JP3425992B2 - Analysis method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quantitatively analyzing a primary amino group generated when an acrylamide polymer solution is subjected to a Hoffman decomposition reaction. More specifically, when manufacturing a Hoffman degradation reaction product of an acrylamide polymer that is used as a paper strength enhancer or a flocculant, the primary amino group generated by detecting carbonate ions generated in the reaction process is quantitatively determined. To how to analyze. 2. Description of the Related Art Vinylamine is extremely unstable as a monomer and does not actually exist. Therefore, conventionally, a method for synthesizing a vinylamine-based polymer is as follows: (1) Hoffman decomposition reaction of an acrylamide-based polymer. How to manufacture,
(2) A method is known in which N-vinylformamide or N-vinylacetamide is produced by polymerization followed by hydrolysis. Among them, the Hoffmann decomposition reaction in which an amide group is reacted with hypohalous acid under alkaline conditions is a simple method of synthesizing a primary amino group from an amide group, and the reaction proceeds in substantially one step. It is industrially advantageous in that the reagents to be used are inexpensive and is widely used. [0003] Specific uses of the Hoffman decomposition reaction product of acrylamide-based polymer (hereinafter referred to as Hoffman decomposition PAM) include papermaking chemicals such as paper strength agents and drainage improvers, and flocculants used in wastewater treatment. Is raised. These polymers used as paper chemicals and flocculants have a primary amino group in the acrylamide polymer, show cationicity in an aqueous solution, and adsorb to negatively charged pulp fibers and sludge. It exerts an aggregating action and a paper strength enhancing action. One of the factors governing the performance of Hoffman-decomposed PAM is the amount of primary amino groups (expressed by the degree of cationization) generated by the Huffman-decomposition reaction, which is an important index in controlling the quality of products. . It is generally known that the degree of cationization is measured by a colloid titration method. For example, when measuring the degree of cationization of a cationic polymer, generally, a standard aqueous solution of polyvinyl potassium sulfate is dropped as a titration reagent using toluidine blue as an indicator, and the discoloration point from blue to magenta is measured. End point. This titration method is simple and is widely used as a method for measuring the degree of cationization of a water-soluble cationic polymer, but has the following disadvantages. (1) Disturbed by the presence of salts, especially polyvalent ions. (2) At the equivalent point, precipitation of the polymer complex may occur and titration is difficult. (3) It is easily affected by the polymer concentration at the time of analysis. [0005] Under such circumstances, the present inventors devised a method and an apparatus in which the Hoffmann decomposition reaction of an acrylamide polymer is performed at a high temperature in a short time and added immediately after production, and there is a problem in storage stability. The practical use of Hoffman decomposition PAM has been studied. This device can be used as a papermaking chemical or a flocculant immediately after Hoffman-decomposed PAM is produced in a short time and continuously, while maintaining high activity before the degradation reaction occurs. Performance of the Huffman-decomposed PAM is 10
You can now withdraw 0%. [0006] Such a continuous Hoffman decomposition PAM
It is necessary to control the quality of Hoffman-decomposed PAM to be produced continuously or intermittently in an apparatus for producing and adding Pam immediately after production. The degree of cationization is an important factor governing the performance, and in a continuous production apparatus, it is necessary to know the degree of cationization of the product in a short time after the reaction, and an analysis method with a fast response was indispensable. In the colloid titration method conventionally used, not only the disadvantages of the measurement method described above, but also problems such as poor workability and time required for titration, etc. Has become a major barrier to the transition. SUMMARY OF THE INVENTION An object of the present invention is to develop an analytical method capable of continuously and responsively measuring a primary amino group generated by a Hoffman decomposition reaction of an acrylamide polymer. Is what you do. Means for Solving the Problems The present inventors paid attention to carbonate ions generated by the Hoffman decomposition reaction, and quantified the amount of carbonate ions to determine the amount of primary amino groups generated by the Hoffman decomposition reaction. The present inventors have found that a method for indirectly quantifying is effective and completed the present invention. [0009] The Hoffmann decomposition reaction of an acrylamide polymer is a reaction in which a carbonate ion is eliminated from an amide group to form a primary amino group. Therefore, if carbonate ion can be quantified by any method, the amino group is indirectly converted. It is believed that it can be quantified. However, the primary amino group generated in the Hoffman decomposition reaction does not necessarily have an equivalent relation to the eliminated carbonate ion, such as forming a cyclic urea bond by causing a side reaction with an isocyanate group or the like as a reaction intermediate. Absent. Furthermore, it is considered that these side reactions are naturally affected by the reaction temperature, the reaction time, and the like. Therefore, the present inventors consider the above points, determine the ratio of side reactions at each temperature in advance by measuring the degree of cationization, measure the concentration of generated carbonate ions, and obtain a constant value derived from the side reaction ratio in the value. It has been found that it can be converted to the amount of formed amino groups only by multiplying by a coefficient. That is, the present invention provides an amide-based polymer solution
