JPH06172292A - Production of diisocyanate compound - Google Patents

Abstract

PURPOSE:To provide a process for producing a diisocyanate compound without using phosgene during the production processes. CONSTITUTION:The production process comprise the steps of reacting carbon monoxide, oxygen and methanol with each other to produce dimethyl carbonate; (6) reacting the dimethyl carbonate with a diamine in the presence of an alkali catalyst to produce an urethane compound; and (c) pyrolyzing the urethane compound in the presence of a catalyst under a vacuum of 1-700Torr to produce the diisocyanate compound. Since the produced diisocyanate compound is substantially free from chlorine, the materials of instillations in the production processes can be selected from a variety of fields.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing a diisocyanate compound comprising three steps. More specifically, carbon monoxide, oxygen and methanol are reacted to obtain dimethyl carbonate, then the dimethyl carbonate is reacted with diamine to obtain a urethane compound, and then the urethane compound is heated. The present invention relates to a method for producing a diisocyanate compound, which comprises a three-step process of decomposing.

[0002] Isocyanate compounds are industrially useful compounds, and diisocyanate compounds are particularly useful as raw materials for polyurethane.

[0003]

2. Description of the Related Art Today, all diisocyanate compounds are industrially produced by reacting an amine compound with phosgene.

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

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

Therefore, as long as the production using phosgene is continued, it is impossible to eliminate the risk of disasters caused by leakage of phosgene. In addition, the diisocyanate compounds produced from phosgene contain a significant amount of chlorine.

As a method for producing a diisocyanate compound from an amine compound without using phosgene, a method of reacting an amine compound with urea and alcohol to produce a urethane compound first and then thermally decomposing the urethane compound in a gas phase Have been proposed [JP-A-59-205352, JP-A-59-205353, etc.].

However, in these examples, the first step is carried out at a pressure of 6 to 8 bar, and the second step is carried out in the gas phase at a reaction temperature of 410 ° C., which is an expensive manufacturing method. Will end up. A method of using dimethyl carbonate instead of the above urea and alcohol is considered. Dimethyl carbonate is a safe compound that does not require special abatement equipment or monitoring compared to phosgene.

[0009]

Most dimethyl carbonates are also made from phosgene, where the dimethyl carbonates contain significant amounts of chlorine.

Further, a diisocyanate compound obtained by reacting dimethyl carbonate produced from this phosgene with an amine compound to produce a urethane compound and then thermally decomposing the urethane compound is a diisocyanate produced by the phosgene method. -It has a lower content than the tho compound but still contains a considerable amount of chlorine.

Dimethyl carbonate can also be produced from inexpensive methanol, carbon monoxide and oxygen [see, for example, Japanese Patent Application No. 61-201568 (JP-A-63-57552),
Japanese Patent Application No. 61-215178 (JP-A No. 63-72650), Japanese Patent Application No. 61-215179
(JP-A-63-72651) and the like]. The dimethyl carbonate obtained by the above method contains almost no chlorine. As a result of diligent studies by the present inventors under such circumstances, the methano-
It is economically advantageous if a diisocyanate compound is obtained in good yield by a thermal decomposition to obtain a urethane compound using a dimethyl carbonate produced from hydrogen chloride, carbon monoxide and oxygen, and the phosgene method. It has been found that the diisocyanate compound in this case has various advantages because it contains almost no chlorine, and has reached the present invention.

[0012]

An object of the present invention is to react a chlorine-free dimethyl carbonate with an amine compound in the presence of an alkali catalyst to give a urethane compound, which is then pyrolyzed in a high-boiling solvent. Another object of the present invention is to provide a method for industrially producing a diisocyanate compound containing no chlorine.

[0013]

That is, the present invention provides "the following three steps (a) a step of reacting carbon monoxide, oxygen and methanol to obtain dimethyl carbonate (b) the above dimethyl carbohydrate. A step of reacting a carbonate with a diamine in the presence of an alkali catalyst to obtain a urethane compound (c) a step of thermally decomposing the above urethane compound under reduced pressure of 1 to 700 Torr to obtain a diisocyanate compound And a method for producing a diisocyanate compound.

The above three steps of reactions are represented by the following reaction equations.

[0015] The following three steps (a), (b) and (c)
The step reactions will be described in detail in order.

The above-mentioned Japanese Patent Application No. 61-201568 (Japanese Patent Laid-Open No. 63-57552)
No.), Japanese Patent Application No. 61-215178 (JP-A No. 63-72650), Japanese Patent Application No. 61-2.
15179 (JP-A-63-72651) and the like, starting materials in step (a) are carbon monoxide, alcohol and oxygen, which are reacted in the presence of a catalyst under atmospheric pressure or pressure. .

