Novel double-band liquid crystal reflecting film for automobile

Abstract

The invention relates to the technical field of liquid crystal, and particularly discloses a novel automotive biband liquid crystal reflecting film which is prepared by the following steps: S1, preparing a substrate which is made of any one of epoxy liquid crystal molecules and acrylic acid liquid crystal molecules, and ensuring that the surface of the substrate is clean and flat; s2, preparing liquid crystal coating liquid; s3, liquid crystal coating is conducted, specifically, any one of a spin coater, a slit coater or an ink-jet printer is used for evenly coating the substrate in the step S1 with liquid crystal coating liquid; s3, drying and curing are carried out; and S4, carrying out post-treatment. The production cost is reduced by using a relatively accurate proportion and accurate control of a plurality of steps and utilizing a coating mode, and the coating is accurate, so that high reflectivity can be realized in two different spectral bands, light in two specific wavelength ranges can be reflected at the same time, the utilization rate of light in different colors is effectively improved, the reflected light is more uniform, and the quality of the product is improved. And the color expression is richer and more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystals, and in particular to a novel dual-band liquid crystal reflective film for automobiles. Background Art

[0002] The dual-band liquid crystal reflective film is a thin film material with special optical properties. It mainly utilizes the arrangement characteristics of liquid crystal molecules to achieve reflection of specific spectral bands. Liquid crystal molecules can change their orientation under different electric fields, temperatures or other external conditions, thereby changing the optical constants of the film, such as the refractive index. Through reasonable design and preparation processes, it can produce reflection phenomena in two different spectral bands.

[0003] At present, the following deficiencies still exist in the preparation process of the dual-band liquid crystal reflective film for automobiles: The preparation process of the dual-band liquid crystal reflective film involves multiple steps and precise proportioning and processing of various materials, such as the selection and mixing of liquid crystal molecules, the addition of chiral dopants, the use of photoinitiators, and precise coating, drying and curing processes. These complex preparation processes not only increase the production cost, but also pose high requirements on the production environment and equipment, resulting in relatively low production efficiency, being difficult to mass-produce industrially, and the control of temperature and humidity is relatively important during the preparation. A high-humidity environment may cause the liquid crystal reflective film to absorb moisture, thereby affecting the arrangement of liquid crystal molecules and the structure of the film layer. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] A novel dual-band liquid crystal reflective film for automobiles comprises the following steps:

[0006] S1. Prepare a substrate, the substrate material includes any one of epoxy liquid crystal molecules and acrylic liquid crystal molecules, and ensure that its surface is clean and flat;

[0007] S2. Prepare a liquid crystal coating solution, the proportion of the liquid crystal material to the coating solution is 3:7, and a stabilizer is added, and the stabilizer accounts for 0.1%-5% of the total mass of the coating solution;

[0008] Add a leveling agent, and the proportion of the leveling agent is 0.5%-3%;

[0009] Add a coupling agent, and the proportion of the coupling agent is 0.2%-2%;

[0010] S3. Coating liquid crystal: Use any one of a spin coater, a slot coater, or an inkjet printer to uniformly coat the liquid crystal coating solution on the substrate in the S1 step.

[0011] S3. Perform drying and curing: Dry the substrate coated with liquid crystal to remove the solvent and form a uniform liquid crystal film layer.

[0012] S4. Post-treatment: Cut and package the cured liquid crystal film.

[0013] As a preferred technical solution of the present invention, the thickness of the substrate in the S1 step accounts for 30%-50% of the thickness of the entire reflective film structure.

[0014] As a preferred technical solution of the present invention, the coating solution in S2 includes preparing a mixed solution, which includes: epoxy liquid crystal molecules, one or more of liquid crystal compounds 1, 2, 3, and 4; chiral dopants, such as any two of chiral dopants 1, 2, 3, and 4; chiral dopants with different end groups, such as chiral dopant 1, chiral dopant 2, chiral dopant 3, and chiral dopant 4, etc. Adjust the relative position of the two reflection bands by adjusting their relative content and overall content.

[0015] Determine the types and ratios of photoinitiators, photoinitiator assistants, and free radical photoinitiators; select solvents, with the mass ratio of cyclopentanone to cyclohexanone being 4:1, or the mass ratio of cyclohexanone to ethyl acetate being 4:1. Mix the above components in a certain ratio to prepare a mixed solution.

[0016] As a preferred technical solution of the present invention, in the S3 step, first uniformly coat the mixed solution on the substrate, heat and volatilize the substrate coated with the mixed solution at 90-120°C to remove the solvent, irradiate the heated and volatilized substrate with a high-pressure mercury lamp for 10-20 s to initiate a photo-crosslinking polymerization reaction to form a polymer thin film material, and irradiate the polymer thin film material with ultraviolet light of 365 nm at 80-130°C.

