KR102588664B1 - Hard coating composition and hard coating film formed therefrom - Google Patents

Abstract

The present invention relates to a hard coating composition and a hard coating film using the same, specifically nanoclay with a layered silicate structure; and a hard coating containing at least one member selected from the group consisting of polyfunctional (meth)acrylic dendrimer, polyfunctional urethane (meth)acrylate containing a cyclohexyl group, and polyfunctional (meth)acrylate containing an oxyethylene group. It relates to a composition and a hard coating film formed therefrom.

Description

Hard coating composition and hard coating film formed therefrom {HARD COATING COMPOSITION AND HARD COATING FILM FORMED THEREFROM}

The present invention relates to a hard coating composition capable of forming a hard coating film that protects a display of an image display device and a hard coating film formed therefrom.

In the near future, mobile devices that can be bent or folded, beyond simply curved smartphones that are fixed and bent, are expected to appear on the market. These are products that use a flexible display that is a step more advanced than the currently commercialized curved display. Flexible display technology has evolved from a simply curved form to a bendable form, a foldable form, and finally to a rollable form that can be rolled up or expanded in size. It is expected that it will evolve into a stretchable form that can be lengthened and shortened.

A foldable display is a display that can be folded in half like a book or notebook, and various technologies and patents are being proposed by several companies. If the display is designed in a foldable form, it can be used as a tablet when unfolded and as a smartphone when folded, so displays of different sizes can be used as one product, and the display can be larger like a tablet or TV than a small-sized smartphone. In the case of devices, convenience can be doubled if they can be folded and carried.

In the case of a typical display, a cover window made of glass is provided on the outermost side to protect the display. However, glass cannot be applied to foldable displays, and a high-hardness hard coating film with high hardness and wear resistance is used to replace glass.

In order to secure glass-level hardness, the thickness of the hard coating layer in the hard coating film must be thickened. As the thickness increases, the surface hardness can increase, but wrinkles and curls increase due to curing shrinkage of the hard coating layer, and at the same time, the hard coating layer becomes thicker. It is not easy to apply it practically because it is easy for cracks (or cracks) or peeling of the coating layer to occur.

Meanwhile, a method of adding fine-powder inorganic filler or colloidal silica is known as a method to improve wear resistance and scratch resistance. However, even with the method of adding inorganic fillers or silica, stability problems emerged due to precipitation and gel generation of colloidal silica particles whose silica surface was modified with organic substances or silane, and the degree of curing, optical transparency, and adhesion of the film were affected. Of course, wear resistance, scratch resistance, etc. do not meet the requirements required for hard coating films to protect display devices.

Republic of Korea Patent No. 10-1451102 relates to an impact-resistant polyamide nanocomposite. Specifically, it is characterized by containing polyamide oligomer, impact modifier, clay, and triazine-based flame retardant in a specific range based on 100 parts by weight of polyamide resin. Although it discloses information about an impact-resistant polyamide nanocomposite, its optical properties and flexibility are somewhat insufficient for application to hard coating films.

Therefore, there is a need to develop a hard coating composition that has excellent flexibility and satisfies wear resistance or scratch resistance.

Republic of Korea Patent No. 10-1451102 (2014.10.08)

The purpose of the present invention is to provide a hard coating composition that can produce a hard coating film with excellent hardness, flexibility, or scratch resistance.

Additionally, an object of the present invention is to provide a hard coating film with excellent hardness, flexibility, or scratch resistance.

Additionally, an object of the present invention is to provide an image display device or a window of a display device including the above-described hard coating film.

The hard coating composition of the present invention for achieving the above object includes nanoclay with a layered silicate structure; and polyfunctional (meth)acrylic dendrimer, polyfunctional urethane (meth)acrylate containing a cyclohexyl group, and polyfunctional (meth)acrylate containing an oxyethylene group. Do it as

Additionally, the present invention provides an image display device equipped with the above-described hard coating film.

Additionally, the present invention provides a window of a display device equipped with the above-described hard coating film.

Since the hard coating composition according to the present invention contains nanoclay of a specific structure, it is possible to manufacture a hard coating film with excellent hardness and flexibility and excellent scratch resistance, and therefore it can be used on windows of flexible display devices as well as image display devices. Applicable.

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

In the present invention, when a member is said to be located “on” another member, this includes not only the case where a member is in contact with another member, but also the case where another member exists between the two members.

In the present invention, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

< hard coating Composition>

One aspect of the present invention is nanoclay with a layered silicate structure; and a hard coating containing at least one member selected from the group consisting of polyfunctional (meth)acrylic dendrimer, polyfunctional urethane (meth)acrylate containing a cyclohexyl group, and polyfunctional (meth)acrylate containing an oxyethylene group. It relates to composition.

The hard coating composition of the present invention may further include additives and solvents such as inorganic nanoparticles having reactive functional groups.

In the present invention, the total solid content of the hard coating composition refers to the total content of the remaining components excluding the solvent from the hard coating composition.

For example, when inorganic nanoparticles are dispersed, only the inorganic nanoparticles are considered in the total solid content of the hard coating composition.

layered silicate structural nano clay

The hard coating composition of the present invention includes nanoclay with a layered silicate structure. The hard coating composition according to the present invention has the advantage of improving scratch resistance and hardness because it contains the nanoclay.

