TW202424008A - Binder composition for dielectric layer, slurry composition for dielectric layer, dielectric layer, and capacitor - Google Patents

Abstract

The purpose of the present invention is to provide a binder composition for a dielectric layer, which is capable of imparting excellent blocking resistance to the dielectric layer. The present invention is a binder composition for a dielectric layer, said binder composition including a polymer and a solvent, wherein the polymer contains a conjugated diene monomer unit and has a glass transition temperature of -45 DEG C or higher.

Description

Dielectric layer binder composition, dielectric layer slurry composition, dielectric layer and capacitor

The present invention relates to a binder composition for a dielectric layer, a slurry composition for a dielectric layer, a dielectric layer and a capacitor.

Capacitors such as stacked ceramic capacitors are generally obtained by forming dielectric layers such as ceramic green sheets, stacking the dielectric layers, and sintering them randomly.

The dielectric layer can be obtained, for example, by first preparing a slurry composition including a binder, a dielectric material and a solvent, then applying the slurry composition on a release substrate, and then drying. Then, the obtained dielectric layer can be used in the manufacture of a capacitor.

In recent years, there has been progress in the development of binders included in slurry compositions used in the manufacture of dielectric layers in order to impart excellent characteristics to capacitors.

For example, in Patent Document 1, a binder for manufacturing an inorganic sintered body is proposed, which, when used as a binder for manufacturing ceramic green sheets, can achieve a high porosity while having a specified gel component ratio and comprising a binder resin composition containing a specified composite resin as a binder with excellent thermal decomposition properties that can manufacture ceramic green sheets that are not prone to defects such as cracks when manufacturing sintered bodies.

"Patent Document" "Patent Document 1": Japanese Patent Publication No. 2018-165230

Here, after a dielectric layer such as a ceramic green sheet is formed on a release substrate, it is usually rolled up together with the release substrate. If rolled up, the dielectric layer will be in close contact with the surface of the release substrate on the side where the dielectric layer is not formed (hereinafter sometimes referred to as the "back side of the release substrate"). However, if stored in this state, the dielectric layer and the back side of the release substrate may be fixed (so-called agglomeration), and there is a risk of causing the dielectric layer to break.

The inventors of the present invention have conducted intensive research with the purpose of solving the above-mentioned problems. Then, the inventors of the present invention have newly discovered that if a dielectric layer binder composition comprising a polymer containing a specified monomer unit and a solvent is used, and the glass transition temperature of the polymer is above the specified temperature, the above-mentioned problems can be solved, and the present invention has been completed.

That is, the purpose of this invention is to successfully solve the above-mentioned problems. [1] The present invention is a dielectric layer binder composition, which is a dielectric layer binder composition comprising a polymer and a solvent, wherein the aforementioned polymer contains a conjugated diene monomer unit and has a glass transition temperature of above -45°C.

When the above-mentioned binder composition for a dielectric layer is used, excellent anti-blocking property can be imparted to the dielectric layer.

Furthermore, when the above-mentioned adhesive composition for a dielectric layer is used, the dielectric layer formed on the release substrate can be prevented from being unintentionally peeled off from the release substrate. In other words, when the above-mentioned adhesive composition for a dielectric layer is used, excellent bonding properties can be imparted to the dielectric layer.

Furthermore, if the above-mentioned dielectric layer binder composition is used, when the dielectric layer is laminated with other layers and pressed, the dielectric layer can be peeled off from the release substrate in the production of capacitors, and the dielectric layer can be suppressed from remaining on the release substrate. In other words, if the above-mentioned dielectric layer binder composition is used, the dielectric layer can be given excellent transferability.

In this specification, the glass transition temperature of a polymer can be measured according to the method described in the examples.

[2] In the adhesive composition for a dielectric layer of the above-mentioned [1], the glass transition temperature is preferably below 20°C.

If the glass transition temperature is below the upper limit, the transferability of the dielectric layer can be improved.

[3] In the binder composition for a dielectric layer of [1] or [2], the tetrahydrofuran-insoluble content of the polymer is preferably 70% by mass or more.

When the tetrahydrofuran (THF) insoluble content of the polymer is greater than or equal to the above lower limit, the anti-blocking property of the dielectric layer can be improved.

In this specification, the THF insoluble content of a polymer can be measured according to the method described in the Examples.

[4] In the binder composition for a dielectric layer according to any one of [1] to [3] above, the polymer is a particulate polymer, and the average particle size of the particulate polymer is preferably not less than 0.01 μm and not more than 1.0 μm.

If the polymer is a particulate polymer, the polymer can be uniformly dispersed in the dielectric layer when the dielectric layer is formed, thereby improving the performance of the dielectric layer.

When the average particle size of the particulate polymer is equal to or larger than the above lower limit, the bonding property and transferability of the dielectric layer can be improved.

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

In this specification, the average particle size of the particulate polymer can be measured according to the method described in the examples.

[5] In the binder composition for a dielectric layer according to any one of [1] to [4] above, the polymer preferably further contains an aromatic vinyl monomer unit.

