KR101800918B1 - Dispersant for calcium carbonate and method for producing same - Google Patents

Abstract

The present invention relates to a dispersant for calcium carbonate, which has a low initial viscosity of a calcium carbonate slurry obtained by wet pulverization and in which a remarkable increase in viscosity with time is suppressed, and a production method thereof. The dispersant for calcium carbonate of the present invention is obtained by reacting a monomer containing acrylic acid in the presence of 1.4 to 4.4 parts by mass of hypophosphorous acid and 0.3 to 1.5 parts by mass of persulfate relative to 100 parts by mass of the above monomer by using an isopropyl alcohol aqueous solution as a solvent At a temperature of 68 to 82 占 폚 and a neutralizing step of neutralizing 15 to 95 mol% of the carboxyl groups of the monomer-derived constituent units constituting the obtained polymer, and having a weight average molecular weight of 4,500 to 8,500 And an acrylic polymer.

Description

DISPERSANT FOR CALCIUM CARBONATE AND METHOD FOR PRODUCING SAME [0002]

The present invention relates to a dispersant for calcium carbonate and a method for producing the same. More particularly, the present invention relates to a dispersant for calcium carbonate, which has low initial viscosity of a calcium carbonate slurry obtained by wet pulverization and suppresses a remarkable increase in viscosity with time, and a method for producing the same.

The calcium carbonate slurry obtained by wet pulverizing calcium carbonate is widely used for a paper coating agent, a paint pigment, and the like. In the production of the calcium carbonate slurry, a dispersant for calcium carbonate is used in order to lower the viscosity of the resulting calcium carbonate slurry.

As the dispersant for calcium carbonate, a dispersant containing an acrylic polymer is used to obtain a slurry having a low viscosity.

As a method for obtaining this dispersant, for example, Patent Document 1 discloses a method for producing a polymer having a small molecular weight by using water as a solvent and using a large amount of a molecular weight regulator such as sodium hypophosphite. However, when the dispersant obtained by this method was used, the viscosity of the obtained calcium carbonate slurry was high, and the viscosity was remarkably increased with time.

On the other hand, as a method which does not use a molecular weight modifier such as sodium hypophosphite, for example, Patent Document 2 discloses a vinyl monocarboxylic acid (salt) having a weight average molecular weight of 4,000 to 40,000 and an Mw / Mn of 1.2 to 2.0, As a polymerization initiator, a persulfate as a polymerization initiator, and isopropyl alcohol as a reaction solvent and a molecular weight regulator. Also in Patent Documents 3 and 4, a method of producing a dispersant by using persulfate as a polymerization initiator and isopropyl alcohol as a reaction solvent and molecular weight regulator is disclosed as in Patent Document 2.

Japanese Patent Laid-Open Publication No. 60-174793 Japanese Patent Application Laid-Open No. 2004-306022 Japanese Patent Application Laid-Open No. 2004-315359 WO2004 / 087574

However, in the production methods described in the above Patent Documents 2 to 4, since the persulfate salt alone is used as the polymerization initiator, the performance of the obtained dispersant is not yet sufficiently satisfactory.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a dispersant for calcium carbonate having a low initial viscosity of the obtained calcium carbonate slurry, a remarkable increase in viscosity with time, The purpose.

The inventors of the present invention have conducted intensive studies in view of the above problems and found that a calcium carbonate slurry obtained by wet pulverization or the like is low in initial viscosity and little in viscosity increase over time and thus used as an aqueous solution of isopropyl alcohol A polymerization step of polymerizing a monomer containing acrylic acid in the presence of a hypophosphite and a persulfate and a neutralization step of neutralizing 15 to 95 mol% of a carboxyl group of the monomer-derived constituent unit constituting the obtained polymer , A dispersant for calcium carbonate is obtained in which the initial viscosity of the obtained calcium carbonate slurry is low and a remarkable increase in viscosity with time is suppressed.

The present invention is as follows.

1. A process for polymerizing a monomer containing acrylic acid in the presence of a hypophosphorous salt and a persulfate using an aqueous solution of isopropyl alcohol as a solvent and a process for polymerizing a monomer containing acrylic acid in an amount of 15 to 95 mol % By weight based on the total weight of the acrylic polymer,

The amount of the hypophosphite used is 1.4 to 4.4 parts by mass based on 100 parts by mass of the monomer,

The amount of the persulfate used is 0.3 to 1.5 parts by mass based on 100 parts by mass of the monomer,

The reaction temperature of the polymerization step is 68 to 82 占 폚,

Wherein the acrylic polymer has a weight average molecular weight of 4,500 to 8,500.

2. The dispersant for calcium carbonate as described in 1 above, which comprises a concentration step of distilling off isopropyl alcohol after the polymerization step.

3. The dispersant for calcium carbonate according to item 2, wherein isopropyl alcohol recovered by the distillation removal in the concentration step is used in the polymerization step.

4. The dispersant for calcium carbonate according to any one of 1 to 3 above, wherein the aqueous isopropyl alcohol solution has an isopropyl alcohol concentration of 15 to 55 mass%.

5. The dispersant for calcium carbonate according to any one of 1 to 4, wherein the acrylic acid used in the polymerization step is contained in an amount of 80 to 100 mass% based on 100 mass% of the total amount of the monomer.

6. A process for producing a dispersant for calcium carbonate, which comprises an acrylic polymer,

A polymerization step of polymerizing a monomer containing acrylic acid in the presence of a hypophosphite and a persulfate using an isopropyl alcohol aqueous solution as a solvent,

And a neutralization step of neutralizing 15 to 95 mol% of the carboxyl groups of the monomer-derived constituent units constituting the obtained polymer,

The amount of the hypophosphite used is 1.4 to 4.4 parts by mass based on 100 parts by mass of the monomer,

The amount of the persulfate used is 0.3 to 1.5 parts by mass based on 100 parts by mass of the monomer,

The reaction temperature of the polymerization step is 68 to 82 占 폚,

Wherein the acrylic polymer has a weight average molecular weight of 4,500 to 8,500.

7. The method for producing a dispersant for calcium carbonate as described in 6 above, which further comprises a step of concentrating the isopropyl alcohol by distillation after the polymerization step.

8. The method for producing a dispersant for calcium carbonate as described in 7 above, wherein isopropyl alcohol recovered by the distillation removal in the concentration step is used in the polymerization step.

9. The method for producing a dispersant for calcium carbonate according to any one of 6 to 8 above, wherein the aqueous isopropyl alcohol solution has an isopropyl alcohol concentration of 15 to 55 mass%.

10. The method for producing a dispersant for calcium carbonate according to any one of 6 to 9 above, wherein the acrylic acid used in the polymerization step is contained in an amount of 80 to 100 mass% based on 100 mass% of the whole monomer.

INDUSTRIAL APPLICABILITY The calcium carbonate dispersant of the present invention exhibits excellent dispersibility of calcium carbonate, and particularly exhibits excellent dispersibility and long-term dispersion stability as a dispersant for wet pulverization of calcium carbonate. INDUSTRIAL APPLICABILITY The dispersant for calcium carbonate of the present invention can be obtained by using isopropyl alcohol having the action of a molecular weight regulator as a solvent and by using a hypophosphite as a molecular weight regulator and a persulfate as a polymerization initiator in combination with phosphites and phosphates It is possible to obtain a dispersant for calcium carbonate having few by-products such as sulfate which is a by-product of persulfate. By using the dispersant for calcium carbonate of the present invention, it is possible to obtain a calcium carbonate slurry in which the initial viscosity of the resulting calcium carbonate slurry is low and a remarkable increase in viscosity with time is suppressed.

When the acrylic acid used in the polymerization step is contained in an amount of 80 to 100% by mass based on 100% by mass of the total amount of the monomer, it is possible to obtain a dispersing agent for calcium carbonate having better dispersibility of calcium carbonate.

INDUSTRIAL APPLICABILITY The method for producing a calcium carbonate dispersant of the present invention can efficiently produce a calcium carbonate dispersant that forms a calcium carbonate slurry in which the initial viscosity of a calcium carbonate slurry is low and a remarkable increase in viscosity with time is suppressed.

In addition, when a step of concentrating isopropyl alcohol is carried out after the above-mentioned polymerization step, a dispersant for calcium carbonate having reduced isopropyl alcohol can be efficiently produced.

When the isopropyl alcohol recovered by the distillation removal in the concentration step is used in the polymerization step, the isopropyl alcohol which has been distilled off is reused in the polymerization step and does not need to be discarded, so that the cost can be reduced, And a method of producing a dispersant for calcium carbonate having excellent environmental preservation.

When the acrylic acid used in the polymerization step is contained in an amount of 80 to 100% by mass based on 100% by mass of the total amount of the monomers, a dispersant for calcium carbonate having better dispersibility of calcium carbonate can be efficiently produced.

Hereinafter, the dispersant for calcium carbonate of the present invention (hereinafter simply referred to as " dispersant ") and the method for producing the dispersant for calcium carbonate of the present invention will be described in detail.

