JPH09323968A - Purification of isocyanate compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly reduce the concentration of hydrolyzable chlorine as an impurity in an isocyanate compound being in wide use as a raw material for coating materials, adhesives, molded products, etc. SOLUTION: A crude isocyanate compound containing hydrolyzable chlorine is treated with an epoxy compound in the presence of amine(s) to obtain the objective isocyanate compound reduced in the hydrolyzable chlorine content. In this case, the amine(s) is pref. at least one kind selected from among 4-15C trialkylamines, compounds of the formula, [H2 N-(CH2 CH2 NH)n -H ((n) is an integer of >=2)] and 2-(1-3)C alkyl-4-(1-3)C alkylimidazoles, and it is preferable that the amount(s) of the amine(s) to be used is 0.2-2 equivalent times that of the hydrolyzable chlorine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying an isocyanate compound, more specifically, a hydrolyzable compound which is an impurity in an isocyanate compound widely used as a raw material for paints, adhesives, moldings and the like. It relates to a method of reducing the chlorine concentration.

[0002]

BACKGROUND OF THE INVENTION Isocyanato groups are primary or secondary.
A compound having a high reactivity with a compound having active hydrogen, such as a compound having a substituent such as a primary amino group or a hydroxyl group, and having this isocyanato group (isocyanate compound)
Is used in many applications such as paints, adhesives and molding materials, and is a very important raw material compound in industry.

Except for special cases, this isocyanate compound is usually produced by reacting a compound having a primary amino group or a salt thereof (eg hydrochloride, carbonate) with phosgene.

Among the above isocyanate compounds, 2-
Isocyanatoethyl methacrylate can also be produced by the reaction of 2-isopropenyl oxazoline and phosgene (Japanese Patent Laid-Open No. 54-5921), and methacryloyl isocyanate can be produced by the reaction of methacrylic acid amide with oxalyl dichloride. Can [Prog
ress in Organic Coatings, 20 (1992), p.471].

Thus, the isocyanate compound produced by the reaction using a chlorine compound such as phosgene and oxalyl dichloride usually contains a chlorine compound as an impurity.

An isocyanate compound (also called a crude isocyanate compound or an impurity-containing isocyanate compound) which is a by-product during the production of such an isocyanate compound and contains impurities generally called "hydrolyzable chlorine" is
In particular, when it is used in a urethanization reaction, it becomes a catalyst poison, and when a derivative obtained from such a crude isocyanate compound is used in a polymerization reaction, the obtained product may be colored, and such a polymer is When it is used as an electronic material, various unfavorable effects such as corrosion of the obtained electronic parts may occur.

Therefore, various methods for reducing the content of hydrolyzable chlorine in the above-mentioned isocyanate compound have been conventionally proposed. For example, JP-A-53-119823 discloses a hydrolyzable chlorine-containing isocyanate compound,
A method of mixing fine alkali metal carbonate at a high temperature for a long time is disclosed. JP-A-59-172450 discloses a hydrolyzable chlorine-containing isocyanate compound, a zinc carboxylate and a hindered phenol. A method of adding a system antioxidant and heating and then distilling is disclosed. US Pat. No. 3,465,023 discloses a method of synthesizing an isocyanate in a water-insoluble solvent and then washing with an aqueous sodium hydrogen carbonate solution. And German Patent 224937.
No. 5 discloses a method of treating polymethylene polyphenyl isocyanate containing hydrolyzable chlorine with an epoxy compound.

As a method which does not use the above-mentioned alkali metal carbonate or the like, Japanese Patent Laid-Open No. 61-161250 discloses a method in which a hydrolyzable chlorine-containing isocyanate compound is vaporized and then condensed at a temperature of 70 ° C. or higher. A method for purifying an isocyanate compound by performing the reaction is shown.

However, in the methods proposed so far, the content of hydrolyzable chlorine cannot be sufficiently reduced, or there are various problems to be solved for industrial implementation. As described in JP-A-53-119823, in the method of mixing the hydrolyzable chlorine-containing isocyanate compound and the alkali metal carbonate at high temperature, it is difficult to separate the treated isocyanate compound and the carbonate. Therefore, loss is unavoidable, and US Patent 3
As shown in Japanese Patent No. 465023, in the method of washing with an aqueous solution of sodium hydrogencarbonate, a white insoluble matter is deposited at the boundary between the solvent phase and the aqueous phase, which makes the subsequent separation operation troublesome and causes the equipment to be contaminated. There is a problem that it becomes. Further, in these methods, there is a risk of contamination of the isocyanate compound by sodium ion, and even if the sodium ion content is a trace level of ppm order (one millionth), the isocyanate compound Is a serious problem when used as an electronic material.

