JP2019157089A - Method for producing organic vehicle and method for producing conductive paste - Google Patents

Abstract

To provide a conductive paste that has a high dry film density, suppresses a viscosity change with time, and has excellent viscosity stability, and an organic vehicle for use therein.SOLUTION: The present invention provides a method for producing an organic vehicle or the like, including mixing an acetal resin, a cellulose resin, an amine dispersant, and an organic solvent at 40°C or more and 120°C or less, where, the amine dispersant is mixed in an amount of 9 pts.mass or more and 440 pts.mass or less relative to the acetal resin 100 pts.mass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing an organic vehicle and a method for producing a conductive paste.

  With the downsizing and high performance of electronic devices such as mobile phones and digital devices, miniaturization and high capacity of electronic components including multilayer ceramic capacitors are desired. Multilayer ceramic capacitors have a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked. By reducing the thickness of these dielectric layers and internal electrode layers, the size and capacity can be reduced. Can be planned.

The multilayer ceramic capacitor is manufactured, for example, as follows. First, on the surface of a dielectric green sheet containing dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, a conductive paste for internal electrodes is printed (coated) with a predetermined electrode pattern and dried. To form a dry film. Next, a laminated body is obtained by laminating the dry film and the green sheet alternately. Next, this laminated body is integrated by thermocompression bonding to form a crimped body. The pressure-bonded body is cut and subjected to a deorganic binder treatment in an oxidizing atmosphere or an inert atmosphere, and then fired to obtain a fired chip. Next, an external electrode paste is applied to both ends of the fired chip, and after firing, the surface of the external electrode is subjected to nickel plating or the like to obtain a multilayer ceramic capacitor.

  Generally, the conductive paste used for forming the internal electrode layer includes a conductive powder, a ceramic powder, a binder resin, and an organic solvent. In addition, the conductive paste may contain a dispersant in order to improve the dispersibility of the conductive powder and the like. As the internal electrode layer becomes thinner in recent years, the conductive powder also tends to have a smaller particle size. When the particle size of the conductive powder is small, the specific surface area of the particle surface increases, so that the surface activity of the conductive powder (metal powder) increases and aggregation tends to occur, resulting in reduced dispersibility and viscosity. Degradation of characteristics may occur.

  On the other hand, when the internal electrode layer is thinned, it is required that the density of the dry film obtained by printing the conductive paste for internal electrodes on the surface of the derivative green sheet and drying it is high.

  For example, in Patent Document 1, after mixing and reacting two kinds of resin components in an organic solvent, the organic solvent is removed and dried to form a reactive resin, which is then used again in a paste. A method of producing a vehicle by dissolving in an organic solvent is shown. According to Patent Document 1, it is shown that by using the vehicle thus obtained, the dry film density is improved and the particle dispersibility is also improved.

International Publication No. 2017/014295

  However, in the method described in Patent Document 1, a process for producing a reactive resin is complicated, requires a long process, and causes an increase in cost. Therefore, a process that can be produced more simply has been demanded.

  In view of such circumstances, the present invention provides a conductive paste having a high dry film density, little change in viscosity over time, and excellent viscosity stability, and an organic vehicle suitably used for the conductive paste. With the goal.

  In the first aspect of the present invention, an acetal resin, a cellulose resin, an amine dispersant, and an organic solvent are mixed at a temperature of 40 ° C. or higher and 120 ° C. or lower, and the amine dispersant is an acetal. A method for producing an organic vehicle is provided, which is mixed in an amount of 9 to 440 parts by mass with respect to 100 parts by mass of the system resin.

  In the second aspect of the present invention, an acetal resin and an organic solvent are mixed at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a first mixture, and the cellulose resin and the organic solvent are mixed at 40 ° C. or higher and 120 ° C. Mixing at a temperature not higher than ° C. to obtain a second mixture, and mixing the first mixture, the second mixture, and the amine dispersant at a temperature not lower than 40 ° C. and not higher than 120 ° C. A method for producing an organic vehicle is provided in which an amine dispersant is mixed in an amount of 9 parts by mass or more and 440 parts by mass or less with respect to 100 parts by mass of an acetal resin.

（ただし、式（１）中、Ｒ_１は炭素数８〜１６のアルキル基、アルケニル基、又は、アルキニル基を表し、Ｒ_２はオキシエチレン基、オキシプロピレン基、又は、メチレン基を表し、Ｒ_３はオキシエチレン基、又は、オキシプロピレン基を表し、Ｒ_２及びＲ_３は、同一でもよく、又は、異なっていてもよい。式（１）中のＮ原子と、Ｒ_２及びＲ_３中のＯ原子とは直接結合せず、Ｙは０〜２の数であり、Ｚは１〜２の数である。） In the method for producing the organic vehicle, the amine dispersant preferably has a structure represented by the following general formula (1).

