A high-strength and high-elongation conductive glue and its preparation method

Abstract

The present invention relates to the technical field of adhesives, and specifically discloses a high-strength and high-elongation conductive adhesive and a preparation method thereof; the conductive adhesive comprises an aqueous polyacrylic acid adhesive and a conductive agent; the aqueous polyacrylic acid adhesive comprises the following raw materials: by weight, 8-10 parts of polyacrylic acid, 2-3 parts of a high molecular polymer, 1-2 parts of a crosslinking agent, and 4-7 parts of pure water; the Rockwell hardness of the high molecular polymer is 100-200, the Tg is below 90 °C, and the D90 is 5-10 μm; compared with the traditional formula, the formula of the present invention is safer. The present invention directly uses pure water as a solvent, is simple to prepare, pollution-free, harmless to operators, and does not require an additional NMP recovery device and ventilation system, greatly saving equipment costs; by using the present invention, an adhesive with enhanced tensile strength and elongation can be obtained, and the preparation method of the adhesive of the present invention is simple and suitable for popularization and use.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and specifically discloses a high-strength and high-elongation conductive adhesive and a preparation method thereof. Background Art

[0002] Carbon-coated aluminum foil refers to an aluminum foil material with a carbon-containing coating on its surface, which is widely used in the new energy field and can be used to prepare the positive current collector of lithium-ion batteries.

[0003] The coating of carbon-coated aluminum foil requires excellent electrical conductivity, excellent mechanical strength, and light weight. The adhesive is an important component of the coating, which is used to ensure the dispersion of conductive particles during the coating process, as well as the adhesion and integrity of the coating. Therefore, the selection and formulation of the adhesive have an important impact on the performance of carbon-coated aluminum foil, and it needs to have properties including good electrical conductivity, mechanical strength, water resistance, etc. However, the water-based polyacrylic adhesive used in current carbon-coated aluminum foil products has insufficient mechanical strength and is prone to cracking and tape breakage during the next rolling process, affecting the coating performance. Therefore, it is of great significance to study a high-strength and high-elongation conductive adhesive and a preparation method thereof. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-strength and high-elongation conductive adhesive and a preparation method thereof to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A high-strength and high-elongation conductive adhesive: The conductive adhesive includes a water-based polyacrylic adhesive and a conductive agent; the water-based polyacrylic adhesive includes the following raw materials: by weight, 8 - 10 parts of polyacrylic acid, 2 - 3 parts of a high molecular polymer, 1 - 2 parts of a cross-linking agent, and 4 - 7 parts of pure water.

[0006] Preferably, the water-based polyacrylic adhesive includes the following raw materials: by weight, 10 parts of polyacrylic acid, 3 parts of a high molecular polymer, 2 parts of a cross-linking agent, and 4 parts of pure water.

[0007] Preferably, the high molecular polymer includes one or two of polymethyl methacrylate and polycarbonate.

[0008] Preferably, the average molecular weight of the polyacrylic acid is M.W ~ 5,000.

[0009] Preferably, the cross-linking agent includes a trifunctional aziridine cross-linking agent.

[0010] Preferably, the preparation method of the above high-strength and high-elongation conductive glue includes the following steps: (1) Take polyacrylic acid and a high molecular polymer, mix and stir at 25°C for 20-30 minutes to obtain a slurry; mix the cross-linking agent and pure water, add them to the slurry, and continue to disperse for 20-40 minutes to mix evenly to obtain an aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue and the conductive agent evenly to obtain the conductive glue.

[0011] Preferably, the addition amount of the conductive agent accounts for 50%-80% of the mass of the dry matter in the conductive glue.

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are: providing a glue with enhanced tensile strength and elongation. Using the glue of the present invention can improve the water resistance, tensile strength and elongation of the product itself while ensuring the original bonding strength, and reduce cracking, peeling, belt breakage and wrinkling;

[0013] Polyacrylic acid can form a stable solution in water. Among them, (-COOH) has strong acidity, making polyacrylic acid have good acid-base neutralization ability and metal ion complexation ability. When coated on metal aluminum foil and copper foil, it has excellent adhesiveness; the high molecular polymer selects microspheres with a D90 of 5-10 μm, which have a large specific surface area, strong adsorption, large aggregation effect and strong surface reaction ability. Although the particle size is very small, it still has good mechanical strength (Rockwell hardness is 100-200), and can be used to manufacture high-strength and lightweight products. When used in blend with polyacrylic acid, it can reinforce the overall system. At the same time, a high molecular polymer with a Tg below 90°C is selected. During the high-temperature curing process, it can undergo secondary dispersion adhesion, which can fix and support the overall carbon-coated layer and enhance the mechanical strength;

[0014] Compared with the traditional formula, the formula of the present invention is safer. The present invention directly uses pure water as a solvent, is simple to prepare, pollution-free, harmless to operators, and at the same time does not require an additional NMP recovery device and ventilation system, greatly saving equipment costs; by using the present invention, a glue with enhanced tensile strength and elongation can be obtained, and the preparation method of the glue of the present invention is simple and suitable for popularization and use. Detailed Embodiments

