WO2019066368A1

WO2019066368A1 - Flexible film

Info

Publication number: WO2019066368A1
Application number: PCT/KR2018/011060
Authority: WO
Inventors: 이진국; 박진영; 정순화; 장영래; 서정현; 김혜민
Original assignee: 주식회사 엘지화학
Priority date: 2017-09-28
Filing date: 2018-09-19
Publication date: 2019-04-04

Abstract

The present invention relates to a flexible film and, more specifically, to a flexible film having excellent flexibility while exhibiting high hardness. The flexible film of the present invention exhibits flexibility, bendability, high hardness, abrasion resistance, and high transparency, and is less likely to be damaged even when repeatedly warped or folded for a long time, such that the flexible film can be usefully applied to a flexible mobile device, a display device, a front panel of a dashboard, a display unit, etc.

Description

Title of the Invention

Flexible film

TECHNICAL FIELD

Related application (mutual quotation with field

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0126592 filed on September 28, 2017, and Korean Patent Application No. 10-2018-0111632 filed on September 18, 2018, The entire contents of which are incorporated herein by reference.

The present invention relates to a flexible film. More particularly, the present invention relates to a flexible film having excellent flexibility and inner layer rigidity while exhibiting high hardness.

TECHNICAL BACKGROUND OF THE INVENTION

With the recent development of mobile devices such as smart phones and tablet PCs, thinner and slimmer display substrates have been required. Glass or tempered glass is generally used as a material having excellent mechanical properties on a display window or a front plate of such a mobile device. However, glass causes a weight of the mobile device due to its own weight to be heavy, and there is a problem of breakage due to external stiffness.

Plastic resins are being studied as a substitute for glass. Plastic resin films are lightweight and less susceptible to breakage, making them suitable for trends toward lighter mobile devices. In particular, a film for coating a hard coating layer made of a plastic resin on a supporting substrate to achieve a film having properties of hardness and abrasion resistance has been proposed.

A method of increasing the thickness of the hard coat layer by a method of improving the surface hardness of the hard coat layer can be considered. In order to secure enough surface hardness to replace glass, it is necessary to implement a certain hard coating layer thickness. However, as the thickness of the hard coat layer is increased, the surface hardness can be increased. However, the hard coat layer hardens and shrinks to form wrinkles and curls And at the same time, cracking or peeling of the hard coat layer tends to easily occur, so that it is not easy to apply it practically.

Korean Patent Publication No. 2010-0041992 discloses a plastic film composition using a binder resin containing an ultraviolet ray-curable polyurethane acrylate oligomer excluding a monomer. However, the plastic film disclosed above is not superimposed on the strength to replace the glass panel of the display with a pencil hardness of about 3H.

On the other hand, displays that are bent or flexed flexibly due to aesthetic and functional reasons have recently been attracting attention, and this trend is especially noticeable in mobile devices such as smart phones and tablet PCs. However, since glass is not suitable for use as a cover plate for protecting such a flexible display, it needs to be replaced with a plastic resin or the like. However, it is difficult to fabricate a film having a high degree of glass-like hardness and a layered flexibility and an inner layer hardness for damage.

DISCLOSURE OF THE INVENTION

[Problem to be solved]

In order to solve the above problems, the present invention provides a flexible film having excellent flexibility and inner layer rigidity while exhibiting high hardness.

MEANS FOR SOLVING THE PROBLEMS

In order to solve the above problems,

A support substrate;

A first coating layer formed on one surface of the support substrate, the first coating layer comprising a first crosslinked copolymer of one or more different 3 to 6 functional acrylate binders, and inorganic fine particles; And

A second crosslinked aerial member formed on the back surface of the supporting substrate and having at least one kind of a different 3 to 6 functional acrylate binder, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder, And a second coating layer comprising a coalescent, The elastic modulus of the second coating layer measured in accordance with ASTM D882 in the state where the crab 2 coating layer is peeled from the supporting substrate is 400 to 650 MPa, the thickness of the first coating layer is 20 to 20, the thickness of the second coating layer is 20 to 150,

Wherein the ratio of the thickness of the first coating layer to the thickness of the second coating layer is 1: 1 to 1: 5.

【Effects of the Invention】

According to peulreksa block the film of the present invention, flexibility, flexibility, hardness, scratch _resistance: he represents the transparency, repetitive, continuous bending and less damage to the film in a long time folded state Ventura Double (bendable), the flexible (flexible), the It can be applied to a rollable or foldable mobile device, a display device, a front plate of various instrument panels, a display portion, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic view illustrating a method of performing a dynamic folding test on a film according to an embodiment of the present invention.

