JP4894203B2 - Process for producing higher alcohol esters of acrylic acid and higher alcohol esters of methacrylic acid - Google Patents

Description

  The present invention relates to a method for producing a higher alcohol ester of acrylic acid or a higher alcohol ester of methacrylic acid by a transesterification reaction between methyl ester of acrylic acid or methyl ester of methacrylic acid and a higher alcohol. In particular, the present invention relates to a method for efficiently producing a higher alcohol ester of acrylic acid or a higher alcohol ester of methacrylic acid by reacting while selectively extracting methanol as a by-product out of the reaction system by a gas separation membrane. Here, the higher alcohol is an alcohol compound having 2 or more carbon atoms. The higher alcohol ester of acrylic acid or the higher ester of methacrylic acid is an ester compound of acrylic acid or methacrylic acid and an alcohol compound having 2 or more carbon atoms. These higher alcohol esters are useful compounds as raw materials for paints and adhesives.

A method for producing a higher alcohol ester of acrylic acid or a higher alcohol ester of methacrylic acid by a transesterification reaction between methyl ester of acrylic acid or methyl ester of methacrylic acid and a higher alcohol is known. Examples of the catalyst used in the transesterification reaction include acids such as sulfuric acid and paratoluenesulfonic acid (Patent Document 1), bases such as alkali metal and alkaline earth metal alcoholates, and titanium compounds such as titanium alcoholates (Patent Documents). 2), complexes of iron, zinc, barium and the like (Patent Documents 3-5) have been proposed.
The transesterification reaction using these catalysts is an equilibrium reaction and is performed by a batch-wise or continuous reactive distillation system. Conventionally, in these reactions, a method in which methanol produced as a by-product is extracted out of the reaction system and the reaction equilibrium is shifted to the production system side to allow efficient reaction is employed. However, in this method, since methanol and the raw material acrylic acid methyl ester or methacrylic acid methyl ester take an azeotropic composition, the raw material acrylic acid methyl ester or methacrylic acid methyl ester is also removed from the reaction system as an azeotrope with methanol. There was a problem that the methanol was extracted (distilled), and further, there was a problem that methanol could not be extracted out of the reaction system at a high concentration.
Patent Document 6 discloses a process for producing methacrolein or acrolein with alcohol and molecular oxygen in the presence of a Pd-containing catalyst to produce a methacrylic acid ester or an acrylic acid ester, from a mixture of alcohol and water. A production method is disclosed in which a reaction is carried out while removing water by a separation membrane capable of selectively permeating water. However, in this production method, it was water instead of alcohol that was selectively removed. Moreover, the separation method is a pervaporation method in which a mixed solution of alcohol and water is brought into direct contact with the membrane to selectively permeate water from the mixed solution.
Patent Document 7 describes an asymmetric hollow fiber separation membrane having improved solvent resistance to organic solvents and practical separation performance for organic vapors. However, there was no description about applying such an asymmetric hollow fiber separation membrane to a transesterification reaction between methyl acrylate or methyl methacrylate and a higher alcohol.

JP 62-42948 A JP-A-1-258642 JP-A-53-141213 JP 53-105417 A JP-A-53-144523 WO98 / 11050 publication JP 2004-267810 A

  The object of the present invention is to provide an improved process for producing higher alcohol esters of acrylic acid or higher alcohol esters of methacrylic acid from methyl acrylate or methyl methacrylate and higher alcohols.

  In the present invention, a methyl ester represented by the following chemical formula (1) and an alcohol having 2 or more carbon atoms are subjected to a transesterification reaction while selectively extracting methanol as a by-product using a gas separation membrane, and a higher class represented by the following chemical formula (2). The present invention relates to a method for producing a higher alcohol ester characterized by obtaining an alcohol ester.

（但し、式中、Ｒ^１は水素原子又はメチル基を表す。）

(In the formula, R ¹ represents a hydrogen atom or a methyl group.)

（但し、式中、Ｒ^１は水素原子又はメチル基を表し、Ｒ^２は炭素数が２以上のアルコールから水酸基を除いた残基を表す。）

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a residue obtained by removing a hydroxyl group from an alcohol having 2 or more carbon atoms.)

  Further, the present invention generates a mixed vapor containing methanol as a by-product and the methyl ester as a raw material from a reaction mixture obtained by reacting a methyl ester and an alcohol having 2 or more carbon atoms in the presence of a catalyst. The present invention relates to a method for producing a higher alcohol ester, wherein a mixed vapor is brought into contact with a gas separation membrane to selectively permeate and extract methanol, and a non-permeated methyl ester is returned to a reaction mixture.

