JP5128151B2 - Method for preventing polymerization of easily polymerizable compounds - Google Patents

Description

  The present invention relates to a method for preventing polymerization of easily polymerizable compounds.

  Easily polymerizable compounds such as (meth) acrylic acid and esters thereof are industrially important production raw materials, and are produced in large quantities in large-scale plants. In each step in the production of the easily polymerizable compound, since the gas phase and the liquid phase are mixed, it is necessary to suppress the polymerization of the easily polymerizable compound in both the liquid phase and the gas phase.

  In order to prevent polymerization of the easily polymerizable compound, compounds having various polymerization stabilizing actions are used. Since many of these compounds having a polymerization stabilizing action are compounds having a boiling point higher than that of an easily polymerizable compound, a compound having a polymerization stabilizing action is not sufficiently present in the gas phase. For this reason, polymerization is likely to occur when the evaporated easily polymerizable compound is condensed.

  As a method for preventing such polymerization in the gas phase, a method of introducing a vaporized or sublimated compound having a polymerization stabilizing action is known (for example, see Patent Document 1).

Further, a method of introducing NO ₂ as a gaseous compound having a polymerization inhibiting action is known (for example, see Patent Document 2).
JP 2001-348358 A (released on December 18, 2001) International Publication No. 01/038285 pamphlet (published on May 31, 2001) (corresponding domestic publication gazette: JP 2003-532631 gazette)

  However, in the configuration of Patent Document 1, it is necessary to heat to a high temperature in order to vaporize or sublimate and introduce a compound having a polymerization stabilizing effect, and the ability to suppress polymerization is lost due to a structural change of the compound having a polymerization stabilizing effect. Or problems such as an increase in coloring components.

  Specifically, in the method described in Patent Document 1, a method of heating and sublimating a compound having a polymerization stabilizing action, and a method of generating a vapor by heating after forming a solution can be considered. Even so, in order to introduce a compound having a gaseous polymerization stabilizing action, the pressure in the apparatus for vaporizing the compound having a polymerization stabilizing action is set to be higher than the pressure in the apparatus for introducing the compound having a polymerization stabilizing action. It is necessary to heat the compound having a polymerization stabilizing action to a high temperature.

  Further, Patent Document 1 does not describe any method for controlling the introduction amount of a compound having a polymerization stabilizing action, so it has been difficult to control the introduction amount of a compound having a polymerization stabilizing action.

  Furthermore, in the configuration of Patent Document 2, it is not necessary to heat a compound having a polymerization stabilizing action to a high temperature, but since there are few kinds of gaseous compounds having a polymerization inhibiting action at room temperature, applicable easy polymerizability. The problem is that the types of compounds are limited.

  The present invention has been made in view of the above problems, and its purpose is to suppress the disappearance of the polymerization inhibitory ability of a compound having a polymerization stabilizing action, and to many types of easily polymerizable compounds. An object of the present invention is to realize a method for preventing polymerization of easily polymerizable compounds, which can efficiently prevent polymerization in a gas phase in an apparatus that handles easily polymerizable compounds.

  In order to solve the above-mentioned problem, the method for preventing polymerization of a readily polymerizable compound according to the present invention is a liquid or solid liquid or solid at normal temperature and pressure, in a gaseous state, together with a non-condensable gas, It is characterized by being introduced into an apparatus that handles easily polymerizable compounds.

  According to the above method, since the compound having the polymerization stabilizing action is introduced in a gaseous state together with the non-condensable gas, the compound having the polymerization stabilizing action is in the gaseous state without heating the compound having the polymerization stabilizing action to a high temperature. It can be introduced into an apparatus that handles easily polymerizable compounds. In addition, since the compound having a polymerization stabilizing action is introduced together with the non-condensable gas, it is easy to control the amount of the compound having a polymerization stabilizing action.

  Therefore, the disappearance of the ability to suppress the polymerization of a compound having a polymerization stabilizing effect is suppressed, and for various types of easily polymerizable compounds, polymerization in the gas phase in an apparatus that handles the easily polymerizable compounds is efficiently prevented. There is an effect that can be done.

  In the method for preventing polymerization of an easily polymerizable compound according to the present invention, it is preferable to introduce the compound having the polymerization stabilizing action into a gas phase in an apparatus that handles the easily polymerizable compound.

  According to the said method, there exists the further effect that the superposition | polymerization which occurs in the gaseous phase in the apparatus which handles an easily polymerizable compound can be suppressed more effectively.

  As described above, the method for preventing polymerization of a readily polymerizable compound according to the present invention is a liquid or solid compound having a polymerization stabilizing action that is liquid or solid at normal temperature and normal pressure, and is easily polymerizable together with a non-condensable gas. It is characterized by being introduced into an apparatus for handling compounds.

  As a result, the disappearance of the polymerization inhibitory ability of the compound having a polymerization stabilizing action is suppressed, and the polymerization in the gas phase in the apparatus handling the easily polymerizable compound is efficiently performed for many kinds of easily polymerizable compounds. There is an effect that it can be prevented.

