Conductive carbon paste as well as preparation method and application thereof

Abstract

The invention provides conductive carbon paste as well as a preparation method and application thereof, and belongs to the technical field of conductive materials. The carbon black, the graphene and the carbon nanotubes are utilized to form a self-supported three-dimensional conductive network, so that the graphene / carbon nanotube composite material has excellent conductivity. In addition, both the graphene and the carbon nanotubes have excellent mechanical properties, flexibility and chemical stability, so that the mechanical stability of a conductive layer after the conductive carbon paste is cured can be improved. And the high-temperature-resistant binder can improve the stability of the conductive layer after the conductive carbon paste is cured. The flexibility reinforcing agent can improve the flexibility of the conductive carbon paste. The silane coupling agent can play a bridge role between the carbon material and the high-temperature-resistant binder, so that the interface affinity between the carbon nanomaterial and the high-temperature-resistant binder is enhanced; the silane coupling agent effectively inhibits agglomeration of the graphene and the carbon nanotubes in a chemical adsorption or physical coating mode. The result of the embodiment shows that the conductive layer formed by curing the conductive carbon paste provided by the invention has excellent conductive stability and mechanical stability.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive materials, and in particular to a conductive carbon paste and a preparation method and application thereof. Background Art

[0002] As a functional electronic material, conductive carbon paste is widely used in many fields such as printed electronic components, solar cell components, automotive electronic components, medical electronic devices and bioelectronic devices due to its conductivity, printability, flexibility and cost advantages. For example, it is used in the port connection of medical devices to realize the electrical signal transmission or sensing function of medical devices. At present, the conductive carbon paste used on the market is mainly carbon nanotube conductive paste or graphene conductive paste. However, although carbon nanotubes and graphene have excellent conductivity, they have strong van der Waals forces, and the carbon nanotubes or graphene in the conductive carbon paste are easy to re-aggregate and delaminate. The delamination of the conductive carbon paste makes it difficult to ensure the conductivity and mechanical stability of the conductive layer of the conductive carbon paste during use. Therefore, the existing conductive carbon paste has problems such as insufficient conductive stability and poor mechanical durability during use. In particular, it is prone to resistance increase, cracking or peeling under long-term use or complex environments (such as high temperature, high humidity or mechanical stress), which makes it difficult to meet the needs of high-precision medical devices. Therefore, how to obtain a conductive carbon paste for a conductive layer with good conductive stability and mechanical stability is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0003] The purpose of the present invention is to provide a conductive carbon paste and its preparation method and application. The conductive layer formed after the conductive carbon paste provided by the present invention is cured has excellent conductive stability and mechanical stability.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a conductive carbon paste, which comprises the following components by weight: 20-30% carbon black, 5-10% graphene, 5-10% carbon nanotubes, 20-40% high temperature resistant binder, 10-20% flexibility enhancer, 2-5% silane coupling agent and the balance solvent;

[0006] The flexibility enhancer includes polyurethane or silicone.

[0007] Preferably, the particle size of the carbon black is 15 to 30 nm.

[0008] Preferably, the thickness of the graphene sheet is 1 to 10 nm; the diameter of the graphene sheet is 1 to 10 μm.

[0009] Preferably, the diameter of the carbon nanotube is 5-100 nm; the aspect ratio of the carbon nanotube is 500-3000.

[0010] Preferably, the high temperature resistant adhesive comprises polyimide or epoxy-acrylate copolymer.

[0011] Preferably, the epoxy-acrylate copolymer is of the model Ebecryl 3700.

[0012] Preferably, the silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0013] Preferably, the conductive carbon paste further includes an antioxidant, and the antioxidant is an oil-soluble phenol antioxidant.

[0014] The present invention also provides a method for preparing the conductive carbon paste described in the above technical solution, comprising the following steps:

[0015] (1) mixing carbon black, graphene, carbon nanotubes and a solvent to obtain a carbon material dispersion;

[0016] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and then subjecting the mixture to high-speed shearing to obtain a mixed slurry; the high-speed shearing speed is 5000 to 8000 rpm, and the high-speed shearing time is 40 to 60 minutes;

[0017] (3) mixing the mixed slurry obtained in step (2) with a silane coupling agent to obtain a conductive carbon slurry.