It is reacted with a hypohalite under pH10 or more alkaline region, by detecting the carbonate ion generated with the reaction
A method for quantifying the amount of generated primary amino groups, comprising:
Dissolved carbonate ions as carbon dioxide using electrodes
This is a method for quantitatively analyzing the generated primary amino group, which is characterized by detecting . Hereinafter, the present invention will be described in detail. The acrylamide polymer used in the present invention may be a homopolymer of acrylamide (or methacrylamide) or a copolymer of acrylamide (or methacrylamide) with one or more unsaturated monomers copolymerizable with acrylamide (or methacrylamide). Any polymer containing a graft copolymer to a water-soluble polymer such as starch or a water-soluble polymer and at least an acrylamide unit in the polymer may be used. Examples of the copolymerizable monomer include a hydrophilic monomer, an ionic monomer, and a lipophilic monomer, and one or more monomers can be used. 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-acryloylpyrroline, N-
Acryloylpiperidine, N-acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate,
Examples include hydroxypropyl acrylate, various methoxypolyethylene glycol (meth) acrylates, and N-vinyl-2-pyrrolidone. Examples of the ionic monomer include acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid,
Acids such as acrylamide-2-methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N,
Examples include amines such as N-dimethyl ahnoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, and N, N-dimethylaminopropyl acrylamide, and salts thereof. Examples of the lipophilic monomer include N, N-di-
n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide, Nn-hexylmethacrylamide, Nn-octylacrylamide, Nn-octylmethacrylamide, N-tert-
N-alkyl (meth) acrylamide derivatives such as octylacrylamide, N-dodecylacrylamide, Nn-dodecylmethacrylamide, N, N-diglycidylacrylamide, N, N-diglycidylmethacrylamide, N- (4-glycidyl) Xybutyl) acrylamide,
N- (4-glycidoxybutyl) methacrylamide, N
-(5-glycidoxybentyl) acrylamide, N-
N- such as (6-glycidoxyhexyl) acrylamide
(Ω-glycidoxyalkyl) (meth) acrylamide derivative, methyl (meth) acrylate, ethyl (meth)
(Meth) acrylate derivatives such as acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, Olefins such as ethylene, propylene, butene,
Styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like can be mentioned. 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 is generally in the range of 0 to 50% by weight. As the insoluble polymer for graft-copolymerizing the above-mentioned monomers, any of a natural type and a synthetic type can be used. As a natural system, starch and oxidized starch of various origins, metabolites such as carboxyl starch, dialdecin starch, cationized starch, cellulose derivatives such as methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, alginic acid, agar, pectin, carrageenan, Dextran, bullran, konjac, arabic gum, casein, gelatin and the like. As the synthesis system, polyvinyl alcohol,
Examples thereof include polyvinyl ether, polyvinyl pyrrolidin, polyethylene imine, polyethylene glycol, polypropylene glycol, polymaleic acid copolymer, polyacrylic acid, and polyacrylamide. The amount of the monomer added to the water-soluble polymer is in the range of 0.1 to 10.0 times based on the water-soluble polymer. In the present invention, the method is generally applied to an acrylamide polymer, but it goes without saying that other amide compounds can be used when carbonate ions can be detected in the Hoffman decomposition reaction. The Hoffman decomposition reaction is carried out by using a hypohalite in combination with an amide group of an acrylamide polymer in the presence of an alkaline substance. Examples of hypohalous acid include hypochlorous acid and hypobromite. And hypoiodic acid. Examples of the hypochlorite include metal hypochlorite or alkaline earth metal salts, specifically, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite,
There are calcium hypochlorite, magnesium hypochlorite, barium hypochlorite and the like. Similarly, hypobromite and hypoiodite include alkali metal or alkaline earth metal salts of hypobromite and hypoiodite. On the other hand, examples of the alkaline substance include an alkali metal hydroxide, an alkaline earth metal hydroxide, and an alkali metal carbonate. The amount of the above substances added to the acrylamide-based polymer is usually
0.05 to 2.0 mol, based on amide group for alkaline substances
0.05 to 4.0 mol. The pH at that time is generally in the range of 11-14. However, the present invention relates to the quantification of carbonate ions generated during the reaction, and there is no particular limitation on the use range of these additional substances in the present invention. Next, the temperature for the Hoffman decomposition reaction of the acrylamide polymer is in the range of 0 to 110 ° C. The reaction time depends on the reaction temperature.
