JP7180282B2 - Metal oxide nanoparticle dispersion for firing and method for producing sintered film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal oxide nanoparticle dispersion for sintering and a method for producing a sintered film.

Metal oxide nanoparticle dispersions obtained by dispersing metal oxide nanoparticles in a solvent are used in various industrial fields, such as electronic components such as capacitors, batteries, semiconductor substrates, various sensors and liquid crystal display elements. In addition to various functional layers provided by In recent years, in electronic component applications, there has been a demand for improvements in product characteristics such as miniaturization, high capacity, and high efficiency of components. And improvement of dispersion stability is demanded. In metal oxide nanoparticle dispersions for sintering applications such as dielectric layers of laminated ceramic capacitors and solid electrolytes of ceramic solid-state batteries, easy decomposition of organic components in the sintering process is also required.

Conventionally, in order to obtain a dispersion of metal oxide nanoparticles, for example, a commercially available phosphate-based dispersant has been used as a dispersant for inorganic particles.
Further, Patent Documents 1 and 2 disclose a method of modifying the surface of metal oxide nanoparticles with a surface treatment agent such as a silane coupling agent.
Furthermore, the present applicant has disclosed in Patent Document 3 a graft copolymer having a structural unit having a nitrogen site and a structural unit having a polymer chain, wherein at least part of the nitrogen site forms a salt with a specific compound. is used as a dispersant, and a metal particle dispersion is disclosed in which specific metal particles are dispersed in an organic solvent.
Patent Document 4 discloses a non-aqueous dispersion composition in which an inorganic powder is dispersed in a non-aqueous solvent using a polyether ester compound composed of a polyether having a specific structure and a tricarboxylic anhydride as a dispersant. It is

On the other hand, polymers having hydrolyzable silyl groups at their ends are used as coating materials for modifying material surfaces (Patent Documents 5 to 7). However, polymers having hydrolyzable silyl groups at their ends are used for the purpose of surface modification such as hydrophilization of substrates, and the fact that they are used as dispersants for metal oxide nanoparticle dispersions for sintering is unknown. Not mentioned or suggested.

JP 2010-254889 A JP 2016-128374 A JP 2014-88550 A JP 2016-147261 A JP-A-7-3171 JP-A-2002-293824 JP 2011-236403 A

In the metal oxide nanoparticle dispersion for sintering, as described above, the metal oxide nanoparticles are required to be finely divided and to improve the dispersion stability, as well as the easy decomposability of the organic component in the sintering process.
However, when metal oxide nanoparticles are dispersed in a solvent using a phosphate-based dispersant, the dispersion stability is insufficient, as shown in Comparative Examples 4 and 5 below. There is a problem that the particles tend to settle. In addition, the phosphate ester-based dispersant and the dispersant of Patent Document 4 also have a problem that, when used for firing, the organic component derived from the dispersant cannot be sufficiently removed in the firing process.
In the method using a low-molecular-weight compound such as a silane coupling agent as described in Patent Documents 1 and 2, although the dispersion stability is good for particles on the order of several nanometers, particles on the order of several tens of nanometers , the dispersion stability is insufficient, and the metal oxide nanoparticles tend to sediment. As shown in Comparative Examples 2 and 3 described later, when attempting to disperse metal oxide nanoparticles of the order of several tens of nm in a solvent using a silane coupling agent, the solvent phase and precipitated metal oxide nanoparticles Phase separation occurs between the nanoparticle phase and the nanoparticle phase.
The dispersant of Patent Document 3 has a reduced amount of residual organic components after sintering, but since the nitrogen sites become adsorption groups, it is difficult to remove a small amount of residual nitrogen components after sintering. be.
In addition, in metal oxide nanoparticle dispersions for sintering, further improvement in dispersibility and dispersion stability of metal oxide nanoparticles is required.

The present invention has been made under such circumstances. An object of the present invention is to provide a method for producing a sintered film using a composition containing an oxide nanoparticle dispersion and the metal oxide nanoparticle dispersion for firing.

The metal oxide nanoparticle dispersion for firing according to the present invention contains metal oxide nanoparticles, a dispersant, and an organic solvent,
The dispersant is a polymer compound having a hydrolyzable silyl group represented by the following general formula (II) at one end of the main chain of a polymer chain having a structural unit represented by the following general formula (I). It is characterized by

（一般式（Ｉ）中、Ｒ^１は水素原子又はメチル基、Ｌ^１は直接結合又は２価の連結基、Ｒ^２は炭化水素基を表す。）

(In general formula (I), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents a direct bond or a divalent linking group, and R ² represents a hydrocarbon group.)

（一般式（ＩＩ）中、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子又は炭化水素基、Ｌ^２は２価の連結基を表し、ｍは１以上３以下の整数を表す。）

(In general formula (II), R ³ and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group, L ² represents a divalent linking group, and m represents an integer of 1 or more and 3 or less.)

In the metal oxide nanoparticle dispersion for firing of the present invention, in the structural unit represented by the general formula (I), L ¹ in the general formula (I) is a —COO— group and R ² is —CH ₂ represents a monovalent group represented by R ²¹ , and R ²¹ is preferably a hydrogen atom or an alkyl group from the standpoint of decomposability of organic components by calcination.
In the metal oxide nanoparticle dispersion for calcination of the present invention, it is more preferable that the R ²¹ is a branched alkyl group from the viewpoint of the decomposition of the organic component by the calcination treatment.

In the metal oxide nanoparticle dispersion for sintering of the present invention, the average particle size of the metal oxide nanoparticles is 10 nm or more and 200 nm or less. It is preferable from the point of suppressing the sedimentation of.

In the metal oxide nanoparticle dispersion for firing of the present invention, the metal oxide nanoparticles have, on at least their surfaces, zirconium oxide, aluminum oxide, titanium oxide, indium oxide, indium tin oxide, zinc oxide, cerium oxide, The inclusion of at least one metal oxide selected from the group consisting of barium titanate, barium zirconate, barium zirconate titanate, and strontium titanate is advantageous in dispersibility, dispersion stability, and metal oxide nanoparticles. It is preferable from the point of suppressing the sedimentation of.

Further, the present invention provides a step of applying a composition containing the metal oxide nanoparticle dispersion for firing according to the present invention on a substrate to form a coating film, and a step of firing the coating film. A method for producing a sintered membrane is provided.

According to the present invention, there is provided a dispersion of metal oxide nanoparticles for firing, which is excellent in dispersibility and dispersion stability, suppresses sedimentation of metal oxide nanoparticles, and improves decomposability of organic components by firing treatment; A method for producing a sintered film using a composition containing a metal oxide nanoparticle dispersion for sintering can be provided.

Hereinafter, the metal oxide nanoparticle dispersion for firing and the method for producing a sintered film according to the present invention will be described.
In the present invention, light includes electromagnetic waves with wavelengths in the visible and non-visible regions, and radiation, and radiation includes, for example, microwaves and electron beams. Specifically, it refers to electromagnetic waves with a wavelength of 5 μm or less and electron beams. Moreover, in the present invention, (meth)acryl represents each of acrylic and methacrylic, and (meth)acrylate represents each of acrylate and methacrylate.

