CN-116790016-B - Polyethylene composite material for flexible display screen

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 Ultra High Molecular Weight Polyethylene (UHMWPE) and a hard coating material, a portion of which penetrates into the UHMWPE. The UHMWPE has a highly porous structure of polyethylene and the hard coating material is in liquid form. The UHMWPE may be formed as a layer on which another portion of the hard coating material is deposited. The UHMWPE layer has a thickness of less than 2 μm, a tensile strength of greater than 500MPa, and the composite has a thickness of less than 5 μm, a tensile strength of greater than 100MPa. And the entire composite is creaseless after more than 200,000 folds.

Inventors

• GAO PING
• GU QIAO
• Dai Zichao

Assignees

• 香港科技大学

Dates

Publication Date

20260508

Application Date

20230320

Priority Date

20220321

Claims (12)

1. 1. A composite for manufacturing a foldable material, the composite comprising: An Ultra High Molecular Weight Polyethylene (UHMWPE) having a highly porous structure of polyethylene, the highly porous structure being formed by interpenetration of UHMWPE nanofibers having a diameter of 10 nm to 40 nm, wherein each fiber comprises a highly ordered arrangement of extended chain fiber crystals comprising folded chain platelet crystals, and A hard coating material, the hard coating consisting of acrylate oligomer and amorphous silica; wherein a first portion of the hard coating material penetrates into the UHMWPE, and Wherein the entire layer of the composite is crease-free after N folds, where N is an integer greater than 200,000.
2. 2. The composite of claim 1, wherein the hardcoat material is deposited in liquid form.
3. 3. The composite material according to claim 1, wherein the UHMWPE is formed as a layer, the second portion of the hard coating material being deposited on the layer.
4. 4. A composite material according to claim 3, wherein the layer of UHMWPE has a thickness of less than 2 μm.
5. 5. A composite according to claim 3, wherein the layer of UHMWPE has a tensile strength of more than 500 MPa.
6. 6. A flexible screen for manufacturing a foldable or rollable display, the flexible screen comprising: The composite material of claim 1; wherein the composite is configured such that when light propagates through the flexible screen, a light transmission of greater than 90% of the visible light is obtained.
7. 7. A transparent substrate for an optical device, the transparent substrate comprising: The composite material of claim 1; Wherein the composite is configured such that when light propagates through the transparent substrate, the light transmittance of the obtained visible light is greater than 90%.
8. 8. A method for manufacturing a composite material for use in manufacturing a foldable or rollable display, the method comprising: Preparing a nanoporous Ultra High Molecular Weight Polyethylene (UHMWPE) substrate having a highly porous structure of polyethylene, the highly porous structure being formed by interpenetration of UHMWPE nanofibers having a diameter of 10 nm to 40 nm, wherein each fiber comprises highly ordered arrangement of extended chain fiber crystals including folded chain lamellar crystals, and Depositing a hard coating material on an upper surface of the UHMWPE substrate such that a portion of the hard coating material penetrates into the internal structure of the UHMWPE substrate, Wherein the hard coating consists of acrylate oligomer and amorphous silica, and Wherein the entire layer of the composite is crease-free after N folds, where N is an integer greater than 200,000.
9. 9. The method of claim 8, wherein the hardcoat material is in liquid form.
10. 10. The method according to claim 8, wherein the UHMWPE substrate is formed as a layer, the hard coating material being deposited on the layer.
11. 11. The method according to claim 10, wherein the thickness of the layer of UHMWPE is less than 2 μm.
12. 12. The method according to claim 10, wherein the layer of UHMWPE has a tensile strength of greater than 500 MPa.

Description

Polyethylene composite material for flexible display screen Cross Reference to Related Applications The present application claims U.S. application sequence No filed on day 21, 3, 2022. 63/322,213, The entire contents of which are incorporated herein by reference, including any tables, figures, or drawings. Technical Field The present application relates to a composite material for display screens and optical devices. More particularly, the present application relates to a composite material comprising Ultra High Molecular Weight Polyethylene (UHMWPE) and a hard coating material, which is useful for flexible display screens/optical devices, a method of manufacturing the composite material, and a flexible screen of a foldable or rollable display manufactured from the composite material. Background In recent years, foldable screens as a new generation of display technology have received attention because of solving the problem that portability and display area are in conflict in demand. One of the key issues impeding the widespread use of foldable displays is the development of foldable substrates and protective screens. Among all materials, flexible transparent plastic films are considered to be the most promising alternative to tempered glass commonly used in current foldable displays. Tempered glass is the first choice for covering windows of rigid displays because of its excellent scratch resistance and overall screen saver capability. Theoretically, a possible way to make glass flexible is to reduce its thickness, however, when the glass is thinned, a great concern about ultra-brittleness may be raised. In fact, a substitute for thick tempered glass is possible to be a combination of plastic film and flexible hard coating to provide glass-like hardness with scratch resistance, excellent transparency and polymer-like flexibility to be able to be highly deformed without damage. Unfortunately, the most advanced techniques developed for producing foldable protective screens/substrates do not fully meet the requirements of high transparency, excellent scratch resistance, crease-free and good mechanical stability. For a smartphone screen cover to protect a display screen, the screen cover is required to have both resiliency and flexibility. Colorless Polyimide (CPI) and polyethylene terephthalate (PET) films are two major materials used in the flexible display industry. However, a significant problem with CPI or PET films is that creases can occur when the film is folded multiple times. Disclosure of Invention There remains a need in the art for improved designs and techniques for composite materials and methods of manufacturing flexible display screens. According to an embodiment of the present application, there is provided a composite for manufacturing a foldable material, the composite comprising Ultra High Molecular Weight Polyethylene (UHMWPE) and a hard coating material, a first portion of the hard coating material penetrating into the UHMWPE. UHMWPE has a highly porous structure of polyethylene. The hard coating material is in liquid form. Furthermore, the UHMWPE is formed as a layer on which the second portion of the hard coating material is deposited. The thickness of the layer of UHMWPE is less than 2 μm. The tensile strength of the layer of UHMWPE is greater than 500MPa. In certain embodiments of the present application, a flexible screen for use in the manufacture of a foldable or rollable display is provided comprising the above composite material configured such that when a hard object scrapes the flexible screen, the flexible screen exhibits a scratch resistance of greater than 5H. In certain embodiments of the present application, there is provided a flexible screen for use in the manufacture of a foldable or rollable display, comprising the above-described composite material configured such that when light propagates through the flexible screen, the light transmittance of the resulting visible light is greater than 90% In some embodiments of the present application, there is provided a transparent substrate for an optical device comprising the above-described composite material configured such that when a hard object scratches the transparent substrate, the transparent substrate exhibits a scratch resistance hardness of greater than 5H. In some embodiments of the present application, there is provided a transparent substrate for an optical device comprising the above-described composite material configured such that when light propagates through the transparent substrate, the light transmittance of the obtained visible light is greater than 90%. In another embodiment of the present application, a method for manufacturing a composite material for use in manufacturing a foldable or rollable display is provided, the method comprising preparing a nanoporous Ultra High Molecular Weight Polyethylene (UHMWPE) substrate, and depositing a hard coating material on an upper surface of the UHMWPE substra