KR102273689B1 - Optical laminate and display device - Google Patents

Abstract

The present invention includes a substrate and a hard coating layer formed on at least one surface of the substrate and including two or more kinds of inorganic particles having an average radius different from that of a binder resin, wherein the hard coating layer includes two or more first inorganic particles. An optical laminate and a display device including the optical laminate, wherein a domain formed by surrounding two or more second inorganic particles is formed, wherein the first inorganic particle and the second inorganic particle are different components from each other .

Description

Optical laminate and display device {OPTICAL LAMINATE AND DISPLAY DEVICE}

The present invention relates to an optical laminate and a display device.

Recently, with the development of mobile devices such as smartphones and tablet PCs, thinning and slimming of substrates for displays are required. Glass or tempered glass is generally used as a material having excellent mechanical properties for a window or a front panel for a display of such a mobile device. However, the glass causes the mobile device to become heavy due to its own weight, and there is a problem of breakage due to external impact.

Therefore, plastic resins are being researched as materials that can replace glass. Plastic resin film is suitable for the trend of pursuing lighter mobile devices because it is lightweight and less prone to breakage. In particular, in order to achieve a film having high hardness and abrasion resistance, a film in which a hard coating layer made of a plastic resin is coated on a supporting substrate has been proposed.

As a method of improving the surface hardness of the hard coat layer, a method of increasing the thickness of the hard coat layer may be considered. In order to secure enough surface hardness to replace glass, it is necessary to implement a certain thickness of the hard coating layer. However, as the thickness of the hard coating layer increases, the surface hardness may increase, but wrinkles or curls increase due to curing shrinkage of the hard coating layer, and at the same time, cracks or peeling of the hard coating layer are easy to occur. is not easy

Meanwhile, for aesthetic and functional reasons, a display in which a part of the display device is curved or flexible has been recently attracting attention, and this trend is particularly noticeable in mobile devices such as smart phones and tablet PCs. However, since glass is unsuitable for use as a cover plate to protect such a flexible display, it needs to be replaced with a plastic resin or the like. However, for this purpose, it is difficult to manufacture a film having sufficient flexibility while exhibiting glass-level high hardness.

The present invention exhibits high hardness while simultaneously satisfying the physical property balance of flexibility and high hardness, and in particular, there is little damage to the film even by repeated bending or folding operations, so bendable, flexible, rollable, or foldable mobile devices , or provides an optical laminate that can be easily applied to a display device.

In addition, the present invention provides a display device including the optical laminate

In this specification, the substrate; and a hard coating layer formed on at least one surface of the substrate and comprising two or more kinds of inorganic particles having an average radius different from that of the binder resin, wherein the hard coating layer includes two or more first inorganic particles and two or more second A domain formed by surrounding inorganic particles is formed, and the first inorganic particle and the second inorganic particle are different components from each other.

In addition, the present specification provides a display device including an optical laminate.

Hereinafter, an optical laminate and a display device according to specific embodiments of the present invention will be described in more detail.

As used herein, "flexible" means a state having a degree of flexibility that does not cause cracks with a length of 3 mm or more when wound on a cylindrical mandrel having a diameter of 4 mm, and thus, the present invention of flexible plastic film is applicable as a cover film of a bendable, flexible, rollable, or foldable display.

According to one embodiment of the invention, the substrate; and a hard coating layer formed on at least one surface of the substrate and comprising two or more kinds of inorganic particles having an average radius different from that of the binder resin, wherein the hard coating layer includes two or more first inorganic particles and two or more second An optical laminate may be provided, in which a domain formed by surrounding inorganic particles is formed, and the first inorganic particles and the second inorganic particles are different components from each other.

The present inventors conducted research on an optical laminate, a cover window, or a device substrate applicable to a display device having a thinner thickness, and added two or more first inorganic particles to the hard coating layer formed on a predetermined substrate. When a domain formed by surrounding two or more second inorganic particles is formed, and the first inorganic particle and the second inorganic particle are different components from each other, high hardness while simultaneously satisfying the balance of physical properties of flexibility and high hardness In particular, it was confirmed through experiments that the film can be easily applied to bendable, flexible, rollable, or foldable mobile devices or display devices because there is little damage to the film even by repeated bending or folding operations. was completed.

Since the optical laminate may have properties that can replace tempered glass, etc., it may not be broken by pressure or force applied from the outside, but also may have characteristics such that it can be sufficiently bent and folded.

Physical properties such as bending durability and surface hardness of the optical laminate may be implemented by optimizing the hard coating layer formed on the substrate. More specifically, the characteristics of the optical laminate may be due to the formation of the above-described domains.

