Aluminum paste for powder lamination aluminum foil, aluminum foil and preparation method

Abstract

The invention provides aluminum paste for a powder lamination aluminum foil, the aluminum foil and a preparation method, and belongs to the technical field of aluminum paste preparation. The aluminum paste comprises the following components in parts by mass: 60-80 parts of aluminum powder; wherein the aluminum powder comprises aluminum powder; the D50 of the first aluminum powder is 1-2 [mu] m, the D50 of the second aluminum powder is 3-4 [mu] m, and the D50 of the third aluminum powder is 6-8 [mu] m; 5-10 parts by mass of a binder; 15-30 parts by mass of a solvent; 0.5-1 part by mass of a leveling agent; 0.5-3 parts by mass of a dispersant; and 0.1 to 0.5 part by mass of an antioxidant. According to the aluminum foil, the particle size of the aluminum powder is optimized, the three kinds of aluminum powder with different particle sizes are combined for use, the aluminum powder with different particle sizes are in lap joint, the specific pore channel morphology is formed, pore channels are moderate in size and uniform in distribution, the high specific volume of the aluminum foil can be improved, then the bending resistance is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum paste preparation, and particularly relates to an aluminum paste for powder laminated aluminum foil, aluminum foil, and a preparation method. Background Art

[0002] Aluminum electrolytic capacitors are an important electronic component. Their core structure consists of an anodized aluminum foil electrode, an aluminum oxide dielectric layer, and an electrolyte. They have the characteristics of large capacity per unit volume and low cost, and are widely used in power filtering, energy storage and other fields. Among them, porous aluminum foil is the positive electrode substrate of aluminum electrolytic capacitors. The porous structure on the surface increases the specific surface area, thereby increasing the capacitance. In traditional processes, aluminum foil needs to be chemically corroded to form a microscopic uneven surface. However, this method can easily lead to a decrease in the mechanical strength of the aluminum foil, internal stress concentration, and the oxide film is prone to degradation in high temperature and high pressure environments, which in turn affects the life of the capacitor.

[0003] In recent years, aluminum paste sintering has emerged as a new alternative to traditional etching processes. This technology involves applying an aluminum powder paste to the surface of an aluminum foil substrate and then sintering it at high temperatures to form a porous composite structure. This structure retains the high surface area while avoiding the structural fragility associated with chemical corrosion. The core components of aluminum paste include aluminum powder, a binder, a solvent, and various functional additives. The aluminum powder, as a conductive component, has a morphology (flake, spherical, or nanoscale) that directly influences the pore structure of the foil, which in turn affects its specific volume, flex resistance, and service life.

[0004] Existing aluminum pastes have the following limitations. For example, they use a single particle size: most aluminum pastes use aluminum powder with a single particle size, resulting in uneven pore distribution and limited specific volume improvement. Structural defects: The sintered layer formed by the accumulation of traditional spherical aluminum powder is prone to microcracks and fractures when bent, making it difficult to meet the requirements of flexible electronic devices and thus shortening the lifespan of capacitors. Summary of the Invention

[0005] The present disclosure aims to solve at least one of the technical problems existing in the prior art and provides an aluminum paste for powder laminated aluminum foil, an aluminum foil and a preparation method.

[0006] In one aspect of the present disclosure, an aluminum paste for powder laminated aluminum foil is provided.

[0007] include:

[0008] 60-80 parts by mass of aluminum powder; wherein the aluminum powder comprises: a first aluminum powder having a D50 of 1-2 μm, a second aluminum powder having a D50 of 3-4 μm, and a third aluminum powder having a D50 of 6-8 μm;

[0009] 5-10 parts by mass of a binder;

[0010] 15-30 parts by mass of a solvent;

[0011] 0.5-1 parts by mass of leveling agent;

[0012] 0.5-3 parts by mass of a dispersant;

[0013] 0.1-0.5 parts by mass of antioxidant.

[0014] Optionally, the content ratio of the first aluminum powder, the second aluminum powder and the third aluminum powder is 1:(1-3):(1-3).

[0015] Optionally, the first aluminum powder and the second aluminum powder are ball powders, and the third aluminum powder includes ball powders and at least some aluminum flakes.

