Optical film, polarizer, and display device

Abstract

The invention discloses an optical film, a polaroid and a display device. The optical film has first tensile strength in the first direction, the optical film has second tensile strength in the second direction, the ratio of the first tensile strength to the second tensile strength is larger than or equal to 0.6 and smaller than or equal to 1.6, and the first direction intersects with the second direction; by balancing the tensile strength of the optical film in different directions, the refractive index difference of the optical film in different directions is smaller, and when the optical film is used in the polaroid and the display device, the rainbow pattern phenomenon of the display device can be effectively improved; furthermore, the mechanical properties of the optical film in different directions can be more balanced, the problems of warping, deformation, inaccurate alignment and the like caused by uneven stress are reduced, and the product yield and reliability are improved.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to an optical film, a polarizer, and a display device. Background Technology

[0002] Display devices typically have multiple optical films, such as the protective film of polarizers; however, these optical films are prone to uniaxial orientation problems, which in turn cause birefringence of the light passing through, resulting in rainbow patterns on the display device. Summary of the Invention

[0003] This application provides an optical film, a polarizer, and a display device that can balance the tensile strength of the optical film in different directions, making the refractive index difference of the optical film in different directions smaller, and improving the rainbow effect of the display device containing the optical film.

[0004] This application provides an optical film having a first tensile strength along a first direction and a second tensile strength along a second direction. The ratio of the first tensile strength to the second tensile strength is greater than or equal to 0.6 and less than or equal to 1.6, and the first direction intersects the second direction.

[0005] In one embodiment of this application, the optical film has a first refractive index along the optical axis and a second refractive index along a direction perpendicular to the optical axis, wherein the absolute value of the difference between the first refractive index and the second refractive index is less than or equal to 0.05.

[0006] In one embodiment of this application, the first refractive index is greater than or equal to 1.4 and less than or equal to 1.75;

[0007] The second refractive index is greater than or equal to 1.4 and less than or equal to 1.75.

[0008] In one embodiment of this application, the thickness of the optical film is greater than or equal to 10 micrometers and less than or equal to 80 micrometers.

[0009] In one embodiment of this application, the optical film includes a substrate layer, which includes a first sublayer, a second sublayer, and a third sublayer stacked together. The second sublayer is located between the first sublayer and the third sublayer, and the thickness of the first sublayer and the thickness of the third sublayer are both less than the thickness of the second sublayer.

[0010] In one embodiment of this application, the substrate layer further includes particles dispersed within the first sublayer and the third sublayer.

[0011] In one embodiment of this application, the material of the particles includes at least one of silicon dioxide, calcium carbonate, barium sulfate, organosilicon, and barium dioxide; And / or, the particle size is greater than or equal to 0.05 micrometers and less than or equal to 50 micrometers.

[0012] In one embodiment of this application, the optical film further includes a primer layer located on the side of the first sublayer away from the second sublayer, and on the side of the third sublayer away from the second sublayer.

[0013] In one embodiment of this application, the material of the primer layer includes at least one of polyurethane, acrylate, and polyester.

[0014] In one embodiment of this application, the material of the substrate layer includes at least one of the following: modified or unmodified polyethylene terephthalate, modified or unmodified polyethylene isophthalate, modified or unmodified polyethylene naphthalate, modified or unmodified polybutylene terephthalate, modified or unmodified polycarbonate, copolymers of polyethylene terephthalate, blends of polyethylene terephthalate, polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-1,4-cyclohexanediol ester, and blends of polyethylene terephthalate and polycarbonate.

[0015] In accordance with the above-mentioned objectives of this application, embodiments of this application also provide a polarizer, the polarizer comprising a polarizing layer and an optical film as described above.

[0016] In one embodiment of this application, the polarizer further includes a compensation layer and an adhesive layer, wherein the compensation layer is disposed on the side of the polarizer away from the optical film, and the adhesive layer is disposed on the side of the compensation layer away from the polarizer. And / or, the polarizer further includes the compensation layer, the bonding layer, and the release film, wherein the compensation layer is disposed on the side of the polarizing layer away from the optical film, the bonding layer is disposed on the side of the compensation layer away from the polarizing layer, and the release film is disposed on the side of the bonding layer away from the compensation layer.

[0017] In one embodiment of this application, the polarization degree of the polarizer is greater than or equal to 99%; And / or, the transmittance of the polarizer is greater than or equal to 40%.

[0018] In accordance with the above-mentioned objectives of this application, embodiments of this application also provide a display device, the display device including a display panel and an optical film as described above, the optical film being disposed on at least one side of the display panel; Alternatively, the display device may include the display panel and the polarizer as described above, wherein the polarizer is disposed on at least one side of the display panel.

[0019] This application provides an optical film, a polarizer, and a display device. By balancing the tensile strength of the optical film in different directions, the refractive index difference of the optical film in different directions is reduced. When the optical film is used in the polarizer and the display device, it can effectively improve the rainbow effect of the display device. Furthermore, this application can make the mechanical properties of the optical film more balanced in different directions, reducing problems such as warping, deformation, and misalignment caused by uneven stress, thereby improving product yield and reliability.