(Wherein (1), _{R 1} represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, _{R 2} represents an oxyethylene group, oxypropylene group, or a methylene radical, R ₃ represents an oxyethylene group or an oxypropylene group, and R ₂ and R ₃ may be the same or different, and the N atom in formula (1) and R ₂ and R ₃ (It is not directly bonded to the O atom, Y is a number from 0 to 2, and Z is a number from 1 to 2.)

  The organic solvent has a boiling point of 100 ° C. or higher and 300 ° C. or lower, and preferably has solubility in both the acetal resin and the cellulose resin.

  In a third aspect of the present invention, obtaining an organic vehicle by the method of the first aspect or the method of the second aspect, mixing a conductive powder, a ceramic powder, and the organic vehicle; A method for producing a conductive paste is provided.

  The amine-based dispersant is preferably contained in an amount of 0.11% by mass to 5.5% by mass with respect to 100% by mass of the conductive paste. The conductive powder is preferably at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. Moreover, it is preferable that the average particle diameter of electroconductive powder is 0.05 micrometer or more and 1.0 micrometer or less. The ceramic powder is preferably a perovskite oxide. Moreover, it is preferable that the average particle diameter of a ceramic powder is 0.01 micrometer or more and 0.5 micrometer or less.

  The conductive paste of the present invention has little change in viscosity over time, is excellent in viscosity stability, and is excellent in dry film density after coating. Further, the organic vehicle of the present invention is excellent in resin compatibility and can be suitably used for the conductive paste.

FIG. 1 is a diagram illustrating an example of a method for producing an organic vehicle according to the present embodiment. FIG. 2 is a diagram showing another example of the method for producing an organic vehicle according to the present embodiment. FIG. 3 is a diagram illustrating an example of a method for producing a conductive paste according to the present embodiment. FIG. 4 is a perspective view and a cross-sectional view illustrating the multilayer ceramic capacitor according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Further, in the drawings, in order to make each configuration easy to understand, a part of the configuration is emphasized or a part of the configuration is simplified, and the actual configuration, shape, scale, or the like may be different. In addition, this invention is not restrict | limited to the following embodiment. Various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention.

1. Organic Vehicle Manufacturing Method (1) First Embodiment [Mixing Step (Step S10)]
FIG. 1 is a diagram illustrating an example of a method for producing an organic vehicle according to the present embodiment. As shown in FIG. 1, the method for producing an organic vehicle according to the present embodiment comprises mixing an acetal resin, a cellulose resin, an amine dispersant, and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower ( Step S10).

  Although the details of the conductive paste produced using the organic vehicle obtained by the mixing step (step S10) are unknown, the dispersibility and viscosity stability of the conductive paste are improved. Moreover, in the conductive paste containing an acetal resin and a cellulose resin, the compatibility of these resins may be a problem, but the organic vehicle obtained in this embodiment is compatible with these resins. Will improve. Hereinafter, each material will be described.

(Cellulosic resin)
The cellulose resin is not particularly limited, and a known cellulose resin (cellulose derivative) used as a binder resin in the conductive paste can be used. Examples of the cellulose-based resin include ethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, methyl cellulose, propyl cellulose, and acetyl cellulose. Among these, it is preferable to contain an ethyl cellulose resin (hereinafter also referred to as “EC resin”) from the viewpoints of solubility in a solvent and combustion decomposability. In addition, 1 type may be used for a cellulose resin, and 2 or more types may be used for it.

(Acetal resin)
The acetal resin is not particularly limited, and a known acetal resin used as a binder resin can be used. Examples of the acetal resin include polyvinyl butyral resin (hereinafter also referred to as “PBV resin”). When an acetal resin is used, the adhesiveness between the conductive paste (internal electrode) and the dielectric green sheet can be improved. In addition, 1 type may be used for an acetal type resin, and 2 or more types may be used for it.

  In the mixing step (step S10), other resins (eg, acrylic resins) other than the cellulose resin and the acetal resin may be further used as long as the effects of the present invention are not impaired.

(Amine dispersant)
As a result of studying various additives with respect to the additive used for the conductive paste, the inventors have improved the compatibility between the resins by adding an amine-based dispersant, and the conductive paste over time. It has been found that there is little change in viscosity, excellent dispersibility of Ni powder, and excellent dry film density after coating. Hereinafter, the dispersant used in the present embodiment will be described.