If the polymer further contains aromatic vinyl monomer units, the anti-blocking property of the dielectric layer can be improved.

[6] In the binder composition for a dielectric layer according to any one of [1] to [5] above, the solvent is preferably water or an aqueous solvent.

If the solvent is water or an aqueous solvent, the anti-blocking property and transferability of the dielectric layer can be improved.

[7] In the binder composition for a dielectric layer according to any one of [1] to [6], the content of the covalent diene monomer units is preferably 20% by mass or more and 60% by mass or less, based on 100% by mass of all the monomer units contained in the polymer.

When the content ratio of the conjugated diene monomer unit is equal to or greater than the above lower limit, the bonding property and transferability of the dielectric layer can be improved.

On the other hand, when the content ratio of the conjugated diene monomer unit is below the above upper limit, the anti-blocking property of the dielectric layer can be improved.

In this specification, the content ratio of various repeating units (monomer units) in a polymer can be measured using a nuclear magnetic resonance (NMR) method such as ¹ H-NMR.

Furthermore, the present invention is aimed at successfully solving the above-mentioned problems. [8] The present invention is a dielectric layer binder composition comprising any one of the above-mentioned [1] to [7] and a dielectric layer slurry composition of a dielectric material.

When the dielectric layer slurry composition is used, excellent anti-blocking property can be imparted to the dielectric layer. Also, when the dielectric layer slurry composition is used, excellent bonding property and transferability can be imparted to the dielectric layer.

Furthermore, this invention is aimed at successfully solving the above-mentioned problems. [9] The present invention is a dielectric layer formed by drying a coating film made of the dielectric layer slurry composition described in [8] above.

The dielectric layer is easy to handle due to its excellent anti-blocking properties, bonding properties and transferability, and as a result, capacitors can be efficiently produced.

Furthermore, this invention is aimed at successfully solving the above-mentioned problem. [10] The present invention is a capacitor formed by using the dielectric layer of the above-mentioned [9].

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

According to the present invention, an adhesive composition for a dielectric layer which can impart excellent anti-blocking properties to the dielectric layer can be provided.

Furthermore, according to the present invention, a slurry composition for a dielectric layer which imparts excellent anti-caking properties to the dielectric layer can be provided.

Furthermore, according to the present invention, a dielectric layer formed by drying a coating film formed of the above-mentioned dielectric layer slurry composition can be provided.

Furthermore, according to the present invention, a capacitor formed using the above-mentioned dielectric layer can be provided.

The following is a detailed description of the implementation of the present invention.

Here, the binder composition for dielectric layer of the present invention (hereinafter simply referred to as "binder composition" sometimes) can be used for preparing the slurry composition for dielectric layer of the present invention (hereinafter simply referred to as "slurry composition" sometimes). Moreover, the slurry composition of the present invention can be used for forming 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 by the slurry composition of the present invention. Furthermore, the capacitor of the present invention is formed by using "the dielectric layer formed by using the slurry composition of the present invention".

(Adhesive composition for dielectric layer)

The adhesive composition for the dielectric layer of the present invention includes a polymer and a solvent, and may also arbitrarily include components other than the polymer and the solvent (hereinafter sometimes referred to as "other components"). Then, in the adhesive composition of the present invention, the polymer contains a covalent diene monomer unit and the glass transition temperature is above -45°C. If such an adhesive composition is used, excellent anti-blocking properties can be imparted to the dielectric layer. In addition, if such an adhesive composition is used, excellent bonding and transfer properties can be imparted to the dielectric layer. The reasons for this are presumably as follows: the covalent diene monomer units contained in the polymer impart excellent bonding and transfer properties to the dielectric layer, and by making the glass transition temperature of the polymer above -45°C, excessive softening of the polymer is suppressed, thereby achieving excellent anti-blocking properties of the dielectric layer.

In addition, in this specification, the binder composition is generally not included in the dielectric material described later.

<polymer>

The polymer contained in the adhesive composition of the present invention is a component that can function as a binder, and contains a conjugated diene monomer unit, and may also contain an aromatic vinyl monomer unit, an acid group-containing monomer unit, and a cyano group-containing monomer unit. In addition, the polymer may also contain monomer units other than the conjugated diene monomer unit, the aromatic vinyl monomer unit, the acid group-containing monomer unit, and the cyano group-containing monomer unit (hereinafter sometimes referred to as "other monomer units").

Here, examples of polymers containing covalent diene monomer units include copolymers containing aromatic vinyl monomer units such as styrene-butadiene copolymers (SBR) and covalent diene monomer units, butadiene rubber (BR), isoprene rubber, acrylic rubber (NBR) (containing copolymers containing cyano group-containing monomer units and covalent diene monomer units), and hydrogenated products thereof.

《Conjugated diene monomer unit》

The conjugated diene monomer unit is a monomer unit formed by a conjugated diene monomer. Examples of the conjugated diene monomer include 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, and substituted and side-chain conjugated hexadienes. These can be used alone or in combination of two or more. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene) are preferred as the conjugated diene monomer, and 1,3-butadiene is more preferred.

