Hardening film and foldable electronic product

Abstract

The embodiment of the invention provides a hard coating film and a foldable electronic product, and relates to the field of electronic product protective films. The hardened film comprises a base material layer, and a first hardened layer, a second hardened layer and a third hardened layer which are sequentially laminated on the base material layer, wherein the first hardening liquid comprises first polyurethane acrylic resin; the second hardening liquid comprises first polyurethane acrylic resin, second polyurethane acrylic resin and a blue light absorbent; the third hardening liquid comprises second polyurethane acrylic resin and an ultraviolet light absorber; the functionality of the first polyurethane acrylic resin is 6-12, the functionality of the second polyurethane acrylic resin is 1-6, and the functionality of the first polyurethane acrylic resin is greater than that of the second polyurethane acrylic resin. The hard coating film and the foldable electronic product provided by the embodiment of the invention not only have good bending resistance, but also have excellent blue light resistance.

Description

Technical Field

[0001] This application relates to the field of protective films for electronic products, and more specifically, to a hardened film and a foldable electronic product. Background Technology

[0002] With the ever-increasing functionality of 3C electronic products such as mobile phones, computers, and televisions, people are spending more and more time in front of these devices every day. Prolonged screen time can lead to dry and sore eyes. One contributing factor is the strong penetrating power of short-wavelength blue light (415-455nm) emitted from these screens, which can damage retinal cells and increase the risk of macular degeneration (AMD). Furthermore, users now spend a significant amount of time using electronic devices at night, and the blue light emitted from the screens may cause insomnia, poor sleep quality, and skin aging. Therefore, adding blue light filtering functionality to the screens of existing electronic products is urgently needed.

[0003] In recent years, foldable phones (with foldable covers) have become one of the mainstream products in the mobile phone market, but existing protective films used for foldable covers are difficult to balance blue light resistance and bending resistance. Summary of the Invention

[0004] The purpose of this application is to provide a hardened film and a foldable electronic product, wherein the hardened film not only has good bending resistance, but also has excellent anti-blue light performance.

[0005] In a first aspect, embodiments of this application provide a hardening film, which includes a substrate layer and a first hardening layer, a second hardening layer and a third hardening layer sequentially stacked on the substrate layer; Wherein, the first curing liquid corresponding to the first curing layer includes a first polyurethane acrylic resin; The second curing liquid corresponding to the second curing layer contains a first polyurethane acrylic resin, a second polyurethane acrylic resin, and a blue light absorber. The weight ratio of the first polyurethane acrylic resin, the second polyurethane acrylic resin, and the blue light absorber in the second curing liquid is (40~60):(40~60):(3~6). The third curing liquid corresponding to the third curing layer contains a second polyurethane acrylic resin and an ultraviolet light absorber; The first polyurethane acrylic resin has a functionality of 6 to 12, the second polyurethane acrylic resin has a functionality of 1 to 6, and the functionality of the first polyurethane acrylic resin is greater than that of the second polyurethane acrylic resin.

[0006] In the above technical solution, the first polyurethane acrylic resin has a functionality of 6-12, corresponding to high hardness and moderate toughness, while the second polyurethane acrylic resin has a functionality of 1-6, corresponding to moderate hardness and good toughness. The first, second, and third hardening layers are formed using the first polyurethane acrylic resin, the first polyurethane acrylic resin + second polyurethane acrylic resin, and the second polyurethane acrylic resin, respectively, resulting in a multi-layered structure with gradually decreasing hardness and gradually increasing toughness, thus ensuring good bending resistance. Furthermore, the hardening film of this application incorporates a certain proportion of blue light absorber in the second hardening layer to provide good blue light protection, and the addition of an ultraviolet light absorber in the third hardening layer assists the blue light absorber in improving blue light protection performance.

[0007] In one possible implementation, the third curing liquid further includes an acrylate monomer, wherein the acrylate monomer includes at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; and / or, the functionality of the acrylate monomer is ≥2. And / or, the weight ratio of the ultraviolet absorber to the second polyurethane acrylic resin in the third hardening liquid is (1~20):(60~80); And / or, the third hardening liquid further includes a leveling agent, and the weight ratio of the leveling agent to the second polyurethane acrylic resin is (0.3~1):(60~80).

[0008] In the above technical solution, the third curing liquid also contains acrylate monomers, which can improve the adhesion between adjacent layers, thereby enabling the whole to have excellent bending performance; the third curing liquid also contains a leveling agent in a specific mass ratio to control the water contact angle on the surface of the curing layer, thereby ensuring its application effect.

[0009] In one possible implementation, the components of the third hardening liquid, by weight, include: 60-80 parts of the second polyurethane acrylic resin; 20-40 parts of acrylate monomer; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.3~1 part; 1-20 parts of ultraviolet light absorber.

[0010] In one possible implementation, the absorption peak range of the blue light absorber in the second hardening liquid is 380~450nm; and / or, the blue light absorber includes at least one of cyanoacrylate blue light absorbers, benzotriazole blue light absorbers, and cerium oxide. And / or, the weight ratio of the first polyurethane acrylate resin, the second polyurethane acrylate resin and the blue light absorber in the second hardening liquid is (40~60):(40~60):(3~6).

