JP2005255749A - Composition containing amphoteric polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition exhibiting various excellent flocculating performances on various sludge and paper making systems, particularly a composition functioning as an excellent polymer flocculant, and to provide a sludge-dehydrating agent exhibiting excellent dehydrating performances, particularly a granulating property, on various sludge. <P>SOLUTION: The composition comprises two kinds of water-soluble amphoteric polymers having a cationic monomer unit, an anionic monomer unit, and a long-chain hydrophilic group-bearing monomer unit, the long-chain hydrophilic group being in a grafted state, where the ratio of the cationic monomer unit to the anionic monomer unit in the amphoteric polymer satisfies expressions (1)-(3): Ca<SB>1</SB>/An<SB>1</SB>≥1 (1); Ca<SB>2</SB>/An<SB>2</SB>≥1 (2); and ¾(Ca<SB>1</SB>-An<SB>1</SB>)-(Ca<SB>2</SB>-An<SB>2</SB>)¾≥1.5 (3). In the expressions, Ca<SB>1</SB>and An<SB>1</SB>are the molar number of the total cationic monomer units and the total anionic monomer units, respectively, based on 100 mole of the total of the constituting monomer units of the amphoteric polymer 1, and Ca<SB>2</SB>and An<SB>2</SB>are the same molar numbers in the amphoteric polymer 2 as above. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a composition containing a water-soluble amphoteric polymer, and the composition of the present invention is useful as a polymer flocculant, and is particularly awarded in various technical fields such as a sludge dehydrating agent and a yield improving agent. It can be used.

Conventionally, water-soluble polymers, particularly high molecular weight water-soluble polymers, have been used in various technical fields as polymer flocculants, yield improvers, paper strength enhancers, and thickeners.
Examples of such water-soluble polymers include anionic monomers such as (meth) acrylates, cationic monomers such as dimethylaminoethyl (meth) acrylate quaternary salts, and nonionic properties such as (meth) acrylamides. Each homopolymer obtained by polymerizing monomers, a copolymer of an anionic monomer and a nonionic monomer, a copolymer of a cationic monomer and a nonionic monomer, In addition, polymers having ionic properties, such as copolymers with cationic monomers, anionic monomers, and nonionic monomers are known.

By the way, a cationic polymer flocculant is often used alone for sludge dehydration.
However, in recent years, due to the increase in sludge generation and sludge properties, conventional cationic polymer flocculants are limited in terms of sludge throughput, dewatered cake moisture content, SS recovery rate, etc. Since the state is not always satisfactory and it is required to improve these points, various amphoteric polymer flocculants and dehydration methods using them have been studied.
For example, a sludge dehydration method in which a cation-rich amphoteric polymer flocculant having a specific ion equivalent is added to an organic sludge having a pH of 5 to 8 to which an inorganic flocculant not containing inorganic sludge is added (Patent Document 1), and a pH of 5 Sludge dewatering method (Patent Document 2) using acrylate-based cationic polymer flocculant and amphoteric polymer flocculant in combination with organic sludge of ~ 8, adding inorganic flocculant to sludge, and setting pH to less than 5 , A dehydration method of adding an anion-rich amphoteric polymer flocculant having a specific composition (Patent Document 3) and an organic wastewater treatment method of sequentially adding an inorganic flocculant, an anionic polymer and a cation-rich amphoteric polymer flocculant to the wastewater (Patent Document 4) and the like are known.

Further, as a method other than using an amphoteric polymer flocculant, attempts have been made to impart hydrophobicity to the polymer.
For example, a method in which a terminal (meth) acrylate type polyalkylene oxide oligomer having an alkylene oxide skeleton having 1 to 5 repeats, and a polymer comprising (meth) acrylamide and a cationic monomer unit is used as a flocculant (Patent Literature) 5) Hydrophobic having a solubility in water of 1 g or less, such as a cationic monomer, an anionic monomer, and a water-soluble nonionic monomer and, for example, (meth) acrylic acid alkyl ester having 8 or more carbon atoms And a method of using an amphoteric polymer having an acrylic acid derivative as an essential component as a sludge dehydrating agent (Patent Document 6).

  On the other hand, conventionally, in the papermaking process, when the stock containing filler is diluted to the final concentration to be fed into the paper machine, or after dilution, a yield improver is added, and the pulp and white water from the paper machine into the white water is added. Suppresses filler outflow and improves yield.

As the yield improver, a water-soluble polymer such as water-soluble high molecular weight polyethylene oxide or cationic polyacrylamide is usually used.
However, the yield improver containing these water-soluble polymers needs to use a relatively large amount of the yield improver for the purpose of further improving the yield, and as a result, a huge floc is generated. The paper has a problem of extremely deteriorating the formation of paper.
In order to solve this problem, a method called a dual system in which a cationic polymer and an anionic compound or polymer are used in combination has recently been highlighted. Typical examples include a method of adding an anionic inorganic compound such as bentonite after the addition of the cationic polymer (Patent Document 7), a method of adding an anionic colloidal silica after the addition of the cationic polymer, and the like. (Patent Document 8).

