Foldable dimming film

Abstract

The present application provides a foldable dimming film comprising 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. The conductive layer comprises graphene oxide and silver nanowires, and the polymer-dispersed liquid crystal layer comprises liquid crystal, linear polyurethane acrylate, and functionalized polysilsesquioxane, with the functionalized polysilsesquioxane accounting for 10%-20% of the total mass of the linear polyurethane acrylate and the functionalized polysilsesquioxane. The bendable substrate layer is made of a polymer with polar groups, the first adhesion-promoting layer is made of linear polyurethane acrylate, and the second adhesion-promoting layer is composed of polyester polyol and cellulose, with the mass fraction of cellulose being 15%-20%. The dimming film of the present application has 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 currently mass-produced dimming films primarily utilize ITO conductive film, they suffer from poor flex resistance. Silver nanowires are a highly flex-resistant conductive material, but when used in PDLC (polymer dispersed liquid crystal) devices, the adhesion strength between the nanowires and the layers affects the device's foldability. Furthermore, the structure of the device's layers and the forces between them also influence the device's ultimate foldability. Therefore, there is an urgent need to explore the design of PDLC devices using silver nanowires. Summary of the Invention

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

[0004] In order to solve the above problems, the technical solutions adopted by the present invention are 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 and amino-functionalized polysilsesquioxane, and 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 polar groups, 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, the mass fraction of the cellulose in the components of the second bonding promotion layer 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, the following further comprises:

[0015] The OCA adhesive layer is bonded to at least one end surface of the bendable substrate layer facing 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 entangled structure, which is beneficial for increasing the interaction between the layers while also improving 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 capable of forming intermolecular hydrogen bonds), linear polyurethane acrylate, functionalized polysilsesquioxane, polyester polyol, cellulose, and the bendable substrate layer 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 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 will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A cross-sectional view of a foldable dimming film according to 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this 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 an element in the middle. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there can be an element in the middle. When an element is referred to as "set on" another element, it can be set on the other element or there can be an element in the middle.

[0024] One embodiment of the present application provides a foldable dimming film, comprising 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 comprises graphene oxide and silver nanowires. The polymer-dispersed liquid crystal layer 50 comprises liquid crystal, linear polyurethane acrylate, and a functionalized polysilsesquioxane. Exemplarily, the polymer-dispersed liquid crystal layer 50 may further comprise a spacer. The functionalized polysilsesquioxane comprises a mercapto-functionalized polysilsesquioxane or an amino-functionalized polysilsesquioxane. In the polymer-dispersed liquid crystal layer 50, the functionalized polysilsesquioxane comprises 10% to 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 any value between any two of the aforementioned ranges. The selected mass fraction of the functionalized polysilsesquioxane facilitates both regulating the surface energy of the polymer-dispersed liquid crystal layer 50 and controlling the toughness of the microcage structure formed by the functionalized polysilsesquioxane. The flexible substrate layer 10 is made of a polymer having polar groups. The first adhesion-promoting layer 20 is made of a linear polyurethane acrylate. The second adhesion-promoting layer 40 is composed of polyester polyol and cellulose. The mass fraction of cellulose in the second adhesion-promoting layer 40 is 15% to 20%. For example, it can be 15%, 16%, 17%, 18%, 19%, 20%, or any value between any two of the aforementioned ranges. This selected mass fraction range of cellulose helps enhance the synergistic effect between the polyester polyol and the cellulose.

[0025] In the present application, graphene oxide, silver nanowires, and cellulose form an interpenetrating entangled structure, which is beneficial for increasing the interaction between the layers while also improving 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 capable of forming intermolecular hydrogen bonds), linear polyurethane acrylate, functionalized polysilsesquioxane, polyester polyol, cellulose, and the bendable substrate layer 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 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] For example, when preparing a foldable dimming film, the flexible 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 body. A polymer-dispersed liquid crystal layer 50 can then be composited between the two intermediate bodies. Each layer can be cured by heat or UV curing, depending on the material properties. For example, when preparing the conductive layer 30, graphene oxide and silver nanowires can be added to isopropyl alcohol and / or deionized water to form a dispersion, which can then be roller-coated and dried to form the corresponding conductive layer 30.

