TW202202591A - Binder for producing ceramic green sheet, slurry composition, ceramic green sheet, and method for producing multilayer ceramic capacitors - Google Patents

Abstract

A binder for producing a ceramic green sheet contains a block copolymer that has a vinyl monomer-derived structural unit for main component thereof, has a hydrogen-bonding functional group, and substantially does not have a polyvinyl acetal structure. A slurry composition contains a ceramic powder and the binder for producing a ceramic green sheet that contains a block copolymer that has a vinyl monomer-derived structural unit for main component thereof, has a hydrogen-bonding functional group, and substantially does not have a polyvinyl acetal structure. A ceramic green sheet is formed using the slurry composition.

Description

Adhesive for manufacturing ceramic green sheets, slurry composition, ceramic green sheet and method for manufacturing multilayer ceramic capacitors

The present invention relates to an adhesive for the manufacture of ceramic green sheets, a slurry composition, a ceramic green sheet and a method for manufacturing a multilayer ceramic capacitor.

A multilayer ceramic capacitor is generally produced by laminating a ceramic green sheet formed by using a slurry composition containing a ceramic powder and a binder. When manufacturing a multilayer ceramic capacitor, first, a metal paste to be an internal electrode is printed on a ceramic green sheet, and then the green sheets are laminated, and then a layered body is manufactured by heat and pressure bonding. Next, by subjecting the layered body to a heat treatment (degreasing treatment), the binder resin contained in the layered body is thermally decomposed, and thereafter, high-temperature sintering is performed. External electrodes are formed on the ceramic sintered body thus obtained, and a multilayer ceramic capacitor can be obtained.

As a binder of a ceramic green sheet, a polyvinyl acetal resin or a (meth)acrylic resin is generally used (for example, refer to Patent Document 1 and Patent Document 2). Patent Document 1 discloses a slurry composition for ceramic green sheets containing a polyvinyl acetal resin of a specific composition as a binder. Moreover, in patent document 2, the slurry composition for ceramic green sheets containing the (meth)acrylic-type resin of a specific composition as a binder is disclosed. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2006-089354 [Patent Document 2] International Publication No. 2018/235907

[Technical problem to be solved by the invention]

In the case of using polyvinyl acetal resin as a binder, a relatively high-strength ceramic green sheet can be obtained. On the other hand, it is difficult to say that polyvinyl acetal resin has sufficiently high thermal decomposability, and there is generation after degreasing treatment. Concerns about adhesive residues.

On the other hand, although the (meth)acrylic resin exhibits good thermal decomposability, it is difficult to say that the obtained ceramic green sheet has sufficiently high strength. Therefore, in the manufacturing process of the multilayer ceramic capacitor, there is a concern that cracks or the like may be generated in the ceramic green sheet due to the load acting on the ceramic green sheet. Such cracks in the ceramic green sheets are more likely to occur in the thin film and multi-layered ceramic green sheets with the development of high-performance electronic devices.

The method of improving the strength of the ceramic green sheet can be considered to seek the high molecular weight of the adhesive. However, when a high molecular weight binder is used, the viscosity of the slurry composition for ceramic green sheets becomes high, and there is a concern that the coatability of the support decreases.

The present invention is made in view of the above-mentioned circumstances, and its main object is to provide an adhesive for the manufacture of ceramic green sheets, which can obtain a high-strength and excellent thermally decomposable adhesive while maintaining a low viscosity of a slurry composition. Ceramic embryos. [Technical means]

The present inventors have completed the present invention by using a specific block copolymer as a result of earnest studies in order to solve the above-mentioned problems. The following means are provided according to the present invention.

[1] An adhesive for the manufacture of a ceramic green sheet, which is an adhesive for the manufacture of a ceramic green sheet containing a block copolymer, characterized in that the aforementioned block copolymer contains a structural unit derived from a vinyl monomer as a The main body has substantially no polyvinyl acetal structure and has a hydrogen-bonding functional group. [2] The binder for producing a ceramic green sheet according to [1], wherein the block copolymer has 70% by mass or more of structural units derived from (meth)acrylic monomers with respect to all the structural units. [3] The binder for producing ceramic green sheets according to [1] or [2], wherein the block copolymer has a structural unit derived from an aromatic vinyl monomer and a The structural unit of the vinyl monomer. [4] The binder for producing a ceramic green sheet according to any one of [1] to [3], wherein the block copolymer has 5% by mass to 70% by mass of methyl alcohol relative to all structural units Structural unit of acrylic acid ester compound. [5] The binder for producing ceramic green sheets according to any one of [1] to [4], wherein the block copolymer has a polymer block having a glass transition temperature of 30° C. or higher and a glass transition temperature It is a polymer block below 30°C.

[6] The binder for producing ceramic green sheets according to any one of [1] to [5], wherein the block copolymer has 5 mass % or more and 25 mass % or less with respect to all the structural units. Structural unit of vinyl monomer with hydrogen bonding functional group. [7] The binder for producing ceramic green sheets according to any one of [1] to [6], wherein the block copolymer is represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) The molecular weight distribution (Mw/Mn) is 3.0 or less. [8] A slurry composition characterized by comprising: 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 characterized by being formed using the slurry composition of the above-mentioned [8]. [10] A method of manufacturing a multilayer ceramic capacitor, characterized by using the ceramic green sheet of the above [9]. [Effect of invention]

According to the adhesive for producing ceramic green sheets of the present invention, a ceramic green sheet having high strength and excellent thermal decomposability can be obtained while maintaining a low viscosity of the slurry composition.

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

"Binder for the manufacture of ceramic blanks" The adhesive for producing ceramic green sheets of the present invention is used for forming ceramic powders to produce laminated ceramic green sheets. The adhesive for producing ceramic green sheets of the present invention contains a block copolymer (hereinafter also referred to as "block copolymer (P)"); the block copolymer contains structural units derived from vinyl monomers as The main body has substantially no polyvinyl acetal structure and has a hydrogen-bonding functional group.

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

In addition, in this specification, "contains the structural unit derived from the vinyl monomer as the main body" means the content ratio of the structural unit derived from the vinyl monomer in the block copolymer (P) relative to the block copolymer (P). The total structural unit of the copolymer (P) is 80 mass % or more, preferably 90 mass % or more, more preferably 95 mass % or more, and particularly preferably 99 mass % or more.