Japanese Patent Publication No. 5-56199 (Claims) Japanese Patent No. 2933627 (Claims) Japanese Patent Publication No. 6-239 (Claims) JP-A-6-134213 (Claims) JP-A-4-96913 (Claims) JP-A-11-156400 (Claims) JP-A-4-281095 (Claims) Japanese Patent No. 2945761 (Claims)

  However, although the sludge dehydrating agent comprising amphoteric polymers described in Patent Documents 1 to 4 has its own characteristics, it is not necessarily an effective method for the recent tendency to dewatering wastewater. It was difficult.

  In addition, the polymers disclosed in Patent Documents 5 and 6 that are considered good as flocculants and sludge dewatering agents have problems in the process of polymerizing these monomers. For example, gelation is likely to occur in the polymerization process, especially when producing a high molecular weight polymer, the entire system may gel, and if you try to avoid it, only low molecular weight can be obtained, The copolymerizability ratio of each monomer is greatly different, and there is a problem that it is difficult to obtain a copolymer according to the charged ratio of each monomer. As a result, the intended performance improvement effect cannot be obtained, and even if the intended copolymer is obtained, depending on the type of sludge to be treated, it cannot be fully effective. Have a problem.

  On the other hand, the yield improvers described in Patent Documents 7 and 8 are relatively excellent in the balance between the yield rate and the paper texture, but the level is still insufficient. Since the retention improver needs to be used in combination with two liquids, there is a problem that the method of use is complicated, such as the addition location of each agent, the timing of addition, and the balance of the addition amount in the papermaking process. It was a thing.

In order to solve the above-mentioned problems, the present inventors cut a polymer flocculant composed of a composition containing two amphoteric polymers having different ion equivalents (Patent Document 9) and a specific ethylenically unsaturated group. A novel high molecular weight water-soluble polymer having a polyalkylene oxide oligomer at the terminal as an essential constituent monomer has been proposed (Patent Document 10).
These water-soluble polymers and polymer flocculants have excellent performance to solve the above problems, but may be insufficient in applications where further sludge dewatering performance and yield improvement performance are required. there were. In particular, depending on the sludge to be applied, the granulation property was insufficient.

  The inventors of the present invention are compositions that are excellent in various coagulation performance with respect to various sludges and papermaking systems, and in particular, in order to find a composition that is excellent as a polymer flocculant, and further dewatering performance for various sludges A sludge dewatering agent that excels in granulation, and a high yield rate, as well as a high yield rate of paper, and at the same time, a new yield improver that is easy to use. In order to find out, it was studied earnestly.

JP 2003-117309 A (Claims) JP 2003-321523 A (Claims)

As a result of various studies to solve the above problems, the present inventors have found that an amphoteric polymer grafted with a long-chain hydrophilic group, which is a cationic monomer unit and an anionic monomer The inventors have found that a composition using two or more amphoteric polymers having different unit ratios can solve the above-mentioned problems, and has completed the present invention.
In this specification, acrylic or methacryl is referred to as “(meth) acryl”, and acrylate or methacrylate is referred to as “(meth) acrylate”.
Hereinafter, the present invention will be described in detail.

1. Water-soluble amphoteric polymer The water-soluble amphoteric polymer (hereinafter simply referred to as amphoteric polymer) in the composition of the present invention is a monomer having a cationic monomer unit, an anionic monomer unit and a long-chain hydrophilic group. It is a polymer having a body unit and having the long-chain hydrophilic group in a graft form.
Each constituent monomer will be described below.

1-1. The cationic monomer is not limited as long as it has radical polymerizability, and specifically, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and diethylamino Dialkylaminoalkyl (meth) acrylate hydrochlorides such as 2-hydroxypropyl (meth) acrylate and tertiary salts such as sulfate, dialkylaminoalkyl (meth) acrylamide hydrochlorides such as dimethylaminopropyl (meth) acrylamide, and Tertiary salts such as sulfates, quaternary salts such as halogenated alkyl adducts such as methyl chloride adducts of dialkylaminoalkyl (meth) acrylates and aryl chloride adducts such as benzyl chloride adducts, and dialkylaminoalkyl ( (Meth) acrylamide methyl chloride Alkyl halide adducts of adducts and quaternary salts such as aryl halide adducts such as benzyl chloride adducts.
As the cationic monomer, a quaternary salt of dialkylaminoalkyl (meth) acrylate is preferable, and a halogenated alkyl adduct of dialkylaminoalkyl (meth) acrylate is more preferable.