[0018] The present invention also provides the use of the conductive carbon paste described in the above technical solution or the conductive carbon paste prepared by the preparation method described in the above technical solution in medical electronic devices and bioelectronic devices.

[0019] The present invention provides a conductive carbon paste, which comprises the following components by weight: 20-30% carbon black, 5-10% graphene, 5-10% carbon nanotubes, 20-40% high-temperature resistant binder, 10-20% flexibility enhancer, 2-5% silane coupling agent and balance solvent; the flexibility enhancer comprises polyurethane or silicone. The present invention utilizes carbon black, graphene, and carbon nanotubes as conductive materials for conductive carbon paste. Graphene is a two-dimensional sheet structure, and carbon nanotubes are cylindrical with a hollow interior. Graphene and carbon nanotubes have similar carbon compositions, and can form a self-supporting three-dimensional network structure with carbon nanotubes and graphene through self-assembly, preventing the agglomeration of graphene and carbon nanotubes. Carbon black can be filled in the self-supporting three-dimensional network structure formed by carbon nanotubes and graphene. In this self-supporting three-dimensional network structure, carbon nanotubes can act as "wires." Carbon black, graphene, and carbon nanotubes can form point-to-surface contact, thereby providing the conductive carbon paste with abundant conductive pathways and excellent electrical conductivity. Furthermore, both graphene and carbon nanotubes have excellent mechanical properties, flexibility, and chemical stability, which can enhance the mechanical stability of the conductive layer formed after the conductive carbon paste is cured. A high-temperature resistant binder can enable the conductive carbon paste to withstand the high temperatures of the equipment during use, thereby enhancing the mechanical stability of the conductive layer formed after the conductive carbon paste is cured. Flexibility enhancers include polyurethane or silicone, which have good compatibility with the carbon materials (such as graphene, carbon black and carbon nanotubes) in the conductive carbon paste, and can improve the flexibility of the conductive layer formed after the conductive carbon paste is cured. Silane coupling agents have organic groups and inorganic active groups, which can act as a bridge between the carbon material and the high-temperature resistant binder, and enhance the interfacial affinity between the carbon nanomaterial and the high-temperature resistant binder; silane coupling agents effectively inhibit the agglomeration of graphene and carbon nanotubes by chemical adsorption or physical coating. The results of the examples show that the conductive layer formed after the conductive carbon paste provided by the present invention is cured has excellent conductive stability and mechanical stability. DETAILED DESCRIPTION

[0020] The present invention provides a conductive carbon paste, which comprises the following components by weight: 20-30% carbon black, 5-10% graphene, 5-10% carbon nanotubes, 20-40% high temperature resistant binder, 10-20% flexibility enhancer, 2-5% silane coupling agent and the balance solvent;

[0021] The flexibility enhancer includes polyurethane or silicone.

[0022] In the present invention, unless otherwise specified, the raw materials used in the present invention are all commercially available products well known in the art.

[0023] The conductive carbon paste provided by the present invention comprises 20-30% by weight of carbon black. In one embodiment of the present invention, the weight percentage of the carbon black can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%. By adding carbon black, the present invention can fill the conductive network formed by graphene and carbon nanotubes, forming a point-to-surface conductive contact, thereby improving the conductivity of the conductive layer formed after the conductive carbon paste is cured.

[0024] In the present invention, the particle size of the carbon black is preferably 15 to 30 nm, more preferably 20 to 25 nm. The carbon black of the above particle size has a smaller particle size and a larger specific surface area, which is more conducive to filling the conductive network formed by graphene and carbon nanotubes.

[0025] The conductive carbon paste provided by the present invention includes 5-10% graphene by weight. As one embodiment of the present invention, the weight percentage of the graphene can be 5%, 6%, 7%, 8%, 9%, or 10%. By adding graphene, the two-dimensional layered structure of the present invention can form a conductive surface and can also form an excellent three-dimensional conductive network with carbon nanotubes and carbon black.

[0026] In the present invention, the graphene sheet thickness is preferably 1 to 10 nm, more preferably 1 to 5 nm. In the present invention, the graphene sheet diameter is preferably 1 to 10 μm, more preferably 5 to 8 μm. The graphene of the above size is used in the present invention, which has a larger specific surface area and is more conducive to constructing a three-dimensional conductive network.

