Nano-silver particles for electronic 3D printing conductive ink and preparation method of nano-silver particles

Abstract

The invention discloses a preparation method of nano-silver particles for electronic 3D printing conductive ink, which comprises the following steps: carrying out surface ligand exchange by using diethanol amine, and carrying out surface modification on the nano-silver particles protected by a dispersing agent; the particle size of the nano-silver particles prepared through the method ranges from 20 nm to 80 nm, the particle size distribution of the particles is uniform, and the morphology of the nano-silver particles is similar to a sphere. The diethanol amine and the dispersing agent attached to the surfaces of the nano-silver particles are adopted for surface ligand exchange, the dispersing agent is effectively removed, the nano-silver particles with the sphere-like morphology are obtained, the subsequent complex washing procedure is not needed, the conductivity of the nano-silver particles is effectively guaranteed, the reaction is mild, operation is easy, and the preparation method is suitable for industrial production. The method is suitable for the field of electronic 3D printing conductive ink.

Description

Technical Field

[0001] The present invention relates to the technical field of nano silver powder preparation, and in particular to nano silver particles used for electronic 3D printing conductive ink and a preparation method thereof. Background Art

[0002] Electronic 3D printing refers to the technology of using high-precision 3D printing technology (such as piezoelectric inkjet printing, aerosol jet printing, electrofluid printing, etc.) to prepare electronic engineering devices from electronic conductive materials. It has shown great application prospects in the fields of information technology, energy storage, flexible wearables, medical treatment, aerospace, military industry, etc., and is crucial to supporting the transformation and upgrading of traditional industries. Electronic 3D printing technology can construct material microstructures in situ and realize the regulation of structures at the microscale, which has important exploratory significance for the development of high-performance electronic engineering devices.

[0003] Conductive ink is the core material of electronic 3D printing technology and one of the keys to the development of electronic 3D printing technology. Nanometal materials have become popular conductive ink functional materials due to their excellent electrical properties, and nanosilver materials have important research significance and application prospects due to their excellent conductivity, stable antioxidant ability and relatively low manufacturing cost.

[0004] The silver nanoparticles used to prepare conductive inks must meet the requirements of small particle size (<100nm), good chemical stability, and strong dispersibility to ensure that the conductive ink has good conductive properties and printing quality. Liquid phase chemical reduction is a common method for preparing silver nanoparticles, which can achieve stable preparation of small particle size (<100nm) particles. During the preparation process, a protective agent (such as polyvinyl pyrrolidone, PVP) is usually added to achieve uniform dispersion of silver nanoparticles. However, PVP is difficult to remove from the surface of silver nanoparticles. It usually requires high-speed oscillation, heating, pH adjustment and other methods to wash multiple times to partially remove it. This will greatly affect the conductivity of silver nanoparticles and limit their application in conductive inks. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing nanosilver particles for electronic 3D printing conductive ink in view of the above-mentioned deficiencies of the prior art. The method uses diethanolamine to exchange surface ligands with a dispersant attached to the surface of the nanosilver particles, effectively removes the dispersant, obtains nanosilver particles with a spherical morphology, and does not require subsequent complex washing steps, effectively ensures the conductive properties of the nanosilver particles, has a mild reaction, and is simple to operate, solving the problem that the existing high-speed oscillation, heating, pH adjustment and other methods of washing affect the conductivity of the nanosilver particles.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing nanosilver particles for electronic 3D printing conductive ink, characterized in that diethanolamine is used for surface ligand exchange, and the nanosilver particles protected by the dispersant are surface modified to prepare nanosilver particles for electronic 3D printing conductive ink.

[0007] The above-mentioned method for preparing nano silver particles for electronic 3D printing conductive ink is characterized in that the nano silver particles are prepared by liquid phase chemical reduction method, and the specific process includes the following steps:

[0008] Step 1, dissolving silver nitrate in deionized water to obtain a silver nitrate aqueous solution, and then adding acetonitrile to the silver nitrate aqueous solution to obtain a silver solution;

[0009] Step 2: dissolving a dispersant and a reducing agent in deionized water to obtain a dispersant solution and a reducing agent solution;

[0010] Step 3, the silver solution obtained in step 1 and the dispersant solution obtained in step 2 are mixed and stirred evenly, then the temperature is raised to the reaction temperature, and the reducing agent solution obtained in step 2 is added dropwise at the reaction temperature to react, and after the addition is completed, the reaction system is continued to react at room temperature to obtain a nano silver particle solution;

[0011] Step 4: centrifugally concentrate the nanosilver particle solution obtained in step 3, and then wash it with deionized water to obtain a nanosilver concentrate;

[0012] Step 5: Disperse the nanosilver concentrate obtained in step 4 in deionized water, then add diethanolamine and stir to react, wash with deionized water after centrifugal concentration, repeat the dispersion, stirring reaction, centrifugal concentration and washing process, and finally wash with anhydrous ethanol to obtain nanosilver particles for electronic 3D printing conductive ink after concentration.