2 is a schematic illustration of a method of performing a dent test on a film according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the flexible film of the present invention,

A support substrate; A first coating layer formed on one surface of the support substrate, the first coating layer comprising a first crosslinked copolymer of one or more different 3 to 6 functional acrylate binders, and inorganic fine particles; And a second crosslinking agent which is formed on the back surface of the supporting substrate and comprises at least one kind of a different 3 to 6 functional acrylate binder, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder, And a second coating layer comprising a copolymer, wherein the second coating layer is peeled off from the support substrate , The elastic modulus of the second coating layer measured in accordance with ASTM D882 is 400 to 650 MPa, the thickness of the first coating layer is 20 to 70 m and the thickness of the second coating layer is 20 to 150 / The ratio of the thicknesses of the first coating layer and the crab coating layer is 1: 1 to 1: 5.

In the present invention, the terms first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

Moreover, the terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises", "comprising", or "having" are used to designate the presence of stated features, steps, components, or combinations thereof, and are not intended to preclude the presence of one or more other features, Components, or combinations thereof, as a matter of convenience, without departing from the spirit and scope of the invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Throughout the present specification, the acrylate egg, acrylate as well as methacrylate, or a derivative having a substituent introduced into acrylate or methacrylate are all included.

Hereinafter, the flexible film of the present invention will be described in more detail. A flexible film according to an embodiment of the present invention includes: a support substrate; A first coating layer formed on one side of the supporting substrate, the first coating layer comprising at least one first crosslinked copolymer having 3 to 6 functional acrylate bridges crosslinked, and inorganic fine particles; And at least one kind of 3 to 6 functional acrylate binder, at least one difunctional Acrylate binder, and a second crosslinked copolymer comprising a crosslinked 2 to 4-functional urethane acrylate binder, wherein the crab 2 coating layer is peeled from the supporting substrate, and ASTM D882 Wherein the thickness of the first coating layer is 20 to 150 m, the elastic modulus of the second coating layer measured based on the first coating layer is 400 to 650 MPa, the thickness of the first coating layer is 20 to 20, The ratio of the thickness of the coating layer is 1: 1 to 1: 5.

In the present invention, " flexible " refers to a state in which a crack is not generated at a length of 3 cm or more when a folding apparatus is repeated 100,000 times in a folding facility having a curvature radius of 2.5 mm And thus the flexible film of the present invention is _{applicable to a cover} film of a bendable, flexible, rollable, or foldable display.

In the flexible film of the present invention, the supporting substrate on which the coating layer is formed preferably has an elastic modulus of about 4 GPa or more as measured according to ASTM D882 so as to secure flexibility and hardness, 100, the transparent plastic resin for optical use can be used without any particular limitation in the production method and material of the supporting substrate such as stretched film or non-stretched film.

The elastic modulus of the condition of the supporting substrate is about 4 GPa or more,

5 GPa, or about 5.5 GPa, or about 6 GPa or more, and the upper limit value may be about 9 GPa or less, or about 8 GPa or less. If the elastic modulus is less than 4 GPa, the layered hardness may not be achieved, and if it is more than 9 GPa, it may be difficult to form a flexible film.

The thickness of the support substrate may be about 10 or more, or about 20 or more, or about 30 or more, and the upper limit may be about 100 or less, or about 80 or less. If the thickness of the supporting substrate is less than 10 / m, there is a risk of breakage or curl in the coating layer forming step, and it may be difficult to attain the failure degree. On the other hand, if the thickness exceeds 100 / ml, flexibility may be reduced and formation of a flexible film may be difficult. From the viewpoint of ensuring the processibility for the flexible film and balancing the properties of the hardness and the flexibility, the plastic film of the present invention has elastic modulus of not less than 4 GPa and not more than 9 GPa and a thickness of 10 to 100 ffli A substrate can be used.

More specifically, according to an embodiment of the present invention, the supporting substrate may be formed of a material such as polyimide (PI), polyimideamide, poly (PEEK), polyetheretherketone (PEEK), cyclic olefin polymer (PEEK), polyethylene terephthalate (PET), polyethylenenaphthalate , COP), polyacrylate (PAC), polymethylmethacrylate (PMMA), or triacetylcellulose (TAC). The supporting substrate may be a single layer or a multi-layer structure including two or more substrates made of the same or different materials as needed, and is not particularly limited.

Alternatively, according to an embodiment of the present invention, the supporting substrate may be formed of a material selected from the group consisting of polyimide (PI), polyimideamide, polyamide, polyimide (PI), polyimideamide polyimideamide, polyamide, and the like.

The flexible film of the present invention includes a first coating layer formed on one side of the supporting substrate and a second coating layer formed on the back side of the supporting substrate, that is, the opposite side where the crazing coating layer is formed.

First, the first coating layer comprises a crosslinked first crosslinked copolymer of one or more different 3 to 6 functional acrylate binders, and inorganic fine particles. It is preferable that the first coating layer is disposed on the upper side, that is, on the side closer to the user side when the flexible film of the present invention is applied to the other device or device alone. The first coating layer contains the first crosslinked polymer and the inorganic fine particles, which are crosslinked and polymerized with each other, of the three to six functional acrylate binders, so that the high hardness property can be imparted to the flexible film of the present invention. The modulus of elasticity measured in accordance with ASTM D882 in the state that the coating layer is peeled from the supporting substrate is not particularly limited, but it may be lGPa or more.

