Preparation method of a nano silver conductive composite material

Abstract

The present invention relates to the technical field of conductive composite materials, and discloses a preparation method of a nano-silver conductive composite material. The nano-silver conductive composite material of the present invention comprises 8-30 parts by weight of styrene-based 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, etc. The styrene-based polyvinyl alcohol contains carboxyl groups, which can form an interaction with the surface of the nano-silver, enabling the polyvinyl alcohol to play a better dispersion role, and the nano-silver to be more uniformly dispersed in the epoxy acrylate resin matrix, improving the electrical conductivity. The alkenyl groups contained in the styrene-based polyvinyl alcohol can undergo a photocuring crosslinking reaction with the epoxy acrylate resin, introducing the rigid and structurally stable benzene ring into the molecular chain of the epoxy acrylate resin, improving the cohesion and dimensional stability of the resin blend, and increasing the tensile shear strength and mechanical properties.

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 environmental friendliness 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 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:

[0006] (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. After stirring and reacting, add acetone to dilute the solution, filter, wash with acetone, and dry to obtain styryl polyvinyl alcohol.

[0007] The reaction formula is:

[0008]

[0009] (2) Add 8 - 30 parts by weight of styryl polyvinyl alcohol to water, heat and stir, cool, then add 140 - 300 parts by weight of nano silver, perform ultrasonic oscillation and then stir and disperse, dry to remove water, then add 30 - 45 parts by weight of active diluent, 100 parts by weight of epoxy acrylate resin, and 1 - 2.5 parts by weight of defoaming agent. After stirring, add 3.6 - 4.2 parts by weight of photoinitiator to obtain a nano silver conductive composite material.

[0010] Preferably, the temperature during the stirring reaction in (1) is 60 - 75 °C, and the reaction time is 3 - 6 h.

[0011] Preferably, the time of ultrasonic oscillation in (2) is 10 - 20 min.

[0012] Preferably, the temperature during stirring and dispersion is 25 - 40 °C, and the time is 2 - 4 h.

[0013] Preferably, the active diluent is dipropylene glycol diacrylate, dipropylene glycol diacrylate or 1,6 - hexanediol diacrylate.

[0014] Preferably, the photoinitiator is photoinitiator TPO or photoinitiator 184.

[0015] Preferably, the preparation method of 4 - (4 - vinylbenzoyl) 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 - vinylbenzoyl) phthalic anhydride. The reaction formula is:

[0016]

[0017] Preferably, the reaction solvent is tetrahydrofuran or dichloromethane.

[0018] (III) Beneficial technical effects of the present invention: React polyvinyl alcohol with 4 - (4 - vinylbenzoyl) 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 properties. When added to epoxy acrylate resin, it is beneficial to improve the adhesion between the resin and the substrate.

[0019] The styryl polyvinyl alcohol of the present invention contains carboxyl groups, which can form an interaction with the surface of nano - silver, enabling polyvinyl alcohol to play a better dispersing role, improving the dispersion effect of nano - silver, making nano - silver more uniformly dispersed in the epoxy acrylate resin matrix, forming a continuous conductive path, thereby reducing the volume resistivity and improving the electrical conductivity.

[0020] The styrenated polyvinyl alcohol of the present invention contains alkenyl groups and multiple rigid benzene ring structures. The alkenyl groups can undergo photocuring crosslinking reactions with epoxy acrylate resins, thereby improving the interfacial bonding performance between polyvinyl alcohol and epoxy acrylate resins. At the same time, benzene rings with rigidity and structural stability are introduced into the molecular chains of epoxy acrylate resins, enhancing the cohesive force and dimensional stability of the resin blend, and increasing 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, and other fields. Detailed Embodiments

[0021] 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.

[0022] 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.

[0023] Example 1:

[0024] (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.

[0025] (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 styrenated polyvinyl alcohol.

[0026] (3) Add 0.8 g of styrenated 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 the nano-silver conductive composite material.

[0027] Example 2:

[0028] (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 the reaction at 25 °C for 18 h. After filtration, rotary evaporate the filtrate and separate by column chromatography, eluting with a mixed solution of petroleum ether and ethyl acetate to obtain 4-(4-vinylbenzoate)phthalic anhydride.

[0029] (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 the reaction for 3 h, dilute with 40 mL of acetone, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0030] (3) Add 1.5 g of styryl polyvinyl alcohol to 200 mL of water. Heat to 95 °C and 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, 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 material.

[0031] Example 3:

[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 70 °C, add 0.2 g of 4-(4-vinylbenzoate)phthalic anhydride (prepared according to the method of Example 1), stir the reaction for 3 h, dilute with 40 mL of acetone, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0033] (2) Add 2.2 g of styryl polyvinyl alcohol to 300 mL of water. Heat to 95 °C and 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, 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 material.

[0034] Example 4:

[0035] (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 the reaction for 6 h, dilute with 50 mL of acetone, wash with acetone after filtration, and dry to obtain styryl polyvinyl alcohol.

