RFID composite conductive paste and preparation method therefor, and RFID electronic tag

Abstract

The present invention belongs to the technical fields of electronic materials and electronic devices, and provides an RFID composite conductive paste and a preparation method therefor, and an RFID electronic tag. The RFID composite conductive paste comprises the following components in parts by weight: 10-25 parts of an oily special crosslinked resin, 30-50 parts of a metal conductive agent, 5-10 parts of a two-dimensional carbon-based material, 20-50 parts of an organic solvent, 10-20 parts of a quick-drying agent, and 2-5 parts of a leveling agent. The RFID composite conductive paste provided by the present invention has high solid content conductive components, ideal dispersity and uniformity, and balanced and stable properties.

Description

RFID composite conductive paste and preparation method thereof, RFID electronic tag Technical Field

[0001] The present invention belongs to the technical field of electronic materials and electronic equipment, and particularly relates to new materials and new processes for preparing electronic components and the electronic components prepared therefrom. Specifically, a RFID composite conductive paste and a preparation method thereof and an RFID electronic tag are provided. Background Art

[0002] RFID, also known as radio frequency identification, is a type of automatic identification technology, originally derived from radar technology. It utilizes radio frequency for contactless, two-way communication, using electronic tags or radio frequency cards for reading and writing. Its advantage lies in its high-speed and accurate contactless identification. As the technological foundation of the Internet of Things, related industries and technologies are developing rapidly.

[0003] Traditional RFID tags are made from thin metal films (such as aluminum or copper foil) through a metal etching process. The production process involves preparing the substrate, applying a photosensitive material, continuously exposing the material, developing the image, etching, stripping the film, washing, and drying. This method is complex and cumbersome, resulting in high costs, low material utilization, and the generation of large amounts of wastewater containing heavy metals, which poses a significant environmental risk.

[0004] In recent years, with the continuous advancement of RFID component manufacturing technology, printing-based RFID tag manufacturing methods have emerged on the market. These methods use gravure printing and other methods to print a liquid conductive paste onto a substrate according to a preset pattern. The paste is then dried and cured by heating, light curing, and other methods to produce a conductive RFID tag. For example, Invention 201810111964.1 discloses a method for preparing graphene conductive ink that can be used for RFID tags, and Invention 201910216604.2 discloses a graphene-based RFID antenna and a printing method thereof.

[0005] However, the conductive inks disclosed in the above-mentioned prior art for printing RFID electronic tags are all prepared based on water-based resins, and have slightly poor conductive performance during use. Due to the characteristics of the metal conductive powder and graphene itself, the slurry system has poor dispersion and uniformity, poor performance stability, and other problems. In addition, due to the slow drying speed of the water-based conductive slurry, it is difficult to match the gravure printing process, resulting in low production capacity.

[0006] Summary of the Invention

[0007] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a carbon-based composite conductive paste with a high conductive component content and ideal dispersion, uniformity, adhesion and stability, and a preparation method thereof. The RFID electronic tags printed using the conductive paste have excellent conductive properties and high consistency in product performance parameters.

[0008] The present invention provides an RFID composite conductive paste, which comprises the following components by weight: 10-25 parts of an oily special cross-linked resin, 30-50 parts of a metal conductive agent, 5-10 parts of a two-dimensional carbon-based material, 20-50 parts of an organic solvent, 10-20 parts of a quick-drying agent, and 2-5 parts of a leveling agent.

[0009] Preferably, the oily special cross-linked resin is an epoxy resin modified with polyurethane, and the carrier saturated solid content of the polyurethane modified epoxy resin in the oily system is ≥55%.

[0010] Preferably, the oily special cross-linked resin is further added with a high cohesive force chlorovinyl resin, wherein the dry film density of the high cohesive force chlorovinyl resin is ≥1.4 g / m 3 .

[0011] Preferably, the two-dimensional carbon-based material is a physical oily graphene slurry, wherein the number of graphene layers contained therein is 9 to 11 layers.

[0012] Furthermore, the physical method oily graphene slurry is prepared by the following steps: Step 1: mixing high-order intercalated graphite with divalent acid ester and oily special cross-linked resin to obtain an initial graphene slurry, wherein the high-order intercalated graphite has a magnification of 150-350 times and a purity of ≥99%;

[0013] Step 2: The initial graphene slurry is subjected to liquid phase exfoliation under high pressure to obtain a physical oily graphene slurry having 9 to 11 graphene layers.

[0014] Preferably, the metal conductive agent is a mixture of one or more of silver-coated copper powder, silver-coated nickel powder, nickel-coated copper powder, and modified conductive copper powder.

