and below 100°C and a holding time of 3 hours or more and 50 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 65°C and below 100°C and a holding time of 5 hours or more and 70 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 70°C and below 100°C and a holding time of 0.1 hour or more and 50 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 70°C and below 100°C and a holding time of 0.5 hour or more and 50 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 70°C and below 100°C and a holding time of 5 hours or more and 50 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 0.1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 3 hours or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 5 hours or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 0.1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 75°C and below 100°C and a holding time of 5 hours or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 80°C and below 100°C and a holding time of 0.1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature; Combinations of a set temperature in the range of above 80°C and below 100°C and a holding time of 1 hour or more and 40 hours or less while maintaining the temperature T within the range of ±5°C of the set temperature;Combinations of a set temperature within the range of above 80°C and below 100°C and a holding time of 5 hours or more and 40 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 80°C and below 100°C and a holding time of 1 hour or more and 40 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 80°C and below 100°C and a holding time of 3 hours or more and 40 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 80°C and below 100°C and a holding time of 1 hour or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 80°C and below 100°C and a holding time of 5 hours or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 85°C and below 100°C and a holding time of 1 hour or more and 40 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 85°C and below 100°C and a holding time of 3 hours or more and 40 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 85°C and below 100°C and a holding time of 1 hour or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 85°C and below 100°C and a holding time of 5 hours or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 90°C and below 100°C and a holding time of 1 hour or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 90°C and below 100°C and a holding time of 5 hours or more and 30 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 95°C and below 100°C and a holding time of 1 hour or more and 20 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 95°C and below 100°C and a holding time of 3 hours or more and 20 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; combinations of a set temperature within the range of above 95°C and below 100°C and a holding time of 5 hours or more and 20 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature;A combination of a set temperature within the range of above 95°C and below 100°C and a holding time of 1 hour or more and 10 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; a combination of a set temperature within the range of above 95°C and below 100°C and a holding time of 3 hours or more and 10 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature; a combination of a set temperature within the range of above 95°C and below 100°C and a holding time of 5 hours or more and 10 hours or less in a state where the temperature T is maintained within the range of ±5°C of the set temperature, etc., but the combination of the set temperature and the holding time is not limited thereto. It should be noted that the contact between the liquid L and water in the reactor and / or the retention tank may further include selecting a set temperature outside these temperature ranges and bringing the liquid L into contact with water as long as it includes selecting a set temperature within these temperature ranges and bringing the contact between the liquid L and water.

[0055] In one embodiment of the present invention, the contact between the liquid L and water in the reactor and / or the retention tank in the method for producing (meth)acrylate preferably includes: bringing the liquid L into contact with the water for 0.1 hour or more in a state where the temperature T is maintained within the range of 50°C or more and 105°C or less. In this embodiment, the temperature range for maintaining the temperature T is more preferably 55°C or more and 105°C or less, further preferably 65°C or more and 105°C or less, further preferably 75°C or more and 105°C or less, further preferably more than 80°C and 105°C or less, further preferably 85°C or more and 105°C or less, and particularly preferably 95°C or more and 105°C or less. In this embodiment, the time for maintaining the temperature T is more preferably 0.5 hour or more, and further preferably 3 hours or more.

[0056] In one embodiment of the present invention, the contact between the liquid L and water in the reactor and / or the retention tank in the method for producing (meth)acrylate preferably includes at least one selected from the group consisting of the following (i), the following (ii), the following (iii), the following (iv), and the following (v), more preferably includes at least one selected from the group consisting of the following (iii), the following (iv), and the following (v), further preferably includes at least one selected from the group consisting of the following (iv) and the following (v), and particularly preferably includes the following (v):

[0057] (i) bringing the liquid L into contact with the water for 5 hours or more and 70 hours or less in a state where the temperature T is maintained within the range of 55°C or more and 65°C or less;

[0058] (ii) bringing the liquid L into contact with the water for 5 hours or more and 100 hours or less in a state where the temperature T is maintained within the range of 65°C or more and 75°C or less;

[0059] (iii) Keep the temperature T in the range of 75 °C or higher and 85 °C or lower, and contact the liquid L with the water for a time of 0.5 hours or more and 40 hours or less.

[0060] (iv) Keep the temperature T in the range of 85 °C or higher and 95 °C or lower, and contact the liquid L with the water for a time of 0.5 hours or more and 25 hours or less.

[0061] (v) Keep the temperature T in the range of 95 °C or higher and 105 °C or lower, and contact the liquid L with the water for a time of 0.1 hours or more and 10 hours or less.

[0062] In the case of (i) above, the time (the time for contacting the liquid L with the water while keeping the temperature T in the range of 55 °C or higher and 65 °C or lower) is preferably 45 hours or more and 70 hours or less. In the case of (ii), the time (the time for contacting the liquid L with the water while keeping the temperature T in the range of 65 °C or higher and 75 °C or lower) is preferably 35 hours or more and 45 hours or less. In the case of (iii), the time (the time for contacting the liquid L with the water while keeping the temperature T in the range of 75 °C or higher and 85 °C or lower) is preferably 20 hours or more and 40 hours or less, more preferably 25 hours or more and 35 hours or less. In (iv), the time (the time for contacting the liquid L with the water while keeping the temperature T in the range of 85 °C or higher and 95 °C or lower) is preferably 10 hours or more and 25 hours or less. In (vi), the time (the time for contacting the liquid L with the water while keeping the temperature T in the range of 95 °C or higher and 105 °C or lower) is preferably 0.5 hours or more and 10 hours or less, more preferably 1 hour or more and 10 hours or less, further preferably 3 hours or more and 10 hours or less, and particularly preferably 5 hours or more and 10 hours or less.

[0063] In these embodiments, the contact between the liquid L and the water in the reactor and / or the retention tank may further include contacting the liquid L with the water in a state where the temperature T is outside these temperature ranges as long as it includes contacting the liquid L with the water while keeping the temperature T within these temperature ranges.

[0064] If these relationships are satisfied, (meth)acrylate can be produced in a shorter time with a high yield.

[0065] When setting the temperature within a specified range to a set temperature, in the reactor and / or the retention tank, the holding time (the holding time for setting the temperature within the specified range to the set temperature) is not particularly limited with respect to the time starting from the time point when the temperature (temperature T) of the mixture containing liquid L and water first reaches within the range of ±5°C of the set temperature and ending at the time point when the temperature T last changes outside the range of ±5°C of the set temperature from within the range of ±5°C of the set temperature (hereinafter also referred to as "elapsed time"). However, the ratio of the holding time to the elapsed time is preferably 80% or more, more preferably 90% or more, and further preferably 95% or more (upper limit 100%). By having the holding time within this ratio range, the warm water treatment can be carried out efficiently.

[0066] It should be noted that when changing the set temperature and selecting two or more set temperatures within a specified temperature range, the time in the case where the starting point is the time point when the temperature T first reaches within the range of ±5°C of the initially set set temperature within the specified temperature range and the ending point is the time point when the temperature T last changes outside the range of ±5°C of the last set set temperature within the specified temperature range is treated as the elapsed time.

[0067] In the reactor and / or the retention tank, the proportion of the mass of water relative to the total mass of the contacting liquid L and water is not particularly limited, preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, further preferably 25% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more (upper limit: less than 100% by mass). In the reactor and / or the retention tank, the proportion of the mass of water relative to the total mass of the contacting liquid L and water is not particularly limited, preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 60% by mass or less (lower limit: more than 0% by mass). In the reactor and / or the retention tank, the proportion of the mass of water relative to the total mass of the contacting liquid L and water can be, for example, 50% by mass or less, or can be 40% by mass or less. If within these ranges, the decomposition rate of the esterified product of the esterification catalyst increases. In addition, the yield of the (meth)acrylate further increases. And the decomposition rate of the esterified product of the specified esterification catalyst is achieved in a shorter time. Therefore, the productivity of the (meth)acrylate further increases. Thus, as preferred examples of the proportion of the mass of water relative to the total mass of liquid L and water, there can be cited: 10% by mass or more and 90% by mass or less, 15% by mass or more and 85% by mass or less, 20% by mass or more and 80% by mass or less, 25% by mass or more and 80% by mass or less, 30% by mass or more and 80% by mass or less, 20% by mass or more and 60% by mass or less, 25% by mass or more and 60% by mass or less, 30% by mass or more and 60% by mass or less, 40% by mass or more and 60% by mass or less, 30% by mass or more and 50% by mass or less, 30% by mass or more and 40% by mass or less, etc., and the proportion of the mass of water relative to the total mass of liquid L and water is not limited thereto.

[0068] The flash point of the produced (meth)acrylate is not particularly limited. However, for example, in the case of producing 1-methylheptyl acrylate, the flash point of the produced 1-methylheptyl acrylate is preferably 90 °C or higher, more preferably 92 °C or higher, further preferably 93 °C or higher, particularly preferably more than 93 °C (the upper limit is the flash point of pure 1-methylheptyl acrylate). The flash point of the (meth)acrylate can be determined by the Cleveland open cup method.

[0069] The higher the purity of the produced (meth)acrylate, the more preferred it is, and particularly preferably 99.9% by mass or more (upper limit 100% by mass). That is, the production method of (meth)acrylate according to a preferred embodiment of the present invention can produce (meth)acrylate with a purity of 99.9% by mass or more. For example, when the (meth)acrylate is 1-methylheptyl acrylate or 1-methylheptyl methacrylate, the purity of the (meth)acrylate is preferably 99.9% by mass or more, more preferably 99.92% by mass or more, and further preferably 99.94% by mass or more (upper limit 100% by mass).

[0070] In one embodiment of the present invention, the production method of 1-methylheptyl acrylate includes: in a reactor and / or a retention tank, bringing a liquid L containing an esterified product of an esterification catalyst obtained in the production of 1-methylheptyl acrylate into contact with water at a temperature T of 50 °C or higher and 105 °C or lower, and then removing low-boiling substances (such as substances with a boiling point lower than that of 1-methylheptyl acrylate) and high-boiling substances (such as substances with a boiling point higher than that of 1-methylheptyl acrylate) by purification. When the liquid L is a liquid obtained by subjecting a reaction mixture containing 1-methylheptyl acrylate and an esterified product of an esterification catalyst to a neutralization treatment, a water washing treatment, and an organic solvent fractionation treatment (such as toluene fractionation treatment) as needed, the purity of 1-methylheptyl acrylate can be calculated, for example, by the following formula. Here, the liquid L is preferably a liquid obtained by subjecting a reaction mixture containing 1-methylheptyl acrylate and an esterified product of an esterification catalyst to a neutralization treatment, a water washing treatment, and an organic solvent fractionation treatment (such as toluene fractionation treatment).

[0071] [Formula 1]

[0072] Purity of 1-methylheptyl acrylate (% by mass) = 100 - (total content of 2-octene, 2-octanol, and acid components in 1-methylheptyl acrylate (% by mass))

[0073] In the calculation of the above formula, the content of 2-octene in 1-methylheptyl acrylate and the content of 2-octanol in 1-methylheptyl acrylate can be quantified by gas chromatography (GC). In addition, the acid components in 1-methylheptyl acrylate can be quantified by neutralization titration.

[0074] The decomposition rate of the esterified product of the esterification catalyst obtained by bringing the liquid L into contact with water at the temperature T in the reactor and / or the retention tank is not particularly limited, and from the viewpoints of the yield and purity of the (meth)acrylate, the higher the decomposition rate, the more preferred it is.

[0075] Details such as the types and amounts added of (meth)acrylic acid, secondary alcohol, acid-type esterification catalyst, inhibitor, and, if necessary, organic solvent used in the synthesis of the (meth)acrylate in the method for producing the (meth)acrylate of the present invention are the same as those described in the explanation of step (a) below. In addition, details of the reaction such as the reaction conditions of the (meth)acrylate in the method for producing the (meth)acrylate of the present invention are the same as those described in the explanation of step (a) below.

[0076] Hereinafter, with reference to Figures 1 to 6 One embodiment of the method for producing the (meth)acrylate of the present invention will be described. However, the method for producing the (meth)acrylate of the present invention is not limited to the following embodiment.

[0077] One embodiment of the present invention is a method for producing a (meth)acrylate, which includes the following (a), the following (b), the following (c), the following (d), and the following (e). The outline of the manufacturing process of this embodiment is schematically shown as Figure 1 .

