A polyimide-doped silver nanowire polarizer and its preparation method

Abstract

This invention relates to a polyimide-doped silver nanowire polarizer and its preparation method, comprising: providing a polyimide solution-dispersed silver nanowire ink; starting a casting machine, coating the polyimide solution-dispersed silver nanowire ink onto a stainless steel strip of the casting machine, and drying it at a first temperature to obtain a polyimide-doped silver nanowire cast film; placing the polyimide-doped silver nanowire cast film in a heating and stretching device, and unidirectionally stretching it to 2-4 times its original size at a second temperature to obtain a polyimide-doped silver nanowire stretched film; placing the polyimide-doped silver nanowire stretched film in a tunnel-type imidization baking oven, and baking and curing it at a third temperature before winding it up to obtain a polyimide-doped silver nanowire polarizer. This method not only achieves large-area thin-film and ultra-thin production of metal wire grid polarizers, but also enables the use of thin-film polarizers in high-temperature polarizing devices. The process is simple and easy to industrialize.

Description

Technical Field

[0001] This invention relates to the field of polarizer technology, and more particularly to a polyimide-doped silver nanowire polarizer and its preparation method. Background Technology

[0002] Polarizers are optical functional thin-film materials. Iodine-based polarizers, which have been industrialized, are widely known for their extensive use in liquid crystal displays and polarized glasses. These polarizers have a semi-transparent blackish-gray appearance; when natural light is incident, half of the light is transmitted and the other half is absorbed. However, these polarizers only function as polarizers in the visible light band. Although metal wire-grid polarizers have special applications in instruments in the infrared, microwave, and terahertz bands, they cannot yet be mass-produced into thin films and are expensive. This makes the manufacturing cost of devices requiring metal wire-grid polarizers outside the visible light band very high.

[0003] However, no high-temperature resistant metal wire grid film polarizer has been prepared in the current technology. Common ordinary polarizers cannot achieve the use of thin film polarizers in high-temperature polarizing devices. Therefore, it is an urgent problem to be solved to prepare a silver nanowire polarizer that can not only achieve large-area thin film and ultra-thin metal wire grid polarizers, but also be able to be used under high temperature conditions. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a polyimide-doped silver nanowire polarizer and its preparation method, so as to prepare a thin film and ultrathin film capable of realizing large area of ​​metal wire grid polarizer, and also to make thin film polarizers available for high temperature polarizing devices.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a polyimide-doped silver nanowire polarizer includes:

[0007] Provides polyimide solution-dispersed silver nanowire ink;

[0008] Start the casting machine, and directionally coat the polyimide solution-dispersed silver nanowire ink onto the stainless steel belt of the casting machine. Then, dry it at the first temperature to obtain a polyimide-doped silver nanowire casting film.

[0009] The polyimide-doped silver nanowire cast film is placed in a heating and stretching device and unidirectionally stretched to 2-4 times at a second temperature to obtain a polyimide-doped silver nanowire stretched film.

[0010] A polyimide-doped silver nanowire stretched film was placed in a tunnel-type imidization baking oven, baked and cured at a third temperature, and then wound up to obtain a polyimide-doped silver nanowire polarizer.

[0011] As a preferred technical solution, in the silver nanowire dispersible ink in polyimide solution, the silver nanowire content is 0.5-5 wt%, and the polyimide content is 15-25 wt%.

[0012] As a preferred technical solution, the silver nanowires have a diameter of 10-100 nm and a length of 0.5-50 μm.

[0013] As a preferred technical solution, a slit coating head is used to coat polyimide solution-dispersed silver nanowire ink onto a stainless steel belt of a casting machine, thereby forming a stable liquid layer of polyimide solution-dispersed silver nanowire ink on the stainless steel belt.

[0014] The silver nanowires are oriented roughly along the transmission direction of the stainless steel strip.

[0015] As a preferred technical solution, the thickness of the liquid layer is 0.2mm-0.4mm.

[0016] As a preferred technical solution, polyimide solution-dispersed silver nanowire ink is coated onto a stainless steel belt of a casting machine and dried at a first temperature to obtain a polyimide-doped silver nanowire cast film, comprising:

[0017] The first temperature is 90-120℃; the thickness of the polyimide-doped silver nanowire cast film is 40-160μm.

