Preparation method of nano-silver conductive composite material

Abstract

The invention relates to the technical field of conductive composite materials, and discloses a preparation method of a nano-silver conductive composite material, and the nano-silver conductive composite material comprises 8-30 parts by weight of styryl polyvinyl alcohol, 140-300 parts by weight of nano-silver, 30-45 parts by weight of an active diluent, 100 parts by weight of epoxy acrylate resin and the like. The styryl polyvinyl alcohol contains carboxyl groups and can interact with the surface of the nano-silver, so that the polyvinyl alcohol has a better dispersion effect, the nano-silver is more uniformly dispersed in an epoxy acrylate resin matrix, and the conductivity is improved. Alkenyl contained in the styryl polyvinyl alcohol can be subjected to a photocuring cross-linking reaction with the epoxy acrylate resin, and a benzene ring with rigidity and structural stability is introduced into a molecular chain of the epoxy acrylate resin, so that the cohesion and the dimensional stability of a resin blend are improved, and the tensile shear strength and the mechanical property are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive composite materials, and particularly to a preparation method of a nano-silver conductive composite material. Background Art

[0002] Nano-silver has excellent electrical conductivity. By compounding nano-silver with epoxy resin, acrylic resin, polyurethane, etc., products such as conductive ink, conductive adhesive, and antibacterial plastic can be made. Due to its small particle size and large specific surface area, nano-silver is prone to agglomeration, which will affect the performance of the composite material. Therefore, dispersants such as polyvinyl alcohol, polyethylene glycol, and oleic acid need to be added during use.

[0003] Epoxy acrylate resin is a kind of excellent photocurable resin with the advantages of green environmental protection and fast curing speed, and has important applications in inks, adhesives, etc. Chinese patent application document CN119614021A discloses a preparation method of a waterborne UV-curable conductive ink. By compounding a modified waterborne UV resin, nano-silver, a nano-silver-graphene composite material, etc., the obtained UV-curable conductive ink has good electrical conductivity and other properties. However, this patent uses expensive graphene and does not improve the tensile shear strength of the UV resin, which is not conducive to the practical application of the UV resin in conductive adhesives. Summary of the Invention

[0004] (1) The technical problem solved by the present invention is: solving the problem of relatively low strength and adhesion of the nano-silver epoxy resin material.

[0005] (2) The technical solution of the present invention: A preparation method of a nano-silver conductive composite material: (1) Add 100 parts by weight of polyvinyl alcohol to dimethyl sulfoxide, heat and stir, then add 10 - 40 parts by weight of 4-(4-vinylbenzoate) phthalic anhydride, stir and react, add acetone to dilute the solution, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0006] The reaction formula is:

[0007] (2) Add 8 - 30 parts by weight of styryl polyvinyl alcohol to water, heat and stir, cool and then add 140 - 300 parts by weight of nano-silver, ultrasonically oscillate and then stir to disperse, dry to remove water, then add 30 - 45 parts by weight of reactive diluent, 100 parts by weight of epoxy acrylate resin, 1 - 2.5 parts by weight of defoamer, stir and then add 3.6 - 4.2 parts by weight of photoinitiator to obtain the nano-silver conductive composite material.

[0008] Preferably, the temperature during the stirring reaction in (1) is 60 - 75°C, and the reaction time is 3 - 6 h.

[0009] Preferably, the time of ultrasonic oscillation in (2) is 10 - 20 min.

[0010] Preferably, the temperature during stirring and dispersion is 25 - 40 °C, and the time is 2 - 4 h.

[0011] Preferably, the active diluent is dipropylene glycol triacrylate, dipropylene glycol diacrylate or 1,6 - hexanediol diacrylate.

[0012] Preferably, the photoinitiator is photoinitiator TPO or photoinitiator 184.

[0013] Preferably, the preparation method of 4 - (4 - vinylbenzoate) phthalic anhydride is as follows: Add 100 parts by weight of 4 - hydroxyphthalic anhydride, 101 - 112 parts by weight of 4 - vinylbenzoyl chloride, and 76 - 84 parts by weight of pyridine to the reaction solvent. Stir and react at 20 - 25 °C for 18 - 24 h. After filtration, rotary evaporate the filtrate, separate by column chromatography, and elute with a mixed solution of petroleum ether and ethyl acetate to obtain 4 - (4 - vinylbenzoate) phthalic anhydride. The reaction formula is:

[0014] Preferably, the reaction solvent is tetrahydrofuran or dichloromethane.