[0015] Preferably, the quick-drying agent is a mixture of one or more of ethyl acetate, butyl acetate, acetone, and cyclohexanone.

[0016] The present invention also provides a method for preparing an RFID composite conductive paste, which is used to prepare the above-mentioned RFID composite conductive paste, comprising the following steps:

[0017] S1: placing an oily special cross-linked resin and an organic solvent in a container, heating to 50°C and dispersing them at a dispersion frequency of 1800-2200 revolutions per minute for 50-70 minutes to obtain a conductive paste carrier;

[0018] S2: adding the two-dimensional carbon-based material and the metal conductive agent to the conductive paste carrier and stirring for 25-35 minutes to obtain a carbon-based composite conductive paste;

[0019] S3: adding a quick-drying agent and a leveling agent to the carbon-based composite conductive paste and dispersing the mixture at a dispersion frequency of 800-1200 revolutions per minute for a dispersion time of 25-35 minutes to obtain an RFID composite conductive paste;

[0020] S4: Grind the RFID composite conductive paste using a grinder.

[0021] Preferably, the grinder is a three-roll grinder, the distance between the rollers is 0.4-0.6 mm, and the grinding frequency is 1 time.

[0022] The present invention also provides an RFID electronic tag, comprising an insulating substrate and an RFID radio frequency circuit and a control chip fixed on the surface of the insulating substrate. The control chip is electrically connected to the RFID radio frequency circuit, and the RFID radio frequency circuit is made by gravure printing using the above-mentioned RFID composite conductive paste.

[0023] The present invention has at least the following beneficial effects:

[0024] (1) The RFID composite conductive paste provided by the present invention has a conductive component with a high solid content

[0025] By modifying and optimizing the resin carrier and graphene slurry, a better synergistic effect can be achieved compared to conventional materials. The solid content of the carrier is effectively increased, making the conductive slurry have a good ability to accommodate solid conductive components, ensuring that the RFID circuit pattern formed after drying and curing contains sufficient conductive components.

[0026] (2) The RFID composite conductive paste provided by the present invention has ideal dispersion and uniformity

[0027] The conductive paste carrier used in the present invention is an oily special cross-linked resin, and the oily graphene slurry prepared from a low-rate high-order intercalated graphite raw material acts as a filler for the metal conductive agent to form a composite conductive structure. The modified and optimized oily resin and oily graphene material ensure that the conductive components in the prepared RFID composite conductive paste have good dispersion and uniformity, thereby further improving the performance indicators of the RFID circuit and the final RFID electronic tag.

[0028] (3) The RFID composite conductive paste provided by the present invention has balanced and stable performance

[0029] The RFID composite conductive paste provided by the present invention has the ratio of its components and the preparation process parameters determined through a large number of experiments, ensuring that the fluidity and adhesion, quick-drying and bonding properties are in a balanced state, and the conductive paste has stable properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of an RFID electronic tag sample;

[0031] FIG2 is a microstructure of conventional graphene material;

[0032] FIG3 is a microstructure of a physical oily graphene slurry provided according to an embodiment of the present invention;

[0033] FIG4 is a partial enlarged view of FIG3;

[0034] FIG5 is a front view of an RFID electronic tag provided according to an embodiment of the present invention;

[0035] FIG6 is a side view of an RFID electronic tag provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, the present invention will be further described based on preferred embodiments with reference to the accompanying drawings.

[0037] In addition, various components in the drawings are enlarged or reduced in size for easier understanding, but this is not intended to limit the scope of protection of the present invention.

[0038] Words importing the singular include the plural and vice versa.

[0039] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or are the orientation or positional relationship in which the products of the embodiments of the present invention are usually placed when in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, in order to distinguish different units, words such as first and second are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance. Their names may be different in the detailed description of the present invention and the claims.

[0040] The terms used in this specification are intended to illustrate the embodiments of the present invention and are not intended to limit the present invention. It should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will have a clear understanding of the specific meanings of the above terms in the present invention.

[0041] In order to better illustrate the technical solution of the present invention, the process of manufacturing RFID electronic tags using printing methods is first introduced, and the problems and causes of conductive inks in the prior art are analyzed.

[0042] FIG1 is a schematic diagram of a specific RFID electronic tag sample. As shown in FIG1 , an RFID radio frequency circuit with a specific pattern is attached to an insulating substrate. The process flow for manufacturing the above-mentioned RFID electronic tag by printing generally includes the following steps:

[0043] Liquid conductive ink is poured or coated into the groove with the corresponding radio frequency circuit mirror pattern; the conductive ink in the groove is scraped flat by a scraper or other device and the conductive ink outside the groove is removed; the conductive ink is transferred to the insulating substrate by roller pressing or other methods to form a positive circuit pattern; the conductive ink is dried and cured to finally obtain an RFID electronic tag.

