Method for producing ethylenic isocyanate compound

Abstract

Provided is a method for producing a high-purity ethylenic isocyanate compound, in which (meth)acrylic anhydride is suppressed.　Provided is a method for producing a purified ethylenic isocyanate composition from a crude ethylenic isocyanate composition, wherein an alcohol is added to the crude ethylenic isocyanate composition, and the purified ethylenic isocyanate composition contains a (meth)acrylic acid ester compound which has an isocyanate group, and 0.2 mass% or less of an acid anhydride.　Also provided is an ethylenic isocyanate composition which contains an ethylenic isocyanate compound and 0.2 mass% or less of an acid anhydride.

Description

Method for producing ethylenically active isocyanate compounds

[0001] This invention relates to a method for producing ethylenically active isocyanate compounds useful for manufacturing various functional polymer materials. More specifically, this invention relates to a method for producing high-purity ethylenically active isocyanate compounds with reduced levels of (meth)acrylic anhydride generated during the manufacturing process.

[0002] Conventionally, common methods for producing ethylenically isocyanate compounds involved reacting (meth)acrylic acid with an ester salt of an amino alcohol and phosgene, or reacting isopropenyloxazoline with phosgene. However, these methods had problems such as the addition reaction of the (meth)acryloyl group to the double bond as a side reaction, and losses due to polymerization because the reaction was carried out while the double bond remained.

[0003] Therefore, a production method is known in which 3-chloro-2-methylpropionic acid = isocyanatoethyl or 3-chloropropionic acid 2 = isocyanatoethyl and a tertiary amine are converted to (meth)acryloyloxyalkyl isocyanate by a dehydrochlorination reaction in a solvent such as that shown in Patent Document 1.

[0004] Patent No. 4823546

[0005] However, the (meth)acrylic anhydride produced by the reaction of water introduced into the tertiary amine solvent used in the dehydrochlorination reaction with (meth)acrylic acid chloride present during the process has a small boiling point difference with the ethylenic isocyanate compound, making separation difficult by subsequent vacuum distillation.

[0006] Therefore, the object of the present invention is to provide a method for producing a high-purity ethylenic isocyanate compound with suppressed (meth)acrylic anhydride.

[0007] As a result of diligent research to solve the above problems, we found that these problems can be solved by adding a primary alcohol in the dehydrochlorination process. Specifically, we found that by adding a specific primary alcohol in the dehydrochlorination process and allowing the alcohol to react with (meth)acrylate chloride before the water reacts, the generation of methacrylic anhydride can be reduced, and residual impurities can be easily separated, thus completing the present invention.

[0008] [1] A method for producing a purified ethylenically isocyanate composition from a crude ethylenically isocyanate composition, wherein an alcohol having 4 or fewer carbon atoms or 10 or more carbon atoms is added to the crude ethylenically isocyanate composition, and the purified ethylenically isocyanate composition contains a (meth)acrylic acid ester compound having an isocyanate group and 0.2% by mass or less of an acid anhydride. [2] The method for producing the composition according to [1], wherein the crude ethylenically isocyanate composition contains 0.2% by mass or more of (meth)acrylic acid chloride.

[0009] [3] A method for producing the composition of [1] or [2], wherein the alcohol is a primary alcohol. [4] A method for producing the compositions of [1] to [3], wherein the alcohol has a boiling point of 120°C or less, or 230°C or more. [5] A method for producing the compositions of [1] to [4], wherein the acid anhydride is (meth)acrylic anhydride.

[0010] [6] A method for producing the composition according to [1] or [2], wherein the (meth)acrylic acid ester compound having an isocyanate group is represented by general formula (1). (R ３ -COO) ｎ -R ４ - (NCO) ｍ ...(1) (In formula (1), R ３ R is an ethylenically unsaturated group having 2 to 3 carbon atoms. ４is a hydrocarbon group with m + n valences and 1 to 7 carbon atoms. n and m are each 1 or 2.) [7] In a method for producing a purified ethylenic isocyanate composition, when producing the isocyanate composition, an ester derivative having an isocyanate group, represented by the following formula (2) in which the compound (1) is in the form of a hydrochloride (hereinafter also referred to as "compound (2)"), is subjected to dehydrochlorination treatment by adding an alcohol having 4 or fewer carbon atoms or 10 or more carbon atoms in the presence of a basic nitrogen compound [6]. (Cl-R ３’ -COO) ｎ -R ４ -(NCO) ｍ ... (2) (In formula (2), R ３’ is a saturated group of R ３ , R ４ and n, m are the same as in formula (1).)

