Binder composition for molding ceramic, and ceramic slurry

Abstract

To provide a binder composition for molding a ceramic useful for manufacturing a ceramic molding excellent in strength, elongation, and flexibility.SOLUTION: A binder composition for molding a ceramic includes a component (A): a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a Mw of 400,000 to 1,000,000, a component (B): a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a Mw of 30,000 to 300,000, and a component (C): a copolymer expressed by R1O-(EO)p-(PO)q-H, wherein, based on 100 pts.mass of the total of (a) to (C), an amount of the component (A) is 10 to 70 pts.mass, an amount of the component (B) is 10 to 40 pts.mass, and an amount of the component (C) is 1 to 50 pts.mass, and a mass ratio of the amount of the component (A) / the amount of the component (B) is within a range of 40 / 60 to 85 / 15.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the information and electronics field, various ceramic materials are used as electronic components, such as multilayer ceramic capacitors and ceramic substrates. Ceramic substrates are generally 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, applying it uniformly onto a support using a doctor blade or the like, and then drying it.

[0003] Examples of binders used in green sheets include butyral resins and acrylic resins. Polyvinyl butyral has excellent strength and elongation and is widely used. However, as described in Patent Document 1, polyvinyl butyral has poor degreasing properties when decomposed and removed by heat treatment (hereinafter sometimes referred to as "degreasing"). Therefore, when polyvinyl butyral is used, residues are generated on the green sheet, which can affect the electrical properties of the ceramic substrate.

[0004] On the other hand, acrylic resins have excellent degreasing properties but lack sufficient dispersibility. In this regard, Patent Document 2 describes that by using a copolymer obtained by copolymerizing a monomer mainly composed of a (meth)acrylic acid ester and a (meth)acrylic acid ester having a polyoxyethylene chain as a binder for ceramic molding, it is possible to provide a binder with improved affinity with powder and improved dispersion stability.

[0005] Patent Document 3 shows that a green sheet with excellent strength can be obtained by using a binder composition containing a high molecular weight acrylic copolymer A having a carboxy group and a low molecular weight acrylic copolymer B having a hydroxyl group. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-202987 [Patent Document 2] Japanese Patent Application Publication No. 6-72759 [Patent Document 3] Japanese Patent Application Publication No. 2020-132490 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, with the spread of electric vehicles, ceramic sheets are being used at higher voltages and temperatures than ever before, and therefore ceramic sheets are being required to have better voltage resistance and heat dissipation. To achieve better voltage resistance and heat dissipation, thicker ceramic sheets are being required. To produce thicker ceramic sheets, binders that can produce green sheets with excellent strength and flexibility are being required.

[0008] However, when conventional binders are used, problems such as cracks occurring in the green sheet during molding into a thick green sheet occur. Furthermore, the strength and flexibility of the green sheet obtained using conventional binders are not satisfactory. Furthermore, ceramic slurries obtained using conventional binders are sometimes left for several hours to several days after production due to process factors such as the degassing process, and this can result in the formation of fine precipitates. Using ceramic slurries with precipitates can lead to defects in the resulting green sheets.

[0009] An object of the present invention is to provide a ceramic molding binder composition that is useful for producing ceramic molded bodies (particularly thick green sheets) that are excellent in strength, extensibility, and flexibility. [Means for solving the problem]

[0010] The present invention that can achieve the above object is as follows. [1] The following components (A) to (C): (A) a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 400,000 to 1,000,000; (B) a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 30,000 to 300,000, and (C) Formula (1): R 1 O-(EO) p -(PO) q -H (1) (In the formula, R 1 represents an alkyl group having 5 to 9 carbon atoms, EO represents an oxyethylene group; PO represents an oxypropylene group; p is a number between 3 and 9, q is a number between 2 and 4, and p / q is in the range of 1.0 to 3.0.) A copolymer represented by A ceramic molding binder composition comprising: The amount of component (A) is 10 to 70 parts by mass, the amount of component (B) is 10 to 40 parts by mass, and the amount of component (C) is 1 to 50 parts by mass, relative to 100 parts by mass in total of components (A) to (C); and A ceramic molding binder composition, wherein the mass ratio of the amount of component (A) to the amount of component (B) is within the range of 40 / 60 to 85 / 15. [2] The ceramic molding binder composition according to [1], wherein component (A) is a (meth)acrylic polymer containing structural units derived from a monomer having a hydroxyl group in an amount of 3 to 30 mol % based on the total structural units. [3] The ceramic molding binder composition according to [1], wherein component (B) is a (meth)acrylic polymer containing structural units derived from a monomer having a hydroxyl group in an amount of 3 to 30 mol % based on the total structural units. [4] A ceramic slurry comprising the ceramic molding binder composition according to any one of [1] to [3] above, ceramic powder, a dispersant, and an organic solvent. [5] The ceramic slurry according to [4], wherein the total amount of components (A) to (C) is 5 to 100 parts by mass, the amount of dispersant is 0.1 to 10 parts by mass, and the amount of organic solvent is 10 to 500 parts by mass, relative to 100 parts by mass of ceramic powder. [Effects of the Invention]

[0011] According to the present invention, a ceramic molding binder composition useful for producing ceramic molded bodies (particularly thick green sheets) having excellent strength, extensibility, and flexibility can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0012] In this specification, numerical ranges defined using "to" are inclusive of the numerical values at both ends (upper and lower limits) of "to." For example, "2 to 4" means 2 or more and 4 or less. In this specification, "(meth)acrylate" refers to acrylate or methacrylate. Here, only one type of (meth)acrylate may be used, or two or more types may be used in combination. Therefore, when two or more types of (meth)acrylates can be present, "(meth)acrylate" refers to acrylate and / or methacrylate. Other terms similar to "(meth)acrylate" also have the same meaning as "(meth)acrylate."

