Vehicle, conductive paste, electronic component, and multilayer ceramic capacitor

Abstract

To provide a vehicle and a conductive paste with which it is possible to suppress sheet attack of a green sheet while maintaining good smoothness and dry film density of a conductive paste that uses a fine conductive powder and a ceramic powder for miniaturization and thinning of a multilayer ceramic electronic component, and to provide an electronic component and a multilayer ceramic capacitor.　Provided is a vehicle containing a binder resin and an organic solvent, wherein the binder resin contains a polymer compound in which a cellulose compound and a polyvinyl acetal compound are bonded by a sulfur atom, the molar ratio of sulfur atoms contained in the polymer compound to the cellulose compound is 0.3-1.7, and the hydrogen bonding term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa0.5 or less.

Description

Vehicle, conductive paste, electronic component, and multilayer ceramic capacitor

[0001] The present invention relates to a vehicle, 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) and a binder resin such as polyvinyl acetal resin (PVA), and then dried to form a dry film. The dry film and green sheet are then alternately stacked and heat-pressed to form a laminate in which the dry film and green sheet are integrated. 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 the chip is fired to form external electrodes. The surfaces of the external electrodes are then nickel-plated or otherwise processed 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, thinner electrode films with excellent density and continuity for internal electrodes using nickel or the like, and ceramic dielectric materials and dielectric layers using such materials are being studied to have higher dielectric constants and thinner layers, with dielectric layers with thicknesses of 1.0 μm or less already in practical use. It is also desirable to reduce the thickness of the electrode films to 1.0 μm or less.

[0005] As MLCCs become thinner, the adhesion between the green sheets and the internal electrode layers decreases, resulting in frequent peeling and misalignment during lamination due to poor adhesion. This poor adhesion can lead to short circuits in multilayer ceramic capacitors, for example. In particular, the need 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 adhesion. Weak adhesion between sheets can cause structural defects such as voids, delamination, and cracks during firing, reducing the yield of MLCCs. In other words, the purpose of improving the adhesion between the internal electrode layers and the green sheets is to prevent cracking.

[0006] The use of polyvinyl acetal resin as the organic binder in the conductive paste can prevent the electrodes from peeling off when the laminate is cut. It is also desirable to add cellulose resin to the conductive paste to impart the desired rheological properties.

[0007] Therefore, Patent Document 1 discloses that the internal electrode paste can contain an organic resin, and that the organic binder resin is preferably a mixed system of ethyl cellulose (EC) and polyvinyl butyral (PVB) resin, which is a type of polyvinyl acetal (PVA) resin.

[0008] However, if the conductive paste for the internal electrodes contains PVA, the solvent used in the conductive paste must dissolve PVA. In this case, depending on the solvent that dissolves the PVA contained in the conductive paste, the PVA contained in the green sheet may be dissolved and eroded, resulting in sheet attack. Sheet attack can cause localized thinning of the green sheet or holes 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. Therefore, Patent Document 2 discloses a special solvent composition that can address sheet attack.

[0009] JP 2009-147359 JP 2020-057691

[0010] Generally, when two organic binder resins with significantly different structures are mixed, the resulting combination is almost always incompatible (immiscible). In the case of an immiscible system, the two organic binder resins are essentially not soluble in each other and exist independently, so not only are the expected performance not achieved by using the two organic binder resins not achieved, but the functionality is often significantly reduced compared to when each organic binder is used alone. Furthermore, since the mixture contains a solvent suitable for the two organic binder resins, the solvent that dissolves the PVA is more likely to cause the sheet attack described above.

[0011] If organic binder resins that are normally immiscible can be made to dissolve in each other, it will be possible to combine the advantages of both, stabilize the interface between the different polymers, and achieve a uniform and stable dispersion state.

[0012] The conductive paste disclosed in Patent Document 1 contains polyvinyl butyral resin, which can improve the adhesion between the dried film and the green sheet. However, this technology uses a combination of ethyl cellulose resin and polyvinyl butyral resin, which results in poor compatibility between the two resins, which can lead to insufficient dispersion of the conductive powder and ceramic powder in the conductive paste, and insufficient density and smoothness of the dried film of the conductive paste.

[0013] Furthermore, when a conductive paste contains a polyvinyl acetal resin and a cellulose-based resin, it is important to select a solvent that can dissolve both resins or a mixture of multiple solvents as the solvent used for the conductive paste. At the same time, it is also necessary to select a solvent that can suppress sheet attack. In particular, if a solvent that can dissolve polyvinyl acetal resin is selected as the solvent for the conductive paste, sheet attack may occur if the solubility of the solvent in the polyvinyl acetal resin contained in the green sheet is not taken into consideration.

[0014] In view of these circumstances, the present invention aims to provide a vehicle, a conductive paste, an electronic component, and a multilayer ceramic capacitor that can suppress sheet attack on a green sheet while maintaining good smoothness and density of the dried film of the conductive paste in a conductive paste that uses a finely divided conductive powder or ceramic powder for the purpose of making multilayer ceramic electronic components smaller and thinner.

[0015] In order to solve the above problems, the vehicle of the present invention is a vehicle containing 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 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 hydrogen bond term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa. ０．５ The following is the result.

[0016] The hydrogen bond parameter δh of the Hansen solubility parameter of the polymer compound is 6.5 to 8.5 MPa. ０．５ may be.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] In order to solve the above problems, the conductive paste of the present invention is a conductive paste containing the vehicle of the present invention, a conductive powder, and a ceramic powder, wherein the hydrogen bond term δh of the Hansen solubility parameter of the organic solvent in the conductive paste is 6.5 MPa. ０．５ The following is the result.

[0022] The number average particle size of the conductive powder may be 0.05 μm or more and 1.0 μm or less.

[0023] The ceramic powder may include barium titanate.

[0024] The ceramic powder may have a number average particle size of 0.01 μm or more and 0.5 μm or less.

[0025] The content of the ceramic powder may be 1% by mass or more and 20% by mass or less.

[0026] The conductive paste of the present invention may be used for internal electrodes of multilayer ceramic components.