[0015] The following are the preferred embodiments of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. For those of ordinary skill in the art in this technical field, without departing from the principle of the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0016] Unless otherwise specified, the following parts are by mass;

[0017] Example 1: (1) Take polyacrylic acid and polymethyl methacrylate, mix and stir at 25°C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly, obtaining an aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0018] The aqueous polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 1 part of crosslinking agent, and 4 parts of pure water;

[0019] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0020] Example 2: (1) Take polyacrylic acid and polymethyl methacrylate, mix and stir at 25°C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly, obtaining an aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0021] The aqueous polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 3 parts of polymethyl methacrylate, 1 part of crosslinking agent, and 4 parts of pure water;

[0022] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0023] Example 3: (1) Take polyacrylic acid and polymethyl methacrylate, mix and stir at 25°C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly, obtaining an aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0024] The aqueous polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 2 parts of crosslinking agent, and 4 parts of pure water;

[0025] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0026] Example 4: (1) Take polyacrylic acid and polymethyl methacrylate, mix and stir at 25°C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly, obtaining an aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0027] The aqueous polyacrylic acid glue comprises the following raw materials: 10 parts of polyacrylic acid, 3 parts of polymethyl methacrylate, 2 parts of crosslinking agent, and 4 parts of pure water;

[0028] The addition amount of the conductive agent accounts for 60% of the mass of the dry materials in the conductive glue.

[0029] Comparative Example 1: Traditional glue: Take 2 parts of polyvinylidene fluoride and 7 parts of N-methylpyrrolidone, mix and stir for 120 min to obtain a glue precursor, then add 1 part of dispersant and 2 parts of conductive agent, and stir for 60 min to obtain the traditional glue.

[0030] Comparative Example 2: (Using a polyurethane with a Tg above 90 °C to replace polymethyl methacrylate, and the remaining method steps are the same as those in Example 1) (1) Take polyacrylic acid and polyurethane, mix and stir at 25 °C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly to obtain the aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue with the conductive agent evenly to obtain the conductive glue;

[0031] The aqueous polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 1 part of crosslinking agent, and 4 parts of pure water;

[0032] The addition amount of the conductive agent accounts for 60% of the mass of the dry materials in the conductive glue.

[0033] Comparative Example 3: (Using polyglycolic acid with a Rockwell hardness above 200 to replace polymethyl methacrylate, and the remaining method steps are the same as those in Example 1) (1) Take polyacrylic acid and polyglycolic acid, mix and stir at 25 °C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly to obtain the aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue with the conductive agent evenly to obtain the conductive glue;

[0034] The aqueous polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 1 part of crosslinking agent, and 4 parts of pure water;

[0035] The addition amount of the conductive agent accounts for 60% of the mass of the dry materials in the conductive glue.

[0036] Comparative Example 4: (Selecting polycarbonate with a particle size of 50 microns to replace polymethyl methacrylate, and the remaining method steps are the same as those in Example 1) (1) Take polyacrylic acid and polycarbonate, mix and stir at 25 °C for 25 min to obtain a slurry; mix the crosslinking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly to obtain the aqueous polyacrylic acid glue; (2) Mix the aqueous polyacrylic acid glue with the conductive agent evenly to obtain the conductive glue;

[0037] The water-based polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 1 part of cross-linking agent, and 4 parts of pure water;

[0038] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0039] Comparative Example 5: (Changing the addition amounts of polyacrylic acid, polymethyl methacrylate, and cross-linking agent, and the remaining method steps are the same as those in Example 1) (1) Take polyacrylic acid and polymethyl methacrylate, mix and stir at 25 °C for 25 min to obtain a slurry; mix the cross-linking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly to obtain a water-based polyacrylic acid glue; (2) Mix the water-based polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0040] The water-based polyacrylic acid glue comprises the following raw materials: 4 parts of polyacrylic acid, 4 parts of polymethyl methacrylate, 2 parts of cross-linking agent, and 4 parts of pure water;

[0041] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0042] Comparative Example 6: (Using polylactic acid with a Rockwell hardness below 100 to replace polymethyl methacrylate, and the remaining method steps are the same as those in Example 1) (1) Take polyacrylic acid and polylactic acid, mix and stir at 25 °C for 25 min to obtain a slurry; mix the cross-linking agent and pure water, add them to the slurry, and continue to disperse for 30 min to mix evenly to obtain a water-based polyacrylic acid glue; (2) Mix the water-based polyacrylic acid glue and the conductive agent evenly to obtain a conductive glue;

[0043] The water-based polyacrylic acid glue comprises the following raw materials: 8 parts of polyacrylic acid, 2 parts of polymethyl methacrylate, 1 part of cross-linking agent, and 4 parts of pure water;

[0044] The addition amount of the conductive agent accounts for 60% of the mass of the dry matter in the conductive glue.

