KR100698624B1 - Method for preparing high purity sulfur-containing methacrylates - Google Patents

Abstract

Provided is a method for preparing a sulfur-containing (meth)acrylate monomer to reduce the amount of the sulfur-containing alcohol remaining in the reaction mixture, thereby improving purity. The method comprises the steps of reacting a sulfur-containing alcohol compound and a (meth)acrylic acid compound or a (meth)acrylate compound in the presence of a direct esterification catalyst or a transesterification catalyst in a reactor to prepare a sulfur-containing (meth)acrylate and by-products; and draining out the reaction mixture of the reactor, removing the by-products from the drained reaction mixture, and flowing the reaction mixture that the by-products are removed into the reactor with keeping pace with the previous step.

Description

Method for preparing high purity sulfur-containing (meth) acrylates}

1 is a process diagram schematically illustrating an apparatus that may be used to practice one embodiment based on the direct-esterification reaction of the process of the present invention.

2 is a process diagram schematically illustrating an apparatus that may be used to practice other embodiments based on the trans-esterification reaction of the process of the present invention.

3 is a process diagram schematically illustrating an apparatus that may be used to practice one embodiment based on the direct-esterification reaction of the process of the present invention.

4 is a process diagram schematically illustrating an apparatus that can be used to practice other embodiments based on the trans-esterification reaction of the process of the present invention.

U.S. Patent 5,191,061, U.S. Patent 6,310,161, U.S. Patent 6,369,269, Japanese Patent Application Laid-Open No. 9-110827, Japanese Patent Application Laid-Open No. 2003-146967, Japanese Patent Application Laid-Open No. 2004-323702.

The present invention relates to a (meth) acrylate production method, and more particularly to a high purity sulfur-containing (meth) acrylate production method.

Sulfur-containing (meth) acrylates are used as monomers for the production of synthetic resins. In particular, sulfur-containing (meth) acrylates are one of the monomers that can be usefully used in the production of optical materials such as optical lenses, optical films, and optical fibers.

In the production of synthetic resin-based optical materials, various monomers capable of causing polymerization by, for example, polymerization initiation factors such as ultraviolet irradiation or heating are used. In order to use the polymer prepared through the polymerization of such monomers as an optical material, it is desirable to have physical properties such as excellent impact resistance, excellent heat resistance, excellent light transmittance, high refractive index, and high Abbe number. Among these, the high refractive index makes it possible to reduce the thickness and weight of the optical lens, and on the one hand, the synthetic resin optical material exhibits weakness compared to the inorganic optical material, which is particularly important for the synthetic resin-based optical material. Physical properties.

Thus, various efforts have been made to provide monomers capable of forming polymers capable of exhibiting these physical properties. As a result, it is known that (meth) acrylate-based monomers containing elemental sulfur in a molecule can form a polymer having a high refractive index.

For example, US Pat. No. 5,191,061, US Pat. No. 6,310,161, and US Pat. No. 6,369,269 disclose various sulfur-containing (meth) acrylate monomers for the manufacture of optical materials and methods for their preparation. As another example, Japanese Patent Laid-Open Nos. 9-110827, 2003-146967 and 2004-323702 also disclose methods for producing various sulfur-containing (meth) acrylate monomers for the production of optical materials. It is. In addition, such sulfur-containing (meth) acrylate monomers often contain an aromatic ring in their molecule.

However, in such a conventional method of producing sulfur-containing (meth) acrylate monomers, expensive raw materials such as (meth) acryloyl chloride are used, or the process consists of very complicated steps. Thus, conventional methods for producing sulfur-containing (meth) acrylate monomers have many aspects that are not suitable for industrial production.

Typically, sulfur-containing alcohols are used as raw materials for synthesizing sulfur-containing (meth) acrylates. However, sulfur-containing alcohols have a relatively high boiling point, and accordingly, the boiling points of the synthesized sulfur-containing (meth) acrylates and the boiling points of the sulfur-containing alcohols as raw materials do not show a great difference. Thus, using general distillation to separate / purify the synthesized sulfur-containing (meth) acrylate from the reaction mixture, it is very difficult to obtain a sulfur-containing (meth) acrylate product in high purity.

