KR100756067B1 - Polarizing optical body and a method for making thereof - Google Patents

Abstract

The present invention provides a polarizing optical body that polarizes incident light and emits the light in order to reduce light loss due to diffuse reflection, and to provide a light efficiency, high temperature reliability, and easy manufacturing, and a manufacturing method thereof. A polymer network layer comprised of at least a first and a second medium, wherein the first medium is a crosslinkable polymer liquid crystal, the liquid crystal molecules of which are aligned in a first axial direction in a predetermined direction, wherein the second medium is light or heat As curable resin, the polarizing optical body which is a granular or reticulated polymer is provided.

Description

Polarizing optical body and its manufacturing method {POLARIZING OPTICAL BODY AND A METHOD FOR MAKING THEREOF}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a polarizing optical body and a method for manufacturing the same, and more particularly, to a polarizing optical body using a diffusion transmission effect of light and a manufacturing method thereof.

Prior art associated with this application

Korean Patent Registration Publication No. 10-0424519

Patent Registration Publication No. 10-0409062

In already known patent publication No. 10-0424519, a polarizer disposed between a display means and an illumination means for generating an image using polarization is disclosed. The polarizer comprises a first polymeric powder phase dispersed in a second polymeric continuous phase, the refractive index along the first axis between the powdery phase and the continuous phase small enough to transmit light in a first polarization state in the direction of the display means. And a refractive index difference between the dispersion phase and the continuous phase along a second axis perpendicular to the first axis that is large enough to diffusely reflect light of the second polarization state in the direction of the illumination means, wherein the illumination means is provided to the polarizer. Altering the polarization state of a portion of the reflected light thereby redirecting the light in a direction opposite to the polarizer direction.

In addition, in other well-known Patent Publication No. 10-0409062, the content of the Patent No. 10-0424519 is further limited, and includes a light extractor and a light comprising a continuous phase which is a polymer and a dispersed phase disposed in the continuous phase. As a combination of the guides, a combination of refractive index difference between the continuous phase and the dispersed phase is 0.05 or more along the first axis and 0.05 or less along the second axis orthogonal to the first axis.

However, these known patents relate to the structure of a diffusely reflective polarizer and a method of manufacturing the same. Here, "diffuse reflection" means the reflection of a light ray incident outside the range of a cone having a slope of about 16 degrees around the specular angle. In order to increase the reflectance of the diffuse reflection, the known patents are configured such that the difference in refractive index between the continuous phase and the dispersed phase is greater than 0.05 in the first axis direction. Thus, the diffusely reflective polarizer according to the conventional patents disperses and distributes the polymer powder phase inside the polymer continuous phase and extends in the longitudinal direction so that one of the continuous phase and the dispersed phase becomes birefringent.

In addition, the above known patents mainly use diffuse reflection and thus require a separate reflection means. In addition, light diffused and reflected by the diffusely reflective polarizer is scattered or diffused in a large part of the device, and wanders, and is eventually absorbed and extinguished.

Furthermore, according to the above known patents, since the synthetic resin is stretched to have birefringence, its manufacturing process is very difficult. That is, since the dispersed phase is elongated in the stretching direction by the stretching of the material, the scattering distribution of light is concentrated in a specific direction, and even in some directions, there is a disadvantage that the scattering is insufficient and appears dark.

Technical challenge

It is an object of the present invention to provide a polarizing optical body and a method of manufacturing the same, which reduce the light loss due to diffuse reflection, which is a problem of the known art, and which have high light efficiency, high reliability for temperature, and are easy to manufacture.

Technical solution

In order to achieve the above object, according to the present invention, in the polarizing optical body to polarize the incident light, the polarizing optical body comprises a polymer network layer consisting of at least a first and a second medium, the first medium is a crosslinkable polymer liquid crystal Wherein the liquid crystal molecules are aligned in a first axial direction in a predetermined direction, and the second medium is a light or thermosetting resin (hereinafter referred to as a 'curable resin'), which provides a polarizing optical body which is a particulate or reticulated polymer. do. The shape of the particles is spherical or indefinite, and the like is not limited.

