CN116652203A - Preparation method of superfine silver powder - Google Patents

Abstract

The present invention relates to a preparation method of superfine silver powder, which comprises the following steps: (1) dissolving silver nitrate in deionized water to obtain a metal salt solution, and keeping the temperature at 30-50°C; (2) dissolving reducing agent in deionized water , and add a pH regulator to obtain a reducing agent solution, and keep the temperature at 30-50°C; (3) dissolve the dispersant and dopant in deionized water to obtain a mixed solution, and keep the temperature at 30-50°C; (4) mix the Add the solution to the metal salt solution, stir for 1 min, add the reducing agent solution to the metal salt solution, and stir to react to obtain silver powder; (5) Wash the silver powder until the conductivity of the lotion is ≤10 μs , solid-liquid separation, to obtain Ag powder filter cake; (6) add surface coating agent-absolute ethanol solution in the Ag powder filter cake, stir evenly, through drying, air flow dispersion, sieving, obtain particle diameter 0.4～0.8 μm ultrafine silver powder. The invention has the advantages of simple operation, low cost and easy realization of industrialized production, and the obtained silver powder product has small particle size, narrow distribution and good dispersibility.

Description

A kind of preparation method of superfine silver powder

technical field

The invention relates to the technical field of preparation of precious metal materials, in particular to a preparation method of ultrafine silver powder.

Background technique

With the continuous development of economic globalization, the research and development of electronic materials has also experienced unprecedented development. Conductive paste is a very important branch of electronic materials, among which conductive silver paste has attracted much attention due to its many excellent properties. As a functional material with high surface activity and excellent electrical conductivity, ultra-fine silver powder is widely used in the fields of conductive paste, energy industry, composite materials, catalysts, and antibacterial materials. Silver powder is the most important raw material of conductive paste, which has an important influence on parameters such as film formation, film thickness, electrical properties, solderability and adhesion during the preparation process. The quality of silver powder directly affects the conductive paste and the final formation of conductors. performance.

At present, there are many methods for preparing silver powder at home and abroad, mainly including grinding method, atomization method, evaporation condensation method, electrochemical deposition method, sol-gel method, liquid phase reduction method and so on. Among them, the liquid phase reduction method has simple operation process, small investment, high output, less loss and good performance, so it has become one of the most promising preparation methods at present. However, the current silver powder prepared by the liquid phase reduction method has problems such as wide particle size distribution, easy agglomeration of silver powder particles, and difficulty in washing and settling.

Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of superfine silver powder with simple operation, low cost and easy industrial production.

In order to solve the above problems, a kind of preparation method of superfine silver powder of the present invention comprises the following steps:

(1) Dissolve silver nitrate in deionized water to obtain a metal salt solution, and keep the temperature at 30~50°C;

(2) Dissolve the reducing agent in deionized water, and add a pH regulator to obtain a reducing agent solution, and keep the temperature at 30~50°C;

(3) Dissolve the dispersant and dopant in deionized water to obtain a mixed solution, and keep the temperature at 30~50°C;

(4) adding the mixed solution into the metal salt solution, stirring for 1 min, adding the reducing agent solution into the metal salt solution, stirring and reacting to obtain silver powder;

(5) When the silver powder is washed until the conductivity of the lotion is less than or equal to 10 μs, the solid and liquid are separated to obtain the Ag powder filter cake;

(6) Add a surface coating agent-absolute ethanol solution to the Ag powder filter cake, stir evenly, dry, air-flow disperse, and sieve to obtain ultrafine silver powder with a particle size of 0.4-0.8 μm.

The content of silver nitrate in described step (1) metal salt solution is 150～250g//L.

The content of the reducing agent in the step (2) reducing solution is 100-200g/L; the reducing agent is any one of glucose, ascorbic acid, hydroquinone, hydrazine hydrate, formaldehyde, and organic amine.

In the step (2), the content of the pH regulator in the reducing agent solution is 10-100 g/L; the pH regulator is one of sodium hydroxide, ammonia water, and ethylenediamine.