Furthermore, the gas separation membrane suitably used in the present invention is a ratio of the permeation rate of methanol vapor at 120 ° C. to the permeation rate of raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor (P ′ _MeOH / P ′ _{MA or MMA).} ) Is 2 or more, methanol vapor permeation rate at 120 ° C. (P ′ _MeOH ) is 1 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg or more, and dissolved in parachlorophenol The non-symmetric asymmetric polyimide hollow fiber membrane.

  In the present invention, by-product methanol is selectively extracted out of the reaction system, and the raw material acrylic acid methyl ester or methacrylic acid methyl ester remains in the reaction system. For this reason, it is possible to obtain a higher alcohol ester of acrylic acid or a higher alcohol ester of methacrylic acid with high efficiency and high yield without additionally supplying the methyl ester as a raw material. Furthermore, since the purity of methanol extracted out of the reaction system is 70% by weight or more, preferably 80% by weight or more, it can be easily recovered and reused.

  The present invention is characterized in that a raw material methyl acrylate or methacrylic acid and a higher alcohol are reacted while methanol by-produced is selectively extracted out of the reaction system by a gas separation membrane. In the present invention, preferably, from the reaction mixture obtained by reacting raw material methyl acrylate or methacrylic acid methyl ester and higher alcohol in the presence of a catalyst, by-product methanol and raw material methyl acrylate or methacrylic acid A mixed vapor containing methyl ester is generated, and the mixed vapor is brought into contact with a gas separation membrane to selectively permeate methanol and withdrawn out of the reaction system. On the other hand, a non-permeated highly concentrated raw material methyl acrylate The ester or methacrylic acid methyl ester is condensed and returned to the reaction mixture.

  In the present invention, the higher alcohol is a monovalent or polyhydric alcohol compound having 2 or more carbon atoms, preferably 3 or more carbon atoms, more preferably a monovalent or polyhydric alcohol compound having 3 to 20 carbon atoms. Yes, for example, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol, cyclohexyl alcohol, ethylene glycol, triethylene glycol, tetraethylene glycol 1,3-butanediol, trimethylolpropane and the like can be preferably exemplified.

  In the present invention, as the catalyst, those already known for use in transesterification can be suitably used. For example, an acid such as sulfuric acid or paratoluenesulfonic acid, a base such as an alkali metal or alkaline earth metal alcoholate, a titanium compound such as titanium alcoholate, or a metal complex catalyst such as iron is used. At least one of these catalysts is a ratio of 0.00001 to 0.1 mol, preferably 0.00005 to 0.01 mol, more preferably 0.0001 to 0.05 mol, per mol of higher alcohol. Used in.

In the present invention, the raw material acrylic acid methyl ester or methacrylic acid methyl ester is not particularly limited, but is about 0.1 to 10 mol, preferably 0.5 to 5 mol, per 1 mol of higher alcohol. Usually, it is preferable to use an acrylic acid methyl ester or methacrylic acid methyl ester in an excess ratio of about 1 to 3 moles of raw material.
Compared with the present invention and the reactive distillation system, regarding the molar ratio of the raw material methyl acrylate or methacrylic acid ester to the higher alcohol, in the reactive distillation system, the raw material ester is extracted out of the reaction system during the reaction. Therefore, in order to suppress a decrease in yield, it is necessary to use the raw material ester in large excess in advance. However, in the present invention, since the raw material ester is not extracted out of the reaction system, the raw material ester is high even in a relatively small amount. Yields can be achieved.

  The transesterification reaction of the present invention deals with acrylic acid methyl ester or methacrylic acid methyl ester which is easily polymerized, and therefore it is preferable to carry out in the presence of a polymerization inhibitor. As the polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, di-t-butylcatechol, phenothiazine, p-phenylenediamine, methylenediamine and the like are preferably used.

  The reaction temperature of the transesterification reaction is 50 to 200 ° C, preferably 70 to 150 ° C, more preferably 80 to 130 ° C, and particularly preferably 85 to 120 ° C. The pressure during the reaction is preferably set in the range of 0.1 to 1 MPa corresponding to the reaction temperature, and the atmosphere during the reaction is preferably an inert gas atmosphere such as nitrogen. The reaction time (corresponding to the residence time when the reaction is carried out continuously) varies depending on the reaction temperature and the amount of catalyst, but is preferably in the range of 1 to 10 hours.

