Surface-modified IRGO-coated Ni high-conductivity ink material, preparation method thereof and conductive ink

Abstract

The invention belongs to the field of new materials, and discloses a preparation method of a surface-modified IRGO-coated Ni high-conductivity ink material, which comprises the following steps: step 1, under the action of an electric field, preparing a composite material GO-coated Ni of graphene oxide coated nickel powder by taking graphene oxide and spherical nickel powder as raw materials; and 2, the composite material GO (at) Ni is reduced, and a composite material RGO (at) Ni of graphene coated nickel powder is obtained. According to the method, the GO-coated Ni is prepared by adopting an electric field deposition method, and then the GO-coated Ni is reduced and modified to obtain the composite material which is good in electric conductivity and not prone to oxidative deterioration. Meanwhile, the invention further discloses the composite material prepared based on the method and the conductive ink.

Description

Technical Field

[0001] The present invention relates to the field of new materials, and specifically to a surface-modified IRGO@Ni highly conductive ink material, a preparation method thereof, and a conductive ink. Background Art

[0002] Conductive ink refers to a paste ink made by dispersing conductive materials (gold, silver, copper, and carbon) in a binder, and is widely used in fields such as printed circuits, membrane switches, RFID, semiconductor packaging, and solar cells. With the rapid development of conductive ink, the currently applicable conductive ink not only needs to have functions such as information transmission and color presentation, but also needs to have special properties: such as safety, degradability, conductivity, magnetism, etc. In particular, the safety, environmental protection, and conductivity of the ink are of top priority.

[0003] Conductive filler is the key functional phase of conductive ink. According to the nature of the conductive filler, conductive ink can be divided into inorganic, metal, and organic systems. Among them, the metal system selects gold-based, silver-based, or copper-based materials. The various properties of gold-based conductive ink are very excellent, but its price is expensive, and its use is greatly restricted; copper-based conductive ink has high cost performance, but copper powder is easy to oxidize; although silver-based has good high conductivity and chemical stability, there is a problem of electron migration in silver conductive circuits, and at the same time, silver also belongs to one of the precious metals, and its cost is 3-5 times that of conventional metals, which leads to a relatively high cost of selecting inorganic nano-metal conductive ink, restricting its application in the field of electronic materials. Compared with metal-based conductive ink, inorganic (carbon-based) conductive ink is relatively cheap, but the conductivity and corrosion resistance of the carbon-based are inferior to those of metals. Organic conductive ink contains pungent odors, and the volatile substances contain harmful substances to the human body, and the odor volatilization period is long. Therefore, new composite conductive ink is an important development direction of current conductive ink fillers. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a surface-modified IRGO@Ni highly conductive ink material. This method uses an electric field deposition method to prepare GO@Ni, and then through reduction, a composite material with good conductivity and not easily oxidized and deteriorated is obtained.

[0005] At the same time, the present invention also discloses the composite material and conductive ink prepared based on this method.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A preparation method of a surface-modified IRGO@Ni highly conductive ink material, comprising the following steps:

[0008] Step 1: Under the action of an electric field, a composite material GO@Ni of graphene oxide-coated nickel powder is prepared using graphene oxide and spherical nickel powder as raw materials;

[0009] Step 2: The composite material GO@Ni is reduced to obtain a composite material RGO@Ni of reduced graphene oxide-coated nickel powder.

[0010] Preferably, it further includes Step 3: A grafting group with unsaturated double bonds is loaded on the surface of the composite material RGO@Ni to obtain a composite material IRGO@Ni.

