Polyethylene composite for flexible display screens

Abstract

The present application provides a composite material, a flexible screen and a transparent substrate comprising the composite material, and a method for manufacturing a composite material of a foldable material. The composite material comprises an ultra-high molecular weight polyethylene (UHMWPE) and a hard coating material, a portion of the hard coating material penetrating into the UHMWPE. The UHMWPE has a highly porous structure of polyethylene, and the hard coating material is in a liquid form. The UHMWPE can be formed into a layer, another portion of the hard coating material being deposited on the layer. The UHMWPE layer has a thickness less than 2 µm, a tensile strength greater than 500 MPa, and the composite material has a thickness less than 5 µm, a tensile strength greater than 100 MPa. Furthermore, the entire composite material is creaseless after more than 200,000 folds.

Description

[0001] Cross-reference to related applications

[0002] This application requires a U.S. application sequence number filed on March 21, 2022.

[0003] The rights of 63 / 322,213, the entire contents of which are incorporated herein by reference, including any tables, figures or figures. Technical Field

[0004] This application relates to composite materials for display screens and optics. More specifically, this application relates to a composite material comprising ultra-high molecular weight polyethylene (UHMWPE) and a rigid coating material that can be used in flexible display screens / optics, a method for manufacturing the composite material, and a flexible screen for a foldable or rollable display made from the composite material. Background Technology

[0005] In recent years, foldable screens, as a next-generation display technology, have received widespread attention because they resolve the conflict between portability and display area requirements. One of the key issues hindering the widespread adoption of foldable displays lies in the development of foldable substrates and protective screens. Among all materials, flexible transparent plastic film is considered the most promising alternative to the tempered glass currently commonly used in foldable displays.

[0006] Tempered glass is the preferred choice for covering windows of rigid displays due to its excellent scratch resistance and overall screen protection. Theoretically, a possible way to make glass flexible is to reduce its thickness; however, thinning the glass can raise significant concerns about excessive brittleness. In reality, a potential alternative to thick tempered glass is a combination of a plastic film and a flexible, hard coating to provide glass-like hardness with scratch resistance, excellent transparency, and polymer-like flexibility to withstand high deformation without damage.

[0007] Unfortunately, the most advanced technologies developed for producing foldable protective screens / substrates cannot fully meet the requirements for high transparency, excellent scratch resistance, no creases, and good mechanical stability.

[0008] For smartphone screen covers that protect the display screen, both resilience and flexibility are required. Colorless polyimide (CPI) and polyethylene terephthalate (PET) films are two main materials used in the flexible display industry. However, a major problem with CPI or PET films is that creases appear when the film is folded multiple times. Summary of the Invention

[0009] There is still a need in this field for improved design and technology of composite materials, as well as methods for manufacturing flexible display screens.

[0010] According to an embodiment of this application, a composite material for manufacturing foldable materials is provided, comprising ultra-high molecular weight polyethylene (UHMWPE) and a rigid coating material, a first portion of which permeates into the UHMWPE. The UHMWPE has a highly porous structure characteristic of polyethylene. The rigid coating material is in liquid form. Furthermore, the UHMWPE is formed as a layer, on which a second portion of the rigid coating material is deposited. The thickness of the UHMWPE layer is less than 2 μm. The tensile strength of the UHMWPE layer is greater than 500 MPa.

[0011] In some embodiments of this application, a flexible screen for manufacturing a foldable or rollable display is provided, comprising: the aforementioned composite material, which is configured such that the flexible screen exhibits a scratch resistance hardness greater than 5H when scratched by a hard object.

[0012] In some embodiments of this application, a flexible screen for manufacturing a foldable or rollable display is provided, comprising: the aforementioned composite material, configured such that when light propagates through the flexible screen, the light transmittance of visible light is greater than 90%.

[0013] In some embodiments of this application, a transparent substrate for optical devices is provided, comprising the aforementioned composite material, which is configured such that the transparent substrate exhibits a scratch resistance hardness greater than 5H when scratched by a hard object.

[0014] In some embodiments of this application, a transparent substrate for an optical device is provided, comprising the aforementioned composite material, which is configured such that when light propagates through the transparent substrate, the transmittance of visible light is greater than 90%.

