JPH10259169A - Method for stabilizing cationic monomer solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a cationic monomer solution with preventing an unexpected polymerization and without affecting bad influences to polymerization behaviors in a continuous polymerization process by adding dimethyoxybenzene as a polymerization inhibitor. SOLUTION: In polymerizing a cationic monomer expressed by formula I [R1 is methyl or H; R2 and R3 are each methyl, ethyl or propyl; R4 is methyl, ethyl, propyl or benzyl; A is an enzyme or NH; (n) is 1-3], e.g. N,N- dimethylaminoethyl (meth)acrylate methyl chloride quaternary salt, etc., to produce a cationic polymer expressed by formula II [(m) is a natural number), ten odd-several hundreds wt. ppm of dimethoxzybenzene (preferably a para derivative) based on the cationic monomer is added in a way, e.g. directly to a storage tank, the storage after dissolving in the cationic monomer, etc., to stabilize the cationic monomer during storage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for stably producing a cationic polymer which can be widely used as a polymer flocculant or paper chemical.

[0002]

2. Description of the Related Art In recent years, cationic polymers, which are widely used as polymer flocculants and paper chemicals, are produced by continuous polymerization for reasons of production efficiency and economical reasons, compact equipment, and high polymerization rate. The system is being adopted instead of the conventional batch system.

As a production method by continuous polymerization, a method using ultraviolet / visible light or radiation irradiation by a belt conveyor method can be cited, but a continuous polymerization method using ultraviolet / visible light is becoming widespread in terms of equipment and maintenance costs. In the case where the cationic monomer is continuously polymerized by ultraviolet / visible light, the cationic monomer and the photopolymerization initiator are generally preliminarily prepared in an adjustment tank. Further, a sensitizer, a diluting solvent, a chain transfer agent, a crosslinking inhibitor and the like are added and mixed. Next, the pH is adjusted, and after deoxygenation is further performed under nitrogen or reduced pressure, the mixture is continuously supplied to the polymerization step to be polymerized.

In order to stably maintain the quality of the cationic polymer obtained by continuous polymerization, process control such as illuminance on the polymerization surface, temperature, irradiation time, invasion of outside air, etc. in the polymerization step, and cationic monomer in the regulating tank are required. It becomes important to control the dissolved oxygen, pH, temperature, etc. of the body solution. However, when it is required to increase the molecular weight of the cationic polymer to several millions or more, as in the case of, for example, a polymer flocculant, generally, the dissolved oxygen of the cationic monomer solution in the adjustment tank is reduced by several tens. ~ Several hundred pp
In order to reduce to the order b, unexpected polymerization may occur in the regulating tank during continuous feeding.
Once the polymerization starts in the adjustment tank, the composition of the cationic monomer solution supplied to the continuous polymerization step changes over time, so the polymerization behavior in the continuous polymerization step changes, and stable quality cationic Can not be obtained.

In order to obtain a stable quality cationic polymer, a technique for preventing unexpected polymerization in a regulating tank for a certain period of time is required.

[0006]

To prevent unexpected polymerization of the cationic monomer solution in the regulating tank for a certain period of time, the addition of a polymerization inhibitor is considered to be effective. Strong polymerization inhibitors such as nitro, nitroquinone and benzoquinone are not preferred because they generally hinder the polymerization behavior in the continuous polymerization step and increase the risk of coloring the product. In general, phenol-based polymerization inhibitors are less colored and are less likely to inhibit the polymerization behavior in the continuous polymerization process.However, even if they are added in large amounts, they can prevent unexpected polymerization in the adjustment tank for a certain period of time. Sometimes you can't.

[0007]

SUMMARY OF THE INVENTION The present inventors have found that, for a period of time, unexpected polymerization of a conditioned cationic monomer solution in a conditioned tank is prevented and adversely affects the polymerization behavior in a continuous polymerization step. As a result of intensive studies on a polymerization inhibitor which does not affect the above, it was found that the problem could be solved by adding dimethoxybenzene, and the present invention was reached.

