JP2016191084A - Surface treated copper fine particle and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treated copper fine particle excellent in oxidation resistance, capable of forming sintered film having good conductivity even with sintering at low temperature and capable of being manufactured with simple processes.SOLUTION: There is provided a surface treated copper fine particle excellent in oxidation resistance and having low temperature sinterability and having average particle diameter of 0.1 to 1.0 μm by mixing a copper fine particle obtained by conducting a chemical reduction method or a disproportionation reaction in a presence of a particle growth inhibitor with a solution containing a nitrogen containing organic article of 0.03 to 10 wt.% based on the copper fine particle after mixing with diluted sulfuric acid or without mixing with diluted sulfuric acid. There is provided a surface treated copper fine particle where the nitrogen containing organic article is a compound exemplified by the following formula.SELECTED DRAWING: None

Description

  The present invention relates to a surface-treated copper fine particle and a method for producing the same.

[Metal powder paste]
Electrodes and circuits in conventional electronic components are formed by bonding a copper foil to an insulating substrate, or forming a metal layer by plating on the entire surface of the substrate and then etching or electroless plating using patterning on the insulating substrate. In recent years, from the viewpoint of resource saving and cost, attention has been paid to the formation of electrodes and circuits using a metal powder paste that can supply a metal source as much as necessary.

[Characteristics of metal powder]
From the viewpoint of manufacturing cost and heat load on the material, the metal powder paste is desired to be fired at a low temperature. For this purpose, small metal powder is preferable.

[Silver powder paste]
Among metal powder pastes, silver powder paste has low electrical resistance and can be fired even in the atmosphere. However, when electrodes and circuits are formed with silver powder paste, there is a concern about migration. Moreover, since it is a noble metal, material cost increases. Therefore, a copper powder paste has been studied.

[Copper powder paste]
On the other hand, copper is more easily oxidized than silver. Therefore, copper powder is easier to oxidize than silver powder. Since the surface area is increased by reducing the size, the small copper powder is easily oxidized, and the surface copper oxide layer becomes a sintering obstacle. In order to sinter the copper powder paste at a low temperature, a treatment for preventing oxidation of the copper powder has been studied.

[Treatment to prevent oxidation of copper powder]
As a process for preventing the oxidation of the copper powder, there is a process for adsorbing a substance on the surface of the copper powder. Patent Document 1 discloses a technique for adsorbing fatty acids such as oleic acid on the surface of copper powder. Since these are difficult to dissolve in water, they must be adsorbed on copper powder after being dispersed in an organic solvent. Alternatively, the reaction field is an organic solvent, and an organic substance to be coated on the copper powder surface is dispersed in the solvent in advance, and then the organic substance is attached to the copper powder surface in the growth stage after the nucleation during the milling reaction. There is also a method in which an organic solvent itself acts as a coating (Patent Documents 2 and 3). Alternatively, there is a method in which a water-soluble polymer such as polyvinylpyrrolidone is present in the reaction field as a protective colloid, and copper oxide is reduced with a reducing agent to obtain copper fine particles (Patent Documents 3 and 4).

JP 2002-332502 A JP 2012-072418 A International Publication No. WO2007 / 013393 JP 2004-256857 A

  Since the copper powder of the paste for low-temperature sintering is submicron in size, it cannot be handled by an electrolytic method or an atomizing method, and is obtained using a chemical reaction. In this milling reaction, a grain growth inhibitor is adhered to the surface of the copper powder in order to prevent coarsening of the particles. Examples of the grain growth inhibitor include natural resins, polysaccharides, gelatin and the like. The present inventor has obtained knowledge that it is necessary to remove these grain growth inhibitors when an organic substance is adhered to prevent oxidation of copper powder. For this purpose, a removal operation step using an organic solvent or an alkaline aqueous solution is required, resulting in an increase in the number of steps. Therefore, it is desirable that the grain growth inhibitor can be removed without increasing the number of steps.

