Binder composition for firing and slurry for firing

Abstract

To provide a binder composition for firing that enhances the strength of a green sheet formed from a slurry for firing containing the binder composition for firing, without impairing the thermal degradability and while ensuring slurry stability to be prepared.SOLUTION: A binder composition for firing comprises an acrylic polymer (A) and a polyfunctional amine compound (B). The acrylic polymer (A) has a repeating unit (a1) represented by the following formula (I). In formula (I), R1 is a hydrogen atom or a methyl group, and R2 is a methylene group, an ethylene group, or an ethoxyethylene group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure generally relates to a binder composition for firing and a slurry for firing, and more particularly, to a binder composition for firing containing an acrylic polymer and a slurry for firing containing the binder composition for firing. [Background technology]

[0002] Patent Document 1 discloses a composition containing an acrylic copolymer obtained by copolymerizing a monomer having an acetoacetoxyethyl group with another ethylenically unsaturated monomer, and a crosslinking agent. It also describes that an isocyanate-based crosslinking agent is preferable as the crosslinking agent. It also discloses that an oxide film of this composition is prepared and laminated on a plastic substrate to produce a laminated film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-225703 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a film can be produced by using a specific acrylic copolymer and a crosslinking agent, but there is no description of a binder composition used for firing and its use as a slurry. When used as a binder for firing, the binder composition is required to have thermal decomposition properties, and when a green sheet is produced from the binder composition and slurry for firing, the green sheet is also required to have high strength. In addition, it is said that conventional binder compositions for firing have room for further improvement in terms of slurry stability.

[0005] An object of the present disclosure is to provide a sintering binder composition that can ensure the stability of the prepared slurry and increase the strength of a green sheet produced from a sintering slurry containing the sintering binder composition without impairing thermal decomposition, and a sintering slurry containing this sintering binder composition. [Means for solving the problem]

[0006] The binder composition for firing according to one embodiment of the present disclosure contains an acrylic polymer (A) and a polyfunctional amine compound (B). The acrylic polymer (A) has a repeating unit (a1) represented by the following formula (I): In the formula (I), R1 is a hydrogen atom or a methyl group, and R2 is a methylene group, an ethylene group, or an ethoxyethylene group.

[0007] [ka]

[0008] A slurry for firing according to one embodiment of the present disclosure contains the binder composition for firing and an inorganic powder. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a sintering binder composition that can ensure the stability of the prepared slurry and increase the strength of a green sheet produced from a sintering slurry containing the sintering binder composition without impairing thermal decomposition, and a sintering slurry containing this sintering binder composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of the present disclosure will be described. Note that the following embodiment is merely one of various embodiments of the present disclosure, and the present disclosure can be modified in various ways depending on the design.

[0011] 1. Overview The inventors have conducted research and development to further improve the strength of the green sheet in order to further improve the handling of the green sheet while maintaining the thermal decomposition of the binder composition for firing. In the process, they have concluded that introducing a crosslinked structure into the binder resin is effective in improving the strength of the sheet. However, it has been found that there is a problem that the slurry after preparation is gelled by adding a crosslinking agent when preparing a slurry from the binder composition for firing, and the green sheet cannot be produced well. That is, it has been found that in the process of preparing the binder composition for firing and producing the slurry, the acrylic polymer and the crosslinking agent react quickly after preparation, which can cause gelling or excessive viscosity before the sheet is produced. Therefore, there is a problem that the workability is deteriorated and it becomes difficult to produce a good green sheet in the first place.

[0012] Therefore, the inventors have conducted extensive research to solve the above problems, and have arrived at the configuration of the binder composition for firing and the slurry for firing of the present disclosure.

[0013] The binder composition for firing of this embodiment contains an acrylic polymer (A) and a polyfunctional amine compound (B). The acrylic polymer (A) has a repeating unit (a1) represented by the following formula (I). In formula (I), R1 is a hydrogen atom or a methyl group, and R2 is a methylene group, an ethylene group, or an ethoxyethylene group.

[0014] [ka]

[0015] According to the binder composition for firing of the present embodiment, the stability of the prepared slurry can be ensured, and the strength of the green sheet produced from the slurry for firing containing the binder composition for firing can be easily increased without impairing the thermal decomposition property.

[0016] Specifically, in the binder composition for firing, the acetoacetoxy structure in the repeating unit (a1) reacts with the amino group in the polyfunctional amine compound (B) to form an imine bond or an enamine bond. Therefore, when a slurry for firing is prepared from the binder composition for firing and a green sheet is produced from the slurry for firing, a crosslinked structure due to an imine bond or an enamine bond is formed in the green sheet, which is considered to realize high strength of the green sheet. The reaction system between the acrylic copolymer (A) and the polyfunctional amine compound (B) will be described in detail later.

[0017] On the other hand, the formation of the above-mentioned imine bond or enamine bond is likely to occur during the process of preparing a green sheet, i.e., after the volatile components such as the solvent are evaporated by preparing the firing slurry, or during the volatilization process, and is unlikely to occur during the preparation of the firing binder composition and the firing slurry. The reason for this is thought to be that the crosslinking reaction is unlikely to proceed at room temperature, and the reaction proceeds due to heating and drying during sheet molding. Therefore, when preparing the firing slurry from the firing binder composition, gelation is unlikely to occur, and the storage stability of the firing slurry can be maintained relatively high. As a result, the firing slurry of this embodiment is unlikely to become highly viscous and has excellent workability.

