KR102028209B1 - Carbon nanotube Polarizer and Fabricating Method of the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a polarizing film, and to produce a polarizing film by polymerizing carbon nanotube clusters aligned and elongated using an electric or magnetic field in a polymerizable liquid crystal composition mixed with carbon nanotube clusters in a simple process. It is about a method.

Description

Carbon nanotube polarizing film manufacturing method and carbon nanotube polarizing film by the same {Carbon nanotube Polarizer and Fabricating Method of the same}

The present invention relates to a method for producing a carbon nanotube polarizing film, and applying an electric or magnetic field to a composition in which a carbon nanotube cluster and a polymerizable material are mixed, and carbon nanotube polarization film-forming a stretched and aligned carbon nanotube cluster. A method for producing a film.

Recently, liquid crystal displays, which have the upper hand in flat panel displays, are under great threat in the display market due to the rapid growth of organic light emitting displays. Accordingly, the required image quality characteristics are also increasing, and researches for improving the characteristics of the conventional liquid crystal mode, the backlight, and the polarizing plate have been conducted in order to satisfy these requirements. The polarizing film is a mechanism having a function of transmitting and shielding light, and in the LCD, the polarizing film is a basic component because it functions to switch light. In addition to the LCD, the polarizing film is applied to small devices such as electronic calculators and wristwatches in the early stages of development, and recently, laptop personal computers, word processes, liquid crystal color projectors, vehicle navigation systems, liquid crystal televisions, personal phones, and indoor and outdoor measurements. It is extensive in apparatus.

Conventional polarizing film is manufactured with a structure comprising a polyvinyl alcohol (PVA) film polarizer dyed with iodine or dichroic dye and a protective film on one or both sides.

However, since the polarizing plate uses a method of attaching a product in the form of a film to the outside of the liquid crystal device, it is difficult to control the process and causes a defect, thereby lowering the production yield and inevitably increasing the cost. In addition, the conventional attachment type polarizing plate has a disadvantage that the intensity of the polarized light is fixed in a manner that is produced by stretching the film.

Korean Patent Laid-Open Publication No. 2006-0092737 relates to a film composed of carbon nanotubes and a method of manufacturing the same, which provides a carbon nanotube film having optical transparency in the visible light region, or a chemically treated carbon nanotube or A carbon nanotube bundle is deposited on a substrate using a Langmuir-Blodgett method to disclose a uniform or patterned carbon nanotube film and a method of manufacturing the same. The patent document describes that carbon nanotubes prepared by the above method are extremely thin and uniform enough to have conductivity and transparent, and can be used in electronic devices, sensors, displays, etc. because the carbon nanotubes are oriented in one direction at a high density. have. However, the technology has a disadvantage in that it is not possible to commercially produce small scale in a very limited place as well as the durability of the film is weak, so it is difficult to secure reliability as a material.

On the other hand, the researchers of the present invention for the first time in the world announces the property that when the electric field is applied to the carbon nanotubes dispersed in the liquid crystal in the form of clusters, the cluster of carbon nanotubes is stretched (stretched) four times or more, and restored for the first time when the electric field is off. Nano Letters August issue).

The present invention intends to apply the electrical properties of the newly identified carbon nanotubes to the production of a polarizing film.

It is an object of the present invention to provide a method for producing a polarizing film having a polymerizable composition layer in which carbon nanotube clusters are aligned and stretched only by a simplified process using an electric or magnetic field.

In order to achieve the above object, the present invention

Mixing and applying a carbon nanotube cluster and a polymerizable material onto a substrate;

Stretching the carbon nanotube clusters in a predetermined direction by providing an electric or magnetic field to the substrate to which the mixture is applied; And

It relates to a method for producing a carbon nanotube polarizing film comprising the step of providing heat or light to cure the polymerizable material.

In another aspect, the present invention is a carbon nanotube polarizing film prepared by the above method, wherein the polarizing film is a carbon nanotube comprising a carbon nanotube cluster fixed to the binder is stretched in one direction with a binder cured polymerizable material It relates to a polarizing film.

In another aspect, the present invention relates to a liquid crystal display device in which the carbon nanotube polarizing film is coated on or inside the liquid crystal display device.

The present invention can solve problems such as defective rate caused by dust or the like caused by mounting a polarizing plate of the film type using a conventional adhesive because it is mounted on the inside or outside of the liquid crystal display.

