Composition for firing, green sheet, multilayer ceramic capacitor, and method for producing multilayer ceramic capacitor

Abstract

The present invention provides: a composition for firing from which a sheet having excellent strength and ductility can be obtained; and a green sheet which uses the composition for firing. This composition for firing comprises a copolymer (X), wherein: the copolymer (X) includes a structural unit derived from a radical polymerizable monomer (A) that has a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms and a structural unit derived from an alkyl (meth)acrylate (B) (excluding the radical polymerizable monomer (A)); 0.1-9 mass% of the structural unit derived from the radical polymerizable monomer (A) is contained with respect to the total mass of all structural units constituting the copolymer (X); and the structural unit derived from the alkyl (meth)acrylate (B) includes a structural unit derived from an alkyl (meth)acrylate (B2) which has a C9-30 alkyl group.

Description

Firing composition, green sheet, multilayer ceramic capacitor, and method for manufacturing multilayer ceramic capacitor

[0001] The present invention relates to a firing composition, a green sheet, a multilayer ceramic capacitor, and a method for manufacturing a multilayer ceramic capacitor. This application claims priority to Japanese Patent Application No. 2024-034424, filed on March 6, 2024, the contents of which are incorporated herein by reference.

[0002] A known method for manufacturing multilayer electronic components, such as multilayer ceramic capacitors, is to laminate, press, and sinter green sheets printed with internal electrodes. The green sheets are obtained by applying a slurry containing a binder, ceramic, and a solvent to a support and drying it. The green sheets are then sintered to form a ceramic compact.

[0003] Polyvinyl butyral is commonly used as a binder for producing green sheets. In recent years, green sheets using acrylic resins with good thermal decomposition properties instead of polyvinyl butyral have been proposed. For example, Patent Documents 1 and 2 disclose acrylic resins having structural units derived from alkyl (meth)acrylates with alkyl groups having 1 to 8 carbon atoms as binders for green sheets. Furthermore, Patent Documents 3 and 4 disclose acrylic resins having structural units derived from glycerol methacrylate.

[0004] Japanese Unexamined Patent Publication No. 5-9060 Japanese Unexamined Patent Publication No. 10-29870 Japanese Unexamined Patent Application No. 2000-248224 Japanese Unexamined Patent Application No. 2006-265362

[0005] However, acrylic resins are harder and more brittle than polyvinyl butyral. Therefore, sheets such as green sheets using acrylic resins as binders, as in Patent Documents 1 and 2, have poor strength and ductility. Therefore, acrylic resins having structural units derived from glycerol methacrylate, as in Patent Documents 3 and 4, have been proposed, but their strength and extensibility are still unsatisfactory. The present invention aims to provide a firing composition that can produce sheets with excellent strength and ductility, and a green sheet using the same.

[0006] As a result of extensive research, the inventors discovered that a sheet having excellent strength and ductility can be obtained by using a composition for firing containing a copolymer having a specific amount of structural units derived from a compound having a specific structure, and thus completed the present invention.

[0007] That is, the present invention has the following aspects: [1] A baking composition containing a copolymer (X), wherein the copolymer (X) comprises structural units derived from a radically polymerizable monomer (A) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and structural units derived from an alkyl(meth)acrylate (B) (excluding the radically polymerizable monomer (A)), the structural units derived from the radically polymerizable monomer (A) account for 0.1 to 9 mass% of the structural units based on the total mass of all structural units constituting the copolymer (X), and the structural units derived from the alkyl(meth)acrylate (B) comprise structural units derived from an alkyl(meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms. [2] The baking composition according to [1], wherein the structural units derived from the alkyl(meth)acrylate (B) further comprise structural units derived from an alkyl(meth)acrylate (B1) (excluding the alkyl(meth)acrylate (B2)) having an alkyl group having 1 to 8 carbon atoms. [3] The composition for firing according to [2], wherein the copolymer (X) contains 29.9 to 99.8 mass% of structural units derived from the alkyl (meth)acrylate (B1) having an alkyl group having 1 to 8 carbon atoms, based on the total mass of all structural units constituting the copolymer (X). [4] The composition for firing according to any of [1] to [3], wherein the copolymer (X) contains 0.1 to 70 mass% of structural units derived from the alkyl (meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms, based on the total mass of all structural units constituting the copolymer (X). [5] The composition for firing according to any of [1] to [4], wherein the glass transition temperature of the copolymer (X) is 5 to 100°C. [6] The composition for firing according to any of [1] to [5], further containing barium titanate or alumina. [7] The composition for firing according to any of [1] to [5], wherein the maximum stress in a tensile test when formed into a sheet is 2 N / mm ２[8] The composition for firing of any one of [1] to [7], which, when formed into a sheet, has a breaking strain of 0.5% or more in a tensile test. [9] A green sheet using the composition for firing of any one of [1] to [8].

[10] A multilayer ceramic capacitor including a laminated green sheet obtained by laminating the green sheets of [9].

[11] A method for producing a multilayer ceramic capacitor, comprising the steps of: laminating the green sheets of [9], pressing the laminated green sheets to form a green sheet laminate, and dicing the green sheet laminate.

[0008] According to the present invention, it is possible to provide a composition for firing that can give a sheet having excellent strength and ductility, and a green sheet using the same.

