阅读说明：本技术 制作射频识别标签的天线的导电墨水组合物及制造方法 (Conductive ink composition for manufacturing antenna of radio frequency identification tag and manufacturing method thereof ) 是由 赖中平 于 2018-05-29 设计创作，主要内容包括：本发明提供一种制作射频识别标签的天线的导电墨水组合物及制造方法,该墨水组合物包括：含有石墨结构的片状导电碳材、导电填充料、分散剂和溶剂,依据天线的形状可以通过印刷或喷墨印刷的方式将该墨水组合物涂布于一纤维基材的表面形成一导电层,部份的该导电层渗入该纤维基材的纤维间的孔隙附着于该纤维基材,由该纤维基材和该导电层构成一种不含黏着剂(binder-free)的射频识别标签的天线结构；本发明的墨水组合物不含绝缘的黏着剂,故能提升天线结构的导电性、降低电阻和制作成本。(The invention provides a conductive ink composition for manufacturing an antenna of a radio frequency identification tag and a manufacturing method thereof, wherein the ink composition comprises the following components: the graphite-structure-containing sheet-shaped conductive carbon material, the conductive filler, the dispersant and the solvent are characterized in that the ink composition can be coated on the surface of a fiber base material in a printing or ink-jet printing mode according to the shape of the antenna to form a conductive layer, part of the conductive layer penetrates into pores among fibers of the fiber base material to be attached to the fiber base material, and the fiber base material and the conductive layer form an antenna structure of a radio frequency identification tag without an adhesive (binder-free); the ink composition does not contain an insulating adhesive, so that the conductivity of the antenna structure can be improved, and the resistance and the manufacturing cost can be reduced.)

1. A conductive ink composition for use in making an antenna for a radio frequency identification tag, comprising: the graphite-structure-containing sheet conductive carbon material comprises a graphite-structure-containing sheet conductive carbon material, a conductive filler, a dispersant and a solvent.

2. The conductive ink composition for manufacturing an antenna of an rfid tag according to claim 1, wherein the flake-shaped conductive carbon material comprises any one or a combination of more than one of graphene, natural graphite micro-flakes, and flake-shaped carbon black.

3. the conductive ink composition for making an antenna of an rfid tag of claim 1, wherein the conductive filler comprises any one or a combination of more than one of other shapes of conductive carbon material, conductive metal particles, conductive oxides, and conductive polymers.

4. The conductive ink composition for manufacturing an antenna of an RFID tag according to claim 3, wherein the conductive carbon material comprises any one or more of graphene, graphite, carbon nanotubes, carbon nanospheres and conductive carbon black.

5. The conductive ink composition for making an antenna of an RFID tag of claim 3, wherein the conductive metal particles comprise any one or a combination of more than one of platinum, gold, palladium, ruthenium, silver, copper, nickel, zinc or an alloy thereof.

6. The conductive ink composition for making an antenna of a radio frequency identification tag of claim 3, wherein the conductive oxide comprises any one or a combination of more than one of palladium oxide or ruthenium oxide.

7. The conductive ink composition for forming an antenna of an RFID tag according to claim 3, wherein the conductive polymer comprises one or more of polythiophene, polypyrrole, polyacetylene and polyaniline derivatives.

8. A method of manufacturing an antenna for a radio frequency identification tag, comprising: (1) preparing a porous fiber substrate; (2) preparing a conductive ink composition, the conductive ink composition comprising: the graphite-structured sheet conductive carbon material comprises a graphite-structured sheet conductive carbon material, a conductive filler, a dispersant and a solvent; (3) printing the conductive ink composition on the porous fiber substrate; (4) drying and curing the conductive ink composition printed on the porous fiber substrate to form a printed antenna; (5) and rolling the cured printed antenna.

9. The method of claim 8, further comprising a rolling step of rolling the printed antenna attached to the surface of the porous fiber substrate after the drying and curing step, wherein a thickness compression ratio of the printed antenna is 50-90% of an original total thickness of the porous fiber substrate and the printed antenna.

10. The method of claim 8, wherein the conductive carbon sheet comprises one or more of graphene, natural graphite flake, and carbon black sheet.

11. The method of claim 8, wherein the conductive filler comprises any one or more of conductive carbon material, conductive metal particles, conductive oxide, and conductive polymer with other shapes.

