JP2012116964A - (meth)acrylic acid-based polymer and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing a polymer (aqueous solution) which has excellent dispersibility etc. of an inorganic substance and outstanding color tone, even at an industrial level production.SOLUTION: The method for producing a (meth)acrylic acid-based polymer includes: (i) a step to polymerize a (meth)acrylic acid-based monomer in the presence of hypophosphorous acid (salt); and (ii) a step to add 0.05-1.5 g of hydrogen peroxide, based on 1 mole of the monomer to be used, to a reaction liquid during and/or after the polymerization of the (meth)acrylic acid-based monomer.

Description

The present invention relates to a method for producing a (meth) acrylic acid polymer. More specifically, the present invention relates to a (meth) acrylic acid polymer which is excellent in color tone and pigment dispersion performance.

A carboxyl group-containing polymer typified by sodium poly (meth) acrylate is widely used in applications such as detergent builders, pigment dispersants, water treatment agents (scale component adhesion inhibitors). In these markets, there is a demand for polymers that exhibit higher performance.

  As a method for satisfying such a demand, for example, Patent Document 1 discloses a compound containing calcium and the like in the range of 1 to 70 parts per 100 parts of a polymer of α and β monoethylenically unsaturated carboxylic acids. It is disclosed that a polymer maintained at a pH of 4 or higher exhibits a good pigment dispersion effect when added in a small amount.

  Further, for example, Patent Document 2 discloses a method for producing a water-soluble polymer in which a chain transfer agent is continuously added for a predetermined period during the polymerization period, and the addition rate of the chain transfer agent to the monomer is set at least once. Disclosed is a method for producing a water-soluble polymer, characterized in that the polymer obtained by the above method can reduce the amount of residual monomers, and the molecular weight distribution of the resulting polymer. It is disclosed that it can be made narrower and that it shows better dispersibility of calcium carbonate.

  Further, for example, in Patent Document 3, a monomer component composed of a monocarboxylic acid (salt) monoethylenically unsaturated monomer is polymerized in an aqueous solution at a high concentration using a polymerization catalyst in the presence of an alkaline substance. The persulfate and hydrogen peroxide are used in combination as the polymerization catalyst, and the total amount of the alkaline substance used is an amount necessary to neutralize all the acid groups of the monomer component. Low molecular weight (meth) acrylic acid (salt), characterized in that it is 99 mol% or less, and the dropping of the hydrogen peroxide is finished 10 minutes or more earlier than the dropping end time of the monomer component. A method for producing a polymer is disclosed, and it is disclosed that the polymer obtained by the above method exhibits a good pigment dispersibility.

  However, for example, when used in a dispersant for paper processing pigment slurry, in addition to the above performance, there is an increasing demand for a polymer composition with less coloring so as not to affect the whiteness of the paper.

JP 54-82416 A JP-A-2005-139469 Japanese Patent Laid-Open No. 2002-80502

In general, a (meth) acrylic acid (salt) -based polymer (aqueous solution) is colored by the influence of a trace component generated during polymerization in a heating step such as a polymerization step or a neutralization step. Furthermore, even when the coloring of the (meth) acrylic acid (salt) -based polymer (aqueous solution) after polymerization is suppressed, for example, when used for calcium carbonate dispersion slurry, the color tone of the calcium carbonate dispersion slurry is deteriorated. There is.
As described above, various (meth) acrylic acid (salt) -based polymers have been proposed, but no polymer having sufficient performance (for example, pigment dispersibility) and satisfactory color tone is known. . In particular, a method for producing a (meth) acrylic acid (salt) polymer that does not adversely affect the color tone of the calcium carbonate slurry when used for, for example, calcium carbonate slurry is not known.
The present invention is excellent in inorganic dispersibility and the like. For example, when used for calcium carbonate slurry, a polymer (aqueous solution) that does not adversely affect the color tone of calcium carbonate slurry and its dried product can be easily used even at an industrial level. Another object of the present invention is to provide a manufacturing method.

The present inventors have intensively studied to solve the above problems. As a result, when (meth) acrylic acid (salt) is polymerized in the presence of hypophosphorous acid (salt), a specific amount of hydrogen peroxide is added to the reaction liquid (polymerization liquid) during and / or after polymerization. By adding, it discovered that coloring of the (meth) acrylic acid (salt) type-polymer (aqueous solution) obtained became favorable, and came to complete the said invention.
That is, the method for producing a (meth) acrylic acid polymer aqueous solution according to the present invention comprises (i) a step of polymerizing a (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt), ii) during and / or after the polymerization of the (meth) acrylic acid monomer, adding 0.05 to 1.5 g of hydrogen peroxide to the reaction liquid with respect to 1 mol of the monomer used. And a process for producing a (meth) acrylic acid polymer.

According to the production method of the present invention, there is no adverse effect on the dispersibility of inorganic fine particles such as excellent mud stains and inorganic pigments and the color tone of calcium carbonate slurry and its dried product when used for calcium carbonate slurry (meta). An acrylic acid polymer aqueous solution can be produced efficiently.

Hereinafter, the present invention will be described in detail.

[Production method of (meth) acrylic acid polymer (aqueous solution)]
<Step of adding hydrogen peroxide>
The method for producing a (meth) acrylic acid polymer aqueous solution according to the present invention comprises (i) a step of polymerizing a (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt), and (ii) Adding 0.05 to 1.5 g of hydrogen peroxide to the reaction liquid with respect to 1 mol of the monomer used during and / or after the polymerization of the (meth) acrylic acid monomer, This is a method for producing a (meth) acrylic acid polymer.
In the present invention, the (meth) acrylic acid polymer refers to a polymer containing a structure derived from (meth) acrylic acid (salt). The structure derived from (meth) acrylic acid (salt) is a structure formed by radical polymerization of (meth) acrylic acid (salt), and is a structure represented by —CH ₂ CR (COOM) —. is there. In the structure, R represents a hydrogen atom or a methyl group, and M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt.
In the present invention, (meth) acrylic acid (salt) refers to acrylic acid, acrylate, methacrylic acid, and methacrylate, and the salt represents a metal salt, an ammonium salt, or an organic amine salt.

  In the production method of the present invention, 0.05 to 1.5 g of hydrogen peroxide is used as a reaction solution for 1 mol of the monomer used during and / or after polymerization of the (meth) acrylic acid monomer. And a step of adding. Here, “during polymerization” represents any time or period from the start of polymerization to the end of polymerization. Here, “at the start of polymerization” means that a reaction apparatus (reaction kettle) has a part or all of a polymerization initiator used for polymerization and a part or all of a (meth) acrylic acid monomer used for polymerization. Refers to the time when is first added. “At the end of polymerization” represents the time when the addition of the entire amount of monomers used for the polymerization to the reaction apparatus (reaction vessel) is completed. “After polymerization” represents a period after the end of polymerization.

In the production method of the present invention, the hydrogen peroxide includes a step of adding the (meth) acrylic acid monomer to the reaction liquid during and / or after the polymerization. It is preferable to include a step of adding hydrogen peroxide within 3 hours from the end of the polymerization because the color tone of the calcium carbonate slurry is improved when used for calcium carbonate slurry. It is particularly preferable to include the step of adding.
In the case where the production method of the present invention includes a step of adding after the polymerization, and when the neutralization step is included after the polymerization, the color tone of the calcium carbonate slurry becomes favorable when used for the calcium carbonate slurry application. It is preferable to start the step of adding hydrogen peroxide before starting the summing step.

