Light shielding conductive sheet and electronic device having the same

Abstract

The utility model provides an electrically-conductive light-shielding sheet and an electronic device having the same. The electrically-conductive light-shielding sheet includes at least one light-shielding layer and at least one electrically-conductive layer, wherein the light-shielding layer and the electrically-conductive layer are stacked along the thickness direction of the electrically-conductive light-shielding sheet. The electrically-conductive light-shielding sheet is formed by stacking the light-shielding layer and the electrically-conductive layer along the thickness direction, and the electrically-conductive property and the light-shielding property are separated into two independent layers. This layered structure allows the function of each layer to be optimized independently, for example, the light-shielding degree of the light-shielding layer or the conductivity of the electrically-conductive layer can be adjusted as needed without affecting each other, while avoiding potential electrochemical or physicochemical interference between the two fillers, providing higher design freedom.

Description

Technical Field

[0001] This utility model relates to the field of materials technology, and in particular to a light-shielding conductive sheet and an electronic device having the same. Background Technology

[0002] With the continuous development of consumer electronics, users' aesthetic requirements for products are increasing, especially in the field of display devices such as smartphones and tablets, where the "all-black" design has become a mainstream trend. "All-black" refers to a device where, when the screen is off, the screen area presents a deep, uniform pure black effect, blending seamlessly with the bezel. To achieve this effect, it is necessary to effectively conceal non-black components such as internal metal wiring and light-emitting devices.

[0003] Currently, the industry commonly uses light-shielding conductive inks or adhesives to achieve the above functions. However, existing technical solutions mostly use carbon black or carbon nanotubes as fillers for both conductivity and light shielding. Although these materials have a certain light-shielding effect, they are also conductive, causing the conductivity and light-shielding properties of the ink to be coupled together, making it difficult to independently and precisely control them.

[0004] Therefore, the industry urgently needs a new type of light-shielding conductive sheet and electronic devices incorporating it. Utility Model Content

[0005] The purpose of this invention is to provide a light-shielding conductive sheet and an electronic device having the same.

[0006] A light-shielding conductive sheet includes: at least one light-shielding layer and at least one conductive layer; wherein the light-shielding layer and the conductive layer are stacked along the thickness direction of the light-shielding conductive sheet.

[0007] In some embodiments, the light-shielding layer and the conductive layer are stacked sequentially.

[0008] In some embodiments, both the light-shielding layer and the conductive layer are two or more layers, and the light-shielding layer and the conductive layer are alternately stacked.

[0009] In some embodiments, the conductive layers are independent of each other; or the conductive layers are electrically connected by an electrical connector that passes through the light-shielding layer, or the electrical connector is located outside the light-shielding layer.

[0010] In some embodiments, the light-shielding layer is located on the light-incident side or the back-light side of the conductive layer.

[0011] In some embodiments, the thickness of the light-shielding layer is 15 μm to 25 μm; and / or the thickness of the conductive layer is 60 μm to 80 μm.

[0012] In some embodiments, the light-shielding layer is a bismuth sulfide light-shielding layer.

[0013] In some embodiments, the light-shielding layer is a urchin-shaped bismuth sulfide light-shielding layer.

[0014] In some embodiments, the conductive layer is a metal nanowire conductive layer.

[0015] In some embodiments, the metal nanowires are silver nanowires or aluminum nanowires, the diameter of the metal nanowires is 10 to 100 nm, and / or the length of the metal nanowires is 5 μm to 50 μm.

[0016] An electronic device comprising any of the aforementioned light-shielding conductive sheets.

[0017] Compared with existing technologies, the advantages of this invention are as follows: by stacking a light-shielding layer and a conductive layer along the thickness direction to form a light-shielding and conductive sheet, the conductivity and light-shielding functions are separated into two independent layers. This layered structure allows for independent optimization of the function of each layer. For example, the light-shielding degree of the light-shielding layer or the conductivity of the conductive layer can be adjusted as needed without affecting each other. At the same time, it can also avoid potential electrochemical or physicochemical interference between the two fillers, providing greater design freedom. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0019] Figure 1 This is a schematic diagram of the structure of a light-shielding conductive sheet according to the present invention.

