Silver powder modification method and modified silver powder

Abstract

The present application relates to a silver powder modification method and modified silver powder. The silver powder modification method comprises: adding the silver powder to be modified into a surface modifier solution for reaction to obtain a silver powder slurry, wherein the surface modifier in the surface modifier solution comprises a fatty acid compound and an amine compound; separating the modified silver powder from the silver powder slurry, thereby achieving surface modification treatment of the silver powder for conductive silver paste, so as to increase the surface coverage of the silver powder, and effectively improve the wettability and dispersibility of the silver powder in the slurry, thereby improving the printability of the conductive silver paste prepared thereby, and having broad application prospects in the field of photovoltaic silver paste.

Description

Technical Field

[0001] The present application relates to the technical field of preparation of new precious metal materials, and in particular to a silver powder modification method and modified silver powder. Background Art

[0002] Photovoltaic silver paste has become the main raw material for printed solar panels due to its excellent rheological and conductive properties. Silver powder, as the main conductive phase in solar cell silver paste, accounts for about 90% of the silver paste by mass, and plays a decisive role in the rheological and conductive properties of the silver paste. With the rapid development of photovoltaics, the requirements for the printability of silver paste are getting higher and higher. Improving the interface bonding ability between silver powder and organic carriers and optimizing the wettability and dispersibility of silver powder in the paste are the current research hotspots.

[0003] However, the surface properties of silver powder used to prepare conductive silver paste in the prior art need to be improved. Summary of the invention

[0004] The purpose of the present application is to provide a silver powder modification method and modified silver powder to increase the surface coverage of the silver powder and improve the wettability and dispersibility of the silver powder in the slurry, thereby improving the printability of the conductive silver paste prepared therefrom.

[0005] An embodiment of the present application provides a silver powder modification method, which includes: adding the silver powder to be modified into a surface modifier solution for reaction to obtain a silver powder slurry, wherein the surface modifier in the surface modifier solution includes a fatty acid compound and an amine compound; and separating the modified silver powder from the silver powder slurry.

[0006] The fatty acid compound includes at least one of lauric acid, stearic acid, oleic acid and dodecyl hydroxystearic acid.

[0007] The amine compound includes at least one of oleic acid amide, stearic acid amide and octadecylamine.

[0008] The mass of the fatty acid compound in the surface modifier solution is equal to the mass of the amine compound in the surface modifier solution.

[0009] The mass fraction of the surface modifier in the surface modifier solution is 0.1-0.5%.

[0010] The silver powder to be modified is micron-sized spherical silver powder.

[0011] The method comprises adding the silver powder to be modified into a surface modifier solution for reaction to obtain a silver powder slurry, which comprises: adding the silver powder to be modified into a surface modifier solution for reaction under ultrasonic dispersion conditions to obtain a silver powder slurry.

[0012] Before adding the silver powder to be modified into the surface modifier solution for reaction to obtain the silver powder slurry, the silver powder modification method further comprises: dissolving the surface modifier in the dispersion to obtain the surface modifier solution, wherein the ratio of the mass of the dispersion to the mass of the silver powder to be modified is 0.5 to 3.

[0013] Wherein, the dispersion liquid is ethanol or acetone.

[0014] The embodiment of the present application also provides a modified silver powder, which is prepared by any of the above-mentioned silver powder modification methods.

[0015] The silver powder modification method and modified silver powder provided in the present application are obtained by adding the silver powder to be modified into a surface modifier solution for reaction, wherein the surface modifier in the surface modifier solution includes a fatty acid compound and an amine compound, and then separating the modified silver powder from the silver powder slurry, thereby achieving surface modification treatment of the silver powder for conductive silver paste to increase the surface coverage of the silver powder, and effectively improving the wettability and dispersibility of the silver powder in the slurry, thereby improving the printability of the conductive silver paste prepared thereby, and having broad application prospects in the field of photovoltaic silver paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0017] Figure 1 It is a schematic diagram of the process of the silver powder modification method provided in the embodiment of the present application;

[0018] Figure 2 It is another schematic diagram of the process of the silver powder modification method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0019] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0020] In the following description of the present application, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0021] In the following description of the present application, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0023] The following is a detailed description with reference to specific embodiments. It should be noted that the serial numbers of the following embodiments are not intended to limit the preferred order of the embodiments.

[0024] See also Figure 1 , Figure 1 : is a schematic diagram of the process of the silver powder modification method provided in the embodiment of the present application. The specific process of the silver powder modification method can be as follows:

[0025] Step S12: adding the silver powder to be modified into a surface modifier solution for reaction to obtain a silver powder slurry, wherein the surface modifier in the surface modifier solution includes a fatty acid compound and an amine compound.