  In the production method of the present invention, when used for calcium carbonate slurry, the calcium carbonate slurry and the color tone after drying the slurry are improved, so that the (meth) acrylic acid monomer is hydrogenated during polymerization. However, it is preferable to add hydrogen peroxide in a time period of 30% or more and 100% or less of the entire polymerization time (the time from the start of polymerization to the end of polymerization). More preferably, it is more preferably added in a time zone of 50% or more and 100% or less, and particularly preferably added in a time zone of 70% or more and 100% or less. Of course, it is possible to add hydrogen peroxide in addition to during the polymerization, for example, before the polymerization, after the polymerization (for example, in the aging step, neutralization step, etc., if applicable). It is.

Hydrogen peroxide can be added to the reaction kettle as it is, but it is preferably diluted in the form of an aqueous solution.
The amount of hydrogen peroxide added during the polymerization (i) is preferably 0.05 to 1.5 g, preferably 0.07 to 1.0 g, per 1 mol of (meth) acrylic acid (salt) used. Is more preferable, and 0.09 to 0.8 g is particularly preferable. Calcium carbonate when (meth) acrylic acid (salt) is used in a calcium carbonate slurry when the amount of hydrogen peroxide added is less than 0.05 g per 1 mol of (meth) acrylic acid (salt) used The coloration of the slurry may not be sufficiently low. On the other hand, if the added amount of hydrogen peroxide exceeds 1.5 g, the molecular weight distribution of (meth) acrylic acid (salt) becomes wide due to the influence on chain transfer to hydrogen peroxide, and the dispersibility of calcium carbonate is increased. It tends to decrease.

<Step of polymerizing (meth) acrylic acid (salt)>
(Monomer)
The production method of the present invention includes a step of polymerizing the (meth) acrylic acid (salt). In the production method of the present invention, only (meth) acrylic acid (salt) may be polymerized, but other monomers copolymerizable with (meth) acrylic acid (salt) may be copolymerized. Absent.
Specific examples of other monomers include maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methyleneglutaric acid, and carboxyl group-containing monomers other than acrylic acid such as salts thereof; 2-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, α-hydroxymethylethyl (meth) Hydroxyl group-containing alkyl (meth) acrylates such as acrylates; (meth) methacrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate ) Este of alkyl group having 1 to 18 carbon atoms of acrylic acid Alkyl (meth) acrylates; amino group-containing acrylates such as dimethylaminoethyl (meth) acrylate or quaternized products thereof; amide group-containing monomers such as (meth) acrylamide, dimethylacrylamide, and isopropylacrylamide; acetic acid Vinyl esters such as vinyl; Alkenes such as ethylene and propylene; Aromatic vinyl monomers such as styrene; Maleimide derivatives such as maleimide, phenylmaleimide and cyclohexylmaleimide; Vinyl-containing vinyl systems such as (meth) acrylonitrile Monomers; monomers having a sulfonic acid group such as 3-allyloxy-2-hydroxypropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid and their salts; Aldehyde group-containing vinyl monomers such as (meth) acrolein such as monomers having phosphonic acid groups such as phonic acid and (meth) allylphosphonic acid; alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and butyl vinyl ether; Vinyl chloride, vinylidene chloride, allyl alcohol: other functional group-containing monomers such as vinyl pyrrolidone; polyalkylene glycol (meth) acrylate, monoalkoxy polyalkylene glycol (meth) acrylate, vinyl alcohol, (meth) allyl alcohol, isoprenol A polyalkylene glycol chain-containing monomer such as a monomer having a structure in which 1 to 300 mol of alkylene oxide is added to an unsaturated alcohol such as Also about these other monomers, only 1 type may be used independently and 2 or more types may be used together.

  In the production method of the present invention, 80% by mass of (meth) acrylic acid (salt) in terms of acid type with respect to 100% by mass of all monomers ((meth) acrylic acid (salt) and other monomers). % Or more is preferable. If it is 80 mass% or more, it exists in the tendency for the pigment dispersion performance with time of the polymer (aqueous solution) obtained to improve. Here, acid type conversion means calculating a mass ratio (% by mass) using a salt type monomer (or structural unit) as a corresponding acid type monomer (or structural unit), for example, acrylic acid. If it is sodium, a mass ratio will be calculated as acrylic acid.

(Polymerization initiator)
The (meth) acrylic acid polymer of the present invention is obtained by polymerizing a monomer composition containing (meth) acrylic acid (salt) as an essential component in the presence of a polymerization initiator (also referred to as an initiator). Can do.
Known polymerization initiators can be used such as persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; dimethyl 2,2′-azobis (2-methylpropionate), 2 2,2′-azobis (2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanovaleric acid, azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvalero) 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. These polymerization initiators may be used alone or in the form of a mixture of two or more.
It is also possible to use hydrogen peroxide as a polymerization initiator. However, since the remaining amount of (meth) acrylic acid (salt) in the polymerization liquid increases, it is preferable to use a polymerization initiator other than hydrogen peroxide in combination.
The amount of the polymerization initiator (excluding hydrogen peroxide) is preferably 15 g or less, more preferably 0.1 to 12 g, based on 1 mol of all monomer components, unless otherwise specified.

  Among the above polymerization initiators, it is preferable to use a persulfate as one that does not significantly affect the dispersibility of the pigment in the resulting aqueous (meth) acrylic acid polymer solution. However, since the dispersibility of the pigment over time is improved, the amount of persulfate used is preferably 1.9 g or less, and preferably 1.6 g or less, based on 1 mol of all monomers. More preferred is 1.2 g or less, and particularly preferred is 1.1 g or less. The lower limit of the amount of persulfate used is preferably 0.1 g or more, more preferably 0.5 g or more, per 1 mol of all monomers.

  The method for adding the polymerization initiator is not particularly limited, but the amount dripped substantially continuously with respect to the total amount used is preferably 50% by weight or more of the required predetermined amount, particularly preferably 80% by weight. %, And it is most preferable to add the whole amount dropwise. The polymerization initiator is preferably dripped continuously, but the dripping speed may be changed.

  Although there is no particular limitation on the dropping time, in the case of an initiator that decomposes relatively quickly, such as persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate under the conditions of polymerization temperature and pH at the time of polymerization described later. It is preferable to drop until the monomer dropping end time, more preferably within 30 minutes after completion of the monomer dropping, and within 3 to 20 minutes after the monomer dropping. Particularly preferred. Thereby, the effect which can reduce the residual amount of the monomer in a polymer remarkably can be found. It should be noted that, even if the addition of these initiators is completed before the completion of the monomer addition, it does not particularly adversely affect the polymerization, and is set according to the residual amount of the monomer in the obtained polymer. It ’s good.