[0018] As a preferred technical solution, a polyimide-doped silver nanowire cast film is placed in a heating and stretching apparatus and unidirectionally stretched to 2-4 times its original size at a second temperature to obtain a polyimide-doped silver nanowire stretched film, comprising:

[0019] The polyimide-doped silver nanowire cast film was stretched along the orientation direction of the silver nanowires.

[0020] As a preferred technical solution, the second temperature is 150–180°C; the thickness of the polyimide-doped silver nanowire stretched film is 20–80 μm.

[0021] As a preferred technical solution, the polyimide-doped silver nanowire stretching film is baked at the third temperature for at least 60 minutes, and the thickness of the polyimide-doped silver nanowire polarizer obtained after curing is 20-80 μm.

[0022] Preferably, the third temperature is 220-360℃.

[0023] This application also provides a polyimide-doped silver nanowire polarizer, prepared by any of the methods described above.

[0024] The beneficial effects achieved by the technical solution adopted in this invention are as follows: This specification combines high-temperature resistant polyimide thin film material with silver nanowires to manufacture a high-temperature resistant polyimide-doped silver nanowire polarizer. This not only enables the large-area thin film and ultra-thin design of metal wire grid polarizers, but more importantly, it solves the problem of having thin film polarizers available for high-temperature polarizing devices. This manufacturing method is simple and easy to industrialize. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a flowchart illustrating the preparation method of the polyimide-doped silver nanowire polarizer disclosed in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Example

[0031] according to Figure 1 This embodiment proposes a method for preparing a polyimide-doped silver nanowire polarizer, comprising:

[0032] Step 101: Provide a polyimide solution to disperse silver nanowire ink.

[0033] Step 102: Start the casting machine, coat the polyimide solution-dispersed silver nanowire ink onto the stainless steel belt of the casting machine, and dry it at the first temperature to obtain a polyimide-doped silver nanowire casting film.

[0034] Step 103: Place the polyimide-doped silver nanowire cast film in a heating and stretching device and stretch it unidirectionally to 2-4 times at a second temperature to obtain a polyimide-doped silver nanowire stretched film.

[0035] Step 104: Place the polyimide-doped silver nanowire stretched film in a tunnel imidization oven, bake and cure it at the third temperature, and then roll it up to obtain a polyimide-doped silver nanowire polarizer.

[0036] Since existing metal wire grid polarizers cannot be produced in large-area thin films and ultra-thin films, and there are no thin-film polarizers available for high-temperature polarizing devices, this embodiment proposes a method for preparing polyimide-doped silver nanowire polarizers. First, silver nanowire ink is dispersed in a polyimide solution, then coated onto a stainless steel strip in a casting machine. After drying, a soft film is obtained. This soft film is then stretched on a multi-roll hot-rolling unidirectional stretching machine. Finally, the stretched film is cured in a high-temperature imidization furnace, thus producing the polyimide-doped silver nanowire polarizer. The silver nanowire polarizer prepared by this method not only possesses the polarizing effect of metal wire grid polarizers in all visible and non-visible light bands, but also has the characteristics of large-area thin-film production and ultra-thin production. Most importantly, because this method mainly uses polyimide, which has excellent high-temperature resistance, the polarizer prepared using it exhibits strong high-temperature resistance. The polarizers prepared in this embodiment are produced using coating machines, casting machines, and thermal stretching machines commonly used in the plastic film manufacturing industry.

[0037] In one embodiment of this specification, step 101 specifically includes:

[0038] In polyimide solution-dispersed silver nanowire ink, the silver nanowire content is 0.5-5 wt%, and the polyimide content is 15-25 wt%.

[0039] In a preferred embodiment, a manufacturer directly provides silver nanowire ink dispersed in a polyimide solution, wherein the ink contains 1 wt% silver nanowires, 24 wt% polyimide, and the remainder is a volatile solvent from the polyimide mother liquor. In another preferred embodiment, the silver nanowires have a diameter of 10-100 nm and a length of 0.5-50 μm.

