Surface modification method of metal powder and modified metal powder

Abstract

The invention discloses a surface modification method of metal powder and modified metal powder. The invention relates to a surface modification method of metal powder, which comprises the following steps: firstly, adding the metal powder into a coupling agent solution, and uniformly dispersing; then, adding a modifier solution, and uniformly dispersing; and finally, the temperature is increased to 40-80 DEG C, a heat preservation reaction is conducted for 2-4 h under the stirring condition at the rotating speed of 350-500 rpm, the temperature is reduced to the room temperature, the metal powder is separated, drying is conducted, and the surface-modified metal powder is obtained. Wherein the modifier is selected from one or more of amino silicon oil, dibenzylidene sorbitol and a compound as shown in a general formula X-R-Y, X and Y independently represent a hydrogen atom,-SH,-COOH or-NH2, X and Y do not represent the hydrogen atom at the same time, and R independently represents C6-C18 alkyl or C6-C10 substituted / unsubstituted aryl. The modification method is suitable for various kinds of metal powder, the modification uniformity is good, the sphericity degree of the modified powder is remarkably improved, and the modified powder has better fluidity. The invention correspondingly provides the modified metal powder obtained through modification with the method.

Description

Technical Field

[0001] The present application relates to the technical field of composite material preparation, and in particular to a surface modification method of metal powder and modified metal powder. Background Art

[0002] Metal powders are widely used in powder metallurgy, conductive adhesives and pastes, electromagnetic shielding composite materials, thermal conductive coatings, metal paints, new energy and other fields. When used in these fields, metal powders usually need to be surface modified. A layer of organic matter is coated on the surface of the powder to form a certain adhesion or to form good compatibility with organic solvents and matrices. Otherwise, it is difficult for the metal powder to form a product with the required performance.

[0003] There are two main types of metal powder modification methods used in traditional industry:

[0004] 1) Dry powder modification. Dry powder modification processes are mostly used for non-metallic mineral powders that do not require high powder morphology, including high-speed mixing, stirring, ball milling, airflow milling, etc. However, when these processes are applied to metal powder modification, due to the high specific gravity, high hardness or ductility, and oxidation resistance of metal powders, problems such as the introduction of impurities, deformation and oxidation of metal powders, and unsatisfactory coating effects will occur during the modification process.

[0005] 2) Wet powder modification, generally using a modifier solution to modify the metal powder, this type of method has many problems such as low modification efficiency, long process, low modifier utilization, poor quantitativeness, unstable manual operation, etc., and is not suitable for large-scale continuous production. For example, the related technology CN116206799A discloses a surface modification method for micron silver-coated copper powder, wherein the silver-coated copper powder and the modifier are respectively added to anhydrous ethanol, stirred, and then treated with an ultrasonic disperser for 1 hour, and finally dried to obtain surface-modified silver-coated copper powder; This method is relatively simple, but the utilization rate of the modifier is low, the quantitativeness is poor, and the consistency of the surface modification of the silver-coated copper powder cannot be guaranteed; WO2016166823A1 discloses a modification method for inorganic fillers, which uses organic matter containing polar groups as a modifier to modify the inorganic filler, which can improve the compatibility of the inorganic filler in the organic material, but does not teach that this modification method is suitable for metal powders, and it teaches that the presence of a known coupling agent will weaken the interaction between the organic modifier and the inorganic filler, which is not conducive to obtaining the expected modification effect.

[0006] Therefore, it is necessary to provide a new modification method suitable for metal powder modification. Summary of the invention

[0007] In order to suppress the oxidation effect of the modification process on the metal powder and improve the sphericity of the metal powder, the present invention provides a surface modification method of the metal powder and the modified metal powder.

[0008] In a first aspect, the present invention provides a method for surface modification of metal powder, which specifically adopts the following technical scheme.

[0009] A method for surface modification of metal powder comprises the following steps:

[0010] S1. Add metal powder to coupling agent solution and disperse evenly to obtain pre-dispersion solution;

[0011] The amount of metal powder added is 0.5 g / mL relative to the volume of the coupling agent solution; the coupling agent solution is prepared by dissolving a silane coupling agent in water, wherein the concentration of the silane coupling agent is 15-25 g / L;

[0012] S2, adding the modifier solution to the pre-dispersion solution obtained in step S1, dispersing evenly, to obtain a reaction solution;

[0013] The volume ratio of the modifier solution added in step S2 to the coupling agent solution in step S1 is (1-3):3;

