JPH08198906A - Production of acrylamide-based polymer - Google Patents

Abstract

PURPOSE: To remarkably shorten the completion time of polymerization and obtain the subject polymer useful as a paper strengthening agent, etc., at a low cost by carrying out the polymerization in the presence of an ethylenediamine-based compound without deteriorating the solubility and molecular weight of the resultant polymer. CONSTITUTION: The polymerization of (B) an acrylamide-based monomer is carried out in the presence of (C) an ethylenediamine-based compound of the formula (R1 to R4 are each H or a 1-5C alkyl), preferably N,N,N',N'- tetramethylethylenediamine in polymerizing the monomer (B) using (A) a persulfate as an initiator to afford the objective polymer. Furthermore, the component (C) in a molar amount of >=3 times based on the component (A) is preferably added and, e.g. ammonium persulfate is preferably used. Water, etc., are preferably used as a polymerization solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high molecular weight polymer in a short time in the production of a high molecular weight acrylamide polymer mainly used as a paper strengthening agent and a flocculating agent. More specifically, in the production of a high-molecular-weight acrylamide polymer that initiates polymerization using persulfate, an ethylenediamine-based compound is added to accelerate the polymerization rate and a high-molecular weight polymer can be obtained without lowering the molecular weight. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art When an acrylamide polymer is used as an aggregating agent, the higher the molecular weight of the acrylamide polymer is, the better the aggregating effect is, and the smaller the amount can be used. The advantages of Further, in the field of paper strength agents, in recent years, high molecular weight ones have been required. Heretofore, as a method for producing a high-molecular-weight acrylamide polymer, a method has been generally performed in which the polymerization temperature and the concentration of the polymerization initiator are made as low as possible. However, as the molecular weight becomes higher, the polymerization liquid becomes a gel with the start of the polymerization, and the stirring becomes impossible immediately, and the temperature control becomes impossible. Therefore, in order to keep the polymerization temperature low, it is necessary to lower the polymerization initiation temperature and also lower the polymerization concentration in order to suppress the amount of heat generated by the polymerization. That is, in the production of a high-molecular-weight acrylamide polymer, the concentration of the polymerization initiator, the polymerization initiation temperature, and the polymerization concentration must all be lowered, the time until the completion of the polymerization becomes longer, and as a result, the productivity decreases. Will end up. If the concentration of the polymerization initiator is simply increased to increase the polymerization rate, the molecular weight will decrease. Thus, a method for producing a high-molecular-weight acrylamide polymer with high productivity without depending on the above correlation has not been found yet.

[0003]

The production of the high molecular weight acrylamide polymer has the above-mentioned production restrictions, and as a result, there are the following problems to be solved. That is, 1. It takes a lot of time to complete the polymerization, so not only is it restricted from the viewpoint of manufacturing facilities and equipment,
Lower productivity and higher manufacturing costs. 2. Since the concentration of the polymerization initiator is low, the reproducibility of the polymerization is low and the time until the completion of the polymerization is not constant. 3. Since the polymerization initiator concentration and the polymerization concentration are low, the polymerization is not completed and unreacted monomers remain.

[0004]

SUMMARY OF THE INVENTION In view of the above points, the present inventors have studied in detail the method for producing a high molecular weight acrylamide polymer, and as a result, produced an acrylamide polymer using persulfate as a polymerization initiator. In the method, by conducting the polymerization in the presence of an ethylenediamine-based compound, it is possible to produce a high-molecular-weight acrylamide polymer in a short time by accelerating the polymerization rate without lowering the molecular weight in an unpredictable manner. Invented.

That is, the present invention provides (1) in the polymerization of an acrylamide monomer using persulfate as an initiator,
A method for producing a high molecular weight acrylamide polymer, characterized in that the polymerization is carried out in the presence of an ethylenediamine compound represented by the following general formula (1) [Chemical Formula 2]:

[0006]

Embedded image (2) The method for producing a high molecular weight acrylamide polymer according to (1), wherein the general formula (1) is N, N, N ′, N′-tetramethylethylenediamine. 3) The method for producing an acrylamide-based polymer according to (2), characterized in that the molar ratio of the persulfate is 3 times or more.

According to the present invention, it is possible to reproducibly produce a high molecular weight acrylamide polymer, which has been difficult to produce by conventional methods.
In addition, it has become possible to do it quickly and efficiently, and it has become possible to reduce restrictions on manufacturing equipment. That is, as a method for producing a high molecular weight acrylamide polymer, it is effective to polymerize in a relatively low temperature range, and the polymerization is carried out by reducing the amount of the initiator to obtain a higher molecular weight. . The present invention is a method of producing a high-molecular-weight acrylamide polymer by polymerization using a persulfate as an initiator, by performing the polymerization in the presence of an ethylenediamine-based compound, hardly inducing a decrease in molecular weight, It is characterized in that the polymerization rate can be remarkably increased.

