JP2022009610A - Binder for producing ceramic green sheet, slurry composition, ceramic green sheet, and method for producing multilayer ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for producing a ceramic green sheet, from which a ceramic green sheet having high strength and an excellent pyrolytic property can be obtained while keeping the viscosity of a slurry composition low.

SOLUTION: A binder for producing a ceramic green sheet comprises a block copolymer which mainly contains a structural unit derived from a vinyl monomer, does not substantially have a polyvinyl acetal structure, and has hydrogen bonding functional groups. A slurry composition comprises: the binder for producing a ceramic green sheet which comprises a block copolymer which mainly contains a structural unit derived from a vinyl monomer, does not substantially have a polyvinyl acetal structure, and has hydrogen bonding functional groups; and ceramic powder. A ceramic green sheet is formed by using the slurry composition.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2020-08827 filed on May 20, 2020, the contents of which are incorporated herein by reference.

The present disclosure relates to a binder for producing a ceramic green sheet, a slurry composition, a method for producing a ceramic green sheet, and a method for producing a laminated ceramic capacitor.

Multilayer ceramic capacitors are generally manufactured by laminating ceramic green sheets formed with a slurry composition containing ceramic powder and a binder. In order to manufacture a laminated ceramic capacitor, first, a metal paste to be an internal electrode is printed on a ceramic green sheet, then the green sheet is laminated, and the laminated body is manufactured by heat-pressing. Subsequently, the binder resin contained in the laminate is thermally decomposed by subjecting the laminate to a heat treatment (defatting treatment), and then sintered at a high temperature. An external electrode is formed on the ceramic sintered body thus obtained, and a monolithic ceramic capacitor is obtained.

As a binder for the ceramic green sheet, a polyvinyl acetal resin or a (meth) acrylic resin is generally used (see, for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses a slurry composition for a ceramic green sheet containing a polyvinyl acetal resin having a specific composition as a binder. Further, Patent Document 2 discloses a slurry composition for a ceramic green sheet containing a (meth) acrylic resin having a specific composition as a binder.

Japanese Unexamined Patent Publication No. 2006-089354 International Publication No. 2018/235907

When a polyvinyl acetal resin is used as the binder, a ceramic green sheet having a relatively high strength can be obtained, but the polyvinyl acetal resin cannot be said to have sufficiently high pyrolysis property, and a binder residue may be generated after the degreasing treatment. I am concerned.

On the other hand, although the (meth) acrylic resin exhibits good thermal decomposability, it cannot be said that the strength of the obtained ceramic green sheet is sufficiently high. Therefore, there is a concern that the ceramic green sheet may be cracked or the like due to the load acting on the ceramic green sheet in the manufacturing process of the monolithic ceramic capacitor. Such cracking of the ceramic green sheet is more likely to occur as the performance of the electronic device is improved and the ceramic green sheet is made thinner and more laminated.

As a method of increasing the strength of the ceramic green sheet, it is conceivable to increase the molecular weight of the binder. However, when a high molecular weight binder is used, there is a concern that the slurry composition for a ceramic green sheet becomes highly viscous and the coatability to the support is lowered.

The present disclosure has been made in view of the above circumstances, and the main purpose thereof is to obtain a ceramic green sheet having high strength and excellent thermal decomposability while keeping the viscosity of the slurry composition low. It is to provide a binder for manufacturing.

The present disclosures have completed the present disclosure by using a specific block copolymer as a result of diligent studies to solve the above problems. According to the present disclosure, the following means are provided.

[1] A binder for producing a ceramic green sheet containing a block copolymer, wherein the block copolymer is mainly composed of a structural unit derived from a vinyl monomer and has substantially no polyvinyl acetal structure. A binder for producing a ceramic green sheet, which also has a hydrogen-bonding functional group.
[2] The block copolymer is a binder for producing a ceramic green sheet according to [1], which has 70% by mass or more of structural units derived from (meth) acrylic monomers with respect to all structural units.
[3] The block copolymer has a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an imide group-containing vinyl monomer, and is the ceramic green sheet of [1] or [2]. Binder for manufacturing.
[4] The ceramic green according to any one of [1] to [3], wherein the block copolymer has 5% by mass or more and 70% by mass or less of structural units derived from a methacrylic acid ester compound with respect to all structural units. Binder for sheet production.
[5] The block copolymer has any one of [1] to [4], which comprises a polymer block having a glass transition temperature of 30 ° C. or higher and a polymer block having a glass transition temperature of less than 30 ° C. Binder for manufacturing ceramic green sheets.

[6] The block copolymer has 5% by mass or more and 25% by mass or less of structural units derived from a vinyl monomer having a hydrogen-bonding functional group with respect to all structural units [1] to [5]. ] Any of the ceramic green sheet manufacturing binders.
[7] The block copolymer has a molecular weight distribution (Mw / Mn) represented by a ratio of a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 3.0 or less, [1] to [ 6] A binder for producing a ceramic green sheet.
[8] A slurry composition containing the binder for producing a ceramic green sheet according to any one of the above [1] to [7] and a ceramic powder.
[9] A ceramic green sheet formed by using the slurry composition of the above [8].
[10] A method for manufacturing a multilayer ceramic capacitor using the ceramic green sheet of the above [9].

According to the binder for producing a ceramic green sheet of the present disclosure, it is possible to obtain a ceramic green sheet having high strength and excellent thermal decomposability while keeping the viscosity of the slurry composition low.

Hereinafter, the present disclosure will be described in detail. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacrylic, and "(meth) acrylate" means acrylate and / or methacrylate.

<< Binder for manufacturing ceramic green sheets >>
The binder for producing a ceramic green sheet of the present disclosure is used for forming a ceramic powder to produce a laminated ceramic green sheet. The binder for producing a ceramic green sheet of the present disclosure is a block copolymer mainly composed of a structural unit derived from a vinyl monomer, has substantially no polyvinyl acetal structure, and has a hydrogen-binding functional group (hereinafter, "" Also referred to as "block copolymer (P)").

(Vinyl monomer)
The block copolymer (P) has a structural unit derived from a vinyl monomer. Examples of the vinyl monomer include (meth) acrylic monomers, aromatic vinyl monomers, and imide group-containing vinyl monomers.

In addition, in this specification, "mainly a structural unit derived from a vinyl monomer" means that the content ratio of the structural unit derived from a vinyl monomer in the block copolymer (P) is the same as that of the block. It is 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 99% by mass or more, based on the total structural unit of the polymer (P).

Examples of the (meth) acrylic monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester compound, (meth) acrylic acid aliphatic cyclic ester compound, and (meth) acrylic acid aromatic ester compound. (Meta) acrylic acid alkoxyalkyl compound, (meth) acrylic acid hydroxyalkyl compound, (di) alkylaminoalkyl (meth) acrylate compound, epoxy group-containing (meth) acrylic acid ester compound, polyoxyalkylene (meth) acrylate compound, etc. Can be mentioned.

