Electrically conductive paste, electronic component, and layered ceramic capacitor

Abstract

Provided are: an electrically conductive paste, utilizing an electrically conductive powder or a ceramic powder that has been refined to make a layered ceramic electronic component more compact and thinner, wherein the conductive paste can form an internal electrode layer that comprises a smooth dried film and has excellent adhesion; an electronic component; and a layered ceramic capacitor.　This electrically conductive paste includes an electrically conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent. The binder resin includes a polymer compound in which a cellulose-based compound and a polyvinyl acetal–based compound are bonded by sulfur atoms. The molar ratio of the sulfur atoms included in the polymer compound to the cellulose-based compound is 0.3–1.7, and the weight-average molecular weight of the polymer compound is at least 30,000 and less than 150,000.

Description

Conductive paste, electronic components and multilayer ceramic capacitors

[0001] The present invention relates to a conductive paste, an electronic component, and a multilayer ceramic capacitor.

[0002] As electronic devices such as mobile phones and digital devices become smaller and more powerful, there is a demand for smaller and higher-capacity electronic components, including multilayer ceramic capacitors. Multilayer ceramic capacitors have a structure in which multiple dielectric layers and multiple internal electrode layers are alternately stacked, and by reducing the thickness of these dielectric layers and internal electrode layers, it is possible to achieve smaller size and higher capacity.

[0003] For example, a multilayer ceramic capacitor is manufactured as follows: First, barium titanate (BaTiO ３ A conductive paste for internal electrodes is printed (applied) in a predetermined electrode pattern onto the surface of a green sheet containing a dielectric powder such as ethylenediaminetetraacetic acid (ETA) or propylene glycol (PEG) and a binder resin such as polybutyral resin (PVB), and then dried to form a dry film. Next, the dried film and the green sheet are alternately stacked and heat-pressed to form a laminate. This laminate is then cut, subjected to an organic binder removal process in an oxidizing or inert atmosphere, and then fired to obtain fired chips. Next, a paste for external electrodes is applied to both ends of the fired chip, and after firing, the external electrode surfaces are nickel-plated or otherwise treated to obtain multilayer ceramic capacitors (MLCCs). The conductive paste for internal electrodes contains a conductive powder such as nickel powder, a ceramic powder such as barium titanate powder, an organic binder, and a solvent.

[0004] In recent years, there has been a demand for MLCCs to be even smaller and have larger capacities, and for example, for internal electrodes using nickel or the like, efforts have been made to make the electrode film thinner, with excellent density and continuity, and for ceramic dielectric materials and dielectric layers using such materials, efforts have been made to make the dielectric layer thinner and with a higher dielectric constant, and dielectric layers with a thickness of 1.0 μm or less have already been put into practical use. It is also desirable for the electrode layer to have a thickness of 1.0 μm or less.

[0005] As the internal electrode layers become thinner, the surface of the electrode layers becomes more prone to unevenness, and it is said that the concentration of the electric field on the convex parts of the electrode layers reduces the insulation resistance of the dielectric layer, so there is a demand for further smoothing of the electrode layer surfaces.

[0006] Furthermore, when the MLCC is made thinner, the adhesion between the green sheets and the internal electrode layers decreases, and problems arise such as frequent peeling and lamination misalignment due to insufficient adhesion during lamination.

[0007] This poor adhesion can cause short circuits in multilayer ceramic capacitors, for example. In particular, the demand for multilayer MLCCs requires the use of fine-particle dielectric powder to reduce the thickness of each dielectric layer and increase the number of layers, making it desirable to improve the poor adhesion. Weak adhesion between green sheets can cause structural defects such as delamination, voids, and cracks during firing, reducing the yield of MLCCs.

[0008] To improve such poor adhesion, when stacking multiple ceramic green sheets with conductive paste films formed thereon, the surface of the coating film made of conductive paste is smoothed, thereby increasing the contact area between the conductive paste film and the ceramic green sheets, and as a result, improving adhesion.

[0009] For this reason, cellulose-based resins such as ethyl cellulose (EC) have been mainly used as organic binders, but cellulose-based resins are highly compatible with the various solvents used in conductive pastes, making it possible to impart the desired rheological properties to the conductive paste and are effective in smoothing the surface of the coating film made of conductive paste.On the other hand, cellulose-based resins do not have much thermoplasticity, so they have the characteristic that the dried film portion of the conductive paste does not adhere to the upper green sheet during thermocompression bonding.

[0010] Therefore, if a butyral resin is used as the binder resin in the conductive paste, the adhesion between the internal electrodes and the green sheets can be improved. Patent Document 1 discloses that it is preferable to use a mixture of ethyl cellulose and polyvinyl butyral as the organic binder resin in the internal electrode paste.

[0011] However, when the conductive paste for the internal electrodes contains polyvinyl butyral, the solvent used for the conductive paste must be capable of dissolving polyvinyl butyral. Therefore, the solvent in the conductive paste may also dissolve the polyvinyl butyral in the green sheet, resulting in sheet attack. Sheet attack can cause the green sheet to become locally thin or holes to form in the green sheet, resulting in poor formation of the internal electrodes or the disappearance of the green sheet between the internal electrodes, causing the internal electrodes to connect and resulting in a short circuit. In consideration of this, Patent Document 2 discloses a special solvent composition that can address sheet attack.

[0012] JP 2009-147359 A JP 2020-057691 A

[0013] Generally, when two organic binder resins with significantly different structures are mixed, the resulting combination is almost always incompatible. When two organic binder resins are incompatible, the two organic binder resins basically do not mix with each other and exist independently, so the expected performance may not be achieved by using the two organic binder resins, or the performance may be significantly reduced compared to when each organic binder is used alone.

[0014] Furthermore, when the resin becomes less soluble in the solvent, the smoothness of the dried conductive paste film deteriorates. For example, when ethyl cellulose and polyvinyl butyral are mixed, they are incompatible, resulting in a typical "sea-island structure" and phase separation. This results in an uneven distribution of inorganic particles (conductive particles, ceramic powder) in the dried film. In this way, the combination of organic materials in the paste composition affects the dispersibility of inorganic particles (conductive particles, ceramic powder) in the dried film.

[0015] If organic binder resins that are normally immiscible can be made to dissolve in each other, the advantages of both can be combined, the interface between the different polymers can be stabilized, and a uniform and stable dispersion state can be achieved.

[0016] Furthermore, the conductive pastes disclosed in Patent Documents 1 and 2 contain polyvinyl butyral resin, which can improve the adhesion between the dried film and the green sheet. However, the combined use of cellulose-based resin and polyvinyl butyral resin can result in poor compatibility between the two resins, which can lead to insufficient dispersion of the conductive powder and ceramic powder in the conductive paste, or in insufficient density and smoothness of the dried film of the conductive paste.

[0017] In view of the above circumstances, an object of the present invention is to provide a conductive paste using a finely divided conductive powder or ceramic powder for reducing the size and thickness of a multilayer ceramic electronic component, which is capable of forming an internal electrode layer having a smooth dried film and excellent adhesion, an electronic component, and a multilayer ceramic capacitor.

[0018] In order to solve the above problems, the conductive paste of the present invention comprises a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent, wherein the binder resin comprises a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded together via sulfur atoms, the molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight-average molecular weight of the polymer compound is 30,000 or more and less than 150,000.

[0019] The polymer compound may have a weight average molecular weight of 60,000 or more and 130,000 or less.

[0020] The cellulose compound may be a cellulose derivative having a thiol group or a vinyl group, the polyvinyl acetal compound may be a polyvinyl acetal resin having a thiol group or a vinyl group, and if the cellulose derivative has a thiol group, the polyvinyl acetal resin may have a vinyl group that reacts with the thiol group, and if the cellulose derivative has a vinyl group, the polyvinyl acetal resin may have a thiol group that reacts with the vinyl group.

[0021] The cellulose derivative may be ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin may be polyvinyl butyral having a thiol group or a vinyl group.

[0022] The cellulose-based compound may be a first esterification reaction product obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group with a hydroxyl group of cellulose; the polyvinyl acetal-based compound may be a second esterification reaction product obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group with a hydroxyl group of polyvinyl acetal; if the first esterification reaction product has a thiol group, the second esterification reaction product may have a vinyl group; if the first esterification reaction product has a vinyl group, the second esterification reaction product may have a thiol group; and the polymer compound may be a thiol-ene reaction product of the first esterification reaction product and the second esterification reaction product.

[0023] The first esterification reaction product may be an esterification reaction product obtained by dehydration condensation of a carboxy group of 3-allyloxypropionic acid and a hydroxy group of ethyl cellulose, and the second esterification reaction product may be an esterification reaction product obtained by dehydration condensation of a carboxy group of 3-mercaptopropionic acid and a hydroxy group of polyvinyl butyral.

[0024] The binder resin may contain at least one of cellulose and polyvinyl acetal.

[0025] The conductive powder may be nickel powder.

[0026] The number average particle size of the conductive powder may be 0.05 μm or more and 0.3 μm or less.

[0027] The ceramic powder may include barium titanate.

