KR101447274B1 - Folder type polarized film for organic light emitting diode - Google Patents

Abstract

The present invention relates to a foldable polarizing film for OLED. More specifically, the present invention relates to a foldable polarizing film for OLEDs having folding performance while maintaining optical properties by allowing the transparent support to be a cycloolefin polymer (COP) film and the compensation film to be a? / 4 phase-difference cycloolefin polymer film will be.

Description

[0001] The present invention relates to a folding type polarizing film for OLED,

The present invention relates to a foldable polarizing film for OLED. More particularly, the present invention relates to a foldable polarizing film for OLEDs having folding performance while maintaining optical properties by allowing the transparent support to be a cycloolefin polymer (COP) film and the compensation film to be a? / 4 phase-difference cycloolefin polymer film will be.

The polarizing film is used in and out of the liquid crystal cell for the purpose of controlling the direction of light oscillation in order to visualize the display pattern of the liquid crystal display device. In general, a polarizing film is a polarizer produced by a process such as stretching, dyeing and color correction of a polyvinyl alcohol film, a protective film laminated on at least one surface of the polarizer and protecting the polarizer, And a compensation film are stacked on each other.

1 shows the structure of a polarizing film using a polycarbonate film as a conventional compensation film. The upper transparent support 200a and the lower transparent support 200b are attached to both surfaces of the polarizer 100 through an adhesive agent (not shown in the figure) or the like, And a polycarbonate film (400) which is a polycarbonate film.

2 shows the structure of a polarizing film using a conventional cycloolefin polymer film. A transparent support as a triacetylcellulose film 200 is attached to one side of the polarizer 100 and a cycloolefin polymer film 500 is attached to the other side of the polarizer 100.

On the other hand, the folding type display device is advantageous in that it is simple to carry and can realize a large size screen. The foldable display device is used in various fields such as a mobile phone, a PMP, a navigation, an electronic book, an electronic newspaper, and the like as well as a TV and a monitor. In order to drive such a foldable display device, the polarizing film mounted in the device must also have folding performance. The demand for folding display devices is expected to increase due to the ease of portability. Therefore, it is necessary to develop a folding type polarizing film for OLED having folding performance while maintaining optical characteristics as a polarizing film.

An object of the present invention is to provide a folding polarizing film for an OLED having folding performance while maintaining optical properties.

The foldable polarizing film for OLED of the present invention comprises a polarizer; A transparent support attached to an upper surface of the polarizer; And a compensation film attached to the lower surface of the polarizer, wherein the transparent support is a cycloolefin polymer film, and the compensation film may be a cycloolefin polymer film having a? / 4 phase difference.

In one embodiment, the tensile strength of the polarizing film may be 13 kgf / mm 2 - 20 kgf / mm 2.

In one embodiment, the tensile strength of the cycloolefin polymer film as the transparent support can be 5.5 kgf / mm2-6.5 kgf / mm2.

In one embodiment, the tensile strength of the cycloolefin polymer film as the compensation film may be 6.5 kgf / mm2-7.5 kgf / mm2.

In one embodiment, the polarizing film may further comprise a pressure sensitive adhesive layer on the lower surface of the compensation film.

The present invention provides a folding polarizing film for OLED having folding performance while maintaining optical properties.

1 shows the structure of a polarizing film using a polycarbonate film as a conventional compensation film.
2 shows the structure of a polarizing film using a cycloolefin polymer film as a conventional compensation film.
3 shows one specific example of the polarizing film of the present invention.
Fig. 4 shows another specific example of the polarizing film of the present invention.
1: polarizer, 2: transparent support, 3: compensation film, 4: pressure-sensitive adhesive layer

The foldable polarizing film for OLED of the present invention comprises a polarizer; A transparent support attached to an upper surface of the polarizer; And a compensation film attached to a lower surface of the polarizer, wherein the transparent support is a cycloolefin polymer film, and the compensation film may be a cycloolefin polymer film having a? / 4 phase difference.

3, the polarizing film of the present invention comprises a polarizer 1, a transparent (transparent) film laminated on the upper surface of the polarizer 1, A support 2 and a compensating film 3 laminated on the lower surface of the polarizer 1. In the present specification, the upper side (face) and the lower side (face) are names attached for convenience in reference to the upper and lower sides in the drawing, and the names are not necessarily used for the upper and lower surfaces.

The polarizing film of the present invention can have a folding performance when the curvature radius is 5 mm or less, preferably 3-5 mm. In this specification, the term 'folding performance' means that the folded portion is not whitened when the polarizing film is folded over 1000 times, preferably 1000 to 50000 times, more preferably 10000 to 50000 times, with a radius of curvature of 5 mm or less. This folding capability can also drive the OLEDs when using polarizing films in OLEDs.

