JP6179274B2 - Nickel paste manufacturing method and nickel paste - Google Patents

Description

  The present invention relates to a method for producing a nickel paste for internal electrodes of a multilayer ceramic capacitor and a nickel paste.

  Generally, a nickel paste used for an internal electrode of a multilayer ceramic capacitor (hereinafter also referred to as MLCC) is manufactured by kneading nickel powder in a vehicle, and contains a large number of nickel powder aggregates. In other words, the final stage of the nickel powder production process usually has a drying process regardless of the metal powder production method (dry method, wet method), and this drying process promotes the aggregation of nickel particles. Nickel powder generally contains aggregates produced during drying.

  Recent multilayer ceramic capacitors are required to increase the number of laminated ceramic green sheets with internal electrode layers from several hundred to about 1000 in order to achieve a small size and large capacity. For this reason, studies have been made to reduce the thickness of the internal electrode layer from the conventional level of about 3 μm to the submicron level, and accordingly, the particle size of the metal powder is being reduced.

  However, the smaller the particle size, the larger the surface area of the powder, the greater the surface energy, and the easier it is to form aggregates. Also, if the dispersibility of the metal ultrafine powder is poor and aggregates are present, the ceramic sheet layer will be penetrated, resulting in a defective product in which the electrodes are short-circuited, and even if not penetrated, the distance between the electrodes will be reduced. As a result, partial current concentration occurs, which causes the life of the multilayer ceramic capacitor to deteriorate.

  As a nickel ultrafine powder slurry used for an internal electrode of MLCC, a slurry described in Patent Document 1 is disclosed. In Patent Document 1, first, a metal ultrafine powder water slurry (metal ultrafine powder concentration: 50 mass%) added with 0.3 part by mass of a specific anionic surfactant with respect to 100 parts by mass of metal ultrafine powder. Then, after carrying out a dispersion treatment using a process homogenizer for a predetermined time to disperse aggregates of ultrafine metal powder in water to primary particles, for example, terpineol is used as an organic solvent with respect to 100 parts by mass of ultrafine metal powder. It is described that 10 parts by mass is added.

JP 2006-63441 A

Ueda et al. Chemistry and Education, Vol. 40, no. 2, (1992) p114-117

  However, in the manufacturing method of Patent Document 1, since a specific anionic surfactant is added directly to the metal ultrafine powder water slurry, the surfactant becomes micelle, making it difficult to adsorb on the surface of the metal powder. There was a problem that it was not right. The present invention provides a nickel paste that disperses nickel powder in a more agglomerate-free state than Patent Document 1 and is excellent in dry film density after coating, and is suitably used for internal electrodes of multilayer ceramic capacitors. For the purpose.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by adding a specific type and amount of surfactant together with an organic solvent to an aqueous slurry of nickel powder. The inventor has completed the present invention. Specifically, the present invention provides the following.

[1] A nickel organic slurry forming step of adding an organic solvent and a surfactant to an aqueous slurry of nickel powder;
A water separation step of separating the water layer from the nickel organic slurry separated into an aqueous layer and an organic layer to obtain an organic layer nickel organic slurry;
A step of adding an organic resin binder to the organic layer nickel organic slurry and kneading, and a method for producing a nickel paste,
In the nickel organic slurry forming step, the surfactant contains a dispersion transfer accelerator represented by the following general formula (1) or (2),
The amount of the dispersion transfer accelerator added to the nickel powder is an amount such that the total molecular cross-sectional area of the dispersion transfer accelerator is 1 to 4 times the total surface area of the nickel powder.
S ₁ / W, which is a ratio of the mass S _{1 of the} organic solvent and the mass W of water in the water slurry of the nickel powder, is in the range of 0.02 <S ₁ /W<0.4. A method for producing a nickel paste characterized by the above.
(In general formula (1) or (2), n is an integer of 10 to 20)

[2] The dispersion transfer accelerator is at least one selected from the group consisting of lauroyl sarcosine, lauroylmethyl-β-alanine, myristoylmethyl-β-alanine, cocoyl sarcosineate, myristoyl sarcosinate, palmitoyl sarcosine, stearoyl sarcosine. The method for producing a nickel paste according to [1] .

