TW202100632A - Polyester film and organic light emitting display device using the same having excellent optical properties, durability, heat resistance and color expression - Google Patents

Abstract

An embodiment of the present invention relates to a polyester film and an organic light emitting display device using the same. The polyester film includes: a substrate layer including a polyester resin; and a coating layer provided on the substrate layer and including a dichroic dye. In the wavelength range of 380 nm to 780 nm, the polyester film has a degree of polarization exceeding 50% and a light transmittance of more than 40%, and it has excellent optical properties, durability, heat resistance and color expression.

Description

Polyester film and organic light emitting display device using the same

The embodiment relates to a polyester film excellent in optical properties, durability, heat resistance, and color expression, and an organic light-emitting display device using the polyester film.

Flat Panel Display (Flat Panel Display) is used in various electronic products such as mobile phones, tablet computers, notebook computers, etc. Liquid Crystal Display (Liquid Crystal Display) and Organic Light Emitting Display (Organic Light Emitting Display) are widely used in this flat panel display In the installation.

The liquid crystal display device requires a polarizing film with a high degree of polarization in order to effectively transmit backlight light. On the other hand, since the organic light-emitting display device uses an organic light-emitting element which is a self-luminous element that emits light when a voltage is applied, a polarizing film is used in order to accurately achieve a black screen and ensure outdoor visibility.

At present, although the required characteristics of liquid crystal display devices and organic light emitting display devices are different, polarizing films used in liquid crystal display devices are still used in organic light emitting display devices. However, for organic light emitting display devices, since high polarization optical properties are not required, it is necessary to develop a polarizing film having optical properties suitable for organic light emitting display devices and ensuring color realization and outdoor visibility.

For example, in Japanese Laid-open Patent No. 2005-266502, although the polarization degree of the polarizing film is 95% or more, the transmittance is at least 40% or more. Therefore, even if the high degree of polarization required for liquid crystal display devices is satisfied, the light loss is large. , So the color performance is low, so it is not suitable for organic light-emitting display devices.

This application claims the priority of Chinese patent application 10-2019-0077867 whose filing date is 2019/6/28. This application quotes the full text of the aforementioned Chinese patent application.

Therefore, the embodiment provides a polyester film that has optical properties suitable for an organic light-emitting display device and is excellent in durability, heat resistance, and color expression, and an organic light-emitting display device using the polyester film.

The polyester film according to one embodiment includes: a substrate layer including a polyester resin; and a coating layer, which is provided on the substrate layer and includes a dichroic dye, and the polyester film is 380 In the wavelength range from nm to 780 nm, the degree of polarization is more than 50%, and the light transmittance is more than 40%.

A polarizing plate for an organic light emitting element according to an embodiment includes the polyester film as in the above embodiment.

An organic light emitting display device according to an embodiment includes a polarizing plate for an organic light emitting element as in the above embodiment.

A method of manufacturing a polyester film according to an embodiment includes: (1) a step of melt-extruding a polyester resin to produce an unstretched sheet; (2) a step of initially extending the unstretched sheet in a first direction (3) the step of coating a composition containing a dichroic dye on the previously stretched sheet; and (4) the second stretch of the coated sheet along a second direction perpendicular to the first direction Material steps.

The polyester film according to an embodiment has optical properties suitable for an organic light-emitting display device, and has excellent durability, heat resistance, and color expression.

Preferred embodiment

Hereinafter, the present invention will be explained in detail through embodiments. The embodiment is not limited to the content disclosed below, and can be changed in various forms without changing the gist of the present invention.

In this specification, when each layer, film or sheet is described as being provided on or under each layer, film or sheet, it includes directly or indirectly via Other component settings.

In this specification, when a component "includes" a certain component, unless otherwise specified, the component may further include other components without excluding other components.

It should be understood that, unless otherwise specified, in all cases, the term "about" is used to modify all numbers and expressions representing the amounts of ingredients, reaction conditions, etc. described in this specification.

