Binders for sintering and paste compositions for sintering

Abstract

The present invention provides a binder for sintering, which contains an aliphatic polycarbonate having a carbonate structure in a main chain and a hydrocarbon group having 2 to 8 carbon atoms in a side chain, wherein the aliphatic polycarbonate has a weight average molecular weight of 50,000 or more and 170,000 or less. The aliphatic polycarbonate preferably has a structural unit represented by the following general formula (1a). According to the binder for sintering, solid substances of carbon compounds from the binder are not left in a sintered body, carbon dioxide can be used as a raw material for production, carbon dioxide is not substantially emitted at the time of sintering, and adhesion to a metal is high. In the formula, R 1 , R 2 , R 3 , and R 4 are each independently a hydrogen atom or a hydrocarbon group, and at least one is a hydrocarbon group having 2 to 8 carbon atoms.

Description

Technical Field

[0001] This invention relates to binders for firing and paste compositions for firing. Background Technology

[0002] Sintered bodies made from inorganic powders such as sintered metal powder and ceramic powder have been used in various fields, such as in the manufacture of electrodes, conductor wiring, and multilayer capacitors in various electronic devices.

[0003] To manufacture the sintered body described above, a mixture of inorganic powder and a binder for firing, i.e., a paste composition for firing, is formed into the desired shape and preheated as needed, followed by firing to sinter the inorganic powder.

[0004] As a binder for firing as described above, for example, Patent Document 1 discloses a low-temperature firing binder resin composition, which, relative to 100 parts by weight of a (meth)acrylate polymer (A) having functional groups capable of forming hydrogen bonds with hydroxyl groups, contains 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 (C) having a boiling point of 150°C or higher. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-160791 Summary of the Invention (a) Technical problems to be solved

[0006] However, for acrylic binders used in firing, such as those in Patent Document 1, there is a problem that solid carbon compounds remain in the sintered body after firing.

[0007] Furthermore, depending on the intended use of the sintered body, it is sometimes required that the sintered body or the binder used for firing has good adhesion to the metal components it contacts (e.g., copper, aluminum, etc.). However, acrylic-based binders used for firing, such as those in Patent Document 1, have low adhesion to metals, requiring the use of additives to improve adhesion.

[0008] On the other hand, in recent years, global warming and the resulting environmental damage have become major problems, with carbon dioxide considered one of the main causes. Therefore, suppressing carbon dioxide emissions and effectively utilizing emitted carbon dioxide during the production of various materials is beneficial to environmental protection.

[0009] The present invention was made in view of the above-mentioned actual situation, and its purpose is to provide a binder for firing and a paste composition for firing, wherein the binder for firing does not leave solid carbon compounds from the binder in the sintered body, can use carbon dioxide as a manufacturing raw material, emits virtually no carbon dioxide during firing, and has high adhesion to metals. (II) Technical Solution

[0010] To achieve the above objectives, firstly, the present invention provides a binder for firing, which contains an aliphatic polycarbonate having a carbonate structure in the main chain and a hydrocarbon group having 2 to 8 carbon atoms in the side chain. The binder for firing is characterized in that the weight-average molecular weight of the aliphatic polycarbonate is 50,000 or more and 170,000 or less (Invention 1).

[0011] The aliphatic polycarbonate of the above-mentioned invention (Invention 1) decomposes primarily into cyclic carbonates during firing, thus virtually eliminating carbon dioxide emissions during firing and minimizing the residue of solid carbon compounds from the binder in the sintered body. Furthermore, since the weight-average molecular weight of the aliphatic polycarbonate is relatively low, between 50,000 and 170,000, it is even less likely to leave carbon compounds from the binder in the sintered body. In addition, the cyclic carbonates produced can be recycled in solvents or electrolytes for lithium-ion batteries. Moreover, since the aliphatic polycarbonate can be manufactured using carbon dioxide as a raw material, efficient utilization of carbon dioxide is possible. Furthermore, because the aliphatic polycarbonate has hydrocarbon groups with 2 to 8 carbon atoms in its side chains, it is easier to lower the glass transition temperature to below room temperature, improving wettability to the adhered material and thus exhibiting excellent adhesion to metals at room temperature.

[0012] In the above invention (Invention 1), it is preferable that the 50% thermal decomposition temperature of the binder used for firing is 255°C or higher and 300°C or lower in an atmosphere with atmospheric pressure and oxygen concentration of 5% or less (Invention 2).

[0013] In the above inventions (Inventions 1 and 2), it is preferred that the 99% thermal decomposition temperature of the binder used for firing is below 400°C in an atmosphere with atmospheric pressure and oxygen concentration of 5% or less (Invention 3).

[0014] In the above inventions (Inventions 1 to 3), it is preferable that the adhesion force measured when peeling the layer of the adhesive for firing from an aluminum plate having a layer of 20 μm thickness formed on it at a peeling angle of 180° and a peeling speed of 300 mm / min is 0.3 N / 25 mm or more (Invention 4).

[0015] In the above inventions (Inventions 1 to 4), it is preferred that the hydrocarbon group having 2 to 8 carbon atoms is a straight-chain hydrocarbon group (Invention 5).

[0016] In the above inventions (Inventions 1-5), it is preferable that the aliphatic polycarbonate has a structural unit represented by the following general formula (1a) (Invention 6). [Chemical Formula 1] In general formula (1a), R 1 R 2 R 3 and R 4 Each is independently a hydrogen atom or a hydrocarbon group, and at least one of them is a hydrocarbon group with 2 to 8 carbon atoms.

[0017] In the above inventions (Inventions 1 to 6), it is preferred that: the binder for firing is used to form a metal oxide precursor sintered body or to form a metal oxide sintered body (Inventions 7 and 8); or the binder for firing is used to form a metal oxide precursor sintered foil on a substrate or to form a metal oxide sintered foil on a substrate (Inventions 9 and 10).

[0018] In the above inventions (Inventions 1 to 10), it is preferred that the binder used for firing has a storage modulus of 1.0 MPa or more and 50 MPa or less at 23°C (Invention 11).

[0019] In the above inventions (Inventions 1 to 11), it is preferred that the glass transition temperature (Tg) of the binder used for firing is above -15°C and below 25°C (Invention 12).

[0020] In the above inventions (Inventions 1 to 12), it is preferable that the binder for firing is formed to have a thickness of 0.5 mm and a width of 10 mm, and when stretched at a measuring temperature of 23°C, a measuring length of 10 mm, and a stretching speed of 200 mm / min, the elongation at break is 100% or more (Invention 13).

[0021] In the above inventions (Inventions 1 to 13), it is preferable that the binder for firing is formed to have a thickness of 0.5 mm and a width of 10 mm, and is stretched at a measuring temperature of 23°C, a measuring length of 10 mm, and a stretching speed of 200 mm / min until the maximum stress at the elongation at break is 10 MPa or less (Invention 14).

[0022] Second, the present invention provides a paste composition for firing, which contains metal oxide precursor powder or metal oxide powder and the binder for firing (Invention 1-14) (Invention 15).

[0023] Furthermore, in this specification, "metal oxide precursor" refers to the general term for substances that can form metal oxides when sintered in an oxygen atmosphere. However, it does not presuppose that sintering is carried out in an oxygen atmosphere. Additionally, in this specification, "metal oxide precursor sintered foil" refers to a composite material of a sintered metal oxide precursor and a foil-like component such as a metal foil. (III) Beneficial Effects

[0024] The binder and paste composition for firing according to the present invention do not leave solid carbon compounds from the binder in the sintered body, can use carbon dioxide as a manufacturing raw material, emit virtually no carbon dioxide during firing, and have high adhesion to metals. Detailed Implementation

[0025] The following describes the embodiments of the present invention. [Binder used for firing] The binder for firing in one embodiment of the present invention (hereinafter sometimes referred to as "binder B for firing") contains an aliphatic polycarbonate (hereinafter sometimes referred to as "aliphatic polycarbonate A") having a carbonate structure in the main chain and hydrocarbon groups having 2 to 8 carbon atoms in the side chains.

[0026] When aliphatic polycarbonate A decomposes during firing, the main byproducts are cyclic carbonates. Therefore, it emits virtually no carbon dioxide during firing and is unlikely to leave solid carbon compounds from the binder in the sintered body. Furthermore, because aliphatic polycarbonate A has a relatively low weight-average molecular weight of 50,000 to 170,000, it is even less likely to leave carbon compounds from the binder in the sintered body (this effect is sometimes referred to as "carbon residue inhibition"). In addition, the cyclic carbonates produced can be recycled in solvents or electrolytes for lithium-ion batteries. Moreover, as described later, aliphatic polycarbonate A can be manufactured using carbon dioxide as a raw material, thus enabling the efficient utilization of carbon dioxide.

[0027] Furthermore, aliphatic polycarbonate A, by having hydrocarbon groups with 2 to 8 carbon atoms in its side chains, readily achieves a glass transition temperature below room temperature and improves wettability to the adherends, thus exhibiting excellent adhesion to metals at room temperature. Specifically, it exhibits excellent adhesion between the sintering paste composition using sintering binder B and the metal component, excellent adhesion between the metal oxide precursor powders in the sintering paste composition containing sintering binder B and metal oxide precursor powder, and excellent adhesion between metal components via sintering binder B (sintering paste composition). Conversely, adhesion to the adherends at room temperature is low only when the hydrocarbon groups in the side chains of aliphatic polycarbonate A have 0 or 1 carbon atoms.