Tens of hours, 2-5 hours at 20 ° C, seconds-minutes at 50 ° C,
At 80 ° C., the reaction is performed in the range of 1 to several tens of seconds, and the analysis according to the present invention is intended for the reaction performed under these conditions, but even if the conditions deviate from these conditions,
The analytical method according to the present invention can be used if a standard curve is prepared by defining reaction conditions in advance. Next, is a generation method for the determination of carbonate ions, gravimetric method conventionally volumetric method, an infrared absorption method, and other like are known. For the gravimetric method, (1) a method in which a certain amount of acid is added to a sample to measure the generated carbon dioxide gas with an alkali meter, and (2) the generated carbon dioxide gas is absorbed by a potash sphere or a soda-lime tube to increase the weight. And the like. The volumetric method, (1) Henberu method and gas volumetric method by Oruzatto method as (2) placed in a constant excess of Ba (OH) ₂ solution suitable gas absorption device, BaCO ₃ through a certain amount of the sample gas to There are a neutralization titration method in which immobilized and unreacted Ba (OH) ₂ is titrated with HCl standard solution using phenolphthalein as an indicator, and (3) a condensation vaporization method. The infrared absorption method
This method utilizes the fact that carbonate ions and carbon dioxide gas absorb infrared rays. In addition, quantitative analysis can be performed by a conductivity measurement method, a gas chromatography measurement method, or the like. In view of the above points, the inventors of the present invention have intensively studied various methods for quantifying carbon dioxide gas. As a result, (1) the method using a carbon dioxide gas electrode involves dissolving dissolved carbon dioxide gas in a liquid or gaseous phase. It is a simple and highly selective method to detect,
It has been found that it is more preferable to use this method. The carbon dioxide gas electrode is a composite electrode using a permeable membrane, and the amount of carbon dioxide that has passed through the membrane is detected by an internal pH electrode. In this detection method, it is necessary to gasify carbonate ions dissolved in the test solution, so that the pH of the solution is usually adjusted to 4 or less. The solution after the Hoffman decomposition is usually pH 11 to 14, and the acid is added to the solution to lower the pH to 4 or less, and then the measurement is performed. The acid used at this time is hydrochloric acid, sulfuric acid,
Mineral acids such as phosphoric acid and nitric acid; and organic acids such as formic acid, acetic acid and citric acid. Further, a method of quantifying the generated carbonate ion is described.
For example, there is a method using an infrared absorption spectrometer. The infrared absorption spectrometer uses the property of carbon dioxide to absorb electromagnetic waves near 2,350 and 670 cm ^-1 .The dissolved carbonic acid is made acidic, and if the solution is below the saturated concentration of carbon dioxide, it is heated or desorbed. It is vaporized by a pneumatic operation to determine the amount of carbon dioxide in the gas phase. This detection method cannot be detected in the state of carbonate ions because the absorption of water and the absorption based on the acrylamide polymer overlap in an aqueous solution. Therefore, it is necessary to gasify carbonate ions dissolved in the test solution,
The pH is adjusted by a method similar to the method using a carbon dioxide gas electrode. Since carbon dioxide gas has Raman activity, it can be quantified by measuring the absorption at 1,340 cm ⁻¹ appearing in the Raman spectrum. Since the primary amino group disappears by a side reaction or a aging reaction, the amount of carbon dioxide gas detected by a carbon dioxide electrode method or an infrared absorption method is larger than the amount of primary amino groups actually present. , It is necessary to correct the detection value. Since the correction equation differs depending on the reaction conditions and the storage state after the reaction, and cannot be expressed unconditionally, it is preferable to experimentally determine the correction equation in each manufacturing apparatus and manufacturing process. When a correction formula is experimentally obtained, a correlation formula may be established between the indicated value of the carbon dioxide gas electrode or the infrared absorption spectrophotometer and the degree of cationization obtained by colloid titration. Also,
Colloid titration has various problems as described above, and it is not possible to determine an accurate primary amino group.
