JP2014070003A - Inorganic composite for inorganic powder dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an inorganic composite for inorganic powder dispersion, capable of achieving excellent dispersibility in a simple process; a method for producing the inorganic composite for inorganic powder dispersion; a method for producing a slurry composition; and the slurry composition.SOLUTION: An inorganic composite used for inorganic powder dispersion includes: an inorganic powder; and a coating layer on a surface of the inorganic powder. The coating layer includes: an inner layer made of a polyvinyl acetal resin (a1) having a hydroxyl group amount of 20-40 mol%; and an outer layer made of a polyvinyl acetal resin (a2) having a hydroxyl group amount of 28-60 mol%. The polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) have a relation of following formula (1). In the formula (1), X represents a hydroxyl group amount (mol%) of the polyvinyl acetal resin (a1), and Y represents a hydroxyl group amount (mol%) of the polyvinyl acetal resin (a2).

Description

The present invention relates to an inorganic composite for dispersing an inorganic powder that can realize excellent dispersibility by a simple process. Moreover, it is related with the manufacturing method of this inorganic composite for inorganic powder dispersion | distribution, the manufacturing method of a slurry composition, and a slurry composition.

Polyvinyl acetal resin is excellent in toughness, film-forming properties, inorganic pigments, dispersibility of organic powders, adhesion to coated surfaces, etc. And conductive paste, ink, paint, baking enamel, wash primer, etc.

In particular, a multilayer ceramic capacitor is generally manufactured through the following steps.
First, a ceramic raw material powder is added to a binder resin such as a polyvinyl butyral resin and mixed uniformly to obtain a slurry composition. The obtained slurry composition is applied to the support surface subjected to the mold release treatment. This is heated to remove volatile components such as a solvent, and then peeled off from the support to obtain a ceramic green sheet. Next, on the obtained ceramic green sheet, a plurality of sheets of conductive paste containing ethyl cellulose, polyvinyl butyral resin, etc. applied as a binder resin are alternately stacked, heated and pressed to produce a laminate, After performing the degreasing treatment, a multilayer ceramic capacitor is obtained through a step of sintering an external electrode on the end face of the fired ceramic product obtained by firing.

In recent years, there has been a demand for further downsizing and higher capacity of multilayer ceramic capacitors, and further multilayering and thinning have been studied. In such multilayer ceramic capacitors, a thin film of a ceramic green sheet is considered. Therefore, ceramic powders having a small particle diameter are demanded.

Generally, as a method of dispersing ceramic powder or the like in a slurry composition, as described in Patent Document 1, an inorganic dispersion composed of an inorganic powder, an organic solvent, etc. is prepared on the one hand, and a binder resin is dissolved on the other hand. A method of mixing the inorganic dispersion and the resin solution after preparing the prepared resin solution is used.
However, such a method has a problem that unless the mixed solution is stirred for a long time, the ceramic powder is not sufficiently dispersed, and stirring requires excessive energy and time.
As a method for ensuring the dispersibility of the ceramic powder in the slurry composition, as described in Patent Document 2, a method of adding a dispersant is also used. However, in such a method, when the compatibility with the binder resin is poor, there is a problem that the dispersibility is deteriorated or the dispersibility is lowered during long-term storage.
In order to solve the problem, Patent Document 3 describes a method in which an acetalization reaction is performed after a powder is dispersed in a polyvinyl alcohol solution. However, such a method has a problem that when the powder is extremely small, the powder cannot be finely dispersed in the polyvinyl alcohol.

On the other hand, dispersibility is also improved by using polyvinyl acetal resin as a dispersant, but when a ceramic green sheet is produced using such a slurry composition, ceramic green In the process of heat-pressing the sheet, there is a problem that thermal deformation is likely to occur and the ceramic green sheet is distorted. As a result, there is a problem that the electrode pattern of the obtained multilayer ceramic capacitor does not have a desired shape and leads to a short circuit or the like.

JP 2005-139034 A JP-A-6-325971 Japanese Patent No. 4828277

An object of this invention is to provide the inorganic composite for inorganic powder dispersion which can implement | achieve the outstanding dispersibility by a simple process in view of the said present condition. Moreover, it aims at providing the manufacturing method of this inorganic composite for inorganic powder dispersion | distribution, the manufacturing method of a slurry composition, and a slurry composition.

式（１）中、Ｘはポリビニルアセタール樹脂（ａ１）の水酸基量（モル％）、Ｙはポリビニルアセタール樹脂（ａ２）の水酸基量（モル％）を表す。
以下に本発明を詳述する。 This invention is an inorganic composite used for dispersion | distribution of inorganic powder, Comprising: The surface of an inorganic powder has a coating layer, The said coating layer is polyvinyl acetal resin (a1) whose hydroxyl amount is 20-40 mol% And an outer layer made of a polyvinyl acetal resin (a2) having a hydroxyl group content of 28 to 60 mol%. The polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are represented by the following formula (1). And an inorganic composite for dispersing an inorganic powder.

In formula (1), X represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a1), and Y represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a2).
The present invention is described in detail below.

The inventors of the present invention used an inorganic composite for dispersing an inorganic powder having a coating layer having a two-layer structure made of a polyvinyl acetal resin having a predetermined amount of hydroxyl group and polymerization degree. It has been found that excellent dispersibility can be realized by a simple process without using it separately.
In addition, such an inorganic composite for dispersing an inorganic powder is such that the inorganic powder and the polyvinyl acetal resin are firmly bonded to each other, so that the polyvinyl acetal resin easily stays around the inorganic powder. In this case, it was found that thermal deformation hardly occurs, and the present invention has been completed.

The inorganic composite for inorganic powder dispersion described in the present invention has a coating layer on the surface of the inorganic powder.
The inorganic powder is not particularly limited, and examples thereof include conductive powder, magnetic powder, ceramic powder, and glass powder.

The conductive powder is not particularly limited as long as it exhibits sufficient conductivity, and examples thereof include powder made of nickel, palladium, platinum, gold, silver, copper, alloys thereof, and the like. These conductive powders may be used alone or in combination of two or more.

