JP2716373B2 - Method for preventing cloudiness of acrylonitrile solution of maleimides - Google Patents

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 an acrylonitrile solution of maleimides, and more particularly to a method for safely and stably handling a maleimide as an acrylonitrile solution in the presence of a polymerization inhibitor.

In the present invention, the term "handle" refers to the transportation of maleimides in acrylonitrile solution by tank truck, storage in tanks, pipes,
This means transfer via a pipe including a valve, a nozzle, and the like (for example, a supply line from a storage tank of an acrylonitrile solution of a maleimide to a polymerization system).

[0003]

2. Description of the Related Art Maleimides represented by N-phenylmaleimide and the like include acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-acrylic rubber-styrene (AAS) resin, acrylonitrile-styrene (AS) resin, acrylonitrile-chlorinated resin. As a heat resistance improver such as polyethylene-styrene (ACS) resin,
It is widely used for copolymerization with monomers constituting these resins. In addition, it is a useful compound as a raw material for medicines, agricultural chemicals and the like.

[0004] Conventionally, maleimides which are solid at room temperature have generally been handled in the form of powder, flakes, tablets and the like. However, such solid maleimides become powdered during the transfer, generate a large amount of fine powder, and cause various problems such as deterioration of the working environment. In order to solve these problems, the present applicant has previously proposed a method for safely and stably handling maleimides in the form of an acrylonitrile solution in the presence of a polymerization inhibitor (Japanese Patent Publication No. Hei.
-12057). This method of handling maleimides in the form of an acrylonitrile solution is currently widely used industrially because it is excellent in solving the above problems.

[0005] In addition, as a method of treating maleimides as an acrylonitrile solution, the applicant of the present invention disclosed a method in which an acid content of the maleimides in the acrylonitrile solution was 0.3% by weight.
(JP-A-64-61456) and the acid content of maleimides in an acrylonitrile solution is adjusted to 0.1.
A method of adjusting the concentration to 3% by weight or less and coexisting with a polymerization inhibitor (JP-A-1-250348) has been proposed.
These methods relate to a method for safely and stably handling the acrylonitrile solution while preventing corrosion of the metal material by the acrylonitrile solution of maleimides.

Further, the present applicant has proposed a novel method for treating maleimides in a molten state (Japanese Patent Laid-Open No. 3-2).
09363, JP-A-4-26673). In this method, maleimides are prepared in the form of an acrylonitrile solution at a temperature not lower than its melting point, that is, in a molten state, and a molecular oxygen content in a gas phase of 0.1% by volume or more or 10% by volume or less. It is to be handled by.

However, when the maleimides are handled in the form of an acrylonitrile solution by the method described in Japanese Patent Publication No. 3-12057, particularly when the maleimides are industrially handled in large quantities, the acrylonitrile solution may become colored or cloudy. It has been found that stability may be impaired. For example, after washing, when the acrylonitrile solution of maleimides is stored in a storage tank that has been left for a long time in an air atmosphere, or when the acrylonitrile solution of maleimides is used as a storage tank for the acrylonitrile solution of maleimides by diverting an apparatus used for another purpose. The solution may become colored or cloudy. This phenomenon not only impairs the commercial value of the acrylonitrile solution of maleimides, but also lowers the polymerization conversion rate in the production of the target resin, lowers the physical properties of the resin such as heat resistance, and further reduces the polymerization system from the storage tank of the acrylonitrile solution. In this case, the supply line to the hopper is closed, and the production of the resin itself becomes difficult.

[0008] Thus, there has been a strong industrial demand for a method for solving such problems and safely and stably handling maleimides in the form of an acrylonitrile solution.

The present inventors have examined the causes of undesired phenomena such as coloring or white turbidity of a solution of maleimides in acrylonitrile. As a result, when a small amount of peroxide is mixed in the acrylonitrile solution, the peroxide is decomposed and polymerized. Was generated, and it was speculated that a cloudy substance would be generated in the acrylonitrile solution. Specifically, for example, when a storage tank that has been left for a long time in an air atmosphere after cleaning is used, or when an apparatus used for another purpose is diverted to a storage tank of an acrylonitrile solution of a maleimide, the cleaning is insufficient. The organic substances adhering or remaining due to the oxidation are oxidized by oxygen in the air to generate an organic peroxide, which generates a polymer.

