Binder for firing, composition for firing, and method for producing sintered body

Abstract

Provided is a binder for firing containing an aliphatic polycarbonate, wherein the aliphatic polycarbonate has, in a side chain, a substituted or unsubstituted hydrocarbon group having 2 carbon atoms and directly bonded to the main chain, and the mass-average molecular weight (Mw) of the aliphatic polycarbonate is 200,000 or more.

Description

Binder for firing, composition for firing, method for manufacturing sintered body

[0001] The present invention relates to a binder for firing, a composition for firing, and a method for producing a sintered body.

[0002] Sintered bodies, which are formed by sintering inorganic particles such as metal particles and ceramic particles, have been conventionally used in various fields such as electronic materials and structural materials. One method for manufacturing sintered bodies involves molding a firing composition, which is a mixture of inorganic powder and a firing binder, into a desired shape, and then firing the firing composition to sinter the inorganic powder.

[0003] The firing binder is a resin material that plays a role in enhancing the shape retention, flexibility, and other properties of the firing composition. By including this firing binder, the degree of freedom in the shape design and usage method of the firing composition can be increased, for example, by molding the firing composition into a film for use.

[0004] Patent Document 1 discloses a binder composition for low-temperature firing, comprising 100 parts by weight of a (meth)acrylate polymer (A) having a functional group capable of hydrogen bonding with a hydroxyl group, 20 to 200 parts by weight of an organic compound (B) having three or more hydroxyl groups, and 100 parts by weight or less of an organic solvent with a boiling point of 150°C or higher.

[0005] Patent Document 2 discloses a sintering bonding composition containing conductive metal-containing sinterable particles having an average particle size of 70 nm or more and 2 μm or less, with a proportion of particles with a particle size of 100 nm or less being 80% by mass or more, wherein polypropylene carbonate is used as the firing binder.

[0006] Japanese Patent Publication No. 2006-160791 Japanese Patent Publication No. 2023-41064

[0007] A calcination composition containing a calcination binder needs to be calcined at a relatively high temperature in order to sufficiently thermally decompose the calcination binder during calcination. However, from a productivity standpoint, it is desirable that it be calcined at the lowest possible temperature. Therefore, excellent thermal decomposition properties are required for calcination binders to enable low-temperature calcination.

[0008] Furthermore, a problem in handling the firing composition is that cracks occur when the firing composition is deformed, making it difficult to manufacture the desired sintered body. According to the inventors' studies, it has been found that cracks are more likely to occur in the firing composition when the Young's modulus of the firing binder is high. However, if the Young's modulus of the firing binder is sufficiently low, the tensile strength decreases, resulting in a problem of low mechanical strength of the firing composition. Therefore, the firing binder is required to have excellent thermal decomposition properties, a low Young's modulus, and good tensile strength. However, the acrylate polymer described in Patent Document 1 and the polypropylene carbonate described in Patent Document 2 did not satisfy these requirements.

[0009] This invention has been made in view of the above circumstances, and aims to provide a firing binder that has a low Young's modulus, good fracture strength, and excellent thermal decomposition properties, a firing composition using the firing binder, and a method for manufacturing a sintered body using the firing composition.

[0010] As a result of diligent research, the inventors have discovered that the above problems can be solved by a calcination binder having a specific chemical structure and molecular weight, and have completed the present invention described below.

[0011] In other words, the present invention relates to the following [1] to

[10] . [1] A firing binder containing an aliphatic polycarbonate, wherein the aliphatic polycarbonate has substituted or unsubstituted carbon-2 hydrocarbon groups in its side chains that are directly bonded to the main chain, and the mass-average molecular weight (Mw) of the aliphatic polycarbonate is 200,000 or more. [2] The firing binder according to [1], wherein the aliphatic polycarbonate has a structural unit represented by the following general formula (1a). (In the formula, R １ , R ２ , R ３ and R ４ Each is independently a hydrogen atom or a substituted or unsubstituted 2-carbon hydrocarbon group, R １ , R ２ , R ３and R ４ , at least one is the substituted or unsubstituted C2 hydrocarbon group.) [3] R in the general formula (1a) １ , R ２ , R ３ and R ４ only one of which is the substituted or unsubstituted C2 hydrocarbon group, the binder for firing according to [2] above. [4] The binder for firing according to any one of [1] to [3] above, wherein the substituted or unsubstituted C2 hydrocarbon group is an unsubstituted C2 hydrocarbon group. [5] The binder for firing according to any one of [1] to [4] above, wherein the aliphatic polycarbonate contains no ether bond, or the aliphatic polycarbonate contains an ether bond, and the content of the ether bond is 20 mol% or less based on the total amount (100 mol%) of carbonate bonds and ether bonds. [6] A firing composition comprising the binder for firing according to any one of [1] to [5] above, and one or more sintering particles selected from the group consisting of metal oxide precursor particles and metal oxide particles. [7] The firing composition according to [6] above, which is in the form of a paste. [8] The firing composition according to [6] above, which is in the form of a film. [9] A method for producing a sintered body, comprising heating the firing composition according to any one of [6] to [8] above.

[10] The method for producing a sintered body according to [9] above, wherein the firing composition is heated in an atmosphere having an oxygen partial pressure of 5.0 kPa or less.

[0012] According to the present invention, there can be provided a binder for firing that has a low Young's modulus, good breaking strength, and excellent thermal decomposability, a firing composition using the binder for firing, and a method for producing a sintered body using the firing composition.

[0013] In this specification, with respect to preferable numerical ranges, the lower limits and upper limits described stepwise can be combined independently of each other. For example, from the description "preferably 10 to 90, more preferably 30 to 60", the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to obtain "10 to 60".

[0014] As used herein, the "thickness" of an object refers to the total thickness of the entire object. For example, when the object is composed of a plurality of layers, the "thickness" means the total thickness of all layers constituting the object. Unless otherwise specified, the "thickness" of an object as used herein refers to the average value of thicknesses measured at five randomly selected locations on the object, and can be obtained using a constant-pressure thickness measuring instrument in accordance with JIS K 7130:1999.

[0015] As used herein, the term "solid content" refers to components excluding solvents among the components contained in the target composition.