[0028] Furthermore, aliphatic polycarbonate A, by having a carbonate structure in its main chain, exhibits low-temperature decomposition properties through a specific reaction, specifically through a backbiting reaction. Therefore, the binder B for firing according to the embodiment can be fired at a lower temperature. This low-temperature decomposition property of the aliphatic polycarbonate A is effective not only in air but also in inert atmospheres. Therefore, even in the presence of metals that are easily oxidized during firing in air, oxidation of the metals can be prevented in an inert atmosphere, allowing for firing at a lower temperature.

[0029] Furthermore, by making the weight-average molecular weight of aliphatic polycarbonate A relatively low, between 50,000 and 170,000, the coatability and processability of the paste composition (slurry) containing aliphatic polycarbonate A for firing become good.

[0030] From the perspective of the above-mentioned effects, especially the inhibition of residual carbon, the weight-average molecular weight (Mw) of aliphatic polycarbonate A is preferably 50,000 to 160,000, particularly preferably 54,000 to 120,000, and even more preferably 58,000 to 80,000. The weight-average molecular weight (Mw) and the number-average molecular weight (Mn) mentioned below in this specification are values ​​converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0031] The number-average molecular weight (Mn) of aliphatic polycarbonate A is preferably 10,000 to 150,000, more preferably 15,000 to 100,000, particularly preferably 20,000 to 80,000, and even more preferably 30,000 to 60,000. This results in superior performance, especially in terms of carbon residue suppression.

[0032] The molecular weight distribution PDI (Mw / Mn) of aliphatic polycarbonate A is preferably 1.00 to 7.00, more preferably 1.05 to 5.00, particularly preferably 1.10 to 3.00, and even more preferably 1.15 to 2.00.

[0033] The 99% thermal decomposition temperature of aliphatic polycarbonate A in an atmosphere with atmospheric pressure and an oxygen concentration of 5% or less is preferably 400°C or less, more preferably 380°C or less, more preferably 350°C or less, particularly preferably 320°C or less, and even more preferably 310°C or less. Therefore, even in an inactive atmosphere, aliphatic polycarbonate A exhibits excellent low-temperature decomposition properties, and firing can be performed at a relatively low temperature even in an inactive atmosphere. In this embodiment, the 99% thermal decomposition temperature described above can be achieved by using aliphatic polycarbonate A. The lower limit of the 99% thermal decomposition temperature is not particularly limited, but from the perspective of allowing the solvent to evaporate at a temperature above its boiling point after coating the slurry, it is preferably 270°C or more, particularly preferably 280°C or more, and even more preferably 290°C or more. Furthermore, the thermal decomposition temperature in this specification is determined by thermogravimetric analysis (TGA), as detailed in the test examples described later.

[0034] The 50% thermal decomposition temperature of aliphatic polycarbonate A in an atmosphere with atmospheric pressure and an oxygen concentration of 5% or less is preferably 300°C or less, more preferably 295°C or less, more preferably 290°C or less, particularly preferably 285°C or less, and even more preferably 280°C or less. This facilitates good low-temperature decomposition in an inactive atmosphere. Furthermore, the lower limit of the aforementioned 50% thermal decomposition temperature is preferably 255°C or more, more preferably 260°C or more, particularly preferably 265°C or more, and even more preferably 270°C or more. This widens the boiling point difference with the solvent in the slurry, preventing the decomposition of aliphatic polycarbonate A when heating is performed after coating the slurry to allow the solvent to evaporate.

[0035] The 10% thermal decomposition temperature of aliphatic polycarbonate A in an atmosphere with atmospheric pressure and an oxygen concentration of 5% or less is preferably 285°C or less, more preferably 280°C or less, more preferably 275°C or less, particularly preferably 270°C or less, and even more preferably 265°C or less. The lower limit of the above-mentioned 10% thermal decomposition temperature is not particularly limited, but is preferably 210°C or more, particularly preferably 235°C or more, and even more preferably 250°C or more.

[0036] The 5% thermal decomposition temperature of aliphatic polycarbonate A in an atmosphere with atmospheric pressure and an oxygen concentration of 5% or less is preferably 280°C or less, more preferably 275°C or less, more preferably 270°C or less, particularly preferably 265°C or less, and even more preferably 260°C or less. The lower limit of the above-mentioned 5% thermal decomposition temperature is not particularly limited, but is preferably 210°C or more, particularly preferably 230°C or more, and even more preferably 245°C or more.

[0037] The 99% thermal decomposition temperature of aliphatic polycarbonate A in air is preferably below 395°C, more preferably below 375°C, more preferably below 345°C, particularly preferably below 315°C, and even more preferably below 305°C. This results in excellent low-temperature decomposition properties of aliphatic polycarbonate A, allowing for firing at lower temperatures. In this embodiment, the 99% thermal decomposition temperature described above can be achieved by using aliphatic polycarbonate A. While the lower limit of the 99% thermal decomposition temperature is not particularly limited, from the perspective of allowing the solvent to evaporate at a temperature above its boiling point after coating the slurry, it is preferably above 265°C, particularly preferably above 275°C, and even more preferably above 285°C.

[0038] The 50% thermal decomposition temperature of aliphatic polycarbonate A in air is preferably below 295°C, more preferably below 290°C, more preferably below 285°C, particularly preferably below 280°C, and even more preferably below 275°C. The lower limit of the above-mentioned 50% thermal decomposition temperature is not particularly limited, but is preferably above 250°C, particularly preferably above 255°C, and even more preferably above 260°C.

[0039] The 10% thermal decomposition temperature of aliphatic polycarbonate A in air is preferably below 280°C, more preferably below 275°C, more preferably below 270°C, particularly preferably below 265°C, and even more preferably below 260°C. The lower limit of the above-mentioned 10% thermal decomposition temperature is not particularly limited, but is preferably above 205°C, particularly preferably above 230°C, and even more preferably above 245°C.

[0040] The 5% thermal decomposition temperature of aliphatic polycarbonate A in air is preferably below 275°C, more preferably below 270°C, more preferably below 260°C, particularly preferably below 255°C, and even more preferably below 250°C. The lower limit of the above-mentioned 5% thermal decomposition temperature is not particularly limited, but is preferably above 200°C, particularly preferably above 225°C, and even more preferably above 240°C.

[0041] When peeling the layer of binder B (with a thickness of 20 μm) from an aluminum plate having a layer formed of binder B for firing at a peel angle of 180° and a peel speed of 300 mm / min, the adhesion force measured is preferably 0.3 N / 25 mm or more, more preferably 0.5 N / 25 mm or more, particularly preferably 1 N / 25 mm or more, and even more preferably 5 N / 25 mm or more. This results in high adhesion to the metal. In this embodiment, by using aliphatic polycarbonate A, the excellent metal adhesion described above can be achieved. The upper limit of the adhesion force is not particularly limited, but from the perspective that excessively high adhesion force would result in adhesiveness, it is preferably 20 N / 25 mm or less, particularly preferably 18 N / 25 mm or less, and even more preferably 15 N / 25 mm or less. The sealing force in this specification refers to the sealing force determined essentially by the 180-degree peel method according to JIS Z0237:2000, and the specific test method is shown in the test examples described later.

[0042] In this case, the hydrocarbon groups with 2 to 8 carbon atoms in aliphatic polycarbonate A are preferably straight-chain hydrocarbon groups. This makes it easier to satisfy the aforementioned adhesion requirements.

[0043] The glass transition temperature (Tg) of aliphatic polycarbonate A is preferably below 25°C, particularly preferably below 20°C, and even more preferably below 18°C. This results in excellent adhesion to metals, especially aluminum, at room temperature, easily achieving the aforementioned adhesion strength. In this embodiment, by using aliphatic polycarbonate A with 2 to 8 carbon atoms in the hydrocarbon groups of the side chains, the low glass transition temperature (Tg) described above can be achieved. From the perspective of film strength, the aforementioned glass transition temperature (Tg) is preferably above -15°C, more preferably above -8°C, particularly preferably above 0°C, and even more preferably above 10°C. The glass transition temperature (Tg) in this specification is determined by differential scanning calorimetry (DSC), as detailed in the experimental examples described later.

[0044] The storage modulus of aliphatic polycarbonate A at 23°C is preferably 50 MPa or less, more preferably 40 MPa or less, particularly preferably 30 MPa or less, and even more preferably 20 MPa or less. This results in excellent adhesion to metals at room temperature, especially to aluminum, making it easy to achieve the aforementioned adhesion strength. The lower limit of the aforementioned storage modulus is preferably 1.0 MPa or more, more preferably 2.0 MPa or more, particularly preferably 8 MPa or more, and even more preferably 12 MPa or more. This maintains excellent adhesion to metals at room temperature, especially to aluminum, making it easy to achieve the aforementioned adhesion strength. Furthermore, the method for determining the storage modulus in this specification is shown in the test examples described later.

[0045] When aliphatic polycarbonate A is formed to a thickness of 0.5 mm and a width of 10 mm, and a tensile test is performed at a test temperature of 23°C, a test length of 10 mm, and a tensile speed of 200 mm / min, the elongation at break is preferably 100% or more, more preferably 1000% or more, particularly preferably 3000% or more, and even more preferably 5000% or more. This results in excellent flexibility and a higher degree of freedom in designing the shape of the resulting sintered body. Furthermore, the specific method for the above tensile test is shown in the test examples described later.

