JPH02311452A - Diisocyanate compound - Google Patents

Abstract

PURPOSE:To provide a diisocyanate compound having a chlorine-content lower than a specific level, useful for the production of polyurethane and having improved corrosion resistance, weather resistance, moisture resistance and heat resistance. CONSTITUTION:The content of chlorine in the objective compound is decreased to <=10ppm. The diisocyanate compound can be produced e.g. according to the reaction formula by reacting a dimethyl carbonate compound with a diamine at a molar ratio of 2-50 especially preferably using a basic substance such as sodium methylate as a catalyst and thermally decomposing the resultant urethane compound. The dimerization reaction can be suppressed and the yield of urethane compound can be improved by keeping the ratio of dimethyl carbonate/amine to the above level.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to novel diisocyanate compounds.

More specifically, the chlorine content is below a certain value.

Specifically, it relates to a novel diisocyanate compound having a concentration of 10 ppm or less.

(Technical background) Isocyanate compounds are industrially useful compounds,
Among these, diisocyanate compounds are particularly useful as raw materials for polyurethane.

(Prior art) Today, industrially, the total amount of diisocyanate compounds is
It is produced by the reaction of an amine compound and phosgene.

As is well known, phosgene is a highly selective and reactive substance.

However, it is also highly toxic, and its handling requires strict management.

Therefore, as long as production using phosgene continues, it is impossible to completely eliminate the risk of disasters associated with phosgene leakage.

In addition, the diisocyanate compound produced by the reaction of an amine compound and phosgene contains unreacted phosgene and chloroformate, which is a reaction by-product.

Alternatively, it contains impurities such as mono- and dicarbamoyl chloride compounds that are reaction intermediates.

(Problems to be Solved by the Invention) Furthermore, hydrogen chloride or chlorine, which is a byproduct of the phosgenation reaction, is contained as an impurity.

Usually, the above-mentioned hydrogen chloride or chlorine is contained in the diisocyanate compound in an order of over 1100 pp as a total chlorine content.

Even if the concentration is at the above level, if hydrogen chloride or chlorine is mixed in the diisocyanate compound, the following problems will occur.

That is, they are introduced into products in the polyurethane industry, where diisocyanate compounds are most commonly used, specifically in paints, elastomers, foams, etc., causing various problems.

For example, a monocarbamoyl chloride compound becomes a terminal group in the urethanization reaction between a diisocyanate compound and a diol, and inhibits the increase in the molecular weight of polyurethane.

Furthermore, the above-mentioned chlorine or chlorine compound reacts with water or moisture in the air to partially become chlorine ions.

These chlorine ions also have an adverse effect on the production or use of various polyurethane products.

For example, 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, triethylamine, diazabicyclooctane, and diethylaminoethanol. Urethanization catalysts such as tertiary amines are classified as Lewis bases, but these catalysts are neutralized or decomposed in the coexistence with chlorine ions.

Therefore, when using a diisocyanate compound produced by a method using phosgene, more than all of the urethanization catalyst that is inhibited by chlorine ions must be added, and an excess amount of the catalyst must be used.

Further, for example, chlorine ions are contained in urethane paints using diisocyanate compounds, which tends to cause corrosion of metal materials coated with urethane paints and blisters on the paint film itself.

As mentioned above, diisocyanate compounds containing chlorine or chlorine compounds have problems in production or use.

Note that no method has been found to date that can economically remove this chlorine content.

(Object of the Invention) An object of the present invention is to provide a diisocyanate compound in which the content of chlorine or chlorine compounds is controlled to be below a certain value.

Under these circumstances, the inventors of the present invention have completed the present invention as a result of intensive studies.

(Structure of the Invention) That is, the second invention is "a diisocyanate compound characterized by having a chlorine content of 10 ppm or less."

The above object can be achieved by a method of reacting an amine with dimethyl carbonate to form a urethane compound and further thermally decomposing it to obtain a diisocyanate compound.

This reaction consists of two stages, each represented by the following reaction formula.

