Optical film, polarizing plate, and display device

Abstract

The application discloses an optical film, a polarizer and a display device. The optical film comprises a plurality of regions. The slow axis angle of at least one region ranges from 5° to 55°. The slow axis angle is the angle between the slow axis of the optical film and the transverse stretching direction of the optical film. The transverse stretching direction is perpendicular to the winding direction of the optical film. The optical film with a high slow axis angle can be roll-to-roll attached with the polarization layer in the polarizer or other optical film layers, and good polarization elimination function is achieved.

Description

Technical Field

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

[0002] Liquid crystal displays (LCDs) emit light with a fixed polarization direction. Prolonged use can cause eye damage, such as myopia. This is mainly because when linearly polarized light enters the eye, some lutein is active, while when circularly polarized light enters the eye, all lutein is active, effectively reducing blue light entering the retina and thus reducing eye damage. Therefore, optical films with anti-polarization effects are usually designed on the surface of LCDs to improve the above defects.

[0003] Currently, commonly used optical films with depolarization effects include quarter-wave plates and high-retardation films. However, quarter-wave plates have complex manufacturing processes and are extremely expensive, and are currently only used in some high-end products. Although high-retardation films are less expensive, their slow axis angle is close to 0 degrees. High-retardation films need to form an angle of about 45 degrees with the absorption or transmission axis of the polarizing film on the light-emitting side to achieve a good depolarization effect. Therefore, the high-retardation film needs to be cut first, then pasted onto the receiving film at an angle, and then laminated with the polarizing film. As a result, roll-to-roll lamination is not possible, which affects production efficiency and yield, and makes it difficult to achieve large-size applications. Summary of the Invention

[0004] This application provides an optical film, a polarizer, and a display device. The optical film of this application has a high slow axis angle, can be rolled up and bonded with the polarizing layer or other optical film layers in the polarizer, and achieves good depolarization function.

[0005] This application provides an optical film comprising multiple regions, wherein the slow axis angle of at least one of the regions is in the range of 5° to 55°, and the slow axis angle is the angle between the slow axis of the optical film and the transverse stretching direction of the optical film.

[0006] In some embodiments, the area of ​​the region with a slow axis angle range of 5° to 55° accounts for 10% to 100% of the total area of ​​the optical film.

[0007] In some embodiments, the optical film includes a first region, a second region, and a third region, wherein the first region and the third region are located on opposite sides of the second region in the transverse stretching direction, and the slow axis angle of the first region is greater than or equal to the slow axis angle of the second region, and the slow axis angle of the third region is greater than or equal to the slow axis angle of the second region.

[0008] The slow axis angle of the first region ranges from 5° to 55°, the slow axis angle of the second region ranges from 0° to 55°, and the slow axis angle of the third region ranges from 5° to 55°.

[0009] In some embodiments, the slow axis angle of at least one of the first region and the third region ranges from 35° to 55°.

[0010] In some embodiments, the slow axis angle of the plurality of regions is in the range of 35° to 55°.

[0011] In some embodiments, the lateral stretching ratio λ of the optical film TD With longitudinal stretch ratio λ MD The relation satisfies: λ TD / λ MD <3.

[0012] In some embodiments, the in-plane retardation value of the optical film is <3000 nm.

[0013] In some embodiments, the refractive index n along the slow axis of the optical film x Refractive index n along the fast axis y The relation satisfies: n x -n y <0.06.

[0014] In some embodiments, the optical film further includes:

[0015] A functional layer, comprising a substrate and particles dispersed in the substrate; and

[0016] An adhesive layer is disposed on at least one side of the functional layer.

[0017] In some embodiments, the functional layer includes a first sublayer, a second sublayer, and a third sublayer disposed sequentially along the thickness direction of the optical film. The first sublayer, the second sublayer, and the third sublayer all contain the substrate, and at least one of the first sublayer, the second sublayer, and the third sublayer contains the particles.

[0018] In some embodiments, the first sublayer contains the particles, and the third sublayer contains the particles.

[0019] In some embodiments, the particle is a birefringent particle, and the ordinary refractive index n of the birefringent particle is... o With unusual light refractive index n e The relation satisfies: n o -n e <0.2.

[0020] In some embodiments, the material of the substrate 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;

[0021] And / or, the material of the particles includes at least one of silicon dioxide, titanium dioxide, calcium carbonate, and organosilicon.

[0022] In some embodiments, the thickness of the optical film ranges from 10 μm to 60 μm.

