Graphene water-based ink with high solid content as well as preparation method and application of graphene water-based ink

Abstract

The invention discloses high-solid-content graphene water-based ink as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing graphene slurry, a grinding medium, a dispersing agent and graphene powder, and sanding under a heat preservation condition to prepare the graphene water-based ink with high solid content. The high-solid-content graphene water-based ink disclosed by the invention can be used for preparing a graphene RFID (Radio Frequency Identification Device) antenna through silk-screen printing, and the printed antenna is clear in pattern, free from water stain and free from obvious blooming at the edge; and the graphene RFID antenna can be prepared from the ink through one-time printing, so that the difficulty of a printing process is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a graphene aqueous ink with a high solid content, its preparation method and application, and belongs to the technical field of graphene inks. Background Art

[0002] Graphene aqueous ink is a new type of ink that combines the material characteristics of graphene and the environmental protection characteristics of aqueous ink. Graphene aqueous ink uses water as a solvent and has the advantages of environmental protection, safety, non-toxicity, non-flammability, non-explosion, and no volatile organic gases. Graphene aqueous ink also has good electrical conductivity and can be widely used in printing high-performance flexible circuit boards, resistive heaters, RFID tags, etc. In industrial production, in order to achieve better printing effects, the properties such as the solid content, viscosity, and fluidity of graphene aqueous ink are often adjusted according to the actual product requirements. The graphene aqueous ink prepared in the patent with the publication number CN117613537A has a solid content of 9% and a viscosity of 2000 - 4000 mPa·s. The solid content is relatively low and the viscosity is relatively high. When this ink is directly screen-printed to prepare RFID antennas and RFID tags, there are the following problems: the printed pattern outline is not clear, the water stains are serious, there are traces of bleeding, the mesh holes of the printed pattern are relatively large, and the holes are obvious; at the same time, this ink requires secondary printing, and the secondary printing alignment is difficult, with a very high precision requirement for the process, which greatly affects the production efficiency. Summary of the Invention

[0003] The main purpose of the present invention is to provide a graphene aqueous ink with a high solid content, its preparation method and application, so as to overcome the deficiencies in the prior art.

[0004] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include: An embodiment of the present invention provides a preparation method of a graphene aqueous ink with a high solid content, which includes: Mixing graphene slurry, grinding medium, dispersant, and graphene powder and performing sanding treatment under heat preservation conditions to obtain a graphene aqueous ink with a high solid content.

[0005] An embodiment of the present invention also provides a graphene aqueous ink with a high solid content for screen printing prepared by the foregoing preparation method, and the solid content of the graphene aqueous ink is 12 - 20 wt%.

[0006] An embodiment of the present invention also provides a graphene RFID antenna, which is prepared by one-time screen printing and roll pressing using the foregoing graphene aqueous ink with a high solid content.

[0007] An embodiment of the present invention also provides a graphene RFID tag, which includes the foregoing graphene aqueous ink with a high solid content.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a graphene aqueous ink with a high solid content, which can be used for screen printing to prepare graphene RFID antennas. The printed antenna patterns are clear, without water stains, and there is no obvious bleeding at the edges. (2) In the prior art, the preparation of tags involves secondary printing + roll pressing. Secondary printing requires the alignment of tags, which has high requirements for accuracy and operation, and the production efficiency is very slow. However, the ink in the present application can be used to prepare graphene RFID antennas through one-time printing, reducing the difficulty of the printing process and improving the production efficiency. Detailed implementation manners

[0009] In view of the deficiencies of the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. To facilitate the understanding of this application, the following will describe this application in more detail. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the implementation manners or embodiments described herein. On the contrary, the purpose of providing these implementation manners or embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0010] Specifically, as an aspect of the technical solution of the present invention, a preparation method of a graphene aqueous ink with a high solid content includes: Mix graphene slurry, grinding medium, dispersant, and graphene powder and perform sanding treatment under heat preservation conditions to obtain a graphene aqueous ink with a high solid content.