[0009] The present invention will be described in further detail below with reference to preferred embodiments of the invention. However, the following description is merely an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the invention. In this specification, the suffix "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits. In this specification, "(meth)acrylate" is a general term for acrylate and methacrylate. "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid. "(meth)acrylonitrile" is a general term for acrylonitrile and methacrylonitrile. In this specification, the term "sheet" conceptually encompasses sheet, film, and tape. Furthermore, a sheet formed from the baking composition of the present invention is simply referred to as a "sheet."

[0010] [Composition for baking] One embodiment of the composition for baking of the present invention will be described below. The composition for baking of this embodiment contains the copolymer (X) shown below. The composition for baking may consist solely of the copolymer (X), or may further contain components other than the copolymer (X) (hereinafter also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired.

[0011] <Copolymer (X)> The copolymer (X) is a copolymer containing a structural unit (hereinafter also referred to as "structural unit (a)") derived from a radical polymerizable monomer (A) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and a structural unit (hereinafter also referred to as "structural unit (b)") derived from an alkyl(meth)acrylate (B) (excluding the radical polymerizable monomer (A)). As will be described in detail later, the structural unit (b) contains a structural unit derived from an alkyl(meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms. The copolymer (X) may further contain a structural unit (hereinafter also referred to as "structural unit (c)") derived from a monomer (C) other than the radical polymerizable monomer (A) and the alkyl(meth)acrylate (B).

[0012] (Radical Polymerizable Monomer (A)) The radical polymerizable monomer (A) (hereinafter also referred to as "monomer (A)") is a radical polymerizable monomer having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms. Examples of the monomer (A) include a monomer (A1) represented by the following general formula (1) and a monomer (A2) represented by the following general formula (2), which can improve the strength and ductility of the sheet. The monomer (A) may be used alone or in combination of two or more types. That is, the copolymer (X) may contain one type of structural unit (a) or two or more types of structural unit (a). In the present invention, the structural unit derived from the monomer (A1) is also referred to as a "structural unit (a1)," and the structural unit derived from the monomer (A2) is also referred to as a "structural unit (a2)."

[0013]

[0014] In formula (1), R １ is a hydrogen atom or a methyl group, and R ２ ~R ４ are each independently a hydrogen atom or a hydroxyl group, and x is an integer of 0 to 3.

[0015]

[0016] In formula (2), R ５ is a hydrogen atom or a methyl group, and R ６is —NH— or an oxygen atom, and R ７ is an alkylene group having 1 to 5 carbon atoms or an alkylene group having 1 to 5 carbon atoms and a hydroxyl group, and R ８ is a hydrogen atom or a hydroxyl group, y is an integer of 0 to 1, and z is an integer of 0 to 1.

[0017] R in formula (2) ７ Examples of the alkyl group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hydroxymethylene group, a 1-hydroxyethylene group, a 2-hydroxypropylene group, a 2-hydroxybutylene group, a 3-hydroxybutylene group, a 2-hydroxypentylene group, and a 3-hydroxypentylene group.

[0018] Examples of the monomer (A) include glycerin monoacrylate (in formula (1), R １ is a hydrogen atom, and R ２ ~R ４ is a hydrogen atom and x is 1), glycerin monomethacrylate (a compound in which R １ is a methyl group, and R ２ ~R ４ is a hydrogen atom and x is 1), dopamine acrylamide (in formula (2), R ５ is a hydrogen atom, and R ６ is —NH—, and R ７ is an ethylene group, and R ８ is a hydrogen atom, y is 1, and z is 0.), dopamine methacrylamide (in formula (2), R ５ is a methyl group, and R ６ is —NH—, and R ７ is an ethylene group, and R ８is a hydrogen atom, y is 1, and z is 0. ), a monomer (A21) represented by the following formula (21), a monomer (A22) represented by the following formula (22), a monomer (A23) represented by the following formula (23), and a monomer (A24) represented by the following formula (24). In the present invention, a structural unit derived from monomer (A21) is also referred to as "structural unit (a21)," a structural unit derived from monomer (A22) is also referred to as "structural unit (a22)," a structural unit derived from monomer (A23) is also referred to as "structural unit (a23)," and a structural unit derived from monomer (A24) is also referred to as "structural unit (a24)."

[0019]

[0020] As the monomer (A), the monomer (A1) is preferred, and in particular, R １ is a methyl group and x is 0 or 1, and １ is a methyl group and x is 1, and １ is a methyl group, and R ２ ~R ４ Particularly preferred are compounds in which is a hydrogen atom and x is 1.

[0021] (Alkyl(meth)acrylate (B)) The alkyl(meth)acrylate (B) (hereinafter also referred to as "monomer (B)") is a monomer having an alkyl group having one or more carbon atoms (excluding monomer (A)). Examples of the monomer (B) include alkyl(meth)acrylate (B1) having an alkyl group having 1 to 8 carbon atoms (excluding alkyl(meth)acrylate (B2) described below; hereinafter also referred to as "monomer (B1)"), alkyl(meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms (hereinafter also referred to as "monomer (B2)"), and alkyl(meth)acrylate (B3) having an alkyl group having more than 30 carbon atoms (excluding monomer (B1) and monomer (B2); hereinafter also referred to as "monomer (B3)"). The copolymer (X) contains a structural unit derived from monomer (B2) (hereinafter also referred to as "structural unit (b2)"). Copolymer (X) preferably contains a structural unit derived from monomer (B1) (hereinafter also referred to as "structural unit (b1)"). In the present invention, the structural unit derived from monomer (B3) is also referred to as "structural unit (b3)".