(Meth)acrylic monomers include (meth)acrylic acid, (meth)acrylic acid alkyl ester compounds, (meth)acrylic acid alicyclic ester compounds, (meth)acrylic acid aromatic esters Compounds, (meth)acrylic acid alkoxyalkyl compounds, (meth)acrylic acid hydroxyalkyl compounds, (di) alkylaminoalkyl (meth)acrylate compounds, epoxy group-containing (methyl) compounds Acrylate compounds, polyoxyalkylene (meth)acrylate compounds, and the like.

As specific examples of these, alkyl (meth)acrylate compounds: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, (meth)acrylate Isopropyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, pentyl (meth)acrylate ester, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-decyl (meth)acrylate, etc.; Alicyclic ester compounds of (meth)acrylic acid: cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, (meth)acrylate Cyclododecyl acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate and dicyclopentadienyl (meth)acrylate, etc.; Aromatic ester compounds of (meth)acrylic acid: phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate and ( 3-phenoxypropyl meth)acrylate, etc.; (Meth)acrylate alkoxyalkyl compounds: (meth)acrylate methoxymethyl, (meth)acrylate ethoxymethyl, (meth)acrylate methoxyethyl, (meth)acrylate ethoxyethyl Esters, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, and ethoxypropyl (meth)acrylate, etc.; (Meth)acrylic acid hydroxyalkyl compounds: (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl and (meth)acrylic acid 4-hydroxybutyl, etc.; (Di) Alkylaminoalkyl (meth)acrylate compounds: N-[2-(methylamino)ethyl](meth)acrylate, N-[2-(dimethylamino)ethyl ](meth)acrylate, N-[2-(ethylamino)ethyl](meth)acrylate and N-[2-(diethylamino)ethyl](meth)acrylate, etc.; (Meth)acrylate compound containing epoxy group: glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether and 3,4-epoxycyclohexylmethyl (methyl) ) acrylate, etc.; Polyoxyalkylene (meth)acrylate compound: polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, and the like. The (meth)acrylic monomers can be used alone or in combination of two or more.

The (meth)acrylic monomer used in the production of the block copolymer (P) is used as a binder for the production of ceramic green sheets because of its high thermal decomposability during firing and the ability to reduce the cost of the binder. From the viewpoint of the residue, among the above, a compound represented by the following formula (1) is preferred. CH ₂ =CR ¹ -C(=O)-O-(R ² O) _n -R ³ ...(1) (In formula (1), R ¹ is a hydrogen atom or a methyl group, and R ² is a carbon number of 2~ Linear or branched alkyl group of 6, R ³ is a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, or a carbon Aralkyl groups of 7 to 20. n is an integer of 0 to 50. When n is 2 or more, the plural R ² in the formula may be the same or different from each other.)

From the viewpoint that the dispersion stability of the ceramic powder can be further improved, the (meth)acrylic monomer used in the production of the block copolymer (P) preferably contains an alkyl (meth)acrylate compound . Particularly preferred among these is selected from methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-(meth)acrylate - At least one of the group consisting of butyl ester, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

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 acid unit in the block copolymer (P) is preferably 70% by mass or more with respect to all the structural units of the block copolymer (P). By making the block copolymer (P) contain 70 mass % or more of (meth)acrylic acid units, it is suitable to be able to form a binder resin excellent in thermal decomposability at the time of firing. From such a viewpoint, the content ratio of the (meth)acrylic acid unit is more preferably 80% by mass or more, more preferably 85% by mass, and particularly preferably 80% by mass or more with respect to all the structural units of the block copolymer (P). It is 87 mass %.

The block copolymer (P) preferably has a structural unit derived from a methacrylate compound (hereinafter also referred to as "methacrylate unit"). By making the block copolymer (P) have a methacrylate unit, it is suitable for the feature that the thermal decomposability of the adhesive can be further improved. The methacrylate unit is preferably a structural unit derived from a compound represented by the following formula (2). CH ₂ =C(CH ₃ )-C(=O)-O-(R ⁴ O) _m -R ⁵ …(2) (In formula (2), R ⁴ is a straight chain with 2 to 6 carbon atoms or Branched alkyl group, R ⁵ is a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, or an aryl group with 7 to 20 carbon atoms. Alkyl. m is an integer from 0 to 50. When m is 2 or more, the plural R ⁴ in the formula can be the same or different from each other.)

Specific examples of the compound represented by the above formula (2) include alkyl methacrylate compounds, aliphatic cyclic ester compounds of methacrylic acid, exemplified by vinyl monomers constituting the block copolymer (P), Aromatic ester compounds of methacrylic acid, alkoxyalkyl methacrylate compounds, hydroxyalkyl methacrylate compounds, polyoxyalkylene methacrylate compounds, and the like.

Among the above, the methacrylate units contained in the block copolymer (P) are preferably derived from the group consisting of alkyl methacrylate compounds, alkoxyalkyl methacrylate compounds, and hydroxyalkane methacrylates. At least one structural unit in the group consisting of a base compound and a polyoxyalkylene methacrylate compound, more preferably derived from the group consisting of an alkyl methacrylate compound, an alkoxyalkyl methacrylate compound, and at least one structural unit in the group of methacrylic acid hydroxyalkyl compounds. Among these, it is particularly preferable that the block copolymer (P) has a structural unit derived from at least one kind selected from the group consisting of an alkyl methacrylate compound and an alkoxyalkyl methacrylate compound.

The content ratio of the methacrylate units in the block copolymer (P) is preferably 3% by mass or more, more preferably 5% by mass or more, based on the total structural units of the block copolymer (P), and further More preferably, it is 10 mass % or more. The upper limit of the content ratio of the methacrylate unit is preferably 70% by mass or less with respect to all the structural units of the block copolymer (P) from the viewpoint of suppressing the decrease in strength and flexibility of the ceramic green sheet , more preferably 65 mass % or less, further more preferably 60 mass % or less. In addition, methacrylate compounds may be used alone or in combination of two or more.

A block copolymer (P) having 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 also referred to as "imide group-containing vinyl unit"), it is suitable for the feature that the strength of the ceramic green sheet produced by using the block copolymer (P) can be further improved.