[0016] As used herein, the term "paste" means a mixture in which part or all of the solid content is dispersed in a solvent.

[0017] The mechanism of action described herein is a conjecture, and does not limit the mechanism by which the effects of the present invention are achieved.

[0018] [Binder for Firing] The binder for firing according to the present embodiment is a binder for firing containing an aliphatic polycarbonate, wherein the aliphatic polycarbonate has, as a side chain, a substituted or unsubstituted 2-carbon hydrocarbon group directly bonded to the main chain, and the mass average molecular weight (Mw) of the aliphatic polycarbonate is 200,000 or more.

[0019] In the following description, the aliphatic polycarbonate contained in the binder for firing of the present embodiment may be referred to as "aliphatic polycarbonate (A)".

[0020] The binder for firing according to the present embodiment has a low Young's modulus, good breaking strength, and excellent thermal decomposability. Although the details of the reason therefor are unclear, it is speculated as follows. The aliphatic polycarbonate (A) contained in the binder for firing according to the present embodiment has a carbonate structure, and thus exhibits excellent thermal decomposability through a specific reaction, specifically a backbiting reaction. Therefore, the binder for firing according to the present embodiment can be fired at a relatively low temperature. Further, since the aliphatic polycarbonate (A) has, in a side chain thereof, a substituted or unsubstituted 2-carbon hydrocarbon group that directly bonds to the main chain, the interaction between molecular chains is reduced, so it is considered that the aliphatic polycarbonate (A) has a low Young's modulus. Furthermore, since the aliphatic polycarbonate (A) has a mass average molecular weight (Mw) of 200,000 or more, entanglement between molecular chains is likely to occur, so it is speculated that the aliphatic polycarbonate (A) has good breaking strength.

[0021] <Aliphatic Polycarbonate (A)> The binder for firing according to the present embodiment contains the aliphatic polycarbonate (A). One type of the aliphatic polycarbonate (A) may be used alone, or two or more types may be used in combination.

[0022] The aliphatic polycarbonate (A) has, in a side chain thereof, a substituted or unsubstituted 2-carbon hydrocarbon group that directly bonds to the main chain. In the present embodiment, the side chain of the aliphatic polycarbonate (A) refers to an atomic group containing a carbon atom branched from a carbon atom chain linearly connected to adjacent carbonate groups, among molecular chains formed by linking structural units each composed of a divalent aliphatic hydrocarbon group and a carbonate group (-O-C(=O)-O-) (hereinafter also referred to as "carbonate units"). In addition, the main chain of the aliphatic polycarbonate (A) refers to a molecular chain excluding side chains, among the molecular chains formed by linking said carbonate units. For example, in a case where carbonate units each composed of a branched divalent aliphatic hydrocarbon group and a carbonate group (-O-C(=O)-O-) are linked, the carbon atom chain linearly connected to the carbonate groups is the carbon atom chain constituting the main chain, and among the branched divalent aliphatic hydrocarbon group, the carbon atom chain branched from said linearly connected carbon atom chain is the carbon atom chain constituting the side chain.

[0023] In the following explanation, the "substituted or unsubstituted C2 hydrocarbon group" in the side chain of aliphatic polycarbonate (A) may be referred to as "hydrocarbon group (X)".

[0024] The hydrocarbon group (X) has two carbon atoms, and this number of carbon atoms in the hydrocarbon group (X) results in the aliphatic polycarbonate (A) having a low Young's modulus, good tensile strength, and excellent thermal decomposition properties. Note that the carbon number of substituents is not included in the carbon number of the hydrocarbon group (X) mentioned above.

[0025] Examples of substituents that the hydrocarbon group (X) may have include hydroxyl groups, thiol groups, cyano groups, amino groups, silyl groups, halogen atoms such as fluorine, chlorine, bromine, and iodine; alkoxy groups, alkenyloxy groups; aryl groups such as phenyl groups; heteroaryl groups containing oxygen, nitrogen, sulfur, selenium, and phosphorus atoms as heteroatoms; aryloxy groups such as phenoxy groups; heteroaryloxy groups containing oxygen, nitrogen, sulfur, selenium, and phosphorus atoms as heteroatoms; alkylsilyl groups; alkylsilyloxy groups; and so on. From the viewpoint of thermal decomposition, the number of carbon atoms in the substituents that the hydrocarbon group (X) may have is preferably 6 or less, more preferably 3 or less, even more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0. From the viewpoint of thermal decomposition, it is preferable that the hydrocarbon group (X) does not have substituents containing hydrocarbon groups, and it is more preferable that it does not have substituents.

[0026] The hydrocarbon group (X) is preferably a substituted or unsubstituted ethyl group, and more preferably an unsubstituted ethyl group.

[0027] The main chain of aliphatic polycarbonate (A) may or may not have groups other than hydrocarbon groups (X) as side chains or substituents. From the viewpoint of thermal decomposition, it is preferable that the groups other than hydrocarbon groups (X) do not contain hydrocarbon groups having 2 or more carbon atoms. Examples of groups that do not contain hydrocarbon groups having 2 or more carbon atoms include substituted or unsubstituted methyl groups; substituted or unsubstituted methoxy groups; hydroxyl groups; thiol groups; cyano groups; amino groups; silyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; and so on. However, from the viewpoint of thermal decomposition, it is preferable that aliphatic polycarbonate (A) does not have groups other than hydrocarbon groups (X) directly bonded to the main chain.

[0028] From the viewpoint of low Young's modulus and thermal decomposition properties, the structural unit having a hydrocarbon group (X) in its side chain is preferably a structural unit represented by the following general formula (1).

[0029] (In the formula, R １ and R ２ Each of these is a group that does not contain a hydrogen atom, a hydrocarbon group (X), or a hydrocarbon group having 2 or more carbon atoms, and all R contained in the structural unit １ and R ２ At least one of these is a hydrocarbon group (X). n is an integer between 1 and 10.

[0030] R １ and R ２ The explanations for the "hydrocarbon group (X)" and "groups that do not contain hydrocarbon groups with two or more carbon atoms" are as described above.

[0031] All R included in the structural unit represented by the general formula (1) above １ and R ２ Of these, at least one is a hydrocarbon group (X), and from the viewpoint of thermal decomposition, it is preferable that one to three are hydrocarbon groups (X), more preferably that one or two are hydrocarbon groups (X), and even more preferably that only one is a hydrocarbon group (X).