[0014] The modifier solution is prepared by dissolving a modifier and a dispersant in a solvent, wherein the concentration of the modifier is 15-25 g / L and the concentration of the dispersant is 2-8 g / L;

[0015] The modifier is selected from one or more of (1) amino silicone oil, (2) dibenzylidene sorbitol and (3) a compound represented by the general formula XRY, wherein X and Y independently represent a hydrogen atom, -SH, -COOH or -NH2, and X and Y do not represent a hydrogen atom at the same time, and R independently represents a C6-C18 hydrocarbon group or a C6-C10 substituted / unsubstituted aromatic group;

[0016] S3, heating the reaction solution obtained in step S2 to 40-80°C, stirring at 350-500 rpm for 2-4 hours, cooling to room temperature, separating the metal powder, and drying to obtain surface-modified metal powder.

[0017] Furthermore, in step S1, the concentration of silane coupling agent in the coupling agent solution is 20 g / L; in step S2, the concentration of modifier in the modifier solution is 20 g / L and the concentration of dispersant is 5 g / L, and the volume ratio of the added modifier solution to the coupling agent solution in step S1 is 2:3.

[0018] Furthermore, the dispersant is selected from one or more of gelatin, polyvinyl pyrrolidone, triethylhexyl phosphate, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum, and polyethylene glycol esters of fatty acids.

[0019] Furthermore, the solvent is water, anhydrous ethanol or ethanol aqueous solution.

[0020] Furthermore, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanatepropyltriethoxysilane.

[0021] Furthermore, the metal powder is silver powder, copper powder or silver-coated copper powder.

[0022] Further, in step S1, after adding the metal powder into the coupling agent solution, the mixture is stirred at a speed of 500-600 rpm for 30 minutes to be evenly dispersed to obtain a pre-dispersion solution.

[0023] Further, in step S2, after adding the modifier solution to the pre-dispersed liquid, ultrasonic dispersion is performed for 1 hour, the ultrasonic power is 35 W / L, and the ultrasonic frequency is 40 kHz-100 kHz to obtain a reaction solution.

[0024] Furthermore, in step S3, after the metal powder is separated, it is dried at 60° C.-80° C. for 12 hours to obtain surface-modified metal powder.

[0025] In a second aspect, the present invention provides a modified metal powder, which is obtained by modifying the surface of the metal powder using the above-mentioned method for modifying the surface of the metal powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the SEM image of the modified silver-coated copper powder in Example 1;

[0027] Figure 2 This is a diagram showing the dispersion effect of the modified silver-coated copper powder in a mixed solution of water and an organic phase according to Example 1;

[0028] Figure 3 This is the SEM image of the modified silver-coated copper powder in Example 2;

[0029] Figure 4 This is a diagram showing the dispersion effect of the modified silver-coated copper powder in a mixed solution of water and an organic phase according to Example 2;

[0030] Figure 5 This is the SEM image of the modified silver-coated copper powder in Example 3;

[0031] Figure 6 This is a diagram showing the dispersion effect of the modified silver-coated copper powder in a mixed solution of water and an organic phase according to Example 3;

[0032] Figure 7 This is the SEM image of the modified silver-coated copper powder in Example 4;

[0033] Figure 8This is a diagram showing the dispersion effect of the modified silver-coated copper powder in a mixed solution of water and an organic phase according to Example 5; DETAILED DESCRIPTION

[0034] The present application is further described in detail below with reference to the embodiments.

[0035] Example

[0036] It should be noted that the powder applicable to the method of the present invention may be metal powders such as silver powder, copper powder, and silver-coated copper powder. The embodiments only use silver-coated copper powder as an example. The type of silane coupling agent in the present invention is not specifically limited and can be selected according to actual needs. Specifically, it can be one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanatepropyltriethoxysilane. The following embodiments only use vinyltriethoxysilane as an example. Similarly, the type of dispersant in the present invention is not specifically limited. Specifically, it can be one or more of gelatin, polyvinylpyrrolidone, triethylhexylphosphoric acid, sodium lauryl sulfate, methylpentanol, cellulose derivatives, polyacrylamide, gum, and fatty acid polyethylene glycol esters. The following embodiments only use polyvinylpyrrolidone and gelatin as examples, which are not limitations of the present invention.