[0011] In the above technical solution, the blue light absorber in the second hardening liquid adopts the above-mentioned specific mass ratio to ensure the anti-blue light effect and optical performance.

[0012] In one possible implementation, the components of the second hardening liquid, by weight, include: 40-60 parts of the first polyurethane acrylic resin; 40-60 parts of the second polyurethane acrylic resin; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.01~0.5 parts; 3-6 parts of blue light absorber.

[0013] In one possible implementation, the components of the first hardening liquid, by weight, include: 100 parts of the first polyurethane acrylic resin; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.01~0.5 parts.

[0014] In one possible implementation, the photoinitiator comprises α-aminoketones or acylphosphine oxides; And / or, the organic solvent includes at least one of ethanol, isopropanol, butanol, acetone, butanone, cyclohexanone, ethyl acetate, butyl acetate, and dimethylacetamide; And / or, the nanofiller includes at least one of alumina, zinc oxide, and silicon dioxide, with a particle size of 10 nm to 100 nm; And / or, the leveling agent includes a fluorinated acrylic compound.

[0015] In one possible implementation, the total thickness of the first hardened layer, the second hardened layer, and the third hardened layer is ≤4μm; And / or, the material of the substrate layer includes at least one of polyethylene terephthalate, cellulose triacetate, polycarbonate, polyethylene, polypropylene, transparent polyimide, polymethyl methacrylate, thermoplastic polyurethane, and polyethylene naphthalate. And / or, the thickness of the substrate layer is 23~125μm.

[0016] In the above technical solution, the total thickness of the first hardening layer, the second hardening layer and the third hardening layer is ≤4μm to ensure excellent overall outward folding capability.

[0017] In one possible implementation, the hardness of the first hardened layer is ≥2H, the thickness is ≤2μm, and the water contact angle of the first hardened layer is 50~70°. And / or, the hardness of the second hardened layer is ≥2H, the thickness is ≤1μm, and the water contact angle of the second hardened layer is 50°~70°; And / or, the water contact angle of the third hardened layer is 95~105°; And / or, the water contact angle of the hardened film is 95~105°, the elongation at break of the coating is >3%, the hardness is ≥2H, and the transmittance at 400nm is ≤20%.

[0018] In the above technical solution, the first hardening layer has requirements for hardness and thickness. The pencil hardness is greater than or equal to 2H, and the coating thickness is ≤2μm. To ensure adhesion between the second hardening layer and the first hardening layer, the surface area of ​​the first hardening layer cannot be too low. Therefore, the water contact angle of the first hardening layer is between 50° and 70°. This design is to ensure the adhesion between the first and second hardening layers and to ensure excellent chemical bonding. The second hardening layer has requirements for hardness, thickness, and surface water contact angle. The hardness is ≥2H, the coating thickness is ≤1μm, and the water contact angle is between 50° and 70°. This design is to ensure the adhesion between the second hardening layer and the first and third hardening layers and to ensure excellent chemical bonding. The water contact angle of the third coating layer is between 95° and 105° to ensure that the interfacial peel force between the protective film adhesive layer and the coating surface is ≥210g / mm, so as to reduce the occurrence of bubble delamination when bending the protective film and the film layer after the protective film is applied to the final product. The elongation at break of the hardened film coating is >3%, and the flexibility of the resin in different layers is designed to meet excellent inward and outward folding ability.

[0019] Secondly, embodiments of this application provide a foldable electronic product, which includes the hardened film provided in the first aspect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic diagram of the structure of a hardened membrane provided in an embodiment of this application.

[0022] Icons: 110 - Substrate layer; 120 - First hardening layer; 130 - Second hardening layer; 140 - Third hardening layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] The following is a detailed description of the hardened film and foldable electronic product according to embodiments of this application.

[0025] Please refer to Figure 1 This application provides a hardening film, which includes a substrate layer 110 and a first hardening layer 120, a second hardening layer 130 and a third hardening layer 140 sequentially stacked on the substrate layer 110. The first curing liquid corresponding to the first curing layer 120 includes a first polyurethane acrylic resin; The second curing liquid corresponding to the second curing layer 130 includes a first polyurethane acrylic resin, a second polyurethane acrylic resin and a blue light absorber. The weight ratio of the first polyurethane acrylic resin, the second polyurethane acrylic resin and the blue light absorber in the second curing liquid is (40~60):(40~60):(3~6). The third curing liquid corresponding to the third curing layer 140 contains a second polyurethane acrylic resin and an ultraviolet light absorber; The first polyurethane acrylic resin has a functionality of 6 to 12, the second polyurethane acrylic resin has a functionality of 1 to 6, and the functionality of the first polyurethane acrylic resin is greater than that of the second polyurethane acrylic resin.

[0026] In this application, the first, second, and third curing liquids are cured to form corresponding first curing layer 120, second curing layer 130, and third curing layer 140. The resin and other components in the first, second, and third curing liquids undergo changes during the curing reaction. The first polyurethane acrylic resin in the first curing layer 120 and the second curing layer 130 may be the same or different, and the second polyurethane acrylic resin in the second curing layer 130 and the third curing layer 140 may be the same or different; this application does not impose any limitations on this.

[0027] Functionality refers to the number of functional groups that actually participate in the reaction of a monomer molecule during a condensation reaction. For polyurethane acrylic resin, its functionality is related to hardness and toughness. Under the same conditions, the greater the functionality of the polyurethane acrylic resin, the higher the hardness and the worse the toughness of the resulting coating, and vice versa.