[0023] This application also provides a polarizer, the polarizer comprising:

[0024] Polarizing layer;

[0025] An optical film is disposed on one side of the polarization layer;

[0026] The optical film used is the optical film described above.

[0027] In some embodiments, the slow axis angle of each region of the optical film ranges from 35° to 55°;

[0028] And / or, the angle between the slow axis of the optical film and the transmission axis of the polarizing layer is in the range of 35° to 55°.

[0029] In some embodiments, the maximum brightness L of the polarizer max and minimum brightness L min The ratio L max / L min The range is from 1 to 20.

[0030] In some embodiments, the polarizer further includes:

[0031] A functional coating is disposed on the side of the optical film away from the polarization layer;

[0032] The functional coating includes at least one of the following: anti-glare coating, hardening coating, anti-reflective coating, anti-fingerprint coating, and antistatic coating.

[0033] In some embodiments, the haze of the functional coating ranges from 1% to 50%.

[0034] This application also provides a display device, the display device comprising:

[0035] Display panel;

[0036] The first polarizer is disposed on the light-emitting side of the display panel.

[0037] The first polarizer is the polarizer described above.

[0038] This application provides an optical film, a polarizer, and a display device. The optical film of this application includes multiple regions, and the slow axis angle of at least one region ranges from 5° to 55°. The slow axis angle is the angle between the slow axis of the optical film and its lateral stretching direction, which is perpendicular to the winding direction of the optical film. This application uses an optical film with a high slow axis angle, which can be rolled-to-roll bonded with the polarizing layer or other optical film layers in a polarizer, achieving excellent depolarization function. Attached Figure Description

[0039] 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 accompanying 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.

[0040] Figure 1 This is a schematic diagram of the winding state of another optical film provided in an embodiment of this application;

[0041] Figure 2 This is a schematic diagram of the structure of an optical film provided in an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of another optical film structure provided in an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the structure of another optical film provided in the embodiments of this application;

[0044] Figure 5 This is a schematic diagram of the structure of a functional layer of an optical film provided in an embodiment of this application;

[0045] Figure 6 This is a schematic diagram of the structure of a polarizer provided in an embodiment of this application;

[0046] Figure 7 This is a schematic diagram of the structure of a display device provided in an embodiment of this application;

[0047] Figure 8 This is a slow axis angle curve of the optical film of Embodiment 1 provided in this application in the wide direction;

[0048] Figure 9 This is a slow axis angle curve of the optical film in the wide direction of Embodiment 2 provided in this application;

[0049] Figure 10 This is a slow axis angle curve of the optical film in the wide direction of Embodiment 3 provided in this application;

[0050] Figure 11 This is a slow axis angle curve of the optical film in the wide direction, which is a comparative example provided in the embodiments of this application.

[0051] Explanation of reference numerals in the attached figures:

[0052] 10. Display device; 100. Optical film; 110. Functional layer; 1101. First sublayer; 1102. Second sublayer; 1103. Third sublayer; 111. Substrate; 112. Particle; 120. Adhesive layer; 200. Polarizer; 201. First polarizer; 202. Second polarizer; 210. Polarizing layer; 211. First polarizing layer; 212. Second polarizing layer; 220. Compensation layer; 221. First compensation layer; 222. Second compensation layer; 230. Functional coating; 300. Display panel; A1. First region; A2. Second region; A3. Third region; L1. First edge; L2. Second edge. Detailed Implementation

[0053] 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 some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] This application provides an optical film 100, please refer to... Figure 1 The optical film 100 of this application includes multiple regions, and the slow axis angle (θ) of at least one region is in the range of 5° to 55°. The aforementioned slow axis angle refers to the angle between the slow axis (B) of the optical film 100 and the transverse (TD) stretching direction of the optical film 100. The transverse stretching direction is perpendicular to the winding direction of the optical film 100.

[0055] The slow-axis angle of at least one region ranges from 5° to 55°. This at least one region can be any region of the optical film 100; for example, it can be a region with an area of ​​5cm x 5cm, but is not limited to this. It is understood that the slow-axis angle of this region can be any angle between 5° and 55°, such as 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, etc.; or, the slow-axis angle of this region can fluctuate between 5° and 55°, for example, the slow-axis angle may differ at different locations within the region, but the slow-axis angle at all locations is within the range of 5° to 55°. It should be noted that the optical film 100 may also include other regions, and the slow-axis angle of these other regions can range from 0° to 55°, but is not limited to this.

