Foldable dimming film

Abstract

The invention provides a foldable dimming film which comprises a bendable base material layer, a first adhesion promoting layer, a conductive layer, a second adhesion promoting layer, a polymer dispersed liquid crystal layer, a second adhesion promoting layer, a conductive layer, a first adhesion promoting layer and a bendable base material layer which are sequentially stacked, and the conductive layer comprises graphene oxide and silver nanowires. The polymer dispersed liquid crystal layer comprises liquid crystals, linear polyurethane acrylate and functionalized polysilsesquioxane, the functionalized polysilsesquioxane accounts for 10%-20% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane, and the bendable base material layer is made of a polymer with polar groups. The first adhesion promoting layer is made of linear polyurethane acrylate, the second adhesion promoting layer is composed of polyester polyol and cellulose, and the mass fraction of the cellulose is 15%-20%. The dimming film provided by the invention has relatively good foldability.

Description

Technical Field

[0001] The present invention relates to the technical field of foldable display, and in particular to a foldable dimming film. Background Art

[0002] Since the dimming film currently in mass production mainly uses ITO conductive film, it has the problem of poor bending resistance. Silver nanowires are conductive materials that are resistant to bending, but when silver nanowires are used in PDLC (abbreviation for polymer dispersed liquid crystal) devices, the adhesion strength between them and the layers affects the foldability of the device. In addition, the structure of each layer of the device and the force between the layers also affect the final foldability of the device. Therefore, it is urgent to explore the design of silver nanowires for PDLC devices. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a foldable dimming film with good foldability.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A foldable dimming film comprises a bendable substrate layer, a first adhesion promoting layer, a conductive layer, a second adhesion promoting layer, a polymer dispersed liquid crystal layer, a second adhesion promoting layer, a conductive layer, a first adhesion promoting layer and a bendable substrate layer stacked in sequence, wherein the conductive layer comprises graphene oxide and silver nanowires, the polymer dispersed liquid crystal layer comprises liquid crystal, linear polyurethane acrylate and functionalized polysilsesquioxane, the functionalized polysilsesquioxane comprises at least one of mercapto functionalized polysilsesquioxane or amino functionalized polysilsesquioxane, in the polymer dispersed liquid crystal layer, the functionalized polysilsesquioxane accounts for 10%-20% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane, the material of the bendable substrate layer is a polymer having a polar group, the material of the first adhesion promoting layer is linear polyurethane acrylate, the components of the second adhesion promoting layer are composed of polyester polyol and cellulose, and the mass fraction of the cellulose in the components of the second adhesion promoting layer is 15%-20%.

[0006] In some possible embodiments, the ratio of the silver nanowires to the graphene oxide is 30-40:1 by weight.

[0007] In some possible embodiments, in the polymer dispersed liquid crystal layer, the functionalized polysilsesquioxane accounts for 10% to 13% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane.

[0008] In some possible embodiments, the material of the bendable substrate layer includes at least one of polymethacrylic acid, polyvinyl alcohol or polyvinyl chloride.

[0009] In some possible embodiments, the polyester polyol is an aliphatic polyester polyol.

[0010] In some possible embodiments, in the components of the second bonding promotion layer, the mass fraction of the cellulose is 17%-19%.

[0011] In some possible embodiments, the bendable substrate layer has a thickness of 20-50 μm.

[0012] In some possible embodiments, the thickness of the first adhesion promoting layer is 20-30 μm, and the thickness of the second adhesion promoting layer is 15-18 μm.

[0013] In some possible embodiments, the thickness of the polymer dispersed liquid crystal layer is 20-40 μm.

