JP2915784B2 - Purification method of aliphatic isocyanate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an aliphatic isocyanate, and more particularly, to a method for purifying an aliphatic isocyanate capable of reducing hydrolyzable chlorine and coloring substances contained in the aliphatic isocyanate. About the method.

[0002]

BACKGROUND OF THE INVENTION A process for obtaining an aliphatic isocyanate by reacting an aliphatic amine and / or its hydrochloride or carbonate with phosgene in an inert solvent is known.
It is widely practiced industrially. The aliphatic isocyanate produced by this method contains impurities containing hydrolyzable chlorine and impurities that are colored by heating (hereinafter referred to as “color-causing substances”). Since it is difficult to sufficiently remove these impurities by ordinary distillation, there is a problem when synthesizing a derivative such as a urethane prepolymer or a diisocyanate trimer. For example, hydrolyzable chlorine significantly inhibits the polyurethane production reaction and reduces the performance of the resulting polyurethane. On the other hand, the coloring substance causes the polyurethane as a product to be colored, thereby significantly reducing its commercial value.

In order to solve these problems, various methods have been conventionally proposed. As a method for reducing hydrolyzable chlorine in an organic isocyanate, for example, a method in which a metal, a metal oxide, an organic acid salt or an alkali metal carbonate is added to an organic isocyanate and heat-treated (Japanese Patent Publication No. 41-7 / 1971)
No. 858, JP-B-42-17887, JP-B-42-1
9450, JP-A-53-119823, etc.) and a method of adding a formic acid derivative such as formic acid or formamide to an organic isocyanate and heating (Japanese Patent Publication No. 51-102).
JP-A-42-4), a method of treating an organic isocyanate with a metal hydride of Groups I, II and III and distilling the same.
137), a method in which phosphoric acid or sulfuric acid is added to an organic isocyanate for distillation (Japanese Patent Publication No. 45-21801), a method in which an organic isocyanate is contacted with an inert gas (Japanese Patent Publication No. 46-29841, Showa 48-768
No. 39) has been proposed.

As a method for preventing coloring of polyurethane using an organic isocyanate, a method of adding various antioxidants to polyurethane (for example, Japanese Patent Publication No. Sho 44-3330).
And Japanese Patent Publication No. Sho 61-49300), and a method of heat treatment after detarring (Japanese Patent Application Laid-Open No. 58-22206).

[0005] Further, as a method of reducing hydrolyzable chlorine in the organic isocyanate and preventing coloring of the polyurethane, a method of distilling the organic isocyanate by adding iron hydroxide to the organic isocyanate during the purification of the organic isocyanate (particularly, Kosho 42
No. 26767) and a method of treating with an epoxy compound (US Pat. No. 3,793,362).

However, of these methods, the method using an additive has a problem that it is necessary to separate and recover the used additive after purifying the isocyanate. However, there has been a problem that a sufficient effect cannot always be obtained with respect to the aliphatic isocyanate.

By the way, conventionally, when an organic isocyanate is exposed to a high temperature for a long time, an undesired reaction such as polymerization occurs and the yield of the isocyanate is reduced. It has generally been thought that it is necessary to perform at a low temperature in a short time.

However, according to an experiment conducted by the present inventors, surprisingly, even when the solvent is distilled off from an inert solvent solution of aliphatic isocyanate for a long time, the yield of aliphatic isocyanate is increased. If a specific amount of the inert organic solvent in the inert organic solvent solution containing the aliphatic isocyanate is distilled off at a specific temperature for a specific time for a specific period of time, a colorless, transparent, hydrolyzable The inventors have found that an aliphatic isocyanate having a significantly reduced chlorine content can be obtained, and have completed the present invention.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art as described above, and it is intended to significantly reduce hydrolyzable chlorine and coloring substances contained in aliphatic isocyanates. It is an object of the present invention to provide a method for purifying an aliphatic isocyanate.