The above-described domain formed in the hard coating layer has a high-density packing structure in which the first inorganic particles are surrounded by the first inorganic particles with the second inorganic particles, and accordingly, when only single particles are distributed, When compared, deformation and damage caused by external forces may have relatively few characteristics. For this reason, the hard coating layer may have a higher surface hardness, and with this, the optical laminate of the embodiment including the hard coating layer simultaneously satisfies the balance of properties of flexibility and high hardness, and repeats bending or folding operations. Also, damage to the internal structure can be prevented.

The second inorganic particle may have a larger average radius compared to the first inorganic particle, and more specifically, the domain includes two or more first inorganic particles having an average radius of 10 to 15 nm and an average radius of 20 to 35 nm. Two or more second inorganic particles may be formed to surround. In this case, the domain may have a high-density packing structure in which first inorganic particles having a relatively small average radius are surrounded by second inorganic particles having a relatively large average radius.

The “domain formed by enclosing two or more first inorganic particles having an average radius of 10 to 15 nm and two or more second inorganic particles having an average radius of 20 to 35 nm” is defined as the binder resin and It may be formed by adjusting the mixing process of the two or more kinds of inorganic particles having the different average radii, controlling the content of the components, or in particular controlling the drying rate of the forming process of the hard coating layer.

Accordingly, the thickness of the hard coating layer is not particularly limited, but the "two or more first inorganic particles having an average radius of 10 to 15 nm are surrounded by two or more second inorganic particles having an average radius of 20 to 35 nm. In order to make the "domain" to be formed more smoothly, the hard coating layer is preferably applied and dried to have a thickness of at least a certain level.

For example, the hard coating layer may have a thickness of 25 μm or more, or 30 μm to 100 μm, and as the hard coating layer has this thickness, the hard coating layer has an average radius of 10 to 15 nm. A domain formed by surrounding the inorganic particles with two or more second inorganic particles having an average radius of 20 to 35 nm may be formed. When the thickness of the hard coating layer is thin, for example, 20 μm or less, depending on the drying conditions, the coating solution forming the hard coating layer is dried in a relatively short time, so that the viscosity of the coating layer increases rapidly and the above-mentioned domains are not formed. may not be

Whether or not the "domain formed by enclosing two or more first inorganic particles having an average radius of 10 to 15 nm and two or more second inorganic particles having an average radius of 20 to 35 nm" is formed is determined by SEM (scanning electron microscope), etc. It can be confirmed by using an apparatus, and by measuring the distance between the two or more second inorganic particles having an average radius of 20 to 35 nm through small-angle X-ray scattering analysis, it is possible to indirectly confirm whether the domain is formed.

For example, the inorganic particles included in the hard coating layer include first inorganic particles having an average radius of 10 to 15 nm and second inorganic particles having an average radius of 20 to 35 nm, and the hard coating layer has an average radius of 10 to 15 nm. As a domain is formed by surrounding two or more first inorganic particles having an average radius of two or more second inorganic particles having an average radius of 20 to 35 nm, the first inorganic particles located at the center of the domain are placed opposite each other The distance (Rd) between the centers of the two second inorganic particles positioned to be in the same manner may be 60 nm to 100 nm.

The distance (Rd) between the centers of the second inorganic particles among the domains of the inorganic particles can be measured and calculated through small-angle X-ray scattering analysis of the radiation accelerator, for example, u of the (Pohang) Radiation Accelerator Research Institute (Pohang Light Source). -SAXS beam-line 9A is used, the measured data set is merged by the NIST SANS data reduction package, and data analysis (result optimization (fitting)) can be performed using the model function included in the NIST SANS package. .

As described above, the hard coating or the like includes two or more kinds of inorganic particles having an average radius different from that of the binder resin, and the two or more kinds of inorganic particles include a first inorganic particle having an average radius of 10 to 15 nm and 20 to 35 nm. It may include a second inorganic particle having an average radius of. The first inorganic particles may have an average radius of 10 to 15 nm, or 11 to 14 nm, or 12 to 13 nm, and the second inorganic particles may have an average radius of 20 to 35 nm, or 21 to 30 nm, or 22 to 26 nm. can have

As the inorganic particles included in the hard coating layer include the first inorganic particles having an average radius of 10 to 15 nm and the second inorganic particles having an average radius of 20 to 35 nm, the hard coating layer has the above-described domains more easily can be created

More specifically, the ratio of the average radius of the first inorganic particles having an average radius of 10 to 15 nm to the average radius of the second inorganic particles having an average radius of 20 to 35 nm is 1:1.2 or more, or 1:1.5 or more, or 1:2 It may be greater than or equal to 1:20 or less. When the ratio of the average radius of the second inorganic particle to the first inorganic particle is too small, the sizes of the two types of particles become similar and a domain having a high-density particle packing may not be formed. When the ratio of the average radius of the second inorganic particle to the first inorganic particle is too large, the size of the above-described domain increases, and thus the haze of the hard coating layer may be greatly increased.

