JP4495834B2 - Acrylamide polymer composition and method for producing the same - Google Patents

Description

【００５７】
【発明の効果】
以上の説明から明らかなように、アクリルアミド系重合体にマンガン塩類および亜硫酸塩を含有させることにより、残留するアクリルアミド単量体の含有量を低減し、アクリルアミド系重合体水溶液の経時による粘度低下を抑制することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an acrylamide polymer composition having a small amount of residual monomer and having little decrease in viscosity over time even in an aqueous solution, and a method for producing the same.
[0002]
[Prior art]
Acrylamide polymers are used in many fields such as polymer flocculants, papermaking agents, soil conditioners, oil recovery agents, drilling mud thickeners, polymer absorbers and the like. In particular, when used as a polymer flocculant, it is required to have a high molecular weight in order to exhibit a sufficient aggregating action and to have a small amount of water-insoluble matter when the polymer is dissolved in water.
[0003]
On the other hand, when these acrylamide polymers are produced by a method that is usually employed industrially, acrylamide monomers remain, which may be inconvenient in terms of environmental burden and handling properties. It is preferable to reduce body concentration. For example, in the case of a water-soluble acrylamide polymer used as a polymer flocculant, the level of residual acrylamide monomer concentration in the industry is 0.2% by mass or less for general wastewater treatment, and for sludge treatment in waterworks Although it is 0.05 mass% or less, it has been aimed at further reducing in recent years.
[0004]
[Problems to be solved by the invention]
As a method of reducing the residual monomer in the acrylamide polymer proposed conventionally, there is a reduction method in the polymerization process by increasing the amount of initiator such as redox initiator and azo initiator and extending the polymerization time. When this method is adopted, there are cases where problems such as a decrease in molecular weight of the acrylamide polymer, that is, a decrease in performance and a decrease in productivity occur.
[0005]
For this reason, after obtaining the polymer containing a residual monomer, the method of reducing a residual monomer by post-processing is used. As such a method, (1) a method of extracting a residual monomer using an extraction solvent such as methanol, (2) a method of adding an alkali such as sodium hydroxide to the water-containing polymer after the polymerization, (3) A method of adding a monomer and a compound that can easily be added to Michael, such as sodium sulfite (USP 2,960,486, USP 3,755,280, Japanese Patent Laid-Open No. 56-103207, Japanese Patent Publication No. 61-23926) has been proposed. However, in some cases, the following problems may occur.
[0006]
That is, the method (1) requires the use and recovery of a flammable solvent, and there are concerns about inconveniences from the viewpoint of safety and economy. In the method (2), since it takes a long time to modify acrylamide or the like by adding an alkali, the productivity may be insufficient. The method of (3), especially the method of adding sulfite, is a method with good handleability and productivity, and is a method with a high effect of reducing residual monomers, but the viscosity of the acrylamide polymer is reduced, Furthermore, the viscosity of the aqueous polymer solution prepared with tap water or industrial water may decrease over time.
[0007]
As a method for suppressing the decrease in the viscosity of the polymer due to the addition of sulfite, a method of adding an alkali agent together with sulfite (Japanese Patent Laid-Open No. 9-302022) has been proposed. Although the molecular weight decrease in the production process of the polymer is suppressed, there is a case where the effect of suppressing the viscosity decrease with time of the polymer aqueous solution in the usage scene is not recognized.
[0008]
As an acrylamide polymer composition in which deterioration of physical properties is suppressed even in the state of an aqueous solution, a polymer composition characterized by containing aminophenol together with sulfite (Japanese Patent Laid-Open No. 11-343379) has been reported. However, there is a demand for a method having a higher effect of suppressing the decrease in viscosity.
[0009]
In view of the circumstances as described above, the present invention provides an acrylamide polymer composition having a low content of residual acrylamide monomer and a small decrease in viscosity over time of an aqueous acrylamide polymer solution and a method for producing the same. The purpose.
