A high-temperature deformation and warping resistant brightening film

Abstract

An optical film resistant to high-temperature warping deformation is disclosed. The optical film includes a substrate layer, an optical layer, and a protective layer. The adhesive layer has a certain degree of resilience and can provide a pull-back force when the optical layer deforms due to heat, thereby reducing the warping height and preventing the film from warping significantly due to temperature. This solves the technical problem of high-temperature deformation and warping of the brightness enhancement film, while ensuring its excellent optical performance.

Description

Technical Field

[0001] This invention relates to optical thin films, belonging to the field of optical displays, and specifically to a brightness enhancement film resistant to high-temperature deformation and warping. Background Technology

[0002] Brightness enhancement films are categorized into general prism sheets, multi-functional prism sheets, and reflective polarizers. Among these, reflective polarizers currently offer the best improvement in luminous efficiency, increasing it by at least 30% compared to other similar products. Reflective polarizers control light intensity distribution through refraction, total internal reflection, and light accumulation of incident light, and also recycle unused light outside the viewing angle through reflection, reducing light loss and improving overall brightness and uniformity. Furthermore, combining different material layers can further enhance its performance.

[0003] However, the shrinkage rates of the optical layer and the PET substrate layer in reflective polarizing film differ significantly. During transportation and storage, the film can deform and warp due to high temperatures. Warped brightening film is detrimental to subsequent assembly, often resulting in problems such as white spots, black shadows, and poor adhesion, leading to a decrease in overall image quality.

[0004] Chinese patent 201811650248.7 discloses an anti-warping optical base film, which counteracts warping caused by composite film shrinkage by adding a transparent support and a stress absorption layer. This method increases the thickness of the composite film, which contradicts the current trend of large-size and thin displays. Furthermore, the added transparent support may reduce the overall brightness of the device.

[0005] Chinese Patent 202110825242.4 discloses a warp-resistant composite brightening film, comprising a substrate layer, a main prism layer, a sub-prism layer, and a surface layer. The main prism layer is disposed at the upper end of the substrate layer, the surface layer is bonded above the main prism layer, and the sub-prism layer is disposed between the surface layer and the main prism layer. This patent uses a complex main prism layer and sub-prism layer structure, and its warp resistance is generally poor.

[0006] Chinese Patent 201811466866.6 discloses an anti-warping optical brightening film, which sequentially comprises a first substrate layer, an adhesive layer, and a second substrate layer. The upper surface of the first substrate layer has a prism layer, and the lower surface of the second substrate layer has a protective layer. The adhesive layer is formed by a coating composition comprising 40%-60% acrylate oligomer, 20%-30% monomer, 1.2%-4.5% photoinitiator, and 5.5%-38.8% diluent, all percentages being by weight. This patent employs a multi-layer optical layer bonding method, resulting in numerous layers and a complex process. Furthermore, during the bonding process, the prism peaks inevitably penetrate the adhesive layer too deeply, leading to a decrease in the brightness of the composite brightening film.

[0007] Chinese Patent 201611113489.9 discloses a novel multifunctional optical composite film, comprising: at least one diffusion film or microlens film; and at least one brightness enhancement film; wherein the diffusion film and the brightness enhancement film are bonded together by an adhesive. This patent prepares the composite film by laminating multiple functional films, a complex lamination process.

[0008] In summary, researching and preparing a composite film with excellent optical properties and good anti-warping properties has become a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0009] To address the technical problem of high-temperature deformation and warping of brightness enhancement films while ensuring their excellent optical performance, this invention provides a brightness enhancement film that can resist deformation and warping at a high temperature of 50°C. To solve the aforementioned technical problem, this invention adopts the following technical solution.

