JP2860554B2 - Method for producing cationic acrylamide polymer and use thereof - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a cationic acrylamide polymer mainly used as a paper strength enhancer and a flocculant, and more specifically to acrylamide. The present invention relates to a method for producing a cationic acrylamide-based polymer by performing a Hoffman decomposition reaction on a polymer at a high temperature for a short time.

[Conventional technology and its problems]

Conventionally, as a cationic acrylamide-based polymer (hereinafter, acrylamide-based polymer is simply referred to as polyacrylamide), there are Hoffman-decomposed polyacrylamide, Mannich-modified polyacrylamide, and a copolymer of a cationic monomer and acrylamide, and the like. It is used for various applications such as an enhancer and a polymer flocculant, or its use is being studied.

Among these, Hoffmann-degraded polyacrylamide has excellent characteristics not found in copolymers with Mannich polyacrylamide and cationic monomers, but its cationicity disappears with time in an aqueous solution. There is a problem of deterioration over time, and it has not been widely used.

Conventionally, various studies have been made to improve the point.
As one of these, there is an attempt to suppress the side-effect by suppressing the side reaction by performing the Hoffman decomposition reaction of polyacrylamide at a low temperature. In other words, it was pointed out in the Polymer Papers Vol. 33, No. 6, pp. 309-316, in 1976 that the conversion of polyacrylamide to amino groups easily occurs even at low temperatures due to the reaction promoting effect of adjacent groups. It is disclosed that it is desirable to carry out the reaction at a low temperature of about 25 ° C. or less in order to obtain high-performance aminated PAM in order to suppress side reactions (hydrolysis, lactam ring formation, etc.), depolymerization, etc. I have. Similarly, the superiority of performing the Hoffman decomposition reaction of polyacrylamide at low temperature is described in JP-A-61-200103, JP-A-58-152004, and JP-A-58-10.
8206, JP-A-57-165404, JP-A-55-6556, JP-A-52-165404
152493 and JP-A-51-122188.

However, according to studies by the present inventors, mere change of the Hoffman decomposition reaction at a low temperature does not improve the change over time to such an extent that it can be practically used. As another method, a hydroxyl-substituted compound having a cationic group introduced therein such as a quaternary ammonium salt or an N, N-dialkyl-substituted diamine, guanidine, polyamine, or the like during the Hoffman decomposition reaction is allowed to coexist, and an intermediate during the Hoffman decomposition reaction is provided. Japanese Patent Application Laid-Open Nos. 62-59602 and 61-1 describe the idea of reacting the substance with an isocyanate group which is a substance and preventing the change with time by incorporating the substance into a polymer.
20807, JP-A-57-192408, JP-A-56-144295, JP-A-5
4-145790 and JP-A-53-109594. However, according to the present inventors, it is a fact that satisfactory results have not been obtained even with such a method.

[Means for solving the problem]

In view of the above, the present inventors have conducted a detailed study of the Hoffman decomposition reaction of polyacrylamide.Unexpectedly, the Hoffman decomposition, which was not neglected at all, was performed at a high temperature in a specific range, and the reaction time was also surprising. It has been found that by setting the specific range to a very short time, it is possible to produce a cationic polyacrylamide having properties equivalent to or higher than that of Hoffman-decomposed polyacrylamide produced by a low-temperature reaction, and have reached the present invention.

That is, the present invention relates to: 1. An acrylamide-based polymer and a hypohalite are reacted at a temperature (T) in the range of 65 to 100 ° C. in an alkaline region of at least pH 11 and at a time (t) specified below. A) a method for producing a cationic acrylamide-based polymer, characterized in that the reaction is carried out in the following manner: e ^{15,150 / (273 + T)} × 2.5 × 10 ⁻²⁰ ≦ t (sec) ≦ e ^{15,150 / (273 + T)} × 10 ^-18 +30 (T is the reaction temperature) 2. Cationic acrylamide polymer obtained by the method described in 1 above, 3. After the reaction, adding a reducing agent to the reaction solution 4. The method for producing a cationic acrylamide polymer according to the item 1, wherein after performing the reaction, the reaction solution is cooled to a low temperature of 50 ° C. or lower. Production method, 5. After performing the reaction, the reaction solution was adjusted to pH 4-6. The method for producing a cationic acrylamide-based polymer according to the above item 1, wherein the reaction is adjusted to a range. 6. After the reaction, the reaction solution is added to alcohol to precipitate the polymer. 3. The method for producing a cationic acrylamide-based polymer according to 1) above, 7. The drainage improver containing the cationic acrylamide-based polymer as a main component according to 2) above, 8. The cationic acrylamide-based polymer according to 2 above Paper strength enhancer containing a polymer as a main component, 9. Polymer flocculant containing a cationic acrylamide-based polymer as a main component as described in 2 above, 10. Pulp using a cationic acrylamide-based polymer as a above 2 A paper strength enhancing method characterized by adding to the slurry; 11. a paper strength enhancing method characterized by applying the cationic acrylamide-based polymer described in 2 above to paper; 12. a paper strength enhancing method described in 2 above. 13. A method for improving drainage, which comprises using the cationic acrylamide polymer of the above in combination with an anionic resin, 13. using the cationic acrylamide polymer of the above 2 in combination with an anionic resin The paper-strengthening method characterized in that: 14. The aggregation method characterized by using the cationic acrylamide-based polymer described in 2 above in combination with an anionic resin.

