JPH06345707A - Method for purifying organic isocyanate compound - Google Patents

Abstract

PURPOSE:To obtain a method for reducing hydrolyzable chlorine in an organic isocyanate compound. CONSTITUTION:An inert gas is passed through a liquid organic isocyanate compound under conditions of 80-150 deg.C temperature and 0.1-100mmHg pressure. Thereby, hydrolyzable chlorine can efficiently be reduced without deteriorating and denaturing the organic isocyanate compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying an organic isocyanate compound. Organic isocyanate compounds are extremely reactive, react with active hydrogen compounds such as polyols and polythiols, and are used in various fields such as elastic bodies, foams, adhesives, high-grade elastic fibers, and optical plastic lenses.

[0002]

It is known that organic isocyanate compounds can be obtained by reacting the corresponding amines with phosgene in an inert solvent. The organic isocyanate compound obtained by the above method usually contains about 0.1 to 1% of hydrolyzable chlorine (hereinafter abbreviated as HC). The main component of this HC component is chlorine of a carbamoyl chloride compound obtained by adding hydrochloric acid to an isocyanate, and the hue of an organic isocyanate compound containing a carbamoyl chloride compound deteriorates over time, and the hue of a resin obtained from this is Also makes it worse. Furthermore, the carbamoyl chloride compound reacts with the active hydrogen compound to generate hydrochloric acid, which also adversely affects the production or quality of various polyurethane products.

For example, organic tin compounds such as dibutyltin dilaurate and dioctyltin dilaurate used in the urethanization reaction, metal salts such as manganese acetate, tin octylate and zinc octylate, diazabicycloundecene,
Urethane-forming catalysts for tertiary amines such as triethylamine, diazabicyclooctane and diethylaminoethanol are neutralized or decomposed in the presence of hydrochloric acid. Therefore, an excessive amount of catalyst is required accordingly.

Further, in urethane coating using a polyisocyanate compound containing a large amount of hydrolyzable chlorine, corrosion of the metal material is likely to occur.

As described above, since HC in the organic isocyanate compound has various adverse effects, it is necessary to reduce HC, and conventionally, various reducing methods have been proposed.

For example, zinc acetate, zinc bromide, zinc iodide, cadmium bromide, cobalt acetate, cobalt chloride, nickel chloride, copper chloride / manganese chloride (Japanese Patent Publication No. 42-17).
887), a saturated fatty acid zinc salt (JP-A-54-4461).
3) treatment methods with organic or organometallic compounds such as
A method using an HC treating agent is known. These methods can reduce HC to a low level of 10 ppm.

Further, as a method which does not use a special HC treating agent, crude diphenylmethane diisocyanate is used under normal pressure 2
A method of blowing nitrogen gas containing 5 wt% phosgene into the liquid phase portion under heating at 10 ° C to reduce HC from 0.40% to 0.28% (DD 271,820), 160 to 200 ° C.
1 preheated diphenylmethane diisocyanate
Continuous flow was made from the upper part of the packed column set to the conditions of 80 to 250 ° C / 100 to 300 mmHg, and nitrogen gas was aerated from the lower part, and HC was 0.3 to 1.7% to 0.1 to 0.1%.
Method of reducing to 0.5% (DE 2,237,55
2) etc. are known. These methods use 0.1% HC
It is effective in reducing to a relatively low level.

Hexamethylene diisocyanate was distilled (170 ° C./70 mmHg) to give 0.13% of HC.
From 0.003% to 0.003% (Japanese Patent Publication 6
1,161,250) is known, but the yield is 88%
And low.

[0009]

The problem with the method of using an HC treating agent such as an inorganic or organometallic compound is that the solubility of these HC treating agents in organic isocyanate is poor.
The C-treating agent itself and the metal compound produced not only accelerate the deterioration of the organic isocyanate due to polymerization, but also lower the yield.
There are problems that there is a risk of rapid thermal decomposition, and that distillation and refining are required to remove the HC treating agent after the HC treatment, and the yield is greatly reduced during that time.