[0010] Further, it is considered that this organic peroxide further promotes the formation of a polymer when a monomer other than the maleimide and acrylonitrile is mixed into the acrylonitrile solution of the maleimide. In particular, a solution of maleimides in acrylonitrile is, as described above, ABS ABS.
Since the acrylonitrile solution is used for the production of a resin, an AS resin, or the like, styrene may be mixed into the acrylonitrile solution, thereby further accelerating the production of the polymer and causing an unexpected situation in actual handling. Specifically, for example, in the case of producing a styrene resin,
Backflow of styrene from the styrene monomer supply line to the storage tank of the acrylonitrile solution of maleimides in the polymerization system, and styrene mixing into the storage tank from the inert gas seal line connected to the styrene tank, appearing, and the acrylonitrile solution of the maleimides Coloration or cloudiness, or polymer formation proceeds. Such a phenomenon is not limited to styrene, and the same applies to aromatic vinyl compounds such as α-methylstyrene, p-methoxystyrene, p-methylstyrene, o, m, p-chlorostyrene, and p-bromostyrene. Was confirmed.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a method for safely and stably handling a solution of maleimide in acrylonitrile.

Further, the present invention provides a method for safely and stably handling an acrylonitrile solution of a maleimide even if a small amount of an impurity such as a peroxide or an aromatic vinyl compound is mixed in the acrylonitrile solution. The purpose is to provide.

[0013]

The present inventors have conducted intensive studies on a method for safely and stably handling a solution of maleimides in acrylonitrile. As a result, the molecular oxygen in the gas phase of the acrylonitrile solution was found to be stable in the acrylonitrile solution. The acrylonitrile solution is stable when the oxygen content of the gas phase part is adjusted to a specific range, and even if impurities such as a small amount of peroxide and aromatic vinyl compound are mixed, the stability is stable. The inventors have found that they can be handled in a stable state without impairing the properties, and have completed the present invention based on this finding. This finding is based on the fact that acrylonitrile is generally stored in a nitrogen atmosphere as specified in its disaster management guidelines.
It was completely unexpected.

[0014] Namely, the present invention is in the form of acrylonitrile solutions in the presence of maleimides the polymerization inhibitor, moreover
Conditions where organic peroxides or aromatic vinyl compounds are mixed
Upon handled in maleimide as the polymerization inhibitor
0.0001 to 1% by weight of p-methoxyfe
With Nord, and acrylonitrile solution of maleimide, characterized in that 0.01 to 10 volume% by volume of the gas mixture excluding maleimide and acrylonitrile molecular oxygen content of the gas phase portion of the acrylonitrile solution Is a method for preventing cloudiness . Hereinafter, the present invention will be described in detail.

The maleimides that can be handled according to 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 can be mentioned. The maleimides can be dissolved in acrylonitrile by any method such as charging the maleimides into acrylonitrile. In addition, the dissolution of maleimides depends on the boiling point of acrylonitrile (78.5).
C) is preferably performed at a temperature of 30 to 70 ° C, since acrylonitrile has a high vapor pressure.

The concentration of the maleimides in the acrylonitrile solution is not particularly limited, and the handling temperature, the mode of handling (for example, transportation or storage), the type of the copolymer produced using the acrylonitrile solution,
It can be appropriately determined in consideration of the production method and production conditions. For example, when it is used for producing a copolymer having a high maleimide content, it may be preferable to use a high concentration.

In the present invention, usually, the concentration of the maleimide is set to 40 to 80% by weight, and the acrylonitrile solution of the maleimide having the concentration in this range is handled at a temperature in the range of 30 to 70 ° C. According to the present invention, the concentration is 60 to
An acrylonitrile solution of maleimides at a high concentration of 80% by weight can be handled safely and stably. Book
In the invention, p-methoxyphene is used as a polymerization inhibitor.
Use Knoll.