[0011] [8] An ethylenic isocyanate composition containing an ethylenic isocyanate compound and 0.2% by mass or less of an acid anhydride. [9] The ethylenic isocyanate composition according to [8], wherein the ethylenic isocyanate compound is represented by the general formula (I). (R ３ -COO) ｎ -R ４ -(NCO) ｍ ... (1) (In formula (1), R ３ is an ethylenic unsaturated group having 2 to 3 carbon atoms. R ４ is a hydrocarbon group with m + n valences and 1 to 7 carbon atoms. n and m are each 1 or 2.)

[0012]

[10] The ethylenic isocyanate composition of [8] or [9], wherein the ethylenic isocyanate compound is at least one compound selected from 2-methacryloyloxyethyl isocyanate, 2-(isocyanatoethyloxy)ethyl methacrylate, 2-acryloyloxyethyl isocyanate, 2-(isocyanatoethyloxy)ethyl acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

[11] The ethylenic isocyanate composition of [8] to

[10] , characterized in that the acid anhydride is at least one compound selected from methacrylic anhydride and acrylic anhydride.

[12] The ethylenic isocyanate composition of [8] to

[11] , wherein the acid anhydride content is 1 ppm by mass or more.

[0013] In this invention, by adding a predetermined primary alcohol during the dechlorination treatment, the reaction between (meth)acrylic acid chloride and water occurs before the reaction can occur, thereby reducing the generation of methacrylic anhydride. Furthermore, any remaining impurities can be easily separated from the ethylenic isocyanate by separation operations such as distillation, for example, as short-chain or long-chain (meth)acrylic acid ester compounds. Therefore, according to this invention, high-purity ethylenic isocyanate can be produced efficiently.

[0014] Embodiments of the present invention will be described in detail below. In this invention, "(meth)acrylic acid" means methacrylic acid or acrylic acid.

[0015] <Crude Ethylene Isocyanate Composition> The crude ethylenic isocyanate composition includes impurities contained in the process of producing ethylenic isocyanate. The impurities are not particularly limited, but in the present invention, (meth)acrylate chloride is often included in the process. The crude ethylenic isocyanate composition preferably contains 0.2% by mass or more of (meth)acrylate chloride.

[0016] <Purified ethylenically unsaturated isocyanate composition>The purified ethylenically unsaturated isocyanate composition in one embodiment of the present invention contains a (meth)acrylic acid ester compound having an isocyanato group and 0.2% by mass or less of an acid anhydride. The composition substantially does not contain an acid anhydride and also includes a high-purity ethylenically unsaturated isocyanate.

[0017] - (Meth)acrylic acid ester compound having an isocyanato group The (meth)acrylic acid ester compound having an isocyanato group (—NCO) is a compound represented by the following formula (1).

[0018] (R ３ —COO) ｎ —R ４ —(NCO) ｍ ...(1)

[0019] In formula (1), R ３ is an ethylenically unsaturated group having 2 or 3 carbon atoms. When the carbon number of R ３ is 4 or more, the reactivity of the ethylenically unsaturated group may decrease. R ３ is preferably CH ２ =CH(CH ３ )— or CH ２ =CH ２ — (vinyl group) from the viewpoint of easy availability of raw materials. The number of ethylenically unsaturated bonds contained in R ３ may be 1 or 2.