[0014] In some possible embodiments, it further includes:

[0015] The OCA adhesive layer is bonded to at least one end surface of the bendable substrate layer away from the first adhesion promoting layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In the present application, graphene oxide, silver nanowires, and cellulose form an interpenetrating winding structure, which is beneficial to improve the interaction between the layers, and also to improve the connection stability of the silver nanowires, thereby facilitating the folding resistance of the silver nanowires. In addition, graphene oxide (having hydroxyl and carboxyl groups that can form intermolecular hydrogen bonds), linear polyurethane acrylate, functionalized polysilsesquioxane, polyester polyol, cellulose, and bendable substrate layers can form intermolecular hydrogen bonds, thereby ensuring the connection strength between the layers, and the materials of each layer are selected from polymers with good flexibility, thereby facilitating the synergistic effect to improve the foldability of the foldable dimming film. In addition, the microscopic cage structure formed by the functionalized polysilsesquioxane can form intralayer doping, thereby facilitating further improving the flexibility of the polymer dispersed liquid crystal layer. Therefore, the foldable dimming film provided by the present application has good foldability due to the synergistic cooperation between the materials of each layer.

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A cross-sectional view of a foldable dimming film provided in accordance with an embodiment of the present application.

[0020] Description of Figure Numbers:

[0021] 10 - bendable substrate layer; 20 - first adhesion promoting layer; 30 - conductive layer; 40 - second adhesion promoting layer; 50 - polymer dispersed liquid crystal layer; 60 - OCA adhesive layer. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. It should be noted that when an element is referred to as "fixed to" another element, it can be directly on the other element or there can be a centered element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there can be a centered element. When an element is referred to as "arranged on" another element, it can be arranged on the other element or there can be a centered element.

[0024] An embodiment of the present application provides a foldable dimming film, which includes a bendable substrate layer 10, a first adhesion promoting layer 20, a conductive layer 30, a second adhesion promoting layer 40, a polymer dispersed liquid crystal layer (PDLC layer) 50, a second adhesion promoting layer 40, a conductive layer 30, a first adhesion promoting layer 20 and a bendable substrate layer 10 stacked in sequence. The conductive layer 30 includes graphene oxide and silver nanowires. The polymer dispersed liquid crystal layer 50 includes liquid crystal, linear polyurethane acrylate and functionalized polysilsesquioxane. Exemplarily, the polymer dispersed liquid crystal layer 50 may also include a spacer. The functionalized polysilsesquioxane includes a mercapto-functionalized polysilsesquioxane or an amino-functionalized polysilsesquioxane. In the polymer dispersed liquid crystal layer 50, the functionalized polysilsesquioxane accounts for 10%-20% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane. Exemplarily, the mass fraction of the functionalized polysilsesquioxane can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or a value between any two of the above numerical ranges. The selection of the mass fraction of the functionalized polysilsesquioxane is beneficial to regulating the surface energy of the polymer dispersed liquid crystal layer 50 on the one hand, and to regulating the toughness of the microcage structure formed by the functionalized polysilsesquioxane on the other hand. The material of the bendable substrate layer 10 is a polymer having a polar group. The material of the first adhesion promoting layer 20 is linear polyurethane acrylate. The components of the second adhesion promoting layer 40 are composed of polyester polyol and cellulose. In the components of the second adhesion promoting layer 40, the mass fraction of the cellulose is 15%-20%, and can be 15%, 16%, 17%, 18%, 19%, 20% or a value between any two of the above numerical ranges. The selection of the mass fraction range of cellulose is conducive to improving the synergistic effect of polyester polyol and cellulose.

[0025] In the present application, graphene oxide, silver nanowires, and cellulose form an interpenetrating winding structure, which is beneficial to improve the interaction between the layers, and also to improve the connection stability of the silver nanowires, thereby facilitating the folding resistance of the silver nanowires. In addition, graphene oxide (having hydroxyl and carboxyl groups that can form intermolecular hydrogen bonds), linear polyurethane acrylate, functionalized polysilsesquioxane, polyester polyol, cellulose, and bendable substrate layers can form intermolecular hydrogen bonds, thereby ensuring the connection strength between the layers, and the materials of each layer are selected from polymers with good flexibility, thereby facilitating the synergistic effect to improve the foldability of the foldable dimming film. In addition, the microscopic cage structure formed by the functionalized polysilsesquioxane can form intralayer doping, thereby facilitating further improving the flexibility of the polymer dispersed liquid crystal layer. Therefore, the foldable dimming film provided by the present application has good foldability due to the synergistic cooperation between the materials of each layer.

