JPH0812642A - Production of urethanediol - Google Patents

Abstract

PURPOSE:To safely and quickly obtain the colorless high grade urethanediol in a simple operation and in a high yield by reacting an aliphatic diamine with a cyclic alkylene carbonate in a water solvent. CONSTITUTION:The urethanediol is obtained by reacting an aliphatic diamine (e.g. hexamethylenediamine) with a cyclic alkylene carbonate (e.g. ethylene carbonate) in water solvent by a continuous flow style using a tubular reactor at 40-100 deg.C: for 1-3hr. Water is used in an amount of 0.2-2 times that of the aliphatic diamine. The urethanediol itself is useful as a raw material for polyurethanes, but the urethanediol is thermally converted into an isocyanate which is useful for coatings, adhesives, various binders, etc., as a blocked isocyanate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a urethane diol by reacting an aliphatic diamine with a cyclic alkylene carbonate. Urethane diol is a useful compound that can be used as a block isocyanate in paints, adhesives, various binders, etc. because it is a raw material for polyurethane and is converted into isocyanate by heating.

[0002]

It is known that urethane glycols can be obtained in quantitative yields by the reaction of aliphatic diamines with cyclic alkylene carbonates.

[0003] However, this reaction is a reaction accompanied by intense heat generation, and if the reaction temperature becomes too high, the product may be colored or polymerized, and it may cause a danger. For example, in Japanese Patent Application Laid-Open No. 2-151618 and US Pat. No. 5,001,21, the reaction of hexamethylenediamine and ethylene carbonate generates a very large amount of heat, and the temperature of the mixture rises to 170 ° C. The object is said to have been reddish brown.

In order to avoid such a situation, normally, Japanese Patent Laid-Open No. 57-82360 and Japanese Patent Laid-Open No. 2-22241 are used.
As described in Japanese Patent Publication No. 8 or the like, a measure is taken in which one of the raw materials is successively dropped and the reaction is gradually advanced to suppress rapid heat generation. However, such countermeasures against heat generation only on the operation side require complicated operation management and auxiliary equipment in actual industrial scale production, and there are also safety concerns.

Further, when the cyclic alkylene carbonate is solid and the raw material aliphatic diamine is also solid, it is necessary to grind or melt the raw material when charging the raw material. Moreover, since it requires heating as much as the melting point temperature of the raw materials from the initial stage of the reaction, and when the raw materials are mixed in a short time, a rapid heat is generated,
One is forced to gradually add one ingredient. Further, as the reaction progresses, the mixture thickens and sometimes solidifies to make it difficult to remove heat and stir, or it may take a lot of labor to take out the product.

Therefore, it cannot be said that the prior art is a simple, safe and industrially satisfactory method.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and to react an aliphatic diamine and a cyclic alkylene carbonate under mild reaction conditions to obtain an uncolored high-grade urethane diol simply and easily. It is an object of the present invention to provide a method for safely producing a high yield in a short time.

[0008]

Means for Solving the Problems As a result of earnest research on a method for producing a urethane glycol by reacting an aliphatic diamine and a cyclic alkylene carbonate, the present inventors have found that both raw materials can be produced by using water as a reaction solvent. It was found that the reaction temperature can be easily controlled even when mixed for a short period of time, the charging of raw materials and the taking out of the product are facilitated, and a high-quality uncolored urethane glycol can be produced in a short time with a quantitative yield. Furthermore, it has been found that a continuous flow reaction using a tubular reactor becomes possible, and a simpler production method of urethane glycol with higher productivity can be realized. The present invention has been completed based on the above findings.

That is, the present invention is a method for producing a urethane diol, which comprises reacting an aliphatic diamine and a cyclic alkylene carbonate with water as a solvent.

The present invention will be described in detail below.

Examples of the aliphatic diamine used in the method of the present invention include straight-chain and branched-chain fatty acids such as ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, diaminobutane, diaminopentane and hexamethylenediamine. Group alkyldiamines; alicyclic diamines such as isophoronediamine and 1,4-cyclohexyldiamine; and cycloaliphatic diamines such as piperazine, but are not limited thereto. Further, as the cyclic alkylene carbonate, ethylene carbonate,
Propylene carbonate or the like is used.

One or both of these reaction raw materials may be charged into the reactor as an aqueous solution. Normally, both raw materials are charged into the reactor at the same time, but either one or both may be added sequentially.
It is also possible to continuously produce urethane diol while continuously supplying both raw material aqueous solutions to an empty column or a tubular reactor filled with a heat transfer promoting filler (glass beads, spherical silica, stainless wire mesh, etc.). .

The ratio of the aliphatic diamine to the cyclic alkylene carbonate to be used in the reaction is usually sufficient if the molar ratio of the cyclic alkylene carbonate to the aliphatic diamine is 2 times, but it is also possible to use the cyclic alkylene carbonate in an amount of 2 times by mol or more. Absent.

The amount of water used as a solvent is preferably 0.2 to 2 times the amount of the raw material aliphatic diamine. If the amount is smaller than this range, the dissolution of the aliphatic diamine becomes insufficient, the operability of the reaction is deteriorated, and the reaction temperature is rapidly increased, which is not preferable.

The reaction temperature is preferably 40 ° C. to 100 ° C. in that a non-colored high-quality urethane diol can be obtained in a quantitative yield. When the amount of water used is small and the temperature rise due to heat generation is fast, it is advisable to keep the temperature below 100 ° C. by condensing water vapor in the cooling tower and refluxing without heating the reactor.

It is also effective to use a tubular reactor to remove heat quickly. When the amount of water used is sufficient and the temperature of the reaction solution is 40 ° C or lower, the temperature is raised to 40 ° C or higher by heating.