The present invention uses the ethylenediamine compound represented by the general formula (1) as a polymerization accelerator for accelerating such a polymerization rate. R ₁ , R ₂ and R in the general formula (1)
₃ , R ₄ are each independently H or a C _{1 to} C ₅ alkyl group, that is, methyl, ethyl, propyl, butyl,
Represents a pentyl group, in particular R is all methyl,
It is preferable to use N, N, N ', N'-tetramethylethylenediamine.

In order to allow the ethylenediamine-based compound to be present in the polymerization system during the polymerization, it suffices to add the compound to the polymerization system. However, there is no particular restriction on the timing of addition, and at least immediately before the polymerization. It is preferable to add an effective amount to the polymerization system. The compound may be added to the monomer in advance. In that case, 30 days or more,
For example, the effect of the present invention can be obtained without change even after 50 days.

The amount of the ethylenediamine-based compound used varies depending on the type of the ethylenediamine-based compound, the type of the monomer, other polymerization conditions, etc., but it is preferably about 3 to 30 times mol, and even more preferably the molar amount of the persulfate. 5-15
A double mole is added for use. If the amount added is too small, the effect of the present invention will not be obtained.

The acrylamide polymer (polyacrylamide) used in the present invention is a homopolymer of acrylamide (or methacrylamide) or one or more unsaturated monomers copolymerizable with acrylamide (or methacrylamide). And a copolymer with.

Examples of the copolymerizable monomer include a hydrophilic monomer, an ionic monomer, a lipophilic monomer and the like, and one or more kinds of these monomers can be applied. Specifically, as the hydrophilic monomer, for example, diacetone acrylamide,
N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N, N-diethylacrylamide, N-propylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N- Examples thereof include acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol (meth) acrylates, N-vinyl-2-pyrrolidone and the like.

Examples of the ionic monomer include acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, 2-
Acids such as acrylamido-2-methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N,
N-dimethylaminopropyl methacrylamide, N, N
Examples thereof include amines such as dimethylaminopropyl acrylamide and their tertiary or quaternary salts.
Dibasic acids such as maleic acid and fumaric acid may inhibit polymerization and are not preferred.

Examples of the lipophilic monomer include N, N-di-n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide and Nn-
Hexyl methacrylamide, Nn-octyl acrylamide, Nn-octyl methacrylamide, Nt-
N-alkyl (meth) acrylamide derivatives such as octyl acrylamide, N-dodecyl acrylamide, N-n-dodecyl methacrylamide, N, N-diglycidyl acrylamide, N, N-diglycidyl methacrylamide, N- (4-glycid N- (ω-glycid such as xybutyl) acrylamide, N- (4-glycidoxybutyl) methacrylamide, N- (5-glycidoxypentyl) acrylamide, N- (6-glycidoxyhexyl) acrylamide Xyalkyl) (meth) acrylamide derivative, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylate derivatives such as lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate and glycidyl (meth) acrylate, olefins such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene and butene. Examples thereof include styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like. The amount of the unsaturated monomer used for the copolymerization varies depending on the type of the unsaturated monomer and the combination thereof and cannot be said unconditionally, but in the case of the hydrophilic monomer, it is generally 0 to 75% by weight,
The range for ionic monomers is generally 0 to 85% by weight, and the range for lipophilic monomers is generally 0 to 50% by weight.

Next, the above-mentioned monomers are polymerized to produce a high molecular weight acrylamide polymer. The polymerization is carried out by radical polymerization, and persulfate is essential as a polymerization initiator. Examples of the inorganic oxidant persulfate include ammonium persulfate, potassium persulfate, sodium persulfate and the like.

In addition, in the polymerization of acrylamide monomers, the polymerization system gels, and as a result, it becomes difficult to remove the heat of polymerization. Therefore, it is usually left as it is after the initiation of polymerization. Therefore, the polymerization proceeds adiabatically, and the temperature of the polymerization system rises and rises from around 0 ° C to around 100 ° C. It is effective to use a new initiator in combination in order to promptly proceed the polymerization in such a wide temperature range. There are various types of such an initiator, and for example, an azo type initiator can be used. Among them, those effective in initiating polymerization in a temperature range higher than the medium temperature range are preferable. For example, azobis (2-amidinopropane) dihydrochloride, azobis (2-methylbutyronitrile), azobisisobutyronitrile,
Azobis (4-cyanovaleric acid), dimethyl azobisisobutyrate, azobis [2- (2-imidazolin-2-yl)
Propane] dihydrochloride, azobisisobutyramide, azobis [2- (hydroxymethyl) propionitrile] and the like can be mentioned.