The catalyst used is a divalent copper salt, specifically, copper acetate, copper pivalate, copper benzoate and other carboxylic acid copper salts, copper hydrobromide, copper carbonate and phenols. Examples thereof include weak acid copper salts such as copper salts and halides such as cupric chloride and cupric bromide.

The amount of these divalent copper salts used is 1 alcohol.
1-3000 mmol per liter, preferably 1
0 to 1000 mmol.

An alkaline earth metal halide is further used in combination with the above catalyst.

Specific examples of alkaline earth metals are beryllium, magnesium, calcium and barium, and their chlorides, iodides, acetates and the like are used. The amount of alkaline earth metal compound used is 1/1 with respect to the divalent copper salt.
The molar ratio of halogen to copper (halogen / copper) is preferably more than 1/2 and less than 2 in the catalyst system.

The catalyst used is not limited to the above-mentioned divalent copper salt, but may be a platinum group compound such as ruthenium, palladium or rhodium.

These are used in the form of halides, acetates and nitrates.

However, when a chloride is used as a catalyst, the chlorine concentration in the obtained dimethyl carbonate is slightly higher.

When these platinum group compounds are used in combination, the amount is equimolar or less, preferably 1/10 mol or less with respect to the divalent copper salt.

The starting materials of this method other than alcohol are carbon monoxide and oxygen, but these do not require particularly high purity, and are nitrogen, argon, carbon dioxide, and other inert gases in the reaction. You may use what diluted.

The reaction is carried out at 1 to 100 atm. When the reaction system is diluted with an inert gas, the partial pressure of carbon monoxide is 0.1 to 10 atm and the partial pressure of oxygen is 0.1 to 10 atm. It is good to use atmospheric pressure. The reaction temperature is preferably in the range of 20 to 250 ° C.

Dimethyl Carbide Produced as Above
Even if a chlorine compound (copper halide, etc.) is used as a catalyst, the chlorine content in the carbon dioxide is at most 10 ppm, usually 5 ppm.
It is about ppm, and the chlorine content in the diisocyanate compound when the diisocyanate compound is produced by the reaction with the diamine described below also becomes a smaller value. It is known that the chlorine content in dimethyl carbonate produced using phosgene is 150 to 1000 ppm.

Therefore, when a diisocyanate compound is produced by reacting dimethyl carbonate having such a chlorine content with diamine, the chlorine content in the obtained diisocyanate compound is 15 to 60 pp.
m, that is, 10% of chlorine in dimethyl carbonate
The degree is carried over into the diisocyanate compound.

Amine compounds are classified into aromatic amine compounds and aliphatic amine compounds based on their chemical reactivity. Aliphatic amine compounds are particularly preferably used.

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

As the alicyclic amine, isophorone diamine, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, hydrogenated 4,4'-diamino Examples include diphenylmethane and hydrogenated toluylenediamine.

Since a useful diisocyanate having a cyclic skeleton is synthesized from these, it is of high value. Among them, isophorone diisocyanate, which is a final product and is excellent in weather resistance, is used to produce isophorone diisocyanate from isophorone diamine as a starting material. Has industrial value.

Isophoronediamine includes amino group --NH.
₂ and the aminomethyl group —CH ₂ NH ₂ are in the cis position and the trans position in the cyclohexane ring, both isomers being used as the raw material of the present invention,
A mixture of cis and trans forms such as commercially available isophoronediamine may be used.

A diamine having an amino group bonded to a saturated carbon and having an aromatic ring in the skeleton is preferably used as a raw material, and examples thereof include m-xylylenediamine.

Examples of chain aliphatic amines include hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, tetramethylenediamine, and 1,12-diaminododecane. .

Although aromatic amines are inferior in space-time yield or yield of urethanization to aliphatic amines, they can be urethanized using conventional techniques and used as a raw material of the present invention.

All amines may have stable groups such as ether bond, sulfone group, carbonyl group and halogen group in the skeleton.

The amine used has a water content of 1
It is preferable to keep less than%. The reason for this is to prevent the activity of the catalyst from being lowered, like the water content in dimethyl carbonate described later.

The basic substance used as a catalyst in the step (b) of the second step of the method for producing a diisocyanate compound of the present invention is an alkali metal or alkaline earth metal alcoholate. Examples thereof include lithium, sodium, potassium, calcium, barium methylate, ethylate, and tert-butyrate.

The basic substance is used in a solid state or a solution state.

Among the above substances, sodium methylate is particularly preferable because it is easily available and economical. The amount of sodium methylate used in the present invention is not an amount having an economical impact, and it is not always necessary to recycle it.

