Binder composition for ceramic molding and ceramic slurry composition

Abstract

To provide a ceramic molding binder composition useful for manufacturing ceramic molded bodies with excellent strength and flexibility. [Solution] A binder composition for ceramic molding comprising the following components (A) and (B), wherein the mass ratio of the two (component (A) / component (B)) is 35 / 65 to 99.9 / 0.1. (A) (meth)acrylic polymers with an acid value of 10-160 mgKOH / g (B) Polyfunctional epoxy compounds having an epoxy equivalent of 100-500 g / eq. and 2-15 epoxy groups per molecule.

Description

[Technical Field]

[0001] The present invention relates to a binder composition for ceramic molding and a ceramic slurry composition containing the ceramic molding binder composition. [Background technology]

[0002] In the field of information and electronics, various ceramic materials such as multilayer ceramic capacitors and ceramic substrates are used as electronic components. Generally, ceramic substrates are manufactured by firing ceramic green sheets (hereinafter sometimes abbreviated as "green sheets"). Green sheets are usually obtained by preparing a ceramic slurry by mixing ceramic powder, an organic solvent, and a binder, uniformly applying it to a support using a doctor blade or similar tool, and then drying it.

[0003] In recent years, there has been a surge in the thinning of green sheets, but there is also a need for thicker films. As described in Patent Document 1, when using acrylic resin with excellent thermal decomposition properties, residual carbides after firing are reduced, but ceramic green sheets manufactured using acrylic resin as a binder lacked sufficient strength and flexibility. As a result, there was a problem in that cracks were easily formed in the green sheets during the drying process and other subsequent processes.

[0004] In this regard, Patent Document 2 describes that by using a (meth)acrylic acid-based resin having a linear alkyl group and a resin containing polyvinyl butyral, sufficient mechanical strength can be imparted and crack formation can be suppressed, and a binder for manufacturing inorganic sintered bodies and a ceramic green sheet containing the binder can be provided. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-237054 [Patent Document 2] Japanese Patent Publication No. 2019-55906 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, with the introduction of fifth-generation communication systems and the increased performance of smartphones, tablets, PCs, and other devices compatible with them, there has been a growing need to improve the voltage resistance of ceramic sheets. However, even when using the ceramic green sheet described in Patent Document 2, when attempting to increase the film thickness to improve the dielectric strength, fine cracks sometimes occurred, which reduced the dielectric strength of the ceramic sheet or impaired its physical properties such as strength and flexibility.

[0007] Therefore, the present invention aims to provide a ceramic molding binder composition useful for producing ceramic molded articles with excellent strength and flexibility. [Means for solving the problem]

[0008] The inventors of the present invention conducted diligent research to solve the aforementioned problems. As a result, they found that the aforementioned problems can be solved by using a combination of a specific (meth)acrylic polymer and a specific polyfunctional epoxy compound. The present invention relates to the following [1] and [2].

[0009] [1] A ceramic molding binder composition comprising the following components (A) and (B), wherein the mass ratio of the two (component (A) / component (B)) is 35 / 65 to 99.9 / 0.1. (A) (meth)acrylic polymers having an acid value of 10-160 mgKOH / g (B) A polyfunctional epoxy compound having an epoxy equivalent of 100-500 g / eq. and 2-15 epoxy groups per molecule. [2] A ceramic slurry composition comprising 5 to 200 parts by mass of the ceramic molding binder composition described in item [1] above and 10 to 500 parts by mass of a solvent, per 100 parts by mass of ceramic powder. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a ceramic molding binder composition useful for producing ceramic molded articles with excellent strength and flexibility. [Modes for carrying out the invention]

[0011] [Binder composition for ceramic molding] A binder composition for ceramic molding according to an embodiment of the present invention (hereinafter sometimes simply referred to as "binder composition") contains, as component (A), a (meth)acrylic polymer having an acid value of 10 to 160 mgKOH / g, and as component (B), a polyfunctional epoxy compound having an epoxy equivalent of 100 to 500 g / eq. and 2 to 15 epoxy groups per molecule. Furthermore, the mass ratio of component (A) to component (B) ((mass of component (A)) / (mass of component (B))) is in the range of 35 / 65 to 99.9 / 0.1. The following describes each component that may be included in the binder composition for ceramic molding.