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

Examples of vinyl monomers containing an imide group include maleimide compounds such as maleimide and N-substituted maleimide compounds; N-methylitaconimide (itaconimide) , N-ethyl itaconimide, N-butyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide, etc. Compounds; N-methyl citraconimide, N-ethyl citraconimide, N-butyl citraconimide, N-2-ethylhexyl citraconimide, N- Citraconimide compounds such as cyclohexyl citraconimide; N-(2-(meth)acryloyloxyethyl)succinimide, N-(2-(meth)acryloyloxy) ethyl) maleimide, N-(2-(meth)acryloyloxyethyl)phthalimide, N-(4-(meth)acryloyloxybutyl) (meth)acrylic imide compounds such as imide phthalate and the like. Among these, maleimide compounds are preferred from the viewpoint of exhibiting high copolymerizability with styrene-based monomers.

As the maleimide compound, maleimide and N-substituted maleimide compounds can be preferably used. N-substituted maleimide compounds include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide Imide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-pentylmaleimide, N-hexyl N-maleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide, etc. Alkyl-substituted maleimide compounds; N-cycloalkyl-substituted maleimide compounds such as N-cyclopentylmaleimide and N-cyclohexylmaleimide; N-benzylmaleimide N-aralkyl substituted maleimide compounds such as lyimide; N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-ethyl) Acetylphenyl)maleimide, N-(4-methoxyphenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(4-chloro N-aryl-substituted maleimide compounds such as phenyl) maleimide, N-(4-bromophenyl) maleimide, and the like. In addition, as the vinyl monomer containing imide, one or more of these can be used.

（式(3)中，R⁶ 表示氫原子、碳數1~3之烷基、環己基、苯基、或者於苯基之任意位置之羥基、碳數1~2之烷氧基、乙醯基或鍵結鹵素原子之取代苯基。）Among the above-mentioned vinyl monomers containing imide used for the production of the block copolymer (P), a compound represented by the following formula (3) is preferred. [Change 1]

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

When the block copolymer (P) has an aromatic vinyl unit, the content ratio of the aromatic vinyl unit is preferably 0.5 mass % or more with respect to all the structural units of the block copolymer (P), more preferably It is 1 mass % or more, More preferably, it is 2 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, and 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 vinyl units containing imide, the content ratio of the vinyl units containing imide is preferably 0.5 with respect to all the structural units of the block copolymer (P). It is at least 1 mass %, more preferably at least 1 mass %, and still more preferably at least 2 mass %. The upper limit of the vinyl unit containing imide is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass based on the total structural units of the block copolymer (P). the following. In addition, in the case where an aromatic vinyl monomer and an imide-containing vinyl monomer are used in combination in the production of the block copolymer (P), the amount of the aromatic vinyl is 1 mol relative to 1 mol of the imide-containing vinyl. The use ratio of the base monomer is preferably 0.01-20 mol, more preferably 0.1-10 mol, and still more preferably 0.2-5 mol.

As long as the block copolymer (P) does not interfere with the effect of the present invention, it may also have other than (meth)acrylic monomers, aromatic vinyl monomers and vinyl monomers containing imide. Structural units of vinyl monomers (hereinafter also referred to as "other vinyl monomers"). Examples of other vinyl monomers include (meth)acrylamide compounds such as (meth)acrylamide, tert-butyl (meth)acrylamide, and N-methylol acrylamide; acetic acid Vinyl ester, vinyl benzoate, etc. The content ratio of structural units derived from other vinyl monomers in the block copolymer (P) is preferably 5% by mass or less, more preferably 3% by mass relative to the total structural units of the block copolymer (P). It is less than or equal to 1 mass %, more preferably less than or equal to 1 mass %, and particularly preferably less than or equal to 0.5 mass %.

(Hydrogen bonding functional group) The block copolymer (P) has a hydrogen-bonding functional group. The block copolymer (P) has hydrogen-bonding functional groups, such as hydroxyl, amine group (including primary, secondary and tertiary amino groups), carboxyl group, amide group, thiol group, Sulfonyl etc. Among these, a hydroxyl group, an amino group, and a carboxyl group are preferred, and a hydroxyl group is particularly preferred, from the viewpoint of having high adsorption to the ceramic powder and improving the dispersion stability of the ceramic powder.

The block copolymer (P) is preferably a It is produced using a vinyl monomer having a hydrogen-bonding functional group (hereinafter also referred to as a "hydrogen-bonding group-containing vinyl monomer"). The vinyl monomer containing a hydrogen-bonding group preferably has a hydroxyl group, and specific examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and (methyl) (Meth)acrylic hydroxyalkyl compounds such as 3-hydroxypropyl acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate ; Mono(meth)acrylate compounds of polyalkylene glycols (polyethylene glycol, polypropylene glycol, etc.); p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenyl Hydroxystyrene compounds such as phenol, m-isopropenylphenol and o-isopropenylphenol; hydroxy-substituted maleimide compounds such as N-(4-hydroxyphenyl)maleimide, etc. Among the above-mentioned vinyl monomers containing a hydrogen-bonding group, it is particularly preferable to use a (meth)acrylic acid hydroxyalkyl compound.

In the block copolymer (P), the content ratio of the structural unit derived from the hydrogen-bonding group-containing vinyl monomer is higher than that of the block copolymer ( The total structural unit of P) is preferably 5 mass % or more, more preferably 7 mass % or more, and still more preferably 8 mass % or more. Regarding the upper limit of the content ratio of the structural unit derived from the hydrogen-bonding group-containing vinyl monomer, from the viewpoint of ensuring the solubility to the solvent component of the slurry composition, the content of the block copolymer (P) is The total structural unit is preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less. Moreover, as for the vinyl monomer containing a hydrogen bondable group, only 1 type may be used, and 2 or more types may be used together.