The content ratio of the covalent diene monomer unit is preferably 20 mass % or more, more preferably 25 mass % or more, and preferably 60 mass % or less, more preferably 55 mass % or less, when all repeating units (all monomer units) contained in the polymer are taken as 100 mass %.

When the content ratio of the conjugated diene monomer unit is greater than or equal to the above lower limit, the bonding property and transferability of the dielectric layer can be improved.

On the other hand, when the content ratio of the conjugated diene monomer unit is below the above upper limit, the anti-blocking property of the dielectric layer can be improved.

《Aromatic vinyl monomer unit》

The aromatic vinyl monomer unit is a monomer unit formed by an aromatic vinyl monomer. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, and divinylbenzene. These may be used alone or in combination of two or more. Among these, styrene is preferred as the aromatic vinyl monomer.

The content ratio of the aromatic vinyl monomer unit is preferably 30 mass % or more, more preferably 40 mass % or more, more preferably 45 mass % or more, and preferably 70 mass % or less, and more preferably 65 mass % or less, when all repeating units (all monomer units) contained in the polymer are taken as 100 mass %.

When the content ratio of the aromatic vinyl monomer unit is greater than the above lower limit, the anti-blocking property of the dielectric layer can be improved.

On the other hand, when the content ratio of the aromatic vinyl monomer unit is below the above upper limit, the transferability of the dielectric layer can be improved.

《Acid-containing monomer unit》

The acid group-containing monomer unit is a monomer unit formed by an acid group-containing monomer. Examples of the acid group-containing monomer include an acid group-containing monomer and a sulfonic acid group-containing monomer.

As the carboxylic acid group-containing monomer unit, there can be mentioned: monocarboxylic acid and its derivatives or dicarboxylic acid and its anhydride and their derivatives.

As monocarboxylic acids, there are acrylic acid, methacrylic acid, crotonic acid, and the like.

As the monocarboxylic acid derivatives, there can be mentioned 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-transaryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid and the like.

Examples of dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, and the like.

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

Examples of the anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, and conic anhydride.

Furthermore, as the carboxylic acid group-containing monomer, an acid anhydride which generates a carboxylic acid group by hydrolysis may be used.

Furthermore, as the carboxylic acid group-containing monomer, ethylenically unsaturated polycarboxylic acids such as butenetricarboxylic acid or partial esters of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate and mono(2-hydroxypropyl)maleate may be used.

Examples of the sulfonic acid group-containing monomer include ethylene sulfonic acid, methylethylene sulfonic acid, (methyl)allyl sulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

In addition, in this specification, the term "(meth)allyl group" means allyl group and/or methallyl group.

As the acid group-containing monomer, acrylic acid, methacrylic acid, itaconic acid and vinyl sulfonic acid are preferred, and acrylic acid, methacrylic acid and itaconic acid are more preferred.

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, and more preferably 5 mass % or less, when all repeating units (all monomer units) contained in the polymer are defined as 100 mass %.

If the content ratio of the acid group-containing monomer unit is greater than the above lower limit, the dispersion stability of the polymer in the binder composition and the slurry composition can be improved.

On the other hand, if the content ratio of the acid group-containing monomer unit is below the above upper limit, the anti-blocking property of the dielectric layer can be improved.

《Cyanide-containing monomers》

The cyano-containing monomer unit is a monomer unit formed by a cyano-containing monomer. Examples of the cyano-containing monomer include acrylonitrile and methacrylonitrile. These monomers may be used alone or in combination of two or more monomers at any ratio. Among these monomers, acrylonitrile is preferred as the cyano-containing monomer.

The cyano group-containing monomer unit is preferably 5 mass % or more, more preferably 10 mass % or more, and is preferably 25 mass % or less, and more preferably 20 mass % or less, when all repeating units (all monomer units) contained in the polymer are taken as 100 mass %.

If the content ratio of the cyano group-containing monomer unit is greater than the above lower limit, the anti-blocking property of the dielectric layer can be improved.

On the other hand, when the content ratio of the cyano group-containing monomer unit is below the above upper limit, the transferability of the dielectric layer can be improved.

《Other individual units》

Other monomer units are monomer units that can be formed by other monomers. Other monomers are not particularly limited as long as they are monomers that can be copolymerized with the monomers mentioned above. Examples of other monomers include: amide-containing monomers such as acrylamide and methacrylamide; crosslinking monomers (monomers capable of crosslinking) such as allyl glycidyl ether, allyl (meth)acrylate, and N-hydroxymethyl acrylamide; olefins such as ethylene and propylene; halogen atom-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; methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, isopropenyl vinyl ketone, etc. Vinyl ketones; N-vinylpyrrolidone, vinylpyridine, vinylimidazole and other heterocyclic vinyl compounds; aminoethyl vinyl ether, dimethylaminoethyl vinyl ether and other amine-containing monomers; (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and other octyl (meth)acrylates; etc. These other monomers may be used alone or in combination of two or more.

In the present specification, "(meth)acrylate" means acrylate and/or methacrylate, and "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

The content ratio of other monomer units, when all repeating units (all monomer units) contained in the polymer is defined as 100 mass %, is preferably 10 mass % or less, more preferably 5 mass % or less, more preferably 1 mass % or less, and even more preferably 0 mass % (i.e., the polymer contains no other monomer units).

