JP2011256225A - Poly(meth)acrylic acid system polymer aqueous solution and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a poly(meth)acrylic system polymer aqueous solution which has an excellent color tone, is excellent in the dispersibility or the like of an inorganic substance, and exhibits sufficient temporal dispersibility.SOLUTION: This poly(meth)acrylic acid system polymer aqueous solution contains a poly(meth)acrylic acid system polymer. The poly(meth)acrylic acid system polymer is polymerized under the existence of an alcohol whose carbon number is 1 to 6, at least a part of a carboxyl group of the poly(meth)acrylic acid system polymer is neutralized by organic amine, a molar ratio between structure derived from a (meth)acrylic acid (salt) contained in the aqueous solution and structure derived from the organic amine (salt) is 100:10 to 100:75, and a concentration of an inorganic anion containing a sulfur atom or a phosphor atom which is contained in the aqueous solution is 5,000 to 40,000 ppm with respect to the aqueous solution.

Description

The present invention relates to an aqueous poly (meth) acrylic acid polymer solution and a method for producing the same. More specifically, the present invention relates to a poly (meth) acrylic acid polymer aqueous solution which is excellent in pigment dispersion and the like.

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, higher performance polymers are required.

  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, with the recent advancement and refinement of pigment coating machines, for example, there has been an increasing demand for polymers that exhibit more stringent dispersibility of pigments, in particular dispersibility with little change over time. Furthermore, for example, when used for a dispersant for a paper processing pigment slurry, a polymer composition with little coloring is required so as not to affect the whiteness of paper in addition to the above performance.

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

The present invention is to provide a polymer (aqueous solution) having excellent dispersibility of inorganic materials, exhibiting sufficient dispersibility over time, and having an excellent color tone, and a method for easily producing the polymer (aqueous solution). Objective.

The present inventors have intensively studied to solve the above problems. As a result, it has been found that a specific aqueous solution containing a polyacrylic acid polymer (partially) neutralized with an organic amine exhibits good dispersibility of an inorganic substance and stable dispersibility over time. Furthermore, when the polymer was produced in the presence of an alcohol and a specific reducing compound, it was found that the color tone was improved and the present invention was completed.
That is, the poly (meth) acrylic acid polymer aqueous solution according to the present invention is an aqueous solution containing a poly (meth) acrylic acid polymer, and the poly (meth) acrylic acid polymer has 1 to 1 carbon atoms. 6 (polymer) polymerized in the presence of alcohol, and at least part of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine, and is contained in the aqueous solution. The molar ratio of the structure derived from the acid (salt) and the structure derived from the organic amine (salt) is 100: 10 to 100: 75, and the inorganic anion containing a sulfur atom or a phosphorus atom is contained in the aqueous solution. The concentration is 5000 to 40000 ppm with respect to the aqueous solution,
It is the aqueous solution characterized by being.
Another aspect of the present invention provides a method for producing an aqueous poly (meth) acrylic acid polymer solution. That is, the method for producing an aqueous poly (meth) acrylic acid polymer solution of the present invention comprises polymerizing a (meth) acrylic acid monomer in the presence of an alcohol having 1 to 6 carbon atoms. This is a method for producing a (meth) acrylic acid polymer aqueous solution.

The aqueous poly (meth) acrylic acid polymer solution of the present invention has an excellent color tone, and can exhibit excellent dispersibility of inorganic fine particles such as mud stains and inorganic pigments, and dispersibility over time. Therefore, when used as a detergent builder or pigment dispersant, excellent detergency and stable dispersibility of the pigment over time can be obtained.
According to the method for producing an aqueous polymer solution of the present invention, it has an excellent color tone, has excellent dispersibility of inorganic fine particles such as mud stains and inorganic pigments, and can further exhibit dispersive power over time. A polymer aqueous solution can be produced efficiently.

Hereinafter, the present invention will be described in detail.

[Poly (meth) acrylic acid polymer]
The poly (meth) acrylic acid polymer aqueous solution of the present invention contains a poly (meth) acrylic acid polymer (also referred to as the poly (meth) acrylic acid polymer of the present invention).
In the present invention, the poly (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 this structure, R represents a hydrogen atom or a methyl group, M represents a hydrogen atom, an alkali metal atom such as Li, Na, or K, an alkaline earth metal atom such as Ca or Mg, an ammonium salt, or an organic amine salt. To express.
In the present invention, (meth) acrylic acid (salt) refers to acrylic acid, acrylate, methacrylic acid, and methacrylate, and examples of the salt include alkali metal salts such as Li, Na, and K, Ca, Mg An alkaline earth metal salt such as ammonium salt or organic amine salt.

