JPH0678306B2 - Method for producing acrylonitrile solution of maleimides - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an acrylonitrile solution of maleimides. More specifically, the present invention relates to a method for producing maleimides as a solution of acrylonitrile during transportation or storage.

Maleimides are useful compounds as raw materials for resins, pharmaceuticals, agricultural chemicals and the like, but the present invention provides a method for producing an acrylonitrile solution of maleimides which is easy to handle, safe and simple.

[Prior Art] Conventionally, maleimides that are solid at room temperature are generally handled in the form of powder, flakes, tablets, or the like. However, the maleimides in such a form contain fine powders of maleimides.

In particular, during the transportation of such solid maleimides, the maleimides are pulverized, and a large amount of fine powder of maleimides is generated.

Maleimides themselves are irritating to the human body, and in particular, inhaling fine powder has an unfavorable property such as irritation of nasal cavity and throat, coughing and sneezing, and irritation when left on skin. ing. Therefore, when handling maleimides containing such fine powders, it is necessary to take utmost care to make contact with the skin as much as possible.

Therefore, great effort is required to prevent generation of fine powder as much as possible during the transportation of the maleimides, and to remove the fine powders from the maleimides after the transportation.

Usually, solid materials are often transported by filling paper bags, plastic bags, drums, containers, and the like with solid materials. In these cases, contact between the solid substance and the human body is unavoidable, and it is inevitable that the solid substance or its fine powder adheres to the human body.

On the other hand, pipe transfer of solid substances may be adopted to prevent contact with the human body, but the method is technically difficult, and it is possible to stabilize these solid substances by, for example, blocking the inside of the pipe during pipe transfer. In order to transfer to, the shape, size and specific gravity of solids are severely restricted.

Therefore, it must be said that there are a number of difficult problems in the transportation or transfer method of maleimides that are solid at room temperature and must avoid contact with the human body. The same applies to the storage method.

Therefore, JP-A-62-126167 discloses a method in which maleimides are not handled as a solid, that is, transferred, transported or stored as a solution of acrylonitrile.

It can be said that this method is an excellent method in that it can solve the above-mentioned problems in handling maleimides.

As a method for producing an acrylonitrile solution of the maleimides, a tank having a heating coil or a heating outer shell and a stirrer is filled with acrylonitrile in advance, and the form of flakes, granules, powder, etc. is formed therein. There is a method in which the solid maleimides having the above are added, and thereafter, heating is performed using a heating coil, a heating outer jacket, etc. to completely dissolve the maleimides.

[Problems to be Solved by the Invention] As described above, solid maleimides have various forms such as flakes, tablets, granules and powders. In any of these forms, solid maleimides The particles themselves have the property of coming into contact with each other during storage to form extremely hard lumps.

Such solid maleimides are usually stored in paper bags, plastic bags, drums, containers, etc., but during storage, they become large solid lumps due to the characteristics peculiar to solid maleimides described above. Will end up.

Therefore, when dissolving the solid maleimides forming the agglomerates in acrylonitrile, when the solid maleimides are put into a maleimides dissolution tank (hereinafter simply referred to as a dissolution tank) from a storage container, the agglomerates become solids in the dissolution tank. The problem is that the solid maleimide charging nozzle is clogged, making the dissolution operation impossible.

Further, since the heat of dissolution of solid maleimides in acrylonitrile is a large endotherm, it is necessary to heat the solution in the dissolution tank in order to dissolve it.

However, since the injection of maleimides into the dissolution tank cannot be well controlled due to the formation of lumps, the liquid temperature in the dissolution tank fluctuates greatly up and down due to the insufficient injection speed of the maleimides into the dissolution tank. It was

When a large amount of maleimide crystals precipitate again from the acrylo solution of maleimides due to such a large fluctuation of the internal temperature, or when a large amount of maleimide masses enter the dissolution tank at one time. The amount of heat given to the solution by heating becomes less than the amount of heat necessary for dissolving the maleimides, and the solid solid maleimides remain in the dissolution tank as they are.

In such a case, the stirring operation of the internal liquid, which is indispensable for the dissolution operation, becomes impossible, and not only the internal liquid cannot be dissolved, but in some cases the internal liquid cannot be stirred. In some cases, heating may occur, leading to a serious situation such as polymerization of the solution.

Further, such a dissolution operation is usually carried out at a high temperature close to the boiling point of acrylonitrile, but acrylonitrile is a highly flammable compound and it is often easy to produce an explosive gas by mixing acrylonitrile vapor and air. Are known.