The polarizing film of the present invention may have a tensile strength of 13 kgf / mm 2 to 20 kgf / mm 2. The tensile strength refers to a maximum stress until the film is broken by a tensile load. While increasing the tensile strength can provide foldable performance, at the same time it is necessary to maintain optical properties for use in OLED applications. The polarizing film of the present invention has tensile strength of 13 kgf / mm 2 to 20 kgf / mm 2, so that it can have folding performance while maintaining optical properties. Tensile strength can be measured with conventional strain-stress curves, but is not limited thereto.

In the polarizing film of the present invention, the transparent support may be a cycloolefin polymer film. The tensile strength of the cycloolefin polymer film may be 5.5 kgf / mm 2 to 6.5 kgf / mm 2. Within this range, the polarizing film may have folding performance. The cycloolefin polymer film can have a Ro of 0 nm-1 nm at a wavelength of 550 nm and a Rth of 0 nm-5 nm.

In the polarizing film of the present invention, the compensation film may use a cycloolefin polymer film of? / 4 phase difference having an optical axis which is 45 ° or 135 ° different from the polarizing axis of the polarizer. When a? / 4 retardation film is applied to a transparent support, it can not be used for OLED applications. The tensile strength of the cycloolefin polymer film may be 6.5 kgf / mm 2 to 7.5 kgf / mm 2. Within this range, the polarizing film may have folding performance. The cycloolefin polymer film may have a Ro of 138 nm-142 nm at a wavelength of 550 nm and a Rth of 154 nm-158 nm.

In the polarizing film of the present invention, the compensation film can be attached to the liquid crystal shell.

In the present invention, a cycloolefin polymer film having a phase difference of 0 is applied to a transparent support, and a compensation film is made of an optical film including a transmittance, polarization degree, cross transmittance, etc. of a polarizing film by applying a cycloolefin polymer film having a retardation of? And can be applied to an OLED having a folding performance while maintaining the properties.

The elements constituting the polarizing film will be described as follows.

The polarizer is made of a polyvinyl alcohol film and is not particularly limited as long as it is a polyvinyl alcohol film regardless of the manufacturing method. For example, a polarizer may be a modified polyvinyl alcohol film such as a partially-formalized polyvinyl alcohol film or an acetoacetyl-modified polyvinyl alcohol film.

The polymerization degree of polyvinyl alcohol is preferably 2400-4000. Within this range, it can function as a polarizing substrate and does not deviate from its optical properties when manufactured into a polarizing film.

Polarizers are prepared by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching it in a certain direction. Specifically, it is produced through a swelling process, a dyeing step, a stretching step and a crosslinking step. Methods of performing each step are commonly known to those skilled in the art. The thickness of the polarizer is not particularly limited, but may preferably be 20 占 퐉 to 30 占 퐉.

The transparent support is a film that supports and protects the polarizer, and should be optically transparent, free of birefringence, and high in heat resistance and mechanical strength to physically support and protect the polarizer. In addition, it should have a property of being able to adhere well with an adhesive or a pressure-sensitive adhesive. The thickness of the transparent support is not particularly limited, but may preferably be 10 占 퐉 to 40 占 퐉.

Between the polarizer and the transparent support, an adhesive layer (not shown in Fig. 3) for bonding the polarizer and the transparent support may be formed. The adhesive used for forming the adhesive layer may be an adhesive composed of a polyvinyl alcohol polymer or a water-soluble crosslinking agent of a polyvinyl alcohol polymer such as boric acid or borax, glutaraldehyde, melamine or oxalic acid, or the like.

An adhesive layer (not shown in FIG. 3) may be formed between the polarizer and the compensation film to bond the polarizer and the compensation film. As the adhesive used for forming the adhesive layer, an adhesive composed of a (meth) acrylic polymer can be used.

The thickness of the compensation film may be the same as or different from that of the transparent support. The thickness of the compensation film is not particularly limited, but may preferably be 10 占 퐉 to 40 占 퐉.

The polarizing film of the present invention may further comprise a pressure-sensitive adhesive layer for adhering to the liquid crystal cell on the lower surface of the compensation film. 4 shows a polarizing film according to another embodiment of the present invention. According to Fig. 4, a polarizing film having a pressure-sensitive adhesive layer 4 adhered to the lower surface of the compensation film 3 is shown. As the pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives such as (meth) acrylic, silicone, polyester, polyurethane, polyether or rubber can be used. It is desirable to use a pressure-sensitive adhesive having a low moisture absorption rate and good heat resistance in order to prevent peeling or peeling due to moisture absorption and to prevent chemical characteristics due to thermal expansion difference and to prevent warpage of the liquid crystal cell. For example, it can be formed by a method of forming a release coat by a releasing agent such as (meth) acrylic, silicone, acrylic silicone, polyester, heat resistant rubber, long chain alkyl, fluorine, molybdenum sulfide or the like.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example  1: Production of polarizing film