[0020] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0023] Figure 1 A schematic diagram of the structure of an optical film provided in an embodiment of this application; Figure 2 This is a schematic diagram of another structure of the optical film provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of the substrate layer provided in an embodiment of this application; Figure 4 This is a schematic diagram of a polarizer provided in an embodiment of this application; Figure 5 This is a schematic diagram of another structure of the polarizer provided in an embodiment of this application; Figure 6 A schematic diagram of the structure of a display device provided in an embodiment of this application; Figure 7 This is another schematic diagram of the display device provided in the embodiments of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0025] Please refer to Figure 1 This application provides an optical film 10, which has a first tensile strength along a first direction and a second tensile strength along a second direction. The ratio of the first tensile strength to the second tensile strength is greater than or equal to 0.6 and less than or equal to 1.6. The first direction intersects the second direction.

[0026] In the implementation process, the embodiments of this application balance the tensile strength of the optical film 10 in different directions, so that the refractive index difference of the optical film 10 in different directions is smaller. When the optical film 10 is used in polarizers and display devices, it can effectively improve the rainbow effect of the display device. Furthermore, this application can make the mechanical properties of the optical film 10 more balanced in different directions, reduce problems such as warping, deformation and misalignment caused by uneven stress, and improve product yield and reliability.

[0027] In some embodiments, the first direction is perpendicular to the second direction, and both the first direction and the second direction are parallel to the film surface of the optical film 10, that is, both the first direction and the second direction are perpendicular to the thickness direction of the optical film 10.

[0028] It should be noted that, in this embodiment, the first direction can be the direction perpendicular to the mechanical conveying (Transverse Direction, TD), i.e., the lateral stretching direction; while the second direction can be the mechanical conveying direction (Machine Direction, MD), i.e., the longitudinal stretching direction; the lateral stretching direction is the direction perpendicular to the longitudinal stretching direction, which is also the width direction of the optical film 10 (perpendicular to the conveying direction). The longitudinal stretching direction is also the winding direction of the optical film 10. The optical film 10 is typically shipped in a wound state, and the winding direction is the direction in which the optical film 10 is wound forward onto the winding shaft after processing, i.e., the extension direction of the optical film 10. The direction perpendicular to the winding direction is the width direction of the optical film 10.

[0029] Specifically, please continue to refer to Figure 1In this embodiment of the application, the tensile strength of the optical film 10 in different directions can be achieved by controlling the stretching ratio during the stretching process in different directions; that is, the stretching ratio of the optical film 10 in different directions can be controlled to be closer, so that the tensile strength of the optical film 10 in different directions is closer.

[0030] In some embodiments, the ratio of the first tensile strength to the second tensile strength can be 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, or 1.6. Preferably, the ratio of the first tensile strength to the second tensile strength is greater than or equal to 0.8 and less than or equal to 1.2.

[0031] In some embodiments, the stretching ratio of the optical film 10 along the first direction is greater than or equal to 2 and less than or equal to 5, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5; the stretching ratio of the optical film 10 along the second direction is greater than or equal to 2 and less than or equal to 5, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5.

[0032] It is understood that the stretching ratio of the optical film 10 along the first direction is the ratio of the length of the optical film 10 after stretching along the first direction to the initial length. Correspondingly, the stretching ratio of the optical film 10 along the second direction is the ratio of the length of the optical film 10 after stretching along the second direction to the initial length.

[0033] In some embodiments, the tensile strength of the optical film 10 along the first direction is greater than or equal to 180 MPa and less than or equal to 300 MPa; for example, the tensile strength of the optical film 10 along the first direction can be 180 MPa, 190 MPa, 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa or 300 MPa.

[0034] More preferably, the tensile strength of the optical film 10 along the first direction is greater than or equal to 210 MPa and less than or equal to 270 MPa.

[0035] In some embodiments, the tensile strength of the optical film 10 along the second direction is greater than or equal to 180 MPa and less than or equal to 300 MPa; for example, the tensile strength of the optical film 10 along the second direction can be 180 MPa, 190 MPa, 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa or 300 MPa.

[0036] More preferably, the tensile strength of the optical film 10 along the second direction is greater than or equal to 210 MPa and less than or equal to 270 MPa.

[0037] In some embodiments, the material of the optical film 10 includes polyester material; further, the material of the optical film 10 includes at least one of modified or unmodified polyethylene terephthalate, modified or unmodified polyethylene isophthalate, modified or unmodified polyethylene naphthalate, modified or unmodified polybutylene terephthalate, modified or unmodified polycarbonate, copolymers of polyethylene terephthalate, and blends of polyethylene terephthalate.

[0038] For example, the material of the optical film 10 includes at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene terephthalate-ethylene isophthalate copolymer, blends of polyethylene terephthalate and polyethylene terephthalate-ethylene isophthalate copolymer, blends of polyethylene terephthalate and polyethylene terephthalate-1,4-cyclohexanediol ester, and blends of polyethylene terephthalate and polycarbonate.

[0039] In some embodiments, please refer to Figure 1 The optical film 10 may include a substrate layer 11.

