JP2002179933A - Dispersant for inorganic powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersant excellent in reduction in initial viscosity of an aqueous dispersion of an inorganic powder and stability with the lapse of time, an aqueous dispersion and an absorbent for flue gas desulfurization. SOLUTION: The dispersant for an inorganic powder (B) containing a hydroxide of a group 2-4 element in the periodic table comprise a carboxylic group- containing polymer (A1) or an acid group-containing (co)polymer (A2) other than (A1) in combination with the polymer (A1), the polymer (A1) being a partial neutralizate of a copolymer (A0) comprising 30-80 mole% of an α,β-unsaturated carboxylic acid (a) with 20-70 mole% of another monomer (b) and the degree of neutralization of the acid groups in (A1) and (A2) being 30-96 mole% as a whole. The aqueous dispersion comprises the dispersant and an inorganic powder (B). The absorbent for flue gas desulfurization comprises the aqueous dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for an inorganic powder, and more particularly, to an inorganic powder containing one or more hydroxides selected from the group consisting of hydroxides of Group 2 to 4 elements. And a dispersant for an aqueous dispersion.

[0002]

2. Description of the Related Art Conventionally, hydroxides of Group 2 to 4 elements of the periodic table,
For example, an aqueous dispersion of an inorganic powder containing calcium hydroxide or magnesium hydroxide is used in the form of an aqueous dispersion as an absorbent for sulfurous acid gas or nitric oxide gas in flue gas desulfurization. The aqueous dispersion used is used at a relatively low concentration (usually less than 30% by weight).

[0003]

The above-mentioned aqueous dispersion is preferably as high as possible in terms of transportability and workability. However, when the concentration is high, the viscosity becomes high and the stability becomes poor. There were problems such as doing.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have reached the present invention.
That is, the present invention relates to a dispersant for an inorganic powder (B) containing a hydroxide of an element in Groups 2 to 4 of the periodic table, wherein the dispersant is a carboxyl group-containing polymer (A1) or another acid. A group-containing (co) polymer (A2);
1) is a partially neutralized product of a copolymer (A ₀ ) of 30 to 80 mol% of α, β-unsaturated carboxylic acid (a) and 20 to 70 mol% of another monomer (b), (A1) and (A2) a dispersant having a total neutralization degree of the acid group of 30 to 96 mol%; the dispersant and a hydroxide of an element in Groups 2 to 4 of the periodic table. An aqueous dispersion containing an inorganic powder (B) containing one or more hydroxides selected from the group; and an absorbent for flue gas desulfurization comprising the aqueous dispersion.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of the α, β-unsaturated carboxylic acid (a) which is a constituent monomer of the copolymer (A ₀ ) include the following. (A1) α, β-unsaturated monocarboxylic acid: (meth) acrylic acid, crotonic acid, etc .; (a2) α, β-unsaturated dicarboxylic acid: (anhydrous) maleic acid [(anhydrous) uses carboxylic anhydride And the following are also included: fumaric acid, itaconic acid,
(Anhydride) itaconic acid, citraconic acid, (anhydrous) citraconic acid and the like; (a3) a half ester of the above α, β-unsaturated dicarboxylic acid: alkanol having 1 to 12 carbon atoms or (poly) oxyalkylene (2 carbon atoms) -4, degree of polymerization 1-100) half ester with alkyl (1-18 carbon atoms) ether,
For example, maleic acid half ester (monobutyl maleate, monoethyl carbitol maleate, etc.), fumaric acid half ester (monobutyl fumarate, monoethyl carbitol fumarate, etc.) and the like. Of these, preferred are itaconic acid (anhydride), maleic acid (anhydride), fumaric acid (anhydride), maleic acid half ester and fumaric acid half ester, and particularly preferred is maleic anhydride.

The other monomer (b) constituting the copolymer (A ₀ ) includes monomers copolymerizable with (a), for example, the following ethylenically unsaturated monomers. However, the present invention is not limited to these.