[0016] Optionally, the aluminum sheet is formed by rolling using a three-roller mill, and the thickness of the aluminum sheet is 3-10 μm.

[0017] Optionally, the cross-section of the aluminum sheet is circular, elliptical, square or polygonal.

[0018] Optionally, the binder comprises polytriphenylamine and modified vinyl alcohol resin; and / or,

[0019] The solvent includes N-methylpyrrolidone and terpineol; and / or,

[0020] The leveling agent is a silicone leveling agent; and / or,

[0021] The dispersant includes sodium alkylbenzene sulfonate and sodium polyacrylate; and / or,

[0022] The antioxidant is at least one of hindered phenols, phosphorus-containing antioxidants and thioesters.

[0023] Optionally, the mass ratio of the polytriphenylamine to the modified vinyl alcohol resin is 1:(8-12); and / or,

[0024] The mass ratio of N-methylpyrrolidone to terpineol is (2-4):1; and / or,

[0025] The mass ratio of the sodium alkylbenzene sulfonate to sodium polyacrylate is (1-3):1.

[0026] In another aspect of the present disclosure, a powder laminated aluminum foil is provided. The powder laminated aluminum foil is formed by sintering the aluminum paste described above.

[0027] Another aspect of the present disclosure provides a method for preparing the powder laminated aluminum foil described above, the method comprising:

[0028] Mix the solvent and dispersant, slowly add aluminum powder, mix evenly, then add binder, leveling agent, and antioxidant, mix evenly to obtain aluminum paste;

[0029] The aluminum paste is coated on one side or both sides of an aluminum foil, dried at 80-120° C. for 10-30 minutes, sintered in an inert atmosphere at 550-650° C. for 10-30 minutes, and slowly cooled to obtain a sintered aluminum foil after chemical formation.

[0030] Optionally, the aluminum paste is applied to one or both sides of the aluminum foil to a wet film thickness of 50-80 μm.

[0031] The present disclosure provides an aluminum paste for powder laminated aluminum foil, aluminum foil and a preparation method. The aluminum paste comprises: 60-80 parts by mass of aluminum powder; wherein the aluminum powder comprises: D50 of 1-2

[0032] The present invention comprises a first aluminum powder having a D50 of 3-4 μm, a second aluminum powder having a D50 of 3-4 μm, and a third aluminum powder having a D50 of 6-8 μm; 5-10 parts by mass of a binder; 15-30 parts by mass of a solvent; 0.5-1 parts by mass of a leveling agent; 0.5-3 parts by mass of a dispersant; and 0.1-0.5 parts by mass of an antioxidant. The present invention optimizes the particle size of the aluminum powder and combines three different particle sizes of aluminum powder. By overlapping the aluminum powders of different particle sizes, a specific pore morphology is formed. The pores are of moderate size and uniform distribution, which helps to increase the high specific volume of the aluminum foil, thereby improving its bending resistance and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flowchart of a method for preparing aluminum paste for powder laminated aluminum foil according to a specific embodiment of the present disclosure;

[0034] Figure 2 This is a scanning electron microscope image of the first aluminum powder of Example 1 of the present disclosure;

[0035] Figure 3 This is a scanning electron microscope image of the second aluminum powder of Example 1 of the present disclosure;

[0036] Figure 4 This is a scanning electron microscope image of the third aluminum powder of Example 1 of the present disclosure; wherein, Figure 4 (A) is the electron microscope image of the third aluminum powder before extrusion. Figure 4 (B) is the electron microscope image of the third aluminum powder after extrusion;

[0037] Figure 5 This is an electron microscope image of the sintered aluminum foil of Example 1 of the present disclosure. DETAILED DESCRIPTION

[0038] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present disclosure and are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present disclosure.

[0039] In one aspect of the present disclosure, an aluminum paste for powder laminated aluminum foil is provided, wherein the aluminum paste comprises: 60-80 parts by mass of aluminum powder; wherein the aluminum powder comprises; D50 is 1-2 μm;

[0040] m first aluminum powder, D50 of 3-4 μm second aluminum powder and D50 of 6-8 μm third aluminum powder; 5-10 parts by mass of a binder; 15-30 parts by mass of a solvent; 0.5-1 parts by mass of a leveling agent; 0.5-3 parts by mass of a dispersant; and 0.1-0.5 parts by mass of an antioxidant.