《Properties of polymers》

In the adhesive composition of the present invention, the glass transition temperature of the polymer must be above -45°C.

Then, the glass transition temperature of the polymer is preferably not less than −30°C, more preferably not less than −25°C, and preferably not more than 20°C, more preferably not more than 15°C.

If the glass transition temperature of the polymer is above −30°C, the anti-blocking property of the dielectric layer can be improved.

On the other hand, if the glass transition temperature of the polymer is 20° C. or lower, the transferability of the dielectric layer can be improved.

The THF-insoluble content of the polymer is preferably 70 mass % or more, more preferably 75 mass % or more, and is preferably 100 mass % or less, more preferably 98 mass % or less.

When the THF insoluble content of the polymer is greater than or equal to the above lower limit, the anti-blocking property of the dielectric layer can be improved.

On the other hand, when the THF-insoluble content of the polymer is equal to or less than the upper limit, the bonding property and transferability of the dielectric layer can be improved.

The polymer contained in the binder composition of the present invention is preferably a particle-shaped polymer. If the polymer is a particle-shaped polymer, when forming a dielectric layer, the polymer can be uniformly dispersed in the dielectric layer, thereby improving the performance of the dielectric layer.

In the binder composition, when the polymer is a particulate polymer, the average particle size of the particulate polymer is preferably 0.01 μm or more, more preferably 0.02 μm or more, and preferably 1.0 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less.

When the average particle size of the particulate polymer is equal to or larger than the above lower limit, the bonding property and transferability of the dielectric layer can be improved.

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

《Polymerization method of polymer》

The polymerization method of the polymer is not particularly limited. For example, any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. can be used. In addition, as the polymerization reaction, addition polymerization such as ion polymerization, free radical polymerization, and living free radical polymerization can be used. Then, the polymerization solvent or emulsifier, dispersant, polymerization initiator, chain transfer agent and other additives used in the polymerization can be generally used, and the amount used can also be set to the amount generally used.

〈Solvent〉

The solvent included in the adhesive composition of the present invention is not particularly limited, and any of water and organic solvents can be used. As the organic solvent, aqueous solvents such as lower alcohols such as methanol, ethanol, and isopropanol, and non-aqueous solvents such as methylbenzene (toluene) and xylene can be used.

In terms of improving the anti-blocking property and transferability of the dielectric layer, water or an aqueous solvent is preferred as the solvent. In terms of reducing environmental load, safety, and easy availability, water is particularly preferred as the solvent.

〈Other ingredients〉

The adhesive composition of the present invention may also contain other components. As other components, for example, the above-mentioned additives or viscosity modifiers used when polymerizing the polymer can be listed. In addition, polyvinyl butyral can be used as a viscosity modifier.

〈Concentration of solid content in the binder composition for dielectric layer〉

The solid content concentration of the binder composition is preferably 20 mass % or more, more preferably 30 mass % or more, and preferably 60 mass % or less, more preferably 50 mass % or less.

〈Method for preparing adhesive composition for dielectric layer〉

The binder composition of the present invention can be prepared by mixing the polymer, solvent and any other components mentioned above in a known manner. Specifically, the binder composition can be prepared by mixing the above components using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a mortar, an ultrasonic disperser, a homogenizer, a planetary mixer, a film rotary mixer (FILMIX), a rotational-revolutionary mixer, or the like.

(Slurry composition for dielectric layer)

The slurry composition for the dielectric layer of the present invention includes the binder composition and the dielectric material of the present invention described above. That is, the slurry composition of the present invention includes a polymer, a solvent and a dielectric material. Here, the solvent included in the slurry composition may be entirely derived from the binder composition, or may be different from the solvent derived from the binder composition and newly added to the slurry composition. The slurry composition of the present invention may also include components other than the polymer, the solvent and the dielectric material (hereinafter sometimes referred to as "other components").

Furthermore, the slurry composition of the present invention can provide excellent anti-caking properties to the dielectric layer because it contains the binder composition of the present invention. Furthermore, the slurry composition of the present invention can provide excellent bonding and transfer properties to the dielectric layer because it contains the binder composition of the present invention.

〈Dielectric Materials〉

The dielectric material is not particularly limited as long as it has dielectric properties, but ceramic materials are preferably used. Examples of the ceramic material include zirconium oxide, aluminum silicate, titanium oxide, zinc oxide, barium titanate, calcium zirconate, calcium titanate, strontium titanate, magnesium oxide, sialon ceramics, spinel, silicon carbide, silicon nitride, aluminum nitride, etc. These ceramic materials may be used alone or in combination of two or more.

Here, as the ceramic material, a ceramic material having a calcite structure represented by the general formula ABO ₃ as the main phase is preferably used. Examples of the ceramic material include barium titanate (BaTiO ₃ ), calcium zirconate (CaZrO ₃ ), calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), and Ba _1−x−y Ca _{x Sry} Ti _1−z Zr _z O ₃ (0≦x≦1, 0≦y≦1, 0≦z≦1) forming a calcite structure. Among these, barium titanate is preferably used as the ceramic material having a calcite structure as the main phase.