(B1) Aromatic hydrocarbon monomers: styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, etc. (b2) Hydroxyl group-containing aromatic monomers: hydroxystyrene, etc. (b3) Halogen containing Aromatic monomer: halogen-substituted styrene (such as dichlorostyrene), etc. (b4) Sulfonic acid group-containing aromatic monomer: styrene sulfonic acid, α-methylstyrene sulfonic acid, etc., (b5) carbon number 2 to 20 aliphatic hydrocarbon monomers: ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene,
(B6) an alicyclic monomer having 5 to 15 carbon atoms: cyclopentadiene, pinene, limonene, indene, bicyclopentadiene, ethylidene norbornene, etc. (b7) an alkyl group having 1 to 36 carbon atoms Alkyl (meth) acrylate having: methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. (B8) (poly) alkylene glycol (molecular weight: 62 to
2,000): (poly) alkylene glycol (alkylene having 2 to 4 carbon atoms, polymerization degree 1 to 10)
0) or an ester of an alkyl (C1-18) ether thereof with an unsaturated carboxylic acid (as described above), for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol (molecular weight 88 to 1, 000) mono (meth) acrylate, polypropylene glycol (molecular weight 200 to 1,0
00) mono (meth) acrylate, methyl alcohol ethylene oxide adduct (molecular weight 102-500) (meth) acrylate, lauryl alcohol ethylene oxide adduct (molecular weight 256-1500) (meth) acrylate, etc .; and the above (poly) alkylene glycol Or a mono (meth) allyl ether of an alkyl ether thereof, for example, polyethylene glycol (having a molecular weight of 88 to
(B9) Amide group-containing monomer: (meth) acrylamide, N-methylol (meth) acrylamide, etc. (b10) Sulfonic acid group-containing aliphatic monomer: vinyl sulfonic acid , (Meth) allylsulfonic acid, 2-hydroxy-3- (meth) allyloxypropanesulfonic acid, sulfopropyl (meth) acrylate, 2- (meth) acryloylamino-2,2-dimethylethanesulfonic acid, 2-
(Meth) acryloyloxyethanesulfonic acid, 2-
(Meth) acryloyloxy-2-hydroxypropanesulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 3- (meth) acrylamide-2
-Hydroxypropanesulfonic acid, alkyl (C3
-18) (meth) allylsulfosuccinates, etc.
Other compounds represented by the following general formula (1).

[0008]

Embedded image

In the formula, R represents an alkyl group having 1 to 15 carbon atoms which may be substituted by a fluorine atom.

(B11) Sulfate group-containing monomer: a sulfate ester of poly (n = 2 to 30) oxyalkylene mono (meth) acrylate (the oxyalkylene is an oxyalkylene having 2 to 4 carbon atoms, and , Random, block) [for example, poly (n = 5 to 1)
5) Oxypropylene monomethacrylate sulfate)] and other compounds represented by the following general formulas (2) and (3).

[0011]

Embedded image

In the formula, R 'represents an alkyl group having 1 to 15 carbon atoms, A represents an alkylene group having 2 to 4 carbon atoms, and when n is plural, they may be the same or different; Or a block, Ar represents a benzene ring, and n represents an integer of 1 to 50.

Among these, preferably (b1) to (b)
3), (b5), (b7), (b8), (b10) and (b11), particularly preferably (b1) and (b1).
5) and (b7).

As the structural units of the copolymer (A ₀ ), α,
The content of β-unsaturated carboxylic acid is usually 30 to 80 mol%, preferably 40 to 60 mol%, and the content of other monomers is usually 20 to 70 mol%, preferably 40 to 6 mol%.
0 mol%. When the content of the α, β-unsaturated carboxylic acid is less than 30 mol%, the dispersing effect is insufficient, and when it exceeds 80 mol%, the dispersing effect is insufficient.

The copolymer (A ₀ ) can be obtained by subjecting the monomers (a) and (b) to radical polymerization at 20 to 200 ° C. using a radical polymerization catalyst and, if necessary, a chain transfer agent. it can. Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile,
2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4,4-trimethylpentane), dimethyl 2 , 2′-azobis (2-methylpropionate), 2,2′-azobis [2- (hydroxymethyl) propionitrile], 1,1′-azobis (1-acetoxy-1-phenylethane) and the like Azo compounds; organic peroxides such as dibenzoyl peroxide, dicumyl peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, benzoyl peroxide, lauroyl peroxide, persuccinic acid; persulfates, peroxides Inorganic peroxides such as borate and hydrogen peroxide can be used. Further, a redox-based initiator combined with a reducing agent can be used. Examples of the reducing agent used in the redox initiator include ascorbic acid (salt), Rongalit, hypophosphorous acid (salt), sulfurous acid (salt), bisulfite (salt), and ferrous salt. Two or more kinds may be used in combination. The amount of the radical polymerization initiator is usually from 0.01 to 20% by weight, preferably from 0.05 to 5% by weight, based on the monomer.

