JP2013155319A - Acrylic acid-based copolymer, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer having better handleability and putrescibility resistance than conventional polymers.SOLUTION: An acrylic acid-based polymer composition contains (i) an acrylic acid-based polymer essentially having a structural unit represented by general formula (1) and having a weight-average molecular weight of 2,000 to 50,000, and (ii) a propionic acid (salt) and acetic acid (salt), wherein the content of the total of the propionic acid (salt) and the acetic acid (salt) with respect to the acrylic acid-based polymer is ≥50 ppm and ≤0.5 mass%. In the formula (1), M is a hydrogen atom, a metal atom, an ammonium group or an organic amine group.

Description

The present invention relates to an acrylic acid copolymer and a method for producing the same.

Acrylic acid used as a raw material for water-soluble polymers and the like is widely used industrially by subjecting acrolein obtained by a gas phase oxidation reaction of propylene to a gas phase oxidation reaction.
In recent years, efforts have been made to produce acrylic acid using raw materials derived from plant raw materials from the viewpoint of depletion of petroleum resources and environmental considerations. For example, it is disclosed that acrylic acid is produced by subjecting a gas-phase dehydration reaction product of glycerin to gas-phase oxidation (Patent Document 1).

On the other hand, acrylic acid-based copolymers are water-soluble polymers and are widely used in various fields. Among them, those having a low molecular weight are excellent in chelating ability and dispersion performance, and are used for inorganic pigments and metals. Dispersants such as ions; detergent builders; water treatment agents such as anticorrosion agents and scale inhibitors; cement additives; and granulation treatment agents for iron-making raw materials. 3).
Here, although the water-soluble polymer is widely distributed in the form of an aqueous solution, for example, as a detergent builder or a pigment dispersant, when used for the production of a detergent composition or an inorganic particle slurry, the production process of the product to be obtained Therefore, a water-soluble polymer aqueous solution having a low water content is required. However, when the amount of water in the water-soluble polymer aqueous solution is lowered, the viscosity of the water-soluble polymer aqueous solution increases, which causes a problem in handling.

For example, when a water-soluble polymer aqueous solution is shipped in a drum can and sent to a raw material tank for use in a detergent manufacturing process or a pigment slurry manufacturing process at the time of use, the pump is damaged due to an excessive load on the pump. There are also problems such as clogging of piping.
Further, when the drum can is heated with a drum heater or the like to reduce the viscosity, it is difficult to locally control the temperature, which may cause coloration and may cause deterioration in quality of the detergent or paper product.

  In general, an acrylic acid polymer is a compound that hardly perishes. However, for example, when a water-soluble polymer aqueous solution is shipped in a drum can over a long period of time by ship, molds may occur rarely.

JP 2005-213225 A JP 11-128715 A JP 2000-80396 A

Provided are an acrylic acid polymer having better handling and higher stability during distribution and a method for producing the same.

As a result of intensive studies on various acrylic polymers (compositions) in order to achieve the above object, the present inventors have found that a specific acrylic polymer (composition) has good handling properties and The present invention has been completed by finding that it exhibits anti-septic (anti-mold) properties.
That is, the present invention includes (i) an acrylic acid polymer having a structural unit represented by the following general formula (1) as an essential component and having a weight average molecular weight of 2000 to 50000, and (ii) propionic acid (salt). And an acrylic acid polymer composition containing acetic acid (salt), wherein the total content of propionic acid (salt) and acetic acid (salt) is 50 ppm or more and 0.5 mass with respect to the acrylic acid polymer. % Is an acrylic acid-based polymer composition.

In the general formula (1), M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.
The present invention also includes (i) an acrylic acid polymer having a structural unit represented by the following general formula (1) as an essential component and having a weight average molecular weight of 2000 to 50000, (ii) propionic acid (salt), and An acrylic acid polymer composition containing acetic acid (salt), wherein the total content of propionic acid (salt) and acetic acid (salt) is 50 ppm or more and 0.5% by mass with respect to the acrylic acid polymer. The acrylic acid polymer is an acrylic acid polymer composition produced by polymerizing acrylic acid using glycerin as an essential component.

In the general formula (1), M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.

  In another aspect of the present invention, a method for producing a polymer is provided. That is, the method for producing a polymer of the present invention is a method for producing an acrylic acid-based polymer, characterized in that acrylic acid containing propionic acid (salt) and acetic acid (salt) is used as an essential component. A method for producing an acrylic acid-based copolymer, wherein the total content of propionic acid (salt) and acetic acid (salt) is polymerized in a range of 50 ppm to 0.5 mass% with respect to the acid. .

Since the polymer of the present invention exhibits excellent good handleability and rot resistance, it can be suitably used for water-soluble polymer applications such as detergent builders.

Hereinafter, the present invention will be described in detail.

[Acrylic acid polymer (also referred to as a polymer of the present invention)]
<Required structural unit>
The polymer of the present invention is characterized by having a structural unit represented by the following general formula (1) as an essential component.

なお、一般式（１）においてＭがアンモニウム基であるとは、−ＣＨ_２ＣＨ（ＣＯＯＮＨ_４）−で表される構造をいう。上記一般式においてＭは、本発明の重合体の製造が容易であり、また本発明の重合体を洗剤用途等に使用した場合の洗浄力の向上効果等に優れることから、水素原子、ナトリウム原子、カリウム原子であることが好ましく、ナトリウム原子であることが特に好ましい。
上記一般式（１）で表される構造単位は、アクリル酸（塩）を必須とする単量体成分を重合開始剤の存在下で重合することによって形成することが好ましい。ここで、アクリル酸（塩）とは、アクリル酸、アクリル酸塩をいう。アクリル酸塩における塩とは、金属塩、アンモニウム塩、有機アミン塩であり、金属塩としては、リチウム塩、ナトリウム塩、カリウム塩等のアルカリ金属塩、カルシウム塩、マグネシウム塩等のアルカリ土類金属塩が例示される。有機アミン塩としては、メチルアミン塩、エチルアミン塩、ジエチルアミン塩、トリエチルアミン塩等のアルキルアミン塩；モノエタノールアミン塩、ジエタノールアミン塩等のアルカノールアミン塩；ジエチレンアミン塩、ジエチレントリアミン塩等のポリアミン塩等が例示される。塩の中でもナトリウム塩、カリウム塩が特に好ましい。
なお、上記一般式（１）で表される構造単位をアクリル酸（塩）由来の構造単位と言うことがあるが、アクリル酸（塩）由来の構造単位を含むとは最終的に得られた重合体が上記一般式（１）で表される構造単位を含むことを意味し、アクリル酸（塩）を重合させることによって重合体中に導入されたものに限られない。

In the general formula (1), M being an ammonium group refers to a structure represented by —CH ₂ CH (COONH ₄ ) —. In the above general formula, M is easy to produce the polymer of the present invention, and is excellent in the effect of improving the detergency when the polymer of the present invention is used for detergents and the like. A potassium atom is preferred, and a sodium atom is particularly preferred.
The structural unit represented by the general formula (1) is preferably formed by polymerizing a monomer component essentially containing acrylic acid (salt) in the presence of a polymerization initiator. Here, acrylic acid (salt) refers to acrylic acid and acrylate. The salt in the acrylate is a metal salt, ammonium salt, organic amine salt, and the metal salt is an alkali metal salt such as lithium salt, sodium salt or potassium salt, or an alkaline earth metal such as calcium salt or magnesium salt. Salts are exemplified. Examples of organic amine salts include alkylamine salts such as methylamine salts, ethylamine salts, diethylamine salts, and triethylamine salts; alkanolamine salts such as monoethanolamine salts and diethanolamine salts; polyamine salts such as diethyleneamine salts and diethylenetriamine salts. Is done. Of the salts, sodium salt and potassium salt are particularly preferable.
In addition, although the structural unit represented by the general formula (1) is sometimes referred to as a structural unit derived from acrylic acid (salt), the structural unit derived from acrylic acid (salt) was finally obtained. It means that the polymer contains the structural unit represented by the general formula (1), and is not limited to those introduced into the polymer by polymerizing acrylic acid (salt).

In the polymer of the present invention, the structural unit represented by the general formula (1) is a structural unit derived from all monomers (the structure represented by the general formula (1)) unless otherwise specified depending on the application. It is preferable to have a ratio of 5 mass% to 100 mass% with respect to 100 mass%). When the structural unit represented by the general formula (1) is within the above range, the dispersibility of the polymer is excellent. From the viewpoint of improving the detergency and chelating power of the polymer, the structural unit represented by the general formula (1) is 50% by mass or more and 100% by mass with respect to 100% by mass of the structural unit derived from all monomers. Or less, more preferably 80% by mass or more and 100% by mass or less, and particularly preferably 90% by mass or more and 100% by mass or less.
In this invention, when calculating the ratio with respect to the structural unit derived from all the monomers of the structural unit represented by the said General formula (1), it shall calculate in conversion of a corresponding acid type. For example, when the structural unit represented by the general formula (1) is a salt type structure represented by —CH ₂ —CH (COONa) —, —CH ₂ —CH ( Calculate mass percentage as COOH)-.

<Structural units derived from other monomers>
The polymer of the present invention essentially comprises the structural unit represented by the general formula (1), but may contain a structural unit (e) derived from another monomer.