Therefore, the equipment becomes simple.

Moreover, sodium methylate is a methanol
Solution products are on the market and easy to handle. The production method of the present invention does not require pressurization and can be sufficiently carried out at normal pressure, but can be well carried out even under pressurizing conditions to the extent of compensating for pressure loss in the device structure.

Further, it is preferable that the molar ratio of dimethyl carbonate / diamine is 2 to 50 (the molar ratio of dimethyl carbonate / amino group = 1 to 25).

Especially, it is preferable that the molar ratio of dimethyl carbonate / amine is 4 or more.

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

The amount of dimethyl carbonate used was 5
When the amount is 0 times or more, it becomes ineffective. The dimethyl carbonate used preferably has a water content of less than 0.2%. The reason is that the water content in dimethyl carbonate reacts with the catalyst to form a metal hydroxide, and since the metal hydroxide does not have a catalytic action, it is necessary to increase the amount of the catalyst used. is there.

Dimethyl carbonate produced by a conventional method has a property of relatively dissolving water, and there is a high risk that water will be mixed.

The amount of the 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, 0.001-in the crude reaction liquid
The reaction proceeds with the addition of 5% by weight, preferably 0.1 to 3% by weight.

The amount of sodium methylate used is 0.00
If it is less than 1% by weight, the reaction is slow, and if it is more than 5% by weight, the precipitation of the catalyst becomes a problem, which is economically disadvantageous.

From the viewpoint of controlling the heat of reaction, it is preferable to drop the amine compound into dimethyl carbonate.

Although it is practically possible to select the reaction temperature in the range from 0 ° C. to the boiling point of the reaction crude liquid, the reaction is slow at low temperature and the boiling of methanol by-produced becomes high at high temperature. It is preferable to select in the range of 30 ° C to 80 ° C.

If the raw material is a solid or if it is desired to prevent the precipitation of the urethane compound formed, a solvent may be used, and for example, methanol, ethanol, tetrahydrofuran, dioxane, benzene, toluene, etc. may be used for the raw material and the product. A solvent that is active can be used.
The solvent is used by selecting the type and amount according to the reaction conditions so as to dissolve the raw material or product that is difficult to dissolve, but if the amount used is large and the dilution rate is high, the reaction will proceed slowly and is disadvantageous. Advantageously, the amount is kept to the minimum required for dissolution.

The solvent is 1 for the urethane compound produced.
It is desirable to use 10 to 10 times the amount.

When the molar ratio of the dimethyl carbonate / diamine compound in the starting material is close to 2, the concentration of the urethane compound formed in the reaction crude liquid becomes high, so that the crystallinity of the urethane compound is high. In this case, it is necessary to select a solvent with a high dissolving power to prevent the risk of precipitation.

Further, it is economically advantageous to use a solvent having a boiling point lower than that of the urethane compound to be produced by 10 ° C. or more, because distillation purification becomes easy.

In the mixing method of the raw materials, particularly in the case of a batch reaction, the catalyst addition method is a continuous addition method or a plurality of intermittent divided addition methods as the reaction progresses, and the amount used is half that of the batch addition method. It is preferably 1/3, which is preferable.

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

When the charging rate of the diamine catalyst is high, the boiling of the by-produced methanol becomes vigorous, so it is necessary to control the charging rate of the catalyst along with the reaction temperature. Further, when the reaction is carried out continuously, it is possible to charge the diamine catalyst not only at the inlet of the reactor but also at the intermediate part of the reactor.

For example, when the reaction crude liquid is flowed in series into several complete mixing tanks, the catalyst may be divided and charged into each tank.

The resulting crude urethane compound liquid can be purified to a required purity by a general purification method such as distillation, crystallization, washing with water and reprecipitation.

Among them, first, phosphoric acid is used to neutralize the alkaline component derived from the metal alcoholate which is the basic catalyst,
Excessly added phosphoric acid is removed by washing with water.

As the acid for neutralizing the metal alcoholate, other acids such as sulfuric acid, formic acid, oxalic acid and acetic acid may be used.

When the basic catalyst is heated together with the urethane compound, the urethane compound is further changed to a high-boiling substance which is not intended, so that this neutralization step is necessary.

The salt formed in the neutralization step can be removed by a general method such as washing with water, filtration or centrifugation.
It is carried out in combination with the operation for removing the resin.

Further, a method of purifying the urethane compound by flash evaporation is preferable.

The advantages of using phosphoric acid for neutralization are as follows.

That is, if the addition amount is too large or too small, the fluctuation range of the PH is small, and the urethane compound is hardly adversely affected in the subsequent purification step.