According to one embodiment of the present invention, the 3 to 6 functional acrylate binder is selected from the group consisting of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trioxytriacrylate (TMPEOTA), glycerin propoxylated triacrylate (GPTA), pentaerythritol tetraacrylate (PET A), dipentaerythritol pentaacrylate (DPEPA), dipentaerythritol hexaacrylate (DPHA) and the like. It is not.

The first crosslinked polymer is a polymer obtained by polymerizing at least one kind, or at least two kinds, or at least three kinds of these three or more functional acrylate binders.

According to one embodiment of the present invention, the first crosslinked polymer is a copolymer of trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETA), and dipentaerythritol pentaacrylate (DPEPA) And may be cross-linked.

According to one embodiment of the present invention, the 3- to 6-functional acrylate binder has a weight average molecular weight (Mw) of about 200 to about 2,000 g / mol, or about 200 to about 1,000 g / mol, And can range from about 600 g / m 2 to about 600 g / m 2.

Also, according to one embodiment of the present invention, the 3- to 6-functional acrylate binder has an acrylate equivalent weight of about 50 to about 300 g / mol, or about 50 to about 200 g / mol, counter 50 to about 150 g / m ^• can range.

When the weight average molecular weight and the acrylate equivalent of the 3 to 6 functional acrylate binders are within the respective ranges described above, A first coating layer can be formed.

The first coating layer includes inorganic microparticles in addition to the first crosslinked copolymer.

As the inorganic fine particles, there may be used inorganic fine particles having a nanoscale particle size, for example, nanoparticles having an average particle diameter (d50) of about 100 nm or less, about 10 to about 100 nm, or about 10 to about 50 nm. As the inorganic fine particles, for example, silica fine particles, aluminum oxide particles, titanium oxide particles, zirconia oxide particles, or zinc oxide particles can be used.

By including the inorganic fine particles, the hardness of the first coating layer can be further improved.

The first coating layer may contain 40 to 80 parts by weight of the first crosslinked copolymer and 20 to 60 parts by weight of the inorganic fine particles with respect to 100 parts by weight of the first coating layer.

Also, the thickness of the first coating layer may be from about 20 to about 70 [mu] m, or from about 20 to about 60 / [Lambda] P, or from about 30 to about 50. If the thickness of the first coating layer is less than 20 1, the surface hardness may be lowered. If the thickness of the first coating layer is more than 70, the flexibility of the flexible film of the present invention may not be good.

The first coating layer having a composition and a thickness as described above exhibits a high hardness so that the flexible film of the present invention including it can exhibit sufficient surface hardness.

In the flexible film of the present invention, the second coating layer is provided on the back surface of the supporting substrate, that is, on the opposite surface where the first coating layer is formed.

Wherein the second coating layer comprises a second crosslinked copolymer having at least one different from 3 to 6 functional acrylate binders, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder cross-linked, , Flexibility and impact resistance properties can be imparted to the flexible film of the present invention.

The second coating layer may have a modulus of elasticity of about 400 to about 650, as measured according to ASTM D882, MPa, or from about 450 to about 650 MPa, or from about 500 to about 650 MPa, or from about 500 to about 600 MPa.

If the coefficient of elasticity of the second coating layer is less than 400 MPa, strong curling may occur in the direction of the first coating layer during the production of the film. If the elastic modulus of the second coating layer is more than 650 MPa, A crack may occur when folding 100,000 folds. Therefore, when the elastic modulus of the second coating layer is in the above-mentioned range, more optimized physical properties can be secured in terms of hardness and flexibility.

When the second coating layer simultaneously satisfies the composition of the binder and the modulus of elasticity, flexibility and dynamic folding characteristics can be more effectively expressed in the flexible film of the present invention.

It is preferable that the second coating layer is disposed on the lower side, that is, the side closer to the other device side when the flexible film of the present invention is applied to the other device or device alone.

The binder of the second crosslinked copolymer of the second coating layer includes a 3 to 6 functional acrylate binder, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder.

The 3 to 6 functional acrylate binders may be the same as or different from those used in the first coating layer. For example, the 3 to 6-functional acrylate-based binder propane triacrylate to trimethylolpropane acrylate (TMPTA), hydroxy triacrylate to trimethylolpropane (TMPEOTA), glycerol propoxylated triacrylate _(GPTA): pentaerythrityl (PETA), dipentaerythritol pentaacrylate (DPEPA), dipentaerythritol hexaacrylate (DPHA), and the like, but the present invention is not limited thereto.

The second crosslinked polymer is a 3- to 6-functional acrylate-based binder, and may include one or more kinds of different kinds, or two or more types, or three or more types. For example, according to one embodiment of the present invention, the second crosslinked polymer is obtained by reacting trimethylolpropane triacrylate (TMPTA), pentaerythritol with tetraacrylate (PETA) as the 3- to 6-functional acrylate binder, , And The dipentaerythritol may include pentacrylylate (DPEPA), but the present invention is not limited thereto.