[Metal oxide nanoparticle dispersion for firing]
The metal oxide nanoparticle dispersion for firing according to the present invention contains metal oxide nanoparticles, a dispersant, and an organic solvent,
The dispersant is a polymer compound having a hydrolyzable silyl group represented by the following general formula (II) at one end of the main chain of a polymer chain having a structural unit represented by the following general formula (I). It is characterized by

（一般式（Ｉ）中、Ｒ^１は水素原子又はメチル基、Ｌ^１は直接結合又は２価の連結基、Ｒ^２は炭化水素基を表す。）

(In general formula (I), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents a direct bond or a divalent linking group, and R ² represents a hydrocarbon group.)

（一般式（ＩＩ）中、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子又は炭化水素基、Ｌ^２は２価の連結基を表し、ｍは１以上３以下の整数を表す。）

(In general formula (II), R ³ and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group, L ² represents a divalent linking group, and m represents an integer of 1 or more and 3 or less.)

Conventionally, a metal oxide nanoparticle dispersion has a problem that the particles tend to settle during storage because the specific gravity of the metal oxide nanoparticles is larger than that of each component in the dispersion. Polymeric dispersants can suppress sedimentation of particles due to steric repulsion of polymer chains. be. On the other hand, dispersions of metal oxide nanoparticles, which are used in applications that require thin film coating and firing processes, such as the dielectric layers of multilayer ceramic capacitors, have excellent dispersibility and dispersion stability, and organic Both of the easily degradable components are required.
The metal oxide nanoparticle dispersion for sintering according to the present invention is excellent in dispersibility and dispersion stability by using the metal oxide nanoparticles in combination with the above-mentioned specific dispersant, and sedimentation of the metal oxide nanoparticles is suppressed, and furthermore, the decomposability of the organic component by the calcination treatment is improved.
Although there are some unexplained aspects of the action of the specific combination to exert the specific effects as described above, it is presumed as follows.
In the metal oxide nanoparticle dispersion for firing of the present invention, the dispersant is represented by the general formula (II) at one end of the main chain of the polymer chain having the structural unit represented by the general formula (I). a polymer compound having a hydrolyzable silyl group, wherein the specific polymer chain has excellent solubility in an organic solvent, and the specific hydrolyzable silyl group is a hydroxyl group on the surface of the metal oxide nanoparticles. They can be chemically bonded by dehydration condensation. Therefore, when the metal oxide nanoparticles are dispersed in an organic solvent using the specific polymer compound as a dispersant, one end of the specific polymer compound binds to the surface of the metal oxide nanoparticles, Since the polymer chains are on the outside and sterically repel each other, it is believed that the specific polymer compound surrounds the metal oxide nanoparticles and exists stably in the solvent, dispersing the metal oxide nanoparticles. Here, the adsorption between the metal oxide nanoparticles and the dispersing agent is not physical adsorption but chemical adsorption, thereby further improving the dispersion stability of the metal oxide nanoparticles. As a result, the metal oxide nanoparticle dispersion for sintering of the present invention is less prone to agglomeration of the metal oxide nanoparticles, has excellent dispersibility and dispersion stability, and suppresses sedimentation of the metal oxide nanoparticles. presumed to be able to
Further, when producing a sintered film by baking a coating film of a composition containing a metal oxide nanoparticle dispersion for firing according to the present invention, the metal oxide nanoparticles are formed between the specific dispersant and the Since the chemical bonds formed are easily hydrolyzed by heating, the specific dispersant is easily released from the surface of the metal oxide nanoparticles by the baking treatment. Furthermore, the specific dispersant has a polymer chain having the specific structural unit, and is easily depolymerized by heating, and therefore easily decomposed by baking treatment. Therefore, the sintered film obtained by the production method of the present invention has a reduced amount of residual organic components. When the residual amount of the organic component contained in the sintered film is small, desired functions such as electrical conductivity are likely to be exhibited.
Furthermore, the metal oxide nanoparticle dispersion for firing according to the present invention is excellent in the dispersibility and dispersion stability of the metal oxide nanoparticles as described above. It is also possible to keep the content ratio of the dispersant to a low level. Therefore, the metal oxide nanoparticle dispersion for sintering according to the present invention can have a low viscosity by reducing the content of the dispersant, and further reduces the residual amount of the organic component in the sintered film. It is possible.
In the present invention, a specific guideline for low viscosity is that the viscosity of the metal oxide nanoparticle dispersion for sintering is 10 mPa·s or less, and more preferably 3 mPa·s or less. Such a low-viscosity sintering metal oxide nanoparticle dispersion can also be suitably used as an inkjet composition.
Moreover, since the metal oxide nanoparticle dispersion for firing according to the present invention is excellent in the dispersibility and dispersion stability of the metal oxide nanoparticles, it can contain the metal oxide nanoparticles at a high concentration. By using a dispersion containing metal oxide nanoparticles at a high concentration, it is possible to form a coating film with a high concentration of metal oxide nanoparticles, so that the coating film can be made thinner. The metal oxide nanoparticle dispersion for firing of the present invention, which contains metal oxide nanoparticles at a high concentration, can be suitably used, for example, for forming a dielectric ceramic sheet (green sheet).

The metal oxide nanoparticle dispersion for firing of the present invention contains at least metal oxide nanoparticles, a dispersant, and an organic solvent. It may contain other components.
Hereinafter, each component of the metal oxide nanoparticle dispersion for sintering of the present invention will be described in detail in order.

<Metal oxide nanoparticles>
The metal oxide nanoparticles used in the present invention may be particles containing a metal oxide at least on their surfaces and having an average particle size of several nanometers to several hundreds of nanometers in dispersion. It may contain a metal oxide, or the surface of metal particles may be oxidized to form a metal oxide.
The metal oxide is not particularly limited as long as it is used for firing, and can be appropriately selected depending on the application. Examples include zirconium oxide (ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), Titanium oxide ( _TiO2 ), indium oxide ( _In2O3 ), indium tin oxide ( _ITO ), zinc oxide (ZnO), cerium oxide ( _CeO2 ), barium titanate ( _BaTiO3 ), barium zirconate ( _BaZrO3) ), barium zirconate titanate (Ba(ZrTi) _O3 ), strontium titanate ( _SrTiO3 ), lead zirconate titanate (Pb(ZrTi) _O3 ), iron oxide ( _Fe2O4 ), magnesium oxide ₍ MgO), copper oxide (CuO), and La _0.51 Li _0.34 TiO _2.94 (perovskite type) and Li ₇ La ₃ Zr ₂ O ₁₂ (garnet type) that can be used for ceramic solid-state batteries. . Among them, the metal oxides include zirconium oxide, aluminum oxide, and titanium oxide because the dispersibility and dispersion stability are easily improved by combining with a dispersant described later, and sedimentation of the metal oxide nanoparticles is easily suppressed. , indium oxide, indium tin oxide, zinc oxide, cerium oxide, barium titanate, barium zirconate, barium zirconate titanate and strontium titanate. At least one selected from the group consisting of titanium, indium tin oxide, zinc oxide, cerium oxide and barium titanate is more preferred. At least one selected from barium titanate and barium zirconate titanate is also preferable as a metal oxide suitably used as a ceramic dielectric for ceramic capacitor applications.

In the metal oxide nanoparticles, the area occupied by the metal oxide in the entire surface of the metal oxide nanoparticles is preferably 95% or more, more preferably 98% or more, and 99%. The above is even more preferable.
Further, when the metal oxide nanoparticles as a whole contain the metal oxide uniformly, the content of the metal oxide contained in the metal oxide nanoparticles is preferably 95% by mass or more, preferably 98%. It is more preferably 99% or more, and even more preferably 99% or more.

