JPS5828866B2 - Stabilization method for cationic vinyl monomers - Google Patents

Description

Detailed Description of the Invention This invention is based on the general formula (wherein R1 represents -H or -CH3, R2 represents -H or -CH3, and X○ represents C1-1BrCH3SO4-
Or represents 1/2S04-1.

) This relates to a method for stabilizing the cationic vinyl monomer (I) shown in (I).

Homopolymers of the cationic vinyl monomer (I) and copolymers of this monomer with acrylamide, vinylpyridine salts, methyl acrylate, etc. are used in industrial wastewater, urban sewage,
As a clarifying agent for accumulated wastewater, etc., and as a dehydrating agent for various sludges,
It is also used as a filler retention improver and paper strength enhancer in the paper manufacturing industry, as well as as a plastics improver and coating improver, and has promise for a variety of other uses.

Therefore, a large amount of cationic vinyl monomer (I) is expected to be consumed as a raw material for producing various cationic polymers.

The cationic vinyl monomer (■) usually has the following general formula (I
It is produced by adding hydrochloric acid, sulfuric acid, etc. to neutralize the unsaturated tertiary amine (II) represented by I), or by adding a quaternizing agent to cause a quaternization reaction.

(In the formula, R1 represents a part or -CH3.

) When producing the cationic vinyl monomer (I) by the above method, water or a non-aqueous solvent is usually used as the reaction solvent.

When water is used as a solvent, after the reaction is completed, the target product (cationic vinyl monomer (I)) is usually dissolved in water at a low concentration, or a part of the target product is in the form of crystals. When the reaction is carried out in a highly concentrated slurry state that causes precipitation, on the other hand, when the reaction is carried out in a non-aqueous solvent, the desired product is obtained by separating the formed crystals from the reaction mixture after the reaction is completed.

Whichever method is used, the obtained cationic vinyl monomer (■) is the unsaturated tertiary amine (n) which is the raw material.
It is unstable and polymerizes easily compared to other materials, and spontaneous polymerization tends to occur during the reaction or storage, especially when reacting at high concentration in an aqueous solution.

Although the cationic vinyl monomer (I) obtained by reaction in a non-aqueous solvent is relatively stable, it is still susceptible to polymerization in the step of recovering the solvent and drying the monomer after the reaction.

When the cationic vinyl monomer (I) undergoes spontaneous polymerization in this way, insoluble polymers may be mixed into the monomer, and it may be difficult to dilute the monomer to an appropriate concentration or mix a polymerization initiator when polymerizing the monomer. Since it becomes impossible to carry out normal polymerization, the commercial value is almost lost.

In order to prevent such spontaneous polymerization, hydroquinone monomethyl ether, hydroquinone, phenothiazine, N-nitrone phenylhydroxylamine, etc. have conventionally been added to the cationic vinyl monomer (I) as a stabilizer.

(7) 5. Hydroquinone monomethyl ether is the most typical stabilizer, but even when used in an amount of 1000 ppm or more relative to the cationic vinyl monomer (■), it still completely prevents the spontaneous polymerization of the monomer. I can't.

On the other hand, adding a large amount of stabilizer to obtain a sufficient effect is not at all preferable as it inhibits the normal polymerization of the cationic vinyl monomer (I), and it is also not desirable to add more stabilizers than necessary. Cationic vinyl monomer (I)
It has been shown that the stability of

Hydroquinone and phenothiazine are more effective as stabilizers than hydroquinone monomethyl ether, but even so, sufficient effects cannot be obtained unless they are added in amounts of several hundred ppm or more to the cationic vinyl monomer (■). vinyl monomer (
The coloration of I) is significant, and when it is polymerized, the polymer is colored brown or blackish brown, significantly damaging its commercial value.

N-40 sophenylhydroxylamine is much more effective as a stabilizer than hydroquinone, etc., and is usually used in amounts of several ppm to cationic vinyl monomer (I).
Addition of several tens of ppm is sufficient.

However, this substance also has a tendency to color the cationic vinyl monomer (■) even when added in a very small amount, and furthermore, it can be used as a monomer obtained by neutralizing unsaturated tertiary amine (II) with sulfuric acid. Production of materials that are particularly prone to spontaneous polymerization,
When used during storage, the amount added is insufficient and a larger amount is required.

As a result, the polymerization of the cationic vinyl monomer (I) is significantly inhibited, and for example, when polymerizing it, the polymerization may stop midway and a polymer with a large amount of residual monomers may easily grow, or there may be problems during polymerization. This may require a long induction period and a long polymerization time.

From this fact, the cationic vinyl monomer (I)
Not only is it highly effective in preventing the spontaneous polymerization of
There has been a demand for a stabilizer which can be easily controlled when the monomer is polymerized and which does not cause coloring of the polymerized product.