[0020] In formula (1), R ４ is an m + n-valent hydrocarbon group having 1 to 7 carbon atoms, preferably 2 to 6 carbon atoms, more preferably 3 to 5 carbon atoms, and still more preferably 2 carbon atoms, and may be linear or branched. Also, R ４ may contain an ether bond. R ４ is preferably —CH ２ —, —CH ２ CH ２ —, or —CH ２ CH ２ OCH ２ CH ２ — from the viewpoint of easy availability of raw materials, and more preferably —CH ２ CH ２ —.

[0021] In formula (1), m and n are each an independent integer of 1 or 2, and from the viewpoint of ease of manufacture, it is preferable that both be 1.

[0022] Examples of the (meth)acrylic acid ester compound having an isocyanato group represented by the formula (1) include 2-methacryloyloxyethyl isocyanate, 3-methacryloyloxy-n-propyl isocyanate, 2-methacryloyloxyisopropyl isocyanate, 4-methacryloyloxy-n-butyl isocyanate, 2-methacryloyloxy-tert-butyl isocyanate, 2-methacryloyloxybutyl-4-isocyanate, 2-methacryloyloxybutyl-3-isocyanate, 2-methacryloyloxybutyl-2-isocyanate, 2-methacryloyloxybutyl-1-isocyanate, 5-methacryloyloxy-n-pentyl isocyanate, 6-methacryloyloxy-n-hexyl isocyanate, 7-methacryloyloxy-n-heptyl isocyanate, 2-(isocyanatoethyloxy)ethyl methacrylate, 3-methacryloyloxyphenyl isocyanate, 4-methacryloyloxyphenyl isocyanate, 2-acryloyloxyethyl isocyanate, 3-acryloyloxy-n-propyl isocyanate, 2-acryloyloxyisopropyl isocyanate, 4-acryloyloxy-n-butyl isocyanate, 2-acryloyloxy-tert-butyl isocyanate, 2-acryloyloxybutyl-4-isocyanate, 2-acryloyloxybutyl-3-isocyanate, 2-acryloyloxybutyl-2-isocyanate, 2-acryloyloxybutyl-1-isocyanate, 5-acryloyloxy-n-pentyl isocyanate, 6-acryloyloxy-n-hexyl isocyanate, 7-acryloyloxy-n-heptyl isocyanate, 2-(isocyanatoethyloxy)ethyl acrylate, 3-acryloyloxyphenyl isocyanate, 4-acryloyloxyphenyl isocyanate, 1,1-bis(methacryloyloxymethyl)methyl isocyanate, 1,1-bis(methacryloyloxymethyl)ethyl isocyanate, 1,1-bis(acryloyloxymethyl)methyl isocyanate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

[0023] Of these, from the viewpoint of ease of manufacture and / or availability of raw materials, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-(isocyanatoethyloxy)ethyl acrylate, 2-(isocyanatoethyloxy)ethyl methacrylate, or 1,1-bis(acryloyloxymethyl)ethyl isocyanate is preferred, more preferably 2-acryloyloxyethyl isocyanate or 2-methacryloyloxyethyl isocyanate, and even more preferably 2-acryloyloxyethyl isocyanate.

[0024] The acid anhydrides included in the ethylenically isocyanate composition are not particularly limited, but include methacrylic anhydride, acrylic anhydride, maleic anhydride, and itaconic anhydride, and examples include methacrylic anhydride and acrylic anhydride. The acid anhydride content is 0.2% by mass or less, more preferably 0.15% by mass or less, and even more preferably 0.10% by mass or less, based on the ethylenically isocyanate composition. The acid anhydride content is preferably 1 ppm by mass or more, more preferably 10 ppm by mass or more, and even more preferably 100 ppm by mass or more, based on the ethylenically isocyanate composition.

[0025] <Method for Producing a Purified Ethylene Isocyanate Composition> The production method of this embodiment includes a method for producing a purified ethylenic isocyanate composition from a crude ethylenic isocyanate composition, in which an alcohol having 4 or fewer carbon atoms or 10 or more carbon atoms is added to the crude ethylenic isocyanate composition to produce a purified ethylenic isocyanate composition containing an isocyanate group-containing (meth)acrylic acid ester compound and 0.2% by mass or less of an acid anhydride. Specifically, in the present invention, when producing an isocyanate composition, an ester derivative having an isocyanate group (hereinafter also referred to as "compound (2)") represented by formula (2) with compound (1) as the hydrochloride salt is subjected to dehydrochlorination treatment by adding an alcohol having 4 or fewer carbon atoms or 10 or more carbon atoms in the presence of a basic nitrogen compound.