[0078] (a) Supply an acid-type esterification catalyst, (meth)acrylic acid, secondary alcohol, and inhibitor (and other components (such as organic solvents, etc.) if used) to the reactor 1, and while reacting the (meth)acrylic acid with the secondary alcohol in the presence of the esterification catalyst and inhibitor, distill the water generated in the esterification reaction from the top of the first distillation column 2 in the form of an azeotropic composition with the secondary alcohol and / or, if used, an organic solvent (secondary alcohol, organic solvent if used, or a combination thereof), condense and allow the obtained distillate to stand, thereby separating it into an oil phase and a water phase. On the other hand, in the reactor 1, obtain a reaction mixture A (step (a)) containing the (meth)acrylate and an esterified product (esterified product of the acid-type esterification catalyst) of the esterification catalyst;

[0079] (b) The reaction mixture A is withdrawn from the bottom of the reactor 1 and supplied to the retention tank 3, where the reaction mixture A is neutralized (neutralization treatment) and washed with water (water washing treatment) to obtain a mixture M1 (mixture after neutralization and water washing). The mixture M1 is separated into an oil phase O1 and an aqueous phase W1. The aqueous phase W1 is removed from the retention tank 3, and the oil phase O1 remains in the retention tank 3. If necessary, the oil phase O1 is subjected to a heat treatment, an organic solvent fractionation treatment, or a combination thereof. In the retention tank 3, while the oil phase (the oil phase O1 or the oil phase O1 that has been subjected to a heat treatment, an organic solvent fractionation treatment, or a combination thereof) (here, this oil phase contains an esterified product of an acid-type esterification catalyst and thus corresponds to the liquid L) is brought into contact with water at a temperature T of 50°C or higher and 105°C or lower, it is allowed to stay to obtain a mixture M2 (mixture after warm water treatment). The mixture M2 is separated into an oil phase O2 and an aqueous phase W2. The aqueous phase W2 is removed from the retention tank 3. If necessary, the oil phase O2 is subjected to a heat treatment, an organic solvent fractionation treatment, or a combination thereof. The gas and / or condensate obtained as needed is recovered from the retention tank 3 (the gas, condensate, or a combination thereof obtained as needed is recovered from the retention tank 3), and the remaining portion in the retention tank 3 (the oil phase O2 or the oil phase O2 that has been subjected to a heat treatment, an organic solvent fractionation treatment, or a combination thereof) is obtained as the reaction mixture B (step (b));

[0080] (c) The reaction mixture B is supplied to the second distillation column 4 for distillation, and is separated into a bottom liquid of the second distillation column 4 containing (meth)acrylate and a recovered alcohol (step (c));

[0081] (d) The bottom liquid of the second distillation column 4 is withdrawn from the bottom of the second distillation column 4 and supplied to the third distillation column 5 for distillation, and is separated into a purified (meth)acrylate as the final product and a bottom liquid of the third distillation column 5. The purified (meth)acrylate is withdrawn from the top of the third distillation column 5 (step (d));

[0082] (e) The bottom liquid of the third distillation column 5 is withdrawn from the bottom of the third distillation column 5 and supplied to the treatment device 6, and is separated into a recovered (meth)acrylate and waste oil (step (e)).

[0083] It should be noted that in this embodiment, it can be used in the same manner as or with appropriate modifications to the conventionally well-known methods, and is not limited to the following embodiments.

[0084] [Step (a)]

[0085] In this step, (meth)acrylic acid, secondary alcohol, an acid-type esterification catalyst, a polymerization inhibitor, and, if necessary, an organic solvent (reaction materials) are supplied to the reactor 1 through the pipe 11a. Compounds other than these may also be further supplied to the reactor 1. It should be noted that in Figure 1 , (meth)acrylic acid, secondary alcohol, an acid-type esterification catalyst, a polymerization inhibitor, and, if necessary, an organic solvent are supplied through the same pipe 11a, or they may be supplied through different pipes. Specifically, (meth)acrylic acid may be directly introduced into the reactor through the pipe 11a, and the acid-type esterification catalyst and the polymerization inhibitor may be directly introduced into the reactor through another pipe (not shown). It is also possible that a part of the secondary alcohol is directly introduced into the reactor through the pipe, and the other part is introduced into the top of the first distillation column 2 through another pipe 11c to ensure reliable reflux of the column. Or, as will be described in detail below, the recovered alcohol (a fluid rich in secondary alcohol) obtained from the second distillation column 4 (the purification stage at the subsequent stage) may be supplied to the reactor 1 through the pipe 11b. Or, as will be described in detail below, the recovered (meth)acrylate obtained from the processing device 6 may be supplied to the reactor 1 through the pipes 64 and 11b.

[0086] Here, as the acid-type esterification catalyst (esterification catalyst), sulfur-containing acid-type esterification catalysts, acidic cation exchange resins, etc. can be cited. Among them, as the sulfur-containing acid-type esterification catalyst, for example, sulfur-containing acid compounds such as sulfuric acid and organic sulfonic acids can be used. As the sulfur-containing acid compound, for example, sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, dodecylsulfonic acid, xylenesulfonic acid, etc. can be used. As the acidic cation exchange resin, it is not limited by resin physical properties such as the structure, crosslinking degree of the resin, or their combination, etc. For example, porous or gel-type strong acidic cation exchange resins, weak acidic cation exchange resins, etc. can be used, and porous or gel-type strong acidic cation exchange resins can be preferably used. As the porous-type strong acidic cation exchange resin, examples include: MSC-1 (manufactured by Dow), PK-208, PK-212, PK-216, PK-220, PK-228 (above, manufactured by Mitsubishi Chemical), AMBERLYST (registered trademark)-16, IR-116, IR-118, IR-122, C-26, C-26TR, C-264, C-265 (above, manufactured by Rohm and Haas), SPC-108, SPC-112 (above, manufactured by Bayer), KC-470 (manufactured by Sumitomo Chemical), etc. In addition, as the gel-type strong acidic cation exchange resin, examples include: HCR-S, HCR-W2, HGR-W2 (above, manufactured by Dow), SK-1B, SK-106, SK-110 (above, manufactured by Mitsubishi Chemical), DUOLITE (registered trademark)C20H, C255LFH (above, manufactured by Rohm and Haas), K1221, K1431 (above, manufactured by Bayer), etc. These esterification catalysts can be used alone or in combination of two or more. Among them, considering operability and cost, the acid-type esterification catalyst is preferably a sulfur-containing acid-type esterification catalyst, preferably sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid. The acid-type esterification catalyst preferably contains a sulfur-containing acid-type esterification catalyst, more preferably contains a sulfur-containing acid compound, further preferably contains at least one compound selected from the group consisting of sulfuric acid and organic sulfonic acids, further preferably contains at least one compound selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, dodecylsulfonic acid, and xylenesulfonic acid, and particularly preferably contains at least one compound selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid.The acid-type esterification catalyst is preferably at least one selected from the group consisting of a sulfur-containing acid-type esterification catalyst and an acidic cation exchange resin, more preferably a sulfur-containing acid-type esterification catalyst, further preferably a sulfur-containing acid compound, further preferably at least one compound selected from the group consisting of sulfuric acid and organic sulfonic acids, further preferably at least one compound selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, dodecylsulfonic acid, and xylenesulfonic acid, and particularly preferably at least one compound selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid. In addition, the addition amount of the esterification catalyst is, for example, 0.5 parts by mass or more and 10 parts by mass or less, preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of (meth)acrylic acid. It should be noted that in the case of using two or more esterification catalysts in combination, the addition amount of the esterification catalyst refers to the total amount of these esterification catalysts.

[0087] The acid-type esterification catalyst (esterification catalyst), particularly the sulfur-containing acid-type esterification catalyst, can be supplied to the reactor as it is or in the form of a solution (such as an aqueous solution). When the acid-type esterification catalyst (esterification catalyst) is supplied to the reactor in the form of a solution (such as an aqueous solution), the concentration of the esterification catalyst in the solution can be, for example, 50% by mass or more and 90% by mass or less, preferably 60% by mass or more and 80% by mass or less, and is not limited to these ranges. It should be noted that in the case of using two or more esterification catalysts in combination, the concentration of the esterification catalyst refers to the total concentration of these esterification catalysts in the solution.

[0088] Acrylic acid or methacrylic acid used as a starting material is produced by known methods. For example, industrially, it is produced from propylene or isobutene. Independent of the use of renewable alcohols, the method for producing (meth)acrylate in one embodiment of the present invention may also cover the use of renewable (meth)acrylic acid during esterification. For example, acrylic acid can be obtained by a method including a step of performing gas-phase oxidation of the obtained acrolein after a first step of dehydration of glycerol used to obtain acrolein from glycerol; or it can also be obtained by dehydrating 2-hydroxypropionic acid (lactic acid) or 3-hydroxypropionic acid and their esters. However, the method for producing (meth)acrylic acid is not limited to these methods. As the (meth)acrylic acid used as a starting material, it preferably contains at least one compound selected from the group consisting of acrylic acid and methacrylic acid. The (meth)acrylic acid may contain acrylic acid or may contain methacrylic acid, and more preferably contains methacrylic acid. Among them, it is preferably acrylic acid or methacrylic acid. The (meth)acrylic acid is preferably acrylic acid or methacrylic acid, and particularly preferably methacrylic acid. The addition amount of the (meth)acrylic acid is, for example, 10 parts by mass or more and 50 parts by mass or less, preferably 20 parts by mass or more and 35 parts by mass or less, based on 100 parts by mass of the total amount of the reaction materials ((meth)acrylic acid, secondary alcohol, acid-type esterification catalyst, inhibitor, and, in the case of addition, the total amount of organic solvent and / or water (organic solvent, water, or a combination thereof)). It should be noted that in the case of adding the (meth)acrylic acid in portions, the addition amount of the (meth)acrylic acid refers to the total amount of the (meth)acrylic acid. In addition, in the case of using acrylic acid and methacrylic acid in combination, the addition amount of the (meth)acrylic acid refers to the total amount of acrylic acid and methacrylic acid.

[0089] As the secondary alcohol, there is no particular limitation. For example, it may include: isopropyl alcohol, 2-pentanol, 3-pentanol, 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 4-octanol, 2-nonanol, 2-decanol, 2-undecanol, 2-dodecanol, 2-tridecanol, 2-tetradecanol, 2-pentadecanol, 2-hexadecanol, 2-heptadecanol, 2-octadecanol, 2-nonadecanol, 2-eicosanol, 2-docosanol, etc. These secondary alcohols can be used alone or in combination of two or more. The secondary alcohol preferably contains at least one compound selected from the group consisting of isopropyl alcohol, 2-pentanol, 3-pentanol, 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 4-octanol, 2-nonanol, 2-decanol, 2-undecanol, 2-dodecanol, 2-tridecanol, 2-tetradecanol, 2-pentadecanol, 2-hexadecanol, 2-heptadecanol, 2-octadecanol, 2-nonadecanol, 2-eicosanol, and 2-docosanol. More preferably, it contains at least one compound selected from the group consisting of 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 4-octanol, and 2-nonanol. Further preferably, it contains 2-octanol. Among them, at least one selected from the group consisting of 2-octanol, 3-octanol, and 4-octanol is preferred, and 2-octanol is particularly preferred. The secondary alcohol is further preferably at least one selected from the group consisting of 2-octanol, 3-octanol, and 4-octanol, further preferably 2-octanol, 3-octanol, or 4-octanol, and particularly preferably 2-octanol. 2-Octanol is a renewable alcohol. Specifically, it is obtained as a by-product of sebacic acid obtained by cracking castor oil and is useful as a bio(1-methylheptyl) acrylate (bio(alkyl) acrylate). That is, in a preferred embodiment of the present invention, the secondary alcohol is 2-octanol. At this time, 1-methylheptyl (meth)acrylate is produced. 1-Methylheptyl (meth)acrylate has the following structure. 1-Methylheptyl (meth)acrylate preferably contains at least one compound selected from the group consisting of 1-methylheptyl acrylate and 1-methylheptyl methacrylate. More preferably, it contains 1-methylheptyl methacrylate. 1-Methylheptyl (meth)acrylate is preferably 1-methylheptyl acrylate or 1-methylheptyl methacrylate, and particularly preferably 1-methylheptyl methacrylate.

[0090] [Chemical formula 2]

[0091] 1-Methylheptyl acrylate

[0092]

[0093] 1-Methylheptyl methacrylate

[0094]

[0095] In addition, the (meth)acrylate is obtained by reacting a secondary alcohol with (meth)acrylic acid in equimolar amounts, but it is preferable to use more of the secondary alcohol. Specifically, the addition amount of the secondary alcohol is substantially equimolar or more with respect to (meth)acrylic acid. For example, it is in the range of 0.9 mol or more and 3.0 mol or less, preferably 1.0 mol or more and 2.0 mol or less, relative to 1 mol of (meth)acrylic acid. It should be noted that when two or more secondary alcohols are used in combination, the addition amount of the secondary alcohols refers to the total amount of these secondary alcohols. As Figure 1 shown, a part of the secondary alcohol is directly introduced into the reactor 1 via the pipe 11a. In addition, a part of the secondary alcohol can also be introduced into the top of the first distillation column 2 via the pipe 11c. Thus, the reflux of the first distillation column 2 can be more reliably achieved.

[0096] The polymerization inhibitor is not particularly limited, and examples thereof include phenothiazine, hydroquinone, p-methoxyphenol, methylhydroquinone, benzoquinone, hydroquinone monomethyl ether, di(tert-butyl)-p-cresol (BHT), p-phenylenediamine, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), p-tert-butylcatechol, di(tert-butyl)catechol, TEMPO derivatives such as OH-TEMPO, 2,6-tert-butyl-4-methylphenol, and copper(II) dibutyldithiocarbamate. These polymerization inhibitors can be used alone or in combination of two or more. The polymerization inhibitor preferably contains at least one compound selected from the group consisting of phenothiazine, hydroquinone, p-methoxyphenol, methylhydroquinone, benzoquinone, hydroquinone monomethyl ether, di(tert-butyl)-p-cresol (BHT), p-phenylenediamine, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), p-tert-butylcatechol, di(tert-butyl)catechol, TEMPO derivatives (such as OH-TEMPO, etc.), 2,6-tert-butyl-4-methylphenol, and copper(II) dibutyldithiocarbamate, and more preferably contains phenothiazine. Among them, phenothiazine is preferred. The polymerization inhibitor is preferably phenothiazine. In addition, the addition amount of the polymerization inhibitor is, for example, in the range of 0.05 parts by mass or more and 5 parts by mass or less, preferably 0.1 parts by mass or more and 2 parts by mass or less, relative to 100 parts by mass of (meth)acrylic acid. It should be noted that when two or more polymerization inhibitors are used in combination, the addition amount of the polymerization inhibitors refers to the total amount of these polymerization inhibitors. The polymerization inhibitor can also be additionally added in a subsequent purification treatment step. In this case, the addition amount of the polymerization inhibitor refers to the total amount of the amount initially added to the reactor and the amount additionally added in the subsequent purification treatment step.

