Ultrathin dye polarizer, preparation method and ultrathin circular polarizer

Abstract

The invention relates to an ultra-thin dye polaroid, a preparation method and an ultra-thin circular polaroid, and the ultra-thin dye polaroid comprises polyethylene glycol terephthalate-1, 4-cyclohexanedimethanol and a dye dispersed in the polyethylene glycol terephthalate-1, 4-cyclohexanedimethanol in a dissolving mode. According to the invention, dye is dissolved and dispersed in polyethylene glycol terephthalate-1, 4-cyclohexanedimethanol, and the ultrathin dye polaroid is finally obtained through the steps of mixing, extrusion, coating, curtain coating, one-way calendering, stretching and drying. On one hand, a dissolving and dispersing mode is adopted, dye dispersion is more uniform, and the polarization degree and the light transmittance of all parts of the polaroid are guaranteed; on the second aspect, the polaroid does not need to be clamped and fixed by a cellulose triacetate film, so that the thickness of the polaroid can be further reduced; and thirdly, the retarder is compounded on the ultrathin dye polaroid, so that the purpose of manufacturing the ultrathin circular polaroid is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical functional film, in particular to an ultrathin dye polarizer, a preparation method and an ultrathin circular polarizer. BACKGROUND

[0002] At present, the main products of display devices are TFT-LCD and OLED, and these displays all need to use an optical functional film, i.e. a polarizer. With the development of display technology, the development of flexible display devices has become one of the future development directions, so the development of ultrathin polarizers or ultrathin circular polarizers has become the most advanced and difficult hot project in the polarizer manufacturing industry. In recent years, a large number of patents for manufacturing ultrathin polarizers have appeared, but no products have been formed, which shows the great difficulty.

[0003] The existing typical industrialized absorption-type polarizer is composed of two pieces of tri-acetyl cellulose (TAC) film and a piece of polyvinyl alcohol (PVA) polarizer element film. The polarizer element film can be a PVA film impregnated with iodine or a PVA film impregnated with dichroic dye and then stretched to form a polarizer functional film layer. When natural light is incident, polarized light along the stretching direction is absorbed, and polarized light along the vertical stretching direction is not absorbed and transmits. Since the PVA film will shrink and deform, TAC film must be used to prevent shrinkage and deformation. The single PVA film or TAC film cannot be made too thin, so the sandwich structure causes the existing polarizer to be relatively thick, which is not suitable for application in flexible displays. In the general structure of the polarizer product, the typical thickness of the PVA film layer is 25 μm, and the thickness of the TAC film is also 25 μm, so the typical effective thickness of the TAC-PVA-TAC structure polarizer is 75 μm. In addition, the typical thickness of the disc-shaped liquid crystal retardation film (wave plate) used in the circular polarizer is 2 μm, the thickness of the PET release film is 50 μm, and the thickness of the PE protective film is 30 μm. In addition, there are composite glue and pressure sensitive adhesive between the films, and the cumulative thickness of these glue layers is nearly 30 μm. It can be seen that the actual thickness of the polarizer product before being attached to the display device is more than 100 μm. The above problems need to be solved. SUMMARY

[0004] The present application discloses an ultrathin dye polarizer, a preparation method and an ultrathin circular polarizer, and aims to solve the technical problems in the prior art.

[0005] The present application adopts the following technical scheme: In a first aspect, the present application provides an ultrathin dye polarizer, which comprises polyethylene terephthalate-1,4-cyclohexane dimethanol (PETG) and dichroic dye dispersed in the PETG by a dissolution method.

[0006] In a second aspect, the present application also provides a preparation method of the above-mentioned ultra-thin dye polarizer, sequentially comprising the following steps: mixing, extruding, coating, casting, unidirectional calendering, stretching and drying.

[0007] In the preparation method of the ultra-thin dye polarizer, the mixing step comprises: dissolving a dye in a first solvent to obtain a first mixed solution; dissolving polyethylene terephthalate-1,4-cyclohexane dimethanol in a second solvent to obtain a second mixed solution, the second solvent and the first solvent being miscible; mixing the first mixed solution and the second mixed solution uniformly to obtain a third mixed solution, and the mixing is completed.

[0008] In the preparation method of the ultra-thin dye polarizer, the first solvent is propylene glycol methyl ether acetate; and the second solvent is dichloromethane.