Polyester film

The polyester film according to one embodiment includes: a substrate layer including a polyester resin; and a coating layer, which is provided on the substrate layer and includes a dichroic dye, and the poly The ester film has a polarization degree of more than 50% in the wavelength range of 380 nm to 780 nm, and a light transmittance of more than 40%.

According to one embodiment, the above-mentioned base material layer is a polyester resin layer.

According to one embodiment, the polyester resin of the substrate layer includes a diol component and a dicarboxylic acid component. Specifically, the above-mentioned base material layer may be formed through a polyester resin including a diol component and a dicarboxylic acid component.

According to an embodiment, the above-mentioned diol component may be composed of a linear or branched aliphatic C2-C10 diol. That is, the aforementioned diol component may not include alicyclic diol or aromatic diol. When a polyester resin containing a diol component composed of a linear or branched aliphatic C2-C10 diol is used to manufacture a film or sheet through melt extrusion, the film has excellent chemical resistance due to good filling performance And surface strength.

Specifically, the above-mentioned linear or branched aliphatic C2-C10 diol may include ethylene glycol, diethylene glycol, neopentyl glycol, 1,3-propanediol, 1,2-octanediol, 1,3- Octanediol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-butyl-2-ethyl-1,3- Propylene glycol, 2,2-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1 -Dimethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-3-methyl-1,5-hexanediol, 2-ethyl-3-ethyl-1 ,5-hexanediol, 1,7-heptanediol, 2-ethyl-3methyl-1,5-heptanediol, 2-ethyl-3-ethyl-1,6-heptanediol, Derivatives such as 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, or any combination thereof, but are not limited thereto.

According to an embodiment, the above-mentioned glycol component may include selected from ethylene glycol, diethylene glycol, cyclohexanedimethanol (CHDM), propylene glycol, butylene glycol, pentanediol, hexanediol, and octanediol. At least one, the diol component in this case may be substituted or unsubstituted with C1 to C6 alkyl.

According to one embodiment, the aforementioned glycol component may include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propanediol, 1,2-octanediol, 1,3-octanediol , 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 2-butyl-2-ethyl-1, 3-propanediol, 2,2-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1 ,1-Dimethyl-1,5-pentanediol or a combination thereof.

According to an embodiment, the aforementioned glycol component may include at least one selected from ethylene glycol, diethylene glycol, neopentyl glycol, and cyclohexanedimethanol.

According to an embodiment, the polyester resin may include 30 mol% to 90 mol% of ethylene glycol based on the total moles of the diol components. For example, based on the total moles of the above-mentioned glycol components, the polyester resin may include 40 mole% to 90 mole%, 50 mole% to 85 mole%, or 65 mole% to 85 mole%.的ethylene glycol.

According to an embodiment, the polyester resin may include 30 to 90 mol% neopentyl glycol based on the total mol of the diol component. For example, based on the total moles of the above-mentioned glycol components, the polyester resin may include 35 mole% to 90 mole%, 35 mole% to 80 mole%, and 35 mole% to 75 mole%. , 35 mol% to 70 mol%, 40 mol% to 65 mol%, 40 mol% to 60 mol% neopentyl glycol. When the above range is satisfied, the crystal properties may be easily controlled.

The aforementioned dicarboxylic acid component may be an aromatic dicarboxylic acid, for example, terephthalic acid, dimethylterephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, phthalic acid, etc.; aliphatic dicarboxylic acid, for example , Adipic acid, azelaic acid, sebacic acid, decane dicarboxylic acid, etc.; cycloaliphatic dicarboxylic acid; its esterified product; or a combination thereof. Specifically, the aforementioned dicarboxylic acid component may be composed of terephthalic acid, dimethyl terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, phthalic acid, or a combination thereof.

