KR20050004455A - A method of fabricating retardation film using of ion beam - Google Patents

Abstract

PURPOSE: A method for manufacturing a phase difference film using an ion beam alignment is provided to uniformly align the light axes of liquid crystals with respect to a substrate by irradiating an ion beam at the reactive liquid crystals reacting on light. CONSTITUTION: A light alignment layer is printed on a base film, and then, is hardened. The light alignment layer is aligned by irradiating an ion beam at the light alignment layer. A liquid crystal layer is coated on the aligned light alignment layer. The alignment state of the liquid crystal layer is fixed by irradiating unpolarized UV(UltraViolet) light at the coated liquid crystal layer and polymerizing liquid crystals of the liquid crystal layer. The alignment directions of the liquid crystals are decided by irradiating the ion beam in different directions.

Description

A manufacturing method of retardation film using ion beam orientation {A METHOD OF FABRICATING RETARDATION FILM USING OF ION BEAM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a retardation film using ion beam alignment. In particular, a method for manufacturing a retardation film using ion beam alignment capable of uniformly aligning an optical axis of a liquid crystal with respect to a substrate by irradiating an ion beam to a reactive liquid crystal reacting with light. It is about.

In general, liquid crystals have anisotropy in their molecules, and the anisotropy of liquid crystal cells or films composed of the molecules is changed by the distribution of liquid crystal molecules and the degree of tilt angle with respect to the substrate.

In addition, such characteristics become an important factor in changing the polarization of light depending on the viewing angle of the cell or film made of liquid crystal. Due to the inherent characteristics of the liquid crystal, a change in luminance and contrast ratio has been caused by the viewing angles of the upper, lower, left, and right sides of the liquid crystal display, which has been the biggest disadvantage of the liquid crystal display.

In order to compensate for this drawback, a method of attaching a compensation film to compensate for anisotropic distribution according to a viewing angle of a liquid crystal cell has been devised.

This compensation film has an anisotropy distribution as opposed to that of a liquid crystal cell, and is manufactured to eliminate the retardation difference of light depending on the viewing angle when combined with the cell.

In general, a compensation film causes a change in phase difference with respect to transmitted light by a polymer film, and the film is stretched in a predetermined direction to have birefringence by inducing anisotropy of molecules.

In more detail, when an external magnetic field is applied to a Twistic Nematic (TN) liquid crystal display in a normally black mode, liquid crystal molecules arrange in response to an electric field. Light transmission occurs based on the equation.

I = Io sin ² [θ (1 + u ² ) 1/2] u = πR / θλ, R = Δn

Here, I is intensity of transmitted light, Io is intensity of incident light, Δn is birefringence, d is liquid crystal cell thickness, λ is wavelength of transmitted light, θ is twist angle of twisted nematic liquid crystal, and R is phase difference.

As shown in the above equation, the phase difference is a value that is closely related to the viewing angle. Therefore, in order to improve the viewing angle, compensation of the phase difference is desirable.

Therefore, a uniaxial refractive index anisotropic body and a biaxial refractive index anisotropic body are used for the compensation film provided between the liquid crystal substrate and the polarizing plate for retardation compensation.

1A to 1C are diagrams illustrating refractive index anisotropic ellipsoids of a retardation compensation film. As shown here, uniaxiality and biaxiality are determined depending on whether nx and ny are the same when the refractive indices in the x, y, and z directions of the Cartesian coordinate system are nx, ny, and nz, respectively.

That is, as shown in FIG. 1A, when the refractive indexes of the two directions are the same and the magnitude thereof is different from the other direction, it is referred to as uniaxiality. As shown in FIGS. 1B and 1C, when the three directions have refractive indices of different sizes, it is referred to as biaxiality.

In general, a phase difference compensation film using a uniaxial refractive anisotropic body used is arranged such that the major axis of the ellipsoid is parallel or perpendicular to the surface of the film.