In addition, the present invention, unlike the conventional stretch type polarizing plate can control the polarization of light by using an electric field or magnetic field, it is possible to implement a very fast process speed, it is possible to build a more simplified process line and thus the cost is reduced have.

In addition, since the polarizing material of the present invention is an inorganic material, compared with the conventional polarizing plate, the temperature limitability is improved to 150 ° C. or more, thereby providing a polarizing plate capable of expanding the operating temperature range of the display.

The polarizing film manufacturing method of the present invention can change the transmittance or intensity of polarized light by adjusting the length (width) of the carbon nanotube cluster by the intensity of the electric field.

Therefore, broad commercialization is expected in the future.

1 is a schematic diagram of an apparatus for forming a polarizing film using a polymerizable liquid crystal composition mixed with carbon nanotube clusters aligned and elongated by an electric field according to a first embodiment of the present invention.
2 shows a schematic diagram of an electric field generating apparatus according to the first embodiment of the present invention when the substrate is in the form of a sheet.
FIG. 3 illustrates an electric field distribution diagram generated when voltage is alternately applied in the electric field generator of FIG. 2.
Figure 4 shows a schematic diagram of a polarizing film manufacturing process when the substrate is a sheet (sheet) form.
Figure 5 shows a schematic view of the completed polarizing film.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein and the experimental methods described below are well known and commonly used in the art.

In accordance with one aspect of the present invention, a method of manufacturing a carbon nanotube polarizing film of the present invention includes the steps of applying a mixture of carbon nanotube clusters and a polymerizable material on a substrate; Stretching the carbon nanotube clusters in a predetermined direction by providing an electric or magnetic field to the substrate to which the mixture is applied; And providing heat or light to cure the polymerizable material.

First, the present invention is applied by mixing a carbon nanotube cluster and a polymerizable material on a substrate.

The polymerizable material may be a polymer that is cured by heat or ultraviolet rays or a monomer thereof. More specifically, the polymerizable material is triacetyl cellulose (TAC), polyacryl group, polyolefine (PO), polycarbonate (PC), polyethylene telephthalate (PET) ), Polypropylene (PP), polyethylene (PE, PE) and may be selected from monomers thereof.

In the present invention, the polymerizable material may be a polymerizable liquid crystal material. The polymerizable liquid crystal material is a liquid crystalline monomer having a polymerizable group by irradiation with light such as heat or ultraviolet rays. Unlike a liquid crystal whose phase changes with temperature, the polymerizable liquid crystal material is polymerized once and becomes a solid phase. Phase change no longer occurs and refers to a material mainly used in optical films. For example, the liquid crystalline monomer having a polymerizable group exhibits a liquid crystal phase including a mesogen group capable of exhibiting liquid crystallinity and a terminal group capable of photopolymerization, and may be a monomer molecule capable of photopolymerization by a photoinitiator reacting with ultraviolet rays. Can be. The mesogen may be a calamitic mesogen expressing a nematic liquid crystal phase or a discotic mesogen in a dish form capable of expressing a discotic liquid crystal phase. As the polymerizable end group, an acryl group, methacrylic group, vinyl ether group, or epoxide group which are easily radical polymerized may be used. The liquid crystalline monomer may be used in combination with a polymerizable mesogen compound having two or more polymerizable functional groups such as monoreactive to direactive and / or nonpolar to polar compounds to increase crosslinking of the polymer, The alignment profile can also be changed by changing their composition ratio.

The liquid crystalline monomers include RM257, EHA, RMS-013C, and the like.

Trimethylopropane triacrylate may be used as the photoinitiator.

The mixture refers to a composition in which carbon nanotubes are mixed with the polymerizable material or the polymerizable liquid crystal material as the polymerizable composition. For example, the polymerizable composition may include carbon nanotubes and a solvent in the polymerizable material. In addition, the polymerizable composition may include carbon nanotubes and a solvent in the polymerizable liquid crystal material. The solvent is removed during the curing process.

Carbon nanotubes that can be used in the present invention is a single-walled carbon nanotube SWCNT (Single-Walled Carbon Nano Tube), double-walled carbon nanotube DWCNT (Double-Walled Carbon Nano Tube), thin-walled multi-walled carbon nanotube tMWCNT (thin Multi Walled) Carbon Nano Tube) and MWCNT (Multi Walled Carbon Nano Tube) can be used.