According to one embodiment, the aforementioned dicarboxylic acid component may include an aromatic dicarboxylic acid. For example, based on the total moles of the dicarboxylic acid component, the dicarboxylic acid component may include terephthalic acid in an amount of 80 mol% or more, 90 mol% or more, or 95 mol% or more.

According to an embodiment, the intrinsic viscosity (IV) of the polyester resin may be 0.60 dl/g to 3.0 dl/g. For example, the intrinsic viscosity of the polyester resin may be 0.63 dl/g to 1.2 dl/g, 0.65 dl/g to 1.1 dl/g, or 0.67 dl/g to 1.0 dl/g. When the above range is satisfied, the calenderability is excellent, the kinematic viscosity retention in the rolling process is excellent, and the thickness uniformity of the sheet and film is excellent.

According to one embodiment, the heat of crystallization of the polyester resin may be 2.5 J/g or less. For example, the heat of crystallization of the above polyester resin may be 0 to 2.2 J/g or 0 to 2 J/g. When the above range is satisfied, there is an effect of improving the calenderability.

According to one embodiment, based on the total weight of the coating, the coating may include 0.5 wt% or more to less than 50 wt% of the dichroic dye. For example, based on the total weight of the coating, the coating may include 0.5 wt% or more to less than 20 wt%, 4 wt% to 18 wt%, or 4 wt% to 16 wt% of dichroic dye. Specifically, based on the total weight of the above-mentioned coating, the above-mentioned coating may include 4% by weight or more to less than 20% by weight of the dichroic dye. When the above range is satisfied, optical properties suitable for light transmittance, haze, and polarization of an organic light emitting display device can be obtained, and deterioration of the dispersibility of the coating layer due to excessive content of the dichroic dye can be prevented.

According to an embodiment, the dichroic ratio of the dichroic dye may be 1.5-14. For example, the dichroic ratio of the above-mentioned dichroic dye may be 2-14, 3-14, or 4-14.

According to an embodiment, the above-mentioned dichroic dye may have an absorbance of 0.4 or less in a wavelength range of 380 nm to 780 nm. For example, the aforementioned dichroic dye may have an absorbance of 0.39 or less or 0.38 or less in a wavelength range of 380 nm to 780 nm.

According to an embodiment, the melting point (Tm) of the dichroic dye may be 100°C to 140°C. For example, the melting point (Tm) of the aforementioned dichroic dye may be 100°C to 130°C or 110°C to 140°C.

According to one embodiment, the dichroic dye may be an azo compound, an anthraquinone compound, an azomethine compound, an indigo compound, a thioindigo compound, a cyanine compound, an indane compound , Azulene (azulene) compounds, perylene (Perylene) compounds, phthaloperinone (phthaloperinone) compounds or azin (azin) compounds.

According to an embodiment, the above-mentioned coating may further include a primer.

According to an embodiment, the aforementioned primer may include at least one selected from the group consisting of a binder resin, a curing agent, a dispersant, and a surfactant.

According to an embodiment, the aforementioned binder resin may include at least one selected from acrylic resin, polyurethane resin, and polyester resin.

The above acrylic resin may be polydipentaerythritol pentaacrylate, trihydroxyethyl isocyanurate triacrylate, di(meth)acrylic acid oxyethyl isocyanurate, isocyanurate di(methyl) ) Acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, ethylene oxide modified hexahydrophthalic di(meth)acrylate, dipentaerythritol tri( Meth) acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, propylene oxide modified Trimethylolpropane tri(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, tris(propylene oxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta(methyl) ) Acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, or a combination thereof, but not limited thereto.

The aforementioned polyurethane resin may include polyester polyurethane resin, but is not limited thereto. For example, the above-mentioned polyurethane resin may be a water-dispersible polyurethane resin, and as a commercially available product, it may be HYDRAN AP-20 of DIC Corporation, etc., but it is not limited thereto.

The above-mentioned polyester resin may be polyethylene terephthalate or copolymerized polyethylene terephthalate, but is not limited thereto.