1-2. As long as it has radical polymerizability also as an anionic monomer, an anionic monomer will not have a restriction | limiting, Specifically, unsaturated carboxylic acid and its salt are mentioned, More specifically, ( And (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid and the like.
As the anionic monomer, (meth) acrylic acid is preferable.

  Examples of the unsaturated carboxylic acid salt include ammonium salts, and alkali metal salts such as sodium and potassium.

1-3. The hydrophilic group in the monomer (hereinafter simply hydrophilic as monomer) units having a monomer length chain hydrophilic group having a long-chain hydrophilic groups, various functional groups can be used, polyalkylenes An oxide group is preferred.
Examples of the alkylene oxide constituting the polyalkylene oxide group include ethylene oxide, propylene oxide, and butylene oxide, and specific examples include a polyethylene oxide group, a polypropylene oxide group, and a polybutylene oxide group.
Moreover, as a polyalkylene oxide group, what has 2 or more types of polyalkylene oxide units in block shape, for example, a polyethylene oxide / polypropylene oxide block copolymer is mentioned.
Among these, those having a polypropylene oxide unit are preferable.

  In the polyalkylene oxide group, the number of repeating units of alkylene oxide is preferably 5 or more, more preferably 5 to 80. When the number is less than 5, when used as a flocculant or a dehydrating agent, sufficient dehydrating performance may not be exhibited. Further, when it exceeds 80, the amount of unpolymerized substances increases, and when used as a flocculant or a dehydrating agent, sufficient dehydrating performance may not be exhibited in the same manner.

  In addition, the structure of the polyalkylene oxide group terminal is not necessarily limited, but those having 1 to 8 carbon atoms such as methoxy group, ethoxy group, and butoxy group are gelated during polymerization. Therefore, the polymer can be stably produced, which is preferable for achieving the object of the present invention.

The hydrophilic monomer may be a compound having the polyalkylene oxide group and an ethylenically unsaturated group.
The ratio of the hydrophilic monomer unit in the amphoteric polymer is preferably 0.05 to 10 mol% with respect to the total amount of all the constituent monomer units excluding the hydrophilic monomer unit.
When this proportion is less than 0.05 mol%, the effect of improving the cohesive force due to having a long-chain hydrophilic group may not be observed. When the proportion exceeds 10 mol%, the resulting polymer is dissolved in water. May become insoluble.

As the amphoteric polymer, various polymers can be used as long as they have a cationic monomer unit and an anionic monomer unit and have the hydrophilic group in a graft form. What is obtained by copolymerizing a polyalkylene oxide oligomer having a saturated group at one end (hereinafter referred to as PRO oligomer), a cationic monomer, and an anionic monomer is preferable in terms of easy production.
Hereinafter, the PRO oligomer will be described.

1-3-1. As the PRO oligomer, one having an ethylenically unsaturated group represented by the following general formula (1) is preferable. When it is an ethylenically unsaturated group other than this, for example, a (meth) acryloyl group, it is easy to cause gelation during the production of the polymer, and even when gelation does not occur, the resulting polymer is water-soluble. May not be.

R ¹ CH═C (R ² ) −X− (1)

[In the above formula, R ¹ and R ² are hydrogen or an alkyl group having 1 to 3 carbon atoms, X is —R ³ O—, —O— or —R ⁴ NHCOO—, and R ³ and R ⁴ are An alkylene group having 1 to 4 carbon atoms, or -Ph- or -Ph-R ^5- , Ph is a phenylene group which may have a substituent, and R ⁵ is a carbon atom having 1 to 4 carbon atoms. An alkylene group; ]

The alkyl group having 1 to 3 carbon atoms of R ¹ and R ² is preferably a methyl group.
X is —R ³ O—, —O— or —R ⁴ NHCOO—, and when X is an ester bond other than these, for example, gelation is likely to occur during the production of the polymer. Even if it does not occur, the resulting polymer is not water-soluble. X is preferably —R ³ O— or —O—.

R ³ and R ⁴ are each an alkylene group having 1 to 4 carbon atoms or —Ph— or —Ph—R ⁵ —, Ph is an optionally substituted phenylene group, and R ⁵ is , An alkylene group having 1 to 4 carbon atoms.
The alkylene group for R ³ and R ⁴ may be linear or branched, and the phenylene group which may have a substituent is specifically a p-phenylene group. , M-phenylene group, and a mixture thereof, preferably p-phenylene group. Examples of the substituent for the phenylene group include an alkyl group and an alkyl ester group.
The alkylene group for R ⁵ may be linear or branched.
R ³ and R ⁴ are particularly preferably a methylene group or a phenylene group.

  Specific examples of the ethylenically unsaturated group represented by the general formula (1) include allyloxy, methallyloxy, allylethoxy, allylpropoxy, allylbutoxy, propenyloxy group, vinylbenzyloxy group and the like. Among these, an allyloxy group, a methallyloxy group, and a propenyloxy group are preferable because of excellent reactivity and easy availability.