[0028] In this embodiment, the first polyurethane acrylic resin has a functionality of 6-12, corresponding to high hardness and moderate toughness, while the second polyurethane acrylic resin has a functionality of 1-6, corresponding to moderate hardness and good toughness. The first hardened layer 120, the second hardened layer 130, and the third hardened layer 140 are formed using the first polyurethane acrylic resin, the first polyurethane acrylic resin + the second polyurethane acrylic resin, and the second polyurethane acrylic resin, respectively, so that the overall structure can form a multilayer structure with gradually decreasing hardness and gradually increasing toughness. Specifically, the hardness of the hardened film of this application can satisfy the following relationship: first hardened layer 120 > second hardened layer 130 > third hardened layer 140, and the toughness can satisfy the following relationship: first hardened layer 120 < second hardened layer 130 < third hardened layer 140, thereby ensuring good bending resistance.

[0029] Furthermore, the hardened film of this application incorporates a certain amount of blue light absorber in the second hardened layer 130, giving it excellent blue light protection. Specifically, the blue light absorber added to the second hardened layer 130 primarily absorbs short-wavelength blue light from the visible spectrum, thereby achieving the screen's blue light protection effect. The amount of blue light absorber added can be adjusted to ensure excellent blue light protection while also meeting optical performance requirements. Simultaneously, an ultraviolet light absorber is added to the third hardened layer 140 to assist the blue light absorber and further enhance the blue light protection performance.

[0030] In some embodiments of this application, no blue light absorber, ultraviolet light absorber or other optical additives are added to the first hardened layer 120.

[0031] In this embodiment, no blue light absorber or other additives are added to the first hardened layer 120 to ensure the interfacial adhesion of the first hardened layer 120 in contact with the substrate layer 110, thereby ensuring the overall bending performance. If blue light absorber or other additives are added directly to the first hardened layer 120 near the substrate layer 110, the coating will not cure completely, resulting in weak interfacial adhesion, affecting the overall bending performance, and the coating is prone to peeling off after aging test.

[0032] In some embodiments of this application, no blue light absorber is added to the third hardening layer 140.

[0033] In this embodiment, no blue light absorber is added to the third hardening layer 140 to avoid fogging on the surface of the hardened film due to the precipitation of blue light absorber, which would affect the overall optical performance of the coating.

[0034] In some embodiments of this application, the total thickness of the first hardening layer 120, the second hardening layer 130, and the third hardening layer 140 is ≤4μm.

[0035] In this embodiment, the total thickness of the first hardening layer 120, the second hardening layer 130 and the third hardening layer 140 is ≤4μm to ensure excellent outward folding capability.

[0036] The layers in the hardened film of this application embodiment will be described in detail below in a bottom-up order.

[0037] Substrate layer 110 In some embodiments of this application, the material of the substrate layer 110 includes at least one of polyethylene terephthalate (PET), cellulose triacetate (TAC), polycarbonate (PC), polyethylene (PE), polypropylene (PP), transparent polyimide (CPI), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), and polyethylene naphthalate (PEN). In some embodiments of this application, the thickness of the substrate layer 110 is 23~125μm, and can be 40~60μm.

[0038] In this embodiment, the material and thickness of the substrate layer 110 are set as described above, which can ensure the overall bending resistance.

[0039] First hardened layer 120 In some embodiments of this application, the components of the first curing liquid include, by weight, 100 parts of a first polyurethane acrylic resin; 3-10 parts of a photoinitiator; 200-400 parts of an organic solvent; 5-20 parts of a nanofiller; and 0.01-0.5 parts of a leveling agent.

[0040] In this embodiment, the first polyurethane acrylic resin used in the first curing liquid is a resin with good hardness and high functional groups. Its main function is to enhance the hardness of the first curing layer 120 and its adhesion to the substrate layer 110.

[0041] Second hardening layer 130 In some embodiments of this application, the absorption peak range of the blue light absorber in the second hardening liquid is 380~450nm; and / or, the blue light absorber includes at least one of cyanoacrylate blue light absorbers, benzotriazole blue light absorbers, and other organic blue light absorbers, and inorganic blue light absorbers such as cerium oxide. Specific materials that can be selected for blue light absorbers: Blue light absorbers are commercially available. The difference between them and the ultraviolet absorbers in the third hardened layer 140 is that they absorb different wavelengths. Blue light absorbers absorb blue light in the 380-450nm wavelength range, while ultraviolet absorbers absorb ultraviolet light below 380nm.

[0042] In some embodiments of this application, the components of the second hardening liquid include, by weight parts: 40-60 parts of the first polyurethane acrylic resin; 40-60 parts of the second polyurethane acrylic resin; 3-10 parts of the photoinitiator; 200-400 parts of the organic solvent; 5-20 parts of the nanofiller; 0.01-0.5 parts of the leveling agent; and 3-6 parts of the blue light absorber.

[0043] Third hardening layer 140 In some embodiments of this application, the third curing liquid further includes acrylate monomers, wherein the acrylate monomers include at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; and / or, the functionality of the acrylate monomers is ≥2.