[0028] The ceramic powder may have a number average particle size of 0.01 μm or more and 0.5 μm or less.

[0029] The content of the ceramic powder may be 1% by mass or more and 20% by mass or less.

[0030] The conductive paste of the present invention may be used for internal electrodes of multilayer ceramic components.

[0031] In order to solve the above-mentioned problems, the electronic component of the present invention is an electronic component formed using the conductive paste of the present invention.

[0032] In order to solve the above-mentioned problems, the multilayer ceramic capacitor of the present invention is a multilayer ceramic capacitor having at least a laminate in which dielectric layers and internal electrode layers are laminated, and the internal electrode layers are formed using the conductive paste of the present invention.

[0033] The conductive paste of the present invention has excellent dispersibility of the conductive powder and a high surface smoothness when dried after application. Furthermore, the electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of the present invention has excellent adhesion of the conductive paste even when forming a thin electrode.

[0034] 1A and 1B are perspective and cross-sectional views of the multilayer ceramic capacitor according to the present embodiment.

[0035] Hereinafter, an embodiment of the conductive paste, electronic component, and multilayer ceramic capacitor of the present invention will be described.

[0036] [Conductive Paste] The conductive paste of this embodiment contains a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent. Each component will be described in detail below.

[0037] (Conductive Powder) The conductive powder is not particularly limited, and metal powders can be used. For example, powders of one or more elements selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, powders of Ni or its alloys are preferred from the viewpoints of conductivity, corrosion resistance, and cost. Examples of Ni alloys that can be used include alloys of Ni with at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd (Ni alloys). The Ni content in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. Furthermore, the Ni powder may contain several hundred ppm of S to suppress rapid gas generation due to partial thermal decomposition of the binder resin during binder removal treatment.

[0038] The method for producing the conductive powder is not particularly limited, and examples thereof include a method in which chloride vapor is directly precipitated from the gas phase in hydrogen gas, an atomization method from molten metal, a spray pyrolysis method using an aqueous solution, and a wet method in which a raw material metal salt is reduced in an aqueous solution.

[0039] The number average particle size of the conductive powder is not particularly limited and may be selected depending on the size of the electronic component to be used. For example, for multilayer ceramic capacitors, which are becoming thinner, the number average particle size of the conductive powder is preferably 0.3 μm or less, and more preferably 0.2 μm or less. An average particle size exceeding 0.3 μm is undesirable because it can cause significant unevenness on the internal electrode surface and degrade the electrical characteristics of the capacitor. The lower limit of the average particle size of the conductive powder is not particularly limited, but is, for example, 0.05 μm or more. A number average particle size smaller than 0.05 μm can make handling extremely difficult.

[0040] The number average particle size of the conductive powder is a value determined by observation using a scanning electron microscope (SEM), and is the average value obtained by measuring the particle size of each of multiple particles from an image observed with an SEM at a magnification of 10,000 times.

[0041] The content of the conductive powder is preferably 30% by mass or more and less than 70% by mass, more preferably 40% by mass or more and less than 60% by mass, based on the total amount of the conductive paste. When the content of the conductive powder is 30% by mass or more and less than 70% by mass, based on the total amount of the conductive paste, the conductive paste has excellent conductivity and dispersibility.

[0042] (Ceramic Powder) The ceramic powder is not particularly limited, and for example, in the case of a conductive paste for an internal electrode of a multilayer ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of multilayer ceramic capacitor to be applied. Examples of the ceramic powder include perovskite-type oxides containing Ba and Ti, and preferably barium titanate (BaTiO ３ )

[0043] The ceramic powder may be a ceramic powder containing barium titanate as a main component and an oxide as a secondary component. Examples of the oxide include oxides of Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and one or more rare earth elements. Examples of the ceramic powder include barium titanate (BaTiO ３ Alternatively, a ceramic powder of a perovskite-type oxide ferroelectric may be used in which the Ba atoms or Ti atoms of the above-mentioned alloy are substituted with other atoms such as Sn, Pb, or Zr.

[0044] In the conductive paste for the internal electrodes, powder of the same composition as the dielectric ceramic powder constituting the green sheets of the multilayer ceramic capacitor may be used as the ceramic powder. This suppresses the occurrence of cracks due to a mismatch in shrinkage at the interface between the dielectric layer and the internal electrode layer during the sintering process. In addition to the above, examples of such ceramic powders include ZnO, ferrite, PZT, BaO, and Al. ２ O ３ , Bi ２ O ３ , R (rare earth element) ２ O ３ , TiO ２ , Nd ２ O ３ The ceramic powder may be one type or two or more types.

[0045] The number average particle diameter of the ceramic powder is, for example, 0.01 μm or more and 0.5 μm or less, preferably 0.01 μm or more and 0.3 μm or less. When the ceramic powder has a number average particle diameter of 0.01 μm or more and 0.5 μm or less, when used as an internal electrode paste, a sufficiently fine, thin, and uniform internal electrode can be formed. The number average particle diameter is a value determined by observation with a scanning electron microscope (SEM), and is the average value obtained by measuring the particle diameter of each of a plurality of particles in an image observed with the SEM at a magnification of 50,000 times.

[0046] The content of the ceramic powder is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the conductive powder. When the content of the conductive powder is 1 part by mass or more and 30 parts by mass or less, the conductivity and dispersibility are excellent.

[0047] The content of the ceramic powder is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 20% by mass or less, based on the total amount of the conductive paste. When the content of the ceramic powder is 1% by mass or more and 20% by mass or less, the conductive paste has excellent conductivity and dispersibility.

[0048] (Binder Resin) The binder resin used in the conductive paste of this embodiment contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by sulfur atoms, the molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight-average molecular weight (Mw) of the polymer compound is 30,000 or more and less than 150,000.

[0049] That is, the binder resin used in the conductive paste of this embodiment contains a polymer compound in which a cellulose compound and a polyvinyl acetal compound are bonded. Because the polymer compound molecule contains a portion due to the cellulose compound and a portion due to the polyvinyl acetal compound, the dried film obtained from the conductive paste of this embodiment can have the surface smoothness due to the cellulose compound and the adhesion to the green sheet due to the polyvinyl acetal compound. Furthermore, by having the structures of the cellulose compound and the polyvinyl acetal compound, which are incompatible with each other, in the same molecule, the polymer compound can also eliminate poor dispersion of the conductive paste.

[0050] The weight average molecular weight (Mw) of the polymer compound used in the present invention is preferably 30,000 or more and less than 150,000, more preferably 60,000 or more and 130,000 or less, as calculated using standard polystyrene standards by gel permeation chromatography (GPC).

[0051] If the weight-average molecular weight of the polymeric molecular compound is 30,000 or more, the desired viscosity can be obtained, and if it is less than 150,000, poor dispersion due to steric hindrance can be suppressed, and the surface roughness of the dried film can be smoothed when the conductive paste is printed.

[0052] Furthermore, if the molecular weight of the polymer compound is small, the viscosity of the polymer compound tends to decrease, so that the amount of resin blended into the conductive paste can be increased, thereby improving adhesion. Furthermore, even when a conductive powder with a small particle size is used, there is an effect of suppressing an increase in the viscosity of the conductive paste.

[0053] The content of the polymer compound in which a cellulose compound and a polyvinyl acetal compound are bonded is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, per 100 parts by mass of the conductive powder. When the content of the polymer compound is 1 part by mass or more per 100 parts by mass of the conductive powder, the rheological properties of the cellulose compound and the adhesive properties of the polyvinyl acetal compound are exhibited, and dispersibility is also excellent. Furthermore, when the content of the polymer compound is more than 10 parts by mass, when the dried film of the conductive paste is sintered, carbon originating from the polymer compound may gasify, causing delamination or reducing adhesion to the green sheet.

[0054] The polymer compound molecules of this embodiment contain both cellulose-based and polyvinyl acetal-based compounds, so that the dried film obtained from the conductive paste of this embodiment can have the surface smoothness due to the cellulose-based compound and the adhesion to the green sheet due to the polyvinyl acetal-based compound. Furthermore, by having the structures of the cellulose-based compound and the polyvinyl acetal-based compound, which are incompatible with each other, in the same molecule, the polymer compound can also eliminate the poor dispersion of the conductive paste that occurs when a cellulose-based compound and a polyvinyl acetal-based compound are mixed and used.

[0055] Furthermore, when the molar ratio of sulfur atoms contained in the polymer compound to the cellulose compound is 0.3 to 1.7, i.e., cellulose compound:sulfur atom=1.0:0.3 to 1.7, the surface roughness and density of the dried film are even better than those of a conductive paste made of a conventional binder resin that uses a cellulose compound and a polyvinyl acetal compound in combination. A more preferred range of this molar ratio is 0.5 to 1.5.

[0056] If the molar ratio of sulfur atoms contained in the polymer compound to the cellulose compound is 0.3 or more, the amount of unreacted cellulose compound and polyvinyl acetal compound is reduced, thereby enabling the polymer compound to exhibit its effects. Furthermore, if the molar ratio is 1.7 or less, the number of bonding sites between the cellulose compound and the polyvinyl acetal compound in the polymer compound does not increase more than necessary, thereby preventing deterioration in the fluidity of the conductive paste and reducing the surface roughness of the dried film produced from the conductive paste.