  It does not specifically limit as an amine type dispersing agent, The well-known amine type dispersing agent used as a dispersing agent in an electrically conductive paste can be used. The amine-based dispersant is preferably an amine-based dispersant represented by the following general formula (1), for example. In addition, one type of amine dispersant may be used, or two or more types may be used.

（ただし、上記式（１）中、Ｒ_１は炭素数８〜１６のアルキル基、アルケニル基、又は、アルキニル基を表し、Ｒ_２はオキシエチレン基、オキシプロピレン基、又は、メチレン基を表し、Ｒ_３はオキシエチレン基、又は、オキシプロピレン基を表し、Ｒ_２及びＲ_３は、同一でもよく、又は、異なっていてもよい。また、式（１）中のＮ原子と、Ｒ_２及びＲ_３中のＯ原子とは直接結合せず、Ｙは０〜２の数であり、Ｚは１〜２の数である。）

(However, in the above formula (1), _{R 1} represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, _{R 2} represents an oxyethylene group, oxypropylene group, or a methylene group, R ₃ represents an oxyethylene group or an oxypropylene group, and R ₂ and R ₃ may be the same or different, and the N atom in the formula (1) and R ₂ and R 3 ₍ It is not directly bonded to the O atom in ₃ , Y is a number from 0 to 2, and Z is a number from 1 to 2.)

  The amine-based dispersant is preferably a tertiary amine or a secondary amine, as shown by the general formula (1), and has a structure in which an amine group and one or two oxyethylene groups are bonded. It is preferable to have.

In the above formula (1), _{R 1} represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group. When the carbon number of R ₁ is in the above range, the powder in the resulting conductive paste has sufficient dispersibility and excellent solubility in a solvent. R ₁ is preferably a linear hydrocarbon group.

In the above formula (1), R ₂ represents an oxyethylene group, an oxypropylene group, or a methylene group, R ₃ represents an oxyethylene group or an oxypropylene group, and R ₂ and R ₃ may be the same. May be different or different. Further, the N atom in the formula (1) and the O atom in R ₂ and R ₃ are not directly bonded, Y is a number from 0 to 2, and Z is a number from 1 to 2.

For example, when R ₂ is an oxyalkylene group represented by — (AO) _Y —, the O atom in the oxyalkylene group is bonded to the H atom adjacent to R ₂ . Further, when R ₂ is a methylene group, R ₂ is represented by — (CH ₂ ) _Y —, and when Y is 1 to 2, a methyl group (—CH ₃ ) or ethyl together with the adjacent H element The group (—CH ₂ —CH ₃ ) is formed. When R ₃ is an oxyalkylene group represented by — (AO) _z —, the O atom in the oxyalkylene group is bonded to an H atom adjacent to R ₃ .

  In the above formula (1), when Y is 0, the amine-based additive is a secondary amine having an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms and one hydrogen group. When Y is 0 and Z is 2, the amine dispersant is an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms, one hydrogen group, and one polyoxyethylene group. Or it becomes the secondary amine comprised from a polyoxypropylene group.

  In the formula (1), when Y is 1, the amine dispersant is a tertiary amine having an alkyl group, an alkenyl group, or an alkynyl group having 8 to 16 carbon atoms. When Y is 2, the amine dispersant is a tertiary amine having an alkyl group having 8 to 16 carbon atoms, an alkenynyl group, or an alkynyl group, and at least one polyoxyethylene group or polyoxypropylene group. It becomes.

  As the amine-based additive represented by the above formula (1), for example, a commercially available product that satisfies the above characteristics can be selected and used. Moreover, you may manufacture the said amine-type additive so that the said structure may be satisfy | filled using a conventionally well-known manufacturing method.

(Organic solvent)
It does not specifically limit as an organic solvent, The well-known organic solvent which can melt | dissolve the said binder resin can be used. Examples of organic solvents include dihydroterpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate and isobornyl isobutyrate, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, and the like. And terpene solvents such as terpineol and dihydroterpineol, and hydrocarbon solvents such as tridecane, nonane and cyclohexane. In addition, the organic solvent may use 1 type and may use 2 or more types.

  Moreover, it is preferable that the boiling point of an organic solvent is 100 degreeC or more and 300 degrees C or less, and 120 degreeC or more and 260 degrees C or less are more preferable.

(Mixing ratio)
The mixing ratio of each material will be described below. In addition, the mixing ratio with respect to the whole mixture obtained by mixing the following each material is equivalent to the content ratio of each material (raw material) with respect to the whole organic vehicle obtained.

