KR20170122983A - Hard coating composition and hard coating film formed therefrom - Google Patents

Abstract

The present invention relates to a hard coating composition capable of preparing a hard coating film having excellent hardness, flexibility or abrasion resistance, and to a hard coating film using the same and, more specifically, to a hard coating composition comprising: layered silicate-structure nanoclay; and one or more types selected from a group consisting of polyfunctional (meth)acrylic dendrimer, polyfunctional (meth)acrylate including a cyclohexyl group and polyfunctional (meth)acrylate including an oxyethylene group, and to a hard coating film formed therefrom.

Description

TECHNICAL FIELD [0001] The present invention relates to a hard coating composition and a hard coating film formed therefrom. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

The present invention relates to a hard coating composition capable of forming a hard coating film protecting the display of an image display apparatus and a hard coating film formed therefrom.

Mobile devices that can bend or fold beyond curved smartphones that are simply curved in the near future will appear on the market. This is a product that adopts a flexible display type which is one step advanced from the commercialized curved display. Flexible display technology can be simply bent bendable in a bent curved, foldable in a foldable form, and finally rolled or rolled into a foldable form. It is expected to evolve into a stretchable form that can be increased or decreased.

Foldable display is a display that can be folded in half like a book or notebook, and various companies have proposed various technologies and patents. When the display is designed to be foldable, it can be used as a tablet when it is folded, and it can be used as a smartphone if it is folded. It can be used as a single product of different size. Devices can be doubled if they can be folded and carried.

Normally, in the case of a display, a cover window made of a glass material is provided at the outermost side to protect the display. However, in the case of glass, it is not applicable to a foldable display, and a hard hard coating film having high hardness and abrasion resistance to replace glass is used.

In order to ensure hardness of the glass level, it is necessary to increase the thickness of the hard coat layer in the hard coat film. As the thickness of the hard coat layer increases, the surface hardness can be increased. However, the hard coat layer is hardened and shrunk, Crack (or cracking) or peeling of the coating layer tends to occur, so that it is not easy to apply it practically.

On the other hand, as a method for improving abrasion resistance and scratch resistance, a method of adding a fine-powder inorganic filler or colloidal silica is generally known. However, even with the method of adding an inorganic filler or silica, there has been a problem of stability due to precipitation of colloidal silica particles whose surfaces are modified with organic substances or silanes and generation of gel, and the curing degree, optical transparency, Of course, abrasion resistance, scratch resistance and the like do not satisfy the conditions required in the hard coating film for protecting the display device.

Korean Patent No. 10-1451102 relates to an impact-resistant polyamide nanocomposite, which is characterized in that it contains polyamide oligomer, impact modifier, clay and triazine flame retardant in a specific range relative to 100 parts by weight of polyamide resin Sensitive polyamide nanocomposite. However, optical properties and flexibility of the polyamide nanocomposite are somewhat insufficient for application to a hard coating film.

Therefore, there is a need for the development of a hardcoat composition that is excellent in flexibility and satisfies abrasion resistance or scratch resistance.

Korean Registered Patent No. 10-1451102 (Oct. 20, 2014)

It is an object of the present invention to provide a hard coating composition capable of producing a hard coat film excellent in hardness, flexibility or scratch resistance.

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

It is also an object of the present invention to provide a window of an image display device or a display device including the aforementioned hard coating film.

In order to accomplish the above object, the hard coating composition of the present invention comprises a layered silicate structure nanoclay; And a polyfunctional (meth) acrylate including a polyfunctional (meth) acryl dendrimer, a polyfunctional urethane (meth) acrylate containing a cyclohexyl group, and an oxyethylene group. .

Further, the present invention provides an image display device provided with the above-mentioned hard coating film.

The present invention also provides a window of a display device provided with the above-mentioned hard coating film.

Since the hard coating composition according to the present invention includes nanoclays having a specific structure, it is possible to produce a hard coating film excellent in hardness and flexibility and excellent in scratch resistance, so that it can be applied to a window of a flexible display device It is applicable.

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

When a member is referred to as being " on "another member in the present invention, this includes not only when a member is in contact with another member but also when another member exists between the two members.