According to an embodiment, the thickness of the coating layer may be 100 nm or less. For example, the thickness of the coating may be 10 nm to 100 nm, 20 nm to 100 nm, 30 nm to 100 nm, 30 nm to 80 nm, 30 nm to 70 nm, or 30 nm to 60 nm.

According to an embodiment, based on the total weight of the coating, the coating may include a binder resin in an amount of 5% to 30% by weight. For example, based on the total weight of the coating, the coating may include 5 wt% to 25 wt%, 8 wt% to 20 wt%, or 10 wt% to 15 wt% of binder resin.

If necessary, the aforementioned primer may include curing agents, surfactants, and dispersants commonly used in the art to promote the reaction or improve coating performance.

Although the curing agent commonly used in this field is not specifically limited, if it is exemplified, oxaline, epoxy, carbimidate, melamine, etc. curing agents can be used.

Although the dispersant commonly used in this field is not specifically limited, if an example is given, alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, isopropyl tristearyl titanate, isopropyl tris( Dodecylbenzenesulfonyl) titanate, tetraoxytitanium oxide and other titanium compounds, silane compounds, polycarboxylic acids, polycarboxylic acid esters and other carboxylic acid compounds, polyvinylpyrrolidone, N-vinylpyrrolidone, etc. Vinylpyrrolidone compounds.

Although it is not specifically limited to the above-mentioned surfactants used to improve the dispersibility of particles, as an example, a surface active having at least one functional group selected from an alkoxy group, a hydroxyl group, an amino group, and a conjugated double bond can be used. Agent.

According to an embodiment, the weight ratio of the primer and the dichroic dye may be 2 to 20:1. For example, the weight ratio of the primer and the dichroic dye may be 2.5 to 20:1, 2.5 to 15:1, 3 to 13:1, 3 to 10:1, 3 to 8:1, or 3 to 5. :1. When the above range is satisfied, optical characteristics suitable for light transmittance, haze, and polarization of an organic light emitting display device can be obtained.

According to an embodiment, in the wavelength range of 380 nm to 780 nm, the degree of polarization of the polyester film exceeds 50%. For example, in the wavelength range of 380 nm to 780 nm, the polarization degree of the polyester film can be 50% or more, 53% or more, 55% or more, 50% to 90%, 50% to 85%, 50% to 80 %, 53% to 80%, 54% to 80%, 54% to 75%, 54% to 70%, 54% to 65%, or 54% to 60%.

According to one embodiment, the light transmittance of the polyester film is 40% or more. Specifically, in the wavelength range of 380 nm to 780 nm, the light transmittance of the polyester film is 40% or more. For example, the light transmittance of the above polyester film may be 50% or more, 55% or more, 60% or more, 65% or more, 40% to 90%, 50% to 80%, 55% to 75%, 60% to 75%. %, or 65% to 75%.

According to one embodiment, the haze of the polyester film is 10% or less. For example, the haze of the polyester film may be 9% or less, 8.5% or less, 3% to 9%, 4% to 9%, 5% to 8.5%, or 5.5% to 8.5%.

According to an embodiment, the thickness of the above-mentioned polyester film may be 10 μm to 200 μm. For example, the thickness of the above polyester film is 10 μm to 188 μm, 10 μm to 125 μm, 20 μm to 188 μm, 23 μm to 125 μm, 30 μm to 188 μm, 38 μm to 125 μm, or 38 μm to 100 μm.

The above-mentioned polyester film can be used as a polarizing film.

A polarizing plate for an organic light emitting element according to an embodiment includes the polyester film as in the above embodiment.

An organic light emitting display device according to an embodiment includes a polarizing plate for an organic light emitting element as in the above embodiment.