The magnetic powder is not particularly limited, for example, ferrites such as manganese zinc ferrite, nickel zinc ferrite, copper zinc ferrite, barium ferrite and strontium ferrite, metal oxides such as chromium oxide, metal magnetic materials such as cobalt, amorphous Examples include magnetic materials. These magnetic powders may be used alone or in combination of two or more.

The ceramic powder is not particularly limited. For example, a powder made of alumina, zirconia, aluminum silicate, titanium oxide, zinc oxide, barium titanate, magnesia, sialon, spinemullite, silicon carbide, silicon nitride, aluminum nitride, or the like. Is mentioned. Especially, it is preferable to consist of the same component as the ceramic powder contained in the ceramic green sheet to be used. These ceramic powders may be used alone or in combination of two or more.

The glass powder is not particularly limited. For example, lead oxide-boron oxide-silicon oxide-calcium oxide glass, zinc oxide-boron oxide-silicon oxide glass, lead oxide-zinc oxide-boron oxide-silicon oxide glass. Etc. These glass powders may be used alone or in combination of two or more. Moreover, you may use aluminum oxide etc. together in the range which does not impair the objective of this invention.

The average particle size of the inorganic powder is preferably 0.01 to 10 μm.
When the average particle size is less than 0.01 μm, dispersibility becomes insufficient, and the resin may not be sufficiently adsorbed on the surface of the inorganic powder. When the average particle size exceeds 10 μm, the mass of the inorganic powder becomes large, and adhesion is caused. The effect of the polyvinyl acetal resin may not be sufficiently exhibited.

The inorganic composite for dispersing inorganic powder of the present invention comprises an inner layer composed of a polyvinyl acetal resin (a1) having a hydroxyl group content of 20 to 40 mol% and a polyvinyl acetal resin (a2) having a hydroxyl group content of 28 to 60 mol%. And a coating layer having an outer layer.

In the present invention, the coating layer is formed of polyvinyl acetal resins having different properties such as a polyvinyl acetal resin (a1) and a polyvinyl acetal resin (a2).
The above two types of polyvinyl acetal resins have the property of easily loosening the aggregates of inorganic powder and the property of easily adhering to the surface of the inorganic powder, so the synergistic effect of these two dramatically improves the dispersibility of the inorganic powder. It becomes possible to do.
In addition, the polyvinyl acetal resin (a1) is covered with the polyvinyl acetal resin (a2) so that the polyvinyl acetal resin (a1) is not easily detached, and the polyvinyl acetal resin and the inorganic powder are more firmly bonded to each other, thereby further increasing the strength of the sheet. Can be made.

The said coating layer has an inner layer which consists of polyvinyl acetal resin (a1) whose hydroxyl amount is 20-40 mol%. By comprising the polyvinyl acetal resin (a1), the polyvinyl acetal resin (a1) penetrates into the surface of the inorganic powder more quickly, and the aggregates of the inorganic powder are easily loosened.

The minimum of the amount of hydroxyl groups of the said polyvinyl acetal resin (a1) is 20 mol%, and an upper limit is 40 mol%. When the amount of the hydroxyl group is less than 20 mol%, the affinity to the surface of the inorganic powder is almost eliminated and the surface does not adhere to the surface of the inorganic powder, and does not contribute to the improvement of dispersibility. Adhesion to the surface becomes excessive, adheres only to the surface of the inorganic powder aggregate, and it becomes difficult to loosen. A preferable lower limit of the hydroxyl group content is 26 mol%, and a preferable upper limit is 38 mol%.

The preferable lower limit of the polymerization degree of the polyvinyl acetal resin (a1) is 20, and the preferable upper limit is 450. If the degree of polymerization is less than 20, it may be difficult to obtain industrially. When the said polymerization degree exceeds 450, it may become difficult to osmose | permeate the surface of an inorganic powder by the bulk height of polyvinyl acetal resin (a1) itself. A more preferable lower limit of the degree of polymerization is 100, and a more preferable upper limit is 300.

The said coating layer has an outer layer which consists of polyvinyl acetal resin (a2) whose amount of hydroxyl groups is 28-60 mol%. By containing the polyvinyl acetal resin (a2), the polyvinyl acetal resin (a2) adheres more strongly to the surface of the inorganic powder, and long-term storage stability becomes possible.

The minimum of the amount of hydroxyl groups of the said polyvinyl acetal resin (a2) is 28 mol%, and an upper limit is 60 mol%. When the amount of the hydroxyl group is less than 28 mol%, the affinity to the surface of the inorganic powder is insufficient, the adhesion amount is insufficient and does not contribute to the improvement of dispersibility, and when it exceeds 60 mol%, the solubility in the solvent is increased. Insufficient, the molecules may not spread sufficiently and may not adhere to the surface of the inorganic powder. A preferable lower limit of the amount of the hydroxyl group is 42 mol%, and a preferable upper limit is 55 mol%.

The preferable lower limit of the degree of polymerization of the polyvinyl acetal resin (a2) is 200, and the preferable upper limit is 600. When the degree of polymerization is less than 200, the bulkiness is insufficient, and it may be difficult to keep the distance between the inorganic powders moderate. When the degree of polymerization exceeds 600, the cohesive force becomes too high, and it may be difficult to develop sufficient dispersibility. The more preferable lower limit of the degree of polymerization is 320, and the more preferable upper limit is 450.

The polyvinyl acetal resin (a2) preferably has an anionic group.
By having the anionic group, the polyvinyl acetal resin (a2) can easily adhere to the surface of the inorganic powder, and the dispersibility of the inorganic powder can be improved.

The anionic group is not particularly limited as long as it is an anionic modifying group, and examples thereof include a carboxyl group, a sulfonic acid group, and a phosphoric acid group.

The preferable lower limit of the degree of modification of the anionic group is 0.1 mol%, and the preferable upper limit is 2 mol%.
When the degree of modification of the anionic group is less than 0.1 mol%, the polyvinyl acetal resin (a2) is less likely to adhere to the surface of the inorganic powder, and may not contribute to improvement in dispersibility. If it exceeds 1, attractive interaction may work between the polyvinyl acetal resins (a2), and it may be difficult to adhere to the surface of the inorganic powder. A more preferable lower limit of the degree of modification is 0.2 mol%, and a more preferable upper limit is 1 mol%.
The degree of modification is derived from a methine group to which a carboxy group is bonded by dissolving a polyvinyl acetal resin (a2) in DMSO-d ₆ (dimethyl sulfoxide) and measuring a ¹³ C-NMR spectrum. It can be calculated from the peak area and the peak area derived from the methine group of the acetalized portion.

The polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) have a relationship represented by the following formula (1).

式（１）中、Ｘはポリビニルアセタール樹脂（ａ１）の水酸基量（モル％）、Ｙはポリビニルアセタール樹脂（ａ２）の水酸基量（モル％）を表す。

In formula (1), X represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a1), and Y represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a2).

By having the above relationship between the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2), a difference in adhesion to the surface of the inorganic powder is generated, and the aggregate of the inorganic powder is effectively loosened, This state can be maintained.
In Formula (1), the upper limit of Y-X is not particularly limited, but when it is far away, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are difficult to be compatible, and the sheet strength is reduced. Therefore, 7 to 30 is preferable, and 9 to 15 is more preferable.

In the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2), the ratio of the portion acetalized with acetaldehyde and the portion acetalized with butyraldehyde is preferably 30/70 to 95/5. In the portion acetalized with the acetaldehyde, the length of the hydrocarbon group due to the aldehyde is shortened and the steric hindrance is lowered, so that the hydroxyl group may be easily adsorbed to the inorganic powder. Therefore, by setting the portion acetalized with acetaldehyde to be 30/70 or more, the dispersibility of the inorganic powder is improved and high dispersibility can be maintained over a long period of time. More preferably, the ratio of the portion acetalized with acetaldehyde and the portion acetalized with butyraldehyde is 40/60 to 80/20.

In the said polyvinyl acetal resin (a1) and polyvinyl acetal resin (a2), the minimum with preferable content of an acetyl unit is 0.5 mol%, and a preferable upper limit is 20 mol%. When the content of the acetyl unit is less than 0.5 mol%, the polyvinyl acetal intermolecular distance is decreased, and the intermolecular hydrogen bonding force is increased, which may make it difficult to adhere to the surface of the inorganic powder. If it exceeds 20 mol%, the polyvinyl acetal intermolecular distance increases and the intermolecular hydrogen bonding force decreases, so that sufficient strength may not be obtained.

The polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are preferably polyvinyl acetal resins obtained by acetalizing a polyvinyl alcohol resin with an aldehyde.

The acetalization method is not particularly limited, and a conventionally known method can be used. For example, an aqueous solution of polyvinyl alcohol, an alcohol solution, a water / alcohol mixed solution, a dimethyl sulfoxide (DMSO) solution in the presence of an acid catalyst. Examples thereof include a method of adding various aldehydes.

The aldehyde used for the acetalization is not particularly limited. For example, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal, glutaraldehyde, benzaldehyde 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. Among them, it is preferable to use acetaldehyde and butyraldehyde alone or to use acetaldehyde and butyraldehyde in combination.

The acid catalyst is not particularly limited, and either an organic acid or an inorganic acid can be used. Examples thereof include acetic acid, paratoluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid.

In order to stop the acetalization reaction, neutralization with an alkali is preferably performed. It does not specifically limit as said alkali, For example, sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, potassium hydrogencarbonate etc. are mentioned.
Moreover, it is preferable to wash | clean the polyvinyl acetal resin obtained using water etc. before and after the said neutralization process. In order to prevent impurities contained in the cleaning water from being mixed, it is more preferable to perform the cleaning with pure water.

The polyvinyl alcohol resin is preferably a polyvinyl alcohol resin obtained by saponifying a polymer of vinyl ester such as vinyl formate, vinyl acetate, vinyl propionate or vinyl pivalate. From the economical viewpoint, the vinyl ester is preferably vinyl acetate.

The polyvinyl alcohol resin is more preferably a polyvinyl alcohol resin obtained by saponifying the copolymer of the vinyl ester and the α-olefin.
Examples of the α-olefin include ethylene, propylene, isopropylene, butylene, isobutylene, pentylene, hexylene, cyclohexylene, cyclohexylethylene, and cyclohexylpropylene. Of these, ethylene is preferable.
Further, as the polyvinyl alcohol resin, a terminal-modified polyvinyl alcohol resin obtained by copolymerizing the vinyl ester and ethylene in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid, and then saponifying is then used. May be.

When the polyvinyl alcohol resin is copolymerized, the content of the α-olefin is preferably 1 mol% at a preferable lower limit and 20 mol% at a preferable upper limit. When the content of the α-olefin is less than 1 mol%, the effect of adding the α-olefin may not be obtained. When the content of the α-olefin exceeds 20 mol%, the solubility of the obtained polyvinyl alcohol resin in water decreases, making it difficult to perform the acetalization reaction, or the hydrophobicity of the obtained polyvinyl acetal resin. May become too strong and the solubility in organic solvents may decrease.

The polyvinyl alcohol resin is a polyvinyl alcohol resin obtained by copolymerizing other ethylenically unsaturated monomers in addition to the vinyl ester and the α-olefin within a range not impairing the effects of the present invention. There may be.
Examples of the other ethylenically unsaturated monomers include acrylic acid, methacrylic acid, (anhydrous) fumaric acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, and trimethyl. -(3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, Examples include vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate, and sodium allyl sulfonate.

When the polyvinyl alcohol resin is copolymerized, the content of the other ethylenically unsaturated monomers is preferably 1 mol% at the preferred lower limit and 30 mol% at the preferred upper limit. If the content of the other ethylenically unsaturated monomer is less than 1 mol%, the effect of adding the other ethylenically unsaturated monomer may not be obtained. When content of the said other ethylenically unsaturated monomer exceeds 30 mol%, properties, such as adhesiveness of a polyvinyl acetal resin obtained, coating-film strength, and thermal decomposability, may fall.

The polyvinyl alcohol resin has a preferred lower limit of the saponification degree of 80 mol%. If the degree of saponification is less than 80 mol%, the solubility of the resulting polyvinyl alcohol in water may be reduced, making it difficult to carry out the acetalization reaction. If the amount is small, it may be difficult to proceed with the acetalization reaction itself.

