JPH0764810B2 - Method for transporting or storing maleimides - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for handling maleimides. More specifically, the present invention relates to a handling method such as transporting or storing maleimides in a molten state in which coloring is prevented.

[Conventional technology]

Maleimides are compounds useful as raw materials for resins, pharmaceuticals, agricultural chemicals, and the like.

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. 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 be extremely careful to avoid contact with the skin as much as possible.

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

Further, in many cases, solid substances are transported by filling paper bags, drums, containers, etc. with solid substances, but in these cases, the contact between maleimides and the human body is inevitable, and the human body is prevented from transferring the maleimides. It is inevitable that fine powder adheres.

In addition, it is difficult to transport solid substances by piping in order to avoid contact with the human body, and the inside of the pipe is blocked during pipe transportation. 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, as a method of solving the above-mentioned problems, a method of handling a maleimides as a solution of acrylonitrile, styrene or (meth) acrylic acid ester when transporting or storing it is disclosed in JP-A-62-126167 and JP-A-62-143911.
Nos. 62-145062 and 63-316767. Since these methods do not generate fine powders of maleimides that adversely affect the human body, it can be said that these methods are superior to the methods of handling them in a solid state. However, it is necessary to raise the temperature when handling a solution in which maleimides are dissolved in a high concentration in the method, but since the solvent used is a compound which itself has a polymerizable property, the maleimides are used for a long time. The solution cannot be kept hot. That is, impurities such as a polymer of the solvent itself and a copolymer of a maleimide and a solvent are generated, which causes coloring of the solution. The concentration of the solution is adjusted as it is, and ABS resin, A
It is used as a heat resistance improver for AS resins, AS resins and ACS resins to copolymerize with the monomers that make up these resins. At this time, when the colored maleimide solution as described above is used, the final product is colored, so that the commercial value is significantly reduced.

That is, it is difficult to say that the conventional method of handling maleimides in a solid state or a solution is a perfect method.

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to provide a novel method for handling maleimides.

Another object of the present invention is to provide a safe and simple method for transporting or storing maleimides which does not cause generation of fine powder during transportation or storage.

Another object of the present invention is to provide a method for handling maleimides, which is capable of preventing coloring of maleimides and maintaining high quality for a long period of time.

[Means for Solving the Problems]

The present inventors have diligently studied thermal stability such as coloration prevention of maleimides when handling maleimides in a molten product obtained by heating maleimides to a melting point or higher, that is, a liquid product without dissolving maleimides in a solvent. As a result, it was found that the above object can be achieved by suppressing the molecular oxygen concentration in the gas phase to a specific concentration or less for the coloring of maleimides, and the present invention has been completed based on this finding.

That is, the present invention is a maleimide characterized in that the molecular oxygen content of the gas phase part is 10% by volume or less, in the presence of a stabilizer, maleimides are transported or stored at a temperature of the melting point or higher. Transport or storage method.

Hereinafter, the present invention will be described in detail.

Examples of maleimides that can be handled by transportation or storage by the method of the present invention include, for example, N-methylmaleimide, N-ethylmaleimide, N-hexylmaleimide,
N-octyl maleimide, N-dodecyl maleimide, N
-Benzylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-nitrophenylmaleimide, N-methoxyphenylmaleimide, N-methylphenylmaleimide, N-carboxyphenylmaleimide, N-hydroxyphenylmaleimide, N-chlorophenylmaleimide, N-dimethylphenylmaleimide,
Examples thereof include, but are not limited to, N-dichlorophenylmaleimide, N-bromophenylmaleimide, N-dibromophenylmaleimide, N-trichlorophenylmaleimide, and N-tribromophenylmaleimide.

Stabilizers used when handling maleimides at temperatures above the melting point include, for example, methoxybenzoquinone;
-Methoxyphenol; Phenothiazine; Hydroquinone; Diphenylamines; Methylene blue; Zinc dimethyldithiocarbamate; Dialkyldithiocarbamate salts such as copper dimethyldithiocarbamate and copper dibutyldithiocarbamate; Copper salicylates; Thiodipropionate esters; Mercaptobenzimidazole; Alkyl substitution Examples thereof include, but are not limited to, hydroxybenzenes, alkylbisphenols, hindered phenols, phosphoric acid esters, phosphorous acid esters, and other phosphorus compounds. Further, the stabilizer may be used alone or in combination of two or more kinds.

