JP6178880B2 - Poly (meth) acrylic acid polymer aqueous solution and method for producing the same - Google Patents

Description

The present invention relates to a poly (meth) acrylic acid polymer aqueous solution and a production method thereof, and an inorganic particle slurry and a production method thereof. More specifically, the poly (meth) acrylic acid polymer aqueous solution, which excels in color tone, pigment dispersion, etc., and low viscosity, little change in viscosity over time, little coloring during drying, and high pH can be maintained. The present invention relates to an inorganic particle slurry.

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, polymers with higher performance are required.

As a method for meeting such a demand, for example, Patent Document 1 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, which is a monomer of a chain transfer agent. Disclosed is a method for producing a water-soluble polymer, characterized in that the rate of addition to is changed at least once.
Further, for example, in Patent Document 2, a monomer component composed of a monocarboxylic acid (salt) monoethylenically unsaturated monomer or the like 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.
Further, for example, in Patent Document 3, a compound containing calcium or the like is reacted in a range of 1 to 70 parts per 100 parts with respect to a polymer of α, β monoethylenically unsaturated carboxylic acid, etc. A retained polymer is disclosed.

In addition, inorganic particle slurries are widely used in the paper industry and ceramic industry for the purpose of coating and molding inorganic particles.

As a conventional inorganic particle slurry, for example, Patent Document 3 discloses a compound containing calcium or the like in the range of 1 to 70 parts per 100 parts of a polymer of α and β monoethylenically unsaturated carboxylic acids. , And a calcium carbonate slurry prepared by using a polymer maintained at a pH of 4 or higher is disclosed. Patent Document 4 discloses a neutralized product of a (co) polymer (A) composed of 50 to 100 mol% of α, β-unsaturated carboxylic acid and 0 to 50 mol% of another monomer as structural units. 10 to 99.99 mol% of the acid group in (A) is an alkali metal or alkaline earth metal salt, 0.01 to 5 mol% is a salt of an organic amine, and 0 to 89.99 Disclosed are pigment dispersants and dispersion slurries characterized in that the mole percent is a free acid group.

In addition, Patent Document 5 discloses (meth) acrylic acid (co) polymers, etc., and (meth) acrylate units contained in the polymer are (meth) acrylic acid alkali metal salt units 49.9 to 49.9- Wet pulverization of heavy calcium carbonate using a polymer composed of 99 mol parts, 0.1 to 10 mol parts of alkaline earth metal salt units of (meth) acrylate and 0 to 10 mol parts of ammonium salt units of (meth) acrylate A heavy calcium carbonate slurry is disclosed that is manufactured including the following steps.

JP-A-2005-139469 Japanese Patent Laid-Open No. 2002-80502 JP 54-82416 A Japanese Patent No. 2984926 International Publication No. 2004/087574

As described above, various studies have been made on polymers used in detergent builders, pigment dispersants, and the like, and inorganic particle slurries.
For example, the polymer obtained by the production method disclosed in Patent Document 1 can reduce the amount of residual monomers, and can narrow the molecular weight distribution of the obtained polymer, thereby further improving calcium carbonate. It is said that the dispersibility of can be shown. The polymer obtained by the production method disclosed in Patent Document 2 is said to exhibit good pigment dispersibility. Further, the polymer disclosed in Patent Document 3 is said to show a good pigment dispersion effect with a small amount of addition.
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, especially dispersibility with little change over time.
Further, for example, when used in a dispersant for a paper processing pigment slurry, in addition to the above performance, a polymer composition with less coloring is required so as not to affect the whiteness of the paper.

Further, the inorganic particle slurry is usually required to have a high concentration of inorganic particles and a viscosity that is easy to process. In addition, since a certain period is required from production to use, it is required to show viscosity stability over time. On the other hand, the slurry disclosed in Patent Document 3 is said to have low viscosity and good temporal stability. The dispersion slurry disclosed in Patent Document 4 is said to have a relatively small increase in slurry viscosity after standing for 7 days. Moreover, the slurry disclosed in Patent Document 5 is said to have a low viscosity and a viscosity after 7 days.
However, for example, with recent increases in the speed and precision of slurry coating machines, there has been an increasing demand for inorganic particle slurries that exhibit more stringent dispersibility of inorganic particle slurries than conventional ones, in particular, viscosity with little change with time.

Thus, although various polymers and inorganic particle slurries have been reported in the past, there is a demand for the development of those that are further adapted to the current needs described above.
Therefore, the present invention provides a polymer (aqueous solution) that is excellent in inorganic dispersibility and the like and exhibits sufficient dispersibility over time, a polymer (aqueous solution) that also has a good color tone over time, and the like. It aims at providing the method of manufacturing a polymer (aqueous solution) simply.
The present invention also provides an inorganic particle slurry that exhibits high inorganic particle concentration and good viscosity, has sufficient viscosity stability over time, has little coloration during drying, and can maintain a high pH, and the inorganic particle slurry. It aims at providing the method of manufacturing simply.

The inventors of the present invention have conducted intensive studies on the polymer (aqueous solution) and the production method thereof in order to solve the above problems. As a result, it was found that a specific aqueous solution containing a polyacrylic acid polymer (partially) neutralized with an organic amine exhibits good dispersibility of inorganic substances and sufficient dispersibility with time stability. The invention has been 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 at least one of the carboxyl groups of the poly (meth) acrylic acid polymer. The part is neutralized with an organic amine, and 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. The molar ratio is 100: 10 to 100: 75, and the concentration of the inorganic anion containing a sulfur atom or phosphorus atom contained in the poly (meth) acrylic acid polymer aqueous solution is the poly (meth). It is an aqueous solution characterized by being 1000 to 10,000 ppm with respect to the acrylic acid polymer aqueous solution.

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 is a method for producing an aqueous solution containing the poly (meth) acrylic acid polymer of the present invention, wherein the acid type and / or part thereof is used. A method for producing an aqueous poly (meth) acrylic acid polymer solution, comprising a step of neutralizing an aqueous solution containing a Japanese-type poly (meth) acrylic acid polymer with an organic amine.

Then, a specific aqueous solution containing a polyacrylic acid polymer (partially) neutralized with the above organic amine is further manufactured by a specific manufacturing method, whereby a polymer (aqueous solution) having a good color tone over time. Has been found, and the present invention has been completed.
That is, an aqueous solution containing a poly (meth) acrylic acid polymer, wherein at least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized with an organic amine, and the poly (meth) The molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) contained in the aqueous acrylic acid polymer solution is 100: 10 to 100: 75, and the above The concentration of the inorganic anion containing a sulfur atom or a phosphorus atom contained in the poly (meth) acrylic acid polymer aqueous solution is 1000 to 10,000 ppm with respect to the poly (meth) acrylic acid polymer aqueous solution, and The poly (meth) acrylic acid polymer aqueous solution includes (i) a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an alkali metal salt; (Ii) A poly (meth) acryl produced essentially comprising a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an organic amine. An aqueous acid polymer solution is also one aspect of the present invention.

An aqueous solution containing a poly (meth) acrylic acid polymer, wherein at least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized with an organic amine, and the poly (meth) The molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) contained in the aqueous acrylic acid polymer solution is 100: 10 to 100: 75, and the above The concentration of the inorganic anion containing a sulfur atom or a phosphorus atom contained in the poly (meth) acrylic acid polymer aqueous solution is 1000 to 10,000 ppm with respect to the poly (meth) acrylic acid polymer aqueous solution, and The poly (meth) acrylic acid polymer aqueous solution comprises (i) a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an alkali metal salt, i) a step of neutralizing an aqueous solution containing a partially neutralized poly (meth) acrylic acid polymer neutralized with an alkali metal salt with an organic amine, A meth) acrylic acid polymer aqueous solution is also one aspect of the present invention.

Another aspect of the present invention provides a method for producing an aqueous poly (meth) acrylic acid polymer solution. That is, it is a method for producing an aqueous solution containing the poly (meth) acrylic acid polymer of the present invention, and (i) an aqueous solution containing an acid type and / or a partially neutralized poly (meth) acrylic acid polymer. And (ii) a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an organic amine as essential components. The method for producing a poly (meth) acrylic acid polymer aqueous solution characterized by the above is also one aspect of the present invention.

Moreover, it is a method for producing an aqueous solution containing the poly (meth) acrylic acid polymer of the present invention, and (i) an aqueous solution containing an acid type and / or a partially neutralized poly (meth) acrylic acid polymer. And (ii) a step of neutralizing an aqueous solution containing a partially neutralized poly (meth) acrylic acid polymer neutralized with the alkali metal salt with an organic amine. A method for producing a poly (meth) acrylic acid polymer aqueous solution, which is essential, is also one aspect of the present invention.

In addition, the present inventors conducted intensive research on the inorganic particle slurry and the production method thereof in order to solve the above problems. As a result, the inorganic particle slurry containing a specific composition containing a polyacrylic acid polymer (partially) neutralized with an organic amine exhibits good viscosity and sufficient viscosity stability over time, It has been found that there is little coloring during drying and a high pH can be maintained, and the present invention has been completed.
That is, the inorganic particle slurry according to the present invention is an inorganic particle slurry containing a poly (meth) acrylic acid polymer, and at least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is 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 inorganic particle slurry is 100: 10 to 100: 75. The concentration of inorganic anions containing sulfur atoms or phosphorus atoms contained in the inorganic particle slurry is 100 to 400 ppm with respect to the inorganic particle slurry, and the inorganic particles contained in the inorganic particle slurry are all inorganic. 90-100% by mass of particles having a particle size of 2 μm or less is included with respect to 100% by mass of the particles, and the solid content concentration of the inorganic particle slurry is 75% by mass or more. Inorganic particle slurry, wherein the door.

From another aspect of the present invention, a method for producing an inorganic particle slurry is provided. That is, the method for producing an inorganic particle slurry of the present invention is a method for producing an inorganic particle slurry comprising a step of adding an aqueous solution containing a poly (meth) acrylic acid polymer to inorganic particles and crushing the inorganic particles. In addition, at least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized with an organic amine, and the structure derived from (meth) acrylic acid (salt) and the organic amine contained in the aqueous solution. The molar ratio of the structure derived from (salt) is 100: 10 to 100: 75, and the concentration of inorganic anions containing sulfur atoms or phosphorus atoms contained in the aqueous solution is 1000 to 100 with respect to the aqueous solution. It is a manufacturing method of the inorganic particle slurry which is 10000 ppm.