Whenever a part is referred to as "including " an element in the present invention, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

< Hard coating  Composition>

One aspect of the invention is a nanoclay of a layered silicate structure; (Meth) acrylate including a polyfunctional (meth) acryl dendrimer, a polyfunctional urethane (meth) acrylate containing a cyclohexyl group, and a polyfunctional (meth) acrylate containing an oxyethylene group. &Lt; / RTI &gt;

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

The total solids content of the hard coating composition in the present invention means the total content of the remaining components excluding the solvent from the hard coating composition.

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

Stratified Silicate  Structural Nano clay

The hard coating composition of the present invention comprises nanoclays of a layered silicate structure. The hard coating composition according to the present invention has the advantage of being able to improve scratch resistance and hardness because it contains the nano-clay.

The nano-clay of the layered silicate structure according to the present invention is a plate-like mineral having a length and a width of about 500 to 2000 Å and a thickness of 9 to 12 Å. The distance between each layer is about 10 Å, State, and the like.

In one embodiment of the present invention, the nano-clay may be at least one selected from the group consisting of montmorillonite, hectorite, vermiculite, saponite, bentonite, attapulgite, sepiolite, and mixtures thereof. Preferably, a selected layered silicate selected from the group consisting of commercially useful montmorillonite, hectorite, vermiculite, and saponite can be used.

The nano-clay may be purchased from, for example, Closite 20 manufactured by BYK, but is not limited thereto.

As the nano-clay, it is preferable to use one having a nano-scale particle size. More specifically, in another embodiment of the present invention, the nano-clay may have an average particle diameter of 1 to 100 nm. When the average particle diameter of the nano-clay satisfies the above range, it is preferable from the viewpoint of the process aspect and mechanical properties. When the average diameter of the nano-clay is less than 1 nm, the mechanical properties, specifically, scratch resistance and hardness may be somewhat improved. When the average diameter of the nano-clay is more than 100 nm, The transparency may be somewhat lowered.

The nano-clay is a plate-like clay mineral having a cation substitution capacity of 50 to 200 mg equivalent per 100 g. The nano-clay is ion-exchanged with an onium ion such as ammonium ion, quaternary ammonium ion or phosphonium ion containing an azo or peroxide group It can be easily reformed.

The nano-clay is preferably surface-treated with an organic modifier including an organic cation such as an onium ion to facilitate the penetration of organic materials between the clay layers. Specifically, examples of the organic modifier include dimethyl quaternary ammonium dihalophthalate quaternary ammonium, dimethyl dihydro phthaloalkyl ammonium chloride, dimethylhydrophthaloyl benzyl ammonium chloride, dimethyl 2-ethylhexyl hydrohaloalkyl ammonium chloride, dimethyl diethoxymethyl (2-hydroxyethyl) methylammonium chloride, vinylbenzyltrimethylammonium chloride, vinylbenzyltrimethylammonium chloride, vinylbenzyltrimethylammonium chloride, vinylbenzyltrimethylammonium chloride, vinyltrimethylammonium chloride, Benzyltrimethylammonium bromide, vinylbenzyltrimethylammonium iodide, vinylbenzyltriethylammonium chloride, vinylbenzyltriethylammonium bromide, vinylbenzyltriethylammonium iodide, 2-methacryloyloxyethyltrimethylammonium chloride, 2- Metaque Methacryloyloxyethyltrimethylammonium bromide, 2-methacryloyloxyethyltrimethylammonium iodide, 2-methacryloyloxyethyltriethylammonium chloride, 2-methacryloyloxyethyltriethylammonium bromide, 2- 2-acryloyloxyethyltrimethylammonium bromide, 2-acryloyloxyethyltrimethylammonium iodide, 2- acryloyloxyethyltrimethylammonium bromide, 2-acryloyloxyethyltrimethylammonium iodide, 2- Acryloyloxyethyltriethylammonium iodide, 3-methacryloylaminopropyltrimethylammonium chloride, 3-methacryloyloxyethyltrimethylammonium chloride, 2-acryloyloxyethyltriethylammonium bromide, 2- Methacryloylaminopropyltrimethylammonium bromide, 3-methacryloylaminopropyltrimethylammonium iodo Acryloylaminopropyltrimethylammonium bromide, 3-acryloylaminopropyltrimethylammonium iodide, diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyl dicyclohexylammonium bromide, Dimethylammonium iodide and the like are used. On the other hand, compounds having a vinyl group capable of radical polymerization can be used alone or as a mixture of two or more thereof.

In another embodiment of the present invention, the nano-clay is contained 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 preferable in view of mechanical properties and transparency.