[3] The amount of the dispersion transition accelerator comprising nickel powder having a surface coated with the dispersion transition accelerator represented by the general formula (1) or (2), an organic solvent, and an organic resin binder. Is 0.00100 g / m ² or more and 0.00900 g / m ² or less with respect to 1 m ² of the surface of the nickel powder, and has a moisture content of less than 1% by mass by the Karl Fischer method.

  ADVANTAGE OF THE INVENTION According to this invention, nickel powder can be disperse | distributed in the state without an aggregate, it is excellent in the dry film density after application | coating, and the nickel paste used suitably for the internal electrode of a multilayer ceramic capacitor can be provided.

  In addition, since the nickel paste of the present invention does not include a drying step in the paste mass production process, it can suppress the oxidation of the powder, so that a paste having no dry aggregation and stable in quality can be obtained, and at the same time, it is a harmful substance. Since some nickel dust is not generated, it is excellent from the viewpoint of health and safety.

The nickel paste manufacturing method of the present invention includes the following three steps (A) to (C).
(A) A nickel organic slurry forming step of adding an organic solvent and a surfactant to an aqueous slurry of nickel powder.
(B) The water separation process which isolate | separates the said water layer from the said nickel organic slurry isolate | separated into the water layer and the organic layer, and obtains organic layer nickel organic slurry.
(C) A kneading step in which an organic resin binder is added to the organic layer nickel organic slurry and kneaded.
Hereinafter, each step will be described.

<(A) Nickel organic slurry forming step>
In the step (A), an organic solvent and a surfactant are added to an aqueous slurry of nickel powder (nickel powder water slurry).

(Nickel powder water slurry)
Nickel powder can be used regardless of the manufacturing method of nickel powder, such as a wet method and a dry method, and is not specifically limited. Specifically, the nickel powder is a so-called wet method such as a wet reduction method using a nickel salt solution such as hydrazine even in a so-called dry method such as a CVD method, an evaporation quenching method, or a hydrogen reduction method such as nickel salt or nickel hydroxide. Nickel powder of the method may be used, and the manufacturing method is not limited. It is preferable to have an average particle size of 0.05 μm to 0.5 μm, which is suitable for use as a multilayer ceramic capacitor internal electrode. This nickel is dispersed in water by a conventionally known method to obtain a nickel powder water slurry.

  The nickel content is preferably 20% by mass or more and 75% by mass or less. If the amount is less than 20% by mass, the amount of water is too large, and a large amount of an organic solvent is used to obtain a nickel organic slurry. Since the nickel concentration is low, it is difficult to obtain a good nickel paste. If it exceeds 50%, the amount of water is small, and separation from the organic solvent is insufficient, and moisture tends to remain.

(Surfactant)
In the present invention, a dispersion transfer accelerator which is an anionic surfactant having the following specific structure is used as the surfactant. Here, if the n number is less than 10, the hydrophilicity is strong and water is difficult to escape. When n number is larger than 20, it becomes oleophilic and water can be easily removed, but it is difficult to dissolve in an organic solvent and the surface cannot be efficiently coated.
(In general formula (1) or (2), n is an integer of 10 to 20)

Specifically, the structural formula when n = 10 in the general formula (1) is shown as the following structural formula (1-1). The dispersion transfer accelerator represented by the structural formula (1-1) is commercially available with a chemical name of “lauroyl sarcosine” (molecular formula = C ₁₅ H ₂₉ NO ₃ , CAS No. = 97-78-9). It is a surfactant.

Other dispersion transfer accelerators that can be used in the present invention include chemical names “lauroylmethyl-β-alanine (structural formula (2-1) below, molecular formula = C ₁₆ H ₃₁ NO ₃ , CAS No. 21539-57-1, ), Chemical name “myristoylmethyl-β-alanine (structural formula (2-2) below, molecular formula = C ₁₈ H ₃₅ NO ₃ , CAS No. 21539-71-9), etc., and cocoyl sarcosinate (general Formula (1), molecular formula = C ₁₆ H ₃₁ NO ₃ ), myristoyl sarcosinate (general formula (1), molecular formula = C ₁₇ H ₃₃ NO ₃ ), palmitoyl sarcosine (general formula (1), molecular formula = C ₁₉ H ₃₇ NO ₃ ) and stearoyl sarcosine (general formula (1), molecular formula = C ₂₁ H ₄₁ NO ₃ ).

