JP2019007032A - Nickel paste, method for producing the same, and method for producing nickel organic slurry - Google Patents

Abstract

To provide a nickel paste dispersed without the flocculation of nickel fine particles and suitably usable as the material for the internal electrode of a multilayer ceramic capacitor, and a method for producing the same.SOLUTION: Provided is a method for producing a nickel paste comprising: a water slurry production step where water is added to nick fine particles with a particle diameter below 100 nm produced by a liquid phase method to produce water slurry; an organic slurry production step where an organic solvent and a dispersion transfer promotor are added to the water slurry, and the same is substituted with the slurry of the organic solvent to produce an organic slurry; a high pressure dispersion step where the organic slurry is subjected to dispersion treatment under the pressure of 100 MPa or higher in the presence of a dispersant; and a pasting step where the organic slurry subjected to the dispersion treatment is subjected to pasting. In the water slurry production step, it is preferable that the water is added in such a manner that the water content in the water slurry reaches 30 to 90 mass%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nickel paste that can be suitably used as a material for an internal electrode of a multilayer ceramic capacitor, for example, and a manufacturing method thereof, and a nickel organic slurry that can be used as a raw material for the nickel paste and a manufacturing method thereof.

  In general, 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 many aggregates of nickel powder. In the production process of nickel powder, it is usual to have a drying step at the final stage regardless of the production method (gas phase method, liquid phase method) of nickel powder. In order to promote agglomeration, the resulting nickel powder generally contains agglomerates produced during drying.

  In recent years, MLCCs are required to increase the number of laminated ceramic green sheets with internal electrode layers from several hundred to about 1000 layers 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 several micron level to the submicron level, and accordingly, the particle size of the nickel powder of the electrode material for the internal electrode has been reduced. Yes.

  However, the smaller the particle size, the larger the surface area of the nickel powder, which increases the surface energy and facilitates the formation of aggregates. In addition, the metal ultrafine powder such as nickel ultrafine powder has poor dispersibility, and when aggregates are present, the nickel powder sinters in the firing step during the production of the ceramic capacitor, and penetrates the ceramic sheet layer. The electrode is short-circuited. Further, even if the ceramic sheet layer cannot be penetrated, the current between the electrodes is reduced due to the short distance between the electrodes, which causes the life of the multilayer ceramic capacitor to deteriorate. As described above, in MLCC, it is important to produce a nickel paste with few coarse particles including aggregates and to obtain a smooth internal electrode having no irregularities on the surface.

  Currently, in vapor phase methods such as thermal CVD (chemical vapor deposition) and plasma CVD, the particle diameters obtained are different (see, for example, the drawing of Patent Document 1), and the average particle diameter is 100 nm or less. The technology for classifying particles is incomplete. Further, the accuracy of classification is not satisfactory, and coarse particles exceeding 100 nm cannot be completely removed. Therefore, a defect due to short-circuit between electrode layers due to coarse particles is a problem.

  On the other hand, nickel nanoparticles synthesized by a liquid phase method have a narrower particle size distribution than those synthesized by a gas phase method, and are therefore suitable for use as a material for the internal electrode described above.

  However, the liquid phase method has a narrow particle size distribution without classification, and even if nickel nanoparticles of 100 nm or less can be synthesized, the surface area is increased by reducing the particle size. May cause fever. In addition, heat generation generates nickel oxide, which also forms a strong aggregate. On the other hand, when the surface of the nickel nanoparticles is oxidized in the water slurry, nickel hydroxide is generated simultaneously with the oxidation of the particle surface, which causes deterioration of electrical characteristics when the nickel paste is formed. It is not preferable as a material for an electrode.

  Such behavior is difficult to handle and may cause product defects. Therefore, for nickel nanoparticles synthesized by the liquid phase method, improvement of the particle surface state is desired.

  Patent Document 2 discloses a technique for oxidizing the surface of nickel particles. Nickel powder produced by a liquid phase method is added to pure water to form a slurry, and then oxidized with hydrogen peroxide. This technical matter is disclosed.

JP 2009-024239 A Japanese Patent Laid-Open No. 11-343501

  The present invention has been proposed in view of such circumstances, and nickel paste that is dispersed without aggregation of nickel fine particles and can be suitably used as a material for an internal electrode of a multilayer ceramic capacitor, and its production It aims to provide a method.

  The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, the aqueous slurry containing the nickel fine particles is replaced with an organic solvent, and the resulting organic solvent slurry is subjected to a high-pressure dispersion treatment to prevent the aggregation of the nickel fine particles. As a result, the present invention was completed.

  (1) The first invention of the present invention is a water slurry production process for producing water slurry by adding water to nickel fine particles having a particle diameter of less than 100 nm produced by a liquid phase method, and an organic solvent is added to the water slurry. An organic slurry production step of producing an organic slurry by adding a dispersion transfer accelerator and replacing the slurry with the organic solvent, and subjecting the organic slurry to a dispersion treatment at a pressure of 100 MPa or more in the presence of the dispersant. It is the manufacturing method of the nickel paste which has a high-pressure dispersion | distribution process and the pasting process which pastes the said organic slurry which performed the dispersion process.

  (2) According to a second aspect of the present invention, in the first aspect, in the water slurry manufacturing step, the nickel fine particles have a water content in the water slurry of 30% by mass or more and 90% by mass or less. It is the manufacturing method of the nickel paste which adds water to.

  (3) According to a third aspect of the present invention, in the first or second aspect, in the organic slurry manufacturing step, the water slurry is 10% by mass or more and 70% by mass or less with respect to 100% by mass of the nickel fine particles. It is the manufacturing method of the nickel paste which adds the organic solvent of this.

  (4) According to a fourth aspect of the present invention, in the first to third aspects of the invention, in the organic slurry manufacturing step, the water slurry is 0.1% by mass with respect to 100% by mass of the nickel fine particles. This is a method for producing a nickel paste in which a dispersion transfer accelerator of 3% by mass or less is added.

  (5) A fifth invention of the present invention is the nickel paste manufacturing method according to any one of the first to fourth inventions, wherein the dispersion treatment is performed in the presence of an oxidizing agent in the high-pressure dispersion step.

  (6) A sixth invention of the present invention is the invention according to any one of the first to fifth inventions, wherein in the high-pressure dispersion step, the dispersing agent is added in an amount of 0.01% by mass or more to 100% by mass of nickel fine particles. It is a manufacturing method of the nickel paste added to the said organic slurry in the ratio used as 0.5 mass% or less.

  (7) A seventh invention of the present invention is a nickel paste manufacturing method for manufacturing a water-in-oil emulsion type organic slurry in the organic slurry manufacturing step according to any one of the first to sixth inventions. .

  (8) The eighth invention of the present invention is the production of a nickel paste according to any one of the first to seventh inventions, wherein the water content in the organic slurry obtained in the organic slurry production step is 3% by mass or less. Is the method.

