Composite structure, laminated ceramic electronic component precursor, method for manufacturing laminated ceramic electronic component precursor, and method for manufacturing laminated ceramic electronic component

Abstract

Provided are: a composite structure containing a structure including an aliphatic polycarbonate and inorganic particles, and the structure including an aliphatic polycarbonate and inorganic particles and another structure contacted therewith are not easily peeled off at the interface of both by external force; a laminated ceramic electronic component precursor containing the above composite structure; a method for manufacturing the above laminated ceramic electronic component precursor; and a method for manufacturing a laminated ceramic electronic component including the method for manufacturing the above laminated ceramic electronic component precursor. In the composite structure containing a structure including an aliphatic polycarbonate and inorganic particles, a first structure including an aliphatic polycarbonate and first inorganic particles is compounded with a second structure including a branched polymer and second inorganic particles, and as the branched polymer, a polymer having a main chain formed of a cellulose-based polymer and a side chain formed of an aliphatic polycarbonate or an aliphatic polyester is used.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite structure body containing a structure body including an aliphatic polycarbonate and inorganic particles, a laminated ceramic electronic component precursor including the above composite structure body, a manufacturing method of the above laminated ceramic electronic component precursor, and a manufacturing method of a laminated ceramic electronic component including the manufacturing method of the above laminated ceramic electronic component precursor. BACKGROUND

[0002] In the past, a structure body in which inorganic particles are dispersed in an aliphatic polycarbonate has been used for various purposes. Such a structure body is complexed with a structure body including a resin other than an aliphatic polycarbonate and inorganic particles for various purposes, and is used in the form of a composite structure body.

[0003] For example, in Patent Literature 1, it is proposed that, in a sintering ceramic molding composition, an aliphatic polycarbonate excellent in thermal decomposition is used as a binder for dispersing ceramic particles.

[0004] In addition, in Patent Literature 2, it is proposed that, in a conductive paste for forming an internal electrode layer formed on a dielectric layer of a sintered ceramic in a laminated ceramic capacitor, ethyl cellulose is used as a component for dispersing conductive powders such as metal particles. The ethyl cellulose imparts good printing properties, excellent dispersion stability of conductive powders to the conductive paste described in Patent Literature 2.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-020916

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 2018-168238 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] For example, if a sheet-shaped layer formed of the sintering ceramic molding composition described in Patent Literature 1 is laminated and complexed with a sheet-shaped layer formed of the conductive paste described in Patent Literature 2, a laminate of a laminated ceramic electronic component is obtained by firing.

[0011] The laminate is cut by a method such as press cutting so as to match the size of the laminated ceramic electronic component to be manufactured, and is often supplied to firing in a state of being divided into small pieces.

[0012] However, the aliphatic polyester contained in the sintering ceramic forming composition is not necessarily excellent in adhesion to other kinds of resin. Therefore, if an external force is applied to a laminate obtained by stacking a sheet-shaped layer formed of the sintering ceramic forming composition described in Patent Document 1 and a sheet-shaped layer formed of the conductive paste described in Patent Document 2, and cutting is performed, there is a problem that peeling between the layers is easily generated due to insufficient adhesion between the layers.

[0013] The present application has been achieved in view of the above problems, and aims to provide a composite structure containing a structure including an aliphatic polycarbonate and inorganic particles, and the structure including an aliphatic polycarbonate and inorganic particles and another structure contacted therewith are not easily peeled at the interface between the two by an external force, a laminated ceramic electronic component precursor including the above composite structure, a method for manufacturing the above laminated ceramic electronic component precursor, and a method for manufacturing a laminated ceramic electronic component including the method for manufacturing the above laminated ceramic electronic component precursor.

[0014] Means for solving the problems

[0015] The present inventors have found that, in a composite structure containing a structure including an aliphatic polycarbonate and inorganic particles, a first structure including an aliphatic polycarbonate and a first inorganic particle is compounded with a second structure including a branched polymer and a second inorganic particle, and as the branched polymer, a polymer whose molecular chain has a main chain formed of a cellulose-based polymer and a side chain formed of an aliphatic polycarbonate or an aliphatic polyester is used, thereby the above problems can be solved, and thus the present application has been achieved. More specifically, the present application provides the following (1) to (6).

[0016] (1) A composite structure including a first structure and a second structure,

[0017] The first structure is in contact with the second structure,

[0018] The first structure includes an aliphatic polycarbonate and a first inorganic particle,

[0019] The second structure includes a branched polymer and a second inorganic particle,

[0020] The molecular chain of the branched polymer has a main chain formed of a cellulose-based polymer and a side chain formed of an aliphatic polycarbonate or an aliphatic polyester,

[0021] The side chain can be linear or branched,

[0022] The side chain can be bonded to two or more main chains to crosslink the two or more main chains.

[0023] (2) The composite structure according to (1), wherein,

[0024] The first sheet-like structure and the second sheet-like structure are repeatedly and alternately stacked.

[0025] The first structure contains metal particles and ceramic particles as the first inorganic particles.

[0026] The second structure contains ceramic particles as the second inorganic particles, and may also contain metal particles.

[0027] In the first structure, the volume of the metal particles is larger than that of the ceramic particles.

[0028] In the second structure, the volume of ceramic particles is larger than that of metal particles.

[0029] (3) According to the composite structure described in (1), wherein,

[0030] The first sheet-like structure and the second sheet-like structure are repeatedly and alternately stacked.

[0031] The first structure contains ceramic particles as the first inorganic particles, and may also contain metal particles.

[0032] The second structure contains metal particles and ceramic particles as the second inorganic particles.

[0033] In the first structure, the volume of the ceramic particles is larger than that of the metal particles.

[0034] In the second structure, the volume of the metal particles is larger than that of the ceramic particles.

[0035] (4) A laminated ceramic electronic component precursor comprising the composite structure described in (2) or (3).

[0036] (5) A method for manufacturing a laminated ceramic electronic component precursor, comprising cutting the composite structure described in (2) or (3) along a direction perpendicular or substantially perpendicular to the surface direction of the composite structure.

[0037] (6) A method for manufacturing a laminated ceramic electronic component, comprising:

[0038] The method described in (5) is used to manufacture the precursor of the multilayer ceramic electronic component, and

[0039] The precursor of the laminated ceramic electronic component is fired.

[0040] Invention Effects

[0041] According to the present invention, it is possible to provide a composite structure containing a structure comprising aliphatic polycarbonate and inorganic particles, wherein the structure comprising aliphatic polycarbonate and inorganic particles and other structures in contact with it are not easily separated by external force at the interface between them; a laminated ceramic electronic component precursor comprising the above-mentioned composite structure; a method for manufacturing the above-mentioned laminated ceramic electronic component precursor; and a method for manufacturing a laminated ceramic electronic component including the method for manufacturing the above-mentioned laminated ceramic electronic component precursor. Detailed Implementation

[0042] Composite Structures

[0043] The composite structure comprises a first structure and a second structure. Within the composite structure, the first structure and the second structure are connected.

[0044] The first structure comprises aliphatic polycarbonate and a first inorganic particle.

[0045] The second structure comprises a branched polymer and a second inorganic particle.

[0046] Branched polymers have a main chain formed from a cellulose-based polymer and side chains formed from aliphatic polycarbonate or aliphatic polyester. The side chains can be linear or branched. The side chains can bond to two or more of the main chains, thus crosslinking the main chains.