[0010]
[Means for Solving the Problems]
According to the present invention for achieving the above object, at least one sulfite selected from the group consisting of acrylamide polymers, manganese salts, alkali metal sulfites, alkali metal sulfites, and alkali metal pyrosulfites. a acrylamide polymer composition containing the salt, acrylamide-based polymer obtained from a monomer mixture containing acrylamide units 30 mol% or more, Ri soluble der, the content of manganese salts, manganese content is not more than 15 mass ppm to 1000 ppm by weight of the acrylamide polymer, the content of sulfite, characterized in der Rukoto 0.1 wt% to 15 wt% of acrylamide polymer An acrylamide polymer composition is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described.
[0012]
The acrylamide polymer composition of the present invention contains manganese salts and sulfites. For this reason, the content of the remaining acrylamide monomer is reduced, and a decrease in viscosity with time of the aqueous acrylamide polymer solution is suppressed.
[0013]
In the conventional technique using sulfite for reducing the residual monomer, when a large amount of sulfite is contained, the physical properties are lowered, for example, the viscosity of the acrylamide polymer is lowered, and the viscosity of the aqueous polymer solution is lowered with time. It may occur. The decrease in physical properties over time is particularly noticeable when general tap water or industrial water is used, due to the synergistic effect of the sulfite contained in the polymer and the trace components in the water used, such as chlorine and metals. This is probably because the main chain of the acrylamide polymer is rapidly cleaved.
[0014]
In contrast, in the present invention, the action of sulfite induces the acrylamide monomer to be a low toxicity compound such as a Michael adduct, and at the same time, the main chain of the acrylamide polymer is cleaved. Presumed to be suppressed by the presence of salts.
[0015]
Acrylamide polymers used in the present invention is a polymer obtained from a monomer mixture containing acrylamide monomer 30 mol% or more, are water soluble.
[0016]
Monomers copolymerizable with acrylamide monomers that can be added to the monomer mixture include methacrylamide; N, N-dialkylaminoalkyl (meth) acrylamide, N, N-dialkylaminoalkyl (meth) Acrylates and salts thereof; quaternary ammonium salts of N, N-dialkylaminoalkyl (meth) acrylamide and N, N-dialkylaminoalkyl (meth) acrylate; N-alkyl substituted (meth) acrylamides such as N-isopropylacrylamide; N, N-dialkyl-substituted (meth) acrylamides such as N, N-dimethylacrylamide; N-vinylpyrrolidone; N-vinyl (-N-alkyl) formamide; N-vinyl (-N-alkyl) acetamide; vinylpyridine, allylamine And salts thereof; Sulfonic acid and its salt; Acrylamide alkylsulfonic acid such as 2-acrylamido-2-methylpropanesulfonic acid and salts thereof; (Meth) acrylonitrile; (Meth) acrylic acid and salts thereof; Lower alkyl ester of (meth) acrylic acid Etc. can be illustrated.
[0017]
As the acrylamide polymer, a polymer modified by partial hydrolysis, methylolation, Mannich reaction, or the like during or after polymerization; a mixture with a water-soluble polymer, or the like can also be used.
[0018]
Moreover, a crosslinkable acrylamide polymer in which a polyfunctional monomer having two or more ethylenically unsaturated bonds such as N, N′-methylenebisacrylamide is copolymerized can also be used.
[0019]
Although the manufacturing method of the acrylamide type polymer used by this invention is not specifically limited, The aqueous solution polymerization using a normal radical polymerization initiator can be illustrated.
[0020]
Specifically, first, an aqueous solution containing 5% by mass or more, preferably 70% by mass or less, more preferably 50% by mass or less of a monomer mixture is prepared.
[0021]
Next, inorganic peroxide (persulfate, hydrogen peroxide, etc.) and / or organic peroxide (tertiary butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, etc.), tertiary amine, sulfite Or a redox initiator combined with a reducing agent such as ferrous salt; and / or azobisisobutyronitrile, 2,2'-azobis- (2-amidinopropane) dihydrochloride, 4,4'- An azo initiator such as azobis- (4-cyanovaleric acid) is added to the aqueous solution of the monomer mixture in the range of 0.0001% by mass to 0.4% by mass of the monomer mixture.
[0022]
Then, an acrylamide type polymer can be obtained by superposing | polymerizing at -10 degreeC or more and 100 degrees C or less. In general, the weight average molecular weight of the acrylamide polymer is 1000 or more and 50 million or less. In the use of a polymer flocculant, those of 1 million to 30 million are mainly used.