  Further, as in the prior art, when copper fine particles are obtained by reducing copper oxide or a copper compound with a reducing agent, the reaction temperature must be 60 ° C. or higher. Thus, when temperature rises, the particle growth inhibitor in a reaction field and a surface treating agent will become difficult to adsorb | suck to copper fine particles. For this reason, it is necessary to add a grain growth inhibitor and a surface treatment agent to the reaction field excessively beforehand. However, if added in excess, not only the amount adsorbed directly on the copper fine particles, but also the amount physically adsorbed on the compound adsorbed on the copper fine particles exists, so the amount of organic matter covering the copper fine particles is Become more. This can be an obstacle to sintering. Furthermore, since a large amount of grain growth inhibitor and surface treatment agent are required, a process for treating excess organic matter in the waste liquid is required. Therefore, it is desirable that the oxidation of the copper powder can be prevented without excessively using the grain growth inhibitor and the surface treatment agent.

  Accordingly, the object of the present invention is to provide a surface having an average particle diameter of 1 μm or less, excellent in oxidation resistance, capable of forming a fired film having good conductivity even when sintered at a low temperature, and manufactured by a simple process. The object is to provide treated copper particulates.

  As a result of diligent research so far, the present inventor has conducted a surface treatment by mixing an aqueous solution containing a specific nitrogen-containing organic substance and copper fine particles. The inventors have found that surface-treated copper fine particles having sinterability can be obtained, and reached the present invention.

Accordingly, the present invention includes the following (1).
(1)
Copper fine particles obtained by performing a chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor,
Surface-treated copper fine particles obtained by mixing with an aqueous solution containing 0.03 to 10% by weight of a nitrogen-containing organic substance with respect to the copper fine particles.
(2)
After mixing copper fine particles obtained by performing chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor with dilute sulfuric acid,
Furthermore, the surface-treated copper fine particle obtained by mixing with the aqueous solution containing 0.03-10 weight% of nitrogen containing organic substance with respect to copper fine particle.
(3)
The surface-treated copper fine particles according to (1) or (2), wherein the aqueous solution containing a nitrogen-containing organic substance is an alkaline aqueous solution.
(4)
Nitrogen-containing organic matter
An amino acid; or any of the following groups:
—CH (OH) —CH ₂ —NR ¹ R ² group (where R ¹ and R ² are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- It is a group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group and a C3 to C8 linear or branched alkenyl group. )
Or —CH (OH) —CH ₂ — [N ⁺ R ¹ R ² R ³ ] X ₁ ^— group (where R ¹ , R ² and R ³ are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- A group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group, a C3-C8 linear or branched alkenyl group,
X ₁ ⁻ is a monovalent anion selected from the group consisting of a halide ion and CH ₃ SO ₄ ^— )
The surface-treated copper fine particles according to any one of (1) to (3), which are amine compounds having one or more of
(5)
Nitrogen-containing organics have the following formula I:
(Where n is an integer of 1 to 8,
The R group is any of the following groups:
—NR ¹ R ² group (where R ¹ and R ² are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- It is a group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group and a C3 to C8 linear or branched alkenyl group. )
Or-[N ⁺ R ¹ R ² R ³ ] X ₁ ^- group (wherein R ¹ , R ² and R ³ are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- A group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group, a C3-C8 linear or branched alkenyl group,
X ₁ ⁻ is a monovalent anion selected from the group consisting of halide ions and CH ₃ SO ₄ ^— ))
The surface-treated copper fine particle according to any one of (1) to (4), which is a nitrogen-containing organic substance represented by:
(6)
The surface-treated copper fine particles according to any one of (1) to (5), wherein the grain growth inhibitor is at least one selected from natural resins, polysaccharides, and gelatin.
(7)
The surface-treated copper fine particles according to any one of (1) to (6), wherein the average particle diameter of the copper fine particles is in the range of 0.1 to 1.0 μm.
(8)
The surface-treated copper fine particles according to any one of (1) to (7), wherein the copper fine particles have a cuprous oxide layer on at least a part of the particle surface.
(9)
A surface-treated copper fine particle according to any one of (1) to (8); and a copper fine particle paste comprising alcohol or glycol having a boiling point of 250 ° C. or lower.
(10)
Furthermore, the copper fine particle paste as described in (9) containing an acrylic resin or rosin.
(11)
A fired body having a specific resistance of 50 μΩcm or less, obtained by firing the copper fine particle paste according to (9) or (10) at 350 ° C. or less in a non-oxidizing atmosphere.

