JP2020182931A - Aqueous dispersant - Google Patents

Abstract

To provide an aqueous dispersant excellent in dispersibility of powder in water.SOLUTION: An aqueous dispersant includes a constitutional unit derived from (meth)acrylic branched ester, a constitutional unit derived from (alkoxy)polyalkylene glycol (meth)acrylates, and a constitutional unit derived from a (meth)acrylic acid. A percentage content of a constitutional unit including an aromatic ring is 3 mass% or less. The aqueous dispersant contains a copolymer with a weight-average molecular weight of 10000-80000.SELECTED DRAWING: None

Description

The present invention relates to an aqueous dispersant.

Slurried powders for electronic materials are used in the manufacture of electronic components such as multilayer ceramic capacitors. For example, a slurry composition of a dielectric ceramic powder is used as a material for forming a dielectric ceramic layer of a multilayer ceramic capacitor. With the increase in performance and miniaturization of electronic devices such as mobile phones and their electronic components, there is a demand for slurry compositions with improved handleability. For example, in order to reduce the size of a multilayer ceramic capacitor, it is necessary to make the dielectric ceramic layer thinner, and there is a demand for a slurry composition of a dielectric ceramic powder having improved dispersibility and workability.

A polycarboxylic acid-based (co) polymer is known as one of the powder dispersants.
In Patent Document 1, the formula CH ₂ = C (R ¹ ) COO (R ² O) _n R ³ (in the formula, R ¹ is a hydrogen atom or a methyl group, and R ² O is an oxyalkylene group having 2 to 4 carbon atoms. , N is an integer of 5 to 40, R ³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), a monomer represented by methacrylic acid or a salt thereof, and formula CH ₂ = C (R ⁴ ). Monomer represented by COOR ⁵ [In the formula, R ⁴ is a hydrogen atom or a methyl group, and R ⁵ is an alkyl group or (R ⁶ O) _m H (R ⁶ O) which may be substituted with a hydroxyl group having 1 to ⁵ carbon atoms. However, R ⁶ O represents an oxyalkylene group having 2 or 3 carbon atoms, and m represents an integer of 1 to 3). ] And (D) a powder made of a polyvalent metal salt of a copolymer having a weight average molecular weight in the range of 5000 to 100,000 obtained by copolymerizing other monomers at a predetermined ratio, and an inorganic powder. Powder cement dispersants are disclosed.

Patent Document 2 describes a method for producing a polymer compound by radical polymerization, which can efficiently reduce residual monomers, and the polymer compound is a dispersant, an emulsifier, a thickener, a pressure-sensitive adhesive, and a gelling agent. It is disclosed that it is used as such. Then, in the example, a polymer compound composed of stearyl methacrylate, methoxypolyethylene glycol (9 mol) methacrylate and methacrylic acid is disclosed.

Patent Document 3 describes a main chain composed of an addition polymer and a stabilizer unit composed of at least one C _1-4 alkoxypolyethylene or polyethylene-copropylene glycol acrylate or methacrylate, and 2,500 to An amphipathic copolymer having a weight average molecular weight of 20,000 is disclosed. Then, in Example 28 (Comparative Example), as the synthesis of the dispersant, styrene (106.9 g), 2-ethylhexyl acrylate (67.3 g), methacrylic acid (26.4 g) octane-1-thiol (13.2 g), It is disclosed that a mixture consisting of 2', 2'-azobis (2-methylbutyronitrile) and methyl ethyl ketone (88.4 g) was heated, and the residue from which the organic solvent had been removed was dissolved in water and neutralized with sodium hydroxide. Has been done.

Patent Document 4 describes a water-based ink for inkjet recording containing a pigment and water, a pigment dispersion resin containing an ethylene oxide chain, an anionic surfactant containing an ethylene oxide group, and an ethylene oxide group. A water-based ink for inkjet recording is disclosed, which comprises at least one of a nonionic surfactant containing the ink. Then, in the example, as a resin for pigment dispersion, styrene / methyl methacrylate / 2-ethylhexyl methacrylate / polyethylene glycol monomethacrylate (molecular weight 350) / methacrylic acid (20/20/20/20/20 mass ratio). A neutralized potassium hydroxide of a copolymer (number average molecular weight 13000) is disclosed.

Japanese Unexamined Patent Publication No. 2001-294463 Japanese Unexamined Patent Publication No. 2013-139502 Japanese Unexamined Patent Publication No. 6-100642 JP-A-2017-66392

For example, in the field of fine ceramics, which is used for electronic components, attempts have been made to realize miniaturization, high speed, low power consumption, high efficiency, and high capacity by controlling nanoscale microstructures. Therefore, there is a high demand for nano-dispersion technology for powders in water systems, and further improvement in the performance of dispersants is required.
The present invention provides an aqueous dispersant having excellent dispersibility of powder in an aqueous system.

