JP2001139624A - Method for producing polyvinylimidazoline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily recovering highly purified polyvinylimidazoline from a polyvinylimidazoline-containing solution, particularly a method suitable for recovering polyvinylimidazoline having a high molecular weight. SOLUTION: A method for producing polyvinylimidazoline includes a process of adding the first solvent to a polyvinylimidazoline-containing solution to prepare a solution containing a fine crystal of the polyvinylimidazoline and a process of adding the solution containing the fine crystal of the polyvinylimidazoline to the second solvent to precipitate the polyvinylimidazoline.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing polyvinylimidazoline which is a compound useful as a polymer flocculant.

[0002]

2. Description of the Related Art Conventionally, as a method for producing polyvinylimidazoline, a polymer of acrylonitrile or methacrylonitrile is reacted with a polyamine, and polyvinylimidazoline or a salt thereof is lyophilized from the reaction solution.
A method of recovering by precipitation from a solution has been adopted. For example, Japanese Patent Publication No. 42-6271 describes a method of recovering from an aqueous solution containing polyvinyl imidazoline or a salt thereof by precipitation.

[0003] However, such a method of recovering a solidified polymer from an aqueous solution containing polyvinylimidazoline or a salt thereof requires not only a long time, but also requires pulverization in order to produce a product, and thus, it is industrially necessary. This has been a major issue as a simple manufacturing method.

Further, when producing polyvinyl imidazoline having a high molecular weight, there is a problem that the reaction solution becomes viscous and it becomes more difficult to recover and separate. In this case, the polyvinyl imidazoline collected and separated not only by the freeze-drying recovery method but also in all of the above-described methods forms a lump, and requires pulverization to produce a product. Further, there is also a problem that impurities are increased because unreacted substances are taken in when forming a lump.

[0005] In the conventional method for producing polyvinylimidazoline, not only the pulverization step is indispensable as described above, but also unreacted substances are easily taken in, so that it has not been industrially sufficiently satisfactory.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for easily recovering high-purity polyvinyl imidazoline from a solution containing polyvinyl imidazoline, and in particular, a method for recovering high-molecular-weight polyvinyl imidazoline. An object of the present invention is to provide a method suitable for recovering polyvinyl imidazoline.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for producing polyvinyl imidazoline in order to solve the above-mentioned problems. As a result, the solution containing polyvinyl imidazoline becomes a poor solvent for polyvinyl imidazoline. To produce a liquid containing microcrystals of polyvinylimidazoline, and then adding the liquid containing microcrystals of polyvinylimidazoline to a second solvent that is a poor solvent for polyvinylimidazoline to crystallize polyvinylimidazoline. By this, the fact that crystals do not solidify during crystallization, the obtained polyvinyl imidazoline does not color brown, and the fact that an odorless, granular or powdery solid can be obtained was found, and the present invention was completed. Reached.

That is, the present invention provides a method comprising adding a first solvent to a solution containing polyvinyl imidazoline to obtain a solution containing fine crystals of polyvinyl imidazoline, and then adding the solution containing fine crystals of polyvinyl imidazoline to the second solvent. A method for producing polyvinyl imidazoline, wherein polyvinyl imidazoline is precipitated by the method described above.

Hereinafter, the present invention will be described in more detail.

The solution containing polyvinylimidazoline used in the method of the present invention may be any solution containing polyvinylimidazoline as such or as a salt thereof. For example, polyvinylimidazoline may be prepared from a polymer containing a nitrile group and a polyamine. The reaction solution obtained at the time of the above is exemplified.

In the method of the present invention, a method for producing a solution containing polyvinyl imidazoline is not particularly limited. Therefore, a preferred embodiment of a reaction solution containing polyvinyl imidazoline will be described below.

When a reaction solution containing polyvinyl imidazoline is used, its production method may be any method as long as polyvinyl imidazoline is obtained by a known method.
Acrylonitrile polymer, methacrylonitrile polymer,
A copolymer of acrylonitrile and methacrylonitrile,
Examples thereof include those produced from a polymer containing a nitrile group and a polyamine. In this reaction, it can be produced using a conventionally known catalyst such as ammonium chloride, amine hydrochloride, sulfur and the like.