Specific examples of these include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, and (meth) as the (meth) acrylic acid alkyl ester compound. N-butyl acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, amyl (meth) acrylate, n-hexyl (meth) acrylate, (meth) N-octyl acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, etc.;
As an aliphatic cyclic ester compound of (meth) acrylic acid, cyclohexyl (meth) acrylic acid, methylcyclohexyl (meth) acrylic acid, tert-butylcyclohexyl (meth) acrylic acid, cyclododecyl (meth) acrylic acid, (meth). Isobornyl acrylate, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc.;
As aromatic ester compounds of (meth) acrylic acid, phenyl (meth) acrylic acid, benzyl (meth) acrylic acid, phenoxymethyl (meth) acrylic acid, 2-phenoxyethyl (meth) acrylic acid and 3 (meth) acrylic acid -Phenoxypropyl, etc.;
As the (meth) acrylic acid alkoxyalkyl compound, (meth) acrylate methoxymethyl, (meth) acrylate ethoxymethyl, (meth) acrylate methoxyethyl, (meth) acrylate ethoxyethyl, (meth) acrylate n-propoxy Ethyl, n-butoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxypropyl (meth) acrylate, etc.;
As the (meth) hydroxyalkyl acrylate compound, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like are used;
As (di) alkylaminoalkyl (meth) acrylate compounds, N- [2- (methylamino) ethyl] (meth) acrylate, N- [2- (dimethylamino) ethyl] (meth) acrylate, N- [2- [2- (Ethylamino) ethyl] (meth) acrylate and N- [2- (diethylamino) ethyl] (meth) acrylate and the like;
As the epoxy group-containing (meth) acrylic acid ester compound, glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate and the like;
Examples of the polyoxyalkylene (meth) acrylate compound include polyoxyethylene (meth) acrylate and polyoxypropylene (meth) acrylate, respectively. As the (meth) acrylic monomer, one of these can be used alone or in combination of two or more.

When the (meth) acrylic monomer used for producing the block copolymer (P) is used as a binder for producing a ceramic green sheet, it has high pyrolysis during firing and can reduce the residue of the binder. Among the above, the compound represented by the following formula (1) is preferable.
CH ₂ = CR ¹ -C (= O) -O- (R ² O) n-R ³ ... (1)
(In the formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is a linear or branched alkylene group having 2 to 6 carbon atoms, and R ³ is a hydrogen atom or a carbon number. It is an alkyl group having 1 to 20, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. N is an integer of 0 to 50. In the case of two or more, the plurality of R ^2s in the equation may be the same or different from each other.)

The (meth) acrylic monomer used for producing the block copolymer (P) preferably contains a (meth) acrylic acid alkyl ester compound in that the dispersion stability of the ceramic powder can be further enhanced. .. Among these, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate. , (Meth) tert-butyl acrylate, and 2-ethylhexyl (meth) acrylate, preferably at least one selected from the group.

The block copolymer (P) is preferably a polymer mainly composed of a structural unit derived from a (meth) acrylic monomer (hereinafter, also referred to as “(meth) acrylic unit”). The content ratio of the (meth) acrylic unit in the block copolymer (P) is preferably 70% by mass or more with respect to the total structural units of the block copolymer (P). When the block copolymer (P) has 70% by mass or more of (meth) acrylic units, it is preferable in that it can be a binder resin having excellent thermal decomposability at the time of firing. From this point of view, the content ratio of the (meth) acrylic unit is more preferably 80% by mass or more, further preferably 85% by mass or more, and 87% by mass or more with respect to the total structural unit of the block copolymer (P). Especially preferable.

The block copolymer (P) preferably has a structural unit derived from a methacrylic acid ester compound (hereinafter, also referred to as “methacrylic acid ester unit”). Since the block copolymer (P) has a methacrylic acid ester unit, it is preferable in that the thermal decomposability of the binder can be further enhanced. The methacrylic acid ester unit is preferably a structural unit derived from the compound represented by the following formula (2).
CH ₂ = C (CH ₃ ) -C (= O) -O- (R ⁴ O) _m -R ⁵ ... (2)
In the formula (2), R ⁴ is a linear or branched alkylene group having 2 to 6 carbon atoms, and R ⁵ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and 3 to 20 carbon atoms. Cycloalkyl group, aryl group having 6 to 20 carbon atoms, or aralkyl group having 7 to 20 carbon atoms. M is an integer of 0 to 50. When m is 2 or more, a plurality of ^R4s in the formula. May be the same or different from each other.)

Specific examples of the compound represented by the above formula (2) include a methacrylic acid alkyl ester compound exemplified as a vinyl monomer constituting the block copolymer (P), an aliphatic cyclic ester compound of methacrylic acid, and methacrylic acid. Examples thereof include an aromatic ester compound of an acid, an alkoxyalkyl methacrylate compound, a hydroxyalkyl methacrylate compound, and a polyoxyalkylene methacrylate compound.

The methacrylic acid ester unit contained in the block copolymer (P) is selected from the group consisting of an alkyl methacrylate ester compound, an alkoxyalkyl methacrylate compound, a hydroxyalkyl methacrylate compound, and a polyoxyalkylene methacrylate compound. A structural unit derived from at least one of the above is preferable, and a structural unit derived from at least one selected from the group consisting of an alkyl methacrylate ester compound, an alkoxyalkyl methacrylate compound, and a hydroxyalkyl methacrylate compound is more preferable. Among these, it is particularly preferable that the block copolymer (P) has a structural unit derived from at least one selected from the group consisting of an alkyl methacrylate ester compound and an alkoxyalkyl methacrylate compound.

The content ratio of the methacrylic acid ester unit in the block copolymer (P) is preferably 3% by mass or more, more preferably 5% by mass or more, and 10% by mass with respect to the total structural units of the block copolymer (P). % Or more is more preferable. The upper limit of the content ratio of the methacrylic acid ester unit is preferably 70% by mass or less with respect to the total structural unit of the block copolymer (P) in that the decrease in strength and flexibility of the ceramic green sheet can be suppressed. , 65% by mass or less is more preferable, and 60% by mass or less is further preferable. As the methacrylic acid ester compound, one kind or a combination of two or more kinds can be used.

The block copolymer (P) has a structural unit derived from an aromatic vinyl monomer (hereinafter, also referred to as “aromatic vinyl unit”) and a structural unit derived from an imide group-containing vinyl monomer (hereinafter, “imide group”). When it has a "containing vinyl unit"), it is preferable in that the strength of the ceramic green sheet produced by using the block copolymer (P) can be further increased.

The aromatic vinyl monomer is a monomer having a structure in which a polymerizable carbon-carbon double bond is bonded to an aromatic ring. Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, and m-ethyl. Styrene, p-ethylstyrene, pn-butylstyrene, p-isobutylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-chlorostyrene, m-chlorostyrene , P-chlorostyrene, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol, o-vinyl benzoic acid, m-vinyl benzoic acid , P-vinyl benzoic acid, styrene-based monomers such as divinylbenzene, vinyl naphthalene and the like. As the aromatic vinyl monomer, a styrene-based monomer can be preferably used. As the aromatic vinyl monomer, one or more of these can be used.