(Organic solvent)
The organic solvent is a solvent that is usually used as a solvent for conductive paste, and is not particularly limited as long as it is a solvent that dissolves the dispersion transfer accelerator, but organic solvents such as terpene alcohols and aliphatic hydrocarbons are preferable.

  Specific examples of the terpene alcohol-based organic solvent include terpineol (terpineol), dihydroterpineol, terpineol acetate, borneol, geraniol, linalool and the like, and these may be used alone. More than one species may be used in combination.

  Examples of the aliphatic hydrocarbon-based organic solvent include n-decane, n-dodecane, mineral spirit and the like, and these may be used alone or in combination of two or more.

(Nickel organic slurry)
First, the organic solvent and a surfactant containing the dispersion transfer accelerator are mixed to obtain a dispersion transfer accelerator organic solution. Next, the dispersion transfer accelerator organic solution and the nickel powder water slurry are mixed to obtain a nickel organic slurry.

  Here, particularly important in the present invention are (i) the amount of the dispersion transfer accelerator to be added, (ii) the amount S1 of the organic solvent for dissolving this dispersion transfer accelerator and the amount of water W in the nickel powder water slurry. The ratio is S1 / W. As a result, the dispersion transfer accelerator is uniformly coated on the surface of the nickel powder.

(A) Addition amount of dispersion transfer accelerator First, the addition amount of the dispersion transfer accelerator added in (i) is, for example, 1 of the dispersion transfer accelerator to be added calculated by the method described in Non-Patent Document 1. The molecular cross section per molecule (also referred to as the adsorption cross section, which corresponds to the projected area of the molecule on the plane) is used, from which the formula “total surface area of nickel powder (m ² ) × unit molecular break of dispersion transfer promoter” Theoretical calculation amount X value (g) calculated by “mass per area (g / m ² )” (where X is the total surface area of the nickel powder in the present invention = the total molecular cross-sectional area of the dispersion transfer accelerator) Which is the amount of agent). This theoretically calculated amount X value can be regarded as an amount corresponding to the minimum amount of the dispersion transfer accelerator necessary for uniformly adsorbing and coating the entire surface of the nickel powder.

  The molecular cross-section is generally displayed on the same screen as the molecule to be measured for the atoms whose vdw radius is known, such as carbon atoms, by preparing a structurally optimized van der Waals (vdw) radius display. And a calibration curve. The number of dots constituting the ‘circle’ of the atom serving as the calibration curve is measured by image processing software, and the area per dot of the screen is obtained from the vdw radius of the atom and the area of the circle. Next, the number of dots of the molecule whose cross-sectional area is to be measured can be calculated to obtain the molecular cross-sectional area.

  More specifically, according to Non-Patent Document 1, the cross-sectional area in the most stable conformation among the conformations of the dispersion transfer accelerator can be calculated as the molecular cross-sectional area. This non-patent document 1 exemplifies a method for calculating a molecular cross section by taking stearic acid, which is a typical higher fatty acid, as an example. A cross-sectional view of stearic acid is drawn from the structural formula (a) of stearic acid and the space filling model (b) shown in the literature. The cross-sectional area can be obtained by drawing on graph paper using the coupling distance and the van der Waals radius, cutting the paper, and weighing the weight.

In the case of “lauroyl sarcosine, molecular formula C ₁₅ H ₂₉ NO ₃ ”, which is a typical example of the dispersion transfer accelerator used in the present invention, the same as the calculation method of the molecular cross section shown in Non-Patent Document 1 above. As a result, the molecular cross-sectional area of lauroyl sarcosine was found to be 0.00182 g / m ² . The calculation procedure will be specifically described below.

First, when the molar mass is determined from the chemical formula of lauroyl sarcosine, it is 256 g / mol. That is, the weight of one molecule is 4.25E- ²² (g). The cross-sectional area of one molecule is calculated as 2.34E ⁻¹⁵ (cm ² ) = 2.34E ⁻¹⁹ (m ² ). Here, the quantity of lauroyl sarcosine as a dispersion transfer accelerator necessary for coating the surface 1 m ² of the nickel powder is 4.27E ^{+18 in} number and 1.82E ⁻³ g in mass, that is, 0.2%. Calculated as 00182 g / m ² .