  The total mixing ratio of the acetal resin and the cellulose resin is preferably 5% by mass or more and 25% by mass or less, more preferably 8% by mass, with respect to the entire mixture (total amount) obtained by mixing each material. The content is 18% by mass or less.

  The mixing ratio of the acetal resin (eg, PVB resin) and the cellulose resin (eg, EC resin) is preferably 50 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the cellulose resin. More preferably, it is at least 90 parts by weight. When the ratio exceeds 100 parts by weight, the printability may be deteriorated and the dry film density may not be improved. When the amount is less than 50 parts by weight, the adhesion with the green sheet during the MLCC process is deteriorated, and it may be difficult to produce a laminate.

  The mixing ratio of the amine dispersant is, for example, 9 parts by mass or more and 440 parts by mass or less, preferably 15 parts by mass or more and 420 parts by mass or less, with respect to 100 parts by mass of the acetal resin. More preferably, it is 40 to 400 mass parts. When the amine dispersant is included in the above range, the compatibility between the acetal resin and the cellulose resin is improved. In addition, when the amine dispersant is included in the above range, the viscosity change with time can be suppressed when used in the conductive paste, the viscosity stability can be improved, or the film can have a high dry film density. it can.

  The mixing ratio of the amine-based dispersant is, for example, 0.45% by mass or more and 22% by mass, preferably 0.75% by mass or more and 21% by mass with respect to the entire mixture (total amount) obtained by mixing each material. % Or less, preferably 0.5% by mass or more and 15% by mass or less, and more preferably 0.8% by mass or more and 8% by mass or less. When the amine dispersant is included in the above range, the compatibility between the acetal resin and the cellulose resin is improved. Moreover, when it uses for an electrically conductive paste, a viscosity change with time can be suppressed, viscosity stability can be improved, or it can have a high dry film density.

  The mixing ratio of the amine-based dispersant is, for example, 6.45 parts by mass or more and 315 parts by mass or less, and preferably 10.75 parts by mass or more and 300 parts by mass with respect to 100 parts by mass of the total mixing amount of the cellulose resin. Part or less, more preferably 28 parts by mass or more and 285 parts by mass or less.

  The mixing ratio of the amine dispersant is, for example, 3.75 parts by mass or more and 185 parts by mass or less, preferably 6.25 parts by mass with respect to 100 parts by mass of the total mixing amount of the acetal resin and the cellulose resin. Part or more and 175 parts by mass or less, and more preferably 16.5 parts by mass or more and 165 parts by mass or less.

  Further, when the organic vehicle obtained by the manufacturing method of the present embodiment is used for a conductive paste, the mixing ratio of the amine dispersant is, for example, 0.11% by mass or more with respect to 100% by mass of the conductive paste. 5.50% by mass or less, preferably 0.19% by mass to 5.25% by mass, and more preferably 0.5% by mass to 5% by mass.

  The mixing ratio of the organic solvent is preferably 40% by mass or more and 95% by mass or less, and more preferably 65% by mass or more and 95% by mass or less, with respect to the entire mixture (total amount) obtained by mixing each material. is there. When the content of the organic solvent is within the above range, the conductivity and dispersibility are excellent.

(Mixing temperature)
In the mixing step (step S10), the above-described materials are mixed (heated and mixed) at a temperature of 40 ° C. or higher and 120 ° C. or lower, preferably 50 ° C. or higher and 100 ° C. or lower. When the temperature is lower than 40 ° C., the effect of the present invention cannot be obtained. On the other hand, when the temperature exceeds 120 ° C., the organic solvent is volatilized or alteration due to oxidation or the like occurs, which is not preferable. Moreover, it is preferable that temperature is the temperature below the boiling point of the organic solvent used for this embodiment.

(Other mixing conditions)
The heating time is not particularly limited but is preferably 1 hour or more and 10 hours or less. When the heating time is less than 1 hour, the mixing effect may not be obtained. Moreover, when heating time exceeds 10 hours, there is no improvement of an effect in particular and it is disadvantageous in cost.

  Moreover, as a mixing method, it can stir using the motor with a rotary blade by electric or air operation, for example. The stirring speed is not particularly limited, but is, for example, about 50 rpm to 150 rpm. The other mixing conditions are not particularly limited, and normal mixing conditions can be used.

(2) Second Embodiment FIG. 2 is a diagram showing another example of a method for producing an organic vehicle according to this embodiment. As shown in FIG. 2, another manufacturing method of the organic vehicle according to the present embodiment is to obtain a first mixture by mixing an acetal resin and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower (first step). 1 mixing step: Step S1), mixing a cellulose resin and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a second mixture (second mixing step: Step S2), Mixing the first mixture, the second mixture, and the amine dispersant at a temperature of 40 ° C. or higher and 120 ° C. or lower (third mixing step: step S10) may be provided. Hereinafter, each step will be described.