[0027] The conductive carbon paste provided by the present invention includes 5-10% carbon nanotubes by weight. As one embodiment of the present invention, the weight percentage of the carbon nanotubes can be 5%, 6%, 7%, 8%, 9%, or 10%. The addition of carbon nanotubes in the present invention can form an excellent three-dimensional conductive network with graphene and carbon black.

[0028] In the present invention, the carbon nanotubes preferably have a diameter of 5 to 100 nm, more preferably 10 to 50 nm; and an aspect ratio of 500 to 3000, more preferably 1000 to 2000. In the present invention, the carbon nanotubes are preferably multi-walled carbon nanotubes. The use of these carbon nanotubes in the present invention further enhances the electrical conductivity and mechanical properties of the conductive carbon paste.

[0029] The conductive carbon paste provided by the present invention includes 20-40% by weight of a high-temperature resistant binder. As one embodiment of the present invention, the weight percentage of the high-temperature resistant binder can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%. By adding the high-temperature resistant binder, the present invention can enhance the adhesiveness of the conductive carbon paste, resulting in a conductive layer formed after curing of the conductive carbon paste having excellent mechanical properties.

[0030] In the present invention, the high temperature resistant adhesive preferably comprises polyimide or epoxy-acrylate copolymer. In the present invention, the polyimide has acid ester bifunctional groups, can be applied to UV and thermal dual curing process, and has excellent biocompatibility, mechanical strength and high temperature resistance. In an embodiment of the present invention, the polyimide can be photosensitive polyimide, and the model of the photosensitive polyimide can be Fujifilm 9305 / 9306.

[0031] In the present invention, the epoxy-acrylate copolymer is preferably Ebecryl 3700. The present invention uses epoxy-acrylate copolymer as a high-temperature resistant adhesive, which contains epoxy and acrylate bifunctional groups, is suitable for UV and thermal dual-curing processes, and has excellent mechanical strength and high-temperature resistance.

[0032] By weight percentage, the conductive carbon paste provided by the present invention includes 10 to 20% of a flexibility enhancer. As an embodiment of the present invention, the weight percentage of the flexibility enhancer can be 10%, 12%, 14%, 16%, 18% or 20%. In the present invention, the flexibility enhancer includes polyurethane or silicone. By adding a flexibility enhancer, the present invention can have good compatibility with the carbon materials (such as graphene, carbon black and carbon nanotubes) in the conductive carbon paste, and can improve the flexibility of the conductive layer formed after the conductive carbon paste is cured.

[0033] In terms of weight percentage, the conductive carbon paste provided by the present invention includes 2 to 5% of a silane coupling agent. As an embodiment of the present invention, the weight percentage of the silane coupling agent can be 2%, 3%, 4% or 5%. In the present invention, the silane coupling agent preferably includes one or more of γ-aminopropyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane. The present invention adds a silane coupling agent, which has an organic group and an inorganic active group, and can act as a bridge between the carbon material and the high-temperature resistant binder, thereby enhancing the interfacial affinity between the carbon nanomaterial and the high-temperature resistant binder; the coupling agent effectively inhibits the agglomeration of graphene and carbon nanotubes by chemical adsorption or physical coating, thereby improving the stability of the conductive carbon paste.

[0034] The conductive carbon paste provided by the present invention further comprises 1.5 to 3% by weight of an antioxidant. As one embodiment of the present invention, the weight percentage of the antioxidant may be 1.5%, 2%, 2.5%, or 3%. In the present invention, the antioxidant is preferably an oil-soluble phenolic antioxidant. In the present invention, the oil-soluble phenolic antioxidant is preferably Irganox 1010, Irganox 1076, or BHT. By adding an antioxidant, the present invention can effectively remove free radicals formed during the dispersion and curing process of the carbon material, prevent oxidative degradation during the thermosetting process, improve the long-term electrochemical stability of the conductive carbon paste, and thereby improve the stability of the conductive carbon paste during use.

[0035] The conductive carbon paste provided herein includes a balance of solvent, calculated by weight percentage. In the present invention, the solvent preferably comprises medical-grade ethanol or dimethylformamide. The present invention utilizes a solvent as a dispersion medium for the conductive carbon paste. The medical-grade ethanol used in the present invention has a purity of greater than or equal to 95% and exhibits good biocompatibility.