[0044] In order to obtain RFID electronic tags with excellent conductive properties and high product parameter consistency, the printing and manufacturing process of the above-mentioned RFID electronic tags has relatively strict performance requirements for the conductive paste used. The ideal conductive paste should have the following characteristics:

[0045] (1) High solid content with conductive components

[0046] Since the RFID radio frequency circuit printed using conductive paste needs to have good conductivity and reflection properties for ultra-high frequency radio waves, the paste should have the ideal ability to accommodate solid conductive components to ensure that the circuit pattern formed after drying and curing contains sufficient conductive components;

[0047] (2) The conductive component has ideal dispersion and uniformity

[0048] When the slurry can fully accommodate the conductive components, the distribution of the conductive components in the slurry will affect the conductive properties of the final RFID circuit and the consistency of product performance parameters. The conductive components need to be fully dispersed in the slurry to ensure that all parts have conductive components, and they also need to have good uniformity to avoid problems such as uneven distribution and agglomeration of the conductive components, which may cause unstable conductivity and signal reflection performance at different locations and reduced yield.

[0049] (3) The relationship between fluidity and adhesion, quick-drying and bonding is relatively balanced

[0050] The conductive paste must have good fluidity during the pouring process into the gravure printing plate to ensure the integrity of the circuit pattern, and good adhesion to ensure that the circuit can be firmly attached to the insulating substrate. It must also have quick-drying properties to meet the needs of large-scale mass production, and it must ensure that the conductive components in the paste are tightly bonded to prevent problems such as pattern breakage during rapid drying. Therefore, it is necessary to modify, optimize, and adjust the ratio and preparation process of each component to achieve the overall optimal effect.

[0051] (4) The conductive paste material has stable properties

[0052] Since conductive pastes contain various solid and liquid components with different properties, each component also needs to be modified and optimized to improve the affinity between the components, so as to avoid stratification, precipitation and other phenomena in the paste, which affect product stability.

[0053] However, various conductive inks or conductive pastes disclosed in the prior art all have various defects to varying degrees, mainly including:

[0054] (1) The conductive pastes used in the prior art are mostly prepared by simply physically mixing water-based resin with ordinary graphene materials and metal conductive agents (metal powders), and their conductive properties are slightly poor;

[0055] (2) Due to the characteristics of metal conductive powder and graphene, their specific surface area is large and the surface tension of the aqueous system is large. It is difficult for the aqueous resin to fully wet their surface, making it difficult for the entire slurry system to be dispersed evenly and prone to agglomeration, thereby affecting the conductivity and parameter consistency of the printed RFID circuit. In addition, stratification and precipitation are prone to occur when the slurry is left for a long time, resulting in a decrease in slurry stability.

[0056] (3) Due to the slow drying speed, water-based conductive paste is difficult to match with the gravure printing process, resulting in slow product production speed and difficulty in achieving large-scale mass production.

[0057] In order to solve the various defects of the conductive paste in the above-mentioned prior art, one aspect of an embodiment of the present invention provides an RFID composite conductive paste, which includes the following components by weight: 10-25 parts of an oily special cross-linked resin, 30-50 parts of a metal conductive agent, 5-10 parts of a two-dimensional carbon-based material, 20-50 parts of an organic solvent, 10-20 parts of a quick-drying agent, and 2-5 parts of a leveling agent.

[0058] Specifically, the above-mentioned oily special cross-linked resin is used as a matrix to carry the conductive component composed of a metal conductive agent and a two-dimensional carbon-based material to form an oily conductive slurry system. The two-dimensional carbon-based material is used to act as a filler for the metal conductive agent to form a composite conductive structure. The organic solvent is used to dilute and adjust the concentration and viscosity of the conductive slurry. The leveling agent is used to increase the fluidity of the conductive slurry. The quick-drying agent is used to speed up the drying speed of the conductive slurry.

[0059] In some preferred embodiments of the present invention, the oily special cross-linked resin is an epoxy resin modified with polyurethane. The polyurethane-modified epoxy resin has a higher carrier saturated solid content and a higher dry film density than conventional epoxy resins. The carrier saturated solid content in the oily system is ≥55%, and the dry film density is ≥1.2 g / m 3 .

[0060] Table 1 below lists the comparison of the performance of polyurethane-modified epoxy resin and conventional epoxy resin in terms of carrier saturated solid content.