Particularly when purifying an isocyanate compound having a carbon-carbon double bond, it is required to effectively reduce the content of hydrolyzable chlorine while preventing the polymerization reaction between the isocyanate compounds. However, for such a carbon-carbon double bond-containing isocyanate compound,
Until now, there has been no satisfactory purification method.

In US Pat. No. 4,310,688, 0.21
% Of hydrolyzable chlorine by treating a solution of isocyanatoethyl methacrylate in methylene chloride with a vicinal epoxy group-containing compound (eg, 1,2-butylene oxide) to give a hydrolyzable chlorine content of 0.05%. It has been shown that it can be reduced to. However, this method can only reduce the content of hydrolyzable chlorine to several hundred ppm at most, and the purified isocyanate compound obtained by such a method is not suitable for use in applications such as electronic materials as described above. It was not enough.

[0012]

It is an object of the present invention to solve the problems associated with the prior art as described above, and it is contained as an impurity in a crude isocyanate compound or is bound to the isocyanate compound. PROBLEM TO BE SOLVED: To provide a method for purifying an isocyanate compound which is capable of efficiently reducing / removing hydrolyzable chlorine contained therein to obtain a high-purity isocyanate compound in a high yield, and which can be easily carried out industrially. Is intended.

The present invention is also suitable for the purification of an aliphatic isocyanate compound which has been conventionally difficult to remove hydrolyzable chlorine, and particularly, an aliphatic isocyanate having a polymerizable double bond. It is an object of the present invention to provide a method for purifying an isocyanate compound, which is suitable for purifying the compound.

[0014]

SUMMARY OF THE INVENTION In the method for purifying an isocyanate compound according to the present invention, a crude isocyanate compound containing (or bound to) hydrolyzable chlorine is treated with an epoxy compound in the presence of amines. According to the above, an isocyanate compound having a reduced hydrolyzable chlorine content is obtained.

In a preferred embodiment of the present invention, the above isocyanate compound preferably has an isocyanate group bonded to an aliphatic carbon, and preferably has a carbon-carbon double bond.

In a preferred embodiment of the present invention, the amines are trialkylamines (wherein the alkyl group has 4 to 15 carbon atoms), compounds represented by the following formula [A] and 2-alkyl. -4-alkyl imidazole (however, the carbon number of the alkyl group is 1 to 3 independently.
It is. It is desirable that it is at least one compound selected from the above.

H ₂ N- (CH ₂ CH ₂ NH) _n -H ... [A] (In the formula [A], n represents an integer of 2 or more.) Further, in the present invention, the above amines Is preferably used in an amount of 0.2 to 2 times the equivalent of hydrolyzable chlorine, and the epoxy compound is preferably used in the amount of 1 to 5 times the equivalent of hydrolyzable chlorine.

In such a method for purifying an isocyanate compound according to the present invention, a crude isocyanate compound containing or bound with hydrolyzable chlorine is treated with an epoxy compound in the presence (in the coexistence) of amines as a catalyst. Since the compound is treated with a compound, an isocyanate compound having a significantly reduced content of hydrolyzable chlorine can be efficiently obtained in good yield without adversely affecting the quality of the isocyanate compound. Moreover, such a purification method can be easily implemented industrially.

[0019]

DETAILED DESCRIPTION OF THE INVENTION The method for purifying an isocyanate compound according to the present invention will be specifically described below.

In the method for purifying an isocyanate compound according to the present invention, hydrolyzable chlorine is contained or bound (also referred to as "hydrolyzable chlorine is contained" or "bonded" in the present invention). ) The crude isocyanate compound is treated with an epoxy compound in the presence of amines to obtain an isocyanate compound having a reduced content of hydrolyzable chlorine. [Crude Isocyanate Compound] The crude isocyanate compound used for purification in the present invention contains or bonds hydrolyzable chlorine to be separated and removed. The isocyanate compound in such a crude isocyanate compound is not particularly limited as long as it has an isocyanate group (-N = C = O) in the molecule, and further, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an ester It may have a bond, a sulfonyl group, or the like.

