KR101109117B1 - Preparing method of copper powder - Google Patents

Abstract

The present invention relates to a method for producing a copper powder, and more particularly, to a method for producing a copper powder using aliphatic aldehyde as a reducing agent after adding sodium hydroxide to an aqueous copper sulfate solution to form a copper hydroxide precipitate.

Unlike the conventional manufacturing method of reducing at a high temperature of 180 ~ 200 ℃ or more of the present invention, the production of copper powder is possible by automatic reduction reaction at room temperature, and the reduction time can be greatly reduced, thereby greatly improving productivity. You can. In addition, in the process of preparing a copper powder, it is possible to produce a copper powder without an intermediate hydrazine-copper complex compound or a nitric acid as a copper ion nucleating agent, and does not require a surfactant and an organic solvent.

Copper sulfate pentahydrate, formaldehyde,

Description

Manufacturing method of copper powder

The present invention relates to a method for producing a copper powder without using a surfactant and an organic solvent. Specifically, at room temperature, sodium hydroxide is added to an aqueous copper sulfate solution to prepare a copper hydroxide precipitate, and then aliphatic aldehyde is used as a reducing agent. It relates to a method for producing a copper powder.

Research on the preparation of copper powder has been performed for a long time, and gas spraying, evaporation / condensation, pyrolysis, wet reduction, micro-emulsion, hydrothermal synthesis, sol-gel, etc. Various methods are known.

Gas atomization is a method of producing fine particles by injecting a high pressure inert gas with a metal melt from a nozzle and is suitable for mass production, but is not used for large scale processes due to low recovery rate and inert atmosphere. Thermal decomposition method is a method of producing metal powder by thermal decomposition with a metal compound precursor and a gas reducing agent, which can produce fine metal particles, but due to the fusion and aggregation between particles during the heat treatment process, a separate classification process and a crushing process are performed. It is necessary and the recovery rate falls a lot by the manufacturing method of the metal powder for thick film materials (Unexamined-Japanese-Patent No. 2002-259003). The gas evaporation method is a method of preparing fine metal powder by heating and evaporating a metal precursor compound in an inert gas such as helium or argon or an active gas such as methane or ammonia and condensing the vaporized vapor in the gas again. It is an advantageous method for the production of metal powder with an average particle diameter of 1 μm or less, but has a disadvantage in that the production cost of the metal powder is very small because the production amount is extremely small. Compared to the gas phase reduction method described above, the shape control of the powder is easier, and the liquid phase reduction method, which is easy to prepare fine metal powders from submicron to micron units, is suitable for dissolving metal salts, reducing metal ions, and depositing metal particles. Proceeds from the state.

Copper powder production methods known to date can be classified as follows. ① Disperse copper hydroxide, copper oxide, and copper carbonate compounds in polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol), sulfur compound aqueous solution, distilled water, and reduce copper compounds with surfactants, complexing agents, and reducing agents. Method of preparing copper particles (PCT WO 2006/1944), ② Method of preparing copper powder by the same reduction process as ① by adding a reduction reaction accelerator (2 or more carboxyl compounds), Ag salt or Pd salt (Japan) Korean Patent Publication No. 2005-307335) and ③ a method of preparing fine copper particles by dissolving a water-soluble copper compound in distilled water, adding an alkali metal hydroxide or an alkaline earth metal hydroxide to generate a precipitate with copper hydroxide, and reducing it with a surfactant and a reducing agent ( Japanese Unexamined Patent Publication No. 2000-268630, Korean Unexamined Patent Publication No. 10-486604, and Korean Unexamined Patent Publication No. 10-3169) There ryeojyeo.