A polyvinyl alcohol film having a thickness of 60 占 퐉 was immersed in an aqueous iodine solution at 40 占 폚, stretched 5 times, and dried at 80 占 폚 for 10 minutes to obtain a polarizer. (EG-film at 550 nm, Ro = 1 nm, Rth = 5 nm, tensile strength of 6.4 kgf / mm < 2 >, Xeon yarn) having a thickness of 22 [ (ZD12-141158-A1340, 550 nm, Ro = 140 nm, Rth = 156 nm, NZ = 1.6, tensile strength of 6.9 kgf / mm2, Xeon Co., Ltd.) having a thickness of 30 μm and a thickness of 33 μm were laminated on a polyvinyl alcohol- Z-320 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) to obtain a polarizing film. The tensile strength of the polarizing film was 13.2 kgf / mm < 2 >. The tensile strength of the polarizing film was measured with a texture analyzer, TA.XT puls (manufacturer: Stable Micro system).

Comparative Example  1: Production of polarizing film

A polarizing film was obtained in the same manner as in Example 1 except that a triacetylcellulose film (tensile strength: 11.7 kgf / mm 2) was used on the upper surface of the polarizer. The tensile strength of the polarizing film was 8.9 kgf / mm < 2 >.

Comparative Example  2: Production of polarizing film

A polarizing film was obtained in the same manner as in Example 1 except that a triacetylcellulose film (phase difference:? / 4, tensile strength: 6.9 kgf / mm 2) was used for the lower surface of the polarizer. The tensile strength of the polarizing film was 11.0 kgf / mm < 2 >.

Experimental Example : Measurement of physical properties of polarizing film

(1) Folding performance survey

When the polarizing films prepared in Examples and Comparative Examples were folded in the number of times shown in Table 1 with a radius of curvature of 5 mm, whether or not the polarizing film was not deformed while being mounted on the OLED was evaluated as? And?. The case where the polarizing film was not deformed and the case where it was driven when mounted on the OLED was evaluated as "? &Quot;, and the case where the polarizing film was deformed and not driven when mounted on the OLED was evaluated as x. The results are shown in Table 1 below.

Folds Example 1 Comparative Example 1 Comparative Example 2 1,000 times ○ ○ ○ 10,000 times ○ × × 15,000 times ○ × × 50,000 times ○ × ×

As shown in Table 1, it can be seen that the polarizing film of the present invention can be driven for OLED applications without deforming the polarizing film even when the polarizing film has a radius of curvature of 5 mm and a folding number of 10000 or more. On the other hand, it can be seen that the polarizing film of Comparative Example 1-2 was deformed at the number of times of folding 10,000 times.

(2) Investigation of optical characteristics

The polarizing films prepared in the above Examples and Comparative Examples were attached to a holder of an optical property measuring instrument (V-7100, Jasco), and fitted to the sample stage. Consider the direction of light when the actual polarizing film is used and experiment in the same direction. Close the sample stage and set the program to match the optical axis. Transmittance, cross transmittance and polarization degree were obtained from the measurement data derived from the program, and the results are shown in Table 2.

Example 1 Comparative Example 1 Comparative Example 2 Transmittance (%) 41.53 42.59 42.82 Cross transmittance (%) 0.0009 0.0011 0.0019 Polarization degree (%) 99.9970 99.997 99.9948

As shown in Table 2, it can be seen that the polarizing film of the present invention maintains the optical characteristics of the conventional polarizing film, such as transmittance and polarization degree, unchanged.

Claims (6)

A polarizer;
A transparent support attached to an upper surface of the polarizer; And
A compensation film attached to a lower surface of the polarizer;
And a polarizing film,
The transparent support is a cycloolefin polymer film,
The compensation film is a cycloolefin polymer film of? / 4 phase difference,
Wherein the polarizing film has a tensile strength of 13 kgf / mm ² -20 kgf / mm ² . delete The method of claim 1, wherein the transparent supporting chain tensile strength of the cyclo-olefin polymer film is a polarizing film for OLED, characterized in that ^{5.5kgf / mm 2 -6.5kgf / mm 2} . The method of claim 1, wherein the compensation film of λ / 4 phase difference tensile strength of the cyclo-olefin polymer film is a polarizing film for OLED, characterized in that ^{6.5kgf / mm 2 -7.5kgf / mm 2} . The polarizing film for OLED of claim 1, further comprising an adhesive layer between the transparent support and the polarizer and between the polarizer and the compensation film. The polarizing film for OLED of claim 1, wherein the OLED polarizing film further comprises a pressure-sensitive adhesive layer on a lower surface of the compensation film.

Images