[0040] In some embodiments, the material of the substrate layer 11 includes a polyester material; further, the material of the substrate layer 11 includes at least one of the following: modified or unmodified polyethylene terephthalate, modified or unmodified polyethylene isophthalate, modified or unmodified polyethylene naphthalate, modified or unmodified polybutylene terephthalate, modified or unmodified polycarbonate, copolymers of polyethylene terephthalate, blends of polyethylene terephthalate, polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-1,4-cyclohexanediol ester, and blends of polyethylene terephthalate and polycarbonate.

[0041] In some embodiments, the optical film 10 further includes a primer layer 12 located on at least one side of the substrate layer 11.

[0042] It should be noted that the primer layer 12 can be a primer disposed on at least one side of the substrate layer 11; the primer layer 12 can improve the wettability of the surface of the substrate layer 11, so that the coating liquid of the subsequent film layer can be spread evenly to form a defect-free and smooth coating; wherein, one side of the primer layer 12 contains functional groups that can form a good bond with the surface of the substrate layer 11, and the other side of the primer layer 12 contains functional groups that can be compatible with or chemically cross-linked with the resin of other functional coatings, thereby "bridging" the substrate layer 11 and other film layers to firmly lock them together, thereby increasing the adhesion between the substrate layer 11 and other film layers.

[0043] In some embodiments, the material of the primer layer 12 includes at least one of polyurethane, acrylate and polyester.

[0044] like Figure 1 As shown, the primer layer 12 may be located on one side of the substrate layer 11; or, as... Figure 2 As shown, the primer layer 12 can be located on opposite sides of the substrate layer 11.

[0045] It is understood that the optical film 10 has a light-incident side and a light-emitting side during application, and correspondingly, the substrate layer 11 also has a light-incident side and a light-emitting side; while the primer layer 12 can be located on one of the light-incident side and the light-emitting side of the substrate layer 11, or the primer layer 12 can be distributed on both the light-incident side and the light-emitting side of the substrate layer 11 at the same time, so as to improve the adhesion of the film layers on both sides of the substrate layer 11.

[0046] In some embodiments, the optical film 10 further includes particles 13, and the particles 13 may be distributed in at least one of the substrate layer 11 and the primer layer 12; and as Figure 1 and Figure 2 As shown, taking the distribution of particles 13 in the substrate layer 11 as an example; and in this embodiment of the application, the addition of particles 13 to the optical film 10 can increase the scattering effect of light, thereby improving the glare phenomenon. When the optical film 10 is used in the display device, the rainbow effect of the display device can be improved.

[0047] In some embodiments, the substrate layer 11 may include one or more sublayers stacked together, and the particles 13 are distributed in at least one of the one or more sublayers; that is, the particles 13 may be distributed in at least one of the one or more sublayers and the primer layer 12.

[0048] In some embodiments, please refer to Figure 3 The substrate layer 11 includes a first sublayer 111, a second sublayer 112, and a third sublayer 113 stacked together. The second sublayer 112 is located between the first sublayer 111 and the third sublayer 113, and the thickness of the first sublayer 111 and the thickness of the third sublayer 113 are both less than the thickness of the second sublayer 112.

[0049] Furthermore, the particles 13 are distributed in the first sub-layer 111 and the third sub-layer 113; for example, when the substrate layer 11 is formed by a three-layer co-extrusion process, the substrate layer 11 consists of three sub-layers stacked together, and the particles are distributed in the outer layer of the substrate layer 11; wherein, the outer layer of the substrate layer 11 is the first sub-layer 111 and the third sub-layer 113, and the second sub-layer 112 is the core layer of the substrate layer 11; wherein, when the particles 13 are distributed in the first sub-layer 111 and the third sub-layer 113, that is, located in the outer layer of the substrate layer 11, the probability of adhesion of the substrate layer 11 during film winding in the process can be reduced.

[0050] In some embodiments, when the optical film 10 further includes a primer layer 12, the primer layer 12 is located on the side of the first sub-layer 111 away from the second sub-layer 112, and on the side of the third sub-layer 113 away from the second sub-layer 112.

[0051] In some embodiments, the material of the particle 13 includes at least one of silicon dioxide, calcium carbonate, barium sulfate, organosilicon, and barium dioxide.

[0052] In some embodiments, the particle 13 has a particle size greater than or equal to 0.05 micrometers and less than or equal to 50 micrometers; for example, it can be 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm.

[0053] It should be noted that, in this embodiment, the tensile strength of the optical film 10 in different directions can be achieved by controlling the stretching ratio during the stretching process in different directions. The adjustment of the stretching ratio of the optical film 10 in different directions will also affect the refractive index of the optical film 10 in different directions. For example, in this embodiment, the stretching ratio of the optical film 10 in different directions is made similar, which can make the tensile strength of the optical film 10 in different directions similar, and also make the refractive index of the optical film 10 in different directions similar, which can effectively suppress the rainbow effect of the display device.

[0054] In some embodiments, the optical film 10 has a first refractive index along the optical axis and a second refractive index along a direction perpendicular to the optical axis. The absolute value of the difference between the first refractive index and the second refractive index is less than or equal to 0.05, for example, it can be 0.05, 0.04, 0.03, 0.02, 0.01 or 0.

