KR102116368B1 - Polarizing plate and display device comprising the same - Google Patents

Abstract

The present invention relates to a polarizing plate and an image display device including the same.
The polarizing plate according to the present invention includes a polarizer for polarizing light; And a retardation film for retarding the phase of the light, wherein orthogonal color values are -5 to -2, and absorbance at a wavelength of 700 nm is 1.5 or more.

Description

Polarizing plate and image display device including same {Polarizing plate and display device comprising the same}

The present invention relates to a polarizing plate and an image display device including the same, and more specifically, a polarizing plate having a low reflectance in the oblique direction as well as in the front direction of the screen and an image display device comprising the same. It is about.

The polarizing plate includes a polarizer (also referred to as a polarizing film). In general, on one side of the polarizer, a polarizer protective film to protect the polarizer, an adhesive layer to be bonded to the liquid crystal cell, and a peeling film to protect the adhesive layer, etc. Laminated, a polarizer protective film and a surface protective film for protecting the polarizer are laminated on the other side of the polarizer.

The polarizing plate has a great influence on the image quality of the image display device, which may distort or degrade color in particular in an oblique direction.

To overcome this, Korean Patent Publication No. 2013-0066305 discloses a technique to improve the side viewing angle by introducing a positive C plate, and Korean Patent Publication No. 2013-0070559 discloses reverse wavelength dispersion and positive A technique for improving the viewing angle by introducing a C plate is disclosed.

However, the above-mentioned prior arts have improved the front and rear reflection colors, but still have insufficient problems in providing a neutral color.

Republic of Korea Patent Publication No. 2013-0066305 Republic of Korea Patent Publication No. 2013-0070559

The present invention is to solve the above problems, an object of the present invention is a polarizing plate that has a low reflectivity in the oblique direction as well as the front direction of the screen and can exhibit a neutral color and an image display device comprising the same Is to provide

Another object of the present invention is to provide a polarizing plate having an orthogonal color value of -5 to -2, an absorbance of 700 nm wavelength of 1.5 or more, and an image display device including the same.

Another object of the present invention is to provide a polarizing plate having a total thickness direction phase difference (Rth) of -30 to 30nm and an image display device including the same.

On the other hand, the present invention is a polarizer for polarizing light; And a retardation film for retarding the phase of the light, wherein an orthogonal color value is -5 to -2, and an absorbance at a wavelength of 700 nm is 1.5 or more, and an image display device including the same is provided.

Preferably, the light transmittance of the polarizer is 44% or more, and the polarization degree is 98% or more.

On the other hand, the present invention is a polarizer for polarizing light; And it includes a retardation film for retarding the phase of the light, the total thickness direction phase difference (Rth) of the polarizing plate is -30 to 30nm provides a polarizing plate and an image display device comprising the same.

The polarizing plate may further include a positive C plate, and a λ / 4 retardation film may be used as the retardation film.

The polarizing plate and the image display device including the same according to the present invention exhibit low reflectance and neutral color in the oblique direction as well as in the front direction of the screen, and exhibit excellent reflected color without distortion of color in the oblique direction.

1 is a configuration diagram of a polarizing plate according to a first embodiment of the present invention.
2 is a configuration diagram of a polarizing plate according to a second embodiment of the present invention.
3 is a configuration diagram of a polarizing plate according to a third embodiment of the present invention.
4 is a configuration diagram of a polarizing plate according to a fourth embodiment of the present invention.
5 is a configuration diagram of a polarizing plate according to a fifth embodiment of the present invention.
6 is a configuration diagram of a polarizing plate according to a sixth embodiment of the present invention.

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

The polarizing plate according to the present invention may be configured by appropriately combining a polarizer, a protective film, a λ / 4 retardation film (1/4 wavelength retardation film), a 0 retardation film, a positive C plate, and the like. Before explaining the structure and manufacturing method of the polarizing plate according to the detailed description of the components constituting it.

< Polarizer >

The polarizer is exemplified by a conventional iodine-based polarizer in which iodine is adsorbed and oriented on a polymer film.