In the present invention, a mixed vapor containing by-product methanol and raw material acrylic acid methyl ester or methacrylic acid methyl ester is generated from the reaction mixture. When the boiling point of the higher alcohol used is low, the mixed steam may contain a higher alcohol, but the raw material higher alcohol may be contained in the mixed steam. In any case, it is not possible to generate only methanol vapor. And the said mixed vapor | steam will generate | occur | produce easily on the above-mentioned reaction conditions. This mixed vapor is brought into contact with the surface of the gas separation membrane. While the mixed vapor is in contact with the gas separation membrane, the methanol vapor selectively permeates the gas separation membrane and is extracted out of the reaction system due to the partial pressure difference between the methanol vapors on both sides of the gas separation membrane. Even if the raw material methyl acrylate or methyl methacrylate vapor contacts with the gas separation membrane, it does not easily permeate the gas separation membrane and remains on the non-permeation side of the gas separation membrane, that is, the reaction system side. In the present invention, the acrylic acid methyl ester or methacrylic acid methyl ester vapor remaining on the non-permeating side of the gas separation membrane is preferably cooled and condensed and returned to the reaction mixture.
In addition, when higher alcohol as a raw material is contained in the mixed vapor, the higher alcohol vapor does not easily pass through the gas separation membrane even if it comes into contact with the gas separation membrane, so the non-permeation side of the gas separation membrane, that is, the reaction system side Remain in. The higher alcohol vapor remaining on the non-permeating side of the gas separation membrane is also preferably cooled and condensed and returned to the reaction mixture.

In the present invention, in order to allow methanol vapor to selectively permeate from the mixed vapor by the gas separation membrane and efficiently extract it, the methanol vapor has high selective permeability to the raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor and methanol. It is preferable to use a gas separation membrane having a high vapor transmission rate and to increase the effective membrane area of the gas separation membrane.
In addition, the partial pressure of methanol vapor contacting the gas separation membrane can be increased by making the reaction system a pressurized system, or the permeation side of the gas separation membrane can be reduced to reduce the partial pressure difference between the methanol vapors on both sides of the gas separation membrane. In addition, a gas other than methanol (for example, air, nitrogen gas, etc.) is allowed to flow as a sweep gas to the permeation side of the gas separation membrane, and the permeated methanol vapor is forcibly swept from the permeation side of the gas separation membrane. In order to increase the separation efficiency, it is preferable to react using a reactor equipped with a distillation column, etc., and distill the mixed vapor to an azeotropic composition in the distillation column and then contact with the gas separation membrane. is there. Furthermore, in the present invention, before bringing the mixed vapor into contact with the gas separation membrane, it is preferable to superheat at about 2-3 ° C. or more, preferably 5 ° C. or more in order to maintain the separation efficiency of the gas separation membrane. .

  In the present invention, the transesterification reaction is carried out batchwise or continuously. When the production scale is large, a continuous reaction (a method in which methyl methacrylate or methacrylic acid ester, higher alcohol and catalyst are continuously supplied, methanol is continuously extracted, and the reaction solution is continuously extracted. Is particularly preferred.

  A solvent is not particularly required in the transesterification reaction, but there is no problem in using it as long as it is inert in the reaction system. When the solvent has a low boiling point and is vaporized together with methanol and contained in the mixed vapor, a solvent that is more difficult to permeate the gas separation membrane than the raw material methyl acrylate or methyl methacrylate vapor is preferable.

  The gas separation membrane used in the present invention is not particularly limited as long as it selectively permeates methanol vapor with respect to the raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor. For example, polymer films such as polyimide, polycarbonate, polysulfone, polyetherimide, polyamideimide, films obtained by heat-treating these polymer films, partially carbonized films or carbon films obtained by heat-treating polymer films, ceramics A film or the like can be preferably used. These films may be uniform films, asymmetric films, or composite films. Furthermore, the form of the membrane may be any of a hollow fiber membrane, a flat membrane, a spiral membrane and the like.