In particular, at least one stabilizer selected from alkyl-substituted hydroxybenzenes, thiodipropionates, hindered phenols, phosphates, phosphites and other phosphorus compounds is at least the melting point of maleimides. These stabilizers are preferably used in the present invention because they are very effective in preventing the coloration of maleimides at the temperature of.

Examples of alkyl-substituted hydroxybenzenes include 2,
4-dimethyl-6-tert-butylphenol, 4-tert
-Butylcatechol, 2,5-di-tert-butylhydroquinone, 2-tert-dibutylhydroquinone, 4,4'-
Examples thereof include thio-bis (6-tert-butyl-m-cresol), but are not limited thereto.

Examples of thiodipropionates include ditridecyl-3,3'-thiodipropionate and dilauryl-
3,3'-thiodipropionate, ditetradecyl-3,3 '
-Thiodipropionate, distearyl 3,3'-thiodipropionate, dioctyl-3,3'-thiodipropionate and the like, but are not limited thereto.

Examples of the hindered phenols include 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), triethylene glycol-bis- (3- (3-t
-Butyl-5-methyl-4-hydroxyphenyl) propionate), bentaerythrityl-tetrakis (3-
(3,5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate, 2,
2-thio-diethylene bis (3- (3,5-di-t-butyl-4-hydroxyphenyl) bropionate), 1,6-
Hexanediol-bis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), tris- (3,5-di-t-butyl-4-hydroxybenzyl)
-Isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)
Benzene, N, N'-hexamethylenebis (3,5-di-t-
Butyl-4-hydroxy-hydrocinnamamide), 3,5
Examples thereof include-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester.
Among them, 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), triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate) and the like, but are not limited thereto.

Examples of the phosphite ester include triphenylphosphite, tris (nonylphenyl) phosphite, triethylphosphite, tris (2-ethylhexyl) phosphite, tridecylphosphite, tris (tridecyl) phosphite, tristearylphosphite. , Diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl monotridecyl phosphite, dilauryl hydrogen phosphite, dilauryl hydrogen phosphite, diphenyl hydrogen phosphite, tetraphenyl dipropylene glycol diphosphite, Tetraphenyl tetra (tridecyl) pentaerythritol tetraphosphite, tetra (tridecyl) -4,4'-isopropylidenediphenylphosphite Trilauryl trithiophosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris (2,4-dita-salibutylphenyl) phosphite, Examples include water-soluble bisphenol A / pentaerythritol phosphite polymer and hydrogenated phosphenol A / phosphite polymer.
It is not limited to these.

As the phosphoric acid esters and other phosphorus compounds,
Hexamethylphosphoric triamide, ethyl diethylphosphonoacetate, ethyl acid phosphate, β-
Chloroethyl acid phosphate, butyl acid phosphate, butyl pyrophosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, di (2-ethylhexyl) phosphate,
Ethylene glycol acid phosphate, (2-hydroxyethyl) methacrylate acid phosphate,
Tris (2-chloroethyl) phosphate, tris (dichloropropyl) phosphate, octyldichloropropylphosphate, phenyldichloropropylphosphate, trimethylphosphate, triethylphosphate, tributylphosphate, trioctylphosphate, tricresylphosphate, triphenylphosphate and the like can be mentioned. However, it is not limited thereto.

The amount of the stabilizer used in the present invention is 0.0001 to 1.0% by weight, preferably 0.001 to 0.1% by weight, based on the maleimides.
Is. The type of stabilizer is selected in consideration of the type of polymer to be produced, the method of polymerization, the initiator used, and the like.