[0011] The heat preservation in the present invention can be understood as air heat preservation. In the prior art, when preparing graphene ink, condensed water needs to be introduced into the jacket of the sanding device to rapidly cool the inside of the sanding device. In contrast to the prior art, the present invention does not require the introduction of condensed water into the jacket of the sanding device. At this time, the jacket plays a role of heat preservation. For example, currently, a jacketed double-layer tank is used for condensation reflux, and flowing water is passed through. When this double-layer tank is used in the present invention, flowing water is not passed through, and the inside is air, which can be understood as air heat preservation.

[0012] In some embodiments, the preparation method specifically includes: mixing graphene slurry and grinding medium in a sanding device, then sequentially adding a dispersant and graphene powder for sanding treatment, and simultaneously maintaining the material under heat preservation conditions to remove the water vapor generated during the sanding treatment.

[0013] Furthermore, to remove the water vapor generated during the sanding treatment, the lid of the sanding device can be opened, holes can be drilled in the lid, and external equipment can be connected to extract the water vapor, etc. In addition, during the process of removing the water vapor, attention needs to be paid to heat preservation to prevent the heat from dissipating too quickly.

[0014] Furthermore, the cover of the feeding port of the sand mill can be partially opened, so that water vapor can be removed while preventing heat from dissipating too quickly. For example, the cover of the feeding port can be opened by 30%.

[0015] In some embodiments, the preparation method specifically comprises: The graphene slurry and the grinding medium are mixed in a sand mill, and then a dispersant and graphene powder are added in sequence, and the mixture is sand milled at a rotation speed of 3000-3500 r / min for 3-7 hours to obtain a mixed slurry; And, the mixed slurry is sieved to obtain the graphene water-based ink.

[0016] Furthermore, the sieving process is performed while hot. Here, "while hot" means sieving immediately or after a while after sanding, but before it is completely cooled.

[0017] Furthermore, the screening process is a graded screening process.

[0018] The graphene slurry and grinding media of the present invention generate a large amount of heat during the sand milling process, and because the sand milling is carried out in a heat-insulating environment, the heat is not easy to dissipate. The heat can promote the evaporation of water in the graphene slurry during the sand milling process, effectively remove excess water, increase the solid content and viscosity of the graphene water-based ink, and shorten the sedimentation time; the graphene powder and the graphene slurry are blended to further increase the solid content and viscosity of the graphene water-based ink; the sieving treatment is carried out while hot because the graphene water-based ink is better dispersed at this time, which can improve the dispersion efficiency. In addition, if the graphene water-based ink is cooled and then sieved, the ink will wrap the grinding medium and lose part of the ink; the graded sieving is adopted because the grinding medium can be removed first to prevent the grinding medium from clogging the mesh of the secondary screen, which can greatly improve the sedimentation efficiency and reduce the sedimentation time.

[0019] Furthermore, the dispersant is added in small amounts and multiple times, with the amount added each time being 5%-10% of the total amount of the dispersant.

[0020] Furthermore, the graphene powder is added in small amounts and multiple times, and the amount added each time is 1%-5% of the total amount of graphene powder.

[0021] The dispersant is added to enhance the dispersion stability of graphene powder in the slurry, and at the same time, in the subsequent printing of the antenna, the adhesion between the graphene water-based ink and the base material can be enhanced. The dispersant and graphene powder are added in small amounts and multiple times to make the two more evenly distributed in the graphene slurry and prevent a large amount of dust from being ejected.

[0022] Further, the classification and sieving treatment specifically includes: subjecting the mixed slurry to primary sieving treatment using a 40-60 mesh sieve, and then subjecting it to secondary sieving treatment using a 1000-1500 mesh sieve to obtain the graphene aqueous ink.

[0023] Further, the concentration of the graphene slurry is 4wt% - 6wt%. Since graphene has a lamellar structure, currently, industrial graphene with 3 - 8 layers is relatively good. If the slurry concentration is too high, the graphene lamellae will stack, affecting the effect. Therefore, currently, the concentration of the graphene slurry is usually 4wt% - 6wt%.

[0024] Further, the number of layers of graphene in the graphene slurry is 3 - 8 layers.

[0025] Further, the grinding medium includes any one or a combination of zirconium beads, cast iron balls, and agate balls, and is not limited thereto.