[0018] 2.Details [Binder composition for firing] As described above, the binder composition for firing of the present embodiment contains the acrylic polymer (A) and the polyfunctional amine compound (B). Hereinafter, components that can be contained in the binder composition for firing will be specifically described.

[0019] (Acrylic polymer) The acrylic polymer (A) according to this embodiment is blended in a binder composition for firing. The acrylic polymer (A) is synthesized by polymerizing a polymerizable unsaturated monomer including a (meth)acrylic compound. A (meth)acrylic compound is a compound having a (meth)acryloyl group. In this disclosure, "(meth)acrylic" means at least one of "acrylic" and "methacrylic", that is, it is a higher-level concept of "acrylic" and "methacrylic".

[0020] The acrylic polymer (A) is a polymer of one or more polymerizable unsaturated monomers. That is, the acrylic polymer (A) is obtained by polymerizing one or more polymerizable unsaturated monomers. The acrylic polymer (A) may contain a copolymer of two or more polymerizable unsaturated monomers in addition to a copolymer of one polymerizable unsaturated monomer. In the present disclosure, the "repeating unit" refers to a structure derived from each of one or more polymerizable unsaturated monomers in the copolymer. Therefore, the structure of each repeating unit that the acrylic polymer (A) may have is derived from the structure of the corresponding polymerizable unsaturated monomer.

[0021] In this embodiment, the acrylic polymer (A) has a repeating unit (a1) represented by formula (I).

[0022] [ka]

[0023] In formula (I), R1 is a hydrogen atom or a methyl group, and R2 is a methylene group, an ethylene group, or an ethoxyethylene group.

[0024] According to this embodiment, by blending this acrylic polymer (A) in the binder composition for firing, the strength of the green sheet made from the slurry for firing containing the binder composition for firing can be increased without impairing the thermal decomposition property of the binder composition for firing. Furthermore, the acrylic polymer (A) of this embodiment can maintain the stability of the slurry of the binder composition for firing well even when the binder composition for firing is prepared together with the polyfunctional amine compound (B).

[0025] As shown in formula (I), the repeating unit (a1) has an acetoacetoxy skeleton of -O-CO-CH2-CO-CH3. Specifically, the repeating unit (a1) has a β-ketoester structure derived from a β-dicarbonyl compound at its terminal. Therefore, when the acrylic polymer (A) reacts with the polyfunctional amine compound (B), the carbonyl group at the α-position of the acetoacetoxy skeleton reacts with the amino group of the polyfunctional amine compound (B) to form an enamine skeleton.

[0026] Examples of the polymerizable unsaturated monomer that can provide the repeating unit (a1) include at least one monomer selected from the group consisting of 2-((meth)acryloyloxy)methyl acetoacetate, 2-((meth)acryloyloxy)ethyl acetoacetate, and 2-((meth)acryloyloxy)ethoxyethyl acetoacetate.

[0027] The percentage of the repeating unit (a1) is preferably 2% by mass or more and 20% by mass or less with respect to the acrylic polymer (A). If the percentage of the repeating unit (a1) is 2% by mass or more, the hardness of the green sheet can be increased, and if this percentage is 20% by mass or less, the green sheet has appropriate strength and smoothness, and the viscosity increase of the slurry can be suppressed. Therefore, the strength of the green sheet can be increased by the repeating unit (a1). The percentage of this repeating unit (a1) is more preferably 2.5% by mass or more, and even more preferably 5% by mass or more. Moreover, the percentage of this repeating unit (a1) is more preferably 17.5% by mass or less, and even more preferably 15% by mass or less.

[0028] The acrylic polymer (A) preferably further contains a repeating unit (a2) represented by formula (II).

[0029] [ka]

[0030] In formula (II), R3 is a hydrogen atom or a methyl group, and R4 is a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms.

[0031] When the acrylic polymer (A) has a repeating unit (a2) represented by formula (II) in addition to the repeating unit (a1) represented by formula (I), the repeating unit (a2) can provide the acrylic polymer (A) with better properties as a binder, such as moldability and thermal decomposition property.

[0032] Examples of the polymerizable unsaturated monomer that can provide the repeating unit (a2) include at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, lauryl (meth)acrylate, i-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0033] The percentage of the repeating unit (a2) is preferably 5% by mass or more and 95% by mass or less, for example, relative to the acrylic polymer (A). The percentage of the repeating unit (a2) is more preferably 10% by mass or more, and even more preferably 15% by mass or more. The percentage of the repeating unit (a2) is more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0034] The acrylic polymer (A) preferably further has a repeating unit (a3) ​​which is a residue of a polymerizable unsaturated monomer having a carboxyl group. In this case, the affinity between the acrylic polymer (A) and the inorganic powder in the sintering slurry can be increased, so that the sintering slurry can be easily formed into a sheet and the strength of the green sheet can be further increased. The repeating unit (a3) ​​is obtained by polymerizing an unsaturated monomer having a carboxyl group.