[0023]
Moreover, an acrylamide polymer can also be manufactured by photopolymerization using the photoinitiator which produces | generates an initiating radical with light as an initiator.
[0024]
Furthermore, as a production method other than aqueous solution polymerization, for example, an acrylamide polymer can be produced by emulsion polymerization or dispersion polymerization.
[0025]
Examples of the alkali metal salt of sulfurous acid for reducing the residual monomer used in the present invention include sodium salt and potassium salt, and sodium salt is preferable from the viewpoint of the effect of reducing monomer.
[0026]
The sulfite for reducing the residual monomer is obtained by mixing or spraying as an aqueous solution, impregnating a polymer powder with an aqueous sulfite solution, or adding a sulfite powder into an aqueous polymer solution. It is added in an optional step after the completion of the polymerization of the system polymer.
[0027]
For example, it can be added to the water-containing polymer before or during drying after completion of the polymerization, or to a granular or powdery polymer after drying. Moreover, it can also add to the gel-like substance containing the polymer aqueous solution after superposition | polymerization, a slurryed material, an emulsion liquid, or a dispersion liquid.
[0028]
The addition amount may be an amount suitable for achieving the target monomer concentration from the monomer concentration present at the time of addition, but the residual unit contained in the acrylamide polymer obtained by usual polymerization. Taking the amount of the monomer into consideration, the content is set to 0.1% by mass or more and 15% by mass or less of the acrylamide polymer . The content of sulphite least 0.5 mass% of acrylamide polymer is preferred, preferably 10 wt% or less. If the content of sulfite is within the above range, the acrylamide monomer can be sufficiently reduced without impairing the properties of the acrylamide polymer.
[0029]
Manganese salts used in the present invention include manganese chloride, manganese fluoride, manganese bromide, manganese sulfate, manganese nitrate, manganese phosphate, manganese formate, manganese acetate, manganese oxalate, manganese benzoate, manganese acrylate, etc. Can be illustrated.
[0030]
In order to sufficiently suppress the decrease in the degree of polymerization of the acrylamide polymer, the content of the manganese salt is manganese and is 15 mass ppm to 1000 mass ppm of the acrylamide polymer . The content of manganese salts, in order to prevent the above 30 ppm by weight of the acrylamide polymer is preferably in the amount of manganese decreases the other properties of the acrylamide polymer is preferably not more than 500 mass ppm, 300 mass ppm The following is more preferable.
[0031]
Examples of the method of adding manganese salts include a method of mixing or spraying as an aqueous solution, a method of impregnating a polymer powder with an aqueous solution of manganese salts, a method of adding a powder of manganese salts into a polymer aqueous solution, and the like. It can be added in any step after the completion of the polymerization of the system polymer.
[0032]
For example, it can be added to the water-containing polymer before or during drying after completion of the polymerization, or to a granular or powdery polymer after drying. Moreover, it can also add to the gel-like substance containing the polymer aqueous solution after superposition | polymerization, a slurryed material, an emulsion liquid, or a dispersion liquid.
[0033]
In particular, as a method for producing an acrylamide polymer composition powder,
A polymerization step of preparing a gel aqueous solution containing an acrylamide polymer from an aqueous solution containing an acrylamide monomer and a polymerization initiator;
Adding a sulfite and a manganese salt to the resulting gel aqueous solution to prepare a salt-containing gel aqueous solution;
A step of drying the obtained salt-containing gelled aqueous solution;
Can be exemplified.
[0034]
In general, the drying conditions are 40 ° C. or more and 150 ° C. or less and 0.5 hours or more and 30 hours or less.
[0035]
Since the acrylamide polymer composition produced by the above method or the like contains sulfite, the content of the remaining acrylamide monomer is 10 mass ppm or less, more preferably 5 mass ppm of the acrylamide polymer. It can be as follows.
[0036]
In addition, since the acrylamide polymer composition produced by the above method or the like contains manganese salts, the degree of polymerization of the acrylamide polymer is suppressed from being reduced in the drying step or the like. For this reason, the viscosity of 4 mass% saline solution with an acrylamide polymer content of 1 mass% can be 2000 mPa · s or more. Further, from the viewpoint of operability, it is preferable to adjust the degree of polymerization of the acrylamide polymer so that the viscosity of the aqueous solution is 10,000 mPa · s or less.
