Liquid crystal type compensation film, preparation method, circular polarizer and display equipment

Abstract

The invention discloses a liquid crystal type compensation film, a preparation method, a circular polarizer and a display device, and by optimizing a liquid crystal material formula, a continuous multi-layer coating process and an LED-UV curing procedure, the stability and optical performance of the compensation film in the environments of high temperature, high temperature and high humidity, low temperature, cold and hot impact and the like are remarkably improved. The preparation method of the compensation film adopts a liquid crystal monomer and photoinitiator composite system; ordered arrangement of liquid crystal molecules is realized by adopting a gradient heating and drying coating process; and in combination with an efficient LED-UV photocuring technology, a high-compactness cross-linked network structure is formed. The obtained compensation film serves as an integrated phase difference film when the compensation film is compounded on a protective film on the upper layer of a polaroid, linearly polarized light emitted by an LCD or OLED display device can be converted into a circular polarization state, so that the display device has a visible function under sunglasses, namely the visible function under the sunglasses, and the service life of the high-end liquid crystal display device is effectively prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of compensation film manufacturing, and in particular to a liquid crystal compensation film, a preparation method, a circular polarizer, and a display device. Background Art

[0002] OLED display technology is widely used in smartphone flat panel displays and outdoor advertising displays. Commonly used OLED circular polarizers consist of a quarter-wave plate and a linear polarizer layer, which can reduce the interference of ambient light on OLED displays. After the picture light emitted by the OLED display panel passes through the outermost polarizer, the picture light will be emitted as linearly polarized light with a specific polarization direction. In daily life and outdoor use scenarios, in order to block light and prevent glare, users will wear polarized sunglasses. When wearing ordinary polarized sunglasses, users will not be able to observe the picture of the OLED display panel at a certain angle, which will cause the user to miss important content on the OLED display panel. The inability to meet the usage requirements of this specific scenario limits the scope and field of use of OLED displays.

[0003] To address this problem, circular polarizers and lens assemblies disclosed in Patent Document 1 CN 209373165 U and Patent Document 2 CN 221303736 U are known. Patent document 1 proposes the following method: the circular polarizer is laminated with inner protective films on both sides of the polarizer, wherein the upper inner protective film has circular polarization properties and can convert the linearly polarized light output by the LCD into a circularly polarized state, so that the LCD has a function of being visible under sunglasses, i.e., a function of being visible under sunglasses (Sunglass Free function). At the same time, the production process is simple and roll-to-roll lamination is possible to achieve high mass production; the LCD display includes the circular polarizer as described above.

[0004] Patent Document 2 proposes a lens assembly comprising a lens and a polarizer with cholesteric liquid crystals. The polarizer with cholesteric liquid crystals is bonded to the lens and is used to convert linearly polarized light into circularly polarized light. The polarizer with cholesteric liquid crystals also blocks light with wavelengths within the polarizer's reflection band. This system can convert linearly polarized light with a specific polarization direction into circularly polarized light with a light vector endpoint trajectories that are circular. Furthermore, circularly polarized light emitted by a display panel with a sunglass-free function can still pass through the polarizer with cholesteric liquid crystals.

[0005] However, the circularly polarizing upper inner protective film employed in the method proposed in Patent Document 1 is made of a QWP material, which exhibits poor optical stability under harsh conditions, i.e., poor reliability. Furthermore, its ellipticity is low in visible light with a wavelength of 400-800nm. In Patent Document 2, users who require OLED and LCD devices that can be viewed at any viewing angle must wear the lens assembly of the invention, which places significant limitations on users and application scenarios. If the lens assembly of the invention is not worn or is damaged, the intended effect of using the OLED and LCD devices cannot be achieved. Summary of the Invention

[0006] The purpose of the embodiments of this specification is to provide a liquid crystal compensation film, a preparation method, a circular polarizer, and a display device to solve the problem of limited application scenarios of lenses in the prior art.

[0007] In order to achieve the above objectives, the embodiments of this specification adopt the following technical solutions: In a first aspect, a method for preparing a liquid crystal compensation film is provided, comprising the following steps: Pre-treating the surface of the film substrate; Coating a photo-alignment material with heat-curing properties on the surface of the pre-treated film substrate, and exposing and curing it to form a photo-alignment layer; A liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer, dried and cured to form a liquid crystal composition layer, thereby obtaining a liquid crystal compensation film.

