WO2012033100A1 - Acrylate production process and acrylic acid recovery method - Google Patents

Acrylate production process and acrylic acid recovery method Download PDF

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Publication number
WO2012033100A1
WO2012033100A1 PCT/JP2011/070285 JP2011070285W WO2012033100A1 WO 2012033100 A1 WO2012033100 A1 WO 2012033100A1 JP 2011070285 W JP2011070285 W JP 2011070285W WO 2012033100 A1 WO2012033100 A1 WO 2012033100A1
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Prior art keywords
acrylic acid
alkali metal
phase
metal salt
acrylate
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PCT/JP2011/070285
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French (fr)
Japanese (ja)
Inventor
直和 伊藤
政義 吉川
秀紀 榊原
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東亞合成株式会社
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Priority to JP2012532986A priority Critical patent/JP5561367B2/en
Priority to CN201180042939.9A priority patent/CN103153938B/en
Publication of WO2012033100A1 publication Critical patent/WO2012033100A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives

Definitions

  • the present invention relates to a method for producing acrylate mainly for the recovery and reuse of acrylic acid produced by reaction in the production of acrylate, preferably high-boiling acrylate, and a method for producing and using acrylic acid. Belongs to the technical field and the technical field using acrylic acid.
  • An acrylate is often produced by an esterification reaction of acrylic acid and alcohol in the presence of an acid catalyst.
  • the reaction solution is distilled and purified.
  • the esterification reaction solution containing the reaction solvent is neutralized to remove the acid catalyst and unreacted acrylic acid, and the organic phase and the aqueous phase are separated into two layers. It is produced by separating the layers and further removing the reaction solvent in the organic layer.
  • a method is generally used in which the raw alcohol is reacted as much as possible using an excess of acrylic acid so that no alcohol remains in the reaction solution. It has been adopted.
  • excessive use of acrylic acid necessitates neutralization and water washing to remove unreacted acrylic acid, resulting in not only loss of acrylic acid but also high chemical oxygen demand (COD) values. Includes the problem of producing wastewater.
  • Patent Documents 1 and 2 a method has been proposed in which an esterification reaction liquid is neutralized, an aqueous liquid containing acrylic acid or an alkali metal salt thereof is acidified, and acrylic acid is extracted and recovered with an organic solvent.
  • Patent Documents 1 and 2 since these methods extract and recover with an organic solvent, equipment for performing extraction and equipment for recovering the organic solvent are required, and the acrylic acid concentration in the recovered liquid is as low as 30% by weight or less.
  • the recovered acrylic acid it is necessary to purify it by distillation or the like.
  • JP 2006-213647 A Japanese Patent Laid-Open No. 61-243046
  • An object of the present invention is that an acrylic acid extraction step using an organic solvent is not required, the concentration of acrylic acid in the recovered liquid is high, and the method for producing acrylates excellent in acrylic acid recovery efficiency, and the recovery of acrylic acid Is to provide a method.
  • An acrylate production method in which the following first to fifth steps are sequentially performed.
  • First step A step of stirring and mixing acrylic acid and alcohol in the presence of an acid catalyst to obtain a reaction solution containing acrylate by esterification reaction.
  • Second step An alkaline aqueous solution is added to the reaction solution obtained in the first step. After neutralization by addition, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered.
  • Step 4 The liquid obtained in the third step is divided into two phases, a phase containing a large amount of acrylic acid and / or its alkali metal salt (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer).
  • Step 5 of separating The liquid obtained in the fourth step Step of separating the phase (lower layer) containing a large amount of acid alkali metal salt and recovering the remaining acrylic acid and / or the phase (upper layer) containing a large amount of the alkali metal salt
  • the following 3 ′ step to 5 ′ step are sequentially performed A method for recovering acrylic acid to be carried out.
  • 3 'process It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step:
  • the liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid.
  • Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
  • an extraction step of acrylic acid with an organic solvent is unnecessary, and acrylic acid can be easily recovered by a simple method of removing the lower layer liquid separated into two phases.
  • the acrylic acid concentration could be increased, and an acrylate production method and an acrylic acid recovery method excellent in recovery efficiency could be provided.
  • the recovered acrylic acid can be reused in the production of acrylates and polymers as it is or after purification.
  • the present invention relates to a method for producing an acrylate characterized by sequentially performing the following first to fifth steps.
  • First step A step of stirring and mixing acrylic acid and alcohol in the presence of an acid catalyst to obtain a reaction solution containing acrylate by esterification reaction.
  • Second step An alkaline aqueous solution is added to the reaction solution obtained in the first step. After neutralization by addition, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered.
  • Step 4 The liquid obtained in the third step is divided into two phases, a phase containing a large amount of acrylic acid and / or its alkali metal salt (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer).
  • Step 5 of separating The liquid obtained in the fourth step A step of separating a phase (lower layer) containing a large amount of acid alkali metal salt and recovering a remaining phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt.
  • the present invention relates to a method for recovering acrylic acid, characterized in that the 5 ′ step is sequentially performed.
  • 3 'process It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step:
  • the liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid.
  • Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
  • Production method of acrylate According to the production method of acrylate of the present invention, it is possible to produce various acrylates, which can be preferably applied to the production of high-boiling acrylates, and the boiling point under a pressure of 13.3 kPa is particularly 100 ° C. It is preferably applicable to the production of acrylates.
  • Examples of the acrylate having a boiling point of 100 ° C. or higher under a pressure of 13.3 kPa include: Acrylates of alkylene oxide adducts of phenols, such as acrylates of phenol alkylene oxide adducts, acrylates of nonylphenol alkylene oxide adducts and acrylates of p-cumylphenol alkylene oxide adducts; Acrylate of 2-ethylhexyl alcohol alkylene oxide adduct; Polycyclic alkyl acrylates such as acrylates of tricyclodecane dimethylol; Polycyclic alkyl diacrylates such as tricyclodecane dimethylol diacrylate; Mono- or diacrylates of alkylene glycols such as mono- or diacrylates of ethylene glycol, mono- or diacrylates of propylene glycol, mono- or diacrylates of pentanediol and mono- or diacrylates of hexanediol;
  • acrylates those that are more suitable for the production of hydrophobic acrylates than hydrophilic acrylates such as mono- or diacrylates of alkylene glycol, in that the acrylate can be prevented from dissolving on the aqueous phase side in the first step described later. It is.
  • the esterification reaction may be performed according to a conventional method, and examples thereof include a method of heating and stirring acrylic acid and a high-boiling alcohol in an organic solvent in the presence of an acid catalyst.
  • Alkylene oxide adducts of phenols such as phenol alkylene oxide adducts, nonyl phenol alkylene oxide adducts and p-cumyl phenol alkylene oxide adducts; 2-ethylhexyl alcohol alkylene oxide adduct; Polycyclic alkyl alcohols such as tricyclodecane dimethylol; Polycyclic alkyl dialcohols such as tricyclodecane dimethylol; Alkylene glycols such as ethylene glycol, propylene glycol, pentanediol and hexanediol; Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol; Glycerins such as glycerin and diglycerin; Alkyl
  • alkylene oxide in the alkylene oxide adduct examples include ethylene oxide and propylene oxide. Further, the addition number of alkylene oxide is preferably 1 to 20. Among these alcohols, as described above, alcohols in which the resulting acrylate is hydrophobic are preferred.
  • the proportion of acrylic acid used may be appropriately set according to the target acrylate, and is preferably 1.0 to 2.0 mol, more preferably 1.1 to 1 mol, based on 1 mol of all hydroxyl groups of the high boiling alcohol. .5 moles.
  • the acid catalyst examples include mineral acids such as sulfuric acid, and sulfonic acids such as p-toluenesulfonic acid, methanesulfonic acid, and trifluoromethanesulfonic acid.
  • the use ratio of the acid catalyst is preferably 0.1 to 10% by weight based on the weight of the reaction solution containing the organic solvent.
  • the esterification reaction may be carried out according to a conventional method.
  • the reaction temperature may be appropriately set according to the raw materials to be used and the purpose, but is preferably 65 to 140 ° C., more preferably 75 to 120 ° C. from the viewpoint of shortening the reaction time and preventing polymerization.
  • the reaction temperature 65 ° C. or higher the esterification reaction can be carried out quickly and the yield can be prevented from decreasing.
  • the reaction temperature 140 ° C. or lower the thermal polymerization of acrylic acid or the produced acrylate Can be prevented.
  • the pressure in the reaction may be normal pressure or reduced pressure. As described later, for the purpose of preventing thermal polymerization of acrylic acid or the generated acrylate, it is preferable to carry out under reduced pressure.
  • organic solvents include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as hexane and heptane, and alicyclic hydrocarbons such as cyclohexane.
  • the amount of the organic solvent used is preferably 10 to 75% by weight, more preferably 15 to 55% by weight, based on the total amount of the alcohol and acrylic acid.
  • the esterification reaction is preferably performed at 75 to 120 ° C. for the purpose of preventing thermal polymerization of acrylic acid or the produced acrylate.
  • the esterification reaction is preferably performed in the presence of oxygen.
  • the polymerization inhibitor include organic compounds and metal salts.
  • organic compounds examples include benzoquinone, hydroquinone, catechol, diphenylbenzoquinone, hydroquinone monomethyl ether, naphthoquinone, t-butylcatechol, t-butylphenol, dimethyl-t-butylphenol, t-butylcresol, dibutylhydroxytoluene and phenothiazine. It is done.
  • the metal salt include metal copper compounds such as cupric chloride and copper sulfate, and metal iron compounds such as ferrous sulfate.
  • the addition amount of the polymerization inhibitor is preferably 10 to 50,000 ppm by weight and more preferably 100 to 10,000 ppm by weight with respect to the amount of acrylic acid used as a raw material.
  • the polymerization preventing effect can be made sufficient, and by making it 10,000 ppm or less, coloring can be prevented or the curability of the product can be prevented from being lowered.
  • the degree of progress of the esterification reaction is monitored by monitoring the amount of water produced by the esterification reaction, that is, the amount of dehydration, analyzing the acid concentration in the reaction solution, and analyzing the composition of the product acrylate. Judgment is made by confirming the composition.
  • reaction in the presence of oxygen there are a method of reacting in an atmosphere of an oxygen-containing gas or a reaction while introducing an oxygen-containing gas into a reaction solution.
  • a typical oxygen-containing gas is air, but industrially, a gas having an oxygen concentration reduced to 3 to 15% by volume in view of the danger of flammable explosion is preferably used.
  • the oxygen-containing gas can be prepared by mixing oxygen or air and an inert gas. Nitrogen or argon is commonly used as the inert gas.
  • Second step In the second step, an aqueous alkali solution is added to the reaction solution obtained in the first step for neutralization, and then the organic phase is separated into two phases, an organic phase and an aqueous phase, and an acrylate is obtained. Is a step of recovering.
  • an alkaline aqueous solution By adding an alkaline aqueous solution to the reaction liquid obtained in the first step, it is possible to separate and remove acids such as acrylic acid and an acid catalyst from the reaction liquid with an alkaline aqueous solution.
  • alkali component examples include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal salts such as sodium carbonate, and alkaline earth metals such as calcium hydroxide. It is done. Among these, alkali metal hydroxides are preferable because of high neutralization effect.
  • the amount of the alkali component in the aqueous alkali solution is preferably 1 or more, and more preferably 1.0 to 1.6 times in terms of molar ratio to the acid content of the reaction solution. When the amount is within the above range, the acid content is sufficiently neutralized.
  • the concentration of the aqueous alkaline solution is preferably 1 to 25% by weight, more preferably 3 to 25% by weight, and particularly preferably 10 to 25% by weight. When the concentration is 1% by weight or more, it is possible to prevent an increase in the amount of waste water after the neutralization treatment, and when it is 25% by weight or less, the acrylate can prevent polymerization.
  • the neutralization treatment in the second step is performed by supplying the reaction solution and the alkaline aqueous solution to a tank apparatus and stirring them, or using a static mixer or the like.
  • an organic solvent can be added to the reaction solution before neutralization.
  • the reaction solution obtained in the first step is neutralized by adding an alkaline aqueous solution, and then separated into two phases, an organic phase and an aqueous phase.
  • the neutralization treatment can be performed in a plurality of times.
  • the reaction solution can be washed with water for various purposes.
  • the copper polymerization inhibitor when used in the esterification reaction, the copper polymerization inhibitor can be efficiently removed, which is preferable.
  • a method for the water washing treatment a conventional method may be followed. Specifically, a method of adding water to the reaction solution obtained by the esterification reaction, stirring and mixing, and the like may be mentioned. As water, it is preferable to use pure water.
  • the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered.
  • the lower aqueous phase may be extracted.
  • the extracted aqueous phase is subjected to a third step which will be described later.
  • the organic solvent can be removed to make the acrylate of the final product, if necessary.
  • the solvent removal treatment may be carried out in accordance with a conventional method, for example, a method in which the solvent removal tank is decompressed and the organic solvent is removed.