[0047] The first structure comprises an aliphatic polycarbonate, and the second structure comprises a branched polymer having a backbone formed from an aliphatic polycarbonate or an aliphatic polyester, thereby achieving a good fit between the first and second structures. This is because the aliphatic polycarbonate and the aforementioned branched polymer exhibit high affinity based on the similarity of their chemical structures.

[0048] Therefore, when an external force is applied to the composite structure, it is not easy for delamination to occur at the interface where the first structure and the second structure contact each other.

[0049] For the first and second structures that constitute the composite structure, there are no particular limitations on their shape, structure, or size, as long as they can be composited while in contact with each other.

[0050] Examples of shapes that can be used for the first and second structures include sheet-like, prism-like, and cylindrical shapes. Prism-like shapes include cuboid, cube, triangular prism, and pentagonal prism shapes.

[0051] The shapes of the first and second structures can also be three-dimensional shapes that can fit together in a way that allows their contact surfaces to closely meet.

[0052] When the composite structure is formed by a sheet-like first structure and a sheet-like second structure, the composite structure is preferably a laminate formed by stacking the first structure and the second structure.

[0053] As described above, the first structure and the second structure fit together well. Therefore, even if an external force is applied to the laminate, interlaminar delamination is not likely to occur.

[0054] Regarding preferred examples of composite structures as laminates, the following composite structures can be cited, wherein...

[0055] The first sheet-like structure and the second sheet-like structure are repeatedly and alternately stacked.

[0056] The first structure contains metal particles and ceramic particles as the first inorganic particles.

[0057] The second structure may contain ceramic particles as the second inorganic particles, or it may contain metal particles.

[0058] In the first structure, the volume of the metal particles is larger than that of the ceramic particles.

[0059] In the second structure, the volume of ceramic particles is larger than that of metal particles.

[0060] Another preferred example of a composite structure as a laminated body is the following composite structure, wherein...

[0061] The first sheet-like structure and the second sheet-like structure are repeatedly and alternately stacked.

[0062] The first structure may contain ceramic particles as the first inorganic particles, or it may contain metal particles.

[0063] The second structure contains metal particles and ceramic particles as the second inorganic particles.

[0064] In the first structure, the volume of the ceramic particles is larger than that of the metal particles.

[0065] In the second structure, the volume of the metal particles is larger than that of the ceramic particles.

[0066] In the above-mentioned composite structure as a layered body, the ceramic particles and metal particles contained in the first structure and the second structure as inorganic particles will be described later as components of the first structure and the second structure.

[0067] The aforementioned composite structure is preferably used in the manufacture of multilayer ceramic electronic components. Examples of multilayer ceramic electronic components include multilayer ceramic capacitors, inductors, piezoelectric elements, and thermistors. In multilayer ceramic electronic components such as multilayer ceramic capacitors, dielectric layers and internal electrode layers are typically stacked alternately.

[0068] For example, when the multilayer ceramic electronic component is a multilayer ceramic capacitor, the thickness of the multilayer dielectric layer is preferably 1.0 μm or less, more preferably 0.4 μm or less. The thickness of the multilayer dielectric layer is preferably 0.15 μm or more. The thickness of the multilayer dielectric layer is preferably 0.15 μm or more and 1.0 μm or less, more preferably 0.15 μm or more and 0.4 μm or less.

[0069] In a composite structure that is preferably used for manufacturing laminated ceramic electronic components, the total number of dielectric layers is preferably 15 or more and 700 or less.

[0070] In the above-mentioned composite structure, the second structure containing ceramic particles as the second inorganic particles and may also contain metal particles in a sheet-like form, or the first structure containing ceramic particles as the first inorganic particles and may also contain metal particles in a sheet-like form, is rich in ceramic particles as a dielectric, and a dielectric layer is provided by firing.

[0071] As described below, the second and first structures of the dielectric layer may also contain additives.

[0072] Regarding the content of ceramic particles in the second structure of the dielectric layer, it is preferably 45% by volume or more and 70% by volume or less, more preferably 55% by volume or more and 65% by volume or less, relative to the total volume of the branched polymer contained in the second structure, the volume of the second inorganic particles, and the volume of the additives.

[0073] Regarding the content of ceramic particles in the first structure of the dielectric layer, it is preferably 45% by volume or more and 70% by volume or less, more preferably 55% by volume or more and 65% by volume or less, relative to the total volume of the aliphatic polycarbonate contained in the first structure, the volume of the first inorganic particles, and the volume of the additives.

[0074] Regarding volume, one can observe the cross-section of the central part of the structure and convert it according to the area of ​​each particle.

[0075] The sheet-like second structure or sheet-like first structure that provides the dielectric layer is called a green sheet. Typically, the sheet-like second structure or sheet-like first structure is formed using a paste for forming the second structure (described later) or a paste for forming the first structure (described later) by known methods such as die-coating or blade coating. The formed film made of the paste is preferably dried. The thickness of the sheet-like second structure or sheet-like first structure after forming and drying is preferably 4 μm or less, more preferably 3 μm or less.

[0076] When the multilayer ceramic electronic component is a multilayer ceramic capacitor, the thickness of the multilayer internal electrode layer is preferably 0.20 μm or more and 1.0 μm or less, more preferably 0.20 μm or more and 0.80 μm or less.

[0077] In a composite structure that is preferably used for manufacturing laminated ceramic electronic components, the total number of internal electrode layers is preferably 15 or more and 700 or less.

[0078] In the above-mentioned composite structure, the first sheet-like structure containing metal particles and ceramic particles as the first inorganic particles, or the second sheet-like structure containing metal particles and ceramic particles as the second inorganic particles, is rich in metal particles, and an internal electrode layer is provided by firing.

[0079] From the perspective of the dispersibility and dispersion stability of metal particles, the preferred structure of the internal electrode layer is a second structure containing the branched polymer described later.

[0080] As described below, the first and second structures of the internal electrode layer may contain additives.

[0081] Regarding the content of metal particles in the first structure of the internal electrode layer, it is preferably 50% by volume or more and 75% by volume or less, more preferably 60% by volume or more and 70% by volume or less, relative to the total volume of the aliphatic polycarbonate contained in the first structure, the volume of the first inorganic particles, and the volume of the additives.

[0082] Regarding the content of metal particles in the second structure of the internal electrode layer, it is preferably 50% by volume or more and 75% by volume or less, more preferably 60% by volume or more and 70% by volume or less, relative to the total volume of the branched polymer contained in the second structure, the volume of the second inorganic particles, and the volume of the additives.

[0083] Regarding volume, one can observe the cross-section of the central part of the structure and convert it according to the area of ​​each particle.

[0084] Regarding the content of ceramic particles in the first structure of the internal electrode layer, it is preferably 3% by volume or more and 15% by volume or less, more preferably 5% by volume or more and 10.5% by volume or less, relative to the total volume of the aliphatic polycarbonate contained in the first structure, the volume of the first inorganic particles, and the volume of the additives.

[0085] Regarding the content of ceramic particles in the second structure of the internal electrode layer, it is preferably 3% by volume or more and 15% by volume or less, more preferably 5% by volume or more and 10.5% by volume or less, relative to the total volume of the branched polymer contained in the second structure, the volume of the second inorganic particles, and the volume of the additives.

[0086] Regarding the sheet-like first structure or sheet-like second structure providing the internal electrode layer, typically, a paste for forming the second structure (described later) or a paste for forming the first structure (described later) is used on the second structure or the first structure, which serves as a green sheet providing the dielectric layer, and the sheet is formed by printing methods such as gravure printing or screen printing. The thickness of the sheet-like first structure or sheet-like second structure providing the internal electrode layer after printing and drying is preferably, for example, 1.5 μm or less.