[0008] Optionally, the film substrate is any one of an optical film and a film substrate with a hard coating; and / or, The thickness of the film substrate is 10 μm-100 μm; and / or, The preset treatment is selected from any one or more combinations of ultraviolet treatment, corona treatment, and plasma treatment.

[0009] Optionally, the photo-alignment material is a photo-alignment material that has been subjected to UV light exposure orientation treatment, the treated UV light is linearly polarized UV light with a wavelength of 300 to 380 nm, and the exposure energy of the exposure is 1 to 500 mJ / cm 2 .

[0010] Optionally, the liquid crystal compound is selected from any one or more combinations of lamellar liquid crystal, linear liquid crystal, cholesteric liquid crystal, and discotic liquid crystal; and / or, The melting temperature of the liquid crystal compound is above 100° C.; and / or, The liquid crystal compound comprises: 20 to 99 parts by weight of a first polymerizable liquid crystal compound and 1 to 80 parts by weight of a second polymerizable liquid crystal compound, wherein the first polymerizable liquid crystal compound is a polymerizable liquid crystal compound having inverse wavelength dispersion, and the second polymerizable liquid crystal compound is a second polymerizable liquid crystal compound having positive wavelength dispersion; and / or, The liquid crystal mixture further comprises a leveling agent, a solvent and a photoinitiator.

[0011] Optionally, the leveling agent is selected from any one or more combinations of silicone leveling agents, polyacrylate compound leveling agents, and fluorine leveling agents; and / or, The solvent is selected from any one or more combinations of toluene, anisole, xylene, cyclohexanone, cyclopentanone, cyclopentanone, N-methylpyrrolidone, ethylene glycol propyl ether, chloroform, and isophorone, which have a boiling point higher than that of the liquid crystal mixture; and / or The photoinitiator is selected from any one or more combinations of cationic photoinitiators, free radical photoinitiators, and water-soluble photoinitiators; and / or, The contents of the components of the liquid crystal mixture are as follows: based on 100 parts by weight, 1 to 25 parts by weight of the liquid crystal compound, 0.01 to 0.1 parts by weight of the leveling agent, 50 to 70 parts by weight of the solvent, and 0 to 5 parts by weight of the photoinitiator.

[0012] Optionally, in the step of applying a liquid crystal mixture containing a liquid crystal compound on the surface of the cured photo-alignment layer, drying and curing to form a liquid crystal composition layer, the curing temperature is 25-100° C. and the curing method is LED-UV light curing; and / or, In the step of applying a liquid crystal mixture containing liquid crystal compounds on the surface of the cured photo-alignment layer, drying and curing to form a liquid crystal composition layer, the drying is gradient drying, and the gradient drying includes a first drying stage, a second drying stage, and a second drying stage. The temperature and time of the first drying stage are less than those of the second drying stage, and the temperature and time of the first drying stage are less than those of the third drying stage. The temperature of the first drying stage is 30~60℃, and the time is 1~30s. The temperature of the second drying stage is 60~80℃, and the time is 1~30s. The temperature of the third drying stage is 80℃, and the time is 30~120s.

[0013] In a second aspect, a liquid crystal compensation film is provided, wherein the liquid crystal compensation film is prepared by the above-mentioned method for preparing the liquid crystal compensation film.

[0014] Optionally, the liquid crystal compensation film is a 1 / 4λ phase difference compensation film, the in-plane phase difference R0 is 100 to 200 nm, and the thickness direction phase difference Rth is 50 to 100 nm.

[0015] In a third aspect, a circular polarizer is provided, comprising the liquid crystal compensation film.

[0016] In a fourth aspect, a display device is provided, comprising the circular polarizer.

