Conductive silver paste based on graphene and preparation method thereof

Abstract

The invention discloses conductive silver paste based on graphene and a preparation method of the conductive silver paste. The invention discloses conductive silver paste based on graphene. The conductive silver paste is prepared from the following raw materials in percentage by weight: 40-50% of graphene, 10-20% of silver particles, 0.5-1.5% of a polymeric dispersant, 1-2% of potassium ferrocyanide, 25-35% of blended resin and 10-15% of dibasic acid dimethyl ester. The graphene-based conductive silver paste is prepared by grinding and processing materials such as graphene, the polymeric dispersant, potassium ferrocyanide, blended resin, dibasic acid dimethyl ester, silver particles and the like for multiple times, a solvent can be released in a low-temperature dry-curing (70-120 DEG C) environment, and a binder (resin) is dry-cured, so that the graphene-based conductive silver paste has good conductivity; the graphene-based conductive silver paste can be better attached to different types of base materials, and has adhesiveness and oxidation resistance; the stable conductive performance can be kept in the production manufacturing and long-term use process, and the service life of the product can be prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of slurries, and in particular to a formula and a preparation method of a graphene-based conductive silver slurry. Background Art

[0002] The research and application of conductive silver pastes still present numerous technical challenges and difficulties. Conductive performance is the most important property of conductive silver pastes. The content of precious metals, such as silver and gold powder, and the stability of the paste have a direct impact on conductivity. Furthermore, precious metals like silver and gold are expensive (especially silver, which accounts for over 60% of the cost of conductive silver paste), significantly increasing the cost of end products. Precious metal reserves are limited, and the supply chain is susceptible to international price fluctuations. Furthermore, in industries requiring frequent water washing, careful selection of the appropriate silver powder content is crucial. Due to the interaction between silver powder and the binder, dispersion of silver powder in the paste is often a critical issue. Failure to evenly disperse the silver powder in low-temperature conductive pastes can lead to inconsistent conductivity, impacting the performance of electronic components. The small particle size of the silver powder in the paste creates the risk of agglomeration, which directly impacts the paste's conductivity and stability. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention provides a graphene-based conductive silver paste. The improved preparation method and composition of this paste effectively address the aforementioned issues, providing a more stable, high-performance, and low-cost graphene-based conductive silver paste. This presents a promising future for the research and application of conductive silver pastes. This paste can replace pure silver particle conductive silver paste in the production of conductive, thermal, and heating products, significantly reducing raw material production costs. (Under equivalent electrical performance requirements, this product offers a 30%-50% reduction in cost compared to pure silver particle paste.)

[0004] The technical problem to be solved by the present invention is achieved through the following technical solutions: A graphene-based conductive silver paste is composed of the following raw materials by weight: 40-50% graphene, 10-20% silver particles, 0.5-1.5% polymer dispersant, 1-2% potassium ferrocyanide, 25-35% formulation resin, and 10-15% dimethyl dibasic acid.

[0005] Preferably, the formulated resin is composed of the following raw materials by weight: 18-25% chloroacetic acid resin, 5-15% polyurethane 6041, 60-70% isophorone and 2-7% dimethyl dibasic acid.

[0006] Preferably, the chlorovinyl resin is composed of vinyl chloride, vinyl acetate, and vinyl alcohol. The chlorovinyl resin material used, along with a special production process, can exhibit excellent compatibility with polyurethane, high toughness, and plasticity. The chlorovinyl resin can be added to a graphene-based conductive silver paste to increase the paste's viscosity and improve the dispersibility of the conductive material. This ensures that the graphene and silver particles are evenly dispersed in the paste, providing excellent coating compatibility, high toughness, and plasticity.

[0007] Preferably, the polyurethane 6041 is a polymeric material characterized by durability, elasticity, and stability. It is added to the slurry to improve its viscosity, dispersibility, durability, elasticity, and coating properties. The polyurethane 6041 is gradually injected into the slurry and properly stirred and mixed to ensure it is evenly dispersed throughout the solution.

[0008] Preferably, the isophorone is synthesized by the mesityl oxide method or the acetone polycondensation method and has a high boiling point, low hygroscopicity, and good solubility, dispersibility, and leveling properties. The desired amount of conductive graphene is added to an appropriate amount of organic solvent and thoroughly stirred using a dispersing machine; this is used to improve the conductivity of the slurry and reduce its sintering temperature.

[0009] Preferably, the polymer dispersant is composed of polyacrylamide, which has properties such as good solubility and high stability. The polymer dispersant is primarily used to maintain the dispersion of graphene and silver particles in the slurry, ensuring uniformity and stability during preparation and use. Depending on specific requirements and process conditions, parameters such as the amount of polymer dispersant added, stirring time, temperature, and pressure need to be appropriately controlled to ensure the dispersant achieves optimal dispersion.

[0010] Preferably, the potassium ferrocyanide is a colorless crystal, easily soluble in water, stable in air, and has water-repellent properties, is anti-oxidant, anti-graphene, and anti-agglomeration of silver particles, and has better dispersion and arrangement properties.

