Method for producing (meth) acrylate having vinyl ether group

Abstract

A method for producing a (meth) acrylate having a vinyl ether group. [Problem] To provide a method for efficiently preventing polymerization of a gas phase portion when producing a (meth) acrylate having a vinyl ether group by a transesterification reaction. [Solution] The present invention is a method for producing a (meth) acrylate having a vinyl ether group, characterized by comprising a step for obtaining a (meth) acrylate having a vinyl ether group by transesterification using a starting material solution containing a starting material (meth) acrylate, a hydroxyl group-containing vinyl ether compound, a catalyst, N-nitrosoamine (salt), and water, in the raw material solution, the mass ratio of water is 1500 ppm or more and 5 mass% or less, and the molar ratio of water to N-nitrosoamine (salt) is 40 or more and 1100 or less.

Description

Technical Field

[0001] The present invention relates to a method for producing a (meth)acrylate having a vinyl ether group. More specifically, the present invention relates to a method for producing a (meth)acrylate having a vinyl ether group which is used as a raw material for various industrial products. Background Art

[0002] (Meth)acrylates having a vinyl ether group are easily polymerizable compounds having a (meth)acryloyl group containing a free radical polymerizable double bond and being able to be easily polymerized using heat, light, ultraviolet rays, etc. Therefore, they are very useful as monomers for polymers, and various methods for producing them have been studied. As one of the reaction processes, a process for producing (meth)acrylates having a vinyl ether group by causing a raw material (meth)acrylate to undergo an ester exchange reaction with a hydroxyl-containing vinyl ether compound is known. In this reaction process, since both the raw material and the target product are easily polymerizable compounds, various methods for preventing them from polymerizing have been studied.

[0003] For example, it is disclosed that N-nitrosoamines are added to acrylate or methacrylate to prevent popcorn polymerization of acrylate or methacrylate (see, for example, Patent Document 1).

[0004] In addition, for example, the following production method is disclosed, which is characterized in that it is a method for producing a (meth)acrylate having an ether group from a reaction raw material containing a (meth)acrylate and a hydroxyl-containing ether compound, and the production method includes the following steps: reacting the reaction raw material in the presence of a specific N-nitrosophenylhydroxylamine salt, a phosphite and / or a thioether, and a primary antioxidant (for example, refer to Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 49-125315

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-197236 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] The above-mentioned N-nitrosoamines do not have the effect of preventing polymerization by themselves, but the decomposition products generated by heat, acid, etc. during the reaction exert the effect of preventing polymerization, especially in the gas phase of the reaction system. Here, in the invention described in Patent Document 2, the N-nitrosoamines decomposed by the end of the reaction account for about 30% of the total amount, and most of them remain in the system without being decomposed, so there are problems from the viewpoints of efficiency and economy.

[0011] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a method for efficiently preventing polymerization in a gas phase when producing a (meth)acrylic acid ester having a vinyl ether group by an ester exchange reaction.

[0012] Solutions for solving problems

[0013] The present inventors have conducted various studies on methods for efficiently preventing polymerization of a gas phase when producing a (meth)acrylic acid ester having a vinyl ether group by an ester exchange reaction, and focused on the decomposition rate of N-nitrosoamine (salt). The present inventors have found that in a method for producing a (meth)acrylic acid ester having a vinyl ether group, the present inventors use a raw material solution containing a raw material (meth)acrylic acid ester, a hydroxyl-containing vinyl ether compound, a catalyst, an N-nitrosoamine (salt) and water, and obtain the (meth)acrylic acid ester having a vinyl ether group by an ester exchange reaction, when the mass ratio of water in the raw material solution is set to 1500 ppm or more and 5% by mass or less, and when the molar ratio of water to the N-nitrosoamine (salt) is set to 40 or more and 1100 or less, the decomposition rate of the N-nitrosoamine (salt) can be increased, and polymerization of the gas phase can be more efficiently prevented. The present inventors have found that the above-mentioned problems can be perfectly solved, and have completed the present invention.

[0014] That is, the present invention (1) is a method for producing a (meth)acrylate having a vinyl ether group, characterized in that it includes the following steps: using a raw material solution containing a raw material (meth)acrylate, a hydroxyl-containing vinyl ether compound, a catalyst, an N-nitrosoamine (salt) and water, to obtain a (meth)acrylate having a vinyl ether group by an ester exchange reaction, wherein the mass ratio of water in the raw material solution is 1500 ppm or more and 5 mass% or less, and the molar ratio of water to the N-nitrosoamine (salt) is 40 or more and 1100 or less.

[0015] The present invention (2) is a method for producing a (meth)acrylate having a vinyl ether group according to the present invention (1), characterized in that the above-mentioned hydroxyl-containing vinyl ether compound is diethylene glycol monovinyl ether, and the above-mentioned (meth)acrylate having a vinyl ether group is 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.

[0016] The present invention (3) is a method for producing a (meth)acrylate having a vinyl ether group according to the present invention (1) or (2), characterized in that the N-nitrosoamine (salt) is N-nitrosophenylhydroxylamine (salt).

[0017] Effects of the Invention

[0018] The method for producing a (meth)acrylate having a vinyl ether group of the present invention includes the above-mentioned configuration and can effectively prevent polymerization of the (meth)acryloyl group in the gas phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing an example of a production apparatus for carrying out the production method of the present invention.

[0020] Figure 2 This is a graph showing the correlation between water concentration and NPH decomposition rate.

[0021] Description of Reference Numerals

[0022] 1: Raw material solution

[0023] 2: Waste oil

[0024] 3: Finished product (rough product)

[0025] 11: Reaction tank

[0026] 21: First distillation tower

[0027] 31: Second distillation column

[0028] 71, 72, 81: Pipeline DETAILED DESCRIPTION

[0029] The present invention is described in detail below.

[0030] In addition, the preferred aspects of the present invention described below may be combined with two or more of the preferred aspects of the present invention.