[0013] <Binder composition for ceramic molding> The ceramic molding binder composition of the present invention (hereinafter sometimes referred to as "the binder composition of the present invention") contains components (A) to (C). Components (A) to (C) will be explained in order below.

[0014] <Component (A)> The component (A) used in the present invention is a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 400,000 to 1,000,000.

[0015] In this specification, the term "(meth)acrylic polymer" refers to a polymer having structural units derived from (meth)acrylic acid or its ester. As used herein, the term "structural unit" refers to a repeating structure in a polymer derived from a monomer. Therefore, a structure in a polymer derived from a polymerization initiator or a chain transfer agent is not considered a "structural unit" in this specification.

[0016] The hydroxyl value of component (A) must be 5 to 50 mgKOH / g. If the hydroxyl value of component (A) is less than 5 mgKOH / g, the sheet strength will be insufficient when formed into a green sheet. If the hydroxyl value of component (A) exceeds 50 mgKOH / g, aggregation will occur during polymerization of component (A), making the polymerization difficult. From the viewpoints of green sheet strength and stability during polymerization of component (A), the hydroxyl value of component (A) is preferably 5 to 40 mgKOH / g, more preferably 10 to 30 mgKOH / g.

[0017] The weight-average molecular weight of component (A) must be 400,000 to 1,000,000. If the weight-average molecular weight of component (A) is less than 400,000, the strength of the green sheet obtained using the binder composition of the present invention will be insufficient. Furthermore, if the weight-average molecular weight of component (A) exceeds 1,000,000, the ceramic slurry obtained using the binder composition of the present invention will be prone to stringiness, impairing the surface smoothness of the ceramic molded body (particularly the green sheet). From the viewpoints of green sheet strength and ceramic slurry handleability, the weight-average molecular weight of component (A) is preferably 400,000 to 900,000, more preferably 500,000 to 800,000. The weight-average molecular weight of component (A) can be determined in terms of polystyrene using gel permeation chromatography (GPC).

[0018] The glass transition temperature of component (A) is preferably 30 to 80°C. If the glass transition temperature of component (A) is less than 30°C, the surface of the green sheet becomes sticky and difficult to handle. If the glass transition temperature of component (A) exceeds 80°C, segregation of the ceramic slurry may occur, resulting in a deterioration in the stability of the ceramic slurry. From the viewpoint of the handleability of the green sheet and the stability of the ceramic slurry, the glass transition temperature of component (A) is more preferably 30 to 75°C, and even more preferably 40 to 60°C.

[0019] The glass transition temperature (Tg) of the copolymer can be calculated, for example, from the mass fraction of each monomer in the copolymer and the glass transition temperature of a homopolymer of each monomer, using the following formula (I): 1 / Tg =m1 / Tg1+m2 / Tg2+···+m n / Tg n (I) (In the above formula, Tg is the glass transition temperature (K) of the copolymer, and m1, m2, and m n are the mass fractions of each monomer in the copolymer, and m1, m2, and m n The sum of Tg1, Tg2, and Tg nis the glass transition temperature (K) of the homopolymer of each monomer. It can be found by:

[0020] The glass transition temperatures (Tg1, Tg2, and Tg n The glass transition temperature (Tg) of the copolymer can be calculated from the inflection point of the DSC curve obtained by measuring 10 mg of a measurement sample at a temperature rise rate of 10°C / min in a nitrogen gas flow using a differential scanning calorimetry (DSC) device (e.g., Seiko Instruments Inc., Model No. EXSTAR6000). The glass transition temperature (Tg) of the copolymer can also be calculated in the same manner.

[0021] From the viewpoint of dispersion stability of the ceramic slurry, component (A) is preferably a (meth)acrylic polymer containing structural units derived from monomers having hydroxyl groups (hereinafter sometimes abbreviated as "structural units containing hydroxyl groups") in an amount of 3 to 30 mol % based on all structural units. From the viewpoint of stability during polymerization of component (A), the amount of structural units containing hydroxyl groups in component (A) is more preferably 5 to 15 mol % based on all structural units.

[0022] Component (A) is a compound represented by formula (2): CH2=CR 2 -COO-R 3 (2) (In the formula, R 2 represents a hydrogen atom or a methyl group, and R 3 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. a structural unit derived from a monomer (a-1) represented by the formula (3): CH2=CR 4 -COO-R 5 (3) (In the formula, R 4 represents a hydrogen atom or a methyl group, and R 5 represents a hydroxyalkyl group having 1 to 8 carbon atoms and having 1 or 2 hydroxyl groups. A structural unit derived from a monomer (a-2) represented by the formula (hereinafter, sometimes abbreviated as "structural unit (a-2)") In this copolymer (hereinafter sometimes referred to as "copolymer (A)"), the amount of structural units (a-1) is 70 to 97 mol % and the amount of structural units (a-2) is 3 to 30 mol % based on all structural units. The hydroxyl value, weight average molecular weight, and glass transition temperature of copolymer (A) are the same as those described above for component (A).

