JPH0672134B2 - Method for transporting and storing acrylonitrile solution of maleimides - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for transporting or storing maleimides as a solution of acrylonitrile.

Maleimides are useful compounds as raw materials for resins, pharmaceuticals, agricultural chemicals and the like, and the present invention provides a method for transporting and storing maleimides which is easy to handle, safe and simple.

[Conventional technology]

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

Particularly, during the transfer 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 be extremely careful to avoid contact with the skin as much as possible.

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

In addition, in many cases, solid substances are transported by filling solid substances such as paper bags, drums, and containers, but in these cases, contact between maleimides and the human body is inevitable, and the human body is not affected. It is inevitable that fine powder adheres.

In addition, the transfer of solid substances by piping to avoid contact with the human body is basically difficult, and the inside of the pipe is blocked during pipe transfer. There are severe restrictions on size, specific gravity, etc.

Thus, it must be said that there are a number of difficult problems in the transportation or transportation method of maleimides that are solid at room temperature. The same applies to the storage method.

On the other hand, a method of transferring, transporting or storing a maleimide as a solution of acrylonitrile is disclosed in JP-A-62-126167.

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

Usually, an acrylonitrile solution of maleimides is transported using a tank truck, a bulk container, a tank wagon, or a tanker.

However, the transfer or transportation of maleimides in the form of such an acrylonitrile solution has poor transport efficiency of maleimides, in other words, it is not an economical method because the transportation cost per unit weight of maleimides is high. there were.

Therefore, in order to make the transportation cost as low as possible, it may be possible to transport it in the form of a high-concentration acrylonitrile solution, but by increasing the concentration of maleimides in the acrylonitrile solution, maleimides are easily precipitated from the acrylonitrile solution. It is pointed out that the whole solution becomes a slurry or solidification, which makes it difficult to handle in terms of transportation or storage.

Further, in order to prevent the precipitation of such maleimides, it is necessary to keep a tank or a transportation pipe for transportation or storage of an acrylonitrile solution, a valve, or the like at a high temperature, which is very complicated and expensive. It also causes a big economical problem of requiring heat insulation equipment.

Such problems are particularly serious and fatal for transportation by acrylonitrile solution in winter or cold regions. Not only that, the boiling point of acrylonitrile is 77.3 ° C.
Considering that it is as low as (760 mmHg) and that it is highly toxic and extremely flammable, it must be said that maintaining the acrylonitrile solution at a high temperature poses a safety problem.

[Problems to be solved by the invention]

Therefore, the object of the present invention is to prevent the deterioration of the acrylonitrile solution of maleimides and to prevent maleimides from precipitating out of acrylonitrile, so that a high-concentration solution of high-quality maleimides can be easily and safely transported at low temperature. Or to provide a method of storing.

[Means for solving problems]

In order to achieve such an object, as a result of intensive studies by the present inventors, the deterioration of maleimides in acrylonitrile can be effectively prevented in the coexistence of a polymerization inhibitor, and the acrylonitrile solution of maleimides can be effectively removed. Precipitation, the higher the purity of the maleimides, the more easily it will precipitate near the saturation solubility, whereas in the acrylonitrile solution of maleimides 100 or more, preferably 200 to 100,000 average molecular weight, and maleimide It is possible to prevent maleimides from precipitating from an acrylonitrile solution by coexisting a compound inert to acrylonitrile, especially a compound represented by the formula (1) and the formula (2) described later, and easy even at low temperature. It was discovered that a stable supersaturated solution that can be handled by It came to complete Ming.

By adding a polymerization inhibitor and a compound having a relatively large molecular weight to the acrylonitrile solution of high-concentration maleimides, it is possible to prevent alteration of the maleimides in the acrylonitrile solution and prevent crystallization of the maleimides. Stable and safe handling as a supersaturated solution is quite surprising, and it must be said that it is a great advance in handling with such a solution.

That is, according to the present invention, an acrylonitrile solution containing a maleimide is allowed to coexist in the solution with a polymerization inhibitor and a maleimide and at least one compound selected from compounds represented by the following formulas (1) and (2). A method for transporting and storing maleimides characterized by being handled.