The polymer containing such a nitrile group may be a homopolymer or a copolymer of acrylonitrile and methacrylonitrile. Monomers that can be copolymerized with acrylonitrile and methacrylonitrile include vinyl chloride, vinyl bromide, vinyl halides such as vinyl fluoride, vinylidene halides such as vinylidene chloride, acrylic acid, methacrylic acid,
Unsaturated carboxylic acids such as itaconic acid and maleic anhydride and salts thereof, (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, methyl vinyl ketone, methyl isopropenyl ketone and the like Unsaturated ketones, vinyl esters such as vinyl acetate and vinyl benzoate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, (meth) acrylamide and its alkyl-substituted products, vinyl sulfonic acid, (meth) allyl sulfonic acid, p- Unsaturated sulfonic acids such as styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, (meth) acryloyloxyethylsulfonic acid and salts thereof, styrene, α-methylstyrene,
Basic vinyl compounds such as styrene such as chlorostyrene and its alkyl- or halogen-substituted products, allyl alcohol and its esters or ethers, vinylpyridine, vinylpyrimidine, vinylpyrrolidone, vinylimidazole, dimethylaminoethyl methacrylate and vinylbenzyldimethylamine And the like.

The polyamine to be reacted with the polymer containing a nitrile group includes 1,2 represented by the following formula (1).
-Diamines are preferably used.

H ₂ NCHR ¹ CHR ² NHR ³ (1) (wherein R ¹ , R ² and R ³ are each independently selected from the group consisting of hydrogen, aliphatic, araliphatic and aromatic groups) Examples of this polyamine include ethyleneamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine, diaminopropane, diaminobutane, and diamino. Pentane, diaminohexane,
Diaminoheptane, diaminooctane, diaminononane, diaminodecane, cyclohexylethylenediamine, benzylethylenediamine, phenylethylenediamine, methoxyphenylethylenediamine, dimethylphenylethylenediamine, tolylethylenediamine, N
-Cyclohexylethylenediamine, N-benzylethylenediamine, N-phenylethylenediamine, N-methoxyphenylethylenediamine, N-dimethylphenylethylenediamine, N-tolylethylenediamine, N
And diamines such as -methylethylenediamine, N-ethylethylenediamine, N-isobutylethylenediamine, N-phenylethylenediamine, and N- (2-aminoethyl) ethylenediamine.

In the reaction between the above-mentioned polymer containing a nitrile group and a polyamine, the reaction is usually carried out at a temperature in the range of 60 to 200 ° C, more preferably at 70 to 180 ° C. Although the reaction can be carried out even at a temperature higher than 200 ° C., a polymer of acrylonitrile or methacrylonitrile as a raw material or a copolymer thereof may be broken in a molecular chain, resulting in a low molecular weight. If the reaction temperature is lower than 60 ° C., the reaction rate becomes extremely slow, and the amount of the catalyst may need to be increased.

This reaction is usually carried out in a liquid phase, but the reaction may be carried out at normal pressure or under pressure, as long as the raw materials are kept in a liquid, solution or suspension state. Also, in this reaction, ammonia is generated during the reaction, so in the case of a pressurized reaction, the pressure increases, but this ammonia can be removed during the reaction, or it may be removed after the reaction is completed. Can also. When the reaction temperature exceeds the boiling point of the raw materials, a method of performing the reaction under pressure, providing a condenser, or supplying the raw materials little by little can be employed.

In the thus obtained reaction solution containing polyvinyl imidazone phosphorus, if the polymer containing a nitrile group is dispersed, the reaction can be carried out using an excess amount of polyamine without using a solvent during the reaction. Alternatively, a solvent may be used. When a solvent is used, it is not preferable to use a substance that decomposes imidazoline such as water, but any solvent can be used without particular limitation as long as it is inert to the reaction conditions.

In the above reaction, if the reaction is carried out with an excessive amount of polyamine, a large amount of polyamine remains in the reaction solution, and unreacted polyamine remains even in the reaction using a solvent. Therefore, after the reaction, the unreacted polyamine must be removed from the reaction solution. In particular, when producing polyvinyl imidazoline having a high molecular weight, it is necessary to increase the amount of polyamine at the time of the reaction, and it is very important to remove the polyamine when recovering polyvinyl imidazoline from the reaction solution. In such a case, according to the method of the present invention,
By precipitating polyvinyl imidazoline, polyamine can be efficiently removed.