[0041] In this embodiment, by optimizing the particle size of aluminum powder, three aluminum powders with different particle sizes are used in combination. By overlapping the aluminum powders with different particle sizes, a specific pore morphology is formed. The pores are of moderate size and evenly distributed, which helps to increase the high specific volume of the aluminum foil, thereby improving the bending resistance and increasing the service life.

[0042] In some preferred embodiments, the content ratio of the first aluminum powder, the second aluminum powder and the third aluminum powder is 1:(1-3):(1-3).

[0043] In other preferred embodiments, the first aluminum powder is a ball powder, and its D10 is preferably 0.1-0.5

[0044] μm, D90 is preferably 2.5-4 μm.

[0045] In other preferred embodiments, the second aluminum powder is a ball powder, and its D10 is preferably 0.8-2.5

[0046] μm, D90 is preferably 5-7 μm.

[0047] In other preferred embodiments, the third aluminum powder includes ball powder and at least part of aluminum flakes, and its D10 is preferably 3-5 μm, and its D90 is preferably 9-12 μm.

[0048] As a further preferred solution, the aluminum sheet is formed by rolling on a three-roll mill, and the thickness of the aluminum sheet is 3-10 μm, for example, preferably 4-8 μm. In other words, the third aluminum powder needs to be rolled on a three-roll mill, and part of the aluminum powder is rolled into aluminum sheet.

[0049] As a further preferred solution, the cross-section of the aluminum sheet is circular, elliptical, square or polygonal. Of course, the cross-section of the aluminum sheet can also be other shapes, such as polygonal with sharp edges, etc., and there is no specific limitation on this.

[0050] Furthermore, in other preferred embodiments, the binder includes polytriphenylamine and modified vinyl alcohol resin. The modified vinyl alcohol resin can be one or more of maleic anhydride modified vinyl alcohol resin, acrylic acid modified vinyl alcohol resin, acrylamide modified vinyl alcohol resin, isocyanate modified vinyl alcohol resin, and phenolic epoxy resin modified vinyl alcohol resin. For example, HDI isocyanate modified vinyl alcohol resin can be preferred. By introducing polar groups to cooperate with polytriphenylamine, a network structure is formed to promote the dispersion of aluminum powder, and the pore distribution and morphology of the aluminum paste after sintering are optimized. The mass ratio of polytriphenylamine and the modified vinyl alcohol resin is 1: (8-12). The binder combination and ratio can form a dispersed coordination with aluminum powders of three particle sizes, so that the pores in the sintered layer formed after the aluminum paste is sintered are more uniform and moderate, reducing the local over-sintering phenomenon, improving the high specific volume, optimizing the overlap between aluminum powders, improving the bending resistance, and increasing the service life.

[0051] In other preferred embodiments, the solvent includes N-methylpyrrolidone and terpineol, wherein the mass ratio of N-methylpyrrolidone to terpineol is (2-4):1. The mixture formed by the above solvents has good solubility in the binder and moderate volatility, which is convenient for controlling the drying speed of the aluminum paste and avoiding the generation of bubbles that affect the pore structure after sintering.

[0052] In other preferred embodiments, the leveling agent is a silicone leveling agent, such as BYK-306, which helps to improve coating smoothness.

[0053] In other preferred embodiments, the dispersant includes sodium alkylbenzene sulfonate and sodium polyacrylate, wherein the mass ratio of sodium alkylbenzene sulfonate to sodium polyacrylate is (1-3):1. The mixture formed by the above dispersants is beneficial to inhibiting the agglomeration of aluminum powder and improving the dispersion uniformity.

[0054] In other preferred embodiments, the antioxidant is at least one of hindered phenols, phosphorus-containing antioxidants, and thioesters. Such antioxidants can slow down oxidation during storage and before sintering.

