KR20160081138A - Protective film, polarizer and display device comprising same - Google Patents

Abstract

The present invention relates to a protective film, a polarizer, and a display device. According to the present invention, a protective film for a polarizing plate has excellent heat resistant properties and hydrolysis resistant properties, does not have a rainbow spot or the like shown therein, and has improved optical properties. The protective film for a polarizing plate comprises first and second polyester layers.

Description

TECHNICAL FIELD [0001] The present invention relates to a protective film, a polarizer, and a display device including the polarizer.

More particularly, the present invention relates to a protective film for a polarizing plate having heat resistance and hydrolysis resistance and having no iridescence, a polarizing plate including the polarizing plate, and a display device including the same.

Various displays such as a liquid crystal display (LCD), a plasma display panel (PDP), and an electrophoretic display (ELD) have been developed or commercialized in the information society. Indoor display displays are becoming larger and thinner, Outdoor portable displays are becoming smaller and lighter. In order to further improve the function of such a display, various optical films have been used since early.

The material used for the optical film has properties such as high transmittance, optical isotropy, defect-free surface, high heat resistance and moisture resistance, high flexibility, high surface hardness, low shrinkage, .

Generally, as a protective film for protecting a polarizer of a polyvinyl alcohol material, a triacetylcellulose (TAC) film having properties such as high transmittance, optical isotropy, and defect-free surface is used on one side or both sides of a polarizer. However, the triacetyl cellulose film is disadvantageous in that it is expensive, its supply source is not various, and it is vulnerable to moisture.

Accordingly, protective films of various materials capable of replacing triacetyl cellulose films have been recently developed. For example, cycloolefin polymer (COP), acryl, polyester film, etc. are used singly or in combination A method was proposed. As a result, Japanese Patent Publication No. 4962661 discloses a technique in which a polyester film is stretched four times or more in the transverse direction (tenter direction) to be used as a polarizer protective film, but there is a problem such as nonuniform stretching in width / length direction , It is required to modify the phase such that the retardation is expressed by adding the widthwise stretching as the thickness becomes thin, and there is a limitation in thinning.

DISCLOSURE OF THE INVENTION The present inventors have conducted extensive research to solve the problems of the prior art described above. As a result, they have found a protective film that is superior in heat resistance and hydrolysis resistance to conventional materials, and has no rainbow stains.

Japanese Patent Publication No. 4962661

Accordingly, it is an object of the present invention to provide a protective film for a polarizing plate which is excellent in heat resistance and hydrolysis resistance, and has no iridescence, a polarizing plate including the protective film, and a display device including the same.

According to one embodiment,

A first polyester layer comprising a first polyester resin; And

A second polyester layer disposed on the first polyester layer and comprising a second polyester resin,

Wherein the refractive index of the first polyester resin is 1.60 or more,

The refractive index of the second polyester resin is 1.56 or less,

Plane retardation of 150 nm or less,

The retardation in the thickness direction is 2400 nm or less,

And a heat shrinkage of not more than 3% based on the longitudinal direction and the width direction when the film is heat-treated at a temperature of 80 캜 for 4 hours.

According to one embodiment,

A polarizer layer; And

And a protective film for the polarizing plate adjacent to at least one of the upper surface and the lower surface of the polarizer layer.

According to one embodiment,

Display panel; And

And the polarizing plate disposed on at least one of the upper surface and the lower surface of the display panel.

The protective film according to the embodiment includes a first polyester layer and a second polyester layer in a laminated form, and has a small in-plane retardation and a small thickness retardation. Therefore, the protective film is excellent in heat resistance and hydrolysis resistance, and iridescent stains are not observed when viewed from above, and the protective film has improved optical properties, and thus can be usefully used as a protective film for a polarizing plate.

1 is a cross-sectional view showing a cross section of a protective film for a polarizing plate according to an embodiment.
2 is a cross-sectional view illustrating a polarizing plate according to one embodiment.
3 is a schematic view showing a liquid crystal display device.
4 is a schematic view showing an organic light emitting display device.

In the description of the embodiments, in the case where each film, film, panel or layer is described as being formed "on" or "under" of each film, film, panel, , "On" and "under" all include being formed "directly" or "indirectly" through "another element". In addition, the upper and lower standards for each component are described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

1 is a cross-sectional view showing a cross section of a protective film for a polarizing plate according to an embodiment. 2 is a cross-sectional view illustrating a polarizing plate according to one embodiment.

Referring to FIGS. 1 and 2, a polarizing plate according to an embodiment includes a polarizer layer and a pair of protective films.