However, as described above, as a container for storing the solid maleimides, a container, a drum, a paper bag,
Although plastic bags and the like are used, it is difficult to completely replace the air inside the container with an inert gas, and it is inevitable that solid maleimides will be introduced into the tank for dissolving acrylonitrile from such a container. It was unavoidable that air existing in the space between solids of maleimides was also entrained in the dissolution tank to form explosive gas of acrylonitrile.

Thus, the existing method for dissolving solid maleimides in acrylonitrile could not be said to be completely completed.

Thus, a method for producing an acrylonitrile solution of maleimides without such a problem has been strongly demanded industrially.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a method for safely and easily producing an acrylonitrile solution of maleimides even if solidified maleimides in a storage container are used.

[Means for Solving the Problems] The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, solid maleimides have a property that solid particles come into contact with each other during storage to form lumps. However, the speed of agglomeration is very slow, and therefore, by crushing the agglomerates of the solid maleimides, it can be easily handled in a normal flake powder, tablet or granule state for a short time. It was discovered that it was possible to complete the present invention.

Despite the fact that solid maleimides have the property of forming lumps very easily, the finding that they can be easily handled in the form of powder etc. by crushing is totally surprising and at the same time solid. It must be said that it is of great value in the handling of solid maleimides.

Further, the present inventor can easily replace the atmosphere of the maleimides crushed as described above with an inert gas atmosphere such as nitrogen gas, and when dissolving the maleimides in acrylonitrile, or after the dissolution. The present invention has been completed in consideration of the finding that the composition of the gas phase portion of a solution can be easily set outside the explosion range.

That is, the present invention is: 1. When producing an acrylonitrile solution of solid maleimides, pre-crushed maleimides are filled in a closed container, and then from the container in a state where a substantially inert atmosphere is maintained. A method for producing an acrylonitrile solution of maleimides, which comprises dissolving maleimides in acrylonitrile by continuously or intermittently charging them into a dissolution tank.

2. When producing an acrylonitrile solution of solid maleimides, the maleimides are crushed in a closed container, and then the maleimides are continuously or intermittently transferred from the container to the dissolution tank while maintaining a substantially inert atmosphere. A method for producing an acrylonitrile solution of maleimides, characterized in that the maleimide is dissolved in acrylonitrile.

Is provided.

Hereinafter, the present invention will be described in detail with reference to FIG. 1 showing an example of a facility for dissolving maleimides.

In the present invention, paper male bags, plastic bags, solid maleimides filled and stored in containers such as containers,
Before being put into the maleimide-dissolving tank 6, it is crushed in advance and then filled in the closed container 1 attached to the dissolving tank 6. Alternatively, after the crushing is performed in the closed container 1, the dissolution tank 6
Be thrown into. A conventionally known method can be adopted as a method for disintegrating the lumps of solid maleimides.

Solid maleimides from storage containers such as paper bags to closed containers 1
After being moved to, the air in the closed container 1 is replaced with an inert gas such as nitrogen, carbon dioxide gas or argon by using the nozzles 2 and 3 attached to the closed container 1.

After such an operation, the closed container 1 is continuously or intermittently
The solid maleimides crushed from are poured into the dissolution tank 6.

Thus, according to the method of the present invention, the solid maleimide agglomerates do not block the maleimide discharge port 5 and do not form an explosive mixed gas of acrylonitrile and air. It is possible to produce acrylonitrile solutions of the class.

The dissolution tank 6 used for dissolving the solid maleimides has a heating coil or an outer heating part 10 and a stirrer 11, and further has a solid maleimide injection nozzle 9 and a maleimide acrylonitrile solution discharge port 8. Things are commonly used.

As a closed container 1 attached to this, a solid maleimide injection port 4 is provided at the upper part of the closed container, and a solid maleimide extraction port 5 is provided at the lower part, and the air in the closed container is filled with an inert gas. Due to the necessity of substituting into the above, a nozzle having an inert gas inlet nozzle 2 and an inert gas outlet nozzle 3 is used.

Further, in order to facilitate the operation when replacing the air in the container with an inert gas, a structure such that the airtightness of the closed container is maintained is preferable, specifically, the input of solid maleimides, A shutoff valve is attached to each part of the discharge port and the inert gas nozzle.

Further, if necessary, a crushing device for lumps of solid maleimides may be attached to the solid maleimide charging port (not shown). When it is necessary to strictly control the feeding rate of the solid maleimides, a rotary valve may be attached to the solid maleimide discharge port of the closed container.