[0032] All R included in the structural unit represented by the general formula (1) above １ and R ２Of these, it is preferable that all those that are not hydrocarbon groups (X) are hydrogen atoms.

[0033] In the above general formula (1), n ​​is an integer from 1 to 10, and from the viewpoint of low Young's modulus and thermal decomposition, it is preferably 1 to 8, more preferably 2 to 6, even more preferably 2 to 4, even more preferably 2 to 3, and particularly preferably 2.

[0034] The structural unit represented by the above general formula (1) in the aliphatic polycarbonate (A) may be a single type or two or more types.

[0035] From the viewpoint of low Young's modulus and thermal decomposition properties, the structural unit represented by the above general formula (1) is preferably the structural unit represented by the following general formula (1a).

[0036] (In the formula, R １ , R ２ , R ３ and R ４ Each is independently a hydrogen atom or a hydrocarbon group (X), and R １ , R ２ , R ３ and R ４ At least one of these is a hydrocarbon group (X).

[0037] From the viewpoint of low Young's modulus and thermal decomposition properties, the structural unit represented by the above general formula (1a) is preferably the structural unit represented by the following formula (1a-1) or the structural unit represented by the following formula (1a-2).

[0038]

[0039] Aliphatic polycarbonate (A) may or may not contain structural units other than carbonate units having a hydrocarbon group (X) in their side chains. From the viewpoint of low Young's modulus and thermal decomposition properties, the content of carbonate units having a hydrocarbon group (X) in their side chains, structural units represented by the above general formula (1), or structural units represented by the above general formula (1a) in aliphatic polycarbonate (A) is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more, and may be 100 mol%. Note that "total structural units" of aliphatic polycarbonate (A) means the total number of structural units based on one monomer molecule. Structures derived from carbon dioxide are not counted as a single unit; rather, a structure formed from one monomer molecule and one carbon dioxide molecule (i.e., a structure consisting of a divalent hydrocarbon group and a carbonate group (-O-C(=O)-O-) derived from one monomer molecule) is considered a single unit.

[0040] As the aliphatic polycarbonate (A), polybutylene carbonate is preferred from the viewpoint of low Young's modulus and thermal decomposition properties.

[0041] (Ether bond content of aliphatic polycarbonate (A)) From the viewpoint of improving thermal decomposition properties, aliphatic polycarbonate (A) preferably contains no ether bonds or contains ether bonds, and the content of said ether bonds (hereinafter also simply referred to as "ether ratio") is 20 mol% or less relative to the total amount of carbonate bonds and ether bonds (100 mol%). From a similar viewpoint, the ether bond content in aliphatic polycarbonate (A) is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 7 mol% or less, relative to the total amount of carbonate bonds and ether bonds (100 mol%). The ether bond content in aliphatic polycarbonate (A) may be 0 mol%, or it may be 1 mol% or more. Note that the -O- bond in the carbonate bond (-O-C(=O)-O-) does not fall under the category of ether bond. The ether bond content in aliphatic polycarbonate (A) can be measured by the method described in the examples.

[0042] (99% thermal decomposition temperature of aliphatic polycarbonate (A)) The 99% thermal decomposition temperature of aliphatic polycarbonate (A) in a nitrogen atmosphere with an oxygen partial pressure of 0.1 kPa or less is preferably 400°C or less, more preferably 380°C or less, even more preferably 350°C or less, and even more preferably 320°C or less. If the 99% thermal decomposition temperature of aliphatic polycarbonate (A) in a nitrogen atmosphere with an oxygen partial pressure of 0.1 kPa or less is below the above upper limit, excellent thermal decomposition properties can be easily obtained in an inert atmosphere. The lower limit of the 99% thermal decomposition temperature of aliphatic polycarbonate (A) in a nitrogen atmosphere with an oxygen partial pressure of 0.1 kPa or less is not particularly limited, but from the viewpoint of suppressing the decomposition of aliphatic polycarbonate (A) in the drying process to remove the solvent from the calcination composition, it may be 170°C or higher, 200°C or higher, or 230°C or higher. Furthermore, the 99% pyrolysis temperature in a nitrogen atmosphere with an oxygen partial pressure of 0.1 kPa or less shall be measured by thermogravimetric analysis (TGA) under atmospheric pressure, and specifically, it can be measured by the method described in the examples.

[0043] (Glass transition temperature (Tg) of aliphatic polycarbonate (A)) The glass transition temperature (Tg) of aliphatic polycarbonate (A) is preferably -40 to +25°C, more preferably -30 to +20°C, even more preferably -20 to +15°C, even more preferably -10 to +10°C, and particularly preferably -7 to +7°C, from the viewpoint of easily obtaining a low Young's modulus and high breaking strength. The glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC), and specifically can be measured by the method described in the examples.

[0044] (Mass-average molecular weight (Mw) of aliphatic polycarbonate (A)) The mass-average molecular weight (Mw) of aliphatic polycarbonate (A) is 200,000 or more from the viewpoint of obtaining good tensile strength. From a similar viewpoint, the mass-average molecular weight (Mw) of aliphatic polycarbonate (A) is preferably 250,000 or more, more preferably 300,000 or more, even more preferably 350,000 or more, and even more preferably 400,000 or more. Furthermore, from the viewpoint of the flexibility of the binder for firing, the mass-average molecular weight (Mw) of aliphatic polycarbonate (A) is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 600,000 or less. The mass-average molecular weight (Mw) refers to the value on a standard polystyrene basis measured by gel permeation chromatography (GPC), and can be measured by the method described in the examples.

[0045] (Young's modulus of aliphatic polycarbonate (A) at 23°C) The Young's modulus of aliphatic polycarbonate (A) at 23°C is preferably 40 MPa or less, more preferably 30 MPa or less, even more preferably 20 MPa or less, even more preferably 10 MPa or less, and particularly preferably 7 MPa or less, from the viewpoint of increasing the flexibility of the firing composition. The Young's modulus of aliphatic polycarbonate (A) at 23°C may be 0.1 MPa or more, 0.2 MPa or more, or 0.3 MPa or more, from the viewpoint of ease of manufacture. The Young's modulus of aliphatic polycarbonate (A) at 23°C can be measured by the method described in the examples.