The present invention relates to a process for polymerizing a monomer containing acrylic acid in the presence of a hypophosphite and a persulfate by using an isopropyl alcohol aqueous solution as a solvent and a process for polymerizing a monomer containing acrylic acid in the presence of a monomer Wherein the amount of the hypophosphite used is in the range of 1.4 to 4.4 parts by mass based on 100 parts by mass of the monomer, And the amount of the persulfate used is 0.3 to 1.5 parts by mass with respect to 100 parts by mass of the monomer, the reaction temperature of the polymerization step is 68 to 82 占 폚, and the weight average molecular weight of the acrylic polymer is 4,500 to 8,500 do.

In the present specification, the term " (meth) acryl " is used to mean one or both of acrylic and methacrylic.

The dispersant of the present invention is obtained by including the polymerization step and the neutralization step. The raw materials used for forming the dispersant of the present invention will be described.

In the polymerization step, the monomer to be polymerized by the polymerization reaction is a monomer containing at least acrylic acid. Therefore, the whole amount of the monomer may be acrylic acid, or a part of the monomer may contain acrylic acid.

Monomers other than acrylic acid (hereinafter also referred to as " other monomers ") are not particularly limited as long as they are monomers copolymerizable with acrylic acid. Specifically, a vinyl monomer having a radical polymerizing property (a polymerizable unsaturated compound) can be mentioned. Examples of the vinyl monomer include an ethylenically unsaturated carboxylic acid other than acrylic acid, a neutralized salt of an ethylenically unsaturated carboxylic acid, a (meth) acrylic acid alkyl ester compound, an aromatic vinyl compound, an acid anhydride, an amino group- Containing vinyl compound, a sulfonic acid group-containing vinyl compound, a polyoxyalkylene group-containing vinyl compound, an alkoxyl group-containing vinyl compound, a cyano group-containing vinyl compound, a cyanide vinyl compound, a vinyl ether compound, a vinyl ester compound and a conjugated diene. These may be used alone or in combination of two or more.

Of these, a (meth) acrylic acid alkyl ester compound and a polyoxyalkylene group-containing vinyl compound are preferable from the viewpoint of physical properties (dispersion stability, coloring inhibition, etc.) of the obtained dispersant.

Examples of the ethylenically unsaturated carboxylic acid other than acrylic acid include half esterified methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, phthalic anhydride with alkyl alcohol, And half-esterified with an alkyl alcohol.

Examples of the neutralized salt of the ethylenically unsaturated carboxylic acid include an ethylenically unsaturated carboxylic acid salt in which a carboxyl group is neutralized such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid and crotonic acid. Examples of the ethylenically unsaturated carboxylic acid salt include an alkali metal salt, an alkaline earth metal salt, an ammonium salt and an organic amine salt.

Examples of the (meth) acrylic acid alkyl ester compound include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (Meth) acrylate, n-hexyl (meth) acrylate, 2-methylpentyl (meth) acrylate, n-butyl (meth) acrylate, sec- (Meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl , Cyclohexyl (meth) acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate.

Examples of the aromatic vinyl compound include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene,? -Methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, tert-butoxystyrene, vinyltoluene, vinylnaphthalene, halogenated styrene, styrenesulfonic acid, and? -methylstyrenesulfonic acid.

Examples of the acid anhydride monomers include maleic anhydride, itaconic anhydride, and citraconic anhydride.

Examples of the amino group-containing vinyl compound include dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) (Meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, 2-diethylaminopropyl (meth) acrylate, 2- 3-dimethylaminopropyl acrylate, 3-diethylaminopropyl (meth) acrylate, and 3- (di-n-propylamino) propyl (meth) acrylate.

Examples of the amide group-containing vinyl compound include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide and N-methylol have.

Examples of the sulfonic acid group-containing vinyl compound include methallylsulfonic acid and acrylamide-2-methyl-2-propanesulfonic acid.

Examples of the polyoxyalkylene group-containing vinyl compound include (meth) acrylic acid esters of alcohols having polyoxyethylene group and / or polyoxypropylene group.

Examples of the alkoxyl group-containing vinyl compound include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (n-propoxy) Propyl (meth) acrylate, 2- (n-butoxy) ethyl (meth) acrylate, 3- methoxypropyl ) Propyl and the like.

Examples of the (meth) acrylic acid ester compound having a cyano group include cyanomethyl (meth) acrylate, 1-cyanoethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, (Meth) acrylate, 2-cyanopropyl (meth) acrylate, 3-cyanopropyl (meth) acrylate, 4-cyanobutyl Cyanohexyl, 8-cyanooctyl (meth) acrylate, and the like.

Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, and ethacrylonitrile.

Examples of the vinyl ether compound include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether and vinyl cyclohexyl ether. These may be used alone or in combination of two or more.

Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, and vinyl propionate.

Examples of the conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, , 5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like.

In addition, maleimide-based compounds such as maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide and N-cyclohexylmaleimide; Maleic ester compounds; Itaconic acid ester compounds; And N-vinyl heterocyclic compounds such as vinyl pyridine.

Of these other monomers, preferred are methyl acrylate, butyl acrylate, and the like. Use of methyl acrylate, butyl acrylate or the like in combination with acrylic acid can provide a dispersant excellent in inhibition of coloring.

In the case where the monomer includes other monomers other than acrylic acid in the polymerization step, the content of acrylic acid is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 80% by mass or more, based on 100% Is not less than 90% by mass. Particularly preferably 100% by mass, and the total amount of the monomers is acrylic acid. When the content of acrylic acid is 70 mass% or more, the solubility of the resulting dispersant in water can be made sufficient.

In the polymerization step, hypophosphite is used as a chain transfer agent. The hypophosphite is not particularly limited as long as it is a compound having a chain transfer function, and specific examples thereof include sodium hypophosphite, potassium hypophosphite, lithium hypophosphite, calcium hypophosphite, magnesium hypophosphite and barium hypophosphite. These may be used alone or in combination of two or more. Of these, sodium hypophosphite is preferred.

The amount of the hypophosphite used is 1.4 to 4.4 parts by mass, preferably 2.0 to 4.0 parts by mass, and more preferably 2.5 to 3.5 parts by mass based on 100 parts by mass of the monomer. When the amount of the hypophosphite is within the above range, a polymer having a weight average molecular weight of 4,500 to 8,500 is efficiently obtained. When the amount of the hypophosphite used is 4.4 parts by mass or less, a dispersant having a low content of by-produced phosphites and phosphates is obtained. As a result, the initial viscosity of the calcium carbonate slurry obtained by wet pulverization is low and the viscosity A remarkable increase is suppressed, and a dispersant having excellent long-term dispersion stability can be obtained. Further, when the amount of the hypophosphite to be used is large (for example, when the amount is more than 4.4 parts by mass), the initial viscosity of the calcium carbonate slurry becomes high and a remarkable increase in viscosity occurs over time. It is presumed that the by-products phosphite and phosphate increase from the hypophosphite, and the viscosity of the by-product increases due to the formation of the poorly soluble compound in the calcium carbonate.

In the polymerization step, persulfate is used as a polymerization initiator (radical polymerization initiator). The persulfate salt is not particularly limited, but specific examples thereof include sodium persulfate, ammonium persulfate, and potassium persulfate. These may be used alone or in combination of two or more. Of these, sodium persulfate and potassium persulfate are preferable in that volatile components are hardly generated in the neutralization step performed after the polymerization step.

The amount of the persulfate used is 0.3 to 1.5 parts by mass, preferably 0.4 to 1.4 parts by mass, more preferably 0.6 to 1.2 parts by mass based on 100 parts by mass of the monomer. If the amount of the persulfate used is within the above range, unreacted monomers can be reduced. When the amount of the persulfate used is 1.5 parts by mass or less, a dispersant having a small content of by-produced sulphate may be used. Further, when the amount of the persulfate used is large (for example, when the amount of the persulfate used is larger than 1.5 parts by mass), the initial viscosity of the calcium carbonate slurry becomes high and a remarkable increase in viscosity occurs over time. As in the case of hypophosphite, it is presumed that the by-product sulphate generated from the persulfate increases and the viscosity of the by-product increases due to the formation of the poorly soluble compound in the calcium carbonate.

In the polymerization step, an aqueous solution of isopropyl alcohol is used as a solvent.

In addition, isopropyl alcohol also acts as a chain transfer agent in the polymerization process. Therefore, an aqueous isopropyl alcohol solution is used as a reaction solvent and a chain transfer agent.

The isopropyl alcohol concentration of the isopropyl alcohol aqueous solution is preferably 5% by mass or more and 90% by mass or less, more preferably 10% by mass to 80% by mass, still more preferably 15% by mass to 60% by mass, 55% by mass, and may be 20 to 50% by mass or 30 to 50% by mass.

If the concentration of isopropyl alcohol is 5% by mass or more, the effect of chain transfer as a chain transfer agent of isopropyl alcohol effectively works. Further, when the concentration of isopropyl alcohol is increased, the action of the chain transfer effect is also excellent.

The amount of isopropyl alcohol used in the polymerization step is preferably 15 to 80 parts by mass, and more preferably 45 to 75 parts by mass based on 100 parts by mass of the monomer. When the amount of isopropyl alcohol used is 15 parts by mass or more, the chain transfer effect of isopropyl alcohol effectively works. When the amount is 80 parts by mass or less, solubility of the raw material is improved.