Further, the surface area of the Ni powder n (g) of the specific surface area A (m ² / g) used is nAm ² , and by multiplying these, the theoretical calculation amount X value of the dispersion transfer accelerator lauroyl sarcosine is nA × 0.00182. (G) was calculated.

When calculated similarly, in the case of “Lauroylmethyl-β-alanine (molecular formula = C ₁₆ H ₃₁ NO ₃ , CAS No. 21539-57-1), which is another dispersion transfer accelerator that can be used in the present invention. Was found to be 0.00195 g / m ² for coating the surface of the nickel powder with a surface area of 1 m ² .It was also found that “myristoylmethyl-β-alanine (molecular formula = C ₁₈ H ₃₅ NO ₃ , CAS No. 21539-71-9), it was found that the amount of dispersion transfer accelerator necessary to coat the surface 1 m ^{2 of the} nickel powder was 0.00214 g / m ² . In this way, the dispersion transfer accelerator that can be used in the present invention can be calculated by the same method.

  Using the above results, 1 to 4 times the theoretically calculated amount X value of the dispersion transfer promoter lauroyl sarcosine can be added according to the surface area of the nickel powder. If the amount of dispersion transfer accelerator added is less than 1 times the theoretical calculation amount X, the surface of the nickel powder cannot be uniformly covered with the dispersion transfer accelerator, and the water in the organic Ni paste prepared by subsequent kneading treatment will It will remain. If added more than 4 times the theoretical calculation amount X value, the dispersion transfer promoter is superimposed on the nickel powder surface in several layers, so that water is embraced and the residual amount of water increases.

In addition, if it is defined only by the addition amount of the dispersion migration accelerator, the amount of the dispersion migration accelerator necessary for coating the surface 1 m ^{2 of the} nickel powder is 0.00100 g / m, although it varies depending on the type of the dispersion migration accelerator. ² or more and 0.00900 g / m ² or less are preferable, 0.00150 g / m ² or more and 0.00900 g / m ² or less are more preferable, and 0.00182 g / m ² or more and 0.00856 g / m ² or less are particularly preferable.

(Ii) Ratio S1 / W between the amount S1 of the organic solvent and the amount of water W
Moreover, it is necessary to add the dispersion transfer accelerator of the present invention to the nickel slurry after dissolving it in an organic solvent. In the organic solution and water slurry at that time, S ₁ / W which is a ratio of the mass S ₁ of the organic solvent and the mass W of water in the water slurry of the nickel powder is 0.02 <S ₁ / W < Within the range of 0.4.

  When the dispersion transfer accelerator is directly added to the nickel powder water slurry, the dispersion transfer accelerator becomes micelles, and it becomes difficult to efficiently adsorb on the surface of the nickel powder. Therefore, the dispersion transfer accelerator of the present invention is once dissolved in an organic solvent. It is necessary to add to the nickel water slurry.

  As a method for mixing and stirring the dispersion transfer accelerator solution and the nickel water slurry when coating the nickel powder with the dispersion transfer accelerator, known dispersion treatment devices such as a ball mill, a homogenizer, a mortar, an automatic mortar, a kneader, and a planetar are used. Any of a Lee mixer and the like may be used, and is not particularly limited. If necessary, the pressure may be reduced with a vacuum pump or an aspirator to perform defoaming or dehydration. It is also possible to perform heating and cooling processes.

<(B) Water separation step>
In this step (B), the aqueous layer is separated from the nickel organic slurry separated into an aqueous layer and an organic layer to obtain an organic nickel organic slurry. When the nickel organic slurry is obtained by mixing and stirring as described above, the nickel powder in the slurry is dispersed and transferred to the organic layer, and the supernatant water is separated and removed by a conventionally known method to obtain a nickel organic slurry. it can.

  In the organic layer nickel organic slurry separated in this step, about 15 to 50% by mass of water remains, but in the present invention, this residual water can also be reduced in the subsequent kneading step.

<(C) Kneading step>
In the step (C), an organic resin binder is added to the organic layer nickel organic slurry and kneaded. In this step, the residual moisture can be effectively separated and removed by kneading the organic layer nickel organic slurry and the organic resin binder containing the organic vehicle. Specifically, the moisture content by the Karl Fischer method Can obtain a nickel paste of less than 1% by mass.