[0012] (Component (A)) Component (A) may be any (meth)acrylic polymer having an acid value of 10 to 160 mgKOH / g. However, from the viewpoint of the dispersion stability of the ceramic slurry composition described later, component (A) is preferably a (meth)acrylic polymer (carboxyl-containing (meth)acrylic polymer) that contains 3 to 30 mol% of constituent units derived from monomers having carboxyl groups (hereinafter sometimes abbreviated as "carboxyl-containing constituent units") relative to its total constituent units. From the viewpoint of the polymerization stability of component (A), the amount of carboxyl-containing constituent units in component (A) is more preferably 5 to 20 mol% relative to its total constituent units. Note that "(meth)acrylic" means at least one selected from methacrylic and acrylic. The same applies to "(meth)acrylate".

[0013] (Meth)acrylic polymers containing structural units containing carboxy groups include, for example, copolymer (A) containing structural units derived from monomer (a-1) represented by the following formula (1), monomer (a-2) represented by the following formula (2), and monomer (a-3).

[0014] · Monomer (a-1) CH2=CR 2 -COOR 3 (1) (In formula (1), R 2 represents a hydrogen atom or a methyl group, and R 3 represents an alkyl group having 1 to 3 carbon atoms.).

[0015] · Monomer (a-2) CH2=CR 4 -COOR 5 (2) (In formula (2), R 4 represents a hydrogen atom or a methyl group, and R 5 represents an alkyl group having 4 to 12 carbon atoms.).

[0016] · Monomer (a-3) A monomer having a carboxy group.

[0017] Further, when the total structural units of copolymer (A) are 100 mol%, it is preferable that structural unit (a-1) derived from monomer (a-1) is 0 to 60 mol%, structural unit (a-2) derived from monomer (a-2) is 10 to 97 mol%, and structural unit (a-3) derived from monomer (a-3) is 3 to 30 mol%. More preferably, structural unit (a-1) is 0 to 50 mol%, structural unit (a-2) is 20 to 85 mol%, and structural unit (a-3) is 5 to 20 mol%. Also, the structural units are adjusted so that the acid value of this (meth)acrylic polymer is 10 to 160 mgKOH / g.

[0018] R in formula (1) 2 is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of the ease of polymerization of monomer (a-1).

[0019] R in equation (1) 3 This is an alkyl group having 1 to 3 carbon atoms, from the viewpoint of improving the degreasing properties of the ceramic slurry obtained using the binder composition of the present invention. The alkyl group may be either linear or branched.

[0020] R 3 From the viewpoint of increasing the strength of the green sheet obtained using the binder composition, and from the viewpoint of suppressing the rapid thermal decomposition of the binder composition in the temperature range of 300°C to 400°C during the degreasing treatment, it is preferably an alkyl group having 1 to 2 carbon atoms.

[0021] Examples of monomer (a-1) include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate, with methyl (meth)acrylate and ethyl (meth)acrylate being preferred. One of these may be used, or two or more may be used.

[0022] The amount of constituent unit (a-1) in copolymer (A) is preferably 0 to 60 mol%, more preferably 20 to 60 mol%, and even more preferably 30 to 50 mol%, when the total amount of constituent units is considered to be 100 mol%. By having the amount of constituent unit (a-1) within this range, a green sheet with good strength can be obtained.

[0023] R in equation (2) 4 This can be a hydrogen atom or a methyl group, but from the viewpoint of the ease of polymerization of monomer (a-2), a methyl group is preferred.

[0024] R in equation (2) 5 This is an alkyl group having 4 to 12 carbon atoms, from the viewpoint of improving the degreasing properties of the ceramic slurry composition obtained using the binder composition. The alkyl group may be linear, branched, or cyclic. That is, the alkyl group includes cycloalkyl groups.

[0025] R 5From the viewpoint of improving the flexibility of the green sheet obtained using the binder composition of the present invention, and from the viewpoint of suppressing the rapid thermal decomposition of the binder composition of the present invention in the temperature range of 300°C to 400°C during the degreasing treatment, it is preferably an alkyl group having 4 to 8 carbon atoms.

[0026] The monomer (a-2) is preferably at least one selected from the group consisting of butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. One or more of these may be used.

[0027] The amount of constituent units (a-2) in copolymer (A) is preferably 10 to 97 mol%, more preferably 30 to 90 mol%, and even more preferably 30 to 50 mol%, relative to 100 mol% of the total constituent units. By having the amount of constituent units (a-2) within this range, a high-strength green sheet can be obtained.

[0028] Monomer (a-3) can be any monomer having a carboxyl group, and is not particularly limited. Specific examples of monomers having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, ω-carboxy-polycaprolactone mono(meth)acrylate [e.g., ω-carboxy-polycaprolactone (n≒2) monoacrylate], succinic acid esters (e.g., 2-acryloyloxyethyl succinic acid), etc. Among these, acrylic acid is preferred as the monomer having a carboxyl group from the viewpoint of copolymerizability. One of these may be used, or two or more may be used.