The block copolymer (P) is a polymer mainly composed of a (meth)acrylic acid unit, and does not substantially have a polyvinyl acetal structure. Here, in this specification, "does not have a polyvinyl acetal structure substantially" means that the block copolymer (P) does not exhibit characteristics derived from the polyvinyl acetal structure. However, the block copolymer (P) can be tolerated to have a small amount of polyvinyl acetal structure to the extent that the effect of the present invention is not hindered. Specifically, the ratio of the polyvinyl acetal structure in the block copolymer (P) is typically 2 mass % or less, preferably 1 mass % or less, more preferably 0.5 mass % or less, still more preferably It is 0.1 mass % or less, and it is especially preferable that it 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 or arrangement order of the polymer blocks in one molecule is not particularly limited. Specific examples of the block copolymer (P) include, for example, a (AB) diblock composed of a polymer block (A) and a polymer block (B), a polymer block (A) composed of / polymer block (B) / (ABA) triblock composed of polymer block (A), polymer block (A) and polymer block (B) and polymer block (C) ) composed of (ABC) triblocks, etc. In addition, the block copolymer (P) may be a polyblock copolymer having four or more polymer blocks. Among these, the number of polymer blocks per molecule of the block copolymer (P) from the viewpoint of efficiently producing a slurry composition of ceramic powder with high dispersion stability and sufficiently low viscosity , preferably 2 or more and 7 or less, more preferably 2 or more and 5 or less, still more preferably 2 or 3.

The block copolymer (P) may have at least two polymer blocks, all of which may have hydrogen-bonding functional groups, or may be only a part of the two or more polymer blocks. Has a hydrogen-bonding functional group. From the viewpoint of sufficiently improving the dispersion stability of the ceramic powder, the block copolymer (P) preferably has at least two polymer blocks that satisfy the following [i] or [ii]. [i] Among 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-bondable functional groups, and the content ratio of the structural unit derived from the hydrogen-bondable group-containing vinyl monomer differs among the polymer blocks.

Each polymer block of the block copolymer (P) is mainly composed of structural units derived from vinyl monomers. A preferred aspect is a block copolymer (P) having a polymer block (hereinafter also referred to as a "hard segment") with a glass transition temperature (Tg) of 30°C or higher, and a Tg A polymer block (hereinafter also referred to as a "soft segment") at a temperature of 30°C. According to this aspect, the block copolymer (P) can obtain a polymer capable of forming a pseudo-crosslinked structure by forming a microphase-separated structure or the like. In addition, the ceramic green sheet produced by using such a block copolymer (P) is characterized in that the breaking energy can be increased while maintaining the low viscosity of the slurry, and the mechanical properties can be improved. suitable.

The Tg of the hard segment is preferably 50°C or higher, more preferably 75°C or higher, and still more preferably 100°C or higher. In addition, the Tg of the hard segment is generally 250°C or lower due to the restriction of the monomer used as the 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 even more preferably 100°C or higher and 250°C or lower. In this specification, the glass transition temperature (Tg) of the polymer block is a value calculated by the formula of Fox as described in the examples described later.

The Tg of the soft segment is preferably 25°C or lower, more preferably 20°C or lower, and still more preferably 10°C or lower. In addition, the Tg of the soft segment is preferably -50°C or higher, more preferably -30°C or higher, and still more preferably -20°C or higher. The range of Tg of the soft segment is preferably -50°C or more and less than 30°C, more preferably -30°C or more and less than 30°C, still more preferably -20°C or more and less than 30°C.

The mass ratio of the hard segment in the block copolymer (P) is preferably 3 mass % or more, more preferably 5 mass %, from the viewpoint that a pseudo-crosslinked structure can be formed by the formation of a microphase-separated structure or the like % by mass or more, more preferably 10% by mass or more. In addition, the upper limit of the mass ratio is preferably 50 mass % or less, more preferably 35 mass % or less, 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. Preferably it is 20 mass % or less. In addition, the mass ratio of the hard segments in the block copolymer (P) is determined by the input ratio of each block when the block copolymer (P) is produced (hereinafter also referred to as "input 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, the hard segment is preferably a polymer block containing an aromatic vinyl unit and an imide-containing vinyl unit. A segment with a sufficiently high glass transition temperature can be formed by a polymer block having an aromatic vinyl unit and an imide-containing vinyl unit, and a structure by microphase separation can be easily produced The characteristics of the polymer that can form a pseudo-crosslinked structure, etc., are preferred. The polymer block is preferably a polymer block having an aromatic vinyl unit and a structural unit derived from a maleimide compound, more preferably a structural unit derived from a styrene monomer, and a source A polymer block in the structural unit of maleimide. In the polymer block, the content ratio of the total of the aromatic vinyl unit and the imide group-containing vinyl unit is preferably 40 mass % or more, more preferably 50 mass % or more, and still more preferably 55 mass % %above.

Preferred embodiments of the block structure of the block copolymer (P) include the following aspects [1] and [2]. [1] A block copolymer comprising a first block mainly composed of a (meth)acrylic unit, and a second block composed mainly of a (meth)acrylic unit and having a monomer composition different from that of the first block block. [2] A block copolymer comprising a polymer block containing a (meth)acrylic acid unit as a main body, 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 block copolymer comprising a first block mainly composed of a (meth)acrylic acid unit, and a second block composed mainly of a (meth)acrylic acid unit, and the first block and One of the second blocks has a hydrogen-bonding functional group, and the other does not have a hydrogen-bonding functional group. [1-2] A block copolymer comprising a first block mainly composed of a (meth)acrylic acid unit, and a second block composed mainly of a (meth)acrylic acid unit, and the first block and Each of the second blocks has a hydrogen-bonding functional group, and the content ratio of the structural unit derived from the hydrogen-bonding group-containing vinyl monomer differs 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 block copolymer comprising a polymer block containing a (meth)acrylic acid unit as a main body, and a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit , and one of these polymer blocks has a hydrogen-bonding functional group, and the other does not have a hydrogen-bonding functional group. [2-2] A block copolymer comprising a polymer block having a (meth)acrylic acid unit as a main body, and a polymer block having an aromatic vinyl unit and an imide group-containing vinyl unit , and these polymer blocks all have hydrogen-bonding functional groups, and the content ratio of structural units derived from vinyl monomers containing hydrogen-bonding groups varies among polymer blocks.

For the block copolymer (P), the polyethylene-converted 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, it is preferable that the strength of the ceramic green sheet produced by using the block copolymer (P) can be sufficiently improved. In addition, when Mn is 500,000 or less, the viscosity of the slurry composition can be suppressed from becoming too high, and the characteristics of coating properties and handling properties can be sufficiently ensured. 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. Moreover, Mn of the block copolymer (P) is more preferably 300,000 or less, still more preferably 250,000 or less, and particularly preferably 150,000 or less.