[0045] In the above embodiments, unless otherwise specified, the test methods used are all conventional methods; unless otherwise specified, the raw materials used can be obtained from commercial sources, and the raw material sources are as follows: polyacrylic acid (average molecular weight M.W~5,000, purchased from the National Pharmaceutical Group, pH=3.5~4.5); cross-linking agent (trifunctional aziridine cross-linking agent, purchased from the National Pharmaceutical Group, density 1.110~1.120g / mL; viscosity 1950mPa･s(50℃)); conductive agent (National Pharmaceutical Group, carbon black, model CP (Shanghai Test), ≥99.85%), polymethyl methacrylate (National Pharmaceutical Group, Alfa-043982), polyvinylidene fluoride (model Solvay 5800, Merck Chemical), polylactic acid (Maclean Group, purity 80%, Rockwell hardness 30~60), polyurethane (thermal decomposition temperature ≥150℃, Rockwell hardness 100~200, Merck Chemical, purity 85%), polyglycolic acid (Rockwell hardness 350, National Pharmaceutical Group, purity 85%), polycarbonate (average particle size 50 microns, Merck Science, purity 50%), dispersant (Bayer, Germany, high-efficiency emulsion dispersant Lucramul DA345).

[0046] Experiment: Take the conductive adhesives prepared in the examples and comparative examples, coat the adhesives on the aluminum foil by gravure coating method, the coating speed is 30m / min, the oven temperature is set at 120℃, after drying, take the a4 sample for testing. Cut the a4 sample into 15*1cm, and test the elongation and tensile strength of the sample on a universal tensile machine; the through resistance is tested by a pole piece resistance tester; the specific data are shown in the following table;

[0047]

[0048] Conclusion: Compared with Comparative Example 1, the conductive adhesive prepared in the embodiment of the present invention has a higher elongation and a greater tensile strength, and also has a greater advantage in conductivity; in Comparative Example 2, a polyurethane with a Tg above 90℃ is used instead of polymethyl methacrylate, and the conductivity decreases. It can be seen that the selection of the raw material Tg is of great significance; in Comparative Example 3, polyglycolic acid with a Rockwell hardness above 200 is used instead of polymethyl methacrylate, and in Comparative Example 6, polylactic acid with a Rockwell hardness below 100 is used instead of polymethyl methacrylate, and the performance decreases. It can be seen that controlling the Rockwell hardness of the raw materials is also of great significance; in Comparative Example 4, polycarbonate with a particle size of 50 microns is used instead of polymethyl methacrylate, and the performance is not as good as that of the example; in Comparative Example 5, the addition amounts of polyacrylic acid, polymethyl methacrylate, and cross-linking agent are changed, and the performance decreases; in summary, the high-strength and high-elongation conductive adhesive prepared by the present invention has excellent mechanical properties and strong conductivity.

[0049] Finally, it should be noted that the above are only the preferred embodiments of the present invention, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application, within the spirit and principle of the present invention, should be covered by the protection scope of this application; without conflict, the implementation manners and features in the implementation manners of this application can be combined with each other. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A high-strength and high-elongation conductive glue, characterized in that: The conductive glue comprises an aqueous polyacrylic acid glue and a conductive agent; the aqueous polyacrylic acid glue comprises the following raw materials in parts by weight: 8 to 10 parts of polyacrylic acid, 2 to 3 parts of a high molecular polymer, 1 to 2 parts of a crosslinking agent, and 4 to 7 parts of pure water; The polymer is polymethyl methacrylate Alfa-043982; the average molecular weight M of the polyacrylic acid w is 5,000; the crosslinking agent is a trifunctional aziridine crosslinking agent; The addition amount of the conductive agent accounts for 50% to 80% of the total mass of the dry materials in the conductive glue.

2. The high-strength and high-elongation conductive glue according to claim 1, wherein: The aqueous polyacrylic acid glue comprises the following raw materials: in parts by weight, 10 parts of polyacrylic acid, 3 parts of a high molecular polymer, 2 parts of a crosslinking agent, and 4 parts of pure water.

3. The preparation method of a high-strength and high-elongation conductive glue according to any one of claims 1 to 2, characterized in that, It includes the steps of: (1) taking polyacrylic acid and a high molecular polymer, and mixing them to obtain a slurry; mixing the crosslinking agent and pure water, and adding them to the slurry to obtain an aqueous polyacrylic acid glue by mixing; (2) mixing the aqueous polyacrylic acid glue with the conductive agent to obtain a conductive glue.

4. The preparation method of a high-strength and high-elongation conductive glue according to claim 3, characterized in that, It includes the steps of: (1) taking polyacrylic acid and a high molecular polymer, mixing and stirring them at 25°C for 20 to 30 minutes to obtain a slurry; mixing the crosslinking agent and pure water, adding them to the slurry, and continuing to disperse for 20 to 40 minutes to mix evenly to obtain an aqueous polyacrylic acid glue; (2) mixing the aqueous polyacrylic acid glue with the conductive agent evenly to obtain a conductive glue.

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