When the nano-clay is included in the range of less than the above-mentioned range of 100 parts by weight of the total solid content of the hard coating composition, it may be difficult to exhibit the desired effect of the nano-clay. When the nano- It may be somewhat deteriorated, and therefore, it is preferable that it is included within the above range.

Polyfunctional (meth) acrylic Dendrimer

The hard coating composition according to the present invention comprises a polyfunctional (meth) acrylic dendrimer compound. The polyfunctional (meth) acryl dendrimer compound has a structural characteristic that it has more functional groups relative to the molecular weight as the generation increases, as compared with general multifunctional acrylate monomers, and the functional groups are distributed at the ends, thereby improving the bending property of the core portion There is a cause. Accordingly, there is an advantage that the effect of the hard hard coating layer having improved curl and flexibility can be imparted.

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

[Chemical Formula 1]

_{(R1) 4- n C (CH} 2 OR 2) n

In Formula 1,

n is an integer of 2 to 4,

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

이고,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) acryl dendrimer compound according to the present invention preferably has a structure of a second generation or more, and since the branch terminal is substituted with acrylate and can be used for ultraviolet curing, the function of the polymerizable compound in the hard coating composition Can be performed.

In the present invention, the number of carbon atoms of the alkyl group may be 1 to 10, preferably 1 to 6. Specific examples include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec- N-pentyl, 3-dimethylbutyl, 2-ethylbutyl, heptyl, n-hexyl, N-octyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethyl Heptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl and the like.

이고, 적어도 하나의 R3는

이며, x는 2 또는 3이고, R4는 수소 원자 또는 (메트)아크릴레이트기이며, 분자 내 적어도 하나의 R4는 (메트)아크릴레이트기일 수 있다.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 becomes a third-generation dendrimer compound, and at least one (meth) acrylate group is included at the branch ends, thereby performing the role of a polymerizable compound in the hard coating composition.

A dendrimer compound is a compound in which the chain of molecules is regularly polymerized from the center to the outside in accordance with a certain rule. In the dendrimer compound, a generic term refers to a compound in which a polymerizable functional group undergoes polymerization reaction based on the central part to form a branch , And when the first-generation branch ends of the formed first polymerization reaction proceed to the second generation, the polymerization reaction is repeatedly performed.

In the above formula, n, m and x represent the number of occurrences per generation, which means the number of polymerizable functional groups capable of undergoing polymerization in each generation, and the total number of synthesized dendrimer compounds is the number of occurrences per generation It means multiplication.

In the present invention, the dendrimer compound represented by the general formula (1) is a component which adjusts the molecular weight and crosslinking density of the polymer in an appropriate range in the polymerization reaction of the polymerizable component of the hard coating composition, And a photopolymerizable compound such as a polyfunctional (meth) acrylate containing a polyfunctional urethane (meth) acrylate or oxyethylene group including a cyclohexyl group. Specifically, the dendrimer compound of the formula (1) is polymerized so as to have branches in the outward direction on the basis of the central part in the polymerization reaction, and a polymerizable functional group is formed at the branch ends. As a result, compared with the polymerization reaction of the polymerizable compound having a general structure, it has more functional groups as compared with the increase in the molecular weight of the polymer, and therefore, it can realize excellent hardness characteristics.

In addition, since the dendrimer compound of formula (1) contains a polymerizable functional group only at the terminal, the polymer center portion can secure the appropriate flexibility, thereby securing the hardness of the hard coat layer and improving the curl characteristic and flexibility.

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

[Reaction Scheme 1]

As shown in the above reaction formula, the dendrimer compound according to an embodiment of the present invention forms a first-generation dendrimer structure in which DMPA is condensed at the center of TMP. Thereafter, DMPA is repeatedly condensed and polymerized repeatedly as a branched structure to continuously increase the generation of dendrimers. After the third generation, acrylic acid or the like is condensation-polymerized in the terminal group to form a dendrimer compound having a polyfunctional acrylic group at the terminal.

In the present invention, the dendrimer compound represented by the formula (1) has a structure of the second or third generation in the above-mentioned effect realization, and when the reaction proceeds over the third generation, gelation may occur.

In the present invention, the content of the dendrimer compound represented by the formula (1) is not particularly limited, but may be 10 to 50 parts by weight, preferably 20 to 40 parts by weight, based on 100 parts by weight of the entire hard coating composition. . When the above range is satisfied, excellent curvature can be ensured and curl characteristics and flexibility can be realized. When the dendrimer compound is in the above range, flexibility may be deteriorated. When the dendrimer compound is in the above range, the presence of unreacted functional groups due to the steric hindrance effect may make it difficult to secure alarm characteristics.