[0044] In this embodiment, an acrylate monomer is added to the third hardening layer 140 for chemical bonding with the second hardening layer 130. The acrylate monomer has acrylate groups, which can connect the polymer chains in the second hardening layer 130 during curing. As an efficient crosslinking agent, it helps to form a highly crosslinked three-dimensional network structure, thereby increasing the adhesion between the third hardening layer 140 and the second hardening layer 130, so that the whole can have excellent bending performance.

[0045] In some embodiments of this application, the weight ratio of the ultraviolet absorber in the third curing liquid to the second polyurethane acrylic resin is (1~20):(60~80), or optionally (1~5):(60~80).

[0046] In some embodiments of this application, the absorption peak range of the ultraviolet absorber is 340~360nm; and / or, the ultraviolet absorber includes at least one of benzophenone-based ultraviolet absorbers and triazine-based ultraviolet absorbers.

[0047] Ultraviolet light absorbers are also called UV shielding agents or ultraviolet light blocking agents. This application does not impose specific limitations on ultraviolet light absorbers and can use conventional commercially available products.

[0048] In some embodiments of this application, the third curing liquid further includes a leveling agent, and the weight ratio of the leveling agent to the second polyurethane acrylic resin is (0.3~1):(60~80).

[0049] In this embodiment, the third hardening liquid also contains a specific mass ratio of leveling agent to control the water contact angle on the surface of the hardened layer, thereby ensuring its application effect.

[0050] In some embodiments of this application, the components of the third curing liquid include, by weight: 60-80 parts of the second polyurethane acrylic resin; 20-40 parts of acrylate monomer; 3-10 parts of photoinitiator; 200-400 parts of organic solvent; 5-20 parts of nanofiller; 0.3-1 part of leveling agent; and 1-20 parts of ultraviolet light absorber.

[0051] In some embodiments of this application, the photoinitiator includes α-aminoketones or acylphosphine oxides; And / or, the organic solvents include at least one of ethanol, isopropanol, butanol, acetone, butanone (MEK), cyclohexanone, ethyl acetate, butyl acetate, and dimethylacetamide; And / or, the nanofiller includes at least one of alumina, zinc oxide, and silica, with a particle size of 10 nm to 100 nm (the particle size can be selected as 20 to 50 nm). And / or, leveling agents include fluorinated acrylic compounds.

[0052] In this embodiment, the photoinitiator is selected from the aforementioned types to give each coating better optical properties. The organic solvents selected are butanone (MEK) and dimethylacetamide, a highly polar aprotic organic solvent, to ensure good interfacial adhesion between the coating and the substrate layer 110.

[0053] In some embodiments of this application, the hardness of the first hardened layer 120 is ≥2H, the thickness is ≤2μm, and the water contact angle of the first hardened layer 120 is 50~70°. The hardness of the second hardened layer 130 is ≥2H, the thickness is ≤1μm, and the water contact angle of the second hardened layer 130 is 50°~70°. The water contact angle of the third hardened layer 140 is 95~105°; The water contact angle of the hardened film is 95~105°, the elongation at break of the coating is >3%, the hardness is ≥2H, the bending performance meets the requirements of inner fold R1: 400,000 times, outer fold R2: 200,000 times, and the 400nm transmittance is ≤20%.

[0054] Inward folding is a physical phenomenon in which an object folds inward under the action of an external force, resulting in a change in shape. Inward folding R1: 400,000 times means that the hardened film can fold inward 400,000 times. Outward folding is a physical phenomenon in which an object folds outward under the action of an external force, resulting in a change in shape. Outward folding R2: 200,000 times means that the hardened film can fold outward 200,000 times.

[0055] In this embodiment, the parameter requirements for each layer and the whole are as follows: The first hardened layer 120 has requirements for hardness and thickness, with a pencil hardness greater than or equal to 2H and a coating thickness ≤ 2μm. To ensure adhesion between the second hardened layer 130 and the first hardened layer 120, the surface area of ​​the first hardened layer 120 cannot be too low. Therefore, the water contact angle of the first hardened layer 120 is between 50° and 70°. This design is to ensure the adhesion between the first hardened layer 120 and the second hardened layer 130 and to ensure excellent chemical bonding. The second hardened layer 130 has requirements for hardness, thickness, and surface water contact angle, with a hardness ≥ 2H and a coating thickness ≤ 2μm. The layer thickness is ≤1μm, and the water contact angle is between 50° and 70°. This design ensures the adhesion between the second hardening layer 130 and the first hardening layer 120 and the third hardening layer 140, ensuring excellent chemical bonding. The water contact angle of the third coating layer is between 95° and 105°, ensuring that the interfacial peel force between the protective film adhesive layer and the coating surface is ≥210g / mm, so as to reduce the possibility of air bubbles and delamination when bending the protective film and the film layer after the final product is applied. The elongation at break of the hardened film coating is >3%, and the flexibility design of the resin in different layers is used to meet the requirements of excellent inward and outward folding ability.

[0056] This application provides a foldable electronic product, which includes the hardened film described in the foregoing embodiments.

[0057] In this embodiment, the foldable electronic product has a foldable cover plate. The hardened film can be applied to the foldable cover plate of the foldable electronic product as a protective film, or it can be directly fabricated into the foldable cover plate. In one embodiment, the substrate layer of the hardened film is applied to the foldable cover plate via an OCA layer.