Examples of the imide group-containing vinyl monomer include maleimide compounds such as maleimide and N-substituted maleimide compounds; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-2-ethylhexylitaconimide, and N-. Itaconimide compounds such as cyclohexylitaconimide; citraconimide compounds such as N-methylcitraconimide, N-ethylcitraconimide, N-butylcitraconimide, N-2-ethylhexylcitraconimide, N-cyclohexylcitraconimide; N- (2- (2- (Meta) acryloyloxyethyl) Imide succinate, N- (2- (meth) acryloyloxyethyl) maleimide, N- (2- (meth) acryloyloxyethyl) phthalate imide, N- (4- (meth) acryloyl) Examples thereof include (meth) acrylicimide compounds such as oxybutyl) phthalate imide. Of these, maleimide compounds are preferable because they exhibit high copolymerizability with styrene-based monomers.

As the maleimide compound, a maleimide and an N-substituted maleimide compound can be preferably used. Examples of the N-substituted maleimide compound include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, and N. -N-alkyl substituted maleimide compounds such as pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide; N-cyclopentylmaleimide, N-cyclohexylmaleimide and the like. Cycloalkyl-substituted maleimide compounds; N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide; N-phenylmaleimide, N- (4-hydroxyphenyl) maleimide, N- (4-acetylphenyl) maleimide, N- (4-methoxy) Examples thereof include N-aryl substituted maleimide compounds such as phenyl) maleimide, N- (4-ethoxyphenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromophenyl) maleimide. As the imide group-containing vinyl monomer, one or more of these can be used.

（式（３）中、Ｒ^６は、水素原子、炭素数１～３のアルキル基、シクロヘキシル基、フェニル基、又は、フェニル基の任意の位置にヒドロキシ基、炭素数１～２のアルコキシ基、アセチル基若しくはハロゲン原子が結合した置換フェニル基を表す。） Among the above, the compound represented by the following formula (3) is preferable as the imide group-containing vinyl monomer used for producing the block copolymer (P).

(In the formula (3), R ⁶ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group, or an alkoxy group having 1 to 2 carbon atoms at an arbitrary position of the phenyl group. Represents a substituted phenyl group to which an acetyl group or a halogen atom is bonded.)

When the block copolymer (P) has an aromatic vinyl unit, the content ratio of the aromatic vinyl unit is preferably 0.5% by mass or more with respect to the total structural units of the block copolymer (P). It is more preferably mass% or more, and even more preferably 2% by mass or more. The upper limit of the aromatic vinyl unit is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, based on the total structural units of the block copolymer (P).

When the block copolymer (P) has an imide group-containing vinyl unit, the content ratio of the imide group-containing vinyl unit is preferably 0.5% by mass or more with respect to the total structural units of the block copolymer (P). 1% by mass or more is more preferable, and 2% by mass or more is further preferable. The upper limit of the imide group-containing vinyl unit is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, based on the total structural units of the block copolymer (P). Further, when the aromatic vinyl monomer and the imide group-containing vinyl monomer are used in combination in the production of the block copolymer (P), the aromatic vinyl monomer is compared with 1 mol of the imide group-containing vinyl monomer. The usage ratio of the above is preferably 0.01 to 20 mol, more preferably 0.1 to 10 mol, and further preferably 0.2 to 5 mol.

The block copolymer (P) is a vinyl monomer other than the (meth) acrylic monomer, the aromatic vinyl monomer and the imide group-containing vinyl monomer, as long as the effects exhibited by the present disclosure are not impaired. It may have a structural unit derived from (hereinafter, also referred to as “other vinyl monomer”). Examples of other vinyl monomers include (meth) acrylamide compounds such as (meth) acrylamide, tert-butyl (meth) acrylamide, and N-methylolacrylamide; vinyl acetate, vinyl benzoate, and the like. The content ratio of the structural units derived from other vinyl monomers in the block copolymer (P) is preferably 5% by mass or less, more preferably 5% by mass or less, based on the total structural units of the block copolymer (P). It is 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less.

(Hydrogen-bonding functional group)
The block copolymer (P) has a hydrogen-bonding functional group. Examples of the hydrogen-binding functional group of the block copolymer (P) include a hydroxyl group, an amino group (including a primary amino group, a secondary amino group and a tertiary amino group), a carboxy group, an amide group and a thiol group. , A sulfonyl group and the like. Of these, a hydroxyl group, an amino group and a carboxy group are preferable, and a hydroxyl group is particularly preferable, in that the adsorptivity to the ceramic powder is high and the dispersion stability of the ceramic powder can be improved.

The block copolymer (P) is hydrogen-bonded because it is easy to adjust the amount of hydrogen-bonding functional groups of the block copolymer (P) and it is easy to produce a block copolymer having hydrogen-bonding functional groups. It is preferably produced using a vinyl monomer having a sex functional group (hereinafter, also referred to as “hydrogen bond-containing group-containing vinyl monomer”). The hydrogen-binding group-containing vinyl monomer preferably has a hydroxyl group, and specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and (meth) acrylate 3. -Hydroxyalkyl compounds (meth) acrylates such as hydroxypropyl, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; polyalkylene glycol (polyethylene glycol). , Polypropylene glycol, etc.) mono (meth) acrylic acid ester compounds; hydroxy such as p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol and o-isopropenylphenol. Styrene compounds; hydroxy-substituted maleimide compounds such as N- (4-hydroxyphenyl) maleimide and the like can be mentioned. Among the above, it is particularly preferable to use the hydroxyalkyl (meth) acrylate compound as the hydrogen-bonding group-containing vinyl monomer.

In the block copolymer (P), the content ratio of the structural unit derived from the hydrogen-binding group-containing vinyl monomer is the same as that of the block copolymer (P) from the viewpoint of sufficiently increasing the dispersion stability of the inorganic particles. It is preferably 5% by mass or more, more preferably 7% by mass or more, and further preferably 8% by mass or more with respect to all structural units. The upper limit of the content ratio of the structural unit derived from the hydrogen-bonding group-containing vinyl monomer is set to the total structural unit of the block copolymer (P) from the viewpoint of ensuring the solubility of the slurry composition in the solvent component. On the other hand, it is preferably 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less. As the hydrogen-bonding group-containing vinyl monomer, only one type may be used, or two or more types may be used in combination.

The block copolymer (P) is a polymer mainly composed of (meth) acrylic units and has substantially no polyvinyl acetal structure. Here, in the present specification, "substantially having no polyvinyl acetal structure" means that the block copolymer (P) does not exhibit the characteristics derived from the polyvinyl acetal structure. However, it is permissible for the block copolymer (P) to have a trace amount of polyvinyl acetal structure that does not interfere with the effects of the present disclosure. Specifically, the proportion of the polyvinyl acetal structure in the block copolymer (P) is typically 2% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass or less, and further. It is preferably 0.1% by mass or less and does not have a polyvinyl acetal structure.