Wherein the polymerization step comprises polymerizing a monomer containing acrylic acid with a monomer containing acrylic acid in the presence of a hypophosphite and a persulfate by using an aqueous solution of isopropyl alcohol as a reaction solvent to obtain a first monomer having a structural unit derived from the monomer To obtain a polymer.

The reaction temperature in the above polymerization step is 68 to 82 占 폚, preferably 70 to 80 占 폚. By controlling the reaction temperature to be 82 占 폚 or less, it is possible to smoothly proceed the polymerization and to prevent the hypophosphoric acid, which is a molecular weight regulator, from being oxidized to a phosphite or a phosphate, thereby obtaining a dispersant having a low content of phosphite and phosphate as by- . When the reaction temperature is 68 占 폚 or higher, a dispersant having a small amount of unreacted monomers can be obtained.

The above-mentioned polymerization step may be a batch polymerization method or a continuous polymerization method. In the batch polymerization method, the time required for the step of supplying the raw material (raw material composition) containing the monomers is preferably 2 to 12 hours, more preferably 3 to 8 hours. When the required time is 2 hours or more, heat removal of the polymerization heat is facilitated, and when the time is 12 hours or less, the productivity is improved.

The reaction apparatus can use a known reactor in batch polymerization, and it is preferable to have a stirrer and a device for temperature control. The stirrer is not particularly limited as long as a known stirrer is installed, and examples of the stirrer include anchor wing, puddle wing, propeller wing, turbine wing, ribbon wing or large flat wing. As the temperature regulating device, a known internal and / or external heat exchanger such as a jacket, an inner coil or a plate type heat exchanger may be adopted. Further, a baffle or the like may be arranged in the reactor as needed for the purpose of improving stirring efficiency and the like.

In the case of the continuous polymerization method, the step is preferably carried out by a multi-stage CSTR (continuous stirred tank reactor having a plurality of reaction tanks). In this case, the average residence time of each reaction tank is preferably 60 to 240 minutes, more preferably 80 to 180 minutes. When the average residence time is 60 minutes or more, unreacted monomers can be reduced. If the time is 240 minutes or less, the size of the reaction tank can be reduced.

Even in the case of continuous polymerization, the same apparatus as the above-mentioned batch system can be used for the stirrer and the temperature controlling apparatus.

The polymerization method for obtaining the first polymer in the polymerization step is not particularly limited. For example, the following embodiments (1) to (3) can be mentioned.

(1) A predetermined amount of isopropyl alcohol aqueous solution is placed in a reaction vessel. Then, a raw material mixture containing a monomer, an aqueous solution of isopropyl alcohol and a hypophosphite, and a persulfate are dropped into a reaction vessel to carry out a polymerization reaction.

(2) A raw material mixture containing a monomer, an isopropyl alcohol aqueous solution and a hypophosphite is prepared, and the raw material mixture and persulfate are added dropwise to a reaction vessel to carry out a polymerization reaction.

(3) An isopropyl alcohol aqueous solution is added to the reaction vessel, and maintained at the same temperature or near the reaction temperature. The monomers, hypophosphite and persulfate are then added dropwise to the reaction vessel to carry out the polymerization reaction.

From the standpoint of obtaining a homogeneous polymer among them, the embodiment of (1) is preferable.

As a specific example of the above (1), a predetermined amount (20 to 80% by mass of the total amount) of isopropyl alcohol aqueous solution is held in advance in the reaction vessel at the same temperature as or close to the reaction temperature. On the other hand, a raw material mixture containing an aqueous solution of isopropyl alcohol, a monomer and a hypophosphite added to the reaction vessel is prepared. Then, the raw material mixture and the persulfate may be dropped into the reaction vessel containing an isopropyl alcohol aqueous solution to carry out the polymerization reaction.

The initial viscosity of the calcium carbonate slurry obtained when the dispersant is used by using isopropyl alcohol having the action of a molecular weight regulator in the polymerization process as a solvent and by using a hypophosphite as a molecular weight regulator and a persulfate as a polymerization initiator And the calcium carbonate slurry having a low viscosity and a marked increase in viscosity over time can be suppressed. This is because the addition amount of the hypophosphite and persulfate to be used is reduced and there are few by-products such as phosphates and sulphates which are by-produced from hypophosphites and siphosphates derived from hypophosphites, The initial viscosity of the slurry is low, and a remarkable increase in viscosity with time is suppressed.

By the polymerization process, a first polymer formed from a monomer containing acrylic acid is obtained. The weight average molecular weight of the first polymer is preferably 4500 to 8500. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using a standard material such as sodium polyacrylate. When the weight average molecular weight of the first polymer is 4500 to 8500, the weight average molecular weight of the acrylic polymer obtained after the neutralization step may be 4500 to 8500.

The neutralization step is a step of neutralizing a carboxyl group contained in the monomer-derived constituent unit constituting the first polymer obtained by the polymerization step. By this neutralization step, a part of the carboxyl groups is neutralized, and an acrylic polymer contained in the dispersing agent can be obtained.

The neutralization of the carboxyl group in the neutralization step can be carried out by a basic compound. The basic compound is not particularly limited as long as it is a compound capable of neutralizing a carboxyl group, and examples thereof include an inorganic basic compound and an organic basic compound. These may be used alone or in combination of two or more.

Examples of the inorganic basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, and ammonia water.

Examples of the organic basic compound include organic amine compounds such as monoethanolamine and triethanolamine. Among these basic compounds, an alkali metal hydroxide which generates less volatile components is preferable, and sodium hydroxide is more preferable.

The amount (neutralization ratio) of neutralizing the carboxyl groups of the first polymer in the neutralization step is 15 to 95 mol%, preferably 20 to 90 mol%. When the neutralization ratio is 15 to 95 mol%, a dispersing agent having excellent dispersing performance for dispersing calcium carbonate can be obtained.

The acrylic polymer is a polymer in which a monomer containing acrylic acid is polymerized and a part of the carboxyl group derived from the monomer is neutralized. In some cases, the terminal of the acrylic polymer includes a structure derived from hypophosphite and persulfate used for the polymerization.

The weight average molecular weight of the acrylic polymer is 4500 to 8500, preferably 5000 to 8000. The weight average molecular weight can be measured by GPC using a standard material such as sodium polyacrylate as described above. When the weight average molecular weight of the acrylic polymer is within the above range, a dispersing agent having excellent dispersing ability for dispersing calcium carbonate can be obtained, and a dispersant having low initial viscosity of the obtained calcium carbonate slurry and little increase in viscosity over time can be obtained .

In addition to the polymerization step and the neutralization step, the dispersing agent of the present invention may further include a concentration step after the polymerization step. It is preferable that the concentration step be provided between the polymerization step and the neutralization step.

In the concentration step, isopropyl alcohol is distilled off from the reaction solution containing the first polymer obtained by the polymerization step to obtain a concentrated composition in which isopropyl alcohol is reduced.

In the concentration step, isopropyl alcohol can be flowed out of the system by reducing the pressure of the reaction system and / or by heating the reaction system. Thereby, isopropyl alcohol can be distilled off from the reaction solution. The isopropyl alcohol to be distilled off is usually an azeotropic mixture with water. Therefore, in the concentration step, isopropyl alcohol is distilled off from the reaction solution as an aqueous solution, resulting in a concentrated composition in which isopropyl alcohol and water are reduced.

The method of distilling off isopropyl alcohol in the concentration step is not particularly limited. For example, water and isopropyl alcohol can be flowed out of the system by reducing the pressure of the reaction system and maintaining the inner temperature at or above the azeotropic temperature of isopropyl alcohol. Further, water and isopropyl alcohol may be flowed out of the system by allowing the reaction solution to pass through the reduced-thickness thin film evaporator.

The content of isopropyl alcohol contained in the concentrated composition obtained by the concentration process is preferably 1% by mass or less, more preferably 5000 ppm by mass or less, further preferably 2000 ppm by mass or less, particularly preferably 1000 mass% ppm or less.

The isopropyl alcohol aqueous solution which is distilled off in the concentration step can be recovered. The recovered isopropyl alcohol aqueous solution can be used repeatedly in the polymerization step. In the case of reusing an isopropyl alcohol aqueous solution, there is no need to dispose of distilled isopropyl alcohol, thereby reducing the cost, a dispersing agent for calcium carbonate excellent in production efficiency and excellent in environmental preservation, and a method for producing a dispersant for calcium carbonate .

Further, when the aqueous isopropyl alcohol solution is recovered, the concentration of the isopropyl alcohol aqueous solution may be changed before and after the recovery. This is because isopropyl alcohol to be recovered is recovered after being distilled off as an azeotropic mixture of isopropyl alcohol and water. Therefore, even if a high concentration isopropyl alcohol aqueous solution is used in the polymerization step, the isopropyl alcohol concentration of the recovered isopropyl alcohol aqueous solution is It is usually about 60% by mass or less.