[0017] At least one of the above-mentioned technical solutions adopted in the embodiments of the present application can achieve the following beneficial effects: The embodiments of this specification provide a liquid crystal compensation film, a preparation method, a circular polarizer and a display device, adopt photo-alignment technology to align the liquid crystal, adopt a continuous coating manufacturing method, and adopt an LED-UV ultraviolet light curing procedure. Compared with the traditional thermal curing process, the photocuring technology has the advantages of fast speed, low energy consumption, and low solvent formula, which is more in line with the "4E" principle of modern industrial development of economy, efficiency, ecology, and energy. It not only simplifies the preparation process of the compensation film and effectively improves production efficiency, but also the obtained compensation film has excellent optical performance when applied to OLED display devices, and has the function of being visible under sunglasses (Sunglass Free function), and exhibits excellent optical stability in various usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a structural schematic diagram of a liquid crystal compensation film provided by the present invention.

[0019] Figure 2 It is a schematic structural diagram of another liquid crystal compensation film provided by the present invention. Figure 3 It is a structural schematic diagram and optical path schematic diagram of the circular polarizer provided by the present invention. Figure 4 This is a schematic diagram of an OLED display device with SGF function and a light path provided by the present invention.

[0020] Description of reference numerals: 100 - liquid crystal compensation film, 200 - liquid crystal compensation film with hard coating, 300 - circular polarizer; 101 - film substrate; 102 - photo-alignment layer; 103 - liquid crystal composition layer; 201-hard coating; 202-film substrate; 203-photoalignment layer; 204-photoalignment layer; 300-circular polarizer; 301-liquid crystal compensation film layer; 302-adhesive layer; 303-polarizer layer; 304-polarizer protective film; 400-Organic electroluminescent display device and optical path with SGF function; 401-OLED organic light-emitting device; 402-Circular polarizer; 403-Linear polarizer; 404-Circular polarizer; 405-Sunglasses; 406-Human eye. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] The present invention provides a method for preparing a liquid crystal compensation film, comprising the following steps: Pre-treating the surface of the film substrate; Coating a photo-alignment material with heat-curing properties on the surface of the pre-treated film substrate, and exposing and curing it to form a photo-alignment layer; A liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer, dried and cured to form a liquid crystal composition layer, thereby obtaining a liquid crystal compensation film.

[0023] In the embodiments of this specification, the film substrate is any one of an optical film and a film substrate with a hard coating. The optical film is selected from any one of polyethylene film, polypropylene film, polyvinyl chloride film, polyester film, cellulose film, polyolefin film, and polyester film. A hard coating is referred to as a hard coating. The film substrate has a thickness of 10 μm to 100 μm. Depending on the requirements of OLED displays, the film substrate may preferably be triacetyl cellulose (TAC) film.

[0024] In the embodiments of this specification, the preset treatment is selected from any one or more combinations of ultraviolet treatment, corona treatment, and plasma treatment.

[0025] In the examples of this specification, the coating is uniform.

[0026] In the embodiment of this specification, the photo-aligned material is a photo-aligned material that has been subjected to UV light exposure orientation treatment, the treated UV light is linearly polarized UV light with a wavelength of 300 to 380 nm, and the exposure energy of the exposure is 1 to 500 mJ / cm 2 .

[0027] In the embodiments of this specification, a liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer, and in the step of drying and curing to form a liquid crystal composition layer, the curing temperature is 25~100°C, and the curing method is LED-UV light curing.

[0028] In the embodiments of this specification, in the step of applying a liquid crystal mixture containing liquid crystal compounds to the surface of the cured photo-alignment layer, drying and curing to form a liquid crystal composition layer, the drying is performed using a gradient drying method. The gradient drying method is divided into three stages: the temperature of the first drying stage, the temperature of the second drying stage, and the temperature of the third drying stage. The first drying stage has the lowest temperature and the shortest drying time; the second drying stage should have a lower temperature than the third drying stage and a shorter drying time than the third drying time; the third drying stage is the primary drying stage, determined based on the clearing point temperature and glass transition temperature (Tg) of the selected liquid crystal, with the highest drying temperature and the longest drying time. Specifically, the first drying stage has the lowest temperature (30-60°C) and the shortest drying time (1-30 seconds); the second drying stage should have a lower temperature than the third drying stage (60-80°C) and a drying time of 1-30 seconds; and the third drying stage is the primary drying stage, determined based on the clearing point temperature and glass transition temperature (Tg) of the selected liquid crystal, with the highest drying temperature (80°C) and the longest drying time (30-120 seconds).