1st stage reaction R(NH) + n CHa OCOCH3n R (N HCOCH) + n CHa OHn 2nd stage reaction R(NHCOCH3).

R(N-C-〇) + n CH30H■ First, in the first stage reaction, a basic substance such as sodium methylate is used as a catalyst, and a dimethyl carbonate compound and a diamine are reacted at a reaction molar ratio of 2 to 50 to form urethane. Synthesize a compound.

Dimethyl carbonate is used as a commercially available product, or after purification if necessary.

Amine compounds are classified into aromatic amine compounds and aliphatic amine compounds based on their chemical reactivity.

Particularly preferably used are aliphatic amine compounds.

Aliphatic amines are classified into alicyclic amine compounds that have an alicyclic skeleton in the molecule and chain aliphatic amines that have a chain skeleton, and can be suitably applied to chain aliphatic amines. Cyclic amines are particularly suitable. Examples of amine compounds that can be used in the present invention include the following amines.

As the alicyclic amine, isophoronediamine, 1.4-
Examples include diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, hydrogenated 4,4'-diaminodiphenylmethane, and hydrogenated toluylenediamine.

Diisocyanates with useful cyclic skeletons can be synthesized from these, so they are of high value. Among them, it is of industrial value to produce isophorone diisocyanate, a diisocyanate compound with excellent weather resistance, as the final product using isophorone diamine as a starting material. be.

Isophoronediamine has amino groups -NH2 and aminomethyl groups -CH2NH2 in the cis-position and trans-position in the cyclohexane ring, and both isomers can be used as raw materials for the present invention, and commercially available There is no problem even if it is a mixture of cis and trans forms like isophoronediamine.

A diamine in which the amino group is bonded to a saturated carbon and is preferably used as a raw material even if it has an aromatic ring in the skeleton.
Examples include m-xylylene diamine.

As the chain aliphatic amine, hexamethylene diamine, 2
, 2,4-trimethylhexamethylene diamine, 2,4
．． 4-) Dimethylhexamethylene diamine, tetramethylene diamine, 1,12-diaminododecane, and the like.

Although aromatic amines have inferior space-time yields or yields for urethanization compared to aliphatic amines, they can be urethanized using conventional techniques and used as the raw material of the present invention.

All amines may contain stable groups such as ether bonds, sulfone groups, carbonyl groups, and halogen groups in their skeletons.

It is preferable that the moisture content of the amines used be adjusted to less than ippm in advance.

The reason for this is to prevent the activity of the catalyst from decreasing as with water in dimethyl carbonate, which will be described later.

Moreover, the first method of producing an isocyanate compound of the present invention
The basic substances used as catalysts in the step reaction are alcolades of alkali metals and alkaline earth metals,
Examples include methylates, ethylates, tert-butyrates of lithium, sodium, potassium, calcium and barium.

Basic substances are used both in solid form and in solution.

Among the above substances, sodium methylate is particularly preferred because it is easily available and economical.

The amount of sodium methylate used in the present invention is not an economically significant amount, and it is not necessary to recycle it.

Therefore, the equipment becomes simple.

Furthermore, sodium methylate is commercially available as a methanol solution crystal and is easy to handle.

The manufacturing method of the present invention does not require pressurization and can be carried out satisfactorily at normal pressure, but can also be carried out satisfactorily under pressurized conditions that compensate for the pressure loss due to the structure of the apparatus.

In addition, dimethyl carbonate/diamine at a molar ratio of 2 to
50 (dimethyl carbonate/amino group molar ratio -1~
25) is preferable.

In particular, it is preferred that the molar ratio of dimethyl carbonate/amine be 4 or more.

The reason why the molar ratio of dimethyl carbonate/amine is 2 to 50 is that the trimerization reaction is suppressed and the yield of the urethane compound is inevitably improved.

It should be noted that if the amount of dimethyl carbonate used is 50 times the mole or more, it will not be effective.

The dimethyl carbonate used preferably has a moisture content of less than 0.2%.