  (9) A ninth invention of the present invention includes a water slurry production step of producing water slurry by adding water to nickel fine particles having a particle diameter of less than 100 nm produced by a liquid phase method, and an organic solvent is added to the water slurry. An organic slurry production step of producing an organic slurry by adding a dispersion transfer accelerator and replacing the slurry with the organic solvent, and subjecting the organic slurry to a dispersion treatment at a pressure of 100 MPa or more in the presence of the dispersant. And a high-pressure dispersion step.

  (10) A tenth invention of the present invention is a nickel paste containing at least nickel fine particles and a dispersion transfer accelerator, and is printed at 120 ° C. after printing the nickel paste to a film thickness of 30 μm. A nickel film having a gloss value of 150 or more measured at an incident angle of 45 ° according to JIS Z-8741 is cut into a disk shape having a diameter of 40 mm after drying in air for a minute. is there.

  (11) In an eleventh aspect of the present invention, in the tenth aspect, the nickel paste is applied on a glass substrate using an applicator (gap thickness: 5 μm) and then dried in air at 120 ° C. for 5 minutes. The produced dry film having a thickness of 3 μm is a nickel paste having a surface roughness of 0.06 μm or less when measured using an optical interference type surface shape measuring device.

(12) The twelfth invention of the present invention is the drying obtained in the tenth or eleventh invention, after the nickel paste is printed to a film thickness of 30 μm and then dried in air at 120 ° C. for 40 minutes. The membrane is cut into a disk shape having a diameter of 40 mm, the thickness and mass are measured, and the dry organic film density calculated from the thickness and mass is a nickel organic slurry having a dry film density of 5 g / cm ³ or more.

  According to the present invention, there can be provided a nickel paste that can be suitably used as a material for an internal electrode of a multilayer ceramic capacitor and a method for producing the same, in which nickel fine particles are not aggregated and dispersed.

It is a flowchart which shows the flow of the manufacturing process of nickel slurry.

  Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary of this invention, it can change suitably.

<< 1. Manufacturing method of nickel paste >>
The manufacturing method of nickel organic slurry and nickel paste is demonstrated.

  The method for producing nickel fine particles according to the present embodiment includes a water slurry production step of producing water slurry by adding water to nickel fine particles having a particle diameter of less than 100 nm produced by a liquid phase method, and an organic solvent and water slurry. An organic slurry production process for producing an organic slurry by adding a dispersion transfer accelerator and replacing it with an organic solvent slurry, and high-pressure dispersion for subjecting the organic slurry to a dispersion treatment at a pressure of 100 MPa or more in the presence of the dispersant. And a pasting step for pasting the organic slurry subjected to the dispersion treatment.

  Below, this manufacturing method is divided into the following (A) process-(D) process more specifically, and is each demonstrated in detail. That is, as shown in FIG. 1, this nickel paste manufacturing method includes a water slurry manufacturing step (A), an organic slurry manufacturing step (B), a high-pressure dispersion step (C), and a pasting step (D). Of these, the organic slurry production step (B) includes a crushing and mixing treatment step (B-1) and an evaluation step (B-2).

(A) Water slurry production process First, nickel nanoparticles (nickel fine particles) having an average particle size of less than 100 nm, which are starting materials, are prepared. In the present embodiment, nickel fine particles are produced by a liquid phase method, and the nickel fine particles are added to pure water to form an aqueous slurry of nickel fine particles.

  Specifically, examples of the liquid phase method include a wet reduction method using a reducing agent such as hydrazine with respect to a nickel salt solution containing a nickel salt compound. In addition, the nickel fine particle water slurry produced by the liquid phase method is nickel fine particle water slurry manufactured by Sumitomo Metal Mining Co., Ltd., standard name: NR707 (nickel ultrafine particles by wet reduction method, average particle size 70 nm), etc. Is commercially available and can be used effectively.

  Although it does not specifically limit as addition amount of water, It is preferable to add so that the water content in a water slurry may be 30 to 90 mass%, and it is added so that it may be 35 to 85 mass% More preferably, it is more preferably added so that it may become 35 to 75 mass%, and it is especially preferable that it is 40 to 60 mass%. A water slurry can be efficiently manufactured by adding water so that water content may be 30 mass% or more and 90 mass% or less. Moreover, the time which an organic slurry manufacturing process requires can be shortened by adding water so that water content may be 80 mass% or less.

(B) Organic slurry manufacturing process (B-1) Crushing and mixing process Next, an organic solvent is added to the obtained aqueous slurry of nickel fine particles to perform substitution treatment, and the nickel fine particles are dispersed in the organic solvent. The “nickel organic slurry” (hereinafter also referred to as “organic slurry”) is generated.

  Specifically, the replacement treatment with an organic solvent is performed by adding a predetermined amount of an organic solvent and a dispersion transfer agent to an aqueous slurry of nickel fine particles, and using a homogenizer, an ultrasonic homogenizer, a ball mill, a mortar, an automatic mortar, a planetary mixer, etc. The nickel fine particles are crushed to mix the water slurry, the organic solvent, and the dispersion transfer agent. Thereby, the nickel water slurry is replaced with the nickel organic slurry.

  The nickel water slurry is in a state where the nickel water slurry and the oil are separated only by adding the organic solvent and the dispersion transfer accelerator (oil). For example, the peripheral speed is 10 m / s with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.). By carrying out the crushing and mixing treatment with stirring at a rotational speed of, the dispersion transfer accelerator can be adsorbed on the surface of the nickel fine particles and dispersed in the organic solvent. That is, since the surface of the nickel fine particles of the nickel water slurry is hydrophilic, the nickel fine particles are moved from the aqueous phase to the oil phase by modifying the surface to be lipophilic by the dispersion transfer accelerator. Thus, the nickel fine particles can be separated from the water by changing to an oil-in-water (W / O) emulsion containing nickel fine particles in the oil phase.

  In the present invention, the “water-in-oil (W / O) type” refers to a state in which nickel fine particles containing 3% by mass or less of residual moisture are dispersed in the oil phase, and no residual moisture is contained. It is a concept that also includes the state (0% by mass).

  Thus, the water-in-oil (W / O) type emulsion is not particularly limited as long as it can contain 3% by mass or less of residual moisture in the oil phase. As content, it is preferable that it is 1 mass% or less.

  In this way, after the nickel fine particles are phase-inverted to the water-in-oil (W / O) type by the crushing and mixing process, the nickel fine particles are dissolved in the organic solvent by removing water by vacuum filtration or centrifugation. A dispersed nickel organic slurry is obtained.