On the other hand, in the above-mentioned polymerization step, even if the recovered isopropyl alcohol aqueous solution is reused for the purpose of streamlining the production process, it is preferable to use the isopropyl alcohol aqueous solution at a constant concentration. That is, when the concentration of isopropyl alcohol is set to a high concentration of not less than 60% by mass, the concentration of the recovered isopropyl alcohol aqueous solution may be lowered by distillation than before the recovery. In this case, it is necessary to concentrate the recovered isopropyl alcohol aqueous solution to a high concentration. Depending on the concentration of the isopropyl alcohol aqueous solution, the concentration of the recovered isopropyl alcohol aqueous solution may be higher than before the recovery. When the concentration of recovered isopropyl alcohol aqueous solution becomes higher than that before recovery, the concentration may be adjusted by adding new water. However, when the recovered isopropyl alcohol aqueous solution is concentrated to have a high concentration, a concentration facility is required and the production efficiency is low.

Therefore, the isopropyl alcohol concentration of the isopropyl alcohol aqueous solution is lower than the isopropyl alcohol concentration of the isopropyl alcohol aqueous solution recovered in the concentration step, so that the isopropyl alcohol aqueous solution can be reused. The concentration of isopropyl alcohol for recovering and using the isopropyl alcohol aqueous solution is preferably 15 to 55 mass%, more preferably 20 to 50 mass%, and still more preferably 30 to 50 mass%. When the recovered isopropyl alcohol aqueous solution is reused, the isopropyl alcohol aqueous solution is preferably reused in the polymerization process by adjusting the isopropyl alcohol concentration.

The concentrated composition obtained by the concentration step is subjected to the neutralization step to neutralize a part of the carboxyl groups of the first polymer to obtain an acrylic polymer contained in the dispersing agent.

The dispersant of the present invention includes the acrylic polymer obtained by the above polymerization process and the neutralization process and may be a solution in which the acrylic polymer is dissolved in an aqueous medium or a dispersion in which an acrylic polymer is dispersed in an aqueous medium . Further, the aqueous medium is a medium containing water, which may be water or a mixture containing water.

As the dispersant of the present invention, it is also possible to use a reaction liquid (a) comprising the reaction product obtained by the polymerization step and the neutralization step, or a reaction solution (b) obtained by the polymerization step, the concentration step and the neutralization step The dispersant of the present invention can be used. From the viewpoint of obtaining a dispersant efficiently from these, it is preferable to use the reaction liquid (b) as a dispersant. These dispersants may also be obtained by further adding an aqueous medium.

The reaction solution (b) may be prepared by mixing the hypophosphite and / or its by-product, the persulfate and / or its by-product used in the polymerization process, the basic Or a compound thereof. Also, isopropyl alcohol may contain isopropyl alcohol in an amount corresponding to the content after the concentration step in the reaction solution (b).

The content of isopropyl alcohol in the reaction liquid (b) may be 1% by mass or less, preferably 5000 ppm by mass or less, more preferably 2000 ppm by mass or less, further preferably 1000 ppm by mass or less Or less.

When the dispersant of the present invention is the reaction solution (b), the pH and solid content concentration are not particularly limited. The pH is preferably 3 to 8, more preferably 3 to 7. The solid concentration is preferably 35 to 55%, and more preferably 40 to 50%.

In addition, the dispersant of the present invention may further contain other components such as defoamer and preservative.

Examples of the antifoaming agent include polyether-based, mineral oil-based, silicone-based, and amide-based antifoaming agents. When the dispersant of the present invention contains the defoaming agent, the content thereof is preferably 0.01 to 1.0% by mass based on 100 parts by mass of the acrylic polymer.

Examples of the preservative include isothiazoline type and paraben. When the dispersant of the present invention contains the above-mentioned preservative, its content is preferably 0.001 to 1.0% by mass based on 100 parts by mass of the acrylic polymer.

The dispersant of the present invention may be a solution or dispersion in which the acrylic polymer and the above other components to be incorporated as required are contained in an aqueous medium.

When the dispersant of the present invention contains the above other components, the other components are added and mixed. The mixing is not particularly limited and can be carried out by a known method.

When the calcium carbonate slurry is obtained by using the dispersant of the present invention, the blending amount of the dispersing agent is not particularly limited, but it is preferably from 0.1 to 10.0 parts by mass of the acrylic polymer and from 25 to 100 parts by mass of the aqueous medium to 100 parts by mass of the calcium carbonate .

Then, a calcium carbonate slurry can be obtained by wet pulverizing a mixture of the calcium carbonate and the acrylic polymer blended as described above by a known method.

The dispersant of the present invention is excellent in dispersibility of calcium carbonate and is preferably used as a dispersant for calcium carbonate in the case of obtaining calcium carbonate slurry by wet pulverizing calcium carbonate. The calcium carbonate slurry obtained using the dispersant of the present invention has a low initial viscosity, a marked increase in viscosity over time, and a long-term dispersion stability.

When the dispersant of the present invention contains the above other components, the acrylic polymer may be mixed with other components added as needed. When the dispersant of the present invention is an aqueous solution or dispersion of an aqueous medium containing an acrylic polymer, other components are added to the aqueous solution and dispersion as necessary and mixed. The mixing is not particularly limited and can be carried out by a known method.

<Examples>

EXAMPLES Hereinafter, examples of the present invention will be described with reference to synthesis examples and comparative examples, but the scope of the present invention is not limited to these examples. In the following, &quot; part &quot; and &quot;% &quot; are based on mass unless otherwise specified.

"Mw" in Synthesis Examples, Examples and Comparative Examples means weight average molecular weight. This &quot; Mw &quot; was measured by gel permeation chromatography (GPC). The measurement conditions of this GPC were as follows: HLC8020 system (manufactured by Tosoh Corporation) was used as a GPC apparatus, and G4000PWxl, G3000PWxl and G2500PWxl columns (both columns, manufactured by Tosoh Corporation) were used. In addition, the eluent was 0.1M NaCl + phosphate buffer (pH 7), and the calibration curve was prepared using polyacrylic acid Na (manufactured by Sowa Kagaku Co., Ltd.).

The viscosity of the slurry of heavy calcium carbonate after wet pulverization in the Synthesis Examples, Examples and Comparative Examples and the viscosity of the slurry after standing at 25 占 폚 for 7 days were measured using a B-type viscometer at 25 占 폚 and 60 rpm Respectively.

The median diameter of the slurry of the heavy calcium carbonate after the wet grinding and the 1.32 mu m undergarment value of the slurry after the wet grinding of the slurry were measured with a laser diffraction scattering particle size distribution analyzer LA-910 (manufactured by Horiba Seisakusho Co., Ltd.) ).

&Lt; Preparation of dispersant for calcium carbonate and production of heavy calcium carbonate slurry >

Example 1-1 (Production of Dispersant 1-1 and Production of Slurry Using Dispersant 1-1)

500 g of an aqueous solution containing 36% isopropyl alcohol (hereinafter simply referred to as &quot; IPA &quot;) concentration was placed in a flask equipped with a stirrer and a condenser, and maintained at 80 deg. Subsequently, a mixed solution obtained by mixing 600 g of acrylic acid (hereinafter simply referred to as "AA"), 20 g of sodium hypophosphite and 270 g of an aqueous solution having an IPA concentration of 36% and 40 g of a 15% aqueous solution of sodium persulfate was dropwise added to the flask over 4 hours (Polymerization). After completion of dropwise addition, the reaction solution was reacted (polymerized) by maintaining at 80 캜 for 1 hour. Subsequently, IPA was distilled off under reduced pressure while adding deionized water to the resulting reaction solution until the IPA concentration became 1000 ppm by mass or less. Subsequently, the reaction solution in which IPA was distilled off under reduced pressure was maintained at 80 占 폚, and a 32% sodium hydroxide aqueous solution was supplied so as to have a neutralization ratio of 22 mol%. Thus, a dispersant 1-1 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 1-1 was obtained. The Mw of the acrylic polymer 1-1 contained in the dispersant 1-1 was 6,000. Table 1 shows the amount of each raw material used in the production of the dispersant, the concentration of each raw material, and the ratio of the raw material to 100 parts of the monomer.

17 g of the dispersant 1-1 obtained above, 320 g of ion-exchanged water, and 900 g of heavy calcium carbonate ("TANKAL A", manufactured by Maruo Calcium Co., Ltd.) were charged into a cylindrical vessel, and the mixture was uniformly mixed with gentle stirring. Subsequently, 3000 g of media (1 mm? Ceramic beads) was placed in the cylindrical container and stirred at 1000 rpm for 50 minutes to wet-crush the heavy calcium carbonate. Thereafter, the slurry was recovered through a 200-mesh filter cloth and ion-exchanged water was added to adjust the solid content to 75% to obtain a slurry of heavy calcium carbonate. The viscosity immediately after the wet pulverization of the slurry and the viscosity after standing at 25 占 폚 for 7 days were measured as described above. As a result, the viscosity immediately after the wet pulverization was 210 mPa 占 퐏 and the viscosity after 7 days was 1800 mPa 占 퐏 Respectively.

Further, the median diameter of the slurry immediately after the wet pulverization and the 1.32 μm undercoat value of the slurry were measured as described above. As a result, the median diameter was 0.67 μm and the under value of 1.32 μm was 100%. These results are shown in Table 1.