[0029] The amount of constituent unit (a-3) in copolymer (A) is preferably 3 to 30 mol%, and more preferably 5 to 20 mol%, relative to the total number of constituent units. By having the amount of constituent unit (a-3) within this range, the uniformity of the resulting ceramic slurry composition is enhanced, and high-strength ceramic molded articles can be produced.

[0030] In addition to the monomers (a-1) to (a-3) mentioned above, other monomers copolymerizable with these can be used as monomers constituting copolymer (A). Examples of such monomers (a-4) include (meth)acrylic acid esters and vinyl compounds other than monomers (a-1) to (a-3). Monomer (a-4) may be used alone or in combination of two or more.

[0031] Examples of (meth)acrylic acid esters other than monomers (a-1) to (a-3) include phenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, hydroxyphenyl (meth)acrylate, glycidyl (meth)acrylate, and ethylene oxide adducts of (meth)acrylic acid.

[0032] Examples of vinyl compounds include styrene monomers such as styrene, vinyltoluene, and α-methylstyrene; maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, phenylmaleimide, and cyclohexylmaleimide; nitrile group-containing vinyl monomers such as (meth)acrylonitrile; amide group-containing vinyl monomers such as (meth)acrylamide; and vinyl esters such as vinyl acetate and vinyl benzoate.

[0033] The copolymer (A) described above can be obtained, for example, as follows.

[0034] First, a mixture is prepared by mixing a surfactant (also called an emulsifier), a solvent, and a monomer. The mixture may be obtained, for example, by pre-mixing the monomer with the surfactant and solvent, or by mixing polyethylene oxide, the surfactant, and the solvent, and then adding and mixing the monomer.

[0035] Examples of surfactants include anionic surfactants, nonionic surfactants, and amphoteric surfactants. For example, anionic surfactants such as sulfate esters of higher alcohols, alkylbenzene sulfonates, fatty acid sulfonates, phosphates (e.g., ammonium monoglyceride phosphate), fatty acid salts (e.g., dipotassium alkenylsuccinate), and amino acid derivative salts are preferred. Nonionic surfactants such as alkyl esters, alkyl ethers, and alkylphenyl ethers of ordinary polyethylene glycol are preferred. Amphoteric surfactants having carboxylates, sulfate esters, sulfonates, or phosphate esters in the anionic part and amine salts, quaternary ammonium salts, etc. in the cationic part are preferred. These may be used individually or in combination of two or more.

[0036] The amount of surfactant added for emulsion polymerization is typically 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass, per 100 parts by mass of the total amount of monomers used. When the amount of emulsifier added is within this range, it is easy to control the volume-average particle size of the polymer to 50 to 300 nm.

[0037] The solvent is preferably water, but it may also be a mixed solvent containing water and a hydrophilic organic solvent. A hydrophilic organic solvent is an organic solvent that is readily miscible with water or readily soluble in water.

[0038] The hydrophilic organic solvent may contain at least one component selected from the group consisting of methanol, ethanol, propyl alcohol, isopropyl alcohol, propylene glycol monomethyl ether, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, polyethylene glycol monomethyl ether, and methyl 2-hydroxyisobutyrate.

[0039] The hydrophilic organic solvent is preferably at least one of propylene glycol monomethyl ether, isopropyl alcohol, and ethylene glycol monotertiary butyl ether.

[0040] The solvent content in the mixture is preferably in the range of 30 to 99% by mass, and more preferably in the range of 40 to 99% by mass, relative to the total volume of the mixture, in order to maintain uniform dispersion of the mixture. When a mixed solvent containing water and a hydrophilic organic solvent is used as the solvent, the amount of the hydrophilic organic solvent is preferably in the range of 5 to 20% by mass relative to the total volume of the solvent, in order to obtain a stable mixture.

[0041] A polymerization initiator may be added to the mixture. The polymerization initiator may contain, for example, at least one of a water-soluble polymerization initiator and an oil-soluble polymerization initiator.

[0042] The water-soluble polymerization initiator contains, for example, at least one compound selected from the group consisting of ammonium persulfate, 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate, 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and 4,4-azobis(4-cyanovaleric acid).

[0043] The oil-soluble polymerization initiator contains, for example, at least one compound selected from the group consisting of 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-(2,4-dimethyl-4-methoxyvaleronitrile), 4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, benzoyl peroxide, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, and t-butyl peroxide.