The aqueous poly (meth) acrylic acid polymer solution of the present invention has excellent dispersibility of inorganic fine particles such as mud stains and inorganic pigments, and can exhibit a dispersive power over time. Further, by producing by a specific production method, it has an excellent color tone over time. Therefore, when used as a detergent builder or a pigment dispersant, excellent detergency and stable dispersibility of the pigment over time can be obtained.
According to the method for producing a poly (meth) acrylic acid polymer aqueous solution of the present invention, the poly (meth) acrylic acid polymer aqueous solution of the present invention can be produced efficiently and simply.
Moreover, since the inorganic particle slurry of the present invention has the characteristics that the inorganic particle content is high, the viscosity is low, and the change in viscosity with time is low, it exhibits excellent moldability of inorganic particles. Therefore, it is preferably used as a pigment slurry for paper coating in the paper industry and ceramic industry.
According to the method for producing an inorganic particle slurry of the present invention, an inorganic particle slurry having excellent viscosity and viscosity stability over time 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 (also referred to as the polymer aqueous solution of the present invention) includes a poly (meth) acrylic acid polymer.
The poly (meth) acrylic acid polymer represents a polymer containing a structure derived from (meth) acrylic acid (salt), and the structure derived from (meth) acrylic acid (salt) ) have a structure acrylic acid (salt) is formed by radical _{polymerization, -CH 2 CR (COOM) -} , in a structure represented. 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. Examples of the metal atom include alkali metal atoms such as Li, Na and K, and alkaline earth metal atoms such as Ca and Mg.
The (meth) acrylic acid (salt) represents acrylic acid, acrylate, methacrylic acid, and methacrylate, and among these, acrylic acid and acrylate are preferable. These (meth) acrylic acids (salts) may be used alone or in combination of two or more.
Examples of the salt in the (meth) acrylic acid (salt) include metal salts, ammonium salts, and organic amine salts. Among these, alkali metal salts are preferable, and sodium salts are more preferable. 1 type may be sufficient as the salt in these (meth) acrylic acid (salt), and 2 or more types may be sufficient as it.

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 groups other than organic amine salt-type carboxyl groups Although the ratio of the salt is not particularly limited, the structure derived from (meth) acrylic acid (salt), organic amine and organic amine salt (this specification) contained in the poly (meth) acrylic acid polymer aqueous solution of the present invention. In the book, it is important that the molar ratio with the structure derived from “organic amine (salt)” is 100: 10 to 100: 75. Preferably, it is 100: 15-100: 70, and it is more preferable that it is 100: 20-100: 65.

The organic amine (salt) may be any of primary amine, secondary amine, tertiary amine, quaternary amine, and salts thereof, and one kind may be used alone, or two or more kinds may be used. You may use together. Examples of such organic amines include alkanolamines such as monoethanolamine, monopropanolamine, diethanolamine, and triethanolamine; alkylamines such as methylamine, ethylamine, butylamine, dimethylamine, and diethylamine; cycloalkyl such as cyclohexylamine. Examples include amines; cyclic amines such as pyrrolidine, piperidine, pyridine, pyrazine, pyrrole and morpholine; and polyalkyleneamines such as ethylenediamine and diethylenetriamine. Among these, the poly (meth) acrylic acid according to the present invention is significantly improved in the pigment dispersion performance with time of the polymer aqueous solution according to the present invention, easy to handle, and relatively inexpensive. The aqueous polymer solution preferably contains a structure derived from alkanolamine or a salt thereof.

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, and / Or represents an organic amine (salt) that remains unreacted.
Here, the structure formed by the reaction of the added organic amine (salt) is, for example, (i) an organic amine (salt) in an aqueous solution containing an acid type and / or a partially neutralized polyacrylic acid polymer. ), The structure contained in the salt of the carboxyl group neutralized with organic amine, and (ii) an organic compound obtained by neutralizing a monomer such as (meth) acrylic acid in advance with organic amine Examples include a structure formed by polymerization of an amine salt, and (iii) a structure formed by reacting an added organic amine (salt) with an acidic substance other than a polyacrylic acid polymer.
Since the pigment dispersion performance with time tends to be improved, the poly (meth) acrylic acid polymer aqueous solution of the present invention is preferably in a form in which the amount of inorganic salt or the like is reduced as much as possible. The structure derived from (salt) is preferably a carboxyl group contained in the polymer and neutralized with an organic amine. Therefore, the ratio of the carboxyl group (organic amine salt type carboxyl group) neutralized with an organic amine to the carboxyl group of 100 mol% of the poly (meth) acrylic acid polymer is 10 to 75 mol%. Is more preferable, 15 to 70 mol% is more preferable, and 20 to 65 mol% is particularly preferable.

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.
Examples of other monomers include carboxyl group-containing monomers other than (meth) acrylic acid, such as maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methyleneglutaric acid, and salts thereof. Salt thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, α- Hydroxyl group-containing alkyl (meth) acrylates such as hydroxymethylethyl (meth) acrylate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic (Meth) acrylic acid such as lauryl acid having 1 to 18 carbon atoms Alkyl (meth) acrylates which are esters of alkyl groups; amino group-containing acrylates such as dimethylaminoethyl (meth) acrylate and quaternized products thereof; amide group-containing single quantities such as (meth) acrylamide, dimethylacrylamide and isopropylacrylamide Vinyl esters such as vinyl acetate; alkenes such as ethylene and propylene; aromatic vinyl monomers such as styrene; maleimide derivatives such as maleimide, phenylmaleimide and cyclohexylmaleimide; nitriles such as (meth) acrylonitrile Group-containing vinyl monomers; monomers having a sulfonic acid group such as 3-allyloxy-2-hydroxypropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, and the like of Salts: Monomers having a phosphonic acid group such as vinylphosphonic acid and (meth) allylphosphonic acid; Aldehyde group-containing vinyl monomers such as (meth) acrolein; Alkyl such as methyl vinyl ether, ethyl vinyl ether and butyl vinyl ether Vinyl ethers; other functional group-containing monomers such as vinyl chloride, vinylidene chloride, allyl alcohol, vinyl pyrrolidone; polyalkylene glycol (meth) acrylate, monoalkoxy polyalkylene glycol (meth) acrylate, vinyl alcohol, (meth) allyl And polyalkylene glycol chain-containing monomers such as monomers having a structure in which 1 to 300 mol of alkylene oxide is added to an unsaturated alcohol such as alcohol or isoprenol. 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. If it is 80 mass% or more, it exists in the tendency for the pigment dispersion performance with time of the polymer aqueous solution of this invention to improve more. More preferably, it is 90 mass% or more.
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 poly (meth) acrylic acid polymer of the present invention has a structure derived from other monomers with respect to 100% by mass of the structure derived from all monomers contained in the poly (meth) acrylic acid polymer of the present invention. It is preferable that it is 0-20 mass%, and it is more preferable that it is 0-10 mass%.

Specifically, the weight average molecular weight of the poly (meth) acrylic acid polymer of the present invention is preferably 3,000 to 50,000, more preferably 4,000 to 30,000, and still more preferably. Is 5,000 to 20,000. If 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 sufficient performance as a detergent builder or 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 value of this 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 substance is wet pulverized may increase. Moreover, when too large, there exists a possibility that the temporal viscosity stability 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.

The poly (meth) acrylic acid polymer of the present invention or the aqueous solution containing the poly (meth) acrylic acid polymer of the present invention (in the present specification, these are combined and simply referred to as “poly (meth) acrylic acid system” "Polymer (aqueous solution)" or "polymer (aqueous solution)"), as described in [Method for producing poly (meth) acrylic acid polymer (aqueous solution)] (i) ) A step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an alkali metal salt; and (ii) an acid type and / or partially neutralized poly (meta) ) It is preferable to produce an aqueous solution containing an acrylic acid polymer as an essential step. The poly (meth) acrylic acid polymer (aqueous solution) of the present invention thus produced further has a good color tone (less color) over time. More preferably, (i) a step of neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an alkali metal salt; and (ii) neutralizing with the alkali metal salt. And the step of neutralizing the aqueous solution containing the partially neutralized poly (meth) acrylic acid polymer with an organic amine.

[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 aqueous polymer solution (the total content of (meth) acrylic acid (salt) and other monomers) depends on the type of monomer used. Although different, it is preferably less than 1% by mass with respect to 100% by mass of the solid content of the polymer aqueous solution. More preferably, it is less than 0.5 mass%, More preferably, it is less than 0.1 mass%.

Although the said poly (meth) acrylic-acid type polymer aqueous solution is not restrict | limited in particular, After manufacturing a poly (meth) acrylic-acid type polymer in the aqueous solvent mentioned later, it passes through purification processes, such as impurity removal. Although what is manufactured may be sufficient, what is obtained without passing through a refinement | purification process from a viewpoint of production efficiency is preferable. Furthermore, after the polymerization step of synthesizing a poly (meth) acrylic acid polymer in an aqueous solvent, the obtained polymer aqueous solution is diluted with a small amount of water for convenience of handling (the obtained polymer). What was concentrated to about 1 to 400% by mass with respect to 100% by mass of the aqueous solution) or concentrated is also included in the poly (meth) acrylic acid polymer aqueous solution of the present invention.

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 50 to 500% by mass, more preferably 60 to 400% by mass, and still more preferably 80 to 300% by mass with respect to 100% by mass of the poly (meth) acrylic acid polymer. 90 to 200% by mass is most preferable.
In addition, the content of the poly (meth) acrylic acid polymer of the present invention in the polymer aqueous solution of the present invention is 16 to 66% by mass with respect to 100% by mass of the poly (meth) acrylic acid polymer aqueous solution. It is preferably 20 to 62% by mass, more preferably 25 to 55% by mass.

As will be described later, from the limitation on the use of the poly (meth) acrylic acid polymer aqueous solution, and from the viewpoint of performance improvement, the content of the organic solvent in the polymer aqueous solution of the present invention is preferably reduced as much as possible. For example, with respect to 100% by mass of the poly (meth) acrylic acid polymer aqueous solution, the content of the organic solvent is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less.

The poly (meth) acrylic acid polymer aqueous solution of the present invention is characterized in that the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is 1000 to 10,000 ppm with respect to the polymer aqueous solution of the present invention. When the concentration of the inorganic anion containing a sulfur atom or phosphorus atom exceeds 10,000 ppm, the pigment dispersion performance with time of the polymer aqueous solution tends to deteriorate. If the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is set to less than 1000 ppm, it will be difficult to produce a polymer aqueous solution having excellent pigment dispersion performance over time.
Examples of the inorganic anion containing sulfur atom or phosphorus atom include sulfate ion, sulfite ion, phosphate ion, phosphite ion, hypophosphite ion 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 preferably has a viscosity (25 ° C.) of 400 to 2000 mPa · s when the solid content (nonvolatile content) concentration is adjusted to 35 to 70 mass%. 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 500-1500 mPa * s, More preferably, it is 550-1000 mPa * s, Especially preferably, it is 600-900 mPa * s, Most preferably, it is 600-800 mPa * s.
The viscosity was measured using a B-type viscometer. The value measured at 4, 60 rpm for 5 minutes.