[0046] The maximum stress of aliphatic polycarbonate A during the above-mentioned tensile test and stretching to the elongation at break is preferably 10 MPa or less, more preferably 7 MPa or less, particularly preferably 5 MPa or less, and even more preferably 3 MPa or less. This results in excellent flexibility and a higher degree of freedom in designing the shape of the resulting sintered body. The lower limit of the above-mentioned maximum stress is preferably 0.01 MPa or more. This ensures the strength required for producing the paste used in firing.

[0047] The ether bond ratio in aliphatic polycarbonate A is preferably 20% or less, more preferably 10% or less, particularly preferably 5% or less, and even more preferably 1% or less. This results in improved decomposability and superior carbon residue suppression. The method for determining the ether bond ratio in this specification is shown in the experimental examples described later. In addition, the -O- bond in the carbonate bond (-OC(=O)-O-) is not an ether bond.

[0048] 1. Ingredients The following describes the components contained in the binder B used for firing in this embodiment. (1) Aliphatic polycarbonate (1-1) Structure of aliphatic polycarbonate The aliphatic polycarbonate A used in the binder B for firing is a polycarbonate whose main chain consists only of carbonate groups (-OC(=O)-O-) and aliphatic groups, and has a structure in which the carbonate groups connect the divalent aliphatic groups that make up the main chain to each other.

[0049] The aforementioned aliphatic polycarbonate A may have carboxylic ester bonds (-C(=O)-O-) in its main chain, but preferably does not. When the aliphatic polycarbonate A does not have carboxylic ester bonds in its main chain, the aforementioned aliphatic polycarbonate A does not include polymers with a polycarbonate backbone obtained by reacting carboxylic acids or their derivatives with alcohols to form ester bonds in the main chain. Among the carboxylic acid derivatives, examples include carboxylic anhydrides and carboxylic halides, which are capable of forming ester bonds.

[0050] Furthermore, the aforementioned aliphatic polycarbonate A may have urethane bonds (-NH-C(=O)-O-) in its main chain, but preferably does not have urethane bonds. When the aliphatic polycarbonate A does not have urethane bonds in its main chain, the aforementioned aliphatic polycarbonate A does not include polymers with a polycarbonate backbone obtained by reacting compounds having isocyanate groups with alcohols to form urethane bonds in the main chain.

[0051] Furthermore, the aforementioned aliphatic polycarbonate A may have ether bonds (-O-) in its main chain.

[0052] Furthermore, aliphatic polycarbonate A may have or not have any one or both of carboxylic acid ester bonds and urethane bonds in its side chains. However, from the perspective of preventing metal corrosion, aliphatic polycarbonate A preferably does not have carboxylic acid ester bonds in its side chains.

[0053] As the aforementioned aliphatic polycarbonate A, for example, an aliphatic polycarbonate having the structural unit represented by the following general formula (1) can be listed.

[0054] [Chemical Formula 2] In general formula (1), X is a divalent aliphatic hydrocarbon group with substituents.

[0055] In general formula (1), X is a divalent aliphatic hydrocarbon group with substituents. This aliphatic hydrocarbon group can be any of the following: straight-chain, branched, and cyclic. It can also have both chain and cyclic structures. Furthermore, the cyclic aliphatic hydrocarbon group can be any of the following: monocyclic and polycyclic.

[0056] In X, an "aliphatic hydrocarbon group with substituents" refers to an aliphatic hydrocarbon group in which one or more hydrogen atoms are replaced by groups (substituents) other than hydrogen atoms.

[0057] The substituents of the aforementioned aliphatic hydrocarbon groups are not particularly limited, and examples include hydroxyl, halogen atoms, alkoxy, alkenyl, alkenyloxy, aryl, heteroaryl, aryloxy, heteroaryloxy, alkylsilyl group, and alkylsiloxy. Therefore, if the groups in the aforementioned aliphatic polycarbonate, excluding the carbonate groups constituting the main chain, are only aliphatic groups, then the side chains branching from the main chain may or may not contain aromatic groups. Furthermore, from the perspective of preventing metal corrosion, it is preferable to avoid the presence of carboxyl groups as substituents.

[0058] Examples of halogen atoms that can be used as substituents include fluorine, chlorine, bromine, and iodine atoms.

[0059] Examples of alkoxy groups among the above substituents include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropoxy, cyclobutoxy, etc., and those described below as R. 1 The same group as the alkoxy group in etc.

[0060] Examples of alkenyl groups among the aforementioned substituents include vinyl, allyl, 1-methylvinyl, 2-methylvinyl, 1-cyclohexenyl, 2-cyclohexenyl, 3-cyclohexenyl, and others, as well as those described below. 1 Groups that are the same as the alkenyl group in the above.

[0061] As the substituents mentioned above, the alkenyl group can be a monovalent group formed by bonding the oxygen atom of the aforementioned alkenyl group with the alkenyl group, for example, ethyleneoxy, 2-propenoxy, 1-methylethyleneoxy, 2-methylethyleneoxy, 1-cyclohexenoxy, 2-cyclohexenoxy, 3-cyclohexenoxy, etc.

[0062] The aryl group in the above-mentioned substituents can be either monocyclic or polycyclic, preferably having 6 to 13 carbon atoms. Examples include phenyl, 1-naphthyl, 2-naphthyl, o-tolyl, m-tolyl, p-tolyl, xylyl (dimethylphenyl), etc. Furthermore, one or more hydrogen atoms of these aryl groups may be further substituented by these aryl groups or by R (described later). 1 Alkyl-substituted groups of the same kind. Preferably, the aryl group having these substituents has 6 to 13 carbon atoms, including the substituent.

[0063] The heteroaryl group in the aforementioned substituents can be either monocyclic or polycyclic. For example, the heteroaryl group can be one of the following groups: a group in which one or more carbon atoms constituting the aromatic ring skeleton of the aforementioned aryl group are substituted by heteroatoms, either individually or together with hydrogen atoms bonded to those carbon atoms, and which is aromatic; or a group in which one or more carbon atoms constituting the ring skeleton of a cyclic unsaturated aliphatic hydrocarbon group having three or more carbon atoms are substituted by heteroatoms, either individually or together with hydrogen atoms bonded to those carbon atoms, and which is aromatic. Examples of heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, selenium atoms, and phosphorus atoms. However, from the perspective of safety and environmental protection of the decomposition products generated during firing, it is preferable that the decomposition products do not contain heteroatoms other than oxygen atoms, and particularly preferable that they do not contain nitrogen atoms and sulfur atoms. This is because decomposition products containing nitrogen atoms or sulfur atoms can sometimes form toxic gases. The number of heteroatoms constituting the aromatic ring skeleton is not particularly limited, but is preferably one to two. Furthermore, when there are two or more heteroatoms constituting the aromatic ring skeleton, these heteroatoms can be all the same, all different, or only some of them can be the same.

[0064] In addition, in this specification, for example, a group having a structure formed by the condensation of an aromatic hydrocarbon group and an aromatic heterocyclic group is referred to as an aromatic heterocyclic group.

[0065] As one of the above substituents, the aryl group can be, for example, a monovalent group formed by the bonding of an oxygen atom of phenoxy, 1-naphthoxy, 2-naphthoxy, etc., with the aforementioned aryl group.

[0066] As one of the above substituents, a heteroaryl group can be listed as a monovalent group formed by the bonding of an oxygen atom with the aforementioned heteroaryl group.

[0067] The alkylsilyl group in the above-mentioned substituents can be any one of monoalkylsilyl, dialkylsilyl, and trialkylsilyl. In this alkylsilyl group, the alkyl group bonded to the silicon atom can be any one of linear, branched, and cyclic structures, and can also have both chain and cyclic structures simultaneously. Furthermore, the cyclic alkyl group can be any one of monocyclic and polycyclic structures. Examples of alkyl groups bonded to the silicon atom include R, which will be described later. 1 The same group as the alkyl group in etc.

[0068] In the dialkylsilyl and trialkylsilyl groups mentioned above, the multiple alkyl groups can be the same or different from each other. In the trialkylsilyl group, all three alkyl groups can be the same, all different, or only two can be the same.

[0069] As substituents, alkylsiloxy groups include, for example, dimethylsiloxy, ethylmethylsiloxy, trimethylsiloxy, ethylmethyl-n-propylsiloxy, and ethyldimethylsiloxy, which are monovalent groups formed by bonding an oxygen atom to the aforementioned alkylsilyl group.

[0070] The number of substituents in the aliphatic hydrocarbon group is not particularly limited; it can be one, two or more, or all hydrogen atoms can be replaced by substituents. Preferably, the total number of carbon atoms in the aliphatic hydrocarbon group, including the substituents, is four or more. Furthermore, the total number of carbon atoms, including the substituents, is preferably 10 or less, more preferably 8 or less, and particularly preferably 6 or less. By keeping the total number of carbon atoms in the aliphatic hydrocarbon group within the above range, both layer-forming properties and decomposition properties can be achieved.

[0071] In the aliphatic hydrocarbon groups described above, when there are two or more substituents, these substituents can be the same as or different from each other. That is, two or more substituents can be all the same, all different, or only some can be the same. Furthermore, the bonding position of the substituents in the above-mentioned aliphatic hydrocarbon groups is not particularly limited, but it is preferable that the terminal portion of the substituent is the terminal portion of the side chain, which can be a carbon atom constituting the main chain in X, or a carbon atom at the end of the side chain.

