Carboxymethyl starch-based electrolytic copper powder compound dispersant and preparation method thereof

Abstract

The application provides a carboxymethyl starch-based electrolytic copper powder compound dispersant and a preparation method thereof, which comprises a core layer coordination component, a shell layer skeleton component and an additive; the core layer coordination component is triethanolamine; the shell layer skeleton component is carboxymethyl modified corn starch; the degree of substitution DS of the carboxymethyl modified corn starch is 0.35-0.85; and the additive is PEG-6000. The carboxymethyl modified corn starch with a specific degree of substitution is compounded with triethanolamine and PEG-6000 to prepare a dispersant, which is suitable for an alkaline electrolytic copper powder system with a pH of 9.0-10.5. Through the synergistic effect of coordination adsorption, steric hindrance and interface regulation, the secondary agglomeration and surface oxidation of the copper powder in the electrolysis process can be effectively inhibited, so that superfine copper powder with a particle size D50 of 2-3 microns, a narrow particle size distribution and an oxygen content of less than or equal to 0.2wt% is prepared. The dispersant has good alkali resistance stability, high utilization rate and is suitable for industrialized production and application.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper powder preparation technology, and relates to a carboxymethyl starch-based electrolytic copper powder compound dispersant and its preparation method. Background Technology

[0002] Electrolytic copper powder, due to its high purity, controllable particle size, and good formability, is widely used in powder metallurgy, conductive pastes, electromagnetic shielding, and catalysts. With downstream applications increasingly demanding higher fineness, uniformity, and oxidation resistance in copper powder, how to achieve ultrafine, low-oxygen preparation of copper powder through dispersant regulation during electrolysis has become a key research focus in this field. During electrolytic powder preparation, the dispersant, by adsorbing onto the surface of the newly formed copper powder, inhibits particle collision and agglomeration and surface oxidation, directly determining the particle size distribution, morphology, and oxygen content of the product.

[0003] In existing electrolytic copper powder dispersion technologies, one type mainly uses acidic mineral slurry electrolysis systems, typically employing a binary dispersant composed of triethanolamine and animal glue (industrial gelatin). This system is only suitable for strongly acidic mineral slurry environments. When applied to weakly alkaline pure salt electrolysis systems with a pH of 9.0~10.5, animal glue, as a protein-based polymer, undergoes peptide bond hydrolysis, molecular chain degradation and denaturation, and its steric hindrance effect rapidly diminishes, leading to a significant decrease in dispersion stability. The newly formed copper powder is prone to secondary agglomeration and uneven morphology. At the same time, the increased contact between the copper surface and the electrolyte results in higher oxygen content and large fluctuations in bulk density, failing to meet the requirements for preparing ultrafine, high-grade copper powder.

[0004] In addition, existing compound dispersants in other fields are mostly designed for scenarios such as solvothermal synthesis and slurry grinding. Their components and mechanisms of action cannot be adapted to the dynamic cathodic deposition process of electrolytic copper powder. There is a lack of ternary compound dispersion systems specifically optimized for the process window of alkaline electrolytic copper powder, making it difficult to simultaneously achieve multiple performance goals such as fine particle size, narrow distribution and low oxygen content.

[0005] Therefore, developing a special compound dispersant with good alkali resistance, strong dispersion stability, and the ability to simultaneously control the particle size and oxygen content of copper powder is a technical problem that urgently needs to be solved in the preparation of ultrafine low-oxygen copper powder by alkaline electrolysis. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a carboxymethyl starch-based electrolytic copper powder compound dispersant and its preparation method. The carboxymethyl starch-based electrolytic copper powder compound dispersant provided by the present invention is suitable for alkaline electrolytic copper powder systems with a pH of 9.0~10.5. Through the synergistic effect of coordination adsorption, steric hindrance, and interface regulation, it can effectively inhibit secondary agglomeration and surface oxidation of copper powder during electrolysis, resulting in ultrafine copper powder with a particle size D50 of 2μm~3μm, narrow particle size distribution, and oxygen content ≤0.2wt%. The dispersant exhibits good alkali resistance and high utilization rate, making it suitable for industrial production applications.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, wherein the carboxymethyl starch-based electrolytic copper powder compound dispersant comprises a core layer coordination component, a shell layer framework component, and an auxiliary agent;

[0009] The core layer coordination component is triethanolamine;

[0010] The shell skeleton component is carboxymethyl modified corn starch; the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.35~0.85.