The aqueous poly (meth) acrylic acid polymer solution of the present invention preferably has a pH of 2.5 to 9.0 when the solid content (nonvolatile content) concentration is adjusted to 35 to 70 mass%. 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 4.0-8.5, More preferably, it is 4.5-8.0. Most preferably, it is 5.0-8.0.

The poly (meth) acrylic acid polymer aqueous solution of the present invention is preferably less colored. For example, the hue APHA in a polymer aqueous solution immediately after production and after one month at room temperature (25 ° C.) is 200 or less. It is preferable that it is, and it is more preferable that it is 180 or less. More preferably, it is 160 or less. According to the method for producing a poly (meth) acrylic acid polymer aqueous solution of the present invention, it is possible to suppress coloring of the polymer aqueous solution to a low level (to make the color tone good). When there is little coloring, it can use preferably for a dispersing agent use or detergent builder use, for example.
APHA can be measured with a color difference meter or the like.

[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.
In addition, content of the unreacted monomer contained in the poly (meth) acrylic acid polymer composition of the present invention, the content of a solvent or an organic solvent, the poly (meth) acrylic acid polymer of the present invention The content, concentration of inorganic anion containing sulfur atom or phosphorus atom, viscosity, pH, and APHA are preferably the same as those of the poly (meth) acrylic acid polymer aqueous solution of the present invention described above.

[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-described other monomers in addition to (meth) acrylic acid (salt). (Meth) acrylic acid based on 100% by mass of all monomers (referring to the sum 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 (salt) is preferably 80% by mass or more in terms of acid type. If it is 80 mass% or more, the pigment dispersion performance with time of the obtained polymer aqueous solution tends to be improved. More preferably, it is 90 mass% or more.
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 method for producing the poly (meth) acrylic acid polymer (aqueous solution) of the present invention, it is preferable to use acrylic acid or acrylate 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 this production method, the color tone of the resulting polymer aqueous solution becomes particularly good, and when used as a pigment (inorganic particle) dispersant, for example, it tends to exhibit particularly good dispersibility. Examples of the organic amine used in the neutralizing step (or the adding step) include the same organic amines as described above. Preferably, the pigment dispersion performance with time of the aqueous polymer solution is remarkable. Since it improves, it is an alkanolamine.

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 that case, 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 the step of neutralizing, and then performing the step of neutralizing the aqueous solution containing the acid-type and / or partially neutralized polyacrylic acid polymer with an organic amine because the color tone is good. However, the reverse process order 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 is in the above-described range, Excess organic amine (salt) may be added beyond the neutralization point. By setting 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 to the above-mentioned range, The aqueous solution of (meth) acrylic acid polymer will remarkably develop the dispersion power of the pigment over time.
Other neutralizing agents other than the above 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, alkaline earth metals A salt, ammonia, etc. are mentioned.
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 partially neutralized poly (meth) acrylic acid polymer with an organic amine (or acid type and In the case where it is produced by adding an organic amine to an aqueous solution containing a partially neutralized poly (meth) acrylic acid polymer, this step is also referred to as “step N2”), ) A step of producing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer by polymerizing acrylic acid (salt) as an essential component (this step is also referred to as “step B”) It is preferable to produce it. In this case, the neutralization rate (total acid groups (neutralized and unneutralized) of the acid type and / or partially neutralized poly (meth) acrylic acid-based polymer (after step B) produced in step B The ratio of acid groups neutralized with respect to the colorant is preferably 0 to 90%, more preferably 0 to 85%, because the color tone tends to improve over time in pigment dispersion performance and aqueous solution. 35% is more preferable, and 0 to 10% is particularly preferable.

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 (this It is preferable to manufacture the process including “process C”. Although the order in which the process C is performed is not particularly limited, the process C is particularly preferably performed after the process B. As the neutralization rate of the partially neutralized poly (meth) acrylic acid polymer produced after Step C (after Step C), the color tone tends to be improved, so 5 to 90% is preferable. 10 to 85% is more preferable, and 15 to 80% is particularly preferable.

As a method for producing the poly (meth) acrylic acid polymer (aqueous solution) of the present invention, among the methods described above, an aqueous solution containing an acid-type and / or partially neutralized poly (meth) acrylic acid-based polymer is used. A step of neutralizing (partially neutralizing) with an alkali metal salt (this step is also referred to as “step N1”) and an aqueous solution containing an acid-type and / or partially-neutralized poly (meth) acrylic acid polymer are organic A form including the step of neutralizing with an amine (step N2) as an essential component is particularly preferable. By setting it as such a form, it becomes possible to make the color tone of the poly (meth) acrylic-acid type polymer (aqueous solution) obtained favorable with time.

Neutralization rate by alkali metal salt of partially neutralized poly (meth) acrylic acid polymer after step N1 (mol% of acid groups neutralized by alkali metal salt relative to 100 mol% of total acid groups) As, since it exists in the tendency for the color tone of the polymer aqueous solution obtained to improve, 25-90 mol% is preferable, 30-85 mol% is more preferable, and 35-80 mol% is especially preferable.

Examples of the alkali metal salt used in the step N1 include hydroxides such as Li, Na, and K, carbonates, bicarbonates, and the like, and lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, Examples thereof include sodium bicarbonate and potassium carbonate. In step N1, an alkali metal salt is used as an essential component, but another alkaline substance (neutralizing agent) such as an alkaline earth metal salt may be used in combination. In this case, it is preferable that an alkali metal salt is 80 mol% or more with respect to 100 mol% of all the neutralizing agents used for process N1.

Although the temperature of the said process N1 should just be suitably selected according to the kind of alkali metal salt to be used, it is preferable to carry out at 40-100 degreeC, 45-95 degreeC is more preferable, and 50-90 degreeC is especially preferable. . If the neutralization reaction is performed at a temperature exceeding 100 ° C., the color tone of the resulting aqueous polymer solution may deteriorate, such being undesirable. Moreover, when neutralizing at the temperature lower than 40 degreeC, it is necessary to cool the polymer aqueous solution obtained after superposition | polymerization to the temperature lower than 40 degreeC, and it is not preferable from the surface of productivity.
Further, the time required for the step N1 may be appropriately selected according to the type and amount of the alkali metal salt to be used, but is usually preferably 10 hours or less, more preferably 5 hours or less, and further preferably 3 hours or less. .

The neutralization rate by the organic amine of the partially neutralized poly (meth) acrylic acid polymer after Step N2 (mol% of acid groups neutralized by organic amine with respect to 100 mol% of total acid groups) is: From the aspect of improving the dispersive power of the resulting aqueous polymer solution over time, the poly (meth) acrylic acid polymer aqueous solution, preferably an organic amine (salt) contained in the poly (meth) acrylic acid polymer. The molar ratio of the structure derived from is preferably set in the above range.

Examples of the organic amine used in the step N2 are the same as those exemplified above, but alkanolamine is preferable because the pigment dispersion performance with time of the aqueous polymer solution is remarkably improved. Amines are particularly preferred. In step N2, an organic amine is used as an essential component, but other alkali substances (neutralizing agents) may be used in combination. The neutralizing agent is the same as other neutralizing agents other than the organic amine described above. In this case, it is preferable that an organic amine is 80 mol% or more with respect to 100 mol% of all the neutralizing agents used for process N2.

Although the temperature of the said process N2 should just be suitably selected according to the kind of organic amine to be used, it is preferable to carry out at 40-100 degreeC, 45-95 degreeC is more preferable, and 50-90 degreeC is especially preferable. If the neutralization reaction is performed at a temperature exceeding 100 ° C., the color tone of the resulting aqueous polymer solution may deteriorate, such being undesirable. Moreover, when neutralizing at the temperature lower than 40 degreeC, it is necessary to cool the polymer aqueous solution obtained after superposition | polymerization to the temperature lower than 40 degreeC, and it is not preferable from the surface of productivity.
Further, the time required for the step N2 may be appropriately selected according to the type and amount of the organic amine to be used, but is usually preferably 10 hours or less, more preferably 5 hours or less, and further preferably 3 hours or less.

In the form of the manufacturing method including the step N1 and the step N2 as essential, the order of the step N1 and the step N2 is not particularly limited, the step N1 may be performed first, and the step N2 first. The process N1 and the process N2 may be performed simultaneously. However, since organic amines may be colored due to heat history or the like, it is preferable to avoid exposure to high temperature for a long time, and therefore, step N1 is preferably performed first. When step N1 is performed first, it is possible to perform a part of the steps, for example, at the time when 50 mol% or more of the alkali metal salt added in step N1 is added to the reaction solution. It is also possible to start step N2. More preferably, the step N2 is started when 70 mol% or more of the alkali metal salts added in the step N1 are added, and more preferably, 90% of the alkali metal salts added in the step N1. It is a time when mol% or more is added, and most preferably, the step N2 is started after the addition of the alkali metal salt added in the step N1 is completed. By performing the neutralization step (steps N1 and N2) in the above order, it becomes easy to adjust the pH within the above preferred range, the color tone of the resulting aqueous polymer solution becomes particularly good, and for example, a pigment dispersant When used as, it tends to exhibit particularly good dispersibility.

In the form of the production method including the step N1 and the step N2 as essential, it is preferable to produce the poly (meth) acrylic acid polymer including the step B.

As described later in (Polymerization solution), the poly (meth) acrylic acid polymer of the present invention is preferably produced by solution polymerization. In this case, water or a mixed solvent of water and an organic solvent is used. be able to. When an organic solvent is used, a solvent removal step (step D) is required, but step D may be performed before the neutralization step (steps N1 and N2), or a neutralization step (steps N1 and N2). Or after the neutralization step N1 and the neutralization step N2. Considering the conditions of each process, such as the temperature and pressure during polymerization, the temperature and pressure during neutralization, and the temperature and pressure during solvent removal, the coloration of the resulting aqueous poly (meth) acrylic acid polymer solution can be kept low. The order of the process D, the process N1, and the process N2 may be appropriately selected so as to be able to be performed, and is not particularly limited. However, since the organic amine may be colored due to a heat history or the like, the process N2 is performed last. Is more preferable. That is, the order in which the process D is performed first, then the process N1 is performed, and the process N2 is performed last, or the process N1 is performed first, then the process D is performed, and the process N2 is performed finally. preferable.