Furthermore, to the inventors of the present invention, unreacted sulfur-containing alcohols must be present in the separated / purified sulfur-containing (meth) acrylate product in less than 1% by weight, so that the sulfur-containing (meth) acrylate product can be It has been found that the optical materials produced using have excellent physical properties.

For this reason, in the conventional sulfur-containing (meth) acrylate monomer manufacturing method, it is understood that an overly complicated process and expensive raw materials are used.

Therefore, even when sulfur-containing alcohol having a high boiling point is used as a raw material for synthesizing sulfur-containing (meth) acrylate, a high-purity sulfur-containing (meth) acrylate monomer product is produced through a simple and economic process. There is an urgent need for new manufacturing methods that can be achieved.

The inventors of the present invention, by different approaches, initially reduce the content of sulfur-containing alcohol remaining in the reaction mixture to a target value or less in the course of synthesizing the sulfur-containing (meth) acrylate, In the purification process, it was noted that the need to remove the sulfur-containing alcohol from the reaction mixture can be avoided inherently.

Thus, in the present invention, in the process of synthesizing sulfur-containing (meth) acrylate, it is to provide a new production method that can reduce the content of sulfur-containing alcohol remaining in the reaction mixture to a target value or less.

The sulfur-containing (meth) acrylate monomer production method of the present invention,

(a) reacting a sulfur-containing alcohol compound with a (meth) acrylic acid compound or a (meth) acrylate compound in a reactor, in the presence of a direct-esterification catalyst or in the presence of a trans-esterification catalyst, Producing a containing (meth) acrylate and byproduct; And

(b) In parallel with the step (a), after flowing out the reaction mixture in the reactor to the outside of the reactor, the by-products in the outgoing reaction mixture is removed, and then the spilled reaction mixture in which the by-products are removed It includes; flowing back to the reactor.

In the production method of the present invention, by the step (b), in the course of the reaction mixture in the reactor is circulated through the outside of the reactor, by-products in the reaction mixture is continuously removed, the concentration of the by-products in the reaction mixture in the reactor Can be kept low. Thus, the equilibrium of the reaction process in which the sulfur-containing alcohol compound and the (meth) acrylic acid compound or the (meth) acrylate compound proceed in the reactor to produce a sulfur-containing (meth) acrylate and a byproduct The state is shifted towards forward reaction. Thus, a larger proportion of the sulfur-containing alcohol compound participates in the reaction, and, after completion of the reaction, the content of the sulfur-containing alcohol compound remaining in the reaction mixture in the reactor can be significantly reduced. As a result, in the purification process after completion of the synthesis, the need to remove the sulfur-containing alcohol from the reaction mixture can be prevented at the source.

Hereinafter, the sulfur-containing (meth) acrylate monomer manufacturing method of this invention is demonstrated in detail.

The reactor used in step (a) is not particularly limited, but may be, for example, a reduced pressure, pressurized or atmospheric pressure reactor. In addition, the reactor used in step (a) may be, for example, a batch reactor, a continuous reactor, or a combination thereof. As the continuous reactor, for example, a continuous stirring tank reactor can be used.

The process of the present invention may be based on a direct-esterification reaction or a trans-esterification reaction.

Based on the direct-esterification reaction, step (a) can be carried out in the presence of a direct-esterification reaction catalyst. As the direct-esterification catalyst, non-limiting examples can be used acid catalysts or alkali catalysts which can promote the direct-esterification reaction. More specifically, for example, methane sulfonic acid may be used as the direct-esterification catalyst.

Based on the trans-esterification reaction, step (a) may be carried out in the presence of a trans-esterification reaction catalyst. As the trans-esterification catalyst, for example, an acid catalyst or an alkali catalyst capable of promoting the trans-esterification reaction can be used. More specifically, as a trans-esterification catalyst, titanium (IV) propoxide can be used.

