JP5563816B2 - Treatment method of isocyanate residue - Google Patents

Description

  The present invention relates to a method for treating an isocyanate residue, and more particularly, to a method for treating an isocyanate residue in which an isocyanate residue obtained from a carbamate decomposition solution is decomposed into amines.

Isocyanate is a compound having at least one isocyanate group (—NCO), and is widely used industrially as a raw material for polyurethane, polyurea and the like.
Conventionally, isocyanate is industrially produced from the reaction of amine and phosgene (phosgene method), but phosgene is highly toxic and cumbersome to handle, and also produces a large amount of hydrochloric acid as a by-product. There are various problems, such as the need to consider the corrosion of the equipment, and development of an industrial production method of an isocyanate to replace this is desired.

As a method for producing an isocyanate without using phosgene, for example, a method in which an amine is carbamated with a dialkyl carbonate and then the obtained carbamate is thermally decomposed (carbonate method), or an amine is urea or N-unsubstituted carbamic acid ester. A method of thermally decomposing the obtained carbamate after conversion to carbamate (urea method) is known.
According to such a method, carbamate can be produced without using phosgene and decomposed into isocyanate and alcohol.

On the other hand, in the carbonate method and the urea method, it is known that the carbamates and isocyanates produced, or intermediates thereof, cause unfavorable polymerization reactions such as multimerization, biuretization and allophanate formation. .
In such a case, when isocyanate and alcohol are separated and recovered from the carbamate decomposition solution, by-products such as urea derivatives (biuret bodies) and carbamate derivatives (allophanate bodies) are obtained as isocyanate residues.

On the other hand, in the phosgene method, an isocyanate can be produced by a reaction between an amine and phosgene. However, in this method as well, an undesirable polymerization reaction such as an increase in the amount of isocyanate is caused. Obtained as a residue.
Such an isocyanate residue is usually disposed of, but in recent years, it has been required to reduce the amount of the treated waste from the viewpoint of the global environment. Therefore, there is a method for effectively using the recovered isocyanate residue. Various studies have been made. As such a method, for example, a residue produced as a by-product when an isocyanate compound is produced by the phosgene method is continuously supplied to the reactor in a molten state or a solution state, and high-pressure high-temperature water is continuously supplied to the reactor. And the temperature in the reactor is set to 190 to 300 ° C., and the residue is decomposed into polyamines and recovered (see, for example, Patent Document 1).

JP-A-10-279539

However, in the method described in Patent Document 1, although the isocyanate residue by-produced in the phosgene method can be decomposed into amines, on the other hand, it is not by-produced in the phosgene method and is by-produced in the carbonate method or urea method. There is a problem that residues (for example, urea derivatives, carbamate derivatives, etc.) cannot be decomposed.
The objective of this invention is providing the processing method of the isocyanate residue which can decompose | disassemble the isocyanate residue obtained from the decomposition liquid of carbamate into an amine.

In order to achieve the above object, the method for treating an isocyanate residue of the present invention comprises contacting an isocyanate residue obtained by separating isocyanate and alcohol from a decomposition solution obtained by a thermal decomposition reaction of carbamate with high-pressure high-temperature water in the presence of a solvent. It is characterized by decomposing into amines.
Moreover, in the processing method of the isocyanate residue of this invention, it is suitable that a solvent is aromatic hydrocarbons whose boiling point is 250 degreeC or more.

In the method for treating an isocyanate residue of the present invention, it is preferable that the carbamate is a carbamate produced by a reaction between an amine, urea and / or an N-unsubstituted carbamic acid ester, and an alcohol.
In the method for treating an isocyanate residue of the present invention, the amine used for the production of the carbamate is an amine obtained by decomposing the isocyanate residue, and the alcohol used for the production of the carbamate is obtained by a thermal decomposition reaction of the carbamate. The alcohol is preferably separated from the decomposition solution.

  Moreover, in the processing method of the isocyanate residue of this invention, after decomposing | disassembling an isocyanate residue, it is suitable to collect | recover a solvent and to thermally decompose carbamate in presence of the solvent collect | recovered after decomposing | disassembling an isocyanate residue.

According to the method for treating an isocyanate residue of the present invention, an isocyanate residue obtained from a carbamate decomposition solution can be decomposed into an amine.
Furthermore, according to the method for treating an isocyanate residue of the present invention, the isocyanate residue can be decomposed into an amine that is a raw material for producing carbamate, so that the cost for producing the isocyanate can be reduced.

It is a schematic block diagram which shows one Embodiment of the plant by which the processing method of the isocyanate residue of this invention is employ | adopted.

In the method for treating an isocyanate residue of the present invention, the isocyanate residue can be obtained by separating isocyanate (described later) and alcohol (described later) from a decomposition solution obtained by carbamate thermal decomposition reaction, which will be described in detail later. it can.
A carbamate is a compound having at least one urethane bond (—NHCOO—) in the molecule, and is represented by, for example, the following general formula (1).

R ^1- (NHCOOR ² ) n (1)
(In the formula, R ¹ is an aliphatic hydrocarbon group having 1 to 15 carbon atoms in total, an alicyclic hydrocarbon group having 3 to 15 carbon atoms, or an aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms in total. R ² represents an aliphatic hydrocarbon group having 1 to 16 carbon atoms in total or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total, and n represents an integer of 1 to 6).
In the above formula (1), R ¹ is an aliphatic hydrocarbon group having 1 to 15 carbon atoms in total, an alicyclic hydrocarbon group having 3 to 15 carbon atoms in total, and an aromatic ring containing 6 to 15 carbon atoms in total. R ¹ is selected from hydrocarbon groups, and R ¹ may contain a stable bond such as an ether bond, a thioether bond, or an ester bond in the hydrocarbon group, or a stable functional group (described later). ) May be substituted.

In R ^1, examples of the aliphatic hydrocarbon group having a total carbon number of 1 to 15, for example, like 1-6 monovalent, linear or branched total aliphatic hydrocarbon group having 1 to 15 carbon atoms .
More specifically, examples include an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 1 to 15 carbon atoms, and an alkylidene group having 1 to 15 carbon atoms.
Examples of the alkyl group include methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, iso-pentyl, sec-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl. , Nonyl, decyl, isodecyl, dodecyl, tetradecyl and the like.

Examples of the alkenyl group include propenyl, butenyl, pentenyl and the like.
Examples of the alkylidene group include ethylidene, propylidene, butylidene, pentylidene, and hexylidene.
In R ¹ , examples of the alicyclic hydrocarbon group having 3 to 15 carbon atoms include 1 to 6-valent alicyclic hydrocarbon groups having 3 to 15 carbon atoms.

  The alicyclic hydrocarbon group only needs to contain one or more alicyclic hydrocarbons in the hydrocarbon group. For example, the alicyclic hydrocarbon includes, for example, an aliphatic hydrocarbon group. Etc. may be combined. In such a case, the urethane bond (—NHCOO—) in the carbamate may be directly bonded to the alicyclic hydrocarbon or bonded to the aliphatic hydrocarbon group bonded to the alicyclic hydrocarbon. Or both of them.

More specifically, examples thereof include a cycloalkyl group having 3 to 15 carbon atoms in total.
Examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, cyclooctyl, dimethylcyclohexyl, isophorone, norbornene, decalin, adamantane, 4,4′-methylenebis (cyclohexane), 2,4′-methylenebis. (Cyclohexane), 1,4-cyclohexylidene and the like.

In R ¹ , examples of the aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms include 1 to 6-valent aromatic ring-containing hydrocarbon groups having 6 to 15 carbon atoms in total.
The aromatic ring-containing hydrocarbon group only needs to contain one or more aromatic hydrocarbons in the hydrocarbon group. For example, the aromatic hydrocarbon includes, for example, an aliphatic hydrocarbon group. It may be bonded. In such a case, the urethane bond (—NHCOO—) in the carbamate may be directly bonded to the aromatic hydrocarbon or may be bonded to the aliphatic hydrocarbon group bonded to the aromatic hydrocarbon. Well, both may be sufficient.

More specifically, for example, an aryl group having 6 to 15 carbon atoms in total can be used.
Examples of the aryl group include phenyl, tolyl, xylyl, naphthyl, biphenyl, anthryl, trimethylphenyl, 4,4′-methylenebisphenylene, phenanthryl and the like.
In the above formula (1), examples of the functional group which may be substituted on R ¹ include a nitro group, a hydroxyl group, a mercapto group, an oxo group, a thioxo group, a cyano group, a carboxy group, and an alkoxy-carbonyl group (for example, Methoxycarbonyl group, alkoxycarbonyl group having 2 to 4 total carbon atoms such as ethoxycarbonyl group), sulfo group, halogen atom (for example, fluorine, chlorine, bromine, iodine, etc.), lower alkoxy group (for example, methoxy group, ethoxy group) , Propoxy group, butoxy group, iso-butoxy group, sec-butoxy group, tert-butoxy group, etc.), aryloxy group (for example, phenoxy group), halogenophenoxy group (for example, o-, m-, or p-chloro) Phenoxy group, o-, m- or p-bromophenoxy group), lower alkylthio group (eg For example, a methylthio group, an ethylthio group, an n-propylthio group, an iso-propylthio group, an n-butylthio group, a tert-butylthio group, etc., an arylthio group (eg, a phenylthio group), a lower alkylsulfinyl group (eg, a methylsulfinyl group) , Ethylsulfinyl group etc.), lower alkylsulfonyl group (eg methylsulfonyl group, ethylsulfonyl group etc.), arylsulfonyl group (eg phenylsulfonyl etc.), lower acyl group (eg formyl group, acetyl group etc.), aryl Examples thereof include a carbonyl group (for example, a benzoyl group).