(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.
As the polymerization initiator, those usually used as polymerization initiators can be used, for example, persulfates such as sodium persulfate, potassium persulfate, ammonium persulfate; hydrogen peroxide; dimethyl 2,2 '-Azobis (2-methylpropionate), 2,2'-azobis (2-amidinopropane) hydrochloride, 4,4'-azobis-4-cyanoparerenic acid, azobisisobutyronitrile, 2,2' -Azo compounds such as azobis (4-methoxy-2,4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide Etc. are suitable. 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.
Although the usage-amount of the said polymerization initiator is not restrict | limited in particular, It is preferable that it is 15 g or less with respect to 1 mol of all the monomer components. More preferably, it is 0.1-12g.

Among the above polymerization initiators, it is particularly 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 preferably, it is more preferably 1.2 g or less, and particularly preferably 1.1 g or less. As a minimum of the usage-amount of persulfate, 0.1 g or more is preferable with respect to 1 mol of all the monomers, and 0.5 g or more is more preferable.

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 more preferably 80%. Most preferably, the total amount is not less than mass% and the entire amount is dropped. Thus, it is preferable that the polymerization initiator is continuously dropped, but the dropping speed can be set as appropriate.

The dropping time when the polymerization initiator is continuously dropped is not particularly limited, but ammonium persulfate, potassium persulfate, sodium persulfate under the conditions of polymerization temperature and pH at the time of polymerization described later. In the case of using a relatively quick decomposition initiator such as persulfate, etc., it is preferable to drop until the monomer dropping end time, and it may end within 30 minutes after the monomer dropping ends. More preferably, it is particularly preferably completed within 5 to 20 minutes after completion of the monomer dropping. Thereby, the residual amount of the monomer in a polymer can be reduced significantly. 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 the initiator with relatively quick decomposition, the preferable 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, depending on the case, the dropping of the initiator may be started before the start of dropping of the monomer. In particular, in the case of a combined system using two or more kinds of initiators in combination, one initiator is dropped. May be started, and after a certain period of time has elapsed, or after it has ended, the addition of another initiator may be started. In any case, it may be appropriately set according to the decomposition rate of the initiator and the reactivity of the monomer.

(Chain transfer agent)
In the method for producing a poly (meth) acrylic acid polymer of the present invention, a chain transfer agent can be used 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 those that are usually used as chain transfer agents 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; Acids, phosphites, hypophosphites, hypophosphites, and hydrates thereof; sulfurous acid, hydrogen sulfite, dithionic acid, metabisulfite, and salts thereof (for example, sodium bisulfite) , Potassium hydrogen sulfite, sodium dithionite Um, potassium dithionite, sodium metabisulfite, metabisulfite potassium, etc.) and the like, include lower oxides and the like salts thereof. The said chain transfer agent may be used independently and may be used with the form of 2 or more types of mixtures.
The addition amount of the chain transfer agent is not particularly limited, but is preferably 1 to 20 g with respect to 1 mol of all monomer components. More preferably, it is 2 to 15 g. 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 pure polymer content may decrease.

Among the chain transfer agents, hypophosphite, sulfite, and / or bisulfite, because the dispersibility of the pigment (inorganic particles) in the resulting poly (meth) acrylic acid polymer aqueous solution is improved. Is preferably used. However, since the dispersibility of the pigment over time is improved, hypophosphite, sulfite, and bisulfite (total when used together) are used in an amount of 1 mol of all monomers. It is preferably 5.0 g or less, more preferably 4.5 g or less, still more preferably 4.0 g or less, and the lower limit of the amount used is 1 mol of all monomers. 1.0 g or more is preferable, and 1.5 g or more is more preferable.
When the use amount of hypophosphite, sulfite, and / or bisulfite exceeds the above upper limit with respect to 1 mol of all monomers, hypophosphite, sulfite, and Dispersion over time due to an increase in the amount of inorganic anions and / or an increase in bisulfite (hypophosphite, sulfite, and / or bisulfite not incorporated into the polymer ends) There is a possibility that the force may be reduced or the hue of the poly (meth) acrylic acid polymer may be deteriorated.

(Decomposition catalyst, reducing compound)
The method for producing a poly (meth) acrylic acid polymer of the present invention uses a polymerization initiator decomposition catalyst or a reducing compound (also called a reaction accelerator) in addition to the polymerization initiator (added to the polymerization system). May be.

Examples of the compound that acts as a decomposition catalyst or reducing compound for the polymerization initiator include heavy metal ions (or heavy metal salts). That is, the method for producing a polyacrylic acid polymer of the present invention may use (add to the polymerization system) heavy metal ions (or heavy metal salts) in addition to the polymerization initiator and the like.
In the present specification, the heavy metal ion means a metal having a specific gravity of 4 g / cm ³ or more.

As said heavy 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 ion is added to the reaction system by adding an aqueous solution or aqueous solution obtained by dissolving a heavy metal salt (heavy metal compound) 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. In the case of using these heavy metal salts, 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 ion is 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, when the heavy metal salt is supplied into the polymerization system, the heavy metal salt and the carboxyl group-containing compound are added. It is preferable to supply as an aqueous solution containing. When the heavy metal salt is supplied into the polymerization system, the effect of the heavy metal ion can be exhibited stably by supplying it as an aqueous solution containing the heavy metal salt and the carboxyl group-containing compound. 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 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 of the carboxyl group-containing compound with respect to 100 parts by mass of the heavy metal salt. More preferably, it is 10-80 mass parts.

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 carbon-carbon unsaturated double bond is preferable. Examples of such a compound include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and 2-methyleneglutaric acid. Etc. and their anhydrides.

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, 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, And heterocyclic amines such as carbazole 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, sulfoxyacid salts, benzenesulfinic acids and their substitutes, and homologues of cyclic sulfinic acids such as para-toluenesulfinic acid; octyl mercaptan, dodecyl mercaptan, mercaptoethanol, α-mercaptopropionic acid, thioglycol Mercapto compounds such as acid, thiopropionic acid, α-thiopropionic acid sodium sulfopropyl ester, α-thiopropionic acid sodium sulfoethyl ester; nitrogen-containing compounds such as hydrazine, β-hydroxyethylhydrazine, hydroxylamine; formaldehyde, aceto Aldehyde, propionaldehyde, n- butyraldehyde, isobutyraldehyde, aldehydes such as isovaleraldehyde; 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 a poly (meth) acrylic acid polymer of the present invention, in addition to the polymerization initiator, chain transfer agent, reaction accelerator, a pH adjuster, a buffering agent, and the like can be used as necessary. .

(Polymerization solution)
The poly (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 in which 50% by mass of water or water is used with respect to 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 30% by mass or less, more preferably 20% by mass or less, with respect to 100% by mass of the reaction liquid after completion of polymerization. More preferably, it is 10 mass% or less. It is particularly preferably 5% by mass or less, and most preferably 1% by mass or less.
When an organic solvent is used, a solvent removal step is required. Conditions such as pressure, temperature, and time in the solvent removal step can keep the resulting poly (meth) acrylic acid polymer aqueous solution low in color. Thus, it can be appropriately selected according to the type and amount of the organic solvent to be used. For example, the pressure at the time of solvent removal may be normal pressure, reduced pressure, or increased pressure, and the temperature is 30. -150 degreeC is preferable, 40-130 degreeC is more preferable, and 50-110 degreeC is especially preferable. The time required for solvent removal is preferably 10 hours or less, more preferably 5 hours or less, and particularly preferably 3 hours 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 more preferable, and 20-45 mass% is still more 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 method generally known as a polymerization method or a modified method thereof can be used unless otherwise specified.

The temperature during the polymerization is preferably 70 ° C. or higher, more preferably 75 to 110 ° C., and still more 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 resulting polymer, 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, dwelling, 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 (composition) of the present invention.

The content of the polymer of the present invention in the fiber treatment agent is preferably 1 to 100% by mass and more preferably 5 to 100% by mass with respect to 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 amount of 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 mass of the polymer of the present invention in terms of a pure component of the fiber treatment agent. It is preferable to use the composition mix | blended in the ratio of -100 mass parts 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, semisynthetic 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. That is, a pigment dispersant containing the poly (meth) acrylic acid polymer (aqueous solution) of the present invention is also one aspect of the present invention.
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 mass 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, a commonly used method can be appropriately referred to or combined, and for example, a method of performing primary dispersion and wet-grinding it can be mentioned. It is done. This method is suitable in that a high-concentration pigment slurry having a low viscosity and excellent dispersion stability can be obtained. Of course, the adjustment method of the pigment in the present invention is not limited to this wet pulverization method, and it is not limited to take an adjustment method without performing 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 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, an effect commensurate with the addition amount can be obtained, and this can be economically advantageous.

The pigment slurry in the present invention preferably has a solid 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. .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 knowledge generally known in the detergent field can be appropriately referred to. 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. Or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.
Examples of anionic surfactants 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 mono 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, and particularly preferably based on the total amount of the detergent composition. Is 25-40 mass%. If the blending ratio of the surfactant is too small, sufficient detergency may not be exhibited, and if the blending ratio of the surfactant is too large, the economy may be lowered.
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. Other detergent builders are not particularly limited, but include, for example, alkali builders such as carbonates, bicarbonates, silicates, tripolyphosphates, pyrophosphates, bow glass, nitrilotriacetate, ethylenediaminetetraacetate, citric acid. 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 exhibited, 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, still 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 still 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. 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, the salt composition is less precipitated and has an excellent cleaning effect. This effect is particularly pronounced when the detergent composition contains an anionic surfactant such as LAS.

[Inorganic particle slurry]
Moreover, the polymer of the present invention (polymer, polymer aqueous solution, polymer composition) can be used for the inorganic particle slurry. That is, the inorganic particle slurry containing the poly (meth) acrylic acid polymer of the present invention is also one aspect of the present invention.

<Poly (meth) acrylic acid polymer>
As the poly (meth) acrylic acid polymer contained in the inorganic particle slurry of the present invention, the same ones as described above can be used.
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 groups other than organic amine salt-type carboxyl groups The proportion of the salt is not particularly limited and can be the same as the above-described proportion, but the structure derived from (meth) acrylic acid (salt) and the organic amine (salt) contained in the inorganic particle slurry of the present invention. It is important that the molar ratio with the structure derived from) is 100: 10 to 100: 75. Preferably, it is 100: 15-100: 70, and it is more preferable that it is 100: 20-100: 65.

In addition, the structure derived from (meth) acrylic acid (salt) contained in the inorganic particle slurry means a structure derived from (meth) acrylic acid (salt) contained in the compound constituting the inorganic particle slurry. The structure derived from the organic amine (salt) contained in the slurry refers to a structure derived from the organic amine (salt) contained in the compound constituting the inorganic particle slurry.

Examples of the organic amine (salt) include those similar to those described above, and among them, the viscosity stability over time of the inorganic particle slurry is remarkably improved and a high pH can be maintained. The inorganic particle slurry preferably contains a structure derived from alkanolamine or a salt thereof.

