KR20170076370A - Polarizing Element - Google Patents

Abstract

A method of manufacturing a polarizing element, and a use of a polarizing element. The exemplary polarizing element can be manufactured simply and continuously in a roll-to-roll process as well as in a thin form. Such a polarizing element can be used, for example, for improving brightness of a display device.

Description

[0002] Polarizing Element [

The present application relates to a polarizing element, a method of manufacturing the polarizing element, and a use of the polarizing element.

As a brightness enhancement system of a display device, for example, a technique of inserting a brightness enhancement film between a light source and a light-source-side absorption type polarizing plate has been used. The brightness enhancement film is generally referred to as a prism sheet, a brightness enhancement film (BEF), or a dual brightness enhancement film (DBEF). As the absorption type polarizing plate, for example, a polymer elongation film on which iodine or a dichroic dye is adsorbed is mainly used. As the brightness enhancement film, for example, DBEF is mainly used.

However, in order to improve the brightness enhancement system, the transmission axes of the absorption type polarizing plate and the brightness enhancement film should be arranged in parallel. Normally, the polymer stretched film is stretched in the coating direction so that the absorption axis is formed in the coating direction, There is a problem that the manufacturing process is troublesome because any one of the polymer stretched film or the DBEF must be cut and lapped again for the above arrangement.

Korean Patent Publication No. 2004-0004138

The present application provides a polarizing element, a method of manufacturing the polarizing element, and uses of the polarizing element.

An exemplary polarizing element may comprise a reflective polarizing layer and an absorptive polarizing layer present on one side of the reflective polarizing layer. The absorption type polarizing layer may include, for example, a polymerizable liquid crystal compound and a dichroic dye. 1 shows an example of an optical element including a reflection type polarizing layer 101 and an absorption type polarizing layer 102 which is present on one side of the reflection type polarizing layer and includes a polymerizable liquid crystal compound and a dichroic dye .

In the present application, the " reflection type polarizing layer " may mean a functional element exhibiting selective transmission and reflection characteristics with respect to incident light. The reflection type polarizing layer may have a function of transmitting light that vibrates in one direction from incident light that vibrates in various directions, and reflects light that vibrates in the other direction, for example. In the present application, the " absorption type polarizing layer " may mean a functional element exhibiting selective transmission and absorption characteristics with respect to incident light. The absorption type polarizing layer may have a function of transmitting light that vibrates in one direction from the incident light that vibrates in various directions, and absorbs light that vibrates in the other direction

The transmission axis of the reflection type polarizing layer may be arranged so as to be parallel to the transmission axis of the absorption type polarizing layer. For example, the absolute value of the angle formed by the transmission axis of the reflection type polarizing layer and the transmission axis of the absorption type polarizing layer may be within the range of 0 to 5 degrees. When the transmission axis of the reflection type polarizing layer and the transmission axis of the absorption type polarizing layer form an angle within the above range, the transmission of polarized light oscillating in the direction parallel to the transmission axis is enhanced and the polarized light is oscillated in the direction perpendicular to the transmission axis A polarizing element having a brightness enhancement function can be realized by reflecting and absorbing polarized light.

As the reflective polarizing layer, a known reflective polarizer known to exhibit selective transmission and reflection characteristics with respect to incident light can be used as described above. For example, a DBEF (Dual Brightness Enhancement Film), a Lyotropic Liquid Crystal (LLC layer), or a wire grid polarizer may be used as a reflective polarizing layer. According to one embodiment of the present application, DBEF can be used as a reflective polarizing layer.

The thickness of the reflective polarizing layer can be suitably selected within a range that does not impair the desired physical properties. For example, when DBEF is used as the reflective polarizing layer, the thickness of the DBEF may be about 10 μm to about 1 mm, but is not limited thereto. When the reflection type polarizing layer has a thickness within the above range, for example, it is possible to appropriately express the selective transmission and reflection characteristics with respect to incident light. According to one embodiment of the present application, a DBEF having a thickness of about 100 μm to 300 μm may be used, but the present invention is not limited thereto.