[0036] The present invention utilizes carbon black, graphene, and carbon nanotubes as conductive materials for the conductive carbon paste. The carbon nanotubes and graphene form a self-supporting three-dimensional network structure, and carbon black can be filled in the self-supporting three-dimensional network structure formed by the carbon nanotubes and graphene. In this self-supporting three-dimensional network structure, the carbon nanotubes can act as "conductors." Carbon black, graphene, and carbon nanotubes can form point-to-surface contact, thereby making the conductive carbon paste have abundant conductive pathways and excellent conductivity. At the same time, the conductive layer formed after the conductive carbon paste is cured has excellent mechanical properties, flexibility, and chemical stability. The high-temperature resistant binder can make the conductive layer formed after the conductive carbon paste is cured resistant to the high temperature of the device operation, thereby improving the mechanical stability of the conductive layer formed after the conductive carbon paste is cured. The flexibility enhancer can improve the flexibility of the conductive layer formed after the conductive carbon paste is cured. The silane coupling agent effectively inhibits the agglomeration of graphene and carbon nanotubes by chemical adsorption or physical coating.

[0037] The present invention also provides a method for preparing the conductive carbon paste described in the above technical solution, comprising the following steps:

[0038] (1) mixing carbon black, graphene, carbon nanotubes and a solvent to obtain a carbon material dispersion;

[0039] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and then subjecting the mixture to high-speed shearing to obtain a mixed slurry; the high-speed shearing speed is 5000 to 8000 rpm, and the high-speed shearing time is 40 to 60 minutes;

[0040] (3) mixing the mixed slurry obtained in step (2) with a silane coupling agent to obtain a conductive carbon slurry.

[0041] The present invention mixes carbon black, graphene, carbon nanotubes and a solvent to obtain a carbon material dispersion.

[0042] In the present invention, the carbon black, graphene, carbon nanotubes, and solvent are preferably mixed by ultrasound. The power of the ultrasound is preferably 20 to 40 kHz, more preferably 30 to 35 kHz. The duration of the ultrasound is preferably 20 to 30 minutes, more preferably 25 to 30 minutes. The use of ultrasound in the present invention is more conducive to fully dispersing the carbon black, graphene, and carbon nanotubes in the solvent, thereby obtaining a uniformly dispersed carbon material dispersion.

[0043] After obtaining the carbon material dispersion, the present invention mixes the carbon material dispersion with a high temperature resistant binder and a flexibility enhancer and then performs high-speed shearing to obtain a mixed slurry.

[0044] In the present invention, the rotation speed of the high-speed shear is 5000-8000 rpm. As an embodiment of the present invention, the rotation speed of the high-speed shear can be 5000 rpm, 5500 rpm, 6000 rpm, 6500 rpm, 7000 rpm, 7500 rpm or 8000 rpm. In the present invention, the time of the high-speed shear is 40-60 min. As an embodiment of the present invention, the time of the high-speed shear can be 40 min, 45 min, 50 min, 55 min or 60 min. The strong fluid dynamics generated by the high-speed shearing can effectively break the van der Waals force between the graphene sheets, reduce agglomeration, and make the high-temperature resistant binder and flexibility enhancer uniformly dispersed in the three-dimensional conductive network of carbon black, graphene and carbon nanotubes, thereby improving the dispersion and stability of the mixed slurry.

[0045] After obtaining the mixed slurry, the present invention mixes the mixed slurry with a silane coupling agent to obtain a conductive carbon slurry.

[0046] In the present invention, the mixed slurry and the silane coupling agent are preferably mixed by stirring. The present invention does not particularly limit the speed and time of the stirring. Conventional mechanical stirring speed can be adjusted to uniformly mix the mixed slurry, the silane coupling agent, and the antioxidant. In an embodiment of the present invention, the stirring time is preferably 10 to 15 minutes, more preferably 12 to 15 minutes.

[0047] In the present invention, when the conductive carbon paste includes an antioxidant, the mixed paste, silane coupling agent and antioxidant are mixed in the same manner as the method of mixing the mixed paste and silane coupling agent in the above technical solution.

[0048] The preparation method provided by the present invention is simple to operate and can make the components evenly distributed in the solvent, thereby forming a stably dispersed conductive carbon paste with high dispersibility and stability.

