JP7119454B2 - Method for producing organic vehicle and method for producing conductive paste - Google Patents

Description

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

BACKGROUND ART As electronic devices such as mobile phones and digital devices have become smaller and have higher performance, electronic components including laminated ceramic capacitors have also been desired to be smaller and have higher capacity. Multilayer ceramic capacitors have a structure in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated. By thinning these dielectric layers and internal electrode layers, miniaturization and high capacity can be achieved. can be planned.

A laminated ceramic capacitor is manufactured, for example, as follows. First, on the surface of a dielectric green sheet containing a dielectric powder such as barium titanate (BaTiO ₃ ) and a binder resin, a conductive paste for internal electrodes is printed (applied) in a predetermined electrode pattern and dried. to form a dry film. Next, dry films and green sheets are alternately laminated to obtain a laminate. Next, this laminated body is thermocompression-bonded to be integrated to form a compression-bonded body. This pressed body is cut, treated to remove the organic binder in an oxidizing atmosphere or an inert atmosphere, and then fired to obtain fired chips. Next, an external electrode paste is applied to both ends of the sintered chip, and after sintering, nickel plating or the like is applied to the surfaces of the external electrodes to obtain a multilayer ceramic capacitor.

Generally, the conductive paste used for forming internal electrode layers contains conductive powder, ceramic powder, binder resin and organic solvent. Also, the conductive paste may contain a dispersant to improve the dispersibility of the conductive powder. With the thinning of internal electrode layers in recent years, there is a tendency for the conductive powder to have a smaller particle size as well. When the particle size of the conductive powder is small, the specific surface area of the particle surface increases, so the surface activity of the conductive powder (metallic powder) increases, making it easier for aggregation to occur, resulting in a decrease in dispersibility and viscosity. Degradation of properties may occur.

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

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

WO2017/014295

However, in the method described in Patent Document 1, the process of producing the reactive resin is complicated and requires a long process, which causes an increase in cost. Therefore, a more convenient production method has been desired.

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

A first aspect of the present invention comprises mixing an acetal-based resin, a cellulose-based resin, an amine-based dispersant, and an organic solvent at a temperature of 40° C. or higher and 120° C. or lower, wherein the amine-based dispersant is acetal. Provided is a method for producing an organic vehicle, in which 9 parts by mass or more and 440 parts by mass or less is mixed with 100 parts by mass of the system resin.

In a second aspect of the present invention, the acetal-based 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, and the cellulose-based resin and the organic solvent are heated to 40° C. or higher and 120° C. or higher. obtaining a second mixture by mixing at a temperature of ℃ or less; and mixing the first mixture, the second mixture, and an amine-based dispersant at a temperature of 40 to 120 °C. , an amine-based 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-based 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。） Further, in the method for producing an organic vehicle, the amine-based dispersant preferably has a structure represented by the following general formula (1).

(In formula (1), R ₁ represents an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms, R ₂ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₃ represents an oxyethylene group or an oxypropylene group, 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.)

Moreover, the organic solvent preferably has a boiling point of 100° C. or higher and 300° C. or lower and has solubility in both the acetal-based resin and the cellulose-based 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 above, mixing a conductive powder, a ceramic powder, and the organic vehicle; A method for producing a conductive paste is provided.

Moreover, it is preferable that 0.11% by mass or more and 5.5% by mass or less of the amine-based dispersant is contained with respect to 100% by mass of the conductive paste. Also, the conductive powder is preferably at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. Also, the average particle size of the conductive powder is preferably 0.05 μm or more and 1.0 μm or less. Also, the ceramic powder is preferably a perovskite oxide. Also, the average particle size of the ceramic powder is preferably 0.01 μm or more and 0.5 μm 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. In addition, the organic vehicle of the present invention has excellent compatibility with resins and can be suitably used for the conductive paste.

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

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the drawings, in order to make each configuration easy to understand, some parts are emphasized or some parts are simplified, and the actual configuration, shape, scale, etc. may differ. In addition, the present invention is not limited to the following embodiments. Also, various modifications and replacements can be made to the following embodiments without departing from the scope of the present invention.