[0027] 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.

[0028] 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.

[0029] The vehicle of the present invention can exhibit the characteristics of polyvinyl acetal resin by selecting the binder resin, while suppressing sheet attack of the conductive paste by selecting the solvent. Furthermore, the conductive paste using the vehicle of the present invention has excellent dispersibility of the conductive powder and a high surface smoothness in the dried film 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 a small surface roughness and a high dried film density.

[0030] 1A and 1B are perspective and cross-sectional views of the multilayer ceramic capacitor according to the present embodiment.

[0031] Hereinafter, an embodiment of the vehicle, conductive paste, electronic component, and multilayer ceramic capacitor of the present invention will be described.

[0032] [Vehicle] The vehicle of the present invention contains a binder resin and an organic solvent, which will be described below.

[0033] <Binder Resin> The binder resin contained in the vehicle contains a polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded by sulfur atoms, and the molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, i.e., in the polymer compound, the ratio of cellulose-based compound:sulfur atoms is 1.0:0.3 to 1.7.

[0034] The mass average molecular weight (Mw) of the polymer compound is preferably 20,000 to 200,000, as calculated by gel permeation chromatography (GPC) using standard polystyrene. If the number average molecular weight of the polymer compound is less than 20,000, the viscosity of the conductive paste prepared using the polymer compound will be extremely low, making it difficult to adjust the viscosity to an appropriate level for the conductive paste. Furthermore, if the mass average molecular weight of the polymer compound exceeds 200,000, the viscosity of the conductive paste prepared using the polymer compound will be extremely high, making it difficult to adjust the viscosity to an appropriate level for the conductive paste. In order to adjust the viscosity to an appropriate level, it may be necessary to reduce the content of the conductive powder or ceramic powder below the appropriate amount.

[0035] The polymer compound molecules of this embodiment contain both cellulose-based and polyvinyl acetal-based compounds, allowing the dried film obtained from the conductive paste of this embodiment to have the surface smoothness provided by the cellulose-based compound and the adhesion to the green sheet provided by the polyvinyl acetal-based compound. Furthermore, the polymer compound contains the structures of the cellulose-based compound and the polyvinyl acetal-based compound, which are incompatible with each other, within the same molecule, thereby eliminating poor dispersion of the conductive paste.

[0036] Here, if the molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.5 to 2, the surface roughness of the dried film is superior to that of conventional conductive pastes that use cellulose and polyvinyl acetal resin in combination as binder resins. Furthermore, if the molar ratio is 0.3 to 1.7, the surface roughness and dry film density of the dried film of the conductive paste are even superior. The molar ratio of sulfur atoms contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and more preferably 0.5 to 1.5.

[0037] (Hydrogen Bond Term δh of Hansen Solubility Parameters for Polymer Compounds) The Hansen Solubility Parameter is known as a measure of the solubility of a resin in a solvent. The Hansen Solubility Parameter (HSP) is based on the idea that two substances with similar intermolecular interactions are more likely to dissolve in each other. The concept of the Hansen Solubility Parameter also applies to the relationship between a resin and a solvent. The Hansen Solubility Parameter has three terms: a dispersion term (δd), a polar term (δp), and a hydrogen bond term (δh). In the vehicle and conductive paste of this embodiment, the hydrogen bond term (δh) affects the dissolution of cellulose, polyvinyl acetal resin, and the polymer compound in an organic solvent.

[0038] Hansen solubility parameter values ​​may vary depending on the source, but in this embodiment, for solvents registered in the database of the Hansen solubility parameter software HSPiP (Hansen Solubility Parameter in Practice) version 5, the registered values ​​were used. For solvents not registered, estimated values ​​calculated by HSPiP version 5 were used. For resins registered in the database, the registered values ​​were used. For resins not registered in the database, tests were conducted to dissolve the resin in 20 solvents with known HSP values, and the Hansen sphere was searched and calculated using HSPiP version 5 from the HSP values ​​of soluble solvents.

[0039] The δh of the HSP of the cellulose-based resin ethyl cellulose is 5.5 to 6.5 MPa. ０．５ The δh of the HSP of the polyvinyl butyral resin of the polyvinyl acetal resin is 10 to 11 MPa. ０．５ The polymer compound contained in the vehicle and conductive paste of this embodiment has a structure derived from polyvinyl acetal resin in its molecule, but the δh of its HSP is 6.5 to 8.5 MPa. ０．５ This is a value close to that of ethyl cellulose.

[0040] Here, the value of each term of the HSP of each resin or polymer compound is the value corresponding to the center of the Hansen sphere. This means that the polymer compound of this embodiment can be used with a solvent suitable for dissolving ethyl cellulose. Therefore, the amount of solvent used that is likely to cause sheet attack and is suitable for dissolving the polyvinyl acetal resin contained in the green sheet can be reduced. The solubility of the polymer compound of this embodiment in solvents makes it possible to suppress sheet attack. The polymer compound of this embodiment has a cellulose structure within its molecule, so it dissolves in a solvent suitable for cellulose.

[0041] (Polymer Compound) The polymer compound in which a cellulose-based compound and a polyvinyl acetal-based compound are bonded, which can be used in this embodiment, will be described in more detail.

[0042] Both cellulose and polyvinyl acetal have hydroxyl groups in their molecules. Functional groups capable of reacting with other compounds to form bonds are introduced into the hydroxyl groups of cellulose, resulting in a cellulose-based compound chemically modified with the reactive functional group. Meanwhile, functional groups capable of reacting with other compounds to form bonds and different from the functional groups introduced into the cellulose-based compound are introduced into the hydroxyl groups of polyvinyl acetal-based polymer compounds, resulting in a polyvinyl acetal-based compound chemically modified with the reactive functional group. In other words, the reactive functional groups introduced into the cellulose-based compound and the reactive functional groups introduced into the polyvinyl acetal-based compound are different. While the functional groups introduced into the cellulose-based compound and the functional groups introduced into the polyvinyl acetal-based compound react, the same functional groups do not react easily. Here, the reason why the same functional groups do not react easily is to prevent bonding between cellulose-based compounds and between polyvinyl acetal-based compounds.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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 type of cellulose may be used, or two or more types may be used in combination.