The reason for this is that water in dimethyl carbonate reacts with the catalyst to form metal hydroxides, and since metal hydroxides do not have catalytic activity, it is necessary to increase the amount of catalyst used.

Dimethyl carbonate produced by conventional methods has a relatively water-soluble property, and there is a high risk of water contamination.

The amount of alkali catalyst used is determined depending on the activity of the catalyst so that the reaction is completed in a practical time.

In the case of sodium methylate, the reaction crude liquid contains 0°001~
The reaction proceeds with addition of 5% by weight, preferably 0.1 to 3% by weight.

When the amount of sodium methylate used is less than 0.001% by weight, the reaction is slow, and when it is more than 5% by weight, precipitation of the catalyst becomes a problem, which is also economically disadvantageous.

In order to manage the heat of reaction, it is preferable to drop the amine compound into dimethyl carbonate.

It is practically possible to select the reaction temperature in the range from 0°C to the boiling point of the crude reaction liquid, but since the reaction is slow at low temperatures and the boiling of by-product methanol becomes intense at high temperatures, it is recommended to select the reaction temperature from 30°C to the boiling point of the crude reaction liquid. It is preferable to select the temperature within the range of 80°C.

When the raw material is solid or when it is desired to prevent the precipitation of the urethane compound produced, there is no problem in using a solvent, such as methanol, ethanol, tetrahydrofuran, dioxane, benzene, toluene, etc., which are inert to the raw material and the product. Solvents can be used.

The type and amount of solvent is selected and used depending on the reaction conditions so as to dissolve raw materials or products that are difficult to dissolve. However, if the amount used is large or the dilution rate is high, the progress of the reaction will slow down, which is disadvantageous. Advantageously, the amount is kept to the minimum required for dissolution.

It is desirable to use 1 to 10 times the amount of the urethane compound to be produced.

In addition, when the molar ratio of dimethyl carbonate/diamine compound in the starting material is close to 2, the concentration of the urethane compound produced in the crude solution of one reaction will be high, so if the urethane compound is highly crystalline, there is a risk of precipitation. To prevent this, it is necessary to choose a solvent with high dissolving power.

In addition, the boiling point of the solvent is 10°C higher than that of the urethane compound produced.
It is economically advantageous to use a compound having a lower boiling point than that mentioned above because it facilitates distillation and purification.

In the raw material mixing method, especially in the case of batch reactions, it is better to use continuous addition or multiple intermittent divided addition methods as the first-stage reaction progresses to reduce the amount used by half compared to the batch addition method. It is preferable because it can be reduced to ~1/3.

Although the reason for this is not clear, it has been found that the amount of catalyst used can be reduced if the catalyst is added continuously or intermittently during the reaction as shown in the Examples.

If the charging speed of the diamine catalyst is high, the by-product methanol will boil violently, so it is necessary to control the charging speed of the catalyst as well as the reaction temperature.

Furthermore, when the first stage reaction is carried out in a continuous manner, the diamine catalyst may be charged not only from the inlet of the reactor but also from the middle of the reactor.

For example, when the reaction crude liquid is passed in series into several complete mixing tanks, a method can be adopted in which the catalyst is divided into six tanks and charged.

The produced crude urethane compound liquid can be purified to the required purity using general purification methods such as distillation, crystallization, water washing, and reprecipitation.

Among these, first, the alkaline content derived from the metal alcoholade, which is a basic catalyst, is neutralized using phosphoric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, etc., and then the excess added acid component is removed by washing with water.

This neutralization step is necessary because when the basic catalyst is heated together with the urethane compound, it further changes the urethane compound into an unintended high boiling point product.

Salts generated during neutralization can be removed by common methods such as water washing, filtration, and centrifugation, and are carried out in combination with methanol removal.

Furthermore, a method in which the urethane compound is purified by flash evaporation is preferred.

Next, this urethane compound was converted into partially hydrogenated triphenyl,
An elemental metal or a compound such as manganese or molybdenum that becomes a catalyst is added as a methanol solution in a high boiling point solvent such as m-terphenyl.

