TWI247163B - Method for producing liquid crystal film, method for forming liquid crystal brightness enhancing film, and structure of liquid crystal film - Google Patents

Abstract

A method for producing a liquid crystal film is provided, including the steps of coating a layer of first liquid crystal material and a layer of second liquid crystal material on a first substrate and a second substrate respectively; laminating the first and second substrates in a manner that the liquid crystal material layers thereof face each other, so as to allow partial diffusion to occur between the first and second liquid crystal materials; performing an annealing process; and performing a curing process. Cholesterol liquid crystal can be used as the liquid crystal material in the above method to form a broadband reflective cholesterol liquid crystal brightness enhancement film that covers mostly the visible-light wavelengths. Repeated coating of the liquid crystal material on the substrate to form laminated liquid crystal films is not necessary, and therefore the time and the cost for producing the liquid crystal film can be reduced.

Description

1247163 MODIFICATION_Case No. 92130011 彳4年I^月3曰 V. OBJECTS OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method of producing a liquid crystal film, and a method of forming a brightness enhancement film by the method. In particular, a method of producing a cholesteric liquid crystal film using a cholesteric liquid crystal as a liquid crystal material, and a cholesteric liquid crystal brightness enhancing film which is effective for reflecting most of the visible light wavelengths. [Prior Art] Since liquid crystal displays (L i q u i d C r y s t a 1 D i s p 1 a y, L C D) have been widely used in various portable products, such as notebook computers, mobile phones, personal digital assistants and the like. Therefore, how to reduce the volume of the product and effectively reduce the power consumption rate, so that the user can carry it with him for a long time, has been the direction of research and development of various products. On the other hand, in order to achieve the requirement of full-color display, a high-light-absorbing film such as a color filter or a polarizer must be used in the liquid crystal display, wherein the polarizer reduces the intensity of the light source by about 50%, and the color filter is This will reduce the light source by approximately 6 6%. In order to maintain the brightness of the display, it is often necessary to increase the intensity of the light source in the backlight module, and consume a large amount of power, which not only causes the user to often have to worry about charging, but also shortens the service life of the illuminating original. At present, a reflective brightness enhancing film has been developed using cholesteric liquid crystal, and I is another method for increasing the brightness of a liquid crystal display. The term "cholesterol liquid crystal" refers to a liquid crystal material having a helix (he 1 i X ) structure of cholesterol, which includes adding an optically active liquid crystal molecule (chira 1 m ο 1 ecu 1 e ) to a multilayer nematic liquid crystal to make the multilayer nematic type. The long-axis directions of the molecules of each layer of the liquid crystal are gradually changed by one angle to form a spiral shape. Theoretically, a 100% unpolarized source of light enters a cholesterol with right-handed helix

] 7268 Jingmai.ptc Page 6 Correction 1247163 __ Case No. 92130011 V. Invention description (2) After liquid crystal, 50% of the right-handed circular polarized light will reflect, and 50% of the left-handed circular polarized light will penetrate. Taking the brightness enhancement film in the backlight module as an example, when the light source enters the reflective brightness enhancement film of the cholesteric liquid crystal from the backlight module, only the circularly polarized light opposite to the liquid crystal spiral structure can be used, and the circular polarization of the liquid crystal spiral structure is the same. Then, it is reflected back to the backlight module, and the reflected circular polarized light is reflected again by the reflective plate in the backlight module, so that the reflected circularly polarized light can be converted into a circularly polarized light of the opposite spiral, and the light source is recovered by the cholesteric liquid crystal solid film. The effect of reuse. After passing through the solid film of cholesteric liquid crystal, it is circularly polarized and cannot be directly applied to a liquid crystal display. It is required to be applied to a liquid crystal display by fitting a quarter-phase retarder to convert a circularly polarized light into a linearly polarized light. On the other hand, since the helical structure of the cholesteric liquid crystal itself has a different pitch (p i t c h ) P, incident light of a specific wavelength λ 〇 can be reflected. According to the Max we 1 1 theory, the relationship between the reflection wavelength λ 〇 and the pitch Ρ, the liquid crystal average refractive index n a is λ 〇 η η 3 X P , and the reflection wavelength Δ λ = Δ n a / η x P. However, the effective reflection range of a single type of cholesteric liquid crystal for visible light wavelength is about 80 nm; in practice, it is often only 30 to 50 nm, which cannot effectively reflect all visible light under the requirements of full color display. The wavelength range. In order to enable the cholesteric liquid crystal brightness enhancement film to effectively reflect most of the light source in the visible light wavelength range, it is often necessary to repeatedly apply multiple times of the cholesteric liquid crystal polymer of different pitches. In general, it is necessary to form 4 to 6 layers of liquid crystal laminates of different formulations to produce effective reflection for visible light having a wavelength range of 450 nm to 750 nm. When a 6-layer liquid crystal laminate is applied to form a brightness enhancement film, it is necessary to repeat the same process steps six times, which is time consuming and consumable.