[0035] The repeating unit (a3) ​​is preferably a repeating unit represented by formula (III).

[0036] [ka]

[0037] In formula (III), R5 is a hydrogen atom or a methyl group, and R6 is a hydrogen atom or a substituent represented by formula (IV) or formula (V).

[0038] [ka]

[0039] [ka]

[0040] In formula (IV), R7 is a methylene group or an ethylene group, and R8 is a methylene group or an ethylene group. In formula (V), the value of n is within the range of 1 or more and 10 or less.

[0041] When the acrylic polymer (A) has a repeating unit (a3) ​​in addition to the repeating unit (a1) represented by formula (I), if the repeating unit (a3) ​​has a structure represented by formula (III), the affinity between the acrylic polymer (A) and the inorganic powder in the firing slurry can be further increased. As a result, the firing slurry can be easily formed into a sheet, and the strength of the green sheet can be particularly increased.

[0042] Examples of the polymerizable unsaturated monomer that can provide the repeating unit (a3) ​​include at least one monomer selected from the group consisting of (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, and ω-carboxypolycaprolactone (meth)acrylate.

[0043] When the acrylic polymer (A) has the repeating unit (a3), the percentage of the repeating unit (a3) ​​is preferably 1% by mass or more and 10% by mass or less based on the acrylic polymer (A). The percentage of the repeating unit (a3) ​​is more preferably 2% by mass or more. The percentage of the repeating unit (a3) ​​is more preferably 5% by mass or less.

[0044] The acrylic polymer (A) preferably further contains a repeating unit (a4) which is a residue of a polymerizable unsaturated monomer containing a hydroxyl group. In this case, the affinity between the acrylic polymer (A) and the inorganic powder in the sintering slurry can be increased, and the intramolecular interaction can be increased, so that the sintering slurry can be easily formed into a sheet, and the strength of the green sheet can be further increased. The acrylic polymer (A) having the repeating unit (a4) can be obtained by polymerizing an unsaturated monomer containing a hydroxyl group.

[0045] The repeating unit (a4) is preferably a repeating unit represented by formula (VI).

[0046] [ka]

[0047] In formula (VI), R is a hydrogen atom or a methyl group; 10 is a hydroxyalkyl group having 1 to 4 carbon atoms.

[0048] When the acrylic polymer (A) has a repeating unit (a4) in addition to the repeating unit (a1) represented by formula (I), if the repeating unit (a4) is a repeating unit represented by formula (VI), the affinity between the acrylic polymer (A) and the inorganic powder in the firing slurry can be increased and the intramolecular interaction can be further increased, which makes it easier to form the firing slurry into a sheet and particularly increases the strength of the green sheet.

[0049] Examples of the polymerizable unsaturated monomer that can provide the repeating unit (a4) include at least one monomer selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0050] When the acrylic polymer (A) has the repeating unit (a4), the percentage of the repeating unit (a4) is preferably 20% by mass or more and 60% by mass or less based on the acrylic polymer (A). The percentage of the repeating unit (a4) is more preferably 25% by mass or more, and even more preferably 30% by mass or more. The percentage of the repeating unit (a4) is more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0051] The acrylic polymer (A) may contain only the repeating unit (a1) as a repeating unit constituting a copolymer that can be contained, or may contain the repeating unit (a1) and at least one repeating unit selected from the group consisting of the repeating unit (a2), the repeating unit (a3) ​​and the repeating unit (a4).

[0052] The acrylic polymer (A) may or may not have a repeating unit (hereinafter referred to as repeating unit (a5)) other than the repeating units (a1), (a2), (a3) ​​and (a4). When the acrylic polymer (A) has the repeating unit (a5), the percentage of the repeating unit (a5) is preferably 10% by mass or less based on the acrylic polymer (A).

[0053] Examples of unsaturated ethylenic monomers capable of producing the repeating unit (a5) include benzyl (meth)acrylate, (3-phenoxyphenyl)methyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, glycidyl (meth)acrylate, and allyl (meth)acrylate.

[0054] In addition, the acrylic polymer (A) preferably does not have a repeating unit (a51) which is a residue of a polyfunctional monomer having two or more polymerizable unsaturated groups in one molecule. When the acrylic polymer (A) has the repeating unit (a51), the percentage of the repeating unit (a51) is preferably 5% by mass or less relative to the acrylic polymer (A). In this case, excessive thickening of the binder composition for firing containing the acrylic polymer (A) can be suppressed, and the moldability of the slurry for firing containing the binder composition for firing can be prevented from being deteriorated. In addition, when the acrylic polymer (A) does not have the repeating unit (a51) or the percentage of the repeating unit (a51) is 5% by mass or less relative to the acrylic polymer (A), the combustibility of the binder composition for firing is further improved. This is presumably because a three-dimensional network is less likely to be formed in the skeleton of the acrylic polymer (A), and therefore depolymerization of the acrylic polymer (A) during combustion is less likely to be inhibited.