(Structure of block copolymer (P))
As long as the block copolymer (P) has two or more polymer blocks, the number of polymer blocks in one molecule, the arrangement order, and the like are not particularly limited. Specific examples of the block copolymer (P) include a (AB) diblock composed of a polymer block (A) and a polymer block (B), and a polymer block (A) / polymer block (B). ) / (ABA) triblock composed of the polymer block (A), (ABC) triblock composed of the polymer block (A), the polymer block (B) and the polymer block (C), and the like. .. Further, the block copolymer (P) may be a polyblock copolymer having four or more polymer blocks. Of these, the number of polymer blocks per block copolymer (P) molecule is 2 in that a slurry composition having high dispersion stability of ceramic powder and sufficiently low viscosity can be efficiently produced. More than 7 pieces are preferable, 2 pieces or more and 5 pieces or less are more preferable, and 2 or 3 pieces are further preferable.

In the at least two polymer blocks of the block copolymer (P), all the blocks may have hydrogen-bonding functional groups, or only a part of the two or more polymer blocks. May have hydrogen-bonding functional groups. From the viewpoint of sufficiently increasing the dispersion stability of the ceramic powder, it is preferable that at least two polymer blocks of the block copolymer (P) satisfy the following [i] or [ii].
[I] Of the two or more polymer blocks, some blocks have hydrogen-bonding functional groups and the remaining blocks do not have hydrogen-bonding functional groups.
[Ii] Two or more polymer blocks have hydrogen-bonding functional groups, and the content ratio of structural units derived from the hydrogen-bonding group-containing vinyl monomer differs between the polymer blocks.

Each polymer block of the block copolymer (P) is mainly composed of a structural unit derived from a vinyl monomer. In one preferred embodiment, the block copolymer (P) is a polymer block having a glass transition temperature (Tg) of 30 ° C. or higher (hereinafter, also referred to as “hard segment”) and a polymer having a Tg of less than 30 ° C. It has a block (hereinafter also referred to as "soft segment"). According to this aspect, as the block copolymer (P), it is possible to obtain a polymer capable of forming a pseudo-crosslinked structure by forming a microphase-separated structure or the like. Further, the ceramic green sheet produced by using such a block copolymer (P) is suitable in that the breaking energy can be increased while the slurry viscosity is low and the mechanical properties can be improved. ..

The Tg of the hard segment is preferably 50 ° C. or higher, more preferably 75 ° C. or higher, and even more preferably 100 ° C. or higher. Further, the Tg of the hard segment is generally 250 ° C. or lower due to restrictions on the monomer used as a raw material. The range of Tg of the hard segment is preferably 50 ° C. or higher and 250 ° C. or lower, more preferably 75 ° C. or higher and 250 ° C. or lower, and further preferably 100 ° C. or higher and 250 ° C. or lower. In the present specification, the glass transition temperature (Tg) of the polymer block is a value calculated by the formula of Fоx as described in Examples described later.

The Tg of the soft segment is preferably 25 ° C. or lower, more preferably 20 ° C. or lower, and even more preferably 10 ° C. or lower. The Tg of the soft segment is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and even more preferably −20 ° C. or higher. The range of Tg of the soft segment is preferably −50 ° C. or higher and lower than 30 ° C., more preferably −30 ° C. or higher and lower than 30 ° C., and further preferably −20 ° C. or higher and lower than 30 ° C.

The mass ratio of the hard segment in the block copolymer (P) is preferably 3% by mass or more, more preferably 5% by mass or more, from the viewpoint that a pseudo-crosslinked structure can be formed by forming a microphase-separated structure or the like. It is more preferably 10% by mass or more. The upper limit of the mass ratio is preferably 50% by mass or less, more preferably 35, in order to suppress an increase in the viscosity of the slurry composition and to suppress a decrease in the flexibility of the ceramic green sheet. It is mass% or less, more preferably 20% or less. The mass ratio of the hard segments in the block copolymer (P) is the charging ratio of each block when the block copolymer (P) is produced (hereinafter, also referred to as “charged block ratio”, unit: mass ratio). And the value calculated from the polymerization rate (%) of each monomer.

When the block copolymer (P) has a hard segment and a soft segment, it is preferable that the hard segment contains a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit. According to the polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit, a polymer capable of forming a segment having a sufficiently high glass transition temperature and forming a pseudo-crosslinked structure by forming a microphase-separated structure or the like can be easily used. It is preferable in that it can be manufactured. This polymer block is preferably a polymer block having an aromatic vinyl unit and a structural unit derived from a maleimide compound, and more preferably a structural unit derived from a styrene-based monomer and a maleimide compound. It is a polymer block having a structural unit from which it is derived. In the polymer block, the total content ratio of the aromatic vinyl unit and the imide group-containing vinyl unit is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 55% by mass or more.

Preferred embodiments of the block structure of the block copolymer (P) include the following embodiments [1] and [2].
[1] A block copolymer containing a first block mainly composed of a (meth) acrylic unit and a second block mainly composed of a (meth) acrylic unit and having a different monomer composition from the first block.
[2] A block copolymer containing a polymer block mainly composed of a (meth) acrylic unit and a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit.

In the case of the above [1], more specifically, the following aspects [1-1] and [1-2] can be mentioned.
[1-1] A first block mainly composed of (meth) acrylic units and a second block mainly composed of (meth) acrylic units are included, and one of the first block and the second block is a hydrogen-bonding functional group. A block copolymer having a group and the other having no hydrogen-bonding functional group.
[1-2] A first block mainly composed of (meth) acrylic units and a second block mainly composed of (meth) acrylic units are included, and both the first block and the second block have hydrogen-bonding functional groups. A block copolymer that has and has a different content ratio of structural units derived from a hydrogen-bonding group-containing vinyl monomer among the polymer blocks.

In the case of the above [2], more specifically, the following aspects [2-1] and [2-2] can be mentioned.
[2-1] A polymer block mainly composed of a (meth) acrylic unit and a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit are included, and one of these polymer blocks is hydrogen-bondable. A block copolymer having a functional group and the other having no hydrogen-binding functional group.
[2-2] A polymer block mainly composed of a (meth) acrylic unit and a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit are included, and both of these polymer blocks are hydrogen-bonding functional groups. A block copolymer having a polymer block having a different content ratio of structural units derived from a hydrogen-binding group-containing vinyl monomer.

For the block copolymer (P), the polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is preferably in the range of 10,000 to 500,000. When Mn is 10,000 or more, the strength of the ceramic green sheet produced by using the block copolymer (P) can be sufficiently increased, which is preferable. Further, when Mn is 500,000 or less, it is preferable that the viscosity of the slurry composition becomes too high, and the coatability and handleability can be sufficiently ensured. The Mn of the block copolymer (P) is more preferably 20,000 or more, still more preferably 30,000 or more, and particularly preferably 50,000 or more. The Mn of the block copolymer (P) is more preferably 300,000 or less, further preferably 250,000 or less, and particularly preferably 150,000 or less.