On the other hand, in the method of aeration treatment with an inert gas under atmospheric pressure heating without using a special HC treatment agent, HC is treated with 0.1% or less.
It is difficult to reduce the level to 1% or less. Further, in the method of reducing HC to a low level of 0.1% or less by distillation purification, since it is exposed to high temperature for a long time, polymerization of organic isocyanate occurs, which causes a serious problem of reduction in yield.

The nitrogen gas AC treatment method using a packed tower requires a high temperature of 180 to 250 ° C., but the treatment time is short and the yield and purity are not significantly reduced.
It cannot be reduced to below.

Therefore, it has been desired to develop a method for solving these problems and efficiently reducing HC to 0.1% or less without lowering the yield and purity of the organic isocyanate.

[0013]

[Means for Solving the Problems] The present inventors diligently studied a method for efficiently reducing hydrolyzable chlorine in an organic isocyanate compound, and under the conditions of temperature and pressure within a specific range,
By injecting an inert gas into the liquid organic isocyanate compound, it was found that the purity and yield decrease can be suppressed to a minimum and the hydrolyzable chlorine in the organic isocyanate compound can be efficiently reduced, and the present invention has been completed. Came to do.

The treatment method of the present invention is characterized in that an inert gas is passed through the liquid organic isocyanate compound under reduced pressure or heating below the boiling point of the organic isocyanate compound, and the treatment is carried out under a reduced pressure of 100 mmHg or less. As a result, HC can be efficiently removed even at a relatively low temperature.

The conditions of the inert gas aeration treatment differ depending on the type of the organic isocyanate compound, the concentration of HC contained therein, and the like, but nitrogen, carbon dioxide, or argon gas is preferably used as the inert gas. The flow rate is 0.1 to 10 in terms of atmospheric pressure for 100 g of the organic isocyanate compound.
ml / min, preferably 0.5-5.0 ml / min
And the temperature is 80 to 150 ° C., preferably 100 to 13 under the conditions of not higher than the boiling point of the organic isocyanate compound.
The effect will be more excellent if it is carried out at 0 ° C. and the pressure is 0.1 to 100 mmHg, preferably 1 to 50 mmHg, and HC can be easily reduced to a low level.

When the flow rate of the inert gas is less than 0.1 ml / min with respect to 100 g of the organic isocyanate compound, the HC cannot be sufficiently reduced, and when it exceeds 10 ml / min, it is industrially necessary due to the capability of the decompression device. It becomes difficult to maintain the degree of pressure reduction, and the effect of reducing HC becomes insufficient.

On the other hand, if the heating temperature is lower than 80 ° C., the thermal decomposition rate of the carbamoyl chloride compound becomes slow, and sufficient H 2 content is obtained.
It takes a long time to reduce C and is not efficient.
If the temperature exceeds 150 ° C, the organic isocyanate compound is likely to be modified due to thermal deterioration, which is not preferable.

Further, if the pressure is lower than 0.1 mmHg, it is difficult as an industrial method due to the problem of the capacity of the pressure reducing device.
If it is higher than 100 mmHg, the hydrochloric acid produced cannot be efficiently removed out of the system due to thermal decomposition of the carbamoyl chloride compound, and sufficient HC reduction cannot be achieved.

The inert gas aeration treatment time depends on the type of organic isocyanate compound, the content of HC, the flow rate of the inert gas,
Although it depends on the processing temperature and pressure, it is usually 0.5 to 2
It is 4 hours, preferably 1 to 8 hours. Processing time is 0.
If it is shorter than 5 hours, the HC cannot be sufficiently reduced, and if it is longer than 24 hours, the organic isocyanate compound is likely to be modified due to thermal deterioration, which is not preferable.