That is, the present invention is as follows. 1. Wherein R ₁ is a methyl group or a hydrogen atom, R ₂ and R ₃ are a methyl group, an ethyl group or a propyl group, R ₄ is a methyl group, an ethyl group, a propyl group or a benzyl group, A is an oxygen atom or NH, n polymerizes the cationic monomer represented by an integer of 1-3.) of 5 (wherein, R _1, R
₂ , R ₃ , R ₄ , A and n are the same as above. m indicates a natural number. In producing the cationic polymer represented by the formula (1), dimethoxybenzene is added to the cationic monomer solution represented by the formula (4) immediately before polymerization.
The storage stabilization method immediately before the polymerization of the cationic monomer solution represented by the formula:

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Embedded image 2. The cationic monomer represented by Chemical Formula 4 is represented by Chemical Formula 6 (wherein,
R ₁ represents a methyl group or a hydrogen atom, and n represents an integer of 1 to 3. 3. The method for stabilizing a cationic monomer solution according to the above 1, wherein the method is a cationic monomer represented by the following formula:

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The cationic monomers represented by Chemical Formula 4 include N, N-dimethylaminoethyl (meth) acrylate methyl chloride quaternary salt and N, N-diethylaminoethyl (meth) acrylate methyl chloride 4 Quaternary salt, N, N-dimethylaminopropyl (meth) acrylate methyl chloride quaternary salt, N, N-diethylaminopropyl (meth) acrylate methyl chloride quaternary salt, N, N-dimethylaminopropyl (meth) Acrylamide methyl chloride quaternary salt, N, N-
Diethylaminopropyl (meth) acrylamide methyl chloride quaternary salt, N, N-dimethylaminobutyl (meth) acrylamide methyl chloride quaternary salt, N, N-diethylaminobutyl (meth) acrylamide methyl chloride quaternary salt,
N, N-methylethylaminopropyl (meth) allylamidomethyl chloride quaternary salt, N, N-dimethylaminoethyl (meth) acrylamide methyl chloride quaternary salt and the like are exemplified.

There are ortho, meta and para isomers in dimethoxybenzene which is added as a polymerization inhibitor for the cationic monomer solution in the adjusting tank, but since the para-position is generally uncolored, Is more preferable. The addition amount of dimethoxybenzene is more than 10 ppm by weight based on the cationic monomer.
To several hundred ppm by weight. If the amount is less than 10 ppm by weight, the cationic monomer solution after the adjustment may be polymerized during storage. When the amount is more than several hundred ppm by weight, there is no influence on polymerization during storage or continuous polymerization, but it is economically unfavorable, but not limited thereto. Examples of the method of adding dimethoxybenzene include a method of directly adding the compound to a storage tank, a method of dissolving the same in a cationic monomer in advance, and then supplying the solution to the storage tank, but are not limited thereto.

[0011]

The present invention will be specifically described below with reference to examples. [Example 1] Storage stability test A thermometer, a nitrogen gas inlet pipe with a flow meter, an exhaust pipe, a stirrer,
N, N-dimethylaminoethyl acrylate containing 0.2 parts by weight of P-methoxyphenol as a polymerization inhibitor in a jacketed 3L glass container equipped with a bottomed valve.
2,000 parts by weight of an 80% by weight aqueous solution of methyl quaternary chloride, 667 parts by weight of pure water, 0.08 parts by weight of benzyldimethylketal as a photoinitiator, and 0.05 parts by weight of sodium diamine ethylenediaminetetraacetate as a sensitizer And 0.016 parts by weight of P-dimethoxybenzene, and the mixture was adjusted to pH with sulfuric acid.
The solution was adjusted to 3.5, and high-purity nitrogen gas was bubbled under light-shielded stirring to adjust the dissolved oxygen of the solution to 500 ppb. Thereafter, in order to prevent the invasion of air from the outside, the composition was aged for 48 hours at an internal temperature of 20 ° C. in a state where nitrogen was flown. No stringiness was observed even after 48 hours.

