KR102356860B1 - Polyimide film, cover window and display device comprsing the same - Google Patents

Abstract

The present invention relates to a polyimide film, a cover window and a display including the same, wherein the polyimide film according to the present invention includes repeating units represented by [Formula 1] and [Formula 2], and has a UV transmittance of 10% is below.

Description

POLYIMIDE FILM, COVER WINDOW AND DISPLAY DEVICE COMPRSING THE SAME

The present invention relates to a polyimide film, a cover window and a display device including the same, and more particularly, a polyimide film developed to prevent deterioration of polarization characteristics when a polarizing layer is integrally formed due to low ultraviolet transmittance. , to a cover window and a display device including the same.

A cover window for protecting a panel is applied to a surface of a display device such as a liquid crystal display (LCD) or an organic light emitting display (OLED). Conventionally, as a material of the cover window, tempered glass having excellent flatness, heat resistance, chemical resistance and barrier performance against moisture or gas, a small coefficient of linear expansion, and high light transmittance has been mainly used.

Meanwhile, flexible displays such as curved displays or foldable displays have recently been developed. In order to be applied to such a flexible display, the cover window must also have flexibility, but in the case of a conventional glass cover window, it is not suitable for a flexible display because it is heavy and easy to break and has poor flexibility.

Due to the above problems, recently, cover windows using a plastic material with relatively free formability have been proposed. A cover window made of a plastic material has the advantages of being light, not easily broken, and capable of implementing various designs. Currently, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, etc. having excellent transparency are mainly used as plastic materials for cover window substrates. These materials have the advantage of excellent transparency, but the glass transition temperature is below 150 ° C. In this case, there is a problem in that a crack occurs in the hard coating layer during molding, or the entire thickness of the cover window becomes thick, making it difficult to apply to a flexible display.

On the other hand, in order to implement a flexible display, the thickness of the display device needs to be thin. Accordingly, recently, attempts have been made to reduce the thickness of the entire device by integrating a polarizing plate or a touch panel into the cover window. However, in the case of the plastic materials used as the conventional cover window, there is a problem in that the UV transmittance is high, so that the dye performing the polarization function is decomposed by the UV light, so that the degree of polarization is lowered.

The present invention is to solve the above problems, and to provide a polyimide film having a novel composition having excellent properties such as flexibility, mechanical strength, heat resistance and chemical resistance, and having low ultraviolet transmittance.

Another object of the present invention is to provide a cover window and a display device including the polyimide film as described above.

According to one embodiment, the present invention provides a polyimide film, wherein the polyimide film according to the present invention includes repeating units represented by the following [Formula 1] and [Formula 2], and has an ultraviolet transmittance of 10% or less .

[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2],

X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride,

Y ¹ and Y ² are each independently a divalent organic group derived from diamine,

At least one of X ¹ , X ² , Y ¹ and Y ² includes at least one functional group selected from the group consisting of functional groups represented by the following [Formula 3].

[Formula 3]

According to another embodiment, the present invention provides a cover window, wherein the cover window according to the present invention includes a repeating unit represented by [Formula 1] and [Formula 2], and a polyimide film having an ultraviolet transmittance of 10% or less and a polarizing layer provided on one side of the polyimide film.

According to another embodiment, the present invention provides a display device, wherein the display device according to the present invention includes a display panel and a cover window disposed on the display panel, wherein the cover window includes the [Formula 1] and a repeating unit represented by Formula 2, a polyimide film having an ultraviolet transmittance of 10% or less, and a polarizing layer provided on one side of the polyimide film.

The polyimide film of the present invention has excellent transparency, flexibility, heat resistance, tensile strength and chemical resistance, so it is suitable for a flexible display device. Decomposition of dyes in the polarizing layer is minimized to maintain excellent polarization properties.

In addition, the cover window of the present invention may implement a thin display device by integrally forming a polarizing layer and/or a touch panel on the upper and/or lower surfaces of the polyimide film.

1 is a view showing an embodiment of a cover window according to the present invention.
2 is a view showing another embodiment of a cover window according to the present invention.
3 is a view showing another embodiment of a cover window according to the present invention.
4 is a view showing an embodiment of a touch sensor according to the present invention.
5 is a diagram illustrating an exemplary embodiment of a display device according to the present invention.
6 is a view showing an embodiment of a display panel according to the present invention.
7 is a view showing another embodiment of a display panel according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the following drawings and embodiments are merely examples to allow the spirit of the present invention to be sufficiently conveyed to those skilled in the art, and the present invention is not limited by the following drawings and embodiments.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings below are exemplary, and thus the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, cases including the plural are included unless otherwise explicitly stated.

In interpreting the components, it is construed as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used.

In the case of a description of a temporal relationship, for example, when the temporal relationship is described as 'after', 'following', 'after', 'before', etc., 'immediately' or 'directly' Unless ' is used, cases that are not continuous are included.