[0023] In the present invention, a distinction is made between a carboxy group and a hydroxyl group, and therefore the OH in a carboxy group (—CO—OH) is not included in the “hydroxyl group” in this specification.

[0024] To produce the copolymer (A), the monomer (a-1) and the monomer (a-2) may be used either alone or in combination of two or more.

[0025] R in equation (2) 2 is hydrogen or a methyl group, and is preferably a methyl group from the viewpoint of ease of polymerization of the monomer (a-1).

[0026] R in equation (2) 3 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, from the viewpoint of improving the degreasing property of the ceramic slurry obtained using the binder composition of the present invention. In this specification, the "alkyl group" may be linear, branched, or cyclic. In other words, in this specification, the "alkyl group" is a concept that includes a "cycloalkyl group."

[0027] R 3 is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, from the viewpoint of increasing the strength of the green sheet obtained by using the binder composition of the present invention and from the viewpoint of suppressing rapid thermal decomposition of the binder composition of the present invention in the temperature range of 300°C to 400°C during degreasing treatment.

[0028] Examples of the monomer (a-1) for forming the structural unit (a-1) of the copolymer (A) include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 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.

[0029] The monomer (a-1) for forming the structural unit (a-1) of the copolymer (A) is Preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, and cyclohexyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate.

[0030] The amount of the structural unit (a-1) in the copolymer (A) is preferably 70 to 97 mol %, more preferably 85 to 95 mol %, based on all structural units. By keeping the amount of the structural unit (a-1) within this range, a green sheet with good strength can be obtained.

[0031] R in equation (3) 4 is preferably a methyl group from the viewpoint of ease of polymerization of the monomer (a-2).

[0032] R in equation (3) 5 is a hydroxyalkyl group having 1 to 8 carbon atoms and having one or two hydroxyl groups. From the viewpoint of improving the uniformity of the resulting ceramic slurry and producing a ceramic molded body with high smoothness, R 5 Preferably, R has one hydroxyl group. 5 The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1 or 2.

[0033] Examples of the monomer (a-2) for forming the structural unit (a-2) of the copolymer (A) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and glycerin mono(meth)acrylate.

[0034] The monomer (a-2) for forming the structural unit (a-2) of the copolymer (A) is Preferably, it is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; More preferred is 2-hydroxyethyl (meth)acrylate.

[0035] The amount of the structural unit (a-2) in the copolymer (A) is preferably 3 to 30 mol %, more preferably 5 to 15 mol %. By ensuring that the amount of the structural unit (a-2) is within this range, the uniformity of the resulting ceramic slurry can be improved, and a ceramic molded body with excellent smoothness can be produced.

[0036] From the viewpoint of the strength and flexibility of the green sheet, the amount of component (A) must be 10 to 70 parts by mass per 100 parts by mass of the total of components (A) to (C). If the amount of component (A) is less than 10 parts by mass, the strength of the green sheet will be insufficient and the sheet will become brittle. If the amount of component (A) exceeds 70 parts by mass, the viscosity of the ceramic slurry will increase, making it difficult to form the green sheet. From the viewpoint of the strength, flexibility, and handleability of the green sheet, the amount of component (A) is preferably 20 to 70 parts by mass, more preferably 30 to 65 parts by mass, per 100 parts by mass of the total of components (A) to (C).

[0037] The method for producing component (A) can be selected from known methods such as suspension polymerization, solution polymerization, emulsion polymerization, etc. Among these polymerization methods, suspension polymerization is preferred because it is easy to obtain component (A) with a high molecular weight.

[0038] The polymerization initiator is not particularly limited, and examples thereof include peroxides such as benzoyl peroxide, azo initiators such as 2,2'-azobisisobutyronitrile, etc. These polymerization initiators may be used alone or in combination of two or more.

[0039] During polymerization, a chain transfer agent may be used to control the molecular weight of component (A). Examples of chain transfer agents include general-purpose compounds such as α-methylstyrene dimer and 1-thioglycerol.

[0040] <Ingredient (B)> The component (B) used in the present invention is a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 30,000 to 300,000.

[0041] The hydroxyl value of component (B) must be 5 to 50 mgKOH / g. If the hydroxyl value of component (B) is less than 5 mgKOH / g, the ceramic slurry will be poorly dispersed. If the hydroxyl value of component (B) exceeds 50 mgKOH / g, aggregation will occur during polymerization of component (B), making the polymerization difficult. From the viewpoints of dispersibility of the ceramic slurry and stability during polymerization of component (B), the hydroxyl value of component (B) is preferably 5 to 40 mgKOH / g, more preferably 10 to 30 mgKOH / g.

[0042] The weight-average molecular weight of component (B) of the present invention must be 30,000 to 300,000. If the weight-average molecular weight of component (B) is less than 30,000, the strength of the green sheet obtained using the binder composition of the present invention will be insufficient, and the dispersion stability of the ceramic slurry obtained from the binder composition of the present invention will be reduced. Furthermore, if the weight-average molecular weight of component (B) exceeds 300,000, the ceramic slurry obtained using the binder composition of the present invention will be prone to stringiness, impairing the surface smoothness of the ceramic molded body (especially the green sheet). From the viewpoints of the handleability of the ceramic slurry and the surface smoothness of the green sheet, the weight-average molecular weight of component (B) is preferably 30,000 to 250,000, more preferably 50,000 to 200,000. The weight-average molecular weight of component (B) can be determined in terms of polystyrene using gel permeation chromatography (GPC).

