Adhesive composition for dielectric layer, slurry composition for dielectric layer, dielectric layer, and capacitor

Abstract

The purpose of the present invention is to provide an adhesive composition for dielectric layers, which is capable of imparting excellent blocking resistance and transferability to a dielectric layer. This adhesive composition for a dielectric layer contains a particulate polymer and water, and the particulate polymer contains a (meth) acrylate monomer unit.

Description

Technical Field

[0001] The present invention relates to an adhesive composition for a dielectric layer, a slurry composition for a dielectric layer, a dielectric layer, and a capacitor. Background Art

[0002] Capacitors such as multilayer ceramic capacitors can generally be obtained by forming dielectric layers such as ceramic green sheets, stacking the dielectric layers, and arbitrarily sintering them.

[0003] The dielectric layer can be obtained, for example, by first preparing a slurry composition comprising a binder, a dielectric material, and a solvent, then applying the slurry composition onto a release substrate, and then drying the slurry composition. The resulting dielectric layer is then used in the manufacture of a capacitor.

[0004] In recent years, in order to impart excellent characteristics to capacitors, binders included in slurry compositions for producing dielectric layers have been developed.

[0005] For example, Patent Document 1 proposes an adhesive for producing an inorganic sintered body, which comprises an adhesive resin composition having a specified gel fraction and containing a specified composite resin. When used as an adhesive for preparing ceramic green sheets, the adhesive can produce ceramic green sheets that can achieve a high porosity and are not prone to defects such as cracks when producing sintered bodies, and has excellent thermal decomposition properties.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-165230. Summary of the Invention

[0009] Problems to be solved by the invention

[0010] After a dielectric layer, such as a ceramic green sheet, is formed on a release substrate, it is typically wound into a roll along with the release substrate. When wound into a roll, the dielectric layer comes into close contact with the surface of the release substrate on which the dielectric layer is not formed (hereinafter sometimes referred to as the "back side of the release substrate"). If stored in this state, the dielectric layer may adhere to the back side of the release substrate (so-called blocking), potentially causing fractures in the dielectric layer.

[0011] Furthermore, in capacitor manufacturing, after forming a dielectric layer on a release substrate, the dielectric layer is typically stacked with other layers and pressed. When the dielectric layer is subsequently peeled from the release substrate, there is a risk that the dielectric layer may remain on the release substrate.

[0012] Solutions for solving problems

[0013] The present inventors have conducted intensive research to solve the above-mentioned problems and have newly discovered that the above-mentioned problems can be solved by using a dielectric layer adhesive composition comprising a particulate polymer containing predetermined monomer units and water, thereby completing the present invention.

[0014] That is, the object of the present invention is to advantageously solve the above-mentioned problems. [1] The present invention is an adhesive composition for a dielectric layer, comprising a particulate polymer containing a (meth)acrylate monomer unit and water.

[0015] Use of the above-described adhesive composition for a dielectric layer can impart excellent anti-blocking properties to the dielectric layer.

[0016] Furthermore, the use of the above-described dielectric layer adhesive composition can prevent the dielectric layer from remaining on the release substrate when the dielectric layer is peeled from the release substrate after laminating the dielectric layer with other layers and applying pressure during capacitor production. In other words, the use of the above-described dielectric layer adhesive composition can impart excellent transferability to the dielectric layer.

[0017] Furthermore, since the above-mentioned adhesive composition for a dielectric layer contains water as a solvent, the use of such an adhesive composition can reduce the environmental load and improve safety in the production of capacitors.

[0018] In addition, whether the granular polymer contains the specified monomer units can be used 1 The determination is made by nuclear magnetic resonance (NMR) methods such as H-NMR. In addition, the phrase "a particulate polymer contains a monomer unit" means that "a particulate polymer obtained using the monomer contains a repeating unit derived from the monomer."

[0019] Furthermore, in the present invention, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0020] [2] In the adhesive composition for a dielectric layer according to [1] above, the glass transition temperature of the particulate polymer is preferably -50°C or higher and 20°C or lower.

[0021] When the glass transition temperature is at least the above lower limit, the anti-blocking property of the dielectric layer can be improved. Furthermore, when the glass transition temperature is at most the above upper limit, the transferability of the dielectric layer can be improved.

[0022] In the present invention, the glass transition temperature of the particulate polymer can be measured by the method described in Examples.

[0023] [3] In the adhesive composition for a dielectric layer according to [1] or [2], the volume average particle size of the particulate polymer is preferably 0.01 μm or more and 1.0 μm or less.

[0024] If the volume average particle size of the particulate polymer is greater than or equal to the above lower limit, the transferability of the dielectric layer can be improved. Furthermore, if the volume average particle size of the particulate polymer is greater than or equal to the above lower limit, the dielectric layer formed on the release substrate can be prevented from unexpectedly peeling from the release substrate. In other words, the use of the above-described adhesive composition for a dielectric layer can impart excellent adhesion to the dielectric layer.

[0025] On the other hand, when the volume average particle size of the particulate polymer is equal to or smaller than the upper limit value described above, the anti-blocking property of the dielectric layer can be improved.

[0026] In the present invention, the volume average particle size of the particulate polymer can be measured by the method described in Examples.

[0027] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. [4] The present invention is a slurry composition for a dielectric layer, comprising the adhesive composition for a dielectric layer according to any one of [1] to [3] above, a dielectric material, and a solvent.