The polymer film for manufacturing the polarizer is not particularly limited as long as it is a dichroic material, that is, a film that can be dyed with iodine, specifically, a polyvinyl alcohol film, a partially gummed polyvinyl alcohol film; Hydrophilic polymer films such as polyethylene terephthalate films, ethylene-vinyl acetate copolymer films, ethylene-vinyl alcohol copolymer films, cellulose films, partially gummed films thereof, and the like; Or a polyene-oriented film such as a polyvinyl alcohol-based film dehydrated, a polyvinyl alcohol-based film treated with dehydrochloric acid, and the like. Among them, a polyvinyl alcohol-based film is preferable in that it not only has an excellent effect of enhancing the uniformity of polarization degree in plane, but also has excellent dyeing affinity for iodine.

The manufacturing method of the polarizer usually includes a swelling step, a dyeing step, a crosslinking step, a stretching step, a washing step, and a drying step, and is mainly classified by a stretching method. For example, a dry stretching method, a wet stretching method, or a hybrid stretching method in which the above two kinds of stretching methods are mixed and the like can be mentioned. Hereinafter, a method of manufacturing the polarizer of the present invention will be described using the wet stretching method as an example, but is not limited thereto. The remaining steps except the drying step among the above steps are performed in a state in which the polyvinyl alcohol-based film is immersed in a constant temperature water bath filled with one or more solutions selected from various types of solutions. In addition, the order and number of repetitions of each step are not particularly limited, and each step may be performed simultaneously or sequentially, and some steps may be omitted. For example, the stretching step may be performed before the dyeing step or after the dyeing step, or may be performed simultaneously with the swelling step or the dyeing step.

The swelling step is immersed in a swelling tank filled with an aqueous solution for swelling prior to dyeing the unstretched polyvinyl alcohol-based film, removing impurities such as dust or anti-blocking agents deposited on the surface of the polyvinyl alcohol-based film and removing polyvinyl alcohol. This is a step to improve the stretching efficiency by swelling the system film and to improve the physical properties of the polarizer by preventing dyeing non-uniformity.

As an aqueous solution for swelling, water (pure water, deionized water) can be used alone, and when a small amount of glycerin or potassium iodide is added thereto, swelling of the polymer film and workability can also be improved. It is preferable that the content of glycerin is 5% by weight or less and the content of potassium iodide is 10% by weight or less with respect to 100% by weight of the swelling aqueous solution.

The temperature of the swelling tank is preferably 20 to 45 ° C, more preferably 25 to 40 ° C.

The execution time of the swelling step (swelling time of the swelling tank) is preferably 180 seconds or less, and more preferably 90 seconds or less. When the immersion time is in the above range, it is possible to suppress excessive swelling and becoming saturated, preventing breakage due to softening of the polyvinyl alcohol-based film, and uniformly adsorbing iodine in the dyeing step to improve polarization. have.

The stretching step may be performed together with the swelling step, and the stretching ratio is preferably about 1.1 to 3.5 times.

The swelling step may be omitted, and swelling may be performed simultaneously in the dyeing step.

The dyeing step is a step of adsorbing iodine to the polyvinyl alcohol-based film by immersing the polyvinyl alcohol-based film in a dyeing tank filled with a dichroic material, for example, an aqueous solution for dyeing containing iodine.

The aqueous solution for dyeing may include water, a water-soluble organic solvent, or a mixed solvent and iodine. The content of iodine is preferably 0.4 to 400 mmol / L relative to 100% by weight of an aqueous solution for dyeing, more preferably 0.8 to 275 mmol / L, and most preferably 1 to 200 mmol / L. To further improve the dyeing efficiency, iodide may be further included as a dissolution aid. Potassium iodide, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. can be used alone or in combination of two or more. Of these, potassium iodide is preferred in view of its high solubility in water. The content of iodide is preferably 0.010 to 10% by weight, more preferably 0.100 to 5% by weight relative to 100% by weight of the aqueous solution for dyeing.

The temperature of the dyeing tank is preferably 5 to 42 ° C, more preferably 10 to 35 ° C. In addition, the immersion time of the polyvinyl alcohol-based film in the dyeing tank is not particularly limited, preferably 1 to 20 minutes, more preferably 2 to 10 minutes.