On the other hand, the conventional method of manufacturing a retardation compensation film according to the method of stretching the polymer film in one axis or two axes by using the optical axis of the retardation film to have an arbitrary angle with respect to the film traveling direction can obtain a desired birefringence have.

2 is a view schematically showing a method of manufacturing a phase difference compensation film using a stretching method according to the related art. As shown here, this is a method of changing the direction of the optical axis of the retardation film by changing the stretching ratio of the left and right film.

The retardation films made at this time are specially designed retardation films because the optical axis of the retardation film must be at an arbitrary angle with the optical axis of the polarizing plate in order to be used for optical compensation, as in the LCD. Must be cut

In this method, the method of adjusting the draw ratio is mechanical, and it is not easy to adjust the angle as much as desired, and it is disadvantageous for process efficiency and foreign material management because it must be rolled one by one without bonding to the polarizer. There is this.

3 is a view schematically showing the structure of a general optical film. As shown therein, an adhesive and protective film layer is formed on the polarizing plate, and a retardation film is formed on the adhesive and protective layer. In addition, the adhesion, the protective layer, and the retardation film is sequentially formed on the retardation film again to configure the structure of the optical film in multiple layers.

Therefore, the optical film produced by the stretching method, when the force is not evenly applied to the entire film, there is a problem that the unevenness caused by the local retardation difference occurs, it is not easy to change the orientation axis.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a phase difference film using an ion beam alignment capable of irradiating an ion beam to a reactive liquid crystal reacting with light to orient the optical axis of the liquid crystal with respect to a substrate.

1A to 1C illustrate refractive index anisotropic ellipsoids of a retardation compensation film.

Figure 2 is a view schematically showing a method of manufacturing a phase difference compensation film using a stretching method according to the prior art.

3 is a view schematically showing a structure of a general optical film.

Figures 4a to 4d is a view showing a procedure of a first embodiment of a method for producing a retardation film using the ion beam orientation according to the present invention.

FIG. 5 shows a second embodiment showing a liquid crystal λ / 4 retardation film whose optical axis is 0 ° with the film advancing direction; FIG.

FIG. 6 shows a third embodiment showing a liquid crystal [lambda] / 4 retardation film whose optical axis has an arbitrary angle with the film advancing direction; FIG.

7A to 7C show a fourth embodiment showing a patterned liquid crystal λ / 4 phase difference film whose optical axis is at an angle with the film traveling direction.

In order to achieve the above object, a method of manufacturing a phase difference film using an ion beam orientation according to the present invention,

Printing a photo-alignment film on the base film and then curing the optical alignment film;

Irradiating an ion beam on the photoalignment layer to align the photoalignment layer;

Coating a liquid crystal on the alignment-treated photo alignment layer;

The coated liquid crystal is characterized in that it comprises the step of irradiating unpolarized ultraviolet light to cause polymerization to fix the alignment state of the liquid crystal.

Here, in particular, in the step of aligning the photoalignment layer by irradiating an ion beam on the photoalignment layer, the orientation of the liquid crystal material is determined by irradiating different directions of the ion beam on a mask in which a pattern is formed on the photo alignment layer. Has its features.

In particular, the characteristic is that the orientation angle is determined according to the irradiation angle of the ion beam irradiated on the optical alignment layer and the type of the alignment layer.

Here, in particular, the base film on which the photo-alignment film is printed is characterized in that polyester, polycarbonate (PC), triacetate cellulose (TAC), polyvinyl alcohol (PVA), and polyimide (PI) are used.

Here, in particular, the printed alignment layer is characterized in that it is formed of an inorganic material or an organic material.

Here, in particular, the liquid crystal material coated on the alignment layer is characterized in that it is a curable liquid crystal material including a curing reactor as a uniaxial or biaxial material.

Here, in particular, the liquid crystal of the liquid crystal material is characterized in that it is a nematic liquid crystal.

According to the present invention, it is possible to cure the alignment of the coated liquid crystal material in a predetermined direction without performing the rubbing process of the alignment film.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4A to 4D are diagrams illustrating a procedure of a first embodiment of a method of manufacturing a retardation film using ion beam orientation according to the present invention.