The content of dispersant in described step (3) mixed solution is 20～100g/L; Described dispersant is a kind of in polyvinylpyrrolidone, polyethylene glycol, polyvinylamide, gelatin.

The content of the dopant in the step (3) mixed solution is 0.1 ~ 1.0g/L; the dopant is one of copper nitrate, sodium nitrate, potassium sulfate and copper sulfate.

The adding and stirring conditions of the reducing agent solution in the step (4) refer to the adding speed of 10 L/min, the adding time of 2 min, the reaction time of 4-20 min, and the stirring frequency of 40 Hz.

The mass concentration of surface coating agent-dehydrated ethanol solution in the described step (6) is 0.1～10g/L; Wherein the surface coating agent is a kind of in palmitic acid, stearic acid, erucic acid, and its addition is silver powder 0.1%~0.5% of the mass.

The drying conditions in the step (6) refer to a temperature of 60-70° C. and a time of 15-20 hours.

Compared with the prior art, the present invention has the following advantages:

1. The present invention firstly adds dispersant and dopant mixed solution in metal salt solution, then adds reducing agent solution at a certain flow rate, and prepares silver powder by controlling reaction system temperature and liquid addition speed; and by controlling dopant adding The amount and temperature of the reaction system control the amount of silver powder nucleation at the initial stage of the reaction, and the speed of adding liquid is controlled to control the growth rate of silver powder to achieve the purpose of obtaining silver powder products with small particle size, narrow distribution and good dispersibility.

2. The present invention uses the liquid phase reduction method to scientifically and rationally control the reducing agent, dispersant, dopant, etc. during the reduction process, thereby obtaining ultrafine silver powder with small particle size and good dispersibility.

3. The invention has simple operation, wide sources of raw materials, low cost, low requirements on equipment, and easy realization of industrialized production.

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is the ultrafine silver powder electron micrograph of embodiment 1 of the present invention.

FIG. 2 is an electron micrograph of the ultrafine silver powder of Example 2 of the present invention.

FIG. 3 is an electron micrograph of the ultrafine silver powder of Example 3 of the present invention.

FIG. 4 is an electron micrograph of the ultrafine silver powder of Example 4 of the present invention.

Detailed ways

A preparation method of superfine silver powder, comprising the following steps:

(1) Dissolve silver nitrate in deionized water to obtain a metal salt solution with a silver nitrate content of 150-250g//L, and keep the temperature at 30-50°C.

(2) Dissolve the reducing agent in deionized water, and add a pH regulator to obtain a reducing agent solution, and keep the temperature at 30-50°C. Among them: the content of reducing agent in the reducing solution is 100~200g/L, and the reducing agent is any one of glucose, ascorbic acid, hydroquinone, hydrazine hydrate, formaldehyde, and organic amine; the content of pH regulator is 10~100g /L, the pH adjuster is one of sodium hydroxide, ammonia water, and ethylenediamine.

(3) Dissolve the dispersant and dopant in deionized water to obtain a mixed solution, and keep the temperature at 30~50°C. Among them: the content of dispersant in the mixed solution is 20~100g/L, and the dispersant is one of polyvinylpyrrolidone, polyethylene glycol, polyvinylamide, and gelatin; the content of dopant is 0.1~1.0g/L The dopant is one of copper nitrate, sodium nitrate, potassium sulfate and copper sulfate.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 4-20 minutes to obtain silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

⑹ Add a surface coating agent-absolute ethanol solution with a mass concentration of 0.1~10g/L to the Ag powder filter cake. The surface coating agent is one of palmitic acid, stearic acid, and erucic acid. 0.1%~0.5% of the mass. Then stir evenly, dry at 60~70°C for 15~20h, and then disperse and sieve by airflow to obtain ultrafine silver powder with a particle size of 0.4~0.8μm.

Embodiment 1 A kind of preparation method of superfine silver powder, comprises the following steps:

(1) Dissolve 250g of silver nitrate in 1L of deionized water to obtain a metal salt solution, and keep the temperature at 35°C.