[0026] (Cl-R ３’ -COO)ｎ -R ４ - (NCO) ｍ ...(2) (In formula (2), R ４ n and m are the same as in formula (1). The (meth)acrylic acid ester compounds having an isocyanate group obtained by the production method according to the present invention are as described above.

[0027] In formula (2), R ３’ R in equation (1) ３ The saturated group has two valences, R ４ R is in equation (1) ４ This corresponds to the same as in formula (1). n and m are the same as in formula (1). As such compound (2), at least one of the compounds represented by the following formulas (2-1) and (2-2) is preferred.

[0028]

[0029] The method for producing the above compound (2) is not particularly limited and can be obtained by conventionally known methods. For example, as described in Japanese Patent Application Publication No. 2007-55993, it can be produced by isocyanating an ester compound obtained by esterifying a hydroxyamine mineral salt and (meth)acrylic acid chloride, and then treating the isocyanate compound with hydrochloric acid.

[0030] The dehydrochlorination treatment is carried out in the presence of a basic compound by adding the aforementioned alcohol. Generally, compounds with basic nitrogen are used as such basic compounds. However, if a hydrogen atom remains on the nitrogen, it may react with the isocyanate group of the raw material and the target product, which may reduce the yield or cause the basicity of the nitrogen atom to disappear.

[0031] Therefore, in the manufacturing method of the present invention, a basic nitrogen compound having tertiary nitrogen is used.

[0032] Examples of the basic nitrogen compound include various trialkylamines, compounds in which two or three alkyl groups bonded to a nitrogen atom are bonded to each other to form a cyclic structure (the ring may contain oxygen, sulfur, or other nitrogen atoms), and amines in which one of the groups bonded to the nitrogen atom is an aromatic ring group (e.g., N,N-dialkylaniline, N,N-dialkylaminopyridine, etc.).

[0033] Specifically, trimethylamine, triethylamine, tripropylamine, dimethylethylamine, dimethylisopropylamine, diethylmethylamine, dimethylbutylamine, dimethylhexylamine, diisopropylethylamine, dimethylcyclohexylamine, tetramethyldiaminomethane, dimethylbenzylamine, tetramethylethylenediamine, tetramethyl-1,4-diaminobutane, tetramethyl-1,3-diaminobutane, tetramethyl-1,6-diaminobutane Examples include minohexane, pentamethyldiethylenetriamine, 1-methylpiperidine, 1-ethylpiperidine, N,N-dimethylpiperazine, N-methylmorpholine, 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1,5-diazabicyclo[4.3.0]-5-noene (DBN), 2,4-diazabicyclo[2.2.2]octane (DABCO), N,N-dimethylaniline, N,N-diethylaniline, and ion exchange resins containing tertiary nitrogen.

[0034] Among these, trimethylamine, triethylamine, tripropylamine, and tetramethylethylenediamine are preferred. Furthermore, the above basic nitrogen compounds may be used individually or in combination of two or more.

[0035] The dehydrochlorination treatment in this invention may be carried out using the reaction solution obtained when compound (2) is synthesized as described above, or the compound (2) synthesized as described above may be purified beforehand by a method such as distillation before the treatment is carried out. The dehydrochlorination treatment can be carried out by using 1 molar equivalent of the basic nitrogen compound for every 1 mole of compound (2). An excess of the basic nitrogen compound may be used, but depending on the conditions, the remaining basic nitrogen compound may promote the polymerization reaction. On the other hand, if the amount of basic nitrogen compound used is insufficient, compound (1) may remain, and the reaction may not be completed.