Although the first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

Characteristic parts of each of the various embodiments of the present invention can be partially or wholly combined or combined with each other, and technically various interlocking and driving are possible, and each embodiment may be implemented independently of each other or in a related relationship. It can also be done together.

First, the polyimide film according to the present invention will be described.

As a result of repeated research to develop a film for a cover window that has excellent properties such as flexibility, mechanical strength, heat resistance and chemical resistance, and has low UV transmittance, the present inventors have a novel structure having two cyclohexyl groups in the repeating unit. of polyimide film. In the case of the transparent polyimide known so far, it was common that the visible light transmittance increased in proportion to the increase in the visible light transmittance, so that both the visible light transmittance and the ultraviolet transmittance were high. However, the polyimide film of the present invention has a characteristic that the visible light transmittance is as high as 85% or more and the ultraviolet transmittance is 10% or less.

More specifically, the polyimide film of the present invention includes repeating units represented by the following [Formula 1] and [Formula 2].

[Formula 1]

[Formula 2]

In the [Formula 1] and [Formula 2], X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride, more specifically, at least one aromatic ring, at least one alicyclic ring, tetravalent organic groups including aliphatic chains and combinations thereof.

In addition, Y ¹ and Y ² are each independently a divalent organic group derived from diamine, and more specifically, 4 including at least one aromatic ring, at least one alicyclic ring, an aliphatic chain, and combinations thereof may be an organic group.

Meanwhile, in the polyimide film of the present invention ^{, at least one of X 1} , X ² , Y ¹ and Y ² includes at least one functional group selected from the group consisting of functional groups represented by the following [Formula 3] characterized by it. According to the research of the present inventors, when the structure in which two cyclohexyl groups are bonded is included in the polyimide or polyamic acid structure, like the functional groups of the following [Formula 3], the light in the ultraviolet region is absorbed, and the light in the visible region is It has been found to exhibit selective light transmittance that transmits silver. More specifically, the polyimide film of the present invention has a light transmittance of 10% or less, preferably 5% in ultraviolet rays, for example, at a wavelength of 365 nm.

[Formula 3]

On the other hand, the polyimide film of the present invention preferably contains 5 mol% to 10 mol% of the repeating unit including the functional group represented by the above [Formula 3]. When the content of the repeating unit including the functional group represented by the above [Formula 3] is less than 5 mol%, the yellowness may increase and transparency may decrease, and if it exceeds 10 mol%, the ultraviolet transmittance may be increased. .

The polyimide film of the present invention as described above may be formed by forming a film of a polyimide resin prepared by reacting an acid dianhydride with a diamine. At this time, the acid dianhydride and/or diamine may be used by mixing two or more compounds having different structures. The functional groups indicated are included.

For example, the acid dianhydride including a functional group represented by the [Formula 3] may be a compound represented by the following [Formula 4]. In this case, in [Formula 1] and [Formula 2], X ¹ and/or X ² may be a tetravalent group derived from an acid dianhydride represented by the following [Formula 4].

[Formula 4]

In [Formula 4], R ₁ and R ₂ are each independently -O-, -S-, SO2- -SO-, -C(=O)-, or -CO ₂ -, and Q ₁ is It is a functional group selected from the group consisting of functional groups represented by [Formula 3].

[Formula 3]

In addition, the diamine including a functional group represented by the [Formula 3] may be, for example, a compound represented by the following [Formula 5], in this case, in [Formula 1] and [Formula 2], the Y ¹ and/or Y ² may be a divalent group derived from a diamine represented by the following [Formula 5].

[Formula 5]

In this case, in [Formula 5], R ₃ and R ₄ are each independently -O-, -S-, SO2- -SO-, -C(=O)- or -CO ₂ -, and the Q ₂ may be a functional group selected from the group consisting of functional groups represented by the following [Formula 3].

[Formula 3]

On the other hand, in the polyimide film of the present invention, repeating units that do not include the functional group of [Formula 3], that is, a repeating unit formed by reacting an acid dianhydride not containing the functional group of [Formula 3] and diamine more may be included.

In this case, as the acid dianhydride not containing a functional group of the above [Formula 3], for example, an aromatic acid dianhydride may be used, and more specifically, pyromellitic acid dianhydride, 3,3',4, 4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, Naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride , naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6 ,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3,6, 7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7- Tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3 ',4'-biphenyltetracarboxylic dianhydride, 3,3",4,4"-p-terphenyltetracarboxylic dianhydride, 2,2",3,3"-p-terphenyltetra Carboxylic dianhydride, 2,3,3",4"-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-propane dianhydride, 2,2- Bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-di Carboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane Dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, perylene-2,3 ,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene -5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride Water, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride Water, pyrazine-2,3,5,6-tetracarboxylic Acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-oxydiphthalic acid The dianhydride may be used alone or in combination of two or more, but is not limited thereto.

