A formulation of graphene coating and capacitive coating process for creating smart metal sheet proofing

Abstract

The present invention relates to the development of coating formulation or graphene printing ink, and capacitive coating process wherein the conductive ink has been developed having at least 2 specific layers in order to use for create virtual charge storage values to occur on metal sheet, both conductive and non-conductive backgrounds. This development has been used for smart metal sheet which has the outstanding properties, for examples, antibacterial and antifungal property, electromagnetic shield property, rapid water absorption and transportation property, water-impermeable and vapor-permeable property, UV protection property, and antistatic property.

Description

[0001] A FORMULATION OF GRAPHENE COATING AND CAPACITIVE COATING

[0002] PROCESS FOR CREATING SMART METAL SHEET PROOFING

[0003] Field of the invention

[0004] Material science, especially related to a formulation of graphene coating and capacitive coating process for creating smart metal sheet proofing.

[0005] Background of the invention

[0006] Construction materials with special properties and functional and smart materials are increasingly popular and widely researched. Such materials are designed to offer protection against environmental conditions, for examples, thermal and UV protection material from sun, electromagnetic shield and antistatic materials. Such materials have the following properties including: (1) antibacterial material for general use, (2) climate and environment protection material, (3) electromagnetic shield materials, (4) rapid water absorption and transportation materials, (5) water-impermeable and vapor-permeable materials, (6) UV protection materials, (7) antistatic materials, (8) far-infrared radiation absorption materials, and (9) water-repellent materials.

[0007] It does not appear to disclose coating agent or graphene ink applied directly onto metal sheets. Therefore, this invention directs to develop metal sheet coating with materials or material mixture to enhance functional properties, for examples, graphene with excellent electrical and thermal conductivity, high tensile strength which is stronger than steel at similar thickness, and high flexibility which allow to bend and fold without molecular damages. Graphene is material having conductivity and self-charge suitable for capacitive applications. Presently, there is development of conductive ink via printable electronic technology, from simple materials to printed materials, which many companies and organizations are interested in due to the perceived opportunity in the expansion of the industry and lower production costs, compared with complementary metal-oxide semiconductor (CMOS) or traditional microelectronics, in terms of lower production cost to market accessibility, and cause the novel applications or novel products. This is known that materials for the electric and thermal conductivity improvement to conductive ink are, for example, silver nanoflakes which has high conductivity but expensive. Manufacturers therefore still use copper as conductive ink since it is cheaper and low resistant, but is prone to occur the oxidation on surface. Manufacturers also use carbon instead of copper as conductive material since it is cheaper than silver, but low adhesive property on surface. Previously, conductive ink can be only used in glass and ceramics, and then used in polymer or metal sheet respectively, and can be used in various applications in printed technology, for examples, inkjet, flexography, offset, or screen printings. The integration of various printing technologies allows to create capacitive graphene printed materials, which illustrated in the following exemplary prior arts.

[0008] U.S. patent application US20120306813A1 “system and method for retrieving information from an information carrier by means of a capacitive touch screen” discloses a principle of data transmission through a capacitive screen using a printing technique from conductive ink printed on an insulating material. The inventor has developed a model and demonstrated the use of such technology for use and by developing a card model for creating data to encode various data. However, it still requires human hands, in the development process, to touch since the structure of the encoding pattern on the card is not designed by referring to the structure of the capacitive screen, resulting in insufficient charge at the point where the conductive ink is not able to accumulate charge sufficiently. Therefore, it is necessary to rely on the transfer of charge from the human body to use collaboratively.

[0009] U.S. patent application US20140342809A1 “systems and methods for transmitting information using capacitive ink” discloses a principle of developing conductive ink printing for creating a structure and use the structure of such printing to design the data transmission from one material to the data that can be processed by focusing on creating a database of codes for comparison with the data generated from electronic printing. When the data read from the capacitive screen can be read and matched with the previously recorded database, the conductive ink will be as if it has sent data for decoding.

[0010] U.S. patent application US20170300722A1 “Reduced ink coverage of printed electronic designs by alternative fill patterns comprising ray and grid patterns” discloses a development of the reading of the position of the conductive ink printing from the printing on the non-conductive material by creating a specific printing pattern that focuses on the pattern form to create a virtual ground on the same layer as the conductive ink layer used to identify the touch position on the capacitive screen. This method still requires additional human hand touch to create a virtual ground with a size sufficient to create a capacitive value, and printing with this method may cause the printing structure used to create the virtual ground to become a contact point itself. In addition, this technique cannot separate or control the capacitance of the charge storage to create the virtual ground. This method can only appear and display on the screen.