[0036] (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, 0.25 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0037] Comparative Example 1

[0038] (1) Add 14 g of silver nanoparticles to 3.9 g of dipropylene glycol diacrylate, then add 10 g of epoxy acrylate resin, 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0039] Comparative Example 2

[0040] (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, 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0041] Comparative Example 3

[0042] (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, add 50 mL of acetone for dilution, filter and wash with acetone, and dry to obtain maleate-based polyvinyl alcohol.

[0043] (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, 0.2 g of defoamer BYK-A530. After stirring, add 0.42 g of photoinitiator TPO to obtain a silver nanoparticle conductive composite material.

[0044] The nano-silver conductive composite material was sprayed on the surface of tinplate, irradiated and cured in a UV curing machine with a power of 2 kW for 60 s, and left for 24 h. The adhesion grade of the paint film was tested according to the standard of GB / T 1720-2020. The volume resistivity ρ of the paint film was tested by a double-electrode four-probe tester.

[0045] 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 slide, and then two clean steel sheets were overlapped on the surface of the glass slide, irradiated and cured in a UV curing machine with a power of 2 kW for 60 s, and left for 24 h, and the tensile shear strength was tested.

[0046] Table 1 Performance test of nano-silver conductive composite material

[0047]

[0048] As can be seen from Table 1, the adhesion grade of the nano-silver conductive composite material in Comparative Example 1 was only level 2, and the tensile shear strength was low, the volume resistivity was large, and the bonding performance, mechanical strength and electrical conductivity were 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 dispersion role, improving the dispersion effect of nano-silver, making nano-silver more uniformly 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 had good adhesion grades and tensile shear strengths, and low volume resistivity and excellent electrical conductivity.

[0049] Compared with Example 1, in Comparative Example 2, only polyvinyl alcohol was added. It does not contain carboxyl groups, has a weak interaction with the surface of silver nanoparticles, and has poor dispersion performance, failing to improve the dispersion effect of silver nanoparticles well, resulting in a relatively large volume resistivity of the composite material. Moreover, polyvinyl alcohol does not contain benzene rings or alkenyl groups and cannot undergo a photocuring reaction with epoxy acrylate resin, leading to a low shear strength of the composite material. In Comparative Example 3, maleic anhydride was reacted with polyvinyl alcohol to obtain maleate group-containing polyvinyl alcohol, which contains carboxyl groups and can form an interaction with the surface of silver nanoparticles, enabling polyvinyl alcohol to play a better dispersion role. The silver nanoparticles are more uniformly dispersed in the epoxy acrylate resin matrix, forming a continuous conductive path, reducing the volume resistivity, and improving the electrical conductivity. Although the maleate group-containing polyvinyl alcohol contains alkenyl groups and can undergo a photocuring reaction with epoxy acrylate resin, it does not contain a benzene ring structure, resulting in a tensile shear strength lower than that of Example 1.

[0050] 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 of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a nano-silver conductive composite material, characterized in that, The preparation method is as follows: (1) Add polyvinyl alcohol to dimethyl sulfoxide, heat and stir, then add 4-(4-vinylbenzoyl) phthalic anhydride. After stirring and reacting, add acetone to dilute the solution, filter, wash, and dry to obtain styryl polyvinyl alcohol; (2) Add 8 - 30 parts by weight of styryl polyvinyl alcohol to water, heat and stir. After cooling, add 140 - 300 parts by weight of silver nanoparticles, 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, and 1 - 2.5 parts by weight of defoaming agent. After stirring, add 3.6 - 4.2 parts by weight of photoinitiator to obtain a silver nanoparticle conductive composite; In the above (1), the dosage of polyvinyl alcohol is 100 parts by weight, and the dosage of 4-(4-vinylbenzoyl) phthalic anhydride is 10 - 40 parts by weight.

2. The preparation method of the nano silver conductive composite material according to claim 1, characterized in that, In the above (1), the temperature during the stirring reaction is 60 - 75 °C, and the reaction time is 3 - 6 h.

3. The preparation method of the nano-silver conductive composite material according to claim 1, wherein In (2), the time of ultrasonic oscillation is 10 - 20 min; the temperature during the stirring dispersion is 25 - 40 °C, and the time is 2 - 4 h.

4. The preparation method of the nano silver conductive composite material according to claim 1, characterized in that, The reactive diluent is dipropylene glycol triacrylate, dipropylene glycol diacrylate, or 1,6-hexanediol diacrylate.

5. The preparation method of the silver nanowire conductive composite material according to claim 1, characterized in that, The photoinitiator is photoinitiator TPO or photoinitiator 184.

6. The preparation method of the nano silver conductive composite material according to claim 1, characterized in that, The preparation method of 4-(4-vinylbenzoyl) 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 and separate by column chromatography to obtain 4-(4-vinylbenzoyl) phthalic anhydride.

7. The preparation method of the silver nanowire conductive composite material according to claim 6, wherein, The reaction solvent is tetrahydrofuran or dichloromethane.

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