[0031] <Step of Obtaining (Meth) Acrylic Acid Ester Having Vinyl Ether Group>

[0032] The production method of the present invention includes the following steps: using a raw material solution containing a raw material (meth) acrylic acid ester, a hydroxyl-containing vinyl ether compound, a catalyst, an N-nitrosoamine (salt) and water, obtaining a (meth) acrylic acid ester having a vinyl ether group by an ester exchange reaction, wherein the mass ratio of water in the raw material solution is 1500 ppm or more and 5 mass % or less, and the molar ratio of water to the N-nitrosoamine (salt) is 40 or more and 1100 or less. In this specification, the step of obtaining a (meth) acrylic acid ester having a vinyl ether group by an ester exchange reaction is also referred to as a reaction step.

[0033] In addition, in this specification, (meth)acrylate means acrylate and / or methacrylate, and (meth)acryloyl means acryloyl and / or methacryloyl.

[0034] (water)

[0035] In the production method of the present invention, the raw material solution contains 1500 ppm or more and 5% or less of water in 100% by mass of the raw material solution, and contains 40 or more and 1100 or less of water in terms of the molar ratio of water to N-nitrosoamine (salt). By containing 1500 ppm or more and 40 or more of water in terms of the molar ratio, the decomposition rate of N-nitrosoamine (salt) becomes very high, and the decomposed product functions as an anti-polymerization agent, which can fully prevent gas phase polymerization. In addition, it is believed that if the mass ratio of water is 5% or less and the molar ratio is 1100 or less, it is possible to prevent the effect from being saturated.

[0036] From the viewpoint of more fully preventing the gas phase polymerization in the reaction process, the mass ratio of the above-mentioned water is preferably more than 2000ppm, more preferably more than 2500ppm, and particularly preferably more than 3000ppm. In addition, from the viewpoint of further preventing the effect from being saturated, the mass ratio of water is preferably below 4% by mass, and particularly preferably below 3% by mass.

[0037] The mass ratio and molar ratio of the above-mentioned water refer to the mass ratio or molar ratio of water in the raw material solution supplied to the reaction process. The raw material solution can be put into a reaction device such as a reaction tank at once, or it can be supplied to the reaction device continuously or intermittently. In addition, raw materials, catalysts, water, etc. can be supplied to the reaction device during the reaction period. For example, it is one of the preferred embodiments of the present invention that water is supplied to the reaction device during the reaction period. The raw materials, catalysts, water, etc. supplied during the reaction period are also regarded as part of the raw material solution.

[0038] From the viewpoint of more fully preventing gas phase polymerization in the reaction step, the molar ratio of water to N-nitrosoamine (salt) is preferably 60 or more, more preferably 75 or more. From the viewpoint of further preventing saturation of the effect, the molar ratio of water is preferably 900 or less, more preferably 800 or less.

[0039] The above-mentioned molar ratio of water refers to the molar ratio of water in the raw material solution supplied to the reaction step to the N-nitrosoamine (salt).

[0040] It should be noted that the water may be water previously contained in the raw materials or preparations (water derived from the raw materials, etc.), water added (mixed) to the raw materials, etc., or both. As described later, it is preferred that at least a portion of the water is water added to the raw materials, etc. As water added to the raw materials, etc., tap water (sewage water), distilled water, purified water, pure water, ion exchange water, industrial pure water, etc. may be cited, and one or more of them may be used.

[0041] (N-nitrosoamine (salt))

[0042] The above-mentioned N-nitrosoamine (salt) is a compound having a group represented by O=NN=. It should be noted that the "=" on the right end of O=NN= may be one double bond or two single bonds. Examples of the above-mentioned N-nitrosoamine (salt) include, for example, N-nitrosoamine-N-methylaniline, N-nitroso-N,N'-dimethylamine, N-nitroso-N-methyl-p-toluenesulfonamide, N-nitrosophenylhydroxylamine (salt) (NPH), o-nitrosoresorcinol monomethyl ether, N-nitroso-N-methylcarbamate, p-nitrosodiphenylamine, α-nitroso-β-naphthol, M-nitroso-N-methylβ-aminonaphthalene, 5-nitroso-8-hydroxyquinoline, β-nitroso-α-naphthol, N-nitrosophenylhydroxylamine, and the like, and one or more of them may be used. It should be noted that the above-mentioned N-nitrosoamine (salt) refers to N-nitrosoamine and / or N-nitrosoamine salt, which may be in the form of anions in the raw material solution.

[0043] Among them, the above-mentioned N-nitrosoamine (salt) is preferably NPH.

[0044] The above-mentioned NPH is a compound represented by the following general formula (1).

[0045]

[0046] (In the formula, M represents a metal atom, an ammonium group or a hydrogen atom. n represents a positive number equal to the valence of M. The dotted line connecting M and the oxygen atom represents that M can be optionally coordinated to the oxygen atom.)

[0047] M in the general formula (1) above represents a metal atom, an ammonium group or a hydrogen atom, and examples of the metal atom include aluminum, copper, iron (III), tin, zinc, magnesium, titanium, cobalt, nickel, zirconium, vanadium (V), niobium, tantalum, phosphorus, bismuth (III), etc. Among these, the above M is preferably aluminum, zinc, tin, phosphorus, iron (III), and an ammonium group, more preferably aluminum, zinc, tin, and an ammonium group, and even more preferably aluminum and an ammonium group.

[0048] The NPH is particularly preferably, for example, N-nitrosophenylhydroxylamine ammonium salt (NPHN).

[0049] The N-nitrosoamine (salt) is preferably 10 ppm or more, more preferably 50 ppm or more, and further preferably 100 ppm or more in 100% by mass of the raw material solution. Thus, the polymerization of the raw materials and the target product can be more fully prevented in the reaction process. In addition, the mass ratio of the N-nitrosoamine (salt) is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 1000 ppm or less. Thus, the economic efficiency is excellent, and the excess N-nitrosoamine (salt) residue, the deterioration of the polymerizability or color tone of the target product can be more fully prevented.

[0050] In addition, when two or more N-nitrosoamines (salts) are used, the above-mentioned mass ratio is the mass ratio of the total.

[0051] The mass ratio of the N-nitrosoamine (salt) in the reaction step of the present invention is preferably 2 ppm to 5 mass % relative to 100 mass % of the hydroxyl-containing vinyl ether compound as the reaction raw material, more preferably 10 ppm to 1 mass %, further preferably 20 to 5000 ppm, and particularly preferably 100 to 2000 ppm.