[0044] The mixture may contain a chain transfer agent. In this case, the chain transfer effect appropriately adjusts the crosslinking density of the monomers, thereby suppressing an excess of crosslinking sites in the polymerization reaction product and controlling the molecular weight.

[0045] The chain transfer agent contains at least one compound selected from the group consisting of, for example, n-dodecyl mercaptan, 2,4-diphenyl-4-methyl-1-pentene, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol.

[0046] Copolymer (A) can be synthesized by emulsion polymerization of monomers in the mixture. It is preferable to reduce the dissolved oxygen in the mixture before emulsion polymerization. To do this, it is preferable to bubble the mixture with an inert gas such as nitrogen gas. Alternatively, the mixture may be prepared by bubbling the mixture with an inert gas before adding the monomers.

[0047] Emulsion polymerization can be carried out by heating the mixture. Alternatively, the mixture may be heated before the monomer is added to allow the emulsion polymerization to proceed. It is also preferable to thoroughly mix the monomer with the surfactant and water in the mixture before the monomer emulsion polymerization reaction. In this case, the storage stability of the ceramic molding binder composition according to this embodiment tends to improve. The heating temperature is, for example, in the range of 40 to 100°C, and the heating time is, for example, in the range of 2 to 10 hours. The reaction conditions are set appropriately within a range that does not inhibit the action of copolymer (A). This yields a mixture containing copolymer (A), surfactant, and solvent. The obtained mixture can be used as is, or, if necessary, the concentration of copolymer (A) can be adjusted with the solvent, and then used to prepare the binder composition.

[0048] The volume-average particle diameter of the copolymer (A) in the mixture (the volume-average particle diameter of the dispersed polymer (A) particles in the mixture) is preferably 50 to 500 nm, more preferably 100 to 300 nm. The volume-average particle diameter can be measured and calculated, for example, using a Beckman Coulter LS 13 320.

[0049] (Component (B)) The epoxy equivalent of component (B) is 100 to 500 g / eq., and there are no particular limitations as long as it is a polyfunctional epoxy compound having 2 to 15 epoxy groups per molecule, but preferably it is a polyfunctional epoxy compound having 250 to 500 g / eq., and an epoxy compound having at least two epoxy groups in the molecule can be used. Within the above epoxy equivalent range, the flexibility of sheet-like ceramic molded articles such as green sheets is improved. Furthermore, epoxy compounds having 2 to 15 epoxy groups per molecule may be used alone or in combination of two or more types. When using two or more types in combination, it is preferable to use an epoxy compound (B-1) having 2 to 3 epoxy groups per molecule (hereinafter sometimes referred to as component (B-1)) and an epoxy compound (B-2) having 4 to 15 epoxy groups per molecule (hereinafter sometimes referred to as component (B-2)). The epoxy equivalent can be determined in accordance with JIS K7236:2009.

[0050] The number of epoxy groups per molecule of component (B-1) is not particularly limited, as long as it is between 2 and 3. If the number of epoxy groups in a molecule of component (B-1) is less than 2, the sheet may lack flexibility.

[0051] Specific examples of component (B-1) include polyethylene glycol diglycidyl ether, polyethylene glycol monoglycidyl ether, polypropylene glycol diglycidyl ether, phenol (EO) 5 glycidyl ether, lauryl alcohol (EO) 15 glycidyl ether, trimethylolpropane polyglycidyl ethers, etc. Commercially available products can be used as component (B-1), for example, Denacol EX-313, 821, 830, 841, 850, 920, etc., manufactured by Nagase ChemteX Corporation.

[0052] The number of epoxy groups in one molecule of component (B-2) is not particularly limited as long as it is between 4 and 15, but is preferably between 4 and 10, and more preferably between 4 and 8. If the number of epoxy groups in one molecule of component (B-2) exceeds 15, the storage stability may decrease.

[0053] Specific examples of component (B-2) include sorbitol polyglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, and cresol novolac polyglycidyl ether. As component (B-1), commercially available products can be used, for example, Denacol EX-512 and EX-521 manufactured by Nagase ChemteX Corporation.

[0054] Component (B) can be one or more selected from components (B-1) and (B-2), but it is preferable to use a combination of components (B-1) and (B-2). When combining the two, one type of component (B-1) and one type of component (B-2) may be used, or two or more types of each may be used.