The protective films include a polyester resin. That is, all of the protective films may include a polyester resin. Alternatively, one of the protective films may include a polyester resin, and the other may include an acrylic resin or a triacetylcellulose resin.

As shown in FIG. 1, the protective film may have a laminated structure of two or more layers. The protective film 320 includes a first polyester layer 321, a second polyester layer 322, and a third polyester layer 323.

The second polyester layer 322 is disposed on the first polyester layer 321. More specifically, the second polyester layer 322 may be disposed directly adjacent to the first polyester layer 321. More specifically, the second polyester layer 322 may be disposed directly on the upper surface of the first polyester layer 321. More specifically, the second polyester layer 322 may be in direct contact with the upper surface of the first polyester layer 321.

The third polyester layer 323 is disposed under the first polyester layer 321. More specifically, the third polyester layer 323 may be disposed directly adjacent to the first polyester layer 321. More specifically, the third polyester layer 323 may be disposed directly on the lower surface of the first polyester layer 321. More specifically, the third polyester layer 323 may be in direct contact with the lower surface of the first polyester layer 321.

The first polyester layer, the second polyester layer, and the third polyester layer may be extruded and stretched simultaneously by a co-extrusion process.

Although the protective film according to the present embodiment has been described as a three-layer structure, it is not limited thereto. That is, the third polyester layer is omitted, and the protective film may have a two-layer structure. Further, the protective film may further include an additional layer, and may have a layer structure of four or more layers.

As shown in FIG. 2, the polarizing plate 11 according to the present embodiment may include the polarizer layer 220 and the protective films 320 and 310 adjacent to at least one of the upper and lower surfaces.

The polarizer layer 220 performs a polarization function. The polarizer layer 220 may be a polyvinyl alcohol layer stained with iodine or the like. At this time, the polyvinyl alcohol molecules contained in the polyvinyl alcohol layer may be aligned in one direction.

The protective film for a polarizing plate according to an embodiment is characterized in that the first polyester resin is polyethylene terephthalate and the second polyester resin comprises (i) 5 to 50 mol%, based on the total amount of the diol component, of diol containing spiroglycol Component and (ii) a dicarboxylic acid component.

The protective film for a polarizing plate according to an embodiment may further include a third polyester layer in which the protective film for polarizing plate is disposed under the first polyester layer, the third polyester layer includes a third polyester resin Wherein the first polyester resin comprises (i) a diol component comprising 5 to 50 mol% of spiroglycol, and (ii) a dicarboxylic acid component, based on the total amount of the diol component, wherein the second polyester resin And the third polyester resin comprises polyethylene terephthalate, and the ratio of the sum of the thicknesses of the second polyester layer and the third polyester layer to the thickness of the first polyester layer is from 1: 5 to 5: 1 Lt; / RTI >

Further, in the protective film for a polarizing plate according to the embodiment, the protective film for polarizing plate may further comprise a third polyester layer disposed under the first polyester layer, and the third polyester layer may comprise a third polyester resin Wherein the second polyester resin and the third polyester resin comprise (i) a diol component comprising 5 to 50 mole percent spiroglycol based on the total amount of the diol component, and (ii) a dicarboxylic acid component Wherein the first polyester resin comprises polyethylene terephthalate and the ratio of the sum of the thicknesses of the second polyester layer and the third polyester layer to the thickness of the first polyester layer is from 1: : May be one.

The first polyester layer comprises a first polyester. More specifically, the first polyester layer comprises the first polyester as a main component. More specifically, the first polyester layer may comprise 80 wt% or more of the first polyester. More specifically, the first polyester layer may comprise 90 wt% or more of the first polyester. More specifically, the first polyester layer may comprise 95 wt% or more of the first polyester. More specifically, the first polyester layer may comprise 99 wt% or more of the first polyester.

And the second polyester layer comprises a second polyester. More specifically, the second polyester layer comprises the second polyester as a main component. More specifically, the second polyester layer may comprise 80 wt% or more of the second polyester. More specifically, the second polyester layer may comprise 90 wt% or more of the second polyester. More specifically, the second polyester layer may comprise at least 95 wt% of the second polyester. More specifically, the second polyester layer may comprise 99 wt% or more of the second polyester.

And the third polyester layer comprises a third polyester. More specifically, the third polyester layer comprises the third polyester as a main component. More specifically, the third polyester layer may comprise 80 wt% or more of the third polyester. More specifically, the third polyester layer may comprise 90 wt% or more of the third polyester. More specifically, the third polyester layer may contain at least 95 wt% of the third polyester. More specifically, the third polyester layer may contain 99 wt% or more of the third polyester.