  • the degree of vacuum in the solvent removal tank may be appropriately set according to the raw material to be used and the purpose, and is preferably 0.5 to 50 kPa, and a method of gradually increasing the degree of vacuum depending on the degree of solvent removal is preferable.
  • this solvent removal treatment is performed under reduced pressure while supplying oxygen or adding a polymerization inhibitor and maintaining the temperature at, for example, 20 ° C. or more and 80 ° C. or less. Is preferred.
  • the organic solvent is removed from the organic phase in the solvent removal process in the solvent removal tank, a filter aid is supplied to the solvent removal tank, and the vertical horizontal filter type filter connected to the solvent removal tank is used.
  • the reaction product can also be filtered by depositing a filter aid.
  • the organic layer can be washed with water before the solvent removal treatment as necessary.
  • the third step fractionates the aqueous phase obtained in the second step [hereinafter referred to as the aqueous phase (2). ]
  • a sulfuric acid aqueous solution having a sulfuric acid concentration of 70% by weight or more was added thereto, the pH was adjusted to 4.0 or lower, and the acrylic acid and / or its alkali metal salt content in the liquid was 18% in terms of acrylic acid. % Or more.
  • the sulfuric acid concentration of the sulfuric acid aqueous solution used in the third step is 70% by weight or more. When less than 70% by weight is used, two-phase separation in the fourth step becomes difficult, and the recovery rate of acrylic acid (salt) decreases.
  • the sulfuric acid concentration of the aqueous sulfuric acid solution is preferably 75% by weight or more, preferably 100% by weight or less, and more preferably 99% by weight or less.
  • an aqueous sulfuric acid solution is added to the aqueous phase (2) to adjust the pH to 4.0 or less.
  • the pH of the preferred aqueous phase is in the range of 0 to 4.0, more preferably in the range of 1 to 3.5.
  • the amount of the sulfuric acid aqueous solution added to the aqueous phase (2) is arbitrary as long as the pH of the aqueous phase is 4.0 or less.
  • the temperature is preferably 25 ° C. or more, more preferably 25 to 40 ° C., and particularly preferably 30 to 40 ° C. By setting this temperature to 25 ° C. or higher, it is possible to prevent the sulfate from being precipitated in the third step.
  • acrylic acid and / or an alkali metal salt thereof in the liquid [hereinafter referred to as “acrylic acid (salt)”].
  • acrylic acid (salt) Is 18% by weight or more and preferably 60% by weight or less in terms of acrylic acid.
  • the content is preferably 20% by weight or more, particularly preferably 20 to 60% by weight. If this proportion is lower than 18% by weight, two-phase separation cannot be performed in the fourth step.
  • Examples of the method for setting the content ratio of acrylic acid (salt) in the liquid to 18% by weight or more in terms of acrylic acid include a method of adjusting the concentration of the aqueous alkali solution used in the second step and the amount of the aqueous alkali solution used. .
  • the content rate of acrylic acid (salt) in a liquid is less than 18 weight%, water is distilled off or acrylic acid (salt) is added, and the content rate of acrylic acid (salt) is the said. It can also be a percentage.
  • the ratio of acrylic acid (salt) in the liquid can be measured by methods such as liquid chromatography, gas chromatography, and ion chromatography. In this case, a calibration curve is prepared in advance using acrylic acid (salt), and the ratio can be determined by correcting the measured value by the absolute calibration curve method. When measured as an acrylate, it is converted to acrylic acid by calculation.
  • Patent Document 1 Japanese Patent Laid-Open No. 2006-213647
  • Patent Document 2 Japanese Patent Laid-Open No. 61-243046
  • the acrylic acid concentration in the aqueous phase described in Example 3 was 15.5 wt%, and none of them was separated into two phases.
  • the inventors of the present invention have not disclosed or disclosed in the above-mentioned known literature at all by setting the acrylic acid (salt) concentration in the liquid to a specific value, which is not disclosed in the above-mentioned known literature. It has been found that two-phase separation can be achieved.
  • the liquid obtained in the third step is separated into two phases: a phase containing a large amount of acrylic acid (salt) (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer). It is a process to do.
  • the temperature is preferably 25 to 40 ° C, more preferably 30 to 40 ° C. By maintaining in this temperature range, precipitation of sulfate can be prevented.
  • the method of separating into two phases of a phase (upper layer) rich in acrylic acid (salt) and a phase (lower layer) rich in alkali metal sulfate is not particularly limited, but the specific gravity difference Are preferably used, and examples thereof include a stationary separation method and a centrifugation method.
  • the liquid obtained in the third step may be allowed to stand at the above-mentioned preferable temperature for a certain period of time.
  • Fifth step is to separate a phase (lower layer) containing a large amount of alkali metal sulfate of the liquid obtained in the fourth step, and a remaining phase (upper layer) containing a large amount of acrylic acid (salt). It is a process to collect.
  • phase By a 4th process, it is made to isolate
  • the ratio of acrylic acid (salt) in the recovered phase varies depending on the raw materials and conditions used, but an aqueous solution containing 25 to 60% by weight of acrylic acid (salt) is preferably obtained.
  • the recovered aqueous solution of acrylic acid (salt) varies depending on the processing conditions, but is obtained as an aqueous solution containing acrylic acid as a main component and slightly containing an alkali metal salt of acrylic acid.
  • the recovered aqueous solution of acrylic acid (salt) can be used as it is, or it can be purified and used, and acrylic acid can be separated and used.
  • the recovered aqueous solution of acrylic acid (salt) can be suitably used for the production of polyacrylic acid or polyacrylate by polymerizing as it is without purification depending on the intended use.
  • the obtained polyacrylic acid and polyacrylic acid salt (preferably sodium salt) can be suitably used for applications such as a dispersant, a thickener and a flocculant.
  • the acrylic acid (salt) aqueous solution can be purified prior to the polymerization, and the purified acrylic acid (salt) aqueous solution can be used for the polymerization.
  • acrylic acid When separating and using acrylic acid from the recovered aqueous solution of acrylic acid (salt), an organic solvent such as toluene is added to the recovered aqueous solution of acrylic acid (salt) and heated to distill off water azeotropically. A method is mentioned.
  • the obtained acrylic acid can be used as a raw material for producing polymers and acrylates. It can also be used as a raw material acrylic acid in the first step.
  • the treatment method for the phase containing a large amount of alkali metal sulfate extracted from the treatment tank as the lower layer is not particularly limited, but can be subjected to combustion treatment as it is.
  • the solution can be cooled to separate the alkali metal sulfate as crystals. It is also possible to recover the aqueous solution of acrylic acid (salt) by distilling off the water and then separating the precipitated sulfate.
  • Acrylic acid recovery method The acrylic acid recovery method of the present invention is characterized by sequentially performing the following third to fifth steps.
  • 3 'process It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step:
  • the liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid.
  • Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
  • Step 3 ′ contains acrylic acid and / or its alkali metal salt, alkali metal sulfate salt, and water, has a pH of 4.0 or less, and acrylic acid and / or its This is a step of preparing a liquid having an alkali metal salt content of 18% by weight or more in terms of acrylic acid.
  • the pH of the liquid obtained in the third 3 ′ step is in the range of 4.0 or less, preferably in the range of 0 to 4.0, and more preferably in the range of 1 to 3.5.
  • the content ratio of acrylic acid and / or its alkali metal salt in the liquid obtained in the third step is 18% by weight or more and preferably 60% by weight or less in terms of acrylic acid.
  • the content is preferably 20% by weight or more, particularly preferably 20 to 60% by weight. If the content is less than 18% by weight, two-phase separation cannot be performed in the 4 ′ step.
  • the alkali metal salt of acrylic acid and the alkali metal sulfate alkali metal salt are not particularly limited, but sodium salt and potassium salt are preferably mentioned, and the sodium salt is More preferably.
  • the liquid obtained by a 3 'process is a liquid obtained through the 3rd process from the 1st process in the manufacturing method of the acrylate of the said invention.
  • the temperature of the liquid in the 3 ′ step is preferably 25 ° C. or higher, more preferably 25 to 40 ° C., and particularly preferably 30 to 40 ° C. By setting the temperature of the liquid to 25 ° C. or higher, it is possible to prevent the sulfate from being precipitated in the third ′ step.
  • Step 4 'Step 4' step is a step in which the liquid obtained in step 3 'is a phase (upper layer) containing a large amount of acrylic acid and / or an alkali metal salt thereof and a phase containing a large amount of an alkali metal sulfate ( It is a step of separating into two phases of the lower layer.
  • 4th process is synonymous with 4th process except using the liquid obtained at 3 'process instead of the liquid obtained at 3rd process, and its preferable aspect is also the same.
  • Step 5 'Step 5' step is to separate a phase (lower layer) containing a large amount of alkali metal sulfate in the liquid obtained in step 4 ', and to leave the remaining acrylic acid and / or alkali metal salt thereof.
  • This is a step of recovering a phase (upper layer) containing a large amount.
  • 5th process is synonymous with 5th process except using the liquid obtained at 4 'process instead of the liquid obtained at 4th process, and its preferable aspect is also the same.
  • the acrylic acid (salt) aqueous solution recovered by the acrylic acid recovery method of the present invention varies depending on the processing conditions, but is obtained as an aqueous solution containing acrylic acid as a main component and slightly containing an alkali metal salt of acrylic acid.
  • the recovered aqueous solution of acrylic acid (salt) can be used as it is, or it can be purified and used, and acrylic acid can be separated and used.
  • acrylic acid and / or an alkali metal salt thereof may be isolated and / or purified from an aqueous solution of acrylic acid (salt) recovered by the acrylic acid recovery method of the present invention by a known method.
  • the recovered aqueous solution of acrylic acid (salt) is polymerized as it is without purification depending on the intended use, so that polyacrylic acid or polyacrylic acid can be obtained. It can be suitably used for the production of acrylates.
  • % means% by weight.
  • Example 1 3,000 g of acrylic acid, 1,470 g of dipentaerythritol (hereinafter referred to as “DPET”), 70 g of 78% sulfuric acid, 10 g of hydroquinone (hereinafter referred to as “HQ”) and 2,450 g of toluene were charged into a 10 L reaction kettle. It heated in the oil bath set to 100 degreeC under the pressure of 53 kPa, and it was made to react for 10 hours, removing condensed water as azeotropic water with toluene. The reaction liquid weight at this time was 6,250 g. After completion of the reaction, 3,500 g of toluene was added.
  • DPET dipentaerythritol
  • HQ hydroquinone
  • the upper layer (organic phase) was further added with 1,360 g of a 20% aqueous sodium hydroxide solution, stirred, allowed to stand, and separated into an upper layer (organic phase) and a lower layer (aqueous phase).
  • 400 g of pure water was added and stirred, then allowed to stand, and separated into an upper layer (organic phase) and a lower layer (aqueous phase) of 8,660 g.
  • MQ hydroquinone monomethyl ether
  • Example 2 To 300 g of the neutralized wastewater obtained in Example 1, 78% sulfuric acid was gradually added until the pH reached 3. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The added 78% sulfuric acid was 59.0 g. Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer). The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted. The obtained upper acrylic acid aqueous solution layer was 151.8 g, the acrylic acid concentration was 37.4%, and 76.7% acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. did it.
  • Example 3 To 300 g of the neutralized wastewater obtained in Example 1, 98% sulfuric acid was gradually added until pH 2 was reached. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The added 98% sulfuric acid was 52.1 g. Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer). The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted. The obtained upper acrylic acid aqueous solution layer was 128.4 g, the acrylic acid concentration was 44.6%, and 77.4% of acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. It was.
  • Example 2 (Comparative Example 2) The supplementary examination of Example 1 in patent document 1 was implemented. That is, 2,000 g of acrylic acid, 1,200 g of DPET, 50 g of 78% sulfuric acid, 10 g of HQ, and 2,450 g of toluene were charged into a 10 L flask, heated in an oil bath set at 120 ° C. under a pressure of 60 kPa, and condensed water was added to toluene. The mixture was reacted for 10 hours while removing as azeotropic water. The reaction liquid weight at this time was 6,900 g.
  • Example 4 3,000 g of acrylic acid, 1,600 g of pentaerythritol, 70 g of 78% sulfuric acid, MQ 7 g, and 2,000 g of toluene are charged into a 10 L reaction kettle, heated in an oil bath set at 100 ° C. under a pressure of 50 kPa, and condensed water is added. The reaction was allowed to proceed for 6 hours while removing. The reaction solution weight at this time was 6,100 g. After completion of the reaction, 3,500 g of toluene was added.
  • the reaction kettle was charged with 40 g of ion exchange water, heated to 80 ° C. with nitrogen sealing, and 1 g of 10% aqueous sodium persulfate solution was added. Subsequently, a monomer solution obtained by dissolving 5 g of sodium hypophosphite in 210 g of the acrylic acid aqueous solution recovered in Example 2 and 10 g of a 10% sodium persulfate aqueous solution were reacted from separate injection ports while maintaining a polymerization temperature of 80 ° C. The solution was continuously added dropwise to the vessel for 4 hours to obtain a polyacrylic acid aqueous solution.