In the present invention, a structural unit derived from (meth) acrylic acid branched ester [hereinafter referred to as structural unit (I)] and a structural unit derived from (alkoxy) polyalkylene glycol (meth) acrylate [hereinafter referred to as structural unit (II)]. And (meth) acrylic acid-derived structural unit [hereinafter referred to as structural unit (III)], the content of the structural unit containing the aromatic ring is 3% by mass or less, and the weight average molecular weight is 10,000 or more and 80,000 or less. The present invention relates to an aqueous dispersant containing a certain copolymer.
In addition, (meth) acrylic acid means acrylic acid or methacrylic acid, (alkoxy) means a structure containing or not containing an alkoxy group, and (meth) acrylate means acrylate or It means methacrylate (the same applies hereinafter).

Further, the present invention is a slurry composition containing the water-based dispersant of the present invention, a powder, and an water-based dispersion medium, wherein the water-based dispersant is 0.05% by mass in terms of solid content with respect to the powder. The present invention relates to a slurry composition containing at least 3.0% by mass or less.

The present invention also relates to a method for producing a slurry composition, which comprises a step of mixing the aqueous dispersant, the powder, and the aqueous dispersion medium of the present invention to disperse the powder.

According to the present invention, an aqueous dispersant having excellent dispersibility of powder in an aqueous system is provided. The dispersant of the present invention is a copolymer composed of specific structural units, and an excellent dispersion effect of powder (low viscosity, small particle size) in an aqueous system is exhibited with a small amount of addition.

<Aqueous dispersant>
The aqueous dispersant of the present invention has a structural unit (I) derived from (meth) acrylic acid branched ester, a structural unit (II) derived from (alkoxy) polyalkylene glycol (meth) acrylate, and a structural unit derived from (meth) acrylic acid. A copolymer containing (III) and a constituent unit containing an aromatic ring having a content of 3% by mass or less and a weight average molecular weight of 10,000 or more and 80,000 or less (hereinafter, may be referred to as a copolymer of the present invention). ) Is contained.

The reason why the powder can be satisfactorily dispersed in an aqueous system according to the present invention is not clear, but it is considered as follows. That is, in the copolymer of the present invention, the (meth) acrylic acid branched ester moiety is selectively adsorbed on the powder, an electrostatic repulsive force is exhibited at the (meth) acrylic acid moiety, and (alkoxy) polyalkylene glycol (alkoxy) polyalkylene glycol ( As a result of developing a steric repulsive force at the meta) acrylate site, it is considered that dispersion stabilization is efficiently achieved with a small amount of addition. Since the powder has conventionally hydrophobic properties, if the number of carbon atoms of the group containing the branched chain of the (meth) acrylic acid branched ester site to be selectively adsorbed is 6, for example, 6 or more, the powder is strongly adsorbed by the powder. It is considered to be. Further, if the weight average molecular weight of the copolymer is too small, it is considered that the steric repulsive force cannot be sufficiently exerted because the molecular size is small. If the weight average molecular weight is too large, the degree of freedom of conformation in which the copolymer is adsorbed on the powder is reduced, and it is considered that the electrostatic repulsive force and the three-dimensional repulsive force cannot be sufficiently exerted. Furthermore, when the content of aromatic rings such as styrene groups increases, the interaction of aromatic rings between the copolymers occurs and the apparent molecular weight increases, and the electrostatic repulsive force and the three-dimensional repulsive force are sufficiently exhibited. It is thought that it cannot be done. Since the copolymer of the present invention has a weight average molecular weight and a content of structural units including an aromatic ring within a predetermined range, electrostatic repulsive force and three-dimensional repulsive force are effectively exhibited, and the powder in an aqueous system can be used. It is presumed that the dispersibility can be improved.
However, these are estimates, and the present invention is not limited to these mechanisms.

The structural unit (I) is a structural unit derived from a (meth) acrylic acid branched ester (hereinafter, may be referred to as a monomer (I)).
Examples of the monomer (I) include (meth) acrylic acid branched chain ester and (meth) acrylic acid gel beester.

Examples of the (meth) acrylic acid branched chain ester include an ester of an alcohol having a hydrocarbon group having a tertiary or quaternary carbon and (meth) acrylic acid. The carbon number of the alcohol having a hydrocarbon group having a tertiary or quaternary carbon is preferably 3 or more, more preferably 6 or more, preferably 22 or less, and more preferably 13 or less. Examples of alcohols having a hydrocarbon group having a tertiary or quaternary carbon include isopropyl alcohol, isobutyl alcohol, pentaerythritol, 2-ethylhexyl alcohol, isodecyl alcohol, isotridecyl alcohol, and isostearyl alcohol.

Further, examples of the (meth) acrylic acid gel base ester include an ester of a secondary alcohol having no tertiary or quaternary carbon and (meth) acrylic acid. The number of carbon atoms of the secondary alcohol having no tertiary or quaternary carbon is preferably 6 or more, more preferably 8 or more, further preferably 10 or more, and further preferably 22 or less, further preferably 20 or less. Examples of the secondary alcohol having no tertiary or quaternary carbon include β-octyldodecyl alcohol.