The first polyester may be a homopolymerized polyester. More specifically, the first polyester may be polyethylene terephthalate. The first polyester may be formed by polymerizing after transesterification of 95 mol% or more of ethylene glycol and 95 mol% or more of terephthalic acid.

The second polyester and the third polyester may be copolymerized polyesters. More specifically, the second polyester and the third polyester may be copolyester containing spiroglycol as a diol component.

The copolymer polyester includes a diol component and a dicarboxylic acid component. More specifically, the copolymer polyester may be formed by transesterifying the diol component and the dicarboxylic acid component, followed by polymerization.

The diol component of the copolyester includes spiroglycol. The spiroglycol may have a structure represented by the following formula (1). More specifically, the diol component may comprise from 5 to 50 mole percent of spiroglycols. More specifically, the diol component may comprise 20 to 45 mole percent of spiroglycols.

Alternatively, the diol component of the copolymerized polyester may comprise 1,4-cyclohexanedimethanol. More specifically, the diol component may comprise from 5 to 45 mole percent 1,4-cyclohexane dimethanol. More specifically, the diol component may comprise from 20 to 40 mol% 1,4-cyclohexanedimethanol.

Examples of the diol component that can be further used in addition to the spiroglycol include ethylene glycol, 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, 2,3- Butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) Diethylene-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1-dimethyl- And mixtures thereof. More specifically, the diol component may comprise about 60 to 95 mole percent ethylene glycol. More specifically, the diol component may comprise from about 65 to about 85 mole percent ethylene glycol.

The dicarboxylic acid component may be an aromatic dicarboxylic acid such as terephthalic acid, dimethylterephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and orthophthalic acid; Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and decanedicarboxylic acid; Alicyclic dicarboxylic acid; And their esterified products can be used alone or in combination of two or more. More specifically, the dicarboxylic acid component may comprise at least about 80 mole% aromatic dicarboxylic acid. More specifically, the dicarboxylic acid component may comprise at least about 80 mole percent terephthalic acid. More specifically, the dicarboxylic acid component may comprise at least about 90 mole percent terephthalic acid. More specifically, the dicarboxylic acid component may comprise at least about 99 mole% terephthalic acid.

Alternatively, the first polyester may be a co-polyester, and the second polyester and the third polyester may be homopolymeric polyesters.

Further, a part of the polyester layers may be formed of a homopolymerized polyester, and another part of the polyester layers may be formed of a copolymerized polyester. For example, the first polyester layer may be formed of a homopolymerized polyester, and the second polyester layer and the third polyester layer may be formed of a co-polyester. Alternatively, the first polyester layer may be formed of a copolymerized polyester, and the second polyester layer and the third polyester layer may be formed of a homopolymerized polyester.

At this time, the ratio of the sum of the thicknesses of the layers formed of the homopolymerized polyester and the sum of the thicknesses of the layers formed of the copolymerizable polyester may be 1: 5 to 5: 1. More specifically, the ratio of the sum of the thicknesses of the layers formed of the homopolymerized polyester to the sum of the thicknesses of the layers formed of the co-polyester may be 1: 3 to 2: 3.

The first polyester resin may have a refractive index different from that of the second polyester resin and the third polyester resin.

For example, the first polyester resin may have a relatively high refractive index, and the second polyester resin and the third polyester resin may have a relatively low refractive index. That is, the first polyester resin may have a refractive index of about 1.60 or more, more specifically about 1.62 or more, more specifically about 1.64 or more, and the second polyester resin and the third polyester resin may have a refractive index of about 1.56 or less, More specifically, it may have a refractive index of about 1.52 or less, more specifically about 1.50 or less.

Alternatively, the first polyester resin may have a relatively low refractive index, and the second polyester resin and the third polyester resin may have a relatively high refractive index. That is, the first polyester resin may have a refractive index of about 1.56 or less, more specifically about 1.52 or less, more specifically about 1.50 or less, and the second polyester resin and the third polyester resin may have a refractive index of about 1.60 or more , More specifically, at least about 1.62, and more specifically at least about 1.64.

The thickness of the protective film may be about 5 탆 to about 70 탆. More specifically, the thickness of the protective film may be from about 10 탆 to about 60 탆. More specifically, the thickness of the protective film may be from about 10 탆 to about 35 탆.

The transmittance of the protective film may be 80% or more. More specifically, the transmittance of the protective film may be 85% or more. More specifically, the transmittance of the protective film may be 90% or more. More specifically, the transmittance of the protective film may be 92% or more.

The haze of the protective film may be about 10% or less. More specifically, the haze of the protective film may be about 5% or less. More specifically, the haze of the protective film may be about 2% or less.