The structural unit (e) derived from another monomer is a structure in which the unsaturated double bond of the other monomer is a single bond. For example, when the monomer (E) is methyl acrylate, The structural unit (e) derived from another monomer can be represented by —CH ₂ —CH (COOCH ₃ ) —. Including the other monomer-derived structural unit (e) means that the finally obtained polymer contains the other monomer-derived structural unit (e). It is not restricted to what was introduce | transduced in the polymer by polymerizing a monomer (it is also mentioned a monomer (E)).

The other monomer is preferably a monomer copolymerizable with acrylic acid (salt).
The other monomer (E) is not particularly limited and is appropriately selected depending on the desired effect.
Specifically, unsaturated monocarboxylic acids other than the acrylic acid (salt) such as methacrylic acid, crotonic acid, α-hydroxyacrylic acid, α-hydroxymethylacrylic acid and derivatives thereof, and salts thereof; itaconic acid , Fumaric acid, maleic acid, unsaturated dicarboxylic acids such as 2-methyleneglutaric acid and their salts; vinylsulfonic acid, 1-acrylamide-1-propanesulfonic acid, 2-acrylamido-2-propanesulfonic acid, 2- ( (Meth) acrylamide-2-methyl-1-propanesulfonic acid, (meth) allyloxybenzenesulfonic acid, styrenesulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, (meth) allylsulfonic acid, isoprenesulfonic acid 3-allyloxy-2-hydroxypropanesulfonic acid , And sulfonic acid group-containing monomers such as salts thereof; (meth) allyl alcohol, monomers having a structure obtained by adding alkylene oxide to isoprenol, polyalkylene glycols such as (meth) acrylic acid esters of alkoxyalkylene glycols Chain-containing monomers: N-vinyl monomers such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylformamide, N-vinyl-N-methylacetamide, N-vinyloxazolidone Amide monomers such as (meth) acrylamide, N, N-dimethylacrylamide and N-isopropylacrylamide; allyl ether monomers such as (meth) allyl alcohol; isoprene monomers such as isoprenol; Butyl (meth) acrylate, 2-ethylhex (Meth) acrylic acid alkyl ester monomers such as ru (meth) acrylate and dodecyl (meth) acrylate; hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (Meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, α-hydroxymethylethyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyneopentyl (meth) acrylate, hydroxyhexyl (Meth) acrylate hydroxyalkyl monomers such as (meth) acrylate; vinyl aryl monomers such as styrene, indene and vinylaniline, isobutylene, vinyl acetate; vinylpyridine, vinyl Vinyl aromatic amino group-containing monomers having a heterocyclic aromatic hydrocarbon group and an amino group, such as nilimidazole, and quaternized products and salts thereof; dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl acrylate Aminoalkyl (meth) acrylates such as aminoethyl methacrylate and quaternized products and salts thereof; allylamines such as diallylamine and diallyldimethylamine and quaternized products and salts thereof; (i) (meth) allyl glycidyl ether; (Ii) Dialkylamines such as dimethylamine, diethylamine, diisopropylamine, di-n-butylamine, diethanolamine, diisopropanolamine, etc. on the epoxy ring of isoprenyl glycidyl ether and vinyl glycidyl ether Alkanolamine, iminodiacetic acid, amino acids such as glycine, morpholine, quaternary compound or salt amine of monomers and obtained by reacting such cyclic amines pyrrole etc., etc., can be mentioned.
Moreover, the said other monomer (E) may be used individually by 1 type, or may be used with the form of a 2 or more types of mixture.

The polymer of the present invention is optional, but the structural unit (e) derived from another monomer is 0% by mass to 95% by mass with respect to 100% by mass of the structure derived from all monomers. Are preferred (except where otherwise mentioned depending on the application). The proportion of the structural unit (e) with respect to 100 mol% of the structure derived from all monomers is more preferably 0% by mass or more and 50% by mass or less, further preferably 0% by mass or more and 20% by mass or less, and particularly preferably. Is 0 mass% or more and 10 mass% or less.
In the present invention, when calculating the ratio of the structural unit derived from the other monomer to the structural unit derived from all the monomers (e), the case where the other monomer has an acid group salt corresponds. It is calculated in terms of acid type. If it has an amino group salt, it should be calculated in terms of the corresponding unneutralized amine. If it has a quaternized amino group, the mass of the counter anion is not included. It shall be calculated in

<Other structural units>
The polymer of the present invention may contain a structural unit derived from an initiator or a chain transfer agent. For example, a sulfonic acid (salt) group derived from bisulfite, a hydroxyl group derived from hydrogen peroxide, a phosphinate group derived from hypophosphorous acid (salt), and the like are preferably exemplified. In particular, it is preferable that the polymer of the present invention has a sulfonic acid (salt) group because the salt resistance of the polymer is improved.
The structural unit derived from the initiator and the chain transfer agent is more preferably 0.05 to 10% by mass, and 0.1 to 5% by mass with respect to 100% by mass of the structure derived from all monomers. More preferably.

<Molecular weight of acrylic acid polymer>
The weight average molecular weight Mw of the acrylic acid polymer according to the present invention is 2000 to 50000, preferably 2500 to 25000, and more preferably 3000 to 15000. When the weight average molecular weight is within this range, the (meth) acrylic acid polymer can exhibit various performances such as dispersibility, chelating ability and gel resistance more remarkably and effectively. Therefore, it can be used more suitably for applications such as dispersants, scale inhibitors, and detergent builders. When the weight average molecular weight of the acrylic acid polymer is less than 2,000, sufficient chelating ability and calcium carbonate scale prevention ability tend to be lowered. On the other hand, when the weight average molecular weight of the acrylic polymer exceeds 50,000, gel resistance and dispersibility tend to be lowered.

  Moreover, the dispersity (Mw / Mn) of the acrylic acid polymer according to the present invention is 1.5 to 10, preferably 1.5 to 5.0, more preferably 1.5 to 2.7. If it is the said range, the improvement effect of dispersibility etc. will become easy to be acquired.

  In addition, the said weight average molecular weight (Mw) and number average molecular weight (Mn) are measured by the method described in the below-mentioned Example.

<S atom contained in acrylic acid polymer>
The acrylic acid polymer of the present invention preferably contains a sulfur atom in the molecule. More preferably, a sulfonic acid group is included at the end of the main chain of the molecule. Having a sulfonic acid group at the end of the main chain is preferable because gel resistance is remarkably improved without adversely affecting the performance of calcium carbonate such as scale prevention ability and calcium chelate ability.
For example, when bisulfite is used as a chain transfer agent, a part is incorporated into the molecular structure of the polymer. In this case, it is usually introduced as a sulfonic acid group at the end of the main chain of the molecule. Here, it is preferable to carry out polymerization by the method for producing an acrylic acid polymer of the present invention described later, because it is possible to suppress the generation of impurities and efficiently introduce sulfonic acid groups to the ends of the main chain.

By the way, the acrylic acid polymer (composition) usually contains a raw material residue and the like in addition to the acrylic acid copolymer. For example, when bisulfite is used for the chain transfer agent, impurities containing S atoms are included. If these impurities increase, the physical properties of the acrylic acid polymer will decrease, and if the polymer is stored in the form of an aqueous solution, the precipitation of impurities during low-temperature storage may become a problem. It is preferable to reduce the amount of impurities as much as possible. Specifically, when the acrylic acid polymer of the present invention contains S atoms, the content of S atoms contained in the acrylic acid polymer (composition) is determined by an ICP method using a dialysis membrane described later. Measured,
It is preferable to set the sulfur element introduction amount S value defined by S value = (S amount contained in polymer) / (total S amount) × 100 to 35 or more. For polymers having a sulfur element introduction amount S value of 35 or more, it is possible to suppress the performance degradation due to the impurities to a very low level, and to suppress the precipitation of impurities during low-temperature storage in the form of an aqueous solution. Can do. Here, the sulfur element introduction amount S value of the acrylic polymer is preferably 35 or more, more preferably 35 to 70, and still more preferably 40 to 60.

The “S amount contained in the polymer” used for the definition of the sulfur element introduction amount S value refers to the S amount contained in the acrylic acid polymer. Specifically, after removing low molecular weight components such as impurities and initiator fragments from an aqueous solution prepared by adjusting the solid content concentration of an acrylic acid polymer obtained by polymerization, which is measured by a dialysis method described in Examples. The amount of S contained in the polymer component consisting of the acrylic acid polymer. In other words, it can be said that the amount of sulfur introduced as a sulfur-containing group such as a sulfonic acid group at the terminal or side chain of the acrylic acid polymer. Therefore, the larger the sulfur element introduction amount S value, the more the initiator used, etc. It can be said that more of the S component contained in the polymer is suitably introduced into the polymer by the polymerization reaction, and the “total S amount” used in the definition of the sulfur element introduction amount S value is an acrylic acid heavy polymer. This refers to the total amount of S contained in the composition in which the coalescence is present, where the amount of S in the raw material used for the polymerization was not used as the total amount of S because it was discharged out of the system as sulfurous acid gas. This is because the amount of sulfur (sulfur content) is not present in the acrylic acid polymer (aqueous solution), so that there is no risk of precipitation as an S-containing impurity during low-temperature storage.
As described above, when polymerization is carried out by the method for producing an acrylic acid polymer of the present invention, which will be described later, it becomes possible to suppress the generation of impurities and efficiently introduce sulfonic acid groups to the ends of the main chain.