[0011] The additive is PEG-6000.

[0012] This invention employs a compound dispersant consisting of triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution, and PEG-6000, adapted to an alkaline electrolytic copper powder system with a pH of 9.0~10.5. Through the synergistic effect of coordination adsorption, steric hindrance, and interface regulation, secondary agglomeration and surface oxidation of copper powder during electrolysis can be effectively suppressed, resulting in ultrafine copper powder with a particle size D50 of 2μm~3μm, narrow particle size distribution, and oxygen content ≤0.2wt%. The dispersant exhibits good alkali resistance and high utilization rate, making it suitable for industrial production applications.

[0013] In some embodiments, the mass ratio of triethanolamine to carboxymethyl modified corn starch is 3.5:1 to 4.5:1.

[0014] In some embodiments, the amount of PEG-6000 used is 0.5wt% to 2wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0015] In some embodiments, the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.5 to 0.7.

[0016] Secondly, the present invention provides a method for preparing a carboxymethyl starch-based electrolytic copper powder compound dispersant, the preparation method comprising the following steps:

[0017] (1) Carboxymethyl modified corn starch was dissolved in deionized water to obtain starch mother liquor;

[0018] (2) Mix triethanolamine and starch mother liquor from step (1) according to the formula amount, and then mix with PEG-6000. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0019] In some embodiments, the temperature of the deionized water in step (1) is 50°C to 60°C.

[0020] In some embodiments, the mass fraction of the starch mother liquor in step (1) is 5wt% to 10wt%.

[0021] In some embodiments, the mixing temperature of the triethanolamine and the starch mother liquor is 40°C to 50°C.

[0022] In some embodiments, the temperature at which the PEG-6000 is remixed is 40°C to 50°C.

[0023] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0024] (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at a temperature of 50℃~60℃ to obtain a starch mother liquor with a mass fraction of 5wt%~10wt%.

[0025] (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 40℃~50℃, and then PEG-6000 is mixed at 40℃~50℃. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0026] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention employs a compound dispersant consisting of triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution, and PEG-6000, adapted to an alkaline electrolytic copper powder system with a pH of 9.0~10.5. Through the synergistic effect of coordination adsorption, steric hindrance, and interface regulation, secondary agglomeration and surface oxidation of copper powder during electrolysis can be effectively suppressed, resulting in ultrafine copper powder with a particle size D50 of 2μm~3μm, narrow particle size distribution, and oxygen content ≤0.2wt%. The dispersant exhibits good alkali resistance and high utilization rate, making it suitable for industrial production applications. Detailed Implementation

[0029] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0030] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0031] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0032] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0033] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0034] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0036] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0037] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0038] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0039] In a first aspect, the present invention provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, wherein the carboxymethyl starch-based electrolytic copper powder compound dispersant comprises a core layer coordination component, a shell layer framework component, and an auxiliary agent;

[0040] The core layer coordination component is triethanolamine;

[0041] The shell skeleton component is carboxymethyl modified corn starch; the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.35~0.85, for example, it can be 0.35, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.85, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable;

[0042] The additive is PEG-6000.

[0043] This invention employs a compound dispersant consisting of triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution, and PEG-6000, adapted to an alkaline electrolytic copper powder system with a pH of 9.0~10.5. Through the synergistic effect of coordination adsorption, steric hindrance, and interface regulation, secondary agglomeration and surface oxidation of copper powder during electrolysis can be effectively suppressed, resulting in ultrafine copper powder with a particle size D50 of 2μm~3μm, narrow particle size distribution, and oxygen content ≤0.2wt%. The dispersant exhibits good alkali resistance and high utilization rate, making it suitable for industrial production applications.