The carboxyl group possessed by the poly (meth) acrylic acid polymer is characterized in that at least a part thereof is neutralized with an organic amine salt, and all of the carboxyl groups possessed by the poly (meth) acrylic acid polymer Even if the structure is neutralized (neutralized type), a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized, and the rest is an acid type structure. (Partial neutralization type) is acceptable.
Carboxyl groups of the poly (meth) acrylic acid polymer other than acid type carboxyl groups / carboxyl groups neutralized with organic amines (organic amine salt type carboxyl groups) / carboxyl other than organic amine salt type carboxyl groups The proportion of the salt of the group is not particularly limited, but is included in the poly (meth) acrylic acid polymer aqueous solution of the present invention (in other words, the total amount of the compound contained in the poly (meth) acrylic acid polymer aqueous solution of the present invention). It is important that the molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) is 100: 10 to 100: 75. Preferably, it is more preferably 100: 15 to 100: 70, and particularly preferably 100: 20 to 100: 65.

  In the structure derived from the organic amine (salt), the organic amine (salt) may be any of primary amine, secondary amine, tertiary amine, quaternary amine, and salts thereof, and one of them may be used alone. It may be used, and two or more kinds may be used in combination. For example, alkanolamines such as monoethanolamine, monopropanolamine, diethanolamine and triethanolamine; alkylamines such as methylamine, ethylamine, butylamine, dimethylamine and diethylamine; alkylamines such as cyclohexylamine; cyclohexylamine, pyrrolidine, piperidine, Examples include cyclic amines such as pyridine, pyrazine, pyrrole and morpholine; and polyalkyleneamines such as ethylenediamine and diethylenetriamine. Among these, the poly (meth) acrylic acid polymer aqueous solution is an alkanol from the viewpoint that the pigment dispersion performance with time of the polymer aqueous solution is remarkably improved, easy to handle, and relatively inexpensive. It preferably contains a structure derived from an amine (salt).

The structure derived from the organic amine (salt) is a structure formed by reacting an added organic amine (salt) in the process of producing the poly (meth) acrylic acid polymer aqueous solution of the present invention. Alternatively, it represents an organic amine (salt) that remains unreacted. The structure formed by the reaction of the added organic amine (salt) is, for example, by (i) adding an organic amine to an aqueous solution containing an acid type and / or partially neutralized polyacrylic acid polymer. The structure contained in the formed carboxyl group salt neutralized with organic amine, or (ii) the organic amine salt in which a monomer such as (meth) acrylic acid is neutralized with organic amine in advance is polymerized. The structure formed by is illustrated.
Since the pigment dispersion performance over time tends to be improved, the poly (meth) acrylic acid polymer aqueous solution of the present invention preferably reduces inorganic salts as much as possible. Therefore, the structure derived from organic amine (salt) is The carboxyl group is preferably neutralized with an organic amine. Therefore, the ratio of the carboxyl group neutralized with an organic amine (organic amine salt-type carboxyl group) is 10 to 75 mol% with respect to 100 mol% of the carboxyl group of the poly (meth) acrylic acid polymer. It is preferably 15 to 70 mol%, more preferably 20 to 65 mol%.

The poly (meth) acrylic acid polymer of the present invention is preferably produced by polymerization in the presence of an alcohol having 1 to 6 carbon atoms because the color tone is good (coloring is small). . By the way, the poly (meth) acrylic acid polymer is preferably polymerized in a solvent containing water because of its good solubility, but it has a good color tone due to its good compatibility with water. It is preferable to use an alcohol having 1 to 6 carbon atoms.
Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutyl alcohol, t-butyl alcohol, isopentyl alcohol, and isohexyl alcohol. Of these, isopropyl alcohol and isobutyl alcohol are preferred because of excellent color tone improvement effect.

When the poly (meth) acrylic acid polymer of the present invention is produced by polymerization in the presence of an alcohol having 1 to 6 carbon atoms, the structure is derived from an alcohol having 1 to 6 carbon atoms due to chain transfer during the polymerization. May be included. For example, a structure derived from isopropyl alcohol or isobutyl alcohol is preferable because the dispersibility of the pigment tends to be improved. The structure derived from isopropyl alcohol or isobutyl alcohol can be confirmed by, for example, ¹ HNMR.

  The amount of the C1-C6 alcohol used when producing the poly (meth) acrylic acid polymer of the present invention is 10 to 70% by mass with respect to 100% by mass of the reaction liquid after completion of the polymerization. It is preferable that the content is 20 to 60% by mass.

Since the poly (meth) acrylic acid polymer of the present invention has a good color tone (low coloration), it is produced by polymerizing in the presence of an alcohol having 1 to 6 carbon atoms, in addition to a specific reduction. It is preferable to produce in the presence of a functional compound. In particular, when a neutralization step is provided after the polymerization, in order to efficiently carry out the neutralization reaction, it is necessary to carry out after removing (or removing) the alcohol having 1 to 6 carbon atoms. The color tone tends to decrease. Therefore, it is particularly preferable that the specific reducing compound is present during or after the neutralization step.
In the present invention, as the specific reducing compound, since the color tone is good, hypophosphorous acid (salt) such as hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, etc., sodium bisulfite Bisulfites such as potassium hydrogen sulfite and sodium metabisulfite are preferred.