[Organic solvent]
The organic solvent is not particularly limited as long as it can replace the nickel water slurry with an organic solvent slurry. Specifically, for example, terpineol, dihydroterpineol, dihydroterpineol acetate, isobornyl propionate, isobornyl isobutyrate, mineral spirit, No. 0 solvent, butyl carbitol, isobutyl acetate, methyl ethyl ketone, cyclohexane, hexane, Examples include ethanol, nonane, nonanol, decanol and the like. _Furthermore, C _n H _2n + _2, can _{C n H 2n,} C n H aliphatic hydrocarbon represented by _2n-2, also be used aromatic hydrocarbons such as represented by C _{n H 2n-6,} specifically Examples thereof include dimethyloctane, ethylmethylcyclohexane, methylpropylcycloheptane, trimethylhexane, butylcyclohexane, tridecane, tetradecane, methylnonane, ethylmethylheptane, trimethyldecane, pentylcyclohexane, decane, undecane, dodecane, and toluene. These organic solvents can be used alone or in combination of two or more.

  The addition amount of the organic solvent is not particularly limited. For example, it is preferably 10% by mass to 70% by mass and more preferably 15% by mass to 70% by mass with respect to 100% by mass of the nickel fine particles. The content is more preferably 20% by mass or more and 65% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less. When the addition amount of the organic solvent is 10% by mass or more and 70% by mass or less, the nickel organic slurry can be efficiently produced.

[Dispersion transfer accelerator]
As the dispersion transfer accelerator, a surfactant or a dispersant having a polymer structure can be used. Here, since the surface of the nickel fine particles has basic properties, the dispersion transfer accelerator has an anionic surfactant structure or a functional group (acid group) such as carboxylic acid. Those having a high polymer structure can be used. That is, the dispersion transfer accelerator having such a structure efficiently adsorbs to the surface of the nickel fine particles, and moves the nickel fine particles from the aqueous phase to the oil phase by modifying the nickel fine particle surface to be lipophilic. Can do. Moreover, the dispersibility in a nickel paste can also be improved.

(Dispersion migration accelerator having an anionic surfactant structure)
Specifically, as the dispersion transfer accelerator having an anionic surfactant structure, for example, any one of the compounds (1) to (3) having a specific structure represented by the following general formula can be used. .

  Here, regarding the compounds represented by the general formulas (1) and (2), “n” in the formula is an integer of 10 to 20. When the number of n is smaller than 10, hydrophilicity becomes strong, and there is a possibility that water is difficult to escape during kneading in the production of the nickel paste. On the other hand, if the number of n is larger than 20, it becomes lipophilic and easily removes water, but it is difficult to dissolve in an organic solvent and the surface of nickel fine particles may not be efficiently coated.

For example, the compound represented by the general formula (1) and represented by the structural formula when n = 10 is specifically a compound represented by the following structural formula (1-1). The compound represented by the structural formula (1-1) has a chemical name “lauroyl sarcosine” (molecular formula = C ₁₅ H ₂₉ NO ₃ , CAS No. = 97-78-9), and is a commercially available interface. It is an activator.

As other compounds, the chemical name “lauroylmethyl-β-alanine” (structural formula: (2-1) below, molecular formula: C ₁₆ H ₃₁ NO ₃ , CAS No. 21539-57-1) and the chemical name “ Specific examples include “myristoylmethyl-β-alanine” (structural formula: (2-2) below, molecular formula: C ₁₈ H ₃₅ NO ₃ , CAS No. 21539-71-9). Further, 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 ), stearoyl sarcosine (general formula (1), molecular formula: C ₂₁ H ₄₁ NO ₃ ) and the like.

  Moreover, regarding the compound represented by the general formula (3), “m” and “n” in the formula satisfy the relationship of m + n = 12 to 20. If m + n is less than 12, the lipophilicity is insufficient and water separation may be insufficient. On the other hand, if m + n is larger than 20, it may be difficult to dissolve in an organic solvent.

Specifically, the compound represented by the general formula (3) has a molecular formula of C ₂₁ H ₃₉ NO ₃ and a structural formula of the following (3-1) (however, in the general formula (3), m = 7, n = 7), the chemical name “N-oleyl-N-methylglycine” (hereinafter also referred to as “oleoylsarcosine”), and the molecular formula is C ₁₉ H ₃₅ NO ₃ (however, in general The chemical name “N-palmitolein-N-methylglycine”, which is m = 7 and n = 5 in formula (3), and the molecular formula is C ₂₁ H ₃₉ NO ₃ (however, in general formula (3) The chemical name is “N-baxene-N-methylglycine” with m = 9, n = 5), and the molecular formula is C ₂₇ H ₅₁ NO ₃ (where m = 13, n = 7) and the chemical name “N-Nervon-N-methylglycine” It can be.

(Dispersion transfer accelerator having a polymer structure)
Further, as the dispersion transfer accelerator having a polymer structure, for example, a dispersion transfer accelerator having a polymer structure having a functional group (acid group) such as carboxylic acid at the terminal or in the molecule is used. be able to.

  Specifically, examples of the dispersion migration accelerator having a polymer structure having a functional group (acid group) such as carboxylic acid at the terminal include a urethane polymer dispersant. In addition, as a urethane type polymer dispersing agent, a brand name: Solsperse 55000 (average molecular weight 55000), a brand name: Solsperse 36000 (average molecular weight 36000), a brand name: Solsperse 21000 (average molecular weight 21000), etc. are marketed (all are Japan). Lubrizol Co., Ltd.) can be used preferably. Further, a single carboxylic acid type trade name: Solsperse 3000 (manufactured by Nippon Lubrizol Co., Ltd.) can also be used effectively.

  Further, the structure of the dispersion transfer accelerator is not particularly limited, but a comb polymer is particularly preferable. The dispersion transfer accelerator having a comb-like structure has a carboxylic acid group in the anchor portion and a polyoxyalkylene group in the graft portion, and has a structure in which the balance between hydrophobicity and hydrophilicity differs depending on the composition. In addition, as a polymer dispersing agent which is a comb polymer, for example, Marialim AWC series and SC series manufactured by NOF Corporation are commercially available.

  The addition amount of the dispersion transfer accelerator is not particularly limited. For example, it is preferably 0.1% by mass or more and 3% by mass or less, and 0.2% by mass or more and 3% by mass with respect to 100% by mass of the nickel fine particles. More preferably, it is more preferably 0.5% by mass or more and 3% by mass or less. When the addition amount of the dispersion transfer accelerator is 0.1% by mass or more and 3% by mass or less, the nickel organic slurry can be efficiently produced.

  The crushing and mixing treatment time is not particularly limited, and can be appropriately set depending on the apparatus to be used. For example, the crushing and mixing treatment time is preferably 1 to 5 minutes.

(B-2) Evaluation step Although not an essential aspect, in the evaluation step, the behavior of phase transition and the residual moisture in the nickel organic slurry are confirmed for the nickel organic slurry obtained in the crushing and mixing treatment step.