[0049] The present invention also provides the use of the conductive carbon paste described in the above technical solution in medical electronic devices and bioelectronic devices.

[0050] The present invention has no special limitation on the method of applying the conductive carbon paste in medical electronic devices and bioelectronic devices, and any conventional method of applying the conductive carbon paste can be used.

[0051] In the present invention, the conductive carbon paste is preferably applied to medical electronic devices and bioelectronic devices by forming a coating and then curing it. In an embodiment of the present invention, the conductive carbon paste can be applied to a medical electronic device or bioelectronic device by coating the conductive carbon paste on a substrate of a medical device port, first thermally curing it, and then irradiating it with UV light to form a dense conductive layer.

[0052] In the present invention, the coating thickness is preferably 20 to 50 μm.

[0053] In the present invention, the thermal curing temperature may be 80° C. and the thermal curing time may be 20 minutes.

[0054] In the present invention, the wavelength of the UV light may be 365 nm; and the UV light irradiation time may be 5 to 10 minutes.

[0055] The conductive carbon paste provided by the present invention has excellent electrical conductivity and mechanical properties, and can therefore be used in medical electronic devices and bioelectronic devices.

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0057] The particle size of the carbon black used in the embodiments of the present invention is 20-30 nm; the thickness of the graphene sheet is 1-2 nm; the diameter of the graphene sheet is 1-5 μm; the diameter of the carbon nanotube is 5-20 nm; and the aspect ratio of the carbon nanotube is greater than 1000.

[0058] Example 1

[0059] A conductive carbon paste, the components of which are, by weight percentage, 25% carbon black, 8% graphene, 7% carbon nanotubes, and a high temperature resistant binder polyimide (Fujifilm 9305) 30%, flexible enhancer polyurethane ( 2102) 15%, silane coupling agent (KH550) 3% and solvent ethanol 12%;

[0060] The preparation method of the conductive carbon paste is:

[0061] (1) ultrasonically treating carbon black, graphene, carbon nanotubes, and a solvent at 40 kHz for 30 min to obtain a carbon material dispersion;

[0062] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and subjecting the mixture to high-speed shearing at 8000 rpm for 60 minutes to obtain a mixed slurry;

[0063] (3) The mixed slurry obtained in step (2) is stirred and mixed with a silane coupling agent to obtain a conductive carbon slurry.

[0064] Example 2

[0065] A conductive carbon paste, comprising, by weight percentage, 20% carbon black, 10% graphene, 5% carbon nanotubes, 30% high-temperature resistant binder Ebecryl 3700, 15% flexibility enhancer silicone, 3% silane coupling agent (KH550), 2% antioxidant (BHT), and 15% solvent DMF;

[0066] The preparation method of the conductive carbon paste is:

[0067] (1) ultrasonically treating carbon black, graphene, carbon nanotubes, and solvent at 20 kHz for 20 min to obtain a carbon material dispersion;

[0068] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and subjecting the mixture to high-speed shearing at 5000 rpm for 40 minutes to obtain a mixed slurry;

[0069] (3) The mixed slurry obtained in step (2) is stirred and mixed with a silane coupling agent and an antioxidant to obtain a conductive carbon slurry.

[0070] Example 3

[0071] A conductive carbon paste, the components of which are, by weight percentage, 30% carbon black, 5% graphene, 10% carbon nanotubes, and a high temperature resistant binder polyimide (Fujifilm 9305) 25%, flexible enhancer polyurethane ( 2102) 20%, silane coupling agent (KH550) 4% and solvent ethanol 6%;

[0072] The preparation method of the conductive carbon paste is:

[0073] (1) ultrasonically treating carbon black, graphene, carbon nanotubes, and solvent at 30 kHz for 25 min to obtain a carbon material dispersion;

[0074] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and then high-speed shearing the mixture at 6000 rpm for 50 minutes to obtain a mixed slurry;

[0075] (3) The mixed slurry obtained in step (2) is stirred and mixed with a silane coupling agent to obtain a conductive carbon slurry.