[0055] When using components (B-1) and (B-2) in combination, the mass ratio (B-1 / B-2) of components (B-1) and (B-2) is not particularly limited, but is preferably 0.1 / 99.9 to 99.9 / 0.1. Within this mass ratio range, the strength and flexibility of the ceramic molded body (especially the green sheet) formed using the ceramic slurry composition containing the binder composition are improved. The mass ratio is more preferably 10 / 90 to 90 / 10, and even more preferably 20 / 80 to 80 / 20.

[0056] From the viewpoint of the strength and flexibility of the ceramic molded article, such as the green sheet, the content of components (A) and (B) in the binder composition is preferably such that the mass ratio of component (A) to component (B) (mass of component (A) / mass of component (B)) is 35 / 65 to 99.9 / 0.1. When the mass ratio of component (A) to component (B) is within the above range, the strength and flexibility of the ceramic molded article, especially the green sheet, are improved. From the viewpoint of the strength and flexibility of the ceramic molded article, especially the green sheet, the mass ratio of component (A) to component (B) (mass of component (A) / mass of component (B)) is preferably 67 / 33 to 95 / 5, and more preferably 67 / 33 to 83 / 17.

[0057] The binder composition can be obtained by mixing and stirring the aforementioned components (A) and (B). As described above, if component (A) is copolymer (A), a mixture containing a surfactant and a solvent may be used. Therefore, the binder composition may contain the aforementioned copolymer A) and component (B), as well as a surfactant and a solvent.

[0058] [Ceramic slurry composition] The ceramic slurry composition according to the embodiment of the present invention contains 5 to 200 parts by mass of the aforementioned binder composition and 10 to 500 parts by mass of solvent per 100 parts by mass of ceramic powder. However, the solvent content shall be such that the total amount including the solvent in the binder composition, if the binder composition contains solvent, is within the aforementioned range.

[0059] The ceramic powder may be either an oxide-based ceramic powder or a non-oxide-based ceramic powder, and one of these may be used alone or two or more may be used in combination. Examples of oxide-based ceramic powders include alumina, titania, zirconia, barium titanate, and lead zirconate titanate. Examples of non-oxide-based ceramic powders include silicon carbide and silicon nitride. The ceramic powder is preferably a non-oxide-based ceramic powder, and more preferably silicon nitride.

[0060] The particle size of the ceramic powder can be appropriately determined depending on the application, but the volume-based median diameter d50 of the ceramic powder, as measured by a laser diffraction scattering particle size distribution analyzer, is preferably 0.05 to 50.0 μm, more preferably 0.10 to 10.0 μm, even more preferably 0.20 to 5.00 μm, and particularly preferably 0.20 to 1.50 μm, from the viewpoint of dispersibility in the ceramic slurry composition.

[0061] The solvent can be, for example, water, a hydrophilic organic solvent, or the same solvent used in the synthesis of copolymer (A) described above. From the viewpoint of the stability of the ceramic slurry composition, the solvent content in the ceramic slurry composition is preferably 10 to 500 parts by mass, more preferably 20 to 200 parts by mass, and even more preferably 25 to 100 parts by mass, per 100 parts by mass of ceramic powder. If the binder composition contains a solvent, the total amount including the solvent should be used.

[0062] The ceramic slurry composition according to the embodiment may contain a dispersant. The applicable dispersant is not particularly limited, and any cationic dispersant, anionic dispersant, nonionic dispersant, or amphoteric dispersant can be used. Polymeric dispersants may also be used. Furthermore, one of these dispersants may be used alone, or two or more may be used in combination.

[0063] Examples of cationic dispersants include polyamine-based dispersants. Examples of anionic dispersants include carboxylic acid-based dispersants, phosphate ester-based dispersants, sulfate ester-based dispersants, and sulfonic acid ester-based dispersants. Examples of nonionic dispersants include polyethylene glycol-based dispersants. Examples of polymer-based dispersants include polymer polycarboxylic acid-based dispersants. The dispersant is preferably a polymer-based dispersant, and more preferably a polymer polycarboxylic acid-based dispersant.

[0064] From the viewpoint of the stability of the ceramic slurry composition, the content of the dispersant in the ceramic slurry composition is preferably 0 to 8.0 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.5 to 4.5 parts by mass, per 100 parts by mass of ceramic powder.

[0065] The ceramic slurry composition according to the embodiment may contain a plasticizer. There are no particular limitations on the applicable plasticizers, and examples include alkyl polyether-based plasticizers and phthalate ester-based plasticizers. One of these plasticizers may be used alone, or two or more may be used in combination.