[0022] <<Monomer (B1)>> Examples of the monomer (B1) include alkyl(meth)acrylates having a linear or branched hydrocarbon skeleton, such as methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, i-propyl(meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, t-butyl(meth)acrylate, n-pentyl(meth)acrylate, i-pentyl(meth)acrylate, n-hexyl(meth)acrylate, heptyl(meth)acrylate, n-octyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate; Examples of the monomer (B1) include alkyl (meth)acrylates having an alicyclic skeleton such as i-butyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; and aminoalkyl (meth)acrylacrylates such as N-dimethylaminoethyl (meth)acrylate and N-diethylaminoethyl (meth)acrylate. Methyl methacrylate is more preferred as the monomer (B1). Furthermore, in terms of further improving the strength, ductility, and thermal decomposition properties of the sheet, alkyl methacrylates are preferred, and i-butyl methacrylate is more preferred. The monomer (B1) may be used alone or in combination of two or more types. That is, the copolymer (X) may contain one type of structural unit (b1), or may contain two or more types of structural units (b1). In particular, from the viewpoint of easily adjusting the balance between hardness and flexibility, it is preferable to use two or more types of monomer (B1) in combination. That is, it is preferable that the copolymer (X) contains two or more types of structural units (b1).

[0023] <<Monomer (B2)>> Examples of the monomer (B2) include alkyl (meth)acrylates having a linear or branched hydrocarbon skeleton, such as nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate. Preferred monomers (B2) are lauryl (meth)acrylate and stearyl (meth)acrylate, with methacrylates having a linear alkyl chain, such as stearyl methacrylate, being more preferred. Furthermore, alkyl methacrylates are preferred in terms of improving the thermal decomposition properties of the sheet. The monomer (B2) may be used alone or in combination of two or more. That is, the copolymer (X) may contain one type of structural unit (b2), or may contain two or more types of structural units (b2).

[0024] <<Monomer (B3)>> Examples of the monomer (B3) include hentriacontyl (meth)acrylate, dotriacontyl (meth)acrylate, tritriacontyl (meth)acrylate, tetratriacontyl (meth)acrylate, pentatriacontyl (meth)acrylate, hexatriacontyl (meth)acrylate, and tetracontyl (meth)acrylate. The monomer (B3) may be used alone or in combination of two or more. That is, the copolymer (X) may contain one type of structural unit (b3), or may contain two or more types of structural unit (b3).

[0025] (Monomer (C)) The monomer (C) is not particularly limited as long as it is copolymerizable with the monomer (A) and the monomer (B), and examples thereof include monomers having a carboxyl group such as (meth)acrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid; (meth)acrylonitrile; and aromatic vinyl monomers such as styrene, α-methylstyrene, divinylbenzene, and vinyltoluene. The monomer (C) may be used alone or in combination of two or more types. That is, the copolymer (X) may contain one type of structural unit (c), or may contain two or more types of structural unit (c).

[0026] (Ratio) The ratio of the structural unit (a) in copolymer (X) is 0.1 to 9% by mass, based on the total mass of all structural units constituting copolymer (X). It may be 0.5% by mass or more, 0.8% by mass or more, or 1% by mass or more. It may be 8% by mass or less, 7% by mass or less, or 6% by mass or less. The above upper and lower limits can be arbitrarily combined. For example, it may be 0.5 to 8% by mass, 0.8 to 7% by mass, or 1 to 6% by mass. When the ratio of the structural unit (a) is equal to or greater than the lower limit, the ductility and strength of the sheet are further increased. When the ratio of the structural unit (a) is equal to or less than the upper limit, the strength of the sheet is further increased.

[0027] The proportion of the structural unit (b) in copolymer (X), relative to the total mass of all structural units constituting copolymer (X), may be 50% by mass or more, 70% by mass or more, 80% by mass or more, or 91% by mass or more. It may also be 99.9% by mass or less, 99.5% by mass or less, 99.2% by mass or less, or 99% by mass or less. The above upper and lower limits can be arbitrarily combined. For example, it may be 50 to 99.9% by mass, 70 to 99.5% by mass, 80 to 99.2% by mass, or 91 to 99% by mass. When the proportion of the structural unit (b) is equal to or greater than the lower limit, the strength and thermal decomposition property of the sheet are improved. When the proportion of the structural unit (b) is equal to or less than the upper limit, the ductility of the sheet is further improved.

[0028] The proportion of the structural unit (b1) in the structural unit (b) is preferably 29.9 to 99.8 mass% relative to the total mass of all structural units constituting the copolymer (X), more preferably 40 to 95 mass%, even more preferably 50 to 90 mass%, and particularly preferably 60 to 85 mass%. When the proportion of the structural unit (b1) is equal to or greater than the lower limit, the strength of the sheet is further increased. When the proportion of the structural unit (b1) is equal to or less than the upper limit, the ductility of the sheet is further increased.