The in-plane retardation Ro of the protective film may be about 300 nm or less, more specifically 200 nm or less, more specifically 100 nm or less. More specifically, the in-plane retardation of the protective film may be about 1 nm to about 300 nm. More specifically, the in-plane retardation of the protective film may be about 1 nm to about 200 nm. More specifically, the in-plane retardation of the protective film may be about 1 nm to about 100 nm.

The thickness direction retardation (Rth) of the protective film may be about 2400 nm or less, more specifically, 2000 nm or less, more specifically, 1200 nm or less. More specifically, the retardation in the thickness direction of the protective film may be about 1 nm to about 2400 nm. More specifically, it can be from about 1 nm to about 2000 nm, and more specifically, from about 1 nm to about 1200 nm.

The protective film may satisfy the following formula (1).

≪ Formula 1 >

10? Rth / Ro? 20

Here, Rth is the retardation in the thickness direction of the protective film, and Ro is the in-plane retardation of the protective film.

More specifically, Rth / Ro may be from 11 to 18. More specifically, Rth / Ro may be 11.5 to 17.5.

Further, the protective film may be a film which is further stretched in the width direction (tenter direction) than the longitudinal direction (machine direction). More specifically, the protective film may be a film stretched from about 2 times to about 6 times in the longitudinal direction and from about 2 times to about 6 times in the width direction. More specifically, the protective film is a film stretched from about 2.5 to about 4.5 times or about 2.5 to about 4 times in the longitudinal direction and about 2.5 to about 4.5 times or about 2.5 to about 4 times in the transverse direction .

When the protective film is heat-treated at a temperature of about 80 캜 for about 4 hours, the heat shrinkage in the longitudinal direction and the width direction is 3% or less, more specifically 1% or less, more specifically 0.5% or less.

The protective film may further include an ultraviolet absorber such as a benzotriazole-based ultraviolet absorber, a penzophenone-based ultraviolet absorber, or an acrylonitrile-based ultraviolet absorber.

Further, the protective film may be subjected to a corona treatment, a coating treatment, a flame treatment, or the like in order to improve the adhesion with the polarizer layer.

Further, in order to improve the adhesiveness with the polarizer layer, the adhesive layer comprising at least one of polyester resin, polyurethane resin or polyacrylic resin as a main component may be formed on one side or both sides of the protective film.

The term " main component " refers to a component that is at least 50 wt% of the solid components constituting the adhesive layer. The coating liquid used for forming the adhesive layer is preferably an aqueous coating liquid containing at least one of a water-soluble or water-dispersible copolymer polyester resin, an acrylic resin and a polyurethane resin. The aqueous coating solution may be a water-soluble or water-dispersible copolymer polyester resin solution, an acrylic resin solution, or a polyurethane resin solution.

Since the protective film contains a polyester resin containing a high content of 1,4-cyclohexane dimethanol (CHDM), it can have high transmittance, high hydrolysis resistance and high heat resistance.

The layer containing the copolymerized polyester may have a low refractive index, and the layer containing the homopolymerized polyester may have a high refractive index. For example, the layer containing the copolymerized polyester may have a refractive index of 1.56 or less, and the layer containing the homopolymerized polyester may have a refractive index of 1.60 or more.

As described above, the protective film according to this embodiment includes a polyester layer having a high refractive index and a polyester layer having a low refractive index.

Accordingly, the polyester layer having a high refractive index reduces the heat shrinkage ratio, and the polyester layer having a low refractive index reduces the in-plane retardation and the thickness direction retardation.

That is, the protective film includes a polyester layer having different characteristics, and has an in-plane retardation of about 300 nm or less and a thickness retardation of about 2400 nm or less. More specifically, the protective film has an in-plane retardation of about 200 nm or less and a thickness direction retardation of about 2000 nm or less. More specifically, the protective film has an in-plane retardation of about 100 nm or less and a thickness direction retardation of about 1200 nm or less.

Accordingly, when the protective film is observed from the upper side, iridescence spots are not observed. Therefore, the protective film has an improved optical property, and thus can be optimally applied for a polarizing plate.

Particularly, when the protective film has the in-plane retardation and the thickness direction retardation as described above, it can have optimum optical properties necessary for a polarizing plate.

The protective film can be produced by the following process.

First, the polyester resins are respectively prepared. The polyester resins may be formed by the esterification reaction and the polymerization reaction of the diol component and the dicarboxylic acid as described above.

The polyester resins are respectively melted and extruded at the same time, and then cooled to produce a multi-layer unoriented sheet. Thereafter, the multi-layered non-stretched sheet is stretched in the longitudinal direction and the width direction, and is heat set to produce the protective film.