[First mixing step (step S1)]
In the first mixing step (step S1), the acetal resin and the organic solvent are mixed at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a first mixture. Since the preferred types of the acetal resin and the organic solvent are the same as those in the first embodiment, the description thereof is omitted.

  The mixing ratio of the acetal resin and the organic solvent is not particularly limited as long as the acetal resin is sufficiently dissolved in the organic solvent. For example, the acetal resin is not less than 5% by mass with respect to the entire first mixture. Mix below mass%.

  Moreover, the temperature at the time of mixing an acetal resin and an organic solvent is 40 degreeC or more and 120 degrees C or less.

[Second Mixing Step (Step S2)]
In the second mixing step (step S2), the cellulose resin and the organic solvent are mixed at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a second mixture. Note that the second mixing step (step S2) may be performed simultaneously with the first mixing step (step S1), or may be performed before or after the first mixing step (step S1). Since the preferred types of the cellulose resin and the organic solvent are the same as those in the first embodiment, the description is omitted. The type of the organic solvent may be the same as or different from the organic solvent used in the first mixing step.

  The mixing ratio of the cellulosic resin and the organic solvent is not particularly limited as long as the cellulosic resin is sufficiently dissolved in the organic solvent. For example, the cellulosic resin is 5% by mass or more and 30% by mass or more with respect to the entire second mixture. Mix below mass%.

  Moreover, the temperature at the time of mixing a cellulose resin and an organic solvent is 40 degreeC or more and 120 degrees C or less.

[Third mixing step (step S10)]
Next, the first mixture, the second mixture, and the amine dispersant are mixed at a temperature of 40 ° C. or higher and 120 ° C. or lower (third mixing step: step S10). As described above, when the resin component is previously heated and mixed in each organic solvent, each material can be more uniformly mixed in the third mixing step (step S10).

  The mixing ratio of the first mixture, the second mixture, and the amine-based dispersant is in the same range as the mixing ratio with respect to the entire mixture obtained by mixing the materials in the first embodiment. The description is omitted because it may be mixed so that In addition, the mixing ratio with respect to the whole mixture obtained by mixing the following each material is equivalent to the content ratio of each material (raw material) with respect to the whole organic vehicle obtained.

  Moreover, since the mixing conditions are the same as those in the first embodiment, the description is omitted.

2. Method for Producing Conductive Paste FIG. 3 is a diagram illustrating an example of a method for producing a conductive paste according to the present embodiment. As described above, the method for producing a conductive paste according to the present embodiment is a step of obtaining an organic vehicle by a mixing step (step S10), mixing a conductive powder, a ceramic powder, and the obtained organic vehicle ( Step S20). The obtained conductive paste contains a conductive powder, a ceramic powder, a dispersant, a binder resin, and an organic solvent. In addition, the manufacturing method of an organic vehicle can be obtained by the method including at least a mixing process (step S10), and may be obtained by the manufacturing method of the first embodiment described above, or by the manufacturing method of the second embodiment. May be obtained. Hereinafter, each material used for the conductive paste and the obtained conductive paste will be described.

(Conductive powder)
The conductive powder is not particularly limited, and a metal powder can be used. For example, at least one powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, Ni or a powder of an alloy thereof is preferable from the viewpoint of conductivity, corrosion resistance, and cost. As the Ni alloy, for example, an alloy of Ni and at least one element selected from the group consisting of Mn, Cr, Co, Al, Fe, Cu, Zn, Ag, Au, Pt, and Pd is used. it can. The Ni content in the Ni alloy is, for example, 50% by mass or more, and preferably 80% by mass or more. Further, the Ni powder may contain about several hundred ppm of S in order to suppress rapid gas generation due to partial thermal decomposition of the binder resin during the debinding process.

  The average particle size of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When the average particle diameter of the conductive powder is in the above range, it can be suitably used as a paste for an internal electrode of a thin-film laminated ceramic capacitor, and for example, the smoothness of the dry film and the dry film density are improved. The average particle diameter is a value obtained from observation with a scanning electron microscope (SEM), and is obtained by measuring the particle diameter of each of a plurality of particles from an image observed with a SEM at a magnification of 10,000 times. Is the average value.

  The content of the conductive powder is preferably 30% by mass or more and less than 70% by mass, and more preferably 40% by mass or more and 60% by mass or less, with respect to the total amount of the conductive paste. When content of electroconductive powder is the said range, it is excellent in electroconductivity and dispersibility.