[0044] Specifically, carboxymethyl modified corn starch replaces traditional animal glue as the steric hindrance framework. Its molecular structure remains stable in a weakly alkaline electrolyte with a pH of 9.0~10.5 for a long time without hydrolytic degradation, solving the problem of protein dispersants being prone to failure in alkaline environments and improving process stability and dispersant utilization. Triethanolamine is firmly adsorbed on the surface of nascent copper powder through coordination bonds as a core anchoring point. The carboxymethyl starch molecular chains fully swell and extend to form a shell barrier. Combined with PEG-6000 to reduce interfacial tension and promote uniform extension of starch chains, the core-shell double-layer structure constructed by the three has the advantages of strong adsorption and high steric hindrance, which can effectively inhibit the collision, aggregation and coarsening of copper particles. The carboxymethyl starch-based electrolytic copper powder compound dispersant can form a dense adsorption protective layer on the surface of copper powder, physically isolating the nascent highly active copper surface from direct contact with the electrolyte and air. At the same time, the coordination effect of triethanolamine can passivate the oxidation active sites on the copper surface. Under the dual effect, the oxygen content of copper powder is controlled below 0.2wt%.

[0045] In this invention, the degree of substitution (DS) refers to the average number of carboxyl groups substituted by carboxyl groups on each glucose unit of a corn starch molecule. A lower DS indicates fewer carboxyl groups, resulting in poorer starch water solubility, poor molecular expansion in alkaline electrolytes, and weaker steric hindrance. Conversely, a higher DS indicates excessively high starch water solubility, overly loose molecular chains, insufficient film strength adsorbed on the copper powder surface, and reduced ability to block oxidation and prevent aggregation. A suitable DS value allows the carboxyl-modified corn starch to be completely soluble in a weakly alkaline electrolyte, with fully extended molecular chains forming a 3D barrier, while also stably adsorbing copper particles, thus meeting the dispersion requirements of alkaline electrolytic copper powder. In some embodiments, the degree of substitution (DS) of the carboxyl-modified corn starch is 0.5~0.7.

[0046] In some embodiments, the mass ratio of triethanolamine to carboxymethyl modified corn starch is 3.5:1 to 4.5:1, for example, it can be 3.5:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1 or 4.5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] In some embodiments, the amount of PEG-6000 is 0.5wt% to 2wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant, for example, it can be 0.5wt%, 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.6wt%, 1.8wt% or 2wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] Secondly, the present invention provides a method for preparing a carboxymethyl starch-based electrolytic copper powder compound dispersant, the preparation method comprising the following steps:

[0049] (1) Carboxymethyl modified corn starch was dissolved in deionized water to obtain starch mother liquor;

[0050] (2) Mix triethanolamine and starch mother liquor from step (1) according to the formula amount, and then mix with PEG-6000. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0051] In some embodiments, the temperature of the deionized water in step (1) is 50°C to 60°C, for example, it can be 50°C, 52°C, 54°C, 55°C, 56°C, 58°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] If the temperature of deionized water is below 50℃, the carboxymethyl starch absorbs water and swells slowly, and the starch particles cannot be completely dissociated and expanded, resulting in a defective steric barrier and poorer copper powder particle size and antioxidant properties. If the temperature of deionized water is above 60℃, it will cause high-temperature degradation of the carboxymethyl starch molecular chain, loss of hydrophilic groups, and a decrease in alkali resistance stability in alkaline electrolyte.

[0053] In some embodiments, the mass fraction of the starch mother liquor in step (1) is 5wt% to 10wt%, for example, it can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] When the starch mother liquor mass fraction is below 5 wt%, the content of carboxymethyl starch, a key component of the system, is insufficient. This leads to a decrease in the adsorption density of diluted triethanolamine, making it difficult to form a complete three-dimensional barrier layer. Copper powder is prone to agglomeration, oxygen content increases, and solvent consumption per unit of production capacity is high, resulting in higher production costs. Conversely, when the starch mother liquor mass fraction exceeds 10 wt%, the slurry viscosity increases, causing starch molecules to entangle and agglomerate, hindering their expansion. Furthermore, the mixing of triethanolamine and PEG-6000 becomes uneven.

[0055] In some embodiments, the mixing temperature of the triethanolamine and the starch mother liquor is 40°C to 50°C, for example, 40°C, 42°C, 44°C, 45°C, 46°C, 48°C or 50°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] When the mixing temperature is below 40℃, the molecular motion rate is low, and triethanolamine is difficult to bind evenly to the starch molecular chain. Some copper particles in the electrolyte lack passivation sites, and the oxygen content of the finished product increases. When the temperature is above 50℃, triethanolamine will volatilize and be lost, while accelerating the thermal degradation of starch and weakening the dispersion and antioxidant effects.