[0013] The above-mentioned method for preparing nano silver particles for electronic 3D printing conductive ink is characterized in that the concentration of the silver nitrate aqueous solution in step 1 is 0.1 mol·L -1 The volume ratio of water to acetonitrile in the silver solution is 1:0.5 to 2. By controlling the volume ratio of water to acetonitrile in the silver solution, the concentration of the silver solution system is regulated, thereby controlling the subsequent reaction rate.

[0014] The above-mentioned method for preparing nanosilver particles for electronic 3D printing conductive ink is characterized in that the dispersant in step 2 is polyvinyl pyrrolidone PVP or hexadecyltrimethylammonium bromide CTAB, and the molecular weight of polyvinyl pyrrolidone PVP is 40,000.

[0015] The above-mentioned method for preparing nanosilver particles for electronic 3D printing conductive ink is characterized in that the reducing agent in step 2 is ascorbic acid, hydrazine hydrate, sodium borohydride, ferrous sulfate or sodium sulfite.

[0016] The above-mentioned method for preparing nanosilver particles for electronic 3D printing conductive ink is characterized in that the stirring speed in step 3 is 300rpm to 600rpm; the dropwise addition is carried out using a dropping funnel, and the dropping speed is controlled so that the dropping time is not less than 20min; the reaction temperature is 0 to 50°C, the room temperature is 10°C to 25°C, and the reaction time at room temperature is not less than 40min. By controlling the dropping speed and reaction temperature and continuing the reaction time, the reaction speed is controlled to ensure complete reaction.

[0017] The above-mentioned method for preparing nanosilver particles for electronic 3D printing conductive ink is characterized in that the rotation speed of the centrifugal concentration in step 4 and step 5 is 10000rpm~14000rpm, the time is 8min, and the centrifugal concentration operation is repeated 3 times.

[0018] The above-mentioned method for preparing nanosilver particles for electronic 3D printing conductive ink is characterized in that the concentration of the nanosilver solution formed after the nanosilver concentrate is dispersed in deionized water in step 5 is 0.1 mol·L -1 The volume ratio of the diethanolamine to the nanosilver solution formed after dispersion is 1:20.

[0019] At the same time, the present invention also discloses a nano-silver particle for electronic 3D printing conductive ink, characterized in that the nano-silver particle prepared by the above method has a particle size of 20nm to 80nm, a uniform particle size distribution, and a quasi-spherical shape. Piezoelectric printing, aerosol jet printing and other technologies require the particle size of nano-silver particles to be basically below 100nm, and the quasi-spherical shape is more conducive to conductivity than the spherical shape, so the particle size, morphology and distribution of the nano-silver particles prepared by the present invention meet the use requirements of the above-mentioned fields.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention uses diethanolamine to exchange surface ligands with the dispersant attached to the surface of the nanosilver particles, thereby effectively removing the dispersant and modifying the nanosilver particles. There is no need to perform subsequent complex washing steps, thus avoiding the adverse effects of the post-washing steps, and effectively ensuring the conductive properties of the nanosilver particles, making them suitable for electronic 3D printing conductive inks.

[0022] 2. The nano silver particles prepared by the present invention are spherical nano particles, and the particle size of the nano silver particles can be controlled to 20nm to 80nm by controlling the reaction temperature. The reaction is mild, the operation is simple, and it is suitable for promotion and application.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The process flow chart of the preparation of nano silver particles of the present invention is shown in FIG.

[0025] Figure 2 The present invention is a process flow chart of using diethanolamine to carry out surface ligand exchange.

[0026] Figure 3 This is a scanning electron microscope image of the nanosilver particles prepared in Example 1 of the present invention.

[0027] Figure 4 This is a low-magnification transmission electron microscopy image of the nanosilver particles prepared in Example 1 of the present invention.

[0028] Figure 5 This is a high-magnification transmission electron microscopy image of the nanosilver particles prepared in Example 1 of the present invention.

[0029] Figure 6 This is the X-ray diffraction pattern of the nanosilver particles prepared in Example 1 of the present invention.

[0030] Figure 7 This is the zeta potential diagram of the nanosilver solution before and after the reaction with the addition of diethanolamine in Example 1 of the present invention.

[0031] Figure 8 This is a scanning electron microscope image of the nanosilver particles prepared in Example 2 of the present invention.

[0032] Fig. 9 This is a high-resolution transmission electron microscopy image of the nanosilver particles prepared in Example 3 of the present invention.