Examples of such a crude isocyanate compound include, for example, as described above: methacrylic acid-2-aminoethyl ester hydrochloride or 2-isopropenyloxazoline obtained by reaction with phosgene and hydrolyzable. Chlorine-bonded 2-isocyanatoethyl methacrylate: Methacryloyl isocyanate, etc., obtained by the reaction of methacrylic acid amide and oxalyl dichloride, and having hydrolyzable chlorine bonded thereto, such as: aromatic amine (eg, aniline) or its Phenylisocyanate bound to hydrolyzable chlorine obtained by acting phosgene on hydrochloride: bound to hydrolyzable chlorine obtained by acting phosgene on hydrochloride of aliphatic amine (eg, isophoronediamine) Aliphatic diisocyanates, etc. It is.

In such a crude isocyanate compound, the hydrolyzable chlorine is, for example, JIS K 1556.
It is defined as chlorine determined when potentiometric titration is performed using a silver nitrate solution after treating a crude isocyanate compound with methanol as described in 5.7 of "Tolylene diisocyanate test method". , Not a single compound, for example, an isocyanate compound R
When represented as -NCO, it may be present in the following form, but the details are unknown.

[0023]

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The method for purifying an isocyanate compound according to the present invention is particularly suitable for purifying an isocyanate compound having a carbon-carbon double bond (unsaturated bond) as described above, and as an isocyanate compound, Is preferably an isocyanato group to which an aliphatic hydrocarbon group is bonded (eg, 2-isocyanatoethyl methacrylate). The content of hydrolyzable chlorine in such a crude isocyanate compound is not particularly limited, but it is preferable that the content of the hydrolyzable chlorine is as small as possible, for example, the hydrolyzable chlorine content in the crude isocyanate compound to be treated. Chlorine is 20 to 20,000 (20,000) ppm, preferably 100
What is contained in an amount of about 5,000 ppm is used. [Epoxy compound] As the epoxy compound, those having a larger boiling point difference between the epoxy compound and the isocyanate compound obtained by purification are advantageous in the separation and purification described later, and the boiling point difference is usually 5 It is desirable that the temperature is not lower than 0 ° C, preferably not lower than 20 ° C.

The epoxy compound is not particularly limited as long as it has an epoxy group in the molecule, and examples thereof include aliphatic or alicyclic alkylene oxide, epoxidized fatty acid ester, and epoxidized glyceride. The epoxy compound may be liquid or solid at room temperature (20 ° C.).

As the aliphatic alkylene oxide, the following formula [B]:

[0027]

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[In the formula [B], R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having about 1 to 10 carbon atoms,
n represents an integer of about 0 to 2. ] Specifically, ethylene oxide (R ¹ = R ² = H, n = 0), trimethylene oxide (R ¹ = R ² = H, n = 1), butylene oxide (R ¹ = R) ² = CH ₃ , n = 0) and the like.

The alicyclic alkylene oxide has the following formula [C]:

[0030]

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[In the formula [C], R ³ and R ⁴ represent a hydrogen atom or an alkyl group having about 1 to 10 carbon atoms, and may be the same or different, and p is about 1 to 6; Indicates an integer. ], And specific examples thereof include cyclohexene oxide (R ³ = R ⁴ = H, p = 4), cyclopentene oxide (R ³ = R ⁴ = H, p = 3), and the like.

The epoxidized fatty acid ester has the following formula [D]:

[0033]

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[In the formula [D], R ⁶ represents a hydrogen atom or a saturated or unsaturated chain hydrocarbon group having about 1 to 15 carbon atoms, which may have a branch, and R ⁷ represents , Optionally having an ether bond (-O-), having 1 to 15 carbon atoms
Shows a saturated or unsaturated chain hydrocarbon group of about R,
⁸ represents a saturated or unsaturated chain hydrocarbon group having about 1 to 10 carbon atoms, and n represents an integer of about 0 to 6. ], Specifically, for example, epoxidized alkyl stearate (R ⁶ = CH ₃ (CH ₂ ) ₇ , R ⁷ = (CH ₂ ) ₇ ,
R ⁸ = alkyl group, n = 0), etc., molecular weight 400-500
Includes some degree of epoxidized fatty acid ester.