According to the present invention, a completely new cationic polyacrylamide production system, which is different from the conventional one, becomes possible. By utilizing the production system, the problem of aging degradation of Hoffman-decomposed polyacrylamide can be avoided, and the invention can be applied to various fields. It became possible.

 Hereinafter, the present invention will be described in detail.

The acrylamide-based polymer (polyacrylamide) used in the present invention is a homopolymer of acrylamide (or methacrylamide) or a copolymer of acrylamide (or methacrylamide) with one or more unsaturated monomers copolymerizable therewith. It refers to a polymer, and further, a graft copolymer to a water-soluble polymer such as starch.

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

Further, as the ionic monomer, for example, acrylic acid,
Methacrylic acid, vinyl sulfonic acid, allyl sulfonic acid,
Acids such as methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl methacrylate, N, N -Diethylaminoethyl methacrylate, N, N-
Examples include amines such as dimethyl ahanoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, and N, N-dimethylaminopropyl acrylamide, and salts thereof.

As the lipophilic monomer, for example, N, N-di-n-
Propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide, Nn-hexylmethacrylamide, Nn-octylacrylamide, Nn-octylmethacrylamide, N-tert-octylacrylamide, N-dodecyl Acrylamide,
N-alkyl (meth) acrylamide derivatives such as Nn-dodecyl methacrylamide, N, N-diglycidyl acrylamide, N, N-diglycidyl methacrylamide,
N- (4-glycidoxybutyl) acrylamide, N-
(4-glycidoxybutyl) methacrylamide, N-
(5-glycidoxypentyl) 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, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, Examples include olefins such as propylene and butene, styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like. The amount of the unsaturated monomer used for the copolymerization may vary depending on the type of the unsaturated monomer and the combination thereof, but is generally in the range of 0 to 50% by weight.

As the water-soluble polymer for graft-copolymerizing the above-mentioned monomers, any of a natural polymer and a synthetic polymer can be used. Starch and oxidized starch of various origins as a natural system, carboxyl starch, dialdehyde starch, modified products such as cationized starch, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, alginic acid, agar, pectin, carrageenan, dextran, Pullulan, konjac, gum arabic, casein, gelatin and the like can be mentioned. Examples of the synthetic system include polyvinyl alcohol, polyvinyl ether, polyvinylpyrrolidone, polyethyleneimine, polyethyleneimine, 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.

Next, the above-mentioned monomers are polymerized to produce polyacrylamide, and the polymerization method is preferably radical polymerization. As the polymerization solvent, a polar solvent such as water, alcohol, and dimethylformamide can be used. However, since the Hoffman decomposition reaction is performed in an aqueous solution, aqueous polymerization is preferable. At that time, the monomer concentration is 2 to 30% by weight, preferably 5 to 30% by weight.
~ 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble, and is usually used after being dissolved in an aqueous monomer solution. Specifically, in the peroxide system, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl peroxide and the like can be mentioned. In this case, it can be used alone, but can also be used as a redox polymerizer in combination with a reducing agent. As the reducing agent, for example, sulfites, bisulfites, iron, copper, salts of lower ionization such as cobalt,
Organic amines such as N, N, N ', N'-tetramethylethylenediamine, and reducing sugars such as aldose and ketose can be mentioned.

As the azo compound, 2,2'-azobis-2-
Amidinopropane hydrochloride, 2,2'-azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof can be used. Furthermore,
Two or more of the above-mentioned polymerization initiators can be used in combination. In addition, when graft-polymerizing a water-soluble polymer, in addition to the above-described polymerization initiator as a polymerization initiator, it is also possible to use a transition metal ion such as ceric ion, ferric ion, and the like. You may use together with a polymerization initiator. The amount of the initiator added is 0.1 to 10% by weight, preferably 0.2 to 8% by weight, based on the monomer. In the case of the redox system, the amount of the reducing agent added is 0.1 to 10.0%, preferably 0.2 to 8.0% on a molar basis relative to the initiator.

The polymerization temperature is lower in the case of a single polymerization initiator and generally lower.
The temperature is 30 to 90 ° C., which is lower in the case of the redox polymerization initiator, and is generally 5 to 50 ° C. Further, it is not necessary to keep the same temperature during the polymerization, and it may be changed as the polymerization proceeds. Generally, the temperature rises due to polymerization heat generated as the polymerization proceeds. The atmosphere in the polymerization vessel at that time is not particularly limited, but it is preferable to replace the atmosphere with an inert gas such as a nitrogen gas in order to promptly carry out the polymerization. The polymerization time is not particularly limited.
About 20 hours.