The absorption type polarizing layer may include a polymerizable liquid crystal compound and a dichroic dye as described above. Such an absorption type polarizing layer is called a so-called guest-host type polarizing element. For example, dichroic dyes are arranged together according to the arrangement of polymerizable liquid crystal compounds to absorb light parallel to the alignment direction of the dyes, Anisotropic light absorption effect can be exhibited.

The "polymerizable liquid crystal compound" in the present application may mean a compound containing a moiety capable of exhibiting liquid crystallinity, such as a mesogen skeleton, and containing at least one polymerizable functional group. The polymerizable liquid crystal compound can be contained in the absorption type polarizing layer, for example, in a polymerized state. In the present application, "the polymerizable liquid crystal compound is contained in a polymerized form" may mean a state in which the liquid crystal compound is polymerized to form a skeleton such as a main chain or side chain of the liquid crystal polymer in the liquid crystal polymer film.

As the polymerizable liquid crystal compound, for example, a compound represented by the following formula (1) can be used.

[Chemical Formula 1]

Wherein A is a single bond, -COO- or -OCO-, and R 1 to R ₁₀ are each independently selected from the group consisting of hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, At least one of R ₁ to R ₁₀ is -OQP or a substituent of the following formula (2), or two adjacent substituents of R ₁ to R ₅ or two adjacent substituents of R ₆ to R ₁₀ are And Q represents an alkylene group or an alkylidene group, and P represents an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, Or a polymerizable functional group such as a methacryloyloxy group:

(2)

Wherein B is a single bond, -COO- or -OCO-, and R ₁₁ to R ₁₅ are each independently selected from the group consisting of hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or -OQP , At least one of R ₁₁ to R ₁₅ is -OQP, or R ₁₁ To R < ₁₅ > are connected to each other to form benzene substituted with -OQP, wherein Q is an alkylene group or an alkylidene group, and P is an alkenyl group, an epoxy group, a cyano group, A methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

The formation of benzene substituted with -OQP in the above two substituents in Formulas 1 and 2 means that two adjacent substituents are connected to each other to form a naphthalene skeleton substituted with -OQP as a whole have.

In the above formula (2), "-" on the left side of B may mean that B is directly connected to benzene of the formula (1).

The term "single bond" in the above formulas (1) and (2) means a case where no separate atom exists in the part represented by A or B. For example, when A is a single bond in formula (I), benzene on both sides of A may be directly connected to form a biphenyl structure.

As the halogen in the above formulas (1) and (2), chlorine, bromine or iodine can be exemplified.

The term alkyl group in the present application includes, unless otherwise specified, a linear or branched alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, Or a cycloalkyl group having 3 to 16 carbon atoms or 4 to 12 carbon atoms. The alkyl group may be optionally substituted with one or more substituents.

The term alkoxy group in the present application may mean an alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms unless otherwise specified. The alkoxy group may be linear, branched or cyclic. In addition, the alkoxy group may be optionally substituted with one or more substituents.

The term alkylene group or alkylidene group in the present application may mean an alkylene group or an alkylidene group having 1 to 12 carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms unless otherwise specified. The alkylene group or alkylidene group may be linear, branched or cyclic. Also, the alkylene group or alkylidene group may be optionally substituted with one or more substituents.

Unless otherwise specified, the alkenyl group in the present application may mean an alkenyl group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms. The alkenyl group may be linear, branched or cyclic. In addition, the alkenyl group may be optionally substituted with one or more substituents.

In the general formulas (1) and (2), P is preferably an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, more preferably an acryloyloxy group or a methacryloyloxy group, And more preferably an acryloyloxy group.

Examples of the substituent which may be substituted in the specific functional group in the present application include alkyl groups, alkoxy groups, alkenyl groups, epoxy groups, oxo groups, oxetanyl groups, thiol groups, cyano groups, carboxyl groups, acryloyl groups, methacryloyl groups, Acryloyloxy group, methacryloyloxy group, aryl group, and the like, but the present invention is not limited thereto.