Commonly used parts for the production of copper particles by wet reduction include (1) copper compounds as copper oxide (if a polyol compound is used as the organic solvent), copper hydroxide, copper chloride, copper sulfate, and copper carbonate (distilled water is used as the solvent). (Polyvinyl alcohol), PVP (polyivnylpyrrolidone), PEI (polyethylene imine), gelatin (gelatin), dextrin, albumin (albumin) as a surfactant, and hydrazine (reducing agent) as a surfactant. hydrazine) and hydrazine hydrate are used. The conventional method for producing copper by wet reduction is advantageous in that a relatively low reduction temperature (except when polyol is used as an organic solvent), nano and micro size copper particles production, and a short reduction time are advantageous. In addition, a copper oxide compound, which is a relatively inexpensive copper compound, is used as a raw material for producing copper powder. However, the drawbacks of the copper powder production method currently used are (1) Ag and Pd ions, which are used as nucleating agents, are included in the produced copper particles, so that the purity is low. Due to its solubility, mass production is restricted and high temperature reduction temperature (180-200 ℃) is required. ③ Hydrazine compounds (hydrazine, hydrazine hydrate, hydrazine aqueous solution, hydrazine sulfate, hydrazine dihydrochloride) used as reducing agents show strong reducing power but similar Since it is 5 to 50 times more expensive than formaldehyde showing a reducing potential, there is a problem in that the advantage of using copper oxide as a raw material is lost, as well as a high respiratory toxicity (carcinogenicity).

There is a need for a method for producing copper powder for use of inexpensive reducing agents under these atmospheres, elimination of organic solvents, and avoidance of high temperature reduction conditions (when polyol or fatty acid esters are used as the organic solvent).

Accordingly, the present inventors have relatively little adverse effect on the human body, and have tried to prepare copper powder using an inexpensive reducing agent and without using a surfactant and an organic solvent, and as a result, through an automatic reduction reaction using an aliphatic aldehyde as a reducing agent. The present invention has been completed by knowing that copper powder can be produced at a short reduction time at room temperature without the use of surfactants, organic solvents and copper ion nucleating agents at room temperature. That is, an object of the present invention is to provide a new copper powder manufacturing method, to provide a copper powder excellent in productivity and economy.

The present invention for solving the above problems is the first step of preparing a precipitate of copper hydroxide by adding sodium hydroxide to an aqueous copper sulfate solution; And a second step of preparing precipitated copper powder by adding an aliphatic aldehyde which is a reducing agent. In addition, the first step and the second step is characterized in that proceeds at a temperature condition of 10 ~ 35 ℃.

Such a method of preparing the copper powder of the present invention does not require a heating reduction operation (more than 180 ° C.) or an expensive hydrazine compound, which is essential when the organic solvent is used as a reducing solvent of the copper compound, as well as using an inexpensive reducing agent. Since the reduction time can be significantly reduced, it is possible to provide a high productivity copper powder production method.

Such a method for producing a copper powder of the present invention will be described in detail.

The copper powder production method of the present invention comprises the first step of preparing a copper hydroxide precipitate by adding sodium hydroxide to the copper sulfate aqueous solution; And a second step of preparing precipitated copper powder by adding an aliphatic aldehyde which is a reducing agent.

In addition, the manufacturing method of the present invention may further include a third step of filtering, washing and drying the precipitated copper powder in addition to the two steps.

And the first step to the third step can be carried out at 10 ~ 35 ℃, more preferably 15 ~ 30 ℃ room temperature is characterized by that.

In the first step, the copper sulfate aqueous solution is prepared by dissolving copper sulfate in distilled water, more preferably crystalline copper sulfate pentahydrate, wherein the weight ratio of copper sulfate to distilled water is 1: 2 to 1: 8, more preferably 1: 3 to 1: 5 weight ratio is suitable. This weight ratio is determined from the solubility of copper sulfate in the temperature range of 20 ° C. to 30 ° C., and if it is outside the above range, coarse copper particles are produced or the amount of copper powder produced is reduced by rapid reduction of copper ions. This lowers industrial applicability. In addition, since the amount of distilled water required to dissolve the copper sulfate may increase when it is out of the thermodynamically determined solubility range, it is best to use distilled water and crystalline copper sulfate pentahydrate within the above range.

