WO2013032160A2

WO2013032160A2 - Method for manufacturing a phase retardation film

Info

Publication number: WO2013032160A2
Application number: PCT/KR2012/006617
Authority: WO
Inventors: 이성규; 최진욱; 김성민; 이승희; 이명훈; 강신웅; 정광운
Original assignee: 주식회사 동진쎄미켐
Priority date: 2011-08-30
Filing date: 2012-08-21
Publication date: 2013-03-07
Also published as: TW201314250A; KR101200965B1; WO2013032160A3

Abstract

The present invention relates to a method for manufacturing a phase retardation film, and more particularly, to a method for manufacturing a phase retardation film in which a polymer liquid crystal composition is oriented using electrical fields or magnetic fields, without forming an alignment layer, so as to manufacture the phase retardation film through a simple process. According to the method for manufacturing the phase retardation film of the present invention, since the polymer liquid crystal composition is oriented using the electrical fields or magnetic fields, a process of forming an alignment material layer is not used and a process of rubbing or optically aligning the alignment material layer may be eliminated, and thus the present invention exhibits the advantages of the manufacturing process being very quickly performed and a process line being more simply constructed to reduce manufacturing costs. Further, while conventionally the number of alignment processes is increased whenever a pattern is added, in the method for manufacturing a phase retardation film of the present invention, only the structure of the electrode need be differently set to form patterns having different shapes, and thus the present invention exhibits the advantage of an additional processes not being required.

Description

Method of manufacturing phase delay film

The present invention relates to a method for manufacturing a phase delay film, and relates to a method for preparing a phase delay film by a simple process by forming an orientation in a polymerizable liquid crystal composition using an electric field or a magnetic field without using an alignment film.

As the information society develops, the demand for display devices is increasing in various forms, and various kinds of flat panel display devices have been developed and used. Among them, the liquid crystal display is a flat panel display which is widely used for various purposes. As such, various technical advances have been made in order to serve as a screen display device in various fields, and the goal is to realize high quality images while maintaining the characteristics of light weight, thinness, and low power consumption. In addition, the liquid crystal display includes a twisted nematic (TN) liquid crystal display, a vertically aligned liquid crystal display (VA), an in-plane switching (IPS) liquid crystal display, and an OCB depending on the arrangement and driving method of the liquid crystal. (Optically Compensated Bend) liquid crystal display. In these liquid crystal display devices, the liquid crystals initially form a predetermined array due to the influence of the alignment layer or the properties of the liquid crystal itself, but when the electric field is applied, the arrangement of the liquid crystals is changed. Due to the optical anisotropy of the liquid crystals, polarization of light passing through the liquid crystals The image is displayed by changing the state depending on the arrangement state of the liquid crystal and making it appear as a difference in the amount of transmitted light using the polarizing plate.

In the birefringent STN-LCD, since the cell itself is birefringent, phase delay (light distortion) occurs in light that has passed through the liquid crystal cell. For this reason, in a STN panel, a phase delay film is used in parallel as a film for color compensation. Phase delay films have been developed as optical compensation for STN-specific interference colors (coloring) called blue mode or yellow mode caused by elliptical polarization. In the case of TFT-LCD, phase film as a color compensation film is unnecessary. However, in recent years, various phase retardation films have been laminated for the purpose of expanding the viewing angle and improving image quality, and a phase retardation film having various functions has been required. In addition, with the development of 3D stereoscopic image reproduction technology, a technology for making polarization directions of left and right eyes different from each other by using a patterned phase delay film has been developed. As the manufacturing technique of the phase delay film, there are a stretching technique and an alignment technique, and in particular, an alignment technique is necessary to consider all of polarization, reflection, refraction, interference, diffraction, and scattering.

The orientation for determining the initial arrangement of the liquid crystal is mainly performed by rubbing the alignment film in a specific direction using a rubbing method. However, since the rubbing method is a mechanical method, it is difficult to precisely control the initial alignment state of the liquid crystal, and it is difficult to have different pretilt angles for each minute region. At this time, in order to orient the alignment film of the substrate to show a different direction for each minute unit region, it is common to perform two alignment steps, but a mask is used for such a step.