  The behavior of the phase transition of the nickel water slurry can be confirmed by thermal mass measurement. Specifically, measurement is performed with a thermal analyzer (manufactured by Bruker AXS: TG-DTA2010SA) at a temperature range of 20 to 300 ° C. and a heating rate of 10 ° C./min. In the obtained thermal profile, when there is no inflection point in weight reduction to around 150 ° C., the nickel fine particles move from the aqueous phase to the oil phase, and phase inversion into a water-in-oil (W / O) type emulsion occurs. Can be determined. On the other hand, if there is an inflection point (two steps) up to around 150 ° C., it is determined that the nickel fine particles have not completely moved to the oil phase and have not formed a water-in-oil (W / O) emulsion. can do.

  The residual moisture content of the nickel organic slurry is determined by measuring the residual moisture content at 180 ° C. of the nickel organic slurry using a coulometric titration Karl Fischer moisture meter (manufactured by Kyoto Electronics Industry Co., Ltd.). Is preferably used in a later step.

(C) High-pressure dispersion step In the high-pressure dispersion step, the nickel organic slurry obtained in the organic slurry production step is subjected to dispersion treatment (high-pressure dispersion treatment) under a pressure of 100 MPa or more. Thus, by performing a dispersion treatment on the organic slurry under a predetermined pressure, the aggregate (floc) remaining in the nickel organic slurry containing nickel fine particles can be efficiently crushed, Dispersibility in the slurry can be increased.

  The pressure in the high pressure dispersion treatment is 100 MPa or more. Moreover, it is preferable that it is 100 MPa or more and 200 MPa or less. If the pressure is less than 100 MPa, fine particles may be insufficiently dispersed. On the other hand, when the pressure is 200 MPa or less, the apparatus cost and the operation cost can be suppressed.

  The high-pressure dispersion treatment can be performed using an apparatus capable of performing a wet process while applying pressure. For example, a wet atomization apparatus, a high-pressure emulsification apparatus, or the like can be used.

  The conditions for the dispersion treatment can be appropriately selected with respect to the concentration of the nickel organic slurry, the chamber nozzle diameter of the apparatus, the pressure, the number of passes, and the like. For example, in the case of the optimizer system HJP25005, a highly dispersible (highly dispersed) organic slurry can be obtained with a chamber nozzle diameter of 0.12 mm, a pressure of 100 MPa, and a number of passes of 5 times.

  When performing the high pressure dispersion treatment, the nickel organic slurry to be treated may be diluted with an organic solvent. The organic solvent used for dilution is not particularly limited as long as it can dilute nickel organic slurry, and for example, the same organic solvent used as a dispersion medium for nickel organic slurry can be used.

  Here, in the high pressure dispersion step, a dispersant is added to the nickel organic slurry, and the dispersion treatment is performed in the presence of the dispersant. In this way, the dispersant is adsorbed on the active surface (new surface) of the nickel fine particles crushed by the high-pressure dispersion treatment by adding the dispersant to the nickel organic slurry and applying the high-pressure dispersion treatment in the presence of the dispersant. Thus, the dispersibility of the nickel fine particles can be enhanced, re-aggregation can be suppressed, and a nickel organic slurry having a sharper particle size distribution can be obtained. Moreover, since reaggregation can be suppressed, the number of high-pressure dispersion treatments can be reduced.

  The dispersant is not particularly limited as long as it can disperse nickel fine particles in an organic solvent. For example, the same dispersant as the above-described dispersion transfer accelerator can be used. Specifically, for example, a dispersant having an anionic surfactant structure of (1) to (3) having the specific structure shown in the above general formula (however, shown in the above general formulas (1) and (2)) Regarding the compound, “n” in the formula is an integer of 10 to 20. Further, regarding the compound represented by the general formula (3), “m” and “n” in the formula have a relationship of m + n = 12 to 20. Or a dispersant having a polymer structure can be used.

  More specifically, examples of the dispersant having the anionic surfactant structure represented by the general formula (1) include lauroyl sarcosine, cocoyl sarcosine, myristoyl sarcosine, palmitoyl sarcosine, stearoyl sarcosine, and the like. It is done. Examples of the dispersant having an anionic surfactant structure represented by the general formula (2) include lauroylmethyl-β-alanine and myristoylmethyl-β-alanine. Furthermore, as a dispersant having an anionic surfactant structure represented by the general formula (3), for example, oleoylsarcosine, N-palmitolein-N-methylglycine, N-baxene-N-methylglycine, N- Nervon-N-methylglycine and the like can be mentioned.

  In addition, examples of the dispersant having a polymer structure include a urethane-based polymer dispersant.

  The addition amount of the dispersant is not particularly limited, and is preferably 0.01% by mass or more and 5.5% by mass or less, and more preferably 0.02% by mass or more and 5% by mass or less with respect to 100% by mass of the nickel fine particles. It is more preferable that it is 0.05 mass% or more and 4.5 mass% or less, and it is especially preferable that it is 0.1 mass% or more and 4 mass% or less. When the addition amount of the dispersant is 0.01% by mass or more, the dispersibility of the nickel fine particles can be improved and aggregation can be suppressed. Moreover, when the addition amount of the dispersing agent is 5.5% by mass or less, the viscosity of the nickel paste becomes more appropriate, and a nickel paste with good operability can be obtained.

  The method for adding the dispersant is not particularly limited, and for example, it can be added to the organic slurry as a powder or a solution. Also, the addition time is not particularly limited as long as it is after the organic slurry manufacturing process and before the dispersion treatment.

  In the high-pressure dispersion step or the subsequent stage, an oxidizing agent can be further added to the nickel organic slurry. As described above, by further adding an oxidizing agent, the nickel fine particles dispersed in the organic slurry can be oxidized, and an oxide film containing nickel oxide can be formed on the surface thereof. Thereby, aggregation of nickel fine particles can be prevented more efficiently.

  The oxidizing agent is not particularly limited, and hydrogen peroxide, ozone, or the like can be used. However, it is preferable to use hydrogen peroxide from the viewpoint of being low in cost and easy to handle because it is in the form of a solution.

  Specifically, in this oxidation treatment, an oxidizing agent such as hydrogen peroxide is added little by little to the nickel organic slurry and stirred. For example, when hydrogen peroxide is used as the oxidizing agent, hydrogen peroxide water can be added and used. As for the amount of addition, it is preferable to add hydrogen peroxide in a proportion of 0.01 g or more and 20 g or less, and in a proportion of 0.05 g or more and 15 g or less, with respect to 1 g of nickel fine particles present in the nickel organic solvent slurry. It is more preferable to add at a ratio of 0.1 g to 10 g. The amount of hydrogen peroxide can be calculated by converting the amount contained in the hydrogen peroxide solution.