[0029] The proportion of the structural unit (b2) in the structural unit (b) is preferably 0.1 to 70 mass%, more preferably 5 to 60 mass%, and even more preferably 10 to 60 mass%, based on the total mass of all structural units constituting the copolymer (X). When the proportion of the structural unit (b2) is equal to or greater than the lower limit, the ductility of the sheet is further increased. When the proportion of the structural unit (b2) is equal to or less than the upper limit, the strength of the sheet is further increased.

[0030] The proportion of the structural unit (c) in the copolymer (X) is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on the total mass of all structural units constituting the copolymer (X). The copolymer (X) does not necessarily need to contain the structural unit (c).

[0031] From the viewpoint of improving thermal decomposition properties, copolymer (X) preferably contains a structural unit derived from methacrylate (hereinafter also referred to as "structural unit (m)"). The proportion of structural unit (m) in copolymer (X) is preferably 50 to 100 mass% relative to the total mass of all structural units constituting copolymer (X), more preferably 65 to 100 mass%, even more preferably 80 to 99.9 mass%, and particularly preferably 95 to 99.5 mass%. When the proportion of structural unit (m) is equal to or greater than the lower limit, thermal decomposition properties are improved. When the proportion of structural unit (m) is equal to or less than the upper limit, flexibility can be designed over a wide range. The total proportion of all structural units constituting copolymer (X) is 100 mass%.

[0032] The content of the structural unit (b2) in the copolymer (X) relative to 100 parts by mass of the structural unit (a) in the copolymer (X) may be 40 parts by mass or more, 100 parts by mass or more, 550 parts by mass or more, 600 parts by mass or more, or 700 parts by mass or more. It may also be 10,000 parts by mass or less, 9,000 parts by mass or less, 5,000 parts by mass or less, 3,000 parts by mass or less, or 2,000 parts by mass. The above upper and lower limits can be arbitrarily combined. For example, it may be 40 to 10,000 parts by mass, 100 to 9,000 parts by mass, 550 to 10,000 parts by mass, 550 to 5,000 parts by mass, 600 to 3,000 parts by mass, or 700 to 2,000 parts by mass.

[0033] In the present invention, the following baking composition (S) may be used as the baking composition: A baking composition (S) containing a copolymer (X), wherein the copolymer (X) comprises a structural unit derived from a radically polymerizable monomer (A) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and a structural unit derived from an alkyl(meth)acrylate (B) (excluding the radically polymerizable monomer (A)), the structural unit derived from the alkyl(meth)acrylate (B) comprises a structural unit (b2) derived from an alkyl(meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms, and the content of the structural unit derived from the alkyl(meth)acrylate (B2) in the copolymer (X) is 550 to 10,000 parts by mass per 100 parts by mass of the structural unit derived from the radically polymerizable monomer (A) in the copolymer (X).

[0034] (Physical Properties) The glass transition temperature (Tg) of copolymer (X) is preferably 5 to 100°C, more preferably 20 to 80°C, and even more preferably 45 to 70°C. When the glass transition temperature of copolymer (X) is equal to or higher than the lower limit, deformation of molded products such as sheets is suppressed. When the glass transition temperature of copolymer (X) is equal to or lower than the upper limit, adhesion is improved when laminated by thermocompression bonding of molded products such as sheets. The glass transition temperature of copolymer (X) is a value calculated by Fox's calculation formula, represented by the following formula (I), from the glass transition temperatures and mass fractions of the homopolymers of each monomer constituting copolymer (X). 1 / (273+Tg)=Σ(Wi / (273+Tgi)) (I) (In formula (I), Wi represents the mass fraction of monomer i, and Tgi represents the glass transition temperature (°C) of a homopolymer of monomer i.) The glass transition temperature of a homopolymer of monomer i can be the value described in the Polymer Handbook [Polymer Handbook, J. Brandrup, Interscience, 1989]. When a monomer whose homopolymer glass transition temperature is not described in the Polymer Handbook is used, the Tg used is an actual value measured by the method described in JIS K 7121:2012 "Method for measuring transition temperatures of plastics."

[0035] The weight-average molecular weight (Mw) of copolymer (X) is preferably 50,000 to 400,000, more preferably 150,000 to 380,000, and even more preferably 180,000 to 350,000. When the weight-average molecular weight of copolymer (X) is equal to or greater than the lower limit, the ductility of the sheet is further improved. When the weight-average molecular weight of copolymer (X) is equal to or less than the upper limit, the handleability of the firing composition and the slurry described below is improved. The weight-average molecular weight of copolymer (X) is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene. Detailed measurement conditions are as described in the Examples section below.

[0036] (Method for Producing Copolymer (X)) Copolymer (X) can be obtained by polymerizing a monomer mixture containing monomer (A) and monomer (B) in the presence of a polymerization initiator by a commonly known polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization. For the production of copolymer (X), solution polymerization is preferred from the viewpoints of ease of molecular weight control and the possibility of using monomers containing various functional groups. The monomer mixture may further contain monomer (C) as necessary.