  For these initiators that are relatively quick to decompose, the preferred range is described only for the dropping end time, but the dropping start time is not limited at all and may be set as appropriate. For example, in some cases, the dropping of the initiator may be started before the start of dropping of the monomer, or in the case of a combined system in particular, the dropping of one initiator is started and a certain time has elapsed. Then, or after completion, another initiator may be dropped. Any of these may be set as appropriate according to the decomposition rate of the initiator and the reactivity of the monomer.

(Chain transfer agent)
Although the manufacturing method of the (meth) acrylic acid type polymer aqueous solution concerning this invention makes it essential to include the process of superposing | polymerizing a (meth) acrylic-acid type monomer in presence of hypophosphorous acid (salt). Hypophosphorous acid (salt) usually acts as a chain transfer agent.
By including the step of polymerizing the (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt), the dispersibility of the resulting polymer pigment is improved. Hypophosphorous acid (salt) refers to hypophosphorous acid, metal salts of hypophosphorous acid, ammonium salts, organic amine salts, hydrates thereof, and the like.
Polymerization of (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt) means that hypophosphorous acid is added to the reaction liquid (polymerization liquid) during polymerization of (meth) acrylic acid monomer. (Salt) is present, and hypophosphorous acid (salt) is present in the time period from 30% to 100% of the entire polymerization time (the time from the start of polymerization to the end of polymerization). It is preferable. More preferably, it exists in the time zone of 70% or more and 100% or less of the entire polymerization time. Of course, it may continue to exist after another time period, for example, after the end of polymerization.
Regarding the addition of hypophosphorous acid (salt) to the polymerization system (reaction solution), it may be added before the start of polymerization (so-called initial charge) or during the polymerization.

Since the dispersibility of the pigment over time is improved, the amount of hypophosphorous acid (salt) used is preferably 5.0 g or less, and 4.5 g or less, based on 1 mol of all monomers. The lower limit of the amount used is preferably 1.0 g or more, more preferably 1.5 g or more, based on 1 mol of all monomers.
When the amount of hypophosphorous acid (salt) used exceeds the above upper limit with respect to 1 mol of all monomers, hypophosphorous acid salt that does not contribute to chain transfer (hypophosphorous acid (not incorporated into the polymer terminal) ( The salt)) increases and the amount of inorganic anions increases, which may reduce the dispersive power over time.

The (meth) acrylic acid polymer of the present invention can use a chain transfer agent in addition to the above hypophosphorous acid (salt).
The chain transfer agent that can be used in this case is not particularly limited as long as it is a compound capable of adjusting the molecular weight, and a known chain transfer agent can be used. Specifically, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, 2-mercaptoethanesulfonic acid, n -Thiol chain transfer agents such as dodecyl mercaptan, octyl mercaptan, butylthioglycolate; Halides such as carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane; Secondary alcohols such as isopropanol, glycerin; Acids, phosphites, and hydrates thereof; sodium bisulfite (NaHSO ₃ ), potassium bisulfite, sodium dithionite (Na ₂ S ₂ O ₄ ), potassium dithionite, metabisulfite sodium (Na S 2 _{O 5),} bisulfite (salt) such as potassium metabisulfite; such, 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.
The addition amount in the case of using a chain transfer agent (excluding hydrogen peroxide) is, for example, 1 to 20 g, more preferably 2 to 15 g, per 1 mol of all monomer components. If the amount is less than 1 g, the effect of adding the chain transfer agent may not be sufficiently exhibited. Conversely, if the amount exceeds 20 g, the chain transfer agent may remain or the purity of the polymer may decrease.

(Decomposition catalyst, reducing compound)
The (meth) acrylic acid polymer of the present invention is produced by using a polymerization initiator decomposition catalyst or a reducing compound (also called a reaction accelerator) (added to the polymerization system) in addition to the polymerization initiator. May be.

As a compound that acts as a decomposition catalyst for the polymerization initiator or a reducing compound, heavy metal ions (or heavy metal salts) can be mentioned. That is, the polyacrylic acid polymer of the present invention may be produced by using (adding to the polymerization system) heavy metal ions (or heavy metal salts) in addition to the polymerization initiator and the like. In the present invention, the heavy metal ion means a metal having a specific gravity of 4 g / cm ³ or more. As said metal ion, iron, cobalt, manganese, chromium, molybdenum, tungsten, copper, silver, gold, lead, platinum, iridium, osmium, palladium, rhodium, ruthenium etc. are preferable, for example. These heavy metals can be used alone or in combination of two or more. Among these, iron is more preferable. The ionic valence of the heavy metal ions is not particularly limited. For example, when iron is used as the heavy metal, the iron ions in the initiator may be Fe ²⁺ or Fe ³⁺ , and these may be combined. May be.
In the present invention, the heavy metal ions are present in the reaction system by adding an aqueous solution or an aqueous solution in which a heavy metal salt (heavy metal compound) is dissolved to the polymerization system. The heavy metal salt used in that case should just contain the heavy metal ion desired to contain in an initiator, and can be determined according to the initiator to be used. When iron is used as the heavy metal ion, the mole salt (Fe (NH ₄ ) ₂ (SO ₄ ) ₂ · 6H ₂ O), ferrous sulfate · 7 hydrate, ferrous chloride, ferric chloride, etc. It is preferable to use a heavy metal salt or the like. Moreover, when using manganese as a heavy metal ion, manganese chloride etc. can be used suitably. When these heavy metal salts are used, since they are water-soluble compounds, they can be used in the form of an aqueous solution and have excellent handleability. In addition, the solvent of the solution formed by dissolving the heavy metal salt is not limited to water, and in the production of the (meth) acrylic acid polymer of the present invention, unless it significantly hinders the polymerization reaction, It can be used as long as the solubility of the heavy metal salt is not impaired.

  The heavy metal ions are added to the polymerization system as an aqueous solution or aqueous solution of a heavy metal salt. In the production method of the present invention, the heavy metal salt includes a heavy metal salt and a carboxyl group-containing compound when fed into the polymerization system. It is preferably supplied as an aqueous solution. When the heavy metal salt is supplied to the polymerization system as an aqueous solution containing the heavy metal salt and the carboxyl group-containing compound, the effect of heavy metal ions can be stably exhibited. There is little variation, and there is an effect that a polymer having a desired molecular weight can be stably produced. The “polymerization system” means the inside of a reaction vessel in which a polymerization reaction is carried out or is being carried out, and usually means an initially charged polymerization solvent or a polymerization solution during polymerization. When the heavy metal salt and the carboxyl group-containing compound are included, the ratio of the heavy metal salt and the carboxyl group-containing compound is preferably 1 to 100 parts by mass, more preferably 10 to 80 parts by mass with respect to 100 parts by mass of the heavy metal salt. is there.

  The heavy metal salt aqueous solution added to the polymerization system is preferably set so that the pH of the aqueous solution is 8 or less, more preferably 7 or less, and 6 or less. Is particularly preferred.

  The carboxyl group-containing compound is an organic compound having a carboxyl group, for example, acetic acid, propionic acid, butyric acid, formic acid, oxalic acid, succinic acid, glycolic acid, glyoxylic acid, etc., but from the viewpoint of reducing impurities, A compound having a polymerizable unsaturated double bond is preferred, and examples thereof include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methyleneglutaric acid and the like, and anhydrides thereof.