  The amount of the specific reducing compound (total of hypophosphorous acid (salt) and bisulfite) used when producing the poly (meth) acrylic acid polymer of the present invention is as described below. . However, as described above, since the pigment dispersion performance with time tends to be improved, it is preferable that the aqueous poly (meth) acrylic acid polymer solution of the present invention reduces inorganic salts and the like as much as possible. As a result, in order to combine dispersibility with time and color tone, the concentration of inorganic anions containing sulfur atoms or phosphorus atoms contained in the aqueous solution should be set to 5000 to 40000 ppm with respect to the aqueous solution. Is preferred.

  Production of poly (meth) acrylic acid polymer using hypophosphorous acid (salt) and / or bisulfite, which are the specific reducing compounds present in the neutralization step or after neutralization for the purpose of improving hue. Sometimes used as a chain transfer agent. In that case, the amount of hypophosphorous acid (salt) and / or bisulfite used as the chain transfer agent in the production of the poly (meth) acrylic acid polymer, and present during or after the neutralization step The total amount of hypophosphorous acid (salt) and / or bisulfite used as the reducing compound is adjusted, and the sulfur atom or phosphorus atom contained in the poly (meth) acrylic acid polymer aqueous solution is adjusted. It is preferable that the density | concentration of the inorganic anion to contain is set to 5000-40000 ppm with respect to the said aqueous solution.

The poly (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) The structure derived from the monomer may be included.
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.

  The poly (meth) acrylic acid polymer of the present invention has a structure derived from all monomers contained in the poly (meth) acrylic acid polymer of the present invention (that is, a structure derived from (meth) acrylic acid (salt)). And (meth) acrylic acid (salt) -derived structure is preferably contained in an amount of 80% by mass or more in terms of acid type with respect to 100% by mass. If it is 80 mass% or more, the pigment dispersion performance with time of the polymer aqueous solution tends to be improved. Here, acid type conversion means calculating a mass ratio using a salt type monomer as a corresponding acid type monomer. For example, if the structure is derived from sodium (meth) acrylate, (meth) The mass ratio is calculated as a structure derived from acrylic acid. The other monomers are similarly calculated in terms of acid type.

  The structure derived from (meth) acrylic acid (salt) in the poly (meth) acrylic acid polymer of the present invention is preferably a structure derived from acrylic acid (salt).

Specifically, the weight average molecular weight of the poly (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 poly (meth) acrylic-acid type polymer of this invention.
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the poly (meth) acrylic acid polymer of the present invention is preferably 1.1 to 3.0, more preferably. Is 1.5 to 2.8, more preferably 1.8 to 2.6.
If the molecular weight distribution is too small, for example, when a poly (meth) acrylic acid polymer is used as an inorganic dispersant, the slurry viscosity immediately after pulverization when the inorganic material is wet pulverized may increase. Moreover, when too large, there exists a possibility that the viscosity stability with time of a slurry may fall. 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 poly (meth) acrylic-acid type polymer of this invention.

[Poly (meth) acrylic acid polymer aqueous solution]
The polymer aqueous solution of the present invention essentially contains the poly (meth) acrylic acid polymer of the present invention. In addition, unreacted (meth) acrylic acid (salt), other unreacted monomers, unreacted polymerization initiator, polymerization initiator decomposition product, and the like may be included.
The content of unreacted monomers present in the polymer composition (the total content of (meth) acrylic acid (salt) and other monomers) varies depending on the type of monomer used. However, it is preferably less than 1% by mass with respect to 100% by mass of the solid content of the polymer composition. More preferably, it is less than 0.5% and less than 0.1%.

  The poly (meth) acrylic acid polymer aqueous solution referred to in the present invention is not particularly limited, but after producing the poly (meth) acrylic acid polymer in an aqueous solvent described later, purification such as impurity removal. Although it may be manufactured through a process, from the viewpoint of production efficiency, a product obtained by simplifying the purification process as much as possible 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 poly (meth) acrylic acid polymer aqueous solution referred to in this application.

  The poly (meth) acrylic acid-based polymer aqueous solution of the present invention contains a solvent in which water is essential in addition to the poly (meth) acrylic acid-based polymer of the present invention. In that case, the content of the solvent is preferably about 50 to 500% by mass, more preferably about 60 to 400% by mass, and about 80 to 300% by mass with respect to 100% by mass of the poly (meth) acrylic acid polymer. Is preferable, and about 90-200 mass% is the most preferable.