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

If the 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. As a result, a dielectric layer in which the dielectric material is uniformly dispersed can be produced.

In this specification, the average particle size of the dielectric material means the particle size at which the cumulative volume calculated from the small diameter side accounts for 50% of the particle size distribution (volume basis) measured by laser diffraction.

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, and more preferably 70 mass % or less, when all components in the slurry composition (including the solvent) are taken as 100 mass %.

〈Solvent〉

The solvent contained in the slurry composition of the present invention may be the same as the solvent described in the item "Solvent" of the "Binder composition for dielectric layer" mentioned above.

〈Other ingredients〉

As other components that may be included in the slurry composition of the present invention, the same ones as those described in the item of "other components" of the above-mentioned "binder composition for dielectric layer" can be cited.

Here, when a viscosity adjuster is used as another component, the content (solid content) of the viscosity adjuster in the slurry composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and 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.

〈Solid content concentration of dielectric layer slurry composition〉

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

〈Polymer content〉

The content (solid content) of the polymer in the slurry composition is preferably 1 part by mass or more, more preferably 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 slurry composition.

〈Method for preparing slurry composition for dielectric layer〉

The slurry composition described above can be prepared by mixing the above-mentioned components by a known mixing method. As a mixer used for the preparation, the mixer listed in the above-mentioned "Preparation method of the binder composition for dielectric layer" can be cited.

(Dielectric layer)

The dielectric layer of the present invention is formed by drying a coating film made of the 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 the coating film made of the slurry composition of the present invention. That is, the dielectric layer of the present invention includes the polymer and dielectric material mentioned above, and optionally includes a solvent and other components.

Here, since the dielectric layer of the present invention is formed by drying a coating film formed by the slurry composition of the present invention, it has excellent anti-caking properties, bonding properties and transfer properties. In addition, since the dielectric layer of the present invention has excellent anti-caking properties, bonding properties and transfer properties, it is easy to operate, and as a result, capacitors can be efficiently produced.

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

The content of the polymer in the dielectric layer is preferably 1 part by mass or more, more preferably 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.

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.

The dielectric layer of the present invention may also have a conductive layer formed on the dielectric layer. The conductive layer may be formed by various printing methods such as screen printing, rotogravure printing, plate printing, inkjet printing, and lithography using patterns formed by these methods, and vacuum evaporation for forming a metal evaporation film.

Here, when the conductive 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 of metal or the like, a dispersant, a plasticizer, a solvent, etc., with polyvinyl acetal resin.

〈Method for manufacturing dielectric layer〉

The dielectric layer can be manufactured by coating the slurry composition of the present invention on a release substrate and drying the formed coating film.

Here, the release substrate used in making the dielectric layer is made of a flexible resin. Since the release substrate is made of a flexible resin, the slurry composition can be applied to the release substrate, and the release substrate (stacked film) formed by the dielectric layer obtained by drying can be stored in a rolled state and supplied according to demand.

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

The release substrate is preferably subjected to a surface treatment for improving release properties 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 silicone release agent, a fluorine release agent, a wax release agent, and the like.

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

The method for coating the slurry composition on the release substrate is not particularly limited, and examples thereof include a well-known coating method using various roll coaters represented by a coater or a rotogravure coater and a doctor blade coater (registered trademark).

The drying method of the coating film formed on the release substrate is not particularly limited, and for example, a well-known drying method using a hot air dryer can be cited. In addition, the drying conditions can be appropriately set according to 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 more and 150°C or less, and the drying time is usually 3 minutes or more and 60 minutes or less.

Furthermore, when the dielectric layer of the present invention is used in the manufacture of capacitors, multiple dielectric layers may be stacked and then heat-pressed. However, the peeling of the dielectric layer from the release substrate described above may be performed before the stacking and heat-pressing of the dielectric layers, or after the stacking and heat-pressing of the dielectric layers.

(Capacitor)

The capacitor of the present invention is made by using the dielectric layer of the present invention described above. Since the capacitor of the present invention uses the dielectric layer which is easy to handle, the productivity is excellent.

Here, as the capacitor of the present invention, there can be exemplified a capacitor obtained by sintering a stacked body having dielectric layers stacked thereon (sintered product) and a capacitor obtained by not sintering a stacked body having dielectric layers stacked thereon (unsintered product).

As a capacitor formed by sintering the above-mentioned stacked body, for example, a stacked ceramic capacitor can be cited.

Examples of capacitors obtained without sintering the stack include stacked metallized thin film capacitors.

In addition, the following description takes the case where the capacitor is a stacked ceramic capacitor as an example, but the present invention is not limited to the following example.

The stacked 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. An example of the stacked ceramic capacitor as the capacitor of the present invention is described below with reference to FIG. 1.