[0061] Table 1 Comparison of carrier saturated solid content of polyurethane modified epoxy resin and conventional epoxy resin

[0062] In some embodiments of the present invention, the oily special cross-linked resin can be obtained by polyurethane-modifying the epoxy resin. Modifying the epoxy resin is a technique known to those skilled in the art. The operations, reactant ratios, and reaction conditions during the implementation process can be set according to the performance to be achieved.

[0063] In some embodiments of the present invention, the oily special cross-linked resin can also be obtained directly by purchasing finished products. For example, modified epoxy resin and / or modified polyurethane resin produced by Huntsman Corporation of the United States can be used as the oily special cross-linked resin. The above-mentioned thermoplastic resin produced by the company has excellent dispersibility, which can greatly reduce the amount of resin without affecting the dispersibility of the conductive paste, and then greatly increase the proportion of the conductive agent in the overall formula, thereby improving the conductivity of the overall paste and greatly improving the performance of the printed electronic label.

[0064] In some preferred embodiments of the present invention, a high cohesive force chlorovinyl resin is further added to the oily special cross-linked resin, wherein the dry film density of the high cohesive force chlorovinyl resin is ≥1.4g / m 3 .

[0065] Table 2 below lists the comparison of dry film density performance of polyurethane modified epoxy resin, high cohesive chlorovinyl resin and conventional epoxy resin.

[0066] Table 2 Comparison of dry film density of polyurethane modified epoxy resin, high cohesive chlorovinyl resin and conventional epoxy resin

[0067] Conventional epoxy resins have high viscosity, making them difficult to formulate into high-solids conductive paste carriers. They also suffer from poor fluidity, resulting in thick, low-density, and brittle films after curing. Because gravure printing uses shallow grooves (on the micron scale) and millimeter-scale pattern widths, conductive pastes based on conventional epoxy resins are prone to poor circuit conductivity and ultra-high frequency wave reflection characteristics when used in gravure-printed RFID circuits, as well as incomplete and easily broken circuit patterns.

[0068] The present invention adopts polyurethane-modified epoxy resin as the oily special cross-linked resin, and preferably adds high-cohesion chlorovinyl resin thereto. The above-mentioned oily special cross-linked resin serves as the conductive paste carrier. The polyurethane-modified epoxy resin contained in it has a higher saturated solid content than conventional epoxy resin, and can carry more conductive components per unit volume, thereby effectively improving the conductive performance and reflective properties of the printed circuit; the addition of high-cohesion chlorovinyl resin can not only reduce the viscosity of the paste, but also achieve a good dispersion effect on the powdered conductive components by increasing the cohesion of the paste, thereby effectively increasing the density after film formation, reducing the thickness of the dry film layer, and enhancing the flexibility of the dry film and its adhesion to the substrate.

[0069] In some embodiments of the present invention, phenoxy resin and / or polyester resin are further added to the oily special cross-linked resin. The advantages of phenoxy resin and polyester resin are that they help to disperse the conductive paste, making the appearance of the conductive paste more delicate and improving the printing performance of the conductive paste itself. The surface of the electronic label printed by gravure is smooth and flat, and the performance consistency is greatly improved.

[0070] In some preferred embodiments of the present invention, the metal conductive agent is a mixture of one or more of silver-coated copper powder, silver-coated nickel powder, nickel-coated copper powder, and modified conductive copper powder.

[0071] In some preferred embodiments of the present invention, the two-dimensional carbon-based material is a physical oily graphene slurry, wherein the number of graphene layers contained therein is 9 to 11 layers, and the physical oily graphene slurry is prepared by the following steps:

[0072] The first step is to mix high-order intercalated graphite with a divalent acid ester (DBE solvent) and an oily special cross-linked resin to obtain an initial graphene slurry, wherein the high-order intercalated graphite has a magnification of 150-350 times and a purity of ≥99%;

[0073] Step 2: The initial graphene slurry is subjected to liquid phase exfoliation under high pressure to obtain a physical oily graphene slurry with a graphene layer number of ≥9 layers and ≤11 layers.

[0074] Mixing graphene materials into the conductive paste used to print RFID electronic tags can serve as a filler for the metal powder of the metal conductive agent, so that the metal powder dispersed in the resin carrier can be effectively connected, further enhancing the conductive and reflective properties of the printed circuit through synergistic effects.

[0075] However, the graphene used in the prior art is conventional graphene. Figure 2 shows the microstructure of conventional graphene, which shows significant thickness inhomogeneity and agglomeration. Furthermore, conventional graphene has a wide and irregular range of layers. While the lower number of layers improves conductivity, their small particle size makes them difficult to fill. The higher number of layers significantly reduces conductivity. When these unoptimized conventional graphene materials are added to the conductive slurry, their disorganized microstructure prevents them from producing a good synergistic effect with the conductive metal powder and may even have a negative effect.