[0026] Further, the graphene powder used in the present invention is the same as the graphene in the graphene slurry.

[0027] Further, the dispersant includes any one or a combination of PVP, sodium dodecyl sulfate, and polyacrylamide, and is not limited thereto.

[0028] Further, the mass ratio of the grinding medium to the graphene slurry is (1 - 1.5):1.

[0029] Further, the dosage of the dispersant is 0.5wt% - 1.5wt% of the graphene slurry.

[0030] Further, the dosage of the graphene powder is 4wt% - 15wt% of the graphene slurry.

[0031] In some more specific embodiments, the method for preparing the high-solid-content graphene aqueous ink for screen printing includes: Take 10 kg of 6wt% graphene slurry and mix it evenly with 13 kg of zirconium beads. Add 100 g of PVP powder and 400 g of graphene powder. Add them to the mixed slurry in sequence and in small amounts multiple times (first add 5 g of PVP powder at a time until 100 g is reached, and then add 5 g of graphene powder at a time until 400 g is filled). Under the insulation state, perform sand grinding at 3000 - 3500 r / min for 3 - 5 h. When sand grinding, open the lid of the sand grinding device partially to let the water vapor generated by self-heating volatilize. When the sand grinding time is reached, immediately filter through a 60-mesh sieve while it is hot to remove the zirconium beads, and then filter the graphene aqueous ink through a 1000-mesh sieve to remove a part of the water, and the high-solid-content graphene aqueous ink can be obtained.

[0032] The present invention utilizes the heat generated by the grinding and cutting of zirconium beads and graphene sheets to concentrate the graphene slurry. The heat generated in this part can effectively remove the water molecules in the graphene aqueous ink and reduce the agglomeration of graphene sheets. The graphene powder and the graphene slurry are blended, and a PVP dispersant is added at the same time, which can effectively increase the solid content and viscosity of the graphene aqueous ink. After classification and sieving, a 60-mesh sieve is used to remove part of the zirconium beads. Then, according to the particle size of the aqueous ink, a sieve with a high mesh number is selected to remove part of the water in the ink to increase the solid content of the ink.

[0033] As another aspect of the technical solution of the present invention, it relates to a graphene aqueous ink with a high solid content for screen printing prepared by the aforementioned preparation method, and the solid content of the graphene aqueous ink is 12-20 wt%.

[0034] As another aspect of the technical solution of the present invention, it also relates to the use of the aforementioned graphene aqueous ink with a high solid content for screen printing in the preparation of graphene RFID antennas or graphene RFID tags.

[0035] As another aspect of the technical solution of the present invention, it also relates to a graphene RFID antenna, and the graphene RFID antenna is prepared by one-time screen printing and roll pressing using the aforementioned graphene aqueous ink with a high solid content.

[0036] In some embodiments, the sheet resistance of the graphene RFID antenna is 5-20 Ω / square.

[0037] In some embodiments, the thickness of the graphene RFID antenna is 10-70 μm.

[0038] As another aspect of the technical solution of the present invention, it also relates to a graphene RFID tag, which includes the aforementioned graphene aqueous ink with a high solid content.

[0039] In the prior art, in the two-step printing + roll pressing process for preparing RFID antennas, when the first printing is carried out, the graphene ink is applied to the PET substrate, resulting in a thin antenna thickness and a large sheet resistance, and the performance is poor at this time, unable to meet the usage requirements. Therefore, a second printing is carried out, that is, the graphene ink is overprinted on the graphene substrate obtained from the first printing. At this time, the binding force between graphene and graphene is stronger than the binding force between graphene and PET. After the second printing, the thickness of the obtained graphene antenna is thicker and the sheet resistance is smaller than that after the first printing. Further roll pressing is carried out to obtain a graphene antenna with a lower sheet resistance, and finally the prepared tag meets the actual application.

[0040] In some embodiments, the graphene RFID tag uses a metal conductive material as the chip flip-chip interface.

[0041] Since the graphene aqueous ink of the present invention has a high solid content and high viscosity, when screen printing, an antenna with a relatively thick thickness and low sheet resistance can be obtained after one printing. After further roll pressing, the graphene sheets are compact and the sheet resistance is low, and thus an antenna and a tag that meet the actual application can be obtained.