Manufacturing method of polyester film

A method of manufacturing a polyester film according to an embodiment includes: (1) a step of melt-extruding a polyester resin to produce an unstretched sheet; (2) a step of initially extending the unstretched sheet in a first direction (3) the step of coating a composition containing a dichroic dye on the previously stretched sheet; and (4) the second stretch of the coated sheet along a second direction perpendicular to the first direction Material steps.

step 1)

The above step (1) is a step of manufacturing an unstretched sheet by melt-extrusion of the polyester resin.

According to one embodiment, the above-mentioned polyester resin can be produced by polymerizing a diol component and a dicarboxylic acid component using at least one catalyst selected from a germanium-based compound, an antimony-based compound, an aluminum-based compound, and a titanium-based compound.

The description of the aforementioned diol component and dicarboxylic acid component is as described above.

According to one embodiment, melt extrusion can be performed at a temperature of 250°C or higher.

For example, it can be performed at a temperature of 255°C or higher, 260°C or higher, 270°C or higher, 280°C or higher, 200°C to 300°C, 230°C to 280°C, or 250°C to 280°C. The beneficial effect of the above-mentioned polyester film is that even in the above-mentioned temperature range, the heat resistance is strong, and therefore, no defect occurs. Specifically, since thermal decomposition may occur at the temperature of the melt extrusion process, it is not suitable to use non-dichroic dyes without substantial dichroic ratio. For example, the aforementioned non-dichroic dye may have a dichroic ratio of less than 1, but it is not limited to this.

Step (2)

Step (2) is a step of extending the unstretched sheet for the first time along the first direction.

According to an embodiment, the aforementioned sheet may be preheated at a constant temperature before stretching. Based on the glass transition temperature (Tg) of the above resin, the above preheating temperature may be Tg+5°C to Tg+50°C. For example, the aforementioned preheating temperature may be 70°C to 90°C. When the above range is satisfied, the flexibility of the easily stretched sheet can be ensured, and cracking during stretching can be effectively prevented.

In this specification, the above-mentioned first direction may be the longitudinal direction (MD) or the transverse direction (TD). For example, the first direction may be the longitudinal direction (MD), and the second direction perpendicular to the above-mentioned first direction may be the transverse direction (TD). Alternatively, the first direction may be a transverse direction (TD), and the second direction perpendicular to the first direction may be a longitudinal direction (MD).

According to an embodiment, the aforementioned primary stretch ratio may be 1.0 to 4.0. For example, it can be 1.0 to 3.5, 1.3 to 3.5, 1.5 to 3.3, or 1.5 to 3.0.

According to an embodiment, the temperature during the extension in the first direction may be 55°C to 120°C. For example, the stretching in the above-mentioned first direction may be performed at 70°C to 120°C or 80°C to 110°C.

Step (3)

Step (3) is a step of coating a composition containing a dichroic dye on the sheet after the initial stretching.

The description of the above dichroic dye is as described above.

According to an embodiment, the aforementioned coating may be spin coating or in-line coating. Specifically, it is preferable to coat on the wire to ensure heat resistance, but it is not limited to this.

Step (4)

Step (4) is a step of extending the coated sheet twice along a second direction perpendicular to the first direction.

According to an embodiment, the aforementioned sheet may be preheated at a constant temperature before stretching. Based on the glass transition temperature (Tg) of the above resin, the above preheating temperature may be Tg+5°C to Tg+50°C. For example, the aforementioned preheating temperature may be 70°C to 90°C. When the above range is satisfied, the flexibility of the easily stretched sheet can be ensured, and cracking during stretching can be effectively prevented. In this specification, the above-mentioned second direction may be the longitudinal direction (MD) or the transverse direction (TD).

According to an embodiment, the extension ratio in the second direction may be 2.0 to 5.0. For example, it can be 2.0 to 4.8, 2.5 to 4.5, 2.5 to 4.3, or 3.0 to 4.0.

According to an embodiment, the temperature when extending along the second direction may be 55°C to 120°C. For example, the extension along the above-mentioned second direction may be performed at 90°C to 120°C or 100°C to 120°C.