[0055] In one embodiment of this application, the first refractive index is greater than or equal to 1.4 and less than or equal to 1.75, for example, it can be 1.4, 1.45, 1.46, 1.47, 1.48, 1.49, 1.5, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.6, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.7, 1.71, 1.72, 1.73, 1.74 or 1.75.

[0056] The second refractive index is greater than or equal to 1.4 and less than or equal to 1.75, for example, it can be 1.4, 1.45, 1.46, 1.47, 1.48, 1.49, 1.5, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.6, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.7, 1.71, 1.72, 1.73, 1.74 or 1.75.

[0057] It should be noted that the refractive index of the optical film 10 described in this embodiment can be determined using an Abbe refractometer manufactured by Atago Co., Ltd., Japan. M1 is used for testing; and the optical axis of the optical film 10 is the direction with the largest in-plane retardation value.

[0058] In some embodiments, the thickness of the optical film 10 is greater than or equal to 10 micrometers and less than or equal to 80 micrometers, for example, it can be 10 micrometers, 20 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers or 80 micrometers.

[0059] Furthermore, in some embodiments, the stretching temperature range of the optical film 10 along the first direction during the stretching process can be 110℃-150℃, and preferably 120-130℃; the stretching temperature range of the optical film 10 along the second direction during the stretching process can be 60℃-90℃, and preferably 70℃-80℃; this can be more conducive to a more balanced orientation of the optical film 10 during the stretching process in the first and second directions.

[0060] Continuing from the above, this application embodiment balances the tensile strength of the optical film 10 in different directions, making the refractive index difference of the optical film 10 in different directions smaller. When the optical film 10 is used in polarizers and display devices, it can effectively improve the rainbow effect of the display device. Furthermore, this application can make the mechanical properties of the optical film 10 more balanced in different directions, reducing problems such as warping, deformation and misalignment caused by uneven stress, and improving product yield and reliability.

[0061] In addition, this application embodiment also provides a method for manufacturing an optical film, the method comprising the following steps: An optical film material is stretched along a first direction and a second direction to form the optical film 10, wherein the first direction and the second direction intersect; wherein the optical film 10 has a first tensile strength along the first direction and a second tensile strength along the second direction, and the ratio of the first tensile strength to the second tensile strength is greater than or equal to 0.6 and less than or equal to 1.6.

[0062] It is understood that when the optical film 10 is prepared according to the embodiments of this application, the optical film material is stretched in different directions, thereby making the resulting optical film 10 biaxially oriented. This can reduce the difference in tensile strength of the optical film 10 in different directions, making the difference in refractive index of the optical film 10 in different directions smaller. When the optical film 10 is used in polarizers and display devices, it can effectively improve the rainbow effect of the display device. Furthermore, this application can make the mechanical properties of the optical film 10 more balanced in different directions, reducing problems such as warping, deformation and misalignment caused by uneven stress, and improving product yield and reliability.

[0063] In some embodiments, the first direction is perpendicular to the second direction.

[0064] It should be noted that, in this embodiment, the first direction can be the direction perpendicular to the mechanical conveying (Transverse Direction, TD), i.e., the lateral stretching direction; while the second direction can be the mechanical conveying direction (Machine Direction, MD), i.e., the longitudinal stretching direction; the lateral stretching direction is the direction perpendicular to the longitudinal stretching direction, which is also the width direction of the optical film 10 (perpendicular to the conveying direction). The longitudinal stretching direction is also the winding direction of the optical film 10. The optical film 10 is typically shipped in a wound state, and the winding direction is the direction in which the optical film 10 is wound forward onto the winding shaft after processing, i.e., the extension direction of the optical film 10. The direction perpendicular to the winding direction is the width direction of the optical film 10.

[0065] In one specific embodiment, the step of stretching the optical film material along a first direction and a second direction to form the optical film 10 includes: extruding and molding the material of the optical film 10 to obtain the optical film material; placing the optical film material in a stretching device, which can first stretch it along the forward direction of the production line, i.e., stretching it along the MD direction (second direction); then, feeding the optical film material stretched along the MD direction into a tenter frame, which has movable clamps or fixtures on both sides. In a hot air heated oven, the clamps unfold along the track to both sides, stretching the optical film material in the TD direction (first direction), thereby allowing the optical film material to be stretched along the first direction and the second direction respectively.

[0066] In some embodiments, this application also provides a method for testing the tensile strength of an optical film 10, the method comprising: First, on the optical film 10, a first group of samples is cut along the direction parallel to MD (second direction), and a second group of samples is cut along the direction parallel to TD (first direction); and each group of samples has no less than 5 samples.

[0067] Next, a micrometer or thickness gauge with an accuracy of ≥0.001mm can be used to measure the thickness at least 3 points on the parallel section of the sample, and the width can be accurately measured using calipers; and the average cross-sectional area of ​​the sample can be calculated.

[0068] Then, a universal electronic tensile testing machine can be used to symmetrically clamp the specimens in the upper and lower clamps of the universal material testing machine. Ensure that: the length direction of the first set of specimens is consistent with the tensile force direction, and the tensile force direction is the MD direction of the optical film 10; the length direction of the second set of specimens is consistent with the tensile force direction, and the tensile force direction is the TD direction of the optical film 10.

