Nano-silver transparent conductive thin film with shadow elimination function and preparation method of nano-silver transparent conductive thin film

Abstract

The invention belongs to the technical field of transparent conductive materials, and discloses a nano-silver transparent conductive thin film with a shadow eliminating function and a preparation method of the nano-silver transparent conductive thin film. The preparation method comprises the following steps: (1) weighing a silver nanowire solution, a solvent, water-based resin and an auxiliary agent, and preparing transparent conductive slurry; (2) printing the transparent conductive slurry prepared in the step (1) on a transparent substrate layer to form a transparent conductive layer; and (3) printing a sulfide solution on a preset non-conductive region of the transparent conductive layer for vulcanization treatment to form a transparent non-conductive region layer, and forming a transparent conductive region layer on a region not printed with the sulfide solution. According to the preparation method provided by the invention, the nano-silver transparent conductive film with the shadow elimination function can be efficiently and quickly prepared at low cost. According to the prepared nano-silver transparent conductive thin film, the difference value of optical transmittance and haze rate is smaller than or equal to 0.5%, and the nano-silver transparent conductive thin film is free of overall visual difference and excellent in shadow elimination and sensory effect.

Description

Technical Field

[0001] The invention belongs to the technical field of transparent conductive materials, and in particular relates to a nano silver transparent conductive film with a shadow elimination function and a preparation method thereof. Background Art

[0002] With the improvement of material standards, consumers' requirements for electronic products are developing in the direction of thinness, flexibility, visualization and touch control. At present, touch screens and related industrial chains are integrating into people's daily lives at a very fast speed. Transparent conductive films have good conductivity and high transmittance in the visible light band. In most practical applications such as touch screen films, transparent conductive films need to be patterned, that is, fixed conductive areas and insulating areas are formed on the surface of the substrate according to the graphic design.

[0003] At present, ITO (indium tin oxide) is still the mainstream transparent conductive material, and the alternative materials of ITO include nano silver wire, graphene, conductive polymer, carbon nanotube, etc. The proportion of new transparent conductive films based on ITO alternative materials in practical applications is increasing, but they have not yet been popularized in high-end applications such as small-sized mobile phones and tablets.

[0004] The transparent electrode area of ​​the capacitive touch screen needs to be patterned, and there are obvious differences in the chromaticity and refractive index between the transparent electrode area and the insulating area, and as the gap between the transparent electrode areas increases, the visibility becomes stronger. This result will lead to a large visual contrast when viewed at close range under strong light when used for small-sized touch screens, that is, inconsistency, which in turn affects the consumer experience. The original ITO transparent conductive film uses a method of reducing the line spacing and evaporating oxide to make the refractive index of the transparent conductive part consistent with that of the non-conductive area to achieve the shadow elimination effect. However, due to the difference in materials, the nano silver wire itself has an extremely slight light yellow color, and the nano silver wire itself has a haze that is visible to the naked eye under strong light, making the shadow elimination method of the ITO transparent conductive film difficult to use in nano-scale touch screens. The shadow elimination effect cannot be obtained in the silver wire transparent conductive film.

[0005] Although some shadow removal methods are disclosed in the prior art, such as using photoresist to protect the conductive area, applying filling liquid to fill the non-conductive area, and removing the photoresist with etching liquid, the process is complicated, requiring the application of photoresist first, then applying filling liquid, and removing the photoresist with etching liquid. Due to the complicated process steps, the efficiency of mass production is low; also because the photoresist, filling liquid, and etching liquid all require high costs, and the components in the etching liquid have a greater risk of polluting the natural environment, it is even more difficult to apply in the mass production process.

[0006] Therefore, developing a simple, fast, and low-cost method for eliminating shadows based on nanosilver wire transparent conductive film is of great significance for the application and promotion of new materials and promoting the application of new transparent conductive films in small and medium-sized touch screens such as mobile phones and tablets. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a nanosilver transparent conductive film with a shadow elimination function and a preparation method thereof. The preparation method provided by the present invention can efficiently, quickly and at low cost prepare a nanosilver transparent conductive film with a shadow elimination function; and the nanosilver transparent conductive film has no overall visual difference, and has excellent shadow elimination and sensory effects.