[0011] Therefore, this invention is directed to the integration of conductive ink technology and thermal conductivity from graphene, printing technology, and technology for creating materials from capacitive graphene ink printing process on metal sheet materials, in order to produce the metal sheet having specific properties, for examples, antibacterial and antifungal property, thermal protection property, noise protection property, rapid water absorption and transportation property, water-impermeable and vapor-permeable property, UV protection property, and antistatic property.

[0012] Summary of the invention

[0013] This invention is directly related to the development of conductive and thermal ink formulas mixed with graphene, and capacitive printing process to create smart metal sheet materials with conductive ink deposition on metal sheet. The development of conductive ink printing with specific characteristics has been used to create virtual charge storage values to occur on metal sheet, both conductive and non-conductive backgrounds. The printing of dots result in different conductive layers. When the printing pattern is inducted, the charge moves from one position to another position, which results in charge transfer, create a virtual ground condition, and obtain the metal sheet having capacitive properties. From the properties of the conductive ink and the conductive printing background, it is possible to control the amount of charge transfer that can be transferred from the ink dot area to the background by the number of layers, thickness and size of the printed dots, which controls the amount of charge storage of working the ink on the materials. This makes the metal sheet printed with capacitive properties show special or intelligent metal sheet, for examples, antibacterial properties, electromagnetic shield property, rapid water absorption and transportation property, water-impermeable and vapor-permeable property, UV protection property, and antistatic property.

[0014] Various purposes and features of the present invention will become clearer when considered together with the accompanying drawings and the best detailed description of the invention which will be described below.

[0015] Brief description of the drawings

[0016] Figure 1 illustrates a printed pattern of conductive ink on a metal sheet. Detailed description of the invention

[0017] This description of this invention will be made by illustrating the invention and referring to it by means of drawings and photographs to illustrate and clarify the description, and identical parts in these drawings will be represented by the same reference numbers. This is without any limitation and the scope of the invention will be in accordance with the appended claims.

[0018] According to the present invention, the development of a formula for graphene conductive ink, the printing pattern, and the structure for printing conductive ink on the material as shown in Figure 1 is an example fabric coated with two types of graphene conductive ink with different electric conductivity overlapping each other. The process includes the following steps.

[0019] (A) Mixing 1-15 % by weight of binders with 1-10% by weight of graphene, wherein the binders can be selected from polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyacrylic acid, polyacrylate, or a combination thereof, preferable polyacrylic acid.

[0020] (B) Graphene is adding a functional group which selected from oxygen, nitrogen, ammonia, carboxylic acid, argon, or a combinations thereof, preferable oxygen, which has been subjected to plasma polymerization in order to improve the surface of materials by destabilizing the gas molecules, or continuously activating as ions, electrons, which react with the surface of the material or substrate in order to form a thin film adhering to the said surface in the reactor.

[0021] (C) Mixing 0.1-5 % by weight of dispersing agent to above mixtures to assist the dispersion of the mixture, reduce agglomeration and prevent sedimentation. The dispersing agents can be selected from acrylate copolymers, polar compounds, acrylate derivatives, affnic dyes, carboxylic acid derivatives, acrylate compounds, or a combination thereof, preferable the acrylate compound.

[0022] (D) Mixing the mixtures obtained from the above process to a matrix liquid containing 85-95% by weight as a solvent which selected from aqueous solvents, organic solvents, or a combination thereof, preferable the aqueous solvent.

[0023] (E) Homogenizing the mixture by using a three-roll mill, one-step ultrasonic waves, or a combination thereof in order to produce graphene-containing nanoparticles aligned their molecules in a planar, which results in high efficiency in dispersing the graphene-containing mixture in viscous liquids as screen printing inks. (F) The conductive ink is then coated and printed on the metal sheet by a dipcoating or spraying process in such a way that at least two layers of different types of inks bonded together by an adhesive mechanism, wherein comprises a printing layer 202 and a substrate 203, wherein one example of the substrate 203 is a metal sheet, wherein the conductive ink 5 is printed on the printing layer 202, as shown in Figure 1. The process further comprises covering pattern of the conductive ink 5 with an insulating material 201.