Formula (1) Formula (2) (However, in the formula, R ₁ and R ₂ are hydrogen, an alkyl group having 1 to 20 carbon atoms, a phenyl group, a benzyl group, a cyclohexyl group, a pyridyl group, a quinolyl group and a halogen substitution for these groups,
It is selected from those having carboxy group substitution and nitro group substitution. ) Hereinafter, the present invention will be described in detail.

Examples of maleimides that can be transported and stored by the method of the present invention include N-methylmaleimide, N-ethylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-benzylmaleimide, N-cyclohexylmaleimide. , N-phenylmaleimide, N-nitrophenylmaleimide, N-methoxyphenylmaleimide, N-methylphenylmaleimide, N-carboxyphenylmaleimide, N-hydroxyphenylmaleimide, N-chlorophenylmaleimide, N-dimethylphenylmaleimide, N- Dichlorophenylmaleimide, N-bromophenylmaleimide, N
-Dibromophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide and the like, but not limited thereto.

Examples of the polymerization inhibitor that should coexist in the acrylonitrile solution include methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenylamines, methylene blue, tert-butylcatechol, tert-butylhydroquinone, zinc dimethyldithiocarbamate, dimethyldithiocarbamine. Acid copper, copper dibutyldithiocarbamate, copper salicylate, thiodipropionates, mercaptobenzimidazoles, triphenylphosphites, alkylphenols, alkylbisphenols, hindered phenols, etc., but are not limited to these. Not a thing. The amount used is 0.0001 to 1.0% by weight, preferably 0.001 to 0,0% by weight based on the acrylonitrile solution of maleimides.
5% by weight. The type of polymerization inhibitor is selected in consideration of the type of polymer to be produced, the method of polymerization, the initiator used, and the like. For example, in styrene resins such as ABS resin and AS resin, when a polymer having high whiteness is desired as a final product, hindered phenols are effective as a polymerization inhibitor.

Although the reason for this is not clear, it is considered that the compound has an action of effectively suppressing the generation of coloring impurities in the final product produced during storage or polymerization of the acrylonitrile solution of maleimides.

Further, the compound to be allowed to coexist in the acrylonitrile solution is the compound represented by the formula (1) and the formula (2), and these compounds can be used as a mixture.
These compounds can also be used in combination with other compounds known as stabilizers for maleimides.

The amount of the compound used is 0.01 to 20% by weight, preferably 0.1 to 10% by weight, based on the maleimides in the acrylonitrile solution.

Although the effect of the compound varies depending on the kind and the amount added, generally, the addition temperature of 1% by weight of the compound can lower the precipitation temperature of the maleimides from the acrylonitrile solution over about 5 to 40 ° C.

If the addition amount is less than 0.01% by weight, the effect is low. On the contrary, if the addition amount exceeds 20% by weight, the polymerization reaction does not proceed promptly during the polymerization, and further there is a problem that the physical properties of the final polymer are impaired.

It is needless to say that the type and amount of the compound are also selected in consideration of the type of the final polymer prepared by using the acrylonitrile solution, the polymerization method, the polymerization conditions and the like.

The temperature at which the maleimides are dissolved in acrylonitrile is preferably not higher than the boiling point of acrylonitrile, and is usually 40 to 40 because acrylonitrile has a high vapor pressure.
Dissolution is carried out at 60 ° C and then handled in the range of -10 to 50 ° C.

In addition, although any method can be basically adopted as a dissolution method, acrylonitrile may be added to the maleimide and the compound, or the compound and the maleimide may be dissolved in the acrylonitrile. The maleimides used at this time may be solid or liquid.

Furthermore, in a preferred embodiment, a method of dissolving maleimides in acrylonitrile containing an acrylonitrile oligomer and / or polymer is conceivable, but the method is not limited thereto.

The concentration of maleimides in the acrylonitrile solution is determined by the temperature at which the solution is handled, the amount of the compound added, etc., but usually the higher the concentration of maleimides in the acrylonitrile solution, the cheaper the transportation cost is, so the concentration of 40-90% by weight. Is preferred.