Examples of the monomer (I) include a monomer represented by the following general formula (I).
CH ₂ = C (R ¹¹ ) -COOR ¹² (I)
[In the formula, R ¹¹ is a methyl group or a hydrogen atom, R ¹² is a branched hydrocarbon group having 3 or more carbon atoms, preferably 6 or more, and 22 or less, preferably 13 or less, preferably a branched alkyl group or branched. It shows a chain alkenyl group, more preferably a branched chain alkyl group. ]
The branched chain hydrocarbon groups of R ^12, a hydrocarbon group, and tertiary or quaternary hydrocarbon group secondary alcohol-derived no carbon derived from an alcohol having a hydrocarbon group having a tertiary or quaternary carbon Can be mentioned.

Examples of the monomer (I) include 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, and isostearyl (meth) acrylate. The monomer (I) is preferably 2-ethylhexyl (meth) acrylate.

The structural unit (II) is a structural unit derived from (alkoxy) polyalkylene glycol (meth) acrylate (hereinafter, may be referred to as monomer (II)).

The alkoxy group of the monomer (II) has, for example, 1 or more carbon atoms, preferably 8 or less, and more preferably 6 or less. The alkoxy group includes an unsaturated group. Examples of the polyalkylene glycol of the monomer (II) include polyethylene glycol. The average number of moles of alkylene oxide added to the polyalkylene glycol is preferably 4 or more, more preferably 6 or more, further preferably 8 or more, preferably 45 or less, further preferably 35 or less, still more preferably 25 or less. ..

Examples of the monomer (II) include (alkoxy) polyethylene glycol (meth) acrylate. From the viewpoint of reducing the viscosity of the aqueous slurry composition, the (alkoxy) polyethylene glycol (meth) acrylate has an ethylene oxide average addition molar number of preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and It is preferably 45 or less, more preferably 35 or less, still more preferably 25 or less.

Examples of the monomer (II) include a monomer represented by the following general formula (II).
R ^21- O- (AO) _n- CO-C (R ²² ) = CH ₂ (II)
[In the formula, R ²¹ is a hydrogen atom or a hydrocarbon group having 1 or more and 8 or less carbon atoms, preferably 6 or less, preferably an alkyl group or an alkenyl group, more preferably an alkyl group, and R ²² is a methyl group or a hydrogen atom, AO. Is 2 or more and 4 or less carbon atoms, preferably 2 or 3 alkyleneoxy groups, n is the average number of added moles, and is 4 or more, preferably 6 or more, more preferably 8 or more, and 45 or less, preferably 35 or less. , More preferably 25 or less. ]

The structural unit (III) is a structural unit derived from (meth) acrylic acid. The carboxy group of the structural unit (III) can take the form of an acid or a salt, but from the viewpoint of the affinity of the copolymer of the present invention with water, at least a part of the structural unit (III) is a salt. It is preferably in the form. That is, the carboxy group of the structural unit (III) is preferably a structural unit derived from (meth) acrylic acid, which is at least partially in the form of a salt. Examples of the salt include ammonium salt, quaternary ammonium salt, alkali metal salt and the like. Alkanol ammonium salts are formed by neutralization with alkanolamines.

(Meta) acrylic acid is a monomer of the following general formula (III). In the copolymer of the present invention, it is preferable that at least a part of the carboxy group COOH of the following monomer is a salt.
CH ₂ = C (R ³¹ ) -COOH (III)
[In the formula, R ³¹ represents a methyl group or a hydrogen atom. ]

The copolymer of the present invention is a copolymer containing the monomers of the general formulas (I), (II) and (III) as constituent monomers, and the content of the constituent units containing an aromatic ring is 3% by mass. It may be a copolymer having a weight average molecular weight of 10,000 or more and 80,000 or less.
Further, the copolymer of the present invention is a copolymer containing the monomers of the general formulas (I), (II) and (III) as constituent monomers, and is a monomer containing an aromatic ring among all the constituent monomers. It may be a copolymer having a ratio of 3% by mass or less and a weight average molecular weight of 10,000 or more and 80,000 or less.

From the viewpoint of reducing the viscosity of the aqueous slurry composition, the copolymer of the present invention preferably has the total of the structural units (I), (II) and (III) as 100% by mass, and the proportion of the structural unit (I). Is 10% by mass or more and 50% by mass or less, the proportion of the constituent unit (II) is 10% by mass or more and 80% by mass or less, and the proportion of the constituent unit (III) is 10% by mass or more and 80% by mass or less.
In the copolymer of the present invention, the total of the structural units (I), (II) and (III) is 100% by mass, and the ratio of the structural unit (I) is preferable from the viewpoint of reducing the viscosity of the aqueous slurry composition. Is 11% by mass or more, more preferably 12% by mass or more, further preferably 14% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less.
In the copolymer of the present invention, the total of the constituent units (I), (II) and (III) is 100% by mass, and the ratio of the constituent units (II) is preferable from the viewpoint of reducing the viscosity of the aqueous slurry composition. Is 15% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and preferably 75% by mass or less, more preferably 70% by mass or less, still more preferably 60% by mass or less.
In the copolymer of the present invention, the total of the constituent units (I), (II) and (III) is 100% by mass, and the ratio of the constituent units (III) is preferable from the viewpoint of reducing the viscosity of the aqueous slurry composition. Is 15% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, and preferably 75% by mass or less, more preferably 70% by mass or less, still more preferably 60% by mass or less.
In the present invention, unless otherwise specified, the amount ratio such as mass% or mass ratio of the constituent unit (III) is calculated by the amount converted into an acid compound.