Fig. 1 is a schematic cross-sectional view showing an example of a stacked ceramic capacitor as a capacitor of the present invention. The stacked ceramic capacitor 10 shown in Fig. 1 has alternately stacked layered dielectrics 11 and layered internal electrodes 12, and has a pair of external electrodes 13 outside the dielectrics 11 and the internal electrodes 12. Furthermore, one of the pair of inner electrodes 12 adjacent to each other along the stacking direction sandwiching the dielectric 11 is electrically connected to one of the pair of outer electrodes 13 in the interior of the stacked ceramic capacitor 10, and the other of the pair of inner electrodes 12 adjacent to each other along the stacking direction sandwiching the dielectric 11 is electrically connected to the other of the pair of outer electrodes 13 in the interior of the stacked ceramic capacitor 10. Thus, a structure in which a plurality of capacitor elements are electrically connected in parallel is formed between the pair of outer electrodes 13. In addition, the interface between the dielectric layers formed when the dielectric layers of the present invention are stacked is not shown in FIG. 1 because the dielectric layers are integrated and eliminated by sintering.

The stacked ceramic capacitor is not particularly limited and can be manufactured by a conventionally known method. For example, the stacked ceramic capacitor can be manufactured by stacking a plurality of dielectric layers of the present invention having a conductive layer to be an internal electrode in such a manner that the dielectric layer and the conductive layer are alternately stacked, and the stack is heat-pressed to produce a stack, and the binder components and the like contained in the stack are removed by thermal decomposition (degreasing treatment), and the stack is further sintered, and then the external electrode is formed on the end surface of the ceramic sintered product obtained by sintering.

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.

In addition, the content of binder components in the degreased stack is usually less than 50 ppm.

The degreased stack is usually sintered in a reducing gas atmosphere such as H ₂ -N ₂ -H ₂ O gas with an oxygen partial pressure of 10 ⁻⁹ to 10 ⁻¹² MPa at a temperature of 1000°C to 1500°C. The sintering time of the stack is usually 1 hour to 30 hours.

The external electrode can be formed by applying the external electrode material to the end surface of the ceramic sintered product obtained by sintering and baking it. In this way, for example, a stacked ceramic capacitor as a capacitor shown in FIG. 1 can be obtained.

Examples of materials for the external electrode include Cu glue containing glass glue, etc. Baking is usually performed in a nitrogen atmosphere at a temperature of 500°C or higher and 1500°C or lower. In addition, the surface of the external electrode may be plated with Ni or Sn, etc.

『Implementation example』

The present invention is specifically described below based on the embodiments, but the present invention is not limited to these embodiments. In addition, in the following description, "%" and "parts" representing the amount are based on mass unless otherwise noted.

Furthermore, in a polymer produced by polymerizing a plurality of monomers, the ratio of a monomer unit formed by polymerizing a certain monomer in the polymer is usually consistent with the ratio (incorporation ratio) of the monomer to all monomers used in the polymerization of the polymer, unless otherwise noted.

Furthermore, in the Examples and Comparative Examples, the glass transition temperature of the polymer, the average particle size of the polymer (in particle form), the THF insoluble content of the polymer, the anti-caking property, the transferability and the bonding property were measured and evaluated by the following procedures.

〈Glass transition temperature of polymers〉

The dispersion (solution) of the polymer prepared in the examples and comparative examples was dried for 3 days at 50% humidity and 25°C to obtain a film with a thickness of 1.0 mm. The film was dried at 60°C for 10 hours using a vacuum dryer. Thereafter, the dried film was used as a sample and the glass transition temperature (°C) was 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.

〈Average particle size of polymer (particles)〉

The average particle size of the polymer was measured by laser diffraction as follows.

First, the dispersion of the polymer (in particle form) prepared in Example was adjusted to a solid content concentration of 0.1 mass % to prepare a sample for measurement. Then, in the particle size distribution (volume basis) measured using a laser diffraction particle size distribution measuring device (manufactured by Beckman Coulter, product name "LS-230"), the particle size D50 at which the cumulative volume calculated from the small diameter side becomes 50% was determined as the average particle size.

〈THF insoluble content of polymer〉

The polymer dispersion (solution) prepared in the Examples and Comparative Examples was dried in an environment of 50% humidity and 23-25°C to form a film with a thickness of about 0.3 mm. The film was cut into 3 mm squares and weighed accurately. The mass of the film obtained by cutting was defined as w0.

The film piece was immersed in 100 g of tetrahydrofuran (THF) at 25° C. for 24 hours. Then, the film piece pulled up from THF was vacuum dried at 105° C. for 3 hours, and the mass w1 of the insoluble component was measured.

Then, the THF insoluble content ratio (mass %) is calculated according to the following formula (1). THF insoluble content ratio (mass %) = (w1/w0) × 100 (1)

〈Anti-caking properties〉

The dielectric layer is peeled off from the release substrate with a dielectric layer manufactured in the embodiments and comparative examples, and the peeled dielectric layer is cut into a square with a width of 5 cm and a length of 5 cm to make a test piece. A polyethylene terephthalate (PET) film is prepared, and the PET film and the test piece (dielectric layer) are overlapped and placed at 40°C and a pressure of 10 kg/ ^cm2 for 24 hours. The state (blocking state) of the dielectric layer bonded to the PET film after being placed for 24 hours is visually confirmed, and the anti-blocking property is evaluated according to the following criteria. A: The dielectric layer does not agglomerate on the PET film B: The dielectric layer agglomerates on the PET film, but can be peeled off C: The dielectric layer agglomerates on the PET film and cannot be peeled off

〈Transferability〉

The release substrate with a dielectric layer produced in the embodiment and the comparative example was cut into a square with a width of 5 cm and a length of 5 cm to prepare a test piece.