[0076] The graphene material added to the conductive slurry of the present invention is a physical oily graphene slurry that has been optimized. The initial graphene slurry is obtained by mixing a high-order intercalated graphite raw material with high purity at a low rate with a divalent acid ester. The slurry has a low rate, high purity, easy dispersion, and good intercalation effect. The initial graphene slurry is subjected to liquid phase exfoliation under high pressure to obtain a physical oily graphene slurry with about 10 graphene layers.

[0077] Figure 3 shows the microstructure of a physical-process oily graphene slurry provided in accordance with an embodiment of the present invention, and Figure 4 is a partial magnification of Figure 3. As can be seen from Figures 3 and 4, the physical-process oily graphene slurry used in the embodiments of the present invention has a more uniform thickness than conventional graphene materials, and its microstructure is optimized, with a more consistent number of layers. This enables it to simultaneously achieve excellent conductivity and filling properties, thereby creating a synergistic effect with the metal conductive agent, further improving the performance indicators of the RFID circuit.

[0078] Table 3 below lists a comparison of performance parameters of a physical method oily graphene slurry provided by a specific embodiment of the present invention and conventional graphene materials (wherein the proportion of graphene components, other component types and proportions, and preparation processes are the same). Figures 2, 3, and Table 3 demonstrate the improvements in microstructure, filling properties, and electrical conductivity of the oily graphene slurry provided by the embodiment of the present invention compared to conventional graphene materials used in the prior art.

[0079] Table 3 Performance comparison between physical oily graphene slurry and conventional graphene materials

[0080] In some preferred embodiments of the present invention, the quick-drying agent is a mixture of one or more of ethyl acetate, butyl acetate, acetone, and cyclohexanone. Adding the quick-drying agent to the conductive paste can accelerate the drying and curing of the printed RFID circuit, thereby increasing the production speed of RFID electronic tags.

[0081] In some preferred embodiments of the present invention, the quick-drying agent may also be isophorone, or a mixture of isophorone and one or more of the above-mentioned ethyl acetate, butyl acetate, acetone, and cyclohexanone. Isophorone not only has a quick-drying effect, but also assists in dispersing and reducing the viscosity of graphene and the metal conductive agent, which is beneficial to the fluidity of the entire slurry system and improves printing performance.

[0082] In some preferred embodiments of the present invention, by adding a leveling agent and adjusting the ratio of the leveling agent, the conductive paste can be fully filled in the groove and leveled, and the RFID circuit pattern transferred to the substrate can be ensured not to flow around and affect the accuracy of the pattern. The printed RFID electronic icon can be made to have uniform thickness, stable conductive performance, and high consistency.

[0083] In some preferred embodiments of the present invention, the organic solvent is a dibasic acid ester (DBE solvent).

[0084] A large number of experiments have shown that too high a resin content in the conductive paste will deteriorate the conductivity, while too high a metal conductive agent content will make the paste viscosity too high, making it difficult to prepare and not conducive to cost control. In addition, graphene and metal conductive agents used as fillers also have a strict proportional relationship. If the graphene content is too low, it will be difficult to effectively fill the gaps between the metal conductive agents, thereby reducing the conductive performance. If the content is too high, it will hinder the connection bridging between the metal conductive agents, thereby reducing the conductive performance.

[0085] The aforementioned multiple performance requirements mean that the performance of a conductive paste cannot be achieved by simply adding the conventional functions of its various components. In particular, when the performance and efficacy of different components affect each other, it is necessary to adjust the ratio and modify and optimize them to eliminate negative effects and amplify beneficial effects. The RFID composite conductive paste provided by the present invention has a strict ratio of its components and has modified and optimized the resin carrier and graphene paste to achieve a better synergistic effect than conventional materials.

[0086] Another aspect of the present invention provides a method for preparing an RFID composite conductive paste, which is used to prepare the above-mentioned RFID composite conductive paste, and is characterized in that it includes the following steps:

[0087] S1: placing an oily special cross-linked resin and an organic solvent in a container, heating to 50°C and dispersing them at a dispersion frequency of 1800-2200 revolutions per minute for 50-70 minutes to obtain a conductive paste carrier;

[0088] S2: adding the two-dimensional carbon-based material and the metal conductive agent to the conductive paste carrier and stirring for 25-35 minutes to obtain a carbon-based composite conductive paste;

[0089] S3: adding a quick-drying agent and a leveling agent to the carbon-based composite conductive paste and dispersing the mixture at a dispersion frequency of 800-1200 revolutions per minute for a dispersion time of 25-35 minutes to obtain an RFID composite conductive paste;

[0090] S4: Grind the RFID composite conductive paste using a grinder.