  Further, when a gas such as ozone is used as the oxidant, the oxidant can be supplied to the slurry by bubbling the slurry. For example, when ozone is used as the oxidizing agent, the amount of ozone generated is not particularly limited, and is preferably 10 mg / hr or more and 300 mg / hr or less, for example. When the ozone generation amount is 10 mg / hr or more, a sufficient amount of ozone can be supplied for oxidation of the nickel surface. On the other hand, when the amount of ozone generated is 300 mg / hr or less, the cost of equipment, power, etc. for generating ozone can be suppressed. Moreover, it does not specifically limit as time to perform a bubbling process, For example, it is preferable that they are 5 minutes or more and 120 minutes or less. Note that ozone can be generated by, for example, an ozone generator.

  The method for adding the oxidizing agent is not particularly limited, and for example, it can be added to the organic slurry as a powder or a solution. Also, the addition time is not particularly limited as long as it is after the organic slurry manufacturing process and before the pasting process. When performing high-pressure dispersion treatment in multiple steps, the high-pressure dispersion treatment can be performed from the beginning in the presence of an oxidant, or after the high-pressure dispersion treatment in the absence of an oxidant, an oxidant is added in the middle. The high-pressure receiving process can be performed, or the oxidizing agent can be added and oxidized after all the high-pressure dispersion processes are completed.

(D) Pasting step In the pasting step, the nickel organic slurry that has been subjected to the dispersion treatment in the high-pressure dispersion step is made into a paste. Specifically, a nickel paste can be produced by adding and kneading, for example, an organic vehicle composed of an organic solvent and a resin to an organic slurry in which nickel fine particles are dispersed.

  The raw material nickel organic slurry can be concentrated and used according to the paste composition. As a method for concentrating the nickel organic slurry, a known technique such as removing an organic solvent with a centrifuge, an evaporator, or the like can be used.

≪2. Nickel paste >>
The nickel paste according to the present embodiment is obtained by the manufacturing method described above, and contains at least nickel fine particles and a dispersion transfer accelerator. And in this nickel paste, the gloss value (glossiness) measured based on JIS Z-8741 is 150 or more with respect to the dry film formed using the said nickel paste.

  Specifically, the gloss value is determined by printing a nickel paste on a PET film so as to have a film thickness of 30 μm in an area of 5 × 10 cm, and then drying in air at 120 ° C. for 40 minutes to form a dry film. Using a test film obtained by cutting the film into a disk shape having a diameter of 40 mm, an incident angle of 45 ° can be measured with a portable spectrocolorimeter. The gloss value becomes higher as the dispersibility of the nickel paste is better and the surface of the formed dry film is smoother. Such a gloss value is preferably 155 or more, more preferably 160 or more, further preferably 165 or more, and particularly preferably 170 or more.

  Thus, the nickel paste according to the present embodiment has a gloss value of 150 or more of the dry film formed, that is, there is almost no aggregation of nickel fine particles and high dispersibility.

  Such a nickel paste can be suitably used as a material used for an internal electrode of a multilayer ceramic capacitor (MLCC) mounted on a form device such as an automobile or a mobile phone. In addition, according to such a nickel paste, since there are very few coarse particles including aggregates, the surface of the internal electrode is smooth without any irregularities, and therefore, the occurrence of short circuits between the internal electrode layers of the MLCC occurs. Can be prevented. Furthermore, according to such a nickel paste, nickel fine particles can be densely aggregated, and the density of the dry film obtained is high by sintering in such a densely aggregated state.

  The surface roughness (Ra) of the dry film formed from such a nickel paste is preferably 0.06 μm or less, more preferably 0.05 μm or less, and 0.04 μm or less. Further preferred. Further, the maximum value (Ra (Max)) of the surface roughness of the dry film is preferably 0.39 μm or less, more preferably 0.37 μm or less, and further preferably 0.35 μm or less. preferable. In addition, a dry film | membrane is obtained by making it dry in air at 120 degreeC for 5 minutes after apply | coating on a glass substrate using an applicator (gap thickness 5 micrometers), and setting it as a film thickness of 3 micrometers. The surface roughness and its maximum value are values obtained by measurement using an optical interference type surface shape measuring apparatus.

The density of the dry film formed using such a nickel paste is preferably 5 g / cm ³ or more. The dry film density is calculated by printing on a PET film so that the film thickness is 30 μm, drying in air at 120 ° C. for 40 minutes, cutting into a disk shape with a diameter of 40 mm, measuring the thickness and mass, and calculating the dry film density. Is the value to be

  As the viscosity of the nickel paste, the viscosity measured at a rotation speed of 10 rpm is preferably 20 Pa · s or more and 60 Pa · s or less. “Viscosity” refers to a value that can be measured, for example, with a B-type viscometer.

[Nickel fine particles]
The nickel fine particles are a constituent component of the nickel paste. Such nickel fine particles can be suitably used, for example, as an internal electrode of a multilayer ceramic capacitor.

  Such nickel fine particles can be produced by a so-called liquid phase method such as a wet reduction method using a reducing agent such as hydrazine for a nickel salt solution.

  The particle diameter of the nickel fine particles is preferably an ultrafine particle having an average particle diameter of less than 100 nm. By using nickel fine particles having an average particle size of less than 100 nm, for example, a nickel paste that can cope with the thinning required recently as an internal electrode of MLCC can be produced.

  The nickel fine particles can be provided with an oxide film (nickel oxide) having a thickness (film thickness) of 1 nm or more, more preferably 5 nm or more on the particle surface. The thickness of the oxide film on the particle surface can be appropriately set according to the application. For MLCC, there is no particular limitation because there is a heat treatment step in a reducing atmosphere in the subsequent step. However, for example, the thickness may be about 20 nm or less as long as the conductivity is not affected. With such an oxide film, even when the average particle size is a small particle size of 100 nm or less, aggregation of particles can be more effectively prevented, and formation of aggregates can be prevented.

  The content of the nickel fine particles is not particularly limited, and for example, the ratio of the mass of the nickel fine particles to the mass of the organic solvent (nickel fine particles: organic solvent) is preferably 10 to 90:90 to 10.

[Dispersion transfer accelerator]
The dispersion transfer accelerator is adsorbed and coated on the surface of the nickel fine particles, and acts to improve the dispersibility in the nickel paste. As the dispersion transfer accelerator, the above-described dispersion transfer accelerator having an anionic surfactant structure or a dispersion transfer accelerator having a polymer structure can be used. Here, the surface of the nickel fine particles has a basic property. Therefore, by using a dispersion transfer accelerator having an anionic surfactant structure or a dispersion transfer accelerator having a polymer structure as a dispersion transfer accelerator, it can be efficiently adsorbed on the surface of nickel fine particles. Can be improved.