In the inorganic composite for dispersing an inorganic powder of the present invention, the total amount of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) is preferably 0.1 parts by weight with respect to 100 parts by weight of the inorganic powder. The preferred upper limit is 20 parts by weight. When the content is less than 0.1 part by weight, the polyvinyl acetal resins (a1) and (a2) may not be sufficiently adsorbed on the surface of the inorganic powder, and the dispersibility of the inorganic powder may be insufficient. When the said content exceeds 20 weight part, a viscosity will become high too much and a handleability may worsen. A more preferred lower limit is 0.5 parts by weight, and a more preferred upper limit is 5 parts by weight.
The weight ratio of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) constituting the mixed polyvinyl acetal resin (A) is preferably 2: 8 to 8: 2. By setting it within the above range, the effects of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) can be sufficiently exhibited.

A preferable lower limit of the thickness of the entire coating layer is 0.1 nm, and a preferable upper limit is 1000 nm. When the thickness is less than 0.1 nm, the binder may not be sufficiently removed when the binder is added, and the ceramic may aggregate. When the thickness exceeds 1000 nm, the ceramic is adsorbed. The ceramic may not move easily due to the dispersant, and may not be sufficiently dispersed. A more preferable lower limit of the thickness of the entire coating layer is 1 nm, and a more preferable upper limit is 200 nm.
The thickness of the coating layer can be measured by a dry density measurement method.
Moreover, it is preferable that the film thickness ratio of the inner layer which comprises the said coating layer, and an outer layer is 2: 8-8: 2. By setting it within the above range, the effects of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) can be sufficiently exhibited.

The coating layer may contain, for example, an acrylic resin such as polymethyl methacrylate, a cellulose resin such as ethyl cellulose, and a resin such as polyethylene oxide.

The average particle diameter of the inorganic composite for dispersing inorganic powder of the present invention is preferably 0.02 to 10 μm.
When the average particle size is less than 0.02 μm, the surface area becomes too large, and when added to a solvent, the dispersibility of the particles may be insufficient. When the average particle size exceeds 10 μm, the mass of the particles is large. The effect of adhering the resin may not be sufficiently obtained.
In addition, the said average particle diameter can be measured with a laser diffraction type particle size distribution measuring apparatus (Shimadzu Corporation make, SALD-2300) etc., for example.

As a method for producing the inorganic composite for dispersing inorganic powder of the present invention, for example, inorganic powder, polyvinyl acetal resin (a1) and coating organic solvent are added and mixed, and then polyvinyl acetal resin (a2) is added and mixed. The method of performing the process of producing an inorganic dispersion liquid by doing and the process of drying the said organic solvent for coating | cover is mentioned.

In the step of preparing the inorganic dispersion, it is preferable to add 0.1 to 20 parts by weight of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) with respect to 100 parts by weight of the inorganic powder. If the addition amount is less than 0.1 parts by weight, the amount of the adhering resin may be insufficient, so that dispersibility may be insufficient. If the addition amount exceeds 20 parts by weight, the adhering resin In some cases, the amount is too large and the strength is insufficient.

The organic solvent for coating is not particularly limited, and organic solvents generally used in slurry compositions can be used. For example, ketones such as acetone, methyl ethyl ketone, dipropyl ketone, and diisobutyl ketone, methanol , Alcohols such as ethanol, isopropanol and butanol, aromatic hydrocarbons such as toluene and xylene, methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, Esters such as ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, 2-ethylhexyl butyrate, terpineol, dihydroterpineol, terpineol acetate, dihydrotel Ne terpineol and its derivatives such as all-acetate. These organic solvents may be used independently and 2 or more types may be used together.

The inorganic composite for dispersing inorganic powder of the present invention is used for dispersion of inorganic powder. In particular, the inorganic composite for dispersing inorganic powder of the present invention is added to and mixed with an organic solvent for inorganic dispersion to produce an inorganic dispersion. Adding a polyvinyl acetal resin for a binder and an organic solvent for a resin solution, mixing the resin solution to prepare a resin solution, and adding the resin solution to the inorganic dispersion; By using a polymer having a polymerization degree of 800 to 4000, excellent dispersibility can be realized by a simple process.
The method for producing such a slurry composition is also one aspect of the present invention.

In the method for producing the slurry composition of the present invention, the step of adding the inorganic composite for dispersing an inorganic powder of the present invention to an organic solvent for inorganic dispersion to prepare an inorganic dispersion, the polyvinyl acetal resin for binder and the resin solution An organic solvent is added and mixed to prepare a resin solution, and a resin solution is added to the inorganic dispersion.
In the present invention, in the step of preparing the inorganic dispersion, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) of the inorganic composite for dispersing an inorganic powder have a role as a dispersant, Once the solvent is dried to produce an inorganic composite, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are more firmly bound to the inorganic powder than when the inorganic powder composite is not prepared. Thus, in the process of producing the inorganic dispersion liquid, the polyvinyl acetal resin (a1) and the polyvinyl acetal are obtained by acting as a dispersant in a state where the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are more firmly bound. The resin (a2) is more firmly attached to the surface of the inorganic powder, and as a result, the dispersibility of the inorganic powder can be improved. Then, even if the resin solution containing the polyvinyl acetal resin for the binder is added to the inorganic dispersion, the polyvinyl acetal resin for the binder is caused by the steric hindrance of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) that have been attached. Does not adsorb to the inorganic powder, so that the strength of the sheet obtained in the case of a green sheet can be increased without impairing the dispersibility of the inorganic powder. Thermal deformation can be reduced.
Therefore, since the high intensity | strength which the polyvinyl acetal resin for binders expresses without inhibiting the outstanding dispersibility of polyvinyl acetal resin (a1) and polyvinyl acetal resin (a2), the outstanding dispersibility of inorganic powder and Thus, a slurry composition having the effect of obtaining a film having high strength can be produced.