The aqueous poly (meth) acrylic acid polymer solution of the present invention preferably has a step of polymerizing a (meth) acrylic acid monomer in the presence of an alcohol having 1 to 6 carbon atoms as described above (both in step (a)). However, as will be described later, the content of the organic solvent can be reduced as much as possible from the limitation of use of the poly (meth) acrylic acid polymer aqueous solution or from the viewpoint of performance improvement. Preferably, for example, the content of the organic solvent is preferably 10% by mass or less, more preferably 5% by mass or less, and preferably 1% by mass or less with respect to 100% by mass of the poly (meth) acrylic acid polymer aqueous solution. That is, in the present invention, the poly (meth) acrylic acid polymer aqueous solution may contain a solvent other than water.
Therefore, when the poly (meth) acrylic acid polymer aqueous solution of the present invention is produced by the production method including the step (a), it is preferable to include a step of removing an alcohol having 1 to 6 carbon atoms. The removal of the alcohol having 1 to 6 carbon atoms is preferably carried out by a liquid-liquid separation method or a distillation method. In particular, when the aqueous poly (meth) acrylic acid polymer solution of the present invention includes a neutralization step after polymerization, the alcohol having 1 to 6 carbon atoms may be distilled off before or during the neutralization step. preferable. Here, “the alcohol having 1 to 6 carbon atoms is distilled off during the neutralization step” means that an alkali metal hydroxide or carbonate, an alkaline earth metal hydroxide or carbonate, ammonia, an amine In parallel with distilling off alcohols having 1 to 6 carbon atoms while neutralizing with a base such as alkali metal hydroxides and carbonates, alkaline earth metal hydroxides and carbonates, ammonia It shows that after partially neutralizing with a base such as an amine (after performing a part of the neutralization step), the alcohol having 1 to 6 carbon atoms is distilled off.

The aqueous poly (meth) acrylic acid polymer solution of the present invention is characterized in that the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is 5000 to 40000 ppm with respect to the aqueous solution. When the concentration of inorganic anions containing sulfur atoms or phosphorus atoms exceeds 40,000 ppm, the pigment dispersion performance with time of the aqueous polymer solution tends to be lowered. When the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is set to less than 5000 ppm, the remarkable effect of improving color tone tends to be reduced. 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 poly (meth) acrylic acid polymer aqueous solution of the present invention is preferably less colored. For example, the hue (APHA) of the polymer aqueous solution immediately after production is preferably 200 or less, more preferably 180 or less, 160 or less is more preferable. According to the production method of the present invention, it is possible to suppress the coloring of the polymer to be low (better color tone), and to achieve the above hue range. When there is little coloring, it can use preferably for a dispersing agent use or detergent builder use, for example.

  The poly (meth) acrylic acid polymer aqueous solution of the present invention preferably has a viscosity (25 ° C.) of 400 to 1500 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 poly (meth) acrylic acid polymer aqueous solution can be easily adjusted by the initiator type and amount used, the neutralizer type and amount used, the degree of neutralization, and the like. More preferably, it is 500-900, Most preferably, it is 600-800.

  The aqueous poly (meth) acrylic acid polymer solution of the present invention preferably has a pH of 6.5 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 poly (meth) acrylic acid polymer aqueous solution can be easily adjusted by the type of initiator used, the amount used, the type of neutralizer, the amount used, the degree of neutralization, and the like. More preferably, it is 6.8 to 8.5, and particularly preferably 7.0 to 8.0.

[Poly (meth) acrylic acid polymer composition]
The poly (meth) acrylic acid polymer aqueous solution of the present invention can be used after drying or substitution / dilution with another solvent (referred to as a poly (meth) acrylic acid polymer composition). The poly (meth) acrylic acid polymer composition of the present invention includes the polyacrylic acid polymer aqueous solution of the present invention that has been dried and then redissolved in water, or other optional components added after drying.

[Production method of poly (meth) acrylic acid polymer (aqueous solution)]
The poly (meth) acrylic acid polymer of the present invention is preferably produced by polymerizing (meth) acrylic acid (salt) as an essential component. The poly (meth) acrylic acid polymer of the present invention may be produced by copolymerizing the above-mentioned other monomers in addition to (meth) acrylic acid (salt). (Meth) acrylic acid (100% by weight) of (meth) acrylic acid (referring to the total of (meth) acrylic acid (salt) and other monomers) used in the production of the poly (meth) acrylic acid polymer of the present invention. The ratio of the salt) is preferably 90% by mass or more in terms of acid type. If it is 90 mass% or more, the pigment dispersion performance with time of the resulting aqueous polymer solution tends to be improved. Here, as described above, conversion to acid type means calculating a mass ratio using a salt type monomer as a corresponding acid type monomer. For example, if sodium (meth) acrylate is used, ) Calculate mass percentage as acrylic acid. The other monomers are similarly calculated in terms of acid type.
As a manufacturing method of this invention, it is preferable to use acrylic acid (salt) as (meth) acrylic acid (salt).