[0010] This invention first provides an optical thin film resistant to high-temperature warping deformation. The optical thin film includes a substrate layer, an optical layer, and a protective layer. The thickness of the substrate layer is between 50-150 μm, and the thickness of the optical layer is between 50-100 μm. Both the substrate layer and the optical layer are coated with an anti-glare coating liquid. An adhesive layer is provided between the substrate layer and the optical layer, and the thickness of the adhesive layer is between 2-25 μm. The protective layer contains an inorganic material with good thermal conductivity, and the thickness of the protective layer is between 5-20 μm.

[0011] Furthermore, the substrate layer is selected from PET substrate, and the thickness of the PET substrate is between 75-125μm, or the thickness of the PET substrate is 80μm, 90μm, 100μm, 110μm, or 120μm.

[0012] Furthermore, the back of the PET substrate is coated with an anti-glare coating liquid, resulting in a haze between 35% and 45%, or a haze of 38%, 40%, or 42%. This design improves the light source utilization rate of the brightness enhancement film and protects the optical layer, enhancing its abrasion resistance. According to embodiments of the present invention, a comparison of luminance gain shows that this film has a better light source utilization rate than other films.

[0013] Furthermore, the anti-glare coating liquid includes a deca-functional polyurethane acrylic resin oligomer, a hexa-functional acrylic monomer, a photoinitiator, a leveling agent, silica anti-glare particles, polymethyl methacrylate, and an organic solvent.

[0014] Furthermore, the anti-glare coating liquid comprises 25%-35% decafunctional polyurethane acrylic resin oligomer, 10%-20% hexafunctional acrylic monomer, 2%-10% photoinitiator, 0.1%-2% leveling agent, 0.2%-3% silica anti-glare particles, 0.1%-2% polymethyl methacrylate, and 40%-60% organic solvent.

[0015] Furthermore, the optical layer is selected as a core layer, which is a reflective polarizing brightening film.

[0016] Furthermore, the core layer coating particles are the same particles or a mixture of multiple particles used in the PET substrate back coating, with a haze between 30% and 40%, or a haze of 32%, 35%, or 38%.

[0017] Furthermore, the core layer is a multilayer film of polyethylene terephthalate and its copolymers.

[0018] Furthermore, the particulate material coated on the surface of the PET substrate layer and the optical layer is one or a mixture of PMMA (polymethyl methacrylate), silicone, PA (polyamide) and / or PU (polyester).

[0019] Furthermore, the adhesive layer is located between the core layer and the PET substrate layer, and the thickness of the adhesive layer is between 5-15 μm, or 8 μm, 10 μm, or 12 μm.

[0020] Furthermore, the adhesive layer comprises an adhesive monomer isoborneol acrylate, an acrylic resin oligomer, bisphenol A diacrylate, an reactive diluent β-hydroxyethyl methacrylate, a photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and an ionomer gel.

[0021] Furthermore, the adhesive layer comprises 20%-30% of the bonding monomer isoborneol acrylate, 35%-45% of acrylic resin oligomer, 16%-20% of bisphenol A diacrylate, 5%-10% of the reactive diluent β-hydroxyethyl methacrylate, 0.5%-1.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 5%-8% of ionomer gel.

[0022] Furthermore, the content of the adhesive layer is 22%, 24%, 26%, or 28%.

[0023] Furthermore, the content of the acrylic resin oligomer is 38%, 40%, or 42%.

[0024] Furthermore, the content of the bisphenol A diacrylate is 17%, 18%, or 19%.

[0025] Furthermore, the content of the diluent β-hydroxyethyl methacrylate is 6%, 8%, or 9%.

[0026] Furthermore, the content of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone is 0.7%, 0.9%, and 1.2%.

[0027] Furthermore, the content of the ionogel is 6% or 7%. As a solid mixture with ionic conductivity, the ionogel can further improve the flexibility of the adhesive due to the interconnected and entangled polymer molecular chains.

[0028] Furthermore, the upper surface of the core layer is covered with a protective film, and the upper surface of the protective film has a mesh-like indentation with micropores distributed within the indentation. The pore size of the micropores ranges from 200 to 500 μm.

