JPH0791250B2 - Stabilization method of cationic vinyl monomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for stabilizing a cationic vinyl monomer. More specifically, the present invention relates to a stabilizing method for preventing deterioration of the cationic vinyl monomer during storage, transportation or production without impairing the polymerization reactivity of the cationic vinyl monomer and dramatically improving the stability.

(Prior Art) The cationic vinyl monomer represented by the general formula (1) is a fiber.
Applications such as fiber modifiers, water treatment agents, paper chemicals, pharmaceuticals and cosmetics
Is useful as a raw material monomer for cationic polymers
It is a thing. General formula (1)(However, R₁Is hydrogen or a methyl group, R₂, R₃Each independently charcoal
An alkyl group having 1 to 4 elementary atoms, X Is Cl^-Or 1 / 2S
O_Four ^2-, N = 1 to 4 are integers. ) Conventionally, N, N-dialkylaminoalkyl has been used for such applications.
(Meth) acrylate or its quaternary ammonium salt
It has been used a lot. The corresponding monomer has an ester group
Fatal because it is susceptible to hydrolysis in water because it has
It has drawbacks. In order to improve the drawbacks due to such hydrolysis,
Newly developed cationic vinyl monomer has general formula
The N, N-dialkylaminoalkyl (
T) acrylamide hydrochloride or sulfate. General formula
The cationic vinyl monomer represented by (1) is usually general
The unsaturated tertiary amine represented by the formula (2) is hydrochloric acid or sulfur.
It is produced by reacting an acid.

General formula (2) (In the formula, R ₁ , R ₂ , R ₃ and n are the same as in the general formula (1)) The unsaturated tertiary amine represented by the general formula (2) has excellent radical polymerizability, When the neutralized salt represented by the general formula (1) is changed to more unstable and easier to polymerize, in particular, an acid is reacted with a high-concentration aqueous solution of the unsaturated tertiary amine represented by the general formula (2) to produce an acid. When the cationic vinyl monomer represented by the formula (1) is produced, spontaneous polymerization is likely to occur during production, storage or transportation.

To prevent natural polymerization of the conventional cationic vinyl monomer represented by the general formula (1), a stabilizer such as hydroquinone, hydroquinone monomethyl ether, or t-butylcatechol is added in the same manner as other unsaturated monomers. Has been done. However, this kind of stabilizer does not always satisfy the storage stability even if added in a large amount to the cationic vinyl monomer represented by the general formula (1). Various stabilization methods have been proposed to solve such problems. For example, JP-A-50-151806 discloses a salt of N-nitrosophenylpyroxyamine,
No. -144519 discloses a method of adding an aromatic nitroso compound to an N, N-dialkylamino (meth) acrylate-based cationic vinyl monomer.

However, since these nitroso compounds have an extremely large inhibitory effect upon radical polymerization, they often impair the original polymerization reactivity of the monomer. On the other hand, in JP-A-54-46711, N, N-dialkylamino (meth) acrylate-based cationic monomers are added to oxalic acid, citric acid, malic acid,
A method of adding condensed phosphoric acid and salts thereof as a stabilizer has been proposed. Although such a compound is certainly effective, the N, N-dialkylaminoalkyl (meth) represented by the general formula (1) is more naturally polymerizable than the N, N-dialkylaminoalkyl (meth) acrylate-based cationic monomer. ) In fact, it is not always possible to obtain a sufficient stabilizing effect on acrylamide hydrochloride or sulfate.

From this point of view, as an intermediate method between the two, Japanese Patent Laid-Open No. 57-
The use of a chelating agent and a nitroso compound as a stabilizer in 109747 and the use of a chelating agent and a quinone compound as a stabilizer in JP-A-57-109749 are shown by the general formula (1). It has also been proposed for each cationic vinyl monomer. However, a nitroso or quinone compound used in combination with a chelating agent has a strong polymerization inhibiting effect, even if it is a small amount, and therefore it also impairs the original polymerizability of the monomer, so it cannot be said to be a drastic measure.

That is, the stability of the cationic vinyl monomer represented by the general formula (1) during storage and transportation or production is improved, and when the polymer is produced by radical polymerization of the monomer, adverse effects such as inhibition of polymerization are not exerted. The reality is that such a stabilization method has not been found.