The gas separation membrane used in the present invention has a ratio (P ′ _MeOH / P ′ _{MA or MMA} ) between the permeation rate of methanol vapor at 120 ° C. and the permeation rate of raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor. In particular, those of 5 or more, more preferably 10 or more are suitable. That is, when methyl acrylate is used as a raw material, the ratio (P ′ _MeOH / P ′ _MA ) between the permeation rate of methanol vapor at 120 ° C. and the permeation rate of raw material methyl acrylate vapor is 2 or more, particularly 5 More preferably, 10 or more are preferable. When methyl methacrylate is used as the raw material, the ratio of the vapor transmission rate of methanol vapor to the vapor transmission rate of the raw material methyl methacrylate vapor at 120 ° C. (P ′ _MeOH / _P′MMA ) is preferably 2 or more, particularly 5 or more, and more preferably 10 or more.
When the ratio (P ′ _MeOH / P ′ _{MA or MMA} ) between the permeation rate of methanol vapor and the permeation rate of the raw material acrylic acid methyl ester or methacrylic acid ester vapor is less than 2, by-product methanol from the reaction system of the transesterification reaction When an attempt is made to extract the water, a considerable amount of the raw material, acrylic acid methyl ester or methacrylic acid methyl ester vapor, is also discharged out of the reaction system at the same time, making it difficult to obtain the effects of the present invention. The gas separation membrane used in the present invention has a larger ratio (P ′ _MeOH / P ′ _{MA or MMA} ) between the permeation rate of methanol vapor and the permeation rate of raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor. Although it is preferable, it is usually difficult to easily obtain more than 1000.

The gas separation membrane used in the present invention has a methanol vapor permeation rate ( _P′MeOH ) at 120 ° C. of 1 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg or more, particularly 5 × 10 ⁻⁵ cm. ³ (STP) / cm ² · sec · cmHg is preferred. The gas separation membrane used in the present invention is more suitable as the methanol vapor permeation rate (P ′ _MeOH ) increases. Usually, 1000 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg is used. It is difficult to easily get beyond.

  Furthermore, the gas separation membrane used in the present invention preferably has good solvent resistance against methanol, methyl acrylate or methyl methacrylate. If the solvent resistance of the gas separation membrane is low, the gas separation performance is lowered by an organic vapor such as methanol, acrylic acid methyl ester, or methacrylic acid methyl ester, and therefore, it cannot be suitably used. In the present invention, specifically, it is preferable to use a gas separation membrane having solvent resistance that does not dissolve even when immersed in parachlorophenol at 50 ° C. for 30 minutes. A gas separation membrane having a solvent resistance not less than that which does not dissolve in parachlorophenol does not deteriorate in gas separation performance even with an organic vapor such as methanol, acrylic acid methyl ester or methacrylic acid methyl ester.

  Below, the gas separation membrane which is not melt | dissolved in parachlorophenol which can be used conveniently by this invention is demonstrated. Such a gas separation membrane is not limited, for example, a method described in detail in Patent Document 7, that is, an asymmetric hollow fiber membrane is formed using polyimide having a substituent, and then the asymmetric It can be suitably obtained by heat treatment under such a temperature condition that the polyimide skeleton and the asymmetric structure of the hollow fiber membrane are retained and the substituents are decomposed / desorbed or cross-linked and become so-called infusible. (See paragraphs [0019] to [0026] of Patent Document 7) This heat treatment not only improves the solvent resistance, but also improves the separation performance such as the permeation rate and the permeation rate ratio for organic vapor. Furthermore, since the asymmetric structure is retained and the polyimide skeleton is retained to maintain the mechanical strength before the heat treatment, it is a practical gas separation membrane for separating and recovering organic vapor.

  The polyimide having the substituent used for forming this gas separation membrane is, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3,3 ′, 4 as a tetracarboxylic acid component. '-Biphenyltetracarboxylic acid, 2,2', 3,3'-biphenyltetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 1,4,5,8-naphthalenetetra Carboxylic acid and tetracarboxylic acid such as pyromellitic acid, dianhydride or esterified product thereof, and 1,3-diaminobenzene-4-sulfonic acid and triethylammonium salt thereof as diamine component, 1,3- Diaminobenzene-4,6-disulfonic acid and its triethylammonium salt, 3,5-diaminobenzoic acid, 2,5-dichloro-p Phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2-trifluoromethyl-p-phenylenediamine, benzidine-2,2′-disulfonic acid and its triethylammonium salt, 2,2 ′, 5,5′- Tetrachlorobenzidine, 3,3′-dihydroxybenzidine, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-di (trifluoromethyl) -4,4′-diaminodiphenyl, o-dianisidine 3,3′-dicarboxy-4,4′-diaminobiphenyl, 3,3 ′, 5,5′-tetrabromo-6,6′-dimethylbenzidine, 3,3′-dimethyl-4,4′-diamino Diphenylsulfone, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 2,2-bis (3-amino-4-methylpheny ) Hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2,8-dimethyl-3,7-diaminodibenzothiophene-5,5-dioxide, 4,4'-diamino It can be obtained by polymerization and imidization using a diamine having a substituent such as diphenyl ether-2,2′-disulfonic acid and its triethylammonium salt. (See paragraphs [0013] to [0017] of Patent Document 7)