Two of the above test pieces were prepared, stacked with the dielectric layers facing each other, and pressed at 40°C and 5 kg/ ^cm2 for 10 seconds.

After that, the release substrate of one of the test pieces was peeled off, and the peeling state (transferability) of the dielectric layer was visually confirmed, and the transferability was evaluated according to the following criteria. A: The dielectric layers were bonded to each other, and the dielectric layer did not remain on the surface of the peeled release substrate.B: The dielectric layers were bonded to each other, but part of the dielectric layer remained on the surface of the peeled release substrate.C: The dielectric layers were not bonded to each other, and almost all of the dielectric layer remained on the surface of the release substrate.

〈Joinability〉

The release substrate with a dielectric layer manufactured in the embodiment and the comparative example was cut into a rectangle with a width of 10 mm and a length of 100 mm to make a test piece. A cellovan tape (specified in JISZ1522) was attached to the dielectric layer of the test piece. The cellovan tape was fixed on the horizontal surface of the test bench in a flat state, and one end of the release substrate was stretched vertically relative to the cellovan tape surface at a tensile speed of 10 mm/minute to be peeled off, and the stress at this time was measured. The measurement was performed 3 times, and the average value was calculated and determined as the peeling strength, which was evaluated by the following criteria. The greater the peeling strength, the better the bonding between the dielectric layer and the release substrate. A: Peeling strength is 50 N/m or moreB: Peeling strength is 10 N/m or more and less than 50 N/mC: Peeling strength is less than 10 N/m

(Example 1)

〈Preparation of polymer dispersion (binder composition)〉

In a 5 MPa pressure-resistant container equipped with a stirrer, 33 parts of 1,3-butadiene (BD), 3.8 parts of itaconic acid (IA), and 63.2 parts of styrene (ST) as monomer components, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium peroxodisulfate as a polymerization initiator were added, and after sufficient stirring, the mixture was heated to 50°C to start polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a polymer.

A 5% sodium hydroxide aqueous solution was added to the mixture containing the above polymer, and the pH was adjusted to 8, and then the unreacted monomers were removed by heating and reducing pressure distillation. After that, the mixture was cooled to below 30°C to obtain a dispersion containing the desired polymer (the solvent was water). In addition, the solid content concentration of the dispersion was 40%.

The obtained dispersion was used to measure the glass transition temperature of the polymer, the average particle size of the polymer (in particle form), and the THF insoluble content of the polymer. The results are shown in Table 1.

〈Preparation of pulp composition〉

100 parts of barium titanium oxide ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with an average particle size (d50) of 0.1 μm as a dielectric material, 12.5 parts of an aqueous solution of polyvinyl butyral ("BL-2H" manufactured by Sekisui Chemical Industry Co., Ltd.) as a viscosity adjuster (5 parts in terms of solid content), 20 parts of water as a solvent, and 100 parts of zirconia beads ("RMB-01" manufactured by NIKKATO CORPORATION) with a particle size of 0.1 mm as mixing beads were stirred at 500 rpm for 20 hours using a bead mill ("RMB-01" manufactured by Amicus Co., Ltd.). After that, 20 parts of water was further added and stirred at 500 rpm for 10 hours. The zirconia beads were filtered out to prepare a dispersion of barium titanium oxide.

12.5 parts of the polymer dispersion prepared above (containing 5 parts of the polymer) were added to 152.5 parts of the barium titanium oxide dispersion (containing 100 parts of barium titanium oxide), and the mixture was stirred at 1000 rpm for 3 minutes using a rotary mixer to prepare a slurry composition.

〈Fabrication of Dielectric Layer〉

The slurry composition obtained above was coated on a film (PET38AL-5 manufactured by Lintec Corporation) with a width of 100 mm and a length of 100 mm by a rotogravure coating machine in such a way that the thickness of the dielectric layer after drying was about 1.0 μm. It was dried at 100°C for 5 minutes in the atmosphere, and a dielectric layer was prepared on the release substrate (ceramic green sheet method). The release substrate with the dielectric layer obtained was used to evaluate the anti-blocking property, transferability and bonding property. The results are shown in Table 1.

(Example 2)

Except that 50 parts of 1,3-butadiene (BD), 3.8 parts of itaconic acid (IA), 31.2 parts of styrene (ST) and 15 parts of acrylonitrile (AN) were used as the monomer composition in the preparation of the polymer dispersion, various operations, measurements and evaluations were carried out in accordance with Example 1. The results are shown in Table 1.