The stretching step may be performed together with the dyeing step, in which case the cumulative stretching ratio is preferably 1.1 to 4.0 times. In this specification, “cumulative stretching ratio” refers to the product of the stretching ratio at each step.

The present invention includes the step of immersing the polyvinyl alcohol-based film in an aqueous solution for crosslinking containing an acetate metal salt in the crosslinking step to improve color durability and optical properties of the polarizer. The crosslinking step is a step of fixing the adsorbed iodine molecule by immersing the dyed polyvinyl alcohol-based film in an aqueous solution for crosslinking so that the dyeability by the iodine molecule that is physically adsorbed is not lowered by the external environment. Dichroic dyes are not often eluted in a humid environment, but iodine molecules are often dissolved or sublimed depending on the environment when the crosslinking reaction is unstable, and sufficient crosslinking reaction is required. In addition, in order to improve the optical properties by aligning all polyvinyl alcohol molecules and iodine molecules located between the molecules, the crosslinking step is important because it must generally be stretched at the largest draw ratio in the crosslinking step.

The temperature of the crosslinking tank is 20 to 70 ° C, and the immersion time of the polyvinyl alcohol-based film in the crosslinking tank may be 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

The stretching step may be performed together with the crosslinking step, and in this case, it is preferable that the total cumulative stretching ratio is 3.0 to 8.0 times.

As described above, the stretching step may be performed together with the swelling step, the dyeing step, and the crosslinking step, and may also be performed as an independent stretching step using a separate stretching tank filled with an aqueous solution for stretching after the crosslinking step.

In the present invention, it is preferable to simultaneously perform the stretching step in the crosslinking step using the aqueous solution for crosslinking.

The water washing step is a step of removing unnecessary residues such as boric acid attached to the polyvinyl alcohol-based film in the previous steps by immersing the crosslinked and stretched polyvinyl alcohol-based film in a water washing tank filled with an aqueous washing solution.

The aqueous solution for washing with water may be water, and iodide may be further added thereto.

The temperature of the water bath is preferably 5 to 60 ° C, more preferably 5 to 20 ° C.

The washing step may be omitted, and may be performed whenever previous steps such as a dyeing step, a crosslinking step, or a stretching step are completed. Further, it may be repeated one or more times, and the number of repetitions is not particularly limited.

The drying step is a step of drying the washed polyvinyl alcohol-based film and further improving the orientation of the iodine molecule dyed by neck-in by drying to obtain a polarizer having excellent optical properties.

As a drying method, methods such as natural drying, air drying, heating drying, far infrared drying, microwave drying, hot air drying, etc. can be used. Recently, microwave drying in which only water in the film is activated and dried is newly used, and is usually hot air drying. Is mainly used. For example, hot air drying may be performed at 20 to 90 ° C. for 1 to 10 minutes. In addition, the drying temperature is preferably low to prevent deterioration of the polarizer, more preferably 80 ° C or less, and most preferably 60 ° C or less.

In addition, the present invention provides a polarizing plate is a protective film is laminated on at least one side of the polarizer manufactured by the above manufacturing method.

<Protective film>

The protective film is not particularly limited as long as it is a film having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropy, and the like.

Specifically, polyester-based resins such as polyethylene terephthalate, polyethylene isophthalate, and polybutylene terephthalate; Cellulose-based resins such as diacetyl cellulose and triacetyl cellulose; Polycarbonate-based resins; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based resins such as polyethylene, polypropylene, polyolefins having a cyclo-based or norbornene structure, and ethylene propylene copolymers; Vinyl chloride resin; Polyamide-based resins such as nylon and aromatic polyamides; Imide resin; Polyethersulfone-based resins; Sulfone resins; Polyether ketone-based resin: polyphenylene sulfide-based resin; Vinyl alcohol-based resins; Vinylidene chloride-based resins; Vinyl butyral resins; Allylate-based resins; Polyoxymethylene resins; And films composed of thermoplastic resins such as epoxy resins, and films composed of blends of the thermoplastic resins can also be used. Further, a film made of a thermosetting resin such as (meth) acrylic, urethane-based, epoxy-based, silicone-based, or ultraviolet-curable resin may be used. Among these, a cellulose-based film having a surface saponified (sagified) with an alkali or the like is preferable in consideration of polarization characteristics or durability. In addition, the protective film may have a function of an optical layer.