[0097] An esterification catalyst, (meth)acrylic acid, a secondary alcohol, and a polymerization inhibitor are supplied to the reactor. In this case, water generated by the esterification reaction and / or water additionally introduced into the reactor (water generated by the esterification reaction, water additionally introduced into the reactor, or a combination thereof) forms an azeotropic composition with the secondary alcohol.

[0098] Alternatively, in addition to supplying an esterification catalyst, (meth)acrylic acid, a secondary alcohol, and a polymerization inhibitor to the reactor, an organic solvent can also be supplied to the reactor. In this case, water generated by the esterification reaction and / or water additionally introduced into the reactor (water generated by the esterification reaction, water additionally introduced into the reactor, or a combination thereof) forms an azeotropic composition with the secondary alcohol and / or the organic solvent added when in use (the secondary alcohol, the organic solvent added when in use, or a combination thereof). Examples of the organic solvent that can be used when additionally supplying an organic solvent to the reactor include: aliphatic hydrocarbons such as hexane, heptane, pentane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ethers such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, diisopropyl ketone, and methyl isobutyl ketone, etc. These organic solvents can be used alone or two or more of them can be used in combination. The organic solvent preferably contains at least one solvent selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, and ketones, more preferably contains aromatic hydrocarbons, further preferably contains at least one solvent selected from the group consisting of toluene and xylene, and particularly preferably contains toluene. Among them, toluene is preferred. The organic solvent is preferably toluene. It should be noted that the organic solvent does not contain a secondary alcohol.

[0099] In addition, the addition amount of the organic solvent is preferably introduced in a proportion of 10 parts by mass or more and 60 parts by mass or less, more preferably 15 parts by mass or more and 40 parts by mass or less, and further preferably 20 parts by mass or more and 35 parts by mass or less based on 100 parts by mass of (meth)acrylic acid. It should be noted that in the case of using two or more organic solvents in combination, the addition amount of the organic solvent refers to the total amount of these organic solvents.

[0100] After supplying (meth)acrylic acid, secondary alcohol, an esterification catalyst, a polymerization inhibitor, and, if necessary, an organic solvent to a reactor, (meth)acrylic acid and the secondary alcohol are batch-reacted in the reactor in the presence of the esterification catalyst. Herein, the batch reaction conditions are not particularly limited, and the same conditions as those known in the art can be applied. For example, the reaction temperature is preferably 40°C or higher and 120°C or lower, more preferably 50°C or higher and 110°C or lower. In particular, by setting the reaction temperature within the above range, the formation of impurities such as olefins can be effectively suppressed. In addition, the reaction rate can be ensured, and sufficient productivity can be achieved. Regarding the reaction time, as the reaction time after reaching the specified reaction temperature, it is preferably 4 hours or more and 24 hours or less, more preferably 5 hours or more and 15 hours or less. The pressure during the reaction is not particularly limited and can be appropriately selected from atmospheric pressure, reduced pressure, or increased pressure according to the reaction mode. It is preferably atmospheric pressure or reduced pressure, more preferably reduced pressure, and particularly preferably adjusting the pressure (reducing pressure) to reach the above reaction temperature. After the reaction for the specified time, the reaction can be terminated by cooling the reactor.

[0101] The reactor 1 may also be equipped with an external heating unit (such as a heat exchanger), and in this case, it is heated to a specified temperature by this heating unit. In addition, the reactor 1 may also be equipped with a stirrer. In addition, as described below, the esterification reaction is an equilibrium reaction accompanied by the generation of water. Therefore, in order to shift the reaction to the ester formation side, the generated water needs to be removed from the system.

[0102] [Chemical formula 3]

[0103]

[0104] Therefore, the reactor 1 is equipped with a distillation column (the first distillation column) 2. Thereby, the generated water can be distilled out of the system, and the water can be removed from the reaction system. Herein, the first distillation column 2 may be, for example, a packed distillation column or a plate distillation column having a theoretical plate number of 5 or more and 15 or less (for example, about 10). It should be noted that in Figure 1 , the reactor 1 and the first distillation column 2 are described as separate devices, but the reactor 1 and the first distillation column 2 may also be an integrated device.

[0105] As the distillation method in the first distillation column 2, known methods such as simple distillation (e.g., flash distillation), molecular distillation (thin-film distillation), etc. can be used, but it is not particularly limited thereto. At this time, simple distillation refers to batch distillation without a rectification section and can be implemented by a usual apparatus. Molecular distillation (thin-film distillation) can be carried out using a Hickman-type distiller, a falling-film distiller, a rotor tray-type distiller, a wiped-film molecular distiller, etc. The first distillation column 2 can be heated by a heating unit such as a thermosyphon or a forced-circulation external heat exchanger. In this case, it is heated to a specified temperature by this heating unit. When the reactor 1 and the first distillation column 2 are equipped with external heating units, the heating unit of the reactor 1 and the heating unit of the first distillation column 2 can be provided separately or can be the same (shared). The distillation conditions are not particularly limited. The distillation pressure is, for example, under reduced pressure between 30 Torr or more and 850 Torr or less, 30 Torr or more and 650 Torr or less (1 Torr = about 1.3 hPa), etc., or under atmospheric pressure, but it is not limited thereto. The distillation temperature (especially the bottom temperature of the column) is, for example, 40°C or more and 120°C or less, preferably 40°C or more and 110°C or less, more preferably 50°C or more and 100°C or less, etc., but it is not limited thereto. The distillation time is, for example, 4 hours or more and 24 hours or less, preferably 5 hours or more and 15 hours or less, etc., but it is not limited thereto. Under such conditions, the generated water can be efficiently distilled out of the system.

[0106] The water generated by the esterification reaction forms an azeotropic composition with the secondary alcohol and / or the organic solvent (secondary alcohol, the organic solvent added in the case of use, or a combination thereof) used and is distilled out from the top of the first distillation column 2 in the form of a gas. This gas is condensed into a liquid by a condenser (not shown) and put into an intermediate tank (not shown) and allowed to stand, whereby it is separated into an oil phase and a water phase (oil-water separation). A part or all of the oil phase can be put into the first distillation column 2 (not shown) in the form of reflux. A part of the oil phase can also be supplied (recycled) to the reactor 1 via pipes 22a and 11b.

[0107] As described above, in the esterification reaction, a mixture of an azeotropic composition mainly containing a secondary alcohol and / or an organic solvent (secondary alcohol, organic solvent added when in use, or a combination thereof) and water, and a small amount of (meth)acrylic acid is distilled. After condensation, it is separated into two phases, an oil phase and a water phase. Therefore, the reactor 1 and the first distillation column (e.g., a packed distillation column) 2 may also be equipped with a condenser supplied with water (e.g., water at 25°C) and a decanter for receiving the condensed azeotropic composition. The decanter may be a decanter equipped with a system that can automatically remove the generated reaction water by opening a solenoid valve, thereby controlling the lower water phase in a positioned manner. In addition, it may also be operated under reduced pressure by adjusting with a vacuum system.

[0108] In addition, a part of the water phase portion may be discarded, or a part or all of it may be supplied to the retention tank 3 via the pipe 22b. The water phase portion is not re-introduced into the first distillation column 2. Thus, the equilibrium of the esterification reaction can be continuously shifted towards the production side of the (meth)acrylate (i.e., the selectivity and yield can be improved). Alternatively, before the water phase portion is biologically treated and discharged, the secondary alcohol and the (meth)acrylic acid contained at a low concentration may be recovered by performing a distillation treatment.

[0109] Through the above esterification reaction, a reaction mixture (reaction mixture A) containing (meth)acrylate and an esterified product of an acid-type esterification catalyst as a by-product is generated in the reactor 1. This reaction mixture A usually contains, in addition to (meth)acrylate and the esterified product of the acid-type esterification catalyst, unreacted secondary alcohol, unreacted (meth)acrylic acid, an esterification catalyst, a polymerization inhibitor, and other high-boiling by-products, etc. Usually, (meth)acrylate is contained in the reaction mixture A in a proportion of about 50% by mass or more and 95% by mass or less.

[0110] [Step (b)]

[0111] In this step, the reaction mixture A obtained in the step (a) is withdrawn from the bottom of the reactor 1 and supplied to the retention tank 3 via the pipe 31. In addition, the aqueous phase separated from the first distillation column 2 is supplied to the retention tank 3 via the pipe 22b. The aqueous phase is supplied, and water is additionally supplied if necessary. In the retention tank 3, the reaction mixture A is neutralized and washed with water. As a result, the acid components and the base components in the reaction mixture A are removed. In addition, in this step, the mixture M1 obtained by neutralizing and washing the reaction mixture A is separated into an oil phase O1 and an aqueous phase W1. The aqueous phase W1 is removed from the retention tank 3, and the oil phase O1 remains in the retention tank 3. And, in the retention tank 3, while the oil phase O1 is brought into contact with water at a temperature T of 50 °C or higher and 105 °C or lower, it is retained. As a result, the esterified product of the esterification catalyst that is difficult to remove by neutralization and washing with water is decomposed into the esterification catalyst and the secondary alcohol. And, the obtained mixture M2 (the mixture after the warm water treatment) is separated into an oil phase O2 and an aqueous phase W2. The aqueous phase W2 is removed from the retention tank 3. At this time, since the esterification catalyst is present in the aqueous phase W2, the esterified product of the esterification catalyst in the reaction mixture A is removed in the form of the esterification catalyst. Here, the retention tank 3 may be equipped with a stirring device and may be a tank (stirring retention tank) or a mixer that is retained while being stirred. In addition, the retention tank 3 may also be equipped with a heating unit.

[0112] Neutralization is carried out using a base. As a result, the acid components in the reaction mixture A are neutralized. As the base, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate, etc. are used. These bases can be used alone or two or more of them can be used in combination. The base preferably contains at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonium carbonate, and more preferably contains sodium hydroxide. Among them, sodium hydroxide is preferred. The base is preferably sodium hydroxide. In addition, the base can also be used in the form of an aqueous solution. The addition amount of the base is only required to be an amount that can neutralize the remaining acid components in the reaction mixture A, and can be appropriately selected in consideration of the supply amount of the esterification catalyst to the reactor, etc.

[0113] After neutralization, (stop stirring if stirring is being carried out,) the obtained mixture is allowed to stand, whereby the mixture is separated into an oil phase and an aqueous phase (oil-water separation). The aqueous phase part (including the acid components and the base components (base) of the esterification catalyst) is removed to the outside of the system via the pipe 33, and only the oil phase remains in the retention tank 3. (Neutralization step).

[0114] Next, water is introduced into the retention tank 3 and stirred if necessary to remove the alkali remaining in the oil phase (water washing). After the water washing, (if stirring is being carried out, stop the stirring,) and the resulting mixture M1 is allowed to stand, whereby the mixture M1 is separated into an oil phase and a water phase (oil-water separation). Among them, a part of the water phase (water phase W1) (alkali component (alkali)) is removed to the outside of the system via the pipe 33, and only the oil phase (oil phase O1) remains in the retention tank 3. (Water washing process).

[0115] The neutralization process and the water washing process can be carried out in different processes in batch operation respectively, or neutralization and water washing can also be carried out continuously in a continuous extraction tower (the neutralization process and the water washing process can also be carried out continuously in a continuous extraction tower). In addition, the neutralization process and the water washing process can be carried out once respectively, or can also be repeated.

[0116] Through these processes, most or all of the esterification catalyst contained in the reaction mixture A is removed to the outside of the system in the form of the water phase.

[0117] The neutralization treatment and the water washing treatment are preferably carried out at a temperature below 50°C. For example, in the neutralization treatment and the water washing treatment, the liquid temperature of the mixture containing water is preferably a temperature below 50°C.

[0118] The oil phase O1 can also be heated after water washing. When using an organic solvent, it is preferred to heat the oil phase O1 after water washing. The oil phase O1 can also be subjected to a heat treatment after water washing. When using an organic solvent, it is preferred to subject the oil phase O1 to a heat treatment after water washing. (Heating step). The oil phase O1 can also be subjected to an organic solvent fraction cutting treatment after water washing. In this specification, the organic solvent fraction cutting treatment means a treatment for reducing the content of the organic solvent or completely removing the organic solvent. The organic solvent fraction cutting treatment can be carried out, for example, by distilling the oil phase O1. The method of the organic solvent fraction cutting treatment is not particularly limited, and examples thereof include a method including heating. Thereby, the organic solvent can be recovered in the form of a gas and can also be condensed when necessary. The gas or the condensate can also be supplied (recycled) to the reactor 1 via the pipes 32 and 11b. It should be noted that the supply (recycling) of the gas or the condensate is usually carried out batchwise. Regarding the details of the heating method, except that the object of the heat treatment is different, it is the same as the description of the subsequent step (f) (description of the heating of the oil phase after water washing in step (f)). The method of the organic solvent fraction cutting treatment is not particularly limited, and for example, it can include heating the oil phase O1 in the retention tank 3 and performing simple distillation. The pressure in the retention tank 3 is not particularly limited, and for example, it can be slowly depressurized. The pressure in the retention tank 3 can be slowly depressurized from 680 hPa to 90 hPa, for example. In addition, the temperature of the bottom liquid during distillation at this time can rise from 110°C to 130°C, for example, or can also rise from 110°C to 125°C, for example. The removal rate of the organic solvent in the simple distillation is not particularly limited, and for example, it is preferably such that more than 90% by mass of the organic solvent contained in the bottom liquid distills out (removal rate of more than 90%), and more preferably such that more than 95% by mass distills out (removal rate of more than 95%). As the organic solvent fraction cutting treatment, there is no particular limitation, and examples thereof include a toluene fraction cutting treatment, which is a treatment for reducing or completely removing the content of toluene. As the organic solvent fraction cutting step for performing the organic solvent fraction cutting treatment, there is no particular limitation, and examples thereof include a toluene fraction cutting step for performing the toluene fraction cutting treatment. It should be noted that if toluene remains in the bottom liquid, it is more difficult to reduce the pressure (reduce the pressure) in the distillation (distillation in the second distillation column) in step (c). Therefore, it is preferred to use the above temperature to achieve the above removal rate, or to use the oil phase O1 that has undergone the toluene fraction cutting step that takes into account both the temperature and the removal rate to perform the subsequent warm water treatment step. It should be noted that when a heat treatment, an organic solvent fraction cutting treatment, or a combination thereof is performed after the water washing treatment and before the warm water treatment, hereinafter, the oil phase O1 means the oil phase O1 that has undergone a heat treatment, an organic solvent fraction cutting treatment, or a combination thereof.