[0055] The acrylic polymer (A) is synthesized, for example, by a solution polymerization method. For example, a reactive solution is prepared by mixing a polymerizable unsaturated monomer, which is the raw material of the acrylic polymer (A), and a polymerization initiator in a solvent. The polymerizable monomer is a monomer corresponding to each repeating unit contained in the acrylic polymer (A). A chain transfer agent may be further mixed into the reactive solution. The reactive solution is heated and stirred in an inert atmosphere to polymerize the polymerizable monomer, thereby synthesizing the acrylic polymer (A).

[0056] The solvent in the solution polymerization method is not particularly limited as long as it can dissolve or disperse the polymerizable unsaturated monomer and the acrylic polymer (A). The solvent contains at least one selected from the group consisting of, for example, toluene, xylene, ethanol, 2-propanol, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, propylene glycol methyl ether, phenylpropylene glycol, phenyl glycol, texanol, benzyl alcohol, phenyl diglycol, terpineol, dihydroterpineol, dihydroterpinyl acetate, cyclohexanone, cyclopentanone, ethylene glycol, 1,4-butanediol, diethylene glycol, tetraethylene glycol, 1,3-butylene glycol, dipropylene glycol, tripropylene glycol, octanediol, 2,4-diethyl-1,5-pentanediol, diethylene glycol monobutyl ether, butyl carbitol acetate, and solvent naphtha.

[0057] The polymerization initiator contains at least one selected from the group consisting of, for example, azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile); 4-dichlorobenzoyl peroxide, t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butylperoxy-2-ethylhexanoate, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, and di-t-butyl peroxide.

[0058] The chain transfer agent contains at least one 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, 2,3-dimercapto-1-propanol, and α-methylstyrene dimer.

[0059] The weight average molecular weight of the acrylic polymer (A) is, for example, from 50,000 to 200,000. This weight average molecular weight is a relative average weight molecular weight in terms of standard polystyrene measured by gel permeation chromatography.

[0060] (Polyfunctional amine compounds) The polyfunctional amine compound (B) is a compound having at least two amino groups in one molecule. In this embodiment, as described above, the binder composition for firing contains the polyfunctional amine compound (B) together with the acrylic polymer (A), and thus a crosslinking reaction between the acrylic polymer (A) and the polyfunctional amine compound (B) can occur in the green sheet produced from the binder composition. Therefore, in the process of producing a green sheet from the slurry for firing, the carbonyl group of the acetoacetoxy skeleton in the repeating unit (a1) in the acrylic polymer (A) reacts with the amino group in the polyfunctional amine compound (B) to form an imine bond or an enamine bond, thereby forming a crosslinked structure. Therefore, when the binder composition for firing contains the polyfunctional amine compound (B) together with the acrylic copolymer (A) having the repeating unit (a1) represented by the above formula (I), the strength of the green sheet can be further increased by the crosslinked structure. Furthermore, in this embodiment, as described above, even if the acrylic copolymer (A) and the polyfunctional amine compound (B) are mixed in preparing the firing slurry, the storage stability of the slurry is easily maintained.

[0061] The amino group in the polyfunctional amine compound (B) is formed, for example, from a primary amine, a secondary amine, etc. In the present disclosure, the polyfunctional amine compound (B) excludes hydrazine derivatives having an N-N bond in the molecule, that is, hydrazide compounds and hydrazone compounds. In other words, the hydrazide group is distinguished from the amino group.

[0062] An example of the structure formed by the reaction of the acrylic polymer (A) with the polyfunctional amine compound (B) is shown in the following formula (IX).

[0063] [ka]

[0064] In formula (IX), R a are each independently a hydrogen atom or a methyl group, R bare each independently a methylene group, an ethylene group or an ethoxyethylene group, and X is a residue of a polyfunctional amine compound (B).

[0065] Conventionally, it is not preferable to add a crosslinking component to the binder composition for firing, because a resin having a crosslinked structure is likely to leave residues when burned. However, in this embodiment, when the binder composition for firing contains a polyfunctional amine compound (B), as described above, when the amino group of the polyfunctional amine compound (B) reacts with the carbonyl group (at the α-position) of the acetoacetoxy skeleton of the acrylic polymer (A) to form an imine bond or an enamine bond, residues are unlikely to be left. Therefore, in this embodiment, the thermal decomposition property of the binder composition for firing is unlikely to be inhibited by the polyfunctional amine compound (B). In addition, it has been found that the binder composition for firing of this embodiment has the advantage that crosslinking occurs, resulting in good smoothness of the green sheet to be formed.

[0066] In addition, the reaction between the acrylic polymer (A) and the polyfunctional amine compound (B) mainly occurs during the process of drying the sintering slurry to prepare a green sheet. Therefore, when preparing the sintering slurry, gelation and thickening due to the reaction between the acrylic polymer (A) and the polyfunctional amine compound (B) are unlikely to occur, and therefore problems such as deterioration in the handling properties of the sintering binder composition and the sintering slurry during preparation, and deterioration in the formability when preparing a green sheet from the sintering slurry are unlikely to occur. Thus, the sintering binder composition of this embodiment has low reactivity at room temperature, and therefore has excellent storage stability.

[0067] The polyfunctional amine compound (B) preferably contains at least one compound selected from the group consisting of an aliphatic diamine (B1) and a polyether polyamine (B2), which can further improve the strength of the green sheet.