[0042] The present invention is further illustrated by the following examples: According to the following examples, the present invention can be better understood. However, those skilled in the art can easily understand that the specific material ratios, process conditions and their results described in the examples are only used to illustrate the present invention and should not and will not limit the present invention described in detail in the claims.

[0043] Unless otherwise specified, all raw materials, reaction equipment, test equipment and test methods used in the following examples are well-known in the art.

[0044] Example 1 Take 10 kg of 6 wt% graphene slurry and mix it evenly with 13 kg of zirconium beads, then add 100 g of PVP powder and 400 g of graphene powder in sequence and in small amounts multiple times. Among them, the PVP powder is added at 5 g / time until 100 g, and the graphene powder is added at 5 g / time until 400 g. Under the condition of heat preservation, sand milling is carried out at 3500 r / min for 3 h. During sand milling, the lid of the sand milling device is partially opened to remove the water vapor generated by self-heating. After sand milling, a mixed slurry is obtained. While it is hot, the mixed slurry is filtered through a 60-mesh sieve to remove the zirconium beads, and then filtered through a 1000-mesh sieve. After the two-stage sieved mixed slurry is settled for 1 day to remove part of the water, graphene aqueous ink can be obtained. Through the solid content test, the solid content of this graphene aqueous ink is 15 wt%.

[0045] Take 10 g of the above graphene aqueous ink in a petri dish, spread it out and dry it, and the sheet resistance of the ink layer is measured to be between 300 - 500 mΩ / □.

[0046] Screen printing is carried out with 15 wt% high-solid-content graphene aqueous ink. The antenna pattern obtained by one printing is clear, without obvious water stains, and the mesh holes are small. Among them, the thickness of the antenna pattern is 42 μm, and the sheet resistance is 20 - 22 Ω / □. After roll pressing, the thickness of the antenna pattern is 15 μm, and the sheet resistance is 10 - 11 Ω / □.

[0047] The reading distance of the graphene RFID tag prepared from this antenna is 8.2 m. The reading distance of the graphene RFID tag is improved, and the process difficulty is also reduced.

[0048] Example 2 Compared with Example 1, the amounts of zirconium beads, dispersant and graphene powder are different; Mix 10 kg of 6 wt% graphene slurry and 15 kg of zirconium beads evenly, then add 150 g of PVP powder and 1 kg of graphene powder in turn and in small amounts multiple times. Among them, the PVP powder is added in increments of 10 g each time until 150 g is reached, and the graphene powder is added in increments of 15 g each time until 1 kg is reached. Under the condition of heat preservation, grind with a sand mill at 3500 r / min for 5 h. During sanding, the lid of the sanding device is partially opened to remove the water vapor generated by self-heating. After sanding, a mixed slurry is obtained. While it is still hot, filter the mixed slurry through a 40-mesh sieve. After removing the zirconium beads, filter it through a 1000-mesh sieve. Let the mixed slurry after two-stage sieving settle for 1 day to remove some water, and then graphene aqueous ink can be obtained. Through solid content testing, the solid content of this graphene aqueous ink is 17 wt%.

[0049] Take 10 g of the above-mentioned graphene aqueous ink in a petri dish, spread it out and dry it, and the surface resistance of the ink layer is measured to be between 300 - 500 mΩ / □.

[0050] Use the graphene aqueous ink with a high solid content of 17 wt% for screen printing. The antenna pattern obtained by one-time printing is clear, without obvious water stains, and the mesh holes are small. Among them, the thickness of the antenna pattern is 43 μm, the surface resistance is 18 - 19 Ω / □, and the thickness of the antenna pattern after rolling is 16 μm, and the surface resistance is 8 - 9 Ω / □.

[0051] The reading distance of the graphene RFID tag prepared from this antenna is 8.5 m. The reading distance of the graphene RFID tag is increased, and the process difficulty is also reduced.