[0008] The invention provides a method for preparing a nano silver transparent conductive film with a shadow elimination function.

[0009] Specifically, a method for preparing a nano silver transparent conductive film with a shadow elimination function comprises the following steps:

[0010] (1) Weighing 1-20 parts of a nano silver wire solution, 50-95 parts of a solvent, 10-50 parts of an aqueous resin, and 0-1 parts of an additive by weight to prepare a transparent conductive paste; the diameter of the nano silver wires in the nano silver wire solution is 8-50 nm and the length is 10-30 μm; the concentration of the nano silver wire solution is 5-20 mg / mL;

[0011] (2) printing the transparent conductive paste prepared in step (1) on the transparent substrate layer to form a transparent conductive layer;

[0012] (3) Printing a sulfide solution on the preset non-conductive area of ​​the transparent conductive layer for sulfidation treatment The method comprises the following steps: forming a transparent non-conductive region layer with a square resistance greater than 5 MΩ, and forming a transparent conductive region layer with a square resistance less than 2000 Ω in the region where the sulfide solution is not printed; and the sulfide solution contains 0.1-10 mg / mL of sulfide.

[0013] Preferably, in step (1), the diameter of the silver nanowires in the silver nanowire solution is 10-40 nm, and the length is 15-25 μm.

[0014] Preferably, in step (1), the concentration of the nano silver wire solution is 8-15 mg / mL.

[0015] Preferably, in step (1), the nano silver wire solution uses one or more of isopropyl alcohol, ethanol, water, and propylene glycol methyl ether as solvent.

[0016] Preferably, in step (1), the solvent is selected from at least one of water, ethanol, ethylene glycol, n-butanol, ethyl acetate, propylene glycol methyl ether, glycerol, and diformic acid esters.

[0017] Preferably, in step (1), the water-based resin is selected from at least one of water-based polyurethane, water-based acrylic acid, carboxymethyl cellulose, water-based epoxy resin, amino resin, and polyethylene oxide.

[0018] Preferably, in step (1), the auxiliary agent includes a binder and / or a defoamer. The defoamer is silicone, polyether, mineral oil, etc.

[0019] Preferably, in step (1), 5-15 parts of nano silver wire solution, 60-80 parts of solvent, 10-30 parts of water-based resin, and 0-1 part of auxiliary agent are weighed in parts by weight to prepare a transparent conductive paste.

[0020] Preferably, in step (2), the transparent substrate layer includes one of polyethylene terephthalate (PET), glass, polyimide (PI), transparent polyimide (CPI), acrylic (PMMA), and polycarbonate (PC).

[0021] Preferably, in step (3), the sulfide is selected from at least one of sodium sulfide, sodium thiosulfate, ethionine, cysteine, mercaptoformic acid and thioethanol.

[0022] Preferably, in step (3), the sulfide solution uses one or more of water, ethanol and ether as solvent.

[0023] Preferably, in step (3), the concentration of the sulfide solution is 0.1-5 mg / mL; further preferably, in step (3), the concentration of the sulfide solution is 0.1-3 mg / mL.

[0024] Preferably, in steps (2) and (3), the printing method includes but is not limited to silk screen printing, coating, gravure printing, etc.

[0025] Preferably, in the preparation method, after the vulcanization treatment, a step of printing a transparent protective layer is further included. The step of printing a transparent protective layer is specifically: printing a protective layer ink on the transparent conductive region layer and the transparent non-conductive region layer, and curing to form a transparent protective layer. Covering the transparent conductive region layer and the transparent non-conductive region layer with a transparent protective layer can improve the scratch resistance, light protection and long-term stability of the nanosilver transparent conductive film.

[0026] Preferably, the protective layer ink includes at least one of polyurethane, acrylic acid, polyether and polycarbonate.

[0027] The invention also provides a nano silver transparent conductive film with shadow elimination function.