[0029] Furthermore, the pore size range of the micropores is 240μm, 260μm, 280μm, 300μm, 340μm, 380μm, 440μm, and 480μm.

[0030] Furthermore, the protective layer comprises a thermoplastic elastomer, silicone rubber, cellulose derivatives, thickeners, and titanium dioxide.

[0031] Furthermore, the protective layer comprises 10-20 parts of thermoplastic elastomer, 25-35 parts of silicone rubber, 5-10 parts of cellulose derivative, 10-15 parts of thickener, and 1-5 parts of titanium dioxide. These raw materials are coated onto the upper surface of the core layer using a roll-to-roll coating process in a specific ratio. Titanium dioxide has good thermal conductivity, absorbing heat from the core layer and then transferring it to the outside through the network gaps within the protective film.

[0032] Furthermore, the thickness of the protective layer is in the range of 6-15 μm, or 7 μm, 9 μm, 11 μm, or 13 μm.

[0033] This invention also provides a method for preparing an optical thin film resistant to high-temperature warping deformation, the method comprising the following steps:

[0034] Step (1) Preparation of anti-glare coating liquid: The decafunctional polyurethane acrylic resin oligomer, hexafunctional acrylic monomer, photoinitiator, leveling agent, silica anti-glare particles, polymethyl methacrylate and organic solvent are thoroughly stirred to obtain the anti-glare coating liquid.

[0035] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to the substrate layer and optical layer by using a roller coating method, and then dried and cured;

[0036] Step (3) Preparation of bonding adhesive layer: Stir and mix the bonding monomer isobornyl acrylate, acrylic resin oligomer, bisphenol A diacrylate, reactive diluent, ion gel, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone until uniform.

[0037] Step (4) Lamination: Apply the bonding adhesive material between the substrate layer and the optical layer, laminate, extrude and shape, and cure;

[0038] Step (5) Apply protective layer: Apply a protective layer consisting of thermoplastic elastomer, silicone rubber, cellulose derivative, thickener and titanium dioxide to the upper surface of the optical layer and cure it.

[0039] Furthermore, the drying temperature in step (2) is 30-80℃, and the drying process is gradient drying.

[0040] Furthermore, the curing in step (2) is carried out at 60 mJ / cm 2 -90mJ / cm 2 UV energy curing.

[0041] Further, in step (5), a protective layer is applied to the surface of the optical layer using a roll-to-roll coating process.

[0042] Furthermore, step (5) involves adhesive coating using structural rollers.

[0043] Furthermore, the drying temperature in step (4) is 30-80℃, and the drying process is gradient drying.

[0044] Furthermore, the substrate layer is selected from PET substrate, and the thickness of the PET substrate is between 75-125μm, or the thickness of the PET substrate is 80μm, 90μm, 100μm, 110μm, or 120μm.

[0045] Furthermore, the back of the PET substrate is coated with an anti-glare coating liquid, with a haze between 35% and 45%, or a haze of 38%, 40%, or 42%.

[0046] Furthermore, the anti-glare coating liquid includes a deca-functional polyurethane acrylic resin oligomer, a hexa-functional acrylic monomer, a photoinitiator, a leveling agent, silica anti-glare particles, polymethyl methacrylate, and an organic solvent.

[0047] Furthermore, the anti-glare coating liquid comprises 25%-35% decafunctional polyurethane acrylic resin oligomer, 10%-20% hexafunctional acrylic monomer, 2%-10% photoinitiator, 0.1%-2% leveling agent, 0.2%-3% silica anti-glare particles, 0.1%-2% polymethyl methacrylate, and 40%-60% organic solvent.

[0048] Furthermore, the optical layer is selected as a core layer, which is a reflective polarizing brightening film.

[0049] Furthermore, the core layer coating particles are the same particles or a mixture of multiple particles used in the PET substrate back coating, with a haze between 30% and 40%, or a haze of 32%, 35%, or 38%.

[0050] Furthermore, the core layer is a multilayer film of polyethylene terephthalate and its copolymers.