[0026] In this embodiment, the fatty acid compound may include at least one of lauric acid, stearic acid, oleic acid and dodecyl hydroxy stearic acid, and in some examples, the fatty acid compound may be lauric acid, or may be stearic acid. The amine compound may include at least one of oleamide, stearic acid amide and octadecylamine, and in some examples, the amine compound may be oleamide.

[0027] In some embodiments, the ratio of the mass of the fatty acid compound in the surface modifier solution to the mass of the amine compound in the surface modifier solution may be 0.5 to 2, for example, 0.5, 1 or 2.

[0028] In some specific embodiments, the mass of the fatty acid compound in the surface modifier solution may be equal to the mass of the amine compound in the surface modifier solution.

[0029] In some specific embodiments, the fatty acid compound and the amine compound in the surface modifier solution may be lauric acid and oleamide, respectively. Accordingly, the mass of lauric acid in the surface modifier solution may be equal to the mass of oleamide in the surface modifier solution, for example, both may be 6 g; or, the mass of lauric acid in the surface modifier solution may be different from the mass of oleamide in the surface modifier solution, for example, 4 g and 8 g, or 8 g and 4 g, respectively.

[0030] In some specific embodiments, the fatty acid compound and the amine compound in the surface modifier solution can be stearic acid and oleamide, respectively. Accordingly, the mass of stearic acid in the surface modifier solution and the mass of oleamide in the surface modifier solution can be equal, for example, both can be 6 g.

[0031] In some specific embodiments, the mass fraction of the surface modifier in the surface modifier solution may be 0.1 to 0.5‰ to ensure the surface modification effect on the silver powder.

[0032] In some specific embodiments, in order to obtain the above-mentioned surface modifier solution, such as Figure 2 As shown, before the above step S12, the above silver powder modification method may further include:

[0033] Step S11. Dissolving the surface modifier in the dispersion to obtain a surface modifier solution.

[0034] The dispersion liquid may be an organic solvent such as ethanol or acetone, and the mass ratio of the dispersion liquid to the mass of the silver powder to be modified may be 0.5-3.

[0035] In some embodiments, the above step S12 may specifically include: adding the silver powder to be modified to the surface modifier solution under ultrasonic dispersion conditions to react and obtain a silver powder slurry. Specifically, the silver powder to be modified may be added to the surface modifier solution at a preset rate under ultrasonic dispersion conditions to react, and the silver powder slurry may be obtained after the reaction is completed. The preset rate may be 0 to 40 kg / h, and the reaction time may be 0.5 to 3 h.

[0036] Furthermore, in a specific implementation, the surface modifier solution can be added into an ultrasonic dispersion kettle, and then under ultrasonic dispersion, the silver powder to be modified is added into the surface modifier solution at a preset rate to react, and after the reaction is completed, a silver powder slurry is obtained.

[0037] The ultrasonic dispersion kettle may have at least stirring, ultrasonic and temperature control functions. Accordingly, the above-mentioned adding the silver powder to be modified into the surface modifier solution at a preset rate for reaction under ultrasonic dispersion may refer to: adding the silver powder to be modified into the surface modifier solution at a preset rate for reaction under the condition of turning on the ultrasonic and stirring of the ultrasonic dispersion kettle.

[0038] In some examples, the ultrasonic frequency of the ultrasonic dispersion kettle may be 10-30 KHz, the stirring rate of the ultrasonic dispersion kettle may be 500-1000 rpm, and the temperature control range of the ultrasonic dispersion kettle may be 20-50° C.

[0039] Step S14: separating the modified silver powder from the silver powder slurry.

[0040] In this embodiment, the silver powder to be modified and the modified silver powder obtained by performing surface modification treatment on the silver powder may have the same or substantially the same particle size and morphology.

[0041] Specifically, the particle size of the silver powder to be modified may be micron-sized, and the microscopic morphology of the silver powder to be modified may be spherical particles. Correspondingly, the particle size of the modified silver powder may also be micron-sized, and the microscopic morphology of the modified silver powder may also be spherical particles. In some examples, the silver powder to be modified and the modified silver powder may both be micron-sized silver powders, and may specifically be micron-sized spherical silver powders.

[0042] In some embodiments, the particle size of the silver powder to be modified may be 1 to 5 μm, and the bulk density of the silver powder to be modified may be 2 to 4 g / cm 3 The specific surface area of ​​the silver powder to be modified can be 0.2 to 1 m 2 / g.

[0043] In one embodiment, the above step S14 may specifically include: performing solid-liquid separation on the silver powder slurry, and washing and drying the separated solid to obtain surface-modified silver powder (i.e., modified silver powder). The drying time may be 2 to 6 hours, and the drying temperature may be 50 to 80°C.

[0044] Furthermore, for ease of understanding, the present application is further described in detail below through four specific embodiments (ie, Embodiment 1, Embodiment 2, Embodiment 3 and Embodiment 4), and Comparative Examples 1 and 2 are used as controls.