[0057] The polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded, which can be used in this embodiment, will be described in more detail.

[0058] Both cellulose and polyvinyl acetal have hydroxyl groups in their molecules. Cellulose-based compounds have functional groups introduced into the hydroxyl groups of cellulose that can react with other compounds to form bonds. On the other hand, polyvinyl acetal-based compounds have functional groups introduced into the hydroxyl groups of polyvinyl acetal that can react with other compounds to form bonds and that are different from the functional groups introduced into the cellulose-based compounds. In other words, the reactive functional groups introduced into cellulose-based compounds and the reactive functional groups introduced into polyvinyl acetal-based compounds are different. Note that while the functional groups introduced into cellulose-based compounds and the functional groups introduced into polyvinyl acetal-based compounds react, the same functional groups do not react easily. Here, the reason why the same functional groups do not react easily is to avoid bonding between cellulose-based compounds and polyvinyl acetal-based compounds.

[0059] Then, by bonding the functional group introduced into the cellulose-based compound with the functional group introduced into the polyvinyl acetal-based compound, a polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded can be obtained. Specifically, by introducing a thiol group into cellulose to form a cellulose-based compound and a vinyl group into a polyvinyl acetal resin to form a polyvinyl acetal-based compound, the thiol group and the vinyl group bond via the double bond of the vinyl group and the sulfur atom of the thiol group in the presence of a nucleophile or under conditions that generate radicals. As the polymer compound of the binder resin used in the conductive paste of this embodiment, a polymer compound in which the cellulose-based compound and the polyvinyl acetal-based compound are bonded can be obtained by utilizing the bonding reaction between the thiol group and the vinyl group. Of course, it is also possible to introduce a vinyl group into the hydroxyl group of cellulose to form a cellulose-based compound, and then introduce a thiol group into the hydroxyl group of the polyvinyl acetal resin to form a polyvinyl acetal-based compound.

[0060] That is, the cellulose compound may be a cellulose derivative having a thiol group or a vinyl group, and the polyvinyl acetal compound may be a polyvinyl acetal resin having a thiol group or a vinyl group. When the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group, and when the cellulose derivative has a vinyl group, the polyvinyl acetal resin has a thiol group that reacts with the vinyl group.

[0061] The cellulose-based polymer compound used as the binder resin of the conductive paste of this embodiment is preferably a polymer compound chemically modified by bonding a compound to a hydroxyl group possessed by cellulose, a natural polymer. Note that this chemical modification is different from the chemical modification that introduces a reactive functional group described above, and is a chemical modification for the following alkyl etherification, esterification, etc.

[0062] Examples of bonding of a compound with the hydroxyl group of cellulose include alkyl etherification and esterification. Examples of celluloses having hydroxyl groups include methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, cellulose acetate (acetyl cellulose, diacetyl cellulose, triacetyl cellulose, etc.), cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, etc. Only one of these celluloses may be used, or two or more may be used in combination.

[0063] Since the conductive paste of the present embodiment contains an organic solvent, it is preferable that the cellulose also dissolves in the organic solvent. From the viewpoints of solubility in the organic solvent and smoothness of the dried film of the conductive paste, it is more preferable to use ethyl cellulose as the cellulose.

[0064] The molecular weight of the cellulose used as the polymer compound affects the viscosity of the conductive paste of this embodiment. The weight average molecular weight (Mw) of the cellulose, as calculated using standard polystyrene standards by GPC, is preferably 20,000 to 250,000, and more preferably 50,000 to 220,000.

[0065] If the weight-average molecular weight of cellulose is less than 20,000, the viscosity of the conductive paste may be low, while if the weight-average molecular weight of cellulose is more than 250,000, the viscosity of the conductive paste may be too high. Furthermore, the weight-average molecular weight of the polymer compound can be controlled by the amount of radical initiator added when synthesizing the cellulose compound and the polyvinyl acetal compound. For example, increasing the amount of radical initiator breaks the molecular bonds of the cellulose compound or polyvinyl acetal compound, thereby lowering the molecular weight. Therefore, the weight-average molecular weight of the polymer compound can be controlled to a desired value by adjusting the weight-average molecular weight of the cellulose compound or polyvinyl acetal compound used and the amount of radical initiator added.

[0066] Not all of the hydroxyl groups in cellulose are chemically modified. Before chemical modification, cellulose has three hydroxyl groups per cyclic structure of the glucose ring that makes up the cellulose. However, after chemical modification, on average, 0.1 to 1 hydroxyl group per cyclic structure of the glucose ring that makes up the cellulose remains as a hydroxyl group and is not chemically modified. In the present invention, reactive functional groups are introduced into these unmodified hydroxyl groups.

[0067] On the other hand, polyvinyl acetal is usually a polymer composed of vinyl acetal / vinyl alcohol / vinyl acetate monomer units, and can be obtained by saponifying polyvinyl acetate to polyvinyl alcohol and then acetalizing the polyvinyl alcohol.Specific examples of polyvinyl acetal include butyralized polyvinyl alcohol (polyvinyl butyral) and formalized polyvinyl alcohol (polyvinyl formal).

[0068] The polyvinyl acetal may be a commercially available product, and various polyvinyl acetals differing in the degree of butyralization, degree of formalization, amount of acetyl groups, amount of hydroxyl groups, molecular weight, etc. are sold by Sekisui Chemical Co., Ltd., Kuraray Co., Ltd., etc. Only one type of polyvinyl acetal may be used, or two or more types may be used in combination.

[0069] The polyvinyl acetal is preferably one that is soluble in an organic solvent, and more preferably polyvinyl butyral because of its high solubility in an organic solvent.

[0070] The molecular weight of polyvinyl acetal used as a polymer compound affects the film strength and the viscosity of the solution. Therefore, the weight-average molecular weight of polyvinyl acetal is preferably in the range of 10,000 to 300,000, and more preferably in the range of 20,000 to 250,000, as calculated using standard polystyrene standards by GPC.

[0071] If the weight-average molecular weight of the polyvinyl acetal is less than 10,000, the solution viscosity will be extremely low, making it difficult to adjust the viscosity of the inorganic particle-containing composition (paste or slurry). Furthermore, the strength and adhesion of the film formed by applying and drying the inorganic particle-containing composition may be reduced. Furthermore, if the weight-average molecular weight of the polyvinyl acetal exceeds 300,000, the viscosity of the conductive paste will be too high, resulting in poor dispersibility of the conductive powder. Furthermore, the weight-average molecular weight of the polymer compound can be controlled by the amount of radical initiator added when synthesizing a cellulose-based compound and a polyvinyl acetal-based compound. For example, increasing the amount of radical initiator breaks the molecular bonds of the cellulose-based compound or polyvinyl acetal-based compound, thereby lowering the molecular weight. Therefore, the weight-average molecular weight of the polymer compound can be controlled to the desired value by adjusting the weight-average molecular weight of the cellulose-based compound or polyvinyl acetal-based compound used and the amount of radical initiator added.

[0072] Polyvinyl acetal has at least one hydroxyl group per molecule. Generally, polyvinyl acetal has 20 to 40 mol % of hydroxyl groups as vinyl alcohol units constituting the polymer. These hydroxyl groups are chemically modified by introducing reactive functional groups.

[0073] The compound that reacts with the hydroxyl groups of cellulose or polyvinyl acetal to chemically modify it can be a compound that has a thiol or vinyl group at one end and a carboxyl group at the other end, and the carboxyl group of the compound undergoes dehydration condensation with the hydroxyl groups of the cellulose-based polymer compound or polyvinyl acetal compound to form an ester bond.

[0074] (Method for Synthesizing Polymer Compounds) An example of a method for synthesizing the polymer compounds used in this embodiment will be described below. Cellulose-based compounds and polyvinyl acetal-based compounds can be obtained by esterifying or etherifying the hydroxyl groups of cellulose or polyvinyl acetal with a compound having a functional group reactive with a hydroxyl group and a functional group reactive with other compounds. Examples of functional groups reactive with hydroxyl groups include carboxyl groups and hydroxyl groups.

[0075] The esterification reaction can be carried out using, for example, a condensing agent. Examples of the condensing agent include carbodiimide, diphenylphosphoric acid azide, and 1-hydroxybenzotriazole. One type of condensing agent may be used alone, or two or more types may be used in combination. Among these, carbodiimide is preferred because it has excellent versatility and reactivity and allows the reaction to proceed under low temperature conditions and without being affected by moisture in the reaction environment.

[0076] Examples of carbodiimides include dicyclohexylcarbodiimide, diisopropylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide, and N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methiodide. Among these, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferred from the viewpoint of availability. When using a carbodiimide, it is also preferred to use a base such as dimethylaminopyridine or triethylamine as a reaction accelerator in the range of 0.01 mol % to 10 mol % relative to the carbodiimide.

