Optical diffusion film and polarizing sheet

Abstract

SOLUTION: The present disclosure provides an optical diffusion film and a polarizing plate, the optical diffusion film 100 includes a polymer film layer 101 and grains 102 dispersed in the polymer film layer 101, the grains 102 include a crystallization seed and a polymer crystal 1022 attached to a surface of the crystallization seed, and the crystallization seed is a crystallization inducing agent 1021.EFFECT: The optical diffusion film and the polarizing sheet provided by the present disclosure can enlarge the viewing angle of the display device and improve the problems of color shift and rainbow pattern.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to the field of display technology, and more particularly to optical diffusion films and polarizing sheets. [Background technology]

[0002] Traditionally, vertical alignment (VA) liquid crystal display technology has been widely applied to large-size liquid crystal display panels (LCDs) due to its higher contrast, excellent color quality, good black particle size, black uniformity, and wide color gamut, and is gradually becoming the mainstream in the current market.

[0003] However, VA LCD panels have an obvious problem: their viewing angles are small. When the viewing angle is large, the images on VA LCD panels have a certain color shift, which affects the user's viewing experience. As consumers' requirements for image quality from LCD panels become increasingly strict, it is of great significance to reduce the color shift and improve the chromaticity viewing angle of VA LCD panels. Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an optical diffusion film and a polarizing sheet, which can widen the viewing angle of a display device and improve the problems of color shift and rainbow pattern. [Means for solving the problem]

[0005] The present disclosure provides an optical diffusion film, which includes a polymer film layer and crystal grains dispersed in the polymer film layer, the crystal grains including crystal nuclei and polymer crystal bodies attached to the surfaces of the crystal nuclei, and the crystal nuclei are a crystal inducer.

[0006] The present disclosure provides a polarizing sheet, comprising: a first polarizing layer; and a first protective layer disposed on the first polarizing layer and including an optical diffusion film, the optical diffusion film including a polymer film layer and crystal grains dispersed in the polymer film layer, the crystal grains including crystal nuclei and polymer crystals attached to the surfaces of the crystal nuclei, the crystal nuclei being a crystal inducer, the crystal grains being elongated, and the major axis of the crystal grains being parallel to the absorption axis of the first polarizing layer.

[0007] In some embodiments, the crystal grains are elongated, and the angle between the long axis of the crystal grains and the tensile direction of the polymer film layer is in the range of 0° to 60°.

[0008] In some embodiments, the crystallization inducer is an organic particle or an inorganic particle, and the particle size of the crystallization inducer is in the range of 100 nm to 100 μm.

[0009] In some embodiments, the material of the optical diffusion film includes the polymer and the crystallization inducer, and the mass of the crystallization inducer is 0.001% to 10% of the total mass of the polymer and the crystallization inducer.

[0010] In some embodiments, the polarizing sheet further includes a release film, a second protective layer, and an adhesive layer, wherein the release film is disposed on the side of the first protective layer away from the first polarizing layer, the second protective layer is disposed on the side of the first polarizing layer away from the first protective layer, and the adhesive layer is disposed on the side of the second protective layer away from the first polarizing layer.

[0011] In some embodiments, the retardation value of the optical diffusion film ranges from 0 nm to 200 nm. [Effects of the Invention]

[0012] The present disclosure provides an optical diffusion film and a polarizing sheet, which include a polymer film layer and crystalline grains dispersed in the polymer film layer. The present disclosure adds a crystallization inducer to the polymer, which acts as a crystal nucleus during film formation, inducing the surrounding polymer to form crystals. The optical diffusion film is applied to a polarizing sheet and is placed on a polarizing layer. When the long axis of the crystal grains in the optical diffusion film is parallel to the absorption axis of the polarizing layer, the polarization direction of polarized light is perpendicular to the long axis of the crystal grains, and the polarized light is scattered at a large angle in a predetermined direction, thereby widening the viewing angle and reducing the color shift problem. Furthermore, adding a crystallization inducer to the polymer can reduce the retardation value of the optical diffusion film and reduce the rainbow effect. Therefore, the optical diffusion film and polarizing sheet provided by the present disclosure can effectively widen the viewing angle of a display device and reduce the color shift and rainbow effect problems. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic plan view of an optical diffusion film provided by an embodiment of the present disclosure. [Figure 2] 1 is a schematic plan view of an optical diffusion film provided by an embodiment of the present disclosure before being stretched. FIG. [Figure 3] 1 is a microscopic view of an optical diffusion film provided by an embodiment of the present disclosure. [Figure 4] FIG. 4 is a locally enlarged view of FIG. 3. [Figure 5] 1 is a schematic diagram of a cross-sectional structure of a polarizing sheet provided by an embodiment of the present disclosure. [Figure 6] FIG. 2 is a schematic diagram of a cross-sectional structure of a first protective layer according to a first embodiment of the present disclosure. [Figure 7] FIG. 2 is a schematic diagram of a cross-sectional structure of a first protective layer of a second type provided by an embodiment of the present disclosure. [Figure 8] FIG. 2 is a schematic diagram of a cross-sectional structure of a first protective layer according to a third embodiment of the present disclosure. [Figure 9] 1 is a schematic diagram of a cross-sectional structure of a display device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The technical solutions of the embodiments of the present disclosure will be described below in conjunction with the drawings of the embodiments of the present disclosure.