(21)
Copper fine particles obtained by performing a chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor,
A step of mixing with an aqueous solution containing 0.03 to 10% by weight of nitrogen-containing organic matter with respect to the copper fine particles,
A method for producing surface-treated copper fine particles.
(22)
A step of mixing copper fine particles obtained by performing a chemical reduction method or a disproportionation reaction in the presence of a grain growth inhibitor with dilute sulfuric acid to obtain dilute sulfuric acid-treated copper fine particles,
Mixing the dilute sulfuric acid-treated copper fine particles with an aqueous solution containing 0.03 to 10% by weight of nitrogen-containing organic matter with respect to the copper fine particles,
A method for producing surface-treated copper fine particles.
(23)
(21) or a step of mixing the surface-treated copper fine particles produced by the method according to (22) with an alcohol or glycol having a boiling point of 250 ° C. or lower to obtain a copper fine particle paste;
A method for producing a copper fine particle paste.
(24)
(21) or a step of mixing the surface-treated copper fine particles produced by the method according to (22) with an alcohol or glycol having a boiling point of 250 ° C. or lower, an acrylic resin, or rosin to obtain a copper fine particle paste;
A method for producing a copper fine particle paste.
(25)
A step of obtaining a fired body by firing the copper fine particle paste produced by the method according to (23) or (24) at 350 ° C. or lower in a non-oxidizing atmosphere;
A method for producing a fired body.

  According to the present invention, surface-treated copper fine particles having excellent oxidation resistance and low-temperature sinterability can be obtained by a simple process. According to the present invention, a conductive paste capable of forming a fired film having good conductivity even when sintered at a low temperature can be obtained using highly economical copper fine particles.

The present invention will be described in detail below with reference to embodiments. The present invention is not limited to the specific embodiments described below.
[Production of surface-treated copper fine particles]
The surface-treated copper fine particles according to the present invention comprise 0.03 to 10% by weight of copper fine particles obtained by performing a chemical reduction method or a disproportionation reaction in the presence of a grain growth inhibitor. It can manufacture by the method of including the process of mixing with the aqueous solution containing nitrogen-containing organic substance.

  Further, the surface-treated copper fine particles according to the present invention are obtained by mixing copper fine particles obtained by chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor with dilute sulfuric acid. It can be produced by a method comprising a step of obtaining fine particles and a step of mixing dilute sulfuric acid-treated copper fine particles with an aqueous solution containing 0.03 to 10% by weight of a nitrogen-containing organic substance with respect to the copper fine particles.

[Copper fine particles]
The copper fine particles to be surface-treated in the present invention are copper fine particles obtained by performing a chemical reduction method or a disproportionation reaction in the presence of a grain growth inhibitor. The copper fine particles may or may not have a cuprous oxide layer on at least a part of the particle surface.

[Chemical reduction, disproportionation reaction]
The chemical reduction method or the disproportionation reaction can be performed by a known means to obtain fine copper particles.

[Average particle size]
In a preferred embodiment, copper fine particles having an average particle diameter of copper fine particles in the range of, for example, 0.1 to 1.0 μm can be suitably surface-treated.

[Grain growth inhibitor]
In the chemical reduction method or the disproportionation reaction, a grain growth inhibitor is used in order to obtain fine copper particles. The grain growth inhibitor is not particularly limited as long as it is a water-soluble polymer, and examples thereof include one or more selected from natural resins, polysaccharides, and gelatin.

[Diluted sulfuric acid-treated copper fine particles]
In a preferred embodiment, the copper fine particles obtained by performing a chemical reduction method or a disproportionation reaction in the presence of a grain growth inhibitor are mixed with dilute sulfuric acid to form dilute sulfuric acid-treated copper fine particles, and then the surface It can be used as copper fine particles to be treated. Mixing with dilute sulfuric acid can be performed, for example, by mixing dilute sulfuric acid in the range of 0.1N to 30N while irradiating copper powder with stirring or ultrasonic waves. The copper fine particles treated with dilute sulfuric acid can be separated from the slurry containing dilute sulfuric acid by a known means and then subjected to a mixing treatment with an aqueous solution containing a nitrogen-containing organic substance.

