JPH0460104B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a triisocyanate compound having three isocyanate groups in one molecule that are not directly bonded to an aromatic ring.

[Conventional technology]

It has been known that polyisocyanates in which isocyanate groups are not directly bonded to aromatic rings can be used as raw materials for producing non-yellowing polyurethane resins with excellent weather resistance. Representative products of these non-yellowing polyisocyanates include hexamethylene diisocyanate, 2,2,4- or 2,2,4-
- trimethylhexamethylene diisocyanate,
Examples include isophorone diisocyanate, 1,4-diisocyanatocyclohexane, bis(incyanatomethyl)cyclohexane, and xylylene diisocyanate, but these have a pungent odor at room temperature and are toxic to humans, so they must be handled safely. There are some serious drawbacks. Further, since diisocyanates are difunctional, when used as a crosslinking agent for polyurethane resins, the crosslinking density is often too low.
Therefore, these diisocyanates are derived by reacting with so-called adducting agents such as triols such as trimethylolpropane, water, and tertiary-butanol, to make them polymeric and polyfunctional, and are used as adducts. There is. However, since these are polymer mixtures, they have a high viscosity and require dilution with a solvent for handling, and their isocyanate group content is inevitably reduced.

Against this background, in recent years, efforts have been made to develop non-yellowing trifunctional isocyanate compounds that have extremely low viscosity because they are monomers, and are less irritating and less toxic due to their extremely low vapor pressure at room temperature. is being carried out. These triisocyanates are, for example, JP-A-55-327, JP-A-55-167269, JP-A-56-
61341, JP-A No. 56-127341, etc., all are produced by the reaction of the corresponding triamino compound with phosgene (phosgenation reaction). Generally, the phosgenation reaction of amines is carried out by the hydrochloride method in which the hydrochloride of the amine is reacted with phosgene in an inert solvent at 60 to 230°C to form an isocyanate, or the amine is reacted at 40°C or lower, preferably 8°C or lower. There are two cold-thermal two-step methods in which a mixture of monocarbamyl chloride and amine hydrochloride is obtained by reacting with phosgene, and then heated to 60 to 230°C under phosgene blowing to obtain an isocyanate. However, although the former hydrochloride method has the advantage of being able to obtain isocyanate in a relatively high yield in the laboratory, it requires the synthesis and purification of an intermediate called amine hydrochloride, and this amine hydrochloride is usually It has many disadvantages in industrial processes, such as the fact that it is a solid and its handling is complicated. Therefore, in the case of isocyanate production by the phosgenation reaction of amines, industrially, it is common to give priority to the advantages in terms of process and equipment and adopt a two-step cold/hot process. In fact, diisocyanates such as those exemplified above are normally produced and supplied industrially by a two-step cold/hot process without any problems.

However, when converting a triamino compound (hereinafter simply referred to as triamine), which has three primary amino groups in one molecule that are not directly bonded to an aromatic ring, with phosgene to convert it into triisocyanate, the above-mentioned cold and hot two-step method is used. 60 if you are trying to hire
The slurry-like solid produced by the cold phosgenation reaction at a temperature above ℃ starts to aggregate and eventually becomes lumpy, so the reaction does not proceed smoothly, and even if the reaction is continued forcibly and completed, it will result in a tar-like high-temperature product. The problem encountered is that the yield of triisocyanate, which is important, cannot be increased because the amount of molecular substances and insoluble solids produced increases. Another drawback is that the triisocyanate produced by such a reaction contains many impurities. Examples of impurities include those in which one of the three isocyanates is replaced with chlorine, and so-called hydrolyzable chlorine. Triisocyanate, which has a high content of hydrolyzable chlorine, is usually used because polyurethane resin produced using it has drawbacks in weather resistance.
It is preferably 500 ppm or less.

Such difficulties peculiar to the phosgenation reaction of triamines can be solved to some extent by using the chlorine salt method or the so-called carbamate method as described in JP-A-52-122348.

However, the hydrochloride method has major problems in terms of equipment and process as described above, and the carbamate method also requires a gas component other than phosgene called carbon dioxide, which complicates the equipment.
It has drawbacks such as requiring heat and multiple steps, and also requiring a relatively long time to complete the reaction.