[0045] Example 1

[0046] In Example 1, the specific process of the silver powder modification method can be as follows:

[0047] Step S21. Weigh 6 g of lauric acid (ie, fatty acid compound) and 6 g of oleamide (ie, amine compound) respectively, dissolve them in 100 g of ethanol, and then add them to 4 kg of ethanol to obtain a surface modifier solution.

[0048] Step S22. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0049] Step S23. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain surface-modified silver powder A1 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0050] Example 2

[0051] The silver powder modification method provided in Example 2 is basically the same as the silver powder modification method provided in Example 1, except that the mass of lauric acid is adjusted from 6 g to 8 g, and the mass of oleamide is adjusted from 6 g to 4 g. Accordingly, in Example 2, the specific process of the silver powder modification method can be as follows:

[0052] Step S31. Weigh 8 g of lauric acid and 4 g of oleamide respectively, dissolve them in 100 g of ethanol, and then add them to 4 kg of ethanol to obtain a surface modifier solution.

[0053] Step S32. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0054] Step S33. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain surface-modified silver powder A2 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0055] Example 3

[0056] The silver powder modification method provided in Example 3 is basically the same as the silver powder modification method provided in Example 1. The difference between the two is that the mass of lauric acid is adjusted from 6g to 4g, and the mass of oleamide is adjusted from 6g to 8g. Accordingly, in Example 3, the specific process of the silver powder modification method can be as follows:

[0057] Step S41. Weigh 4 g of lauric acid and 84 g of oleamide respectively, dissolve them in 100 g of ethanol, and then add them to 4 kg of ethanol to obtain a surface modifier solution.

[0058] Step S42. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0059] Step S43. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain surface-modified silver powder A3 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0060] Example 4

[0061] The silver powder modification method provided in Example 4 is basically the same as the silver powder modification method provided in Example 1, and the difference between the two is that lauric acid is replaced by stearic acid. Accordingly, in Example 4, the specific process of the silver powder modification method can be as follows:

[0062] Step S51. Weigh 6 g of stearic acid and 6 g of oleamide respectively, dissolve them in 100 g of ethanol, and then add them to 4 kg of ethanol to obtain a surface modifier solution.

[0063] Step S52. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0064] Step S53. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain surface-modified silver powder A4 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0065] Comparative Example 1

[0066] The silver powder modification method provided in Comparative Example 1 is basically the same as the silver powder modification method provided in Example 1, except that 6 g of lauric acid and 6 g of oleamide are replaced by 12 g of lauric acid, that is, the surface modifier in the surface modifier solution is only lauric acid. Accordingly, in Comparative Example 1, the specific process of the silver powder modification method can be as follows:

[0067] Step S61. Weigh 12 g of lauric acid, dissolve it in 100 g of ethanol, and then add it to 4 kg of ethanol to obtain a surface modifier solution.

[0068] Step S62. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0069] Step S63. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain surface-modified silver powder B1 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0070] Comparative Example 2

[0071] The silver powder modification method provided in Comparative Example 2 is basically the same as the silver powder modification method provided in Example 1, except that 6 g of lauric acid and 6 g of oleic acid amide are replaced by 12 g of oleic acid amide, that is, the surface modifier in the surface modifier solution is only oleic acid amide. Accordingly, in Comparative Example 2, the specific process of the silver powder modification method can be as follows:

[0072] Step S71. Weigh 12 g of oleic acid amide, dissolve it in 100 g of ethanol, and then add it to 4 kg of ethanol to obtain a surface modifier solution.

[0073] Step S72. Under the conditions of a temperature of 25° C., a stirring speed of 500 rpm, and an ultrasonic frequency of 20 KHz, micron-sized silver powder (ie, silver powder to be modified) is added to the surface modifier solution at a feeding rate of 6 kg / min for reaction.

[0074] Step S73. After the reaction is continued for 1 hour, solid-liquid separation, washing and drying are performed to obtain the surface-modified silver powder B2 (ie, modified silver powder), wherein the drying temperature is 55° C. and the drying time is 2 hours.

[0075] Specifically, by testing the surface-modified silver powders A1 / A2 / A3 / A4 / B1 / B2 obtained in Example 1, Example 2, Example 3, Example 4, Comparative Example 1 and Comparative Example 2, the performance parameter results of the silver powders A1 / A2 / A3 / A4 / B1 / B2 are shown in Table 1 below.

[0076] Table 1

[0077]

[0078] Furthermore, according to Table 1, by compounding in a certain proportion, adding surface modifiers of different polarities (i.e., fatty acid compounds and amine compounds) can effectively improve the surface coverage of the silver powder, and make the silver powder and the organic carrier have better wettability, thereby improving the wettability and dispersibility of the silver powder in the slurry, thereby improving the printability of the conductive silver paste prepared therefrom.