Cycloalkyl  Containing part Urethane (meth) acrylate

When the urethane (meth) acrylate compound is contained in the hard coating composition, sufficient hardness and scratch resistance can be secured.

The hard coating composition may comprise a urethane (meth) acrylate based compound comprising a cycloalkyl moiety. The term "including a cycloalkyl moiety" may refer to a case where a part of the compound includes 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 mono- or polysubstituted or unsubstituted. When the cycloalkyl moiety is substituted, the substituent may be an alkyl group such as methyl, ethyl, propyl, or a halogen group such as fluoro, chloro or bromo. The urethane (meth) acrylate resin containing the cycloalkyl moiety may be a polyfunctional 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, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, and the like, but are not limited thereto.

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

When the hard coating composition comprises a urethane (meth) acrylate-based compound containing the cycloalkyl moiety, it is possible to produce a hard coat film having improved mechanical properties. Specifically, when a hard coat film containing a hard coat layer containing a urethane (meth) acrylate compound containing the cycloalkyl moiety is prepared, it is possible to produce a hard coat film having an improved hardness.

The urethane (meth) acrylate compound containing the cycloalkyl moiety may be prepared by condensation reaction of a diisocyanate having a cycloalkyl group with a polyfunctional (meth) acrylate having a hydroxy group, but is not limited thereto.

The diisocyanate may include at least one 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 at least one of trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate .

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

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

(2)

(3)

When the urethane (meth) acrylate contains the cycloalkyl moiety, there is an advantage that the hardness can be improved due to the rigidity of the molecular structure of the cycloalkyl group. In addition, since the compound is stable to light as compared with an aryl group such as a phenyl group, there is an advantage that a hard coat composition having excellent optical characteristics can be produced.

In another embodiment of the present invention, the urethane (meth) acrylate compound containing the cycloalkyl moiety is contained in an amount of 15 to 45 parts by weight, preferably 20 to 40 parts by weight per 100 parts by weight of the entire hard coat composition It is preferable in terms of mechanical properties. If the urethane (meth) acrylate-based compound containing the cycloalkyl moiety is in the above range, the mechanical properties such as hardness may be somewhat lowered. If the urethane (meth) acrylate compound exceeds the above range, the shrinkage is somewhat increased, Etc. may occur.

Oxyethylene group  Included Polyfunctional (meth) acrylate series  compound

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

The polyfunctional (meth) acrylate-based compound containing oxyethylene group can be used without any limitations as commonly used in the art. The polyfunctional (meth) acrylate-based compound containing oxyethylene group may be at least one selected from the group consisting of trimethylol propane (EO) ₃ tri (meth) acrylate, trimethylol propane (EO) ₆ tri (meth) acrylate, trimethylol propane (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 (EO) ₁₂ hexa (meth) acrylate and dipentaerythritol (EO) ₁₈ hexa (meth) acrylate.

Specifically, the polyfunctional (meth) acrylate-based compound containing an oxyethylene group is obtained by subjecting a polyhydric alcohol to an addition reaction with ethylene oxide to obtain a polyfunctional alcohol having an ethylene glycol group, and then condensing (meth) acrylic acid with the polyfunctional alcohol But it is not limited thereto.

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

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

[Chemical Formula 4]

[Chemical Formula 5]

When the hard coating composition contains the polyfunctional (meth) acrylate compound, there is an advantage that a coating layer having improved durability can be produced. When the polyfunctional (meth) acrylate compound includes the oxyethylene group, flexibility There is also an advantage that can be given.

In another embodiment of the present invention, the amount of the polyfunctional (meth) acrylate compound containing oxyethylene group is 20 to 45 parts by weight, preferably 25 to 35 parts by weight, based on 100 parts by weight of the entire hard coating composition But are not limited thereto.

When the oxyalkylene group-containing polyfunctional (meth) acrylate compound is contained within the above range, it is possible to produce a hard coating film having excellent durability and flexibility. When the polyfunctional (meth) acrylate compound containing oxyethylene groups is contained in an amount less than the above range, the impartation of flexibility may be somewhat deteriorated, and when it exceeds the above range, securing of hardness may be somewhat difficult. .