As the sulfur-containing alcohol compound, as well as known sulfur-containing alcohol compounds used for producing sulfur-containing acrylate monomers for synthetic resin optical materials, sulfur-containing alcohol compounds that will be newly developed in the future may also be used. Sulfur-containing alcohol compounds used for the production of sulfur-containing acrylate monomers used in fields other than the field of materials may also be used. In addition, the sulfur-containing alcohol compound may further contain an aromatic ring in the molecule thereof.

The method of the present invention is particularly useful for producing sulfur-containing acrylate monomers for synthetic resin optical materials. Therefore, as the sulfur-containing alcohol compound used in the present invention, it is particularly useful to use the sulfur-containing alcohol compound used for the production of sulfur-containing acrylate monomers for synthetic resin optical materials. In this case, preferably, a sulfur-containing alcohol compound having a boiling point of about 150 ° C. or more, and having a boiling point difference from the synthesized sulfur-containing (meth) acrylate of about 50 ° C. or less under reduced pressure of 20 mmHg or less is used. Can be.

More specific examples of the sulfur-containing alcohol compound include 2- (phenyl thio) ethanol; 2- (phenyl thio) methanol; 2- (naphthyl thio) ethanol; 2- (benzyl thio) ethanol; 2- (naphthyl thio) methanol; 2- (benzyl thio) methanol; 2- (phenyl thiocarbonyl oxy) ethanol; Bis- (phenylthio ethanol) methane; Bis- (naphthyl thioethanol) methane; Compounds in which a halogen atom is substituted in an aromatic ring of these compounds; Or combinations thereof.

When the process of the present invention is based on a direct-esterification reaction, as a (meth) acrylic group source which reacts with a sulfur-containing alcohol compound, a (meth) acrylic acid compound is used. The (meth) acrylic acid compound may be substituted or unsubstituted. As a representative example, acrylic acid, methacrylic acid, or a combination thereof may be used as the (meth) acrylic acid compound.

The total amount of the (meth) acrylic acid compound may be introduced into the reactor at the beginning of step (a), or may be divided into the reactor during the progress of step (a). If the dosage of the (meth) acrylic acid compound is too small, the conversion rate of the sulfur-containing alcohol compound may not be sufficient, and if too large, excessive energy may be required to separate the (meth) acrylic acid compound from the reaction mixture after the reaction is finished. have. Preferably, the input amount of the (meth) acrylic acid compound may be about 1 to about 5 moles, more preferably about 1 to about 3 moles, based on 1 mole of the sulfur-containing alcohol compound.

When the method of the present invention is based on a trans-esterification reaction, a (meth) acrylate compound is used as a (meth) acrylic group source that reacts with a sulfur-containing alcohol compound. The (meth) acrylate compound may be substituted or unsubstituted. For example, as the (meth) acrylate compound, alkyl acrylate, alkyl methacrylate, or a combination thereof can be used.

Preferably, as a (meth) acrylate compound, for example, alkyl which can generate by-products (i.e., the resulting alkanols) which can be easily removed from the reaction mixture via conventional separation techniques such as distillation. Meta) acrylates may be used. In alkyl (meth) acrylates, when the carbon number of the alkyl group is 10 or more, the boiling point of the byproduct (i.e., the produced alkanol) becomes too high, and it may be difficult to selectively remove the byproduct from the reaction mixture by distillation. Therefore, more preferably, as the (meth) acrylate compound, an alkyl (meth) acrylate having 1 to 10 carbon atoms of an alkyl group can be used. Specific examples of the alkyl (meth) acrylate having 1 to 10 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and hexyl (meth). ) Acrylate, 2-ethyl-hexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, or a combination thereof.

The total amount of the (meth) acrylate compound may be added to the reactor at the beginning of step (a), or may be dividedly added to the reactor during the progress of step (a). If the input amount of the (meth) acrylate compound is too small, the conversion rate of the sulfur-containing alcohol compound may not be sufficient, and if too large, excessive energy is required to separate the (meth) acrylate compound from the reaction mixture after the completion of the reaction. It can take. Preferably, the input amount of the (meth) acrylate compound may be about 1 to about 20 moles, more preferably about 1 to about 10 moles, based on 1 mole of the sulfur-containing alcohol compound.