The polymerizable liquid crystal compound may be contained in the absorption type polarizing layer in a horizontally oriented state, for example. In the present application, "horizontal alignment" means that the optical axis of the absorption type polarizing layer including the polymerized liquid crystal compound is in the range of from about 0 degrees to about 25 degrees, from about 0 degrees to about 15 degrees, from about 0 degrees 10 degrees, about 0 degrees to about 5 degrees, or about 0 degrees.

The absorption type polarizing layer may also comprise a dichroic dye. As used herein, the term " dye " may mean a material capable of intensively absorbing and / or deforming light within a visible light region, for example, at least a part or whole range within a wavelength range of 400 nm to 700 nm, Quot; sex dye " may mean a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region.

Examples of dichroic dyes include those known to be capable of forming so-called guest host type polarizing elements, for example, known dyes known to have properties that can be arranged according to the orientation of the polymerizable liquid crystal compound Can be used. As such dichroic dyes, for example, known dyes such as azo dyes or anthraquinone dyes can be used. Specifically, azo dyes F355 (registered trademark), F357 (registered trademark), or F593 (registered trademark) Nippon Kankoh Shikiso kenkyusho Ltd.), and dyes of a kind known to exhibit the above-mentioned effects, but the present invention is not limited thereto.

The dichroic ratio of the dichroic dye can be suitably selected within a range that does not impair the desired physical properties. The dichroic ratio in the present application may mean a value obtained by dividing the absorption of the polarized light parallel to the long axis direction of the dichroic dye by the absorption of the polarized light parallel to the direction perpendicular to the long axis direction. The dichroic dye may have a dichroic ratio of, for example, 5 or more, 6 or more, or 7 or more. The dichroic dye may be, for example, at least a part of the wavelength within the wavelength range of the visible light region, for example, within the wavelength range of about 380 nm to 700 nm or about 400 nm to 700 nm, Can be satisfied. The upper limit of the dichroic ratio may be, for example, 20 or less, 18 or less, 16 or less, or 14 or less.

The content of the dichroic dye in the absorption type polarizing layer can be appropriately adjusted within a range not to impair the purpose of the present application. As one example, the dichroic dye may be contained in the absorptive polarizing layer at a ratio of about 7 parts by weight, about 6 parts by weight or less, or about 5 parts by weight or less, based on 100 parts by weight of the polymerizable liquid crystal compound. The dichroic dye may be contained in the absorption type polarizing layer at a ratio of about 0.5 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more based on 100 parts by weight of the polymerizable liquid crystal compound. When the content of the dichroic dye is within the above range, the selective absorption characteristics can be suitably exhibited without interfering with the polymerization of the polymerizable liquid crystal compound.

The absorption type polarizing layer may be, for example, a coating layer of a polarizing material including a polymerizable liquid crystal compound and a dichroic dye. Therefore, the polarizing element can be manufactured simply and continuously in a roll-to-roll process, and thinning of the element through structure simplification is possible.

The thickness of the absorption type polarizing layer can be suitably selected in consideration of the intended use of the polarizing element or the like. The absorption type polarizing layer may have a thickness of, for example, from about 0.1 탆 to 1 탆, from about 0.2 탆 to 0.9 탆, from about 0.3 탆 to 0.7 탆, from about 0.4 탆 to 0.6 탆, from about 0.45 탆 to 0.65 탆, Lt; / RTI > In the case of a polymeric stretched film conventionally adsorbed with iodine or a dichroic dye, durability and the like are deteriorated and the film has a composite film structure of not only the stretched film but also a protective film such as TAC, and therefore has a total thickness of 100 μm to 150 μm Lt; RTI ID = 0.0 > and / or < / RTI > On the other hand, the absorption type polarizing layer of the present application can exhibit the same or higher polarizing efficiency even when it is made thinner than when the conventional polarizing film is used.

In one example, the polarizing element may have a PE ratio (Polarizer Effectiveness) of at least about 80%, at least 85%, at least 90%, at least 95%, at least 96%, or at least 97%. The PE ratio may be a value measured according to the polarization efficiency evaluation method described in the concrete contents for carrying out the invention.