[0087] The shape of the internal electrode layer is not particularly limited. Regarding the shape of the internal electrode layer, a rectangle is preferred when viewed from a direction perpendicular to the surface of the internal electrode layer, but a coil shape or the like is also acceptable. The shape of the sheet-like first structure or sheet-like second structure of the internal electrode layer corresponds to the shape of the internal electrode layer to be formed.

[0088] By stacking and pressing together multiple two-layer structures, each having an internal electrode layer as either the second or first structure on a green sheet that serves as the first or second structure, a laminate that can be preferably used as a precursor for a laminated ceramic electronic component can be obtained. Pressing can be performed using methods such as isostatic pressing.

[0089] Laminated ceramic electronic components can be manufactured by: firing the composite structure itself, which is a laminate, and then attaching a configuration corresponding to the type of laminated ceramic electronic component to the fired laminate; or, attaching a configuration corresponding to the type of laminated ceramic electronic component to the composite structure, which is a laminate, to obtain a laminate, and then firing the obtained laminate.

[0090] In other words, the composite structure described above, which is a laminate, can be preferably used in the manufacture of the laminated ceramic electronic component.

[0091] Laminated ceramic electronic components are preferably manufactured by the following method. First, a laminate is formed by stacking a sheet-like structure providing a dielectric layer and a sheet-like structure providing an internal electrode layer. Next, the resulting laminate is cut along a direction perpendicular or substantially perpendicular to the plane direction of the laminate by a method such as die-cutting to form a laminate block of desired size. Then, the resulting laminate block is subjected to known processing, including firing, thereby manufacturing a laminated ceramic electronic component. Such a laminate block, or a laminate block obtained by performing known processing, is equivalent to a precursor of a laminated ceramic electronic component.

[0092] When a composite structure that is a laminate is cut, interlaminar delamination is likely to occur due to shear forces applied to the cut surface. However, when a laminate structure containing a first structure of aliphatic polycarbonate and a second structure containing a branched polymer with a specific structure is cut by methods such as compression cutting, interlaminar delamination near the cut surface is less likely to occur.

[0093] The first and second structures will be explained below.

[0094] <Structure 1>

[0095] As described above, the first structure comprises aliphatic polycarbonate and first inorganic particles. The first structure may also contain other components besides aliphatic polycarbonate and first inorganic particles, provided that the desired effect is not impaired.

[0096] The following describes the components that the first structure may contain and the method of forming the first structure.

[0097] [Aliphatic polycarbonate]

[0098] As an aliphatic polycarbonate, there are no particular limitations as long as it can form the first structure. Previously known aliphatic polycarbonates can be used as the component of the first structure.

[0099] Examples of aliphatic polycarbonates include those comprising the following formula (1):

[0100] -(-O-CO-O-CR 1 R 2 -CR 3 R 4 -)-···(1)

[0101] The resin of the structural unit shown.

[0102] In equation (1), R 1 R 2 R 3 and R 4Each is independently a hydrogen atom, or an alkyl group having 1 or more but less than 10 carbon atoms that may have substituents. R 1 R 2 R 3 and R 4 (At least two of the atoms can bond together to form a ring, constituting an aliphatic ring with 3 or more atoms but less than 10.)

[0103] As R 1 R 2 R 3 and R 4 The alkyl group, which can have substituents, can have a straight-chain or branched-chain structure. As R... 1 R 2 R 3 and R 4 The alkyl group having substituents preferably has 1 or more and 4 or less carbon atoms, more preferably 1 or 2. It should be noted that the number of carbon atoms of the substituents is not included in the number of carbon atoms of the alkyl group.

[0104] Regarding R 1 R 2 R 3 and R 4 Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

[0105] As R 1 R 2 R 3 and R 4 When the alkyl group has substituents, the number of substituents bonded to the alkyl group is not particularly limited within a range that does not impair the desired effect. The number of substituents bonded to the alkyl group is preferably 1 or 2.

[0106] Regarding R 1 R 2 R 3 and R 4 Specific examples of substituents that an alkyl group may have include hydroxyl, alkoxy, ester, silyl, mercapto, cyano, nitro, sulfonyl, formyl, carboxyl, and halogen atoms.

[0107] The number of carbon atoms in the alkoxy group as a substituent is not particularly limited, but is preferably 1 or more and 4 or less, more preferably 1 or 2. Specific examples of preferred alkoxy groups as substituents include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, sec-butyloxy, and tert-butyloxy.

[0108] Specific examples of preferred halogen atoms as substituents include fluorine, chlorine, bromine, and iodine atoms.

[0109] R 1 R 2 R 3 and R 4 It can contain one or more groups. For example, R 1 R 2 R 3 and R 4 They can be the same group. They can be: R 1 R 2 and R 3 They are the same group, R 4 Is with R 1 R 2 and R 3 Different groups. It can be: R 1 R 3 and R 4 They are the same group, R 2 Is with R 1 R 3 and R 4 Different groups. R 1 R 2 R 3 and R 4 It can be four different groups.

[0110] R 1 R 2 R 3 and R 4 At least two of the components can bond to form an aliphatic ring with 3 or more but less than 10 atoms. The aliphatic ring can be a saturated aliphatic ring or an unsaturated aliphatic ring. The aliphatic ring can have substituents. The number of substituents that the aliphatic ring can have is not particularly limited, provided that the desired effect is not impaired. When the aliphatic ring has substituents, the number of substituents is preferably 1 or 2.

[0111] Specific examples of aliphatic rings include cyclopentane rings, cyclopentene rings, cyclohexane rings, cyclohexene rings, and cycloheptane rings.

[0112] Aliphatic rings can have substituents such as alkyl, alkoxy, acyloxy, alkoxycarbonyl, silyl, mercapto, cyano, nitro, sulfonyl, formyl, and halogen atoms.

[0113] Specific examples of alkyl groups that are substituents include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0114] Specific examples of alkoxy groups as substituents include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, sec-butyloxy, and tert-butyloxy.

[0115] Specific examples of acyloxy groups as substituents include acetoxy, propionyloxy, butyryloxy, isobutyryloxy, and pivaloyloxy.

[0116] Specific examples of alkoxycarbonyl groups as substituents include methoxycarbonyl, ethoxycarbonyl, and tert-butoxycarbonyl.

[0117] Specific examples of halogen atoms that can be used as substituents include fluorine, chlorine, bromine, and iodine atoms.

[0118] In addition to aliphatic polycarbonates containing the structural units shown in formula (1) above, polytrimethylene carbonate, polytetramethylene carbonate, polyhexamethylene carbonate, poly-2,2-dimethyltrimethylene carbonate and poly-1,4-cyclohexanedimethyl carbonate are also preferably used as aliphatic polycarbonates.

[0119] Among the aliphatic polycarbonates described above, polyethylene carbonate, polypropylene carbonate, polytriethylene carbonate, and polytetramethylene carbonate are preferred, polypropylene carbonate and polytetramethylene carbonate are more preferred, and polypropylene carbonate is even more preferred.

[0120] The aforementioned composite structure is subject to sintering. When using the preferred aliphatic polycarbonate, there is less residue after thermal decomposition during sintering, making it easier to form the first structure with the desired shape. Furthermore, these aliphatic polycarbonates exhibit excellent affinity for the first inorganic particles.

[0121] Aliphatic polycarbonates can be used alone or in combination of two or more types.