That is, in Japanese Patent No. 2650205, first, a rubbing process is performed in one direction, and then the mask is applied in a patterned form, and then the rubbing is performed in a direction opposite to the first rubbing, so that the opened part of the applied mask has a primary alignment portion. It proposes a technology that can be formed in the opposite direction, in this case, after the first rubbing, a resist is applied to the upper alignment layer and irradiated with light to form a pattern to develop a resist exposed in the pattern. Although the upper layer side alignment layer was etched by this developer, the lower layer side alignment layer was exposed, and secondary rubbing was performed to form an alignment layer oriented in a direction different from the primary rubbing, but the process was complicated and a chemical developer There is a problem that the alignment performance of the liquid crystal can be lowered by using a, and finely attached in the process of attaching the mask in a patterned form Groups has the disadvantage that can be difficult.

In addition, in Japanese Patent No. 3596727, in a patterned first region and a second region, the first region is first applied with a mask and the second region is exposed, and then first rubbing is performed and the mask is applied. After removal, a method of manufacturing a patterned phase delay film by providing a birefringent layer and performing a second rubbing has been proposed. However, the boundary line between regions having different processing steps and different orientations in patterning a mask may be unclear. There is a disadvantage.

Moreover, each time an orientation process is added, the process speed is slowed down, which is the biggest cause of the decrease in productivity. This may cause the price of the product to rise.

The present invention proposes a completely new orientation method of the polymerizable liquid crystal composition in order to solve the above problems, and does not require an alignment agent layer when forming the orientation of the polymerizable liquid crystal composition applied on the substrate using an electric or magnetic field. The present invention has been completed, confirming that the process is simplified and costs are reduced and that no additional process or apparatus is required for pattern formation.

Summary of the Invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a phase delay film having a polymerizable liquid crystal composition layer in which alignment is formed by a simplified process without requiring an alignment agent layer.

In order to achieve the above object, the present invention comprises the steps of (a) applying a polymerizable liquid crystal composition on a substrate; (b) providing an electric field or a magnetic field to the substrate to which the polymerizable liquid crystal composition is applied to form an orientation in the polymerizable liquid crystal composition in a predetermined direction; And (c) polymerizing the polymerizable liquid crystal composition by providing heat or light to the polymerizable liquid crystal composition having the alignment property, and a phase retardation film prepared by the method. To provide.

1 is a schematic diagram of an apparatus for forming an orientation in a polymerizable liquid crystal composition by an electric field according to an embodiment of the present invention.

Figure 2 shows a schematic diagram of an electric field generating device according to an embodiment of the present invention.

3 is a schematic diagram of an apparatus for forming an orientation in a polymerizable liquid crystal composition by an electric field according to another embodiment of the present invention.

Figure 4 shows a schematic diagram of the electric field generating device when the substrate is in the form of a sheet (sheet).

Figure 5 shows a schematic view of the phase delay film manufacturing process when the substrate (sheet) form.

Figure 6 shows a POM image confirming the RM orientation according to the electric field strength of the phase delay film prepared according to an embodiment of the present invention.

Figure 7 shows the POM image according to the rotation angle of the substrate by rotating the phase delay film prepared according to an embodiment of the present invention after the electric field orientation.

Detailed Description of the Invention and Specific Embodiments

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.

The present invention in one aspect, the present invention comprises the steps of (a) applying a polymerizable liquid crystal composition on a substrate; (b) providing an electric field or a magnetic field to the substrate to which the polymerizable liquid crystal composition is applied to form an orientation in the polymerizable liquid crystal composition in a predetermined direction; And (c) polymerizing the polymerizable liquid crystal composition by providing heat or light to the polymerizable liquid crystal composition in which the alignment is formed.

In the present invention, the polymerizable liquid crystal composition is a composition containing a liquid crystalline monomer having a polymerizable group by irradiation with light such as heat or ultraviolet rays, and is polymerized once, unlike a liquid crystal whose phase changes with temperature. When it is in a solid phase, a phase change no longer occurs and refers to a composition mainly used in an optical film. Conventionally, in order to form alignment in such a polymerizable liquid crystal composition, an alignment agent layer such as polyimide or the like is formed between the substrate and the polymerizable liquid crystal composition layer to form alignment in advance, thereby forming orientation in the polymerizable liquid crystal composition. Used. However, the present invention does not require the above-described alignment agent layer, and proposes a method of directly forming the alignment property in the polymerizable liquid crystal composition using an electric or magnetic field.