  That is, since the disappearance of the polymerization inhibitory ability of the compound having the polymerization stabilizing action can be suppressed, the compound having the polymerization stabilizing action introduced into the apparatus for vaporizing the compound having the polymerization stabilizing action can be used without loss. Is advantageous. In addition, since it is easy to control the introduction amount of a compound having a polymerization stabilizing action, a compound having a polymerization stabilizing action even when the concentration of the compound having a polymerization stabilizing action in the system is easily changed as in batch distillation. The concentration of can be kept constant.

  Hereinafter, the present invention will be described in detail. However, the scope of the present invention is not limited to these descriptions, and modifications other than the following examples can be made as appropriate without departing from the spirit of the present invention. In the present specification, “X to Y” indicating a range indicates X or more and Y or less.

  The method for preventing polymerization of an easily polymerizable compound according to the present embodiment is a liquid or solid compound having a polymerization stabilizing action that is liquid or solid at normal temperature and atmospheric pressure, and handles the easily polymerizable compound together with a non-condensable gas. Install in the device.

  The non-condensable gas means a gas having a dew point equal to or lower than the temperature in the polymerization inhibitor introduction apparatus. For example, in a rare gas such as air, oxygen, nitrogen, carbon dioxide, and helium, and a mixture and manufacturing process thereof. Examples include generated exhaust gas. Moreover, it is preferable that the oxygen concentration in non-aggregating gas exists in the range of 1-21 volume%. When the oxygen concentration in the non-aggregating gas is less than 1% by volume, the possibility that the easily polymerizable compound causes polymerization is increased, and when the oxygen concentration exceeds 21% by volume, it is not economical.

  Examples of the easily polymerizable compound include α, β-unsaturated carboxylic acids and esters thereof, and specific examples include (meth) acrylic acid and esters thereof. Examples of the ester include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, benzyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylic acid 2 -Acrylic esters such as ethylhexyl, trimethylolpropane triacrylate, isononyl acrylate, isooctyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate Cyclohexyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-ethylhexyl methacrylate, trimethyltrimethacrylate Methacrylic acid esters such as trimethylol propane and the like.

  (Meth) acrylic acid is mentioned as an easily polymerizable compound in this invention other than the specific compound illustrated above. In the case of (meth) acrylic acid, a gas having an effect of preventing polymerization in the form of the present invention is introduced together with a non-condensable gas into a process where a polymer is easily generated. Specifically, in a process that needs to suppress the generation of a polymer, such as a gas collection process or a condensation process of gas containing (meth) acrylic acid after vapor phase oxidation, an azeotropic dehydration process, a high boiling point separation process, etc. It may be a form in which a gas having a polymerization preventing effect is directly introduced together with a non-condensable gas. More specifically, for example, in a form in which propylene or isobutylene as a raw material gas is subjected to a gas phase oxidation reaction, and the gas is condensed or collected with a solvent to produce acrylic acid or methacrylic acid, a gas phase oxidation reactor From the introduction pipe for introducing acrylic acid gas or methacrylic acid gas to the next condensation or solvent collection step, a gas having an effect of preventing polymerization may be introduced together with the non-condensable gas.

  As the compound having a polymerization stabilizing action, a compound known as a conventionally known polymerization inhibitor can be used. For example, phenol compounds, paraphenylenediamines, amine compounds, dialkyldithiocarbamic acid copper salts, N-oxyl. Examples thereof include compounds, nitroso compounds, and decomposition products thereof. These compounds may be used alone or in combination of two or more.

  Examples of the phenol compounds include hydroquinone, methyl hydroquinone, tert-butyl hydroquinone, 2,6-di-tert-butyl hydroquinone, 2,5-di-tert-butyl hydroquinone, and 2,4-dimethyl-6-tert. -Butylphenol, hydroquinone monomethyl ether, etc. are mentioned.

  Examples of the paraphenylenediamines include N-isopropyl-N′-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, and N- (1- Methylheptyl) -N′-p-phenylenediamine, N, N′-di-2-naphthyl-p-phenylenediamine and the like.

  Examples of the amine compounds include thiodiphenylamine and phenothiazine.

  Examples of the copper dialkyldithiocarbamate include copper dibutyldithiocarbamate, copper diethyldithiocarbamate, and copper dimethyldithiocarbamate.

  Examples of the N-oxyl compounds include 2,2,4,4-tetramethylazetidine-1-oxyl, 2,2-dimethyl-4,4-dipropylazetidine-1-oxyl, 2,2 , 5,5-tetramethylpyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-3-oxopyrrolidine-1-oxyl, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4, -Hydroxy-2,2,6,6-tetramethyl-4-acetoxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-benzoyloxypiperidine-1-oxyl, 4,4 ', 4 '' -Tris- (2,2,6,6-tetramethylpiperidine-1-oxyl) phosphite, 4,4′-bis- (2,2,6,6-tetramethylpiperidine-1-oxyl) Sebake Such as theft and the like.

  Examples of the nitroso compounds include p-nitrosophenol, nitrosobenzene, N-nitrosodiphenylamine, isononyl nitrite, N-nitrosocyclohexylhydroxylamine, N-nitrosophenylhydroxylamine, N, N′-dinitrosophenylenediamine or Examples thereof include salts of these compounds.