Examples of the alkylene oxide constituting the main chain of the PRO oligomer include ethylene oxide, propylene oxide, and butylene oxide, and specific examples include polyethylene oxide oligomer, polypropylene oxide oligomer, and polybutylene oxide oligomer.
Moreover, what has 2 or more types of polyalkylene oxide units in block shape, for example, a polyethylene oxide / polypropylene oxide block oligomer, is mentioned.
Among these, those having a polypropylene oxide unit are preferable.

  In the PRO oligomer, the number of repeating units of alkylene oxide is preferably 5 or more, more preferably 5 to 80, for the same reason as described above.

  Further, the structure of the other end of the PRO oligomer is not necessarily limited, but those having 1 to 8 carbon atoms such as methoxy group, ethoxy group and butoxy group are the same as described above. Preferred for reasons.

  These PRO oligomers are prepared by esterification, etherification, urethanization reaction or the like of ordinary polyalkylene oxide oligomers and alcohols, isocyanato auto compounds, etc., but some are commercially available. Those commercially available products can also be used.

  The copolymerization ratio of the PRO oligomer and the monomer is preferably 0.05 to 10 mol% of the PRO oligomer with respect to the total amount of all monomers excluding the PRO oligomer for the same reason as described above. .

1-4. Other monomer The amphoteric polymer in the present invention essentially comprises the cationic monomer unit, the anionic monomer unit and the hydrophilic monomer unit. You may have.
As other monomers, water-soluble monomers are preferable, and nonionic monomers are more preferable. Examples of nonionic monomers include (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, and hydroxyethyl (meth) acrylate. As the nonionic monomer, (meth) acrylamide is preferable.

  As the amphoteric polymer, a monomer other than the water-soluble monomer may be copolymerized as necessary within a range not impairing the water solubility of the polymer. Specifically, for example, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) Examples include acrylonitrile and vinyl acetate.

1-5. Selection of Monomers The above-described monomers may be used alone or in combination of two or more.

In the present invention, as a nonionic monomer, the copolymerizability with a cationic monomer, an anionic monomer and a hydrophilic monomer can be improved, and the properties of the resulting polymer can be adjusted ( It is preferable to use meth) acrylamide together.
In this case, the ratio of (meth) acrylamide is preferably 5 to 80 mol% in all monomers.

  In the present invention, preferred combinations of monomers other than hydrophilic monomers include [1] tertiary or quaternary salt of dialkylaminoalkyl acrylate as the cationic monomer, and acrylic acid as the anionic monomer. A copolymer comprising acrylamide as a salt and a nonionic monomer, [2] a tertiary or quaternary salt of a dialkylaminoalkyl methacrylate as a cationic monomer, an acrylate and a nonionic monomer as an anionic monomer A copolymer comprising acrylamide as a monomer, and a tertiary or quaternary salt of a dialkylaminoalkyl methacrylate and a tertiary or quaternary salt of a dialkylaminoalkyl acrylate as a cationic monomer, an anionic monomer There are copolymers consisting of acrylate as the body and acrylamide as the nonionic monomer.

1-6. Production method As a production method of the amphoteric polymer, a cationic monomer, an anionic monomer and a hydrophilic monomer are used, preferably a cationic monomer, an anionic monomer and a PRO oligomer, What is necessary is just to superpose | polymerize and manufacture with a general polymerization method as a method of using these and the other polymerizable monomer used together together as needed, and obtaining a water-soluble polymer.
Examples of the polymerization method include aqueous solution polymerization, reverse phase emulsion polymerization, reverse phase suspension polymerization and the like, and aqueous solution polymerization and reverse phase emulsion polymerization are preferable in that they are easy to handle.

In the case of employing aqueous solution polymerization, a method in which a monomer is dissolved or dispersed in an aqueous medium and polymerized at 10 to 100 ° C. in the presence of a polymerization initiator can be mentioned. As the raw material monomer, one dissolved or dispersed in water is added to an aqueous medium.
In the case of employing reversed-phase emulsion polymerization, an aqueous solution containing a monomer and an organic dispersion medium containing a hydrophobic surfactant having an HLB of 3 to 6 are mixed by stirring and emulsified. A method of polymerizing in the presence at 10 to 100 ° C. to obtain a water-in-oil (reverse phase) polymer emulsion is mentioned. Examples of the organic dispersion medium include high-boiling hydrocarbon solvents such as mineral spirits.
The proportion of the monomer in the aqueous medium or the organic dispersion medium may be appropriately set according to the purpose, and is preferably 20 to 70% by mass.