For the block copolymer (P), the weight average molecular weight (Mw) in terms of polyethylene measured by gel permeation chromatography (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, still more preferably 50,000 or more, and particularly preferably 70,000 or more. Moreover, Mw of the block copolymer (P) is more preferably 500,000 or less, still more preferably 300,000 or less, and particularly preferably 250,000 or less.

In the block copolymer (P), the molecular weight distribution (Mw/Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) can suppress the slurry containing the block copolymer (P) From a viewpoint that the viscosity of a composition becomes too high, it is preferable that it is 3.0 or less. In addition, when Mw/Mn is 3.0 or less, since 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 reduced, the block copolymer (P) can be obtained. High molecular weight. Therefore, the strength of the ceramic green sheet obtained by using the slurry composition can be improved. 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 value of Mw/Mn is preferably 1.1 or more from the viewpoint of ease of manufacture.

<Production of block copolymer (P)> The block copolymer (P) is preferably produced by polymerizing the above-mentioned monomers by a living radical polymerization method, from the viewpoint that a block copolymer (P) having a sufficiently small molecular weight distribution can be obtained. For example, in the case of a solution polymerization method, by adding an organic solvent and a monomer into a reactor, and adding a polymerization control agent and a radical polymerization initiator, preferably heating and copolymerization, the target block copolymerization can be obtained. thing (P). The input method of each raw material may be a batch type initial one-time input of all the raw materials at one time, a semi-continuous input of continuously supplying at least a part of the raw materials to the reactor, or a batch of all the raw materials. A continuous polymerization mode in which the product is continuously supplied and simultaneously withdrawn from the reactor.

In the production of the block copolymer (P), a known polymerization method can be used as the living radical polymerization method. Specific examples of the living radical polymerization method to be used include a living radical polymerization method of an exchange chain transfer mechanism, a living radical polymerization method of a bond dissociation mechanism, and a living radical polymerization method of an atom transfer mechanism. Specific examples of these include, individually, living radical polymerization methods using an exchange chain transfer mechanism: reversible addition-fragmentation chain transfer polymerization (RAFT method), iodine transfer polymerization, and polymerization using an organic tellurium compound (TERP method) ), the polymerization method using organic antimony compounds (SBRP method), the polymerization method using organic bismuth compounds (BIRP method), etc.; the living radical polymerization method of bond dissociation mechanism: nitroxide radical method (NMP method), etc.; atom transfer Mechanism: Atom Transfer Radical Polymerization (ATRP), etc. Among them, from the viewpoint of being applicable to the widest range of vinyl monomers and having excellent polymerization controllability, the living radical polymerization method of the exchange chain transfer mechanism is preferred; from the viewpoint of ease of implementation In particular, the RAFT method is particularly preferred.

In the RAFT method, polymerization is carried out 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 conventional RAFT agents such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds can be used. As the RAFT agent, a monofunctional compound having only one active site or a polyfunctional compound having two or more active sites may be used. In the manufacture of block copolymers of A-(BA)n-type structure, B-(AB)n-type structure, or (AB)mC-(BA)n-type structure (wherein, n and m are integers of 1 or more) In this case, it is preferable to use a bifunctional RAFT agent from the viewpoint of easily and efficiently obtaining the block copolymer. The amount of 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, conventional radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used. Among these, an azo compound is preferable from the viewpoint of being easy to handle safely and hardly generating side reactions at the time of radical polymerization. Specific examples of the azo compound include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis 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-methyl Propionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), etc. As a radical polymerization initiator, only 1 type may be used and 2 or more types may be used together.

The amount of the radical polymerization initiator to be used is not particularly limited, but from the viewpoint of obtaining a polymer with a smaller molecular weight distribution, it is preferably 1 part by mass or less, more preferably 0.8 mass part, relative to 1 part by mass of the RAFT agent copies or less. From the viewpoint of stably advancing the polymerization reaction, the lower limit of the amount of the radical polymerization initiator used is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, relative to 1 part by mass of the RAFT agent. The usage amount of the radical polymerization initiator relative 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 still more preferably 50°C or higher and 80°C or lower. If the reaction temperature is 40°C or higher, the polymerization reaction can proceed smoothly, and if the reaction temperature is 100°C or lower, the side reactions can be suppressed and the influence on the usable initiator and solvent can be reduced. Restricted features are better. The reaction time can be appropriately set according to 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 can also be carried out in the presence of a chain transfer agent (eg, an alkylthiol compound having 2 to 20 carbon atoms, etc.) as required.

For example, in the case of obtaining a diblock copolymer composed of polymer block (A)-polymer block (B) by RAFT polymerization, the specific polymerization method can be exemplified by using a monofunctional RAFT agent A method for producing the desired diblock copolymer by sequentially polymerizing each block. In this method, first, in the first polymerization step, in the presence of a monofunctional RAFT agent and a radical polymerization initiator, a monomer is polymerized to obtain a polymer block (A). Next, in the second polymerization step, in the presence of the polymer block (A), the monomer is polymerized to obtain the polymer block (A)—the polymer block (B). In this way, a block copolymer (P) having two blocks can be obtained. Moreover, by repeating the above-mentioned polymerization process, the block copolymer (P) whose block number is 3 or more can be manufactured. For example, after the polymer block (A)-polymer block (B) is obtained by the first polymerization step and the second production step, by adding the polymer block (A)-polymer block (B) In the presence of polymerizing monomers, a triblock copolymer consisting of polymer block (A)-polymer block (B)-polymer block (C) can be obtained, or by polymer block (A) ─Polymer block (B)─A triblock copolymer composed of polymer block (A).

