Depolarizing film based on liquid crystal material and manufacturing method thereof

Abstract

The invention relates to the technical field of depolarization films, in particular to a depolarization film based on a liquid crystal material and a manufacturing method of the depolarization film. The depolarization film is composed of at least two optical anisotropy areas including the first area and the second area. The average inclination angle of the liquid crystal layer in the area I relative to the horizontal plane is lt; the optical axis directions of the liquid crystal layers in the first area are the same, and the phase delay R0 of the liquid crystal layers in the first area is 200-350 nm; the liquid crystal layer in the second area has an average inclination angle gt relative to the horizontal plane; the optical axis directions of the liquid crystal layers in the second area are the same, and the phase delay R0 of the liquid crystal layers in the second area is lt; and 50 nm. The problems that the manufacturing process of the liquid crystal phase depolarizer is complex, the manufacturing cost is high, and the liquid crystal phase depolarizer is not suitable for roll-to-roll flexible film continuous production are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of depolarizing films, and specifically, to a depolarizing film based on liquid crystal materials and a manufacturing method thereof. Background Art

[0002] A depolarizing film is a functional optical film that realizes the conversion of polarized light to unpolarized light by regulating the polarization state distribution, and its core principle is based on the spatial / frequency domain modulation of the phase or polarization direction of incident light. With the increasing demand for refined polarization control in fields such as display technology, laser processing, and spectral detection, it can be used to suppress polarization mode dispersion (PMD) in dense wavelength division multiplexing (DWDM), suppress sample birefringence interference in optical coherence tomography (OCT), improve the diffraction efficiency of holographic display devices by integrating a depolarizing layer through a spatial light modulator, suppress the polarization noise of a magneto-optical trap by depolarization in a cold atom interferometer, and realize the output of quasi-natural light by integrating a depolarizing film on the surface of a display, etc.

[0003] Currently, the mainstream depolarizing devices can be divided into two categories: traditional crystal types and liquid crystal phase types. The traditional crystal types are represented by the Lyot type and the quartz optical rotation type. The liquid crystal phase type depolarizer has become an emerging direction with its flexible film form and large-area applicability. Its core principle is to achieve spatial depolarization through the random distribution of the optical axis angle or the phase retardation amount (such as segmented regions, multi-domain orientation). The liquid crystal phase type depolarizer has significant advantages in terms of flexibility potential, but it needs to overcome process bottlenecks. Japanese Patent Application JP2008226405A and Chinese Patent Application CN116400529A propose to use a random segmentation region design of the optical axis angle or thickness difference, but it requires multiple exposure processes and upper and lower substrate encapsulation, with complex processes and difficult mass production; US Patent US10585223B2 proposes an improved solution: using an isotropic / anisotropic hybrid region design, where the anisotropic region rotates polarized light and the isotropic region retains the original state, and simplifies the structure through the "pre-curing - local curing - heating - full curing" process. However, this process depends on step-by-step curing and heating, cannot be compatible with roll-to-roll continuous production, and the manufacturing cost is still high. Summary of the Invention

[0004] In a first aspect of the present invention, there is provided a depolarizing film based on liquid crystal materials. The depolarizing film is composed of at least two optically anisotropic regions, including Region 1 and Region 2; the average inclination angle of the liquid crystal layer in Region 1 with respect to the horizontal plane is <9°, the optical axis directions of the liquid crystal layers in Region 1 are the same, and the phase retardation R 0 value of the liquid crystal layer in Region 1 is 200 - 350 nm; the average inclination angle of the liquid crystal layer in Region 2 with respect to the horizontal plane is >81°, the optical axis directions of the liquid crystal layers in Region 2 are the same, and the phase retardation R 0 value of the liquid crystal layer in Region 2 is <50 nm.

[0005] The phase retardation R of the liquid crystal layer in Region 1 0 has a value of 230 - 310 nm; the phase retardation R of the liquid crystal layer in Region 2 0 has a value of < 30 nm.

[0006] The average inclination angle of the liquid crystal layer in Region 2 with respect to the horizontal plane > 85°.

[0007] The length and width dimensions of the liquid crystal layer cells in Region 1 < 80 μm.

[0008] Optionally, the length and width dimensions of the liquid crystal layer cells in Region 1 < 50 μm.

[0009] The ratio of the total area of Region 1 to Region 2 is 0.9 - 1.1.

[0010] The angle of the optical axis is ±45°.