12. The method of claim 11, wherein the conductive carbon material comprises any one or more of graphene, graphite, carbon nanotubes, carbon nanospheres, and conductive carbon black.

13. The method of claim 11, wherein the conductive metal particles comprise any one or a combination of platinum, gold, palladium, ruthenium, silver, copper, nickel, zinc, or an alloy thereof.

14. the method of claim 11, wherein the conductive oxide comprises any one or a combination of palladium oxide or ruthenium oxide.

15. the method of claim 11, wherein the conductive polymer comprises one or more of polythiophene, polypyrrole, polyacetylene, and polyaniline derivatives.

Technical Field

The present invention relates to Radio Frequency Identification (RFID), and more particularly, to a conductive ink composition for manufacturing an antenna of an RFID tag and a method for manufacturing the antenna.

Background

The radio frequency identification system comprises two parts, namely a Reader and a radio frequency identification tag (also called an electronic tag), wherein the radio frequency identification tag mainly comprises an IC chip and an antenna. A common rfid tag is a passive tag, in which an antenna senses an electromagnetic wave emitted from a reader, converts the electromagnetic wave into a current to start an IC chip, and then the IC chip transmits a pre-stored data back to the reader to complete identification. Rfid systems are classified into low frequency tags (LH,125 or 134.2KHz), high frequency tags (HF,13.56MHz), ultra high frequency tags (UHF,868 to 956MHz), and Microwave tags (Microwave,2.45 ghz) according to the frequency range of electromagnetic waves, and generally, the higher the frequency, the longer the receiving distance, and the faster the speed.

The efficiency with which an antenna converts electromagnetic waves into electrical current determines the performance of the RFID, which in turn depends on the antenna pattern design and conductivity. Known methods for manufacturing antennas for rfid tags include copper foil or aluminum foil etching and screen printing. The advantages of copper (aluminum) foil etching include low resistance, high precision, good performance, but the process is complicated, the manufacturing time is long, the cost is high, the substrate usage is limited, and many highly contaminated chemicals such as etching solutions and cleaning solutions are used, and the process is not environment-friendly. The screen printing method is a fast and inexpensive method, and directly uses conductive ink to print on the substrate, and has less contamination and no etching process, so that more substrates can be selected. The disadvantage is that the electronic performance of the antenna is inferior to that of the etching method; such as unstable resistance, low conductivity, and poor adhesion. The improvement in performance depends on the characteristics of the conductive ink, so the advantages and popularity of the printing process are limited by the price and performance of the conductive ink. At present, metal is the main conductive substance in the conductive ink, and common metal comprises copper and silver, but copper is easy to oxidize, and the price of silver is high, so that the performance of the conductive ink is affected and the price is high. The adhesion of metal is also a problem, and since metal cannot be self-formed on a substrate, the adhesion of metal conductive ink depends on the adhesive added in the conductive ink, but the adhesive is mostly an insulator, which further affects the conductivity of the ink, and the addition of the adhesive makes it difficult to achieve both the adhesion and the resistivity.

Known conductive inks are known which make it possible to make antennas by means of printing, for example: in the published U.S. Pat. No. 2012/027736A1, a conductive ink is disclosed, which comprises at least one polymer binder in the conductive material composition to achieve good adhesion, and additional conductive materials such as metals, metal oxides, etc., and has a sheet resistance (sheet resistance) in the range of 0.001-500 ohm/sq.

Also disclosed in U.S. patent No. 2004/0175515a1, it is proposed that conductive inks composed of sheet material can be applied to rfid by letterpress and intaglio printing; polymers and resins are also used as adhesives, and the conductive materials are mainly carbon black, metals and metal oxides, and the sheet resistance is relatively poor at about 200 ohm/sq. In the approved U.S. patent 7017822, it is proposed to mix metal and resin and mold the conductive wires, the bonding of the conductive wires and the substrate is still resin or molded onto the resin substrate, the conductive material is mainly stainless steel, the carbon material is filler, and the sheet resistance can reach 5-25 ohm/sq. In the approved taiwan patent I434456 "method for manufacturing RFID antenna using non-woven lava fiber paper substrate", it is proposed to print the antenna with ink containing metal ions, and then to reduce the metal by electroless plating, and this method is limited to the substrate being non-woven lava fiber paper, which has a complex process and still uses metal as the main conductive material. In the published chinese patent CN101921505B, a conductive ink for radio frequency identification is proposed, in which the ink material adopts a mixture of silver nanowires and silver nanoparticles as a conductive filler, and 2-10% of epoxy resin is used, but the expensive price of the silver nanowires will increase the manufacturing cost of the conductive ink.