[0009] In the preparation method of the ultra-thin dye polarizer, the mass percentage content of the dye in the first mixed solution is 1%-10%; and the mass percentage content of the PETG in the second mixed solution is 15%-35%.

[0010] In the preparation method of the ultra-thin dye polarizer, the mass percentage content of the dye in the polarizer is 0.5%-5%.

[0011] In the preparation method of the ultra-thin dye polarizer, the temperature of the casting machine in the casting step is 80℃-88℃.

[0012] In the preparation method of the ultra-thin dye polarizer, the extrusion port slit gap of the coating machine in the extruding and coating step is 60μm-120μm.

[0013] In the preparation method of the ultra-thin dye polarizer, a multi-stage calendering machine is used in the unidirectional calendering and stretching step; the distance between the calendering rollers of the multi-stage calendering machine decreases in turn along the conveying direction, the linear speed increases in turn, and the multi-stage calendering machine is a heated calendering machine, and the heating temperature is 80℃-88℃.

[0014] In the preparation method of the ultra-thin dye polarizer, the drying step is carried out in a tunnel type drying oven, and the drying temperature is lower than the softening temperature of the PETG.

[0015] In the preparation method of the ultra-thin dye polarizer, a compounding step is further included. The compounding step comprises: A protective film is adhered to one side of the polarizing sheet, and a release film is adhered to the other side of the polarizing sheet.

[0016] In a third aspect, the present application also provides an ultrathin circular polarizing sheet, comprising the polarizing sheet described above or the polarizing sheet prepared by any of the preparation methods described above and a retardation plate.

[0017] The technical scheme adopted by the present application can achieve the following beneficial effects: The present application mainly provides an ultrathin dye polarizing sheet. Based on dissolving and dispersing dyes in polyethylene terephthalate-1,4-cyclohexane dimethanol, in a first aspect, the dyes are dispersed more uniformly in a dissolved and dispersed manner, so that the uniformity of the polarization degree and the transmittance of each part of the polarizing sheet is guaranteed; in a second aspect, the polarizing sheet of the present application does not need to be clamped and fixed by triacetate cellulose (TAC) film, and the thickness of the polarizing sheet can be further reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows, which form a part of the present application. The illustrative embodiments of the present application and their description and explanation do not constitute an improper limitation on the present application. In the drawings: Figure 1 The structure schematic diagram of the polarizing sheet of the present application before calendering and stretching; Figure 2 The structure schematic diagram of the polarizing sheet of the present application after calendering and stretching; Figure 3 The structure schematic diagram of the ultrathin polarizing sheet processing system of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme of the present application will be described clearly and completely in combination with the specific embodiments of the present application and the corresponding drawings. In the description of the present application, it needs to be explained that the term “or” is generally used in the meaning of including “and / or”, unless the content is explicitly indicated otherwise.

[0020] Unless explicitly indicated as the opposite meaning, the numerical parameters in the specification and the attached claims can be approximate values, which can be changed according to the required characteristics obtained by the content of the present application. Specifically, all the numbers used in the specification and the claims to express the content of the composition, reaction conditions, etc. should be understood as being modified by the term “about” in all cases. Generally, it means that the expression includes a change of ±10% in some embodiments, a change of ±5% in some embodiments, a change of ±1% in some embodiments, and a change of ±0.5% in some embodiments.

[0021] Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "comprising" encompasses the notions of "consisting of", "consisting essentially of", and "substantially consisting of". The use of the word "about" in relation to a numerical value means ±10% of the value.

[0022] In addition, unless particularly described or steps must occur in sequence, the order of the steps described above is not limited to the above list, and can be changed or rearranged according to the desired design. Moreover, the above embodiments can be mixed and used with each other or with other embodiments based on design and reliability considerations, that is, technical features in different embodiments can be freely combined to form more embodiments.

[0023] Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0024] To solve the problems in the prior art, the embodiments of the present application provide an ultrathin dye polarizing sheet, a preparation method and a circular polarizing sheet.

[0025] An ultrathin dye polarizing sheet, the polarizing sheet comprising polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate (PETG) and dichroic dye (such as liquid crystal dye) uniformly oriented by being dispersed in the polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate by a dissolution method, such as Figure 2 That is, a dye-doped polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate (PETG) film.