[0011] It is found in this application that the average inclination angle of the liquid crystal molecules in Region 1 with respect to the horizontal plane < 9°, and by controlling the liquid crystal layer thickness d, the phase retardation R of the liquid crystal layer in Region 1 0 has a value of 200 - 350 nm, that is, close to 1 / 2 of the visible light wavelength, and can effectively rotate the transmitted linearly polarized light by 90°. At the same time, the liquid crystal molecules in Region 1 have the same optical axis angle, and with respect to the transmission direction of the external linearly polarized light, the optical axis angle ψ = ±45°.

[0012] Correspondingly, the average inclination angle of the liquid crystal molecules in Region 2 with respect to the horizontal plane > 81°. Under the condition of satisfying the same liquid crystal layer thickness d as in Region 1, the phase retardation R of the liquid crystal layer in Region 2 0 has a value < 50 nm, and Region 2 has only a slight influence on the external linearly polarized light.

[0013] It is found in this application that the ratio of the total area of Region 1 to Region 2 is 0.9 - 1.1. Under such conditions, the intensities of the linearly polarized light that has undergone a deflection of about 90° and the linearly polarized light that has not undergone deflection are almost equivalent, and in the overall effective area of light incidence, it becomes a substantially random polarization state. Macroscopically observed, the two cancel each other out to form a depolarization effect. The photo-alignment layer is used to form Region 1 and Region 2. By specific exposure energy, Region 1 and Region 2 have different orientation forces, inducing the inclination angle of the liquid crystal composition in Region 1 < 9° and in Region 2 > 81°.

[0014] The depolarizing film includes a photo-alignment layer and a liquid crystal composition layer, and the preparation raw materials of the photo-alignment layer include photo-alignment materials.

[0015] The photo-alignment materials include at least one of P1, P2, and P3.

[0016] P1: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy-4-[4-[4-[(E)-2-hexyloxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene];

[0017] P2: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy-6-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyl]-methyl-silylene];

[0018] P3: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy-4-4-[4-(E)-2-butoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-dimethyl-oxy-silylene].

[0019] The raw materials for preparing the liquid crystal composition layer include polymerizable liquid crystals, ester compounds containing 4-cyanobenzene groups, photoinitiators, and solvents.

[0020] The polymerizable liquid crystals include at least one of the following photopolymerizable groups: vinyl, vinyloxy, 1-chloroethylene, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, epoxyethanyl, oxetanyl, etc.

[0021] Optionally, the polymerizable liquid crystals include at least one of the following photopolymerizable groups: acryloyloxy, methacryloyloxy, vinyloxy, epoxyethanyl, and oxetanyl.

[0022] Optionally, the polymerizable liquid crystal includes acryloyloxy.

[0023] Optionally, the polymerizable liquid crystals include at least one of L1, L2, and L3.

[0024] L1: 4-(4-[6-(prop-2-enoyloxy)hexyloxy]benzoyloxy)phenyl 4-[6-(prop-2-enoyloxy)hexyloxy]benzoate;

[0025] L2: 3-methyl-4-(4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoyloxy)phenyl 4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoate;

[0026] L3: 5-Cyano-2,5-bis(4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoyloxy)benzoate.

[0027] The total amount of the polymerizable liquid crystal is 50 - 80 wt% of the liquid crystal composition.

[0028] Optionally, the total amount of the polymerizable liquid crystal is 55 - 70 wt% of the liquid crystal composition.

[0029] The ester compounds containing 4-cyanophenyl group include at least one of C1, C2, and C3.

[0030] C1: 4-(4-Cyanophenyl)phenyl 4-ethylcyclohexane-1-carboxylate;

[0031] C2: 4-(4-{[(4-Ethylcyclohexyl)oxy]carbonyl}phenyl)benzene-1-sulfonic acid;

[0032] C3: 4-[4-(4-Methylphenyl)benzoyloxy]benzoic acid.

[0033] The total amount of the ester compounds containing 4-cyanophenyl group is 20 - 50 wt% of the liquid crystal composition.

[0034] Optionally, the total amount of the ester compounds containing 4-cyanophenyl group is 30 - 45 wt% of the liquid crystal composition.

[0035] The photoinitiator includes at least one of photoinitiator TPO, photoinitiator TPO-L, photoinitiator 1173, photoinitiator 819, photoinitiator 651, photoinitiator 369, photoinitiator 184, photoinitiator 907, photoinitiator 207, photoinitiator 379, photoinitiator ITX, photoinitiator EDB, photoinitiator 1700, photoinitiator 1490, photoinitiator BP, diaryliodonium salts, triarylsulfonium salts, alkylsulfonium salts, iron arene salts, sulfonyloxy ketones and triarylsilyl ethers, benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2,4-dihydroxybenzophenone, thio-propoxy thioxanthone, isopropyl thioxanthone, and those produced by BASF such as Irgacure270 and Omnird784.