[0052] Example 3 Compared with Example 1, the dosages of zirconium beads, dispersant and graphene powder are different; Mix 10 kg of 6 wt% graphene slurry and 15 kg of zirconium beads evenly, then add 150 g of PVP powder and 1.5 kg of graphene powder in turn and in small amounts multiple times. Among them, the PVP powder is added in increments of 15 g each time until 150 g is reached, and the graphene powder is added in increments of 15 g each time until 1.5 kg is reached. Under the condition of heat preservation, grind with a sand mill at 3500 r / min for 7 h. During sanding, the lid of the sanding device is partially opened to remove the water vapor generated by self-heating. After sanding, a mixed slurry is obtained. While it is still hot, filter the mixed slurry through a 40-mesh sieve. After removing the zirconium beads, filter it through a 1500-mesh sieve. Let the mixed slurry after two-stage sieving settle for 1 day to remove some water, and then graphene aqueous ink can be obtained. Through solid content testing, the solid content of this graphene aqueous ink is 20 wt%.

[0053] Take 10 g of the above-mentioned graphene aqueous ink in a petri dish, spread it out and dry it, and the surface resistance of the ink layer is measured to be 300 - 500 mΩ / □.

[0054] Screen printing was carried out using graphene aqueous ink with a high solid content of 20 wt%. The antenna pattern obtained by one-time printing was clear, without obvious water stains, and the mesh holes were small. The thickness of the antenna pattern was 45 μm, the sheet resistance was 15 - 17 Ω / □. After roll pressing, the thickness of the antenna pattern was 17 μm, and the sheet resistance was 5 - 6 Ω / □.

[0055] The reading distance of the graphene RFID tag prepared from this antenna was 9 m. The reading distance of the graphene RFID tag was improved, and the process difficulty was also reduced.

[0056] Example 4 Compared with Example 1, it was not sieved while it was hot. 10 kg of 6 wt% graphene slurry was mixed evenly with 13 kg of zirconium beads, and then 100 g of PVP powder and 400 g of graphene powder were added. They were added in small amounts and multiple times in turn. Among them, the PVP powder was added at 5 g / time until 100 g, and the graphene powder was added at 5 g / time until 400 g. Under the condition of heat preservation, it was sanded for 3 h at 3500 r / min. During sanding, the lid of the sanding device was partially opened to remove the water vapor generated by self-heating. After sanding, a mixed slurry was obtained. After standing for 30 min and cooling, it was found that a large amount of viscous graphene ink agglomerated on the zirconium beads. It was difficult to filter using a 60-mesh sieve, and a large amount of graphene ink was lost after filtration. After removing the zirconium beads, it was filtered through a 1500-mesh sieve again. After the mixed slurry passed through two-stage sieving and settled for 1 day, part of the water was removed, and then graphene aqueous ink could be obtained. Through the solid content test, the solid content of this graphene aqueous ink was 12 wt%.

[0057] 10 g of the above graphene aqueous ink was taken in a petri dish and dried flat. The sheet resistance of the ink layer was measured to be 300 - 500 mΩ / □. Therefore, the performance of the graphene aqueous ink was not affected by filtering after cooling.

[0058] Screen printing was carried out using graphene aqueous ink with a high solid content of 12 wt%. The antenna pattern obtained by one-time printing was clear, without obvious water stains, and the mesh holes were small. The thickness of the antenna pattern was 40 μm, the sheet resistance was 25 - 27 Ω / □. After roll pressing, the thickness of the antenna pattern was 15 μm, and the sheet resistance was 12 - 13 Ω / □.

[0059] The reading distance of the graphene RFID tag prepared from this antenna was 8.7 m. The reading distance of the graphene RFID tag was improved, and the process difficulty was also reduced.

[0060] Comparative Example 1: Grinding under condensation conditions Mix 500 g of 6 wt% graphene slurry and 650 g of zirconium beads evenly, then add 5 g of PVP powder and 20 g of graphene powder in turn and in small amounts multiple times. Among them, the PVP powder is added at 1 g / time until 5 g, and the graphene powder is added at 4 g / time until 20 g. Under the condensation state, grind with a sand mill at 3500 r / min for 3 h, and then use a 60-mesh sieve to remove the zirconium beads to obtain graphene water-based ink. After the solid content test, the solid content of this graphene water-based ink is 9.5 wt%. This graphene water-based ink is not suitable for single printing and requires double printing. After natural sedimentation for 1 day, perform a 1000-mesh sieving, remove the supernatant, and then graphene water-based ink can be obtained. After the solid content test, the solid content of this graphene water-based ink is 10 wt%, but the viscosity is still not enough and it is still not suitable for single printing and requires double printing.