For the block copolymer (P), the polystyrene-equivalent weight average molecular weight (Mw) measured by GPC is preferably in the range of 30,000 to 700,000. The Mw of the block copolymer (P) is more preferably 40,000 or more, further preferably 50,000 or more, and particularly preferably 70,000 or more. The Mw of the block copolymer (P) is more preferably 500,000 or less, further preferably 300,000 or less, and particularly preferably 250,000 or less.

The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in the block copolymer (P) is a slurry composition containing the block copolymer (P). It is preferably 3.0 or less in that it can prevent the viscosity of the sample from becoming too high. Further, when Mw / Mn is 3.0 or less, there are few high molecular weight components that greatly increase the viscosity of the slurry composition, and the viscosity of the slurry composition can be sufficiently lowered, so that the block copolymer (P) is high. It is possible to increase the molecular weight. Therefore, the strength of the ceramic green sheet obtained by using the slurry composition can be increased. Mw / Mn is more preferably 2.8 or less, still more preferably 2.5 or less, and particularly preferably 2.2 or less. The lower limit of Mw / Mn is preferably 1.1 or more from the viewpoint of ease of manufacture.

<Manufacturing of block copolymer (P)>
The block copolymer (P) is preferably produced by polymerizing the above-mentioned monomer by a living radical polymerization method in that a block copolymer (P) having a sufficiently small molecular weight distribution can be obtained. For example, in the case of the solution polymerization method, the target block copolymer is obtained by charging an organic solvent and a monomer into a reactor, adding a polymerization control agent and a radical polymerization initiator, and preferably heating and copolymerizing. (P) can be obtained. The method of charging each raw material may be a batch-type initial batch charging in which all the raw materials are collectively charged, or a semi-continuous charging in which at least a part of the raw materials is continuously supplied into the reactor, and all the raw materials are continuously supplied. At the same time, a continuous polymerization method may be used in which the product is continuously extracted from the reactor.

In the production of the block copolymer (P), a known polymerization method can be adopted as the living radical polymerization method. Specific examples of the living radical polymerization method to be used include a living radical polymerization method having an exchange chain transfer mechanism, a living radical polymerization method having a bond-dissociation mechanism, and a living radical polymerization method having an atomic transfer mechanism. Specific examples of these include reversible addition-cleaving chain transfer polymerization method (RAFT method), iodine transfer polymerization method, polymerization method using organic tellurium compound (TERP method), and organic antimony as living radical polymerization of exchange chain transfer mechanism. Polymerization method using compounds (SBRP method), polymerization method using organic bismuth compound (BIRP method), etc .; as living radical polymerization of bond-dissociation mechanism, nitroxy radical method (NMP method), etc .; as atom transfer mechanism. Atom transfer radical polymerization method (ATRP method) and the like can be mentioned respectively. Among these, the living radical polymerization method having an exchange chain transfer mechanism is preferable because it can be applied to the widest range of vinyl monomers and has excellent polymerization controllability, and the RAFT method is used from the viewpoint of ease of implementation. Is particularly preferred.

In the RAFT method, polymerization proceeds via a reversible chain transfer reaction in the presence of a polymerization control agent (RAFT agent) and a free radical polymerization initiator. As the RAFT agent, various known RAFT agents such as a dithioester compound, a zantate compound, a trithiocarbonate compound and a dithiocarbamate compound can be used. As the RAFT agent, a monofunctional compound having only one active site may be used, or a polyfunctional compound having two or more active sites may be used. Block copolymers of A- (BA) n-type structure, B- (AB) n-type structure, or (AB) m-C- (BA) n-type structure (where n and m are integers of 1 or more). In the case of production, it is preferable to use a bifunctional RAFT agent because it is easy to efficiently obtain the block copolymer. The amount of the RAFT agent used is appropriately adjusted according to the number average molecular weight (Mn) of the target block copolymer.

As the polymerization initiator used in the polymerization by the RAFT method, known radical polymerization initiators such as azo compounds, organic peroxides and persulfates can be used. Among these, azo compounds are preferable because they are easy to handle for safety and side reactions during radical polymerization are unlikely to occur. Specific examples of the azo compound include 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2, 4-Dimethylvaleronitrile), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1- Carbonitrile), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide) and the like. As the radical polymerization initiator, only one type may be used, or two or more types may be used in combination.

The amount of the radical polymerization initiator used is not particularly limited, but is preferably 1 part by mass or less, and 0.8 parts by mass with respect to 1 part by mass of the RAFT agent, from the viewpoint of obtaining a polymer having a smaller molecular weight distribution. The following is more preferable. From the viewpoint of stabilizing the polymerization reaction, the lower limit of the amount of the radical polymerization initiator used is preferably 0.01 part by mass or more, and 0.05 part by mass or more with respect to 1 part by mass of the RAFT agent. It is more preferable to do so. The amount of the radical polymerization initiator used with respect to 1 part by mass of the RAFT agent is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.8 part by mass.

In the polymerization reaction by the RAFT method, the reaction temperature is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 45 ° C. or higher and 90 ° C. or lower, and further preferably 50 ° C. or higher and 80 ° C. or lower. When the reaction temperature is 40 ° C. or higher, it is preferable that the polymerization reaction can proceed smoothly, and when the reaction temperature is 100 ° C. or lower, side reactions can be suppressed and restrictions on the initiators and solvents that can be used are relaxed. It is preferable in that it is done. The reaction time can be appropriately set depending on the monomer to be used and the like, but is preferably 1 hour or more and 48 hours or less, and more preferably 3 hours or more and 24 hours or less. The polymerization reaction may be carried out in the presence of a chain transfer agent (for example, an alkylthiol compound having 2 to 20 carbon atoms), if necessary.

For example, when a diblock copolymer composed of a polymer block (A) and a polymer block (B) is obtained by RAFT polymerization, as a specific polymerization method, each block is sequentially subjected to a monofunctional RAFT agent. Examples thereof include a method of producing a target diblock copolymer by polymerization. In this method, first, as a first polymerization step, a monomer is polymerized in the presence of a monofunctional RAFT agent and a radical polymerization initiator to obtain a polymer block (A). Next, as a second polymerization step, the monomer is polymerized in the presence of the polymer block (A) to obtain a polymer block (A) -polymer block (B). In this way, a block copolymer (P) having two blocks can be obtained. Further, by repeating the above polymerization step, a block copolymer (P) having 3 or more blocks can be produced. For example, after obtaining the polymer block (A) -polymer block (B) by the first polymerization step and the second production step, the monomer is in the presence of the polymer block (A) -polymer block (B). By polymerizing, a triblock copolymer composed of a polymer block (A) -polymer block (B) -polymer block (C), or a polymer block (A) -polymer block (B) -heavy A triblock copolymer composed of the coalesced block (A) can be obtained.