In yet another embodiment of the present invention, the hard coat composition comprises a photoinitiator; solvent; And an additive selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers.

Photoinitiator

The photoinitiator is used for the photocuring of the hard coating composition, and can be applied without limitation as long as it is generally used in the art. Specifically, the photoinitiator may be a Type 1 initiator in which a radical is generated by decomposition of a molecule due to a difference in chemical structure or molecular binding energy, and a hydrogen recycle type Type 2 initiator coexisting with a tertiary amine.

Specific examples of the Type 1 initiator include 4-phenoxy dichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone, diethoxyacetophenone, 2- Methylpropane-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2- Acetophenones such as methylpropane-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone and 1-hydroxycyclohexylphenylketone, benzoin, Benzoates such as methyl ether, benzoin ethyl ether and benzyl dimethyl ketal, acylphosphine oxides and titanocene compounds.

Specific examples of the Type 2 type photoinitiator include benzophenone, benzoyl benzoic acid, benzoyl benzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3 ' -Methyl-4-methoxybenzophenone, benzophenones such as thioxanthone, 2-chromothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone and isopropylthioxanthone Oxanone, and the like.

These photoinitiators may be used alone or in combination of two or more. Type 1 and Type 2 may be used alone or in combination.

The photoinitiator may be used in an amount sufficient to allow photopolymerization to proceed, and 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 that hardness can be improved through polymerization between the compounds contained in the hard coating composition without affecting flexibility. If the amount of the photoinitiator is less than the above range, the curing may not progress sufficiently and the mechanical properties and adhesion of the finally obtained coating film may be somewhat difficult to achieve. If the amount exceeds the above range, It is preferable to use them appropriately within the above range.

solvent

The solvent is not limited as long as it is capable of dissolving or dispersing the above-mentioned composition and is known as a solvent of a composition for forming a coating layer in the technical field.

Specific examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol and propylene glycol methoxy alcohol, ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone and dipropyl ketone, (Such as methyl acetate, ethyl acetate, butyl acetate and propylene glycol methoxy acetate), cellosolves (methyl cellosolve, ethyl cellosolve and propyl cellosolve), hydrocarbons (normal hexane, normal heptane, benzene, toluene, Etc.). These solvents may be used alone 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, 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 amount of the solvent is less than the above range, the viscosity may be somewhat high and the workability may be deteriorated. If it exceeds the above range, it is difficult to control the thickness of the coating film, and drying unevenness may occur.

additive

The hard coating composition according to the present invention may further comprise additives, which may include, but are not limited to, inorganic nanoparticles, leveling agents and stabilizers.

(Inorganic nanoparticles)

The hard coating composition of the present invention may further comprise inorganic nanoparticles, and the inorganic nanoparticles may be inorganic nanoparticles having a reactive functional group. The inorganic nanoparticles having the reactive functional group may be selectively added to improve the hardness of the hard coat layer. Specifically, when the inorganic nanoparticles are included in the coating composition, the inorganic nanoparticles have an advantage of being able to further improve their mechanical properties. When the inorganic nanoparticles have the reactive functional groups, they can participate in the photo-curing reaction, There is an advantage that improvement can be made.

The reactive functional group may be an acryloyl group, a vinyl group such as a methacryloyl group or a vinyl ether, or a hydroxyl group, but is not limited thereto. The "inorganic nanoparticle having a reactive functional group" Quot; partially substituted with the above-mentioned reactive functional group.

For example, the inorganic nanoparticles having a reactive functional group may have a surface substituted with a (meth) acryl functional group, and in this case, they can participate in the photocuring reaction. In addition, the inorganic nanoparticles are uniformly formed in the coating film, and the mechanical properties such as abrasion resistance, scratch resistance and pencil hardness can be improved.

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

The inorganic nanoparticles may be formed of at least one of 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 may however comprise one or more of the group consisting of, and not limited to this may include a metal oxide that is commonly used in the art.

Specifically, the inorganic nanoparticles may be Al ₂ O ₃ , SiO ₂ , or ZrO ₂ whose surface is substituted with a (meth) acrylic functional group or a hydroxyl group. The inorganic nanoparticles may be prepared directly or commercially available ones. In the case of commercially available products, the inorganic nanoparticles may be dispersed in an organic solvent at a concentration of 10 to 80% by weight. 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). There may be commercially available products of inorganic nanoparticles whose surface is substituted with a hydroxyl group, such as IPA-ST, IPA-ST-L, IPA-ST-UP and IPA-ST-ZL (Nissan chemical) But is not limited thereto.