The structure derived from the organic amine (salt) represents a structure neutralized with any acidic substance and present as an organic amine salt and / or a structure present as an organic amine. Examples of the structure neutralized with any acidic substance and existing as an organic amine salt include (i) a structure existing as a salt of the poly (meth) acrylic acid polymer, (ii) (meth) acrylic acid, etc. The structure which exists as a salt of the monomer or other acidic substance is illustrated.
Since the viscosity stability over time of the inorganic particle slurry tends to be improved, the inorganic particle slurry of the present invention is preferably in a form in which the amount of inorganic salt or the like is reduced as much as possible. Therefore, the organic amine (salt) The structure derived from is preferably a structure that exists as an organic amine salt of a carboxyl group of the poly (meth) acrylic acid polymer. Therefore, the ratio of the carboxyl group (organic amine salt type carboxyl group) neutralized with an organic amine to the carboxyl group of 100 mol% of the poly (meth) acrylic acid polymer is 10 to 75 mol%. Is more preferable, 15 to 70 mol% is more preferable, and 20 to 65 mol% is particularly preferable.

The poly (meth) acrylic acid polymer has a structure derived from all monomers contained in the poly (meth) acrylic acid polymer (that is, a structure derived from (meth) acrylic acid (salt) and other single quantities. It is preferable that the structure derived from (meth) acrylic acid (salt) is contained in an amount of 80% by mass or more in terms of the acid type with respect to 100% by mass with respect to the structure derived from the body. If it is 80 mass% or more, the viscosity stability with time of the inorganic particle slurry tends to be further improved. More preferably, it is 90 mass% or more.
Here, acid type conversion is as described above.

In the poly (meth) acrylic acid polymer, the structure derived from other monomers is 0 to 20% by mass relative to 100% by mass of the structure derived from all monomers contained in the poly (meth) acrylic acid polymer. It is preferable that it is 0-10 mass%.

Specifically, the weight average molecular weight of the poly (meth) acrylic acid polymer is preferably 3,000 to 50,000, more preferably 4,000 to 30,000, and still more preferably 5. , 20,000 to 20,000. If the value of the weight average molecular weight is too large, the viscosity of the inorganic particle slurry may not be sufficiently lowered. On the other hand, if the value of the weight average molecular weight is too small, the viscosity stability over time of the inorganic particle slurry may not be sufficiently improved.
In addition, as a value of the weight average molecular weight of the poly (meth) acrylic acid polymer, a value measured by a method described in Examples described later is adopted.

Further, the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the poly (meth) acrylic acid polymer is preferably 1.1 to 3.0, more preferably 1. .5 to 2.8, more preferably 1.8 to 2.6. Within this molecular weight distribution range, the viscosity of the inorganic particle slurry and the viscosity stability over time tend to be particularly improved.
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 a poly (meth) acrylic-acid type polymer.

<Inorganic particles>
The inorganic particle slurry of the present invention contains inorganic particles, but the inorganic particles used are not particularly limited, and examples thereof include kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, satin white, talc, Examples thereof include aluminum hydroxide and plastic pigment.

<Composition of inorganic particle slurry>
The inorganic particle slurry of the present invention preferably contains 70% by mass or more of inorganic particles with respect to 100% by mass of the inorganic particle slurry. If the inorganic particles contained in the inorganic particle slurry are less than 70% by mass, for example, when used as a paper coating pigment slurry, the paper productivity may be reduced. More preferably, it is 73 mass% or more, More preferably, it is 75 mass% or more. Most preferably, it is 78 mass% or more. Moreover, the upper limit of content of an inorganic particle is 85 mass%, for example.

The inorganic particle slurry of the present invention preferably contains 0.05 to 10% by mass (as acid type) of poly (meth) acrylic acid polymer with respect to 100% by mass of the inorganic particle slurry. More preferably, it is 0.1-5.0 mass%, More preferably, it is 0.15-1.0 mass%, Most preferably, it is 0.2-0.8 mass%.

In the inorganic particle slurry of the present invention, the compound derived from organic amine is such that the molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) falls within the above range. Contains in proportions.

The inorganic particle slurry of the present invention has a solid content concentration of 75% by mass or more. Preferably it is 78 mass% or more as solid content concentration, More preferably, it is 80 mass% or more, More preferably, it is 85 mass% or more. Moreover, the upper limit of the solid content concentration of the inorganic particle slurry is, for example, 90% by mass.
In addition, solid content concentration is a value measured by the measuring method mentioned later.

The inorganic particle slurry of the present invention usually contains water, and the water content in that case is preferably 25% by mass or less, more preferably 22% by mass or less, and still more preferably 20% by mass. Or less, and particularly preferably 15% by mass or less. Moreover, the minimum of content of the water in an inorganic particle slurry is 10 mass%, for example.

The average particle size of the inorganic particles contained in the inorganic particle slurry of the present invention is preferably 1.5 μm or less, more preferably 1.0 μm or less. In addition, the average particle diameter said here is a particle diameter measured with the laser particle size distribution meter which was used in the below-mentioned Example. Moreover, the inorganic particles contained in the inorganic particle slurry of the present invention contain 90 to 100% by mass of particles having a particle size of 2 μm or less with respect to 100% by mass of all inorganic particles, preferably 91 to 100% by mass is contained. If the particle diameter is in the above range, the gloss and whiteness of the paper will be good when the inorganic particle slurry of the present invention is used as, for example, a pigment dispersant for paper coating.

The inorganic particle slurry of the present invention may use condensed phosphoric acid and a salt thereof, phosphonic acid and a salt thereof, and polyvinyl alcohol as an organic solvent and other compounding agents as necessary.

The inorganic particle slurry of the present invention is characterized in that the concentration of inorganic anions containing sulfur atoms or phosphorus atoms is 100 to 400 ppm with respect to the inorganic particle slurry of the present invention. When the concentration of inorganic anions containing sulfur atoms or phosphorus atoms exceeds 400 ppm, the viscosity stability over time of the inorganic particle slurry tends to decrease. If the concentration of the inorganic anion containing a sulfur atom or phosphorus atom is set to less than 100 ppm, the combination of the initiator, the chain transfer agent and the solvent becomes expensive, which is not preferable.
Examples of the inorganic anion containing sulfur atom or phosphorus atom include sulfate ion, sulfite ion, phosphate ion, phosphite ion, hypophosphite ion and the like.

<Physical properties of inorganic particle slurry>
The viscosity of the inorganic particle slurry of the present invention is not particularly limited and varies greatly depending on the slurry concentration, but immediately after adjusting the solid content concentration of the inorganic particle slurry to 75% by mass, it is preferably 1000 mPa · s or less, More preferably, it is 900 mPa · s or less.
The viscosity of the inorganic particle slurry was measured using a B-type viscometer. The value measured at 4, 60 rpm for 5 minutes.

[Production method of inorganic particle slurry]
The method for producing an inorganic particle slurry of the present invention comprises (i) a poly (meth) acrylic acid polymer aqueous solution containing a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt), and A method for producing an essential step of mixing inorganic particles, (ii) a poly (meth) acrylic acid polymer aqueous solution containing a poly (meth) acrylic acid polymer, an organic amine (salt), and inorganic particles. It is one of the methods which manufacture by making the process of mixing essential. In the case of the production method (ii), two of the three components may be mixed in advance and then mixed with the remaining one, or three may be mixed simultaneously.
In addition, the manufacturing method of the inorganic particle slurry of this invention may include the process of mixing a solvent and another compounding agent, as long as the said mixing process is included.

<Poly (meth) acrylic acid polymer aqueous solution>
As said poly (meth) acrylic-acid type polymer aqueous solution, the thing similar to the polymer aqueous solution of this invention mentioned above can be used.
The poly (meth) acrylic acid polymer aqueous solution has a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt) contained in the poly (meth) acrylic acid polymer aqueous solution. The molar ratio is preferably 100: 10 to 100: 75. Separately adding a poly (meth) acrylic acid polymer or organic amine (salt) to form a mole of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) in the inorganic particle slurry Although it is possible to adjust the ratio to be in the above range, it is derived from (meth) acrylic acid (salt) contained in the poly (meth) acrylic acid polymer aqueous solution in terms of production efficiency of the inorganic particle slurry. The molar ratio between the structure to be formed and the structure derived from the organic amine (salt) is preferably set in the above range. By setting to such a range, it becomes possible to remarkably express the stability of the viscosity of the inorganic particle slurry over time. More preferably, it is 100: 15-100: 70, and it is still more preferable that it is 100: 20-100: 65.

When the poly (meth) acrylic acid polymer aqueous solution includes a structure derived from an organic amine (salt), a structure derived from an organic amine (salt) contained in the poly (meth) acrylic acid polymer aqueous solution (meta ) Aspects of the structure derived from acrylic acid (salt) are the same as those in the inorganic fine particle slurry unless otherwise specified.
The structure derived from the organic amine (salt) contained in the poly (meth) acrylic acid polymer aqueous solution includes, for example, (i) an aqueous solution containing an acid type and / or a partially neutralized polyacrylic acid polymer. The structure contained in the carboxyl group salt neutralized with organic amine formed by adding organic amine to (ii) monomers such as (meth) acrylic acid previously neutralized with organic amine Examples include a structure formed by polymerization of an organic amine salt and (iii) a structure existing as an unreacted organic amine.
Since the viscosity stability over time of the inorganic particle slurry tends to be improved, the poly (meth) acrylic acid polymer aqueous solution is preferably in a form in which the amount of inorganic salt or the like is reduced as much as possible, and therefore organic The structure derived from an amine (salt) is preferably a structure that exists as an organic amine salt of a carboxyl group. The ratio of the carboxyl group neutralized with the organic amine with respect to 100 mol% of the carboxyl group of the poly (meth) acrylic acid polymer is the same as that in the inorganic particle slurry.

<Method for producing poly (meth) acrylic acid polymer (aqueous solution)>
As a method for producing the poly (meth) acrylic acid polymer (aqueous solution), it can be produced by the same method as the method for producing the poly (meth) acrylic acid polymer (aqueous solution) of the present invention described above. .

<Manufacturing method of other inorganic particle slurry>
As the method for producing the inorganic particle slurry of the present invention, the production method usually used for producing the inorganic particle slurry can be referred to as appropriate, or it can be carried out by combining, but typically, the primary dispersion And a method of wet pulverizing it. This method is suitable in that a high-concentration pigment slurry having a low viscosity and excellent dispersion stability can be obtained. Of course, the inorganic particle slurry adjusting method in the present invention is not limited to this wet pulverization method, and it is not limited at all to adopt an adjustment method in which the wet pulverization treatment is not performed. In the method for preparing the inorganic particle slurry, the primary dispersion method is not particularly limited, but is preferably mixed with a mixer, for example, a shear such as a high-speed disper, a homomixer, a ball mill, a coreless mixer, and a stirring disper. It is preferable to use one having a high strength.