[0036] The total amount of the photoinitiator is 0.5 - 10 wt% of the polymerizable liquid crystal material.

[0037] Optionally, the total amount of the photoinitiator is 0.1 - 5 wt% of the polymerizable liquid crystal material.

[0038] The solvent includes at least one of ketones, acetates, alcohols, and cyclic esters.

[0039] Optionally, the ketone includes at least one of acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0040] Optionally, the acetate includes at least one of methyl acetate, ethyl acetate, butyl acetate, and methyl acetoacetate.

[0041] Optionally, the alcohol includes at least one of methanol, ethanol, isopropanol, and PGMEA (propylene glycol monomethyl ether acetate).

[0042] Optionally, the aromatic solvent includes at least one of toluene and xylene.

[0043] Optionally, the alicyclic hydrocarbon includes at least one of cyclopentane and cyclohexane.

[0044] Optionally, the halogenated hydrocarbon includes at least one of dichloromethane and chloroform.

[0045] Optionally, the cyclic ester includes γ-butyrolactone.

[0046] The second aspect of the present invention provides a method for preparing a depolarizing film based on a liquid crystal material, including the following steps:

[0047] S1, coating a photo-alignment material on the surface of a substrate, and drying to obtain an alignment layer;

[0048] S2, performing two exposures on the alignment layer to obtain an alignment layer including region one and region two, respectively;

[0049] S3, coating a liquid crystal composition containing a cyano group on the alignment layer including region one and region two, and drying and curing.

[0050] The dry coating amount of the alignment layer is 0.05 - 0.5 g / m 2 .

[0051] The energies of the two exposures are E1 and E2, respectively, where the energy of the exposure is E1 to obtain an alignment layer including region one, and the energy of the exposure is E2 to obtain an alignment layer including region two.

[0052] The E1:E2 ≥ 3.5, and the E1 ≥ 15 mJ / cm 2 .

[0053] The E1:E2 > 3.5, and the E1 > 15 mJ / cm 2 .

[0054] The E1 > 16.5 mJ / cm 2 .

[0055] Optionally, the E1 > 32 mJ / cm 2 .

[0056] Optionally, the coated photo-alignment material includes a solution of the coated photo-alignment material, and the content of the photo-alignment material in the solution of the photo-alignment material is 0.5-10% wt.

[0057] Optionally, the content of the photo-alignment material in the solution of the photo-alignment material is 0.5-5% wt.

[0058] The coating method includes at least one of spin coating, bar coating, and knife coating.

[0059] The coating method further includes printing technology.

[0060] Optionally, the printing technology includes at least one of screen printing, offset printing, roll-to-roll printing, letterpress printing, gravure printing, rotogravure printing, flexographic printing, intaglio printing, pad printing, heat-sealing printing, inkjet printing, printing with a stamper, and printing with a printing plate.

[0061] The substrate includes but is not limited to glass or plastic.

[0062] Optionally, the substrate includes at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl alcohol (PVA), polycarbonate (PC), triacetyl cellulose (TAC), cycloolefin polymer (COP), and color filter material.

[0063] Optionally, the color filter material includes at least one of triacetyl cellulose (TAC) and cycloolefin polymer (COP).

[0064] Beneficial effects

[0065] 1. The phase retardation R of the liquid crystal layer in Region 1 of the depolarizing film of the present application 0 is 230-310 nm; the phase retardation R of the liquid crystal layer in Region 2 0 is <30 nm.

[0066] 2. The liquid crystal phase depolarizing film of the present application involves two exposures, and the manufacturing process is simple and the manufacturing cost is low.

[0067] 3. The energies of the two exposures are E1 and E2 respectively. Among them, when the exposure energy is E1, an alignment layer including Region 1 is obtained, and when the exposure energy is E2, an alignment layer including Region 2 is obtained. By the two exposures, the inclination angles of Region 1 and Region 2 can be made different to produce a depolarizing effect.

[0068] 4. By defining E1:E2>3.5 and E1>16.5 mJ / cm 2 , the depolarization index can be made greater than 0.7.