[0068] The aliphatic diamine (B1) preferably contains at least one of ethylenediamine and hexamethylenediamine, which can further improve the strength of the green sheet.

[0069] The polyether polyamine (B2) preferably contains at least one compound selected from a polyether diamine represented by the following formula (VII) and a polyether triamine represented by the following formula (VIII).

[0070] [ka]

[0071] In formula (VII), the value of a+b+c is 2 or more.

[0072] [ka]

[0073] In addition, in formula (VIII), R 11 is a hydrogen atom or an ethyl group, the value of d+e+f is 5 or more and 90 or less, and the value of n is within the range of 0 or more and 1 or less.

[0074] When the polyether polyamine (B2) contains at least one of the compounds represented by the above formula (VII) and formula (VIII), the strength of the green sheet can be further improved. Furthermore, in this case, the stability of the slurry for firing can be further improved when the slurry is prepared. a, b, and c are 0 or a positive number. In addition, d, e, f, and n are 0 or a positive number.

[0075] In formula (VII), it is also preferable that a+b+c≧2, and 0≦a+c≦70, and 0≦b≦60.

[0076] The polyfunctional amine compound (B) may contain a trifunctional or higher amine other than the above formula (VIII), for example, polyethyleneimine, which can also further improve the strength of the green sheet.

[0077] The ratio of amino groups contained in the polyfunctional amine compound (B) is preferably 10 mol% or more and 120 mol% or less relative to the acetoacetoxy groups of the acrylic polymer (A). When the ratio of the polyfunctional amine compound (B) is 10 mol% or more, the strength of the green sheet can be further improved. Furthermore, when this ratio is 120 mol% or less, the thermal decomposition property of the binder composition for firing is less likely to be inhibited. This ratio is more preferably 15 mol% or more, and even more preferably 20 mol% or more. Furthermore, this ratio is more preferably 110 mol% or less, and even more preferably 100 mol% or less.

[0078] [Preparation of binder composition for firing] The binder composition for firing of this embodiment contains the above-mentioned acrylic polymer (A) and polyfunctional amine compound (B). The binder composition for firing may further contain a solvent as necessary. In addition, the binder composition for firing may further contain an additive such as a plasticizer as necessary.

[0079] Although the binder composition for firing is particularly suitable for firing applications, the composition containing the acrylic polymer (A) and the polyfunctional amine compound (B) may be used for applications other than firing. For example, the composition containing the acrylic polymer (A) and the polyfunctional amine compound (B) may be used as an adhesive.

[0080] [Firing slurry] The firing slurry contains a firing binder composition and an inorganic powder. The firing slurry may further contain additives such as a dispersant, if necessary.

[0081] The binder composition for firing may be the binder composition described above. Therefore, the slurry for firing may contain the acrylic polymer (A) and the polyfunctional amine compound (B).

[0082] (Inorganic powder) The inorganic powder may contain an appropriate powder depending on the application of the firing slurry. For example, the inorganic powder may contain one or more materials selected from the group consisting of gold, copper, silver, nickel, palladium, alumina, zirconia, bismuth, titanium oxide, barium titanate, alumina nitride, silicon nitride, boron nitride, silicate glass, lead glass, CaO·Al2O3·SiO2-based inorganic glass, MgO·Al2O3·SiO2-based inorganic glass, and Li2O·Al2O3·SiO2-based inorganic glass.

[0083] The amount of the binder composition for firing and the amount of the inorganic powder in the slurry for firing are preferably appropriately adjusted so as to maintain good application properties of the slurry for firing and good properties of the element obtained by sintering the slurry for firing. For example, the amount of the inorganic powder per 100 parts by mass of the binder composition for firing is 20 parts by mass or more and 4000 parts by mass or less.

[0084] When using the firing slurry, for example, the firing slurry is first formed into a sheet. The firing slurry may be formed, for example, by screen printing, dispensing, or doctor blade, but is not limited thereto. The sheet-shaped firing slurry is then dried by heating. At this time, the conditions for heating the firing slurry for drying are, for example, a heating temperature of 40° C. or more and 200° C. or less, and a heating time of 10 minutes or more and 10 hours or less, depending on the type of solvent. The firing slurry may first be naturally dried at room temperature, and then further dried by heating. This causes the solvent in the firing binder composition to volatilize. In addition, when the firing binder composition contains a polyfunctional amine compound, the reaction between the acrylic polymer (A) and the polyfunctional amine compound proceeds. This causes a green sheet to be produced. In this embodiment, as already described, the green sheet can have high strength.

[0085] By heating this green sheet, the binder composition for firing is thermally decomposed and the inorganic powder is sintered. As a result, a sintered body of the inorganic powder is produced. At this time, the conditions for heating the slurry for firing for sintering are, for example, a heating temperature of 500°C or more and 1500°C or less and a heating time of 1 hour or more and 240 hours or less. In this embodiment, as already described, the binder composition for firing can have good thermal decomposition properties, so that the efficiency of producing the sintered body can be improved and impurities are less likely to remain in the sintered body.