Water is most preferred as the polymerization solvent used in the present invention. As water, industrial water can be used as it is, but ion-exchanged water, distilled water, and well water containing few impurities such as metal ions are preferable. Also, lower alcohols such as methanol and ethanol, acetone, tetrahydrofuran, dioxane, dimethylformamide,
A water-miscible polar solvent such as N-methylpyrrolidone can also be used in combination. These solvents are convenient because they can be used as the solvent when a poorly water soluble polymerization initiator is used. Polymerization is carried out using the above solvent, and the monomer concentration at that time is 2 to 70% by weight, preferably 5 to 50% by weight.
Is. Further, the addition amount of the polymerization initiator is 1 mol ppm to 5000 mol ppm, preferably 10 mol ppm to 500 mol ppm, relative to the monomer.

There is no particular restriction on the pH at the start of polymerization,
The pH is generally in the range of 3 to 13. The polymerization initiation temperature varies depending on the concentration of the polymerization initiation oxidant and the concentration of the monomer, but is generally -10
~ 40 ° C. After the initiation of polymerization, the temperature is raised by the heat of polymerization generated as the polymerization proceeds. When the polymerization concentration is low and stirring is possible, the temperature can be controlled and set to a desired temperature, but under normal conditions, the polymerization liquid often gels with the progress of polymerization. The temperature becomes uncontrollable and the temperature rises and is left as it is. The maximum temperature reached is almost uniquely determined by the polymerization initiation temperature and the concentration of polymerized monomers,
Usually, the polymerization conditions are set so as to be 50 to 110 ° C. The polymerization time varies depending on the kind of the monomer, but is generally 1 to
100 hours.

At the start of the polymerization, the atmosphere of the polymerization system may contain oxygen like air, but in order to carry out the polymerization rapidly and with good reproducibility, the oxygen is replaced with an inert gas such as nitrogen gas. It is preferable to keep. It is preferable to remove not only the gas in the polymerization container but also oxygen dissolved in the acrylamide monomer aqueous solution and the initiator aqueous solution.

More specifically, an acrylamide-based monomer aqueous solution from which dissolved oxygen has been removed is added to a previously deoxygenated polymerization vessel, the polymerization initiation temperature is set, and the previously deoxygenated polymerization initiator aqueous solution is stirred. A predetermined amount is added below to start the polymerization. During that time, in order to prevent air from being mixed, it is preferable to introduce an inert gas such as nitrogen gas into the polymerization container.

Although the temperature rises as the polymerization progresses, it is left to stand until the maximum temperature is reached. After reaching the maximum temperature, if necessary, the acrylamide polymer is obtained by leaving the temperature as it is or by subjecting it to heat treatment such as immersion in hot water.

When used in the form of an aqueous solution such as a paper strength agent, it can be used as it is or diluted with water to reduce the viscosity to give a product. On the other hand, in the case of a powdery product such as an aggregating agent, the polymerization conditions such as the polymerization concentration are set so that the polymerization liquid becomes a gel, and a polymer gel is obtained. The polymer gel thus obtained is chopped, dried and crushed to give a powder.

The acrylamide polymer produced by the above method has a molecular weight of about 2,000,000 to 20,000,000,
It is useful as a polymer flocculant and a papermaking agent (paper strength enhancer, drainage improver, retention improver, etc.).

[0024]

【Example】

[Example 1] 0.063 g of N, N, N ', N'-tetramethylethylenediamine (hereinafter referred to as TMED) as a polymerization accelerator
The temperature of 1480 g of a 20 Wt% aqueous solution of the added acrylamide monomer (about 5 times the mole of persulfate) was set to 15 ° C. After transferring this solution to a heat insulating container, the system was deoxidized by substitution with nitrogen at a flow rate of 2.1 l / min for 2 hours. A 0.075% aqueous solution of ammonium persulfate (hereinafter referred to as APS) as a polymerization initiator 20
g was added and the mixture was left to stir. The polymerization was completed when the temperature rise was stopped, and the polymerization was completed after standing for 1 hour. After the completion of the polymerization reaction, the polymer was taken out, cut into small pieces, finely divided using a meat grinder, and dried at 100 ° C. for 2 hours. Then, it was pulverized and pulverized into a sample for testing the physical properties of the polymer. Polymer properties were measured by adjusting a 5% aqueous solution of test sample,
It was filtered through a wire mesh of 0 mesh, and insoluble matter was measured from the residue on the mesh. Further, the relative viscosity of the filtrate was measured to measure the molecular weight of the polymer.