The bifunctional acrylate binder may be selected from the group consisting of triethylene glycol diacrylate (TEGDA), tetraethylene glycol diacrylate (TTEGDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA) But are not limited to, polyethylene glycol diacrylate (PEGDA), ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), diethylene glycol diacrylate (DEGDA), butanediol diacrylate (BDDA) or nucleic acid diol diacrylate (HDDA), but the present invention is not limited thereto.

According to one embodiment of the present invention, the 2- to 4-functional urethane acrylate binder has a weight average molecular weight (Mw) of about 400 to about 20,000 g / mol, or about 400 to about 15,000 g / mol, or about 1,000 To about 3,000 g / mc > l.

According to an embodiment of the present invention, the 2- to 4-functional urethane acrylate binder may have an acrylate equivalent weight of about 100 to about 10,000 g / mol, or about 200 to about 5,000 g / mol, or A range of from about 200 to about 4,000 g / mol or from about 500 to about 1,000 g / m 2 may be desirable for optimization of the properties of the second coating layer.

It may not be the 2 to 4-functional ^{polyurethane,} acrylate-based acrylate equivalent weight is too high, the hardness of the coating layer of the binder is cheungbun, if the equivalent weight is low, the hardness may be improved, but the decrease in flexibility. From the viewpoint of harmonization of the hardness and the flexibility as described above, the above-mentioned equivalence range may be preferable.

As the above-mentioned 2- to 4-functional urethane acrylate binders,

TA-604AU (manufacturer: NOF CORPORATION) or PU2100, PU210, PU3200, PU3400, PU3450 (PU series, manufacturer: Miwon) can be used, but the present invention is not limited thereto.

The second crosslinked copolymer may contain at least one of the above-mentioned three to six functional acrylate binders, a bifunctional acrylate binder, and two to four functionalities Urethane acrylate binder is a polymer crosslinked with.

As described above, the second coating layer includes the crosslinked polymer of the three kinds of binders, so that it is possible to impart excellent flexibility and inner layer rigidity to the flexible film of the present invention.

According to an embodiment of the present invention, the 3 to 6 functional acrylate binder may be used in an amount of 20 to 80 parts by weight and the bifunctional acrylate binder may be used in an amount of 10 to 40 parts by weight per 100 parts by weight of the second crosslinked copolymer. And 10 to 70 parts by weight of the 2 to 4 functional urethane acrylate binder. .

Or 60 to 90 parts by weight of the third to sixth functional acrylate binders and the second to fourth functional urethane acrylate binders, based on 100 parts by weight of the second crosslinking copolymer, and the bifunctional acrylate series And 10 to 40 parts by weight of the binder.

As described above, the second coating layer contains a second crosslinked copolymer in which one or more of a 3 to 6 functional acrylate binder, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder are cross-linked with each other , The flexible film of the present invention can achieve sufficient flexibility and impact resistance.

In addition, the thickness of the second coating layer may be from about 20 to about 150, or from about 30 to about 120 [mu] m, or from about 30 to about 100.

When the composition, thickness, and elastic modulus range of the crab coating layer are in the above-mentioned ranges, particularly when the film is repeatedly warped or folded for a long time due to high durability against bending, rolling or folding, It is possible to secure a very good folding property with less risk of damage to the substrate.

In addition, in the flexible film of the present invention, the ratio of the thicknesses of the first coating layer and the second coating layer is from about 1: 1 to about 1: 5, or from about 1: 1 to about 1: 4, About 1: 3. If the ratio of the thicknesses of the crab coating layer and the second coating layer is less than 1: 1, strong curling may occur in the direction of the first coating layer, and if it exceeds 1: 5, curling may occur in the direction of the second coating layer have. The above-mentioned curl phenomenon causes defects in the point / adhesion with other devices, films, and layers that contact the other films, films, layers, etc., of the film of the present invention Therefore, when the ratio of the thicknesses of the first coating layer and the second coating layer is in the above-mentioned range, more optimized physical properties can be secured in terms of processability.

In addition, the first and second coating layers may contain a surfactant, a UV absorber, a UV stabilizer, a yellowing inhibitor, a leveling agent, an antifouling agent, a dye for improving the color value, etc., in addition to the binder, the inorganic fine particles, the photoinitiator, May further comprise additives commonly used in the art. The content is not particularly limited as it can be variously controlled within a range that does not deteriorate the physical properties of the coating layer of the present invention. For example, about 100 to about 100 parts by weight of each of the first and second coating layers is about 0.01 to about 10 By weight.

According to an embodiment of the present invention, for example, the first and second coating layers may contain a surfactant as an additive, and the surfactant may be selected from the group consisting of 1 to 2 functional blend-based acrylates, fluorinated surfactants, May be active. At this time, the surfactant may be dispersed or crosslinked in the first and second coating layers.

