KR102249775B1 - Patterned Hard Coating Film - Google Patents

Abstract

The present invention is a transparent substrate; And a hard coating film for a flexible display including a hard coating layer formed on one or both sides of the transparent substrate and partially or entirely patterned, and a flexible display provided with the hard coating film. The hard coating film according to the present invention has excellent flexibility because it can disperse the stress applied during bending, including the patterned hard coating layer.

Description

Patterned Hard Coating Film {Patterned Hard Coating Film}

The present invention relates to a patterned hard coating film, and more particularly, to a patterned hard coating film having excellent hardness and flexibility, and a flexible display having the same.

The hard coating film is used for the purpose of surface protection in image display devices such as a liquid crystal display device, an electroluminescent (EL) display device, a plasma display (PD), and a field emission display (FED).

Recently, flexible displays that can maintain display performance even if they bend like paper by using flexible materials such as plastics instead of glass substrates that are not flexible are rapidly emerging as next-generation display devices, and have high hardness. There is a demand for a hard coating film that not only has good scratch resistance, but also does not cause a curl phenomenon at the edge of the film during the manufacturing process or use, has adequate flexibility, and does not cause cracks.

In Korean Patent Application Publication No. 1999-0072670, a buffer layer having a thickness of 3 to 50 µm is installed on at least one side of the plastic base film to buffer the deformation of the hard coating layer due to the deformation of the plastic base film. A hard coating film formed by forming a hard coating layer of 3 to 15 μm is disclosed, and such a hard coating film is described as preventing cracking or peeling of the hard coating layer and having excellent pencil hardness.

However, such a hard coating film lacks flexibility and thus has a limit to be applied to a flexible display.

Republic of Korea Patent Publication No. 1999-0072670

The present invention is to solve the above problems, and one object of the present invention is to provide a hard coating film for a flexible display having excellent hardness and flexibility.

Another object of the present invention is to provide a flexible display provided with the hard coating film.

On the one hand, the present invention is a transparent substrate; And a hard coating layer formed on one or both sides of the transparent substrate and partially or entirely patterned.

In one embodiment of the present invention, the hard coating film may further include an adhesive layer or a buffer layer on the hard coating layer.

In one embodiment of the present invention, the hard coating film may further include an antireflection layer or a hard coating layer on the adhesive layer or the buffer layer.

On the other hand, the present invention provides a flexible display provided with the hard coating film.

The hard coating film according to the present invention includes a patterned hard coating layer and has flexibility because it can disperse stress applied during bending, and thus can be effectively used for flexible displays.

1 to 2 are views showing embodiments of a hard coating film according to the present invention.

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

One embodiment of the present invention is a transparent substrate; And a hard coating layer formed on one or both sides of the transparent substrate and partially or entirely patterned.

In one embodiment of the present invention, the patterned hard coating layer may have two or more patterned regions having different hardnesses.

1 to 2 are views showing embodiments of a hard coating film according to the present invention.

Referring to FIG. 1, the hard coating film according to an embodiment of the present invention alternately includes a rod-shaped first pattern area 11 and a second pattern area 12, and A hard coating layer 10 having a hardness greater than that of the second pattern region 12 is formed.

The widths of the first pattern area and the second pattern area may be the same or different, and specifically, may be 5 to 100 μm.

Referring to FIG. 2, the hard coating film according to an embodiment of the present invention forms a matrix form including a rectangular first pattern area 13 and a second pattern area 14 alternating vertically and horizontally, and the first pattern The hard coating layer 10 is formed in which the hardness of the region 13 is greater than that of the second pattern region 14.

The top, bottom, left and right widths of the first pattern area and the second pattern area may be the same or different, and specifically, may be 5 to 100 μm.

The hard coating layer according to an exemplary embodiment of the present invention includes a third pattern region that is greater than the hardness of the first pattern region, and the first pattern region, the second pattern region, and the third pattern region may be alternately positioned.

In one embodiment of the present invention, the hard coating layer is patterned as a whole, or partially, that is, only a portion that is folded or bent is patterned, so that stress applied during bending can be dispersed.

In one embodiment of the present invention, the patterned hard coating layer is patterning known in the art, such as a mask process, a lift-off process, etc. using two or more hard coating compositions forming coating layers of different hardness. It can be formed by a process. For example, a hard hard coating composition forming a hard hard coating layer on a transparent substrate is applied through a mask to form a first pattern area, and then a flexible hard coating composition is applied to move the mask and form a soft hard coating layer. A second pattern area may be formed.

The hardness of the hard coating layer can be adjusted by appropriately changing the type or composition of the components included in the hard coating composition to be described later.

In one embodiment of the present invention, the transparent substrate may be made of a rigid or flexible material commonly used in the art. For example, polyethersulphone (PES), polyacrylate (PAR, polyacrylate), polyetherimide (PEI), polyethylene naphthalate (polyethyelenen napthalate), polyethylene terephthalate (PET) , Polyphenylene sulfide (PPS), polyallylate, polyimide (PI, polyimide), polycarbonate (PC, polycarbonate), cellulose triacetate (TAC), cellulose acetate propionate (CAP, cellulose acetate propionate), etc. may be used.