[0018]

The amount of p-methoxyphenol used is 0.0001 to 1.0% by weight, preferably 0.001 to 0.1% by weight, based on the maleimides.

According to the present invention, when handling an acrylonitrile solution of a maleimide, the oxygen content of the gas phase of the acrylonitrile solution is adjusted to 0.01 to 10% by volume based on the volume of the gas mixture excluding the maleimide and the acrylonitrile. Preferably 0.1 to 8% by volume, more preferably 1
To 7% by volume.

The gas mixture excluding the maleimides and acrylonitrile usually comprises molecular oxygen and an inert gas such as nitrogen, carbon dioxide, helium, argon and the like. Nitrogen is particularly preferably used as the inert gas. Thus, as a preferable example of the gas mixture excluding the maleimides and acrylonitrile, there can be mentioned a mixed gas composed of molecular oxygen and nitrogen.

That is, in a preferred embodiment of the present invention,
The gas phase portion of the acrylonitrile solution of maleimides is composed of a gas mixture consisting of maleimides, acrylonitrile, molecular oxygen and nitrogen gas, and the oxygen content in the mixed gas of molecular oxygen and nitrogen gas is 0.01 to 10%. % By volume, preferably 0.1 to 8% by volume, more preferably 1% by volume.
~ 7% by volume.

The molecular oxygen content of the gas phase (based on the volume of the gas mixture excluding maleimides and acrylonitrile,
Below) is less than 0.01% by volume, the mixture of monomers other than maleimides and acrylonitrile,
Alternatively, it is not possible to prevent cloudiness of an acrylonitrile solution of a maleimide caused by contamination of a container such as a storage tank, or generation of a polymer. On the other hand, when the molecular oxygen content in the gas phase exceeds 10% by volume, the acrylonitrile solution of maleimides is colored. For example, as shown in Comparative Example 3, Gardner No. Increases from 7 to 13, which is not preferable. The coloring of the acrylonitrile solution of maleimides causes the coloring of the resin produced using the acrylonitrile solution, causes a decrease in the physical properties of the resin, and has a large adverse effect on the product resin, and the industrial disadvantages caused by the coloring of the acrylonitrile solution are as follows. Some are remarkable. Thus, a method for safely and stably handling a solution of maleimides in acrylonitrile without causing coloration has been desired.

There is no particular limitation on the method for controlling the molecular oxygen content of the gaseous phase portion of the acrylonitrile solution of maleimides to the range specified in the present invention. The gas phase may be replaced by using the mixed gas having the content. It is preferable to introduce the mixed gas into an acrylonitrile solution of a maleimide by stirring or bubbling, since the effects of the present invention can be exhibited in a short time.

[0025]

The main effects of the present invention are as follows.

(1) An acrylonitrile solution of maleimides can be handled safely and stably.

(2) Conditions that generate an organic peroxide which is considered to be a cause of coloring or turbidity of the acrylonitrile solution of maleimides, or formation of a polymer, for example, a storage tank which is left for a long time in an air atmosphere after washing. When used, or when the device used for other purposes is diverted and used as a storage tank for an acrylonitrile solution of maleimides, under conditions where organic substances adhere or remain due to insufficient washing Also, it is possible to effectively prevent the acrylonitrile solution from being colored or turbid, or from forming a polymer.

(3) When an acrylonitrile solution of a maleimide is mixed with an aromatic vinyl compound such as styrene which is a monomer other than the maleimide and the acrylonitrile and significantly impairs the stability of the acrylonitrile solution, It is possible to effectively prevent coloring, clouding, or formation of a polymer.

(4) An acrylonitrile solution of maleimides can be stably handled at a concentration of 40 to 80% by weight and at a temperature of 30 to 70 ° C.

(5) Even if the acrylonitrile solution of maleimides is stored for a long period of time, there is no coloration or turbidity of the solution, and no polymer is produced, so that the commercial value is not impaired.