[0015] This disclosure may repeatedly refer to different embodiments by numbers and / or letters; this repetition is for purposes of simplicity and clarity and does not in itself indicate a relationship between the various implementations and / or configurations discussed.

[0016] 1, the present disclosure provides an optical diffusion film 100, which includes a polymer film layer 101 and crystal grains 102 dispersed in the polymer film layer 101. The crystal grains 102 include crystal nuclei and polymer crystals 1022 attached to the surfaces of the crystal nuclei, the crystal nuclei being a crystal inducer 1021, and the polymer crystals 1022 being formed by the crystallization of the polymer.

[0017] In the present disclosure, a crystallization inducer 1021 is added to the polymer, and a thin film slice containing the crystallization inducer 1021 is fabricated through a film-forming process. During a stretching process, the polymer molecules crystallize around the crystallization inducer 1021 along the stretching direction, forming crystal grains 102 with the crystallization inducer 1021 as the crystal nucleus. The crystal grains 102 have an elongated shape, such as, but not limited to, a rod shape, an oval sphere shape, or a rectangle shape. When the optical diffusion film 100 is applied to an optical film layer of a display panel, it can widen the viewing angle of polarized light.

[0018] In some embodiments, the crystal grains 102 are elongated and have a single long axis direction, and the included angle between the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 ranges from 0° to 60°. In the optical diffusing film 100, the included angle between the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 may be 0°. That is, the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 are parallel, and due to the anisotropy of the crystal grains, the long axis direction of the crystal grains 102 may deviate from the tensile direction by a certain angle. Furthermore, the included angle between the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 ranges from 0° to 30°. Furthermore, the included angle between the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 ranges from 0° to 10°. Furthermore, the angle between the long axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 is in the range of 0° to 5°. When the long axis direction of the crystal grains 102 and the extension direction of the polymer film layer 101 are parallel or the angle between the long axis direction of the crystal grains 102 and the extension direction of the polymer film layer 101 is small, the long axis direction of the crystal grains 102 and the extension direction are generally almost the same, which is advantageous for widening the viewing angle of polarized light.

[0019] In the present disclosure, the material of the optical diffusion film 100 includes the polymer and the crystallization inducer 1021. The polymer is the main raw material of the optical diffusion film 100 and is used for film formation. The crystallization inducer 1021 is an additive that is used to induce crystallization of the polymer.

[0020] In some embodiments, the polymer may be at least one of, but not limited to, Polymethyl Methachylate (PMMA), Polyethylene terephthalate (PET), Polycarbonate (PC), Cyclo Olefin Polymer (COP), Copolymers of Cycloolefin (COC), or Polystyrene (PS).

[0021] In some embodiments, the crystallization inducer 1021 may be solid particles. Because the polymer itself has difficulty forming crystal nuclei, the present disclosure adds particulate crystallization inducer 1021 to the polymer, and uses the crystallization inducer 1021 as a crystal nucleus, thereby inducing and promoting the aggregation and crystallization of polymer molecules around the crystallization inducer 1021, thereby forming polymer crystals 1022.

[0022] Here, the crystallization inducer 1021 may be organic particles or inorganic particles. When the crystallization inducer 1021 is organic particles, the material of the crystallization inducer 1021 may be, but is not limited to, polystyrene, polyethylene, polypropylene, etc. When the crystallization inducer 1021 is inorganic particles, the material of the crystallization inducer 1021 may be, but is not limited to, calcium carbonate, silica, zirconium oxide, magnesium carbonate, calcium sulfate, magnesium sulfate, barium carbonate, barium sulfate, etc. The shape of the crystallization inducer 1021 may include, but is not limited to, a sphere, a cube, a rectangular parallelepiped, a needle, a rod, etc.