As shown in FIG. 4A, first, an organic polymer material called an optical alignment film is coated on a substrate or a base film in order to align liquid crystal molecules in a specific direction, and then, after blowing and aligning the solvent at a temperature of about 60 to 80 ° C., 80 It hardens at the temperature of about 200 degreeC.

The base film may be an optically transparent plastic film such as polyester can be used and maintain the flatness, polycarbonate (PC), triacetate cellulose (TAC), polyvinyl alcohol (PVA), polyimide (PI), etc. Can be.

As a material for forming the optical alignment layer, a polyimide-based organic material is used.

Subsequently, as shown in FIG. 4B, an ion beam is irradiated onto the photoalignment layer to align the photoalignment layer. In particular, the optical axis of the retardation film manufactured by arbitrarily adjusting the orientation direction of the photo-alignment film is made to have an arbitrary angle with respect to the advancing direction of a film.

In more detail, the ion beam source generates ions and generates an ion beam, which ionizes the injected gas by the voltage difference between the cathode and the anode to generate a plasma containing electrons and ions, and in the generated plasma The extraction electrode passes through the passage of the ion beam drawing medium and is drawn out into the ion beam.

The ion beam extracted from the discharged plasma is accelerated by the action of an electric field applied to the ion beam acceleration medium and irradiated at a predetermined angle on the substrate.

Here, the substrate is inclined at a predetermined angle with respect to the ion beam to be irradiated, thereby forming a desired alignment pattern on the alignment layer applied on the substrate by using the ion beam, and the initial arrangement state of the liquid crystal molecules, that is, free It can form a tilt.

At this time, an alignment film of an organic material such as polyimide is coated on the substrate, and the organic material used as the alignment film such as the polyimide is divided into a main chain and a side chain as a chemical structure.

The main chain serves to align the liquid crystal molecules in one direction, and the side chain serves to form a pretilt angle.

In particular, the side chain reacts upon irradiation with the ion beam so that a predetermined portion is broken so that the liquid crystal molecules are oriented with orientation upon orientation.

As such, the ion beam generated from the ion beam source is drawn in the normal direction of the ion beam source and is pretilt angle of the liquid crystal molecules by the irradiation angle (θ 2) to the alignment layer on the substrate inclined at a predetermined angle (θ₁). (pretilt angle) is determined.

In this case, the irradiation angle θ₂ refers to an angle formed between the irradiation direction of the ion beam and the normal direction of the substrate. When the irradiation angle of the ion beam is between 40 and 60 degrees, it has a maximum pretilt angle and has a pretilt angle of 5 degrees or less with respect to the front and rear irradiation angles.

Therefore, in order to obtain a desired pretilt angle uniformly, an ion beam having an appropriate irradiation angle on the entire surface of the alignment film on the substrate should be irradiated with the same energy.

Subsequently, as shown in FIG. 4C, the liquid crystal is coated on the alignment-treated photo alignment layer.

More specifically, 5w% of a curable nematic liquid crystal material and a photoinitiator are dissolved in 3-pentanone to prepare a solution having a concentration of about 15 to 30 wt%, and a thin film on a polyester film coated with a photoalignment film by a roll coating method. After coating and passing through the dryer, the solvent is dried and removed to align the liquid crystal molecules in the direction of the photoalignment film.

At this time, the coating speed of the nematic liquid crystal was 7m / min and the drying conditions are 80 ℃.

Finally, as shown in FIG. 4D, the liquid crystal coated on the photoalignment film is polymerized through irradiation of unpolarized ultraviolet light to fix the alignment state of the liquid crystal. The unpolarized ultraviolet light is irradiated with a 300 W lamp having a central wavelength of 360 nm.

In the liquid crystal film prepared as described above, since the directions of the nematic liquid crystal molecules are all arranged in the same direction as the alignment direction of the photoalignment film, the refractive index distribution of the film is the same as the refractive index distribution of the liquid crystal molecules.