[0066] The content of the plasticizer in the ceramic slurry composition is preferably 0 to 80 parts by mass, more preferably 10 to 60 parts by mass, and even more preferably 20 to 50 parts by mass, per 100 parts by mass of ceramic powder, from the viewpoint of peeling the sheet-like ceramic molded body, especially the green sheet, from the substrate.

[0067] The content of the aforementioned binder composition in the ceramic slurry composition is 5 to 200 parts by mass, preferably 20 to 150 parts by mass, per 100 parts by mass of ceramic powder. From the viewpoint of the stability of the ceramic slurry composition, it is preferable to adjust the content of the aforementioned binder composition considering the content of components (A) and (B) in the ceramic slurry composition. The total amount of components (A) and (B) in the ceramic slurry composition is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 20 to 45 parts by mass, per 100 parts by mass of ceramic powder. When a mixture after reaction, such as the copolymer (A) described above, is used as component (A), the content of component (A) can be determined based on the value obtained from the solid content concentration of the mixture.

[0068] The ceramic slurry composition according to the embodiment of the present invention may contain other components different from the binder composition, ceramic powder, solvent, dispersant, and plasticizer described above, as long as they do not impede the effects of the present invention. Examples of other components include defoaming agents. Only one of the other components may be used, or two or more may be used in combination.

[0069] [Ceramic molded bodies and their manufacturing methods] A ceramic molded body (e.g., a green sheet) can be manufactured using the aforementioned ceramic slurry composition. There are no particular limitations on the manufacturing method. Known methods include, for example, press molding and sheet molding. When forming a sheet-like molded body such as a green sheet as the ceramic molded body, the sheet molding method can be used. In the sheet molding method, the aforementioned ceramic slurry composition can be applied to a support to a desired thickness using a film applicator or the like, and then dried to obtain a sheet-like ceramic molded body.

[0070] There are no particular limitations on the support material used in the sheet molding method, and any known material can be used. Examples of support materials include polyethylene terephthalate, polycarbonate, stainless steel (SUS), and glass plates.

[0071] There are no particular limitations on the drying method for the ceramic slurry composition applied to the support, and drying can be carried out by known methods. Examples of drying equipment include drying ovens and hot dryers. The drying atmosphere may be an atmospheric atmosphere or an inert gas atmosphere such as nitrogen gas. The drying pressure may be at normal pressure or under reduced pressure. The drying temperature and time can be appropriately selected depending on the components of the ceramic slurry composition. For example, drying can be carried out by gradually increasing the drying temperature. More specifically, the ceramic slurry composition applied to the support may be dried at room temperature for 30 minutes to 2 hours, then dried at 30 to 50°C for 30 minutes to 2 hours, and then dried at 80 to 120°C for 1 to 3 hours. Furthermore, it is preferable to apply the ceramic slurry composition to the support such that the thickness of the green sheet obtained after drying is 0.5 to 300 μm.

[0072] A sheet-like ceramic molded body, such as a green sheet, can be obtained by degreasing the dried sheet-like ceramic molded body to remove organic components. There are no particular limitations on the degreasing method, and known methods can be used. For example, organic components can be removed by heat treatment using an electric furnace or the like, under an inert gas atmosphere, for example, at 350-500°C for 30-150 minutes.

[0073] The ceramic molded body obtained as described above, being formed using a slurry composition containing the aforementioned binder composition, possesses excellent strength and flexibility. These properties can be evaluated by the methods described in the Examples section below. [Examples]

[0074] The embodiments of the present invention will be described in detail below based on examples and comparative examples.

[0075] [Synthesis of component (A)] (Synthesis Example 1: Synthesis of Component (A-1)) As monomer (a-2), 249.5g of butyl acrylate, 33.4g of butyl methacrylate, and 8.7g of 2-ethylhexyl acrylate were mixed for 5 minutes to prepare an emulsion, and as monomer (a-3), 8.5g of acrylic acid, 7.8g of Sanyo Chemical Industries' "Eleminol JS-20" as an emulsifier, and 125.1g of ion-exchanged water were added to the dropping tank. In a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet, 125.1 g of deionized water, 0.3 g of sodium bicarbonate, and 0.6 g of ammonium persulfate were added. Next, 21.6 g of emulsion was added dropwise from the dropping tank to the reaction vessel. After raising the internal temperature to 80°C, the reaction was maintained at 80°C for 20 minutes, and then the remaining emulsion was added dropwise from the dropping tank to the reaction vessel over 180 minutes. After the emulsion was added dropwise, the temperature inside the reaction vessel was maintained at 80°C for 120 minutes, and then cooled to room temperature to obtain a solution of component (A-1), which is a copolymer. The solid content concentration of the obtained solution was measured by the method described later and was found to be 50% by mass. This solution of component (A-1) (50% solution) was used to prepare the binder composition. Note that the solid content concentration corresponds to the concentration of component (A-1) in the solution.