Then, a first solvent is added to the above solution containing polyvinyl imidazoline, and then the obtained solution containing microcrystals of polyvinyl imidazoline is added to the second solvent to obtain a granular or powdery solution. Polyvinylimidazoline can be precipitated, and impurities such as polyamine can be removed.

Here, the first solvent used in the method of the present invention is not particularly limited as long as it can generate microcrystals of polyvinylimidazoline by being added to a solution containing polyvinylimidazoline. In general, a solvent that is a poor solvent for polyvinyl imidazoline is used. For example, tetrahydrofuran, acetone, ether, dioxane, acetonitrile can be used. When such a solvent is used and added to a reaction solution obtained by reacting a polymer containing a nitrile group with a polyamine, a solvent that reacts with the polyamine remaining in the reaction solution, for example, acetone More preferably, a non-reactive solvent such as tetrahydrofuran is used. This is because acetone and the polyamine remaining in the reaction solution react with each other to generate a Schiff base, which may be taken into the precipitated polyvinylimidazoline.

As the second solvent, a liquid containing microcrystals of polyvinylimidazoline obtained by adding the first solvent can be added to the second solvent to precipitate polyvinylimidazoline. There is no particular limitation so long as it is a poor solvent for polyvinyl imidazoline. For example, tetrahydrofuran, acetone, ether, dioxane, acetonitrile can be used.

Although the first solvent and the second solvent can be selected in any combination, it is preferable that both are carried out with the same solvent in terms of simplicity of operation. Also,
Of the above solvents, tetrahydrofuran is preferably used in view of reactivity with polyamine and workability.

The amount of the first solvent used in the method of the present invention depends on the amount of the polyamine present in the solution containing the polyvinyl imidazoline, and a solvent that dissolves the polyvinyl imidazoline was used. Sometimes, it depends on the amount of the solvent. That is, when a solution containing polyvinylimidazoline is obtained without using a solvent, the amount of the first solvent may be 0.3 to 7 mol, preferably 1 to 5 mol, per 1 mol of the coexisting polyamine. In addition, when a solvent that dissolves polyvinyl imidazoline is used, the solubility of polyvinyl imidazoline differs depending on the type of the solvent, and thus cannot be specified.However, the amount of the first solvent may be further increased according to the amount of the solvent used. . If the amount of the first solvent is too small, the polyvinyl imidazoline does not become microcrystals, or it re-dissolves even if the microcrystals precipitate, making it difficult to finally obtain a granular or powdery solid. Sometimes it becomes. On the other hand, if the amount of the first solvent is too large, solids may be formed while impurities such as polyamine are taken into the crystals of polyvinylimidazoline.

The amount of the second solvent used in the method of the present invention is preferably such that the larger the amount of the liquid containing microcrystals of polyvinylimidazoline obtained by adding the first solvent, the larger the amount of crystallization of polyvinylimidazoline. Becomes easier,
At least an amount equivalent to the volume of the first solvent used in the previous step is required.

The slurry solution of polyvinylimidazoline thus obtained is obtained by separating the solvent by a separation means such as filtration or centrifugal separation and drying to obtain a granular or powdery solid of polyvinylimidazoline as a product. Can be.

The polyvinylimidazoline obtained by the method of the present invention includes itself and a salt thereof. In the case of a polyvinyl imidazoline salt, it can be easily converted to a salt, for example, by contact with an acid. Specifically, by adding an equivalent amount of hydrogen chloride to polyvinylimidazoline, it can be converted to polyvinylimidazoline chloride. When a catalyst is used in the reaction for obtaining polyvinylimidazoline, if the catalyst is, for example, ammonium chloride (ammonium chloride), hydrochloride of polyvinylimidazoline can be produced by the generated hydrogen chloride.