[0056] Please refer to Figure 1 The slow axis (B) of the optical film 100 is relative to the fast axis. The slow axis refers to the vibration direction with the highest refractive index in the optical film 100, while the fast axis refers to the vibration direction with the lowest refractive index in the optical film 100. The transverse stretching direction (TD) of the optical film 100 is relative to the longitudinal stretching direction. The longitudinal stretching direction is also the machine direction (MD) during the production of the optical film 100. The transverse stretching direction is perpendicular to the longitudinal stretching direction, and it is also the width direction of the optical film 100 (perpendicular to the conveying direction). The longitudinal stretching direction is also the winding direction of the optical film 100. The optical film 100 is usually shipped in a wound state, and the winding direction is the direction in which the optical film 100 is wound forward towards the winding shaft after processing, which is also the extension direction of the optical film 100. The direction perpendicular to the winding direction is the width direction of the optical film 100.

[0057] In some embodiments, please refer to Figure 2 The optical film 100 includes a functional layer 110, which includes a substrate 111 and particles 112 dispersed in the substrate 111. The optical film 100 of this application has a depolarization function. When linearly polarized light is incident on the optical film 100, the optical film 100 can convert the linearly polarized light into circularly polarized light and / or elliptically polarized light, thereby achieving a depolarization effect.

[0058] The optical film 100 of this application (with a slow axis angle of 5° to 55°) has a higher slow axis angle compared to existing high-retardation films (with a slow axis angle close to 0°). Combined with the scattering effect of the particles 112 on the incident polarized light, it can achieve roll-to-roll bonding with the polarization layer 210 and also has excellent depolarization function. Furthermore, the optical film 100 of this application has lower cost and simpler manufacturing process compared to a quarter-wave plate.

[0059] In the actual production of optical film 100, due to process limitations, the slow axis angle of optical film 100 fluctuates in its width direction (i.e., the TD direction). That is, the slow axis angle may differ in different regions of optical film 100 in the width direction. However, in the transport direction (i.e., the MD direction), because optical film 100 is produced continuously at a high speed, the slow axis angle of optical film 100 remains essentially continuous in the transport direction. Therefore, this application adjusts the slow axis angle of optical film 100 in the width direction to improve the slow axis angle, thereby achieving roll-to-roll bonding and good polarization correction.

[0060] In some embodiments, in the optical film 100, the area of ​​the region with a slow axis angle range of 5° to 55° accounts for 10% to 100% of the total area of ​​the optical film 100, and the region with a slow axis angle range of 5° to 55° can be one or more regions. It is understood that the percentage of the area of ​​the region with a slow axis angle range of 5° to 55° to the total area of ​​the optical film 100 can be any value between 10% and 100%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc. In actual production, due to process limitations, the slow axis angle of different regions of the optical film 100 fluctuates, making it difficult to achieve a consistently high slow axis angle across all regions. Therefore, ensuring that at least some regions of the optical film 100 have a slow axis angle of 5° to 55° is sufficient to achieve roll-to-roll alignment while guaranteeing polarization correction. Of course, the larger the area of ​​the slow axis angle range of 5° to 55°, the better the depolarization effect of the optical film 100, and the closer the slow axis angle is to 45°, the better the depolarization effect.

[0061] In some embodiments, in multiple regions of the optical film 100, at least one region has a slow axis angle ranging from 35° to 55°. It is understood that the slow axis angle of this region can be any angle between 35° and 55°, such as 35°, 37°, 40°, 42°, 45°, 47°, 50°, 52°, 55°, etc.; or, the slow axis angle of this region can fluctuate between 35° and 55°. For example, the slow axis angle is different at different locations in this region, but the slow axis angle at different locations is within the range of 35° to 55°. When the optical film 100 and the polarizing layer 210 are bonded, the depolarization effect is optimal when the angle between the slow axis of the optical film 100 and the transmission axis of the polarizing layer 210 is approximately 45 degrees. When this angle is exactly 45 degrees, the light is converted into circularly polarized light after passing through both the polarizing layer 210 and the optical film 100. However, when the angle deviates from 45 degrees, a phase difference occurs between the fast and slow axes, resulting in elliptically polarized light after passing through the optical film 100. In actual production, achieving an absolute 45-degree angle between the slow axis of the optical film 100 and the transmission axis of the polarizing layer 210 requires sophisticated equipment and processes, leading to increased costs. This application sets the slow axis angle of the optical film 100 in the range of 45±10°, which can satisfy the roll-to-roll bonding of the optical film 100 and the polarization layer 210, achieve a better depolarization effect, and at the same time adapt to existing processes, avoiding increased process costs.