  The organic resin binder is preferably an organic vehicle obtained by dissolving a resin in an organic solvent. Here, the organic vehicle is obtained by dissolving a resin in an organic solvent, and the resin and the organic solvent may be those usually used for conductive paste applications. For example, the resin has a cellulose structure, a cellulose ester structure. And at least one selected from the group consisting of compounds having a cellulose ether structure.

  The organic solvent is not particularly limited as long as it dissolves the resin. Solvents such as terpene alcohols and aliphatic hydrocarbons are preferable, and are the same as the organic solvent used in the above (A) nickel organic slurry forming step. A thing can use it conveniently. The organic vehicle concentration is not particularly limited but is preferably 10% by mass or more. If it is less than 10% by mass, the viscosity is low and no torque is applied during kneading, and the water separation and removal effect is low.

  As the kneading method, a known kneading method can be used. Specifically, any of a roll mill, a ball mill, a homogenizer, a lyker machine, a kneader, a planetary mixer and the like may be used, and there is no particular limitation. If necessary, the pressure may be reduced with a vacuum pump or an aspirator to perform defoaming or dehydration. It is also possible to perform heating and cooling processes. Thereby, the moisture content of the nickel paste obtained can be made into less than 1 mass% in Karl Fischer moisture content.

  The nickel paste of the present invention may be mixed with, for example, barium titanate as a dielectric that is a constituent component of the multilayer ceramic capacitor after separating and removing residual moisture. Further, it is possible to add a dispersant to increase the dispersibility, and it is also possible to add an organic solvent for adjusting the viscosity. In order to obtain thixotropy, a rheology control agent or the like can be added and kneaded.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example at all.

[Example 1-1]
(1) Step of coating dispersion transfer accelerator on nickel powder First, 100 g of nickel ultrafine powder (standard name: NFP401, average particle size 0.4 μm, specific surface area 1.7 m ² / g) manufactured by JFE Mineral Co., Ltd. is water. 500 g of a nickel powder water slurry having a slurry concentration of 20% by mass was prepared.

  Next, 30 g of dihydroterpineol (manufactured by Nippon Fragrance Co., Ltd.) is prepared as an organic solvent, and then lauroyl sarcosine (trade name, Soypon SLA), an anionic surfactant manufactured by Kawaken Fine Chemical Co., Ltd., is used as a dispersion transfer accelerator. 0.4g of powder was melt | dissolved and 30.4g of dispersion | distribution transfer promoter organic solutions were prepared.

Thereafter, 30.4 g of the dispersion transfer accelerator solution is added to 500 g of the above nickel powder water slurry, and the mixture is mixed and stirred for 2 minutes at a rotational speed of 10 m / s with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.). A migration promoter was coated on the nickel powder. In this way, an organic slurry of nickel powder coated with 1.68 times the theoretically calculated dispersion migration accelerator was obtained (S ₁ /W=0.076).

The above process conditions, a Ni powder surface area 100g is 1.7 × 100 = 170m ^2, the addition amount of dispersing transfer promoter for coating the surface 1 m ² of the nickel powder, as described above 0.00182g / ^m is ^2, theoretically calculated amount X value is calculated to be ^{170 × 0.00182g / m 2 = 0.31g} , dispersing transfer promoter Soipon SLA powder 0.40g was added in example 1, the theoretical calculated amount X The amount is 1.29 times the value.

  Next, ethyl cellulose was added to dihydroterpineol and heated to 80 ° C. with stirring to obtain an organic vehicle (16.7 mass% ethyl cellulose). Next, 36 g of the organic vehicle and 130 g of the nickel powder organic slurry coated with the dispersion transfer accelerator were sufficiently kneaded with three rolls to obtain a nickel paste.

(Measurement of moisture content)
About the obtained nickel paste, the moisture content was as little as 0.38% by mass as a result of measuring the residual moisture at 180 ° C. using a coulometric titration Karl Fischer moisture meter (manufactured by Kyoto Electronics Industry).

<Measurement of dry film density>
The obtained paste was applied onto a PET film to a thickness of 200 μm using an applicator and dried at 120 ° C. for 40 minutes. About the obtained film | membrane, it cut out so that it might be set to (phi) 40mm, the area, the film thickness, and the weight were measured, As a result of calculating the dry film density from these data, the film density as high as 5.7 g / cm < ³ > was obtained.