[0079] Furthermore, compared with the method in which the surface modifier in the surface modifier solution includes only one of the fatty acid compound and the amine compound, the method in which the surface modifier in the surface modifier solution includes both the fatty acid compound and the amine compound can obtain a better silver powder surface modification effect and has a direct impact on the tap density, viscosity and printability of the silver powder.

[0080] Moreover, when the mass ratio of lauric acid to oleic acid amide is 1:1, the surface modification effect of silver powder is best, the surface coverage of silver powder is the highest, and the dispersibility of silver powder itself and the wettability with slurry are better, the tap density of silver powder is higher, the resistivity after printing is lower, and the printability of silver powder is better.

[0081] From the above, it can be seen that the silver powder modification method provided in this embodiment is achieved by adding the silver powder to be modified into a surface modifier solution for reaction to obtain a silver powder slurry, wherein the surface modifier in the surface modifier solution includes a fatty acid compound and an amine compound, and then separating the modified silver powder from the silver powder slurry, thereby achieving surface modification of the silver powder for conductive silver paste to increase the surface coverage of the silver powder, and effectively improve the wettability and dispersibility of the silver powder in the slurry, thereby improving the printability of the conductive silver paste prepared thereby, and has broad application prospects in the field of photovoltaic silver paste.

[0082] In order to better implement the silver powder modification method provided in the embodiments of the present application, the embodiments of the present application also provide a modified silver powder, which is prepared by the silver powder modification method provided in any of the above embodiments.

[0083] Specifically, the particle size of the modified silver powder can be micrometer-sized, and the microscopic morphology of the modified silver powder can be spherical particles. In some examples, the modified silver powder can be micrometer-sized spherical silver powder.

[0084] Specifically, the modified silver powder can have a high coverage rate, so that the dispersibility of the modified silver powder itself and the wettability between the modified silver powder and the slurry can be better. The modified silver powder has a high tap density, a lower resistivity after printing, and better printability.

[0085] In some embodiments, the tap density of the modified silver powder may be greater than or equal to 5.8 g / ml, for example, 5.8 g / ml, 5.9 g / ml or 6.0 g / ml, etc. The coating amount of the modified silver powder may be greater than or equal to 0.04%, for example, 0.04, 0.06 or 0.07, etc. The 50 rpm viscosity of the modified silver powder may be less than or equal to 100 MPa·s, for example, 100 MPa·s, 92 MPa·s, 90 MPa·s or 85 MPa·s, etc. The resistance of the modified silver powder when its line width is 9 μm may be less than or equal to 46 mΩ, for example, 46 mΩ, 35 mΩ or 25 mΩ, etc.

[0086] Furthermore, the modified silver powder in the embodiment of the present application is prepared by the silver powder modification method provided in any of the above embodiments, and therefore has all the same beneficial effects, which will not be described in detail in this embodiment.

[0087] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0088] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for modifying silver powder, characterized in that: include: Under ultrasonic dispersion conditions, adding the silver powder to be modified into a surface modifier solution at a preset rate for reaction, the reaction time is 0.5 to 3 hours, and obtaining a silver powder slurry after the reaction is completed, wherein the preset rate is 0 to 40 kg / h, the surface modifier in the surface modifier solution includes a fatty acid compound and an amine compound, and the mass fraction of the surface modifier in the surface modifier solution is 0.1 to 0.5%, and the ratio of the mass of the fatty acid compound in the surface modifier solution to the mass of the amine compound in the surface modifier solution is 0.5 to 2; separating modified silver powder from the silver powder slurry; Wherein, before adding the silver powder to be modified into the surface modifier solution at a preset rate for reaction, the silver powder modification method further comprises: The surface modifier is dissolved in a dispersion to obtain the surface modifier solution, wherein the ratio of the mass of the dispersion to the mass of the silver powder to be modified is 0.5-3.

2. The silver powder modification method according to claim 1, characterized in that: The fatty acid compound includes at least one of lauric acid, stearic acid, oleic acid and dodecyl hydroxystearic acid.

3. The silver powder modification method according to claim 1, characterized in that: The amine compound includes at least one of oleic acid amide, stearic acid amide and octadecylamine.

4. The silver powder modification method according to claim 1, characterized in that: The mass of the fatty acid compound in the surface modifier solution is equal to the mass of the amine compound in the surface modifier solution.

5. The silver powder modification method according to claim 1, characterized in that: The silver powder to be modified is micron-sized spherical silver powder.

6. The silver powder modification method according to claim 1, characterized in that: The dispersion liquid is ethanol or acetone.

7. A modified silver powder, characterized in that: The silver powder is prepared by the silver powder modification method according to any one of claims 1 to 6.

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