[0037]
The viscosity of the aqueous polymer solution can be measured as a Brookfield viscosity using a B-type viscometer (rotor rotational speed 6 rpm, rotor No. 2).
[0038]
Furthermore, when the powder of the acrylamide polymer composition is dissolved in 0.7 mass ppm chlorinated water so that the content of the acrylamide polymer is 0.5 mass%, the action of manganese salts causes a lapse of time. It is possible to prevent the viscosity of the aqueous solution from being substantially reduced. It should be noted that the viscosity of the aqueous solution does not substantially decrease when the polymer aqueous solution is allowed to stand at 45 ° C. for 16 hours, and the viscosity retention defined by the following formula is preferably 90% or more, more preferably 95%. Means more than%;
Viscosity retention (%) = 100 × (viscosity after standing) / (viscosity before standing).
[0039]
In the acrylamide polymer composition of the present invention described above, the content of the remaining acrylamide monomer is reduced, and the viscosity decrease with time of the aqueous acrylamide polymer solution is suppressed. Therefore, the acrylamide polymer composition of the present invention is suitably used in the fields of polymer flocculants, papermaking agents, soil conditioners, oil recovery agents, drilling mud thickeners, polymer absorbers, and the like. Can be used.
[0040]
【Example】
The present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention. Unless otherwise specified, “parts” and “%” mean “parts by mass” and “% by mass”, respectively, and commercially available high-purity products were used.
[0041]
(Evaluation methods)
The characteristics of the obtained acrylamide polymer composition were evaluated by the following methods.
[0042]
(A) Residual monomer concentration (ppm)
3 g of the acrylamide polymer composition powder is added to 30 mL of a mixed solution of methanol and water (methanol / water = 80/20 by volume), shaken at 30 ° C. for 16 hours, and remains in the acrylamide polymer composition. Acrylamide monomer was extracted. Thereafter, the extract was analyzed by high performance liquid chromatography, and the residual acrylamide monomer content of the acrylamide polymer composition was quantified.
[0043]
(I) Viscosity of aqueous acrylamide polymer solution (mPa · s)
An aqueous solution containing 1% of the polymer and 4% of sodium chloride was prepared, and the Brookfield viscosity of this aqueous solution was measured using a B-type viscometer (rotor rotational speed 6 rpm, rotor No. 2).
[0044]
(C) Viscosity retention (%)
The powder of the acrylamide polymer composition is dissolved in water (model tap water) containing 0.7 mass ppm of chlorine so that the effective polymer content is 0.5%, and immediately after that, the viscosity of the aqueous polymer solution is as described above. Measured according to Thereafter, the aqueous polymer solution was allowed to stand at 45 ° C. for 16 hours, and the viscosity was measured again.
[0045]
Based on the obtained results, the viscosity retention (%) of the aqueous polymer solution was calculated according to the following formula as an index of the change in the viscosity of the aqueous polymer solution over time;
Viscosity retention (%) = 100 × (viscosity after standing) / (viscosity before standing).
[0046]
Examples 1 and 2 Acrylamide polymer compositions 1 and 2
A monomer aqueous solution in which 21 parts of acrylamide monomer and 4 parts of sodium acrylate were dissolved in 75 parts of pure water was placed in a Dewar bottle, the inside of the system was replaced with nitrogen, and then at pH 6 and 10 ° C. as a redox initiator. Add 0.0003 parts of butyl hydroperoxide, 0.0004 parts of sodium nitrite and 0.04 parts of 2,2′-azobis- (2-amidinopropane) dihydrochloride as an azo initiator. The polymer was allowed to stand for 30 minutes after the temperature rose due to polymerization and reached the maximum temperature, and the resulting hydropolymer gel was extracted from the Dewar bottle to obtain a gel-like product containing an acrylamide polymer. A manganese sulfate aqueous solution was added to the gel-like material and mixed so that the amount of manganese was 0.005% (Composition 1) or 0.01% (Composition 2) of the acrylamide polymer. A sodium sulfite aqueous solution was added to and mixed with the resulting gel-like material containing manganese sulfate so as to be 5% of the acrylamide polymer. Thereafter, the gel-like material was dried at 60 ° C. for 16 hours to obtain an acrylamide polymer composition 1 or 2 powder.