Specific examples of the polymerization initiator in this case include persulfates such as sodium persulfate and potassium persulfate, organic peroxides such as benzoyl peroxide, 2,2′-azobis- (amidinopropane) hydrochloride, Azo compounds such as azobiscyanovaleric acid, 2,2′-azobisisobutyronitrile and 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], and peroxidation Examples thereof include a redox catalyst comprising a combination of hydrogen, sodium persulfate, sodium bisulfite, ferrous sulfate and the like.
In the case of aqueous solution polymerization, the polymerization can also be carried out by ultraviolet irradiation, and for example, polymerization can be carried out using a photopolymerization initiator such as ketal type or acetophenone type.

The amount of the polymerization initiator used may be determined according to the degree of polymerization and the viscosity of the target polymer, and is usually 10 to 20,000 ppm based on the total amount of all monomers and the polymerization initiator. It is preferable to use it.
The molecular weight of the amphoteric polymer can be adjusted by changing the type and ratio of the monomer and the polymerization initiator used together with a chain transfer agent.
Examples of the chain transfer agent in this case include thiol compounds such as mercaptoethanol and mercaptopropionic acid, and reducing inorganic salts such as sodium sulfite, sodium bisulfite and sodium hypophosphite.
The addition amount of the chain transfer agent is preferably 10 to 2000 ppm in the aqueous solution.

  The amphoteric polymer obtained by the aqueous solution polymerization is usually gel-like, chopped by a known method, dried at a temperature of about 60 to 150 ° C. with a band-type dryer, a far-infrared dryer, etc. The polymer is pulverized with a powder to obtain a powdery polymer, the particle size is adjusted, or an additive is added.

  When the amphoteric polymer obtained by water-in-oil (reverse phase) emulsion polymerization is actually used, a hydrophilic surfactant having a relatively high HLB is added, diluted with water, and phase-inverted. Used as a mold emulsion.

The preferred molecular weight of the amphoteric polymer in the present invention is preferably that having a 0.5% salt viscosity of 10 to 120 mPa · s, which is an index of molecular weight. For this purpose, 15 to 90 mPa · s is more preferable.
In addition, the 0.5% salt viscosity in this invention means the value measured according to the following method.

0.5% salt viscosity:
The polymer is dissolved in a 4% by mass sodium chloride aqueous solution to prepare a 0.5% by mass polymer solution. Using a B-type viscometer, the viscosity of the polymer solution after 5 minutes at a temperature of 25 ° C. and 60 rpm is measured.

2. Composition The composition of the present invention comprises two amphoteric polymers having different copolymerization ratios of a cationic monomer unit and an anionic monomer unit (hereinafter referred to as amphoteric polymer 1 and amphoteric polymer). 2), and the ratio of the cationic monomer unit and the anionic monomer unit in the amphoteric polymer satisfies the following formulas (1) to (3).

Ca ₁ / An ₁ ≧ 1 (1)
Ca ₂ / An ₂ ≧ 1 (2)
| (Ca ₁ −An ₁ ) − (Ca ₂ −An ₂ ) | ≧ 1.5 (3)

[However, in the above formulas (1) to (3), Ca ₁ and An ₁ are all cationic units when the total amount of all constituent monomer units in the amphoteric polymer ₁ is converted to 100 mol, respectively. Represents the number of moles of the monomer unit and the total anionic monomer unit, and Ca ₂ and An ₂ are the same as described above for the total cationic monomer unit and the total anionic monomer in the amphoteric polymer 2, respectively. Represents the number of moles of units. ]

That is, the amphoteric polymers 1 and 2 which are both cation-rich amphoteric polymers are used in combination, and the difference between the cationic monomer unit and the anionic monomer unit constituting them is large. It is a combination of small ones.
In this case, the amphoteric polymer 1 has a Ca ₁ / An ₁ of 1.2 to 40.0, and the amphoteric polymer 2 has a Ca ₂ / An ₂ of 1.2 to 40.0. preferable.
_{| (Ca 1 -An 1) -} (Ca 2 -An 2) | Preferred is from 1.5 to 40.0. If this value is less than 1.5, the high-performance aggregation performance as in the present invention cannot be exhibited.

  In the amphoteric polymers 1 and 2, the cationic monomer, the anionic monomer and the hydrophilic monomer are combined with the nonionic monomer as necessary so as to satisfy the monomer unit. It can be obtained by polymerization.

  The composition of the present invention can be produced by mixing the amphoteric polymers 1 and 2. Moreover, each component can also be added separately in the sludge dehydration and papermaking processes described later.

  As the amphoteric polymers 1 and 2, one type can be used, or two or more types can be used in combination.

  The proportion of the amphoteric polymer in the composition may be appropriately set according to the purpose, and the amphoteric polymer 1 is preferably 10 to 90% by mass and the amphoteric polymer 2 is preferably 90 to 10% by mass.

  The composition of the present invention is preferably used in the form of an aqueous solution. In this case, the concentration of the aqueous solution is preferably 0.05 to 0.5% by mass as the total amount of the amphoteric polymers used in the aqueous solution. Even when the amphoteric polymers to be used are used separately, each is preferably used in the form of an aqueous solution, and the same aqueous solution concentration as described above is preferable.