The epoxidized triglyceride is represented by the following formula [E]:

[0036]

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[In the formula [E], R ¹⁰ , R ¹² and R ¹⁴ each independently have an ether bond and have 1 carbon atom.
Is a (branched) chain hydrocarbon bond which may have an unsaturated bond of about 15 to about 15, and R ¹¹ , R ¹³ and R ¹⁵ are each independently a saturated or unsaturated one having about 1 to 10 carbon atoms. A (branched) chain hydrocarbon group is shown. Each s independently represents 0 or 1, and at least one of the three s represents 1. ] Specifically, for example, an epoxidized triglyceride obtained by dropping an oil and fat such as soybean oil and cottonseed oil in a solvent such as acetic acid and formic acid in the presence of an acid catalyst with hydrogen peroxide solution [molecular weight : About 500 to 1500, iodine value: 2
14, oxirane oxygen content: about 2 to 15%].

The amount of oxirane oxygen in the epoxy compound is determined by reacting the epoxy compound with a known amount of hydrogen chloride, titrating the excess with an alkaline standard solution, and comparing the titer with a blank value. It

In the present invention, 1 of these epoxy compounds is used.
They can be used alone or in combination of two or more. Among the above epoxy compounds, epoxidized fatty acid ester [D] and epoxidized triglyceride [E] are preferably used.

The epoxy compound is preferably used in an amount of 1 to 5 equivalents, preferably 1.5 to 3 equivalents per equivalent of hydrolyzable chlorine (1 mol of chlorine atom). When the amount of the epoxy compound used is less than 1 equivalent per 1 equivalent of hydrolyzable chlorine, the hydrolyzable chlorine in the crude isocyanate compound cannot be efficiently and sufficiently removed, the effect is small, and the amount is more than 5 equivalents. However, the effect of addition is not improved any more, which is uneconomical.

The equivalent number of the epoxy compound is calculated as the equivalent number of moles of oxygen atoms (oxirane oxygen) constituting the epoxy group contained in the epoxy compound.

[Amines] As amines, primary, 2
May be any of primary and tertiary amines, and may be linear, branched, or cyclic, and the linear amines may have an alicyclic or aromatic ring structure, and may have one or more amino groups. Although each may have one, the following [A] to
Those shown in [VIII] are preferably used.

As the primary amine, for example, the following formula [A]: H ₂ N- (CH ₂ CH ₂ NH) _n -H ... [A] [In the formula [A], n is an integer of 2 or more. , Preferably an integer of 2 to 4. ], And specific examples thereof include triethylenetetramine (n = 3).

Examples of the secondary amine (cyclic) include, for example, the following formula [F] (R ¹⁷ = H) and tertiary amine (cyclic):
For example, the following formula [F] (R17 ≠ H):

[0045]

[Chemical 6]

[In the formula [F], R ¹⁷ , R ¹⁸ and R ¹⁹ are each independently hydrogen, a carbon number of 1 to 20, preferably 1 to 3).
A linear or branched alkyl group, a cyanoethyl group,
An aminoethyl group, a cyanoethylaminoethyl group, a trimellitate group, a diaminotriazinylethyl group, a benzyl group, a phenyl group and the like are shown. ], Specifically, for example, 2-ethyl-4-methylimidazole, 4-ethyl-
2-methylimidazole, 2,4-dimethylimidazole, 2,4-diethylimidazole, imidazole, 2-
Methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and the like can be mentioned, preferably 2-ethyl-4-methylimidazole, 4-ethyl-2-methylimidazole and 2 ，
4-Dimethylimidazole and 2,4-diethylimidazole are used.

As the tertiary amine (chain), for example, the following formula [G]:

[0048]

[Chemical 7]

[In the formula [G], R ²⁰ , R ²¹ and R ²² each independently represent a chain or branched alkyl group having 1 to 20 carbon atoms, preferably about 4 to 15 carbon atoms, preferably R ²⁰ ,
R ²¹ and R ²² are all the same group. ], Specifically, for example, trioctylamine (R ²⁰ , R ²¹ , R ²²
= C ₈ H ₁₅ group), triethylamine (R ²⁰ , R ²¹ , R ²²
= C ₂ H ₅ group), tri-n-butylamine (R ²⁰ , R ²¹ , R
²² = n-C ₄ H ₉ group) and the like.