[0023] In some embodiments, the particle size of the crystal inducer 1021 is in the range of 100 nm to 100 μm. Preferably, the particle size of the crystal inducer 1021 is in the range of 1 μm to 10 μm. When the particle size of the crystal inducer 1021 is within this range, it contributes to the formation of crystals in the polymer, thereby contributing to the widening of the viewing angle and the improvement of the rainbow pattern. If the particle size of the crystal inducer 1021 is too small, the effects of widening the viewing angle and improving the rainbow pattern of the optical diffusion film 100 are poor. If the particle size of the crystal inducer 1021 is too large, the transmittance of the optical diffusion film 100 is reduced, which further affects the transmittance of the display panel or display device.

[0024] In some embodiments, the raw materials of the optical diffusion film 100 include the polymer and the crystal inducer 1021, and the mass of the crystal inducer 1021 is 0.001% to 10% of the total mass of the polymer and the crystal inducer 1021. When the content of the crystal inducer 1021 is within the above range, the optical diffusion film 100 has better viewing angle widening and rainbow pattern improvement effects. When the content of the crystal inducer 1021 is less than 0.001%, the optical diffusion film 100 has poor viewing angle widening and rainbow pattern improvement effects or no viewing angle widening and rainbow pattern improvement effects. When the content of the crystal inducer 1021 is more than 10%, the transmittance of the optical diffusion film 100 decreases, further affecting the transmittance of the display panel or display device.

[0025] The present disclosure further provides a method for manufacturing the optical diffusion film 100. The method for manufacturing the optical diffusion film 100 includes the following steps.

[0026] S1: The polymer and the crystallization inducer 1021 are mixed and added to a film-forming device to obtain a polymer film slice containing the crystallization inducer 1021.

[0027] Here, the film formation process can be a casting process, in which the crystallization inducer 1021 is added to a casting apparatus together with polymer particles and melted, and a polymer film slice containing the crystallization inducer 1021 is obtained by casting. Referring to Figure 2, Figure 2 shows the structure of the polymer film slice, in which the crystal grains 102 are not formed.

[0028] S2: At a certain temperature, the polymer film slice is stretched in a predetermined direction to obtain the optical diffusion film 100 containing the crystal grains 102.

[0029] Here, the tensile temperature range of the polymer film slice is 150°C to 250°C.

[0030] At high temperatures, the polymer molecules grow and crystallize near the crystal nuclei, forming crystal grains 102 with the crystal inducer 1021 as the crystal nuclei. At the same time, under tension, the polymer molecules crystallize along the tensile direction X, forming crystals 1022 extending along the tensile direction X, with the crystal grains 102 having a major axis along the tensile direction X. Referring to FIG. 1, FIG. 1 shows the structure of the optical diffusion film 100, with the crystal grains 102 already formed. As shown in FIG. 1, the crystal grains 102 are elongated, e.g., elliptical, with the major axis of the ellipse being the major axis of the crystal grains 102. The major axis of the crystal grains 102 is the same as the tensile direction X, and the crystal nuclei are located at the centers of the ellipses.

[0031] Referring to Figures 3 and 4, these are microscopic views of the optical diffusion film of the present application. As can be seen from Figure 3, a large number of the crystal grains 102 are distributed in the polymer film layer 101, and as can be seen from the locally enlarged view of Figure 4, the crystal grains 102 include a crystal nucleus and a crystal body 1022 attached to the surface of the crystal nucleus.

[0032] 5, the present disclosure further provides a polarizing sheet 200. The polarizing sheet 200 includes a first polarizing layer 120 and a first protective layer 110.

[0033] The first polarizing layer 120 is used for filtering and adjusts the polarization to display an image on the LCD panel. The material of the first polarizing layer 120 includes, but is not limited to, polyvinyl alcohol (PVA).

[0034] The first protective layer 110 is disposed on the first polarizing layer 120, i.e., on the light exit surface of the first polarizing layer 120, and is used to protect the first polarizing layer 120 while widening the viewing angle. The first protective layer 110 includes the optical diffusion film as described above, and the optical diffusion film 100 is disposed on the light exit surface of the first polarizing layer 120.