[Example 2] Storage stability test Preparation was carried out in the same manner as in Example 1 except that the amount of P-dimethoxybenzene was changed to 0.16 parts by weight. As a result, 4
After 8 hours, no stringiness was observed.

[Blank] Storage stability test Preparation was carried out in the same manner as in Example 1 except that P-dimethoxybenzene was not added. As a result, at 12 hours, stringiness was confirmed, and polymerization in the container was recognized.

Comparative Example 1 Storage stability test The same procedure as in Example 1 was carried out except that the amount of P-dimethoxybenzene was changed to 0.008 parts by weight. as a result,
Twenty hours later, stringiness was confirmed, and polymerization in the container was observed.

Comparative Example 2 Storage stability test Preparation was carried out in the same manner as in Example 1 except that 1.6 parts by weight of P-methoxyphenol was added instead of P-dimethoxybenzene. As a result, at 12 hours, stringiness was confirmed, and polymerization in the container was recognized.

Comparative Example 3 Storage stability test Phenothiazine was used instead of P-dimethoxybenzene.
Adjustment was carried out in the same manner as in Example 1 except that 008 parts by weight was added. As a result, no stringiness was observed even after 48 hours.

Example 3 Photopolymerization A temperature sensor was inserted, and a stainless steel tray having a depth of 1 cm, through which cooling water of 30 ° C. was passed, was set therein. The solution stored in Example 1 for 48 hours was used. Pour under a nitrogen atmosphere,
Irradiation was performed at ² W / m ^{2 with} a chemical lamp. When the temperature in the system reached the maximum temperature, cooling water was stopped, and irradiation was performed with a high-pressure mercury lamp at 50 W / m ² for 5 minutes. The intrinsic viscosity of the obtained polymer was measured in 1N NaCl using a Cannon-Fenske viscometer. The amount of residual monomer was measured by a high performance liquid chromatography method. Table 1 shows the results.

Example 4 Photopolymerization Polymerization was carried out in the same manner as in Example 3, except that the solution stored for 48 hours in Example 1 was replaced with the solution stored for 48 hours in Example 2. Table 1 shows the results.

[Blank] Photopolymerization A preparation solution containing only 0.2 parts by weight of P-methoxyphenol as a polymerization inhibitor was polymerized immediately after preparation in the same manner as in Example 3. Table 1 shows the results.

Comparative Example 4 Photopolymerization Phenothiazine was used instead of P-dimethoxybenzene.
A solution prepared in the same manner as in Example 1 except that 008 parts by weight was added was stored for 48 hours. Next, polymerization was carried out in the same manner as in Example 3 using the solution stored for 48 hours. Table 1 shows the results.

[0021]

[Table 1] Photopolymerization evaluation results

[0022]

By adding dimethoxybenzene to the cationic monomer solution, the storage stability immediately before the polymerization can be effectively improved without adversely affecting the polymerization step and the physical properties of the cationic polymer. Now you can.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 20/34 C08F 20/34

Claims (2)

[Claims] Wherein R ₁ is a methyl group or a hydrogen atom, R ₂ and R ₃ are a methyl group, an ethyl group or a propyl group, R ₄ is a methyl group, an ethyl group, a propyl group or a benzyl group; A represents an oxygen atom or NH, and n represents an integer of 1 to 3), and polymerizes a cationic monomer represented by Formula 2 (wherein R ₁ , R ₂ , R ₃ , R ₄ , A And n are the same as above.
m indicates a natural number. In producing the cationic polymer represented by the formula (1), dimethoxybenzene is added to the cationic monomer solution represented by the chemical formula (1) immediately before the polymerization, wherein the cationic monomer represented by the chemical formula (1) is added. Storage stabilization method immediately before polymerization of the monomer solution. Embedded image Embedded image 2. The cationic monomer represented by the chemical formula ₁ , wherein R ₁ is a methyl group or a hydrogen atom, and n is an integer of 1 to 3. The method for stabilizing a cationic monomer solution according to claim 1, wherein the solution is a monomer. Embedded image