Further, as the tertiary amine (cyclic), for example, the following formula [H]:

[0051]

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[In the formula [H], u, v and w each independently represent an integer of about 1 to 5, preferably about 1 to 3, and preferably u, v and w are the same number. ], Specifically, for example, triethylenediamine (u,
v, w = 2: 1,4-diazabicyclo [2.2.0] octane) and the like, as well as DBU represented by the following formula (a)
(1,8-diazabicyclo [5.4.0] -7-undecene), DBN (1,5-diazabicyclo [4.3.0] -5-nonene) represented by the following formula (II) and the like can be mentioned.

[0053]

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In the present invention, these amines may be used either individually or in combination of two or more. Among the above amines, especially trioctylamine, triethylenetetramine, triethylenediamine, 2-ethyl-
4-methylimidazole and the like are preferably used.

The amines are usually used in an amount of 0.2 to 2 equivalents, preferably 0.3 to 1.0 equivalents, relative to 1 equivalent of hydrolyzable chlorine (1 mol of chlorine atom). If the amount of the amines used is less than 0.2 equivalent relative to 1 equivalent of hydrolyzable chlorine, the addition effect is scarcely seen, while if it exceeds 2 equivalents, the following undesirable side reactions easily occur. .

That is, when the amount of amine is too large compared to the above-mentioned amount of hydrolyzable chlorine, the system becomes remarkably basic and the polymerization reaction of the isocyanate compound (N = The C double bond is cleaved to form a single bond, and the C atom and the N atom are bonded to the N atom and the C atom of the adjacent isocyanate groups, respectively, to form a cyclic compound composed of three isocyanate compounds. Generation) will occur.

[0057]

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If the amount of the primary or secondary amine is too much compared with the above amount of hydrolyzable chlorine, the following reaction will occur:

[0059]

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[The above-mentioned wavy line portions respectively indicate the portions (residues) of the isocyanate compound other than the isocyanate group and the portions (residues) of the amines other than the amino group. ]
A large amount of urea is formed, and the isocyanate compound is C
In the case where it has a C bond (carbon / carbon double bond), C =
Those having a plurality of C bonds are generated, which causes gelation.

The number of equivalents of this amine is calculated by the following method. That is, 1 mol of amines is calculated by using the number of mols of N (nitrogen) atoms constituting the amine as its equivalent number.

For example, triethylenetetramine: NH _2-
In (CH ₂ ) ₂ —NH— (CH ₂ ) ₂ —NH— (CH ₂ ) ₂ —NH ₂ , the number of N atoms is 4 (4 mol atoms), and thus 4 equivalents. Also, with 2-methyl-4-ethylimidazole,
Since the number of N atoms is 2 (2 mol atom), it is 2 equivalents.

Since most of the hydrolyzable chlorine in the crude isocyanate can be changed to HCl, even if amines are used in such an environment, it becomes a hydrochloride, which has no effect. Contrary to most expectations that this is the case, in the present invention, since amines are used together with the epoxy compound in the purification of the isocyanate compound in this way, the purified isocyanate compound having a significantly reduced hydrolyzable chlorine content. Has been obtained.

Actually, when amines are not used in the purification of the isocyanate compound, there is a limit to the decrease of the content of hydrolyzable chlorine, and it is not more than a certain degree (eg, it depends on the type of the isocyanate compound, but for example, In the case of ethyl methacrylate, it is extremely difficult to adjust it to 1000 ppm% or less). However, in the present invention in which amines are used together with an epoxy compound in the purification of an isocyanate compound, it exceeds such a limit in the isocyanate compound. The content of hydrolyzable chlorine in water [for example, the content of hydrolyzable chlorine in the purified isocyanate compound: 20
It can be reduced to 0 ppm or less, preferably about 25 to 50 ppm].

It is assumed that this is because, for example, the following reactions occur.

[0066]

[Chemical 12]

Further, primary amines or secondary amines are liable to react with isocyanate, and if such a compound is used, the yield of isocyanate will be adversely affected, and most of the effects will be lost. Contrary to expectations,
According to the invention, it has surprisingly been found that the distillation yield of the isocyanate compound after removal of chlorine is not adversely affected by the addition of amines.

In addition, the viscosity of the residual liquid after distillation is lower than that in the case where amines are not used, the handling thereof is easy, and it is also convenient for increasing the recovery rate of isocyanate. ing.