[0061] In summary, when preparing graphene water-based ink under the condensation state, only a solid content of 10 wt% can be obtained under the same sedimentation time, which is much lower than the 15 wt% solid content obtained under the heat preservation state in Example 1. If you want to obtain graphene water-based ink with the same solid content, a longer sedimentation time is required.

[0062] Take 10 g of the above graphene water-based ink with a solid content of 10 wt% in a petri dish. After spreading and drying, the ink layer is relatively flat, with only a little agglomeration, and the measured sheet resistance is 300 - 500 mΩ / □.

[0063] Comparative Example 2: Heat the graphene water-based ink after condensation reflux Mix 1 kg of 6 wt% graphene slurry and 1.3 kg of zirconium beads, grind with a sand mill at 3500 r / min for 3 h under the condensation reflux state. First, use a 60-mesh sieve to remove the zirconium beads, and then filter through a 1000-mesh sieve. After natural sedimentation to remove the supernatant of the mixed slurry after two-stage sieving, graphene water-based ink can be obtained. After the solid content test, the solid content of this graphene water-based ink is 6.5 wt%. Then heat the graphene water-based ink with a solid content of 6.5 wt% at 100 °C for 1 h to obtain graphene water-based ink with a solid content of 15%.

[0064] Take 10 g of the above graphene water-based ink with a solid content of 6.5 wt% in a petri dish. After spreading and drying, the measured sheet resistance of the ink layer is 300 - 500 mΩ / □.

[0065] Take 10 g of the above graphene water-based ink with a solid content of 15 wt% in a petri dish. After spreading and drying, the measured sheet resistance of the ink layer rises to 1 - 1.5 Ω / □. And during the printing process, the sheet resistance of the antenna is uneven, and the difference in sheet resistance at different points is large.

[0066] Comparative Example 3: Grind directly under heat preservation conditions without adding dispersant and graphene powder Take 1 kg of 6 wt% graphene slurry and blend it with 1.3 kg of zirconium beads. Under the condition of heat preservation and at 3500 r / min, sand the graphene slurry for 3 h. First, use a 60-mesh filter to remove the zirconium beads, and then settle for 1 day to remove the supernatant. Then the graphene aqueous ink can be obtained. Through the solid content test, the solid content of this graphene aqueous ink is 7.5 wt%. The prepared graphene aqueous ink is dilute and is not suitable for single printing, but requires double printing.

[0067] Take 10 g of the above-mentioned graphene aqueous ink with a solid content of 7.5 wt% in a petri dish. After spreading and drying, the surface resistance of the ink layer is measured to be 400 - 500 mΩ / □.

[0068] Comparative Example 4: Directly disperse and add graphene powder (not sanded), without adding a dispersant Take 500 ml of the graphene aqueous ink with a solid content of 7.5 wt% in Comparative Example 3 and 12.5 g of graphene powder. The graphene powder is added to the mixed slurry at 2.5 g per time until it is completely added. Finally, disperse and process it for 30 min under the condition of a rotation speed of 1000 r / min to obtain the graphene aqueous ink. Through the solid content test, the solid content of this graphene aqueous ink is 10 wt%. This graphene aqueous ink has obvious particle sense and is still not suitable for screen printing.

[0069] Take 10 g of the above-mentioned graphene aqueous ink with a solid content of 10 wt% in a petri dish. After spreading and drying, there is obvious surface agglomeration in the ink layer, and the measured surface resistance is 500 mΩ - 1000 mΩ / □.

[0070] Comparative Example 5: Add metal compound powder Take 500 ml of the graphene aqueous ink with a solid content of 7.5 wt% in Comparative Example 3 and mix it with 12.5 g of titanium boride metal compound powder, and disperse and process it for 30 min under the condition of a rotation speed of 1000 r / min to obtain the graphene-metal compound mixed ink. This ink has obvious particle sense and is unevenly dispersed.