[0086] The method for producing a sintered body using a sintering slurry is particularly suitable for producing a dielectric layer in a multilayer capacitor. However, the use of the sintered body is not limited to a dielectric layer, and the sintered body may constitute an appropriate element such as an electrode, a conductor wiring, or an insulating layer. EXAMPLES

[0087] Specific examples of the present embodiment will be presented below, but the present embodiment is not limited to the following examples.

[0088] (1) Polymer production A 1-liter four-neck flask equipped with a reflux condenser, a thermometer, a nitrogen replacement tube, and a stirrer was used as a reaction vessel. The raw materials other than the polymerization initiator were charged into this reaction vessel in the amounts (parts by mass) shown in Table 1, and the temperature inside the reaction vessel was raised under a nitrogen stream. When the temperature inside the reaction vessel reached 80°C, the polymerization initiator was added, and the polymerization reaction was carried out at 80°C for 6 hours. After the reaction, the reaction vessel was cooled, and a solvent was added so that the solution in the reaction vessel contained 30% by mass of non-volatile matter, thereby obtaining a polymer solution.

[0089] The weight average molecular weight in the polymer solution was measured. The weight average molecular weight is a relative average molecular weight obtained by converting a calibration curve measured by gel permeation chromatography using a standard polymer, and the measurement conditions are as follows: -Apparatus name: Prominence HPLC system (manufactured by Shimadzu Corporation). - Column: KF-805, KF-803, KF-801 (series) (manufactured by Showa Denko K.K.). - Mobile phase: tetrahydrofuran. -Flow rate: 1mL / min. -Detector: Differential refractive index detector. -Temperature: 40℃. -Molecular weight standards: polystyrene.

[0090] The details of the raw materials indicated by the abbreviations in Table 1 are as follows: In Table 1, the monomers corresponding to the repeating unit (a1), repeating unit (a2), repeating unit (a3) ​​and repeating unit (a4) are shown in the columns (a1), (a2), (a3) ​​and (a4), respectively. -AAEM: 2-(methacryloyloxy)ethyl acetoacetate. -MMA: methyl methacrylate. - BMA: n-butyl methacrylate. - EHMA: 2-ethylhexyl methacrylate. -CHMA: cyclohexyl methacrylate. -BA: n-butyl acrylate. -MAA: methacrylic acid. -CCLA: ω-Carboxypolycaprolactone acrylate -MOES: 2-methacryloyloxyethyl succinate. -AOES: 2-acryloyloxyethyl succinate. -HEMA: 2-hydroxyethyl methacrylate. -PGM: Propylene glycol methyl ether. -MSD: α-methylstyrene dimer. -AIBN: 2,2'-azobisisobutyronitrile.

[0091] [Table 1]

[0092] (2) Preparation of green sheet The raw materials shown in Tables 2 and 3 were mixed in the mass% amounts and stirred for 10 minutes using a stirring and defoaming device to prepare a sintering slurry. This sintering slurry was applied onto a polyethylene terephthalate film, naturally dried at room temperature for 12 hours, and then heated for 60 minutes at a temperature in the range of 100°C to 150°C depending on the type of solvent. In this way, a green sheet with a thickness of 200 μm for evaluation was produced.

[0093] Details of the raw materials shown by abbreviations in Tables 2 and 3 are as follows: -BT-01: Barium titanate, manufactured by Sakai Chemical Industry Co., Ltd. -PGM: Propylene glycol methyl ether. -BYK-102: Anionic polymerization initiator, manufactured by BYK-Chemie, product number BYK-102. -PEG400: Polyethylene glycol #400. -DOA: bis(2-ethylhexyl) adipate. -HT-510: Polyethylene glycol-polypropylene glycol alkyl ether. NOF Corporation, product number HT-510. -PVB: Polyvinyl butyral. Sekisui Chemical Co., Ltd., product name: S-LEC BH-3. - D-230: Jeffamine (registered trademark) product name manufactured by HUNTSMAN, product number D-230. (Polyoxypropylenediamine represented by formula (VII). In formula (VII), the value of a+b+c is about 2.5 or less. Mw (weight average molecular weight) 230.) -D-2000: Product name Jeffamine (registered trademark) manufactured by HUNTSMAN, product number D-2000. (Polyoxypropylenediamine represented by formula (VII). In formula (VII), the value of a+b+c is about 33 or less. Mw (weight average molecular weight) 2000.) -T-403: Jeffamine (registered trademark) product number T-403 manufactured by HUNTSMAN. (Trimethylolpropane poly(oxypropylene) triamine represented by formula (VIII). In formula (VIII), R 11 =C2H5, n=1, d+e+f value is 5-6. Mw (weight average molecular weight) 440.

[0094] (3) Evaluation (3-1) Tensile strength A sample with dimensions of 1 cm width and 6 cm length was cut out from the prepared green sheet. The tensile strength (maximum stress) of the sample (unit: kgf / cm) was measured using a tensile testing machine (Shimadzu Corporation, model number AGS-1kNX). 2 ) was measured at a tensile speed of 20 mm / min. The measured values ​​are shown in Tables 2 and 3.