[0076] Example 4

[0077] A conductive carbon paste, comprising, by weight percentage, 22% carbon black, 7% graphene, 8% carbon nanotubes, 28% high-temperature resistant binder Ebecryl 3700, 20% flexibility enhancer silicone, 3% silane coupling agent (KH550), 3% antioxidant (BHT), and 9% solvent DMF;

[0078] The preparation method of the conductive carbon paste is:

[0079] (1) ultrasonically treating carbon black, graphene, carbon nanotubes, and a solvent at 40 kHz for 30 min to obtain a carbon material dispersion;

[0080] (2) mixing the carbon material dispersion obtained in step (1) with a high temperature resistant binder and a flexibility enhancer, and subjecting the mixture to high-speed shearing at 7000 rpm for 60 minutes to obtain a mixed slurry;

[0081] (3) The mixed slurry obtained in step (2) is stirred and mixed with a silane coupling agent and an antioxidant to obtain a conductive carbon slurry.

[0082] Example 5

[0083] A conductive carbon paste, the components of which are, by weight percentage, 28% carbon black, 6% graphene, 6% carbon nanotubes, and a high temperature resistant binder polyimide (Fujifilm 9305) 32%, flexible enhancer polyurethane ( 2102) 15%, silane coupling agent (KH550) 3% and solvent ethanol 10%;

[0084] The preparation method of the conductive carbon paste is:

[0085] (1) ultrasonically treating carbon black, graphene, carbon nanotubes, and solvent at 30 kHz for 20 min to obtain a carbon material dispersion;

[0086] (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and then high-speed shearing the mixture at 8000 rpm for 50 minutes to obtain a mixed slurry;

[0087] (3) The mixed slurry obtained in step (2) is stirred and mixed with a silane coupling agent to obtain a conductive carbon slurry.

[0088] Comparative Example 1

[0089] A conductive carbon paste, comprising, by weight percentage, 40% carbon black, 50% phenolic resin (SJ-2029) and 10% ethanol;

[0090] The conductive carbon paste is prepared by stirring carbon black, phenolic resin and ethanol at a rotation speed of 3000 rpm for 30 minutes to obtain the conductive carbon paste.

[0091] Comparative Example 2

[0092] A conductive carbon paste, comprising, by weight percentage, 20% graphene, 60% polyester resin (HDP-700) and 10% DMF;

[0093] The conductive carbon paste is prepared by stirring graphene, polyester resin and DMF at a rotation speed of 4000 rpm for 40 minutes to obtain the conductive carbon paste.

[0094] Comparative Example 3

[0095] A conductive carbon paste, comprising, by weight percentage, 30% carbon black, 10% carbon nanotubes, 50% epoxy resin E-44, and 10% ethanol;

[0096] The conductive carbon paste is prepared by stirring carbon black, carbon nanotubes, epoxy resin and ethanol at a rotation speed of 350 rpm for 50 minutes to obtain the conductive carbon paste.

[0097] Application Example 1

[0098] The conductive carbon paste obtained in Example 1 was inkjet printed on a medical device port substrate with a coating thickness of 30 μm; it was first thermally cured at 80° C. for 20 minutes, and then irradiated with UV light with a wavelength of 365 nm for 10 minutes to obtain a conductive layer.

[0099] Application Example 2

[0100] The conductive carbon paste obtained in Example 2 was inkjet printed on a medical device port substrate with a coating thickness of 20 μm; it was first thermally cured at 80° C. for 15 minutes, and then irradiated with UV light with a wavelength of 365 nm for 5 minutes to obtain a conductive layer.

[0101] Application Example 3

[0102] The conductive carbon paste obtained in Example 3 was inkjet printed on a medical device port substrate with a coating thickness of 50 μm; it was first thermally cured at 80° C. for 25 minutes, and then irradiated with UV light with a wavelength of 365 nm for 8 minutes to obtain a conductive layer.

[0103] Application Example 4

[0104] The conductive carbon paste obtained in Example 4 was inkjet printed on a medical device port substrate with a coating thickness of 40 μm; it was first thermally cured at 80° C. for 20 min, and then irradiated with UV light with a wavelength of 365 nm for 10 min to obtain a conductive layer.

[0105] Application Example 5

[0106] The conductive carbon paste obtained in Example 5 was inkjet printed on a medical device port substrate with a coating thickness of 25 μm; it was first thermally cured at 80° C. for 15 minutes, and then irradiated with UV light with a wavelength of 365 nm for 7 minutes to obtain a conductive layer.