[0036] Typically, a basic nitrogen compound can be used in an amount of 0.5 to 10 molar equivalents, preferably 0.8 to 5.0 molar equivalents, and more preferably 0.9 to 2.0 molar equivalents, per mole of compound (2).

[0037] Primary alcohols are preferred as the alcohol. The number of carbon atoms in the alkyl group of the alcohol is 4 or less or 10 or more. Alkyl groups with this number of carbon atoms are easily removed by distillation, even if they remain as short-chain or long-chain (meth)acrylic acid ester compounds. The boiling point of the alcohol is preferably 120°C or less or 230°C or higher at 1 atmosphere. Alkyl groups within this range are easily removed by distillation.

[0038] Typically, the amount of alcohol added can be in the range of 0.5 to 10 molar equivalents, preferably 0.8 to 5.0 molar equivalents, and more preferably 0.9 to 2.0 molar equivalents, of the basic nitrogen compound. By adding alcohol, the (meth)acrylic acid chloride produced during the dechlorination treatment reacts with the alcohol before it reacts with water, thereby reducing the generation of methacrylic anhydride. In addition, residual impurities containing alcohol can be easily separated.

[0039] The temperature for the dechlorination treatment should preferably be 40 to 120°C, more preferably 40 to 100°C, because high temperatures may cause polymerization of the target compound (1).

[0040] The reaction time varies depending on the reaction temperature, the strength of the basic nitrogen compound, etc., but is usually 10 minutes to 40 hours, preferably 30 minutes to 30 hours.

[0041] For the reaction, solvents that do not react with the isocyanate group, such as hydrocarbons like toluene and xylene; acetic acid esters like ethyl acetate, propyl acetate, and butyl acetate; and aprotic solvents like chlorine-based solvents such as methylene chloride can be used. It is preferable that the solvent has a lower boiling point than the product.

[0042] After dehydrochlorination, the resulting hydrochloride salt may be removed. Filtration is a common method of removal. Alternatively, if dehydrochlorination is performed in a solvent with low solubility in water, the resulting hydrochloride salt may be extracted with water. In this case, it is preferable to neutralize any excess basic nitrogen compound before extraction to reduce the decomposition of the target substance.

[0043] After dehydrochlorination, the hydrochloride salt is removed as needed, and the remaining basic nitrogen compounds and alcohols are separated. Then, the above compound (1) is isolated and purified by methods such as distillation, crystallization, extraction, and column treatment, preferably by distillation.

[0044] The distillation temperature is not limited, but is preferably between 90°C and 140°C. At this distillation temperature, sufficient separation is possible, and purification can be performed efficiently. The pressure during distillation is also not particularly limited, and is acceptable as long as it is between 1.0 and 10.0 kPa, but vacuum distillation such as thin-film distillation is preferred.

[0045] When performing distillation, a polymerization inhibitor may be added to the composition before heating begins. Adding a polymerization inhibitor prevents the mixture from polymerizing and gelling due to the temperature rise associated with distillation. The polymerization inhibitor added to the composition prevents gelling during storage and transport, contributing to improved stability during storage. The polymerization inhibitor may also be added to the composition obtained after distillation, if necessary.

[0046] Specific examples of polymerization inhibitors include hydroquinone, methoxyhydroquinone, catechol, p-tert-butylcatechol, cresol, 2,6-di-tert-butyl-4-methylphenol (BHT), phenothiazine, and 2,6-di-t-butyl-p-cresol.

[0047] As described above, a purified ethylenically isocyanate composition in which the amount of acid anhydride is reduced to 0.2% by mass or less can be produced. The present invention also includes a purification method as part of the method of production. Another embodiment of the present invention relates to an ethylenically isocyanate composition comprising an ethylenically isocyanate compound and 0.2% by mass or less of acid anhydride. The ethylenically isocyanate compound, acid anhydride, and their content are as described above.

[0048] The present invention will be described below with reference to examples, but the present invention is not limited in any way to these examples.