The method for producing fine inorganic particles according to the present invention comprises (i) a poly (meth) acrylic acid polymer aqueous solution containing a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt), and After mixing the inorganic particles, or (ii) after mixing the poly (meth) acrylic acid polymer aqueous solution containing the poly (meth) acrylic acid polymer, the organic amine (salt), and the inorganic particles, It is preferable to include a step of wet-grinding the inorganic particles. In this case, the particle size of the inorganic particles contained in the inorganic particle slurry can be efficiently set within a desired range. In such a case, the poly (meth) acrylic acid polymer (aqueous solution) of the present invention also serves as a grinding aid.

[Use of inorganic particle slurry]
The inorganic particle slurry of the present invention can be used for paper coating, paper processing, ceramic molding, fiber treatment, emulsion coating and the like.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.
In addition, the weight average molecular weight, number average molecular weight, unreacted monomer quantification, polymer aqueous solution and solid content of polymer composition, and effective component value of the polymer aqueous solution of the polymer of the present invention are as follows. It was measured.

<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, after neutralizing the carboxylic acid in the polymer completely with 1N NaOH aqueous solution, 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)>
The weight average molecular weight and number average molecular weight of the polymer were measured using GPC (gel permeation chromatography) under the following conditions.
Apparatus: L-7000 series manufactured by Hitachi, Ltd. Detector: HITACHI RI Detector L-2490
Column: TSK-GEL G3000PWXL manufactured by Tosoh Corporation
Column temperature: 40 ° C
Flow rate: 0.5 mL / min
Calibration curve: POLY SODIUM ACRYLATE STANDARD
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 KK
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: 762 Interface manufactured by Metrohm
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.
When the polymer aqueous solution obtained in the following Example was analyzed, the sulfate ion derived from sodium persulfate and the hypophosphite ion derived from sodium hypophosphite were detected.

<Measurement of solid content concentration of slurry>
In an air atmosphere, the inorganic particle slurry was left to dry in an oven heated to 150 ° C. for 0.5 hours. The solid content (%) was calculated from the weight change before and after drying.

<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 is 10%. A mixture prepared by mixing 8 parts by mass of an aqueous polymer solution (diluted or concentrated with water, etc.) and 46 parts by mass of pure water and 500 parts by mass of 2 mm ceramic beads were added little by little. After all the charging, the number of rotations was increased to 1000 rpm at once, and after confirming the state of the beads, the number of rotations was further increased to 1500 rpm. 40 minutes after 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 Hitachi, Ltd.
The viscosity of the slurry was measured with a B-type viscometer using a rotor No. 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), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out under the following polymerization prescription and conditions using a reaction apparatus having a reflux cooling apparatus and a neutralizer. First, 362 parts by mass of ion-exchanged water was charged. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket at room temperature.
Next, 925 parts by mass of an 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”) for 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, 45% by weight sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) is 17 parts by weight, 20 minutes, and then 70 parts by weight for 160 minutes, each at a two-stage feed rate. It was dripped from the tip nozzle through the supply path. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP.
Thereafter, 600 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 70%) is dropped into the polymerization kettle from the tip nozzle through the supply path to neutralize the polymer, followed by monoethanolamine. 175 parts by mass (hereinafter also referred to as “MEA”) (AA neutralization rate of 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path to neutralize the polymer. As described above, an aqueous sodium polyacrylate / monoethanolamine salt solution (1) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (1)) had a solid content value of 52.7% and an active ingredient value of 44.7%. The aqueous polymer solution (1) had a Brookfield viscosity of 850 mPa · s, a weight average molecular weight (Mw) of 5200, and a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 2.15. 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 (1) was 5900 ppm.
The polymerization prescription is shown in Table 1, and the analysis results are shown in Table 2. In Table 2, 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 heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity after 1 hour of pulverization was 950 mPa · s, and the slurry viscosity after 1 week was 3380 mPa · s.

<Example 2>
A sodium polyacrylate / monoethanolamine salt 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 solid content value in the obtained aqueous solution (referred to as polymer aqueous solution (2)) was 59.0%, and the active ingredient value was 45.4%. In addition, the Brookfield viscosity of the aqueous polymer solution (2) was 990 mPa · s, the weight average molecular weight (Mw) was 5400, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.14. The polymerization prescription is shown in Table 1, and the analysis results of the 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 630 mPa · s, and the slurry viscosity after one week was 2090 mPa · s.

<Example 3>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out under the following polymerization prescription and conditions using a reaction apparatus (see FIG. 1) having an external circulation cooling apparatus (for the neutralizing agent) and an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus). 515 parts by mass of ion-exchanged water and 16 parts by mass of a 45% by mass sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) were charged. Thereafter, the temperature of the aqueous solution was raised to 82 ° C. with an external jacket at room temperature while stirring the aqueous solution in the polymerization kettle.
Next, 900 parts by mass of 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”), 67% by mass of 45% SHP, and 15% by mass sodium persulfate aqueous solution (hereinafter also referred to as “15% NaPS”). ) 67 parts by weight from the tip nozzles through separate supply paths, 80% AA and 45% SHP are added dropwise for 150 minutes, and 15% NaPS is added dropwise simultaneously with 80% AA for 155 minutes (ie , Until 5 minutes after the completion of dropping 80% AA). The dropping of each component was continuously performed at a constant dropping rate.
Thereafter, 583 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 70%) is dropped into the polymerization kettle from the tip nozzle through the supply path to neutralize the polymer, followed by monoethanolamine. 171 parts by mass (AA neutralization rate of 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path to neutralize the polymer. During the neutralization of the polymer, the reaction solution was cooled by a heat removal device while always circulating the reaction solution externally.
As described above, a sodium polyacrylate / monoethanolamine salt aqueous solution (3) was obtained. The obtained aqueous solution (3) (referred to as polymer aqueous solution (3)) had a solid content value of 52.4% and an active ingredient value of 40.2%. The Brookfield viscosity of the aqueous polymer solution (3) was 800 mPa · s, the weight average molecular weight (Mw) was 5500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.15. 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-described method, the slurry viscosity immediately after pulverization was 1000 mPa · s, and the slurry viscosity after 1 week was 3450 mPa · s.

<Example 4>
A sodium polyacrylate aqueous solution (4) was obtained in the same manner as in Example 3 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 56.9% and an active ingredient value of 40.3%. The Brookfield viscosity of the aqueous polymer solution (4) was 950 mPa · s, the weight average molecular weight (Mw) was 5700, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.18. 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 890 mPa · s, and the slurry viscosity after one week was 2210 mPa · s.

<Comparative Example 1>
A sodium polyacrylate aqueous solution (5) 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 (5)) had a solid content value of 46.6% and an active ingredient value of 44.5%. The Brookfield viscosity of the aqueous polymer solution (5) was 900 mPa · s, the weight average molecular weight (Mw) was 5900, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.30. 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 1800 mPa · s, and the slurry viscosity after one week was 4700 mPa · s.

<Comparative example 2>
A sodium polyacrylate aqueous solution (6) was obtained in the same manner as in Example 3, except that the polymerization conditions were changed to those shown in Table 1. The obtained aqueous solution (referred to as polymer aqueous solution (6)) had a solid content value of 43.3% and an active ingredient value of 41.3%. The aqueous polymer solution (6) had a Brookfield viscosity of 780 mPa · s, a weight average molecular weight (Mw) of 5500, and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.20. 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 1400 mPa · s, and the slurry viscosity after 1 week was 3800 mPa · s.

The polymerization prescription in Examples 1-4 and Comparative Examples 1-2 is summarized in Table 1, and the measurement results and evaluation results of the polymers are summarized in Table 2.

From the results shown in Table 2, it has been clarified that the polymer of the present invention has a good initial dispersion force and a temporal dispersion force as compared with the conventional polymer.

<Example 5>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was performed under the following polymerization prescription and conditions using a reaction apparatus having a neutralizing agent) and an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus). First, 362 parts by mass of ion-exchanged water was charged. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket under normal pressure.
Next, 925 parts by mass of an 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”) for 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, 45% by weight sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) is 17 parts by weight, 20 minutes, and then 70 parts by weight for 160 minutes, each at a two-stage feed rate. It was dripped from the tip nozzle through the supply path. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP. After completion of the dropwise addition of 15% NaPS, the solution was aged for 30 minutes while maintaining the refluxed state of the aqueous solution. The temperature of the aqueous solution at this time showed 103 degreeC.
Thereafter, the temperature of the aqueous solution is cooled to 65 ° C. using an external cooling circulation device, and the aqueous solution temperature is maintained at 65 to 80 ° C. 70%) was dropped from the tip nozzle into the polymerization vessel through the supply path over 60 minutes to neutralize the polymer (step N1), followed by monoethanolamine (hereinafter also referred to as “MEA”). 175 parts by mass (AA neutralization rate of 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path over 30 minutes to neutralize the polymer (step N2). The total time required for the steps N1 and N2 was 90 minutes. As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (7) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (7)) had a solid content value of 52.7% and an active ingredient value of 44.7%. The Brookfield viscosity of the aqueous polymer solution (7) was 850 mPa · s, the weight average molecular weight (Mw) was 5200, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.15. 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 (7) was 5900 ppm.
Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (7) was 60, and APHA after one-month progress was 140 at room temperature (25 degreeC). The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4. In Table 3, 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 heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity after 1 hour of pulverization was 950 mPa · s, and the slurry viscosity after 1 week was 3380 mPa · s.