Examples of the chain transfer agent include lauryl mercaptan, thioglycolic acid, mercaptoethanol,
Triethylene glycol dimercaptan, tris (polyoxypropylene-2-hydroxy-3-thiolpropane) alkyl ether and the like. The amount of the chain transfer agent is usually 0.01 mol% to 10 mol%, preferably 0.05 to 3 mol%, based on the monomer.

The polymerization method may be any of solution polymerization, emulsion polymerization, suspension and bulk polymerization, but solution polymerization, emulsion polymerization and suspension polymerization are preferred, and solution polymerization is particularly preferred. Solvents for solution polymerization include water, alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, etc.), ethers (tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane,
Heptane), aromatic hydrocarbons (toluene, xylene and the like), halogenated solvents (1,2-dichloroethane and the like), and mixtures thereof.

The polymerization temperature is usually from 20 to 200 ° C, preferably from 60 to 150 ° C. For example, a temperature below the boiling point of the polymerization solution under normal pressure, a boiling point of the polymerization solution under normal pressure, a temperature above the boiling point of the polymerization solution under pressure and the like can be mentioned. Preferred is a method in which the polymerization is carried out at a boiling point of the polymerization solution under normal pressure or higher than the boiling point of the polymerization solution under pressure. When a surfactant is used as an emulsifier in the case of emulsion polymerization, there is no particular limitation, and known surfactants can be used.

The copolymer (A ₀ ) is converted to a sodium salt (100
% Neutralized), the weight average molecular weight (hereinafter abbreviated as Mw) measured by GPC is usually 1,000 to 100,
000. Preferably, 5,000 to 40,000
And the molecular weight distribution (hereinafter abbreviated as Mw / Mn) is usually 1.10 to 6.00, preferably 1.1 to 4.0.
0. When Mw is 1,000 to 100,000, the dispersion effect can be sufficiently exhibited.

In the present invention, acid groups in the copolymer (A ₀ ) [acid groups are usually carboxylic acid groups, but (b4), (b1)
When 0) and / or (b11) is used as a copolymer component, the acid group includes not only a carboxylic acid group but also a sulfonic acid group and / or a sulfate group. ] Is from 30 to 96 mol%, preferably from 50 to 94 mol%
It is. When the degree of neutralization is less than 30 mol%, the dispersing effect is insufficient, and when it exceeds 96 mol%, the dispersing effect is insufficient.

As a method for obtaining the partially neutralized product (A) of the copolymer (A ₀ ) of the present invention, the acid groups in the copolymer (A ₀ ) are adjusted so as to have a predetermined degree of neutralization. The polymer (A ₀ ) is converted from an alkali metal hydroxide or (bi) carbonate (sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, etc.), an alkaline earth metal hydroxide or oxide (hydroxide). Magnesium oxide, calcium hydroxide, calcium oxide, etc.), amines, ammonia, or an aqueous solution thereof for neutralization. Alternatively, before the above-mentioned polymerization, a monomer having an acid group is neutralized in advance so as to have a predetermined degree of neutralization, and the neutralized monomer is adjusted. The partially neutralized product (A) can be obtained by polymerization.

The salts formed by the neutralization include one or more salts selected from the group consisting of alkali metal salts, alkaline earth metal salts, organic amine salts and ammonium salts.

Examples of the alkali metal include lithium, sodium and potassium. Examples of the alkaline earth metal include calcium and magnesium, and these may be used in combination.