[0072] The aliphatic hydrocarbon group with substituents described above is preferably an alkylene group with substituents, and more preferably an ethylene group with substituents. If the aliphatic hydrocarbon group is an alkylene group, especially an ethylene group, the glass transition temperature (Tg) of the aliphatic polycarbonate becomes lower, and its low-temperature decomposition is improved.

[0073] The aforementioned aliphatic polycarbonate A preferably has a structural unit represented by the following general formula (1a) (hereinafter sometimes abbreviated as "structural unit (1a)").

[0074] [Chemical Formula 3] In general formula (1a), R 1 R 2 R 3 and R 4 Each is independently a hydrogen atom or a hydrocarbon group, and at least one of them is a hydrocarbon group with 2 to 8 carbon atoms.

[0075] From the perspective of decomposition, it is preferable that the hydrocarbon group with 2 to 8 carbon atoms has a small number of carbon atoms, specifically, 2 is particularly preferred. From the perspective of adhesion, it is preferable that the number of carbon atoms is large, specifically, 8 is particularly preferred.

[0076] The aforementioned hydrocarbon groups are preferably each independently an unsubstituted or substituted alkyl or alkoxy group. The aforementioned hydrocarbon groups (alkyl, alkoxy) can be any of straight-chain, branched, and cyclic, and can simultaneously have both chain and cyclic structures; however, straight-chain is preferred from the perspective of easily satisfying the aforementioned physical properties, especially the glass transition temperature (Tg). Cyclic hydrocarbon groups can be any of monocyclic and polycyclic.

[0077] Examples of linear or branched alkyl groups include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, 2-methylpentyl, n-heptyl, 2-methylhexyl, 2-ethylhexyl, n-octyl, and isooctyl. Among these groups, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-octyl, or isooctyl are preferred from the perspective of easily satisfying the aforementioned physical properties, especially the glass transition temperature (Tg), and ethyl or n-octyl are particularly preferred.

[0078] Examples of cyclic alkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Further examples include groups in which one or more hydrogen atoms of these cyclic alkyl groups are substituted by straight-chain, branched, or cyclic alkyl groups. Among these, examples of straight-chain, branched, and cyclic alkyl groups that substitute hydrogen atoms include R... 1 ~R 4 The above-mentioned groups are exemplified by alkyl groups in the form of alkyl groups.

[0079] Examples of linear or branched alkoxy groups include ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, n-pentoxy, isopentoxy, n-hexyloxy, 2-methylpentoxy, n-heptoxy, 2-methylhexyloxy, 2-ethylhexyloxy, n-octoxy, and isooctoxy, where the oxygen atom is related to the R group. 1 ~R 4 It is a monovalent group formed by the bonding of straight-chain or branched alkyl groups.

[0080] As cyclic alkoxy groups, examples include cyclopropoxy, cyclobutoxy, cyclopentoxy, and cyclohexyloxy, where the oxygen atom is related to R. 1 ~R 4 It is a monovalent group formed by the cyclic alkyl bonds in the group.

[0081] When R 1 ~R 4 When the alkyl or alkoxy group has a substituent, the substituent can be, for example, hydroxyl, halogen atom, alkoxy, alkenyl, alkenoxy, aryl, heteroaryl, aryloxy, heteroaryloxy, alkylsilyl, alkylsiloxy, etc., and these substituents are the same as the substituents when the aforementioned aliphatic hydrocarbon group has a substituent.

[0082] R 1 ~R 4 The number of substituents in the alkyl or alkoxy group is not particularly limited; it can be one, two or more, or all hydrogen atoms can be substituted. Furthermore, the number of carbon atoms, including the substituents, in the alkyl or alkoxy group is preferably within the aforementioned range.

[0083] When R 1 ~R 4 When the alkyl or alkoxy group has two or more substituents, these substituents can be the same as or different from each other. That is, the two or more substituents can be all the same, all different, or only some of them can be the same.

[0084] The bonding position of the substituent in the alkyl or alkoxy group is not particularly limited. For example, when it is an alkyl group, it is preferred to be the terminal part (the carbon atom bonded to the ethylene of the alkyl group is the terminal carbon atom on the opposite side).

[0085] R as having substituents 1 ~R 4 For example, if it is an alkyl group with substituents, examples include hydroxyalkyl, haloalkyl, alkoxyalkyl, arylalkyl, heteroarylalkyl, aryloxyalkyl, heteroaryloxyalkyl, alkylsilylalkyl, alkylsiloxyalkyl, etc. When R is an alkyl group other than alkyl... 1 ~R 4When substituents are present, groups in which hydrogen atoms are replaced by substituents can also be listed.

[0086] In structural unit (1a), R is preferred. 1 ~R 4 At least one of them is an alkyl group having 2 to 8 carbon atoms, with R being particularly preferred. 1 ~R 4 One of them is an alkyl group with 2 to 8 carbon atoms. From the perspective of decomposition, an alkyl group with a smaller number of carbon atoms is preferred, and specifically, an alkyl group with 2 carbon atoms is particularly preferred. From the perspective of adhesion, an alkyl group with a larger number of carbon atoms is preferred, and specifically, an alkyl group with 8 carbon atoms is particularly preferred. When R 1 ~R 4 When one of the groups is an alkyl group having 2 to 8 carbon atoms, the remaining group is preferably a hydrogen atom.

[0087] In this embodiment, the aliphatic polycarbonate A may have only one type of structural unit or more than two types. If there are more than two types, their combination and proportion can be appropriately selected according to the purpose. For example, if the aliphatic polycarbonate A has structural unit (1a), the aliphatic polycarbonate A may or may not have structural units other than structural unit (1a). Furthermore, the aliphatic polycarbonate A may have only one type of structural unit (1a) or more than two types of structural units, and the structural units other than structural unit (1a) may be only one type or more than two types.

[0088] In this embodiment, the ratio of the amount of aliphatic polycarbonate A structural unit (1a) to the total amount of structural units is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 97 mol% or more, particularly preferably 99 mol% or more, and may also be 100 mol%.

[0089] Specifically, in this embodiment, the aliphatic polycarbonate A is preferably polybutylene carbonate, a polybutylene carbonate derivative, polydecylene carbonate, or a polydecylene carbonate derivative. The binder B used for firing with this aliphatic polycarbonate A more easily meets the aforementioned physical properties, especially the thermal decomposition temperature and adhesion strength.

[0090] (1-2) Preparation methods of aliphatic polycarbonates The aliphatic polycarbonate A used in this embodiment can be prepared, for example, by a preparation method having the following steps: in the presence of a metal catalyst, controlling the water content to below a specified amount as needed, and polymerizing carbon dioxide (CO2) with a monomer in which the main chain is composed of aliphatic groups. For example, the aliphatic polycarbonate A having structural unit (1a) can be prepared, for example, by a preparation method having the following steps: in the presence of a metal catalyst, controlling the water content to below a specified amount as needed, and polymerizing carbon dioxide with a compound represented by the following general formula (1b) (an olefin oxide (epoxide) or its derivative, hereinafter sometimes abbreviated as "compound (1b)") (for example, see "International Publication No. 2011 / 142259"). In addition, unless otherwise specified, in this specification, "monomer" refers to a compound that polymerizes with carbon dioxide in which the main chain is composed of aliphatic groups. Furthermore, "derivative" refers to a compound in which one or more hydrogen atoms are replaced by groups (substituents) other than hydrogen atoms. Examples of "substituents" here include those related to the aforementioned R... 1 ~R 4 When a substituent is present, it is the same group as the substituent.

[0091] [Chemical Formula 4] In the formula, R 1 R 2 R 3 and R 4 With the R 1 R 2 R 3 and R 4 Same, n is an integer greater than 2.

[0092] In the formula, R 1 ~R 4 R in the aforementioned general formula (1a) 1 ~R 4 Same. In addition, n is an integer greater than 2, which represents the number of structural units (1a) in the aforementioned aliphatic polycarbonate A.

[0093] Preferred compounds (1b) include, for example, butene oxide, 1,2-dimethylethylene oxide, 1,2-epoxybutane, isobutene oxide, 1,2-epoxypentane, 2,3-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyoctane, and 1,2-epoxydecane. Among the above compounds, compound (1b) is more preferably 1,2-epoxybutane, a derivative of 1,2-epoxybutane, 1,2-epoxydecane, or a derivative of 1,2-epoxydecane.

[0094] The monomers used in the polymerization process (e.g., compound (1b) or monomers other than compound (1b)) can be only one or more. If there are more than two, their combination and proportion can be adjusted appropriately according to the purpose.

[0095] Examples of metal catalysts used in the polymerization process include metal-Salen complex catalysts, bimetallic cyanide complex catalysts (DMC catalysts), and organometallic catalysts. Among these catalysts, metal-Salen complex catalysts or DMC catalysts are preferred from the perspective of exhibiting high polymerization activity. Cobalt-Salen complex catalysts are more preferred as metal-Salen complex catalysts, and Zn3(CO[CN]6)2 is more preferred as a DMC catalyst. A single metal catalyst or two or more catalysts may be used simultaneously.

[0096] The amount of metal catalyst used in the polymerization reaction is preferably 0.001 to 10 parts by mass relative to 100 parts by mass of monomer, and particularly preferably 0.01 to 3 parts by mass. This makes the polymerization reaction easier to carry out.

[0097] In the polymerization process, it is also preferable to use a co-catalyst in conjunction with the aforementioned metal catalyst. Examples of co-catalysts include bis(triphenylphosphine)ammonium chloride, 4-dimethylaminopyridine, tetrabutylammonium chloride, tetrabutylammonium bromide, triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,4-diazabicyclo[2.2.2]octane. A single co-catalyst may be used, or two or more may be used simultaneously.