The UV absorber may include a benzophenone-based compound, a benzotriazole-based compound, or a triazine-based compound. Examples of the UV stabilizer include tetramethylpiperazine Tetramethyl piperidine, and the like.

The first and second coating layers of the present invention as described above can be formed by applying a coating composition containing the above-described components onto a substrate and photo-curing the coating composition.

Examples of the photoinitiator include 1-hydroxy-cyclohexyl-p-ketone,

Hydroxy-2-methyl-1-phenyl-1-propanone,

2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-

Methyl benzoyl formate, alpha, alpha -dimeroxy-alpha-phenylacetophenone,

2-benzoyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl]

Methyl-1- [4- (methylcio) phenyl] -2- (4-morpholinyl)

Diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide, or bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. But is not limited to. Products currently on the market include Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur MBF, Irgacure 819, Darocur TPO, Irgacure 907 and Esacure KIP 100F. These photoinitiators may be used alone or in combination of two or more. remind. Examples of the organic solvent include alcohol solvents such as methanol, ethanol, isopropyl alcohol and butanol, 2-methoxyethane, 2-ethoxyethane, alkoxy alcohol solvents such as 1-methoxy-2-propanol, Ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone methyl propyl ketone and cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethyl ethyleneneglycolicol monomonoethyl ethyl ether ether, ethylene Glycol monopropyl ether ethylene glycol monobutyl ether diethylene glycol monomethyl ether diethyl glycol monoethyl ether diethyl glycol monopropyl ether diethyl glycol monobutyl ether ether solvents such as diethylene glycol-2-ethyl n-butyl ether, benzene, Can be used singly or in combination as an aromatic solvent such as rubrene and xylene.

The content of the organic solvent may be varied within a range that does not deteriorate the physical properties of the coating composition, so that the weight ratio of the solid content: organic solvent to the solid content of the components contained in the coating composition is about 30: 70 to about 99: 1. And may have appropriate fluidity and applicability when the organic solvent is in the above range.

The coating composition may be sequentially coated on the front and back surfaces of the support substrate, or simultaneously on both sides of the support substrate. According to one embodiment of the present invention, a flexible film of the present invention can be obtained by coating a coating composition containing the above-mentioned components on both sides of the above-mentioned support substrate and then photo-curing to form a coating layer. In this case, the method of applying the coating composition is not particularly limited as long as it can be used in the art to which the present technology belongs. For example, a bar coating method, a knife coating method, a coating method, a blade coating method, Gravure coating method, comma coating method, slot die coating method, lip coating method, and solution casting method. According to an embodiment of the present invention, the flexible film may include a plastic film, an adhesive film, a release film, a conductive film, a conductive layer, a liquid crystal material, and the like between at least one coating layer of at least one of the first and second coating layers, Layer, a coating layer, a cured resin layer, a non-conductive film, a metal mesh layer or a layer such as a patterned metal layer, a film, or a film. Further, the layer, film, film or the like may be in any form of a single layer, a double layer or a laminate type. The layer, film, or film may be laminated on the coating layer by a method such as lamination, coating, deposition, or sputtering using an adhesive or an adhesive film. However, But is not limited thereto. The flexible film according to the present invention can be produced, for example, by the following method.

According to one embodiment of the present invention, first coating and first photocuring of the coating composition for forming the first coating layer is performed on one side of the supporting substrate, and then coating is performed on the other side of the supporting substrate, And the second coating and the second photocuring of the composition.

In the case of forming the coating layer in this manner, since the ultraviolet ray irradiation is performed on the opposite side of the surface to which the first coating composition is applied in the second photo-curing step, the curl that may be caused by the hardening shrinkage in the first photo- A flat flexible film can be obtained. Therefore, an additional planarization process is unnecessary.

However, the present invention is not limited thereto. The curl balance may be adjusted by forming the coating composition on both sides of the supporting substrate at the same time and curing the coating composition.

The flexible film of the present invention exhibits excellent durability and stability for excellent flexibility, flexibility, hardness, scratch resistance, high transparency, bending, curling or folding and is excellent in bendable, flexible, A cover film of a next generation display having rollable or foldable characteristics, and the like can be used.

In the flexible film of the present invention, the first coating layer is coated with a pencil When scratched, the pencil hardness of the first coating layer may be 6H or more, or 7H or more. In the flexible film of the present invention, both sides of the flexible film were folded at 80 to 90 degrees with respect to the bottom surface at intervals of 5 mm in the middle of the film with the second coating layer facing the bottom, repeated 100,000 times at room temperature , It is possible to exhibit excellent dynamic folding characteristics to such an extent that no more than 3 cm of clearance is generated.

In addition, the flexible film of the present invention is more than the light transmittance 88.0%, or more than 90.0%, the haze can be less than 1.5%, or 1.0 ^_0/0 or less, or 0.5%.