[0015] (III) Beneficial technical effects of the present invention: React polyvinyl alcohol with 4 - (4 - vinylbenzoate) phthalic anhydride to obtain styryl polyvinyl alcohol, and then blend it with nano - silver, epoxy acrylate resin, active diluent, photoinitiator, etc. to obtain a nano - silver conductive composite material. Polyvinyl alcohol has good adhesion performance. When added to epoxy acrylate resin, it is beneficial to improve the adhesion between the resin and the substrate.

[0016] The styryl polyvinyl alcohol of the present invention contains carboxyl groups, which can form interactions with the surface of nano - silver, enabling polyvinyl alcohol to play a better dispersion role, improving the dispersion effect of nano - silver, making nano - silver more evenly dispersed in the epoxy acrylate resin matrix, forming a continuous conductive path, thereby reducing the volume resistivity and improving the conductivity.

[0017] The styryl polyvinyl alcohol of the present invention contains alkenyl groups and multiple rigid benzene ring structures. The alkenyl groups can undergo photo - curing cross - linking reactions with epoxy acrylate resin, thereby improving the interfacial bonding performance between polyvinyl alcohol and epoxy acrylate resin. At the same time, introducing rigid and structurally stable benzene rings into the molecular chain of epoxy acrylate resin improves the cohesion and dimensional stability of the resin blend, and increases the tensile shear strength and mechanical properties. The nano - silver conductive composite material prepared by the present invention has broad application prospects in conductive adhesives, conductive inks, etc. Detailed implementation manners

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] The following epoxy acrylate resin, model 1030, is purchased from Shandong Huling New Materials Co., Ltd. The nano silver, model CB2311, with a particle size between 20 - 80 nm, is purchased from Wuhan Lvjing Fenghua Biotechnology Co., Ltd.

[0020] Example 1:

[0021] (1) Add 2 g of 4-hydroxyphthalic anhydride, 2.02 g of 4-vinylbenzoyl chloride, and 1.68 g of pyridine to 25 mL of tetrahydrofuran, stir and react at 20°C for 24 h. After filtration, rotary evaporate the filtrate, separate by column chromatography, and elute with a mixed solution of petroleum ether and ethyl acetate to obtain 4-(4-vinylbenzoate) phthalic anhydride.

[0022] (2) Add 2 g of polyvinyl alcohol to 30 mL of dimethyl sulfoxide, heat to 90°C and stir for 20 min, cool to 60°C, add 0.6 g of 4-(4-vinylbenzoate) phthalic anhydride, stir and react for 4 h, dilute with 50 mL of acetone, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0023] (3) Add 0.8 g of styryl polyvinyl alcohol to 150 mL of water, heat to 90°C, stir for 20 min, cool to room temperature, add 14 g of nano silver, ultrasonically oscillate for 10 min, then stir and disperse at 30°C for 2 h, dry to remove water, then add 3.9 g of dipropylene glycol diacrylate, 10 g of epoxy acrylate resin, and 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a nano silver conductive composite material.

[0024] Example 2:

[0025] (1) Add 2 g of 4-hydroxyphthalic anhydride, 2.24 g of 4-vinylbenzoyl chloride, and 1.52 g of pyridine to 30 mL of dichloromethane, stir and react at 25°C for 18 h. After filtration, rotary evaporate the filtrate, separate by column chromatography, and elute with a mixed solution of petroleum ether and ethyl acetate to obtain 4-(4-vinylbenzoate) phthalic anhydride.

[0026] (2) Add 2 g of polyvinyl alcohol to 30 mL of dimethyl sulfoxide, heat to 90 °C and stir for 20 min, cool to 75 °C, add 0.8 g of 4-(4-vinylbenzoate) phthalic anhydride, stir and react for 3 h, add 40 mL of acetone for dilution, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0027] (3) Add 1.5 g of styryl polyvinyl alcohol to 200 mL of water, heat to 95 °C, stir for 20 min, cool to room temperature, add 20 g of silver nanoparticles, ultrasonically oscillate for 10 min, then stir and disperse at 25 °C for 4 h, dry to remove water, and then add 4.5 g of 1,6-hexanediol diacrylate, 10 g of epoxy acrylate resin, and 0.1 g of defoamer BYK-A530. After stirring, add 0.36 g of photoinitiator 184 to obtain a silver nanoparticle conductive composite.