[0051] Furthermore, the particulate material coated on the surface of the PET substrate layer and the optical layer is one or a mixture of PMMA (polymethyl methacrylate), silicone, PA (polyamide) and / or PU (polyester).

[0052] Furthermore, the adhesive layer is located between the core layer and the PET substrate layer, and the thickness of the adhesive layer is between 5-15 μm, or 8 μm, 10 μm, or 12 μm.

[0053] Furthermore, the adhesive layer comprises an adhesive monomer isoborneol acrylate, an acrylic resin oligomer, bisphenol A diacrylate, an reactive diluent β-hydroxyethyl methacrylate, a photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and an ionomer gel.

[0054] Furthermore, the adhesive layer comprises 20%-30% of the bonding monomer isoborneol acrylate, 35%-45% of acrylic resin oligomer, 16%-20% of bisphenol A diacrylate, 5%-10% of the reactive diluent β-hydroxyethyl methacrylate, 0.5%-1.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 5%-8% of ionomer gel.

[0055] Furthermore, the content of the adhesive layer is 22%, 24%, 26%, or 28%.

[0056] Furthermore, the content of the acrylic resin oligomer is 38%, 40%, or 42%.

[0057] Furthermore, the content of the bisphenol A diacrylate is 17%, 18%, or 19%.

[0058] Furthermore, the content of the diluent β-hydroxyethyl methacrylate is 6%, 8%, or 9%.

[0059] Furthermore, the content of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone is 0.7%, 0.9%, and 1.2%.

[0060] Furthermore, the content of the ion gel is 6% or 7%.

[0061] Furthermore, the upper surface of the core layer is covered with a protective film, and the upper surface of the protective film has a mesh-like indentation with micropores distributed within the indentation. The pore size of the micropores ranges from 200 to 500 μm.

[0062] Furthermore, the pore size range of the micropores is 240μm, 260μm, 280μm, 300μm, 340μm, 380μm, 440μm, and 480μm.

[0063] Furthermore, the protective layer comprises a thermoplastic elastomer, silicone rubber, cellulose derivatives, thickeners, and titanium dioxide.

[0064] Furthermore, the protective layer comprises 10-20 parts of thermoplastic elastomer, 25-35 parts of silicone rubber, 5-10 parts of cellulose derivative, 10-15 parts of thickener and 1-5 parts of titanium dioxide, and the raw materials are coated on the upper surface of the core layer in a certain proportion using a roll-to-roll coating process.

[0065] Compared with the prior art, the product provided by this invention has a certain degree of elasticity in the adhesive layer. When the core layer deforms due to heat, it can provide a pull-back force, reduce the warpage height, and prevent the film from warping significantly due to temperature. At the same time, the protective film on the surface of the core layer can provide a certain degree of protection, preventing the core layer from being damaged during transportation and conveying, thus affecting the quality in subsequent use. In addition, the mesh-like indentations on the upper surface of the protective layer increase the specific surface area, which can provide a certain degree of heat dissipation capacity to the core layer and reduce the impact of temperature changes. Attached Figure Description

[0066] Figure 1 A schematic diagram of a brightness enhancement film;

[0067] Figure 2 This is a schematic diagram of the upper surface of the protective film;

[0068] Figure 3 This is a photograph of the actual sample from Example 1. Detailed Implementation

[0069] To better understand the structure, functional features, and advantages of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

[0070] 1. Haze test: Refer to GB / T 25273-2010 "Method for determination of haze of thin film for liquid crystal display (LCD) by integrating sphere method" to test the haze of each substrate after the back coating is applied.

[0071] 2. Peel strength test: Refer to GB / T 25256-2010 "Test method for 180° peel strength and residual adhesion of optical functional film release film" to test the peel strength between the optical layer of different films and the PET substrate layer.

[0072] 3. Abrasion resistance test: Use an abrasion testing machine with a load of 500g to test the abrasion resistance performance.