[0058] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0059] Example 1 This embodiment provides a hardened film, the preparation process of which is as follows: Preparation of the first curing liquid: The components of the first curing liquid, by weight, include: polyurethane acrylic resin with a functionality of 6-12: Qiaorun New Materials JR9915 (functionality of 9), 100 parts; photoinitiator: photoinitiator 907 (2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone), 4 parts; organic solvent: butanone (MEK), 200 parts + dimethylacetamide, 80 parts; nanofiller: alumina (BYK Chemical NANOBYK-3610), 20 parts; leveling agent: fluoroacrylic acid compound (Shin-Etsu Chemical KY-1203), 0.05 parts. The above components are mixed and stirred evenly to obtain the first curing liquid.

[0060] Preparation of the second curing liquid: The components of the second curing liquid, by weight, include: polyurethane acrylic resin with a functionality of 6-12: Qiaorun New Materials JR9915 (functionality of 9), 50 parts; second polyurethane acrylic resin: Zhanxin EBECRYL® 5129 (functionality of 6), 50 parts; photoinitiator: photoinitiator 907, 4 parts; organic solvent: methyl ethyl ketone (MEK), 200 parts + dimethylacetamide, 80 parts; nanofiller: alumina (BYK Chemical NANOBYK-3610), 10 parts; leveling agent: fluoroacrylate compound (Shin-Etsu Chemical KY-1203), 0.05 parts; blue light absorber: Qitai EXP-BLA-9546, 5 parts. The above components are mixed and stirred evenly to obtain the second curing liquid.

[0061] Preparation of the third curing liquid: The components of the third curing liquid, by weight, include: Second polyurethane acrylic resin: EBECRIL® 5129 (functionality 6), 80 parts; Acrylate monomer: 1,6-hexanediol diacrylate, 20 parts; Photoinitiator: Photoinitiator 907, 4 parts; Organic solvent: Butanone (MEK), 200 parts + dimethylacetamide, 80 parts; Nanofiller: Alumina (NANOBYK-3610), 10 parts; Leveling agent: Fluoroacrylate compound (Shin-Etsu Chemical KY-1203), 0.5 parts; Ultraviolet light absorber: Chiguard® GA403, 1.5 parts. Mix the above components evenly to obtain the third curing liquid.

[0062] Select a substrate layer (polyethylene terephthalate PET, 50 μm thick). First, apply a first curing liquid to one side of the substrate layer and cure to form a first cured layer with a thickness of 2 μm. Then, apply a second curing liquid and cure to form a second cured layer with a thickness of 1 μm. Next, apply a third curing liquid and cure to form a third cured layer with a thickness of 1 μm, resulting in a cured film with a thickness of 54 μm. This thickness was tested using a digital micrometer (CH-1-S): 3 sets of data were measured on the left, 3 sets in the middle, and 3 sets on the right, and the average value was taken.

[0063] Example 2 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the third hardening liquid, the leveling agent is 1 part of a fluoroacrylic acid compound (Shin-Etsu Chemical KY-1203), and the rest is the same as in Example 1. Finally, a hardened film is obtained.

[0064] Example 3 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the third hardening liquid, the leveling agent was 2 parts of a fluoroacrylic acid compound (Shin-Etsu Chemical KY-1203), and the rest were the same as in Example 1. Finally, a hardened film was obtained.

[0065] Example 4 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: The thickness of the hardened film is 56 μm, wherein the thickness of the first hardened layer is 2 μm, the thickness of the second hardened layer is 1 μm, the thickness of the third hardened layer is 3 μm, and the total thickness of the coating is 6 μm (greater than 4 μm). The rest is the same as in Example 1, and finally a hardened film is obtained.

[0066] Example 5 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the third hardening solution, no acrylate monomer was added, and the rest was the same as in Example 1, finally resulting in a hardened film.

[0067] Example 6 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the second curing liquid, the components include: 40 parts of the first polyurethane acrylic resin, 40 parts of the second polyurethane acrylic resin, 6 parts of the blue light absorber, and the rest are the same as in Example 1, and finally a curing film is obtained.

[0068] Example 7 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the second curing liquid, the components include: 60 parts of the first polyurethane acrylic resin, 60 parts of the second polyurethane acrylic resin, 3 parts of the blue light absorber, and the rest are the same as in Example 1, and finally a curing film is obtained.

[0069] Comparative Example 1 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the first curing liquid, use 100 parts of a polyurethane acrylic resin with a functionality of 1 to 6: EBECRIL® 5129 (functionality of 6), to replace the polyurethane acrylic resin with a functionality of 6 to 12. No blue light absorber is added when preparing the second hardening solution; No ultraviolet light absorber is added when preparing the third hardening solution; The rest is the same as in Example 1, and finally a hardened film is obtained.

[0070] Comparative Example 2 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the second hardening solution, 2 parts of blue light absorber: Qitai EXP-BLA-9546 were used, and the rest were the same as in Example 1. Finally, a hardened film was obtained.

[0071] Comparative Example 3 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the second hardening solution, 8 parts of blue light absorber: Qitai EXP-BLA-9546 were used, and the rest were the same as in Example 1. Finally, a hardened film was obtained.