[0040] Alternatively, those skilled in the art can prepare polyimide solution-dispersed silver nanowire ink according to actual needs. This ink is mainly prepared by mixing polyimide solution and silver nanowires. The polyimide solution includes a polyamic acid precursor and a soluble polyimide solvent. The solvent includes, but is not limited to, all existing solvents that can dissolve polyamic acid precursors, and is not limited here. The specific preparation process of polyimide solution-dispersed silver nanowire ink adopts existing preparation methods and will not be described in detail here.

[0041] In one embodiment of this specification, step 102 specifically includes:

[0042] Using a slit coating head, polyimide solution dispersed silver nanowire ink is directionally coated onto a stainless steel belt of a casting machine, forming a stable liquid layer on the stainless steel belt.

[0043] The silver nanowires are oriented roughly along the transmission direction of the stainless steel strip.

[0044] Specifically, on a casting machine, polyimide solution-dispersed silver nanowire ink is placed on a coating machine. The ink is extruded from a slit-type coating head and directionally coated onto the stainless steel belt of the casting machine. Because the polyimide solution-dispersed silver nanowire ink has a certain agglomeration force, resembling a state between solid and liquid, a stable liquid layer is formed with a thickness of 0.2 mm to 0.4 mm. In a preferred embodiment, the liquid film thickness is 0.32 mm. Since the thickness of the liquid layer further affects the size of the subsequently produced polarizer, the thickness of the liquid layer can be selected by those skilled in the art according to actual needs, and is not specifically limited here.

[0045] The specific thickness and width of the liquid film layer can also be set by those skilled in the art according to actual needs.

[0046] In practice, when dispersing silver nanowire ink in polyimide solution through a slit coating head, it is important to maintain a consistent pressure and directional extrusion to ensure that the silver nanowires are oriented approximately along the stainless steel belt transport direction.

[0047] Step 102 specifically includes: the first temperature is 90-120℃; the thickness of the polyimide-doped silver nanowire cast film is 40-160μm.

[0048] In a preferred embodiment, the stainless steel belt of the casting machine is set to a low speed, the heating temperature is set to 90°C, and the liquid film travels on the stainless steel belt of the casting machine for 60 minutes. A polyimide-doped silver nanowire cast film with a thickness of 80 μm and a width of 60 cm is produced using the casting machine, wherein the silver nanowires in the cast film are initially oriented approximately along the extrusion direction.

[0049] In one embodiment of this specification, step 103 specifically includes:

[0050] The polyimide-doped silver nanowire cast film was stretched along the orientation direction of the silver nanowires.

[0051] Specifically, on a multi-roller hot stretching machine, the polyimide-doped silver nanowire cast film is heated and then stretched unidirectionally with a stretching ratio of 2-4 times. This not only ensures that the polyimide-doped silver nanowire cast film will not break, but also ensures that the prepared polarizer not only has the function of a metal grid polarizer, but also has the characteristics of high temperature resistance.

[0052] Step 103 further includes: the second temperature is 150-180℃; the thickness of the polyimide-doped silver nanowire stretched film is 20-80μm.

[0053] Specifically, the heating temperature implemented on the multi-roll thermal stretching machine is controlled below the polyimide curing temperature. In a preferred embodiment, the second temperature is 160°C, and the stretching direction is along the initial orientation direction of the silver nanowires, with a stretching ratio of 4 times. This stretching process produces a polyimide-doped silver nanowire stretched film with a thickness of 40 μm and a width of 30 cm. The thermal stretching process amplifies the anisotropy, causing the silver nanowires to be roughly parallel and aligned along the stretching direction, thereby enabling the polyimide-doped silver nanowire stretched film to function as a metal wire grid polarizer.

[0054] In one embodiment of this specification, step 104 specifically includes:

[0055] The polyimide-doped silver nanowire stretched film is baked at the third temperature for at least 60 minutes, and the thickness of the polyimide-doped silver nanowire polarizer obtained after curing is 20-80 μm.