In the above formula (1), a plurality of these functional groups may be substituted with R ^1, and when the functional group is substituted with R ¹ , each functional group may be the same as each other. , Each may be different.
In the above formula (1), in R ² , examples of the aliphatic hydrocarbon group having 1 to 16 carbon atoms include an alkyl group having 1 to 16 carbon atoms.

Examples of the alkyl group include the above-described alkyl groups.
In the above formula (1), in R ² , examples of the aromatic hydrocarbon group having 6 to 16 carbon atoms include an aryl group having 6 to 16 carbon atoms.
Examples of the aryl group include the above-described aryl groups.
In the above formula (1), n represents an integer of 1 to 6, preferably 1 or 2, and more preferably 2.

  Specific examples of such carbamates include methyl hexyl carbamate, methyl octyl carbamate, methyl dodecyl carbamate, methyl octadecyl carbamate, 1,4-bis (methoxycarbonylamino) butane, 1,4-bis (ethoxycarbonylamino). ) Butane, 1,4-bis (butoxycarbonylamino) butane, 1,5-bis (methoxycarbonylamino) pentane, 1,5-bis (butoxycarbonylamino) pentane, 1,6-bis (methoxycarbonylamino) hexane 1,6-bis (ethoxycarbonylamino) hexane, 1,6-bis (butoxycarbonylamino) hexane, 1,8-bis (methoxycarbonylamino) octane, 1,8-bis (butoxycarbonylamino) octane, , 8 Bis (phenoxycarbonylamino) -4- (phenoxycarbonylaminomethyl) octane, 1,9-bis (methoxycarbonylamino) nonane, 1,9-bis (butoxycarbonylamino) nonane, 1,10-bis (methoxycarbonylamino) ) -Decane, 1,12-bis (butoxycarbonylamino) -dodecane, 1,12-bis (methoxycarbonylamino) -dodecane, 1,12-bis (phenoxycarbonylamino) -dodecane, 2,2′-bis ( Aliphatic carbamates such as 4-propoxycarbonylaminophenyl) propane, 1,3,6-tris (methoxycarbonylamino) hexane, 1,3,6-tris (phenoxycarbonylamino) hexane, such as 1,3- or 1,4-bis (methoxycarbonylamino) Cyclohexane, 1,3- or 1,4-bis (ethoxycarbonylamino) cyclohexane, 1,3- or 1,4-bis (butoxycarbonylamino) cyclohexane, 1,3- or 1,4-bis (methoxycarbonylamino) Methyl) cyclohexane, 1,3- or 1,4-bis (ethoxycarbonylaminomethyl) cyclohexane, 1,3- or 1,4-bis (butoxycarbonylaminomethyl) cyclohexane, 2,4′- or 4,4 ′ -Bis (ethoxycarbonylamino) dicyclohexanemethane, 2,4'- or 4,4'-bis (phenoxycarbonylamino) dicyclohexylmethane, 2,4'- or 4,4'-bis (methoxycarbonylamino) dicyclohexylmethane 2,4′- or 4,4′-bis (B Toxicarbonylamino) dicyclohexylmethane, 2,5-bis (methoxycarbonylaminomethyl) bicyclo [2,2,1] heptane, 2,5-bis (butoxycarbonylaminomethyl) bicyclo [2,2,1] heptane, 2 , 6-Bis (methoxycarbonylaminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (butoxycarbonylaminomethyl) bicyclo [2,2,1] heptane, 1- (methoxycarbonylamino) -3 , 3,5-trimethyl-5- (methoxycarbonylaminomethyl) -cyclohexane, 1- (butoxycarbonylamino) -3,3,5-trimethyl-5- (butoxycarbonylaminomethyl) -cyclohexane, 3-methoxycarbonylamino Methyl-3,5,5-trimethyl-1-methoxycarbo Alicyclic carbamates such as ruaminocyclohexane, 4,4′-bis (methoxycarbonylamino) -2,2′-dicyclohexylpropane, 4,4′-bis (butoxycarbonylamino) -2,2′-dicyclohexylpropane For example, 1,3- or 1,4-bis (methoxycarbonylaminomethyl) benzene, 1,3- or 1,4-bis (ethoxycarbonylaminomethyl) benzene, 1,3- or 1,4-bis ( Butoxycarbonylaminomethyl) benzene, 1,3- or 1,4-bis (methoxycarbonylamino) benzene, 1,3- or 1,4-bis (butoxycarbonylamino) benzene, 2,4′- or 4,4 '-Bis (methoxycarbonylamino) diphenylmethane, 2,4'- or 4,4'-bis ( Toxicarbonylamino) diphenylmethane, 2,4′- or 4,4′-bis (butoxycarbonylamino) diphenylmethane, 4,4′-bis (phenoxycarbonylamino) diphenylmethane, 1,5- or 2,6-bis (methoxy) Carbonylamino) naphthalene, 1,5- or 2,6-bis (butoxycarbonylamino) naphthalene, 4,4′-bis (methoxycarbonylamino) biphenyl, 4,4′-bis (butoxycarbonylamino) biphenyl, 2, Such as 4- or 2,6-bis (methoxycarbonylamino) toluene, 2,4- or 2,6-bis (ethoxycarbonylamino) toluene, 2,4- or 2,6-bis (butoxycarbonylamino) toluene, etc. Aromatic carbamates and the like can be mentioned. These carbamates may be used alone or in combination of two or more.

Such carbamates are not particularly limited, but are produced by, for example, a carbonate method, a urea method, or the like according to the above specific compound. Preferably, it is produced by the urea process, i.e., reaction of an amine with urea and / or N-unsubstituted carbamic acid ester with an alcohol.
Examples of amines include primary amines.

The primary amine is an amino group-containing organic compound having one or more primary amino groups, and is represented by, for example, the following general formula (2).
R ^1- (NH ₂ ) n (2)
(Wherein, ^{R 1} is the same meaning as ^{R 1} in the formula (1), n represents the same meaning as n in formula (1).)
In the above formula (2), ^{R 1, R 1} and as defined in the formula (1), namely, a total carbon number of 1 to 15 aliphatic hydrocarbon group, the total carbon number of 3 to 15 alicyclic-containing hydrocarbon And an aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms in total. R ¹ may include a stable bond such as an ether bond, a thioether bond, or an ester bond in the hydrocarbon group, or may be substituted with the above-described stable functional group. .

In R ¹ , examples of the aliphatic hydrocarbon group having 1 to 15 carbon atoms in total include 1 to 6 valent linear or branched aliphatic hydrocarbon groups having 1 to 15 carbon atoms in total. Is mentioned.
In the above formula (2), examples of the primary amine in which R ¹ is an aliphatic hydrocarbon group having 1 to 15 carbon atoms include aliphatic amines having 1 to 15 carbon atoms.

  Examples of such aliphatic amines include methylamine, ethylamine, n-propylamine, iso-propylamine, butylamine, pentylamine, hexylamine, n-octylamine, 2-ethylhexylamine, decylamine, dodecylamine, tetra Linear or branched aliphatic primary monoamines such as decylamine, such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane (1,4-tetramethylenediamine), 1 , 5-diaminopentane (1,5-pentamethylenediamine), 1,6-diaminohexane (1,6-hexamethylenediamine), 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane 1,10-diaminodecane, 1,12-diaminododecane, , 2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, aliphatic primary diamine such as tetramethylenediamine, for example, 1,2,3-triaminopropane, triaminohexane, triamino Nonane, triaminododecane, 1,8-diamino-4-aminomethyloctane, 1,3,6-triaminohexane, 1,6,11-triaminoundecane, 3-aminomethyl-1,6-diaminohexane, etc. And aliphatic primary triamines.

In R ¹ , examples of the alicyclic hydrocarbon group having 3 to 15 carbon atoms include the 1 to 6-valent alicyclic hydrocarbon groups having 3 to 15 carbon atoms described above.
As described above, the alicyclic hydrocarbon group only needs to contain one or more alicyclic hydrocarbons in the hydrocarbon group. For example, the alicyclic hydrocarbon includes, for example, an aliphatic group. A group hydrocarbon group or the like may be bonded. In such a case, the amino group in the primary amine may be directly bonded to the alicyclic hydrocarbon, or may be bonded to the aliphatic hydrocarbon group bonded to the alicyclic hydrocarbon. Or both.

In the above formula (2), examples of the primary amine in which R ¹ is an alicyclic hydrocarbon group having 3 to 15 carbon atoms include alicyclic amines having 3 to 15 carbon atoms.
Examples of such alicyclic amines include alicyclic primary monoamines such as cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, and hydrogenated toluidine, such as diaminocyclobutane, isophoronediamine (3-aminomethyl- 3,5,5-trimethylcyclohexylamine), 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4 -Bis (aminomethyl) cyclohexane, 4,4'-methylenebis (cyclohexylamine), 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (aminomethyl) bicyclo [ 2,2,1] heptane, hydrogenated 2,4-tolylenediamine, hydrogenated Examples include alicyclic primary diamines such as 2,6-tolylenediamine, and alicyclic primary triamines such as triaminocyclohexane.