[Aqueous solution containing nitrogen-containing organic substances]
In a preferred embodiment, the aqueous solution containing a nitrogen-containing organic substance is an alkaline aqueous solution.

[Nitrogen-containing organic matter]
In a preferred embodiment, the nitrogen-containing organic substance is an amino acid or an amine compound. The nitrogen-containing organic substance is used so as to have a ratio of, for example, 0.03 to 10% by weight, 0.05 to 10% by weight, 0.1 to 10% by weight, and 0.4 to 10% by weight with respect to the copper fine particles. it can. From the step of obtaining copper fine particles by performing chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor to the step of mixing with an aqueous solution containing a nitrogen-containing organic substance, etc. From the viewpoint of workability, instead of using the nitrogen-containing organic substance in an amount within the above-mentioned range of the weight percent with respect to the copper fine particles, the nitrogen-containing organic substance is used as a copper compound (for example, cuprous oxide) as a raw material for the copper fine particles , Copper oxide, etc.) can be used in an amount within the above-mentioned range of weight%.

[amino acid]
The amino acid may be a so-called natural amino acid or a non-natural artificial amino acid, and an amino acid further having an amino group or imino group as a side chain is preferable. Examples of amino acids include Trp, Asn, Arg, His, and Lys. As amino acids, polymers of these amino acids can also be used. In a preferred embodiment, the amino acid polymer as a whole can be water-soluble.

[Amine compound]
As the amine compound, a tertiary amine compound or a quaternary amine compound can be used. As such an amine compound, an amine compound having a —CH (OH) —CH ₂ —NR ¹ R ² group or a —CH (OH) —CH ₂ — [N ⁺ R ¹ R ² R ³ ] X ₁ ^— group Can be mentioned. These groups may have, for example, one or more, or 3 to 16, 3 to 12, 3 to 8, and 4 to 6 in the amine compound.

[Suitable amine compound skeleton]
Such amine compounds include the following formula I:
(Wherein, the R group is any of the following groups: -NR ¹ R ² group or-[N ⁺ R ¹ R ² R ³ ] X ₁ ^- group)
Can be preferably used. In the formula, n can be an integer of 1 to 8, preferably an integer of 1 to 6, and an integer of 2 to 4.

[R ¹ , R ² , R ³ ]
R ¹ and R ² are each independently, or R ¹ , R ² and R ³ are each independently a C1-C8 alkyl group, a C1-C8 hydroxyalkyl group, a C2-C8 alkoxyalkyl group. C7 to C10 substituted or unsubstituted phenylalkyl group, C6 to C8 substituted or unsubstituted phenyl group, C12 to C16 substituted or unsubstituted naphthyl group, C3 to C8 linear or branched alkenyl group A group selected from the group consisting of In a preferred embodiment, R ¹ and R ² can be the same group. In a preferred embodiment, R ³ can be, for example, a group having an aromatic ring. In preferred embodiments, these substituents are selected such that the amine compound as a whole has water solubility.

  An alkyl group can be made into C1-C8 (C1-C8), C1-C6, C1-C3, C1-C2, for example. The hydroxyalkyl group can be, for example, C1-C8, C1-C6, C1-C3, C1-C2. The alkoxyalkyl group can be, for example, C1-C8, C1-C6, C1-C3, C1-C2, and can be, for example, a methoxyalkyl group, an ethoxyalkyl group, or a propoxyalkyl group. The phenylalkyl group can be, for example, C7 to C10 and C7 to C8, and the phenyl group of the phenylalkyl group may be a substituted or unsubstituted phenyl group. For example, the phenyl group of the phenylalkyl group is a C1 to C3 alkyl group. One or two groups may be substituted with a group. The phenyl group may be, for example, C6 to C8 or C6 to C7, and may be a substituted or unsubstituted phenyl group, and may be substituted by one or two, for example, a C1 to C3 alkyl group. A naphthyl group can be made into C12-C16, C12-C14, for example, may be a substituted or unsubstituted naphthyl group, for example, may be substituted 1 or 2 by a C1-C3 alkyl group. The alkenyl group can be, for example, C3-C8, C3-C6, C3-C4, and may have a linear or branched skeleton.

[X ₁ ^-]
X ₁ ⁻ is a monovalent anion selected from the group consisting of halide ions and CH ₃ SO ₄ ⁻ .