[0037] Examples of the polymerization initiator include ordinary radical polymerization initiators such as organic peroxides, azo compounds, etc. The organic peroxide is not particularly limited, and examples thereof include t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butylperoxy-2-ethylhexanoate, and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate. The azo compound is not particularly limited, and examples thereof include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile). One type of polymerization initiator may be used alone, or two or more types may be used in combination. The amount of polymerization initiator added is not particularly limited, and from the viewpoint of improving the polymerization rate and adjusting the molecular weight, 0.1 to 5 parts by mass per 100 parts by mass of the monomer mixture is preferred.

[0038] A chain transfer agent may be used when polymerizing the monomer mixture. Examples of the chain transfer agent include mercaptans, α-methylstyrene dimer, and terpenoids. When a chain transfer agent is used in the polymerization of the monomer mixture in the present invention, it is preferable to use mercaptans. The chain transfer agent may be used alone or in combination of two or more. The amount of the chain transfer agent to be added is not particularly limited, and from the viewpoint of easily adjusting the molecular weight of the copolymer (X), it is preferably 0.1 to 1 part by mass per 100 parts by mass of the monomer mixture.

[0039] Examples of the solvent (reaction solvent) used in solution polymerization of the monomer mixture include alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and t-butyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbon-based solvents such as toluene and xylene; and ester-based solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. One type of solvent may be used alone, or two or more types may be used in combination.

[0040] Examples of emulsifiers used in emulsion polymerization of the monomer mixture include anionic emulsifiers such as sodium dodecylbenzenesulfonate, sodium lauryl sulfonate, sodium lauryl sulfate, dipotassium alkenyl succinate, and sodium dialkyl sulfosuccinate; anionic emulsifiers having a polyoxyethylene group; nonionic emulsifiers such as polyoxyethylene nonylphenyl ether and polyoxyethylene lauryl ether; and reactive emulsifiers having a polymerizable double bond in the molecule. One type of emulsifier may be used alone, or two or more types may be used in combination. The amount of emulsifier added is not particularly limited, and from the viewpoints of thermal decomposition property and polymerization stability, 0.5 to 3 parts by mass per 100 parts by mass of the monomer mixture is preferred.

[0041] When copolymer (X) is produced by solution polymerization, copolymer (X) is obtained in a state dissolved in a solvent (reaction solvent), i.e., in the state of a polymer solution. The obtained polymer solution may be used as a composition for firing. In this case, the composition for firing contains copolymer (X) and, as an optional component, a solvent. A filler may be added to the obtained polymer solution, and the solution may be further diluted with a solvent as necessary to be used as a slurry. The solvent used for dilution may be the reaction solvent used in the production of copolymer (X). The slurry will be described later.

[0042] <Content> The content of copolymer (X) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and particularly preferably 30% by mass or more, relative to the total mass of the composition for baking. When the content of copolymer (X) is equal to or greater than the above-mentioned lower limit, the drying properties of the sheet are good. When the content of copolymer (X) is equal to or greater than 70% by mass, more preferably equal to or less than 55% by mass, even more preferably equal to or less than 50% by mass, and particularly preferably equal to or less than 46% by mass, relative to the total mass of the composition for baking. When the content of copolymer (X) is equal to or less than the above-mentioned upper limit, the composition is easily formed into a sheet. The above-mentioned upper and lower limits of the content of copolymer (X) can be arbitrarily combined. For example, the content of copolymer (X) is preferably 10 to 70% by mass, more preferably 20 to 55% by mass, even more preferably 25 to 50% by mass, and particularly preferably 30 to 46% by mass, relative to the total mass of the composition for baking.

[0043] <Physical properties> The composition for firing has a maximum stress of 2 N / mm in a tensile test when formed into a sheet. ２ It is preferable that the resistance is 10 N / mm or more, and more preferably 10 N / mm ２ More preferably, it is 15 N / mm ２ If the maximum stress is equal to or greater than the lower limit, sufficient strength can be achieved. From the viewpoint of the strength of the sheet, the greater the maximum stress, the better. There is no particular upper limit to the maximum stress, and it is usually 100 N / mm ２ The following is the result.

[0044] The composition for firing preferably has a breaking strain of 0.5% or more in a tensile test when formed into a sheet, more preferably 1.0% or more, and even more preferably 1.5% or more. If the maximum stress is equal to or greater than the lower limit, sufficient ductility can be exhibited. From the viewpoint of sheet ductility, a larger breaking strain is preferable, and the upper limit of the breaking strain is not particularly limited and is usually 100% or less.

[0045] The maximum stress and breaking strain of the sheet were measured by a tensile test. The tensile test was performed using an autograph in accordance with JIS K 7127:1999 (ISO 527-3:1995) under conditions of an initial chuck distance of 30 mm, a tensile speed of 50 mm / min, and a temperature of 23°C. Detailed measurement conditions are as described in the examples below, and the sheets were produced as in the green sheets of the examples.

[0046] <Effects> The composition for baking of the present embodiment described above contains a copolymer (X) including the structural unit (a) and the structural unit (b). The monomer (A) from which the structural unit (a) is derived is a radically polymerizable monomer having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms. When the copolymer (X) contains the structural unit (a) derived from this monomer (A), strong interactions due to multiple hydrogen bonds are expressed, which improves the hardness and brittleness when the composition for baking is formed into a sheet, resulting in a sheet with excellent strength and ductility.