On the other hand, as the diamine that does not include a functional group of the above [Formula 3], for example, an aromatic diamine may be used, and more specifically, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl -p-phenylenediamine, 2,4-diaminomesitylene, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene -2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis[ 4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3, 3'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 3,3-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis( 4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl , 3,3'-dimethoxybenzidine, 4,4'-diamino-p-terphenyl, 3,3'-diamino-p-terphenyl, bis(p-β-amino-t-butylphenyl)ether , bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1, 5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p- Xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4 -Oxadiazole, piperazine, etc. may be used alone or in combination of two or more, but is not limited thereto.

The polyimide film of the present invention as described above has excellent UV protection performance with UV transmittance of 10% or less and high transparency. Specifically, the polyimide film of the present invention has a yellowness (YI) of 4 or less and a visible light transmittance of 85% or more, and has high transparency. Such characteristics are exhibited by the novel structure of the polyimide film of the present invention, and are characteristics not exhibited in the conventional transparent polyimide film. The polyimide film of the present invention as described above has excellent UV blocking performance, and when a polarizing layer using a dichroic dye is integrally formed, excellent polarization properties can be maintained by minimizing the decomposition of the dye of the polarizing layer by UV rays. It has excellent transparency and is suitable for application to display devices.

In addition, the polyimide film of the present invention has a glass transition temperature (Tg) of 290 ° C. or higher, preferably about 290 ° C. to 500 ° C., has high heat resistance, and has excellent flexibility, chemical resistance and mechanical strength due to the characteristics of the polyimide.

Next, the cover window of the present invention will be described.

1 shows an embodiment of a cover window of the present invention. As shown in FIG. 1 , the cover window 100 of the present invention includes the polyimide film 110 and the polarizing layer 120 of the present invention described above.

In this case, as described above, the polyimide film 110 includes repeating units represented by the following [Formula 1] and [Formula 2], and has an ultraviolet transmittance of 10% or less.

[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2], X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride, and Y ¹ and Y ² are each independently a divalent organic group derived from diamine. and ^{at least one of X 1} , X ² , Y ¹ and Y ² includes at least one functional group selected from the group consisting of functional groups represented by the following [Formula 3].

In addition, the polyimide film 110 includes 5 mol% to 10 mol% of the repeating unit including the functional group represented by the [Formula 3]. Since the specific content of the polyimide film is the same as that described above, a detailed description thereof will be omitted.

Next, the polarizing layer 120 is provided on one side of the polyimide film 110 and is a coating-type polarizing layer formed by orienting a dichroic dye in one direction. The coating-type polarizing layer may be formed by applying an alignment layer to one side of the polyimide film, imparting an alignment property to the alignment layer through rubbing or light irradiation, and then applying a dichroic dye on the alignment layer to align in a certain direction. have. In this case, the dichroic dye oriented in a certain direction absorbs polarized light vibrating in a specific direction to realize polarization performance.

More preferably, the polarizing layer may include a liquid crystal and an organic dichroic dye. In this case, the polarizing layer is formed by applying an alignment film to one side of the polyimide film, imparting an alignment property to the alignment film through rubbing or light irradiation, and then applying a mixture of a dichroic dye and liquid crystal on the alignment film to align it in a certain direction. method can be formed. When a mixture of liquid crystal and organic dichroic dye is applied on the alignment layer, the liquid crystal is first oriented by the alignment layer, and the organic dichroic dye is aligned along the liquid crystal and arranged in a certain direction, so when applied to a large area film, the dichroic dye It has the advantage of being able to form an arrangement more uniformly.

On the other hand, since the coating-type polarizing layer as described above does not require a stretching process during manufacturing, process time and manufacturing cost are saved, and a separate protective film is not required because the liquid crystal and dichroic dye layers have their own hardness. It has the advantage that it can be implemented in a thin form. The thickness of the polarizing layer 120 of the present invention may be about 10 μm to 100 μm, preferably, about 10 μm to 50 μm.

Meanwhile, in FIG. 1 , the polarizing layer 120 is illustrated as being directly formed on the polyimide film 110 , but the present invention is not limited thereto, and a hard coating layer is disposed between the polarizing layer 120 and the polyimide film 110 . , other layers or films such as a quarter wave plate or a compensation film may be interposed.

Meanwhile, FIG. 2 shows another embodiment of the cover window of the present invention. As shown in FIG. 2 , the cover window 100 of the present invention may further include a hard coating layer 130 on at least one surface of the polyimide film 110 . Since the components other than the hard coating layer 130 are the same as described above, only the hard coating layer will be described herein.

The hard coating layer 130 is for improving the surface hardness of the cover window 100 and is formed on one or both surfaces of the polyimide film 110 . Although the drawings show that the hard coating layer 130 is provided on both surfaces of the polyimide film 110 , the present invention is not limited thereto. That is, the hard coating layer may be formed only on one surface of the polyimide film. In addition, although it is illustrated in FIG. 2 that the hard coating layer 130 is formed in one layer, the present invention is not limited thereto, and the hard coating layer may have a multilayer structure of two or more layers.