[0119] After washing with water (after the water washing treatment), or after heat treatment, organic solvent fractionation treatment, or a combination thereof, in the retention tank 3 in which the oil phase O1 is present, the oil phase O1 and water are brought into contact with each other at a temperature T of 50°C or higher and 105°C or lower, and allowed to stay. Thereby, the esterified product of the esterification catalyst that is difficult to remove by neutralization and water washing is decomposed into an esterification catalyst and a secondary alcohol.

[0120] After the oil phase O1 and water are brought into contact with each other at a temperature T of 50°C or higher and 105°C or lower and allowed to stay, (when stirring is carried out, the stirring is stopped,) the obtained mixture M2 is allowed to stand, whereby the mixture M2 is separated into an oil phase O2 and an aqueous phase W2 (oil-water separation). Among them, a part or all (preferably all) of the aqueous phase (aqueous phase W2) part (acid-type esterification catalyst) is removed to the outside of the system via the pipe 33, and the oil phase (oil phase O2) remains in the retention tank 3 (warm water treatment step).

[0121] There may be moisture in the oil phase (oil phase O2) after the warm water treatment, but in the subsequent step (c), the moisture is removed through the same path as the recovered alcohol (fluid rich in secondary alcohol) containing the secondary alcohol. Therefore, it can be considered that there is almost no reduction in the yield of (meth)acrylate caused by the mixing of moisture into the oil phase due to the warm water treatment.

[0122] The oil phase (oil phase O2) after warm water treatment can also be heated. When using an organic solvent, it is preferred to heat the oil phase (oil phase O2) after warm water treatment. The oil phase O2 can also be heat-treated after water washing. When using an organic solvent, it is preferred to heat-treat the oil phase O2 after water washing. (Heating step). When using an organic solvent, the oil phase (oil phase O2) after warm water treatment can also be subjected to an organic solvent fraction cutting treatment. The method of the organic solvent fraction cutting treatment is not particularly limited, and for example, a method including heating can be cited. Thereby, the organic solvent can be recovered in the form of a gas and can also be condensed when necessary. The gas or the condensate can also be supplied (recycled) to the reactor 1 via the pipes 32 and 11b. It should be noted that the supply (recycling) of the gas or the condensate is usually carried out batch by batch. Regarding the details of the heating method, except that the object of the heat treatment is different, it is the same as the description of the subsequent step (f) (description of the heating of the oil phase after water washing in step (f)). The organic solvent fraction cutting treatment can be carried out, for example, by distillation of the oil phase O2. The method of the organic solvent fraction cutting treatment is not particularly limited, and for example, it can include heating the oil phase O2 in the retention tank 3 and performing simple distillation. The pressure in the retention tank 3 is not particularly limited, and for example, it can be slowly reduced in pressure. The pressure in the retention tank 3 can be slowly reduced from 680 hPa to 90 hPa, for example. In addition, the temperature of the bottom liquid during distillation at this time can rise from 110 °C to 130 °C, for example, and can also rise from 110 °C to 125 °C, for example. The removal rate of the organic solvent in the simple distillation is not particularly limited, and for example, it is preferred that more than 90% by mass of the organic solvent contained in the bottom liquid distills out (removal rate of more than 90%), and more preferably more than 95% distills out (removal rate of more than 95%). The organic solvent fraction cutting treatment is not particularly limited, and for example, a toluene fraction cutting treatment can be cited, which is a treatment including reducing the content of toluene or completely removing toluene. The organic solvent fraction cutting step for performing the organic solvent fraction cutting treatment is not particularly limited, and for example, a toluene fraction cutting step for performing the toluene fraction cutting treatment can be cited. It should be noted that if toluene remains in the bottom liquid, it is more difficult to reduce the pressure (reduce the pressure) during the distillation in step (c) (distillation in the second distillation column). Therefore, it is preferred to use the above temperature for the oil phase O2 to achieve the above removal rate, or to perform a toluene fraction cutting step that takes into account both the above temperature and the above removal rate.

[0123] After the neutralization treatment, the water washing treatment, and the warm water treatment, and if necessary, further after the heating treatment, the organic solvent fraction cutting treatment, or a combination thereof, the oil phase (reaction mixture B) containing (meth)acrylate remains in the retention tank 3.

[0124] The production method of (meth)acrylate in a preferred embodiment of the present invention includes: separating a mixture containing the liquid L and water into an organic phase containing (meth)acrylate and an aqueous phase containing an acid-type esterification catalyst by bringing the liquid L in a reactor and / or a retention tank into contact with water, and removing part or all of the aqueous phase.

[0125] In the production method of (meth)acrylic acid in a preferred embodiment of the present invention, the contact between the liquid L in a reactor and / or a retention tank and water includes: using the liquid obtained by subjecting a reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst (such as the reaction mixture A, etc.) to neutralization treatment and water washing treatment as the liquid L, and bringing the liquid (i.e., the liquid obtained by subjecting the following reaction mixture to neutralization treatment and water washing treatment, the reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst) into contact with the water at a temperature T. At this time, it is preferred that the reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst is withdrawn from the reactor, and the liquid L (the liquid obtained by subjecting this reaction mixture to neutralization treatment and water washing treatment) is brought into contact with water in the retention tank. In this embodiment, the liquid L can also be the liquid obtained by subjecting a reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst to neutralization treatment, water washing treatment, and organic solvent fraction cutting treatment (such as toluene fraction cutting treatment, etc.).

[0126] In a more preferred embodiment of the production method of (meth)acrylic acid in the present invention, the contact between the liquid L in a reactor and / or a retention tank and water includes: using the liquid obtained by subjecting a reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst (such as the reaction mixture A, etc.) to neutralization treatment and water washing treatment as the liquid L, and bringing the liquid (i.e., the liquid obtained by subjecting the following reaction mixture to neutralization treatment and water washing treatment, the reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst) into contact with the water at a temperature T; this production method further includes: feeding the reaction mixture (such as the reaction mixture B, etc.) obtained after the treatment including the above contact to a distillation column for distillation. At this time, it is preferred that the reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst is withdrawn from the reactor, and the liquid L (i.e., the liquid obtained by subjecting this reaction mixture to neutralization treatment and water washing treatment) is brought into contact with water in the retention tank. In this embodiment, the liquid L can also be the liquid obtained by subjecting a reaction mixture containing an esterified product of (meth)acrylate and an esterification catalyst to neutralization treatment, water washing treatment, and organic solvent fraction cutting treatment (such as toluene fraction cutting treatment, etc.).

[0127] It should be noted that in this embodiment (including the manufacturing method of the (meth)acrylate of (a), (b), (c), (d), and (e)), as Figure 1 shown, process (a) and process (b) are carried out in different apparatuses. In addition, process (a) and process (b) are carried out batchwise. Therefore, as Figure 2 shown, process (a) and process (b) can also be carried out in one apparatus (another embodiment (I)). That is, in another embodiment (I), the reactor 1 also functions as the retention tank 3 ( Figure 2 "1(3)" in Figure 3 and Figure 4 shown, the aqueous phase or water separated from the first distillation column 2 is supplied to the reaction mixture A in the reactor 1(3) obtained in the process (a) via the pipe 22b after the reaction in the process (a) ends. In this another embodiment (I), the reactor 1 and the retention tank 3 for process (a) and process (b) are integrated (using the reactor 1(3)), and except for this, it is carried out in the same manner as the process (a) and the process (b). In addition, in the case of this another embodiment (I), it may also include: a tank 25 that separately stores the aqueous phase separated from the first distillation column 2 until it is supplied to the reactor 1(3). Or, as Figure 3 and Figure 4 shown, the aqueous phase separated from the first distillation column 2 can also be removed via the pipe 22c (waste water). In this case, water is additionally supplied to carry out process (b) (neutralization process, water washing process, warm water treatment process, and heat treatment, organic solvent fraction cutting process or their combination when necessary). It should be noted that in Figure 3 and Figure 4 , all of the aqueous phase separated from the first distillation column 2 is removed via the pipe 22c, but a part of it can also be removed via the pipe 22c, and the remaining part is supplied to the retention tank 3 or the reactor 1(3) (not shown). In addition, as Figure 2 and Figure 4 shown, it may also be that a part or all of the oil phase (the oil phase obtained by the condensation and / or oil-water separation of the gas distilled from the top of the first distillation column 2, the oil phase obtained by the condensation of the gas distilled from the top of the first distillation column 2, the oil phase obtained by the oil-water separation of the gas or its condensate distilled from the top of the first distillation column 2, or their combination) is supplied (recycled) to the reactor 1(3) via the pipes 22a(32), 11b.

[0128] Through the said process (b), the oil phase (reaction mixture B) is obtained in the retention tank 3 ( Figure 1 , Figure 3 ) or the reactor 1(3) ( Figure 2 , Figure 4 ).

[0129] [Step (c)]

[0130] In this step, the oil phase (reaction mixture B) obtained in the above step (b) is supplied to the second distillation column 4 via the pipe 41 for distillation. Thereby, it is separated into the bottom liquid of the second distillation column 4 containing (meth)acrylate and the recovered alcohol (alcohol-rich fluid) (low-boiling impurities) containing secondary alcohol. As described above, steps (a) and (b) are usually carried out batchwise, but are carried out continuously after this step (continuous operation).

[0131] In the second distillation column 4, the oil phase (reaction mixture B) obtained in the retention tank 3 is distilled. The gas distilled from the top of the column or its condensate contains secondary alcohol, (meth)acrylic acid, and a small amount of (meth)acrylate (low-boiling impurities). Therefore, this gas or condensate can also be supplied (recycled) to the reactor 1 via the pipes 42 and 11b. It should be noted that the supply (recycling) of this gas or condensate (recovered alcohol) is usually carried out batchwise.

[0132] Here, as the distillation method in the second distillation column 4, known methods such as simple distillation (e.g., flash distillation), molecular distillation (thin-film distillation), etc. can be used, but it is not particularly limited thereto. As the second distillation column 4, a packed column and a plate column with a theoretical plate number of 5 or more and 20 or less (e.g., theoretical plate number = about 15) can be used. In addition, the second distillation column 4 can be heated by a heater such as a thermosyphon or a forced-circulation external heat exchanger. At this time, the distillation conditions are not particularly limited. The distillation pressure is, for example, under reduced pressure between 5 Torr and 50 Torr (1 Torr = about 1.3 hPa) or under atmospheric pressure, but is not limited thereto. The distillation temperature (especially the bottom temperature) is, for example, 80°C or higher and 150°C or lower, preferably 100°C or higher and 130°C or lower, etc., but is not limited thereto. Under such conditions, components with lower boiling points (low-boiling impurities mainly containing secondary alcohol) can be efficiently distilled out of the system. If necessary, a polymerization inhibitor can also be introduced from the top of the second distillation column 4. At this time, the polymerization inhibitor can also be used in the form of a solution dissolved in secondary alcohol.

[0133] A fluid (bottom liquid) (reaction mixture C) containing a large amount of (meth)acrylate remains at the bottom of the second distillation column 4.

[0134] The operation after the second distillation column 4 is continuous. However, in this case, since the destination for recycling (returning) the gas or its condensate (recovered alcohol) is for batch operation, this recycling (returning) is also carried out batchwise. On the other hand, the bottom liquid of the second distillation column 4 containing (meth)acrylate is sent to the third distillation column 5 via the pipe 51.

[0135] [Step (d)]

[0136] In this step, the bottoms liquid (reaction mixture C) of the second distillation column 4 obtained in step (c) is withdrawn from the bottom of the second distillation column 4 and supplied to the third distillation column 5 via a pipe 51 for distillation. As a result, the purified (meth)acrylate as the final product distills out from the top of the distillation column 4 via a pipe 52, and the bottoms liquid (bottoms liquid D) remains at the bottom of the third distillation column 5. The purified (meth)acrylate is usually shipped as a product. On the other hand, the bottoms liquid (bottoms liquid D) of the third distillation column 5 contains high-boiling impurities (such as Michael adducts formed by the addition of secondary alcohols to (meth)acrylates, esters of (meth)acrylic acid dimers) and polymerization inhibitors, and is transported to the next step (processing device 6) via a pipe 61.

[0137] Here, as the distillation method in the third distillation column 5, known methods such as simple distillation (e.g., flash distillation), molecular distillation (thin-film distillation), etc. can be used, but it is not particularly limited thereto. For example, a packed column and a plate column with a theoretical plate number of 5 or more and 20 or less (e.g., theoretical plate number = about 5 plates or more and about 10 plates or less) can be used. In addition, the third distillation column 5 can be heated by a heater such as a thermosyphon or a forced-circulation external heat exchanger. At this time, the distillation conditions are not particularly limited. The distillation pressure is, for example, under reduced pressure between 5 Torr and 50 Torr (1 Torr = about 1.3 hPa) or under atmospheric pressure, but is not limited thereto. The distillation temperature (especially the bottom temperature) is, for example, 80°C or more and 150°C or less, preferably 100°C or more and 130°C or less, etc., but is not limited thereto. Under such conditions, the purified (meth)acrylate can be efficiently distilled out of the system. If necessary, a polymerization inhibitor can also be introduced from the top of the third distillation column 5. At this time, the polymerization inhibitor can also be used in the form of a solution dissolved in (meth)acrylate.