[0052] (Raw material (meth)acrylate)

[0053] The raw material (meth)acrylate is not particularly limited as long as it can undergo an ester exchange reaction with a hydroxyl-containing vinyl ether compound to produce a (meth)acrylate having a vinyl ether group as the target product. One or more of them can be used, and the compound represented by the following general formula (2) is preferred.

[0054] CH2=CR 1 —COO-R 3 (2)

[0055] (Where R 1 represents a hydrogen atom or a methyl group. 3 represents an organic group. )

[0056] As R in the above general formula (2) 3 The organic group shown is not particularly limited, and is preferably, for example, a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, or an optionally substituted aromatic group having 6 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms.

[0057] Examples of the (meth)acrylate represented by the general formula (2) include lower alkyl (meth)acrylates (the alkyl group of the alkyl ester has 1 to 4 carbon atoms) such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, and tert-butyl (meth)acrylate. Among these, methyl acrylate (AM), methyl methacrylate, ethyl acrylate, and ethyl methacrylate are preferred, and methyl acrylate (AM) and ethyl acrylate are more preferred.

[0058] The raw material (meth) acrylate is preferably 10% by mass or more in 100% by mass of the raw material solution, more preferably 20% by mass or more, further preferably 30% by mass or more, further preferably 40% by mass or more, and particularly preferably 50% by mass or more. In addition, the mass ratio of the raw material (meth) acrylate is preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 70% by mass or less, and particularly preferably 65% ​​by mass or less.

[0059] In addition, when two or more types of the above-mentioned raw material (meth)acrylate are used, the above-mentioned mass ratio is the mass ratio of the total.

[0060] (Hydroxy-containing vinyl ether compound)

[0061] The hydroxyl-containing vinyl ether compound is not particularly limited as long as it contains a hydroxyl group and can undergo an ester exchange reaction with the raw material (meth)acrylate to produce the target product, a (meth)acrylate having a vinyl ether group. One or more of them can be used, and among them, the hydroxyl-containing vinyl ether compound represented by the following general formula (3) is preferred.

[0062] CH2=CH-OR 2 -OH (3)

[0063] (Where R 2 represents an organic group. )

[0064] In the hydroxyl-containing vinyl ether compound represented by the general formula (3), R in the general formula (3) is 2 The organic group shown is not particularly limited, and examples thereof include a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms, an alkylene group having 2 to 20 carbon atoms and having an oxygen atom in the structure via an ether bond and / or an ester bond, and an optionally substituted aromatic group having 6 to 11 carbon atoms. Among these, an alkylene group having 2 to 6 carbon atoms and an alkylene group having 4 to 10 carbon atoms and having an oxygen atom in the structure via an ether bond are preferred.

[0065] Examples of the hydroxyl-containing vinyl ether compound represented by the general formula (3) include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxyisopropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 2-hydroxybutyl vinyl ether, 3-hydroxyisobutyl vinyl ether, 2-hydroxyisobutyl vinyl ether, 1-methyl-3-hydroxypropyl vinyl ether, 1-methyl-2-hydroxypropyl vinyl ether, 1-hydroxymethylpropyl vinyl ether, 4-hydroxycyclohexyl vinyl ether, 1,6-hexanediol monovinyl ether, 1,4-cyclohexanedimethanol monovinyl ether, 1,3 -cyclohexanedimethanol monovinyl ether, 1,2-cyclohexanedimethanol monovinyl ether, p-phenylenedimethanol monovinyl ether, isophenylenedimethanol monovinyl ether, o-phenylenedimethanol monovinyl ether, diethylene glycol monovinyl ether (DEGV), triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, pentaethylene glycol monovinyl ether, oligoethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, dipropylene glycol monovinyl ether, tripropylene glycol monovinyl ether, tetrapropylene glycol monovinyl ether, pentapropylene glycol monovinyl ether, oligopropylene glycol monovinyl ether, polypropylene glycol monovinyl ether, ethylene glycol-propylene glycol copolymer monovinyl ether, etc., and one or more of them can be used.

[0066] The hydroxyl-containing vinyl ether compound represented by the general formula (3) is preferably 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxyisopropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxycyclohexyl vinyl ether, 1,6-hexanediol monovinyl ether, 1,4-cyclohexanedimethanol monovinyl ether, DEGV, triethylene glycol monovinyl ether, and dipropylene glycol monovinyl ether. DEGV is more preferred.

[0067] The above-mentioned hydroxyl-containing vinyl ether compound is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 35% by mass or more in 100% by mass of the above-mentioned raw material solution. In addition, the mass proportion of the above-mentioned hydroxyl-containing vinyl ether compound is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0068] In addition, when two or more hydroxyl-containing vinyl ether compounds are used, the above-mentioned mass ratio is the total mass ratio thereof.

[0069] The molar ratio of the raw material (meth) acrylic acid ester and the hydroxyl-containing vinyl ether compound in the above reaction step can be appropriately set according to the combination of the types of the raw material (meth) acrylic acid ester and the hydroxyl-containing vinyl ether compound, and is preferably 20 / 1 to 1 / 5. From the viewpoint of yield and economic efficiency, the blending ratio in this range is preferred. It is more preferably 15 / 1 to 1 / 3, and further preferably 10 / 1 to 1 / 2. It is particularly preferably 5 / 1 to 1 / 1.