  The polymerization inhibitor that can be used in the present embodiment is such that when a monomer is radicalized by heat or the like, the polymerization reaction is stopped by reacting with the radical before polymerizing with another monomer. It is a compound having a functional group (structure) capable of Generally, such a functional group possessed by a polymerization inhibitor is highly active, so it is considered that it is partially altered by heat or the like (for example, hydroquinone is changed to benzoquinone by heat or acid).

  However, since the environment where the polymerization inhibitor is actually used is an environment where the monomer is easily polymerized (that is, an environment where heat or the like is applied), the polymerization inhibitor is altered. For this reason, by using the addition method of the polymerization inhibitor of the present application, such alteration of the polymerization inhibitor can be mitigated or eliminated.

  Hereinafter, the method for preventing polymerization of the easily polymerizable compound according to the present invention will be described with reference to FIGS.

  In the method for preventing polymerization of an easily polymerizable compound according to the present invention, for example, by using the polymerization-inhibiting easily polymerizable compound handling device 50 shown in FIG. The compound 34 can be introduced into the easily polymerizable compound handling device (device for handling easily polymerizable compounds) 20 together with the non-condensable gas in a gaseous state.

  As shown in FIG. 1, the polymerization-inhibiting easily polymerizable compound handling device 50 has a configuration in which a polymerization inhibitor introducing device 40 and an easily polymerizable compound handling device 20 are connected via a pipe 7. The pipe 7 can be provided with a valve for controlling the flow rate.

  In the polymerization inhibitor introducing apparatus 40, the heating means 5 for adjusting the temperature, the stirring means 1 for uniformly stirring the compound 34 having a polymerization stabilizing action, and the non-condensable gas are polymerized in the reaction vessel 6. Non-condensable gas introduction means 41 for introduction into the inhibitor introduction device 40 is provided.

  In the easily polymerizable compound handling apparatus 20, the reaction vessel 16 is provided with a heating means 15 for adjusting the temperature and a stirring means 11 for uniformly stirring the easily polymerizable compound 14. Further, for example, a capacitor 51 is provided so that the easily polymerizable compound 14 can be refluxed. In the case of using the easily polymerizable compound handling device 20, the end of the pipe 7 on the easily polymerizable compound handling device 20 side may be provided not only in the reaction vessel 16 but also in the capacitor 51. Thereby, also in the capacitor | condenser 51, superposition | polymerization of the easily polymerizable compound 14 can be prevented efficiently.

  The end of the pipe 7 on the polymerization inhibitor introduction device 40 side introduces the compound 34 having a polymerization stabilizing action in a gaseous state into the easily polymerizable compound handling apparatus 20, and therefore, is higher than the liquid level of the compound 34 having a polymerization stabilizing action. It is provided at a high position. Similarly, the end of the pipe 7 on the side of the easily polymerizable compound handling device 20 is located in the gas phase in the reaction vessel 16, and a compound 34 having a polymerization stabilizing action is introduced into the gas phase in the reaction vessel 16 in a gaseous state. can do.

  In the method for preventing polymerization of an easily polymerizable compound according to the present invention, the compound 34 having a polymerization stabilizing effect is introduced into the easily polymerizable compound handling apparatus 20 together with a non-condensable gas in a gaseous state. Specifically, the non-condensable gas is introduced into the polymerization inhibitor introduction device 40 by the non-condensable gas introduction means 41, and the pressure in the polymerization inhibitor introduction device 40 is changed from the pressure in the easily polymerizable compound handling device 20. By increasing the height, the compound 34 having a polymerization stabilizing effect is easily introduced into the easily polymerizable compound handling apparatus 20 in a gaseous state. For this reason, since it is not necessary to heat the compound 34 which has a superposition | polymerization stabilization effect more than necessary, the loss | disappearance of the superposition | polymerization suppression ability of the compound 34 which has a superposition | polymerization stability effect can be suppressed.

  When the non-condensable gas is introduced into the polymerization inhibitor introduction apparatus 40 by the non-condensable gas introduction means 41, if the compound 34 having a polymerization stabilizing action exists as a liquid in the polymerization inhibitor introduction apparatus 40, the polymerization stability A non-condensable gas may be introduced into the liquid of the compound 34 having an action, or may be introduced into the air in the polymerization inhibitor introduction apparatus 40.

  In addition, it is more preferable that the polymerization-preventing and easily polymerizable compound handling device 50 includes a device capable of adjusting the flow rate of the compound 34 having a polymerization stabilizing action. Thereby, for example, even when the amount of the compound 34 having a polymerization stabilizing action contained in the vapor changes due to the change in the composition according to the change in the distillation rate as in batch distillation, The compound 34 having a polymerization stabilizing effect can be introduced into the polymerizable compound handling apparatus 20 without excess or deficiency.

The flow rate of the non-condensable gas introduced into the polymerization inhibitor introduction apparatus 40 is 50 vol% / h or more with respect to the capacity of the polymerization inhibitor introduction apparatus 40 (that is, the capacity of the polymerization inhibitor introduction apparatus 40 is 1 m ^3). If it is, it is 0.5 m < ³ > / h or more), and it is preferable that it exists in the range of 5 volume% or less with respect to the amount of coagulated vapor | steams in a capacitor | condenser part. When the flow rate of the non-condensable gas is small, the compound 34 having a polymerization stabilizing action cannot be efficiently introduced into the easily polymerizable compound handling apparatus 20, and when the flow rate of the non-condensable gas is too large, the reaction Liquid loss increases.