< Phase difference  Film>

The λ / 4 retardation film (1/4 wavelength retardation film) can be obtained, for example, by orienting the polymer film in a uniaxial direction, biaxial direction, or other suitable method, and serves to prevent reflected light.

The type of the polymer compound constituting the polymer film is not particularly limited. In this case, it is preferable to use a polymer compound having high transparency to be suitable for use in an image display device, and these compounds are polycarbonate compounds, polyester compounds, polysulfone compounds, polyether sulfone compounds, polystyrene compounds , Polyolefin compounds, polyvinyl alcohol compounds, cellulose acetate compounds, polymethyl methacrylate compounds, polyvinyl chloride compounds, polyacrylate polyvinyl chloride compounds, polyamide polyvinyl chloride compounds, and the like.

Alternatively, the λ / 4 retardation film may be made of nematic or smectic, preferably nematic liquid crystal material, which is polymerizable by in situ polymerization. As a specific example, it may be prepared by coating a polymerizable liquid crystal material on a substrate, orienting it in a planar orientation, and continuously polymerizing it by exposure to heat or ultraviolet rays.

The lambda / 4 phase difference film according to the polarizing plate of the present invention has a reverse wavelength dispersion. The Ro (450) / Ro (550) value may be 0.83 or more and less than 0.99, and the Ro (630) / Ro (550) value may be 1 or more and 1.05 or less. Here, Ro (450), Ro (550), and Ro (630) are front phase difference values for wavelengths of 450nm, 550nm, and 630nm, respectively. The λ / 4 retardation film according to the present invention may have various retardation values. For example, the thickness direction phase difference value (Rth) may be 40 to 180 nm, and the front phase difference value (Ro) may be 130 to 150 nm.

<Amount ( positive A) C plate>

When only the λ / 4 retardation film is introduced, there may be a tendency that the reflectance characteristics in the oblique direction (the direction viewed from the top, bottom, left, and right of the front side of the viewer side of the screen) deteriorate.

Accordingly, the polarizing plate according to the present invention further includes a positive C plate layer, and improves the reflection color in the oblique direction, thereby improving image quality.

The amount of C plate layer according to the present invention can be produced by orienting a polymer film in an appropriate manner, or by coating a polymerizable cholesteric liquid crystal compound on one surface of a substrate and aligning it in a certain direction, followed by curing.

When a polymerizable cholesteric liquid crystal compound is used, a zero phase difference film can be used as the substrate. In the present invention, the zero phase difference film refers to a film in which no substantial phase difference occurs even when light is transmitted.

The positive C plate layer according to the present invention ideally includes a case where the refractive index ratio Nz is negative infinity, but substantially less than -6 as described above. Accordingly, the thickness direction phase difference value Rth and the front phase phase difference value Ro of the positive C plate layer may have various values within a range that satisfies the range of the total refractive index ratio of the polarizing plate of the present invention. For example, the thickness direction phase difference value Rth may be -190 to -10 nm. If the thickness direction phase difference value is less than -190 nm or more than -10 nm, the effect of improving the reflection color may be insignificant. In addition, the front phase difference value Ro should ideally be 0 nm, but is included in the present invention to the extent that it can be seen as substantially 0 nm. For example, the front phase difference value Ro may be -1 to 1 nm.

<Polarizing plate>

Hereinafter, a polarizing plate according to the present invention will be described in detail with reference to FIGS. 1 to 5.

The polarizing plate according to the present invention has a polarizer and a λ / 4 retardation film and a positive C plate layer under it, and is implemented such that the total thickness direction phase difference (Rth) is −30 to 30 nm. This is because if the total thickness direction phase difference Rth is less than -30 nm or more than 30 nm, the change in reflection color according to the viewing angle may increase, and visibility may be deteriorated.