[0028] Specifically, a nanosilver transparent conductive film with shadow elimination function is prepared by the above preparation method, wherein the transmittance difference between the transparent conductive region layer and the transparent non-conductive region layer of the nanosilver transparent conductive film is ≤0.5%, and the haze rate difference is ≤0.5%.

[0029] The method for preparing a nanosilver transparent conductive film with a shadow-eliminating function provided by the present invention is to first print a transparent conductive paste containing nanosilver wires with a diameter of 8-50nm and a length of 10-30μm on a transparent substrate layer to form a transparent conductive layer; then print a sulfide solution on a preset non-conductive area of ​​the transparent conductive layer for sulfurization treatment to form a transparent non-conductive area layer with a square resistance greater than 5MΩ; and the area where the sulfide solution is not printed forms a transparent conductive area layer with a square resistance less than 2000Ω. The sulfide solution contacts the nanosilver in the preset non-conductive area on the transparent conductive layer, and the sulfur reacts chemically with the silver, and the resistance is sulfurized so that The conductivity square resistance of this area is greater than 5M ohms, forming a relatively non-conductive area. The selection of the compound and the control of its concentration can achieve a good vulcanization effect and improve the square resistance of the vulcanized area without significantly affecting the morphology of the nanosilver layer, so that the optical transmittance of the formed transparent conductive area is consistent with that of the transparent non-conductive area, the transmittance difference is ≤0.5%, the haze rate difference is ≤0.5%, there is no overall visual difference, and the shadow elimination effect is excellent.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The preparation method provided by the present invention can prepare a nano silver transparent conductive film with shadow elimination function efficiently, quickly and at low cost. The nano silver transparent conductive film prepared by the present invention has a clear conductive area and a non-conductive area, and the optical properties of the conductive area layer and the non-conductive area layer are highly consistent, the difference in optical transmittance and haze rate is ≤0.5%, there is no overall visual difference, and the shadow elimination and sensory effects are excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a nano silver transparent conductive film provided by an embodiment of the present invention;

[0033] Figure 2 This is an electron microscope image of the transparent conductive region layer and the transparent non-conductive region layer in Example 1 of the present invention;

[0034] Figure 3 It is an optical photograph of the transparent conductive region layer and the transparent non-conductive region layer in Example 1 of the present invention;

[0035] Description of Figure Numbers:

[0036] Transparent substrate layer-100, transparent conductive region layer-200, transparent non-conductive region layer-300, transparent protective layer-400. DETAILED DESCRIPTION

[0037] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the protection scope of the present invention.

[0038] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0039] Example 1

[0040] A method for preparing a nano silver transparent conductive film comprises the following steps:

[0041] (1) preparing a transparent conductive paste, by weight, weighing 73.5 parts of a solvent (the mass ratio of water, ethanol and ethylene glycol is 2:4:5), adding 12.3 parts of an aqueous polyurethane (solid content is 30%), and stirring for 10 minutes; then adding 14.1 parts of a nano silver wire solution (the diameter of the nano silver wire is 20 nm, the length is 23 μm, the nano silver wire content is 10 mg / mL, and the solution solvent is isopropanol), and then continuing to add 0.1 parts of a defoaming agent BYK-024 and continue stirring for 15 minutes; finally, filtering with a 200-mesh filter to remove the filter residue to prepare a transparent conductive paste;

[0042] (2) Take a PET substrate, adjust the equipment, add a transparent conductive paste, start the screen printer to print the transparent conductive paste, put the printed film into a tunnel furnace, and bake it at 145° C. for 5 minutes to form a transparent conductive layer;

[0043] (3) Take methyl mercaptan and add it to ethanol and stir for 35 minutes to prepare a methyl mercaptan solution with a concentration of 0.3 mg / mL. Adjust the equipment, add the methyl mercaptan solution, start the screen printer, print the methyl mercaptan solution on the preset non-conductive area of ​​the transparent conductive layer formed in step (2) for vulcanization treatment, put the film into a tunnel furnace after printing, and bake it at 120°C for 10 minutes to form a transparent non-conductive area layer; and the area where the methyl mercaptan solution is not printed forms a transparent conductive area layer.