The thickness of the transparent substrate is not particularly limited, but may be 8 to 1000 μm, specifically 20 to 150 μm. When the thickness of the transparent substrate is less than 8 μm, the strength of the film is lowered, resulting in poor processability, and when it exceeds 1000 μm, the transparency decreases or the weight of the hard coating film increases.

In one embodiment of the present invention, the hard coating layer may be formed by applying a hard coating composition to the transparent substrate.

In one embodiment of the present invention, the hard coating composition may include a photocurable resin, a photoinitiator, and a solvent.

The photocurable resin may include a photocurable (meth)acrylate oligomer and/or monomer.

As the photocurable (meth)acrylate oligomer, epoxy (meth)acrylate, urethane (meth)acrylate, and the like are commonly used, and urethane (meth)acrylate is more preferable. The urethane (meth)acrylate can be prepared by reacting a polyfunctional (meth)acrylate having a hydroxy group in a molecule and a compound having an isocyanate group in the presence of a catalyst.

The polyfunctional (meth)acrylate having a hydroxy group in the molecule is 2-hydroxyethyl (meth)acrylate, 2-hydroxyisopropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone It may be selected from the group consisting of ring-opening hydroxyacrylate, pentaerythritol tri/tetra(meth)acrylate mixture, and dipentaerythritol penta/hexa(meth)acrylate mixture.

In addition, the compound having an isocyanate group is 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanatododecane, 1,5-di. Socyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, trans-1,4-cyclohexenediisocyanate, 4,4'-methylene Bis(cyclohexylisocyanate), isophorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethylxylene-1,3-di Isocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis (2,6-dimethylphenyl isocyanate), 4,4'-oxybis (phenyl isocyanate), derived from hexamethylene diisocyanate At least one type may be selected from the group consisting of trifunctional isocyanate, and trimethanepropanol adduct toluene diisocyanate.

The monomer may be one used in the art, and specifically, a compound having an unsaturated group such as a photocurable functional group, such as a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group, preferably (meth) It is a compound having an acryloyl group.

The monomer having the (meth)acryloyl group is neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene Glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate, 1,2 ,4-cyclohexanetetra(meth)acrylate, pentaglycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, di Pentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tri(meth)acrylate, tripentaerythritol hexatri(meth)acrylate, Bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, isooctyl(meth) ) Acrylate, isodexyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, and isoborneol (meth) acrylate One or more types may be selected from the group.

The photocurable resin may be included in an amount of 20 to 90% by weight, preferably 30 to 60% by weight, based on the total 100% by weight of the hard coating composition. If it is less than 20% by weight, it is difficult to increase the coating thickness, and it may be difficult to secure sufficient mechanical properties, and if it is more than 90% by weight, the coating property is significantly deteriorated, resulting in poor appearance and it may be difficult to ensure thickness uniformity.

The photoinitiator may be used without limitation as long as it is used in the art. Specifically, 2-methyl-1-[4-(methylthio)phenyl]2-morpholinepropanone-1, diphenylketone benzyldimethylketal, 2-hydroxy-2-methyl-1-phenyl-1-one , 4-hydroxycyclophenylketone, dimethoxy-2-phenylacetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-chronoloacetophenone, 4,4-dimethoxy At least one selected from the group consisting of acetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenylketone, and benzophenone may be used.

The photoinitiator may be included in an amount of 0.1 to 10% by weight based on 100% by weight of the total hard coating composition. When the content of the photoinitiator is less than 0.1% by weight, the curing speed is slow, and when it exceeds 10% by weight, cracks may occur in the hard coating layer due to excessive curing.

The solvent may be used without limitation as long as it is used in the art. Specifically, alcohol-based (methanol, ethanol, isopropanol, butanol, etc.), cellosolve-based (methylcellulose, ethylcellosolve, etc.), ketone-based (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl Ketone, dipropyl ketone, cyclohexanone, etc.), hexane-based (hexane, heptane, octane, etc.), benzene-based (benzene, toluene, xylene, etc.) may be used. Each of the solvents may be used alone or in combination of two or more.

The solvent may be included in 10 to 80% by weight, preferably 30 to 60% by weight, based on 100% by weight of the total hard coating composition. If it is less than 10% by weight, the viscosity is high and workability is deteriorated, and if it is more than 80% by weight, it takes a lot of time in drying and curing.

The hard coating composition may further include inorganic nanoparticles to further improve mechanical properties, especially hardness.

The inorganic nanoparticles may have an average particle diameter of 1 to 100 nm, preferably 5 to 50 nm. These inorganic nanoparticles are uniformly formed in the coating film to improve mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness. If the particle size is less than the above range, aggregation occurs in the composition, and the above effect cannot be expected. On the contrary, if the particle size exceeds the above range, the optical properties of the finally obtained coating film are deteriorated. Rather, there is a problem that mechanical properties are deteriorated.