[0017] As a preferred technical solution of the present invention, two drying processes are required in the S3 step. The first drying: Heat and volatilize the coated substrate at 90-120°C to remove the solvent, which is carried out in an oven for 8-16 minutes; the second drying: Irradiate the substrate after photo-crosslinking polymerization with ultraviolet light of 365 nm at 80-130°C, and this process is carried out in an ultraviolet curing box for usually 35 seconds to 3 minutes.

[0018] As a preferred technical solution of the present invention, in the step S3, dual curing is performed, including photocuring and thermal curing. The photocuring: irradiate the substrate after heating and volatilization with a high-pressure mercury lamp for 10 - 20 s to initiate a photocrosslinking polymerization reaction to form a polymer thin film material; the thermal curing: irradiate the substrate that has undergone photocuring with ultraviolet light of 365 nm at 80 - 130 °C to obtain a bilayer liquid crystal film.

[0019] As a preferred technical solution of the present invention, in the step S1, the liquid crystal molecules include epoxy liquid crystal molecules such as liquid crystal compound 1, liquid crystal compound 2, liquid crystal compound 3, liquid crystal compound 4, etc., and acrylic liquid crystal molecules of the general formula.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: by using relatively accurate proportions and precise control of multiple steps, and using a coating method to reduce production costs, and precisely coating, high reflectivity can be achieved in two different spectral bands, and light of two specific wavelength ranges can be reflected simultaneously, effectively improving the utilization rate of light of different colors, making the reflected light more uniform, and the color performance more rich and accurate;

[0021] Due to its high-efficiency light reflection characteristics, the use power of the backlight can be reduced in display applications, energy consumption can be reduced, and the battery life of the device can be extended, meeting the requirements of modern society for energy conservation and environmental protection; the dual-band liquid crystal reflection film usually has a relatively thin thickness and a light weight, is easy to integrate into various thin and light electronic devices, and will not significantly increase the volume and weight of the device, meeting the trend of modern electronic products towards thinness, lightness, and portability, and providing greater flexibility for product design.

[0022] Other features and advantages of the present invention will be described in the subsequent description, and some of them will become obvious from the description or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written description and the accompanying drawings. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0024] Figure 1 It is a flow schematic diagram of the present invention. Detailed Embodiments

[0025] The preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, where the drawings form a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention.

[0026] Referring to Figure 1 , the present invention provides a novel dual-band liquid crystal reflective film for automobiles, characterized by including the following steps:

[0027] S1. Prepare a substrate, the substrate material includes any one of epoxy liquid crystal molecules and acrylic liquid crystal molecules, and ensure that its surface is clean and flat;

[0028] S2. Prepare a liquid crystal coating solution, the proportion of the liquid crystal material to the coating solution is 3:7, and a stabilizer is added, and the stabilizer accounts for 0.1%-5% of the total mass of the coating solution;

[0029] Add a leveling agent, and the proportion of the leveling agent is 0.5%-3%;

[0030] Add a coupling agent, and the proportion of the coupling agent is 0.2%-2%;

[0031] S3. Coat the liquid crystal, use any one of a spin coater, a slot coater or an inkjet printer to uniformly coat the liquid crystal coating solution on the substrate in the S1 step;

[0032] S3. Perform drying and curing, dry the substrate coated with the liquid crystal to remove the solvent, and make the liquid crystal form a uniform film layer;

[0033] S4. Post-treatment, cut and package the cured liquid crystal film.

[0034] The thickness of the substrate in the S1 step accounts for 30%-50% of the thickness of the entire reflective film structure.

[0035] It should be noted that, for example, when using a mass ratio, if the liquid crystal material accounts for 30% of the mass of the coating solution, the solvent accounts for 70%. This ratio can be adjusted according to the solubility of the liquid crystal material and the requirements of the coating process. If the solubility of the liquid crystal material is good and it is desired that the coating solution has a lower viscosity for easy coating operations, such as fine coating methods like slot coating or inkjet printing, the proportion of the liquid crystal material can be appropriately reduced and the proportion of the solvent can be increased. On the contrary, if it is desired that the liquid crystal material content in the coating solution is high to reduce shrinkage during subsequent drying and improve the thickness accuracy of the liquid crystal layer, the proportion of the liquid crystal material can be appropriately increased;

[0036] Some additives such as stabilizers, leveling agents or coupling agents will be added to the coating solution to improve the performance of the coating solution and the quality of the liquid crystal layer.

[0037] The addition amount of the stabilizer is usually small, probably about 0.1%-5% of the total mass of the coating solution. Its main function is to prevent the liquid crystal material from decomposing or deteriorating in performance during storage or coating. For example, for some temperature-sensitive liquid crystal materials, adding an appropriate amount of heat stabilizer can ensure that the liquid crystal material still maintains good performance even when the temperature fluctuates during the coating process.