[0046] (Breaking strength of aliphatic polycarbonate (A) at 23°C) The breaking strength of aliphatic polycarbonate (A) at 23°C is preferably 0.2 MPa or higher, more preferably 0.5 MPa or higher, from the viewpoint of increasing the mechanical strength of the firing composition. The breaking strength of aliphatic polycarbonate (A) at 23°C may be 100 MPa or less, 50 MPa or less, or 10 MPa or less, from the viewpoint of ease of manufacture. The breaking strength of aliphatic polycarbonate (A) at 23°C can be measured by the method described in the examples.

[0047] (Ratio of Young's modulus at 23°C to fracture strength at 23°C for aliphatic polycarbonate (A)) The ratio of Young's modulus at 23°C to fracture strength at 23°C [Young's modulus / fracture strength] of aliphatic polycarbonate (A) is preferably 9.0 or less, more preferably 7.0 or less, and even more preferably 5.0 or less, from the viewpoint of reducing the brittleness of the firing composition. The ratio of Young's modulus at 23°C to fracture strength at 23°C [Young's modulus / fracture strength] of aliphatic polycarbonate (A) may be 0.1 or more from the viewpoint of ease of manufacture. The above ratio [Young's modulus / fracture strength] can be measured by the method described in the examples.

[0048] (Method for producing aliphatic polycarbonate (A)) The method for producing aliphatic polycarbonate (A) is not particularly limited, but for example, carbon dioxide (CO2) ２ It can be produced by polymerizing a monomer that forms a divalent aliphatic hydrocarbon group constituting the main chain (hereinafter simply referred to as "raw material monomer"). The conditions for the above polymerization reaction can be, for example, those described in International Publication No. 2011 / 142259.

[0049] Examples of raw material monomers include 1,2-butylene oxide and derivatives of 1,2-butylene oxide. One raw material monomer may be used alone, or two or more may be used in combination.

[0050] The above polymerization reaction is preferably carried out in the presence of a metal catalyst. Examples of metal catalysts include metal salen complex catalysts, complex metal cyanide complex catalysts (DMC catalysts), and organometallic catalysts. Among these, DMC catalysts and organozinc catalysts are preferred from the viewpoint of exhibiting high polymerization activity and being easy to adjust the mass-average molecular weight (Mw) to 200,000 or more, with Zn being a preferred DMC catalyst. ３ (Co[CN] ６ ) ２ More preferably, aliphatic dicarboxylate zinc is preferred as the organozinc catalyst. One metal catalyst may be used alone, or two or more may be used in combination. The amount of metal catalyst used is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 3 parts by mass, per 100 parts by mass of raw material monomer for the DMC catalyst. For the organozinc catalyst, it is preferably 0.1 to 40 parts by mass, more preferably 1.0 to 20 parts by mass, per 100 parts by mass of raw material monomer.

[0051] The polymerization reaction described above may also use a co-catalyst in addition to the metal catalyst. Examples of co-catalysts include bis(triphenylphosphoranylidene)ammonium chloride, 4-dimethylaminopyridine, tetrabutylammonium chloride, tetrabutylammonium bromide, triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]deca-5-ene, and 1,4-diazabicyclo[2.2.2]octane. One co-catalyst may be used alone, or two or more may be used in combination. The amount of co-catalyst used is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 14 parts by mass, per 100 parts by mass of the raw material monomer.

[0052] The method for carrying out the polymerization reaction is not particularly limited as long as the target product is obtained, but for example, one method involves charging a starting monomer, a metal catalyst, a co-catalyst, and a solvent to be used as needed into an autoclave, mixing them, and then injecting carbon dioxide into the resulting mixture to carry out the reaction. The solvent used as needed in the polymerization reaction is not particularly limited, but an organic solvent is preferred. The amount of solvent used is preferably 10 to 10,000 parts by mass per 100 parts by mass of monomer used.

[0053] The pressure at which carbon dioxide is injected during the polymerization reaction is preferably 0.1 to 20 MPa, more preferably 0.1 to 10 MPa, and even more preferably 0.1 to 5 MPa. If the pressure at which carbon dioxide is injected is above the lower limit, the polymerization reaction proceeds more easily. Also, if the pressure at which carbon dioxide is injected is below the upper limit, excessive use of carbon dioxide is suppressed, improving economic efficiency.

[0054] The reaction temperature during the polymerization reaction is preferably 20 to 100°C, more preferably 25 to 80°C, from the viewpoint of reaction rate and suppression of side reactions. The reaction time for the polymerization reaction can be adjusted as appropriate according to the reaction temperature, but is preferably 2 to 40 hours.

[0055] During the polymerization reaction, it is preferable to keep the amount of water in the reaction system at 3 mol% or less relative to the amount (moles) of metal catalyst used.

[0056] After the polymerization reaction is complete, the target aliphatic polycarbonate (A) can be isolated by known methods after performing any known post-treatment procedures. The obtained aliphatic polycarbonate (A) may also be purified if necessary.

[0057] (Content of aliphatic polycarbonate (A)) The content of aliphatic polycarbonate (A) in the firing binder of this embodiment is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, and even more preferably 99 to 100% by mass, and may be 100% by mass.

[0058] <Other Optional Components> The firing binder of this embodiment may contain other optional components besides aliphatic polycarbonate (A). Examples of other optional components include resins other than aliphatic polycarbonate (A), dispersants, plasticizers, tackifiers, preservatives, defoamers, thermal decomposition accelerators, antioxidants, etc. Each of these may be used individually or in combination of two or more. These additives can be appropriately selected from those commonly used in this field. The content of the above optional components in the firing binder of this embodiment is not particularly limited and may be used as needed, within a range that does not hinder the effects of this embodiment. Furthermore, the firing binder of this embodiment may not contain the above optional components, depending on the desired performance.

[0059] <Uses of the firing binder> The firing binder of this embodiment is suitable as a binder for firing compositions containing sintering particles such as metals and ceramics, and is more suitable as a binder for firing compositions containing one or more sintering particles selected from the group consisting of metal oxide precursor particles and metal oxide particles, as described later.