[0077] On the other hand, the etherification reaction can be carried out efficiently by using an alkali metal hydroxide such as KOH or NaOH, or an alkali metal hydride such as NaH or KH as a reaction catalyst.

[0078] To obtain a cellulose-based compound, it is also preferable to dissolve cellulose in an aprotic solvent such as ethyl acetate, mix with a compound having a carboxyl group that forms an ester bond with a hydroxyl group and a vinyl group or a thiol group that is a functional group that reacts with other compounds, and use a condensing agent and a base such as dimethylaminopyridine as a nucleophile to promote the esterification reaction in the range of 0.01 mol % to 10 mol %.

[0079] The polymer compound used in this embodiment has a molar ratio of sulfur atoms to the cellulose-based compound of 0.3 to 1.7. Therefore, it is necessary to add 0.3 to 1.7 mol of a compound having a functional group that reacts with other compounds per 1 mol of cellulose.

[0080] The reaction temperature for synthesizing a cellulose-based compound is preferably in the range of room temperature to 50°C. In a system where the synthesis reaction of a cellulose-based compound is completed, a mixture of unreacted cellulose, in which no functional group reactive with other compounds has been introduced to the hydroxyl group, a cellulose-based compound in which one reactive functional group has been introduced, and a cellulose-based compound in which multiple reactive functional groups have been introduced, is present. Chemical modification is a matter of probability, but the majority of cellulose-based compounds have one hydroxyl group of cellulose chemically modified. In the present invention, the mixture of unreacted cellulose, cellulose in which multiple functional groups have been introduced, and cellulose in which one reactive functional group has been introduced is referred to as the cellulose-based compound. Then, once the synthesis of the cellulose-based compound is completed, the solvent can be removed by distillation.

[0081] To synthesize a polyvinyl acetal compound, it is preferable to dissolve polyvinyl acetal in an aprotic solvent such as ethyl acetate, mix it with a compound having a carboxy group that forms an ester bond with a hydroxyl group and a vinyl group or a thiol group that is a functional group that reacts with other compounds, and use a condensing agent and a base such as dimethylaminopyridine as a nucleophile to promote the esterification reaction in the range of 0.01 mol % to 10 mol %.

[0082] The reaction temperature for chemically modifying the hydroxyl groups of polyvinyl acetal is preferably in the range of room temperature to 50°C. Although a functional group such as a thiol group or a vinyl group is introduced into the polyvinyl acetal, the functional group is not necessarily introduced into all of the polyvinyl acetal, and unreacted polyvinyl acetal is present. In the present invention, a mixture of the unreacted polyvinyl acetal and the polyvinyl acetal into which the functional group has been introduced is used as the polyvinyl acetal compound. After the synthesis of the polyvinyl acetal compound is completed, the solvent can be removed by distillation.

[0083] The polymer compound used in this embodiment is synthesized by dissolving a cellulose-based compound and a polyvinyl acetal-based compound in an organic solvent, adding a radical initiator, and heating the mixture, causing a vinyl group in either the cellulose-based compound or the polyvinyl acetal-based compound to react with a thiol group in the other, resulting in bonding of the cellulose-based compound and the polyvinyl acetal-based compound.

[0084] Examples of the radical initiator include azo compounds such as 2,2'-azobisisobutyronitrile (AIBN), 3-carboxypropionitrile, azobismalenonitrile, and dimethyl-(2,2')-azobis(2-methylpropionate); organic peroxides such as benzoyl peroxide, lauroyl peroxide, and potassium persulfate; and alkylphenone compounds such as a 1:1 mass ratio mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-1-(4-(2-(2-hydroxyethoxy)ethoxy)phenyl)-2-methylpropan-1-one.

[0085] Alternatively, a polymer compound may be synthesized by dissolving a cellulose compound and a polyvinyl acetal compound in a solvent, adding a nucleophilic agent such as a base such as an amine, and heating the mixture to bond the cellulose compound and the polyvinyl acetal compound.

[0086] In this case, the temperature of the reaction for bonding the cellulose compound and the polyvinyl acetal compound can be appropriately selected, but is preferably 60° C. or higher, for example.

[0087] Examples of the solvent that can be used include acetate-based solvents such as dihydroterpineol acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, and isobornyl isobutyrate, which are solvents that can be used in conductive pastes, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, and butyl carbitol acetate, and terpene-based solvents such as terpineol and dihydroterpineol. If a solvent used in conductive pastes is used as the solvent, the dissolved polymer compound obtained after synthesis can be used directly as a vehicle, which is a raw material used in the conductive paste.

[0088] In this embodiment, in addition to the polymer compound in which a cellulose compound and a polyvinyl acetal compound are bonded, cellulose resins such as methyl cellulose, ethyl cellulose, ethylhydroxyethyl cellulose, and nitrocellulose, acrylic resins, and polyvinyl acetal resins such as polyvinyl butyral resins can also be added. One or more of the above resins may be used. In particular, in the present invention, it is preferable to use ethyl cellulose or polyvinyl butyral, which are used in the polymer compound. The molecular weight of the resin that can be added in this way is 10,000 or more and 250,000 or less, more preferably 30,000 or more and 200,000 or less, which is the same as that of the polymer compound as measured by GPC.

[0089] Generally, cellulose-based resins and polyvinyl acetal-based resins are not compatible with each other. However, the polymer compound can help the cellulose-based resin and polyvinyl acetal-based resin to be compatible with each other and suppress phase separation between the cellulose-based resin and the polyvinyl acetal-based resin. Furthermore, because the polymer compound can help the cellulose-based resin and the polyvinyl acetal-based resin to be compatible with each other, even if a solvent that dissolves the cellulose-based resin more easily than the polyvinyl acetal-based resin is used as a conductive paste, the polymer compound coexists with the polyvinyl acetal-based resin, thereby exhibiting the effect of dissolving the polyvinyl acetal-based resin. These effects are due to the polymer compound having a cellulose compound skeleton and a polyacetal compound skeleton in its molecule.

[0090] In the conductive paste of this embodiment, the proportion of the polymer compound relative to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and polymer compound in the binder resin is 20% by mass or more, and preferably 30% by mass or more. If the proportion of the polymer compound relative to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and polymer compound is less than 20% by mass, the suppression of phase separation may be limited to a portion of the conductive paste, resulting in unsatisfactory results. The proportion of the polymer compound relative to the total mass of the cellulose-based resin, polyvinyl acetal-based resin, and polymer compound in the binder resin may be 99% by mass or less, or 95% by mass or less.

[0091] When this phase separation occurs, the dried film obtained by printing (applying) and drying the conductive paste contains unevenly distributed binder resin, conductive powder, and ceramic powder. The internal electrode obtained by firing the dried film may contain voids where no conductive material exists due to the uneven distribution of binder resin and ceramic powder. When voids form in the internal electrode, the area of ​​the internal electrode decreases, leading to a decrease in the capacity of the MLCC. The effect of the polymer compound in suppressing phase separation between the cellulose resin and the polyvinyl acetal resin contributes to a uniform particle distribution in the dried film. As a result, the film breakage phenomenon of the electrode layer after firing is resolved, increasing the capacity of the MLCC.

[0092] The content of the binder resin is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 6% by mass or less, based on the total amount of the conductive paste. When the content of the binder resin is 0.5% by mass or more and 10% by mass or less, the conductive paste has excellent conductivity and dispersibility.

[0093] For example, the cellulose derivative may be ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin may be polyvinyl butyral having a thiol group or a vinyl group.

[0094] Specifically, the cellulose-based compound may be a first esterification reaction product obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group with a hydroxyl group of cellulose, and the polyvinyl acetal-based compound may be a second esterification reaction product obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group with a hydroxyl group of polyvinyl acetal. Furthermore, when the first esterification reaction product has a thiol group, the second esterification reaction product may have a vinyl group; when the first esterification reaction product has a vinyl group, the second esterification reaction product may have a thiol group; and the polymer compound may be a thiol-ene reaction product of the first esterification reaction product and the second esterification reaction product.

[0095] More specifically, the first esterification reaction product may be an esterification reaction product obtained by dehydration condensation of a carboxy group of 3-allyloxypropionic acid and a hydroxy group of ethyl cellulose, and the second esterification reaction product may be an esterification reaction product obtained by dehydration condensation of a carboxy group of 3-mercaptopropionic acid and a hydroxy group of polyvinyl butyral.

[0096] (Organic Solvent) The organic solvent is not particularly limited, and any known organic solvent capable of dissolving the binder resin can be used. Examples of organic solvents include acetate-based solvents such as dihydroterpineol acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl ether acetate, and butyl carbitol acetate; terpene-based solvents such as terpineol and dihydroterpineol; hydrocarbon-based solvents such as tridecane, nonane, and cyclohexane; and petroleum-based hydrocarbon solvents such as mineral spirits. One or more organic solvents may be used. The solvent selection also takes into account compatibility with the ceramic green sheet.

[0097] The content of the organic solvent is preferably 40 parts by mass or more and 100 parts by mass or less, more preferably 65 parts by mass or more and 95 parts by mass or less, relative to 100 parts by mass of the conductive powder. When the content of the organic solvent is 40 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the conductive powder, the conductivity and dispersibility are excellent.