<Acrylic acid polymer composition>
The acrylic acid polymer composition of the present invention contains (i) the acrylic acid polymer of the present invention and (ii) propionic acid (salt) and acetic acid (salt) as essential components. 1 or more chosen from an initiator residue, a residual monomer, the by-product at the time of superposition | polymerization, and a water | moisture content is contained. The acrylic acid polymer composition of the present invention has a total content of propionic acid (salt) and acetic acid (salt) of 50 ppm or more and 0.005% relative to the acrylic acid polymer of the present invention (acid type conversion). It is characterized by being 5% by mass or less. Within the above range, the effect of reducing the viscosity when the acrylic polymer composition of the present invention is an aqueous solution is exhibited, and the cleaning power when the acrylic polymer composition is used for detergent is also present. It can be maintained. Furthermore, generation | occurrence | production of mold | fungi in an acrylic acid type polymer composition can be suppressed effectively. The total content of propionic acid (salt) and acetic acid (salt) is preferably 60 ppm or more and 0.3% by mass or less with respect to the acrylic acid polymer of the present invention (in terms of acid type). The total content of salt) and acetic acid (salt) is more preferably 80 ppm or more and 0.25% by mass or less.
In addition, when calculating the mass ratio of the total content of the acrylic acid polymer, propionic acid (salt) and acetic acid (salt) in the acrylic acid polymer composition of the present invention, it is calculated in terms of acid type. . For example, in the case of sodium propionate, it is calculated as propionic acid, which is the corresponding acid.
Examples of the salt in propionic acid (salt) and acetic acid (salt) are metal salts, ammonium salts, and organic amine salts, and the same salts as those in acrylic acid (salt) are exemplified, but preferably sodium salt, Potassium salt.
The total content of propionic acid (salt) and acetic acid (salt) is as described above, but propionic acid (salt) is 0 because the antifungal effect of the polymer composition tends to be further improved. 0.5 ppm or more is preferable, and 1 ppm or more is preferable.
The copolymer of the present invention is preferably contained in an amount of 1 to 99.99% by mass with respect to 100% by mass of the polymer composition of the present invention (also referred to as an acrylic acid polymer aqueous solution of the present invention). One of the forms of a preferable copolymer composition is a form which contains 40-60 mass% of copolymers, and contains 40-60 mass% of water. If it is the said range, it will become possible to manufacture a product efficiently also in the manufacturing process of a detergent composition or a dispersing agent slurry.

<Method for producing acrylic acid polymer>
(Monomer composition)
The polymer production method of the present invention is 5% with respect to 100% by mass of the total amount of monomers used (total of acrylic acid (salt) and other monomers), unless otherwise specified depending on the application. More than 100% by mass of acrylic acid (salt) (also referred to as monomer (A)) is essential, and 0% by mass to 95% by mass with respect to 100% by mass of all monomers used as required. It is preferable to polymerize the following other monomers (monomer (E)) as optional components. In the method for producing a polymer of the present invention, the monomer (A) and the monomer (E) may be used alone or in combination of two or more.
The use amount of acrylic acid (salt) is more preferably 50% by mass or more and 100% by mass or less, and more preferably 80% by mass or more and 100% by mass or less with respect to 100% by mass of the total monomer use amount. More preferably, it is 90 mass% or more and 100 mass% or less.
The amount of the other monomer used as an optional component is more preferably 0% by mass or more and 50% by mass or less, and 0% by mass or more and 20% by mass with respect to 100% by mass of the total monomer usage. % Or less, more preferably 0% by mass or more and 10% by mass or less.

In addition, it is preferable that acrylic acid used by this invention contains acrylic acid which uses glycerol as a raw material. As a by-product in the production method of acrylic acid using glycerin as a raw material, for example, as described in International Publication No. 2010/074177, as well as the advantage of reducing dependence on petroleum resources and less addition to the environment, Acetic acid and propionic acid are produced very much, and there arises a problem that it is difficult to remove acetic acid and propionic acid, but according to the method for producing a polymer of the present invention, without passing through an excessive purification step of acrylic acid, It becomes possible to use acrylic acid which preferably uses glycerin as a raw material. Further, there is an advantage that the effect of the present invention can be obtained due to acetic acid and propionic acid contained in acrylic acid using glycerin as a raw material.
In the production method of the present invention, when acrylic acid using glycerin as a raw material is used, the amount of acrylic acid used as a raw material (mass%) relative to the amount of total acrylic acid (salt) used is acrylic acid (salt) ) And propionic acid (salt) and acetic acid (salt), the total ratio (mass%) is preferably set in the following range. For example, it is preferable that the usage-amount of acrylic acid which uses glycerol as a raw material is 5-100 mass% with respect to the usage-amount of 100% of total acrylic acid (salt).
In the method for producing a polymer of the present invention, the total of propionic acid (salt) and acetic acid (salt) (acid type conversion) is 50 ppm or more and 0.5% by mass or less with respect to acrylic acid (salt) (acid type conversion). The aspect which superposes | polymerizes so that it may become the range of this is a preferable aspect. The propionic acid (salt) (acid type conversion) is more preferably 60 ppm or more and 0.3% by mass or less, and further preferably 80 ppm or more and 0.25% by mass or less.
However, with respect to acrylic acid (salt), polymerization is performed in a manner in which propionic acid (salt) and acetic acid (salt) are not present, and by adding a predetermined amount of propionic acid (salt) and acetic acid (salt) after polymerization, You may manufacture the polymer composition of this invention.

(Initiator)
In the method for producing a polymer of the present invention, the above monomer components (monomer (A) and monomer (E) are sometimes referred to as monomer compositions) are present in the presence of a polymerization initiator. It is preferable to polymerize with.
As the initiator, known ones can be used, for example, hydrogen peroxide; persulfates such as sodium persulfate, potassium persulfate, ammonium persulfate; dimethyl 2,2′-azobis (2-methylpro Pionate), 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2, 2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyric acid) dimethyl, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-Methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] n hydrate, 2,2′-azobis [2- (2- Imidazoline- 2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 1,1′-azobis (cyclohexane-1-carbohydrate) Suitable are azo compounds such as nitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide, and the like. Among these polymerization initiators, since the gel resistance and salt resistance of the resulting polymer tend to be improved, it is preferable to use a persulfate as described later.
The amount of the initiator used is not particularly limited as long as it is an amount capable of initiating polymerization of the monomer (A) and, if necessary, another monomer (E). The amount is preferably 15 g or less, more preferably 1 to 12 g, based on 1 mol of all monomer components composed of the monomers (A) and (E).

(Chain transfer agent)
In the method for producing a polymer of the present invention, a chain transfer agent may be used as a molecular weight adjusting agent of the polymer as long as it does not adversely affect the polymerization. Specific examples of the chain transfer agent include mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropion, 3-mercaptopropion, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, 2- Thiol chain transfer agents such as mercaptoethanesulfonic acid, n-dodecyl mercaptan, octyl mercaptan, butylthioglycolate; halides such as carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane; Secondary alcohol; phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, bisulfite, dithionite, metabisulfite, and salts thereof ( Sodium bisulfite, potassium bisulfite, sub Sodium dithionite, potassium dithionite, sodium metabisulfite, metabisulfite potassium, etc.) and the like, and the like lower oxides and salts thereof. The chain transfer agent may be used alone or in the form of a mixture of two or more.
When a chain transfer agent is used, there is an advantage that a polymer to be produced can be prevented from having a higher molecular weight than necessary, and a low molecular weight copolymer can be produced efficiently. Among these, in the polymerization reaction according to the present invention, it is preferable to use bisulfite as described above. Thereby, it becomes possible to introduce a sulfonic acid group quantitatively to the end of the main chain of the obtained polymer, and it becomes possible to improve salt resistance and gel resistance. Further, it is preferable to use bisulfite as the chain transfer agent because the color tone of the polymer (composition) can be improved.
In the production method of the present invention, the addition amount of the chain transfer agent is not limited as long as the monomer (A) and, if necessary, the other monomer (E) is polymerized satisfactorily, Except where indicated, preferably 1 to 20 g, more preferably 2 to 15 g, based on 1 mol of all monomer components consisting of monomer (A) and other monomer (E) if necessary. It is.

(Preferable combination of initiator and chain transfer agent (also called initiator system))
In the method for producing a polymer of the present invention, it is preferable to use a combination of one or more persulfates and bisulfites as an initiator system. Thereby, a sulfonic acid group can be quantitatively introduced into the terminal or side chain, and a low molecular weight water-soluble polymer that is particularly excellent in salt resistance and gel resistance in addition to dispersibility and chelating ability can be obtained. The effects of the present invention can be effectively expressed. By adding bisulfite to the initiator system in addition to persulfate, it is possible to inhibit the resulting polymer from becoming higher in molecular weight than necessary, and to efficiently produce a low molecular weight polymer.