[0060] A sintered body produced from a firing composition to which the firing binder of this embodiment is applied (hereinafter also referred to as "the sintered body of this embodiment") may be an article composed solely of the sintered body of this embodiment, or it may constitute a composite of the sintered body of this embodiment and other components (hereinafter also referred to as "other components"). The composite has a structure in which the sintered body of this embodiment and the other components are bonded together. For example, it may be a composite in which two or more other components are joined together by the sintered body of this embodiment, or it may be a composite in which one other component is bonded to the sintered body of this embodiment. Examples of materials for the other components include metallic materials such as copper, gold, and aluminum; semiconductor materials such as silicon (Si), germanium, gallium arsenide, gallium phosphide, cadmium sulfide, silicon nitride, graphite, yttrium oxide, magnesium oxide, silicon carbide (SiC), and gallium nitride; plastic materials such as polyimide, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, and polyethylene naphthalate; and ceramic materials such as glass. Other components mentioned above include, for example, substrates, semiconductor elements, LED elements, leads, frames, heat sinks, etc.

[0061] [Firing Composition] The firing composition of this embodiment is a firing composition that contains the firing binder of this embodiment and one or more sintering particles selected from the group consisting of metal oxide precursor particles and metal oxide particles.

[0062] <Binder for firing> The description of the binder for firing contained in the firing composition of this embodiment is as described above. One type of binder for firing may be used alone, or two or more types may be used in combination. The content of aliphatic polycarbonate (A) in the firing composition of this embodiment is preferably 1 to 30% by mass, more preferably 1.2 to 25% by mass, even more preferably 1.5 to 20% by mass, and even more preferably 2 to 15% by mass, based on the total mass (100% by mass) of all components other than the solvent.

[0063] <Sintering Particles> The sintering particles are one or more selected from the group consisting of metal oxide precursor particles and metal oxide particles. The sintering particles form a sintered body when the firing composition of this embodiment is fired. Metal oxide precursor particles are a general term for substances that can become metal oxides when fired in an oxygen atmosphere. Depending on the intended use of the sintered body to be manufactured, the metal oxide precursor particles may be used in a manner that transforms them into metal oxides during the manufacturing process of the sintered body, or they may be used in a manner that forms a sintered body composed of metal oxide precursors without transforming them into metal oxides. One type of sintering particle may be used alone, or two or more types may be used in combination.

[0064] Examples of metal oxide precursor particles include gold particles, silver particles, copper particles, aluminum particles, nickel particles, tungsten particles, silicon carbide particles, silicon nitride particles, and aluminum nitride particles. Copper particles may consist solely of copper or of a copper alloy. Similarly, aluminum particles may consist solely of aluminum or of an aluminum alloy. Examples of metal oxide particles include oxides of the metal oxide precursor particles described above.

[0065] Average particle size of sintering particles (D ５０ The average particle size (D) of the particles for sintering is preferably 0.3 to 15 μm, more preferably 0.8 to 10 μm, and even more preferably 1 to 6 μm. ５０ This can be measured, for example, by laser diffraction and scattering methods.

[0066] The content of sintering particles in the firing composition of this embodiment is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, even more preferably 80 to 97% by mass, and even more preferably 85 to 96% by mass, based on the total mass (100% by mass) of all components other than the solvent.

[0067] <Solvent> The calcination composition of this embodiment may further contain a solvent. A calcination composition containing a solvent is suitable as a paste-like calcination composition. One solvent may be used alone, or two or more solvents may be used in combination.

[0068] Examples of solvents include ketones such as methyl ethyl ketone (2-butanone), methyl isobutyl ketone, cyclohexanone, acetylacetone, and isophorone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated carbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate, and butyl acetate; isopropanol, butanol, cyclohexanol, 1-decanol, and isobornyl. Examples include alcohols such as cyclohexanol; cellosolves such as methyl cellosolve and ethyl cellosolve; glycol ethers or glycol ether acetates such as butyl carbitol, propylene glycol monomethyl ether acetate, butyl carbitol acetate (diethylene glycol monobutyl ether acetate), and ethyl carbitol acetate (diethylene glycol monoethyl ether acetate); cellosolve acetates; sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide and dimethylacetamide; and so on.

[0069] The solvent content in the calcination composition of this embodiment may be adjusted as appropriate depending on the form of the calcination composition of this embodiment. If the calcination composition of this embodiment contains a solvent, the solvent content is preferably 1 to 40% by mass, more preferably 2 to 35% by mass, even more preferably 3 to 30% by mass, and even more preferably 4 to 25% by mass, based on the total mass (100% by mass) of the calcination composition.

[0070] <Other Optional Components> The firing composition of this embodiment may further contain other optional components other than the firing binder and sintering particles of this embodiment. Examples of other optional components include sintering aids, surfactants, and the same optional components that may be contained in the firing binder of this embodiment. Examples of sintering aids include fluorides such as aluminum fluoride, potassium fluoride, and calcium fluoride. Examples of surfactants include betaine-based, sulfobetaine-based, and alkylbetaine-based surfactants.

[0071] The total content of the firing binder and sintering particles in the firing composition of this embodiment is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, even more preferably 97 to 100% by mass, and even more preferably 99 to 100% by mass, based on the total mass (100% by mass) of all components other than the solvent, and may also be 100% by mass.

[0072] <Form of the firing composition> The form of the firing composition in this embodiment is not particularly limited and may be in the form of a paste or a film.

[0073] The thickness of the film-like firing composition is not particularly limited and can be determined appropriately depending on the application, but from the viewpoint of film formation properties and versatility, it is preferably 50 to 5000 μm, more preferably 100 to 4000 μm, and even more preferably 200 to 3000 μm.

[0074] <Method for Manufacturing the Firing Composition> The method for manufacturing the firing composition of this embodiment is not particularly limited and can be manufactured by mixing a firing binder, sintering particles, and a solvent and other optional components as needed. The method of mixing each component is not particularly limited and, for example, known mixing methods using mixing equipment such as a rotary-orbiting agitator, kneader, three-roll mixer, ball mill, sand mill, planetary mixer, paint shaker, homomixer, homodisper, homogenizer, and ultrasonic disperser can be employed. A paste-like firing composition can be manufactured by mixing the firing binder, sintering particles, and solvent by the above method. A film-like firing composition can be manufactured by coating and drying the paste-like firing composition obtained by the above method.