In the present invention, in the step of preparing the inorganic dispersion, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) act as a dispersant. As a result, it is not necessary to consider the adverse effects due to the addition of a dispersant as in the prior art. This is because the dispersant and the binder resin are the same type, so the compatibility is good and the dispersant and the binder can be mixed without separation.
In the present specification, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are also simply referred to as a polyvinyl acetal resin when it is not necessary to distinguish the polyvinyl acetal resin for binders described later.

In the step of preparing the inorganic dispersion, the water content of the inorganic dispersion is preferably less than 3% by weight. When the water content of the inorganic dispersion is 3% by weight or more, high dispersibility may not be maintained over a long period of time. Preferably it is less than 1% by weight.

In the present invention, next, a step of preparing a resin solution by adding and mixing the polyvinyl acetal resin for the binder and the organic solvent for the resin solution is performed.
In the present invention, the resin solution is prepared as described above, and the step of adding the resin solution to the inorganic dispersion in the subsequent step is performed to prevent the aggregation of the inorganic powder and to disperse the inorganic powder more finely. It becomes possible.
On the other hand, when the polyvinyl acetal resin for the binder is not dissolved in the organic solvent for the resin solution, that is, when the resin solution is not prepared, the polyvinyl acetal resin for the binder becomes bulky and takes in a plurality of inorganic powders. Since it becomes easy, aggregation of inorganic powder will be caused.

The minimum of the polymerization degree of the said polyvinyl acetal resin for binders is 800, and an upper limit is 4000. When the degree of polymerization is less than 800, the sheet strength is insufficient when used for a green sheet, and when the degree of polymerization exceeds 4000, the slurry composition becomes too viscous and coating becomes difficult. The preferable lower limit of the polymerization degree is 1200, and the preferable upper limit is 3500.

The minimum with the preferable amount of hydroxyl groups of the said polyvinyl acetal resin for binders is 43 mol%, and a preferable upper limit is 60 mol%. When the amount of the hydroxyl group is less than 43 mol%, when a green sheet is produced using a slurry containing the polyvinyl acetal resin, the sheet attack property may be insufficient. When the amount exceeds 60 mol%, Not only the solubility in the organic solvent for the resin solution is remarkably lowered but also aggregation of the inorganic powder particles may be caused. A more preferred lower limit of the hydroxyl group content is 46 mol%, and a more preferred upper limit is 56 mol%.

The preferable lower limit of the addition amount of the polyvinyl acetal resin for binder in the step of preparing the resin solution is 5 parts by weight with respect to 100 parts by weight of the inorganic composite for dispersing inorganic powder, and the preferable upper limit is 20 parts by weight. When the added amount of the polyvinyl acetal resin for the binder is less than 5 parts by weight, for example, the dispersibility of the inorganic powder is insufficient, or the strength, flexibility, adhesiveness and the like of the coating film after drying are insufficient. When the amount exceeds 20 parts by weight, the viscosity may become too high, or the coatability may deteriorate, and the handleability may deteriorate.
In particular, in a thin-layer ceramic green sheet for which strength is required, by containing a polyvinyl acetal resin for a binder having a high degree of polymerization with respect to the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) having a low degree of polymerization, A ceramic green sheet having sufficient dispersibility and sheet strength can be produced.

In the present invention, a step of adding a resin solution to the inorganic dispersion is then performed.
Thereby, a slurry composition is obtained.

In addition, in the manufacturing method of the slurry composition of this invention, in the range which does not impair the effect of this invention, other resins, such as polyvinyl acetal resins other than the said polyvinyl acetal resin, an acrylic resin, and ethyl cellulose, may be contained. . However, in such a case, the content of the polyvinyl acetal resin with respect to the total binder resin needs to be 50% by weight or more.

The organic solvent for inorganic dispersion and the organic solvent for resin solution are not particularly limited, and organic solvents generally used in slurry compositions can be used. For example, acetone, methyl ethyl ketone, dipropyl ketone, diisobutyl ketone Ketones such as methanol, ethanol, isopropanol, butanol, aromatic hydrocarbons such as toluene, xylene, methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butanoic acid Esters such as butyl, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, 2-ethylhexyl butyrate, terpineol, dihydroterpineol, terpineol Seteto, terpineol and its derivatives such as dihydro terpineol acetate, and the like. These organic solvents may be used independently and 2 or more types may be used together.

As the organic solvent for inorganic dispersion and the organic solvent for resin solution, it is particularly preferable to use a mixed solvent composed of ethanol and toluene. By using the mixed solvent, the dispersibility of the slurry composition can be greatly improved. This is because ethanol contributes to the prevention of aggregation of the polyvinyl acetal resin for the binder, while toluene contributes to the adhesion of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) to the inorganic powder surface. This is probably because the dispersibility of the slurry composition is greatly improved by the effect.

When the mixed solvent is used, the mixing ratio of ethanol and toluene is preferably 5: 5 to 2: 8. By setting it within the above range, the dispersibility of the slurry composition can be greatly improved.

The preferable lower limit of the amount of the inorganic dispersion organic solvent added in the step of preparing the inorganic dispersion is 20 parts by weight with respect to 100 parts by weight of the inorganic powder dispersing inorganic composite, and the preferable upper limit is 60 parts by weight. When the addition amount of the organic solvent for inorganic dispersion is less than 20 parts by weight, the viscosity of the inorganic dispersion becomes high, the movement of the inorganic powder is restricted, and sufficient dispersibility may not be obtained. If it exceeds, the inorganic powder concentration of the inorganic dispersion liquid becomes low and the number of collisions between the inorganic powders decreases, so that sufficient dispersibility may not be obtained.
Moreover, the preferable minimum of the addition amount of the said organic solvent for resin solutions in the process of producing the said resin solution is 70 weight part with respect to 100 weight part of inorganic composites for inorganic powder dispersion, and a preferable upper limit is 130 weight part. If the amount of the organic solvent for the resin solution is less than 70 parts by weight, the amount of the resin is not sufficient, so the strength of the green sheet may be insufficient. If the amount exceeds 130 parts by weight, the resin in the green sheet The amount of residue may increase in the baking process.

In the method for producing the slurry composition of the present invention, a plasticizer, a lubricant, an antistatic agent, and the like may be appropriately added as long as the effects of the present invention are not impaired.