[0056] Specifically, the polyimide-doped silver nanowire stretched film is placed in an imidization furnace and baked and cured. In a preferred embodiment, the baking temperature is 220-360°C and the baking time is 60 minutes. After high-temperature imidization, a polyimide-doped silver nanowire polarizer with a thickness of 20-80 μm is obtained, and finally it is wound up by a winding machine.

[0057] This embodiment also provides a polyimide-doped silver nanowire polarizer, which is prepared by the above method.

[0058] Polyimide-doped silver nanowire polarizers are highly practical, possessing both the optical properties of metal wire grid polarizers and enabling large-area thin-film and ultra-thin production of metal wire grid polarizers. This makes it possible for metal nanowire polarizers to be used in polarization devices across multiple wavelengths, including visible and non-visible light, while significantly reducing the manufacturing cost of related devices. Furthermore, due to the high-temperature resistance of polyimide materials, they have promising application prospects in high-temperature devices.

[0059] The above provides a detailed description of a polyimide-doped silver nanowire polarizer and its preparation method according to embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a polyimide-doped silver nanowire polarizer, characterized in that, include: A polyimide solution-dispersed silver nanowire ink is provided, the ink comprising a polyimide solution and silver nanowires, wherein the polyimide solution comprises a polyamic acid precursor and a soluble polyimide solvent; Start the casting machine, coat the polyimide solution-dispersed silver nanowire ink onto the stainless steel belt of the casting machine, and dry it at a first temperature to obtain a polyimide-doped silver nanowire casting film. The polyimide-doped silver nanowire cast film is placed in a heating and stretching device and unidirectionally stretched to 2-4 times at a second temperature to obtain a polyimide-doped silver nanowire stretched film. The polyimide-doped silver nanowire stretch film was placed in a tunnel imidization baking oven, baked and cured at a third temperature, and then wound up to obtain a polyimide-doped silver nanowire polarizer. In the polyimide solution-dispersed silver nanowire ink, the silver nanowire content is 0.5-5 wt%, and the polyimide content is 15-25 wt%.

2. The method according to claim 1, characterized in that, The silver nanowires have a diameter of 10-100 nm and a length of 0.5-50 μm.

3. The method according to claim 1, characterized in that, The casting machine is started, and the polyimide solution-dispersed silver nanowire ink is coated onto the stainless steel belt of the casting machine, including: Using a slit coating head, the polyimide solution-dispersed silver nanowire ink is directionally coated onto the stainless steel belt of the casting machine, and the polyimide solution-dispersed silver nanowire ink forms a stable liquid layer on the stainless steel belt. The silver nanowires are oriented approximately along the transmission direction of the stainless steel strip.

4. The method according to claim 3, characterized in that, The thickness of the liquid layer is 0.2mm-0.4mm.

5. The method according to claim 1, characterized in that, The casting machine is started, and the polyimide solution-dispersed silver nanowire ink is coated onto the stainless steel belt of the casting machine. The coating is then dried at a first temperature to obtain a polyimide-doped silver nanowire cast film, comprising: The first temperature is 90-120℃; the thickness of the polyimide-doped silver nanowire cast film is 40-160μm.

6. The method according to claim 1, characterized in that, The polyimide-doped silver nanowire cast film is placed in a heating and stretching apparatus and unidirectionally stretched to 2-4 times its original size at a second temperature to obtain a polyimide-doped silver nanowire stretched film, comprising: The polyimide-doped silver nanowire cast film is stretched along the orientation direction of the silver nanowires.

7. The method according to claim 6, characterized in that, The second temperature is 150~180℃; the thickness of the polyimide-doped silver nanowire stretched film is 20~80mm.

8. The method according to claim 1, characterized in that, The polyimide-doped silver nanowire stretched film is placed in a tunnel-type imidization oven and baked and cured at a third temperature before being wound up to obtain a polyimide-doped silver nanowire polarizer, comprising: The polyimide-doped silver nanowire stretched film is baked at the third temperature for at least 60 minutes, and the thickness of the polyimide-doped silver nanowire polarizer obtained after curing is 20~80 mm.

9. The method according to claim 1, characterized in that, The third temperature is 220-360℃.

10. A polyimide-doped silver nanowire polarizer, prepared by the method described in any one of claims 1-9.

Images