Specific examples of the persulfate include sodium persulfate, potassium persulfate, and ammonium persulfate.
In the present invention, bisulfite includes bisulfite and pyrosulfite, and specific examples include sodium bisulfite, potassium bisulfite, and ammonium bisulfite.
The addition ratio of the above-mentioned persulfate and bisulfite is 0.5 to 5 parts by mass, preferably 1 to 4 parts by mass, more preferably 2 to 3 parts by mass with respect to 1 part by mass of persulfate. Within the range of the part. When the amount of bisulfite is less than 0.5 parts by mass with respect to 1 part by mass of persulfate, the effect of bisulfite tends to be reduced. Therefore, the introduction amount of the sulfonic acid group at the terminal of the polymer is lowered, and the gel resistance of the polymer tends to be lowered. Further, the weight average molecular weight of the acrylic acid polymer also tends to increase. On the other hand, when bisulfite exceeds 5 parts by mass with respect to 1 part by mass of persulfate, excessive bisulfite is supplied in the polymerization reaction system in a state where the effect of bisulfite is not obtained as much as the addition ratio. Tend to be used (wasted). For this reason, excess bisulfite is decomposed in the polymerization reaction system, and a large amount of sulfurous acid gas is generated. In addition, a large amount of impurities in the acrylic acid polymer is generated, and the performance of the resulting acrylic polymer tends to deteriorate. In addition, impurities tend to precipitate during holding at a low temperature.

  The persulfate and bisulfite are added in an amount of 2 to 20 g, preferably 4 to 18 g, more preferably 6 to 15 g, based on 1 mol of the monomer. More preferably, it is 9-12g. When the added amount of the persulfate and bisulfite is less than 2 g, the molecular weight of the resulting polymer tends to increase. In addition, sulfur-containing groups such as sulfonic acid groups introduced at the ends of the resulting acrylic acid polymer tend to decrease. On the other hand, when the addition amount exceeds 20 g, the effects of persulfate and bisulfite cannot be obtained as the addition amount increases, and conversely, the purity of the resulting acrylic acid polymer tends to decrease.

  The persulfate, which is a kind of initiator, may be added in the form of a persulfate solution (preferably an aqueous solution) after being dissolved in a solvent described later, preferably water. The concentration when used as the persulfate solution (preferably an aqueous solution) is 1 to 35% by mass, preferably 5 to 35% by mass, and more preferably 10 to 30% by mass. Here, when the concentration of the persulfate solution is less than 1% by mass, the concentration of the product decreases, and transportation and storage become complicated. On the other hand, when the concentration of the persulfate solution exceeds 35% by mass, handling becomes difficult.

  Bisulfite, which is one type of chain transfer agent, may be added in the form of a bisulfite solution (preferably an aqueous solution) after being dissolved in a solvent described later, preferably water. The concentration when used as the bisulfite solution (preferably an aqueous solution) is 10 to 40% by mass, preferably 20 to 40% by mass, and more preferably 30 to 40% by mass. Here, when the concentration of the bisulfite solution is less than 10% by mass, the concentration of the product is lowered, and transportation and storage become complicated. On the other hand, when the concentration of the bisulfite solution exceeds 40% by mass, handling becomes difficult.

(Other additives)
In the method for producing a polymer of the present invention, as an additive other than an initiator and a chain transfer agent that can be used in a polymerization reaction system when the monomer is polymerized in an aqueous solution, the effect of the present invention Appropriate additives can be added in an amount that does not affect the above. For example, heavy metal concentration adjusting agents, pH adjusting agents and the like are used.
The heavy metal concentration adjusting agent is not particularly limited, and a polyvalent metal compound or a simple substance can be used. Specifically, vanadium oxytrichloride, vanadium trichloride, vanadyl oxalate, vanadyl sulfate, vanadic anhydride, ammonium metavanadate, ammonium sulfate hypovanadas [(NH4) 2SO4 · VSO4 · 6H2O], ammonium sulfate vanadas [(NH4 ) V (SO4) 2 · 12H2O], copper (II) acetate, copper (II), copper (II) bromide, copper (II) acetyl acetate, cupric ammonium chloride, ammonium copper chloride, copper carbonate, copper chloride (II), copper citrate (II), copper formate (II), copper hydroxide (II), copper nitrate, copper naphthenate, copper oleate (II), copper maleate, copper phosphate, copper sulfate (II ), Cuprous chloride, copper (I) cyanide, copper iodide, copper (I) oxide, copper thiocyanate, iron acetyl acetonate, iron ammonium citrate, Ferric ammonium oxalate, ammonium iron sulfate, ammonium ferric sulfate, iron citrate, iron fumarate, iron maleate, ferrous lactate, ferric nitrate, iron pentacarbonyl, ferric phosphate, Water-soluble polyvalent metal salts such as ferric pyrophosphate; polyvalent metal oxides such as vanadium pentoxide, copper (II) oxide, ferrous oxide, ferric oxide; iron (III) sulfide, iron sulfide ( II), polyvalent metal sulfides such as copper sulfide; copper powder and iron powder.
In the polymer production method of the present invention, it is desirable that the heavy metal ion concentration of the resulting acrylic acid polymer is 0.05 to 10 ppm. Therefore, an appropriate amount of the above heavy metal concentration regulator is added as necessary. Is desirable.

(Polymerization solvent)
In the method for producing a polymer of the present invention, the above monomers are usually polymerized in a solvent. In this case, the solvent used in the polymerization reaction system is water, alcohol, glycol, glycerin, polyethylene glycols. An aqueous solvent such as the above is preferable, and water is particularly preferable. These may be used alone or in combination of two or more. Moreover, in order to improve the solubility of the monomer in the solvent, an organic solvent may be appropriately added as long as it does not adversely affect the polymerization of each monomer.
Specifically, the organic solvent is selected from one or more types selected from lower alcohols such as methanol and ethanol; amides such as dimethylformaldehyde; ethers such as diethyl ether and dioxane; sell.
The amount of the solvent used is in the range of 40 to 200 mass%, preferably 45 to 180 mass%, more preferably 50 to 150 mass%, based on the total amount of monomers. When the amount of the solvent used is less than 10% by mass, the molecular weight becomes high. On the other hand, when the usage-amount of this solvent exceeds 200 mass%, the density | concentration of the manufactured acrylic acid type polymer will become low, and solvent removal will be needed depending on the case. It should be noted that most or all of the solvent may be charged into the reaction vessel at the initial stage of polymerization. For example, a part of the solvent may be added (dropped) appropriately into the reaction system alone during the polymerization. The monomer component, the initiator component, and other additives may be appropriately added (dropped) into the reaction system during the polymerization together with these components in the form of being previously dissolved in a solvent.

(Polymerization temperature)
The polymerization temperature in the polymerization of the monomer is usually 25 to 150 ° C, but preferably 25 to 99 ° C. The polymerization temperature is more preferably 50 ° C. or higher, and particularly preferably 70 ° C. or higher. The polymerization temperature is preferably 95 ° C or lower, more preferably 90 ° C or lower. When the polymerization temperature is lower than 25 ° C., the molecular weight increases and impurities increase. In addition, since the polymerization time takes too long, productivity is lowered. On the other hand, when the polymerization temperature exceeds 99 ° C., when bisulfite is used as the initiator system, the bisulfite is decomposed and a large amount of sulfurous acid gas is generated. For this reason, sulfurous acid gas dissolves in the liquid phase after polymerization, and impurities are formed. Further, during the polymerization, sulfurous acid gas is discharged out of the system, and recovery processing costs are required. In addition, since the bisulfite as an initiator escapes as sulfurous acid gas, a sufficient effect corresponding to the addition cannot be obtained, and the molecular weight cannot be lowered. The polymerization temperature here refers to the temperature of the reaction solution in the reaction system.

  In particular, in the case of the method of starting polymerization from room temperature (room temperature starting method), for example, when polymerization is performed in 180 minutes per batch (180 minute formulation), within 70 minutes, preferably 0 to 50 It is made to reach the set temperature (within the range of the polymerization temperature defined above, preferably 70 to 90 ° C., more preferably about 80 to 90 ° C.) in minutes, more preferably 0 to 30 minutes. Thereafter, it is desirable to maintain the set temperature until the polymerization is completed. When the temperature rise time is out of the above range, the resulting acrylic acid polymer may have a high molecular weight. In addition, although the example of the polymerization time is shown as 180 minutes, if the prescription of the polymerization time is different, referring to the example, the temperature increase time is set so that the ratio of the temperature increase time to the polymerization time is the same. Is desirable.

(Reaction system pressure, reaction atmosphere)
When polymerizing the monomer, the pressure in the reaction system is not particularly limited. The pressure may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure. Preferably, when bisulfite is used as the initiator system, the polymerization is carried out under normal pressure or under pressure in order to prevent the release of sulfurous acid gas during polymerization and to reduce the molecular weight. It is good. In addition, when polymerization is performed under normal pressure (atmospheric pressure), it is not necessary to provide a pressurizing device or a decompressing device, and it is not necessary to use a pressure-resistant reaction vessel or pipe. For this reason, normal pressure (atmospheric pressure) is preferable from the viewpoint of production cost. That is, optimal pressure conditions may be set as appropriate depending on the intended use of the resulting acrylic acid polymer.
The atmosphere in the reaction system may be maintained in an air atmosphere, but an inert atmosphere is preferable. For example, it is desirable to replace the inside of the system with an inert gas such as nitrogen before the start of polymerization. Thereby, atmospheric gas (for example, oxygen gas etc.) in the reaction system dissolves in the liquid phase and acts as a polymerization inhibitor. As a result, the initiator (persulfate, etc.) is prevented from being deactivated and reduced, and the molecular weight can be further reduced.