Since the birefringence of the used nematic liquid crystal is Δn = 0.133, the birefringence of the produced film is also measured at Δn = 0.133 which is almost the same as that of the liquid crystal molecules.

The retardation value of the liquid crystal film varies according to the coating thickness, and when the thickness is coated with 0.8 to 1.5 μm, a λ / 4 retardation film acting in the visible light region is produced.

The retardation of the retardation film by adjusting the coating thickness of the nematic liquid crystal has a range between 50 and 400 nm, in detail, 100 to 200 nm.

And the retardation film of the desired size can be manufactured by making a film with various thickness.

FIG. 5 is a view showing a second embodiment showing a liquid crystal λ / 4 retardation film having an optical axis of 0 ° and a film traveling direction, and a detailed description thereof will be omitted with reference to the first embodiment.

As shown in FIG. 5, the horizontal photoalignment material is dissolved in MEK to form a photoalignment film having a solution of 2 wt% concentration, coated on a non-treated polyester film by a roll coating method, and the solvent is dried, and then irradiated with an ion beam. The optical alignment film makes the horizontal alignment.

At this time, the ion beam irradiation apparatus is arranged such that the direction of the ion beam is the same as the traveling direction of the polyester film.

Then, a solution having a concentration of 25wt% was prepared by dissolving 5 wt% of the curable nematic liquid crystal material and photoinitiator in 3-pentanone on the oriented polyester film, and coating the photoalignment film by a roll coating method. The thin film is coated thereon and passed through a dryer to dry and remove the solvent to align the liquid crystal molecules in the direction of the photoalignment film.

At this time, the coating speed of the nematic liquid crystal was 7m / min and the drying conditions are 80 ℃.

In the liquid crystal lambda / 4 phase difference film produced by the method described above, the direction of the liquid crystal molecules are arranged in the same direction as the traveling direction of the polyester film so that the optical axis of the film is the same as the traveling direction of the film.

The prepared film had a thickness of about 1 μm and a refractive index of NX = 1.665 and NY = NZ = 1.535 when measured at a wavelength of 632.8 nm.

FIG. 6 is a view showing a third embodiment showing a liquid crystal λ / 4 retardation film having an optical axis having an arbitrary angle with a film traveling direction, and a detailed description thereof will be omitted with reference to the first embodiment.

As shown in FIG. 6, the horizontal photo-alignment material is dissolved in MEK to form a photo-alignment film which is a solution of 2wt% concentration, coated on the untreated polyester film by a roll coating method, and the solvent is dried and irradiated with an ion beam. The photo-alignment film has a horizontal alignment.

In this case, the ion beam irradiation apparatus is arranged so that the ion beam irradiation device is at an angle of 45 ° to the traveling direction of the polyester film.

5 wt% of a curable nematic liquid crystal material and a photoinitiator were dissolved in 3-pentanone to prepare a solution having a concentration of 25 wt%. The solvent is dried and removed to align the liquid crystal molecules in the direction of the photo-alignment film, and then polymerized through irradiation of unpolarized ultraviolet light to fix the alignment state of the liquid crystal, thereby producing a film.

At this time, the coating speed of the nematic liquid crystal was 7m / min, the drying condition was 80 ℃, irradiation of non-polarized ultraviolet light uses a 300 W Lamp with a central wavelength of 360nm.

In the liquid crystal lambda / 4 phase difference film prepared by the method described above, the direction of the liquid crystal molecules are arranged at a 45 degree angle with the traveling direction of the polyester film so that the optical axis of the film forms a 45 degree angle with the traveling direction of the film.

The thickness of the produced film was about 1 μm, and the refractive index was NX = 1.665 and NY = 1.NZ = 1.535 when measured at a wavelength of 632.8 nm.

7A to 7C are diagrams illustrating a fourth embodiment showing a patterned liquid crystal λ / 4 phase difference film in which an optical axis forms an angle with a film advancing direction, wherein a detailed description thereof will be described with reference to the first embodiment. It will be omitted.