[0043] The glass transition temperature of component (B) is preferably 0 to 80°C. If the glass transition temperature of component (B) is less than 0°C, the surface of the green sheet becomes sticky and difficult to handle. If the glass transition temperature of component (B) exceeds 80°C, segregation of the ceramic slurry may occur, resulting in a deterioration in the stability of the ceramic slurry. From the viewpoint of the handleability of the green sheet and the stability of the ceramic slurry, the glass transition temperature of component (B) is more preferably 20 to 70°C, and even more preferably 40 to 60°C.

[0044] From the viewpoint of dispersion stability of the ceramic slurry, component (B) is preferably a (meth)acrylic polymer containing hydroxyl group-containing structural units in an amount of 3 to 30 mol % based on all structural units. From the viewpoint of stability during polymerization of component (B), the amount of hydroxyl group-containing structural units in component (B) is more preferably 5 to 15 mol % based on all structural units.

[0045] Component (B) is preferably a copolymer containing structural units (a-1) and (a-2), in which the amount of structural units (a-1) is 70 to 97 mol % and the amount of structural units (a-2) is 3 to 30 mol % of the total structural units (hereinafter sometimes referred to as "copolymer (B)"). The hydroxyl value, weight average molecular weight, and glass transition temperature of copolymer (B) are the same as those described above for component (B).

[0046] Examples of the monomer (a-1) for forming the structural unit (a-1) of the copolymer (B) include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 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.

[0047] The monomer (a-1) for forming the structural unit (a-1) of the copolymer (B) is Preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, and cyclohexyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of (meth)acrylic acid, methyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate.

[0048] Examples of the monomer (a-2) for forming the structural unit (a-2) of the copolymer (B) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and glycerin mono(meth)acrylate.

[0049] The monomer (a-2) for forming the structural unit (a-2) of the copolymer (B) is Preferably, it is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate; More preferably, it is at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; More preferred is 2-hydroxyethyl (meth)acrylate.

[0050] The amount of the structural unit (a-1) in the copolymer (B) is preferably 70 to 97 mol %, more preferably 85 to 95 mol %, based on all structural units. By keeping the amount of the structural unit (a-1) within this range, a green sheet with good strength can be obtained.

[0051] The amount of the structural unit (a-2) in the copolymer (B) is 3 to 30 mol %, and preferably 5 to 15 mol %. By ensuring that the amount of the structural unit (a-2) is within this range, the uniformity of the resulting ceramic slurry can be improved, and a ceramic molded body with excellent smoothness can be produced.

[0052] From the viewpoint of the strength and flexibility of the green sheet, the amount of component (B) must be 10 to 40 parts by mass per 100 parts by mass of the total of components (A) to (C). If the amount of component (B) is less than 10 parts by mass, the green sheet will lack flexibility and will be difficult to process. If the amount of component (B) exceeds 40 parts by mass, the green sheet will lack strength and become brittle. From the viewpoint of the strength and flexibility of the green sheet, the amount of component (B) is preferably 10 to 30 parts by mass per 100 parts by mass of the total of components (A) to (C).

[0053] The method for producing component (B) can be selected from known methods such as suspension polymerization, solution polymerization, emulsion polymerization, etc. Among these polymerization methods, suspension polymerization is preferred because it is easy to obtain component (B) with the desired molecular weight.

[0054] The polymerization initiator is not particularly limited, and examples thereof include peroxides such as benzoyl peroxide, azo initiators such as 2,2'-azobisisobutyronitrile, etc. These polymerization initiators may be used alone or in combination of two or more.

[0055] During polymerization, a chain transfer agent may be used to control the molecular weight of component (B). Examples of the chain transfer agent include general-purpose compounds such as α-methylstyrene dimer and 1-thioglycerol.

[0056] <Mass ratio of the amount of component (A) / the amount of component (B)> The mass ratio of the amount of component (A) to the amount of component (B) must be 40 / 60 to 85 / 15. If this mass ratio is less than 40 / 60, the strength of the ceramic molded body (particularly the green sheet) formed using the binder composition of the present invention will be insufficient, and the smoothness of the molded body will be impaired. If this mass ratio exceeds 85 / 15, the extensibility of the green sheet obtained using the binder composition of the present invention will be impaired. The mass ratio is preferably 50 / 50 to 80 / 20, and more preferably 60 / 40 to 80 / 20.

[0057] <Component (C)> The component (C) used in the present invention is a compound represented by the formula (1): R 1 O-(EO) p -(PO) q -H (1) (In the formula, R 1 represents an alkyl group having 5 to 9 carbon atoms, EO represents an oxyethylene group; PO represents an oxypropylene group; p is a number between 3 and 9, q is a number between 2 and 4, and p / q is in the range of 1.0 to 3.0.) The component (C) may be used alone or in combination of two or more.

[0058] R in formula (1) 1 is an alkyl group having 5 to 9 carbon atoms. From the viewpoint of the compatibility of component (A), component (B) and component (C), and the extensibility of the green sheet, R 1 is preferably branched.

[0059] Examples of the alkyl group having 5 to 9 carbon atoms include a nonyl group, an isononyl group, and a 3,5,5-trimethyl-1-hexyl group. 1 is preferably an isononyl group or a 3,5,5-trimethyl-1-hexyl group, more preferably an isononyl group.