[0028] The use of the above-mentioned slurry composition for a dielectric layer can impart excellent anti-blocking properties and transfer properties to the dielectric layer. Furthermore, the use of the above-mentioned slurry composition for a dielectric layer can impart excellent adhesion to the dielectric layer.

[0029] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. [5] The present invention provides a dielectric layer obtained by drying a coating film formed from the slurry composition for a dielectric layer according to [4] above.

[0030] The dielectric layer has excellent anti-blocking properties, transferability, and adhesiveness. Moreover, due to the excellent anti-blocking properties, transferability, and adhesiveness of the dielectric layer, it is easy to handle, resulting in efficient production of capacitors.

[0031] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. [6] The present invention is a capacitor formed using the dielectric layer of [5] above.

[0032] The above capacitor has excellent productivity because it uses a dielectric layer that is easy to handle.

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide an adhesive composition for a dielectric layer that can impart excellent anti-blocking properties and transferability to a dielectric layer.

[0035] Furthermore, according to the present invention, a slurry composition for a dielectric layer capable of imparting excellent anti-blocking properties and transferability to a dielectric layer can be provided.

[0036] Furthermore, according to the present invention, there can be provided a dielectric layer obtained by drying a coating film formed from the above-mentioned slurry composition for a dielectric layer.

[0037] Furthermore, according to the present invention, it is possible to provide a capacitor formed using the above-mentioned dielectric layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic cross-sectional view showing an example of a multilayer ceramic capacitor as the capacitor of the present invention. DETAILED DESCRIPTION

[0039] Hereinafter, embodiments of the present invention will be described in detail.

[0040] Here, the adhesive composition for dielectric layer of the present invention (hereinafter, sometimes referred to as "adhesive composition") can be used to prepare the slurry composition for dielectric layer of the present invention (hereinafter, sometimes referred to as "slurry composition"). Moreover, the slurry composition of the present invention can be used to form a dielectric layer used in the manufacture of capacitors, etc. Furthermore, the dielectric layer of the present invention is formed by drying a coating film formed from the slurry composition of the present invention. In addition, the capacitor of the present invention is formed using a dielectric layer, and the above-mentioned dielectric layer is formed using the slurry composition of the present invention.

[0041] (Adhesive composition for dielectric layer)

[0042] The adhesive composition for a dielectric layer of the present invention comprises a granular polymer and water as a solvent, and may optionally contain components other than the granular polymer and water (hereinafter sometimes referred to as "other components"). Furthermore, in the adhesive composition of the present invention, the granular polymer contains (meth)acrylate monomer units. Using such an adhesive composition can impart excellent anti-blocking properties and transferability to the dielectric layer.

[0043] In this specification, the adhesive composition generally does not contain a dielectric material described below.

[0044] <Granular Polymer>

[0045] The particulate polymer contained in the adhesive composition of the present invention is a component capable of functioning as a binder and comprises (meth)acrylate monomer units and may optionally comprise acid group-containing monomer units. Furthermore, the particulate polymer may comprise monomer units other than (meth)acrylate monomer units and acid group-containing monomer units (hereinafter sometimes referred to as "other monomer units").

[0046] In the present invention, the polymer being "water-insoluble" means that when 0.5 g of the polymer is dissolved in 100 g of water at 25°C, the insoluble content is 90% by mass or more.

[0047] <<(Meth)acrylate monomer unit>>

[0048] (Meth) acrylic acid ester monomer unit is a monomer unit that can be formed by (meth) acrylic acid ester monomer. As (meth) acrylic acid ester monomer, can enumerate methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate and other (meth) acrylic acid alkyl esters etc..These can be used alone or in combination of two or more.Among these, as (meth) acrylic acid ester monomer, preferably ethyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, more preferably ethyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate.

[0049] In addition, in the present invention, "(meth)acrylate" means acrylate and / or methacrylate.

[0050] When all repeating units (all monomer units) contained in the particulate polymer are taken as 100 mass%, the content ratio of the (meth)acrylate monomer unit is preferably 50 mass% or more, more preferably 55 mass% or more, and is preferably 98 mass% or less, more preferably 95 mass% or less.

[0051] When the content of the (meth)acrylate monomer units is at least the above lower limit, the adhesiveness and transferability of the dielectric layer can be improved.

[0052] On the other hand, when the content ratio of the (meth)acrylate monomer units is equal to or less than the above upper limit, the anti-blocking property of the dielectric layer can be improved.

[0053] <<Acid group-containing monomer unit>>

[0054] The acid group-containing monomer unit is a monomer unit that can be formed from an acid group-containing monomer. Examples of the acid group-containing monomer include carboxylic acid group-containing monomers and sulfonic acid group-containing monomers.

[0055] Examples of the carboxylic acid group-containing monomer include monocarboxylic acids and derivatives thereof, dicarboxylic acids and anhydrides thereof, and derivatives thereof.

[0056] Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid.

[0057] Examples of the monocarboxylic acid derivative include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, and α-chloro-β-E-methoxyacrylic acid.

[0058] Examples of the dicarboxylic acid include maleic acid, fumaric acid, and itaconic acid.

[0059] Examples of the dicarboxylic acid derivatives include maleic acid monoesters such as methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, butyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate.

[0060] Examples of the anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, and citraconic anhydride.

[0061] Furthermore, as the carboxylic acid group-containing monomer, an acid anhydride that generates a carboxylic acid group by hydrolysis can also be used.