[0029] In the embodiments of this specification, the liquid crystal compound is selected from any one or more combinations of lamellar liquid crystals, linear liquid crystals, cholesteric liquid crystals, and discotic liquid crystals. Based on the requirements of OLED display devices, the liquid crystal compound is preferably a liquid crystal compound with good thermal stability. The melting temperature of the liquid crystal compound is above 100°C. The liquid crystal compound comprises: 20 to 99 parts by weight of a first polymerizable liquid crystal compound and 1 to 80 parts by weight of a second polymerizable liquid crystal compound. The first polymerizable liquid crystal compound has inverse wavelength dispersion, and the second polymerizable liquid crystal compound has positive wavelength dispersion. When the liquid crystal compensation film prepared using this example is applied to the SGF mode, the ellipticity at wavelengths between 400 and 800 nm is close to 1. The ellipticity represents the linear-to-circular conversion efficiency. The closer the ellipticity is to 1, the higher the conversion efficiency and the higher the brightness observed in the SGF mode.

[0030] The first polymerizable liquid crystal compound and the second polymerizable liquid crystal compound are also selected from any one of lamellar liquid crystal, linear liquid crystal, cholesteric liquid crystal, and discotic liquid crystal. Specifically, the first polymerizable liquid crystal compound A1 and the second polymerizable liquid crystal compound A2 have the following corresponding structures:

[0031] In the embodiments of this specification, the liquid crystal mixture further includes a leveling agent, a solvent, and a photoinitiator. The leveling agent is selected from any one or more of a silicone leveling agent, a polyacrylate leveling agent, and a fluorine leveling agent. Preferably, the leveling agent is selected from a leveling agent that has good compatibility with the liquid crystal compound. Specifically, the silicone leveling agent can be any one or more of MONENG-1071, synde-123, synde-122D, BYK-306, BYK-300, BYK-330, BYK-310, DC-433, DC-431, KEPERSURF-150, DC57, JN-456, JS-3000; the polyacrylate leveling agent can be any one or more of MONENG-1152, JU-3777, Flomax 6010, MOK-2623, WE-D811, Sjoy-6358, BYK-354, BYK-352, BYK-357; the fluorine leveling agent can be EFKA-3600, LD-91084 / LD-91085, Hyperlev F20, Hydropalat WE Any one or more combinations of 3229, Hyperlev F81, and Sago-3800.

[0032] The solvent is selected from any one or more combinations of toluene, anisole, xylene, cyclohexanone, cyclopentanone, cyclopentanone, N-methylpyrrolidone, ethylene glycol propyl ether, chloroform, and isophorone, with a boiling point higher than the boiling point of the liquid crystal mixture. Preferably, the solvent is a solvent mixture having good solubility for the liquid crystal compound and moderate volatility to prevent precipitation of the liquid crystal compound.

[0033] The photoinitiator is selected from any one or more combinations of cationic photoinitiators, free radical photoinitiators, and water-soluble photoinitiators. Among them, free radical photoinitiators can be divided into two types: cleavage photoinitiators and hydrogen abstraction photoinitiators. The cleavage photoinitiator can be selected from any one or more combinations of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L), oxime ester O-Benzoyl-α-oxooxime (OXE-01), oxime ester O-acetyloxime (OXE-02), BASF brand OXE-03, OXE-04, and OXE-05. The hydrogen abstraction photoinitiator can be selected from any one or more combinations of benzophenones (BP), thioxanthones (TX), and camphorquinones (CQ). The water-soluble photoinitiator can be selected from any one or more combinations of Irgacure 2959, Irgacure 184, Irgacure 369, Irgacure 651, and Irgacure 907. When the curing method is LED-UV light curing, the photoinitiator is preferably selected from any one or more combinations of free radical photoinitiators such as cleavage-type free radical photoinitiators and hydrogen abstraction-type photoinitiators. Photoinitiators suitable for use in the present invention may include, but are not limited to, the compounds described in the structures of Formulas M-1 to M-7 below.