[Example 1-2]
The addition amount of the dispersion transfer accelerator is 0.60 g, and the nickel powder used is nickel ultrafine powder (standard name: NFP301S, average particle size 0.3 μm, specific surface area 2.6 m ² / g) manufactured by JFE Mineral Co., Ltd. Produced a nickel paste in the same manner as in Example 1-1. The theoretical calculation amount X value was 0.47 g, and the added amount of the dispersion migration accelerator was 1.28 times the theoretical calculation amount X value.

[Example 1-3]
The addition amount of the dispersion transfer accelerator was 0.85 g, and the nickel powder used was nickel ultrafine powder (standard name: NFP201S, average particle size 0.2 μm, specific surface area 3.7 m ² / g) manufactured by JFE Mineral Co., Ltd. Produced a nickel paste in the same manner as in Example 1-1. The theoretical calculation amount X value was 0.67 g, and the added amount of the dispersion transfer accelerator was 1.27 times the theoretical calculation amount X value.

[Example 1-4]
A nickel paste was obtained in the same manner as in Example 1-1 except that the organic vehicle concentration was 25% by mass and 20 g was added.

[Example 1-5]
A nickel paste was obtained in the same manner as in Example 1-1 except that the amount of dispersion transfer accelerator added was 0.80 g and the amount was 2.59 times the theoretical calculation amount X value.

[Example 1-6]
The nickel paste was prepared in the same manner as in Example 1-1, except that the addition amount of the dispersion transfer accelerator was 0.40 g, and the S1 / W ratio when mixing and stirring with the water slurry was 0.076 to 0.15. Obtained.

[Comparative Example 1-1]
Nickel organic slurry was obtained by the same treatment as in Example 1, and then natural filtration and dehydration (manufactured by Toyo Hydraulic Machinery Co., Ltd .: hot plate press ESE-377-00: room temperature, 0.6 MPa × 30 sec, 2 times) were performed. A nickel powder cake coated with a dispersion transfer accelerator was obtained. In this nickel powder cake, the residual moisture was found to be extremely high at 15.2% by mass, and no subsequent evaluation was performed.

[Comparative Example 1-2]
The same material as in Example 1-1 was used, but the Soypon SLA powder, which is a dispersion transfer accelerator, was added directly to the nickel powder water slurry without dissolving it in an organic solvent. Since the powder did not dissolve and could not be coated on the Ni powder surface, the subsequent evaluation was not performed.

[Comparative Example 1-3]
Example 1-1 except that dihydroterpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent is 200 g, and the S ₁ / W ratio when mixing with the nickel powder water slurry is 0.075 to 0.50. In the same manner, a nickel paste was obtained. S ₁ quantity is too large, the water can not be separated even by kneading with an organic vehicle, it was not subjected to further evaluation.

[Comparative Example 1-4]
A nickel paste was obtained in the same manner as in Example 1-1 except that the amount of dispersion transfer accelerator added was 0.10 g and the amount was 0.32 times the theoretical calculation amount X value. Since the amount of dispersion transfer accelerator added was too small, the residual water content was very high at 22.3 mass%, and a paste could not be formed.

[Comparative Example 1-5]
A nickel paste was obtained in the same manner as in Example 1-1 except that the amount of dispersion transfer accelerator added was 1.50 g and the amount was 4.85 times the theoretical calculation amount X value. Since the amount of dispersion transfer accelerator added was too large, the residual water content was extremely high at 16.7% by mass, and a paste could not be formed.

[Comparative Example 1-6]
Example 1-1 except that dihydroterpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent is 5 g, and the S ₁ / W ratio when mixing with the nickel powder water slurry is 0.075 to 0.013. In the same manner, a nickel paste was obtained. Water Many remains for S ₁ amount is too small, it did not mix well by kneading with an organic vehicle.

[Comparative Example 1-7]
A nickel paste was obtained in the same manner as in Comparative Example 6 except that the organic vehicle concentration was 9.1% by mass and 66 g was added. Since kneading was performed using an organic vehicle having a lower concentration than that of Comparative Example 1-6, the amount of water was as high as 17.5% by mass, and the dry film density was 2.3 g / cm ³ . It was low.

  The results of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-7 are collectively shown in Tables 1 to 4.