The sodium hydroxide added for copper hydroxide precipitation is preferably 0.35 to 0.65 weight ratio, more preferably 0.4 to 0.5 weight ratio, based on 1 weight ratio of copper sulfate. In this case, when sodium hydroxide is used in an amount less than 0.35 with respect to 1 weight ratio of copper sulfate, sodium hydroxide may not be precipitated, but may be present in a dissolved state in distilled water. Due to this may have an effect on the reduction reaction, it is preferable that the mixing ratio of sodium hydroxide does not deviate from the above conditions.

In the second step, the aliphatic aldehyde used as a reducing agent of copper ions shows an excellent reducing power with respect to the copper hydroxide produced by the addition of sodium hydroxide in the aqueous copper sulfate solution, the weight of the aliphatic aldehyde added to reduce the copper hydroxide is 1 weight ratio of the copper sulfate It is preferable to add 0.1 to 0.4 weight ratio with respect to, more preferably 1: 0.12 to 0.3 weight ratio, which weight ratio is determined from the stoichiometry of copper hydroxide or copper oxide and aliphatic aldehyde, to induce a reduction reaction to a minimum. It is preferable to use aliphatic aldehyde within the range of reducing agent concentration and the range of congestion of experimentally determined reduction reaction. And preferably, the aliphatic aldehyde is preferably used one selected from formaldehyde, acetaldehyde, propionaldehyde, butyl aldehyde, most preferably using formaldehyde. Through this reaction, the copper reduction reaction in the second step is completed in approximately 10 seconds to 20 minutes.

After the completion of the reduction reaction of the second step, the copper particles are generated and settled to the bottom, the supernatant is discarded and washed and dried with filtration and distilled water at room temperature to obtain a copper powder, the filtration, washing and drying is General methods used in the can be used and are not particularly limited. In addition, when the washing is incomplete, a green-yellow precipitate may be formed on the surface of the copper particles, and thus the washing should be performed completely.

The present invention as described above will be described in more detail based on the following examples. However, the scope of the present invention is not limited by the following examples.

Example 1 Preparation of Copper Powder

4.5 g of crystalline copper sulfate pentahydrate was completely dissolved in 27 g of distilled water at room temperature (23-27 ° C) to obtain an aqueous copper sulfate solution, and 1.7 g of sodium hydroxide was added to the copper sulfate aqueous solution and stirred. After the addition of sodium hydroxide, a dark blue copper hydroxide precipitate was formed, and the formation of copper hydroxide precipitate was confirmed by XRD diffraction analysis. The results are shown in FIG. 1. 1.46 g of aqueous formaldehyde solution (37% by weight) in which 0.54 g of formaldehyde as a reducing agent was dissolved in an aqueous solution in which the copper hydroxide precipitate was formed was added at room temperature. Reduction of the precipitate after the addition of aqueous formaldehyde solution proceeded rapidly (two steps reduction time: 3 minutes 17 seconds), resulting in a dark red copper powder. Thereafter, the copper powder was recovered from the reaction mother liquor with GF / C filter paper having a pore size of about 1.3 mu m. Next, the recovered copper powder was washed with distilled water at 24 to 25 ° C and dried at 100 ° C to obtain 0.8 g of copper powder (yield 70%). The XRD diffraction diagram of the copper powder fished in FIG. 2 is shown.

Example 2

3.1 g of crystalline copper sulfate pentahydrate was completely dissolved in 9.3 g of distilled water at room temperature (23 to 27 ° C) to obtain an aqueous copper sulfate solution, and then 1.21 g of sodium hydroxide was added and stirred. After addition of sodium hydroxide, a dark blue copper hydroxide precipitate was formed, and 1 g of aqueous formaldehyde solution (37%) in which 0.37 g of formaldehyde, a reducing agent was dissolved, was added at room temperature. Reduction of the precipitate proceeded rapidly after addition of aqueous formaldehyde solution (two steps reduction time: 6 minutes 42 seconds), resulting in a dark red copper powder. Thereafter, the copper powder was recovered from the reaction mother liquor with GF / C filter paper having a pore size of about 1.3 mu m. Next, the recovered copper powder was washed with distilled water at 24 to 25 ° C and dried at 100 ° C to obtain 0.65 g of copper powder (yield 83%). And, the XRD diffraction diagram of the copper powder produced in Figure 3 is shown.