[0138] It should be noted that in this embodiment (including the method for manufacturing (meth)acrylate of the above (a), (b), (c), (d), and (e)) Figure 1 as shown, step (c) and step (d) are carried out in different apparatuses, but it can also be Figure 3 as shown, step (c) and step (d) are carried out in one apparatus (another embodiment (II)). That is, in another embodiment (II), the second distillation column 4 and the third distillation column 5 are used as the same apparatus ( Figure 3In the case of “4(5)” in this [description]. In this another embodiment (II), steps (c) and (d) are carried out in one distillation column, and except for this, they are carried out under the same conditions as those described in steps (c) and (d). Here, in the case where steps (c) and (d) are carried out in a batch operation, the oil phase (reaction mixture B) obtained in step (b) is supplied via pipe 41 to the second distillation column 4(5) for distillation (first distillation), and then the bottom liquid (reaction mixture C) remaining at the bottom of the second distillation column 4(5) is distilled (second distillation). The gas or condensate (light-boiling impurities) distilled from the top of the second distillation column 4(5) in step (c) (first distillation) is supplied (recycled) to the reactor 1 via pipes 42 and 11b. Then, through step (d) (second distillation), the distillate line is switched, and the final product, i.e., purified (meth)acrylate, is distilled from the top of the second distillation column 4(5) via pipe 52a. Finally, the bottom liquid (bottom liquid D) remains at the bottom of the second distillation column 4(5). In addition, in the case where steps (c) and (d) are carried out in a continuous operation, similarly, the gas or condensate (light-boiling impurities) distilled from the top of the second distillation column 4(5) in step (c) is supplied (recycled) to the reactor 1 via pipes 42 and 11b, and the purified (meth)acrylate as the final product is distilled from the side line of the second distillation column 4(5) via pipe 52b (side line fraction cutting). Finally, the bottom liquid (bottom liquid D) remains at the bottom of the second distillation column 4(5).

[0139] In addition, the embodiments described in this specification can be combined in any combination to form other embodiments. For example, as Figure 4 shown, it is also possible to combine Figure 2 another embodiment (I) and Figure 3 another embodiment (II) (another embodiment (III)).

[0140] [Step (e)]

[0141] In this step, the bottom liquid (bottom liquid D) of the third distillation column 5 obtained in step (d) is withdrawn from the bottom of the third distillation column 5 and supplied via pipe 61 to the treatment device 6. Thereby, it is separated into the active ingredient (recovered (meth)acrylate) contained in the bottom liquid (bottom liquid D) and waste oil.

[0142] The processing device 6 can be a distillation column. Here, as the distillation method in the processing device 6, well-known methods such as simple distillation (e.g., flash distillation), molecular distillation (thin-film distillation), etc. can be used, but it is not particularly limited thereto. Preferably, the processing device 6 is a molecular distillation column (thin-film distillation column). Alternatively, the processing device 6 can be heated by a heater such as a thermosyphon or a forced-circulation external heat exchanger. At this time, the distillation conditions are not particularly limited. The distillation pressure is, for example, under reduced pressure between 5 Torr and 50 Torr (1 Torr = about 1.3 hPa) or at atmospheric pressure, but is not limited thereto. The distillation temperature (especially the bottom temperature of the column) is, for example, 80°C or higher and 150°C or lower, preferably 100°C or higher and 130°C or lower, etc., but is not limited thereto. Under such conditions, the active ingredient contained in the bottom liquid D (hereinafter sometimes also referred to as the recovered (meth)acrylate) and the waste oil can be efficiently separated.

[0143] The recovered (meth)acrylate separated in the processing device 6 can also be supplied (recycled) to the reactor 1 via the pipes 64 and 11b.

[0144] The recovered (meth)acrylate can also be supplied (recycled) to the retention tank 3 via the pipe 62. The recovered (meth)acrylate supplied (recycled) to the retention tank 3 is used in the same neutralization process, water washing process, and warm water treatment process as in the above-mentioned process (b), and is further used in the heating process, organic solvent fraction cutting process, distillation process, or a combination thereof if necessary. It should be noted that the gas or condensate after these processes can also be supplied (recycled) to the reactor 1.

[0145] After the second distillation column 4, continuous operation is carried out, but the recycling (return) of the recovered (meth)acrylate is a batch operation because the return destination is for batch operation.

[0146] The waste oil separated in the processing device 6 is discarded via the pipe 63.

[0147] The method for manufacturing (meth)acrylate according to another embodiment (IV) of the present invention may further include the following process (f) and the following process (g) in addition to the above-mentioned process (a), process (c), process (d), and process (e). This another embodiment (IV) can improve the yield of (meth)acrylate when the bottom liquid of the second distillation column 4 contains an esterified product of an esterification catalyst. The schematic diagram of the manufacturing process of this another embodiment (IV) is shown as Figure 5 .

[0148] The manufacturing method of (meth)acrylate of another embodiment (V) of the present invention may include the above-mentioned step (a), step (b), step (c), step (d), step (e) and step (g). When the bottoms liquid of the second distillation column 4 contains the esterified product of the esterification catalyst in this another embodiment (V), the yield of (meth)acrylate can be further increased. The schematic diagram of the manufacturing process of this another embodiment (V) is shown as Figure 6 .

[0149] (f) After the step (a) and before the step (c), the reaction mixture A is withdrawn from the bottom of the reactor 1 and supplied to the neutralization and water washing tank 7. In the neutralization and water washing tank 7, the reaction mixture A is neutralized and washed with water. After standing for oil-water separation, the aqueous phase part is removed out of the system through the pipe 73. On the other hand, the remaining part (oil phase part) is subjected to heat treatment, organic solvent fraction cutting treatment or a combination treatment thereof as necessary (for example, when there is an organic solvent, heating is carried out as necessary to distill out the organic solvent), and then the reaction mixture B' is obtained (step (f)).

[0150] After step (f), in step (c), the reaction mixture B' is used instead of the reaction mixture B in the above description, and the rest is the same as the above description.

[0151] (g) In the step (d), after the bottoms liquid of the second distillation column 4 is withdrawn from the bottom of the second distillation column 4 and before being supplied to the third distillation column 5 for distillation, the bottoms liquid of the second distillation column 4 is withdrawn from the bottom of the second distillation column 4 and supplied to the retention tank 3'. While the bottoms liquid of the second distillation column 4 (here, since this bottoms liquid contains the esterified product of the esterification catalyst, it corresponds to the liquid L) is brought into contact with water at a temperature T of 50 °C or higher and 105 °C or lower in the retention tank 3' and allowed to stay therein, the mixture M3 (the mixture after warm water treatment) is obtained. The mixture M3 is separated into an oil phase O3 and an aqueous phase W3. The aqueous phase W3 is removed from the retention tank 3', and the gas or condensate obtained as needed is recovered from the retention tank 3'. As necessary, the remaining part (the oil phase O3) in the retention tank 3' is subjected to heat treatment, organic solvent fraction cutting treatment or a combination thereof, and then it is supplied to the third distillation column 5 instead of the bottoms liquid of the second distillation column 4 (step (g)).

[0152] [Step (f)]

[0153] This step is arranged after step (a) and before step (c). This step is usually carried out in batches. The details of neutralization and water washing in this step are the same as the descriptions of neutralization and water washing in step (b). In this step, the reaction mixture A can also be withdrawn from the bottom of the reactor 1 and supplied to the neutralization and water washing tank 7. After the reaction mixture A is neutralized and washed in the neutralization and water washing tank 7, heat treatment, organic solvent fraction cutting treatment or a combination treatment thereof can be carried out if necessary. In this step, the reaction mixture A can also be withdrawn from the bottom of the reactor 1 and supplied to the neutralization and water washing tank 7. After the reaction mixture A is neutralized and washed in the neutralization and water washing tank 7, the heated gas or its condensate is obtained. After neutralization, the aqueous phase part (including the acid component and the base component (base) of the esterification catalyst) is removed out of the system via the pipe 73, and the oil phase remains in the neutralization and water washing tank 7. In addition, in the water washing treatment, the aqueous phase part (base component (base)) is removed out of the system via the pipe 73, and the remaining part (oil phase) in the neutralization and water washing tank 7 is obtained as the reaction mixture B'.

[0154] The oil phase after water washing (after the water washing treatment) can also be heated. In the case of using an organic solvent, the oil phase after water washing (after the water washing treatment) is preferably heated. Heat treatment can also be carried out on the oil phase after water washing. In the case of using an organic solvent, heat treatment is preferably carried out on the oil phase after water washing. (Heating step). In the case of using an organic solvent, organic solvent fraction cutting treatment can also be carried out on the oil phase after water washing (after the water washing treatment). The method of organic solvent fraction cutting treatment is not particularly limited, and for example, a method including heating can be cited. Thus, the organic solvent can be recovered in the form of a gas and can also be condensed if necessary. The gas or condensate can also be supplied (recycled) to the reactor 1 via the pipes 72 and 11b. It should be noted that the supply (recycling) of the gas or condensate is usually carried out in batches.

[0155] As a method for heating the oil phase after water washing (after the water washing treatment), there is no particular limitation, and it can be heated with a heater or distilled. Preferably, the oil phase after water washing is distilled. As a distillation method when distilling the oil phase after water washing, known methods such as simple distillation (e.g., flash distillation), molecular distillation (thin-film distillation), etc. can be used, but it is not particularly limited thereto. For example, distillation columns such as packed columns and plate columns with a theoretical plate number of 5 or more and 20 or less can be used. The distillation column can be heated by a heater such as a thermosyphon or a forced circulation type external heat exchanger. At this time, the distillation conditions are not particularly limited. The distillation pressure is, for example, carried out under reduced pressure between 5 Torr and 50 Torr (1 Torr = about 1.3 hPa) or at atmospheric pressure, but it is not limited thereto. The distillation temperature (especially the bottom temperature of the column) is, for example, 80 °C or higher and 150 °C or lower, preferably 100 °C or higher and 130 °C or lower, etc., but it is not limited thereto. The distillation time is, for example, 4 hours or more and 24 hours or less, preferably 5 hours or more and 15 hours or less, etc., but it is not limited thereto. Under such conditions, the gas (organic solvent) can be efficiently distilled out of the system.

[0156] The method for cutting the organic solvent fraction has no particular limitation. For example, it may include heating the oil phase in the neutralization and water washing tank 7 and performing simple distillation. The pressure in the neutralization and water washing tank 7 has no particular limitation. For example, it can be slowly depressurized. The pressure in the neutralization and water washing tank 7 can be slowly depressurized from 680 hPa to 90 hPa, for example. In addition, the temperature of the bottom liquid during distillation at this time can rise from 110 °C to 130 °C, for example, or can also rise from 110 °C to 125 °C. The removal rate of the organic solvent in the simple distillation has no particular limitation. For example, it is preferably such that 90 mass% or more of the organic solvent contained in the bottom liquid is distilled out (removal rate of 90 mass% or more), and more preferably 95 mass% or more is distilled out (removal rate of 95 mass% or more). As the treatment for cutting the organic solvent fraction, there is no particular limitation. For example, a toluene fraction cutting treatment can be cited, which is a treatment including reducing the content of toluene or completely removing toluene. As the organic solvent fraction cutting process for performing the organic solvent fraction cutting treatment, there is no particular limitation. For example, a toluene fraction cutting process for performing the toluene fraction cutting treatment can be cited. It should be noted that if toluene remains in the bottom liquid, it is more difficult to reduce the pressure (reduce the pressure) during the distillation (distillation in the second distillation column) in step (c). Therefore, it is preferable to use the above temperature for the oil phase in the neutralization and water washing tank 7 to achieve the above removal rate, or to perform a toluene fraction cutting process that takes into account both the above temperature and the above removal rate.

[0157] After the neutralization treatment and water washing treatment in this step, and if necessary, further through heat treatment, organic solvent fraction cutting treatment or a combination thereof, the oil phase (reaction mixture B') containing (meth)acrylate remains in the neutralization and water washing tank 7.

[0158] Then, in step (c), the oil phase (reaction mixture B') obtained in step (f) is supplied through pipe 41 to the second distillation column 4 for distillation. After step (f), step (c) uses reaction mixture B' instead of reaction mixture B in the above description, and is the same as the above description in other respects.

[0159] [Step (g)]

[0160] This step is carried out in step (d) after the bottom liquid of the second distillation column 4 is withdrawn from the bottom of the second distillation column 4 and before it is supplied to the third distillation column 5 for distillation. This step is usually carried out batchwise. In this step, the bottom liquid of the second distillation column 4 is withdrawn from the bottom of the second distillation column 4 and supplied through pipe 51a to the retention tank 3'. While the bottom liquid of the second distillation column 4 is in contact with water in the retention tank 3' at a temperature T of 50 °C or higher and 105 °C or lower, it is retained. Thereby, the esterified product of the esterification catalyst that is difficult to remove by neutralization and water washing is decomposed into the esterification catalyst and secondary alcohol. And the obtained mixture M3 (the mixture after warm water treatment) is separated into an oil phase O3 and an aqueous phase W3, the aqueous phase W3 is removed from the retention tank 3', and the oil phase (oil phase O3) remains in the retention tank 3'. Part or all (preferably all) of the aqueous phase (aqueous phase W3) is removed to the outside of the system through pipe 35. At this time, since the esterification catalyst is present in the aqueous phase W3, the esterified product of the esterification catalyst in the bottom liquid of the second distillation column 4 is removed in the form of the esterification catalyst (warm water treatment step).