[0060] In formula (1), p is the number of oxyethylene groups (i.e., the average number of moles of ethylene oxide added per mole of starting material when synthesizing component (C)). Therefore, p may be a decimal number. p is a number from 3 to 9. If p is less than 3, the compatibility of component (A) and component (B) with component (C) may decrease, and the flexibility and extensibility of a ceramic molded body formed using the binder composition of the present invention may decrease. On the other hand, if p is greater than 9, the thermal decomposition of the binder composition of the present invention may not proceed easily up to around 300°C during the degreasing treatment, and the thermal decomposition of the binder composition of the present invention may proceed rapidly in the temperature range from 300°C to 400°C. p is preferably a number from 5 to 9, more preferably a number from 7 to 8.

[0061] In formula (1), q is the number of oxypropylene groups (i.e., the average number of moles of propylene oxide added per mole of the starting material when synthesizing component (C)). Therefore, q may be a decimal number. q is a number from 2 to 4. If q is less than 2, the compatibility of component (C) with the organic solvent of the ceramic slurry decreases, the ceramic slurry becomes non-uniform, and the smoothness of the resulting ceramic molded body decreases. If q is more than 4, the compatibility of component (A) and component (B) with component (C) decreases, and the flexibility and extensibility of the ceramic molded body formed using the binder composition of the present invention may decrease. q is preferably 3.

[0062] The ratio p / q is within the range of 1.0 to 3.0. If the ratio p / q is less than 1.0, the compatibility of component (A) and component (B) with component (C) may decrease, resulting in a decrease in the flexibility and extensibility of the ceramic molded body formed using the binder composition of the present invention. On the other hand, if the ratio p / q is greater than 3.0, the compatibility of component (C) with the organic solvent of the ceramic slurry may decrease, resulting in a non-uniform ceramic slurry and a decrease in the smoothness of the ceramic molded body. Furthermore, if the ratio p / q is greater than 3.0, the oxyethylene groups may be relatively too high, which may hinder the thermal decomposition of the binder composition of the present invention and reduce degreasing properties. The ratio p / q is preferably within the range of 1.6 to 3.0, more preferably within the range of 2.4 to 3.0.

[0063] The amount of component (C) must be 1 to 50 parts by mass per 100 parts by mass of the total of components (A) to (C). If the amount of component (C) is less than 1 part by mass, the stability of the ceramic slurry formed using the binder composition of the present invention will be insufficient. If the amount of component (C) exceeds 50 parts by mass, the strength of the ceramic molded body (particularly the green sheet) obtained using the binder composition of the present invention will be insufficient, and the smoothness of the molded body will be impaired. The amount of component (C) is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, per 100 parts by mass of the total of components (A) to (C).

[0064] Component (C) can be produced, for example, by adding ethylene oxide corresponding to EO to an alcohol starting material, and then adding propylene oxide corresponding to PO. The addition of alkylene oxides is well known to those skilled in the art, and those skilled in the art can produce component (C) by appropriately setting the addition conditions.

[0065] <Organic solvents> The binder composition of the present invention may contain an organic solvent as a component different from components (A) to (C). The organic solvent may be used alone or in combination of two or more. From the viewpoint of the sheet formability of the ceramic slurry, the organic solvent is preferably a highly volatile organic solvent. Examples of highly volatile organic solvents include methanol, ethanol, toluene, acetone, and methyl ethyl ketone. The organic solvent is more preferably at least one selected from the group consisting of ethanol and toluene.

[0066] <Ceramics slurry> The present invention also provides a ceramic slurry containing the binder composition of the present invention, a ceramic powder, a dispersant, and an organic solvent. The ceramic powder, dispersant, and organic solvent may be used alone or in combination of two or more.

[0067] The ceramic powder may be either an oxide ceramic powder or a non-oxide ceramic powder. Examples of oxide ceramic powders include alumina, titania, zirconia, barium titanate, and lead zirconate titanate. Examples of non-oxide ceramic powders include silicon carbide and silicon nitride. The ceramic powder is preferably silicon nitride.

[0068] The volume-based median diameter d of ceramic powder measured using a laser diffraction / scattering particle size distribution analyzer 50 From the viewpoint of dispersibility of the ceramic slurry, the particle size is preferably 0.05 to 50.0 μm, more preferably 0.10 to 10.0 μm, still more preferably 0.20 to 5.00 μm, and particularly preferably 0.20 to 1.50 μm.

[0069] The dispersant is not particularly limited, and any of cationic dispersants, anionic dispersants, nonionic dispersants, and amphoteric dispersants can be used. Polymer dispersants may also be used.

[0070] 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 sulfonate ester-based dispersants. Examples of nonionic dispersants include polyethylene glycol-based dispersants. Examples of polymer-based dispersants include polymeric polycarboxylic acid-based dispersants. The dispersant is preferably a polymeric dispersant, and more preferably a polymeric polycarboxylic acid-based dispersant.

[0071] From the viewpoint of the sheet formability of the ceramic slurry, the organic solvent is preferably a highly volatile organic solvent. Examples of highly volatile organic solvents include methanol, ethanol, toluene, acetone, and methyl ethyl ketone. The organic solvent is more preferably at least one selected from the group consisting of ethanol and toluene.

[0072] From the viewpoint of ceramic slurry stability, it is preferable that the total amount of components (A) to (C) is 5 to 100 parts by mass, the amount of dispersant is 0.1 to 10 parts by mass, and the amount of organic solvent is 10 to 500 parts by mass per 100 parts by mass of ceramic powder. The total amount of components (A) to (C) is 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. The amount of dispersant is 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. The amount of organic solvent is 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.