In the present invention, the polymerizable liquid crystal composition may be applied in a mixed state with a solvent on a substrate, and may provide an electric or magnetic field to the substrate on which the polymerizable liquid crystal composition is applied to form alignment in the polymerizable liquid crystal composition. 1 is a schematic diagram of an apparatus for forming an orientation in a polymerizable liquid crystal composition by an electric field according to an embodiment of the present invention. As shown in FIG. 1, an electric field generating device may be installed below the substrate on which the polymerizable liquid crystal composition is applied, and a horizontal electric field may be applied to the polymerizable liquid crystal composition layer. The reason why the electric field generating device is not formed on the same plane on which the polymerizable liquid crystal composition is applied is formed on the lower part of the electric field generator because the gap becomes larger as the coated area of the polymerizable liquid crystal composition becomes wider. This is to overcome the phenomenon of weakening of strength. The polymerizable liquid crystal composition layer is oriented according to the direction of the applied horizontal electric field, and it is possible to adjust the orientation of the polymerizable liquid crystal composition by adjusting the direction of the horizontal electric field using the same. In addition, since electric and magnetic fields are force fields formed by the distribution and movement of + charges and-charges, there is a difference in the properties of fluxes that determine the direction and the intensity of the field, and are almost similar. Although the embodiments and drawings of the present invention have been described based on the electric field, since the electric field and the magnetic field are generated in mutually orthogonal directions, and have similar properties, the embodiment and the description of the electric field are applicable to the magnetic field. It will be apparent to those skilled in the art in view of the fact that the orientation of the composition is in the orthogonal direction relative to the electric field in the case of a magnetic field.

The present invention may be characterized in that the polymerizable liquid crystal composition is formed so as to cross the orientation in different directions at regular intervals, and the polymerizable liquid crystal composition may be formed so as to cross the orthogonality perpendicular to each other at regular intervals. have. Since the alignment direction of the polymerizable liquid crystal composition depends on the direction in which the magnetic field or the electric field is applied, not only the direction of the polymerizable liquid crystal composition can be adjusted by adjusting the direction in which the magnetic field or the electric field is applied, but also the orientation in different directions at regular intervals. Are formed to intersect, and as a result, a polymerizable liquid crystal composition layer having a patterned alignment direction can be formed. Figure 2 shows an example of the electric field generating device according to the present invention. When implementing the zigzag electric field generating device as shown in Figure 2, because the horizontal electric field is applied to the polymerizable liquid crystal composition layer in a zigzag form as a result the polymerizable liquid crystal composition may be formed to cross the orthogonality perpendicular to each other at regular intervals. Can be. Therefore, in order to manufacture a patterned phase retardation film, it is preferable to use an electric or magnetic field generating device having a zigzag shape as shown in FIG. 2.

In another embodiment, the electric or magnetic field generating device may be located on top of the substrate to which the polymerizable liquid crystal composition is applied. When the electric field or the magnetic field generating device is positioned below the substrate to which the polymerizable liquid crystal composition is applied, a phenomenon in which the strength of the electric field or the magnetic field may be weakened by the substrate may cause a problem that the orientation of the polymerizable liquid crystal composition is weakened. have. In order to overcome this, when the electric or magnetic field generating device is positioned on the substrate to which the polymerizable liquid crystal composition is applied, as shown in FIG. 3, the generated electric or magnetic field is not directly affected by the substrate and directly affects the polymerizable liquid crystal composition. This makes it possible to have an effective and precise alignment formation process. When the electric field or the magnetic field generating device is located on the top of the substrate, light irradiation for the polymerization of the polymerizable liquid crystal composition may be performed at the bottom of the substrate, or the light may be emitted from the top of the substrate after the electric or magnetic field generating device is removed. Investigations may be made. In addition, when the electric field or the magnetic field generating device is configured to be transparent, light irradiation can be performed on the upper part of the substrate even when the electric or magnetic field generating device is located on the upper part of the substrate.

As described above, the electric field or the magnetic field generating device may be located on the upper or lower portion of the substrate, by forming an electric or magnetic field generating device on the substrate itself to separate the electric or magnetic field generating device from the outside of the substrate You can avoid the trouble of installing. Forming an electric field or magnetic field generating device on the substrate itself means using a substrate having an electric field or magnetic field generating device formed on the top or bottom surface of the substrate itself before applying the polymerizable liquid crystal composition to the substrate. The generator of the electric or magnetic field should have the same transparent characteristics as the substrate and the polymerizable liquid crystal composition.

In the present invention, when the orientation is formed in the polymerizable liquid crystal composition by an electric field, the electric field is preferably characterized by being about 1.5 V / µm or more, and most preferably about 5.5 V / µm or more. You can do In one embodiment of the present invention, the orientation of the polymerizable liquid crystal composition is applied to the polymerizable liquid crystal composition by applying an electric field of various intensities, and when the polymerizable liquid crystal composition is formed, the orientation is obtained when about 5.5 V / µm is applied. Confirmed that it can.