(6) Since the acrylonitrile solution of maleimides does not discolor or become turbid or generate polymers even after long-term storage, the use of the acrylonitrile solution produces a resin having excellent hue and physical properties. can do.

[0032]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The oxygen content of the gas phase in the following Examples, Comparative Examples and Tables is based on the volume of the mixed gas excluding maleimides and acrylonitrile.

Example 1 A 500 ml flask equipped with a stirrer and a condenser was charged with 90 g of acrylonitrile and 10 mg of p-methoxyphenol as a polymerization inhibitor. This flask was placed on a water bath, and the internal temperature (temperature of the acrylonitrile solution) was adjusted to 65 ° C. by adjusting the water bath temperature. Next, while stirring, crystals of N-phenylmaleimide having a purity of 99.5% were added to 210
When g was added, the N-phenylmaleimide crystals were rapidly dissolved, and a completely clear yellow solution was obtained. The color tone of this solution was measured using a colorimeter (Delta colorimeter, manufactured by Tokyo Koden Co., Ltd.).
Measured by Gardner No. It was 7.

In this solution, 20 mm × 40 mm × 2 mm
A test piece of stainless steel (SUS304) having a size of ????????? is supplied, and then a nitrogen gas containing 7% by volume of molecular oxygen is supplied into the solution to replace the air in the gas phase with the nitrogen gas containing molecular oxygen. Later, it was sealed. The molecular oxygen content of the gas phase was 7% by volume.

When the solution was kept at an internal temperature of 65 ° C. for 60 days, the clarity of the solution did not change even after 60 days, and the color tone was Gardner No. It was 8.

When acrylonitrile was evaporated from the solution, bright yellow crystals were obtained. N-
When the phenylmaleimide content was analyzed by high performance liquid chromatography, it was 99.5%, and no polymerization was observed.

From these results, it was found that N-
It turns out that the acrylonitrile solution of phenylmaleimide can be handled stably.

The handling conditions and results are summarized in Tables 1 and 2, respectively.

Example 2 The same flask as used in Example 1 was charged with 100 g of acrylonitrile, 3 g of styrene and 10 mg of p-methoxyphenol as a polymerization inhibitor. Place the flask on a water bath and adjust the water bath temperature to bring the internal temperature of the flask to 65.
° C. Next, 200 g of N-phenylmaleimide crystals having a purity of 99.5% were added with stirring, and the N-phenylmaleimide crystals were immediately dissolved to obtain a completely clear yellow solution. The color tone of this solution was measured in the same manner as in Example 1. It was 7.

The same stainless steel test piece as used in Example 1 was placed in this solution, and nitrogen gas containing 7% by volume of molecular oxygen was supplied to the gas phase to supply air in the gas phase with oxygen. After purging with the contained nitrogen gas, the flask was sealed. The molecular oxygen content of the gas phase was 7% by volume.

When the solution was kept at an internal temperature of 65 ° C. for 30 days, the clarity of the solution did not change even after 30 days and the color tone was Gardner No. It was 8.

When acrylonitrile was evaporated from this solution, bright yellow crystals were obtained. N of this crystal
When the phenylmaleimide content was analyzed in the same manner as in Example 1, the purity was 99.5%, and no polymerization was observed.

From these results, it can be seen that even when styrene is mixed, the acrylonitrile solution of N-phenylmaleimide can be stably handled in a stainless steel container.

The handling conditions and results are summarized in Tables 1 and 2, respectively.

Comparative Example 1 In Example 2, the gas phase was replaced by using nitrogen gas instead of nitrogen gas containing molecular oxygen. After the replacement, the gas composition of the gas phase was analyzed by gas chromatography. As a result, the oxygen content was 0.001% by volume and was substantially not contained.

Subsequently, when the internal temperature was maintained at 65 ° C., 3
On the day, the solution became cloudy and became a viscous solution. When this was dropped into a vigorously stirred 1 liter methanol solution, a white polymer was precipitated.