[0035] The optical diffusion film 100 includes a polymer film layer 101 and crystal grains 102 dispersed in the polymer film layer 101. The crystal grains 102 include crystal nuclei and polymer crystals 1022 attached to the surfaces of the crystal nuclei, the crystal nuclei being a crystal inducer 1021, and the polymer crystals 1022 are formed by crystallization of the polymer. The crystal grains 102 are elongated, and the major axis of the crystal grains 102 is parallel to the absorption axis of the first polarizing layer 120.

[0036] Here, the angle between the major axis direction of the crystal grains 102 and the tensile direction of the polymer film layer 101 is in the range of 0° to 30°.

[0037] In the present disclosure, polarized light emitted from the light exit surface of the first polarizing layer 120 passes through the optical diffusion film 100 before being emitted, thereby widening the viewing angle. Because the long axis direction of the crystal grains 102 is parallel to the absorption axis direction of the first polarizing layer 120, the polarization direction of the polarized light is perpendicular to the long axis direction of the crystal grains 102. When the polarized light hits the crystal grains 102, it is scattered toward a large angle, widening the left and right viewing angles. Therefore, providing the first protective layer 110 on the light exit surface of the first polarizing layer 120 has the effect of widening the viewing angle.

[0038] 6 , in some embodiments, the first protective layer 110 further includes a hard layer 111, which is disposed on the side of the optical diffusion film 100 that faces away from the first polarizing layer 120. The hardness of the hard layer 111 is greater than that of the optical diffusion film 100 and is used to improve the overall hardness and scratch resistance of the first protective layer 110.

[0039] The material of the hard film 111 includes a resin, a curing agent, a photoinitiator, a modifier, an organic solvent, etc. The mass ratio of each component in the material of the hard film 111 may be 5% to 30% resin, 0.1% to 5% curing agent, 0.1% to 5% photoinitiator, 0.1% to 10% modifier, and 10% to 40% organic solvent. The resin includes at least one of polysiloxane resin, polysilane resin, or fluororesin, etc. The curing agent includes at least one of melamine curing agent, (closed-type) isocyanate curing agent, or epoxy curing agent, etc. The photoinitiator includes at least one of radical initiator, acid-alkali catalyst, metal catalyst, etc., but is not limited to these.

[0040] 6 to 8 in the present disclosure, the first protective layer 110 may further include at least one of a reflection-reducing film 114, an anti-glare film 112, and an anti-fingerprint film 113. The reflection-reducing film 114, the anti-glare film 112, or the anti-fingerprint film 113 may be disposed on the side of the optical diffusion film 100 that is farther from the first polarizing layer 120, or the reflection-reducing film 114, the anti-glare film 112, or the anti-fingerprint film 113 may be disposed on the side of the hard film 111 that is farther from the optical diffusion film 100, and this is not limited thereto.

[0041] In some embodiments, referring to FIG. 7, the first protective layer 110 includes the optical diffusion film 100 and the anti-fingerprint film 113, and the anti-fingerprint film 113 is disposed on the side of the optical diffusion film 100 away from the first polarizing layer 120.

[0042] In some embodiments, referring to FIG. 8 , the first protective layer 110 includes the light diffusion prevention film 100, the anti-glare film 112, and the anti-fingerprint film 113, and the anti-glare film 112 is disposed on the side of the light diffusion film 100 away from the first polarizing layer 120, and the anti-fingerprint film 113 is disposed on the side of the anti-glare film 112 away from the light diffusion film 100.

[0043] 6 , in some embodiments, the first protective layer 110 includes the optical diffusion film 100, the hard film 111, the reflection reduction film 114, and the anti-fingerprint film 113. Here, the hard film 111 is disposed on the side of the optical diffusion film 100 away from the first polarizing layer 120, the reflection reduction film 114 is disposed on the side of the hard film 111 away from the optical diffusion film 100, and the anti-fingerprint film 113 is disposed on the side of the reflection reduction film 114 away from the hard film 111.

[0044] 5 , in some embodiments, the polarizing sheet 200 further includes a release film 140, a second protective layer 130, and an adhesive layer 150. The release film 140 is disposed on a side of the first protective layer 110 away from the first polarizing layer 120, the second protective layer 130 is disposed on a side of the first polarizing layer 120 away from the first protective layer 110, and the adhesive layer 150 is disposed on a side of the second protective layer 130 away from the first polarizing layer 120. Here, the release film 140 is used to protect the first protective layer 110, and the adhesive layer 150 is used to adhere to the display panel. The adhesive layer 150 may be, but is not limited to, a pressure-sensitive adhesive.