The method of manufacturing a phase delay 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. In the roll-to-roll process, since the film moves continuously, 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. However, when the method of manufacturing the phase delay film according to the present invention is applied to a sheet-like substrate, there is a problem in that an electric field or a magnetic field is not generated in the portion directly above the electrode or the magnet of the electric field or the magnetic field generator. 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. That is, when the electrodes of the electric field generating device are alternately connected as shown in FIG. 4, the alignment property may be formed in the polymerizable liquid crystal composition corresponding to the portion in which the electric field is not generated directly on the electrodes.

Figure 5 shows a schematic view of the manufacturing process of the phase delay film when the substrate (sheet) form. A patterned electrode is formed on a substrate to manufacture an electric field generator. In addition, a reactive liquid crystal composition is applied onto the substrate for the phase delay film. The electric field generating device is positioned above or below the substrate to which the polymerizable liquid crystal composition is applied, and then a horizontal electric field is alternately applied to form a patterned orientation in the polymerizable liquid crystal composition. The phase delay film is manufactured by irradiating ultraviolet rays to the polymerizable liquid crystal composition layer on which the patterned orientation is formed and curing the polymerizable liquid crystal composition layer.

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.

When the patterned orientation is imparted to the polymerizable liquid crystal composition applied on the substrate, the phase delay film may be completed through a process of irradiating and curing the polymerizable liquid crystal composition with light. The polymerizable liquid crystal composition is cured by ultraviolet rays or the like to form a polymerizable liquid crystal composition layer, and the polymerizable liquid crystal composition layer serves to delay the phase of polarized light. Phase delay film according to the present invention is different in the direction and size of the phase delay according to the patterned portion, it may be configured to alternate phase delay direction / size at regular intervals.

In the present invention, the polymerizable liquid crystal composition is composed of a liquid crystal compound having a polymerizable group, and in particular, may have a functional group of an acryl group, a vinyl ether group or an epoxide, and the composition mixture of the polymerizable liquid crystal composition may be a polymer. In order to increase the crosslinking it is possible to use a mixture of two or more polymerizable functional groups such as polymerizable mesogen compounds having monoreactive to direactive and / or nonpolar to polar compounds, and by varying their compositional ratio profile You can also change

By adjusting the thickness of the polymerizable liquid crystal composition layer, it is possible to adjust the phase delay size, and when the magnitude of the phase delay is λ / 4, linearly polarized light may be changed into circularly polarized light. Λ is a sign indicating a wavelength of light whose phase is to be delayed. The phase retardation of the polymerizable liquid crystal is made by the refractive index of the long axis and the short axis in the molecular structure, and the difference is preferably 0.7 to 3. In addition, since the substrate should be coated, it should be used in a certain amount mixed with the organic solvent. The ratio is preferably 5 to 50%, which is only a ratio for facilitating the coating, and it will be apparent that the ratio is not a fixed value.

In the present invention, the application of the polymerizable liquid crystal composition is spin, comma, gravure, dip, slot die, silk screen, inkjet printing (inkjet) It can be carried out by applying a known coating process such as printing). When the process is carried out by spin coating, the coating is 0.5 to 5 μm thick using a method of firstly rotating at 400 to 1000 rpm for 20 to 25 seconds and rotating at 2500 to 3500 rpm for 30 to 80 seconds. After the coating, the curing process is performed by drying at 60 ° C. for 1 minute and irradiating 20 mW / cm ² of ultraviolet rays for 1 minute. These conditions vary depending on the properties of the polymerizable liquid crystal material.

In the present invention, when the alignment directions patterned at regular intervals are orthogonal to each other, and the polymerizable liquid crystal composition layer is applied and cured to have a λ / 4 phase retardation effect, the prepared patterned phase delay film is linearly polarized. The light can be switched between left and right polarized light. The phase delay film thus prepared is mounted on a panel display that separates the left eye image and the right eye image, and polarized glasses separating the left circular polarization and the right circular polarization can realize 3D stereoscopic images.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1 Confirmation of the Orientation of the Polymerizable Liquid Crystal Composition According to the Intensity of the Electric Field

In the present embodiment, the electric field was applied to the polymerizable liquid crystal composition to determine whether or not the alignment is actually formed.

A transparent indium tin oxide (ITO) electrode having a width of 10 μm and a gap of 20 μm was prepared to prepare a patterned substrate in a lattice form, and the polymerizable liquid crystal composition (RMS-013C, Merck co. After spin coating at 23 rpm for 23 seconds and second spin coating at 3000 rpm for 30 seconds to completely coat the substrate, the solvent was dried at 60 ° C. for 1 minute to allow the solvent to fly.