[0070] (catalyst)

[0071] The above-mentioned catalyst is not particularly limited as long as it has the function of accelerating the transesterification reaction, and examples thereof include oxides such as calcium oxide, barium oxide, lead oxide, zinc oxide, and zirconium oxide; hydroxides such as potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, thallium hydroxide, tin hydroxide, lead hydroxide, and nickel hydroxide; halides such as lithium chloride, calcium chloride, tin chloride, lead chloride, zirconium chloride, and nickel chloride; carbonates such as potassium carbonate, rubidium carbonate, cesium carbonate, lead carbonate, zinc carbonate, and nickel carbonate; hydrogen carbonates such as potassium hydrogen carbonate, rubidium hydrogen carbonate, and cesium hydrogen carbonate; phosphates such as sodium phosphate, potassium phosphate, rubidium phosphate, lead phosphate, zinc phosphate, and nickel phosphate; nitrates such as lithium nitrate, calcium nitrate, lead nitrate, zinc nitrate, and nickel nitrate; carboxylates such as lithium acetate, calcium acetate, lead acetate, zinc acetate, and nickel acetate; sodium methoxide, sodium ethoxide, potassium methoxide, and ethanol Alkoxy compounds such as potassium, potassium tert-butoxide, calcium methoxide, calcium ethoxide, barium methoxide, barium ethoxide, tetraethoxytitanium, tetrabutoxytitanium, and tetra(2-ethylhexyloxy)titanium; acetylacetonate complexes such as lithium acetylacetonate, zirconium acetylacetonate, zinc acetylacetonate, dibutoxytin acetylacetonate, and dibutoxytitanium acetylacetonate; quaternary ammonium alkoxides such as tetramethylammonium methoxide, tetramethylammonium tert-butoxide, and trimethylbenzylammonium ethoxide; dialkyltin compounds such as dimethyltin oxide, methylbutyltin oxide, dibutyltin oxide (DBTO), and dioctyltin oxide; distannoxanes such as bis(dibutyltin acetate) oxide and bis(dibutyltin laurate) oxide; and dialkyldicarboxylic acid tin salts such as dibutyltin diacetate and dibutyltin dilaurate (DBTL), and one or more of them can be used.

[0072] Among these catalysts, potassium carbonate, cesium carbonate, tetraethoxytitanium, tetrabutoxytitanium, tetra(2-ethylhexyloxy)titanium, zirconium acetylacetonate, DBTO, dioctyltin oxide, bis(dibutyltin acetate) oxide, bis(dibutyltin laurate) oxide, dibutyltin diacetate, and DBTL are preferably used. DBTO and DBTL are more preferred.

[0073] The catalyst is preferably present in an amount of 100 ppm or more, more preferably 500 ppm or more, and even more preferably 1000 ppm or more in 100% by mass of the raw material solution. In addition, the mass ratio of the catalyst is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less by mass.

[0074] In addition, when two or more of the above catalysts are used, the above mass ratio is the total mass ratio thereof.

[0075] The amount of the catalyst is not particularly limited and can be appropriately set. For example, it is preferably in the range of 0.0001 to 20 mol% relative to 100 mol% of the hydroxyl-containing vinyl ether compound. From the viewpoint of yield and economic efficiency, the amount of the catalyst is preferably in this range. It is more preferably 0.0003 to 15 mol%, further preferably 0.0005 to 10 mol%, and particularly preferably 0.001 to 5 mol%.

[0076] (Primary Antioxidant)

[0077] The above-mentioned raw material solution preferably further contains a primary antioxidant.

[0078] The primary antioxidant is not particularly limited as long as it is a primary antioxidant that can capture and decompose peroxy radicals gradually generated in the liquid phase of the reaction system in the reaction step of the present invention and inhibit the radical polymerization reaction associated with the peroxy radicals. Examples thereof include phenolic antioxidants such as hydroquinone, methoxyhydroquinone, hydroquinone monomethyl ether (MEHQ), benzoquinone, p-tert-butylcatechol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,4,6-tri-tert-butylphenol, 3,5-di-tert-butyl-4-hydroxytoluene (BHT), and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane (TPB); alkylated diphenylamine, N,N'-diphenyl-p-phenylenediamine, and phenothiazine (P TZ) and other aromatic amine antioxidants; 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine and other cyclic amine antioxidants; copper dithiocarbamate antioxidants such as dimethyl copper dithiocarbamate, diethyl copper dithiocarbamate, and dibutyl copper dithiocarbamate; N-oxyl antioxidants such as 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and esters of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl. As the primary antioxidant, among these, phenolic antioxidants and aromatic amine antioxidants are preferred. As such, an embodiment in which the primary antioxidant is a phenolic antioxidant and / or an aromatic amine antioxidant is also one of the suitable embodiments of the present invention.

[0079] As the primary antioxidant, more preferred are hydroquinone, MEHQ, 3,5-di-tert-butyl-4-hydroxytoluene, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and PTZ.

[0080] The primary antioxidant is preferably present in an amount of 100 ppm or more, more preferably 500 ppm or more, and even more preferably 1000 ppm or more in 100% by mass of the raw material solution. In addition, the mass ratio of the primary antioxidant is preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 5000 ppm or less.

[0081] In addition, when two or more primary antioxidants are used, the above-mentioned mass ratio is the total mass ratio thereof.

[0082] The amount of the primary antioxidant used in the reaction step of the present invention is preferably 2 ppm to 5 mass % relative to 100 mass % of the mass of the hydroxyl-containing vinyl ether compound as the reaction raw material. The amount of the primary antioxidant is preferably in this range from the viewpoint of yield, the viewpoint of inhibiting polymerization in the liquid phase of the reaction system, and the viewpoint of economic efficiency. The amount is more preferably 10 ppm to 3 mass %, further preferably 50 ppm to 1 mass %, and particularly preferably 100 ppm to 5000 ppm.

[0083] (Secondary Antioxidant)

[0084] The raw material solution may further contain phosphite and / or thioether.

[0085] The phosphite and / or thioether described above functions as a secondary antioxidant that decomposes peroxides gradually generated in the liquid phase of the reaction system in the reaction step of the present invention to suppress the polymerization reaction associated with the peroxides.

[0086] As the above-mentioned phosphite, specifically, triphenyl phosphite (TPP), tris (2,4-di-tert-butylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite (BPOP), diphenyl mono (tridecyl) phosphite, diphenyl monodecyl phosphite, dioctadecyl pentaerythritol diphosphite, trioleyl phosphite, etc. can be listed, and one or more of these can be used. Among these, TPP, tris (2,4-di-tert-butylphenyl) phosphite, BPOP, diphenyl mono (tridecyl) phosphite, diphenyl monodecyl phosphite are preferred, and TPP, tris (2,4-di-tert-butylphenyl) phosphite, BPOP are more preferred. TPP and tris (2,4-di-tert-butylphenyl) phosphite are particularly preferred.