The average radius of each of the first inorganic particle and the second inorganic particle can be confirmed through a commonly known method, for example, the radius of the individual particle identified in the electron micrograph (SEM, TEM, etc.) of the hard coating layer is measured to be calculated and derived, or it may be an average radius of inorganic particles calculated through an X-ray scattering experiment.

Meanwhile, the first inorganic particles may have an average radius of 10 to 15 nm, and in this case, the radius of the individual inorganic particles capable of forming domains among the individual inorganic particles included in the first inorganic particles is ±5 nm of the average radius. is the range of For example, the radius of the individual inorganic particles included in the first inorganic particle and forming the domain may be included in the range of 5 to 20 nm.

In addition, the second inorganic particles may have an average radius of 20 to 35 nm, and in this case, the radius of the individual inorganic particles capable of forming domains among the individual inorganic particles included in the second inorganic particles is ±5 nm of the average radius. is the range of For example, the radius of the individual inorganic particles included in the second inorganic particle and forming the domain may be included in the range of 15 to 40 nm.

The two or more kinds of inorganic particles having different average radii may be, for example, metal atoms such as silica, aluminum, titanium, zinc, or oxides and nitrides thereof, and each independently silica particles, aluminum oxide particles, titanium oxide particles, Alternatively, zinc oxide particles and the like may be used.

Meanwhile, as described above, the first inorganic particle and the second inorganic particle forming the domain may be different components from each other. When the first and second inorganic particles forming the domain are different components from each other, compatibility between the particles is higher, so that the domain can be uniformly dispersed over the entire area of the hard coat layer at all times.

Since the first inorganic particle and the second inorganic particle are different components from each other, the first inorganic particle and the second inorganic particle may be different metal particles, or oxides and carbides containing different metals (for example, ZrC), hydroxide (eg Fe(OH)3, Mg(OH)2, Ni(OH)2), peroxide hydroxide (eg FeOOH), or nitride.

As a more specific example of the first inorganic particle and the second inorganic particle, the first inorganic particle may be silica, and the second inorganic particle may be zirconia or titania.

On the other hand, as described above, the hard coating layer may exhibit a pencil hardness of 5H or more, or 6H or more, or 7H or more under a load of 750 g.

As described above, although flexibility can be secured in a film or an optical laminate having a thin thickness, it is not easy to secure durability against repeated bending or folding operations while ensuring high surface strength.

On the other hand, the hard coating layer included in the optical laminate of the embodiment may have the above-described surface hardness, with a gap of 5 mm in the middle of the optical laminate with both sides of the optical laminate on the bottom surface When folded and unfolded at 90 degrees, it is repeated 100,000 times at room temperature, and cracks do not occur.

5 is a diagram schematically illustrating a method for measuring bending durability properties for a flexible plastic film according to an embodiment of the present invention.

Referring to FIG. 5, after placing the film so that it is level with the floor, the interval between the folds in the middle of the film is 5 mm, and both sides of the film are folded and unfolded at 90 degrees with respect to the bottom surface about 1 to about 3 times / Durability against bending can be measured by repeating 100,000 times at room temperature at a speed of seconds (sec).

At this time, in order to keep the gap between the folds constant, for example, place the film so that it touches a rod with a diameter (R) of 5 mm, fix the rest of the film, and repeat folding and unfolding both sides of the film around the rod. method can be taken. In addition, the folded portion is not particularly limited as long as it is inside the film, and for convenience of measurement, the central portion of the film may be folded so that both sides of the film are symmetrical except for the folded portion.

In the measurement of durability, cracks of 1 cm or more or 3 mm or more do not occur, and cracks do not occur in the optical laminate of the embodiment even after bending 100,000 times.

On the other hand, the content of two or more different inorganic particles within the range in which domains are formed in the hard coating layer is not particularly limited, but preferably, the hard coating layer contains the first inorganic particles and the second inorganic particles based on 100 weight of the binder resin. It may include a total of 20 to 80 parts by weight of the particles.

When the content of two or more different types of inorganic particles included in the hard coating layer is too small, it may be difficult to form the domain or the hardness of the hard coating layer may be low. In addition, when the content of two or more different types of inorganic particles included in the hard coating layer is too high, hardness may be increased, but flexibility of the optical laminate may be greatly reduced or durability against repeated bending or folding operations may also be reduced.

The hard coating layer may include a binder resin.

Specific examples of the binder resin are not limited, for example, may be a polymer or copolymer of monomer(s) having a photocurable reactive group, specifically (meth)acrylate-based monomers or oligomers, vinyl-based monomers or oligomers, etc. It may be a polymer or copolymer formed from

For example, the binder resin may include a polymer or copolymer of 3 to 6 functional (meth)acrylate-based monomers.