] 7268 精迈.ptc Page 7 1247163 Case No. 9213001] Year, February 1st Revision 5. Invention Description (3) This is also not conducive to controlling the quality and effect of each layer of liquid crystal layer, often resulting in a reduction in production yield. Therefore, there is still a need for a cholesterol liquid crystal brightness enhancing film which is effective for most of the visible wavelengths to be produced in a simple and rapid manner. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of producing a liquid crystal film which does not require repeated coating to form a multilayer liquid crystal laminate. Another object of the present invention is to provide a method of producing a liquid crystal film which does not require repeated coating to form a multilayer liquid crystal layer, so that the obtained liquid crystal film can be effectively reflected for most visible light wavelengths. Another object of the present invention is to provide a method of forming a cholesteric liquid crystal brightness enhancing film which is effective for most of the visible light wavelength. A further object of the present invention is to provide a liquid crystal film structure comprising first and second liquid crystal materials respectively disposed between a first substrate and a second substrate and coated on the first and second substrates, respectively. The interface portion of the first liquid crystal material and the second liquid crystal material is diffused to form a mixture. Still another object of the present invention is to provide a liquid crystal film structure comprising first and second cholesteric liquid crystal materials respectively coated on a first substrate and a second substrate between a first substrate and a second substrate, wherein The interface portion between the first cholesterol liquid crystal material and the second cholesterol liquid crystal material is diffused to form a mixture, and any one of the first substrate and the second substrate is a quarter phase retarded film substrate . To achieve the above object, the method for producing a liquid crystal film of the present invention comprises the steps of: coating the first and second liquid crystal materials on the first and second portions, respectively.

] 7268 Jingmai.ptc Page 8 1247163 Wide _ Case No. 92130011 L / Dou Nian [^月\日_iMi_ V. Invention Description (4) Substrate, so that the coating has the basis of the brother and the second liquid crystal material The material is bonded in a manner opposite to the liquid crystal material layer, and a partial diffusion and mixing between the first and second liquid crystal materials is performed; a tempering process is performed; and a curing process is performed. The method of the present invention is to select the first and second liquid crystal materials capable of reflecting different wavelengths, and respectively apply the first and second liquid crystal materials to the first and second substrates, and then make the first and the second The two substrates are bonded and tempered in a manner opposite to the liquid crystal material layer, and the partial diffusion and mixing generated by the first and second liquid crystal materials do not need to be repeatedly applied to form a multilayer liquid crystal laminate, that is, A liquid crystal film having excellent reflection characteristics can be obtained by a simple method. On the other hand, if the first and second cholesterol liquid crystal materials and the quarter-phase retarded film substrate are used as needed, the method can be used to form a cholesteric liquid crystal brightness enhancing film which can effectively reflect most of the visible light wavelength. [Embodiment] The embodiments of the present invention are described in the following specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the disclosure of the present specification. The present invention may be embodied or applied in various other specific embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention. The method for producing a liquid crystal film according to the present invention is to first apply the first and second liquid crystal materials to the first and second substrates, respectively. The types of the first and second liquid crystal materials include nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, and the like. As far as cholesterol liquid crystals are concerned, due to different types of cholesterol liquid crystal materials themselves