Example 2 TMED was used as a polymerization accelerator.
The temperature of 1480 g of a 20 Wt% aqueous solution of acrylamide monomer added with 0.063 g (about 10 times mol of persulfate) was set to 10 ° C. After transferring this solution to an insulated container, the flow rate is 2.1 l / min.
The system was replaced with oxygen for 2 hours for deoxidation. 20 g of a 0.065% aqueous solution of APS was added as a polymerization initiator and left to stir. Thereafter, a polymer was produced in the same manner as in Example 1, and the physical properties of the polymer were measured. The measurement results are shown in Table 1.

Example 3 TMED was added in advance as a polymerization accelerator to 200 ppm with respect to the acrylamide monomer. After 50 days, the monomer concentration is 20 Wt
% Aqueous solution (1480 g) was prepared. Thereafter, a polymer was produced in the same manner as in Example 1, and the physical properties of the polymer were measured. The measurement results are shown in Table 1.

[Comparative Example 1] Under the same conditions as in Example 1, TMED as a polymerization accelerator was not added, and the same operation was performed thereafter to measure the physical properties of the polymer. The measurement results are shown in Table 1.

[Comparative Example 2] TMED was not added as a polymerization accelerator under the same conditions as in Example 2 and the same operation was performed thereafter to measure the physical properties of the polymer. The measurement results are shown in Table 1.

Comparative Example 3 TMED as polymerization accelerator
Was added, and thereafter, a monomer solution was prepared in the same manner as in Example 1. As a polymerization initiator, the amount of A is twice that of Example 1.
20 g of a 0.15% aqueous solution of PS was added and left to stir. Thereafter, a test sample was prepared and polymer physical properties were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

[0030]

[Table 1]

As is clear from Table 1, Example 1 is different from Comparative Example 1 in the absence of the ethylenediamine compound.
When the amount is 5 times the molar amount, the polymerization time can be shortened from 200 minutes to 160 minutes without lowering the molecular weight. In the absence of the ethylenediamine compound as in Comparative Example 3,
When the polymerization was carried out for the same polymerization time as in Example 1, the molecular weight was reduced from 12 million to 7 million, whereas it can be seen that the present invention can produce the polymer in a short time without lowering the molecular weight. Further, when the molecular weight was further increased in the absence of the ethylenediamine-based compound as in Comparative Example 2, the polymerization time was 308 minutes, which was extremely long, whereas in Example 2 of the present invention, 192 An equivalent polymer can be produced in a short time of a minute. When the ethylenediamine-based compound of the present invention is added to the acrylamide-based monomer in advance as in Example 3, the effect of the present invention can be obtained even after 50 days. By the way, regarding the solubility (insoluble content), no significant difference was observed.

[0032]

INDUSTRIAL APPLICABILITY According to the present invention, by carrying out the polymerization in the presence of an ethylenediamine-based compound, the polymerization completion time can be significantly shortened (about 3/4) as compared with the case where the ethylenediamine-based compound is not added. Shortening), unlike the results estimated from the general theory, the polymerization can be carried out without lowering the solubility and molecular weight of the obtained polymer. Moreover, since the concentration of the polymerization initiator is not extremely low, the amount of unreacted monomer remaining is very small, the reproducibility of the polymerization is good, and the completion time of the polymerization is almost constant. As described above, the unreacted monomer remains very little and the polymerization can be performed with relatively high reproducibility, and the completion time of the polymerization can be shortened without deteriorating the performance of the high molecular weight acrylamide polymer. Furthermore, it can be added to the raw material monomer at any time and can be polymerized without changing other equipment or operations, which can reduce restrictions from the aspect of manufacturing facilities and equipment, and greatly improve productivity. The cost can be reduced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaneko Mitsui Toatsu Chemical Co., Ltd. 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa

Claims (3)

[Claims] 1. Polymerization of an acrylamide monomer using persulfate as an initiator, wherein the polymerization is carried out in the presence of an ethylenediamine compound represented by the following general formula (1) [Chemical formula 1]. And a method for producing a high molecular weight acrylamide polymer. Embedded image 2. The method for producing a high molecular weight acrylamide polymer according to claim 1, wherein the general formula (1) is N, N, N ′, N′-tetramethylethylenediamine. 3. The method for producing an acrylamide polymer according to claim 2, wherein the molar ratio of the persulfate is 3 times or more.