The melt extrusion is preferably carried out at a temperature of Tm + 30 to Tm + 60 占 폚. If the temperature of the extruder is lower than Tm + 30 占 폚 in the melt extrusion process, the melt will not be smoothly melted and the viscosity of the extrudate will increase to lower the productivity. Conversely, if the temperature exceeds Tm + 60 占 폚, the molecular weight of the resin decreases due to depolymerization due to thermal decomposition, A problem may arise. In addition, the cooling is preferably carried out at a temperature of 30 ° C or less, more preferably 15 to 30 ° C.

The unstretched sheet can be stretched by biaxial stretching.

The unstretched sheet can be stretched at a higher stretching ratio in the second direction than in the first direction. For example, the unstretched sheet may be stretched about 2 times to about 6 times in the first direction and about 2 times to about 6 times in the second direction. More specifically, the unstretched sheet may be stretched about 2.5 to about 4.5 times or about 2.5 to about 4 times in the first direction and about 2.5 to about 4.5 times or about 2.5 to about 4 times in the second direction Can be stretched.

The first direction and the second direction may be perpendicular to each other. The first direction may be a longitudinal direction (machine direction), and the second direction may be a width direction (tenter direction). Conversely, the first direction may be a width direction, and the second direction may be a length direction.

Further, the stretching speed in the longitudinal direction may be about 22 m / min to 500 m / min, preferably 25 m / min to 400 m / min. Further, the stretching speed in the width direction may be about 22 m / min to 500 m / min, preferably 25 m / min to 400 m / min.

At this time, if the elongation speed in the longitudinal direction is 22 m / min or more, the desired orientation property can be maintained in the present invention, and crystallinity is given according to the elongation speed in the longitudinal direction and the stretching ratio, It is different.

The stretching temperature is preferably in the range of Tg + 5 to Tg + 50 deg. C, and the lower the Tg, the better the stretchability, but the breakage may occur. In particular, in order to improve the brittleness, a stretching temperature range of Tg + 10 to Tg + 40 deg. C is preferable.

After initiating the heat setting, the film relaxes in the longitudinal direction and / or the width direction, and the heat setting temperature range is preferably 150 to 250 ° C.

Accordingly, a protective film having an appropriate thickness, in-plane retardation and thickness direction retardation can be produced. In addition, the protective film of the present invention can contain various additives such as ordinary electrostatic charge, antistatic, antiblocking agent and other inorganic lubricant within a range that does not impair the effect of the present embodiment.

By such a process, the protective film is produced, and the protective film can have improved optical and mechanical properties. In addition, since the protective film formed by the above process has low heat shrinkage, the polarizer layer can be efficiently protected.

Accordingly, the polarizing plate according to this embodiment can have improved optical characteristics, mechanical properties, and thermal properties.

Display device

The polarizing plate may be applied to a display device such as a liquid crystal display device or an organic light emitting display device.

A liquid crystal display (LCD)

3 is a cross-sectional view schematically showing a liquid crystal display device according to the present embodiment. Referring to FIG. 3, the liquid crystal display according to the present embodiment includes a liquid crystal panel and a backlight unit 20.

The backlight unit 20 emits light to the liquid crystal panel. The liquid crystal panel displays an image using light from the backlight unit 20. [ In more detail, the liquid crystal panel displays an image by adjusting the intensity of light emitted in units of pixels using light from the backlight unit 20. [

The liquid crystal panel includes an upper polarizer 11, a color filter substrate 13, a liquid crystal layer 14, a TFT substrate 15, and a lower polarizer plate 12.

The TFT substrate 15 and the color filter substrate 13 are opposed to each other. The TFT substrate 15 includes a plurality of pixel electrodes corresponding to each pixel, thin film transistors connected to the pixel electrodes, a plurality of gate lines for applying driving signals to the thin film transistors, And a plurality of data lines for applying a data signal to the pixel electrodes through transistors.

The color filter substrate 13 includes a plurality of color filters corresponding to respective pixels. The color filters may filter transmitted light to achieve red, green, and blue, respectively. In addition, the color filter substrate 13 may include a common electrode facing the pixel electrodes.

The liquid crystal layer 14 is interposed between the TFT substrate 15 and the color filter substrate 13. The liquid crystal layer 14 may be driven by the TFT substrate 15. More specifically, the liquid crystal layer 14 may be driven by an electric field formed between the pixel electrodes and the common electrode. The liquid crystal layer 14 can control the polarization direction of light passing through the lower polarizer 12. That is, the TFT substrate 15 can control a potential difference applied between the pixel electrodes and the common electrode in pixel units. Accordingly, the liquid crystal layer 14 can be driven to have different optical characteristics in pixel units.