[0010]

SUMMARY OF THE INVENTION A first method for purifying an aliphatic isocyanate according to the present invention comprises the steps of:
Fat contained in an amount of 3 to 25% by weight in terms of aliphatic amine
Solution of an aromatic amine or its hydrochloride in an inert organic solvent (a)
Prepare and prepare the aliphatic amine or its hydrochloride in the solution (a)
Containing hydrolyzable chlorine
Crude aliphatic isocyanate solution in inert organic solvent (b)
Under a pressure condition of 200 to 760 mmHg,
By heating to a temperature of 270 ° C., the solution (b)
The method is characterized in that the solvent in an amount equal to or more than the weight of the aliphatic isocyanate in (b) is distilled off over 2 hours or more.

In a preferred embodiment of the present invention, an aliphatic
The amine or its hydrochloride is converted to an aliphatic amine by 3 to 2
Aliphatic amines or hydrochloric acid thereof in an amount of 5% by weight
Prepare an inert organic solvent solution (a) of a salt, and prepare a solution of the fat in the solution (a).
Do not react aliphatic amines or their hydrochlorides with phosgene.
, Crude aliphatic isocyanate containing hydrolyzable chlorine
In an inert organic solvent solution (b) of 200 to 760 mmHg
Under the pressure conditions of above, heated to a temperature of 140-270 ° C.,
From the solution (b) , the solvent in an amount equal to or more than the weight of the aliphatic isocyanate in the solution (b) is distilled off over 2 hours or more, and then the obtained aliphatic isocyanate-containing material is removed. It is desirable to obtain an aliphatic isocyanate by distillation.

Further, in a preferred embodiment of the present invention,
For example, when the inert organic solvent is o-dichlorobenzene, the crude aliphatic isocyanate containing the hydrolyzable chlorine is used.
It is desirable to heat the solution of the inert organic solvent (b) (b) at a temperature of 150 to 185 ° C. for 3 to 6 hours to distill off the inert organic solvent in the solution.

The aliphatic isocyanate according to the present invention,
Purification method is to a crude aliphatic isocyanate containing hydrolyzable chlorine , the weight of the isocyanate is equal to or more than
While adding the amount of the inert organic solvent all at once or gradually, the solution of the obtained crude aliphatic isocyanate containing hydrolyzable chlorine in an inert organic solvent is 200 to 760 m
By heating at a temperature of 140 to 270 ° C. under a pressure condition of mHg, an amount of the inert organic solvent equal to or more than the weight of the aliphatic isocyanate in the inert organic solvent solution over 2 hours or more is obtained. Is gradually distilled off.

In a preferred embodiment of the present invention, the crude aliphatic isocyanates which contain hydrolyzable chlorine, the iso
At once inert organic solvent weight and the weight or amount of cyanate, or gradually adding an inert organic solvent solution of the crude aliphatic isocyanates that contain obtained hydrolyzable chlorine, 200 ~ 760mmHg pressure condition
By heating at a temperature of 140 to 270 ° C.
Weight and the weight more than the amount of aliphatic isocyanates of the inert organic solvent solution over time, the inert organic solvent gradually evaporated, then fat from the resulting aliphatic isocyanate-containing compound It is desirable to obtain the aromatic isocyanate by distillation.

In a further preferred embodiment of the present invention,
For example, when the inert organic solvent is o-dichlorobenzene, the above solution of the crude aliphatic isocyanate in an inert organic solvent is heated at a temperature of 150 to 185 ° C.
Preferably, the inert organic solvent is distilled off over a period of up to 6 hours.