  The flow rate of the non-condensable gas introduced into the polymerization inhibitor introduction devices 60 and 70 is 50 vol% / h or more with respect to the capacity of the polymerization inhibitor introduction devices 60 and 70, and in a standard state (0 ° C., 1013 hPa). The amount is preferably within a range of 5 vol% or less with respect to the amount of distillate component vapor in the polymerization inhibitor introduction devices 60 and 70. Also in this case, if the flow rate of the non-condensable gas is small, the compound 34 having a polymerization stabilizing action cannot be efficiently introduced into the easily polymerizable compound handling devices 60 and 70, and the flow rate of the non-condensable gas is high. If too much, there is a tendency for the loss of the distillate to increase.

  The pressure in the polymerization inhibitor introducing device 40 is not particularly limited as long as it is higher than the pressure in the easily polymerizable compound handling device 20, and can be set within a range of 1 to 100 hPa, for example.

  By using the polymerization-inhibiting easily polymerizable compound handling apparatus 50, the compound having a polymerization stabilizing action is not heated to a high temperature in the easily polymerizable compound handling apparatus 20, so that the compound 34 having a polymerization stabilizing action is decomposed. By-product high boiling point compounds and the like are not mixed in the easily polymerizable compound handling apparatus 20. For this reason, the amount of impurities mixed in the easily polymerizable compound 14 is reduced, and the subsequent purification process can be simplified.

  In addition, it is known that a high boiling point compound by-produced during decomposition of the compound 34 having a polymerization stabilizing action may contain a substance having an action of promoting polymerization (for example, JP-A-2001-2001). 348358). Even when the high-boiling point compound contains a substance having an action of promoting polymerization, the substance having an action of promoting polymerization is easily polymerized by using the polymerization-inhibiting easily polymerizable compound handling apparatus 50. It can suppress mixing with the compound 14.

  Accordingly, the disappearance of the polymerization inhibiting ability of the compound 34 having a polymerization stabilizing action is suppressed, and the polymerization in the gas phase in the easily polymerizable compound handling apparatus 20 is efficiently performed for many kinds of easily polymerizable compounds. Can be prevented.

  Further, in the above method, the compound 34 having a polymerization stabilizing action is introduced into the easily polymerizable compound handling apparatus 20 together with a non-condensable gas in a gaseous state, and the compound 34 having a polymerization stabilizing action is non-condensable. Since it is diluted with gas, the amount of the compound 34 having a polymerization stabilizing effect can be adjusted more finely. Thereby, since it can suppress that the compound 34 which has a superposition | polymerization stabilization effect | action in excess in the easily polymerizable compound handling apparatus 20 can be suppressed, superposition | polymerization of the easily polymerizable compound 34 can be suppressed at lower cost. .

  If oxygen is necessary to exert the effect of inhibiting the polymerization of the compound 34 having a polymerization stabilizing action, oxygen is introduced into the easily polymerizable compound handling apparatus 20 simultaneously with the compound 34 having a polymerization stabilizing action. Alternatively, oxygen alone may be separately introduced into the easily polymerizable compound handling apparatus 20 and mixed.

  In addition, the compound 34 having a polymerization stabilizing action can be introduced into the gas phase and / or the liquid phase in the easily polymerizable compound handling apparatus 20, but is preferably introduced into the gas phase. Thereby, since the compound 34 which has a polymerization stabilization effect | action can exist more efficiently in the gaseous phase of the easily polymerizable compound handling apparatus 20, the easily polymerizable compound in the gaseous phase in the easily polymerizable compound handling apparatus 20 is obtained. 14 polymerization can be more efficiently prevented. In addition, the compound 34 having a polymerization stabilizing action is directly introduced into a place where a polymer is easily generated in the gas phase of the polymerizable compound handling apparatus 20 (for example, a place where the vapor of the easily polymerizable compound is easily condensed). It is more preferable.

  Vaporization of the compound 34 having a polymerization stabilizing action introduces a non-condensable gas into the polymerization inhibitor introduction apparatus 40, so that it is not necessary to apply heat more than necessary. It can be carried out by heating in a range of 0 ° C. or higher and 10 ° C. or lower than the liquid temperature in the easily polymerizable compound handling device 20.

  Various methods can be used to promote vaporization of the compound 34 having a polymerization stabilizing effect. Specifically, stirring may be performed, or the compound 34 having a polymerization stabilizing action may be dissolved in a solvent or the like.

  Although it does not specifically limit as a solvent which melt | dissolves the compound 34 which has the said polymerization stabilization effect | action, It uses after the process using the product finally obtained from the easily polymerizable compound 14, or the polymerization inhibitory easily polymerizable compound handling apparatus 50. It is preferable to use a solvent contained in the reaction process liquid (for example, reaction liquid, distillation residue, etc.) or a high boiling point solvent that does not easily generate steam because it can be easily removed.