The poly (meth) acrylic acid polymer (aqueous solution) of the present invention is a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an organic amine (or It is preferable to manufacture by including an organic amine in an aqueous solution containing an acid type and / or a partially neutralized poly (meth) acrylic acid polymer. According to the production method, the color tone and the like of the resulting polymer aqueous solution become particularly good, and when used as a pigment dispersant, for example, it tends to exhibit particularly good dispersibility. As the organic amine used in the neutralizing step (or the adding step), the above-mentioned ones are used. Preferably, the alkanol is remarkably improved over time in the pigment dispersion performance of the aqueous polymer solution. It is an amine.
When the poly (meth) acrylic acid polymer (aqueous solution) of the present invention is produced including a step of neutralizing with the organic amine, other neutralizing agents may be used in addition to the organic amine. In this case, however, in order to reduce coloring during the neutralization reaction, first, an aqueous solution containing an acid-type and / or partially-neutralized poly (meth) acrylic acid polymer is added with another neutralizing agent. It is preferable to perform a step of neutralizing and then performing a step of neutralizing an aqueous solution containing an acid-type and / or partially neutralized polyacrylic acid polymer with an organic amine, because the color tone becomes favorable. The reverse is also possible. As long as the molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) contained in the poly (meth) acrylic acid polymer aqueous solution falls within the above range, Excess organic amine (salt) may be added beyond the sum. By setting the molar ratio of the structure derived from the organic amine (salt) contained in the poly (meth) acrylic acid-based polymer aqueous solution to the above range, the poly (meth) acrylic acid-based polymer aqueous solution is changed over time. Dispersion force is remarkably expressed.
Examples of other neutralizing agents for organic amines include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate, potassium carbonate and sodium hydrogen carbonate, and ammonia.
However, for the purpose of simplifying the production process, an aqueous poly (meth) acrylic acid polymer solution may be produced by carrying out polymerization with an organic amine salt of (meth) acrylic acid as an essential component. In this case, coloring increases, and it may be difficult to use as a detergent additive or a pigment dispersant.

The poly (meth) acrylic acid polymer of the present invention is a step of neutralizing an aqueous solution containing an acid type and / or a partially neutralized poly (meth) acrylic acid polymer with an organic amine (or an acid type). And / or a step of adding an organic amine to an aqueous solution containing a partially neutralized poly (meth) acrylic acid polymer), and these are referred to as step A). Producing by including a step (referred to as Step B) of producing an aqueous solution containing an acid-type and / or partially neutralized poly (meth) acrylic acid-based polymer by polymerizing acrylic acid (salt) as an essential component. Is preferred. In this case, the neutralization rate (total acid groups (neutralized and non-neutralized) of the acid-type and / or partially neutralized poly (meth) acrylic acid-based polymer (after Step B) produced in Step B The ratio of the acid group neutralized with respect to is preferably from 0 to 90%, more preferably from 0 to 35%, since the color tone tends to improve over time in the pigment dispersion performance and aqueous solution. 10% is particularly preferred.
The poly (meth) acrylic acid polymer of the present invention is a step of partially neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with another neutralizing agent (step) C) is preferably included. The step C is preferably performed after the step B. The neutralization rate of the partially neutralized poly (meth) acrylic acid polymer after Step C is preferably from 5 to 90%, more preferably from 10 to 85% because the color tone tends to improve. 15 to 80% is particularly preferable.

  As described above, the method for producing a poly (meth) acrylic acid polymer (aqueous solution) according to the present invention is produced by polymerizing a poly (meth) acrylic acid monomer in the presence of an alcohol having 1 to 6 carbon atoms. In this case, it is preferable to include a step of removing alcohol having 1 to 6 carbon atoms. Preferably, as described above, when the production method of the present invention includes a neutralization step, before or during the neutralization step. It is preferable to distill off the alcohol having 1 to 6 carbon atoms. If not distilled off, separation of the liquid layer usually occurs during the neutralization step, so the upper layer (the alcohol layer having 1 to 6 carbon atoms) will be removed by liquid-liquid separation. Since the process becomes complicated, the production efficiency may be reduced.