Examples of the aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms in R ¹ include the 1 to 6-valent aromatic ring-containing hydrocarbon groups having 6 to 15 carbon atoms as described above.
As described above, the aromatic ring-containing hydrocarbon group only needs to contain one or more aromatic hydrocarbons in the hydrocarbon group. For example, the aromatic hydrocarbon includes, for example, an aliphatic carbon A hydrogen group or the like may be bonded. In such a case, the amino group in the primary amine may be directly bonded to the aromatic hydrocarbon, or may be bonded to the aliphatic hydrocarbon group bonded to the aromatic hydrocarbon. Both may be used.

In the above formula (2), examples of the primary amine in which R ¹ is an aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms include aromatic amines having 6 to 15 carbon atoms and 6 to 15 carbon atoms. And araliphatic amines.
Examples of such aromatic amines include aniline, o-toluidine (2-methylaniline), m-toluidine (3-methylaniline), p-toluidine (4-methylaniline), 2,3-xylidine (2 , 3-dimethylaniline), 2,4-xylidine (2,4-dimethylaniline), 2,5-xylidine (2,5-dimethylaniline), 2,6-xylidine (2,6-dimethylaniline), 3 Aromatic primary monoamines such as 1,4-xylidine (3,4-dimethylaniline), 3,5-xylidine (3,5-dimethylaniline), 1-naphthylamine, 2-naphthylamine, for example, 2,4-tolylene Amine (2,4-diaminotoluene), 2,6-tolylenediamine (2,6-diaminotoluene), 4,4'-diphenylmethanediamine 2,4′-diphenylmethanediamine, 2,2′-diphenylmethanediamine, 4,4′-diphenyletherdiamine, 2-nitrodiphenyl-4,4′-diamine, 2,2′-diphenylpropane-4,4′-diamine 3,3′-dimethyldiphenylmethane-4,4′-diamine, 4,4′-diphenylpropanediamine, m-phenylenediamine, p-phenylenediamine, naphthylene-1,4-diamine, naphthylene-1,5-diamine And aromatic primary diamines such as 3,3′-dimethoxydiphenyl-4,4′-diamine.

  Examples of such araliphatic amines include araliphatic primary monoamines such as benzylamine, such as 1,3-bis (aminomethyl) benzene, 1,4-bis (aminomethyl) benzene, 1,3. -Tetramethylxylylenediamine (1,3-di (2-amino-2-methylethyl) benzene), 1,4-tetramethylxylylenediamine (1,4-bis (2-amino-2-methylethyl) And aromatic aliphatic primary diamines such as benzene).

In the above formula (2), n has the same meaning as R ^{1 in the} above formula (1), that is, for example, an integer of 1 to 6, preferably 1 or 2, and more preferably 2. .
These primary amines can be used alone or in combination of two or more.
The primary amine is preferably a primary amine in which R ¹ is an aromatic ring-containing hydrocarbon group having a total carbon number of 6 to 15 in the above formula (2), more specifically, a total carbon number of 6 -15 aromatic amines.

  Moreover, what becomes a manufacturing raw material of the isocyanate used industrially as a primary amine is also preferable, As such a primary amine, 1, 6- diaminohexane, isophorone diamine, 1, 3-bis (aminomethyl) is preferable, for example. ) Cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexylamine), 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6 -Bis (aminomethyl) bicyclo [2,2,1] heptane, 2,4-tolylenediamine (2,4-diaminotoluene), 2,6-tolylenediamine (2,6-diaminotoluene), 4, 4'-diphenylmethanediamine, 2,4'-diphenylmethanediamine, 2,2'-diphenylmethanediamine, naphthylene-1,5-dia 1,3-bis (aminomethyl) benzene, 1,4-bis (aminomethyl) benzene, 1,3-tetramethylxylylenediamine, 1,4-tetramethylxylylenediamine, and the like are particularly preferable. Are isophoronediamine, 2,4-tolylenediamine (2,4-diaminotoluene), 2,6-tolylenediamine (2,6-diaminotoluene), 4,4'-diphenylmethanediamine, 2,4'- Diphenylmethanediamine, 2,2′-diphenylmethanediamine, naphthylene-1,5-diamine, 1,3-bis (aminomethyl) benzene, 1,4-bis (aminomethyl) benzene, 1,3-tetramethylxylylenediamine 1,4-tetramethylxylylenediamine.

Furthermore, although mentioned later in detail, As an amine used for the production | generation of such a carbamate, Preferably, the amine (after-mentioned) obtained by decomposing | disassembling an isocyanate residue (after-mentioned) is mentioned.
N-unsubstituted carbamic acid ester is a carbamic acid ester in which the nitrogen atom in the carbamoyl group is not substituted by a functional group (that is, the nitrogen atom is bonded to two hydrogen atoms and one carbon atom). For example, it is represented by the following general formula (3).

R ³ O—CO—NH ₂ (3)
(In the formula, R ³ represents an aliphatic hydrocarbon group having 1 to 16 carbon atoms in total or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total.)
In the above formula (3), in R ³ , examples of the aliphatic hydrocarbon group having 1 to 16 carbon atoms in total include the above-described alkyl groups.

Examples of the N-unsubstituted carbamic acid ester in which R ³ is an aliphatic hydrocarbon group having 1 to 16 carbon atoms in the above formula (3) include, for example, methyl carbamate, ethyl carbamate, propyl carbamate, and carbamic acid. iso-propyl, butyl carbamate, iso-butyl carbamate, sec-butyl carbamate, tert-butyl carbamate, pentyl carbamate, iso-pentyl carbamate, sec-pentyl carbamate, hexyl carbamate, heptyl carbamate, Examples include octyl carbamate, 2-ethylhexyl carbamate, nonyl carbamate, decyl carbamate, isodecyl carbamate, dodecyl carbamate, tetradecyl carbamate, hexadecyl carbamate, and the like.

In the above formula (3), in R ³ , examples of the aromatic hydrocarbon group having 6 to 16 carbon atoms in total include the above-described aryl groups.
In the above formula (3), examples of the N-unsubstituted carbamic acid ester in which R ³ is an aromatic hydrocarbon group having 6 to 16 carbon atoms include phenyl carbamate, tolyl carbamate, xylyl carbamate, and carbamic acid. Biphenyl, naphthyl carbamate, anthryl carbamate, phenanthryl carbamate and the like.

These N-unsubstituted carbamic acid esters can be used alone or in combination of two or more.
The N-unsubstituted carbamic acid ester is preferably an N-unsubstituted carbamic acid ester in which R ³ is an aliphatic hydrocarbon group having a total carbon number of 1 to 16 in the above formula (3), more preferably R ^3. Is an N-unsubstituted carbamic acid ester which is an aliphatic hydrocarbon group having 2 to 12 carbon atoms in total.

The alcohol is, for example, a primary to tertiary monohydric alcohol, and is represented by, for example, the following formula (4).
R ² —OH (4)
(Wherein, ^{R 2} is as defined for ^{R 2} in the formula (1).)
In the above formula (4), examples of the alcohol in which R ² is an aliphatic hydrocarbon group having 1 to 16 carbon atoms include methanol, ethanol, propanol, iso-propanol, butanol (1-butanol), and iso-butanol. , Sec-butanol, tert-butanol, pentanol, iso-pentanol, sec-pentanol, hexanol, heptanol, octanol (1-octanol), 2-ethylhexanol, nonanol, decanol, isodecanol, dodecanol, tetradecanol, Examples include hexadecanol.

In the above formula (4), examples of the alcohol in which R ² is an aromatic hydrocarbon group having 6 to 16 carbon atoms include phenol, hydroxytoluene, hydroxyxylene, biphenyl alcohol, naphthalenol, anthracenol, and phenol. Nantrenol and the like are listed.
These alcohols can be used alone or in combination of two or more.

The alcohol is preferably an alcohol in which R ² is an aliphatic hydrocarbon group having 1 to 16 carbon atoms in the above formula (4), more preferably an R ² is an aliphatic hydrocarbon group having 2 to 12 carbon atoms. Some alcohols are mentioned.
Moreover, although mentioned later in detail, As alcohol used for the production | generation of carbamate, Preferably alcohol (after-mentioned) isolate | separated from the decomposition liquid obtained by the thermal decomposition reaction of carbamate is mentioned.

In this method, the primary amine described above, urea and / or N-unsubstituted carbamic acid ester, and alcohol are blended and preferably reacted in a liquid phase.
The mixing ratio of the primary amine, urea and / or N-unsubstituted carbamic acid ester, and alcohol is not particularly limited and can be appropriately selected within a relatively wide range.
Usually, the compounding amount of urea and N-unsubstituted carbamic acid ester and the compounding amount of alcohol should be equimolar or more with respect to the amino group of the primary amine. Therefore, urea and / or N- An unsubstituted carbamate or alcohol itself can also be used as a reaction solvent in this reaction.

When urea and / or the above-mentioned N-unsubstituted carbamic acid ester or alcohol is also used as a reaction solvent, an excessive amount of urea and / or the above-mentioned N-unsubstituted carbamic acid ester or alcohol is used as necessary. However, if the excess amount is large, the energy consumption in the separation step after the reaction increases, which is not suitable for industrial production.
Therefore, the blending amount of urea and / or the above-mentioned N-unsubstituted carbamic acid ester is 0.5 to 20 times mol with respect to one amino group of the primary amine from the viewpoint of improving the yield of carbamate, Preferably, it is 1 to 10 times mol, more preferably about 1 to 5 times mol, and the compounding amount of alcohol is 0.5 to 100 times mol, preferably 1 to 1 amino group of primary amine, 1 to 20 times mol, more preferably about 1 to 10 times mol.