The published Chinese patent CN103436099 proposes a composite conductive ink, which contains flake silver powder, graphene and graphite flake, wherein the silver powder is used as a conductive material in most parts, and the film-forming resin is 5-30 wt%. In addition, as shown in table one, in other graphene composite conductive ink patents, all disclosures point out the need for conductive inks containing different high molecular weight adhesives. Although the polymer adhesive can effectively increase the adhesion of the conductive printing layer, the non-conductive property also affects the conductivity of the entire printing layer. Therefore, the present application provides a polymer-free adhesive conductive ink composition for an rfid tag antenna and a method for manufacturing the antenna.

Table one, different patents disclose a complete table of the composition formula of the graphene system conductive ink.

Disclosure of Invention

In order to solve the above problems of the known conductive ink, the present invention proposes a conductive ink composition for manufacturing an antenna of a radio frequency identification tag, which can be used for printing the antenna of the radio frequency identification tag.

The conductive ink composition for manufacturing the antenna of the radio frequency identification tag comprises the following components: the graphite-structure-containing sheet conductive carbon material comprises a graphite-structure-containing sheet conductive carbon material, a conductive filler, a dispersant and a solvent.

The manufacturing method of the antenna of the radio frequency identification tag comprises the following steps: preparing a porous fiber substrate; preparing a conductive ink composition, the conductive ink composition comprising: the graphite-structured sheet conductive carbon material comprises a graphite-structured sheet conductive carbon material, a conductive filler, a dispersant and a solvent; coating the conductive ink composition on the surface of the porous fiber substrate according to the shape of the antenna; the solvent of the conductive ink composition is evaporated by thermal drying to form a conductive layer on the surface of the porous fiber substrate, and part of the conductive layer penetrates into the pores between the fibers of the porous fiber substrate and is attached to the porous fiber substrate.

One embodiment of the method for manufacturing an antenna structure of the present invention includes a rolling step of rolling the conductive layer attached to the surface of the porous fiber substrate to a rolling compression ratio of 50 to 90% of the original thickness.

Among them, preferred embodiments of the conductive ink composition include: the graphite-structure-containing sheet conductive carbon material comprises a graphite-structure-containing sheet conductive carbon material, a conductive filler, a dispersant and a solvent. The conductive filler comprises conductive carbon materials with other shapes, conductive metal particles, conductive oxides and conductive polymers.

The conductive carbon material comprises any one or more of graphene, graphite, carbon nanotubes, carbon nanospheres and conductive carbon black.

Wherein, the conductive metal particles comprise any one or more of platinum, gold, palladium, ruthenium, silver, copper, nickel and zinc, or alloy.

Wherein the conductive oxide contains any one of palladium oxide or ruthenium oxide or a combination of one or more of them.

The conductive polymer comprises one or more of polythiophene derivatives, polypyrrole derivatives, polyacetylene derivatives and polyaniline derivatives.

In the carbon material in which the conductive ink composition adopts a sheet-like structure, the sheet-like structure carbon material may be stacked in an irregular bulky structure, and since the conductive ink composition containing the sheet-like structure carbon material (the conductive ink composition is basically a conductive paste) does not have a polymer binder therein, the sheet-like bulky structure may be further compacted by a rolling process and tightly bonded to each other by a van der waals force of molecular layers on the surface of the sheet-like structure carbon material. Because no insulating non-conductive high molecular adhesive exists in the pressed conductive carbon layer, compared with the traditional conductive paste containing the high molecular adhesive, a coating with lower conductivity can be obtained. In addition to the above-mentioned application as a conductive filler, the present application further proposes to utilize the characteristic that the carbon material stacked coating layer with a sheet structure forms a dense layer after rolling, and use the carbon material with a sheet structure as a conductive adhesive to catch other conductive fillers. Adding other conductive fillers into the conductive ink composition without the high molecular adhesive, and dispersing the other conductive fillers in a loosely stacked flaky carbon material network structure; and then rolling to tightly compact the network structure formed by the carbon material with a sheet structure, and tightly holding other conductive fillers by the network structure to form a conductive layer without a polymer adhesive, wherein the antenna of the radio frequency identification tag is formed by the conductive layer without the polymer adhesive.