The nanoclay of the layered silicate structure according to the present invention is a plate-shaped mineral with a length and width of about 500 to 2000 Å and a thickness of 9 to 12 Å, and the distance between each layer is about 10 Å, and is usually a stack of such plate-shaped layers. It refers to a state that is in a condensed form.

In one embodiment of the present invention, the nanoclay may be one or more selected from the group consisting of montmorillonite, hectorite, vermiculite, saponite, bentonite, attapulgite, sepiolite, and mixtures thereof. Preferably, selected layered silicates selected from the group consisting of commercially available montmorillonite, hectorite, vermiculite, and saponite can be used.

The nanoclay can be purchased and used, for example, BYK's Closite 20, but is not limited to this.

It is preferable to use the nanoclay having a nano-level particle size. More specifically, in another embodiment of the present invention, the nanoclay may have an average particle diameter of 1 to 100 nm. If the average particle diameter of the nanoclay satisfies the above range, it is desirable in terms of process as well as mechanical properties. If the average diameter of the nanoclay is less than 1 nm, the improvement in mechanical properties, specifically scratch resistance and hardness, may be somewhat minimal, and if the average diameter of the nanoclay exceeds 100nm, aggregation between the nanoclay particles may occur. Transparency may be somewhat reduced as a result.

The nanoclay is a plate-shaped clay mineral with a cation exchange capacity of 50 to 200 mg equivalent per 100 g, and is exchanged through an ion exchange reaction with onium ions such as ammonium ions, quaternary ammonium ions, and phosphonium ions containing an azo group or peroxide group. Can be easily reformed.

The nanoclay is preferably surface-treated with an organic modifier containing organic cations such as onium ions to facilitate penetration of organic substances between clay layers. Specifically, the organic modifiers include dimethyl dihydrinated tallow alkyl ammonium chloride, dimethyl dihydrinated tallow alkyl ammonium chloride, dimethyl hydrated tallow alkyl benzyl ammonium chloride, dimethyl 2-ethylhexyl hydrated tallow alkyl ammonium chloride, and dimethyl diethoxymethyl. Hydrogenated tallowalkyl ammonium chloride, trimethyl hydrated tallowalkyl ammonium chloride, methyl tallow bis-2-hydroxyethyl quaternary ammonium, stearyl bis(2-hydroxyethyl)methyl ammonium chloride, vinylbenzyltrimethylammonium chloride, vinyl Benzyltrimethylammonium bromide, vinylbenzyltrimethylammonium iodide, vinylbenzyltriethylammonium chloride, vinylbenzyltriethylammonium bromide, vinylbenzyltriethylammonium iodide, 2-methacryloyloxy ethyl trimethylammonium chloride, 2- Methacryloyloxy ethyl trimethylammonium bromide, 2-methacryloyloxy ethyl trimethylammonium iodide, 2-methacryloyloxy ethyl triethylammonium chloride, 2-methacryloyloxy ethyl triethylammonium bromide, 2-Methacryloyloxy ethyl triethylammonium iodide, 2-acryloyloxy ethyl trimethylammonium chloride, 2-acryloyloxyethyl trimethylammonium bromide, 2-acryloyloxy ethyl trimethylammonium iodide, 2-acryloyloxy ethyltriethylammonium chloride, 2-acryloyloxy ethyl triethylammonium bromide, 2-acryloyloxy ethyl triethylammonium iodide, 3-methacryloylamino propyl trimethylammonium chloride, 3-Methacryloylamino propyl trimethylammonium bromide, 3-methacryloylamino propyl trimethylammonium iodide, 3-acryloylamino propyl trimethylammonium chloride, 3-acryloylamino propyl trimethylammonium bromide, 3- On one side is an onium ion that can undergo an ion exchange reaction with clay, and on the other side is a radical, such as acryloylamino propyl trimethylammonium iodide, diallyldimethyl ammonium chloride, diallyldimethyl ammonium bromide, and diallyldimethylammonium iodide. Compounds having a polymerizable vinyl group are used, and they can be used alone or in a mixture of more than one.

In another embodiment of the present invention, the nanoclay is included in an amount of 0.01 to 18 parts by weight, preferably 0.1 to 16 parts by weight, more preferably 0.5 to 16 parts by weight, based on 100 parts by weight of the total solid content of the hard coating composition. In this case, it is desirable in terms of mechanical properties and transparency.

If the nanoclay is contained in an amount less than the above range relative to 100 parts by weight of the total solid content of the hard coating composition, it may be somewhat difficult for the nanoclay to exhibit the desired effect, and if the nanoclay is contained in excess of the above range, transparency may decrease. Since it may be somewhat lowered, it is preferable that it is included within the above range.

Multifunctional (meth)acrylic type dendrimer

The hard coating composition according to the present invention includes a multifunctional (meth)acrylic dendrimer compound. The multifunctional (meth)acrylic dendrimer compound has the structural characteristic of having more functional groups compared to the molecular weight as the generation increases compared to general multifunctional acrylate monomers, and the distribution of functional groups at the terminals improves the bending characteristics of the core portion during curing. It can be attributed. Accordingly, there is an advantage in providing the effect of a high hardness hard coating layer with improved curl and flexibility.