Further, as a block copolymer having 5 blocks, the polymer block (A) -polymer block (B) -polymer block (C) -polymer block (B) -polymer block (A) is subjected to RAFT polymerization. ), As a method for producing the pentablock copolymer, in addition to the method of sequentially polymerizing each block using a monofunctional RAFT agent as described above, a bifunctional RAFT agent is used. Examples thereof include a method of producing a desired pentablock copolymer by performing three-step polymerization. In this method, first, as the first polymerization step, a bifunctional RAFT agent (for example, 1,4? Bis (n? Dodecylsulfanylthiocarbonylsulfanylmethyl) benzene, S, S-dibenzyltrithiocarbonate, etc.) and In the presence of a radical polymerization initiator, the monomer is polymerized to obtain a polymer block (A). Next, as a second polymerization step, the polymer block (A) -polymer block (B) -polymer block (A) is obtained by polymerizing the monomer in the presence of the polymer block (A). Further, as a third polymerization step, the polymer block (A) -polymer is formed by polymerizing the monomer in the presence of the polymer block (A) -polymer block (B) -polymer block (A). A pentablock copolymer composed of block (B) -polymer block (C) -polymer block (B) -polymer block (A) can be obtained. The method using a bifunctional RAFT agent is suitable in that the manufacturing process can be simplified and the production efficiency can be improved.

In the production of the block copolymer (P), a known polymerization solvent can be used in living radical polymerization. Specifically, aromatic compounds such as benzene, toluene, xylene and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, dimethylsulfoxide, Examples include alcohol and water. When the block copolymer (P) is produced by a solution polymerization method, the block copolymer (P) dissolved in the polymerization solvent is subjected to a known desolvation method such as a reprecipitation method and a drying method such as heat treatment. Can be isolated. Further, it may be carried out in the form of bulk polymerization or the like without using a polymerization solvent.

<< Slurry composition >>
The slurry composition of the present disclosure is a polymer composition used for producing a ceramic green sheet, and contains a block copolymer (P) and a ceramic powder. As the ceramic powder, a material known as a material constituting the dielectric layer of a ceramic capacitor can be used, and for example, a dielectric such as barium titanate, titanium oxide, alumina, zirconia, zinc oxide, aluminum silicate, and silicon nitride. Examples include powder. The content of the block copolymer (P) in the slurry composition is preferably 1 to 70 parts by mass, and more preferably 3 to 50 parts by mass with respect to 100 parts by mass of the ceramic powder.

A solvent is added to the slurry composition, if necessary. As the solvent, an organic solvent can be preferably used, for example, hydrocarbons such as toluene, xylene, methylcyclohexane and tarpineol; alcohols such as ethanol, n-propanol, isopropanol and n-butanol; acetone, methyl ethyl ketone and methyl isobutyl ketone. Ketones such as; ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, isobutyl acetate, propylene glycol monomethyl ether acetate, and the like. As the solvent, one type can be used alone or two or more types can be used in combination. The content of the solvent in the slurry composition is preferably 10 to 500 parts by mass, and more preferably 30 to 200 parts by mass with respect to 100 parts by mass of the ceramic powder.

In addition to the block copolymer (P), ceramic powder and solvent, the slurry composition may contain known additives such as a plasticizer, a dispersant, a leveling agent and an antifoaming agent. These blending ratios can be appropriately set according to each additive as long as the effects of the present disclosure are not impaired. The slurry composition can be prepared, for example, by mixing the ceramic powder with a binder and, if necessary, a solvent or the like by a bead mill or the like.

The viscosity of the slurry composition is preferably 80 mPa · s or more, and more preferably 100 mPa · s or more. By setting the slurry viscosity to 80 mPa · s or more, the thin film shape can be secured when the slurry composition is applied onto the support. The upper limit of the slurry viscosity is preferably 3000 mPa · s or less, and more preferably 2000 mPa · s or less, from the viewpoint of ensuring coatability. The viscosity of the slurry composition is a value measured at 25 ° C. using a B-type viscometer with the rotor rotation speed set to 6 rpm.

<< Ceramic Green Sheet and Multilayer Ceramic Capacitor >>
The ceramic green sheet of the present disclosure is produced by using a slurry composition containing a block copolymer (P) and a ceramic powder. Further, by laminating the obtained ceramic green sheets, a laminated ceramic capacitor having a dielectric layer formed by the above slurry composition can be manufactured. The method for manufacturing the ceramic green sheet and the monolithic ceramic capacitor is not particularly limited, and a known method can be used.

Specifically, first, a slurry composition containing a block copolymer (P) and a ceramic powder is applied onto a support such as PET that has been mold-released. Subsequently, a volatile component is removed from the slurry composition on the support by a drying treatment to form a film, and a ceramic green sheet is obtained. A metal paste to be an internal electrode is printed on the ceramic green sheet, dried, and the ceramic green sheet with electrodes is peeled off from the support. A plurality of these are laminated and heat-bonded to produce a laminated body, and the laminated body is cut into a predetermined shape to obtain a ceramic green chip. After degreasing (thermal decomposition of the binder) by heat-treating the obtained ceramic green chips, the ceramic is sintered at a high temperature. In this way, a monolithic ceramic capacitor is obtained.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified. The analysis method of the polymer obtained in the production example and the comparative production example is as follows.

<Molecular weight measurement>
The obtained polymer was subjected to gel permeation chromatography (GPC) measurement under the following conditions to obtain a number average molecular weight (Mn) and a weight average molecular weight (Mw) in terms of polystyrene. Further, the molecular weight distribution (Mw / Mn) was calculated from the obtained Mn and Mw values.
○ Measurement conditions Column: TSKgel SuperMultipore HZ-M x 4 manufactured by Tosoh Corporation Solvent: Tetrahydrofuran Temperature: 40 ° C.
Detector: RI
Flow velocity: 600 μL / min

<Glass transition temperature (Tg)>
The glass transition temperature (Tg) of the polymer block was calculated by the Fox formula represented by the following formula (4) based on the glass transition temperature of the homopolymer of each monomer constituting the polymer block.
1 / Tg = (W ₁ / Tg ₁ ) + (W ₂ / Tg ₂ ) + ... + (W _n / Tg _n )
… (4)
The formula (4) is a calculation formula when the polymer for which Tg is calculated is a copolymer composed of monomer 1, monomer 2, ..., And monomer n (n is an integer). In formula (4), W ₁ , W ₂ , ... And W _n indicate the mass fraction of each monomer in the polymer block, and Tg ₁ , Tg ₂ , ... And Tg _n are homopolymers of each monomer. The glass transition temperature (unit: K) is shown.