(Neutralization degree during polymerization)
In the production method of the present invention, the polymerization reaction of the monomer is preferably performed under acidic conditions. By carrying out the reaction under acidic conditions, an increase in the viscosity of the aqueous solution of the polymerization reaction system can be suppressed, and a low molecular weight acrylic acid polymer can be produced favorably. In addition, since the polymerization reaction can proceed under a higher concentration condition than before, the production efficiency can be significantly increased. In particular, by reducing the degree of neutralization during polymerization to 1 to 25 mol%, the effect of reducing the initiator amount can be synergistically increased, and the effect of reducing impurities can be significantly improved. Furthermore, it is desirable to adjust the reaction solution during polymerization so that the pH at 25 ° C. is 1-6. By carrying out the polymerization reaction under such acidic conditions, the polymerization can be carried out at a high concentration and in one stage. Therefore, it is possible to omit the concentration step which was necessary in some cases in the conventional manufacturing method. Therefore, the productivity of the acrylic acid polymer is greatly improved, and an increase in manufacturing cost can be suppressed.

  Among the above acidic conditions, the pH at 25 ° C. of the reaction solution during polymerization is preferably 1 to 6, more preferably 1 to 5, and still more preferably 1 to 4. When the pH is less than 1, the generation of sulfurous acid gas and the corrosion of the apparatus may occur. On the other hand, when the pH exceeds 6, when bisulfite is used as the initiator system, the efficiency of bisulfite decreases and the molecular weight increases.

  Examples of the pH adjuster for adjusting the pH of the reaction solution during the polymerization include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkaline earth metal waters such as calcium hydroxide and magnesium hydroxide. Examples thereof include oxides, organic amine salts such as ammonia, monoethanolamine, and triethanolamine. These may be used alone or in combination of two or more. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferable, and sodium hydroxide is particularly preferable. In the present invention, these may be simply referred to as “pH adjusting agent” or “neutralizing agent”.

  The degree of neutralization during the polymerization is preferably from 1 to 25 mol%, more preferably from 2 to 15 mol%, still more preferably from 3 to 10 mol%. If the degree of neutralization during polymerization is within such a range, it is possible to perform polymerization most favorably, and it is possible to reduce impurities and produce a polymer having good salt resistance and gel resistance. Moreover, the viscosity of the aqueous solution of the polymerization reaction system does not increase, and a low molecular weight polymer can be produced satisfactorily. In addition, since the polymerization reaction can proceed under a higher concentration condition than before, the production efficiency can be significantly increased. When the degree of neutralization during polymerization is less than 1 mol%, when bisulfite is used as the initiator system, the amount of sulfurous acid gas generated increases and the molecular weight may increase. On the other hand, when the degree of neutralization during polymerization exceeds 25 mol%, the chain transfer efficiency of bisulfite may decrease and the molecular weight may increase. In addition, as the polymerization proceeds, the viscosity of the aqueous solution in the polymerization reaction system increases significantly. As a result, the molecular weight of the resulting polymer increases more than necessary, and a low molecular weight polymer cannot be obtained. Furthermore, the effect of reducing the degree of neutralization cannot be fully exhibited, and it may be difficult to significantly reduce impurities.

  The neutralization method here is not particularly limited. For example, sodium acrylate or the like (a salt of acrylic acid may be used as a part of the raw material or neutralized during polymerization using an alkali metal hydroxide such as sodium hydroxide as a neutralizing agent. The neutralizing agent may be added in the form of a solid or an aqueous solution dissolved in a suitable solvent, preferably water. When the aqueous solution is used, the concentration of the aqueous solution is 10 to 60% by mass, preferably 20 to 55% by mass, and more preferably 30 to 50% by mass. However, when the concentration exceeds 60% by mass, there is a risk of precipitation, and the viscosity increases, so that the liquid feeding becomes complicated.

(Raw material addition conditions)
In the polymerization, the monomer, initiator, chain transfer agent and other additives are previously dissolved in a suitable solvent (preferably the same solvent as the solvent for the liquid to be dropped), As an initiator solution, a chain transfer agent solution, and other additive solutions, with respect to the (aqueous) solvent charged in the reaction vessel (adjusted to a predetermined temperature if necessary) at a predetermined dropping time. It is preferable to polymerize while dropping continuously. Further, a part of the aqueous solvent may be added dropwise later, separately from the initially charged solvent prepared in advance in a container in the reaction system. However, the production method of the present invention is not limited to these. For example, regarding the dropping method, it may be dropped continuously or may be dropped in several portions intermittently. One or two or more of the monomers may be initially charged in part or in whole (that is, it can be considered that all or part of the monomer is added dropwise at the start of polymerization). Also, the dropping rate (dropping amount) of one or more monomers may be dropped constantly (constant amount) from the start to the end of dropping, or may be dropped over time depending on the polymerization temperature or the like. The dropping speed (dropping amount) may be changed. Moreover, even if it does not dripping all the dripping components similarly, you may shift the start time and the end time for every dripping component, or you may shorten or extend dripping time. Thus, the manufacturing method of this invention can be changed suitably in the range which does not impair the effect of this invention. Moreover, when each component is dripped in the form of a solution, you may heat a dripped solution to the same extent as the polymerization temperature in a reaction system. In this way, when the polymerization temperature is kept constant, temperature variation is small and temperature adjustment is easy.

  When bisulfite is used as the initiator system, the molecular weight at the initial stage of polymerization has a great influence on the final molecular weight of bisulfite. Therefore, in order to lower the initial molecular weight, 5 to 20% by mass of bisulfite or a solution thereof is added (dropped) within 60 minutes, preferably within 30 minutes, more preferably within 10 minutes from the start of polymerization. desirable. In particular, as described later, this is effective when the polymerization is started from room temperature.

  Moreover, about the dripping time of a bisulfite or its solution in the case of using a bisulfite as an initiator system among the dripping components in the case of superposition | polymerization, from the completion | finish of dripping of a monomer (A) and (E) Is preferably 1 to 30 minutes, preferably 1 to 20 minutes, more preferably 1 to 15 minutes. Thereby, the amount of bisulfite after completion | finish of superposition | polymerization can be reduced, and generation | occurrence | production of sulfurous acid gas by this bisulfite and formation of an impurity can be suppressed effectively. For this reason, after the polymerization is completed, impurities formed by dissolving the sulfurous acid gas in the gas phase in the liquid phase can be significantly reduced. When bisulfite remains after the completion of the polymerization, impurities are generated, leading to deterioration of the performance of the polymer and precipitation of impurities when kept at a low temperature. Therefore, it is desirable that the initiator containing bisulfite is consumed and does not remain at the end of the polymerization.

  Here, in the case where the dropping end time of the bisulfite (solution) can be advanced by less than 1 minute from the dropping end time of the monomers (A) and (E), the bisulfite is added after the completion of the polymerization. May remain. In such a case, the end of dropping bisulfite or its solution and the end of dropping monomers (A) and (E) are simultaneous, or the end of dropping bisulfite (solution) is simpler. The case where it is later than the end of dropping of the monomers (A) and (E) is included. In such a case, it tends to be difficult to effectively and effectively suppress the generation of sulfurous acid gas and the formation of impurities, which may adversely affect the thermal stability of the polymer from which the remaining initiator is obtained. On the other hand, when the completion time of the addition of bisulfite or the solution thereof is more than 30 minutes earlier than the addition completion time of the monomers (A) and (E), the bisulfite is consumed by the end of the polymerization. I'm stuck. For this reason, the molecular weight tends to increase. In addition, during the polymerization, the dropping rate of bisulfite is higher than the dropping rate of the monomers (A) and (E), and a large amount is dropped in a short time. Tend to occur frequently.

  Moreover, in the case of using bisulfite as an initiator system among the dropping components during polymerization, the dropping end time of the persulfate (solution) is the dropping end time of the monomers (A) and (E). 1 to 30 minutes, preferably 1 to 20 minutes, more preferably 1 to 15 minutes. Thereby, the amount of monomer components remaining after the completion of polymerization can be reduced, and impurities caused by the remaining monomers can be significantly reduced.

  Here, in the case where the dropping end time of the persulfate (solution) can be delayed by less than 1 minute from the dropping end time of the monomers (A) and (E), the monomer component after the completion of the polymerization May remain. In such a case, the end of dropping of the persulfate (solution) and the end of dropping of the monomers (A) and (E) are simultaneous, or the end of dropping of the persulfate (solution) is simpler. The case where it is earlier than the end of dropping of the monomers (A) and (E) is included. In such a case, it tends to be difficult to effectively and effectively suppress the formation of impurities. On the other hand, in the case where the dropping end time of the persulfate (solution) is more than 30 minutes later than the dropping end time of the monomers (A) and (E), the persulfate or the decomposition product thereof is It may remain and form impurities.