The polarizing element of the present application can also exhibit excellent polarization efficiency while minimizing the decrease in transmittance. In one example, the polarizing element may have a single transmittance of about 20% or more, about 25% or more, about 30% or more, or about 35% or more. The above-mentioned simple transmittance may mean the transmittance of incident light that passes through one polarizing element when air is used as a base.

The polarizing element may further include an alignment film, for example, and the alignment film may be formed adjacent to the absorption type polarizing layer, for example. Fig. 2 exemplarily shows a polarizing element including a reflection type polarizing layer 101, an absorption type polarizing layer 102 and an alignment film 201 disposed adjacent to the absorption type polarizing layer.

As the alignment film, any kind can be used as long as it can suitably control the alignment of the polymerizable liquid crystal compound in the adjacent absorption type polarizing layer. For example, the alignment film may be a contact alignment film such as a rubbing alignment film, , For example, an alignment film known to be capable of exhibiting alignment properties by a non-contact method such as irradiation of linearly polarized light or the like can be used. On the other hand, when DBEF is used as the reflective polarizing layer in the present application, since the liquid crystal is oriented by the stretching direction of the DBEF, the DBEF can simultaneously perform the role of the alignment film without an additional alignment film.

When the polarizing element includes an additional alignment film, for example, a photo alignment layer containing a photo-alignment compound may be used as the alignment film. The term photo-aligning compound in the present application may mean a compound that is orientationally ordered through irradiation of light and can orient adjacent liquid crystal compounds in the predetermined direction in the aligned state. The oriented compound may be a monomolecular compound, a monomeric compound, an oligomeric compound or a polymeric compound.

The photo directing compound may be a compound containing a photosensitive moiety. Various photo-orientable compounds which can be used for the alignment of liquid crystal compounds are known. Photo-aligning compounds include, for example, compounds that are aligned by trans-cis photoisomerization; Compounds that are aligned by photo-destruction such as chain scission or photo-oxidation; Compounds that are aligned by photo-crosslinking or photopolymerization such as [2 + 2] cycloaddition, [4 + 4] addition cyclization or photodimerization; A compound aligned by photo-Fries rearrangement or a compound aligned by ring opening / closure reaction can be used. Examples of the compounds that are aligned by trans-cis photoisomerization include azo compounds such as sulfonated diazo dye or azo polymer, stilbenes, etc. Examples of the compound which is aligned by photolysis include cyclobutane-1,2,3,4-tetracarboxylic dianhydride, aromatic polysilane or polyester, polystyrene or polyimide, and the like. The compounds that are aligned by photo-crosslinking or photopolymerization include cinnamate compounds, coumarin compounds, cinnamamide compounds, tetrahydrophthalimide compounds, maleimide compounds, (Hereinafter, referred to as an anthracenyl compound) having a chalconyl residue (hereinafter, referred to as a chalcone compound) or an anthracenyl residue (hereinafter referred to as an anthracenyl compound) as a benzophenone compound or a diphenylacetylene compound or a photo- Examples of the compounds that can be aligned by optical freeze rearrangement include aromatic compounds such as benzoate compounds, benzoamide compounds, and methacrylamidoaryl methacrylate compounds, Examples of the compounds to be aligned by the ring-opening / ring closing reaction include spiropyran compounds and the like A [4 + 2] π electron system ([4 + 2] π electronic system), but may be exemplified by compounds such as sorting by a ring opening / ring-closure reaction of, without being limited thereto.

The photo aligning compound may be a monomolecular compound, a monomeric compound, an oligomeric compound, a polymeric compound, or a blend of the photo-aligning compound and the polymer. The oligomeric or macromolecular compound may have a residue derived from the above-described photo-orienting compound or a photo-sensitive residue described above in the main chain or side chain.

Examples of the polymer having a moiety or photosensitizing moiety derived from the photo-orienting compound or capable of being mixed with the photo-aligning compound include polynorbornene, polyolefin, polyarylate, polyacrylate, poly (meth) (Meth) acrylate, poly (amic acid), polymaleinimide, polyacrylamide, polymethacrylamide, polyvinyl ether, polyvinyl ester, polystyrene, polysiloxane, polyacrylonitrile or polymethacrylonitrile But is not limited thereto.