In the present invention, the crude isocyanate compound containing such hydrolyzable chlorine is contained in an amount of 1 to 5 equivalents, preferably 1.5 to 3 equivalents, per equivalent of hydrolyzable chlorine. An epoxy compound and 0.2 to 2 equivalents, preferably 0.3 to 1.0 equivalents of the above amines are added and reacted with hydrolyzable chlorine under heating to obtain a purified isocyanate compound. ing.

The reaction temperature is usually set to 40 ° C to 150 ° C. Particularly, in the case of purifying an isocyanate compound having a polymerizable double bond, the temperature is set to 40 to 100 ° C., and in the case of purifying an isocyanate compound having no polymerizable double bond, 60 to 120. It is preferable to set the temperature to ° C.

The treatment (reaction) time is not particularly limited because it does not affect the effect so much, but it is suitable to carry out the treatment for about 30 minutes to 3 hours. When the difference in boiling point between the isocyanate compound and the epoxy compound used is small and the distillation method cannot be adopted, extraction or other method suitable for each compound may be used for purification.

[0072]

Industrial Applicability According to the method for purifying an isocyanate compound according to the present invention, the hydrolyzable chlorine contained in the crude isocyanate compound can be used industrially without adversely affecting the yield and quality of the isocyanate compound. Can be easily removed.

According to the present invention, in particular, it is possible to efficiently remove and purify hydrolyzable chlorine in crude aliphatic isocyanate, which has been conventionally difficult to remove hydrolyzable chlorine. It is suitable for purification of an isocyanate compound having

[0074]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is in no way limited by these examples. [Quantitative Method of Hydrolyzable Chlorine Content] In the following Examples and Comparative Examples, the hydrolyzable chlorine content in the crude or purified isocyanate compound is 1/100 normal concentration after reacting the isocyanate compound with methanol. It was measured by titration using a silver nitrate solution of. [Quantitative Method of Oxylan Oxygen Content in Epoxy Compound ] The oxirane oxygen content in the epoxy compound is quantified as follows.

That is, HCl and the epoxy compound
By reacting with epoxy group,
Determine the amount of xylan oxygen. Specifically, 2-4 mg equivalent
Take a sample of 200 ml in a Erlenmeyer flask with a stopper of 200 ml, and
ml of 0.2N HCl / dioxane solution was added,
Allow to react for 15-30 minutes at room temperature. Then 10 ml
Wash the inner wall of the flask and the stopper with methyl cellosolve, and add 0.1N
Concentration of NaOH / ethanol / methyl cellosolve solution
Titrate. Difference between this titration value and the blank test titration value
Calculate the oxirane oxygen content from. [Coarse (2-isocyanatoethylmethacrylate) tone
Made As shown in the following formula, 2-isopropenyloxazo
By reacting phosphorus and phosgene, the main raw material represented by the following formula
In addition to 2-isocyanatoethyl methacrylate, which is a product,
Crude (2-isocyanato containing biologically hydrolyzable chlorine
Ethyl methacrylate) was obtained.

[0076]

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More specifically, 1 liter of dichloromethane (solvent) was cooled to 0 ° C., and (1): 2-
A solution of 1 kg of isopropenyl oxazoline dissolved in 1.77 liters of water, (2): a solution of 1.35 kg of phosgene dissolved in 4 liters of dichloromethane, and (3): 2.5 liters of a 35% strength aqueous NaOH solution were added dropwise at the same time. did.

During this period, the temperature inside the system was maintained at 15 ° C. or lower. As a result, the reaction solution was separated into two phases. Then, the dichloromethane phase was separated and washed twice with 1 liter of saturated aqueous sodium hydrogen carbonate. Then, it was dried over sodium sulfate (anhydrous) and then distilled to obtain 1.0 kg of crude (isocyanatoethyl methacrylate).

[0079]

Example 1 A glass reactor having a capacity of 500 ml equipped with a fractionating tube, a thermometer, a stirrer, and a heating bath was charged with crude (2-isocyanatoethyl methacrylate / boiling point: 211) having a hydrolyzable chlorine content of 3153 ppm. ) 300 g, oxirane oxygen 6.1% epoxidized fat-based plasticizer [molecular weight: about 1000, iodine value: 7] 14 g, triethylene tetramine (boiling point 277.4 ℃) 0.91 g was charged, 6
After heating at 0 ℃ for 2.5 hours, about 10mmHg, 85 ℃
Then, about 250 g of purified (2-isocyanatoethyl methacrylate) was distilled.