Examples of the organic amine include primary, secondary, and tertiary aliphatic amines, alicyclic amines, aromatic amines, alkylene oxide adducts of these primary and secondary amines, and (poly) alkylene polyamines. Can be

(A) As the aliphatic amine, a compound having 1 to 1 carbon atoms
20 alkyl groups and amines having these alkyl groups and a hydroxyl group. Examples of the primary amine having an alkyl group include methylamine, ethylamine, and n.
-Butylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and the like, as the secondary amine having an alkyl group, dimethylamine, diethylamine, dibutylamine, dioctylamine, didecylamine, didodecylamine, Ditetradecylamine, dihexadecylamine, dioctadecylamine, dioleylamine, etc.
Examples of the tertiary amine having an alkyl group include trimethylamine, triethylamine, tri-n-propylamine,
Tri-n-butylamine, diethyl-1-propylamine, octyldimethylamine, decyldimethylamine,
Dodecyldimethylamine, tetradecyldimethylamine, hexadecyldimethylamine, octadecyldimethylamine and the like can be mentioned. Examples of the amine having an alkyl group and a hydroxyl group include alkanolamines (monoalkanolamines such as monoethanolamine, monopropanolamine and monobutanolamine, diethanolamine such as diethanolamine, dipropanolamine and dibutanolamine, and triethanolamine; Trialkanolamines such as tripropanolamine and tributanolamine).

(A) Examples of the alicyclic amine include a cycloalkylamine having a cycloalkyl group, and specific examples thereof include cyclopentylamine, cyclohexylamine, dicyclohexylamine, and cyclohexylmethylamine. (C) As the heterocyclic amine, pyrrolidine, purine, N
-Methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-methylhexamethyleneimine, N-ethylhexamethyleneimine,
N-methylmorpholine, N-butylmorpholine, 1,5
-Diazabicyclo [4,3,0] -5-nonene, 1,8
-Diazabicyclo [5,4,0] -7-undecene and the like.

(D) As the aromatic amine, aniline,
Benzylamine, toluidine, benzidine, pyrimidine, N, N dimethylaniline, phenylenediamine (o, m, p), pyridine, 4-methylbenzimidazole, quinoline, 4,4'-dipyridyl and the like.

(E) The alkylene oxide of the alkylene oxide adduct of the primary or secondary amine includes:
Examples include ethylene oxide, propylene oxide and butylene oxide. These additional moles are usually
1 to 5 mol per active hydrogen, preferably 1 to 2 mol
Is a mole. Specific examples thereof include cyclohexylamine adduct of 2 mol of propylene oxide, dioctylamine adduct of 1 mol of propylene oxide, morpholine adduct of ethylene oxide of 1 mol, and aniline adduct of ethylene oxide of 1 mol.

(F) Examples of the (poly) alkylene polyamine include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and alkylated products thereof.

Among the organic amines, preferred are aliphatic or alicyclic amines or their alkylene oxide adducts.

Examples of the ammonium constituting the ammonium salt include ammonia and quaternary ammonium such as tetraalkylammonium. As the alkyl group constituting the tetraalkylammonium,
An aliphatic alkyl group having 1 to 12 carbon atoms (methyl, ethyl,
Propyl, butyl, hexyl, octyl, dodecyl and the like and alicyclic alkyl groups (cyclohexyl and the like), and the four (cyclo) alkyl groups may be the same or different.

Among the salts, preferred are alkali metal salts and alkaline earth metal salts, and more preferred are sodium salts and potassium salts.

The quaternary ammonium salt can be prepared by a conventional method, for example, using a tertiary amine and an alkyl halide (for example,
Methyl chloride, ethyl bromide, etc.)
A quaternary ammonium halide which is then alkali hydroxide (eg, sodium hydroxide, potassium hydroxide)
To obtain a quaternary ammonium salt hydroxide, which is then used to neutralize the copolymer (A ₀ ); a tertiary amine is converted to a dialkyl (C 1-6) carbonate (eg, dimethyl carbonate) , Diethyl carbonate)
To obtain a quaternary ammonium carbonate, which can be obtained by a method of exchanging anions with the copolymer (A ₀ ). Alternatively, (A ₀ ) may be converted into an amine salt with an amine in advance, and an alkylene oxide may be added thereto to form a quaternary ammonium salt having a hydroxyalkyl group.