[0033] Fig.10 This is a high-resolution transmission electron microscopy image of the nanosilver particles prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0034] The conductivity of the deionized water used in Examples 1 to 4 of the present invention is lower than 2 μS·cm -1 .

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment adopts liquid phase chemical reduction method for preparation, and the specific process includes the following steps:

[0037] Step 1, dissolving 1.7 g of silver nitrate in 100 mL of deionized water to obtain a silver nitrate aqueous solution, and then adding 50 mL of acetonitrile to the silver nitrate aqueous solution to obtain a silver solution;

[0038] Step 2: dissolve 2.5 g of polyvinylpyrrolidone PVP with a molecular weight of 40,000 in 50 mL of deionized water to obtain a dispersant solution with a concentration of 5%; dissolve 1.76 g of ascorbic acid in 100 mL of deionized water to obtain a reducing agent solution;

[0039] Step 3, the silver solution obtained in step 1 and the dispersant solution obtained in step 2 are mixed and stirred at a speed of 300 rpm to 600 rpm, and then the temperature is raised to a reaction temperature of 25° C., and the reducing agent solution obtained in step 2 is added dropwise using a dropping funnel at a reaction temperature of 25° C., and the dropping speed is controlled during the dropping so that the dropping time is not less than 20 min. After the dropping is completed, the reaction system is continued to react at room temperature of 10° C. to 25° C. for 40 min to obtain a nano silver particle solution;

[0040] Step 4: centrifuge and concentrate the nanosilver particle solution obtained in step 3 at a speed of 11000 rpm to 14000 rpm for 8 min, then wash with deionized water, repeat the operation 3 times to obtain a nanosilver concentrate;

[0041] Step 5: Disperse the nanosilver concentrate obtained in step 4 in 100 mL of deionized water to form a solution with a concentration of 0.1 mol·L -1 The nanosilver solution was then added with 5 mL of diethanolamine and stirred for 2 h. After centrifugal concentration, it was washed with deionized water. The speed of the centrifugal concentration was 11000 rpm to 14000 rpm for 8 min. The dispersion, stirring reaction, centrifugal concentration and washing process were repeated to ensure complete ligand exchange. Figure 2 As shown, the nanosilver particles used for electronic 3D printing conductive ink are finally washed with anhydrous ethanol and concentrated.

[0042] Figure 3 The scanning electron microscope image of the nano silver particles prepared in this example is Figure 3 It can be seen that the nanosilver particles are dispersed uniformly.

[0043] Figure 4 The low-power transmission electron microscope image of the nano silver particles prepared in this example is shown in FIG. Figure 4 It can be seen that the nanosilver particles are spherical in shape and have a uniform morphology.

[0044] Figure 5 The high-magnification transmission electron microscopy image of the nano silver particles prepared in this example is shown in FIG. Figure 5It can be seen more intuitively that the size of the nanosilver particles is 60nm.

[0045] Figure 6 is the X-ray diffraction pattern of the nano silver particles prepared in this example, Figure 6 It can be seen that the component of the nano silver particles is silver, and the successful preparation of silver powder is achieved.

[0046] Figure 7 The zeta potential diagram of the nanosilver solution before and after the reaction with diethanolamine in this embodiment is shown in FIG. Figure 7 It can be seen that the zeta potential of the nanosilver solution is significantly improved after adding diethanolamine for surface ligand exchange, indicating that the surface potential of the nanosilver particles is improved, the stability of the solution is improved, and the conductivity is improved.

[0047] The dispersant polyvinylpyrrolidone PVP in step 2 of this embodiment can also be replaced by hexadecyltrimethylammonium bromide CTAB, and the reducing agent ascorbic acid can also be replaced by hydrazine hydrate, sodium borohydride, ferrous sulfate or sodium sulfite.

[0048] Example 2

[0049] The difference between this embodiment and embodiment 1 is that the reaction temperature in step 3 is 50°C.

[0050] Figure 8 The scanning electron microscope image of the nano silver particles prepared in this example is Figure 8 It can be seen that the nanosilver particles prepared in this example are dispersed relatively evenly, have a spherical shape, and have a size of less than 80 nm.

[0051] Example 3

[0052] The differences between this embodiment and embodiment 1 are as follows: 100 mL of acetonitrile is added in step 1; 1.17 g of ascorbic acid is used in step 2; and the reaction temperature in step 3 is 10°C.

[0053] Fig. 9 The high-resolution transmission electron microscopy image of the silver nanoparticles prepared in this example is shown in FIG. Fig. 9 It can be seen that the nanosilver particles prepared in this example are evenly dispersed, spherical in shape, and have a size of 40 nm.