[0161] In addition, the obtained secondary alcohol is recovered in the form of a gas and condensed if necessary. The gas or condensate can also be supplied (recycled) to the reactor 1 through pipes 34 and 11b. It should be noted that the supply (recycling) of the gas or condensate is usually carried out batchwise.

[0162] Here, the retention tank 3' can be equipped with a stirring device and can be a tank (stirring retention tank) or mixer that retains while stirring. In addition, the retention tank 3' can also be equipped with a heating unit. Regarding the details of the warm water treatment in this step, except that the object to be treated and a part of the pipes are different, it is the same as the description of the warm water treatment in step (b).

[0163] There may be moisture in the oil phase (oil phase O3) after warm water treatment, but the moisture can be removed by the side stream fraction cutting and divided wall column (DWC) in step (d) described above. Therefore, it is considered that there is almost no reduction in the yield of (meth)acrylate caused by the mixing of moisture into the oil phase due to warm water treatment.

[0164] It is also possible to heat the oil phase (oil phase O3) after warm water treatment. When using an organic solvent, it is preferred to heat the oil phase (oil phase O3) after warm water treatment. It is also possible to perform a heat treatment on the oil phase O3 after warm water treatment. When using an organic solvent, it is preferred to perform a heat treatment on the oil phase O3 after warm water treatment. (Heating step). When using an organic solvent, it is also possible to perform an organic solvent fraction cutting treatment on the oil phase (oil phase O3) after warm water treatment. The method of the organic solvent fraction cutting treatment is not particularly limited, and examples thereof include a method including heating. Thereby, the secondary alcohol, the organic solvent, or a combination thereof can be recovered in a gaseous form, and condensation can also be performed when necessary. The gas or condensate can also be supplied (recycled) to the reactor 1 via the pipes 34 and 11b. It should be noted that the supply (recycling) of the gas or condensate is usually carried out batch by batch. Regarding the details of the heating method, except that the object of the heat treatment and a part of the pipes are different, it is the same as the description of the heating step of the oil phase after water washing in step (f) (description of the heating method of the oil phase after water washing). The organic solvent fraction cutting treatment can be performed, for example, by distillation of the oil phase O3. The method of the organic solvent fraction cutting treatment is not particularly limited, and for example, it can include heating the oil phase O3 in the retention tank 3' and performing simple distillation. The pressure in the retention tank 3' is not particularly limited, and for example, it can be slowly reduced in pressure. The pressure in the retention tank 3' can be slowly reduced from 680 hPa to 90 hPa, for example. In addition, the temperature of the bottom liquid during distillation at this time can rise from 110 °C to 130 °C, for example, or can also rise from 110 °C to 125 °C, for example. The removal rate of the organic solvent in the simple distillation is not particularly limited, and for example, it is preferred that more than 90% by mass of the organic solvent contained in the bottom liquid is distilled out (removal rate of more than 90%), and more preferably more than 95% is distilled out (removal rate of more than 95%). The organic solvent fraction cutting treatment is not particularly limited, and examples thereof include a toluene fraction cutting treatment, which is a treatment including reducing the content of toluene or completely removing toluene. The organic solvent fraction cutting step for performing the organic solvent fraction cutting treatment is not particularly limited, and examples thereof include a toluene fraction cutting step for performing a toluene fraction cutting treatment. It should be noted that if toluene remains in the bottom liquid, it is more difficult to reduce the pressure (reduce the pressure) in the next distillation step. Therefore, it is preferred to use the above temperature for the oil phase O3 to achieve the above removal rate, or to perform a toluene fraction cutting step that takes into account both the above temperature and the above removal rate. It should be noted that in the case of performing a heat treatment, an organic solvent fraction cutting treatment, or a combination thereof after warm water treatment, hereinafter, the oil phase O3 represents the oil phase O3 that has undergone a heat treatment, an organic solvent fraction cutting treatment, or a combination thereof.

[0165] After the warm water treatment, and if necessary, after heat treatment, organic solvent fractionation treatment, or a combination thereof, the remaining portion (oil phase O3) remains in the retention tank 3'. The remaining portion (oil phase O3) in the obtained retention tank 3' is supplied to the third distillation column 5 via the pipe 51b in place of the bottom liquid of the second distillation column 4.

[0166] In Figure 5 In the manufacturing process of, generally, the steps (a), (f), and (g) are carried out batchwise, and the steps (c), (d), and (e) are carried out continuously. In this case, intermediate tanks can also be provided respectively between the step (c) and the step (g) and between the step (g) and the step (d).

[0167] In Figure 6 In the manufacturing process of, generally, the steps (a), (b), and (g) are carried out batchwise, and the steps (c), (d), and (e) are carried out continuously. In this case, intermediate tanks can also be provided respectively between the step (c) and the step (g) and between the step (g) and the step (d).

[0168] The method for manufacturing a (meth)acrylate according to an embodiment of the present invention preferably further includes: subjecting a reaction mixture (such as the reaction mixture A, etc.) containing an esterified product of a (meth)acrylate and an esterification catalyst to a treatment including neutralization treatment and water washing treatment; and distilling the reaction mixture (such as the reaction mixture B, the reaction mixture B', etc.) obtained after the treatment including the neutralization treatment and the water washing treatment to obtain a distilled liquid; the contact between the liquid L and the water in the reactor and / or the retention tank includes: using the distilled liquid as the liquid L and bringing the distilled liquid into contact with the water in the retention tank at the temperature T. At this time, preferably, the reaction mixture containing the esterified product of the (meth)acrylate and the esterification catalyst is withdrawn from the reactor. The method for manufacturing a (meth)acrylate preferably further includes: distilling the treated liquid in the retention tank including the contact between the distilled liquid and the water. The treatment including the neutralization treatment and the water washing treatment can be only the neutralization treatment and the water washing treatment, or can include, in addition to the neutralization treatment and the water washing treatment, other treatments other than the neutralization treatment and the water washing treatment. The treatment including the neutralization treatment and the water washing treatment can be, for example, a treatment including neutralization treatment, water washing treatment, and organic solvent fractionation treatment (such as toluene fractionation treatment, etc.).

[0169] The method for producing a (meth)acrylate according to an embodiment of the present invention more preferably further includes: subjecting a reaction mixture (such as the reaction mixture A, etc.) containing an esterified product of a (meth)acrylate and an esterification catalyst to a treatment including a neutralization treatment and a water washing treatment; feeding the reaction mixture (such as the reaction mixture B, the reaction mixture B', etc.) obtained after the treatment including the neutralization treatment and the water washing treatment to a distillation column for distillation; and withdrawing the bottom liquid of the distillation column from the bottom of the distillation column; the contact between the liquid L in the reactor and / or the retention tank and water includes: using the bottom liquid as the liquid L and bringing the bottom liquid into contact with the water in the retention tank at the temperature T. At this time, it is preferable to withdraw a reaction mixture containing an esterified product of a (meth)acrylate and an esterification catalyst from the reactor. The method for producing a (meth)acrylate preferably further includes: feeding the bottom liquid after the treatment including the contact between the bottom liquid and water in the retention tank to another distillation column for distillation. The treatment including the neutralization treatment and the water washing treatment may be only the neutralization treatment and the water washing treatment, or may include treatments other than the neutralization treatment and the water washing treatment in addition to the neutralization treatment and the water washing treatment. The treatment including the neutralization treatment and the water washing treatment may be, for example, a treatment including a neutralization treatment, a water washing treatment, and an organic solvent fraction cutting treatment (such as a toluene fraction cutting treatment, etc.).

[0170] The method for producing a (meth)acrylate according to an embodiment of the present invention preferably includes: before bringing the liquid L containing an esterified product of an esterification catalyst obtained in the production of a (meth)acrylate into contact with water in a reactor and / or a retention tank at a temperature T of 50°C or higher and 105°C or lower, subjecting a reaction mixture containing an esterified product of a (meth)acrylate and an esterification catalyst or a liquid obtained via the reaction mixture to an organic solvent fraction cutting treatment (such as a toluene fraction cutting treatment, etc.) to obtain the liquid L.

[0171] The method for producing a (meth)acrylate according to an embodiment of the present invention particularly preferably satisfies the following (A), the following (B), and the following (C):

[0172] (A) The contact between the liquid L in the reactor and / or the retention tank and water includes: when setting a temperature in the range of 95°C or higher and 105°C or lower as a set temperature, bringing the liquid L into contact with water in a state where the temperature T is maintained within the range of ±5°C of the set temperature for a holding time of 3 hours or longer and 10 hours or shorter;

[0173] (B) In the reactor and / or the retention tank, the proportion of the mass of water relative to the total mass of the liquid L and water in contact is 20% by mass or higher and 60% by mass or lower;

[0174] (C) The method for producing the (meth)acrylate includes: before contacting liquid L with water in a reactor and / or a retention tank at a temperature T, obtaining liquid L by subjecting a reaction mixture or a liquid obtained via the reaction mixture to an organic solvent fractionation treatment (such as toluene fractionation treatment, etc.), the reaction mixture containing an esterified product of a (meth)acrylate and an esterification catalyst.

[0175] In the above (B), the proportion of the mass of water relative to the total mass of liquid L and water is preferably 25% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and still more preferably 40% by mass or more and 60% by mass. In the above (B), the proportion of the mass of water relative to the total mass of liquid L and water can be 30% by mass or more and 40% by mass or less.

[0176] According to the method for producing the (meth)acrylate of the present invention, the (meth)acrylate can be produced in a high yield.

[0177] The (meth)acrylate obtained by the method for producing the (meth)acrylate of the present invention can be used, for example, as a raw material for vibration damping materials, printing toners, ink liquids, coatings, adhesives, binders, firing binders, synthetic resins, coating agents, dispersants, fiber treatment agents, etc., but the use of the (meth)acrylate is not limited thereto.

[0178] The embodiments of the present invention have been described in detail, but it is obvious that this is only illustrative and exemplary, not restrictive, and the scope of the present invention should be interpreted by the appended claims.

[0179] The present invention includes the following aspects and modes:

[0180] 1. A method for producing a (meth)acrylate, the production method including:

[0181] reacting (meth)acrylic acid with a secondary alcohol in a reactor in the presence of an acid-type esterification catalyst and a polymerization inhibitor; and

[0182] in the reactor and / or the retention tank, contacting liquid L containing the esterified product of the esterification catalyst obtained in the production of the (meth)acrylate with water at a temperature T of 50°C or more and 105°C or less;

[0183] 2. The production method according to 1. above, wherein the contact between liquid L and water in the reactor and / or the retention tank includes: when setting a temperature within the range of 55°C or more and 100°C or less as a set temperature, contacting liquid L with water in a state where the temperature T is maintained within the range of the set temperature ±5°C for a holding time of 0.5 hours or more and 100 hours or less;

[0184] 3. The manufacturing method according to 1. or 2. above, wherein the temperature T exceeds 80°C and is 105°C or lower; 4. The manufacturing method according to any one of 1. to 3. above, wherein the proportion of the mass of the water relative to the total mass of the liquid L and the water is 10% by mass or more;

[0185] 5. The manufacturing method according to any one of 1. to 4. above, wherein the manufacturing method includes: separating a mixture containing the liquid L and the water into an organic phase containing the (meth)acrylate and an aqueous phase containing the esterification catalyst by contacting the liquid L and the water in the reactor and / or the retention tank, and removing a part or all of the aqueous phase;

[0186] 6. The manufacturing method according to any one of 1. to 5. above, wherein the contact between the liquid L and the water in the reactor and / or the retention tank includes: using a liquid obtained by subjecting the following reaction mixture to neutralization treatment and water washing treatment as the liquid L, and contacting the liquid (i.e., the liquid obtained by the neutralization treatment and water washing treatment) with the water at the temperature T, the reaction mixture containing the (meth)acrylate and the esterified product;

[0187] 7. The manufacturing method according to any one of 1. to 5. above, wherein the contact between the liquid L and the water in the reactor and / or the retention tank includes: using a liquid obtained by subjecting the following reaction mixture to neutralization treatment and water washing treatment as the liquid L, and contacting the liquid (i.e., the liquid obtained by the neutralization treatment and water washing treatment) with the water at the temperature T, the reaction mixture containing the (meth)acrylate and the esterified product; the manufacturing method further includes: supplying the reaction mixture obtained after the treatment including the contact to a distillation column for distillation;

[0188] 8. The manufacturing method according to any one of 1. to 5. above, wherein the manufacturing method further includes:

[0189] subjecting the following reaction mixture to a treatment including neutralization treatment and water washing treatment, the reaction mixture containing the (meth)acrylate and the esterified product; and

[0190] distilling the reaction mixture obtained after the treatment including the neutralization treatment and the water washing treatment;

[0191] The contact of the liquid L in the reactor and / or the retention tank with the water includes: using the distilled liquid as the liquid L and contacting the distilled liquid with the water in the retention tank at the temperature T;

[0192] 9. The production method according to any one of 1. to 5. above, wherein the production method further includes:

[0193] subjecting a reaction mixture containing the (meth)acrylate and the esterified product to a treatment including a neutralization treatment and a water washing treatment;

[0194] feeding the reaction mixture obtained after the treatment including the neutralization treatment and the water washing treatment to a distillation column for distillation; and

[0195] withdrawing the bottom liquid of the distillation column from the bottom of the distillation column;

[0196] The contact of the liquid L in the reactor and / or the retention tank with the water includes: using the bottom liquid as the liquid L and contacting the bottom liquid with the water in the retention tank at the temperature T;

[0197] 10. The production method according to any one of 1. to 9. above, wherein the secondary alcohol is 2-octanol.

[0198] 11. The production method according to any one of 1. to 10. above, wherein the acid-type esterification catalyst is an acid-type esterification catalyst containing sulfur.

[0199] 12. The production method according to any one of 1. to 11. above, wherein the purity of the (meth)acrylate is 99.9% by mass or more.