The polarizing plate according to the present invention preferably includes a polarizer, a λ / 4 retardation film and a positive C plate layer, and the retardation values of each layer are various values within a range that satisfies the range of the total thickness direction phase difference (Rth). Can have Examples of the retardation values of the λ / 4 retardation film and the positive C plate layer are as described above. In addition, when a 0 retardation film is further used as a protective film of a polarizer or a substrate of a positive C plate layer, a polarizer, a λ / 4 retardation film, and a positive C plate in consideration of the retardation value or the retardation value of the protective film or the 0 retardation film The phase difference value of the layer is appropriately adjusted to satisfy the above range of the total refractive index ratio of the polarizing plate. Therefore, the above-described range of retardation values of each layer is a preferred example for each layer. Since the total refractive index ratio is obtained from the entire structure in which each layer is stacked, the illustrated retardation values for each layer are subdivided according to specific cases. Can be applied.

For example, when the thickness direction phase difference value of the λ / 4 phase difference film is 40 nm or more and less than 65 nm, the thickness direction phase difference value of the positive C plate layer is preferably -85 nm to -60 nm.

In addition, when the thickness direction phase difference value of the λ / 4 phase difference film is 65 nm or more and less than 80 nm, the thickness direction phase difference value of the positive C plate layer is preferably -100 nm to -85 nm or less,

When the thickness direction phase difference value of the λ / 4 retardation film is 80 nm or more and less than 100 nm, the thickness direction phase difference value of the positive C plate layer is preferably -120 nm to -100 nm,

When the thickness direction phase difference value of the λ / 4 phase difference film is 100 nm or more and 180 nm or less, the thickness direction phase difference value of the positive C plate layer is preferably -200 nm to -120 nm.

1 is a configuration diagram of a polarizing plate according to a first embodiment of the present invention.

Referring to FIG. 1, the polarizing plate 100 according to the first embodiment of the present invention includes a polarizer 120, protective films 110 and 115 laminated on both sides of the polarizer 120, and the protective film 115. It includes a lambda / 4 phase difference film 130 to be laminated, a positive (positive) C plate 140 is laminated to the lambda / 4 phase difference film 130. In addition, the polarizing plate 100 configured as described above may be attached to an image display device (not shown) or the reflective layer 10 (eg, a cathode of an organic light emitting diode (OLED)).

2 is a configuration diagram of a polarizing plate according to a second embodiment of the present invention. For reference, the second embodiment of the present invention is a structure in which the protective film under the polarizing plate is omitted compared to the first embodiment.

Referring to FIG. 2, the polarizing plate 200 according to the second embodiment of the present invention is a polarizer 220, a protective film 210 laminated on one surface of the polarizer 120, and a laminate on the other surface of the polarizer 120. The lambda / 4 phase difference film 230, and includes a positive (positive) C plate 240 stacked on the lambda / 4 phase difference film 230. Further, the polarizing plate 200 configured as described above may be attached to an image display device (not shown) or the reflective layer 20 (eg, a cathode of an organic light emitting diode (OLED)).

3 is a configuration diagram of a polarizing plate according to a third embodiment of the present invention. For reference, the third embodiment of the present invention is a structure in which the stacking order of the λ / 4 phase difference film and the positive C plate is changed compared to the first embodiment.

Referring to FIG. 3, the polarizing plate 300 according to the third embodiment of the present invention includes a polarizer 320, protective films 310 and 315 that are respectively laminated on both sides of the polarizer 320, and the protective film 315. It includes a positive (positive) C plate 340, the positive (positive) C plate 340 is laminated on the lambda / 4 phase difference film 330. The polarizing plate 300 configured as described above may be attached to an image display device (not shown) or the reflective layer 30 (eg, a cathode of an organic light emitting diode (OLED)).

4 and 5 are configuration diagrams of polarizing plates according to the fourth and fifth embodiments of the present invention. For reference, the fourth and fifth embodiments of the present invention is a case where a zero phase difference film is further provided on one surface of a positive C plate layer as compared with the first embodiment. For reference, when the positive C plate layer is formed by polymerization of a polymerizable liquid crystal compound, a zero phase difference film is used as a substrate of the polymerizable liquid crystal compound.