[0087] Specific examples of the thioether include dilauryl 3,3'-thiodipropionate (TDPL), distearyl 3,3'-thiodipropionate, didodecyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, and pentaerythritol tetra(β-laurylthiopropionate). Of these, TDPL, distearyl 3,3'-thiodipropionate, didodecyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate are preferred, and TDPL and distearyl 3,3'-thiodipropionate are more preferred. TDPL is particularly preferred.

[0088] The raw material solution may contain a secondary antioxidant such as tris(2,4-di-tert-butylphenyl)phosphite (DBPP).

[0089] The secondary antioxidant is preferably 100 ppm or more, more preferably 500 ppm or more, and further preferably 1000 ppm or more in 100% by mass of the raw material solution. In addition, the mass ratio of the secondary antioxidant is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 5000 ppm or less.

[0090] In addition, when two or more types of the above-mentioned secondary antioxidants are used, the above-mentioned mass ratio is the total mass ratio thereof.

[0091] In addition, the amount of the secondary antioxidant in the raw material solution in the reaction step of the present invention is preferably 2 ppm to 5 mass % relative to 100 mass % of the mass of the hydroxyl-containing vinyl ether compound as the reaction raw material. The amount of the secondary antioxidant is preferably in this range from the viewpoint of yield, the viewpoint of inhibiting polymerization in the liquid phase of the reaction system, and the viewpoint of economic efficiency. The amount is more preferably 10 ppm to 3 mass %, further preferably 50 ppm to 1 mass %, and particularly preferably 100 to 5000 ppm.

[0092] ((Meth)acrylate having a vinyl ether group as a target product)

[0093] In the production method of the present invention, a (meth)acrylate having a vinyl ether group is produced by subjecting a raw material (meth)acrylate to an ester exchange reaction with a hydroxyl-containing vinyl ether compound. Therefore, the obtained (meth)acrylate having a vinyl ether group is a compound synthesized by subjecting a compound selected from the raw material (meth)acrylate and the hydroxyl-containing vinyl ether compound to an ester exchange reaction. In this specification, the (meth)acrylate having a vinyl ether group as the target product is also referred to as a (meth)acrylate having a vinyl ether group.

[0094] In particular, when the raw material (meth)acrylate is a compound represented by general formula (2) and the hydroxyl-containing vinyl ether compound is a compound represented by general formula (3), the obtained (meth)acrylate having a vinyl ether group can be represented by the following general formula (4).

[0095] CH2=CR 1 -COO-R 2 -O-CH=CH2 (4)

[0096] (Where R 1 represents a hydrogen atom or a methyl group. 2 represents an organic group.) In this way, an embodiment in which the obtained (meth)acrylate having a vinyl ether group is a (meth)acrylate having a vinyl ether group represented by the general formula (4) is also one of the preferred embodiments of the present invention.

[0097] It should be noted that R in the general formula (4) 1 With R in the general formula (2) 1 Same, R in general formula (4) 2 With R in the general formula (3) 2 same.

[0098] Specific examples of the (meth)acrylate having a vinyl ether group represented by the general formula (4) include 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-vinyloxymethylpropyl (meth)acrylate, 2-methyl-3-vinyloxypropyl (meth)acrylate, 1,1-dimethyl-2-vinyloxyethyl ester, 3-vinyloxybutyl (meth)acrylate, 1-methyl-2-vinyloxypropyl (meth)acrylate, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexyl methyl (meth)acrylate, 3-vinyloxymethylcyclohexyl methyl (meth)acrylate, 2-vinyloxymethylcyclohexyl methyl (meth)acrylate, p-vinyloxymethylphenyl methyl (meth)acrylate, m-vinyloxymethylphenyl methyl (meth)acrylate, o-vinyloxymethylphenyl methyl (meth)acrylate, 2-(vinyloxymethyl)phenyl methyl (meth)acrylate 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, 2-(vinyloxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethyl)acrylate 2-(vinyloxyethoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxy) 2-(vinyloxyethoxy)ethyl acrylate, 2-(isopropoxyethoxy)ethyl (meth)acrylate, 2-(isopropoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropoxyethoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropoxyethoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropoxyethoxyethoxyethoxy)ethyl (meth)acrylate, polyethylene glycol monovinyl (meth)acrylate, polypropylene glycol monovinyl (meth)acrylate, etc., among which 2-(vinyloxyethoxy)ethyl acrylate (VEEA (registered trademark)) and 2-(vinyloxyethoxy)ethyl methacrylate (VEEM (registered trademark)) are preferred, and 2-(vinyloxyethoxy)ethyl acrylate is more preferred. 2-(vinyloxyethoxy)ethyl acrylate is particularly easy to polymerize, but by applying the production method of the present invention, polymerization in the gas phase can be effectively prevented. ,

[0099] The above reaction step is preferably carried out in an atmosphere in which the molecular oxygen concentration in the gas phase of the reaction system is 0.001 to 21% by volume. By setting the molecular oxygen concentration in the gas phase to such a range, the polymerization reaction in the above reaction step can be more efficiently prevented, and the (meth)acrylate having a vinyl ether group as the target product can be produced in high yield. The molecular oxygen concentration in the gas phase is more preferably 0.005 to 15% by volume, and further preferably 0.01 to 10% by volume.

[0100] As methods for adjusting the molecular oxygen concentration in the gas phase of the above-mentioned reaction system to the above-mentioned preferred range, the following methods can be listed: (a) a method of supplying a gas containing molecular oxygen such as molecular oxygen or air to the reaction container (where the steam is present) during the reaction to adjust the molecular oxygen concentration in the gas phase; (b) a method of supplying a gas containing molecular oxygen such as molecular oxygen or air and an inert gas such as nitrogen or argon to the reaction container (where the steam is present) during the reaction to adjust the molecular oxygen concentration in the gas phase; (c) a method of pre-mixing a gas containing molecular oxygen such as molecular oxygen or air and an inert gas such as nitrogen or argon and supplying the mixture to the reaction container (where the steam is present) during the reaction to adjust the molecular oxygen concentration in the gas phase, etc.