[0049] [Example 1] (Dehydrochlorination reaction) In a flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube, 65.27 g of toluene, 11.71 g of methacryloyloxyethyl isocyanate as a solvent, and 0.26 g of methacrylate chloride as a carboxylic acid chloride were added, and the mixture was stirred while purging with nitrogen gas, and the temperature was raised to 80°C. Next, 17.88 g of pyridine as a tertiary amine and 0.488 g of phenothiazine as a polymerization inhibitor were added, and methanol was added in the amounts shown in Table 1 to prepare a mixed solution. The prepared mixed solution was placed in a flask at atmospheric pressure under a nitrogen gas atmosphere, and the dehydrochlorination reaction was carried out at 80°C for 20 hours to obtain a dehydrochlorination slurry.

[0050] The generated hydrochloride salt was removed by filtration to obtain a crude methacryloyloxyethyl isocyanate composition solution. Toluene was removed from the obtained crude methacryloyloxyethyl isocyanate composition solution using an evaporator, and a fraction of methacryloyloxyethyl isocyanate was obtained by thin-film distillation. The obtained fraction was distilled to obtain purified (meth)acryloyloxyalkyl isocyanate. The concentration of methacrylic anhydride in the purified methacryloyloxyethyl isocyanate was confirmed to be 0.2% by mass or less by gas chromatography. The results are shown in Table 1.

[0051] [Examples 2-8 and Comparative Examples 1-5] (Meth)acryloyloxyalkyl isocyanates were obtained in the same manner as in Example 1, except that the type and amount of the 3-chloropropionic acid ester derivative having an isocyanate group, the tertiary amine, and the alcohol were changed as shown in Table 1. In Comparative Examples 1 and 5, no alcohol was added.

[0052] [Example 10] (Acid Chloride Reaction) In a flask equipped with a stirrer, condenser, thermometer, and gas inlet tube, 110.5 g of methacrylic acid was charged as a carboxylic acid, 1.34 g of phenothiazine as a polymerization inhibitor, and 0.24 g of dimethylformamide as a catalyst. Under heating conditions of 60°C, 139.2 g of carbonyl chloride (gas) was reacted with the substrate for 5 hours to obtain 134.0 g of crude methacrylic acid chloride [a].

[0053] (Esterification reaction) In a flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube, 114.0 g of ethanolamine hydrochloride and 80 g of toluene as a solvent were charged. Under heating conditions of 90°C, 130.0 g of methacrylate chloride [a] was added to the substrate, and after 1 hour, 267.5 g of crude aminoethyl methacrylate hydrochloride toluene solution [b] was obtained.

[0054] (Isocyanation Reaction) 267.0 g of a toluene solution of crude aminoethyl methacrylate hydrochloride [b] was charged into a flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer, and a gas inlet tube. 170 g of carbonyl chloride (gas) was reacted at 90 °C for 9 hours to obtain 340.6 g of a toluene solution of crude methacryloyloxyethyl isocyanate [c] containing 0.85 g of carboxylic acid chloride (methacrylic acid chloride).

[0055] (Hydrochloric Acid Removal Reaction) 340.0 g of a toluene solution of crude methacryloyloxyethyl isocyanate [c] containing 0.85 g of carboxylic acid chloride was charged into a flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer, and a gas inlet tube. The mixture was stirred while purging with nitrogen gas and heated to 80 °C. Next, 90.5 g of triethylamine as a tertiary amine, 0.52 g of phenothiazine as a polymerization inhibitor, and 1.28 g of n-decanol were mixed to prepare a mixed solution. The prepared mixed solution was added into a flask under normal pressure in a nitrogen gas atmosphere, and a hydrochloric acid removal reaction was carried out at 80 °C for 20 hours to obtain a hydrochloric acid removal slurry. Purification was carried out in the same manner as in Example 1. It was confirmed that the concentration of methacrylic anhydride in the purified methacryloyloxyethyl isocyanate was 0.2% by mass or less.