[Examples of amine compounds]
In addition to the above amine compounds of the formula I, for example, the following backbone amine compounds can be exemplified:

A11:

A12:

A13:

A14:

A15:

A16:

A17:

A18:

B11:

B12:

B13:

B14:

B15:

B16:

B17:

B18:

In the amine compounds exemplified above, R ₁ , R ₂ , R ₃ and X ₁ ⁻ described above can be used as R ¹ , R ² , R ³ and X ₁ ⁻ .

[Surface treated copper fine particles]
After the copper fine particles are surface-treated by mixing with an aqueous solution containing a nitrogen-containing organic substance, the copper fine particles are appropriately separated from the aqueous solution by known means, dried and crushed as necessary, and then the conductive paste (copper) As a form suitable for the production of a fine particle paste), surface-treated copper fine particles can be obtained.

[Low temperature sintering]
The surface-treated copper fine particles of the present invention are excellent in low temperature sinterability. For example, when a copper fine particle paste is used, for example, a sintering temperature of 400 ° C. or lower, 350 ° C. or lower, 300 ° C. or lower, 250 ° C. or lower, for example 200 An excellent fired body can be obtained at a sintering temperature of not lower than 230 ° C, not lower than 230 ° C, and not lower than 250 ° C.

[Copper fine particle paste]
By using the surface-treated copper fine particles, a conductive paste (copper fine particle paste) can be produced by a known means. In a preferred embodiment, for example, surface-treated copper fine particles can be mixed with alcohol or glycol having a boiling point of 250 ° C. or lower to obtain a copper fine particle paste. A binder resin may be added to the paste to adjust the viscosity. Since the copper fine particles are baked in a non-oxidizing atmosphere or a reducing atmosphere, the binder resin is preferably a pyrolytic binder resin. Suitable binder resins include acrylic resins and rosins. Or you may use a well-known solvent, an additive, and a glass frit if it desires in the range which does not prevent the outstanding low-temperature sintering property. If the glass frit is larger than the copper fine particles, it becomes an obstacle when a flat coating film is formed. Therefore, the D50 is preferably less than 20 times the D50 of the copper fine particles. Mixing can be carried out by known means, and may be carried out by one stage or two or more stages of kneading.

[Firing body]
Using the copper fine particle paste, it is possible to produce a fired body by performing coating or the like and firing by a known means. In a preferred embodiment, for example, a copper fine particle paste can be fired at 350 ° C. or lower in a non-oxidizing atmosphere to obtain a fired body.

[atmosphere]
Sintering can be performed, for example, in a non-oxidizing atmosphere or a reducing atmosphere. The non-oxidizing atmosphere refers to an atmosphere in which an oxidizing gas is not contained or reduced, for example, an atmosphere in which oxygen is completely or sufficiently removed. The reducing atmosphere contains 0.5 vol% or more, preferably 1.0 vol% or more of a reducing gas such as CO, H ₂ S, SO ₂ , H ₂ , HCHO, HCOOH, and H ₂ O in the atmosphere. Say the atmosphere. As reducing atmosphere, the atmosphere containing gaseous nitrogen and gaseous hydrogen of atmospheric pressure can be mentioned, for example.

[Resistivity]
The copper fine particle paste according to the present invention reflects the excellent low-temperature sinterability of the surface-treated copper fine particles, and can produce a fired body excellent in specific resistance even by sintering at a low temperature. The specific resistance [μΩ · cm] of the fired body can be measured by the means described in the examples. In a preferred embodiment, the specific resistance value is, for example, 15 μΩ · cm or less at a sintering temperature of 350 ° C., 20 μΩ · cm or less at a sintering temperature of 300 ° C., and 44 μΩ · cm or less at a sintering temperature of 250 ° C. Can do.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

(Example 1: Synthesis of amine (A1 to A6))
Amine compounds (A1 to A6) were synthesized as nitrogen-containing organic substances (organic substances) by the following procedure. 10.0 g of epoxy compound (Denacol EX-521 (manufactured by Nakase ChemteX Corporation)) and 5.72 g of diethanolamine were put into a three-necked flask, and a cooling tube using dry ice-methanol as a cooling medium was prepared. The reaction was carried out for 3 hours to obtain a compound modified with diethanolamine. The structure of the obtained diethanolamine compound is as follows.