[0101] In addition, as a method for supplying molecular oxygen and / or a mixed gas containing molecular oxygen to the reaction system, it is sufficient to supply it continuously or intermittently to one or both of the liquid phase and the gas phase in the reaction system.

[0102] In addition, since the reaction in the above-mentioned reaction step is an ester exchange reaction, alcohol is by-produced as the reaction proceeds, and the by-produced alcohol is preferably removed to the outside of the reaction system.

[0103] As the method for removing the by-product alcohol, for example, a method of reacting under reduced pressure, a method of reacting using an azeotropic solvent, a method of reacting in the presence of an adsorbent, etc. can be cited. Among these, a method of reacting under reduced pressure, a method of reacting using an azeotropic solvent, etc. are preferred.

[0104] As the above-mentioned azeotropic solvent, there is no particular limitation as long as it does not hinder the transesterification reaction, and examples thereof include ethers such as diethyl ether, diisopropyl ether, and dibutyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as pentane, hexane, heptane, and cyclohexane; halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, and chlorobenzene. These azeotropic solvents can be used alone or in combination of two or more. In addition, the raw material (meth)acrylate used in excess can also be used as an azeotropic solvent.

[0105] The amount of the azeotropic solvent used is not particularly limited, for example, preferably 0 to 300% by mass of the mass of the hydroxyl-containing vinyl ether compound as a reaction raw material. From the viewpoint of yield and economic efficiency, the amount of the azeotropic solvent is preferably in this range. The amount is more preferably 1 to 200% by mass, further preferably 2 to 150% by mass, and particularly preferably 3 to 100% by mass.

[0106] The reaction temperature in the above-mentioned reaction step is not particularly limited, and is preferably above the boiling point or azeotropic temperature of the by-product alcohol. Specifically, it is preferably set to 40°C or above, more preferably 50°C or above, and further preferably 60°C or above. Thus, from the viewpoint that the by-product alcohol can be fully removed and the decomposition amount of N-nitrosoamine (salt) becomes more, the anti-polymerization effect of the gas phase becomes more significant. In addition, the reaction temperature is preferably set to 180°C or below, more preferably 140°C or below, and further preferably 100°C or below. Thus, from the viewpoint that the polymerization reaction of the easily polymerizable compound becomes difficult to proceed, the effect of preventing the polymerization of the gas phase becomes more significant. The reaction pressure is not particularly limited, and normal pressure, pressurization, and reduced pressure are all possible. As mentioned above, from the viewpoint of removing the by-product alcohol, reduced pressure is preferably used. In addition, the reaction time can be appropriately set in such a way that the reaction in the above-mentioned reaction step is completed, and can be set to 3 to 20 hours, for example.

[0107] The production method of the present invention may include other steps described later, as long as it includes the above-mentioned reaction step.

[0108] <Step of mixing raw materials etc. with water>

[0109] In the manufacturing method of the present invention, the water in the above-mentioned raw material solution can be only water (water derived from raw materials, etc.) pre-contained in at least one of the raw materials (meth) acrylic acid ester, hydroxyl-containing vinyl ether compound, catalyst, N-nitrosoamine (salt), and other preparations (also referred to as raw materials, etc. in this specification), and mixing the raw materials, etc. with water and controlling the mass ratio and molar ratio of water in the raw material solution to a specified range is one of the preferred modes in the manufacturing method of the present invention. That is, in the manufacturing method of the present invention, for example, before the process of obtaining a (meth) acrylic acid ester having a vinyl ether group, it is preferably included: a process of mixing at least one (raw material, etc.) selected from the group consisting of raw materials (meth) acrylic acid ester, hydroxyl-containing vinyl ether compound, catalyst and N-nitrosoamine (salt) with water. This mixing process can add water to the raw materials, etc., or add the raw materials, etc. to the water, or the raw materials, etc. and water can be respectively put into the reaction container. Thus, the mass ratio and molar ratio of water in the raw material solution can be appropriately adjusted. In the production method of the present invention, for example, during the step of obtaining the (meth)acrylate having a vinyl ether group, it is also preferred to further include a step of supplying water and / or raw materials to the liquid phase of the reaction system.

[0110] [Purification after the reaction step]

[0111] In the production method of the present invention, after the above-mentioned reaction step, the obtained (meth)acrylate having a vinyl ether group can be purified and isolated from the reaction solution.

[0112] The method for performing the purification step is not particularly limited, and examples thereof include methods based on raw material recovery operation, catalyst recovery operation, neutralization operation, filtration operation, decantation operation, extraction operation, water washing operation, evaporation operation, distillation operation, column chromatography operation, and the like.

[0113] The above-mentioned operations may be carried out alone or in combination of two or more thereof. Among these, purification by distillation operation is particularly preferred.

[0114] Furthermore, impurities removed by purification can be reused as raw materials or preparations as necessary.

[0115] <Step of separating raw material (meth)acrylate>

[0116] For example, the production method of the present invention preferably includes a step of separating unreacted raw material (meth)acrylic acid ester after the above-mentioned reaction step.

[0117] In the step of separating the raw material (meth)acrylic acid ester, it is preferred to separate the raw material (meth)acrylic acid ester by evaporating the raw material (meth)acrylic acid ester by distillation.

[0118] The separated raw material (meth)acrylate can be recovered and reused as a raw material (meth)acrylate in the reaction step or the like.

[0119] The temperature in the separation step of the raw material (meth)acrylate can be appropriately set according to the boiling point of the raw material (meth)acrylate, etc. The pressure is not particularly limited, and may be normal pressure, pressurized, or reduced pressure, preferably reduced pressure. In addition, the time can be appropriately set so that the raw material (meth)acrylate can be fully removed.

[0120] <Catalyst Separation Step>

[0121] For example, the production method of the present invention preferably includes a step of separating the catalyst after the above-mentioned reaction step.

[0122] In the above-mentioned catalyst separation step, the catalyst is preferably separated by evaporating the target product, the (meth)acrylate having a vinyl ether group, by distillation. Thus, impurities having a higher boiling point than the target product, the (meth)acrylate having a vinyl ether group, can be removed together with the catalyst.