Further, a method in which the urethane compound crude liquid is washed with a benzene / water system and then purified by distillation has the same effect. Benzene is preferable because it easily dissolves the urethane compound and has low solubility in water.

The ratio of the amount of benzene to the amount of water used is such that the urethane compound dissolves in benzene at the temperature of the washing treatment, that is, usually 1 to 10 relative to water.
It is double.

Since the solubility varies depending on the type of urethane compound produced, the solubility is selected within the above range.

In addition to benzene, aromatic compounds such as toluene and xylene, halogenated hydrocarbons,
Any inert and water-insoluble compound such as an ether compound or an ester compound may be used.

The number of times of washing with water and the amount of washing water used are repeated until the amount of water-soluble impurities in the organic liquid layer decreases to a predetermined amount.
Washing with water may be carried out in a batch system, or may be carried out in a mixer / settler system or a continuous system such as an extraction tower.

Depending on the properties of the obtained crude urethane compound, it is possible to combine a purification method such as a method of neutralizing and a method of flushing after washing with water, such as a method of flushing after washing with water.

The degree of purification is the third stage [(c)
Process] and the reaction yield.

As the urethane compound, the following various urethane compounds can be obtained corresponding to the diamine used as the raw material. 3-methoxycarbonylaminomethyl-3,
5,5-trimethyl-1-methoxycarbonylaminocyclohexane, bis (4-methoxycarbonylaminocyclohexyl) methane, 1,4 bis (methoxycarbonylamino) cyclohexane, 1,4 bis (methoxycarbonylaminomethyl) cyclohexane, 1,3 Examples thereof include bis (methoxycarbonylaminomethyl) cyclohexane.

Desorption of alcohol occurs due to thermal decomposition of these urethane compounds, which is a reaction in the third step [(c) step] described later, and isophorone diisocyanate, hydrogenated MDI, Isocyanate compounds such as cyclohexane diisocyanate and hydrogenated XDI are produced.

Next, the third step of the present invention [step (c)]
The thermal decomposition reaction, which is the above reaction, will be described in detail. It is possible to convert these urethane compounds into diisocyanate compounds in good yield by thermally decomposing them in the presence of manganese, molybdenum, tungsten, zinc as a simple substance of metal, or inorganic compounds, or organic compounds in an inert solvent under reduced pressure. I can.

By using a catalyst, a higher reaction rate can be achieved, and by carrying out the reaction in a solvent and under a reduced pressure at which the diisocyanate compound formed is distilled, the isocyanate concentration in the reaction system is kept low, It is possible to achieve a high yield by controlling the dimerization, trimerization of the isocyanate group and the following addition reaction of the urethane bond NH group and the isocyanate group.

[0080] Examples of the compound used as a catalyst include metallic manganese,
Manganese oxide (MnO or Mn ₂ O ₃ ) manganese chloride, manganese sulfate, manganese phosphate, manganese borate,
Manganese carbonate, manganese acetate, manganese naphthenate, manganese (II) acetylacetonate, manganese (III)
Acetylacetonate, metallic molybdenum, molybdenum trioxide, molybdenum acetylacetonate (MoO ₂
(acac) ₂ ) Molybdenum dioxide, metallic tungsten, tungsten hexacarbonyl, tungstic anhydride, tungstic acid, etc. can be exemplified. These can be used in the form of hydrated salt or anhydrous.

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

Manganese acetate is particularly preferable because it has sufficient activity at a low concentration in the reaction crude liquid.

The optimum amount of the catalyst used is determined according to the reactivity of the raw materials used, the temperature, and the type and amount of the catalyst. If the amount is too small, the reaction becomes slow, and if it is too large, a high boiling by-product tends to increase. Usually, the amount of the catalyst in the solvent is 0.
The most preferred range is from 0005% to 5% by weight.

If the reaction temperature is lower than 150 ° C., the generation of diisocyanate is delayed, which is not practical, and if it is higher than 300 ° C., it is difficult to carry out industrially, which is disadvantageous. That is, 150
C. to 300.degree. C. are preferred.

The solvent is required to be inactive with respect to the diisocyanate compound and the urethane compound, and can be selected from aliphatic compounds, aromatic compounds, alkylated aromatic compounds, ether compounds and the like. Even if it contains an inactive group such as a halogen group, it can be used as a solvent.

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

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

A solvent having a boiling point lower than that of the produced diisocyanate compound is distilled out together with the diisocyanate compound, which is disadvantageous because the process is complicated in practical use, and a solvent having a higher boiling point than the produced diisocyanate compound is preferable.