[0020] Figure 2 This is a schematic diagram of another type of light-shielding conductive sheet according to the present invention.

[0021] Figure 3 This is a schematic diagram of another type of light-shielding conductive sheet according to the present invention.

[0022] Figure 4 This is a schematic diagram of another type of light-shielding conductive sheet according to the present invention.

[0023] In the diagram: 100 - light-shielding conductive sheet; 10 - light-shielding layer; 20 - conductive layer; 30 - electrical connector. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0025] To address the issues of inaccurate control of conductivity and light-shielding properties in existing conductive inks, and their high absorption of ultraviolet light affecting ink curing, this invention adopts a design concept that separates conductivity and light-shielding functions, providing a light-shielding conductive ink that combines high light-shielding and high conductivity.

[0026] Please refer to Figures 1 to 4 As shown, this utility model provides a light-shielding conductive sheet 100, which includes at least one light-shielding layer 10 and at least one conductive layer 20. The light-shielding layer 10 and the conductive layer 20 are stacked along the thickness direction of the light-shielding conductive sheet 100. This layered structure allows for independent optimization of the function of each layer. For example, the light-shielding degree of the light-shielding layer or the conductivity of the conductive layer can be adjusted as needed without affecting each other. At the same time, it can also avoid potential electrochemical or physicochemical interference between the two fillers, providing greater design freedom.

[0027] In some implementations, such as Figures 1 to 3 As shown, the light-shielding layer 10 and the conductive layer 20 are stacked sequentially, which is simple to manufacture and can form a light-shielding and conductive sheet with light-shielding and conductive properties.

[0028] In other implementations, such as Figure 4 As shown, both the light-shielding layer 10 and the conductive layer 20 are two or more layers. When the light-shielding layer 10 and the conductive layer 20 are multi-layered structures, they are alternately arranged to form a light-shielding and conductive sheet with light-shielding and conductive properties.

[0029] In one embodiment, in an alternating configuration, each conductive layer 20 can be independent of each other, integrating various conductivity requirements.

[0030] In another embodiment, in an alternating configuration, the conductive layers 20 can be electrically connected as a whole. Specifically, the conductive layers 20 are electrically connected by electrical connectors 30, which pass through (penetrate) the light-shielding layer 20, or the electrical connectors 30 are located on the outside of the light-shielding layer 10.

[0031] Based on any of the above arrangements, the light-shielding layer 10 is located on the light-incident side or the back-light side of the conductive layer 20. It is understood that "light-incident side" and "back-light side" are relative to the application location of the sheet in an electronic device (such as a display screen). For example, when it is necessary to protect the conductive layer from external light or environmental influences, the light-shielding layer can be placed on the light-incident side. This flexible stacking sequence can be adjusted according to specific optical path or circuit design requirements to achieve optimal optical or electrical performance.

[0032] In one embodiment, the thickness of the light-shielding layer 10 is 15 μm to 25 μm, which is sufficient to ensure that the light-shielding layer achieves the target optical density, such as OD > 4.

[0033] The conductive layer 20 has a thickness of 60 μm to 80 μm, which ensures that the conductive layer forms a stable and effective conductive network and achieves the target sheet resistance, such as <10 Ω / sq.

[0034] The thickness of the light-shielding layer 10 is matched with the thickness of the conductive layer 20, so that the light-shielding conductive sheet 100 has both conductivity and light-shielding properties, and achieves a good balance between conductivity and light-shielding properties.

[0035] In this invention, the light-shielding layer 10 is a bismuth sulfide light-shielding layer, preferably a sea urchin-shaped bismuth sulfide light-shielding layer. Bismuth sulfide material has good light-shielding properties, which can improve the light-shielding performance of the light-shielding layer 10.

[0036] Specifically, the light-shielding layer 10 includes a first photocurable resin and urchin-shaped bismuth sulfide dispersed in the first photocurable resin.