(Polymerization time)
In the polymerization, even when bisulfite is used as an initiator system at a low polymerization temperature, it is more important to suppress the generation of sulfurous acid gas and prevent the formation of impurities. For this reason, it is preferable to make total dripping time in the case of superposition | polymerization 180-600 minutes, Preferably it is 210-480 minutes, More preferably, it is 240-420 minutes. When the total dropping time is less than 180 minutes, the effects of the persulfate solution and the bisulfite solution added as the initiator system tend to be reduced. Therefore, the amount of sulfur-containing groups such as sulfonic acid groups introduced into the terminal or side chain tends to decrease with respect to the resulting acrylic acid polymer. As a result, the weight average molecular weight of the polymer tends to increase. Moreover, it may occur that bisulfite exists excessively by being dripped in the reaction system in a short time. For this reason, such excessive bisulfite is decomposed to generate sulfurous acid gas, which may be released out of the system or may form impurities. However, it tends to be improved by carrying out the polymerization temperature and the initiator amount in a specific range that is low. On the other hand, when the total dropping time exceeds 600 minutes, the generation of sulfurous acid gas is suppressed, so that the resulting polymer has good performance. However, the productivity of the acrylic acid polymer is lowered, and the use application may be limited. The total dropping time here means the time from the start of dropping the first dropping component (not necessarily one component) to the completion of dropping the last dropping component (not necessarily one component).

(Polymerization concentration)
The solid content concentration in the aqueous solution (that is, the polymerization solid content concentration of the monomer) at the time when the dropping of the above components is completed and the polymerization reaction in the polymerization reaction system is completed is preferably 35% by mass or more, more preferably It is 40-70 mass%, More preferably, it is 45-65 mass%. Thus, if the solid content concentration at the end of the polymerization reaction is 35% by mass or more, the polymerization can be carried out at a high concentration and in one stage. Therefore, an acrylic acid polymer having a low molecular weight can be obtained efficiently. For example, the concentration step that was necessary in some cases in the conventional manufacturing method can be omitted. Therefore, the manufacturing efficiency can be greatly increased. As a result, the productivity of the acrylic acid polymer is greatly improved, and an increase in manufacturing cost can be suppressed.

  Here, when the solid formation concentration is less than 35% by mass, the productivity of the acrylic acid polymer may not be significantly improved. For example, it becomes difficult to omit the concentration step.

  When the solid content concentration is increased in the polymerization reaction system, the viscosity of the reaction solution increases remarkably with the progress of the polymerization reaction, and the weight average molecular weight of the resulting polymer tends to increase significantly. However, by performing the polymerization reaction on the acidic side (pH at 25 ° C. is 1 to 6 and the degree of neutralization is 1 to 25 mol%), the increase in the viscosity of the reaction solution accompanying the progress of the polymerization reaction is suppressed. can do. Therefore, a polymer having a low molecular weight can be obtained even when the polymerization reaction is carried out under a high concentration condition, and the production efficiency of the polymer can be greatly increased.

  Here, the time point when the polymerization reaction is completed may be a time point when the dropping of all of the dropping components is completed, but preferably refers to a time point when a predetermined aging time has elapsed (polymerization is completed). .

(Aging process)
The aging time is usually 1 to 120 minutes, preferably 5 to 60 minutes, more preferably 10 to 30 minutes. When the aging time is less than 1 minute, the monomer component may remain due to insufficient aging, which may cause impurities due to the residual monomer, resulting in performance degradation. On the other hand, when the aging time exceeds 120 minutes, the polymer solution may be colored. In addition, since the polymerization has already been completed, it is uneconomical to apply a further polymerization temperature.

  Further, during the aging, the polymerization temperature is applied because it is within the polymerization reaction period and is included in the polymerization. Therefore, the temperature here may also be maintained at a constant temperature (preferably the temperature at the end of dropping), or the temperature may be changed over time during aging. Therefore, the polymerization time refers to the above total dropping time + ripening time, and refers to the time required from the first titration start point to the ripening end point.

(Process after polymerization)
In the method for producing an acrylic acid polymer according to the present invention, the polymerization is preferably performed under acidic conditions as described above. Therefore, the neutralization degree (final neutralization degree) of the resulting acrylic acid polymer is set to a predetermined range by appropriately adding an appropriate alkaline component as a post-treatment as necessary after the polymerization is completed. May be.

  The final neutralization degree is not particularly limited because it varies depending on the intended use, and can be set in a very wide range of 1 to 100 mol%. For example, when used as a detergent builder for a weakly acidic detergent said to be gentle to the skin, it may be used without being neutralized while remaining acidic. Moreover, when using for neutral detergent, an alkaline detergent, etc., you may neutralize with an alkali component as a post-process, and you may use after neutralizing to 90 mol% or more of neutralization degree. In particular, the final neutralization degree when used as an acidic polymer is preferably 1 to 75 mol%, more preferably 5 to 70 mol%. When used as a neutral to alkaline polymer, the final neutralization degree is preferably 75 to 100 mol%, more preferably 85 to 99 mol%. Further, when the final neutralization degree when used as a neutral or alkaline polymer exceeds 99 mol%, the aqueous polymer solution may be colored.

  Examples of the alkali component include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide; ammonia, monoethanolamine, diethanolamine, Examples thereof include those represented by organic amines such as triethanolamine. Only one type of alkali component may be used, or a mixture of two or more types may be used.

In addition, when the reaction system is used without being neutralized as described above, since the inside of the reaction system is acidic, toxic sulfurous acid gas (SO ₂ gas) remains in the atmosphere in the reaction system. There may be. In such a case, it is desirable to decompose by adding a peroxide such as hydrogen peroxide or to expel it by introducing (blowing) air or nitrogen gas.

(Other manufacturing conditions)
The (meth) acrylic acid-based copolymer of the present invention may be produced in a batch manner or in a continuous manner.

<Use of polymer and polymer composition of the present invention>
The polymer (or polymer composition) of the present invention comprises a water treatment agent, fiber treatment agent, dispersant, detergent builder (or detergent composition), scale inhibitor (scale inhibitor), metal ion sealing agent, It can be used as a sticking agent, cement additive, various binders, emulsifiers, skin care agents, hair care agents and the like. As a detergent builder, it can be used by adding to detergents for various uses such as clothing, tableware, residential, hair, body, toothpaste, and automobile.

(Water treatment agent)
The polymer (or polymer composition) of the present invention can be used as a water treatment agent. If necessary, the water treatment agent may contain a polymerized phosphate, phosphonate, anticorrosive, slime control agent, and chelating agent as other compounding agents.

  The water treatment agent is useful for scale prevention in a cooling water circulation system, a boiler water circulation system, a seawater desalination apparatus, a reverse osmosis membrane treatment apparatus, a pulp digester, a black liquor concentration tank, and the like. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effects.

(Fiber treatment agent)
The polymer (or polymer composition) of the present invention can be used as a fiber treatment agent. The fiber treatment agent includes at least one selected from the group consisting of a dye, a peroxide, and a surfactant, and the polymer (or polymer composition) of the present invention.

  The content of the polymer of the present invention in the fiber treatment agent is preferably 1 to 100% by weight, more preferably 5 to 100% by weight, based on the entire fiber treatment agent. Further, any appropriate water-soluble polymer may be included as long as the performance and effects are not affected.

  Below, the compounding example of the fiber processing agent which is closer to embodiment is shown. This fiber treatment agent can be used in the steps of refining, dyeing, bleaching and soaping in fiber treatment. Examples of dyeing agents, peroxides and surfactants include those usually used for fiber treatment agents.

  The blending ratio of the copolymer of the present invention and at least one selected from the group consisting of a dye, a peroxide and a surfactant is, for example, for improving the whiteness, color unevenness, and dyeing tempering of the fiber. Includes 0.1 to 100 parts by weight of at least one selected from the group consisting of a dye, a peroxide, and a surfactant with respect to 1 part by weight of the polymer of the present invention in terms of a pure amount of the fiber treatment agent. It is preferable to use the composition mix | blended in this ratio as a fiber processing agent.

  Arbitrary appropriate fiber can be employ | adopted as a fiber which can use the said fiber processing agent. Examples thereof include cellulosic fibers such as cotton and hemp, chemical fibers such as nylon and polyester, animal fibers such as wool and silk, semi-synthetic fibers such as human silk, and woven fabrics and blended products thereof.

  When the fiber treatment agent is applied to the refining process, it is preferable to blend the polymer of the present invention with an alkali agent and a surfactant. When applied to the bleaching step, it is preferable to blend the copolymer of the present invention, a peroxide, and a silicic acid-based agent such as sodium silicate as a decomposition inhibitor for the alkaline bleaching agent.

(Inorganic pigment dispersant)
The polymer (or polymer composition) of the present invention can be used as an inorganic pigment dispersant. In the inorganic pigment dispersant, condensed phosphoric acid and its salt, phosphonic acid and its salt, and polyvinyl alcohol may be used as other compounding agents as required.

  The content of the polymer of the present invention in the inorganic pigment dispersant is preferably 5 to 100% by weight with respect to the whole inorganic pigment dispersant. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effect.

  The inorganic pigment dispersant can exhibit good performance as a dispersant for heavy or light calcium carbonate or clay inorganic pigment used in paper coating. For example, by adding a small amount of an inorganic pigment dispersant to an inorganic pigment and dispersing it in water, high concentration calcium carbonate having low viscosity and high fluidity and good aging stability of their performance. High concentration inorganic pigment slurries such as slurries can be produced.

  When the inorganic pigment dispersant is used as a dispersant for an inorganic pigment, the amount of the inorganic pigment dispersant used is preferably 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the inorganic pigment. When the amount of the inorganic pigment dispersant used is within the above range, a sufficient dispersion effect can be obtained, and an effect commensurate with the addition amount can be obtained, which can be economically advantageous.