In the following Examples and Comparative Examples, the amounts of each of the raw materials used in the production of the dispersant, the concentration of each raw material, and the ratio of the raw materials to 100 parts of the monomers are shown in Tables 1 to 6. In the following examples and comparative examples, Mw of the acrylic polymer contained in the dispersing agent, viscosity of the slurry of the heavy calcium carbonate after the wet pulverization, viscosity of the slurry after standing at 25 DEG C for 7 days The viscosity, the median diameter of the slurry of heavy calcium carbonate after the wet pulverization, and the 1.32 μm undercoat value of the slurry after the wet pulverization of the slurry were measured, and the measurement results are shown in Tables 1 to 6.

Example 1-2 (Preparation of dispersant 1-2 and preparation of slurry using dispersant 1-2)

In Example 1-2, Dispersant 1-2 was prepared by using the IPA aqueous solution which had been distilled off and recovered in the production of Dispersant 1-1 in Example 1-1.

The concentration of the IPA aqueous solution recovered in Example 1-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 1-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 1 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 1-2 -2.

Using the obtained dispersant 1-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 2-1 (Production of Dispersant 2-1 and Production of Slurry Using Dispersant 2-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 48%, to obtain an acrylic polymer 2- 1 was obtained with a solid content concentration of 40% and a pH of 4.

Using the obtained dispersant 2-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 2-2 (Production of Dispersant 2-2 and Production of Slurry Using Dispersant 2-2)

In Example 2-2, dispersant 2-2 was prepared by using IPA aqueous solution which had been distilled off and recovered in the production of dispersant 2-1 in Example 2-1. The concentration of the IPA aqueous solution recovered in Example 2-1 was measured, and the concentration of IPA was 48%. Since the concentration of this IPA aqueous solution was the same as that of IPA used in Example 2-1, the concentration was not adjusted. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 2-1 except that the recovered IPA aqueous solution was used to obtain a dispersion agent 2-A having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 2-2. 2.

Using the obtained dispersant 2-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 2-1.

Example 3-1 (Production of Dispersant 3-1 and Production of Slurry Using Dispersant 3-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 17 g to obtain a solid content concentration of acrylic polymer 3-1 And 40% and a pH of 4 were obtained.

Using the obtained dispersant 3-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 3-2 (Production of Dispersant 3-2 and Production of Slurry Using Dispersant 3-2)

In Example 3-2, Dispersant 3-2 was prepared by using the IPA aqueous solution which had been distilled off and recovered in the production of Dispersant 3-1 in Example 3-1.

The concentration of the IPA aqueous solution recovered in Example 3-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 3-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 3-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 3 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 3-2 -2.

Using the obtained dispersant 3-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 3-1.

Example 4-1 (Production of Dispersant 4-1 and Production of Slurry Using Dispersant 4-1)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the amount of the aqueous sodium persulfate solution in Example 1-1 was changed from 40 g to 30 g to obtain a solid content concentration of the acrylic polymer 4-1 Of 40% and a pH of 4 was obtained.

Using the obtained dispersant 4-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 4-2 (Production of Dispersant 4-2 and Production of Slurry Using Dispersant 4-2)

In Example 4-2, dispersant 4-2 was prepared by using IPA which was distilled and recovered in the production of dispersant 4-1 in Example 4-1.

The concentration of the IPA aqueous solution recovered in Example 4-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 4-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 4-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 4 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 4-2 -2.

Using the obtained dispersant 4-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 4-1.

Example 5-1 (Production of Dispersant 5-1 and Production of Slurry Using Dispersant 5-1)

Except that the holding temperature in the flask of IPA in Example 1-1, the reaction temperature in the polymerization, and the temperature in the neutralization were changed from 80 캜 to 75 캜, polymerization, distillation under reduced pressure And neutralization were carried out to obtain a dispersant 5-1 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 5-1.

Using the obtained dispersant 5-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 5-2 (Production of Dispersant 5-2 and Production of Slurry Using Dispersant 5-2)

In Example 5-2, dispersant 5-2 was prepared by using IPA obtained by removing distillate in the preparation of dispersant 5-1 in Example 5-1 and recovering.

The concentration of the IPA aqueous solution recovered in Example 5-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water in order to make it equal to the concentration of the IPA aqueous solution used in Example 5-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 5-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 5 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 5-2 -2.

Using the obtained dispersant 5-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 5-1.

Example 6-1 (Production of Dispersant 6-1 and Production of Slurry Using Dispersant 6-1)

The polymerization, the distillation under reduced pressure and the neutralization were carried out in the same manner as in Example 1-1 except that the neutralization ratio by the aqueous solution of 32% sodium hydroxide in Example 1-1 was changed from 22 mol% to the neutralization ratio of 40 mol% A dispersant 6-1 having a solid content concentration of 40% and a pH of 5 including the acrylic polymer 6-1 was obtained.

Using the obtained dispersant 6-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 6-2 (Production of Dispersant 6-2 and Production of Slurry Using Dispersant 6-2)

In Example 6-2, dispersant 6-2 was prepared by using IPA obtained by removing distillation and recovering in the production of dispersant 6-1 in Example 6-1.

The concentration of the IPA aqueous solution recovered in Example 6-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water in order to make it equal to the concentration of the IPA aqueous solution used in Example 6-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 6-1 except that the IPA aqueous solution with the adjusted concentration was used to obtain a dispersant 6 having a solid concentration of 40% and a pH of 5 including the acrylic polymer 6-2 -2.

Using the obtained dispersant 6-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 6-1.

Example 7-1 (Production of Dispersant 7-1 and Production of Slurry Using Dispersant 7-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 20% 1 was obtained with a solid content concentration of 40% and a pH of 4.

Using the obtained dispersant 7-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 7-2 (Production of Dispersant 7-2 and Production of Slurry Using Dispersant 7-2)

In Example 7-2, dispersant 7-2 was produced by using IPA obtained by removing distillation and recovering in the production of dispersant 7-1 in Example 7-1.

The concentration of the IPA aqueous solution recovered in Example 7-1 was measured, and the concentration of IPA was 25%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 20% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 7-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 7-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 7 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 7-2 -2.

Using the obtained dispersant 7-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 7-1.

Example 8-1 (Production of Dispersant 8-1 and Production of Slurry Using Dispersant 8-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 53%, to obtain an acrylic polymer 8- 1 was obtained. The dispersant 8-1 having a solid concentration of 40% and a pH of 4 was obtained.

Using the obtained dispersant 8-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 8-2 (Production of Dispersant 8-2 and Production of Slurry Using Dispersant 8-2)

In Example 8-2, dispersant 8-2 was prepared by using IPA which was distilled and recovered in the production of dispersant 8-1 in Example 8-1.

The concentration of the IPA aqueous solution recovered in Example 8-1 was measured and the concentration of IPA was 53%. Since the concentration of the IPA aqueous solution was the same as that of the IPA aqueous solution used in Example 8-1, the concentration was not adjusted. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 8-1 to obtain a dispersant 8-2 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 8-2.

Using the obtained dispersant 8-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 8-1.

Example 9-1 (Production of Dispersant 9-1 and Production of Slurry Using Dispersant 9-1)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 9.5 g to obtain a solid content A dispersant 9-1 having a concentration of 40% and a pH of 4 was obtained.

Using the obtained dispersant 9-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 9-2 (Production of Dispersant 9-2 and Production of Slurry Using Dispersant 9-2)

In Example 9-2, Dispersant 9-2 was prepared by using the IPA aqueous solution which had been distilled off and recovered in the production of Dispersant 9-1 in Example 9-1.

The concentration of the IPA aqueous solution recovered in Example 9-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 9-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 9-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 9 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 9-2 -2.

Using the obtained dispersant 9-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 9-1.

Example 10-1 (Production of Dispersant 10-1 and Production of Slurry Using Dispersant 10-1)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 26.5 g to obtain a solid content A dispersant 10-1 having a concentration of 40% and a pH of 4 was obtained.

Using the obtained dispersant 10-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 10-2 (Production of Dispersant 10-2 and Production of Slurry Using Dispersant 10-2)

In Example 10-2, a dispersant 10-2 was prepared by using the IPA aqueous solution which had been distilled off at the time of producing the dispersant 10-1 in the above-mentioned Example 10-1.

The concentration of the IPA aqueous solution recovered in Example 10-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so that the concentration of the recovered IPA aqueous solution became the same as that of the IPA aqueous solution used in Example 10-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 10-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 10 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 9-2 -2.

Using the obtained dispersant 10-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 10-1.

Example 11-1 (Production of Dispersant 11-1 and Production of Slurry Using Dispersant 11-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the amount of aqueous sodium persulfate solution in Example 1-1 was changed from 40 g to 12 g to obtain a solid concentration of acrylic polymer 11-1 Of 40% and a pH of 4 was obtained.

Using the obtained dispersant 11-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 11-2 (Preparation of dispersant 11-2 and production of slurry using dispersant 11-2)

In Example 11-2, dispersant 11-2 was prepared by using IPA which was distilled and recovered in the production of dispersant 11-1 in Example 11-1.

The concentration of the IPA aqueous solution recovered in Example 11-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 11-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 11-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 11 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 11-2 -2.

Using the obtained dispersant 11-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 11-1.

Example 12-1 (Production of Dispersant 12-1 and Production of Slurry Using Dispersant 12-1)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the amount of the aqueous sodium persulfate solution in Example 1-1 was changed from 40 g to 60 g to obtain a solid content concentration of the acrylic polymer 12-1 Of 40% and a pH of 4 was obtained.