[0073] 4. Thickness test: Use a micrometer to test the thickness of the diaphragm.

[0074] 5. Brightness test: Using a specific backlight, place a test film and use a handheld grayscale meter to test its brightness.

[0075] 6. Brightness gain test: Using a specific backlight, test the brightness of a diffuser film as L0, and then test the brightness of the same diffuser film + optical enhancement film as L1. The brightness gain is L1 / L0.

[0076] 7. Shrinkage test: Use a 2.5D measuring instrument to measure the lengths A1, B1, C1, and D1 of the four sides of the film. Then place the film in a 60℃ oven for 30 minutes, and measure the lengths A2, B2, C2, and D2 of the four sides again. (A1-A2) / A1 is the shrinkage rate. The calculation method for other sides is the same.

[0077] 8. Warpage test: Cut the optical brightening film to be tested into A4 size, then place it in a 60℃ oven for 5 hours, and then let it cool naturally to room temperature. Take out the film and place it on a horizontal marble table, and measure the warpage height h.

[0078] The preferred embodiments of the present invention are described below. These preferred embodiments are for illustration and explanation only and are not intended to limit the present invention.

[0079] like Figure 1 As shown, the present invention provides a brightness enhancement film that can resist high-temperature deformation and warping. The optical film that can resist high-temperature deformation and warping includes, in sequence, a PET substrate layer 1, an adhesive layer 2, an optical layer 3, and a protective layer 4.

[0080] Example 1

[0081] A high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer, in sequence. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 80 μm for the PET substrate layer, 16 μm for the adhesive layer, 65 μm for the optical layer, and 6 μm for the protective film layer.

[0082] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0083] Step (1) Preparation of anti-glare coating liquid: 29.3% of decafunctional polyurethane acrylic resin oligomer, 14.7% of hexafunctional acrylic monomer, 4.9% of photoinitiator, 0.5% of leveling agent, 1.2% of silica anti-glare particles, 1.1% of polymethyl methacrylate and 48.3% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0084] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 125μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then subjected to a heat treatment of 80mJ / cm². 2 Curing is performed using UV energy;

[0085] Step (3) Preparation of the bonding adhesive layer: 25% of the bonding monomer isoborneol acrylate, 45% of the acrylic resin oligomer, 15% of bisphenol A diacrylate, 8% of the reactive diluent, 6.5% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0086] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0087] Step (5) Coating the protective layer: Mix 20 parts of thermoplastic elastomer, 25 parts of silicone rubber, 6 parts of cellulose derivative, 11 parts of thickener and 2 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0088] Example 2

[0089] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 80 μm for the PET substrate layer, 17 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0090] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0091] Step (1) Preparation of anti-glare coating liquid: 28.3% of decafunctional polyurethane acrylic resin oligomer, 14.5% of hexafunctional acrylic monomer, 4.5% of photoinitiator, 0.5% of leveling agent, 1.2% of silica anti-glare particles, 1.1% of polymethyl methacrylate and 49.9% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0092] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 125μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then subjected to a heat treatment of 80mJ / cm². 2 Curing is performed using UV energy;

[0093] Step (3) Preparation of the bonding adhesive layer: 22% of the bonding monomer isoborneol acrylate, 48% of the acrylic resin oligomer, 15% of bisphenol A diacrylate, 8.3% of the reactive diluent, 6.2% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0094] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0095] Step (5) Coating the protective layer: Mix 21 parts of thermoplastic elastomer, 25 parts of silicone rubber, 7 parts of cellulose derivative, 11 parts of thickener and 2 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0096] Example 3

[0097] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 80 μm for the PET substrate layer, 16 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0098] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0099] Step (1) Preparation of anti-glare coating liquid: 30.3% of decafunctional polyurethane acrylic resin oligomer, 13.5% of hexafunctional acrylic monomer, 3.5% of photoinitiator, 0.8% of leveling agent, 1.5% of silica anti-glare particles, 1.5% of polymethyl methacrylate and 48.9% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0100] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 125μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then subjected to a heat treatment of 80mJ / cm². 2 It is cured by UV energy.