  In the same manner, compounds modified with bis (2-ethoxyethyl) amine, dibenzylamine, diphenylamine, diallylamine, and dimethylamine, respectively, were passed. The structure of the product was identified by FT-IR, 1H-NMR, and 13C-NMR. Hereinafter, a diethanolamine compound, a dimethylamine compound, a bis (2-ethoxyethyl) amine compound, a dibenzylamine compound, a diphenylamine compound, and a diallylamine compound are denoted as A1 to A6, respectively.

(Example 2: Synthesis of amine (B1 to B6))
Amine compounds (B1 to B6) were synthesized as nitrogen-containing organic substances (organic substances) by the following procedure. 10.0 g of epoxy compound (Denacol EX-521 (manufactured by Nakase ChemteX Corporation)) and 5.72 g of diethanolamine were put into a three-necked flask, and a cooling tube using dry ice-methanol as a cooling medium was prepared. The reaction was allowed to proceed for 3 hours. Thereafter, the cooling pipe was removed, and nitrogen gas was blown into the reaction solution to remove excess diethanolamine. Finally, 6.88 g of benzyl chloride was added to the reaction solution and reacted at 100 ° C. for 3 hours. The structure of the product was identified by FT-IR, 1H-NMR, and 13C-NMR. The structure of the obtained diethanolamine compound is as follows.

  In the same manner, compounds modified with bis (2-ethoxyethyl) amine, dibenzylamine, diphenylamine, diallylamine, and dimethylamine, respectively, were passed. The structure of the product was identified by FT-IR, 1H-NMR, and 13C-NMR. Hereinafter, a diethanolamine compound, a dimethylamine compound, a bis (2-ethoxyethyl) amine compound, a dibenzylamine compound, a diphenylamine compound, and a diallylamine compound are denoted as B1 to B6, respectively.

  The structures of the synthesized compounds A1 to A6 and B1 to B6 are structural formulas in which n = 3 in the following formula I and the R group is substituted as shown in Table 1 below.

Formula I:

(Example 3: Examples 1 and 30)
In a 1 L beaker, 50 g of cuprous oxide powder and 0.25 g of animal glue made from gum arabic or fish as a protective agent (grain growth inhibitor) are dispersed in 350 mL of pure water, and a volume ratio of 25% 100 mL of sulfuric acid was added instantaneously to carry out a disproportionation reaction. Decantation and water washing were repeated from this slurry to obtain 20 g of copper fine particles having a D50 of 0.2 μm. After 20 g of this copper fine particle and 100 mL of an aqueous solution containing 1 g of amine A2 as an organic substance (nitrogen-containing organic substance) were mixed at 300 rpm for 1 hour, copper fine powder was recovered. Then, after drying at 70 degreeC in nitrogen for 1 hour, it was crushed and the surface-treated copper fine particle was obtained. The copper fine particles were mixed with diethylene glycol and three rolls so that the metal ratio was 85%, and screen-printed on a glass substrate so that the dry coating thickness was about 10 μm. This was fired in N ₂ at each temperature of 350 ° C., 300 ° C., and 250 ° C. for 30 minutes, and the specific resistance of the obtained fired body was measured.

(Example 4: Examples 2-29 and 31, Comparative Examples 2-7, Reference Examples 1-6)
In a 1 L beaker, 50 g of cuprous oxide powder and 0.25 g of animal glue made from gum arabic or fish as a protective agent (grain growth inhibitor) are dispersed in 350 mL of pure water, and diluted in sulfuric acid with a volume ratio of 25%. 100 mL was added instantaneously to carry out a disproportionation reaction. Decantation and water washing were repeated from this slurry to obtain 20 g of copper fine particles having a D50 of 0.2 μm. The copper fine particles were dispersed in 0.1 mol / L dilute sulfuric acid for 10 minutes, and the copper fine particles were recovered by decantation. After 20 g of this copper fine particle and 100 mL of an aqueous solution containing various compounds as organic substances (nitrogen-containing organic substances) were mixed at 300 rpm for 1 hour, copper fine powder was recovered. Then, after drying at 70 degreeC in nitrogen for 1 hour, it was crushed and the surface-treated copper fine particle was obtained. The paste was prepared by the procedure of Example 3, and the resistance of the fired body was measured.