[0075] [Method for Manufacturing a Sintered Body] The method for manufacturing a sintered body according to this embodiment (hereinafter also referred to as "the manufacturing method of this embodiment") is a method for manufacturing a sintered body that involves heating the firing composition of this embodiment. The sintered body manufactured by the manufacturing method of this embodiment may be a metal oxide precursor sintered body or a metal oxide sintered body. The shape of the sintered body manufactured by the manufacturing method of this embodiment is not particularly limited and can be any desired shape, such as layered, plate-shaped, or block-shaped.

[0076] In the method for manufacturing a sintered body according to this embodiment, first, the firing composition is molded into a desired shape. When manufacturing a layered sintered body, it is preferable to mold it by applying a paste-like firing composition to a desired object and then removing the solvent by drying. Examples of such objects include other components described in the section "Uses of the firing binder" above. When manufacturing plate-shaped, block-shaped, or other sintered bodies, the firing composition can be molded by filling a desired mold or the like. Next, it is preferable to degrease the firing composition molded into the desired shape to obtain a sintered body precursor. Degreasing is a process to remove organic matter from the firing composition, and the degreasing method is not particularly limited, but examples include heating the firing composition in a heating furnace. The degreasing temperature is preferably below the 99% thermal decomposition temperature of aliphatic polycarbonate (A). This allows for the thermal decomposition of a portion of the firing binder, thereby obtaining a sintered body precursor. In this embodiment, since the firing composition contains aliphatic polycarbonate (A), which has excellent low-temperature decomposition properties, degreasing can be performed at a relatively low temperature. The degreasing temperature may be, for example, 200 to 400°C, 210 to 350°C, or 220 to 300°C. The degreasing time may be appropriately selected to allow sufficient degreasing of the baking binder, for example, 0.05 to 5 hours, 0.07 to 3 hours, or 0.1 to 1 hour.

[0077] The heating atmosphere during degreasing may be an oxygen atmosphere such as air, or an oxygen-free atmosphere, but an oxygen-free atmosphere is preferred from the viewpoint of preventing oxidation of the metal oxide precursor. The partial pressure of oxygen in the oxygen-free atmosphere is preferably 5.0 kPa or less, more preferably 3.0 kPa or less, even more preferably 1.0 kPa or less, even more preferably 0.5 kPa or less, and particularly preferably 0.1 kPa or less, from the viewpoint of preventing oxidation of the metal oxide precursor. The aliphatic polycarbonate (A) contained in the firing binder of this embodiment exhibits low-temperature decomposition even in an oxygen-free atmosphere, so it can be degreased at a relatively low temperature, thereby preventing oxidation of the metal oxide precursor. The oxygen-free atmosphere may be a single-gas atmosphere, a mixed-gas atmosphere, or a vacuum atmosphere. Examples of single gases include nitrogen, argon, helium, ammonia, and formaldehyde. Examples of mixed gases include forming gases, and examples of forming gases include nitrogen gas mixed with 5% by volume or less of hydrogen. Among these, a nitrogen atmosphere is preferred. The pressure conditions during degreasing may be atmospheric pressure, reduced pressure, or pressurized pressure.

[0078] Next, the degreased sintered body precursor is fired to obtain a sintered body. The firing method is not particularly limited and includes methods such as heating in a heating furnace.

[0079] In the manufacturing method of this embodiment, the firing temperature is preferably between half and below the melting point (absolute temperature) of the material to be fired. This causes the firing binder to decompose thermally, and the sintering particles to solidify, resulting in a sintered body. The firing time can be appropriately selected to allow the sintering particles to be sufficiently sintered, for example, it may be 0.1 to 48 hours, 1 to 36 hours, or 5 to 24 hours. The sintering atmosphere may be an oxygen atmosphere such as air, or an oxygen-free atmosphere, but an oxygen-free atmosphere is preferred from the viewpoint of preventing oxidation of the metal oxide precursor powder. The preferred form of the oxygen-free atmosphere is the same as the preferred form of the heating atmosphere during degreasing. The pressure conditions of the sintering atmosphere may be atmospheric pressure, reduced pressure, or increased pressure.

[0080] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0081] [Measurement of Mass-Average Molecular Weight (Mw)] The mass-average molecular weight (Mw) of the polymers produced in each example was measured using a gel permeation chromatograph (Tosoh Corporation, product name "HLC-8320") under the following conditions, and the results were expressed in terms of standard polystyrene. The results are shown in Table 1. <GPC Measurement Conditions> ・Column: "TSK guard column SuperH-H", "TSK gel SuperHM-H", "TSK gel SuperHM-H", and "TSK gel SuperH2000" (all manufactured by Tosoh Corporation) linked in sequence ・Column temperature: 40℃ ・Developing solvent: Tetrahydrofuran (calcination binder concentration 1% by mass) ・Injection volume: 20 μl ・Flow rate: 0.6 mL / min ・Detector: Differential refractometer ・Standard sample: Polystyrene

[0082] [Measurement of Glass Transition Temperature (Tg)] The glass transition temperature (Tg) of the polymers produced in each example and the comparative polymer was determined by differential scanning calorimetry (DSC) using a DSC Q2000 manufactured by T.A. Instruments Japan Co., Ltd. Specifically, an aluminum pan was used as the container, and under a nitrogen atmosphere, the temperature was increased from -70°C to 150°C at a rate of 10.0°C / min, held for 5 minutes, then cooled to -70°C at a rate of 10.0°C / min, held for 5 minutes, and then increased to 150°C at a rate of 10.0°C / min for measurement. The results are shown in Table 1.