[0091] Grinding the RFID composite conductive paste with a three-roll grinder can further promote the uniform distribution of the conductive components, making it less likely to delaminate or precipitate during the printing process, thereby ensuring the stability of the paste's conductive properties and the consistency of the product.

[0092] However, when using a three-roll mill for grinding, the more grinding times the better, and the higher the grinding fineness the better. The reason is that inappropriate grinding times and roller spacing may even have a negative effect on the performance of the conductive slurry. The selection of the roller spacing needs to be determined by the mesh size of the metal conductive agent. In some specific embodiments of the present invention, the mesh size of the metal conductive agent is 400-600 mesh, and the preferred mesh size is 500 mesh. If the roller spacing is set too large, the metal conductive agent cannot be effectively ground and dispersed. If the spacing is set too small, the conductive structure of the metal powder and graphene will be destroyed. In addition, the unground conductive slurry will show stratification, making the conductivity of the product unstable. On the contrary, multiple grinding will lead to the destruction of the conductive structure. Due to the influence of the characteristics of graphene itself, multiple grinding will also cause coarsening and agglomeration, affecting the conductivity.

[0093] Table 4 below compares the effects of different grinding times on the performance of conductive pastes, with other preparation processes and parameters remaining the same. The performance comparisons listed in Table 4 reveal that the performance of conductive pastes that have not been triple-rolled and those that have been multiple-rolled are inferior to those that have been single-rolled. The reasons for this are: The conductive pastes that have not been triple-rolled exhibit significant stratification when printed on thin films, with observed agglomeration of the conductive components in the paste, resulting in an uneven dry film surface and deteriorated conductivity and consistency. The conductivity data significantly deteriorates after multiple roll-to-roll processes, primarily due to the destruction of the silver and nickel coatings in the silver-coated copper powder and nickel-coated copper powder, which reduces conductivity and deteriorates antioxidant properties. This deteriorates significantly after prolonged storage.

[0094] Table 4 Comparison of the effects of different grinding times on the performance of conductive paste

[0095] In some preferred embodiments of the present invention, the grinder is a three-roll grinder, the roller spacing is 0.4-0.6 mm, and the grinding number is 1. The preferred process parameters in the above grinding process are determined after analyzing a large amount of experimental data. By setting the roller spacing to 0.4-0.6 mm, the conductive components in the agglomerated state that still exist in the conductive slurry after rotation dispersion and stirring are further evenly distributed, and their stratification is eliminated. By limiting the number of grinding times, damage to the microstructure of the metal conductive agent is avoided to ensure a positive promotion effect on the performance of the conductive slurry.

[0096] Example 1

[0097] Prepare the RFID composite conductive paste using the following steps:

[0098] Step 1: Add 40 parts by weight of DBE solvent and 10 parts of an oily special cross-linked resin obtained by mixing polyurethane-modified epoxy resin and high-cohesion chlorovinyl resin into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0099] Step 2: Add 31 parts of flaky nano silver-coated copper powder (silver content of 10%) and 5 parts of graphene conductive paste to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0100] Step 3: Add 10 parts by weight of butyl acetate and 2 parts by weight of a leveling agent to the above carbon-based composite conductive paste, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0101] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.6 mm.

[0102] Example 2

[0103] Prepare the RFID composite conductive paste using the following steps:

[0104] Step 1: Add 31 parts by weight of DBE solvent and 10 parts of an oily special cross-linked resin obtained by mixing polyurethane-modified epoxy resin and high-cohesion chlorovinyl resin into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0105] Step 2: Add 38 parts of flaky nano silver-coated copper powder (silver content of 5%) and 6 parts of graphene conductive paste to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0106] Step 3: Add 12 parts by weight of butyl acetate and 3 parts of a leveling agent to the above carbon-based composite conductive paste, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0107] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.5 mm.

[0108] Example 3

[0109] Prepare the RFID composite conductive paste using the following steps:

[0110] Step 1: Add 20 parts of DBE solvent and 11 parts of polyurethane-modified epoxy resin by weight into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0111] Step 2: Add 38 parts of flaky nano silver-coated copper powder (silver content of 3%) and 8 parts of graphene conductive paste to the above conductive paste by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0112] Step 3: Add 14 parts of butyl acetate and 4 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0113] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.4 mm.