On the other hand, the material of the hard coating layer is not particularly limited, and various materials used to improve the surface hardness of the plastic film in the art may be used without limitation. The thickness of the hard coating layer 130 may be, for example, about 5 μm to about 100 μm, preferably, about 6 μm to about 50 μm, but is not limited thereto.

3 shows another embodiment of the cover window of the present invention. As shown in FIG. 3 , the cover window 100 of the present invention may further include a touch panel 400 on the other side of the polyimide film 110 , that is, on the opposite side of the side on which the polarization layer 120 is provided. can Since components other than the touch panel are the same as described above, only the touch panel will be described herein.

4 shows an embodiment of the touch panel 400 according to the present invention. As shown in FIG. 4 , the touch panel 400 may be divided into a display area AA through which light is transmitted and a non-display area IA through which light is not transmitted. In detail, the display area AA means an area in which a user's touch command input is possible, and the non-display area IA is a concept opposite to the display area AA, and is not activated even when a user touches it. Therefore, it means an area where touch command input is not performed.

In the touch panel 400 , a sensing electrode 421 and a wiring 422 may be disposed on one surface of the first touch substrate 401 . In this case, the first touch substrate 401 may be a separate substrate or the polyimide film 110 of the present invention. From the viewpoint of thin implementation, the first touch substrate 401 is preferably the polyimide film 110 . In this case, the sensing electrode 421 and the wiring 422 of the touch panel 400 are polyimide It is provided on one surface of the film 110 and the touch panel 400 is integrally formed on the cover window 100 .

The sensing electrode 421 may be disposed on the display area AA, and the wiring 422 may be disposed on the non-display area IA. Although not shown in the drawings, a printed layer may be further formed in the non-display area IA of the first touch substrate 401 . Also, a wiring 422 may be formed on the printed layer.

The sensing electrode 421 may include a conductive material. For example, the sensing electrode 421 may be selected from the group consisting of a transparent conductive material, a metal, a nanowire, a photosensitive nanowire film, a carbon nanotube (CNT), graphene, a conductive polymer, and combinations thereof. may include any one.

The sensing electrode 421 may include a first sensing electrode 411 and a second sensing electrode 412 . The first sensing electrode 411 and the second sensing electrode 412 may include the same material or different materials. Also, the first sensing electrode 411 and the second sensing electrode 412 may be disposed on the same surface of the first touch substrate 401 .

When the first sensing electrode 411 and the second sensing electrode 412 are disposed on the same surface of the first touch substrate 401 , the first sensing electrode 411 and the second sensing electrode 412 are ) should not be in contact with each other. To this end, an insulating layer and a bridge electrode may be further disposed.

In detail, one sensing electrode of the first sensing electrode 411 and the second sensing electrode 412 is disposed under the insulating layer, and the other sensing electrode is disposed at both ends of the bridge electrode formed on the insulating layer. connected and may be electrically connected. Accordingly, the first sensing electrode 411 and the second sensing electrode 412 may be electrically connected to each other without being short-circuited by the bridge electrode and the insulating layer.

The first sensing electrode 411 and the second sensing electrode 412 may be disposed on the display area AA to serve as a sensor for sensing a touch. in details. The first sensing electrode 411 may be disposed to extend in one direction on the display area AA, and the second sensing electrode 412 may be disposed to extend in a direction different from the one direction.

The wiring 420 may include a first wiring 421 and a second wiring 422 . In detail, the wiring 420 may include the first wiring 421 connected to the first sensing electrode 411 and the second wiring 422 connected to the second sensing electrode 412 . have.

The first wiring 421 and the second wiring 422 may be connected to a printed circuit board (not shown). In detail, a driving chip (not shown) is mounted on the first wiring 421 and the second wiring 422 for a touch signal sensed from the first sensing electrode 411 and the second sensing electrode 412 . A touch operation may be performed by transferring the information to the printed circuit board (not shown). The printed circuit board (not shown) may be, for example, a flexible printed circuit board (FPCB).

The first wiring 421 and the second wiring 422 may include a conductive material. For example, the first wiring 421 and the second wiring 422 may include a metal material such as silver (Ag) or copper (Cu).

Although not shown in the drawing, a protective layer (not shown) may be further formed on the wiring 420 . The protective layer (not shown) may protect the wiring 420 . Specifically, the protective layer (not shown) may prevent the wiring 420 from being oxidized by exposure to oxygen or from being deteriorated in reliability due to penetration of moisture.

However, the configuration of the touch panel according to the present invention is not limited to FIG. 4 , and various changes and modifications are possible without departing from the technical spirit of the present invention.

The cover window 100 of the present invention as described above has a total thickness of 30 μm to 500 μm, which can be implemented to be thinner than the conventional cover window, so it is suitable for being applied to a flexible display. In addition, excellent polarization performance can be realized by minimizing the decomposition of the dye of the polarizing layer by ultraviolet rays by using a polyimide film having a low ultraviolet transmittance. In addition, when the polyimide film is used as a touch substrate, the thickness of the display device may be further reduced.