(Means for Solving Problems) In view of such a current situation, the present inventors have improved the stability of the cationic vinyl monomer represented by the general formula (1) during storage, transportation or production, And, as a result of diligent study to find out a method that does not have an adverse effect such as polymerization inhibition when a polymer is produced by radically polymerizing the monomer, a polycarboxylic acid or a salt thereof is added to the monomer as a stabilizer. However, the spontaneous polymerization still occurs when the unsaturated tertiary amine represented by the general formula (2), which is a raw material of the cationic vinyl monomer represented by the general formula (1), is contained in the system. And the free acid (free acid of hydrochloric acid or sulfuric acid which is a raw material of the cationic vinyl monomer represented by the general formula (1)). Of.

That is, in the present invention, at least one selected from the group consisting of polycarboxylic acids and salts thereof as a stabilizer is added to the cationic vinyl monomer represented by the general formula (1) with respect to the cationic vinyl monomer. The method for stabilizing a cationic vinyl monomer is characterized in that the concentration of free amine in the cationic vinyl monomer is 0.3 wt.% Or less and the concentration of free acid in the cationic vinyl monomer is 1.0 wt.% Or less.

That is, the cause of the spontaneous polymerization of the cationic vinyl monomer represented by the general formula (1) is caused not only by a trace amount of metal (especially iron) contained in the system but also by a trace amount of free amine or free acid derived from the raw material. It is necessary to remove both causes at the same time, a trace amount of metal (particularly iron) is sealed with a polycarboxylic acid and a salt thereof as a chelating agent (stabilizer), and at the same time, a free amine in the monomer is sealed. Concentration 0.
It is necessary to reduce the concentration to 3 wt.% Or less and the free acid concentration to 1.0 wt.% Or less.

The polycarboxylic acid and / or the polycarboxylic acid and / or the poly (carboxylic acid) and / or the poly (carboxylic acid) and / or the poly (carboxylic acid) and / or the poly (carboxylic acid) and / or the poly (carboxylic acid) which are used for sealing a trace amount of metal (especially iron) in the system are preferably used only by reducing the free amine concentration to 0.3 wt. The object of the present invention is not achieved only by adding the salt of.

The cationic vinyl monomer represented by the general formula (1) used in the present invention is the N, N-dialkylaminoalkyl (meth) acrylamide hydrochloride or sulfate represented by the general formula (2). Examples of the monomer include N, N-dimethylaminoethylacrylamide, N, N-dimethylaminopropylacrylamide, N-methyl, N-ethylaminopropylacrylamide, N, N-dipropylaminopropylacrylamide, and other hydrochlorides or sulfates. Further, these meta forms are exemplified, but not limited thereto as long as they are represented by the general formula (1). Since the cationic vinyl monomer represented by the general formula (1) is a crystalline form itself and is very well soluble in water, the cationic vinyl monomer is usually produced in a high-concentration aqueous solution state.

Examples of the polycarboxylic acid used as a stabilizer in the present invention include, for example, citric acid, tartaric acid, oxycarboxylic acids such as malic acid, aminocarboxylic acids such as ethylenediaminetetraacetic acid and nitrilotriacetic acid, and so-called oxalic acid and the like. Examples include polycarboxylic acids. Furthermore, these alkali metal salts, ammonium salts and water-soluble amine salts can also be used as stabilizers. At least one selected from these groups is added as a stabilizer, and it is particularly preferable to add at least one or more kinds of oxalic acid and salts thereof.

The amount of these stabilizers added to the cationic vinyl monomer represented by the general formula (1) depends on the type of stabilizer, the concentration of free amine or free acid in the cationic vinyl monomer, and the concentration of metal in the system. (Although it depends on the iron concentration in particular, it is more than the concentration at which the metal in the system can be completely sealed, and adverse effects such as polymerization inhibition when the polymer is produced by radically polymerizing the cationic vinyl monomer. It is important to set the range so that it does not exceed. The addition range is 1 to 5000 ppm, preferably 50 to 2000 ppm, with respect to the cationic vinyl monomer represented by the general formula (1),
If it is less than 1 ppm, the stabilization effect is insufficient and 5000 pp
When it exceeds m, it is not preferable because it adversely affects the polymerization characteristics when polymerized and used.

In the present invention, if desired, other known stabilizers such as hydroquinone, hydroquinone monomethyl ether, and t-butyl catechol may be appropriately used in combination within the range not impairing the polymerizability of the cationic vinyl monomer.

On the other hand, the concentration of free amine or free acid in the cationic vinyl monomer represented by the general formula (1) also has a great influence on the stability of the cationic vinyl monomer.