The isocyanate compound is obtained by thermal decomposition.

The decomposition reaction of a urethane compound is a sequential reaction as follows.

R(NHCOCH3) 2 Urethane compound NHCOCH3 R< +
CH30H-C-0 monoisocyanate 11°NHCOCH3 By carrying out the reaction under reduced pressure where the diisocyanate compound to be produced is distilled out, the concentration of the diisocyanate compound in the reaction system is kept low, and the following addition reactions such as dimerization and trimerization of the isocyanate group and the following addition reaction between the NH group of the urethane bond and the isocyanate group are carried out. control and achieve high yields.

HO 1l -N-C-0+-NCOR → HO 1l -N-,CO N-COR Compounds used as catalysts include metal manganese,
Manganese oxide (MnOl or Mn203) manganese chloride, manganese sulfate, manganese phosphate, manganese borate, manganese carbonate, manganese acetate, manganese naphthenate,
Manganese(n) acetylacetonate, Manganese(II)
I) Acetylacetonate, metallic molybdenum, molybdenum dioxide, molybdenum acetylacetonate (MoO2
(acac) 2) Examples include molybdenum dioxide, metallic tungsten, tungsten hexacarbonyl, tungstic anhydride, and tungstic acid.

These can be used in the form of hydrated salts or in anhydrous form.

Manganese chloride, manganese sulfate, manganese acetate, and manganese naphthenate are particularly preferred because they are industrially easily available, inexpensive, and highly active.

In particular, manganese acetate is preferable because it has sufficient activity at a low concentration in the crude reaction solution.

The optimal amount of the catalyst to be used is determined depending on the reactivity of the raw materials used, the lH degree, and the type and amount of the catalyst.

If the amount is too small, the reaction will be slow, and if it is too large, high boiling by-products will tend to increase.Usually, when the amount of catalyst in the solvent is 0,
The range from 0.0005% to 5% by weight is most preferred.

If the reaction temperature is lower than 150°C, the generation of the diisocyanate compound will be slow, making it impractical, and if it is higher than 300°C, it will be difficult to carry out industrially, which will be disadvantageous.

That is, the temperature is preferably from 150°C to 300°C.

The solvent must be inert to the target products, diisocyanate compounds and urethane compounds, and must be inert to aliphatic compounds, aromatic compounds, alkylated aromatic compounds,
It can be selected from ether compounds and the like.

It can be used as a solvent even if it contains an inert group such as a halogen group.

Further, the solvent is preferably one that can be easily purified and separated from the diisocyanate compound that is the target product.

A solvent whose boiling point is different from that of the diisocyanate is preferable because it can be purified and separated by distillation.

If the boiling point of the solvent is lower than that of the diisocyanate compound to be produced, it will be distilled out together with the diisocyanate compound, which is disadvantageous in that it will complicate the process in practice, so a solvent having a boiling point higher than that of the diisocyanate to be produced is preferred.

Further, a solvent having a boiling point higher than that of the diisocyanate compound to be produced by 10° C. or more is particularly preferred since it can be easily separated and purified by distillation in a subsequent step.

Furthermore, since high-boiling reaction by-products accumulate in the solvent over time, it is desirable to use a solvent with a boiling point that allows industrial regeneration.

Preferred solvents include 0-terphenyl, m-terphenyl, p-terphenyl, mixed diphenylbenzene,
Partially hydrogenated triphenyl, dibenzylbenzene, biphenyl, phenyl ether, phenylcyclohexane, hexadecane, tetradecane, octadecane, icosane,
Examples include benzyl ether and tetramethylene sulfone.

A suitable solvent should be selected depending on the desired diisocyanate compound; for example, partially hydrogenated triphenyl is particularly preferred in the production of isophorone diisocyanate.

The reaction is carried out under reduced pressure so that the diisocyanate compound produced from the reaction system is distilled out.