] 7268 精迈.ptc Page 9 1247163 Case No. 92] 30011 I 0 month 'day correction / 5, invention description (5) pitch difference, will reflect the light source of a specific wavelength; therefore, the present invention As a specific example, a cholesteric liquid crystal material having a reflection characteristic for a shorter wavelength blue light is selected as the first liquid crystal material, and a cholesteric liquid crystal material having a reflection characteristic for a longer wavelength of red light is selected as the second liquid crystal material. And coating the first and second liquid crystal materials on the first and second substrates respectively, followed by performing a bonding and tempering step, causing partial diffusion mixing between the first and second liquid crystal materials, and mixing and mixing The liquid crystal material has a reflective property for green wavelength visible light having a wavelength between blue light and red light, thereby forming a cholesteric liquid crystal film having reflection characteristics for most visible light wavelengths. In the method of the present invention, the selected liquid crystal material and the photoinitiator may be first dissolved in a suitable solvent and then coated in a dispersed state, or a photopolymerizable liquid crystal material may be selected and dissolved in a suitable solvent to form a dispersion. In the form of a state, or directly heating and melting the liquid crystal material, it is applied in a molten state. The solvent may be selected depending on the nature of the liquid crystal material and the kind of the substrate to be used, and examples thereof include, but are not limited to, toluene, tetrahydrofuran, cyclohexane, cyclopentanone, and dinonylbenzene. When the liquid crystal material is dissolved in a suitable solvent and then applied in a dispersed form, the ratio of the liquid crystal material to the solvent is not particularly limited, and is generally preferably in a similar ratio; if the amount of the solvent is too large, it is likely to occur. Incomplete solvent removal, if the amount of solvent is insufficient, the dispersion effect of the liquid crystal material is not good. The ratio of such liquid crystal materials to the solvent and the type of solvent selected may be adjusted and selected by those skilled in the art as needed or by experience.本 The method of the present invention may use a solid carrier, a flexible carrier, or

] 7268 精, ptc 第]0页1247163 Amendment No. 92130011 V. Invention Description (6) As a substrate for coating a liquid crystal material, including using an optically wearing smooth glass plate or a plastic substrate as a coating liquid crystal material Examples of the substrate substrate include, but are not limited to, poly(p-benzoate) (PET), polycarbonate (PC), polyether maple (PES), polymethyl ester (PMMA), and poly 2 , such as 6-naphthalene diacetate (PEN), such as having a light transmittance of more than 85%, an optical transmittance of more than %, and more preferably more than 95% Degree. When using a plastic substrate, it is preferred to first apply the alignment film or directly perform mechanical friction on the plastic, for example, using a fluff roller, a friction unit with a soft surface for fixing the structure of the fiber, and an alignment film surface or a plastic base to be coated. The surface of the material is mechanically rubbed, or aligned by field, magnetic field, stress, etc., so that the subsequent application to the material has a substantially alignable alignment direction. Whether a liquid crystal material in a dispersed state or a material in a molten state is used, the liquid crystal materials may be coated by various applicators, such as a slit coater, a roll slit coater, Cloth and so on. In the case of a liquid crystal material in a dispersed state, the slit type slit coating method is used in a closed system to reduce the problem of an increase in the solid content of the solvent; and at the same time, the coating method of the slit coating method, As well as the advantages of high speed and high uniformity, it is adopted by the world. If the liquid crystal material is first dissolved in a suitable solvent and then coated, it is preferred to completely dissolve the liquid crystal material in the dispersed state, and then apply the solvent, and then remove the solvent under appropriate temperature conditions to form a viscous shape. Liquid crystal film. High penetration. In the case of plastic acid glycol, yttrium acrylate. Generally, it is more preferable that the liquid crystal material of the 90 optically penetrating adhesive substrate or the liquid crystal material is applied with a liquid crystal material, and the liquid crystal material is volatilized in the base and the gravure coating applicator, and the diversification is more often carried out in the industrial state. Defoaming and baking