The present inventors conducted intensive research to find a stabilizer for the cationic vinyl monomer (I) that met these demands, and found that oxalic acid, citric acid, malic acid, condensed phosphoric acid, and salts thereof were suitable for the purpose. We have discovered that it is an excellent stabilizer and have arrived at the present invention.

That is, the present invention is based on the general formula (wherein R1 represents -H or -CH3, R2 represents -H or -CH3, and xe represents Cl-1BrCH3SO,
Or represents 1/2S04-1.

), at least one stabilizer selected from the group consisting of oxalic acid, citric acid, malic acid, condensed phosphoric acid, and salts thereof.
The present invention relates to a method for stabilizing cationic vinyl monomers characterized by using seeds.

The condensed phosphoric acid used in the present invention is a compound represented by the general formula: Hn+2PnO3n+1 and (I-IPO3)n (where n is an integer of 2 or more),
Suitable examples thereof include l-lyphosphoric acid, pyrophosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, tripolyphosphoric acid, and hexametaphosphoric acid.

In addition, the salts of oxalic acid, citric acid, malic acid and condensed phosphoric acid used in the present invention are the alkali metal salts of the respective acids,
Ammonium salts and water-soluble amine salts, such as the respective sodium, potassium and ammonium salts of oxalic, citric and malic acids, dimethylaminoethanol oxalate, sodium tripolyphosphate and hexametaphosphate. Examples include soda.

The amount of these stabilizers added to the cationic vinyl monomer (I) varies depending on the type of stabilizer, but is usually 0.1 to 5000 ppm, preferably 0.
．． Add 5-2000 ppm.

The stabilizer used in the present invention is a cationic vinyl monomer (I
), it is effective just by adding a small amount to the monomer, so it hardly inhibits the polymerization behavior when polymerizing the monomer.
Furthermore, the stabilizer used in the present invention is generally produced in large quantities and can be obtained at low cost, so the cationic vinyl monomer (I
) can reduce the manufacturing cost, and the appearance and color tone of the monomer and its polymer are not impaired.

In addition, these stabilizers are combined with cationic vinyl monomer (I
), conventionally known stabilizers may be used in combination, and mutual effects are often observed when used in combination.

For example, by adding a small amount of oxalic acid to the cationic vinyl monomer (I) to which hydroquinone monomethyl ether has already been added, the storage stability of the monomer can be increased compared to the case where each monomer is added alone.

The cationic vinyl monomer (I) used in the present invention is a salt of dimethylaminoethyl (meth)acrylate and a quaternary amine salt represented by the general formula (TI) described above,
More specifically, examples include dimethylaminoethyl (meth)acrylate sulfate, hydrochloride, dimethyl sulfate quaternary salt, methyl chloride quaternary salt, methyl bromide quaternary salt, and the like.

Although most of these cationic vinyl monomers (I) are themselves in crystalline form, they are very soluble in water, generally 401'/lo at room temperature.

r Shows solubility higher than water.

Therefore, these monomers can be produced in the form of very highly concentrated aqueous solutions.

When these monomers are produced in an aqueous solution, they are relatively stable when the monomer concentration is low, but when the concentration is high, for example 50% by weight or more, stability is lost and spontaneous polymerization occurs. It becomes easier to do.

Therefore, the stabilizer used in the present invention is particularly suitable when the cationic vinyl monomer (■) is produced in an aqueous solution at a concentration of 50% by weight or more, and excellent effects can be obtained.

The cationic vinyl monomer (I) is poorly soluble in most organic solvents except lower alcohols.

Therefore, in order to obtain the monomer in crystal form, the usual method is to react an unsaturated tertiary amine with a quaternizing agent or the like in an organic solvent such as acetonitrile, and then perform p-perisolation of the resulting crystals. However, in this case, the cationic vinyl monomer (■) tends to polymerize not only during the reaction but also during the step of drying the crystals separated from the reaction mixture or the step of recovering the organic solvent from the tear fluid.

The stabilizer in the present invention exhibits excellent effects when applied to each step in such cases.

Note that the production reaction of the cationic vinyl monomer (I) in an aqueous solution and in a non-aqueous solvent is usually carried out at a temperature ranging from room temperature to 150°C, but if carried out at too high a temperature, raw materials may be lost. Generally, the temperature is about 80°C to prevent polymerization of saturated tertiary amine as much as possible.
It is preferable to carry out the reaction in the above manner.

As is clear from the above description, the method of the present invention is not only applicable to the storage of cationic vinyl monomer (I), but also can be used to produce the monomer more advantageously than before. Monomers can be produced.

Next, the present invention will be explained using Examples and Comparative Examples.