[0057] In some embodiments, the temperature at which the PEG-6000 is remixed is 40°C to 50°C, for example, 40°C, 42°C, 44°C, 45°C, 46°C, 48°C or 50°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0059] (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at a temperature of 50℃~60℃ to obtain a starch mother liquor with a mass fraction of 5wt%~10wt%;

[0060] (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 40℃~50℃, and then PEG-6000 is mixed at 40℃~50℃. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0061] Optionally, the application of the carboxymethyl starch-based electrolytic copper powder compound dispersant of the present invention includes: adding the carboxymethyl starch-based electrolytic copper powder compound dispersant to an alkaline copper electrolyte with a pH value of 9 to 10.5, wherein the amount of carboxymethyl starch-based electrolytic copper powder compound dispersant added is 50 mg / L to 150 mg / L.

[0062] Optionally, the alkaline copper electrolyte includes copper sulfate, borax, and sodium sulfate. Specifically, the copper ion content in the alkaline copper electrolyte is 10 g / L to 20 g / L, the borax content is 20 g / L to 35 g / L, and the sodium sulfate content is 30 g / L to 50 g / L.

[0063] Optionally, the current density for electrolyzing the alkaline copper electrolyte is 150 A / m. 2 ~300A / m 2 The temperature is 40℃~60℃, and the distance between the anode and cathode plates is 4cm~6cm.

[0064] Example 1

[0065] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, comprising carboxymethyl modified corn starch with a degree of substitution (DS) of 0.6, triethanolamine, and PEG-6000;

[0066] The mass ratio of triethanolamine to carboxymethyl modified corn starch is 4:1; the amount of PEG-6000 used is 4 wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0067] The preparation method of the carboxymethyl starch-based electrolytic copper powder compound dispersant in this embodiment includes:

[0068] (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at 55°C to obtain a starch mother liquor with a mass fraction of 8wt%.

[0069] (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 45°C, and then mixed with PEG-6000 according to the formula amount at 45°C. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0070] Example 2

[0071] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, comprising carboxymethyl modified corn starch with a degree of substitution (DS) of 0.6, triethanolamine, and PEG-6000;

[0072] The mass ratio of triethanolamine to carboxymethyl modified corn starch is 3.5:1; the amount of PEG-6000 used is 0.5 wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0073] The preparation method of the carboxymethyl starch-based electrolytic copper powder compound dispersant in this embodiment includes:

[0074] (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at 50°C to obtain a starch mother liquor with a mass fraction of 5wt%.

[0075] (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 40°C, and then mixed with PEG-6000 according to the formula amount at 40°C. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0076] Example 3

[0077] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, comprising carboxymethyl modified corn starch with a degree of substitution (DS) of 0.6, triethanolamine, and PEG-6000;

[0078] The mass ratio of triethanolamine to carboxymethyl modified corn starch is 4.5:1; the amount of PEG-6000 used is 2 wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0079] The preparation method of the carboxymethyl starch-based electrolytic copper powder compound dispersant in this embodiment includes:

[0080] (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at 60°C to obtain a starch mother liquor with a mass fraction of 10wt%.

[0081] (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 50°C, and then mixed with PEG-6000 according to the formula amount at 50°C. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

[0082] Example 4

[0083] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.5.

[0084] Example 5

[0085] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.7.

[0086] Example 6

[0087] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.35.

[0088] Example 7

[0089] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.85.

[0090] Example 8

[0091] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the mass ratio of triethanolamine to carboxymethyl modified corn starch is 2:1.

[0092] Example 9

[0093] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the mass ratio of triethanolamine to carboxymethyl modified corn starch is 6:1.

[0094] Example 10

[0095] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant. Except that the amount of PEG-6000 is 0.2 wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant, the rest is the same as in Example 1.

[0096] Example 11

[0097] This embodiment provides a carboxymethyl starch-based electrolytic copper powder compound dispersant. Except that the amount of PEG-6000 is 3wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant, the rest is the same as in Example 1.

[0098] Comparative Example 1

[0099] This comparative example provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as Example 1 except that it does not contain triethanolamine.

[0100] Comparative Example 2

[0101] This comparative example provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as Example 1 except that it does not contain PEG-6000.

[0102] Comparative Example 3

[0103] This comparative example provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.2.