[0062] Furthermore, as the carboxylic acid group-containing monomer, ethylenically unsaturated polycarboxylic acids such as butenetricarboxylic acid, partial esters of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate and mono-2-hydroxypropyl maleate, and the like can also be used.

[0063] Examples of the sulfonic acid group-containing monomer include vinylsulfonic acid (ethylenesulfonic acid), methylvinylsulfonic acid, (meth)allylsulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

[0064] In addition, in this specification, "(meth)allyl group" means an allyl group and / or a methallyl group.

[0065] As the acid group-containing monomer, acrylic acid, methacrylic acid, itaconic acid and vinylsulfonic acid are preferred.

[0066] When all repeating units (all monomer units) contained in the particulate polymer are taken as 100 mass%, the content ratio of the acid group-containing monomer unit is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and preferably 10 mass% or less, more preferably 5 mass% or less.

[0067] If the content of the acid group-containing monomer units is greater than the above lower limit, the dispersion stability of the particulate polymer in the adhesive composition and the slurry composition can be improved. In addition, if the content of the acid group-containing monomer units is greater than the above lower limit, the anti-blocking properties of the dielectric layer can be improved.

[0068] On the other hand, when the content ratio of the acid group-containing monomer units is equal to or less than the above upper limit, the transferability of the dielectric layer can be improved.

[0069] <<Other monomer units>

[0070] The other monomer units are monomer units that can be formed from other monomers. The other monomers are not particularly limited as long as they are copolymerizable with the above-mentioned monomers.

[0071] Furthermore, other monomer units are preferably aromatic vinyl monomer units, cyano group-containing monomer units, and conjugated diene monomer units.

[0072] <<Aromatic vinyl monomer unit>>

[0073] The aromatic vinyl monomer unit is a monomer unit that can be formed from an aromatic vinyl monomer. Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene, and divinylbenzene. These can be used alone or in combination of two or more. Among these, styrene is preferred as the aromatic vinyl monomer.

[0074] <<Cyanide-containing monomer unit>>

[0075] The cyano group-containing monomer unit is a monomer unit that can be formed from a cyano group-containing monomer. Examples of cyano group-containing monomers include acrylonitrile and methacrylonitrile. These may be used alone or in combination of two or more in any ratio. Among these, acrylonitrile is preferred as the cyano group-containing monomer.

[0076] <<Conjugated diene monomer unit>>

[0077] The conjugated diene monomer unit is a monomer unit that can be formed from a conjugated diene monomer. As a conjugated diene monomer, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, substituted straight-chain conjugated pentadienes, substituted and side-chain conjugated hexadienes, etc. can be cited. These can be used alone or in combination of two or more. Among these, as a conjugated diene monomer, preferably 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene), more preferably 1,3-butadiene.

[0078] Other monomers that can be used, in addition to the monomers listed above, include: amide-containing monomers such as acrylamide and methacrylamide; crosslinking monomers (crosslinkable monomers) such as allyl glycidyl ether, allyl (meth)acrylate, and N-methylol acrylamide; olefins such as ethylene and propylene; halogen-containing monomers such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl butyrate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; heterocyclic vinyl compounds such as N-vinylpyrrolidone, vinylpyridine, and vinylimidazole; and amino-containing monomers such as aminoethyl vinyl ether and dimethylaminoethyl vinyl ether. These other monomers may be used alone or in combination of two or more.

[0079] When all repeating units (all monomer units) contained in the particulate polymer are set to 100 mass%, the content ratio of other monomer units is preferably 1 mass% or more, more preferably 5 mass% or more, and preferably 40 mass% or less, more preferably 35 mass% or less.

[0080] <<Properties of Granular Polymer>>

[0081] In the adhesive composition of the present invention, the glass transition temperature of the particulate polymer is preferably -50°C or higher, more preferably -45°C or higher, and is preferably 20°C or lower, more preferably 15°C or lower.

[0082] When the glass transition temperature of the particulate polymer is -50°C or higher, the blocking resistance of the dielectric layer can be improved.

[0083] On the other hand, when the glass transition temperature of the particulate polymer is 20° C. or lower, the transferability of the dielectric layer can be improved.

[0084] The tetrahydrofuran (THF) insoluble content of the particulate polymer is preferably 70% by mass or more, more preferably 75% by mass or more, and is preferably 100% by mass or less, more preferably 98% by mass or less.

[0085] When the THF-insoluble content of the particulate polymer is at least the above lower limit, the anti-blocking property of the dielectric layer can be improved.

[0086] On the other hand, when the THF-insoluble content of the particulate polymer is equal to or less than the upper limit value described above, the adhesiveness and transferability of the dielectric layer can be improved.

[0087] In the present invention, the THF-insoluble content of the particulate polymer can be measured by the method described in Examples.

[0088] In the adhesive composition, the volume average particle size of the particulate polymer is preferably 0.01 μm or more, more preferably 0.02 μm or more, and is preferably 1.0 μm or less, more preferably 0.5 μm or less.

[0089] When the volume average particle size of the particulate polymer is equal to or greater than the above lower limit, the adhesiveness and transferability of the dielectric layer can be improved.

[0090] On the other hand, when the volume average particle size of the particulate polymer is equal to or smaller than the upper limit value described above, the anti-blocking property of the dielectric layer can be improved.