[0069] 5. The liquid crystal phase depolarizing film of the present application is applicable to continuous production of roll-to-roll flexible films. Description of the Drawings

[0070] Figure 1 It is the mask in Example 1, where a is the first mask plate and b is the second mask plate. Detailed Description of the Invention

[0071] Examples 1-8, Comparative Examples 1-2

[0072] A depolarizing film based on liquid crystal material, the depolarizing film consists of two optically anisotropic regions: Region 1 and Region 2; the average inclination angle of the liquid crystal layer in Region 1 with respect to the horizontal plane is 4.2°, and the optical axis directions of the liquid crystal layers in Region 1 are the same; the average inclination angle of the liquid crystal layer in Region 2 with respect to the horizontal plane is 88.3°, and the optical axis directions of the liquid crystal layers in Region 2 are the same.

[0073] The depolarizing film includes an alignment layer and a liquid crystal composition layer, and the preparation raw materials of the alignment layer include photo-alignment materials.

[0074] A preparation method of a depolarizing film based on liquid crystal material, comprising the following steps:

[0075] S1, spin-coat a photo-alignment solution on the surface of the substrate, and after drying, obtain an alignment layer with a dry film coating amount of 0.054 g / m 2 ;

[0076] S2, use LPUV (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.), and through the first mask plate ( Figure 1 , a), perform the first exposure on the alignment layer, and the exposure energy E1 > 16.5 mJ / cm 2 , to obtain Region 1. Through the second mask plate (the complement of the first mask plate, Figure 1 , b), perform the second exposure on the alignment layer to obtain an alignment layer containing Region 1 and Region 2;

[0077] S3, spin-coat a liquid crystal composition layer on the alignment layer containing Region 1 and Region 2, with a dry film coating amount of 2.35 g / m 2 , and cure.

[0078] Region 1 and Region 2 are complementary, and the ratio of the total areas is 1.

[0079] The content of the photo-alignment material in the photo-alignment solution is 3 wt%, and the solvent is methyl ethyl ketone.

[0080] Among the raw materials for preparing the liquid crystal composition layers of Examples 1-3 and Comparative Examples 1-2, by weight ratio, L1:L2:C1:Photoinitiator 369:Cyclohexanone = 10:8:11:1:70; the photo-alignment material is P1; E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 40 μm.

[0081] Among the raw materials for preparing the liquid crystal composition layer of Example 4, by weight ratio, L1:L3:C2:Photoinitiator 369:Cyclohexanone = 14:6:9:1:70; the photo-alignment material is P2; E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 40 μm.

[0082] Among the raw materials for preparing the liquid crystal composition layer of Example 5, by weight ratio, L1:L3:C2:Photoinitiator 369:Cyclohexanone = 14:6:9:1:70; the photo-alignment material is P2; E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 25 μm.

[0083] Among the raw materials for preparing the liquid crystal composition layer of Example 6, by weight ratio, L1:L3:C3:Photoinitiator 369:Cyclohexanone = 14:7:8:1:70; the photo-alignment material is P3. E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 25 μm.

[0084] Among the raw materials for preparing the liquid crystal composition layer of Example 7, by weight ratio, L1:L3:C3:Photoinitiator 369:Cyclohexanone = 14:7:8:1:70; the photo-alignment material is P3; E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 5 μm.

[0085] Among the raw materials for preparing the liquid crystal composition layer of Example 8, by weight ratio, L1:L3:C3:Photoinitiator 369:Cyclohexanone = 14:4:12:1:70; the photo-alignment material is P3; E1 and E2 are 70 mJ / cm 2 and 10 mJ / cm 2 respectively; the cell sizes of the liquid crystal layers in Region 1 and Region 2 are both 5 μm.

[0086] P1: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonylvinyl]phenoxycarbonyl]phenoxy]butyl]-methylsilylene-co-oxy-4-[4-[4-[(E)-2-hexyloxycarbonylvinyl]phenoxycarbonyl]phenoxy]butyl]-methylsilylene];

[0087] P2: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonylvinyl]phenoxycarbonyl]phenoxy]butyl]-methylsilylene-co-oxy-6-[4-[4-[(E)-2-methoxycarbonylvinyl]phenoxycarbonyl]phenoxy]hexyl]-methylsilylene];

[0088] P3: Poly[oxy-4-[4-[4-[(E)-2-methoxycarbonylvinyl]phenoxycarbonyl]phenoxy]butyl]-methylsilylene-co-oxy-4-4-[4-(E)-2-butoxycarbonylvinyl]phenoxycarbonyl]phenoxy]butyl]-methylsilylene-co-dimethyl-oxysilylene];

[0089] L1: 4-(4-[6-(prop-2-enoyloxy)hexyloxy]benzoyloxy)phenyl 4-[6-(prop-2-enoyloxy)hexyloxy]benzoate;

[0090] L2: 3-methyl-4-(4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoyloxy)phenyl 4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoate;

[0091] L3: 5-cyano-2,5-bis(4-{[6-(prop-2-enoyloxy)hexyl]oxy}benzoyloxy)benzoate;

[0092] C1: 4-(4-cyanophenyl)phenyl 4-ethylcyclohexane-1-carboxylate;

[0093] C2: 4-(4-{[(4-ethylcyclohexyl)oxy]carbonyl}phenyl)benzene-1-sulfonic acid;

[0094] C3: 4-[4-(4-methylphenyl)benzoyloxy]benzoic acid.