According to the first or second method for purifying an aliphatic isocyanate according to the present invention, the content of hydrolyzable chlorine and coloring substances in the aliphatic isocyanate can be remarkably reduced. Moreover, this purification method
It can be easily implemented industrially. When the aliphatic isocyanate thus obtained is subjected to, for example, a urethane reaction, an uncolored polyurethane is obtained.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for purifying an aliphatic isocyanate according to the present invention will be specifically described. First Method for Purifying Aliphatic Isocyanate [Inert Organic Solvent Solution] In the first method for purifying aliphatic isocyanate according to the present invention, crude aliphatic isocyanate containing hydrolyzable chlorine and an inert organic solvent are used. A solution comprising a solvent (an inert organic solvent solution) is used. This solution comprising a crude aliphatic isocyanate containing hydrolyzable chlorine and an inert organic solvent is obtained, for example, by reacting an aliphatic amine or its hydrochloride with phosgene in an inert organic solvent. More specifically, this inert organic solvent solution is (i) a two-step cooling / heating method in which an aliphatic amine and phosgene are first reacted at a low temperature in an inert organic solvent, and then phosgene is further supplied at a high temperature. Or (ii) a hydrochloride method in which an aliphatic amine is first reacted with hydrogen chloride gas to form an aliphatic amine hydrochloride in an inert organic solvent, and then the aliphatic amine hydrochloride is reacted with phosgene under heating. Or (iii) in an inert organic solvent, an aliphatic amine is reacted with carbon dioxide to form a carbamate, and phosgene is first reacted at a low temperature and then at a high temperature. It is also manufactured by In the present invention, the hydrochloride method (ii) is particularly preferred.

Hereinafter, the hydrochloride method (ii) will be described in detail. The reaction between the hydrochloride of an aliphatic amine and phosgene can be performed until the conversion of the hydrochloride to an aliphatic isocyanate becomes 99% or more. desirable. When the conversion is low, not only the yield of the aliphatic isocyanate becomes low, but also the removal of the hydrolyzable chlorine becomes insufficient.

The reaction temperature varies depending on the kind of the starting amine and the reaction method, but is usually from 80 to 180 ° C. After the reaction of the aliphatic amine or its hydrochloride with phosgene as described above, the solution of the aliphatic isocyanate obtained in an inert organic solvent is heated to drive off the dissolved phosgene and HCl. In addition, at the time of this heating, nitrogen gas may or may not flow, but it is preferable to flow nitrogen gas.

The hydrolyzable chlorine is a by-product of the reaction between the organic amine and phosgene, and is, for example, a primary carbamoyl chloride (1) represented by the following formula (1) or a secondary carbamoyl chloride (1) represented by the following formula (2): Present in the form of carbamoyl chloride (2). In the formula, R represents a hydrocarbon group.

[0021]

Embedded image

Aliphatic isocyanate means that an NCO group is bonded to a carbon atom such as a hydrocarbon group, and the carbon atom bonded to the NCO group does not constitute a part of an aromatic ring such as a benzene ring. Say things. Therefore, the aliphatic isocyanate includes a compound having an aromatic ring such as a benzene ring in the molecule, even if the NCO group is not directly bonded to the aromatic ring.

Specific examples of such aliphatic isocyanates include, for example, n-amyl isocyanate,
Hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), m-xylylene diisocyanate, lysine ethyl ester triisocyanate, and the like.

The inert organic solvent refers to an organic solvent which is non-reactive or hardly reactive with both isocyanate and phosgene. Specific examples of such an inert organic solvent include toluene, xylene and the like. , Mesitylene,
In addition to alkylated aromatic hydrocarbons such as diethylbenzene, halogenated aromatic hydrocarbons such as monochlorobenzene and o-dichlorobenzene, alicyclic hydrocarbons such as decahydronaphthalene (decalin), sulfolane, isobutyl n-butyrate, etc. Is mentioned. Among these inert organic solvents, halogenated aromatic hydrocarbons are preferably used.
This inert organic solvent is usually used in an amount such that the concentration of the starting amine is 3 to 25% by weight when preparing the inert organic solvent solution. In other words, in a total of 100% by weight of an aliphatic amine such as isophoronediamine and hexamethylenediamine and an inert organic solvent such as o-dichlorobenzene, the amount of the inert organic solvent is 75 to 97% by weight. Used in such amounts. [Purification of Aliphatic Isocyanate] In the first method for purifying the aliphatic isocyanate according to the present invention, the crude aliphatic isocyanate containing hydrolyzable chlorine obtained as described above and an inert organic Heating the solution comprising the solvent (inert organic solvent solution) at a temperature of 140 to 270 ° C., which is lower than the boiling point of the aliphatic isocyanate to be purified,
The inert organic solvent is distilled off over 2 hours or more, preferably 3 to 6 hours. The heating of the inert organic solvent solution depends on the type of the inert organic solvent to be added,
Usually, it is carried out under a pressure condition of about 200 to 760 mmHg. In the present invention, it is preferable to heat the inert organic solvent solution under the above-mentioned temperature and pressure conditions to distill the inert organic solvent such as o-dichlorobenzene at an average distillation rate.