The copolymer of the present invention has a content of a structural unit containing an aromatic ring of 3% by mass or less.
The structural unit containing an aromatic ring in the copolymer is a structural unit derived from a monomer containing an aromatic ring such as styrene, α-methylstyrene, 4-methylstyrene, and benzyl (meth) acrylate.
The content of the structural unit containing the aromatic ring is calculated for the structural unit derived from the monomer. For example, when the structural unit containing an aromatic ring is derived from styrene, the molecular weight of the structural unit containing an aromatic ring is 104. It is 176 in the case of benzyl methacrylate, 118 in the case of α-methylstyrene, and 118 in the case of 4-methylstyrene.

In the copolymer of the present invention, the content of the structural unit containing the aromatic ring is preferably 2% by mass or less, more preferably 1% by mass or less, still more preferably 0, from the viewpoint of reducing the viscosity of the aqueous slurry composition. It is more preferably 5% by mass or less and not containing a structural unit containing an aromatic ring, for example, a structural unit derived from styrene.

The copolymer of the present invention may contain monomers other than the monomers (I) to (III) and the monomer containing an aromatic ring. Examples of such monomers include α-olefins, sulfonic acid monomers, allyl alcohols, maleic anhydride, maleic acid, and itaconic acid.
The monomers other than the monomers (I) to (III) and the monomers containing an aromatic ring are preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and preferably 15% by mass or less, among all the constituent monomers. Is 0% by mass.

In the copolymer of the present invention, the total ratio of the structural units (I) to (III) in the total structural units is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more. , And preferably 100% by mass or less, and may be 100% by mass.

The weight average molecular weight (Mw) of the copolymer of the present invention is 10,000 or more, preferably 14,000 or more, more preferably 18,000 or more, and from the viewpoint of reducing the average particle size of the viscosity and dispersed particle size of the aqueous slurry composition. It is 80,000 or less, preferably 70,000 or less, and more preferably 60,000 or less. The weight average molecular weight of the copolymer is a value measured by GPC (gel permeation chromatography), and the details of the measurement conditions are as shown in Examples.

As one embodiment, the water-based dispersant of the present invention may be a liquid water-based dispersant and a liquid water-based dispersant containing water. As an embodiment of the aqueous dispersant of the present invention, there is a liquid aqueous dispersant containing the copolymer and water of the present invention.

The copolymer of the present invention preferably has at least a part in the form of a salt, and more preferably at least a part of the structural unit (III) in the form of a salt. From the viewpoint of improving dispersibility, the degree of neutralization of the copolymer of the present invention is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more. Here, in the present specification, the degree of neutralization is [molar equivalent of neutralized acid groups of the copolymer / molar equivalent of total acid groups that can be neutralized of the copolymer] × 100 (mol%). expressed.
As long as the above neutralization condition is satisfied, the copolymer of the present invention may be used in combination with different kinds of salts such as inorganic salts, ammonium salts or organic amine salts. At that time, the degree of neutralization or the degree of alkali excess when a plurality of salts of the copolymer of the present invention are used is not particularly specified, but is preferably 45 from the viewpoint of chemical decomposition resistance and odor resistance of the powder component. It is mol% or more, more preferably 55 mol% or more, further preferably 65 mol% or more, and preferably 120 mol% or less, more preferably 110 mol% or less, still more preferably 105 mol% or less. Here, the excess alkali in the present specification indicates that [molar equivalent of neutralized acid group of copolymer / molar equivalent of total acid group neutralized of copolymer] is larger than 1. It is a thing. The molar equivalent of the neutralized acid group of the copolymer is, in other words, the molar equivalent corresponding to the amount of alkali used for neutralization. The range in which the mol% is larger than 100 mol% is indicated as the degree of alkali excess.

When the aqueous dispersant of the present invention is a liquid composition, for example, a liquid composition containing water, the pH at 20 ° C. is preferably 4.5 from the viewpoint of chemical decomposition resistance and odor resistance of the powder component. As mentioned above, it is more preferably 5.0 or more, further preferably 5.5 or more, and preferably 11.0 or less, more preferably 10.0 or less, still more preferably 9.0 or less.

From the viewpoint of reducing the viscosity of the aqueous slurry composition, the aqueous dispersant of the present invention preferably contains the copolymer of the present invention in an amount of 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more. Then, it is preferably contained in an amount of 55% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less. The content of the copolymer of the present invention in the aqueous dispersant of the present invention can be determined, for example, from the amount of raw materials charged, or by measuring the amount of solids in the aqueous dispersant of the present invention. You can also do it.