In this reaction, a reaction solvent is not always necessary. For example, when the reaction raw material is solid or a reaction product is precipitated, the operability can be improved by blending the reaction solvent.
Such a reaction solvent is inactive or reactive with respect to the primary raw material, urea and / or N-unsubstituted carbamic acid ester, which is a reaction raw material, alcohol, and carbamate, which is a reaction product. If it is scarce, it is not particularly limited. For example, aliphatic hydrocarbons (eg, hexane, pentane, petroleum ether, ligroin, cyclododecane, decalins, etc.), aromatic hydrocarbons (eg, benzene) , Toluene, xylene, ethylbenzene, isopropylbenzene, butylbenzene, cyclohexylbenzene, tetralin, chlorobenzene, o-dichlorobenzene, methylnaphthalene, chloronaphthalene, dibenzyltoluene, triphenylmethane, phenylnaphthalene, biphenyl, diethylbiphenyl, triethyl Phenyl), ethers (eg, diethyl ether, diisopropyl ether, dibutyl ether, anisole, diphenyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether), carbonates ( For example, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, etc.), nitriles (eg, acetonitrile, propionitrile, adiponitrile, benzonitrile, etc.), aliphatic halogenated hydrocarbons (eg, methylene chloride, chloroform, 1,2-dichloroethane, 1,2-dichloropropane, , 4-dichlorobutane), amides (eg, dimethylformamide, dimethylacetamide, etc.), nitro compounds (eg, nitromethane, nitrobenzene, etc.), N-methylpyrrolidinone, N, N-dimethylimidazolidinone, dimethyl sulfoxide Etc.

Of these reaction solvents, aliphatic hydrocarbons and aromatic hydrocarbons are preferably used in view of economy and operability. Moreover, such a reaction solvent can be used individually or in combination of 2 or more types.
Further, the amount of the reaction solvent is not particularly limited as long as the target product carbamate is dissolved, but industrially, it is necessary to recover the reaction solvent from the reaction solution. If the energy consumed for the recovery is reduced as much as possible and the blending amount is large, the reaction substrate concentration decreases and the reaction rate becomes slow. More specifically, it is used in the range of usually 0 to 500 parts by mass, preferably 0 to 100 parts by mass with respect to 1 part by mass of the primary amine.

In this reaction, the reaction temperature is appropriately selected, for example, in the range of 100 to 350 ° C, preferably 150 to 300 ° C. When the reaction temperature is lower than this, the reaction rate may decrease. On the other hand, when the reaction temperature is higher than this, the side reaction may increase and the yield of the target product carbamate may decrease.
The reaction pressure is usually atmospheric pressure, but may be increased when the boiling point of the component in the reaction solution is lower than the reaction temperature, and further reduced as necessary.

Moreover, reaction time is 0.1 to 20 hours, for example, Preferably, it is 0.5 to 10 hours. If the reaction time is shorter than this, the yield of the target product carbamate may decrease. On the other hand, if it is longer than this, it is unsuitable for industrial production.
In this method, a catalyst can also be used.
Although it does not restrict | limit especially as a catalyst, For example, lithium methanolate, lithium ethanolate, lithium propanolate, lithium butanolate, sodium methanolate, potassium tert-butanolate, magnesium methanolate, calcium methanolate, tin chloride ( II), tin chloride (IV), lead acetate, lead phosphate, antimony chloride (III), antimony chloride (V), aluminum acetylacetonate, aluminum-isobutyrate, aluminum trichloride, bismuth chloride (III), copper acetate ( II), copper sulfate (II), copper nitrate (II), bis- (triphenyl-phosphine oxide) -copper chloride (II), copper molybdate, silver acetate, gold acetate, zinc oxide, zinc chloride, zinc acetate, Zinc acetonyl acetate, zinc octoate, Zinc oxide, zinc hexylate, zinc benzoate, zinc undecylate, cerium (IV) oxide, uranyl acetate, titanium tetraisopropanolate, titanium tetrabutanolate, titanium tetrachloride, titanium tetraphenolate, titanium naphthenate, chloride Vanadium (III), vanadium acetylacetonate, chromium chloride (III), molybdenum oxide (VI), molybdenum acetylacetonate, tungsten oxide (VI), manganese chloride (II), manganese acetate (II), manganese acetate (III) , Iron (II) acetate, iron (III) acetate, iron phosphate, iron oxalate, iron (III) chloride, iron (III) bromide, cobalt acetate, cobalt chloride, cobalt sulfate, cobalt naphthenate, nickel chloride, Examples thereof include nickel acetate and nickel naphthenate.

Furthermore, as a catalyst, for example, Zn (OSO ₂ CF ₃ ) ₂ (another notation: Zn (OTf) ₂ , zinc trifluoromethanesulfonate), Zn (OSO ₂ C ₂ F ₅ ) ₂ , Zn (OSO ₂ C ₃ F ₇ ) ₂ , Zn (OSO ₂ C ₄ F ₉ ) ₂ , Zn (OSO ₂ C ₆ H ₄ CH ₃ ) ₂ (p-toluenesulfonic acid zinc), Zn (OSO ₂ C ₆ H ₅ ) ₂ , Zn ( BF ₄ ) ₂ , Zn (PF ₆ ) ₂ , Hf (OTf) ₄ (hafnium trifluoromethanesulfonate), Sn (OTf) ₂ , Al (OTf) ₃ , Cu (OTf) _{2 and the} like are also included.

These catalysts can be used alone or in combination of two or more.
Moreover, the compounding quantity of a catalyst is 0.000001-0.1 mol with respect to 1 mol of amines, Preferably, it is 0.00005-0.05 mol. Even if the amount of the catalyst is larger than this, no further significant reaction promoting effect is observed, but the cost may increase due to an increase in the amount of the catalyst. On the other hand, if the blending amount is less than this, the reaction promoting effect may not be obtained.

In addition, the addition method of a catalyst does not affect reaction activity in any addition method of lump addition, continuous addition, and a plurality of intermittent additions, and is not particularly limited.
In this reaction, for example, primary amine, urea and / or N-unsubstituted carbamic acid ester, alcohol, and, if necessary, a catalyst and a reaction solvent are charged in a reaction vessel under the above-described conditions, and stirred or mixed. do it. Then, for example, the carbamate which is the target product represented by the above formula (1) is produced in a short time, at a low cost and in a high yield under mild conditions.

The amount of carbamate produced by this reaction is, for example, 0.8 mol or more, preferably 0.85 mol or more, with respect to 1 mol of amine. That is, the carbamate is generated at a ratio of, for example, 80 mol% or more, preferably 85 mol% or more with respect to 1 mol of the amine.
In this reaction, ammonia is by-produced.

In this reaction, when N-unsubstituted carbamic acid ester is blended, for example, an alcohol represented by the following general formula (5) is by-produced.
R ³ —OH (5)
(In the formula, R ³ has the same meaning as R ^{3 in the} formula (3)).
In this reaction, either a batch type or a continuous type can be adopted as the reaction type.

In addition, this reaction is preferably carried out while allowing ammonia produced as a by-product to flow out of the system. Furthermore, when N-unsubstituted carbamic acid ester is blended, the reaction is carried out while distilling off the by-produced alcohol out of the system.
Thereby, the production | generation of the carbamate which is a target product can be accelerated | stimulated, and the yield can be improved further.

When the obtained carbamate is isolated, for example, excess (unreacted) urea and / or N-unsubstituted carbamic acid ester, excess (unreacted) alcohol, catalyst, carbamate, reaction solvent, side solvent, The carbamate may be separated from the reaction solution containing the produced ammonia and optionally by-produced alcohol by a known separation and purification method.
In this method, the obtained carbamate is thermally decomposed to produce isocyanate and alcohol.

That is, in this method, for example, the carbamate obtained by the above method is thermally decomposed, and the isocyanate represented by the following general formula (6) corresponding to the above primary amine, and
R ^1- (NCO) n (6)
(Wherein, ^{R 1} is the same meaning as ^{R 1} in the formula (1), n represents the same meaning as n in formula (1).)
An alcohol represented by the following general formula (7), which is a by-product, is generated.

R ² —OH (7)
(Wherein, ^{R 2} is as defined for ^{R 2} in the formula (4).)
This thermal decomposition is not particularly limited, and for example, a known decomposition method such as a liquid phase method or a gas phase method can be used.
In the gas phase process, the isocyanate and alcohol produced by pyrolysis can be separated from the gaseous product mixture by fractional condensation. In the liquid phase method, isocyanate and alcohol produced by thermal decomposition can be separated by using, for example, distillation or a solvent and / or an inert gas as a support material.

The thermal decomposition is preferably a liquid phase method from the viewpoint of workability.
In such a process, the carbamate is preferably pyrolyzed in the presence of an inert solvent.
The inert solvent is not particularly limited as long as it dissolves at least the carbamate, is inert with respect to the carbamate and isocyanate, and does not react during pyrolysis (ie, is stable). In order to implement efficiently, it is preferable that it is a boiling point higher than the isocyanate to produce | generate. Examples of such inert solvents include esters such as dioctyl phthalate, didecyl phthalate, and didodecyl phthalate, such as dibenzyltoluene, triphenylmethane, phenylnaphthalene, biphenyl, diethylbiphenyl, and triethylbiphenyl. Aromatic hydrocarbons and aliphatic hydrocarbons that are commonly used as media.