[0044] (4) Prepare the protective layer ink, take Seiko ink HF GYA (N), add 10% curing agent, 5% diluent, 0.1% defoaming agent, stir manually and let stand for 10 minutes for use. Place the film formed with transparent conductive area layer and transparent non-conductive area layer in step (3) on the screen printing machine, fix and adjust the screen, pour the prepared protective layer ink, start the machine to print, put the printed film into the oven, and bake it at 150°C for 60 minutes to form a protective layer.

[0045] The nano silver transparent conductive film prepared by the above preparation method is as follows: Figure 1 As shown, the present invention comprises a transparent substrate layer (PET) 100 , a transparent conductive region layer 200 and a transparent non-conductive region layer 300 respectively disposed on the transparent substrate layer 100 , and a transparent protective layer 400 disposed on the transparent conductive region layer 200 and the transparent non-conductive region layer 300 .

[0046] After testing, the light transmittance of the transparent conductive region layer 200 is 90.3%, the haze rate is 2.05%, and the square resistance is 50-70Ω; the light transmittance of the transparent non-conductive region layer 300 is 90.1%, the haze rate is 1.99%, and the square resistance is 9-12MΩ. The square resistance greater than 5MΩ belongs to the relatively insulating area.

[0047] The nano silver transparent conductive film was observed under an electron microscope. Figure 2 The transparent conductive region layer 200 ( Figure 2 A) and the transparent non-conductive region layer 300 ( Figure 2 Electron microscope image of (B). Figure 2 It can be seen that the sulfide solution causes the contact resistance of the nanosilver to be sulfided (sulfur reacts chemically with silver), resulting in a conductive square resistance of >5M ohms, forming a non-conductive area; however, the sulfidation treatment of the sulfide solution does not have a significant effect on the morphology of the nanosilver and does not affect its optical properties. Since the difference in light transmittance and haze rate between the transparent conductive region layer 200 and the transparent non-conductive region layer 300 is small, the appearance of the two is highly consistent. Figure 3 is an optical photograph of the transparent conductive region layer 200 and the transparent non-conductive region layer 300 in Example 1 of the present invention, Figure 3 It can be seen that there is no overall visual difference between the transparent conductive region layer 200 and the transparent non-conductive region layer 300 , thus achieving the purpose of eliminating shadows.

[0048] Example 2

[0049] A method for preparing a nano silver transparent conductive film comprises the following steps:

[0050] (1) preparing a transparent conductive paste, by weight, weighing 62.5 parts of a solvent (the mass ratio of n-butanol, ethyl acetate, and propylene glycol methyl ether is 7:1:2), adding 27 parts of an aqueous polyurethane (solid content is 22%), and stirring for 15 minutes; then adding 10.4 parts of a nanosilver wire solution (the diameter of the nanosilver wire is 20 nm, the length is 23 μm, the nanosilver wire content is 10 mg / mL, and the solution solvent is isopropanol), and then continuing to add 0.1 parts of a defoaming agent BYK-024 and continue stirring for 15 minutes; finally, filtering with a 200-mesh filter to remove the filter residue to prepare a transparent conductive paste;

[0051] (2) Take a PET substrate, adjust the equipment, add a transparent conductive paste, start the screen printer to print the transparent conductive paste, put the printed film into a tunnel furnace, and bake it at 145° C. for 5 minutes to form a transparent conductive layer;

[0052] (3) Sodium thiosulfate was added to water and stirred for 35 minutes to prepare a sodium thiosulfate solution with a concentration of 1 mg / mL. The equipment was adjusted, the sodium thiosulfate solution was added, and the screen printer was started. The sodium thiosulfate solution was printed on the preset non-conductive area of ​​the transparent conductive layer formed in step (2) for vulcanization treatment. After printing, the film was placed in a tunnel furnace and baked at 120°C for 10 minutes to form a transparent non-conductive area layer; and the area where the methyl mercaptan solution was not printed formed a transparent conductive area layer.