  Further, the gas separation membrane that can be suitably used in the present invention is preferably a hollow fiber membrane because the effective membrane area can be easily increased, and an extremely thin skin layer (uniform layer) for further increasing the gas permeation rate. And an asymmetric membrane comprising a porous layer is preferred. Specifically, the thickness of the skin layer is preferably 10 to 200 nm, and the thickness of the porous layer is preferably 20 to 200 μm. If the thickness of the skin layer is less than 10 nm, it is difficult to produce, and if it exceeds 200 nm, the gas permeation rate decreases, which is not preferable. On the other hand, if the porous layer is less than 20 μm, the mechanical strength becomes small and impractical, and if it exceeds 200 μm, the permeation rate of the porous gas becomes small.

  The transesterification of the present invention will be described with reference to the schematic diagram of an example of the production apparatus of the present invention shown in FIG. Raw material methyl acrylate or methacrylic acid methyl ester, a higher alcohol, a catalyst, and a solvent as required are added to a reaction vessel 1 equipped with a heating means and a stirring means, and stirred while heating to a predetermined temperature. A mixed vapor containing methanol vapor by-produced from the reaction mixture and raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor is generated and superheated by the heating device 2 and introduced into the gas separation membrane device 3. In the gas separation device, the non-permeate side and the permeate side of the gas separation membrane are isolated, the non-permeate side communicates with the reaction system, and the non-permeate side communicates with the outside of the reaction system. Permeated methanol vapor can be extracted out of the reaction system. The permeation side of the gas separation membrane of the gas separation device 3 is decompressed by the vacuum pump 4. In the gas separation membrane device 3, the mixed vapor contacts the gas separation membrane, and methanol vapor selectively permeates the membrane. On the permeate side of the membrane, methanol vapor becomes highly concentrated and is condensed by the cooling device 5 and recovered in a recovery container 6 equipped with cooling means. The mixed vapor that flows on the non-permeate side of the membrane has a high concentration of raw material acrylic acid methyl ester or methacrylic acid methyl ester, and is condensed by the cooling device 7 and pumped through a buffer tank 8 having cooling means. Is returned to the reaction tank 1.

In the present invention, it is preferable to use an effective membrane area of the gas separation membrane of 30 cm ² or more, preferably 60 cm ² or more per mole of raw material acrylic acid methyl ester or methacrylic acid methyl ester. If the effective membrane area is smaller than the above range, the step of selectively extracting methanol with the separation membrane becomes the rate-determining rate of the transesterification reaction, making it difficult to sufficiently improve the reaction yield. When the effective membrane area is within the above range, for example, in the case of butyl methacrylate, butyl methacrylate can be easily obtained in a yield of 80 mol% or more, preferably 90 mol% or more based on alcohol.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

Abbreviations used in the following examples will be described.
s-BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 6FDA: 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride PMDA: pyromellitic dianhydride Product TSN: 2,8-dimethyl-3,7-diaminodibenzothiophene-5,5-dioxide TCB: 2,2 ′, 5,5′-tetrachlorobenzidine MeOH: methanol MA: acrylic acid methyl ester MMA: methacrylic acid Methyl ester