(Example 3)

Except that toluene was used as a solvent in the preparation of the polymer dispersion and the slurry composition, specifically, the polymer dispersion and the slurry composition were prepared in the following manner, various operations, measurements and evaluations were performed in accordance with Example 1. The results are shown in Table 1.

〈Preparation of polymer dispersion (binder composition)〉

In a 5 MPa pressure-resistant container equipped with a stirrer, 33 parts of 1,3-butadiene (BD), 3.8 parts of itaconic acid (IA), and 63.2 parts of styrene (ST) as monomer components, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium peroxodisulfate as a polymerization initiator were added, and after sufficient stirring, the mixture was heated to 50°C to start polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a polymer.

Toluene was added to the mixture containing the above polymer, and the unreacted monomers and ion exchange water were removed by heating and reducing pressure distillation to perform solvent replacement. After that, the mixture was cooled to below 30°C to obtain a dispersion containing the desired polymer (the solvent was toluene). In addition, the solid content concentration of the dispersion was 40%.

〈Preparation of pulp composition〉

100 parts of barium titanium oxide ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.) with an average particle size (d50) of 0.1 μm as a dielectric material, 5 parts of polyvinyl butyral ("BL-2H" manufactured by Sekisui Chemical Industry Co., Ltd.) as a viscosity adjuster, 20 parts of toluene as a solvent, and 100 parts of zirconia beads ("RMB-01" manufactured by NIKKATO CORPORATION) 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 Amicus Co., Ltd.). Then, 20 parts of toluene were further added and stirred at 500 rpm for 1 hour. The zirconia beads were filtered out to prepare a dispersion of barium titanium oxide.

12.5 parts of the polymer dispersion prepared above (containing 5 parts of the polymer) were added to 152.5 parts of the barium titanium oxide dispersion (containing 100 parts of barium titanium oxide), and the mixture was stirred at 1000 rpm for 3 minutes using a rotary mixer to prepare a slurry composition.

(Comparison Example 1)

Except that a solution of a polymer composed of a homopolymer of 1,3-butadiene (BD) (the solvent is toluene) was used instead of the polymer dispersion, various operations, measurements and evaluations were performed in the same manner as in Example 3. The results are shown in Table 1.

In addition, in Comparative Example 1, since the polymer was dissolved in toluene, the average particle size of the polymer was not measured.

"Table 1" Embodiment Comparison Example 1 2 3 1 Binder composition polymer Composition [mass %] BD 33 50 33 100 ST 63.2 31.2 63.2 - I A 3.8 3.8 3.8 - AN - 15 - - Glass transition temperature[℃] 10 −5 10 −48 THF insoluble content [mass %] 92 72 92 80 Average particle size [µm] 0.12 0.15 0.16 - Solvent Type water water Toluene Toluene Solid content concentration [mass %] 40 40 40 40 Evaluation results Anti-caking A B B C Transferability A A B C Gygosity A A A A

As shown in Table 1, if the polymer dispersion (binder composition) of the embodiment is used, excellent anti-blocking properties can be imparted to the dielectric layer.

According to the present invention, an adhesive composition for a dielectric layer which can impart excellent anti-blocking properties to the dielectric layer can be provided.

Furthermore, according to the present invention, a slurry composition for a dielectric layer which imparts excellent anti-caking properties to the dielectric layer can be provided.

Furthermore, according to the present invention, a dielectric layer formed by drying a coating film formed of the above-mentioned dielectric layer slurry composition can be provided.

Furthermore, according to the present invention, a capacitor formed using the above-mentioned dielectric layer can be provided.

10: Stacked ceramic capacitor 11: Dielectric 12: Internal electrode 13: External electrode

FIG. 1 is a schematic cross-sectional view showing an example of a stacked ceramic capacitor as the capacitor of the present invention.

without.

Claims (10)

A dielectric layer binder composition is provided, which comprises a polymer and a solvent, wherein the polymer contains a conjugated diene monomer unit and has a glass transition temperature of above -45°C. The adhesive composition for a dielectric layer as claimed in claim 1, wherein the glass transition temperature is below 20°C. The binder composition for a dielectric layer as claimed in claim 1, wherein the tetrahydrofuran-insoluble content of the polymer is 70% by mass or more. The binder composition for a dielectric layer as claimed in claim 1, wherein the polymer is a particulate polymer, and the average particle size of the particulate polymer is greater than or equal to 0.01 μm and less than or equal to 1.0 μm. The binder composition for a dielectric layer as described in claim 1, wherein the polymer further contains aromatic vinyl monomer units. The binder composition for a dielectric layer as described in claim 1, wherein the solvent is water or an aqueous solvent. The binder composition for a dielectric layer as claimed in any one of claims 1 to 6, wherein the content ratio of the covalent diene monomer units is 20 mass % or more and 60 mass % or less, when all the monomer units contained in the polymer are taken as 100 mass %. A slurry composition for a dielectric layer, comprising the binder composition for a dielectric layer as described in any one of claims 1 to 7 and a dielectric material. A dielectric layer is formed by drying a coating film made of the dielectric layer slurry composition described in claim 8. A capacitor is formed using the dielectric layer described in claim 9.

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