[0122] The end groups of aliphatic polycarbonates can be modified without compromising the desired effect. Examples of end group modification include modifications using acid anhydrides, cyclic anhydrides, acyl halides, and isocyanate compounds.

[0123] Without compromising the desired effect, aliphatic polycarbonate may partially comprise structural units other than polycarbonate structural units, such as polyether structural units, polyester structural units, polyamide structural units, and polyacrylate structural units. The content of other structural units in the aliphatic polycarbonate is preferably 10 mol% or less, more preferably 5 mol% or less, further preferably 3 mol% or less, and particularly preferably 1 mol% or less, relative to the total molar number of all structural units in the aliphatic polycarbonate.

[0124] [The first inorganic particle]

[0125] The first structure contains a first inorganic particle. As the first inorganic particle, any inorganic particle that has been conventionally added to various resin compositions can be used without particular limitation.

[0126] As the first inorganic particle, ceramic particles and / or metal particles are typically preferred.

[0127] As described above, a preferred example of a composite structure is a laminate, which is useful as a precursor to a multilayer ceramic electronic component. In the case where the first structure is a green sheet providing a dielectric layer in a multilayer ceramic electronic component, or where the first structure is a conductive sheet formed from a conductive paste providing an internal electrode layer in a multilayer ceramic electronic component, ceramic particles are useful as a constituent component of the first structure.

[0128] For ceramic particles, it is preferred that the constituent materials include at least one selected from Ba, Ti, Sr, Ca and Zr.

[0129] Preferred examples of ceramic particles include barium titanate particles, calcium titanate particles, strontium titanate particles, and lead zirconate titanate particles.

[0130] As ceramic particles, one type can be used alone, or two or more types can be used in combination.

[0131] In the case where the first structure is a conductive sheet formed by a conductive paste that provides an internal electrode layer in a stacked ceramic electronic component, metal particles, which are first inorganic particles, are useful as constituent components of the first structure.

[0132] The metal constituting the metal particles is preferably selected from at least one of Ni, Cu, Ag, Pt and Au.

[0133] Metal particles can contain two or more types of metal particles. Metal particles can also be alloy particles containing two or more metals.

[0134] The content of the first inorganic particles in the first structure is not particularly limited. The content of the first inorganic particles in the first structure is appropriately determined considering the application of the composite structure and the composition of the second structure. Typically, the content of the first inorganic particles is preferably 5% by volume or more and 95% by volume or less relative to the volume of the first structure, more preferably 10% by volume or more and 90% by volume or less.

[0135] [Plasticizer]

[0136] To improve the processability of the composite structure, the first structure may also contain plasticizers other than aliphatic polycarbonate and the first inorganic particles.

[0137] Preferred examples of plasticizers include phthalic acid-based plasticizers such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dibutyl benzyl phthalate, and alkyl butyl benzyl phthalate; diol-based plasticizers such as diethylene glycol dibenzoate, dipropylene glycol dibenzoate, and polyethylene glycol; phosphoric acid-based plasticizers such as tricresyl phosphate, tributoxyethyl phosphate, 2-ethylhexyl diphenyl phosphate, and isodecyl diphenyl phosphate; citric acid-based plasticizers such as triethyl O-acetyl citrate and tributyl O-acetyl citrate; adipic acid-based plasticizers such as dibutyl adipate and dihexyl adipate; carbonate-based plasticizers such as ethylene carbonate and propylene carbonate; and epoxy-based plasticizers such as epoxidized soybean oil and epoxidized linseed oil.

[0138] [Other additives]

[0139] Depending on the intended use of the composite structure, the first structure may also contain other additives besides aliphatic polycarbonate, the first inorganic particles, and plasticizers.

[0140] Other additives include, for example, at least one selected from dispersants and antistatic agents.

[0141] There are no particular restrictions on the amount of other additives used, as long as they do not impair the desired effect. The amount of other additives used should be determined appropriately, taking into account the generally usable amount corresponding to the type of additive.

[0142] [Method for forming the first structure]

[0143] There are no particular limitations on the method of forming the first structure. When the proportion of aliphatic polycarbonate in the first structure is sufficiently high, melt molding methods such as injection molding and extrusion molding can be used as methods of forming the first structure.

[0144] Furthermore, aliphatic polycarbonate is soluble in a variety of solvents. Therefore, the first structure can be obtained by preparing a paste for forming the first structure by adding aliphatic polycarbonate, an organic solvent, first inorganic particles, and other additives as needed. The resulting paste is then shaped into the desired shape by methods such as sheet coating, doctor blade coating, or injection molding. Next, the shaped paste is dried.

[0145] Depending on the particle size of the first inorganic particle and the viscosity of the paste used to form the first structure, gravure printing or screen printing can also be used as methods to form the paste into sheets.

[0146] In addition, the first structure can be formed by uniformly mixing aliphatic polycarbonate, the first inorganic particles and other additives as needed in a solid state, filling the resulting mixture into a mold, and then compressing it while heating it as needed.

[0147] When using a paste to form the first structure, preferred examples of organic solvents added to the paste include alkane alcohols such as isopropanol; hydrocarbon solvents such as toluene, xylene, and isophorone; terpineol solvents such as terpineol and dihydroterpineol; ester solvents such as ethyl acetate, n-propyl acetate, n-butyl acetate, terpineol acetate, and dihydroterpineol acetate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl carbitol, etc. Diol ether solvents such as ethyl carbitol, butyl carbitol, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether; diol ester solvents such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate; carbonate solvents such as dimethyl carbonate and propylene carbonate; ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; and nitrogen-containing polar organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

[0148] There is no particular limitation on the amount of organic solvent used when preparing pastes. The amount of organic solvent used should be adjusted appropriately so that the viscosity of the paste is suitable for the printing or coating methods to be performed using the paste.

[0149] <Second Structure>

[0150] The second structure comprises a branched polymer and a second inorganic particle. Without compromising the desired effect, the second structure may also comprise other components besides the branched polymer and the second inorganic particle.

[0151] The following describes the components that the second structure may contain.

[0152] [Branched polymers]

[0153] Branched polymers have a main chain and branches. The main chain is formed from cellulose-based polymers. The branches are formed from aliphatic polycarbonates or aliphatic polyesters.

[0154] Branches can be straight or branched. Branches can bond with two or more main chains, thus crosslinking the main chains.

[0155] The second structure comprising the aforementioned branched polymer is well bonded to the first structure comprising aliphatic polycarbonate. Furthermore, the branched polymer effectively disperses the second inorganic particles.

[0156] In branched polymers, the ratio of the mass of the branched chain to the mass of the main chain, i.e., the grafting rate, is not particularly limited within a range that does not impair the desired effect. From the perspective that the branched polymer has a particularly good affinity with the aliphatic polycarbonate contained in the first structure, the grafting rate is preferably 10% by mass or more and 400% by mass or less, more preferably 50% by mass or more and 250% by mass or less.

[0157] The grafting rate can be determined by nuclear magnetic resonance spectroscopy (NMR analysis).

[0158] The mass-average molecular weight of the branched polymer is not particularly limited. Preferably, the mass-average molecular weight of the branched polymer is 50,000 or more and 1,000,000 or less, more preferably 100,000 or more and 600,000 or less. When the mass-average molecular weight of the branched polymer is within this range, the branched polymer exhibits good mechanical properties such as strength, elongation, and toughness, as well as good formability.

[0159] The following describes the manufacturing methods for main-chain, branched, and branched polymers.