[0028]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Polyacrylonitrile (weight average molecular weight 500000)
5 g and 40 g of 1-propanol were put in a flask, and the mixture was purged with nitrogen and stirred. Then, 30 g of ethylenediamine and 5 g of ammonium chloride were added to start heating. 9 at 95 ° C
After heating for an hour, it was cooled to give a viscous yellow solution. To this solution is added tetrahydrofuran 10
When 0 g was dropped, a viscous microcrystalline solution having a whitish color was obtained. Further, the microcrystal solution was taken out and dropped into 200 g of tetrahydrofuran to obtain a pale yellow granular solid. When this was dried, 11.5 g of polyvinylimidazoline granules were obtained. The content of ethylenediamine or ethenediamine hydrochloride remaining in the granules was 0.01% by weight or less and was odorless.

Comparative Example 1 A reaction was carried out in exactly the same manner as in Example 1, and 300 g of tetrahydrofuran was added dropwise to the resulting reaction solution, whereby a yellow solid was obtained. When this was dried, 12.7 g of massive polyvinyl imidazoline was obtained. Approximately 1.6% by weight of ethylenediamine or ethylenediamine hydrochloride remained in this solid, and an amine odor was emitted.

Comparative Example 2 A reaction was carried out in exactly the same manner as in Example 1, and the resulting reaction solution was taken out and dropped into 300 g of tetrahydrofuran.
A yellow lumpy solid resulted. 12.8 g when this is dried
Was obtained as a mass of polyvinyl imidazoline. Approximately 2.3% by weight of ethylenediamine or ethylenediamine hydrochloride remained in this solid, and an amine odor was emitted.

Example 2 A reaction was carried out in exactly the same manner as in Example 1, and 50 g of tetrahydrofuran was added dropwise to the resulting reaction solution, whereby a viscous microcrystalline solution having a white color was obtained. Further, the microcrystal solution was taken out and dropped into 250 g of tetrahydrofuran to obtain a pale yellow granular solid. When this was dried, 11.5 g of polyvinylimidazoline granules were obtained. The content of ethylenediamine or ethylenediamine hydrochloride remaining in the granules was 0.01% by weight or less and was odorless.

Comparative Example 3 A reaction was carried out in exactly the same manner as in Example 1, and 5 g of tetrahydrofuran was added dropwise to the resulting reaction solution. With continued stirring, fine crystals did not precipitate and remained a viscous solution. This solution was taken out and dropped into 295 g of tetrahydrofuran to form a yellow solid mass. When this was dried, 12.8 g of a massive polyvinyl imidazoline was obtained. Approximately 2.3% by weight of ethylenediamine or ethylenediamine hydrochloride remained in this solid, and an amine odor was emitted.

[0034]

According to the method of the present invention, the obtained polyvinylimidazoline does not need to be pulverized, such as granules or powder, and has high purity without coloring brown or giving off odor. Polyvinylimidazoline can be easily produced and is industrially useful.

Claims (7)

[Claims] (1) adding a first solvent to a solution containing polyvinylimidazoline to obtain a solution containing microcrystals of polyvinylimidazoline, and then adding a solution containing microcrystals of polyvinylimidazoline to a second solvent; A method for producing polyvinyl imidazoline, comprising depositing polyvinyl imidazoline. 2. The method for producing polyvinyl imidazoline according to claim 1, wherein the solution containing polyvinyl imidazoline is a solution obtained by reacting a polymer containing a nitrile group with a polyamine. 3. The method according to claim 1, wherein the first solvent is a poor solvent for polyvinyl imidazoline.
Or the method for producing polyvinyl imidazoline according to claim 2. 4. The method for producing polyvinyl imidazone according to claim 1, wherein the amount of the second solvent is equal to or more than the volume of the first solvent by volume. . 5. The amount of the first solvent is 0.1 to 1 mol of the polyamine present in the solution containing polyvinylimidazoline.
The method for producing polyvinyl imidazoline according to any one of claims 2 to 4, wherein the amount is 3 to 7 mol. 6. The method for producing polyvinyl imidazone according to claim 2, wherein the polymer containing a nitrile group is a homopolymer of acrylonitrile or methacrylonitrile. 7. The method for producing polyvinyl imidazone according to claim 2, wherein the polymer containing a nitrile group is a copolymer of acrylonitrile or methacrylonitrile.