This keeps the concentration of diisocyanate compounds in the system low and achieves a high reaction yield, but this effect is particularly effective when the reaction is carried out under boiling solvent, and from this point of view the reaction pressure is controlled by the reaction temperature. It is preferable to carry out the reaction at a reduced pressure at which the solvent boils.

If the degree of reduced pressure is too high, it will be difficult to recover by-product alcohol and it will be disadvantageous in terms of equipment and utility, so it is usually preferred to be at least ITorr and at most 700 Torr.

The urethane compound, solvent, and catalyst, which are raw materials for the thermal decomposition reaction, are continuously supplied to the reaction system.

The solvent in the reactor is continuously withdrawn together with high-boiling by-products in the solvent, and at the same time the reactor is replenished with high-boiler-free solvent.

It is advantageous to purify and reuse the extracted solvent as described later.

Since the catalyst is also lost along with the solvent that is removed, the same amount of catalyst as lost is continuously charged to keep the catalyst concentration constant.

The urethane compound and the solvent may be prepared in advance and charged to the reaction system.

When manganese acetate is used as a catalyst, it has conventionally been used in the form of a methanol solution, taking advantage of the high solubility of manganese acetate in methanol.

The main purpose of dissolution is to make the catalyst easier to handle when it is a solid or viscous substance by turning it into a solution.
The temperature in the reaction system was higher than the boiling point of methanol, and methanol sometimes evaporated and the catalyst precipitated.

If the methanol solution is further dissolved in a diisocyanate compound, which is the target product, and added, since the boiling point of the diisocyanate is high, it is effective in preventing precipitation of the catalyst.

First, the catalyst is dissolved in methanol to obtain a catalyst solution.

The mixing ratio of the catalyst and methanol is such that the solution becomes a homogeneous solution with low viscosity, or it is necessary to use methanol in an amount greater than that.

A large amount of methanol is uneconomical.

The weight ratio of methanol to the catalyst is selected depending on the catalyst, but it is usually preferable to use 0.2 to 1000 times the weight of the catalyst.

At this time, care must be taken to prevent methanol from reacting with the isocyanate compound and returning to the urethane compound.

Compounds with urethane groups usually have a higher melting point and viscosity than compounds with isocyanate groups.

That is, it is preferable to set the ratio so that the viscosity does not increase even if the isocyanate compound and methanol are completely reacted.

In addition, even if methanol is in excess of diisocyanate, the viscosity is low due to the dilution effect of methanol, so it can be carried out, but in a composition with excess methanol, methanol will evaporate rapidly when charged to the reaction system, so measures such as heating are required. It may be necessary.

The reason why a catalyst that is insoluble in diisocyanate is mixed with diisocyanate after dissolving in methanol to obtain a homogeneous liquid is unknown, but it is possible that the urethane bonds formed are polar and coordinate with the catalyst and become solubilized. is possible.

The reason why methanol is preferable is that it is a substance produced by decomposition and does not require a complicated purification system.

If the reaction solvent dissolves the required amount of the catalyst, it can be prepared as a solvent solution, but the reaction solvent is usually nonpolar and often has insufficient dissolving power, so this method is effective. The reason why the solution is mixed in the above order is that the manganese compound does not dissolve in the diisocyanate compound but easily dissolves in methanol.

Further, the number of stages of the distillation column to be used is selected depending on the physical properties of the urethane compound to be decomposed, the diisocyanate to be produced, and the solvent. This method is effective regardless of the number of stages. Practically speaking, it can be suitably carried out using a distillation column having 1 to 100 stages. 10
Equipment costs for towers with 0 or more stages are high.

Although charging the catalyst liquid into the distillation column anywhere within the column is more effective than charging it into the reactor,
Since the reaction zone is located below the charging position of the catalyst solution, it is not preferable if the charging position in the distillation column is too low because decomposition of the monoisocyanate will be insufficient.

On the other hand, if the charging position in the distillation tower is too high, the catalytic
& Since the monoisocyanate in the solution is distilled out, it is rather disadvantageous, so the optimal position for balance should be selected depending on the diisocyanate to be produced.