Such a flexible film of the present invention can be utilized in various fields. For example, it is possible to use not only a flat shape but also a curved, bendable _: flexible, rollable or foldable mobile communication terminal, a touch of a smartphone or a tablet PC Panels, and cover substrates or element substrates of various displays.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

Preparation Example of Coating Composition

Production Example 1

10 parts by weight of trimethylolpropane triacrylate (TMPTA), 30 parts by weight of pentaerythritol tetraacrylate (PETA), 20 parts by weight of dipentaerythritol pentacrylate (DPEPA), 20 parts by weight of silica particles (MEK-AC-2140z , 40 parts by weight of a surfactant (manufactured by Nissan Chemical Co., Ltd.), 0.06 part by weight of a surfactant F ⁴ T7 (manufactured by Dai Nippon Ink Chemical Industry Co., Ltd.), 0.72 part by weight of a photoinitiator Irgacurel 27 (manufactured by Ciba), and 50 parts by weight of a solvent Methyl Ethyl Ketone To prepare a coating composition. Manufacturing Example 2 Anti-magnetic 10

In Production Example 1, the kind and / The components of Preparation Examples 1 to 10 and their contents are summarized in Table 1 below. Production Examples 11 to 14

The coating composition was prepared by varying the kind and / or content of each component in Production Example 1.

The silica fine particles SI, S2, and S3 added at the time of production were obtained by using the laser light diffraction method (dynamic laser scattering, refractive index, viscosity, and dielectric constant of the solvent in which the inorganic fine particles were dispersed and the inorganic fine particles, , A particle diameter of cumulative 10% was dlO, a particle diameter of cumulative 50% was d50, and a particle diameter of cumulative 90% was d90, when the cumulative particle diameter distribution along the particle diameter was measured according to the device name: Malvern Zetasizer Nano-ZS90. (Hereinafter referred to as S1 (hereinafter referred to as " S1 ") solution in which silica fine particles S1 (dl0 = 17 nm, d50 = 22 nm, d90 = 28 nm, surface modified with methacrylate silane coupling agent) (Hereinafter referred to as S2 dispersion solution) in which silica fine particles S2 (dl0 = 29 nm, d50-1 nm, d90 = 74 nm, surface modified with acrylate silane coupling agent) are dispersed in MEK in an amount of 30 wt% (Hereinafter referred to as S2 dispersion solution) in which 40 wt% of silica particles S3 (dlO = 108nm, d50 = 119nm, d90 = 131nm and surface modified with an acrylate silane coupling agent) are dispersed in MEK.

The components and contents of Production Examples 11 to 14 are summarized in Table 2 below.

[Table 1]

[Table 2]

In the Tables 1 and 2, the modulus of elasticity of the first and second coating layers refers to a value measured according to ASTM D882 in a state where each coating layer is peeled from the supporting substrate, and the characteristics of each component are as follows:

TMPTA (trimethylolpropane triacrylate): Mw = 338 g / mol, acrylate group equivalent = 113 g / mol

PETA (pentaerythritol tetraacrylate): Mw = 352 g / mol, acrylate group equivalent = 88 g / mol

DPEPA (dipentaerythritol pentaacrylate): Mw = 525 g / mol, acrylate group Equivalent = 105 g / mol

TEGDA (triethyleneglycol diacrylate): Mw = 258 g / mol, acrylate group equivalent = 129 g / mol

TPGDA (tripropyleneglycol diacrylate): Mw = 300 g / mol, acrylate group equivalent = 150 g / mol

PU3400 (trifunctional urethane acrylate compound): Mw = 2,500 g / mol, acrylate group equivalent = 833 g / mol

TA-604AU (trifunctional urethane acrylate compound): Mw = 2,300 g / mol, acrylate group equivalent = 767 g / mol

MU9800 (9-functional urethane acrylate compound): Mw = 3,500 g / mol, acrylate group equivalent: 389 g / mol

MU9020 (10-functional urethane acrylate compound): Mw = 4,500 g / mol Acrylate group equivalent: 450 g / mol Production Example of Flexible Film

Example 1

The coating composition of Preparation Example 1 was applied on both sides of a polyimide support substrate (size: 20 cm x 20 cm, thickness: 50 ml) having an elastic modulus value of 6 GPa measured according to ASTM D882 by bar coating method, The first coating layer (thickness: 30) was formed by photocuring with a metal halide lamp having a wavelength of -320 nm.

A second coating layer (thickness: 30) was formed by applying the coating composition to the backside of the supporting substrate of the coating composition of Production Example 6 and photo-curing in the same manner to produce a flexible film. Examples 1 to 5

A flexible film was prepared in the same manner as in Example 1, except that the coating composition and / or thickness used for the second coating layer in Example 1 were different. Comparative Examples 1 to 26 The same procedure as in Example 1 was carried out except that the kind and / or thickness of the coating composition used in the first coating layer, the kind of the coating composition used in the second coating layer, and / or the thickness of the coating layer were changed in Example 1 To prepare a flexible film. The types of the coating compositions and the thicknesses of the coating layers of Examples 1 to 5 and Comparative Examples 1 to 42 are summarized in Tables 3 to 5, respectively.