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I Π 268 Jingmai. ptc Page 1 page 1247163 Case No. 92130011 Amendment 5, invention description (7) In the present invention, respectively, applied to the first cooling step, in 10 seconds, to make the liquid crystal material The preferred method of the bonding process is to determine the thickness of the liquid crystal film and the second substrate. The liquid crystal gap is as long as the coating is applied to the first substrate and the second substrate. The temperature of the material can be broken, and again, the liquid film formed by the first liquid crystal material is adjusted. Usually, the second liquid level drops below room temperature. A material of the liquid crystal material overflows due to the pressure. For example, when using (5 80 to 6 60 η m) of the gallbladder, respectively, the 0.5 to 5 kg of the laminating machine is treated with a liquid crystal material, so that the diffused visible light of 600 nm) The second substrate coated with the first liquid material is also affixed, but is not limited to: having a roller contact type and a web process, so that the liquid crystal is aligned with the liquid crystal pressure, according to the selected one. After the reflective surface material is mixed with the pressure surface of only two liquid reflective alcohol liquid crystals with the first material, the cooling section is in the same manner. The material layer is opposite to and adheres to the temperature of the liquid crystal material for the liquid crystal material. The liquid crystal material portion produces a complete blue light of the crystallizing material (440 to the material as the first and 75 to 85 ° C for liquid crystal material pair properties. Liquid, the cold. Then the substrate and the gap are not material and the thick and pressure substrate is mixed and melt mixed crystal is thin, and then coated for special substrate degree and paste, and 510nm And a tunnel that is bonded to the temperature condition of the second liquid, and then passed through the first substrate having a green wavelength and the first cycle coated with the first tempered single box and the gas pair, and is processed by the process. The type of tempering and tempering single-cycle tempering and crystallization material film is used for the second step. After the limitation, the type and the required bonding, there is no liquid crystal condition, that is, red light crystal material, which is favorable for tempering (500 to 2 liquid crystal element flow type, ring tempering at temperature)

Π268 精迈.ptc 12 I 1247163 Case No. 92130011 β屮年 l 〇月曰曰 correction / V, invention description (8) The difference is above 40 °C, preferably above 50 °C, more preferably 6 The first tempering temperature above 0 ° C is performed at a relatively low second tempering temperature. The first and second tempering temperatures are not particularly limited. If a plastic substrate is used, the temperature of the tempering treatment is usually not higher than the glass transition temperature of the plastic substrate used and the liquid crystal molecules can be oriented. Arrange. The first tempering temperature and the second tempering temperature are preferably in the range of 10 ° C to 13 3 , more preferably in the range of 2 or 11 ° ° C. In the tempering process, the time of the first tempering temperature is generally 1.5 to 2.5 times, and the number of times of the tempering treatment is not particularly limited. It is preferably 5 to 15 times, and more preferably 20 to 30 times. If the temperature is tempered only at a single temperature, or the number of cycles of tempering is too low, the surface of the liquid crystal film after curing may be poorly transmitted, causing problems such as scattering of incident light. On the other hand, if the number of times of the tempering treatment is too large, a liquid crystal film having a good light transmittance can be obtained, but the production time is prolonged, resulting in a decrease in production efficiency. The liquid crystal film which has been oriented by cyclic tempering is cured by radiation irradiation to initiate a crosslinking reaction. Radiation sources of different wavelengths are selected depending on the type of photoinitiator used or the photopolymerizable liquid crystal material selected. Suitable light source sources include radiation sources having a wavelength of from 280 to 700 nm; for example, but not limited to, ultraviolet light, X-rays, electron beams, lasers, and the like. The cholesteric liquid crystal film obtained by the method of the present invention can be used to form a brightness enhancement film used in a liquid crystal display. The method for forming the brightness enhancing film comprises: laying high transparent optics on the formed solid film of cholesteric liquid crystal