[0098] The amount of co-catalyst used in the polymerization reaction is preferably 0.001 to 20 parts by mass relative to 100 parts by mass of monomer, and particularly preferably 0.01 to 14 parts by mass. This makes the polymerization reaction easier to carry out.

[0099] As long as the target product can be obtained, there are no particular limitations on the method of carrying out the polymerization reaction. For example, the following methods can be listed: adding the aforementioned monomer, metal catalyst, co-catalyst and solvent as needed to an autoclave and mixing them, then pressurizing carbon dioxide into the resulting mixture to carry out the reaction.

[0100] There are no particular limitations on the solvent used in the polymerization reaction as needed, but organic solvents are preferred. Examples of organic solvents include: aliphatic hydrocarbons such as pentane, hexane, octane, decane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloromethane, dichloromethane, chloroform, carbon tetrachloride, 1,1-dichloroethane, chlorobenzene, and bromobenzene; carboxylic acid esters such as ethyl acetate, propyl acetate, butyl acetate, and isobutyl acetate; carbonates such as dimethyl carbonate, diethyl carbonate, propylene carbonate, and 1,2-butenyl carbonate; and lactams such as N-methylpyrrolidone.

[0101] From the perspective of making the polymerization reaction easier to carry out, the amount of solvent used is preferably 50 to 10,000 parts by mass relative to 100 parts by mass of monomer used.

[0102] The pressure at which carbon dioxide is introduced during the polymerization reaction is not particularly limited, but is preferably 0.1 to 20 MPa, more preferably 0.1 to 10 MPa, and even more preferably 0.1 to 5 MPa. By keeping the pressure at which carbon dioxide is introduced above the lower limit mentioned above, the polymerization reaction becomes easier to carry out. Furthermore, by keeping the pressure at which carbon dioxide is introduced below the upper limit mentioned above, the excessive use of carbon dioxide is suppressed, and economic efficiency is improved.

[0103] When carrying out polymerization reactions, it is preferable that the water content in the reaction system is less than 5 mol% relative to the amount (moles) of the metal catalyst used.

[0104] The reaction temperature during polymerization is not particularly limited, but is preferably 20°C or higher, more preferably 40°C or higher. Furthermore, the reaction temperature during polymerization is preferably 100°C or lower, more preferably 80°C or lower. By setting the reaction temperature above the aforementioned lower limit, the polymerization reaction ends in a shorter time. Furthermore, by setting the reaction temperature below the aforementioned upper limit, side reactions are suppressed, and the yield of aliphatic polycarbonate is increased.

[0105] The reaction time of the polymerization reaction can be adjusted appropriately according to the reaction temperature, but it is preferably 2 to 40 hours.

[0106] After the polymerization reaction is complete, known post-processing operations can be performed as needed, and then aliphatic polycarbonate A, the target product, can be obtained using known methods. Furthermore, the obtained aliphatic polycarbonate A can be purified as required.

[0107] Carbon dioxide is a contributor to global warming, and various industrial sectors emit it daily, prompting efforts to reduce emissions globally. The aforementioned preparation method, using carbon dioxide as a raw material, is excellent in this regard because it can fix carbon dioxide and expands the range of available carbon resources.

[0108] The aliphatic polycarbonate A contained in the binder B used for firing in this embodiment may be only one type or two or more types. In the case of two or more types, their combination and proportion can be arbitrarily selected according to the purpose.

[0109] (2) Other ingredients Provided that it does not impede the required low-temperature decomposition, adhesion, and firing performance, the binder B for firing in this embodiment may contain various additives in addition to aliphatic polycarbonate A, such as acid-producing / alkali-producing agents, sensitizers, adhesion-improving agents, etc., that promote the decomposition of aliphatic polycarbonate A.

[0110] 2. Purpose The binder B used for firing in this embodiment can be used for firing various metals or ceramics, and is preferably used for firing metal oxide precursors (manufacturing metal oxide sintered bodies). As mentioned above, metal oxide precursors refer to substances that can form metal oxides when fired in an oxygen atmosphere. Examples of preferred precursors include: elemental metals or alloys such as gold, silver, copper, aluminum, nickel, and tungsten; metal carbides such as silicon carbide; and metal nitrides such as silicon nitride and aluminum nitride.

[0111] Furthermore, the binder B used for sintering in this embodiment is preferably used for forming a sintered body of a metal oxide precursor or a sintered foil of a metal oxide precursor on a substrate, or for forming a sintered body of a metal oxide or a sintered foil of a metal oxide on a substrate. As the substrate, metal oxide precursor components (including the concept of metal oxide precursor foil) are preferably listed, and metal elemental components such as copper and aluminum are particularly preferred.

[0112] As mentioned above, because the binder B used for sintering in this embodiment has high adhesion to metals, it is possible to easily and efficiently prepare composites of metal components and metal sintered bodies or metal oxide sintered bodies with high precision. Examples of such composites include composites of aluminum components and aluminum sintered bodies, composites of copper components and alumina sintered bodies, composites of alumina components and copper sintered bodies, and composites of alumina components and tungsten sintered bodies.

[0113] Composites of aluminum components and sintered aluminum bodies can be suitably used as electrode materials for aluminum electrolytic capacitors, for example. In this case, the aluminum component is preferably an aluminum substrate, particularly an aluminum substrate made of aluminum foil (aluminum foil substrate). Furthermore, as an electrode material for aluminum electrolytic capacitors, a material in which sintered aluminum bodies are formed on one or both sides of the aluminum substrate is preferred.

[0114] The composite of copper components and alumina sintered bodies can be suitably used as a substrate for power modules, for example. In this case, the copper component is preferably a copper substrate, particularly a copper substrate made of copper foil (copper foil substrate). Furthermore, as a substrate for power modules, it is preferable to have an alumina sintered body formed on one or both sides of the copper substrate.

[0115] The composite of alumina components and copper sintered bodies can be suitably used as components for power semiconductors, for example. In this case, the alumina component is preferably an alumina substrate. Furthermore, as a component for power semiconductors, it is preferable to have a copper sintered body formed on one or both sides of the alumina substrate.

[0116] [Paste composition for firing] The paste composition for firing in this embodiment (hereinafter sometimes referred to as "paste composition C for firing") contains metal oxide precursor powder and the binder B for firing in the aforementioned embodiment, and preferably further contains a solvent.

[0117] Preferred precursor powders for metal oxides include gold powder, silver powder, copper powder, aluminum powder, nickel powder, tungsten powder, silicon carbide powder, silicon nitride powder, and aluminum nitride powder. Metal powders can be composed of the metal itself or of an alloy of that metal.

[0118] The average particle size of the metal oxide precursor powder is preferably 0.3 to 15 μm, particularly preferably 0.8 to 10 μm, and even more preferably 1 to 6 μm. Therefore, as a sintered body / metal oxide precursor, it can perform the desired function well. Furthermore, in this specification, the average particle size of the metal oxide precursor powder can be measured not only by laser diffraction scattering to determine the individual powder particles, but also by observing the cross-section of the sintered body using a scanning electron microscope.

[0119] The content of metal oxide precursor powder in the paste composition C used for sintering is preferably 30 to 79.5% by mass, and particularly preferably 40 to 70% by mass. Thus, as a sintered body of metal oxide precursor, it can perform the required function while ensuring good adhesion to the substrate.

[0120] The content of binder B for sintering in the paste composition C for sintering is preferably 0.5 to 35% by mass, and particularly preferably 0.75 to 10% by mass. This results in excellent adhesion to the substrate, and simultaneously, as a sintered body containing a metal oxide precursor, it can perform the desired functions.

[0121] The solvents that can be contained in the paste composition C used for calcination are not particularly limited. Examples 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 hydrocarbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate, and butyl acetate; alcohols such as isopropanol, butanol, cyclohexanol, and 1-decanol; cellosolvers such as methyl cellosolvers and ethyl cellosolvers; 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); and cellosolve acetates. Acetate-based solvents; sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide and dimethylacetamide, etc. These solvents can be used alone or in combination of two or more.

[0122] The solvent content in the paste composition C used for firing is preferably 20-69.5% by mass, and particularly preferably 30-55% by mass. This results in excellent coatability and formability, while ensuring good adhesion to the substrate.

[0123] The paste composition C used for sintering may contain other components such as sintering aids and surfactants as needed. Sintering aids are not particularly limited; for example, fluorides such as aluminum fluoride, potassium fluoride, and calcium fluoride can be used. Surfactants are not particularly limited; for example, betaine-based, sulfobetaine-based, and alkylobetaine-based surfactants can be used.

[0124] To prepare the paste composition C for sintering, the metal oxide precursor powder, the binder B for sintering, the solvent, and other ingredients as needed are mixed and kneaded.

[0125] The paste composition C for firing is preferably adjusted to a concentration / viscosity suitable for coating or molding by adjusting the amount of solvent. For example, in the case of coating, it is preferable to dilute with a solvent to make the solids concentration 10-60% by mass.

[0126] [Sintered body] A sintered body according to one embodiment of the present invention is obtained by firing the paste composition C for firing as described in the aforementioned embodiment. The sintered body can be a metal oxide precursor sintered body or a metal oxide sintered body.