[0160] (Main chain)

[0161] Branched polymers have a backbone formed from cellulose-based polymers. There are no particular limitations on the type of cellulose-based polymer, as long as the backbone has functional groups capable of bonding branches.

[0162] Preferred examples of cellulose-based polymers include cellulose; alkyl celluloses such as methylcellulose, ethylcellulose, n-propylcellulose, isopropylcellulose, n-butylcellulose, tert-butylcellulose, and n-hexylcellulose; hydroxyalkyl celluloses such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxybutylcellulose; cellulose esters such as cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose acetate propionate, and cellulose acetate butyrate; carboxyalkyl celluloses such as carboxymethylcellulose, carboxyethylcellulose, and carboxypropylcellulose; and cellulose derivatives such as nitrocellulose, aldehyde cellulose, dialdehyde cellulose, and sulfonated cellulose.

[0163] Branched polymers can contain two or more branched polymer molecules with different types of cellulose-based polymers as the main chain.

[0164] In terms of ease of manufacturing branched polymers and ease of obtaining branched polymers with excellent compatibility with the aliphatic polycarbonate contained in the first structure, the cellulose polymer is preferably selected from at least one of alkyl cellulose, hydroxyalkyl cellulose and cellulose ester.

[0165] Among the preferred cellulose polymers described above, at least one is selected from methylcellulose, ethylcellulose, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate.

[0166] The mass-average molecular weight of the cellulose polymer is not particularly limited. The mass-average molecular weight of the cellulose polymer is preferably 5,000 or more, more preferably 10,000 or more, and particularly preferably 100,000 or more. The mass-average molecular weight of the cellulose polymer is preferably 1,000,000 or less, more preferably 750,000 or less, and even more preferably 500,000 or less.

[0167] More specifically, the molecular weight of the cellulose polymer is preferably 5,000 or more and 1,000,000 or less, more preferably 10,000 or more and 750,000 or less, and even more preferably 10,000 or more and 750,000 or less.

[0168] The degree of substitution of cellulose polymers is not particularly limited within a range that does not impair the desired effect. The degree of substitution of cellulose polymers is preferably 2 or more and 3 or less, typically 2.5.

[0169] The degree of substitution of cellulose polymers is the total number of hydroxyl groups in the structural units of cellulose polymers that are replaced by groups other than those in the branched chain.

[0170] (Side chain)

[0171] Branched polymers have branches bonded to the main chain formed by cellulose-based polymers. These branches are formed from aliphatic polycarbonates or aliphatic polyesters. The branches can be linear or branched.

[0172] Typically, a branch bonds to only one main chain. A branch can also bond to two or more main chains, thus crosslinking the two or more main chains.

[0173] As long as the branch can be formed in a state of being combined with the main chain, or can be combined with the main chain, there are no particular limitations on the aliphatic polycarbonate or aliphatic polyester that constitute the branch.

[0174] Typical examples of branched aliphatic polycarbonates or aliphatic polyesters are shown in the following description of a method for manufacturing branched polymers.

[0175] (Manufacturing method of branched polymers)

[0176] There are no particular restrictions on the manufacturing methods of branched polymers. Typically, graft polymerization is used. The graft polymerization method can be appropriately selected from a variety of known methods depending on the type of branching.

[0177] As a graft polymerization method, ring-opening polymerization can be used, for example. By ring-opening polymerization of cyclic carbonate compounds, lactones, or other cyclic ester compounds in the presence of a cellulose-based polymer, aliphatic polycarbonates or aliphatic polyesters are generated as graft chains on the molecular chain of the cellulose-based polymer.

[0178] For example, propylene carbonate, as a cyclic compound, has branches formed from polypropylene carbonate. Butylene carbonate, as a cyclic compound, has branches formed from polybutylene carbonate. Cyclohexene carbonate, as a cyclic compound, has branches formed from polycyclohexene carbonate. Trimethylene carbonate, as a cyclic compound, has branches formed from polymethylene carbonate. 2,2-Dimethyltrimethylene carbonate, as a cyclic compound, has branches formed from poly(2,2-dimethyltrimethylene carbonate).

[0179] ε-Caprolactone, as a cyclic compound, is branched from polycaprolactone, an aliphatic polyester. L-Lylactone, as a cyclic compound, is branched from polylactic acid, the L-form of an aliphatic polyester. D-Lylactone, as a cyclic compound, is branched from polylactic acid, the D-form of an aliphatic polyester. meso-lactone, as a cyclic compound, is branched from polylactic acid, the syndiotactic form of an aliphatic polyester. β-Proprolactone, as a cyclic compound, is branched from poly(3-hydroxypropionic acid), the D-form of an aliphatic polyester. β-Butyrolactone, as a cyclic compound, is branched from poly(3-hydroxybutyric acid), an aliphatic polyester. γ-Butyrolactone, as a cyclic compound, is branched from poly(4-hydroxybutyric acid), an aliphatic polyester. δ-Valactone, as a cyclic compound, is branched from poly(3-hydroxyvalerate), an aliphatic polyester. p-Dioxanone, as a cyclic compound, is given as poly(p-dioxanone) as a branched aliphatic polyester.

[0180] Typically, ring-opening polymerization is carried out in the presence of a catalyst. Specific examples of catalysts that can be used for ring-opening polymerization include alkali metals such as sodium and potassium; metal-containing catalysts such as sodium hydroxide, potassium hydroxide, triethylaluminum, triisopropoxyaluminum, n-butyllithium, tetraisopropoxytitanium, titanium tetrachloride, tetraisopropoxyzirconium, tin tetrachloride, sodium stannate, tin octoate, dibutyltin dilaurate, and diethylzinc; basic organic compounds such as pyridine, 4-N,N-dimethylaminopyridine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBT); acid catalysts such as hydrochloric acid, acetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, diphenylphosphoric acid, and phenol; and N-heterocyclic carbenes such as 1,3-bis(2-propyl)-4,5-dimethylimidazol-2-ylene and 1,3-diisopropylimidazol-2-ylene.

[0181] A single catalyst can be used alone, or two or more catalysts can be used in combination.

[0182] When using cyclic carbonates for ring-opening polymerization, it is also preferable to use a co-catalyst together with the catalyst. Specific examples of co-catalysts include N-cyclohexyl-N'-phenylthiourea, N,N'-bis[3,5-bis(trifluoromethyl)phenyl]thiourea, N-[3,5-bis(trifluoromethyl)phenyl]-N'-cyclohexylthiourea, and (-)-stigmine.

[0183] The amount of catalyst used for ring-opening polymerization is appropriately determined considering the amount of catalyst used in previously known ring-opening polymerization reactions. Typically, the amount of catalyst used is preferably 0.001 moles or more, more preferably 0.005 moles or more, relative to 1 mole of the cyclic compound. The amount of catalyst used is preferably 0.2 moles or less, more preferably 0.1 moles or less, relative to 1 mole of the cyclic compound.

[0184] More specifically, the amount of catalyst used is preferably 0.001 moles or more and 0.2 moles or less, more preferably 0.005 moles or more and 0.1 moles or less, relative to 1 mole of the cyclic compound.

[0185] The amount of co-catalyst used is the same as the amount of catalyst used.

[0186] Ring-opening polymerization is preferably carried out in the presence of a solvent. The type of solvent is not particularly limited as long as it does not hinder the ring-opening polymerization reaction.