The 3 to 6 functional acrylate-based monomer or oligomer is trimethylolpropane triacrylate (TMPTA), trimethylolpropaneethoxy triacrylate (TMPEOTA), glycerin propoxylated triacrylate (GPTA), pentaerythritol tetra acrylate (PETA) or dipentaerythritol hexaacrylate (DPHA). The 3 to 6 functional acrylate-based monomers or oligomers may be used alone or in combination of different types.

The (meth) acrylate-based monomer or oligomer or vinyl-based monomer or oligomer 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, or about 200 to about 500 g /mol.

The 3 to 6 functional acrylate-based binder has an acrylate equivalent weight in the range of about 50 to about 300 g/mol, or about 50 to about 200 g/mol, or about 50 to about 150 g/mol. can

When the weight average molecular weight and the acrylate equivalent of the 3- to 6-functional acrylate-based binder are within the above-described ranges, a coating layer with more optimized physical properties may be formed.

On the other hand, as the substrate, various supporting substrates known to be applicable to optical films or optical devices may be used without significant limitation.

For example, the substrate has an elastic modulus of about 4 GPa or more when measured according to ASTM D882 so that the optical laminate can secure flexibility and hardness, and has an optical thickness in the range of 20 to 300 μm As a transparent plastic resin for use, it can be used without special restrictions on the manufacturing method or material of the supporting substrate such as a stretched film or a non-stretched film.

Among the conditions described above, the elastic modulus may be about 4 GPa or more, or about 5 GPa or more, or about 5.5 GPa or more, or about 6 GPa or more, and the upper limit may be about 9 GPa or less, or about 8 GPa or less, or about 7 GPa or less. have. If the elastic modulus is less than 4 GPa, sufficient hardness may not be achieved, and if it is too high, exceeding 9 GPa, it may be difficult to form a flexible film.

In addition, the thickness of the supporting substrate may be about 20 μm or more, or about 25 μm or more, or about 30 μm or more, and the upper limit thereof is about 300 μm or less, or about 200 μm or less, or about 150 μm or less, or about 100 μm or less. If the thickness of the substrate is less than 20 μm, there is a risk of fracture or curling during the coating layer forming process, and it may be difficult to achieve high hardness. On the other hand, if the thickness exceeds 300㎛, the flexibility may be low, it may be difficult to form a flexible film.

As the substrate, it satisfies the above-described elastic modulus and thickness range, for example, polyimide (PI), polyimideamide (polyimideamide), polyetherimide (PEI), polyethyleneterephthalate (polyethyleneterephtalate, PET), polyethylenenaphthalate (PEN), polyetheretherketone (PEEK), cyclic olefin polymer (COP), polyacrylate (PAC), polymethylmethacrylate , PMMA), or may be a film containing triacetylcellulose (TAC). The supporting substrate may be a single layer or a multilayer structure including two or more substrates made of the same or different materials as necessary, and is not particularly limited.

On the other hand, in the optical laminate of the embodiment, the above-described two or more first inorganic particles having an average radius of 10 to 15 nm are surrounded by two or more second inorganic particles having an average radius of 20 to 35 nm. A coating layer may be formed on one surface of the substrate, and a second hard coating layer containing a binder resin including a polymer or copolymer of a (meth)acrylate-based monomer may be formed on the other surface of the substrate.

By forming the second hard coating layer together with the above-described hard coating layer, the balance of properties of flexibility and high hardness of the optical laminate can be further improved, and durability and dent resistance against repeated bending or folding operations (Dent Resistance) ) can also be improved.

The thickness of each of the hard coating layer and the second hard coating layer having a domain formed by surrounding the two or more first inorganic particles having an average radius of 10 to 15 nm and two or more second inorganic particles having an average radius of 20 to 35 nm Although not particularly limited, when the combined thickness of the hard coating layer and the second hard coating layer is excessively increased, the flexibility of the optical laminate or durability against repeated bending or folding operations may be deteriorated. Accordingly, each of the hard coating layer and the second hard coating layer preferably has a thickness of 30 μm to 100 μm.

On the other hand, the optical laminate may be provided by applying and photocuring a coating composition including the above-described components on at least one surface of the substrate. The method of applying the coating composition is not particularly limited as long as it can be used in the technical field to which the present technology belongs, for example, bar coating method, knife coating method, roll coating method, blade coating method, die coating method, micro gravure coating method, comma coating method, slot die coating method, lip coating method, solution casting method, etc. can be used.

In the optical laminate, a plastic resin film, an adhesive film, a release film, a conductive film, a conductive layer, a liquid crystal layer, a coating layer, a cured resin layer, a non-conductive film, a metal mesh layer, or It may further include one or more layers, films, or films, such as a patterned metal layer.