[0034]

[0035] The liquid crystal mixture may further include any one or more combinations of a catalyst, an antioxidant, an ultraviolet absorber, an antistatic agent, a dispersion stabilizer, a defoamer, a thickener, a dispersant, a surfactant, a lubricant, and a silane coupling agent as additives as needed. The contents of the components of the liquid crystal mixture are as follows: per 100 parts by weight, 1 to 25 parts by weight of the liquid crystal compound, 0.01 to 0.1 parts by weight of a leveling agent, 50 to 70 parts by weight of a solvent, and 0 to 5 parts by weight of a photoinitiator.

[0036] In a second aspect, a liquid crystal compensation film is provided, wherein the liquid crystal compensation film is prepared by the above-mentioned method for preparing the liquid crystal compensation film.

[0037] In the embodiment of this specification, the liquid crystal compensation film is a 1 / 4λ phase difference compensation film, the in-plane phase difference R0 is 100-200 nm, and the thickness direction phase difference Rth is 50-100 nm.

[0038] In the embodiments of this specification, the liquid crystal compensation film can be adapted to the Roll to Roll process.

[0039] In a third aspect, a circular polarizer is provided, comprising the liquid crystal compensation film.

[0040] In the embodiment of this specification, the circular polarizer includes a liquid crystal compensation film layer, a polarizer layer, and an adhesive layer.

[0041] In a fourth aspect, a display device is provided, comprising the circular polarizer.

[0042] In the embodiment of this specification, the circular polarizer is an organic electroluminescent display device with SGF function.

[0043] The following describes in detail the technical solutions provided by various embodiments of the present application in conjunction with the accompanying drawings.

[0044] In the following examples, all raw materials used were commercially available unless otherwise specified. A first polymerizable liquid crystal compound A1 and a second polymerizable liquid crystal compound A2 were used, with the structures of A1 and A2 shown above. The leveling agent and solvent used in all examples were of the same type and quality, with BYK-354 being the leveling agent. The solvent was a mixture of toluene and cyclohexanone, so unless otherwise specified in the examples, "B" is used to represent the solvent.

[0045] The in-plane phase difference R0 and thickness direction phase difference Rth were tested using Axoscan equipment at 25±2°C. The transmittance and haze of the compensation film were tested using NDH-8000 haze meter equipment according to JIS K7105-81 standard at 25±2°C. The reliability test was conducted using a constant temperature and humidity chamber. The test conditions include: High temperature: 85℃ 500H; Thermal shock: -40℃ (30min) ~ 85℃ (30min), 100cyc; High temperature and high humidity: 60℃ / 90%RH500H; Low temperature: -40℃500H.

[0046] Examples 1-17 and Comparative Examples 1-6 A method for preparing a liquid crystal compensation film is provided, comprising the following steps: (1) A liquid crystal composition was prepared by mixing 75 parts of A1 and 25 parts of A2. The photoinitiators were added to the liquid crystal composition according to Table 1 below. The same B was also added to the composition. The mixture was stirred and dissolved to prepare a liquid crystal mixture.

[0047] (2) Pre-treating the surface of the TAC film substrate.

[0048] (3) A photo-alignment material with heat-curing properties is uniformly coated on the surface of the TAC film substrate after the preset treatment, and then exposed and cured to form a photo-alignment layer.

[0049] (4) A liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer and dried in an oven according to the gradient drying method of each embodiment in Table 1 below to obtain an uncured liquid crystal composition layer. The temperature of the first drying stage is the lowest (30-60°C) and the drying time is the shortest (1-30 seconds). The second drying temperature should be lower than the temperature of the third drying stage (60-80°C) and the drying time is 1-30 seconds. The third drying temperature is the main drying temperature, which is determined based on the clearing point temperature and glass transition temperature (Tg) of the selected liquid crystal, and the drying temperature is the highest (80°C) and the drying time is the longest (30-120 seconds).

[0050] (5) The liquid crystal composition layer obtained in step (4) was cured according to the UV curing energy of each example and comparative example in Table 1 below.

[0051] The structure of the liquid crystal compensation film is shown in Figure 1 The liquid crystal compensation film 100 includes a film substrate 101 and a photo-alignment layer 102 and a liquid crystal composition layer 103 disposed on the film substrate 101. Table 1 shows the R0 change after 500 hours of reliability testing at 85°C for Examples 1-17 and Comparative Examples 1-6.