The polymer network layer composed of the two media as described above has substantially isotropic to homogeneity in the form and distribution of the mixture. As a result, the scattering distribution of light in the polymer network layer is substantially uniform in all directions, and thus, a phenomenon in which light transmittance decreases in a specific direction and becomes dark can be avoided.

Particularly, the crosslinkable polymer liquid crystal and the curable resin have different refractive indices in a first axis direction that is a predetermined direction on a horizontal plane parallel to the polymer network layer, and a second direction that is perpendicular to the first axis on the horizontal plane. It is substantially the same in the refractive index in the axial direction. As a result, the polarization in the direction parallel to the second axial direction proceeds in the medium without change, and the polarization in the other direction is refracted at the interface between the crosslinkable polymer liquid crystal and the curable resin and the direction of the polarization changes. When this process is repeated, the polarization of the other polarization direction gradually has a polarization direction parallel to the second axis direction.

The present invention minimizes light loss due to reflection by using diffusion transmission as a main mechanism instead of diffusion reflection. Here, "diffuse transmission" means transmission of light that is incident outside the range of a cone having an inclination of about 16 degrees around the permeation angle. Thus, in order to use the diffusion transmission phenomenon as the main mechanism, it is necessary to reduce the amount of reflection of the incident light by controlling the degree of diffusion through the difference in the refractive index of the two media and the optimization of the external shape and the mixing distribution. According to a simulation result by the inventor of the present invention, the difference in refractive index between the two media is about 0.04, the interface between the two media in the thickness direction of the polymer network layer is about 20, and the particle size of the curable resin is 1 When it becomes about micrometer, the diffuse reflectance of the polarizing optical body of this invention becomes less than 20%, and polarization property is acquired by making diffuse transmission into a main mechanism.

On the other hand, the birefringence is not made by the stretching method, but the crosslinkable polymer liquid crystal is aligned in a certain direction through the alignment means, and the crosslinking reaction is generated by light or heat to fix the alignment direction, thereby forming the overall birefringence. Easy to manufacture Examples of the alignment means include an alignment film, an electric field, a magnetic field, and an oriented polymer fiber mesh.

According to another embodiment of the present invention, a protective layer that protects the polymer network layer from mechanical impact or abrasion may be further included outside the polymer network layer.

The present invention has the advantage of overcoming the problems of light loss and manufacturing difficulties with known techniques.

Brief description of the drawings

100: polarizing optics

10: crosslinkable polymer liquid crystal

20: curable resin

30: polymer network layer

40: protective layer

200: polarized optical body

210: crosslinkable polymer liquid crystal layer

220: curable resin

230: polymer network layer

240: protective layer

Best Mode for Carrying Out the Invention

Hereinafter, a polarizing optical body according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view conceptually showing the structure of a polarizing optical body 100 according to a first embodiment of the present invention. Referring to FIG. 1, the polarizing optical body 100 of the present invention includes at least a crosslinkable polymer liquid crystal 10 and a polymer network layer 30 made of a curable resin 20 that is separately mixed with the polymer liquid crystal. According to this embodiment, the polymer network layer 30 is heat or light in a state in which the curable resin 20 and the crosslinkable polymer liquid crystal 10 represented by epoxy resin are dissolved and mixed in a common solvent such as xylene, for example. It is preferable that the hardening reaction occurs by forming. Since the purpose of using a common solvent, such as xylene, is to lower the viscosity of the mixed resin 20 and the liquid crystal 10 to be evenly mixed, it should be noted that this process may be omitted depending on the embodiment.

When the curable resin 20 and the crosslinkable polymer liquid crystal 10 are mixed at a mass ratio of about 7: 3 and cause a curing reaction by light or heat, as shown in FIG. 1, the liquid crystal 10 has a particle shape (drop). It hardens together, and the hardened resin 20 surrounds the periphery of the liquid crystal particle 10.