In addition, a block copolymer having a block number of 5 is obtained by RAFT polymerization from polymer block (A)-polymer block (B)-polymer block (C)-polymer block ( B)—In the case of a five-block copolymer composed of polymer blocks (A), the production method thereof, in addition to the method of sequentially polymerizing each block using the monofunctional RAFT agent as described above, can be exemplified by the following methods: A method for producing the target pentablock copolymer by performing three-stage polymerization using a difunctional RAFT agent. In this method, first, the first polymerization step is carried out in a bifunctional RAFT agent (for example: 1,4-bis(n-dodecylsulfanylthiocarbonylsulfanylmethyl)benzene, S, In the presence of S-dibenzyl trithiocarbonate, etc.) and a radical polymerization initiator, the monomer is polymerized to obtain the polymer block (A). Next, in the second polymerization step, in the presence of the polymer block (A), the monomer is polymerized to obtain the polymer block (A)→polymer block (B)→polymer block (A) ). Further, the third polymerization step is to polymerize monomers in the presence of polymer block (A)-polymer block (B)-polymer block (A), thereby obtaining a polymer block ( A)-polymer block (B)-polymer block (C)-polymer block (B)-polymer block (A) constitutes a five-block copolymer. The method of using a bifunctional RAFT agent is suitable because the simplification of the production steps can be achieved and the production efficiency can be improved.

In the production of the block copolymer (P), a known polymerization solvent can be used in the 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; and ketone compounds such as acetone and methyl ethyl ketone can be mentioned. ; Dimethylformamide, acetonitrile, dimethylsulfoxide, ethanol, water, etc. When the block copolymer (P) is produced by the solution polymerization method, the block copolymer (P) dissolved in the polymerization solvent can be dried by a conventional desolvation method such as a reprecipitation method, and a heat treatment or the like. method separately. In addition, it is also possible to carry out in the form of bulk polymerization or the like without using a polymerization solution.

"Slurry Composition" The slurry composition of the present invention is a polymer composition used in the manufacture of ceramic green sheets, and includes a block copolymer (P) and ceramic powder. As the ceramic powder, conventional materials for forming the dielectric layer of ceramic capacitors can be used, for example, barium titanate, titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, aluminum silicate, silicon nitride, etc. Dielectric powder. The content of the block copolymer (P) in the slurry composition is preferably 1 to 70 parts by mass, more preferably 3 to 50 parts by mass, relative to 100 parts by mass of the ceramic powder.

To the above-mentioned slurry composition, a solvent may be added if necessary. The solvent, preferably an organic solvent, includes hydrocarbons such as toluene, xylene, methylcyclohexane, terpineol, and the like; alcohols such as ethanol, n-propanol, isopropanol, and n-butanol. ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, etc.; ethyl acetate, butyl acetate, isobutyl acetate , propylene glycol monomethyl ether acetate and other esters. A solvent can be used individually by 1 type or in combination of 2 or more types. The content of the solvent in the slurry composition is preferably 10 to 500 parts by mass, more preferably 30 to 200 parts by mass, relative to 100 parts by mass of the ceramic powder.

In the slurry composition, in addition to the block copolymer (P), ceramic powder and solvent, conventional additives such as plasticizer, dispersant, leveling agent, defoamer, etc. can also be added . The addition ratio of these can be appropriately set according to each additive within the range that does not impair the effect of the present invention. The preparation of the slurry composition can be performed, for example, by mixing ceramic powder, a binder, a solvent if necessary, and the like using a bead mill.

The viscosity of the slurry composition is preferably 80 mPa･s or more, more preferably 100 mPa･s or more. By setting the viscosity of the slurry to be 80 mPa·s or more, the shape of the film can be secured when the slurry composition is applied on 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. In addition, the viscosity of the slurry composition was a value measured at 25° C. using a B-type viscometer with a rotor rotational speed set to 6 rpm.

"Ceramic Chips and Multilayer Ceramic Capacitors" The ceramic green sheet of the present invention is produced using a slurry composition containing the block copolymer (P) and ceramic powder. Furthermore, by laminating the obtained ceramic green sheets, a multilayer ceramic capacitor in which a dielectric layer is formed from the above-mentioned slurry composition can be produced. The method of manufacturing a ceramic green sheet and a multilayer ceramic capacitor is not particularly limited, and can be performed by a known method.

Specifically, first, a slurry composition containing the block copolymer (P) and ceramic powder is applied on a support such as PET that has been released from the mold. Next, the volatile components are removed from the slurry composition on the support by a drying process to form a film, and a ceramic green sheet is obtained. On this ceramic green sheet, a metal paste serving as an internal electrode is printed and dried, and the electrode-attached ceramic green sheet is peeled off from the support. A laminated body is produced by laminating the plurality of sheets and thermocompression bonding, and cutting the laminated body into a predetermined shape to obtain a ceramic green sheet. The ceramic green sheets obtained by heat treatment are degreasing (thermal decomposition of the binder), and then the ceramics are sintered at high temperature. In this way, a multilayer ceramic capacitor was obtained. [Example]

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, the following "parts" and "%" mean "mass parts" and "mass %", respectively, unless otherwise specified. The analysis method of the polymer obtained by 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 values of Mn and Mw. ○ Measurement conditions Column: TSKgel SuperMultiporeHZ-M manufactured by Tosoh Corporation x 4 Solvent: Tetrahydrofuran Temperature: 40°C Detector: RI Flow rate: 600μL/min

<Glass transition temperature (Tg)> The glass transition temperature (Tg) of the polymer block is based on the glass transition temperature of the homopolymer of each monomer constituting the polymer block, and is represented by the following formula (4) The Fox formula is calculated. 1/Tg=(W ₁ /Tg ₁ )+(W ₂ /Tg ₂ )+････+(W _n /Tg _n ) …(4) In addition, equation (4) is the object of calculation of Tg The calculation formula of the case where the polymer 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 represent the mass fraction of each monomer in the polymer block; Tg ₁ , Tg ₂ , ... and Tg _n represent the mass fraction of each monomer. Glass transition temperature of homopolymer (unit: K).