[0083] [Measurement of ether ratio] The polymer produced in each example is used as the measurement target, under the following conditions: １ 1H-NMR measurements were performed, and the results were obtained. １ In the 1H-NMR spectrum, the integral value A from 4.7 to 5.2 ppm was taken as 1H (one hydrogen), indicating the presence of one carbonate bond, and the integral value B from 3.2 to 3.9 ppm was taken as 3H (three hydrogens), indicating the presence of one ether bond. The ether ratio, which is the content of ether bonds relative to the total amount of carbonate bonds and ether bonds (100 mol%) in each polymer, was calculated using the following formula. The results are shown in Table 1. Ether ratio (mol%) = (B / 3) × 100 / [A + (B / 3)] １ H-NMR measurement conditions: Equipment: Bruker, product name "AV-500" １ H-NMR resonance frequency: 500 MHz Probe: 5 mmφ solution probe Deuterated solvent: Deuterated chloroform (CDCl) ３ ) Internal standard substance: TMS (tetramethylsilane) Sample amount: 20-50 mg Measurement temperature: 25°C Number of cumulative measurements: 16 (Method of preparing measurement samples) The measurement sample was dissolved in deuterated chloroform containing TMS as an internal standard so that the measurement sample concentration was 3% by mass. １ The sample used for 1H-NMR measurement was selected.

[0084] [Synthesis of Metal Catalysts] Production Example 1 (Synthesis of Zinc Glutarate) 160 g of zinc oxide, 249 g of glutaric acid, and 2000 g of zirconia balls were placed in a 1000 mL polypropylene container with a lid in air, and the container was sealed with the lid. The polypropylene container was placed on the rotating rollers of a ball mill stand (manufactured by Ito Seisakusho Co., Ltd., product name "BMU-100") set on a horizontal table, and the reaction was carried out by rotating it at a set rotation speed of 220 rpm at room temperature (23°C) for 5 hours. The zirconia balls were removed by sieving, and the resulting white powder was dried in a vacuum dryer at 120°C for 5 hours to obtain zinc glutarate.

[0085] Manufacturing Example 2 (Synthesis of DMC Catalyst) Potassium hexacyanocobalt(III) (K ３ [Co(CN) ６ Dissolve 1.33 g in 20 mL of deionized water and stir vigorously to make a zinc chloride solution at 50°C (11.42 g of ZnCl). ２ The Zn catalyst was added dropwise over 45 minutes to a mixture of 60 mL of deionized water and 30 mL of t-butyl alcohol. The mixture was then vigorously stirred for 60 minutes. The resulting white suspension was centrifuged at 5000 rpm to isolate the white solid. The isolated white solid was resuspended in a mixture of t-butyl alcohol and deionized water (volume ratio: t-butyl alcohol:deionized water = 5:5) while being vigorously stirred for 30 minutes. Subsequently, the amount of t-butyl alcohol relative to water was gradually increased (changing the volume ratio of t-butyl alcohol:deionized water from 6:4 to 7:3, 8:2, and 9:1), and isolation by centrifugation and resuspension were repeated several times. Finally, the white solid was resuspended in t-butyl alcohol and isolated by centrifugation. The Zn catalyst was then dried at 50°C under vacuum until a predetermined mass was obtained. ３ (Co[CN] ６ ) ２ I obtained it.

[0086] Preparation Example 3 (Synthesis of Cobalt Salen Complex) (R,R)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt(II) and pentafluorobenzoic acid were weighed in a molar ratio of 1:1.1 and placed in a flask, to which anhydrous toluene was added. The flask was shielded from light with aluminum foil and reacted at 23°C for 20 hours with stirring. The chemical reaction equation is as follows. After the reaction was complete, the solvent was removed under reduced pressure and washed several times with an excess amount of hexane. Then, the mixture was vacuum dried at 23°C to obtain the cobalt salen complex, which is the product of the chemical reaction equation shown below.

[0087]

[0088] [Production of Binder for Calcination] Example 1 (Synthesis of Polybutylene Carbonate 1) 415 parts by mass of 1,2-butylene oxide as a raw material monomer and 83 parts by mass of zinc glutarate prepared in Production Example 1 as a polymerization catalyst were mixed with 1075 parts by mass of toluene to obtain a mixture. Next, the system of a 2 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 4 MPa. After that, the temperature was raised to 70°C, and the polymerization reaction was carried out for 4 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with toluene, and the catalyst was removed by filtration. The obtained solution was dried under reduced pressure to obtain polybutylene carbonate 1 as a binder for calcination.

[0089] Example 2 (Synthesis of Polybutylene Carbonate 2) 415 parts by mass of 1,2-butylene oxide as a raw material monomer, 83 parts by mass of zinc glutarate prepared in Production Example 1 as a polymerization catalyst, and 3.0 parts by mass of n-butanol as an additive were mixed with 1075 parts by mass of toluene to obtain a mixture. Next, the system of a 2 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 4 MPa. Then, the temperature was raised to 70°C, and the polymerization reaction was carried out for 4 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with toluene, the catalyst was removed by filtration, and reprecipitation purification was performed. The obtained solution was dried under reduced pressure to obtain polybutylene carbonate 2 as a binder for calcination.

[0090] Example 3 (Synthesis of Polybutylene Carbonate 3) 500 parts by mass of 1,2-butylene oxide as a raw material monomer and 0.5 parts by mass of DMC catalyst prepared in Production Example 2 as a polymerization catalyst were dissolved in 500 parts by mass of ethyl acetate to obtain a mixture. Next, the system of a 4 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 4 MPa. Then, the temperature was raised to 60°C, and the polymerization reaction was carried out for 18 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with ethyl acetate, and the catalyst was removed by reprecipitation purification. The obtained solution was dried under reduced pressure to obtain polybutylene carbonate 3 as a binder for calcination.

[0091] Comparative Example 1 (Synthesis of Polybutylene Carbonate 4) 1,600 parts by mass of 1,2-butylene oxide as a raw material monomer, 9 parts by mass of cobalt salen complex prepared in Production Example 3 as a polymerization catalyst, and 6.3 parts by mass of bis(triphenylphosphoranylidene)ammonium chloride as a co-catalyst were dissolved in 400 parts by mass of toluene to obtain a mixture. Next, the system of a 4 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 3 MPa. Then, the temperature was raised to 40°C, and the polymerization reaction was carried out for 5 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with toluene, and the catalyst was removed by reprecipitation purification. The obtained solution was dried under reduced pressure to obtain polybutylene carbonate 4 as a binder for calcination.