In another embodiment of the present invention, the dendrimer compound is represented by the following formula (1).

[Formula 1]

(R1) _{4- n} C(CH ₂ OR ₂ ) _n

In Formula 1,

n is an integer from 2 to 4,

R1 is an alkyl group having 2 to 5 carbon atoms,

R2 is ego,

m is 2 or 3,

R3 is a hydrogen atom or a (meth)acrylate group, and at least one R3 in the molecule is a (meth)acrylate group.

In this case, the dendrimer compound of Formula 1 becomes a second-generation dendrimer compound. The multifunctional (meth)acrylic dendrimer compound according to the present invention preferably has a structure of the second generation or more, and the branched ends are substituted with acrylates and can be used for ultraviolet curing, so they play the role of a polymerizable compound in the hard coating composition. It can be done.

In the present invention, the alkyl group may have 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl. , isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n -Heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethyl Heptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, etc., but are not limited to these.

In some embodiments of the present invention, in Formula 1, R3 is a hydrogen atom or and at least one R3 is , x is 2 or 3, R4 is a hydrogen atom or a (meth)acrylate group, and at least one R4 in the molecule may be a (meth)acrylate group.

In this case, the dendrimer compound of Formula 1 is a third-generation dendrimer compound and contains at least one (meth)acrylate group at the branch end, thereby serving as a polymerizable compound in the hard coating composition.

A dendrimer compound is a compound in which the molecular chain polymerizes regularly from the center to the outside according to certain rules. In a dendrimer compound, a generation refers to a compound in which polymerizable functional groups undergo a polymerization reaction based on the center to form branches. Meaning, if the branch end of the first generation formed undergoes polymerization again, it becomes the second generation, and repeated polymerization reactions proceed.

In the above formula, n, m and It means multiplication.

In the present invention, the dendrimer compound represented by Formula 1 is a component that adjusts the molecular weight and crosslinking density of the polymer to an appropriate range during the polymerization reaction of the polymerizable component of the hard coating composition, and in this case, the polymerizable component includes the dendrimer compound, It may refer to photopolymerizable compounds such as polyfunctional urethane (meth)acrylate containing a cyclohexyl group or polyfunctional (meth)acrylate containing an oxyethylene group. Specifically, the dendrimer compound of Formula 1 is polymerized to have outward branches based on the center during the polymerization reaction, and a polymerizable functional group is formed at the end of each branch. Accordingly, compared to the polymerization reaction of a polymerizable compound of a general structure, more functional groups are obtained compared to the increase in molecular weight of the polymer, and thus excellent hardness characteristics can be realized.

In addition, since the dendrimer compound of Formula 1 contains a polymerizable functional group only at the ends, the center of the polymer can secure appropriate flexibility, thereby securing the hardness of the hard coating layer and improving curl characteristics and flexibility at the same time.

The schematic polymerization reaction formula of the dendrimer compound according to one embodiment of the present invention is as follows.

[Scheme 1]

As can be seen in the above reaction formula, the dendrimer compound according to an embodiment of the present invention forms a first-generation dendrimer structure by condensing DMPA with TMP as the center. Afterwards, the generation of dendrimer continues to increase by repeatedly condensation polymerizing DMPA as a branched structure, and after the third generation, a dendrimer compound having a multifunctional acrylic group at the end can be formed by condensation polymerization of acrylic acid or the like at the end group.

In the present invention, the dendrimer compound represented by Formula 1 preferably has a second- or third-generation structure to achieve the above-mentioned effects, and if the reaction proceeds beyond the third generation, gelation problems may occur.

In the present invention, the content of the dendrimer compound represented by Formula 1 is not particularly limited, but for example, it may be included in 10 to 50 parts by weight, preferably 20 to 40 parts by weight, based on 100 parts by weight of the total hard coating composition. You can. If the above range is satisfied, curl characteristics and flexibility can be achieved along with excellent hardness. If the dendrimer compound is less than the above range, flexibility may be reduced, and if it exceeds the above range, it may be somewhat difficult to secure alarm properties due to the presence of unreacted functional groups due to the steric inhibition effect.

cycloalkyl containing part Urethane (meth)acrylate

When the hard coating composition includes the urethane (meth)acrylate-based compound, sufficient hardness and scratch resistance can be secured.

The hard coating composition may include a urethane (meth)acrylate-based compound containing a cycloalkyl moiety. The term “containing a cycloalkyl moiety” may refer to a case where a part of the compound contains a cycloalkyl moiety. For example, the cycloalkyl moiety may be a monovalent cycloalkyl group or a divalent cycloalkylene group, and the cycloalkyl moiety may be singly or multiply substituted or unsubstituted. When the cycloalkyl moiety is substituted, the substituent may be an alkyl group such as methyl, ethyl, or propyl, or a halogen group such as fluoro, chloro, or bromo. The urethane (meth)acrylate resin containing the cycloalkyl moiety may be a multifunctional compound.