Next, the display device of the present invention will be described. As shown in FIG. 5 , the display device of the present invention includes a display panel 300 and a cover window 100 of the present invention disposed on the display panel. Meanwhile, since the cover window is the same as described above, only the display panel 300 will be described herein.

The display panel 300 may be a liquid crystal display panel or an organic light emitting display panel.

6 illustrates a case in which the display panel 300 is a liquid crystal display panel. As shown in FIG. 6 , the liquid crystal display panel 300 is formed by bonding a first substrate 301 and a second substrate 302 with a liquid crystal layer 380 interposed therebetween. In this case, the hard coating layer 100 may be formed by coating the surface exposed to the outside of the first substrate 301 or the second substrate 302 of the display panel 300 .

In addition, although not shown in the drawings, a backlight unit may be disposed under the liquid crystal display panel 300 .

Meanwhile, on one surface of the first substrate 301 , a gate line and a data line are disposed to cross each other perpendicularly with a gate insulating layer 352 interposed therebetween to define a pixel area. A thin film transistor (TFT) is provided in the pixel region, and the thin film transistor is connected to the pixel electrode 357 provided in each pixel region through a contact hole formed in the insulating layer 356 . That is, the first substrate 301 may be referred to as a thin film transistor substrate.

The thin film transistor TFT includes a gate electrode 351 , a gate insulating layer 352 , a semiconductor layer 353 , a source electrode 354 , and a drain electrode 355 . In addition, although the drawing shows a bottom gate structure in which the gate electrode 351 of the thin film transistor is disposed under the semiconductor layer 353, it is not limited to this structure, and the gate electrode 351 is It may be formed as a top gate structure disposed on the semiconductor layer 353 . In addition, various changes and modifications are possible to the configuration of the thin film transistor without departing from the technical spirit of the present invention.

In addition, on one surface of the second substrate 302 of the liquid crystal display panel 300 , a black grid-shaped black enclosing a pixel area while covering a non-display area in which a thin film transistor (TFT) of the first substrate 301 is disposed. A matrix 371 is formed. In addition, R (red), G (green), and B (blue) color filter layers 372 that are sequentially and repeatedly arranged to correspond to each pixel area are included in the grid, and a transparent common electrode 373 covering all of them is included. . That is, the second substrate 302 may be a color filter substrate.

A first alignment layer 358 and a second alignment layer 374 are interposed between the liquid crystal layer 380 and the pixel electrode 357 and between the liquid crystal layer 380 and the common electrode 373 , respectively. The first alignment layer 358 and the second alignment layer 374 may uniformly align the initial alignment state and alignment direction of the liquid crystal molecules.

However, the drawings are simplified illustrations of the liquid crystal display panel according to the present invention, and the present invention is not limited thereto. For example, although one thin film transistor is represented in the drawing, the thin film transistor may be composed of a combination of one or more thin film transistors depending on the characteristics of operation.

In addition, the method for controlling the arrangement of liquid crystal molecules can be variously applied to a twisted nematic (TN) mode and a vertical alignment (VA) mode, as well as an IPS (In Plane Switching) mode or FFS (Fringe Field Switching) mode. Accordingly, although the pixel electrode 357 is formed on the first substrate 301 and the common electrode 373 is formed on the second substrate 302 in the drawing, the pixel electrode 357 and the common electrode 373 are illustrated. ) may be changed or modified. In an In Plane Switching (IPS) mode or a Fringe Field Switching (FFS) mode, the pixel electrode 357 and the common electrode 373 may be formed on the first substrate 301 .

In addition, in the liquid crystal display panel 300 , a thin film transistor, a color filter layer, and a black matrix are formed on a first substrate 301 , and a second substrate 302 is formed on the first substrate 301 with the liquid crystal layer interposed therebetween. It may be a liquid crystal display panel having a color filter on transistor (COT) structure to be bonded. That is, a thin film transistor may be formed on the first substrate 301 , a protective film may be formed on the thin film transistor, and a color filter layer may be formed on the protective film. In addition, a pixel electrode in contact with the thin film transistor is formed on the first substrate 301 . In this case, in order to improve the aperture ratio and simplify the mask process, the black matrix may be omitted, and the common electrode may also serve as the black matrix.

That is, the liquid crystal display panel 300 is not limited to the representation of the drawings, and various changes and modifications are possible without departing from the technical spirit of the present invention.

Meanwhile, FIG. 7 shows a case in which the display panel 300 is an organic light emitting display panel. A case in which the display panel 300 is an organic light emitting display panel will be described with reference to FIG. 7 .

As shown in FIG. 7 , the organic light emitting display panel 300 includes a first substrate 301 on which a thin film transistor (TFT) and an organic light emitting device (OL) electrically connected to the thin film transistor (TFT) are formed; and a second substrate 302 for protecting the organic light emitting diode OL. In this case, the hard coating layer 100 of the present invention may be formed by coating the surface exposed to the outside of the first substrate 301 or the second substrate 302 of the display panel 300 .