In step (a), sulfur-containing (meth) acrylates and by-products are produced through the reaction of a sulfur-containing alcohol compound with a (meth) acrylic acid compound or a (meth) acrylate compound. If the reaction of step (a) is based on a direct-esterification reaction, the byproduct is product water. If the reaction of step (a) is based on a trans-esterification reaction, the byproduct is the product alcohol compound. More specifically, for example, when an alkyl (meth) acrylate having 1 to 10 carbon atoms of an alkyl group is used as the (meth) acrylate compound, the byproduct is an alkanol having 1 to 10 carbon atoms.

The reaction temperature of step (a) may typically be about 50 to about 150 ° C, preferably, about 70 to about 120 ° C.

The biggest feature of the present invention is that by performing step (b) during step (a), by-products are continuously removed from the reaction mixture in the reactor. According to the inventors of the present invention, even if a minor by-product is present in the reaction mixture in the reactor, the reaction conversion rate in step (a) may not be sufficiently high, and thus, the reaction of the sulfur-containing alcohol compound The residual amount will exceed about 1% by weight, based on the synthesized sulfur-containing (meth) acrylate monomers, which in turn can result in a very poor quality of the produced sulfur-containing (meth) acrylate monomer products. . Thus, the content of byproducts in the reaction mixture in the reactor is preferably about 1000 ppm or less, more preferably about 500 ppm or less.

By performing step (b), it is possible to reduce the content of by-products in the reaction mixture in the reactor. In step (b), in parallel with the step (a), the reaction mixture in the reactor is discharged to the outside of the reactor, and then the by-products in the outflowed reaction mixture are removed, and then the effluent from which the by-products are removed. The reaction mixture is introduced back into the reactor. Through the circulation of the reaction mixture, by-products can be continuously removed from the reaction mixture in the reactor during step (a).

In step (b), various separation techniques, such as, for example, distillation, can be used to remove byproducts from the reaction mixture that has flowed out of the reactor.

Specific examples of byproduct removal using distillation are as follows. That is, in order to remove the by-products in the outflowing reaction mixture, the outflowing reaction mixture is passed through a vaporizer installed outside the reactor, while in the vaporizer, the low-boiling by-products in the outflowing reaction mixture are vaporized Let's do it. The low boiling by-product is, for example, generated water or alkanol having 1 to 10 carbon atoms. As the vaporizer, all kinds of vaporizers capable of vaporizing at least a part of the liquid substance may be used. Preferably, the vaporizer is a container; And installed in the interior of the vessel, may include a heat transfer area expansion means that can maximize the heat transfer area for the reaction mixture. The heat transfer area expansion means may be, for example, a distributor, a random ructured packing material, a structured packing material, or a combination thereof.

In another embodiment of the present invention, when the reaction of step (a) is based on the direct-esterification reaction, a further azeotropic solvent is added to the reactor to remove the produced water more easily. You may. The solvent forms an azeotrope with the generated water generated during the reaction in step (a). The product-solvent azeotrope formed in the reactor may be vaporized by the temperature of the reactor. By discharging the vaporized azeotrope to the outside of the reactor, the effect of removing the generated water in the reaction mixture in the reactor can be further enhanced, so that the effect of inducing the reaction of step (a) toward the forward reaction can be further enhanced. Can be.

As the solvent, for example, benzene, cyclohexane, normal-hexane, heptane, toluene, xylene, methyl isobutyl ketone, or a combination thereof can be used. If the input amount of the solvent is too small, the charging effect may be insignificant, if too large, excessive energy may be required to separate the solvent from the reaction mixture after the reaction is completed. For example, the dosage of the solvent may be about 0.5 to about 5 times the weight of the sulfur-containing alcohol compound.