Next, a Hoffman decomposition reaction of the polyacrylamide produced by the above method is performed. In that case, when the production of polyacrylamide as a raw material is carried out with an aqueous solution, the polyacrylamide can be used for the reaction as it is or after dilution as necessary. In the case of a graft copolymer, ungrafted polyacrylamide is also by-produced, but it is usually subjected to the reaction without separation.

The Hoffman decomposition reaction is carried out in the alkaline region, that is, by the action of hypohalite on the amide group of polyacrylamide in the coexistence of an alkaline substance, and hypohalous acid is hypochlorous acid or hypobromite. Acid and hypoiodic acid. Examples of the hypochlorite include the alkali metal or alkaline earth metal salts of such hypochlorous acid, and specifically, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, and hypochlorous acid. There are calcium chlorate, magnesium hypochlorite, barium hypochlorite and the like.
Similarly, hypobromite and hypoiodite include alkali metal or alkaline earth metal hypobromite and hypoiodite. It is also possible to generate a hypohalite by blowing a halogen gas into an alkaline solution.

On the other hand, examples of the alkaline substance include an alkali metal hydroxide, an alkaline earth metal hydroxide, and an alkali metal carbonate. Among them, an alkali metal hydroxide is preferable, and sodium hydroxide, potassium hydroxide, and hydroxide are preferable. Lithium and the like. The amount of the above-mentioned substance added to polyacrylamide is 0.05 to 2.0 mol, preferably 0.1 to 1.5 mol, based on the amide group in hypohalous acid, and 0.05 to 4.0 mol, preferably, 0.1 to 1.5 mol in the alkaline substance. 0.1 to 3.0 mol. The range of the alkaline region, ie, the pH range, is generally in the range of 11-14.

Under the above conditions, the concentration of polyacrylamide is approximately 0.
It is about 1 to 17.5% by weight, but when the reaction concentration is high, stirring becomes difficult and gelation is likely to occur.
Usually, it is preferably in the range of 0.1 to 10% by weight. Further, when the reaction concentration is less than 1% by weight, there is a problem that the reaction rate becomes slow, and so it is more preferably 1 to 10% by weight.

 On the other hand, the reaction temperature ranges from 65 to 100 ° C.

In the present invention, the Hoffman decomposition reaction is performed in a short time within the above-mentioned temperature range.The reaction time may vary depending on the reaction temperature and the polymer concentration in the reaction solution. In the case of about 1 to 10% by weight, it is enough within 65 minutes at 65 ° C and within several tens seconds at 80 ° C. Further, the higher the polymer concentration, the shorter the reaction time. In the above concentration range, the relationship between the reaction time and the reaction temperature is approximately between t calculated by the following two relational expressions.
If the reaction is carried out within the range, a suitable result can be obtained.

The cationic polyacrylamide produced under the above conditions has a cation equivalent measured by colloid titration at pH 2 in the range of approximately 0 to 10.0 meq / g, and the cation equivalent is controlled by the amount of hypohalite added. can do. Further, since the reaction is carried out in an alkaline region, the amide group is hydrolyzed and a carboxyl group is by-produced. The by-product amount is indicated by an anion equivalent measured by colloid titration at pH 10, and is generally in a range of 0 to 10.0 meq / g. The amount of the by-product can be controlled by the amount of the added alkaline substance.

Next, after carrying out the reaction under the above conditions, in the present invention, it is preferable to stop the reaction in order to suppress the progress of the side reaction. However, when used immediately after the reaction for the purpose described below, the reaction need not necessarily be stopped.

The reaction can be stopped by (1) adding a reducing agent,
Methods such as (2) cooling to lower the temperature, and (3) lowering the pH of the solution by adding an acid can be used alone or in combination. (1) is a method of inactivating remaining hypohalite and the like by reaction with a reducing agent. Examples of the reducing agent used include sodium sulfite, sodium thiosulfate, ethyl malonate, thioglycerol, triethylamine and the like. The amount of the reducing agent to be used is generally 0.005 to 0.15 times, preferably 0.01 to 0.10 times, the molar amount of the hypohalous acid used in the reaction. Generally, at the end of the Hoffman decomposition reaction, a compound having active chlorine such as unreacted hypohalite remains. If such a reaction solution is used as a paper strengthening agent, it may cause rust in a paper machine. Therefore, a reducing agent is usually used to inactivate active chlorine. However, the hypohalite reacts at an equimolar or less relative to the acrylamide unit mole number of the polymer, and when the reaction is performed at a high temperature, almost no unreacted hypohalite remains at the end of the reaction. . Therefore, if such conditions are adopted, it can be used as a paper strength agent without deactivating active chlorine using a reducing agent. The method (2) is a method of suppressing the progress of the reaction by cooling. Examples of the method include a method of cooling using a heat exchanger and a method of diluting with cold water. The temperature during cooling is usually 50 ° C or less, preferably 45 ° C or less, more preferably 40 ° C.
It is as follows. The lower part is not limited, but is preferably higher than the freezing temperature. In (3), the Huffman degradation reaction is stopped by lowering the pH of the solution at the end of the reaction, which usually shows an alkalinity of pH 12 to 13, using an acid, and at the same time, the progress of the hydrolysis reaction is suppressed. The pH at that time may be neutral or lower, and is preferably in the range of pH 4 to 6. Examples of the acid used for pH adjustment include mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, and organic acids such as formic acid, acetic acid, and citric acid. The reaction termination method can be appropriately selected from (1) to (3) depending on the reaction conditions, and these methods may be combined.