[0011] Preferably, the dibasic acid dimethyl ester is composed of a mixture of three dibasic acid esters, and has the characteristics of low volatility, easy flow, high safety, and high photochemical stability.

[0012] A method for preparing a graphene-based conductive silver paste comprises the following steps: (11) fully mixing graphene with potassium ferrous oxide in a clean container; (12) adding a formulated resin and a solvent to the mixed powder, and mixing by stirring with a disperser; (13) repeatedly grinding the mixed powder several times using a three-roll grinder; and (14) adding silver particles and repeatedly grinding the mixed powder several times using a three-roll grinder to obtain a graphene conductive silver paste.

[0013] Preferably, the formulated resin is prepared by the following method: (21) first injecting 60-70% isophorone and 2-7% dimethyl dibasic acid into a container and stirring the solvent using a dispersing machine; (22) adjusting the stirring speed to 600-1000 rpm and gradually adding 18-25% chloroacetic acid resin and 5-15% polyurethane 6041 in small amounts; (23) increasing the speed of the dispersing machine until the chloroacetic acid resin and polyurethane 6041 are completely dispersed and dissolved; (24) the completely dissolved resin needs to be left to stand for more than 12 hours to expel bubbles; (25) injecting into a container, sealing and storing for later use.

[0014] Preferably, in step (13), the grinding fineness is 0.8-1.2 mm.

[0015] Preferably, in step (14), the grinding fineness is 0.2-0.4 mm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The graphene-based conductive silver paste of the present invention is made by grinding and processing graphene, silver particles, a polymer dispersant, potassium ferrocyanide, a formulated resin, dimethyl dibasic acid ester and other materials multiple times. The paste can release the solvent even in a low-temperature drying environment (70°C-120°C), and the binder (resin) is dried and solidified, thereby having good conductive properties. This allows the graphene-based conductive silver paste to better adhere to different types of substrates, has good adhesion and antioxidant properties, can maintain stable conductive properties during production and long-term use, and can extend the service life of the product. DETAILED DESCRIPTION

[0017] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] Example 1 A graphene-based conductive silver paste is composed of the following raw materials by weight: 40% graphene, 20% silver particles, 1.5% polymer dispersant, 2% potassium ferrocyanide, 25% formulation resin and 11.5% dimethyl dibasic acid.

[0019] Preferably, the formulated resin is composed of the following raw materials by weight: 18% chloroacetic acid resin, 15% polyurethane 6041, 60% isophorone and 7% dimethyl dibasic acid.

[0020] The above-mentioned graphene-based conductive silver paste is prepared according to the following steps: (11) In a clean container, graphene is fully mixed with potassium ferrous oxide; the polymer dispersant is slowly added during the grinding process; (12) The prepared resin and solvent are added to the mixed powder and mixed by manual stirring; (13) The mixture is repeatedly ground 8 times using a three-roll grinder to a grinding fineness of 1 mm; (14.) Silver particles are added and the mixture is repeatedly ground several times using a three-roll grinder to a grinding fineness of 0.3 mm to obtain graphene conductive silver paste. The prepared paste should be sealed and stored in an environment of 13°C ± 1°C. The prepared resin is prepared by the following method: (21) first inject isophorone and dimethyl dibasic acid into the container using a dispersing machine; (22) adjust the speed to 600 rpm-1000 rpm and stir and gradually add chloroacetic acid resin and polyurethane 6041 in small amounts; (23) increase the speed of the dispersing machine until the chloroacetic acid resin and polyurethane 6041 are completely dispersed and dissolved; (24) the completely dissolved resin needs to be left to stand for more than 12 hours to exhaust; (25) inject into the container, seal and store for later use.

[0021] Example 2 A graphene-based conductive silver paste is composed of the following raw materials by weight: 50% graphene, 10% silver particles, 0.5% polymer dispersant, 3% potassium ferrocyanide, 25% mixing resin and 11.5% dimethyl dibasic acid.

[0022] Preferably, the formulated resin is composed of the following raw materials by weight: 25% chloroacetic acid resin, 15% polyurethane 604, 68% isophorone and 2% dimethyl dibasic acid.

[0023] The preparation method of the graphene-based conductive silver paste is the same as that of Example 1 and will not be described in detail here.

[0024] Example 3 A graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 1.5% potassium ferrocyanide, 25% formulation resin and 12.5% ​​dimethyl dibasic acid.

[0025] Preferably, the formulated resin is composed of the following raw materials by weight: 20% chloroacetic acid resin, 10% polyurethane 6041, 65% isophorone and 5% dimethyl dibasic acid.

[0026] The preparation method of the graphene-based conductive silver paste is the same as that of Example 1 and will not be described in detail here.

[0027] Example 4 A graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 2% potassium ferrocyanide, 25% formulation resin and 12% dimethyl dibasic acid.

[0028] Preferably, the formulated resin is composed of the following raw materials by weight: 20% chloroacetic acid resin, 10% polyurethane 6041, 65% isophorone and 5% dimethyl dibasic acid.

[0029] The preparation method of the graphene-based conductive silver paste is the same as that of Example 1 and will not be described in detail here.