  The content of the heavy metal ions is preferably 0.1 to 10 ppm with respect to the total mass of the polymerization reaction solution at the completion of the polymerization reaction. If the content of heavy metal ions is less than 0.1 ppm, the effect of heavy metal ions may not be sufficiently exhibited. On the other hand, if the content of heavy metal ions exceeds 10 ppm, the color tone of the resulting polymer may be deteriorated. Moreover, when there is much content of heavy metal ion, when using the polymer which is a product, for example as a detergent builder, there exists a possibility of causing the stain | pollution | contamination of a builder for detergents.

The time when the polymerization reaction is completed means the time when the polymerization reaction is substantially completed in the polymerization reaction solution and a desired polymer is obtained. For example, when the polymer polymerized in the polymerization reaction solution is subsequently neutralized with an alkali component, the content of heavy metal ions is calculated based on the total mass of the polymerization reaction solution after neutralization. When two or more kinds of heavy metal ions are included, the total amount of heavy metal ions may be in the above range.
The concentration of the heavy metal compound in the aqueous solution or aqueous solution obtained by dissolving the heavy metal compound added to the polymerization system is preferably 0.1% by mass to 10% by mass.

  Examples of the polymerization initiator decomposition catalyst other than heavy metal ions (heavy metal salts) include metal halides such as lithium chloride and lithium bromide; metal oxides such as titanium oxide and silicon dioxide; hydrochloric acid, hydrobromic acid, Metal salts of inorganic acids such as perchloric acid, sulfuric acid and nitric acid; Carboxylic acids such as formic acid, acetic acid, propionic acid, lactic acid, isolacric acid, benzoic acid, their esters and their metal salts; pyridine, indole, imidazole, carbazole, etc. And heterocyclic amines thereof and derivatives thereof. These decomposition catalysts may be used alone or in combination of two or more.

  Examples of reducing compounds other than heavy metal ions (heavy metal salts) include, for example, boron trifluoride ether adducts, inorganic compounds such as perchloric acid; sulfur dioxide, bisulfite, sulfate, thiosulfate, sulfoxy Sulfur-containing compounds such as acid salts, benzenesulfinic acid and its substitutes, and homologues of cyclic sulfinic acids such as p-toluenesulfinic acid; octyl mercaptan, dodecyl mercaptan, mercaptoethanol, α-mercaptopropionic acid, thioglycolic acid, thiopropion Mercapto compounds such as acid, α-thiopropionic acid sodium sulfopropyl ester, α-thiopropionic acid sodium sulfoethyl ester; nitrogen-containing compounds such as hydrazine, β-hydroxyethylhydrazine, hydroxylamine; formaldehyde, acetaldehyde, Propionic aldehyde, n- butyraldehyde, isobutyraldehyde, aldehydes such as isovaleric aldehyde; ascorbic acid and the like. These reducing compounds may also be used alone or in combination of two or more. A reducing compound such as a mercapto compound may be added as a chain transfer agent.

  In the method for producing the (meth) acrylic acid polymer of the present invention, in addition to the polymerization initiator, the chain transfer agent, and the reaction accelerator, a pH adjuster, a buffering agent, and the like can be used as necessary.

(Polymerization solution)
The (meth) acrylic acid polymer of the present invention is preferably produced by solution polymerization. The solvent that can be used in this case is preferably a mixed solvent or water in which 50% by mass or more of water is water based on the total solvent. When only water is used, it is preferable in that the solvent removal step can be omitted. In addition, when the above chain transfer agent is used, the solvent itself is difficult to chain transfer in order to increase chain transfer efficiency (incorporate more chain transfer agent into the polymer terminal) and reduce inorganic anions as impurities. Those are preferred. From this point of view, it is preferable to use only water as a solvent or to reduce the amount of use as much as possible when an organic solvent is used in combination.
From the above viewpoint, for example, even when an organic solvent is used, it is preferably 10% by mass or less, more preferably 5% by mass or less, with respect to 100% by mass of the reaction solution after the completion of polymerization. More preferably, it is 1 mass% or less.
Here, as a solvent that can be used together with water at the time of polymerization, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; glycerin; polyethylene glycol; amides such as dimethylformaldehyde; ethers such as diethyl ether and dioxane are preferable. It is. These may be used alone or in combination of two or more.

  The polymerization reaction preferably has a solid content concentration after completion of the polymerization (the concentration of the non-volatile content in the solution, measured by the measurement method described later) of 10 to 60% by mass with respect to 100% by mass of the polymerization solution. 15-50 mass% is still more preferable, and 20-45 mass% is especially preferable.

(Other polymerization conditions)
The (meth) acrylic acid polymer of the present invention can employ any polymerization method of batch type (batch type), continuous type, and semi-continuous type. As conditions for producing the polyacrylic acid polymer of the present invention, a known polymerization method or a modified method of a known method can be used in addition to the above method, unless otherwise specified.

  The temperature during the polymerization is preferably 70 ° C. or higher, more preferably 75 to 110 ° C., and further preferably 80 to 105 ° C. If the temperature at the time of polymerization is in the above range, the residual monomer component is reduced and the dispersibility of the polymer tends to be improved. The temperature at the time of polymerization need not always be kept constant during the progress of the polymerization reaction. For example, the polymerization is started from room temperature, and the temperature is increased to a set temperature at an appropriate temperature increase time or temperature increase rate. Thereafter, the set temperature may be maintained, or the polymerization temperature may be varied (increased or decreased) over time during the course of the polymerization reaction, depending on the dropping method of the monomer component, initiator, and the like. Also good.

  The pressure in the reaction system may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure, but from the viewpoint of the molecular weight of the polymer obtained, the reaction system is sealed under normal pressure. However, it is preferably performed under pressure. Moreover, it is preferable to carry out under normal pressure (atmospheric pressure) in terms of equipment such as a pressurizing device, a decompressing device, a pressure-resistant reaction vessel, and piping. The atmosphere in the reaction system may be an air atmosphere, but is preferably an inert atmosphere. For example, the inside of the system is preferably replaced with an inert gas such as nitrogen before the start of polymerization.

(Neutralization rate during polymerization)
The method for producing the (meth) acrylic acid polymer (aqueous solution) of the present invention is such that the neutralization rate at the end of polymerization (ratio of neutralized acid groups to total acid groups (neutralized and unneutralized)) is Although any of 0-100 mol% is possible, 0-35 mol% is preferable and 0-10% is more preferable. If it is the said range, it exists in the tendency for the pigment dispersion performance with time of the polymer (aqueous solution) obtained and the color tone of aqueous solution to improve.

<Neutralization process>
The method for producing a (meth) acrylic acid polymer (aqueous solution) of the present invention may include a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized (meth) acrylic acid type polymer. good. The neutralization rate at the end of the neutralization step (ratio of acid groups neutralized with respect to all acid groups (neutralized and unneutralized)) may be 100 mol%, but is 0 to 99 mol%. 0 to 98 mol% is more preferable, and 0 to 97 mol% is particularly preferable. If it is the said range, it exists in the tendency for the pigment dispersion performance with time of the polymer (aqueous solution) obtained and the color tone of aqueous solution to improve.
The neutralization process may be performed in one stage, but may be performed in two or more stages.