[0073] <Other ingredients> The ceramic slurry of the present invention may contain other components different from the binder composition, ceramic powder, dispersant, and organic solvent of the present invention, as long as the effects of the present invention are not impaired. The other components may be used alone or in combination of two or more. Examples of the other components include an antifoaming agent.

[0074] <Method of manufacturing ceramic molded body> There is no particular limitation on the method for producing a ceramic molded body (e.g., a green sheet) from the ceramic slurry of the present invention, and known methods include, for example, press molding and sheet molding.

[0075] The support used in the sheet molding method is not particularly limited, and known supports can be used, such as polyethylene terephthalate, polycarbonate, stainless steel (SUS), and glass plate.

[0076] The method for drying the ceramic slurry applied to the support is not particularly limited, and drying can be performed by a known method. Examples of dryers include a drying furnace and a hot dryer. The drying atmosphere may be air or an inert gas atmosphere such as nitrogen gas. The drying pressure may be normal pressure or reduced pressure. The drying temperature and time vary depending on the components of the ceramic slurry. Drying may be performed by increasing the drying temperature in stages. For example, the ceramic slurry applied to the support may be dried at room temperature for 30 minutes to 2 hours, then at 30 to 50°C for 30 minutes to 2 hours, and then at 80 to 120°C for 1 to 3 hours. It is preferable to apply the ceramic slurry to the support so that the thickness of the green sheet obtained after drying is 0.5 to 300 μm.

[0077] The resulting green sheet can be subjected to a degreasing treatment to remove organic components, thereby producing a dielectric layer or the like. There are no particular limitations on the degreasing method, and any known method can be used. For example, the organic components can be removed by heat treating the green sheet in an inert gas atmosphere using an electric furnace or the like at 350 to 500°C for 30 to 150 minutes. [Example]

[0078] The present invention will be described below in more detail with reference to examples, although the present invention is not limited to the following examples.

[0079] <abbreviation> The abbreviations used in the table below have the following meanings: BMA: butyl methacrylate IBMA: isobutyl methacrylate MAA: methacrylic acid MMA: methyl methacrylate HEMA: 2-hydroxyethyl methacrylate INA: Isononanol

[0080] <Synthesis of component (A)> (Synthesis Example 1: Synthesis of Component (A-1)) A 1 L separable flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 600 g of ion-exchanged water and 6.0 g of polyvinyl alcohol (Kuraray Co., Ltd., "Poval PVA-224E") and heated with stirring to prepare an aqueous solution. To this aqueous solution, a mixture of 190.8 g of isobutyl methacrylate as monomer (a-1), 9.2 g of 2-hydroxyethyl methacrylate as monomer (a-2), 1.2 g of NOF Corporation's "Perloyl OPP" as a polymerization initiator, and 0.6 g of NOF Corporation's "Nofumer MSD" (α-methylstyrene dimer) as a chain transfer agent was added and heated at 50 °C for 3 hours to obtain a particulate copolymer. The mixture containing the particulate copolymer was then heated to 70 °C and stirred at 70 °C for 2 hours to completely decompose the initiator. The mixture was then cooled to room temperature and filtered to obtain a wet particulate copolymer. The wet granular copolymer was spread on an aluminum tray, and the tray was placed in a thermostatic oven at 40°C to thoroughly remove the moisture, yielding a granular copolymer, component (A-1).

[0081] (Synthesis Example 2: Synthesis of Component (A-2)) A copolymer, component (A-2), was obtained in the same manner as in Synthesis Example 1, except that the amount of isobutyl methacrylate used as monomer (a-1) was changed to 212.4 g, the amount of 2-hydroxyethyl methacrylate used as monomer (a-2) was changed to 21.6 g, 166.0 g of methyl methacrylate was used as monomer (a-1), and the amount of perloyl OPP used as the polymerization initiator was changed to 3.45 g.

[0082] [Hydroxyl value] The hydroxyl values of the copolymers obtained in Synthesis Examples 1 and 2 (ie, components (A-1) and (A-2)) were determined by measurement in accordance with JIS K 0070-1992.

[0083] [Weight average molecular weight (Mw)] The Mw of the copolymers obtained in Synthesis Examples 1 and 2 (ie, components (A-1) and (A-2)) was determined by gel permeation chromatography (GPC) under the following conditions. Equipment: Tosoh HLC-8220 Column: Shodex, KF-805L Standard material: polystyrene Eluent: THF (tetrahydrofuran) Flow rate: 1.0ml / min Column temperature: 40℃ Detector: RI (differential refractive index detector)

[0084] [Glass transition temperature (Tg)] Using the above formula (I), the glass transition temperatures (Tg) of the copolymers obtained in Synthesis Examples 1 and 2 (i.e., components (A-1) and (A-2)) were calculated. For the calculation, a value of 378 K was used as the glass transition temperature of a homopolymer of methyl methacrylate, a value of 326 K as the glass transition temperature of a homopolymer of isobutyl methacrylate, and a value of 328 K as the glass transition temperature of 2-hydroxyethyl methacrylate were used. In Table 1 below, Tg is shown as a converted value in Celsius temperature (°C) rather than a calculated value in absolute temperature (K).