By using the method for producing a slurry composition of the present invention, an extremely high dispersibility can be realized, and a slurry composition having a high strength can be produced. Such a slurry composition is also one aspect of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the inorganic composite for inorganic powder dispersion | distribution which can implement | achieve the outstanding dispersibility by a simple process can be provided. Moreover, the manufacturing method of this inorganic composite for inorganic powder dispersion | distribution, the manufacturing method of a slurry composition, and a slurry composition can be provided.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to these examples.

(Synthesis of polyvinyl acetal resin (a1) [(a1-1) to (a1-9)])
350 parts by weight of polyvinyl alcohol having a polymerization degree of 250 and a saponification degree of 99 mol% was added to 3000 parts by weight of pure water, and stirred at a temperature of 90 ° C. for about 2 hours for dissolution. The solution was cooled to 40 ° C., and 230 parts by weight of hydrochloric acid having a concentration of 35% by weight was added thereto. Then, the liquid temperature was lowered to 0 ° C., and 212 parts by weight of n-butyraldehyde was added to maintain the temperature. The reaction product was precipitated by the reaction. Then, the liquid temperature was kept at 20 ° C. for 3 hours to complete the reaction, and neutralized, washed with water and dried by a conventional method to obtain a white powder of polyvinyl acetal resin (a1-1). The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethylsulfoxaside), and the butyralization degree, the amount of hydroxyl groups and the amount of acetyl groups were measured using ¹³ C-NMR (nuclear magnetic resonance spectrum). The degree of conversion was 69 mol%, the amount of hydroxyl groups was 30 mol%, and the amount of acetyl groups was 1 mol%.
In addition, polyvinyl acetal resins (a1-2) to (a1-9) were synthesized in the same manner as the polyvinyl acetal resin (a1-1) except that the conditions shown in Table 1 were used.

(Synthesis of polyvinyl acetal resin (a2) [(a2-1) to (a2-10)])
350 parts by weight of polyvinyl alcohol having a polymerization degree of 320 and a saponification degree of 99 mol% was added to 3000 parts by weight of pure water, and stirred at a temperature of 90 ° C. for about 2 hours for dissolution. This solution was cooled to 40 ° C., and 230 parts by weight of hydrochloric acid having a concentration of 35% by weight was added thereto, and then the temperature of the solution was lowered to 1 ° C., and 157 parts by weight of n-butyraldehyde was added to maintain the temperature. The reaction product was precipitated by the reaction. Thereafter, the liquid temperature was kept at 20 ° C. for 3 hours to complete the reaction, and neutralized, washed with water and dried by a conventional method to obtain a white powder of polyvinyl acetal resin (a2-1). The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethylsulfoxaside), and the butyralization degree, the amount of hydroxyl groups and the amount of acetyl groups were measured using ¹³ C-NMR (nuclear magnetic resonance spectrum). The degree of conversion was 51 mol%, the amount of hydroxyl groups was 48 mol%, and the amount of acetyl groups was 1 mol%.
Further, polyvinyl acetal resins (a2-2) to (a2-10) were synthesized in the same manner as the polyvinyl acetal resin (a2-1) except that the conditions shown in Table 2 were used.
In addition, in polyvinyl acetal resin (a2-6), the anion modification | denaturation was performed by using carboxylic acid modification polyvinyl alcohol for a raw material.

(Synthesis of polyvinyl acetal resin (B) [(B1) to (B5)])
280 parts by weight of polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 99 mol% was added to 3000 parts by weight of pure water, and the mixture was stirred for dissolution for 2 hours at a temperature of 90 ° C. The solution is cooled to 10 ° C., 200 parts by weight of hydrochloric acid having a concentration of 35% by weight and 155 parts by weight of n-butyraldehyde are added thereto, the liquid temperature is lowered to 1 ° C., and this temperature is maintained to perform an acetalization reaction. And the reaction product was precipitated. Then, liquid temperature was hold | maintained at 40 degreeC for 3 hours, reaction was completed, and the white powder of polyvinyl acetal resin (B1) was obtained through neutralization, water washing, and drying by a conventional method. When the obtained polyvinyl acetal resin (B1) was dissolved in DMSO-d ₆ (dimethyl sulfoxide), the degree of butyralization, the amount of hydroxyl groups and the amount of acetyl groups were measured using ¹³ C-NMR (nuclear magnetic resonance spectrum). The degree of butyralization was 66 mol%, the amount of hydroxyl groups was 33 mol%, and the amount of acetyl groups was 1 mol%.
In addition, polyvinyl acetal resins (B2) to (B5) were synthesized in the same manner as the polyvinyl acetal resin (B1) except that the conditions shown in Table 3 were used.

Example 1
(Preparation of inorganic dispersion for preparing inorganic composite)
In addition to 0.5 parts by weight of the polyvinyl acetal resin (a1) shown in Table 4, a mixed solvent of 25 parts by weight of toluene and 25 parts by weight of ethanol, the mixture was dissolved by stirring. Next, 100 parts by weight of barium titanate powder (manufactured by Sakai Chemical Co., Ltd., BT01) was added to the obtained solution, 300 g of ceramic balls having a diameter of 0.5 mm were added, and rotation was performed using a bead mill (Ready Mill manufactured by Imex Corporation). After stirring at several 1500 rpm for 100 minutes, 0.5 part by weight of polyvinyl acetal resin (a2) was added and further stirred for 60 minutes to prepare an inorganic dispersion for preparing an inorganic composite.

(Preparation of inorganic composite)
The obtained inorganic dispersion for preparing an inorganic composite was poured into an aluminum tray and dried at 70 ° C. for 6 hours to obtain a block-shaped inorganic composite. Thereafter, the block-like inorganic composite was crushed with a coffee mill to obtain an inorganic composite. The obtained inorganic composite had an average particle size of 0.15 μm, a coating layer (inner layer) thickness of 15 nm, and a coating layer (outer layer) thickness of 14 nm. The total content of the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) was 0.7 parts by weight with respect to 100 parts by weight of the inorganic powder.