In another embodiment of the present invention, when the reaction of step (a) is based on a trans-esterification reaction, an azeotrope of the (meth) acrylate compound and the resulting alcohol compound may be formed in the reactor. . This azeotrope can also be vaporized by the temperature of the reactor. By discharging the evaporated azeotrope to the outside of the reactor, the effect of removing the product alcohol compound in the reaction mixture in the reactor can be further enhanced, thereby further enhancing the effect of inducing the reaction of step (a) toward the forward reaction. Can be.

In another embodiment of the present invention, a polymerization inhibitor may be further added to the reactor. During the reaction of step (a), in the reactor, the polymerization of the (meth) acrylic acid compound or (meth) acrylate compound itself may occur. The polymerization inhibitor may serve to prevent such a polymerization reaction. As the polymerization inhibitor, for example, hydroquinone, hydroquinone mono ethyl ether, phenocazine, piperidine, 2,5-di-ter-butyl hydroquinone, 2,6-di-ter-butyl-paracresol , 1-nitroso-2-naphthol, or a combination thereof may be used.

1 is a process diagram that schematically illustrates an apparatus that may be used to practice one embodiment of the method of the present invention. With reference to FIG. 1, preferred embodiments of the process of the invention based on direct-esterification reactions are described in more detail. First, in the reactor 10, a direct-esterification catalyst, a sulfur-containing alcohol compound, a (meth) acrylic acid compound, and an azeotropic agent (solvent capable of forming an azeotrope with the generated water) are introduced. At this time, the total amount of the (meth) acrylic acid compound may be added at a time, and may be added in small portions during the reaction. Then, the temperature of the reactor 10 is raised to an appropriate reaction temperature so that the direct-esterification reaction proceeds in the reactor 10. By-products (ie, product water) are removed through two routes. First, as the main path, the reaction mixture in the reactor 10, through the conduit 60, the transfer pump 61 and the conduit 62, outflow of the reactor 10, and then supplied to the vaporizer 20 do. In the vaporizer | carburetor 20, the product water which is a low boiling point component in the outflowing reaction mixture is vaporized mainly. The vaporized generated water is joined to the conduit 70 through the conduit 63, and then condensed while passing through the heat exchanger 30, and flows into the reservoir 40. Most of the effluent reaction mixture not vaporized in the vaporizer 20 is returned to the reactor 10 via conduits 64. Secondly, as an auxiliary route, the azeotrope of the adjuvant and the product water vaporized in the reactor 10 flows out of the reactor 10 through the conduit 70 and then passes through the heat exchanger 30. Condensation. The condensed azeotrope enters the reservoir 40. Since the condensed azeotrope and the condensed product water are stored together in the storage tank 40, the azeotropic composition of the azeotrope mixture is broken in the storage tank 40, whereby the separation of the generated water and the azeotropic agent occurs. The layered product water is discharged through the conduit 120 under the reservoir 40. The layered utilities may be returned to the reactor 10 and reused via conduit 50, transfer pump 51 and conduit 52.

With reference to FIG. 2, preferred embodiments of the process of the invention based on trans-esterification reactions are described in more detail. First, a trans-esterification catalyst, a sulfur-containing alcohol compound and a (meth) acrylate compound are introduced into the reactor 10. At this time, the total amount of the (meth) acrylate compound may be added at one time, or may be added in small portions over the course of the reaction. Then, the temperature of the reactor 10 is raised to an appropriate reaction temperature so that the trans-esterification reaction proceeds in the reactor 10. By-products (ie product alcohols) are removed through two pathways. First, as the main path, the reaction mixture in the reactor 10, through the conduit 60, the transfer pump 61 and the conduit 62, outflow of the reactor 10, and then supplied to the vaporizer 20 do. In the vaporizer | carburetor 20, the product alcohol which is a low boiling point component in the outflowing reaction mixture is vaporized mainly. The vaporized product alcohol is joined to the conduit 70 through the conduit 63, and then condensed while passing through the heat exchanger 30, and flows into the reservoir 40. Most of the effluent reaction mixture not vaporized in the vaporizer 20 is returned to the reactor 10 via conduits 64. Second, as an auxiliary route, after the azeotrope of the (meth) acrylate compound and the product alcohol vaporized in the reactor 10 flows out of the reactor 10 through the conduit 70, the heat exchanger 30 Is condensed through). The condensed azeotrope enters the reservoir 40. The reservoir 40 stores the condensed azeotrope and the condensed product alcohol together. The condensed azeotrope and the condensed product alcohol stored in the reservoir 40 are entirely discharged through the conduit 120 since no delamination occurs.