1. 1. Production of Block Copolymer <Production Example 1> Production of Polymer A / First Polymerization Step (Production of Polymer Block (A))
In a flask equipped with a stirrer, a thermometer, a reflux cooler and a nitrogen introduction tube, 19.5 parts of methyl acrylate (hereinafter also referred to as “MA”) and n-butyl acrylate (hereinafter also referred to as “BA”) 10. 5 parts, 2-hydroxyethyl acrylate (hereinafter also referred to as "HEA") 70 parts, 2-{[(2-carboxyethyl) sulfanylthiocarbonyl] sulfanyl} propanoic acid (hereinafter also referred to as "CBSTSP") 1.60 parts Add 0.14 parts of 2,2'-azobis (2-methylbutyronitrile) (hereinafter also referred to as "ABN-E") and 184 parts of acetonitrile, degas sufficiently with nitrogen bubbling, and in a constant temperature bath at 70 ° C. Polymerization was started at. After 5 hours, the mixture was cooled to room temperature to terminate the polymerization. The amount of residual monomer was measured by gas chromatography (GC) measurement, and the monomer polymerization rate and block composition were calculated. The monomer polymerization rates were MA38%, BA33%, and HEA42%, and the block composition is shown in Table 2. It was a street. The block composition was calculated from the monomer polymerization rate (the same applies hereinafter). When the molecular weight of the polymer was measured by GPC measurement (in terms of polystyrene), it was Mn5,600, Mw6,100, and Mw / Mn1.08.

-Second polymerization step (manufacturing of polymer block (B))
Next, 90 parts of MA, 210 parts of BA, 300 parts of methyl methacrylate (hereinafter also referred to as "MMA"), ABN-E1.20 parts, and 280 parts of acetonitrile were charged, sufficiently degassed by nitrogen bubbling, and placed in a constant temperature bath at 80 ° C. Polymerization was restarted. After 5 hours, the mixture was cooled to room temperature to terminate the polymerization, and a solution containing a block copolymer (referred to as "polymer A") was obtained. When the amount of residual monomer was measured by gas chromatography (GC) measurement and the monomer polymerization rate and block composition were calculated, each monomer polymerization rate was 88% of MA (residual part of the first polymerization step and additional part of the second polymerization step). , BA (residual part of the first polymerization step and additional part of the second polymerization step) 87%, MMA> 99%, HEA (residual part of the first polymerization step) 90%, and the block composition was as shown in Table 2. .. When the molecular weight of the block copolymer was measured by GPC measurement (in terms of polystyrene), it was Mn60,000, Mw114,800, and Mw / Mn1.91.

The obtained polymerization solution was reprecipitated and purified from a mixed solvent of methanol / water and vacuum dried to obtain block copolymer A. The molecular weights of the obtained block copolymer A were Mn67,100, Mw119,700, and Mw / Mn1.78 as measured by GPC (in terms of polystyrene). Table 1 also shows the charged block ratio (mass%). In Production Example 1, the ratio of each block of the polymer obtained in the first polymerization step and the second polymerization step is polymer block (A): polymer block (B) = 14:86 (mass ratio). As described above, the amount of monomer charged in each polymerization step was set.

<Production Examples 2, 5 to 7 and Comparative Production Examples 1, 2> Production of Polymers B, EG, I, J The types and amounts of raw materials to be charged into the flask are changed as shown in Table 1 and polymerized. The same operation as in Production Example 1 was carried out except that the temperature was appropriately adjusted to obtain polymers B, EG, I and J which are block copolymers. Table 2 shows the analysis results of the block composition and the molecular weight of the polymers B, E to G, I and J.

<Production Example 3> Production of Polymer C / First Polymerization Step (Production of Polymer Block (A))
61.5 parts of N-phenylmaleimide (hereinafter also referred to as "PhMI"), 38.5 parts of styrene (hereinafter also referred to as "St"), in a flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube. 2.29 parts of CBSTSP, 0.15 part of ABN-E, and 268 parts of acetonitrile were charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70 ° C. After 5 hours, the mixture was cooled to room temperature to terminate the polymerization. When the amount of residual monomer was measured by gas chromatography (GC) measurement and the monomer polymerization rate and block composition were calculated, each monomer polymerization rate was PhMI> 98% and St> 98%, and the block composition is shown in Table 2. It was as shown. When the molecular weight of the polymer was measured by GPC measurement (in terms of polystyrene), it was Mn7,900, Mw9,200, and Mw / Mn1.17.

-Second polymerization step (manufacturing of polymer block (B))
Next, 114 parts of MA, 266 parts of BA, 328 parts of MMA, 1.40 parts of ABN-E, and 267 parts of acetonitrile were charged, sufficiently degassed by nitrogen bubbling, and polymerization was restarted in a constant temperature bath at 80 ° C. After 5 hours, the mixture was cooled to room temperature to terminate the polymerization. When the amount of residual monomer was measured by gas chromatography (GC) measurement and the monomer polymerization rate and block composition were calculated, each monomer polymerization rate was MA85%, BA85%, MMA> 99%, and the block composition was shown in Table 2. It was as shown in. When the molecular weight of the block copolymer was measured by GPC measurement (in terms of polystyrene), it was Mn46,300, Mw82,600, and Mw / Mn1.78.

-Third polymerization step (manufacturing of polymer block (C))
Then, 7.41 parts of MA, 17.3 parts of BA, 115 parts of HEA, 0.46 parts of ABN-E, and 236 parts of acetonitrile were charged, sufficiently degassed by nitrogen bubbling, and the polymerization was restarted in a constant temperature bath at 70 ° C. After 5 hours, the mixture was cooled to room temperature to terminate the polymerization, and a solution containing a block copolymer (referred to as "polymer C") was obtained. When the amount of residual monomer was measured by gas chromatography (GC) measurement and the monomer polymerization rate and block composition were calculated, each monomer polymerization rate was 83% of MA (residual portion of the second polymerization step and additional portion of the third polymerization step). , BA (residual part of the second polymerization step and additional part of the third polymerization step) 76%, HEA 87%, and the block composition was as shown in Table 2. When the molecular weight of the block copolymer was measured by GPC measurement (in terms of polystyrene), it was Mn55,400, Mw119,200, and Mw / Mn2.15.

The obtained polymerization solution was reprecipitated and purified from a mixed solvent of methanol / water and vacuum dried to obtain a polymer C. The molecular weights of the obtained polymer C were Mn70,300, Mw132,100, and Mw / Mn1.88 as measured by GPC (in terms of polystyrene).

<Production Examples 4 and 8> Production of Polymers D and H The same operation as in Production Example 3 is performed except that the types and amounts of raw materials charged in the flask are changed as shown in Table 1 and the polymerization temperature is appropriately adjusted. This was carried out to obtain polymers D and H, which are block copolymers. Table 2 shows the analysis results of the block composition and the molecular weight of the polymers D and H.