[0062] Preferably, the slow axis angle of at least one region is in the range of 40° to 50°; more preferably, the slow axis angle of at least one region is in the range of 42° to 47°; most preferably, the slow axis angle of at least one region is in the range of 45°, so as to achieve a better debiasing effect.

[0063] In some embodiments, the slow axis angle of multiple regions in the optical film 100 is in the range of 35° to 55°, that is, the slow axis angle of the entire optical film 100 is in the range of 35° to 55°. When the slow axis angle of the entire optical film 100 is in the range of 35° to 55°, each region of the optical film 100 can be used for the polarizer 200 to achieve a better depolarization effect of the polarizer 200 and improve the utilization rate of the optical film 100.

[0064] In some embodiments, please refer to Figure 1The optical film 100 includes a first region A1, a second region A2, and a third region A3. The first region A1 and the third region A3 are located on opposite sides of the second region A2 in the transverse stretching direction. The slow axis angle of the first region A1 is greater than that of the second region A2, and the slow axis angle of the third region A3 is greater than that of the second region A2. Specifically, the slow axis angle of the first region A1 ranges from 5° to 55°, the slow axis angle of the second region A2 ranges from 0° to 55°, and the slow axis angle of the third region A3 ranges from 5° to 55°. Due to the stretching process, in the transverse stretching direction, the slow axis angle of the optical film 100 tends to be larger at both ends and smaller in the middle; that is, the slow axis angle near the edge of the film is larger than that near the center. In some cases, such as... Figures 8-10 As shown, in the wide direction of the optical film 100, from the edge of the film to the center, the slow axis angle of the region between the edge and the center of the film shows a decreasing trend.

[0065] In some embodiments, the slow axis angle of the first region A1 may also be equal to the slow axis angle of the second region A2, and the slow axis angle of the third region A3 may also be equal to the slow axis angle of the second region A2.

[0066] It is understandable that the first region A1 may include one or more regions on the side away from the second region A2, and one or more regions may also be included between the first region A1 and the second region A2; the third region A3 may also include one or more regions on the side away from the second region A2, and one or more regions may also be included between the third region A3 and the second region A2.

[0067] In some embodiments, please refer to Figure 1 In the width direction (TD) of the optical film 100, the optical film 100 has a first edge L1 and a second edge L2. The first region A1 can be the region near the first edge L1, and the second region A2 can be the region near the second edge L2. That is, the first region A1 and the second region A2 are the edge regions of the optical film 100 on opposite sides in the width direction. The slow axis angle of at least one of the first region A1 and the third region A3 is in the range of 35° to 55°. In actual production, it is difficult to achieve a uniform slow axis angle in all regions of the optical film 100. It is common to see the slow axis angle in the width direction as described above, which is high at both ends and low in the middle. In this case, in order to select a suitable optical film 100 for use in a polarizer, the produced optical film 100 is cut, and the part of the region with the required slow axis angle is selected for use in the polarizer. The first region A1 and the third region A3 are located at the edge of the optical film 100, and the slow axis angle is in the range of 35° to 55°. This facilitates cutting and meets the requirement of good depolarization effect of the polarizer.

[0068] In some embodiments, the optical film 100 is formed using a biaxial stretching process. The orientation differences of the film's molecular chains in the TD and MD directions are controlled through transverse (TD) stretching and longitudinal (MD) stretching, thereby precisely adjusting the directions of the slow and fast axes of the film. The transverse stretching ratio λ of the optical film 100 is... TD With longitudinal stretch ratio λ MD The relation satisfies: λ TD / λ MD <3, preferred, 0<λ TD / λ MD ≤2, more preferably, 0.5≤λ TD / λ MD ≤1.5, for example, λ TD / λ MD The values ​​can be 0.5, 0.75, 1, 1.25, 1.5, etc. The lateral stretching ratio λ of the optical film 100 is... TD With longitudinal stretch ratio λ MD When the ratio is within the above range, the slow axis angle of at least one region of the optical film 100 can be in the range of 5° to 55°.

[0069] In some embodiments, the in-plane retardation value R0 of the optical film 100 is less than 3000 nm. This application uses an optical film 100 with a low in-plane retardation value, and at the same time, it is combined with particles 112 to achieve a good depolarization effect while avoiding the generation of rainbow patterns in the optical film 100.

[0070] In some embodiments, since the in-plane retardation value R0 of the optical film 100 is R0 = (n x -n y )×d, where n x Let n be the refractive index along the slow axis of optical film 100. y The refractive index n along the fast axis of optical film 100 y d is the thickness of the optical film 100, n x With n y The relation satisfies: n x -n y <0.06, to avoid rainbow patterns from appearing on the optical film 100.