The conductive ink composition of the rfid tag of the present invention does not contain an insulating adhesive, and thus the conductivity of the conductive ink can be improved, the antenna structure prepared by coating the conductive ink composition on the surface of the porous fiber substrate has the effects of reducing the resistance and the manufacturing cost, and the density and the conductivity of the conductive layer can be further improved by the matching of the conductive paste prepared from the conductive ink composition and the porous fiber substrate through a rolling process.

other features and embodiments of the present invention will be described in detail below with reference to the drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a cross-sectional configuration view of an antenna of the radio frequency identification tag of the present invention;

FIG. 2 is a schematic view of the microstructure of FIG. 1 at position II showing the co-filming of the sheet-like conductive carbon material and the porous fibrous substrate;

FIG. 3 is a process diagram of the manufacture of an antenna for an RFID tag according to the present invention;

FIG. 4 is a schematic diagram of an antenna of the RFID tag of the present invention;

FIG. 5 is a graph of signal gain at different frequencies for an antenna of an RFID tag of the present invention.

Description of the symbols

10 porous fibrous base 20 conductive layer

21 sheet-like conductive carbon material

Detailed Description

The positional relationship described in the following embodiments includes: the top, bottom, left and right, unless otherwise indicated, are based on the orientation of the elements in the drawings.

One embodiment of the present conductive ink composition for making an antenna of a radio frequency identification tag comprises: the conductive ink composition comprises a graphite-structured sheet-like conductive carbon material, a conductive filler, a dispersant and a solvent, wherein the solid content of the conductive ink composition accounts for 2-85% (wt%) of the conductive ink. Wherein the flake conductive carbon material accounts for 10-90% (wt%) of the total solid, and is generally in the form of powder, and the flake conductive carbon material comprises graphene, graphite micro-flakes, natural graphite, and flake carbon black (such as KS 6); the conductive filler accounts for 10-90% (wt%) of the total solid, and the conductive filler comprises any one or more of conductive carbon materials, conductive metal particles, conductive oxides and conductive polymers in other shapes; the conductive carbon material in other shapes comprises any one or more of graphene, graphite, carbon nanotubes, carbon nanospheres and conductive carbon black; the conductive metal particles comprise any one or more of platinum, gold, palladium, ruthenium, silver, copper, nickel and zinc or an alloy; the conductive oxide contains any one or a combination of more than one of palladium oxide or ruthenium oxide; the conductive polymer comprises one or more of polythiophene derivatives, polypyrrole derivatives, polyacetylene derivatives and polyaniline derivatives. The dispersant is 0.0001-10 wt% of total solids, and may be an ionic dispersant or a non-ionic dispersant, the ionic dispersant comprises any one or a combination of more than one of P-123, Tween20, Xanthan gum, Carboxymethyl Cellulose (CMC), Triton X-100, Polyvinylpyrolidone (PVP), and Brji 30, wherein the non-ionic dispersant comprises any one or a combination of more than one of Poly (Sodium 4-Phenylenesulfonate) (PSS), 3- [ (3-Chlorometropyl) dimethyl ammonium ] -1-Propane Sulfonate (PS), Hexadecylmethylalametonium bromide (HTAB), Sodiumtaurodeoxycholate hydrate (SDS), 1-Pyreneacetate (PBA).

The solvent may be pure water or an organic solvent comprising: N-Methyl-2-pyrollidone (NMP), IPA (isopropyl alcohol), ethanol, glycerol, ethylene glycol, butanol, propanol, Propylene Glycol Monomethylether (PGME), and Propylene glycol monomethylether acetate (PGMEA).