Carbon nanotubes have good elasticity and have good bending characteristics, but the carbon nanotubes are less than 10% stretched with voltage. However, carbon nanotubes are the polymerizable When present as a cluster form to the liquid crystal composition electroactive constant (electroactive constant) is 70 (V / um) ^- are carbon nanotubes with ^one or more clusters may be more than four times longer.

In the present invention, it is intended to apply to the polarizing film by using the electrical properties of the carbon nanotube cluster.

The carbon nanotube cluster may be formed by dispersing the carbon nanotube in the polymerizable (liquid crystal) composition. When a small amount of carbon nanotubes are dispersed in the polymerizable composition, the polymerizable (liquid crystal) composition, for example, the liquid crystal molecules are fixed to the surface of the carbon nanotubes by electrostatic attraction, and the interaction between the carbon nanotubes (electrostatic attraction) However, as the content of carbon nanotubes increases, the interaction between them increases, making dispersion difficult and further, agglomeration between carbon nanotubes occurs.

The term carbon nanotube cluster used in the present invention refers to an aggregate in which carbon nanotubes are aggregated and bundled together by an attractive force of each other.

The term "stretching" used in the present invention refers to a phenomenon in which carbon nanotube clusters, which are aggregated and bundled together when the electric field is applied to the carbon nanotube clusters, are loosened in the electric field direction and stretched thin and elongated.

The carbon nanotube cluster may be a dispersion of 1 to 50 wt%, preferably 1 to 10 wt%, more preferably 1 to 5wt% of the carbon nanotubes in a polymerizable (liquid crystal) composition. When the carbon nanotubes are less than 1 wt%, clusters may be formed in the polymerizable (liquid crystal) composition, but may not be used for the polarizing film of the present invention.

This is because the content of the carbon nanotube cluster should be 1wt% or more in order to block all incident light.

In addition, when the carbon nanotube cluster is more than 50wt%, some regions may be aligned and stretched when the voltage is applied to the carbon nanotube clusters, but there is a problem that the alignment and stretching are not performed.

The polymerizable composition may include 0.001 to 5 parts by weight of a photoinitiator based on 100 parts by weight of the polymerizable material or the polymerizable liquid crystal material. A photoinitiator is a substance that absorbs energy from ultraviolet rays and starts a polymerization reaction. Although it varies depending on the type, the photoinitiator plays a role of initiating photopolymerization in which the monomer, oligomer, and free group add energy required for photopolymerization to be converted into a polymer material after curing by containing the amount of the above weight parts. The mixing ratio of the photoinitiator shows a lot of difference depending on the application and the equipment. Generally, the mixing ratio is about 0.1 to 5%.

Next, the present invention includes the step of stretching the carbon nanotube clusters in a predetermined direction by providing an electric or magnetic field to the substrate coated with the mixture.

In the present invention, the carbon nanotube cluster mixed with the polymerizable material is aligned and stretched using an electric or magnetic field.

1 is a schematic diagram of an apparatus for forming a polarizing film using a polymerizable composition mixed with carbon nanotube clusters aligned and stretched by an electric field according to a first embodiment of the present invention.

As shown in FIG. 1, an electric field generating apparatus 100 is installed on an upper portion of the substrate 300 on which the polymerizable composition 200 in which carbon nanotube clusters are mixed is applied, and horizontally in the polymerizable composition in which carbon nanotube clusters are mixed. An electric field can be applied. In this case, the carbon nanotubes may be stretched by aligning the carbon nanotube clusters controlled to a certain size by a horizontal electric field above the threshold voltage in one direction and applying a horizontal electric field higher than the applied voltage.

The transmittance of light may be controlled by the intensity of the electric or magnetic field applied to the polymerizable composition. The strength of the applied electric field or magnetic field may be greater than or equal to the threshold electrode field of the carbon nanotube cluster and less than the breaking electric field, and preferably greater than the threshold electric field or less than the maximum electric field.

In the present invention, a term used in the present invention refers to an electric field in which a cluster of clusters starts to increase when a voltage is applied to the carbon nanotube cluster in a fluid. The breaking electric field represents an electric field in which carbon nanotube clusters are increased at a constant rate as the voltage is continuously increased, but at some point, the carbon nanotube clusters are broken down.

The maximum electric field is an electric field in which the length of the carbon nanotube cluster is maximum. The maximum electric field exhibits a lower value than the breaking electric field, that is, the cluster is no longer stretched even after the maximum electric field is applied, and the carbon nanotube cluster is destroyed when it is raised to the breaking electric field.