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

Further, since a high boiling reaction by-product accumulates in the solvent over time, a solvent having a boiling point at which regeneration can be industrially carried out is desirable.

Preferred solvents are o-ta-phenyl and m-
Terphenyl, p-terphenyl, mixed diphenylbenzene, partially hydrogenated triphenyl, dibenzylbenzene, biphenyl, phenylether, phenylcyclohexane,
Hexadecane, tetradecane, octadecane, eicosane, benzyl ether, tetramethylene sulfone and the like.

Although a suitable solvent should be selected depending on the desired diisocyanate compound, partially hydrogenated triphenyl is particularly preferable in the case of producing isophorone diisocyanate. The reaction is carried out under reduced pressure where the diisocyanate compound produced from the reaction system distills out.

This keeps the concentration of the diisocyanate compound in the system low and achieves a high reaction yield, but this effect is particularly effective when carried out under the boiling of a solvent.
From this point of view, the reaction pressure is preferably set to such a degree that the solvent is boiled at the reaction temperature. If the decompression degree is too high, it will be difficult to collect the by-produced alcohol, and it will be disadvantageous in terms of equipment and utility.
A value of 0 Torr or less is preferable. The urethane compound, which is the starting material in the reaction in the third step, may be charged in the solvent in the entire amount to be reacted from the beginning, but this is disadvantageous because the amount of solvent used is large.

In a continuous reaction, 0.0005% by weight to
The solvent containing 5% by weight of the catalyst is preferably used in an amount of 0.2 to 20 times by weight the amount of the urethane compound to be treated every hour. If it is more than 20 times by weight, the scale of the device becomes large and it is not economical.

From this point, a continuous reaction in which a solvent containing a catalyst is boiled under reduced pressure and a urethane compound is charged therein is advantageous.

When manganese acetate is used as the catalyst, manganese acetate has high solubility in methanol, which is preferable. ． The catalyst is preferably added by dissolving it in a solvent such as methanol rather than adding it in the form of solid or powder, because the amount of the catalyst is small.

Further, in order to reduce the amount of the solvent and unreacted raw materials mixed in the produced diisocyanate compound, the vapor generated from the reactor is introduced into a distillation column equipped with a reflux device, and a distillate rich in the isocyanate compound is added to the top of the column. It is particularly advantageous to carry out the purification of the diisocyanate by using a reactor having a structure as obtained in 1.

When the by-produced methanol and the diisocyanate compound are separated from each other, the condenser, which is obtained by decondensing the diisocyanate compound, is kept at a high temperature such that the methanol does not condense. The diisocyanate compound and methanol are advantageously separated and recovered by condensing with a lower temperature condenser of 2.

When separating and recovering methanol,
Instead of the second capacitor, it may be absorbed by an inert solvent.

Further, a high-boiling-point by-product is formed with time in the solvent, and this by-product causes an addition reaction with the diisocyanate group of the product diisocyanate compound, so that the yield of the diisocyanate compound is increased. descend.

As a method for preventing this, the crude liquid mixture in the reactor is continuously withdrawn and flash-evaporated to remove the high-boiling-point by-product which is the bottom of the flash evaporator, and at the same time, to evaporate the high-boiling-point solvent rich. This is performed by condensing the mixed gas of (1) and returning the mixed liquid of the condensed solvent, unreacted urethane compound, diisocyanate compound as a product, etc. to the reactor.

At this time, the catalyst is also lost together with the withdrawn high boiling point by-product, so a considerable amount is additionally charged into the reactor.

It is possible to collect and reuse the catalyst entrained in the high boiling by-products, but the catalyst used in the method of the present invention is relatively inexpensive and the amount used is small. Does not increase the cost so much.

The yield of the diisocyanate compound is remarkably improved by using not only the catalyst but also the co-catalyst in the third reaction.

Triphenyl phosphite is particularly preferred as the cocatalyst used.

INDUSTRIAL APPLICABILITY The present invention enables industrial production of a diisocyanate compound without using phosgene.

Hereinafter, the present invention will be described in more detail with reference to examples.

[Synthesis Example-1] [Synthesis of dimethyl carbonate using carbon monoxide, methanol and oxygen as raw materials] Using a Teflon coated autoclave having an internal volume of 3 liters, dimethyl carbonate was prepared. -Bonet synthesis reaction was performed.

67.5 mmol of palladium chloride as a catalyst /
47.5 vol% of nitrogen gas using 360 ml of methanol solution of liter, cuprous acetate 1687 mmol / liter and magnesium chloride 1687.5 mmol / liter.
Argon / oxygen (oxygen concentration 33.0 vol%) 22.5 vol%
The mixed gas of 1. was introduced at 12.0 kg / cm ² , the temperature inside the autoclave was raised to 130 ° C., and the reaction was carried out for 1 hour.