3. Uses The composition of the present invention can be applied to various uses. Examples thereof include polymer flocculants and thickeners for paints. Examples of the polymer flocculant include a papermaking agent in a papermaking process such as a sludge dehydrating agent and a yield improving agent.
The composition of the present invention is useful as a polymer flocculant, and particularly useful as a sludge dehydrating agent and a yield improving agent.
Hereinafter, the sludge dehydrating agent and the yield improving agent will be described.

3-1. Sludge dewatering agent and sludge dewatering method The composition of the present invention is particularly useful as a sludge dewatering agent.
As a composition, a powdery thing and a reverse phase emulsion are preferable. In actual use, when the composition is a powder, the powder is dissolved in water and used as an aqueous solution. When the composition is a reverse phase emulsion, it is diluted with water and phase-inverted and used as an oil-in-water emulsion.
In addition, when using a powdery sludge dehydrating agent, it may be used by mixing it with known additives such as sodium bisulfate, sodium sulfate and sulfamic acid as long as there is no adverse effect on the dehydration treatment. good.
The sludge dehydrating agent of the present invention (hereinafter sometimes referred to as a polymer flocculant) is applicable to various sludges, such as sewage, human waste, and general industrial wastewater such as food industry, chemical industry and pulp or paper industry sludge. Examples thereof include mixed sludge including organic sludge to be generated and coagulated sediment sludge.
The sludge dehydrating agent of the present invention can be preferably applied particularly to sludge having a low fiber content or sludge having a high surplus ratio. Specifically, it can be preferably applied to sludge having a surplus ratio of 10 SS% or more, more preferably 20 to 80 SS%. Further, it can be preferably applied to sludge having a fiber content of 10% or less.

  Specifically, the dewatering method using the sludge dewatering agent of the present invention is to add a sludge dewatering agent to the sludge and thereby form a sludge floc. The flock formation method may be a known method.

  Further, if necessary, an inorganic flocculant, an organic cationic compound, a cationic polymer flocculant and an anionic polymer flocculant can be used in combination.

  Examples of the inorganic flocculant include aluminum sulfate, polyaluminum chloride, ferric chloride, ferrous sulfate, and polyiron sulfate.

  Examples of organic cationic compounds include polymer polyamines, polyamidines, and cationic surfactants.

When an inorganic flocculant or an organic cationic compound is added, it is preferable to adjust the pH to 4 to 8 because the sludge can be treated more effectively.
As a method for adjusting the pH, after adding an inorganic flocculant or an organic cationic compound, when the pH value is satisfied, pH adjustment is not particularly required, but when the range limited by the present invention is not satisfied, an acid is used. Or it adjusts by adding an alkali.
Examples of the acid include hydrochloric acid, sulfuric acid, acetic acid and sulfamic acid. Examples of the alkali include caustic soda, caustic potash, slaked lime, and ammonia.

  Examples of the cationic polymer flocculant include a homopolymer of the aforementioned cationic monomer and a copolymer of the aforementioned cationic monomer and nonionic monomer.

  Examples of the anionic polymer flocculant include a homopolymer of the aforementioned anionic monomer and a copolymer of the aforementioned anionic monomer and nonionic monomer.

  The addition ratio of the polymer flocculant to the sludge is preferably 5 to 500 ppm as the solid content of the polymer flocculant, and preferably 0.05 to 1% by mass with respect to SS. When the polymer flocculant and other polymer flocculants are used in combination, it is preferable that the total amount of all the polymer flocculants satisfies the addition ratio.

  The added amount of sludge dewatering agent and other flocculant, the stirring speed, the stirring time, and the like may be in accordance with conventional dewatering conditions.

  The flocs thus formed are dehydrated using a known means to obtain a dehydrated cake.

  Examples of the dehydrator include a screw press dehydrator, a belt press dehydrator, a filter press dehydrator, and a screw decanter.

The sludge dewatering agent of the present invention can also be applied to a dewatering method using a granulation concentration tank having a filtration part.
Specifically, after adding an inorganic flocculant to the sludge and further adding a sludge dewatering agent, or together with the sludge dewatering agent, the sludge is introduced into a granulation concentration tank having a filtration part, and filtered from the filtration part. Examples include a method of taking out the liquid and granulating, and dehydrating the granulated product with a dehydrator.

3-2. Yield improver and papermaking method When the composition of the present invention is used as a yield improver, the polymer is preferably a powder or reverse phase emulsion. In actual use, as described above, when the polymer is a powder, the powder is dissolved in water and used as an aqueous solution. When the polymer is a reversed-phase emulsion, it is diluted with water and phase-inverted. And used as an oil-in-water emulsion. As solid content in this case, 0.01-0.5 mass% is preferable in any case, More preferably, it is 0.01-0.1 mass%.
As a method of using the yield improver, a conventional method may be used. For example, it is added when the stock is diluted to the final concentration to be fed into the paper machine, or after the dilution.