[0071] In some embodiments, please refer to Figure 5The functional layer 110 includes a first sublayer 1101, a second sublayer 1102, and a third sublayer 1103 sequentially disposed along the thickness direction of the optical film 100. Each of the first sublayer 1101, second sublayer 1102, and third sublayer 1103 contains the substrate 111, and at least one of the first sublayer 1101, second sublayer 1102, and third sublayer 1103 contains particles 112. Any one of the first sublayer 1101, second sublayer 1102, and third sublayer 1103 may contain particles 112, or any two layers may contain particles 112, or all three layers may contain particles 112. It is understood that the functional layer 110 of this application can be formed by co-extrusion molding of three layers of polymer melt, and the particles 112 can be disposed in any one or more layers; this application does not impose any limitations.

[0072] In one embodiment, please refer to Figure 5 The functional layer 110 includes a first sublayer 1101, a second sublayer 1102, and a third sublayer 1103 arranged sequentially along the thickness direction of the optical film 100. The first sublayer 1101 includes a substrate 111 and particles 112 dispersed in the substrate 111. The second sublayer 1102 includes the substrate 111 (but does not include particles 112). The third sublayer 1103 includes the substrate 111 and particles 112 dispersed in the substrate 111, so that the functional layer 110 has uniform optical performance and improves the depolarization effect of the functional layer 110.

[0073] In some embodiments, the material of the substrate 111 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 polyethylene terephthalate, modified or unmodified polycarbonate, copolymers of polyethylene terephthalate, and blends of polyethylene terephthalate; for example, polyethylene terephthalate (PET), polyethylene naphthalate (PET). At least one of, but not limited to, selected from the following: a copolymer of phthalate (PEN), poly(ethylene terephthalate-ethylene isophthalate), a blend of phthalate and poly(ethylene terephthalate-ethylene isophthalate), a blend of phthalate and 1,4-cyclohexanediol, and a blend of phthalate and polycarbonate. The optical film 100 using the aforementioned substrate 111 is less expensive than a quarter-wave plate.

[0074] In some embodiments, particle 112 may be a birefringent particle, wherein the ordinary refractive index n of the birefringent particle is... o With unusual light refractive index ne The relation satisfies: n o -n e <0.2, to ensure that particle 112 has a good scattering effect and depolarization performance, and to avoid the scattering intensity difference between the two being too large, which would affect the depolarization effect and optical performance such as transmittance.

[0075] In some embodiments, particles 112 can be inorganic or organic particles. Inorganic particles include at least one of silicon dioxide, titanium dioxide, and calcium carbonate, while organic particles can be organosilicon, but are not limited thereto. In this application, particles 112 can be uniformly dispersed in the substrate 111 to ensure the uniformity of the depolarization effect.

[0076] In some embodiments, the thickness of the optical film 100 ranges from 10 μm to 60 μm. It is understood that the thickness of the optical film 100 can be any value between 10 μm and 60 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, etc. The thickness of the optical film 100 is within the above range to ensure good depolarization effect and bonding performance. If the thickness of the optical film 100 is too thin, it will result in uneven bonding with other film layers in the polarizer. If the thickness of the optical film 100 is too thick, the raw material cost will increase, and it will be detrimental to the thinner design of the polarizer.

[0077] In some embodiments, please refer to Figure 3 and Figure 4 The optical film 100 further includes an adhesive layer 120, which is disposed on at least one side of the functional layer 110. For example, please refer to... Figure 3 The adhesive layer 120 may be located on one side of the functional layer 110; or, please refer to Figure 4 An adhesive layer 120 is provided on each of the opposite sides of the functional layer 110. The material of the adhesive layer 120 includes at least one of polyurethane or polyacrylate, but is not limited to this. The adhesive layer 120 serves to protect the optical film 100 and also serves to bond the upper and lower film layers.

[0078] In some embodiments, the adhesive layer 120 may be a coating formed on the surface of the functional layer 110 and prepared by a coating process.

[0079] Furthermore, the adhesive layer 120 may also include particles 112 as described above, such as birefringent particles, to also have a depolarization effect.

[0080] This application also provides a polarizer 200, please refer to... Figure 6The polarizer 200 includes a polarizing layer 210 and an optical film 100. The optical film 100 is disposed on one side of the polarizing layer 210; wherein, the optical film 100 is the optical film 100 described above.

[0081] In some embodiments, please refer to Figure 6 The polarizer 200 also includes a compensation layer 220, which is disposed on the side of the polarizing layer 210 away from the optical film 100 to provide protection and compensation for the polarizing layer 210 and improve the optical performance of the polarizer 200. The compensation layer 220 may be a cellulose triacetate film, but is not limited thereto.