Examples 1-5 Dimethylaminoethyl methacrylate 6331 content 1
Then, add the stabilizer listed in Table 1, and add the sulfuric acid aqueous solution 36 with a concentration of 53.7% by weight while stirring.
7Z was added dropwise over 10 minutes.

During the dropping of the sulfuric acid aqueous solution, the beaker was cooled from the outside to remove the heat of neutralization.

During the dropwise addition, the reaction temperature never exceeded 60°C.

After the reaction is completed, the reaction mixture is cooled to room temperature, and the time until the reaction product (dimethylaminoethyl methacrylate sulfate) begins to polymerize starting from the end of dropping the sulfuric acid aqueous solution and the presence or absence of coloration of the reaction product are measured. did.

The polymerization initiation point of the reaction product was determined as the point at which a glass rod was immersed in the reaction mixture and exhibited a stringy phenomenon when pulled up.

The results obtained are shown in Table 1.

Comparative Examples 1 to 9 Dimethylaminoethyl methacrylate was neutralized with sulfuric acid using the same apparatus and method as used in Examples 1 to 3.

However, 500 ppm of each of the compounds listed in Table 2 was used as a stabilizer.

After the reaction, the obtained reaction products were subjected to the same tests as in Examples 1-3.

The results obtained are shown in Table 2.

As is clear from Table 2, conventionally known compounds (Comparative Examples 1 to 4) and organic acids similar to the organic acids used in the present invention (
When dimethylaminoethyl methacrylate was neutralized with sulfuric acid using Comparative Examples 5 to 9) as a stabilizer, the reaction product polymerized within a relatively short period of time.

Example 6 In a 1 ton reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a gas inlet tube, 605z of dimethylaminoethyl methacrylate, 201' of pure water, 0.05P of oxalic acid, and 1 of hydroquinone were added. Monomethyl ether was added, and methyl chloride gas was introduced from the gas introduction tube at a flow rate of about 0.517 minutes while stirring while maintaining the temperature inside the flask at 55 to 65°C.

The reaction mixture is vigorously stirred during the reaction to facilitate absorption of methyl chloride gas into the reaction mixture.

The reaction mixture became transparent after about 190 S' of methyl chloride gas was introduced, but the gas was continued to be introduced for an additional 20 minutes.

This reaction yielded about 1 ky of an 80% aqueous solution of methacryloyloxyethyltrimethylammonium chloride.

The aqueous solution was then allowed to stand at room temperature for 6 months, but no signs of spontaneous polymerization were observed.

After standing for 6 months, the monomer concentration was diluted to 30% with water and a known polymerization initiator was added to attempt aqueous solution polymerization, which showed exactly the same polymerization behavior as before standing.

Example 7 Approximately 1 kg of an 80% aqueous solution of methacryloyloxyethyltrimethylammonium chloride was obtained using the same equipment as in Example 6 and following the same method except that oxalic acid was not added.

Next, 0.02 P of sodium hexametaphosphate was added as a stabilizer to the aqueous solution, and the mixture was left to stand at room temperature for 6 months, but no signs of spontaneous polymerization were observed.

On the other hand, when the mixture was left without adding sodium hexametaphosphate, spontaneous polymerization was observed after one month.

Examples 8 to 11 and Comparative Example 10-12 1 t of dimethylaminoethyl acrylate) 595P
Then, add the stabilizer listed in Table 3, and while stirring, add a 50% by weight aqueous sulfuric acid solution 405?
was added dropwise over 15 minutes.

During the dropping of the sulfuric acid aqueous solution, the beaker was cooled from the outside to remove the heat of neutralization.

During the dropwise addition, the reaction temperature never exceeded 50°C.

After the reaction was completed, the reaction mixture was cooled to room temperature, and the time from when the aqueous sulfuric acid solution was added dropwise until the reaction product (dimethylaminoethyl acrylate sulfate) started to polymerize was measured.

Claims (1)

[Claims] 1. An aqueous solution of a cationic vinyl monomer represented by the following general formula (I) with a concentration of 50% by weight or more, containing oxalic acid, citric acid, malic acid, condensed phosphoric acid, and salts thereof as stabilizers. A method for stabilizing a cationic vinyl monomer, which comprises adding at least one member selected from the group consisting of: (In the formula, R1 represents -H or -CH3, R2 represents -H or -CH3, xe represents Cl-1BrCH3SO4-
Or represents 1/2SO4-1. )2 The stabilization method according to claim 1, wherein the salts of oxalic acid, citric acid, malic acid, and condensed phosphoric acid are alkali metal salts, ammonium salts, and water-soluble amine salts. 3. Claim 1, wherein the amount of stabilizer added to the cationic vinyl monomer is 0.1 to 5000 ppm.
Stabilization method described in section.