(Cement additive)
The polymer (or polymer composition) of the present invention can be used as a cement additive. When used as a cement additive, it preferably has a structural unit represented by the following general formula (2) in addition to the structural unit represented by the general formula (1).

In the general formula (2), R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom or a methyl group. R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ^a is the same or different and represents an alkylene group having 2 to 18 carbon atoms. m represents the average addition mole number of the oxyalkylene group represented by R ^a O, and is a number of 1 to 300. X represents a divalent alkylene group having 1 to 5 carbon atoms, or, when the group represented by R ¹ R ³ C═CR ² — is a vinyl group, a carbon atom bonded to X, oxygen Indicates that atoms are directly bonded to each other.
When two or more oxyalkylene groups represented by — (R ^a O) — in the general formula (1) are present in the same unsaturated alcohol polyalkylene glycol adduct, — (R ^a O) — The represented oxyalkylene group may be in any addition form such as random addition, block addition, and alternate addition.
The oxyalkylene group represented by-(R ^a O)-is an alkylene oxide adduct having 2 to 18 carbon atoms, and the structure of such an alkylene oxide adduct is ethylene oxide, propylene oxide, butylene oxide, It is a structure formed by one or more of alkylene oxides such as isobutylene oxide, 1-butene oxide and 2-butene oxide. Among such alkylene oxide adducts, ethylene oxide, propylene oxide, and butylene oxide adducts are preferable. Furthermore, what is mainly ethylene oxide (50-100 mol% with respect to 100 mol% of all alkylene oxides) is still more preferable.
When used as a cement additive, the polymer of the present invention has a structure represented by the above general formula (1) (in terms of acid type) of 1 to 50% by mass relative to the structure derived from all monomers. It is preferable to contain 50 to 99% by mass of the structure represented by the formula (1).

(Detergent builder)
The polymer (or polymer composition) of the present invention can be used as a detergent builder. As a detergent builder, it can be used by adding to detergents for various uses such as clothing, tableware, residential, hair, body, toothpaste, and automobile.

(Detergent composition)
The polymer (or polymer composition) of the present invention can also be added to a detergent composition.

  The content of the copolymer in the detergent composition is not particularly limited. However, from the viewpoint that excellent builder performance can be exhibited, the content of the copolymer is preferably 0.1 to 15% by mass, more preferably 0.3%, based on the total amount of the detergent composition. It is 10 mass%, More preferably, it is 0.5-5 mass%.

  Detergent compositions used in detergent applications usually include surfactants and additives used in detergents. Specific forms of these surfactants and additives are not particularly limited, and conventionally known knowledge can be appropriately referred to in the detergent field. The detergent composition may be a powder detergent composition or a liquid detergent composition.

  The surfactant is one or more selected from the group consisting of an anionic surfactant, a nonionic surfactant, a cationic surfactant and an amphoteric surfactant. When two or more kinds are used in combination, the total amount of the anionic surfactant and the nonionic surfactant is preferably 50% by mass or more, more preferably 60% by mass with respect to the total amount of the surfactant. It is above, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more.

  Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl ether sulfate, alkenyl ether sulfate, alkyl sulfate, alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfonate. , Saturated fatty acid salt, unsaturated fatty acid salt, alkyl ether carboxylate, alkenyl ether carboxylate, amino acid type surfactant, N-acyl amino acid type surfactant, alkyl phosphate ester or salt thereof, alkenyl phosphate ester or Its salts are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these anionic surfactants.

  Nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, higher fatty acid alkanolamides or alkylene oxide adducts thereof, sucrose fatty acid esters, alkyl glycoxides, fatty acid glycerin monoesters. Esters, alkylamine oxides and the like are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these nonionic surfactants.

  As the cationic surfactant, a quaternary ammonium salt or the like is suitable. As the amphoteric surfactant, a carboxyl type amphoteric surfactant, a sulfobetaine type amphoteric surfactant, and the like are suitable. The alkyl group and alkenyl group in these cationic surfactants and amphoteric surfactants may be branched from an alkyl group such as a methyl group.

  The blending ratio of the surfactant is usually 10 to 60% by mass, preferably 15 to 50% by mass, more preferably 20 to 45% by mass, particularly preferably based on the total amount of the detergent composition. Is 25-40 mass%. If the surfactant content is too small, sufficient detergency may not be achieved, and if the surfactant content is too high, the economy may be reduced.

  Additives include anti-redeposition agent to prevent redeposition of contaminants such as alkali builder, chelate builder, sodium carboxymethyl cellulose, stain inhibitor such as benzotriazole and ethylene-thiourea, soil release agent, color transfer Inhibitors, softeners, alkaline substances for pH adjustment, fragrances, solubilizers, fluorescent agents, colorants, foaming agents, foam stabilizers, polishes, bactericides, bleaching agents, bleaching aids, enzymes, dyes A solvent or the like is preferable. In the case of a powder detergent composition, it is preferable to blend zeolite.

  The detergent composition may comprise other detergent builders in addition to the polymer (or polymer composition) of the present invention. Examples of other detergent builders include, but are not limited to, alkali builders such as carbonates, hydrogen carbonates, and silicates, tripolyphosphates, pyrophosphates, bow glass, nitrilotriacetate, ethylenediaminetetraacetate, Examples thereof include acid salts, (meth) acrylic acid copolymer salts, acrylic acid-maleic acid copolymers, chelate builders such as fumarate and zeolite, and carboxyl derivatives of polysaccharides such as carboxymethylcellulose. Examples of the counter salt used in the builder include alkali metals such as sodium and potassium, ammonium and amine.

  The total blending ratio of the additive and other builder for detergent is usually preferably 0.1 to 50% by mass with respect to 100% by mass of the cleaning composition. More preferably, it is 0.2-40 mass%, More preferably, it is 0.3-35 mass%, Most preferably, it is 0.4-30 mass%, Most preferably, it is 0.5-20 mass% or less. It is. If the additive / other detergent builder content is less than 0.1% by mass, sufficient detergent performance may not be achieved, and if it exceeds 50% by mass, the economy may be reduced.

  In addition, the concept of the above-mentioned detergent composition includes specific detergents such as synthetic detergents for household detergents, textile industry and other industrial detergents, hard surface cleaners, and bleaching detergents that enhance one of the components. Detergents that are only used are also included.

  When the detergent composition is a liquid detergent composition, the amount of water contained in the liquid detergent composition is usually preferably 0.1 to 75% by mass, more preferably based on the total amount of the liquid detergent composition. Is 0.2 to 70% by mass, more preferably 0.5 to 65% by mass, even more preferably 0.7 to 60% by mass, particularly preferably 1 to 55% by mass, Preferably it is 1.5-50 mass%.

When the detergent composition is a liquid detergent composition, the detergent composition preferably has a kaolin turbidity of 200 mg / L or less, more preferably 150 mg / L or less, and even more preferably 120 mg / L or less. Especially preferably, it is 100 mg / L or less, Most preferably, it is 50 mg / L or less.
(Measurement method of kaolin turbidity)
A sample (liquid detergent) uniformly stirred in a 50 mm square cell having a thickness of 10 mm was removed and air bubbles were removed. Then, a NDU2000 manufactured by Nippon Denshoku Co., Ltd. Kaolin turbidity: mg / L) is measured.
Proteases, lipases, cellulases, and the like are suitable as enzymes that can be incorporated into the cleaning composition. Of these, proteases, alkaline lipases, and alkaline cellulases that are highly active in an alkaline cleaning solution are preferred.
The amount of the enzyme added is preferably 5% by mass or less with respect to 100% by mass of the cleaning composition. If it exceeds 5% by mass, improvement in detergency cannot be seen, and the economy may be reduced.
As the alkali builder, silicate, carbonate, sulfate and the like are preferable. As the chelate builder, diglycolic acid, oxycarboxylate, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), STPP (sodium tripolyphosphate), citric acid and the like are preferable. Other water-soluble polycarboxylic acid-based polymers other than the copolymer in the present invention may be used.
The above detergent composition should be a detergent with excellent dispersibility, extremely high quality agent performance and excellent stability that is less likely to cause performance degradation when stored for a long time and precipitation of impurities when held at low temperatures. Can do.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.
The determination of the monomer and the measurement and evaluation of the weight average molecular weight of the copolymer were carried out according to the following methods.

<Measurement of S amount and total S amount contained in copolymer>
The amount of S before and after the dialysis treatment of the acrylic acid polymer obtained by polymerization was quantified by inductively coupled plasma (ICP) emission spectrometry. Here, the amount of S of the acrylic acid polymer before dialysis treatment was defined as “total amount of S”. Further, the amount of S in the acrylic acid polymer after the dialysis treatment was defined as “the amount of S contained in the polymer”. The dialysis method is as follows.

<Dialysis method>
(I) A suitable amount of water was added to the acrylic acid polymer obtained by polymerization to prepare an aqueous acrylic acid polymer solution having a solid content concentration of 30% by mass. 20 g of this was put into a dialysis membrane 40 cm (length) and sealed. For the dialysis membrane, Spectra / Por Membrane MWCO: 1000 fractional molecular weight 1000 (manufactured by SPECTRUM LABORATORIES INC) was used. In the present invention, any material having a fractional molecular weight comparable to that of the dialysis membrane may be used.
(Ii) This was immersed in 2000 g of water in a 2 liter beaker and stirred with a stirrer.
(Iii) After 6 hours, the dialysis membrane was taken out of the beaker, and the outside of the dialysis membrane was thoroughly washed with water, and then the contents of the dialysis membrane were taken out.
(Iv) What concentrated this with the evaporator was used as the acrylic acid-type polymer sample after a dialysis treatment.
In addition, as the acrylic acid polymer sample before dialysis treatment, the acrylic acid polymer obtained by polymerization in (i) above was concentrated using an evaporator in the same manner as in (iv) above. It was.