For example, the aliphatic isocyanate is isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI), and the inert organic solvent used is o.
In the case of -dichlorobenzene, the inert organic solvent solution is heated at a temperature of 140 to 270 ° C., preferably 150 to 185 ° C., for 2 hours or more, preferably 3 to 6 hours.
Usually, o-dichlorobenzene as an inert organic solvent may be distilled off under a pressure condition of about 400 to 600 mmHg over time.

In the present invention, the inert organic solvent solution is heated under the above-mentioned conditions to separate the inert organic solvent solution from the inert organic solvent solution by the same weight or more as the weight of the aliphatic isocyanate in the inert solvent solution. By distilling the solvent, preferably 5 to 15 times by weight, a purified aliphatic isocyanate can be obtained.

When an inert organic solvent or the like remains in the obtained aliphatic isocyanate, the inert organic solvent or the like is then removed from the obtained aliphatic isocyanate-containing substance (A). Further distillation yields the desired aliphatic isocyanate. This distillation operation is usually carried out in the range of 2 to 1
Under a reduced pressure condition of about 0 mmHg, at a temperature of about 100 to 200 ° C., from the aliphatic isocyanate-containing material (A), first, an inert organic solvent and low-boiling impurities remaining in the content are distilled off, Then, the desired aliphatic isocyanate is distilled off. If the above-mentioned inert organic solvent or the like is not already contained in the aliphatic isocyanate-containing substance (A), this distillation operation may be omitted.

The aliphatic isocyanate thus obtained has a purity of usually about 99 to 99.9% by weight, and the content of hydrolyzable chlorine measured according to JIS K 1556 is: Usually, it is remarkably low at about 20 to 50 ppm, and its coloring degree is excellent at Hazen number of 10 or less.

Second Method for Purifying Aliphatic Isocyanate In the second method for purifying aliphatic isocyanate according to the present invention, an inert organic solvent is once added to crude aliphatic isocyanate containing hydrolyzable chlorine. To the resulting organic solvent solution of crude aliphatic isocyanate containing hydrolyzable chlorine at a temperature of 140 to 270 ° C. while adding the solution slowly or gradually. The inert organic solvent in an amount equal to or greater than the weight of the aliphatic isocyanate in the active organic solvent solution is gradually distilled off,
An aliphatic isocyanate is obtained.

In a preferred embodiment of the present invention, the crude organic isocyanate containing hydrolyzable chlorine is added at a time with the same weight or more, preferably 3 to 15 times by weight of the above-mentioned inert organic solvent as the weight of the isocyanate. Preferably, while gradually adding, the resulting solution of the crude aliphatic isocyanate containing hydrolyzable chlorine in an inert organic solvent at a temperature lower than the boiling point of the aliphatic isocyanate to be purified is from 140 to 27.
By continuing to heat to a temperature of 0 ° C., the inert organic solvent added in an amount equal to or greater than the weight of the aliphatic isocyanate in the inert organic solvent solution over 2 hours, preferably 3 to 6 hours. It is desirable to distill off the solvent gradually. The heating of such a crude aliphatic isocyanate containing hydrolyzable chlorine is usually performed under a pressure condition of about 200 to 760 mmHg, depending on the type of the inert organic solvent added. Thus, in the present invention, the inert organic solvent solution is heated under the above-described temperature and pressure conditions, and the inert organic solvent such as o-dichlorobenzene can be distilled at an average distillation rate. preferable.

In the present invention, a required amount (total amount) of an inert organic solvent is added to the crude aliphatic isocyanate containing hydrolyzable chlorine at a time, that is, under the above-mentioned conditions. The inert organic solvent in the solvent solution may be distilled off, but the inert organic solvent is gradually added to the crude aliphatic isocyanate at the same rate as the inert organic solvent at the same time as the inert organic solvent is added. Preferably, the inert organic solvent in the solution is distilled off.