1247163 _ Case No. 92130011 Θ令年月日 Revision _ V. Invention Description (9) Glue, and then use a bonding unit, such as a laminating machine, to bond a quarter phase retardation film to a liquid crystal solid film; or directly A film substrate coated with a quarter phase retardation is used as a substrate coated with the first or second cholesteric liquid crystal material, and a cholesteric liquid crystal film is produced by the method of the present invention to form a brightness enhancement film. Examples of the transparent optical adhesive include, but are not limited to, NI Ρ Ρ NG Ο Ο manufactured by HSEI, under the trade names COPONYL 5 8 5 9 Β, COPONYL Ν-2233, COPONYL Ν-2147, COPONYL Ν-3816, COPONYL Ν-4122 , COPONYL Ν-4144, and UV-3620ID70 sales of transparent optical adhesive. The quarter-phase retardation film to be used is not particularly limited as long as it can convert a circularly polarized light passing through a solid film of a cholesteric liquid crystal into a linearly polarized light, for example, RETARDATION FILM (manufactured by Teijin Co., Ltd., under the trade name) T-127, T-138, T-278, W-141, W-147, M-137 sellers), ARTON FILM (made by JSR Japan), C0C (made by Mitsui Chemicals Co., Ltd.). The following examples are intended to describe the various aspects of the invention in detail and are not intended to limit the scope of the invention. (Examples) The liquid crystal material used in the examples is as follows. The liquid crystal material 1 is a nematic cholesteric liquid crystal which reflects the blue light wavelength and has a center-to-column cholesteric liquid crystal. The spectral test results are shown in Fig. 1. The liquid crystal material 2 refers to a nematic cholesteric liquid crystal which can reflect the red light wavelength with respect to the center of the palm, and the spectral test results are shown in Fig. 2. (Preparation Example 1) 100 g of the liquid crystal material 1 was dissolved in 100 g at room temperature.

] 7268 Jingmai.ptc Page 14 Amendment 曰 1247163 ___ Case No. 92130011 V. Invention Description (10) In the hydrogen furan, add 5 grams of light initiator (manufactured by Ciba, under the trade name 11^人〇11 ^ 9 0 7 sold photoinitiator), dissolved to form a cholesteric liquid crystal solution. The cholesteric liquid crystal solution is quantitatively delivered to the slit coater by a metering pump system, and the cholesteric liquid crystal solution is applied to the warp roller to rub the polyparaphenylene having an optical transmittance of 90% or more by the coating head. Ethyl citrate (PET) substrate. The solvent was removed by baking at 100 °C. Then, the temperature is rapidly lowered to 20 ° C in 1 〇 second to form a solid first liquid crystal film. (Preparation Example 2) 100 g of the liquid crystal material 2 was dissolved in 100 g of tetrahydrofuran at room temperature, and then 5 g of a photoinitiator (manufactured by Ciba Corporation under the trade name IRG A CURE) was added. 907 sold the photoinitiator) to dissolve it to form a cholesteric liquid crystal solution. The cholesteric liquid crystal solution was quantitatively fed to the slit coater by a metering pump system. The cholesteric liquid crystal solution was applied to a quarter-refractive film substrate rubbed by a pile roller by a coating head. The solvent was removed by baking at 10 °C. Then, the temperature was rapidly lowered to 20 ° C in 10 seconds to form a solid second liquid crystal film. (Example 1) Using a pressure bonding apparatus, a pressure of 5 kg and a temperature of 80 ° C were used to bond the liquid crystal film of the same body to the liquid crystal material. Then, cyclic tempering treatment was carried out 10 times at 20 ° C and 1 1 (TC temperature for 10 minutes. The exposure process was carried out using ultraviolet light of 3 6 5 ηπι, and solidified cholesterol was formed after cross-linking curing reaction. Liquid crystal film, the light selection effect of the cholesteric liquid crystal film is tested by a spectrometer, and the result is as follows

Π268 精迈.ptc第15页

Revision month; 曰 1247163 _ Case number 92130011 V. Invention description (11) Figure 3. As can be seen from the result of FIG. 3, a liquid crystal film is separately formed by using a cholesteric liquid crystal material selective for blue wavelength and a cholesteric liquid crystal material having selectivity for red wavelength, and then laminated in such a manner that the liquid crystal material faces each other. The process and tempering process can form a cholesteric liquid crystal brightness-enhancing film which can effectively reflect visible light having a wavelength of 450 to 65 nm without repeating multiple coatings to form a laminate. The above-described embodiments are merely illustrative of the principles of the invention and its advantages, and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the patent application to be described later.