[0101] Step (3) Preparation of the bonding adhesive layer: 25% of the bonding monomer isoborneol acrylate, 41% of the acrylic resin oligomer, 19% of bisphenol A diacrylate, 8.1% of the reactive diluent, 6.2% of the ion gel, and 0.7% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0102] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0103] Step (5) Coating the protective layer: Mix 21 parts of thermoplastic elastomer, 25 parts of silicone rubber, 7 parts of cellulose derivative, 11 parts of thickener and 2 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0104] Example 4

[0105] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 80 μm for the PET substrate layer, 19 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0106] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0107] Step (1) Preparation of anti-glare coating liquid: 27.8% of decafunctional polyurethane acrylic resin oligomer, 14.5% of hexafunctional acrylic monomer, 5.5% of photoinitiator, 1.0% of leveling agent, 1.1% of silica anti-glare particles, 1.3% of polymethyl methacrylate and 48.8% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0108] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 125μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then subjected to a heat treatment of 80mJ / cm². 2 Curing is performed using UV energy;

[0109] Step (3) Preparation of the bonding adhesive layer: 40% of the bonding monomer isoborneol acrylate, 28% of the acrylic resin oligomer, 17% of bisphenol A diacrylate, 8.3% of the reactive diluent, 6.2% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0110] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0111] Step (5) Coating the protective layer: Mix 23 parts of thermoplastic elastomer, 25 parts of silicone rubber, 7 parts of cellulose derivative, 11 parts of thickener and 3 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and then bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0112] Example 5

[0113] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 131 μm for the PET substrate layer, 21 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0114] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0115] Step (1) Preparation of anti-glare coating liquid: 35.2% of decafunctional polyurethane acrylic resin oligomer, 12.5% ​​of hexafunctional acrylic monomer, 4.5% of photoinitiator, 1.5% of leveling agent, 1.5% of silica anti-glare particles, 1.2% of polymethyl methacrylate and 43.6% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0116] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 125μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then subjected to a heat treatment of 80mJ / cm². 2 It is cured by UV energy.

[0117] Step (3) Preparation of the bonding adhesive layer: 22% of the bonding monomer isoborneol acrylate, 48% of the acrylic resin oligomer, 15% of bisphenol A diacrylate, 8.5% of the reactive diluent, 6% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0118] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0119] Step (5) Coating the protective layer: Mix 25 parts of thermoplastic elastomer, 25 parts of silicone rubber, 7 parts of cellulose derivative, 11 parts of thickener and 3 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and adhere and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0120] Example 6

[0121] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 130 μm for the PET substrate layer, 18 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0122] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0123] Step (1) Preparation of anti-glare coating liquid: 31.3% of decafunctional polyurethane acrylic resin oligomer, 11.5% of hexafunctional acrylic monomer, 3.5% of photoinitiator, 1.7% of leveling agent, 1.8% of silica anti-glare particles, 1.4% of polymethyl methacrylate and 48.8% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0124] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 75μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then applied at 80mJ / cm². 2 Curing is performed using UV energy;

[0125] Step (3) Preparation of the bonding adhesive layer: 23% of the bonding monomer isoborneol acrylate, 47% of the acrylic resin oligomer, 15% of bisphenol A diacrylate, 8.4% of the reactive diluent, 6.1% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0126] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0127] Step (5) Coating the protective layer: Mix 25 parts of thermoplastic elastomer, 22 parts of silicone rubber, 8 parts of cellulose derivative, 11 parts of thickener and 4 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and then bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0128] Example 7

[0129] The high-temperature warping resistant brightening film is composed of a PET substrate layer, an adhesive layer, an optical layer, and a protective layer. Both the PET substrate layer and the optical layer have a protective coating on top, and the optical layer has a protective layer on top of it. The thicknesses of each layer are: 131 μm for the PET substrate layer, 22 μm for the adhesive layer, 65 μm for the optical layer, and 7 μm for the protective film layer.