Examples of neutralizing agents that can be used in the neutralization step include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates such as sodium carbonate, potassium carbonate, and sodium bicarbonate; water Hydroxides of alkaline earth metals such as calcium oxide and magnesium hydroxide; ammonia; amines such as monoethanolamine, monopropanolamine, diethanolamine and triethanolamine; ammonia such as ammonium bicarbonate; carbonates of amines; Illustrated.
A neutralization process is performed at 40 to 105 degreeC, for example.

<(Meth) acrylic acid polymer>
The (meth) acrylic acid polymer produced by the production method of the present invention (also referred to as the (meth) acrylic acid polymer of the present invention) includes a structural unit derived from (meth) acrylic acid (salt). The structural unit derived from (meth) acrylic acid (salt) is as described above, and is a structure in which the carbon-carbon double bond of (meth) acrylic acid (salt) is a single bond, such as acrylic acid. If it is a structural unit derived from, it is a structural unit represented by —CH ₂ CH (COOH) —.
In addition, that the (meth) acrylic acid polymer of the present invention has “structural units derived from (meth) acrylic acid (salt)” means that the finally obtained polymer has the structural units. means. That is, the “structural unit derived from (meth) acrylic acid (salt)” in the present invention is introduced into the polymer by copolymerizing the above (meth) acrylic acid (salt) with other monomer components. In addition to those obtained, for example, those in which the formation process extends before and after the polymerization reaction are also included, such as those obtained by first forming a structural unit derived from (meth) acrylic acid ester by copolymerization and then hydrolyzing it. .
(Meth) acrylic acid (salt) based on 100% by mass of the structure derived from all monomers ((meth) acrylic acid (salt) and other monomers) contained in the (meth) acrylic acid polymer of the present invention The composition of the derived structural unit (in terms of acid type) is preferably 80% by mass or more and 100% by mass or less. If it is 80 mass% or more, the pigment dispersion performance with time of the polymer aqueous solution tends to be improved. More preferably, it is 90 to 100 mass%, More preferably, it is 95 to 100 mass%.
Here, acid type conversion is as described above. The structure derived from (meth) acrylic acid (salt) in the (meth) acrylic acid polymer of the present invention is preferably a structure derived from acrylic acid (salt).

  The (meth) acrylic acid polymer of the present invention may have only a structure derived from (meth) acrylic acid (salt), but other copolymerizable with (meth) acrylic acid (salt). A structure derived from a monomer may be included. Examples of other monomers include those exemplified above.

The (meth) acrylic acid polymer of the present invention preferably contains a structure derived from hypophosphorous acid (salt) in the molecule because dispersibility of inorganic particles over time is improved. The composition of the structure derived from hypophosphorous acid (salt) contained in the (meth) acrylic acid polymer of the present invention is 0.5 to 8 mass relative to the (meth) acrylic acid polymer (acid type conversion). % (Acid type conversion) is preferable. The structure derived from hypophosphorous acid (salt) is specifically a hypophosphite group. For example, if it is a structural unit derived from sodium hypophosphite (phosphinic acid), a phosphinic acid group, -PH ( = O) (ONa), -P (= O) (ONa)-. Hypophosphite group can be measured by ³¹ P-NMR.

  The (meth) acrylic acid polymer aqueous solution produced by the production method of the present invention contains a (meth) acrylic acid polymer (also referred to as the (meth) acrylic acid polymer of the present invention).

Specifically, the weight average molecular weight of the (meth) acrylic acid polymer of the present invention is preferably 3000 to 50000, more preferably 4000 to 30000, and still more preferably 5000 to 20000. When the value of the weight average molecular weight is too large, the viscosity becomes high and handling may be complicated. On the other hand, if the value of the weight average molecular weight is too small, the dispersibility of clay, pigment, and the like is lowered, and there is a possibility that sufficient performance as a detergent builder or a pigment dispersant may not be exhibited. In addition, the value measured by the method as described in the Example mentioned later shall be employ | adopted as a value of the weight average molecular weight of the (meth) acrylic-acid type polymer of this invention.
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic acid polymer of the present invention is preferably 1.1 to 3.0, more preferably. It is 1.5 to 2.8, more preferably 1.8 to 2.6.
If the value of this molecular weight distribution is too small, for example, when a (meth) acrylic acid polymer is used as an inorganic dispersant, the slurry viscosity immediately after pulverization when the inorganic substance is wet pulverized may increase. If it is too large, the viscosity stability of the slurry over time may be reduced. In addition, the value measured by the method as described in the Example mentioned later shall be employ | adopted as a value of the molecular weight distribution of the (meth) acrylic-acid type polymer of this invention.

<(Meth) acrylic acid polymer aqueous solution>
The (meth) acrylic acid-based polymer aqueous solution of the present invention contains the (meth) acrylic acid-based polymer of the present invention as essential, as well as unreacted (meth) acrylic acid (salt), unreacted other Monomers, unreacted polymerization initiators, decomposition products of polymerization initiators, and the like.
The (meth) acrylic acid polymer aqueous solution of the present invention preferably contains 1 to 70% by mass of the (meth) acrylic acid polymer of the present invention with respect to 100% by mass of the polymer aqueous solution.
The content of unreacted monomers present in the aqueous polymer solution (total content of (meth) acrylic acid (salt) and other monomers) varies depending on the type of monomer used. The content of the polymer composition is preferably less than 1% by mass with respect to 100% by mass of the solid content. More preferably it is less than 0.5%, particularly preferably less than 0.1%.

  The (meth) acrylic acid polymer aqueous solution referred to in the present application is not particularly limited, but after producing a (meth) acrylic acid polymer in an aqueous solvent described later, it is subjected to a purification step such as impurity removal. Although what you manufacture may be sufficient, from a viewpoint of production efficiency, Preferably, what is obtained without passing through a refinement | purification process is preferable. Furthermore, after the polymerization step, the obtained polymerization aqueous solution is diluted with a small amount of water for handling convenience or the like (about 1 to 400% by mass with respect to 100% by mass of the obtained polymer aqueous solution), The concentrated product is also included in the (meth) acrylic acid polymer aqueous solution referred to in this application.

  The aqueous solution of the (meth) acrylic acid polymer of the present invention contains a solvent essentially containing water in addition to the (meth) acrylic acid polymer of the present invention. In that case, the content of the solvent is preferably about 30 to 99% by mass with respect to 100% by mass of the (meth) acrylic acid polymer aqueous solution.

  As will be described later, it is preferable that the content of the organic solvent is reduced as much as possible from the viewpoint of the use of the (meth) acrylic acid polymer aqueous solution or from the viewpoint of improving the performance. For example, the (meth) acrylic acid polymer 10 mass% or less is preferable with respect to 100 mass% of aqueous solution, 5 mass% or less is preferable, and 1 mass% or less is preferable.