[0076] (Synthesis Example 2: Synthesis of Component (A-2)) A 50% solution of the copolymer component (A-2) was obtained by the same method as in Synthesis Example 1, except that monomer (a-1) was changed to methyl methacrylate (124.5 g), monomer (a-2) to butyl acrylate (156.2 g) and 2-ethylhexyl acrylate (9.8 g), and monomer (a-3) to acrylic acid (9.6 g).

[0077] (Synthesis Example 3: Synthesis of Component (A-3)) A 50% solution of the copolymer component (A-3) was obtained by the same method as in Synthesis Example 1, except that monomer (a-1) was changed to methyl methacrylate (112.4 g), monomer (a-2) to butyl acrylate (136.8 g) and 2-ethylhexyl acrylate (10.4 g), and monomer (a-3) to acrylic acid (40.5 g).

[0078] (Synthesis Example 4: Synthesis of component (A'-1)) A 50% solution of the copolymer component (A'-1) was obtained by the same method as in Synthesis Example 1, except that monomer (a-1) was changed to methyl methacrylate 97.0 g, monomer (a-2) to butyl acrylate 124.3 g and 2-ethylhexyl acrylate 10.8 g, and monomer (a-3) to acrylic acid 67.8 g.

[0079] (Synthesis Example 5: Synthesis of component (A'-2)) A 50% solution of the copolymer component (A'-2) was obtained by the same method as in Synthesis Example 1, except that monomer (a-1) was changed to methyl methacrylate 130.8 g, monomer (a-2) to butyl acrylate 157.6 g and 2-ethylhexyl acrylate 9.6 g, and monomer (a-3) to acrylic acid 1.9 g.

[0080] (Measurement of solid content concentration) Approximately 1.0 g of each polymer solution sample obtained in Synthesis Examples 1-5 was added to an aluminum container (φ=50 mm, height=20 mm), accurately weighed, and dried in a vacuum dryer at 120°C under reduced pressure of 10 hPa or less for 30 minutes to remove volatile components. The mass was then measured. The mass of the sample after removal of volatile components was taken as the solid content, and the solid content concentration (%) was obtained by dividing it by the mass of the added sample.

[0081] (Measurement of acid value) The acid value of each copolymer obtained in Synthesis Examples 1 to 5 was determined in accordance with JIS K 0070-1992.

[0082] Table 1 shows the types, mole fractions, and acid values ​​of monomers used in Synthesis Examples 1-5. The meanings of the abbreviations in Table 1 are as follows. MMA: Methyl methacrylate BA: Butyl acrylate BMA: Butyl methacrylate 2-EHA: 2-ethylhexyl acrylate AA: Acrylic acid

[0083] [Table 1]

[0084] [Examples 1-11 and Comparative Examples 1-4] <Manufacturing of Binder Composition> A binder composition was prepared by mixing and stirring 50% solutions of each copolymer obtained in Synthesis Examples 1-5 with a polyfunctional epoxy compound, which is component (B), in the proportions shown in Tables 2 and 3. Component B in Tables 2 and 3 is as follows. Also, in Tables 2 and 3, the numbers in parentheses for component (A) indicate the solid content (polymer) value.

[0085] (B-1) EX-313 Denacol EX-313, manufactured by Nagase ChemteX Corporation, glycerol polyglycidyl ether, epoxy equivalent: 141 g / eq, number of epoxy groups per molecule: 2-3. EX-821 Denacol EX-821, manufactured by Nagase ChemteX Corporation, polyethylene glycol diglycidyl ether, epoxy equivalent: 185 g / eq, number of epoxy groups per molecule: 2. EX-830 Denacol EX-830, manufactured by Nagase ChemteX Corporation, polyethylene glycol diglycidyl ether, epoxy equivalent: 268 g / eq, number of epoxy groups per molecule: 2. EX-841 Denacol EX-841, manufactured by Nagase ChemteX Corporation, polyethylene glycol diglycidyl ether, epoxy equivalent: 372 g / eq, number of epoxy groups per molecule: 2. EX-850 Denacol EX-850, manufactured by Nagase ChemteX Corporation, polyethylene glycol diglycidyl ether, epoxy equivalent: 122 g / eq, number of epoxy groups per molecule: 2. EX-920 Denacol EX-920, manufactured by Nagase ChemteX Corporation, polypropylene glycol diglycidyl ether, epoxy equivalent: 176 g / eq, number of epoxy groups per molecule: 2.