[0085] Table 1 shows the types and amounts of monomers used in the synthesis of the copolymers obtained in Synthesis Examples 1 and 2 (i.e., components (A-1) and (A-2)), as well as the hydroxyl values, Mw, and Tg (°C) of these copolymers, and the amounts (mol %) of monomer (a-1) and monomer (a-2) used relative to all monomers (referred to as "amount (mol %) of monomer (a-1)" and "amount (mol %) of monomer (a-2)," respectively, in Table 1).

[0086] [Table 1]

[0087] <Synthesis of component (B) or component (B')> (Synthesis Example 3: Synthesis of Component (B-1)) A copolymer, component (B-1), was obtained in the same manner as in Synthesis Example 1, except that the amount of initiator perloyl OPP used was changed to 4.9 g.

[0088] (Synthesis Example 4: Synthesis of Component (B-2)) The copolymer component (B-2) was obtained in the same manner as in Synthesis Example 1, except that the amount of isobutyl methacrylate used as monomer (a-1) was changed to 14.6 g, 80.5 g of butyl methacrylate and 0.3 g of methacrylic acid were used as monomer (a-1), the amount of 2-hydroxyethyl methacrylate used as monomer (a-2) was changed to 4.6 g, the amount of Perloyl OPP used as the polymerization initiator was changed to 2.21 g, and the amount of Nofumer MSD used as the chain transfer agent was changed to 0.4 g.

[0089] (Synthesis Example 5: Synthesis of component (B'-1)) The copolymer component (B'-1) was obtained in the same manner as in Synthesis Example 1, except that the amount of isobutyl methacrylate (monomer (a-1)) used was changed to 100.0 g, the amount of Perloyl OPP (polymerization initiator) used was changed to 2.51 g, the amount of Nofumer MSD (chain transfer agent) used was changed to 0.4 g, and no monomer (a-2) was used.

[0090] [Hydroxyl value, weight average molecular weight (Mw), and glass transition temperature (Tg)] The hydroxyl value, Mw, and Tg of the copolymers obtained in Synthesis Examples 3 to 5 (i.e., components (B-1), (B-2), and (B'-1)) were determined using the same methods as above. To calculate the glass transition temperatures (Tg) of components (B-1) and (B-2), the following values were used: 326 K for the glass transition temperature of a homopolymer of isobutyl methacrylate, 293 K for the glass transition temperature of a homopolymer of butyl methacrylate, 501 K for the glass transition temperature of a homopolymer of methacrylic acid, and 328 K for the glass transition temperature of 2-hydroxyethyl methacrylate. In Table 2 below, the Tg values are shown converted to Celsius temperature (°C) rather than calculated values in absolute temperature (K).

[0091] Table 2 shows the types and amounts of monomers used in the synthesis of the polymers obtained in Synthesis Examples 3 to 5 (i.e., components (B-1), (B-2), and (B'-1)), as well as the hydroxyl values, Mw, and Tg (°C) of these polymers, and the amounts (mol %) of monomer (a-1) and monomer (a-2) used relative to all monomers (referred to as "amount (mol %) of monomer (a-1)" and "amount (mol %) of monomer (a-2)," respectively, in Table 2).

[0092] [Table 2]

[0093] <Synthesis of component (C)> (Synthesis Example 6: Synthesis of Component (C-1)) A 5-L autoclave was charged with 433 g of isononanol (KH Neochem "Oxocol 900") and 10 g of potassium hydroxide. After purging with nitrogen, the mixture was heated to 120°C with stirring. Next, 1,058 g of ethylene oxide was added dropwise over 6 hours using a dropping device, and the mixture was allowed to react for an additional hour at 120°C. Subsequently, 523 g of propylene oxide was added dropwise over 4 hours using a dropping device, and the mixture was allowed to react for an additional hour at 120°C. The crude product was then removed from the autoclave and neutralized with hydrochloric acid to a pH of 6-7 as measured in accordance with JIS K1557-5. Next, to remove water from the crude product derived from the hydrochloric acid, the neutralized crude product was subjected to reduced pressure treatment at 100°C for 1 hour. Finally, the salt was removed by filtration, yielding 1,913 g of the copolymer component (C-1).

[0094] Table 3 shows the starting materials for the copolymer obtained in Synthesis Example 6 (i.e., component (C-1)), as well as the R 1 , p, q, and p / q are written.

[0095] [Table 3]

[0096] (Examples 1 to 6 and Comparative Examples 1 to 6) <Production of binder composition> Components (A) to (C) obtained in the above synthesis examples were mixed in the combinations and ratios shown in Tables 4 and 5. A binder composition was produced by mixing 5 parts by mass of toluene and 5 parts by mass of ethanol with a total of 10 parts by mass of components (A) and (B).

[0097] <Production of ceramic slurry> Silicon nitride ceramic powder (manufactured by Denka Co., Ltd.: "SN-9S"), with a volume-based median diameter d 5015 parts by mass of a polymeric polycarboxylic acid dispersant (NOF Corporation: "Marialim AKM-0531"), 0.6 parts by mass of a polymeric polycarboxylic acid dispersant, and 15 parts by mass of zirconia balls with a particle size of 1 mm were placed in a ball mill and mixed for 8 hours. Then, 10 parts by mass of the binder composition prepared above was added and mixed for a further 48 hours. The zirconia balls were then filtered off to produce a ceramic slurry.

[0098] <Green sheet manufacturing> The obtained ceramic slurry was applied in sheet form onto a PET film using a film applicator, and then dried at room temperature for 1 hour, then at 40°C for 1 hour, and then at 100°C for 2 hours to produce a green sheet (thickness: 0.1 mm).