[0047] Since the conductive paste of the 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.

[0048] The molecular weight of the cellulose affects the viscosity of the conductive paste of this embodiment. The number average molecular weight (Mn) of the cellulose, as calculated using standard polystyrene standards by GPC, is preferably 10,000 to 100,000, and more preferably 10,000 to 80,000.

[0049] If the number average molecular weight of cellulose is less than 10,000, the viscosity of the conductive paste produced using it may be lower than the appropriate viscosity, and if the number average molecular weight of cellulose exceeds 100,000, the viscosity of the conductive paste produced using it may be too high.

[0050] Not all of the hydroxyl groups in cellulose are chemically modified. Before chemical modification, the glucose rings that make up the cellulose have three hydroxyl groups per ring structure. However, after chemical modification, on average, 0.1 to 1 hydroxyl group per ring structure of the glucose rings that make up the cellulose remains as hydroxyl groups and is not chemically modified. In the present invention, reactive functional groups are introduced into these unmodified hydroxyl groups.

[0051] 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).

[0052] 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.

[0053] 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.

[0054] The molecular weight of polyvinyl acetal used as a polymer compound affects the film strength and the viscosity of the solution. Therefore, the number average molecular weight of polyvinyl acetal is preferably in the range of 5,000 to 150,000, and more preferably in the range of 10,000 to 100,000, as calculated using standard polystyrene standards by GPC.

[0055] If the number-average molecular weight of the polyvinyl acetal is less than 5,000, the viscosity of the conductive paste produced using it may be lower than the appropriate viscosity. On the other hand, if the number-average molecular weight of the polyvinyl acetal is more than 150,000, the viscosity of the conductive paste produced using it may be too high.

[0056] 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.

[0057] 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.

[0058] (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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 carboxy group that forms an ester bond with a hydroxyl group and a vinyl group or 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 %.

[0063] The polymer compound used in this embodiment has a molar ratio of sulfur atoms to the cellulose compound of 0.3 to 1.7 (cellulose compound:sulfur atoms=1.0:0.3 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.

[0064] 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 without any functional groups reactive with other compounds, a cellulose-based compound with one functional group reactive with other compounds, and a cellulose-based compound with multiple functional groups reactive with other compounds 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 with multiple functional groups, and cellulose with one functional group is referred to as the cellulose-based compound. After the synthesis of the cellulose-based compound is completed, the solvent can be removed by distillation.

[0065] 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 %.

[0066] 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.

[0067] The polymer compound used in this embodiment is synthesized by dissolving a cellulose-based compound and a polyvinyl acetal-based compound in a solvent, adding a radical generator, 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 the cellulose-based compound and the polyvinyl acetal-based compound bonding together.

[0068] Alternatively, the cellulose compound and the polyvinyl acetal compound may be dissolved in a solvent, and a nucleophilic agent such as a base such as an amine may be added thereto, followed by heating.

[0069] The temperature for the reaction to bond the cellulose compound and the polyvinyl acetal compound can be appropriately selected, but is preferably 60° C. or higher.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] The reaction of bonding a cellulose compound with a polyvinyl acetal compound is preferably carried out in a solvent for the vehicle of this embodiment, which will be described later. When the reaction of bonding a cellulose compound with a polyvinyl acetal compound is carried out in a solvent for the vehicle, the polymer compound of this embodiment is obtained in a state dissolved in the solvent for the vehicle. In other words, by carrying out the reaction of bonding a cellulose compound with a polyvinyl acetal compound, a vehicle in which the polymer compound is dissolved in the solvent can be obtained.

[0074] Furthermore, the vehicle of this embodiment may contain a cellulose resin and a polyvinyl acetal resin in addition to the polymer compound, or may contain either or both of the cellulose resin and the polyvinyl acetal resin separately from the polymer compound.

[0075] Generally, cellulose resin and polyvinyl acetal resin are not compatible with each other, as described above. However, the polymer compound can help the cellulose resin and polyvinyl acetal resin become compatible with each other and suppress phase separation between the cellulose resin and polyvinyl acetal resin. Furthermore, because the polymer compound can help the cellulose resin and polyvinyl acetal resin become compatible with each other, even if a solvent that dissolves cellulose resin more easily than polyvinyl acetal resin is used as a vehicle or conductive paste, the polymer compound coexists with the polyvinyl acetal resin, thereby dissolving the polyvinyl acetal resin. These effects are due to the polymer compound having a cellulose compound skeleton and a polyacetal compound skeleton in its molecule.

[0076] In the vehicle of this embodiment, the proportion of the polymer compound relative to the total mass of the cellulose resin, polyvinyl acetal 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 resin, polyvinyl acetal 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 resin, polyvinyl acetal resin, and polymer compound in the binder resin may be 99% by mass or less, or 95% by mass or less.

[0077] When such phase separation occurs, the binder resin, conductive powder, and ceramic powder are unevenly distributed in the dried film obtained by printing (applying) and drying the conductive paste, and voids where no conductive material is present may occur in the internal electrode obtained by firing the dried film due to the uneven distribution of the binder resin and ceramic powder. When voids occur in such internal electrodes, the area of ​​the internal electrode becomes smaller, 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 uniform particle distribution in the dried film. As a result, the film breakage phenomenon of the electrode layer after firing is resolved, and the capacity of the MLCC is increased.

[0078] The vehicle of this embodiment can contain one or more resins selected from cellulose resin and polyvinyl acetal resin, which improves the flexibility in adjusting the viscosity of the conductive paste. That is, since the cellulose resin and polyvinyl acetal resin can be appropriately added within the range of this embodiment, it becomes easy to adjust the viscosity of the conductive paste.