For example, when the aliphatic isocyanate is isophorone diisocyanate (IPDI) and the inert organic solvent used is o-dichlorobenzene, the crude aliphatic isocyanate containing hydrolyzable chlorine is added to the system. The temperature of 14
While heating and holding at a temperature of 0 to 270 ° C, preferably 150 to 185 ° C, the inert organic solvent is gradually added over 2 hours or more, preferably 3 to 6 hours, and the obtained crude aliphatic isocyanate is obtained. The inert organic solvent may be gradually distilled off from the inert organic solvent solution over the above temperature and time. In addition, the addition / distillation operation of such an inert organic solvent is usually 400 to 6
It is performed under a pressure condition of about 00 mmHg.

In the present invention, after the addition and distillation of the inert organic solvent to the crude aliphatic isocyanate as described above, the resulting aliphatic isocyanate-containing material is obtained.
The aliphatic isocyanate is obtained by distillation from (B). This distillation operation is usually performed under reduced pressure conditions of about 2 to 10 mmHg.
At a temperature of about 00 to 200 ° C., first, an inert organic solvent and low boiling impurities remaining in the aliphatic isocyanate-containing substance (B) are distilled off from the aliphatic isocyanate-containing substance (B), and then the desired aliphatic isocyanate is removed. It is performed by distilling.
When the above-mentioned aliphatic organic isocyanate-containing substance (B) does not contain the above-mentioned inert organic solvent or the like, this distillation operation may be omitted.

The aliphatic isocyanate thus obtained has a remarkably low content of hydrolyzable chlorine and a low degree of coloring. Such a second aspect of the present invention
May be applied to the aliphatic isocyanate obtained by the first purification method according to the present invention. Further, it can be applied to the purification of colored non-standard crude aliphatic isocyanates containing a large amount of hydrolyzable chlorine.

[0035]

According to the present invention, the amount of hydrolyzable chlorine contained in the aliphatic isocyanate and acting as an inhibitor of the reaction for producing polyurethane and deteriorating the quality of the produced polyurethane can be greatly reduced. The amount of the coloring substance can also be reduced. Therefore, when the thus-purified aliphatic isocyanate is used as a raw material, resins such as urethane, isocyanurate, and urea can be synthesized with good reactivity, and the quality of these obtained resin products is also improved. be able to.

[0036]

Now, the present invention will be described in further detail with reference to Examples. The purpose of the present invention is to make it easier to understand the contents of the present invention. It is not something to be done.

[0037]

[Reference Example 1] 300 equipped with a jacket, a stirrer, a gas blowing pipe, and a condenser, and the inner wall of which is glass-lined.
Using a liter reactor, the trans / cis ratio = 2
Mixed liquid 2 composed of 8/72 isophoronediamine 6% (% by weight; the same applies hereinafter) and o-dichlorobenzene 94%
00 liters was maintained at 150 ° C. and dry hydrogen chloride gas was blown into the mixture to convert all amines to hydrochlorides. While maintaining the obtained slurry at the same temperature (150 ° C.), phosgene was blown into the slurry at a rate of 33 kg / hour. Four hours after the start of phosgene blowing, the solution became clear. Analysis of the transparent liquid by gas chromatography revealed that the conversion of the amine was 99.7%. Degassing was performed by blowing nitrogen gas into the transparent liquid under a slight reduced pressure to obtain 230 kg of an isophorone diisocyanate (IPDI) -containing liquid [IPDI content: 18 kg]. The content of hydrolyzable chlorine in the isophorone diisocyanate (IPDI) -containing liquid was measured by the method described in JIS K1556 and found to be 423 ppm. The solution was strongly colored brown.