[0099] [Sheet strength test] From the obtained green sheet, a rectangular test piece having a thickness of 0.1 mm, a length of 60 mm, and a width of 20 mm was cut out, and a tensile test was carried out 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 is 4.50N / mm 2 End ○: Tensile strength is 4.00N / mm 2 More than 4.50N / mm 2 less than △: Tensile strength is 4.00N / mm 2 less than

[0100] [Sheet extensibility test] Test pieces were prepared and tensile tests were carried out in the same manner as in the sheet strength test described above, and the elongation at break (%) (= 100 × (L − L) / L, where L is the gauge length and L is the gauge length at break) was measured, and the sheet extensibility was evaluated according to the following criteria. ◎: Breaking elongation is 3.50% or more ○: Breaking elongation is 3.00% or more and less than 3.50% △: Breaking elongation is less than 3.00%

[0101] [Crack test for thick films] A green sheet with a thickness of 0.1 mm, a width of 5 cm, and a length of 10 cm was dried at 80°C for 3 hours, and the number of cracks on the dried green sheet was visually counted, and the cracks in the thick film were evaluated according to the following criteria. ◎: No cracks 〇: Number of cracks: 1 to 3 △: Number of cracks is 4 or more

[0102] [Thick film flexibility test] A green sheet having a thickness of 0.1 mm, a width of 1 cm, and a length of 9 cm was wrapped around a glass rod having a diameter of 20 mm, and the number of cracks in the green sheet was visually counted, and the flexibility of the thick film was evaluated according to the following criteria. ◎: No cracks 〇: Number of cracks: 1 to 3 △: Number of cracks is 4 or more

[0103] [Dispersion stability test] 30 mL of the obtained ceramic slurry was weighed into a 50 mL transparent glass bottle. The transparent glass bottle containing the ceramic slurry was then left to stand in an environment with an ambient temperature of 23°C and 50% RH. The state of the ceramic slurry that had been left to stand was visually observed over time, and the period from the time of standing until no sediment was observed (hereinafter referred to as the "stable period") was measured, and its dispersion stability was evaluated according to the following criteria. ◎: Stable period of 3 days or more 〇: Stable period is 1 day or more but less than 3 days △: Stable period is less than 1 day

[0104] The evaluation results of the ceramic slurries of Examples 1 to 6 and Comparative Examples 1 to 6 (i.e., tensile strength and the resulting green sheet strength, breaking elongation and the resulting green sheet extensibility, the presence or absence of cracks and flexibility when formed into a thick film, and slurry stability) are shown in Tables 4 and 5.

[0105] [Table 4]

[0106] [Table 5]

[0107] As shown in Table 4, the ceramic slurries of Examples 1 to 6 showed good results in all evaluations.

[0108] On the other hand, as shown in Table 5, the ceramic slurries of Comparative Examples 1 and 2, in which component (B') without hydroxyl groups was used instead of component (B), had insufficient cracking and flexibility of the thick film.

[0109] The ceramic slurries of Comparative Examples 3 and 4, in which the amount of component (B) was excessive, were insufficient in terms of sheet strength, cracking of the thick film, and flexibility of the thick film.

[0110] The ceramic slurries of Comparative Examples 5 and 6, which contained an excessive amount of component (B) and did not contain component (C), were insufficient in sheet strength, sheet extensibility, thick film cracking, thick film flexibility, and dispersion stability. [Industrial Applicability]

[0111] The binder composition and ceramic slurry of the present invention are useful for producing ceramic molded bodies (particularly green sheets).

Claims

1. The following components (A) to (C): (A) a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 400,000 to 1,000,000; (B) a (meth)acrylic polymer having a hydroxyl value of 5 to 50 mgKOH / g and a weight average molecular weight of 30,000 to 300,000; and (C) Formula (1): 2 １ 9-(59) ｐ -(0) ｑ -2 (1) (In the formula, R １ represents an alkyl group having 5 to 9 carbon atoms, EO represents an oxyethylene group; PO represents an oxypropylene group; p is a number from 3 to 9, q is a number from 2 to 4, and p / q is in the range of 1.0 to 3.

0. A copolymer represented by A ceramic molding binder composition comprising: The amount of component (A) is 10 to 70 parts by mass, the amount of component (B) is 10 to 40 parts by mass, and the amount of component (C) is 1 to 50 parts by mass, relative to 100 parts by mass in total of components (A) to (C); and A ceramic molding binder composition, wherein the mass ratio of the amount of component (A) to the amount of component (B) is within the range of 40 / 60 to 85 / 15.

2. 2. The ceramic molding binder composition according to claim 1, wherein component (A) is a (meth)acrylic polymer containing structural units derived from monomers having a hydroxyl group in an amount of 3 to 30 mol % based on all structural units.

3. 2. The ceramic molding binder composition according to claim 1, wherein component (B) is a (meth)acrylic polymer containing structural units derived from monomers having a hydroxyl group in an amount of 3 to 30 mol % based on all structural units.

4. A ceramic slurry comprising the ceramic molding binder composition according to any one of claims 1 to 3, ceramic powder, a dispersant, and an organic solvent.

5. 5. The ceramic slurry according to claim 4, wherein the total amount of components (A) to (C) is 5 to 100 parts by mass, the amount of dispersant is 0.1 to 10 parts by mass, and the amount of organic solvent is 10 to 500 parts by mass, relative to 100 parts by mass of ceramic powder.

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