It is preferable that the said crosslinkable polymeric liquid crystal 10 raise | generates a crosslinking reaction by light or heat. In addition, the size of the particles of the molded crosslinkable polymer liquid crystal 10 is preferably about 2 to 100um in diameter.

The crosslinkable polymer liquid crystal 10 and the curable resin 20 differ in their refractive indices so as to substantially affect the polarization direction of light in a predetermined first axial direction on a horizontal plane parallel to the surface of the polymer network layer 30. It is preferable to have a refractive index that does not differ in the second axis direction perpendicular to the first axis direction on the horizontal plane so as not to substantially affect the polarization direction of light.

Specifically, according to the present embodiment, the curable resin 20 is cured in a state where the curable resin 20 and the crosslinkable polymer liquid crystal 10 are mixed, and then the crosslinking is performed using an alignment means such as an electric field or a magnetic field. After aligning the polymeric liquid crystal 10 in a predetermined direction, the aligned liquid crystal 10 is hardened by, for example, irradiation with ultraviolet rays. The alignment direction of the crosslinkable polymer liquid crystal 10 is such that the minor axis direction of the liquid crystal molecules is parallel to the second axis direction, and the major axis direction thereof is parallel to the first axis direction.

By doing so, there is almost no difference in refractive index between the liquid crystal 10 and the curable resin 20 in the short axis direction (ie, the second axis direction) of the liquid crystal molecules, and the polarization of light in the long axis direction (ie, the first axis direction) of the liquid crystal molecules. The difference in refractive index can be generated to affect the direction. Therefore, the polarization in the second axial direction proceeds without a substantial change in the polarization direction, and the polarization in the direction different from the second axial direction is refracted at the interface between the liquid crystal 10 and the curable resin 20, Change occurs. As this process is repeated, the light passing through the polarizing optical body of the present invention has polarized light in a direction substantially parallel to the second axis direction.

Here, when the curable resin 20 is cured using light, it should be noted that light must be used at different wavelengths so that the liquid crystal 10 is not cured together.

The polymer network layer 30 preferably has homogeneity or isotropy as a whole in its form and distribution of the two media. To this end, the curable resin 20 and the crosslinkable polymer liquid crystal 10 are sufficiently mixed and homogeneously mixed, and the cured resin 20 and the crosslinked polymer liquid crystal 10 should be mixed so as not to apply stress or tensile force in a specific direction after the polymer network layer 30 is formed. Therefore, when manufacturing the polarizing optical body 100 of the present invention in the form of a film, the moving speed or the winding speed of the film should be kept uniform. In addition, in the alignment of the crosslinkable polymer liquid crystal 10, it is preferable to align by an electric field, a magnetic field, or the like so that a tensile force or the like in a specific direction is not applied. In addition, the polymer network layer 30 is preferably birefringent or less than 0.01.

Furthermore, it is preferable that a protective layer 40 is additionally included outside the polymer network layer 30 to protect it from mechanical impact or abrasion.

Next, according to another embodiment of the present invention, the mixing ratio of the curable resin and the crosslinkable polymer liquid crystal may be mixed so as to be about 3: 7. When the curing reaction occurs in this state, the liquid crystal forms particles (drops). The curable resin is cured into a net shape between the liquid crystal layers. Other details are the same as the above-described embodiment, so detailed description thereof will be omitted.

Next, according to another embodiment of the present invention, as shown in Figure 2, the polarizing optical body 200 of the present invention, the cross-linkable polymer liquid crystal layer 210 and the optical refraction mixed and distributed in the polymer liquid crystal layer 210 Polymer network layer 230 consisting of particles 220. The photorefractive particles 220 may be selected from polymer particles such as polyethylene particles, polyurethane particles, or inorganic particles such as silica particles.