[0038]

REFERENCE EXAMPLE 2 Using the same apparatus as in Reference Example 1, 200 liters of a mixed liquid containing 6% of hexamethylenediamine and 94% of o-dichlorobenzene was kept at 100 ° C., and dry hydrogen chloride gas was added to the mixed liquid. Blowing changed all amines to hydrochloride. While keeping the obtained slurry at 160 ° C,
Phosgene was blown into the slurry at a rate of 28 kg / hour. 8.5 hours after the start of phosgene blowing, the solution became clear. Analysis of the transparent liquid by gas chromatography revealed that the conversion of the amine was 99.5%.
Met. Degassing is performed by blowing nitrogen gas into the transparent liquid under slightly reduced pressure, and hexamethylene diisocyanate (HD
I) 240 kg of the containing liquid [HDI content: 20 kg] was obtained.
When the content of hydrolyzable chlorine in this hexamethylene diisocyanate (HDI) -containing liquid was measured, it was 373.
ppm. The solution was strongly colored brown.

[0039]

[Reference Example 3] Using the same apparatus as in Reference Example 1, trans
8.5% isophoronediamine with a / cis ratio of 28/72
(Weight%; the same applies hereinafter) and 91.5% of decahydronaphthalene (decalin) in 200 liters of a mixed solution.
Maintained at 50 ° C., dry hydrogen chloride gas was blown into the mixture to convert all amines to hydrochlorides. While maintaining the obtained slurry at the same temperature (150 ° C.), phosgene was blown into the slurry at a rate of 33 kg / hour. Five hours after the start of phosgene blowing, the solution became clear. When the transparent liquid was analyzed by gas chromatography, the conversion of the amine was 99.5%. Degassing was performed by blowing nitrogen gas into the transparent liquid under a slight reduced pressure, to obtain 150 kg of a liquid containing isophorone diisocyanate (IPDI). When the content of hydrolyzable chlorine in the isophorone diisocyanate (IPDI) -containing liquid was measured, it was found to be 59.
It was 1 ppm. The solution was strongly colored brown.

[0040]

Example 1 A distillation apparatus having a 2 liter flask heated by a mantle heater as a reboiler and a distillation column equipped with a 35 mm diameter, five-stage Oldershaw-type vacuum jacketed distillation column as a distillation column was obtained in Reference Example 1. IPD
Charge 2 kg of I-containing liquid and raise the temperature inside the reboiler to 175 to 1
The temperature was maintained at 85 ° C and the pressure was increased to 560 to 400-400 g so that the amount of o-dichlorobenzene distilled per hour was 350-400 g.
Adjust the pressure to 600 mmHg and adjust the voltage applied to the mantle heater over 3 hours to remove
1.1 kg of dichlorobenzene were distilled off.

A distillation operation (distillation temperature: 127 ° C.) was added to 0.9 kg of the IPDI-containing liquid remaining in the distillation apparatus under a reduced pressure of 2 mmHg using a small distillation apparatus different from the above-mentioned distillation apparatus to give a purity of 99%. 0.9% and colorless and transparent (the degree of coloring is represented by Hazen number: 10 or less; the same applies hereinafter) IPDI distillate 10
1 g was obtained. When the content of hydrolyzable chlorine in the IPDI distillate was measured by the method described in JIS K1556, 3
It was 6 ppm.

[0042]

[Comparative Example 1] In Example 1, o-
The same operation as in Example 1 was carried out except that 1.1 kg of dichlorobenzene was distilled under reduced pressure of 2 mmHg over 1 hour, and the purity was 99.9% and the degree of coloration expressed by Hazen number was 15 to 20. 99g of IPDI distillate (purified IPDI)
I got The content of hydrolyzable chlorine in this IPDI distillate was 133 ppm.

[0043]

Example 2 Using the same distillation apparatus as in Example 1, Reference Example 2
Hexamethylene diisocyanate (HDI) obtained by
2 kg of the liquid solution was treated as follows.

First, the reboiler temperature is set to 150 to 160 ° C.
At a pressure of 260 to 290 so that the amount of o-dichlorobenzene distilled out per hour is 250 to 300 g.
1.1 kg of o-dichlorobenzene was distilled from the HDI-containing liquid over 4 hours while adjusting the pressure to mmHg and the voltage applied to the mantle heater.