In addition, the inert solvent preferably includes the same type of solvent as used in the decomposition of the isocyanate residue (described later), and more preferably, after the isocyanate residue (described later) is decomposed, it is separated and recovered. Solvent (described later).
That is, preferably, the carbamate is thermally decomposed in the presence of a solvent (described later) recovered after decomposing an isocyanate residue (described later).

The compounding quantity of an inert solvent is 0.001-100 mass parts with respect to 1 mass part of carbamate, Preferably, it is 0.01-80 mass parts, More preferably, it is the range of 0.1-50 mass parts.
Further, since the carbamate thermal decomposition reaction in the liquid phase method is a reversible reaction, preferably, the reverse reaction of the thermal decomposition reaction (that is, the isocyanate represented by the general formula (6) and the general formula (7) In order to suppress the urethanation reaction with the indicated alcohol), the carbamate is thermally decomposed, and the isocyanate represented by the general formula (6) and / or the alcohol represented by the general formula (7) is removed from the reaction mixture. They are extracted by a known method and separated.

  As reaction conditions for the thermal decomposition reaction, preferably, the carbamate can be decomposed satisfactorily, and the isocyanate (the general formula (6)) and the alcohol (the general formula (7)) generated in the thermal decomposition are evaporated, Examples of the reaction conditions include that the carbamate and isocyanate are not in an equilibrium state, and further, side reactions such as polymerization of isocyanate are suppressed.

  More specifically, as such reaction conditions, the thermal decomposition temperature is usually 350 ° C. or lower, preferably 80 to 350 ° C., more preferably 100 to 300 ° C. When it is lower than 80 ° C., a practical reaction rate may not be obtained, and when it exceeds 350 ° C., undesirable side reactions such as polymerization of isocyanate may occur. In addition, the pressure during the pyrolysis reaction is preferably a pressure at which the generated alcohol can be vaporized with respect to the above pyrolysis reaction temperature. It is preferably 90 kPa.

  The carbamate used for the thermal decomposition may be purified, but after completion of the above reaction (that is, reaction of primary amine, urea and / or N-unsubstituted carbamic acid ester with alcohol), Excess (unreacted) urea and / or N-unsubstituted carbamic acid ester, excess (unreacted) alcohol, catalyst, reaction solvent, by-product ammonia, and optionally by-product alcohol were recovered and separated. The carbamate raw material may be used for subsequent thermal decomposition.

  Each component excluding the carbamate (excess (unreacted) urea and / or N-unsubstituted carbamic acid ester, excess (unreacted) alcohol, catalyst, reaction solvent, by-produced ammonia, and optionally by-product. The method for recovering alcohol etc. is not particularly limited, and examples thereof include vacuum distillation. In such a case, for example, each of the above components can be recovered as a light boiling component and carbamate can be separated as a heavy boiling component.

Further, in this method, a catalyst can be added if necessary.
The catalyst may be added to the reaction at the time of the above reaction, before or after the distillation separation after the reaction, or before or after the separation of the carbamate.
The catalyst used for the thermal decomposition is one or more selected from Sn, Sb, Fe, Co, Ni, Cu, Cr, Ti, Pb, Mo, Mn, etc., used for the urethanization reaction between isocyanate and hydroxyl group. Metal compounds such as simple metals or oxides thereof, halides, carboxylates, phosphates and organometallic compounds are used. Among these, in this thermal decomposition, Fe, Sn, Co, Sb, and Mn are preferably used because they exhibit the effect of making it difficult to generate by-products.

Examples of the Sn metal catalyst include tin oxide, tin chloride, tin bromide, tin iodide, tin formate, tin acetate, tin oxalate, tin octylate, tin stearate, tin oleate, tin phosphate, Examples include dibutyltin chloride, dibutyltin dilaurate, 1,1,3,3-tetrabutyl-1,3-dilauryloxydistanoxane.
Examples of the metal catalyst of Fe, Co, Sb, and Mn include acetates, benzoates, naphthenates, and acetylacetonates.

In addition, the compounding quantity of a catalyst is 0.0001-5 mass% with respect to the reaction liquid as a metal simple substance or its compound, Preferably, it is the range of 0.001-1 mass%.
This thermal decomposition reaction can be carried out either as a batch reaction in which carbamate, a catalyst and an inert solvent are charged in a batch, or a continuous reaction in which carbamate is charged under reduced pressure in an inert solvent containing a catalyst. it can.

  In addition, the same type of alcohol (general formula (7)) as the alcohol used for the production of carbamate (general formula (4)) may be obtained from the separation liquid obtained by the thermal decomposition reaction of carbamate. In such a case, the alcohol (general formula (7)) separated from the decomposition solution obtained by the thermal decomposition reaction of carbamate is preferably separated and recovered as described above, and then preferably in the production of carbamate. Used as a raw material alcohol (the above general formula (4)).

In thermal decomposition, isocyanate and alcohol are produced, and side reactions may produce allophanate, amines, urea, carbonate, carbamate, carbon dioxide, etc. The isocyanate is purified by a known method.
In addition, as isocyanate (the said General formula (6)) obtained by this, the isocyanate (Carbamate (the said Formula (1)) as a decomposition | disassembly object compound manufactured by a manufacturing plant, and the amine (The said Formula (above-mentioned) Depending on the type of 2)), for example, polymethylene polyphenylene isocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), bis (isocyanatomethyl) norbornane (NBDI), 3- isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 4,4'-methylenebis (cyclohexyl _isocyanate) (H 12 MDI), bis (isocyanatomethyl) cyclohexane ( ₆ XDI), hexamethylene diisocyanate (HDI), and the like pentamethylene diisocyanate (PDI).

And in such a method, when an isocyanate and alcohol are removed from the decomposition liquid obtained by the thermal decomposition reaction of carbamate, an isocyanate residue is obtained.
That is, for example, when an isocyanate is produced by reacting an amine, urea and / or N-unsubstituted carbamic acid ester with an alcohol, and thermally decomposing the carbamate, for example, Carbamates and isocyanates, or intermediates thereof may cause undesired polymerization reactions such as multimerization, biuretization, and allophanate formation. In such a case, for example, by-products such as urea derivatives (biuret bodies) and carbamate derivatives (allophanate bodies) are obtained as isocyanate residues. Note that the isocyanate residue may contain, for example, unreacted urea or carbamate.

Such isocyanate residues are usually discarded, but it is required to reduce the amount of waste products from the viewpoint of the global environment and a method for effectively using the recovered isocyanate residues is required. Therefore, in this method, the obtained isocyanate residue is brought into contact with high-pressure high-temperature water in the presence of a solvent to decompose into an amine.
As the solvent, if it is inactive with respect to an isocyanate group or an amino group or has poor reactivity and exhibits hydrolysis resistance (that is, it does not react during hydrolysis of the isocyanate residue), For example, aromatic hydrocarbons may be used.

  Examples of aromatic hydrocarbons include benzene (boiling point: 80 ° C.), toluene (boiling point: 111 ° C.), o-xylene (boiling point: 144 ° C.), m-xylene (boiling point: 139 ° C.), p-xylene ( Boiling point: 138 ° C), ethylbenzene (boiling point: 136 ° C), isopropylbenzene (boiling point: 152 ° C), butylbenzene (boiling point: 185 ° C), cyclohexylbenzene (boiling point: 237-340 ° C), tetralin (boiling point: 208 ° C) , Chlorobenzene (boiling point: 132 ° C.), o-dichlorobenzene (boiling point: 180 ° C.), 1-methylnaphthalene (boiling point: 245 ° C.), 2-methylnaphthalene (boiling point: 241 ° C.), 1-chloronaphthalene (boiling point: 263) ° C.), 2-chloronaphthalene (boiling point: 264-266 ° C.), triphenylmethane (boiling point: 358-359 ° C. (754 m)) Hg)), 1-phenyl-naphthalene (boiling point: 324~325 ℃), 2- phenyl-naphthalene (boiling point: 357 to 358 ° C.), biphenyl (boiling point: 255 ° C.), and the like.