[0071] Take 10 g of the above-mentioned graphene-metal compound mixed aqueous ink in a petri dish. After spreading and drying, it is measured that the surface resistance of the ink layer not only does not decrease, but instead increases to 1 - 1.2 Ω / □, with poor conductivity and is not suitable for screen printing.

[0072] Comparative Example 6: Add too much dispersant under the condition of heat preservation Take 3kg of 6wt% graphene slurry and 3.9kg of zirconium beads and mix them evenly, then add 90g of PVP powder and 120g of graphene powder, sequentially and in small amounts multiple times, wherein PVP powder is added to 90g at 10g / time, and graphene powder is added to 120g at 5g / time. Sand grind at 3500r / min for 3h under insulation state, and then use 60 mesh filtration to remove zirconium beads. After natural sedimentation for 1 day, sieve through 1000 mesh to remove a certain amount of water to obtain a graphene water-based ink with good dispersion. The solid content test shows that the solid content of the graphene water-based ink is 12.4wt%.

[0073] 10g of the above graphene water-based ink with a solid content of 12.4wt% was taken into a surface dish, and the ink layer was relatively flat after being spread and dried. The measured sheet resistance of the ink layer was 900mΩ / □-1 Ω / □. That is, although too much dispersant can improve the dispersibility of graphene, it increases the sheet resistance of the ink, resulting in reduced conductivity.

[0074] Comparative Example 7 Screen printing was performed using a graphene water-based ink with a solid content of 9wt% prepared by the method in the patent with publication number CN117613537A. The antenna pattern obtained by the first printing had serious water stains, unclear outlines, and traces of smudging. The thickness of the antenna formed by the ink was 5μm, and the square resistance was 30-40 Ω / □. By observing the edge of the antenna pattern through a polarizing microscope, the smudging of the ink can be more clearly and intuitively found. Under the irradiation of a daily lamp, it can be found that the mesh of the antenna pattern is large, and the performance of the graphene RFID tag prepared with the antenna is poor, and the reading distance is only 3m. Therefore, in practical applications, after the first printing, a second printing will be performed in alignment. The thickness of the antenna formed by the ink is 15μm, and the square resistance can reach 14-16Ω / □. Then, the rolling process is performed, and the thickness of the antenna is 9 μm, and the square resistance of the antenna can reach 7-8 Ω / □. The reading distance of the graphene RFID tag prepared by the antenna is 7m. The reading distance and performance of this graphene RFID tag can meet the actual application requirements, but it needs to be printed a second time. The second printing is difficult to align and requires high process precision, which greatly affects production efficiency.

[0075] Comparative Example 8 Compared with Example 1, carbon black powder is used instead of graphene powder; Take 3 kg of 6 wt% graphene slurry and mix it evenly with 3.9 kg of zirconium beads. Then add 30 g of PVP powder and 300 g of carbon black powder in sequence and in small amounts multiple times. Among them, the PVP powder is added in increments of 5 g each time until 30 g is reached, and the carbon black powder is added in increments of 10 g each time until 300 g is reached. Under the condition of heat preservation, grind it with a sand mill at 3500 r / min for 3 h. Then use a 60-mesh sieve to remove the zirconium beads. After natural sedimentation for 1 day, sieve it through a 1000-mesh sieve to remove a certain amount of moisture, and then graphene / carbon black composite water-based ink can be obtained. Through the solid content test, the solid content of this graphene / carbon black composite water-based ink is 15 wt%.

[0076] Take 10 g of the above-mentioned graphene / carbon black composite water-based ink in a petri dish. After spreading it out and drying, the ink layer splits severely and the film-forming property is poor. The surface resistance of the ink layer measured is 1.5 - 2.0 Ω / □. That is, the addition of carbon black affects the film-forming property of the graphene / carbon black composite water-based ink.