  The easily polymerizable compound handling apparatus 20 exemplified in the above-described method is not particularly limited as long as it is an apparatus that handles the easily polymerizable compound 14, but the polymerization inhibiting component is efficiently supplied to the location where the easily polymerizable compound aggregates. Thus, an apparatus having a mechanism for moving gas is more preferable.

  As the easily polymerizable compound handling apparatus 20, specifically, a reaction apparatus for producing the above easily polymerizable compound, a reaction apparatus for reacting the above easily polymerizable compound with another substance, and the above easily polymerizable substance. Examples thereof include a mixing device for mixing the compound with another substance, a purification device for purifying the easily polymerizable compound such as a distillation device and a filtration device, and a tank for storing the easily polymerizable compound. Specifically, instead of the easily polymerizable compound handling device 20, an easily polymerizable compound handling device 70 shown in FIG. 2 may be used.

  In the easily polymerizable compound handling apparatus 70 shown in FIG. 3, a separation column 61 for separating the components of the easily polymerizable compound 14 is provided in the reaction vessel 16 in order to distill and purify the easily polymerizable compound 14. The separation tower 61 includes a condenser 51 for cooling the easily polymerizable compound 14 separated by the separation tower 61, and a distillation tank 62 for recovering the easily polymerizable compound 14 cooled by the condenser 51. They are connected by piping in order. A pressure reducing device 64 for reducing the pressure in the easily polymerizable compound handling device 70 is provided, and is connected to a pipe branched from the pipe between the condenser 51 and the distillation tank 62. A decompression device protection capacitor 63 for preventing the decompression device 64 from sucking the easily polymerizable compound 14 and the like between the piping between the condenser 51 and the distillation tank 62 and the decompression device 64. Is provided. In the case of using the easily polymerizable compound handling device 70, the end of the pipe 7 on the easily polymerizable compound handling device 70 side is not only in the reaction vessel 16 but also in the separation tower 61, the condenser 51, and the distillation tank. It may be provided in 62 or in the capacitor 63 for protecting the decompression device. Thereby, also in the line in the distillation tank 62 or the decompression device 64 from the reaction container 16, superposition | polymerization of the easily polymerizable compound 14 can be prevented efficiently.

  Examples of the reaction handled by the reaction apparatus include addition reaction of α, β-unsaturated carboxylic acid and cyclic ether such as ethylene oxide and propylene oxide.

  In the above-described method, the compound 34 having a polymerization stabilizing action may be introduced into the easily polymerizable compound handling apparatus 20 in a lump before handling the easily polymerizable compound 14 (for example, before the reaction), It may be introduced by dividing into several times. Moreover, you may introduce | transduce continuously during the handling (for example, during reaction) of the easily polymerizable compound 14, and may introduce | transduce intermittently.

  In addition, the polymerization inhibitor introduction apparatus (for example, the polymerization inhibitor introduction apparatus 40) used in the above-described method increases the efficiency of introduction and workability of the compound 34 having a polymerization stabilizing action into the easily polymerizable compound handling apparatus 20. In order to increase, in addition to the heating means 5 and the stirring device 1 as described above, a decompression device, a solvent introduction line, a withdrawal line, and the like may be provided. The polymerization inhibitor introducing device 40 includes the compound 34 having a polymerization stabilizing action to be used and the physical property values (for example, boiling point, vapor pressure, decomposition temperature, etc.) of the gaseous decomposition product of the compound 34 having a polymerization stabilizing action, What is necessary is just to select suitably by the quantity required in order to suppress superposition | polymerization of the easily polymerizable compound 14. FIG.

  In the above description, the case where the easily polymerizable compound 14 is handled as a liquid and a gas has been described. However, the present invention is not limited to this. It may be a case where it is handled as a solid.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

〔Example〕
Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to these examples.

[Production example]
In a SUS-316 type autoclave with a stirrer having a capacity of 1.5 liters, 572 g of acrylic acid, 3.8 g of new chromium acetate as a catalyst, and hydroquinone monomethyl ether (hereinafter referred to as MQ) as a polymerization inhibitor (a compound having a polymerization stabilizing action) ) 0.48 g was charged. After raising the temperature inside the autoclave to 50 ° C., the inside thereof was replaced with nitrogen gas, so that the oxygen concentration was 3% by volume and the internal pressure was 0.05 MPaG (gauge pressure). Thereafter, 367 g of ethylene oxide was fed into the autoclave at a constant speed over 4 hours. During this time, the reaction temperature was maintained at 50 ° C. After completion of the ethylene oxide supply, the reaction temperature was raised to 70 ° C. to continue the reaction. By continuing the reaction for 3 hours, the amount of unreacted acrylic acid was 0.10% by weight or less.

[Comparative Example 1]
To 900 g of the reaction solution obtained in the production example, 2.0 g of salicylic acid (SAL) was added, the mixture was charged into a 1.0 liter SUS-316 distillation kettle, the kettle was heated in an oil bath, and batch distillation was performed. Went. Distillation was carried out over 4 hours while introducing a distillation kettle internal pressure of 4 hPa, a liquid temperature of 70 to 85 ° C., and introducing 250 mL of air per hour into the distillation kettle. By this distillation, 786 g of hydroxyethyl acrylate and 111 g of distillation residue were obtained as target products. However, some polymer was confirmed in the liquid condensing part in the distillation apparatus.