The cycloalkyl group is not particularly limited, but preferably has 3 to 40 carbon atoms. Specific examples include cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, Examples include, but are not limited to, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, and cyclooctyl.

The cycloalkylene group is not particularly limited, but preferably has 3 to 40 carbon atoms. Specifically, the cycloalkylene group is cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, methylcyclopentylene, dimethylcyclopentylene, methylcyclohexylene, and dimethylcyclohexylene. , may be cyclohexylene, and the description of the cycloalkyl group described above may be applied, except that the cycloalkylene group is a divalent group.

When the hard coating composition includes a urethane (meth)acrylate-based compound containing the cycloalkyl moiety, it is possible to manufacture a hard coating film with improved mechanical properties. Specifically, when manufacturing a hard coating film including a hard coating layer containing a urethane (meth)acrylate-based compound containing the cycloalkyl moiety, there is an advantage in that a hard coating film with improved hardness can be manufactured.

The urethane (meth)acrylate-based compound containing the cycloalkyl moiety can be prepared by condensing a diisocyanate having a cycloalkyl group and a polyfunctional (meth)acrylate having a hydroxy group, but is not limited thereto.

The diisocyanate may include one or more of the group consisting of 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, and 4,4-dicyclohexylmethane diisocyanate.

The polyfunctional (meth)acrylate containing the hydroxy group may include one or more of the group consisting of trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. You can.

The cycloalkyl group may be a cyclohexyl group. That is, the urethane (meth)acrylate-based compound containing a cycloalkyl moiety of the present invention may be a urethane (meth)acrylate-based compound containing a cyclohexyl group.

The urethane (meth)acrylate-based compound containing the cycloalkyl moiety may be represented by the following formula 2 or 3.

[Formula 2]

[Formula 3]

When the urethane (meth)acrylate includes the cycloalkyl moiety, there is an advantage that hardness can be improved due to the rigidity of the molecular structure of the cycloalkyl group. In addition, since it is more stable to light than an aryl group such as a phenyl group, it has the advantage of being able to produce a hard coating composition with excellent optical properties.

In another embodiment of the present invention, the urethane (meth)acrylate-based compound containing the cycloalkyl moiety is 15 to 45 parts by weight, preferably 20 to 40 parts by weight, based on 100 parts by weight of the total hard coating composition. It is preferable to include it in terms of mechanical properties. If the urethane (meth)acrylate-based compound containing the cycloalkyl moiety is less than the above range, mechanical properties such as hardness may be slightly lowered, and if it exceeds the above range, the shrinkage force is somewhat increased, causing curling, rupture, and cracking of the film. etc. may occur.

oxyethylene group containing Multifunctional (meth)acrylate type compound

The polyfunctional (meth)acrylate-based compound containing the oxyethylene group may be included to provide flexibility.

The polyfunctional (meth)acrylate-based compound containing the oxyethylene group can be used without limitation those commonly used in the field. The polyfunctional (meth)acrylate-based compound containing the oxyethylene group is trimethylolpropane (EO) ₃ tri(meth)acrylate, trimethylolpropane (EO) ₆ tri(meth)acrylate, and trimethylolpropane (EO). ₉ Tri(meth)acrylate, glycerin (EO) ₃ Tri(meth)acrylate, glycerin (EO) ₆ Tri(meth)acrylate, glycerin (EO) ₉ Tri(meth)acrylate, pentaerythritol (EO) ₄ Tetra(meth)acrylate, pentaerythritol (EO) ₈ Tetra(meth)acrylate, pentaerythritol (EO) ₁₂ Tetra(meth)acrylate, dipentaerythritol (EO) ₆ Hexa(meth)acrylate, dipentaerythritol At least one selected from the group consisting of (EO) ₁₂ hexa(meth)acrylate and dipentaerythritol (EO) ₁₈ hexa(meth)acrylate may be used.

Specifically, the polyfunctional (meth)acrylate-based compound containing the oxyethylene group is obtained by addition reaction of ethylene oxide to polyhydric alcohol to obtain polyfunctional alcohol having an ethylene glycol group, and condensing (meth)acrylic acid to the polyfunctional alcohol. It can be manufactured by reacting, but is not limited to this.

The polyfunctional alcohol may be a polyhydric alcohol, and may specifically be glycerol, trimethylolpropane, pentaerythritol, or dipentaerythritol, but is not limited thereto.

The polyfunctional (meth)acrylate-based compound containing the oxyethylene group may be represented by the following formula (4) or (5).

[Formula 4]

[Formula 5]

When the hard coating composition contains the polyfunctional (meth)acrylate-based compound, there is an advantage in manufacturing a coating layer with improved durability, and when the polyfunctional (meth)acrylate-based compound contains the oxyethylene group, it has the advantage of being flexible. There are also benefits that can be given.

In another embodiment of the present invention, based on 100 parts by weight of the hard coating composition, the polyfunctional (meth)acrylate-based compound containing the oxyethylene group is present in an amount of 20 to 45 parts by weight, preferably 25 to 35 parts by weight. It may be included as a part, but is not limited to this.