[0069] Furthermore, the universal electronic tensile testing machine is started, and the sample is continuously stretched until it breaks; the equipment automatically records the tensile-displacement curve.

[0070] Finally, the tensile strength is calculated based on the force-displacement curve and the tensile strength formula, which is σ=Fmax / A; where: σ is the tensile strength (MPa), Fmax is the maximum tensile force (N), and A is the initial average cross-sectional area of ​​the specimen (m²).

[0071] In some embodiments, the stretching ratio of the optical film 10 along the first direction is greater than or equal to 2 and less than or equal to 5, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5; the stretching ratio of the optical film 10 along the second direction is greater than or equal to 2 and less than or equal to 5, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5.

[0072] It is understood that the stretching ratio of the optical film 10 along the first direction is the ratio of the length of the optical film 10 after stretching along the first direction to the initial length. Correspondingly, the stretching ratio of the optical film 10 along the second direction is the ratio of the length of the optical film 10 after stretching along the second direction to the initial length.

[0073] Additionally, please refer to Figure 4 This application embodiment also provides a polarizer 20, which includes a polarizing layer 21 and an optical film 10, and the optical film 10 can be the optical film 10 described in the above embodiment.

[0074] In some embodiments, the polarizer 20 further includes a compensation layer 22 and an adhesive layer 23. The compensation layer 22 is disposed on the side of the polarizer 21 away from the optical film 10, and the adhesive layer 23 is disposed on the side of the compensation layer 22 away from the polarizer 21. It should be noted that the adhesive layer 23 is a film layer used to bond the polarizer 20 to the display panel, that is, the adhesive layer 23 is located between the polarizer 21 and the display panel.

[0075] In some embodiments, the polarizer 20 further includes the compensation layer 22, the bonding layer 23, and the release film 24. The compensation layer 22 is disposed on the side of the polarizer 21 away from the optical film 10, the bonding layer 23 is disposed on the side of the compensation layer 22 away from the polarizer 21, and the release film 24 is disposed on the side of the bonding layer 23 away from the compensation layer 22. The release film 24 needs to be removed when the polarizer 20 is bonded, and then bonded to the display panel through the bonding layer 23.

[0076] In some embodiments, the polarizer 20 further includes a protective film 25 disposed on the side of the optical film 10 away from the polarizing layer 21, and the protective film 25 is used to protect the polarizer 20, and the protective film 25 can be removed when the polarizer 20 is attached.

[0077] In some embodiments, the polarizing layer 21 may be a polyvinyl alcohol film stretched and dyed with dichroic dyes, wherein the dichroic dyes may be inorganic materials, such as iodine / potassium iodide (I2 / KI), or organic materials, such as anthraquinone dyes, azo dyes and triphenyldiazepine and derivative dyes, monomethanone and polymethanone dyes, heterocyclic dyes, etc., or mixtures thereof, but are not limited thereto.

[0078] In some embodiments, the thickness of the polarizing layer 21 can be greater than or equal to 2 micrometers and less than or equal to 50 micrometers, for example, it can be 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers or 50 micrometers.

[0079] In some embodiments, the material of the compensation layer 22 may include, but is not limited to, cellulose triacetyl (TAC), polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polycyclic olefin (COP / Cyclo Olefin Copolymer (COC), and polyethylene naphthalate (PEN).

[0080] In some embodiments, the thickness of the compensation layer 22 may be greater than or equal to 2 micrometers and less than or equal to 80 micrometers, for example, it may be 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 75 micrometers or 80 micrometers.

[0081] In some embodiments, the material of the bonding layer 23 may include a pressure-sensitive adhesive (PSA) layer selected from acrylate copolymers.

[0082] In some embodiments, the thickness of the bonding layer 23 may be greater than or equal to 5 micrometers and less than or equal to 30 micrometers, for example, it may be 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers or 30 micrometers.

[0083] In some embodiments, the release film 24 may be obtained by coating a release agent onto the surface of the bonding layer 23 with polyethylene terephthalate; and the thickness of the release film 24 may be greater than or equal to 20 micrometers and less than or equal to 100 micrometers, for example, it may be 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 75 micrometers, 80 micrometers, 85 micrometers, 90 micrometers, 95 micrometers or 100 micrometers.

[0084] It should be noted that the polarizer 20 may also include multiple adhesive layers for bonding different film layers in the polarizer 20 together.

[0085] In some embodiments, the polarizer 20 includes a first adhesive layer 26 and a second adhesive layer 27; the first adhesive layer 26 is disposed between the optical film 10 and the polarizing layer 21, and the first adhesive layer 26 is used to bond the optical film 10 and the polarizing layer 21 together; the second adhesive layer 27 is disposed between the polarizing layer 21 and the compensation layer 22, and the second adhesive layer 27 is used to bond the polarizing layer 21 and the compensation layer 22 together.

[0086] In some embodiments, the materials of the first adhesive layer 26 and the second adhesive layer 27 are each independently selected from at least one of water-based adhesives, pressure-sensitive adhesives, and radiation-curing adhesives; wherein, the material of the water-based adhesive may be selected from polyvinyl alcohol, the material of the pressure-sensitive adhesive may be selected from acrylate copolymers, and the material of the radiation-curing adhesive may be selected from polyfunctional acrylate monomers.