[0011] The core innovation of the present invention lies in:

[0012] 1. By using an electric field, graphene oxide-coated nickel powder is achieved through a non-electrochemical method;

[0013] The present invention is different from the traditional electrolysis / electroplating method. The present invention does not involve the reduction of metal ions. Only the enrichment of nickel particles is achieved through an electric field, and assembly is completed at the position where nickel particles are enriched through the electrostatic adsorption characteristics of graphene oxide; this composite material prepared based on the weak adsorption principle of the electric field (Guglielmi et al. first proposed a two-step adsorption theory for particles during electrodeposition, that is, adsorption experiences two stages: weak adsorption and strong adsorption. In the weak adsorption stage, metal ions can be adsorbed around the particles, and the latter, with the help of the ion groups adsorbed on its surface, is loosely adsorbed on the cathode surface under the action of electrostatic force. This process is reversible, and the adsorption state of the particles on the cathode can be affected by external forces and thus detached from the cathode surface. Guglielmi N. Kinetics of the deposition of inert particles from electrolytic baths[J]. Journal of the Electrochemical Society, 1972, 119(8): 1009., this weak adsorption principle is further confirmed in Section 2.3 of the master's thesis "Study on the Preparation Process and Antibacterial Properties of Graphene Oxide-Modified Nickel Coatings by Electrodeposition", which deposits a dense coating on the electrode plate through the assembly of graphene and nickel powder and the reduction of nickel ions) and the electrostatic adsorption principle of graphene has a uniform three-dimensional network structure. Through the three-dimensional network and void channels, it can be used for electron transfer, further increasing the conductivity of the material; the conductivity of the composite material obtained by the method of the present invention is far superior to that of the composite material obtained by the solution self-assembly method in the prior art.

[0014] At the same time, once the composite material GO@Ni of the present invention is completely covered by graphene oxide in an electric field, its surface becomes insulating and difficult to contact with the graphene oxide in the solution, so that the particle size uniformity of all the composite materials GO@Ni can be kept high, thereby improving the performance in subsequent applications.

[0015] 2. The present invention reduces and modifies the graphene on the surface of the composite material;

[0016] By grafting organic matter with unsaturated groups, the compatibility of the composite material and the resin is improved, and the double bond structure is used as a chemical crosslinking point in the subsequent synthesis of the conductive ink to form a stable chemical crosslinking network with polyimide and acrylic soluble resins. The existence of the chemical crosslinking network makes the position of the composite material IRGO@Ni in the conductive ink relatively fixed, improving the stability and uniformity of the conductive ability of the conductive ink at all locations; on the other hand, the RGO on the surface of the composite material IRGO@Ni can form intramolecular and intermolecular hydrogen bonds with resin binders (vinyl chloride resin, acrylic resin, polyester resin, polyimide resin), forming a stable three-dimensional network structure, improving the mechanical properties of the conductive ink, that is, enhancing the rigidity and mechanical properties of the conductive ink.

[0017] Through the above optimization and transformation, a composite material can be obtained which is highly compatible with the resin in the ink, has good conductivity and is not easily oxidized and deteriorated.

[0018] In the above preparation method, the width of the graphene oxide sheet is 100-200 nm; the diameter of the spherical nickel powder is 40-75 μm.

[0019] In the above preparation method, the step 1 is specifically:

[0020] Step 11: adding an electroplating solution containing graphene oxide, spherical nickel powder and a conductive agent into an electrolytic cell; applying a voltage of 3.5 to 4.5 V to the electrode plate in the electrolytic cell; a current of 15 to 35 A; and an electroplating time of 30 to 60 min;

[0021] Step 12: Collect the sediment obtained after the treatment in step 11, wash and dry it to obtain the composite material GO@Ni.

[0022] In the above-mentioned preparation method, the electroplating solution contains 0.1-0.5 mg / mL of graphene oxide, 2-4 mg / mL of spherical nickel powder, and 1-2 mg / mL of a conductive agent;

[0023] The conductive agent is a soluble metal salt, and the cations of the soluble metal salt are not reduced under an electric field.

[0024] As a further preference of the present invention, the present invention also develops an electrolytic cell based on the electric field assembly of a composite material particularly suitable for the present invention. Several pairs of electrode plates are provided in the electrolytic cell; each pair of electrode plates includes a cathode electrode plate and an anode electrode plate, both of which are inert electrodes, and the material is a titanium alloy plate with a ruthenium-iridium alloy coating.