[0038] The proportion of the leveling agent may be about 0.5%-3%. It helps the coating solution form a more uniform coating on the substrate surface and reduces surface defects. During the spin coating process, adding a leveling agent can make the liquid crystal coating solution spread better on the substrate surface under high-speed rotation, resulting in a smoother liquid crystal layer.

[0039] The coupling agent is mainly used to enhance the adhesion between the liquid crystal layer and the substrate. Its addition amount is usually between 0.2%-2%. For example, in the combination of some glass substrates or plastic substrates and the liquid crystal layer, adding a coupling agent can improve the interfacial performance between the two and prevent the liquid crystal layer from peeling off the substrate during use.

[0040] The coating solution in S2 includes preparing a mixed solution, which includes: epoxy liquid crystal molecules, one or more of liquid crystal compounds 1, 2, 3, 4; chiral dopants, such as any two of chiral dopants 1, 2, 3, 4; chiral dopants with different end groups, such as chiral dopant 1, chiral dopant 2, chiral dopant 3, and chiral dopant 4, etc. By adjusting their relative content and overall content, the relative positions of the two reflection spectral bands are adjusted;

[0041] Determine the types and proportions of the photoinitiator, photoinitiator assistant, and free radical photoinitiator; select solvents, with the mass ratio of cyclopentanone to cyclohexanone being 4:1, or the mass ratio of cyclohexanone to ethyl acetate being 4:1. Mix the above components in a certain proportion to prepare a mixed solution.

[0042] In the S3 step, first, the mixed solution is evenly coated on the substrate. The substrate coated with the mixed solution is heated and volatilized at 90-120°C to remove the solvent. Then, the heated and volatilized substrate is irradiated with a high-pressure mercury lamp for 10-20 s to initiate a photo-crosslinking polymerization reaction to form a polymer thin film material. The polymer thin film material is irradiated with ultraviolet light of 365 nm at 80-130°C.

[0043] In the S3 step, two drying processes are required. The first drying: The coated substrate is heated and volatilized at 90-120°C to remove the solvent, which is carried out in an oven for 8-16 minutes; the second drying: The substrate after photo-crosslinking polymerization is irradiated with ultraviolet light of 365 nm at 80-130°C. This process is carried out in an ultraviolet curing box and usually takes 35 seconds to 3 minutes.

[0044] It should be noted that the coating process requirements: Different coating processes have different requirements for the physical properties of the coating solution, such as viscosity and surface tension. For example, the spin coating process usually requires a coating solution with a lower viscosity, so it may be necessary to increase the proportion of the solvent; while the slot coating process has higher requirements for the fluidity and stability of the coating solution, and it may be necessary to appropriately adjust the proportions of the liquid crystal material, solvent, and additives to obtain suitable rheological properties.

[0045] Liquid crystal material characteristics: The properties of the liquid crystal material itself, such as solubility and phase transition temperature, will also affect the preparation ratio of the coating solution. If the solubility of the liquid crystal material is poor, it may be necessary to select a special solvent or increase the proportion of the solvent. At the same time, it may also be necessary to add a co-solvent to improve its solubility. In addition, for some liquid crystal materials with a lower phase transition temperature, temperature control needs to be considered during the preparation of the coating solution, and appropriate stabilizers need to be added to prevent the liquid crystal from undergoing a phase transition during the coating process.

[0046] Final requirements for the reflective film performance: The optical performance, mechanical performance, etc. of the dual-band liquid crystal reflective film will also affect the ratio of the coating solution. If it is necessary to increase the reflectivity of the reflective film, it may be necessary to increase the proportion of the liquid crystal material to form a thicker liquid crystal layer; if the reflective film is required to have good flexibility, it may be necessary to adjust the proportions of the solvent and additives to make the liquid crystal layer have a better bond with the substrate and make the entire reflective film have appropriate flexibility.

[0047] In the S3 step, dual curing is carried out, including photo-curing and thermal curing. The photo-curing: irradiate the substrate after heating and volatilization with a high-pressure mercury lamp for 10 - 20 s to initiate a photo-crosslinking polymerization reaction to form a polymer thin film material; the thermal curing: irradiate the substrate that has undergone photo-curing with ultraviolet light of 365 nm at 80 - 130 °C to obtain a double-layer liquid crystal thin film.

[0048] The liquid crystal molecules in the S1 step include epoxy liquid crystal molecules such as liquid crystal compound 1, liquid crystal compound 2, liquid crystal compound 3, liquid crystal compound 4, etc., and acrylic liquid crystal molecules of the general formula.