(Example 5: Example 32)
In a 2 L beaker, 79.6 g of copper oxide powder and 0.40 g of gum arabic as a protective agent (grain growth inhibitor) are dispersed in 500 mL of pure water, and water is adjusted to pH 8.5 ± 0.1 at a liquid temperature of 50 ° C. Sodium oxide was added for adjustment. To this, 500 mL of an aqueous solution containing 50.5 g of hydrazine monohydrate was added instantaneously, and the solution was stirred at 300 rpm for 30 minutes. During this time, the liquid temperature was maintained at 50 ° C. ± 0.1 ° C. and the pH at 8.5 ± 0.1. Thereafter, decantation and water washing were repeated to obtain 63 g of copper fine particles. After mixing 100 mL of an aqueous solution containing 1.59 g of amine A2 as an organic substance (nitrogen-containing organic substance) at 300 rpm for 1 hour, copper fine powder was recovered. Then, after drying at 70 degreeC in nitrogen for 1 hour, it was crushed and the surface-treated copper fine particle was obtained. The paste was prepared by the procedure of Example 3, and the resistance of the fired body was measured.

(Example 9: Examples 33 to 35)
The copper fine particles of Examples 8, 14, and 24 were prepared by adjusting the paste in the procedure of Example 3 with a composition of 0.8% acrylic resin and the balance dihydroterpineol so that the metal ratio was 85%, and a fired body was obtained. It was.

(Example 10: Examples 36 to 38)
The paste was prepared by the procedure of Example 3 with the composition of the copper fine particles of Examples 8, 14, and 24 having a rosin of 0.8% and the balance of terpineol so that the metal ratio was 85%, and a fired body was obtained.

(Example 11: Comparative Example 1)
In a 1 L beaker, 50 g of cuprous oxide powder and 0.25 g of gum arabic as a protective agent (grain growth inhibitor) are dispersed in 350 mL of pure water, and 100 mL of dilute sulfuric acid with a volume ratio of 25% is added instantaneously thereto, A disproportionation reaction was performed. Decantation and water washing were repeated from this slurry to recover 20 g of copper fine particles having a D50 of 0.2 μm. The copper fine particles were mixed with 350 mL of a sodium hydroxide aqueous solution having a liquid temperature of 25 ° C. and pH 9.0 for 10 minutes, and the copper fine particles were separated by decantation. The copper fine particles and 100 mL of an aqueous solution containing 0.2 g of BTA were mixed for 30 minutes, and the copper fine particles were recovered by suction filtration. The copper fine particles crushed by the procedure of Example 3 were processed into a paste, and the resistance of the fired body was measured.

  These results are shown in Table 2 below.

However, symbols in the above table are as follows.
* A1; Diethanolamine-modified product A2; Dimethylamine-modified product A3; Bis (2-ethoxyethyl) amine-modified product A4; Dibenzylamine-modified product A5; Diphenylamine-modified product A6; Diallylamine-modified product ** Trp: Tryptophan, Asn; Asparagine Arg; Arginine, His; Histidine *** B1; Diethanolamine benzyl chloride modified B2; Dimethylamine benzyl chloride modified B3; Bis (2-ethoxyethyl) amine benzyl chloride modified B4; Dibenzylamine benzyl chloride modified B5 Modified diphenylamine benzyl chloride B6; modified diallylamine benzyl chloride

  In addition, “not measurable” in the above table indicates that the specific resistance was large beyond the measurement range.

  According to the present invention, surface-treated copper fine particles having excellent oxidation resistance and low-temperature sinterability can be obtained by a simple process. The present invention is industrially useful.