[0079] Usable cellulose resins include methyl cellulose resin, ethyl cellulose resin, ethyl hydroxyethyl cellulose resin, and nitrocellulose resin, with ethyl cellulose resin being preferred. These cellulose resins can be used alone or in combination. Polyvinyl acetal resins include polyvinyl butyral. Either the cellulose resin or the polyvinyl acetal resin can be used alone, or both can be used. The blending ratio of the cellulose resin, the polyvinyl acetal resin, and the polymer compound can be appropriately selected as long as it does not deviate from the scope of this embodiment. By selecting these resins and their blending ratios, the viscosity of the conductive paste and the adhesion of the resulting dried film to the green sheet can be appropriately adjusted.

[0080] In this embodiment, in addition to the cellulose resin and polyvinyl acetal resin, it is also possible to add known binder resins such as acrylic resins and maleic acid ester resins. The number average molecular weight of the resins that can be added in this way, other than the cellulose resin and polyvinyl acetal resin, is about 20,000 to 300,000 as determined by GPC (gel permeation chromatography) analysis.

[0081] <Organic Solvent> The solvent that can be used for the vehicle of this embodiment is a solvent having an HSP δh of 6.5 MPa. ０．５ is preferably 6 MPa or less ０．５ or less, and more preferably 5.5 MPa ０．５ More preferably, it is 5 MPa or less. ０．５ On the other hand, the lower limit of δh of the HSP of the solvent is 0.5 MPa. ０．５ or more, preferably 1.5 MPa ０．５More preferably, 2.5 MPa ０．５ The solvent may be one type or a mixed solvent of multiple types. The Hansen solubility parameter of a mixed solvent can be calculated by multiplying the volume fraction of the solvents constituting the mixed solvent by the δd, δp, and δh of the HSP of the solvent and adding up the results. Of course, the solvent used in the vehicle of this embodiment has an HSP δh of 6.5 MPa. ０．５ If the lower limit of δh of HSP is 0.5 MPa, it is suitable for dissolving polymer compounds and cellulose-based resins, but is not suitable for dissolving the butyral resin contained in the green sheet. In this embodiment, the sheet attack is suppressed by taking into consideration the solubility of the butyral resin in the solvent that can be used in the vehicle. ０．５ If the temperature is above this level, it is possible to dissolve the polymer compound and the cellulose-based resin.

[0082] Examples of such solvents that can be used as a single solvent include acetate solvents such as isobornyl acetate, isobornyl propionate, isobornyl butyrate, and isobornyl isobutyrate; diethylene glycol monoethyl ether acetate; ether solvents such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and ethylene glycol dibutyl ether; and terpene solvents such as dihydroterpinyl acetate and terpinyl acetate.

[0083] In addition, in the case of a mixed solvent composed of multiple solvents, the value of δh of HSP is 6.5 MPa. ０．５ Ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monobutyl ether acetate, terpineol, and dihydroterpineol may be added provided that the following conditions are met.

[0084] The solvent contained in the vehicle of this embodiment has an HSP δh of 6.5 MPa. ０．５ is preferably 6 MPa or less ０．５ or less, and more preferably 5.5 MPa ０．５Further examples include hydrocarbon solvents such as tridecane, nonane, and cyclohexane, and petroleum hydrocarbon solvents such as mineral spirits. One type of organic solvent may be used, or a mixed solvent of two or more types may be used.

[0085] (Contents of binder resin and organic solvent in the vehicle) The vehicle is one of the raw materials of the conductive paste described below, and may be a mixture of a polymer compound and an organic solvent obtained by reacting a cellulose compound and a polyvinyl acetal compound in an organic solvent. Furthermore, the vehicle may be a mixture to which an organic solvent has been further added. Furthermore, the vehicle may be a vehicle obtained by dissolving a solid polymer compound in an organic solvent.

[0086] Therefore, the content of the binder resin and the content of the organic solvent in the vehicle can be adjusted as appropriate. For example, the mass ratio of the binder resin to the organic solvent may be adjusted so that the entire amount of the binder resin and the organic solvent in the conductive paste to be produced are contained in the vehicle, or the mass ratio of the binder resin to the organic solvent may be adjusted so that the entire amount of the binder resin and a portion of the organic solvent in the conductive paste are contained in the vehicle. For example, the mass ratio of the binder to the organic solvent in the vehicle may be 5 to 50:95 to 50.

[0087] [Conductive Paste] The conductive paste of this embodiment contains a vehicle, a conductive powder, and a ceramic powder. Each component will be described in detail below.

[0088] <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.

[0089] 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.

[0090] The number average particle diameter 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, 0.05 μm or more and 1.0 μm or less. For example, for multilayer ceramic capacitors, which are becoming thinner, the number average particle diameter of the conductive powder is preferably 0.5 μm or less, more preferably 0.3 μm or less. If the number average particle diameter exceeds 0.5 μm, the internal electrode surface becomes significantly uneven, which may degrade the electrical characteristics of the capacitor, which is undesirable. Furthermore, the lower limit of the number average particle diameter of the conductive powder is not particularly limited, but is, for example, 0.03 μm or more. If the number average particle diameter is less than 0.03 μm, handling may become extremely difficult.

[0091] 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.

[0092] 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.

[0093] <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 )

[0094] 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.

[0095] 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.

[0096] 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 a conductive paste for internal electrodes, it is possible to form sufficiently thin, uniform internal electrodes. 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.

[0097] 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.

[0098] 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 conductive powder is 1% by mass or more and 20% by mass or less, the conductive paste has excellent conductivity and dispersibility.

[0099] The vehicle is specifically described in the section on [Vehicle], and therefore a detailed description thereof will be omitted here. The vehicle can be included in the conductive paste so that 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, and more preferably 1 part by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the conductive powder.

[0100] 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, excellent conductivity and dispersibility are achieved. Therefore, the vehicle can be included in the conductive paste so that the content of the binder resin is 0.5% by mass or more and 10% by mass or less.

[0101] In the conductive paste of this embodiment, the proportion of the polymer compound relative to the total mass of the cellulose resin, polyvinyl acetal 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 resin, polyvinyl acetal 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 resin, polyvinyl acetal resin, and polymer compound in the binder resin may be 99% by mass or less, or 95% by mass.