The polymer was filtered and dried, and the weight was measured. As a result, it was found that 3% by weight was formed based on the total amount of N-phenylmaleimide and acrylonitrile used at the beginning, and that the polymer was clearly polymerized. Was.

The handling conditions and results are summarized in Tables 3 and 4, respectively.

Examples 3 to 6 Example 2 was the same as Example 2 except that the conditions such as the type of maleimide, the type of polymerization inhibitor, and the molecular oxygen content of the gas phase were changed as shown in Table 1. In the same manner, the acrylonitrile solution of maleimide was handled. The handling conditions and results are summarized in Tables 1 and 2, respectively.

Comparative Examples 2 to 3 The same procedures as in Example 2 were carried out except that the conditions such as the type of maleimide, the type of polymerization inhibitor, and the molecular oxygen content in the gas phase were changed as shown in Table 3. In the same manner, the acrylonitrile solution of maleimide was handled.

The handling conditions and results are summarized in Tables 3 and 4, respectively.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

Example 7 A mixture of a maleic anhydride-styrene-methyl methacrylate system and a stirrer and a cooler was used.
Reaction vessel with jacket (200 liter capacity, SUS30
4) was washed with hot water and steam, then dried in a stream of air at 100 ° C., and then diverted to a storage container for an acrylonitrile solution of N-phenylmaleimide.

After completely replacing the container with nitrogen gas,
60 kg of acrylonitrile and 4.5 g of p-methoxyphenol were added, and the temperature was raised to 50 ° C. Next, when 90 kg of N-phenylmaleimide was added and dissolved, it was rapidly dissolved, and a completely clear yellow solution was obtained. Further, when the gas phase was replaced with nitrogen gas and the oxygen content in the outlet gas was analyzed, no oxygen was detected.

Next, when the acrylonitrile solution was kept at 50 ° C. in this nitrogen atmosphere, the acrylonitrile solution became cloudy after 5 hours.

On the other hand, when the same operation as above was performed except that the nitrogen gas was replaced with nitrogen gas containing 7% by volume of molecular oxygen in place of the nitrogen gas, the acrylonitrile solution remained clear after 30 days. And no cloudiness of the solution was observed.

From the above results, it can be seen that clouding of the acrylonitrile solution, which is considered to be caused by contamination of the container, can be completely prevented by setting the molecular oxygen content in the gas phase to 7% by volume.

[0061]

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-300162 (JP, A) JP-A-63-316767 (JP, A) JP-A-62-145062 (JP, A) JP-A-6-316 49024 (JP, A) JP-A-4-235961 (JP, A) JP-A-4-26673 (JP, A) JP-A-3-209363 (JP, A)

Claims (6)

(57) [Claims] In the form of claim 1 acrylonitrile in the presence of a maleimide of a polymerization inhibitor solution, moreover organic peroxide addition
Uses p-methoxyphenol as the polymerization inhibitor when handling in a state where an aromatic vinyl compound is mixed .
There, and in maleimides, which comprises 0.01 to 10 volume% by volume of the gas mixture excluding maleimide and acrylonitrile molecular oxygen content of the gas phase portion of the acrylonitrile solution of acrylonitrile solution
How to prevent cloudiness . 2. A gas mixture excluding maleimides and acrylonitrile comprising a molecular oxygen and nitrogen gas.
The method of claim 1. Wherein the concentration of maleimides in the acrylonitrile solution is 40 to 80 wt%, the acrylonitrile
Or heating and maintaining the solution at 30 to 70 ° C.
2. The method according to 2. 4. The method according to claim 1 , wherein the molecular oxygen content of the gas phase is 0.1-8.
The method according to any one of claims 1 to 3, which is% by volume. 5. The method according to claim 1, wherein the amount of p-methoxyphenol used is 0.0001 to 1% by weight based on the amount of the maleimide. 6. An acrylonitrile solution containing stainless steel.
The method according to any one of claims 1 to 5, which is handled in the presence.
Law.