Referring to FIG. 4, the polarizing plate 400 according to the fourth embodiment of the present invention includes a polarizer 420, protective films 410 and 415 stacked on both sides of the polarizer 420, and the protective film 415, respectively. A lambda / 4 phase difference film 430, which is laminated, and a positive C plate 440 using the 0 phase difference film 450 as a substrate is laminated on the lambda / 4 phase difference film 430, but the 0 phase difference The film 450 is laminated so as to face the λ / 4 retardation film 430. In addition, the polarizing plate 400 configured as described above may be attached to an image display device (not shown) or the reflective layer 40 (eg, a cathode of an organic light emitting diode (OLED)).

In addition, referring to FIG. 5, the polarizing plate 500 according to the fifth embodiment of the present invention includes a polarizer 520, protective films 510 and 515 laminated on both sides of the polarizer 520, and the protective film ( 515) includes a λ / 4 retardation film 530, and a positive C plate 540 having a 0 retardation film 550 as a substrate is stacked on the λ / 4 retardation film 530. A positive C plate 540 is stacked to face the λ / 4 retardation film 530. In addition, the polarizing plate 500 configured as described above may be attached to an image display device (not shown) or the reflective layer 50 (eg, a cathode of an organic light emitting diode (OLED)).

6 is a configuration diagram of a polarizing plate according to a sixth embodiment of the present invention.

Referring to FIG. 6, the polarizing plate 600 according to the sixth embodiment of the present invention is a polarizer 620, a protective film 610 laminated on one surface of the polarizer 620, and a laminate on the other surface of the polarizer 620. The zero phase difference film 650 and the positive C plate 640, the pressure-sensitive adhesive 660 laminated on the positive C plate 640, the λ / 4 phase difference film 630 laminated on the pressure-sensitive adhesive 660, the and a pressure-sensitive adhesive 665 laminated on the λ / 4 retardation film 630.

Hereinafter, an experiment in which optical characteristics and reflection characteristics are measured using the polarizing plate according to the sixth embodiment of the present invention as a model will be described.

Example  One

A polyvinyl alcohol film (VF-PS, KURARAY) with a thickness of 75 µm having an average polymerization degree of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched 6 times, and 60? Of water (deionized water) was maintained. ), And then immersed in an aqueous solution at 28 ° C. having a weight ratio of iodine / potassium iodide / water of 0.013 / 5/100 for 60 seconds. Thereafter, the solution was immersed in an aqueous solution at 55 ° C with a weight ratio of potassium iodide / boric acid / water of 13/10/100 for 300 seconds. Subsequently, after washing with water at 10 ° C. for 5 seconds and drying at 45 ° C. for 4 minutes, a polarizer in which iodine was adsorbed and oriented in a polyvinyl alcohol resin was prepared. As a protective film on one surface of the polarizer, a zero phase difference film coated with a positive C plate layer having a thickness direction phase difference of -92.5 nm and a TAC film was attached using an adhesive. After forming an adhesive on the positive C plate layer, an in-plane phase difference 141 nm having a reverse wavelength dispersion property and a thickness direction phase difference 72.5 nm λ / 4 phase difference film were bonded. Thereafter, an adhesive was formed on the λ / 4 retardation film to complete the polarizing plate.

Example  2

In the polarizing plate preparation example, the polarizing plate was produced in the same manner except that after immersing in an aqueous solution at 28 ° C for an iodine / potassium iodide / water ratio of 0.012 / 5/100 for 60 seconds, and washing with water at 10 ° C for 7 seconds.

Example  3

A polarizing plate was prepared in the same manner as in Example 1, but no positive C plate layer was attached.

Example  4

A polarizing plate was prepared in the same manner as in Example 1, but a λ / 4 retardation film having a thickness direction phase difference of 52.5 nm and a positive C plate layer having a thickness direction phase difference of -72.5 nm were applied.

Example  5

A polarizing plate was manufactured in the same manner as in Example 1, but a lambda / 4 phase difference film having a thickness direction phase difference of 90 nm and a positive C plate layer having a thickness direction phase difference of -110 nm were applied.

Example  6

A polarizing plate was manufactured in the same manner as in Example 1, but a λ / 4 phase difference film having a thickness direction phase difference of 140 nm and a positive C plate layer having a thickness direction phase difference of -160 nm were applied.