First, as shown in FIG. 7A, the horizontal photoalignment material is dissolved in MEK to form a photoalignment film, which is a solution of 2wt% concentration, coated on the untreated polyester film by a roll coating method, and the solvent is dried, and then irradiated with an ion beam. This makes the photo-alignment film horizontally oriented.

In more detail, in order to form a retardation film having different liquid crystal alignment directions divided into two regions, the alignment direction is determined by irradiating an ion beam such that the polyester film is in a traveling direction and θ ° angle only in one region. Silver mask is used to prevent the ion beam from being irradiated.

Subsequently, as shown in FIG. 7B, the alignment direction is differently determined by irradiating an ion beam at an angle θ ± α ° to form an orientation direction of another region differently after aligning the region at an θ ° angle. . In this case, the ion beam may not be irradiated to the region where the orientation is determined at the θ ° angle by using a mask.

Then, 5 wt% of the curable nematic liquid crystal material and the photoinitiator were dissolved in 3-pentanone on the resultant having the orientation direction determined as described above, to prepare a solution having a concentration of 25 wt%, and a photo-alignment film was coated by a roll coating method A thin film is coated on the film, passed through a drier, and the solvent is dried and removed to align the liquid crystal molecules in the direction of the photoalignment film, and then polymerized through irradiation of unpolarized ultraviolet light to fix the alignment state of the liquid crystal to prepare a film.

At this time, the coating speed of the nematic liquid crystal was 7m / min, the drying condition was 80 ℃, irradiated non-polarized ultraviolet light using a 300 W Lamp with a central wavelength of 360nm.

As shown in FIG. 7C, the liquid crystal λ / 4 retardation film manufactured by the above-described method is arranged such that the direction of the liquid crystal molecules is arranged at a 45 ° angle with the traveling direction of the polyester film so that the optical axis of the film is 45 ° with the traveling direction of the film. Make an angle.

In addition, the thickness of the prepared film is about 1㎛, the refractive index is NX = 1.665, NY = NZ = 1.535 when measured at a wavelength of 632.8 nm.

Therefore, the retardation compensation film using the ion beam alignment according to the above method can easily determine the liquid crystal alignment direction.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, in the method of manufacturing the retardation film using the ion beam alignment according to the present invention, the optical axis of the liquid crystal may be constantly aligned with respect to the substrate by irradiating the ion beam to the reactive liquid crystal reacting with light.

Claims (7)

Printing a photo-alignment film on the base film and then curing the optical alignment film; Irradiating an ion beam on the photoalignment layer to align the photoalignment layer; Coating a liquid crystal on the alignment-treated photo alignment layer; And irradiating non-polarized ultraviolet light to the coated liquid crystal to cause polymerization to fix the alignment state of the liquid crystal. 2. The method of claim 1, In the step of aligning the photoalignment layer by irradiating an ion beam on the photoalignment layer, the orientation direction of the liquid crystal material is determined by irradiating differently the direction of the ion beam on a mask in which a pattern is formed on the photo alignment layer. The manufacturing method of retardation film using ion beam orientation. The method of claim 1, The orientation angle is determined according to the irradiation angle of the ion beam irradiated on the photo-alignment film and the type of the alignment film. The method of claim 1, The base film on which the photo-alignment film is printed is phase difference using ion beam orientation, characterized in that polyester, polycarbonate (PC), triacetate cellulose (TAC), polyvinyl alcohol (PVA), polyimide (PI) is used. Method for producing a film. The method of claim 1, The method of manufacturing a retardation film using ion beam alignment, characterized in that the printed alignment film is formed of an inorganic material or an organic material. The method of claim 1, The liquid crystal material coated on the alignment layer is a uniaxial or biaxial material, the method of manufacturing a retardation film using ion beam orientation, characterized in that the curable liquid crystal material including a curing reactor. The method of claim 1, The liquid crystal of the liquid crystal material is a nematic liquid crystal, characterized in that the manufacturing method of the retardation film using the ion beam orientation.