[0047] The firing composition of this embodiment can be used as a binder for binding fillers. It is particularly suitable as a binder for green sheets used in semiconductor manufacturing. For example, the firing composition of this embodiment, a filler, and, if necessary, a solvent are mixed to form a slurry, which is then formed into a sheet and fired to obtain the green sheet of the present invention described below.

[0048] [Slurry] One embodiment of the slurry will be described below. The slurry of this embodiment contains the above-mentioned composition for firing of the present invention and a filler. When the composition for firing of the present invention does not contain a solvent, the slurry further contains a solvent in addition to the composition for firing and the filler. The slurry may further contain additives other than the filler and the solvent as necessary.

[0049] When a sheet obtained by molding the slurry is used as a green sheet for semiconductor manufacturing, for example, barium titanate powder, lead complex perovskite powder, or strontium titanate powder is used as the filler. Barium titanate powder is BaTiO ３ The ceramic powder may include BaTiO ３ Examples of the BaTiO based ceramic powder include ３ , BaTiO ３ For example, Ca (calcium) and Zr (zirconium) are partially dissolved in the １－ｘ Ca ｘ ) TiO ３ , Ba(Ti １－ｙ Ca ｙ ) O ３ , (Ba １－ｘ Ca ｘ ) (Ti １－ｙ Zr ｙ ) O ３ , or Ba(Ti １－ｙ Zr ｙ ) O ３ The filler may be used alone or in combination of two or more kinds.

[0050] Examples of the solvent include the reaction solvent used in the production of copolymer (X). In particular, aromatic hydrocarbon solvents and alcohol solvents are preferred, and toluene and ethanol are more preferred. The solvent may be used alone or in combination of two or more.

[0051] Examples of additives include oxides of magnesium, manganese, vanadium, chromium, and europium; oxides of cobalt, nickel, lithium, boron, sodium, potassium, and silicon; oxides of rare earth elements other than europium (scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, Yb, and lutetium); glass; and plasticizers such as diisononyl phthalate, diisodecyl phthalate, and butylbenzyl phthalate. One type of additive may be used alone, or two or more types may be used in combination.

[0052] The content of copolymer (X) is preferably 3 to 20% by mass, more preferably 4 to 15% by mass, and even more preferably 5 to 10% by mass, relative to the total mass of the slurry. The content of filler is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, and even more preferably 60 to 75% by mass, relative to the total mass of the slurry. The content of solvent is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 20 to 30% by mass, relative to the total mass of the slurry. The content of additives is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1 to 3% by mass, relative to the total mass of the slurry. The total content of all components contained in the slurry is 100% by mass.

[0053] The slurry of this embodiment is suitable as a slurry for producing a green sheet when manufacturing a semiconductor.

[0054] [Green Sheet] Hereinafter, one embodiment of the green sheet will be described. The green sheet of this embodiment (also referred to as a "ceramic green sheet" or "dielectric sheet") is a green sheet using the above-mentioned composition for firing of the present invention, and contains, for example, the copolymer (X) contained in the composition for firing, a filler, and, if necessary, an additive. Examples of the filler and additive include the fillers and additives exemplified above in the description of the slurry.

[0055] A green sheet (dielectric sheet) is obtained by coating the above-described slurry onto a release film, such as polyester, and drying it. Electrodes are printed on the green sheet by screen printing or other methods to form internal electrodes. After drying, the printed green sheet is peeled off from the release film. Such green sheets are stacked (lamination process), and the stacked green sheets are compressed and integrated by applying pressure and heat (thermocompression bonding process), after which they are cut into individual chips (dicing process). The internal electrodes and dielectric layers are then sintered in a firing furnace to produce a multilayer ceramic capacitor.

[0056] The content of copolymer (X) is preferably 1 to 30 mass% relative to the total mass of the green sheet, more preferably 3 to 20 mass%, and even more preferably 5 to 15 mass%. The content of filler is preferably 70 to 99 mass%, more preferably 80 to 97 mass%, and even more preferably 85 to 95 mass% relative to the total mass of the green sheet. The content of additive compound is preferably 0.1 to 10 mass%, more preferably 0.5 to 5 mass%, and even more preferably 1 to 3 mass% relative to the total mass of the green sheet. The total content of all components contained in the green sheet is 100 mass%.

[0057] The thickness of the green sheet is not particularly limited, and is preferably 0.1 to 100 μm, more preferably 0.1 to 80 μm, and even more preferably 0.1 to 50 μm.

[0058] The green sheet of the present embodiment is a green sheet using the composition for firing of the present invention, specifically, a green sheet obtained by firing the composition for firing of the present invention, and therefore has excellent strength and ductility, and is useful as an electronic component used in semiconductor manufacturing, for example, a multilayer ceramic capacitor.

[0059] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In addition, "parts" and "%" respectively mean "parts by mass" and "% by mass" unless otherwise specified.

[0060] [Measurement and Evaluation] <Calculation of Glass Transition Temperature (Tg)> The glass transition temperature of copolymer (X) was calculated by Fox's calculation formula represented by the following formula (I): 1 / (273+Tg)=Σ(Wi / (273+Tgi)) (I) (In formula (I), Wi represents the mass fraction of monomer i, and Tgi represents the glass transition temperature (°C) of a homopolymer of monomer i.)