[0104] Comparative Example 4

[0105] This comparative example provides a carboxymethyl starch-based electrolytic copper powder compound dispersant, which is the same as in Example 1 except that the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.9.

[0106] Performance Characterization

[0107] The alkaline copper electrolyte of this invention uses copper sulfate pentahydrate to provide copper ions, with a reference copper ion concentration controlled at 15 g / L; borax is used as a pH buffer at a concentration of 25 g / L; sodium sulfate is used as a conductive supporting electrolyte at a concentration of 40 g / L, and the overall pH is adjusted to a stable 9.8 using alkali. Adding 100 mg of the carboxymethyl starch-based electrolytic copper powder compound dispersant from the above examples and comparative examples to the alkaline copper electrolyte, the current density for electrolyzing the alkaline copper electrolyte is 200 A / m. 2 The temperature was 50℃ and the distance between the anode and cathode plates was 5cm. The median particle size D50, particle size span, and oxygen content of the obtained copper powder were measured, and the results are shown in Table 1.

[0108] Among them, the median particle size D50 and the particle size span were determined by a laser particle size analyzer, and span = (D90-D10) / D50; the dried copper powder samples were tested by an infrared oxygen analyzer to directly determine the total oxygen content of the powder. All test samples were electrolytic copper powders that had been washed with pure water and thoroughly dried after electrolysis.

[0109] Table 1

[0110]

[0111] As can be seen from Examples 1 to 5 in Table 1, the present invention uses triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution (DS=0.5~0.7) and PEG-6000 to prepare copper powder with a particle size D50 of 2μm~3μm, a narrow particle size distribution (span<1.0) and an oxygen content ≤0.2wt% by combining triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution (DS=0.5~0.7) and PEG-6000. Through the synergistic effect of coordination adsorption, steric hindrance and interface regulation, the copper powder prepared has a particle size D50 of 2μm~3μm, a narrow particle size distribution (span<1.0) and an oxygen content ≤0.2wt%.

[0112] A comparison of Examples 8, 9, and 1 shows that when the ratio is 2:1 (Example 8), the coordination anchoring component is insufficient, the starch shell cannot be firmly bonded to the copper powder surface, and the steric hindrance protection effect is weakened; when the ratio is 6:1 (Example 9), the oxygen content rises to 0.23%. This indicates that deviating from the optimal ratio range will damage the assembly integrity of the core-shell structure and cannot simultaneously achieve dispersion and oxidation resistance.

[0113] A comparison of Examples 10, 11 and Example 1 shows that when the amount of PEG-6000 is as low as 0.2wt% (Example 10), the interfacial tension regulation ability is insufficient, the starch chain extension is hindered, and the synergistic effect is not sufficient; when the amount of PEG-6000 is as high as 3wt% (Example 11), the overall hydrophilicity of the dispersant is too strong. Although it can maintain D50 at 2.9μm, the hydration and swelling of the protective layer is intensified, and the oxygen barrier ability is weakened.

[0114] A comparison of Comparative Examples 1 and 2 with Example 1 shows that, in the absence of triethanolamine (Comparative Example 1), coordination anchoring points cannot be established on the surface of the copper powder, and the starch and PEG cannot form a stable core-shell adsorption layer. The copper powder exhibits severe agglomeration, with a D50 as high as 5.6 μm and an oxygen content of 0.45%. In the absence of PEG-6000 (Comparative Example 2), the binary system of triethanolamine and starch cannot fully extend the starch chains, resulting in suboptimal steric hindrance. The D50 is 3.3 μm, and the oxygen content is 0.26%, both failing to meet the technical requirements.

[0115] Comparison of Comparative Examples 3 and 4 with Example 1 shows that when DS=0.2 (Comparative Example 3), the starch hardly swelled and lost its steric function, with a D50 as high as 4.3 μm and an oxygen content of 0.34%; when DS=0.9 (Comparative Example 4), although the D50 was 2.8 μm, the excessive carboxymethyl content led to excessive hydration of the shell and a loose structure, with an oxygen content of 0.28%, exceeding the standard of 0.2 wt%.