[0015] In another embodiment of this application, a method for manufacturing a composite material for use in the manufacture of a foldable or rollable display is provided. The method includes preparing a nanoporous ultra-high molecular weight polyethylene (UHMWPE) substrate; and depositing a hard coating material on the upper surface of the UHMWPE substrate such that a portion of the hard coating material penetrates into the internal structure of the UHMWPE substrate. The UHMWPE substrate has a highly porous structure of polyethylene. The hard coating material is in liquid form. The hard coating consists of acrylate oligomers and amorphous silica. Furthermore, the solvent for the coating can be a wide range of organic solvents, including but not limited to acetone, acetonitrile, methyl ethyl ketone, or propylene glycol methyl ether. The hard coating liquid can penetrate into the UHMWPE by spin coating, dip coating, blade coating, and rod coating. Furthermore, the UHMWPE substrate is formed as a layer on which the hard coating material is deposited. The thickness of the UHMWPE layer is less than 2 μm. The tensile strength of the UHMWPE layer is greater than 500 MPa. The total thickness of the composite layer is less than 5 μm. The tensile strength of the composite material is greater than 100 MPa. The entire layer of the composite material has no creases after N folds, where N is an integer greater than 200,000. Attached Figure Description

[0016] Figure 1 The embodiment of the present application shows a highly porous structure formed by interlacing UHMWPE nanofibers with a diameter of 10 nm to 40 nm, wherein each fiber contains highly ordered extended chain fiber crystals, which include folded chain sheet crystals.

[0017] Figure 2 A schematic diagram illustrating the structure of a composite material comprising a UHMWPE membrane and a hard coating according to an embodiment of this application is provided.

[0018] Figure 3 The results of light transmittance tests on a composite material comprising a transparent UHMWPE film and a hard coating according to an embodiment of this application are shown.

[0019] Figure 4 The results of tensile stress-strain tests on a composite material comprising a transparent UHMWPE film and a rigid coating according to an embodiment of this application are shown.

[0020] Figure 5 A scanning electron microscope (SEM) image of a cross section of a composite material comprising a transparent UHMWPE film and a hard coating according to an embodiment of this application is shown. Detailed Implementation

[0021] The embodiments of this application relate to an ultrathin polymer solid composite material comprising a layer of ultra-high molecular weight polyethylene and a layer of hard coating material, and a method for producing an ultrathin polymer solid composite material with excellent scratch resistance, high transparency and good mechanical strength for use in manufacturing crease-free foldable display screens.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application. The term “and / or” as used herein includes any and all combinations of one or more of the associated enumerated items. Unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” as used herein are intended to include both plural and singular forms. It will also be understood that, when used in this specification, the terms “comprising” and / or “including” mean the presence of the stated features, steps, operations, elements, and / or components, but do not imply the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0023] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the relevant technical context and in the context of this disclosure, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0024] When the term “about” is used in this document, it is understood in conjunction with a numerical value to mean that the value can be in the range of 90% to 110% of the value, that is, the value can be + / - 10% of the value. For example, “about 1 kg” means 0.90 kg to 1.1 kg.

[0025] In describing this application, it will be understood that numerous techniques and steps are disclosed. Each of these techniques and steps has its own individual benefits and may be used in combination with one or more other disclosed techniques, or in some cases with all of the other disclosed techniques. Therefore, for clarity, this description will avoid unnecessarily repeating every possible combination of the individual steps. However, upon reading the specification and claims, it should be understood that such combinations are entirely within the scope of this application and the claims.

[0026] refer to Figure 1 This paper illustrates a highly porous structure of UHMWPE. This highly porous structure consists of interwoven UHMWPE nanofibers with diameters ranging from 10 nm to 40 nm, each fiber containing highly ordered extended chain fiber crystals, including folded chain lamellar crystals. The porosity is greater than 50%.

[0027] refer to Figure 2The structure of an ultrathin polymer solid composite material is shown. This composite material comprises a layer of ultra-high molecular weight polyethylene (UHMWPE) and a layer of rigid coating material, wherein the UHMWPE layer acts as a support material, and the rigid coating material permeates into the UHMWPE layer, thereby creating a flexible screen cover. Due to the reduced overall thickness, the transmittance of visible light passing through the composite material can be significantly increased to a level greater than 90%, such as... Figure 3 As shown.

[0028] Furthermore, due to the highly porous structure of polyethylene, the nanofibers in the UHMWPE layer, when infiltrated with a rigid coating material, create strong van der Waals forces by providing a high specific surface area for bonding with the rigid coating. As a result, the adhesion between the UHMWPE layer and the rigid coating material is significantly enhanced due to the increased contact area, and excellent rigidity and hardness can be achieved. Figure 5 A scanning electron microscope (SEM) image of a cross section of a composite material comprising a transparent UHMWPE film and a hard coating material is shown.