[0102] <Binder Resin> The conductive paste of this embodiment may further contain a binder resin in addition to the binder resin contained in the vehicle. Examples of binder resins that can be contained include the same resins as the binder resins that can be contained in the vehicle, such as the polymer compounds, cellulose resins, polyvinyl acetal resins, acrylic resins, maleic acid ester resins, etc. Details of these binder resins have already been described, so they will not be described here.

[0103] As already explained, the content of the polymer compound is preferably 1 part by mass to 10 parts by mass, and more preferably 1 part by mass to 8 parts by mass, relative to 100 parts by mass of the conductive powder, and the content of the binder resin is preferably 0.5% by mass to 10% by mass, and more preferably 1% by mass to 6% by mass, relative to the total amount of the conductive paste. Even when the conductive paste further contains a binder resin in addition to the vehicle, the total content of the binder resin in the conductive paste is preferably within these ranges.

[0104] <Organic Solvent> The conductive paste of this embodiment may further contain an organic solvent in addition to the organic solvent contained in the vehicle. Examples of organic solvents that can be contained include the same organic solvents that can be contained in the vehicle. Examples of solvents that can be used alone include acetate-based solvents such as isobornyl acetate, isobornyl propionate, isobornyl butyrate, and isobornyl isobutyrate in the conductive paste, diethylene glycol monobutyl ether acetate, and other similar solvents; ether-based solvents such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and ethylene glycol dibutyl ether; terpene-based solvents such as dihydroterpinyl acetate and terpinyl acetate; hydrocarbon-based solvents such as tridecane, nonane, and cyclohexane; and petroleum-based hydrocarbon solvents such as mineral spirits. The organic solvent may be used alone or in a mixed solvent of two or more different solvents.

[0105] The solvent contained in the conductive paste of this embodiment has an HSP δh of 6.5 MPa. ０．５ is preferably 6 MPa or less ０．５ or less, and more preferably 5.5 MPa ０．５ In addition, in the case of a mixed solvent composed of a plurality of solvents, the value of δh of HSP is 6.5 MPa or less. ０．５ Ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol monobutyl ether acetate, terpineol, and dihydroterpineol may be added provided that the following conditions are met.

[0106] 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, excellent conductivity and dispersibility are achieved. Note that this range of the organic solvent content is the same not only when only the organic solvent contained in the vehicle is used in the conductive paste, but also when an organic solvent is further contained in the conductive paste in addition to the organic solvent contained in the vehicle.

[0107] 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, excellent conductivity and dispersibility are obtained. Note that this range of the organic solvent content is the same not only when only the organic solvent contained in the vehicle is used in the conductive paste, but also when an organic solvent is further contained in the conductive paste in addition to the organic solvent contained in the vehicle.

[0108] <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 the wettability of the organic vehicle to the inorganic powder, thereby dispersing the inorganic powder in the conductive paste. The dispersant (surfactant, etc.) may include an acid dispersant including a higher fatty acid, a polymer surfactant, etc., a cationic dispersant other than an acid dispersant, a nonionic dispersant, an amphoteric surfactant, a polymer dispersant, etc.

[0109] 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.

[0110] 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.

[0111] 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, problems such as poor drying properties and a decrease in dry film density may occur.

[0112] 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.

[0113] Anionic polymer dispersants preferably have graft chains, which are expected to improve solubility in various organic solvents.

[0114] 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.

[0115] Such polymer dispersants have carboxyl groups or carboxylic anhydride groups as functional groups in the main chain, and anionic polymer dispersants preferably further have oxyethylene groups in the graft chains from the viewpoint of adsorption to inorganic powders.

[0116] 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.

[0117] Furthermore, the conductive paste of this embodiment may contain a dispersant other than the anionic polymer dispersant. For example, the dispersant (surfactant, etc.) 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.

[0118] 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.

[0119] 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 an 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 become too viscous.

[0120] 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, problems such as poor drying properties and a decrease in dry film density may occur.

[0121] (Other Additives) Furthermore, additives such as known plasticizers can be added to the conductive paste in order to impart flexibility to the dried film obtained from the conductive paste.

[0122] (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.

[0123] 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.

[0124] The surface smoothness of a dried 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 (using a Keyence VK-X120 to measure the arithmetic mean height Sa according to ISO 25178). When the surface smoothness of the dried film is evaluated by the arithmetic mean height Sa, the value is preferably 0.10 μm or less. A surface roughness of 0.10 μm or less using the method described in the Examples can achieve low surface roughness even after printing and drying on a green sheet. Considering the manufacturing process of a multilayer ceramic capacitor, if the surface roughness of the dried conductive paste film is low, the dried conductive paste film will adhere to the green sheet as a surface, resulting in excellent adhesion between the dried conductive paste film and the green sheet. Therefore, it is desirable for the surface roughness of the dried conductive paste film to be as low as possible.

[0125] [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.

[0126] 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.

[0127] 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).

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] [Preparation of Vehicle] As described below, a cellulose compound and a polyvinyl acetal compound were synthesized, and then these were bonded to synthesize a polymer compound, thereby preparing a vehicle.

[0138] (Synthesis of Cellulose-Based Compound (1a) Having a Vinyl Group) Ethyl cellulose ("Ethocel STD-100" manufactured by Dow Chemical, number average molecular weight Mn (value calculated as standard polystyrene by GPC): 63,420, average number of unetherified hydroxyl groups among the hydroxyl groups in one cyclic structure of glucose ring: 0.48) was prepared and dried. Here, the ethyl cellulose was dried to remove moisture adsorbed by the ethyl cellulose. Drying was carried out under reduced pressure at room temperature.

[0139] 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, 0.17 parts by mass of 3-allyloxypropionic acid, which corresponds to an average of one vinyl group introduced per molecule of ethyl cellulose, 0.20 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.004 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.

[0140] 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.

[0141] In addition to the compound in which a vinyl group has been introduced into ethyl cellulose, the cellulose-based compound (1a) also contains unreacted ethyl cellulose, and in the examples, this mixture is referred to as the cellulose-based compound (1a). The same applies to the cellulose-based compound (2a) described below.