Using the obtained dispersant 12-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 12-2 (Production of Dispersant 12-2 and Production of Slurry Using Dispersant 12-2)

In Example 12-2, dispersant 12-2 was prepared by using IPA which was distilled and recovered in the production of dispersant 12-1 in Example 12-1.

The concentration of the IPA aqueous solution recovered in Example 12-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water in order to make it equal to the concentration of the IPA aqueous solution used in Example 12-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 12-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 12 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 12-2 -2.

Using the obtained dispersant 12-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 12-1.

Example 13-1 (Production of Dispersant 13-1 and Production of Slurry Using Dispersant 13-1)

The polymerization, decompression distillation and neutralization were carried out in the same manner as in Example 1-1 except that the neutralization ratio by the aqueous solution of 32% sodium hydroxide in Example 1-1 was changed from 22 mol% to the neutralization ratio of 18 mol% A dispersant 13-1 having a solid content concentration of 40% and a pH of 3 including the acrylic polymer 13-1 was obtained.

Using the obtained dispersant 13-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 13-2 (Production of Dispersant 13-2 and Production of Slurry Using Dispersant 13-2)

In Example 13-2, dispersant 13-2 was prepared by using IPA which was distilled off and recovered in the production of dispersant 13-1 in Example 13-1.

The concentration of the IPA aqueous solution recovered in Example 13-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 13-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 13-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 13 having a solid content concentration of 40% and a pH of 3 including the acrylic polymer 13-2 -2.

Using the obtained dispersant 13-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 13-1.

Example 14-1 (Production of Dispersant 14-1 and Production of Slurry Using Dispersant 14-1)

The polymerization, decompression distillation, and neutralization were carried out in the same manner as in Example 1-1 except that the neutralization ratio by the aqueous solution of 32% sodium hydroxide in Example 1-1 was changed from 22 mol% to the neutralization ratio of 90 mol% A dispersant 14-1 having a solid content concentration of 40% and a pH of 7 including the acrylic polymer 14-1 was obtained.

Using the obtained dispersant 14-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 14-2 (Preparation of dispersant 14-2 and production of slurry using dispersant 14-2)

In Example 14-2, Dispersant 14-2 was prepared by using IPA obtained by removing distillate in the preparation of Dispersant 14-1 in Example 14-1.

The concentration of the IPA aqueous solution recovered in Example 14-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Example 14-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 14-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 14 having a solid concentration of 40% and a pH of 7 including the acrylic polymer 14-2 -2.

Using the obtained dispersant 14-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 14-1.

Example 15-1 (Production of Dispersant 15-1 and Production of Slurry Using Dispersant 15-1)

The procedure of Example 1-1 was repeated, except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 65% and the amount of sodium hypophosphite was changed from 20 g to 15 g, And subjected to vacuum distillation removal and neutralization to obtain a dispersant 15-1 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 15-1.

Using the obtained dispersant 15-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 15-2 (Production of Dispersant 15-2 and Production of Slurry Using Dispersant 15-2)

In Example 15-2, dispersant 15-2 was prepared by using the IPA aqueous solution which was removed by distillation in the production of dispersant 15-1 in Example 15-1. The concentration of the IPA aqueous solution recovered in Example 15-1 was measured, and the concentration of IPA was 55%. In order to make the recovered IPA aqueous solution equal to the concentration of the IPA aqueous solution used in Example 15-1, IPA was concentrated and adjusted to an aqueous solution having an IPA concentration of 65%. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 15-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 15 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 15-2 -2.

Using the obtained dispersant 15-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 15-1.

Example 16-1 (Production of dispersant 16-1 and production of slurry using dispersant 16-1)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the monomer containing 600 g of acrylic acid in Example 1-1 was changed to 575 g of acrylic acid and 25 g of methyl acrylate and that methyl acrylate was used in addition to acrylic acid , A dispersant 16-1 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 16-1 was obtained.

Using the obtained dispersant 16-1, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Example 16-2 (Production of Dispersant 16-2 and Production of Slurry Using Dispersant 16-2)

In Example 16-2, dispersant 16-2 was prepared by using IPA obtained by removing distillate in the production of dispersant 16-1 in Example 16-1.

The concentration of the IPA aqueous solution recovered in Example 16-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water to make it equal to the concentration of the IPA aqueous solution used in Example 16-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 16-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 16 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 16-2 -2.

Using the obtained dispersant 16-2, a heavy calcium carbonate slurry was obtained in the same manner as in Example 16-1.

Comparative Example 1-1 (Production of Dispersant 1-1C and Production of Slurry Using Dispersant 1-1C)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 10% and the acrylic polymer 1- Dispersant 1-1C having a solid concentration of 40% and a pH of 4 including 1C was obtained.

Using the obtained dispersant 1-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 1-2 (Preparation of Dispersant 1-2C and Production of Slurry Using Dispersant 1-2C)

In Comparative Example 1-2, dispersant 1-2C was prepared by using IPA obtained by removing distillate in the preparation of Dispersant 1-1C in Comparative Example 1-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 1-1 was measured, and the concentration of IPA was 20%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 10% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 1-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 1-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 1 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 1-2C -2C.

Using the obtained dispersant 1-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 1-1.

Comparative Example 2-1 (Production of Dispersant 2-1C and Production of Slurry Using Dispersant 2-1C)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 65%, to obtain an acrylic polymer 2- Dispersant 2-1C having a solids concentration of 40% and a pH of 4 including 1C was obtained.

Using the obtained dispersant 2-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 2-2 (Production of Dispersant 2-2C and Production of Slurry Using Dispersant 2-2C)

In Comparative Example 2-2, dispersant 2-2C was prepared by using IPA obtained by removing distillate in the production of dispersant 2-1C in Comparative Example 2-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 2-1 was measured, and the concentration of IPA was 55%. In order to make the recovered IPA aqueous solution equal to the concentration of the IPA aqueous solution used in Comparative Example 2-1, IPA was concentrated and adjusted to an aqueous solution having an IPA concentration of 65%. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 2-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 2 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 2-2C -2C.

Using the obtained dispersant 2-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 2-1.

Comparative Example 3-1 (Production of Dispersant 3-1C and Production of Slurry Using Dispersant 3-1C)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 6 g to obtain a solid concentration of acrylic polymer 3-1C And a pH of 4 was obtained.

Using the obtained dispersant 3-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 3-2 (Production of Dispersant 3-2C and Production of Slurry Using Dispersant 3-2C)

In Comparative Example 3-2, Dispersant 3-2C was prepared by using IPA obtained by removing distillate in the production of Dispersant 3-1C in Comparative Example 3-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 3-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 3-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 3-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 3 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 3-2C -2C.

Using the obtained dispersant 3-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 3-1.

Comparative Example 4-1 (Production of Dispersant 4-1C and Production of Slurry Using Dispersant 4-1C)

Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Example 1-1 except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 33 g to obtain a solid content concentration of acrylic polymer 4-1C 4% &lt; / RTI &gt;

Using the obtained dispersant 4-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 4-2 (Production of Dispersant 4-2C and Production of Slurry Using Dispersant 4-2C)

In Comparative Example 4-2, dispersant 4-2C was prepared by using IPA obtained by removing distillate in the production of dispersant 4-1C in Comparative Example 4-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 4-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so that the concentration of the recovered IPA aqueous solution became the same as that of the IPA aqueous solution used in Comparative Example 4-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 4-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 4 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 4-2C -2C.

Using the obtained dispersant 4-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 4-1.

Comparative Example 5-1 (Production of Dispersant 5-1C and Production of Slurry Using Dispersant 5-1C)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the amount of aqueous sodium persulfate solution in Example 1-1 was changed from 40 g to 7 g to obtain a solid concentration of acrylic polymer 5-1C And a pH of 4 was obtained.

Using the obtained dispersant 5-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 5-2 (Production of Dispersant 5-2C and Production of Slurry Using Dispersant 5-2C)

In Comparative Example 5-2, Dispersant 5-2C was prepared by using IPA obtained by removing distillate in the production of Dispersant 5-1C in Comparative Example 5-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 5-1 was measured. As a result, the IPA concentration was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 5-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 5-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 5 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 5-2C -2C.

Using the obtained dispersant 5-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 5-1.

Comparative Example 6-1 (Production of Dispersant 6-1C and Production of Slurry Using Dispersant 6-1C)

Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 except that the amount of aqueous sodium persulfate solution in Example 1-1 was changed from 40 g to 80 g to obtain a solid concentration of acrylic polymer 6-1C And dispersant 6-1C having a pH of 4 was obtained.

Using the obtained dispersant 6-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 6-2 (Production of Dispersant 6-2C and Production of Slurry Using Dispersant 6-2C)

In Comparative Example 6-2, dispersant 6-2C was prepared by using IPA obtained by removing distillate in the production of dispersant 6-1C in Comparative Example 6-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 6-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 6-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 6-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 6 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 6-2C -2C.

Using the obtained dispersant 6-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 6-1.