[0116] In summary, this invention utilizes a compound dispersant of triethanolamine, carboxymethyl modified corn starch with a specific degree of substitution, and PEG-6000, adapted to an alkaline electrolytic copper powder system with a pH of 9.0–10.5. Through the synergistic effect of coordination adsorption, steric hindrance, and interface regulation, secondary agglomeration and surface oxidation of copper powder during electrolysis can be effectively suppressed, resulting in ultrafine copper powder with a particle size D50 of 2–3 μm, narrow particle size distribution, and oxygen content ≤0.2 wt%. The dispersant exhibits good alkali resistance and high utilization rate, making it suitable for industrial production applications. Specifically, by using carboxymethyl modified corn starch instead of traditional animal glue as the steric hindrance framework, its molecular structure remains stable for a long time in a weakly alkaline electrolyte with a pH of 9.0–10.5, without hydrolytic degradation. This solves the problem of protein dispersants easily failing in alkaline environments, improving process stability and dispersant utilization rate. Triethanolamine is firmly adsorbed onto the surface of newly formed copper powder via coordination bonds, serving as a core anchoring point. Carboxymethyl starch molecular chains fully swell and extend to form a shell barrier. Combined with PEG-6000 to reduce interfacial tension and promote uniform extension of starch chains, the core-shell bilayer structure constructed by these three components has the advantages of strong adsorption and high steric hindrance, which can effectively inhibit the collision, aggregation, and coarsening of copper particles. The carboxymethyl starch-based electrolytic copper powder compound dispersant can form a dense adsorption protective layer on the surface of the copper powder, physically isolating the newly formed highly active copper surface from direct contact with the electrolyte and air. At the same time, the coordination effect of triethanolamine can passivate the oxidation active sites on the copper surface. Under the dual effect, the oxygen content of the copper powder is controlled below 0.2 wt%.

[0117] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A carboxymethyl starch-based electrolytic copper powder compound dispersant, characterized in that, The carboxymethyl starch-based electrolytic copper powder compound dispersant includes a core coordination component, a shell framework component, and additives. The core layer coordination component is triethanolamine; The shell skeleton component is carboxymethyl modified corn starch; the degree of substitution (DS) of the carboxymethyl modified corn starch is 0.35~0.

85. The additive is PEG-6000.

2. The carboxymethyl starch-based electrolytic copper powder compound dispersant according to claim 1, characterized in that, The mass ratio of triethanolamine to carboxymethyl modified corn starch is 3.5:1 to 4.5:

1.

3. The carboxymethyl starch-based electrolytic copper powder compound dispersant according to claim 1 or 2, characterized in that, The amount of PEG-6000 used is 0.5wt% to 2wt% of the total mass of the carboxymethyl starch-based electrolytic copper powder compound dispersant.

4. The carboxymethyl starch-based electrolytic copper powder compound dispersant according to any one of claims 1 to 3, characterized in that, The degree of substitution (DS) of the carboxymethyl modified corn starch is 0.5~0.

7.

5. A method for preparing a carboxymethyl starch-based electrolytic copper powder compound dispersant, characterized in that, The preparation method includes the following steps: (1) Carboxymethyl modified corn starch was dissolved in deionized water to obtain starch mother liquor; (2) Mix triethanolamine and starch mother liquor from step (1) according to the formula amount, and then mix with PEG-6000. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

6. The preparation method according to claim 5, characterized in that, The temperature of the deionized water in step (1) is 50℃~60℃.

7. The preparation method according to claim 5 or 6, characterized in that, The mass fraction of the starch mother liquor in step (1) is 5wt%~10wt%.

8. The preparation method according to any one of claims 5 to 7, characterized in that, The mixing temperature of the triethanolamine and the starch mother liquor is 40℃~50℃.

9. The preparation method according to any one of claims 5 to 8, characterized in that, The temperature at which the mixture is further mixed with PEG-6000 is 40℃~50℃.

10. The preparation method according to claim 5, characterized in that, The preparation method includes the following steps: (1) Carboxymethyl modified corn starch was completely swollen and dissolved in deionized water at a temperature of 50℃~60℃ to obtain a starch mother liquor with a mass fraction of 5wt%~10wt%; (2) According to the formula amount, triethanolamine and starch mother liquor from step (1) are mixed at 40℃~50℃, and then PEG-6000 is mixed at 40℃~50℃. The resulting mixture is dried to obtain the carboxymethyl starch-based electrolytic copper powder compound dispersant.

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