In addition, in order to reduce the amount of solvent and unreacted raw materials mixed into the diisocyanate compound, which is the target product, the steam generated from the reactor is led to a distillation column equipped with a reflux device, and the fraction rich in diisocyanate compounds is transferred to the upper part of the column. It is particularly advantageous to use a reaction apparatus having a structure such as that obtained in , since purification of the diisocyanate compound becomes easy.

In addition, high-boiling byproducts are generated in the solvent over time, and these byproducts undergo an addition reaction with the isocyanate groups of the diisocyanate compound that is the product, resulting in a decrease in the yield of the isocyanate compound.

As a method to prevent this, the crude liquid mixture in one reactor is continuously withdrawn and flash evaporated to remove high boiling point by-products, which are the residue of the flash evaporator, and at the same time, the mixture rich in high boiling point solvent is released. This is done by condensing the solvent and returning the mixture of the condensed solvent, unreacted urethane compound, and product diisocyanate compound to the reactor.

Of course, high-boiling byproducts may be removed by distillation using a distillation column instead of flash distillation.

At this time, the catalyst is also lost along with the high-boiling byproducts that are extracted, so a corresponding amount is added to the reaction system.

Although it is possible to recover and reuse the catalyst.

The catalyst used in the process of the invention is relatively inexpensive;

Since the amount used is small, the cost will not increase much even if it is disposable.

In addition, in thermal decomposition reactions, not only catalysts are used.

The use of a cocatalyst significantly improves the yield of isocyanate compounds.

Particularly preferred cocatalyst used is tristylphosphite.

Specific examples of tristylphosphite include phosphite trialkyl esters such as triethyl phosphite and tributyl phosphite, and triphenyl phosphite.

Examples include phosphorous acid triaryl esters such as tritolyl sulfite.

Among these, esters with a high boiling point such as triphenyl phosphite are preferred because they are less likely to volatilize during the reaction.

When using tristyl phosphite, the amount added is 0.01 to 10,000 times the weight of the manganese compound,
If the amount is less than 0.01 times by weight, there is no effect of adding it, and if it exceeds 10,000 times by weight, the effect will not improve any further, which is not preferable.

The diisocyanate compound of the present invention containing 10 ppm or less of chlorine or a chlorine compound can be obtained as described above.

(Effects of the Invention) Corrosion resistance of urethane paints or other polyurethane industrial products is improved by using a diisocyanate compound containing 10 ppm or less of chlorine.

Further, the urethanization catalyst is not inhibited by chlorine ions.

Therefore, it is possible to reduce the amount of catalyst used. As a result, the content of amines, metal salts, etc. in the polyurethane is reduced, so that the weather resistance, moisture resistance, and heat resistance of the polyurethane are improved.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

[Synthesis Example-1] Isophoronediamine 85g 1 dimethyl carbonate 36
0 g was placed in a round bottom flask equipped with a stirrer, stirred, and heated to 70° C. under a nitrogen stream.

Next, a 28% methanol solution of sodium methylate8.
9 g was added dropwise over 10 minutes, and after further aging for 50 minutes, the reaction crude liquid was analyzed by gas chromatography, and it was found that a diurethane compound corresponding to isophorone diamine, that is, isophorone cicabamate, was produced in a yield of 91% based on isophorone diamine. I confirmed that there is.

[Synthesis Example-2] 360 g of dimethyl carbonate was charged into a round bottom flask equipped with a stirrer, and the temperature was raised to 70° C. under a nitrogen stream while stirring.

Next, in the above flask, 8.9 g of a 28% methanol solution of hesodium methylate and 85 g of isophorone diamine.
was charged over 2 hours at an even feeding speed using two feeding pumps.

During this time, the temperature of the reaction crude liquid was maintained at 70°C.

Furthermore, after the preparation is completed, it is aged for 3 hours at the same temperature.