In the (meth) acrylic acid polymer aqueous solution of the present invention, the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is preferably 1000 to 10,000 ppm with respect to the aqueous solution. If the concentration of the inorganic anion containing a sulfur atom or phosphorus atom is 10,000 ppm or less, the pigment dispersion performance with time of the polymer aqueous solution tends to be improved. If the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is set to less than 1000 ppm, it becomes difficult to produce an aqueous polymer aqueous solution having excellent pigment dispersion performance over time. Examples of inorganic anions containing sulfur atoms or phosphorus atoms include sulfate ions, sulfite ions, phosphate ions, phosphite ions, hypophosphite ions, and the like.
The aqueous polymer solution preferably has an inorganic anion concentration containing a sulfur atom or a phosphorus atom within the above range when an active ingredient value described later is adjusted to 35 to 45%.

  The (meth) acrylic acid polymer aqueous solution of the present invention preferably has a viscosity (25 ° C.) of 400 to 1000 mPa · s when the solid content (nonvolatile content) concentration is adjusted to 35 to 70%. By setting to the above range, the storage stability such as the color tone of the aqueous polymer solution is improved, and the operability on the slurry production facility is improved when used as a pigment dispersant, for example. The viscosity of the (meth) acrylic acid polymer aqueous solution can be easily adjusted by the initiator type and amount used, the type of neutralizer, the amount used, the degree of neutralization, and the like. More preferably, it is 500-900, Most preferably, it is 600-800.

  The (meth) acrylic acid polymer aqueous solution of the present invention preferably has a pH of 3.5 to 9.0 when the solid content (nonvolatile content) concentration is adjusted to 35 to 70%. By setting to the above range, the storage stability such as the color tone of the aqueous polymer solution is improved, and when used as, for example, a pigment dispersant, it is possible to exhibit good dispersibility. The pH of the (meth) acrylic acid polymer aqueous solution can be easily adjusted by the initiator type and amount used, the type of neutralizer, the amount used, the degree of neutralization, and the like. More preferably, it is 4.0-8.5, Most preferably, it is 4.5-8.0.

  The (meth) acrylic acid polymer aqueous solution of the present invention is characterized by being less colored. For example, APHA is preferably 200 or less, and more preferably 180 or less. According to the production method of the present invention, it is possible to suppress the coloring of the aqueous polymer solution to a low level (making the color tone good). When there is little coloring, it can use preferably for a dispersing agent use or detergent builder use, for example.

[(Meth) acrylic acid polymer composition]
The aqueous solution of the (meth) acrylic acid polymer of the present invention can be used after being dried or substituted / diluted with another solvent (referred to as a (meth) acrylic acid polymer composition). The (meth) acrylic acid polymer composition of the present invention includes those obtained by re-dissolving the (meth) acrylic acid polymer aqueous solution of the present invention in water after drying or adding other optional components after drying. .

[Use of (meth) acrylic acid polymer (aqueous solution, composition)]
The (meth) acrylic acid polymer of the present invention, (meth) acrylic acid polymer aqueous solution, (meth) acrylic acid polymer composition (hereinafter also referred to as the polymer of the present invention) are water treatment agents, It can be used as a fiber treatment agent, a dispersant, a detergent builder (or detergent composition) 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 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 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 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 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 polymer of the present invention and at least one selected from the group consisting of a dye, a peroxide and a surfactant is, for example, to improve the whiteness, color unevenness, and dyeing tempering degree 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. In the case of applying to the bleaching step, it is preferable to blend the polymer composition 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.

<Pigment dispersant>
The polymer of the present invention (polymer, polymer aqueous solution, polymer composition) can be used as a pigment dispersant.
Although the polymer of the present invention can be used alone as a pigment dispersant, the pigment dispersant of the present invention includes, as necessary, a solvent such as water and other compounding agents such as condensed phosphoric acid and The salt, phosphonic acid and its salt, and polyvinyl alcohol may be used.

The content of the polymer of the present invention in the pigment dispersant is preferably 0.5 to 10% by weight with respect to the entire pigment dispersant. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effect.
According to the present invention, it is possible to provide a paper slurry having a low viscosity and a viscosity stability with time and having a high concentration. As a result, coating defects are suppressed when coating with the slurry, good base paper coverage, printing gloss, blister resistance, uniform printing surface feeling, and the inherent whiteness and poorness of the pigment are provided. It becomes possible to provide a coated paper for printing having significant points of transparency and ink acceptability.

  The pigment used in the present invention is not particularly limited, and examples thereof include kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, satin white, talc, aluminum hydroxide, and plastic pigment.

  In the present invention, as a method for adjusting the pigment, conventionally known methods can be referred to or combined as appropriate, and examples thereof include a method in which primary dispersion is performed and wet pulverization is performed. This method is preferable in that a high-concentration pigment slurry having a low viscosity and excellent dispersion stability can be obtained. Of course, the method for adjusting the pigment according to the present invention is not limited to this wet pulverization method, and it is not limited at all to adopt an adjustment method without applying the wet pulverization treatment. In the method for preparing the pigment, the primary dispersion method is not particularly limited, but it is preferable to mix with a mixer, for example, a high-speed disper, a homomixer, a ball mill, a coreless mixer, a stirring disper, etc. It is preferable to use a high one.

  In the wet pulverization treatment, the polymer of the present invention may be charged into a pulverizer and pulverized. In such a case, the polymer also serves as a grinding aid.

  The average particle size of the pigment contained in the slurry is preferably 1.5 μm or less, more preferably 1.0 μm or less. The average particle size referred to here is a particle size measured by a laser particle size distribution meter or a particle size distribution meter having an X-ray detector as used in the examples described later. The desired particle size is preferably 85% or more, more preferably 90% or more.

  When the pigment dispersant is used as a pigment dispersant, the amount of the pigment dispersant used is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polymer of the present invention. When the amount of the 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.

  The pigment slurry in the present invention preferably has a solid content concentration of 60% by mass or more, more preferably 70% by mass or more, and further preferably 75% by mass or more.

The viscosity of the pigment slurry is not particularly limited, but varies greatly depending on the slurry concentration. Therefore, immediately after adjusting to 75% by mass, it is preferably 1000 mPa · s or less, more preferably 800 mPa · s or less.
The pigment slurry viscosity is measured using a B-type viscometer. The value measured at 4, 60 rpm for 5 minutes.

<Detergent composition>
The polymer of the present invention can also be added to a detergent composition.
The content of the polymer of the present invention in the detergent composition is not particularly limited. However, from the viewpoint that excellent builder performance can be exhibited, the content of the polymer of the present invention is preferably 0.1 to 15% by mass, more preferably 0, based on the total amount of the detergent composition. 0.3 to 10% by mass, and more preferably 0.5 to 5% by 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 glycosides, fatty acid glycerin monoesters. Alkylamine oxide and the like are preferable. 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 contain other detergent builders in addition to the polymer 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 chelate builders such as acid salts, fumarate salts and zeolites, and carboxyl derivatives of polysaccharides such as carboxymethyl cellulose. 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.
Further, the change (difference) in kaolin turbidity when the polymer of the present invention is added to a liquid detergent composition as a detergent builder is preferably 500 mg / L or less, more preferably 400 mg. / L or less, more preferably 300 mg / L or less, particularly preferably 200 mg / L or less, and most preferably 100 mg / L or less. As the kaolin turbidity value, a value measured by the following method is adopted.