[0037] The first type of UV-curable resin is selected from at least one of polyurethane acrylate, epoxy acrylate, polyester acrylate, and acrylate oligomers. Using this type of UV-curable resin allows for rapid UV curing, significantly shortening the production cycle compared to thermosetting systems, achieving instant curing at room temperature, and making it suitable for substrates that are not heat-resistant.

[0038] Sea urchin-like bismuth sulfide refers to bismuth sulfide particles that exhibit a spherical or hemispherical three-dimensional structure resembling a sea urchin, formed by the radial growth of nanowires or nanorods from the center outwards.

[0039] The average diameter of the urchin-shaped bismuth sulfide nanowires or nanorods ranges from 10 nm to 50 nm, and the average length ranges from 100 nm to 500 nm, resulting in an overall specific surface area greater than 50 m² / g. This unique microstructure gives it an extremely high specific surface area and a complex optical path, causing incident light to undergo multiple scattering and absorption processes within it—a phenomenon known as the light-trapping effect. This allows for excellent light-blocking effects with relatively low addition amounts.

[0040] In a preferred embodiment, the content of urchin-shaped bismuth sulfide is 0.1% to 5% by weight of the total light-blocking layer, with the balance being the first photocurable resin. If the content is below 0.1%, the ideal optical density (OD value) may not be achieved, resulting in insufficient light-blocking effect. If the content is above 5%, it may lead to excessive ink viscosity and poor flowability. Excessive inorganic filler may also cause the cured coating to become brittle, affecting mechanical properties. This content range ensures excellent "one-piece black" light-blocking effect while avoiding negative impacts on the composition's leveling properties, storage stability, and curing depth due to excessive filler content.

[0041] Bismuth sulfide, as a semiconductor material, has light absorption characteristics determined by its band gap. To further improve UV curing efficiency, in a particularly preferred embodiment, the urchin-like bismuth sulfide is bismuth sulfide that has undergone elemental doping or surface oxidation treatment. The doping elements are cations of Zn, Ti, and Al. Elemental doping or the formation of a thin oxide layer on the surface can effectively modulate its semiconductor band structure, broaden its band gap, and cause a blue shift in the absorption edge of its intrinsic absorption band. This significantly reduces its absorption of UV light in commonly used curing wavelengths (such as 365 nm), further enhancing the UV curing performance of the entire composition.

[0042] The conductive layer 20 is a metal nanowire conductive layer. The metal nanowires have a one-dimensional nanostructure with a diameter of 10 nm to 100 nm and a length of 5 μm to 50 μm, exhibiting an extremely high aspect ratio. This characteristic allows the metal nanowires to interconnect in the resin matrix with relatively low addition amounts, forming an effective conductive network.

[0043] In a preferred embodiment, the metal content, based on the total weight of the conductive layer, is 0.1% to 10%, with the remainder being a second photocurable resin. If the content is below 0.1%, the metal nanowires will struggle to form a continuous and effective conductive path, resulting in substandard conductivity. If the content is above 10%, it will not only significantly increase costs but also lead to excessively high ink viscosity, affecting coating processability, and excessive filler may also adversely affect curing. This content range effectively balances conductivity, ink viscosity, and production costs, ensuring that the final cured product achieves the designed conductivity.

[0044] The present invention preferably employs metal nanowires with low absorption in the ultraviolet region, such as at least one or a combination of silver nanowires and / or aluminum nanowires.

[0045] Silver nanowires, as excellent conductive fillers, have extremely low absorption rates in the ultraviolet light region (such as the 365nm and 395nm bands), which is beneficial for the curing of light-shielding conductive inks under UV light.

[0046] Aluminum has a plasmon resonance peak at ~82 nm (far ultraviolet region). Therefore, aluminum nanostructures exhibit low absorption across the entire ultraviolet band (UVA, UVB, UVC). Specifically, the conductive layer 20 comprises metal nanowires dispersed in a second photocurable resin.

[0047] The second UV-curable resin is selected from at least one of polyurethane acrylate, epoxy acrylate, polyester acrylate, and acrylate oligomers. Using this type of UV-curable resin allows for rapid UV curing, significantly shortening the production cycle compared to thermosetting systems, achieving instant curing at room temperature, and making it suitable for substrates that are not heat-resistant.