  • the acrylate production method of the present invention can be used for the production of acrylates, more preferably for the production of high-boiling acrylates.
  • the separated and recovered acrylic acid can be used for the production of acrylates and polymers. Can be reused.
  • the acrylic acid separated and recovered by the acrylic acid recovery method of the present invention can be reused in the production of acrylates and polymers.

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Abstract

The purpose of the present invention is to provide: an acrylate production process which does not require a step of extracting acrylic acid with an organic solvent, enables the increase in concentration of acrylic acid in a solution from which an acrylate is to be recovered, and has excellent acrylic acid recovery efficiency; and an acrylic acid recovery method. This acrylate production process and this acrylic acid recovery method are characterized in that a solution which comprises acrylic acid and/or an alkali metal salt thereof, an alkali metal salt of sulfuric acid and water, has a content of acrylic acid and/or the alkali metal salt thereof of equal to or more than a specific value, and has a specified pH value is separated into two phases, i.e., a phase (an upper phase) containing acrylic acid and/or the alkali metal salt thereof in a larger amount and a phase (a lower phase) containing the alkali metal salt of sulfuric acid in a larger amount.

Description

アクリレートの製造方法、及び、アクリル酸の回収方法Acrylate production method and acrylic acid recovery method
　本発明は、アクリレート、好ましくは高沸点のアクリレートの製造において、反応で生じるアクリル酸の回収・再使用を主目的とするアクリレートの製造方法、及び、アクリル酸の回収方法に関し、アクリレートを製造・使用する技術分野及びアクリル酸を使用する技術分野に属する。 The present invention relates to a method for producing acrylate mainly for the recovery and reuse of acrylic acid produced by reaction in the production of acrylate, preferably high-boiling acrylate, and a method for producing and using acrylic acid. Belongs to the technical field and the technical field using acrylic acid.
　アクリレートは、アクリル酸とアルコールとを、酸触媒の存在下にエステル化反応させて製造されることが多い。
　低沸点アクリレートの製造では、反応液を蒸留して精製される。
　一方、高沸点アクリレートの製造においては蒸留が容易でないため、反応溶媒を含むエステル化反応液を中和して酸触媒及び未反応アクリル酸を除去し、有機相と水相の２層分離した有機層を分離し、さらに有機層中の反応溶媒を脱溶剤して製造される。この場合、目的物であるアクリレートと原料アルコールの分離が困難なため、アクリル酸を過剰に使用して原料アルコールをなるべく多く反応させ、反応液中にアルコールが残らないようにする方法が一般的に採用されている。
　しかしながら、アクリル酸を過剰に用いると、未反応アクリル酸を除去する中和・水洗を行う必要が生じ、その結果、アクリル酸をロスするばかりか、化学的酸素要求量（ＣＯＤ）の値の高い廃水を生じるという問題を含んでいる。 An acrylate is often produced by an esterification reaction of acrylic acid and alcohol in the presence of an acid catalyst.
In the production of low boiling point acrylate, the reaction solution is distilled and purified.
On the other hand, since distillation is not easy in the production of high-boiling acrylates, the esterification reaction solution containing the reaction solvent is neutralized to remove the acid catalyst and unreacted acrylic acid, and the organic phase and the aqueous phase are separated into two layers. It is produced by separating the layers and further removing the reaction solvent in the organic layer. In this case, since it is difficult to separate the target acrylate and the raw alcohol, a method is generally used in which the raw alcohol is reacted as much as possible using an excess of acrylic acid so that no alcohol remains in the reaction solution. It has been adopted.
However, excessive use of acrylic acid necessitates neutralization and water washing to remove unreacted acrylic acid, resulting in not only loss of acrylic acid but also high chemical oxygen demand (COD) values. Includes the problem of producing wastewater.
　上記の問題を解決するために、エステル化反応液を中和し、アクリル酸又はそのアルカリ金属塩を含有する水性液を酸性化し、有機溶剤によりアクリル酸を抽出回収する方法が提案されている（特許文献１及び２）。
　しかし、これらの方法は、有機溶剤で抽出回収するため、抽出を行うための設備、有機溶剤を回収するための設備が必要になること、回収液中のアクリル酸濃度は３０重量％以下と低く、回収したアクリル酸を再利用するには蒸留等により精製する必要があること等、十分とはいえない状況にある。 In order to solve the above problems, a method has been proposed in which an esterification reaction liquid is neutralized, an aqueous liquid containing acrylic acid or an alkali metal salt thereof is acidified, and acrylic acid is extracted and recovered with an organic solvent ( Patent Documents 1 and 2).
However, since these methods extract and recover with an organic solvent, equipment for performing extraction and equipment for recovering the organic solvent are required, and the acrylic acid concentration in the recovered liquid is as low as 30% by weight or less. In order to reuse the recovered acrylic acid, it is necessary to purify it by distillation or the like.
特開２００６－２１３６４７号公報JP 2006-213647 A 特開昭６１－２４３０４６号公報Japanese Patent Laid-Open No. 61-243046
　本発明の目的は、有機溶剤によるアクリル酸の抽出工程が不要であり、回収液中のアクリル酸濃度を高濃度とし、アクリル酸の回収効率に優れたアクリレートの製造方法、及び、アクリル酸の回収方法を提供することである。 An object of the present invention is that an acrylic acid extraction step using an organic solvent is not required, the concentration of acrylic acid in the recovered liquid is high, and the method for producing acrylates excellent in acrylic acid recovery efficiency, and the recovery of acrylic acid Is to provide a method.
　本発明者らは、前記課題を解決するため鋭意検討した結果、以下に示す本発明のアクリレートの製造方法、及び、アクリル酸の回収方法を完成した。
　下記第１工程～第５工程を順次実施するアクリレートの製造方法。
第１工程：酸触媒の存在下に、アクリル酸とアルコールを攪拌・混合し、エステル化反応させアクリレートを含む反応液を得る工程
第２工程：第１工程で得られた反応液にアルカリ水溶液を添加して中和した後、有機相と水相の２相に分離させ、有機相を分取し、アクリレートを回収する工程
第３工程：第２工程で得られた水相を分取し、これに硫酸濃度７０重量％以上の硫酸水溶液を添加し、ｐＨを４．０以下に調整し、かつ液中のアクリル酸及び／又はそのアルカリ金属塩の含有割合をアクリル酸換算で１８重量％以上とする工程
第４工程：第３工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
第５工程：第４工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程
　下記第３’工程～第５’工程を順次実施するアクリル酸の回収方法。
第３’工程：アクリル酸及び／又はそのアルカリ金属塩、硫酸アルカリ金属塩、並びに、水を含有し、ｐＨが４．０以下であり、かつアクリル酸及び／又はそのアルカリ金属塩の含有割合がアクリル酸換算で１８重量％以上である液を調製する工程
第４’工程：第３’工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
第５’工程：第４’工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程 As a result of intensive studies to solve the above problems, the present inventors have completed the following acrylate production method and acrylic acid recovery method of the present invention.
An acrylate production method in which the following first to fifth steps are sequentially performed.
First step: A step of stirring and mixing acrylic acid and alcohol in the presence of an acid catalyst to obtain a reaction solution containing acrylate by esterification reaction. Second step: An alkaline aqueous solution is added to the reaction solution obtained in the first step. After neutralization by addition, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered. Third step: The aqueous phase obtained in the second step is separated, A sulfuric acid aqueous solution having a sulfuric acid concentration of 70% by weight or more was added thereto, the pH was adjusted to 4.0 or less, and the content of acrylic acid and / or alkali metal salt thereof in the liquid was 18% by weight or more in terms of acrylic acid. Step 4: The liquid obtained in the third step is divided into two phases, a phase containing a large amount of acrylic acid and / or its alkali metal salt (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer). Step 5 of separating: The liquid obtained in the fourth step Step of separating the phase (lower layer) containing a large amount of acid alkali metal salt and recovering the remaining acrylic acid and / or the phase (upper layer) containing a large amount of the alkali metal salt The following 3 ′ step to 5 ′ step are sequentially performed A method for recovering acrylic acid to be carried out.
3 'process: It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step: The liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid. Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step: The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
　本発明によれば、有機溶剤によるアクリル酸の抽出工程が不要であり、２相分離した下層の液を除去するという簡便な方法で容易にアクリル酸を回収することができ、しかも回収液中のアクリル酸濃度を高濃度とすることができ、回収効率に優れたアクリレートの製造方法、及び、アクリル酸の回収方法を提供することができた。
　また、回収されたアクリル酸は、そのまま又は精製して、アクリレートやポリマーの製造に再使用することができる。 According to the present invention, an extraction step of acrylic acid with an organic solvent is unnecessary, and acrylic acid can be easily recovered by a simple method of removing the lower layer liquid separated into two phases. The acrylic acid concentration could be increased, and an acrylate production method and an acrylic acid recovery method excellent in recovery efficiency could be provided.
The recovered acrylic acid can be reused in the production of acrylates and polymers as it is or after purification.
　以下、本発明を詳細に説明する。
　本発明は、下記第１工程～第５工程を順次実施することを特徴とするアクリレートの製造方法に関する。
第１工程：酸触媒の存在下に、アクリル酸とアルコールを攪拌・混合し、エステル化反応させアクリレートを含む反応液を得る工程
第２工程：第１工程で得られた反応液にアルカリ水溶液を添加して中和した後、有機相と水相の２相に分離させ、有機相を分取し、アクリレートを回収する工程
第３工程：第２工程で得られた水相を分取し、これに硫酸濃度７０重量％以上の硫酸水溶液を添加し、ｐＨを４．０以下に調整し、かつ液中のアクリル酸及び／又はそのアルカリ金属塩の含有割合をアクリル酸換算で１８重量％以上とする工程
第４工程：第３工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
第５工程：第４工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程
　また、本発明は、下記第３’工程～第５’工程を順次実施することを特徴とするアクリル酸の回収方法に関する。
第３’工程：アクリル酸及び／又はそのアルカリ金属塩、硫酸アルカリ金属塩、並びに、水を含有し、ｐＨが４．０以下であり、かつアクリル酸及び／又はそのアルカリ金属塩の含有割合がアクリル酸換算で１８重量％以上である液を調製する工程
第４’工程：第３’工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
第５’工程：第４’工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程 Hereinafter, the present invention will be described in detail.
The present invention relates to a method for producing an acrylate characterized by sequentially performing the following first to fifth steps.
First step: A step of stirring and mixing acrylic acid and alcohol in the presence of an acid catalyst to obtain a reaction solution containing acrylate by esterification reaction. Second step: An alkaline aqueous solution is added to the reaction solution obtained in the first step. After neutralization by addition, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered. Third step: The aqueous phase obtained in the second step is separated, A sulfuric acid aqueous solution having a sulfuric acid concentration of 70% by weight or more was added thereto, the pH was adjusted to 4.0 or less, and the content of acrylic acid and / or alkali metal salt thereof in the liquid was 18% by weight or more in terms of acrylic acid. Step 4: The liquid obtained in the third step is divided into two phases, a phase containing a large amount of acrylic acid and / or its alkali metal salt (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer). Step 5 of separating: The liquid obtained in the fourth step A step of separating a phase (lower layer) containing a large amount of acid alkali metal salt and recovering a remaining phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt. The present invention relates to a method for recovering acrylic acid, characterized in that the 5 ′ step is sequentially performed.
3 'process: It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step: The liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid. Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step: The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
１．アクリレートの製造方法
　本発明のアクリレートの製造方法によれば、種々のアクリレートを製造することが可能であり、高沸点アクリレートの製造に好ましく適用でき、特に１３．３ｋＰａの圧力下の沸点が１００℃以上のアクリレートの製造に好ましく適用できる。 1. Production method of acrylate According to the production method of acrylate of the present invention, it is possible to produce various acrylates, which can be preferably applied to the production of high-boiling acrylates, and the boiling point under a pressure of 13.3 kPa is particularly 100 ° C. It is preferably applicable to the production of acrylates.