1. Organic Vehicle Production Method (1) First Embodiment [Mixing Step (Step S10)]
FIG. 1 is a diagram showing an example of a method for producing an organic vehicle according to this embodiment. In the method for producing an organic vehicle according to the present embodiment, as shown in FIG. 1, an acetal-based resin, a cellulose-based resin, an amine-based dispersant, and an organic solvent are mixed at a temperature of 40° C. or higher and 120° C. or lower ( step S10).

The conductive paste produced using the organic vehicle obtained in the mixing step (step S10) improves the dispersibility and viscosity stability of the conductive paste, although the details are unknown. Further, in a conductive paste containing an acetal-based resin and a cellulose-based resin, the compatibility of these resins may be a problem. improves. Each material will be described below.

(Cellulose resin)
The cellulose resin is not particularly limited, and known cellulose resins (cellulose derivatives) used as binder resins in conductive pastes can be used. Cellulose-based resins include, for example, ethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, methyl cellulose, propyl cellulose, acetyl cellulose and the like. Among them, it is preferable to include ethyl cellulose resin (hereinafter also referred to as "EC resin") from the viewpoint of solubility in solvents, combustion decomposability, and the like. In addition, one type may be used for cellulose resin, and two or more types may be used for it.

(acetal resin)
The acetal-based resin is not particularly limited, and known acetal-based resins used as binder resins can be used. Examples of acetal-based resins include polyvinyl butyral resin (hereinafter also referred to as “PBV resin”). When an acetal-based resin is used, the adhesiveness between the conductive paste (internal electrode) and the dielectric green sheet can be improved. One type of acetal-based resin may be used, or two or more types may be used.

In addition, in the mixing step (step S10), a resin other than the cellulose-based resin and the acetal-based resin (for example, an acrylic resin, etc.) may be used as long as the effects of the present invention are not impaired.

(Amine dispersant)
The inventors of the present invention have investigated various additives for use in the conductive paste. It has been found that the viscosity change is small, the Ni powder is excellent in dispersibility, and the dry film density after coating is excellent. The dispersant used in this embodiment will be described below.

The amine-based dispersant is not particularly limited, and a known amine-based dispersant used as a dispersant in conductive pastes can be used. The amine-based dispersant is preferably, for example, an amine-based dispersant represented by the following general formula (1). One type of amine-based 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。）

(In formula (1) above, R ₁ represents an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms; R ₂ represents an oxyethylene group, an oxypropylene group, or a methylene group; R ₃ represents an oxyethylene group or an oxypropylene group, R ₂ and R ₃ may be the same or different, and the N atom in formula (1), R ₂ and R 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 represented by the above general formula (1), and has a structure in which an amine group and one or two oxyethylene groups are bonded. It is preferred to have

In formula (1) above, R ₁ represents an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms. When the carbon number of R ₁ is within the above range, the powder in the resulting conductive paste has sufficient dispersibility and excellent solubility in solvents. 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 or may not be the same. Further, the N atom in formula (1) and the O atom in R ₂ and R ₃ are not directly bonded, Y is a number of 0 or more and 2 or less, and Z is a number of 1 or more and 2 or less.

For example, when R ₂ is an oxyalkylene group represented by —(AO) _Y —, the O atom in the oxyalkylene group bonds to the H atom adjacent to R ₂ . In addition, when R ₂ is a methylene group, R ₂ is represented by -(CH ₂ ) _Y -, and when Y is 1 to 2, it is a methyl group (-CH ₃ ) or an ethyl group together with the adjacent H element. A group (--CH ₂ --CH ₃ ) is formed. Also, when R ₃ is an oxyalkylene group represented by —(AO) _z —, an O atom in the oxyalkylene group bonds to an H atom adjacent to R ₃ .

In the above formula (1), when Y is 0, the amine 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-based dispersant contains an alkyl group, an alkenyl group, or an alkynyl group having 8 to 16 carbon atoms, one hydrogen group, and one polyoxyethylene group. Alternatively, it becomes a secondary amine composed of a polyoxypropylene group.

Further, when Y is 1 in the formula (1), the amine-based 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-based dispersant is a tertiary amine having an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms, and at least one polyoxyethylene group or polyoxypropylene group. becomes.