(Preparation of inorganic dispersion for slurry composition preparation)
A mixed solvent of 25 parts by weight of toluene and 25 parts by weight of ethanol and 300 parts by weight of a ceramic ball having a diameter of 0.5 mm were added to 100 parts by weight of the obtained inorganic composite, and the rotation speed was 1500 rpm using a bead mill (Ready Mill manufactured by IMEX Co., Ltd.). Were stirred for 100 minutes to prepare an inorganic dispersion for preparing a slurry composition.

(Preparation of resin solution for slurry composition preparation)
8 parts by weight of the obtained polyvinyl acetal resin (B1) and 2 parts by weight of DOP were added to a mixed solvent of 45 parts by weight of ethanol and 45 parts by weight of toluene, and dissolved by stirring to prepare a resin solution for preparing a slurry composition.

(Preparation of slurry composition)
The slurry composition preparation resin solution was added to the resulting slurry composition preparation inorganic dispersion, and the mixture was stirred for 120 minutes with a bead mill at a rotation speed of 1900 rpm to obtain a slurry composition.

(Examples 2 to 21)
An inorganic composite and a slurry composition were obtained in the same manner as in Example 1 except that the polyvinyl acetal resin (a1), the polyvinyl acetal resin (a2), the polyvinyl acetal resin (B) and the organic solvent shown in Table 4 were used. .

(Comparative Example 1)
The same as Example 1 except that the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) were not added to the inorganic dispersion for preparing the inorganic composite, and the polyvinyl acetal resin (B) and the organic solvent shown in Table 5 were used. Thus, a slurry composition was obtained.

(Comparative Examples 2 to 4)
Example 1 except that the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) were not added to the inorganic dispersion for preparing an inorganic composite and dissolved in the resin solution together with the polyvinyl acetal resin (B) shown in Table 5. Similarly, a slurry composition was obtained.

(Comparative Examples 5-12)
A slurry composition was obtained in the same manner as in Example 1 except that the polyvinyl acetal resin (a1), the polyvinyl acetal resin (a2), the polyvinyl acetal resin (B), and the organic solvent shown in Table 5 were used.

(Comparative Example 13)
A bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin, Epicoat 1001) is used instead of the polyvinyl acetal resin (a1), and the polyvinyl acetal resin (a2), the polyvinyl acetal resin (B), and the organic materials shown in Table 5 are used. A slurry composition was obtained in the same manner as in Example 1 except that the solvent was used.

(Comparative Example 14)
In place of the polyvinyl acetal resin (a2), an MDI-reactive urethane resin (manufactured by Mitsui Chemicals, Cosmonate M-200) is used, and the polyvinyl acetal resin (a1), the polyvinyl acetal resin (B) shown in Table 5, and A slurry composition was obtained in the same manner as in Example 1 except that an organic solvent was used.

(Comparative Examples 15 to 16)
The same as Example 1 except that the inorganic powder shown in Table 5 and the polyvinyl acetal resin as the dispersant and the organic solvent were used when preparing the inorganic dispersion for preparing the slurry composition without preparing the inorganic powder composite. Thus, a slurry composition was obtained.

(Comparative Example 17)
Without preparing the inorganic powder composite, the inorganic powder shown in Table 5 at the time of preparation of the inorganic dispersion for preparing the slurry composition, a polyamine compound grafted with hydrocarbon on the side chain of the dispersant as a dispersant ("Hypermer KD" manufactured by Croda) -2 ") was used in the same manner as in Example 1 to obtain a slurry composition.

(Evaluation)
The following evaluation was performed about the obtained slurry composition.

(1) Evaluation of green sheets (production of green sheets)
On the polyethylene terephthalate (PET) film subjected to the release treatment, the slurry composition was applied and dried so that the film thickness after drying was 20 μm, and a ceramic green sheet was produced.

(1-1) Surface Roughness About the ceramic green sheet obtained above, the surface roughness Ra was measured based on JIS B 0601 (1994), and the surface roughness of the ceramic slurry was evaluated.
Generally, the higher the dispersibility of the slurry composition, the smaller the surface roughness of the ceramic green sheet.

◎ Less than 0.025 μm ○ 0.025 μm or more, less than 0.035 μm Δ 0.035 μm or more, less than 0.045 μm × 0.045 μm or more

(1-2) Tensile modulus In accordance with JIS K 7113, measurement of the tensile modulus (MPa) is performed using AUTOGRAPH (“AGS-J”, manufactured by Shimadzu Corporation) under the condition of a tensile speed of 20 mm / min. went.

◎ 1600 MPa or more ○ 1400 MPa or more, less than 1600 MPa Δ 1200 MPa or more, less than 1400 MPa × less than 1200 MPa

(1-3) Evaluation of Thermal Deformation Rate The ceramic green sheet obtained above was cut into a 10 cm square to obtain a green sheet piece. A thermal deformation rate was calculated by applying a pressure of 100 kg / cm ² at 60 ° C. for 10 minutes to this green sheet piece and measuring the subsequent dimensions.

◎ Less than 3.0% ○ 3.0% or more, less than 5.0% △ 5.0% or more, less than 7.0% × 7.0% or more

(2) Dispersibility evaluation (Preparation of dispersibility evaluation solution)
0.1 part by weight of the obtained slurry composition is added to a mixed solvent of 5 parts by weight of ethanol and 5 parts by weight of toluene, and stirred for 10 minutes with an ultrasonic disperser (“US-303” manufactured by SNDI). As a result, a dispersion evaluation solution was prepared.

(Dispersibility evaluation)
The obtained dispersion evaluation solution was subjected to particle size distribution measurement using a laser diffraction particle size distribution analyzer (manufactured by Horiba, Ltd., LA-910), and the position of the maximum particle diameter peak and the average dispersion diameter were measured. The average dispersion diameter was evaluated according to the following criteria.

◎ Less than 0.4μm ○ 0.4μm or more, less than 0.5μm △ 0.5μm or more, less than 0.6μm x 0.6μm or more

(Examples 22 to 23)
Example except that aluminum nitride powder was used instead of barium titanate as inorganic powder, and polyvinyl acetal resin (a1), polyvinyl acetal resin (a2), polyvinyl acetal resin (B) and organic solvent shown in Table 8 were used. In the same manner as in No. 1, a slurry composition was obtained.