[0092] Comparative Example 2 (Synthesis of Polypropylene Carbonate 1) 500 parts by mass of propylene oxide as a raw material monomer and 125 parts by mass of zinc glutarate prepared in Production Example 1 as a polymerization catalyst were mixed with 500 parts by mass of toluene to obtain a mixture. Next, the system of a 2 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 4 MPa. After that, the temperature was raised to 70°C, and the polymerization reaction was carried out for 4 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with toluene, and the catalyst was removed by filtration. The obtained solution was dried under reduced pressure to obtain polypropylene carbonate 1 as a binder for calcination.

[0093] Comparative Example 3 (Synthesis of Polypropylene Carbonate 2) 1,437 parts by mass of propylene oxide as a raw material monomer, 10.1 parts by mass of cobalt salen complex prepared in Production Example 3 as a polymerization catalyst, and 7.1 parts by mass of bis(triphenylphosphoranylidene)ammonium chloride as a co-catalyst were dissolved in 479 parts by mass of ethyl acetate to obtain a mixture. Next, the system of a 4 L autoclave equipped with a stirrer, gas inlet pipe and thermometer was pre-filled with a nitrogen atmosphere, and the above mixture was charged in. Subsequently, while stirring the mixture in the autoclave, carbon dioxide gas was filled into the reaction system until the pressure reached 3 MPa. Then, the temperature was raised to 40°C, and the polymerization reaction was carried out for 5 hours while replenishing the carbon dioxide consumed by the reaction. After the reaction was completed, the autoclave was cooled and depressurized, the contents were diluted with ethyl acetate, and the catalyst was removed by reprecipitation purification. The obtained solution was dried under reduced pressure to obtain polypropylene carbonate 2 as a binder for calcination.

[0094] Comparative Example 4: Butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name "BL-1") was prepared as a comparative polymer.

[0095] Comparative Example 5: As a comparative polymer, an acrylic resin (manufactured by Kyoeisha Chemical Co., Ltd., product name "Oricox KC-1300") was prepared.

[0096] Comparative Example 6: Ethyl cellulose (manufactured by Dow Chemical Japan Ltd., product name "ETHOCEL Standard 7 Premium") was prepared as a comparative polymer.

[0097] [Evaluation Method] The firing binder obtained above was evaluated by the following method. The results are shown in Table 1.

[0098] [Method for measuring Young's modulus and breaking strength] The firing binder and comparative polymer obtained in each example were sandwiched between two release films (38 μm thick, manufactured by Lintec Corporation, product name "SP-PET382150") and pressed at 100°C (Examples 1-3, Comparative Examples 1-3, 5) or 120°C (Comparative Examples 4 and 6) and 4000 N using a screw-type heater press (manufactured by NPA System Co., Ltd., product name "N4046-00") to form a 200 μm thick polymer film with release films on both sides. After removing the release films from both sides of the polymer film obtained above, the film was cut into 10 mm x 50 mm pieces to be used as test specimens. These test specimens were mounted on a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph AG-Xplus") with a chuck distance of 30 mm, and the Young's modulus and breaking strength were measured at 23°C and a tensile speed of 200 mm / min.

[0099] [Thermal Decomposition Test] Using the calcination binder and comparative polymer obtained in each example as measurement samples, a thermal decomposition test was performed using a thermogravimetric analyzer (TGA; manufactured by Shimadzu Corporation, product name "DTG-60") under the conditions shown below. The temperature at which the mass reduction rate of the measurement sample reached 5%, 50%, or 99% was defined as the 5% thermal decomposition temperature (T), respectively. ｄ５ ), 50% thermal decomposition temperature (T ｄ５０ ) and 99% thermal decomposition temperature (T ｄ９９ ) was obtained as [a specific result]. In addition, the mass retention rate of the measured sample at 500°C in the pyrolysis test was defined as the 500°C residue rate. (TGA measurement conditions) Heating rate: 10°C / min Sample amount: 20-30 mg Measurement temperature range: 40-500°C Measurement pressure: atmospheric pressure Measurement atmosphere: air or nitrogen atmosphere with oxygen partial pressure of 0.1 kPa or less

[0100] *1: This means that the mass loss rate did not reach 99% in the thermal decomposition test.

[0101] Table 1 shows that the firing binder of this embodiment has a low Young's modulus, good fracture strength, and excellent thermal decomposition properties.

Claims

1. A firing binder containing an aliphatic polycarbonate, wherein the aliphatic polycarbonate has substituted or unsubstituted carbon-2 hydrocarbon groups in its side chains that are directly bonded to the main chain, and the mass-average molecular weight (Mw) of the aliphatic polycarbonate is 200,000 or more.

2. The firing binder according to claim 1, wherein the aliphatic polycarbonate has structural units represented by the following general formula (1a). (In the formula, R １ , R ２ , R ３ and R ４ Each is independently a hydrogen atom or a substituted or unsubstituted C2 hydrocarbon group, R １ , R ２ , R ３ and R ４ (At least one of these is the aforementioned substituted or unsubstituted C2 hydrocarbon group.) 3. Only any one of R １ , R ２ , R ３ and R ４ in the above general formula (1a) is the substituted or unsubstituted hydrocarbon group having 2 carbon atoms, the binder for firing according to claim 2.

4. The calcination binder according to any one of claims 1 to 3, wherein the substituted or unsubstituted carbon-2 hydrocarbon group is an unsubstituted carbon-2 hydrocarbon group.

5. The firing binder according to any one of claims 1 to 3, wherein the aliphatic polycarbonate does not contain ether bonds, or the aliphatic polycarbonate contains ether bonds, and the content of the ether bonds is 20 mol% or less with respect to the total amount of carbonate bonds and ether bonds (100 mol%).

6. A firing composition comprising a firing binder according to any one of claims 1 to 3, and one or more sintering particles selected from the group consisting of metal oxide precursor particles and metal oxide particles.

7. The baking composition according to claim 6, which is in the form of a paste.

8. The firing composition according to claim 6, which is in the form of a film.

9. A method for producing a sintered body, comprising heating the firing composition described in claim 6.

10. The method for producing a sintered body according to claim 9, wherein the firing composition is heated in an atmosphere with an oxygen partial pressure of 5.0 kPa or less.

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