[0086] (B-2) EX-512 Denacol EX-512, manufactured by Nagase ChemteX Corporation, is a polyglycerol polyglycidyl ether with an epoxy equivalent of 168 g / eq and containing 4 epoxy groups per molecule. EX-521 Denacol EX-521, manufactured by Nagase ChemteX Corporation, is a polyglycerol polyglycidyl ether with an epoxy equivalent of 183 g / eq and containing 5 epoxy groups per molecule.

[0087] <Manufacturing of ceramic slurry compositions> A ceramic slurry composition was prepared by placing 15 parts by mass of silicon nitride (manufactured by Denka Co., Ltd.: "SN-9S", median diameter d50 by volume: 1.1 μm) as ceramic powder, 10 parts by mass of deionized water, 0.6 parts by mass of a polymer polycarboxylic acid dispersant (manufactured by NOF Corporation: "Marialim AKM-0531"), and 15 parts by mass of zirconia balls with a particle size of 1 mm into a ball mill, mixing and stirring for 8 hours, then adding 9 parts by mass of a binder composition, mixing and stirring for a further 48 hours, and finally filtering off the zirconia balls.

[0088] <Manufacturing of ceramic molded products (green sheets)> The obtained ceramic slurry composition was applied in a sheet-like manner onto a PET film using a film applicator, then dried at room temperature for 1 hour, followed by drying at 40°C for 1 hour, and then at 100°C for 2 hours to produce a green sheet (thickness: 0.5 mm).

[0089] [Sheet Strength Test] From the obtained green sheet, strip-shaped test pieces measuring 0.5 mm in thickness, 60 mm in length, and 20 mm in width were cut out. Tensile tests were performed at a speed of 10 mm / min using an Autograph (Shimadzu Corporation: EZ-SX) to measure the tensile strength, and the sheet strength was evaluated according to the following criteria. ◎: Tensile strength of 4.50 N / mm 2 That's all. ○: Tensile strength of 2.00 N / mm 2 More than 4.50N / mm 2 less than △: Tensile strength of 2.00 N / mm 2 less than

[0090] [Sheet stretchability test] In the same manner as the sheet strength test described above, test specimens were prepared and tensile tests were performed to measure the elongation at break (%) (=100 × (L - L0) / L0, L0: gauge length, L: gauge length at break), and the sheet elongation was evaluated according to the following criteria. ◎: Elongation at break is 40.0% or more ○: Elongation at break is 15.0% or more and less than 40.0% △: Elongation at break is less than 15.0%

[0091] [Crack Test] A green sheet with a thickness of 0.1 mm, a width of 1 cm, and a length of 9 cm was wrapped around a glass rod with a diameter of 20 mm. The number of cracks larger than 3 mm on the green sheet was visually measured, and the flexibility of the film was evaluated according to the following criteria. ◎: Number of cracks is 0 ○: Number of cracks: 1-3 △: Number of cracks is 4 or more

[0092] The evaluation results are shown in Tables 2 and 3.

[0093] [Table 2]

[0094] [Table 3]

[0095] As shown in Tables 2 and 3, the green sheet, a ceramic molded body formed using a ceramic slurry composition containing a binder composition with predetermined components (A) and (B), exhibits good strength and flexibility. In particular, combining components (B-1) and (B-2) as component (B) results in superior strength and flexibility compared to the case where either component is included. On the other hand, Comparative Example 1, which did not contain component (B), and Comparative Example 2, in which the mass ratio of component (A) to component (B) was outside the specified range, showed low sheet strength. Comparative Examples 3 and 4, which used components (A'-1) and (A'-2), which are not the specified component (A), showed inferior strength and flexibility compared to the examples.

Claims

1. A binder composition for ceramic molding, comprising the following components (A) and (B), wherein the mass ratio of the two (component (A) / component (B)) is 35 / 65 to 99.9 / 0.

1. (A) (meth)acrylic polymer having an acid value of 10 to 160 mg KOH / g (B) Polyfunctional epoxy compounds having an epoxy equivalent of 100 to 500 g / eq. and 2 to 15 epoxy groups per molecule.

2. A ceramic slurry composition comprising 100 parts by mass of ceramic powder, 5 to 200 parts by mass of the ceramic molding binder composition described in claim 1, and 10 to 500 parts by mass of solvent.

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