Comparative Example 7-1 (Production of Dispersant 7-1C and Production of Slurry Using Dispersant 7-1C)

The polymerization, decompression and distillation in the same manner as in Example 1-1, except that the holding temperature in the IPA flask, the reaction temperature in the polymerization, and the temperature in neutralization were changed from 80 ° C to 60 ° C in Example 1-1, Neutralization was carried out to obtain a dispersant 7-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 7-1C.

Using the obtained dispersant 7-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 7-2 (Production of Dispersant 7-2C and Production of Slurry Using Dispersant 7-2C)

In Comparative Example 7-2, dispersant 7-2C was prepared by using IPA which was distilled and recovered in the production of dispersant 7-1C in Comparative Example 7-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 7-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water in order to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 7-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 7-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 7 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 7-2C -2C.

Using the obtained dispersant 7-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 7-1.

Comparative Example 8-1 (Production of Dispersant 8-1C and Production of Slurry Using Dispersant 8-1C)

In the same manner as in Example 1-1 except that the holding temperature in the IPA flask, the reaction temperature in the polymerization, and the neutralization temperature were changed from 80 캜 to 89 캜 in Example 1-1, polymerization, Neutralization was carried out to obtain a dispersant 8-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 8-1C.

Using the obtained dispersant 8-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 8-2 (Preparation of Dispersant 8-2C and Production of Slurry Using Dispersant 8-2C)

In Comparative Example 8-2, dispersant 8-2C was prepared by using IPA obtained by removing distillate at the time of preparation of dispersant 8-1C in Comparative Example 8-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 8-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 8-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 8-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 8 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 8-2C -2C.

Using the obtained dispersant 8-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 8-1.

Comparative Example 9-1 (Production of Dispersant 9-1C and Production of Slurry Using Dispersant 9-1C)

The polymerization, decompression distillation and neutralization were carried out in the same manner as in Example 1-1 except that the neutralization ratio by the 32% sodium hydroxide aqueous solution in Example 1-1 was changed from 22 mol% to the neutralization ratio of 10 mol% A dispersant 9-1C having a solid content concentration of 40% and a pH of 2 including the acrylic polymer 9-1C was obtained.

Using the obtained dispersant 9-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 9-2 (Production of Dispersant 9-2C and Production of Slurry Using Dispersant 9-2C)

In Comparative Example 9-2, dispersant 9-2C was prepared by using IPA which was distilled off and recovered in the production of dispersant 9-1C in Comparative Example 9-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 9-1 was measured. As a result, the IPA concentration was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 9-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 9-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 9 having a solid content concentration of 40% and a pH of 2 including acrylic polymer 8-2C -2C.

Using the obtained dispersant 9-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 9-1.

Comparative Example 10-1 (Production of Dispersant 10-1C and Production of Slurry Using Dispersant 10-1C)

The polymerization, decompression distillation and neutralization were carried out in the same manner as in Example 1-1 except that the neutralization ratio by the aqueous solution of 32% sodium hydroxide in Example 1-1 was changed from 22 mol% to the neutralization ratio of 98 mol% A dispersant 10-1C having a solid content concentration of 40% and a pH of 9 including the acrylic polymer 10-1C was obtained.

Using the obtained dispersant 10-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 10-2 (Production of Dispersant 10-2C and Production of Slurry Using Dispersant 10-2C)

In Comparative Example 10-2, Dispersant 10-2C was prepared by using IPA obtained by removing distillation and recovering in the production of Dispersant 10-1C in Comparative Example 10-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 10-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 10-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 10-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 10 having a solid content concentration of 40% and a pH of 9 including the acrylic polymer 10-2C -2C.

Using the obtained dispersant 10-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 10-1.

Comparative Example 11-1 (Production of Dispersant 11-1C and Production of Slurry Using Dispersant 11-1C)

The procedure of Example 1-1 was repeated, except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 10% and the aqueous sodium persulfate solution was changed from 40 g to 80 g, Vacuum distillation removal and neutralization were carried out to obtain a dispersant 11-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 11-1C.

Using the obtained dispersant 11-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 11-1.

Comparative Example 11-2 (Production of Dispersant 11-2C and Production of Slurry Using Dispersant 11-2C)

In Comparative Example 11-2, dispersant 11-2C was prepared by using IPA obtained by removing the distillate at the time of production of dispersant 11-1C in Comparative Example 11-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 11-1 was measured, and the IPA concentration was found to be 20%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 10% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 11-1. Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Comparative Example 11-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 11 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 11-2C -2C.

Using the obtained dispersant 11-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 11-1.

Comparative Example 12-1 (Production of Dispersant 12-1C and Production of Slurry Using Dispersant 12-1C)

The procedure of Example 1-1 was repeated, except that the amount of sodium hypophosphite in Example 1-1 was changed from 20 g to 6 g, and the amount of the aqueous sodium persulfate solution was changed from 40 g to 80 g, To obtain a dispersant 12-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 12-1C.

Using the obtained dispersant 12-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 1-1.

Comparative Example 12-2 (Production of Dispersant 12-2C and Production of Slurry Using Dispersant 12-2C)

In Comparative Example 12-2, dispersant 12-2C was prepared by using IPA obtained by removing distillate in the production of dispersant 12-1C in Comparative Example 12-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 12-1 was measured, and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water in order to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 12-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 12-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 12 having a solid concentration of 40% and a pH of 4 including the acrylic polymer 12-2C -2C.

Using the obtained dispersant 12-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 12-1.

Comparative Example 13-1 (Production of Dispersant 13-1C and Production of Slurry Using Dispersant 13-1C)

The procedure of Example 1-1 was repeated, except that the aqueous solution having an IPA concentration of 36% in Example 1-1 was changed to an aqueous solution having an IPA concentration of 10% and the amount of sodium hypophosphite was changed from 20 g to 33 g, Distillation removal and neutralization were carried out to obtain a dispersant 13-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 13-1C.

Using the obtained dispersant 13-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 13-1.

Comparative Example 13-2 (Production of Dispersant 13-2C and Production of Slurry Using Dispersant 13-2C)

In Comparative Example 13-2, Dispersant 13-2C was prepared by using IPA obtained by removing the distillate in the production of Dispersant 13-1C in Comparative Example 13-1.

The concentration of the IPA aqueous solution recovered in Comparative Example 13-1 was measured, and the concentration of IPA was found to be 20%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 10% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 13-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 13-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersion agent 13 having a solid content concentration of 40% and a pH of 4 including the acrylic polymer 13-2C -2C.

Using the obtained dispersant 13-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 13-1.

Comparative Example 14-1 (Production of Dispersant 14-1C and Production of Slurry Using Dispersant 14-1C)

Except that the holding temperature in the IPA flask, the reaction temperature in the polymerization, and the temperature in neutralization were changed from 80 ° C to 60 ° C and the amount of the aqueous sodium persulfate solution was changed from 40g to 80g in Example 1-1 Polymerization, vacuum distillation removal and neutralization were carried out in the same manner as in Example 1-1 to obtain a dispersant 14-1C having a solid concentration of 40% and a pH of 4 including the acrylic polymer 14-1C.

Using the obtained dispersant 14-1C, a heavy calcium carbonate slurry was obtained in the same manner as in Example 14-1.

Comparative Example 14-2 (Production of Dispersant 14-2C and Production of Slurry Using Dispersant 14-2C)

In Comparative Example 14-2, dispersant 14-2C was prepared by using IPA which was distilled at the time of preparation of dispersant 14-1C in Comparative Example 14-1 and recovered.

The concentration of the IPA aqueous solution recovered in Comparative Example 11-1 was measured and the concentration of IPA was 40%. The recovered IPA aqueous solution was adjusted to an aqueous solution having an IPA concentration of 36% by adding deionized water so as to make it equal to the concentration of the IPA aqueous solution used in Comparative Example 14-1. Polymerization, vacuum distillation and neutralization were carried out in the same manner as in Comparative Example 14-1 except that the IPA aqueous solution having the adjusted concentration was used to obtain a dispersant 14 having a solid content concentration of 40% and a pH of 4 including acrylic polymer 14-2C -2C.

Using the obtained dispersant 14-2C, a heavy calcium carbonate slurry was obtained in the same manner as in Comparative Example 14-1.

In Examples 1-1 to 16-2, the amounts of sodium hypophosphite and sodium persulfate used were in the range of 1.4 to 4.4 parts and 0.3 to 1.5 parts, respectively, with respect to 100 parts by mass of the monomer, and the reaction temperature of the polymerization step was 68 to 82 占 폚 , The weight average molecular weight of the resulting acrylic polymer is 4,500 to 8,500, and the neutralization ratio of the carboxyl group is 15 to 95 mol%. From the above results, it was found that the dispersants of Examples 1-1 to 16-2 were low in the initial viscosity of the calcium carbonate slurry obtained by the wet pulverization, and were suppressed from remarkably increasing in viscosity with time.