In addition to the copolymer of the present invention, the aqueous dispersant of the present invention may contain, as an optional component, a nonionic surfactant, an anionic surfactant, an inorganic salt, an organic salt and the like.

In the aqueous dispersant of the present invention, the proportion of the copolymer of the present invention in the solid content is preferably 30% by mass or more, more preferably 35% by mass or more, still more preferably 40% by mass or more, and preferably 100. It may be mass% or less, more preferably 80 mass% or less, still more preferably 70 mass% or less. Here, as a measurement of the solid content of the aqueous dispersant, for example, about 1 g of a sample is placed in a 30 mL beaker, weighed with a last 4-digit balance to determine a mass 1, and allowed to stand in a dryer at 170 ° C. for 2 hours. After cooling in a desiccator for 30 minutes, weigh again with a last 4-digit balance to determine the mass 2. Then, a method of calculating the solid content from the difference between the mass 1 and the mass 2 can be mentioned.

The copolymer of the present invention can be produced in a reaction system containing water as a reaction medium. Then, after the reaction, the obtained mixture containing the copolymer of the present invention can be used as it is as the aqueous dispersant of the present invention.

The following methods can be mentioned as one form of the method for producing the aqueous dispersant of the present invention. A solvent such as isopropyl alcohol and ion-exchanged water is charged in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen introduction tube, a dropping funnel, etc., and the temperature is maintained after heating under a nitrogen stream. Next, each monomer mixed and dissolved in advance and a polymerization initiator, for example, an aqueous persulfate solution are added dropwise from different dropping funnels over a predetermined time to carry out a polymerization reaction. After the completion of the dropping, the mixture is aged for a predetermined time (a persulfate aqueous solution is added after a predetermined time has elapsed from the start of aging, for example, 15 minutes later) to complete the polymerization reaction. After completion of the reaction, the isopropyl alcohol is removed with an evaporator. Then, after adjusting the concentration with ion-exchanged water, while maintaining the temperature, for example, a neutralizing agent is added dropwise so that the pH becomes 6 to 7, and an aqueous dispersant is obtained. If the copolymer is to be obtained in the acid form, it is not neutralized. Although it depends on the monomer species, for example, in the case of unneutralized, the pH is about 2.

It is preferable to use a polymerization initiator in the polymerization reaction to easily initiate and accelerate the polymerization. Examples of the polymerization initiator include hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate and the like.
A chain transfer agent may be further added to the polymerization reaction. Examples of the chain transfer agent include isopropyl alcohol, 2-mercaptoethanol, mercaptomalic acid, mercaptoglycerol, 3-mercaptopropionic acid, butyl mercaptan, ammonium hypophosphite and the like.

From the viewpoint of easy control of the molecular weight of the polymer, as a polymerization method, a polymerization method in which each drug is charged into each dropping funnel and dropped at a predetermined time is preferable. The temperature at the time of polymerization and subsequent aging is preferably 75 ° C. or higher, more preferably 78 ° C. or higher, further preferably 81 ° C. or higher, and preferably 95 ° C. or lower, from the viewpoint of facilitating the reaction. It is preferably 92 ° C. or lower, more preferably 89 ° C. or lower.

Examples of the neutralizing agent added to neutralize the copolymer into a salt include sodium hydroxide, potassium hydroxide, lithium hydroxide, amine, ammonia, and ammonium compounds. Examples of the amine and ammonium compounds include diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, triethylamine, tributylamine, tetramethylammonium hydroxide, triethylmethylammonium hydroxide and the like. Ammonia can be used in aqueous solution.

The aqueous dispersant of the present invention produced as described above is excellent in reducing the viscosity of the slurry composition prepared by the powder and the aqueous dispersion medium and refining the dispersed powder. The aqueous dispersant of the present invention is suitable for dispersing various powders described later, particularly powders used as powders for electronic materials.

<Slurry composition and its production method>
By using the aqueous dispersant of the present invention, it is possible to obtain an aqueous slurry composition in which powder is dispersed in an aqueous dispersion medium. Therefore, in still other embodiments, the present invention can provide a slurry composition containing an aqueous dispersion medium, a powder, and the aqueous dispersant of the present invention. More specifically, the present invention is a slurry composition containing the water-based dispersant of the present invention, a powder, and an water-based dispersion medium, wherein the water-based dispersant is 0 in terms of solid content with respect to the powder. The present invention relates to a slurry composition containing 0.05% by mass or more and 3.0% by mass or less. The slurry composition of the present invention is a slurry composition containing the copolymer of the present invention, a powder, and an aqueous dispersion medium, and the copolymer of the present invention is 0 in terms of solid content with respect to the powder. It may be a slurry composition containing 0.05% by mass or more and 3.0% by mass or less.
The matters described in the aqueous dispersant of the present invention can be appropriately applied to the slurry composition of the present invention and the method for producing the same. Specific examples and preferable examples of the copolymer of the present invention are the same as those of the aqueous dispersant of the present invention.