Referring to fig. 1 and 2, an antenna structure of a radio frequency identification tag of the present invention includes: a porous fiber substrate 10 and a conductive layer 20, the composition of the conductive layer 20 includes: the graphite-structure-containing flake conductive carbon material comprises 10-90 wt% of flake conductive carbon material, 10-90 wt% of other conductive fillers and 0.0001-10 wt% of dispersant, wherein the weight ratio of the flake conductive carbon material to the total solid is 10-90 wt%, and the weight ratio of the dispersant to the total solid is 0.0001-10 wt%.

Please refer to fig. 3, which illustrates steps of a method for manufacturing an antenna structure of a rfid tag according to the present invention, including:

1. Preparing a porous fiber substrate 10, the porous fiber substrate 10 comprising: any one of general paper, hemp paper and Polyethylene Terephthalate (PET for short);

2. Preparing a conductive ink composition without a polymer binder, in particular a conductive ink composition without a polymer binder, the conductive ink composition comprising: the conductive ink composition comprises a flake conductive carbon material with a graphite structure, a conductive filler, a dispersant and a solvent, wherein the flake conductive carbon material accounts for 10-90% (wt%) of the total solid weight, the conductive filler accounts for 10-90% (wt%) of the total solid weight, the dispersant accounts for 0.0001-10% (wt%) of the total solid weight, and the solid content of the conductive ink composition accounts for 2-85% (wt%);

3. The conductive ink composition is applied to the surface of the porous fiber substrate 10 according to the shape of the antenna, and the application may be performed by any one of printing (including any one of screen printing, letterpress printing, and gravure printing) and inkjet printing (inkjet printing); and

4. The solvent of the conductive ink composition is evaporated by thermal drying to form the conductive layer 20 on the surface of the porous fibrous substrate 10, and part of the conductive layer 20 penetrates into the pores between the fibers of the porous fibrous substrate 10 and adheres to the porous fibrous substrate 10.

5. After the drying and curing step, the conductive layer 20 attached to the surface portion of the porous fiber substrate 10 is compressed by rolling, and the thickness compression ratio is 50 to 90% of the original total thickness of the porous fiber substrate 10 and the printed antenna.

For the conductive paste containing the polymer resin adhesive, after curing, the conductive filler can be firmly gripped due to the curing shrinkage of the resin adhesive, so that a conductive layer with good adhesion is obtained. As shown in the following table two, compared with the graphene/metal composite conductive paste without the polymer resin adhesive, in the conductive layer obtained from the commercial epoxy resin conductive silver paste, in the rolling process of the conductive filler firmly held by the polymer adhesive, the conductive filler is loosened from the originally firmly-adhered resin due to extrusion stress, and the adhesive is also diffused in the conductive filler due to extrusion to block the original conductive path, so that the resistance at two ends of the printed antenna is increased (2.1 ohm to 2.5 ohm, and the resistance after rolling is increased by 19%); in addition, the phenomenon that the high molecular resin is adhered to the roller in a reverse manner can also occur due to the overlarge rolling force, and the situation that part of the printed antenna is peeled from the base material and adhered to the roller is caused; therefore, the conductive paste containing the polymer adhesive is generally not subjected to the rolling process after being printed and cured. On the contrary, the conductive ink composition of the invention is basically prepared into a conductive paste, in particular to a conductive paste without a polymer adhesive, the conductive fillers can be contacted with each other more tightly by rolling, the non-conductive polymer adhesive does not resist in the middle, the terminal resistance of the printed antenna can be further greatly reduced (1.8 ohm is changed into 0.9 ohm, the resistance is reduced by 50 percent after rolling), and the adhesion of the whole conductive layer can be stabilized by the sheet carbon material structure after rolling; in addition, the problem of anti-sticking wheels due to excessive pressure is solved.

And secondly, the resistance of the commercial conductive silver paste containing the high-molecular adhesive and the resistance of the conductive paste without the high-molecular adhesive before and after rolling are measured.

As can be understood from the above description, the antenna structure of the rfid tag of the present invention is formed by applying the conductive ink composition on the surface of the porous fiber substrate 10 by printing or inkjet printing according to the shape of the antenna, and part of the conductive ink composition permeates into the fiber of the porous fiber substrate 10, because the sheet-shaped conductive carbon material 21 contained in the conductive ink has good film-forming property, the sheet-shaped conductive carbon material 21 can be co-film-formed with the porous fiber substrate 10 to achieve the adhesion effect without adding an adhesive (see fig. 2), and the porous fiber substrate 10 and the conductive layer 20 form the antenna structure of the rfid tag without metal and adhesive; the conductive ink composition does not contain an insulating adhesive, so that the conductivity of the antenna structure can be improved, and the resistance and the manufacturing cost can be reduced.