[0130] The preparation method of the high-temperature warpage-resistant brightening film includes the following steps:

[0131] Step (1) Preparation of anti-glare coating liquid: 27.3% of decafunctional polyurethane acrylic resin oligomer, 14.5% of hexafunctional acrylic monomer, 3.3% of photoinitiator, 1.1% of leveling agent, 1.2% of silica anti-glare particles, 1.5% of polymethyl methacrylate and 51.1% of organic solvent ethyl acetate are thoroughly stirred to obtain anti-glare coating liquid;

[0132] Step (2) Coating liquid application: The anti-glare coating liquid obtained above is applied to a 75μm thick high-transparency PET substrate and a 60μm thick core layer using a roller coating method. After drying the coating in a gradient oven at 40℃, 50℃, and 60℃, the coating is then applied at 80mJ / cm². 2 Curing is performed using UV energy;

[0133] Step (3) Preparation of the bonding adhesive layer: 27% of the bonding monomer isoborneol acrylate, 43% of the acrylic resin oligomer, 15% of bisphenol A diacrylate, 8.5% of the reactive diluent, 6% of the ion gel, and 0.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are stirred in a mixing tank for 2 hours and mixed evenly.

[0134] Step (4) Lamination: The bonding adhesive material is fed into the pipeline and applied between the core layer and the PET substrate through the feed port. The optical layer (core layer) is then bonded to the PET substrate using this bonding adhesive. The film is then shaped by pressing with two pressure rollers to control the film thickness, and a 150mJ / cm² pressure is applied. 2 Cured by UV lamp irradiation;

[0135] Step (5) Coating the protective layer: Mix 25 parts of thermoplastic elastomer, 22 parts of silicone rubber, 8 parts of cellulose derivative, 11 parts of thickener and 4 parts of titanium dioxide in proportion, coat the core layer with a roll-to-roll coating process, and then bond and protect it under the pressure of the structural roller to build the structure of the upper surface of the protective film. Finally, heat cure it in a gradient oven at 40℃, 50℃, 50℃ and 40℃.

[0136] Comparative Example 1:

[0137] The difference from Example 1 is that the core layer of this comparative example does not have a protective film on its upper surface. The adhesive formulation of this comparative example is as follows: 5 parts by weight of 3(ethoxy)bisphenol A di(meth)acrylate; 62 parts by weight of 3(ethoxy)trimethylolpropane trimethacrylate; 30 parts by weight of polyurethane acrylic resin; 3 parts by weight of 2-hydroxy-methylphenylpropane-1-one (1173); and 0.4 parts by weight of additives. The PET substrate layer is 80 μm thick, the adhesive layer is 15 μm thick, and the optical layer is 65 μm thick.

[0138] Comparative Example 2:

[0139] The difference from Example 1 is that the core layer of this comparative example does not have a protective film on its upper surface. The adhesive formulation of this comparative example is as follows: 5.5 parts by weight of 3(ethoxy)bisphenol A di(meth)acrylate; 60 parts by weight of 3(ethoxy)trimethylolpropane trimethacrylate; 30 parts by weight of polyurethane acrylic resin; 3 parts by weight of 2-hydroxy-methylphenylpropane-1-one (1173); and 0.4 parts by weight of additives. The PET substrate layer is 80 μm thick, the adhesive layer is 20 μm thick, and the optical layer is 65 μm thick.

[0140] Comparative Example 3:

[0141] The difference from Example 5 is that the core layer of this comparative example does not have a protective film on its upper surface. The adhesive formulation of this comparative example is as follows: 5 parts by weight of 3(ethoxy)bisphenol A di(meth)acrylate; 62 parts by weight of 3(ethoxy)trimethylolpropane trimethacrylate; 30 parts by weight of polyurethane acrylic resin; 3 parts by weight of 2-hydroxy-methylphenylpropane-1-one (1173); and 0.4 parts by weight of additives. The PET substrate layer is 131 μm thick, the adhesive layer is 21 μm thick, and the optical layer is 65 μm thick.