The dispersant of the present invention can be usually used in the form of an aqueous solution or a solid (such as a powder). In the case of an aqueous solution, the concentration is usually 1 to 90% by weight, preferably 10 to 60% by weight.
% By weight.

The amount of the dispersant of the present invention is usually 0.01 to 8% by weight (solid content), preferably 0.05 to 3% by weight (solid content), based on the weight of the inorganic powder (B). It is.

The inorganic powder (B) in the present invention is an inorganic powder containing one or more hydroxides (B1) selected from the group consisting of hydroxides of Group 2 to 4 elements of the periodic table.
Group 2 elements include Group 2 A elements (alkaline earth metals), such as magnesium, calcium, barium, and Group 2 B elements such as zinc; Group 3 elements include aluminum; and Group 4 elements. Include titanium, lead and the like. Among (B1), preferred are calcium hydroxide (including calcium hydroxide obtained by a hydration reaction of calcium oxide) and magnesium hydroxide (including magnesium hydroxide obtained by a hydration reaction of magnesium oxide) It is.

In the present invention, (B) may contain another inorganic powder (B2) in addition to (B1).
Examples of (B2) include carbonates of Group 2 elements of the periodic table [magnesium carbonate, calcium carbonate, zinc carbonate, strontium carbonate, barium carbonate, etc.] and oxides of Group 2 elements [magnesium oxide, zinc oxide, barium oxide, etc.], Group 3 element oxides [aluminum oxide etc.] Group 4 element oxides [silicon oxide, titanium oxide, lead oxide etc.] and oxides composed of plural types of these elements [aluminum silicate, aluminum calcium aluminum silicate] Etc.], clay, bentonite and the like.
Patent No. 98331 discloses an inorganic powder. (B
Preferred among 2) are carbonates of Group 2 elements and oxides of Group 2 to 4 elements, particularly calcium carbonate.

The proportion of (B1) in (B) is usually from 10 to 100% by weight, preferably from 30 to 100% by weight.

The average particle size of (B) is usually 0.005 to 1
00μ, preferably 0.01 to 50μ.
The average particle diameter here is a median diameter measured by a particle size distribution analyzer ("LA-700" manufactured by Horiba, Ltd.) by a laser diffraction method.

In the aqueous dispersion containing the dispersant of the present invention and (B), water or water and a water-soluble organic solvent can be used as a dispersion medium. Preferred is water. Examples of the water-soluble organic solvent include lower monohydric alcohols [ethanol, n- and isopropyl alcohol, n-,
iso-, sec- and t-butyl alcohol, etc.], glycols having 2 to 9 carbon atoms [such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and dipropylene glycol] and triols having 3 to 9 carbon atoms [glycerin, etc. And the like. When water and a water-soluble organic solvent are used in combination, the weight ratio of water / water-soluble organic solvent is 50 / 50-9.
9.5 / 0.5, particularly preferably 70/30 to 98/2.

The content (concentration) of (B) in the aqueous dispersion of the present invention is usually 5 to 90% by weight, preferably 10 to 80% by weight.
%, More preferably 30 to 78% by weight. The content (solid content) of the dispersant in the aqueous dispersion is usually 0.0005 to 7.2% by weight, preferably 0.005 to 7.2% by weight.
~ 2.4% by weight.

Although the viscosity of the aqueous dispersion of the present invention varies depending on the content of (B), it is usually from 20 to 6.0 at 25 ° C.
For example, when the aqueous dispersion (B) is 50% by weight, it is usually 50 to 2,000 mPa · s.

The dispersant of the present invention may contain an acid group-containing (co) polymer (A2) other than (A1). (A
2) As α, β-unsaturated carboxylic acid, 30 mol%
Α, β-unsaturated carboxylic acid-based (co) polymers and (co) polymers (A2) containing other acid groups, such as poly (meth) acrylic Sodium acid salt (Mw = 1,000-10
000), sodium polystyrene sulfonate (M
w = 1,000-100,000), sodium polyvinyl sulfonate (Mw = 1,000-100,00)
0), sodium (meth) acrylate (10 mol%) /
Sodium styrenesulfonate (90 mol%) copolymer (Mw = 1,000-100,000), sodium (meth) acrylate (90 mol%) / acrylamide (1
0 mol%) copolymer (Mw = 1,000-100,00
0) and the like. Further, other than (A1), a (co) polymer (A3) containing no acid group may be contained. (A
3) As poly (meth) acrylamide (Mw =
1,000-100,000) and polyvinyl alcohol (Mw = 1,000-100,000). The amount of (A2) and / or (A3) is usually 0 to 8% by weight (solid content) based on the weight of the inorganic powder (B). The ratio of (A2) + (A3) is usually 0 to 80% based on the total weight of the dispersant (solid content),
Preferably 0 to 50%, more preferably 0.1 to 20
%. When (A2) is added, the neutralization degree of the acid groups of (A1) and (A2) of the present invention as a whole is 30.
The added amount is within 96 mol%.