[0095] Comparative Example 3

[0096] Commercially available liquid crystal depolarizing film (UltraDepol-M, Meadowlark).

[0097] Performance test method

[0098] The depolarizing films in the examples and comparative examples were subjected to performance tests, and the test data are listed in Table 1.

[0099] 1. Use Axoscan to test the phase delay values in Region 1 and Region 2.

[0100] 2. Depolarization Index (DI). The depolarization index is a single parameter used to describe whether the light anywhere in the sample has been depolarized. The depolarization index can range from 0 ≤ DI ≤ 1, where DI = 0 indicates no depolarization and DI = 1 indicates complete depolarization. DI is calculated from the Mueller matrix, and its calculation formula is:

[0101] Use Axoscan to test the depolarization index of the depolarizing film in the range of 400 - 700 nm to obtain DI.

[0102] Among them, " / " was not tested.

[0103] Performance test data

[0104] Table 1

[0105]

[0106]

Claims

1. A depolarization film based on liquid crystal material, characterized in that: The depolarizing film is composed of at least two optically anisotropic regions, including region one and region two; the average inclination angle of the liquid crystal layer in region one relative to the horizontal plane is less than 9°, the optical axis directions of the liquid crystal layers in region one are the same, and the phase delay R0 value of the liquid crystal layer in region one is 200-350nm; the average inclination angle of the liquid crystal layer in region two relative to the horizontal plane is greater than 81°, the optical axis directions of the liquid crystal layers in region two are the same, and the phase delay R0 value of the liquid crystal layer in region two is less than 50nm.

2. The depolarization film based on liquid crystal material according to claim 1, characterized in that: The phase retardation R0 value of the liquid crystal layer in the region 1 is 230-310 nm; the phase retardation R0 value of the liquid crystal layer in the region 2 is <30 nm.

3. The depolarization film based on liquid crystal material according to claim 2, characterized in that: The length and width dimensions of the liquid crystal layer unit in the region 1 are less than 80 μm.

4. The depolarization film based on liquid crystal material according to claim 3, characterized in that: The ratio of the total area of ​​the region 1 to the total area of ​​the region 2 is 0.9-1.

1.

5. The depolarization film based on liquid crystal material according to claim 4, characterized in that: The depolarization film includes an alignment layer and a liquid crystal composition layer.

6. The depolarization film based on liquid crystal material according to claim 5, characterized in that: The photo-alignment material includes poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy-4-[4-[4-[(E)-2-hexyloxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene], poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy- at least one of 6-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-hexyl]-methyl-silylene] and poly[oxy-4-[4-[4-[(E)-2-methoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-oxy-4-4-[4-(E)-2-butoxycarbonyl-vinyl]-phenoxycarbonyl]-phenoxy]-butyl]-methyl-silylene-co-dimethyl-oxy-silylene].

7. The depolarization film based on liquid crystal material according to claim 6, characterized in that: The raw materials for preparing the liquid crystal composition layer include polymerizable liquid crystal, an ester compound containing 4-cyanophenyl group, a photoinitiator and a solvent.

8. A method for preparing a depolarization film based on liquid crystal material according to claim 7, characterized in that: The following steps are involved: S1, coating a photo-alignment material on the surface of a substrate, and obtaining an alignment layer after drying; S2, exposing the alignment layer twice to obtain an alignment layer including region 1 and region 2 respectively; S3, coating a liquid crystal composition layer on the alignment layer including the region 1 and the region 2, and drying and curing.

9. The method for preparing a depolarization film based on liquid crystal material according to claim 8, characterized in that: The energies of the two exposures are E1 and E2 respectively, wherein after the exposure at E1, an alignment layer including region one is obtained, and after the exposure at E2, an alignment layer including region two is obtained.

10. The method for preparing a depolarization film based on liquid crystal material according to claim 9, characterized in that: E1:E2≥3.5, E1≥16.5mJ / cm 2 , preferably greater than E1 ≥ 32 mJ / cm 2 .

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