[0054] Example 4

[0055] The differences between this embodiment and embodiment 1 are as follows: 200 mL of acetonitrile is added in step 1; 1.17 g of ascorbic acid is used in step 2; and the reaction temperature in step 3 is 0°C.

[0056] Fig.10 The high-resolution transmission electron microscopy image of the silver nanoparticles prepared in this example is shown in FIG. Fig.10It can be seen that the nanosilver particles prepared in this example are evenly dispersed, spherical in shape, and have a size of 20 nm.

[0057] Examples 1 to 4 and Figures 5 to 10 By comparison, it can be seen that due to the decrease in the concentration of the reaction system and the decrease in the reaction temperature, the reduction reaction rate of silver nitrate slows down, so that the particle size of the prepared nanosilver particles is reduced and more uniform.

[0058] In summary, the present invention discloses a method for preparing nanosilver particles for electronic 3D printing conductive ink, which is prepared by a liquid phase chemical reduction method, using diethanolamine for surface ligand exchange, and then surface-modifying the PVP-protected nanosilver particles to finally prepare the nanosilver particles. The nanosilver particles prepared by the present invention are spherical in shape, with uniform and controllable particle size distribution and good dispersibility, and the specific size is 20nm to 80nm; at the same time, the zeta potential shows that it has good stability and is suitable for preparing electronic 3D printing conductive ink. Compared with the method of using complex washing steps to remove PVP from the surface of nanosilver particles, the preparation method of the present invention omits the complex washing steps and has the advantages of mild reaction conditions and simple operation.

[0059] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing nano silver particles for electronic 3D printing conductive ink, characterized in that: Diethanolamine was used for surface ligand exchange, and the surface of the dispersant-protected nanosilver particles was modified to prepare nanosilver particles for electronic 3D printing conductive ink.

2. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 1, characterized in that: The preparation is carried out by liquid phase chemical reduction method, and the specific process includes the following steps: Step 1, dissolving silver nitrate in deionized water to obtain a silver nitrate aqueous solution, and then adding acetonitrile to the silver nitrate aqueous solution to obtain a silver solution; Step 2: dissolving a dispersant and a reducing agent in deionized water to obtain a dispersant solution and a reducing agent solution; Step 3, the silver solution obtained in step 1 and the dispersant solution obtained in step 2 are mixed and stirred evenly, then the temperature is raised to the reaction temperature, and the reducing agent solution obtained in step 2 is added dropwise at the reaction temperature to react, and after the addition is completed, the reaction system is continued to react at room temperature to obtain a nano silver particle solution; Step 4: centrifugally concentrate the nanosilver particle solution obtained in step 3, and then wash it with deionized water to obtain a nanosilver concentrate; Step 5: Disperse the nanosilver concentrate obtained in step 4 in deionized water, then add diethanolamine and stir to react, wash with deionized water after centrifugal concentration, repeat the dispersion, stirring reaction, centrifugal concentration and washing process, and finally wash with anhydrous ethanol to obtain nanosilver particles for electronic 3D printing conductive ink after concentration.

3. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The concentration of the silver nitrate aqueous solution in step 1 is 0.1 mol·L -1 The volume ratio of water to acetonitrile in the silver solution is 1:0.5-2.

4. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The dispersant in step 2 is polyvinyl pyrrolidone PVP or hexadecyl trimethyl ammonium bromide CTAB, and the molecular weight of polyvinyl pyrrolidone PVP is 40,000.

5. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The reducing agent in step 2 is ascorbic acid, hydrazine hydrate, sodium borohydride, ferrous sulfate or sodium sulfite.

6. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The stirring speed in step three is 300rpm~600rpm; the dropwise addition is carried out using a dropping funnel, and the dropping speed is controlled so that the dropping time is not less than 20min; the reaction temperature is 0~50°C, the normal temperature is 10°C~25°C, and the reaction time at normal temperature is not less than 40min.

7. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The rotation speed of the centrifugal concentration in step 4 and step 5 is 10000 rpm to 14000 rpm, the time is 8 min, and the centrifugal concentration operation is repeated 3 times.

8. The method for preparing nano silver particles for electronic 3D printing conductive ink according to claim 2, characterized in that: The concentration of the nanosilver solution formed after the nanosilver concentrate is dispersed in deionized water in step 5 is 0.1 mol·L -1 The volume ratio of the diethanolamine to the nanosilver solution formed after dispersion is 1:

20.

9. A nano silver particle for electronic 3D printing conductive ink, characterized in that: Prepared by the method described in any one of claims 1 to 8, the nanosilver particles used for electronic 3D printing conductive ink have a particle size of 20nm to 80nm, a uniform particle size distribution, and a spherical morphology.

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