<Example 6>
A sodium polyacrylate / monoethanolamine aqueous solution (8) was obtained in the same manner as in Example 5 except that the polymerization conditions were changed to those described in Table 3. The solid content value in the obtained aqueous solution (referred to as polymer aqueous solution (8)) was 59.0%, and the active ingredient value was 44.7%. The aqueous polymer solution (8) had a Brookfield viscosity of 990 mPa · s, a weight average molecular weight (Mw) of 5400, and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.14. 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 (8) was 6100 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (8) was 70, and APHA after one-month progress was 150 at room temperature (25 degreeC).
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 630 mPa · s, and the slurry viscosity after one week was 2090 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Example 7>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was performed under the following polymerization prescription and conditions using a reaction apparatus having a neutralizing agent) and an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus). 515 parts by mass of ion-exchanged water and 16 parts by mass of a 45% by mass sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) were charged. Thereafter, the temperature of the aqueous solution was raised to 82 ° C. with an external jacket at room temperature while stirring the aqueous solution in the polymerization kettle.
Next, 900 parts by mass of 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”), 67% by mass of 45% SHP, and 15% by mass sodium persulfate aqueous solution (hereinafter also referred to as “15% NaPS”). ) 67 parts by weight from the tip nozzles through separate supply paths, 80% AA and 45% SHP are added dropwise for 150 minutes, and 15% NaPS is added dropwise simultaneously with 80% AA for 155 minutes (ie , Until 5 minutes after the completion of dropping 80% AA). The dropping of each component was continuously performed at a constant dropping rate. After completion of the dropwise addition of 15% NaPS, aging was performed for 30 minutes while maintaining the reflux of the aqueous solution.
Thereafter, using an external circulation cooling device, the temperature of the aqueous solution is cooled to 65 ° C., and the temperature of the aqueous solution is maintained at 65 to 80 ° C. 70%) was dropped from the tip nozzle into the polymerization kettle through the supply path over 60 minutes to neutralize the polymer (step N1), followed by 171 parts by mass of monoethanolamine (AA neutralization rate 28). %) Was added dropwise to the polymerization kettle from the tip nozzle through another supply path over 30 minutes to neutralize the polymer (step N2). The total time required for the steps N1 and N2 was 90 minutes.
As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (9) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (9)) had a solid content value of 52.4% and an active ingredient value of 40.2%. The Brookfield viscosity of the aqueous polymer solution (9) was 800 mPa · s, the weight average molecular weight (Mw) was 5500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.15. The total concentration of inorganic anions including sulfur atoms or phosphorus atoms (mainly sulfate ions and hypophosphite ions were detected) in the aqueous polymer solution (9) was 6400 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (9) was 60, and APHA after one-month progress was 140 at room temperature (25 degreeC).
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above method, the slurry viscosity immediately after pulverization was 1000 mPa · s, and the slurry viscosity after 1 week was 3450 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Example 8>
A sodium polyacrylate aqueous solution (10) was obtained in the same manner as in Example 7 except that the polymerization conditions were changed to those described in Table 3. The obtained aqueous solution (referred to as polymer aqueous solution (10)) had a solid content value of 56.9% and an active ingredient value of 40.3%. The Brookfield viscosity of the aqueous polymer solution (10) was 950 mPa · s, the weight average molecular weight (Mw) was 5700, and the weight 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 aqueous polymer solution (10) was 6500 ppm. The polymer aqueous solution (10) had a solid hue (APHA) immediately after production of 75, and an APHA of 150 after one month at room temperature (25 ° C.).
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 890 mPa · s, and the slurry viscosity after one week was 2210 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Example 9>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out using a reaction apparatus having a neutralizing agent), an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus), and a solvent distillation apparatus under the following polymerization prescription and conditions. 350 parts by mass of ion-exchanged water and 200 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, aging was performed for 30 minutes while maintaining the reflux of the mixed solution.
After completion of aging, the mixture of IPA and water was distilled off at a temperature of 80 to 103 ° C. over 120 minutes until the IPA in the polymerization kettle disappeared (step D), and then 220 parts by mass of ion-exchanged water was put into the polymerization kettle. Thus, the temperature of the aqueous solution was adjusted to 70 ° C. Using an external circulation cooling device, the temperature of the aqueous solution is maintained at 70 to 85 ° C., and 583 parts by mass of a 48 mass% sodium hydroxide aqueous solution (AA neutralization rate of 70%) is supplied from the tip nozzle through the supply path. After dripping in the polymerization kettle over 60 minutes to partially neutralize the polymer (step N1), 171 parts by mass of monoethanolamine (AA neutralization rate of 28%) was then added to the tip through another supply path. The solution was dropped from the nozzle into the polymerization kettle over 30 minutes to neutralize the polymer (step N2). The total time required for the steps N1 and N2 was 90 minutes. As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (11) was obtained.
The obtained aqueous solution (referred to as polymer aqueous solution (11)) had a solid content value of 52.5% and an active ingredient value of 40.3%. The Brookfield viscosity of the aqueous polymer solution (11) was 600 mPa · s, the weight average molecular weight (Mw) was 4500, and the weight 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 (11) (mainly sulfate ions and hypophosphite ions were detected) was 6500 ppm. Moreover, the hue (APHA) in the solid immediately after manufacture of polymer aqueous solution (11) was 70, and APHA after one-month progress was 150 at room temperature (25 degreeC).
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 1 week was 3400 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Example 10>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out using a reaction apparatus having a neutralizing agent), an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus), and a solvent distillation apparatus under the following polymerization prescription and conditions. 350 parts by mass of ion-exchanged water and 200 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, aging was performed for 30 minutes while maintaining the reflux of the mixed solution.
After completion of the aging, the external solution is cooled until the temperature of the mixed solution reaches 65 ° C., and the temperature of the mixed solution is maintained at 65 to 80 ° C. Part (AA neutralization rate of 70%) is dropped over 60 minutes from the tip nozzle into the polymerization vessel through the supply path to partially neutralize the polymer (step N1), and then monoethanolamine 171 A part by mass (AA neutralization rate of 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path over 30 minutes to neutralize the polymer (step N2). The total time required for the steps N1 and N2 was 90 minutes.
Next, after the IPA and water mixture was distilled off at 80 to 103 ° C. for 120 minutes until the IPA in the polymerization kettle disappeared (step D), 220 parts by mass of ion-exchanged water was put into the polymerization kettle. A sodium polyacrylate / monoethanolamine salt aqueous solution (12) was obtained.
The obtained aqueous solution (referred to as polymer aqueous solution (12)) had a solid content value of 52.6% and an active ingredient value of 40.4%. The Brookfield viscosity of the aqueous polymer solution (12) was 620 mPa · s, the weight average molecular weight (Mw) was 4600, and the weight 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 (12) (mainly sulfate ions and hypophosphite ions were detected) was 6400 ppm. Moreover, the hue (APHA) in solid of polymer aqueous solution (12) was 90, and APHA after one-month progress was 160 at room temperature (25 degreeC).
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 920 mPa · s, and the slurry viscosity after 1 week was 3450 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Comparative Example 3>
A sodium polyacrylate aqueous solution (13) was obtained in the same manner as in Example 5, except that the polymerization conditions were changed to those shown in Table 3. The obtained aqueous solution (referred to as polymer aqueous solution (13)) had a solid content value of 46.6% and an active ingredient value of 44.5%. The Brookfield viscosity of the aqueous polymer solution (13) was 900 mPa · s, the weight average molecular weight (Mw) was 5900, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.30. Further, 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 (13) was 5800 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (13) was 60, and APHA after one-month progress was 130 at room temperature (25 degreeC).
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 1800 mPa · s, and the slurry viscosity after one week was 4700 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Comparative Example 4>
A sodium polyacrylate aqueous solution (14) was obtained in the same manner as in Example 7 except that the polymerization conditions were changed to those shown in Table 3. The obtained aqueous solution (referred to as polymer aqueous solution (14)) had a solid content value of 43.3% and an active ingredient value of 41.3%. The Brookfield viscosity of the aqueous polymer solution (14) was 680 mPa · s, the weight average molecular weight (Mw) was 5,500, and the weight 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 aqueous polymer solution (14) was 6200 ppm. Moreover, the hue (APHA) in the solid immediately after manufacture of polymer aqueous solution (14) was 70, and APHA after one-month progress was 140 at room temperature (25 degreeC).
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 1700 mPa · s, and the slurry viscosity after 1 week was 4800 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Comparative Example 5>
A sodium polyacrylate aqueous solution (15) was obtained in the same manner as in Example 9, except that the polymerization conditions were changed to those shown in Table 3. The obtained aqueous solution (referred to as polymer aqueous solution (15)) had a solid content value of 43.1% and an active ingredient value of 41.1%. The Brookfield viscosity of the aqueous polymer solution (15) was 650 mPa · s, the weight average molecular weight (Mw) was 4500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.20. The total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the aqueous polymer solution (15) (mainly sulfate ions and hypophosphite ions were detected) was 6400 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (15) was 75, and APHA after one-month progress was 160 at room temperature (25 degreeC).
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 1400 mPa · s, and the slurry viscosity after 1 week was 4200 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Comparative Example 6>
A sodium polyacrylate / monoethanolamine salt aqueous solution (16) was obtained in the same manner as in Example 5 except that the polymerization conditions were changed to those shown in Table 3. In addition, at the time of aging and neutralization of the polymerization liquid (step N1 and step N2), the aqueous solution was kept in a reflux state, and the temperature of the aqueous solution at this time was 103 ° C. The obtained aqueous solution (referred to as polymer aqueous solution (16)) had a solid content value of 53.2% and an active ingredient value of 44.9%. The aqueous polymer solution (16) had a Brookfield viscosity of 900 mPa · s, a weight average molecular weight (Mw) of 5500, and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.17. Further, the total concentration of inorganic anions containing sulfur atoms or phosphorus atoms in the polymer aqueous solution (16) (mainly sulfate ions and hypophosphite ions were detected) was 5500 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (16) was 80, and APHA after one-month progress was 250 at room temperature (25 degreeC).
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 3500 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

<Comparative Example 7>
A sodium polyacrylate / monoethanolamine salt aqueous solution (17) was obtained in the same manner as in Example 6 except that the polymerization conditions were changed to those shown in Table 3. In addition, at the time of aging and neutralization of the polymerization liquid (step N1 and step N2), the aqueous solution was kept in a reflux state, and the temperature of the aqueous solution at this time was 103 ° C. The obtained aqueous solution (referred to as polymer aqueous solution (17)) had a solid content value of 59.2% and an active ingredient value of 44.9%. The Brookfield viscosity of the aqueous polymer solution (17) was 1100 mPa · s, the weight average molecular weight (Mw) was 5,500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.19. 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 (17) was 5600 ppm. Moreover, the hue (APHA) in the solid state immediately after manufacture of polymer aqueous solution (17) was 80, and APHA after one-month progress was 300 at room temperature (25 degreeC).
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 800 mPa · s, and the slurry viscosity after 1 week was 2700 mPa · s. The polymerization results and the analysis results of the polymer are shown in Table 3, and the evaluation results are shown in Table 4.

Table 3 summarizes the polymerization formulations and polymer analysis results in Examples 5 to 10 and Comparative Examples 3 to 7, and Table 4 summarizes the evaluation results. In Table 4, in addition to the evaluation results, “a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt) contained in an aqueous solution containing a poly (meth) acrylic acid polymer” The "molar ratio" is summarized.

From the results shown in Table 4, the polymer of the present invention has a good initial dispersive force and a dispersive force over time as compared with the conventional polymer, and (i) the acid type and / or A step of neutralizing an aqueous solution containing a partially neutralized poly (meth) acrylic acid polymer with an alkali metal salt; and (ii) an acid type and / or a partially neutralized poly (meth) acrylic acid polymer. It has been clarified that by producing an aqueous solution containing a solution neutralized with an organic amine, it has a good color tone over time.