According to the present embodiment, the photorefractive particles 220 are mixed while the crosslinkable polymer liquid crystal 210 is dissolved in a solvent such as chloroform. The photorefractive particles 220 may have a spherical shape, a rod shape, a plate shape, or the like, but these particles 220 should be formed to be substantially isotropic to homogeneous by being uniformly distributed throughout the crosslinkable polymer liquid crystal layer 210. By doing so, the scattering distribution of light in the polarizing optical body 200 may be uniform in all directions, thereby preventing the phenomenon of appearing dark in a specific direction.

Specifically, the photorefractive particles 220 are mixed with the crosslinkable polymer liquid crystal solution, and the mixture is agitated sufficiently to be mixed evenly, so that a stress or a tensile force in a specific direction is not applied. In the state where the photorefractive particles 220 are mixed with the crosslinkable polymer liquid crystal layer 210, the photorefractive particles 220 are coated on a substrate such as a transparent film, and the solvent is volatilized. Subsequently, the liquid crystal molecules are aligned by applying an electric field or a magnetic field, and the aligned liquid crystal layer 210 is irradiated with ultraviolet rays to cure the liquid crystal layer 210. The alignment direction of the liquid crystal molecules is the same as described above with reference to FIG. 1.

By doing so, there is no substantial difference in the refractive index between the liquid crystal layer 210 and the photorefractive particles 220 in the minor axis direction (ie, the second axis direction) of the liquid crystal molecules, and in the long axis direction (ie, the first axis direction) of the liquid crystal molecules. It is possible to generate a difference in the refractive index to affect the polarization direction of the light.

According to the polarizing optical body 200 according to the present invention, since the diffusion transmission amount is larger than the diffusion reflection amount of the light passing therethrough, the light transmission due to reflection can be minimized to improve the light transmittance. In order to maintain the diffuse reflection amount below 20%, the difference in refractive index between the crosslinkable polymer liquid crystal layer 210 and the photorefractive particles 220 is about 0.04, and the size of the photorefractive particles 220 is about 1 μm in diameter.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

According to the present invention, by using diffusion transmission as a main mechanism instead of diffuse reflection with high light loss, the light transmission efficiency is increased and scattering distribution is almost symmetrical to prevent dark phenomenon in a specific direction and to facilitate manufacturing of a polarizing optical body. Can provide.

Claims (22)