[0061] <Measurement of Weight-Average Molecular Weight (Mw)> The weight-average molecular weight (Mw) of the copolymer (X) was measured by gel permeation chromatography (GPC) and calculated as a polystyrene-equivalent value using a calibration curve of standard polystyrene. The GPC measurement conditions were as follows. (GPC Measurement Conditions) Apparatus: Tosoh Corporation, product name "HLC-8220GPC". Column: Tosoh Corporation, product name "TSKgel G5000HXL (7.8 mmφ×300 mm)" and product name "GMHXL-L (7.8 mmφ×300 mm)" connected in series. Eluent: Tetrahydrofuran. Sample concentration: 0.4% by mass. Measurement temperature: 40°C. Injection volume: 100 μL. Flow rate: 1.0 mL / min. Detector: RI (built-in), UV (Tosoh Corporation, product name "UV-8220").

[0062] <Tensile Test> The sheet was subjected to a tensile test using an autograph (manufactured by Shimadzu Corporation, product name "AGX-10kNVD") in accordance with JIS K 7127:1999 (ISO 527-3:1995) under the conditions of an initial chuck distance of 30 mm, a tensile speed of 50 mm / min, a sheet film thickness of 30 μm±10 μm, and a temperature of 23 ° C. The highest stress in the stress-strain curve at that time was taken as the maximum stress. In addition, the area under the curve was calculated from the obtained stress-strain curve (SS curve) to determine the breaking strain. Furthermore, based on the measurement results of the maximum stress and breaking strain, the sheet was evaluated according to the following evaluation criteria.

[0063] (Strength: Evaluation criteria for maximum stress) A: Maximum stress is 15 N / mm ２ B: Maximum stress is 2 N / mm or more. ２ Above, 15N / mm ２ C: Maximum stress is less than 2 N / mm ２is less than or the maximum stress cannot be measured.

[0064] (Ductility: Evaluation criteria for fracture strain) A: The fracture strain is 1.5% or more. B: The fracture strain is 0.5% or more and less than 1.5%. C: The fracture strain is less than 0.5%, or the maximum stress cannot be measured.

[0065] Example 1 Production of Copolymer (X1) A reaction vessel equipped with a thermometer, temperature regulator, stirrer, reflux condenser, nitrogen gas inlet tube, and dropping device was charged with 75 parts of toluene, 5 parts of isopropyl alcohol, 1 part of glycerin monomethacrylate (manufactured by NOF Corporation, trade name "Blemmer GLM-EX"), 82.5 parts of methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "MMA"), 16.0 parts of a mixture of an alkyl methacrylate having 12 carbon atoms in the alkyl group and an alkyl methacrylate having 13 carbon atoms in the alkyl group (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester SL"), 0.5 parts of 2-hydroxyethyl acrylate, and 0.05 parts of t-butylperoxy-2-ethylhexanoate. The atmosphere inside the polymerization vessel was thoroughly purged with nitrogen, and the temperature was raised to 80°C in 45 minutes and to 90°C in 30 minutes. After aging for 60 minutes, a mixture of 40 parts toluene and 0.2 parts t-butylperoxy-2-ethylhexanoate was added dropwise to the reaction vessel over 150 minutes. After completion of the addition, 3 parts toluene was rapidly added dropwise, followed by aging for 60 minutes. Subsequently, a mixture of 12 parts toluene and 1.5 parts 2,2'-azobis(2-methylbutyronitrile) was added dropwise over 30 minutes, followed by aging for 90 minutes. After cooling, 28 parts isopropyl alcohol was added to obtain a polymer solution containing the acrylic polymer copolymer (X1) as a binder component. The content of copolymer (X1) relative to the total mass of the polymer solution was 38%. The glass transition temperature of the obtained copolymer (X1) was calculated, and the weight-average molecular weight was measured. The results are shown in Table 1. When measuring the weight-average molecular weight of copolymer (X1), the solvent was removed from the polymer solution and the dried product was used for the measurement.

[0066] <Preparation of Slurry> A glass bottle (capacity: 225 cm ３), 2 parts of the polymer solution obtained previously as a binder component (5.26 parts as polymer solution), 20 parts of barium titanate (manufactured by Kyoritsu Material Co., Ltd., product name "BT-HP400"), 0.4 parts of diisononyl phthalate, 5.6 parts of toluene, and 1.7 parts of isopropyl alcohol were added, and the mixture was dispersed using a rocking shaker (manufactured by Seiwa Giken Co., Ltd., product name "RS-05W") to obtain a slurry.

[0067] <Production of Green Sheet> The slurry obtained above was applied to a release film using an applicator, and the coating was dried at room temperature (23°C) for 30 minutes. Thereafter, the coating was peeled off from the release film and further dried at 90°C for 15 minutes to produce a green sheet having a thickness of 30 μm±5 μm. Specifically, in Example 1, a green sheet having a thickness of 35 μm was obtained. The maximum stress and breaking strain of the obtained green sheet were measured. The results are shown in Table 2.