[0082] In some embodiments, in the polarizer 200 of this application, the slow axis angle of each region of the optical film 100 can be in the range of 35° to 55°. It is understood that the slow axis angle of each region of the optical film 100 can be any angle between 35° and 55°, such as 35°, 37°, 40°, 42°, 45°, 47°, 50°, 52°, 55°, etc. Alternatively, the slow axis angle of each region can fluctuate between 35° and 55°. For example, the slow axis angle is different at different positions of the region, but the slow axis angle at different positions is within the range of 35° to 55°.

[0083] Furthermore, the angle between the slow axis of the optical film 100 and the transmission axis of the polarizing layer 210 is in the range of 35° to 55°. It can be understood that the angle between the slow axis of the optical film 100 and the transmission axis of the polarizing layer 210 can be any angle between 35° and 55°, such as 35°, 37°, 40°, 42°, 45°, 47°, 50°, 52°, 55°, etc.

[0084] Since the depolarization effect is better when the angle between the slow axis of the optical film 100 and the transmission axis of the polarization layer 210 is 45±10° when the optical film 100 and the polarization layer 210 are bonded, the roll-to-roll bonding of the optical film 100 and the polarization layer 210 is more conducive when the slow axis angle of the optical film 100 reaches 45±10°, and at the same time, a better depolarization effect is achieved.

[0085] In some embodiments, the maximum brightness of light passing through the polarizer 200 is L. max Minimum brightness is L min L max / L min Also known as the debiasing ratio, L max / L min The range is 1 to 20; preferably, L max / L min The range is 1 to 10; more preferably, L max / L min The range is 1 to 5, with L being the most preferred.max / L min The range is 1 to 2. Among them, the depolarization ratio (L) max / L min The closer the value is to 1, the better the depolarization effect of polarizer 200.

[0086] In some embodiments, please refer to Figure 6 The polarizer 200 also includes a functional coating 230, which is disposed on the side of the optical film 100 away from the polarizing layer 210. The functional coating 230 includes at least one of an anti-glare coating, a hardening coating, an anti-reflective coating, an anti-fingerprint coating, and an anti-static coating.

[0087] Furthermore, the haze range of the functional coating 230 is 1% to 50%. It can be understood that the haze of the functional coating 230 can be any value between 1% and 50%. For example, the haze of the functional coating 230 can be 1%, 3%, 5%, 7%, 10%, 20%, 30%, 40%, 50%, etc. Specifically, the appropriate haze can be selected according to the actual function of the functional coating 230.

[0088] This application also provides a display device 10, please refer to... Figure 7 The display device 10 of this application includes a display panel 300 and a first polarizer 201. The first polarizer 201 is disposed on the light-emitting side of the display panel 300, wherein the first polarizer 201 is a polarizer 200 as described above.

[0089] The display panel 300 may be a liquid crystal display panel, but is not limited thereto. The display panel 300 may include a first substrate and a second substrate disposed opposite to each other, and a liquid crystal layer located between the first substrate and the second substrate.

[0090] In some embodiments, please refer to Figure 7 The first polarizer 201 includes an optical film 100, a first polarizing layer 211, and a first compensation layer 221. The first compensation layer 221 is located on the side of the first polarizing layer 211 away from the optical film 100, and the first compensation layer 221 is disposed close to the display panel 300.

[0091] In this application, the first polarizer 201 uses the optical film 100 as the base layer. The first compensation layer 221, the first polarizing layer 211 and the optical film 100 are rolled together and then bonded to the display panel 300. This can reduce at least one layer of base material, reduce the thickness of the first polarizer 201, and the optical film 100 can replace the existing 1 / 4 wave plate to achieve the depolarization function, thereby reducing the cost of the film material.

[0092] In some embodiments, the first polarizer 201 further includes a functional coating 230, which is located on the side of the optical film 100 away from the polarizing layer 210. The functional coating 230 may include one or more coatings, for example, the functional coating 230 may include at least one of an anti-glare coating, a hardening coating, an anti-reflective coating, an anti-fingerprint coating, and an antistatic coating.

[0093] In some embodiments, please refer to Figure 7 The display device 10 further includes a second polarizer 202, which is disposed on the side of the display panel 300 away from the first polarizer 201. The second polarizer 202 includes a base layer 240, a second polarizing layer 212, and a second compensation layer 222. The second compensation layer 222 is located on the side of the second polarizing layer 212 away from the base layer and is disposed close to the display panel 300.