[0187] Preferred examples of solvents include aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; halogenated hydrocarbon solvents such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, chlorobenzene, and bromobenzene; ether solvents such as ethylene glycol dimethyl ether (monoethylene glycol dimethyl ether), diethylene glycol dimethyl ether (diethylene glycol dimethyl ether), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and anisole; ester solvents such as ethyl acetate, n-propyl acetate, and isopropyl acetate; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

[0188] There is no particular limitation on the amount of solvent used, as long as the ring-opening polymerization reaction proceeds well. For example, the amount of solvent used is preferably 100 parts by mass or more and 1000 parts by mass or less relative to 100 parts by mass of the cyclic compound.

[0189] Typically, ring-opening polymerization is carried out by adding cellulose resin, cyclic compound, catalyst, and co-catalyst and / or solvent as needed into a reaction vessel, stirring the mixture in the reaction vessel.

[0190] The preferred reaction temperature for ring-opening polymerization varies depending on the cyclic compound, the type of catalyst, and the amount of catalyst used. Typically, the reaction temperature for ring-opening polymerization is preferably -80°C or higher, more preferably -40°C or higher, and even more preferably 0°C or higher. In terms of balancing good yield and suppression of side reactions, the reaction temperature for ring-opening polymerization is preferably 250°C or lower, more preferably 200°C or lower, and even more preferably 150°C or lower.

[0191] More specifically, the reaction temperature is preferably -80°C or higher and 250°C or lower, more preferably -40°C or higher and 200°C or lower, and even more preferably 0°C or higher and 150°C or lower.

[0192] The reaction time for ring-opening polymerization varies depending on the type of cyclic compound, the type of catalyst, and the amount of catalyst used. Typically, the reaction time for ring-opening polymerization is preferably more than 1 hour and less than 40 hours.

[0193] The amount of cyclic compound used in ring-opening polymerization should be appropriately determined based on the grafting rate mentioned above.

[0194] Another preferred example of a method for manufacturing branched polymers is the copolymerization of cyclic ethers with carbon dioxide in the presence of a cellulose resin. According to this copolymerization reaction, branches formed from aliphatic polycarbonate are generated. The cellulose resin is as described above.

[0195] As a cyclic ether, the appropriate cyclic ether is selected that corresponds to the aliphatic polycarbonate that serves as the branch.

[0196] Preferred examples of cyclic ethers include ethylene oxide, propylene oxide, trimethylene oxide (oxetane), 3,3-dimethyltrimethylmethylene oxide (3,3-dimethyloxetane), 1,2-epoxybutane, 2,3-epoxybutane, isobutane oxide, 1-pentene oxide, 2-pentene oxide, 1-hexene oxide, 1-octene oxide, 1-decene oxide, cyclopentene oxide, cyclohexene oxide, vinylcyclohexane oxide, 3-phenylepoxypropane, 3,3,3-trifluoroepoxypropane, 2-phenoxypropane, 3-naphthoxypropane, butadiene monooxide, 3-vinyloxypropane, and 3-trimethylsilyloxypropane.

[0197] Among the aforementioned cyclic ethers, ethylene oxide, propylene oxide, trimethylene oxide, and 1,2-epoxybutane are preferred from the perspectives of excellent polymerization reactivity and affinity between the branched polymer and the aliphatic polycarbonate contained in the first structure. Ethylene oxide, propylene oxide, and trimethylene oxide are more preferred.

[0198] The following illustrates an example of an aliphatic polycarbonate produced by copolymerization of a cyclic ether and carbon dioxide. Ethylene oxide gives polyethylene carbonate. Propylene oxide gives polypropylene carbonate. Trimethylene oxide gives polytrimethylene carbonate.

[0199] The copolymerization of cyclic ethers with carbon dioxide is carried out in the presence of a metal catalyst. Preferred examples of metal catalysts include zinc-based, aluminum-based, chromium-based, and cobalt-based catalysts. Among these, zinc-based and cobalt-based catalysts are preferred based on their polymerization activity.

[0200] Preferred examples of zinc-based catalysts include diethylzinc-aqueous catalysts, diethylzinc-pyrogallol catalysts, bis((2,6-diphenyl)phenoxy)zinc, N-(2,6-diisopropylphenyl)-3,5-di-tert-butylsalicylaldehyde imine zinc, 2-((2,6-diisopropylphenyl)amide)-4-((2,6-diisopropylphenyl)imino)-2-pentenoic acid acetate, zinc adipate, and zinc glutarate.

[0201] Preferred specific examples of cobalt-based catalysts include cobalt acetate-acetic acid catalysts, N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-cyclohexanediaminoacetate cobalt, N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-cyclohexanediaminopentafluorobenzoate cobalt, N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-cyclohexanediaminocobalt chloride, and N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-cyclohexanediaminocobalt chloride. Cobalt nitrate of 1,2-cyclohexanediamino, cobalt oxide of 3,5-di-tert-butylsalicyl)-1,2-cyclohexanediamino-2,4-dinitrophenyl, cobalt chloride of tetraphenylporphyrin, cobalt acetate of tetraphenylporphyrin, cobalt chloride of N,N'-bis[2-(ethoxycarbonyl)-3-oxobutylidene]-1,2-cyclohexanediamine, and cobalt pentafluorobenzoate of N,N'-bis[2-(ethoxycarbonyl)-3-oxobutylidene]-1,2-cyclohexanediamine.

[0202] Cobalt-based catalysts are preferably used in conjunction with a co-catalyst. Specific examples of co-catalysts include pyridine, 4-N,N-dimethylaminopyridine, N-methylimidazolium, tetrabutylammonium chloride, tetrabutylammonium acetate, triphenylphosphine, bis(triphenylphosphine)ammonium chloride, and bis(triphenylphosphine)ammonium acetate.

[0203] Regarding the amount of catalyst used in the copolymerization of cyclic ethers and carbon dioxide, it is appropriately determined taking into account the amounts of catalysts known previously for this copolymerization reaction. Typically, the amount of catalyst used is preferably 0.001 moles or more, more preferably 0.005 moles or more, relative to 1 mole of cyclic ether. The amount of catalyst used is preferably 0.2 moles or less, more preferably 0.1 moles or less, relative to 1 mole of cyclic ether.

[0204] More specifically, the amount of catalyst used is preferably 0.001 moles or more and 0.2 moles or less, more preferably 0.005 moles or more and 0.1 moles or less, relative to 1 mole of cyclic ether.

[0205] The amount of co-catalyst used is the same as the amount of catalyst used.

[0206] The copolymerization of cyclic ethers with carbon dioxide is preferably carried out in the presence of a solvent. The type of solvent is not particularly limited, as long as it does not hinder the copolymerization reaction.

[0207] Preferred examples of solvents include aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; halogenated hydrocarbon solvents such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, chlorobenzene, and bromobenzene; ether solvents such as ethylene glycol dimethyl ether (monoethylene glycol dimethyl ether), diethylene glycol dimethyl ether (diethylene glycol dimethyl ether), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and anisole; ester solvents such as ethyl acetate, n-propyl acetate, and isopropyl acetate; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

[0208] There are no particular limitations on the amount of solvent used, as long as the copolymerization reaction proceeds well. For example, the amount of solvent used is preferably 100 parts by mass or more and 1000 parts by mass or less relative to 100 parts by mass of the cyclic ether.

[0209] Typically, copolymerization is carried out by adding cellulose resin, cyclic ether, catalyst, and co-catalyst and / or solvent as needed into a reaction vessel, pressurizing carbon dioxide into the reaction vessel, and stirring the mixture in the reaction vessel.

[0210] The amount of cyclic ether and carbon dioxide used during copolymerization should be appropriately determined based on the grafting rate mentioned above.