In the present invention, it is necessary to suppress the molecular oxygen concentration in the gas phase part to 10% by volume or less. According to the knowledge of the present inventors, there is a clear relationship between the coloration of maleimides and the concentration of gaseous molecular oxygen, and maleimides are colored at a remarkably fast rate under a normal air atmosphere, This coloring is promoted under the condition where the molecular oxygen concentration is high in the absence of a stabilizer. When the maleimides are treated at a temperature above the melting point, the molecular oxygen concentration in the gas phase of 10% by volume or less is effective for preventing coloration, but the lower the concentration, the better the result. Especially, the gas phase is nitrogen, carbon dioxide,
More preferably, it is replaced with an inert gas such as argon.

The temperature at which the maleimides are handled is equal to or higher than the melting point of the maleimides, but from the viewpoint of reducing coloring, the melting point of the maleimides is 1 to 50 ° C., preferably 5 ° C.
A high temperature range of ~ 20 ° C is adopted.

〔The invention's effect〕

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

Since maleimides, which have a strong stimulative effect on the human body, can now be handled in liquid form instead of powder form, handling of maleimides is safe and easy.

It has become possible to store maleimides in a liquid state and in high quality for a long period of time.

When a polymer is produced by using the maleimides held in the liquid state, almost no coloring of the product is observed and a high quality final product can be obtained.

As described above, according to the method of the present invention, it is possible to handle the maleimides in a liquid state safely and with high quality while storing, transferring and the like.

〔Example〕

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

Examples 1-35 and Comparative Examples 1-3 Different types of maleimides, types of polymerization inhibitors, addition amounts thereof and conditions such as molecular oxygen concentration in the gas phase part are used to prepare maleimides and polymerization inhibitors. It was put into a sealable stainless steel container, placed in an oil bath at a predetermined temperature and heated. At this time, the gas phase portion was replaced with nitrogen gas, and the molecular oxygen concentration in the gas phase portion was adjusted to a predetermined concentration. After 1 to 3 months, the container was taken out and the appearance of the solution was visually observed. Further, the maleimides after heating are subjected to solution polymerization with styrene, and the appearance of the produced polymer is visually inspected. Table 1 (using alkyl-substituted hydroxybenzenes as a stabilizer), Table 2 (thiodipropionate as a stabilizer) The results are shown in Table 3 (using hindered phenols as stabilizers) and Table 4 (comparative examples).

(Reference Example) Synthesis of polymer 44 g of methyl ethyl ketone was charged into a 14-necked flask equipped with a stirrer, a cooler, a nitrogen gas introducing tube and a dropping funnel, and the gas phase was sufficiently replaced with nitrogen and heated to 80 ° C. A separately prepared mixed solution of 96.55 g of N-phenylmaleimide, 58.07 g of styrene and 460 g of methyl ethyl ketone and 0.77 g of azoisobutyronitrile and 11 g of methyl ethyl ketone were added dropwise over 4 hours while maintaining the internal temperature at 80 ° C. Stirring was continued for time. The reaction was then cooled, transferred to 2 l of methanol, filtered and dried to give 147.8 g of polymer. This polymer was a white powder and had a molecular weight of 100,000 (according to GPC analysis). By the same method, the molar ratio of various maleimides to styrene was set to 1, and azoisobutyronitrile was set to 0.5% by weight of the monomer, and the corresponding polymer was synthesized to determine the appearance.

Claims (7)

[Claims] 1. A maleimide compound, characterized in that a maleimide compound is transported or stored at a temperature above its melting point in the presence of a stabilizer under the condition that the molecular oxygen content in the gas phase is 10% by volume or less. Transport or storage method. 2. The method according to claim 1, wherein the stabilizer is an alkyl-substituted hydroxybenzene. 3. The method according to claim 1, wherein the stabilizer is a thiodipropionic acid ester. 4. The method according to claim 1, wherein the stabilizer is a hindered phenol. 5. The method according to claim 1, wherein the stabilizer is at least one compound selected from phosphoric acid esters, phosphorous acid esters and other phosphorus compounds. 6. The amount of the stabilizer used relative to the maleimides,
The method according to claim 1, wherein the amount is 0.0001 to 1% by weight. 7. The method according to claim 1, wherein the transportation or storage temperature is in the temperature range of not less than the melting point of maleimides and not more than melting point + 50 ° C.