The average particle size of the metal oxide nanoparticles in the dispersion is not particularly limited, and may be appropriately set according to the application. From the viewpoint of high effect, it is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more, while it is preferably 200 nm or less, and more preferably 150 nm or less. It is preferably 100 nm or less, and more preferably 100 nm or less.
The average particle size of the metal oxide nanoparticles in the dispersion is the dispersed particle size that can be measured with a dynamic light scattering (DLS) particle size distribution analyzer.

In addition, the average primary particle size of the metal oxide nanoparticles before being dispersed in an organic solvent may be appropriately set according to the application, and is not particularly limited. From the viewpoint of a high effect of improving dispersion stability, it is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more, while it is preferably 200 nm or less, and 100 nm. It is more preferably 50 nm or less, and even more preferably 50 nm or less.
The average primary particle size of the metal oxide nanoparticles before being dispersed in the organic solvent can be determined by a method of directly measuring the size of the primary particles from an electron micrograph. Specifically, the minor axis diameter and the major axis diameter of each primary particle are measured, and the average thereof is taken as the particle diameter of the particle. Next, for 100 or more particles, the volume (mass) of each particle is obtained by approximating the obtained particle size to a rectangular parallelepiped, and the volume-average particle size is obtained. The same result can be obtained by using a transmission type (TEM), scanning type (SEM) or scanning transmission type (STEM) electron microscope.

In the metal oxide nanoparticle dispersion for firing of the present invention, the content of the metal oxide nanoparticles may be appropriately selected depending on the application. and may be 2% by mass or more, or may be 3% by mass or more. On the other hand, from the viewpoint of dispersibility, dispersion stability, and suppression of sedimentation of metal oxide nanoparticles, the content of metal oxide nanoparticles should be 50% by mass or less with respect to the total amount of the dispersion. is preferable, 40% by mass or less is more preferable, and 30% by mass or less is even more preferable. In the present invention, by using a dispersant to be described later, even when the content of the metal oxide nanoparticles is increased compared to the prior art, the metal oxide nanoparticles are excellent in dispersibility and dispersion stability, It is possible to make sediments less likely to occur.
In the metal oxide nanoparticle dispersion for firing of the present invention, by using a dispersing agent described later, the metal oxide nanoparticles are excellent in dispersibility and dispersion stability, and sedimentation of the metal oxide nanoparticles is suppressed. Therefore, the metal oxide nanoparticles can be contained at a high concentration, for example, the content of the metal oxide nanoparticles can be 5% by mass or more relative to the total amount of the dispersion, and further, 10 mass % or more, and can be 20 mass % or more.
The metal oxide nanoparticles may be used singly or in combination of two or more.

<Dispersant>
The dispersant used in the metal oxide nanoparticle dispersion for firing of the present invention is represented by the following general formula (II) at one end of the main chain of the polymer chain having the structural unit represented by the following general formula (I). It is a polymer compound having a hydrolyzable silyl group.

（一般式（Ｉ）中、Ｒ^１は水素原子又はメチル基、Ｌ^１は直接結合又は２価の連結基、Ｒ^２は炭化水素基を表す。）

(In general formula (I), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents a direct bond or a divalent linking group, and R ² represents a hydrocarbon group.)

（一般式（ＩＩ）中、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子又は炭化水素基、Ｌ^２は２価の連結基を表し、ｍは１以上３以下の整数を表す。）

(In general formula (II), R ³ and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group, L ² represents a divalent linking group, and m represents an integer of 1 or more and 3 or less.)

Since the polymer chain of the polymer compound has the structural unit represented by the general formula (I), it has good solvent affinity and excellent decomposability by sintering. The polymer chain is not particularly limited as long as it has a structural unit represented by the general formula (I), and may be a homopolymer or a copolymer.

In the general formula (I), ^L1 is a direct bond or a divalent linking group. The fact that L ¹ is directly bonded means that R ² is directly bonded to a carbon atom without a linking group. The divalent linking group for L ¹ is not particularly limited as long as it can link the ethylenically unsaturated double bond and the hydrocarbon group represented by R ² . CONH- group, -NHCOO- group, ether group (-O- group), thioether group (-S- group), and at least one selected from these groups, and at least one selected from alkylene groups and arylene groups and the like. L ¹ is, among others, a direct bond or a divalent linkage represented by -CONH- group, -COO- group, -R-CONH- or -R-COO- from the viewpoint of dispersibility and dispersion stability is preferably a group (here, R represents an alkylene group), more preferably a divalent linking group represented by -COO- group or -R-COO-, and -COO- group is even more preferable.

In the general formula (I), ^R2 represents a hydrocarbon group. Examples of hydrocarbon groups for R ² include alkyl groups, alkenyl groups, aryl groups and aralkyl groups.
The alkyl group may be linear, branched or cyclic, and examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, bornyl group, isobornyl group, dicyclopentanyl group, adamantyl group, lower alkyl group-substituted adamantyl group and the like. The number of carbon atoms in the alkyl group is preferably 1 or more and 18 or less, more preferably 2 or more and 10 or less, and even more preferably 3 or more and 8 or less.
The alkenyl group may be linear, branched or cyclic, and examples thereof include vinyl, allyl and propenyl groups. The number of carbon atoms in the alkenyl group is preferably 2 or more and 18 or less, more preferably 3 or more and 10 or less.
Examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, and a xylyl group. The number of carbon atoms in the aryl group is preferably 6 or more and 24 or less, more preferably 6 or more and 12 or less.
Examples of the aralkyl group include benzyl group, phenethyl group, naphthylmethyl group, biphenylmethyl group and the like. The number of carbon atoms in the aralkyl group is preferably 7 or more and 20 or less, more preferably 7 or more and 14 or less.
Among them, the hydrocarbon group for R ² is preferably an alkyl group, more preferably a straight or branched alkyl group, and a straight chain having 1 to 18 carbon atoms, from the viewpoint of excellent solvent affinity and excellent decomposability by baking treatment. Chain or branched alkyl groups are even more preferred.

The structural unit represented by the general formula (I) has excellent solvent affinity, excellent decomposability by baking treatment, and can reduce the amount of residual organic components after baking treatment. L ¹ in (I) is a —COO— group, R ² is a monovalent group —CH ₂ —R ²¹ , and R ²¹ is preferably a hydrogen atom or an alkyl group. In this case, since the reaction between adjacent structural units can be suppressed in the firing step, residual organic components such as methacrylic anhydride generated by condensation between adjacent structural units can be reduced.
Although the alkyl group is not particularly limited, it is preferably a linear or branched alkyl group. The number of carbon atoms in the alkyl group is preferably 1 or more and 17 or less, more preferably 2 or more and 10 or less, and even more preferably 3 or more and 8 or less.
The R ²¹ reduces the residual amount of the organic component after the baking treatment, further reduces the decomposition temperature of the dispersant, and reduces the baking temperature when baking the coating film of the dispersion of the present invention. is preferably a branched alkyl group. Moreover, the number of carbon atoms in the branched alkyl group is preferably 3 or more and 10 or less.

The monomer from which the ^structural unit represented by general formula (I) is derived is not particularly _limited ^. Examples of monovalent groups represented by R ²¹ include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) Acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate and the like. Among these, those in which R ²¹ is a branched alkyl group are isobutyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate and isodecyl (meth)acrylate. .