Comparative example  One

In the polarizing plate preparation example, the polarizing plate was produced in the same manner, except that the iodine / potassium iodide / water weight ratio of 0.011 / 5/100 was immersed in an aqueous solution at 28 ° C for 60 seconds and washed with water at 10 ° C for 9 seconds.

Comparative example  2

In the polarizing plate preparation example, the polarizing plate was produced in the same manner, except that the iodine / potassium iodide / water weight ratio of 0.010 / 5/100 was immersed in an aqueous solution at 28 ° C for 60 seconds and washed with water at 10 ° C for 10 seconds.

Comparative example  3

In the polarizing plate preparation example, the polarizing plate was produced in the same manner, except that the weight ratio of iodine / potassium iodide / water was immersed in an aqueous solution at 28 ° C for 0.010 / 5/100 for 60 seconds, and washed for 20 seconds with water at 10 ° C.

Comparative example  4

In the polarizing plate preparation example, the polarizing plate was produced in the same manner, except that the iodine / potassium iodide / water weight ratio of 0.010 / 5/100 was immersed in an aqueous solution at 28 ° C for 60 seconds and washed with water at 10 ° C for 30 seconds.

Comparative example  5

In the polarizing plate preparation example, a polarizing plate was produced in the same manner except that after immersing in an aqueous solution at 28 ° C. having a weight ratio of iodine / potassium iodide / water of 0.013 / 5/100 for 60 seconds and washing with water at 10 ° C. for 1 second.

Comparative example  6

A polarizing plate was prepared in the same manner as in Example 1, but a positive C plate layer having a phase difference of -160 nm in the thickness direction was applied.

Comparative Example 7

A polarizing plate was manufactured in the same manner as in Example 1, but a λ / 4 phase difference film having a thickness direction phase difference of 52.5 nm and a positive C plate layer having a thickness direction phase difference of -160 nm were applied.

Comparative Example 8

A polarizing plate was manufactured in the same manner as in Example 1, but a λ / 4 phase difference film having a thickness direction phase difference of 90 nm and a positive C plate layer having a thickness direction phase difference of -160 nm were applied.

Experimental Example

1. Measurement of optical properties

Cut the prepared polarizer to a size of 4 cm × 4 cm to prepare a specimen, attach the specimen to a measurement holder, and then use a UV-visible spectrometer (V-7100, manufactured by JASCO) to measure the unit transmittance (Ty) and polarization. Figure (P), orthogonal color value (orthogonal b *), absorbance at 700 nm wavelength (A700) were measured. In this case, the simple substance transmittance, the polarization degree, and the absorbance (A700) at a wavelength of 700 nm are defined by Equations 1 to 3 below.

[Equation 1]

Group transmittance (Ty) = (T1 + T2) / 2

Here, T1 is the parallel transmittance obtained when the pair of polarizers are arranged in parallel with the absorption axis, and T2 is the orthogonal transmittance obtained when the pair of polarizers is arranged in the state where the absorption axis is orthogonal.

[Equation 2]

Polarization (P) = [(T1-T2) / (T1 + T2)] / 2

Here, T1 is the parallel transmittance obtained when the pair of polarizers are arranged in parallel with the absorption axis, and T2 is the orthogonal transmittance obtained when the pair of polarizers is arranged in the state where the absorption axis is orthogonal.

[Equation 3]

A700 =-Log10 {[TMD (700) × TTD (700)] / 10000}

Here, the TMD 700 is a parallel transmittance at a wavelength of 700 nm obtained when a pair of polarizers are arranged in parallel with the absorption axis, and the TTD 700 is a pair of polarizers arranged in a state in which the absorption axes are orthogonal. Orthogonal transmittance at a wavelength of 700 nm obtained.

2. Measurement of reflection characteristics

A simulation (Techwiz LCD 1D) was performed from the result of the optical properties of the polarizing plate measured in Experimental Example 1 and the refractive index of the λ / 4 phase difference film and the positive C plate layer, and the front reflection and the inclination angle θ = 60 ° and the azimuth angle of Φ = 45 ° The color difference components a * and b * of CIELAB coordinates were obtained from the slope reflection.