[0049] By using relatively accurate proportions and precise control of multiple steps, and using the coating method to reduce production costs and precisely coat, high reflectivity can be achieved in two different spectral bands, and it can simultaneously reflect light in two specific wavelength ranges, effectively improving the utilization rate of different colors of light, making the reflected light more uniform, and the color performance more rich and accurate;

[0050] Due to its efficient light reflection characteristics, it can reduce the power consumption of the backlight source in display applications, lower energy consumption, and extend the battery life of the device, meeting the requirements of modern society for energy conservation and environmental protection; the dual-band liquid crystal reflection film usually has a relatively thin thickness and a light weight, making it easy to integrate into various thin and light electronic devices without significantly increasing the volume and weight of the device, meeting the trend of modern electronic products towards thinness and portability, and providing greater flexibility for product design.

[0051] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0052] The terms "first", "second", "third", "fourth", etc. (if any) in the description of the embodiments of this application, the claims and the above drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the embodiments of this application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0053] In the embodiments of this application or what is implied, the device or element must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the embodiments of this application. In the description of the embodiments of this application, the meaning of "a plurality" is two or more, unless otherwise specifically and precisely defined.

[0054] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not elaborate on all the details, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. The present specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A novel dual-band liquid crystal reflective film for automobiles, characterized in that: It includes the following steps: S1. Prepare a substrate. The substrate material includes any one of epoxy liquid crystal molecules and acrylic liquid crystal molecules, and ensure that its surface is clean and flat. S2. Prepare a liquid crystal coating solution. The proportion of the liquid crystal material to the coating solution is 3:7, and a stabilizer is added. The stabilizer accounts for 0.1%-5% of the total mass of the coating solution. Add a leveling agent, and the proportion of the leveling agent is 0.5%-3%. Add a coupling agent, and the proportion of the coupling agent is 0.2%-2%. S3. Coat the liquid crystal. Use any one of a spin coater, a slot coater, or an inkjet printer to evenly coat the liquid crystal coating solution on the substrate in step S1. S3. Perform drying and curing. Dry the substrate coated with the liquid crystal to remove the solvent and make the liquid crystal form a uniform film layer. S4. Perform post-treatment. Cut and package the cured liquid crystal film.

2. The novel dual-band liquid crystal reflection film for automobiles as described in claim 1 is characterized in that: In step S1, the thickness of the substrate accounts for 30%-50% of the thickness of the entire reflective film structure.

3. A novel dual-band liquid crystal reflective film for automobiles according to claim 1, wherein: The coating solution in S2 includes preparing a mixed solution, which includes: epoxy liquid crystal molecules, one or more of liquid crystal compounds 1, 2, 3, and 4; chiral dopants, such as any two of chiral dopants 1, 2, 3, and 4; chiral dopants with different end groups, such as chiral dopant 1, chiral dopant 2, chiral dopant 3, and chiral dopant 4, etc. Adjust the relative positions of the two reflection spectral bands by adjusting their relative contents and overall contents. Determine the types and proportions of photoinitiators, photoinitiator assistants, and free radical photoinitiators; select solvents, with the mass ratio of cyclopentanone to cyclohexanone being 4:1, or the mass ratio of cyclohexanone to ethyl acetate being 4:1, and mix the above components in a certain proportion to prepare a mixed solution.

4. A novel dual-band liquid crystal reflective film for automobiles as claimed in claim 1, wherein: In step S3, first evenly coat the mixed solution on the substrate, heat and volatilize the substrate coated with the mixed solution at 90-120°C to remove the solvent, irradiate the heated and volatilized substrate with a high-pressure mercury lamp for 10-20 s to initiate a photocrosslinking polymerization reaction to form a polymer thin film material, and irradiate the polymer thin film material with ultraviolet light of 365 nm at 80-130°C.

5. A novel dual-band liquid crystal reflective film for automobiles according to claim 1, characterized in that: In step S3, two drying processes are required. The first drying: Heat and volatilize the coated substrate at 90-120°C to remove the solvent, which is carried out in an oven for 8-16 minutes. The second drying: Irradiate the substrate after photocrosslinking polymerization with ultraviolet light of 365 nm at 80-130°C. This process is carried out in an ultraviolet curing box and usually takes 35 seconds to 3 minutes.

6. A novel dual-band liquid crystal reflection film for automobiles as described in claim 1, characterized in that: In step S3, dual curing is performed, including photocuring and thermal curing. The photocuring: Irradiate the heated and volatilized substrate with a high-pressure mercury lamp for 10-20 s to initiate a photocrosslinking polymerization reaction to form a polymer thin film material; the thermal curing: Irradiate the substrate after photocuring with ultraviolet light of 365 nm at 80-130°C to obtain a double-layer liquid crystal thin film.

7. A novel dual-band liquid crystal reflection film for automobiles according to claim 1, characterized in that: In step S1, the liquid crystal molecules include epoxy liquid crystal molecules such as liquid crystal compound 1, liquid crystal compound 2, liquid crystal compound 3, liquid crystal compound 4, etc., and acrylic liquid crystal molecules of the general formula.

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