The threshold electric field, the breaking electric field and the maximum electric field may have different values depending on the type, content and type of the polymerizable material of the carbon nanotubes. For example, in the case of a carbon nanotube cluster formed by dispersing a double-walled carbon nanotube in a polymerizable liquid crystal material at a concentration of 1 wt%, the threshold electric field may be about 1.5 V / μm, and the maximum electric field may be about 6 V / μm.

In the polarizing film manufactured according to the present invention, the transmittance of light becomes maximum when the intensity of the applied electric field is near the maximum electric field or the breaking electric field, and almost no light is transmitted through the threshold electric field. That is, by adjusting the length (width) of the carbon nanotube cluster by the intensity of the electric field can be changed the transmittance or intensity of the polarized light.

On the other hand, since the applied horizontal electric field is a force field formed by the distribution and movement of + charges and-charges, there is only a difference in the properties of fluxes that determine the direction and the intensity of the field, and is almost similar. Although the embodiments and drawings of the present invention have been described with reference to electric fields, since electric and magnetic fields are generated in mutually orthogonal directions, and have similar properties, the application of the examples and description of electric fields to magnetic fields is a polymerizable composition. It will be apparent to those skilled in the art in view of the fact that the orientation direction of is formed in the orthogonal direction compared to the electric field in the case of the magnetic field.

The method of manufacturing a polarizing film according to the present invention may be applied to a roll-to-roll process, and in this case, the substrate may be characterized as having a long film form. The long film form means a continuous film having a constant width, and means a continuous film that can be supplied in a rolled form. Film is continuous in roll-to-roll process

Because of their movement, it can be said that a constant electric or magnetic field is applied to the entire film regardless of the intensity distribution of the electric or magnetic field.

When the manufacturing method of the polarizing film according to the present invention is applied to a sheet-like substrate, a portion directly above the electrode or the magnet of the electric field or the magnetic field generator does not generate the electric field or the magnetic field. Therefore, when the substrate is in the form of a sheet, it is preferable that the generators of the electric or magnetic fields are alternately connected.

2 shows a schematic diagram of an electric field generating apparatus according to the first embodiment of the present invention when the substrate is in the form of a sheet. When the electrodes of the electric field generating device are alternately connected as shown in FIG. 2, the carbon nanotube clusters corresponding to the portions in which the electric field is not generated directly on the electrode 102 are aligned and elongated to polymerize the polymerizable liquid crystal composition to form a film. can do.

FIG. 3 is an electric field distribution diagram generated when voltage is alternately applied in the electric field generator of FIG. 2. As shown in FIG. 3, the horizontal electric field 400 generated when the voltage is alternately applied to the electric field generator of FIG. 2 is a substrate coated with a polymerizable liquid crystal composition in which carbon nanotube clusters located under the electric field generator are mixed. It is evenly distributed over the entire area, so that carbon nanotube clusters can be aligned and stretched in the whole area.

An apparatus for generating an electric or magnetic field may be located above or below the substrate.

Next, the present invention includes a curing step. The curing step is to provide heat or light to the mixture to cure the polymerizable material. By the curing step, the polymer material is cured while polymer polymerization occurs. The polymerizable material is cured to form a binder of the film, and carbon nanotube clusters are fixed by the binder to maintain an elongated state.

Figure 4 shows a schematic view of the manufacturing process of the polarizing film when the substrate (sheet) form. The electric field generating device is manufactured by forming a pattern electrode on a substrate. In addition, a polymerizable liquid crystal composition in which carbon nanotubes are mixed is coated on a substrate for a polarizing film. The electric field generating device is positioned above or below the substrate on which the polymerizable liquid crystal composition containing carbon nanotubes is applied, and then horizontal electric fields are alternately applied to align and stretch the carbon nanotube clusters mixed in the polymerizable liquid crystal composition. . The polarizing film is prepared by curing ultraviolet ray irradiation or heat to the polymerizable liquid crystal composition layer in which carbon nanotube clusters are mixed by uniformly aligning and stretching the carbon nanotube clusters in all regions.

Figure 5 shows a schematic view of the completed polarizing film. As shown in FIG. 5, the carbon nanotube clusters are evenly aligned and stretched in all regions in one direction by an applied horizontal electric field, and the polymerizable liquid crystal composition is polymerized to arrange and stretch tannonanotube clusters in one direction. Fixed and filmed.