An encapsulation layer 324 may be formed between the first substrate 301 and the second substrate 302 . Although the drawing shows the encapsulation layer 324 as a single layer, the encapsulation layer 324 may be composed of a plurality of layers, such as a protective layer and an adhesive layer.

A thin film transistor (TFT) is formed on one surface of the first substrate 301 of the organic light emitting display panel 300 . The thin film transistor TFT is formed to include a semiconductor layer 311 , a gate electrode 313 , a source electrode 315 , and a drain electrode 316 .

The semiconductor layer 311 includes a source region 311a, a channel region 311b, and a drain region 311c, a gate insulating layer 312 is formed on the semiconductor layer 311, and the gate insulating layer 312 ), a gate line and a gate electrode 313 branched from the gate line are formed. An interlayer insulating layer 314 is formed on the gate wiring and the gate electrode 313 .

A data line defining a pixel area by crossing the gate line with the interlayer insulating layer 314 interposed therebetween, a source electrode 315 branched from the data line, and a drain electrode 316 spaced apart from the source electrode 315 by a predetermined distance ) is formed. In this case, the source electrode 315 and the drain electrode 316 are connected to the semiconductor layer 311 through a contact hole formed through the interlayer insulating layer 314 and the gate insulating layer 312 formed on the gate electrode 313 . They contact the source region 311a and the drain region 311c.

A passivation layer 317 is formed on the source electrode 315 and the drain electrode 316 , and a contact hole exposing the drain electrode 316 is formed in the passivation layer 317 . The exposed drain electrode 316 is electrically connected to the connection electrode 318 formed on the passivation layer 317 . In addition, a planarization layer 319 is formed on the entire surface of the first substrate 301 including the thin film transistor (TFT), and a contact hole through which the connection electrode 318 is exposed is formed in the planarization layer 319 .

An organic light emitting diode OL electrically connected to the thin film transistor TFT is formed through the contact hole formed in the planarization layer 319 . The organic light emitting device OL includes a lower electrode 320 , an organic light emitting layer 322 , and an upper electrode 323 .

In more detail, the lower electrode 320 of the organic light emitting device OL is formed on the exposed connection electrode 318 . Although the drawing shows that the lower electrode 320 of the organic light emitting diode OL and the drain electrode 316 of the thin film transistor TFT are connected through the connection electrode 318, the connection electrode 318 is omitted, and the organic The lower electrode 320 of the light emitting device OL and the drain electrode 116 of the thin film transistor TFT may be formed in direct contact with each other through the planarization layer 319 in which the contact hole is formed.

A bank pattern 321 exposing the lower electrode 320 is formed on the lower electrode 320 in units of pixel areas. An organic light emitting layer 322 is formed on the exposed lower electrode 320 . The organic light emitting layer 322 is composed of a single layer made of a light emitting material, or a hole injection layer, a hole transporting layer, a light emitting layer, an electron transporting layer ( It may be composed of multiple layers of an electron transporting layer, and an electron injection layer.

An upper electrode 323 is formed on the organic light emitting layer 322 . When the lower electrode 320 is an anode, the upper electrode 323 is a cathode, and when the lower electrode 320 is a cathode, the upper electrode is an anode .

An encapsulation portion is formed on the first substrate 301 on which the thin film transistor TFT and the organic light emitting device OL are formed. For example, an encapsulation layer 324 for protecting display devices is formed on the upper electrode 323 . The encapsulation layer 324 may be formed of a plurality of layers, and may be bonded to the second substrate 302 . The second substrate 302 may be an encapsulation substrate for encapsulation. However, the sealing portion disposed on the first substrate 301 is not limited to the encapsulation layer 324 and the second substrate 302 , and various types of sealing are generally known to prevent the inflow of oxygen or moisture. Additional may apply.

In addition, the configuration of the display device according to the present invention is not limited to the drawings, and various changes and modifications may be made without departing from the technical spirit of the present invention.

Hereinafter, the present invention will be described in more detail through specific examples.

<Example 1>

In a 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler, 512 g of N,N-dimethylacetamide (DMAc) was filled while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 18.0 g (0.09 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA) and 3.8 g (0.01 mol) of the compound represented by [Formula 6], 2,3 29.4 g (0.1 mol) of ,3',4'-biphenyltetracarboxylic dianhydride (BPDA) was added. Then, after cooling sufficiently so that the exothermic temperature does not exceed 80° C., the mixture was stirred at 60° C. for 3 hours after the temperature was stabilized to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After completion of the reaction, the obtained polyamic acid solution was cast on a glass plate to a thickness of 500 μm to 1000 μm using a doctor blade, and then dried in a vacuum oven at 40° C. for 1 hour and at 60° C. for 2 hours to obtain a self-standing film. A polyimide film A having a thickness of 30 μm was obtained by heating in a high-temperature furnace oven at a temperature increase rate of 5° C./min at 80° C. for 3 hours, at 100° C. for 1 hour, at 200° C. for 1 hour, and at 300° C. for 30 minutes.