[0030] Example 5 A graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 2.5% potassium ferrocyanide, 25% formulation resin and 11.5% dimethyl dibasic acid.

[0031] Preferably, the formulated resin is composed of the following raw materials by weight: 20% chloroacetic acid resin, 10% polyurethane 6041, 65% isophorone and 5% dimethyl dibasic acid.

[0032] The preparation method of the graphene-based conductive silver paste is the same as that of Example 1 and will not be described in detail here.

[0033] Example 6 A graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 3% potassium ferrocyanide, 25% formulation resin and 11% dimethyl dibasic acid.

[0034] Preferably, the formulated resin is composed of the following raw materials by weight: 20% chloroacetic acid resin, 10% polyurethane 6041, 65% isophorone and 5% dimethyl dibasic acid.

[0035] The preparation method of the graphene-based conductive silver paste is the same as that of Example 1 and will not be described in detail here.

[0036] Comparative Example 1 Based on Example 3, the only difference from Example 3 is that potassium ferrocyanide is not added. Specifically, a graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 25% formulation resin, and 14% dimethyl dibasic acid.

[0037] Comparative Example 2 Based on Example 3, the only difference from Example 3 is the addition of 0.5% potassium ferrocyanide. Specifically, a graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 0.5% potassium ferrocyanide, 25% formulation resin, and 13.5% dimethyl dibasic acid.

[0038] Comparative Example 3 Based on Example 3, the only difference from Example 3 is the addition of 1% potassium ferrocyanide. Specifically, a graphene-based conductive silver paste is composed of the following raw materials by weight: 45% graphene, 15% silver particles, 1% polymer dispersant, 1% potassium ferrocyanide, 25% formulation resin, and 13% dimethyl dibasic acid.

[0039] The potassium ferrocyanide is a colorless crystal that is easily soluble in water and stable in air. It has good water-dissipation, anti-oxidation, and anti-agglomeration properties for graphene silver particles, and has better dispersibility and alignment. Potassium ferrocyanide is added to a graphene-based conductive silver paste and thoroughly mixed; the mixed graphene-based conductive silver paste is coated or printed on a desired substrate. This results in stronger coordination, solubility, redox, and other properties. The importance of potassium ferrocyanide is verified by comparing Examples 3 to 6 and Comparative Examples 1 to 3, as shown in the following table.

[0040] The present invention is manufactured through multiple grinding processes using materials such as graphene, silver particles, 7196 polymer dispersant, potassium ferrocyanide, formulated resin, and dimethyl dibasic acid. This allows for excellent conductivity even at low temperatures. This allows the graphene-based conductive silver paste to adhere better to various substrates, exhibiting excellent adhesion and oxidation resistance. It also maintains stable conductivity during manufacturing and long-term use, extending the product's service life.

[0041] The above-mentioned embodiments merely express the implementation methods of the present invention. The description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. Any technical solution obtained in the form of equivalent replacement or equivalent transformation should fall within the scope of protection of the present invention.

Claims

1. A graphene-based conductive silver paste, characterized in that: The invention is composed of the following raw materials by weight: 40-50% of graphene, 10-20% of silver particles, 0.5-1.5% of a polymer dispersant, 1-2% of potassium ferrocyanide, 25-35% of a mixing resin and 10-15% of dimethyl dibasic acid.

2. The graphene-based conductive silver paste according to claim 1, characterized in that The formulated resin is composed of the following raw materials by weight: 18-25% of chloroacetic acid resin, 5-15% of polyurethane 6041, 60-70% of isophorone and 2-7% of dimethyl dibasic acid.

3. A method for preparing a graphene-based conductive silver paste according to claim 1, characterized in that: It includes the following steps: (11) In a clean container, graphene is fully mixed with potassium ferrous oxide; (12) The prepared resin and solvent are added to the mixed powder and mixed by stirring with a disperser; (13) The mixture is repeatedly ground several times using a three-roll mill; (14) Silver particles are added and the mixture is repeatedly ground several times using a three-roll mill to obtain a graphene conductive silver slurry.

4. The method for preparing a graphene-based conductive silver paste according to claim 3, wherein: The formulated resin is prepared by the following method: (21) first injecting 60-70% isophorone and 2-7% dimethyl dibasic acid into a container and stirring the solvent using a dispersing machine; (22) adjusting the stirring speed to 600-1000 rpm and gradually adding 18-25% chloroacetic acid resin and 5-15% polyurethane 6041 in small amounts; (23) increasing the speed of the dispersing machine until the chloroacetic acid resin and polyurethane 6041 are completely dispersed and dissolved; (24) the completely dissolved resin needs to be left to stand for more than 12 hours to expel bubbles; (25) injecting into a container, sealing and storing for later use.

5. The method for preparing a graphene-based conductive silver paste according to claim 3, wherein: In step (13), the grinding fineness is 0.8~1.2mm.

6. The method for preparing a graphene-based conductive silver paste according to claim 3, wherein: In step (14), the grinding fineness is 0.2-0.4 mm.

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