The slurry composition of the present invention contains an aqueous dispersion medium. Examples of the aqueous dispersion medium include water or a mixed solution of water and a water-soluble organic solvent. Examples of water include distilled water, ion-exchanged water, ultrapure water and the like. Examples of the water-soluble organic solvent include ethyl alcohol, ethylene glycol and the like.

The slurry composition of the present invention contains powder. Examples of the powder include water-insoluble powder. For powder, water insolubility may mean that the amount dissolved in 100 g of water at 20 ° C. is 0.1 g or less. Powders include water-insoluble salts of cationic compounds such as carbonates, phosphates, titanium salts, silicates and manganese salts, zinc oxide, iron oxide, titanium oxide, alumina (aluminum oxide) and silica (oxidation). (Silicon), metal oxides such as magnesium oxide, zirconium oxide and cerium oxide, metal hydroxides such as nickel hydroxide, carbon black and silicon carbide and the like. Among these powders, the powder is preferably a metal oxide because it exhibits a slurry viscosity reducing effect. These powders can be used as powders for electronic materials in electronic components such as IC packages, wiring boards, insulators, sensors, electrodes, magnetic materials, semiconductors, capacitors, and optical fibers. Further, silica, cerium oxide powder and the like can be used as an abrasive powder. Further, manganate, nickel hydroxide and the like can be used as powders for primary or secondary batteries. Therefore, in another aspect, the present invention is an aqueous dispersant used for an electronic material powder, an abrasive powder, or a battery powder, an electronic material powder, an abrasive powder, or a battery powder. A method for dispersing the above, a slurry composition for a powder for an electronic material, a powder for an abrasive material, or a powder for a battery, and a method for producing the same can be provided. According to the present invention, for example, by improving the dispersibility of a powder slurry for electronic materials, the viscosity of the slurry can be reduced to improve workability, which can contribute to miniaturization of electronic components and improvement of productivity.

In the slurry composition of the present invention, the average particle size of the powder in the composition may be, for example, 80 nm or more, further 100 nm or more, 600 nm or less, and further 500 nm or less. Here, the average particle size of the powder can be measured using a laser scattering type particle size measuring device (Horiba Seisakusho Co., Ltd., LA-920, refractive index 1.25).

The content of the powder in the slurry composition of the present invention is not particularly limited, but from the viewpoint of improving drying efficiency and productivity, it is preferably 68% by mass or more, more preferably 72% by mass or more, still more preferably 76% by mass. % Or more. The upper limit value can be, for example, 85% by mass or less.

From the viewpoint of reducing the viscosity of the slurry composition, the slurry composition of the present invention contains the aqueous dispersant of the present invention in an amount of 0.05% by mass or more, preferably 0.07% by mass or more, in terms of solid content with respect to the powder. It is more preferably 0.1% by mass or more, and 3.0% by mass or less, preferably 1.0% by mass or less, and more preferably 0.4% by mass or less.

From the viewpoint of reducing the viscosity of the slurry composition, the slurry composition of the present invention preferably contains the copolymer of the present invention in terms of solid content with respect to the powder, preferably 0.05% by mass or more, more preferably 0.07% by mass. % Or more, more preferably 0.1% by mass or more, and preferably 3.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.4% by mass or less.

The slurry composition of the present invention has a viscosity at 25 ° C. of, for example, 60 mPa · s or more, further 65 mPa · s or more, further 70 mPa · s or more, and 190 mPa · s or less, further 180 mPa · s or less, further 165 mPa · s. It may be less than or equal to s. This viscosity can be measured at a rotor rotation speed of 60 rpm using a B-type viscosity measuring device TVB-10 manufactured by Toki Sangyo Co., Ltd.

The present invention relates to a method for producing a slurry composition, which comprises a step of mixing the aqueous dispersant, powder, and aqueous dispersion medium of the present invention to disperse the powder. The production method of the present invention may be a method for producing a slurry composition, which comprises a step of mixing the copolymer, the powder, and the aqueous dispersion medium of the present invention to disperse the powder.

As an embodiment of the method for producing a slurry composition of the present invention, for example, a method of adding powder to an aqueous solution in which the aqueous dispersant of the present invention is dissolved, stirring and mixing, or an aqueous dispersion medium and the present invention in the powder. Examples thereof include a method of adding the aqueous dispersant of the above, stirring and mixing. As a method of stirring and mixing, for example, a commonly used stirring device such as a homodisper, a homomixer, a ball mill, a bead mill, and a paint shaker can be used. The stirring temperature is preferably 20 ° C. or higher, more preferably 23 ° C. or higher, further preferably 25 ° C. or higher, and preferably 60 ° C. or lower from the viewpoint of easily mixing the aqueous dispersant of the present invention and the powder. , More preferably 50 ° C. or lower, still more preferably 40 ° C. or lower.