[0037] <Example 1>

[0038] A surface modification method for silver-coated copper powder, comprising the following steps:

[0039] S1, adding 300g of silver-coated copper powder to 600ml of coupling agent solution, stirring at 500rpm for 30min to disperse evenly, to obtain a pre-dispersion solution; the coupling agent solution is prepared by dissolving vinyltriethoxysilane in water, wherein the concentration of vinyltriethoxysilane is 20g / L;

[0040] S2, adding 400 ml of modifier solution to the pre-dispersion liquid obtained in step S1, and ultrasonically dispersing for 1 hour, with an ultrasonic power of 35 W / L and an ultrasonic frequency of 40 kHz, to obtain a reaction solution; the modifier solution is prepared by dissolving oleylamine and polyvinyl pyrrolidone in anhydrous ethanol, wherein the concentration of oleylamine is 20 g / L and the concentration of polyvinyl pyrrolidone (PVP) is 5 g / L;

[0041] S3, the reaction solution obtained in step S2 was heated to 40°C, stirred at 500 rpm for 2 hours, cooled to room temperature, the silver-coated copper powder was separated, and dried at 60°C for 12 hours to obtain surface-modified silver-coated copper powder with a yield of 98%. The SEM image of the modified silver-coated copper powder is shown in Figure 1 The dispersion effect of modified silver-coated copper powder in water and organic phase mixed solution is shown in Figure 2 .

[0042] <Example 2>

[0043] A surface modification method for silver-coated copper powder, comprising the following steps:

[0044] S1, adding 300g of silver-coated copper powder to 600ml of coupling agent solution, stirring at 500rpm for 30min to disperse evenly, to obtain a pre-dispersion solution; the coupling agent solution is prepared by dissolving vinyltriethoxysilane in water, wherein the concentration of vinyltriethoxysilane is 20g / L;

[0045] S2, adding 400 ml of the modifier solution to the pre-dispersed liquid obtained in step S1, and ultrasonically dispersing for 1 hour, with an ultrasonic power of 35 W / L and an ultrasonic frequency of 60 kHz, to obtain a reaction solution; the modifier solution is prepared by dissolving oleylamine and polyvinyl pyrrolidone in anhydrous ethanol, wherein the concentration of oleylamine is 20 g / L and the concentration of polyvinyl pyrrolidone is 5 g / L;

[0046] S3, the reaction solution obtained in step S2 was heated to 60°C, stirred at 450 rpm for 2 hours, cooled to room temperature, the silver-coated copper powder was separated, and dried at 65°C for 12 hours to obtain surface-modified silver-coated copper powder with a yield of 97%. The SEM image of the modified silver-coated copper powder is shown in Figure 3 The dispersion effect of modified silver-coated copper powder in water and organic phase mixed solution is shown in Figure 4 .

[0047] <Example 3>

[0048] A surface modification method for silver-coated copper powder, comprising the following steps:

[0049] S1, adding 300g of silver-coated copper powder to 600ml of coupling agent solution, stirring at 600rpm for 30min to disperse evenly, to obtain a pre-dispersion solution; the coupling agent solution is prepared by dissolving vinyltriethoxysilane in water, wherein the concentration of vinyltriethoxysilane is 20g / L;

[0050] S2, adding 400 ml of the modifier solution to the pre-dispersed liquid obtained in step S1, and ultrasonically dispersing for 1 hour, with an ultrasonic power of 35 W / L and an ultrasonic frequency of 80 kHz, to obtain a reaction solution; the modifier solution is prepared by dissolving oleylamine and gelatin in anhydrous ethanol, wherein the concentration of oleylamine is 20 g / L and the concentration of gelatin is 5 g / L;

[0051] S3, the reaction solution obtained in step S2 was heated to 60°C, stirred at 400 rpm for 2 hours, cooled to room temperature, the silver-coated copper powder was separated, and dried at 70°C for 12 hours to obtain surface-modified silver-coated copper powder with a yield of 97%. The SEM image of the modified silver-coated copper powder is shown in Figure 5 The dispersion effect of modified silver-coated copper powder in water and organic phase mixed solution is shown in Figure 6 .