(Ceramic powder)
The ceramic powder is not particularly limited. For example, in the case of a paste for internal electrodes 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 oxides containing Ba and Ti, and preferably barium titanate (BaTiO ₃ ).

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as a subcomponent may be used. Examples of the oxide include Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, and oxides of one or more rare earth elements. As such a ceramic powder, for example, a ceramic powder of a perovskite oxide ferroelectric material in which Ba atoms and Ti atoms of barium titanate (BaTiO ₃ ) are substituted with other atoms, for example, Sn, Pb, Zr, etc. Can be mentioned.

In the conductive paste for the internal electrode, a powder having the same composition as the dielectric ceramic powder constituting the green sheet of the multilayer ceramic capacitor may be used. Thereby, the generation of cracks due to the shrinkage mismatch at the interface between the dielectric layer and the internal electrode layer in the sintering process is suppressed. Examples of such ceramic powder include ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth element) ₂ O ₃ , TiO ₂ , and Nd ₂ O _{3 in addition to} the above. An oxide is mentioned. In addition, 1 type may be used for ceramic powder and 2 or more types may be used for it.

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

  The content of the ceramic powder is preferably 1 part by mass or more and 30 parts by mass or less, and more preferably 3 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the conductive powder.

  The content of the ceramic powder is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, with respect to the total amount of the conductive paste. When content of electroconductive powder is the said range, it is excellent in electroconductivity and dispersibility.

(Organic vehicle)
The organic vehicle is obtained by the mixing step (step S10) as described above. The organic vehicle includes an acetal resin, a cellulose resin, an amine dispersant, and an organic solvent. The content of the whole organic vehicle is preferably 10% by mass or more and 40% by mass or less, more preferably 20% by mass or more and 30% by mass or less, with respect to the total amount of the conductive paste, with respect to the total amount of the conductive paste. .

  The content of the amine dispersant is preferably 0.11% by mass or more and 5.50% by mass or less, more preferably 0.19% by mass or more and 5.5% by mass or less with respect to the total amount of the conductive paste (100% by mass). It is 25 mass% or less, More preferably, it is 0.5 mass% or more and 5 mass% or less.

(Other materials)
In the conductive paste, for example, an acid dispersant containing a higher fatty acid, a polymer surfactant, or the like, a cationic dispersant other than the acid dispersant, or a nonionic dispersion may be used, as long as the effects of the present invention are not impaired. Agents, amphoteric surfactants, polymeric dispersants, and the like. Moreover, you may use these dispersing agents 1 type or in combination of 2 or more types.

  The conductive paste may contain an organic solvent other than that contained in the organic vehicle for viscosity adjustment.

(Conductive paste)
When the conductive paste is based on the viscosity after 24 hours of production of the conductive paste (0%), the viscosity after standing for one month from the reference date is preferably within ± 30%, more Preferably, it is within ± 25%.

Further, the density (DFD) of the dry film formed by printing the conductive paste is preferably more than 5.5 g / cm ³ , more preferably 5.6 g / cm ³ or more.

  The conductive paste can be suitably used for an electronic component such as a multilayer ceramic capacitor 1 as shown in FIG. The multilayer ceramic capacitor 1 includes a multilayer body 10 having a dielectric layer 12 formed using a dielectric green sheet and an internal electrode layer 11 formed using a conductive paste, and an external electrode 20. The electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of this embodiment is excellent in the printability of the conductive paste even when forming a thin electrode, and has a uniform width and thickness with high accuracy. Have

  In the multilayer ceramic capacitor 1, it is preferable that the dielectric ceramic powder contained in the dielectric green sheet and the ceramic powder contained in the conductive paste have the same composition. In the multilayer ceramic device manufactured using the conductive paste of the present embodiment, even when the thickness of the dielectric green sheet is, for example, 3 μm or less, sheet attack and green sheet peeling failure are suppressed.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited at all by the Example.

[Evaluation methods]
(Measurement of surface roughness of organic vehicle (dry film))
In the case of an organic vehicle containing an acetal resin and a cellulose resin, the compatibility between the two may be a problem. Therefore, the surface roughness Ra of the organic vehicle (dry film) is measured by the following method, The solubility was evaluated. If the compatibility is poor, each resin gathers and dries, and the dried film surface is not smooth. Therefore, it is considered that the smaller the surface roughness Ra of the organic vehicle (dried film), the better the compatibility of both.

  First, the organic vehicle was applied to a length of 10 cm with an applicator having a thickness of 200 μm, and then dried at 120 ° C. for 1 hour to obtain a dried organic vehicle film. Subsequently, the surface roughness Ra (arithmetic average roughness) of the produced dry film was measured based on the standard of JIS B0601-2001.