[0127] The shape of the sintered body in this embodiment is not particularly limited, and it can be made into desired shapes such as layered, plate-like, or block-like forms. Furthermore, by using a paste composition C for sintering containing a binder B for sintering, the sintered body of this embodiment has high adhesion to metal, and therefore is preferably made into a form that is joined to a metal component.

[0128] When the sintered body of this embodiment is formed in a layered manner, the thickness of the sintered body is preferably 10 to 500 μm, particularly preferably 20 to 400 μm, and even more preferably 30 to 300 μm.

[0129] When manufacturing the sintered body according to the embodiment, firstly, the paste composition C for firing is formed into the desired shape. For example, when manufacturing a layered sintered body, it is preferable to apply the paste composition C for firing to the desired object, such as a metal component. Furthermore, when manufacturing a plate-shaped, block-shaped, or other sintered body, it is preferable to fill the desired mold with the paste composition C for firing and then shape it.

[0130] In any case, it is preferable to properly dry the paste composition C for firing after coating / forming. Examples of drying conditions include drying at a temperature of 20-300°C for 1-30 minutes.

[0131] Examples of coating methods for the paste composition C used in firing include rod coating, knife coating, doctor blade coating, screen printing, roller coating, blade coating, mold coating, gravure coating, curtain coating, and spray coating.

[0132] When the paste composition C for firing is applied to a metal component, the aliphatic polycarbonate A contained in the paste composition C results in excellent adhesion of the layer of paste composition C to the metal component. Therefore, the operability becomes very good, and high-precision products can be manufactured with a good yield.

[0133] Next, the paste composition C, which has been formed into the desired shape, is fired to obtain a sintered body. The firing method is not particularly limited; for example, heating in a furnace can be used.

[0134] The firing temperature is preferably a temperature greater than half (absolute temperature) to less than the melting point of the material to be fired. Here, the binder B used for firing undergoes thermal decomposition, and the metal oxide precursor powder is sintered and solidified, thereby obtaining a sintered body. In this embodiment, the paste composition C used for firing uses a binder B containing aliphatic polycarbonate A, which has excellent low-temperature decomposition properties, and therefore can be fired at a lower temperature as described above. Furthermore, when laminated onto a metal component, by setting the lower limit of the firing temperature to the aforementioned value, the adhesion to the metal component becomes more excellent. Furthermore, by setting the upper limit of the firing temperature to the aforementioned value, a sintered body with a good morphology is easily obtained.

[0135] The sintering time is preferably 0.1 to 48 hours, particularly preferably 1 to 36 hours, and even more preferably 5 to 24 hours. This ensures that the metal oxide precursor powder is fully sintered, resulting in a well-formed sintered body.

[0136] The sintering atmosphere is preferably an oxygen-free atmosphere. An oxygen-free atmosphere can be an atmosphere composed of a single gas, an atmosphere composed of a mixture of gases, or a vacuum atmosphere. Examples of single gases include nitrogen, argon, helium, ammonia, and formaldehyde. Examples of mixtures include forming gases; for example, nitrogen mixed with less than 5% by volume of hydrogen can be considered a forming gas.

[0137] When forming a sintered body containing a metal oxide precursor, an oxygen-free atmosphere, and particularly a nitrogen atmosphere, is preferred from the perspective of preventing oxidation of the metal oxide precursor powder. The aliphatic polycarbonate A contained in the paste composition C used for sintering exhibits low-temperature decomposition properties even in an oxygen-free atmosphere. Therefore, in the sintered body of the embodiment, oxidation of the metal can be prevented and sintering can be performed at a lower temperature.

[0138] From the perspective of preventing metal oxidation, the oxygen concentration in the oxygen-free atmosphere is preferably 5% by volume or less, more preferably 3% by volume or less, particularly preferably 0.5% by volume or less, and even more preferably 0.1% by volume or less.

[0139] The pressure conditions of the sintering atmosphere can be any of atmospheric pressure, reduced pressure, or increased pressure.

[0140] As mentioned earlier, the main byproducts of aliphatic polycarbonate A during sintering are cyclic carbonates. Therefore, virtually no carbon dioxide is emitted during sintering, and no solid carbon compounds from the binder remain in the sintered body of the embodiment. Furthermore, the cyclic carbonates produced can be recycled into solvents or electrolytes for lithium-ion batteries.

[0141] [Sintered composite] In one embodiment of the present invention, the sintering composite may be a sintering composite in which a metal sintered body is formed on a substrate, or it may be a sintering composite in which a metal oxide sintered body is formed on a substrate. Preferably, a metal component is provided as the substrate, and this metal component may be a metal foil. Furthermore, the aforementioned metal sintered body may be a metal sintered foil, and the aforementioned metal oxide sintered body may be a metal oxide sintered foil.

[0142] Examples of sintering composites used in this embodiment include composites of aluminum components (aluminum foil substrate) and aluminum sintered bodies, composites of copper components (copper foil substrate) and alumina sintered bodies, and composites of alumina components and copper sintered bodies. The uses of these composites are as described above.

[0143] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are also intended to include all design changes and equivalent technical solutions that fall within the scope of the present invention.

[0144] Furthermore, in this specification, when "X~Y" (where X and Y are arbitrary numbers) is used, unless otherwise specified, it includes the meaning of "X or more and Y or less," and also includes the meaning of "preferably greater than X" or "preferably less than Y." Additionally, when "X or more" (where X is any number) is used, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "Y or less" (where Y is any number) is used, unless otherwise specified, it includes the meaning of "preferably less than Y." Example

[0145] The present invention will now be described in further detail by way of examples, but the present invention is not limited in any way by the examples described below.

[0146] [Manufacturing Example 1] (Synthesis of Polymerization Catalyst - 1) (R,R)-N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-cyclohexanediamine cobalt(II) and pentafluorobenzoic acid were weighed in a molar ratio of 1:1.1 and placed in a flask. Dehydrated toluene was added. The flask was shielded from light using aluminum foil and allowed to react at room temperature for 20 hours. The chemical reaction equation is shown below. After the reaction was complete, the solvent was removed under reduced pressure, and the mixture was washed several times with excess hexane. Then, it was dried under vacuum at room temperature to obtain the cobalt-Salen complex.

[0147] [Chemical Formula 5]

[0148] [Manufacturing Example 2] (Synthesis of Polymerization Catalyst - 2) 1.33 g of potassium hexacyanocobalamin(III) (K3[Co(CN)6]) was dissolved in 20 mL of deionized water and added dropwise over 45 minutes to a vigorously stirred 50 °C zinc chloride solution (a solution obtained by dissolving 11.42 g of ZnCl2 in a mixture of 60 mL of deionized water and 30 mL of tert-butanol). The mixture was then vigorously stirred for 60 minutes. The resulting white suspension was centrifuged at 5000 rpm to separate the white solid. The separated white solid was then resuspended in a solution of tert-butanol and deionized water (by volume, tert-butanol:deionized water = 5:5) with vigorous stirring for 30 minutes. Then, the amount of tert-butanol relative to water was slowly increased (by volume, the tert-butanol:deionized water ratio was changed from 6:4 to 7:3, 8:2, and 9:1), and the separation and resuspension based on centrifugation were repeated several times. Finally, the white solid was resuspended in tert-butanol and then separated by centrifugation. It was then dried to a specified mass at 50°C under vacuum to obtain Zn3(C0[CN]6)2 as a DMC catalyst.

[0149] [Example 1] 100 parts by mass of 1,2-epoxybutane as a raw material monomer, 0.6 parts by mass of the cobalt-Salen complex obtained in Preparation Example 1 as a catalyst, and 0.4 parts by mass of bis(triphenylphosphine)ammonium chloride as a co-catalyst were dissolved in 100 parts by mass of ethyl acetate to obtain a mixture (solid component concentration: 50% by mass).

[0150] The system was pre-purged with nitrogen atmosphere in a 4L autoclave equipped with a stirrer, gas inlet pipe, and thermometer, and then the above mixture was added. Next, carbon dioxide gas was added while stirring the resulting mixture until the pressure in the reaction system reached 2MPa. Then, the temperature was raised to 30°C, and the polymerization reaction was carried out for 18 hours while replenishing the carbon dioxide consumed in the reaction. After the reaction was completed, the autoclave was cooled and depressurized, and the contents were diluted with ethyl acetate. The catalyst was removed by reprecipitation purification.

[0151] The obtained ethyl acetate solution was dried to obtain the generated aliphatic polycarbonate. This aliphatic polycarbonate is polybutylene carbonate (PBC). This polybutylene carbonate (PBC) is used as a binder for sintering in this example. Furthermore, the hydrocarbon groups in the side chains of the polybutylene carbonate have 2 carbon atoms.

[0152] [Example 2] 100 parts by mass of 1,2-epoxybutane, used as a raw material monomer, and 0.5 parts by mass of DMC catalyst, used as the catalyst obtained in Manufacturing Example 2, were dissolved in 100 parts by mass of ethyl acetate to obtain a mixture (solid content concentration: 50% by mass). Using the obtained mixture, polybutylene carbonate (PBC) was prepared in the same manner as in Example 1. This polybutylene carbonate (PBC) was used as the binder for firing in this example.

[0153] [Example 3] 100 parts by mass of 1,2-epoxyhexane, which is used as a raw material monomer, and 0.1 parts by mass of the cobalt-Salen complex, which is used as a catalyst obtained in Manufacturing Example 1, are dissolved in 100 parts by mass of toluene to obtain a mixture (solid component concentration: 50% by mass).