(2) Dissolve 200g of ascorbic acid in 1L of deionized water, then add 45g of ethylenediamine to obtain a reducing agent solution, and keep the temperature at 35°C.

(3) Dissolve 20g of polyvinylpyrrolidone and 0.2g of copper nitrate in 0.2L of deionized water to obtain a mixed solution, and keep the temperature at 35°C.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 10 minutes to obtain 152.6 g of silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

⑹Add surface coating agent-absolute ethanol solution with a mass concentration of 8g/L [modified] to the Ag powder filter cake. Surface coating agent-absolute ethanol solution refers to dissolving 0.8g erucic acid in 0.1L absolute ethanol The resulting solution. Then stir evenly, dry at 65°C for 20 hours, and then disperse and sieve by airflow to obtain superfine silver powder with an average particle size of 0.66μm.

Embodiment 2 A kind of preparation method of superfine silver powder, comprises the following steps:

(1) The metal salt solution is the same as in Example 1.

(2) Dissolve 180g of glucose in 1L of deionized water, and add 100g of ammonia water to obtain a reducing agent solution, and keep the temperature at 35°C.

(3) Dissolve 20g of polyvinylpyrrolidone and 0.1g of copper nitrate in 0.2L of deionized water to obtain a mixed solution, and keep the temperature at 35°C.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 10 minutes to obtain 138.3 g of silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

(6) Add a surface coating agent-absolute ethanol solution with a mass concentration of 0.32g/L to the Ag powder filter cake. solution. Then stir evenly, dry at 65°C for 20 hours, and then disperse and sieve by air flow to obtain ultrafine silver powder with a particle size of 0.42 μm.

Embodiment 3 A kind of preparation method of superfine silver powder, comprises the following steps:

(1) Dissolve 150g of silver nitrate in 1L of deionized water to obtain a metal salt solution, and keep the temperature at 35°C.

(2) Dissolve 115g of formaldehyde and 10g of sodium hydroxide in 1L of deionized water, and keep the temperature at 35°C.

(3) The mixed solution is the same as in Example 1.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 10 minutes to obtain 151.9 g of silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

(6) Add a surface coating agent-absolute ethanol solution with a mass concentration of 0.16 g/L to the Ag powder filter cake, and the surface coating agent-absolute ethanol solution is the same as in Example 2. Then stir evenly, dry at 65°C for 20 hours, and then disperse and sieve by air flow to obtain ultrafine silver powder with a particle size of 0.54 μm.

Embodiment 4 A kind of preparation method of superfine silver powder, comprises the following steps:

(1) The metal salt solution is the same as in Example 1.

(2) Dissolve 180g of hydrazine hydrate in 1L and 80g of ammonia water in 1L of deionized water to obtain a reducing agent solution, and keep the temperature at 30°C.

(3) Dissolve 30g of gelatin and 0.1g of copper sulfate in 0.5L of deionized water to obtain a mixed solution, and keep the temperature at 30°C.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 4 minutes to obtain 148.7 g of silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

(6) Add a surface coating agent-absolute ethanol solution with a mass concentration of 0.16 g/L to the Ag powder filter cake, and the surface coating agent-absolute ethanol solution is the same as in Example 2. Then stir evenly, dry at 60°C for 20 hours, and then disperse and sieve by airflow to obtain ultrafine silver powder with a particle size of 0.44μm.

Electron microscope scanning is carried out to the superfine silver powder that above-mentioned embodiment 1-4 gains, as shown in Figure 1～4. It can be found from the figure that the particle size of the silver powder is small and evenly distributed, and the dispersibility is good.

Embodiment 5 A kind of preparation method of superfine silver powder, comprises the following steps:

(1) Dissolve 200g of silver nitrate in 1L of deionized water to obtain a metal salt solution, and keep the temperature at 35°C.

(2) Dissolve 150g of hydroquinone and 100g of ammonia water in 1L of deionized water to obtain a reducing agent solution, and keep the temperature at 35°C.

(3) Dissolve 40g of polyethylene glycol and 0.1g of sodium nitrate in 0.6L of deionized water to obtain a mixed solution, and keep the temperature at 35°C.