(Change in viscosity of conductive paste)
24 hours after manufacture, the viscosity of each sample was measured by the following method after 24 hours from the production of the conductive paste as a reference, and after standing at room temperature (25 ° C.) for 1 month from the reference time. When the viscosity after the passage was used as a reference (0%), the value of the change in the viscosity of the sample after standing as a percentage (%) was obtained ([viscosity after standing-after 24 hours of production). Viscosity after 24 hours of production] × 100). The viscosity of the conductive paste was measured using a Brookfield B-type viscometer under the condition of 10 rpm (shear rate = 4 sec ⁻¹ ). The smaller the amount of change in the viscosity of the conductive paste, the better.

(Dry film density)
The produced conductive paste was placed on a PET film and extended to a length of about 100 mm with an applicator having 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, and then this dried body was cut into 4 pieces of 2.54 cm (1 inch) squares, and the PET film was peeled off to remove 4 pieces each. The dry film density (average value) was calculated by measuring the thickness and weight of the dry film.

(Dry film surface roughness)
The produced conductive paste is screen-printed on a 2.54 cm (1 inch) square heat-resistant tempered glass and dried in the atmosphere at 120 ° C. for 1 hour to obtain a 20 mm square and a film thickness of 1 to 3 μm
A dry film was prepared. The surface roughness Ra (arithmetic mean roughness) of the produced dry film was measured based on the standard of JIS B0601-2001.

[Materials used]
(Conductive powder)
As the conductive powder, Ni powder (SEM average particle size 0.3 μm) was used.

(Ceramic powder)
As the ceramic powder, barium titanate (BaTiO ₃ ; SEM average particle size 0.06 μm) was used.

(resin)
As the resin, ethyl cellulose resin (EC resin) was used as the cellulose resin, and polyvinyl butyral resin (PVB resin) was used as the acetal resin.

(Dispersant) (1) As the amine-based dispersant, a dispersant represented by the following formula (1): R ₁ = C ₁₂ H ₂₅ , R ₃ = C ₂ H ₄ O, Y = 0, Z = 1 A1, In the above general formula (1), R ₁ = C ₁₂ H ₂₅ , R ₂ = C ₂ H ₄ O, R ₃ = C ₂ H ₄ O, Y = 1, Z = 1 dispersing agent A2, and, in the general formula _{(1), R 1 = C} 18 H 37, R 2 = C 2 H 4 O, R 3 = C 2 H 4 O, a dispersing agent A3 represented by Y = 1, Z = 1 Using.
(2) A base dispersant was used as a dispersant other than amine.

(Organic solvent)
Turpineol was used as the organic solvent.

[Comparative Examples 1 and 2]
In Comparative Example 1, the first mixture (PVB vehicle) and the second mixture (EC vehicle) prepared at the ratio shown in Table 1 were mixed, and only stirred for 5 hours to prepare an organic vehicle at 25 ° C. did. Table 1 shows the evaluation results of the surface roughness Ra of the obtained organic vehicle. In addition, the 1st mixture and the 2nd mixture were produced by mixing each resin and the organic solvent, heating in the range of 40 degreeC or more and 120 degrees C or less. The mass% in Table 1 indicates the content ratio (mixing ratio) of each material when the total amount of the organic vehicle (third mixture) is 100 mass%.

  Thereafter, an organic vehicle in the proportion (mass%) shown in Table 2, Ni powder 50 mass%, ceramic powder 3.8 mass% dispersed in terpineol 6.3 mass%, and other dispersants As the organic solvent for viscosity adjustment, 12.7% by mass of mineral spirit and terpineol were added as an organic solvent for viscosity adjustment, and these materials were mixed to prepare a conductive paste. Table 2 shows the mixing ratio of the main materials of the conductive paste and the evaluation results. In addition, the said terpineol (for viscosity adjustment) was added as remainder so that the whole quantity of an electrically conductive paste might be 100 mass%.

  In Comparative Example 2, the first mixture (PVB vehicle), the second mixture (EC vehicle), and the amine-based dispersant were mixed at the ratio shown in Table 1, and only stirred at 25 ° C. for 5 hours. A conductive paste was produced under the same conditions as in Comparative Example 1 except that the vehicle was produced.

  In Comparative Example 3, the first mixture (PVB vehicle), the second mixture (EC vehicle), and the amine-based dispersant were mixed at the ratio shown in Table 1, and only stirred at 25 ° C. for 5 hours. A conductive paste was produced under the same conditions as in Comparative Example 1 except that a vehicle was produced.