The degree to which the orientation of the polymerizable liquid crystal composition was formed with respect to the generated electric field by applying a voltage to the substrate was measured. In the measurement, the POM prepared by the light source, the polarizer, the substrate, and the analyzer was measured, and the POM image for each electric field intensity is shown in FIG. 6.

As shown in FIG. 6, the luminance began to change from the moment when the applied electric field was 1.5 V / μm, and when 5.5 V / μm was applied, complete dark was formed to confirm that the polymerizable liquid crystal composition was completely oriented by the electric field. there was.

Example 2 Confirmation of optical axis formation of polymerizable liquid crystal composition oriented by electric field

In order to confirm whether an optical axis was formed in the orientation formed by Example 1, the polymerizable liquid crystal composition oriented by applying an electric field of 5.5 V / μm was subjected to an exposure process at 20 mW / cm ² (at365 nm) for 1 minute to form a polymerizable product. The liquid crystal composition was allowed to be fixed on the substrate.

In order to confirm whether an optical axis exists on the substrate after UV curing, the substrate was rotated to check whether there is a change in the POM image. The POM image according to the rotation angle of the substrate is shown in FIG. 7.

As shown in FIG. 7, the luminance of the POM image is changed according to the angle of the substrate, and the optical axis is surely formed by showing a dark image at 0 degrees and 90 degrees, and a bright image at 45 degrees.

Having described the specific part of the present invention in detail, it is apparent to those skilled in the art that such a specific technology is only a preferred embodiment, thereby not limiting the scope of the present invention. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Explanation of the sign

1 board

2 polymerizable liquid crystal composition layer

3 electrodes

4 Board of electric field generator

5 Electric field generator

6 electric field

Since the method of manufacturing a phase delay film according to the present invention forms an alignment property in the polymerizable liquid crystal composition using an electric field or a magnetic field, there is no process of forming an alignment agent layer, and a process itself of rubbing or photoaligning the alignment agent layer may be omitted. As a result, it is possible to realize very high process speeds, to further simplify the construction of process lines, and thus to reduce costs. In addition, although the number of alignment processes is added every time a pattern is added, the method of manufacturing a phase delay film according to the present invention may form a pattern differently by setting only the structure of an electrode or a magnet to form an electric field or a magnetic field. There is an advantage that no additional process is required.

Claims

Method for producing a phase retardation film comprising the following steps:

(a) applying a polymerizable liquid crystal composition onto a substrate;

(b) providing an electric field or a magnetic field to the substrate to which the polymerizable liquid crystal composition is applied to form an orientation in the polymerizable liquid crystal composition in a predetermined direction; And

(c) polymerizing the polymerizable liquid crystal composition by providing heat or light to the polymerizable liquid crystal composition having the alignment.
The method of claim 1, wherein the step (b) is performed such that the polymerizable liquid crystal composition is formed so that the orientations in different directions cross each other at regular intervals.
The method of claim 1, wherein the step (b) is characterized in that the polymerizable liquid crystal composition is formed so as to intersect orthogonality perpendicular to each other at regular intervals.
The method of claim 1, wherein the electric field or the magnetic field generating device is located under the substrate.
The method of claim 1, wherein the electric field or the magnetic field generating device is located on the substrate.
The method of claim 1, wherein the electric field or the magnetic field generating device is formed on the substrate itself.
The method of claim 1, wherein the electric field or the magnetic field generating device is formed in a zigzag form.
The method of claim 1, wherein the electric field is 1.5 V / 탆 or more.
The method of claim 1, wherein the electric field is 5.5 V / µm or more.
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.
8. The method of claim 7, wherein the generator of the electric field or the magnetic field is alternately connected.
The method of claim 1, wherein the substrate is selected from the group consisting of polyether sulfone (PES), polyimide (PI), cyclo olefin polymer (COP), polyethylene terephthalate (PET), triacetyl cellulose (TAC), polycarbonate (PC), and glass. Manufacturing method characterized in that it is selected.
The method according to claim 1, wherein the polymerizable liquid crystal composition is a liquid crystal compound having a functional group of an acryl group, a vinyl ether group or an epoxide.
The method according to claim 1, wherein the polymerizable liquid crystal composition coating layer of step (c) delays the phase of λ / 4.
A phase delay film produced by the method according to any one of claims 1 to 15.