JPH04235961A - Method for handling maleimides - Google Patents

Abstract

PURPOSE:To prevent coloring and polymerization disadvantageous to utilization of maleimides which are compounds useful as a raw material for resins, medicines, agricultural chemicals, etc., and obtain a safe and easy method for handling. CONSTITUTION:Solid maleimides filled in a hermetically sealed vessel having a heating part can be kept in an intact high quality in the coexistence of a stabilizer under conditions of >=0.1vol.% content of molecular oxygen in the vapor-phase part for a long period. A safe and easy method for handling is provided by producing effects on prevention of coloring and polymerization through heating above the melting point in use and simultaneously keeping the maleimides in a molten state. Thereby, the maleimides having irritancy to human bodies can safely and readily be handled and transported or stored for a long period without deteriorating the quality.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for handling maleimides. More specifically, the present invention relates to a method for safely and easily handling maleimides by preventing coloration and polymerization of maleimides.

0002

BACKGROUND OF THE INVENTION Maleimides are compounds useful as raw materials for resins, medicines, agricultural chemicals, and the like.

Conventionally, maleimides that are solid at room temperature are powders,
It is generally sold in the form of flakes or tablets. However, such a form of maleimide contains fine powder of maleimide. Particularly, during the transportation of such solid maleimides, the maleimides become powdered, and a large amount of fine powder of maleimides is generated.

[0004] Maleimides themselves are irritating to the human body, and in particular, when inhaled as a fine powder, they irritate the nasal passages and throat, causing coughing and sneezing, and when left in contact with the skin, they cause inflammation and other undesirable properties. have. Therefore, when handling maleimides containing such fine powder, strict care must be taken to avoid contact with the skin as much as possible.

[0005] Therefore, a great deal of effort is required to prevent the generation of fine powder as much as possible when transporting maleimides, and to remove fine powder from maleimides after transport.

[0006] Furthermore, the transport of solid substances is often
Solid substances are packed and transported in paper bags, drums, containers, etc., but in these cases it is unavoidable that maleimides come into contact with the human body, and it is inevitable that fine powder of maleimides will adhere to the human body.

In addition, in order to avoid contact with the human body, transporting solid substances through piping is basically difficult and the inside of the pipe may become clogged during piping transportation, so in order to transport these solid substances stably, it is difficult to transport solid substances through piping. , severe restrictions are imposed on the shape, size, specific gravity, etc. of solids.

[0008] As described above, it must be said that there are a number of difficult problems in the method of transporting or transporting maleimides which are solid at room temperature. The same thing can be said about the storage method.

On the other hand, as a method for solving the above problems,
When transporting or storing maleimides, a method for handling them as a solution of acrylonitrile, styrene or (meth)acrylic acid ester was disclosed in JP-A-62-1261.
No. 67, No. 62-143911, No. 62-14506
No. 2 and No. 63-316767. These methods can be said to be superior to methods in which maleimides are handled in solid form because they do not generate fine powders of maleimides that have an adverse effect on the human body. However, in this method, when handling a solution in which maleimide is dissolved at a high concentration, it is necessary to raise the temperature, but since the solvent used is a compound that itself has polymerizability, maleimide cannot be dissolved for a long period of time. Such solutions cannot be kept at high temperatures. That is, impurities such as a polymer of the solvent itself and a copolymer of maleimides and the solvent are generated, which causes the solution to be colored. 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, ACS resins, etc., and is copolymerized with monomers constituting these resins. At this time, when a colored maleimide solution as described above is used, the final product is colored, resulting in a significant reduction in commercial value.

[0010] That is, the conventional methods of handling maleimides in solid form or in solution cannot be said to be a perfect method.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a new method for handling maleimides.

Another object of the present invention is to provide a safe and easy method for transporting or storing maleimides without worrying about the fine powder of maleimides coming into contact with the human body during transport or storage.

Another object of the present invention is to provide a method for handling maleimides that can prevent coloring and polymerization of maleimides and maintain high quality for a long period of time.

[0014]

[Means for Solving the Problems] As a result of extensive research into a method for safely and easily handling maleimides without dissolving them in a solvent, the present inventors have determined that solid maleimides can be processed under specific conditions to a melting point. It was discovered that the above purpose can be achieved by heating the maleimide to a molten state, once cooling and solidifying it, transporting or storing it, and then melting the maleimide again under specific conditions before using the maleimide. Based on this knowledge, the present invention was completed.

[0015] According to the present invention, there is no need to heat and store maleimides that are solid at room temperature in a solution or molten state, so there is no fear of deterioration such as polymerization, and long-term storage is possible. This is a completely surprising advance in the handling of maleimides.