The conditions for the organic isocyanate compound to which the present invention is applied are liquid at 150 ° C. or lower, and 80
It has a boiling point equal to or higher than the most mild condition of the present invention of ° C / 100 mmHg and is a liquid under the processing conditions of the present invention.

For example, monoisocyanate compounds such as phenyl isocyanate and benzyl isocyanate, ethylene diisocyanate, trimethyl diisocyanate,
Hexamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, 2,
2'-Dimethylpentane diisocyanate, 2,2,4
-Trimethylhexane diisocyanate, decamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, bis (isocyanatoethyl)
Aliphatic polyisocyanate compounds such as carbonate, 1,4-butylene glycol dipropyl ether-α, α'-diisocyanate, xylylene diisocyanate, thiodipropyl diisocyanate, thiodihexyl diisocyanate, isophorone diisocyanate Nato, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2′-dimethyldicyclohexylmethane diisocyanate, 2,5 (or 2,6) -bicyclo [2,2,1 Alicyclic polyisocyanate compounds such as heptane bis (methyl isocyanate), phenylene diisocyanate, toluene diisocyanate, ethyl phenylene diisocyanate, isopropyl phenylene diisocyanate, Methyl phenylene diisocyanate, diethyl phenylene diisocyanate, diisopropyl phenylene diisocyanate, naphthalene diisocyanate, methyl naphthalene diisocyanate, biphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl Examples thereof include aromatic polyisocyanate compounds such as diphenylmethane-4,4'-diisocyanate and diphenylsulfide-4,4'-diisocyanate.

[0022]

EXAMPLES The method of the present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 1 to 12 and Comparative Examples 1 to 5 2, which has 1000 ppm of HC and has a purity of 99.8%.
5 (or 2,6) -bicyclo [2,2,1] heptanebis (methyl isocyanate) (abbreviated as NBDI hereinafter) 1
An inert gas was blown into 00g under various heating and depressurization conditions shown in Table 1 (Table 1 and Table 2). Table 1 (Tables 1 and 2) shows the types and flow rates of the inert gas, the time, the HC content before and after the treatment, and the purity and yield of NBDI.

Comparative Example 6 NB containing 1000 ppm of HC and having a purity of 99.8%
DI 100 g was subjected to simple distillation at 150 to 160 ° C./4 mmHg. The product purity of NBDI is as good as 99.8%, but the yield is low at 90.5%, and HC is 520 ppm.
However, the effect of reducing HC was not sufficient.

Comparative Example 7 99.8% pure NB containing 1000 ppm HC
1.96 g of zinc stearate was added to 100 g of DI,
After stirring for 1 hour at 130 ° C, 150-160 ° C / 4m
Simple distillation was carried out at mHg. NB obtained by simple distillation
Although DI had a product purity of 99.8% and HC was sufficiently reduced to 20 ppm, the yield after distillation was extremely poor at 56.0%, and a resinous substance was produced in the distillation pot.

[0025]

[Table 1]

[0026]

[Table 2]

Examples 13 to 16 Various organic isocyanate compounds having a purity of 99.8% or more were subjected to an inert gas blowing treatment under heating and reduced pressure.
Table 2 (Table 3) shows the purity, HC content and yield of the organic isocyanate compound after the treatment.

[0028]

[Table 3]

[0029]

As described above, as a method of reducing HC of a high HC-containing organic isocyanate compound, the method of the present invention in which an inert gas is passed through the liquid organic isocyanate at a specific temperature and pressure range, Compared with the conventional method, H in the organic isocyanate compound can be efficiently produced in a high yield without deteriorating or modifying the organic isocyanate compound.
C can be reduced, which is an excellent industrial HC reduction method.

Claims (1)

[Claims] 1. A temperature of 80 to 150 ° C. and a pressure of 0.1 to 10.
An inert gas is bubbled through a liquid organic isocyanate compound at a flow rate of 0.1 to 10 ml / min in terms of atmospheric pressure with respect to 100 g of the organic isocyanate compound under the condition of 0 mmHg. Purification method.