Example 3

In the same manner as in Example 1, using 2 g of sodium hydroxide to produce a copper hydroxide precipitate, to obtain a copper powder 1 g (2 steps reduction time: 2 minutes 12 seconds, yield 88.9%)

Example 4

1.05 g of copper powder was obtained using an aqueous copper sulfate solution prepared in the same manner as in Example 1 except that 4.5 g of crystalline copper sulfate pentahydrate was completely dissolved in 15 g of distilled water. (2 step reduction time: 1 minute 35 seconds, Yield 93.3%)

Example 5

 In the same manner as in Example 1, 1.91 g of a formaldehyde aqueous solution (37%) was used, and 0.77 g of copper powder was obtained (stage 2 reduction time: 3 minutes 10 seconds, yield 67.4%).

Example 6

 In the same manner as in Example 1, 0.84 g of acetaldehyde was used instead of the aqueous formaldehyde solution (37%), and 0.51 g of copper powder was obtained (two steps reduction time: 13 minutes 1 second, yield 43.75%).

Example 7

In the same manner as in Example 1, 1.2 g of propionaldehyde was used, and 0.46 g of copper powder was obtained (two step reduction time: 14 minutes and 26 seconds, yield 40.25%).

Example 8

In the same manner as in Example 1, 1.3 g of butylaldehyde aqueous solution was used, and 0.24 g of copper powder was obtained (two-step reduction time: 18 minutes 35 seconds, yield 21%).

Through the above examples, it can be seen that the present invention can produce copper powder in high yield without requiring a high reduction temperature, a surfactant, and an organic solvent.

Copper powder produced by the highly productive manufacturing method of the present invention is a circuit forming material of a printed wiring board, various electrical contact material, external electrode materials such as capacitors, internal electrodes of a multilayer ceramic capacitor (MLCC), It may be widely used in plasma display panels (PDPs), field emission displays (FEDs), automobile heating wires, and the like.

1 is an XRD diffraction curve of copper hydroxide according to Example 1. FIG.

2 is an XRD diffraction curve of the copper powder prepared in Example 1. FIG.

3 is an XRD diffraction curve of the copper powder prepared in Example 2. FIG.

Claims (7)

A first step of preparing a copper hydroxide precipitate by adding sodium hydroxide to an aqueous copper sulfate solution; And A second step of preparing precipitated copper powder by adding aliphatic aldehyde as a reducing agent; The first step and the second step is a method of producing a copper powder, characterized in that proceeds under a temperature of 10 ~ 35 ℃. delete The method of claim 1, wherein the aliphatic aldehyde is selected from an aqueous formaldehyde solution, acetaldehyde, propionaldehyde, and butylaldehyde. The method of claim 1, wherein the copper sulfate aqueous solution comprises copper sulfate and distilled water in a weight ratio of 1: 2 to 1: 8. The method of claim 1, wherein the copper sulfate aqueous solution contains copper sulfate and distilled water, and the sodium hydroxide is 0.35 to 0.65 weight ratio with respect to 1 weight ratio of the copper sulfate. The method of claim 1, wherein the copper sulfate aqueous solution contains copper sulfate and distilled water, and the aliphatic aldehyde is 0.1 to 0.4 weight ratio based on 1 weight ratio of copper sulfate. The copper sulfate of any one of claims 4 to 6, wherein the copper sulfate It is a crystalline copper sulfate pentahydrate, The manufacturing method of the copper powder characterized by the above-mentioned.

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