<Example 11>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out under the following polymerization prescription and conditions using a reaction apparatus having a reflux cooling apparatus and a neutralizer. First, 362 parts by mass of ion-exchanged water was charged. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket at room temperature.
Next, 925 parts by mass of an 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”) for 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, 45% by weight sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) is 17 parts by weight, 20 minutes, and then 70 parts by weight for 160 minutes, each at a two-stage feed rate. It was dripped from the tip nozzle through the supply path. The dropping of each component was continuously performed at a constant dropping rate except for 45% SHP.
Thereafter, 600 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 70%) is dropped into the polymerization kettle from the tip nozzle through the supply path to neutralize the polymer, followed by monoethanolamine. 175 parts by mass (hereinafter also referred to as “MEA”) (AA neutralization rate of 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 (18) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (18)) had a solid content value of 52.7% and an active ingredient value of 44.7%. The aqueous polymer solution (18) had a Brookfield viscosity of 850 mPa · s, a weight average molecular weight (Mw) of 5200, and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.15. 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 (18) was 5900 ppm.
According to the evaluation example, the aqueous polymer solution (18) was used to obtain the inorganic particle slurry (heavy calcium carbonate slurry (18)) of the present invention. The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (18) was 90.1% by mass, and the solid content concentration was 77.6% by mass.
When the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity after 1 hour of pulverization was 950 mPa · s, and the slurry viscosity after 1 week was 3380 mPa · s.
Table 5 shows the polymerization formulation and the analysis results of the polymer, and Table 6 shows the evaluation results.

<Example 12>
A sodium polyacrylate / monoethanolamine salt aqueous solution (19) was obtained in the same manner as in Example 11 except that the polymerization conditions were changed to those shown in Table 5. The solid content value in the obtained aqueous solution (referred to as polymer aqueous solution (19)) was 59.0%, and the active ingredient value was 45.4%. The aqueous polymer solution (19) had a Brookfield viscosity of 990 mPa · s, a weight average molecular weight (Mw) of 5400, and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.14.
According to the evaluation example, the inorganic particle slurry (heavy calcium carbonate slurry (19)) of the present invention was obtained using the polymer aqueous solution (19). The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (19) was 90.2% by mass, and the solid content concentration was 77.4% by mass.
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 630 mPa · s, and the slurry viscosity after one week was 2090 mPa · s.
Table 5 shows the polymerization formulation and the analysis results of the polymer, and Table 6 shows the evaluation results.

<Example 13>
Batch type polymerization kettle (manufactured by SUS, volume 5 m ³ ), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and Polymerization was carried out using the reaction apparatus (see FIG. 1) having an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus) (see FIG. 1) and the following polymerization recipe and conditions. 515 parts by mass of ion-exchanged water and 16 parts by mass of a 45% by mass sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) were charged. Thereafter, the temperature of the aqueous solution was raised to 82 ° C. with an external jacket at room temperature while stirring the aqueous solution in the polymerization kettle.
Next, 900 parts by mass of an 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”), 67% by mass of 45% SHP, and a 15% by mass sodium persulfate aqueous solution (hereinafter also referred to as “15% NaPS”). ) 67 parts by mass from the tip nozzles through separate supply paths, 80% AA and 45% SHP are added dropwise for 150 minutes and 15% NaPS is started to drop simultaneously with 80% AA for 155 minutes (ie , Until 5 minutes after the completion of dropping 80% AA). The dropping of each component was continuously performed at a constant dropping rate.
Thereafter, 583 parts by mass of a 48% by mass aqueous sodium hydroxide solution (AA neutralization rate of 70%) is dropped into the polymerization kettle from the tip nozzle through the supply path to neutralize the polymer, followed by monoethanolamine. 171 parts by mass (AA neutralization rate of 28%) was dropped into the polymerization kettle from the tip nozzle through another supply path to neutralize the polymer. During the neutralization of the polymer, the reaction solution was cooled by a heat removal device while always circulating the reaction solution externally.
As described above, an aqueous solution of sodium polyacrylate / monoethanolamine salt (20) was obtained. The obtained aqueous solution (referred to as polymer aqueous solution (20)) had a solid content value of 52.4% and an active ingredient value of 40.2%. The Brookfield viscosity of the aqueous polymer solution (20) was 800 mPa · s, the weight average molecular weight (Mw) was 5500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.15.
According to the evaluation example, the polymer aqueous solution (20) was used to obtain the inorganic particle slurry (heavy calcium carbonate slurry (20)) of the present invention. The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (20) was 90.3% by mass, and the solid content concentration was 77.5% by mass.
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 3450 mPa · s.
Table 5 shows the polymerization formulation and the analysis results of the polymer, and Table 6 shows the evaluation results.

<Example 14>
A sodium polyacrylate aqueous solution (21) was obtained in the same manner as in Example 13 except that the polymerization conditions were changed to those shown in Table 5. The obtained aqueous solution (referred to as polymer aqueous solution (21)) had a solid content value of 56.9% and an active ingredient value of 40.3%. The Brookfield viscosity of the aqueous polymer solution (21) was 950 mPa · s, the weight average molecular weight (Mw) was 5700, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.18.
According to the evaluation example, the aqueous polymer solution (21) was used to obtain an inorganic particle slurry (heavy calcium carbonate slurry (21)) of the present invention. The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (21) was 90.5% by mass, and the solid content concentration was 77.7% by mass.
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 890 mPa · s, and the slurry viscosity after one week was 2210 mPa · s.
The polymerization results and the analysis results of the polymer are shown in Table 5, and the evaluation results are shown in Table 6.

<Comparative Example 8>
A sodium polyacrylate aqueous solution (22) was obtained in the same manner as in Example 11 except that the polymerization conditions were changed to those shown in Table 5. The obtained aqueous solution (referred to as polymer aqueous solution (22)) had a solid content value of 46.6% and an active ingredient value of 44.5%. The Brookfield viscosity of the aqueous polymer solution (22) was 900 mPa · s, the weight average molecular weight (Mw) was 5900, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.30.
According to the evaluation example, the aqueous polymer particle (22) was used to obtain the inorganic particle slurry (heavy calcium carbonate slurry (22)) of the present invention. The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (22) was 90.2 mass%, and the solid content concentration was 77.3 mass%.
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 1800 mPa · s, and the slurry viscosity after one week was 4700 mPa · s.
The polymerization results and the analysis results of the polymer are shown in Table 5, and the evaluation results are shown in Table 6.

<Comparative Example 9>
A sodium polyacrylate aqueous solution (23) was obtained in the same manner as in Example 13 except that the polymerization conditions were changed to those shown in Table 5. The obtained aqueous solution (referred to as polymer aqueous solution (23)) had a solid content value of 43.3% and an active ingredient value of 41.3%. The Brookfield viscosity of the aqueous polymer solution (23) was 780 mPa · s, the weight average molecular weight (Mw) was 5,500, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.20.
According to the evaluation example, an aqueous polymer solution (23) was used to obtain an inorganic particle slurry (heavy calcium carbonate slurry (23)) of the present invention. The proportion of inorganic particles of 2 μm or less in the heavy calcium carbonate slurry (23) was 90.1% by mass, and the solid content concentration was 77.6% by mass.
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 1400 mPa · s, and the slurry viscosity after 1 week was 3800 mPa · s.
The polymerization results and the analysis results of the polymer are shown in Table 5, and the evaluation results are shown in Table 6.

In Tables 11 and 14, the analysis results of the polymerization recipes and polymers in Examples 11 to 14 and Comparative Examples 8 to 9 are summarized in Table 5, and the evaluation results are summarized in Table 6.
In Table 5, “molar ratio of structure” means “a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt) contained in an aqueous poly (meth) acrylic acid polymer solution” The molar ratio (structure derived from (meth) acrylic acid (salt) / structure derived from organic amine (salt)) ". In Table 5, the density | concentration of the inorganic anion containing the sulfur atom or phosphorus atom contained in polymer aqueous solution was described as ion concentration total.
In Table 6, “Molar ratio of structure” means “molar ratio of a structure derived from (meth) acrylic acid (salt) and a structure derived from organic amine (salt) contained in the inorganic particle slurry (( Structure derived from (meth) acrylic acid (salt) / structure derived from organic amine (salt) ”. In Table 6, the density | concentration of the inorganic anion containing the sulfur atom or phosphorus atom contained in an inorganic particle slurry was described as ion concentration total.

From the results shown in Table 6, it has been clarified that the inorganic particle slurry of the present invention has a good initial viscosity and viscosity stability over time as compared with the conventional inorganic particle slurry.

Claims (3)

An inorganic particle dispersant containing an aqueous solution containing a poly (meth) acrylic acid polymer,
The structure derived from (meth) acrylic acid (salt) is contained in an amount of 80% by mass or more in terms of the acid type with respect to 100% by mass of the structure derived from all monomers contained in the poly (meth) acrylic acid polymer,
At least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized with an organic amine;
The poly (meth) acrylic acid polymer uses 0.1 g or more and 1.9 g or less of persulfate with respect to 1 mol of all monomers used for the production of the poly (meth) acrylic acid polymer. The amount of the persulfate-derived structural site corresponding to the polymer terminal is 1.0 g or more with respect to 1 mol of all monomers used for the production of the poly (meth) acrylic acid polymer. A chain transfer agent-derived structural site corresponding to the amount of chain transfer agent of 5.0 g or less is used at the polymer end, and the chain transfer agent comprises hypophosphite, sulfite, and bisulfite. The weight average molecular weight is 3,000 to 50,000, the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 1.1 to 3.0,
The structure formed by radical polymerization of (meth) acrylic acid (salt) contained in the aqueous solution, wherein —CH ₂ CR (COOM) — (R represents a hydrogen atom or a methyl group, M represents , Represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt.), And the number of moles of a structure formed by reaction of an organic amine (salt) added to an aqueous solution. The molar ratio with the total number of moles of organic amine (salt) present unreacted is 100: 15 to 100: 70 ,
The concentration of inorganic anions containing sulfur atoms or phosphorus atoms contained in the aqueous solution is 1000 to 10,000 ppm with respect to the aqueous solution,
The aqueous solution containing the poly (meth) acrylic acid polymer contains 50 to 500% by mass of a solvent essential to water with respect to 100% by mass of the poly (meth) acrylic acid polymer, and APHA is 200 or less. An inorganic particle dispersant characterized by the above. 2. The inorganic particle dispersant according to claim 1, wherein the solid content concentration is 35 to 70 mass%, and the viscosity at 25 ° C. is 400 to 2000 mPa · s. The inorganic particle dispersant according to claim 1 or 2, wherein the pH is 2.5 to 9.0.