[0026] In some embodiments, the liquid crystal may include a fluorine-containing liquid crystal.

[0027] Exemplarily, when preparing the foldable dimming film, the bendable substrate layer 10, the first adhesion promoting layer 20, the conductive layer 30 and the second adhesion promoting layer 40 can be connected to form an intermediate, and then the polymer dispersed liquid crystal layer 50 is composited between the two intermediates. The curing method of each layer can be appropriately selected according to the characteristics of the material, such as heating curing or ultraviolet irradiation curing. Exemplarily, when preparing the conductive layer 30, both graphene oxide and silver nanowires can be added to isopropyl alcohol and / or deionized water to form a dispersion, and then the corresponding conductive layer 30 is formed by roller coating and drying.

[0028] Exemplarily, graphene oxide can be prepared by the following method: 1.0 g of graphite powder and 23 mL of concentrated sulfuric acid are added to a 250 mL flask under ice bath and mechanical stirring (200 rpm), and then 3.0 g of KMnO4 to keep the temperature of the suspension below 20°C; then the reaction system was transferred to an oil bath at 40°C and stirred vigorously (300 rpm) for 0.5 hours, then 50 mL of water was added, and the reaction was stirred at 95°C for another 15 minutes, followed by the addition of another 150 mL of water, and then 5 mL of 30 wt% H2O2 solution was added dropwise, and the color of the reaction system changed from dark brown to yellow; the resulting mixture was filtered and washed with 1:9 HCl aqueous solution (50 mL each, 3 times) to remove metal ions, and the resulting solid was dried in air and dispersed in 300 mL of water to form an aqueous graphene oxide dispersion; finally, the dialysis membrane with a molecular weight cutoff of 8000-14000 g / mol was used for one week to remove residual acid and metal substances, and then the resulting graphene aqueous dispersion was stirred overnight and ultrasonically treated for 30 minutes to exfoliate it to graphene oxide nanosheets. It is understood that graphene oxide can also be purchased from the market for use.

[0029] In some embodiments, the weight ratio of the silver nanowires to the graphene oxide is 30-40:1, thereby further improving the synergy between the components of the conductive layer 30 and further improving the foldability of the film.

[0030] In some embodiments, in the polymer dispersed liquid crystal layer 50, the functionalized polysilsesquioxane accounts for 10%-13% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane, thereby facilitating the regulation of the surface energy within a suitable range to improve the bonding strength between the layers, and also facilitating the regulation of the toughening effect of the microcage structure to be better.

[0031] In some embodiments, the material of the bendable substrate layer 10 includes at least one of polymethacrylic acid, polyvinyl alcohol, or polyvinyl chloride. The selection of the above materials can have good toughness and be conducive to forming strong intermolecular hydrogen bonds.

[0032] In some embodiments, the polyester polyol is an aliphatic polyester polyol, which helps to further increase the foldability of the film.

[0033] In some embodiments, in the components of the second adhesion promoting layer 40 , the mass fraction of the cellulose is 17%-19%.

[0034] In some embodiments, the thickness of the bendable substrate layer 10 is 20-50 μm.

[0035] In some embodiments, the thickness of the first adhesion promoting layer 20 is 20-30 μm, and the thickness of the second adhesion promoting layer 40 is 15-18 μm.

[0036] In some embodiments, the thickness of the conductive layer 30 is 20-30 μm.

[0037] In some embodiments, the thickness of the polymer dispersed liquid crystal layer 50 is 20-40 μm.

[0038] The selection of the above thickness range is conducive to reducing the adverse effects of stress caused by the thickness, thereby helping to further improve the foldability of the film.