　１３．３ｋＰａの圧力下の沸点が１００℃以上のアクリレートとしては、例えば、
フェノールアルキレンオキサイド付加物のアクリレート、ノニルフェノールアルキレンオキサイド付加物のアクリレート及びｐ－クミルフェノールアルキレンオキサイド付加物のアクリレート等のフェノール類のアルキレンオキサイド付加物のアクリレート；
２－エチルヘキシルアルコールアルキレンオキサイド付加物のアクリレート；
トリシクロデカンジメチロールのアクリレート等の多環式アルキルアクリレート；
トリシクロデカンジメチロールジアクリレート等の多環式アルキルジアクリレート；
エチレングリコールのモノ又はジアクリレート、プロピレングリコールのモノ又はジアクリレート、ペンタンジオールのモノ又はジアクリレート及びヘキサンジオールのモノ又はジアクリレート等のアルキレングリコールのモノ又はジアクリレート；
ジエチレングリコールのモノ又はジアクリレート、トリエチレングリコールのモノ又はジアクリレート、テトラエチレングリコールのモノ又はジアクリレート、ポリエチレングリコールのモノ又はジアクリレート、ジプロピレングリコールのモノ又はジアクリレート、トリプロピレングリコールのモノ又はジアクリレート及びポリプロピレングリコールのモノ又はジアクリレート等のポリアルキレングリコールのモノ又はジアクリレート；
グリセリンのジ又はトリアクリレート及びジグリセリンのジ又はトリアクリレート等のグリセリン類のジ又はトリアクリレート；グリセリン類のアルキレンオキサイド付加物のジ又はトリアクリレート；
ビスフェノールＡアルキレンオキサイド付加物のモノ又はジアクリレート及びビスフェノールＦアルキレンオキサイド付加物のモノ又はジアクリレート等のビスフェノールアルキレンオキサイド付加物のモノ又はジアクリレート；
トリメチロールプロパントリアクリレート、ジトリメチロールプロパントリアクリレート、ジトリメチロールプロパンテトラアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、ジペンタエリスリトールペンタ（メタ）アクリレート及びジペンタエリスリトールヘキサアクリレート等のポリオールポリアクリレート；これらポリオールのアルキレンオキサイド付加物のポリ（メタ）アクリレート；
イソシアヌル酸アルキレンオキサイド付加物のジ又はトリ（メタ）アクリレート；並びにポリエステルアクリレート等が挙げられる。
　アルキレンオキサイド付加物におけるアルキレンオキサイドとしては、エチレンオキサイド及びプロピレンオキサイド等が挙げられる。また、アルキレンオキサイドの付加数としては、１～２０が好ましい。 Examples of the acrylate having a boiling point of 100 ° C. or higher under a pressure of 13.3 kPa include:
Acrylates of alkylene oxide adducts of phenols, such as acrylates of phenol alkylene oxide adducts, acrylates of nonylphenol alkylene oxide adducts and acrylates of p-cumylphenol alkylene oxide adducts;
Acrylate of 2-ethylhexyl alcohol alkylene oxide adduct;
Polycyclic alkyl acrylates such as acrylates of tricyclodecane dimethylol;
Polycyclic alkyl diacrylates such as tricyclodecane dimethylol diacrylate;
Mono- or diacrylates of alkylene glycols such as mono- or diacrylates of ethylene glycol, mono- or diacrylates of propylene glycol, mono- or diacrylates of pentanediol and mono- or diacrylates of hexanediol;
Diethylene glycol mono or diacrylate, triethylene glycol mono or diacrylate, tetraethylene glycol mono or diacrylate, polyethylene glycol mono or diacrylate, dipropylene glycol mono or diacrylate, tripropylene glycol mono or diacrylate And polyalkylene glycol mono- or diacrylates such as polypropylene glycol mono- or diacrylate;
Di- or triacrylate of glycerol such as di- or triacrylate of glycerol and di- or triacrylate of diglycerol; Di- or triacrylate of alkylene oxide adduct of glycerol;
Mono or diacrylate of bisphenol alkylene oxide adducts, such as mono or diacrylate of bisphenol A alkylene oxide adduct and mono or diacrylate of bisphenol F alkylene oxide adduct;
Polyol polyacrylates such as trimethylolpropane triacrylate, ditrimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexaacrylate; these polyols A poly (meth) acrylate of an alkylene oxide adduct of
Examples include di- or tri (meth) acrylates of isocyanuric acid alkylene oxide adducts; and polyester acrylates.
Examples of the alkylene oxide in the alkylene oxide adduct include ethylene oxide and propylene oxide. Further, the addition number of alkylene oxide is preferably 1 to 20.
　これらアクリレートの中でも、後記する第１工程で水相側にアクリレートが溶解することを防止できる点で、アルキレングリコールのモノ又はジアクリレート等の親水性アクリレートより、疎水性のアクリレートの製造方法に適するものである。 Among these acrylates, those that are more suitable for the production of hydrophobic acrylates than hydrophilic acrylates such as mono- or diacrylates of alkylene glycol, in that the acrylate can be prevented from dissolving on the aqueous phase side in the first step described later. It is.
　以下、前記した第１工程～第５工程について説明する。 Hereinafter, the first to fifth steps will be described.
１）第１工程
　第１工程では、酸触媒の存在下に、アクリル酸とアルコールを攪拌・混合し、エステル化反応させアクリレートを含む反応液を得る。
　エステル化反応としては、常法に従えば良く、有機溶媒中、酸触媒の存在下にアクリル酸及び高沸点アルコールを加熱・攪拌する方法等が挙げられる。 1) First Step In the first step, acrylic acid and alcohol are stirred and mixed in the presence of an acid catalyst, and esterified to obtain a reaction liquid containing acrylate.
The esterification reaction may be performed according to a conventional method, and examples thereof include a method of heating and stirring acrylic acid and a high-boiling alcohol in an organic solvent in the presence of an acid catalyst.
　アルコールとしては、前記したアクリレートに対応するものを使用すれば良い。
　具体的には、
フェノールアルキレンオキサイド付加物、ノニルフェノールアルキレンオキサイド付加物及びｐ－クミルフェノールアルキレンオキサイド付加物等のフェノール類のアルキレンオキサイド付加物；
２－エチルヘキシルアルコールアルキレンオキサイド付加物；
トリシクロデカンジメチロール等の多環式アルキルアルコール；
トリシクロデカンジメチロール等の多環式アルキルジアルコール；
エチレングリコール、プロピレングリコール、ペンタンジオール及びヘキサンジオール等のアルキレングリコール；
ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、ジプロピレングリコール、トリプロピレングリコール及びポリプロピレングリコール等のポリアルキレングリコール；
グリセリン及びジグリセリン等のグリセリン類；
グリセリン類のアルキレンオキサイド付加物；
ビスフェノールＡアルキレンオキサイド付加物及びビスフェノールＦアルキレンオキサイド付加物等のビスフェノール類アルキレンオキサイド付加物；
トリメチロールプロパン、ジトリメチロールプロパントリアクリレート、ペンタエリスリトールトリアクリレート及びジペンタエリスリトール等のポリオール；
これらポリオールのアルキレンオキサイド付加物；
イソシアヌル酸アルキレンオキサイド付加物；並びにポリエステルポリオール等が挙げられる。
　アルキレンオキサイド付加物におけるアルキレンオキサイドとしては、エチレンオキサイド及びプロピレンオキサイド等が挙げられる。また、アルキレンオキサイドの付加数としては、１～２０が好ましい。
　これらアルコールの中でも、前記した通り、得られるアクリレートが疎水性となるアルコールが好ましい。 As alcohol, what corresponds to an acrylate mentioned above should just be used.
In particular,
Alkylene oxide adducts of phenols such as phenol alkylene oxide adducts, nonyl phenol alkylene oxide adducts and p-cumyl phenol alkylene oxide adducts;
2-ethylhexyl alcohol alkylene oxide adduct;
Polycyclic alkyl alcohols such as tricyclodecane dimethylol;
Polycyclic alkyl dialcohols such as tricyclodecane dimethylol;
Alkylene glycols such as ethylene glycol, propylene glycol, pentanediol and hexanediol;
Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol;
Glycerins such as glycerin and diglycerin;
Alkylene oxide adducts of glycerins;
Bisphenol alkylene oxide adducts such as bisphenol A alkylene oxide adduct and bisphenol F alkylene oxide adduct;
Polyols such as trimethylolpropane, ditrimethylolpropane triacrylate, pentaerythritol triacrylate and dipentaerythritol;
Alkylene oxide adducts of these polyols;
Examples include isocyanuric acid alkylene oxide adducts; and polyester polyols.
Examples of the alkylene oxide in the alkylene oxide adduct include ethylene oxide and propylene oxide. Further, the addition number of alkylene oxide is preferably 1 to 20.
Among these alcohols, as described above, alcohols in which the resulting acrylate is hydrophobic are preferred.
　アクリル酸の使用割合は、目的とするアクリレートに応じて適宜設定すれば良く、高沸点アルコールの全水酸基１モルに対して１．０～２．０モルが好ましく、より好ましくは１．１～１．５モルである。 The proportion of acrylic acid used may be appropriately set according to the target acrylate, and is preferably 1.0 to 2.0 mol, more preferably 1.1 to 1 mol, based on 1 mol of all hydroxyl groups of the high boiling alcohol. .5 moles.
　酸触媒としては、硫酸等の鉱酸、並びにｐ－トルエンスルホン酸、メタンスルホン酸及びトリフルオロメタンスルホン酸等のスルホン酸等が挙げられる。
　酸触媒の使用割合としては、有機溶媒を含む反応液の重量に対して０．１～１０重量％が好ましい。 Examples of the acid catalyst include mineral acids such as sulfuric acid, and sulfonic acids such as p-toluenesulfonic acid, methanesulfonic acid, and trifluoromethanesulfonic acid.
The use ratio of the acid catalyst is preferably 0.1 to 10% by weight based on the weight of the reaction solution containing the organic solvent.
　エステル化反応は、常法に従い実施すれば良い。
　反応温度は、使用する原料及び目的に応じて適宜設定すればよいが、反応時間の短縮と重合防止の観点から６５～１４０℃が好ましく、７５～１２０℃がより好ましい。反応温度を６５℃以上とすることでエステル化反応を迅速に行い、収率の低下を防止することができ、一方反応温度を１４０℃以下とすることで、アクリル酸又は生成したアクリレートの熱重合を防止することができる。
　反応における圧力としては、常圧でも、減圧でも良い。後記する通り、アクリル酸又は生成したアクリレートの熱重合を防止することを目的としては、減圧状態で行うことが好ましい。 The esterification reaction may be carried out according to a conventional method.
The reaction temperature may be appropriately set according to the raw materials to be used and the purpose, but is preferably 65 to 140 ° C., more preferably 75 to 120 ° C. from the viewpoint of shortening the reaction time and preventing polymerization. By making the reaction temperature 65 ° C. or higher, the esterification reaction can be carried out quickly and the yield can be prevented from decreasing. On the other hand, by making the reaction temperature 140 ° C. or lower, the thermal polymerization of acrylic acid or the produced acrylate Can be prevented.
The pressure in the reaction may be normal pressure or reduced pressure. As described later, for the purpose of preventing thermal polymerization of acrylic acid or the generated acrylate, it is preferable to carry out under reduced pressure.
　エステル化反応に際しては、エステル化反応で生成する水を有機溶媒と共沸させながら脱水を促進することが好ましい。
　好ましい有機溶媒としては、例えばトルエン、ベンゼン及びキシレン等の芳香族炭化水素、ヘキサン及びヘプタン等の脂肪族炭化水素並びにシクロヘキサン等の脂環式炭化水素等が挙げられる。
　有機溶媒の使用量は、前記アルコールとアクリル酸の合計量に対して、１０～７５重量％となる割合が好ましく、１５～５５重量％となる割合がより好ましい。 In the esterification reaction, it is preferable to promote dehydration while azeotroping water produced in the esterification reaction with an organic solvent.
Preferred organic solvents include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as hexane and heptane, and alicyclic hydrocarbons such as cyclohexane.
The amount of the organic solvent used is preferably 10 to 75% by weight, more preferably 15 to 55% by weight, based on the total amount of the alcohol and acrylic acid.
　エステル化反応は、アクリル酸又は生成したアクリレートの熱重合を防止することを目的とし、好ましくは７５～１２０℃にて行うことが好ましい。また、重合防止のためにエステル化反応を酸素の存在下で行うことが好ましい。
　同様の目的で、反応液に重合禁止剤を添加することが好ましい。重合禁止剤としては、有機化合物及び金属塩等が挙げられる。
　有機化合物としては、例えば、ベンゾキノン、ハイドロキノン、カテコール、ジフェニルベンゾキノン、ハイドロキノンモノメチルエーテル、ナフトキノン、ｔ－ブチルカテコール、ｔ－ブチルフェノール、ジメチル－ｔ－ブチルフェノール、ｔ－ブチルクレゾール、ジブチルヒドロキシトルエン及びフェノチアジン等が挙げられる。
　金属塩としては、塩化第二銅及び硫酸銅等の金属銅化合物、並びに硫酸第一鉄等の金属鉄化合物等が挙げられる。
　重合禁止剤の添加量は、原料であるアクリル酸の使用量に対して重量で１０～５０，０００ｐｐｍが好ましく、１００～１０，０００ｐｐｍがより好ましい。１００ｐｐｍ以上とすることで重合防止効果を十分にすることができ、１０，０００ｐｐｍ以下とすることで、着色を防止したり、生成物の硬化性低下を防止することができる。
　エステル化反応の進行度は、エステル化反応により生成する水の量、すなわち脱水量を監視したり、反応液中の酸分濃度を分析したり、生成物アクリレートの組成を分析し、目的とする組成であるのかを確認して判断する。 The esterification reaction is preferably performed at 75 to 120 ° C. for the purpose of preventing thermal polymerization of acrylic acid or the produced acrylate. In order to prevent polymerization, the esterification reaction is preferably performed in the presence of oxygen.
For the same purpose, it is preferable to add a polymerization inhibitor to the reaction solution. Examples of the polymerization inhibitor include organic compounds and metal salts.