[0029] In one embodiment of this application, a method is provided for producing an ultrathin polymer solid composite material for manufacturing flexible display screens, the flexible display screens being transparent, foldable / rollable, and scratch-resistant. The method includes a first step of preparing a nanoporous UHMWPE substrate with a thickness less than 2 μm and a tensile strength greater than 500 MPa, and a second step of depositing a liquid hard coating material on the upper surface of the UHMWPE substrate by spin coating, rod coating, or dip coating, thereby allowing the liquid hard coating material to penetrate into the internal structure of the UHMWPE substrate.

[0030] Ultrathin polymer solid composites offer many advantages. For example... Figure 3 As shown, for visible light, a transmittance greater than 90% is obtained at 500 nm. Furthermore, the composite material exhibits excellent scratch resistance (>5H pencil test) and demonstrates good mechanical stability after the coating reaction (e.g., tensile strength greater than 100 MPa, such as...). Figure 4 (As shown). Furthermore, the composite material shows no creases after many folds (e.g., 200,000).

[0031] Furthermore, the UHMWPE layer, containing a linear flexible polymer material with extremely low molecular chain steric hindrance, exhibits no fatigue effect after repeated folding and provides excellent mechanical properties and transparency. When the UHMWPE layer is infiltrated with a hard coating material, excellent rigidity and hardness can be achieved.

[0032] All patents, patent applications, provisional applications and publications referenced or cited herein are incorporated herein in their entirety, including all figures and tables, and to a certain extent, they do not contradict the explicit teachings of this specification.

[0033] It should be understood that the embodiments and implementations described herein are for illustrative purposes only and will suggest to those skilled in the art various modifications or changes to the embodiments and implementations described herein, and such modifications or changes will be included within the spirit and scope of this application and the appended claims. Furthermore, any element or limitation of any invention or implementation thereof disclosed herein may be combined with any and / or all other elements or limitations disclosed herein (alone or in any combination) or any other invention or implementation thereof, and all such combinations are within the scope of this application, but are not limited thereto.

Claims

1. A composite material for manufacturing foldable materials, said composite material comprising: Ultra-high molecular weight polyethylene (UHMWPE) having a highly porous structure composed of interwoven UHMWPE nanofibers with a diameter of 10 nm to 40 nm, wherein each fiber comprises highly ordered extended chain fiber crystals, the extended chain fiber crystals including folded chain sheet crystals; and A hard coating material, wherein the hard coating is composed of acrylate oligomers and amorphous silica; The first portion of the hard coating material penetrates into the UHMWPE, and The entire layer of the composite material is crease-free after N folds, where N is an integer greater than 200,000.

2. The composite material according to claim 1, wherein the hard coating material is deposited in liquid form.

3. The composite material according to claim 1, wherein the UHMWPE is formed as a layer, and a second portion of the hard coating material is deposited on the layer.

4. The composite material according to claim 3, wherein the thickness of the UHMWPE layer is less than 2 µm.

5. The composite material according to claim 3, wherein the tensile strength of the UHMWPE layer is greater than 500 MPa.

6. A flexible screen for manufacturing a foldable or rollable display, the flexible screen comprising: The composite material according to claim 1; The composite material is configured such that when light propagates through the flexible screen, the light transmittance of visible light is greater than 90%.

7. A transparent substrate for use in optical devices, the transparent substrate comprising: The composite material according to claim 1; The composite material is configured such that when light propagates through the transparent substrate, the light transmittance of visible light is greater than 90%.

8. A method for manufacturing a composite material for producing a foldable or rollable display, the method comprising: Prepare a nanoporous ultra-high molecular weight polyethylene (UHMWPE) substrate. The UHMWPE substrate has a highly porous polyethylene structure composed of interwoven UHMWPE nanofibers with a diameter of 10 nm to 40 nm. Each fiber contains highly ordered extended chain fiber crystals, including folded chain sheet crystals. A hard coating material is deposited on the upper surface of the UHMWPE substrate, such that a portion of the hard coating material penetrates into the internal structure of the UHMWPE substrate. The hard coating is composed of acrylate oligomers and amorphous silica, and The entire layer of the composite material is crease-free after N folds, where N is an integer greater than 200,000.

9. The method of claim 8, wherein the hard coating material is in liquid form.

10. The method of claim 8, wherein the UHMWPE substrate is formed as a layer and the hard coating material is deposited on the layer.

11. The method of claim 10, wherein the thickness of the UHMWPE layer is less than 2 µm.

12. The method of claim 10, wherein the tensile strength of the UHMWPE layer is greater than 500 MPa.

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