When the polyfunctional (meth)acrylate-based compound containing the oxyethylene group is contained within the above range, it is possible to manufacture a highly durable and flexible hard coating film. If the polyfunctional (meth)acrylate-based compound containing the oxyethylene group is contained below the above range, the imparting of flexibility may be somewhat reduced, and if it exceeds the above range, securing hardness may be somewhat difficult, so it is included within the above range. It is desirable to be

In another embodiment of the present invention, the hard coating composition includes a photoinitiator; solvent; and an additive selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers. It further includes at least one selected from the group consisting of.

photoinitiator

The photoinitiator is used for photocuring the hard coating composition, and can be applied without limitation as long as it is commonly used in the field. Specifically, the photoinitiator can be used as a type 1 initiator, which generates radicals by decomposition of molecules due to differences in chemical structure or molecular bond energy, and a type 2 initiator of the hydrogen recapture type by coexisting with a tertiary amine.

Specific examples of the Type 1 initiator include 4-phenoxydichloroacetphenone, 4-t-butyldichloroacetphenone, 4-t-butyltrichloroacetphenone, diethoxyacetphenone, 2-hydroxy-2-methyl- 1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2- Acetophenones such as methylpropan-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, benzoin, benzoin Benzoins such as methyl ether, benzoin ethyl ether, and benzyl dimethyl ketal, acylpocypine oxides, and titanocene compounds can be mentioned.

Specific examples of the Type 2 photoinitiator include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzole-4'-methyldiphenyl sulfide, 3,3' -Benzophenones such as methyl-4-methoxybenzophenone, teas such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, and isopropylthioxanthone Oxanthone, etc. can be mentioned.

The photoinitiator may be used alone or two or more types may be used in combination. Additionally, Type 1 and Type 2 may be used alone or in combination.

The photoinitiator is used in an amount that can sufficiently proceed with photopolymerization, and is not limited thereto, but may be included in an amount of 0.1 to 10 parts by weight, preferably 1 to 6 parts by weight, based on the total solid content of the hard coating composition.

When the photoinitiator is included within the above range, there is an advantage in that hardness can be improved through polymerization between compounds included in the hard coating composition without affecting flexibility. If the photoinitiator is less than the above range, curing may not proceed sufficiently, making it difficult to realize the mechanical properties or adhesion of the final manufactured coating film. If the photoinitiator exceeds the above range, poor adhesion, cracking, or curling may occur due to curing shrinkage. Since this may occur to some extent, it is desirable to use it appropriately within the above range.

solvent

The solvent can be used without limitation as long as it is capable of dissolving or dispersing the composition mentioned above and is known as a solvent for the composition for forming a coating layer in the present technical field.

Specifically, alcohol-based (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, etc.), ketone-based (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.), acetate-based (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellosolve type (methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.), hydrocarbon type (normal hexane, normal heptane, benzene, toluene, xyl Ren, etc.), etc. may be mentioned. The above solvents can be used individually or in combination of two or more.

The solvent may be included in an amount of 5 to 90 parts by weight, specifically 10 to 80 parts by weight, and more specifically 20 to 70 parts by weight, based on the total weight of the hard coating composition. When the solvent is included within the above range, it is preferable in terms of workability. If the solvent is less than the above range, the viscosity may be somewhat high and workability may be reduced, and if it exceeds the above range, it may be difficult to control the thickness of the coating film, and dry stains may occur, resulting in poor appearance.

additive

The hard coating composition according to the present invention may further include additives, and the additives may include one or more of the group consisting of inorganic nanoparticles, leveling agents, and stabilizers, but are not limited thereto.

(Inorganic nanoparticles)

The hard coating composition of the present invention may further include inorganic nanoparticles, and the inorganic nanoparticles may be inorganic nanoparticles having a reactive functional group. Inorganic nanoparticles having the reactive functional group can be selectively added to improve the hardness of the hard coating layer. Specifically, when the coating composition contains the inorganic nanoparticles, there is an advantage of further improving mechanical properties, and when the inorganic nanoparticles have the reactive functional group, they can participate in the photocuring reaction, resulting in better mechanical properties. There are advantages that can be improved.

The reactive functional group may be a vinyl group such as an acryloyl group, methacryloyl group, or vinyl ether, or a hydroxyl group, but is not limited thereto. The term "inorganic nanoparticle having a reactive functional group" refers to at least one surface of the inorganic nanoparticle. It refers to a product in which a part is substituted with the above reactive functional group.

For example, the inorganic nanoparticles having the reactive functional group may have a surface substituted with a (meth)acrylic functional group, and in this case, they have the characteristic of being able to participate in a photocuring reaction. In addition, there is an advantage in that the inorganic nanoparticles are uniformly formed within the coating film, improving mechanical properties such as wear resistance, scratch resistance, and pencil hardness.

The inorganic nanoparticles may have an average particle diameter of 1 to 100 nm, specifically 1 to 80 nm, and more specifically 5 to 50 nm. When the average particle diameter of the inorganic nanoparticles satisfies the above range, there is an advantage in that a uniform coating film can be formed by preventing agglomeration within the composition. In addition, it is possible to prevent the problem of deterioration of the optical properties and mechanical properties of the coating film.