[Comparative Example 2]
In Comparative Example 1, instead of adding 2.0 g of salicylic acid (SAL) to 900 g of the reaction solution obtained in the production example, 0.50 g of hydroquinone (HQ) and 2.0 g of SAL were added to 900 g of the reaction solution obtained in the production example. The same operation as in Comparative Example 1 was performed except that it was added. By this distillation, 786 g (containing 10 ppm of HQ) of pale yellow hydroxyethyl acrylate was obtained. The HQ concentration of hydroxyethyl acrylate was determined by gas chromatography.

[Comparative Example 3]
A gasification tank (polymerization inhibitor introduction apparatus) is connected to the gas phase portion of the apparatus used in Comparative Example 1, and after the polymerization inhibitor is gasified in advance in the gasification tank, the polymerization inhibitor gas is removed from the distillation kettle. Distillation was carried out in the same manner as in Comparative Example 1 except that it was introduced into the phase part. The operation of the gasification tank (capacity: 100 mL) was carried out by dissolving 5.0 g of HQ in 50 g of hydroxyethyl acrylate and continuously introducing steam generated at 10 hPa and a liquid temperature of 100 ° C. into the gas phase part of the distillation kettle. It was. By this operation, the residual liquid in the gasification tank turned yellow, and the amount of HQ in the residual liquid in the gasification tank at this time was 0.40 g.

  By this distillation, 788 g of pale yellow hydroxyethyl acrylate (containing 10 ppm of HQ) was obtained.

[Comparative Example 3-2]
After the operation of Comparative Example 3, 2.0 g of hydroxyethyl acrylate and 0.01 g of HQ were added to the gasification layer, and the contents (residual liquid) of the distillation kettle were replaced with the reaction liquid obtained in the production example, and distillation was performed again. went. By this distillation, pale yellow hydroxyethyl acrylate (containing 8 ppm of HQ) was obtained.

[Comparative Example 4]
Distillation was carried out with the apparatus used in Comparative Example 3. The operating conditions of the gasification tank were such that 0.50 g of HQ was dissolved in 50 g of hydroxyethyl acrylate, and steam generated at 10 hPa and a liquid temperature of 60 ° C. was continuously introduced into the gas phase section of the distillation kettle. After this operation, there was no particular change in the appearance of the residual liquid in the gasification tank, and the amount of HQ in the residual liquid in the gasification tank was 0.50 g.

  By this distillation, 786 g of colorless hydroxyethyl acrylate (HQ not detected) was obtained. However, some polymer was confirmed in the liquid condensing part in the distillation apparatus.

[Comparative Example 5]
Distillation was carried out with the apparatus used in Comparative Example 3. The operating conditions of the gasification tank were such that 0.50 g of HQ was dissolved in 50 g of the distillation residue obtained in Comparative Example 1, and steam generated at 10 hPa and a liquid temperature of 100 ° C. was continuously introduced into the gas phase part of the distillation kettle. After this operation, the amount of HQ in the residual liquid in the gasification tank was 0.30 g.

  By this distillation, 786 g (containing 10 ppm of HQ) of pale yellow hydroxyethyl acrylate was obtained.

[Comparative Example 5-2]
After the operation of Comparative Example 5, 0.01 g of HQ was added to the gasification layer, and the contents (residual liquid) of the distillation kettle were replaced with the reaction liquid obtained in Production Example, and distillation was performed again. By this distillation, 786 g (containing 6 ppm of HQ) of pale yellow hydroxyethyl acrylate was obtained.

[Comparative Example 6]
Distillation was carried out with the apparatus used in Comparative Example 3. The operating conditions of the gasification tank were such that 0.50 g of HQ was dissolved in 50 g of the distillation residue obtained in Comparative Example 1, and the steam generated at a liquid temperature of 60 ° C. was continuously introduced into the gas phase part of the distillation kettle. After this operation, the amount of HQ in the residual liquid in the gasification tank was 0.49 g.

  By this distillation, 786 g of colorless hydroxyethyl acrylate (HQ not detected) was obtained. However, some polymer was confirmed in the liquid condensing part in the distillation apparatus.

[Example 1]
Distillation operation was carried out using the apparatus used in Comparative Example 3. The operating conditions of the gasification tank were as follows: 0.50 g of HQ was dissolved in 50 g of hydroxyethyl acrylate, and air generated at 900 ml / h was introduced into the gas phase part of the distillation kettle at 10 hPa and a liquid temperature of 60 ° C. Continued to introduce. After this operation, there was no particular change in the appearance of the residual liquid in the gasification tank, and the amount of HQ in the residual liquid in the gasification tank was 0.49 g.

  By this distillation, 788 g of colorless hydroxyethyl acrylate (containing 10 ppm of HQ) was obtained.

[Example 1-2]
After the operation of Example 1, 2.0 g of hydroxyethyl acrylate and 0.01 g of HQ were added to the gasification layer, and the contents (residual liquid) of the distillation kettle were replaced with the reaction liquid obtained in the production example, and distillation was performed again. went. By this distillation, 788 g of colorless hydroxyethyl acrylate (containing 10 ppm of HQ) was obtained. After these operations, no polymer was confirmed in the distillation apparatus.