[0072] Comparative Example 4 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the third hardening solution, no ultraviolet light absorber was added, and the rest was the same as in Example 1, finally resulting in a hardened film.

[0073] Comparative Example 5 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: When preparing the first hardening solution, a blue light absorber, Qitai EXP-BLA-9546, was also added in 5 parts. No blue light absorber is added when preparing the second hardening solution; The rest is the same as in Example 1, and finally a hardened film is obtained.

[0074] Comparative Example 6 This comparative example provides a hardened film, the preparation process of which differs from that of Example 1 in that: No blue light absorber is added when preparing the second hardening solution; When preparing the third hardening solution, a blue light absorber, Qitai EXP-BLA-9546, was added in 2 parts, and no ultraviolet light absorber was added. The rest was the same as in Example 1, and finally a hardened film was obtained.

[0075] Comparative Example 7 This embodiment provides a hardened film, the preparation process of which differs from that of Example 1 in that: No blue light absorber is added when preparing the second hardening solution; When preparing the third hardening solution, a blue light absorber, Qitai EXP-BLA-9546, was added in 5 parts, and no ultraviolet light absorber was added. The rest was the same as in Example 1, and finally a hardened film was obtained.

[0076] The performance of the hardened films of Examples 1-5 and Comparative Examples 1-7 was tested.

[0077] 1. 550nm transmittance The sample was cut into 40*40mm pieces, fixed on the sample stage, and tested using a Konica CM3600A spectrophotometer with the light path passing through the surface of the third hardened layer, using a D65 light source and a wavelength of 550nm. Five tests were performed and the average value was taken.

[0078] The pass rate is ≥90%.

[0079] II. Transmittance at 550nm after storage at high temperature and high humidity (60℃; 90%RH) for 240 hours The sample was cut into 40*40mm pieces and stored at 60℃ and 90%RH for 240h. Then it was taken out and left to stand at room temperature for 30min. The sample was fixed on the sample stage and tested with a Konica CM3600A spectrophotometer with the light path passing through the surface of the third hardened layer, a D65 light source, and a wavelength of 550nm. Five tests were performed and the average value was taken.

[0080] The pass rate is ≥90%.

[0081] III. 400nm transmittance The sample was cut into 40*40mm pieces, fixed on the sample stage, and tested using a Konica CM3600A spectrophotometer with the light path passing through the surface of the third hardened layer, using a D65 light source and a wavelength of 400nm. Five tests were performed and the average value was taken.

[0082] The pass rate is ≤20%.

[0083] IV. Adhesion at room temperature (100-cross test) Use a sharp blade (blade angle 20°~30°, blade thickness 0.43±0.03mm) to draw 10×10 1mm×1mm small grids on the surface of the test sample; Clean the test area with a brush, firmly stick the small grid to be tested with adhesive tape (NICHIBANCT405AP-24 tape) with an adhesion strength of (10±1) N / 25mm, and squeeze the tape with an eraser or your fingernail to remove air bubbles between the tape and the coating, so as to increase the contact area between the tape and the test area. After standing for (90±30) seconds, grasp one end of the tape and pull it off within 0.5 to 1 second at a 60° angle. Record the results of the first cross-cut adhesion test according to the judgment criteria. Then, firmly adhere the tape (NICHIBAN CT405AP-24 adhesive tape) to the test grid again, and squeeze the tape with an eraser or fingernail to remove air bubbles between the tape and the coating, thereby increasing the contact area between the tape and the test area. After standing for (90±30) seconds, grasp one end of the tape and pull it off within 0.5 to 1 second at a 60° angle. Record the results of the second cross-cut adhesion test according to the judgment criteria.

[0084] Judgment criteria: 5B: The gridded area remains completely intact; 4B: The area of ​​peeling off in the marked area is less than 5%; 3B: The area of ​​peeling off in the gridded areas is 5%~15%; 2B: The area of ​​peeling off in the gridded areas is 15%~35%; 1B: The area of ​​peeling off in the gridded areas is 35%~65%; 0B: The area of ​​peeling off in the gridded region is greater than 65%.

[0085] V. Surface water contact angle 1. Fix the sample to the water contact angle tester platform with double-sided tape, with the third hardened layer facing upwards, ensuring it is placed horizontally and flat.

[0086] 2. The droplet volume is 2uL. The test starts 30 seconds after the droplet timer begins and ends in 60 seconds.

[0087] 3. Take measurements at 9 different locations and record the range of water contact angle.

[0088] VI. Peel strength of OCA (FL9) and hardened film surface gf / 25mm (tested after standing at room temperature for 24 hours) A 25mm*200mm OCA sample was bonded to the third hardened layer and rolled three times with a 2KG roller. After standing at room temperature for 24 hours, the lower end of the sample was fixed with a tensile testing machine and the temperature was zeroed. The sample was then peeled at a speed of 300mm / min along a 180° direction. The average tensile force of the stable curve region for at least 70mm was recorded. The test was repeated 5 times, and the range of the 5 values ​​was recorded.

[0089] VII. Dynamic Inward Folding Room temperature dynamic inward folding test 1. Use double-sided tape to attach the substrate layer of the sample to the bending machine for testing. The third hardened layer should face upwards for the inward bending test.

[0090] 2. Bending machine settings: closing angle 0°, opening angle 180°, bending frequency 30 times / min, bending radius 1mm, test 10,000 to 500,000 times.