[0211] Regarding the pressure of carbon dioxide inside the reaction vessel during copolymerization, from the perspective of ensuring a good reaction, using a gauge pressure at the reaction temperature, it is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, and even more preferably 0.5 MPa or more. From the perspective of avoiding the need for expensive pressure-resistant vessels with high pressure resistance and ensuring operational safety, the pressure of carbon dioxide inside the reaction vessel is preferably 20 MPa or less, more preferably 10 MPa or less, and may also be 5 MPa or less.

[0212] More specifically, the pressure of carbon dioxide in the reaction solution is preferably 0.1 MPa or more and 20 MPa or less, more preferably 0.2 MPa or more and 10 MPa or less, and even more preferably 0.5 MPa or more and 5 MPa or less, measured by a gauge manometer.

[0213] Copolymerization can also be carried out under supercritical carbon dioxide conditions.

[0214] The preferred reaction temperature for copolymerization varies depending on the type of cyclic ether, the type of catalyst, and the amount of catalyst used. Typically, the copolymerization reaction temperature is preferably 0°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher. In terms of balancing good yield and suppression of side reactions, the copolymerization reaction temperature is preferably 100°C or lower, more preferably 80°C or lower, and even more preferably 60°C or lower.

[0215] In the above respects, the reaction temperature for copolymerization is preferably 0°C or higher and 100°C or lower, more preferably 20°C or higher and 80°C or lower, and even more preferably 30°C or higher and 60°C or lower.

[0216] The reaction time for copolymerization varies depending on the type of cyclic ether, the type of catalyst, and the amount of catalyst used. Typically, the reaction time for ring-opening polymerization is preferably more than 1 hour and less than 40 hours.

[0217] The amount of cyclic compound used in ring-opening polymerization should be appropriately determined based on the grafting rate mentioned above.

[0218] In the case of aliphatic polyesters whose branches are formed by the condensation polymerization of aliphatic dicarboxylic acids such as polyethylene succinate, polyethylene adipate, polybutylene succinate, and polybutylene adipate with diols, branched polymers can also be manufactured by co-condensation polymerization of aliphatic dicarboxylic acids and diols corresponding to the structure of aliphatic polyesters in the presence of cellulose resins using conventional methods.

[0219] [Second Inorganic Particle]

[0220] As the second inorganic particle, the same inorganic particle as the first inorganic particle can be used without any particular restrictions. The second inorganic particle can be the same type of inorganic particle as the first inorganic particle, or it can be a different type of inorganic particle.

[0221] The type of the second inorganic particle is usually selected taking into account the purpose of the composite structure and the type of the first inorganic particle.

[0222] The second structure can contain two or more types of inorganic particles as the second inorganic particles.

[0223] [Other additives]

[0224] Depending on the application of the composite structure, the second structure may also contain other additives besides the branched polymer and the second inorganic particles.

[0225] Other additives include, for example, at least one selected from dispersants, plasticizers and antistatic agents.

[0226] There are no particular restrictions on the amount of other additives used, as long as they do not impair the desired effect. The amount of other additives used should be determined appropriately, taking into account the generally usable amount corresponding to the type of additive.

[0227] [Method for forming the second structure]

[0228] There are no particular limitations on the method for forming the second structure. The second structure can be formed using the same method as the first structure. When the proportion of branched polymer in the second structure is sufficiently high, melt molding methods such as injection molding and extrusion molding can be used as methods for forming the second structure.

[0229] Furthermore, the second structure is soluble in a variety of solvents. Therefore, the second structure can be obtained by preparing a paste for forming the second structure by adding a branched polymer, an organic solvent, a second inorganic particle, and other additives as needed, and then shaping the resulting paste into the desired shape by methods such as sheet coating, doctor blade coating, or injection molding, and then drying the shaped paste.

[0230] Depending on the particle size of the second inorganic particles and the viscosity of the paste used to form the second structure, gravure printing or screen printing can also be used as methods to form the paste into sheets.

[0231] In addition, the second structure can be formed by uniformly mixing the branched polymer, the second inorganic particles and other additives as needed in a solid state, filling the resulting mixture into a mold, and then heating and compressing it as needed.

[0232] When using a paste to form the second structure, the preferred example of the organic solvent added to the paste is the same as the preferred example of the organic solvent that can be used when preparing the paste for the first structure.

[0233] There is no particular limitation on the amount of organic solvent used when preparing pastes. The amount of organic solvent used should be adjusted appropriately so that the viscosity of the paste is suitable for the printing or coating methods to be performed using the paste.

[0234] There are no particular limitations on the method for combining the first structure and the second structure described above. For example, if the first structure and the second structure can be formed by injection molding, they can be combined by forming the first structure and the second structure simultaneously by a multi-color molding method such as a two-color molding method.

[0235] If the first structure and the second structure can be formed by extrusion molding, they can be combined by co-extrusion molding to form the first structure and the second structure simultaneously.

[0236] In addition, the first and second structures formed separately can be combined by methods such as hot pressing.

[0237] Example

[0238] The present invention will be further described in detail below through embodiments, but the present invention is not limited to these embodiments.

[0239] [Example 1]

[0240] (Preparation of dielectric paste)

[0241] 7.2 parts by mass of polypropylene carbonate, an aliphatic polycarbonate, were dissolved in 26 parts by mass of n-butyl acetate and 26 parts by mass of dimethyl carbonate. The polypropylene carbonate has carboxylic acid modified sites in its repeating structure. The proportion of carboxylic acid modified sites is 0.8 mol% of the total structure. To the resulting solution, 40 parts by mass of barium titanate particles (BET equivalent diameter 0.2 μm) as ceramic particles, 0.7 parts by mass of polyethylene glycol as a plasticizer, and 0.1 parts by mass of an antistatic agent were added. Next, the resulting suspension was dispersed in a ball mill for a specified time to obtain a dielectric paste.

[0242] (Preparation of raw slices)

[0243] Using the obtained dielectric paste, a sheet with a thickness of 1.4 μm after firing was formed by a doctor blade method. The formed sheet was then dried to obtain a green sheet. The obtained green sheet corresponds to the first structure.

[0244] (Preparation of conductive paste)

[0245] As a branched polymer, a resin having a main chain formed of ethyl cellulose and branches formed of polypropylene carbonate is used. This branched polymer is prepared by ring-opening polymerization of propylene carbonate in the presence of ethyl cellulose. The grafting rate of the branched polymer is 50% by mass.

[0246] (Coating of conductive paste)

[0247] The obtained conductive paste was applied to the green sheet using screen printing. The coated film was then dried and fired to form a coating film providing the internal electrode layer. The thickness of the coated film was 0.4 μm. The formed coated film corresponds to the second structure.

[0248] (Layered)

[0249] 218 green sheets with a coating film that provides an internal electrode layer through firing are stacked together, and green sheets without a coating film are stacked on the top and bottom layers. The whole is pressed together to obtain a stack containing a total of 220 green sheets.

[0250] (cut off)

[0251] The resulting laminate is divided by pressing and cutting with a cutting saw in a direction perpendicular to the surface direction of the laminate. The dimensions of the divided laminate are adjusted so that the dimensions of the surface perpendicular to the thickness direction are 1.0 mm × 0.5 mm when the divided laminate is fired.