The inorganic nanoparticles have reactive functional groups on at least part of the surface 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 -It may include one or more of the group consisting of Al, Nb ₂ O ₃ , SnO, MgO, and combinations thereof, but is not limited thereto and may include metal oxides commonly used in the art.

Specifically, the inorganic nanoparticles may be Al ₂ O ₃ , SiO ₂ , or ZrO ₂ whose surfaces are substituted with (meth)acrylic functional groups or hydroxyl groups. The inorganic nanoparticles can be manufactured directly or purchased commercially, and in the case of commercially available products, those dispersed in an organic solvent at a concentration of 10 to 80% by weight can be used. Commercially available products of inorganic nanoparticles whose surfaces are substituted with (meth)acrylic functional groups include, but are not limited to, MEK-AC-2140Z, MEK-AC-4130Y, and MEK-AC-5140Z (Nissan Chemical). In addition, commercially available products of inorganic nanoparticles with surfaces substituted with hydroxyl groups include, for example, IPA-ST, IPA-ST-L, IPA-ST-UP, IPA-ST-ZL (Nissan Chemicals), etc. It is not limited to this.

Inorganic nanoparticles having the reactive functional group can be manufactured by surface modification using a compound containing the reactive functional group, that is, a (meth)acrylic functional group. The surface modification treatment can be carried out according to conventional methods such as chemical modification, and specifically, it can be carried out by selectively mixing the compound containing the reactive functional group and the inorganic nanoparticles in a solvent, followed by heating and stirring.

In some embodiments of the present invention, the inorganic nanoparticles may be included in an amount of 1 to 25 parts by weight, preferably 5 to 20 parts by weight, and more preferably 5 to 15 parts by weight, based on 100 parts by weight of the total hard coating composition. there is. When the inorganic nanoparticles are included in the above range, it is preferable in terms of providing mechanical strength. If the inorganic nanoparticles are less than the above range, mechanical properties such as wear resistance, scratch resistance, and pencil hardness may not be sufficient, and if it exceeds 25 parts by weight, curability may be hindered, resulting in lower mechanical properties and poor appearance. there is.

(Leveling system)

The leveling agent may include one or more of the group consisting of a silicone-based leveling agent, a fluorine-based leveling agent, and an acrylic-based leveling agent. When the leveling agent is included in the hard coating composition, there is an advantage in that smoothness and coating properties can be imparted when forming a coating film.

Specifically, the leveling agent is BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, BYK-SILCLEAN 3700 from BYK Chemistry, and BYK-SILCLEAN 3700 from Daegu. 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, but are not limited to these, and leveling agents commonly used in the industry can be applied.

The leveling agent may be included in an amount of 0.1 to 3 parts by weight based on the total weight of the hard coating composition, but is not limited thereto. However, when the leveling agent is included within the above range for the hard coating composition, there is an advantage in that the smoothness and coating properties of the coating film are maximized while maintaining excellent hardness and flexibility.

(stabilizator)

The stabilizer is a hindered amine type; phenyl salicylate type; Benzophenone series; Benzotriazole series; Nickel derivative; radical scavenger; polyphenols; Phosphite series; And it may include one or more of the group consisting of lactone-based stabilizers.

In the present invention, an ultraviolet stabilizer refers to an additive added for the purpose of protecting the hard coating composition by blocking or absorbing ultraviolet rays, since the surface of the cured coating film is decomposed by continuous exposure to ultraviolet rays, causing discoloration and brittleness.

The UV stabilizers can be classified into absorbers, quenchers, and hindered amine light stabilizers (HALS) depending on their mechanism of action. In addition, depending on the chemical structure, it is classified into phenyl salicylates (absorbent), benzophenone (absorbent), benzotriazole (absorbent), nickel derivative (quencher), and radical scavenger. can be distinguished.

In the present invention, there is no particular limitation as long as the UV stabilizer does not significantly change the initial color of the hard coating composition.

Heat stabilizers are commercially applicable products, and polyphenol-based primary heat stabilizers, phosphite-based and lactone-based secondary heat stabilizers can be used alone or in combination. The UV stabilizer and heat stabilizer can be used by appropriately adjusting the content to a level that does not affect UV curing properties.

The stabilizer may be included in an amount of 0.1 to 10 parts by weight based on the total solid content of the hard coating composition, but is not limited thereto. When the stabilizer is contained within the above range relative to the total solid content of the hard coating composition, it is possible to prevent the surface of the cured coating film from being decomposed by ultraviolet rays without reducing hardness and flexibility, and does not affect ultraviolet curability. There is an advantage to not having it.

The hard coating composition according to the present invention includes nanoclay with a layered silicate structure; and polyfunctional (meth)acrylic dendrimer, polyfunctional urethane (meth)acrylate containing a cyclohexyl group, and polyfunctional (meth)acrylate containing an oxyethylene group. There is an advantage in that hardness and flexibility are superior to those in which the above components are included alone, as well as excellent scratch resistance.

In addition to the above-mentioned ingredients, the hard coating composition according to the present invention includes polymer compounds commonly used in the field, photostimulants, antioxidants, UV absorbers, thermal polymerization inhibitors, and interface agents, as long as they do not reduce the effectiveness of the present invention. It may further contain activators, lubricants, antifouling agents, etc. At this time, the selection and content control of each additive can be appropriately selected by those skilled in the art.