[0028] Example 3:

[0029] (1) Add 2 g of polyvinyl alcohol to 20 mL of dimethyl sulfoxide, heat to 95 °C and stir for 10 min, cool to 70 °C, add 0.2 g of 4-(4-vinylbenzoate) phthalic anhydride (prepared according to the method of Example 1), stir and react for 3 h, add 40 mL of acetone for dilution, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0030] (2) Add 2.2 g of styryl polyvinyl alcohol to 300 mL of water, heat to 95 °C, stir for 20 min, cool to room temperature, add 25 g of silver nanoparticles, ultrasonically oscillate for 20 min, then stir and disperse at 40 °C for 2 h, dry to remove water, and then add 3 g of dipropylene glycol diacrylate, 10 g of epoxy acrylate resin, and 0.25 g of defoamer BYK-A530. After stirring, add 0.38 g of photoinitiator 184 to obtain a silver nanoparticle conductive composite.

[0031] Example 4:

[0032] (1) Add 2 g of polyvinyl alcohol to 20 mL of dimethyl sulfoxide, heat to 95 °C and stir for 10 min, cool to 60 °C, add 0.4 g of 4-(4-vinylbenzoate) phthalic anhydride (prepared according to the method of Example 1), stir and react for 6 h, add 50 mL of acetone for dilution, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0033] (2) Add 3 g of styryl polyvinyl alcohol to 300 mL of water, heat to 95 °C, stir for 10 min, cool to room temperature, add 30 g of silver nanoparticles, ultrasonically oscillate for 10 min, then stir and disperse at 40 °C for 3 h, dry to remove water, and then add 4.2 g of dipropylene glycol diacrylate, 10 g of epoxy acrylate resin, and 0.25 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0034] Comparative Example 1 (1) Add 14 g of silver nanoparticles to 3.9 g of dipropylene glycol diacrylate, then add 10 g of epoxy acrylate resin and 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0035] Comparative Example 2 (1) Add 0.8 g of polyvinyl alcohol to 150 mL of water, heat to 90 °C, stir for 20 min, cool to room temperature, add 14 g of silver nanoparticles, ultrasonically oscillate for 10 min, then stir and disperse at 30 °C for 2 h, dry to remove water, and then add 3.9 g of dipropylene glycol diacrylate, 10 g of epoxy acrylate resin, and 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0036] Comparative Example 3 (1) Add 2 g of polyvinyl alcohol to 30 mL of dimethyl sulfoxide, heat to 90 °C and stir for 20 min, cool to 60 °C, add 0.6 g of maleic anhydride, stir and react for 4 h, dilute with 50 mL of acetone, filter and wash with acetone, and dry to obtain maleate-based polyvinyl alcohol.

[0037] (2) Add 0.8 g of maleate-based polyvinyl alcohol to 150 mL of water, heat to 90 °C, stir for 20 min, cool to room temperature, add 14 g of silver nanoparticles, ultrasonically oscillate for 10 min, then stir and disperse at 30 °C for 2 h, dry to remove water, and then add 3.9 g of dipropylene glycol diacrylate, 10 g of epoxy acrylate resin, and 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0038] Spray the silver nanoparticle conductive composite material on the surface of tinplate, irradiate and cure in a UV curing machine with a power of 2 kW for 60 s, and let it stand for 24 h. Test the adhesion grade of the paint film according to the GB / T 1720-2020 standard. Use a double-electrode four-probe tester to test the volume resistivity ρ of the paint film.

[0039] The shear strength was tested according to the standard of GB / T 7124-2008. The nano-silver conductive composite material was coated on the surface of a clean glass sheet, and then two clean steel sheets were overlapped on the surface of the glass sheet. It was irradiated and cured in a UV curing machine with a power of 2 kW for 60 s, and then left for 24 h, and the tensile shear strength was tested.