Examples of the polymer that can be contained in the oriented compound include polynorbornene cinnamate, polynorbornene alkoxy cinnamate, polynorbornene allyloyloxy cinnamate, polynorbornene fluorinated cinnamate, polynorbornene chlorinated cinnamate, or Polynorbornene dicinnamate, and the like, but are not limited thereto.

The present application also relates to a method of manufacturing a polarizing element. The polarizing element manufacturing method may include, for example, coating a polarizing material containing a polymerizable liquid crystal compound and an anisotropic dye on one surface of a reflective polarizing layer, and then polymerizing the polymerizable liquid crystal compound in an oriented state .

The above method may be, for example, a method of manufacturing the above-described polarizing element. Therefore, in the above manufacturing method, the contents of the reflection type polarizing layer, the polymerizable liquid crystal compound and the anisotropic dye can be applied to the polarizing element in the same manner as described above. When the polymerizable liquid crystal compound is polymerized in the aligned state after coating the polarizing material in the above production method, the above-described absorption type polarizing layer may be formed in the item of the polarizing element.

The method of coating the polarizing material on the reflection type polarizing layer is not particularly limited and may be a known method such as roll coating, printing method, inkjet coating, slit nozzle method, bar coating, comma coating, spin coating, By coating through a < RTI ID = 0.0 > coating < / RTI >

The polarizing element can be produced, for example, by coating a polarizing material on the reflective polarizing layer by a simple roll-to-roll process. In the case of the polymeric stretched film on which the dichroic dye or iodine is adsorbed, the stretching in the coating direction proceeds to form the absorption axis in the coating direction, whereas in the reflection type polarizing layer such as DBEF, the reflection axis is formed in the coating width direction In the roll-to-roll process, it is practically impossible to arrange the transmission axes of the polarizing film and the reflective polarizing layer in parallel, and it is troublesome to cut one of the polarizing layers and to laminate them again.

On the other hand, in the present application, since the liquid crystal compound can be oriented by the stretching direction of the reflection type polarizing layer such as DBEF, even in the roll-to-roll process, the transmission axis of the reflection type polarizing layer and the transmission axis of the absorption type polarizing layer are parallel . ≪ / RTI > Alternatively, as will be described later, even when an orientation film is formed to induce the orientation of the intended liquid crystal compound on the reflection type polarizing layer, it is possible to manufacture a polarizing element by a rule-to-roll process.

The polarizing material can be polymerized, for example, in a state in which the polymerizable liquid crystal compound is oriented. The polymerizable liquid crystal compound can be oriented by orienting the reflective polarizing layer such as DBEF in the stretching direction, or by forming an alignment film on the reflective polarizing layer before coating the polarizing substance, without using an alignment film, as described above.

The alignment film can be formed, for example, by forming a layer of an alignment film precursor containing a photo-aligning compound on a reflective polarizing layer and then aligning the photo-aligning compound by irradiation of light. The precursor of the alignment film may contain, for example, an appropriate amount of an initiator in addition to the photo-aligning compound, and may contain other additives such as a surfactant, if necessary.

The precursor layer of the alignment layer can be formed, for example, by coating the precursor with a conventional coating method such as bar coating, comma coating, ink jet coating, or spin coating. Irradiation of light can be performed so that the photo-orientable compound included in the layer of the precursor can be aligned. The alignment of the photo-aligning compound is typically performed using linearly polarized light. The wavelength or intensity of the light to be irradiated may be selected to provide for proper alignment of the photo-orienting compound. Typically, the photo directing compound is aligned by light in the visible or near ultraviolet range, but light in the far ultraviolet or near infrared range may be used if necessary.