Examples of organic compounds include benzoquinone, hydroquinone, catechol, diphenylbenzoquinone, hydroquinone monomethyl ether, naphthoquinone, t-butylcatechol, t-butylphenol, dimethyl-t-butylphenol, t-butylcresol, dibutylhydroxytoluene and phenothiazine. It is done.
Examples of the metal salt include metal copper compounds such as cupric chloride and copper sulfate, and metal iron compounds such as ferrous sulfate.
The addition amount of the polymerization inhibitor is preferably 10 to 50,000 ppm by weight and more preferably 100 to 10,000 ppm by weight with respect to the amount of acrylic acid used as a raw material. By making it 100 ppm or more, the polymerization preventing effect can be made sufficient, and by making it 10,000 ppm or less, coloring can be prevented or the curability of the product can be prevented from being lowered.
The degree of progress of the esterification reaction is monitored by monitoring the amount of water produced by the esterification reaction, that is, the amount of dehydration, analyzing the acid concentration in the reaction solution, and analyzing the composition of the product acrylate. Judgment is made by confirming the composition.
　また、前記した酸素存在下の反応としては、具体的には、酸素含有気体の雰囲気下で反応したり、酸素含有気体を反応液中に導入しながら反応する方法がある。典型的な酸素含有気体は空気であるが、工業的には引火爆発危険を考えて酸素濃度３～１５容量％に下げた気体が好適に使用される。酸素含有気体は、酸素又は空気と、不活性ガスを混合することによって調製できる。不活性ガスとしては窒素やアルゴンが常用される。 Further, as the reaction in the presence of oxygen described above, specifically, there are a method of reacting in an atmosphere of an oxygen-containing gas or a reaction while introducing an oxygen-containing gas into a reaction solution. A typical oxygen-containing gas is air, but industrially, a gas having an oxygen concentration reduced to 3 to 15% by volume in view of the danger of flammable explosion is preferably used. The oxygen-containing gas can be prepared by mixing oxygen or air and an inert gas. Nitrogen or argon is commonly used as the inert gas.
２）第２工程
　第２工程は、第１工程で得られた反応液にアルカリ水溶液を添加して中和した後、有機相と水相の２相に分離させ有機相を分取し、アクリレートを回収する工程である。
　第１工程で得られた反応液にアルカリ水溶液で添加することで、反応液からアクリル酸及び酸触媒等の酸分をアルカリ水溶液で分離・除去することができる。 2) Second step In the second step, an aqueous alkali solution is added to the reaction solution obtained in the first step for neutralization, and then the organic phase is separated into two phases, an organic phase and an aqueous phase, and an acrylate is obtained. Is a step of recovering.
By adding an alkaline aqueous solution to the reaction liquid obtained in the first step, it is possible to separate and remove acids such as acrylic acid and an acid catalyst from the reaction liquid with an alkaline aqueous solution.
　中和で使用するアルカリ水溶液において、アルカリ成分としては、水酸化ナトリウム及び水酸化カリウム等のアルカリ金属水酸化物、並びに炭酸ナトリウム等のアルカリ金属塩及び水酸化カルシウム等のアルカリ土類金属等が挙げられる。これらの中でも、アルカリ金属水酸化物が、中和の効果が高い点で好ましい。 In the alkaline aqueous solution used for neutralization, examples of the alkali component include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal salts such as sodium carbonate, and alkaline earth metals such as calcium hydroxide. It is done. Among these, alkali metal hydroxides are preferable because of high neutralization effect.
　アルカリ水溶液におけるアルカリ成分の量は、反応液の酸分に対してモル比で１倍以上が好ましく、より好ましくは１．０～１．６倍である。上記範囲であると、酸分の中和が十分行われる。
　また、アルカリ水溶液の濃度は、１～２５重量％であることが好ましく、より好ましくは３～２５重量％であり、特に好ましくは１０～２５重量％である。この濃度が１重量％以上とすることで中和処理後の排水量が増大することを防止することができ、２５重量％以下とすることで、アクリレートが重合を防止することができる。 The amount of the alkali component in the aqueous alkali solution is preferably 1 or more, and more preferably 1.0 to 1.6 times in terms of molar ratio to the acid content of the reaction solution. When the amount is within the above range, the acid content is sufficiently neutralized.
The concentration of the aqueous alkaline solution is preferably 1 to 25% by weight, more preferably 3 to 25% by weight, and particularly preferably 10 to 25% by weight. When the concentration is 1% by weight or more, it is possible to prevent an increase in the amount of waste water after the neutralization treatment, and when it is 25% by weight or less, the acrylate can prevent polymerization.
　第２工程の中和処理は、反応液及びアルカリ水溶液を、槽型装置に供給して攪拌して処理するか、又はスタティックミキサー等を使用して処理する。尚、比重調整等の目的で、中和前に有機溶媒を反応液に加えることもできる。 The neutralization treatment in the second step is performed by supplying the reaction solution and the alkaline aqueous solution to a tank apparatus and stirring them, or using a static mixer or the like. For the purpose of adjusting specific gravity, an organic solvent can be added to the reaction solution before neutralization.
　第２工程では、第１工程で得られた反応液にアルカリ水溶液を添加して中和した後、有機相と水相の２相に分離させる。当該中和処理は、複数回に分けて実施することもできる。 In the second step, the reaction solution obtained in the first step is neutralized by adding an alkaline aqueous solution, and then separated into two phases, an organic phase and an aqueous phase. The neutralization treatment can be performed in a plurality of times.
●前処理
　中和処理を実施する前において、種々の目的で反応液の水洗処理を行うことができる。
　特に、エステル化反応で銅系の重合禁止剤を使用した場合において、効率的に銅系の重合禁止剤を除去することができ、好ましい。
　水洗処理の方法としては、常法に従えば良く、具体的には、エステル化反応により得られた反応液に水を添加し、攪拌及び混合する方法等が挙げられる。
　水としては、純水を使用することが好ましい。 ● Before carrying out the pretreatment neutralization treatment, the reaction solution can be washed with water for various purposes.
In particular, when a copper polymerization inhibitor is used in the esterification reaction, the copper polymerization inhibitor can be efficiently removed, which is preferable.
As a method for the water washing treatment, a conventional method may be followed. Specifically, a method of adding water to the reaction solution obtained by the esterification reaction, stirring and mixing, and the like may be mentioned.
As water, it is preferable to use pure water.
●アクリレート最終製品
　第２工程では、前記中和処理後に、有機相と水相の２相に分離させ、有機相を分取し、アクリレートを回収する。
　有機相の分取の方法としては、下層である水相を抜き出せば良い。抜き出した水相は、後記する第３工程を実施する。
　前記で水相を分取した後の有機層は、必要に応じて、有機溶媒を除去し最終製品のアクリレートとすることができる。
　脱溶剤処理は、常法に従えば良く、例えば脱溶剤槽を減圧にし、有機溶媒を除去する方法等が挙げられる。脱溶剤槽の真空度としては、使用する原料及び目的に応じて適宜設定すれば良く、好ましくは０．５～５０ｋＰａであり、溶剤の除去程度により徐々に減圧度を増す方法が好ましい。 In the second step of the final acrylate product , after the neutralization treatment, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered.
As a method for separating the organic phase, the lower aqueous phase may be extracted. The extracted aqueous phase is subjected to a third step which will be described later.
In the organic layer after separating the aqueous phase as described above, the organic solvent can be removed to make the acrylate of the final product, if necessary.
The solvent removal treatment may be carried out in accordance with a conventional method, for example, a method in which the solvent removal tank is decompressed and the organic solvent is removed. The degree of vacuum in the solvent removal tank may be appropriately set according to the raw material to be used and the purpose, and is preferably 0.5 to 50 kPa, and a method of gradually increasing the degree of vacuum depending on the degree of solvent removal is preferable.
　この脱溶剤処理は、アクリレートの熱重合を抑えるために、酸素を供給したり、重合禁止剤を添加したりするとともに、温度を例えば２０℃以上８０℃以下に維持して、減圧下に行うことが好ましい。
　必要に応じて、前記脱溶剤処理において有機相から有機溶媒を脱溶剤槽で除去するとともに、脱溶剤槽へ濾過助剤を供給し、脱溶剤槽に接続された竪型水平濾板式の濾過器に濾過助剤を堆積させて反応生成物の濾過処理を行うこともできる。 In order to suppress thermal polymerization of acrylate, this solvent removal treatment is performed under reduced pressure while supplying oxygen or adding a polymerization inhibitor and maintaining the temperature at, for example, 20 ° C. or more and 80 ° C. or less. Is preferred.
If necessary, the organic solvent is removed from the organic phase in the solvent removal process in the solvent removal tank, a filter aid is supplied to the solvent removal tank, and the vertical horizontal filter type filter connected to the solvent removal tank is used. The reaction product can also be filtered by depositing a filter aid.
　また、有機層は、必要に応じて脱溶剤処理を行う前に、水洗処理を行うこともできる。 Further, the organic layer can be washed with water before the solvent removal treatment as necessary.
３）第３工程
　第３工程は、第２工程で得られた水相を分取し〔以下、水相（２）という。〕、これに硫酸濃度７０重量％以上の硫酸水溶液を添加し、ｐＨを４．０以下に調整し、かつ液中のアクリル酸及び／又はそのアルカリ金属塩の含有割合をアクリル酸換算で１８重量％以上とする工程である。 3) Third Step The third step fractionates the aqueous phase obtained in the second step [hereinafter referred to as the aqueous phase (2). ] A sulfuric acid aqueous solution having a sulfuric acid concentration of 70% by weight or more was added thereto, the pH was adjusted to 4.0 or lower, and the acrylic acid and / or its alkali metal salt content in the liquid was 18% in terms of acrylic acid. % Or more.
　第３工程で使用する硫酸水溶液の硫酸濃度は、７０重量％以上である。７０重量％未満のものを使用する場合、第４工程の２相分離が困難となり、アクリル酸（塩）の回収率が低下してしまう。硫酸水溶液の硫酸濃度としては、７５重量％以上が好ましく、また、１００重量％以下であることが好ましく、９９重量％以下であることがより好ましい。 The sulfuric acid concentration of the sulfuric acid aqueous solution used in the third step is 70% by weight or more. When less than 70% by weight is used, two-phase separation in the fourth step becomes difficult, and the recovery rate of acrylic acid (salt) decreases. The sulfuric acid concentration of the aqueous sulfuric acid solution is preferably 75% by weight or more, preferably 100% by weight or less, and more preferably 99% by weight or less.
　第３工程では、水相（２）に硫酸水溶液を添加して、ｐＨを４．０以下とする。ｐＨが４．０を超過する場合は、第４工程の２相分離が困難となり、アクリル酸（塩）の回収率が低下してしまう。好ましい水相のｐＨとしては、０～４．０の範囲であり、より好ましくは１～３．５の範囲である。
　水相（２）に添加する硫酸水溶液の添加量としては、水相のｐＨが４．０以下となる量であれば任意である。 In the third step, an aqueous sulfuric acid solution is added to the aqueous phase (2) to adjust the pH to 4.0 or less. When the pH exceeds 4.0, two-phase separation in the fourth step becomes difficult, and the recovery rate of acrylic acid (salt) is lowered. The pH of the preferred aqueous phase is in the range of 0 to 4.0, more preferably in the range of 1 to 3.5.
The amount of the sulfuric acid aqueous solution added to the aqueous phase (2) is arbitrary as long as the pH of the aqueous phase is 4.0 or less.
　水相（２）に硫酸水溶液を添加する場合における温度としては、２５℃以上が好ましく、より好ましくは２５～４０℃であり、特に好ましくは３０～４０℃である。この温度を２５℃以上とすることにより、第３工程において硫酸塩が析出することを防止することができる。 When the aqueous sulfuric acid solution is added to the aqueous phase (2), the temperature is preferably 25 ° C. or more, more preferably 25 to 40 ° C., and particularly preferably 30 to 40 ° C. By setting this temperature to 25 ° C. or higher, it is possible to prevent the sulfate from being precipitated in the third step.
　本発明のアクリレートの製造方法では、第３工程において、液中のアクリル酸及び／又はそのアルカリ金属塩〔以下、「アクリル酸（塩）」という。〕の含有割合をアクリル酸換算で１８重量％以上とし、６０重量％以下が好ましい。また、前記含有割合は、２０重量％以上が好ましく、特に好ましくは２０～６０重量％である。この割合が１８重量％より低いと、第４工程において２相分離させることができない。
　液中のアクリル酸（塩）の含有割合をアクリル酸換算で１８重量％以上とする方法としては、第２工程で使用するアルカリ水溶液の濃度及びアルカリ水溶液の使用量を調整する方法等が挙げられる。また、液中のアクリル酸（塩）の含有割合が１８重量％に満たない場合は、水を留去、又は、アクリル酸（塩）を追加して、アクリル酸（塩）の含有割合が前記割合となるようにすることもできる。
　尚、液中のアクリル酸（塩）の割合は、液体クロマトグラフィ、ガスクロマトグラフィ及びイオンクロマトグラフィ等の方法で測定することができる。この場合、事前にアクリル酸（塩）を使用して検量線を作成しておき、測定した値を絶対検量線法により補正して割合を決定することができる。アクリル酸塩として測定した場合には、計算によりアクリル酸に換算する。 In the acrylate production method of the present invention, in the third step, acrylic acid and / or an alkali metal salt thereof in the liquid [hereinafter referred to as “acrylic acid (salt)”]. ] Is 18% by weight or more and preferably 60% by weight or less in terms of acrylic acid. The content is preferably 20% by weight or more, particularly preferably 20 to 60% by weight. If this proportion is lower than 18% by weight, two-phase separation cannot be performed in the fourth step.