In one embodiment of the above method steps of the present invention, if the conductive ink composition is coated on the surface of the porous fiber substrate 10 by a screen printing method, wherein the screen mesh number is between 100-400 meshes, the printing precision can reach 100 μm; if the conductive ink composition is applied to the surface of the porous fiber substrate 10 by inkjet printing, the optimal printing precision can be even 0.1um level according to the positioning capability of the inkjet printing device. Fig. 4 is a schematic view of an antenna structure of an rfid tag printed with the conductive ink composition of the present invention, wherein the conductive layer 20 printed with the conductive ink composition of the present invention has an appearance that is not different from that of a conventional aluminum foil etching method, and the connection point between the conductive layer 20 and an IC chip has a precision of up to 10um without short circuit (see the partially enlarged structure of fig. 4). In another embodiment of the present invention, the conductive ink composition can be directly printed on paper to directly prepare a tear-down rfid tag, which can greatly simplify the complex processes of conventional metal etching and transferring.

In one embodiment of the present invention, the porous fibrous base material 10 can be selected from materials with high fiber density and large pores, and if the porous fibrous base material is paper, the basis weight of the paper is 30 to 200g/m2, the density is 0.5 to 2.5g/cm3, and the average pore diameter is 0.02 to 500 μm.

After the conductive layer 20 is printed, the solvent in the conductive ink is evaporated through a drying step, and one implementation mode of the drying method is a thermal drying method, wherein the heating temperature range is 50-300 ℃, and the heating time is shorter when the temperature is higher. In an embodiment of the method of the present invention, the method includes a rolling step, and after the drying step, the rolling method is used to roll and compress the conductive layer 20 attached to the surface of the porous fiber substrate 10 to 50-90% of the original thickness, so as to further improve the density and conductivity of the conductive layer 20. For the purpose of reducing the resistance, the conductive layer 20 can be coated thicker and the density of the conductive layer 20 is improved, so the flake conductive carbon material with thicker thickness and larger grain diameter can be selected, wherein the resistance of the flake conductive carbon material suitable for the radio frequency identification label is 0.1-50 ohm/sq (the resistivity is 1 x 10 < -6 > -2.5 x 10 < -4 > ohm-m).

Fig. 5 is a signal gain diagram of the antenna structure of the rfid tag of the present invention at different frequencies, which shows the signal gain (gain) obtained at each frequency by printing different antenna patterns on the surface of the porous fiber substrate 10 using the conductive ink composition without polymer adhesive of the rfid tag of the present invention. As can be seen from the comparison of the data in fig. 5, different antenna designs can provide specific signals in different frequency ranges for the rfid tag with specific frequencies, and the antenna structure printed on the surface of the porous fiber substrate 10 by using the conductive ink composition of the rfid tag of the present invention has very obvious signals in both the uhf and the microwave frequency ranges.

The antenna structure of the radio frequency identification tag is electrically connected with the IC chip, and the reading test of the reader is carried out. The antenna pattern of the tested antenna structure belongs to a common ultrahigh frequency design: the results of the sheet resistance and reading test of the two antenna structures are shown in table three, which confirms that the antenna structure printed on the surface of the porous fiber substrate 10 by using the conductive ink composition without the polymer adhesive of the rfid tag of the present invention is suitable for use in rfid tags of high frequency (HF,13.56MHz), ultra high frequency (UHF,868 to 956MHz) and Microwave (Microwave,2.45 ghz).

Reading test meter for electrically connecting antenna structure of three-meter radio frequency identification tag with IC chip

The above-described embodiments and/or implementations are only for illustrating the preferred embodiments and/or implementations of the present technology, and are not intended to limit the implementations of the present technology in any way, and those skilled in the art may make modifications or changes to other equivalent embodiments without departing from the scope of the technical means disclosed in the present disclosure, but should be construed as the technology or implementations substantially the same as the present technology.