As the amine-based additive represented by the above formula (1), for example, one that satisfies the above characteristics can be selected from commercially available products and used. In addition, the amine-based additive may be produced using a conventionally known production method so as to satisfy the above structure.

(Organic solvent)
The organic solvent is not particularly limited, and any known organic solvent capable of dissolving the binder resin can be used. Examples of organic solvents include dihydroterpinyl acetate, isobornyl acetate, isobornyl propinate, isobornyl butyrate and isobornyl isobutyrate, ethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, and the like. , terpene solvents such as terpineol and dihydroterpineol, and hydrocarbon solvents such as tridecane, nonane and cyclohexane. One type of organic solvent may be used, or two or more types may be used.

The boiling point of the organic solvent is preferably 100° C. or higher and 300° C. or lower, more preferably 120° C. or higher and 260° C. or lower.

(Mixing ratio)
The mixing ratio of each material is explained below. In addition, the mixing ratio with respect to the whole mixture obtained by mixing each material below corresponds to the content ratio of each material (raw material) with respect to the whole organic vehicle obtained.

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

The mixing ratio of the acetal-based resin (eg, PVB resin) and the cellulose-based 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-based resin, and is 55 parts by weight. Part or more and 90 parts by weight or less is more preferable. If the ratio exceeds 100 parts by weight, the printability may deteriorate and the dry film density may not be improved. If the content is less than 50 parts by weight, the adhesion to the green sheet may deteriorate during the MLCC process, making it difficult to produce the laminate.

Further, 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. It is more preferably 40 parts by mass or more and 400 parts by mass or less. When the amine-based dispersant is contained within the above range, the compatibility between the acetal-based resin and the cellulose-based resin is improved. In addition, when the amine-based dispersant is contained in the above range, it is possible to suppress changes in viscosity over time when used in a conductive paste, improve viscosity stability, and have a high dry film density. 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, relative to the entire mixture (total amount) obtained by mixing each material. %, preferably 0.5% by mass or more and 15% by mass or less, more preferably 0.8% by mass or more and 8% by mass or less. When the amine-based dispersant is contained within the above range, the compatibility between the acetal-based resin and the cellulose-based resin is improved. Moreover, when used in a conductive paste, it is possible to suppress changes in viscosity over time, improve viscosity stability, and have a high dry film density.

Further, 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, preferably 10.75 parts by mass or more and 300 parts by mass with respect to 100 parts by mass of the total mixed amount of the cellulose resin. parts or less, more preferably 28 parts by mass or more and 285 parts by mass or less.

Further, the mixing ratio of the amine-based 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 mixed amount of the acetal-based resin and the cellulose-based resin. parts or more and 175 parts by mass or less, more preferably 16.5 parts by mass or more and 165 parts by mass or less.

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

The mixing ratio of the organic solvent is preferably 40% by mass or more and 95% by mass or less, 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. be. When the content of the organic solvent is within the above range, the electroconductivity and dispersibility are excellent.

(mixing temperature)
In the mixing step (step S10), the above 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. If the temperature is less than 40°C, the effects of the present invention cannot be obtained. On the other hand, if the temperature exceeds 120° C., the organic solvent may volatilize or deteriorate due to oxidation, which is not preferable. Moreover, the temperature is preferably lower than the boiling point of the organic solvent used in this embodiment.

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

Moreover, as a mixing method, for example, stirring can be performed using a motor with rotating blades that operates electrically or by air. The stirring speed is not particularly limited, but is, for example, about 50 rpm to 150 rpm. Other mixing conditions are not particularly limited, and ordinary mixing conditions can be used.

(2) Second Embodiment FIG. 2 is a diagram showing another example of the method for producing an organic vehicle according to this embodiment. Another method for producing an organic vehicle according to the present embodiment is, as shown in FIG. 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-based dispersant at a temperature of 40° C. or higher and 120° C. or lower (third mixing step: step S10). Each step will be described below.

[First Mixing Step (Step S1)]
In the first mixing step (Step S1), 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. Preferred types of the acetal-based resin and the organic solvent are the same as those in the above-described first embodiment, so descriptions thereof are omitted.