[0048] The first photocurable resin is the same as the second photocurable resin. The two film layers have the same substrate, resulting in high compatibility.

[0049] In one embodiment, the first UV-curable resin and the second UV-curable resin are different. A resin with higher hardness can be selected for the light-shielding layer to improve scratch resistance, while a resin with better flexibility can be selected for the conductive layer to accommodate bending requirements. This provides process flexibility for the production of the sheet material.

[0050] The combination of low UV absorption metal rice wire and the second UV-curable resin not only makes the conductive layer conductive, but also significantly reduces the absorption of UV light required for curing by the entire conductive layer, improving the UV curing efficiency. This allows the light-shielding conductive ink to cure completely in a shorter time, thus perfectly solving the technical pain point of difficult UV curing in carbon black systems.

[0051] Of course, metal nanowires can also be replaced with other metal nanowires with better conductivity, such as gold nanowires or copper nanowires, so that the conductive layer has good conductivity.

[0052] This invention also provides a light-shielding conductive ink for preparing the aforementioned light-shielding conductive sheet. The light-shielding conductive ink comprises a metal nanowire dispersion and a sea urchin-shaped bismuth sulfide dispersion. The metal nanowire dispersion comprises a metal and a first photocurable resin. The sea urchin-shaped bismuth sulfide dispersion comprises sea urchin-shaped bismuth sulfide and a second photocurable resin.

[0053] The first and second photocurable resins are described above, and will not be repeated here.

[0054] The metal nanowires are selected from metal rice wire with low UV absorption. This not only gives the metal nanowire dispersion the properties of conductivity, high light shielding, and high infrared reflection, but also significantly reduces the absorption of UV light required for curing by the entire metal nanowire dispersion, thereby improving the photocuring efficiency. This allows the metal nanowire dispersion to be completely cured in a shorter time, thus perfectly solving the technical pain point of UV curing difficulties in carbon black systems.

[0055] Of course, metal nanowires can also be replaced with other metal nanowires with better conductivity, such as gold nanowires and copper nanowires, to obtain light-shielding conductive sheets with excellent conductivity and good light-shielding properties.

[0056] The metal nanowire content, based on the total weight of the metal nanowire dispersion, is 0.1% to 10%, with the balance being the first photocurable resin. If the content is below 0.1%, the metal nanowires will struggle to form a continuous and effective conductive pathway, resulting in substandard conductivity. If the content is above 10%, it will not only significantly increase costs but also lead to excessively high viscosity of the metal nanowire dispersion, affecting coating processability. Furthermore, excessive filler may also adversely affect curing. This content range effectively balances conductivity, the viscosity of the metal nanowire dispersion, and production costs, ensuring that the final cured product achieves the designed conductivity.

[0057] As described above, urchin-shaped bismuth sulfide is an excellent light-shielding material with a good overall black effect; it can also reflect infrared rays, reducing heat radiation; and its absorption of ultraviolet light is much lower than that of carbon black, which is beneficial for the curing of light-shielding conductive inks under UV light.

[0058] The content of the bismuth sulfide dispersion in the sea urchin-like form is 0.1% to 5% by weight, with the balance being a second photocurable resin. If the content is below 0.1%, the ideal optical density (OD value) may not be achieved, resulting in insufficient light-blocking effect. If the content is above 5%, the viscosity of the bismuth sulfide dispersion may be too high, leading to poor flowability. Excessive inorganic filler may also cause the cured coating to become brittle, affecting mechanical properties. This content range ensures excellent "one-piece black" light-blocking effect while avoiding negative impacts on the leveling properties, storage stability, and curing depth of the composition due to excessive filler content.

[0059] In addition, the metal nanowire dispersion and the urchin-shaped bismuth sulfide dispersion also include additives. These additives are selected from at least one of monomer and photoinitiator combinations, leveling agents, defoamers, dispersants, stabilizers, UV absorbers, and solvents. The addition of these additives can significantly improve the overall performance of the light-shielding conductive ink.