[0107] Comparative Application Example 1

[0108] The screen-printed coating obtained in Comparative Example 1 had a thickness of 50 μm and was thermally cured at 120° C. for 30 minutes.

[0109] Comparative Application Example 2

[0110] The screen-printed coating obtained in Comparative Example 2 had a thickness of 40 μm and was thermally cured at 100° C. for 25 minutes.

[0111] Comparative Application Example 3

[0112] The screen-printed coating obtained in Comparative Example 3 had a thickness of 30 μm and was thermally cured at 110° C. for 20 min.

[0113] Test Case

[0114] The performance of the conductive coatings obtained from Examples 1 to 5 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 1:

[0115] Table 1 Performance test results of the conductive coatings obtained in Application Examples 1 to 5 and Comparative Application Examples 1 to 3

[0116]

[0117]

[0118] From the above results, it can be seen that the conductive layer formed after the conductive carbon paste provided by the present invention is cured has excellent electrical conductivity and mechanical properties, and after high temperature and high humidity treatment, or bending test, it still has excellent electrical conductivity and mechanical properties, and the electrical conductivity and mechanical stability are good. This is due to the fact that the present invention uses carbon black, graphene and carbon nanotubes as conductive materials of the conductive carbon paste to form a self-supporting three-dimensional network structure with excellent electrical conductivity. In addition, both graphene and carbon nanotubes have excellent mechanical properties, flexibility and chemical stability, which can improve the mechanical stability of the conductive layer formed after the conductive carbon paste is cured. The high temperature resistant binder can improve the high temperature resistance of the conductive layer formed after the conductive carbon paste is cured. The flexibility enhancer can improve the flexibility of the conductive layer formed after the conductive carbon paste is cured. The silane coupling agent can act as a bridge between the carbon material and the high temperature resistant binder, enhancing the interfacial affinity between the carbon nanomaterial and the high temperature resistant binder; the silane coupling agent effectively inhibits the agglomeration of graphene and carbon nanotubes by chemical adsorption or physical coating. Therefore, the conductive layer formed after the conductive carbon paste provided by the present invention is cured has excellent electrical conductivity and mechanical property stability.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A conductive carbon paste comprising the following components, by weight percentage: 20-30% carbon black, 5-10% graphene, 5-10% carbon nanotubes, 20-40% high temperature resistant binder, 10-20% flexibility enhancer, 2-5% silane coupling agent, and the balance solvent; The flexibility enhancer includes polyurethane or silicone.

2. The conductive carbon paste according to claim 1, characterized in that The particle size of the carbon black is 15 to 30 nm.

3. The conductive carbon paste according to claim 1, characterized in that The thickness of the graphene sheet is 1 to 10 nm; the diameter of the graphene sheet is 1 to 10 μm.

4. The conductive carbon paste according to claim 1, characterized in that The diameter of the carbon nanotube is 5-100 nm; the aspect ratio of the carbon nanotube is 500-3000.

5. The conductive carbon paste according to claim 1, characterized in that The high temperature resistant adhesive includes polyimide or epoxy-acrylate copolymer.

6. The conductive carbon paste according to claim 5, characterized in that The model of the epoxy-acrylate copolymer is Ebecryl 3700.

7. The conductive carbon paste according to claim 1, characterized in that The silane coupling agent includes one or more of γ-aminopropyltriethoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

8. The conductive carbon paste according to claim 1, wherein: The conductive carbon paste further includes an antioxidant, which is an oil-soluble phenol antioxidant.

9. The method for preparing the conductive carbon paste according to any one of claims 1 to 8, comprising the following steps: (1) mixing carbon black, graphene, carbon nanotubes and a solvent to obtain a carbon material dispersion; (2) mixing the carbon material dispersion obtained in step (1) with a high-temperature resistant binder and a flexibility enhancer, and then subjecting the mixture to high-speed shearing to obtain a mixed slurry; the high-speed shearing speed is 5000 to 8000 rpm, and the high-speed shearing time is 40 to 60 minutes; (3) mixing the mixed slurry obtained in step (2) with a silane coupling agent to obtain a conductive carbon slurry.

10. Use of the conductive carbon paste according to any one of claims 1 to 8 or the conductive carbon paste prepared by the preparation method according to claim 9 in medical electronic devices and bioelectronic devices.

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