The material of these inorganic nanoparticles may be metal oxides, and Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , ITO, IZO, ATO, ZnO- Al, Nb ₂ O ₃ , SnO, MgO, and one selected from the group consisting of a combination thereof may be used, and preferably Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like may be used. The inorganic nanoparticles may be prepared directly or purchased commercially and used. For commercially available products, those dispersed in an organic solvent at a concentration of 20 to 60% by weight may be used.

The inorganic nanoparticles may be included in an amount of 10 to 60% by weight based on 100% by weight of the total hard coating composition. If it is less than 10% by weight, mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness may not be sufficient, and when it is more than 60% by weight, the hardenability is hindered and the mechanical properties are rather deteriorated and the appearance may be poor.

In addition to the above components, the hard coating composition may additionally include components generally used in the art, for example, leveling agents, ultraviolet stabilizers, heat stabilizers, antioxidants, surfactants, lubricants, antifouling agents, and the like. .

The leveling agent may be used to impart smoothness and coatability of a coating film when coating the hard coating composition. The leveling agent may be a commercially available silicone type leveling agent, a fluorine type leveling agent, an acrylic polymer type leveling agent, etc., for example, BYK-323, BYK-331, BYK-333, BYK manufactured by BK Chem. -337, BYK-373, BYK-375, BYK-377, BYK-378, Daegu's TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, 3M's FC-4430, FC-4432, etc. can be used. The leveling agent is preferably used in the range of 0.1 to 1% by weight based on the total 100% by weight of the hard coating composition.

The hard coating layer may be formed by applying the hard coating composition to one or both sides of a transparent substrate, drying, and then UV curing.

The hard coating composition may be coated on a transparent substrate by appropriately using known methods such as die coater, air knife, reverse roll, spray, blade, casting, gravure, micro gravure, and spin coating.

After the hard coating composition is applied to the transparent substrate, the volatiles are evaporated and dried at a temperature of 30 to 150° C. for 10 seconds to 1 hour, more specifically for 30 seconds to 30 minutes, and then irradiated with UV light. To harden. The irradiation amount of the UV light may be specifically about 0.01 to 10J/cm2, and more specifically 0.1 to 2J/cm2.

In this case, the thickness of the formed hard coating layer may be specifically 5 to 150 μm, more specifically 10 to 100 μm. When the thickness of the hard coating layer is included within the above range, excellent hardness effects can be obtained.

The hard coating film according to an embodiment of the present invention may further include an adhesive layer or a buffer layer on the hard coating layer.

The adhesive layer is an intermediate layer formed to laminate an additional functional layer on the hard coating layer, and may be formed of a material and thickness commonly used in the art.

The buffer layer is a layer for preventing deformation of the hard coating layer, and may be formed using a material commonly used in the art, such as the above-described hard coating composition, and may have a thickness of 1 to 50 μm.

The hard coating film according to an embodiment of the present invention may further include a functional layer such as an antireflection layer and an additional hard coating layer on the adhesive layer or the buffer layer.

The antireflection layer is for preventing reflection of external light on the surface of the hard coating film, and may be formed of a material and thickness commonly used in the art.

The adhesive layer, the buffer layer, and the functional layer are preferably coated without patterning using a single coating solution in order to secure optical properties and adhesion.

One embodiment of the present invention relates to a flexible display provided with the above-described hard coating film. For example, the hard coating film of the present invention may be attached to a window of a flexible display.

The hard coating film according to an embodiment of the present invention may be used for a reflective type, a transmissive type, a transflective type LCD or a TN type, an STN type, an OCB type, a HAN type, a VA type, and an IPS type LCD of various driving methods. In addition, the hard coating film according to an embodiment of the present invention may be used in various image display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper.

As described above, specific parts of the present invention have been described in detail, and it is obvious that these specific techniques are only preferred embodiments and are not intended to limit the scope of the present invention for those of ordinary skill in the art to which the present invention belongs. Do. Those of ordinary skill in the art to which the present invention belongs will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Therefore, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (11)

Transparent substrate; And a hard coating layer formed on one or both sides of the transparent substrate, and partially or entirely patterned, as a hard coating film for a flexible display,
The hard coating layer alternately includes a rod-shaped first pattern area and a second pattern area to form a stripe shape, the first pattern area is formed of a hard hard coating composition, and the second pattern area is formed of a soft hard coating composition. Thus, a hard coating film for a flexible display in which the hardness of the first pattern area is greater than that of the second pattern area. delete The hard coating film of claim 1, wherein the widths of the first pattern area and the second pattern area are the same or different, and are 5 to 100 μm. The flexible display according to claim 1, wherein the hard coating layer further includes a third pattern area that is greater than the hardness of the first pattern area, and the first pattern area, the second pattern area, and the third pattern area are alternately positioned. Hard coating film. delete delete delete The hard coating film of claim 1, wherein the hard coating layer has a thickness of 5 to 150 μm. The hard coating film for a flexible display according to claim 1, further comprising an adhesive layer or a buffer layer on the hard coating layer. The hard coating film for a flexible display according to claim 9, further comprising an antireflection layer or a hard coating layer on the adhesive layer or the buffer layer. A flexible display provided with a hard coating film according to any one of claims 1, 3, 4, and 8 to 10.

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