Next, lauroylmethyl-β-alanine (trade name: Alanon ALA, manufactured by Kawaken Fine Chemical Co., Ltd., the amount of dispersion transfer accelerator necessary to coat 1 m ^{2 of} nickel powder as a dispersion transfer accelerator is 0.00. Example 2-1 to 2-5 and Comparative Examples 2-1 to 2-6 using 00195 g / m ² ) are shown.

[Example 2-1]
First, an ultrafine nickel powder (NR707, average particle size 0.07 μm, specific surface area 14.7 m ² / g) with an average particle size of 0.07 μm by a wet reduction method manufactured by Sumitomo Metal Mining 100 g of an aqueous nickel slurry (nickel powder concentration 20 mass) %) Of 500 g. Next, the total amount of 4.0 g of the dispersion transfer accelerator Alanon ALA powder (manufactured by Kawaken Fine Chemical Co., Ltd.) dissolved in 50 g of an organic solvent (dihydroterpineol, Nippon Fragrance Co., Ltd.) is added to 500 g of the prepared aqueous nickel slurry. did. After that, the nickel organic slurry coated with a dispersion transfer accelerator of 1.40 times the theoretical calculation amount X value was mixed and stirred for 2 minutes at a rotational speed of 10 m / s in peripheral speed with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.). Obtained.

  Next, ethyl cellulose was added to dihydroterpineol and heated to 80 ° C. with stirring to obtain an organic vehicle (25.0 mass% ethyl cellulose). Next, 20 g of the organic vehicle and the nickel powder organic slurry coated with the dispersion transfer accelerator were sufficiently kneaded with a three roll to obtain a nickel paste. The nickel paste obtained in the same manner as in Example 1 was measured for moisture content (Karl Fischer method) and dry film density.

[Examples 2-2 to 2-5]
In Example 2-2, the nickel powder used is nickel ultrafine powder (standard name: NFP201S, average particle size 0.2 μm, specific surface area 3.7 m ² / g) manufactured by JFE Mineral Co., Ltd. The amount was 1.40 times the theoretical calculation amount X value. The S ₁ / W ratio was 0.125, and the vehicle concentration of the obtained nickel paste was 25% by mass.

  In Example 2-3, the same procedure as in Example 2-1 was performed except that the dispersion transfer accelerator was prepared in a predetermined amount shown in Table 2-1, and the amount was 3.50 times the theoretical calculation amount X value.

In Example 2-4, the nickel powder used was nickel ultrafine powder (standard name: NFP401S, average particle size 0.4 μm, specific surface area 1.7 m ² / g) manufactured by JFE Mineral Co., Ltd. The amount was adjusted to 2.41 times the theoretical calculation amount X value. The S ₁ / W ratio was 0.075, and the vehicle concentration of the obtained nickel paste was 16.7% by mass.

In Example 2-5, the nickel powder used was nickel ultrafine powder (standard name: NFP401S, average particle size 0.4 μm, specific surface area 1.7 m ² / g) manufactured by JFE Mineral Co., Ltd. The amount was 1.20 times the theoretical calculation amount X value. The S ₁ / W ratio was 0.150, and the vehicle concentration of the obtained nickel paste was 16.7% by mass.

  Moreover, the nickel paste was produced on the predetermined preparation conditions shown in Table 7 as Comparative Example 2-1 to Comparative Example 2-4.

  The results of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4 are collectively shown in Tables 5 to 8.

Next, as the dispersion transfer accelerator, myristoylmethyl-β-alanine (trade name Alanon AMA, manufactured by Kawaken Fine Chemical Co., Ltd., the amount of the dispersion transfer accelerator necessary to coat the surface 1 m ^{2 of} nickel powder is 0.00. Example 3-1 to 3-5 and Comparative Examples 3-1 to 3-4 using 20021 g / m ² ) are shown.

[Example 3-1]
First, nickel fine powder (standard name: NFP401S, average particle size 0.4 μm, specific surface area 1.7 g / m ² ) is used as nickel powder, and aqueous nickel slurry (nickel powder concentration 20% by mass) is used. 500 g was produced. Next, 20 g of the aqueous nickel slurry prepared was dissolved in 20 g of an organic solvent (dihydroterpineol, manufactured by Nippon Fragrance Co., Ltd.) and 0.4 g of a dispersion transfer accelerator Alanon AMA powder (produced by Kawaken Fine Chemical Co., Ltd.). 4g total amount was added. Thereafter, the mixture was mixed and stirred with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.) at a peripheral speed of 10 m / s for 2 minutes, and the treated nickel organic coated with a dispersion transfer accelerator 1.1 times the theoretical calculation amount X value. A slurry was obtained.