[0025] Specifically, at least one flow channel structure in the electrolytic cell is a Tesla valve structure or a flow channel similar to the Tesla valve structure; both ends of the electrolytic cell are a liquid inlet and a liquid outlet; the liquid inlet and the liquid outlet realize the liquid circulation in the electrolytic cell through a pump; the liquid inlet is used to input the composite solution to the inlet of the flow channel; the composite solution discharged from the outlet of the flow channel is discharged through the liquid outlet; the flow channel is composed of a main flow channel and a secondary flow channel, most of the liquid in the electroplating solution flows through the main flow channel, and a small part of the liquid in the electroplating solution flows through the secondary flow channel; the cathode electrode plate and the anode electrode plate are arranged in the secondary flow channel.

[0026] By adopting a flow channel with a Tesla valve structure or a flow channel similar to the Tesla valve structure, most of the liquid flows through the main flow channel, and a small part of the liquid flows through the secondary flow channel. The flow rate of the liquid in the secondary flow channel is lower than that of the main flow channel, and the cathode electrode plate and the anode electrode plate are in the secondary flow channel, which is more conducive to the uniform coating and assembly of graphene oxide and nickel particles.

[0027] Preferably, due to the above-mentioned circulating flow structure design of the electrolytic cell, during the working process, as the composite process progresses, the insulating particles coated with graphene in the solution further increase. In order to further improve the distribution uniformity of graphene oxide and nickel particles in the electrolytic cell, a plurality of baffle structures are arranged in the electrolytic cell to facilitate fluid mixing. Specifically, the flow channel is composed of a number of first baffle plates, second baffle plates, and third baffle plates; the second baffle plate and the third baffle plate form the secondary flow channel; the first baffle plate is located on one side of the second baffle plate and the third baffle plate; the first baffle plate and the second baffle plate, the first baffle plate and the third baffle plate form the main flow channel; an aeration module is provided below the cathode and the anode; the aeration module is used to provide an inert gas to the composite solution flowing through the cathode and the anode. The aeration module can improve the suspension performance of nickel powder, increase the contact probability between nickel powder and graphene oxide, improve the coating uniformity, and avoid the problem of reduced coating uniformity caused by the deposition of nickel powder due to excessive density.

[0028] In the above preparation method, the reduction method in step 2 is wet reduction or dry reduction;

[0029] The method of wet reduction is: using sodium borohydride as a reducing agent, in an alkaline solution, reducing the composite material GO@Ni to obtain the composite material RGO@Ni;

[0030] The dry reduction method is as follows: sintering is carried out in a reducing atmosphere to obtain the composite material RGO@Ni.

[0031] In the above preparation method, step 3 is specifically as follows: the composite material RGO@Ni is added to the vinylimidazole ionic liquid for reaction so that the vinylimidazole ionic liquid can be loaded on the surface of the composite material RGO@Ni to obtain the composite material IRGO@Ni.

[0032] The mechanism of the combination of imidazole-based ionic liquid and graphene is that the cation-π interaction occurs between the imidazolium ion and the π electron cloud of graphene for combination; the vinylimidazole ionic liquid can be prepared by using a linear halogenated alkane or a chloroester as an alkylating agent to carry out an alkylation reaction with N-vinylimidazole under microwave irradiation.

[0033] The combination of the vinylimidazole ionic liquid and the resin based on the unsaturated group is based on covalent bond connection, and its connection is stable. However, in the ink system, in the absence of a radical initiator, this process is relatively slow, and more reactions occur after coating and film formation; but this does not mean that this reaction will not occur during the preparation of the ink. During the storage process (10 days), we found that the vinylimidazole ionic liquid can effectively improve the suspension stability compared with the saturated imidazole ionic liquid.

[0034] In addition, the present invention also discloses a composite material IRGO@Ni, which is prepared by using any one of the above methods.

[0035] Finally, the present invention also discloses a conductive ink, which comprises the composite material IRGO@Ni as described above, a resin for ink, a dispersant, and a solvent; the dosage of the composite material IRGO@Ni is 30-45 wt%.