Examples of the method for setting the content ratio of acrylic acid (salt) in the liquid to 18% by weight or more in terms of acrylic acid include a method of adjusting the concentration of the aqueous alkali solution used in the second step and the amount of the aqueous alkali solution used. . Moreover, when the content rate of acrylic acid (salt) in a liquid is less than 18 weight%, water is distilled off or acrylic acid (salt) is added, and the content rate of acrylic acid (salt) is the said. It can also be a percentage.
The ratio of acrylic acid (salt) in the liquid can be measured by methods such as liquid chromatography, gas chromatography, and ion chromatography. In this case, a calibration curve is prepared in advance using acrylic acid (salt), and the ratio can be determined by correcting the measured value by the absolute calibration curve method. When measured as an acrylate, it is converted to acrylic acid by calculation.
　尚、特許文献１（特開２００６－２１３６４７号公報）において、実施例に記載された水相中のアクリル酸濃度は１６．６重量％であり、特許文献２（特開昭６１－２４３０４６号公報）において、実施例３に記載された水相中のアクリル酸濃度は１５．５重量％であり、いずれも２相分離しているものでなかった。
　本発明者らは、前記公知文献で全く開示されていない、液中のアクリル酸（塩）濃度を特定値とすることで、前記公知文献で全く示唆も開示もされていない、後記第４工程における２相分離を達成できることを見出したのである。 In Patent Document 1 (Japanese Patent Laid-Open No. 2006-213647), the acrylic acid concentration in the aqueous phase described in the examples is 16.6% by weight, and Patent Document 2 (Japanese Patent Laid-Open No. 61-243046). ), The acrylic acid concentration in the aqueous phase described in Example 3 was 15.5 wt%, and none of them was separated into two phases.
The inventors of the present invention have not disclosed or disclosed in the above-mentioned known literature at all by setting the acrylic acid (salt) concentration in the liquid to a specific value, which is not disclosed in the above-mentioned known literature. It has been found that two-phase separation can be achieved.
４）第４工程
　第４工程は、第３工程で得られた液を、アクリル酸（塩）を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程である。 4) Fourth step In the fourth step, the liquid obtained in the third step is separated into two phases: a phase containing a large amount of acrylic acid (salt) (upper layer) and a phase containing a large amount of alkali metal sulfate (lower layer). It is a process to do.
　この場合の温度としては、２５～４０℃が好ましく、３０～４０℃がより好ましい。この温度範囲に維持とすることにより、硫酸塩の析出を防止ができる。 In this case, the temperature is preferably 25 to 40 ° C, more preferably 30 to 40 ° C. By maintaining in this temperature range, precipitation of sulfate can be prevented.
　この工程において、アクリル酸（塩）を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する方法としては、特に限定されるものではないが、比重差を利用する方法が好ましく、静置分離する方法、遠心分離による方法等が挙げられる。
　静置分離する場合は、第３工程で得られた液を前記した好ましい温度で一定時間静置することで良い。 In this step, the method of separating into two phases of a phase (upper layer) rich in acrylic acid (salt) and a phase (lower layer) rich in alkali metal sulfate is not particularly limited, but the specific gravity difference Are preferably used, and examples thereof include a stationary separation method and a centrifugation method.
When standing and separating, the liquid obtained in the third step may be allowed to stand at the above-mentioned preferable temperature for a certain period of time.
５）第５工程
　第５工程は、第４工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸（塩）を多く含む相（上層）を回収する工程である。 5) Fifth step Fifth step is to separate a phase (lower layer) containing a large amount of alkali metal sulfate of the liquid obtained in the fourth step, and a remaining phase (upper layer) containing a large amount of acrylic acid (salt). It is a process to collect.
　第４工程により、アクリル酸（塩）を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離させる。
　その後、第５工程で、下層の硫酸アルカリ金属塩を多く含む相を処理槽下部から抜き出すことにより、アクリル酸（塩）を多く含む相を回収することができる。 By a 4th process, it is made to isolate | separate into two phases of the phase (upper layer) which contains many acrylic acids (salt), and the phase (lower layer) which contains many sulfated alkali metal salts.
Thereafter, in the fifth step, the phase containing a large amount of the lower layer of alkali metal sulfate is extracted from the lower part of the treatment tank, whereby the phase containing a large amount of acrylic acid (salt) can be recovered.
　回収された相中のアクリル酸（塩）の割合は、使用する原料や条件により異なるが、２５～６０重量％のアクリル酸（塩）を含む水溶液が好適に得られる。 The ratio of acrylic acid (salt) in the recovered phase varies depending on the raw materials and conditions used, but an aqueous solution containing 25 to 60% by weight of acrylic acid (salt) is preferably obtained.
●アクリル酸（塩）の再利用
　回収されたアクリル酸（塩）水溶液は、処理条件により変動するが、アクリル酸を主成分とし、アクリル酸のアルカリ金属塩をわずかに含む水溶液として得られる。回収されたアクリル酸（塩）水溶液はそのまま使用することもでき、また、精製して使用することもでき、さらにアクリル酸を分離して使用することもできる。 Recycling of acrylic acid (salt) The recovered aqueous solution of acrylic acid (salt) varies depending on the processing conditions, but is obtained as an aqueous solution containing acrylic acid as a main component and slightly containing an alkali metal salt of acrylic acid. The recovered aqueous solution of acrylic acid (salt) can be used as it is, or it can be purified and used, and acrylic acid can be separated and used.
　回収されたアクリル酸（塩）水溶液は、目的とする用途によっては精製することなくそのまま重合することにより、ポリアクリル酸やポリアクリル酸塩の製造に好適に使用することができる。
　得られたポリアクリル酸やポリアクリル酸塩（好ましくはナトリウム塩）は、分散剤、増粘剤及び凝集剤等の用途に好適に使用することができる。
　尚、純度が要求される用途の場合には、前記重合に先立ってアクリル酸（塩）水溶液の精製を行い、精製後のアクリル酸（塩）水溶液を使用して重合に使用することができる。 The recovered aqueous solution of acrylic acid (salt) can be suitably used for the production of polyacrylic acid or polyacrylate by polymerizing as it is without purification depending on the intended use.
The obtained polyacrylic acid and polyacrylic acid salt (preferably sodium salt) can be suitably used for applications such as a dispersant, a thickener and a flocculant.
In applications where purity is required, the acrylic acid (salt) aqueous solution can be purified prior to the polymerization, and the purified acrylic acid (salt) aqueous solution can be used for the polymerization.
　回収されたアクリル酸（塩）水溶液からアクリル酸を分離して使用する場合は、回収されたアクリル酸（塩）水溶液にトルエン等の有機溶媒を添加し、加熱して水を共沸留去する方法が挙げられる。
　得られたアクリル酸は、ポリマー及びアクリレートの製造原料として使用することができる。又、第一工程における原料アクリル酸としても使用することができる。 When separating and using acrylic acid from the recovered aqueous solution of acrylic acid (salt), an organic solvent such as toluene is added to the recovered aqueous solution of acrylic acid (salt) and heated to distill off water azeotropically. A method is mentioned.
The obtained acrylic acid can be used as a raw material for producing polymers and acrylates. It can also be used as a raw material acrylic acid in the first step.
●下層の廃棄・処理
　下層として処理槽から抜き出した硫酸アルカリ金属塩を多く含む相の処理方法としては特に限定されるものではないが、そのまま燃焼処理することができる。又、該溶液を冷却し、硫酸アルカリ金属塩を結晶として分離することもできる。
　又、水を留去した後、析出した硫酸塩を分離することにより、アクリル酸（塩）水溶液として回収することも可能である。 ● Disposal / treatment of the lower layer The treatment method for the phase containing a large amount of alkali metal sulfate extracted from the treatment tank as the lower layer is not particularly limited, but can be subjected to combustion treatment as it is. In addition, the solution can be cooled to separate the alkali metal sulfate as crystals.
It is also possible to recover the aqueous solution of acrylic acid (salt) by distilling off the water and then separating the precipitated sulfate.
２．アクリル酸の回収方法
　本発明のアクリル酸の回収方法は、下記第３’工程～第５’工程を順次実施することを特徴とするに関する。
第３’工程：アクリル酸及び／又はそのアルカリ金属塩、硫酸アルカリ金属塩、並びに、水を含有し、ｐＨが４．０以下であり、かつアクリル酸及び／又はそのアルカリ金属塩の含有割合がアクリル酸換算で１８重量％以上である液を調製する工程
第４’工程：第３’工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
第５’工程：第４’工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程 2. Acrylic acid recovery method The acrylic acid recovery method of the present invention is characterized by sequentially performing the following third to fifth steps.
3 'process: It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step: The liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid. Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step: The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
１）第３’工程
　第３’工程は、アクリル酸及び／又はそのアルカリ金属塩、硫酸アルカリ金属塩、並びに、水を含有し、ｐＨが４．０以下であり、かつアクリル酸及び／又はそのアルカリ金属塩の含有割合がアクリル酸換算で１８重量％以上である液を調製する工程である。 1) Step 3 ′ Step 3 ′ contains acrylic acid and / or its alkali metal salt, alkali metal sulfate salt, and water, has a pH of 4.0 or less, and acrylic acid and / or its This is a step of preparing a liquid having an alkali metal salt content of 18% by weight or more in terms of acrylic acid.
　第３’工程で得られる液のｐＨは、４．０以下の範囲であり、０～４．０の範囲であることが好ましく、１～３．５の範囲であることがより好ましい。ｐＨが４．０を超過する場合は、第４工程の２相分離が困難となり、アクリル酸（塩）の回収率が低下してしまう。
　第３’工程で得られる液中のアクリル酸及び／又はそのアルカリ金属塩の含有割合は、アクリル酸換算で１８重量％以上であり、６０重量％以下が好ましい。また、前記含有割合は、２０重量％以上が好ましく、２０～６０重量％が特に好ましい。前記含有割合が１８重量％より低いと、第４’工程において２相分離させることができない。
　第３’工程で得られる液中において、アクリル酸のアルカリ金属塩及び硫酸アルカリ金属塩のアルカリ金属塩としては、特に制限はないが、ナトリウム塩、及び、カリウム塩が好ましく挙げられ、ナトリウム塩がより好ましく挙げられる。
　また、第３’工程で得られる液は、前記本発明のアクリレートの製造方法における第１工程から第３工程を経て得られる液であることが好ましい。
　更に、第３’工程における液の温度としては、２５℃以上が好ましく、２５～４０℃がより好ましく、３０～４０℃が特に好ましい。液の温度を２５℃以上とすることにより、第３’工程において硫酸塩が析出することを防止することができる。 The pH of the liquid obtained in the third 3 ′ step is in the range of 4.0 or less, preferably in the range of 0 to 4.0, and more preferably in the range of 1 to 3.5. When the pH exceeds 4.0, two-phase separation in the fourth step becomes difficult, and the recovery rate of acrylic acid (salt) is lowered.
The content ratio of acrylic acid and / or its alkali metal salt in the liquid obtained in the third step is 18% by weight or more and preferably 60% by weight or less in terms of acrylic acid. The content is preferably 20% by weight or more, particularly preferably 20 to 60% by weight. If the content is less than 18% by weight, two-phase separation cannot be performed in the 4 ′ step.
In the liquid obtained in the 3 ′ step, the alkali metal salt of acrylic acid and the alkali metal sulfate alkali metal salt are not particularly limited, but sodium salt and potassium salt are preferably mentioned, and the sodium salt is More preferably.
Moreover, it is preferable that the liquid obtained by a 3 'process is a liquid obtained through the 3rd process from the 1st process in the manufacturing method of the acrylate of the said invention.
Furthermore, the temperature of the liquid in the 3 ′ step is preferably 25 ° C. or higher, more preferably 25 to 40 ° C., and particularly preferably 30 to 40 ° C. By setting the temperature of the liquid to 25 ° C. or higher, it is possible to prevent the sulfate from being precipitated in the third ′ step.
２）第４’工程
　第４’工程は、第３’工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程である。
　第４’工程は、第３工程で得られた液の代わりに第３’工程で得られた液を使用する以外は、第４工程と同義であり、好ましい態様も同様である。 2) Step 4 'Step 4' step is a step in which the liquid obtained in step 3 'is a phase (upper layer) containing a large amount of acrylic acid and / or an alkali metal salt thereof and a phase containing a large amount of an alkali metal sulfate ( It is a step of separating into two phases of the lower layer.