The mixing ratio of the acetal-based resin and the organic solvent is not particularly limited as long as the acetal-based resin is sufficiently dissolved in the organic solvent. Mix at mass % or less.

Moreover, the temperature at which the acetal-based resin and the organic solvent are mixed is 40° C. or higher and 120° C. or lower.

[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. 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). Preferred types of cellulose-based resin and organic solvent are the same as in the above-described first embodiment, so descriptions thereof are omitted. The type of organic solvent may be the same as or different from the organic solvent used in the first mixing step.

The mixing ratio of the cellulose resin and the organic solvent is not particularly limited as long as the cellulose resin is sufficiently dissolved in the organic solvent. Mix at mass % or less.

Moreover, the temperature at which the cellulose-based resin and the organic solvent are mixed is 40° C. or higher and 120° C. or lower.

[Third Mixing Step (Step S10)]
Next, the first mixture, the second mixture, and the amine-based 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 components are heated and mixed in each organic solvent in advance, each material can be mixed more uniformly in the third mixing step (step S10).

The mixing ratio of the first mixture, the second mixture, and the amine-based dispersant is the same range as the mixing ratio with respect to the entire mixture obtained by mixing each material in the above-described first embodiment. The description is omitted because it is sufficient to mix so that the In addition, the mixing ratio with respect to the whole mixture obtained by mixing each material below corresponds to the content ratio of each material (raw material) with respect to the whole organic vehicle obtained.

Also, the mixing conditions are the same as in the above-described first embodiment, so the description is omitted.

2. Method for Producing Conductive Paste FIG. 3 is a diagram showing an example of a method for producing a conductive paste according to this embodiment. As described above, the method for producing a conductive paste of the present embodiment includes the step of obtaining an organic vehicle in the mixing step (step S10), and the step of mixing the conductive powder, the ceramic powder, and the obtained organic vehicle ( step S20); The resulting conductive paste contains conductive powder, ceramic powder, dispersant, binder resin and organic solvent. The organic vehicle can be obtained by a method including at least a mixing step (step S10), may be obtained by the production method of the first embodiment described above, or may be obtained by the production method of the second embodiment. You may get Each material used for the conductive paste and the resulting conductive paste will be described below.

(Conductive powder)
The conductive powder is not particularly limited, and metal powder can be used. For example, one or more powders selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof can be used. Among these, powder of Ni or its alloy 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 can be used. can. The content of Ni in the Ni alloy is, for example, 50% by mass or more, preferably 80% by mass or more. In addition, the Ni powder may contain about several hundred ppm of S in order to suppress sudden gas generation due to partial thermal decomposition of the binder resin during binder removal treatment.

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

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 60% by mass or less, relative to the total amount of the conductive paste. When the content of the conductive powder is within the above range, the conductivity and dispersibility are excellent.

(ceramic powder)
The ceramic powder is not particularly limited. For example, in the case of a paste for internal electrodes of a laminated ceramic capacitor, a known ceramic powder is appropriately selected depending on the type of laminated ceramic capacitor to be applied. Ceramic powders include, for example, perovskite-type oxides containing Ba and Ti, preferably barium titanate (BaTiO ₃ ).

As the ceramic powder, a ceramic powder containing barium titanate as a main component and an oxide as an auxiliary component may be used. The oxides 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, there is a perovskite-type oxide ferroelectric ceramic powder in which Ba atoms or Ti atoms of barium titanate (BaTiO ₃ ) are replaced with other atoms such as Sn, Pb, Zr, or the like. mentioned.

In the conductive paste for internal electrodes, a powder having the same composition as the dielectric ceramic powder that constitutes the green sheets of the multilayer ceramic capacitor may be used. As a result, the occurrence of cracks due to shrinkage mismatch at the interfaces between the dielectric layers and the internal electrode layers in the sintering process is suppressed. Examples of such ceramic powder include, in addition to the above, ZnO, ferrite, PZT, BaO, Al ₂ O ₃ , Bi ₂ O ₃ , R (rare earth element) ₂ O ₃ , TiO ₂ , Nd ₂ O ₃ and the like. oxides. One type of ceramic powder may be used, or two or more types may be used.