In the present invention, the reaction solution stopped by the above method can be used as an aqueous solution of the cationic polyacrylamide as it is, or is poured into a solvent in which the cationic polyacrylamide such as methanol of the aqueous solution is not dissolved to precipitate the polymer. And then dried to form a powder. In addition, the aqueous solution of the cationic polyacrylamide obtained by the above method can be stored in a tank and used as needed. The storage temperature at this time may be a low temperature that does not freeze the aqueous solution, and is preferably 10 to 15 ° C. However, when used within a relatively short period of time, it can be stored at room temperature and can be stored for about one month.

As described above, since the cationic polyacrylamide of the present invention can be produced in an extremely short time, on-site operation such as installing a production apparatus near a place (plant) to be used is possible. This is a major feature of the present invention. At this time, if the reaction is carried out under the condition that the amount of hypohalite used is lower than the amide group of polyacrylamide, it is possible to prevent free hypohalous acid ions from remaining in the solution. I can do it. In this case, it can be added to the pulp slurry or the like without stopping the reaction.

The cationic polyacrylamide produced according to the present invention can be applied to the fields where ordinary water-soluble cationic polymers are used. Among them, the fields of medicine and polymer flocculants used for papermaking are mainly used. And so on. In the field of paper chemicals, cationic polymers are used in various fields of paper manufacturing processes, but the cationic polyacrylamide produced by the method of the present invention is used in the step of making pulp, The addition thereof has a great effect for improving drainage for improving drainage of water, and for enhancing paper strength for enhancing mechanical strength of paper. These may be more effective when combined with a water-soluble anionic resin. The water-soluble anionic resin used at this time is a carboxyl group, a sulfonic acid group,
A water-soluble resin containing an anionic substituent such as a phosphate group or a salt thereof, such as an anionic acrylamide resin, an anionic polyvinyl alcohol resin, carboxymethyl cellulose, carboxymethylated starch, sodium alginate, etc. Can be mentioned.

The method of using the cationic polyacrylamide of the present invention for the purpose of improving drainage may be performed according to a conventionally known method. However, a feature of the method of the present invention is that the polyacrylamide and the hypohalite are reacted at a high temperature for a short time as described above, and then added immediately to the pulp slurry. Here, "immediately" means that the aqueous solution after the reaction is taken out of the pipe, transported in the same pipe without being transferred to the outside, and added to the pulp slurry. More specifically, the aqueous solution after the reaction may be directly added to the pulp slurry through a pipe, or a stock tank may be provided between them to temporarily stay there, and then the amount may be adjusted and added. The residence time of the reaction solution in the pipe may be within a range where the aqueous solution after the reaction does not deteriorate. However, if the length is too long, the size of the apparatus and piping for retaining the liquid becomes large, and the features of the present invention cannot be used. Therefore, in order to carry out the present invention suitably, it is preferable to add within 5 hours after the reaction, more preferably within 1 hour, even more preferably within 10 minutes.

Further, at that time, it may be diluted with water and added depending on the concentration of the cationic polyacrylamide after the reaction. The degree of dilution may vary depending on the type of pulp, the speed of papermaking, etc., but the concentration of the cationic polyacrylamide when added is generally 0.1 to 10% by weight, preferably 0.5 to 5% by weight, more preferably Is 0.8 to 2% by weight. At this time, the cationic polyacrylamide of the present invention can be used alone, but if necessary, it is also preferable to carry out papermaking in combination with a sulfate band, an anionic resin or the like.
These agents can be added in any order or simultaneously. Alternatively, the cationic polyacrylamide and the water-soluble anionic resin can be added after mixing at pH 9 or more. The addition ratio of the cationic polyacrylamide and the water-soluble anionic resin can be arbitrarily selected, and is in the range of 100: 0 to 10:90 in terms of the solid content weight. The amount of addition ranges from 0.005 to 3% by weight, preferably from 0.01 to 1% by weight, based on the dry solids weight of the pulp. The adding place may be any place before the wet sheet is formed, and it is usually better to add the place near the papermaking wire part. As described above, in the present invention, the solution immediately after the Hoffman decomposition reaction can be added to the pulp slurry without stopping the reaction or without stopping the reaction. In either case, the solution can be added without diluting, but if necessary, 0.1 to 10% of polymer solids
It is preferable to add after dilution with water.