In the polymer compound, the polymer chain may have a constitutional unit represented by the general formula (I). It may further have another structural unit different from the structural unit. When the polymer chain further has other structural units different from the structural units represented by the general formula (I), the general formula (I) out of 100% by mass of all structural units contained in the polymer chain From the viewpoint of solvent affinity of the polymer chain, the proportion of the structural unit represented by is preferably 60% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. More preferably, it is particularly preferably 90% by mass or more.
In addition, in the present invention, the content ratio of each structural unit in the polymer chain can be calculated from the charged amount when synthesizing the polymer chain.

In the polymer compound, the other structural unit different from the structural unit represented by the general formula (I), which the polymer chain may have, is represented by the following general formula (III), for example. can be mentioned.

（一般式（ＩＩＩ）中、Ｒ^５は水素原子又はメチル基、Ｌ^３は直接結合又は２価の連結基、Ｒ^６は、水素原子、又は、水酸基、アミノ基、酸性基及びエポキシ基からなる群から選ばれる少なくとも１種の官能基若しくは当該官能基を有する炭化水素基を表す。）

(In the general formula (III), R ⁵ is a hydrogen atom or a methyl group, L ³ is a direct bond or a divalent linking group, and R ⁶ is a hydrogen atom or a hydroxyl group, an amino group, an acidic group and an epoxy group. represents at least one functional group selected from the group or a hydrocarbon group having the functional group.)

In the general formula (III), ^L3 is a direct bond or a divalent linking group. The divalent linking group for ^L3 is not particularly limited as long as it can link the ethylenically unsaturated double bond and the monovalent group represented by ^R6 . -CONH- group, -NHCOO- group, ether group (-O- group), thioether group (-S- group), and at least one selected from these, an alkylene group optionally having a functional group and A combination with at least one selected from arylene groups is included. Examples of the functional group that the divalent linking group in L ³ may have include the same functional groups as those in R ⁶ to be described later.

In the general formula (III), R ⁶ represents a hydrogen atom, at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an acidic group and an epoxy group, or a hydrocarbon group having such a functional group. . Examples of the hydrocarbon group include those similar to the hydrocarbon group for R ² in the general formula (I). The amino group may be any of primary amino group, secondary amino group, tertiary amino group and quaternary ammonium group. Examples of the acidic group include a carboxy group, a sulfo group, and a phosphoric acid group.

The monomer from which the structural unit represented by the general formula (III) is derived is not particularly limited. For example, (meth)acrylic acid; a monomer having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate body; monomers having an amino group such as N,N-dimethylamino (meth)acrylate; acidity such as 2-((meth)acryloyloxy)ethanesulfonic acid and 2-((meth)acryloyloxy)ethyl phosphate monomers having a group; monomers having an epoxy group such as epoxycyclohexenyl (meth)acrylate;

The polymer compound has a hydrolyzable silyl group represented by the general formula (II) at one end of the main chain of the polymer chain In the general formula (II), R ³ and R ⁴ are each independently , represents a hydrogen atom or a hydrocarbon group. The hydrocarbon group for R ³ and R ⁴ may be linear, branched, or cyclic, and the hydrolyzable silyl group represented by the general formula (II) and the metal oxide nanoparticles The number of carbon atoms is preferably 1 or more and 8 or less, more preferably 1 or more and 6 or less, because dehydration condensation with the hydroxyl groups on the surface of is likely to occur.
Specific examples of hydrocarbon groups for R ³ and R ⁴ include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, n- butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group and the like.
Among them, the hydrolyzable silyl group represented by the general formula (II) and the hydroxyl group on the surface of the metal oxide nanoparticles are likely to undergo dehydration condensation, so R ³ and R ⁴ are each independently a hydrogen atom or An alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

In the general formula (II), ^L2 is a divalent linking group. The divalent linking group for L ² is not particularly limited as long as it can link the carbon atom at one end of the main chain of the polymer chain with the silicon atom in the general formula (II). At least one selected from an ether group (-O- group), a thioether group (-S- group), a -COO- group, and these groups from the viewpoint of reducing the amount of residual organic components after treatment; A combination with a divalent hydrocarbon group is preferred, and the number of carbon atoms in the divalent hydrocarbon group is preferably 1 or more and 10 or less. From the viewpoint that the polymer compound can be easily synthesized by a chain transfer method, L ² is further a divalent group represented by —OR ^L1 —S—, wherein R ^L1 is a divalent carbonized group. A hydrogen group is preferred. The divalent hydrocarbon group for R ^L1 is preferably an alkylene group, an arylene group, or a combination thereof, more preferably a linear or branched alkylene group. From the viewpoint of reducing the amount of organic components remaining after the firing treatment, the divalent hydrocarbon group in R ^L1 preferably has 1 or more and 10 or less carbon atoms, more preferably 1 or more and 6 or less. preferable.

In the general formula (II), m is an integer of 1 or more and 3 or less, and is preferably 2 or 3 in terms of dispersibility, dispersion stability, and suppression of sedimentation of metal oxide nanoparticles. , 3 are more preferred.

For example, when the polymer compound is produced by a chain transfer method, the hydrolyzable silyl group represented by the general formula (II) is introduced to one end of the main chain of the polymer chain using a chain transfer agent. can be done.
Examples of chain transfer agents that induce hydrolyzable silyl groups represented by general formula (II) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyldimethylmethoxysilane and the like.

The weight-average molecular weight Mw of the polymer compound improves the dispersibility and dispersion stability of the metal oxide nanoparticles, suppresses sedimentation of the metal oxide nanoparticles, and reduces the residual amount of the organic component after the baking treatment. It is preferably 1,000 or more and 10,000 or less from the viewpoint of dispersibility, more preferably 1,500 or more and 8,000 or less, and even more preferably 2,000 or more and 4,000 or less from the viewpoint of improving dispersibility.

Further, the molecular weight dispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polymer compound, is the dispersibility and dispersion stability of the metal oxide nanoparticles. It is preferably 1.0 or more and 3.0 or less, more preferably 1.1 or more and 2.5 or less, and even more preferably 1.2 or more and 2.0 or less.

The weight average molecular weight Mw and number average molecular weight Mn are values measured by GPC (gel permeation chromatography). The measurement was carried out using Tosoh's HLC-8120GPC, the elution solvent was N-methylpyrrolidone to which 0.01 mol/liter of lithium bromide was added, and the polystyrene standard for the calibration curve was Mw 377400, 210500, 96000, 50400, 20650. , 10850, 5460, 2930, 1300, 580 (Easi PS-2 series manufactured by Polymer Laboratories) and Mw 1090000 (manufactured by Tosoh Corporation), and the measurement column is TSK-GEL ALPHA-M × 2 (manufactured by Tosoh Corporation). done.

In the metal oxide nanoparticle dispersion for sintering of the present invention, the content of the dispersing agent is determined from the viewpoint of the dispersibility and dispersion stability of the metal oxide nanoparticles, and from the viewpoint of suppressing sedimentation of the metal oxide nanoparticles. , With respect to 100 parts by mass of the metal oxide nanoparticles, it is usually in the range of 1 part by mass or more and 100 parts by mass or less, preferably 5 parts by mass or more and 70 parts by mass or less, and 10 parts by mass or more and 50 parts by mass The following are more preferable.
In addition, the said dispersing agent can be used individually by 1 type or in mixture of 2 or more types.