[Formula 6]

<Example 2>

In a 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler, 503 g of N,N-dimethylacetamide (DMAc) was filled while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 19.0 g (0.095 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA) and 1.9 g (0.005 mol) of the compound represented by [Formula 6], 2,3 29.4 g (0.1 mol) of ,3',4'-biphenyltetracarboxylic dianhydride (BPDA) was added. Then, after cooling sufficiently so that the exothermic temperature does not exceed 80 ° C., after the temperature is stabilized, the mixture is stirred at 60 ° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid content concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film B having a thickness of 30 µm.

<Example 3>

A 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 514 g of N,N-dimethylacetamide (DMAc) while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 20.0 g (0.1 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (BPDA) 26.5 g (0.09 mol) and 4.9 g (0.01 mol) of the compound represented by [Formula 7] were added. Then, it was sufficiently cooled so that the exothermic temperature did not exceed 80° C., and stirred at 60° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film C having a thickness of 30 µm.

[Formula 7]

<Example 4>

In a 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler, 504 g of N,N-dimethylacetamide (DMAc) was filled while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 20.0 g (0.1 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (BPDA) 27.9 g (0.095 mol) and 2.5 g (0.005 mol) of the compound represented by [Formula 7] were added. Then, it was sufficiently cooled so that the exothermic temperature did not exceed 80° C., and stirred at 60° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film D having a thickness of 30 μm.

<Example 5>

A 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 513 g of N,N-dimethylacetamide (DMAc) while passing nitrogen, and the temperature of the reactor was maintained at 25°C. 19.0 g (0.095 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA) and 1.9 g (0.005 mol) of the compound represented by the above [Formula 6] were completely dissolved, and 2 27.9 g (0.095 mol) of ,3,3',4'-biphenyltetracarboxylic dianhydride (BPDA) and 2.5 g (0.005 mol) of the compound represented by [Formula 7] were added. Then, after cooling sufficiently so that the exothermic temperature does not exceed 80° C., the mixture was stirred at 60° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film E having a thickness of 30 µm.

<Comparative Example 1>

A 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 494 g of N,N-dimethylacetamide (DMAc) while passing nitrogen, and the temperature of the reactor was maintained at 25°C. 20.0 g (0.1 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA) was completely dissolved, and then 2,3,3',4'-biphenyltetracarboxylic acid 29.4 g (0.1 mol) of dianhydride (BPDA) was added. Then, after cooling sufficiently so that the exothermic temperature does not exceed 80° C., the mixture was stirred at 60° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film F having a thickness of 30 μm.

<Comparative Example 2>

A 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 584 g of N,N-dimethylacetamide (DMAc) while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 10.0 g (0.05 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA) and 19.0 g (0.05 mol) of the compound represented by the above [Formula 6], 2, 29.4 g (0.1 mol) of 3,3',4'-biphenyltetracarboxylic dianhydride (BPDA) was added. Then, after cooling sufficiently so that the exothermic temperature does not exceed 80° C., the mixture was stirred at 60° C. for 3 hours after the temperature was stabilized to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film G having a thickness of 30 μm.

<Comparative Example 3>

A 1L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 602 g of N,N-dimethylacetamide (DMAc) while passing nitrogen, and the temperature of the reactor was maintained at 25°C. After completely dissolving 20.0 g (0.1 mol) of 4,4'-diaminodiphenyl ether (4,4'-OxyDiAniline, ODA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (BPDA) 14.7 g (0.05 mol) and 24.6 g (0.05 mol) of the compound represented by [Formula 7] were added. Then, it was sufficiently cooled so that the exothermic temperature did not exceed 80° C., and stirred at 60° C. for 3 hours to obtain a polyamic acid solution having a solution viscosity of 50 poise at a solid concentration of 10 Wt%.

After the reaction was completed, a film was formed in the same manner as in Example 1 using the obtained polyamic acid solution to obtain a polyimide film H having a thickness of 30 μm.

<Experimental example>

The glass transition temperature, yellowness, and light transmittance of the polyimide films A to H obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were measured. The measurement results are described in [Table 1] below, and the measurement method is as follows.

(1) Glass transition temperature (Tg): Using the DMA Q800V7.5 Build 127 device, according to the DMA method (IPC-TM-650 2.4.24.4), at a temperature profile of 30~350℃, at a heating rate of 5℃/min. measured.

(2) Light transmittance: The transmittance at a wavelength of 365 nm (ultraviolet light transmittance) and transmittance at a wavelength of 550 nm (visible light transmittance) were measured using a UV spectrometer (Varian, Cary100).