[0142] (Synthesis of Polyvinyl Butyral Compound (1b) Having Thiol Groups) Polyvinyl butyral ("BM-SZ" manufactured by Sekisui Chemical Co., Ltd., number average molecular weight Mn (measured by GPC in terms of standard polystyrene): 55,000, amount of hydroxyl groups: approximately 22 mol%) was prepared and dried. The polyvinyl butyral was dried in order to remove moisture adsorbed by the polyvinyl butyral. Drying was carried out under reduced pressure at room temperature. 100 parts by mass of the dried polyvinyl butyral was dissolved in 900 parts by mass of ethyl acetate. To the resulting solution, 0.20 parts by mass of 3-mercaptopropionic acid, equivalent to an average of one thiol group introduced per molecule of polyvinyl butyral, 0.24 parts by mass of diisopropylcarbodiimide as a condensing agent, and 0.005 parts by mass of dimethylaminopyridine as a reaction accelerator were added, and the mixture was reacted at 40°C for 5 hours with stirring. Thereafter, the ethyl acetate was removed to obtain a polyvinyl butyral compound (1b) in which a thiol group was introduced into polyvinyl butyral as a solid.

[0143] 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 polyvinyl butyral in the same molar amount as the charged 3-mercaptopropionic acid.

[0144] In addition to the compound in which a thiol group is introduced into polyvinyl butyral, the polyvinyl butyral-based compound (1b) also contains unreacted polyvinyl butyral, and in the examples, this mixture is referred to as polyvinyl butyral-based compound (1b). The same applies to the polyvinyl butyral-based compound (2b) described below.

[0145] (Synthesis of Cellulose-Based Compound (2a) Having a Vinyl Group) Cellulose-based compound (2a) was synthesized in the same manner as for cellulose-based compound (1a), except that 3-allyloxypropionic acid was added in an amount equivalent to an average of two units per molecule of ethyl cellulose.

[0146] (Synthesis of polyvinyl butyral-based compound (2b) having a thiol group) A polyvinyl butyral-based compound (2b) was synthesized in the same manner as for polyvinyl butyral-based compound (1b), except that 3-mercaptopropionic acid was added in an amount corresponding to an average of two thiol groups per one molecule of polyvinyl butyral.

[0147] (Preparation of Vehicle 1) 5 parts by mass of cellulose compound (1a) and 4.35 parts by mass of polyvinyl butyral compound (1b) were dissolved in 60 parts by mass of isobornyl acetate solvent, and the solution was transferred to a glass flask reaction vessel. After nitrogen substitution, 0.1 parts by mass of azobisisobutyronitrile as a radical generator was added to the solution, and the reaction was carried out at 80°C for 3 hours with stirring to obtain Vehicle 1 containing Polymer Compound 1. Here, the cellulose compound (1a) and the polyvinyl butyral compound (1b) have the same molar ratio. Vehicle 1 contains 13.5% by mass of Polymer Compound 1. Here, Polymer Compound 1 is a mixture of a polymer compound in which the cellulose compound (1a) and the polyvinyl butyral compound (1b) are bonded, unreacted ethyl cellulose, and unreacted polyvinyl butyral, and these mixtures are referred to as Polymer Compound 1 in the examples. The δh of the HSP of isobornyl acetate is 3.0 MPa. ０．５ is.

[0148] When the synthesized polymer compound 1 was analyzed by FT-IR and 1H-NMR, the presence of an -S- bond was confirmed, and the target structure was obtained. Furthermore, the mass average molecular weight (Mw: standard polystyrene equivalent value by GPC) of polymer compound 1 was measured. The HSP δh of polymer compound 1 was calculated using HSPiP version 5 from the HSP values ​​of the solvents in which the resin was soluble, after a test in which the resin was dissolved in 20 solvents with known HSP values. The result was 7.61 MPa. ０．５ It was.

[0149] (Preparation of Vehicle 2) Polymer compound 2 synthesized from a cellulose-based compound (2a) and a polyvinyl butyral-based compound (2b) was also synthesized in the same manner as polymer compound 1 to obtain vehicle 2. The content of polymer compound 2 in vehicle 2 was 13.5 mass%. Like polymer compound 1, polymer compound 2 contains a mixture of a polymer compound in which a cellulose-based compound (2a) and a polyvinyl butyral-based compound (2b) are bonded together, as well as unreacted ethyl cellulose and unreacted polyvinyl butyral, and in the examples, this mixture is referred to as polymer compound 2.

[0150] Similarly to polymer compound 1, the synthesized polymer compound 2 was analyzed by FT-IR and 1H-NMR, and -S- bonds were confirmed, confirming that the target structure was obtained. Furthermore, the mass average molecular weight (Mw: standard polystyrene equivalent value by GPC) of polymer compound 2 was measured. The δh of the HSP of polymer compound 2 was calculated using the same method as for polymer compound 1, and was found to be 7.63 MPa. ０．５ It was.

[0151] (Preparation of Vehicle 3) 5 parts by mass of cellulose compound (1a) and 4.35 parts by mass of polyvinyl butyral compound (1b) were dissolved in 60 parts by mass of dihydroterpineol solvent, and the solution was transferred to a glass flask reaction vessel. After nitrogen substitution, 0.1 parts by mass of azobisisobutyronitrile as a radical generator was added to the solution, and the reaction was carried out at 80°C for 3 hours with stirring to obtain Vehicle 3 containing Polymer Compound 3. Here, the cellulose compound (1a) and the polyvinyl butyral compound (1b) have the same molar ratio. Vehicle 3 contains 13.5% by mass of Polymer Compound 3. Here, Polymer Compound 3 is a mixture of a polymer compound in which the cellulose compound (1a) and the polyvinyl butyral compound (1b) are bonded, unreacted ethyl cellulose, and unreacted polyvinyl butyral. In the examples, these mixtures are referred to as Polymer Compound 3. The δh of the HSP of dihydroterpineol is 6.7 MPa. ０．５ is.