[0077] Comparative Example 9 Compared with Example 1, replace the graphene powder with carbon nanotube powder; Take 3 kg of 6 wt% graphene slurry and mix it evenly with 3.9 kg of zirconium beads. Then add 30 g of PVP powder and 300 g of carbon nanotube powder in sequence and in small amounts multiple times. Among them, the PVP powder is added in increments of 5 g each time until 30 g is reached, and the carbon nanotube powder is added in increments of 10 g each time until 300 g is reached. Under the condition of heat preservation, grind it with a sand mill at 3500 r / min for 3 h. Then use a 60-mesh sieve to remove the zirconium beads. After natural sedimentation for 1 day, sieve it through a 1000-mesh sieve to remove a certain amount of moisture, and then graphene / carbon nanotube composite water-based ink can be obtained. Through the solid content test, the solid content of this graphene / carbon nanotube composite water-based ink is 14.3 wt%.

[0078] Take 10 g of the above-mentioned graphene / carbon nanotube composite water-based ink in a petri dish. After spreading it out and drying, the ink layer splits severely and the film-forming property is poor. The surface resistance of the ink layer measured is 0.4 - 1.5 Ω / □. That is, the addition of carbon nanotubes affects the film-forming property of the graphene / carbon nanotube composite water-based ink.

[0079] In addition, the inventor of this case also referred to the foregoing embodiments and conducted tests with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0080] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A preparation method of graphene aqueous ink with high solid content, characterized in that, Comprising: Mix graphene slurry, grinding medium, dispersant, and graphene powder and perform sand grinding treatment under heat preservation conditions to obtain graphene aqueous ink with a high solid content.

2. The preparation method according to claim 1, wherein Specifically comprising: Mix graphene slurry and grinding medium in a sand grinding device, then sequentially add dispersant and graphene powder for sand grinding treatment, while maintaining the material under heat preservation conditions to remove the water vapor generated during the sand grinding treatment.

3. The preparation method according to claim 2, characterized in that, Specifically comprising: Mix graphene slurry and grinding medium in a sand grinding device, then sequentially add dispersant and graphene powder and perform sand grinding treatment for 3 - 7 h under the condition of a rotational speed of 3000 - 3500 r / min to obtain a mixed slurry; And, perform sieving treatment on the mixed slurry to obtain the graphene aqueous ink.

4. The preparation method according to claim 3, characterized in that, Specifically comprising: The sieving treatment is carried out while it is hot; And / or, the sieving treatment is a grading sieving treatment.

5. The preparation method according to claim 4, characterized in that: The dispersant is added in a small - amount - multiple - times manner, and the addition amount each time is 5% - 10% of the total amount of the dispersant; And / or, the graphene powder is added in a small - amount - multiple - times manner, and the addition amount each time is 1% - 5% of the total amount of the graphene powder; And / or, the grading sieving treatment specifically comprises: perform primary sieving treatment on the mixed slurry using a 40 - 60 - mesh sieve, and then perform secondary sieving treatment using a 1000 - 1500 - mesh sieve to obtain the graphene aqueous ink.

6. The preparation method according to claim 3, characterized in that: The concentration of the graphene slurry is 4 - 6 wt%; and / or, the number of layers of graphene in the graphene slurry is 3 - 8 layers; And / or, the dispersant comprises any one or a combination of multiple of PVP, sodium dodecyl sulfate, and polyacrylamide; And / or, the mass ratio of the grinding medium to the graphene slurry is (1 - 1.5):1; And / or, the dosage of the dispersant is 0.5 wt% - 1.5 wt% of the graphene slurry; And / or, the dosage of the graphene powder is 4 wt% - 15 wt% of the graphene slurry.

7. The graphene aqueous ink with high solid content prepared by the preparation method according to any one of claims 1-6, characterized in that: The solid content of the graphene aqueous ink is 12 - 20 wt%.

8. A graphene RFID antenna, characterized in that: The graphene RFID antenna is prepared by one - time screen printing and rolling treatment using the high - solid - content graphene aqueous ink described in claim 7.

9. The graphene RFID antenna according to claim 8, wherein: The sheet resistance of the graphene RFID antenna is 5 - 20 Ω / sq; and / or, the thickness of the graphene RFID antenna is 10 - 70 μm.

10. A graphene RFID tag, characterized in that Comprising the high - solid - content graphene aqueous ink described in claim 7.