If necessary, other additives can be added. Other additives include a thickener, an antifoaming agent, a wetting agent, and the like. As the thickener, polyethylene oxide (Mw: 100,000-
6,000,000), polyacrylamide (Mw: 1)
00,000 to 1,000,000), carboxymethyl cellulose (salt) (Mw: 500,000 to 1,50)
000). The amount of the thickener added is 0 to 10%, preferably 0.0%, based on the total amount of the inorganic powder.
01-5%, more preferably 0.001-1%. In the case of a thickener containing an acid group, the degree of neutralization of the dispersant of the present invention is not included in the calculation. Examples of the antifoaming agent include alcohols having 1 to 36 carbon atoms, fats and oils, mineral oils, polyethers and silicones. The amount of the defoamer added is 0 to 1%, preferably 0.001 to 0.02%, based on the weight of the aqueous dispersion.

The total amount of the above (A2), (A3) and other additives usually does not exceed 8% by weight (solid content) based on the weight of the inorganic powder (B).

As a method for obtaining the dispersion of the present invention, an ordinary method for producing a dispersion may be used. For example, the inorganic powder (B) is added to an aqueous solvent in which the dispersant of the present invention is dissolved, and the mixture is stirred.
A method of mixing is used. The order of addition at this time may be any. For this stirring and mixing, a commonly used stirring device such as a high-speed disper, a homomixer, and a ball mill can be used.

The aqueous dispersion of the present invention comprises an aqueous dispersion such as an absorbent for flue gas desulfurization (sulfurous acid gas, nitric oxide gas absorbent, etc.), an additive for wastewater treatment, a pigment / filler for paints, and papermaking. It can be effectively used as an aqueous dispersion of pigments and fillers. If used for these purposes,
As it is or diluted with water (concentration of inorganic powder 1 ~
80%) can be used.

[0048]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The percentages and parts in Production Examples and Comparative Production Examples represent% by weight and parts by weight.

The conditions for measuring the molecular weight by GPC are as follows. The molecular weight is a value when completely neutralized with sodium hydroxide. << GPC measurement conditions >> Model: Waters510 (manufactured by Nippon Waters Limited) Column: TSK gel G5000pwXL TSK gel G3000pwXL (all manufactured by Tosoh Corporation) Column temperature: 40 ° C. Detector: RI solvent: 0.5% sodium acetate・ Water / methanol (volume ratio 70/30) Flow rate: 1.0 ml / min Sample concentration: 0.25% by weight Injection volume: 200 μl Standard: polyoxyethylene glycol (manufactured by Tosoh Corporation; TSK STANDARD POLYETHYLENE OXIDE) Data processing Apparatus: SC-8010 (manufactured by Tosoh Corporation)

Production Example 1 A glass reactor equipped with a stirrer, a dropping funnel, a nitrogen inlet, a thermometer and a reflux condenser was charged with 250 parts of methyl ethyl ketone, 98 parts of maleic anhydride, and 11 parts of diisobutylene.
2 parts and 0.7 parts of lauryl mercaptan were charged,
The gas phase of the reaction vessel was replaced with nitrogen, and the temperature was raised to 80 ° C.
Under stirring, 36 parts of a 10% solution of azobisisobutyronitrile in methyl ethyl ketone was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was aged at the same temperature for 4 hours to give a conversion of 99.8%
A polymer (a ₀ ) was obtained. The obtained polymer (a ₀ ) was subjected to GP
Mw measured under C measurement conditions was 13,000, Mw / Mn
Was 2.65. After charging 750 parts of water, the mixture was neutralized with 173.3 parts of a 30% aqueous sodium hydroxide solution, a portion of methyl ethyl ketone and water were distilled off, and a maleic acid / diisobutylene copolymer salt having a solid content of 30% (medium). (Degree of mol 65%)
Was obtained.