As mentioned above, the addition of polycarboxylic acids and their salts is one factor of the natural polymerization, which can seal a trace amount of metal (especially iron) in the system, but it is another factor of the natural polymerization. The effect of free amine or free acid due to the raw materials in the cationic vinyl monomer represented by the general formula (1) cannot be eliminated.

In order to obtain a sufficient stabilizing effect of the cationic vinyl monomer represented by the general formula (1), not only polycarboxylic acid and salts thereof are added, but also the concentration of free amine in the cationic vinyl monomer is increased. It should be 0.3 wt.% Or less and the free acid concentration should be 1.0 wt.% Or less. More preferably, it is desirable that the free amine is not detected and the free acid concentration is 1.0 wt.% Or less. When the concentration of free amine or the concentration of free acid exceeds the above range, spontaneous polymerization tends to occur and the stabilizing effect is insufficient.

Next, as a method of adding the stabilizer, since the polycarboxylic acid and the salt thereof as the stabilizer have a main function of metal sealing, a cationic vinyl monomer represented by the general formula (1) is produced. Raw materials for processing, eg general formula (2)
It is preferable to add a predetermined amount of a part or the whole of the unsaturated tertiary amine phase shown in, or the hydrochloric acid or the sulfuric acid phase in advance to the cationic vinyl monomer after production. It is more effective than stabilizing the cationic vinyl monomer.

More preferably, generally, the hydrochloric acid or sulfuric acid phase contains a larger amount of metal, so it is desirable to add a part or all of a predetermined amount to the raw material phase in advance.

On the other hand, the method of adjusting the free amine concentration or the free acid concentration in the present invention is, for example, when the cationic vinyl monomer represented by the general formula (1) is produced in an aqueous solution state using raw materials that are usually used industrially or After that, the free amine concentration or the free acid concentration is determined by potentiometric titration, and if the free acid concentration is too high so as to fall within the above concentration range, it is released with the unsaturated tertiary amine represented by the general formula (2). If the amine concentration is too high, it can be adjusted with hydrochloric acid or sulfuric acid.

(Effects of the Invention) As described above, the present invention comprises adding a small amount of at least one selected from the group consisting of polycarboxylic acids and salts thereof to the cationic vinyl monomer represented by the general formula (1). In addition, by finely adjusting the free amine concentration or the free acid concentration in the cationic vinyl monomer, it has overcome the problems of the conventionally known stabilization method, has a stability effect during storage, and is excellent in use. It can be said that this is an excellent stabilization method that simultaneously has the excellent property of having excellent polymerization activity. Therefore, the monomer obtained according to the present invention is not only stable against deterioration during production to storage, but even when used for polymerization, it is extremely easy without abnormal polymerization by a conventionally known ordinary polymerization method. A high quality polymer having a high polymerization rate can be obtained.

(Examples) Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, parts and% are parts by weight and% by weight unless otherwise specified, and the method for testing the characteristics is as follows.

(1) Stability test method A sample (monomer aqueous solution) was filled in a brown glass pin so that the space volume was 20%, and the sample was left at 25 ° C under a tight stopper,
The presence or absence of polymer formation was examined over time. The production of the polymerization product was confirmed at the time when the sample exhibited the stringing phenomenon.

(2) Polymerization test A sample was added to a glass adiabatic polymerization apparatus equipped with a thermometer and a nitrogen gas injection tube stirrer, and after adjusting the pH to 3.0, the oxygen concentration in the system was adjusted to 0.5 ppm by nitrogen coupling. After that, 20 ppm of ammonium persulfate and 5 ppm of sodium bisulfite as a polymerization initiator were added and polymerized with respect to the monomer. The induction time until the initiation of the polymerization and the polymerization rate 2 hours after the initiation of the polymerization were checked by the iodometry method.

Examples 1 to 4 and Comparative Examples 1 and 2 1369 g of 35.8% sulfuric acid aqueous solution which is usually used industrially
Was placed in a four-necked 5 flask equipped with a stirrer, dropping funnel and thermometer, and then 1.025 g (N,
N-dimethylaminopropyl acrylamide sulfate (500 ppm equivalent) was added and uniformly dissolved. The liquid temperature was cooled to 10 ° C., and 1560 g of N, N-dimethylaminopropylacrylamide, which is usually used industrially, was added dropwise using a dropping funnel. At this time, the inside of the reactor was purged with nitrogen gas to carry out the reaction. During the dropwise addition of N, N-dimethylaminopropylacrylamide, the flask was cooled from the outside in order to remove the heat of neutralization and kept at 40 ° C or lower. After completion of the reaction, the reaction mixture was cooled to room temperature to obtain about 70 wt.% N, N-dimethylaminopropylacrylamide sulfate aqueous solution. When the free amine concentration of this product was determined by potentiometric titration, the free amine was 0.
It was 5%. This sample was used as Comparative Example 1, and as Comparative Example 2 and Examples 1 to 4, the N, N-dimethylaminopropylacrylamide sulfate aqueous solution was placed in a beaker and sulfuric acid was added later to perform various tests shown in Table 1. I got a sample. A stability test and a polymerization test were conducted on this product.