As another embodiment of the method for producing a slurry composition of the present invention, there is a production method in which coarse powder particles having a number average particle size of 10 μm or more are pulverized and slurried at the same time. Specific examples thereof include a method in which an aqueous dispersion medium and an aqueous dispersant of the present invention are added to coarse powder particles to form a slurry at the same time as pulverization. As a method of slurrying at the same time as pulverization, a commonly used stirring device such as a bead mill or a paint shaker can be used. At that time, the stirring temperature is preferably 20 ° C. or higher, more preferably 23 ° C. or higher, still more preferably 25 ° C. or higher, and preferably 25 ° C. or higher, from the viewpoint of easily mixing the aqueous dispersant of the present invention and the powder. It is 60 ° C. or lower, more preferably 50 ° C. or lower, still more preferably 40 ° C. or lower.

As another aspect, the present invention may provide a dispersion method including a step of dispersing powder in an aqueous dispersion medium using the aqueous dispersant of the present invention (hereinafter, also referred to as “dispersion method of the present invention”). .. The powder to be dispersed by the dispersion method of the present invention is as described above, and examples thereof include powders used as powders for electronic materials. Further, as described above, examples of the aqueous dispersion medium include water or a mixed solution of water and a water-soluble organic solvent such as ethyl alcohol or ethylene glycol, and water is preferable. Examples of water include distilled water, ion-exchanged water, ultrapure water and the like. According to the dispersion method of the present invention, a slurry composition having a reduced viscosity can be produced.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples thereof, but the present invention is not limited to the following Examples.

In Examples and Comparative Examples described later, the weight average molecular weight of the copolymer was measured by GPC (gel permeation chromatography). The specific conditions are as follows.
[Method for measuring weight average molecular weight of copolymer]
The weight average molecular weight of the copolymer was measured by GPC (gel permeation chromatography) under the following conditions.
Column: TSK PWXL + G4000PWXL + G2500PWXL (both manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Detector: RI or UV (210 nm)
Eluent: 0.2 mol / L phosphate buffer / acetonitrile (9/1)
Flow velocity: 1.0 mL / min
Injection volume: 0.1 mL
Standard: Monodisperse polyethylene glycol

[Preparation of Dispersant (Examples 1 to 14, Comparative Examples 1 to 11)]
The dispersants shown in Table 1 below (Examples 1 to 14 and Comparative Examples 1 to 11) were prepared as described below. In Table 1, methacrylic acid and acrylic acid having a monomer composition ratio (mass ratio) are shown in terms of acid-type compounds at the time of preparation. The symbols in Table 1 have the following meanings.
・ 2EHMA: 2-ethylhexyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ 2EHA: 2-Ethylhexyl acrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ MMA: Methyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ 2HyEtMA: 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.) ・ nBMA: Normal Butyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ LMA: Lauryl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
・ SMA: Stearyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
-MePEGnMA: Methoxypolyethylene glycol methacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., n is the number of moles of EO added and is the value shown in the table)
-MePEGnAA: Methoxypolyethylene glycol acrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., n is the number of moles of EO added and is the value shown in the table)
-PEGnMA: Polyethylene glycol methacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., n is the number of moles added by EO and is the value shown in the table)
・ MAA: Methacrylic acid (manufactured by Nippon Shokubai Co., Ltd.)
・ AA: Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.)
・ St: Styrene (manufactured by Idemitsu Kosan Co., Ltd.)
・ NH ₃ : Ammonia salt using 28% by mass ammonia aqueous solution ・ Na: Sodium salt using 48% by mass sodium hydroxide aqueous solution (manufactured by Shinetsu Chemical Industry Co., Ltd.) ・ K: Potassium hydroxide (manufactured by Kimura Sangyo Co., Ltd., Potassium salt using reagent special grade) ・ MEA: Monoethanolammonium salt using monoethanolamine (manufactured by Nippon Catalyst Co., Ltd.) ・ DEA: Diethanolammonium salt using diethanolamine (manufactured by Nippon Catalyst Co., Ltd.) ・ TEA: Triethanol Triethanolammonium salt using amine (manufactured by Nippon Catalyst Co., Ltd.) ・ TMAH: Tetramethylammonium salt using 25% by mass tetramethylammonium hydroxide (manufactured by Showa Denko Co., Ltd.)

(1) Example 1
115.5 g of isopropyl alcohol (manufactured by Mitsui Chemicals, Inc.) and 100.0 g of ion-exchanged water were charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen introduction tube, and a dropping funnel. Next, after heating to 85 ° C. under a nitrogen stream, 18.0 g of 2-ethylhexyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.) and methoxypolyethylene glycol (EO 13 mol) methacrylate were previously dissolved and mixed while maintaining this temperature. (Manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 84.0 g, methacrylic acid (manufactured by Mitsubishi Chemical Industry Co., Ltd.) 18.0 g and 2.7 mass% 3-mercaptopropionic acid aqueous solution (manufactured by Tokyo Chemical Industry Co., Ltd.) 60.0 g and 2 29.1 g of a mass% ammonium persulfate aqueous solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added dropwise from separate dropping funnels over 2 hours to carry out a polymerization reaction. After completion of the dropping, the mixture was aged at 85 ° C. for 5 hours (2.5 g of a 2 mass% ammonium persulfate aqueous solution was added 15 minutes after the start of aging) to complete the polymerization reaction. After completion of the reaction, isopropyl alcohol was removed by an evaporator at 80 ° C. After adjusting the concentration with ion-exchanged water, 9.1 g of a 28 mass% aqueous ammonia solution (manufactured by Sigma Aldrich Co., Ltd., special grade reagent) was added dropwise to neutralize the pH while maintaining about 40 ° C. A reaction mixture containing an ammonium salt of the copolymer was obtained. The degree of neutralization was 72 mol% (against methacrylic acid). Further, ion-exchanged water was added to adjust the solid content concentration (copolymer concentration) to 40% by mass. The weight average molecular weight (Mw) was measured by GPC, and the Mw of the copolymer was 20500. This reaction mixture contained a copolymer which is an ammonium salt and water, and this was used as a dispersant.