[0098] The content of the organic solvent is preferably 20% by mass or more and 60% by mass or less, and more preferably 35% by mass or more and 55% by mass or less, based on the total amount of the conductive paste. When the content of the organic solvent is 20% by mass or more and 60% by mass or less, based on the total amount of the conductive paste, the conductive paste has excellent conductivity and dispersibility.

[0099] (Dispersant) The conductive paste of this embodiment may contain a dispersant. The role of the dispersant is to adsorb to the surface of the inorganic powder (conductive powder and ceramic powder) to suppress aggregation of the inorganic powders and to improve wettability with the organic vehicle, thereby dispersing the inorganic powders in the conductive paste. The dispersant (surfactant) may include an acid-based dispersant including a higher fatty acid, a polymer surfactant, etc., a cationic dispersant other than an acid-based dispersant, a nonionic dispersant, an amphoteric surfactant, a polymer dispersant, etc.

[0100] Furthermore, one or more dispersants may be selected, and the content of the conductive paste may be selected appropriately taking into consideration the viscosity, stickiness, long-term storage stability, etc. of the conductive paste, and may be contained within a range that does not impair the effects of the present invention.

[0101] The mass-average molecular weight of the dispersant is preferably 200 to 100,000. It is more preferably 300 to 30,000. If the mass-average molecular weight is less than 200, the particles may not exhibit sufficient electrostatic repulsion, resulting in reduced particle dispersibility and storage stability. Typically, the dispersant adsorbs to the particle surface to form an adsorption layer, imparting electrostatic and steric repulsion to the particles, resulting in a paste with excellent dispersibility. However, it is believed that over time, collisions between particles overcome the repulsive force of the adsorption layer, causing the particles to aggregate. Therefore, a mass-average molecular weight of 200 or more is preferable. Furthermore, if the mass-average molecular weight is greater than 100,000, compatibility with organic vehicles and organic solvents may decrease, particles may aggregate, and dispersibility and storage stability may decrease. Furthermore, the conductive paste may have an increased viscosity.

[0102] The amount of dispersant added is preferably 0.01 to 5.00 parts by mass, more preferably 0.20 to 2.00 parts by mass, per 100 parts by mass of the conductive metal powder. If the amount of dispersant is less than 0.01 part by mass, it tends to be difficult to obtain sufficient dispersibility. On the other hand, if the amount of dispersant exceeds 5.00 parts by mass, the drying property may be poor and problems such as a decrease in the dry film density may occur.

[0103] The polymer dispersant is preferably anionic and has a carboxyl group or a carboxylic anhydride group. By using an anionic polymer dispersant, the dispersibility of inorganic powders such as conductive powders and ceramic powders in an organic vehicle can be further improved. Here, a carboxylic anhydride group is a group formed by the bonding of two carboxyl groups to H. ２ This refers to the anhydride state where O is dehydrated. Examples include acid anhydrides such as phthalic anhydride and maleic anhydride, which are molecular units composed of two dehydrated carboxyl groups.

[0104] Anionic polymer dispersants preferably have graft chains, which are expected to improve solubility in various organic solvents.

[0105] The mass average molecular weight of the anionic polymer dispersant is preferably 1,000 to 100,000, more preferably 5,000 to 70,000, and even more preferably 10,000 to 60,000. By making the mass average molecular weight of the polymer dispersant 1,000 or more, the dispersibility of the inorganic powder in the organic vehicle can be improved. If the mass average molecular weight is greater than 100,000, the compatibility with the organic vehicle and organic solvent may decrease, particles such as conductive powder and ceramic powder may aggregate, and the dispersibility and storage stability may decrease.

[0106] Such polymer dispersants have carboxyl groups or carboxylic anhydride groups as functional groups on the main chain, and anionic polymer dispersants preferably further have oxyethylene groups on the graft chains in order to adsorb inorganic powders.

[0107] The anionic polymer dispersant may contain one or more types. That is, multiple types of polymer dispersants may be contained depending on the length of the main chain, the length of the graft chain, the presence or absence of the graft chain, etc. The content of the anionic polymer dispersant in the conductive paste can be appropriately selected taking into consideration the viscosity, stickiness, long-term storage stability, etc. of the conductive paste, and may be contained within a range that does not impair the effects of the present invention.

[0108] Furthermore, the conductive paste of this embodiment may contain a dispersant other than the anionic polymer dispersant. For example, the dispersant (surfactant) may include an acid dispersant including a higher fatty acid, phosphoric acid, a polymer surfactant, etc., a cationic dispersant other than the acid dispersant, a nonionic dispersant, an amphoteric surfactant, a polymer dispersant, etc.

[0109] The content of the dispersant in the conductive paste can be appropriately selected taking into consideration the viscosity, stickiness, long-term storage stability, etc. of the conductive paste, and may be contained within a range that does not impair the effects of the present invention.

[0110] Furthermore, for both anionic polymer dispersants and other dispersants, the mass-average molecular weight of the dispersant is preferably 200 to 100,000. It is more preferably 300 to 30,000. A mass-average molecular weight less than 200 may result in reduced particle dispersibility and storage stability. Typically, a paste with excellent dispersibility is obtained by adsorbing the dispersant to the particle surface to form a dispersant adsorption layer, imparting electrostatic and steric repulsion to the particles. However, it is believed that over time, collisions between particles cause the cohesive forces of the particles to outweigh the repulsive forces of the adsorption layer, resulting in aggregation of the particles. Therefore, a mass-average molecular weight of 200 or greater is preferable. Furthermore, a mass-average molecular weight greater than 100,000 may result in reduced compatibility with organic vehicles and organic solvents, particle aggregation, and reduced dispersibility and storage stability. Furthermore, the paste may have an increased viscosity.

[0111] The total amount of the anionic polymer dispersant and other dispersants added is preferably 0.01 to 5.00 parts by mass, and more preferably 0.20 to 2.00 parts by mass, per 100 parts by mass of the conductive metal powder. If the amount of dispersant is less than 0.01 part by mass, it tends to be difficult to obtain sufficient dispersibility. On the other hand, if the amount exceeds 5.00 parts by mass, the drying property may be poor and problems such as a decrease in the dry film density may occur.

[0112] (Other Additives) The conductive paste may contain additives such as plasticizers, if necessary, in order to impart flexibility to the printed electrode layer.

[0113] (Method for Producing Conductive Paste) The method for producing the conductive paste of this embodiment is not particularly limited, and conventionally known methods can be used. The conductive paste can be produced, for example, by preparing the above-mentioned components and stirring and kneading them using a triple-roll mill, a ball mill, a mixer, or the like. In this case, if a dispersant is applied to the surface of the conductive powder in advance, the conductive powder is sufficiently loosened without agglomeration, allowing the dispersant to be distributed evenly across the surface, making it easier to obtain a uniform conductive paste. Alternatively, the binder resin may be dissolved in an organic solvent for the vehicle to produce an organic vehicle, and the conductive powder, ceramic powder, organic vehicle, and dispersant may be added to the organic solvent for the paste, followed by stirring and kneading using a mixer to produce the conductive paste.

[0114] In addition, the organic solvent for the vehicle is preferably the same as the organic solvent for the paste that adjusts the viscosity of the conductive paste, in order to improve the compatibility of the organic vehicle. The content of the organic solvent for the vehicle is, for example, 5 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of the conductive powder. The content of the organic solvent for the vehicle is preferably 10% by mass or more and 40% by mass or less relative to the total amount of the conductive paste.

[0115] The surface smoothness of a dry film formed by printing a conductive paste can be evaluated by its surface roughness. The surface roughness of the conductive paste can be measured, for example, by the method described in the Examples (a method of measuring the arithmetic mean height Sa based on ISO 25178 using an OLS-5000 manufactured by Evident). When the surface smoothness of the dry film is evaluated by the arithmetic mean height Sa, the value is preferably 55 nm or less. If the arithmetic mean height Sa is 55 nm or less, even if the dielectric layer is thinned (for example, 1.0 μm or less), it is possible to prevent the electric field from concentrating on the convex portions of the electrode layer due to the unevenness of the internal electrode layer, thereby preventing a decrease in the insulation resistance of the dielectric layer.

[0116] Furthermore, in consideration of the manufacturing process of the multilayer ceramic capacitor, if the surface roughness of the dried conductive paste film is low, the dried conductive paste film adheres to the green sheet as a surface, and the adhesion between the dried conductive paste film and the green sheet is excellent. Therefore, it is desirable that the surface roughness of the dried conductive paste film is as low as possible.

[0117] [Electronic Components, Multilayer Ceramic Capacitors] The conductive paste of the present invention can be suitably used in electronic components such as multilayer ceramic capacitors. The multilayer ceramic capacitor has dielectric layers formed using green sheets and internal electrode layers formed using the conductive paste.

[0118] In the multilayer ceramic capacitor, it is preferable that the dielectric ceramic powder contained in the green sheet and the ceramic powder contained in the conductive paste are powders of the same composition, and for example, barium titanate can be used. In the multilayer ceramic capacitor manufactured using the conductive paste of this embodiment, sheet attack and peeling failure of the green sheet are suppressed even when the thickness of the green sheet is, for example, 3 μm or less.