[0036] In the above conductive ink, the weight ratio of the resin, the dispersant, and the solvent is 40-85:5-13:100.

[0037] In the above conductive ink, the resin is one or a mixture of a photosensitive resin, a vinyl chloride-vinyl acetate resin, an acrylic resin, a polyester resin, and a polyimide resin in any proportion.

[0038] The dispersant is one or a combination of polyethylene glycol, methyl cellulose, ethyl cellulose, and polyvinylpyrrolidone (PVP).

[0039] The solvent is one or several of water, ethanol, acetone, N,N-dimethylformamide, NMP, ethyl acetate, and a dicarboxylic acid ester.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] The present invention realizes the coating of nickel powder with graphene oxide by means of an electric field through a non-electrochemical method, reduces and modifies the graphene on the surface of the composite material, and obtains a composite material with consistent specifications, high compatibility with the resin in the ink, good conductivity, and not easily oxidized and deteriorated. Description of the Drawings

[0042] Figure 1 It is a schematic structural diagram of the electrolytic cell of Equipment Embodiment 1 of the present invention;

[0043] Figure 2 It is a schematic structural diagram of the electrolytic cell of Equipment Embodiment 9 of the present invention. Detailed Embodiments

[0044] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] The structure of the electrolytic cell used in the present invention is as shown in the equipment embodiments below.

[0046] Equipment Embodiment

[0047] Reference Figure 1 , an electrolytic cell, which is provided with 2 flow channels with a flow channel structure of a Tesla valve structure or a flow channel similar to the Tesla valve structure 1; both ends of the electrolytic cell are a liquid inlet 2 and a liquid outlet 3; the liquid inlet 2 and the liquid outlet 3 realize the liquid circulation in the electrolytic cell through a pump 4; the electroplating solution in the electrolytic cell is always in a flowing state; the liquid inlet 2 is used to input the electroplating solution to the inlet of the flow channel 1; the electroplating solution discharged from the outlet of the flow channel 1 is discharged through the liquid outlet 3.

[0048] The flow channel 1 is composed of a main flow channel 5 and a secondary flow channel 6. Most of the liquid in the electroplating solution flows through the main flow channel 5, and a small part of the liquid in the electroplating solution flows through the secondary flow channel 6; the cathode electrode plate 10 and the anode electrode plate 11 are arranged in the secondary flow channel 6.

[0049] The flow channel 1 is composed of a plurality of first guide plates 7, second guide plates 8, and third guide plates 9; the second guide plates 8 and the third guide plates 9 constitute the secondary flow channel 6; the first guide plates 7 are located on one side of the second guide plates 8 and the third guide plates 9; the first guide plates 7 and the second guide plates 8, and the first guide plates 7 and the third guide plates 9 constitute the main flow channel 5;

[0050] The first guide plates 7 are arranged in two columns in a fishbone form, and there is also fluid flow in the middle of the two columns of first guide plates 7, so comprehensivelyFigure 1 It can be seen that the fluid flow patterns of the present invention are generally divided into the flow in the flow channel 1 based on the Tesla valve structure and the fluid flow between the two rows of the first guide plates 7. Among them, in these two flow patterns, there is a part of the liquid flowing from the flow channel 1 of the Tesla valve structure into the space between the two rows of the first guide plates 7, and flowing from the space between the two rows of the first guide plates 7 into the flow channel 1 of the Tesla valve structure. However, the overall flow pattern is still mainly based on the flow channel 1 of the Tesla valve structure.

[0051] Both the cathode electrode plate 10 and the anode electrode plate 11 are inert electrode plates, specifically titanium alloy plates with a ruthenium-iridium alloy coating. Both the cathode electrode plate 10 and the anode electrode plate 11 are vertically arranged.