] 7268 精迈.ptc Page 16 1247163 Case No. 921300Π Year [October date Correction ' / Simple description of the drawing [Simple description of the drawing] Figure 1 is a spectrum test chart of liquid crystal material 1. Figure 2 is a spectrum test chart of liquid crystal material 2. Fig. 3 is a spectroscopy test chart of a cholesteric liquid crystal brightness-increasing film obtained according to a specific example of the present invention. (The pattern in this case has no component symbol)

]7268 Jingmai.]nc第第7页

Claims (1)

(More) 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 Forming the first and second liquid crystal materials into a solid liquid crystal film; bonding the substrate coated with the first and second liquid crystal materials in a manner opposite to the liquid crystal material layer, and bonding the first and second liquid crystal materials Partial diffusion mixing occurs, a tempering process is performed; and a curing process is performed. 2. The method of claim 1, wherein the first and second liquid crystal materials are cholesteric liquid crystal materials. 3. The method of claim 2, wherein the first liquid crystal material has a characteristic of reflecting a shorter wavelength than the second liquid crystal material. 4. The method of claim 1, wherein the substrate is a plastic substrate. 5. The method of claim 4, wherein the surface of the plastic substrate is rubbed by a pile roller. 6. The method of claim 1, wherein the liquid crystal material is applied to the substrate by a slit coating method. 7. The method of claim 1, wherein the first and second liquid crystal materials are applied to the substrate and cured at a low temperature to form a solid thin film. ] 7268 精迈.plx Page 18 1247163 η, _ Case No. 92130011_一/斗年Ρ月$曰修正_6. Patent application scope 8. The method of claim 1, wherein the bonding system The bonding apparatus is used under the condition that the first liquid crystal material and the second liquid crystal material are partially diffused and mixed. 9. The method of claim 1, wherein the tempering process is cyclic tempering at a first tempering temperature above a temperature difference of 40 ° C and a relatively low second tempering temperature. The method of claim 1, wherein the curing process is performed by radiation irradiation. The method of claim 10, wherein the radiation is selected from the group consisting of ultraviolet light, X-rays, electron beams, and lasers. 1 2. A method for forming a brightness enhancing film, comprising the steps of: applying first and second liquid crystal materials to the first and second substrates, respectively, performing a cooling step to make the first and second liquid crystal materials Forming a solid liquid crystal film; and one of the first and second substrates is a quarter-phase retarded film substrate; and the substrate coated with the first and second liquid crystal materials is opposite to the liquid crystal material layer The method is performed to form a partial diffusion mixture between the first and second liquid crystal materials; performing a tempering process; and performing a curing process. The method of claim 12, wherein the first and second liquid crystal materials are bile solid Sf. liquid crystal materials. The method of claim 13, wherein the first liquid crystal material !11| II 17268 精迈.ptc Page 19 Amendment 1247163 _ Case No. 92130011 t, Patent Application The material has a characteristic of reflecting shorter wavelengths than the second liquid crystal material. The method of claim 12, wherein the first and second liquid crystal materials are applied to the substrate and cured at a low temperature to form a solid film. The method of claim 12, wherein the bonding is performed by using a bonding apparatus in a condition in which the liquid crystal material and the second liquid crystal material are partially diffused and mixed. The method of claim 12, wherein the tempering process is cyclic tempering at a first tempering temperature above a temperature difference of 40 ° C and a relatively low second tempering temperature . The method of claim 12, wherein the curing process is performed by radiation irradiation. The method of claim 18, wherein the radiation is selected from the group consisting of ultraviolet light, X-rays, electron beams, and lasers. a liquid crystal film structure comprising first and second liquid crystals between a first substrate and a second substrate, respectively coated on the first and second substrates and cooled to form a solid liquid crystal film And a material, wherein an interface portion between the first liquid crystal material and the second liquid crystal material is diffused to form a mixture when the first and second substrates are bonded together. 2 1. The liquid crystal film structure of claim 20, wherein the first and second liquid crystal materials are cholesteric liquid crystal materials. 2 2. The liquid crystal film structure of claim 21, wherein the Π268 精迈.ptc Page 20 1247163 Case No. 921300Π a Correction Patent Range One of the substrate and the second substrate is a thin film substrate with a quarter phase retardation. ]7268 Jingmai.ptc Page 21 111