The method of using the cationic polyacrylamide of the present invention for the purpose of a paper strength agent may be performed according to a conventionally known method. At this time, the cationic polyacrylamide of the present invention can be used alone, but if necessary, papermaking is performed in combination with a sulfate band, an anionic resin and the like. These agents can be added in any order or simultaneously. Further, it can be added after mixing the cationic polyacrylamide and the anionic resin at pH 9 or more. The addition ratio of the cationic polyacrylamide and the anionic resin can be arbitrarily selected, and is in the range of 100: 0 to 10:90 in terms of the weight of the solid content. The amount of addition is 0.01 to 5% by weight, preferably 0.05 to 2% by weight, based on the dry solid content of the pulp. The addition site can be added before the wet sheet is formed, but even after the wet sheet is formed, especially when manufacturing a laminated paper, it can be added by spray coating or roll coater coating. It is possible. In the present invention, the polyacrylamide is subjected to a Hoffman decomposition reaction at a high temperature for a short time to produce a cationic polyacrylamide, but surprisingly, the same reaction is carried out at a low temperature for a long time to obtain a cationic polyacrylamide. The present inventors have found that they show much better paper strength than polyacrylamide. The reason for this is not necessarily clear, but when the reaction is added to a pulp slurry or the like without performing a reaction stopping operation, the effect is particularly remarkable. It is considered that other functional groups generated due to the high temperature directly or indirectly contribute to the development of paper strength. Therefore, it is more preferable to add the compound without performing a reaction stopping operation. However, if the reaction is not stopped, deterioration occurs over time. In this case, it is preferable to add the compound immediately after the reaction. Here, "immediately" means that the aqueous solution after the reaction is taken out of the pipe, transported in the same pipe without being transferred to the outside, and added to the pulp slurry. More specifically, the aqueous solution after the reaction may be directly added to the pulp slurry through the pipe, or a stock tank is provided during that time, and temporarily stored there,
The amount may be adjusted and added. The residence time of the reaction solution in the pipe may be within a range where the aqueous solution after the reaction does not deteriorate. However, if the length is too long, the size of the apparatus and piping for retaining the liquid becomes large, and the features of the present invention cannot be used. Therefore, in order to carry out the present invention suitably, it is preferable to add within 5 hours after the reaction, more preferably within 1 hour, even more preferably within 10 minutes. Further, at that time, it may be diluted with water and added depending on the concentration of the cationic polyacrylamide after the reaction. The concentration varies depending on the type of pulp, the speed of papermaking, etc., and is not specified, but the concentration of the cationic polyacrylamide when added is generally 0.1 to 10% by weight, preferably 0.5 to 10% by weight.
-5% by weight, more preferably 0.8-2% by weight.

The paper manufactured by the above method is excellent in paper strength, specifically, burst strength, Z-axis strength, compressive strength, and the like. Therefore, when the method of the present invention is applied, when used for a material such as corrugated cardboard or newsprint in which waste paper occupies a high proportion, the effect is very large, and paper with high paper strength can be produced. Further, by applying the present invention not only to corrugated paper and newsprint but also to paper requiring strength, it becomes possible to produce paper having excellent paper strength.

On the other hand, in the field of polymer flocculants, the cationic polyacrylamide produced by the method of the present invention is discharged as domestic wastewater among various wastewaters, especially human waste / sewage, excess sludge discharged from biological treatment such as activated sludge, and the like. This is effective for coagulation and dehydration of organic suspensions. As a method of using the polymer coagulant of the present invention, when used for coagulation of wastewater or the like, the amount of addition is 0.01 to 1,000 ppm in solids with respect to the wastewater,
Preferably it is 0.1 to 100 ppm, and it can be applied to either the coagulation sedimentation method or the pressure flotation method. Also aggregated sediment,
When used as a dehydrating agent for sludge, the amount of addition is 0.01 to 50% by weight, preferably 0.2 to 10% by weight, based on the dry solid content of sludge, and the addition method is usually the precipitation in a coagulation tank. Add the polymer flocculant aqueous solution to the material, sludge, etc., stir,
Alternatively, the two are directly mixed in a pipe to form flocculated floc, and then filtered and dewatered. As a dehydration method, vacuum dehydration, centrifugal dehydration using a decanter or the like, capillary dehydration, pressure dehydration using a screw press dehydrator, a filter press dehydrator, a belt press dehydrator, or the like can be applied.

Further, in addition to the above-mentioned uses, the present invention can be applied to various fields such as water-based paints, water-based films, microcapsules, petroleum mining and recovery agents, adhesives, fiber treatment agents, dyeing processing aids, and pigment dispersants.

〔The invention's effect〕

The cationic polyacrylamide obtained by the method of the present invention is not only obtained in a short period of time, but also exhibits excellent action and effect when applied in various industrial applications. This has been done and is clear from the examples described later.

Although it is a bellows, the method of the present invention can produce a cationic polyacrylamide which is extremely excellent in quality in a short time reaction at a high temperature within a specific range, so that it is needless to say that the method has the following effects. .