In addition, as a measure to avoid agglomeration of the reaction contents in such a phosgenation reaction of triamine, it has been proposed to conduct the reaction in a reactor made of a water-repellent material at least in the low-temperature reaction section. (Unexamined Japanese Patent Publication No. 57-123158)
However, the use of such a special reactor has many problems in terms of complication and high cost of the equipment.

[Problem that the invention seeks to solve]

In other words, when producing triisocyanate through the phosgenation reaction of triamine, a two-stage cold and hot process, which is easy to adopt industrially, avoids agglomeration of solids and achieves high yield and high purity, and is limited to special reactor materials. Developing a technology that can produce products with high productivity without causing damage has been an attractive challenge for this industry.

[Means and actions for solving problems]

As a result of intensive research to achieve the above-mentioned problems in the phosgenation reaction of triamine, the present inventors surprisingly found that by carrying out the phosgenation reaction of triamine in the coexistence of hexamethylene diamine, They discovered that all the problems could be solved and completed the present invention.

That is, in the present invention, when producing a corresponding triisocyanate compound by reacting a triamino compound having three primary amino groups in one molecule that are not directly bonded to an aromatic ring with phosgene, the triamino compound and hexane are reacted. The present invention provides a manufacturing method characterized by reacting a mixture of methylene diamine with phosgene.

According to the method of the present invention, the cold-thermal two-step phosgenation reaction of triamine proceeds as a uniform white slurry without agglomeration in any reactor material or temperature range. , which eventually transforms into a homogeneous clear solution within a relatively short time. Furthermore, the yield of the final product, triisocyanate, is much higher than in the case where hexamethylene diamine is not present, and a highly purified product is obtained. Furthermore, the yield of hexamethylene diisocyanate produced at the same time is sufficiently high, making it an extremely excellent process as an industrial method for producing triisocyanate.

There is a prior art related to the phosgenation reaction of a mixture of two or more amines (Kaisei 48-48419), but
This technique is aimed at the economical advantage of avoiding duplication of equipment, and does not mention anything about the phosgenation reaction of triamino compounds.

Triamino compounds having three primary amino groups in one molecule that are not directly bonded to an aromatic ring and used as raw materials of the present invention include, for example, 1,8-diamino-4-aminomethyloctane, 1,6, 11−
Triaminoundecane, 1,2,3-triaminopropane, 1,3,5-tris(aminomethyl)
Benzene, 1,3,5-tris(aminomethyl)
Cyclohexane, 2-aminomethyl-3-(3-
(aminopropyl)-5-aminomethyl-bicyclo-[2,2,1]-heptane, 2-aminomethyl-
3-(3-aminopropyl)-6-aminomethyl-
Bicyclo-[2,2,1]-heptane, 1,4-
(or 1,3-)bis(aminomethyl)-2-
(3-aminopropyl)-cyclohexane, 1,4
-(or 1,3-)bis-(aminomethyl)-1
-(3-aminopropyl)-cyclohexane, 1-
Aminomethyl-2-(3-aminopropyl)-4
(or 5)-(2-aminoethyl)-cyclohexane and the like.

These triamines are mixed with hexamethylene diamine and subjected to the phosgenation reaction, but the mixing ratio is (triamine): (hexamethylene diamine)
The weight ratio is preferably 5:95 to 90:10. If the amount of triamine is too small, it will be difficult to separate the triisocyanate compound after the reaction, and if the amount of hexamethylenediamine is too small, the agglomeration of the reaction contents will be insufficiently suppressed, both of which are undesirable.

Hereinafter, the method of the present invention will be explained in order of steps.

In the low-temperature phosgenation step, which is the first step of the method of the present invention, a mixture of triamine and hexamethylene diamine is usually prepared in the presence of an inert solvent at a relatively low temperature (usually below 60°C, preferably -10 to 10°C).
℃). The amount of phosgene used is at least equimolar, usually at least twice the mole relative to the amino group.
As the inert solvent, tetralin, decalin, chlorobenzene, 0-dichlorobenzene, trichlorobenzene, etc. are commonly used because they are inert to phosgene and isocyanate groups and have a relatively high boiling point. The low-temperature phosgenation step usually requires 1 to complete the reaction, depending on the reaction temperature.
It takes between 6 hours and 6 hours.

Next, the temperature of this low-temperature phosgenation reaction product is raised in order to transfer it to a high-temperature phosgenation reaction. In the conventional phosgenation reaction of triamine using a cold two-step method, the contents agglomerate at this stage of temperature rise, making it impossible to stir the system, but according to the method of the present invention, such agglomeration does not occur at all. No, the system remains a homogeneous slurry.