  In the nickel paste according to the present embodiment, the content of the dispersion transfer accelerator is preferably in the range of 0.16% by mass to 3.0% by mass with respect to 100% by mass of the nickel powder. When the content of the dispersion transfer accelerator is 0.16% by mass or more with respect to 100% by mass of the nickel fine particles, the amount of adsorption to the nickel fine particles can be increased, and as a result, the dispersibility of the nickel fine particles can be further increased. it can. On the other hand, when the content of the dispersion transfer accelerator is 3.0% by mass or less, a change in the viscosity of the nickel paste accompanying an increase in the amount of the dispersion transfer accelerator can be prevented.

[Vehicle]
The nickel paste can contain a vehicle. The vehicle is obtained by dissolving a raw material binder resin in an organic solvent. In such a nickel paste, the dispersion transfer accelerator and the binder contained in the vehicle adsorbed on the surface of the nickel fine particles by containing the vehicle containing the specific binder resin and the vehicle containing the specific binder resin. With the resin, the dispersibility of the nickel fine particles can be effectively improved, and the nickel ultrafine particles can be dispersed with very little aggregation.

  Specifically, the binder resin has, for example, a structure selected from a cellulose structure, a cellulose ester structure, and a cellulose ether structure, and has at least one functional group (acid group) such as a carboxyl group introduced therein. Can be used.

  Thus, as the binder resin, for example, it is preferable that a functional group (acid group) such as carboxylic acid is introduced, and the acid amount is 20 μmol / g or more and 300 μmol / g or less. Is preferred. When the acid amount is 20 μmol / g or more, the adsorption amount to the nickel fine particles can be increased, and as a result, the dispersibility of the nickel fine particles can be further increased. On the other hand, when the acid amount of the binder resin is 300 μmol / g or less, an increase in the viscosity of the nickel paste to be produced can be suppressed, and for example, a viscosity that is easy to handle as an internal electrode of MLCC can be obtained.

  The concentration of the binder resin in the vehicle is not particularly limited, but is preferably 5% by mass or more. When the concentration of the binder resin in the vehicle is 5% by mass or more, a decrease in viscosity can be suppressed.

  The organic solvent is not particularly limited as long as it dissolves the above-described binder resin, and those usually used for conductive paste applications can be used. For example, the same organic solvent as described above can be used as the dispersion medium for the nickel organic slurry.

[Others]
In addition, the nickel paste which concerns on this Embodiment can be made to contain various additives as needed in the range which does not impair the effect | action. Specifically, a dispersant for further improving the dispersibility of the nickel fine particles, a viscosity modifier for adjusting the viscosity, a rheology control agent for improving thixotropy, and the like can be added. Further, for example, various materials such as a dielectric such as barium titanate can be added as a co-material.

≪3. Nickel organic slurry >>
The nickel organic slurry according to the present embodiment is a nickel organic slurry containing at least nickel fine particles and a dispersion transfer accelerator, and the median diameter (D ₅₀ ) of the particles contained in the nickel organic slurry is 700 nm or less. It is. In addition, such a nickel organic slurry can be obtained by the manufacturing method of the nickel organic slurry as described above, for example.

  The median diameter is not particularly limited, but is preferably 600 nm or less, more preferably 500 nm or less, further preferably 400 nm or less, and particularly preferably 300 nm or less. The smaller the median diameter, the smaller the surface roughness of the dried film and the higher the dried film density, and the more suitable the material used for the internal electrode of MLCC.

  Moreover, such a nickel organic slurry can be used as a raw material for producing the nickel paste as described above.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

≪Evaluation method≫
The nickel pastes obtained under the production conditions shown in the following examples and comparative examples were evaluated by the following evaluation methods.

[Evaluation of viscosity]
The viscosity of 10 rpm was measured for the prepared paste with a Brookfield viscometer, and a value of 20 to 60 Pa · s was evaluated as ◯ (good), and the other was evaluated as x (bad).

[Surface roughness (Ra)]
An Ni paste is applied on a glass substrate using an applicator (gap thickness 5 μm), and then dried in air at 120 ° C. for 5 minutes to produce a dry film having a thickness of about 3 μm.

  With respect to this dry film, surface protrusions were measured by an optical method using a phase shift interference method. Specifically, the sample and the reference mirror are irradiated with light from a light source limited to a specific wavelength region, and the surface state is observed by interference fringes of the light irradiated to the sample and the reference mirror. The surface state is observed from the interference fringes of the light by moving the light in the direction in which the light is irradiated every quarter wavelength. The surface roughness of the dried film was measured using an optical interference type surface shape measuring device (WYKO-NT1100 manufactured by Nitto Kogyo Co., Ltd.).

[Dry film density (DFD)]
The dry film density was obtained by printing nickel paste on a PET film so as to have a film thickness of 30 μm in an area of 5 × 10 cm, dried in air at 120 ° C. for 40 minutes, and cut into a disk shape having a diameter of 40 mm, The thickness and mass were measured and calculated.

[Gloss measurement (Glossiness measurement)]
The gloss was obtained by printing a nickel paste on a PET film so as to have a film thickness of 30 μm in an area of 5 × 10 cm, followed by drying in air at 120 ° C. for 40 minutes and cutting into a disk shape having a diameter of 40 mm. The dry film was measured using a portable spectrocolorimeter (BYK Gardner / Spectro Guide 45/0 manufactured by Toyo Seiki Seisakusho Co., Ltd.). A gloss value of 150 or higher was evaluated as ◯ (good), and a value less than 150 was evaluated as x (bad).

<< 1. (C) Verification of the effect of the presence or absence of high-pressure dispersion treatment process »
(C) In order to verify the effect of the presence or absence of the high-pressure dispersion treatment step, a nickel slurry was produced according to the following Reference Examples 1 to 15 and Comparative Examples 1 to 3. In Reference Examples 1 to 15 and Comparative Examples 1 to 3, no dispersant was added.

[Reference Example 1]
<(A) Nickel water slurry manufacturing process>
First, 200 g of nickel fine particle water slurry manufactured by Sumitomo Metal Mining Co., Ltd. (water content 50 mass%) (standard name: NR707, Ni fine particles by wet reduction method, average particle size 70 nm) was prepared as a starting material.

<(B) Organic slurry manufacturing process>
[(B-1) Crushing and mixing process]
Next, 200 g of nickel fine particle water slurry (water content 50% by mass), 30 g of terpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent (30% by mass with respect to nickel fine particles), and oleoyl sarcosine (day) as a dispersion transfer accelerator 1 g (1% by mass with respect to nickel fine particles) was added and mixed gently, and then stirred for 2 minutes with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.) at a peripheral speed of 10 m / s. Thereafter, the stirred slurry was separated into water and a nickel organic slurry by vacuum filtration to obtain a nickel organic slurry.