The reaction pressure is usually atmospheric pressure, but it may be reduced pressure if necessary.

A reaction time of 1 to 3 hours is sufficient. Usually, the reaction is completed within 1 hour, and urethane glycol is quantitatively produced. If the reaction is not completed, the reaction is completed by further aging for 1 to 2 hours.

After completion of the reaction, urethane glycol may be taken out from the reaction solution in an aqueous solution state and the water may be removed by a conventional method immediately before using it for the next application, or the water may be distilled off under reduced pressure in the reactor. After that, the product may be taken out.

[0020]

EFFECTS OF THE INVENTION According to the method of the present invention, the reaction between an aliphatic diamine and a cyclic alkylene carbonate can be safely carried out under a mild reaction condition by a simple operation and a high quality of no coloring in a short time can be obtained. Urethane diol can be quantitatively produced.

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A flask having a capacity of 500 ml was charged with a solution of hexamethylenediamine (1 mol; 116 g) dissolved in 23.2 g of water, and then ethylene carbonate (2 mol; 18 g).
0 g) was added and the mixture was stirred at room temperature.

When the liquid temperature exceeds the peak (about 100 ° C.), 8
When it reached 0 ° C., it was immersed in a hot water bath, and stirring was continued at 80 ° C. for 1 hour. The reaction solution was colorless and transparent, and when it was allowed to cool to room temperature, white solid was precipitated.

The liquid after the reaction was analyzed by liquid chromatography, and it was confirmed that bis (β-hydroxyethyl) hexamethylenecarbamate was quantitatively produced.

Example 2 Hexamethylenediamine (1 mol; 116 g) was added to water 2
In a liquid dissolved in 32 g, ethylene carbonate (2mo
1; 180 g) was added and the reaction was carried out in the same manner as in Example 1. The liquid temperature peak at room temperature was about 50 ° C.
After further stirring at 50 ° C. for 1 hour, the reaction solution was analyzed by liquid chromatography to find that bis (β-hydroxyethyl) hexamethylenecarbamate was quantitatively produced. No coloration of the reaction product was observed.

Example 3 A flask having a volume of 1 L was charged with hexamethylenediamine (2 m).
ol; 232 g) dissolved in 232 g of water,
Next, ethylene carbonate (4 mol; 360 g) was added, and the mixture was stirred at room temperature. When the liquid temperature exceeds the peak (about 70 ° C) and reaches 60 ° C, dip it in a hot water bath at 60 ° C for 1 hour.
Continued stirring for hours. When the liquid after the reaction was analyzed by liquid chromatography, bis (β-hydroxyethyl) hexamethylenecarbamate was quantitatively produced. No coloration of the reaction product was observed.

Comparative Example 1 Hexamethylenediamine (1 mol; 11
6 g) and ethylene carbonate (2 mol; 180
g) was melted at 40 ° C. and stirred. Immediate heat was suddenly generated, and the liquid temperature rose to about 170 ° C. After stirring for 1 hour, the product was colored in a light red color, and the analysis by liquid chromatography showed that the yield of bis (β-hydroxyethyl) hexamethylene carbamate was 45 mol%. A by-product had formed.

Example 4 Isophoronediamine (1 mol; 170 g) was added to water 170
g of ethylene carbonate (2 mol;
180 g) was added and the reaction was carried out in the same manner as in Example 1. The liquid temperature at room temperature was 60% past the peak (about 70 ℃).
Stirring was continued at ℃ for 1 hour. The reaction solution was colorless and transparent. This was dissolved in water and analyzed by liquid chromatography, and it was confirmed that bis (β-hydroxyethyl) isophorone carbamate was quantitatively produced. No coloration of the reaction product was observed.

Comparative Example 2 Isophoronediamine (1 mol;
170 g) and ethylene carbonate (2 mol; 180
g) was stirred at 40 ° C. Exotherm started at the same time as mixing, and the liquid temperature rose to about 160 ° C. When stirring was further continued, the viscosity gradually increased, and stirring became impossible after about 1 hour.
The reaction liquid at this time was colored yellow, and the analysis by liquid chromatography showed that the yield of bis (β-hydroxyethyl) isophorone carbamate was 70 mol%, and several other by-products were formed. Was there.

Example 5 A stainless type reaction tube having an inner diameter of 10 mm and a length of 200 mm was
10 ml of a glass ball having a diameter of 2 mm was filled, and the glass ball was stood up in a water bath at 60 ° C and immersed. From the lower part of the reaction tube, an aqueous solution of hexamethylenediamine (concentration 80% by weight) and an aqueous solution of ethylene carbonate (concentration 80% by weight) were respectively supplied at a rate of 5.8 g and 9.0 g per hour.

The maximum temperature in the reaction tube was 52 ° C. The reaction tube outlet liquid is colorless and transparent, and quantitatively analyzed by liquid chromatography to give bis (β-hydroxyethyl)
It was confirmed that hexamethylene carbamate was produced.

Claims (4)

[Claims] 1. A method for producing a urethane diol, which comprises reacting an aliphatic diamine with a cyclic alkylene carbonate using water as a solvent. 2. The method for producing a urethane diol according to claim 1, wherein 0.2 to 2 times the weight of water is used relative to the aliphatic diamine. 3. The method for producing a urethane diol according to claim 1, wherein the reaction is carried out in the range of 40 ° C. to 100 ° C. 4. The reaction according to any one of claims 1 to 3, wherein the reaction is carried out in a continuous flow system using a tubular reactor.
The method for producing the urethane diol according to the item 1.