[0094] The performance of the optical film 100 and polarizer 200 of this application will be further described below through specific embodiments, but the scope of this application is not limited to the following embodiments.

[0095] Example 1

[0096] The optical film 1 includes a functional layer and an adhesive layer located on one side of the functional layer. The functional layer includes a substrate and particles dispersed in the substrate. The substrate is polyethylene terephthalate (PET), the particles are made of silica, and the adhesive layer is made of polyacrylate. Specific parameters are shown in Table 1.

[0097] Example 2

[0098] Optical film 2 includes a functional layer and an adhesive layer located on one side of the functional layer. The functional layer includes a substrate and particles dispersed in the substrate. The substrate is polyethylene terephthalate (PET), the particles are made of silica, and the adhesive layer is made of polyacrylate. The stretch ratio of optical film 2 is different from that of optical film 1. For specific parameters, please refer to Table 1.

[0099] Example 3

[0100] Optical film 3 includes a functional layer and an adhesive layer located on one side of the functional layer. The functional layer includes a substrate and particles dispersed in the substrate. The substrate is a blend of polyethylene terephthalate (PET) and polyethylene terephthalate-1,4-cyclohexanedimethyl ester (PETG) in a mass ratio of 10:1. The material of the particles is silica. The material of the adhesive layer is polyacrylate. The stretching ratio of optical film 3 is the same as that of optical film 2. For specific parameters, please refer to Table 1.

[0101] Comparative Example

[0102] The optical film 4 includes a substrate and an adhesive layer located on one side of the substrate. The substrate is made of polyethylene terephthalate (PET), and the adhesive layer is made of polyacrylate. The stretch ratio of the optical film 4 is different from that of the optical films 1 to 3. For specific parameters, please refer to Table 1.

[0103] Table 1

[0104]

[0105] Instructions for polarization correction effect testing: The polarization correction effect testing method is as follows: After attaching the optical film to the surface of the display panel, use a CA410 to test the polarization correction brightness (i.e., add another polarizer on the display panel with the optical film attached, rotate the polarizer 180° and test the brightness change), and measure the maximum brightness value as L. max The minimum brightness value is L min In Table 1, “○” indicates the debiasing ratio (L). max / L min When the value is between 1 and 2, the anti-polarization effect is good.

[0106] As shown in Table 1, the slow axis angles of the optical films in Examples 1 to 3 of this application are all within the range of 5° to 55°, which allows for roll-to-roll bonding with the polarization layer and provides good depolarization effect. max / L min =1~2), and the cost is lower than that of the comparative example; the slow axis angle of the optical film (high delay film) of the comparative example is close to 0°, which requires manual bonding at a 45° angle, and cannot achieve roll-to-roll bonding with the polarization layer, resulting in higher cost.

[0107] The slow axis angle curves of the optical films in Examples 1 to 3 and the comparative example were tested using an AXOSCAN phase difference meter. The test results are shown in the graphs. Figures 8-11 , where the horizontal axis represents the position of the optical film in the width direction, and the vertical axis represents the slow axis angle.

[0108] Depend on Figures 8-10 It can be seen that the slow axis angles of each region of the optical films in Examples 1 to 3 are all within the range of 5° to 55°. Furthermore, optical films 1 to 3 all exhibit a trend of higher slow axis angles in the two edge regions and lower slow axis angles in the middle region along the width direction. The slow axis angles in the two edge regions reach 35° to 55°, enabling roll-to-roll bonding with the polarization layer and providing a good depolarization effect. max / L min =1~2). Among them. Figure 10 and Figure 8 and Figure 9In comparison, the slow axis angle fluctuation is smaller, indicating that the optical film 3, which uses a blend of PET and PETG as the substrate, is more conducive to improving the overall slow axis angle balance of the optical film compared to the optical films 1 and 2, which use only PET as the substrate.

[0109] Depend on Figure 11 It can be seen that the slow axis angle of the comparative optical film is close to 0°, requiring manual bonding at a 45° angle, and cannot achieve roll-to-roll bonding with the polarizing layer.

[0110] It should be noted that the optical films used for bonding with the polarizing layer in Table 1 above are all film layers cut from the edge region of the optical film. Among them, Example 1 is a film layer with a slow axis angle of 42° cut from the edge region of optical film 1, Example 2 is a film layer with a slow axis angle of 45° cut from the edge region of optical film 2, Example 3 is a film layer with a slow axis angle of 45° cut from the edge region of optical film 3, and the comparative example is a film layer with a slow axis angle of 3° cut from the edge region of optical film 4.