At least one of the upper polarizer 11 and the lower polarizer 12 may have substantially the same configuration as the polarizer of the above-described manufacturing method.

The lower polarizer plate 12 is disposed below the TFT substrate 15. The lower polarizer plate 12 may be adhered to the lower surface of the TFT substrate 15.

The upper polarizer 11 is disposed on the color filter substrate 13. The upper polarizer 11 may be adhered to the upper surface of the color filter substrate 13.

The polarization directions of the upper polarizer 11 and the lower polarizer 12 may be the same or perpendicular to each other.

As described above, the upper polarizer 11 and / or the lower polarizer 12 include a protective film having an improved performance. Accordingly, the liquid crystal display device according to the present embodiment can have improved brightness, image quality, and durability.

Organic electroluminescence display < RTI ID = 0.0 >

4 is a cross-sectional view illustrating an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 4, the organic light emitting display according to the present embodiment includes a front polarizer 16 and an organic electroluminescent panel.

The front polarizer 16 may be disposed on the front surface of the organic electroluminescent panel. In more detail, the front polarizer 16 may be adhered to a surface of the organic electroluminescent panel on which an image is displayed. The front polarizer plate 16 may have substantially the same configuration as the polarizer plate in the above-described manufacturing method.

The organic electroluminescent panel displays an image by self-emission of a pixel unit. The organic electroluminescence panel includes an organic electroluminescence substrate 31 and a driving substrate 32.

The organic electroluminescent substrate 31 includes a plurality of organic electroluminescent units corresponding to pixels. Each of the organic electroluminescent units includes a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and a cathode.

The cathode and the anode are opposed to each other. The cathode and the anode are spaced apart from each other. At least one of the cathode and the anode is transparent. More specifically, at least one of the cathode and the anode may comprise a transparent conductive oxide.

The light emitting layer, the electron transporting layer, and the hole transporting layer are interposed between the cathode and the anode. The electron transporting layer is adjacent to the cathode, and the hole transporting layer is adjacent to the anode. The light emitting layer is interposed between the electron transporting layer and the hole transporting layer. That is, the organic electroluminescent units may be arranged in the order of the cathode, the electron transport layer, the light emitting layer, the hole transport layer, and the anode.

The anode may be transparent. Examples of the material used as the anode include indium tin oxide (ITO) and the like. In addition, the cathode may include a metal having a low work function such as aluminum. Light is emitted through the anode, and an image can be displayed.

The electron transporting layer transports electrons from the cathode to the light emitting layer. Examples of the material used for the electron transport layer include tris (8-hydroxyquinolinato) aluminum (Alq3).

The hole transporting layer transports holes from the anode to the light emitting layer. Examples of the material used as the hole transporting layer include N, N'-diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'- -diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine); NPB).

The light emitting layer couples electrons from the electron transport layer and holes from the hole transport layer to generate light. The light emitting layer may include a host and a dopant doped to the host. Examples of the material used as the host include carbazole-based or anthracene-based organic materials. Examples of the material used as the dopant include blue, green, and red fluorescent materials.

The driving substrate 32 is drivingly coupled to the organic electroluminescence substrate 31. That is, the driving substrate may be coupled to the organic light emitting substrate 31 so as to apply a driving signal such as a driving current. In more detail, the driving substrate 32 can drive the organic electroluminescent substrate 31 by applying currents to the organic electroluminescent units.

The driving substrate 32 may include a plurality of gate lines, a plurality of data lines, and a plurality of thin film transistors.

Since the front polarizer 16 has improved optical characteristics, mechanical characteristics, and thermal characteristics, the organic light emitting display device according to the present embodiment can have improved brightness, image quality, and durability.

Hereinafter, the present invention will be described in more detail by way of examples. The following examples are illustrative of the present invention, but the present invention is not limited to the following examples.

Examples 1 to 4

(Polyethylene terephthalate glycol (PETG, 100 mol% terephthalic acid, 70 mol% ethylene glycol, cyclohexamethyl (ethylene terephthalate)), polyethylene terephthalate (PET, 100 mol% terephthalic acid, 100 mol% ethylene glycol, IV 0.61 dl / (Containing 30 mol% of alcohol, specific gravity: 1.27) and / or polystyrene glycol terephthalate (SPG1 (containing 20 mol% of spiroglycol and IV 0.67 dl / g) or SPG2 (containing 30 mol% of spiroglycol and 0.67 dl / g ), Product name: ALTESTER, manufactured by Mitubishi Gas Chemical Co., Ltd.) was selected as shown in Table 1 below, melt-extruded through an extruder at about 275 ° C and then cooled in a casting roll at about 25 ° C to obtain a multi- . The thus obtained multilayered unstretched sheet was directly heated to 85 ° C and then heated in a R / H (radiation heater) to be stretched in the longitudinal direction stretching ratio shown in Table 1 below, preheated at 100 ° C, . Thereafter, the stretched sheet was heat set at about 180 캜 for about 30 seconds to prepare a multilayer film.