The average particle size 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. Since the average particle size of the ceramic powder is within the above range, when it is used as an internal electrode paste, sufficiently fine and thin uniform internal electrodes can be formed. The average particle size is a value obtained from observation with a scanning electron microscope (SEM), and is obtained by measuring the particle size of each of a plurality of particles from an image observed with a SEM at a magnification of 50,000. is the average value obtained.

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 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, more preferably 5% by mass or more and 20% by mass or less, relative to the total amount of the conductive paste. When the content of the conductive powder is within the above range, the conductivity and dispersibility are excellent.

(organic vehicle)
The organic vehicle is obtained by the mixing step (step S10) as described above. Organic vehicles include acetal resins, cellulose resins, amine dispersants, and organic solvents. The content of the entire 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, relative to the total amount of the conductive paste. .

The content of the amine-based dispersant is preferably 0.11% by mass or more and 5.50% by mass or less, and more preferably 0.19% by mass or more, based on the total amount of the conductive paste (100% by mass). It is 25% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less.

(other materials)
The conductive paste may include, for example, acid-based dispersants containing higher fatty acids and polymer surfactants, cationic dispersants other than acid-based dispersants, and nonionic dispersants, as long as the effects of the present invention are not impaired. agents, amphoteric surfactants, polymeric dispersants, and the like. These dispersants may be used singly or in combination of two or more.

Also, the conductive paste may contain an organic solvent other than the above organic vehicle for viscosity adjustment.

(Conductive paste)
The conductive paste has a viscosity after standing for one month from the reference date, preferably within ±30%, when the viscosity after 24 hours of production of the conductive paste is taken as the reference (0%). It is preferably within ±25%.

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

The conductive paste can be suitably used for electronic components such as a laminated ceramic capacitor 1 as shown in FIG. A multilayer ceramic capacitor 1 includes a laminate 10 having dielectric layers 12 formed using dielectric green sheets and internal electrode layers 11 formed using a conductive paste, and external electrodes 20 . The electrode pattern of an electronic component such as a multilayer ceramic capacitor formed using the conductive paste of the present embodiment has excellent printability of the conductive paste even when forming a thinned electrode, and has a uniform width and thickness with high accuracy. have

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

EXAMPLES The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited by the examples.

[Evaluation method]
(Measurement of surface roughness of organic vehicle (dry film))
In the case of an organic vehicle containing an acetal-based resin and a cellulose-based resin, compatibility between the two may become a problem. Solubility was evaluated. If the compatibility is poor, the resins will dry together and the surface of the dry film will not be smooth.

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

(Amount of change in viscosity of conductive paste)
The viscosity of each sample was measured by the following method at the reference point after 24 hours from the production of the conductive paste and after standing at room temperature (25 ° C.) for one month from the reference point, and 24 hours after production. The amount of change in the viscosity of the sample after standing was expressed as a percentage (%) when the viscosity after standing was taken as the reference (0%) ([viscosity after standing - after 24 hours of production viscosity)/viscosity after 24 hours of production]×100). The viscosity of the conductive paste was measured using a Brookfield viscometer at 10 rpm (shear rate=4 sec ⁻¹ ). In addition, it is preferable that the amount of change in the viscosity of the conductive paste is as small as possible.

(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 squares of 2.54 cm (1 inch), and the PET film was peeled off. The thickness and weight of each sheet of dry film were measured to calculate the dry film density (average value).

(Surface roughness of dry film)
The prepared conductive paste was 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, resulting in a 20 mm square and a film thickness of 1 to 3 μm.
was prepared. The surface roughness Ra (arithmetic mean roughness) of the produced dry film was measured according to the standard of JIS B0601-2001.

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

(ceramic powder)
Barium titanate (BaTiO ₃ ; SEM average particle size 0.06 μm) was used as the ceramic powder.

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

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

(Organic solvent)
Terpineol 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 ratios 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. The first mixture and the second mixture were prepared by mixing the respective resins and the organic solvent while heating them in the range of 40° C. or higher and 120° C. or lower. 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 %.