According to an embodiment, the ratio of the stretch ratio of the primary stretch to the stretch ratio of the secondary stretch (ie, the ratio of the primary stretch ratio to the secondary stretch ratio) may be 1:1 to 5. For example, the ratio of the extension ratio of the aforementioned primary extension to the extension ratio of the aforementioned secondary extension may be 1:1 to 4, 1:1 to 3, or 1:1 to 2.

According to one embodiment, in steps (1) to (4), the maximum process temperature may be 250° C. or more. For example, in steps (1) to (4), the maximum process temperature can be above 255 ℃, 260 ℃ above, 270 ℃ above, 280 ℃ above, 200 ℃ to 300 ℃, 230 ℃ to 280 ℃, or 250 ℃ to 280 ℃. The beneficial effect of the above-mentioned polyester film is that even in the above-mentioned temperature range, the heat resistance is strong, and therefore, no defect occurs.

Detailed ways

The above content is described in more detail through the following examples. However, the following examples are only used to illustrate the present invention, and the scope of the examples is not limited thereto.

Example 1

In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux cooler, terephthalic acid (TPA) as the dicarboxylic acid component and ethylenedioxide as the diol component were mixed at a molar ratio of 1.7:1.0 Alcohol (EG) is then distilled to remove the generated methanol while carrying out the transesterification reaction. After that, a polycondensation reaction was carried out at 280°C and a reduced pressure of 26.6 Pa (0.2 Torr) to obtain a polyester resin.

The above resin was melt-extruded in an extruder at 280 ℃ and guided to a t-die (T-Die) to form an unstretched sheet, and then the above-mentioned sheet was stretched along the MD direction at 1.0 to 1.5 using a stretching device Stretch ratio for the first stretch.

Manufacture containing 10 grams of binder resin (Polyester-based Goo Chemical Company’s Z690), dichroic dye (Sigma-Aldrich’s Chlorazol black (Chlorazol black)) 5 grams, and curing agent (Nippon Catalysts Company’s WS500) 10 grams G, other additives and an appropriate amount of distilled water, then use the above composition to coat the above sheet.

Then, the above-mentioned coated sheet was stretched along the TD direction at a stretch ratio of 3.0 to 4.8 to produce a polyester film with a thickness of 50 μm.

Examples 2 to 6 and Comparative Examples 1 to 3

Repeat the steps of Example 1 above, but change the composition and content of the coating as shown in Table 1 below to prepare a polyester film.

On the other hand, in Comparative Example 1, a composition in which only the dye was mixed with water without using a binder was used as the coating liquid. In this case, the adhesion between the coating liquid and the polyester resin layer was low, so No coating was formed on the polyester resin layer.

In addition, in Comparative Examples 2 and 3, ordinary dyes (FASTOGEN, DIC Corporation) were used, but dichroic dyes were not used.

【Table 1】 ingredient Primer content (g) Dye content (g) Primer: Dye weight ratio Dye content in the coating (wt%) Comparative example 1 - - - - Example 1 10 5.0 twenty one 12.00 Example 2 10 2.5 4: 1 6.00 Example 3 10 2.0 5: 1 3.33 Example 4 10 1.5 6.7: 1 2.61 Example 5 10 1.0 10: 1 1.82 Example 6 10 0.5 20: 1 0.95 Comparative example 2 10 3.0 3.3: 1 4.62 Comparative example 3 10 2.5 4: 1 4.00

Evaluation example 1: Light transmittance

A UV-spectrometer (Shimadzu Corporation, UV-2450, Japan) was used to measure the light transmittance.

Evaluation example 2: Haze

A haze meter NDH-5000W manufactured by Nippon Denshoku Industries Co., Ltd. was used to measure the haze.

Evaluation example 3: Polarization

A UV-spectrometer (Shimadzu, Japan, UV-2450) was used to measure the degree of polarization.