For example, a conductive antistatic layer is first formed on a substrate and then a coating layer is formed thereon to give an anti-static function, or a low refractive index layer is introduced on the coating layer to provide a low reflection function. can also be implemented.

In addition, 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 lamination, coating, vapor deposition, sputtering, etc., of a freestanding film using an adhesive or adhesive film, but the present invention It is not limited thereto.

On the other hand, the hard coating layer, in addition to the binder resin, inorganic fine particles, etc., a photoinitiator, an organic solvent, a surfactant, a UV absorber, a UV stabilizer, an anti-yellowing agent, a leveling agent, an antifouling agent, a dye for improving color value, etc. It may further include components commonly used in the field. In addition, the content can be variously adjusted within a range that does not degrade the physical properties of the hard coating layer, so it is not particularly limited, but for example, it may be included in an amount of about 0.01 to about 30 parts by weight based on 100 parts by weight of the hard coating layer.

The surfactant may be a fluorine-based acrylate, a fluorine-based surfactant, or a silicone-based surfactant having 1-2 functional properties. In this case, the surfactant may be included in a dispersed or cross-linked form in the hard coating layer.

In addition, the additive may include a UV absorber or a UV stabilizer, and the UV absorber may include a benzophenone-based compound, a benzotriazole-based compound, or a triazine-based compound, and the UV stabilizer includes tetramethyl p and peridine (tetramethyl piperidine).

The photoinitiators include 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy). )phenyl]-2-methyl-1-propanone, methylbenzoylformate, α,α-dimethoxy-α-phenylacetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-) Morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone diphenyl (2,4, 6-trimethylbenzoyl)-phosphine oxide, or bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and the like, but are not limited thereto. In addition, 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, Esacure KIP 100F, and the like. These photoinitiators may be used alone or in combination of two or more different types.

Examples of the organic solvent include an alcohol-based solvent such as methanol, ethanol, isopropyl alcohol, and butanol, an alkoxy alcohol solvent such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol, acetone, and methyl Ketone solvents such as ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, and cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, Ether solvents such as diethylene glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, diethyl glycol monobutyl ether, diethylene glycol-2-ethylhexyl ether, benzene, toluene, xylene and The same aromatic solvents may be used alone or in combination.

On the other hand, the optical laminate of the embodiment may have a light transmittance of 88.0% or more, or 90.0% or more, and a haze of 1.5% or less, or 1.0% or less, or 0.5% or less.

Meanwhile, according to another embodiment of the present invention, a display device including the optical laminate of the embodiment may be provided.

The display device is not only a flat shape, but also a curved, bendable, flexible, rollable, or foldable type of mobile communication terminal, smart phone, or tablet PC. It includes both a touch panel and various displays.

An example of the display device may be a flexible light emitting device display device. The light emitting device display device may use the polymer film of the embodiment as a substrate, an external protective film, or a cover window. Specifically, the light emitting device display device may be an organic light emitting diode (OLED) display using the polymer film of the embodiment as a cover window. Except for using the polymer film as a cover window, a device part known as a component of a typical organic light emitting diode (OLED) display may be included.

For example, in the organic light emitting diode (OLED) display, a cover window including a polymer film may be positioned at an outer portion in a direction in which light or a screen is emitted, and a cathode providing electrons, an electron transport layer (Eletron Transport) Layer, an emission layer, a hole transport layer, and an anode providing holes may be sequentially formed.

In addition, the organic light emitting diode (OLED) display may further include a hole injection layer (HIL) and an electron injection layer (EIL).

In order for the organic light emitting diode (OLED) display to function and operate as a flexible display, in addition to using the polymer film as a cover window, the cathode and anode electrodes and each component are made of a material having a predetermined elasticity. Can be used.

As an example of the display device, there may be a rollable display or foldable display including the optical laminate of the embodiment.

The optical laminate may be used as a substrate, an external protective film, or a cover window in a rollable display device. The polymer film may not be broken by pressure or force applied from the outside, but may have elasticity or flexibility enough to be bent and folded.

The rollable display device may include the polymer film of the embodiment together with the light emitting element and the module on which the light emitting element is located, and the light emitting element and the module may also have elasticity or flexibility to the extent that it can be sufficiently bent and folded. have.

The rollable display device may have various structures depending on the field of application and specific form, for example, a structure including a cover plastic window, a touch panel, a polarizing plate, a barrier film, a light emitting device (OLED device, etc.), a transparent substrate, etc. can be

According to the present invention, high hardness is realized while simultaneously satisfying the balance of properties of flexibility and high hardness, and in particular, there is little damage to the film even by repeated bending or folding operations, so bendable, flexible, rollable, or foldable mobile An optical laminate that can be easily applied to a device or a display device, and a display device including the optical laminate may be provided.