[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 was added to maintain the suspension temperature below 20°C. The reaction system was then transferred to a 40°C oil bath and stirred vigorously (300 rpm) for 0.5 hours. 50 mL of water was then added and the reaction was stirred at 95°C for another 15 minutes. An additional 150 mL of water was then added, followed by the dropwise addition of 5 mL of a 30 wt% H2O2 solution, which caused the color of the reaction system to change from dark brown to yellow. The resulting mixture was filtered and washed with 1:9 aqueous HCl (50 mL each, three times) to remove metal ions. The resulting solid was air-dried and dispersed in 300 mL of water to form an aqueous graphene oxide dispersion. Finally, the dispersion was dialyzed for one week using a dialysis membrane with a molecular weight cutoff of 8,000-14,000 g / mol to remove residual acid and metal species. The resulting aqueous graphene dispersion was then stirred overnight and sonicated for 30 minutes to exfoliate it into graphene oxide nanosheets. It is understood that commercially available graphene oxide can also be used.

[0029] In some embodiments, the weight ratio of the silver nanowires to the graphene oxide is 30-40:1, thereby further improving the synergistic effect 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.

[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 facilitate the formation of strong intermolecular hydrogen bonds.

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

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

[0034] In some embodiments, the bendable substrate layer 10 has a thickness of 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 thickness, thereby further improving the foldability of the film.

[0039] In some embodiments, the foldable dimming film further includes an optically clear adhesive (OCA) layer 60, which is bonded to at least one end surface of the flexible substrate layer 10 facing away from the first adhesion-promoting layer 20. The OCA layer 60 improves optical performance, reduces reflections, increases transmittance, and enhances display quality.

[0040] Example 1

[0041] A foldable dimming film 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 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. The conductive layer 30 includes graphene oxide (prepared according to the method discussed above) and silver nanowires (JK-03-011 from Chico Biotechnology). The polymer dispersed liquid crystal layer 50 includes liquid crystal (propyl dicyclohexyl-3,4,5-trifluorobiphenyl liquid crystal material, Beijing Bayi Space-Time 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 weight of the linear polyurethane acrylate and the functionalized polysilsesquioxane. The flexible substrate layer 10 is made of polymethacrylic acid (25087-26-7, Nantong Runfeng Petrochemical Co., Ltd.). The first adhesion-promoting layer 20 is made of linear polyurethane acrylate (EBECRYL 4101 aliphatic polyurethane acrylate). The second adhesion-promoting layer 40 is composed of polyester polyol (Huijinchuan, aliphatic polyester polyol) and cellulose (9004-34-6, Alfa Aesar). The mass fraction of cellulose in the second adhesion-promoting layer 40 is 20%. The weight ratio of the silver nanowires to the graphene oxide is 35:1. The thickness of the flexible substrate layer 10 is 22 μm. 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 surface of the bendable substrate layer 10 facing away from the first adhesion-promoting layer 20. The film's performance remains essentially unchanged after being bent 2,000 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. The mass fraction of cellulose in the components of the second adhesion-promoting layer 40 is 15%. The weight ratio of the silver nanowires to the graphene oxide is 30:1. The thickness of the bendable substrate layer 10 is 20 μm. The thickness of the first adhesion-promoting layer 20 is 25 μm, and the thickness of the second adhesion-promoting layer 40 is 15 μm. The thickness of the conductive layer 30 is 30 μm. The thickness of the polymer-dispersed liquid crystal layer 50 is 35 μm. The performance of the film remains essentially 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 type 8). The mass fraction of cellulose in the components of the second adhesion-promoting layer 40 is 17%. The weight ratio of the silver nanowires to 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 essentially 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 a mercapto-functionalized polysilsesquioxane (from Xi'an Qiyue Biotechnology Co., Ltd.) The performance of the film remained substantially 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 substantially 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 test method of the GOST 8978-1975 standard.

[0057] The above 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 replacements made by technicians in this field on the basis of the present invention 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 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 and amino-functionalized polysilsesquioxane, and 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 polar groups, 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 light-switching film according to claim 1, wherein: By weight, the ratio of the silver nanowires to the graphene oxide is 30-40:

1.

3. The foldable light-switching film according to claim 1, wherein: 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 light-switching film according to claim 1, wherein: The material of the bendable substrate layer includes at least one of polymethacrylic acid, polyvinyl alcohol or polyvinyl chloride.

5. The foldable light-switching film according to claim 1, wherein: The polyester polyol is an aliphatic polyester polyol.

6. The foldable light-switching film according to claim 1, wherein: Among the components of the second adhesion promoting layer, the mass fraction of the cellulose is 17%-19%.

7. The foldable light-switching film according to claim 1, wherein: The thickness of the bendable substrate layer is 20-50 μm.

8. The foldable light-switching film according to claim 7, wherein: 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 light-switching film according to claim 8, wherein: The thickness of the polymer dispersed liquid crystal layer is 20-40 μm.

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

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