[0091] During the test, observe the area with a flashlight; if there is no whitening or cracks, the test is considered passed.

[0092] 8. Dynamic outward folding Room temperature dynamic outward folding test 1. Use double-sided tape to attach the third hardened layer of the sample to a bending machine for testing, with the substrate layer facing upwards for outward bending tests.

[0093] 2. Bending machine settings: closing angle 0°, opening angle 180°, bending frequency 30 times / min, bending radius 2mm, test 1000 to 200,000 times.

[0094] During the test, observe the area with a flashlight; if there is no whitening or cracks, the test is considered passed.

[0095] 9. OCA+PET-HC dynamic inward folding R1 test: 200,000 cycles; OCA+PET-HC dynamic inward folding R1 test: 400,000 cycles. OCA was bonded to the third hardened layer and rolled three times with a 2KG roller. After standing at room temperature for 24 hours, the dynamic inward folding of OCA+PET-HC was tested. The test method is the same as in item 5, "Dynamic Inward Folding". √ indicates that there is no delamination and no air bubbles between OCA and the third hardened layer, and × indicates that there is delamination or air bubbles between OCA and the third hardened layer.

[0096] The test results are shown in Table 1.

[0097] Table 1 Test results of different hardened films

[0098] Based on the results in Table 1, we can see that: The hardened films of Examples 1-5, in addition to meeting the basic optical performance requirements (the transmittance of the hardened film at 550nm under different conditions meets the qualified standard, and the adhesion at room temperature meets the qualified standard), not only have good bending resistance (the dynamic inward folding R1 of the hardened film itself reaches more than 100,000 times, and the dynamic outward folding R2 reaches more than 10,000 times), but also have excellent anti-blue light performance (the transmittance at 400nm meets the qualified standard).

[0099] As shown in Examples 1 (appropriate amount of leveling agent in the third hardening layer), 2 (slightly larger amount of leveling agent in the third hardening layer), and 3 (excessive amount of leveling agent in the third hardening layer), the amount of leveling agent in the third hardening layer affects the surface contact angle of the hardened film, thus affecting the peel force and bending performance after the hardened film is bonded to OCA. This is because the size of the surface water contact angle of the hardened film affects the change in adhesion after the hardened film is bonded to OCA. Specifically, in Example 1, an appropriate amount of leveling agent is added to the third hardening layer of the hardened film, resulting in a surface water contact angle between 95° and 105°, ensuring that the adhesion between the hardened film surface and OCA exceeds 210gf / 25mm. This guarantees that the hardened film will not delaminate after 200,000 or 400,000 bends after bonding to OCA. However, in Examples 2 and 3, an excessive amount of leveling agent is added to the hardened film, resulting in an excessively large surface water contact angle and insufficient adhesion between the hardened film and OCA (less than 210gf / 25mm), making delamination easy after bending.

[0100] As shown in Examples 1 (total coating thickness equal to 4 μm) and 4 (total coating thickness greater than 4 μm), the total coating thickness affects the bending ability of the hardened film itself, because the bending ability gradually weakens as the coating thickness increases. Specifically, the hardened film of Example 1 exhibits excellent inward and outward folding capabilities, while the hardened film of Example 4 shows a decrease in both inward and outward folding capabilities as the coating thickness increases.

[0101] According to Example 1 (the third hardening layer contains acrylate monomers) and Example 5 (the third hardening layer does not contain active monomers), adding acrylate monomers to the third hardening layer can significantly improve the bending performance of the hardened film and also improve the room temperature adhesion of the hardened film to a certain extent. This is because adding active monomers to the third hardening layer can improve the interfacial adhesion, thereby improving the overall bending ability.

[0102] The hardened films of Comparative Examples 1 to 7 could not simultaneously meet the basic optical performance requirements while also achieving good bending resistance and excellent blue light resistance.

[0103] In Comparative Example 1, the first hardening layer did not use a specific resin, but a resin with better toughness. The second hardening layer did not contain a blue light absorber, and the third hardening layer did not contain a violet light absorber. This resulted in poor adhesion and bending ability of the first hardening film, and it did not have excellent anti-blue light performance.

[0104] In Comparative Example 2, the amount of blue light absorber in the second hardening layer was too small, and the corresponding hardening film did not have excellent anti-blue light performance; in Comparative Example 3, the amount of blue light absorber in the second hardening layer was too large, and the corresponding hardening film did not meet the qualified standard for 550nm transmittance after high temperature and high humidity, that is, it did not have high temperature and high humidity optical performance.

[0105] In Comparative Example 4, no ultraviolet light absorber was added to the third hardening layer, and the corresponding hardened film did not have excellent anti-blue light performance (the 400nm transmittance did not meet the qualified standard). This shows that the absence of ultraviolet light absorber in the third hardening layer will affect the anti-blue light effect. This is because adding a blue light absorber to the second hardening layer and adding an appropriate amount of ultraviolet light absorber to the third hardening layer will block some ultraviolet light when visible light passes through the third hardening layer, thus ensuring that the entire film layer has excellent anti-blue light effect.

[0106] In Comparative Example 5, a blue light absorber was added to the first hardened layer, but no blue light absorber was added to the second hardened layer. Consequently, the room temperature adhesion of the hardened film was significantly worse, and the bending performance was also significantly worse. This shows that adding a blue light absorber to the first hardened layer will affect the adhesion and thus the bending performance.