[Comparative Examples 4, 5, 6]
In Comparative Examples 4 and 5, the first mixture (PVB vehicle), the second mixture (EC vehicle), and the amine-based dispersant were mixed at the ratio shown in Table 1, and stirred at 65 ° C. for 5 hours. A conductive paste was produced under the same conditions as in Comparative Example 1 except that an organic vehicle was produced. Table 1 shows the evaluation results of the organic vehicle.

[Examples 1 to 10]
A mixed vehicle (organic vehicle) was prepared in the same manner as in Comparative Example 4 except that the amounts and conditions shown in Table 1 were changed, and then a conductive paste was prepared under the same conditions as in Comparative Example 4. The evaluation results of the organic vehicle are shown in Table 1, and the evaluation results of the conductive paste are shown in Table 2.
[Example 11]
The same amount of PVB resin, EC resin, amine dispersant as used in Example 2 and the total amount of organic solvent were mixed once (simultaneously) and stirred at 65 ° C. for 5 hours. A conductive paste was produced under the same conditions as in Comparative Example 4 except that an organic vehicle was produced. Table 1 shows the ratio of each material. The amount of the organic solvent used was described in the item of the organic solvent of the first mixture for convenience. The evaluation results of the organic vehicle are shown in Table 1, and the evaluation results of the conductive paste are shown in Table 2.

[Evaluation results]
It was shown that the surface roughness Ra of the organic vehicle obtained in the examples was lower than that of the organic vehicle obtained in Comparative Examples 1 to 5, and the compatibility of the resin was improved. Moreover, when compared with the conductive pastes obtained in Comparative Examples 1 to 5, the conductive pastes obtained in the examples have an improved dry film density and reduced changes in the viscosity of the conductive paste over time. Was shown to be. Moreover, in the conductive paste of Comparative Example 6 containing the amine-based dispersant in a proportion exceeding 440 mass with respect to the PVB resin, the paste viscosity immediately after the production was too low, and it was difficult to print (apply). .

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 10 Laminated body 11 Internal electrode layer 12 Dielectric layer 20 External electrode 21 External electrode layer 22 Plating layer

Claims (10)

Mixing an acetal resin, a cellulose resin, an amine dispersant, and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower,
The method for producing an organic vehicle, wherein the amine dispersant is mixed in an amount of 9 to 440 parts by mass with respect to 100 parts by mass of the acetal resin. Mixing an acetal resin and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a first mixture;
Mixing a cellulose resin and an organic solvent at a temperature of 40 ° C. or higher and 120 ° C. or lower to obtain a second mixture;
Mixing the first mixture, the second mixture, and the amine-based dispersant at a temperature of 40 ° C. or more and 120 ° C. or less,
The method for producing an organic vehicle, wherein the amine dispersant is mixed in an amount of 9 to 440 parts by mass with respect to 100 parts by mass of the acetal resin. The method for producing an organic vehicle according to claim 1 or 2, wherein the amine-based dispersant has a structure represented by the following general formula (1).

(Wherein (1), _{R 1} represents an alkyl group having 8 to 16 carbon atoms, an alkenyl group, or an alkynyl group, _{R 2} represents an oxyethylene group, oxypropylene group, or a methylene radical, R ₃ represents an oxyethylene group or an oxypropylene group, and R ₂ and R ₃ may be the same or different, and the N atom in formula (1) and R ₂ and R ₃ (It is not directly bonded to the O atom, Y is a number from 0 to 2, and Z is a number from 1 to 2.)   The organic vehicle according to any one of claims 1 to 3, wherein the organic solvent has a boiling point of 100 ° C or higher and 300 ° C or lower and is soluble in both the acetal resin and the cellulose resin. Method. Obtaining an organic vehicle by the method of any one of claims 1-4;
A method for producing a conductive paste, comprising: mixing a conductive powder, a ceramic powder, and the organic vehicle.   The said amine type dispersing agent is a manufacturing method of the electrically conductive paste of Claim 5 contained 0.11 to 5.5 mass% with respect to 100 mass% of electrically conductive paste.   The method for producing a conductive paste according to claim 5 or 6, wherein the conductive powder is at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. .   The manufacturing method of the electrically conductive paste of any one of Claims 5-7 whose average particle diameters of the said electrically conductive powder are 0.05 micrometer or more and 1.0 micrometer or less.   The method for producing a conductive paste according to any one of claims 5 to 8, wherein the ceramic powder is a perovskite oxide.   The manufacturing method of the electrically conductive paste of any one of Claims 5-9 whose average particle diameters of the said ceramic powder are 0.01 micrometer or more and 0.5 micrometer or less.

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