That is, the present invention provides the method of heating a solid maleimide to a temperature higher than the melting point of the maleimide in the coexistence of a stabilizer under conditions where the molecular oxygen content in the gas phase is 0.1% by volume or more. , is a method for handling maleimides characterized by liquefying maleimides and then solidifying them before handling. Furthermore, the present invention provides the maleimides obtained by solidifying the above so that the molecular oxygen content in the gas phase is 0.1% by volume.
This method of handling maleimides is characterized by remelting them under the above conditions and handling them in a liquid state.

[0017]

[Operation] The present invention will be explained in detail below.

Examples of maleimides that can be transported, stored, and handled by the method of the present invention include N-methylmaleimide, N-ethylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, and the like. Alkylmaleimide; N-benzylmaleimide; N-cycloalkylmaleimide such as N-cyclohexylmaleimide; N-phenylmaleimide; N-nitrophenylmaleimide, N-methoxyphenylmaleimide, N-methylphenylmaleimide, N-carboxyphenylmaleimide, N- -Hydroxyphenylmaleimide, N-chlorophenylmaleimide, N-dimethylphenylmaleimide, N-dichlorophenylmaleimide, N
- Nitro group, alkoxyl group, alkyl group, carboxyl group, hydroxyl group such as bromphenylmaleimide, N-dibromphenylmaleimide, N-trichlorophenylmaleimide, N-tribromphenylmaleimide,
Examples include, but are not limited to, N-substituted phenylmaleimide substituted with a halogen atom or the like.

The method of the present invention is usually carried out in a closed container. Such an airtight container may be of any form as long as it has a heating means, such as a fixed tank such as a tank with an internal heating coil or a tank with an outer heating shell, as well as a tank wagon, a tank truck, or a bulk container. A mobile tank such as a container can be used.

[0020] The maleimides are filled in the airtight container and adjusted so that the molecular oxygen content in the gas phase is 0.1% by volume or more, preferably 0.1% by volume or more and 10% by volume or less, and Maleimides are heated and melted in the presence of a stabilizer, which will be described later, to form a liquid. Next, the liquid maleimide filled in this closed container is solidified in the closed container by natural cooling by standing to cool or forced cooling by external cooling. After being solidified in this way, the maleimide transported or stored has a molecular oxygen content of 0.1 in the gas phase before use.
It is heated and melted under conditions of volume % or more, preferably 0.1 volume % or more and 10 volume % or less, and is returned to a liquid state and handled.

A particularly preferred embodiment of the invention includes:
After filling a mobile tank such as a tank truck or a bulk container with a molten maleimide and solidifying it, the solid maleimide is transported to the destination, where it is heated and melted using a heating device attached to the container to form a liquid. It is treated as a type of maleimide.

Examples of the alkyl-substituted hydroxybenzenes used as stabilizers in the present invention include 2
, 4-dimethyl-6-tert-butylphenol, 4
-tert-butylcatechol, 2,5-di-tert
-Butylhydroquinone, 2-tert-dibutylhydroquinone, 4,4'-thiobis(6-tert-butyl-m-cresol), 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), pentaerythrityl-tetrakis (3-(3,5
-di-t-butyl-4-hydroxyphenyl)propionate), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2
-thio-diethylenebis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), 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-di-t-butyl-4-
Hydroxy-benzylphosphonate-diethyl ester and the like can be mentioned. Among them, 2,4-dimethyl-6-tert-butylphenol, 4-tert
-butylcatechol, 2,5-di-tert-butylhydroquinone, 2-tert-dibutylhydroquinone, 4,4'-thio-bis(6-tert-butyl-m-
cresol), 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-
It is preferable to use methyl-4-hydroxyphenyl)propionate since it is excellent in preventing coloration and polymerization of maleimides.

Examples of phosphites include triphenyl phosphite, tris(nonylphenyl) phosphite, triethyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, tris(tridecyl) phosphite, and tris(tridecyl) phosphite. stearyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl monotridecyl phosphite, dilauryl hydrogen phosphite, dilauryl hydrogen phosphite,
Diphenylhydrogen phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra(tridecyl)pentaerythritol tetraphosphite, tetra(tridecyl)-4,4'-isopropylidene diphenylphosphite, trilauryltrithiophosphite, bis( tridecyl) pentaerythritol diphosphite, bis(nonylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris(2,4-ditertiarybutylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite Examples include, but are not limited to, polymers such as hydrogenated bisphenol A/phosphite polymers.

Examples of phosphoric acid esters and phosphoric acid amides include ethyl diethyl phosphonoacetate, 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, octyldichloropropyl phosphate, phenyldichloropropyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tricresyl phosphate, triphenyl phosphate, hexamethyl phosphoric triamide, etc. However, it is not limited to these.

In the present invention, the amount of at least one phosphorus compound selected from alkyl-substituted hydroxybenzenes and/or at least one phosphorus compound selected from phosphorous esters, phosphoric esters and phosphoric acid amides is as follows: 0.0001~ for each maleimide
1.0% by weight, preferably 0.0001-0.1% by weight. The type of stabilizer is selected in consideration of the type of polymer to be produced, the polymerization method, the initiator used, etc.