1. Manufacture of block copolymers <Production Example 1> Production of Polymer A ・1st polymerization step (production of polymer block (A)) 19.5 parts of methyl acrylate (hereinafter also referred to as "MA") and 10.5 parts of n-butyl acrylate (hereinafter also referred to as "BA") were put into a flask equipped with a stirrer, a thermometer, a reflux cooler and a nitrogen introduction tube. , 2-hydroxyethyl acrylate (hereinafter also referred to as "HEA") 70 parts, 2-{[(2-carboxyethyl)thiocarbonyl]sulfanyl}propionic acid (hereinafter also referred to as "CBSTSP") 1.60 parts, 0.14 parts of 2,2'-azobis(2-methylbutyronitrile) (hereinafter also referred to as "ABN-E"), and 184 parts of acetonitrile, fully degassed with nitrogen bubbling, and heated at 70°C The thermostat starts to polymerize. After 5 hours, the polymerization was stopped by cooling to room temperature. The residual monomer amount was measured and measured by gas chromatography (GC), and the results of the monomer polymerization rate and block composition were calculated. The polymerization rate of each monomer was MA38%, BA33%, HEA42%, and the block composition was shown in Table 2. Show. In addition, the block composition is calculated from the monomer polymerization rate (the same applies hereinafter). As a result of measuring the molecular weight of the polymer by GPC measurement (in terms of polystyrene), Mn was 5,600, Mw was 6,100, and Mw/Mn was 1.08.

・Second polymerization step (production of polymer block (B)) Next, 90 parts of MA, 210 parts of BA, 300 parts of methyl methacrylate (hereinafter also referred to as "MMA"), 1.20 parts of ABN-E, and 280 parts of acetonitrile were put in, fully degassed with nitrogen bubbling, and added to 80 parts of ℃ thermostat starts to polymerize again. After 5 hours, the polymerization was stopped by cooling to room temperature, and a solution containing a block copolymer (this was referred to as "polymer A") was obtained. The amount of residual monomers was measured and measured by gas chromatography (GC), and the results of the monomer polymerization rate and block composition were calculated. The polymerization rate of each monomer was MA (the remaining part in the first polymerization step and the additional part in the second polymerization step) 88%, BA (the remaining part of the first polymerization step and the additional part of the second polymerization step) 87%, MMA>99%, HEA (the remaining part of the first polymerization step) 90%, and the block composition is shown in Table 2. As a result of measuring the molecular weight of the block copolymer by GPC measurement (in terms of polystyrene), Mn was 60,000, Mw was 114,800, and Mw/Mn was 1.91.

The block copolymer A was obtained by reprecipitation and purification of the obtained polymerization solution from a methanol/water mixed solvent and vacuum drying. The molecular weight of the obtained block copolymer A was measured by GPC (in terms of polystyrene), Mn was 67,100, Mw was 119,700, and Mw/Mn was 1.78. In addition, the input block ratio (mass %) is collectively shown in Table 1. In Production Example 1, the ratio of each block contained in the polymer obtained in the first polymerization step and the second polymerization step was such that polymer block (A):polymer block (B)=14:86 (mass) ratio) to set the amount of monomer input in each polymerization step.

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

<Production Example 3> Production of Polymer C ・1st polymerization step (production of polymer block (A)) Into a flask equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen introduction tube, 61.5 parts of N-phenylmaleimide (hereinafter also referred to as "PhMI"), styrene (hereinafter also referred to as "St") were placed ) 38.5 parts, 2.29 parts of CBSTSP, 0.15 parts of ABN-E, and 268 parts of acetonitrile, fully degassed with nitrogen bubbling, and started to polymerize in a constant temperature bath at 70°C. After 5 hours, the polymerization was stopped by cooling to room temperature. The residual monomer amount was measured and measured by gas chromatography (GC), and the results of the monomer polymerization rate and block composition were calculated. The polymerization rate of each monomer was PhMI>98%, St>98%, and the block composition is shown in Table 2. shown. As a result of measuring the molecular weight of the polymer by GPC measurement (in terms of polystyrene), Mn was 7,900, Mw was 9,200, and Mw/Mn was 1.17.

・Second polymerization step (production 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 put in, fully degassed with nitrogen bubbling, and polymerization was started again in an 80°C thermostat. After 5 hours, the polymerization was stopped by cooling to room temperature. The amount of residual monomers was measured and measured by gas chromatography (GC), and the results of the monomer polymerization rate and block composition were calculated. The polymerization rate of each monomer was MA 85%, BA 85%, MMA>99%, and the block composition As shown in table 2. As a result of measuring the molecular weight of the block copolymer by GPC measurement (in terms of polystyrene), Mn was 46,300, Mw was 82,600, and Mw/Mn was 1.78.

・3rd polymerization step (production of polymer block (C)) Next, 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 put in, fully degassed with nitrogen bubbling, and polymerization was started again in a thermostatic bath at 70°C. After 5 hours, the polymerization was stopped by cooling to room temperature, and a solution containing a block copolymer (this was referred to as "polymer C") was obtained. The residual monomer amount was measured and measured by gas chromatography (GC), and the results of the monomer polymerization rate and block composition were calculated. The polymerization rate of each monomer was MA (the remaining part of the second polymerization step and the additional part of the third polymerization step) 83%, BA (residual part of the second polymerization step and additional part of the third polymerization step) 76%, HEA>87%, and the block composition is shown in Table 2. As a result of measuring the molecular weight of the block copolymer by GPC measurement (in terms of polystyrene), Mn was 55,400, Mw was 119,200, and Mw/Mn was 2.15.

Polymer C was obtained by reprecipitation and purification of the obtained polymerization solution from a methanol/water mixed solvent and vacuum drying. The molecular weight of the obtained polymer C was measured by GPC (in terms of polystyrene), Mn was 70,300, Mw was 132,100, and Mw/Mn was 1.88.

<Production Examples 4 and 8> Production of polymers D and H The same operations as in Production Example 3 were carried out, except that the types and amounts of the raw materials put into the flask were changed as described in Table 1, and the polymerization temperature was appropriately adjusted to obtain polymers D and H of block copolymers. The analysis results of block composition and molecular weight in polymers D and H are shown in Table 2.