(Examples 24 to 25)
Instead of barium titanate as inorganic powder, Ni-Zn ferrite powder is used, except that the polyvinyl acetal resin (a1), polyvinyl acetal resin (a2), polyvinyl acetal resin (B) and organic solvent shown in Table 8 are used. Was similar to Example 1 to obtain a slurry composition.

(Comparative Example 18)
Instead of barium titanate as the inorganic powder, aluminum nitride powder was used, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) were not added, and the polyvinyl acetal resin (B) and the organic solvent shown in Table 8 were used. Except for this, a slurry composition was obtained in the same manner as in Example 1.

(Comparative Example 19)
Instead of barium titanate as the inorganic powder, Ni-Zn ferrite powder is used, the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) are not added, and the polyvinyl acetal resin (B) and the organic solvent shown in Table 8 are added. A slurry composition was obtained in the same manner as in Example 1 except that was used.

(Evaluation)
The following evaluation was performed about the obtained slurry composition.

(1) Evaluation of green sheets (production of green sheets)
On the polyethylene terephthalate (PET) film subjected to the release treatment, the slurry composition was applied and dried so that the film thickness after drying was 20 μm, and a ceramic green sheet was produced.

(1-1) Surface Roughness About the ceramic green sheet obtained above, the surface roughness Ra was measured based on JIS B 0601 (1994), and the surface roughness of the ceramic slurry was evaluated.
Generally, the higher the dispersibility of the slurry composition, the smaller the surface roughness of the ceramic green sheet.

◎ Less than 0.2μm ○ 0.2μm or more, less than 0.3μm △ 0.3μm or more, less than 0.4μm × 0.4μm or more

(1-2) Tensile modulus In accordance with JIS K 7113, measurement of the tensile modulus (MPa) is performed using AUTOGRAPH (“AGS-J”, manufactured by Shimadzu Corporation) under the condition of a tensile speed of 20 mm / min. went.

◎ 1500 MPa or more ○ 1200 MPa or more, less than 1500 MPa Δ 900 MPa or more, less than 1200 MPa × less than 900 MPa

(1-3) Evaluation of Thermal Deformation Rate The ceramic green sheet obtained above was cut into a 10 cm square to obtain a green sheet piece. A thermal deformation rate was calculated by applying a pressure of 100 kg / cm 2 at 60 ° C. for 10 minutes to the green sheet piece and measuring the subsequent dimensions.

◎ Less than 4.0% ○ 4.0% or more, less than 6.0% △ 6.0% or more, less than 8.0% × 8.0% or more

(2) Dispersibility evaluation (Preparation of dispersibility evaluation solution)
0.1 part by weight of the obtained slurry composition is added to a mixed solvent of 5 parts by weight of ethanol and 5 parts by weight of toluene, and stirred for 10 minutes with an ultrasonic disperser (“US-303” manufactured by SNDI). As a result, a dispersion evaluation solution was prepared.

(Dispersibility evaluation)
The obtained dispersion evaluation solution was subjected to particle size distribution measurement using a laser diffraction particle size distribution analyzer (Horiba, Ltd., LA-910), and the position of the maximum particle diameter peak and the average dispersion diameter were measured. . Further, the position of the maximum particle diameter peak after being allowed to stand at 23 ° C. for one week and the average dispersion diameter were also measured. The average dispersion diameter was evaluated according to the following criteria.

◎ Less than 2μm ○ 2μm or more, less than 3μm △ 3μm or more, less than 4μm × 4μm or more

ADVANTAGE OF THE INVENTION According to this invention, the inorganic composite for inorganic powder dispersion | distribution which can implement | achieve the outstanding dispersibility by a simple process can be provided. Moreover, the manufacturing method of this inorganic composite for inorganic powder dispersion | distribution, the manufacturing method of a slurry composition, and a slurry composition can be provided.

Claims (8)

An inorganic composite used for dispersion of inorganic powder,
Having a coating layer on the surface of the inorganic powder;
The coating layer has an inner layer made of a polyvinyl acetal resin (a1) having a hydroxyl group content of 20 to 40 mol% and an outer layer made of a polyvinyl acetal resin (a2) having a hydroxyl group content of 28 to 60 mol%, The inorganic composite for dispersing inorganic powder, wherein the polyvinyl acetal resin (a1) and the polyvinyl acetal resin (a2) have a relationship represented by the following formula (1).

In formula (1), X represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a1), and Y represents the amount of hydroxyl group (mol%) of the polyvinyl acetal resin (a2). The inorganic composite for dispersing an inorganic powder according to claim 1, wherein the polyvinyl acetal resin (a1) has a polymerization degree of 20 to 450. The inorganic composite for dispersing an inorganic powder according to claim 1 or 2, wherein the polyvinyl acetal resin (a2) has an anionic group. The inorganic composite for dispersing inorganic powder according to claim 1, 2 or 3, wherein the polyvinyl acetal resin (a2) has a degree of polymerization of 200 to 600. A method for producing an inorganic composite for dispersing an inorganic powder according to claim 1, 2, 3 or 4,
After adding and mixing the inorganic powder, the polyvinyl acetal resin (a1) and the organic solvent for coating, the step of preparing an inorganic dispersion by adding and mixing the polyvinyl acetal resin (a2), and the organic solvent for coating A method for producing an inorganic composite for dispersing an inorganic powder, comprising a step of drying. The inorganic composite for dispersing inorganic powder according to claim 5, wherein 0.1 to 20 parts by weight of polyvinyl acetal resin (a1) and polyvinyl acetal resin (a2) are added to 100 parts by weight of the inorganic powder. Manufacturing method. A step of adding an inorganic composite for dispersing an inorganic powder according to claim 1, 2, 3 or 4 to an organic solvent for inorganic dispersion and mixing to prepare an inorganic dispersion, a polyvinyl acetal resin for binder, and an organic solvent for resin solution. Adding, mixing to prepare a resin solution, and adding the resin solution to the inorganic dispersion;
The method for producing a slurry composition, wherein the polyvinyl acetal resin for a binder has a degree of polymerization of 800 to 4000. A slurry composition obtained by using the method for producing a slurry composition according to claim 7.