  Such a solvent is also available as a commercial product. For example, barrel process oil B-01 (aromatic hydrocarbons, boiling point: 176 ° C.), barrel process oil B-03 (aromatic hydrocarbons). , Boiling point: 280 ° C), barrel process oil B-04AB (aromatic hydrocarbons, boiling point: 294 ° C), barrel process oil B-05 (aromatic hydrocarbons, boiling point: 302 ° C), barrel process oil B- 27 (aromatic hydrocarbons, boiling point: 380 ° C.), barrel process oil B-28AN (aromatic hydrocarbons, boiling point: 430 ° C.), barrel process oil B-30 (aromatic hydrocarbons, boiling point: 380 ° C.) ), Barrel Therm 200 (aromatic hydrocarbons, boiling point: 382 ° C.), Barrel Therm 300 (aromatic hydrocarbons, boiling point: 344 ° C.), Barrel Therm 400 (aromatic carbonization) Elements, boiling point: 390 ° C., barrel therm 1H (aromatic hydrocarbons, boiling point: 215 ° C.), barrel therm 2H (aromatic hydrocarbons, boiling point: 294 ° C.), barrel therm 350 (aromatic hydrocarbons) , Boiling point: 302 ° C.), barrel therm 470 (aromatic hydrocarbons, boiling point: 310 ° C.), barrel therm PA (aromatic hydrocarbons, boiling point: 176 ° C.), barrel therm 330 (aromatic hydrocarbons, boiling point) : 257 ° C.), Barrel Therm 430 (aromatic hydrocarbons, boiling point: 291 ° C.), (manufactured by Matsumura Oil Co., Ltd.), NeoSK-OIL1400 (aromatic hydrocarbons, boiling point: 391 ° C.), NeoSK-OIL1300 ( Aromatic hydrocarbons, boiling point: 291 ° C.), NeoSK-OIL330 (aromatic hydrocarbons, boiling point: 331 ° C.), NeoSK-OIL170 ( Aromatic hydrocarbons, boiling point: 176 ° C), NeoSK-OIL240 (aromatic hydrocarbons, boiling point: 244 ° C), KSK-OIL260 (aromatic hydrocarbons, boiling point: 266 ° C), KSK-OIL280 (aromatic) Hydrocarbons, boiling point: 303 ° C.) (above, manufactured by Soken Technics).

Such a solvent can be used individually or in combination of 2 or more types.
In addition, the compounding quantity of a solvent is 0.05-9.00 mass parts with respect to 1 mass part of isocyanate residues, Preferably, it is 0.10-5.00 mass parts.
As the solvent in the decomposition of the isocyanate residue, the same solvent as that used in the thermal decomposition of the carbamate is preferably used. In such a case, more preferably, after decomposing the isocyanate residue, the solvent is recovered, and the solvent is used for the thermal decomposition of the carbamate.

If the isocyanate residue is decomposed and the isocyanate residue is decomposed, and then the solvent is recovered and the solvent is used for the thermal decomposition of the carbamate, the cost and workability can be improved.
Moreover, as such a solvent, Preferably, aromatic hydrocarbons whose boiling point is 250 degreeC or more are mentioned.

If an aromatic hydrocarbon having a boiling point of 250 ° C. or higher is used as the solvent, the isocyanate recovery rate can be improved in the thermal decomposition of the carbamate.
The high-pressure high-temperature water is pressurized to a high pressure, that is, 3 to 30 MPa, preferably 6 to 25 MPa, more preferably 6 to 20 MPa, and high temperature, that is, 190 to 350 ° C., preferably 200 to 300 ° C. It is heated water, and is heated and pressurized by a known method.

In addition, the decomposition pressure of an isocyanate residue is 3-30 MPa, Preferably, it is 6-25 MPa, More preferably, it is 6-20 MPa. Moreover, the decomposition temperature of an isocyanate residue is 190-350 degreeC, Preferably, it is 200-300 degreeC.
Moreover, as high-pressure high-temperature water, a hydrolysis ratio (mass ratio of high-pressure high-temperature water / isocyanate residue) is controlled to, for example, 0.5 to 10, preferably 1 to 5.

As a result, the isocyanate residue is hydrolyzed by high-pressure and high-temperature water, and the corresponding amine is produced as a decomposition product, and carbon dioxide and water are by-produced.
At this time, the isocyanate residue to be decomposed is an isocyanate residue obtained by thermally decomposing a carbamate produced by the reaction of an amine, urea and / or N-unsubstituted carbamic acid ester, and an alcohol as described above. In some cases, an amine represented by the following general formula (8) is formed as the corresponding amine.

R ^1- (NH ₂ ) n (8)
(Wherein, ^{R 1} is the same meaning as ^{R 1} in the formula (1), n represents the same meaning as n in formula (1).)
Examples of such amines include polymethylene polyphenylene polyamine (MDA) corresponding to polymethylene polyphenylene isocyanate (MDI), tolylenediamine (TDA) corresponding to tolylene diisocyanate (TDI), and xylylene diisocyanate (XDI). Xylylenediamine (XDA), tetramethylxylylenediamine (TMXDI) corresponding to tetramethylxylylenediisocyanate (TMXDI), bis (aminomethyl) norbornane (NBDI) corresponding to bis (isocyanatomethyl) norbornane (NBDI) NBDA), 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IP) corresponding to 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) A), 4,4'-methylenebis (corresponding to cyclohexyl _{isocyanate) (H} 12 MDI) 4,4'-methylenebis _{(cyclohexylamine)} (H 12 MDA), bis (isocyanatomethyl) cyclohexane _(H 6 XDI) Corresponding bis (aminomethyl) cyclohexane (H ₆ XDA), hexamethylene diamine (HDA) corresponding to hexamethylene diisocyanate (HDI), pentamethylene diamine (PDA) corresponding to pentamethylene diisocyanate, and the like.

  That is, when an isocyanate residue obtained by separating isocyanate and alcohol is decomposed from a decomposition solution obtained by a thermal decomposition reaction of carbamate, the same type of amine (general formula (2)) as used in the production of carbamate and isocyanate (general formula (2) above) is used. Equation (8)) may be obtained. In such a case, the amine obtained by decomposing the isocyanate residue is preferably separated and recovered and then used as a raw material amine (general formula (2)) in the production of the carbamate described above.

As a method for separating the amine, a known method may be used, and distillation is preferable.
Further, in this method, considering economic efficiency, operability, etc., preferably, after the isocyanate residue is decomposed, the solvent is separated and recovered and used for the thermal decomposition of the carbamate. That is, in this method, the carbamate is pyrolyzed in the presence of a solvent recovered after decomposing the isocyanate residue.

In this thermal decomposition reaction, the carbamate obtained above is thermally decomposed, and as described above, an isocyanate corresponding to the amine can be obtained. For example, it is industrially used as a raw material for polyurethane. Polyisocyanate can be easily and efficiently produced.
FIG. 1 is a schematic configuration diagram showing an embodiment of a plant in which the method for treating an isocyanate residue of the present invention is employed.

Hereinafter, an embodiment of a plant when the above-described method for treating an isocyanate residue is industrially implemented will be described with reference to FIG.
In FIG. 1, this plant 1 is an isocyanate production apparatus that employs the above-described method for treating an isocyanate residue for producing an isocyanate residue and obtaining an isocyanate residue by a urea method. 2, a thermal decomposition apparatus 3, and a residue decomposition apparatus 4.

The reactor 2 is equipped in the plant 1 to produce carbamate by reaction of an amine, urea and / or N-unsubstituted carbamic acid ester, and alcohol.
The reaction apparatus 2 includes a reaction tank 5, an amine supply pipe 6 connected to the reaction tank 5, a urea supply pipe 7, and an alcohol supply pipe 8.

The reaction vessel 5 is a carbamation reaction vessel for producing a carbamate by reacting an amine, urea and / or N-unsubstituted carbamic acid ester, and an alcohol, and is capable of controlling temperature and pressure. Consists of heat and pressure resistant container.
Although not shown in such a reaction tank 5, for example, a catalyst supply pipe for supplying a catalyst to the reaction tank 5, and for replacing the inside of the reaction tank 5 with an inert gas (for example, nitrogen gas) if necessary. An inert gas supply pipe, a stirring device for stirring the reaction tank 5 and the like are provided.

The amine supply pipe 6 is an amine supply line for supplying amine to the reaction tank 5, and its downstream end is connected to the reaction tank 5. Moreover, although not shown in figure, the upstream edge part is connected to the amine introduction line in which an amine is introduce | transduced.
The amine supply pipe 6 is connected to the downstream end of an amine reflux pipe 30 (described later) in the middle of the flow direction. Thereby, the amine obtained in the residue decomposition tank 15 (described later) can be refluxed to the amine supply pipe 6 and supplied to the reaction tank 5.

  The urea supply pipe 7 is a urea and / or N-unsubstituted carbamic acid ester supply line for supplying urea and / or N-unsubstituted carbamic acid ester to the reaction tank 5, and its downstream end is It is connected to the reaction vessel 5. Further, the upstream end thereof is connected to a urea and / or N-unsubstituted carbamic acid ester introduction line into which urea and / or N-unsubstituted carbamic acid ester is introduced, though not shown.

The alcohol supply pipe 8 is an alcohol supply line for supplying alcohol to the reaction tank 5, and its downstream end is connected to the reaction tank 5. Moreover, although not shown in figure, the upstream edge part is connected to the alcohol introduction line into which alcohol is introduced.
The alcohol supply pipe 8 is connected to a downstream end of an alcohol reflux pipe 32 (described later) in the middle of the flow direction. Thereby, the alcohol separated in the thermal decomposition tank 10 (described later) can be refluxed to the alcohol supply pipe 8 and supplied to the reaction tank 5.

The thermal decomposition apparatus 3 is installed in the plant 1 to decompose carbamate into isocyanate and alcohol and to separate isocyanate residue from the decomposition liquid.
The thermal decomposition apparatus 3 includes a thermal decomposition tank 10, a carbamate transport pipe 11 connected to the thermal decomposition tank 10, a solvent first supply pipe 12, and an isocyanate discharge pipe 13.

The thermal decomposition tank 10 is a decomposition tank that heats the carbamate obtained in the reactor 2 and decomposes it into isocyanate and alcohol, and is composed of a heat-resistant pressure-resistant container capable of controlling temperature and pressure.
The carbamate transport pipe 11 is a carbamate transport line for transporting the carbamate produced in the reaction apparatus 2 to the pyrolysis tank 10, and its downstream end is connected to the pyrolysis tank 10. Further, the upstream end thereof is connected to the reaction tank 5 in the reaction apparatus 2.