[(B-2) Evaluation step]
Next, the phase inversion state and the residual moisture content were confirmed about the obtained nickel organic slurry.
The phase inversion state was measured from 20 ° C. to 300 ° C. with a temperature increase rate of 10 ° C./min in a nitrogen atmosphere by thermo mass measurement TG-DTA2010SA (manufactured by Bruker AXS). As a result, there was no inflection point in the decrease to 150 ° C., and it was confirmed to be a water-in-oil (W / O) type emulsion.

  The residual moisture content was measured with a coulometric titration Karl Fischer moisture meter (manufactured by Kyoto Electronics Industry). The sample was held at 180 ° C. for 20 minutes in a nitrogen atmosphere, and the residual water content was measured. As a result, the residual moisture was measured, and as a result, it was very low at 0.75% by mass.

<(C) High pressure dispersion process>
Terpineol was added to the obtained nickel organic slurry to dilute it three times, and dispersion treatment was performed using an optimizer system HJP25005 (manufactured by Sugino Machine Co., Ltd.). Treating the whole amount of the nickel organic slurry diluted three times with a chamber nozzle diameter of 0.12 mm and a pressure of 150 MPa as one pass, and performing the pass five times, a highly dispersed nickel organic slurry was obtained. As a result, the number-based median diameter (D ₅₀ ) measured using a laser diffraction scattering method was 200 nm.

<(D) Pasting step>
The obtained highly dispersed nickel organic slurry was concentrated to 1/3 of the solvent using an evaporator. The nickel organic after concentration so that the composition of the nickel paste is 46.8% by mass of nickel fine particles, 10.5% by mass of co-material (barium titanate), 3.5% by mass of ethyl cellulose, and 39.2% by mass of solvent. Add organic vehicle (ethylcellulose: terpineol = 10: 90) adjusted to 10% by mass and co-material to the slurry, disperse with 3 rolls, and add No. 0 Solvent (manufactured by JX Nippon Oil & Energy Corporation). The viscosity was adjusted to prepare a nickel paste. The No. 0 solvent contains 99% by volume or more of saturated hydrocarbon and contains tridecane, nonane and cyclohexane as main components.

[Reference Example 2]
In the organic slurry manufacturing step, 0.5 g of oleoyl sarcosine (manufactured by NOF Corporation) as a dispersion transfer accelerator is added to 200 g of nickel fine particle water slurry (water content 50 mass%) (0.5 mass% based on nickel fine particles). A nickel paste was prepared in the same manner as in Reference Example 1 except that it was added.

[Reference Example 3]
In the organic slurry manufacturing process, except that 3 g of oleoyl sarcosine (manufactured by NOF Corporation) as a dispersion transfer accelerator was added to 200 g of nickel fine particle water slurry (water content 50 mass%) (3 mass% based on nickel fine particles). A nickel paste was prepared in the same manner as in Reference Example 1.

[Reference Example 4]
Reference Example 1 except that in the organic slurry production process, 25 g (25% by mass with respect to nickel fine particles) of terpineol (manufactured by Nippon Fragrance Co., Ltd.) was added as an organic solvent to 200 g of nickel fine particle water slurry (water content 50% by mass). Similarly, a nickel paste was produced.

[Reference Example 5]
Reference Example 1 except that in the organic slurry manufacturing process, 40 g of terpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent was added to 200 g of nickel fine particle water slurry (water content 50 mass%) as an organic solvent. Similarly, a nickel paste was produced.

[Reference Example 6]
A nickel paste was prepared in the same manner as in Reference Example 1 except that 200 g of nickel fine particle water slurry (water content 40 mass%) was used as a starting material.

[Reference Example 7]
A nickel paste was prepared in the same manner as in Reference Example 1 except that 200 g of nickel fine particle water slurry (water content 60 mass%) was used as a starting material.

[Reference Example 8]
A nickel paste was prepared in the same manner as in Reference Example 1 except that the nickel organic slurry was treated at a pressure of 200 MPa in the high pressure dispersion step.

[Reference Example 9]
A nickel paste was prepared in the same manner as in Reference Example 1 except that the nickel organic slurry was treated at a pressure of 245 MPa in the high pressure dispersion step.

[Reference Example 10]
A nickel paste was produced in the same manner as in Reference Example 1 except that the treatment was performed 20 times in the high-pressure dispersion step.

[Reference Example 11]
In the organic slurry production process, 10 g (10% by mass with respect to nickel fine particles) of terpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent was added to 200 g of nickel fine particle water slurry (water content 50% by mass) and an Excel auto homogenizer. A nickel paste was prepared in the same manner as in Reference Example 1 except that stirring was performed for 32 minutes.

[Reference Example 12]
In the organic slurry manufacturing process, 90 g (90% by mass with respect to nickel fine particles) of terpineol (manufactured by Nippon Fragrance Co., Ltd.) as an organic solvent was added to 200 g of nickel fine particle water slurry (water content 50% by mass), and an Excel auto homogenizer. A nickel paste was prepared in the same manner as in Reference Example 1 except that stirring was performed for 42 minutes.

[Reference Example 13]
A nickel paste was prepared in the same manner as in Reference Example 1 except that 200 g of nickel fine particle water slurry (water content 30 mass%) was used as a starting material.

[Reference Example 14]
A nickel paste was prepared in the same manner as in Reference Example 1, except that 200 g of nickel fine particle water slurry (water content: 90% by mass) was used as a starting material, and stirring was performed with an Excel auto homogenizer for 62 minutes.
[Reference Example 15]
The same as Reference Example 3 except that a polymer dispersant (trade name: Solsperse 36000, manufactured by Nippon Lubrizol Co., Ltd.) having a phosphate group as a hydrophilic group and a polyamide as a lipophilic group was used as a dispersion transfer accelerator. Thus, a nickel paste was produced.

[Comparative Example 1]
A nickel paste was prepared in the same manner as in Reference Example 1 except that no dispersion transfer accelerator was used in the organic slurry production process.

[Comparative Example 2]
A nickel paste was prepared in the same manner as in Reference Example 1 except that the organic slurry was not subjected to high-pressure dispersion treatment (the number of passes was 0).

[Comparative Example 3]
A nickel paste was prepared in the same manner as in Reference Example 1 except that the nickel organic slurry was treated at a pressure of 50 MPa in the high pressure dispersion step.

  In Table 1, the manufacturing conditions of the nickel paste in Reference Examples 1-15 and Comparative Examples 1-3 are shown. Table 2 shows the results of measuring the viscosity, dry film density, surface roughness, and gloss of the nickel pastes obtained in Reference Examples 1 to 15 and Comparative Examples 1 to 3.

  As a result of verification, it was found that a nickel paste in which nickel fine particles are not dispersed can be obtained by subjecting the organic slurry to high-pressure dispersion treatment under a pressure of 100 MPa or more.