(Manufacturing method of dispersant)
The method for producing the dispersant used in the present invention is not particularly limited, and for example, it can be produced by a living polymerization method such as living radical polymerization, living anionic polymerization, or living cationic polymerization, or a chain transfer method. Among them, the chain transfer method is a simple synthesis method, is preferable from the viewpoint of industrialization, and is preferable from the point that terminal reaction control and molecular weight control are easy.

As a method for producing the dispersant by a chain transfer method, for example, a monomer that induces each structural unit of the polymer chain, that is, a monomer represented by the following general formula (I'), and the present invention Other monomers different from the monomer represented by the following general formula (I') contained within a range that does not impair the effect of the chain transfer agent represented by the following general formula (II') and a method of radical polymerization under the conditions.

（一般式（Ｉ’）中のＲ^１、Ｌ^１及びＲ^２は、前記一般式（Ｉ）と同様である。）

(R ¹ , L ¹ and R ² in general formula (I′) are the same as in general formula (I).)

（一般式（ＩＩ’）中のＲ^３、Ｒ^４、及びｍは前記一般式（ＩＩ）と同様であり、Ｒ^Ｌ１は２価の炭化水素基を表す。）

(R ³ , R ⁴ and m in general formula (II′) are the same as in general formula (II) above, and R ^L1 represents a divalent hydrocarbon group.)

The divalent hydrocarbon group for R ^{1 L1} in general formula (II′) is the same as the divalent hydrocarbon group for R ^{1 L1} described in general formula (II).

Examples of the monomer represented by the general formula (I′) include those similar to the monomers that induce the structural unit represented by the general formula (I) described above. The species can be used alone or in combination of two or more.
Examples of the chain transfer agent represented by the general formula (II′) include those similar to the chain transfer agent that induces the hydrolyzable silyl group represented by the general formula (II) described above. It can be used singly or in combination of two or more.
Examples of other monomers different from the monomer represented by the general formula (I') include monomers represented by the following general formula (III').

（一般式（ＩＩＩ’）中のＲ^５、Ｌ^３及びＲ^６は、前記一般式（ＩＩＩ）と同様である。）

(R ⁵ , L ³ and R ⁶ in general formula (III′) are the same as in general formula (III).)

As the monomer represented by the general formula (III′), for example, the same monomers as those that induce the structural unit represented by the general formula (III) can be mentioned. The species can be used alone or in combination of two or more.

The addition amount of the chain transfer agent represented by the general formula (II′) when producing the dispersant is not particularly limited, but is 0.1 parts by mass or more with respect to the total 100 parts by mass of the monomers. The content of 10 parts by mass or less is preferable from the viewpoint of facilitating control of terminal reaction and molecular weight.

A polymerization initiator is preferably used when radically polymerizing the monomers from which each structural unit of the polymer chain is derived in the presence of a chain transfer agent represented by the following general formula (II′). As the polymerization initiator, a known one can be appropriately selected and used, and is not particularly limited. Examples include α,α'-azobisisobutyronitrile, methyl azoisobutyrate, azobisdimethylvaleronitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, benzophenone derivatives, phosphine oxide derivatives, benzoketone derivatives, phenylthioether derivatives, azide derivatives, diazo derivatives, disulfide derivatives and the like.
These polymerization initiators can be used singly or in combination of two or more.

The amount of the polymerization initiator to be added is such that it is easy to introduce the hydrolyzable silyl group represented by the general formula (II) only at one end of the main chain of the polymer chain, so that the general formula ( It is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and 30 parts by mass or less with respect to 100 parts by mass of the chain transfer agent that induces the hydrolyzable silyl group represented by II). is even more preferred. On the other hand, from the viewpoint of reactivity, the amount of the polymerization initiator added is preferably 0.01 parts by mass or more, and is 0.1 parts by mass or more with respect to the total 100 parts by mass of the monomers. is more preferable, and 0.5 parts by mass or more is even more preferable.

As a method for the radical polymerization, a known polymerization method can be used, and there is no particular limitation. For example, a solution polymerization method can be used. The dispersant solution obtained by the solution polymerization method can be used as it is for preparing the metal oxide nanoparticle dispersion for firing of the present invention.
When a solution polymerization method is used as the radical polymerization method, for example, the monomer represented by the general formula (I′), and the other monomers contained within a range that does not impair the effects of the present invention, The polymer compound can be obtained by a method in which the chain transfer agent represented by the general formula (II′) and the polymerization initiator are added to a solvent and stirred to react. This method is preferable because the amount of initiation radicals generated and the amount of the chain transfer agent with respect to the monomer are constant, so that the molecular weight can be easily stabilized. In this method, the monomer, the chain transfer agent and the polymerization initiator may be added separately to the solvent, or a premixed mixture thereof may be added to the solvent.

As the solvent, a solvent capable of dissolving the monomer and the chain transfer agent can be appropriately selected and used, and is not particularly limited. Examples thereof include the same organic solvents as described later. .
The amount of the solvent to be added is not particularly limited, but it is preferable to adjust the solid content concentration in the solution to 5% by mass or more and 80% by mass or less from the viewpoint of reactivity and handling. .
In the present invention, the solid content means all components other than the solvent, including liquid monomers and the like.

The atmosphere during the radical polymerization is preferably an inert gas atmosphere. Examples of the inert gas include, but are not limited to, nitrogen gas, argon gas, and the like.

In addition, the reaction temperature and reaction time during the radical polymerization are appropriately adjusted according to the type and content ratio of the monomer and the chain transfer agent, and are not particularly limited, but the reaction temperature is, for example, 60 C. to 120.degree. C., and the reaction time is preferably, for example, 30 minutes to 12 hours.
Further, a method of dropping a monomer, a chain transfer agent and a polymerization initiator into a solvent adjusted to the above reaction temperature to carry out a polymerization reaction is preferable.

<Organic solvent>
The organic solvent contained in the metal oxide nanoparticle dispersion for firing of the present invention is not particularly limited as long as it does not react with the components in the dispersion and can dissolve or disperse them. Specifically, alcohols such as methyl alcohol, ethyl alcohol, N-propyl alcohol and isopropyl alcohol; ether alcohols such as methoxy alcohol, ethoxy alcohol, methoxyethoxyethanol, ethoxyethoxyethanol and propylene glycol monomethyl ether; ethyl acetate; Esters such as butyl acetate, 3-methoxybutyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl lactate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; methoxyethyl acetate, methoxypropyl acetate, methoxybutyl Ether alcohol acetates such as acetate, ethoxyethyl acetate, ethyl cellosolve acetate, methoxyethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate; diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl Ethers such as ethyl ether and tetrahydrofuran; Aprotic amides such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone; Lactones such as γ-butyrolactone; Benzene, toluene, xylene, naphthalene organic solvents such as saturated hydrocarbons such as n-heptane, n-hexane, and n-octane;

Among these are ketone series such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; ether alcohol series such as propylene glycol monomethyl ether; methoxyethyl acetate, ethoxyethyl acetate, ethyl cellosolve acetate, methoxyethoxyethyl acetate, ethoxyethoxyethyl acetate, propylene Ether alcohol acetates such as glycol monomethyl ether acetate; Ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, propylene glycol diethyl ether; ethyl acetate, butyl acetate, 3-methoxybutyl acetate, methyl methoxypropionate, ethoxy Ester-based solvents such as ethyl propionate and ethyl lactate can be preferably used.
Among them, propylene glycol monomethyl ether acetate (PGMEA), ethyl acetate, methyl ethyl ketone, toluene, or a mixture thereof is preferable as the solvent used in the present invention from the viewpoint of dissolving agent solubility and coating suitability.