Comparative Examples 1 and 2

The PET or SPG1 used in Examples 1 to 4 was melt-extruded through an extruder at about 280 DEG C and then cooled in a casting roll at about 25 DEG C to prepare an unoriented sheet. The unstretched sheet was immediately heated to 80 ° C, heated with a R / H (radiation heater), stretched at the longitudinal stretching ratio shown in Table 1 below, preheated at 110 ° C, stretched at 140 ° C in the transverse direction Respectively. Thereafter, the stretched sheet was heat set at about 225 캜 for about 30 seconds to prepare a single-layer film.

division thickness
(탆) Floor composition Refractive index Layer thickness ratio Stretching cost
(MD / TD) Heat setting temperature ( ^o C) Example 1 25 SPG1 / PET / SPG1 1.52 / 1.64 / 1.52 1: 1: 1 2.8 / 3.1 150 Example 2 25 SPG1 / PET / SPG1 1.52 / 1.64 / 1.52 1: 1: 1 2.8 / 3.1 180 Example 3 25 PET / SPG2 / PET 1.64 / 1.51 / 1.64 1: 3: 1 2.8 / 3.1 180 Example 4 25 PET / PETG / PET 1.64 / 1.53 / 1.64 1: 2.5: 1 2.8 / 3.2 180 Comparative Example 1 25 PET 1.648 fault 2.8 / 3.2 225 Comparative Example 2 25 SPG1 1.502 fault 2.8 / 3.1 150

The thus prepared protective films were evaluated as follows, and the results are shown in Table 2 below.

(1) In-plane retardation (Ro)

The in-plane retardation is a parameter defined by a product (DELTA Nxy x d) of the anisotropy (DELTA Nxy = | Nx-Ny |) of the refractive index of the orthogonal biaxial film on the film and the film thickness d (nm), and represents optical anisotropy and anisotropy It is a scale. The anisotropy (? Nxy) of the refractive index of the biaxial axis was obtained by the following method. Using two polarizing plates, the orientation axis direction of the film was determined, and a rectangle of 4 cm x 2 cm was cut out so that the orientation axis direction was orthogonal to each other. The refractive index (Nx, Ny) and the refractive index (Nz) in the direction perpendicular to the biaxial axis were measured by Abbe's refractive index meter (NAR-4T manufactured by Atago Corporation, measurement wavelength: 589 nm) (? Nx-Ny |) is defined as anisotropy (? Nxy) of the refractive index. The thickness d (nm) of the film was measured using an electric micrometer (Millitron 1245D, manufactured by Pahrung Paste), and the unit was converted to nm. The in-plane retardation Ro was obtained from the product (Nxy x d) of the anisotropy of the refractive index (DELTA Nxy) and the thickness of the film d (nm).

(2) Thickness direction retardation (Rth)

The thickness direction phase difference refers to an average of phase differences obtained by multiplying the birefringence ΔNxz (= | Nx-Nz |) and ΔNyz (= | Ny-Nz | Parameter. Nx, Ny and Nz and the film thickness d (nm) were determined in the same manner as in the measurement of the in-plane retardation (1), and the average value of (DELTA Nxz x d) and (DELTA Nyz x d) ) Were obtained.

(3) Rainbow stain observation

A polyester film produced by a method described later on one side of a polarizer made of PVA and iodine was stuck to the polarizer so that the absorption axis of the polarizer and the main axis of alignment of the film were perpendicular to each other, and a TAC film (manufactured by Fuji Film Co., Thickness: 80 mu m) was attached thereto to prepare a polarizing plate. The polarizing plate thus obtained was placed so that the polyester film became visible on the outgoing light side of a liquid crystal display device using a white LED as a light emitting element in combination with a blue light emitting diode and a yttrium aluminum garnet yellow phosphor as a light source (Nichia Corporation, NSPW500CS) Respectively. This liquid crystal display device has a polarizing plate that uses two TAC films as a polarizer protective film on the incident light side of the liquid crystal cell. The front side and the oblique direction of the polarizing plate of the liquid crystal display were observed with naked eyes to determine whether rainbow colored unevenness occurred or not.

◎: Rainbow color unevenness does not occur in any direction.

○: When observed in the oblique direction, a color tone was observed on a part in a light color.

X: Irregular irregularity is clearly observed when observed from the front and oblique directions.