[0123] The temperature in the catalyst separation step is usually higher than the temperature in the raw material (meth)acrylate separation step, and can be appropriately set according to the boiling point of the (meth)acrylate having a vinyl ether group as the target product. The pressure is not particularly limited, and may be normal pressure, pressurized, or reduced pressure, preferably reduced pressure. In addition, the time can be appropriately set.

[0124] <Step of Purifying the Target Product (Meth) Acrylic Acid Ester Having a Vinyl Ether Group>

[0125] The production method of the present invention preferably further comprises a step of purifying the target product (meth)acrylate having a vinyl ether group, for example, after the reaction step, the step of separating the raw material (meth)acrylate, and the step of separating the catalyst.

[0126] In the purification step of the (meth)acrylate having a vinyl ether group, it is preferred to separate the (meth)acrylate having a vinyl ether group as the target product by evaporating the (meth)acrylate having a vinyl ether group by distillation. In this way, impurities having a higher boiling point than the (meth)acrylate having a vinyl ether group as the target product can be removed. In addition, for example, it is more preferred to separate the (meth)acrylate having a vinyl ether group as the target product by evaporating the impurities having a lower boiling point than the (meth)acrylate having a vinyl ether group as the target product by distillation after removing them.

[0127] The purification step of the (meth)acrylate having a vinyl ether group is preferably performed using a distillation column. As a distillation column, for example, an Oldershaw type distillation column can be cited as a suitable distillation column.

[0128] The temperature in the purification process of the (meth)acrylate having a vinyl ether group can be appropriately set according to the boiling point of the (meth)acrylate having a vinyl ether group, the boiling point of impurities, etc. The pressure is not particularly limited, and normal pressure, pressurization, and reduced pressure are all possible, preferably reduced pressure. In addition, the time can be appropriately set.

[0129] Figure 1 This is a diagram showing an example of a production apparatus for carrying out the production method of the present invention.

[0130] Figure 1 The apparatus includes a reaction tank 11 for transesterification reaction, a first distillation column 21 for evaporating the raw material (meth)acrylate and separating it from the (meth)acrylate having a vinyl ether group, and a second distillation column 31 for evaporating the (meth)acrylate having a vinyl ether group and separating the catalyst and high-boiling impurities from the (meth)acrylate having a vinyl ether group.

[0131] The raw material solution 1 supplied to the apparatus is first introduced into the reaction tank 11. When the transesterification reaction is carried out in the reaction tank 11, by making the water content in the raw material solution 1 1500 ppm or more and 5 mass % or less, it is possible to obtain the (meth)acrylic acid ester having a vinyl ether group as the target product while fully preventing the polymerization of the (meth)acrylic acid group. It should be noted that, although not shown in the figure, when the alcohol produced as a by-product in the transesterification reaction is generally a low-boiling component, it can also be evaporated and removed from the reaction tank 11. The solution containing the (meth)acrylic acid ester having a vinyl ether group is sent to the first distillation tower 21 through the pipeline 71. In the first distillation tower 21, the unreacted raw material (meth)acrylic acid ester is evaporated and separated. The separated raw material (meth)acrylic acid ester is returned to the reaction tank 11 through the pipeline 81. The solution containing the (meth)acrylic acid ester having a vinyl ether group as the bottom liquid in the first distillation tower 21 is sent to the second distillation tower 31 through the pipeline 72. In the second distillation tower 31, the (meth)acrylic acid ester having a vinyl ether group is evaporated, and a crude product 3 is obtained from the top of the second distillation tower 31. The bottom liquid in the second distillation tower 31 contains a large amount of impurities having a higher boiling point than the (meth)acrylic acid ester having a vinyl ether group, such as a catalyst, and is therefore removed as a waste oil 2.

[0132] The (meth)acrylate having a vinyl ether group obtained by the production method of the present invention can be suitably used as a raw material for various industrial products.

[0133] Example

[0134] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. It should be noted that, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0135] [Comparative Example 1]

[0136] A 2L glass round-bottom flask (reactor) equipped with an Oldershaw-type distillation column, a stirring device, a thermometer, a gas introduction pipe, and a liquid sequential feeding line was prepared. 620 g of methyl acrylate (hereinafter abbreviated as "AM"), 453 g of diethylene glycol monovinyl ether (hereinafter abbreviated as "DEGV"), 1.1 g of phenothiazine (hereinafter abbreviated as "PTZ") as a primary antioxidant, 1.1 g of tris (2,4-di-tert-butylphenyl) phosphite (hereinafter abbreviated as "DBPP") as a secondary antioxidant, 0.32 g of N-nitrosophenylhydroxylamine ammonium salt (hereinafter abbreviated as "NPHN"), and 2.1 g of dibutyltin oxide (hereinafter abbreviated as "DBTO") as a catalyst were added to the round-bottom flask. It should be noted that the water content in AM was 110 ppm, and the water content in DEGV was 220 ppm.

[0137] Next, while liquid-phase bubbling of an oxygen / nitrogen mixed gas adjusted to 7 vol% was performed from the gas inlet pipe at 15 ml / min, the reactor was immersed in an oil bath at 120° C., and the temperature was started under total reflux.

[0138] As the reaction proceeds, methanol as a by-product gradually concentrates at the top of the Oldershaw type distillation column. After the temperature at the top of the column reaches the azeotropic point of AM and methanol, 63°C, distillation begins at a reflux ratio of 8 and a take-off rate of 50 g / h. At the same time, AM is supplied to the reactor through the liquid sequential feed line at a rate equal to the distillation rate. The start of distillation is regarded as the start of the reaction (reaction time is 0 hours), and the reaction is carried out for 8 hours.

[0139] At 8 hours after the start of the reaction, the reaction solution was sampled and the residual NPH content in the reaction solution was measured. The residual NPH content was quantified using high performance liquid chromatography, and the decomposition rate of NPH was calculated based on the obtained measured value. The results are shown in Table 1. It should be noted that in Comparative Example 1, the water content in the reaction solution was 156 ppm, and the molar ratio of water to NPH was 5.