Since the optical laminate may have physical properties that can replace tempered glass, etc., it may not only not be broken by external pressure or force, but may also have sufficient bending and folding characteristics, flexibility, It exhibits flexibility, high hardness, scratch resistance, and high transparency, and is bendable, flexible, rollable, or foldable because there is little damage to the film even under repeated or continuous bending or folding for a long time. It can be usefully applied to a mobile device, a display device, the front panel of various instrument panels, and a display unit.

1 schematically shows a cross-section of a domain formed in a hard coating layer included in an optical laminate according to an embodiment.
2 shows the results of small-angle X-ray scattering measurement for the hard coating layer of Example 1 using two types of inorganic particles and the results of fitting the results (black lines).
3 shows the results of small-angle X-ray scattering measurements for the hard coating layer using one type of inorganic particles (diameter 13 nm) and the results of fitting the results (black lines).
4 shows the results of small-angle X-ray scattering measurements for the hard coating layer using one type of inorganic particles (diameter 25 nm) and the results of fitting the results (black lines).
5 is a diagram schematically illustrating a method of performing a bending durability test on a film according to an embodiment of the present invention.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

[Preparation Example: Preparation of a coating solution for forming a hard coating layer]

A coating solution for forming a hard coating layer was prepared by mixing the components shown in Tables 1 and 2 below. (In Tables 1 and 2 below, R means the average radius of the inorganic particles calculated through the X-ray scattering experiment)

(Unit: g) Preparation Example 1 Preparation 2 Preparation 3 Preparation 4 Preparation 5 Preparation 6 bookbinder
for formation
monomer TMPTA 10 10 10 10 10 10 PETA 20 20 20 20 20 20 DPEPA 20 20 20 20 20 20 TPGDA 5 5 5 5 5 5 TA-604AU 5 5 5 5 5 5 weapon
particle SiO ₂ (R = 25 nm) 20 20 SiO ₂ (R = 13 nm) 20 20 TiO ₂ (R = 24 nm) 20 20 TiO ₂ (R = 12 nm) 20 20 ZrO ₂ (R = 27 nm) 20 20 ZrO ₂ (R = 11 nm) 20 20 leveling agent 0.06 0.06 0.06 0.06 0.06 0.06 photoinitiator 0.72 0.72 0.72 0.72 0.72 0.72 Organic solvent (Methyl Ethyl Ketone) 50 50 50 50 50 50

(Unit: g) Preparation 7 Preparation 8 Preparation 9 Preparation 10 Preparation 11 Preparation 12 Preparation 13 bookbinder
for formation
monomer TMPTA 10 10 10 10 10 10 10 PETA 20 20 20 20 20 20 10 DPEPA 20 20 20 20 20 20 10 TPGDA 5 5 5 5 5 5 20 TA-604AU 5 5 5 5 5 5 50 weapon
particle SiO ₂ (R = 25 nm) 40 SiO ₂ (R = 13 nm) 40 TiO ₂ (R = 24 nm) 40 TiO ₂ (R = 12 nm) 40 ZrO ₂ (R = 27 nm) 40 ZrO ₂ (R = 11 nm) 40 leveling agent 0.06 0.06 0.06 0.06 0.06 0.06 0.1 photoinitiator 0.72 0.72 0.72 0.72 0.72 0.72 1.21 organic solvent
(Methyl Ethyl Ketone) 50 50 50 50 50 50 30

ingredient Chemical name/product name manufacturer molecule
Amount (g/mol) Acrylate count Acrylate equivalent TMPTA Trimethylolpropane Triacrylate 338 3 113 PETA Pentaerythritol Tetraacryl 352 4 88 DPEPA Dipentaerythritol Pentaacrylate 525 5 105 TPGDA Tripropyleneglycol Diacrylate 300 2 150 TA-604AU Ilyu Co., Ltd. 2300 3 767 leveling agent F477 DIC Corporation photoinitiator Irgacure 127 Ciba Specialty Chemicals

[Examples and Comparative Examples: Preparation of optical laminates]

Each of the coating compositions described in the following table was applied to a polyimide substrate (size: 20 cmｘ30 cm, thickness: 35 μm) having an elastic modulus value of 6.0 GPa measured according to ASTM D882 by a bar or slot coating method, and air atmosphere at 80 degrees for 3 minutes dried under An optical laminate was prepared by photocuring with a metal halide lamp (light quantity: 200mJ/cm ^{2 ) having a wavelength of 290 to 320 nm.} The photocuring was carried out in a nitrogen or argon atmosphere, and the light irradiation time was 30 seconds.