The reaction crude liquid was distilled to obtain dimethyl carbonate. The above synthetic reaction was repeated 25 times to obtain about 200
g of dimethyl carbonate was obtained.

The chlorine content in the obtained dimethyl carbonate was 5 ppm.

An ion chromatograph (IC-500) was used for measuring the chlorine content. [Synthesis Example-2] The synthesis reaction was repeated 15 times in the same manner as in Synthesis Example-1 except that sodium chloride was used instead of magnesium chloride to obtain about 320 g of dimethyl carbonate.

However, the reaction in this case proceeded with the catalyst suspended in the liquid.

The chlorine content in the obtained dimethyl carbonate was about 4 ppm.

[Synthesis Example 3] 158.7 g of dimethyl carbonate synthesized in Synthesis Example-1 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, into the above flask, 3.97 g of a 28% methanol solution of sodium methylate and 75 g of isophoronediamine (abbreviated as IPDA) were charged by two charging pumps at a uniform charging rate over 120 minutes. It is. During this period, the reaction temperature was kept at 70 ° C.

The chlorine content at this point was 3 ppm.

Further, after the completion of the charging, the reaction crude liquid obtained by aging at the same temperature for 3 hours and then neutralized with phosphoric acid was analyzed by gas chromatography. As a result, a urethane compound corresponding to IPDA, namely, 3- The yield of methoxycarbonylaminomethyl-35,5-trimethyl-1-methoxycarbonylaminocyclohexane (abbreviation: isophorone dicarbamate, abbreviation IPDC) based on IPDA was 98.1.
It was confirmed that it was generated in%. Aged at the same temperature for another 3 hours (total aging time 6 hours), IPDC became IPDA
It was confirmed that the yield was 99.5%.

The reaction crude liquid was subjected to a low boiling point removing treatment at 150 ° C.

The chlorine content at this point was 6 ppm.
Further, it was washed with water to obtain IPDC. The chlorine content at the time when 1.25 times the amount of water was added to the liquid after the deboiling treatment was 2 ppm.
Met. The chlorine content in IPDC obtained by the dehydration treatment was 3 ppm.

[Synthesis Example-4] The IPDC obtained in Synthesis Example-3 was continuously decomposed using a glass reboiler having a capacity of 300 ml with a 10-stage older tower set.

Dibenzyltoluene was used as the solvent.

First, 117 ml of dibenzyltoluene and 10 ppm of anhydrous manganese acetate corresponding to dibenzyltoluene were charged to the reboiler, and heated under reduced pressure of 10 Torr until boiling.

Then, 59.0% by weight of IPDC was added to the reactor,
120 g of a mixed solution of 41.0% by weight of dibenzyltoluene
It was charged at a speed of / Hr.

The product isophorone diisocyanate (abbreviation: IPDI) was withdrawn from the top of the distillation column, and operation was carried out at a bottoms withdrawing speed such that the reactor liquid level was constant.

Warm water of 60 ° C. was flown through the condenser, and I
The PDI component was condensed and the methanol was released as a gas.
During operation, the concentration of anhydrous manganese acetate in the reactor was 10 ppm
In order to maintain the temperature of the solution, 125 ppm of a solution of anhydrous manganese acetate in methanol was charged into the reaction solution according to the amount of bottoms.

When the internal temperature, the respective weights of the distillate and the bottoms, and the composition became stable, 18.2 g of the distillate was distilled in 1 hour.
77.2% by weight of PDI, monoisocyanate (abbreviation:
IPMI) 22.7% by weight, dibenzyltoluene 0.0
It was 5% by weight.

The reactor temperature was 245 ° C.

The IPDC conversion was 99% by weight, and the IPDC high boiler conversion was 6% by weight. Yield is charged IP
Based on DC, IPDI was 74% and IPMI was 19%. The chlorine content in the obtained IPDI was 0.2 ppm.

[Synthesis Example-5] Anhydrous manganese acetate was dissolved in methanol to a concentration of 1% by weight.

This solution was diluted 80-fold with IPDI and
The catalyst solution was 25 ppm.

The liquid was uniform and had a low viscosity.

Using the above catalyst solution, the urethane compound was charged in 5 stages from the bottom of the distillation column, and the operation was performed in the same manner as in Synthesis Example 4 except that the catalyst charge stage was changed from the bottom to 13 stages.

When the internal temperature, the respective weights of the distillate and the bottoms, and the composition became stable, the distillate was distilled in 1 hour.
It was 8.1% by weight, IPMI 1.8% by weight, and m-ta-phenyl 0.05% by weight.