[0047]
The properties of the obtained powder were evaluated, and the results are shown in Table 1. From this, it was found that the content of the residual monomer was low and the decrease in the aqueous solution viscosity with time was small.
[0048]
(Example 3) Acrylamide polymer composition 3
A powder of the acrylamide polymer composition 3 was produced in the same manner as in the case of the acrylamide polymer composition 2 except that sodium sulfite was changed to sodium hydrogen sulfite.
[0049]
The properties of the obtained powder were evaluated, and the results are shown in Table 1. From this, it was found that the content of the residual monomer was low and the decrease in the aqueous solution viscosity with time was small.
[0050]
(Comparative Example 1) Acrylamide polymer composition 4
A powder of acrylamide polymer composition 4 was prepared in the same manner as in acrylamide polymer composition 1 without adding manganese sulfate and sodium sulfite.
[0051]
The properties of the obtained powder were evaluated, and the results are shown in Table 1. From this, it was found that the content of the residual monomer was high although the decrease in the viscosity of the aqueous solution with time was small.
[0052]
(Comparative Examples 2 and 3) Acrylamide polymer compositions 5 and 6
In the same manner as in the case of the acrylamide polymer composition 1, acrylamide was added except that only sodium sulfite (Composition 5) or only sodium hydrogen sulfite (Composition 6) was added to be 5% of the acrylamide polymer. A powder of the polymer composition 5 or 6 was produced.
[0053]
The properties of the obtained powder were evaluated, and the results are shown in Table 1. From this, it was found that although the content of the residual monomer was low, the initial polymer aqueous solution viscosity decreased greatly and the aqueous solution viscosity decreased with time.
[0054]
(Comparative Example 4) Acrylamide polymer composition 7
Except for the addition of manganese sulfate, sodium sulfite and sodium hydroxide were added in the same manner as in acrylamide polymer composition 1 except that sodium sulfite and sodium hydroxide were added to 5% and 0.5% of the acrylamide polymer, respectively. Thus, a powder of the acrylamide polymer composition 7 was produced.
[0055]
The properties of the obtained powder were evaluated, and the results are shown in Table 1. From this, it was found that the content of the residual monomer was low, but the aqueous solution viscosity greatly decreased with time.
[0056]
[Table 1]

[0057]
【The invention's effect】
As is clear from the above explanation, by adding manganese salts and sulfites to the acrylamide polymer, the content of the remaining acrylamide monomer is reduced, and the viscosity decrease with time of the aqueous acrylamide polymer solution is suppressed. can do.

Claims (4)

An acrylamide polymer composition comprising an acrylamide polymer, a manganese salt, and one or more sulfites selected from the group consisting of alkali metal sulfites, alkali metal hydrogen sulfites, and alkali metal pyrosulfites. Te, acrylamide-based polymer obtained from a monomer mixture containing acrylamide least 30 mol%, Ri soluble der, the content of manganese salts, manganese content, more than 15 mass ppm of acrylamide polymer 1000 mass ppm or less, the content of sulfite, acrylamide polymer composition characterized der Rukoto 0.1 wt% to 15 wt% of the acrylamide polymer.  The acrylamide polymer composition according to claim 1, wherein the content of the remaining acrylamide monomer is 10 mass ppm or less of the acrylamide polymer. The viscosity of a 4% by mass salt solution having an acrylamide polymer content of 1% by mass is 2,000 mPa · s or more and 10,000 mPa · s or less, and the viscosity does not substantially decrease with time. 2. The acrylamide polymer composition according to 2. A polymerization step for preparing a gel aqueous solution containing an acrylamide polymer from an aqueous solution containing an acrylic monomer containing 30 mol% or more of an acrylamide monomer and a polymerization initiator, and sulfite is added to the gel aqueous solution with acrylamide A salt-containing gel aqueous solution is added in the range of 0.1 mass% to 15 mass% of the polymer and manganese salt in a range where the manganese amount is 15 mass ppm to 1000 mass ppm of the acrylamide polymer. A method for producing a powdery acrylamide polymer composition, comprising a step of preparing and a step of drying the salt-containing gelled aqueous solution.