[0152] Similarly to polymer compound 1, the synthesized polymer compound 3 was analyzed by FT-IR and 1H-NMR, and -S- bonds were confirmed, confirming that the target structure was obtained. Furthermore, the mass average molecular weight (Mw: standard polystyrene equivalent value by GPC) of polymer compound 3 was measured. The δh of the HSP of polymer compound 3 was calculated using the same method as for polymer compound 1, and was found to be 7.62 MPa. ０．５ It was.

[0153] Table 1 shows the characteristics of the cellulose compounds (1a) and (2a) and the polyvinyl acetal compounds (1b) and (2b) used in the polymer compounds 1 to 3 contained in the vehicles 1 to 3, and Table 2 shows the mass average molecular weights of the polymer compounds 1 to 3, and the names and δh values ​​of the organic solvents contained in the vehicles 1 to 3.

[0154]

[0155]

[0156] [Example 1] In Example 1, a conductive paste was prepared using vehicle 1 as follows, and the resulting conductive paste was used to evaluate physical properties such as sheet attack, surface roughness, and dry film density. Here, vehicle 1 contains polymer compound 1, in which a cellulose compound and a polyvinyl acetal compound are bonded by sulfur atoms, as a binder resin, and the hydrogen bond term δh of the Hansen solubility parameter is 3.0 MPa. ０．５ (6.5 MPa ０．５ In Polymer Compound 1, the molar ratio of sulfur atoms to the cellulose-based compound is 1.

[0157] <Preparation of Conductive Paste> 47 mass% of Ni powder, 4.7 mass% of ceramic powder, 26.67 mass% of vehicle 1, 0.4 mass% of an anionic dispersant of an amide compound of amino acid and fatty acid (hereinafter, may be referred to as "dispersant A"), and the remaining 21.23 mass% of an organic solvent (isobornyl acetate) were blended together to make a total of 100 mass%, and these materials were mixed to prepare the conductive paste of Example 1.

[0158] (Conductive Powder) Ni powder (number average particle diameter of 0.2 μm as measured by SEM) was used as the conductive powder used to prepare the conductive paste.

[0159] (Ceramic Powder) The ceramic powder used to prepare the conductive paste was barium titanate (BaTiO ３ The number average particle size measured by SEM was 0.05 μm.

[0160] [Evaluation Method] (Sheet attack, surface roughness of dried film, dry film density) The sheet attack of the prepared conductive paste, the surface roughness of the dried film obtained by drying the conductive paste, and the dry film density were evaluated as follows.

[0161] <Sheet attack> 2 μm thick green sheet (barium titanate (BT, BaTiO ３The conductive paste prepared was printed onto a green sheet (containing polyvinyl butyral resin) and dried at 80°C for 3 minutes. Immediately after drying, the surface of the green sheet opposite the printed surface was observed under a microscope to check for the presence or absence of the swelling phenomenon specific to sheet attack. If no swelling phenomenon was observed, it was evaluated as ○ (good), and if it was observed, it was evaluated as × (bad).

[0162] <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 (Keyence VK-X120) in accordance with the ISO 25178 standard. The smaller the surface roughness Sa (arithmetic mean height), the smoother the surface of the dried film.

[0163] <Dry Film Density> The prepared conductive paste was placed on a PET film and spread to a length of approximately 100 mm using an applicator with a width of 50 mm and a gap of 125 μm. The obtained PET film was dried at 120° C. for 40 minutes to form a dried body, which was then cut into four pieces of 2.54 cm (1 inch) square. The PET film was peeled off, and the thickness and weight of each of the four dried films were measured to calculate the dry film density (average value).

[0164] Comparative Example 1 In Comparative Example 1, a conductive paste was prepared in the same manner as in Example 1 using Vehicle 2, and the obtained conductive paste was used to evaluate physical properties such as sheet attack, surface roughness, and dry film density. Here, Vehicle 2 contains, as a binder resin, polymer compound 2 in which a cellulose compound and a polyvinyl acetal compound are bonded by sulfur atoms, and the hydrogen bond term δh of the Hansen solubility parameter is 3.0 MPa. ０．５ (6.5 MPa ０．５ In Polymer Compound 2, the molar ratio of sulfur atoms to the cellulose-based compound is 2.

[0165] <Preparation of Conductive Paste and Evaluation of Physical Properties> A conductive paste according to Comparative Example 1 was prepared in the same manner as in Example 1, except that Vehicle 2 was used, and the sheet attack, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0166] Comparative Example 2 is an example in which a conductive paste was prepared in the same manner as in Example 1 using Vehicle 3, and the obtained conductive paste was used to evaluate physical properties such as sheet attack, surface roughness, and dry film density. Here, Vehicle 3 contains, as a binder resin, polymer compound 3 in which a cellulose compound and a polyvinyl acetal compound are bonded by sulfur atoms, and the hydrogen bond term δh of the Hansen solubility parameter is 6.7 MPa. ０．５ As an organic solvent, the polymer compound 3 contains dihydroterpineol of the formula (I). In the polymer compound 3, the molar ratio of sulfur atoms to the cellulose compound is 3.

[0167] A conductive paste according to Comparative Example 2 was prepared in the same manner as in Example 1, except that dihydroterpineol was used as the vehicle 3 and the remaining organic solvent, and the sheet attack, surface roughness of the dried film, and density of the dried film were evaluated in the same manner as in Example 1.

[0168] Comparative Example 3 is an example in which a conductive paste was prepared using ethyl cellulose and polyvinyl butyral resin without using any of the vehicles 1 to 3 and without including any polymer compound, and the obtained conductive paste was used to evaluate physical properties such as sheet attack, surface roughness, and dry film density. In addition, the conductive paste was prepared using a solvent having a hydrogen bond term δh of the Hansen solubility parameter of 3.0 MPa. ０．５ (6.5 MPa ０．５ Isobornyl acetate (see below) was used as the organic solvent.