[0055] The present invention achieves high specific volume, high bending resistance, and long service life by combining aluminum powders of different particle sizes and morphologies. Furthermore, the binder and solvent components are designed to further synergize with the aluminum powder to improve its overall performance.

[0056] In another aspect of the present disclosure, a powder-coated aluminum foil is provided. The powder-coated aluminum foil is formed by sintering the aluminum paste described above.

[0057] like Figure 1 As shown, another aspect of the present disclosure provides a method S100 for preparing the powder laminated aluminum foil described above, the method comprising the following steps:

[0058] S110, mixing the solvent and the dispersant, slowly adding the aluminum powder, mixing evenly, then adding the binder, the leveling agent, and the antioxidant, and mixing evenly to obtain the aluminum paste.

[0059] In some preferred embodiments, the solvent is preferably 15-30 parts by mass, and a mixture of N-methylpyrrolidone and terpineol can be used, wherein the mass ratio of N-methylpyrrolidone to terpineol is (2-4):1.

[0060] In other preferred embodiments, the dispersant is preferably 0.5-3 parts by mass, and a mixture of sodium alkylbenzene sulfonate and sodium polyacrylate can be used, wherein the mass ratio of sodium alkylbenzene sulfonate to sodium polyacrylate is (1-3):1.

[0061] In other preferred embodiments, the aluminum powder is preferably 60-80 parts by mass, the aluminum powder particle size is 1-10 μm, and the aluminum powder may preferably include a first aluminum powder, a second aluminum powder and a third aluminum powder with three particle sizes: the D50 of the first aluminum powder is 1-2um; the D50 of the second aluminum powder is 3-4um; and the D50 of the third aluminum powder is 6-8um.

[0062] As a further preferred embodiment, the third aluminum powder includes ball powder and at least a portion of aluminum flakes, wherein D10 is preferably 3-5 μm and D90 is preferably 9-12 μm. The aluminum flakes are formed by rolling on a three-roll mill and have a thickness of 3-10 μm, for example, preferably 4-8 μm.

[0063] In other preferred embodiments, the binder is preferably 5-10 parts by mass, and a mixture of polytriphenylamine and modified vinyl alcohol resin can be used, wherein the mass ratio of polytriphenylamine to the modified vinyl alcohol resin is 1:(8-12). The specific components of the modified vinyl alcohol resin can be referred to the above description.

[0064] In other preferred embodiments, the leveling agent is preferably 0.5-1 parts by mass, and a silicone leveling agent such as BYK-306 can be used.

[0065] In other preferred embodiments, the antioxidant is preferably 0.1-0.5 parts by mass, and one or more of hindered phenols, phosphorus-containing antioxidants, and thioesters are used.

[0066] S120, applying the aluminum paste to one or both sides of an aluminum foil, drying at 80-120° C. for 10-30 minutes, sintering in an inert atmosphere at 550-650° C. for 10-30 minutes, slowly cooling, and obtaining a sintered aluminum foil after chemical formation.

[0067] In some preferred embodiments, the aluminum paste is applied to one or both sides of the aluminum foil to a wet film thickness of 50-80 μm.

[0068] The following is a further description of the preparation method and specific application of aluminum paste for powder laminated aluminum foil with reference to specific examples:

[0069] Example 1

[0070] The aluminum paste component formula of this example includes 70 parts by mass of aluminum powder, 10 parts by mass of binder, 18 parts by mass of solvent, 0.7 parts by mass of leveling agent, 1 part by mass of dispersant, and 0.3 parts by mass of antioxidant. Please refer to Table 1 for details.

[0071] Further referring to Table 1, the binder comprises 1 part by mass of polytriphenylamine and 9 parts by mass of modified vinyl alcohol resin. The modified vinyl alcohol resin is HDI isocyanate-modified vinyl alcohol resin. The solvent comprises 14 parts by mass of N-methylpyrrolidone and 4 parts by mass of terpineol. BYK-306 is used as the leveling agent. The dispersant comprises a mixture of 0.6 parts by mass of sodium alkylbenzene sulfonate and 0.4 parts by mass of sodium polyacrylate. The antioxidant is phosphorus-containing L-20.