As the paper material to which the yield improver is applied, it may be any material used in a normal papermaking process, and usually contains at least pulp and filler, and if necessary, additives other than filler, specifically , Sizing agent, fixing agent, paper strength enhancer, colorant and the like.
The yield improver of the present invention can be preferably applied to a pulp having a relatively high ratio of used paper such as deinked used paper in the pulp. Further, the yield improver of the present invention can be preferably applied to a papermaking system, a neutral papermaking system and a high-speed papermaking system having a high filler ratio.
Examples of the filler include clay, kaolin, agarite, talc, calcium carbonate, magnesium carbonate, lime sulfate, barium sulfate, zinc oxide, and titanium oxide. Examples of the sizing agent include acrylic acid / styrene copolymer, examples of the fixing agent include sulfuric acid band, cationic starch, and alkyl ketene dimer, and examples of the paper strength enhancer include starch and cationic or amphoteric polymer. Examples include acrylamide.

A preferable addition ratio of the yield improver is preferably 0.05 to 0.8 mass%, more preferably 0.05 to 0.5 mass%, based on the dry pulp mass in the paper stock.
The pH of the paper stock after the addition of the yield improver is preferably maintained at 5 to 10, more preferably 5 to 8. Following the addition of the yield improver, the stock is immediately fed into the paper machine.

  The composition of the present invention is useful as a polymer flocculant because it is excellent in dewaterability such as filtration rate and moisture content and floc granulation, and is particularly useful as a sludge dewatering agent and a yield improver for papermaking. It is.

The composition of the present invention is a composition comprising the amphoteric polymer 1 and the amphoteric polymer 2.
As the amphoteric polymer to be used, those shown below are preferable.
That is, as the long-chain hydrophilic group in the amphoteric polymer, a polymer having an alkylene oxide group repeating number of 5 or more is preferable, and the amphoteric polymer is an ethylenic group having one terminal represented by the general formula (1). A polymer obtained by polymerizing a PRO oligomer having an unsaturated group, a cationic monomer, and an anionic monomer is preferred. In this case, the other end of the PRO oligomer preferably has an alkoxyl group having 1 to 8 carbon atoms.
Further, the composition of the present invention is useful as a polymer flocculant, and particularly useful as a sludge dehydrating agent.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
In the following, “part” means part by mass.

○ Production Example 1
Allyloxypoly (ethylene glycol / propylene glycol) monobutyl ether [Nippon Yushi Co., Ltd. trade name PKA-5015. Ethylene glycol / propylene glycol is a block copolymer with a molar ratio of 75:25. Number of ethylene oxide repeats = 24 on average, number of propylene oxide repeats = average 8 Number average molecular weight: 1600. Hereinafter referred to as “PKA-5015”), dimethylaminoethyl acrylate methyl chloride quaternary salt (hereinafter referred to as DAC) aqueous solution, acrylic acid (hereinafter referred to as AA) aqueous solution and acrylamide (hereinafter referred to as AM) aqueous solution. The monomer was PKA-5015 / DAC / AA / AM = 1/42/5/52 in molar ratio (PKA-5015 / DAC / AA / AM = 11.6 / 59.0 / 2.6 / in weight ratio). In 26.8), a total of 800 g was charged in a stainless steel reaction vessel so that the solid content was 38%.
Subsequently, after nitrogen gas is blown into the solution for 60 minutes, the solution temperature is adjusted to 10 ° C., and based on the solid weight of all monomers, 1000 ppm of azobisamidinopropane hydrochloride and 35 ppm of sodium bisulfite are obtained. In addition to the above, polymerization was carried out by irradiating from above the reaction vessel with a 100 W black light at an irradiation intensity of 6.0 mW / cm ² for 60 minutes to obtain a hydrogel-like amphoteric polymer.
The obtained amphoteric polymer was taken out of the container, dried and pulverized to obtain a powdery amphoteric polymer. This amphoteric polymer is referred to as PCR-1.
About the obtained amphoteric polymer, salt viscosity was measured. The results are shown in Table 1.

○ Production Examples 2-5
An amphoteric polymer was produced in the same manner as in Production Example 1 except that the components and ratios used were changed as shown in Table 1 below. In addition, about the manufacture examples 3-5, PKA-5015 was not used but only the monomer was used.
About the obtained amphoteric polymer, 0.5% salt viscosity was measured. The results are shown in Table 1.