As the material of the closed container, any material may be used as long as it is not attacked by acrylonitrile vapor or maleimides, but aluminum, stainless steel, carbon steel or the like is preferably used.

At the time of dissolution, it is preferable to fill the heating tank with acrylonitrile which has been heated in advance, and to add solid maleimides into it, but it goes without saying that the present invention is not limited to this. Although the temperature at the time of dissolution varies depending on the concentration of the maleimide acrylonitrile solution, the internal temperature is usually set to 10 to 70 ° C.

The rate of introducing solid maleimides into acrylonitrile varies depending on the amount of heat applied to the solution by heating, but is usually in the range of 1 to 1000 kg per ton of acrylonitrile per minute.

The maleimides used in the method of the present invention may be any solid ones, and examples thereof include the following compounds.

N-methyl maleimide, N-ethyl maleimide, N-hexyl maleimide, N-octyl maleimide, N-dodecyl maleimide, N-benzyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, N-nitrophenyl maleimide, N-methoxyphenyl Maleimide, N-methylphenyl maleimide, N-carboxyphenyl maleimide, N-hydroxyphenyl maleimide, N-chlorophenyl maleimide, N-dimethylphenyl maleimide, N-dichlorophenyl maleimide, N
-Bromphenylmaleimide, N-dibromophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide.

Further, for the purpose of preventing and stabilizing the polymerization of the acrylonitrile solution of maleimides, a polymerization inhibitor is added to the acrylonitrile solution in an amount of 0.0001 to 1% by weight, preferably 0.001 to 0.5.
It is preferred to use amounts in the range of weight percent. Examples of the polymerization inhibitor include methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenylamines, methylene blue, tert-butylcatechol, tert-butylhydroquinone, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, salicylic acid. Copper, thiodipropionic acid esters, mercaptobenzimidazole,
Triphenyl phosphites, alkylphenols,
Alkyl bisphenols, 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2'-thiobis-
(4-methyl-6-t-butylphenol) and triethylene glycol-bis- [3- (3-t-butyl-
5-methyl-4-hydroxyphenol) propionate] and the like.

The present invention has been described above, but the advantages provided by the present invention are as follows.

(1) An acrylonitrile solution can be easily produced by using solid maleimides that are agglomerated during storage.

(2) Solid maleimides stored in any storage container can be used.

(3) The rate of charging the solid maleimides into the dissolution tank can be freely controlled, and the dissolution operation is extremely easy.

(4) Since the explosive mixed gas of acrylonitrile and air is not formed, the solution can be manufactured extremely safely.

(5) An acrylonitrile solution can be produced inexpensively with simple equipment.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a maleimide-dissolving facility used when carrying out the method for producing an acrylonitrile solution of maleimides of the present invention. 1 ... Airtight container, 2 ... Inert gas injection nozzle, 3 ...
Inert gas discharge nozzle, 4 ... Maleimide injection port, 5
...... Maleimide discharge port, 6 …… Maleimide dissolution tank,
7 ... Acrylonitrile charging line, 8 ... Maleimide acrylonitrile solution discharge port, 9 ... Maleimide charging port, 10 ... Heating outer part, 11 ... Stirrer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-53771 (JP, A) JP-A-1-250348 (JP, A) JP-A-1-250347 (JP, A) JP-A-1- 250346 (JP, A) JP-A 1-156958 (JP, A) JP-A-62-126167 (JP, A)

Claims (5)

[Claims] 1. When producing an acrylonitrile solution of solid maleimides, pre-crushed maleimides are filled in a closed container, and the maleimides are then removed from the container while maintaining a substantially inert atmosphere. A method for producing an acrylonitrile solution of maleimides, which comprises dissolving continuously or intermittently in a dissolving tank to acrylonitrile. 2. When producing an acrylonitrile solution of solid maleimides, the maleimides are crushed in a closed container, and then the maleimides are continuously transferred from the container to a dissolution tank while maintaining a substantially inert atmosphere. A method for producing an acrylonitrile solution of maleimides, characterized in that it is dissolved in acrylonitrile by intermittently or intermittently charging. 3. The closed container is an opper type container having an inert gas inlet / outlet nozzle, a maleimide input port and a discharge port.
Method described in section. 4. The maleimides are dissolved in acrylonitrile in the temperature range of 10 to 70 ° C.
The method according to item 2 or item 2. 5. The method according to claim 1 or 2, wherein the charging rate of maleimides to acrylonitrile is in the range of 1 to 1000 kg / min per ton of acrylonitrile.