< hard coating Film>

Another aspect of the present invention relates to a hard coating film comprising a cured product of the above-described hard coating composition.

For example, the hard coating film may be formed by applying the above-described hard coating composition to one or both sides of a transparent base film and then curing it.

The hard coating film manufactured using the hard coating composition according to the present invention described above exhibits excellent hardness and flexibility.

The base film is not limited as long as it is a transparent polymer film.

In the present invention, “transparent” means that the transmittance of visible light is 70% or more or 80% or more. In addition, cases where the entire area is not transparent and the aperture ratio is 60% or more may be included.

The polymer film can be manufactured by a film forming method or an extrusion method depending on the manufacturing method, but is not limited thereto. Specifically, the transparent polymer film is a cycloolefin-based derivative having a unit of a cycloolefin-containing monomer such as norbornene or polycyclic norbornene-based monomer, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isomethylcellulose) Butyl ester cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose), ethylene vinyl acetate copolymer, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyethersulfone, polysulfone, polyethylene , polypropylene, polymethyl pentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutyl You can choose from lentrephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy, and unstretched, uniaxially or biaxially oriented films can be used.

More specifically, among the transparent substrates exemplified above, uniaxially or biaxially oriented polyester films with excellent transparency and heat resistance, cycloolefin-based derivative films that have excellent transparency and heat resistance and can cope with the enlargement of films, transparency and optically anisotropic Triacetylcellulose film without porosity and acrylic copolymer film with high transparency and low cost can be suitably used, but it is not limited thereto, and a substrate containing transparent plastic commonly used in the industry can be appropriately selected and used. .

Plasma or corona treatment may be performed before forming the coating layer on the base film, but is not limited thereto. When pretreatment such as plasma or corona treatment is performed on the base film, there is an advantage in that the adhesion between the coating layer and the base film is increased. The plasma or corona treatment can be performed by a method generally used in the art.

The thickness of the base film may be 8 to 1000 μm, specifically 40 to 100 μm. When the thickness of the base film is within the above range, the strength of the film is high, so processability is excellent, a decrease in transparency can be prevented, and the weight of the hard coating film can be reduced.

The coating layer can be manufactured using the hard coating composition described above. Specifically, the coating layer can be formed by an appropriate method such as die coater, air knife, reverse roll, spray, blade, casting, gravure, micro gravure, and spin coating.

The thickness of the coating layer may be 3 ㎛ to 200 ㎛, specifically 10 ㎛ to 100 ㎛, more specifically 20 ㎛ to 30 ㎛, but is not limited thereto. However, when the thickness of the coating layer satisfies the above range, there is an advantage in producing a hard coating film that has excellent hardness and flexible properties, can be thinned, and hardly causes curling. The thickness of the coating layer may refer to the thickness after drying.

After applying the hard coating composition, it is dried by evaporation of volatile substances at a temperature of 30 to 150°C for 10 seconds to 1 hour, specifically 30 seconds to 10 minutes. Afterwards, the hard coating composition is cured by irradiating UV light. The irradiation amount of the UV light may be about 0.01 to 10 J/cm ² , specifically 0.1 to 2 J/cm ² .

The hard coating film may be used for flexible displays, and is specifically used to replace cover glass for displays such as LCD, OLED, LED, and FED, various mobile communication terminals using the same, touch panels for smartphones or tablet PCs, and electronic paper. Alternatively, it can be used as a functional layer.

Another aspect of the present invention relates to an image display device including the above-described hard coating film.

The image display device may include a liquid crystal display device, OLED, flexible display, etc., but is not limited thereto and may include any image display device known in the art that can be applied.

Additionally, another aspect of the present invention relates to a window of a flexible display device including the above-described hard coating film.

Hereinafter, examples will be given in detail to explain the present specification in detail. However, the embodiments according to the present specification may be modified into various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described in detail below. The embodiments of this specification are provided to more completely explain the present specification to those with average knowledge in the art. In addition, "%" and "part" indicating content below are based on weight, unless otherwise specified.

Example 1 to 5 and Comparative example 1 to 3: hard coating Preparation of composition

A hard coating composition was prepared using the ingredients shown in Table 1 below. At this time, Closite 20 (BYK) as nanoclay, 3rd generation multifunctional (meth)acrylic dendrimer compound as dendrimer, and SOU-1700 (Shinah T&C) as urethane (meth)acrylate compound, multifunctional (meth)acrylate compound. DPEA-126 (Japan Chemical) and M-340 (Miwon Specialty Chemicals) as compounds, MEK-AC-2140Z (Nissan Chemicals) as inorganic nanoparticles, Irgacure 184 (BASF) as photoinitiator, BYK-333 (BYK) as leveling agent. G) was used, and MEK (methyl ethyl ketone) was used as an additional solvent.