<Example>

Example  1 --- direct- Esterification

In this embodiment based on the direct-esterification reaction, the produced water in the reaction mixture was removed using a vaporizer configured by filling a glass tube 5 mm in diameter with a 5 cm diameter and 10 cm high heat-insulated glass tube. In addition, auxiliary water was used to remove the generated water in the reaction mixture.

First, 385.6 g of 2- (phenylthio) ethanol, 198 g of acrylic acid, and 400 g of cyclohexane were added as a co-agent in a 2 liter glass reactor equipped with a stirrer. Next, 6.5 g of methanesulfonic acid was added as a direct-esterification catalyst. Next, 0.18 g of phenocyazine and 0.3 g of hydroquinone were added as a polymerization inhibitor. The temperature of the reactor was then raised to allow the direct-esterification reaction to proceed. As the reaction proceeded, the reaction temperature started at 92 ° C. and increased to 96 ° C.

Meanwhile, while the reaction was in progress, the reaction mixture was discharged from the reactor by using a metering pump, passed through a vaporizer, and then circulated back to the reactor. The product water vaporized in the vaporizer was sent to the cooler to liquefy and then introduced into the reservoir. In addition, the azeotrope of cyclohexane vaporized in the reactor and the resulting water was flowed out of the reactor, and then liquefied with a cooler, and then introduced into the reservoir. The cyclohexane layered in the reservoir was re-introduced into the reactor at a flow rate of 100 ml / min using a metering pump.

During the reaction, the water content of the reaction mixture in the reactor was measured using a Karl Fischer analyzer. As a result, it was confirmed that the water content in the reaction mixture was maintained within the range of 50 to 380 ppm over the entire reaction time.

6 hours after the start of the reaction, the reaction mixture in the reactor was analyzed by gas chromatography to confirm that the content of residual 2- (phenyl thio) ethanol in the reaction mixture in the reactor was 0.46% by weight, and the reaction was terminated.

After the completion of the reaction, the reaction mixture in the reactor was distilled under reduced pressure to remove cyclohexane, which is an adjuvant, followed by distillation to remove high-boiling impurities in the reaction mixture, thereby obtaining 2- (phenyl thio) ethyl acrylate monomer product.

As a result of gas chromatography analysis of the components of the 2- (phenyl thio) ethyl acrylate monomer product obtained through this simple purification process, the content of 2- (phenyl thio) ethyl acrylate was 99.2% by weight, and the remaining 2- ( The content of phenyl thio) ethanol was only 0.52% by weight, the rest being other high boiling impurities.

Example  2 --- trans- Esterification

In the present embodiment based on the trans-esterification reaction, the product alcohol (ethanol) in the reaction mixture is removed using a vaporizer configured by filling a 5 cm diameter, 10 cm high, insulated glass tube with a 5 mm diameter glass sphere. It was.

First, 385.6 g of 2- (phenylthio) ethanol and 650 g of ethyl acrylate were charged into a 2-liter glass reactor provided with a stirrer. Next, 8.0 g of titanium propoxide was added as a trans-esterification catalyst. Next, 0.2 g of phenocyazine was added as a polymerization inhibitor. Then, the temperature of the reactor was raised and the reaction proceeded at 95 ° C.

On the other hand, while the reaction was in progress, by using a metering pump, the reaction mixture flowed out of the reactor at a flow rate of 100 ml / min, passed through the vaporizer, and then circulated back to the reactor. The product alcohol vaporized in the vaporizer was sent to the cooler to liquefy and then introduced into the reservoir. In addition, the azeotrope of ethyl acrylate and alcohol produced in the reactor was allowed to flow out of the reactor, and then liquefied with a cooler, and then introduced into a reservoir.