[Table 3]

Comparative Example 9 Production Example 110 Production Example 520 Comparative Example 10 Preparation Example 1 10 Preparation Example 5 30 Comparative Example 11 Preparation Example 1 ^■ 10 Production Example 5 40 Comparative Example 12 Production Example 110 Production Example 550 Comparative Example 13 Preparation 1 10 Production Example 6 20 Comparative Example 14 Production Example 1 10 Production Example 6 30 30 Comparative Example 15 Production Example 1 10 Production Example 6 40 Comparative Example 16 10 Production Example 6 50

Production Example 1

Comparative Example 17 Production Example 1 30 Production Example 5 20 Comparative Example 18 Production Example 1 30 Production Example 5 30 Comparative Example 19 Production Example 1 30 Production Example 5 40 Comparative Example 20 Production Example 1 30 Production Example 5 50 Comparative Example 21 Production Example 1 30 Production Example 3 80 Comparative Example 22 Production Example 1 30 Production Example 5 80 Comparative Example 23 Production Example 1 30 Production Example 7 80 Comparative Example 24 Production Example 1 30 Production Example 8 80 Comparative Example 25 Production Example 1 30 Production Example 9 80 Comparative Example 26 Production Example 1 30 Production Example 10 80

[Table 5]

First Coating Layer Second Coating Layer Coating Composition Thickness Coating Composition Thickness

(Unit: urn) Comparative Example 27 Production Example 1 30 Production Example 11 30 Comparative Example 28 Production Example 1 30 Production Example 12 30 Comparative Example 29 Production Example 1 30 Production Example 13 30 Comparative Example 30 Production Example 1 30 Production Example 14 30 Comparative Example 31 Production Example 1 30 Production Example 11 80 Comparative Example 32 Production Example 1 30 Production Example 12 80

Comparative Example 33 Production Example 1 30 Production Example 13 80

Comparative Example 34 Production Example 1 30 Production Example 14 80

Comparative Example 35 Production Example 2 30 Production Example 11 30

Comparative Example 36 Production Example 2 30 Production Example 12 30

Comparative Example 37 Production Example 2 30 Production Example 13 30

Comparative Example 38 Production Example 2 30 Production Example 14 30

Comparative Example 39 Production Example 2 30 Production Example 11 80

Comparative Example 40 Production Example 2 30 Production Example 12 80

Comparative Example 41 Production Example 2 30 Production Example 13 80

Comparative Example 42 Production Example 2 30 Production Example 14 80

1) Pencil Hardness

Using a pencil hardness tester, the surface of the first coating layer was reciprocated once at a load of 750 g and at an angle of 45 degrees in accordance with the measurement standard JIS K5400-5-4, and the maximum hardness without a groove was confirmed.

2) Dynamic folding (DF) test

1 is a view schematically showing a method of performing a dynamic folding test on a film according to an embodiment of the present invention.

Each of the films of the examples and comparative examples was cut and laser cut to a size of 80 X 140 mm so as to minimize micro cracks at edge portions. The laser cut film was placed on the measuring equipment so that the second coating layer was directed to the bottom surface. The film was folded at 80 to 90 degrees with respect to the bottom surface at room temperature so that the gap was 5 mm. The folding speed was once per 1.5 seconds), and the maximum number of repetitions in which a crack of 3 cm or more occurred was measured.

If you do not crack more than 3cm by repeating 100,000 times, I did not go.

3) Curl test

The films of the examples and comparative examples were cut into a square of 10 cm x 10 cm, and the outer surface of the film curvature (dried surface) was placed on the bottom of the experimental table. The four corner points of the square were measured as a distance from the floor, Respectively. + Curl when the first coating layer is the inner surface of Curl, and Curl when the second coating layer is the inner surface of Curl. 4) Dent test

Fig _. 1 is a schematic view showing a method of performing a dent test on a film according to an embodiment of the present invention.

An adhesive layer (material: OCA, thickness and polyimide film (thickness: 50)) was laminated on each of the films of Examples and Comparative Examples on the second coating layer. The laminated film was laminated on the bottom I left it.

Starting from a load of 100 g using a 3H hard pencil, the surface of the first coating layer was reciprocated once at an angle of 45 degrees while adding a load of 100 g, and then the maximum weight without damages such as pressing marks was confirmed on all the layers. We checked up to 1500g and did not proceed if damage did not occur.

The physical property measurement results are shown in Tables 6 to 8 below.