〔The invention's effect〕

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

(1) Maleimides can be easily handled as a liquid without directly contacting the human body, and are easy to transport and store and safe.

(2) High-concentration maleimides can be stably and safely handled at a low temperature without precipitating maleimides.

(3) Since transportation and storage of high-concentration maleimides can be easily performed, transportation and storage costs are low.

(4) Since a high concentration of maleimides can be handled stably and safely, a final polymer having a high maleimide content can be obtained using the solution.

〔Example〕

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

Example 1 In a 500 ml flask equipped with a stirrer and a cooling tube, 200 g of N-phenylmaleimide adjusted to the following composition, 100 g of acrylonitrile, and 10 mg of p-methoxyphenol were added.

When the temperature of the water bath was adjusted and the internal temperature was adjusted to 50 ° C, a clear and clear acrylonitrile solution was obtained immediately after dissolution.

Although the saturation dissolution temperature of this solution is 45 ° C,
No precipitation of N-phenylmaleimide crystals was observed even when cooled to 25 to 30 ° C, and it was stable even in this temperature range even when vigorously stirred.

Further, when the temperature of the water bath was adjusted and the internal temperature was kept at 50 ° C. for 30 days, the clarity of the solution after the holding did not change and no foreign matter was found in the solution.

Subsequently, when acrylonitrile was distilled off from this solution under reduced pressure, bright yellow crystals were obtained.

When the purity of this product was measured by liquid chromatography, it was 99.6% by weight, and no change was observed.

Example 2 The stabilizer used in Example 1 was 10 mg of p-methoxyphenol.
In addition, 0.5 g of triethylene glycol bis [3 (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] was added. When this solution was cooled, crystals of N-phenylmaleimide were precipitated only at 25 ° C.

The saturated dissolution temperature of this solution was 45 ° C. Furthermore, this solution is stable even at vigorous stirring at 30 ° C,
No crystals were seen.

Furthermore, when the temperature of the water bath was adjusted and kept at an internal temperature of 50 ° C. for 90 days, the clarity of the solution after retention was unchanged and no foreign matter was found in the solution.

Then, when acrylonitrile was distilled off from this solution under reduced pressure, bright yellow crystals were obtained.

When the purity of this product was measured by liquid chromatography, it was 99.9% by weight, and no alteration was observed.

(However, it was converted to the purity not including the stabilizer.) Examples 3 to 13 N-phenylmaleimide 200 g and acrylonitrile 1000 g having the same composition as used in Example 1 and N-types and amounts of the polymerization inhibitor were changed. A solution of phenylmaleimide in acrylonitrile was prepared and stored at 50 ° C. for 30 days, and the results shown in Table 1 were obtained.

Comparative Examples 2 to 4 The deposition temperature was measured using N-phenylmaleimide having the following composition. The results are shown in Table 2.

N-phenylmaleimide composition N-phenylmaleimide 99.9% by weight maleic anhydride 0.1 〃 (molecular weight 98) Further, when the solutions of Comparative Examples 2 to 4 were stored at 60 ° C. for 30 days, it was found that what was clear before storage became cloudy and the viscosity of the solutions increased, and the polymerization was obviously performed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kentaro Sakamoto Inventor Kentaro Sakamoto 1 992 Nishi-oki, Okihama, Aboshi-ku, Himeji-shi, Hyogo Pref. Shinji Matsuura (56) (JP, A) JP 62-234063 (JP, A)

Claims (1)

[Claims] 1. Handling an acrylonitrile solution containing a maleimide in the presence of at least one compound selected from the compounds represented by the following formulas (1) and (2) and a polymerization inhibitor. And a method for transporting and storing maleimides. Formula (1) Formula (2) (However, in the formula, R ₁ and R ₂ are hydrogen, an alkyl group having 1 to 20 carbon atoms, a phenyl group, a benzyl group, a cyclohexyl group, a pyridyl group, a quinolyl group and a halogen substitution for these groups,
It is selected from those having carboxy group substitution and nitro group substitution. )