(4) Heat shrinkage

The resulting film was cut into a size of 10 cm x 10 cm, and then heat-treated in an oven at about 80 DEG C for about 4 hours, cooled at room temperature, and then measured for shrinkage.

division Heat shrinkage
(MD / TD) Plane retardation (nm) Thickness direction
The phase difference (nm) Rth / Ro Exterior
(Rainbow stain) Example 1 0.8 / 1.0 117 2049 17.5 ○ Example 2 0.5 / 0.5 123 2301 18.7 ○ Example 3 0.7 / 0.8 96 1163 12.1 ◎ Example 4 0.6 / 0.7 112 2038 18.2 ○ Comparative Example 1 0.3 / 0.1 74 4460 56.5 X Comparative Example 2 2.1 / 2.3 191 612 3.2 ○

From the results of the tests in Table 2, it can be seen that Examples 1 to 4 have a significantly lower retardation in the thickness direction than Comparative Example 1, have excellent appearance (rainbow stain) observation results, It is clear that it has excellent and certainly low in-plane retardation.

320: protective film 321: first polyester layer
322: second polyester layer 323: third polyester layer
11: upper polarizer 310: protective film
220: Polarizer layer 12: Lower polarizer plate
13: color filter substrate 14: liquid crystal layer
15: TFT substrate 20: backlight unit
16: front polarizer 31: organic electroluminescence substrate
32: driving substrate

Claims (12)

A first polyester layer comprising a first polyester resin; And
A second polyester layer disposed on the first polyester layer and comprising a second polyester resin,
Wherein when the refractive index of the first polyester resin is 1.60 or more, the refractive index of the second polyester resin is 1.56 or less,
When the refractive index of the first polyester resin is 1.56 or less, the refractive index of the second polyester resin is 1.60 or more,
Plane retardation of 300 nm or less,
The retardation in the thickness direction is 2400 nm or less,
Wherein the heat shrinkage ratio is 3% or less based on the longitudinal direction and the width direction when the film is heat-treated at a temperature of 80 占 폚 for 4 hours.
The method according to claim 1,
Wherein the in-plane retardation is 200 nm or less and the retardation in the thickness direction is 2000 nm or less.
3. The method of claim 2,
Wherein the in-plane retardation is 100 nm or less and the thickness direction retardation is 1200 nm or less.
The method according to claim 1,
Wherein the protective film for polarizing plate has a thickness of 10 占 퐉 to 60 占 퐉.
5. The method of claim 4,
Wherein the polarizing plate protective film is stretched 2.5 to 4.5 times in the longitudinal direction and 2.5 to 4.5 times in the width direction.
The method according to claim 1,
Wherein the first polyester resin is polyethylene terephthalate and the second polyester resin comprises (i) a diol component comprising spiroglycol in an amount of 5 to 50 mole percent, based on the total amount of the diol component, and (ii) a dicarboxylic acid A protective film for a polarizing plate.
The method according to claim 1,
Wherein the protective film for polarizing plate further comprises a third polyester layer disposed under the first polyester layer,
Wherein the third polyester layer comprises a third polyester resin,
Wherein the first polyester resin comprises: (i) a diol component comprising 5 to 50 mole percent spiroglycol, and (ii) a dicarboxylic acid component, based on the total amount of the diol component,
Wherein the second polyester resin and the third polyester resin comprise polyethylene terephthalate,
Wherein the ratio of the sum of the thicknesses of the second polyester layer and the third polyester layer to the thickness of the first polyester layer is 1: 5 to 5: 1.
8. The method of claim 7,
Wherein the refractive index of the first polyester resin is 1.56 or less and the refractive index of the second and third polyester resins is 1.60 or more.
The method according to claim 1,
Wherein the protective film for polarizing plate further comprises a third polyester layer disposed under the first polyester layer,
Wherein the third polyester layer comprises a third polyester resin,
Wherein the second polyester resin and the third polyester resin comprise (i) a diol component comprising 5 to 50 mole percent spiroglycol, and (ii) a dicarboxylic acid component, based on the total amount of the diol component,
Wherein the first polyester resin comprises polyethylene terephthalate,
Wherein the ratio of the sum of the thicknesses of the second polyester layer and the third polyester layer to the thickness of the first polyester layer is 1: 5 to 5: 1.
10. The method of claim 9,
Wherein a refractive index of the first polyester resin is 1.60 or more and a refractive index of the second and third polyester resins is 1.56 or less.
A polarizer layer; And
And a protective film according to claim 1 adjacent to at least one of the upper surface and the lower surface of the polarizer layer.
Display panel; And
And a polarizing plate according to claim 11 disposed on at least one of an upper surface and a lower surface of the display panel.

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