[0052] More specifically, in the embodiments described below, the specific parameters of the electrolytic cell of the present invention used (in actual applications, relevant parameters can be adjusted according to factors such as production scale, and the actual protection scope is not limited to the following specific structural parameters) are as follows:

[0053] Electrolytic cell:

[0054] Length: 56 cm; width: 45 cm; height: 16 cm;

[0055] The first guide plate 7: 9 cm

[0056] The second guide plate 8: 5 cm

[0057] The third guide plate 9: 16 cm

[0058] The distance between the second guide plate 8 and the third guide plate 9 is: 5 cm; the distance between the main flow channel 5 and the secondary flow channel 6 is similar.

[0059] Both the cathode electrode plate 10 and the anode electrode plate 11 are titanium alloy plates with a ruthenium-iridium alloy coating; the distance between the cathode electrode plate 10 and the anode electrode plate 11 is: 4 cm; the volume of the electroplating solution accommodated in the electrolytic cell is: 30000 cm 3 ; the circulation volume of the pump 44 during operation is: 8 - 12 L / h.

[0060] Example 1

[0061] S1: Preparation of GO@Ni composite material

[0062] S11: Preparation of electroplating solution A: Weigh 30 mg of GO, add it to 100 mL of deionized water, and perform ultrasonic treatment for 4 h to form a uniform and stable GO dispersion with a concentration of 0.3 mg / mL. Among them, the D50 particle size of GO is about 110 nm. Then add 300 mg of spherical nickel powder (D50 particle size is about 40 μm) and 200 mg of conductive agent (Na2SO4) to the above GO dispersion, stir evenly and perform ultrasonic dispersion to obtain a uniformly mixed electroplating solution A.

[0063] Note: The preparation method of GO is as follows: After pulverizing graphene oxide, place it in a grinding machine, and the grinding balls used for grinding are zirconia beads. Control the particle size by controlling the grinding time. Continuously sample and analyze the D50 particle size. When the requirement is met, discharge the material. The particle size of the zirconia beads can be selected within the range of 0.5 to 1.5 μm.

[0064] S12: Preparation of GO@Ni composite material: Prepare the GO@Ni composite material by electrodeposition method. Pour the electroplating solution A into the electrolytic cell described in the above device embodiment. The electroplating electrodes of the electrolytic cell are respectively connected to the positive and negative electrodes of an external power supply. The voltage, current and electroplating time of the electrodes are: voltage 4 V, current 20 A, electroplating time 45 min, and synthesize the GO@Ni composite material. During the electroplating process, the temperature of the electrolytic cell is controlled at 30 °C.

[0065] S2: Surface treatment of GO@Ni composite material (preparation of IRGO@Ni composite material)

[0066] S21: Select 200 mg of the synthesized composite material GO@Ni and ultrasonically disperse it in 200 mL of NaOH aqueous solution with a pH of 11 to obtain a yellowish-brown colloidal suspension B.

[0067] S22: Then mix the colloidal suspension B, 1.45 g of sodium borohydride (NaBH4), 150 mL of N-vinylimidazole ionic liquid, and 150 mL of dimethyl sulfoxide (DMSO) to obtain solution C. Solution C is continuously stirred for 12 h to obtain a composite material IRGO@Ni that has been fully reduced and loaded with vinylimidazole.

[0068] Filter the above solution C, wash the filter residue, and dry it to obtain the dried composite material IRGO@Ni.

[0069] S3: Preparation of conductive ink

[0070] S31: Select 60 parts by weight of acrylic resin (viscosity: 2000 - 13000 mPa·s at 25 °C, pH 6.5 - 8.5, solid content 32%), 10 parts by weight of polyvinylpyrrolidone, and 100 parts by weight of N,N-dimethylformamide and dissolve them evenly to obtain a conductive ink binder D.

[0071] S32: Mix the conductive filler IRGO@Ni and the conductive ink binder D evenly by stirring in a water bath at a mass ratio of 30:70, where the water bath temperature is 85 °C and the stirring time is 5 h, thus obtaining the IRGO@Ni conductive ink.