[0200] Examples

[0201] The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. It should be noted that in the following examples, unless otherwise specified, the operations are carried out at room temperature (25 ± 5°C). In addition, unless otherwise specified, "%" and "parts" respectively refer to "% by mass" and "parts by mass".

[0202] (Example 1-1)

[0203] [Reaction step]

[0204] Into a 5 L glass round-bottom flask equipped with a stirrer, 1200 g of acrylic acid, 2385 g of 2-octanol (1.1 moles relative to 1 mole of acrylic acid), 400 g of toluene, 40 g of a 70 mass% aqueous methanesulfonic acid solution, and 6 g of phenothiazine were charged. Then, the round-bottom flask was immersed in an oil bath and the liquid in the round-bottom flask was heated.

[0205] Starting from the time point when the liquid temperature in the round-bottom flask reached 110 °C, after maintaining for 8 hours, the round-bottom flask was taken out of the oil bath. Then, the liquid was cooled to end the esterification reaction. By this operation, a reaction mixture was obtained. It should be noted that the pressure in the round-bottom flask was slowly reduced from 800 hPa to 180 hPa to keep the liquid temperature in the round-bottom flask at 110 °C.

[0206] After the reaction ended, the reaction mixture in the round-bottom flask was analyzed by gas chromatography (GC). As a result, it was confirmed that in addition to the formation of 1-methylheptyl acrylate as the reaction product (target substance), an esterified product (sulfonate) of the esterification catalyst was also formed.

[0207] [Neutralization process and water washing process]

[0208] Next, after cooling the reaction mixture obtained in the reaction process to 40 °C, 3756 g of the reaction mixture obtained in the reaction process and 1000 g of a 5 mass% aqueous sodium hydroxide solution were charged into a 5 L separatory funnel and stirred for 5 minutes. Then, the resulting mixture was allowed to stand for oil-water separation, and only the aqueous phase part was drawn out from the separatory funnel.

[0209] Then, 1000 g of water was additionally added to the separatory funnel and stirred for 5 minutes. Then, the resulting mixture was allowed to stand for oil-water separation, and only the aqueous phase part was taken out from the separatory funnel.

[0210] Through the above operations, a liquid (oil phase part) was obtained after the neutralization process and the water washing process. The obtained liquid (oil phase part) was used for the next process (toluene fraction cutting process).

[0211] It should be noted that in the neutralization process and the water washing process, the liquid temperature of the mixture containing water was 40 °C or lower.

[0212] [Toluene fraction cutting process]

[0213] Next, 900 g of the liquid (oil phase part) obtained after the neutralization process and the water washing process was charged into a 1 L round-bottom flask, immersed in an oil bath at 130 °C, and the liquid in the round-bottom flask was heated for simple distillation. It should be noted that the pressure in the round-bottom flask was slowly reduced from 680 hPa to 90 hPa. In addition, the distillate rate in this simple distillation was 15 mass%.

[0214] [Warm water treatment process]

[0215] Next, 680 g of the liquid (oil phase portion) obtained after the toluene fractionation step and 120 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer, and the flask was immersed in an oil bath to heat the liquid inside the round-bottom flask.

[0216] The temperature of the oil bath was adjusted so that the set temperature was 100°C. Starting from the time point when the temperature of the reaction mixture (the liquid obtained after the toluene fractionation step) and water inside the round-bottom flask reached 95°C, the temperature of the mixture was maintained within the range of 95°C or higher and 105°C or lower for 5 hours, and then the round-bottom flask was taken out of the oil bath and cooled.

[0217] After cooling, the liquid inside the round-bottom flask was transferred to a separatory funnel, allowed to stand for oil-water separation, and only the oil phase portion was taken out from the separatory funnel.

[0218] Through the above operations, a liquid (oil phase portion) was obtained after the warm water treatment process.

[0219] (Example 1-2)

[0220] In the warm water treatment process, the temperature of the oil bath was changed so that the set temperature was 90°C. Starting from the time point when the temperature of the reaction mixture and water inside the round-bottom flask reached 85°C, the temperature of the mixture was maintained within the range of 85°C or higher and 95°C or lower for 21 hours. Otherwise, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment process.

[0221] (Example 1-3)

[0222] In the warm water treatment process, the temperature of the oil bath was changed so that the set temperature was 80°C. Starting from the time point when the temperature of the reaction mixture and water inside the round-bottom flask reached 75°C, the temperature of the mixture was maintained within the range of 75°C or higher and 85°C or lower for 33 hours. Otherwise, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment process.

[0223] (Example 1-4)

[0224] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 70°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 65°C, the temperature of this mixture was maintained such that the time within the range of 65°C or higher and 75°C or lower was 43 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0225] (Example 1-5)

[0226] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 60°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 55°C, the temperature of this mixture was maintained such that the time within the range of 55°C or higher and 65°C or lower was 62 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0227] (Example 1-6)

[0228] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 50°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 45°C, the temperature of this mixture was maintained such that the time within the range of 45°C or higher and 55°C or lower was 89 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step. It should be noted that in Example 1-6, in the warm water treatment step, when the set temperature was 50°C and the temperature of the reaction mixture and water mixture was being maintained, there was a time when the temperature was within the range of 50°C or higher and 55°C or lower.

[0229] (Example 1-7)

[0230] In the warm water treatment step, 720 g of the liquid (oil phase portion) obtained after the toluene fractionation step and 80 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0231] (Example 1-8)

[0232] In the warm water treatment step, 640 g of the liquid (oil phase portion) obtained after the toluene fractionation step and 160 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0233] (Example 1-9)

[0234] In the warm water treatment step, 480 g of the liquid (oil phase portion) obtained after the toluene fractionation step and 320 g of water were charged into a 1 L glass round-bottom flask equipped with a stirrer. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0235] (Example 1-10)

[0236] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 90°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 85°C, the temperature of this mixture was maintained such that the time within the range of 85°C or higher and 95°C or lower was 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0237] (Example 1-11)

[0238] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 80°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 75°C, the temperature of this mixture was maintained such that the time within the range of 75°C or higher and 85°C or lower was 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0239] (Example 1-12)

[0240] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 70°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 65°C, the temperature of this mixture was maintained such that the time within the range of 65°C or higher and 75°C or lower was 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0241] (Example 1-13)

[0242] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 60°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 55°C, the temperature of this mixture was maintained such that the time within the range of 55°C or higher and 65°C or lower was 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0243] (Example 1-14)

[0244] In the warm water treatment step, change the temperature of the oil bath so that the set temperature is 50°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 45°C, maintain the temperature of this mixture so that the time within the range of 45°C or higher and 55°C or lower is 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase part) is obtained after the warm water treatment step. It should be noted that in Example 1-14, in the warm water treatment step, the set temperature was set to 50°C, and when maintaining the temperature of the mixture of the reaction mixture and water, there was a time when the temperature became within the range of 50°C or higher and 55°C or lower.

[0245] (Example 1-15)

[0246] In the warm water treatment step, set the set temperature to 100°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 95°C, maintain the temperature of this mixture so that the time within the range of 95°C or higher and 105°C or lower is 0.1 hour. Other than this, in the same manner as in Example 1-1, a liquid (oil phase part) is obtained after the warm water treatment step.

[0247] (Comparative Example 1-1)

[0248] Do not perform the warm water treatment step. Other than this, in the same manner as in Example 1-1, a liquid (oil phase part) is obtained after the toluene fraction cutting step.

[0249] (Comparative Example 1-2)

[0250] In the warm water treatment step, change the temperature of the oil bath so that the set temperature is 40°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 35°C, maintain the temperature of this mixture so that the time within the range of 35°C or higher and 45°C or lower is 5 hours. Other than this, in the same manner as in Example 1-1, a liquid (oil phase part) is obtained after the warm water treatment step. It should be noted that in the warm water treatment step of Comparative Example 1-2, the temperature of the mixture of the reaction mixture and water does not exceed 45°C.

[0251] (Comparative Example 1-3)

[0252] In the warm water treatment step, the set temperature was set to 100 °C. Only 800 g of the liquid (oil phase portion) obtained after the toluene fraction cut-off step was charged into a 1 L glass round-bottom flask equipped with a stirrer. Starting from the time point when the temperature of the reaction mixture in the round-bottom flask reached 95 °C, the temperature of the mixture was maintained, and the time within the range of 95 °C or higher and 105 °C or lower was 5 hours. Other than that, in the same manner as in Example 1-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0253] (Example 2-1)

[0254] [Reaction step]

[0255] 1200 g of methacrylic acid, 2000 g of 2-octanol (1.1 moles relative to 1 mole of methacrylic acid), 400 g of toluene, 80 g of a 70 mass% aqueous methanesulfonic acid solution, and 6 g of phenothiazine were charged into a 5 L glass round-bottom flask equipped with a stirrer. Then, the round-bottom flask was immersed in an oil bath, and the liquid in the round-bottom flask was heated.

[0256] Starting from the time point when the liquid temperature in the round-bottom flask reached 120 °C, after maintaining for 9 hours, the round-bottom flask was taken out of the oil bath. Then, the liquid was cooled to end the esterification reaction. By this operation, a reaction mixture was obtained. It should be noted that the pressure in the round-bottom flask was slowly reduced from 850 hPa to 330 hPa to keep the liquid temperature in the round-bottom flask at 120 °C.

[0257] After the reaction ended, the reaction mixture in the round-bottom flask was analyzed by gas chromatography (GC). As a result, it was confirmed that in addition to the formation of 1-methylheptyl methacrylate as the reaction product (target substance), an esterified product (sulfonate) of the esterification catalyst was also formed.

[0258] [Neutralization step and water washing step]

[0259] Next, after cooling the reaction mixture obtained in the reaction step to 40 °C, 3500 g of the reaction mixture obtained in the reaction step and 1000 g of a 5 mass% aqueous sodium hydroxide solution were charged into a 5 L separatory funnel and stirred for 5 minutes. Then, the obtained mixture was allowed to stand for oil-water separation, and only the aqueous phase portion was drawn out from the separatory funnel.

[0260] Then, 1000 g of water was additionally added to the separatory funnel and stirred for 5 minutes. Then, the obtained mixture was allowed to stand for oil-water separation, and only the aqueous phase portion was taken out from the separatory funnel.

[0261] Through the above operations, a liquid (oil phase portion) is obtained after the neutralization process and the water washing process. The obtained liquid (oil phase portion) is used in the next process (toluene fraction cutting process).

[0262] It should be noted that in the neutralization process and the water washing process, the liquid temperature of the mixture containing water is 40°C or lower.

[0263] [Toluene fraction cutting process]

[0264] Next, after loading 900 g of the liquid (oil phase portion) obtained after the neutralization process and the water washing process into a 1-L round-bottom flask, it is immersed in an oil bath at 130°C, and the liquid in the round-bottom flask is heated for simple distillation. It should be noted that the pressure in the round-bottom flask is slowly reduced from 680 hPa to 90 hPa. In addition, the distillate rate in this simple distillation is 20% by mass.

[0265] [Warm water treatment process]

[0266] Next, after loading 680 g of the liquid (oil phase portion) obtained after the toluene fraction cutting process and 120 g of water into a 1-L glass round-bottom flask equipped with a stirrer, it is immersed in an oil bath, and the liquid in the round-bottom flask is heated.

[0267] The temperature of the oil bath is adjusted so that the set temperature is 100°C. Starting from the time point when the temperature of the reaction mixture (the liquid obtained after the toluene fraction cutting process) and water in the round-bottom flask reaches 95°C, the temperature of this mixture is maintained so that the time within the range of 95°C or higher and 105°C or lower is 5 hours, and then the round-bottom flask is taken out of the oil bath and cooled.

[0268] After cooling, the liquid in the round-bottom flask is transferred to a separatory funnel, allowed to stand for oil-water separation, and only the oil phase portion is taken out from the separatory funnel.

[0269] Through the above operations, a liquid (oil phase portion) is obtained after the warm water treatment process.

[0270] (Example 2-2)

[0271] In the warm water treatment process, the temperature of the oil bath is changed so that the set temperature is 90°C. Starting from the time point when the temperature of the reaction mixture and water in the round-bottom flask reaches 85°C, the temperature of this mixture is maintained so that the time within the range of 85°C or higher and 95°C or lower is 21 hours. Except for this, in the same manner as in Example 2-1, a liquid (oil phase portion) is obtained after the warm water treatment process.

[0272] (Example 2-3)

[0273] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 80°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 75°C, the temperature of this mixture was maintained such that the time within the range of 75°C or higher and 85°C or lower was 33 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0274] (Example 2-4)

[0275] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 70°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 65°C, the temperature of this mixture was maintained such that the time within the range of 65°C or higher and 75°C or lower was 43 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0276] (Example 2-5)

[0277] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 60°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 55°C, the temperature of this mixture was maintained such that the time within the range of 55°C or higher and 65°C or lower was 62 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0278] (Example 2-6)

[0279] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 50°C. Starting from the time point when the temperature of the reaction mixture and water mixture in the round-bottom flask reached 45°C, the temperature of this mixture was maintained such that the time within the range of 45°C or higher and 55°C or lower was 89 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step. It should be noted that in Example 2-6, in the warm water treatment step, when the set temperature was 50°C and the temperature of the reaction mixture and water mixture was being maintained, there was a time when the temperature was within the range of 50°C or higher and 55°C or lower.