[0040] Table 1 Performance Test of Nano-Silver Conductive Composite Material

[0041] As can be seen from Table 1, the adhesion grade of the nano-silver conductive composite material in Comparative Example 1 is only level 2, and the tensile shear strength is low, the volume resistivity is large, and the bonding performance, mechanical strength and electrical conductivity are not good. Styrene-based polyvinyl alcohol was added to the nano-silver conductive composite material in Example 1. Polyvinyl alcohol itself has good bonding performance, which is beneficial to improving the adhesion between the epoxy acrylate resin composite material and the substrate. At the same time, styrene-based polyvinyl alcohol contains carboxyl groups, which can form an interaction with the surface of nano-silver, making polyvinyl alcohol play a better dispersing role, improving the dispersion effect of nano-silver, making nano-silver more evenly dispersed in the epoxy acrylate resin matrix, forming a continuous conductive path, thereby reducing the volume resistivity and improving the electrical conductivity. And styrene-based polyvinyl alcohol contains alkenyl groups and multiple rigid benzene ring structures. The alkenyl groups can undergo a photocuring crosslinking reaction with the epoxy acrylate resin, thereby improving the interfacial bonding performance between polyvinyl alcohol and the epoxy acrylate resin. At the same time, the rigid and structurally stable benzene rings are introduced into the molecular chain of the epoxy acrylate resin, improving the cohesion and dimensional stability of the resin blend, which is beneficial to increasing the tensile shear strength and mechanical properties. Different amounts of nano-silver and styrene-based polyvinyl alcohol were added in Examples 2-4, and the composite materials also have good adhesion grades and tensile shear strengths, and low volume resistivity and excellent electrical conductivity.

[0042] Compared with Example 1, only polyvinyl alcohol was added in Comparative Example 2. It does not contain carboxyl groups, has a weak interaction with the surface of nano-silver, and has a poor dispersing effect, and does not well improve the dispersion effect of nano-silver, resulting in a large volume resistivity of the composite material. And polyvinyl alcohol does not contain benzene rings or alkenyl groups, and cannot undergo a photocuring reaction with the epoxy acrylate resin, resulting in a low shear strength of the composite material. In Comparative Example 3, maleic anhydride was reacted with polyvinyl alcohol to obtain maleate-based polyvinyl alcohol, which contains carboxyl groups and can form an interaction with the surface of nano-silver, making polyvinyl alcohol play a better dispersing role, and nano-silver is more evenly dispersed in the epoxy acrylate resin matrix, forming a continuous conductive path, reducing the volume resistivity and improving the electrical conductivity. Although maleate-based polyvinyl alcohol contains alkenyl groups and can undergo a photocuring reaction with the epoxy acrylate resin, it does not contain benzene ring structures, resulting in a lower tensile shear strength than that of Example 1.

[0043] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a nano silver conductive composite material, characterized in that: The preparation method is: (1) Add polyvinyl alcohol to dimethyl sulfoxide, add 4-(4-vinylbenzoate)phthalic anhydride after heating and stirring, stir and react, add acetone to dilute the solution, filter, wash, and dry to obtain styrene-based polyvinyl alcohol; (2) Add 8-30 parts by weight of styrene-based polyvinyl alcohol to water, heat and stir, add 140-300 parts by weight of nanosilver after cooling, stir and disperse after ultrasonic vibration, dry to remove water, then add 30-45 parts by weight of active diluent, 100 parts by weight of epoxy acrylate resin, 1-2.5 parts by weight of defoamer, stir and add 3.6-4.2 parts by weight of photoinitiator to obtain a nanosilver conductive composite material.

2. The method for preparing the nano silver conductive composite material according to claim 1, characterized in that: In the above (1), the amount of polyvinyl alcohol used is 100 parts by weight, and the amount of 4-(4-vinylbenzoate)phthalic anhydride is 10-40 parts by weight.

3. The method for preparing the nano silver conductive composite material according to claim 1, characterized in that: The stirring reaction temperature in (1) is 60-75°C, and the reaction time is 3-6h.

4. The method for preparing the nano silver conductive composite material according to claim 1, characterized in that: (2) The ultrasonic oscillation time is 10-20 minutes; the temperature during stirring and dispersion is 25-40°C and the time is 2-4 hours.

5. The method for preparing the nano-silver conductive composite material according to claim 1, characterized in that: The active diluent is tripropylene glycol diacrylate, dipropylene glycol diacrylate or 1,6-hexanediol diacrylate.

6. The method for preparing the nano-silver conductive composite material according to claim 1, characterized in that: The photoinitiator is photoinitiator TPO or photoinitiator 184.

7. The method for preparing the nano-silver conductive composite material according to claim 1, characterized in that: The preparation method of the 4-(4-vinylbenzoate)-phthalic anhydride is as follows: 100 parts by weight of 4-hydroxyphthalic anhydride, 101-112 parts by weight of 4-vinylbenzoyl chloride, and 76-84 parts by weight of pyridine are added to a reaction solvent, and the mixture is stirred at 20-25° C. for 18-24 hours, and the filtrate is rotary evaporated after filtering, and separated by column chromatography to obtain 4-(4-vinylbenzoate)-phthalic anhydride.

8. The method for preparing the nano-silver conductive composite material according to claim 7, characterized in that: The reaction solvent is tetrahydrofuran or dichloromethane.

Images