[0072] Further referring to Table 2, the aluminum powder includes the first aluminum powder, the second aluminum powder and the third aluminum powder of different particle sizes, and the content ratio of the three is 1:1:2. Figure 2 As shown, the average particle size of the first aluminum powder is 1-2 μm, with D10 = 0.25 μm, D50 = 1.46 μm, and D90 = 3.68 μm. Figure 3 As shown, the average particle size of the second aluminum powder is 3-4 μm, with D10 = 0.86 μm, D50 = 3.64 μm, and D90 = 6.25 μm. Figure 4 As shown, the average particle size of the third aluminum powder before extrusion is 6-8μm, and the average particle size after extrusion is also 6-8μm, with D10=3.69μm, D50=7.84μm, and D90=9.86μm. It contains 5% aluminum flake powder, and is rolled by a three-roll mill. Under the combined action of the pressure of the three-roll mill and the surrounding aluminum powder, the cross-section of the aluminum sheet after rolling is a polygon with sharp edges.

[0073] Furthermore, the aluminum foil is prepared by the following method, comprising:

[0074] The above solvent and dispersant are mixed, aluminum powder is slowly added, mixed evenly, and then a binder, a leveling agent, and an antioxidant are added and mixed evenly to obtain aluminum paste.

[0075] The aluminum paste is coated on one side or both sides of an aluminum foil, dried at 100° C. for 15 minutes, sintered at 600° C. in an inert atmosphere for 20 minutes, and slowly cooled to obtain a sintered aluminum foil after chemical formation.

[0076] like Figure 5 As shown, the middle is the aluminum substrate, and the two sides are aluminum paste sintered layers, with a specific capacity of 1.07μF / cm 2 , resistant to bending 102 times, and the tensile strength after sintering is 25MPa.

[0077] Example 2

[0078] As shown in Table 1, the aluminum paste formula of this example is the same as that of Example 1, except that the particle sizes of the second aluminum powder and the third aluminum powder are different. As shown in Table 2, the second aluminum powder has D10 = 0.71 μm, D50 = 3.62 μm, and D90 = 6.86 μm, and the third aluminum powder has D10 = 3.64 μm, D50 = 7.22 μm, and D90 = 9.02 μm, and contains 5% aluminum flake powder.

[0079] Furthermore, a sintered aluminum foil was prepared by the same method as in Example 1, and its specific capacity was 1.04 μF / cm 2 , resistant to bending 99 times, and the tensile strength after sintering is 25MPa.

[0080] Example 3

[0081] As shown in Table 1, the aluminum paste formula of this example is the same as that of Example 1, except that the particle sizes of the first aluminum powder and the third aluminum powder are different. As shown in Table 2, the first aluminum powder has D10 = 0.48 μm, D50 = 1.96 μm, and D90 = 4.36 μm, and the third aluminum powder has D10 = 3.65 μm, D50 = 7.41 μm, and D90 = 9.46 μm, and contains 5% aluminum flake powder.

[0082] Furthermore, a sintered aluminum foil was prepared by the same method as in Example 1, and its specific capacity was 1.06 μF / cm 2 , resistant to bending 101 times, and the tensile strength after sintering is 25MPa.

[0083] Comparative Example 1

[0084] As shown in Table 1, the aluminum paste formula of this example is the same as that of Example 1, except that the third aluminum powder is not added, and only the first aluminum powder and the second aluminum powder are included.

[0085] Furthermore, a sintered aluminum foil was prepared by the same method as in Example 1, and its specific capacity was 0.95 μF / cm 2 , 84 bending times, and the tensile strength after sintering is 18 MPa. Compared with Examples 1-3, the specific capacity, bending times and tensile strength are all reduced.

[0086] Comparative Example 2

[0087] As shown in Table 1, the aluminum paste formula of this example is the same as that of Example 1, except that the third aluminum powder is not extruded and there is no flaky aluminum powder.

[0088] Furthermore, a sintered aluminum foil was prepared by the same method as in Example 1, and its specific capacity was 0.98 μF / cm 2 , 85 bending times, and the tensile strength after sintering is 18 MPa. Compared with Examples 1-3, the specific capacity, bending times and tensile strength are all reduced.