The content of the organic solvent contained in the metal oxide nanoparticle dispersion for sintering of the present invention is not particularly limited as long as it can uniformly dissolve or disperse each component of the dispersion. In the present invention, the solid content concentration of the metal oxide nanoparticle dispersion is preferably 5% by mass or more and 70% by mass or less, more preferably 7% by mass or more and 50% by mass or less, and 10% by mass. % or more and 30% by mass or less is even more preferable. When the solid content concentration of the metal oxide nanoparticle dispersion is within the above range, a viscosity suitable for coating can be obtained.

<Other ingredients>
The metal oxide nanoparticle dispersion for sintering of the present invention may optionally contain other components within a range that does not impair the effects of the present invention.
Other components include, for example, complexing agents, protective colloids, reducing agents, surfactants for improving wettability, antifoaming agents, repelling inhibitors, antioxidants, anticoagulants, ultraviolet absorbers, and the like. Additives are included.

<Method for producing metal oxide nanoparticle dispersion for firing>
In the present invention, the method for producing the metal oxide nanoparticle dispersion for sintering may be any method as long as the metal oxide nanoparticles can be well dispersed, and can be appropriately selected from conventionally known methods and used. Specifically, for example, after preparing a dispersant solution by dissolving or dispersing the dispersant in the organic solvent, the dispersant solution is mixed with metal oxide nanoparticles and, if necessary, other components. Then, by dispersing using a known stirrer, disperser, or the like, the metal oxide nanoparticle dispersion for firing of the present invention can be prepared.

<Use of metal oxide nanoparticle dispersion for firing>
The metal oxide nanoparticle dispersion for firing of the present invention is excellent in dispersibility and dispersion stability, suppresses sedimentation of the metal oxide nanoparticles, and improves the decomposability of organic components by firing treatment. , and can be suitably used for forming conductive films, dielectric films, and the like by firing. Such conductive films and dielectric films include, for example, capacitors, solid batteries, wiring boards, conductive films, electrodes, photoelectric conversion semiconductor films, various sensors, conductive films and dielectric films provided in electronic parts such as liquid crystal display elements. can be mentioned. Among them, the metal oxide nanoparticle dispersion for firing of the present invention can be suitably used, for example, for forming oxide-based solid electrolyte films such as dielectrics of laminated ceramic capacitors and ceramic solid batteries. is possible, it can be preferably used for forming a dielectric ceramic sheet (green sheet).

[Method for producing sintered film]
The method for producing a sintered film according to the present invention includes a step of applying a composition containing the metal oxide nanoparticle dispersion for firing according to the present invention on a substrate to form a coating film, and and a step of firing.

In the sintered film produced by the production method of the present invention, by using the metal oxide nanoparticle dispersion for firing according to the present invention, the aggregation and unevenness of the metal oxide nanoparticles are reduced, and the residual amount of the organic component is is a high-quality sintered film with reduced
In addition, in the present invention, the coating film is formed on a base material that serves as a support, and may be not only a continuous layer but also a discontinuous layer that is dispersed like islands. When baking a coating film formed on a substrate, the baking treatment can be performed with or without peeling the coating film from the substrate. For example, in the production of a dielectric ceramic sheet (green sheet), a release film is used as a base material, and a sheet-like coating film obtained by peeling from the release film is laminated to obtain a laminate, and the laminate is obtained. A method of sintering the body is preferred.
When the coating film is fired without being peeled off from the substrate, the sintered film formed on the substrate can be used for desired applications with or without peeling off from the substrate.

The composition containing the metal oxide nanoparticle dispersion for firing according to the present invention used in the method for producing a sintered film according to the present invention contains at least the metal oxide nanoparticle dispersion for firing according to the present invention, A baking binder resin and other components may be further contained within a range that does not impair the effects of the present invention.
Since the metal oxide nanoparticle dispersion for sintering according to the present invention is as described above, the description is omitted here.

Examples of the baking binder resin include (meth)acrylic (co)polymers. Among them, a (meth)acrylic (co)polymer obtained by polymerizing a monomer having a branched alkyl group such as isopropyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate as a polymerization component is preferable and dispersed. From the viewpoint of properties, a (meth)acrylic copolymer obtained by polymerizing a monomer having a branched alkyl group and a monomer having an acid value such as (meth)acrylic acid as polymerization components is more preferable.

Examples of the other components include those similar to the other components that may be contained in the metal oxide nanoparticle dispersion for firing of the present invention, and are appropriately selected and used depending on the application.

The substrate used in the method for producing a sintered film according to the present invention is not particularly limited, and examples thereof include resin substrates and glass substrates. A glass substrate is preferably used as a substrate that serves as a support for a sintered film, but the metal oxide nanoparticle dispersion for firing according to the present invention can be sintered at a lower temperature than before. Also, it is possible to suitably use resin substrates that have been difficult to apply to conventional sintered films. The resin base material is preferably a base material having excellent heat resistance, and specific examples thereof include polyimide resins and polyamide resins. Also, in the case of performing a firing treatment after peeling the coating film from the substrate, such as in the production of a dielectric ceramic sheet (green sheet), a release film can be preferably used as the substrate. As the release film, a known one can be used. For example, a release-treated resin film can be used, and a commercially available product may be used. Commercially available release films include, for example, release PET films (eg, product number E7006 manufactured by Toyobo Co., Ltd.).
The shape of the substrate may be appropriately selected depending on the application, and may be flat or curved. When using a flat substrate, the thickness of the substrate may be appropriately set according to the application, and may be, for example, about 25 μm or more and 100 mm or less.

As a coating method for forming a coating film by coating the composition containing the metal oxide nanoparticle dispersion for firing according to the present invention on a substrate, a conventionally known method may be appropriately selected. For example, methods such as gravure printing, screen printing, spray coating, die coating, spin coating, comma coating, bar coating, knife coating, offset printing, flexographic printing, inkjet printing, and dispenser printing can be used. Among them, gravure printing, flexographic printing, screen printing, and inkjet printing are preferable because fine patterning can be performed. In particular, the metal oxide nanoparticle dispersion for sintering of the present invention is excellent in dispersibility, and is therefore suitable for inkjet printing because it hardly causes clogging of ejection nozzles or bending of ejection.

The resulting coating film may be dried by a conventionally known method. The thickness of the film after drying may be appropriately adjusted depending on the application, but is usually in the range of 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm.

In the step of baking the obtained coating film, a conventionally known baking method may be used as the baking method, and is not particularly limited. Examples thereof include a method of raising the temperature to a temperature at which metal oxide nanoparticles are fired together, a method of using surface wave plasma generated by applying microwave energy, and the like.
The firing temperature is appropriately adjusted according to the types of metal oxide nanoparticles, dispersant and other components contained in the coating film, and is not particularly limited, but is usually in the range of 300 ° C. or higher and 600 ° C. or lower, and is preferable. is in the range of 350° C. or more and 500° C. or less.
In addition, in the structural unit represented by the general formula (I) that the dispersant has, L ¹ in the general formula (I) is --COO-- and R ² is --CH ₂ --R ²¹ . Representing a monovalent group, when R ²¹ is a hydrogen atom or an alkyl group, the dispersing agent has excellent decomposability and can be fired without leaving any residual organic matter even under an inert atmosphere.