(3) Yellowness (YI): The yellowness was measured according to ASTM E313 standard.

division film Tg(℃) YI (%) UV transmittance (%) Visible light transmittance (%) Example 1 A 290 2.6 4.6 89.1 Example 2 B 305 3.1 6.7 88.9 Example 3 C 300 2.5 5.6 89.2 Example 4 D 310 3.0 7.1 88.9 Example 5 E 310 3.3 6.6 88.7 Comparative Example 1 F 350 6.8 One 84.1 Comparative Example 2 G 270 2.0 31.5 89.9 Comparative Example 3 H 280 1.9 36.4 89.7

From Table 1, it can be seen that, in the case of the polyimide films A to E prepared in Examples 1 to 5, heat resistance and transparency were excellent, and the UV transmittance was 10% or less. In contrast, the polyimide film F of Comparative Example 1 had high yellowness and low visible light transmittance, so it was not suitable for display. In the case of the polyimide films G and H of Comparative Examples 2 and 3, heat resistance and UV blocking properties It can be seen that this drop

100: cover window
110: polyimide film
120: polarizing layer
130: hard coating layer
300: display panel
400: touch panel

Claims (16)

A polyimide film comprising a repeating unit represented by the following [Formula 1] and [Formula 2], and having an ultraviolet transmittance of 10% or less.
[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2],
X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride,
Y ¹ and Y ² are each independently a divalent organic group derived from diamine,
At least one of X ¹ and X ² is a tetravalent organic group derived from an acid dianhydride represented by the following [Formula 4],
At least one of Y ¹ and Y ² is a divalent organic group derived from a diamine represented by the following [Formula 5],
[Formula 4]

[Formula 5]

In [Formula 4], R ₁ and R ₂ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₁ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3],
In [Formula 5], R ₃ and R ₄ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₂ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3].
[Formula 3]

The method of claim 1,
The polyimide film is a polyimide film comprising 5 mol% to 10 mol% of the repeating unit including the functional group represented by the [Formula 3].
The method of claim 1,
At least one of X ¹ and X ² is a tetravalent organic group derived from the acid dianhydride represented by [Formula 4],
The ^{polyimide film wherein at least one of Y 1} and Y ² is a divalent organic group derived from the diamine represented by the above [Formula 5].
delete The method of claim 1,
The polyimide film is a polyimide film having a visible light transmittance of 85% or more.
The method of claim 1,
The polyimide film is a polyimide film having a yellowness (YI) of 4 or less.
According to claim 1,
The polyimide film is a polyimide film having a glass transition temperature of 290°C or higher.
A polyimide film comprising a repeating unit represented by the following [Formula 1] and [Formula 2] and having an ultraviolet transmittance of 10% or less; and
A cover window including a polarizing layer provided on one side of the polyimide film.
[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2],
X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride,
Y ¹ and Y ² are each independently a divalent organic group derived from diamine,
At least one of X ¹ and X ² is a tetravalent organic group derived from an acid dianhydride represented by the following [Formula 4],
At least one of Y ¹ and Y ² is a divalent organic group derived from a diamine represented by the following [Formula 5],
[Formula 4]

[Formula 5]

In [Formula 4], R ₁ and R ₂ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₁ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3],
In [Formula 5], R ₃ and R ₄ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₂ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3].
[Formula 3]

9. The method of claim 8,
The polarizing layer is a cover window comprising a liquid crystal and an organic dichroic dye.
10. The method of claim 9,
A cover window further comprising a hard coating layer on at least one surface of the polyimide film.
9. The method of claim 8,
The cover window further includes a touch panel on the other side of the polyimide film.
12. The method of claim 11,
The touch panel includes a sensing electrode and a wiring,
The cover window in which the sensing electrode and the wiring are provided on one surface of the polyimide film.
9. The method of claim 8,
The cover window has an overall thickness of 30 μm to 500 μm.
9. The method of claim 8,
The polarizing layer is a cover window having a thickness of 10 μm to 100 μm.
display panel; and
a cover window disposed on the display panel;
The cover window includes a repeating unit represented by the following [Formula 1] and [Formula 2], and a polyimide film having an ultraviolet transmittance of 10% or less and a polarizing layer provided on one side of the polyimide film. Device.
[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2],
X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride,
Y ¹ and Y ² are each independently a divalent organic group derived from diamine,
At least one of X ¹ and X ² is a tetravalent organic group derived from an acid dianhydride represented by the following [Formula 4],
At least one of Y ¹ and Y ² is a divalent organic group derived from a diamine represented by the following [Formula 5],
[Formula 4]

[Formula 5]

In [Formula 4], R ₁ and R ₂ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₁ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3],
In [Formula 5], R ₃ and R ₄ are each independently -O-, -S-, SO ₂ - -SO-, -C(=O)- or -CO ₂ -, and Q ₂ is It is a functional group selected from the group consisting of functional groups represented by the following [Formula 3].
[Formula 3]

A polyimide film comprising a repeating unit represented by the following [Formula 1] and [Formula 2], and having an ultraviolet transmittance of 10% or less.
[Formula 1]

[Formula 2]

In [Formula 1] and [Formula 2],
X ¹ and X ² are each independently a tetravalent organic group derived from an acid dianhydride,
Y ¹ and Y ² are each independently a divalent organic group derived from diamine,
At least one of Y ¹ and Y ² includes at least one functional group selected from the group consisting of functional groups represented by the following [Formula 3].
[Formula 3]

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