[0119] Hereinafter, embodiments of electronic components and the like of the present invention will be described with reference to the drawings. The drawings may be represented schematically or at a different scale as appropriate. Furthermore, the positions and directions of components will be described with reference to the XYZ Cartesian coordinate system shown in Figures 1A and 1B as appropriate. In this XYZ Cartesian coordinate system, the X and Y directions are horizontal, and the Z direction is vertical (up and down).

[0120] 1A and 1B are a perspective view and a side cross-sectional view showing a multilayer ceramic capacitor 1, which is an example of an electronic component according to an embodiment. The multilayer ceramic capacitor 1 includes a ceramic laminate 10 in which dielectric layers 12 and internal electrode layers 11 are alternately stacked, and external electrodes 20.

[0121] A method for manufacturing a multilayer ceramic capacitor 1 using the above-described conductive paste will now be described. First, the conductive paste is printed on a dielectric layer made of a green sheet and dried to form a dry film. A plurality of dielectric layers, each having this dry film on its upper surface, are stacked and pressure-bonded to obtain a laminate, which is then fired and integrated to produce a ceramic laminate 10 in which internal electrode layers 11 and dielectric layers 12 are alternately stacked. A pair of external electrodes 20 is then formed on both ends of the ceramic laminate 10 to manufacture the multilayer ceramic capacitor 1. This method will now be described in more detail.

[0122] First, a green sheet is prepared, which is an unfired ceramic sheet made of a dielectric material. Examples of such green sheets include a dielectric layer paste obtained by adding an organic binder such as polyvinyl butyral and a solvent such as terpineol to a predetermined ceramic raw material powder such as barium titanate, and then coating the paste on a support film such as a PET film in a sheet form and drying it to remove the solvent. The thickness of the dielectric layer made of the green sheet is not particularly limited, but is preferably 0.05 μm or more and 3 μm or less in view of the demand for miniaturization of multilayer ceramic capacitors.

[0123] Next, the conductive paste is printed (applied) on one side of this green sheet by a known method such as screen printing, and then dried to form a dry film, to prepare a plurality of sheets. Note that, from the viewpoint of the requirement for thinning of the internal electrode layer 11, the thickness of the conductive paste (dry film) after printing is preferably set to a thickness such that the thickness of the dry film after drying is 1 μm or less.

[0124] Next, the green sheet is peeled off from the support film, and the dielectric layers made of the green sheet and the dry film formed on one side thereof are stacked alternately, and then a laminate is obtained by heat and pressure treatment. Note that a configuration in which protective green sheets not coated with conductive paste are further placed on both sides of the laminate may be adopted.

[0125] Next, the laminate is cut to a predetermined size to form green chips, and the green chips are subjected to a binder removal treatment and fired in a reducing atmosphere to produce the ceramic laminate 10. The binder removal treatment is performed in an atmosphere of air or N ２ It is preferable to carry out the debinding treatment in a gas atmosphere. The temperature during the debinding treatment is, for example, 200°C or higher and 400°C or lower. Furthermore, it is preferable to hold the above temperature for 0.5 hours or higher and 24 hours or lower during the debinding treatment. Furthermore, the firing is carried out in a reducing atmosphere to suppress oxidation of the metal used in the internal electrode layers, and the temperature during firing of the laminate is, for example, 1000°C or higher and 1350°C or lower, and the temperature holding time during firing is, for example, 0.5 hours or higher and 8 hours or lower.

[0126] By firing the green chip, the organic binder in the green sheet is completely removed, and the ceramic raw material powder is fired to form the ceramic dielectric layer 12. Also, the organic vehicle in the dried film is removed, and the nickel powder or the alloy powder mainly composed of nickel is sintered or melted and integrated to form the internal electrode layer 11, thereby forming a fired multilayer ceramic body in which a plurality of dielectric layers 12 and internal electrode layers 11 are alternately stacked. Note that, from the viewpoint of taking oxygen into the dielectric layer to increase reliability and suppressing reoxidation of the internal electrodes, the fired multilayer ceramic body may be subjected to an annealing treatment.

[0127] Then, a pair of external electrodes 20 is provided on the produced fired multilayer ceramic body, thereby producing the multilayer ceramic capacitor 1. For example, the external electrodes 20 include an external electrode layer 21 and a plating layer 22. The external electrode layer 21 is electrically connected to the internal electrode layer 11. Note that, for example, copper, nickel, or an alloy thereof can be suitably used as the material for the external electrodes 20. Note that the electronic component is not limited to a multilayer ceramic capacitor, and may be an electronic component other than a multilayer ceramic capacitor, such as a varistor.

[0128] EXAMPLES The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to these examples.

[0129] The materials used in the examples and comparative examples of the present invention are shown in Table 1.

[0130]

[0131] [Polymer Compound] The polymer compound was synthesized as follows: first, a cellulose compound and a polyvinyl acetal compound were synthesized, and then these were further reacted.

[0132] Synthesis of Cellulose-Based Compounds (Synthesis of Cellulose-Based Compound (1a) Having a Vinyl Group) Ethyl cellulose ("Ethocel STD-10" manufactured by The Dow Chemical Company, number average molecular weight Mn (value calculated as standard polystyrene by GPC): 22,700, average number of unetherified hydroxyl groups among the hydroxyl groups in one cyclic structure of glucose ring: 0.48) was prepared and dried under reduced pressure to evaporate water.

[0133] A solution was obtained by dissolving 100 parts by mass of the dried ethyl cellulose in 900 parts by mass of ethyl acetate. To the obtained solution, 0.50 parts by mass of 3-allyloxypropionic acid, equivalent to an average of one vinyl group introduced per molecule of ethyl cellulose, 0.56 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.011 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at a temperature of 40°C for 5 hours to carry out the reaction. Thereafter, the ethyl acetate was removed to obtain a cellulose-based compound (1a) in which a vinyl group was introduced into ethyl cellulose as a solid.

[0134] A portion of the obtained solid was analyzed by FT-IR and H-NMR, confirming the formation of an ester bond and the introduction of vinyl groups into the ethyl cellulose in the same molar amount as the charged 3-allyloxypropionic acid.

[0135] The cellulose-based compound (1a) obtained as described above contains unreacted ethyl cellulose in addition to the compound in which a vinyl group has been introduced into ethyl cellulose, and this mixture is referred to as cellulose-based compound (1a). The same applies to the ethyl cellulose-based compounds (1c), (1e) to (1i) described below.

[0136] Table 2 shows the number of the synthesized cellulose compound, the type of cellulose used in the synthesis, the weight-average molecular weight, the number-average molecular weight, the type of functional group introduced into the cellulose, the number of functional groups introduced (the average number of functional groups (vinyl groups or thiol groups) introduced per molecule of ethyl cellulose), the average number of hydroxyl groups (the average number of unetherified hydroxyl groups among the hydroxyl groups in one cyclic structure of the glucose ring), the vinyl group (the amount of 3-allyloxypropionic acid used), the thiol group (the amount of 3-mercaptopropionic acid used), the amount of condensing agent used, and the amount of reaction accelerator used. The same is true for the ethyl cellulose compounds (1b) to (1i) mentioned below.

[0137]

[0138] (Synthesis of Cellulose-Based Compounds (1c, 1e to 1i) Having a Vinyl Group) As shown in Table 2, the type and amount of each material used in the synthesis of the cellulose-based compounds were changed from the conditions for synthesizing cellulose-based compound (1a). Otherwise, cellulose-based compounds (1c), (1e) to (1i) having a vinyl group were synthesized under the same conditions as for cellulose-based compound (1a).

[0139] (Synthesis of cellulose compound (1b) having a thiol group) Ethyl cellulose (Dow Chemical's "Ethocel STD-10", number average molecular weight Mn (value obtained by GPC in terms of standard polystyrene): 22,700, average number of unetherified hydroxyl groups among the hydroxyl groups in one cyclic structure of glucose ring: 0.48) was prepared and dried under reduced pressure to evaporate water.

[0140] A solution was obtained by dissolving 100 parts by mass of the dried ethyl cellulose in 900 parts by mass of ethyl acetate. To the obtained solution, 0.48 parts by mass of 3-mercaptopropionic acid, equivalent to an average of one thiol group introduced per molecule of ethyl cellulose, 0.58 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.015 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at a temperature of 40°C for 5 hours to carry out the reaction. Thereafter, the ethyl acetate was removed to obtain a cellulose-based compound (1b) in which a thiol group was introduced into ethyl cellulose as a solid.

[0141] A portion of the obtained solid was analyzed by FT-IR and H-NMR, confirming the formation of an ester bond and the introduction of thiol groups into the ethyl cellulose in the same molar amount as the charged 3-mercaptopropionic acid.

[0142] The cellulose-based compound (1b) obtained by the above-described synthesis method contains unreacted ethyl cellulose in addition to the compound in which a thiol group has been introduced into ethyl cellulose, and this mixture is referred to as cellulose-based compound (1b). The same applies to the ethyl cellulose-based compound (1d) described below.