[Table 6]

Comparative Example 1 9H 300g 0mm Comparative Example 2 9H 0.1k or less 1500g or more 0mm Comparative Example 3 8H 0.1k or less 300g 0mm Comparative Example 4 8H 0.1k or less 1500g or more 0mm Comparative Example 5H 100k or more Less than lOOg 0mm Comparative Example 6 H 100k or more Less than lOOg 0mm Comparative Example 7 F 100k or more Less than lOOg 0mm

O

Comparative Example 8 F 100k or more Less than lOOg 0mm Comparative Example 9 4H 100k or more 400g + 2mm Comparative Example 10 4H 100k or more 800g to 5mm Comparative Example 11 3H 100k or more 1200g to 10mm Comparative Example 12 3H 100k or more 1500g or more -15mm Comparative Example 13 3H 100k or more 800g + lmm Comparative Example 14 3H 100k or more 1200g -4mm Comparative Example 15 3H 100k or more 1500g or more -8mm Comparative Example 16 3H 100k or more 1500g or more -13mm Comparative Example 17 9H 40k 500g + 25mm Comparative Example 18 9H 60k lOOOg + 15mm Comparative Example 19 8H 50k 1500g or more + 8mm Comparative Example 20 8H 40k 1500g or more + 4mm Comparative Example 21 8H 20k 1500g or more -3mm Comparative Example 22 8H 30k 1500g or more -2mm Comparative Example 23 8H 70k 1500g or more -2mm Comparative Example 24 4H 100k More than 1500g + 6mm Comparative Example 25 7H 80k 1500g or more -1mm Comparative Example 26 3H 100k or more 1500g or more + 6mm [Table 8]

Referring to Tables 6 to 8, the film of the present invention exhibited good properties in all properties, and exhibited excellent flexibility and impact resistance particularly in dynamic folding test, dent test and curl test as well as high hardness of 7H or more. On the other hand, the films of the comparative examples did not exhibit a pencil hardness or exhibited flexibility and inner layer rigidity suitable for a flexible film.

Claims

Claims:

[Claim 1]

A support substrate;

A second crosslinked aerial member formed on the back surface of the supporting substrate and having at least one kind of a different 3 to 6 functional acrylate binder, a bifunctional acrylate binder, and a 2 to 4 functional urethane acrylate binder, And a second coating layer comprising a coalescent,

The elastic modulus of the second coating layer measured in accordance with ASTM D882 in the state where the second coating layer is peeled off from the supporting substrate is 400 to 650 MPa, the thickness of the first coating layer is 20 to 20, the thickness of the second coating layer is 20 to 150 [Lambda]

Wherein a ratio of a thickness of the first coating layer to a thickness of the second coating layer is 1: 1 to 1: 5.

[Claim 2]

The method of claim 1, wherein the bifunctional acrylate binder is selected from the group consisting of triethylene glycol diacrylate (TEGDA), tetraethylene glycol diacrylate (TTEGDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), polyethylene glycol diacrylate (PEGDA), ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), diethylene glycol diacrylate (DEGDA ), Butanediol diacrylate (BDDA) and nucleic acid diol diacrylate (HDDA).

[Claim 3]

The composition according to claim 1, wherein the content of the 3 to 6 functional acrylate-based binder Wherein the acrylate equivalent weight is 50 to 300 g / m 2.

Claim 4

The flexible film according to claim 1, wherein the equivalent weight of the one to four functional urethane acrylate binder is 100 to 10,000 g / m 2.

[Claim 5]

The flexible film according to claim 1, wherein the inorganic fine particles are silica fine particles, aluminum oxide particles, titanium oxide particles, zirconia oxide particles, or zinc oxide particles.

[Claim 6]

The flexible film according to claim 1, wherein the first coating layer comprises 40 to 80 parts by weight of the first crosslinking copolymer and 20 to 60 parts by weight of the inorganic fine particles. ,

7.

The method according to claim 1, wherein the second crosslinked copolymer comprises 20 to 80 parts by weight of the 3 to 6 functional acrylate binder, 10 to 40 parts by weight of the bifunctional acrylate binder, And 10 to 70 parts by weight of a urethane acrylate-based binder.

8.

The flexible film of claim 1, wherein the thickness of the first coating layer is from 20 to 60 / im and the thickness of the second coating layer is from 30 to 120. [

[Claim 9]

In the present invention, the singe-based support substrate may be made of polyimide (PI), polyimideamide, polyamide PA, Polyetheretherketone (PEEK), cyclic olefin polymer (COP), polyetheretherketone (PEEK), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyethylene naphthalate Wherein the flexible film is at least one selected from the group consisting of polyacrylate (PAC), polymethylmethacrylate (PMMA), and triacetylcellulose (TAC).

Claim 10

The flexible film according to claim 1, wherein the first coating layer exhibits a pencil hardness of 6H or more under a load of 750 g.

Claim 11

The method of claim 1, wherein the second coating layer, cracks (crack) does not occur when the flexible ^"film at room temperature so as to face the bar kkaljjok hayeoteul folded open and close 10 million times repeated for the create Tel (mandrel) having a diameter of 5mm , Flexible film.