[0026] The present application mainly provides an ultrathin dye polarizing sheet, based on dissolving and dispersing dye in polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate, in a first aspect, adopting a dissolving and dispersing method, the dye is more uniformly dispersed, so that the polarization degree and the transmittance of each part of the polarizing sheet are guaranteed; in a second aspect, the polarizing sheet of the present application does not need to be clamped and fixed with triacetate cellulose (TAC) film, and can further reduce the thickness of the polarizing sheet, which can be below 40 μm, even below 10 μm, and is suitable for preparing flexible displays and circular polarizing sheets.

[0027] In some preferred embodiments, the dye is a dichroic dye that is a lipid-soluble dye that can be dissolved and dispersed in PETG, that is, a liquid crystal dye for guest-host effect liquid crystal display.

[0028] In some preferred embodiments, the polarizing sheet further comprises a release film disposed on one side and a protective film disposed on the other side.

[0029] In some preferred embodiments, the thickness of the polarizing sheet is 10-40 μm; avoiding too low thickness causing processing difficulty, and too high thickness affecting subsequent use experience, such as affecting softness causing processing difficulty when processing flexible display screen.

[0030] In some preferred embodiments, the mass percentage content of the dye in the polarizing sheet is 0.5%-5%; within this range, the degree of polarization and the light transmittance of the polarizing sheet are ensured to be within a suitable range.

[0031] A preparation method of the above-mentioned ultra-thin dye polarizing sheet, sequentially comprising the following steps: Mixing, extrusion, coating, casting, unidirectional calendering, stretching and drying.

[0032] In some preferred embodiments, the mixing step comprises: dissolving the dye in a first solvent to obtain a first mixed solution; dissolving polyethylene terephthalate-1,4-cyclohexane dimethanol in a second solvent to obtain a second mixed solution, the second solvent and the first solvent being miscible; mixing the first mixed solution and the second mixed solution uniformly to obtain a third mixed solution, and the mixing is completed.

[0033] Preferably, the mixing process is carried out in a vacuum stirred tank, and the subsequent steps are carried out after the mixed solution is defoamed. Alternatively, the mixing time in the vacuum stirred tank is 12-36 h, and then the stirring is stopped and the defoaming time is 12-36 h, or it is determined according to the actual working condition.

[0034] Preferably, the first solvent is propylene glycol methyl ether acetate; and the second solvent is dichloromethane.

[0035] Preferably, the mass percentage content of the dye in the first mixed solution is 1%-10%; and the mass percentage content of PETG in the second mixed solution is 15%-35%; based on this, the dissolution of the dye and PETG is more sufficient, and the concentration of each part in the third mixed solution formed is more uniform; too low content causes too long processing time in the subsequent solvent evaporation process, and too high content affects the uniformity of mixing and increases the operation difficulty in the extrusion process. In specific operation, the addition amount of the first mixed solution and the second mixed solution is 5%-15% and 85%-95% of the third mixed solution respectively, or other ratios, which are determined according to the working condition.

[0036] In some preferred embodiments, the temperature of the casting machine in the casting step is 80°C-88°C; based on this, PETG is heated to its glass transition temperature, and the solvent is evaporated, improving the stretchability and compressibility of the cast film; preferably, the casting step ends when the cast film can be completely lifted.

[0037] Preferably, the casting machine can be either a stainless steel rotary casting machine or a stainless steel conveyor belt casting machine.

[0038] In some preferred embodiments, the slit gap of the extrusion nozzle of the coating machine in the extrusion and coating steps is 60μm-120μm, that is, the thickness of the cast film is 60μm-120μm. Figure 1 As shown in the figure, 1-1 represents a relatively thick soft film cast by PETG extrusion coating; 1-2 represents randomly oriented liquid crystal dye molecules dissolved and dispersed in the thick PETG film. Within this range, the stability of the cast film thickness can be improved. Preferably, the slit gap of the extrusion nozzle of the coating machine is 75-80 μm.

[0039] In some preferred embodiments, a multi-stage calender is used in the unidirectional calendering and stretching steps; the spacing between the calendering rollers of the multi-stage calender decreases sequentially along the conveying direction, and the linear speed increases sequentially; the multi-stage calender is a heated calender with a heating temperature of 80℃-88℃; by heating and calendering, the calendered film is simultaneously subjected to appropriate unidirectional straightening, and the film is slightly narrowed and stretched to obtain a unidirectional calendered and stretched soft film of PETG containing a small amount of solvent and dye; after unidirectional stretching, a softer film with a narrower width is obtained, such as... Figure 2 As shown in the figure, 2-1 is a unidirectional calendered ultrathin hard film of PETG; 2-2 is liquid crystal dye molecules dissolved and dispersed in the PETG film with uniform orientation; improving the stretchability of the film during the calendering process, thereby increasing the stretch ratio, for example, a stretch ratio of 6-7, can improve the orderliness of the dye arrangement; and based on the use of heating calendering at 80℃-88℃, the solvent can be further evaporated, improving the shape retention of the film during the calendering process, thereby ensuring the orientation consistency and product specifications of the polarizer.