[0091] <<Polymerization Method of Granular Polymer>>

[0092] The polymerization method for the particulate polymer is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization can be used. Furthermore, as the polymerization reaction, addition polymerization such as ionic polymerization, free radical polymerization, or living free radical polymerization can be used. Furthermore, additives such as polymerization solvents, emulsifiers, dispersants, polymerization initiators, and chain transfer agents that can be used in the polymerization can be commonly used, and their amounts can also be commonly used.

[0093] <Solvent>

[0094] The adhesive composition of the present invention contains water as a solvent. By using an adhesive composition containing water as a solvent, the environmental load can be reduced and the safety can be improved in the production of capacitors.

[0095] In addition, the adhesive composition of the present invention may optionally contain an aqueous organic solvent as a solvent in addition to water. Examples of aqueous organic solvents include lower alcohols such as methanol, ethanol, and isopropyl alcohol. The proportion of water in the solvent is typically 50% by mass or greater, preferably 80% by mass or greater, more preferably 90% by mass or greater, and even more preferably 100% by mass (i.e., the solvent is solely water).

[0096] <Other ingredients>

[0097] The adhesive composition of the present invention may contain other components. Examples of other components include the additives used when polymerizing the particulate polymer, viscosity modifiers, and the like. In addition, polyvinyl butyral and the like can be used as viscosity modifiers.

[0098] <Solid Content Concentration of Adhesive Composition for Dielectric Layer>

[0099] The solid content concentration of the adhesive composition is preferably 20% by mass or more, preferably 30% by mass or more, and preferably 60% by mass or less, and more preferably 50% by mass or less.

[0100] <Method for Preparing Adhesive Composition for Dielectric Layer>

[0101] The adhesive composition of the present invention can be prepared by mixing the above-mentioned particulate polymer, solvent, and any other ingredients using a known method. Specifically, the adhesive composition can be prepared by mixing the above-mentioned ingredients using a mixer such as a ball mill, sand mill, bead mill, pigment disperser, attritor, ultrasonic disperser, homogenizer, planetary mixer, FILMIX, or rotary / revolving mixer.

[0102] (Slurry composition for dielectric layer)

[0103] The slurry composition for dielectric layer of the present invention comprises the above-mentioned adhesive composition of the present invention, dielectric material and solvent. That is, the slurry composition of the present invention comprises a granular polymer, a solvent containing water and a dielectric material. Here, the solvent contained in the slurry composition may be a solvent entirely from the adhesive composition, or a solvent newly added to the slurry composition in addition to the solvent from the adhesive composition. The slurry composition of the present invention may also comprise components other than the granular polymer, dielectric material and solvent (hereinafter sometimes referred to as "other components").

[0104] Furthermore, the slurry composition of the present invention, because it contains the binder composition of the present invention, can impart excellent anti-blocking properties and transfer properties to the dielectric layer. Furthermore, the slurry composition of the present invention, because it contains the binder composition of the present invention, can impart excellent adhesion to the dielectric layer.

[0105] <Dielectric Materials>

[0106] As a dielectric material, as long as it is a material with dielectric properties, it is not particularly limited, and preferably a ceramic material is used. As a ceramic material, for example, zirconium oxide, aluminum silicate, titanium oxide, zinc oxide, barium titanate, calcium zirconate, calcium titanate, strontium titanate, magnesium oxide, sialon, spinel mullite, silicon carbide, silicon nitride, aluminum nitride, etc. can be mentioned. These ceramic materials can be used alone or in combination of two or more.

[0107] Here, as the ceramic material, a ceramic material having a perovskite structure represented by the general formula ABO3 as the main phase is preferred. Examples of such ceramic materials include barium titanate (BaTiO3), calcium zirconate (CaZrO3), calcium titanate (CaTiO3), strontium titanate (SrTiO3), BaTiO3, which forms a perovskite structure, and 1-x-y Ca x Sr y Ti 1-z Zr zO3 (0≤x≤1, 0≤y≤1, 0≤z≤1), etc. Among these, barium titanate is preferred as a ceramic material having a perovskite structure as a main phase.

[0108] The volume average particle size of the dielectric material is preferably 0.01 μm or more, more preferably 0.02 μm or more, further preferably 0.05 μm or more, further preferably 0.08 μm or more, preferably 1 μm or less, more preferably 0.8 μm or less, further preferably 0.5 μm or less, further preferably 0.3 μm or less, and further preferably 0.2 μm or less.

[0109] When the volume average particle size of the dielectric material is within the above range, the dispersibility and dispersion stability of the dielectric material in the slurry composition can be improved, and as a result, a dielectric layer in which the dielectric material is uniformly dispersed can be produced.

[0110] In the present invention, the volume average particle size of the dielectric material refers to a particle size at which the cumulative volume calculated from the smallest particle size in a particle size distribution (volume basis) measured by laser diffraction method accounts for 50%.

[0111] When all components (including the solvent) in the slurry composition are taken as 100 mass %, the content ratio of the dielectric material in the slurry composition is preferably 40 mass % or more, more preferably 50 mass % or more, and preferably 80 mass % or less, more preferably 70 mass % or less.

[0112] <Solvent>

[0113] Examples of the solvent contained in the slurry composition of the present invention include the same solvents as those described in the item “Solvent” of the “Adhesive composition for a dielectric layer”.

[0114] The solvent contained in the slurry composition of the present invention is not particularly limited, and the same solvents as those described in the "Solvent" section of the "Dielectric Layer Adhesive Composition" above, as well as any non-aqueous organic solvents, can be used. Examples of the non-aqueous organic solvent include methylbenzene (toluene) and xylene.

[0115] The solvent is preferably water or an aqueous solvent from the viewpoint of improving the anti-blocking property and transferability of the dielectric layer, and is particularly preferably water from the viewpoint of reducing environmental load, safety, and easy availability.

[0116] <Other ingredients>

[0117] As other components that can be contained in the slurry composition of the present invention, the same other components as those described in the item “other components” of the above-mentioned “adhesive composition for a dielectric layer” can be mentioned.

[0118] Here, when a viscosity modifier is used as another component, the content (solid content) of the viscosity modifier in the slurry composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the dielectric material in the slurry composition.

[0119] <Solid Content Concentration of Dielectric Layer Slurry Composition>

[0120] The solid content concentration of the slurry composition is preferably 20% by mass or more, preferably 25% by mass or more, preferably 90% by mass or less, and more preferably 80% by mass or less.

[0121] <Content of granular polymer>

[0122] When the dielectric material in the slurry composition is 100 parts by mass, the content (solid content) of the particulate polymer in the slurry composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less.

[0123] <Method for Preparing Dielectric Layer Slurry Composition>

[0124] The slurry composition can be prepared by mixing the components described above using a known mixing method. Examples of the mixer used for the preparation include the mixers listed in the above-mentioned "Method for Preparing the Adhesive Composition for a Dielectric Layer."

[0125] (Dielectric layer)

[0126] The dielectric layer of the present invention is formed by drying a coating film formed from the slurry composition of the present invention. The dielectric layer of the present invention is typically a dried film obtained by partially or completely removing the solvent from a coating film formed from the slurry composition of the present invention. Specifically, the dielectric layer of the present invention comprises the above-mentioned particulate polymer and dielectric material, and optionally contains a solvent and other components.

[0127] The dielectric layer of the present invention is formed by drying a coating film formed from the slurry composition of the present invention, and therefore has excellent anti-blocking, adhesion, and transfer properties. Furthermore, due to the excellent anti-blocking, adhesion, and transfer properties of the dielectric layer of the present invention, it is easy to handle, resulting in efficient production of capacitors.

[0128] When all components in the dielectric layer are taken as 100 mass %, the content ratio of the dielectric material in the dielectric layer is preferably 70 mass % or more, more preferably 80 mass % or more, further preferably 85 mass % or more, and preferably 98 mass % or less, more preferably 95 mass % or less.

[0129] The content of the particulate polymer in the dielectric layer is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, based on 100 parts by mass of the dielectric material in the dielectric layer.

[0130] The thickness of the dielectric layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 10 μm or less, more preferably 5 μm or less.

[0131] The dielectric layer of the present invention can be formed with a conductive layer on the dielectric layer. The conductive layer can be formed using various printing methods, including screen printing, gravure printing, stamp printing, inkjet printing, and offset printing using patterns formed by these methods; and vacuum deposition methods for forming metal vapor-deposited films.

[0132] When the conductor layer is formed by printing, a conductive paste can be used. The conductive paste can be prepared by a conventionally known method, for example, by mixing conductive powder such as metal, a dispersant, a plasticizer, a solvent, etc., with polyvinyl acetal resin.

[0133] <Method for Producing Dielectric Layer>

[0134] The dielectric layer can be produced by applying the slurry composition of the present invention on a release substrate and drying the formed coating film.

[0135] Here, the release substrate used when forming the dielectric layer is formed of a flexible resin. By forming the release substrate from a flexible resin, the release substrate (laminated film) on which the dielectric layer is formed can be stored in a rolled state and supplied as needed. The dielectric layer is obtained by applying the slurry composition on the release substrate and drying it.

[0136] The release substrate is not particularly limited, and examples thereof include substrates made of resins such as polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, and polyvinyl chloride.

[0137] The release substrate is preferably subjected to a surface treatment for improving releasability on the side on which the dielectric layer of the present invention is formed. The surface treatment is not particularly limited, and examples thereof include surface treatment using a release agent such as a silicone release agent, a fluorine release agent, or a wax release agent.

[0138] The thickness of the release substrate is not particularly limited, but is usually 20 μm or more and 100 μm or less.

[0139] The method for applying the slurry composition to the release substrate is not particularly limited, and examples thereof include known coating methods using an applicator, various roll coaters such as a gravure coater and a notch wheel coater (registered trademark), and the like.

[0140] The method for drying the coating film formed on the release substrate is not particularly limited, and examples thereof include known drying methods using a hot air dryer. Drying conditions can be appropriately set depending on the solvent content in the coating film, the thickness of the coating film, and other factors. The drying temperature is generally 80°C to 150°C, and the drying time is generally 3 minutes to 60 minutes.

[0141] In addition, when the dielectric layer of the present invention is used in the manufacture of a capacitor, heat compression bonding can be performed after stacking multiple dielectric layers, and the dielectric layer can be peeled off from the above-mentioned release substrate before or after the stacking and heat compression bonding of the dielectric layers.

[0142] (Capacitor)

[0143] The capacitor of the present invention is a capacitor formed using the dielectric layer of the present invention. The capacitor of the present invention has excellent productivity because it uses a dielectric layer that is easy to handle.

[0144] Here, examples of the capacitor of the present invention include a capacitor obtained by sintering a laminated body composed of stacked dielectric layers (sintered product), and a capacitor obtained by not sintering a laminated body composed of stacked dielectric layers (unsintered product).

[0145] Examples of capacitors formed by sintering the above-mentioned laminate include multilayer ceramic capacitors.

[0146] Examples of capacitors obtained without sintering the laminate include multilayer metallized film capacitors.

[0147] In the following description, a case where the capacitor is a multilayer ceramic capacitor is used as an example. However, the present invention is not limited to the following example.

[0148] The multilayer ceramic capacitor as the capacitor of the present invention generally has a layered dielectric, a layered internal electrode, and an external electrode, and the dielectric is formed by sintering the stacked dielectric layers of the present invention. Figure 1 , an example of a multilayer ceramic capacitor as the capacitor of the present invention is described.

[0149] Figure 1 This is a schematic cross-sectional view showing an example of a multilayer ceramic capacitor as the capacitor of the present invention. Figure 1 The multilayer ceramic capacitor 10 shown has alternately stacked layered dielectrics 11 and layered internal electrodes 12, and a pair of external electrodes 13 on the outside of the dielectrics 11 and the internal electrodes 12. Moreover, one of the pair of internal electrodes 12 adjacent to each other and sandwiching the dielectric 11 in the stacking direction is electrically connected to one of the pair of external electrodes 13 inside the multilayer ceramic capacitor 10, and the other of the pair of internal electrodes 12 adjacent to each other and sandwiching the dielectric 11 in the stacking direction is electrically connected to the other of the pair of external electrodes 13 inside the multilayer ceramic capacitor 10. As a result, a structure in which a plurality of capacitor elements are electrically connected in parallel is formed between the pair of external electrodes 13. In addition, the interface between the dielectric layers that can be formed when the dielectric layers of the present invention are overlapped will disappear due to the integration of the dielectric layers by sintering, so it is not in the Figure 1 Shown in.

[0150] The multilayer ceramic capacitor is not particularly limited and can be manufactured using conventionally known methods. For example, a multilayer ceramic capacitor can be manufactured by stacking a plurality of dielectric layers of the present invention, each having a conductive layer that can serve as an internal electrode, in an alternating pattern of dielectric layers and conductive layers, heating and pressing the layers together to form a laminate, thermally decomposing and removing the binder component and the like contained in the laminate (degreasing), sintering the laminate, and then forming external electrodes on the end faces of the resulting ceramic sintered product.

[0151] The degreasing treatment is usually performed in a nitrogen atmosphere at a temperature of 300° C. to 500° C. The degreasing treatment time is usually 1 hour to 5 hours.

[0152] The content of the binder component in the laminate after degreasing is usually 50 ppm or less.

[0153] The sintering of the degreased laminate is usually carried out at an oxygen partial pressure of 10 -9 ~10 -12 The sintering is carried out in a reducing atmosphere such as H2-N2-H2O gas at a temperature of 1000° C. to 1500° C. The sintering time of the laminate is usually 1 hour to 30 hours.

[0154] The external electrodes can be formed by applying the external electrode material to the end surface of the ceramic sintered product obtained by sintering and then firing it. Figure 1 The capacitor shown is a multilayer ceramic capacitor.

[0155] Examples of external electrode materials include Cu paste containing glass frit. Firing is typically performed in a nitrogen atmosphere at a temperature between 500°C and 1500°C. The surfaces of the external electrodes may also be plated with Ni, Sn, or the like.

[0156] Example

[0157] Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to these Examples. In the following description, "%" and "parts" showing amounts are based on mass unless otherwise specified.

[0158] In addition, in a granular polymer produced by polymerizing multiple monomers, the proportion of monomer units formed by polymerizing a certain monomer in the granular polymer is usually consistent with the ratio (feed ratio) of the monomer in all monomers used for the polymerization of the granular polymer, unless otherwise specified.

[0159] Furthermore, in Examples and Comparative Examples, the glass transition temperature of the particulate polymer, the volume average particle size of the particulate polymer, the THF insoluble content of the particulate polymer, the anti-blocking property, the transferability, and the adhesiveness were measured and evaluated by the following procedures.

[0160] <Glass Transition Temperature of Granular Polymer>

[0161] The dispersions (solutions) of the particulate polymers prepared in the Examples and Comparative Examples were dried for 3 days at 50% humidity and 25°C to obtain films with a thickness of 1.0 mm. The films were then dried in a vacuum dryer at 60°C for 10 hours. The dried films were then used as samples to measure the glass transition temperature (°C) using a differential scanning calorimeter (DSC6220SII, manufactured by Nano Science Co., Ltd.) in accordance with JIS K7121, at a temperature range of -100°C to 180°C and a heating rate of 5°C / minute.

[0162] <Volume Average Particle Diameter of Granular Polymer>

[0163] The volume average particle size of the particulate polymer is measured by laser diffraction as follows.

[0164] First, dispersions of the particulate polymers prepared in the Examples and Comparative Examples were adjusted to a solids concentration of 0.1% by mass to prepare measurement samples. Then, in the particle size distribution (volume basis) measured using a laser diffraction particle size distribution analyzer (Beckman Coulter, product name "LS-230"), the volume average particle size (D50) at which the cumulative volume, calculated from the smallest particle size, reaches 50% was defined as the volume average particle size.

[0165] <THF-Insoluble Content Ratio of Granular Polymer>

[0166] The dispersions (solutions) of the particulate polymers prepared in the Examples and Comparative Examples were dried at 50% humidity and 23-25°C to form films with a thickness of approximately 0.3 mm. The films were cut into 3 mm squares and accurately weighed. The mass of the resulting film was designated w0.

[0167] The membrane was immersed in 100 g of tetrahydrofuran (THF) at 25° C. for 24 hours. The membrane was then pulled out of THF and vacuum-dried at 105° C. for 3 hours, and the mass w1 of the insoluble component was measured.

[0168] Then, the THF insoluble content (mass %) was calculated according to the following formula (1).

[0169] THF insoluble content (mass %) = (w1 / w0) × 100 (1)

[0170] <Anti-blocking properties>

[0171] The dielectric layer was peeled off from the release substrate with the dielectric layer produced in the examples and comparative examples, and the peeled dielectric layer was cut into a square of 5 cm wide x 5 cm long to prepare a test piece. A polyethylene terephthalate (PET) film was prepared, and the PET film and the test piece (dielectric layer) were overlapped and subjected to a pressure of 40°C and 10 kg / cm 2 After 24 hours, the dielectric layer was placed under pressure. The adhesion (blocking state) of the dielectric layer to the PET film was visually confirmed, and the anti-blocking property was evaluated according to the following criteria.

[0172] A: The dielectric layer is not adhered to the PET film

[0173] B: The dielectric layer adheres to the PET film but can be peeled off

[0174] C: The dielectric layer adheres to the PET film and cannot be peeled off

[0175] <Transferability>

[0176] The release substrates with dielectric layers produced in Examples and Comparative Examples were cut into squares of 5 cm in width and 5 cm in length to prepare test pieces.

[0177] Prepare two test pieces, overlap each other with the dielectric layers facing each other, and heat at 40°C and 5 kg / cm 2 Press under pressure for 10 seconds.

[0178] Then, the release substrate of one of the test pieces was peeled off, and the peeling state (transferability) of the dielectric layer was visually confirmed. The transferability was evaluated based on the following criteria.

[0179] A: The dielectric layers remain bonded to each other and no dielectric layer remains on the surface of the release substrate after peeling.

[0180] B: The dielectric layers remain bonded to each other, but a portion of the dielectric layer remains on the surface of the release substrate after peeling.

[0181] C: The dielectric layers are not adhered to each other, and most of the dielectric layer remains on the surface of the release substrate

[0182] <Adhesion>

[0183] The release substrate with a dielectric layer manufactured in the examples and comparative examples was cut into a rectangle of 10 mm wide and 100 mm long as a test piece. A cellophane tape (cellophane tape defined in JIS Z1522) was pasted on the dielectric layer of the test piece. The cellophane tape was fixed in a flat state on the horizontal surface of the test bench, and one end of the release substrate was pulled at a tensile speed of 10 mm / min in a direction perpendicular to the cellophane tape surface to peel it off, and the stress at this time was measured. Three measurements were performed, and the average value was calculated and used as the peel strength, and evaluated according to the following benchmarks. The greater the peel strength, the better the adhesion between the dielectric layer and the release substrate.

[0184] A: Peel strength is 50N / m or more

[0185] B: Peel strength is 10 N / m or more and less than 50 N / m

[0186] C: Peel strength less than 10N / m

[0187] (Example 1)

[0188] <Preparation of Particulate Polymer Dispersion (Adhesive Composition)>

[0189] In a 5 MPa pressure-resistant container equipped with a stirrer, 92 parts of n-butyl acrylate (BA), 2 parts of acrylic acid (AA), and 6 parts of acrylonitrile (AN) as a monomer composition, 0.4 parts of sodium lauryl sulfate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of ammonium persulfate as a polymerization initiator were added. After thorough stirring, the temperature was raised to 80°C to initiate polymerization. When the polymerization conversion reached 96%, the reaction was terminated by cooling to obtain a mixture containing a granular polymer.

[0190] A 5% aqueous sodium hydroxide solution was added to the mixture containing the granular polymer to adjust the pH to 7. Unreacted monomers were then removed by distillation under reduced pressure while heating. The mixture was then cooled to 30°C or less to obtain a dispersion containing the desired granular polymer (the solvent being water). The solids concentration of the dispersion was 40%.

[0191] Using the obtained dispersion, the glass transition temperature of the particulate polymer, the volume average particle size of the particulate polymer, and the THF-insoluble content of the particulate polymer were measured.

[0192] <Preparation of Slurry Composition>

[0193] 100 parts of barium titanate ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with a volume average particle size (d50) of 0.1 μm as a dielectric material, 12.5 parts (5 parts in terms of solid content) of an aqueous solution of polyvinyl butyral (BL-2H manufactured by Sekisui Chemical Co., Ltd.) as a viscosity modifier, and 20 parts of water as a dispersion medium were stirred at 500 rpm for 20 hours along with 100 parts of zirconia beads (manufactured by NIKKATO Co., Ltd.) with a particle size of 0.1 mm as mixing beads using a bead mill ("RMB-01" manufactured by AIMEX Co., Ltd.). Subsequently, 20 parts of water were added and stirred at 500 rpm for 10 hours. The zirconia beads were filtered out to prepare a dispersion of barium titanate.

[0194] To 152.5 parts of the barium titanate dispersion (containing 100 parts of barium titanate) was added 12.5 parts of the above-prepared particulate polymer dispersion (containing 5 parts of particulate polymer), and the mixture was stirred at 1000 rpm for 3 minutes using an autorotating stirrer to prepare a slurry composition.

[0195] <Fabrication of Dielectric Layer>

[0196] The slurry composition obtained above was applied to a 100 mm wide x 100 mm long release-treated film (PET38AL-5, manufactured by Lintec) using a gravure coater to a dielectric layer thickness of approximately 1.0 μm after drying. The film was then dried at 100°C for 5 minutes in air to form a dielectric layer on the release substrate (ceramic green sheet method). The release substrate with the resulting dielectric layer was used to evaluate its anti-blocking properties, transferability, and adhesion. The results are shown in Table 1.

[0197] (Example 2)

[0198] In preparation of the dispersion of the particulate polymer, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a composition containing 64 parts of 2-ethylhexyl acrylate (2-EHA), 1 part of itaconic acid (IA), and 35 parts of styrene (St) was used as the monomer composition. The results are shown in Table 1.

[0199] (Comparative Example 1)

[0200] In the preparation of the slurry composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 25 parts (10 parts in terms of solid content) of an aqueous solution of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., BL-2H) was used instead of the dispersion of the particulate polymer as the binder composition. The results are shown in Table 1.

[0201] In Comparative Example 1, since no particulate polymer was used, the volume average particle size of the particulate polymer, the glass transition temperature of the particulate polymer, and the THF-insoluble content of the particulate polymer were not measured.

[0202] (Comparative Example 2)

[0203] Toluene was used as the solvent and dispersion medium in the preparation of the particulate polymer dispersion and the preparation of the slurry composition. Specifically, the particulate polymer dispersion and the slurry composition were prepared as follows. In addition, polyvinyl butyral (BL-2H, manufactured by Sekisui Chemical Co., Ltd.) was not used in the preparation of the slurry composition. Various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0204] <Preparation of Particulate Polymer Dispersion (Adhesive Composition)>

[0205] In a 5 MPa pressure-resistant container equipped with a stirrer, 92 parts of n-butyl acrylate (BA), 2 parts of acrylic acid (AA), and 6 parts of acrylonitrile (AN) as a monomer composition, 0.4 parts of sodium lauryl sulfate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of ammonium persulfate as a polymerization initiator were added. After thorough stirring, the temperature was raised to 80°C to initiate polymerization. When the polymerization conversion reached 96%, the reaction was terminated by cooling to obtain a mixture containing a granular polymer.

[0206] Toluene was added to the mixture containing the granular polymer, and the unreacted monomers and ion-exchanged water were removed by heating and distillation under reduced pressure to perform solvent replacement. The mixture was then cooled to below 30°C to obtain a dispersion containing the desired granular polymer (the solvent being toluene). The solids concentration of the dispersion was 40%.

[0207] <Preparation of Slurry Composition>

[0208] 100 parts of barium titanate ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with a volume average particle size (d50) of 0.1 μm as a dielectric material, 20 parts of toluene as a dispersion medium, and 100 parts of zirconia beads ("RMB-01" manufactured by NIKKATO Co., Ltd.) with a particle size of 0.1 mm as mixing beads were stirred at 500 rpm for 2 hours using a bead mill ("RMB-01" manufactured by AIMEX Co., Ltd.). Subsequently, 20 parts of toluene were added, and the mixture was stirred at 500 rpm for 1 hour. The zirconia beads were filtered out to prepare a dispersion of barium titanate.

[0209] To 140.0 parts of the barium titanate dispersion (containing 100 parts of barium titanate) was added 25 parts of the above-prepared dispersion of the particulate polymer (containing 10 parts of the particulate polymer), and the mixture was stirred at 1000 rpm for 3 minutes using an autorotating and orbiting stirrer to prepare a slurry composition.

[0210] [Table 1]

[0211]

[0212] As is apparent from Table 1, the use of the dispersion liquid (adhesive composition) of the particulate polymer of the Examples can impart excellent anti-blocking properties and transferability to the dielectric layer.

[0213] Industrial applicability

[0214] According to the present invention, it is possible to provide an adhesive composition for a dielectric layer that can impart excellent anti-blocking properties and transferability to a dielectric layer.

[0215] Furthermore, according to the present invention, a slurry composition for a dielectric layer capable of imparting excellent anti-blocking properties and transferability to a dielectric layer can be provided.

[0216] Furthermore, according to the present invention, there can be provided a dielectric layer obtained by drying a coating film formed from the above-mentioned slurry composition for a dielectric layer.

[0217] Furthermore, according to the present invention, it is possible to provide a capacitor formed using the above-mentioned dielectric layer.

[0218] Description of Reference Numerals

[0219] 10: Multilayer ceramic capacitor;

[0220] 11: dielectric;

[0221] 12: internal electrode;

[0222] 13: External electrode.

Claims

1. An adhesive composition for a dielectric layer, comprising a particulate polymer and water, wherein the particulate polymer contains a (meth)acrylic acid ester monomer unit.

2. The adhesive composition for a dielectric layer according to claim 1, wherein The glass transition temperature of the particulate polymer is -50°C or higher and 20°C or lower.

3. The adhesive composition for a dielectric layer according to claim 1, wherein The volume average particle size of the particulate polymer is 0.01 μm or more and 1.0 μm or less. 4 . A slurry composition for a dielectric layer, comprising the binder composition for a dielectric layer according to claim 1 , a dielectric material, and a solvent. 5 . A dielectric layer obtained by drying a coating film formed from the slurry composition for a dielectric layer according to claim 4 . 6 . A capacitor formed by using the dielectric layer according to claim 5 .

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