[0072] Example 2

[0073] Generally the same as Example 1, the differences are as follows:

[0074] In S11, the concentrations of the substances contained in the electroplating solution A are: GO: 0.1 mg / mL, nickel powder: 2 mg / mL; conductive agent: 1 mg / mL; the D50 particle size of GO is about 150 nm; the D50 particle size of spherical nickel powder is about 60 μm;

[0075] In S12, the voltage is 3.5 V, the current is 15 A, and the electroplating time is 30 min;

[0076] In S31, 40 parts by weight of acrylic resin, 5 parts by weight of polyvinylpyrrolidone, and 100 parts by weight of N,N-dimethylformamide;

[0077] In S32, the mass ratio of the conductive filler IRGO@Ni to the conductive ink binder D is 45:55.

[0078] Example 3

[0079] Generally the same as Example 1, the differences are as follows:

[0080] In S11, the concentrations of the substances contained in the electroplating solution A are: GO: 0.5 mg / mL, nickel powder: 4 mg / mL; conductive agent: 2 mg / mL; the D50 particle size of GO is about 180 nm; the D50 particle size of spherical nickel powder is about 75 μm;

[0081] In S12, the voltage is 4.5 V, the current is 35 A, and the electroplating time is 60 min;

[0082] In S31, 85 parts by weight of acrylic resin, 13 parts by weight of polyvinylpyrrolidone, and 100 parts by weight of N,N-dimethylformamide;

[0083] In S32, the mass ratio of the conductive filler IRGO@Ni to the conductive ink binder D is 40:60.

[0084] Example 4

[0085] Generally the same as Example 1, the differences are as follows:

[0086] In S11, the concentrations of the substances contained in the electroplating solution A are: GO: 0.5 mg / mL, nickel powder: 2 mg / mL; conductive agent: 1 mg / mL;

[0087] In S12, the voltage is 3.5 V, the current is 20 A, and the electroplating time is 40 min;

[0088] In S31, 60 parts by weight of an acrylic resin, 10 parts by weight of polyvinylpyrrolidone, and 100 parts by weight of N,N-dimethylformamide;

[0089] In S32, the mass ratio of the conductive filler IRGO@Ni to the conductive ink binder D is 35:65.

[0090] Example 5

[0091] Substantially the same as Example 1, except that:

[0092] The sheet width of graphene oxide is submicron-sized, its D50 particle size is about 500 nm, and the D50 particle size of spherical nickel powder is about 40 μm.

[0093] Example 6

[0094] Substantially the same as Example 1, except that:

[0095] The sheet width of graphene oxide is submicron-sized, its D50 particle size is about 500 nm, and the D50 particle size of spherical nickel powder is about 150 μm.

[0096] Example 7

[0097] Substantially the same as Example 1, except that:

[0098] The D50 particle size of graphene oxide is about 110 nm, and the D50 particle size of spherical nickel powder is about 30 μm.

[0099] Example 8

[0100] Substantially the same as Example 1, except that:

[0101] The D50 particle size of graphene oxide is about 110 nm, and the D50 particle size of spherical nickel powder is about 20 μm.

[0102] Example 9

[0103] Substantially the same as Example 1, except that:

[0104] The cathode plate and the anode plate are arranged in the main flow channel, specifically referring to Figure 2 .

[0105] Example 10

[0106] Substantially the same as Example 1, except that Step 2 is specifically as follows:

[0107] S2: Reduction and surface treatment of GO@Ni composite materials (preparation of IRGO@Ni composite materials)

[0108] S21: Preparation of RGO@Ni: The obtained GO@Ni is calcined under a reducing atmosphere, which is a mixed gas of a reducing gas and an inert protective gas (the volume ratio of H2 to N2 is 6:1). The GO@Ni powder is heated from room temperature to 300 °C at a rate of 5 °C / min and maintained at this temperature for 60 min; then it is rapidly heated to 900 °C (10 °C / min), and then thermally annealed at this temperature for 2 h; finally, the powder is naturally cooled to room temperature to obtain the RGO@Ni composite material.

[0109] S22: Preparation of IRGO@Ni: 100 mL of N-vinylimidazole is added to 150 ml of dimethyl sulfoxide (DMSO); then 200 mg of the RGO@Ni composite material is added to the above solution, and it is continuously stirred at 35 °C for 12 h until a stable black solution is obtained; after filtering and washing multiple times with water and acetone, the final product IRGO@Ni after reduction and surface modification treatment is obtained.