[0154] The system was pre-purged with nitrogen atmosphere in a 4L autoclave equipped with a stirrer, gas inlet pipe, and thermometer, and then the above mixture was added. Next, carbon dioxide gas was added while stirring the resulting mixture until the pressure in the reaction system reached 2MPa. Then, the temperature was raised to 30°C, and the polymerization reaction was carried out for 18 hours while replenishing the carbon dioxide consumed in the reaction. After the reaction was completed, the autoclave was cooled and depressurized, and the contents were diluted with ethyl acetate. The catalyst was removed by reprecipitation purification.

[0155] The obtained toluene solution was dried to obtain the generated aliphatic polycarbonate. This aliphatic polycarbonate is polyhexanediol carbonate (PHC). This polyhexanediol carbonate (PHC) is used as a binder for sintering in this example. Furthermore, the hydrocarbon groups in the side chains of the polyhexanediol carbonate have 4 carbon atoms.

[0156] [Comparative Example 1] Except that propylene oxide was used as the raw material monomer instead of 1,2-epoxybutane, an aliphatic polycarbonate was prepared in the same manner as in Example 1. This aliphatic polycarbonate was polypropylene carbonate (PPC). This polypropylene carbonate (PPC) was used as the binder for firing in this example. Furthermore, the hydrocarbon groups in the side chains of the polypropylene carbonate had only one carbon atom.

[0157] [Comparative Example 2] 100 parts by mass of 1,2-epoxydecane, which is used as a raw material monomer, and 0.1 parts by mass of the DMC catalyst obtained in Manufacturing Example 2 were dissolved in 100 parts by mass of ethyl acetate to obtain a mixture (solid component concentration: 50% by mass).

[0158] The system was pre-primed with nitrogen atmosphere in a 4L autoclave equipped with a stirrer, gas inlet pipe, and thermometer, and then the above mixture was added. Next, carbon dioxide gas was added while stirring the resulting mixture until the pressure in the reaction system 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 in the reaction. After the reaction was completed, the autoclave was cooled and depressurized, and the contents were diluted with ethyl acetate. The catalyst was removed by reprecipitation purification.

[0159] The obtained ethyl acetate solution was dried to obtain the generated aliphatic polycarbonate. This aliphatic polycarbonate is polydecanediol carbonate (PDC). This polydecanediol carbonate (PDC) was used as a binder for firing in this example. In addition, the hydrocarbon groups in the side chains of the polydecanediol carbonate have 8 carbon atoms.

[0160] [Comparative Example 3] 100 parts by weight of 1,2-epoxyhexane (as a raw material monomer) and 0.1 parts by weight of DMC catalyst (as the catalyst obtained in Manufacturing Example 2) were dissolved in 100 parts by weight of toluene to obtain a mixture (solid content concentration: 50% by weight). Polyhexanediol carbonate (PHC) was prepared using the obtained mixture in the same manner as in Example 3. This polyhexanediol carbonate (PHC) was used as the binder for firing in this example.

[0161] [Experimental Example 1] (Determination of Molecular Weight) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the binders used in the examples and comparative examples for firing were determined using a gel permeation chromatography apparatus (manufactured by TOSOH CORPORATION, product name "HLC-8320") under the following conditions, and were determined by conversion to standard polystyrene. Furthermore, the molecular weight distribution (PDI = Mw / Mn) was calculated based on the obtained weight-average molecular weight (Mw) and number-average molecular weight (Mn). The results are shown in Table 1.

[0162] <GPC Measurement Conditions> • Chromatographic column: A chromatographic column composed of “TSK guard column SuperH-H”, “TSK gel SuperHM-H”, “TSK gel SuperHM-H”, and “TSK gel SuperH2000” (all manufactured by TOSOH CORPORATION) connected in sequence. • Column temperature: 40℃ • Developing agent: Tetrahydrofuran (binder concentration 1% by mass) Injection volume: 20 μl • Flow rate: 0.6 mL / min • Detector: Differential refractometer Standard sample: Polystyrene

[0163] [Experimental Example 2] (Determination of Glass Transition Temperature) The glass transition temperature (Tg) of the binders used for firing in the examples and comparative examples was determined by differential scanning calorimetry (DSC) using a product named "DSC Q2000" manufactured by TA Instruments Japan Inc. Specifically, using an aluminum crucible as the container, the temperature was increased from -70°C to 150°C at a rate of 10.0°C / min under a nitrogen atmosphere, held for 5 minutes, then decreased 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.

[0164] [Experimental Example 3] (Determination of Thermal Decomposition Temperature) For the binders used in the examples and comparative examples for firing, the thermal decomposition temperature was determined using a thermogravimetric analyzer (TGA; manufactured by Shimadzu Corporation, product name "DTG-60") under the following conditions. Furthermore, the following thermal decomposition temperatures were obtained: 5% thermal decomposition temperature in nitrogen (Td5), 10% thermal decomposition temperature in nitrogen (Td10), 50% thermal decomposition temperature in nitrogen (Td50), 99% thermal decomposition temperature in nitrogen (Td99), 5% thermal decomposition temperature in air (Td5), 10% thermal decomposition temperature in air (Td10), 50% thermal decomposition temperature in air (Td50), and 99% thermal decomposition temperature in air (Td99). The results are shown in Table 1.

[0165] <TGA Measurement Conditions> Heating rate: 10℃ / min Sample size: 20~30mg Measurement temperature range: 40℃~550℃ Measurement atmosphere: nitrogen / air Pressure measured: Atmospheric pressure In addition, the oxygen concentration in the nitrogen atmosphere is below 0.1%.

[0166] [Experimental Example 4] (Evaluation of Residual Carbon Compounds - 1) The aluminum crucible used in Example 3 after TGA determination under nitrogen atmosphere was visually inspected to confirm the presence of any residual carbon compounds. Furthermore, the residual carbon compounds were evaluated according to the following criteria. The results are shown in Table 2. A…The bottom of the aluminum crucible is exposed, and a metallic luster can be confirmed (=no residual components). F…The state where residual combustion ash remains and the bottom of the aluminum crucible is not visible.

[0167] [Experimental Example 5] (Evaluation of Residual Carbon Compounds - 2) Two glass plates (manufactured by AGC Inc., product name "Float Flat Glass FL3", 150mm long × 70mm wide × 3mm thick) were used to sandwich the binder for firing in the examples and comparative examples. A screw-type hot press (manufactured by NPa SYSTEM CO.,LTD., product name "N4046-00") was used at 150°C and 200N for 5 minutes to form a 100μm thick binder layer between the glass plates, which was then cooled to room temperature. Next, the laminate was placed on a heating plate at 300°C and heated for 2 minutes. The condition of the binder between the glass plates was then checked. Residual carbon compounds were evaluated according to the following criteria. The results are shown in Table 2. Note that "Evaluation of Residual Carbon Compounds-2" in Test Example 5 was conducted under more stringent conditions than "Evaluation of Residual Carbon Compounds-1" in Test Example 4. A… The adhesive decomposes, and the distance between the glass plates is less than 1 μm. F…The adhesive remains undecomposed or its decomposition products remain between the glass plates, and the distance between the glass plates is more than 1 μm.

[0168] [Experimental Example 6] (Determination of Ether Bond Ratio) To achieve a 3% by mass concentration of the binder used for firing in the examples and comparative examples, it was dissolved in deuterated chloroform containing tetramethylsilane (TMS) as an internal standard. 1 The sample was analyzed by 1H-NMR. The following conditions were used for this sample. 1 ¹H-NMR determination was used to calculate the stoichiometry (100 mol%) of ether bonds relative to carbonate bonds and the total ether bond content in each polymer. Specifically, the integral value of 4.7–5.2 ppm was used as the stoichiometry of carbonate bonds. 1 H, taking the integral value of 3.2~3.9ppm as the ether bond 3 H is calculated using the following formula. The results are shown in Table 2. Ether bond content (%) = ether bonds / 3 / (carbonate bonds + ether bonds / 3)

[0169] < 1 H-NMR measurement conditions > Device: Manufactured by Bruker Corporation, product name "AV-500" 1 H-NMR resonance frequency: 500MHz Probe: 5mm Solution probe Deuterated solvent: Deuterated chloroform (CDCl3) Internal standard material: Tetramethylsilane (TMS) Sample size: 20~50mg Measurement temperature: 25℃ Total number of times: 16

[0170] [Experimental Example 7] (Determination of Adhesion Force - 1) The binders used for firing in Examples 1 and 2 (Comparative Example 1) were dissolved in toluene to prepare a coating solution with a solid content concentration of 30% by mass. The binders used for firing in Comparative Examples 2-4 were dissolved in ethyl acetate to prepare a coating solution with a solid content concentration of 30% by mass.

[0171] The above-mentioned coating liquid was applied to an aluminum plate (A1050P, 0.5 mm thick) as the substrate using an applicator, and then heated and dried at 100°C for 1 minute. This resulted in the formation of a 20 μm thick and 25 mm wide layer of adhesive for firing on the aluminum plate.

[0172] A 25mm wide polyester adhesive tape (manufactured by Nitto Denko Corporation, product name "No. 31B") was applied to the layer of adhesive for firing on the aluminum plate, and a 2kg roller was rolled back and forth once to ensure adhesion. The sample was then left to stand at 23°C and 50%RH for 30 minutes.