The high-temperature phosgenation reaction is usually carried out at a temperature of 100 to 230°C while supplying phosgene into the system, during which the carbamyl chloride produced in the low-temperature phosgenation step is thermally decomposed and converted into isocyanate. When the reaction is completed, the system becomes a homogeneous transparent liquid, and according to the method of the present invention, the time required for the high-temperature phosgenation step to complete the reaction is usually 1 to 15 hours, depending on the heating temperature.

The above reaction process is applicable to both a batch method and a continuous reaction method.

After the reaction is completed, the remaining phosgene in the system is purged with an inert gas such as nitrogen, the solvent is recovered, and the products triisocyanate and hexamethylene diisocyanate are separated by an appropriate method. As a separation method, vacuum distillation using the difference in boiling point between triisocyanate and hexamethylene diisocyanate is preferred.

The triisocyanate and hexamethylene diisocyanate thus obtained are each effectively used as an isocyanate component to be a raw material for, for example, polyurethane resin.

Hereinafter, the content of the present invention will be explained more specifically using Examples.

Example 1 400 g of orthodichlorobenzene was charged into a glass reactor equipped with a stirrer, a thermometer, a condenser, and a gas blowing tube, and after cooling to 0°C, phosgene 515 was added.
g was introduced and dissolved. 50 g of 1,8-diamino-4-aminomethyloctane and 50 g of hexamethylene diamine dissolved in 600 g of orthodichlorobenzene were added dropwise into this mixture under stirring over 2 hours while maintaining the reactor internal temperature below 5°C. After the dropwise addition was completed, stirring was continued for an additional hour. The system became a highly fluid white slurry. Thereafter, the temperature was raised to 140°C over about 1 hour while blowing phosgene, and the temperature was maintained at 140°C, and phosgene was continued to be supplied for 5 hours. During this time, the reaction system maintained a highly fluid slurry state, and finally became a yellow transparent liquid with no residual solid matter observed. After blowing nitrogen gas into the reaction solution to remove residual phosgene, the solvent ortho-dichlorobenzene was distilled off under reduced pressure, and a small amount (90%
g) The tar content was removed.

The obtained isocyanate mixture was rectified under reduced pressure to obtain 70 g (yield 96%) of hexamethylene diisocyanate as a fraction with a boiling point of 126°C/10 mmHg and a boiling point of 126°C/10 mmHg.
62 g (yield: 85%) of 1,8-diisocyanato-4-isocyanatomethyloctane was obtained as a fraction at 193°C/3 mmHg. The purity of the obtained hexamethylene diisocyanate as determined by gas chromatography analysis (hereinafter referred to as GC purity) was 99% or higher, the hydrolyzable chlorine content was 150 ppm, and 1,8-diisocyanate.
The GC purity of 4-isocyanimethyloctane is 98
% (low-boiling impurities 2%), hydrolyzable chlorine content is
It was 380ppm.

Example 2 The reaction was carried out in the same manner as in Example 1 except that 1,8-diamino-4-aminomethyloctane was used as 75 g and hexamethylene diamine was used as 25 g. As in Example 1, the reaction system maintained a highly fluid slurry state over the entire temperature range, and finally became a transparent yellow body. Purification was carried out in the same manner as in Example 1, and 35
g of hexamethylene diisocyanate (yield 96
%) and 90 g of 1,8-diisocyanato-4-isocyanatomethyloctane (yield 83%). GC purity of hexamethylene diisocyanate is 99%
Above, the hydrolyzable chlorine content is 140ppm, 1.8
-Diisocyanato-4-isocyanatomethyloctane has a GC purity of 97% and a hydrolyzable chlorine content of
It was 450ppm.

Example 3 The reaction was carried out in the same manner as in Example 1, except that 25 g of 1,8-diamino-4-aminomethyloctane and 75 g of hexamethylene diamine were used. As in Example 1, the reaction system remained in a highly fluid slurry state over the entire temperature range, and was maintained at 140°C for 3 hours.
After a few minutes had elapsed, the solid matter disappeared and a pale yellow transparent liquid was formed. Purification was carried out in the same manner as in Example 1 to obtain 105 g of hexamethylene diisocyanate (yield 97%). 32.5 g of 1,8-diisocyanato-4-isocyanatomethyloctane (yield 90%) was obtained.
GC of the obtained hexamethylene diisocyanate
Purity is over 99%, hydrolyzable chlorine content is
The GC purity of 180 ppm, 1,8-diisocyanato-4-isocyanatomethyloctane was 98.5%, and the hydrolyzable chlorine content was 290 ppm.