Production Examples 2 and 3 The polymers shown in Table 1 were obtained in the same manner as in Production Example 1 except that the neutralized salt and the degree of neutralization were changed as shown in Table 1 using the polymer (a ₀ ). Was.

Production Example 4 A glass reactor equipped with a stirrer, a dropping funnel, a nitrogen inlet, a thermometer and a reflux condenser was charged with 250 parts of methyl ethyl ketone, 98 parts of maleic anhydride and 0.8 parts of lauryl mercaptan. The gas phase of the vessel was replaced with nitrogen, and the temperature was raised to 80 ° C. Under stirring, a mixed solution of 75.9 parts of styrene and 40.4 parts of butyl acrylate and 40 parts of a 10% solution of azobisisobutyronitrile in 10% methyl ethyl ketone were added dropwise from separate containers over 3 hours. After completion of the dropwise addition, the mixture was maintained at the same temperature for 1 hour to obtain a copolymer (b ₀ ) having a conversion of 99.9%. Mw of the obtained polymer (b ₀ ) measured under GPC measurement conditions was 10,500, and Mw / Mn was 2.
80. After charging 750 parts of water, methyl ethyl ketone and a part of water are distilled off, and 30% sodium hydroxide 24
Maleic acid / styrene / butyl acrylate copolymer salt with a solid content of 30%, neutralized with 0.0 parts (neutralization degree 90 mol%)
An aqueous solution was obtained.

Production Examples 5 and 6 The polymers shown in Table 1 were obtained in the same manner as in Production Example 4 except that the neutralized salt and the degree of neutralization were changed as shown in Table 1 using the polymer (b ₀ ). Was.

Comparative Production Examples 1 and 2 The polymers shown in Table 1 were prepared in the same manner as in Production Example 1 except that the neutralized salt and the degree of neutralization were changed as shown in Table 1 using the polymer (a ₀ ). Obtained.

Comparative Production Example 3 Polymers shown in Table 1 were obtained in the same manner as in Comparative Production Example 1 except that the polymer (a ₀ ) was replaced with the polymer (b ₀ ).

Comparative Production Example 4 250 parts of methyl ethyl ketone, 166.6 parts of maleic anhydride and 0.8 parts of lauryl mercaptan were placed in a glass reactor equipped with a stirrer, a dropping funnel, a nitrogen inlet, a thermometer and a reflux condenser. Was charged, the gas phase of the vessel was replaced with nitrogen, and the temperature was raised to 80 ° C. Styrene 20.8 with stirring
And a mixture of 12.8 parts of butyl acrylate and a 10% solution of azobisisobutyronitrile in methyl ethyl ketone 4
0 parts were added dropwise over 3 hours from separate containers. After the completion of the dropwise addition, the mixture was maintained at the same temperature for 1 hour, and the polymerization rate was 99.9.
% Copolymer (c ₀ ) was obtained. Mw of the polymer (c ₀ ) measured under GPC measurement conditions was 12,000, and Mw / Mn was 2.75. After charging 750 parts of water, methyl ethyl ketone and a part of the water were distilled off, neutralized with 317.3 parts of 30% sodium hydroxide, and a styrene / butyl acrylate copolymer salt having a solid content of 30% (medium). Aqueous solution (compatibility: 70 mol%).

[0057]

[Table 1]

Examples 1 to 6 and Comparative Examples 1 to 4 100 parts of ion-exchanged water in a 230 ml container,
No. 6 or 0.5 part (solid content) of the dispersant of any of Comparative Production Examples 1 to 4 was uniformly dissolved, and 100 parts of magnesium hydroxide (average particle size: 1.0 μm) was added to each aqueous solution. Using a blade TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred and dispersed at 2,000 rpm for 5 minutes to obtain a 50% by weight aqueous magnesium hydroxide solution. The viscosity of the obtained aqueous dispersion immediately after production (after 1 hour) and after standing at 25 ° C. for 7 days was measured at 25 ° C. using a BL viscometer at rotor N.
o. The measurement was performed at 3 or 4 under the condition of 60 rpm. Table 2 shows the test results.