4th process is synonymous with 4th process except using the liquid obtained at 3 'process instead of the liquid obtained at 3rd process, and its preferable aspect is also the same.
３）第５’工程
　第５’工程は、第４’工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程である。
　第５’工程は、第４工程で得られた液の代わりに第４’工程で得られた液を使用する以外は、第５工程と同義であり、好ましい態様も同様である。 3) Step 5 'Step 5' step is to separate a phase (lower layer) containing a large amount of alkali metal sulfate in the liquid obtained in step 4 ', and to leave the remaining acrylic acid and / or alkali metal salt thereof. This is a step of recovering a phase (upper layer) containing a large amount.
5th process is synonymous with 5th process except using the liquid obtained at 4 'process instead of the liquid obtained at 4th process, and its preferable aspect is also the same.
　本発明のアクリル酸の回収方法により回収されたアクリル酸（塩）水溶液は、処理条件により変動するが、アクリル酸を主成分とし、アクリル酸のアルカリ金属塩をわずかに含む水溶液として得られる。回収されたアクリル酸（塩）水溶液はそのまま使用することもでき、また、精製して使用することもでき、さらにアクリル酸を分離して使用することもできる。
　また、本発明のアクリル酸の回収方法により回収されたアクリル酸（塩）水溶液から、公知の方法により、アクリル酸及び／又はそのアルカリ金属塩を単離及び／又は精製してもよい。
　また、前記アクリル酸（塩）の再利用にて述べたように、回収されたアクリル酸（塩）水溶液は、目的とする用途によっては精製することなくそのまま重合することにより、ポリアクリル酸やポリアクリル酸塩の製造に好適に使用することができる。 The acrylic acid (salt) aqueous solution recovered by the acrylic acid recovery method of the present invention varies depending on the processing conditions, but is obtained as an aqueous solution containing acrylic acid as a main component and slightly containing an alkali metal salt of acrylic acid. The recovered aqueous solution of acrylic acid (salt) can be used as it is, or it can be purified and used, and acrylic acid can be separated and used.
In addition, acrylic acid and / or an alkali metal salt thereof may be isolated and / or purified from an aqueous solution of acrylic acid (salt) recovered by the acrylic acid recovery method of the present invention by a known method.
Further, as described in the reuse of acrylic acid (salt), the recovered aqueous solution of acrylic acid (salt) is polymerized as it is without purification depending on the intended use, so that polyacrylic acid or polyacrylic acid can be obtained. It can be suitably used for the production of acrylates.
　以下に、実施例及び比較例を挙げて、本発明をより具体的に説明する。尚、以下において、「％」は重量％を意味する。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following, “%” means% by weight.
（実施例１）
　アクリル酸３，０００ｇ、ジペンタエリスリトール（以下、「ＤＰＥＴ」という。）１，４７０ｇ、７８％硫酸７０ｇ、ハイドロキノン（以下、「ＨＱ」という。）１０ｇ及びトルエン２，４５０ｇを１０Ｌ反応釜に仕込み、５３ｋＰａの圧力下、１００℃に設定したオイルバス中で加熱し、縮合水をトルエンとの共沸水として除去しながら、１０時間反応させた。このときの反応液重量は６，２５０ｇであった。
　反応終了後に、トルエン３，５００ｇを追加した。次いで、純水３２５ｇを加えて攪拌した後、静置し、上層（有機相）と下層（水相）に分離した。反応釜から下層（水相）を抜き出し、上層（有機相）を回収した。 Example 1
3,000 g of acrylic acid, 1,470 g of dipentaerythritol (hereinafter referred to as “DPET”), 70 g of 78% sulfuric acid, 10 g of hydroquinone (hereinafter referred to as “HQ”) and 2,450 g of toluene were charged into a 10 L reaction kettle. It heated in the oil bath set to 100 degreeC under the pressure of 53 kPa, and it was made to react for 10 hours, removing condensed water as azeotropic water with toluene. The reaction liquid weight at this time was 6,250 g.
After completion of the reaction, 3,500 g of toluene was added. Next, after adding 325 g of pure water and stirring, the mixture was allowed to stand and separated into an upper layer (organic phase) and a lower layer (aqueous phase). The lower layer (aqueous phase) was extracted from the reaction kettle, and the upper layer (organic phase) was recovered.
　この上層（有機相）に、２０％水酸化ナトリウム水溶液１，７００ｇを加えて攪拌した後、静置し、９，０００ｇの上層（有機相）と２，４００ｇの下層（水相）を得た。
　反応釜からこの下層（水相）（以下、「中和廃水」という。）を抜き出した。なお、当該中和廃水は、以下に示す実施例２及び３、並びに、比較例１において使用した。
　得られた中和廃水を、液体クロマトグラフィ〔（株）島津製作所製、製品名ＬＣ－１０Ａ〕を使用して、絶対検量線法にて分析したところ、アクリル酸ナトリウムが３２．２％（アクリル酸として、２４．７％）含有されていた。 To this upper layer (organic phase), 1,700 g of a 20% aqueous sodium hydroxide solution was added and stirred, and then allowed to stand to obtain 9,000 g of the upper layer (organic phase) and 2,400 g of the lower layer (aqueous phase). .
This lower layer (aqueous phase) (hereinafter referred to as “neutralized wastewater”) was extracted from the reaction kettle. The neutralized wastewater was used in Examples 2 and 3 and Comparative Example 1 shown below.
The obtained neutralized wastewater was analyzed by an absolute calibration curve method using liquid chromatography [manufactured by Shimadzu Corporation, product name LC-10A]. As a result, sodium acrylate was found to be 32.2% (acrylic acid As 24.7%).
　尚、上層（有機相）については、更に２０％水酸化ナトリウム水溶液１，３６０ｇ加えて攪拌した後、静置し、上層（有機相）と下層（水相）に分離した。この上層（有機相）に、純水４００ｇを加えて攪拌した後、静置し、８，６６０ｇの上層（有機相）と下層（水相）に分離した。得られた上層（有機相）にハイドロキノンモノメチルエーテル（以下、「ＭＱ」という。）を１．３ｇ添加し、減圧下にトルエンを留去して、２，７５０ｇのアクリレート（ジペンタエリスリトールペンタアクリレートとヘキサアクリレートとの混合物）を得た。 The upper layer (organic phase) was further added with 1,360 g of a 20% aqueous sodium hydroxide solution, stirred, allowed to stand, and separated into an upper layer (organic phase) and a lower layer (aqueous phase). To this upper layer (organic phase), 400 g of pure water was added and stirred, then allowed to stand, and separated into an upper layer (organic phase) and a lower layer (aqueous phase) of 8,660 g. To the obtained upper layer (organic phase), 1.3 g of hydroquinone monomethyl ether (hereinafter referred to as “MQ”) was added, toluene was distilled off under reduced pressure, and 2,750 g of acrylate (dipentaerythritol pentaacrylate and A mixture with hexaacrylate) was obtained.
　上記で得られた中和廃水３００ｇに、９８％硫酸をｐＨ３になるまで徐々に加えた。添加した９８％硫酸は４６．９ｇであった。なお、硫酸添加時の液の温度は２５～３０℃に維持した。
　次いで、液温が３０～３５℃になるように保温し、静置して、上層（アクリル酸水溶液層）と下層（硫酸ナトリウム水溶液層）に分離した。
　２相に分離した液を分液ロートに移し、下層（硫酸ナトリウム水溶液層）を抜き出した。
　得られた上層のアクリル酸水溶液層は１４６．５ｇ、アクリル酸濃度は４０．６％であり、中和廃水に含まれていたアクリル酸に対して８０．４％のアクリル酸を回収することができた。 To 300 g of the neutralized wastewater obtained above, 98% sulfuric acid was gradually added until the pH reached 3. The added 98% sulfuric acid was 46.9 g. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C.
Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer).
The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted.
The obtained upper acrylic acid aqueous solution layer was 146.5 g, the acrylic acid concentration was 40.6%, and 80.4% of acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. did it.
　尚、下層の硫酸ナトリウム水溶液については、約１０℃まで冷却し、析出した結晶を固液分離した結果、硫酸ナトリウム３７．７％を含有する結晶１２２．１ｇとアクリル酸１３．５％、硫酸ナトリウム５．７％を含有する水溶液６３．２ｇが得られた。 In addition, about the lower layer sodium sulfate aqueous solution, as a result of cooling to about 10 degreeC and carrying out solid-liquid separation of the precipitated crystal | crystallization, 122.1g of crystals containing 37.7% of sodium sulfate, acrylic acid 13.5%, sodium sulfate 63.2 g of an aqueous solution containing 5.7% was obtained.
（実施例２）
　実施例１で得られた中和廃水３００ｇに７８％硫酸をｐＨ３になるまで徐々に加えた。なお、硫酸添加時の液の温度は２５～３０℃に維持した。また、添加した７８％硫酸は５９．０ｇであった。
　次いで、液温が３０～３５℃になるように保温し、静置して、上層（アクリル酸水溶液層）と下層（硫酸ナトリウム水溶液層）に分離した。
　２相に分離した液を分液ロートに移し、下層（硫酸ナトリウム水溶液層）を抜き出した。
　得られた上層のアクリル酸水溶液層は１５１．８ｇ、アクリル酸濃度は３７．４％であり、中和廃水に含まれていたアクリル酸に対して７６．７％のアクリル酸を回収することができた。 (Example 2)
To 300 g of the neutralized wastewater obtained in Example 1, 78% sulfuric acid was gradually added until the pH reached 3. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The added 78% sulfuric acid was 59.0 g.
Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer).
The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted.
The obtained upper acrylic acid aqueous solution layer was 151.8 g, the acrylic acid concentration was 37.4%, and 76.7% acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. did it.
（実施例３）
　実施例１で得られた中和廃水３００ｇに９８％硫酸をｐＨ２になるまで徐々に加えた。なお、硫酸添加時の液の温度は２５～３０℃に維持した。また、添加した９８％硫酸は５２．１ｇであった。
　次いで、液温が３０～３５℃になるように保温し、静置して、上層（アクリル酸水溶液層）と下層（硫酸ナトリウム水溶液層）に分離した。
　２相に分離した液を分液ロートに移し、下層（硫酸ナトリウム水溶液層）を抜き出した。
　得られた上層のアクリル酸水溶液層は１２８．４ｇ、アクリル酸濃度は４４．６％となり、中和廃水に含まれていたアクリル酸に対して７７．４％のアクリル酸を回収することができた。 (Example 3)
To 300 g of the neutralized wastewater obtained in Example 1, 98% sulfuric acid was gradually added until pH 2 was reached. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The added 98% sulfuric acid was 52.1 g.
Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer).
The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted.
The obtained upper acrylic acid aqueous solution layer was 128.4 g, the acrylic acid concentration was 44.6%, and 77.4% of acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. It was.
（比較例１）
　実施例１で得られた中和廃水３００ｇに９８％硫酸をｐＨ４．２になるまで徐々に加えた。なお、硫酸添加時の液の温度は２５～３０℃に維持した。また、添加した９８％硫酸は３２ｇであった。
　次いで、液温が３０～３５℃になるように保温したが、２相に分離しなかったためアクリル酸を分離回収することはできなかった。 (Comparative Example 1)
98% sulfuric acid was gradually added to 300 g of the neutralized wastewater obtained in Example 1 until the pH reached 4.2. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The 98% sulfuric acid added was 32 g.
Next, the liquid temperature was kept at 30 to 35 ° C. However, acrylic acid could not be separated and recovered because it was not separated into two phases.
（比較例２）
　特許文献１における実施例１の追試を実施した。
　即ち、アクリル酸２，０００ｇ、ＤＰＥＴ１，２００ｇ、７８％硫酸５０ｇ、ＨＱ１０ｇ、トルエン２，４５０ｇを１０Ｌフラスコに仕込み、６０ｋＰａの圧力下、１２０℃に設定したオイルバス中で加熱し、縮合水をトルエンとの共沸水として除去しながら、１０時間反応させた。このときの反応液重量は６，９００ｇであった。 (Comparative Example 2)
The supplementary examination of Example 1 in patent document 1 was implemented.
That is, 2,000 g of acrylic acid, 1,200 g of DPET, 50 g of 78% sulfuric acid, 10 g of HQ, and 2,450 g of toluene were charged into a 10 L flask, heated in an oil bath set at 120 ° C. under a pressure of 60 kPa, and condensed water was added to toluene. The mixture was reacted for 10 hours while removing as azeotropic water. The reaction liquid weight at this time was 6,900 g.
　得られた反応液に、２０％水酸化ナトリウム水溶液２，６５０ｇを加えて攪拌した後、静置し、６，２５０ｇの上層（有機相）と３，０００ｇの下層（水相）を得た。
　フラスコからこの下層（水相）を抜き出し、中和廃水として、以下に示すアクリル酸回収試験を行った。
　得られた中和廃水を、液体クロマトグラフィを使用して実施例と同様に分析したところ、アクリル酸ナトリウムを２１．７％（アクリル酸として、１６．６％）含むものであった。 To the resulting reaction solution, 2,650 g of 20% aqueous sodium hydroxide solution was added and stirred, and then allowed to stand to obtain 6,250 g of an upper layer (organic phase) and 3,000 g of a lower layer (aqueous phase).