[0039] In some embodiments, the foldable dimming film further includes an OCA (Optically Clear Adhesive) adhesive layer 60, which is at least bonded to an end surface of the bendable substrate layer 10 away from the first adhesion promoting layer 20. The OCA adhesive layer 60 is beneficial for improving optical performance, reducing reflection, increasing transmittance, and enhancing display effects.

[0040] Example 1

[0041] A foldable dimming film comprises a bendable substrate layer 10, a first adhesion promoting layer 20, a conductive layer 30, a second adhesion promoting layer 40, a polymer dispersed liquid crystal layer 50, a second adhesion promoting layer 40, a conductive layer 30, a first adhesion promoting layer 20 and a bendable substrate layer 10 which are stacked in sequence, wherein the conductive layer 30 comprises graphene oxide (prepared according to the method discussed above) and silver nanowires (JK-03-011 of Jike Biotechnology), and the polymer dispersed liquid crystal layer 50 comprises liquid crystal (propyl dicyclohexyl-3,4,5-trifluorobiphenyl liquid crystal material, Beijing Bayi Spacetime Liquid Crystal Technology Co., Ltd.), linear polyurethane acrylate (Zhanxin EBECRYL 4101 aliphatic polyurethane acrylate) and functionalized polysilsesquioxane (amino functionalized polysilsesquioxane, Xi'an Qiyue Biotechnology Co., Ltd.), in the polymer dispersed liquid crystal layer 50, the functionalized polysilsesquioxane accounts for 10% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane, the material of the bendable substrate layer 10 is polymethacrylic acid (25087-26-7, Nantong Runfeng Petrochemical Co., Ltd.), the material of the first adhesion promoting layer 20 is linear polyurethane acrylate (Zhanxin EBECRYL 4101 aliphatic polyurethane acrylate), the components of the second adhesion promoting layer 40 are composed of polyester polyol (Huijinchuan, aliphatic polyester polyol) and cellulose (9004-34-6, Alfa Aesar), and the mass fraction of cellulose in the components of the second adhesion promoting layer 40 is 20%. By weight, the silver nanowire: the graphene oxide is 35:1. The thickness of the bendable substrate layer 10 is 22μm. The thickness of the first adhesion promoting layer 20 is 20 μm, and the thickness of the second adhesion promoting layer 40 is 17 μm. The thickness of the polymer dispersed liquid crystal layer 50 is 20 μm. The thickness of the conductive layer 30 is 20 μm. The foldable dimming film also includes an OCA adhesive layer 60, which is bonded to the end face of a bendable substrate layer 10 away from the first adhesion promoting layer 20. The performance of the film remains basically unchanged after being bent 2000 times.

[0042] Example 2

[0043] The difference from Example 1 is that the material of the bendable substrate layer 10 is polyvinyl alcohol (9002-89-5, Acros Organics). In the polymer dispersed liquid crystal layer 50, the functionalized polysilsesquioxane accounts for 13% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane. Among the components of the second adhesion promoting layer 40, the mass fraction of cellulose is 15%. By weight, the silver nanowire: the graphene oxide is 30:1. The thickness of the bendable substrate layer 10 is 20μm. The thickness of the first adhesion promoting layer 20 is 25μm, and the thickness of the second adhesion promoting layer 40 is 15μm. The thickness of the conductive layer 30 is 30μm. The thickness of the polymer dispersed liquid crystal layer 50 is 35μm. The performance of the film remains basically unchanged after being bent 2000 times.

[0044] Example 3

[0045] The difference from Example 2 is that the material of the bendable substrate layer 10 is polyvinyl chloride (Qilu brand S-700 8 type). The mass fraction of cellulose in the components of the second adhesion promoting layer 40 is 17%. By weight, the silver nanowire: the graphene oxide is 40:1. The thickness of the bendable substrate layer 10 is 50 μm. The thickness of the first adhesion promoting layer 20 is 30 μm, and the thickness of the second adhesion promoting layer 40 is 18 μm. The thickness of the polymer dispersed liquid crystal layer 50 is 40 μm. The performance of the film remains basically unchanged after being bent 3000 times.