Evaluation example 4: Moisture resistance

Cut into a size of 10 cm×10 cm to prepare two polyester films. After overlapping so that one surface of the two polyester films is in contact with each other, they are compressed under a load of 10 kg at 80°C/80% RH for 24 hours. After cooling the compressed polyester film to normal temperature, the transmittance change of the film was measured. When the transmittance change was 1% or more, it was marked as X, and when it was less than 1, it was marked as O.

The results of the above evaluation examples 1 to 4 are shown in Table 2 below.

【Table 2】 ingredient Transmittance(%) Haze (%) Polarization (%) Moisture resistance Comparative example 1 53.31 31.21 53 X Example 1 50.66 1.11 80 O Example 2 50.35 1.84 60 O Example 3 51.47 2.76 58 O Example 4 51.53 2.57 57 O Example 5 53.52 2.35 56 O Example 6 59.36 2.22 51 O Comparative example 2 52.52 21.11 0.5 X Comparative example 3 51.37 19.43 0.2 X

As shown in Table 2 above, compared with the polyester film produced in the comparative example, the polyester film produced in the example has balanced and excellent optical properties such as light transmittance, polarization and haze, and moisture resistance, so it can It is seen that it is suitable for use in organic light-emitting display devices. Specifically, it can be seen that the polyester film of the example using the dichroic dye has balanced and excellent optical properties of light transmittance, polarization and haze, and moisture resistance, while the comparative example 1 and the comparative example 1 without using the dye Comparative Examples 2 and 3 using common dyes have poor haze, polarization and moisture resistance.

no

no

Claims (10)

A polyester film, including: A substrate layer, which contains polyester resin; and, The coating is provided on the substrate layer and contains a dichroic dye, In the wavelength range of 380 nm to 780 nm, the polyester film has a polarization degree of more than 50% and a light transmittance of more than 40%. The polyester film according to claim 1, wherein the haze of the polyester film is 10% or less, and the thickness of the polyester film is 10 μm to 200 μm. The polyester film according to claim 1, wherein the polyester resin of the substrate layer includes a diol component and a dicarboxylic acid component; The dichroic dyes are azo compounds, anthraquinone compounds, azomethine compounds, indigo compounds, thioindigo compounds, cyanine compounds, indan compounds, chamomile compounds, perylene compounds , Phthapyrinone compounds or azine compounds. The polyester film according to claim 1, wherein, based on the total weight of the coating, the coating includes 4% by weight or more and less than 20% by weight of the dichroic dye. The polyester film according to claim 1, wherein the dichroic ratio of the dichroic dye is 1.5 to 14. The polyester film according to claim 1, wherein the dichroic ratio of the dichroic dye is 1.5 to 14. The polyester film according to claim 1, wherein the coating further includes a primer; The primer includes at least one selected from a binder resin, a curing agent, a dispersant, and a surfactant. The polyester film according to claim 7, wherein the binder resin comprises at least one selected from acrylic resin, polyurethane resin and polyester resin; Based on the total weight of the coating, the coating includes 5 wt% to 30 wt% of the binder resin; The weight ratio of the primer and the dichroic dye is 2 to 20:1. A manufacturing method of polyester film, including: (1) The step of manufacturing an unstretched sheet through melt extrusion of the polyester resin; (2) A step of initially extending the unstretched sheet along the first direction; (3) The step of coating a composition containing a dichroic dye on the sheet after the initial stretching; and, (4) A step of extending the coated sheet twice along a second direction perpendicular to the first direction. The method for producing a polyester film according to claim 9, wherein the polyester resin uses at least one catalyst selected from germanium-based compounds, antimony-based compounds, aluminum-based compounds, and titanium-based compounds to reduce the diol component Manufactured by polymerization with dicarboxylic acid components; The ratio of the extension ratio of the primary extension to the extension ratio of the secondary extension is 1:1 to 5; In steps (1) to (4), the maximum process temperature is 250 ℃ or more.