The use of the sintered film obtained by the production method of the present invention is not particularly limited.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the invention.
In the following, the weight average molecular weight Mw and number average molecular weight Mn were confirmed by GPC (gel permeation chromatography) under the conditions of N-methylpyrrolidone, 0.01 mol/L lithium bromide addition/polystyrene standard.

(Synthesis Example 1: Synthesis of dispersant SiP01 solution)
A reactor equipped with a cooling tube, an addition funnel, a nitrogen inlet, a mechanical stirrer, and a digital thermometer was charged with 80 parts by mass of propylene glycol monomethyl ether acetate (PGMEA) as a solvent, and heated to 90°C under a nitrogen atmosphere. After that, 56.67 parts by mass of isobutyl methacrylate (iBMA) as a monomer, 0.57 parts by mass of α,α'-azobisisobutyronitrile (AIBN) as an initiator, and 3-mercaptopropyltrimethoxy as a chain transfer agent A mixture containing 2.27 parts by mass of silane (manufactured by Shin-Etsu Chemical Co., Ltd., product name KBM-803) was continuously added dropwise over 1.5 hours.
Thereafter, the synthesis temperature was maintained for 3 hours, the temperature was raised to 115° C., and the mixture was further heated for 15 minutes to obtain a dispersant SiP01 solution having a solid content of 40% by mass. The resulting dispersant SiP01 had a weight average molecular weight Mw of 7335, a number average molecular weight Mn of 5166, and a molecular weight distribution (Mw/Mn) of 1.42.

(Synthesis Examples 2 to 8: Synthesis of dispersant SiP02 solution to dispersant SiP08 solution)
Dispersant SiP02 solution to dispersant SiP08 solution were obtained in the same manner as in Synthesis Example 1 except that the type and amount of the chain transfer agent and the type of monomer were changed as shown in Table 1. . Table 1 shows the weight average molecular weight Mw, number average molecular weight Mn and molecular weight dispersity (Mw/Mn) of each dispersant obtained.

In addition, as a result of confirming the structure of each dispersant obtained in Synthesis Examples 1 to 8 by ¹ H-NMR, it was confirmed that it was a polymer compound represented by the following chemical formulas (1) to (8). was made. In the following chemical formulas (1) to (8), n1 to n8 each represent the number of repeating units.

Abbreviations in Table 1 are as follows.
KBM803: 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name KBM-803)
iBMA: isobutyl methacrylate nBMA: n-butyl methacrylate tBMA: tert-butyl methacrylate 2-EHMA: 2-ethylhexyl methacrylate iPMA: isopropyl methacrylate MMA: methyl methacrylate

(Example 1)
1.5 parts by mass of zirconia (ZrO ₂ ) particles (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., product name UEP-100, average primary particle size 30 nm) in a standard glass bottle (No. 4, capacity 37 mL), synthesis example 1.1 parts by mass of the dispersing agent SiP01 solution (solid content concentration 40% by mass) obtained in 1 (0.45 parts by mass of the dispersing agent SiP01), and 12.4 parts by mass of ethyl acetate as a solvent were blended. 15 parts by mass of zirconia beads were added and pre-dispersed for 1 hour with a paint shaker (manufactured by Asada Iron Works). Furthermore, by replacing with zirconia beads of 0.1 mm and dispersing for 6 hours, a metal oxide nanoparticle dispersion for firing (particle concentration: 10% by mass) was produced.

(Examples 2 to 13, Comparative Examples 1 to 11)
In Examples 2 to 7 and Comparative Examples 1 to 5, instead of the dispersant SiP01 solution in Example 1, the dispersant SiP02 solution to the dispersant SiP08 solution obtained in Synthesis Examples 2 to 8 or the dispersant shown in Table 2 are used to adjust the amount of the dispersant added so that the amount of the dispersant is 0.45 parts by mass, and the amount of ethyl acetate added so that the particle concentration of the resulting dispersion is 10% by mass. In the same manner as in Example 1, except for adjusting the metal oxide nanoparticle dispersions for firing of Examples 2 to 7 (particle concentration 10% by mass) and the comparative dispersions of Comparative Examples 1 to 5 (particle concentration 10 mass %) was produced.
Examples 8 to 13 were prepared in the same manner as in Example 1, except that metal oxide nanoparticles shown in Table 2 were used instead of the zirconia particles in Example 1. Metals for firing of Examples 8 to 13 were prepared. An oxide nanoparticle dispersion (particle concentration 10% by weight) was obtained.
Comparative Examples 6 to 11 were prepared in the same manner as in Comparative Example 1, except that the metal oxide nanoparticles shown in Table 2 were used instead of the zirconia particles in Comparative Example 1. Comparative dispersions of Comparative Examples 6 to 11 were prepared. (particle concentration of 10% by mass) was obtained.

(evaluation)
<Thermal decomposition evaluation>
The thermogravimetric change of the dispersant used in each example and each comparative example was measured by TG-DTA (“DTG-60A” manufactured by Shimadzu Corporation). Under the conditions of a measurement temperature of 30 to 600 ° C., about 10 mg of the dispersant is heated at 10 ° C./min in the air and in a nitrogen atmosphere, and the weight of the dispersant before heating is 100%. The temperature at which the weight was reduced by 95% (5% by weight of dispersant remaining) was taken as the decomposition temperature of the dispersant. With respect to the dispersants used in Comparative Examples 4 and 5, the decomposition temperature could not be measured because the weight of the dispersants remaining exceeded 5% even after the temperature was raised to 600°C.
Also, the residual amount of the dispersant after firing was evaluated according to the following evaluation criteria. Table 2 shows the results.
(Residual amount evaluation criteria after firing)
A: The weight of the dispersant when heated to 600°C was 0.1% or less of the weight of the dispersant before heating.
B: The weight of the dispersant when the temperature was raised to 600°C was more than 0.1% and 5% or less of the weight of the dispersant before heating.
C: The weight of the dispersant when the temperature was raised to 600°C was more than 5% and not more than 10% of the weight of the dispersant before heating.
D: The weight of the dispersant when heated to 600°C exceeded the weight of the dispersant before heating by 10%.

<Dispersibility evaluation>
In the metal oxide nanoparticle dispersion for firing obtained in each example and the comparative dispersion obtained in each comparative example, the dispersed particle size and viscosity of the metal oxide nanoparticles were measured. As the dispersed particle size, the average particle size was measured using "Nanotrack UPA-EX150" manufactured by Microtrack Bell. As the viscosity, the shear viscosity was measured at a shear rate of 60 rpm using "Rheometer MCR301" manufactured by Anton Paar. Table 2 shows the results. A comparative example in which the solvent phase and the sedimented metal oxide nanoparticle phase were phase-separated immediately after dispersion and the metal oxide nanoparticles could not be dispersed is described as “phase separation”.