[0046] Example 4

[0047] The difference from Example 3 is that the mass fraction of cellulose in the components of the second adhesion promoting layer 40 is 19%. The performance of the film remains substantially unchanged after being bent 3500 times.

[0048] Example 5

[0049] The difference from Example 1 is that the functionalized polysilsesquioxane is mercapto-functionalized polysilsesquioxane (Xi'an Qiyue Biotechnology Co., Ltd.) The performance of the film remained basically unchanged after being bent 2000 times.

[0050] Comparative Example 1

[0051] The difference from Example 1 is that the conductive layer 30 lacks graphene oxide. The performance of the film remains basically unchanged after being bent 1300 times.

[0052] Comparative Example 2

[0053] The difference from Example 1 is that the polymer dispersed liquid crystal layer 50 lacks functionalized polysilsesquioxane. The performance of the film remains basically unchanged after being bent 1400 times.

[0054] Comparative Example 3

[0055] The difference from Example 1 is that the second adhesion promoting layer 40 lacks cellulose. The performance of the film remains substantially unchanged after being bent 1200 times.

[0056] The present application tests the folding resistance of the foldable dimming film by the testing method of the GOST 8978-1975 standard.

[0057] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A foldable dimming film, characterized in that: The invention comprises a bendable substrate layer, a first adhesion promoting layer, a conductive layer, a second adhesion promoting layer, a polymer dispersed liquid crystal layer, a second adhesion promoting layer, a conductive layer, a first adhesion promoting layer and a bendable substrate layer which are stacked in sequence, wherein the conductive layer comprises graphene oxide and silver nanowires, the polymer dispersed liquid crystal layer comprises liquid crystal, linear polyurethane acrylate and functionalized polysilsesquioxane, the functionalized polysilsesquioxane comprises at least one of mercapto functionalized polysilsesquioxane or amino functionalized polysilsesquioxane, in the polymer dispersed liquid crystal layer, the functionalized polysilsesquioxane accounts for 10%-20% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane, the material of the bendable substrate layer is a polymer having a polar group, the material of the first adhesion promoting layer is linear polyurethane acrylate, the components of the second adhesion promoting layer are composed of polyester polyol and cellulose, and the mass fraction of the cellulose in the components of the second adhesion promoting layer is 15%-20%.

2. The foldable dimming film according to claim 1, characterized in that: By weight, the silver nanowire:graphene oxide is 30-40:

1.

3. The foldable dimming film according to claim 1, characterized in that: In the polymer dispersed liquid crystal layer, the functionalized polysilsesquioxane accounts for 10% to 13% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane.

4. The foldable dimming film according to claim 1, characterized in that: The material of the bendable substrate layer includes at least one of polymethacrylic acid, polyvinyl alcohol or polyvinyl chloride.

5. The foldable dimming film according to claim 1, characterized in that: The polyester polyol is an aliphatic polyester polyol.

6. The foldable dimming film according to claim 1, characterized in that: Among the components of the second bonding promotion layer, the mass fraction of the cellulose is 17%-19%.

7. The foldable dimming film according to claim 1, characterized in that: The thickness of the bendable substrate layer is 20-50 μm.

8. The foldable dimming film according to claim 7, characterized in that: The thickness of the first adhesion promoting layer is 20-30 μm, and the thickness of the second adhesion promoting layer is 15-18 μm.

9. The foldable dimming film according to claim 8, characterized in that: The thickness of the polymer dispersed liquid crystal layer is 20-40 μm.

10. The foldable light-adjustable film according to any one of claims 1 to 9, characterized in that: Also includes: The OCA adhesive layer is bonded to at least one end surface of the bendable substrate layer away from the first adhesion promoting layer.

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