(1) Since the reaction time is extremely short, the weight of the reaction apparatus can be reduced.

(2) Since the reaction apparatus can be miniaturized, the reaction apparatus can be installed at a site where cationic polyacrylamide is used, and the reaction can be performed on-site.

(3) By simply changing the composition of the reaction solution, a cationic polyacrylamide having a changed degree of cationicity can be produced in a short time.

(4) Further, paper itself having excellent paper strength can be manufactured.

〔Example〕

Hereinafter, the present invention will be described with reference to Examples. In the following,% means weight% unless otherwise specified.

Production Example 1 69.3 g of a 40% aqueous acrylamide solution, 221.9 g of distilled water and 6.5 g of isopropyl alcohol were placed in an 11 four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, and stirred. While replacing the inside with nitrogen gas
Heated to 45 ° C. Then, when 0.34 g of a 10% aqueous ammonium persulfate solution and 0.062 g of a 10% aqueous sodium bisulfite solution were added, the polymerization reaction started immediately, and the liquid temperature rose to 65 ° C. Thereafter, the temperature was maintained at 65 ° C. for 2 hours to obtain a polymer component of 10% and 25%.
An aqueous solution of polyacrylamide (PAM) having a Brookfield viscosity of 5,500 cps at ℃ was obtained.

Production Example 2 40% aqueous solution of acrylamide 63.9 g, N-vinylpyrrolidone 4.44 g, distilled water 229.5 g and isopropyl alcohol
Except for charging 2.16 g, in the same manner as in Production Example 1, polymer component 10%, Brookfield viscosity at 25 ° C. was 4,
An 800 cps N-vinylpyrrolidone copolymerized PAM aqueous solution was obtained.

Production Example 3 The same procedure as in Production Example 1 was carried out except that 62.7 g of a 40% aqueous solution of acrylamide, 4.91 g of N-acryloylpyrrolidine, 231.2 g of distilled water and 11.8 g of isopropyl alcohol were charged, and the polymer component was 10% and the Brook at 25 ° C. N-acryloylpyrrolidine copolymerized PA having a field viscosity of 3,050 cps
An M aqueous solution was obtained.

Production Example 4 40% aqueous solution of acrylamide 70.6 g, methacrylamide
1.78 g, distilled water 225.2 g and isopropyl alcohol 2.51 g
The polymer component was prepared in the same manner as in Production Example 1 except that
Brookfield viscosity at 10% at 25 ℃ 7,000cps
A methacrylamide copolymerized PAM aqueous solution was obtained.

Production Example 5 Acrylamide was placed in a 500 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube.
After dissolving 2 g and 1.67 g of styrene in 200 ml of dioxane, the mixture was heated to 70 ° C. while stirring and replacing the inside with nitrogen gas. Next, a benzene solution of azobisisobutyronitrile was added, and stirring was continued at 70 ° C. for 4 hours.
A precipitate formed. The precipitate was separated by filtration, dissolved in distilled water, and then poured into methanol for reprecipitation. This polymer component
The Brookfield viscosity of a 10% aqueous solution at 25 ° C is
It was 1,200 cps.

Production Example 6 In a 21-neck four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, 100 g of oxidized starch was dispersed in 900 g of distilled water, and heated to 70 to 90 ° C. After dissolution, it was cooled to 20 ° C. 50 g of acrylamide,
Distilled water (445 g), isopropyl alcohol (5.0 g) were added, and nitrogen gas was blown into the reaction solution for 30 minutes with stirring to sufficiently replace the system.After that, a 1N aqueous solution of cerium ammonium nitrate (4.5 g) in 1N-nitric acid was added, and the temperature was raised to 20 ° C. For 1 hour. After the completion of the reaction, the solution was adjusted to pH 6.5 to 7.0 with NaOH. The Brookfield viscosity of this 10% aqueous solution of the polymer component at 25 ° C. was 7,800 cps.

Example 1 The aqueous solution of the polyacrylamide polymer produced in Production Examples 1 to 6 was reprecipitated using 10 times the volume of methanol,
Powdered polyacrylamide-based polymer subjected to drying treatment 1.
0 g was dissolved in 14 g of distilled water. This solution was heated to 80 ° C., and while stirring, 1.77 g of a 12.5% sodium hypochlorite solution, 30
A mixed solution of 0.75 g of a 2% sodium hydroxide solution and 2.48 g of distilled water was added at one time. 5 seconds after the addition, the reaction mixture
After 0.1 to 0.2 g of an aqueous solution containing excess sodium sulfite was added to stop the reaction, colloid titration was performed with a 1 / 400N-potassium polyvinyl sulfonate aqueous solution using toluidine blue as an indicator to determine the degree of cationization. The results are shown in Table I.

Examples 2 to 3 The same operation as in Example 1 was carried out on the polyacrylamide-based polymer produced in Production Examples 1 to 6 at 80 ° C./60 seconds and at 65 ° C./60.
The reaction was performed under the reaction conditions of seconds, and the degree of cationization under each reaction condition was determined.