The test results are summarized in Table 1.

Examples 5-8 0.103 g of oxalic acid as a stabilizer (equivalent to 50 ppm with respect to N, N-dimethylaminopropylacrylamide sulfate),
Alternatively, similar to Examples 1 to 4 and Comparative Examples 1 and 2 except that 8.2 g (corresponding to 4000 ppm with respect to N, N-dimethylaminopropylacrylamide sulfate) of oxalic acid, citric acid or ethylenediaminetetraacetic acid-2 sodium salt is used. After producing an aqueous solution of N, N-dimethylaminopropyl acrylamide sulfate, the concentration of free amine or free acid in the aqueous solution was measured by potentiometry, and these concentrations were adjusted as shown in Table 1. A test sample was obtained. A stability test and a polymerization test were performed on these products.

The test results are summarized in Table 1.

Comparative Examples 3 to 6 For comparison, when no stabilizer was added, 1.025 g of oxalic acid and 0.205 g of 1,4-benzoquinone (quinone compound) (in N, N-dimethylaminopropyl acrylamide sulfate) were added. When used in combination with 100 ppm), cuperone (nitroso compound) 0.20 together with 1.025 g of oxalic acid
When used in combination with 5g, 16.4g of oxalic acid (8000ppm based on N, N-dimethylaminopropylacrylamide sulfate)
(Equivalent) When added, test samples were obtained in the same manner as in Examples 5 to 8, and safety tests and polymerization tests were performed on these samples.

The test results are summarized in Table 1.

As is clear from Table 1, the addition of polycarboxylic acids such as oxalic acid or their salts gives a free amine concentration of 0.3w.
When it exceeds t.% or when the free acid concentration exceeds 1.0 wt.%, it is insufficient to stabilize it at room temperature for 1 month or more, and at least one selected from the group consisting of polycarboxylic acids and salts thereof. With addition of free amine concentration 0.3w
It is necessary to keep t.% or less and free acid concentration 1.0 wt.% or less. The cause of the presence of the free amine or free acid in the cationic vinyl monomer represented by the general formula (1) is that the cationic vinyl monomer is generally industrially used because of the purity of the raw material and the measurement error of the raw material. This is because the aqueous solution is not manufactured in a completely neutralized form. It is also understood that if the concentration is adjusted without adding the stabilizer, the polymerization starts after only 2 days, and therefore the stabilizer must be used in combination.

Furthermore, it is clear that oxalic acid is particularly effective in the group consisting of polycarboxylic acids and their salts. or,
It is also clear that not only the effect of improving the stability but also the polymerization characteristics are not different as compared with the system without the stabilizer.
On the other hand, when oxalic acid is used in combination with 1,4-benzoquinone or cuperone, the stability is further improved, but the polymerization characteristics are markedly hindered. is there.

Claims (3)

[Claims] 1. A cationic vinyl represented by the general formula (1).
Monomers, polycarboxylic acids and stabilizers as stabilizers
At least one selected from the group consisting of
If you add 1-5000ppm to vinyl vinyl monomer
The concentration of free amine in the cationic vinyl monomer
Keep the free acid concentration below 0.3 wt.% And below 1.0 wt.%
A method for stabilizing a characteristic cationic vinyl monomer. General formula (1)(However, R₁Is hydrogen or a methyl group, R₂, R₃Each independently charcoal
An alkyl group having 1 to 4 elementary atoms, X Is Cl^-Or 1 / 2S
O_Four ^2-, N = 1 to 4 are integers. ) 2. The method for stabilizing a cationic vinyl monomer according to claim 1, wherein the polycarboxylic acid is oxalic acid. 3. The method for stabilizing a cationic vinyl monomer according to claim 1, wherein the salt of polycarboxylic acid is an alkali metal salt, ammonium salt or water-soluble amine salt of oxalic acid.