[0142] Comparative Example 4:

[0143] The difference from Example 1 is that the core layer of this comparative example does not have a protective film on its upper surface. The adhesive formulation of this comparative example is as follows: 5 parts by weight of 3(ethoxy)bisphenol A di(meth)acrylate; 62 parts by weight of 3(ethoxy)trimethylolpropane trimethacrylate; 30 parts by weight of polyurethane acrylic resin; 3 parts by weight of 2-hydroxy-methylphenylpropane-1-one (1173); and 0.4 parts by weight of additives. The PET substrate layer is 131 μm thick, the adhesive layer is 22 μm thick, and the optical layer is 65 μm thick.

[0144] Table 1 Performance tests of Examples 1-8 and Comparative Examples 1-4

[0145]

[0146] The test results from the above embodiments and comparative examples show that, while maintaining the same or similar thickness, the peel force between the core layer and the PET substrate of the composite film optical brightening film provided by the present invention decreases. This is because the adhesive is not fully cured and has a certain degree of fluidity. Simultaneously, the thermal shrinkage rate and coefficient of thermal expansion are reduced to some extent, thus improving anti-warping performance and resulting in a smaller warping value. The optical brightening films provided in Embodiments 4, 5, and 7 of the present invention have a warping value of <2mm, exhibiting better anti-warping performance and can be applied to backlight modules of different sizes.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent variations and modifications made based on the content of the present invention are covered within the patent scope of the present invention.

Claims

1. The application of an adhesive layer in optical thin films resistant to high-temperature warping deformation. The adhesive layer comprises 20%-30% of the bonding monomer isoborneol acrylate, 35%-45% of acrylic resin oligomer, 16%-20% of bisphenol A diacrylate, 5%-10% of the reactive diluent β-hydroxyethyl methacrylate, 0.5%-1.5% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 5%-8% of ionomer gel. The optical film comprises a substrate layer, an optical layer, and a protective layer. The thickness of the substrate layer is between 50-150 μm, and the thickness of the optical layer is between 50-100 μm. Both the substrate layer and the optical layer are coated with an anti-glare coating liquid. An adhesive layer is provided between the substrate layer and the optical layer, and the thickness of the adhesive layer is between 2-25 μm. The protective layer contains an inorganic material with good thermal conductivity, and the thickness of the protective layer is between 5-20 μm. The optical layer is selected as the core layer; The adhesive layer has a certain degree of resilience. When the core layer deforms due to heat, it can provide a pull-back force, reduce the warpage height, and avoid the film from warping significantly due to temperature. The warpage value of the optical brightening film is <2mm. The application enables the optical film to resist deformation and warping at a high temperature of 50°C while ensuring its excellent optical performance, which includes at least brightness and peel strength.

2. The application according to claim 1, characterized in that, The anti-glare coating liquid includes deca-functional polyurethane acrylic resin oligomer, hexa-functional acrylic monomer, photoinitiator, leveling agent, silica anti-glare particles, polymethyl methacrylate, and organic solvent.

3. The application according to claim 1, characterized in that, The core layer is a reflective polarizing brightening film.

4. The application according to claim 1, characterized in that, The substrate layer is selected as a PET substrate layer, and the particulate material coated on the surface of the PET substrate layer and the optical layer is one or a mixture of PMMA (polymethyl methacrylate), silicone, PA (polyamide) and / or PU (polyester).

5. The application according to claim 4, characterized in that, The adhesive layer is located between the core layer and the PET substrate layer, and the thickness of the adhesive layer is between 5-15 μm.

6. The application according to claim 1, characterized in that, The core layer is covered with a protective film, and the upper surface of the protective film has a mesh-like indentation with micropores distributed in the indentation. The pore size of the micropores ranges from 200 to 500 μm.

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