[0040] Preferably, the thickness of the calendered film is 20-40 μm.

[0041] Preferably, the calendering step uses a multi-stage calender, and the spacing of the calendering rolls of the multi-stage calender decreases sequentially along the conveying direction; such as 60μm, 40μm, 20μm, etc., which are determined according to the requirements.

[0042] Preferably, the content of the second solvent in the polarizer output from the calender is greater than 0 and less than or equal to 10%; thereby, the stretchability of the cast film can be further improved without affecting the polarization degree and transmittance of the polarizer.

[0043] In some preferred embodiments, the drying step is carried out in a tunnel drying oven at a temperature lower than the softening temperature of PETG; that is, the dyed PETG film is further dried at the softening temperature of PETG to allow the residual solvent to fully evaporate, resulting in a dyed PETG unidirectional calendered and stretched hard film, which is then wound up to obtain an ultra-thin dyed polarizing film; the lower the solvent content after drying, the better, such as 0%. Preferably, the drying temperature is 50℃-80℃.

[0044] In some preferred embodiments, a laminating and winding step is also included; the laminating and winding step includes: A protective film is bonded to one side of the polarizer, and a release film is bonded to the other side of the polarizer. Specifically, the lamination process involves laminating a protective film onto one side of the original film on a laminating machine, applying a surface adhesive onto the other side of the ultra-thin dye polarizer on a coating machine, laminating a release film on a laminating machine, and finally winding it up to obtain the ultra-thin dye polarizer product.

[0045] In some preferred embodiments, the above steps are performed within the same large exhaust hood to ensure timely removal of solvent evaporation during production. More preferably, the exhausted gases are condensed and recycled.

[0046] An ultra-thin polarizer processing system includes a first mixing vessel 1, a second mixing vessel 2, an extrusion coating machine 3, a casting machine 4, a calender 5, a drying oven 6, a winding machine 7, a coating machine 8, a laminating machine 9, and a second winding machine 10.

[0047] The specific working process is as follows: a first mixture is prepared in the first stirred tank 1; a second mixture and a third mixture are prepared in the second stirred tank 2; The third mixture is added to the extrusion coating machine 3, and the mixture is extruded from the slot and coated onto the casting machine 4. A thicker soft film with dye dissolved and dispersed in PETG is made on the slot extrusion casting machine. The thicker film is conveyed to the calender 5, and a unidirectional calendered and stretched PETG ultra-thin soft film with dye is made on the multi-stage double-roll heated calender. Then it is conveyed to the drying oven 6, and the PETG ultra-thin soft film is dried in the tunnel-type exhaust drying oven at the PETG softening temperature to allow the solvent to fully evaporate, resulting in a dyed PETG ultra-thin hard film (i.e., ultra-thin polarizing film). Then it is sent to the winding machine 7 for winding. The ultra-thin polarizing film, protective film, release film, and delay film are unwound; the composite adhesive and surface adhesive are applied through the ultra-thin polarizing film coating machine 8; then it is conveyed to the laminating machine 9 to laminate the protective film, release film, and delay film onto the ultra-thin polarizing film; after lamination, it is conveyed to the second winding machine 10 for winding, and the processing is completed.

[0048] An ultrathin circular polarizer includes the polarizer described above or the polarizer and retarder film prepared by the above method. Specifically, before laminating the release film, a composite adhesive is applied on a coating machine, and retarder films (λ / 2 and λ / 4 wave plates) are laminated on a laminating machine. Then, a surface adhesive is applied and a release film is laminated. Finally, the film is wound up to obtain the ultrathin circular polarizer product.