[0143] (Synthesis of cellulose compound (1d) having a thiol group) The type and amount of each material used in the synthesis of the cellulose compound were changed from those of cellulose compound (1b) as shown in Table 2. Otherwise, synthesis of cellulose compound (1d) having a thiol group was carried out under the same conditions as those for cellulose compound (1b).

[0144] Synthesis of Polyvinyl Acetal Compounds Synthesis of Polyvinyl Butyral Compound (2a) Having Thiol Groups Polyvinyl butyral (BL-S manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn (measured by GPC in terms of standard polystyrene): 23,000, amount of hydroxy groups: approximately 22 mol%) was prepared and dried under reduced pressure to evaporate water.

[0145] 100 parts by mass of dried polyvinyl butyral was dissolved in 900 parts by mass of ethyl acetate. To the resulting solution, 0.48 parts by mass of 3-mercaptopropionic acid, equivalent to an average of one thiol group introduced per molecule of polyvinyl butyral, 0.57 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.014 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at a temperature of 40°C for 5 hours to carry out a reaction. Thereafter, the ethyl acetate was removed to obtain a polyvinyl butyral-based compound (2a) in which a thiol group was introduced into polyvinyl butyral as a solid.

[0146] A portion of the obtained solid was analyzed by FT-IR and H-NMR, and it was confirmed that an ester bond was formed, and that a thiol group in the same molar amount as the charged 3-mercaptopropionic acid was introduced into the polyvinyl butyral.

[0147] The polyvinyl butyral compound (2a) contains unreacted polyvinyl butyral in addition to the compound in which a thiol group has been introduced into polyvinyl butyral, and this mixture is referred to as polyvinyl butyral compound (2a). The same applies to the polyvinyl butyral compounds (2c), (2e) to (2h) described below.

[0148] Table 3 shows the number of the synthesized butyral compound, the type of polyvinyl butyral used in the synthesis, the weight-average molecular weight, the number-average molecular weight, the type of functional group introduced into the polyvinyl butyral, the number of functional groups introduced (the average number of functional groups (vinyl groups or thiol groups) introduced per polyvinyl butyral molecule), the amount of hydroxyl groups, the amount of vinyl groups (amount of 3-allyloxypropionic acid used), the amount of thiol groups (amount of 3-mercaptopropionic acid used), the amount of condensing agent used, and the amount of reaction accelerator used. The same is true for the polyvinyl butyral compounds (2b) to (2h) mentioned below.

[0149]

[0150] (Synthesis of polyvinyl butyral compounds (2c, 2e to 2h) having thiol groups) As shown in Table 2, the type and amount of each material used in the synthesis of the polyvinyl butyral compounds were changed from the conditions used to synthesize the polyvinyl butyral compound (2a). Otherwise, polyvinyl butyral compounds (2c), (2e) to (2h) having thiol groups were synthesized under the same conditions as those used to synthesize the polyvinyl butyral compound (2a).

[0151] (Synthesis of polyvinyl butyral compound (2b) having vinyl groups) Polyvinyl butyral ("BL-S" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn (value calculated as standard polystyrene by GPC): 23,000, amount of hydroxyl groups: approximately 22 mol%) was prepared and dried under reduced pressure to evaporate water.

[0152] A solution was obtained by dissolving 100 parts by mass of the dried polyvinyl butyral in 900 parts by mass of ethyl acetate. To the obtained solution, 0.50 parts by mass of 3-allyloxypropionic acid, which corresponds to an average of one vinyl group introduced per molecule of polyvinyl butyral, 0.55 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.011 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was stirred at a temperature of 40°C for 5 hours to carry out a reaction. The ethyl acetate was then removed to obtain a polyvinyl butyral-based compound (2b) in which a vinyl group was introduced into polyvinyl butyral as a solid.

[0153] A portion of the obtained solid was analyzed by FT-IR and H-NMR, and it was confirmed that an ester bond was formed, and that vinyl groups in the same molar amount as the charged 3-allyloxypropionic acid were introduced into the polyvinyl butyral.

[0154] The polyvinyl butyral compound (2b) obtained by the synthesis method described above contains unreacted polyvinyl butyral in addition to the compound in which a vinyl group has been introduced into polyvinyl butyral, and this mixture including the unreacted polyvinyl butyral will be referred to as polyvinyl butyral compound (2b). The same applies to the polyvinyl butyral compound (2d) described below.

[0155] (Synthesis of polyvinyl butyral compound (2d) having a vinyl group) The type and amount of each material used in the synthesis of the polyvinyl butyral compound were changed from those of polyvinyl butyral compound (2b) as shown in Table 3. Otherwise, polyvinyl butyral compound (2d) having a vinyl group was synthesized under the same conditions as those for polyvinyl butyral compound (2b).

[0156] [Synthesis of Polymer Compound] (Synthesis of Polymer Compound aa) When the total of the cellulose compound, polyvinyl butyral compound, and organic solvent was 100 parts by mass, 7.21 parts by mass of the cellulose compound (1a) and 6.27 parts by mass of the polyvinyl butyral compound (2a) were dissolved in 86.52 parts by mass of dihydroterpineol solvent. This solution was transferred to a glass flask reaction vessel, and after nitrogen substitution, 0.14 parts by mass of azobisisobutyronitrile as a radical initiator was added to the solution. The reaction was carried out at 80 ° C. for 3 hours with stirring to obtain an organic vehicle aa containing the polymer compound aa and dihydroterpineol. Here, the cellulose compound (1a) and the polyvinyl butyral compound (2a) have the same molar number, and as described above, an average of one thiol group was introduced per molecule of polyvinyl butyral, so the molar ratio of sulfur atoms contained in the polymer compound aa to the cellulose compound (1a) was 1. The organic vehicle aa contains about 13.5 parts by mass of polymer compound aa (the total amount of 7.21 parts by mass of cellulose compound (1a) and 6.27 parts by mass of polyvinyl butyral compound (2a)).

[0157] Here, the polymer compound aa is a mixture of a polymer compound in which a cellulose compound (1a) and a polyvinyl butyral compound (2a) are bonded together, unreacted ethyl cellulose, and unreacted polyvinyl butyral, and in the examples, this mixture is referred to as polymer compound aa.

[0158] Furthermore, when the produced polymer compound 1 was analyzed by FT-IR and 1H-NMR, the presence of an -S- bond was confirmed, and it was confirmed that the target structure had been obtained. Furthermore, the weight average molecular weight (Mw: standard polystyrene equivalent value measured by GPC) of polymer compound aa was measured.

[0159] Table 4 shows the number of the organic vehicle containing the synthesized polymer compound, the number and amount (parts by mass) of the cellulose-based compound used in the synthesis (EC-based compound), the number and amount (parts by mass) of the polyvinyl butyral-based compound used in the synthesis (PVB-based compound), the amount (parts by mass) of the organic solvent dihydroterpineol used, the amount (parts by mass) of the radical initiator azobisisobutyronitrile used, and the weight-average molecular weight of the polymer compound obtained by measurement. The polymer compounds bb to ih, cc', and dd' mentioned below are also shown in Table 4.

[0160]

[0161] (Synthesis of polymer compounds bb to ih, cc', and dd') As shown in Table 4, the type and amount of each material used in the synthesis of the polymer compounds were changed from the conditions for synthesizing polymer compound aa. Polymer compounds bb to ih, cc', and dd' were synthesized under the same conditions as for polymer compound aa, and the weight-average molecular weights (Mw: standard polystyrene equivalent value measured by GPC) were measured.

[0162] Example 1 A conductive paste was prepared as follows, and the physical properties of a dried film obtained using the conductive paste were evaluated.

[0163] <Preparation of Conductive Paste> 47 mass % of Ni powder (Ni-1, number average particle size: 0.18 μm) was used as the conductive powder, and BaTiO ３ A conductive paste was prepared by mixing 3.5% by mass of powder (BT-1, number average particle size: 0.05 μm), 3.0% by mass of polymer compound aa, 0.4% by mass of an acrylic polymer dispersant with a carboxyl group (weight average molecular weight: 50,000), and 46.1% by mass of the remaining organic solvent (dihydroterpineol DHT) to a total of 100% by mass, and mixing these materials using a triple roll. The prepared conductive paste was printed and dried as follows, and the surface roughness of the dried film, adhesion to the green sheet, and dry film density were evaluated.

[0164] [Evaluation Method] (Dispersibility: Surface Roughness of Dried Film of Conductive Paste and Adhesion to Green Sheet) <Surface Roughness> The prepared conductive paste was screen-printed onto a 2.54 cm (1 inch) square piece of heat-resistant tempered glass and dried at 120°C in air for 1 hour to prepare a 20 mm square dried film with a film thickness of 1 to 3 μm. If the dispersibility of the conductive paste is good, the surface of the dried film will be smooth. If the dispersibility is poor, aggregation will occur within the conductive paste, causing the surface of the dried film to become rough and reducing surface smoothness. Therefore, the surface roughness Sa (arithmetic mean height) of the prepared dried film was measured using a laser microscope (OLS-5000 manufactured by Evident Co., Ltd.) in accordance with the ISO 25178 standard. The smaller the surface roughness Sa (arithmetic mean height), the smoother the surface of the dried film. The measurement results are shown in Table 5.