(Polymerization initiator)
The poly (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). be able to.
Known polymerization initiators can be used such as persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; hydrogen peroxide; dimethyl 2,2′-azobis (2-methylpropio Nate), 2,2′-azobis (2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanoparerenic acid, azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2, Preferred are azo compounds such as 4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide and cumene hydroperoxide. These polymerization initiators may be used alone or in the form of a mixture of two or more. Since the molecular weight distribution of the polymer tends to be small, it is preferable to use only one kind.
The amount of the polymerization initiator used 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 greatly affect the dispersibility of the pigment in the aqueous poly (meth) acrylic acid polymer solution obtained. 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 mass or more of the required predetermined amount, and particularly preferably 80% by mass. %, 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 the monomer dropping, and within 5 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)
The poly (meth) acrylic acid polymer of the present invention can also use a chain transfer agent in addition to the polymerization initiator. 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-mercaptopropion, 3-mercaptopropion, 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; Acid, phosphite, hypophosphorous acid, hypophosphite, and hydrates thereof; sulfurous acid, hydrogen sulfite, dithionic acid, metabisulfite, and salts thereof (sodium hydrogen sulfite, hydrogen sulfite) Potassium, sodium dithionite, bis Potassium propionic acid, sodium metabisulfite, bisulfite) or the like, such as potassium metabisulfite, 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.
The addition amount of the chain transfer agent is 1 to 20 g, more preferably 2 to 15 g, with respect to 1 mol of all monomer components, unless otherwise specified. If it is less than 1 g, the molecular weight may not be controlled. Conversely, if it exceeds 20 g, the chain transfer agent may remain or the polymer content may decrease.

Among the chain transfer agents, it is preferable to use hypophosphorous acid (salt) and / or bisulfite since the dispersibility of the pigment in the resulting aqueous poly (meth) acrylic acid polymer solution is improved. . However, since the dispersive power with time of the pigment is improved, hypophosphorous acid (salt) and bisulfite (total when combined) are used in an amount of 1 mol of all monomers. The amount is preferably 5.0 g or less, more preferably 4.5 g or less, particularly preferably 4.0 g or less, and the lower limit of the amount used is 1. 0 g or more is preferable, and 1.5 g or more is more preferable.
If the amount of hypophosphorous acid (salt) and / or bisulfite used exceeds the above upper limit with respect to 1 mol of all monomers, hypophosphite and / or bisulfite that does not contribute to chain transfer ( There is a risk that the dispersive power with time may be reduced due to an increase in the amount of inorganic anions due to an increase in the amount of inorganic anion and the amount of hypophosphorous acid (salt) and / or bisulfite that are not incorporated into the polymer ends.
In addition, as described above, by adding a certain amount of hypophosphorous acid (salt) and / or bisulfite, the hue of the (meth) acrylic acid polymer aqueous solution is improved due to the reducing action. There is a tendency.

(Decomposition catalyst, reducing compound)
The poly (meth) acrylic acid polymer of the present invention is produced using a polymerization initiator decomposition catalyst or a reducing compound (also referred to as a reaction accelerator) in addition to the polymerization initiator (added to the polymerization system). You may do it.

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 must not significantly interfere with the polymerization reaction in the production of the poly (meth) acrylic acid polymer of the present invention. , And 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.

  In addition, 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, sulfites, sulfate esters, bisulfites, and thiosulfuric acid. Sulfur-containing compounds such as salts, sulfoxylate, benzenesulfinic acid and its substitutes, and homologues of cyclic sulfinic acid such as para-toluenesulfinic acid; phosphorous acid, phosphite, hypophosphorous acid, hypophosphorous acid Phosphorus-containing compounds such as salts and hydrates thereof; octyl mercaptan, dodecyl mercaptan, mercaptoethanol, α-mercaptopropionic acid, thioglycolic acid, thiopropionic acid, α-thiopropionic acid sodium sulfopropyl ester, α-thio Mercapto compounds such as sodium propionate sulfoethyl ester; hydrazine, β-hydro Phenoxyethyl hydrazine, nitrogen-containing compounds such as hydroxylamine, formaldehyde, acetaldehyde, propionaldehyde, 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 addition to the polymerization initiator, chain transfer agent, and reaction accelerator, the method for producing the poly (meth) acrylic acid polymer of the present invention can use a pH adjuster, a buffering agent, and the like as necessary. .

(Polymerization solution)
The poly (meth) acrylic acid polymer of the present invention is preferably produced by solution polymerization. In the manufacturing method of this invention, since the color tone of the polymer (composition) obtained improves, it is preferable to use a C1-C6 alcohol. Moreover, it is preferable that a solvent contains water from a soluble viewpoint of a poly (meth) acrylic-acid type polymer. Therefore, it is most preferable to use a mixed solvent of water and an alcohol having 1 to 6 carbon atoms. In this case, another solvent may be used, but even if another organic solvent is used because the solvent removal step can be simplified, it is 10% with respect to 100% by mass of the reaction liquid after completion of the polymerization. It is preferable to set it as mass% or less, It is further preferable to set it as 5 mass% or less, It is more preferable to set it as 1 mass% or less.
Here, as the solvent that can be used together with (or in addition to) water and alcohol having 1 to 6 carbon atoms during polymerization, amides such as dimethylformaldehyde; ethers such as diethyl ether and dioxane are suitable. 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 manufacturing conditions)
For the poly (meth) acrylic acid polymer of the present invention, any of polymerization methods of batch type (batch type), continuous type and semi-continuous type can be adopted. 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 65 ° C. or higher, more preferably 70 to 110 ° C., and further preferably 75 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.