[0087] In some embodiments, the thickness of the first adhesive layer 26 may be greater than or equal to 2 micrometers and less than or equal to 30 micrometers, for example, it may be 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers or 30 micrometers.

[0088] In some embodiments, the thickness of the second adhesive layer 27 may be greater than or equal to 2 micrometers and less than or equal to 30 micrometers, for example, it may be 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers or 30 micrometers.

[0089] In some embodiments, please refer to Figure 4 The polarizer 20 can be a first type polarizer 210, and the first type polarizer 210 further includes a functional coating 28 disposed between the protective film 25 and the optical film 10, and the functional coating 28 can be selected from at least one of a hardening layer, an anti-reflection layer, an anti-glare layer, an anti-fingerprint layer, an anti-fouling layer, and an antistatic layer.

[0090] In some embodiments, the thickness of the functional coating 28 may be greater than or equal to 2 micrometers and less than or equal to 30 micrometers, for example, it may be 2 micrometers, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers or 30 micrometers.

[0091] It should be noted that the first type of polarizer 210 can be used as an upper polarizer in a liquid crystal display, and the functional coating 28 in the first type of polarizer 210 can be located on the side of the optical film 10 away from the liquid crystal display panel in the liquid crystal display.

[0092] In some embodiments, please refer to Figure 5The polarizer 20 can be a second type of polarizer 220, and the second type of polarizer 220 does not have the functional coating 28. The protective film 25 can be disposed on the side of the optical film 10 away from the polarizing layer 21.

[0093] It should be noted that the second type of polarizer 220 can be used as the lower polarizer in the liquid crystal display.

[0094] In addition, the first type of polarizer 210 and the second type of polarizer 220 can also be used in organic light-emitting diode displays.

[0095] In some embodiments, the polarization degree of the polarizer is greater than or equal to 99%.

[0096] In some embodiments, the transmittance of the polarizer is greater than or equal to 40%, for example, it can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%.

[0097] Continuing on the above, this application also provides Comparative Examples 1 and 2, as well as Examples 1 to 7, to verify the polarizer 20 provided in this application.

[0098] In Comparative Examples 1 and 2, and Examples 1 to 7, a first type of polarizer 210 and a second type of polarizer 220 were provided. In the first type of polarizer 210 and the second type of polarizer 220, the polarizing layer 21 was formed by stretching and impregnating a polyvinyl alcohol film with iodine / potassium iodide (I2 / KI), with a thickness of 20 micrometers. The compensation layer 22 was made of cellulose triacetate, with a thickness of 40 micrometers. The bonding layer 23 was made of acrylate copolymer, with a thickness of 20 micrometers. The first adhesive layer 26 and the second adhesive layer 27 were both made of polyvinyl alcohol, with a thickness of 1 micrometer.

[0099] Furthermore, in the first type of polarizer 210, the functional coating 28 is an anti-glare layer, and the material of the functional coating 28 is silicon dioxide with a thickness of 3 micrometers.

[0100] In Comparative Examples 1 and 2, and Examples 1 to 5, the material of the optical film 10 in the first type of polarizer 210 and the second type of polarizer 220 is polyethylene terephthalate.

[0101] In Example 6, the optical film 10 is made of polyethylene terephthalate and polyethylene (ethylene terephthalate-ethylene isophthalate) copolymer, and the mass ratio of polyethylene terephthalate to polyethylene (ethylene terephthalate-ethylene isophthalate) copolymer is 8:2.

[0102] In Example 7, the optical film 10 is made of polyethylene terephthalate and polyethylene terephthalate-1,4-cyclohexanediethanol ester, and the mass ratio of polyethylene terephthalate to polyethylene terephthalate-1,4-cyclohexanediethanol ester is 9:1.

[0103] In Comparative Examples 1 and 2, and Examples 1 to 7, the first type of polarizer 210 and the second type of polarizer 220 were respectively attached to both sides of the liquid crystal panel, with the first type of polarizer 210 located on the light-emitting side of the liquid crystal panel and the second type of polarizer 220 located on the light-incident side of the liquid crystal panel; then, a backlight was connected and the panel was illuminated; then, the degree of rainbow pattern was recorded from the front and from a large angle of oblique view, and the viewing angle could be from 0° to 80°.

[0104] In Comparative Examples 1 and 2, and Examples 1 to 7, the thickness and optical parameters of the optical film 10 can be found in Table 1 below.

[0105] Table 1

[0106] As can be seen from Table 1, the first tensile strength and the second tensile strength are closest in Examples 1, 6 and 7, and therefore no rainbow effect is produced when the polarizer 20 in Examples 1, 6 and 7 is tested. In Examples 2 to 5, the ratio of the first tensile strength and the second tensile strength is between 0.6 and 1.6, and only a slight rainbow effect is produced when the polarizer 20 in Examples 2 to 5 is tested. However, the ratio of the first tensile strength and the second tensile strength in Comparative Examples 1 and 2 is above 1.6, which is a large difference and will produce obvious rainbow effect.