<Experimental Example: Measurement of physical properties of optical laminates>

Experimental Example 1: Domain confirmation of inorganic particles and measurement of distance (Rd) between centers of two second inorganic particles among domains

(1) Intensity vs. obtained by small-angle X-ray scattering method. By fitting the wavevector (q) curve using the model function included in the NIST SANS package, it was determined whether the domain of inorganic particles was formed in Hard 1 (front) of each optical laminate in Examples and Comparative Examples. was confirmed, and the distance (Rd) between the centers of the two second inorganic particles among the domains of the inorganic particles was obtained.

Fig. 2 shows the results of small-angle X-ray scattering measurements for the hard coating layer of Example 1 using two types of inorganic particles, and the results of optimizing the results (black lines), and Figs. 3 and 4 show 1, respectively. Small-angle X-ray scattering measurement results for the hard coating layer using inorganic particles (diameter 13 nm and diameter 25 nm) and the results of fitting the results (black lines) are shown.

1) device

u-SAXS beam-line 9A from the radiation accelerator (Pohang Light Source)

<Measurement conditions>

E = 11.1 KeV, 19.9 keV,

E/E = 2*10^-4

E/E = 2*10 ^-4

q range used: 0.0024 = q (Å ^-1 ) = 0.5

Sample to detector distance (SDD; 6.5 m (11.1 keV), 2.5 m (19.9 keV))

pin holes collimated

2D CCD Detector (Rayonix SX165, USA)

2) How to measure

-Film-type samples are attached to the sample holder using transparent tape.

-The 2D image obtained in the experiment is circularly averaged based on the beam stop and converted into a 1D image (the intensity value of the experimental data is not changed to an absolute value, so the unit is arbitrary unit, a.u.).

The two data sets per sample measured with an SDD of 6.5 m at an energy of -11.1 KeV and an SDD of 2.5 m at an energy of 19.9 keV are merged by the NIST SANS data reduction package, and data analysis is performed in the NIST SANS package. The included model function was used.

Experimental Example 2: Pencil hardness

For the hard coating layer formed on the front surface of each optical laminate in Examples and Comparative Examples, a scratch of 750 g according to the measurement standard JIS K5400-5-4 using a pencil hardness tester, after reciprocating three times at an angle of 45 degrees The maximum hardness was confirmed.

Experimental Example 3: Dent Resistance Measurement

In each of the optical laminates of Examples and Comparative Examples, an adhesive layer (material: OCA, thickness of 25 µm) and a polyimide film (thickness of 50 µm) were laminated on Hard 2 (back). This laminated film was placed on the floor with Hard 1 (front) facing upwards.

Using a 3H hardness pencil, starting with a load of 100 g and adding 100 g each, the surface of the first coating layer was moved once at an angle of 45 degrees, and the maximum weight was confirmed without damage such as press marks on all layers. Checked up to 1500 g and if no damage occurred, no further progress was made.

Experimental Example 4: Bending durability test

5 is a diagram schematically illustrating a method of performing a bending durability test on a film according to an embodiment of the present invention.

Examples and Comparative Examples, but cut with respect to each optical laminate, laser cutting to a size of 80 x 140mm to minimize microcracks in the edge (edge) portion. Lay the laser-cut film on the measuring device and make the gap between the folds 5 mm. At room temperature, both sides of the film are folded and unfolded at 90 degrees with respect to the bottom surface (the film folding speed is once every 1.5 seconds) was repeated 10,000 times.

After the film was peeled off after repeating 10,000 times, it was observed whether cracks with a length of 3 mm or more occurred (OK, NG). When cracks did not occur, bending was repeated 10,000 times and observing whether cracks occurred, and the maximum number of repetitions without cracks was measured. If cracks did not occur until repeated 100,000 times, it was judged that the bending durability was good.

The measurement results of the physical properties are shown in Tables 4 to 5 below.

Hard 1 (front) Hard 2 (the back) face
pencil hardness Dent
generated load Folding 100,000 times Domain of inorganic particles
Formation Rd
(nm) Furtherance thickness
(um) Furtherance thickness
(um) Example 1 Preparation Example 1 40 Preparation 13 70 7H 1500g OK ○ about 70-90 Example 2 Preparation 2 40 Preparation 13 70 7H 1500g OK ○ Approx. 79-90 Example 3 Preparation 3 40 Preparation 13 70 7H 1500g OK ○ About 60-85 Example 4 Preparation 4 40 Preparation 13 70 7H 1500g OK ○ About 60-85 Example 5 Preparation 5 40 Preparation 13 70 7H 1500g OK ○ about 70-100 Example 6 Preparation 6 40 Preparation 13 70 7H 1500g OK ○ about 70-100 Example 7 Preparation Example 1 30 Preparation 13 70 5H 1300g OK ○ about 70-90 Example 8 Preparation 2 30 Preparation 13 70 5H 1300g OK ○ Approx. 79-90 Example 9 Preparation 3 30 Preparation 13 70 5H 1300g OK ○ About 60-85 Example 10 Preparation 4 30 Preparation 13 70 5H 1300g OK ○ About 60-85 Example 11 Preparation 5 30 Preparation 13 70 5H 1300g OK ○ about 70-100 Example 12 Preparation 6 30 Preparation 13 70 5H 1300g OK ○ about 70-100