After that, an organic vehicle having a ratio (% by mass) shown in Table 2, 50% by mass of Ni powder, 6.3% by mass of co-material slurry in which 3.8% by mass of ceramic powder is dispersed in terpineol, and other dispersants 0.4% by mass of a basic dispersant as a component, and 12.7% by mass of mineral spirit and terpineol as an organic solvent for viscosity adjustment were added, 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. The terpineol (for viscosity adjustment) was added as the balance so that the total amount of the conductive paste was 100% by mass.

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

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

[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 ratios shown in Table 1, and the mixture was stirred at 65°C for 5 hours. A conductive paste was prepared under the same conditions as in Comparative Example 1, except that an organic vehicle was prepared. 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. Table 1 shows the evaluation results of the organic vehicle, and Table 2 shows the evaluation results of the conductive paste.
[Example 11]
The same amounts of PVB resin, EC resin, and amine-based 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 prepared under the same conditions as in Comparative Example 4, except that an organic vehicle was prepared. Table 1 shows the ratio of each material. The amount of the organic solvent used is described in the item of the organic solvent of the first mixture for convenience. Table 1 shows the evaluation results of the organic vehicle, and Table 2 shows the evaluation results of the conductive paste.

[Evaluation results]
The surface roughness Ra of the organic vehicles obtained in Examples was lower than those of the organic vehicles obtained in Comparative Examples 1 to 5, indicating that the resin compatibility was improved. In addition, the conductive pastes obtained in Examples have an improved dry film density and a reduced viscosity change over time compared to the conductive pastes obtained in Comparative Examples 1 to 5. was shown to be Moreover, in the conductive paste of Comparative Example 6, which contained an amine-based dispersant in a proportion exceeding 440 mass relative to the PVB resin, the paste viscosity immediately after preparation was too low, making printing (coating) difficult. .

1 multilayer ceramic capacitor 10 laminate 11 internal electrode layer 12 dielectric layer 20 external electrode 21 external electrode layer 22 plating layer

Claims (9)

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 amine-based dispersant has a structure represented by the following general formula (1) ,
A method for producing an organic vehicle, wherein the amine-based 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 the acetal-based resin.

(In formula (1), R ₁ represents an alkyl group, alkenyl group, or alkynyl group having 8 to 16 carbon atoms, R ₂ represents an oxyethylene group, an oxypropylene group, or a methylene group, and R ₃ represents an oxyethylene group or an oxypropylene group, 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.) obtaining a first mixture by mixing an acetal-based resin and an organic solvent at a temperature of 40° C. or higher and 120° C. or lower;
Obtaining a second mixture by mixing a cellulose resin and an organic solvent at a temperature of 40° C. or higher and 120° C. or lower;
mixing the first mixture, the second mixture, and an amine-based dispersant at a temperature of 40° C. or higher and 120° C. or lower;
A method for producing an organic vehicle, wherein the amine-based 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 the acetal-based resin. 3. The method for producing an organic vehicle according to claim 1, wherein the organic solvent has a boiling point of 100[deg.] C. or higher and 300[deg.] C. or lower, and is soluble in both the acetal-based resin and the cellulose-based resin. Obtaining an organic vehicle by the method according to any one of claims 1 to 3 ;
A method for producing a conductive paste, comprising mixing a conductive powder, a ceramic powder, and the organic vehicle. 5. The method for producing a conductive paste according to claim 4 , wherein the amine-based dispersant is contained in an amount of 0.11% by mass or more and 5.5% by mass or less with respect to 100% by mass of the conductive paste. The method for producing a conductive paste according to claim 4 or 5 , wherein the conductive powder is at least one metal powder selected from Ni, Pd, Pt, Au, Ag, Cu, and alloys thereof. . The method for producing a conductive paste according to any one of claims 4 to 6 , wherein the conductive powder has an average particle size of 0.05 µm or more and 1.0 µm or less. The method for producing a conductive paste according to any one of claims 4 to 7 , wherein the ceramic powder is a perovskite oxide. The method for producing a conductive paste according to any one of claims 4 to 8 , wherein the ceramic powder has an average particle size of 0.01 µm or more and 0.5 µm or less.

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