[0107] In summary, by reducing the difference in tensile strength of the optical film 10 in different directions, the refractive index difference of the optical film 10 in different directions is smaller. When the optical film 10 is used in polarizers and display devices, it can effectively improve the rainbow effect of the display device. Furthermore, this application can make the mechanical properties of the optical film 10 more balanced in different directions, which is beneficial to the subsequent manufacturing process of the polarizer 20. Moreover, the optical film 10 can reduce problems such as warping, deformation and misalignment caused by uneven stress, which is beneficial to the application of the optical film 10 in flexible displays and improves product yield and reliability.

[0108] Please refer to Figure 1 , Figure 6 and Figure 7This application embodiment also provides a display device, the display device including a display panel 31 and an optical film 10 as described above, the optical film 10 being disposed on at least one side of the display panel 31; Alternatively, the display device may include a display panel 31 and a polarizer 20 as described above, wherein the polarizer 20 is disposed on at least one side of the display panel 31.

[0109] In one specific implementation, please refer to Figure 6 If the display device is a liquid crystal display, then the display device includes a display panel 31, a first type polarizer 210 disposed on the light-emitting side of the display panel 31, a second type polarizer 220 disposed on the side of the display panel 31 away from the first type polarizer 210, and a backlight module 32 disposed on the side of the second type polarizer 220 away from the first type polarizer 210.

[0110] Both the first type of polarizer 210 and the second type of polarizer 220 can be linear polarizers; and the light transmission axis direction of the first type of polarizer 210 is perpendicular to the light transmission axis direction of the second type of polarizer 220.

[0111] In some embodiments, the display panel 31 may include an array substrate and a counter substrate disposed opposite each other, and a liquid crystal layer located between the array substrate and the counter substrate.

[0112] The array substrate includes thin-film transistors, scan lines, data lines, pixel electrodes, common electrodes, etc., while the color filter substrate includes a black matrix (BM), RGB color resist layers, etc. The liquid crystal display panel also includes various other display components, such as alignment films and frame adhesives between the array substrate and the color filter substrate. These details can be implemented with reference to existing technologies and will not be elaborated here.

[0113] Furthermore, the array substrate includes an array of thin-film transistors (TFTs), each TFT comprising a semiconductor device, a gate metal, a source metal, and a drain metal. The array substrate also includes horizontally arranged scan lines and vertically arranged data lines. The scan lines and data lines intersect perpendicularly to form a plurality of display pixels. Each display pixel contains a pixel electrode and at least one TFT. The gate metal of one TFT is connected to a corresponding scan line, the source metal of one TFT is connected to a corresponding data line, and the drain metal of one TFT is connected to a corresponding pixel electrode. The scan lines provide switching control signals to the connected TFTs, and the data lines provide data signals to the connected TFTs. When a TFT is in the on state, the data signal on the data line passes through the source and drain of the TFT and is transmitted to the corresponding pixel electrode, thereby adjusting the voltage difference between the pixel electrode and the common electrode.

[0114] The common electrode plate has a fixed voltage value, and a voltage difference is formed between the common electrode plate and the pixel electrode to drive the liquid crystal molecules of the liquid crystal layer to deflect according to the pretilt angle, thereby controlling the amount of light transmitted and thus realizing the display of the image.

[0115] The backlight module 32 provides backlight for the display panel 31.

[0116] In another specific implementation, please refer to Figure 7 The display device can be an organic light-emitting diode display, and the display device includes a display panel 31 and a polarizer 20 disposed on the light-emitting side of the display panel 31.

[0117] In some embodiments, the polarizer 20 is a circular polarizer.

[0118] In some embodiments, the display panel 31 includes an array substrate, the array substrate including a substrate and a thin-film transistor layer disposed on the substrate.

[0119] In some embodiments, the substrate can be a rigid substrate, such as a glass substrate; or, the substrate can be a flexible substrate, such as a substrate formed of polyimide. When the substrate is a flexible substrate, the substrate can be formed of multiple sub-substrates of the same material, such as polyimide, and adjacent sub-substrates are bonded together by adhesive sub-layers.

[0120] In some embodiments, the thin-film transistor layer includes a thin-film transistor, which includes a semiconductor located on a substrate. The semiconductor may be formed of polycrystalline silicon or a metal oxide (such as indium gallium zinc oxide). The semiconductor is divided into a channel region and source and drain regions formed on either side of the channel region. The thin-film transistor layer also includes a first gate insulating layer covering the semiconductor. The thin-film transistor also includes a first gate formed on the first gate insulating layer, overlapping the channel region. The first gate may be formed as multiple layers or a single layer comprising a low-resistance material such as Al, Ti, Mo, Cu, Ni, or alloys thereof, or a material with high corrosion resistance. The thin-film transistor layer also includes a second gate insulating layer covering the first gate. The thin-film transistor also includes a second gate located on the second gate insulating layer, overlapping the first gate. The second gate may be formed as multiple layers or a single layer comprising a low-resistance material such as Al, Ti, Mo, Cu, Ni, or alloys thereof, or a material with high corrosion resistance. The thin-film transistor layer also includes a first interlayer insulating layer formed on the second gate. The first interlayer insulating layer, the first gate insulating layer, and the second gate insulating layer include source contact holes and drain contact holes, and the source region and the drain region are exposed through the source contact holes and drain contact holes, respectively.