<Sediment evaluation>
The metal oxide nanoparticle dispersion for firing obtained in each example and the comparative dispersion obtained in each comparative example were allowed to stand at room temperature (25 ° C.) for 1 week, and the sedimentation in the dispersion after standing The object was visually observed and evaluated according to the following evaluation criteria. Table 2 shows the results. Incidentally, the smaller the amount of sediment, the better the dispersion stability.
(Sediment evaluation criteria)
A: No sediment B: With sediment C: Phase separation

The metal oxide nanoparticles used in each example and each comparative example shown in Table 2 are as follows.
ZrO ₂ : Daiichi Kigenso Kagaku Kogyo, product name UEP-100, average primary particle size 30 nm
Al ₂ O ₃ : manufactured by Aldrich, average primary particle size <50 nm
TiO ₂ : manufactured by Tayca, brand MT-05, average primary particle size 10 nm
ITO: manufactured by CIK Nanotech, average primary particle size 30 nm
CeO ₂ : manufactured by Aldrich, average primary particle size <50 nm
ZnO: manufactured by Aldrich, average primary particle size <50 nm
BaTiO ₃ : manufactured by Sakai Chemical Industry, product name BT-01, average primary particle size 100 nm
Further, the dispersants used in Comparative Examples 2 to 5 shown in Table 2 are as follows.
Vinyltrimethoxysilane: Tokyo Chemical Industry Co., Ltd. KBM503: 3-methacryloxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd., product name KBM-503
BYK111: manufactured by BYK Chemie, product name DISPERBYK-111, phosphate ester dispersant Plysurf A208F: manufactured by Daiichi Kogyo Seiyaku, phosphate ester dispersant

From the results of Table 2, as a dispersant, a hydrolyzable silyl group represented by the general formula (II) is present at one end of the main chain of the polymer chain having the structural unit represented by the general formula (I). The metal oxide nanoparticle dispersions for firing of Examples 1 to 13 using a polymer compound are excellent in the dispersibility and dispersion stability of the metal oxide nanoparticles, there is no sedimentation of the metal oxide nanoparticles, and the dispersant The decomposition temperature of is low, the dispersant does not remain or hardly remains after heating, and the metal oxide nanoparticle dispersion for firing has improved decomposability of the organic component by firing treatment. In the metal oxide nanoparticle dispersions for firing of Examples 1 to 13, the hydrolyzable silyl groups at the ends of the polymer chains chemically adsorb to the surface of the metal oxide nanoparticles, and the polymer chains sterically repel each other. , the dispersibility and dispersion stability were excellent. Among them, in Examples 1 to 3, 5, and 7 to 13, the dispersant is completely decomposed after the calcination treatment, and the decomposition temperature of the dispersant is low. , sintering at low temperatures was possible. Among them, in Examples 1, 2, 5, 8 to 13, the decomposition temperature of the dispersant was even lower, and sintering at a lower temperature was possible. Further, from a comparison between Example 1 and Example 2, when the specific dispersant having a weight average molecular weight Mw of 2000 or more and 4000 or less is used, the dispersed particle size of the metal oxide nanoparticles and the viscosity of the dispersion It was found that the amount was further decreased and the dispersibility was further improved.
Comparative Examples 1 and 6 to 11 have a dodecyl group instead of a hydrolyzable silyl group at one end of the main chain of the polymer chain having the structural unit represented by the general formula (I) as a dispersant. Since the polymer compound was used, the metal oxide nanoparticles could not be dispersed, and the metal oxide nanoparticles precipitated and phase-separated.
In Comparative Examples 2 and 3, since a low-molecular-weight silane coupling agent was used as the dispersant, the metal oxide nanoparticles could not be dispersed, and the metal oxide nanoparticles precipitated and phase-separated. In Comparative Examples 2 and 3, because the molecular weight of the dispersant was too small, it was considered that the sedimentation of the metal oxide nanoparticles due to steric repulsion could not be suppressed, or that the silane coupling agents aggregated due to a condensation reaction between themselves. be done.
In Comparative Examples 4 and 5, a phosphoric acid ester-based dispersant was used as the dispersant, and sedimentation of metal oxide nanoparticles occurred over time. This is probably because the phosphoric acid ester-based dispersant does not have sufficient adsorptive power of the phosphate group and has a low molecular weight. In addition, phosphate ester-based dispersants are not suitable for firing because the phosphoric acid group remains without being decomposed even after firing, so the amount of organic components remaining after firing tends to increase. It became clear.

(Examples 14-18)
In Examples 14 to 18, metal oxide nanoparticles of barium titanate or barium zirconate titanate, which are preferably used as ceramic dielectrics in multilayer ceramic capacitor applications, were used, and metal oxide nanoparticles for firing with an increased particle concentration were used. Particle dispersions were prepared and evaluated for dispersibility.
In Examples 14 to 18, in place of the zirconia particles in Example 1, as shown in Table 3, barium titanate particles A (manufactured by Sakai Chemical Industry, product name BT-01, average primary particle size 100 nm), titanium Using barium acid particles B (manufactured by Sakai Chemical Industry, product name KZM-50, average primary particle diameter 50 nm) or barium zirconate titanate particles (manufactured by Sakai Chemical Industry, product name BZT-01, average primary particle diameter 50 nm), Instead of 1.1 parts by mass of the dispersant SiP01 solution, a dispersant solution of the dispersant shown in Table 3 was added to the ratio (D / P) of the mass (D) of the dispersant and the mass (P) of the metal oxide nanoparticles. Firing of Examples 14 to 18 in the same manner as in Example 1, except that the added amount of ethyl acetate was adjusted so that the particle concentration shown in Table 3 was obtained. A dispersion of metal oxide nanoparticles for

The metal oxide nanoparticle dispersions for firing obtained in Examples 14 to 18 were evaluated in the same manner as the dispersibility evaluation and the sediment evaluation. Table 3 shows the results.

From the results of Table 3, in the metal oxide nanoparticle dispersion for firing of the present invention using the specific dispersant, both metal oxide nanoparticles having an average primary particle size of 50 nm or 100 nm can be dispersed up to about 60 nm. , and it was found that excellent dispersibility and dispersion stability are exhibited even when the concentration of the metal oxide nanoparticles is increased to 50% by mass.

Claims (4)

containing metal oxide nanoparticles, a dispersant, and an organic solvent,
The dispersant is a polymer compound having a hydrolyzable silyl group represented by the following general formula (II) at one end of the main chain of a polymer chain having a structural unit represented by the following general formula (I). the law of nature,
The average particle size of the metal oxide nanoparticles is 10 nm or more and 200 nm or less,
Metal oxide nanoparticle dispersion for sintering.

(In general formula (I), R ¹ is a hydrogen atom or a methyl group, L ¹ is a —COO— group , R ² is a monovalent group —CH ₂ —R ²¹ , and R ²¹ is hydrogen represents an alkyl group having atoms or carbon atoms of 1 to 17. )

(In general formula (II), R ³ and R ⁴ are each independently a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms ; L ² is an ether group (-O- group), a thioether group (- S— group), —COO— group, and a combination of at least one selected from these groups and a divalent hydrocarbon group having 1 to 10 carbon atoms, and m is an integer of 1 to 3 represents.) 2. The metal oxide nanoparticle dispersion for firing according to claim 1 , wherein said ^R21 is a branched alkyl group. The metal oxide nanoparticles have, on at least their surface, zirconium oxide, aluminum oxide, titanium oxide, indium oxide, indium tin oxide, zinc oxide, cerium oxide, barium titanate, barium zirconate, barium zirconate titanate and titanium. 3. The metal oxide nanoparticle dispersion for firing according to claim 1 , comprising at least one metal oxide selected from the group consisting of strontium oxide. A step of applying a composition containing the metal oxide nanoparticle dispersion for firing according to any one of claims 1 to 3 on a substrate to form a coating film, and firing the coating film. A method for producing a sintered film, comprising: