Binder composition for dielectric layer, slurry composition for dielectric layer, dielectric layer, and multilayer ceramic capacitor

Abstract

To provide a binder composition for a dielectric layer capable of imparting excellent crack resistance and laminatability to the dielectric layer, and excellent dispersion stability to a slurry composition for the dielectric layer.SOLUTION: The present invention provides a binder composition for a dielectric layer, the binder composition including a polymer containing an epoxy group-containing monomer unit and water.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a binder composition for a dielectric layer, a slurry composition for a dielectric layer, a dielectric layer, and a multilayer ceramic capacitor. [Background technology]

[0002] Multilayer ceramic capacitors are generally manufactured using dielectric layers such as ceramic green sheets. The dielectric layer can be obtained, for example, by first preparing a slurry composition containing a binder, a dielectric material, and a solvent, then applying the slurry composition to a release substrate and drying it. The obtained dielectric layers are then stacked, optionally subjected to a degreasing treatment (binder removal treatment), and sintered to obtain a multilayer ceramic capacitor.

[0003] In recent years, in order to impart excellent properties to multilayer ceramic capacitors, development has been progressing on slurry compositions used in the production of dielectric layers and binders contained in such slurry compositions. For example, Patent Document 1 proposes using a (meth)acrylate copolymer having a predetermined composition and a predetermined weight-average molecular weight as a binder for a slurry composition to obtain a slurry composition that leaves little binder residue during binder removal treatment and that can produce ceramic green sheets that have excellent smoothness and ceramic particle density after binder removal treatment. Furthermore, for example, Patent Document 2 proposes using a copolymer for a firing paste obtained by copolymerizing a monomer mixture containing two specific monomers as a binder resin for a firing paste composition in order to obtain a firing paste composition that has a moderate viscosity, excellent coatability, is free from the problem of stringiness, and has good firing properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6337628 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-59196 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in dielectric layers such as ceramic green sheets, further improvements are required in terms of suppressing cracks that may occur during the production of sintered bodies (hereinafter, this may be referred to as "crack resistance").

[0006] Furthermore, in the manufacture of multilayer ceramic capacitors, dielectric layers are typically stacked on top of each other and then pressed to obtain a laminate, and it is desirable that the dielectric layers in the obtained laminate are well bonded to each other (hereinafter, this may be referred to as "laminability").

[0007] Furthermore, since the slurry composition can be stored for a certain period of time (e.g., 7 days) after preparation, it is desirable that the slurry composition has little change in viscosity when comparing the viscosity after storage for a certain period of time with the viscosity immediately after preparation, and has excellent dispersion stability, in order to enable uniform application and suppress variations in the performance of the resulting multilayer ceramic capacitor.

[0008] However, conventional binders have room for improvement in terms of imparting excellent crack resistance and lamination properties to the dielectric layer and excellent dispersion stability to the slurry composition.

[0009] Therefore, an object of the present invention is to provide a binder composition for a dielectric layer that can impart excellent crack resistance and lamination properties to a dielectric layer and can also impart excellent dispersion stability to a slurry composition for a dielectric layer. Another object of the present invention is to provide a slurry composition for a dielectric layer that can impart excellent crack resistance and lamination properties to the dielectric layer and has excellent dispersion stability. Another object of the present invention is to provide a dielectric layer obtained by drying a coating film made of the above-mentioned slurry composition for a dielectric layer. Another object of the present invention is to provide a multilayer ceramic capacitor obtained by sintering a laminate in which the above-mentioned dielectric layers are stacked one on top of the other. [Means for solving the problem]

[0010] The present inventors have conducted extensive research with the aim of solving the above-mentioned problems, and have newly discovered that the above-mentioned problems can be solved by a binder composition for a dielectric layer that contains water and a polymer containing a monomer unit having a predetermined functional group, and have thus completed the present invention.

[0011] That is, the present invention aims to advantageously solve the above-mentioned problems, and [1] the present invention is a binder composition for a dielectric layer, which comprises a polymer containing an epoxy group-containing monomer unit and water.

[0012] [2] In the binder composition for a dielectric layer described in [1] above, the content of the epoxy group-containing monomer unit is preferably 0.1% by mass or more and 30% by mass or less, when the total amount of all repeating units contained in the polymer is 100% by mass. In this specification, the content ratio of various repeating units (monomer units) in the polymer is 1 It can be measured using nuclear magnetic resonance (NMR) techniques such as H-NMR.

[0013] [3] In the binder composition for a dielectric layer according to the above [1] or [2], the polymer preferably further contains a (meth)acrylic acid ester monomer unit. In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0014] [4] In the binder composition for a dielectric layer described in [3] above, the content of the (meth)acrylic acid ester monomer unit is preferably 60% by mass or more and 95% by mass or less, when the total repeating units contained in the polymer is 100% by mass.

[0015] [5] In the binder composition for a dielectric layer according to any one of the above [1] to [4], the polymer is preferably water-insoluble. In this specification, a 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 mass % or more.

[0016] [6] In the binder composition for a dielectric layer according to any one of the above [1] to [5], the polymer is preferably in the form of particles, and the volume average particle diameter of the polymer is preferably 0.01 μm or more and 0.5 μm or less. In this specification, the volume average particle size of the polymer can be measured according to the method described in the Examples.

[0017] [7] In the binder composition for a dielectric layer according to any one of the above [1] to [6], the glass transition temperature of the polymer is preferably −60° C. or higher and 0° C. or lower. In this specification, the glass transition temperature of a polymer can be measured according to the method described in the examples.

[0018] The present invention also aims to advantageously solve the above-mentioned problems, and [8] the present invention is a slurry composition for a dielectric layer, comprising the binder composition for a dielectric layer according to any one of [1] to [7] above, and a dielectric material.

[0019] The present invention also aims to advantageously solve the above problems, and [9] the present invention is a dielectric layer formed by drying a coating film made of the slurry composition for a dielectric layer according to [8] above.

[0020] Another object of the present invention is to advantageously solve the above problems, and

[10] the present invention is a multilayer ceramic capacitor obtained by sintering a laminate in which the dielectric layers according to [9] above are stacked. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a binder composition for a dielectric layer that can impart excellent crack resistance and lamination properties to a dielectric layer and also excellent dispersion stability to a slurry composition for a dielectric layer. Furthermore, according to the present invention, it is possible to provide a slurry composition for a dielectric layer that can impart excellent crack resistance and lamination properties to the dielectric layer and has excellent dispersion stability. Furthermore, according to the present invention, it is possible to provide a dielectric layer obtained by drying a coating film made of the above-mentioned slurry composition for a dielectric layer. Furthermore, according to the present invention, it is possible to provide a multilayer ceramic capacitor obtained by sintering a laminate in which the above-mentioned dielectric layers are stacked. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic cross-sectional view showing an example of a multilayer ceramic capacitor of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described in detail. Here, the binder composition for a dielectric layer of the present invention (hereinafter sometimes simply referred to as the "binder composition") can be used to prepare a slurry composition for a dielectric layer of the present invention (hereinafter sometimes simply referred to as the "slurry composition"). The slurry composition of the present invention can be used to form a dielectric layer used in the manufacture of a multilayer ceramic capacitor or the like. Furthermore, the dielectric layer of the present invention is formed by drying a coating film made of the slurry composition of the present invention. Furthermore, the multilayer ceramic capacitor of the present invention is formed by stacking dielectric layers formed using the slurry composition of the present invention and sintering the resulting laminate.

[0024] (Binder composition for dielectric layer) The binder composition for a dielectric layer of the present invention contains a polymer containing an epoxy group-containing monomer unit and water, and may optionally further contain components other than the polymer and the solvent (hereinafter, sometimes referred to as "other components"). The binder composition as described above can impart excellent crack resistance and lamination properties to the dielectric layer, and can also impart excellent dispersion stability to the slurry composition for the dielectric layer. The reasons for this are presumed to be as follows.

[0025] First, it is presumed that in the slurry composition, the epoxy groups of the polymer interact with the dielectric material described below, allowing the polymer to coat the dielectric material well, thereby imparting excellent dispersion stability to the slurry composition for the dielectric layer. Furthermore, it is presumed that in the dielectric layer, the epoxy groups of the polymer can form strong bonds with the surface of the dielectric material, thereby imparting excellent lamination properties to the dielectric layer. Furthermore, when the dielectric layer is sintered, the dielectric materials can be well bonded together via the polymer having epoxy groups, which is thought to impart excellent crack resistance to the dielectric layer.

[0026] In this specification, the binder composition generally does not contain a dielectric material, which will be described later.

[0027] <Polymer> The polymer contained in the binder composition of the present invention is a component that can function as a binding material, and contains an epoxy group-containing monomer unit. The epoxy group of the epoxy group-containing monomer unit may be present in a ring-opened state, for example, in the binder composition in the form of a ring-opened diol type.

[0028] The polymer contained in the binder composition of the present invention may optionally further contain (meth)acrylic acid ester monomer units, cyano group-containing monomer units, and hydrophilic group-containing monomer units. Here, the polymer preferably further contains (meth)acrylic acid ester monomer units in addition to epoxy group-containing monomer units, because this can improve the dispersion stability of the resulting slurry composition and the crack resistance of the resulting dielectric layer. The polymer may optionally further contain monomer units other than the epoxy group-containing monomer units, (meth)acrylic acid ester monomer units, cyano group-containing monomer units, and hydrophilic group-containing monomer units (hereinafter, these may be referred to as "other monomer units").

[0029] <<Epoxy group-containing monomer unit>> The epoxy group-containing monomer unit is a monomer unit that can be formed by an epoxy group-containing monomer. The epoxy group-containing monomer includes a monomer that contains a carbon-carbon double bond and an epoxy group. Examples of the monomer containing a carbon-carbon double bond and an epoxy group include unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, and o-allylphenyl glycidyl ether; diene or polyene monoepoxides such as butadiene monoepoxide, chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, and 1,2-epoxy-5,9-cyclododecadiene; and 3,4-epoxy-1- Examples of the epoxy group-containing monomer include alkenyl epoxides such as butene, 1,2-epoxy-5-hexene, and 1,2-epoxy-9-decene; glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl 4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl 4-methyl-3-pentenoate, glycidyl ester of 3-cyclohexenecarboxylic acid, and glycidyl ester of 4-methyl-3-cyclohexenecarboxylic acid; and the like. One type of epoxy group-containing monomer may be used alone, or two or more types may be used in combination in any ratio. Among these, the epoxy group-containing monomer is preferably an unsaturated glycidyl ether or a glycidyl ester of an unsaturated carboxylic acid, i.e., the epoxy group-containing monomer unit is preferably at least one of an unsaturated glycidyl ether unit and a glycidyl ester unit of an unsaturated carboxylic acid. Furthermore, the unsaturated glycidyl ether is preferably allyl glycidyl ether, and the glycidyl ester of unsaturated carboxylic acid is preferably glycidyl methacrylate. That is, the unsaturated glycidyl ether unit is preferably an allyl glycidyl ether unit, and the glycidyl ester of unsaturated carboxylic acid unit is preferably a glycidyl methacrylate unit.

[0030] The content of the epoxy group-containing monomer units in the polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and even more preferably 8% by mass or more, and is preferably 30% by mass or less, and more preferably 20% by mass or less, when all repeating units (all monomer units) contained in the polymer are taken as 100% by mass. When the content of the epoxy group-containing monomer unit in the polymer is equal to or greater than the above lower limit, the lamination property and crack resistance of the resulting dielectric layer can be effectively improved. On the other hand, if the content of the epoxy group-containing monomer units in the polymer is equal to or less than the above upper limit, the dispersion stability of the resulting slurry composition can be effectively improved.

[0031] <<(Meth)acrylic acid ester monomer unit>> The (meth)acrylic acid ester monomer unit is a monomer unit that can be formed by a (meth)acrylic acid ester monomer. Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and octyl (meth)acrylate such as 2-ethylhexyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, as the (meth)acrylic acid ester monomer, from the viewpoint of the dispersion stability of the resulting slurry composition and the crack resistance of the resulting dielectric layer, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and n-butyl acrylate is more preferred. In other words, it is preferred that the (meth)acrylic acid ester monomer is at least one monomer unit selected from the group consisting of an ethyl (meth)acrylate unit, an n-butyl (meth)acrylate unit, and a 2-ethylhexyl (meth)acrylate unit, and n-butyl (meth)acrylate unit is more preferred. In this specification, the term "(meth)acrylate" means acrylate and / or methacrylate.

[0032] The content of (meth)acrylic acid ester monomer units in the polymer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, when all repeating units (all monomer units) contained in the polymer are taken as 100% by mass. When the content of the (meth)acrylic acid ester monomer unit in the polymer is equal to or more than the above lower limit, the dispersion stability of the resulting slurry composition can be improved. On the other hand, if the content of the (meth)acrylic acid ester monomer unit in the polymer is equal to or less than the upper limit, the lamination property and crack resistance of the resulting dielectric layer can be improved.

[0033] <<Cyano group-containing monomer unit>> The cyano group-containing monomer unit is a monomer unit that can be formed by a cyano group-containing monomer. Examples of the cyano group-containing monomer include acrylonitrile; methacrylonitrile, α-alkylacrylonitrile such as α-ethylacrylonitrile; and the like. These may be used alone or in combination of two or more in any ratio. Among these, the cyano group-containing monomer is preferably acrylonitrile or methacrylonitrile, more preferably acrylonitrile. That is, the cyano group-containing monomer unit is preferably at least one of an acrylonitrile unit and a methacrylonitrile unit, more preferably an acrylonitrile unit.

[0034] The content of the cyano group-containing monomer units in the polymer is preferably 1% by mass or more, more preferably 3% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, when all repeating units (all monomer units) contained in the polymer are taken as 100% by mass. When the content of the cyano group-containing monomer unit in the polymer is equal to or higher than the above lower limit, the strength of the polymer can be improved. On the other hand, if the content of the cyano group-containing monomer unit in the polymer is not more than the above upper limit, the drying speed of the resulting slurry composition is improved, and as a result, the productivity of the dielectric layer and the multilayer ceramic capacitor can be improved.

[0035] <<Hydrophilic group-containing monomer unit>> The hydrophilic group-containing monomer unit is a monomer unit that can be formed from a hydrophilic group-containing monomer. Examples of the hydrophilic group-containing monomer unit include an acid group-containing monomer unit, a hydroxyl group-containing monomer unit, and an amide group-containing monomer unit. Among these, the acid group-containing monomer unit is preferred.

[0036] -Acid group-containing monomer unit- The acid group-containing monomer unit is a monomer unit that can be formed by an acid group-containing monomer, such as a carboxylic acid group-containing monomer, a sulfonic acid group-containing monomer, or a phosphoric acid group-containing monomer.

[0037] Examples of the carboxylic acid group-containing monomer include monocarboxylic acids and their derivatives, dicarboxylic acids and their acid anhydrides and their derivatives. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid. Examples of the monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, and α-chloro-β-E-methoxyacrylic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, and maleic acid monoesters such as butyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleates. Examples of the acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, and citraconic anhydride. Furthermore, as the carboxylic acid group-containing monomer, an acid anhydride that generates a carboxylic acid group upon hydrolysis can also be used. Furthermore, as the carboxylic acid group-containing monomer, ethylenically unsaturated polycarboxylic acids such as butenetricarboxylic acid, and partial esters of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate and mono-2-hydroxypropyl maleate can also be used.

[0038] Examples of sulfonic acid group-containing monomers include vinyl sulfonic acid (ethylene sulfonic acid), methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, and 3-allyloxy-2-hydroxypropane sulfonic acid. In this specification, "(meth)allyl" means allyl and / or methallyl.

[0039] Examples of the phosphate group-containing monomer include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, vinylphosphonic acid, and dimethyl vinylphosphonate. In this specification, the term "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0040] Here, the acid group-containing monomer is preferably a carboxylic acid group-containing monomer, more preferably acrylic acid or methacrylic acid, and even more preferably methacrylic acid. That is, the acid group-containing monomer unit is preferably a carboxylic acid group-containing monomer unit, more preferably at least one of an acrylic acid unit and a methacrylic acid unit, and even more preferably a methacrylic acid unit.

[0041] -Amide group-containing monomer unit- Examples of the amide group-containing monomer capable of forming the amide group-containing monomer unit include acrylamide and methacrylamide.

[0042] -Hydroxyl group-containing monomer unit- Examples of hydroxyl group-containing monomers that can form hydroxyl group-containing monomer units include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-butene-1-ol, and 5-hexene-1-ol; alkanol esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate (2-hydroxyethyl methacrylate), 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, and di-2-hydroxypropyl itaconate; and esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, di-4-hydroxybutyl maleate, and di-2-hydroxypropyl itaconate; 1 -COO-(C q H 2q O) p -H (wherein p is an integer of 2 to 9, q is an integer of 2 to 4, R 1represents hydrogen or a methyl group) and (meth)acrylic acid esters; mono(meth)acrylic acid esters of dihydroxy esters of dicarboxylic acids such as 2-hydroxyethyl-2'-(meth)acryloyloxyphthalate and 2-hydroxyethyl-2'-(meth)acryloyloxysuccinate; vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; mono(meth)allyl alkylene glycols such as (meth)allyl-2-hydroxyethyl ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl-3-hydroxybutyl ether, (meth)allyl-4-hydroxybutyl ether, and (meth)allyl-6-hydroxyhexyl ether. ethers; polyoxyalkylene glycol mono(meth)allyl ethers such as diethylene glycol mono(meth)allyl ether and dipropylene glycol mono(meth)allyl ether; mono(meth)allyl ethers of halogen- and hydroxy-substituted (poly)alkylene glycols such as glycerin mono(meth)allyl ether, (meth)allyl-2-chloro-3-hydroxypropyl ether and (meth)allyl-2-hydroxy-3-chloropropyl ether; mono(meth)allyl ethers of polyhydric phenols such as eugenol and isoeugenol and halogen-substituted products thereof; (meth)allyl thioethers of alkylene glycols such as (meth)allyl-2-hydroxyethyl thioether and (meth)allyl-2-hydroxypropyl thioether; 2-hydroxyethyl(meth)acrylamide, N-methylolacrylamide; etc. These may be used alone or in combination of two or more.

[0043] The content of the hydrophilic group-containing monomer unit in the polymer is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, when all repeating units (all monomer units) contained in the polymer are taken as 100% by mass. When the content of the hydrophilic group-containing monomer unit is equal to or higher than the above lower limit, the dispersion stability of the resulting slurry composition can be improved. On the other hand, if the content of the hydrophilic group-containing monomer unit is equal to or less than the above upper limit, the blocking resistance of the resulting dielectric layer can be improved.

[0044] <<Total content of (meth)acrylic acid ester monomer units, cyano group-containing monomer units, and hydrophilic group-containing monomer units>> The total content of the (meth)acrylic acid ester monomer units, the cyano group-containing monomer units, and the hydrophilic group-containing monomer units in the polymer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and is preferably 99.9% by mass or less, more preferably 90% by mass or less, even more preferably 95% by mass or less, and even more preferably 92% by mass or less, when all repeating units (all monomer units) contained in the polymer are taken as 100% by mass. When the total content of the monomer units in the polymer is equal to or greater than the lower limit, the dispersion stability of the resulting slurry composition can be effectively improved. On the other hand, if the total content of the above monomer units in the polymer is equal to or less than the above upper limit, the lamination property and crack resistance of the resulting dielectric layer can be effectively improved.

[0045] <<Other monomer units>> The other monomer unit is a monomer unit that can be formed by another monomer. The other monomer is not particularly limited as long as it is a monomer that can copolymerize with the monomer that can form the above-mentioned polymer. Examples of the other monomer include olefins such as ethylene and propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; and vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether. These other monomers may be used alone or in combination of two or more.

[0046] The content of other monomer units in the polymer is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass, i.e., the polymer does not contain any other monomer units, when all repeating units (all monomer units and all structural units) contained in the water-soluble polymer are taken as 100% by mass.

[0047] <<Polymer properties>> The polymer contained in the binder composition of the present invention is preferably water-insoluble. If the polymer is water-insoluble, the dispersion stability of the resulting slurry composition can be improved. Furthermore, the lamination property and crack resistance of the resulting dielectric layer can be improved.

[0048] The polymer contained in the binder composition of the present invention is preferably in a particulate form (a so-called particulate polymer). If the polymer is in a particulate form, the dispersion stability of the resulting slurry composition can be improved. Furthermore, the lamination property and crack resistance of the resulting dielectric layer can be improved.

[0049] When the polymer in the binder composition of the present invention is in a particulate form, the volume average particle diameter of the polymer is preferably 0.01 μm or more, more preferably 0.05 μm or more, and is preferably 0.5 μm or less, more preferably 0.3 μm or less. When the volume average particle size of the polymer is equal to or greater than the above lower limit, the dispersion stability of the resulting slurry composition can be effectively improved. On the other hand, if the volume average particle size of the polymer is equal to or less than the above upper limit, the lamination property and crack resistance of the resulting dielectric layer can be effectively improved.

[0050] The glass transition temperature of the polymer is preferably −60° C. or higher, more preferably −55° C. or higher, and even more preferably −45° C. or higher, and is preferably 0° C. or lower, more preferably −5° C. or lower, and even more preferably −1° C. or lower. When the glass transition temperature of the polymer is equal to or higher than the lower limit, the dispersion stability of the resulting slurry composition can be improved. On the other hand, if the glass transition temperature of the polymer is equal to or lower than the upper limit, the crack resistance of the resulting dielectric layer can be improved.

[0051] <<Polymerization method>> The method for polymerizing the polymer is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization may be used. The polymerization reaction may be addition polymerization such as ionic polymerization, radical polymerization, or living radical polymerization. Common polymerization solvents and additives such as emulsifiers, dispersants, polymerization initiators, chain transfer agents, and pH adjusters may be used in the polymerization, and the amounts used may be the amounts commonly used.

[0052] When water is used as the polymerization solvent, the pH of the polymerization solvent is preferably in the range from weakly acidic to alkaline (for example, pH 6 or higher and 10 or lower). If the pH of the polymerization solvent is in the range from weakly acidic to alkaline, unintended reaction of the epoxy groups can be effectively prevented. The pH of the polymerization solvent can be adjusted using a pH adjuster, etc. As the pH adjuster, for example, aqueous ammonia can be used.

[0053] The polymerization temperature is preferably 35°C or higher, more preferably 45°C or higher, and is preferably 65°C or lower, preferably 55°C or lower, and more preferably 50°C or lower. When the polymerization temperature is equal to or higher than the above lower limit, the polymerization can be carried out efficiently. On the other hand, if the polymerization temperature is equal to or lower than the above upper limit, unintended reaction of the epoxy groups can be effectively suppressed.

[0054] <Solvent> The binder composition of the present invention contains water as a solvent. Note that the binder composition of the present invention may contain a solvent other than water as long as the object of the present invention is not impaired. However, from the viewpoints of reducing the environmental load and safety, it is preferable that the binder composition of the present invention contains only water as a solvent.

[0055] <Other ingredients> The binder composition of the present invention may optionally contain other components, such as the additives used in polymerizing the polymer.

[0056] <Solid content concentration of binder composition for dielectric layer> The solid content concentration of the binder composition is preferably 20% by mass or more, more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less.

[0057] <Method for preparing binder composition for dielectric layer> The binder composition of the present invention can be prepared by mixing the above-mentioned polymer, water, and any other components by a known method. Specifically, the binder composition can be prepared by mixing the above-mentioned components using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, a Filmix, or a planetary / revolution mixer.

[0058] (Slurry composition for dielectric layer) The slurry composition for a dielectric layer of the present invention contains the binder composition of the present invention described above and a dielectric material, and may optionally further contain a water-soluble polymer and other components (hereinafter, may be referred to as "other components"). That is, the slurry composition of the present invention contains the polymer described above (a polymer containing epoxy group-containing monomer units), water, and a dielectric material, and may optionally further contain a water-soluble polymer and other components. The slurry composition of the present invention contains the binder composition of the present invention, and therefore can impart excellent crack resistance and lamination properties to the dielectric layer, and also has excellent dispersion stability.

[0059] <Dielectric materials> The dielectric material is not particularly limited as long as it is a material having dielectric properties, but it is preferable to use a ceramic material. Examples of ceramic materials include zirconia, aluminum silicate, titanium oxide, zinc oxide, barium titanate, calcium zirconate, calcium titanate, strontium titanate, magnesia, sialon, spinemullite, silicon carbide, silicon nitride, and aluminum nitride. These ceramic materials may be used alone or in combination of two or more.

[0060] Here, the ceramic material is preferably a ceramic material having a perovskite structure represented by the general formula ABO3 as the main phase. Examples of the ceramic material include barium titanate (BaTiO3), calcium zirconate (CaZrO3), calcium titanate (CaTiO3), strontium titanate (SrTiO3), and BaTiO3, which form the perovskite structure. 1-x-y Ca x Sr y Ti 1-z Zr z O3 (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 the main phase.

[0061] The volume average particle size of the dielectric material is preferably 0.01 μm or more, more preferably 0.02 μm or more, even more preferably 0.05 μm or more, even more preferably 0.08 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.5 μm or less, even more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. When the volume average particle size of the dielectric material is within the above range, the 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. In this specification, the volume average particle size of a dielectric material means the particle size at which the cumulative volume calculated from the smallest diameter side is 50% in the particle size distribution (volume basis) obtained by measurement using a laser diffraction method.

[0062] The content of the dielectric material in the slurry composition is preferably 40% by mass or more, more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, when all components in the slurry composition (including the solvent) are taken as 100% by mass.

[0063] <Water-soluble polymer> The water-soluble polymer that can be optionally contained in the slurry composition of the present invention is a component that can function as a viscosity modifier and a binder, and typically contains a hydrophilic group-containing structural unit. The water-soluble polymer may optionally contain a (meth)acrylic acid ester monomer unit in addition to the hydrophilic group-containing structural unit. The water-soluble polymer may further contain a monomer unit (hereinafter sometimes referred to as "other monomer unit") other than the hydrophilic group-containing structural unit and the (meth)acrylic acid ester monomer unit.

[0064] <<Structural units having hydrophilic groups>> The structural unit having a hydrophilic group (hereinafter, sometimes referred to as a "hydrophilic group-containing structural unit") may be a structural unit that can be formed from a hydrophilic group-containing monomer, or may be a structural unit obtained by obtaining a water-soluble polymer using a monomer composition containing a monomer having a predetermined functional group, and then modifying or converting the functional group into a hydrophilic group. Examples of the hydrophilic group-containing monomer include those described in the section "Hydrophilic Group-Containing Monomer Unit" in the above-mentioned "Binder Composition for Dielectric Layer." These may be used alone or in combination of two or more.

[0065] Here, the structure of the structural unit having a hydroxyl group as a hydrophilic group (hereinafter, sometimes referred to as a "hydroxyl group-containing structural unit") is not particularly limited as long as it is a repeating unit having a hydroxyl group. The method for introducing the hydroxyl group-containing structural unit into the water-soluble polymer may be, for example, the following method (1) or (2): (1) A method for preparing a water-soluble polymer containing a hydroxyl group-containing structural unit from a monomer composition containing a hydroxyl group-containing monomer. (2) A method for preparing a water-soluble polymer containing vinyl alcohol units and, optionally, vinyl carboxylic acid ester monomer units, by preparing a polymer from a monomer composition containing a vinyl carboxylic acid ester monomer represented by the general formula: R-CO-O-CH=CH2 (wherein R is any structure, but is preferably an alkyl group having 1 to 19 carbon atoms), and saponifying the polymer to convert all or part of the "R-CO-O-" of the vinyl carboxylic acid ester monomer units into hydroxyl groups. The hydroxyl group-containing monomer used in the above method (1) may be the same as those described in the section "Hydroxyl group-containing monomer unit" in the above "Binder composition for dielectric layer."

[0066] Examples of the vinyl carboxylate monomer used in the above method (2) include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, and vinyl stearate. These can be used alone or in combination of two or more. Among these, vinyl acetate is preferred. Examples of the water-soluble polymer obtained by the above method (2) include polyvinyl alcohol, etc. These may be used alone or in combination of two or more.

[0067] <<(Meth)acrylic acid ester monomer unit>> The (meth)acrylic acid ester monomer unit that can be optionally contained in the water-soluble polymer is a monomer unit that can be formed from a (meth)acrylic acid ester monomer. Examples of the (meth)acrylic acid ester monomer that can be used to prepare the water-soluble polymer include the same monomers as those explained in the section "(meth)acrylic acid ester monomer unit" in the above-mentioned "Binder composition for dielectric layer." These may be used alone or in combination of two or more. Among these, ethyl (meth)acrylate and n-butyl (meth)acrylate are preferred. That is, the (meth)acrylic acid ester monomer unit is preferably at least one of an ethyl (meth)acrylate unit and an n-butyl (meth)acrylate unit. It is particularly preferable that the water-soluble polymer contains both ethyl (meth)acrylate units and n-butyl (meth)acrylate units.

[0068] The content of (meth)acrylic acid ester monomer units in the water-soluble polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, when all repeating units (all monomer units and all structural units) contained in the water-soluble polymer are taken as 100% by mass.

[0069] The content (solid content) of the water-soluble polymer is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the dielectric material in the slurry composition.

[0070] <Other ingredients> Other components that can be contained in the slurry composition of the present invention include the same as those explained in the section "Other Components" of the "Binder Composition for Dielectric Layer" above.

[0071] <Content of polymer containing epoxy group-containing monomer unit> The content (solid content) of the above-mentioned polymer (polymer containing epoxy group-containing monomer units) in the slurry composition is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the dielectric material in the slurry composition.

[0072] <Solid Content Concentration of Slurry Composition for Dielectric Layer> The solid content concentration of the slurry composition is preferably 20% by mass or more, more preferably 25% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less.

[0073] <Method for preparing a slurry composition for a dielectric layer> The above-mentioned slurry composition can be prepared by mixing the above-mentioned components by a known mixing method. Examples of mixers used for the preparation include those listed in the above "Method for preparing a binder composition for a dielectric layer."

[0074] (dielectric layer) The dielectric layer of the present invention is formed by drying a coating film made from the above-described slurry composition of the present invention. The dielectric layer of the present invention is usually a dried film obtained by partially or completely removing the solvent from a coating film made from the above-described slurry composition. That is, the dielectric layer of the present invention contains the above-described dielectric material and a polymer (a polymer containing an epoxy group-containing monomer unit), and may optionally contain a water-soluble polymer, water, and other components. The dielectric layer of the present invention is obtained by drying a coating film made of the slurry composition of the present invention, which has excellent dispersion stability, and therefore has excellent film thickness uniformity.Furthermore, the dielectric layer of the present invention is obtained by drying a coating film made of the slurry composition of the present invention, which can impart excellent crack resistance and lamination properties to the dielectric layer, and therefore has excellent crack resistance and lamination properties.

[0075] The content of the dielectric material in the dielectric layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, and is preferably 98% by mass or less, and more preferably 95% by mass or less, when all components in the dielectric layer are taken as 100% by mass.

[0076] The content of the polymer (polymer containing an epoxy group-containing monomer unit) in the dielectric layer is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the dielectric material in the dielectric layer.

[0077] The content of any water-soluble polymer in the dielectric layer is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the dielectric material in the dielectric layer.

[0078] The thickness of the dielectric layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less.

[0079] The dielectric layer of the present invention may have a conductor layer formed thereon. The conductor layer can be formed by various printing methods such as screen printing, gravure printing, stamp printing, inkjet printing, and offset printing using a pattern formed by these methods, or by vacuum deposition for forming a metal deposition film. When forming the conductor layer by printing, a conductive paste can be used. The conductive paste can be prepared by a conventionally known method, for example, by mixing a polyvinyl acetal resin with a conductive powder such as a metal, a dispersant, a plasticizer, a solvent, and the like.

[0080] <Method for producing dielectric layer> The dielectric layer can be produced by applying the slurry composition of the present invention to a release substrate and drying the resulting coating film.

[0081] Here, the release substrate used in producing the dielectric layer is preferably made of a flexible resin. By using a release substrate made of a flexible resin, the release substrate (laminated film) on which the dielectric layer is formed, obtained by applying the slurry composition to the release substrate and drying it, can be stored in a rolled state and supplied as needed. The release substrate is not particularly limited, and examples thereof include substrates containing polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, and other resins.

[0082] The release substrate is preferably subjected to a surface treatment to improve 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 treatments using a release agent such as a silicone-based release agent, a fluorine-based release agent, or a wax-based release agent.

[0083] The thickness of the release substrate is not particularly limited, but is usually 20 μm or more and 100 μm or less.

[0084] The method for applying the slurry composition to the release substrate is not particularly limited, and examples thereof include known application methods using an applicator or various roll coaters such as a gravure coater and a comma coater (registered trademark).

[0085] The method for drying the coating film formed on the release substrate is not particularly limited, and for example, a known drying method using a hot air dryer can be mentioned. The drying conditions can be appropriately set depending on the content of the solvent in the coating film, the thickness of the coating film, etc., but the drying temperature is usually 80°C or higher and 150°C or lower, and the drying time is usually 3 minutes or higher and 60 minutes or lower.

[0086] When the dielectric layer of the present invention is used in the production of a multilayer ceramic capacitor or the like, a plurality of dielectric layers may be superimposed on one another and then thermocompression bonded. However, the dielectric layer may be peeled off from the release substrate either before or after the superposition and thermocompression bonding of the dielectric layers.

[0087] (multilayer ceramic capacitors) The multilayer ceramic capacitor of the present invention is a sintered product obtained by sintering a laminate in which the dielectric layers of the present invention described above are stacked. The multilayer ceramic capacitor of the present invention is obtained by sintering a laminate in which the dielectric layers of the present invention, which have excellent film thickness uniformity, are stacked, and therefore performance variations are suppressed. Furthermore, the multilayer ceramic capacitor of the present invention is obtained by sintering a laminate in which the dielectric layers of the present invention, which have excellent crack resistance and stackability, are stacked, and therefore has excellent performance. An example of the multilayer ceramic capacitor of the present invention will be described below with reference to FIG. 1, but the multilayer ceramic capacitor of the present invention is not limited to this.

[0088] FIG. 1 is a schematic cross-sectional view showing an example of a multilayer ceramic capacitor according to the present invention. The multilayer ceramic capacitor 10 shown in FIG. 1 includes layered dielectrics 11 and layered internal electrodes 12 that are alternately stacked. A pair of external electrodes 13 is provided on the outer sides of the dielectrics 11 and the internal electrodes 12. One of the pair of internal electrodes 12 that are adjacent to each other along the stacking direction, sandwiching the dielectric 11 therebetween, is electrically connected to one of the pair of external electrodes 13 within the multilayer ceramic capacitor 10. The other of the pair of internal electrodes 12 that are adjacent to each other along the stacking direction, sandwiching the dielectric 11 therebetween, is electrically connected to the other of the pair of external electrodes 13 within the multilayer ceramic capacitor 10. This results in a structure in which multiple capacitor elements are electrically connected in parallel between the pair of external electrodes 13. Note that the interface between the dielectric layers of the present invention that may be formed when the dielectric layers are stacked is not shown in FIG. 1 because it may disappear when the dielectric layers are integrated by sintering.

[0089] The multilayer ceramic capacitor is not particularly limited and can be produced by a conventionally known method. For example, the multilayer ceramic capacitor can be produced by stacking a plurality of dielectric layers of the present invention, each having a conductive layer that can serve as an internal electrode, so that the dielectric layers and the conductive layers alternate, heat-pressing the stack to form a laminate, thermally decomposing and removing binder components (e.g., a polymer containing an epoxy group-containing monomer unit, a water-soluble polymer, etc.) contained in the laminate (degreasing treatment), sintering the stack, and then forming external electrodes on the end faces of the sintered ceramic product obtained by sintering.

[0090] The degreasing treatment is usually carried out in a nitrogen atmosphere at a temperature of 300° C. to 500° C. The degreasing treatment time is usually 1 hour to 5 hours. The binder content of the laminate after degreasing is usually 50 ppm or less.

[0091] The degreasing process is usually carried out under an oxygen partial pressure of 10 -9 ~10 -12The sintering is carried out in a reducing atmosphere such as H2-N2-H2O gas at 1000° C. to 1500° C. The sintering time for the laminate is usually 1 hour to 30 hours.

[0092] The external electrodes can be formed by applying an external electrode material to the end faces of the sintered ceramic body and then baking it, thereby obtaining, for example, the multilayer ceramic capacitor shown in Figure 1. Examples of materials for the external electrodes include Cu paste containing glass frit. Baking is usually performed in a nitrogen atmosphere at a temperature of 500°C to 1500°C. The surfaces of the external electrodes can also be plated with Ni, Sn, or the like. [Example]

[0093] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. Furthermore, in a polymer produced by polymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer usually coincides with the ratio (feed ratio) of that monomer to all the monomers used in the polymerization of the polymer, unless otherwise specified. The volume average particle size of the polymer, the glass transition temperature of the polymer, the dispersion stability, the lamination property, and the crack resistance were measured and evaluated by the following procedures.

[0094] <Method for measuring the glass transition temperature of a polymer> Aqueous dispersions containing the polymers of the Examples and Comparative Examples were dried for 3 days in an environment of 50% humidity and 25°C to obtain a film with a thickness of 1.0 mm. This film was then dried for 10 hours in a vacuum dryer at 60°C. The glass transition temperature (°C) of the dried film was then measured using a differential scanning calorimeter (DSC6220, manufactured by SII NanoTechnology Inc.) in accordance with JIS K7121 at a measurement temperature of -100°C to 180°C and a heating rate of 5°C / min.

[0095] <Method for measuring volume average particle size of polymer> The volume-average particle size of the polymer (particulate) in the examples and comparative examples was measured by laser diffraction. Specifically, an aqueous dispersion containing the prepared polymer (adjusted to a solids concentration of 0.1%) was used as a sample. The particle size distribution (volume basis) measured using a laser diffraction particle size distribution analyzer (manufactured by Beckman Coulter, Inc., product name "LS-230") was used. The particle size D50, at which the cumulative volume calculated from the smallest diameter reached 50%, was defined as the volume-average particle size.

[0096] <Dispersion stability> The viscosity η0 of the slurry compositions produced in the examples and comparative examples was measured at 25°C and 60 rpm using a Brookfield viscometer. The slurry compositions were then allowed to stand at 25°C for 7 days, and the viscosity η1 was measured again in the same manner as above. The viscosity change rate α was calculated using the measured viscosities η0 and η1 according to the following formula (1). Viscosity change rate α(%)=(η1 / η0)×100 (1) The dispersion stability was evaluated according to the following criteria: The viscosity change rate α is 100% or more, and the closer the viscosity change rate α is to 100%, the less the viscosity of the slurry composition is likely to change over time, indicating excellent dispersion stability. A: Viscosity change rate α is 100% or more but less than 150% B: Viscosity change rate α is 150% or more but less than 200% C: Viscosity change rate α is 200% or more

[0097] <Stackability> The release substrate with the dielectric layer prepared in the examples and comparative examples was cut into a square with a width of 5 cm and a length of 5 cm, and the release substrate was peeled off to prepare a test piece. Two such test pieces were prepared, stacked on top of each other, and then heated at 80°C and 5 kg / cm 2 The laminated dielectric layers were then cut with a cutter, and the cross section of the laminated dielectric layers was visually inspected and evaluated according to the following criteria. A: The dielectric layers are bonded together and no powder falls off at the cut surface. B: The dielectric layers are bonded together, but powder is falling off at the cut surface. C: The dielectric layers are not bonded together, and powder is falling off the cut surface.

[0098] <Crack resistance> The release substrate with the dielectric layer prepared in the examples and comparative examples was cut into a square with a width of 5 cm and a length of 5 cm, and the release substrate was peeled off to prepare a test piece. Two such test pieces were prepared, stacked on top of each other, and then heated at 80°C and 5 kg / cm 2 The laminate was pressed for 60 seconds under a pressure of 1000°C, and then fired at 1000°C for 5 hours and at 1200°C for 5 hours. The dielectric layer was visually inspected and the crack resistance was evaluated according to the following criteria. A: No cracks at both 1000℃ and 1200℃ B: No cracks occurred at 1000℃, but cracks occurred at 1200℃ C: Cracks occurred at both 1000℃ and 1200℃

[0099] Example 1 <Preparation of aqueous dispersion of polymer (binder composition)> In a 5 MPa pressure vessel A equipped with a stirrer, 20 parts of 10% aqueous ammonia as a pH adjuster, 54 parts of ion-exchanged water, 0.2 parts of sodium dodecyl diphenyl ether sulfonate as an emulsifier, 1 part of ammonium persulfate as a polymerization initiator, and 9.7 parts of ion-exchanged water were added, heated to 50 ° C., and stirred for 30 minutes. Next, in a separate 5 MPa pressure vessel B equipped with a stirrer, 82 parts of butyl acrylate as a (meth)acrylic acid ester monomer, 6 parts of acrylonitrile as a cyano group-containing monomer, 2 parts of methacrylic acid as a hydrophilic group-containing monomer, 10 parts of glycidyl methacrylate as an epoxy group-containing monomer, 0.8 parts of sodium dodecyl diphenyl ether sulfonate as an emulsifier, 20 parts of 10% aqueous ammonia as a pH adjuster, and 54 parts of ion-exchanged water were added and stirred to prepare an emulsion. The prepared emulsion was added sequentially from pressure vessel B to pressure vessel A over approximately 200 minutes, followed by stirring for approximately 180 minutes. The reaction was terminated by cooling when the monomer conversion reached 97% or higher. The emulsion temperature was maintained at 50°C until the monomer conversion reached 97% or higher. The pH was then adjusted with a 4% aqueous solution of NaOH, and unreacted monomer was removed by heating and vacuum distillation to obtain an aqueous dispersion of a particulate polymer (solid concentration: 40%). The pH of the resulting aqueous dispersion was 8.0. The glass transition temperature and volume average particle size of the polymer containing epoxy group-containing monomer units were then measured using the resulting aqueous dispersion. The results are shown in Table 1.

[0100] <Preparation of Slurry Composition for Dielectric Layer> 100 parts by mass of barium titanate ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with a volume average particle diameter (d50) of 0.1 μm as the dielectric material, 5 parts by mass of PVA ("B-33" manufactured by Denka Co., Ltd.) as the water-soluble polymer A (solid content: 50 parts by mass of aqueous solution), and 20 parts by mass of water as the dispersion medium were mixed with 100 parts by mass of zirconia beads (manufactured by Nikkato Corporation) with a particle size of 0.1 mm as mixing beads using a bead mill ("RMB-01" manufactured by Imex Co., Ltd.) at 500 rpm for 2 hours. Then, 20 parts by mass of water was further added, and the mixture was stirred at 500 rpm for 1 hour. The zirconia beads were filtered off to prepare a dispersion of barium titanate. To 190 parts by mass of the above-mentioned barium titanate dispersion (100 parts by mass of barium titanate), 5 parts by mass of the polymer prepared above (12.5 parts by mass as aqueous dispersion) was added, and then the mixture was stirred at 1000 rpm for 3 minutes using a planetary centrifugal mixer to prepare a slurry composition (solid concentration 56%). The dispersion stability of the resulting slurry composition was evaluated, and the results are shown in Table 1.

[0101] <Creating the dielectric layer> The slurry composition obtained above was applied to a release-treated film (PET38AL-5, manufactured by Lintec Corporation) having a width of 100 mm and a length of 100 mm using a gravure coater so that the thickness of the dried green sheet (dry film) would be approximately 1.0 μm, and the coated film was dried in an oven at 100°C for 5 minutes to obtain a dielectric layer (release substrate with dielectric layer) on the release substrate (ceramic green sheet method). The resulting release substrate with a dielectric layer was used to evaluate lamination properties and crack resistance. The results are shown in Table 1.

[0102] Example 2 In preparing the aqueous dispersion of the polymer (binder composition), the amount of butyl acrylate used was changed from 82 parts to 86.5 parts, the amount of acrylonitrile used from 6 parts to 8 parts, the amount of methacrylic acid used from 2 parts to 5 parts, and the amount of glycidyl methacrylate used from 10 parts to 0.5 parts were changed, and the procedures, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0103] Example 3 In preparing the aqueous dispersion of the polymer (binder composition), the amount of butyl acrylate used was changed from 82 parts to 68 parts, the amount of methacrylic acid used from 2 parts to 1 part, and the amount of glycidyl methacrylate used from 10 parts to 25 parts, but the same procedures, measurements, and evaluations were carried out as in Example 1. The results are shown in Table 1.

[0104] Example 4 In preparing the aqueous dispersion of the polymer (binder composition), the amount of sodium dodecyl diphenyl ether sulfonate added to pressure vessel A was changed from 0.2 parts to 0.4 parts, and the amount of sodium dodecyl diphenyl ether sulfonate added to pressure vessel B was changed from 0.8 parts to 1.2 parts. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0105] Example 5 In preparing the aqueous dispersion of the polymer (binder composition), the amount of sodium dodecyl diphenyl ether sulfonate added to pressure vessel A was changed from 0.2 parts to 0.05 parts, and the amount of sodium dodecyl diphenyl ether sulfonate added to pressure vessel B was changed from 0.8 parts to 0.4 parts. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0106] Example 6 In preparing the aqueous dispersion of the polymer (binder composition), the various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that 82 parts of butyl acrylate was changed to 82 parts of 2-ethylhexyl acrylate. The results are shown in Table 1.

[0107] Example 7 Except for changing 82 parts of butyl acrylate to 82 parts of ethyl acrylate in the preparation of the aqueous dispersion of the polymer (binder composition), various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0108] Example 8 In preparing the aqueous dispersion of the polymer (binder composition), the various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that 10 parts of glycidyl methacrylate was changed to 10 parts of allyl glycidyl ether. The results are shown in Table 1.

[0109] Example 9 In preparing the slurry composition for the dielectric layer, various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that the water-soluble polymer A was changed to the water-soluble polymer B prepared by the following method. The results are shown in Table 1.

[0110] <Preparation of Aqueous Solution of Water-Soluble Polymer B> A 5 MPa pressure vessel equipped with a stirrer was charged with 35 parts of methacrylic acid (hydrophilic group-containing monomer), 50 parts of ethyl acrylate ((meth)acrylic acid ester monomer), and 15 parts of n-butyl acrylate ((meth)acrylic acid ester monomer) as a monomer composition, 0.6 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 1 part of potassium persulfate as a polymerization initiator, and after thorough stirring, the vessel was heated to 60°C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling, and further aqueous sodium hydroxide solution was added to adjust the pH to 4, yielding an aqueous solution of water-soluble polymer B (solids concentration 10%).

[0111] (Comparative Example 1) In preparing the aqueous dispersion of the polymer (binder composition), the amount of butyl acrylate used was changed from 82 parts to 87 parts, the amount of acrylonitrile used from 6 parts to 8 parts, and the amount of methacrylic acid used from 2 parts to 5 parts, and glycidyl methacrylate was not used. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0112] (Comparative Example 2) Except for the fact that the binder composition and the slurry composition for the dielectric layer were prepared in the following manner, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0113] <Preparation of Binder Composition> A polymer coagulate was obtained by adding 100 parts by mass of ethanol to the aqueous dispersion of the polymer (binder composition) prepared in Example 1. The ethanol was then removed to separate the coagulate, which was then dissolved in a toluene / ethanol (mass mixing ratio 1:1) solution at 25°C for 5 hours so that the solids concentration of the coagulate became 10%, thereby obtaining a toluene / ethanol-dissolved binder composition (polymer solution) containing the polymer.

[0114] <Preparation of Slurry Composition for Dielectric Layer> 100 parts by mass of barium titanate ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with a volume average particle diameter (d50) of 0.1 μm as the dielectric material, 10 parts by mass of the polymer solution prepared above (100 parts by mass as a toluene / ethanol solution), and 30 parts by mass of a toluene / ethanol (1:1 mass mixing ratio) solution as the dispersion medium were mixed with 100 parts by mass of zirconia beads (manufactured by Nikkato Corporation) with a particle diameter of 0.1 mm as mixing beads, and were stirred at 500 rpm for 2 hours using a bead mill ("RMB-01" manufactured by Imex Co., Ltd.). The zirconia beads were then filtered off to prepare a slurry composition (solids concentration 55%).

[0115] In addition, in Tables 1 and 2 shown below, "BA" indicates n-butyl acrylate units; "2-EHA" indicates 2-ethylhexyl acrylate units, "EA" indicates an ethyl acrylate unit; "MAA" indicates a methacrylic acid unit, "AN" indicates an acrylonitrile unit; "GMA" indicates a glycidyl methacrylate unit; "AGE" represents an allyl glycidyl ether unit, "BaTiO3" refers to barium titanate.

[0116] [Table 1] [Industrial Applicability]

[0117] According to the present invention, it is possible to provide a binder composition for a dielectric layer that can impart excellent crack resistance and lamination properties to a dielectric layer and also excellent dispersion stability to a slurry composition for a dielectric layer. Furthermore, according to the present invention, it is possible to provide a slurry composition for a dielectric layer that can impart excellent crack resistance and lamination properties to the dielectric layer and has excellent dispersion stability. Furthermore, according to the present invention, it is possible to provide a dielectric layer obtained by drying a coating film made of the above-mentioned slurry composition for a dielectric layer. Furthermore, according to the present invention, it is possible to provide a multilayer ceramic capacitor obtained by sintering a laminate in which the above-mentioned dielectric layers are stacked. [Explanation of symbols]

[0118] 10: Multilayer ceramic capacitor 11: Dielectric 12: Internal electrode 13: External electrode

Claims

1. A binder composition for a dielectric layer, comprising a polymer containing an epoxy group-containing monomer unit and water.

2. 2. The binder composition for a dielectric layer according to claim 1, wherein the content of the epoxy group-containing monomer unit is 0.1% by mass or more and 30% by mass or less, when all repeating units contained in the polymer are taken as 100% by mass.

3. 2. The binder composition for a dielectric layer according to claim 1, wherein the polymer further contains a (meth)acrylic acid ester monomer unit.

4. 4. The binder composition for a dielectric layer according to claim 3, wherein the content of the (meth)acrylic acid ester monomer unit is 60% by mass or more and 95% by mass or less, when the total amount of all repeating units contained in the polymer is 100% by mass.

5. 2. The binder composition for a dielectric layer according to claim 1, wherein the polymer is water-insoluble.

6. the polymer is in particulate form, 2. The binder composition for a dielectric layer according to claim 1, wherein the polymer has a volume average particle size of 0.01 μm or more and 0.5 μm or less.

7. 2. The binder composition for a dielectric layer according to claim 1, wherein the polymer has a glass transition temperature of -60°C or higher and 0°C or lower.

8. A slurry composition for a dielectric layer, comprising the binder composition for a dielectric layer according to any one of claims 1 to 7 and a dielectric material.

9. A dielectric layer obtained by drying a coating film made of the slurry composition for a dielectric layer according to claim 8.

10. A multilayer ceramic capacitor obtained by sintering a laminate in which the dielectric layers according to claim 9 are stacked.

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