[0114] Example 4

[0115] Prepare the RFID composite conductive paste using the following steps:

[0116] Step 1: Add 31 parts of DBE solvent and 10 parts of polyurethane-modified epoxy resin by weight into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0117] Step 2: Add 41 parts of flaky nano nickel-coated copper powder (nickel content of 5%) and 3 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0118] Step 3: Add 12 parts by weight of butyl acetate and 3 parts of a leveling agent to the above carbon-based composite conductive paste, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0119] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.5 mm.

[0120] Example 5

[0121] Prepare the RFID composite conductive paste using the following steps:

[0122] Step 1: Add 24 parts of DBE solvent and 11 parts of polyurethane-modified epoxy resin by weight into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0123] Step 2: Add 43 parts of modified flaky nano copper powder and 4 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0124] Step 3: Add 14 parts of ethyl acetate and 4 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain RFID composite conductive paste.

[0125] Step 4: The RFID composite conductive paste is roll-milled twice using a three-roll mill, wherein the distance between the rolls is 0.4 mm.

[0126] Example 6

[0127] Prepare the RFID composite conductive paste using the following steps:

[0128] Step 1: Add 24 parts by weight of DBE solvent and 11 parts of an oily special cross-linked resin obtained by mixing polyurethane-modified epoxy resin and high-cohesion chlorovinyl resin into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0129] Step 2: Add 43 parts of flaky nano silver-coated copper powder (silver content of 3%) and 4 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0130] Step 3: Add 14 parts of butyl acetate and 4 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0131] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.4 mm.

[0132] Example 7

[0133] Prepare the RFID composite conductive paste using the following steps:

[0134] Step 1: Add 20 parts of DBE solvent and 10 parts of modified polyurethane resin by weight into a stirring tank, heat to 50°C, and stir with a dispersion plate at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0135] Step 2: Add 53 parts of flaky nano silver-coated copper powder (silver content of 10%) and 5 parts of graphene conductive paste to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0136] Step 3: Add 5 parts of butyl acetate, 5 parts of isophorone and 2 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0137] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.4 mm.

[0138] Example 8

[0139] Prepare the RFID composite conductive paste using the following steps:

[0140] Step 1: Add 20 parts of DBE solvent and 10 parts of saturated polyester resin by weight into a stirring tank, heat to 50°C, and stir with a dispersion disk at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0141] Step 2: Add 53 parts of flaky nano silver-coated copper powder (silver content of 10%) and 5 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0142] Step 3: Add 5 parts of butyl acetate, 5 parts of isophorone and 2 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0143] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.5 mm.

[0144] Example 9

[0145] Prepare the RFID composite conductive paste using the following steps:

[0146] Step 1: Add 20 parts of DBE solvent, 2 parts of phenoxy resin and 8 parts of modified polyurethane resin in a stirring tank by weight, heat to 50°C, and stir with a dispersion disk at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0147] Step 2: Add 53 parts of flaky nano silver-coated copper powder (silver content of 10%), 2 parts of graphene conductive paste and 3 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0148] Step 3: Add 6 parts of butyl acetate, 4 parts of isophorone and 2 parts of leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0149] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.4 mm.

[0150] Example 10

[0151] Prepare the RFID composite conductive paste using the following steps:

[0152] Step 1: Add 20 parts of DBE solvent, 4 parts of saturated polyester resin and 6 parts of modified polyurethane resin in a stirring tank by weight, heat to 50°C, and stir with a dispersion disk at a frequency of 2000 revolutions per minute for one hour to prepare a conductive slurry carrier.

[0153] Step 2: Add 53 parts of flaky nano silver-coated copper powder (silver content of 10%), 3 parts of graphene conductive paste and 2 parts of highly filled conductive carbon black to the above conductive paste carrier by weight, and continue stirring for 30 minutes to obtain a carbon-based composite conductive paste.

[0154] Step 3: Add 15 parts of isophorone and 2 parts of a leveling agent to the above carbon-based composite conductive paste by weight, and continue stirring for 30 minutes to obtain an RFID composite conductive paste.

[0155] Step 4: The RFID composite conductive paste is roll-milled once using a three-roll mill, wherein the distance between the rolls is 0.5 mm.

[0156] Table 5 below lists the performance comparison of the conductive pastes for RFID printing prepared according to preferred embodiments 2, 3, 7 and 8 and the conductive paste prepared using conventional technology.

[0157] Table 5 Performance comparison of conductive pastes prepared by preferred embodiments of the present invention and conventional techniques

[0158] Another aspect of the embodiments of the present invention further provides an RFID electronic tag. Figures 5 and 6 respectively show a top view and a side view of the RFID electronic tag according to the embodiment of the present application. As shown in Figures 5 and 6, the RFID electronic tag provided by the present invention includes an insulating substrate 10 and an RFID radio frequency circuit 11 fixed to the surface of the insulating substrate and a control chip 12. The control chip 12 is electrically connected to the RFID radio frequency circuit 11, and the RFID radio frequency circuit 11 is made by gravure printing using the above-mentioned RFID composite conductive paste.