[0052] <Example 4>

[0053] A surface modification method for silver-coated copper powder, comprising the following steps:

[0054] S1, adding 300g of silver-coated copper powder to 600ml of coupling agent solution, stirring at 600rpm for 30min to disperse evenly, to obtain a pre-dispersion solution; the coupling agent solution is prepared by dissolving vinyltriethoxysilane in water, wherein the concentration of vinyltriethoxysilane is 20g / L;

[0055] S2, adding 400 ml of modifier solution to the pre-dispersed liquid obtained in step S1, and ultrasonically dispersing for 1 hour, with an ultrasonic power of 35 W / L and an ultrasonic frequency of 100 kHz, to obtain a reaction solution; the modifier solution is prepared by dissolving ricinoleic acid and polyvinyl pyrrolidone in anhydrous ethanol, wherein the concentration of ricinoleic acid is 20 g / L and the concentration of polyvinyl pyrrolidone is 5 g / L;

[0056] S3, the reaction solution obtained in step S2 was heated to 60°C, stirred at 350 rpm for 2 hours, cooled to room temperature, the silver-coated copper powder was separated, and dried at 80°C for 12 hours to obtain surface-modified silver-coated copper powder with a yield of 97%. The SEM image of the modified silver-coated copper powder is shown in Figure 7 The dispersion effect of modified silver-coated copper powder in water and organic phase mixed solution is shown in Figure 8 .

[0057] The particle size distribution range, sphericity, resistivity, anti-oxidation resistivity, bulk density and tap density data of the silver-coated copper powder before and after modification were recorded; the particle size was measured by a laser particle size distribution instrument, and the sphericity was calculated based on the area average diameter and volume average diameter measured by the laser particle size distribution instrument; the anti-oxidation resistivity refers to the resistivity obtained after the powder was calcined at 180°C for 10 minutes.

[0058] The test results of Examples 1-4 are recorded in Table 1.

[0059] Table 1. Experimental results of the examples Table 1

[0060]

[0061] It can be seen from the test results that the sphericity of the modified powder is higher than that of the powder before modification, which means that the modification of metal powder by the method of the present invention is beneficial to improving the sphericity of the powder and the modification uniformity is good. The data show that the fluidity of the powder is better after modification.

[0062] <Example 5-6>

[0063] Examples 5-6 are all based on Example 1, and differ from Example 1 in that the volume ratio of the coupling agent solution to the modifier solution is different.

[0064] In Example 5, the volume ratio of the modifier solution added in step S2 to the coupling agent solution in step S1 is 1:3, that is, 200 ml of the modifier solution is added in step S2.

[0065] In Example 6, the volume ratio of the modifier solution added in step S2 to the coupling agent solution in step S1 is 1:1, that is, 600 ml of the modifier solution is added in step S2.

[0066] The sphericity, resistivity, anti-oxidation resistivity, bulk density and tap density data of the silver-coated copper powder before and after modification were recorded, as shown in Table 2.

[0067] Table 2. Experimental results of the examples Table 2

[0068]

[0069] <Example 7-13>

[0070] Examples 7-13 are all based on Example 1, and differ from Example 1 in that the composition of the modifier solution in step S2 is different, as shown in Table 3.

[0071] Table 3. Composition of the modifier solution in step S2

[0072]

[0073] In Example 11, the weight ratio of oleylamine to lauryl mercaptan is 1:0.5.

[0074] In Example 12, the weight ratio of ricinoleic acid to lauryl mercaptan is 1:0.5.

[0075] In Example 13, the weight ratio of oleylamine, ricinoleic acid and dodecanoic acid is 1:0.5:0.5.

[0076] The sphericity, resistivity, anti-oxidation resistivity, bulk density and tap density data of the silver-coated copper powder before and after modification are recorded, as shown in Table 4.

[0077] Table 4. Experimental results of the embodiment Table 3

[0078]

[0079] <Examples 14-15>

[0080] Examples 14-15 are based on Example 1, and differ from Example 1 in that the reaction temperature and time of step S3 are different, as shown in Table 5.

[0081] Table 5. Step S3 reaction temperature and timetable

[0082] Examples Reaction temperature Reaction time Example 1 40℃ 2 / h Embodiment 14 40℃ 4 / h Embodiment 15 80℃ 2 / h

[0083] The sphericity, resistivity, anti-oxidation resistivity, bulk density and tap density data of the silver-coated copper powder before and after modification are recorded, as shown in Table 6.

[0084] Table 6. Example test results Table 4

[0085]

[0086] Comparative Example

[0087] <Comparative Example 1>

[0088] A surface modification method for silver-coated copper powder, comprising the following steps:

[0089] 300g of silver-coated copper powder was added to 1000ml of coupling agent solution, and the mixture was stirred at 500rpm for 30min to be evenly dispersed; the coupling agent solution was prepared by dissolving vinyltriethoxysilane in water, wherein the concentration of vinyltriethoxysilane was 20g / L; the solution was heated to 40°C, stirred at 500rpm for 2h, cooled to room temperature, the silver-coated copper powder was separated, and dried at 60°C for 12h to obtain surface-modified silver-coated copper powder.