[0095] (3-2) Thickening of slurry The raw materials shown in Tables 2 and 3 were mixed and stirred for 10 minutes using a stirring and defoaming device to prepare a ceramic slurry. The resulting ceramic slurry was stored in a sealed container at a constant temperature of 25°C, and the viscosity of the slurry was confirmed. The viscosity of the slurry was evaluated according to the following criteria. A: After the slurry was prepared, it did not gel even after being stored for one day (24 hours). B: The slurry was observed to gel between 3 hours and 24 hours after preparation. C: The slurry gelled within 1 hour or more and less than 3 hours after preparation. D: The slurry gelled within 1 hour after preparation.

[0096] In addition, in Comparative Examples 1 to 5, since there was no crosslinked structure based on the repeating unit (a1) and thickening could not be confirmed, the results are indicated by "-".

[0097] (3-3) Sinterability The polymer solution used to prepare the green sheet was dried to volatilize the solvent, and the obtained sample was measured using a simultaneous differential thermal and thermogravimetric analyzer (TG-DTA8122, Rigaku Corporation) in an air atmosphere at a heating rate of 10°C / min over a temperature range of 25°C to 500°C.

[0098] As a result, the weight loss rate of the sample at 500°C, based on the weight of the sample at 25°C, was evaluated as "A" if it was 99% or more, "B" if it was 95% or more but less than 99%, and "C" if it was less than 95%.

[0099] The results are shown in Tables 2 and 3.

[0100] [Table 2]

[0101] [Table 3]

[0102] As shown by the above results, in Examples 1 to 16, the binder composition for firing contained the acrylic polymer (A) having the repeating unit (a1) represented by formula (I) and the polyfunctional amine compound (B), and therefore it was found that the green sheet produced from this binder composition for firing had excellent strength and that the binder composition for firing had excellent firing properties.

[0103] On the other hand, in Comparative Examples 2 to 4, the sintering binder compositions contained a polymer that did not have the repeating unit (a1) represented by formula (I), and therefore the sintering properties of the polymer were excellent, but the strength of the green sheet was inferior to that of any of the Examples.

[0104] In addition, in Comparative Example 5, since polyvinyl butyral was contained as a binder, the strength of the green sheet was excellent, but the sinterability was low, and it was found that the conditions for use as a sintering binder were limited.

[0105] 3. Summary As is apparent from the above embodiments and examples, the present disclosure includes the following aspects.

[0106] The binder composition for firing according to the first embodiment contains an acrylic polymer (A) and a polyfunctional amine compound (B). The acrylic polymer (A) has a repeating unit (a1) represented by the following formula (I): In formula (I), R1 is a hydrogen atom or a methyl group, and R2 is a methylene group, an ethylene group, or an ethoxyethylene group.

[0107] [ka]

[0108] According to this embodiment, the stability of the prepared slurry can be ensured, and the strength of the green sheet produced from the sintering slurry containing the sintering binder composition can be increased without impairing the thermal decomposition property.

[0109] In the binder composition for firing of the second embodiment, in the first embodiment, the acrylic polymer (A) further has a repeating unit (a2) represented by the following formula (II): In formula (II), R3 is a hydrogen atom or a methyl group, and R4 is a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms.

[0110] [ka]

[0111] According to this embodiment, the binder may have better properties such as moldability and thermal decomposition property.

[0112] In the binder composition for firing of the third embodiment, in the first or second embodiment, the acrylic polymer (A) further has a repeating unit (a3) ​​which is a residue of a polymerizable unsaturated monomer containing a carboxyl group.

[0113] According to this embodiment, the affinity between the acrylic polymer (A) and the inorganic powder in the sintering slurry can be increased, which makes it easier to form the sintering slurry into a sheet and further increases the strength of the green sheet.

[0114] In the binder composition for firing of the fourth aspect, in the third aspect, the repeating unit (a3) ​​is a repeating unit represented by the following formula (III). In formula (III), R5 is a hydrogen atom or a methyl group, and R6 is a hydrogen atom or a substituent represented by the following formula (IV) or formula (V). In formula (IV), R7 is a methylene group or an ethylene group, and R8 is a methylene group or an ethylene group. In formula (V), the value of n is within the range of 1 or more and 10 or less.

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] According to this embodiment, the affinity between the acrylic polymer (A) and the inorganic powder in the sintering slurry can be further increased, which makes it easier to form the sintering slurry into a sheet and particularly increases the strength of the green sheet.

[0119] A fifth aspect of the binder composition for firing is any one of the first to fourth aspects, in which the acrylic polymer (A) further has a repeating unit (a4) which is a residue of a polymerizable unsaturated monomer containing a hydroxyl group.

[0120] According to this embodiment, the affinity between the acrylic polymer (A) and the inorganic powder in the sintering slurry can be increased, and the intramolecular interaction can be increased. As a result, the sintering slurry can be easily formed into a sheet, and the strength of the green sheet can be further increased.

[0121] In the binder composition for firing of the sixth aspect, in the fifth aspect, the repeating unit (a4) is a repeating unit represented by the following formula (VI): In formula (VI), R9 is a hydrogen atom or a methyl group, and R 10 is a hydroxyalkyl group having 1 to 4 carbon atoms.