* Example 1
50 parts of PCR-1 and 50 parts of PCR-2 were used as an amphoteric polymer, and these were mixed to produce a composition, which was used as a polymer flocculant (hereinafter referred to as PBL-1).
200 ml of paper sludge (SS: 13,000 mg / l, VSS: 10,000 mg / l, fiber content: 4500 mg / l) was collected in a 300 ml beaker, and 0.2% aqueous solution of polymer flocculant was 30 ppm with respect to the sludge. Then, the mixture was stirred with a jar tester at 150 rpm for 60 seconds to form a flock. The granulation property of the floc at this time was evaluated in the following three stages, and the particle size of the obtained floc was measured.
Thereafter, an 80-mesh filter cloth was laid on Nutsche, a cylinder was set up thereon, the sludge floc dispersion was poured into the cylinder, and gravity filtered. The filtrate volume after 10 seconds was measured and used as the filtration rate. The appearance of the obtained filtrate was visually observed and evaluated in the following three stages. After filtration, the cylinder was removed, and the obtained cake was evaluated in the following three stages. The evaluation results are shown in Table 3.

・ Excellent granulation: Flocs with large particle diameters were formed immediately after stirring, and the flocs were not easily destroyed by stirring.
Good: A floc with a large particle diameter was formed immediately after stirring, but the floc was easily broken by stirring.
Poor: Even if stirring was continued, only flocs with a relatively small particle size were formed, and even if formed, they were easily broken by stirring.

-Filter appearance excellent: completely transparent. Good: Slightly suspended matter. Bad: There are many suspended matters.

・ Self-standing excellent: The cake stood completely on its own. Good: The cake flowed slightly. Bad: The cake has flowed.

* Comparative example 1 and 2
Sludge was dehydrated in the same manner as in Example 1 except that the composition BL-1 shown in Table 2 below and CO-1 shown in Table 1 were used as the polymer flocculant.
Results evaluated in the same manner as in Example 1 are shown in Table 3.

The polymer flocculant of Example 1 was excellent in all the dewatering performances evaluated.
In contrast, the polymer flocculant BL-1 used in Comparative Example 1 corresponds to a polymer blend that does not copolymerize the hydrophilic monomer in PBL-1, but when stirring is continued. The flocs were easily broken, and as a result, various dewatering performances were insufficient. The polymer flocculant CO-1 used in Comparative Example 2 is a polymer that has the same monomer composition as PBL-1, but consists of a single amphoteric polymer and does not copolymerize a hydrophilic monomer. Also, this was inferior in floc granulation properties and various dewatering performances were insufficient.

The composition of the present invention can be preferably used as a polymer flocculant, more preferably as a sludge dehydrating agent and a yield improver, and particularly preferably as a sludge dehydrating agent.

Claims (6)

Two water-soluble amphoteric polymers having a cationic monomer unit, an anionic monomer unit, and a monomer unit having a long-chain hydrophilic group, and having the long-chain hydrophilic group in a graft form (Hereinafter referred to as amphoteric polymer 1 and amphoteric polymer 2), wherein the ratio of the cationic monomer unit and the anionic monomer unit in the amphoteric polymer is represented by the following formulas (1) to ( A composition satisfying 3).
Ca ₁ / An ₁ ≧ 1 (1)
Ca ₂ / An ₂ ≧ 1 (2)
| (Ca ₁ −An ₁ ) − (Ca ₂ −An ₂ ) | ≧ 1.5 (3)
[However, in the above formulas (1) to (3), Ca ₁ and An ₁ are all cationic units when the total amount of all constituent monomer units in the amphoteric polymer ₁ is converted to 100 mol, respectively. Represents the number of moles of the monomer unit and the total anionic monomer unit, and Ca ₂ and An ₂ are the same as described above for the total cationic monomer unit and the total anionic monomer in the amphoteric polymer 2, respectively. Represents the number of moles of units. ] The composition according to claim 1, wherein the amphoteric polymer is a polymer having a polyalkylene oxide group having 5 or more repeating alkylene oxide units as a long-chain hydrophilic group. The amphoteric polymer is a polymer obtained by polymerizing a polyalkylene oxide oligomer whose one end is an ethylenically unsaturated group represented by the following general formula (1), a cationic monomer and an anionic monomer: The composition according to claim 2, wherein
R ¹ CH═C (R ² ) −X− (1)
[In the above formula, R ¹ and R ² are hydrogen or an alkyl group having 1 to 3 carbon atoms, X is —R ³ O—, —O— or —R ⁴ NHCOO—, and R ³ and R ⁴ are An alkylene group having 1 to 4 carbon atoms, or -Ph- or -Ph-R ^5- , Ph is a phenylene group which may have a substituent, and R ⁵ is a carbon atom having 1 to 4 carbon atoms. An alkylene group; ] The said polyalkylene oxide oligomer has a C1-C8 alkoxyl group as another terminal, The composition of Claim 3 characterized by the above-mentioned. A polymer flocculant comprising the composition according to any one of claims 1 to 4. A method for dewatering sludge, comprising adding the polymer flocculant according to claim 5 to the sludge for dehydration.