3. Experimental results

On the other hand, the polarizing plate according to the present invention is a display device (image display device), specifically TN (twisted nematic), HTN (very twisted nematic) or STN (excessively twisted nematic) mode display, AMD-TN (active Matrix derived TN) display, IPS (plane switching) mode display, DAP (aligned phase transformation) or VA (vertical aligned) mode display, such as ECB (electrically controlled birefringence), CSH (color super homeotropic) , VAN or VAC (vertical aligned nematic or cholesteric) displays, MVA (multi-domain vertically aligned) displays, bending mode displays or hybrid displays such as OCB (optical compensated bending cells or optically compensated) Birefringence), R-OCB (reflective OCB), HAN (hybrid ordered nematic) or pi-cell display or organic light emitting diode (OLED).

The polarizing plate according to the present invention can be particularly preferably used to improve light to antireflection properties in organic light emitting diodes (OLEDs), reflective or transmissive LCDs. For example, it is disposed on the cathode (reflection layer) of the organic light emitting diode (OLED) and can be used to maintain excellent reflection color in the oblique direction while simultaneously reducing the reflectance of the front and the slope of the incident light to the panel.

Other configurations of an image display device such as an organic light emitting diode (OLED), a liquid crystal display (LCD), except that the polarizing plate according to the present invention is used in a conventional polarizing plate position, can adopt the conventional general configuration as it is.

As described above, the present invention has been described in detail with reference to embodiments of the present invention. For those skilled in the art to which the present invention pertains, this specific technology is only a preferred embodiment, and thus the scope of the present invention is limited. It is obvious that it is not. For example, when the polarizing plate of the present invention is disposed in the order of a polarizer, a half-wavelength film on the lower portion, and a quarter-wavelength film on the lower portion, a transparent protective film, an additional retardation plate, a hard coating layer, a touch panel, etc. are disposed on the polarizer. Can be.

Therefore, those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents, and thus, the practical scope of the present invention and the appended claims. It is said to be defined by his equivalent.

100, 200, 300, 400, 500, 600: Polarizer
120, 220, 320, 420, 520, 620: polarizer
130, 230, 330, 430, 530, 630: λ / 4 retardation film
140, 240, 340, 440, 540, 640: positive C plate
450, 550, 650: 0 retardation film

Claims (14)

A polarizer that polarizes light;
A retardation film retarding the phase of the light; And
A polarizing plate comprising a positive C plate,
The retardation film is a 1/4 wavelength retardation film having reverse wavelength dispersion,
The orthogonal color value of the polarizing plate is -5 to -2, the absorbance at a wavelength of 700nm is 1.5 to 1.84,
The total thickness direction phase difference (Rth) of the polarizing plate is -30 to 30nm OLED polarizing plate. According to claim 1,
The polarizer of the polarizer is 44% or more, and the polarization degree is 98% or more, characterized in that the polarizing plate for OLED. delete delete According to claim 1,
The polarizing plate includes a polarizer, a retardation film, and a positive C plate; Or a polarizer, a positive C plate, a polarizing plate for OLED, characterized in that laminated in the order of the retardation film. The method of claim 5,
The positive C plate is formed by polymerization of a polymerizable liquid crystal compound, and a zero phase difference film is provided on one surface of the positive C plate as a substrate of the polymerizable liquid crystal compound. delete delete According to claim 1,
The thickness direction phase difference of the retardation film is 40nm to 65nm, the thickness direction phase difference of the positive C plate is -85nm to -60nm, characterized in that the polarizing plate for OLED. According to claim 1,
The thickness direction phase difference of the retardation film is 65 nm to 80 nm, and the thickness direction phase difference of the positive C plate is -100 nm to -85 nm. According to claim 1,
The thickness direction phase difference of the retardation film is 80nm to 100nm, the thickness direction phase difference of the positive C plate is -120nm to -100nm, characterized in that the polarizing plate for OLED. According to claim 1,
The thickness direction phase difference of the retardation film is 100nm to 180nm, the thickness direction phase difference of the positive C plate is -200nm to -120nm, characterized in that the polarizing plate for OLED. delete An image display device comprising the polarizing plate for OLEDs according to any one of claims 1, 2, 5, 6 and 9 to 12.

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