[Use of poly (meth) acrylic acid polymer (aqueous solution, composition)]
The poly (meth) acrylic acid polymer of the present invention, the poly (meth) acrylic acid polymer aqueous solution, and the poly (meth) acrylic acid polymer composition (hereinafter also referred to as the polymer of the present invention) are water. It can be used as a treatment agent, 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 or polymer composition of the present invention to at least one selected from the group consisting of a dye, a peroxide and a surfactant is, for example, the whiteness of the fiber, color unevenness, dyeing tempering degree In order to improve the fiber treatment agent, at least one selected from the group consisting of a dye, a peroxide and a surfactant is 0.1 per 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 a composition blended at a ratio of ˜100 parts by weight as a fiber treatment 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 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 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 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, and solid content of the polymer aqueous solution 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 (mass) at the second inflection point−1N HCl amount (mass) at the first inflection point) × HCl titer / analyte amount (mass) .
The amount of analyte represents the mass of the analyzed poly (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.

<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 added, the number of revolutions was increased to 1000 rpm at a stretch. 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 Hitachi laser particle size distribution analyzer LA-910.
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).

<Example 1>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade) and jacket, supply path (for polymerization composition and neutralizing agent) provided in the polymerization kettle, In addition, polymerization was carried out using a reaction apparatus having a reflux cooling apparatus and a solvent distillation apparatus under the following polymerization prescription and conditions. 215 parts by mass of ion-exchanged water and 300 parts by mass of isopropyl alcohol (hereinafter also referred to as “IPA”) were charged. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature was raised under normal pressure until the mixed solution was refluxed by an external jacket (the temperature of the mixed solvent was 80 ° C.).
Next, 900 parts by weight of an 80% by weight acrylic acid aqueous solution (hereinafter also referred to as “80% AA”), 83 parts by weight of a 45% sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”), and 15 parts by weight 80% AA and 45% SHP for 150 minutes and 15% NaPS for 80% from a tip nozzle through 67% by mass of a sodium persulfate aqueous solution (hereinafter also referred to as “15% NaPS”) through separate supply paths. At the same time as AA, the dropping was started and dropped over 155 minutes (that is, until 5 minutes after the completion of dropping of 80% AA). The dropping of each component was continuously performed at a constant dropping rate. After completion of the dropwise addition of 15% NaPS, the mixture solution was aged for 30 minutes while maintaining the refluxed state.
After completion of the aging, 583 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 70%) was dropped into the polymerization kettle from the tip nozzle through the supply path to partially neutralize the polymer, and then 45% 80 parts by mass of SHP was added to the polymerization kettle. Next, after the IPA and water mixture is distilled off at 80 to 103 ° C. until there is no IPA in the polymerization kettle, 320 parts by mass of ion-exchanged water is put into the polymerization kettle so that the solution temperature becomes 80 ° C. did. Subsequently, 171 parts by mass of monoethanolamine (AA neutralization rate: 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path to neutralize the polymer. As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (1) was obtained.
The obtained aqueous solution (1) (referred to as polymer aqueous solution (1)) had a solid content value of 52.5% and an active ingredient value of 40.3%. The Brookfield viscosity of the aqueous polymer solution (1) was 810 mPa · s, the polymerization average molecular weight (Mw) was 4500, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.15. 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 23900 ppm. The hue (APHA) in the form of 1) was 40.
The polymerization prescription is shown in Table 1, and the analysis results of the polymer are shown in Table 2.
When the slurry viscosity of heavy calcium carbonate was evaluated by the above method, the slurry viscosity immediately after pulverization was 1050 mPa · s, and the slurry viscosity after 1 week was 3800 mPa · s.

<Example 2>
A sodium polyacrylate / monoethanolamine 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. The obtained aqueous solution (referred to as polymer aqueous solution (2)) had a solid content value of 57.1% and an active ingredient value of 40.2%. The Brookfield viscosity of the aqueous polymer solution (2) was 980 mPa · s, the polymerization average molecular weight (Mw) was 4700, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.18. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the aqueous polymer solution (2) (mainly sulfate ions and hypophosphite ions were detected) was 23600 ppm. The hue (APHA) in the form of 2) was 50. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 1020 mPa · s, and the slurry viscosity after 1 week was 3400 mPa · s.

<Example 3>
A sodium polyacrylate / monoethanolamine aqueous solution (3) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (3)) had a solid content value of 57.4% and an active ingredient value of 40.4%. The Brookfield viscosity of the aqueous polymer solution (3) was 990 mPa · s, the polymerization average molecular weight (Mw) was 4900, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.21. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the aqueous polymer solution (3) (mainly sulfate ions and hypophosphite ions were detected) was 7800 ppm. The hue (APHA) in the form of 3) was 120. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 900 mPa · s, and the slurry viscosity after one week was 3000 mPa · s.