[0090] <Comparative Example 2>

[0091] A surface modification method for silver-coated copper powder, comprising the following steps:

[0092] S1. Add 300g of silver-coated copper powder to 1000ml of modifier solution and perform ultrasonic dispersion for 1h. The ultrasonic power is 35W / L and the ultrasonic frequency is 40kHz. The modifier solution is prepared by dissolving oleylamine and polyvinylpyrrolidone in anhydrous ethanol, wherein the concentration of oleylamine is 20g / L and the concentration of polyvinylpyrrolidone (PVP) is 5g / L. Heat the solution to 40°C, stir at 500rpm for 2h, cool to room temperature, separate the silver-coated copper powder, and dry at 60°C for 12h to obtain surface-modified silver-coated copper powder.

[0093] The sphericity, resistivity, anti-oxidation resistivity, bulk density and tap density data of the silver-coated copper powder before and after modification are recorded, as shown in Table 7.

[0094] Table 7. Test results of Example 1 and Comparative Examples 1-2

[0095]

[0096] It can be seen from the test results that: using only silane coupling agent or modifier has poor modification effect on metal powder and poor effect on improving the sphericity of metal powder.

[0097] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for surface modification of metal powder, characterized in that: The steps include: S1. Add metal powder to coupling agent solution and disperse evenly to obtain pre-dispersion solution; The amount of metal powder added is 0.5 g / mL relative to the volume of the coupling agent solution; the coupling agent solution is prepared by dispersing a silane coupling agent in water, wherein the concentration of the silane coupling agent is 15-25 g / L; S2, adding the modifier solution to the pre-dispersion liquid obtained in step S1, dispersing evenly, to obtain a reaction solution; The volume ratio of the modifier solution added in step S2 to the coupling agent solution in step S1 is (1-3):3; The modifier solution is prepared by dissolving a modifier and a dispersant in a solvent, wherein the concentration of the modifier is 15-25 g / L and the concentration of the dispersant is 2-8 g / L; The modifier is selected from one or more of (1) amino silicone oil, (2) dibenzylidene sorbitol and (3) a compound represented by the general formula XRY, wherein X and Y independently represent a hydrogen atom, -SH, -COOH or -NH2, and X and Y do not represent a hydrogen atom at the same time, and R independently represents a C6-C18 hydrocarbon group or a C6-C10 substituted / unsubstituted aromatic group; S3, raising the temperature of the reaction solution obtained in step S2 to 40-80°C, stirring at 350-500 rpm for 2-4 hours, cooling to room temperature, separating the metal powder, and drying to obtain surface-modified metal powder.

2. The surface modification method of metal powder according to claim 1, characterized in that: In step S1, the concentration of silane coupling agent in the coupling agent solution is 20 g / L; in step S2, the concentration of modifier in the modifier solution is 20 g / L and the concentration of dispersant is 5 g / L, and the volume ratio of the added modifier solution to the coupling agent solution in step S1 is 2:

3.

3. The surface modification method of metal powder according to claim 1, characterized in that: The dispersant is selected from one or more of gelatin, polyvinyl pyrrolidone, triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyethylene glycol esters.

4. The surface modification method of metal powder according to claim 1, characterized in that: The solvent is water, anhydrous ethanol or ethanol aqueous solution.

5. The surface modification method of metal powder according to claim 1, characterized in that: The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanatepropyltriethoxysilane.

6. The surface modification method of metal powder according to claim 1, characterized in that: The metal powder is silver powder, copper powder or silver-coated copper powder.

7. The surface modification method of metal powder according to any one of claims 1 to 6, characterized in that: Step S1, adding metal powder to the coupling agent solution, stirring at a speed of 500-600 rpm for 30 minutes to disperse evenly, to obtain a pre-dispersion solution.

8. The surface modification method of metal powder according to any one of claims 1 to 6, characterized in that: Step S2, after adding the modifier solution to the pre-dispersed liquid, ultrasonic dispersion is performed for 1 hour, the ultrasonic power is 35 W / L, and the ultrasonic frequency is 40 kHz-100 kHz to obtain a reaction solution.

9. The surface modification method of metal powder according to any one of claims 1 to 6, characterized in that: Step S3, after separating the metal powder, drying it at 60° C.-80° C. for 12 hours to obtain surface-modified metal powder.

10. A modified metal powder obtained by the surface modification method of metal powder according to any one of claims 1 to 9.

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