The measurement method used in the following examples will be described.
(Measurement of gas separation performance for mixed steam)
Preparation of measurement hollow fiber membrane element: 10 hollow fiber membranes are bundled and cut to form a hollow fiber membrane bundle, and one end of the yarn bundle is fixed with an epoxy resin so that the end of the hollow fiber is opened, The other end was fixed with an epoxy resin so that the end of the hollow fiber was closed, and a hollow fiber membrane element for measurement having an effective length of 7.5 cm and an effective membrane area of 9.4 cm ² was manufactured.
Measurement of gas separation performance: A description will be given with reference to a schematic diagram (FIG. 2) of a gas separation membrane performance measuring apparatus. In a flask 11 equipped with a heating device, the molar composition ratio of methanol and raw material acrylic acid methyl ester or methacrylic acid methyl ester to the generated mixed vapor of methanol and raw material acrylic acid methyl ester or methacrylic acid methyl ester is roughly The mixture is charged at a predetermined mixing ratio so as to have an azeotropic composition ratio (methanol: methyl acrylate = 5: 5, methanol: methyl methacrylate = 9: 1), and heated with a heating device to generate mixed organic vapor. I let you. This mixed organic vapor was superheated by a heating device 12 for superheating to be a mixed organic vapor having an atmospheric pressure of 120 ° C., cooled and liquefied by a cooling device 15, and circulated to the flask 11. During this time, the measuring hollow fiber membrane element is not incorporated in the measuring device. The built-in part is sealed. After the preparation of the mixed organic vapor was continued for 2 hours or more, the mixed organic vapor was analyzed to confirm that the molar composition ratio of methanol to the raw material acrylic acid methyl ester or methacrylic acid methyl ester was the azeotropic composition ratio. confirmed. Thereafter, the measurement hollow fiber membrane element 10 is incorporated into the gas separation membrane performance measuring apparatus as shown in FIG. 2, and the permeation side (inside) of the hollow fiber membrane of the element is maintained at a reduced pressure of 0.0007 MPa by the vacuum pump 13. Gas separation started. After continuing the gas separation for 30 minutes or more as a running-in operation, the permeated gas obtained from the permeation side of the measurement hollow fiber membrane element 10 was led to the dry ice-methanol trap 14 for 30 minutes and collected as a condensate. While calculating | requiring the weight of the collected condensate, the density | concentration of each component was measured by the gas chromatography analysis method, and the quantity of each component of the permeate | transmitted organic vapor | steam was calculated | required. From the obtained amount of each organic vapor component, the transmission rate and the transmission rate ratio of each organic vapor component were calculated. The amount of methanol and the raw material acrylic acid methyl ester or methacrylic acid methyl ester was set to a sufficient amount so that the mixing ratio was not substantially changed during the measurement.

(Measurement of solvent resistance)
After three hollow fiber membranes cut to a length of 2 cm were completely immersed in 20 ml of parachlorophenol adjusted to a temperature of 50 ° C. and held for 30 minutes, the hollow fiber membranes were taken out and visually observed. Observed. In the case of dissolution during immersion, “x” indicates that the hollow fiber membrane shape is maintained but swelling is observed, and “Δ” indicates that no change is observed.

[Reference Example 1]
A gas separation membrane was produced as follows.
(Preparation of polyimide solution having substituents)
0.0315 mol s-BPDA, 0.0280 mol 6FDA, 0.0105 mol PMDA, 0.0355 mol TSN, and 0.0355 mol TCB together with 215 g of parachlorophenol, heating device and agitator Weigh in a separable flask equipped with a nitrogen gas inlet tube and a discharge tube, conduct a polymerization imidization reaction at a temperature of 170 ° C. for 15 hours with stirring in a nitrogen gas atmosphere, and dissolve in parachlorophenol A polyimide solution having a substituent with a polyimide concentration of 17% by weight was prepared.

(Production of asymmetric hollow fiber membrane made of polyimide having substituents)
This solution was filtered through a 400 mesh stainless steel wire mesh to obtain a dope for spinning. This dope is charged into a spinning device equipped with a hollow fiber spinning nozzle (circular opening outer diameter: 1000 μm, circular opening slit width: 200 μm, core opening outer diameter: 400 μm), and hollow fiber spinning nozzle. The hollow fiber-shaped molded product is then discharged into a primary coagulation bath at a temperature of 0 ° C. composed of a 70 wt% aqueous ethanol solution, and a secondary coagulation bath (coagulation solution) provided with a pair of guide rolls. The solidification was completed by reciprocating between guide rolls in a 70 wt% ethanol aqueous solution (temperature: 0 ° C.), and the wet asymmetric hollow fiber membrane was wound around a bobbin. The take-up speed was 10 m / min. This asymmetric hollow fiber membrane was thoroughly washed in ethanol, and then the ethanol was replaced with isooctane. Then, isooctane was evaporated and dried at 100 ° C. to obtain an asymmetric hollow fiber membrane composed of a polyimide having a substituent.