[0052] Table 1

[0053] The test results of Examples 1-9 in Table 1 show that the optical stability of the compensation films produced using the same liquid crystal composition with different photoinitiators, using the same preparation process, varies. Photoinitiator M-1 used in Example 1 produces the most stable optical film. The photoinitiator is the most critical component of the entire photocuring system, directly determining the curing speed and effectiveness of the entire system, and ultimately, the stability of the compensation film's optical properties. Comparative Examples 1-6 show that, after the liquid crystal compensation film formulation of Example 1 undergoes a 500-hour curing treatment at 85°C, the change in its key optical parameter, in-plane retardation (R0), decreases as the UV curing energy increases to above 1600 mJ. The change in R0 is less than 10 nm, indicating a more stable compensation film.

[0054] The test results of Examples 1 and 10-17 demonstrate that, with the same liquid crystal mixture formulation, adjusting the gradient drying process can further enhance the stability of the compensation film's optical properties. Specifically, Example 17 achieved an R0 change of less than 5 nm after 500 hours of reliability testing at 85°C. Because liquid crystal compensation films deteriorate more significantly at 85°C, Example 17 was tested under other reliability conditions. The test results are shown in Table 3.

[0055] Examples 18-22 and Comparative Examples 7-12 A method for preparing a liquid crystal compensation film is provided, comprising the following steps: (1) 85 parts of A1 and 15 parts of A2 constitute a liquid crystal composition. The photoinitiators are added to the liquid crystal composition according to Table 2 below. The same B is also added to the composition. The mixture is stirred and dissolved to prepare a liquid crystal mixture.

[0056] (2) Pre-treating the surface of the TAC film substrate.

[0057] (3) A photo-alignment material with heat-curing properties is uniformly coated on the surface of the TAC film substrate after the preset treatment, and then exposed and cured to form a photo-alignment layer.

[0058] (4) A liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer, and dried in an oven according to the gradient of each embodiment in Table 1 below to obtain an uncured liquid crystal composition layer.

[0059] (5) The liquid crystal composition layer obtained in step (4) was cured according to the UV curing energy of each example and comparative example in Table 2 below.

[0060] Table 2 shows the R0 change after 500 hours of reliability test at 85℃ for Examples 18-22 and Comparative Examples 7-12. Table 2

[0061] Table 2 shows that in a liquid crystal composition of 85 parts A1 and 15 parts A2 using the M-2 photoinitiator, the compensation film undergoes a 500-hour deterioration treatment at 85°C. The change in its main optical parameter, in-plane retardation R0, decreases with increasing UV curing energy, and the optical properties of the compensation film become more stable.

[0062] It's worth noting that different formulations don't simply increase the UV curing energy to produce a more stable compensation film. Comparative Example 7 shows that, in the formulation of Example 11, increasing the UV curing energy to 2000 mJ doesn't reduce the change in R0. Therefore, different formulations require the use of a correspondingly matched UV curing energy.

[0063] Table 3 shows the changes in transmittance, haze, and R0 under various reliability conditions of Example 17.

[0064] Table 3

[0065] The results in Table 3 show that in Example 17, under all OLED application scenarios, the change in R0 is less than 3 nm, the transmittance is greater than 90%, and the haze is less than 1%, which meets the requirements of the usage scenarios.

[0066] The above Examples 1-22 and Comparative Examples 1-12 are merely some examples listed in this application. For those skilled in the art, various modifications and variations are possible in this application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0067] Example 23 Similarly, the present invention provides a method for preparing a liquid crystal compensation film with a hard coating. The liquid crystal compensation film with a hard coating comprises a film substrate 202 with a hard coating 201, a photo-alignment layer 203 disposed on the film substrate, and a liquid crystal composition layer 204 coated on the surface of the photo-alignment layer. The preparation method is consistent with the steps in Example 1 and will not be described in detail. The structure of the prepared liquid crystal compensation film is shown in FIG. Figure 2 .