[0060] Monomers, acting as reactive diluents, can adjust viscosity. Monomers include, but are not limited to, monofunctional acrylate monomers, difunctional acrylate monomers, trifunctional acrylate monomers, and polyfunctional acrylate monomers. The monomer content is 1% to 10% of the total weight of the metal nanowire dispersion or the urchin-like bismuth sulfide dispersion.

[0061] The role of photoinitiators is to absorb light energy of a specific wavelength, undergo a chemical reaction, and produce active species (such as free radicals or cations), thereby initiating cross-linking polymerization of monomer oligomers and rapidly transforming the system from a liquid state to a solid state.

[0062] The photoinitiator is selected from at least one of acylphosphine oxides, macromolecular initiators, α-amino ketones, and photosensitizers. Acylphosphine oxides include, but are not limited to, TPO-L (sensitive wavelength 395 nm), BAPO (sensitive wavelength 405 nm), and TPO (sensitive wavelength 365 nm-385 nm). Macromolecular initiators include, but are not limited to, Omnirad 127 (sensitive wavelength 365 nm-385 nm) and Omnirad 2100 (sensitive wavelength 395 nm). α-amino ketones include, but are not limited to, Omnirad 369. Photosensitizers include, but are not limited to, ITX. Preferably, the use of α-amino ketones with ITX can extend the absorption range.

[0063] The proportion of photocuring agent is related to the ratio of resin and monomer, and can be 1% to 10% of the total weight of resin and monomer.

[0064] Leveling agents reduce surface tension, resulting in a smooth coating. Leveling agents include, but are not limited to, silicone leveling agents, acrylate leveling agents, fluorinated leveling agents, etc. The leveling agent content is 0.01% to 5% by weight of the total weight of the metal nanowire dispersion or the urchin-shaped bismuth sulfide dispersion.

[0065] Defoamers can eliminate air bubble defects during the curing process. Defoamers include, but are not limited to, silicone-based defoamers, mineral oil-based defoamers, polyether-based defoamers, etc. The content of the defoamer is 0.01% to 5% based on the total weight of the metal nanowire dispersion or the urchin-shaped bismuth sulfide dispersion.

[0066] Dispersants contribute to the stable dispersion of metal nanowires and fillers such as the urchin-shaped bismuth sulfide. Dispersants include, but are not limited to, polyvinylpyrrolidone, silane coupling agents, oleic acid, stearic acid, etc. The content of the dispersant is 0.01% to 5% based on the total weight of the metal nanowire dispersion or the urchin-shaped bismuth sulfide dispersion.

[0067] Furthermore, this invention employs a high-shear dispersion device to improve dispersibility. This dispersion device includes, but is not limited to, a three-roll mill and a bead mill. By combining the dispersant with the dispersion device, a uniformly dispersed and stable dispersion can be obtained.

[0068] Stabilizers can improve the long-term weather resistance and reliability of products. Stabilizers include, but are not limited to, antioxidants, hindered amine light stabilizers, ultraviolet absorbers, thiols, etc. The content of stabilizers is 0.01% to 5% based on the total weight of the metal nanowire dispersion or the urchin-shaped bismuth sulfide dispersion.

[0069] Solvents are used to dissolve or disperse the above components, ensuring uniform mixing and improving film quality. Solvents include, but are not limited to, ethyl acetate, propylene glycol methyl ether, diacetone alcohol, diethylene glycol methyl ether, butyl acetate, etc. The amount of solvent used should be sufficient to decompose the above components; the solvent content should be 0% to 20% based on the total weight of the metal nanowire dispersion or the urchin-shaped bismuth sulfide dispersion.

[0070] This invention also provides a method for preparing a light-shielding conductive sheet, wherein a light-shielding layer 10 and a conductive layer 20 are formed by using a urchin-shaped bismuth sulfide dispersion and a metal nanowire dispersion, respectively.

[0071] The method for preparing a light-shielding conductive sheet includes the following steps: forming a light-shielding film layer by dispersing a bismuth sulfide solution in the shape of a sea urchin, and curing the light-shielding film layer to form a light-shielding layer; and forming a conductive film layer by dispersing a metal nanowire solution, and curing the conductive film layer to form a conductive layer.