In the polarizing optical body which polarizes the incident light and exits, A polymeric network layer consisting of at least a first and a second medium, The first medium is a crosslinkable polymer liquid crystal, the liquid crystal molecules are aligned in a first axial direction of a predetermined direction, The second medium is a light or heat curable resin, the polarizing optical body is a particulate or reticulated polymer. The method of claim 1, The crosslinkable polymer liquid crystal and curable resin, The refractive indices are different from each other in the first axial direction in a predetermined direction on a horizontal plane parallel to the polymer network layer, And a polarization optical body substantially equal in refractive index in a second axis direction which is a direction perpendicular to the first axis on the horizontal plane. The method of claim 2, The crosslinkable polymer liquid crystal, The polarization optical body of which the axial direction of this liquid crystal molecule becomes parallel to the said 2nd axial direction, and the long-axis direction is aligned parallel to the said 1st axial direction. The method of claim 1, The difference in refractive index of the first and second media is substantially 0.04, Substantially 20 interfaces between the two media in the thickness direction of the polymer network layer, The polarizing optics whose particle size of the said curable resin is substantially 1 micrometer. The method of claim 1, And a protective layer that protects the polymer network layer from mechanical impact or wear on the outside of the polymer network layer. In the manufacturing method of the polarizing optical body which polarizes incident light and it exits, Evenly mixing the light or thermosetting resin with the crosslinkable polymer liquid crystal; Forming a polymer network layer comprising the curable resin and the crosslinkable polymer liquid crystal by causing a curing reaction by heat or light; Aligning the crosslinkable polymer liquid crystal molecules in a predetermined direction by using an alignment means that does not apply stress or tensile force in a specific direction; And Fixing the aligned crosslinkable polymer liquid crystal. The method of claim 6, The mixing step, And the curable resin and the crosslinkable polymer liquid crystal are mixed at a ratio of about 7: 3. The method of claim 6, The crosslinkable polymer liquid crystal produces a crosslinking reaction by light or heat. The method of claim 6, The particle size of the molded crosslinkable polymer liquid crystal has a diameter of about 2 to 100um of the method of manufacturing a polarizing optical body. The method of claim 6, The crosslinkable polymer liquid crystal and curable resin, The refractive indices are different from each other in the first axial direction in a predetermined direction on a horizontal plane parallel to the polymer network layer, And a method of manufacturing a polarizing optical body substantially equal in refractive index in a second axis direction which is a direction perpendicular to the first axis on the horizontal plane. The method of claim 10, The crosslinkable polymer liquid crystal has a short axis direction of liquid crystal molecules parallel to the second axis direction, and a long axis direction thereof is aligned parallel to the first axis direction. The method of claim 6, The said crosslinkable polymeric liquid crystal is a manufacturing method of the polarizing optical body aligned using an electric field or a magnetic field as an orientation means. The method of claim 6, The mixing step, And the curable resin and the crosslinkable polymer liquid crystal are mixed in a ratio of about 3: 7. In the polarizing optical body which polarizes the incident light and exits, A polymeric network layer consisting of at least a first and a second medium, The first medium is a crosslinkable polymer liquid crystal layer, the liquid crystal molecules are aligned in a first axial direction of a predetermined direction, The second medium is a polarizing optical body is a photorefractive particles that are mixed in the polymer liquid crystal layer to refracted incident light. The method of claim 14, The photorefractive particles, A polarizing optical body selected from the group consisting of polymer particles comprising polyethylene particles and polyurethane particles, and inorganic particles comprising silica particles. The method of claim 14, The crosslinkable polymer liquid crystal layer and the photorefractive particles, The refractive indices are different from each other in the first axial direction in a predetermined direction on a horizontal plane parallel to the polymer network layer, And a polarization optical body substantially equal in refractive index in a second axis direction which is a direction perpendicular to the first axis on the horizontal plane. The method of claim 16, The crosslinkable polymer liquid crystal layer, The polarization optical body of which the axial direction of this liquid crystal molecule becomes parallel to the said 2nd axial direction, and the long-axis direction is aligned parallel to the said 1st axial direction. The method of claim 14, The difference in refractive index of the first and second media is substantially 0.04, A polarizing optical body having a size of the photorefractive particles substantially 1㎛. The method of claim 14, And a protective layer that protects the polymer network layer from mechanical impact or wear on the outside of the polymer network layer. In the manufacturing method of the polarizing optical body which polarizes incident light and it exits, Mixing the photorefractive particles evenly in a state where the crosslinkable polymer liquid crystal is in a liquid phase; Coating the photorefractive particles with the crosslinkable polymer liquid crystal layer, and coating the substrate and evaporating a solvent to form a polymer network layer including the crosslinkable polymer liquid crystal layer and photorefractive particles; Aligning the crosslinkable polymer liquid crystal molecules in a predetermined direction by using an alignment means that does not apply stress or tensile force in a specific direction; And Fixing the aligned crosslinkable polymer liquid crystal. The method of claim 20, The crosslinkable polymer liquid crystal layer and the photorefractive particles, The refractive indices are different from each other in the first axial direction in a predetermined direction on a horizontal plane parallel to the polymer network layer, And a method of manufacturing a polarizing optical body substantially equal in refractive index in a second axis direction which is a direction perpendicular to the first axis on the horizontal plane. The method of claim 20, The said crosslinkable polymer liquid crystal layer has a short axis direction of liquid crystal molecules parallel to the second axis direction, and the long axis direction thereof is aligned in parallel with the first axis direction.

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