The IPDC conversion rate was 99% by weight, and the IPDC high boiler conversion rate was 2% by weight. Yield is charged IP
Based on DC, IPDI was 95.5% and IPMI was 1.5%. The obtained IPDI fraction was further purified by batch distillation to a purity of 99.7% and used as a raw material in the following test examples.

The chlorine content in the obtained IPDI was 0.1.
It was ppm.

[Test Example-1] IP obtained in Synthesis Example-4
DI (hereinafter referred to as DMC method IPDI) is a commercially available IPD produced by the phosgene method and having a chlorine content of 245 ppm.
U together with I (hereinafter referred to as phosgene method IPDI)
V-irradiation was performed to measure the appearance and the change with time of the NCO group weight%, and the weather resistance was comparatively examined.

Using a UV lamp of 50 mW / min, each sample was placed in a heat-resistant bottle containing N ² and kept at 50 ° C. Appearance at the start of the test is APHA, DMC
The method IPDI was 10 and the phosgene method IPDI was 8.

The appearances after 1 week were 30, and 60, respectively, and the appearances after 2 weeks were 50 and 75, respectively.
The appearances after 4 weeks were 70 and 90, respectively, and the DMC method IPDI was less colored at any time point, and carbon monoxide, methanol, and oxygen were used as raw materials in the DMC method I.
It was found that PDI was superior to phosgene IPDI. The NCO group weight% was a theoretical amount in any measurement, and no change was observed.

[Test Example-2] DMC Method I using carbon monoxide, methanol and oxygen obtained in Synthesis Example-5 as starting materials
PDI was kept at 50 ° C. in a separate container together with phosgene-method IPDI, and the appearance and the change with time of NCO group weight% were comparatively measured, and the heat resistance was comparatively examined.

Each of the samples was put in a heat-resistant bottle containing N ₂ and stored in an oven kept at 50 ° C.

The appearance at the start of the test is APHA, DM
The C method IPDI was 10, and the phosgene method IPDI was 8.

The appearance after 3 months is 20 and 8 respectively.
0, DMC method IPDI has little coloring, and DMC method IPDI
It was found that DI was superior to the phosgene method IPDI. The NCO group weight% was a theoretical amount in any measurement, and no change was observed.

[Comparative Synthesis Example-1] The procedure of Synthesis Example-3 was repeated except that a commercially available phosgene-process dimethyl carbonate [chlorine content was about 1000 ppm] was used.

In Synthesis Example-3, the yield of IPDC relative to IPDA after aging time of 6 hours was 99.5%, whereas in Comparative Synthesis Example-1 the yield of IPDC relative to IPDA was
It was 95.5%.

The chlorine content at the time of charging the starting materials was 670 ppm, the chlorine content at the time of performing the deboiling treatment was 1260 ppm, and the chlorine content at the time of adding 1.25 times the amount of water was 560 ppm. The chlorine content in IPDC obtained by the dehydration treatment was 750 ppm.

A thermal decomposition reaction of IPDC was carried out in the same manner as in Synthesis Example-4.

The IPDC conversion was 98.5% by weight, and the IPDC high boiler conversion was 7% by weight. The chlorine content in the obtained IPDI was 355 ppm.

[Measurement of Total Chlorine Content] IPDI was measured by phosgene method IPDI together with total chlorine content according to ASTM D
It measured based on the method of -1638. On the other hand, the total chlorine content of the commercially available phosgene-method IPDI was 245 ppm.

[0150]

As is apparent from the comparative example and FIG. 1, in the case of DMC synthesized by the phosgene method, the chlorine content at the time when the starting materials were charged was as close as possible to the value of Sus 304. Becomes

On the other hand, Synthesis Example-1 and Synthesis Example-2
It is clear that the material consisting of Sus 304 can be used without problems when using the DMC obtained in 1.

In addition, the chlorine content at the time of performing the deboiling treatment is shown in FIG. 1 and the examples and comparative examples, and the chlorine content at the time of charging the starting materials shows that of DMC synthesized by the phosgene method. In this case, the material made of Sus 304 cannot be used, whereas the DM obtained in Synthesis Example-1 and Synthesis Example-2
It is clear that the material consisting of Sus 304 can be used without problems when C is used.

Furthermore, in the chlorine content at the time when 1.25 times the amount of water was added, from the results shown in FIG. 2 and Examples and Comparative Examples, in the case of DMC synthesized by the phosgene method, Sus 304, Sus 31
Synthetic example-1
And when using the DMC obtained in Synthesis Example-2,
It is clear that any material consisting of s 304, Sus 316 can be used without problems.