[0280] (Example 2-7)

[0281] In the warm water treatment step, 680 g of the liquid (oil phase portion) obtained after the neutralization step and the water washing step and 120 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer. The toluene fraction cutting step was carried out after the warm water treatment step instead of before it. Otherwise, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0282] (Example 2-8)

[0283] In the warm water treatment step, 560 g of the liquid (oil phase portion) obtained after the toluene fraction cutting step and 240 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer. Otherwise, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0284] (Example 2-9)

[0285] In the warm water treatment step, 480 g of the liquid (oil phase portion) obtained after the toluene fraction cutting step and 320 g of water were charged into a 1-L glass round-bottom flask equipped with a stirrer. Otherwise, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0286] (Example 2-10)

[0287] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 90°C. Starting from the time point when the temperature of the reaction mixture and water in the round-bottom flask reached 85°C, the temperature of the mixture was maintained such that the time within the range of 85°C or higher and 95°C or lower was 5 hours. Otherwise, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0288] (Example 2-11)

[0289] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 80°C. Starting from the time point when the temperature of the reaction mixture and water in the round-bottom flask reached 75°C, the temperature of the mixture was maintained such that the time within the range of 75°C or higher and 85°C or lower was 5 hours. Otherwise, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step.

[0290] (Example 2-12)

[0291] In the warm water treatment step, change the temperature of the oil bath so that the set temperature is 70°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 65°C, maintain the temperature of this mixture so that the time within the range of 65°C or higher and 75°C or lower is 5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase part) is obtained after the warm water treatment step.

[0292] (Example 2-13)

[0293] In the warm water treatment step, change the temperature of the oil bath so that the set temperature is 60°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 55°C, maintain the temperature of this mixture so that the time within the range of 55°C or higher and 65°C or lower is 5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase part) is obtained after the warm water treatment step.

[0294] (Example 2-14)

[0295] In the warm water treatment step, change the temperature of the oil bath so that the set temperature is 50°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 45°C, maintain the temperature of this mixture so that the time within the range of 45°C or higher and 55°C or lower is 5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase part) is obtained after the warm water treatment step. It should be noted that in Example 2-14, in the warm water treatment step, when the set temperature is 50°C and the temperature of the mixture of the reaction mixture and water is maintained, there is a time when the temperature is within the range of 50°C or higher and 55°C or lower.

[0296] (Example 2-15)

[0297] In the warm water treatment step, set the set temperature to 100°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reaches 95°C, maintain the temperature of this mixture so that the time within the range of 95°C or higher and 105°C or lower is 0.1 hour. Other than this, in the same manner as in Example 2-1, a liquid (oil phase part) is obtained after the warm water treatment step.

[0298] (Example 2-16)

[0299] In the warm water treatment step, the set temperature was set to 100°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reached 95°C, the temperature of this mixture was maintained such that the time within the range of 95°C or higher and 105°C or lower was 0.5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step was completed.

[0300] (Comparative Example 2-1)

[0301] The warm water treatment step was not carried out. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the toluene fraction cutting step was completed.

[0302] (Comparative Example 2-2)

[0303] In the warm water treatment step, the temperature of the oil bath was changed so that the set temperature was 40°C. Starting from the time point when the temperature of the mixture of the reaction mixture and water in the round-bottom flask reached 35°C, the temperature of this mixture was maintained such that the time within the range of 35°C or higher and 45°C or lower was 5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step was completed. It should be noted that in the warm water treatment step of Comparative Example 2-2, the temperature of the mixture of the reaction mixture and water did not exceed 45°C.

[0304] (Comparative Example 2-3)

[0305] In the warm water treatment step, the set temperature was set to 100°C. Only 800 g of the liquid (oil phase portion) obtained after the toluene fraction cutting step was charged into a 1-L glass round-bottom flask equipped with a stirrer. Starting from the time point when the temperature of the reaction mixture in the round-bottom flask was 95°C, the temperature of this mixture was maintained such that the time within the range of 95°C or higher and 105°C or lower was 5 hours. Other than this, in the same manner as in Example 2-1, a liquid (oil phase portion) was obtained after the warm water treatment step was completed.

[0306] (Evaluation)

[0307] For the liquid (oil phase portion) obtained after the warm water treatment step of the example, the liquid (oil phase portion) obtained after the toluene fraction cutting step of the comparative example, and the liquid (oil phase portion) obtained after the warm water treatment step of the comparative example, 2-octanol was quantitatively analyzed according to the following method.

[0308] [Quantitative Analysis of 2-Octanol (Pretreatment)]

[0309] (Concentration)

[0310] 100 g of the liquid (oil phase portion) obtained after the warm water treatment step of the example was charged into a round bottom flask, and simple distillation was carried out at an operating pressure of 68 hPa. The simple distillation was stopped at the time point when the distillate amount reached 75 g.

[0311] Similarly, 100 g of the liquid (oil phase portion) obtained in the comparative example was charged into a round bottom flask, and simple distillation was carried out at an operating pressure of 68 hPa. The simple distillation was stopped at the time point when the distillate amount reached 75 g.

[0312] (Thermal aging)

[0313] 25 g of the liquid remaining in the round bottom flask after concentration was thermally aged at 135 °C for 6 hours. For the liquid after this thermal aging, 2-octanol was quantitatively analyzed by the following method.

[0314] [Quantitative analysis of 2-octanol]

[0315] The concentration (mass %) of 2-octanol in the liquid was quantitatively analyzed by using gas chromatography (GC), and the concentration of 2-octanol was measured. It should be noted that the conditions for this quantitative analysis are as follows.

[0316] Gas chromatography: GC-2014 manufactured by Shimadzu Corporation.

[0317] Column: DB-1 manufactured by Agilent Technologies, Inc. (column length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm).

[0318] Column temperature: 70 °C.

[0319] Carrier gas: He.

[0320] The results obtained were shown as the "secondary alcohol concentration after thermal aging" in Tables 1 to 4. In this evaluation, a small value of the "secondary alcohol concentration after thermal aging" indicates a high yield of (meth)acrylate.

[0321] [Table 1]

[0322]

[0323] [Table 2]

[0324]

[0325] [Table 3]

[0326]

[0327] [Table 4]

[0328]

[0329] (Example 3-1)

[0330] For the liquid (oil phase portion) obtained after the warm water treatment step of Example 1-1, purification was carried out according to the following method to obtain 1-methylheptyl acrylate with a purity of 99.94% by mass.

[0331] The liquid (oil phase portion) obtained after the warm water treatment step was fed from the top of the low-boiling substance separation column. This low-boiling substance separation column is an Oldershaw type distillation column with 20 theoretical plates. While controlling the operating pressure to 20 - 30 hPa and the reflux ratio to 10 - 20 so that the distillate rate is 5 - 15% by mass, low-boiling substances were removed. Next, the bottom liquid of the low-boiling substance separation column was fed from the bottom of the high-boiling substance separation column. This high-boiling substance separation column is an Oldershaw type distillation column with 20 theoretical plates. While controlling the operating pressure to 20 - 30 hPa and the reflux ratio to 0.1 - 0.5 so that the distillate rate is 65 - 75% by mass, high-boiling substances were removed. Through the above operations, 1-methylheptyl acrylate (3-1) with a purity of 99.94% by mass was obtained.

[0332] (Comparative Example 3-1)

[0333] In Example 3-1, the liquid (oil phase portion) obtained in Example 1-1 was changed to the liquid (oil phase portion) obtained in Comparative Example 1-1, and other than that, the same operations as in Example 3-1 were carried out to obtain 1-methylheptyl acrylate (C3-1) with a purity of 99.34% by mass.

[0334] (Evaluation)

[0335] For the 1-methylheptyl acrylate obtained in Example 3-1 and Comparative Example 3-1, the flash point and purity were determined according to the following method.

[0336] (Flash Point)

[0337] The flash point of 1-methylheptyl acrylate was determined by the Cleveland open cup method.

[0338] (Purity)

[0339] The purity of 1-methylheptyl acrylate was calculated by the following formula. It should be noted that by using gas chromatography (GC) for quantitative analysis of 2-octene in 1-methylheptyl acrylate and 2-octanol in 1-methylheptyl acrylate, their contents (mass ppm) were determined. In addition, the acid component in 1-methylheptyl acrylate was determined by neutralization titration based on 0.1N-NaOH (quantified as acrylic acid) to determine its content (mass ppm).

[0340] [Formula 2]

[0341] Purity (mass %) of 1-methylheptyl acrylate = 100 - (total content (mass %) of 2-octene, 2-octanol, and acid components in 1-methylheptyl acrylate)

[0342] The evaluation results of the flash point of 1-methylheptyl acrylate and the purity of 1-methylheptyl acrylate are shown in Table 5. In Table 5, the flash point of 1-methylheptyl acrylate is recorded as "Flash Point", and the purity of 1-methylheptyl acrylate is recorded as "Purity".

[0343] [Table 5]

[0344] (Table 5) Flash Point and Purity of 1-Methylheptyl Acrylate

[0345]

[0346] By comparing each example and each comparative example in Tables 1 to 4, the method for manufacturing (meth)acrylate includes the following operation, which can reduce the concentration (mass %) of secondary alcohol after heat aging: in a reactor and / or a retention tank, the liquid L containing the esterified product of the esterification catalyst obtained in the manufacture of (meth)acrylate is contacted with water at a temperature T of 50°C or higher and 105°C or lower. This indicates that the yield of (meth)acrylate is significantly increased.

[0347] Furthermore, if the temperature T is a higher temperature, the concentration (mass %) of secondary alcohol after heat aging is further reduced. From this, it can be confirmed that (meth)acrylate is manufactured in a shorter time with a high yield.

[0348] Moreover, by controlling the mass of water relative to the total mass of liquid L and water, the concentration (mass %) of secondary alcohol after heat aging is further reduced. From this, it can be confirmed that (meth)acrylate is manufactured with a higher yield.

[0349] By comparing Example 3-1 and Comparative Example 3-1 in Table 5, it is confirmed that the method for manufacturing (meth)acrylate includes the following operation, which can improve the purity of (meth)acrylate: in a reactor and / or a retention tank, the liquid L containing the esterified product of the esterification catalyst obtained in the manufacture of (meth)acrylate is contacted with water at a temperature T of 50°C or higher and 105°C or lower.

[0350] By comparing Example 3-1 and Comparative Example 3-1 in Table 5, it was confirmed that the flash point of 1-methylheptyl acrylate in Example 3-1 after the warm water treatment step was higher than that of 1-methylheptyl acrylate in Comparative Example 3-1 without warm water treatment. It is considered that the reason is that when manufacturing (meth)acrylate through the following warm water treatment step, low-boiling substances (such as (meth)acrylic acid, secondary alcohol as raw materials, olefins as by-products, or combinations thereof) are reduced, thereby obtaining a high-purity (meth)acrylate. The warm water treatment step includes: bringing the liquid L containing the esterified product of the acid-type esterification catalyst obtained in the manufacture of (meth)acrylate into contact with water.

[0351] In addition, in this example, a glass round-bottom flask equipped with a stirrer was used to manufacture (meth)acrylate, but it is speculated that the effects of the present invention can also be obtained when the present invention is applied to a (meth)acrylate manufacturing process as Figures 1 to 6 shown.

[0352] This application is based on Japanese Patent Application No. 2022-185007 filed on November 18, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0353] Symbol Explanation

[0354] 1: Reactor;

[0355] 2: First distillation column;

[0356] 3, 3': Retention tank;

[0357] 4: Second distillation column;

[0358] 5: Third distillation column;

[0359] 6: Processing device;

[0360] 7: Neutralization and water washing tank.

Claims

1. A method for manufacturing a (meth)acrylate, the manufacturing method comprising: In the presence of an acid-type esterification catalyst and a polymerization inhibitor, (meth)acrylic acid is reacted with a secondary alcohol in a reactor; and In the reactor and / or the retention tank, a liquid L containing an esterified product of the esterification catalyst obtained in the production of the (meth)acrylate is brought into contact with water at a temperature T of 50°C or higher and 105°C or lower.

2. The manufacturing method according to claim 1, wherein, The contact of the liquid L with the water in the reactor and / or the retention tank includes: when a temperature in the range of 55°C or higher and 100°C or lower is set as the set temperature, the liquid L is brought into contact with the water in a state where the temperature T is maintained within the range of the set temperature ±5°C for a holding time of 0.5 hour or longer and 100 hours or shorter.

3. The manufacturing method according to claim 1, wherein, The temperature T exceeds 80°C and is 105°C or lower.

4. The manufacturing method according to claim 1, wherein, The proportion of the mass of the water relative to the total mass of the liquid L and the water is 10% by mass or more.

5. The manufacturing method according to claim 1, wherein, The production method includes: by the contact of the liquid L with the water in the reactor and / or the retention tank, separating a mixture containing the liquid L and the water into an organic phase containing the (meth)acrylate and an aqueous phase containing the esterification catalyst, removing a part or all of the aqueous phase.

6. The manufacturing method according to claim 1, wherein, The contact of the liquid L with the water in the reactor and / or the retention tank includes: using, as the liquid L, a liquid obtained by subjecting a reaction mixture containing the (meth)acrylate and the esterified product to a neutralization treatment and a water washing treatment, and bringing the liquid into contact with the water at the temperature T. The production method further includes: supplying the reaction mixture obtained after the treatment including the contact to a distillation column for distillation.

7. The manufacturing method according to claim 1, wherein, The production method further includes: subjecting a reaction mixture containing the (meth)acrylate and the esterified product to a treatment including a neutralization treatment and a water washing treatment; supplying the reaction mixture obtained after the treatment including the neutralization treatment and the water washing treatment to a distillation column for distillation; and withdrawing the bottom liquid of the distillation column from the bottom of the distillation column; The contact of the liquid L with the water in the reactor and / or the retention tank includes: using the bottom liquid as the liquid L and bringing the bottom liquid into contact with the water in the retention tank at the temperature T.

8. The manufacturing method according to claim 1, wherein, The secondary alcohol is 2-octanol.

9. The manufacturing method according to claim 1, wherein, The purity of the (meth)acrylate is 99.9% by mass or more.

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