The solvent first supply pipe 12 is a solvent first supply line for supplying a solvent to the thermal decomposition tank 10, and its downstream end is connected to the thermal decomposition tank 10. Further, the upstream end thereof is connected to a solvent first introduction line to which a solvent is introduced, although not shown.
The solvent first supply pipe 12 is connected to a downstream end of a solvent reflux pipe 31 (described later) in the middle of the flow direction. As a result, the solvent used and recovered in the residue decomposition tank 15 (described later) can be refluxed to the solvent first supply pipe 12 and supplied to the thermal decomposition tank 10.

The isocyanate discharge pipe 13 is an isocyanate discharge line for discharging isocyanate obtained by thermal decomposition of carbamate to the outside of the plant 1, and its upstream end is connected to the thermal decomposition tank 10. Moreover, although the downstream edge part is not shown in figure, it is connected to the isocyanate purification line in which isocyanate is refine | purified.
The residue decomposition apparatus 4 is installed in the plant 1 in order to decompose the isocyanate residue obtained in the thermal decomposition apparatus 3 into an amine with high-pressure high-temperature water.

The residue decomposition apparatus 4 includes a residue decomposition tank 15, an isocyanate residue transport pipe 16 connected to the residue decomposition tank 15, a solvent second supply pipe 17, a water supply pipe 18, and a secondary residue discharge pipe 19. .
The residue decomposition tank 15 is a hydrolysis tank for bringing an isocyanate residue and high-pressure high-temperature water into contact with each other to hydrolyze the isocyanate residue into an amine, and is composed of a heat-resistant pressure-resistant vessel capable of controlling temperature and pressure.

Although not shown in the figure, the residue decomposition tank 15 is agitated in a water introduction tube for filling the residue decomposition tank 15 with water (for example, ion-exchanged water) and the residue decomposition tank 15 as necessary. A stirrer or the like is provided.
The isocyanate residue transport pipe 16 is an isocyanate residue transport line for transporting the isocyanate residue separated in the thermal decomposition apparatus 3 to the residue decomposition tank 15, and its downstream end is connected to the residue decomposition tank 15. ing. Further, the upstream end portion is connected to the thermal decomposition tank 10 in the thermal decomposition apparatus 3.

In addition, a residue pressure feed pump (not shown) for pressure transporting the isocyanate residue toward the residue decomposition tank 15 is interposed in the middle of the isocyanate residue transport pipe 16, if necessary. A residue heater (not shown) for heating the isocyanate residue is interposed downstream of (not shown).
The solvent second supply pipe 17 is a solvent second supply line for supplying the solvent to the residue decomposition tank 15, and its downstream end is connected to the residue decomposition tank 15. Further, the upstream end thereof is connected to a solvent second introduction line to which a solvent is introduced, although not shown.

In addition, a solvent pressure pump (not shown) for pressure-transporting the solvent toward the residue decomposition tank 15 is interposed in the middle of the solvent second supply pipe 17, if necessary. Further, if necessary, the solvent pressure pump A solvent heater (not shown) for heating the solvent is interposed downstream of (not shown).
The water supply pipe 18 is a water supply line for supplying high-pressure and high-temperature water to the residue decomposition tank 15, is composed of a heat-resistant pressure-resistant pipe, and its downstream end is connected to the residue decomposition tank 15. Further, the upstream end is connected to a water supply line to which water (not shown) (process recovery water, ion exchange water, etc.) is supplied.

Further, in the middle of the water supply pipe 18, a water pressure pump 21 for pressure-transporting high-pressure high-temperature water toward the residue decomposition tank 15 is interposed. Further, a water heater 20 for heating water is interposed in the middle of the water supply pipe 18 on the downstream side of the water pressure pump 21.
The secondary residue discharge pipe 19 is a secondary residue discharge line for discharging components (secondary residues) remaining without being decomposed into amines or the like when the isocyanate residue is brought into contact with high-pressure high-temperature water. The upstream end portion thereof is connected to the residue decomposition tank 15. Moreover, although the downstream edge part is not shown in figure, it is connected to the secondary residue storage tank in which a secondary residue is stored.

Such a plant 1 further includes an amine reflux pipe 30, a solvent reflux pipe 31, and an alcohol reflux pipe 32.
The amine reflux pipe 30 is an amine reflux line for refluxing the amine obtained by decomposing the isocyanate residue in the residue decomposition apparatus 4 to the amine supply pipe 6 in the reaction apparatus 2, and its upstream end is a residue. While being connected to the decomposition tank 15, the downstream end thereof is connected in the middle of the amine supply pipe 6 in the flow direction.

The solvent reflux pipe 31 is a solvent reflux line for refluxing the isocyanate residue in the residue decomposition apparatus 4 and refluxing the recovered solvent to the solvent first supply pipe 12 in the thermal decomposition apparatus 3. The side end portion is connected to the residue decomposition tank 15, and the downstream end portion thereof is connected midway in the flow direction of the solvent first supply pipe 12.
The alcohol reflux pipe 32 is an alcohol reflux line for refluxing the alcohol obtained by thermally decomposing isocyanate in the thermal decomposition apparatus 3 to the alcohol supply pipe 8 in the reaction apparatus 2, and its upstream end is heated. While being connected to the decomposition tank 10, the downstream end thereof is connected to the middle of the alcohol supply pipe 8 in the flow direction.

Next, a method for producing carbamate and isocyanate by the plant 1 and then decomposing the obtained isocyanate residue will be described.
In this method, first, carbamate is produced in the reactor 2.
In the production of this carbamate, the reaction apparatus 2 is continuously operated, and an amine as a carbamate raw material, urea and / or N-unsubstituted carbamic acid ester, and an alcohol, an amine supply pipe 6, and a urea supply pipe 7. And the pressure supply from the alcohol supply pipe 8 at the above-mentioned ratios and continuously supplied to the reaction tank 5. If necessary, a catalyst is supplied from a catalyst supply pipe (not shown) together with these raw material components.

In this method, in the reaction vessel 5, the amine, urea and / or N-unsubstituted carbamic acid ester, and alcohol react with each other to produce a carbamate.
Further, the carbamate thus obtained is separated in the reaction tank 5, then supplied to the carbamate transport pipe 11, and pressure transported to the thermal decomposition apparatus 3.

Next, in this method, the carbamate is thermally decomposed in the thermal decomposition apparatus 3.
In the thermal decomposition of the carbamate, the thermal decomposition apparatus 3 is continuously operated, and the carbamate supplied from the reaction apparatus 2 (reaction tank 5) via the carbamate transport pipe 11 is heated in the thermal decomposition tank 10 under the above conditions. Pyrolyzed.
Thereby, isocyanate and alcohol are obtained as a decomposition liquid, and an isocyanate residue is obtained by isolate | separating isocyanate and alcohol from a decomposition liquid.

On the other hand, the alcohol obtained in the thermal decomposition tank 10 is separated from the decomposition solution, introduced into the alcohol reflux pipe 32, and refluxed to the alcohol supply pipe 8. Thereby, alcohol is supplied to the reaction tank 5.
And the isocyanate residue obtained in the thermal decomposition tank 10 is supplied to the isocyanate residue transport pipe 16, and is pressure-transported to the residue decomposition apparatus 4.

Next, in this method, the isocyanate residue is decomposed in the residue decomposition apparatus 4.
In the decomposition of the isocyanate residue, the residue decomposition apparatus 4 is continuously operated, and the isocyanate residue supplied from the thermal decomposition apparatus 3 (thermal decomposition tank 10) via the isocyanate residue transport pipe 16 is Decomposed by conditions.
That is, in this method, the residue of the isocyanate residue is increased to a supply pressure of, for example, 3 to 30 MPa through the isocyanate residue transport pipe 16 and heated to a supply temperature of, for example, 190 to 350 ° C. It is supplied to the decomposition tank 15.

In addition, the solvent is increased to a supply pressure of 3 to 30 MPa, for example, via the solvent second supply pipe 17 and heated to a supply temperature of 190 to 350 ° C., for example, in the residue decomposition tank 15. Supplied.
On the other hand, the water flowing into the water supply pipe 18 from the water supply line is pressure-transported in the water supply pipe 18 toward the residue decomposition tank 15 by the water pressure feed pump 21 and, for example, by the water heater 20, for example, Heat to 190-350 ° C. Accordingly, the water is pressurized to 3 to 30 MPa and becomes high-pressure high-temperature water heated to 190 to 350 ° C. and flows into the residue decomposition tank 15.

In the residue decomposition tank 15, for example, the tank temperature (decomposition temperature) is controlled to 190 to 350 ° C., and the tank pressure (decomposition pressure) is 3 to 30 MPa, and a residue pump (not shown) and a water pump By controlling No. 21, the water addition ratio (mass ratio of high-pressure high-temperature water / polyisocyanate residue) is controlled to, for example, 0.5 to 10.
As a result, in the residue decomposition tank 15, the isocyanate residue is hydrolyzed with high-pressure and high-temperature water to produce a corresponding amine as a decomposition product, and secondary residue, carbon dioxide, water, and the like are by-produced.