[0121] The thin-film transistor also includes a source and a drain disposed on the same layer. Both the source and drain are formed on the first interlayer insulating layer. The source is connected to the source region through a source contact hole, and the drain is connected to the drain region through a drain contact hole. The source and drain can be multiple layers or a single layer formed of low-resistance materials such as Al, Ti, Mo, Cu, Ni, or their alloys, or materials with high corrosion resistance. For example, the source and drain can be a triple layer of Ti / Cu / Ti, Ti / Ag / Ti, Ti / Al / Ti, or Mo / Al / Mo, or other single-layer or multi-layer structures.

[0122] In some embodiments, the thin-film transistor layer further includes at least one planarization layer located on the side of the first interlayer insulating layer away from the substrate, the at least one planarization layer covering the source and drain.

[0123] In some embodiments, the display panel further includes a plurality of light-emitting devices disposed on the planarization layer, a pixel definition layer disposed between adjacent light-emitting devices, an encapsulation layer disposed on the light-emitting devices, a touch layer disposed on the encapsulation layer, and other functional layers.

[0124] The polarizer 20 can be disposed on the side of the touch layer away from the encapsulation layer.

[0125] In some embodiments, the display device includes a computer, television, mobile phone, tablet, virtual reality display device, wearable device, etc.

[0126] It is understood that the display device provided in this application embodiment has the polarizer 20 described in the above embodiment, which can effectively improve the rainbow effect of the display device.

[0127] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0128] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0129] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0130] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. An optical film, characterized in that, The optical film has a first tensile strength along a first direction and a second tensile strength along a second direction. The ratio of the first tensile strength to the second tensile strength is greater than or equal to 0.6 and less than or equal to 1.

6. The first direction intersects the second direction.

2. The optical film according to claim 1, characterized in that, The optical film has a first refractive index along the optical axis and a second refractive index along a direction perpendicular to the optical axis. The absolute value of the difference between the first refractive index and the second refractive index is less than or equal to 0.

05.

3. The optical film according to claim 2, characterized in that, The first refractive index is greater than or equal to 1.4 and less than or equal to 1.75; The second refractive index is greater than or equal to 1.4 and less than or equal to 1.

75.

4. The optical film according to claim 1, characterized in that, The thickness of the optical film is greater than or equal to 10 micrometers and less than or equal to 80 micrometers.

5. The optical film according to any one of claims 1 to 4, characterized in that, The optical film includes a substrate layer, which includes a first sublayer, a second sublayer, and a third sublayer stacked together. The second sublayer is located between the first sublayer and the third sublayer. The thickness of the first sublayer and the thickness of the third sublayer are both less than the thickness of the second sublayer.

6. The optical film according to claim 5, characterized in that, The substrate layer also includes particles dispersed within the first sublayer and the third sublayer.

7. The optical film according to claim 6, characterized in that, The material of the particles includes at least one of silicon dioxide, calcium carbonate, barium sulfate, organosilicon, and barium dioxide; And / or, the particle size is greater than or equal to 0.05 micrometers and less than or equal to 50 micrometers.

8. The optical film according to claim 5, characterized in that, The optical film further includes a primer layer located on the side of the first sublayer away from the second sublayer, and on the side of the third sublayer away from the second sublayer.

9. The optical film according to claim 8, characterized in that, The material of the primer layer includes at least one of polyurethane, acrylate and polyester.

10. The optical film according to claim 5, characterized in that, The material of the substrate layer includes at least one of the following: modified or unmodified polyethylene terephthalate, modified or unmodified polyethylene isophthalate, modified or unmodified polyethylene naphthalate, modified or unmodified polybutylene terephthalate, modified or unmodified polycarbonate, copolymers of polyethylene terephthalate, blends of polyethylene terephthalate, polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-ethylene isophthalate copolymers, blends of polyethylene terephthalate and polyethylene terephthalate-1,4-cyclohexanediol ester, and blends of polyethylene terephthalate and polycarbonate.

11. A polarizer, characterized in that, The polarizer includes a polarizing layer and an optical film as described in any one of claims 1 to 10.

12. The polarizer according to claim 11, characterized in that, The polarizer further includes a compensation layer and an adhesive layer. The compensation layer is disposed on the side of the polarizer away from the optical film, and the adhesive layer is disposed on the side of the compensation layer away from the polarizer. And / or, the polarizer further includes the compensation layer, the bonding layer, and the release film, wherein the compensation layer is disposed on the side of the polarizing layer away from the optical film, the bonding layer is disposed on the side of the compensation layer away from the polarizing layer, and the release film is disposed on the side of the bonding layer away from the compensation layer.

13. The polarizer according to claim 11, characterized in that, The polarization degree of the polarizer is greater than or equal to 99%; And / or, the transmittance of the polarizer is greater than or equal to 40%.

14. A display device, characterized in that, The display device includes a display panel and an optical film as described in any one of claims 1 to 10, wherein the optical film is disposed on at least one side of the display panel; Alternatively, the display device may include the display panel and a polarizer as described in any one of claims 11 to 13, the polarizer being disposed on at least one side of the display panel.

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