<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.
Even when the detergent composition is used in an area of hard water (for example, 100 mg / L or more) having a high concentration of calcium ions and magnesium ions, salt precipitation is small and has an excellent cleaning effect. This effect is particularly pronounced when the detergent composition contains an anionic surfactant such as LAS.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.
Further, the weight average molecular weight, number average molecular weight, quantification of unreacted monomer, polymer composition, solid content of polymer aqueous solution, and the like of the polymer of the present invention were measured according to the following methods.

<Polymer aqueous solution, method for measuring solid content of polymer composition>
The polymer composition (polymer composition 1.0 g + water 3.0 g) was left to dry for 2 hours in an oven heated to 110 ° C. in a nitrogen atmosphere. From the weight change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Measurement of active ingredients>
The effective component value was measured and calculated with an automatic titrator COM-1500 manufactured by Hiranuma Sangyo Co., Ltd. as the carboxyl group concentration of the polymer obtained by polymerization. First, the carboxylic acid in the polymer is completely neutralized with 1N NaOH aqueous solution, then a titration curve is prepared with 1N HCl aqueous solution, and the difference between the second inflection point and the first inflection point of the curve (the amount of 1N HCl solution) ) Was calculated as follows.
Effective component value (%) = 9.4 × (1N HCl amount at the second inflection point (volume (ml)) − 1N HCl amount at the first inflection point (volume (ml))) × HCl titer / Analyte amount (mass (g)).
The amount of analyte represents the mass of the analyzed (meth) acrylic acid polymer aqueous solution.

<Measurement conditions of weight average molecular weight and number average molecular weight (GPC)>
Apparatus: L-7000 series manufactured by Hitachi, Ltd. Detector: HITACHI RI Detector L-2490
Column: Tosoh TSK-GEL G3000PWXL
Column temperature: 40 ° C
Flow rate: 0.5 mL / min
Calibration curve: POLY SODIUM ACRYLATE STANDARD made by Soka Science Co., Ltd.
Eluent: A solution obtained by diluting a mixture of sodium dihydrogen phosphate 12 hydrate / disodium hydrogen phosphate dihydrate (34.5 g / 46.2 g) to 5000 g with pure water.

<Measurement of polymer aqueous solution, monomers in polymer composition>
The monomer was measured using liquid chromatography under the following conditions.
Measuring device: L-7000 series detector manufactured by Hitachi, Ltd .: UV detector L-7400 manufactured by Hitachi, Ltd.
Column: SHODEX RSpak DE-413 manufactured by Showa Denko Co., Ltd.
Temperature: 40.0 ° C
Eluent: 0.1% phosphoric acid aqueous solution Flow rate: 1.0 ml / min.

<Anion concentration analysis (ion chromatography analysis)>
In the anion concentration analysis, ion chromatography analysis was performed under the following conditions.
Apparatus: manufactured by Metrohm (762 Interface)
Detector: 732 IC Detector manufactured by Metrohm
Ion analysis method: Suppressor method Column: Shodex IC SI-90 4E
Guard column: Shodex SI-90 G
Column temperature: 40 ° C
Eluent: NaHCO ₃ water (2 g diluted to 2000 g with water)
Flow rate: 1.0 mL / min.
Analysis of the aqueous polymer solution obtained in the following examples revealed sulfate ions derived from sodium persulfate and hypophosphite ions derived from sodium hypophosphite.

<Hue (APHA)>
It was measured by a colorimetric method with a standard sample by the APHA method.

<Evaluation example>
Put 200 parts by weight of commercially available Maruo Calcium Co., Heavy Calcium Carbonate Powder into a 500 ml SUS container, and attach a stirring seal to the widest mouth at the top of the lid of a glass four-neck separable flask wrapped with a heat insulating material. A SUS stirring blade equipped with a three-stage pin is attached to the container, the remaining mouth is covered with a silicone rubber stopper, and the SUS container and the upper part of the glass lid are fixed at two locations with fixing stoppers. The SUS stirring blade and a powerful stirring motor were connected, and the entire container was firmly fixed to the support so as not to loosen during the pulverization.
Subsequently, one of the silicone rubber stoppers of the four-neck separable flask is opened, a funnel is inserted, and while stirring with a stirring motor at a low speed of about 200 to 300 rpm, the active ingredient value becomes 10%. A mixture prepared by mixing 8 parts by weight of an aqueous polymer solution (diluted or concentrated with water, etc.) and 46 parts by weight of pure water and 500 parts by weight of 2 mm ceramic beads were added little by little. After all of them were put in, a silicone rubber stopper was attached, and the number of revolutions was increased to 1000 rpm at once. After confirming the state of the beads, the number of revolutions was further increased to 1500 rpm. After 40 minutes from the start of pulverization, 4 parts by mass of a 10% aqueous polymer solution was added, and further 2 parts by mass after 70 and 90 minutes. In this state, pulverization was continued until the particle size of 2 μm or less reached 90% or more. Finally, the amount of polymer added was 0.80% by mass with respect to heavy calcium carbonate. After grinding, the contents were separated from the ceramic and collected.
The particle size was analyzed with a laser particle size distribution analyzer LA-910 manufactured by Horiba.
The viscosity of the slurry was measured using a B-type viscometer, and the rotor The viscosity after 4, 60 rpm and 5 minutes was measured (slurry viscosity immediately after) and compared. The recovered slurry was stored in an environment at 25 ° C. until immediately before the measurement.

  After the sample was stored at 25 ° C. for 1 week, the rotor no. The viscosity after 4, 60 rpm and 5 minutes was measured (slurry viscosity after 1 week).

  The slurry is filled in a polypropylene container (screw cap) having an inner diameter of 16 mm and a height of 11 mm, and left to dry in an oven heated to 110 ° C. for 2 hours. Measurement was performed by reflection measurement using SE-2000, and b values were compared.

<Example 1>
345 parts by mass of ion-exchanged water was placed in an apparatus having a 2.5 L SUS batch polymerization kettle, a thermometer, a stirrer (paddle blade), and a reflux condenser, and heated to the boiling point and refluxed. Next, 900 parts by mass of an 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”) is 180 minutes, and 49 parts by mass of a 15% by mass sodium persulfate aqueous solution (hereinafter also referred to as “15% NaPS”). 185 minutes, 20 parts by mass of 35% aqueous hydrogen peroxide (hereinafter also referred to as “35% H ₂ O ₂ ”) for 180 minutes, 45% by mass of sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) 17 parts by mass for 20 minutes, and then 70 parts by mass for 160 minutes at two stages of supply rates, respectively, were added dropwise through separate supply paths. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP.
Then, after maintaining heating under reflux conditions for 30 minutes, heating was stopped, 185 parts by mass of water was added, and 750 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 90%) was supplied through the supply route. The polymer was neutralized by dripping into the polymerization kettle. As described above, a sodium polyacrylate aqueous solution (1) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (1)) had a solid content value of 42.5% and an active ingredient value of 40.7%. The polymer aqueous solution (1) had a weight average molecular weight (Mw) of 5200 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.30. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the aqueous polymer solution (1) (mainly sulfate ions and hypophosphite ions were detected) was 4300 ppm. The solid hue (APHA) of the aqueous polymer solution (1) was 15.
The polymerization formulation and analysis results are shown in Table 1. In Table 1, the density | concentration of the inorganic anion containing a sulfur atom or a phosphorus atom was described as ion concentration total.
When the slurry viscosity of the heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity after 1 hour of pulverization was 1250 mPa · s, and the slurry viscosity after 1 week was 4180 mPa · s. The color of the dried slurry was 2.68 in b value.