The lower layer (aqueous phase) was extracted from the flask, and the acrylic acid recovery test shown below was conducted as neutralized wastewater.
The obtained neutralized wastewater was analyzed in the same manner as in Example using liquid chromatography. As a result, it contained 21.7% sodium acrylate (16.6% as acrylic acid).
　これから先の操作は、特許文献１の実施例に記載された１／１０スケールで実施した。
　得られた中和廃水３００ｇに、９８％硫酸をｐＨ１．８になるまで徐々に加えた。なお、硫酸添加時の液の温度は２５～３０℃に維持した。また、添加した９８％硫酸は３６ｇであった。次いで、液温が３０～３５℃になるように保温したが、２相に分離しなかったためアクリル酸を分離回収することはできなかった。 From now on, the operation was performed on the 1/10 scale described in the example of Patent Document 1.
To 300 g of the neutralized wastewater obtained, 98% sulfuric acid was gradually added until the pH reached 1.8. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The added 98% sulfuric acid was 36 g. Next, the liquid temperature was kept at 30 to 35 ° C. However, acrylic acid could not be separated and recovered because it was not separated into two phases.
（実施例４）
　アクリル酸３，０００ｇ、ペンタエリスリトール１，６００ｇ、７８％硫酸７０ｇ、ＭＱ７ｇ、トルエン２，０００ｇを１０Ｌ反応釜に仕込み、５０ｋＰａの圧力下、１００℃に設定したオイルバス中で加熱し、縮合水を除去しながら、６時間反応させた。このときの反応液重量は６，１００ｇであった。
　反応終了後に、トルエン３，５００ｇを追加した。 Example 4
3,000 g of acrylic acid, 1,600 g of pentaerythritol, 70 g of 78% sulfuric acid, MQ 7 g, and 2,000 g of toluene are charged into a 10 L reaction kettle, heated in an oil bath set at 100 ° C. under a pressure of 50 kPa, and condensed water is added. The reaction was allowed to proceed for 6 hours while removing. The reaction solution weight at this time was 6,100 g.
After completion of the reaction, 3,500 g of toluene was added.
　次いで２０％水酸化ナトリウム水溶液を２，９５０ｇ添加して撹拌した後、静置して上層（有機相）７，６５０ｇ及び下層（水相）４，９００ｇに分離した。
　反応釜から下層（水相）を抜き出し、中和廃水として得た。
　得られた中和廃水の組成を実施例１と同様に分析した結果、アクリル酸ナトリウムが２９．１％（アクリル酸として、２２．３％）含有されていた。 Next, 2,950 g of 20% aqueous sodium hydroxide solution was added and stirred, and then allowed to stand to separate into 7,650 g of the upper layer (organic phase) and 4,900 g of the lower layer (aqueous phase).
The lower layer (aqueous phase) was extracted from the reaction kettle and obtained as neutralized waste water.
As a result of analyzing the composition of the obtained neutralized wastewater in the same manner as in Example 1, 29.1% sodium acrylate (22.3% as acrylic acid) was contained.
　尚、上層（有機相）については、純水１，０００ｇを加えて攪拌した後、静置し、７，６５０ｇの上層（有機相）と下層（水相）に分離した。得られた上層（有機相）はトルエンを留去して、２，１５０ｇのアクリレート（ジペンタエリスリトールペンタアクリレートとヘキサアクリレートとの混合物）を得た。 In addition, about the upper layer (organic phase), after adding 1,000 g of pure water and stirring, it stood still and isolate | separated into the upper layer (organic phase) and lower layer (aqueous phase) of 7,650 g. Toluene was distilled off from the obtained upper layer (organic phase) to obtain 2,150 g of acrylate (a mixture of dipentaerythritol pentaacrylate and hexaacrylate).
　上記で得られた中和廃水４５０ｇに９８％硫酸をｐＨ３になるまで徐々に加えた。なお、硫酸添加時の液の温度は２５～３０℃に維持した。また、添加した９８％硫酸は６４．３ｇであった。
　次いで、液温が３０～３５℃になるように保温し、静置して、上層（アクリル酸水溶液層）と下層（硫酸ナトリウム水溶液層）に分離した。
　２相に分離した液を分液ロートに移し、下層（硫酸ナトリウム水溶液層）を抜き出した。
　得られた上層のアクリル酸水溶液層は２５０．１ｇ、アクリル酸濃度は３１．０％であり、中和廃水に含まれていたアクリル酸に対して７４．２％のアクリル酸を回収することができた。 To 450 g of the neutralized waste water obtained above, 98% sulfuric acid was gradually added until the pH reached 3. The temperature of the liquid at the time of adding sulfuric acid was maintained at 25-30 ° C. The 98% sulfuric acid added was 64.3 g.
Next, the solution was kept at a temperature of 30 to 35 ° C., allowed to stand, and separated into an upper layer (acrylic acid aqueous solution layer) and a lower layer (sodium sulfate aqueous solution layer).
The liquid separated into two phases was transferred to a separating funnel, and the lower layer (sodium sulfate aqueous solution layer) was extracted.
The obtained upper acrylic acid aqueous solution layer was 250.1 g, the acrylic acid concentration was 31.0%, and 74.2% of acrylic acid was recovered with respect to the acrylic acid contained in the neutralized wastewater. did it.
　尚、下層の硫酸ナトリウム水溶液については、約１０℃まで冷却し、析出した結晶を固液分離した結果、硫酸ナトリウム３６．８％を含有する結晶２２８．７ｇとアクリル酸１６．８％、硫酸ナトリウム６．６％を含有する水溶液６７．０ｇが得られた。 In addition, about the lower layer sodium sulfate aqueous solution, it cooled to about 10 degreeC, and as a result of carrying out solid-liquid separation of the precipitated crystal | crystallization, 228.7g of crystals containing 36.8% of sodium sulfate, acrylic acid 16.8%, sodium sulfate 67.0 g of an aqueous solution containing 6.6% was obtained.
（応用例）
　反応釜にイオン交換水４０ｇを仕込み、窒素シールしながら８０℃まで昇温後、１０％過硫酸ナトリウム水溶液１ｇを添加した。続いて、実施例２で回収したアクリル酸水溶液２１０ｇに次亜リン酸ナトリウム５ｇを溶解したモノマー溶液と１０％過硫酸ナトリウム水溶液１０ｇを、重合温度８０℃を維持しながら、別々の注入口より反応器に４時間連続的に滴下し、ポリアクリル酸水溶液を得た。
　このポリアクリル酸水溶液を４８％水酸化ナトリウムにてｐＨ＝７．５に中和し、
　固形分４１．９重量％、粘度２６４ｍＰａ・ｓのポリアクリル酸ナトリウム水溶液が得られた。 (Application examples)
The reaction kettle was charged with 40 g of ion exchange water, heated to 80 ° C. with nitrogen sealing, and 1 g of 10% aqueous sodium persulfate solution was added. Subsequently, a monomer solution obtained by dissolving 5 g of sodium hypophosphite in 210 g of the acrylic acid aqueous solution recovered in Example 2 and 10 g of a 10% sodium persulfate aqueous solution were reacted from separate injection ports while maintaining a polymerization temperature of 80 ° C. The solution was continuously added dropwise to the vessel for 4 hours to obtain a polyacrylic acid aqueous solution.
This polyacrylic acid aqueous solution was neutralized with 48% sodium hydroxide to pH = 7.5,
An aqueous sodium polyacrylate solution having a solid content of 41.9% by weight and a viscosity of 264 mPa · s was obtained.
　本発明のアクリレートの製造方法によれば、アクリレートの製造に利用することができ、より好ましくは高沸点アクリレートの製造に利用することができ、分離・回収したアクリル酸は、アクリレートやポリマーの製造に再使用することができる。
　また、本発明のアクリル酸の回収方法によって分離・回収されたアクリル酸は、アクリレートやポリマーの製造に再使用することができる。 According to the acrylate production method of the present invention, it can be used for the production of acrylates, more preferably for the production of high-boiling acrylates. The separated and recovered acrylic acid can be used for the production of acrylates and polymers. Can be reused.
In addition, the acrylic acid separated and recovered by the acrylic acid recovery method of the present invention can be reused in the production of acrylates and polymers.

Claims (6)

  1. 　下記第１工程～第５工程を順次実施するアクリレートの製造方法。
    第１工程：酸触媒の存在下に、アクリル酸とアルコールを攪拌・混合し、エステル化反応させアクリレートを含む反応液を得る工程
    第２工程：第１工程で得られた反応液にアルカリ水溶液を添加して中和した後、有機相と水相の２相に分離させ有機相を分取し、アクリレートを回収する工程
    第３工程：第２工程で得られた水相を分取し、これに硫酸濃度７０重量％以上の硫酸水溶液を添加し、ｐＨを４．０以下に調整し、かつ液中のアクリル酸及び／又はそのアルカリ金属塩の含有割合をアクリル酸換算で１８重量％以上とする工程
    第４工程：第３工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
    第５工程：第４工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程     An acrylate production method in which the following first to fifth steps are sequentially performed.
    First step: A step of stirring and mixing acrylic acid and alcohol in the presence of an acid catalyst to obtain a reaction solution containing acrylate by esterification reaction. Second step: An alkaline aqueous solution is added to the reaction solution obtained in the first step. After neutralization by addition, the organic phase and the aqueous phase are separated into two phases, the organic phase is separated, and the acrylate is recovered. Third step: The aqueous phase obtained in the second step is separated, A sulfuric acid aqueous solution having a sulfuric acid concentration of 70% by weight or more is added to the solution, the pH is adjusted to 4.0 or less, and the content ratio of acrylic acid and / or alkali metal salt thereof in the liquid is 18% by weight or more in terms of acrylic acid Step 4 of Step: The liquid obtained in Step 3 is separated into two phases: a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt and a phase (lower layer) containing a large amount of alkali metal sulfate. Step 5 to perform: Sulfurization of the liquid obtained in Step 4 Recovering the The phases were separated rich in alkali metal salt (lower layer), the remaining acrylic acid and / or a phase rich in alkali metal salt thereof (upper layer)
  2. 　アクリレートが１３．３ｋＰａの圧力下の沸点が１００℃以上のアクリレートである請求項１記載のアクリレートの製造方法。 The method for producing an acrylate according to claim 1, wherein the acrylate is an acrylate having a boiling point of 100 ° C or higher under a pressure of 13.3 kPa.
  3. 　第３工程において、硫酸水溶液添加後のｐＨを１～３．５の範囲とする請求項１又は請求項２記載のアクリレートの製造方法。 The method for producing an acrylate according to claim 1 or 2, wherein in the third step, the pH after addition of the aqueous sulfuric acid solution is in the range of 1 to 3.5.
  4. 　第３工程において、硫酸水溶液の添加を２５℃以上の温度で実施し、第４工程を２５℃から４０℃の温度で実施する請求項１～請求項３のいずれか１項に記載のアクリレートの製造方法。 The acrylate according to any one of claims 1 to 3, wherein, in the third step, the sulfuric acid aqueous solution is added at a temperature of 25 ° C or higher, and the fourth step is performed at a temperature of 25 ° C to 40 ° C. Production method.
  5. 　下記第３’工程～第５’工程を順次実施するアクリル酸の回収方法。
    第３’工程：アクリル酸及び／又はそのアルカリ金属塩、硫酸アルカリ金属塩、並びに、水を含有し、ｐＨが４．０以下であり、かつアクリル酸及び／又はそのアルカリ金属塩の含有割合がアクリル酸換算で１８重量％以上である液を調製する工程
    第４’工程：第３’工程で得られた液を、アクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）と、硫酸アルカリ金属塩を多く含む相（下層）の２相に分離する工程
    第５’工程：第４’工程で得られた液の硫酸アルカリ金属塩を多く含む相（下層）を分取し、残ったアクリル酸及び／又はそのアルカリ金属塩を多く含む相（上層）を回収する工程     A method for recovering acrylic acid, wherein the following third to fifth steps are sequentially performed.
    3 'process: It contains acrylic acid and / or its alkali metal salt, alkali metal sulfate, and water, pH is 4.0 or less, and the content rate of acrylic acid and / or its alkali metal salt is Step of preparing a liquid that is 18% by weight or more in terms of acrylic acid 4 ′ step: The liquid obtained in the 3 ′ step is a phase (upper layer) containing a large amount of acrylic acid and / or its alkali metal salt, and sulfuric acid. Step of separating into two phases of a phase (lower layer) rich in alkali metal salt 5 ′ step: The phase (lower layer) rich in alkali metal sulfate of the liquid obtained in step 4 ′ was separated and remained A step of recovering a phase (upper layer) rich in acrylic acid and / or its alkali metal salt
  6. 　第４’工程を２５℃から４０℃の温度で実施する請求項５に記載のアクリル酸の回収方法。 The method for recovering acrylic acid according to claim 5, wherein the 4 ′ step is performed at a temperature of 25 ° C. to 40 ° C.
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