(Examples 2 to 14, Comparative Examples 1 to 11)
An aqueous dispersant containing a copolymer consisting of the monomer composition ratio, Mw, neutralizing salt or acid-type compound shown in Table 1 was prepared in the same manner as in Example 1. The solid content concentration of the dispersant is the same value as that of the dispersant of Example 1. In addition, the neutralized product has the same degree of neutralization as the dispersant of Example 1. Further, in Example 14, an acid-type copolymer was used as a dispersant without neutralization.

[Preparation and evaluation of slurry composition]
Using the dispersants of Examples 1 to 14 and Comparative Examples 1 to 11, a slurry composition was prepared as follows, and each of the obtained slurry compositions was tested.

Dispersibility test of each dispersant 117 g of alumina powder (AES-12 manufactured by Sumitomo Chemical Co., Ltd.) having an average particle size of 400 nm in 500 mL of a disposer beaker, and 0.1 using the dispersant of Example or Comparative Example as a copolymer. Add mass% or 0.3% by mass (against alumina powder, solid content equivalent) and ion-exchanged water, and stir with a homodisper manufactured by Primix Co., Ltd. (2500 rpm x 2 minutes), and the powder content is 78 mass. % Slurry composition was prepared.
The B viscosity of the obtained slurry composition at 25 ° C. was measured at a rotor rotation speed of 60 rpm using a B-type viscosity measuring device TVB-10 manufactured by Toki Sangyo Co., Ltd.
Further, the average particle size of the dispersed powder of the obtained slurry composition was measured by ionizing a laser scattering type particle size measuring device (Horiba Seisakusho Co., Ltd., LA-920, refractive index 1.25, 78% by mass). It was measured using (diluted 100-fold with exchanged water).

As shown in the above table, the slurry compositions using the dispersants of Examples 1 to 14 were confirmed to have a lower viscosity than those using the dispersants of Comparative Examples 1 to 11, and were excellent in dispersibility. ..
Further, as shown in the above table, the slurry composition using the dispersants of Examples 1 to 14 has a finer average particle size of the powder to be dispersed than the slurry composition using the dispersants of Comparative Examples 1 to 11. It was excellent in dispersibility.

Claims (8)

Constituent units derived from (meth) acrylic acid branched ester [hereinafter referred to as structural unit (I)] and structural units derived from (alkoxy) polyalkylene glycol (meth) acrylate [hereinafter referred to as structural unit (II)] and (meth). A copolymer containing a structural unit derived from acrylic acid [hereinafter referred to as a structural unit (III)], having a content of the structural unit containing an aromatic ring of 3% by mass or less, and having a weight average molecular weight of 10,000 or more and 80,000 or less. A water-based dispersant containing. In the copolymer, the total of the structural units (I), (II) and (III) is 100% by mass, the ratio of the structural unit (I) is 10% by mass or more and 50% by mass or less, and the ratio of the structural unit (II). Is 10% by mass or more and 80% by mass or less, and the ratio of the constituent unit (III) is 10% by mass or more and 80% by mass or less.
The aqueous dispersant according to claim 1. The aqueous dispersant according to claim 1 or 2, wherein the (alkoxy) polyalkylene glycol (meth) acrylate is (alkoxy) polyethylene glycol (meth) acrylate, and the average number of moles of ethylene oxide added to the polyethylene glycol is 4 or more and 45 or less. .. The aqueous dispersant according to any one of claims 1 to 3, wherein the (meth) acrylic acid branched ester is 2-ethylhexyl (meth) acrylate. A slurry composition containing the aqueous dispersant according to any one of claims 1 to 4, a powder, and an aqueous dispersion medium, wherein the aqueous dispersant is 0.05% by mass in terms of solid content with respect to the powder. A slurry composition containing at least 3.0% by mass or less. The slurry composition according to claim 5, wherein the content of the powder is 68% by mass or more. The slurry composition according to claim 5 or 6, wherein the powder is a metal oxide. A method for producing a slurry composition, which comprises a step of mixing the aqueous dispersant, the powder, and the aqueous dispersion medium according to any one of claims 1 to 4 to disperse the powder.