[0110] Comparative Example 1

[0111] Generally the same as Example 1, the difference is that:

[0112] In the above electrolytic cell, the anode electrode plate and the cathode electrode plate are not energized, and the composite material is prepared by the method of solution self-assembly.

[0113] Comparative Example 2

[0114] Generally the same as Example 1, the difference is that:

[0115] 1-Ethyl-3-methylimidazolium chloride ionic liquid is used to replace the vinylimidazole ionic liquid in equal weight.

[0116] Sample preparation

[0117] The conductive inks prepared in each example and comparative example are diluted to (40% wt) and coated on a glass sheet (6×12 cm 2 ) and dried; the ink film is observed under a microscope to judge its dispersion performance and conductivity test.

[0118] Dispersion test:

[0119] If the dispersion state of the conductive ink slurry is good, the particle distribution is uniform, the arrangement is dense, and the agglomeration phenomenon is rare, it is evaluated as 5 points;

[0120] If the dispersion state of the conductive ink slurry is poor, the particle distribution is concentrated, the arrangement is loose, and the agglomeration phenomenon is many, it is evaluated as 1 point;

[0121] The score ranges from 1 to 5 according to the dispersion situation;

[0122] Stability test:

[0123] The sample is placed at room temperature for 10 days to observe whether there is precipitation in the conductive ink paste (it is observed that all inks have precipitation); the evaluation index is: the looseness of the paste, and whether it can be in a dispersed state when the liquid is slightly shaken; the stability is scored according to the dispersion state, from 1 to 5 points. The higher the score, the better the looseness and the better the dispersion state;

[0124] Electrical performance test:

[0125] According to the method specified in IEC61189-3, use a digital multimeter to measure the diagonal resistance of 1 cm 2 area of the above-mentioned conductive ink film layer, and measure three times and take the average value to obtain the resistance value R s of this film layer (film thickness 15 mm); s (15 mm);

[0126] At the same time, measure the resistance (R s (15 mm): 120 - 200 Ω) of other commercially available carbon-based conductive inks and the resistance value (R s (15 mm): 40 - 90 Ω) of commercially available nano-silver paste conductive ink.

[0127] Mechanical property test:

[0128] The test results are shown in Table 1 below;

[0129] Table 1 Test result table

[0130]

[0131]

[0132] Result analysis:

[0133] 1. It can be seen from Examples 1 to 4 that by using the method based on electric field and electrostatic assembly, a composite material meeting the requirements of conductive ink can be prepared. The conductive ink prepared from this composite material has good dispersibility and stability and good conductivity; the reason for this result is that the specifications of the nickel powder are appropriate. If the particle size of the nickel powder is too small, there is no suitable graphene powder for good coating. If the particle size of the nickel powder is too large, it will lead to a decrease in its dispersibility and stability in the ink;

[0134] 2. As can be seen from Examples 5 to 8, as the particle size of nickel powder increases, the stability and conductivity of the conductive ink decrease; as the particle size of nickel powder decreases, the stability of the conductive ink increases to some extent, but the conductivity is worse. This shows that the performance of the conductive ink is related to two factors: 1. Dispersibility and stability. The good and persistent dispersion of the composite material is an effective guarantee for maintaining the uniform dispersion of the composite material in the ink coating, which directly affects the conductivity; 2. Coating performance. As described above, when the particle size of nickel powder is too small, it is difficult to prepare graphene with a sheet diameter below 100 nm, and it is difficult to coat nickel powder with a diameter of 20 to 30 μm well with graphene with a sheet diameter above 100 nm, resulting in poor coating performance and ultimately poor conductivity despite good dispersibility.