[0049] This invention proposes an ultrathin dye polarizer and its manufacturing method. Using liquid crystal dyes and PETG as raw materials, a mixture is prepared, a thick film is extruded, and the film is stretched into an ultrathin dye polarizer soft film through multi-stage roller calendering. After drying, an ultrathin dye polarizer hard film is obtained. Finally, a protective film, a delay film, and a release film are laminated to obtain an ultrathin circular polarizer. This invention achieves a novel structure different from existing sandwich structures, significantly reducing the polarizer thickness. Therefore, it is more suitable for the preparation of ultrathin circular polarizers for flexible display applications, solving the current challenges in the manufacturing and application of ultrathin circular polarizers. The raw materials used in this invention, such as liquid crystal dyes and PETG materials, as well as the diluents used, are all readily available commodities in the domestic market. The processing equipment used in this invention consists of mature chemical machinery equipment. Engineers in this industry have implemented this invention according to its description, provided they have the necessary experimental equipment. Therefore, this invention has real feasibility.

[0050] Example 1 This embodiment provides a method for manufacturing an ultrathin dye polarizer with a thickness of 30 μm and a width of 0.3 m.

[0051] The first step is ingredient preparation. At room temperature, 0.4 kg of black liquid crystal dye powder (provided by Guangdong Yunfu Lichang Dye Co., Ltd.) and 4.8 kg of propylene glycol methyl ether acetate (PGMEA) solvent (provided by Shandong Ruigang Chemical Co., Ltd.) are added to a 10L first stirred tank 1. The mixture is slowly stirred for 30 minutes to obtain the first mixture. Then, 20 kg of PETG granules (provided by Dongguan Juyu New Materials Co., Ltd.) and 80 kg of dichloromethane solution (provided by Jinan Zhengkang Chemical Co., Ltd.) are added to a 150L second stirred tank 2. The stirrer is started at 60 r / min for 12 hours to obtain the second mixture. The first mixture is then added to the second mixture, and stirring continues for 12 hours to obtain the third mixture. Stirring is stopped, and the mixture is allowed to stand for 24 hours to defoam, resulting in a dye-PETG mixture containing 105 kg of liquid crystal dye propylene glycol methyl ether acetate (PGMEA) diluted solution and PETG dichloromethane diluted solution. The dye solute accounts for 1.96% of the total PETG and dye solute.

[0052] The second step is coating. On the extrusion coating machine 3, the third mixture is extruded from the slit extrusion nozzle. The slit extrusion nozzle of the extrusion coating machine 3 has a gap of 90 μm and a width of 0.6 m. Figure 1As shown.

[0053] The third step is casting. The third mixture extruded from the extrusion coating machine 3 is coated onto the casting machine 4. The temperature of the casting machine 4 is set within the PETG softening temperature range of 80℃-88℃. The casting machine 4 is a stainless steel rotary casting machine, 0.75m in length and 1.5m in diameter, with a rotation speed of approximately 0.25r / min. Therefore, the output linear velocity of the cast film is approximately 1.2m / min. Figure 1 As shown, after the initial evaporation of the solvent, a relatively soft and thick PETG film with added dye is formed, with a thickness of approximately 90 μm and a width of 0.6 μm. Figure 2 As shown.

[0054] The fourth step is calendering and stretching. The dyed PETG thick film is unidirectionally calendered and stretched on a three-stage double-roll heated calender 5. The roll length is 0.75m and the diameter is ϕ0.25m. The roll gap is 70μm in the primary calender, 50μm in the intermediate calender, and 30μm in the end calender. The roll temperature is set to 80℃-88℃. The initial film feed speed is set to approximately 1.2m / min, the film flow speed between the primary and intermediate calender rolls is set to approximately 3.6m / min, and the film exit speed from the end calender is set to approximately 7.2m / min. That is, the primary calender roll speed is approximately 1.5r / min, the intermediate calender roll speed is approximately 4.5r / min, and the end calender roll speed is approximately 9r / min. The speed matching of each stage of the calender 5 rolls provides appropriate traction and stretching, resulting in a film with a thickness of 30μm and a width of 0.3m. Figure 2 The calendered and stretched film shown has an equivalent stretching ratio of approximately 6 times.

[0055] The fifth step is drying. The dyed PETG calendered and stretched soft film is conveyed into a tunnel-type exhaust drying chamber 6 via a conveyor belt at a speed of approximately 7.2 m / min. The drying chamber is approximately 10 m long, 1 m wide, and 0.5 m high. The temperature of the drying chamber is set below the softening temperature of the PETG film, such as 75°C. After passing through the drying chamber 6, the residual solvent in the dyed PETG film is fully evaporated. The film is then wound up by a winding machine 7 to obtain an ultra-thin dyed polarizing film base film with a thickness of approximately 30 μm, a width of approximately 0.3 m, a polarization degree of approximately 99%, and a light transmittance of approximately 40%.