[0072] In one specific embodiment, a substrate is used as the substrate. First, a light-shielding film layer is formed by a dispersion of urchin-shaped bismuth sulfide, and after UV curing, a light-shielding layer 10 is formed. On the light-shielding layer 10, a conductive film layer is formed by a dispersion of metal nanowires, and after UV curing, a conductive layer 20 is formed.

[0073] In one specific embodiment, a substrate is used as the substrate. First, a conductive coating is formed by dispersing metal nanowires, and after UV curing, a conductive layer 20 is formed. On the cured conductive coating 20, a light-shielding film layer is formed by dispersing urchin-shaped bismuth sulfide, and after UV curing, a light-shielding layer 10 is formed.

[0074] These two methods correspond to two process sequences: preparing the light-shielding layer first and preparing the conductive layer first, respectively. Both are clear and feasible industrial production solutions.

[0075] The substrate can be a plastic substrate, a glass substrate, or a release film. The light-shielding conductive sheet is molded onto the release film, making it easy to peel off and apply to the desired product; the application scenarios are not limited by the substrate.

[0076] The film can be prepared by methods such as, but not limited to, blade coating, spin coating, slot coating, and screen printing.

[0077] By irradiating the liquid ink under a UV lamp with a specific energy, such as 800 mJ / cm² to 2000 mJ / cm², for 30 to 90 seconds, the liquid ink can be rapidly transformed into a light-shielding or conductive layer with stable mechanical properties (such as hardness and adhesion), electrical properties, and optical properties. The resulting light-shielding and conductive sheet integrates conductivity and light-shielding functions and can be directly applied to electronic devices.

[0078] This utility model also provides an electronic device, which includes any of the above-mentioned light-shielding conductive sheets 100. The electronic device may be a smartphone, a display, a wearable device, etc.

[0079] Applying the light-shielding conductive sheet 100 of this utility model to areas requiring light-shielding and conductivity, such as the screen bezel of electronic devices, the periphery of camera modules, or flexible circuit boards, can effectively shield internal circuits and components, achieving a pure "all-in-one black" appearance. At the same time, it provides reliable grounding or electromagnetic shielding functions, and helps with heat management, improving the overall quality and performance of the equipment.

[0080] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A light-shielding conductive sheet, characterized in that, include: At least one light-blocking layer; as well as At least one conductive layer; Wherein, the light-shielding layer and the conductive layer are stacked along the thickness direction of the light-shielding conductive sheet; both the light-shielding layer and the conductive layer are two or more layers, and the light-shielding layer and the conductive layer are stacked alternately; the light-shielding layer and the conductive layer are stacked alternately, and each conductive layer is independent of the others; or, the light-shielding layer and the conductive layer are stacked alternately, and each conductive layer is electrically connected through an electrical connector, the electrical connector passing through the light-shielding layer, or the electrical connector being located outside the light-shielding layer.

2. The light-shielding conductive sheet according to claim 1, characterized in that, The light-shielding layer is located on the light-incident side or the back-light side of the conductive layer.

3. The light-shielding conductive sheet according to claim 1, characterized in that, The thickness of the light-shielding layer is 15 μm to 25 μm; and / or the thickness of the conductive layer is 60 μm to 80 μm.

4. The light-shielding conductive sheet according to claim 1, characterized in that, The light-shielding layer is a bismuth sulfide light-shielding layer.

5. The light-shielding conductive sheet according to claim 1, characterized in that, The light-shielding layer is a bismuth sulfide light-shielding layer in the shape of a sea urchin.

6. The light-shielding conductive sheet according to claim 1, characterized in that, The conductive layer is a metal nanowire conductive layer.

7. The light-shielding conductive sheet according to claim 1, characterized in that, The metal nanowires are silver nanowires or aluminum nanowires, the diameter of the metal nanowires is 10 to 100 nm, and / or the length of the metal nanowires is 5 μm to 50 μm.

8. An electronic device, characterized in that, Includes the light-shielding conductive sheet as described in any one of claims 1 to 7.

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