[0068] [Examples 2 to 6, Comparative Examples 1 to 3] Copolymers (X2) to (X9) were produced in the same manner as in Example 1, except that a monomer mixture having the formulation shown in Table 1 was used, and the glass transition temperatures were calculated and the weight-average molecular weights were measured. The results are shown in Table 1. Furthermore, slurries were produced in the same manner as in Example 1, except that a polymer solution containing any of the obtained copolymers (X2) to (X9) was used, and green sheets were produced using the resulting slurries, and the maximum stress and breaking strain were measured. The results are shown in Table 2. In Example 2, a sheet having a thickness of 26 μm was produced, in Example 3, a sheet having a thickness of 33 μm, in Example 4, a sheet having a thickness of 30 μm, and in Comparative Examples 1 and 2, attempts were made to produce sheets having a thickness of 35 μm.

[0069]

[0070] The abbreviations in Table 1 have the following meanings. A blank space in Table 1 means that the component is not blended (amount blended: 0 parts by mass). [Monomer (A)] GLM: Glycerin monomethacrylate (manufactured by NOF Corporation, trade name "BLEMMER GLM-EX"; R in formula (1) １ is a methyl group, and R ２ ~R ４is a hydrogen atom and x is 1, homopolymer Tg: 55°C). Monomer A22: 2-(methacryloyloxy)ethyl 3,4,5-trihydroxybenzoate. [Monomer (B)] MMA: methyl methacrylate (homopolymer Tg: 105°C). iBMA: i-butyl methacrylate (homopolymer Tg: 48°C). HEMA: 2-hydroxyethyl methacrylate (homopolymer Tg: 55°C). HEA: 2-hydroxyethyl acrylate (homopolymer Tg: -20°C). SLMA: a mixture of an alkyl methacrylate having 12 carbon atoms in the alkyl group and an alkyl methacrylate having 13 carbon atoms in the alkyl group (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester SL", homopolymer Tg: -65°C). SMA: stearyl methacrylate, homopolymer Tg: 38°C). [Initiator] AMBN: 2,2'-azobis(2-methylbutyronitrile) Perbutyl O: t-butylperoxy-2-ethylhexanoate [Solvent] IPA: isopropyl alcohol.

[0071]

[0072] The abbreviations in Table 2 have the following meanings. Furthermore, blank spaces in Table 2 indicate that the component is not blended (amount blended: 0 parts by mass). BaTiO ３ : Barium titanate (manufactured by Kyoritsu Material Co., Ltd., product name "BT-HP400") DINP: Diisononyl phthalate IPA: Isopropyl alcohol

[0073] As is clear from Table 2, the green sheets obtained in each Example had high strength and excellent ductility. On the other hand, the green sheets obtained in Comparative Examples 1, 2, and 3, which did not use monomer (A), could not be formed into sheets, and therefore the maximum stress and breaking strain could not be measured.

[0074] The green sheet obtained from the firing composition of the present invention has high strength and excellent ductility, and is therefore useful as a green sheet used in the production of electronic components used in semiconductor manufacturing, such as multilayer ceramic capacitors, and is particularly suitable as a ceramic green sheet used in automotive multilayer ceramic capacitors.

Claims

1. A baking composition containing a copolymer (X), wherein the copolymer (X) comprises structural units derived from a radically polymerizable monomer (A) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and structural units derived from an alkyl(meth)acrylate (B) (excluding the radically polymerizable monomer (A)), wherein the structural units derived from the radically polymerizable monomer (A) account for 0.1 to 9 mass% of the structural units based on the total mass of all structural units constituting the copolymer (X), and the structural units derived from the alkyl(meth)acrylate (B) comprise structural units derived from an alkyl(meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms.

2. The baking composition according to claim 1, wherein the structural units derived from the alkyl(meth)acrylate (B) further include a structural unit derived from an alkyl(meth)acrylate (B1) having an alkyl group having 1 to 8 carbon atoms (excluding the alkyl(meth)acrylate (B2)).

3. The baking composition according to claim 2, wherein the copolymer (X) contains 29.9 to 99.8 mass% of structural units derived from the alkyl (meth)acrylate (B1) having an alkyl group having 1 to 8 carbon atoms, based on the total mass of all structural units constituting the copolymer (X).

4. The baking composition according to claim 1, wherein the copolymer (X) contains 0.1 to 70 mass% of structural units derived from the alkyl (meth)acrylate (B2) having an alkyl group having 9 to 30 carbon atoms, relative to the total mass of all structural units constituting the copolymer (X).

5. The composition for baking according to claim 1, wherein the glass transition temperature of the copolymer (X) is 5 to 100°C.

6. The firing composition according to claim 1, further comprising barium titanate or alumina.

7. When molded into a sheet, the maximum stress in the tensile test is 2N / mm ２ The baking composition according to claim 1 .

8. The composition for firing according to claim 1, which when formed into a sheet has a breaking strain of 0.5% or more in a tensile test.

9. A green sheet using the composition for firing according to any one of claims 1 to 8.

10. A multilayer ceramic capacitor comprising a laminated green sheet obtained by laminating the green sheets according to claim 9.

11. A method for manufacturing a multilayer ceramic capacitor, comprising the steps of: laminating the green sheets according to claim 9; compressing the laminated green sheets to form a green sheet laminate; and dicing the green sheet laminate.