[0068] Example 24 The present invention provides a circular polarizer 300, such as Figure 3 As shown, the circular polarizer includes the aforementioned liquid crystal compensation film layer 301 with a 1 / 4λ phase difference, a polarizer layer 303, an adhesive layer 302, and a polarizer protective film 304. The polarizer layer is a polyvinyl alcohol film (PVA), the polarizer protective film is a triacetyl cellulose film (TAC), and the adhesive layer is made of polyvinyl alcohol adhesive or UV adhesive.

[0069] The optical axis of the liquid crystal compensation film layer 301 with a preferred 1 / 4λ phase difference is consistent with the optical axis of the polarizer layer 303. When the incident light enters the polarizer layer 303 from the polarizer protective film 304, it becomes linearly polarized light perpendicular to the absorption axis of the polarizer layer 303. When it passes through the liquid crystal compensation film layer 301 with a 1 / 4λ phase difference, the linearly polarized light becomes circularly polarized light with uniform brightness at all angles.

[0070] The circular polarizer 300 is an integrated phase difference film that can be applied to phase difference films such as conventional OLED anti-reflection circular polarizers. The scope of use is not limited to SGF and can also be used in other directions. Example 25 The present invention provides an organic electroluminescent display device with SGF function, including an OLED organic light emitting device 401, a circular polarizer 402, a linear polarizer 403, and a circular polarizer 404. The specific structure and the light path of the light source are as follows: Figure 4 shown.

[0071] The OLED organic light-emitting device can emit natural light; the circular polarizer 402 is a 1 / 4λ phase difference film, preferably a QWP material and a liquid crystal compensation film material; the linear polarizer 403 is composed of an upper protective film, a polarizer layer, and a lower protective film, and can convert the natural light emitted by the OLED organic light-emitting device into linearly polarized light consistent with the optical axis of the polarizer; the circular polarizer 404 is the circular polarizer structure provided in Example 24, and can convert the linear polarized light passing through the linear polarizer 403 into circularly polarized light close to natural light.

[0072] Furthermore, the sunglasses worn daily by users of OLED display devices are all linearly polarized light. The circularly polarized light that has passed through 404 can pass through the sunglasses at any angle and be recognized by the human eye. It has the full-angle visibility function under any sunglasses, that is, the visibility function under sunglasses (Sunglass Free function).

[0073] The preparation method of the present invention is adaptable to continuous coating using roll-to-roll equipment, enabling high-efficiency continuous production, improved scale efficiency, and good cost-effectiveness. It possesses extremely high flexibility, adaptability, and technical scalability. The resulting compensation film exhibits excellent optical performance and stable performance, exhibiting outstanding optical stability in high-temperature, high-temperature and high-humidity, low-temperature, and thermal shock environments. The in-plane phase difference (R0) variation within 500 hours is less than 3 nm, the transmittance is greater than 90%, and the haze is less than 1%. When applied to LCD-IPS and OLED display devices, the service life of the display device can be effectively increased. When used as the upper protective film for a polarizer, the compensation film provided by the present invention can convert linearly polarized light emitted by an OLED into a circularly polarized state, enabling full-angle viewing under any pair of sunglasses, i.e., a sunglass-free function.

[0074] The present invention significantly improves the stability and optical performance of the compensation film in environments such as high temperature, high temperature and high humidity, low temperature, and thermal shock by optimizing the liquid crystal material formula, continuous multi-layer coating process, and LED-UV curing procedure. The preparation method of the compensation film adopts a composite system of liquid crystal monomers and photoinitiators; a gradient temperature rising and drying coating process is used to achieve the orderly arrangement of liquid crystal molecules; and a highly dense cross-linked network structure is formed by combining with efficient LED-UV light curing technology. The obtained compensation film, when compounded with the upper protective film of the polarizer, serves as an integrated phase difference film. It can convert linearly polarized light emitted by LCD or OLED display devices into a circularly polarized state, enabling it to be visible under sunglasses, i.e., a sunglass-free function, effectively extending the service life of high-end liquid crystal display devices. The present invention achieves a highly environmentally reliable compensation film technology through material formula optimization and process adjustment, and is suitable for harsh working conditions such as mobile phone displays, vehicle displays, and outdoor display screens.