[0045] In some embodiments, the retardation value of the optical diffusion film 100 ranges from 0 nm to 200 nm. The rainbow pattern is related to the retardation value of the optical diffusion film 100, and reducing the retardation value contributes to improving the rainbow pattern. After adding the crystal inducer 1021 to the optical diffusion film 100 of the present disclosure, the retardation value can be reduced. The higher the content of the crystal inducer 1021 in the optical diffusion film 100, the smaller the retardation value, and reducing the retardation value can improve the rainbow pattern. Therefore, the optical diffusion film 100 of the present disclosure has the effect of improving the rainbow pattern. When the retardation value of the optical diffusion film 100 is less than 200 nm, the rainbow pattern can be eliminated.

[0046] 9, the present disclosure further provides a display device 300. The display device 300 includes a backlight module 310, a first polarizing sheet 320, a display panel 330, and a second polarizing sheet 340.

[0047] The backlight module 310 is used to provide backlight to the display panel 330. The backlight module 310 may be a direct-type backlight module or a side-entry type backlight module, and is not limited thereto.

[0048] The first polarizing sheet 320 is disposed on the backlight module 310 and is used to convert the light beam emitted from the backlight module 310 into polarized light. The first polarizing sheet 320 may include a third protective layer, a second polarizing layer, and a fourth protective layer. Here, the second polarizing layer is located between the third protective layer and the fourth protective layer. The third protective layer may be attached to the backlight module 310 via a pressure-sensitive adhesive, and the fourth protective layer may be attached to the display panel 330 via a pressure-sensitive adhesive.

[0049] The display panel 330 is disposed on the side of the first polarizing sheet 320 away from the backlight module 310, and the display panel 330 may be, but is not limited to, a liquid crystal display panel 330 including an array substrate, a liquid crystal layer, and an opposing substrate.

[0050] The second polarizing sheet 340 is disposed on a side of the display panel 330 away from the first polarizing sheet 320. The second polarizing sheet 340 is the polarizing sheet 200 described in the above embodiment. The second polarizing sheet 340 is used to analyze polarized light electrically modulated by a liquid crystal layer and generate a light-dark contrast to generate a display screen. The second polarizing sheet 340 includes a first protective layer 110, a first polarizing layer 120, and a second protective layer 130. The first protective layer 110 is disposed on a side of the first polarizing layer 120 away from the display panel 330, and the second protective layer 130 is disposed on a side of the first polarizing layer 120 closer to the display panel 330.

[0051] In the present disclosure, the first protective layer 110 including the optical diffusion film 100 is disposed on the first polarizing layer 120 of the second polarizing sheet 340. Therefore, the optical diffusion film 100 includes the crystal grains 102, and the long axis direction of the crystal grains 102 is parallel to the absorption axis direction of the first polarizing layer 120. Therefore, the polarization direction of the polarized light is perpendicular to the long axis direction of the crystal grains 102. When the polarized light encounters the crystal grains 102, it is scattered toward a larger angle, thereby widening the viewing angle. Therefore, in the display device 300, the viewing angle of the light emitted through the second polarizing sheet 340 is widened, and the color shift problem can be further improved.

[0052] The optical diffusion film 100, the polarizing sheet 200, and the display device 300 provided in the present disclosure will be further described below with reference to specific examples and data.

[0053] The comparative example is an optically diffusing film formed from a polymer, in which no crystallization inducer is added.

[0054] In Examples 1 to 4, optical diffusion films are formed from different contents of crystal inducer and polymer.

[0055] Here, the polymer used in the optical diffusion films in the comparative example and Examples 1 to 4 was polyethylene terephthalate (PET), and the material of the crystal inducer in Examples 1 to 4 was calcium carbonate.

[0056] Table 1 shows the retardation values ​​of the optical diffusion films of the Comparative Example and Examples 1 to 4, as well as the rainbow pattern and viewing angle measurement results of the display devices using the optical diffusion films corresponding to the Comparative Example and Examples 1 to 4. TIFF2026002718000002.tif113159

[0057] As can be seen from the data in Table 1, the viewing angles corresponding to Examples 1 to 4, in which a crystal inducer was added, are larger than the viewing angles of the comparative examples in which no crystal inducer was added, demonstrating that the optical diffusion film of the present disclosure, to which a crystal inducer was added, has the effect of widening the viewing angle.