≪2. Verification of the effect of adding a dispersant >>
Next, in order to verify the effect of adding a dispersant to the organic slurry in the (C) high-pressure dispersion step, a nickel slurry was produced according to Examples 1 to 8 below.

[Example 1]
(C) In the high-pressure dispersion step, after adding terpineol to the obtained nickel organic slurry and diluting it three times, reference was made except that 1% by mass of oleoylsarcosine was added as a dispersant to 50% by mass of nickel fine particles. A nickel paste was prepared in the same manner as in Example 1.

[Example 2]
(C) Nickel in the same manner as in Example 1 except that 1% by mass of lauroyl sarcosine (trade name: Soypon SLA, manufactured by Kawaken Fine Chemical Co., Ltd.) was added to 50% by mass of nickel fine particles as a dispersant in the high-pressure dispersion step. A paste was prepared.

[Example 3]
(C) In the high-pressure dispersion step, Example 1 except that 1% by mass of lauroylmethyl-β-alanine (trade name: Alanon ALA, manufactured by Kawaken Fine Chemical Co., Ltd.) was added to 50% by mass of nickel fine particles as a dispersant. Similarly, a nickel paste was produced.

[Example 4]
(C) In the high pressure dispersion step, Example 1 except that myristoylmethyl-β-alanine (trade name: Alanon AMA, manufactured by Kawaken Fine Chemical Co., Ltd.) was added in an amount of 1% by mass with respect to 50% by mass of nickel fine particles. Similarly, a nickel paste was produced.

[Example 5]
(C) In the high-pressure dispersion step, a nickel paste was prepared in the same manner as in Example 1 except that 5% by mass of oleoyl sarcosine as a dispersant was added to 50% by mass of the nickel fine particles.

[Example 6]
(C) In the high-pressure dispersion step, nickel was added in the same manner as in Example 1 except that 5% by mass of lauroyl sarcosine (trade name: Soypon SLA, manufactured by Kawaken Fine Chemical Co., Ltd.) was added as a dispersant to 50% by mass of nickel fine particles. A paste was prepared.

[Example 7]
(C) In the high-pressure dispersion step, the same as Example 1 except that 5% by mass of lauroylmethyl-β-alanine (trade name: ALA, manufactured by Kawaken Fine Chemical Co., Ltd.) was added to 50% by mass of nickel fine particles as a dispersant. Thus, a nickel paste was produced.

[Example 8]
(C) Other than the addition of 5% by mass of nickel-based fine particles of 50% by mass of myristoylmethyl-β-alanine (trade name: Alanon AMA, manufactured by Kawaken Fine Chemical Co., Ltd.) with respect to nickel during high-pressure emulsification treatment. A nickel paste was prepared in the same manner as in Example 1.

  In Table 3, the manufacturing conditions of the nickel paste in Examples 1-8 are shown. Table 4 shows the results of measuring the viscosity, dry film density, surface roughness, and gloss of the nickel pastes obtained in Examples 1 to 8. For comparison, Table 3 also shows the manufacturing conditions of Reference Example 1, and Table 4 also shows the evaluation results of the nickel paste obtained in Reference Example 1.

As a result of the verification, the particle diameter (D ₅₀ ) of the nickel fine particles is smaller by adding a dispersant to the organic slurry and subjecting the organic slurry to high-pressure dispersion treatment than when no dispersant is added (Reference Example 1). It was found that a nickel paste with less aggregation can be obtained. Moreover, since the gloss value of the obtained dry film surface showed a higher value, it was found that the dispersibility of the nickel fine particles was extremely good.

Claims (12)

A water slurry production step of producing water slurry by adding water to nickel fine particles having a particle diameter of less than 100 nm produced by a liquid phase method;
An organic slurry production step of producing an organic slurry by adding an organic solvent and a dispersion transfer accelerator to the water slurry and replacing the slurry with the organic solvent;
A high-pressure dispersion step of subjecting the organic slurry to a dispersion treatment under a pressure of 100 MPa or more in the presence of a dispersant;
And a pasting step for pasting the organic slurry that has been subjected to the dispersion treatment. The method for producing a nickel paste according to claim 1, wherein, in the water slurry production step, water is added to the nickel fine particles so that a water content in the water slurry is 30% by mass or more and 90% by mass or less. The method for producing a nickel paste according to claim 1 or 2, wherein, in the organic slurry production step, an organic solvent of 10% by mass or more and 70% by mass or less is added to the water slurry with respect to 100% by mass of the nickel fine particles. In the said organic slurry manufacturing process, 0.1 to 3 mass% of dispersion | distribution transfer promoters are added to the said water slurry with respect to 100 mass% of the said nickel fine particles. The manufacturing method of the nickel paste of description. The method for producing a nickel paste according to claim 1, wherein in the high-pressure dispersion step, a dispersion treatment is performed in the presence of an oxidizing agent. The said high pressure dispersion | distribution process WHEREIN: The said dispersing agent is added to the said organic slurry in the ratio used as 0.01 mass% or more and 5.5 mass% or less with respect to 100 mass% of nickel fine particles. The manufacturing method of the nickel paste as described in a term. The method for producing a nickel paste according to any one of claims 1 to 6, wherein in the organic slurry production step, a water-in-oil emulsion type organic slurry is produced. The method for producing a nickel paste according to any one of claims 1 to 7, wherein a water content in the organic slurry obtained in the organic slurry production step is 3% by mass or less. A water slurry production step of producing water slurry by adding water to nickel fine particles having a particle diameter of less than 100 nm produced by a liquid phase method;
An organic slurry production step of producing an organic slurry by adding an organic solvent and a dispersion transfer accelerator to the water slurry and replacing the slurry with the organic solvent;
A high-pressure dispersion step of subjecting the organic slurry to a dispersion treatment in the presence of a dispersant under a pressure of 100 MPa or more. A nickel paste containing at least nickel fine particles and a dispersion transfer accelerator,
After printing the nickel paste to a film thickness of 30 μm, the dried film obtained by drying in air at 120 ° C. for 40 minutes is cut into a disk shape with a diameter of 40 mm, in accordance with JIS Z-8741. Nickel paste having a gloss value of 150 or more measured at an incident angle of 45 °. The nickel paste is applied onto a glass substrate using an applicator (gap thickness 5 μm), and then dried in air at 120 ° C. for 5 minutes. The nickel paste according to claim 10, wherein the surface roughness when used is 0.06 μm or less. After the nickel paste is printed to a thickness of 30 μm, the dried film obtained by drying in air at 120 ° C. for 40 minutes is cut into a disk shape having a diameter of 40 mm, and the thickness and mass are measured. The nickel paste according to claim 10 or 11, wherein the dry film density calculated from the mass is 5 g / cm ³ or more.

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