<Monomer determination method>
The measurement of the content of monomers and the like was performed using liquid chromatography under the following conditions.
Apparatus: L-7000 series detector manufactured by Hitachi, Ltd .: UV detector L-7400 manufactured by Hitachi, Ltd.
Column: Showa Denko Co., Ltd. Shodex RSpak DE-413L
Flow rate: 1.0 ml / min
Column temperature: 40 ° C
Mobile phase: 0.1% aqueous phosphoric acid solution.

<Measurement conditions of weight average molecular weight>
Equipment: Hitachi L-7000 series detector: RI
Column: SHODEX Asahipak GF-310-HQ, GF-710-HQ, GF-1G 7B manufactured by Showa Denko KK
Column temperature: 40 ° C
Flow rate: 0.5 ml / min
Calibration curve: POLYACRYLIC ACID STANDARD made by Soka Science Co., Ltd.
Eluent: 0.1N sodium acetate aqueous solution.
<Measurement of solid content>
Under a nitrogen atmosphere, the polymer of the present invention (polymer composition) of 1.0 g added with 1.0 g of water) was dried for 1 hour in an oven heated to 170 ° C. From the weight change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Viscosity of polymer composition>
Container: 500 ml glass beaker Temperature: 25 ° C
Viscometer, etc .: B-type viscometer, No. 3 rotors, 30 rpm.

<Anti-mold test>
The polymer composition was diluted to a solid content of 5% by mass and allowed to stand for 30 days so that it was not exposed to direct sunlight outdoors and rain did not enter. Thereafter, the occurrence of mold was evaluated visually and by smell.

<Recontamination prevention capability>
(1) A polyester cloth obtained from Test fabric was cut into 5 cm × 5 cm to prepare a white cloth. The whiteness of the white cloth was measured by reflectance using a colorimetric color difference meter SE2000 type manufactured by Nippon Denshoku Industries Co., Ltd. in advance.
(2) Hard water was prepared by adding pure water to 4.41 g of calcium chloride dihydrate to 15 kg.
(3) Pure water was added to 4.0 g of sodium linear alkylbenzene sulfonate, 6.0 g of sodium carbonate, and 2.0 g of sodium sulfate to make 100.0 g to prepare a surfactant aqueous solution.
(4) A targot meter is set at 25 ° C., 1 L of hard water, 5 g of an aqueous surfactant solution, 1 g of a 2% polymer aqueous solution in terms of solid content, 0.15 g of zeolite, and 0.25 g of carbon black are put in a pot, and 100 rpm For 1 minute. Then, 10 white cloths were put and stirred at 100 rpm for 10 minutes.
(5) Water of the white cloth was drained by hand, 1 L of tap water adjusted to 25 ° C. was put in the pot, and stirred at 100 rpm for 2 minutes. This was done twice.
(6) A white cloth was applied and dried while stretching the wrinkles with an iron, and then the whiteness of the white cloth was measured again with the above colorimetric colorimeter with reflectance.
(7) The recontamination prevention rate was calculated from the above measurement results using the following equation.
Recontamination prevention rate (%) = (whiteness after washing) / (whiteness of raw white cloth) × 100.

<Example 1>
Purify 350.0 g of pure water (initial charge) into a 5 liter SUS separable flask equipped with an external circulation cooling device equipped with a volumetric flowmeter (solution holding amount 170 ml), a reflux condenser and a stirrer. The temperature was raised by heating.
The external circulation device was operated at a flow rate of about 50 ml / min, and the solution temperature in the separable flask was set to about 90 ° C. At this time, the outlet temperature of the external circulation device was about 55 ° C. Thereafter, the solution temperature was maintained at about 90 ° C. by adjusting the flow rate within a range of ± 5 ml / min.
Next, an aqueous solution (hereinafter abbreviated as AA (1)) 900 containing 80% by mass of acrylic acid, 0.10% by mass of propionic acid and 0.18% by mass of acetic acid in a polymerization reaction system at a constant temperature of about 90 ° C. under stirring 900 0.0 g (10.0 mol), 48% sodium hydroxide aqueous solution (hereinafter abbreviated as 48% NaOH) 41.7 g (0.5 mol), 15% sodium persulfate aqueous solution (hereinafter abbreviated as 15% NaPS) 133.3 g (Conversion to monomer input amount (here, monomer input amount refers to all input amounts of monomer composition; hereinafter the same)) 2.0% / mol), 35% Sodium bisulphite aqueous solution (hereinafter abbreviated as 35% SBS) 142.9 g (5.0 g / mol when converted to monomer charge) was added dropwise from separate dropping nozzles. Each dropping time was set to AA (1), 48% NaOH for 300 minutes, 15% NaPS for 310 minutes, and 35% SBS for 290 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed.
After completion of the dropwise addition, the reaction solution was kept at 90 ° C. for an additional 30 minutes and aged to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 750.0 g (9.0 mol) of 48% NaOH was gradually added dropwise to the reaction solution while stirring to neutralize it. In this way, a polymer composition (1) (the polymer contained in the polymer (1)) having a solid content concentration of 45 mass% and a final neutralization degree of 95 mol% was obtained. Table 1 summarizes the weight average molecular weight (MW) of the polymer (1).
In addition, the mass% of propionic acid and acetic acid with respect to the acrylic acid polymer in the polymer composition (1) was as charged.

<Example 2>
In Example 1, the acrylic acid was changed to 900.0 g of an aqueous solution (AA (1)) containing 80% by mass of acrylic acid, 0.10% by mass of propionic acid, and 0.18% by mass of acetic acid, and 80% by mass of acrylic acid, A polymer composition (2) having a solid content concentration of 46% by mass was obtained in the same manner as in Example 1 except that 900.0 g of an aqueous solution containing 20 ppm of propionic acid and 0.2% by weight of acetic acid was used (included). Each copolymer is referred to as a polymer (2)).

<Example 3>
In Example 1, the acrylic acid was changed to 900.0 g of an aqueous solution (AA (1)) containing 80% by mass of acrylic acid, 0.10% by mass of propionic acid, and 0.18% by mass of acetic acid, and 80% by mass of acrylic acid, A polymer composition (3) having a solid content concentration of 46% by mass was obtained in the same manner as in Example 1 except that 900.0 g of an aqueous solution containing 0.2% by mass of propionic acid and 0.05% by mass of acetic acid was used. Obtained (each included copolymer is referred to as polymer (3)).

<Comparative Example 1>
In Example 1, 80% by mass of acrylic acid was changed to 900.0g of an aqueous solution (AA (1)) containing 80% by mass of acrylic acid, 0.10% by mass of propionic acid, and 0.18% by mass of acetic acid. In the same manner as in Example 1 except that 900.0 g of an aqueous solution (hereinafter abbreviated as 80% AA) of 0.2 ppm propionic acid and 0.003 mass% acetic acid was used, the solid content concentration was 45 mass%. A comparative polymer composition (1) was obtained (the comparative polymer contained is referred to as comparative polymer (1), respectively).

<Example 4>
The obtained polymer compositions (1) to (3) and the comparative polymer composition (1) were evaluated for viscosity, antifungal test, and anti-recontamination ability. The ability to prevent recontamination was also evaluated when no polymer was added. The results are shown in Table 1.

From the above, it is clear that the polymer composition of the present invention can maintain the ability to prevent recontamination and improve the handleability (decrease in viscosity) and the antifungal property as compared with the conventional polymer composition. Became.

  The polymer of the present invention can be suitably used for water-soluble polymer applications such as detergent builders and pigment dispersants because it exhibits excellent good handleability and anti-corrosion properties.

Claims (3)

(I) An acrylic acid polymer having a structural unit represented by the following general formula (1) as an essential component and having a weight average molecular weight of 2000 to 50000,
(Ii) an acrylic acid polymer composition containing propionic acid (salt) and acetic acid (salt),
An acrylic acid polymer composition, wherein the total content of propionic acid (salt) and acetic acid (salt) is 50 ppm or more and 0.5% by mass or less with respect to the acrylic acid polymer.

In the general formula (1), M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group. (I) An acrylic acid polymer having a structural unit represented by the following general formula (1) as an essential component and having a weight average molecular weight of 2000 to 50000,
(Ii) an acrylic acid polymer composition containing propionic acid (salt) and acetic acid (salt),
The total content of propionic acid (salt) and acetic acid (salt) is 50 ppm to 0.5% by mass with respect to the acrylic acid polymer, and the acrylic acid polymer is acrylic acid based on glycerin. Is produced by polymerizing as essential,
Acrylic acid polymer composition.

In the general formula (1), M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group. A method for producing an acrylic acid polymer characterized by polymerizing acrylic acid containing propionic acid (salt) and acetic acid (salt) as an essential component,
A method for producing an acrylic acid-based copolymer, wherein the total content of propionic acid (salt) and acetic acid (salt) is polymerized in the range of 50 ppm to 0.5% by mass with respect to the acrylic acid. .