[0107] In Comparative Example 6, no blue light absorber was added to the second hardening layer, but a small amount of blue light absorber was added to the third hardening layer, and no ultraviolet light absorber was added. The corresponding hardened film had poor anti-blue light effect. In Comparative Example 7, no blue light absorber was added to the second hardening layer, but a large amount of blue light absorber was added to the third hardening layer, and no ultraviolet light absorber was added. The corresponding hardened film did not meet the qualified standard for 550nm transmittance after high temperature and high humidity. This is because a large amount of blue light absorber needs to be added to the third hardening layer to achieve excellent anti-blue light effect. However, the blue light absorber in the third hardening layer on the film surface is prone to precipitation, affecting the overall optical performance. Therefore, a third hardening layer needs to be set on the second hardening layer with added blue light absorber to avoid the precipitation problem of blue light absorber on the film surface.

[0108] In summary, the hardened film and foldable electronic product of this application embodiment have good blue light resistance while ensuring good bending resistance.

[0109] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A hardened film, characterized in that, It includes a substrate layer, and a first hardening layer, a second hardening layer and a third hardening layer sequentially stacked on the substrate layer; Wherein, the first curing liquid corresponding to the first curing layer includes a first polyurethane acrylic resin; The second curing liquid corresponding to the second curing layer contains a first polyurethane acrylic resin, a second polyurethane acrylic resin, and a blue light absorber. The weight ratio of the first polyurethane acrylic resin, the second polyurethane acrylic resin, and the blue light absorber in the second curing liquid is (40~60):(40~60):(3~6). The third curing liquid corresponding to the third curing layer contains a second polyurethane acrylic resin and an ultraviolet light absorber; The first polyurethane acrylic resin has a functionality of 6 to 12, the second polyurethane acrylic resin has a functionality of 1 to 6, and the functionality of the first polyurethane acrylic resin is greater than that of the second polyurethane acrylic resin.

2. The hardened film according to claim 1, characterized in that, The third curing liquid further includes acrylate monomers, wherein the acrylate monomers include at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; and / or, the functionality of the acrylate monomers is ≥2. And / or, the weight ratio of the ultraviolet absorber to the second polyurethane acrylic resin in the third hardening liquid is (1~20):(60~80); And / or, the third hardening liquid further includes a leveling agent, and the weight ratio of the leveling agent to the second polyurethane acrylic resin is (0.3~1):(60~80).

3. The hardened film according to claim 1, characterized in that, The components of the third hardening liquid, by weight, include: 60-80 parts of the second polyurethane acrylic resin; 20-40 parts of acrylate monomer; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.3~1 part; 1-20 parts of ultraviolet light absorber.

4. The hardened film according to claim 1, characterized in that, The absorption peak range of the blue light absorber in the second hardening liquid is 380~450nm; and / or, the blue light absorber includes at least one of cyanoacrylate blue light absorbers, benzotriazole blue light absorbers, and cerium oxide.

5. The hardened film according to claim 1, characterized in that, The components of the second hardening liquid, by weight, include: 40-60 parts of the first polyurethane acrylic resin; 40-60 parts of the second polyurethane acrylic resin; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.01~0.5 parts; 3-6 parts of blue light absorber.

6. The hardened film according to claim 1, characterized in that, The components of the first hardening liquid, by weight, include: 100 parts of the first polyurethane acrylic resin; 3-10 parts of photoinitiator; Organic solvent 200-400 parts; 5-20 parts of nanofiller; Leveling agent 0.01~0.5 parts.

7. The hardened film according to claim 3, 5 or 6, characterized in that, The photoinitiator includes α-amino ketones or acylphosphine oxides; And / or, the organic solvent includes at least one of ethanol, isopropanol, butanol, acetone, butanone, cyclohexanone, ethyl acetate, butyl acetate, and dimethylacetamide; And / or, the nanofiller includes at least one of alumina, zinc oxide, and silicon dioxide, with a particle size of 10 nm to 100 nm; And / or, the leveling agent includes a fluorinated acrylic compound.

8. The hardened film according to claim 1, characterized in that, The total thickness of the first hardened layer, the second hardened layer, and the third hardened layer is ≤4μm; And / or, the material of the substrate layer includes at least one of polyethylene terephthalate, cellulose triacetate, polycarbonate, polyethylene, polypropylene, transparent polyimide, polymethyl methacrylate, thermoplastic polyurethane, and polyethylene naphthalate. And / or, the thickness of the substrate layer is 23~125μm.

9. The hardened film according to claim 1, characterized in that, The hardness of the first hardened layer is ≥2H, the thickness is ≤2μm, and the water contact angle of the first hardened layer is 50~70°. And / or, the hardness of the second hardened layer is ≥2H, the thickness is ≤1μm, and the water contact angle of the second hardened layer is 50°~70°; And / or, the water contact angle of the third hardened layer is 95~105°; And / or, the water contact angle of the hardened film is 95~105°, the elongation at break of the coating is >3%, the hardness is ≥2H, and the transmittance at 400nm is ≤20%.

10. A foldable electronic product, characterized in that, It includes the hardened film as described in any one of claims 1 to 9.

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