[0053] (4) Prepare protective layer ink: take Seiko 1000 protective oil, add 35% curing agent, 10% diluent, and 0.3% defoaming agent, stir evenly by hand, and let stand for 10 minutes for use. Place the film formed with transparent conductive area layer and transparent non-conductive area layer in step (3) on the screen printing machine, fix and adjust the screen, pour the prepared protective layer ink, start the machine to print, put the printed film into the oven, and bake it at 130°C for 60 minutes to form a protective layer.

[0054] The nanosilver transparent conductive film prepared by the above preparation method includes a transparent substrate layer (PET), a transparent conductive region layer and a transparent non-conductive region layer respectively arranged on the transparent substrate layer, and a transparent protective layer arranged on the transparent conductive region layer and the transparent non-conductive region layer.

[0055] After testing, the transmittance of the transparent conductive area layer is 91.3%, the haze rate is 1.2%, and the square resistance is 50-70Ω; the transmittance of the transparent non-conductive area layer is 91.1%, the haze rate is 1.3%, and the square resistance is 10-15MΩ. The square resistance greater than 5MΩ belongs to the relatively insulating area.

[0056] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a nano silver transparent conductive film, characterized in that: The following steps are involved: (1) Weighing 1-20 parts of a nano silver wire solution, 50-95 parts of a solvent, 10-50 parts of an aqueous resin, and 0-1 parts of an additive by weight to prepare a transparent conductive paste; the diameter of the nano silver wires in the nano silver wire solution is 8-50 nm and the length is 10-30 μm; the concentration of the nano silver wire solution is 5-20 mg / mL; (2) printing the transparent conductive paste prepared in step (1) on the transparent substrate layer to form a transparent conductive layer; (3) Printing a sulfide solution on the preset non-conductive area of ​​the transparent conductive layer for sulfidation treatment to form a transparent non-conductive area layer with a square resistance greater than 5 MΩ, and forming a transparent conductive area layer with a square resistance less than 2000 Ω in the area where the sulfide solution is not printed; the sulfide solution contains 0.1-10 mg / mL of sulfide.

2. The preparation method according to claim 1, characterized in that: In step (1), the diameter of the silver nanowires in the silver nanowire solution is 10-40 nm and the length is 15-25 μm.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the concentration of the nano silver wire solution is 8-15 mg / mL.

4. The preparation method according to claim 3, characterized in that: In step (1), the nano silver wire solution uses one or more of isopropyl alcohol, ethanol, water, and propylene glycol methyl ether as solvent.

5. The preparation method according to claim 1 or 2, characterized in that: In step (1), the solvent is selected from at least one of water, ethanol, ethylene glycol, n-butanol, ethyl acetate, propylene glycol methyl ether, glycerol, and diformate; and the water-based resin is selected from at least one of water-based polyurethane, water-based acrylic acid, carboxymethyl cellulose, water-based epoxy resin, amino resin, and polyethylene oxide.

6. The preparation method according to claim 5, characterized in that: In step (1), 5-15 parts of nano silver wire solution, 60-80 parts of solvent, 10-30 parts of water-based resin, and 0-1 part of auxiliary agent are weighed in parts by weight to prepare a transparent conductive paste.

7. The preparation method according to claim 1 or 2, characterized in that: In step (2), the transparent substrate layer includes one of polyethylene terephthalate, glass, polyimide, acrylic, and polycarbonate.

8. The preparation method according to claim 1 or 2, characterized in that: In step (3), the sulfide is selected from at least one of sodium sulfide, sodium thiosulfate, ethionine, cysteine, mercaptoformic acid, and thioethanol.

9. The preparation method according to claim 8, characterized in that: In step (3), the sulfide solution uses one or more of water, ethanol and ether as solvent.

10. A nano silver transparent conductive film with shadow elimination function, characterized in that: The nanosilver transparent conductive film is prepared by the preparation method described in any one of claims 1 to 9, wherein the transmittance difference between the transparent conductive region layer and the transparent non-conductive region layer is ≤0.5%, and the haze difference is ≤0.5%.

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