[0056] Step 6: Lamination. Unwind the protective film and release film; Coating. Apply pressure-sensitive adhesive (also known as surface adhesive, with a thickness of approximately 20 μm) to one side of the ultrathin dye polarizer on coating machine 8; Lamination. Lay a 40 μm thick release film on laminating machine 9; Lay a 30 μm thick PE protective film on the other side of the ultrathin dye polarizer; Wind up. The result is an ultrathin dye polarizer product with a liquid crystal dye concentration of approximately 1.9% by mass in the PETG ultrathin film, an effective thickness of 30 μm, an actual thickness of approximately 110 μm, and a width of approximately 0.3 m.

[0057] Example 2 This embodiment provides a method for manufacturing an ultrathin circular polarizer with a thickness of 46 μm and a width of 0.3 m.

[0058] It includes the following steps: Steps one through five are the same as in Example 1. In step six, after laminating a 50μm thick PET protective film onto one side of an ultrathin dye polarizer with a thickness of approximately 30μm on the laminating machine 9, a layer of composite adhesive with a thickness of approximately 6μm is coated onto the other side on the coating machine 8. Then, a 2μm thick λ / 2 waveplate is laminated onto the laminating machine 9. The composite adhesive is then repeatedly coated onto the λ / 2 waveplate on the coating machine 8, with a thickness of approximately 6μm. The λ / 4 waveplate with a thickness of 2μm is then laminated onto the laminating machine 9. Finally, a surface adhesive is coated onto the λ / 4 waveplate, with a thickness of approximately 20μm. A 50μm thick PET release film is then laminated onto the film. The film is then wound up to obtain an ultrathin circular polarizer product with a liquid crystal dye concentration of approximately 1.9% in the PETG ultrathin film, an effective thickness of 46μm, an actual thickness of approximately 166μm, a width of 0.3m, a polarization degree of approximately 98%, and a light transmittance of approximately 38.5%.

[0059] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. An ultrathin dye polarizer, characterized in that, The polarizer comprises polyethylene terephthalate-1,4-cyclohexanediol ester (PETG) and a dichroic dye dispersed in the PETG by dissolution.

2. A method for preparing the ultrathin dye polarizer according to claim 1, characterized in that, The method for preparing the polarizer includes the following steps in sequence: Mixing, extrusion, coating, casting, unidirectional calendering, stretching and drying.

3. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, The mixing step includes: The dye is dissolved in the first solvent to obtain the first mixture; Polyethylene terephthalate-1,4-cyclohexanediethanol ester is dissolved in a second solvent to obtain a second mixture, wherein the second solvent and the first solvent are miscible; The first mixture and the second mixture are mixed evenly to obtain a third mixture, and the mixing is completed.

4. The method for preparing an ultrathin dye polarizer according to claim 3, characterized in that, The first solvent is propylene glycol methyl ether acetate; the second solvent is dichloromethane.

5. The method for preparing an ultrathin dye polarizer according to claim 3, characterized in that, The dye in the first mixture has a mass percentage content of 1%-10%; the PETG in the second mixture has a mass percentage content of 15%-35%.

6. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, The dye in the polarizer has a mass percentage content of 0.5%-5%.

7. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, The temperature of the casting machine in the casting process is 80℃-88℃.

8. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, In the extrusion and coating steps, the slit gap of the extrusion nozzle of the coating machine is 60μm-120μm.

9. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, The unidirectional calendering and stretching steps employ a multi-stage calender; along the conveying direction, the spacing between the calendering rollers of the multi-stage calender decreases sequentially, the linear speed increases sequentially, and the multi-stage calender is a heated calender with a heating temperature of 80℃-88℃.

10. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, The drying step is carried out in a tunnel drying oven at a temperature lower than the softening temperature of the PETG.

11. The method for preparing an ultrathin dye polarizer according to claim 2, characterized in that, It also includes a compounding step; The composite step includes: A protective film is bonded to one side of the polarizer, and a release film is bonded to the other side of the polarizer.

12. An ultrathin circular polarizer, comprising the polarizer of claim 1 or the polarizer and retarder prepared by any of the preparation methods of claims 2-11.

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