<Comparative Example 1>
A sodium polyacrylate aqueous solution (2) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1 (no 35% hydrogen peroxide aqueous solution was added dropwise). The obtained aqueous solution (referred to as polymer aqueous solution (2)) had a solid content value of 42.9% and an active ingredient value of 41.0%. The polymer aqueous solution (2) had a weight average molecular weight (Mw) of 5700 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.18. The solid hue (APHA) of the aqueous polymer solution (2) was 50.
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 1260 mPa · s, and the slurry viscosity after one week was 4230 mPa · s. The color of the dried slurry was 2.94 in b value.

<Example 2>
345 parts by mass of ion-exchanged water was placed in an apparatus having a 2.5 L SUS batch polymerization kettle, a thermometer, a stirrer (paddle blade), and a reflux condenser, and heated to the boiling point and refluxed. Next, 900 parts by mass of an 80% by mass acrylic acid aqueous solution for 180 minutes, 49 parts by mass of a 15% by mass aqueous sodium persulfate solution for 185 minutes, 20 parts by mass of a 35% aqueous hydrogen peroxide solution for 180 minutes, 45% by mass hypophosphorous acid A sodium acid aqueous solution was dropped at 16 parts by mass for 20 minutes, followed by 58 parts by mass at 160 minutes and at two stages of supply rates through separate supply paths. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP.
Then, after maintaining heating under reflux conditions for 30 minutes, heating was stopped, 185 parts by mass of water was added, and 583 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate 70%) was supplied through the supply route. Then, 153 parts by mass of monoethanolamine (hereinafter also referred to as “MEA”) (AA neutralization rate of 25%) is dropped into the polymerization kettle through another supply path, and the polymer is dropped. Neutralized. As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (3) was obtained. The obtained polymer aqueous solution (3) had a solid content value of 47.8% and an active ingredient value of 41.0%. The polymer aqueous solution (3) had a weight average molecular weight (Mw) of 6700 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.56. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the aqueous polymer solution (3) was 4900 ppm. Further, APHA in the form of the polymer aqueous solution (3) was 20.
When the slurry viscosity of heavy calcium carbonate was evaluated by the above-mentioned method, the slurry viscosity 1 hour after the completion of pulverization was 1560 mPa · s, and the slurry viscosity after 1 week was 4280 mPa · s. The color of the dried slurry was 3.05 in b value.

<Comparative example 2>
In the same manner as in Example 2, except that the polymerization conditions are changed to those shown in Table 1 (no 35% aqueous hydrogen peroxide solution is added dropwise), an aqueous solution of sodium polyacrylate / monoethanolamine salt (4 ) The obtained polymer aqueous solution (4) had a solid content value of 48.2% and an active ingredient value of 41.3%. The polymer aqueous solution (4) had a weight average molecular weight (Mw) of 7000 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.43. The solid hue (APHA) of the aqueous polymer solution (4) was 60.
As in Example 2, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 1600 mPa · s, and the slurry viscosity after 1 week was 4320 mPa · s. The color of the dried slurry was 3.45 in b value.

<Example 3>
350 parts by mass of ion-exchanged water was placed in a 2.5 L SUS batch polymerization kettle, a thermometer, a stirrer (paddle blade), and a reflux condenser, and the mixture was heated to the boiling point and refluxed. Next, 900 parts by weight of an 80% by weight aqueous acrylic acid solution was continued for 180 minutes, 49 parts by weight of a 15% by weight aqueous sodium persulfate aqueous solution for 185 minutes, 17 parts by weight of a 45% by weight aqueous sodium hypophosphite aqueous solution and 20 minutes further 70 parts by mass were added dropwise through separate supply channels for 160 minutes and at two supply rates. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP.
Next, 2.6 parts by mass of a 35% aqueous hydrogen peroxide solution was added dropwise over 20 minutes, and heating was further maintained under reflux conditions for 10 minutes. After adding 229 parts by mass of water, the heating was stopped, and 417 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 50%) was dropped into the polymerization kettle through the supply route, followed by monoethanolamine. 281 parts by mass (AA neutralization rate: 46%) was added dropwise to the polymerization kettle through another supply path to neutralize the polymer. As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (5) was obtained. The obtained polymer aqueous solution (5) had a solid content value of 51.6% and an active ingredient value of 40.6%. The polymer aqueous solution (5) had a weight average molecular weight (Mw) of 5,500 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.20. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the aqueous polymer solution (5) was 4400 ppm. Further, APHA in the form of the polymer aqueous solution (5) was 20.
When the slurry viscosity of heavy calcium carbonate was evaluated by the above-mentioned method, the slurry viscosity 1 hour after the completion of pulverization was 830 mPa · s, and the slurry viscosity after 1 week was 2770 mPa · s. The color of the dried slurry was 4.11 in b value.

<Comparative Example 3>
In the same manner as in Example 3, except that the polymerization conditions were changed to the method described in Table 1 (no 35% aqueous hydrogen peroxide solution was added dropwise), an aqueous solution of sodium polyacrylate / monoethanolamine salt (6 ) The obtained polymer aqueous solution (6) had a solid content value of 51.7% and an active ingredient value of 40.4%. The polymer aqueous solution (6) had a weight average molecular weight (Mw) of 5600 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.18. Further, APHA in the form of the polymer aqueous solution (5) was 70.
As in Example 3, when the slurry viscosity of heavy calcium carbonate was evaluated by the method described above, the slurry viscosity immediately after pulverization was 960 mPa · s, and the slurry viscosity after one week was 3020 mPa · s. The color of the dried slurry was 4.75 in b value.

  Table 1 summarizes the polymerization formulation and measurement results of the polymer (composition), and Table 2 summarizes the evaluation results.

From the results shown in Table 2, the polymer of the present invention has a good dispersibility and a good color tone as compared with the conventional polymer, and further the calcium carbonate dispersion slurry when used in the calcium carbonate dispersion slurry. It was revealed that the color tone can be suppressed satisfactorily (low coloration).

Claims (3)

(I) a step of polymerizing a (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt);
(Ii) adding 0.05 to 1.5 g of hydrogen peroxide to the reaction liquid with respect to 1 mol of the monomer used during and / or after the polymerization of the (meth) acrylic acid monomer; ,
A process for producing a (meth) acrylic acid polymer. (I) a step of polymerizing a (meth) acrylic acid monomer in the presence of hypophosphorous acid (salt);
(Ii) adding 0.05 to 1.5 g of hydrogen peroxide to the reaction liquid with respect to 1 mol of the monomer used during and / or after the polymerization of the (meth) acrylic acid monomer; ,
A (meth) acrylic acid polymer produced by a method comprising: A pigment dispersant comprising the (meth) acrylic acid polymer according to claim 2.