[0252] (Firing)

[0253] For more than 100 segmented laminates, heat treatment was performed in an N2 gas stream at a maximum temperature of 270°C, followed by further heat treatment in an N2-H2O-H2 gas stream at a maximum temperature of 800°C. Then, in an N2-H2O-H2 gas stream, at an oxygen partial pressure of 1.8 × 10⁻⁶, heat treatment was carried out. -9 ~8.7×10 -10 The firing process was carried out under the conditions of MPa, heating rate of 100℃ / min, and maximum temperature of 1260℃. It should be noted that during firing, after reaching the maximum temperature of 1260℃, this temperature was maintained for 10 minutes, and then immediately cooled to near room temperature.

[0254] The thickness of the dielectric layer formed by firing the green sheet is 1.4 μm.

[0255] In the above processes, the delamination during the cutting process in the laminate and the occurrence of structural defects after firing were evaluated according to the following methods. The evaluation results are recorded in Table 1.

[0256] <Evaluation of interlayer delamination during pressure cutting>

[0257] For 100 laminates cut using a cutting saw, the cut surfaces were observed using an optical microscope to confirm whether there was interlayer delamination between the raw sheet and the coating film formed using conductive paste. The number of laminates with confirmed interlayer delamination is recorded in Table 1 as the interlayer delamination rate (%).

[0258] <Evaluation of the occurrence of structural defects after firing>

[0259] One hundred fired and segmented laminates were observed using an optical microscope to confirm the presence of structural defects such as cracks and delamination, which were believed to be caused by gases generated from resin decomposition. The number of laminates with confirmed structural defects is recorded in Table 1 as a structural defect incidence rate.

[0260] [Example 2]

[0261] As a branched polymer, a resin having a main chain formed of ethyl cellulose and a branch chain formed of polycaprolactone, an aliphatic polyester, is used. This branched polymer is prepared by ring-opening polymerization of caprolactone in the presence of ethyl cellulose. The grafting rate of the branched polymer is 100% by mass.

[0262] Except for using the branched polymer described above, the same procedures as in Example 1 were performed, and evaluations were conducted on interlayer delamination during die cutting and the occurrence of structural defects after firing. These evaluation results are recorded in Table 1.

[0263] [Comparative Example 1]

[0264] The resin used for preparing the dielectric paste was changed to polyvinyl butyral, and the resin used for preparing the conductive paste was changed to ethyl cellulose. Except as described above, the same procedures as in Example 1 were performed, and evaluations were conducted on interlayer delamination during die-cutting and the occurrence of structural defects after firing. These evaluation results are recorded in Table 1.

[0265] [Comparative Example 2]

[0266] The resin used for preparing the conductive paste was changed to ethyl cellulose. Except as described above, the same procedures as in Example 1 were performed, and evaluations were conducted on interlayer delamination during pressure cutting and the occurrence of structural defects after firing. These evaluation results are recorded in Table 1.

[0267] [Table 1]

[0268]

[0269] As shown in Table 1, for a laminate obtained by combining a green sheet, which is equivalent to a first structure containing inorganic particles such as aliphatic polycarbonate and ceramic particles, and a coating film, which is equivalent to a second structure containing inorganic particles such as branched polymers with a main chain formed by cellulose polymers and branched chains formed by aliphatic polycarbonate or aliphatic polyester and metal particles, it is not easily peeled off by external forces such as shear force during cutting or pressure of gas generated during firing.

Claims

1. A composite structure comprising a first structure and a second structure, The first structure is connected to the second structure. The first structure comprises aliphatic polycarbonate and a first inorganic particle. The second structure comprises a branched polymer and a second inorganic particle. The branched polymer has a main chain formed by a cellulose-based polymer and branches formed by aliphatic polycarbonate or aliphatic polyester. The branches are either straight chains or branched chains. Both the first structure and the second structure are sheet-like in shape, and the first structure and the second structure are stacked together. The first structure and the second structure are repeatedly and alternately stacked. The first structure comprises metal particles and ceramic particles as the first inorganic particles. The second structure comprises ceramic particles as the second inorganic particles, and optionally includes metal particles. In the first structure, the volume of the metal particles is larger than the volume of the ceramic particles. In the second structure, the volume of the ceramic particles is larger than the volume of the metal particles.

2. A composite structure comprising a first structure and a second structure, The first structure is connected to the second structure. The first structure comprises aliphatic polycarbonate and a first inorganic particle. The second structure comprises a branched polymer and a second inorganic particle. The branched polymer has a main chain formed by a cellulose-based polymer and branches formed by aliphatic polycarbonate or aliphatic polyester. The branches are either straight chains or branched chains. Both the first structure and the second structure are sheet-like in shape, and the first structure and the second structure are stacked together. The first structure and the second structure are repeatedly and alternately stacked. The first structure comprises ceramic particles as the first inorganic particles, and optionally includes metal particles. The second structure comprises metal particles and ceramic particles as the second inorganic particles. In the first structure, the volume of the ceramic particles is larger than the volume of the metal particles. In the second structure, the volume of the metal particles is larger than the volume of the ceramic particles.

3. The composite structure according to claim 1 or 2, wherein, The metal constituting the metal particles is at least one selected from Ni, Cu, Ag, Pt and Au.

4. The composite structure according to claim 1 or 2, wherein, The materials constituting the ceramic particles include at least one selected from Ba, Ti, Sr, Ca and Zr.

5. The composite structure according to claim 1 or 2, wherein, The cellulose-based polymer comprises at least one selected from methylcellulose, ethylcellulose, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate.

6. The composite structure according to claim 1 or 2, wherein, The molecular chain of the branched polymer has branches formed from the aliphatic polyester. The aliphatic polyester is selected from at least one of polycaprolactone, polylactic acid, poly(3-hydroxybutyric acid), and polybutylene succinate.

7. The composite structure according to claim 1 or 2, wherein, The first structure and the second structure each independently contain at least one additive selected from dispersants, plasticizers and antistatic agents.

8. The composite structure according to claim 1 or 2, wherein, The branch is bonded to two or more of the main chains to crosslink the two or more main chains.

9. The composite structure according to claim 1, wherein, The second structure may or may not contain additives. The content of ceramic particles in the second structure is 45% by volume or more and 70% by volume or less, relative to the total volume of the branched polymer, the volume of the second inorganic particles, and the volume of the additive contained in the second structure.

10. The composite structure according to claim 1, wherein, The first structure may or may not contain additives. The content of the metal particles in the first structure is 50% by volume or more and 75% by volume or less, relative to the total volume of the aliphatic polycarbonate, the volume of the first inorganic particles, and the volume of the additive contained in the first structure.

11. The composite structure according to claim 2, wherein, The first structure may or may not contain additives. The content of ceramic particles in the first structure is 45% by volume or more and 70% by volume or less, relative to the total volume of the aliphatic carbonate contained in the first structure, the volume of the first inorganic particles, and the volume of the additive.

12. The composite structure according to claim 2, wherein, The second structure may or may not contain additives. The content of the metal particles in the second structure is 50% by volume or more and 75% by volume or less, relative to the total volume of the branched polymer contained in the second structure, the volume of the second inorganic particles, and the volume of the additive.

13. A laminated ceramic electronic component precursor comprising the composite structure described in any one of claims 1 to 12.

14. A method for manufacturing a precursor of a laminated ceramic electronic component, comprising cutting the composite structure according to any one of claims 1 to 12 along a direction perpendicular or substantially perpendicular to the surface direction of the composite structure.

15. A method for manufacturing a laminated ceramic electronic component, comprising: The method of claim 14 is used to manufacture the laminated ceramic electronic component precursor, and The laminated ceramic electronic component precursor is sintered.

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