According to the findings of the present inventors, the coloring and polymerization of maleimides is improved when the above-mentioned alkyl-substituted hydroxybenzene stabilizer and the above-mentioned phosphorus stabilizer are used in combination. It was found that a positive effect appeared. The ratio is not particularly limited, but the polymerization ratio of alkyl-substituted hydroxybenzenes and phosphorus compounds is 1:0.1 to 1:1000, particularly 1:1 to 1:10.
0 is preferred.

Furthermore, there is a clear relationship between the coloration and polymerization of maleimides during heating and melting and the molecular oxygen content in the gas phase, and when the molecular oxygen content in the gas phase is 0.
If the amount is less than 1% by volume, maleimides will polymerize at a high rate. In particular, in the absence of a stabilizer, the molecular oxygen content is 0.
If the amount is less than 1% by volume, this polymerization will be accelerated. In addition, polymerization can be suppressed when the molecular oxygen content is high, but
It was found that the coloration tends to progress.

In the present invention, the molecular oxygen content in the gas phase is 0.1% by volume or more, preferably 0.1% by volume or more and 1% by volume.
Good results can be obtained by keeping the content to 0% by volume or less, more preferably 1% by volume or more and 8% by volume or less. In particular, it is more preferable that the gas phase is replaced with an inert gas such as nitrogen, carbon dioxide, or argon.

The temperature at which the molten maleimide is handled is higher than the melting point of the maleimide, but from the viewpoint of reducing coloring, the temperature is 1 to 50° lower than the melting point of the maleimide.
A high temperature range of 5°C to 20°C is employed.

[0030]

[Examples] The present invention will be explained in more detail with reference to Examples below.

Example 1 A sealable cylindrical tank (length 5.6
18 tons of N-phenylmaleimide was filled into the tank (2.2 m in inner diameter, 20 m3 in internal capacity). The purity of this thing is 9
9.6% by weight, and triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4
-hydroxyphenyl)propionate] and 0.05% by weight of tristearylphosphite. After filling, the gas phase is filled with 5% by volume of molecular oxygen.
After purging with nitrogen gas so that the content was contained, steam at 110° C. was passed through the heated part to melt the contents, and then solidify by natural cooling.

After holding for one month, steam at 110°C was passed through the heated part to re-melt the contents, and the contents were collected.
This liquid was a clear yellow liquid with no generation of polymers. Further, when the purity was measured by liquid chromatography, it was 99.6%, and no change was observed. Furthermore, when this N-phenylmaleimide and styrene were solution-polymerized by the method shown in Reference Example, a white polymer without coloring was obtained.

Example 2 In Example 1, 0.005% by weight of 4-tert-butylcatechol and 0.05% by weight of distearylpentaerythritol diphosphite were added as stabilizers, and after filling, the gas phase was converted into a molecular state. Exactly the same operation was carried out except that the atmosphere was replaced with nitrogen gas so that the oxygen content was 10% by volume. After remelting, the N-phenylmaleimide was a clear yellow liquid with no polymers. Exactly the same results were obtained.

Reference Example Polymer Synthesis 44 g of methyl ethyl ketone was charged into a 1 liter four-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet pipe and a dropping funnel, and the gas phase was sufficiently replaced with nitrogen. heated to ℃. N-phenylmaleimide prepared separately from this 96.55
g, styrene 58.07 g and methyl ethyl ketone 4
60g of mixed solution and 0.77g of azoisobutyronitrile
A solution of g and 11 g of methyl ethyl ketone was heated to an internal temperature of 80°C.
The mixture was added dropwise over a period of 4 hours while maintaining the temperature, and stirring was continued for an additional hour. The reaction mass was then cooled, transferred to 2 liters of methanol, filtered and dried to yield 147.8 g of polymer. This polymer was in the form of a white powder and had a molecular weight of 100,000 (according to GPC analysis).

[0035]

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

[0036] Since maleimides, which are highly irritating to the human body, can now be handled in liquid form rather than in powder form, handling of maleimides has become safer and easier.

(2) Maleimides can now be stored in solid form for a long period of time without quality deterioration.

(2) When a polymer is produced using the remelted maleimide, a high-quality final product can be obtained with almost no coloration of the product.

As described above, by using the method of the present invention, it is possible to store, transport, and handle maleimides safely and with high quality.

Claims (2)

[Claims] Claim 1: By heating a solid maleimide to a temperature higher than the melting point of the maleimide in the coexistence of a stabilizer under conditions where the molecular oxygen content in the gas phase is 0.1% by volume or more,
A method for handling maleimides, which comprises turning the maleimides into a liquid state and then solidifying them before handling them. 2. The method according to claim 1, wherein after solidifying the maleimides, the maleimides are further melted under conditions where the molecular oxygen content in the gas phase is 0.1% by volume or more and handled in a liquid state.