  Next, ethyl cellulose was added to dihydroterpineol and heated to 80 ° C. with stirring to obtain an organic vehicle (16.7% by mass ethyl cellulose). Next, 36 g of the organic vehicle and an organic slurry of nickel powder coated with a dispersion transfer accelerator were sufficiently kneaded with a three roll to obtain a nickel paste. The nickel paste obtained in the same manner as in Example 1 was measured for moisture content (Karl Fischer method) and dry film density.

[Examples 3-2 to 3-5]
In Example 3-2, the nickel powder used was nickel ultrafine powder (standard name: NFP301S, average particle size 0.3 μm, specific surface area 2.6 g / m ² ) manufactured by JFE Mineral Co., Ltd. The amount was adjusted to 1.1 times the theoretical calculation amount X value. Further, the S ₁ / W ratio was set to 0.05, and the vehicle concentration of the obtained nickel paste was set to 16.7% by mass.

In Example 3-3, the nickel powder used was nickel ultrafine powder (standard name: NFP201S, average particle size 0.2 μm, specific surface area 3.7 g / m ² ) manufactured by JFE Mineral Co., Ltd. The amount was adjusted to 1.1 times the theoretical calculation amount X value. Further, the S ₁ / W ratio was set to 0.05, and the vehicle concentration of the obtained nickel paste was set to 16.7% by mass.

In Example 3-4, the nickel powder used was nickel ultrafine powder (standard name: NFP201S, average particle size 0.2 μm, specific surface area 3.7 g / m ² ) manufactured by JFE Mineral Co., Ltd. The amount was adjusted to 1.1 times the theoretical calculation amount X value. The S ₁ / W ratio was 0.025, and the vehicle concentration of the obtained nickel paste was 16.7% by mass.

In Example 3-5, the nickel powder used was nickel ultrafine powder (standard name: NFP201S, average particle size 0.2 μm, specific surface area 3.7 g / m ² ) manufactured by JFE Mineral Co., Ltd. 9 was prepared in a predetermined amount, and the amount was 3.8 times the theoretical calculation amount X value. Further, the S ₁ / W ratio was set to 0.05, and the vehicle concentration of the obtained nickel paste was set to 16.7% by mass.

  Moreover, the nickel paste was produced on the predetermined preparation conditions shown in Table 11 as Comparative Example 3-1 to Comparative Example 3-4.

  The results of Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-4 are collectively shown in Table 9 to Table 12.

  As can be seen from the results of the above Examples and Comparative Examples, the nickel paste obtained within the range of the conditions of the present invention has a dense film with a very low moisture content and a high dry film density. It can be seen that these pastes have no agglomerated powder and are excellent in dispersibility.

Claims (2)

A nickel organic slurry forming step of adding an organic solvent and a surfactant to a nickel powder water slurry;
A water separation step of separating the water layer from the nickel organic slurry separated into an aqueous layer and an organic layer to obtain an organic layer nickel organic slurry;
A step of adding an organic resin binder to the organic layer nickel organic slurry and kneading, and a method for producing a nickel paste,
In the nickel organic slurry forming step, the surfactant contains a dispersion transfer accelerator represented by the following general formula (1) or (2),
The amount of the dispersion transfer accelerator added to the nickel powder is an amount such that the total molecular cross-sectional area of the dispersion transfer accelerator is 1 to 4 times the total surface area of the nickel powder.
S ₁ / W, which is a ratio of the mass S _{1 of the} organic solvent and the mass W of water in the water slurry of the nickel powder, is in the range of 0.02 <S ₁ /W<0.4. A method for producing a nickel paste characterized by the above.

(In general formula (1) or (2), n is an integer of 10 to 20)   The dispersion transfer accelerator is at least one selected from the group consisting of lauroyl sarcosine, lauroylmethyl-β-alanine, myristoylmethyl-β-alanine, cocoyl sarcosineate, myristoyl sarcosinate, palmitoyl sarcosine, stearoyl sarcosine. A method for producing a nickel paste according to 1.