[0111] This application provides an optical film, a polarizer, and a display device. The optical film includes a functional layer, which comprises a substrate and particles dispersed in the substrate. The optical film includes multiple regions, and at least one region has a slow-axis angle ranging from 5° to 55°. The slow-axis angle is the angle between the slow axis of the optical film and its lateral stretching direction. This application uses an optical film with a high slow-axis angle, which can be roll-to-roll bonded with the polarizing layer or other optical film layers in a polarizer, achieving excellent depolarization function.

[0112] 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.

[0113] 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.

[0114] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0115] 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 includes multiple regions, and the slow axis angle of at least one of the regions ranges from 5° to 55°, wherein the slow axis angle is the angle between the slow axis of the optical film and the transverse stretching direction of the optical film, and the transverse stretching direction is perpendicular to the winding direction of the optical film. The optical film includes a first region, a second region, and a third region, wherein the first region and the third region are located on opposite sides of the second region in the transverse stretching direction, and the slow axis angle of at least one of the first region and the third region ranges from 35° to 55°.

2. The optical film according to claim 1, characterized in that, The area of ​​the slow axis angle range of 5° to 55° accounts for 10% to 100% of the total area of ​​the optical film.

3. The optical film according to claim 1, characterized in that, The slow axis angle of the first region is greater than or equal to the slow axis angle of the second region, and the slow axis angle of the third region is greater than or equal to the slow axis angle of the second region; The slow axis angle of the second region ranges from 0° to 55°. The slow axis angle of the first region is in the range of 5° to 55°, or the slow axis angle of the third region is in the range of 5° to 55°.

4. The optical film according to claim 1, characterized in that, The slow axis angles of the multiple regions range from 35° to 55°.

5. The optical film according to claim 1, characterized in that, The lateral stretching ratio λ of the optical film TD With longitudinal stretch ratio λ MD The relation satisfies: λ TD / λ MD <3.

6. The optical film according to claim 1, characterized in that, The in-plane retardation value of the optical film is <3000 nm.

7. The optical film according to claim 1, characterized in that, The refractive index n along the slow axis of the optical film x Refractive index n along the fast axis y The relation satisfies: n x -n y <0.

06.

8. The optical film according to any one of claims 1-7, characterized in that, The optical film also includes: A functional layer, comprising a substrate and particles dispersed in the substrate; and An adhesive layer is disposed on at least one side of the functional layer.

9. The optical film according to claim 8, characterized in that, The functional layer includes a first sublayer, a second sublayer, and a third sublayer arranged sequentially along the thickness direction of the optical film. The first sublayer, the second sublayer, and the third sublayer all contain the substrate, and at least one of the first sublayer, the second sublayer, and the third sublayer contains the particles.

10. The optical film according to claim 9, characterized in that, The first sublayer contains the particles, and the third sublayer contains the particles.

11. The optical film according to claim 8, characterized in that, The particle is a birefringent particle, and the relationship between the ordinary light refractive index n o and the extraordinary light refractive index n e satisfies: n o - n e < 0.

2.

12. The optical film according to claim 8, characterized in that, The material of the substrate 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, and blends of polyethylene terephthalate; And / or, the material of the particles includes at least one of silicon dioxide, titanium dioxide, calcium carbonate, and organosilicon.

13. The optical film according to claim 8, characterized in that, The thickness of the optical film ranges from 10 μm to 60 μm.

14. A polarizer, characterized in that, include: Polarizing layer; An optical film is disposed on one side of the polarization layer; The optical film is an optical film as described in any one of claims 1-13.

15. The polarizer according to claim 14, characterized in that, The slow axis angle of each region of the optical film ranges from 35° to 55°. And / or, the angle between the slow axis of the optical film and the transmission axis of the polarizing layer is in the range of 35° to 55°.

16. The polarizer according to claim 14, characterized in that, The maximum brightness L of the polarizer max and minimum brightness L min The ratio L max / L min The range is from 1 to 20.

17. The polarizer according to claim 14, characterized in that, The polarizer also includes: A functional coating is disposed on the side of the optical film away from the polarization layer; The functional coating includes at least one of the following: anti-glare coating, hardening coating, anti-reflective coating, anti-fingerprint coating, and antistatic coating.

18. The polarizer according to claim 17, characterized in that, The haze of the functional coating ranges from 1% to 50%.

19. A display device, characterized in that, include: Display panel; The first polarizer is disposed on the light-emitting side of the display panel. The first polarizer is a polarizer as described in any one of claims 14-18.

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