[0135] 3. As can be seen from Example 9, the tissue effect of the secondary flow channel is better than that of the main flow channel;

[0136] In the present invention, the main flow channel is mainly used for liquid mixing with the secondary flow channel and improving the liquid mixing degree in the channel, improving the mixing uniformity between particles, and improving the electrostatic assembly effect based on the electric field; if the assembly position is placed in the main flow channel, the flow rate is too fast, the particle coating stability is affected, and the conductivity is affected;

[0137] 4. As can be seen from Example 10, the method of wet reduction is better than the method of dry reduction; we believe that the method of dry reduction has a certain surface destructiveness to ions, resulting in the above gap.

[0138] 5. As can be seen from Comparative Example 1, electrostatic assembly based on the electric field is necessary. After losing the electric field, the assembly uniformity may be affected. As can be seen from Comparative Example 2, using imidazole with unsaturated bonds can improve the affinity between particles and resin, and improve the stability and conductivity.

Claims

1. A preparation method of a surface-modified IRGO@Ni highly conductive ink material, characterized in that, It includes the following steps: Step 1: Under the action of an electric field, a composite material GO@Ni of graphene oxide-coated nickel powder is prepared using graphene oxide and spherical nickel powder as raw materials. Step 2: The composite material GO@Ni is reduced to obtain a composite material RGO@Ni of graphene-coated nickel powder.

2. The preparation method according to claim 1, characterized in that It further includes Step 3: A grafting group with unsaturated double bonds is loaded on the surface of the composite material RGO@Ni to obtain a composite material IRGO@Ni.

3. The preparation method according to claim 1, characterized in that, The sheet width of the graphene oxide is 100 - 200 nm; the diameter of the spherical nickel powder is 40 - 75 μm.

4. The preparation method according to claim 1, characterized in that, The specific operation of Step 1 is as follows: Step 11: An electroplating solution containing graphene oxide, spherical nickel powder, and a conductive agent is added to an electrolytic cell; a voltage of 3.5 - 4.5 V, a current of 15 - 35 A, and an electroplating time of 30 - 60 min are applied to the electrodes in the electrolytic cell. Step 12: The deposit obtained after the treatment in Step 11 is collected, washed, and dried to obtain the composite material GO@Ni. The electroplating solution contains 0.1 - 0.5 mg / mL of graphene oxide, 2 - 4 mg / mL of spherical nickel powder, and 1 - 2 mg / mL of a conductive agent. The conductive agent is a soluble metal salt, and the cation of the soluble metal salt is not reduced under the electric field.

5. The preparation method according to claim 1, characterized in that, The reduction method in Step 2 is wet reduction or dry reduction. The method of wet reduction is: Using sodium borohydride as a reducing agent, the composite material GO@Ni is reductively treated in an alkaline solution to obtain the composite material RGO@Ni. The method of dry reduction is: Sintering is carried out in a reducing atmosphere to obtain the composite material RGO@Ni.

6. The preparation method according to claim 2, characterized in that, The specific operation of Step 3 is: The composite material RGO@Ni is added to vinylimidazole ionic liquid for reaction so that the vinylimidazole ionic liquid can be loaded on the surface of the composite material RGO@Ni to obtain the composite material IRGO@Ni.

7. A composite material IRGO@Ni, characterized in that, It is prepared by using the method according to any one of claims 1 to 6.

8. A conductive ink, characterized in that, It includes the composite material IRGO@Ni according to claim 7, a resin for ink, a dispersant, and a solvent; the dosage of the composite material IRGO@Ni is 30 - 45 wt%.

9. The electrically conductive ink according to claim 8, wherein, The weight ratio of the resin, dispersant, and solvent is 40 - 85:5 - 13:

100.

10. The electrically conductive ink according to claim 9, wherein, The resin is a photosensitive resin, a vinyl chloride - vinyl acetate copolymer resin, an acrylic resin, a polyester resin, a polyimide resin, or a mixture of one or more of them in any proportion. The dispersant is polyethylene glycol, methyl cellulose, ethyl cellulose, and polyvinylpyrrolidone (PVP), or a combination of several of them. The solvent is water, ethanol, acetone, N,N - dimethylformamide, NMP, ethyl acetate, and a diester, or a mixture of several of them.

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