[0059]

[Table 2]

[0060]

The dispersant of the present invention, when used as a dispersant for an inorganic powder containing a hydroxide of an element of Groups 2 to 4 of the periodic table, has a high viscosity, a low viscosity and a good viscosity stability over time. The resulting aqueous dispersion is easy to transport, transport and handle. These aqueous dispersions can be effectively used in applications such as flue gas desulfurization, wastewater treatment, paints and papermaking.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 212/04 C08F 212/04 220/02 220/02 222/00 222/00 C08K 3/22 C08K 3 / 22 F term (reference) 4D077 AA07 AB20 AC05 BA02 CA12 DC27Y DC28Y DC42Y DC42Z DC59Y 4J002 AA061 BB041 BB141 BB171 BB181 BB191 BB231 BC011 BC041 BC081 DE0909 BC111 BC121 BC122 BE041 BG011 BG051 BG011 BG012 BG041 BG0121 DE106 DE136 DE146 DE156 GD00 GD03 HA07 4J100 AA02Q AA03Q AA04Q AA05Q AA06Q AA07Q AA15Q AA19Q AB00Q AB02Q AB03Q AB04Q AB07Q AB08Q AE18Q AJ01P AJ02P AJ08P AJ09P AL03Q AL04Q AL05Q AL08Q AL09Q AL36P AM15Q AM21Q AP01Q AR09Q AR10Q AR17Q AR22Q AS02Q AS03Q AS15Q AU21Q BA03P BA08Q BA15Q BA16Q BA20Q BA55Q BA56Q BC43Q CA04 CA31 HA31 HB36 HB37 HB39 HB43 HC42 HC43 HC44 HC45 HC46 HC47 HC63 HG23 JA15 JA19

Claims (11)

[Claims] 1. A dispersant for an inorganic powder (B) containing a hydroxide of an element of Groups 2 to 4 of the periodic table, wherein the dispersant is a carboxyl group-containing polymer (A1) or another acid. A group-containing (co) polymer (A2), the polymer (A1)
Is a partially neutralized product of a copolymer (A ₀ ) of 30 to 80 mol% of α, β-unsaturated carboxylic acid (a) and 20 to 70 mol% of another monomer (b); ) And (A2), wherein the total degree of neutralization of the acid groups is from 30 to 96 mol%. 2. (a) is (anhydrous) itaconic acid, (anhydrous)
The dispersant according to claim 1, wherein the dispersant is at least one selected from the group consisting of maleic acid, (anhydride) citraconic acid, fumaric acid, maleic acid half ester and fumaric acid half ester. 3. The dispersant according to claim 1, wherein (a) is maleic anhydride. 4. The dispersant according to claim 1, wherein the partially neutralized product is a neutralized product with an alkali metal and / or an organic amine. 5. An aromatic hydrocarbon monomer, (b) an aliphatic hydrocarbon monomer having 2 to 20 carbon atoms and 1 to 2 carbon atoms.
The dispersant according to any one of claims 1 to 4, wherein the dispersant is one or more monomers selected from the group consisting of alkyl (meth) acrylates having 36 alkyl groups. 6. The copolymer (A ₀ ) is converted to a sodium salt (100
% Neutralized) has a weight average molecular weight of 1,000 to 1
The dispersant according to any one of claims 1 to 5, wherein the dispersant is 0.00000. 7. The dispersant according to claim 1, wherein the inorganic powder (B) comprises only one or more hydroxides of Group 2 to 4 elements. 8. The method according to claim 1, wherein the hydroxide is magnesium hydroxide and / or
8. The dispersant according to claim 1, which is calcium hydroxide. 9. An inorganic powder (B) containing the dispersant according to claim 1 and one or more hydroxides selected from the group consisting of hydroxides of Group 2 to 4 elements. Aqueous dispersion containing 10. The aqueous dispersion according to claim 9, having a solid content of 10 to 80% by weight. 11. An absorbent for flue gas desulfurization, comprising the aqueous dispersion of claim 9 or 10.