Comparative Example 1 400 g of orthodichlorobenzene was charged into the same reactor as in Example 1, cooled to 0°C, and then 260 g of phosgene was added.
g was introduced and dissolved. Into this, 50 g of 1,8-diamino-4-aminomethyloctane dissolved in 600 g of orthodichlorobenzene was added to the reactor at a temperature of 5.
Dropwise while stirring for 2 hours while keeping the temperature below ℃.
After the dropwise addition was completed, stirring was continued for an additional hour. The system was in a highly viscous slurry state. After that, the temperature was raised while blowing phosgene, and when the reaction solution reached about 70°C, the slurry-like solids began to coagulate, and the sticky solids got entangled in the stirring device, and finally turned into lumps. Stirring became impossible. The temperature continued to rise while stirring was stopped, and when the reaction liquid temperature reached approximately 130°C, the lumps began to loosen, so stirring was restarted and the solids were broken off with shear force.
The supply of phosgene was continued for 8 hours at 145°C. The resulting liquid was blackish brown and some solid suspended matter remained.

After removing residual phosgene with nitrogen, orthodichlorobenzene was removed under reduced pressure. The obtained concentrate was treated in a thin film evaporator and separated into 31 g of black tar and pale yellow distilled isocyanate. The distillate was rectified under reduced pressure to obtain 38 g (yield 52%) of 1,8-diisocyanato-4-isocyanatomethyloctane. The GC purity of this product is 93% (low boiling impurity 7
%), and the hydrolyzable chlorine content was 2000 ppm.

Example 4 Monochlorobenzene was added to a reactor similar to Example 1.
After charging 400 g and cooling to 0°C, 480 g of phosgene was introduced and dissolved. Into this was dissolved 600 g of monochlorobenzene. 1,6,11-triaminoundecane 50g and hexamethylene diamine 50g
g was added dropwise over 2 hours with stirring while keeping the internal temperature of the reactor below 5°C, and after the addition was completed, stirring was continued for an additional hour. The system was a slightly yellow slurry with fluidity. Thereafter, the temperature was raised to the solvent reflux temperature over about 1 hour while blowing phosgene, and the reaction was continued for 7.5 hours under the solvent reflux condition. During this time, the reaction system maintained a highly fluid slurry state and finally became a light brown transparent liquid. The same purification procedure as in Example 1 was performed to obtain 69 g of hexamethylene diisocyanate (yield 95%) and 58 g of 1,6,11-triisocyanatoundecane as a fraction with a boiling point of 208°C/2 mmHg.
g (yield 84%) was obtained.

of the obtained hexamethylene diisocyanate
GC purity is over 99%, hydrolyzable chlorine content is
The GC purity of 1,6,11-triisocyanatoundecane was 97%, and the hydrolyzable chlorine content was 440 ppm.

Comparative Example 2 A reaction was carried out in exactly the same manner as in Example 4 except that the amount of phosgene was 220 g and hexamethylene diamine as an amine component was not added.
When the temperature reached 70°C, the solid content in the contents began to aggregate and form lumps. After stopping stirring and raising the temperature to the reflux temperature of the solvent, stirring was restarted, but although the lumps were loosened to some extent, they were not dispersed. The reaction was continued for 10 hours while the solvent was refluxed and phosgene was blown in, but a large amount of solid matter remained. 1, 6, 11 obtained by the same purification procedure as in Example 4
- The yield of triisocyanatoundecane was only 22%.

Claims (1)

[Scope of Claims] 1. When producing a corresponding triisocyanate compound by reacting a triamino compound having three primary amino groups in one molecule that are not directly bonded to an aromatic ring with phosgene, the triamino compound A manufacturing method characterized by reacting a mixture of and hexamethylene diamine with phosgene. 2 The triamino compound is 1,8-diamino-4-
Claim 1 which is aminomethyloctane
The method described in section. 3. The method according to claim 1, wherein the weight ratio of hexamethylene diamine to triamino compound is 5:95 to 90:10.