Substrate usable in the present invention is preferably a substrate having an optical transparency of more than 85%, polyether sulfone (PES), polyimide (PI), cyclo olefin polymer (COP), polyethylene terephthalate (PET), triacetyl cellulose (TAC), It may be characterized in that it is selected from the group consisting of PC (poly carbonate) and glass. The limited materials are materials generally available in the art, and are not fixed conditions for materials that can be easily changed and used by those skilled in the art.

In the present invention, the coating of the polymerizable liquid crystal composition in which the carbon nanotube clusters are mixed may include spin, comma, gravure, dip, slot die, and silk screen. It can be carried out by applying a known coating process such as screen, inkjet printing. Curing conditions vary depending on the properties of the polymerizable liquid crystal material.

The carbon nanotube polarizing film prepared according to the present invention includes a carbon nanotube cluster fixed to the binder by curing the polymerizable material to form a binder of the film and extending in one direction.

As described above, the polarizing film may change the transmittance or intensity of polarized light by adjusting the length (width) of the carbon nanotube cluster by the intensity of an electric field or a magnetic field.

In addition, since the polarizing film of the present invention can control the polarization of light by using an electric field or a magnetic field, unlike the conventionally stretched polarizing plate, it is possible to realize a very fast process speed and to further simplify the construction of the process line, thereby reducing costs. It has the advantage of being.

In addition, the polarizing film of the present invention, since the polarizing material is an inorganic material, the temperature limitability is improved to 150 ° C. or more as compared to the conventional polarizing plate, thereby extending the operating temperature range of the display.

The present invention relates to a liquid crystal display device in which the polarizing film is coated inside or outside. Accordingly, the liquid crystal display device of the present invention can prevent the generation of a defective rate due to dust or the like, compared to a film type polarizing plate using a conventional adhesive.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of the present invention will be apparent from the appended claims.

100: electric field generator
101: substrate of the field generator
102: electrode
200: polymerizable composition layer mixed with carbon nanotube clusters
201: Aligned and stretched carbon nanotube clusters
202: polymerized liquid crystal composition
300: substrate of the polymerizable composition layer mixed with carbon nanotube clusters
400: horizontal electric field

Claims (12)

Applying a mixture of carbon nanotube clusters to the substrate on a substrate;
Stretching the carbon nanotube clusters in a predetermined direction by providing an electric or magnetic field to the substrate to which the mixture is applied; And
A method of manufacturing a carbon nanotube polarizing film comprising providing a heat or light to a mixture including an elongated carbon nanotube cluster to cure the polymerizable material.
The carbon nanotube cluster is contained in the mixture in 1 to 50 wt%,
The stretching step is to control the carbon nanotube cluster length by controlling the strength of the electric or magnetic field to less than the breakdown electric field of the threshold electrode field of the carbon nanotube cluster,
The polymerizable material is cured to form a binder of the polarizing film by the curing step, and the carbon nanotube cluster is fixed to the binder to maintain a stretched state of the carbon nanotube polarizing film. The method of claim 1, wherein the polymerizable material is a liquid crystal compound having an acrylic group, a vinyl ether group, or an epoxide functional group. The method of claim 1, wherein the polymerizable material is a polymer cured by heat or ultraviolet rays or a monomer thereof. The method of claim 3, wherein the polymer is triacetyl cellulose (TAC), polyacryl group, polyolefine (PO), polycarbonate (PC), polyethylene telephthalate (PET) ), Polypropylene (PP), polyethylene (Polyethylene, PE) and a method for producing a carbon nanotube polarizing film, characterized in that selected from monomers thereof. The method of claim 1, wherein the device for generating an electric field or a magnetic field is located above or below the substrate. delete The method of claim 1, wherein the substrate is in the form of a long film. The method of claim 1, wherein the substrate is in the form of a sheet. delete The method of claim 1, wherein when the substrate is in the form of a sheet, the generator of the electric field or the magnetic field is alternately connected. The carbon nanotube polarizing film prepared by any one of claims 1 to 5, 7, 8 and 10, wherein the polarizing film is a binder cured polymerizable material, and in one direction A carbon nanotube polarizing film, characterized in that it comprises a carbon nanotube cluster is stretched and fixed to the binder. A liquid crystal display device comprising a carbon nanotube polarizing film prepared by any one of claims 1 to 5, 7, 8 and 10, wherein the polarizing film is inside or outside the liquid crystal display device. Liquid crystal display device characterized in that the coating is formed on.

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