Comparative Examples 1-2 For the polyacrylamide-based polymers produced in Production Examples 1-6, the same operation as in Example 1 was performed at 20 ° C / 180 seconds, 20 ° C / 7.
The reaction was performed under the reaction conditions of 200 seconds, and the degree of cationization under each reaction condition was determined.

Examples 4 to 6 The aqueous solution of the polyacrylamide polymer produced in Production Example 1 was reprecipitated using 10 times the volume of methanol, and 1.0 g of the dried polyacrylamide polymer was dried and treated with 14 g of distilled water. Dissolved. The solution was kept at 80 ° C., and a mixed solution of 1.77 g of a 12.5% sodium hypochlorite solution, 0.75 g of a 30% sodium hydroxide solution, and 2.48 g of distilled water was added all at once with stirring. 5, 10, and 60 seconds after the addition, the degree of cationization was determined in the same manner as in Examples 1 to 3. The results are listed in Table II.

Comparative Examples 3 to 6 The aqueous solution of the polyacrylamide-based polymer produced in Production Example 1 was reprecipitated using 10 times the volume of methanol, and 1.0 g of the dried polyacrylamide-based polymer was converted to 14 g of distilled water. Dissolved. This solution was kept at 20 ° C., and a mixed solution of 1.77 g of a 12.5% sodium hypochlorite solution, 0.75 g of a 30% sodium hydroxide solution, and 2.48 g of distilled water was added all at once with stirring. Example 1, 5, 10, 60, 1,800 seconds after addition
The degree of cationization was determined in the same manner as in Examples 1 to 3.

Comparative Example 7 The aqueous solution of the polyacrylamide polymer produced in Production Example 1 was reprecipitated using 10 times the volume of methanol, and 1.0 g of the dried polyacrylamide polymer was dissolved in 14 g of distilled water. Was. The solution was kept at 80 ° C., and a mixed solution of 1.77 g of a 12.5% sodium hypochlorite solution, 0.75 g of a 30% sodium hydroxide solution, and 2.48 g of distilled water was added all at once with stirring. 1,800 seconds after the addition, the degree of cationization was determined in the same manner as in Examples 1 to 3.

Example 7 The aqueous solution of the polyacrylamide-based polymer produced in Production Example 1 was reprecipitated using 10 times the volume of methanol, and 1.0 g of the dried polyacrylamide-based polymer was dissolved in 34 g of distilled water. Was. This solution was kept at 80 ° C., and a mixture of a 12.5% sodium hypochlorite solution and a 30 wt% sodium hydroxide solution (molar ratio: 1: 1) shown in Table III was stirred.
2. Distilled water was added to make the total amount 5g). Ten seconds after the addition, the degree of cationization was determined in the same manner as in Examples 1 to 3. The anionization degree is 1 / 200N
A predetermined amount of methylglycol chitosan was added, and the pH was determined by back titration with a 1/400 N aqueous solution of potassium potassium polyvinylsulfonate using toluidine blue as an indicator.

Example 8 The aqueous solution of the polyacrylamide polymer produced in Production Example 1 was reprecipitated with 10 times the volume of methanol, and 1.0 g of the dried polyacrylamide polymer was dissolved in 34 g of distilled water. Was. This solution was kept at 80 ° C., and a mixture of 1.77 g of a 12.5% sodium hypochlorite solution and 30 wt% sodium hydroxide solution in a molar ratio as shown in Table IV was added under stirring (to a total of 5 g). (Distilled water was added) all at once. Ten seconds after the addition, the degree of cationization was determined in the same manner as in Examples 1 to 3, and the degree of anionization was determined in the same manner as in Example 7.

Papermaking Examples 1-3 Under the reaction conditions shown in Table V, the polymer concentration during the reaction was 2.
After adjusting the pH of the solution subjected to the Huffman decomposition reaction to pH 4.5 by the same method as in Examples 1 to 3 except that
Poured into 0 volumes of methanol to give a precipitate. The precipitate was filtered through a glass filter and then dried by a vacuum drier.
Drying was performed at 5 ° C. for 5 hours to obtain a white powder. This powder was dissolved in distilled water to form a 1% aqueous solution, which was referred to as a cationic polyacrylamide solution A. 480 ml of Canadian Standard Freeness (hereinafter referred to as CSF) obtained by beating cardboard waste paper, a pulp slurry with a concentration of 1.0% and a sulfuric acid band of 0.5% (based on dry weight,
And the mixture was stirred for 1 minute.
Next, commercially available anionic polyacrylamide (Hopron)
3150B, manufactured by Mitsui Toatsu Chemicals, Inc.) was added at 0.24% with respect to pulp and stirred for 1 minute. The cationic polyacrylamide solution A was then added to the pulp slurry at 0.16% by pulp. After the addition, stirring was continued for another minute. A part of this pulp slurry was measured for CSF in accordance with JIS P8121, and the rest was made with a TAPPI square sheet machine. Then 1
Dry for 2 hours in a blast dryer at 10 ° C, weighing 125 ± 3g / m2
Hand-made paper was obtained. For evaluation of handmade paper, see JIS P8
[Specific burst strength] and [Z-axis strength] were measured with an internal bond tester manufactured by Kumagai Riki according to 112. The results are shown in Table V.