[0089] Comparative Example 3

[0090] As shown in Table 1, the aluminum paste formula of this example is the same as that of Example 1, except that the binder is 10 parts by mass of modified vinyl alcohol resin, which is also HDI isocyanate-modified vinyl alcohol resin.

[0091] Furthermore, a sintered aluminum foil was prepared by the same method as in Example 1, and its specific capacity was 0.99 μF / cm 2 , 90 bending times, and the tensile strength after sintering is 19 MPa. Compared with Examples 1-3, the specific capacity, bending times and tensile strength are all reduced.

[0092] Table 1 Formulations of aluminum pastes in various embodiments and comparative examples

[0093]

[0094] Table 2 Aluminum powder parameters of each embodiment and comparative example

[0095]

[0096]

[0097] The present disclosure provides an aluminum paste for powder laminated aluminum foil, an aluminum foil, and a preparation method thereof, which have the following beneficial effects compared to the prior art:

[0098] First, the present disclosure uses aluminum powders of different particle sizes and shapes to make the aluminum foil have high specific volume, high bending resistance and long service life;

[0099] Second, the present disclosure further improves the comprehensive performance of aluminum foil by optimizing the binder, solvent components, etc., and synergizing with aluminum powder.

[0100] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. An aluminum paste for powder laminated aluminum foil, characterized in that: The aluminum paste comprises: 60-80 parts by mass of aluminum powder; wherein the aluminum powder comprises: a first aluminum powder having a D50 of 1-2 μm, a second aluminum powder having a D50 of 3-4 μm, and a third aluminum powder having a D50 of 6-8 μm; 5-10 parts by mass of a binder; 15-30 parts by mass of a solvent; 0.5-1 parts by mass of leveling agent; 0.5-3 parts by mass of a dispersant; 0.1-0.5 parts by mass of antioxidant.

2. The aluminum paste according to claim 1, characterized in that The content ratio of the first aluminum powder, the second aluminum powder and the third aluminum powder is 1:(1-3):(1-3).

3. The aluminum paste according to claim 1, characterized in that The first aluminum powder and the second aluminum powder are ball powders, and the third aluminum powder includes ball powders and at least some aluminum flakes.

4. The aluminum paste according to claim 3, characterized in that The aluminum sheet is formed by rolling with a three-roller machine, and the thickness of the aluminum sheet is 3-10 μm.

5. The aluminum paste according to claim 4, characterized in that The cross-section of the aluminum sheet is in the shape of a circle, an ellipse, a square or a polygon.

6. The aluminum paste according to claim 1, characterized in that The binder comprises polytriphenylamine and modified vinyl alcohol resin; and / or, The solvent includes N-methylpyrrolidone and terpineol; and / or, The leveling agent is a silicone leveling agent; and / or, The dispersant includes sodium alkylbenzene sulfonate and sodium polyacrylate; and / or, The antioxidant is at least one of hindered phenols, phosphorus-containing antioxidants and thioesters.

7. The aluminum paste according to claim 6, characterized in that The mass ratio of the polytriphenylamine to the modified vinyl alcohol resin is 1:(8-12); and / or, The mass ratio of N-methylpyrrolidone to terpineol is (2-4):1; and / or, The mass ratio of the sodium alkylbenzene sulfonate to sodium polyacrylate is (1-3):

1.

8. A powder-laminated aluminum foil, characterized in that The powder laminated aluminum foil is formed by sintering the aluminum paste according to any one of claims 1 to 7.

9. A method for preparing the powder-laminated aluminum foil according to claim 8, characterized in that: The method comprises: Mix the solvent and dispersant, slowly add aluminum powder, mix evenly, then add binder, leveling agent, and antioxidant, mix evenly to obtain aluminum paste; The aluminum paste is coated on one side or both sides of an aluminum foil, dried at 80-120° C. for 10-30 minutes, sintered in an inert atmosphere at 550-650° C. for 10-30 minutes, and slowly cooled to obtain a sintered aluminum foil after chemical formation.

10. The method according to claim 9, characterized in that The aluminum paste is applied to one or both sides of the aluminum foil to a wet film thickness of 50-80 μm.

Images