[0165] <Adhesion between dried film and green sheet> The prepared conductive paste was applied to a 2.54 cm (1 inch) square BaTiO ３ The conductive paste was printed on the dielectric green sheet so that the film thickness after printing would be 5 to 10 μm. After printing, the green sheet was dried at 120° C. for 20 minutes to form a dry film of the conductive paste on the surface of the green sheet. Next, BaTiO ３ The dielectric green sheet was placed on top, and the dried film of the conductive paste and the BaTiO ３ The dielectric green sheets were thermocompressed to form a laminate. The dried film of the conductive paste and the BaTiO ３ By measuring the force required to peel off the dielectric green sheet, the dry film of the conductive paste and the BaTiO ３ The adhesion to the dielectric green sheet was evaluated by averaging five points measured using a thin film adhesion strength measuring device (Romulus manufactured by QUAD Corporation).

[0166] To explain in detail the process of evaluating adhesion using a thin film adhesion strength measuring instrument, an aluminum stud pin coated with epoxy adhesive is attached vertically to the center of the laminate, and an alumina plate coated with adhesive is attached to the opposite surface, and a sample for adhesion evaluation with the stud pin attached vertically is prepared. The stud pin of the sample is then pulled away from the surface of the laminate, and the dried film of the conductive paste and the BaTiO ３ The adhesion of the dielectric green sheets was evaluated, and the measurement results are shown in Table 5.

[0167] <Dry Film Density> 20 mg of nickel paste was dropped onto glass in a dome shape and dried in a drying oven at 80°C for 2 hours. The dry film density was calculated from the volume determined using a laser microscope (OLS-5000 manufactured by Evident Co., Ltd.) and the difference in weight of the nickel paste before and after drying.

[0168] <Evaluation> Based on the measurement results of the dry film density, surface roughness, and adhesion between the dry film and the green sheet, the performance of the dry film was evaluated as follows: Good: Dry film density is 5.20 g / cm ３ The surface roughness Sa was 55 nm or less, and the adhesion value was 8.0 MPa or more. ×: The dry film density was 5.20 g / cm ３ As mentioned above, there were some samples that did not satisfy either one of the surface roughness Sa of 55 nm or less and the adhesion value of 8.0 MPa or more.

[0169] Even in the case of a thinned dielectric layer (for example, 1.0 μm or less) and an internal electrode layer (for example, 1.5 μm or less) of an MLCC, if the surface roughness Sa is 55 nm or less, a decrease in the insulation resistance of the dielectric layer due to the unevenness of the internal electrode layer can be suppressed, and if the adhesion value is 8.0 MPa or more, poor adhesion can be suppressed even if the dielectric layer and the internal electrode layer are thinned. In addition, the dry film density is 5.20 g / cm ３ If the above conditions are met, the contact area with the dielectric layer can be increased, and the dielectric capacitance of the MLCC can be increased. Therefore, by satisfying the above conditions, the dielectric layer and internal electrode layer can be made thinner, making it possible to manufacture a smaller, larger-capacity MLCC.

[0170] Tables 5 to 7 show the materials used in the conductive paste of Example 1 and the amounts used, the formulation of the conductive paste, the measured values ​​of the dry film density of the dry film formed using the conductive paste, the measured values ​​of the surface roughness Sa, the measured values ​​of the adhesion, and the above evaluation results (◯ or ×). The formulations and measurement results of Examples 2 to 13 and Comparative Examples 1 to 4 are also shown in the same manner as in Example 1.

[0171]

[0172]

[0173]

[0174] [Examples 2 to 13] Based on the formulations shown in Tables 5 and 6, Ni powder, BaTiO ３ Conductive pastes of Examples 2 to 13 were prepared by mixing powders, polymer compounds, dispersants, organic solvents, etc., in the same manner as in Example 1. Dry films were formed using the prepared conductive pastes in the same manner as in Example 1, and the surface roughness, adhesion to the green sheet, and dry film density of the obtained dry films were measured and evaluated in the same manner as in Example 1.

[0175] [Comparative Examples 1 to 4] Based on the formulation shown in Table 7, Ni powder, BaTiO ３ Conductive pastes of Comparative Examples 1 to 4 were prepared by mixing powders, polymer compounds, dispersants, organic solvents, etc., in the same manner as in Example 1. Dry films were formed using the prepared conductive pastes in the same manner as in Example 1, and the surface roughness, adhesion to the green sheet, and dry film density of the obtained dry films were measured and evaluated in the same manner as in Example 1.

[0176] [Evaluation Results] As shown in Tables 5 and 6, the dry films formed using the conductive pastes of Examples 1 to 13 had a dry film density of 5.20 g / cm ３As described above, it can be seen that the surface roughness Sa (arithmetic mean height) is 55 nm or less and the adhesion is 8.0 MPa or more. In contrast, the dried film formed with the conductive paste of Comparative Example 1 exhibited poor adhesion because the present invention does not contain a polymer compound. The dried film formed with the conductive paste of Comparative Example 2 exhibited poor surface roughness because the molecular weight of the polymer compound was 150,000 or more. The dried film formed with the conductive paste of Comparative Example 3 exhibited poor adhesion because the molecular weight of the polymer compound was less than 30,000. The dried film formed with the conductive paste of Comparative Example 4 exhibited poor surface roughness because the molar ratio of sulfur atoms to the cellulose-based compound exceeded 1.7.

[0177] As described above, the conductive paste of the present invention can provide a conductive paste having a smooth dry film and excellent adhesion even when using finely divided conductive powders or ceramic powders. Therefore, it can be suitably used as a raw material for internal electrodes of multilayer ceramic capacitors, which are chip components (electronic components) in electronic devices such as mobile phones and digital devices, and is therefore industrially useful.

[0178] REFERENCE SIGNS LIST 1 Multilayer ceramic capacitor 10 Ceramic laminate 11 Internal electrode layer 12 Dielectric layer 20 External electrode 21 External electrode layer 22 Plated layer

Claims

1. A conductive paste comprising a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent, wherein the binder resin contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by a sulfur atom, the molar ratio of the sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the weight average molecular weight of the polymer compound is 30,000 or more and less than 150,000.

2. The conductive paste according to claim 1, wherein the weight average molecular weight of the polymer compound is 60,000 or more and 130,000 or less.

3. The cellulose-based compound is a cellulose derivative having a thiol group or a vinyl group, the polyvinyl acetal-based compound is a polyvinyl acetal resin having a thiol group or a vinyl group, and when the cellulose derivative has a thiol group, the polyvinyl acetal resin has a vinyl group that reacts with the thiol group, and when the cellulose derivative has a vinyl group, the polyvinyl acetal resin has a thiol group that reacts with the vinyl group. The conductive paste according to claim 1.

4. The conductive paste according to claim 3, wherein the cellulose derivative is ethyl cellulose having a thiol group or a vinyl group, and the polyvinyl acetal resin is polyvinyl butyral having a thiol group or a vinyl group.

5. The cellulose-based compound is a first esterification reactant obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group and a hydroxyl group of cellulose, and the polyvinyl acetal-based compound is a second esterification reactant obtained by dehydration condensation of a carboxy group of a carboxylic acid having a thiol group or a vinyl group and a hydroxyl group of polyvinyl acetal. When the first esterification reactant has a thiol group, the second esterification reactant has a vinyl group, and when the first esterification reactant has a vinyl group, the second esterification reactant has a thiol group. The conductive paste according to claim 1, wherein the polymer compound is a thiol-ene reactant of the first esterification reactant and the second esterification reactant.

6. The first esterification reactant is an esterification reactant obtained by dehydration condensation of the carboxy group of 3 - allyloxypropionic acid and the hydroxyl group of ethyl cellulose, and the second esterification reactant is an esterification reactant obtained by dehydration condensation of the carboxy group of 3 - mercaptopropionic acid and the hydroxyl group of polyvinyl butyral. The conductive paste according to claim 5.

7. The binder resin contains at least one of cellulose and polyvinyl acetal. The conductive paste according to claim 1.

8. The conductive powder is nickel powder. The conductive paste according to claim 1.

9. The number average particle diameter of the conductive powder is 0.05 μm or more and 0.3 μm or less. The conductive paste according to claim 1.

10. The ceramic powder contains barium titanate. The conductive paste according to claim 1.

11. The number average particle diameter of the ceramic powder is 0.01 μm or more and 0.5 μm or less. The conductive paste according to claim 1.

12. The content of the ceramic powder is 1% by mass or more and 20% by mass or less. The conductive paste according to claim 1.

13. For use as an internal electrode of a multilayer ceramic component. The conductive paste according to claim 1.

14. An electronic component formed using the conductive paste according to claim 1.

15. Having at least a laminate in which a dielectric layer and an internal electrode layer are laminated, and the internal electrode layer is formed using the conductive paste according to claim 1. A multilayer ceramic capacitor.

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