To 0.9 kg of the liquid remaining in the distillation apparatus,
Using a distillation apparatus different from the above distillation apparatus, a distillation operation was performed under reduced pressure of 2 to 3 mmHg to obtain 118 g of a colorless and transparent HDI distillate having a purity of 99.9%. The content of hydrolyzable chlorine in the HDI distillate was 31 ppm.

[0046]

Comparative Example 2 In Example 2, the reboiler temperature was set to 11
The temperature is maintained at 5 to 125 ° C., and the pressure is adjusted to 1 to bring the amount of o-dichlorobenzene distilled out per hour to 250 to 300 g.
Example 2 was carried out in the same manner as in Example 2 except that 1.1 kg of o-dichlorobenzene was distilled from the HDI-containing solution over 4 hours while adjusting the pressure to 20 to 140 mmHg and adjusting the voltage applied to the mantle heater.

As a result, 119 g of a colorless and transparent HDI distillate having a purity of 99.9% was obtained. The content of hydrolyzable chlorine in the HDI distillate was 80 ppm.

[0048]

Example 3 The reboiler of the Oldershaw distillation apparatus used in Example 1 was charged with 1000 g of crude isophorone diisocyanate (crude IPDI) containing 120 ppm of hydrolyzable chlorine and having a degree of coloration of 20 as represented by the Hazen number. 400
Under a pressure of ４430 mmHg, the reboiler temperature was maintained at 160 ° C., and the same amount of o-dichlorobenzene was simultaneously distilled off while adding o-dichlorobenzene at a rate of 250 g per hour.

After 4 hours, the addition and distillation of o-dichlorobenzene were stopped, and IPDI was distilled under reduced pressure of 3 mmHg (distillation temperature: 134 ° C.). Since 82 g of the first fraction contained o-dichlorobenzene, the fraction
When the hydrolyzable chlorine in 51 g was measured, it was 24 ppm.
And the coloring degree was 10 or less in Hazen number.

[0050]

Comparative Example 3 1000 g of the same crude isophorone diisocyanate (IPDI) in the same apparatus as in Example 3
And IPDI was distilled under reduced pressure of 3 mmHg (distillation temperature: 134 ° C.). Discard 85 g of first distillate and 748 for next distillate
When the hydrolyzable chlorine in g was measured, it was 103 ppm, and the coloring degree was between 10 and 15 in Hazen number.

[0051]

Examples 4 to 7 The procedure of Example 1 was repeated, except that the temperature in the reboiler was kept at 150 to 160 ° C. and the time for distilling off o-dichlorobenzene was changed as shown in Table 1. Purification of isocyanate (IPDI) was performed.

Table 1 shows the results.

[0053]

[Table 1]

[0054]

Example 8 1.35 kg of the IPDI-containing liquid obtained in Reference Example 3 (IPDI in the liquid) was placed in the same distillation apparatus as in Example 1.
Content: 143 g), and the temperature in the reboiler is adjusted to 17
0 to 175 ° C, and the pressure is set to 400 to 45 so that the amount of decalin distilled per hour becomes 200 to 250 g.
Over 4 hours, 930 g of decalin was distilled from the IPDI-containing liquid while adjusting the pressure to 0 mmHg and the voltage applied to the mantle heater.

The IPDI-containing liquid 4 remaining in the distillation apparatus
A distillation operation (distillation temperature: 127 ° C.) was applied to 00 g under a reduced pressure of 2 mmHg using a small distillation apparatus different from the above distillation apparatus, and 97 g of a colorless and transparent IPDI distillate having a purity of 99.9% was obtained.
I got When the content of hydrolyzable chlorine in the IPDI distillate was measured by the method described in JIS K1556, it was 29 ppm.
Met.

[0056]

Comparative Example 4 In Example 1, o-
The pressure was adjusted to 560 to 570 mmHg so that the amount of dichlorobenzene distilled per hour was about 40 g, and the voltage applied to the mantle heater was adjusted for 4 hours to remove o-dichlorobenzene from the IPDI-containing solution. To 17
The same operation as in Example 1 was carried out except that 0 g was distilled off, and the purity was 99.9% and the coloring degree expressed by the Hazen number was 10%.
96 g of an IPDI distillate (purified IPDI) of ＤＩ20 was obtained. The content of hydrolyzable chlorine in this IPDI distillate was 85 ppm.