[0058] As can be seen from the data in Table 1, no rainbow pattern was observed in Examples 1 to 4, which contained a crystal inducer, while a rainbow pattern was observed in the control sample, which did not contain a crystal inducer. This demonstrates that the optical diffusion film containing the crystal inducer of the present disclosure has the effect of improving the rainbow pattern. The rainbow pattern is related to the retardation value of the optical diffusion film, and reducing the retardation value is beneficial for improving the rainbow pattern. Adding a crystal inducer to the optical diffusion film of the present disclosure can reduce the retardation value of the optical diffusion film. The higher the content of the crystal inducer in the optical diffusion film, the smaller the retardation value, and reducing the retardation value contributes to improving the rainbow pattern. Therefore, the optical diffusion film of the present disclosure has the effect of improving the rainbow pattern.

[0059] As described above, the present disclosure provides an optical diffusion film and a polarizing sheet, which include a polymer film layer and crystalline grains dispersed in the polymer film layer. The present disclosure adds a crystallization inducer to the polymer, which acts as a crystal nucleus during film formation, inducing the surrounding polymer to form crystals. When the optical diffusion film is applied to a polarizing sheet and placed on a polarizing layer, and the long axis of the crystal grains of the optical diffusion film is parallel to the absorption axis of the first polarizing layer, the polarization direction of polarized light is perpendicular to the long axis of the crystal grains, causing the polarized light to be scattered at a large angle in a predetermined direction, thereby expanding the viewing angle and reducing the color shift problem. Therefore, the optical diffusion film and polarizing sheet provided by the present disclosure can effectively expand the viewing angle of a display device and reduce the color shift and rainbow effect problems.

[0060] As described above, the present disclosure has been disclosed by preferred embodiments, but the above preferred embodiments do not limit the present disclosure, and those skilled in the art can make various modifications and adjustments without departing from the spirit and scope of the present disclosure, and therefore the scope of protection of the present disclosure is determined by the scope defined in the claims.

Claims

1. An optical diffusion film, a polymer film layer and crystal grains dispersed in the polymer film layer; The crystal grains include a crystal nucleus and a polymer crystal attached to the surface of the crystal nucleus, and the crystal nucleus is a crystal inducer. An optical diffusion film characterized by:

2. The crystal grains are elongated, and the angle between the long axis direction of the crystal grains and the tensile direction of the polymer film layer is in the range of 0° to 60°.

2. The optical diffusion film according to claim 1.

3. The crystal-inducing agent is an organic particle or an inorganic particle, and the particle size of the crystal-inducing agent is in the range of 100 nm to 100 μm.

2. The optical diffusion film according to claim 1.

4. the material of the optical diffusion film includes the polymer and the crystallization inducer, and the mass of the crystallization inducer is 0.001% to 10% of the total mass of the polymer and the crystallization inducer; 4. The optical diffusion film according to claim 1, wherein the optical diffusion film is a film having a thickness of 100 nm or less.

5. A polarizing sheet, a first polarizing layer; and a first protective layer disposed on the first polarizing layer, the first protective layer including an optical diffusion film; The optical diffusion film includes a polymer film layer and crystal grains dispersed in the polymer film layer, the crystal grains include crystal nuclei and polymer crystal bodies attached to the surfaces of the crystal nuclei, and the crystal nuclei are a crystal inducer; the crystal grains are elongated, and the long axis direction of the crystal grains is parallel to the absorption axis direction of the first polarizing layer; A polarizing sheet characterized by:

6. the angle between the long axis direction of the crystal grain and the tensile direction of the polymer film layer is in the range of 0° to 60°; 6. The polarizing sheet according to claim 5.

7. The crystal-inducing agent is an organic particle or an inorganic particle, and the particle size of the crystal-inducing agent is in the range of 100 nm to 100 μm.

6. The polarizing sheet according to claim 5.

8. the material of the optical diffusion film includes the polymer and the crystallization inducer, and the mass of the crystallization inducer is 0.001% to 10% of the total mass of the polymer and the crystallization inducer; 6. The polarizing sheet according to claim 5.

9. the polarizing sheet further includes a release film, a second protective layer, and an adhesive layer, the release film being disposed on a side of the first protective layer away from the first polarizing layer, the second protective layer being disposed on a side of the first polarizing layer away from the first protective layer, and the adhesive layer being disposed on a side of the second protective layer away from the first polarizing layer.

6. The polarizing sheet according to claim 5.

10. The retardation value of the optical diffusion film is in the range of 0 nm to 200 nm.

10. The polarizing sheet according to claim 5, wherein the polarizing sheet is a sheet having a thickness of 100 nm or less.

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