[Example 2]
Distillation operation was carried out using the apparatus used in Comparative Example 3. The operating conditions of the gasification tank were as follows: 0.50 g of HQ was dissolved in 50 g of the distillation residue obtained in Comparative Example 1, and air generated at 900 ml / h was introduced into the distillation kettle at 10 hPa and a liquid temperature of 60 ° C. Continued to be introduced into the gas phase. After this operation, the amount of HQ in the residual liquid in the gasification tank was 0.48 g. By this distillation, 786 g (containing 10 ppm of HQ) of colorless hydroxyethyl acrylate was obtained. After these operations, no polymer was confirmed in the distillation apparatus.

[Example 2-2]
After the operation of Example 2, 0.01 g of HQ was added to the gasification layer, and the contents (residual liquid) of the distillation kettle were replaced with the reaction liquid obtained in Production Example, and distillation was performed again. By this distillation, 786 g (containing 10 ppm of HQ) of colorless hydroxyethyl acrylate was obtained. After these operations, no polymer was confirmed in the distillation apparatus.

[Comparative Example 7]
900 g of hydroxypropyl acrylate and 0.40 g of MQ were charged into a 1.0-liter SUS-316 distillation kettle, and the distillation kettle was heated in an oil bath to perform batch distillation. Distillation was carried out over 3 hours while introducing an internal pressure of 4 hPa in the distillation kettle, a liquid temperature of 70 to 85 ° C., and further introducing 250 mL of air into the kettle. By this distillation, 675 g of colorless hydroxypropyl acrylate (containing MQ 60 ppm) was obtained. However, some polymer was confirmed in the liquid condensing part in the distillation apparatus.

Example 3
A gasification tank (polymerization inhibitor introduction device) was connected to the gas phase portion of the apparatus used in Comparative Example 7, and 0.18 g of MQ was charged into 900 g of hydroxypropyl acrylate in a distillation kettle, and batch distillation was performed in the same manner as in Comparative Example 7. It was. The operation of the gasification tank (capacity 100 mL) was carried out by dissolving 5.0 g of MQ in 45.0 g of hydroxypropyl acrylate and distilling steam generated at 10 hPa and a liquid temperature of 60 ° C. while introducing air at 900 mL / h. This was done by continuing to introduce into the gas phase part of the kettle. By this distillation, 675 g of colorless hydroxypropyl acrylate (containing MQ 60 ppm) was obtained. No polymer was confirmed in the distillation apparatus.

[Example 3-2]
Batch distillation was performed in the same manner as in Example 3 except for the amount of air introduced into the gasification tank. Air was introduced at 900 mL / h when the outflow amount was 0 to 225 g, 770 mL / h between 225 and 450 g, and 530 mL / h between 450 and 675 g. By this distillation, colorless hydroxypropyl acrylate (containing 50 ppm of MQ) was obtained. No polymer was confirmed in the distillation apparatus.

[Comparative Example 8]
Hydroxyethyl methacrylate (900 g), N-nitrosophenylhydroxylamine (0.02 g), and MQ (0.05 g) were charged into a 1.0-liter SUS-316 distillation kettle, the distillation kettle was heated in an oil bath, and batch distillation (over 3 hours) Distillation tank internal pressure: 4 hPa, liquid temperature: 70 to 85 ° C., air introduction speed: 250 mL / h) were performed to obtain 675 g of hydroxyethyl methacrylate. The concentration of N component when the distillate is 100 g (measured with a trace total nitrogen analyzer (manufactured by Mitsubishi Kasei, TN-05)) is 2 ppm, the concentration of N component at 300 g is 0.5 ppm, and the concentration of N component is 600 g. Was less than 0.5 ppm. However, some polymer was confirmed in the liquid condensing part in the distillation apparatus.

Example 4
A gasification tank (polymerization inhibitor introduction device) is connected to the gas phase part of the apparatus used in Comparative Example 8, and 0.05 g of MQ is charged into 900 g of hydroxyethyl methacrylate in a distillation kettle, and batch distillation is performed in the same manner as in Comparative Example 8. It was. The operation of the gasification tank (capacity 100 mL) was carried out by dissolving 0.02 g of N-nitrosophenylhydroxylamine in 45 g of hydroxyethyl methacrylate and introducing air at 90 mL / h, and steam generated at 10 hPa and a liquid temperature of 40 ° C. Was continued by introducing it into the gas phase part of the still. By this distillation, 675 g of colorless hydroxyethyl methacrylate was obtained. The N concentration when the distillate was 100 g, 300 g, and 600 g was 1 ppm. After these operations, no polymer was confirmed in the distillation apparatus.

Example 5
Propylene was oxidized using a normal gas phase catalytic oxidation method, and crude acrylic acid was obtained through the steps of water collection, toluene azeotropic dehydration, and light boiling separation. The crude acrylic acid contained 20 ppm dibutyldithiocarbamate (II) salt, 50 ppm MQ, and 100 ppm phenothiazine as stabilizers. 800 g of this crude acrylic acid was added to a 1.0 liter SUS-316 distillation kettle equipped with a separation tower (the separation tower was equipped with a packing, and a gasification tank (polymerization inhibitor) was placed at the top of the separation tower. Introducing equipment) is connected).