──────────────────────────────────────────────────続 き Continued on the front page (72) Katsutoshi Morinaka, Inventor 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko KK Chemical Research Laboratory (72) Inventor Toshihiko Tabuchi 3 Akubo, Tsukuba-shi, Ibaraki Chome 7-5 Louvre Mansion 201 (56) References JP-A-5-58982 (JP, A) JP-A-49-24916 (JP, A) (58) Fields studied (Int. Cl. ⁶ , (DB name) C07C 265/14 C07C 263/10 C07C 263/20

Claims (6)

(57) [Claims] (1) an aliphatic amine or a hydrochloride thereof,
Aliphatic alcohol contained in an amount of 3 to 25% by weight in terms of amine
Prepare an inert organic solvent solution (a) of min or its hydrochloride
And, Hosuge aliphatic amine or its hydrochloride in the solution (a)
Fat containing hydrolysable chlorine
The solution (b) of the aromatic isocyanate in an inert organic solvent was added under a pressure condition of 200 to 760 mmHg to 140 to 27 mmHg.
By heating to a temperature of 0 ° C., characterized in that from the solution (b), distilled off the solution of (b) aliphatic above solvent weight and the weight more than the amount of isocyanate in over a period of 2 hours A method for purifying an aliphatic isocyanate. (2) an aliphatic amine or a hydrochloride thereof,
Aliphatic alcohol contained in an amount of 3 to 25% by weight in terms of amine
Prepare an inert organic solvent solution (a) of min or its hydrochloride
And, Hosuge aliphatic amine or its hydrochloride in the solution (a)
Fat containing hydrolysable chlorine
The solution (b) of the aromatic isocyanate in an inert organic solvent was added under a pressure condition of 200 to 760 mmHg to 140 to 27 mmHg.
By heating to a temperature of 0 ° C., the from the solution (b), by distilling off the solution of (b) aliphatic above solvent weight and the weight more than the amount of isocyanate in over a period of 2 hours, then, A method for purifying an aliphatic isocyanate, which is obtained by distilling an aliphatic isocyanate from the obtained aliphatic isocyanate-containing substance. 3. An inert organic solvent solution (b) of said crude aliphatic isocyanate containing said hydrolyzable chlorine,
The method according to claim 1 or 2, wherein heating is performed at a temperature of 85 ° C for 3 to 6 hours. 4. The crude aliphatic isocyanate containing hydrolyzable chlorine is added in an amount equal to or more than the weight of the isocyanate.
The inert organic solvent solution of the obtained crude aliphatic isocyanate containing hydrolyzable chlorine is added at 200 to 760 mmHg while adding the inert organic solvent at once or gradually.
Of the pressure conditions, by heating at a temperature of one hundred forty to two hundred seventy ° C., the weight and the weight more than the amount of aliphatic isocyanates of the inert organic solvent solution over 2 hours, the inert organic solvent A method for purifying an aliphatic isocyanate, wherein the aliphatic isocyanate is gradually distilled off. 5. A crude aliphatic isocyanate containing hydrolyzable chlorine , the amount of which is equal to or greater than the weight of the isocyanate.
The inert organic solvent solution of the obtained crude aliphatic isocyanate containing hydrolyzable chlorine is added at 200 to 760 mmHg while adding the inert organic solvent at once or gradually.
Of the pressure conditions, by heating at a temperature of one hundred forty to two hundred seventy ° C., the weight and the weight more than the amount of aliphatic isocyanates of the inert organic solvent solution over 2 hours, the inert organic solvent A method for purifying an aliphatic isocyanate, which comprises gradually distilling off the mixture, and then distilling the aliphatic isocyanate from the obtained aliphatic isocyanate-containing substance. 6. An inert organic solvent solution of the crude aliphatic isocyanate is heated at a temperature of 150 to 185 ° C. to distill off the inert organic solvent for 3 to 6 hours. Item 6. The method according to item 4 or 5.