[0169] (Preparation of Vehicle 4a) Five parts by mass of ethyl cellulose ("Ethocel STD-100" manufactured by Dow Chemical) was dissolved in 30 parts by mass of isobornyl acetate to prepare an organic vehicle 4a.

[0170] (Preparation of Vehicle 4b) Vehicle 4b was prepared by dissolving 4.35 parts by mass of polyvinyl butyral resin (BM-SZ manufactured by Sekisui Chemical Co., Ltd.) in 30 parts by mass of isobornyl acetate.

[0171] (Preparation of Vehicle 4) Organic vehicle 4 was prepared by mixing equal amounts of organic vehicle 4a and organic vehicle 4b.

[0172] <Preparation of Conductive Paste> 47 mass % of Ni powder, 4.7 mass % of ceramic powder, 26.67 mass % of Vehicle 4, 0.4 mass % of Dispersant A, and the remaining 21.23 mass % of organic solvent (isobornyl acetate) were blended together to make a total of 100 mass %, and these materials were mixed to prepare a conductive paste according to Comparative Example 3.

[0173] The prepared conductive paste was evaluated in the same manner as in Example 1 for sheet attack, surface roughness of the dried film, and density of the dried film.

[0174] Comparative Example 4 is an example in which a conductive paste was prepared using ethyl cellulose and polyvinyl butyral resin without using any of the vehicles 1 to 3 and without including any polymer compound, and the obtained conductive paste was used to evaluate physical properties such as sheet attack, surface roughness, and dry film density. In addition, the conductive paste was prepared using a solvent having a hydrogen bond term δh of the Hansen solubility parameter of 6.7 MPa. ０．５ Dihydroterpineol was used as the organic solvent.

[0175] (Preparation of Vehicle 5a) Five parts by mass of ethyl cellulose (Ethocel STD-100 manufactured by Dow Chemical) was dissolved in 30 parts by mass of dihydroterpineol to prepare an organic vehicle 5a.

[0176] (Preparation of Vehicle 5b) Vehicle 5b was prepared by dissolving 4.35 parts by mass of polyvinyl butyral resin (BM-SZ manufactured by Sekisui Chemical Co., Ltd.) in 30 parts by mass of dihydroterpineol.

[0177] (Preparation of Vehicle 5) Organic vehicle 5 was prepared by mixing equal amounts of vehicle 5a and organic vehicle 5b.

[0178] <Preparation of Conductive Paste> 47 mass% of Ni powder, 4.7 mass% of ceramic powder, 26.67 mass% of Vehicle 5, 0.4 mass% of Dispersant A, and the remaining 21.23 mass% of organic solvent (dihydroterpineol) were blended together to make a total of 100 mass%, and these materials were mixed to prepare a conductive paste according to Comparative Example 4.

[0179] The prepared conductive paste was evaluated in the same manner as in Example 1 for sheet attack, surface roughness of the dried film, and density of the dried film.

[0180] Table 3 shows the names of the organic solvents contained in the conductive pastes of Example 1 and Comparative Examples 1 to 4, the δh values, the types of binder resins, and the evaluation results of sheet attack, surface roughness, and dry film density.

[0181]

[0182] [Evaluation Results] The dried film formed using the conductive paste of Example 1 had a surface roughness Sa (arithmetic mean height) of 90 nm, the lowest compared to the comparative examples, as shown in Table 3. The conductive paste of Example 1 also had a dry film density of 5.51 g / cm ３ Furthermore, the conductive paste of Example 1 does not cause sheet attack. In other words, the conductive paste of Example 1 does not cause sheet attack on the green sheet, and can form a dry film with good smoothness and dry film density.

[0183] On the other hand, in the case of the conductive paste of Comparative Example 1, in which the number of functional groups in polymer compound 2 was 2, the surface roughness and dry film density of the obtained dried film were both inferior to those of Example 1. In the case of the conductive paste of Comparative Example 3, which used common ethyl cellulose and polyvinyl butyral resin as the binder resin and isobornyl acetate, a solvent that does not cause sheet attack, no sheet attack occurred, but the surface roughness was the worst among Example 1 and Comparative Examples 1 to 4. In the case of the conductive paste of Comparative Example 4, which used common ethyl cellulose and polyvinyl butyral resin as the binder resin and dihydroterpineol, sheet attack occurred, and the surface roughness and dry film density were also inferior to those of Example 1.

[0184] The conductive paste according to the present embodiment, which uses finely divided conductive powders or ceramic powders, can provide a conductive paste that does not cause sheet attack on green sheets, has a smooth dried film, and has excellent adhesion. 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.

[0185] 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 vehicle comprising 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, and the molar ratio of the sulfur atom contained in the polymer compound to the cellulose-based compound is 0.3 to 1.7, and the hydrogen bond term δh of the Hansen solubility parameter of the organic solvent is 6.5 MPa ０．５ The vehicle described below.

2. The hydrogen bonding term δh of the Hansen solubility parameter of the polymer compound is 6.5 to 8.5 MPa ０．５ The vehicle according to claim 1, wherein the vehicle is as described above.

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, 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 vehicle according to claim 1 or 2.

4. 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. The vehicle according to claim 3.

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 polymer compound is a thiol-ene reactant of the first esterification reactant and the second esterification reactant. The vehicle according to claim 1 or 2.

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

7. A vehicle according to claim 1 or 2, a conductive powder, and a conductive paste containing a ceramic powder, wherein a hydrogen bonding term δh of a Hansen solubility parameter of an organic solvent in the conductive paste is 6.5 MPa ０．５ or less, the conductive paste.

8. The number average particle diameter of the conductive powder is 0.05 μm or more and 1.0 μm or less. The conductive paste according to claim 7.

9. The ceramic powder contains barium titanate. The conductive paste according to claim 7.

10. 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 7.

11. The content of the ceramic powder is 1% by mass or more and 20% by mass or less. The conductive paste according to claim 7.

12. It is for an internal electrode of a multilayer ceramic component. The conductive paste according to claim 7.

13. An electronic component formed using the conductive paste according to claim 7.

14. It has 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 7. A multilayer ceramic capacitor.

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