Gas chromatography analysis of the reaction crude solution neutralized with phosphoric acid revealed that the yield of diurethane compound 1 corresponding to isophorone diamine, that is, isophorone cicabamate, was 99% relative to isophorone diamine, and the yield relative to the consumed dimethyl carbonate was 99%. It was confirmed that it was generated at a rate of 99%.

[Synthesis Example 3 Synthesis Example 11 The following reaction was carried out in the same apparatus as Synthesis Example 2.

723.1 g of dimethyl carbonate held at 70°C
Hexamethylene diamine 1 is placed in a reactor containing
21.1 g of sodium methylate and 17.3 g of a 28% methanol solution were divided into four portions and added dropwise every 30 minutes.

After completion of the dropwise addition, the mixture was further aged at 70°C for 1 hour, titrated with 1/10N H (do4), and as a result of correction for methylate, it was confirmed that the amine had been converted at a conversion rate of 99.6%. did.

After that, 859 was also neutralized with 7.5 g of phosphoric acid and the crude reaction solution was analyzed by gas chromatography.

It was confirmed that 1.6bis(methoxycarbonylamino)hexane was produced at a yield of 98.4% based on the diamine.

Example-1 300 m in a 10-stage Aldershaw tower made of glass with a reflux device
Set a flask and add Nippon Steel Chemical Co., Ltd. Sum 5900 solvent (partially hydrogenated triphenyl)] 000 g manganese acetate 4
Pour 0.05g of water and heat under reduced pressure until the can liquid reaches 230g.
The degree of vacuum was adjusted to boil at ℃.

Next, 1,6-bis(methoxycarbonylamino)-hexane was dropped into the flask at a rate of 60 g/Hr from a double-pipe dropping funnel heated with a heating medium to a fluidizing temperature.

After the start of charging, a liquid rich in hexamethylene diisocyanate rose into the column, so this was distilled from the top of the column at a distillation rate commensurate with the dropping rate of 1°6-bis(methoxycarbonylamino)-hexane. .

After 2 hours of operation, distillation was continued until no isocyanate was generated, and then the operation was stopped.

Charged 1,6-bis(methoxycarbonylamino)-
The presence of hexamethylene diisocyanate (HDI) with a yield of 55% and monoisocyanate with a yield of 19% with respect to hexane was confirmed in the distillate.

Example-2 200m1 with 20-stage Aldershaw tower set! Continuous decomposition of 3-methoxycarbonylaminomethyl-3,5,5-)dimethyl-1-methoxycarbonylaminosiloxane (abbreviated as isophorone cica-bamate, abbreviated as (■PDc) was carried out using a large capacity glass reboiler. .

m-terphenyl was used as a solvent.

The first 200 m [m-terphenyl and m
- Manganese acetate anhydride equivalent to 10 ppm of terphenyl was charged and heated until the underlined state was reached under a reduced pressure of 10 Torr.

Then IPDC 59.0% by weight, m-terphenyl 41
．． A 0% by weight mixed solution was charged at a rate of 120 g/Hr.

The m-terphenyl solution of I PDC was charged to the fifth stage from the bottom of the Aldershaw tower.

The product, isophorone diisocyanate (abbreviation: IPD), was withdrawn from the top of the distillation column, and the reactor was operated at a bottoms withdrawal rate such that the liquid level of the reactor remained constant.

[Measurement of total chlorine content] The total chlorine content in the obtained isocyanate compound is AS
It was measured based on the method of TM D-1638.

The total chlorine content in the inphorone diisocyanate obtained in Example-2 was 0.2 ppm.

On the other hand, the total chlorine content in a commercial product of isophorone diisocyanate produced by the phosgene method was measured in the same manner and was found to be 245 ppm.

Further, the total chlorine content in the hexamethylene diisocyanate obtained in Example-1 was also 0.2 ppm.

Claims (2)

[Claims] (1) A diisocyanate compound characterized by having a chlorine content of 10 ppm or less. (2) The compound according to claim (1), wherein the diisocyanate is isophorone diisocyanate.