  Distillation with the above distillation kettle was performed for 6 hours while introducing a liquid temperature at the bottom of the column at 60 ° C. and a pressure of 40 hPa while introducing air into the distillation kettle at 700 mL / h. A part of the distillate in which 10 ppm of MQ was dissolved with respect to the amount of crude acrylic acid introduced was refluxed from the top of the column at a reflux ratio of 0.3. The operating conditions of the gasification tank were as follows: 0.02 g of N-nitrosophenylhydroxylamine was dissolved in 50 g of crude acrylic acid, and air generated at 60 hPa and a liquid temperature of 40 ° C. was introduced into the distillation apparatus while introducing air at 100 mL / h. Continued to be introduced. By this distillation, 600 g of acrylic acid was obtained.

  In addition, the N content concentration in the obtained acrylic acid was 1 ppm in any of the outflow amounts of 100 g, 300 g, and 600 g. Moreover, the polymer was not confirmed in the distillation apparatus after these operations.

[Comparative Example 9]
The same operation as in Example 5 except that the gasification tank (polymerization inhibitor introduction device) is not connected to the top of the separation tower and 0.02 g of N-nitrosophenylhydroxylamine is added as an initial charge. And 600 g of acrylic acid was obtained. The N concentration in the obtained acrylic acid was 2 ppm when the effluent amount was 100 g, and less than 0.5 ppm when 300 g and 600 g. Moreover, some polymer was confirmed in the distillation apparatus after these operations.

  From the results of the above examples, in the examples in which the compound having a polymerization stabilizing action is introduced into the apparatus that handles the easily polymerizable compound together with the non-condensable gas (air) in the gaseous state, the polymerization inhibitor introducing apparatus is provided. Compared to Comparative Examples 1, 2, 7, and 8 that were not used, the polymerization suppression effect was excellent. In addition, Comparative Examples 3, 3-2, 4, 5, 5-2, and 6 in which a polymerization inhibitor introduction apparatus is used but a compound having a polymerization stabilizing action together with a non-condensable gas (air) is not introduced. In comparison, the stabilizer remaining rate was high. That is, it was confirmed that the polymerization can be suppressed at a lower cost because the loss of the compound having a polymerization stabilizing action is small.

  Moreover, even if it was a case where a distillation residue was used instead of the hydroxyethyl acrylate used with a gasification tank, it has confirmed similarly that superposition | polymerization can be suppressed (refer Example 2 and the comparative example 5).

  In addition, it is thought that the difference of the effect of the comparative example 7 and Example 3 and 3-2 originates in the vapor | steam amount of the compound which has the superposition | polymerization stabilization effect | action which generate | occur | produces from a distillation bottom changing in the case of batch distillation. It is done. That is, in Comparative Example 7, a polymer is generated at an early stage where the concentration of the compound having a polymerization stabilizing action is low, but in Examples 3 and 3-2, since a polymerization inhibitor introducing device is provided, It is considered that the vapor amount of the compound having a polymerization stabilizing action was stable, and no polymer was generated. In Example 3-2, no polymer was generated even when the amount of the compound having a polymerization stabilizing effect in the latter half of distillation was reduced.

  In Comparative Examples 8 and 9, a large amount of N was distilled at the beginning of distillation and N was not distilled in the latter half of the distillation, whereas in Examples 4 and 5, N was almost constant during the distillation period. It was confirmed that a large amount was distilled out.

  The method for preventing polymerization of an easily polymerizable compound of the present invention can efficiently prevent polymerization of the easily polymerizable compound in the gas phase. For this reason, it can apply widely to the field which handles easily polymerizable compounds, such as a reaction apparatus and a distillation apparatus.

It is a schematic diagram which shows schematic structure of the superposition | polymerization prevention easily polymerizable compound handling apparatus used with the superposition | polymerization prevention method concerning this Embodiment. It is a schematic diagram which shows schematic structure of an example of the easily polymerizable compound handling apparatus in the polymerization-inhibiting easily polymerizable compound handling apparatus which concerns on this Embodiment.

Explanation of symbols

14 Easily polymerizable compounds 20 Easily polymerizable compounds handling equipment (Equipment for handling easily polymerizable compounds)
34 Compound with polymerization stabilizing action 70 Easily polymerizable compound handling equipment (Equipment for handling easily polymerizable compounds)

Claims (2)

A device that handles a readily polymerizable compound by vaporizing a compound having a polymerization stabilizing effect that is liquid or solid at normal temperature and normal pressure by introducing a non-condensable gas and diluting the compound diluted in the non-condensable gas. A method for preventing polymerization of an easily polymerizable compound, which is introduced into a gas phase in the inside . The method for preventing polymerization of an easily polymerizable compound according to claim 1, wherein the compound is heated to a temperature not lower than 0 ° C and not higher than a temperature lower by 10 ° C than a liquid temperature in an apparatus handling the easily polymerizable compound. .

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