[Table 1]

[Table 2]

Details of the compounds (monomers, control agents, initiators, and solvents) shown in Tables 1 and 2 are shown below. In addition, about each monomer, the Tg of the homopolymer formed from the said monomer is shown in parenthesis. The Tg of the homopolymer is quoted from the Substances and Materials Database of the National Development and Research Corporation Substances and Materials Research Institute (https://polymer.nims.go.jp/). The Tg of N-phenylmaleimide homopolymer is obtained by using the Tg (221°C) of N-phenylmaleimide/styrene alternating copolymer (62.4/37.6wt%) and styrene homopolymer The Tg (98°C) of the material is calculated by Fox's formula. MA: methyl acrylate (10°C) BA: n-butyl acrylate (-48℃) EA: Ethyl Acrylate (-21℃) MMA: methyl methacrylate (108°C) HEA: 2-hydroxyethyl acrylate (-15℃) PhMI: N-phenylmaleimide (344°C) St: Styrene (98°C) ABN-E: 2,2'-azobis(2-methylbutyronitrile) CBSTSP: 2-{[(2-carboxyethyl)thiocarbonyl]sulfanyl}propionic acid DBTTC: S,S-dibenzyl trithiocarbonate

2. Evaluation <Examples 1 to 8 and Comparative Examples 1 and 2> Each of the block copolymers (polymers A to J) produced above was used as a binder resin to prepare a slurry composition. Moreover, using the prepared slurry composition, a ceramic green sheet was produced and evaluated. The preparation method of the slurry composition, and the evaluation items of Examples and Comparative Examples are shown below.

<Preparation of slurry composition> 100 parts of barium titanate ("BT-01" manufactured by Sakai Chemical Industry Co., Ltd.), 1 part of dispersant ("malialim SC-0505K" manufactured by NOF Corporation), and 56 parts of toluene and 14 parts of ethanol as solvents, together with 100 parts of zirconia beads with a particle diameter of 0.1 mm, were stirred for 5 hours at 500 rpm using a bead mill (“Easy Nano RMB” manufactured by Imex Co., Ltd.), and the zirconia was filtered out. beads to prepare a barium titanate dispersion. To 171 parts of the dispersion liquid, 10 parts of binder resin and toluene and ethanol in the amounts described in Table 3 were added, and then stirred at 2000 rpm for 5 minutes using an autorotating revolution mixer to prepare a slurry composition.

＜Thermal decomposability of adhesive resin＞ Regarding the thermal decomposability of the binder resin, each binder resin was used as a sample, and the sample was heated to a predetermined temperature, and the mass residual ratio at the time point of reaching 500°C was evaluated. Specifically, using a thermal analyzer (TGDTA6300 manufactured by Hitachi High Tech Science Co., Ltd.), 5 to 8 mg of the sample was heated from 30°C to 600°C at a rate of 10°C/min under nitrogen flow, and the mass during this period was measured. change, and obtain the mass residual rate at the time point of reaching 500°C.

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

<The tensile properties of ceramic green sheets> The slurry composition obtained above, so that the thickness of the green sheet after drying is 100 μm, using a variable coater to coat the PET film that has been released from the mold, by performing 100 ° C × in a ventilation dryer. After drying for 15 minutes, a ceramic green sheet was produced. A 4cm×1cm test piece was cut out from the produced ceramic green sheet, and the tensile properties of the ceramic green sheet under normal conditions (25°C) were measured with a tensile testing machine at a tensile speed of 10 mm/min, and the tensile properties of the ceramic green sheet at break were obtained. Elongation (%), maximum strength (MPa) and tensile product (elongation at break (%) × maximum strength (MPa)).

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

[table 3]

As shown in Table 3, the slurry compositions of Examples 1 to 8 containing the block copolymer (P) showed a slurry viscosity as low as 1200 mPa·s or less. In addition, the obtained ceramic green sheet showed a strength as high as 1.3 MPa or more, and a sufficiently high value for the elongation at break and the tensile product. In particular, in Examples 1, 2, 5, 6, and 8, ceramic green sheets with slurry viscosity as low as 500 mPa·s or less and high strength, elongation at break, and tensile product were obtained. In addition, in Examples 2 to 5, the tensile product was as high as 150 MPa·% or more, and the toughness was excellent. Further, in Examples 1 to 3 in which the methacrylate compound was introduced into the block copolymer (P), the thermal decomposability of the binder resin was also favorable.

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 as high as 3000mPa･s or more. In addition, the strength and tensile product of the obtained ceramic green sheets were lower than those of Examples 1 to 8.

From the above results, it is clear that by using the block copolymer (P), a ceramic green sheet having high strength and excellent thermal decomposability can be produced while keeping the viscosity of the slurry composition low.

The present invention is written according to the embodiment, but it should be understood that the present invention is not limited to the embodiment. The present invention also includes various modifications or modifications within an equivalent range. In addition, various combinations or forms, even other combinations or forms of a single element including the same, its superordinate concept, or its subordinate concept are also encompassed in the scope or technical idea of the present invention.

This application is based on Japanese Patent Application No. 2020-088217 filed on May 20, 2020, the contents of which are incorporated herein by reference.

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Claims (10)

An adhesive for the manufacture of ceramic green sheets, which is an adhesive for the manufacture of ceramic green sheets containing a block copolymer, characterized by: The block copolymer 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 ceramic green sheets according to claim 1, wherein the block copolymer has 70% by mass or more of structural units derived from (meth)acrylic monomers with respect to all the structural units. The adhesive for producing ceramic green sheets according to claim 1 or 2, wherein the block copolymer has a structural unit derived from an aromatic vinyl monomer and a vinyl group derived from an imide group The structural unit of a monomer. The adhesive for producing ceramic green sheets according to any one of claims 1 to 3, wherein the block copolymer has 5% by mass to 70% by mass of methacrylic acid derived from all structural units The structural unit of an ester compound. The adhesive for producing ceramic green sheets according to any one of Claims 1 to 4, wherein the block copolymer has a polymer block with a glass transition temperature of 30°C or higher and a glass transition temperature of not less than 30°C. Polymer block at full 30°C. The binder for producing ceramic green sheets according to any one of claims 1 to 5, wherein the block copolymer has 5% by mass to 25% by mass of all structural units derived from having hydrogen bonds Structural units of vinyl monomers with functional groups. The adhesive for producing ceramic green sheets according to any one of claims 1 to 6, wherein the block copolymer has a molecular weight distribution represented by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw/Mn) is 3.0 or less. A slurry composition characterized by comprising: the binder for producing ceramic green sheets according to any one of claims 1 to 7, and ceramic powder. A ceramic green sheet is characterized by being formed by using the slurry composition described in claim 8. A method for manufacturing a multilayer ceramic capacitor, which is characterized by using the ceramic green sheet described in claim 9.