[0075] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for preparing a liquid crystal compensation film, characterized in that: The following steps are involved: Pre-treating the surface of the film substrate; Coating a photo-alignment material with heat-curing properties on the surface of the pre-treated film substrate, and exposing and curing it to form a photo-alignment layer; A liquid crystal mixture containing liquid crystal compounds is coated on the surface of the cured photo-alignment layer, dried and cured to form a liquid crystal composition layer, thereby obtaining a liquid crystal compensation film.

2. The preparation method according to claim 1, characterized in that The film substrate is any one of an optical film and a film substrate with a hard coating; and / or, The thickness of the film substrate is 10 μm-100 μm; and / or, The preset treatment is selected from any one or more combinations of ultraviolet treatment, corona treatment, and plasma treatment.

3. The preparation method according to claim 1, characterized in that The photo-alignment material is a photo-alignment material that has been subjected to UV light exposure and orientation treatment, wherein the treated UV light is linearly polarized UV light with a wavelength of 300 to 380 nm, and the exposure energy of the exposure is 1 to 500 mJ / cm 2 .

4. The preparation method according to claim 1, characterized in that The liquid crystal compound is selected from any one or more combinations of lamellar liquid crystal, linear liquid crystal, cholesteric liquid crystal, and discotic liquid crystal; and / or, The melting temperature of the liquid crystal compound is above 100° C.; and / or, The liquid crystal compound comprises: 20 to 99 parts by weight of a first polymerizable liquid crystal compound and 1 to 80 parts by weight of a second polymerizable liquid crystal compound, wherein the first polymerizable liquid crystal compound is a polymerizable liquid crystal compound having inverse wavelength dispersion, and the second polymerizable liquid crystal compound is a second polymerizable liquid crystal compound having positive wavelength dispersion; and / or, The liquid crystal mixture further comprises a leveling agent, a solvent and a photoinitiator.

5. The preparation method according to claim 4, characterized in that The leveling agent is selected from any one or more combinations of silicone leveling agents, polyacrylate leveling agents, and fluorine leveling agents; and / or, The solvent is selected from any one or more combinations of toluene, anisole, xylene, cyclohexanone, cyclopentanone, cyclopentanone, N-methylpyrrolidone, ethylene glycol propyl ether, chloroform, and isophorone, which have a boiling point higher than that of the liquid crystal mixture; and / or The photoinitiator is selected from any one or more combinations of cationic photoinitiators, free radical photoinitiators, and water-soluble photoinitiators; and / or, The contents of the components of the liquid crystal mixture are as follows: based on 100 parts by weight, 1 to 25 parts by weight of the liquid crystal compound, 0.01 to 0.1 parts by weight of the leveling agent, 50 to 70 parts by weight of the solvent, and 0 to 5 parts by weight of the photoinitiator.

6. The preparation method according to claim 1, characterized in that In the step of applying a liquid crystal mixture containing a liquid crystal compound on the surface of the cured photo-alignment layer, drying and curing to form a liquid crystal composition layer, the curing temperature is 25-100° C., and the curing method is LED-UV light curing; and / or, In the step of applying a liquid crystal mixture containing liquid crystal compounds on the surface of the cured photo-alignment layer, drying and curing to form a liquid crystal composition layer, the drying is gradient drying, and the gradient drying includes a first drying stage, a second drying stage, and a second drying stage. The temperature and time of the first drying stage are less than those of the second drying stage, and the temperature and time of the first drying stage are less than those of the third drying stage. The temperature of the first drying stage is 30~60℃, and the time is 1~30s. The temperature of the second drying stage is 60~80℃, and the time is 1~30s. The temperature of the third drying stage is 80℃, and the time is 30~120s.

7. A liquid crystal compensation film, characterized in that: The liquid crystal compensation film is prepared by the preparation method of the liquid crystal compensation film according to any one of claims 1 to 6.

8. The liquid crystal compensation film according to claim 7, characterized in that: The liquid crystal compensation film is a 1 / 4λ phase difference compensation film, the in-plane phase difference R0 is 100-200 nm, and the thickness direction phase difference Rth is 50-100 nm.

9. A circular polarizer, characterized in that: The circular polarizer includes the liquid crystal compensation film according to claim 7 or 8.

10. A display device, characterized in that: The display device comprises the circular polarizer according to claim 9.

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