Papermaking Comparative Example 1 Except that the reaction was carried out at 20 ° C. for 180 seconds,
A papermaking experiment was performed in the same manner as in Example 3 to obtain a handmade paper having a basis weight of 125 ± 3 g / m2. CSF, specific burst strength, Z-axis strength, and the like were measured in the same manner as in Papermaking Examples 1 to 3.

Papermaking Comparative Example 2 Papermaking Examples 1 to 7 except that the reaction was carried out at 20 ° C. for 7200 seconds.
A papermaking experiment was performed in the same manner as in Example 3 to obtain a handmade paper having a basis weight of 125 ± 3 g / m2. CSF, specific burst strength, Z-axis strength, and the like were measured in the same manner as in Papermaking Examples 1 to 3.

 These are summarized in Table V.

Agglomeration Experiment Example 1 10 g of the polyacrylamide-based polymer aqueous solution (solid content concentration: 10 wt%) and distilled water (20 g) produced in Production Example 1 were heated to 80 ° C., and stirred and stirred to obtain a 12.5% sodium hypochlorite solution (5.31 g, 30 g).
A mixed solution of 2.25 g of a 2% sodium hydroxide solution and 2.44 g of distilled water was added at one time. Ten seconds after the addition, 10 ml of a 212 mg aqueous sodium sulfite solution was added, and the pH was adjusted to 4.5 with concentrated hydrochloric acid.
After adjusting to, it was poured into about 10 times the volume of methanol to obtain a precipitate. After filtering the precipitate with a glass filter, the precipitate was dried at 40 ° C. for 6 hours using a vacuum drier to obtain a degree of cationization of 7.
98meq / g white powder I got This powder was dissolved in distilled water to form a 1% aqueous solution, which is referred to as a cationic polyacrylamide solution B. Night soil mixed sludge (digested sludge / excess sludge = 1/3, solid content 1.45
%) Into a 300 ml beaker, add 20 ml of the cationic polyacrylamide solution B, stir for 1 minute, and naturally filter the aggregated flocs through a Buchner funnel (filtration area 100 cm2,
Filter cloth 60 mesh tetron), and the amount of the gravity-dehydrated filtrate was measured to be 106 ml after 10 seconds, 108 ml after 20 seconds, and 11 ml after 30 seconds.
0 ml, 112 ml after 60 seconds. The water content of the dewatered cake obtained by centrifugally dewatering the flocculated floc after gravity dehydration at 3,000 rpm for 5 minutes was 88%.

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Claims (14)

(57) [Claims] 1. An acrylamide polymer and a hypohalite, at least in an alkaline region of pH 11 or more,
A method for producing a cationic acrylamide-based polymer, wherein the reaction is carried out at a temperature (T) in the range of 65 to 100 ° C. and within a time (t) specified below. e ^{15,150 / (273 + T)} × 2.5 × 10 ⁻²⁰ ≦ t (sec) ≦ e ^{15,150 / (273 + T)} × 10 ⁻¹⁸ +30 (T is the reaction temperature.) 2. A cationic acrylamide polymer obtained by the method according to claim 1. 3. The method for producing a cationic acrylamide-based polymer according to claim 1, wherein a reducing agent is added to the reaction solution after the reaction. 4. The method for producing a cationic acrylamide-based polymer according to claim 1, wherein the reaction solution is cooled to a low temperature of 50 ° C. or less after the reaction. 5. The method for producing a cationic acrylamide-based polymer according to claim 1, wherein the reaction solution is adjusted to a pH of 4 to 6 after the reaction. 6. The method according to claim 1, wherein after the reaction, the reaction solution is added to alcohol to precipitate a polymer.
3. The method for producing a cationic acrylamide-based polymer described in 1. above. 7. A drainage improver comprising the cationic acrylamide polymer according to claim 2 as a main component. 8. A paper strength enhancer comprising the cationic acrylamide polymer according to claim 2 as a main component. 9. A polymer flocculant comprising the cationic acrylamide polymer according to claim 2 as a main component. 10. A paper strength-enhancing method comprising adding the cationic acrylamide-based polymer according to claim 2 to a pulp slurry. 11. A method for enhancing paper strength, comprising applying the cationic acrylamide polymer according to claim 2 to paper. 12. A method for improving drainage, comprising using the cationic acrylamide polymer according to claim 2 in combination with an anionic resin. 13. A method for enhancing paper strength, comprising using the cationic acrylamide polymer according to claim 2 in combination with an anionic resin. 14. An aggregation method comprising using the cationic acrylamide polymer according to claim 2 in combination with an anionic resin.