Although not shown, the decomposition products obtained in the residue decomposition tank 15 are reduced to atmospheric pressure and then separated in a dehydration tower to recover the amine.
The recovered amine is introduced into the amine reflux pipe 30 and refluxed to the amine supply pipe 6. Thereby, the amine is supplied to the reaction vessel 5.
The solvent used in the residue decomposition tank 15 is recovered by a known method, then introduced into the solvent reflux pipe 31 and refluxed to the solvent first supply pipe 12. Thereby, the solvent is supplied to the thermal decomposition tank 10.

The secondary residue obtained in the residue decomposition tank 15 is transported to a secondary residue storage tank (not shown) via the secondary residue discharge pipe 19, and in the secondary residue storage tank (not shown). After being temporarily stored, for example, incineration is performed.
Moreover, such a plant 1 can be equipped with well-known processing apparatuses, such as a distillation apparatus, a filtration apparatus, and a refinement | purification apparatus, in an appropriate position as needed.

And according to such a plant 1, while producing a carbamate and isocyanate continuously, decompose | disassemble an isocyanate residue, the amine obtained by decomposition | disassembly of an isocyanate residue, the solvent used for decomposition | disassembly of an isocyanate residue, Furthermore, The alcohol produced as a by-product in the production of isocyanate can be refluxed and used efficiently.
Although the carbamate treatment method has been described above, the method of the present invention includes known steps such as a pretreatment step such as a dehydration step, an intermediate step, or a post treatment step such as a purification step and a recovery step. You may go out.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to an Example at all.
<Definition of 2,4-tolylenediamine recovery (mol%)>
The recovery rate (mol%) of 2,4-diaminotoluene (hereinafter 2,4-TDA) was such that all of the insoluble components of the filter residue introduced into the reactor were 2,4-bis (butoxycarbonylamino) toluene (hereinafter 2). , 4-TDC), and the ratio of 2,4-TDA (mol) actually obtained to the theoretical recovery amount (mol) when all of this is recovered as 2,4-TDA. .
<Preparation of isocyanate residue (compound containing urea and / or carbamate and derivatives thereof)>
(Preparation Example 1)
(1) Carbamate reaction A 1-L SUS autoclave equipped with a pressure control valve, a reflux condenser, a gas-liquid separator, and a stirrer was charged with 2,4-TDA (76.5 g: 0.626 mol), urea ( 113 g: 1.87 mol) and 1-butanol (255 g: 3.44 mol) were charged. Further, zinc p-toluenesulfonate (0.64 g: 1.57 mmol) as a catalyst and 1-butanol (23. 4 g: 316 mmol), and the internal pressure was adjusted with a pressure control valve so as to keep the reaction temperature at 215 ° C. while stirring at 500 rpm while flowing 1 L of nitrogen gas per minute, and the mixture was reacted for 4 hours.

When a part of the reaction solution was collected and quantified, it was confirmed that 2,4-bis (butoxycarbonylamino) toluene was produced in a yield of 86.4 mol% with respect to 2,4-diaminotoluene. It was done. It was also confirmed that mono (butoxycarbonylamino) aminotoluene was produced in a yield of 3.2 mol%.
(2) Distillation of light-boiling components under reduced pressure 375 g of the reaction solution obtained by the carbamate reaction was charged into a 500 mL glass four-necked flask equipped with a stirrer and a cooling tube, and vacuumed while stirring at 230 rpm. The inside of the container was depressurized to 2 kPa with a pump. While circulating 25 ° C. circulating water through the cooling pipe, the inside of the container was heated to 100 ° C. and concentrated. Thereafter, the circulating water temperature was set to 80 ° C., and the inside of the container was heated to 180 ° C. and concentrated to obtain 193 g of a brown concentrate.
(3) Thermal decomposition of carbamate and separation and recovery of isocyanate residue In a 500 mL glass four-necked flask equipped with a stirrer and a rectifying column with a reflux tube at the top, reduced pressure distillation of the above light boiling content 72 g of the concentrated solution obtained in the last and 140 g of Barrel Process Oil B-05 (manufactured by Matsumura Oil Co., Ltd.) as the solvent were charged, respectively, and the circulating water temperature in the reflux tube was set to 90 ° C. and stirred at 230 rpm. The inside was depressurized to 100 hPa.

Subsequently, the temperature control setting of the reactor internal thermometer was set to 250 ° C. and the temperature was raised to raise the tower top temperature. At this time, after confirming that tolylene diisocyanate (hereinafter referred to as TDI) began to condense in the reflux tube, the reflux liquid was distilled by setting the reflux ratio to 5 (= reflux 10 seconds / distillation 2 seconds).
After confirming that distillation was stopped after 1 hour and the rectifying tower TOP temperature was lowered, heating was stopped, and the reaction solution was filtered with 5A filter paper to separate the filtrate and the filter residue.

Then, the filter residue was recovered by washing with acetone and drying together with the solid matter adhering to the wall of the reaction vessel to obtain 7.0 g of a yellowish brown filter residue acetone insoluble matter.
<Hydrolysis of isocyanate residue (carbamate pyrolysis residue)>
Example 1
A 36 mL SUS autoclave equipped with a thermocouple and a pressure regulating valve was charged with 3.0 g of the filter residue acetone-insoluble matter obtained in Production Example 1 and 5.8 g of barrel process oil B-05. The interior was filled with ion exchange water. The reactor was placed in an electric furnace and reacted for 20 minutes while adjusting with a pressure regulating valve so as to maintain a reaction temperature of 280 ° C. and an internal pressure of 20 MPa. The water addition ratio (mass ratio of ion-exchanged water (high pressure / high temperature water) / filtered residue acetone insoluble matter (isocyanate residue)) at this time was set to 9.

After the reactor was allowed to cool to room temperature, no solid matter remained in the recovered reaction solution, and it was confirmed that all of the filter residue had been decomposed. A part of the reaction solution was collected and quantified with a liquid chromatograph (UV detector (254 nm) and RI detector), and it was found that the recovery rate of 2,4-TDA was 83.5 mol%. It was.
(Example 2)
The decomposition reaction of the carbamate thermal decomposition residue was performed in the same manner as in Example 1 except that the reaction temperature was 190 ° C.

After the reactor was allowed to cool to room temperature, no solid matter remained in the recovered reaction solution, and as a result of HPLC measurement of the reaction solution, the recovery rate of 2,4-TDA was 33.9 mol%. I understood it.
(Comparative Example 1)
Into a 36 mL SUS autoclave equipped with a thermocouple and pressure control valve, 3.0 g of the acetone residue insoluble in the filter residue obtained in Production Example 1 was charged, and the barrel process oil B-05 was not charged. The interior was filled with ion exchange water. As a result, the acetone residue insoluble in the filter surfaced on the liquid surface without repelling water at all. In this state, the reactor was put into an electric furnace, the pressure was maintained at 20 MPa by a pressure regulating valve, and the reaction was caused because a line blockage was observed while the reactor was heated to 260 ° C. Interrupted.
<Confirmation of hydrolysis resistance of barrel process oil B-05>
(Reference Example 1)
It was confirmed by the following operation that the solvent used in the thermal decomposition of Production Example 1 did not react under the hydrolysis conditions of the isocyanate residue obtained by thermal decomposition.

  7.3 g of barrel process oil B-05 was charged into the same reactor as in Example 1, and the system was filled with ion-exchanged water. The reactor was placed in an electric furnace, heated to 320 ° C. and held for 20 minutes, and heating was stopped. The pressure during the reaction was maintained at 20 MPa by a pressure regulating valve. After the reactor was allowed to cool to room temperature, the collected reaction liquid was subjected to gas chromatographic measurement. As a result, no significant difference was confirmed as compared with the standard product, and no peak considered to be a decomposition product was detected.

DESCRIPTION OF SYMBOLS 1 Plant 2 Reaction apparatus 3 Thermal decomposition apparatus 4 Residue decomposition apparatus 5 Reaction tank 6 Amine supply pipe 7 Urea supply pipe 8 Alcohol supply pipe 10 Thermal decomposition tank 11 Carbamate transport pipe 12 Solvent first supply pipe 13 Isocyanate discharge pipe 15 Residue decomposition tank 16 Isocyanate residue transport pipe 17 Solvent second supply pipe 18 Water supply pipe 19 Secondary residue discharge pipe 20 Water heater 21 Pressure pump 30 Amine reflux pipe 31 Solvent reflux pipe 32 Alcohol reflux pipe

Claims (3)

An isocyanate residue obtained by separating isocyanate and alcohol from a decomposition liquid obtained by a thermal decomposition reaction of carbamate is 3-30 MPa and 190-350 ° C. in the presence of a solvent consisting of aromatic hydrocarbons having a boiling point of 250 ° C. or higher . Contact with high pressure and high temperature water to decompose to amine ,
Furthermore, after decomposing the isocyanate residue, the solvent is recovered,
A method for treating an isocyanate residue, characterized in that the carbamate is thermally decomposed in the presence of a solvent recovered after the isocyanate residue is decomposed . The carbamate
The method for treating an isocyanate residue according to claim 1, wherein the isocyanate residue is a carbamate produced by a reaction of an amine, urea and / or an N-unsubstituted carbamic acid ester and an alcohol. The amine used for the production of carbamate is an amine obtained by decomposing isocyanate residue,
The method for treating an isocyanate residue according to claim 2 , wherein the alcohol used for producing the carbamate is an alcohol separated from a decomposition solution obtained by a thermal decomposition reaction of carbamate.

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