[0024] (G) For the printing pattern of conductive ink 5 on the substrate 203, there are 2 patterns of charge storage changes as shown in Figure 1. The conductive ink in each layer has different conductive properties in order to transfer charges resulting from capacitive induction. The basic structure of the capacitor is a device used to charge and discharge by placing two conductive materials in parallel, close to each other, but not connected to each other. Between the two conductors, there will be a barrier called dielectric, which can be selected from air, mica, plastic, ceramic, or other insulating materials. From the above principle in this invention, the conductive material as a conductive ink is compared, and the dielectric or insulator part is replaced by conductive ink, which has different properties from the conductive ink in the first part. Normally, general capacitor is an insulator, and has non-conductive property. On the other hand in this invention, the conductive ink is used by replacing the insulating layer due to the fact that the conductive ink has poor electric conductivity compared to general conductive substance in capacitors, which cause the charge transfer from the conductive substance has occurred to cross the insulator difficultly and the amount of charge will be less. Therefore, conductive ink in this invention has been tested with low conductivity as an insulator instead of general insulators. The printing structure in this invention is classified in two types, that is, the structure with a background of conductive material, and the structure with a background of non-conductive material. Both types have the same principle, but there are slightly different details in printing the conductive ink layer. In the case of printing for use with a conductive background, the number of screen layers are reduced by one layer, but in the case of use on other non-conductive materials, an additional background layer are coatdipped or sprayed to increase the charge transfer that will occur.

[0025] (H) In the printing process, the printing is classified in 2 layers by using coatdipping or spraying, which includes one layer of background and one layer of foreground pattern overprinted in the background, wherein the conductive ink in the background is provided in a rectangular shape by at least one layer of 1 -round screen-printing with graphene paste with a conductivity in the range of 100-500 ohm / sq. Then, the above background layer is overprinted with carbon paste with a conductivity in the range of 500- 1,500 ohm / sq and a thickness of 1-1.15 micron, with each layer having a different thickness and conductivity.

[0026] Although the present invention has been described in detailed description by means of the attached drawings, it is understood that modifications or alterations by a person who skilled in the art and science, within the scope and purpose of the invention, can be made. The scope of the present invention shall be in accordance with the embodiment of the invention as stated in the appended claims, including aspects of the invention, although it is not specifically stated in the claims, have a utility and produce results similar to those of the invention as stated in the claims.

[0027] Best mode for carrying out the invention

[0028] Best mode or preferred embodiment of the invention is as provided in the description of the invention.

Claims

Claims1. A formulation of dip-coating and spraying conductive graphene ink that can produce pseudo-capacitance for a metal sheet, the formulation comprising: graphene 1-10% by weight; binder 1-15% by weight; dispersing agent 0.1-5% by weight; matrix liquid 85-95% by weight; and all components are mixed to complete 100% by weight.

2. The metal sheet made from dip-coating and spraying conductive graphene ink as claimed in claim 1, wherein the graphene has functional groups selected from oxygen, nitrogen, ammonia, carboxylic, argon, or a combination thereof.

3. The metal sheet made from dip-coating and spraying conductive graphene ink as claimed in claim 1, wherein the binder is selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), polyacrylic acid, polyacrylate, or a combination thereof.The metal sheet made from dip-coating and spraying conductive graphene ink as claimed in claim 1, wherein the dispersing agent is selected from acrylate copolymers, polar compounds, acrylate derivatives, affinic dyes, carboxylic acid derivatives, acrylate compounds, or a combination thereof.

5. The metal sheet made from dip-coating and spraying conductive graphene ink as claimed in claim 1, wherein the matrix liquid is selected from aqueous solvents, or organic solvents, or a combination thereof.

6. The metal sheet made from dip-coating and spraying conductive graphene ink as claimed in claim 1, wherein the method for preparing formulation comprises the step of: a) mixing the binder with the functionalized graphene; b) adding the dispersing agent to the mixtures from step a); c) adding matrix liquid to the mixtures from step b); and d) homogenizing graphene in liquid matrix by using a three-roll mill, or one-step ultrasonic waves, or a combination thereof.A printing by conductive ink as claimed in claim 1, providing two structural types of printing including structure having conductive ink background, and structure having non-conductive ink background.

8. The printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claim 7, performed by dip-coating or two-layer spraying, including one background layer of conductive ink, and one patterned layer overprinted to the background layer by non-conductive ink.

9. The printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claim 7-8, wherein the printing by conductive ink is provided by at least one layer dip-coating or spraying with graphene paste with conductivity in the range of 100-500 ohm per square, followed by at least one layer overprinted on carbon paste with conductivity in the range of 500-1500 ohm per square, and with thickness in the range of 1-1.5 micron.

10. A metal sheet with antibacterial and antifungal property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

11. A metal sheet with antistatic property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

12. A metal sheet with electromagnetic shield property wave property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

13. A metal sheet with rapid water absorption and transportation property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

14. A metal sheet with water-impermeable and vapor-permeable property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

15. A metal sheet with thermal and UV protection property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

16. A metal sheet with vibration and acoustic dampening property obtained by the printing by conductive ink as claimed in claim 1 according to types of printing as claimed in claims 7-9.

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