That is, from the above results, the dimethyl carmine of the present invention containing carbon monoxide, methanol and oxygen as raw materials is used.
In the method in which the starting material is bonnet, the superiority of the yield in the process of synthesizing the urethane compound is particularly clear.

Regarding the chlorine concentration, there is a significant difference between the production method of the present invention and the conventional method in each step. This indicates that the conventional method requires a corrosion resistant material in each step.

It is well known that a high chlorine content causes severe corrosion of metal materials with which it comes into contact.

Further, the diisocyanate compound produced by the method of the present invention having a low chlorine content is used, and the polyurethane produced using the diisocyanate compound is superior in weather resistance, corrosion resistance and
It is clear that heat resistance is obtained.

The present invention also includes the following preferred embodiments.

(1) The method for producing a diisocyanate compound according to claim 1, wherein the diamine in step (b) is an aliphatic diamine.

(2) The method for producing a diisocyanate compound according to claim 1, wherein the aliphatic diamine in step (b) is a cyclic diamine.

(3) The method for producing a diisocyanate compound according to claim 1, wherein the diamine in step (b) is isophoronediamine.

(4) The method for producing a diisocyanate compound according to claim 1, wherein the alkali catalyst in step (b) is sodium methylate.

(5) The method for producing a diisocyanate compound according to claim 1, wherein sodium methylate which is the catalyst in step (b) is added continuously or intermittently.

(6) The method for producing a diisocyanate compound according to claim 1, wherein the charged molar ratio of dimethyl carbonate / diamine in step (b) is 2 to 50.

(7) The method for producing a diisocyanate compound according to claim 1, wherein the water content in dimethyl carbonate used in step (b) is less than 0.2%.

(8) The process for producing a diisocyanate compound according to claim 1, wherein the crude urethane compound liquid which is the product of step (b) is neutralized with phosphoric acid.

(9) The process for producing a diisocyanate compound according to claim 1, wherein the urethane compound crude liquid which is the product of the step (b) is neutralized with phosphoric acid and then washed with water.

(10) The process for producing a diisocyanate compound according to claim 1, wherein the crude urethane compound liquid which is the product of step (b) is neutralized with phosphoric acid and then flash-evaporated.

(11) The method for producing a diisocyanate compound according to claim 1, wherein the water content of the diamine used in step (b) is less than 1%, and the crude urethane solution which is the product of step (12) step (b) is treated with benzene. /
The method for producing a diisocyanate compound according to claim 1, which is washed with an aqueous system.

(13) The method for producing a diisocyanated compound according to claim 1, wherein the crude urethane liquid which is the product of step (b) is washed with a benzene / water system, and then the urethane compound is melted and purified by distillation.

(14) The method for producing a diisocyanate compound according to claim 1, wherein the by-product methanol in the thermal decomposition step which is the step (c) is removed by a vacuum line of less than 50 Torr. (15) The method for producing a diisocyanate compound according to claim 1, wherein the high boiling point solvent in the step (c) is partially hydrogenated triphenyl.

(16) The method for producing a diisocyanate compound according to claim 1, wherein the catalyst in step (c) is manganese acetate.

(17) The method for producing a diisocyanate compound according to claim 1, wherein the catalyst in step (c) is one of manganese sulfate, manganese chloride and manganese naphthenate. (18) The method for producing a diisocyanate compound according to claim 1, wherein the catalyst in step (c) is zinc bromide.

(19) The method for producing a diisocyanate compound according to claim 1, wherein the catalyst in step (c) is continuously added as a methanol solution. (Below margin)

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a chlorine concentration and a temperature at which various materials can be used (stress corrosion cracking limit line) (Corrosion and Corrosion Protection Association edition / Handbook of Corrosion Engineering / Published by Nikkan Kogyo Shimbun, p. )
Is.

[Fig. 2] Fig. 2 [Chemical Industry Co., Ltd.-Secondary usage record and life analysis-p. [78] is a diagram showing how many temperatures the material made of Sus 304 (with and without welds) can withstand each chlorine concentration region.

[Explanation of symbols]

None (the margin below)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C07C 263/04 271/08 7188-4H // C07B 61/00 300

Claims (1)

[Claims] 1. The following three steps (a) a step of reacting carbon monoxide, oxygen and methanol to obtain dimethyl carbonate (b) the dimethyl carbonate in the presence of an alkali catalyst: A step of reacting with a diamine to obtain a urethane compound (c) a step of thermally decomposing the urethane compound under reduced pressure of 1 to 700 Torr in the presence of a catalyst to obtain a diisocyanate compound, the method for producing a diisocyanate compound.