[0122] [ka]

[0123] According to this embodiment, the affinity between the acrylic polymer (A) and the inorganic powder in the firing slurry can be increased, and the intramolecular interaction can be further enhanced, which makes it easier to form the firing slurry into a sheet, and particularly increases the strength of the green sheet.

[0124] A seventh aspect of the binder composition for firing is any one of the first to sixth aspects, in which the content of the repeating unit (a1) in the acrylic polymer (A) is 2% by mass or more and 20% by mass or less.

[0125] According to this embodiment, when the percentage of the repeating unit (a1) is 2% by mass or more, the hardness of the green sheet can be increased, and when this percentage is 20% by mass or less, the green sheet can have appropriate flexibility.

[0126] The binder composition for firing of the eighth aspect is any one of the first to seventh aspects, in which the polyfunctional amine compound (B) contains at least one compound of an aliphatic diamine (B1) and a polyether polyamine (B2).

[0127] According to this embodiment, the strength of the green sheet can be further improved.

[0128] A ninth aspect of the binder composition for firing is the eighth aspect, in which the aliphatic diamine (B1) contains at least one diamine of ethylenediamine and hexamethylenediamine.

[0129] According to this embodiment, the strength of the green sheet can be further improved.

[0130] The binder composition for firing according to the tenth aspect is the binder composition according to the eighth or ninth aspect, in which the polyether polyamine (B2) contains at least one compound selected from the group consisting of a polyether diamine represented by the following formula (VII) and a polyether triamine represented by the following formula (VIII). In formula (VII), the value of a+b+c is 2 or more. In formula (VIII), R 11 is a hydrogen atom or an ethyl group, the value of d+e+f is 5 or more and 90 or less, and the value of n is within the range of 0 or more and 1 or less.

[0131] [ka]

[0132] [ka]

[0133] According to this embodiment, the green sheet can have a more appropriate flexibility, and therefore the strength of the green sheet can be further improved. Furthermore, in this case, the stability of the firing slurry when it is prepared can be further improved.

[0134] A slurry for firing according to an eleventh embodiment contains the binder composition for firing according to any one of the first to tenth embodiments and an inorganic powder.

[0135] According to this embodiment, the stability of the prepared slurry can be ensured, and the strength of the produced green sheet can be increased without impairing the thermal decomposition property.

Claims

1. Contains an acrylic polymer (A) and a polyfunctional amine compound (B), The acrylic polymer (A) has a repeating unit (a1) represented by the following formula (I), 【Chemistry 1】 In the formula (I), R １ is a hydrogen atom or a methyl group, R ２ is a methylene group, an ethylene group, or an ethoxyethylene group; A binder composition for firing.

2. The acrylic polymer (A) further has a repeating unit (a2) represented by the following formula (II): 【Chemistry 2】 In the formula (II), R ３ is a hydrogen atom or a methyl group, R ４ is a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms; The sintering binder composition according to claim 1 .

3. The acrylic polymer (A) further has a repeating unit (a3) ​​which is a residue of a polymerizable unsaturated monomer containing a carboxyl group. The binder composition for firing according to claim 1 or 2.

4. The repeating unit (a3) ​​is a repeating unit represented by the following formula (III): 【Chemistry 3】 In the formula (III), R ５ is a hydrogen atom or a methyl group, R ６ is a hydrogen atom or a substituent represented by the following formula (IV) or formula (V), 【Chemistry 4】 【Chemistry 5】 In the formula (IV), R ７ is a methylene group or an ethylene group, R ８ is a methylene group or an ethylene group, and in formula (V), the value of n is within the range of 1 to 10. The binder composition for firing according to claim 3 .

5. The acrylic polymer (A) further has a repeating unit (a4) which is a residue of a polymerizable unsaturated monomer containing a hydroxyl group. The binder composition for firing according to claim 1 or 2.

6. The repeating unit (a4) is a repeating unit represented by the following formula (VI): 【Chemistry 6】 In the formula (VI), R ９ is a hydrogen atom or a methyl group, R １０ is a hydroxyalkyl group having 1 to 4 carbon atoms; The binder composition for firing according to claim 5 .

7. The content of the repeating unit (a1) in the acrylic polymer (A) is 2% by mass or more and 20% by mass or less. The binder composition for firing according to claim 1 or 2.

8. The polyfunctional amine compound (B) contains at least one compound selected from the group consisting of an aliphatic diamine (B1) and a polyether polyamine (B2). The binder composition for firing according to claim 1 or 2.

9. The aliphatic diamine (B1) contains at least one diamine selected from the group consisting of ethylenediamine and hexamethylenediamine. The binder composition for firing according to claim 8.

10. The polyether polyamine (B2) contains at least one compound selected from a polyether diamine represented by the following formula (VII) and a polyether triamine represented by the following formula (VIII), 【Chemistry 7】 In the formula (VII), the value of a+b+c is 2 or more; 【Chemistry 8】 In the formula (VIII), R 11 is a hydrogen atom or an ethyl group, the value of d+e+f is 5 or more and 90 or less, and the value of n is within the range of 0 or more and 1 or less; The binder composition for firing according to claim 8.

11. A binder composition for firing according to claim 1 or 2, and an inorganic powder are contained therein. Slurry for firing.

Images