(Production and performance of infusibilized asymmetric hollow fiber gas separation membrane)
The asymmetric hollow fiber membrane composed of the polyimide having the substituent is heat-treated in an air atmosphere oven at a temperature of 400 ° C. for 30 minutes to obtain an asymmetric gas separation membrane having an outer diameter of about 400 μm and an inner diameter of about 200 μm. Obtained. The obtained infusible asymmetric gas separation membrane has solvent resistance and gas separation membrane characteristics: solvent resistance is ○, methanol vapor permeation rate (P ′ _MeOH ) is 15 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg, the ratio of the permeation rate of methanol vapor and acrylic acid methyl ester vapor (P ′ _MeOH / P ′ _MA ) is 20, the ratio of the permeation rate of methanol vapor and methyl methacrylate vapor (P ′ _MeOH / _P′MMA ) was 150.

[Example 1]
A gas separation membrane device 3 composed of an infusible asymmetric hollow fiber gas separation membrane produced in Reference Example 1 and having an effective membrane area of 137 cm ² was incorporated into the reaction apparatus as shown in FIG. Here, 1 is a reaction tank that can be heated and stirred, 2 is a heating means for superheating, 4 is a vacuum pump, 5 is a cooling device for cooling and condensing and trapping the permeated methanol vapor, 6 A recovery container having a cooling means, 7 is a cooling device for cooling and condensing the mixed vapor after methanol vapor is selectively removed, and refluxing it to the flask, 8 is a buffer tank having the cooling means, and 9 is a liquid It is a pump. Reference numeral 3 denotes a gas separation membrane device, in which a hollow fiber inner space and a hollow fiber outer space of the hollow fiber gas separation membrane are separated with a hollow fiber separation membrane interposed therebetween, and the hollow fiber inner space is interposed via a cooling device 5. The hollow fiber outer space is connected to the reaction system so that the pressure is reduced by communicating with the vacuum pump 4, and the mixed steam generated in the reaction tank 1 is superheated by the heating means 2 and then the hollow fiber is separated. It is placed in contact with the outer surface of the membrane.

  A reactor 1 was charged with 1.0 mol of methacrylic acid methyl ester, 0.5 mol of ethanol, 0.00081 mol of p-methoxyphenol as a polymerization inhibitor, and 0.0015 mol of iron acetylacetonate as a catalyst while stirring. The temperature of the reaction mixture was raised to 100 ° C. The inside of the reaction tank 1 was an atmosphere of nitrogen gas at atmospheric pressure, and the permeation side of the gas separation membrane was decompressed to 0.0007 MPa by a vacuum pump. As the reaction progressed, the by-produced methanol vapor selectively permeated through the gas separation membrane, and was liquefied by the cooling device 5 and recovered in the recovery container 6 equipped with cooling means. The mixed vapor that flows on the non-permeate side of the separation membrane has a high concentration of methyl methacrylate and ethanol, and is condensed by the cooling device 7 and is reacted by the reaction tank 1 by the pump 9 through the buffer tank 8 provided with cooling means. Returned to. The reaction was completed 8 hours after the start of the reaction. In the recovery container 6 equipped with a cooling means during the reaction, a mixed liquid consisting of 71.9% by weight of methanol, 4.3% by weight of methyl methacrylate and 23.8% of ethanol was recovered by gas chromatography analysis. . When the reaction solution in the reaction layer 1 was analyzed by gas chromatography, the yield of methacrylic acid ethyl ester based on ethanol was 55.7 mol%.

[Comparative Example 1]
The reaction was carried out in the same manner as in Example 1 without extracting methanol vapor from the reaction system by the gas separation membrane. When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of ethyl methacrylate based on ethanol was 25.5 mol%.

[Example 2]
The same operation as in Example 1 was performed except that 0.5 mol of 1-butanol was used instead of 0.5 mol of ethanol and the reaction temperature was 110 ° C.
In the collection container 6 equipped with a cooling means during the reaction, a mixed solution consisting of 93.6% by weight of methanol and 6.4% by weight of methacrylic acid methyl ester was recovered.
When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 98.9 mol%.

[Comparative Example 2]
The reaction was carried out in the same manner as in Example 2 without extracting methanol vapor from the reaction system by the gas separation membrane. When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 60.7 mol%.