On the other hand, in Comparative Examples 1-1 and 1-2, since the weight average molecular weight of the acrylic polymer was as large as 11000, the slurry viscosity at the time of crushing of calcium carbonate was high and the slurry viscosity after 7 days was also remarkably increased. In Comparative Examples 2-1 and 2-2, the slurry viscosity at the time of pulverization of calcium carbonate was small, but the weight average molecular weight of the acrylic polymer was too small at 4300 and 4200, so that the slurry viscosity after 7 days was remarkably increased. In addition, in Comparative Examples 1-1 and 1-2, the weight average molecular weight of the acrylic polymer was large, and in Comparative Examples 2-1 and 2-2, the weight average molecular weight of the acrylic polymer was small. The molecular weight of the acrylic polymer (first polymer) can be adjusted by the amount of IPA when the amount of hypophosphite and persulfate used is specified. That is, the amounts of IPA used in Comparative Examples 1-1 and 1-2 were 13 parts relative to 100 parts of the monomer, which was smaller than that of Example 1-1, and the amounts of IPA used in Comparative Examples 2-1 and 2-2 were 83 parts The molecular weight of the acrylic polymer is affected thereby. In addition, since the concentration of the IPA aqueous solution used in Comparative Examples 2-1 and 2-2 was as high as 65%, when the recovered IPA was reused, the recovered IPA aqueous solution (azeotropic mixture) needed to be concentrated.

In Comparative Examples 3-1 and 3-2, since the amount of sodium hypophosphite used was small as one part with respect to 100 parts of the monomer, the weight average molecular weight of the acrylic polymer was increased to 10900 and 10800, and the slurry viscosity at the time of crushing calcium carbonate was And a remarkable increase was also observed in the slurry viscosity after 7 days.

Further, in Comparative Examples 4-1 and 4-2, since the amount of sodium hypophosphite used was as large as 5.5 parts per 100 parts of the monomer, the weight average molecular weight of the acrylic polymer was small, but the slurry viscosity at the time of pulverization of calcium carbonate was high, Lt; RTI ID = 0.0 &gt;%, &lt; / RTI &gt;

In Comparative Examples 5-1 and 5-2, since the amount of sodium persulfate used is as small as 0.2 part per 100 parts of the monomer, the weight average molecular weight of the acrylic polymer is as large as 9,100 and 9900, unreacted acrylic acid becomes large, The slurry viscosity at the time of pulverization was high and the slurry viscosity after 7 days was also remarkably increased. Incidentally, in Comparative Example 5-1, acrylic acid was mixed in the recovered IPA aqueous solution, and the reuse of the recovered IPA was considered unsuitable.

In Comparative Examples 6-1 and 6-2, since the amount of sodium persulfate used was as large as 2.0 parts per 100 parts of the monomer, the weight average molecular weight of the acrylic polymer was within an appropriate range. However, the slurry viscosity at the time of pulverization of calcium carbonate was high A remarkable increase was also observed in the slurry viscosity after 7 days.

Further, in Comparative Examples 7-1 and 7-2, since the reaction temperature in the polymerization step was as low as 60 占 폚, the weight average molecular weight of the acrylic polymer was slightly increased, the unreacted acrylic acid was increased, And the slurry viscosity after 7 days was also remarkably increased. Incidentally, in Comparative Example 7-1, acrylic acid was mixed in the recovered IPA aqueous solution, and the reuse of the recovered IPA was deemed unsuitable.

In addition, in Comparative Examples 8-1 and 8-2, since the reaction temperature in the polymerization step was as high as 89 캜, the weight average molecular weight of the acrylic polymer was within an appropriate range. However, the slurry viscosity at the time of pulverization of calcium carbonate was high A remarkable increase was also observed in the slurry viscosity after 7 days.

Further, in Comparative Examples 9-1 and 9-2, since the neutralization ratio of the carboxyl group was as low as 10 mol%, the calcium carbonate could not be pulverized and no slurry was obtained. In addition, in Comparative Examples 10-1 and 10-2, since the neutralization ratio of the carboxyl group was as high as 98 mol%, it was possible to crush calcium carbonate, but the slurry viscosity at the time of crushing of calcium carbonate was high and the slurry viscosity after 7 days A remarkable rise was also observed.

Further, in Comparative Examples 11-1 and 11-2, the amount of sodium persulfate used was increased to 2 parts per 100 parts of the monomer, while the amount of IPA used was changed to 13 parts per 100 parts of the monomer to make the weight average molecular weight of the acryl- Respectively. As a result, the weight average molecular weight of the obtained acrylic polymer was within a suitable range of around 7,400, but since the amount of sodium persulfate used was large, the slurry viscosity at the time of crushing of calcium carbonate was high and the slurry viscosity after 7 days was also remarkably increased.

In Comparative Examples 12-1 and 12-2, the amount of sodium persulfate used was increased to 2 parts per 100 parts of monomers, while the amount of sodium hypophosphite used was changed to 100 parts of monomers to make the weight average molecular weight of the acrylic polymer within the appropriate range . As a result, the weight average molecular weight of the obtained acrylic polymer was within a suitable range of about 6900, but since the amount of sodium persulfate used was also large, the slurry viscosity at the time of pulverization of calcium carbonate was high and the slurry viscosity after 7 days was also remarkably increased .

In addition, in Comparative Examples 13-1 and 13-2, the amount of sodium hypophosphite used was increased to 5.5 parts per 100 parts of the monomer, while the amount of IPA used was changed to 100 parts of the monomer to make the weight average molecular weight of the acryl- 13 copies. As a result, the weight average molecular weight of the obtained acrylic polymer was within a suitable range of about 7,100, but since the amount of sodium hypophosphite used was large, the slurry viscosity at the time of crushing of calcium carbonate was high and also the slurry viscosity after 7 days was remarkably increased .

In Comparative Examples 14-1 and 14-2, the amount of sodium persulfate used was increased to 2 parts per 100 parts of the monomer, while the reaction temperature in the polymerization step was 60 占 폚. As a result, the weight average molecular weight of the obtained acrylic polymer was within a suitable range of about 7300, but since the amount of sodium persulfate used was also large, the slurry viscosity at the time of pulverization of calcium carbonate was high and the slurry viscosity after 7 days was also remarkably increased .

INDUSTRIAL APPLICABILITY As described above, the dispersant for calcium carbonate of the present invention exerts excellent calcium carbonate dispersibility and long-term dispersion stability, and thus can be effectively used as a dispersant for wet pulverization of calcium carbonate.

Further, according to the method for producing a dispersant for calcium carbonate of the present invention, the dispersant for calcium carbonate can be efficiently produced. In addition, when isopropyl alcohol recovered in the concentration step of the present invention is used in the polymerization step, there is no need to dispose of distilled isopropyl alcohol, and thus the cost can be reduced, the production efficiency is excellent, A method of producing a dispersant for calcium carbonate can be provided.

Claims (10)

A step of polymerizing a monomer containing acrylic acid in the presence of a hypophosphorous salt and a persulfate by using an aqueous solution of isopropyl alcohol as a solvent and a step of polymerizing a monomer containing acrylic acid in an amount of 15 to 95 mol% And a neutralization step of neutralizing the acrylic polymer,
The amount of the hypophosphite used is 1.4 to 4.4 parts by mass based on 100 parts by mass of the monomer,
The amount of the persulfate used is 0.3 to 1.5 parts by mass based on 100 parts by mass of the monomer,
The reaction temperature of the polymerization step is 68 to 82 占 폚,
Wherein the acrylic polymer has a weight average molecular weight of 4,500 to 8,500. The dispersant for calcium carbonate according to claim 1, which comprises a condensing step of distilling off isopropyl alcohol after the polymerization step. The dispersant for calcium carbonate according to claim 2, wherein the isopropyl alcohol recovered by the distillation removal in the concentration step is used in the polymerization step. 4. The dispersant for calcium carbonate according to any one of claims 1 to 3, wherein the isopropyl alcohol aqueous solution has an isopropyl alcohol concentration of 15 to 55% by mass. The dispersant for calcium carbonate according to any one of claims 1 to 3, wherein the acrylic acid used in the polymerization step is contained in an amount of 80 to 100% by mass based on 100% by mass of the total amount of the monomer. A method for producing a dispersant for calcium carbonate, which comprises an acrylic polymer,
A polymerization step of polymerizing a monomer containing acrylic acid in the presence of a hypophosphite and a persulfate using an isopropyl alcohol aqueous solution as a solvent,
And a neutralization step of neutralizing 15 to 95 mol% of the carboxyl groups of the monomer-derived constituent units constituting the obtained polymer,
The amount of the hypophosphite used is 1.4 to 4.4 parts by mass based on 100 parts by mass of the monomer,
The amount of the persulfate used is 0.3 to 1.5 parts by mass based on 100 parts by mass of the monomer,
The reaction temperature of the polymerization step is 68 to 82 占 폚,
Wherein the acrylic polymer has a weight average molecular weight of 4,500 to 8,500. 7. The method for producing a dispersant for calcium carbonate according to claim 6, comprising a concentration step of distilling off isopropyl alcohol after the polymerization step. The method of producing a dispersant for calcium carbonate according to claim 7, wherein isopropyl alcohol recovered by the distillation removal in the concentration step is used in the polymerization step. 9. The method for producing a dispersant for calcium carbonate according to any one of claims 6 to 8, wherein the isopropyl alcohol aqueous solution has an isopropyl alcohol concentration of 15 to 55 mass%. 9. The method for producing a dispersant for calcium carbonate according to any one of claims 6 to 8, wherein the acrylic acid used in the polymerization step contains 80 to 100% by mass based on 100% by mass of the total amount of the monomer.