Claims (16)

Copper fine particles obtained by performing a chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor,
Surface-treated copper fine particles obtained by mixing with an aqueous solution containing 0.03 to 10% by weight of a nitrogen-containing organic substance with respect to the copper fine particles. After mixing copper fine particles obtained by performing chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor with dilute sulfuric acid,
Furthermore, the surface-treated copper fine particle obtained by mixing with the aqueous solution containing 0.03-10 weight% of nitrogen containing organic substance with respect to copper fine particle.   The surface-treated copper fine particles according to claim 1 or 2, wherein the aqueous solution containing a nitrogen-containing organic substance is an alkaline aqueous solution. Nitrogen-containing organic matter
An amino acid; or any of the following groups:
—CH (OH) —CH ₂ —NR ¹ R ² group (where R ¹ and R ² are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- It is a group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group and a C3 to C8 linear or branched alkenyl group. )
Or —CH (OH) —CH ₂ — [N ⁺ R ¹ R ² R ³ ] X ₁ ^— group (where R ¹ , R ² and R ³ are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- A group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group, a C3-C8 linear or branched alkenyl group,
X ₁ ⁻ is a monovalent anion selected from the group consisting of a halide ion and CH ₃ SO ₄ ^— )
The surface-treated copper fine particles according to any one of claims 1 to 3, which is an amine compound having one or more of the following. Nitrogen-containing organics have the following formula I:
(Where n is an integer of 1 to 8,
The R group is any of the following groups:
—NR ¹ R ² group (where R ¹ and R ² are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- It is a group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group and a C3 to C8 linear or branched alkenyl group. )
Or-[N ⁺ R ¹ R ² R ³ ] X ₁ ^- group (wherein R ¹ , R ² and R ³ are each independently
C1-C8 alkyl group, C1-C8 hydroxyalkyl group, C2-C8 alkoxyalkyl group, C7-C10 substituted or unsubstituted phenylalkyl group, C6-C8 substituted or unsubstituted phenyl group, C12- A group selected from the group consisting of a C16 substituted or unsubstituted naphthyl group, a C3-C8 linear or branched alkenyl group,
X ₁ ⁻ is a monovalent anion selected from the group consisting of halide ions and CH ₃ SO ₄ ^— ))
The surface-treated copper fine particle in any one of Claims 1-4 which is a nitrogen-containing organic substance represented by these.   The surface-treated copper fine particles according to any one of claims 1 to 5, wherein the grain growth inhibitor is at least one selected from natural resins, polysaccharides, and gelatin.   The surface-treated copper fine particles according to any one of claims 1 to 6, wherein the average particle size of the copper fine particles is in the range of 0.1 to 1.0 µm.   The surface-treated copper fine particle according to any one of claims 1 to 7, wherein the copper fine particle has a cuprous oxide layer on at least a part of the particle surface. A surface-treated copper fine particle according to any one of claims 1 to 8; and a copper fine particle paste comprising alcohol or glycol having a boiling point of 250 ° C or lower.   Furthermore, the copper fine particle paste of Claim 9 containing an acrylic resin or a rosin.   A fired body having a specific resistance of 50 μΩcm or less, obtained by firing the copper fine particle paste according to claim 9 or 10 at 350 ° C. or less in a non-oxidizing atmosphere. Copper fine particles obtained by performing a chemical reduction method or disproportionation reaction in the presence of a grain growth inhibitor,
A step of mixing with an aqueous solution containing 0.03 to 10% by weight of nitrogen-containing organic matter with respect to the copper fine particles,
A method for producing surface-treated copper fine particles. A step of mixing copper fine particles obtained by performing a chemical reduction method or a disproportionation reaction in the presence of a grain growth inhibitor with dilute sulfuric acid to obtain dilute sulfuric acid-treated copper fine particles,
Mixing the dilute sulfuric acid-treated copper fine particles with an aqueous solution containing 0.03 to 10% by weight of nitrogen-containing organic matter with respect to the copper fine particles,
A method for producing surface-treated copper fine particles. Mixing the surface-treated copper fine particles produced by the method according to claim 12 or 13 with an alcohol or glycol having a boiling point of 250 ° C. or lower to obtain a copper fine particle paste;
A method for producing a copper fine particle paste. Mixing the surface-treated copper fine particles produced by the method according to claim 12 or 13 with an alcohol or glycol having a boiling point of 250 ° C. or lower, an acrylic resin, or rosin to obtain a copper fine particle paste;
A method for producing a copper fine particle paste. A step of firing the copper fine particle paste produced by the method according to claim 14 or 15 at 350 ° C. or less in a non-oxidizing atmosphere to obtain a fired body,
A method for producing a fired body.