Example 3
The same operation as in Example 2 was performed except that 1.0 mol of methyl acrylate was used instead of 1.0 mol of methyl methacrylate and the reaction temperature was 95 ° C.
In a collection vessel 6 equipped with a cooling means during the reaction, a mixed solution consisting of 74.2% by weight of methanol and 25.8% by weight of acrylic acid methyl ester was collected.
When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of butyl acrylate based on 1-butanol was 80.8 mol%.

Example 4
The same operation as in Example 2 was performed except that the effective membrane area of the separation membrane was set to 70 cm ² .
In a collection container 6 equipped with a cooling means during the reaction, a mixed solution consisting of 89.3% by weight of methanol and 10.7% by weight of methacrylic acid methyl ester was collected.
When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 93.1 mol%.

Example 5
The same operation as in Example 2 was performed except that the effective membrane area of the separation membrane was 35 cm ² .
In a collection vessel 6 equipped with a cooling means during the reaction, a mixed solution consisting of 86.4% by weight of methanol and 13.6% by weight of methyl methacrylate was collected.
When the reaction solution after 8 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 82.6 mol%.

Example 6
The same operation as in Example 2 was performed except that the catalyst was 0.002 mol of tetrabutoxytitanium.
In a collection container 6 equipped with a cooling means during the reaction, a mixed solution consisting of 95.6% by weight of methanol and 4.4% by weight of methyl methacrylate was collected.
When the reaction solution after 6 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 94.7 mol%.

Example 7
The same operation as in Example 6 was performed except that the methyl methacrylate was charged to 0.8 mol in the reaction vessel.
In a collection container 6 equipped with a cooling means during the reaction, a mixed solution consisting of 95.6% by weight of methanol and 4.4% by weight of methyl methacrylate was collected.
When the reaction liquid after 6 hours was analyzed by gas chromatography, the yield of butyl methacrylate based on 1-butanol was 92.3 mol%, and the amount of methyl methacrylate was less charged than Example 6. However, the yield was hardly affected.

  The present invention is an improved method of producing acrylic acid or methacrylic acid higher ester from acrylic acid methyl ester or methacrylic acid methyl ester and higher alcohol, and obtains acrylic acid or methacrylic acid higher ester with high yield and high efficiency. Can do. Furthermore, the methanol extracted out of the reaction system has a high purity and can be easily recovered and reused.

The schematic diagram for demonstrating the outline of an example of the manufacturing apparatus used by this invention Schematic schematic diagram of an apparatus for measuring the gas separation performance of a gas separation membrane

Explanation of symbols

1: Reaction tank provided with heating means and stirring means 2: Heating means for superheating mixed steam 3: Gas separation membrane device 4: Vacuum pump 5: Cooling device 6: Recovery container 7 with cooling means: Cooling Apparatus 8: Buffer tank provided with cooling means 9: Liquid pump 10: Gas separation membrane apparatus 11: Heatable and stirred flask 12: Heating apparatus 13 for superheating mixed vapor 13: Vacuum pump 14: Cooling apparatus (trap)
15: Cooling device 16: Side pipe opening

Claims (3)

From a reaction mixture in which a methyl ester represented by the following chemical formula (1) and an alcohol having 2 or more carbon atoms are reacted in the presence of a catalyst, a mixed vapor containing methanol by-produced and the methyl ester represented by the chemical formula (1) as a raw material is produced. The mixed vapor has a ratio (P ′ _MeOH / P ′ _{MA or MMA} ) of the permeation rate of methanol vapor at 120 ° C. and the permeation rate of raw material acrylic acid methyl ester or methacrylic acid methyl ester vapor to 2 or more. brought into contact with the gas separation membrane withdrawn selectively transmitting methanol, methyl esters of non-transmission of formula (1) is an alcohol methyl ester and having 2 or more carbons of the formula with return to the reaction mixture (1) the by transesterification production side of higher alcohol esters, characterized in that to obtain a higher alcohol ester represented by the following formula (2) .

(In the formula, R ¹ represents a hydrogen atom or a methyl group.)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a residue obtained by removing a hydroxyl group from an alcohol having 2 or more carbon atoms.) ^2. The high-grade material according to claim 1, wherein the gas separation membrane has a methanol vapor permeation rate (P ′ _MeOH ) at 120 ° C. of 1 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg or more. A method for producing an alcohol ester.   The method for producing a higher alcohol ester according to claim 1, wherein the gas separation membrane is an asymmetric polyimide hollow fiber membrane that does not dissolve in parachlorophenol.

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