Details of the compounds (monomer, control agent, initiator, solvent) shown in Tables 1 and 2 are as follows. For each monomer, the Tg of the homopolymer produced from the monomer is shown in parentheses. The homopolymer Tg is quoted from the National Institute for Materials Science, National Institute for Materials Science (https://polymer.nims.go.jp/). The Tg of the N-phenylmaleimide homopolymer uses Tg (221 ° C.) of the N-phenylmaleimide / styrene alternating copolymer (62.4 / 37.6 wt%) and Tg (98 ° C.) of the styrene homopolymer. The value calculated from the Fox formula was used.
MA: Methyl acrylate (10 ° C)
BA: n-butyl acrylate (-48 ° C)
EA: Ethyl acrylate (-21 ° C)
MMA: Methyl methacrylate (108 ° C)
HEA: 2-hydroxyethyl acrylate (-15 ° C)
PhMI: N-Phenylmaleimide (344 ° C)
St: Styrene (98 ° C)
ABN-E: 2,2'-azobis (2-methylbutyronitrile)
CBSTSP: 2-{[(2-carboxyethyl) sulfanylthiocarbonyl] sulfanyl} propanoic acid DBTTC: S, S-dibenzyltrithiocarbonate

2. 2. Evaluation <Examples 1 to 8 and Comparative Examples 1 and 2>
Each block copolymer (polymers A to J) produced above was used as a binder resin to prepare a slurry composition. In addition, a ceramic green sheet was produced and evaluated using the prepared slurry composition. The method for preparing the slurry composition and the evaluation items in Examples and Comparative Examples are as follows.

<Preparation of slurry composition>
As a ceramic powder, 100 parts of barium titanate with a particle diameter of 0.1 μm (“BT-01” manufactured by Sakai Chemical Industry Co., Ltd.), 1 part of a dispersant (“Marialim SC-0505K” manufactured by Nichiyu Co., Ltd.), and as a solvent. After stirring 56 parts of toluene and 14 parts of ethanol together with 100 parts of zirconia beads having a particle size of 0.1 mm at 500 rpm for 5 hours using a bead mill (“Easy Nano RMB” manufactured by IMEX Co., Ltd.), the zirconia beads are separated by filtration. Then, a barium titanate dispersion was prepared. To 171 parts of this dispersion, 10 parts of the binder resin and the amounts of toluene and ethanol shown in Table 3 were added, and then using a rotation / revolution mixer at 2000 rpm for 5 minutes. Stirring was performed to prepare a slurry composition.

<Pyrolytic property of binder resin>
Regarding the thermal decomposability of the binder resin, each binder resin was used as a sample, the temperature of the sample was raised to a predetermined temperature, and the mass residual ratio at the time when the temperature reached 500 ° C. was evaluated. Specifically, using a thermal analyzer (TGDTA6300 manufactured by Hitachi High-Tech Science Co., Ltd.), the temperature of 5 to 8 mg of the sample is raised from 30 ° C. to 600 ° C. at a heating rate of 10 ° C./min under a nitrogen gas flow. Then, the mass change during that period was measured, and the mass residual ratio at the time when the temperature reached 500 ° C. was determined.

<Viscosity measurement of slurry composition>
After adjusting the slurry composition obtained above to 25 ° C., the viscosity at a rotor rotation speed of 6 rpm was measured using a B-type viscometer.

<Tension characteristics of ceramic green sheet>
The slurry composition obtained above is coated on a release-treated PET film using a variable applicator so that the thickness of the green sheet after drying becomes 100 μm, and is placed in a ventilation dryer at 100 ° C. for 15 minutes. A ceramic green sheet was prepared by drying the above. A 4 cm × 1 cm test piece was cut out from the produced ceramic green sheet, and the tensile physical properties of the ceramic green sheet under normal conditions (25 ° C.) were measured with a tensile tester at a tensile speed of 10 mm / min. ), Maximum strength (MPa) and tensile volume (elongation at break (%) × maximum strength (MPa)) were determined.

Table 3 shows the block ratios of the polymers A to J, the Tg of each block, and the evaluation results of Examples 1 to 8 and Comparative Examples 1 and 2.

As shown in Table 3, the slurry compositions of Examples 1 to 8 containing the block copolymer (P) showed a low slurry viscosity of 1200 mPa · s or less. Further, the obtained ceramic green sheet had a high strength of 1.3 MPa or more, and showed sufficiently high values of elongation at break and tensile product. In particular, in Examples 1, 2, 5, 6 and 8, it was possible to obtain a ceramic green sheet having high strength, elongation at break and tensile product while having a low slurry viscosity of 500 mPa · s or less. Further, in Examples 2 to 5, the tensile strength was as high as 150 MPa ·% or more, and it was shown that the toughness was excellent. Further, in Examples 1 to 3 in which the methacrylic acid ester compound was introduced into the block copolymer (P), the thermal decomposability of the binder resin was also good.

On the other hand, in Comparative Examples 1 and 2 in which a (meth) acrylic block copolymer having no hydrogen-bonding functional group was used instead of the block copolymer (P), the viscosity of the slurry composition was 3000 mPa. It showed a high value of s or more. In addition, the strength and tensile strength of the obtained ceramic green sheet were lower than those of Examples 1 to 8.

From the above results, it was clarified that by using the block copolymer (P), it is possible to produce a ceramic green sheet having high strength and excellent thermal decomposability while keeping the viscosity of the ceramic slurry low.

The present disclosure has been described in accordance with the examples, but it is understood that the present disclosure is not limited to the examples. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms containing only one element, more, or less, are within the scope and scope of the present disclosure.

Claims (10)

A binder for producing ceramic green sheets containing block copolymers.
The block copolymer is a binder for producing a ceramic green sheet, which is mainly composed of a structural unit derived from a vinyl monomer, has substantially no polyvinyl acetal structure, and has a hydrogen-bonding functional group. The binder for producing a ceramic green sheet according to claim 1, wherein the block copolymer has a structural unit derived from a (meth) acrylic monomer in an amount of 70% by mass or more based on all the structural units. The binder for producing a ceramic green sheet according to claim 1 or 2, wherein the block copolymer has a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an imide group-containing vinyl monomer. .. The ceramic green sheet according to any one of claims 1 to 3, wherein the block copolymer has a structural unit derived from a methacrylic acid ester compound in an amount of 5% by mass or more and 70% by mass or less with respect to all the structural units. Binder for manufacturing. The block copolymer according to any one of claims 1 to 4, wherein the block copolymer has a polymer block having a glass transition temperature of 30 ° C. or higher and a polymer block having a glass transition temperature of less than 30 ° C. Binder for manufacturing ceramic green sheets. Any one of claims 1 to 5, wherein the block copolymer has 5% by mass or more and 25% by mass or less of structural units derived from a vinyl monomer having a hydrogen-bonding functional group with respect to all structural units. Binder for manufacturing the ceramic green sheet described in the section. Any of claims 1 to 6, wherein the block copolymer has a molecular weight distribution (Mw / Mn) represented by a ratio of a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 3.0 or less. The binder for producing a ceramic green sheet according to item 1. A slurry composition comprising the binder for producing a ceramic green sheet according to any one of claims 1 to 7 and a ceramic powder. A ceramic green sheet formed by using the slurry composition according to claim 8. A method for manufacturing a multilayer ceramic capacitor using the ceramic green sheet according to claim 9.