(4) Add the mixed solution to the metal salt solution, stir for 1 min, then add the reducing agent solution to the metal salt solution at a rate of 10 L/min, and the adding time is 2 min. Stir and react at a frequency of 40 Hz for 10 min to obtain 123.9 g of silver powder.

(5) Wash the silver powder until the conductivity of the lotion is less than or equal to 10 μs, then separate the solid and liquid to obtain the Ag powder filter cake.

(6) Add a surface coating agent-dehydrated ethanol solution with a mass concentration of 4g/L to the Ag powder filter cake. The surface coating agent-dehydrated ethanol solution refers to the solution obtained by dissolving 0.4g stearic acid in 0.1L dehydrated ethanol . Then stir evenly, dry at 60°C for 20 hours, and then disperse and sieve by airflow to obtain ultrafine silver powder with a particle size of 0.77μm.

Claims (9)

1. a preparation method of superfine silver powder, comprising the following steps: (1) Dissolve silver nitrate in deionized water to obtain a metal salt solution, and keep the temperature at 30~50°C; (2) Dissolve the reducing agent in deionized water, and add a pH regulator to obtain a reducing agent solution, and keep the temperature at 30~50°C; (3) Dissolve the dispersant and dopant in deionized water to obtain a mixed solution, and keep the temperature at 30~50°C; (4) adding the mixed solution into the metal salt solution, stirring for 1 min, adding the reducing agent solution into the metal salt solution, stirring and reacting to obtain silver powder; (5) When the silver powder is washed until the conductivity of the lotion is less than or equal to 10 μs, the solid and liquid are separated to obtain the Ag powder filter cake; (6) Add a surface coating agent-absolute ethanol solution to the Ag powder filter cake, stir evenly, dry, air-flow disperse, and sieve to obtain ultrafine silver powder with a particle size of 0.4-0.8 μm. 2. the preparation method of a kind of ultrafine silver powder as claimed in claim 1 is characterized in that: the content of silver nitrate in the described step (1) metal salt solution is 150～250g//L. 3. the preparation method of a kind of superfine silver powder as claimed in claim 1 is characterized in that: the content of reducing agent in described step (2) reducing solution is 100～200g/L; Described reducing agent is glucose, ascorbic acid, paraben Any one of hydroquinone, hydrazine hydrate, formaldehyde, and organic amines. 4. the preparation method of a kind of superfine silver powder as claimed in claim 1, is characterized in that: the content of pH regulator in described step (2) reductant solution is 10～100g/L; Described pH regulator is hydrogen oxide One of sodium, ammonia, and ethylenediamine. 5. the preparation method of a kind of superfine silver powder as claimed in claim 1 is characterized in that: the content of dispersant in described step (3) mixed solution is 20～100g/L; Described dispersant is polyvinylpyrrolidone, polyvinylpyrrolidone One of ethylene glycol, polyvinylamide, and gelatin. 6. the preparation method of a kind of ultrafine silver powder as claimed in claim 1 is characterized in that: the content of dopant in described step (3) mixed solution is 0.1～1.0g/L; Described dopant is copper nitrate , sodium nitrate, potassium sulfate and copper sulfate. 7. the preparation method of a kind of ultra-fine silver powder as claimed in claim 1 is characterized in that: the liquid addition and stirring condition of reducing agent solution in the described step (4) refers to that the liquid addition speed is 10L/min, and the liquid addition time is 2min , the reaction time is 4~20min, and the stirring frequency is 40Hz. 8. The preparation method of a kind of superfine silver powder as claimed in claim 1, is characterized in that: the mass concentration of surface coating agent-dehydrated alcohol solution is 0.1～10g/L in the described step (6); wherein surface coating The agent is one of palmitic acid, stearic acid and erucic acid, and its addition amount is 0.1%~0.5% of the silver powder mass. 9. The method for preparing ultra-fine silver powder according to claim 1, characterized in that: the drying conditions in the step (6) refer to a temperature of 60-70°C and a time of 15-20 hours.