[0056] [Measurement Conditions for Gas Chromatography] Column: Inner diameter 0.32 mm, length 30 m, liquid phase film thickness 1.0 μm (Product name: DB-1, manufactured by J&W Scientific) Column temperature: Initial temperature 50 °C, then heated at 10 °C / min, final temperature 300 °C (for 15 minutes) Inlet temperature: 300 °C Detector temperature: 300 °C Detector: Hydrogen flame ionization (FID) detector Carrier gas: Helium Flow rate (column): 1.2 mL / min

[0057]

[0058] The abbreviations in the table are as follows: MAC... Methacrylic acid chloride AC... Acrylic acid chloride MOI... Methacryloyloxyalkyl isocyanate AOI... Acryloyloxyalkyl isocyanate Anhydrous MAA... Methacrylic anhydride Anhydrous AA... Acrylic anhydride In addition, "area%" indicates the area percentage.

[0059] In the examples, the amount of acrylic anhydride was reduced to 0.2% by mass or less.

Claims

1. A method for producing a purified ethylenically isocyanate composition from a crude ethylenically isocyanate composition, wherein an alcohol having 4 or fewer carbon atoms or 10 or more carbon atoms is added to the crude ethylenically isocyanate composition, and the purified ethylenically isocyanate composition contains a (meth)acrylic acid ester compound having an isocyanate group and 0.2% by mass or less of an acid anhydride.

2. The method for producing the composition according to claim 1, wherein the crude ethylenic isocyanate composition contains 0.2% by mass or more of (meth)acrylate chloride.

3. A method for producing the composition according to claim 1 or claim 2, wherein the alcohol is a primary alcohol.

4. A method for producing the composition according to claim 1 or claim 2, wherein the alcohol has a boiling point of 120°C or lower, or 230°C or higher.

5. A method for producing the composition according to claim 1 or claim 2, wherein the acid anhydride is (meth)acrylic acid anhydride.

6. A method for producing the composition according to claim 1 or claim 2, wherein the (meth)acrylic acid ester compound having an isocyanate group is represented by general formula (1). (R ３ -COO) ｎ -R ４ - (NCO) ｍ ...(1) (In formula (1), R ３ R is an ethylenically unsaturated group having 2 to 3 carbon atoms. ４ (This refers to an m+n valent hydrocarbon group with 1 to 7 carbon atoms. n and m are each 1 or 2.) 7. In the method for producing a purified ethylenic isocyanate composition, when producing the isocyanate composition, an ester derivative having an isocyanate group represented by the following formula (2) in which the compound (1) is in the form of a hydrochloride (hereinafter also referred to as "compound (2)") is subjected to dehydrochlorination treatment by adding an alcohol having 4 or less carbon atoms or 10 or more carbon atoms in the presence of a basic nitrogen compound. The method for producing the composition according to claim 6. (Cl-R ３’ -COO) ｎ -R ４ -(NCO) ｍ ...(2) (In formula (2), R ３’ is a saturated group of R ３ , and R ４ and n, m are the same as in formula (1).) 8. An ethylenically isocyanate composition comprising an ethylenically isocyanate compound and 0.2% by mass or less of an acid anhydride.

9. The ethylenic isocyanate composition according to claim 8, wherein the ethylenic isocyanate compound is represented by general formula (1). (R ３ -COO) ｎ -R ４ - (NCO) ｍ ...(1) (In formula (1), R ３ R is an ethylenically unsaturated group having 2 to 3 carbon atoms. ４ (This refers to an m+n valent hydrocarbon group with 1 to 7 carbon atoms. n and m are each 1 or 2.) 10. The ethylenic isocyanate composition according to claim 8 or 9, wherein the ethylenic isocyanate compound is at least one compound selected from 2-methacryloyloxyethyl isocyanate, 2-(isocyanatoethyloxy)ethyl methacrylate, 2-acryloyloxyethyl isocyanate, 2-(isocyanatoethyloxy)ethyl acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

11. The ethylenic isocyanate composition according to claim 8 or 9, characterized in that the acid anhydride is at least one compound selected from methacrylic anhydride and acrylic anhydride.

12. The ethylenic isocyanate composition according to claim 8, wherein the content of the acid anhydride is 1 ppm by mass or more.

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