10 g of the (purified) isocyanate compound obtained above was placed in a 200 ml Erlenmeyer flask equipped with a reflux condenser and a heating bath, and 10 ml of water and 90 ml of methanol were added to the (purified) isocyanate compound.
Milliliter was added and refluxed for 1 hour. Then, to this mixture was added a methanol / water mixture solution in which the inner tube of the reflux condenser was washed, 1 ml of 1: 1 nitric acid was further added, and the mixture was titrated with a 1 / 100N silver nitrate solution to determine the hydrolyzable chlorine content. It was 124 ppm.

[0081]

Comparative Example 1 The same treatment as in Example 1 was carried out except that triethylenetetramine was not used, and the hydrolyzability in the distillate [purified (2-isocyanatoethylmethacrylate)] was obtained. The chlorine content was 448 ppm.

[0082]

Reference Example 1 The same treatment as in Example 1 was carried out except that triethylenetetramine was used in an amount of 0.15 g, and a distillate [purified (2-isocyanatoethyl methacrylate)] was obtained. The content of hydrolyzable chlorine is 40
It was 1 ppm.

[0083]

[Reference Example 2] The same treatment as in Example 1 was carried out except that triethylenetetramine was used in an amount of 2.0 g in Example 1, and the temperature in the container began to rise during distillation.
The contents have polymerized.

[0084]

Example 2 Using the same apparatus as in Example 1, 300 g of 2-isocyanatoethyl methacrylate having a hydrolyzable chlorine content of 498 ppm and an epoxidized fatty acid ester plasticizer having oxirane oxygen of 4.7% [molecular weight: about 500, Iodine number: 4] 2.81 g, and trioctylamine 0.5
Charge 6 g and reflux under reduced pressure of 10 mmHg for 1 hour (re
flux). Next, switch the cock of the fractionating pipe to about 25
When 0 g was distilled, the content of hydrolyzable chlorine in this was 31 ppm.

[0085]

[Comparative Example 2] The same operation as in Example 2 was carried out except that trioctylamine was not used, and the amount of hydrolyzable chlorine in the obtained distillate was 422 ppm.
Met.

[0086]

Example 3 Using the same apparatus as in Example 1, 300 g of hexamethylene diisocyanate having a hydrolyzable chlorine content of 366 ppm, 2.1 g of the plasticizer used in Example 2, 2-ethyl-4-methylimidazole 0 Charge 0.1 g, 10
Heated at 0 ° C. for 1 hour. Next, it was distilled under a reduced pressure of 10 mmHg to obtain about 250 g of hexamethylene diisocyanate. The content of hydrolyzable chlorine in this was 34 ppm.

[0087]

COMPARATIVE EXAMPLE 3 In Example 3, direct distillation was carried out without using the plasticizer and 2-ethyl-4-methylimidazole, and the hydrolyzable chlorine concentration in the obtained purified hexamethylene diisocyanate was 84 ppm. there were.

[0088]

[Example 4] In Example 1, 300 g of 2-isocyanatoethyl methacrylate having a hydrolyzable chlorine content of 1126 ppm, 6.5 g of the same plasticizer as in Example 2 and 0.25 g of triethylenediamine were used and treated at 70 ° C. When the same treatment as in Example 1 was carried out except for the above, the hydrolyzable chlorine content in the distillate was 118 ppm.

Claims (3)

[Claims] 1. An isocyanate compound having a reduced content of hydrolyzable chlorine is obtained by treating a crude isocyanate compound containing hydrolyzable chlorine with an epoxy compound in the presence of amines. A method for purifying an isocyanate compound, comprising: 2. The amines are trialkylamine (wherein the alkyl group has 4 to 15 carbon atoms), a compound represented by the following formula [A] and 2-alkyl-4-alkylimidazole (however. The carbon number of the alkyl group is 1 to 3 independently of each other.) At least one compound selected from the above.
Method according _{to: H 2 N- (CH 2 CH} 2 NH) n -H ···· [A] ( wherein [A], n represents an integer of 2 or more.). 3. The amines are hydrolyzable chlorine of 0.2-2.
The method according to claim 1, wherein the method is used in a double equivalent amount.