The method of polymerizing a polarizing material containing a polymerizable liquid crystal compound is not particularly limited and can be carried out by a known liquid crystal compound polymerization method. For example, the polymerization can be started by adding an appropriate polymerization initiator so as to start the polymerization reaction, and maintaining the proper temperature or by irradiating a suitable active energy ray. When the maintenance at an appropriate temperature and the irradiation of the active energy ray are simultaneously required, the above process can be carried out sequentially or simultaneously. The irradiation of the active energy ray may be performed using, for example, a high-pressure mercury lamp, an electrodeless lamp, or a xenon lamp, and the conditions such as the wavelength, luminous intensity, Can be selected within a range in which the polymerization of the polymerizable liquid crystal compound can be properly carried out.

The present application also relates to the use of polarizing elements. The polarizing element can be used, for example, for improving the brightness of the display device. The display device may include, for example, a light source, and the polarizing element may be disposed so that the reflective polarizing layer is closer to the light exit side of the light source than the absorption polarizing layer. Since the polarizing element exhibits high reflection / absorption for light having a polarization axis in one direction with respect to light incident from the light source and exhibits high transmission for light having a polarization axis perpendicular to the polarization axis in the one direction, The brightness can be improved.

Fig. 3 exemplarily shows the principle of brightness enhancement of the polarizing element. The polarizing element of FIG. 3 has a transmission axis in the y-axis direction, a reflection type polarizing layer 101 having a reflection axis in the x-axis direction and an absorption type polarizing layer 201 having a transmission axis in the y- And the reflection type polarizing layer 101 is disposed adjacent to the light output side of the light source 301. The reflection type polarizing layer 101 is disposed on the light exit side of the light source 301,

The polarized light 1 vibrating in a direction parallel to the transmission axis of the reflective polarizing layer among the light emitted from the light source is reflected by the reflective polarizing layer 101 and the absorption polarizing layer 102 ), And can be discharged to the outside. The polarized light 2 that oscillates in a direction perpendicular to the transmission axis of the reflective polarizing layer out of the light emitted from the light source does not pass through the reflective polarizing layer 101 and is reflected to the light source side. Since the reflected polarized light is sent back to the light source, the polarized light can be reused and the amount of usable light can be increased. Or even if part of the polarized light 3 oscillating in the direction perpendicular to the transmission axis of the reflective polarizing layer passes through the reflective polarizing layer 101, it is absorbed and blocked by the absorptive polarizing layer 102, It does not. Accordingly, the polarizing element exhibits selective transmission and blocking characteristics while increasing the amount of usable light, so that the brightness of the device of the display can be improved.

Specific examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, an inorganic EL display device, a field emission display (FED), a surface field emission display (SPED) A plasma display device, a projection display device (for example, a grating light valve (GLV) display device, a digital micromirror device (Digital Light Processing) device) using an electronic paper (electronic ink or electrophoretic device) And a piezoelectric ceramic display device, but the present invention is not limited thereto. The liquid crystal display device may be, for example, a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct viewing type liquid crystal display device, or a projection type liquid crystal display device. Further, such a display device may be a display device for displaying a two-dimensional image or a stereoscopic display device for displaying a three-dimensional image. The manner of constructing such a display device is not particularly limited, and a conventional method can be applied as long as the polarizing element is used.

The exemplary polarizing element of the present application is not only simple and continuously producible in a roll-to-roll process, but also can be made thin. Such a polarizing element can be used, for example, for improving brightness of a display device.

Figures 1 and 2 illustrate polarizing elements illustratively.
Fig. 3 exemplarily shows the principle of brightness enhancement of the polarizing element.

Hereinafter, the polarizing element will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present application is not limited to the following contents.

Example  One

0.5 g of a dichroic dye (G241, Hayashibara), 10 g of a polymerizable liquid crystal compound (LC242, manufactured by BASF), and 10 g of an initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals Inc.) were placed on a reflective polarizing film (DBEF, ) Was dissolved in toluene solvent (39 g) to prepare a polarizing material having a dry thickness of about 0.5 탆. After orienting the polarizing material in accordance with the drawing direction of the lower DBEF, ultraviolet rays (300 mW / cm ² ) To form an absorption type polarizing layer having a thickness of about 0.5 mu m, thereby producing a polarizing element of Example 1. [

Example  2

Except that a black dye prepared by mixing G207 (Hayashibara Co., Ltd.), G241 (Hayashibara Co., Ltd.) and G472 (Hayashibara Co., Ltd.) as dichroic dyes in a weight ratio of 1: 1: 1 (1.67 g, respectively) The polarizing element was manufactured.