[0140] [Comparative Example 2]

[0141] In the above Comparative Example 1, 0.25 g of ion exchange water was added to the raw material solution. The same operation as in Comparative Example 1 was performed to determine the decomposition rate of NPH. The results are shown in Table 1. In Comparative Example 2, the water content in the reaction solution was 390 ppm, and the molar ratio of water to NPH was 11.

[0142] [Comparative Example 3]

[0143] In the above Comparative Example 1, 0.72 g of ion exchange water was added to the raw material solution. The same operation as in Comparative Example 1 was performed to determine the decomposition rate of NPH. The results are shown in Table 1. In Comparative Example 3, the water content in the reaction solution was 820 ppm, and the molar ratio of water to NPH was 24.

[0144] [Comparative Example 4]

[0145] In the above Comparative Example 1, 1.13 g of ion exchange water was added to the raw material solution. The same operation as in Comparative Example 1 was performed to determine the decomposition rate of NPH. The results are shown in Table 1. In Comparative Example 4, the water content in the reaction solution was 1200 ppm, and the molar ratio of water to NPH was 35.

[0146] [Example 1]

[0147] In the above Comparative Example 1, 1.60 g of ion exchange water was added to the raw material solution. The same operation as in Comparative Example 1 was performed to determine the decomposition rate of NPH. The results are shown in Table 1. It should be noted that in Example 1, the water content in the reaction solution was 1640 ppm, and the molar ratio of water to NPH was 48.

[0148] [Table 1]

[0149]

[0150] (Summarize)

[0151] The results of Comparative Examples 1 to 4 and Example 1 are shown in Table 1. Figure 2 The correlation between the amount of water in the reaction solution and the decomposition rate of NPH is shown in FIG. 1 . It was confirmed that the more water there is in the reaction solution, the higher the decomposition rate of NPH tends to be.

[0152] [Comparative Example 5]

[0153] 1364 kg of AM, 997 kg of DEGV, 2.4 kg of PTZ as a primary antioxidant, 2.4 kg of DBPP as a secondary antioxidant, 0.70 kg of NPHN, and 4.6 kg of DBTO as a catalyst were added to a jacketed reactive distillation reactor. It should be noted that the water content in AM was 93 ppm, and the water content in DEGV was 215 ppm.

[0154] Next, a mixed gas of oxygen / nitrogen with an oxygen concentration adjusted to 7% by volume was added at 2 Nm 3 / h was bubbled into the liquid from the gas introduction pipe, and steam was supplied to the jacket under total reflux to start heating. The reaction temperature was set to 120°C.

[0155] As the reaction proceeds, methanol as a by-product gradually concentrates at the top of the distillation tower. After the temperature at the top of the tower reaches the azeotropic point of AM and methanol, 63°C, distillation begins at a reflux ratio of 8 and a flow rate of 110 kg / h. At the same time, AM is supplied to the reactor through the liquid sequential injection pipeline at the same flow rate. The start of distillation is regarded as the start of the reaction (reaction time is 0 hours), and the reaction is carried out in the form of 1 batch for 8 hours. In addition, in order to prevent polymerization inside the reactor, a 1% by mass PTZ / AM solution is supplied from the top of the distillation tower at a flow rate of 11 kg / h. It should be noted that in Comparative Example 5, the water content in the reaction solution is 144 ppm, and the molar ratio of water to NPH is 4.

[0156] When the above reaction was repeated, after the reaction of the 7th (7th batch) reaction was completed, when the reaction solution was transferred to the subsequent process, a decrease in the liquid feeding flow rate and an overcurrent in the liquid feeding pump were confirmed. Therefore, the reaction was stopped and the inside of the reactor was inspected. As a result, a large amount of polymer was attached to the gas phase of the reactor. The results are shown in Table 2.

[0157] [Comparative Example 6]

[0158] In Comparative Example 5, the same reaction as in Comparative Example 5 was repeated except that 1.69 kg of industrial pure water was additionally added to the raw material solution. The water content in the reaction solution of Comparative Example 6 was 857 ppm, and the molar ratio of water to NPH was 25.

[0159] As a result, after the reaction of the 12th reaction (12th batch) was completed, when the reaction solution was transferred to the subsequent process, a decrease in the liquid feeding flow rate and an overcurrent in the liquid feeding pump were confirmed. Therefore, the reaction was stopped and the inside of the reactor was inspected. As a result, a large amount of polymer was attached to the gas phase of the reactor. The results are shown in Table 2.

[0160] [Example 2]

[0161] In Comparative Example 5, the same reaction as in Comparative Example 5 was repeated except that 3.24 kg of industrial pure water was additionally added to the raw material solution. The water content in the reaction solution of Example 2 was 1511 ppm, and the molar ratio of water to NPH was 44.

[0162] As a result, until the 60th reaction (60th batch), when the reaction solution was transferred to the subsequent process, there was no decrease in the liquid delivery flow rate and no overcurrent in the liquid delivery pump, which was smooth. Afterwards, the interior of the reactor was inspected, and no polymer adhesion was confirmed in the gas phase part of the reactor. The results are shown in Table 2.

[0163] [Table 2]

[0164]

[0165] (Summarize)

[0166] As described above, it was confirmed that the NPH decomposition rate tended to increase as the amount of water in the reaction solution increased, and the result was shown to increase with increasing number of continuous production batches at the actual machine level.

Claims

1. A method for producing a (meth)acrylate having a vinyl ether group, characterized in that: Including the following processes: Using a raw material solution containing a raw material (meth)acrylate, a hydroxyl-containing vinyl ether compound, a catalyst, an N-nitrosoamine (salt) and water, a (meth)acrylate having a vinyl ether group is obtained by an ester exchange reaction, In the raw material solution, the mass ratio of water is 1500 ppm or more and 5 mass % or less, and The molar ratio of water to N-nitrosoamine (salt) is 40 or more and 1100 or less.

2. The method for producing a (meth)acrylate having a vinyl ether group according to claim 1, wherein: The hydroxyl-containing vinyl ether compound is diethylene glycol monovinyl ether, The (meth)acrylate having a vinyl ether group is 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.

3. The method for producing a (meth)acrylate having a vinyl ether group according to claim 1 or 2, characterized in that: The N-nitrosoamine (salt) is N-nitrosophenylhydroxylamine (salt).

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