[0173] The above samples were fixed in a tensile testing machine (manufactured by ORIENTEC CO., LTD., product name "TENSILON") and, in an environment of 23°C and 50%RH (relative humidity), according to JIS Z0237:2000, the layer of adhesive used for firing was peeled from the aluminum plate at a tensile speed of 300 mm / min in a 180° direction. The value measured at this time (N / 25 mm) was taken as the adhesion force. The results are shown in Table 2.

[0174] [Experimental Example 8] (Determination of Adhesion Force - 2) For Examples 1, 2 and Comparative Example 1, a coating liquid for a paste composition for firing was prepared by mixing 95 parts by weight of alumina powder (manufactured by Sumika Alchem ​​Co., Ltd., product name "AdvancedAlumina AA-2", median particle size of 2.2 μm (determined by laser diffraction scattering)), 5 parts by weight of the binder for firing in Examples 1, 2 and Comparative Example 1, and 54 parts by weight of propylene glycol monomethyl ether acetate (PGMEA) as a solvent for 24 hours.

[0175] For Comparative Examples 2-4, a coating liquid for a paste composition for firing was prepared by mixing 95 parts by weight of alumina powder (manufactured by AS ONE Corporation, product name "ZB-5"), 5 parts by weight of binder for firing from Comparative Examples 2-4, and 43 parts by weight of a mixed solvent of toluene:n-butanol = 80:20 (mass ratio) for 24 hours using zirconia beads (manufactured by AS ONE Corporation, product name "ZB-5"), alumina powder (manufactured by Sumika Alchem ​​Co., Ltd., product name "Advanced AluminaAA-2"), median particle size of 2.2 μm (determined by laser diffraction scattering method), and 43 parts by weight of a mixed solvent of toluene:n-butanol = 80:20 (mass ratio) for 24 hours.

[0176] For Examples 1 and 2 and Comparative Example 1, the above-mentioned coating liquid was applied to aluminum (Al) foil (20 μm thick) and copper (Cu) foil (11 μm thick) as metal foils using a coater, and then heated and dried at 120°C for 5 minutes. This resulted in the formation of a paste composition layer with a thickness of 70 μm and a width of 25 mm on the metal foils for firing.

[0177] For Comparative Examples 2-4, the above-mentioned coating liquid was applied to aluminum foil (20 μm thick) and copper foil (11 μm thick) as metal foils using a coater, and then heated and dried at 100°C for 5 minutes. As a result, a layer of paste composition for firing with a thickness of 70 μm and a width of 25 mm was formed on the metal foils.

[0178] The adhesive side of the adhesive tape (manufactured by LINTEC Corporation, product name "PET50(A) PL Shin 8K") was adhered to a layer of the paste composition for firing on the aforementioned metal foil. This laminate was shaped to a width of 25 mm and a length of 100 mm and attached to a glass plate using double-sided tape. It was then left to stand at 23°C and 50% RH for 12 hours as a sample.

[0179] The above samples were fixed in a tensile testing machine (manufactured by ORIENTEC CO., LTD., product name "TENSILON"), and peeled from the metal foil in a 180° direction at a tensile speed of 300 mm / min under conditions of 23°C and 50% RH (relative humidity), according to JIS Z0237:2000. The value measured at this time (N / 25 mm) was taken as the adhesion force. The results are shown in Table 2.

[0180] Furthermore, since the layers of the paste composition for firing in the embodiment did not undergo cohesive failure upon peeling, it can be determined that the binder for firing in the embodiment has high adhesion to alumina powder (metal oxide precursor powder).

[0181] [Experimental Example 9] (Evaluation of Paste Softness) With the aluminum foil as the inside, the laminate of the aluminum foil prepared in Example 8 and the layer of the paste composition for firing was wound onto rods with diameters of 1 inch and 3 inches. The presence of cracks in the layer of the paste composition for firing was visually assessed. Furthermore, the softness of the paste was evaluated according to the following criteria. The results are shown in Table 2. A… did not crack when wound around a 1-inch rod. F+… produced cracks when wound onto a 1-inch rod, but did not produce cracks when wound onto a 3-inch rod. F-… cracks occurred when wound onto both 1-inch and 3-inch rods.

[0182] [Experimental Example 10] (Evaluation of Slurry Processability) Using a coater, the coating liquid (slurry) of the paste composition for firing prepared in Test Example 8 was applied onto aluminum foil to form a coating film. The condition of the coating film was visually confirmed, and the processability of the slurry was evaluated according to the following criteria. The results are shown in Table 2. A…coating surface is smooth F…coating surface roughness

[0183] [Experimental Example 11] (Determination of Storage Modulus) The binders used for firing in the examples and comparative examples were formed into cylinders with a diameter of 8 mm and a thickness of 1 mm, and these were used as samples. In a viscoelasticity measuring apparatus (manufactured by Anton Paar, apparatus name "MCR300"), using an 8 mm diameter parallel plate as the measuring fixture, the storage modulus (MPa) of the above samples at various temperatures was measured by torsional shear method under the following conditions: initial test temperature -20°C, final test temperature 150°C, heating rate 3°C / min, shear strain 0.05%, and frequency 1 Hz. The storage modulus (MPa) at 23°C was obtained from this measurement. The results are shown in Table 2.

[0184] [Experimental Example 12] (Tension Test) The binders used for firing in the examples and comparative examples were formed into rectangles 10 mm wide × 30 mm long × 0.5 mm thick, which were used as samples. The samples were mounted on a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph AG-Xplus") with a chuck spacing of 10 mm and stretched at 23°C and a tensile speed of 200 mm / min until fracture. The elongation at break (%) was measured, and the stress at each elongation was also measured to obtain the maximum stress (MPa). The results are shown in Table 2.

[0185] [Table 1]

[0186] [Table 2]

[0187] As shown in Tables 1 and 2, the binder prepared in the examples decomposes at a lower temperature, thus enabling firing at a lower temperature. Furthermore, the binder prepared in the examples exhibits high adhesion to both the metal oxide precursor powder and the metal. Moreover, the binder prepared in the examples demonstrates excellent residual carbon suppression even under harsh conditions, and excellent slurry processability. Additionally, the binder prepared in the examples has a low glass transition temperature, low storage modulus at room temperature, high elongation at break, and low maximum stress. Because the paste composition containing the metal oxide precursor powder is soft, cracks do not occur even when wound onto small-diameter rods, thus increasing the design freedom for the sintered body shape. Industrial applicability

[0188] The binder for sintering of the present invention is suitable for manufacturing, for example, sintered bodies of metal oxide precursors or sintered bodies of metal oxides, or composites of these sintered bodies with metal substrates.

Claims

1. A binder for firing, comprising an aliphatic polycarbonate having a carbonate structure in its main chain and hydrocarbon groups having 2 to 8 carbon atoms in its side chains, characterized in that... The aliphatic polycarbonate has a weight-average molecular weight of 50,000 or more and 170,000 or less.

2. The binder for firing according to claim 1, characterized in that, In an atmosphere with atmospheric pressure and an oxygen concentration of less than 5%, the 50% thermal decomposition temperature of the binder used for firing is above 255°C and below 300°C.

3. The binder for firing according to claim 1, characterized in that, In an atmosphere with atmospheric pressure and an oxygen concentration of less than 5%, the 99% thermal decomposition temperature of the binder used for firing is below 400°C.

4. The binder for firing according to claim 1, characterized in that, When peeling the layer of the sintering adhesive, which has a thickness of 20 μm, from an aluminum plate at a peel angle of 180° and a peel speed of 300 mm / min, the adhesion force measured is 0.3 N / 25 mm or more.

5. The binder for firing according to claim 1, characterized in that, The hydrocarbon groups with 2 to 8 carbon atoms are straight-chain hydrocarbon groups.

6. The binder for firing according to claim 1, characterized in that, The aliphatic polycarbonate has the structural unit represented by the following general formula (1a). [Chemical Formula 1] ， In general formula (1a), R 1 R 2 R 3 and R 4 Each is independently a hydrogen atom or a hydrocarbon group, and at least one of them is a hydrocarbon group with 2 to 8 carbon atoms.

7. The binder for firing according to claim 1, characterized in that, The binder used for sintering is used to form a sintered body of metal oxide precursor.

8. The binder for firing according to claim 1, characterized in that, The binder used for firing is used to form a sintered metal oxide body.

9. The binder for firing according to claim 1, characterized in that, The binder used for sintering is used to form a sintered foil of a metal oxide precursor on a substrate.

10. The binder for firing according to claim 1, characterized in that, The binder used for firing is used to form a sintered metal oxide foil on a substrate.

11. The binder for firing according to claim 1, characterized in that, The binder used for firing has a storage modulus of 1.0 MPa or more and 50 MPa or less at 23°C.

12. The binder for firing according to claim 1, characterized in that, The glass transition temperature (Tg) of the binder used for firing is above -15°C and below 25°C.

13. The binder for firing according to claim 1, characterized in that, The binder used for firing is formed to have a thickness of 0.5 mm and a width of 10 mm, and when stretched at a measurement temperature of 23°C, a measurement length of 10 mm, and a stretching speed of 200 mm / min, the elongation at break is 100% or more.

14. The binder for firing according to claim 1, characterized in that, The binder used for firing is formed to be 0.5 mm thick and 10 mm wide, and stretched at a test temperature of 23°C, a test length of 10 mm, and a stretching speed of 200 mm / min until the maximum stress at the elongation at break is less than 10 MPa.

15. A paste composition for firing, comprising a metal oxide precursor powder and a binder for firing according to any one of claims 1 to 14.

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