Comparative Example  One

A reflective polarizing film DBEF was prepared in Comparative Example 1.

Test Example  1: Evaluation of polarization efficiency

x 100%로 정의되는 값으로, Tp는 2개의 편광 소자의 투과축을 평행하게 배치한 경우 투과율이고, Tc는 2개의 편광 소자의 투과축을 수직하게 배치한 경우 투과율을 의미한다. 상기 투과율은 V-7100 UV-VIS Spectrophotometer (Jasco 社제)를 이용하여 측정하였다. The polarization efficiency of the polarizing element of Example 1 - 2 and Comparative Example 1 was measured by measuring the PE ratio (Polarizer Effectiveness). The results are shown in Table 1 below. The PE ratio

x 100%, Tp is the transmittance when the transmission axes of two polarizing elements are arranged in parallel, and Tc is the transmittance when the transmission axes of two polarizing elements are arranged vertically. The transmittance was measured using a V-7100 UV-VIS Spectrophotometer (manufactured by Jasco).

As shown in the following Table 1, it can be confirmed that Example 1-2 in which the absorption type polarizing layer was used in combination as compared with Comparative Example 1 using only the reflection type polarizing film was more excellent in polarizing efficiency.

Comparative Example 1 Example 1 Example 2 PE ratio (%) 96.73 99.20 97.11

101: reflection type polarizing layer
102: absorption type polarizing layer
201: alignment film
301: Light source

Claims (16)

A reflective polarizing layer; And an absorption type polarizing layer which is present on one side of the reflection type polarizing layer and comprises a polymerizable liquid crystal compound and a dichroic dye. The polarizing element according to claim 1, wherein the absolute value of the angle formed by the transmission axis of the reflection type polarizing layer and the transmission axis of the absorption type polarizing layer is within the range of 0 to 5 degrees. The polarizing element according to claim 1, wherein the reflective polarizing layer comprises a Dual Brightness Enhancement Film (DBEF), a Lyotropic Liquid Crystal (LLC layer) or a wire grid polarizer. The polarizing element according to claim 1, wherein the polymerizable liquid crystal compound is contained in the absorption type polarizing layer in a horizontally aligned state. The polarizing element according to claim 1, wherein the dichroic dye exhibits a maximum absorbance within a wavelength range of 400 nm to 700 nm. The polarizing element according to claim 1, wherein the dichroic ratio of the dichroic dye is 5 to 20. The polarizing element according to claim 1, wherein the dichroic dye is included in the absorption type polarizing layer at a ratio of 0.5 to 7 parts by weight based on 100 parts by weight of the polymerizable liquid crystal compound. The polarizing element according to claim 1, wherein the absorption type polarizing layer is a coating layer of a polarizing material including a polymerizable liquid crystal compound and a dichroic dye. The polarizing element according to claim 1, wherein the absorption type polarizing layer has a thickness of 0.1 占 퐉 to 1 占 퐉. The polarizing element according to claim 1, further comprising an alignment film disposed adjacent to the absorption type polarizing layer. The polarizing element according to claim 10, wherein the alignment film comprises a photo alignment layer comprising a photo-aligning compound. A polarizing material containing a polymerizable liquid crystal compound and an anisotropic dye is coated on one surface of the reflective polarizing layer, and then the polymerizable liquid crystal compound is polymerized in an aligned state. The method of manufacturing a polarizing element according to claim 12, further comprising forming an alignment film on one surface of the reflective polarizing layer before coating the polarizing material. The method of manufacturing a polarizing element according to claim 12, wherein the polarizing element is manufactured by a roll-to-roll process. A display device comprising the polarizing element of claim 1. The display device according to claim 15, further comprising a light source, wherein the reflective polarizing layer is disposed adjacent to a light exit side of the light source.

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