Hard 1 (front) Hard 2 (the back) face
pencil hardness Dent
generated load Folding 100,000 times Domain of inorganic particles
Formation Rd
(nm) Furtherance thickness
(um) Furtherance thickness
(um) Comparative Example 1 Preparation 7 40 Preparation 13 70 4H 1200g OK X - Comparative Example 2 Preparation 8 40 Preparation 13 70 4H 1200g OK X - Comparative Example 3 Preparation 9 40 Preparation 13 70 4H 1200g OK X - Comparative Example 4 Preparation 10 40 Preparation 13 70 4H 1200g OK X - Comparative Example 5 Preparation 11 40 Preparation 13 70 4H 1200g OK X - Comparative Example 6 Preparation 12 40 Preparation 13 70 4H 1200g OK X - Comparative Example 7 Preparation 7 30 Preparation 13 70 3H 1000g OK X - Comparative Example 8 Preparation 8 30 Preparation 13 70 3H 1000g OK X - Comparative Example 9 Preparation 9 30 Preparation 13 70 3H 1000g OK X - Comparative Example 10 Preparation 10 30 Preparation 13 70 3H 1000g OK X - Comparative Example 11 Preparation 11 30 Preparation 13 70 3H 1000g OK X - Comparative Example 12 Preparation 12 30 Preparation 13 70 3H 1000g OK X -

As shown in Tables 4 to 5, in the hard coating layer formed on the front surface of the optical laminate of the examples, "two or more first inorganic particles having an average radius of 10 to 15 nm are added to the second or more agents having an average radius of 20 to 35 nm. It is confirmed that a "domain formed by surrounding two inorganic particles" is formed (in this case, the first inorganic particle and the second inorganic particle are different components from each other), and as such, the optical laminates of the embodiment have a high surface hardness of 5H or higher. It was confirmed in a bending test that it has excellent durability and high dent resistance.

On the contrary, in the optical laminates of Comparative Examples including a hard coating layer prepared using one type of inorganic particles, domains of inorganic particles were not formed, and it was confirmed that relatively low surface hardness and dent resistance appeared.

In addition, it was confirmed that the optical laminates of Comparative Examples including a hard coating layer in which domains of inorganic particles were not formed even though two kinds of inorganic particles were used also exhibit relatively low surface hardness and dent resistance.

Claims (14)

materials; and
a hard coating layer formed on at least one surface of the substrate and comprising two or more kinds of inorganic particles having an average radius different from that of the binder resin;
A domain formed by surrounding two or more first inorganic particles and two or more second inorganic particles is formed in the hard coating layer,
The first inorganic particles and the second inorganic particles are different components from each other,
The distance (Rd) between the centers of the two second inorganic particles facing each other with the first inorganic particles positioned at the center in the domain is 60 nm to 100 nm, the optical laminate.
According to claim 1,
An optical laminate, wherein the second inorganic particles have a larger average radius than the first inorganic particles.
According to claim 1,
The domain is formed by surrounding two or more first inorganic particles having an average radius of 10 to 15 nm and two or more second inorganic particles having an average radius of 20 to 35 nm,
optical laminate.
delete According to claim 1,
The first inorganic particle and the second inorganic particle are metal particles different from each other or oxides, carbides, hydroxides, peroxides, or nitrides containing different metals.
According to claim 1,
The hard coating layer exhibits a pencil hardness of 5H or more under a load of 750 g, an optical laminate.
According to claim 1,
The hard coating layer has a thickness of 25 μm or more, an optical laminate.
According to claim 1,
The hard coating layer comprises a total of 20 to 80 parts by weight of the first inorganic particle and the second inorganic particle based on 100 weight of the binder resin, the optical laminate.
According to claim 1,
The binder resin is an optical laminate comprising a polymer or copolymer of 3 to 6 functional (meth) acrylate-based monomers.
According to claim 1,
The hard coating layer is formed on one surface of the substrate,
On the other side of the substrate, a second hard coating layer containing a binder resin including a polymer or copolymer of a (meth)acrylate-based monomer is formed, an optical laminate.
11. The method of claim 10,
The second hard coating layer has a thickness of 30 μm to 100 μm, an optical laminate.
According to claim 1,
wherein the substrate has a thickness of 20 μm to 300 μm.
According to claim 1,
The optical laminate is used as a cover window or an element substrate of a flexible display device.
A display device comprising the optical laminate of claim 1 .

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