While the reaction was in progress, the ethanol content of the reaction mixture in the reactor was measured using gas chromatography. As a result, it was confirmed that the ethanol content in the reaction mixture was maintained within the range of 180 to 470 ppm over the entire reaction time.

When 5 hours had elapsed after the start of the reaction, the reaction temperature was increased to 105 ° C. At this time, the reaction mixture in the reactor was analyzed by gas chromatography, and the content of residual 2- (phenylthio) ethanol in the reaction mixture in the reactor was 0.82. Confirmed by weight percent, the reaction was terminated.

After completion of the reaction, the reaction mixture in the reactor was distilled under reduced pressure to remove the excessively charged ethyl acrylate, and then distillation removed the high boiling impurities in the reaction mixture, thereby obtaining 2- (phenyl thio) ethyl acrylate monomer product.

As a result of gas chromatography analysis of the components of the 2- (phenyl thio) ethyl acrylate monomer product obtained through this simple purification process, the content of 2- (phenyl thio) ethyl acrylate was 99.1% by weight, and the remaining 2- ( The content of phenyl thio) ethanol was only 0.85% by weight, the rest being other high boiling impurities.

Comparative example  One --- Carburetor  Unused Direct- Esterification

A 2- (phenyl thio) ethyl acrylate monomer product was prepared in the same manner as in Example 1 except that the reaction was not circulated with a vaporizer. The reaction time was 6 hours. During the reaction, the water content of the reaction mixture in the reactor was maintained in the range of 2100 to 3500 ppm. Further, the content of residual 2- (phenylthio) ethanol in the 2- (phenylthio) ethyl acrylate monomer product was 2.67% by weight. In addition, due to the high water content of the reaction mixture, the content of high boiling point impurities in the 2- (phenyl thio) ethyl acrylate monomer product was also very high.

Comparative example  2 --- Carburetor  Unused Trans Esterification

A 2- (phenyl thio) ethyl acrylate monomer product was prepared in the same manner as in Example 2 except that the reaction was not circulated with the vaporizer. During the reaction, the ethanol content of the reaction mixture in the reactor was maintained in the range of 1800 to 2500 ppm.

Once, the reaction was carried out for 5 hours and then measured. The content of residual 2- (phenylthio) ethanol in the reaction mixture was 4.56 wt%. Thereafter, the reaction was further proceeded for 5 hours, but the content of residual 2- (phenylthio) ethanol in the reaction mixture was 4.47% by weight. Thus, the reaction was terminated, confirming that the conversion of 2- (phenyl thio) ethanol could no longer be increased. The content of residual 2- (phenylthio) ethanol in the 2- (phenylthio) ethyl acrylate monomer product was 4.47 wt%.

Evaluation results

Example 1 and Comparative Example 1 are both based on a direct-esterification reaction. In Example 1, the water content in the reaction mixture was kept very low in the range of 50 to 380 ppm by continuously removing the generated water in the reaction mixture using a vaporizer installed outside the reactor. On the other hand, in Comparative Example 1, although the azeotrope of the vaporized adjuvant and the produced water was discharged to the outside of the reactor, since the vaporizer was not used, the water content in the reaction mixture was in the range of 2100 to 3500 ppm. Stayed very high. Due to the difference in the amount of by-products in the reaction mixture, the reaction conversion rate of the sulfur-containing alcohol compound in Example 1 was significantly higher than in Comparative Example 1. As a result, the content of the residual sulfur-containing alcohol compound in the monomer product finally obtained through a simple purification process was very low as 0.52% by weight in Example 1, but very high as 2.67% by weight in Comparative Example 1.