It is desirable to determine using the R method or the colorimetric method. When the correction formula is determined by the colloid titration method, it is preferable to conduct the analysis in a dilute aqueous solution as much as possible in order to avoid the influence of salts and precipitates. Specifically, it is desirable to perform colloid titration analysis in an acidic solution (pH 2 or less) so that the Hoffman PAM concentration is 0.01% by weight or less. In general, if the reaction conditions (reaction temperature, reaction time, reaction concentration, etc.) are the same, a linear relationship is established between the indicated value of the sensor and the degree of cationization. Can be converted to the degree of cationization. When the reaction conditions are different, the relationship between the indicated value and the degree of cationization under each condition is checked in advance, and each data can be used for correction. In the colloid titration method conventionally used for cationic water-soluble polymers, the PVSK standard solution, which is an anionic polymer, is titrated, and the end point is determined by a change in color. Hoffman degradation products of the acrylamide-based polymer
Since insolubles of Hoffman and Hoffman decomposition products may precipitate, this method has many problems as a method for continuously measuring the degree of cationization. The analysis method of the present invention essentially consists in gasifying dissolved carbonate ions and measuring the concentration of carbon dioxide in the solution or gas. Therefore, not only can the problem of colloid titration, which has been a problem in the past, be solved, but also automation of analysis and continuous measurement can be easily performed. EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not necessarily limited to the following examples. The percentages are by weight unless otherwise specified. Example 1 As shown in FIG. 1, a system composed of three piston type laboratory pumps, a mixer, and a diaphragm type carbon dioxide sensor (manufactured by Toa Denpa Kogyo Co., Ltd.) was prepared. The Hoffman decomposed product (H-PAM) of polyacrylamide (PAM) was used after reaction at 70 ° C. for 60 seconds. When the Hoffman decomposition rate is changed, the amount of sodium hypochlorite and caustic soda added to PAM changes, so that the concentration of H-PAM varies depending on the decomposition rate. Therefore, in the following examples, the H-PAM concentration after the reaction was 4 to 5%. The amounts of the diluting water and the 1N-sulfuric acid aqueous solution flow at a fixed rate with respect to the H-PAM, and the H-PAM concentration in the cell of the carbon dioxide gas sensor is 0.
The liquid temperature was adjusted to 25 ° C. at 3% or less. At this time, no formation of a precipitate was observed. The assay of the degree of cationization of H-PAM was performed by a colloid titration method. Colloid titration was performed by diluting the H-PAM concentration to 0.1% or less and using 1/400 N-PVSK at pH2.
The indicated value of the sensor was corrected to the H-PAM concentration of 0.2%, and the correlation with the degree of cationization determined by the colloid titration method was observed. The results are shown in Table 1 and FIG. [Table 1] As shown in FIG. 2, it has been found that there is a good correlation between the concentration of carbon dioxide and the degree of cationization determined by colloid titration. It has proven to be an effective means of analysis. Therefore, conventionally, a simple method for analyzing the cation group in H-PAM was limited to the colloid titration method, but an effective means for newly measuring the degree of cationization by the method shown in the present invention is provided. It was found. Further, by setting up the system as shown in the examples, continuous H-formation was difficult because the formation of a precipitate and the detection of the end point, which were conventionally disadvantages of colloid titration, were indispensable. PA
The degree of cationization of M can be measured. Thus, the analysis method of the present invention can be incorporated into the above-mentioned production line or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of a system for measuring the degree of cationization of the present invention.
It is an example. FIG. 2 is an example of an assay diagram of a cationization degree measurement monitor system.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroshi Ito               1190-3 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa               Ito Pressure Chemical Co., Ltd.                (56) References Dictionary of Chemistry 8 Compact Edition, Kyoritsu Publishing,               February 15, 1964, p. 703

Claims (1)

(57) [Claims 1] An amide polymer solution is reacted with a hypohalite under an alkaline range of pH 10 or more, and carbonate ions generated by the reaction are detected and formed. Primary amino
This is a method for quantifying the amount of base, and uses a carbon dioxide gas electrode to convert dissolved carbonate ions into carbon dioxide.
A method for quantitative analysis of a generated primary amino group, characterized in that the primary amino group is formed.