nano clay dendrimer Urethane (meth)acrylate-based compounds Multifunctional (meth)acrylate-based compounds inorganic nanoparticles solvent photoinitiator leveling agent Closite 20 3rd generation SOU-1700B DPEA-126 M-340 MEK-AC-2140Z Methyl ethyl ketone Irgacure 184 BYK-333 Example 1 5 40 - - - 5 46.7 3 0.3 Example 2 5 20 40 - - - 31.7 3 0.3 Example 3 8 - - 35 - 5 48.7 3 0.3 Example 4 8 - - - 35 5 48.7 3 0.3 Example 5 8 40 - - - - 48.7 3 0.3 Comparative Example 1 - - 40 21.7 - - 35 3 0.3 Comparative Example 2 - - 40 - 21.7 - 35 3 0.3 Comparative Example 3 - 40 - - - 5 51.7 3 0.3

Dendrimer: 3rd generation multifunctional (meth)acrylic dendrimer compound

SOU-1700B (Shinah T&C):

DPEA-126 (Japan Chemical):

M-340 (Miwon Specialty Chemical)

hard coating Manufacturing of Film

The hard coating compositions prepared in Examples and Comparative Examples were dried on one side of an optical polyimide film (Mitsubishi Gas Chemical, 100㎛, L-3430) and then coated to a thickness of 20㎛, dried in an oven at 80 degrees for 2 minutes. A hard coating film was manufactured by curing in a high-pressure mercury lamp with a light intensity of 350 mJ.

The physical properties of the manufactured hard coating film were measured as follows, and the results are shown in Table 2 below.

(1) Pencil hardness

The pencil hardness was measured using a pencil hardness tester (PHT, Seokbo Science, Korea) with a 500g load. The pencil was a Mitsubishi product, and the test was conducted 5 times per pencil hardness. If there were two or more scratches, it was judged as defective, and the maximum hardness judged as good was recorded.

Scratch 0: Good

Geese 1: Good

Geese 2 or higher: Bad

(2) scratch resistance

Scratch resistance was tested by reciprocating 10 times under 1kg/(2cm×2cm) using a steel wool tester (WT-LCM100, Korea Protex).

#0000 steel wool was used.

S: 0 scratches

A: 1 to 10 scratches

B: 11 to 20 scratches

C: 21 to 30 scratches

D: 31 or more scratches

(3) Adhesion

Eleven straight lines were drawn horizontally and vertically at 1 mm intervals on the coated surface of the film to create 100 squares, and then a peeling test was performed three times using tape (CT-24, Nichibang Corporation, Japan). Three 100 squares were tested and the average value was recorded. Adhesion was recorded as follows. That is, if no peeling occurred, it was recorded as 100/100.

Adhesion = n/100

n: Number of squares that are not peeled out of all squares

100: Total number of squares

(4) Curl

A sample cut into a square shape of A4 size (29.7 It was used as the measured value.

( 5)Mandorel

To evaluate the bending characteristics and cracking properties of the coating film, a coated film sample cut to a size of 1cm The smallest diameter that does not occur is indicated.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 pencil hardness 6H 5H 6H 6H 5H H F F scratch resistance S S S S A D D D Adhesion 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 curl 4mm 4mm 4mm 4mm 4mm 12mm 11mm 13mm mandorel 3ϕ 3ϕ 3ϕ 3ϕ 4ϕ 10ϕ 12ϕ 12ϕ

Referring to Table 2, it was found that the hard coating film according to the example not only showed excellent effects in pencil hardness, adhesion, curl, and mandorel tests, but also had particularly excellent effects in the scratch resistance test.

Claims (11)

Nanoclay with layered silicate structure; and
A hard coating composition containing at least one member selected from the group consisting of polyfunctional (meth)acrylic dendrimer, polyfunctional urethane (meth)acrylate containing a cyclohexyl group, and polyfunctional (meth)acrylate containing an oxyethylene group. as,
A hard coating composition in which the multifunctional (meth)acrylic dendrimer is represented by the following formula (1):
[Formula 1]
(R1) _4-n C(CH ₂ OR ₂ ) _n
In Formula 1,
n is an integer from 2 to 4,
R1 is an alkyl group having 2 to 5 carbon atoms,
R2 is ego,
m is 2 or 3,
R3 is a hydrogen atom or and at least one R3 is and
x is 2 or 3,
R4 is a hydrogen atom or a (meth)acrylate group, and at least one R4 in the molecule is a (meth)acrylate group. According to paragraph 1,
A hard coating composition wherein the nanoclay is at least one selected from the group consisting of montmorillonite, hectorite, vermiculite, saponite, bentonite, attapulgite, sepiolite, and mixtures thereof. According to paragraph 1,
The nanoclay is a hard coating composition having an average particle diameter of 1 to 100 nm. delete delete According to paragraph 1,
A hard coating composition in which the nanoclay is contained in an amount of 0.01 to 18 parts by weight based on 100 parts by weight of the total solid content of the hard coating composition. According to paragraph 1,
A hard coating composition in which the multifunctional (meth)acrylic dendrimer is contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the total hard coating composition. According to paragraph 1,
photoinitiator; solvent; and an additive selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers. A hard coating composition further comprising at least one selected from the group consisting of. A hard coating film comprising a cured product of the hard coating composition of any one of claims 1 to 3 and 6 to 8. An image display device comprising the hard coating film according to claim 9. A window of a flexible display device comprising the hard coating film according to claim 9.