Example 2 and Comparative Example 2 are both based on the trans-esterification reaction. In Example 2, the ethanol content in the reaction mixture was kept very low in the range of 180 to 470 ppm by continuously removing the product alcohol in the reaction mixture using a vaporizer installed outside the reactor. On the other hand, in Comparative Example 2, even though the azeotrope of vaporized ethyl acrylate and alcohol produced was discharged to the outside of the reactor, since the vaporizer was not used, the ethanol content of the reaction mixture was in the range of 1800 to 2500 ppm. Remained very high at. Due to the difference in the amount of by-products in the reaction mixture, the reaction conversion rate of the sulfur-containing alcohol compound in Example 2 was significantly higher than in Comparative Example 2. Finally, the content of residual sulfur-containing alcohol compound in the monomer product finally obtained through a simple purification process was very low as 0.85% by weight in Example 2, but was very high as 4.47% by weight in Comparative Example 2. .

In the present invention, sulfur-containing alcohol compounds which can be easily and economically produced in high purity sulfur-containing (meth) acrylate monomer products using as raw materials sulfur-containing alcohol compounds that are difficult to remove by simple purification methods such as distillation. A method for producing a (meth) acrylate monomer was provided.

Claims (10)

(a) reacting a sulfur-containing alcohol compound with a (meth) acrylic acid compound or a (meth) acrylate compound in a reactor, in the presence of a direct-esterification catalyst or in the presence of a trans-esterification catalyst, Producing a containing (meth) acrylate and byproduct; And (b) In parallel with the step (a), after flowing out the reaction mixture in the reactor to the outside of the reactor, the by-products in the outgoing reaction mixture is removed, and then the spilled reaction mixture in which the by-products are removed The sulfur-containing (meth) acrylate monomer production method comprising the step of introducing into the reactor again. The sulfur-containing alcohol compound according to claim 1, wherein the sulfur-containing alcohol compound has a boiling point of 150 ° C. or more, and the difference between the boiling point of the sulfur-containing alcohol compound and the boiling point of the synthesized sulfur-containing (meth) acrylate is 20 mmHg or less. A process for producing a sulfur-containing (meth) acrylate monomer, characterized in that it is 50 ° C. or less under reduced pressure. The compound of claim 1, wherein the sulfur-containing alcohol compound is selected from 2- (phenyl thio) ethanol; 2- (phenyl thio) methanol; 2- (naphthyl thio) ethanol; 2- (benzyl thio) ethanol; 2- (naphthyl thio) methanol; 2- (benzyl thio) methanol; 2- (phenyl thiocarbonyl oxy) ethanol; Bis- (phenylthio ethanol) methane; Bis- (naphthyl thioethanol) methane; Compounds in which a halogen atom is substituted in an aromatic ring of these compounds; Or a combination thereof, sulfur-containing (meth) acrylate monomer production method. The method for producing a sulfur-containing (meth) acrylate monomer according to claim 1, wherein the (meth) acrylate compound is an alkyl (meth) acrylate having 1 to 10 carbon atoms in the alkyl group. The method of claim 1, wherein the reaction temperature of the step (a) is 50 to 150 ℃, characterized in that the sulfur-containing (meth) acrylate monomer production method. The method of claim 1, wherein the byproduct content in the reaction mixture in the reactor is maintained at 1000 ppm or less. The method of claim 1, wherein in step (b), a distillation method is used to remove by-products from the reaction mixture flowing out of the reactor. . 8. The method of claim 7, wherein step (b) passes the outflowed reaction mixture through a vaporizer installed outside of the reactor to remove by-products from the reaction mixture flowing out of the reactor. In the vaporizer, the sulfur-containing (meth) acrylate monomer manufacturing method comprising the step of vaporizing the by-product in the outflow reaction mixture. The process of claim 1, wherein the reaction of step (a) is based on a direct-esterification reaction; In the reactor, in order to more easily remove the generated water, a solvent capable of achieving azeotropy with water is further added; The method of producing a sulfur-containing (meth) acrylate monomer, characterized in that further comprising the step of discharging the azeotrope of the solvent and the product water vaporized by the temperature of the reactor to the outside of the reactor. The process of claim 1, wherein the reaction of step (a) is based on a trans-esterification reaction; The production method further comprises the step of discharging the azeotrope of the (meth) acrylate compound and the resulting alcohol compound, vaporized by the temperature of the reactor, to the outside of the reactor, sulfur-containing (meth) Acrylate monomer production method.

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