<Example 4>
A sodium polyacrylate / monoethanolamine aqueous solution (4) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (4)) had a solid content value of 57.0% and an active ingredient value of 39.9%. The Brookfield viscosity of the aqueous polymer solution (4) was 960 mPa · s, the polymerization average molecular weight (Mw) was 4600, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.17. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the polymer aqueous solution (4) was 34800 ppm. The hue (APHA) in the form of 4) was 20. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 1100 mPa · s, and the slurry viscosity after 1 week was 4000 mPa · s.

<Example 5>
A sodium polyacrylate / monoethanolamine aqueous solution (5) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. “35% SBS” described in Table 1 represents a 35% aqueous sodium bisulfite solution. The obtained aqueous solution (referred to as polymer aqueous solution (5)) had a solid content value of 56.7% and an active ingredient value of 39.7%. The Brookfield viscosity of the aqueous polymer solution (5) was 960 mPa · s, the polymerization average molecular weight (Mw) was 4800, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.21. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the polymer aqueous solution (5) was 8200 ppm. The hue (APHA) in the form of 5) was 120. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 1000 mPa · s, and the slurry viscosity after 1 week was 3400 mPa · s.

<Example 6>
A sodium polyacrylate / monoethanolamine aqueous solution (6) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (6)) had a solid content value of 57.4% and an active ingredient value of 40.4%. The Brookfield viscosity of the aqueous polymer solution (6) was 970 mPa · s, the polymerization average molecular weight (Mw) was 4800, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.19. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the polymer aqueous solution (6) (mainly sulfate ions and hypophosphite ions were detected) was 35500 ppm. The hue (APHA) in the form of 6) was 20. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 1150 mPa · s, and the slurry viscosity after one week was 4200 mPa · s.

<Comparative Example 1>
A sodium polyacrylate / monoethanolamine salt aqueous solution (7) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those shown in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (7)) had a solid content value of 56.7% and an active ingredient value of 39.6%. The Brookfield viscosity of the aqueous polymer solution (7) was 1210 mPa · s, the polymerization average molecular weight (Mw) was 6200, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.29. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the polymer aqueous solution (7) was 4500 ppm. The hue (APHA) in the form of 7) was 220. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
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 1200 mPa · s, and the slurry viscosity after one week was 4500 mPa · s.

<Comparative example 2>
A sodium polyacrylate / monoethanolamine salt aqueous solution (8) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those shown in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (8)) had a solid content value of 59.1% and an active ingredient value of 39.2%. The Brookfield viscosity of the aqueous polymer solution (8) was 980 mPa · s, the polymerization average molecular weight (Mw) was 4800, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.18. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the polymer aqueous solution (8) was 44000 ppm. The hue (APHA) in the form of 8) was 20. The polymerization prescription is shown in Table 1, and the measurement results and evaluation results of the obtained polymers are shown in Table 2.
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 2500 mPa · s, and the slurry viscosity after one week was 5100 mPa · s.

<Comparative Example 3>
A sodium polyacrylate / monoethanolamine salt aqueous solution (9) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those shown in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (9)) had a solid content value of 58.7% and an active ingredient value of 39.3%. The Brookfield viscosity of the aqueous polymer solution (9) was 970 mPa · s, the polymerization average molecular weight (Mw) was 4700, and the polymerization average molecular weight (Mw) / number average molecular weight (Mn) was 2.20. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the polymer aqueous solution (9) was 45500 ppm. The hue (APHA) in the form of 9) was 20. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
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 3000 mPa · s, and the slurry was gelled after one week, so the slurry viscosity could not be measured. It was.

  Table 1 shows the polymerization prescription and the polymerization results. The evaluation results and the structure derived from (meth) acrylic acid (salt) and the organic amine (salt) contained in the aqueous solution containing the poly (meth) acrylic acid polymer. Table 2 summarizes the “molar ratio of the structures to be formed”.

From the results shown in Tables 1 and 2, it has been clarified that the polymer of the present invention has an excellent color tone and good initial dispersibility and dispersibility over time.

Claims (3)

An aqueous solution containing a poly (meth) acrylic acid polymer,
The poly (meth) acrylic acid polymer is polymerized in the presence of an alcohol having 1 to 6 carbon atoms,
At least a part of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine,
The molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) contained in the aqueous solution is 100: 10 to 100: 75,
The concentration of inorganic anions containing sulfur atoms or phosphorus atoms contained in the aqueous solution is 5000 to 40000 ppm with respect to the aqueous solution,
An aqueous solution characterized in that A pigment dispersant comprising the aqueous solution according to claim 1. The method for producing an aqueous solution according to claim 1, wherein the (meth) acrylic acid monomer is polymerized in the presence of an alcohol having 1 to 6 carbon atoms.