[0159] Specifically, the above-mentioned RFID composite conductive paste can be first poured into the groove of the gravure printing roller and scraped flat (wherein the groove pattern is a mirror image pattern of the RFID radio frequency circuit 11 to be produced), and then the RFID composite conductive paste in the groove is transferred to the insulating substrate 10 by rolling between the gravure printing roller and the embossing roller to form the RFID radio frequency circuit 11. Finally, the control chip 12 is fixed to the insulating substrate 10 by bonding or the like, and electrically connected to the RFID radio frequency circuit by welding or the like (the connector 121 in Figures 5 and 6 is the connection portion between the control chip 12 and the RFID radio frequency circuit 11). The above-mentioned method of making RFID electronic tags by gravure printing is already known to those skilled in the art and will not be repeated here.

[0160] FIG5 shows a specific pattern of an RFID radio frequency circuit 11. It is easy to know that, when actually manufacturing an RFID electronic tag, those skilled in the art can select or change the specific pattern of the RFID radio frequency circuit and the specifications and models of the control chip according to actual needs. The above selection and change do not deviate from the scope of protection of the claims of the present invention.

[0161] The above is a detailed introduction to the specific embodiments of the present invention. For those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A RFID composite conductive paste, characterized in that: Calculated by weight, it includes the following components: 10-25 parts of oily special cross-linked resin, 30-50 parts of metal conductive agent, 5-10 parts of two-dimensional carbon-based material, 20-50 parts of organic solvent, 10-20 parts of quick-drying agent, and 2-5 parts of leveling agent.

2. The RFID composite conductive paste according to claim 1, characterized in that: The oily special cross-linked resin is an epoxy resin modified with polyurethane, and the carrier saturated solid content of the polyurethane modified epoxy resin in the oily system is ≥55%.

3. The RFID composite conductive paste according to claim 2, characterized in that: The oily special cross-linked resin is further added with a high cohesive force chlorovinyl resin, and the dry film density of the high cohesive force chlorovinyl resin is ≥1.4g / m 3 .

4. The RFID composite conductive paste according to claim 1, characterized in that: The two-dimensional carbon-based material is a physical oily graphene slurry, which contains 9 to 11 graphene layers.

5. The RFID composite conductive paste according to claim 4, characterized in that: The physical method oily graphene slurry is prepared by the following steps: The first step is to mix high-order intercalated graphite with a divalent acid ester and an oily special cross-linked resin to obtain an initial graphene slurry, wherein the high-order intercalated graphite has a magnification of 150-350 times and a purity of ≥99%; Step 2: The initial graphene slurry is subjected to liquid phase exfoliation under high pressure to obtain a physical oily graphene slurry having 9 to 11 graphene layers.

6. The RFID composite conductive paste according to claim 1, characterized in that: The metal conductive agent is a mixture of one or more of silver-coated copper powder, silver-coated nickel powder, nickel-coated copper powder, and modified conductive copper powder.

7. The RFID composite conductive paste according to claim 1, characterized in that: The quick-drying agent is a mixture of one or more of ethyl acetate, butyl acetate, acetone and cyclohexanone.

8. A method for preparing an RFID composite conductive paste, for preparing the RFID composite conductive paste according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: placing an oily special cross-linked resin and an organic solvent in a container, heating to 50°C and dispersing them at a dispersion frequency of 1800-2200 revolutions per minute for 50-70 minutes to obtain a conductive paste carrier; S2: adding the two-dimensional carbon-based material and the metal conductive agent to the conductive paste carrier and stirring for 25-35 minutes to obtain a carbon-based composite conductive paste; S3: adding a quick-drying agent and a leveling agent to the carbon-based composite conductive paste and dispersing the mixture at a dispersion frequency of 800-1200 revolutions per minute for a dispersion time of 25-35 minutes to obtain an RFID composite conductive paste; S4: Grind the RFID composite conductive paste using a grinder.

9. The method for preparing an RFID composite conductive paste according to claim 7, wherein: The grinding machine is a three-roll grinding machine, the distance between the rollers is 0.4-0.6 mm, and the grinding frequency is 1 time.

10. An RFID electronic tag comprising an insulating substrate, an RFID radio frequency circuit fixed to a surface of the insulating substrate, and a control chip, wherein the control chip is electrically connected to the RFID radio frequency circuit, characterized in that: The RFID radio frequency circuit is made by gravure printing using the RFID composite conductive paste as claimed in claim 1.

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