The inorganic nanoparticles having a reactive functional group can be prepared by surface modification using the above-mentioned reactive functional group, i.e., a compound containing a (meth) acrylic functional group. The surface modification treatment can be carried out by a conventional method such as chemical modification. Specifically, the surface modification treatment can be carried out by mixing the compound containing the reactive functional group and the inorganic nanoparticles selectively in a solvent, and 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, more preferably 5 to 15 parts by weight based on 100 parts by weight of the entire hard coating composition have. When the inorganic nanoparticles are contained in the above range, it is preferable in terms of imparting mechanical strength. If the inorganic nanoparticles are less than the above range, the mechanical properties such as abrasion resistance, scratch resistance and pencil hardness may not be sufficient. If the inorganic nanoparticles are more than 25 parts by weight, the mechanical properties may deteriorate and the appearance may be deteriorated have.

(Leveling agent)

The leveling agent may include at least one of a silicone leveling agent, a fluorine leveling agent, and an acrylic leveling agent. When the leveling agent is included in the hard coating composition, smoothness and coating properties can be imparted when the coating film is formed.

Specifically, the leveling agent may be selected from the group consisting of BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, BYK-SILCLEAN 3700, 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, 2300, TEGO Rad 2500, 3M FC-4430, FC-4432, etc., but the present invention is not limited thereto, and a leveling agent conventionally used in the art 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 contained in the hard coating composition within the above range, the smoothness and coatability of the coating film are maximized, and the hardness and flexibility can be maintained excellent.

(stabilizator)

The stabilizer may be a hindered amine type; Phenyl salicylate system; Benzophenone type; Benzotriazole systems; Nickel derivatives; Radical scavenger; Polyphenolics; Phosphite system; And a lactone-based stabilizer.

In the present invention, the ultraviolet stabilizer means an additive added for the purpose of shielding or absorbing ultraviolet rays to protect the hard coating composition, since the surface of the cured coating film is decomposed by continuous ultraviolet ray exposure to be discolored and crumbled.

The ultraviolet stabilizer may be classified into an absorbent, a quencher, and a hindered amine light stabilizer (HALS) according to the action mechanism. Also, depending on the chemical structure, it is possible to use Phenyl Salicylates (absorbent), Benzophenone (absorbent), Benzotriazole (absorber), Nickel derivative (quencher), Radical Scavenger .

In the present invention, there is no particular limitation as long as it is an ultraviolet stabilizer that does not greatly change the initial color of the hard coating composition.

The heat stabilizer is a commercially applicable product, and can be used either singly or as a mixture of a polyphenol as a primary heat stabilizer, a phosphite as a secondary heat stabilizer, and a lactone system. The ultraviolet stabilizer and the heat stabilizer can be appropriately used at a level at which the ultraviolet curing property is not affected.

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 in the above range of 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 the ultraviolet rays without lowering the hardness and flexibility, There is an advantage.

The hard coating composition according to the present invention comprises a nanoclay of a layered silicate structure; And a polyfunctional (meth) acrylate including a polyfunctional (meth) acryl dendrimer, a polyfunctional urethane (meth) acrylate including a cyclohexyl group, and an oxyethylene group are included together It has an advantage of being superior in hardness and flexibility as well as in scratch resistance as compared with the case where the above constitution is included singly.

The hard coating composition according to the present invention may contain, in addition to the above-mentioned components, a polymer compound, a light stimulant, an antioxidant, a UV absorber, a thermal polymerization inhibitor, An activator, a lubricant, an antifouling agent, and the like. At this time, selection and content control of each additive can be suitably selected by those skilled in the art.

< Hard coating  Film>

Another aspect of the invention relates to a hardcoat film comprising a cured product of the hardcoat composition described above.

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

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

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

In the present invention, the term "transparent" means that the transmittance of the visible ray is 70% or more or 80% or more. Incidentally, the case where the entire area is not transparent and the aperture ratio is 60% or more may be included.

The polymer film may be manufactured by a film-forming method or an extrusion method according to a manufacturing method, but is not limited thereto. Specifically, the transparent polymer film may be a cycloolefin-based derivative having a unit of a monomer including a cycloolefin such as norbornene or a polycyclic norbornene monomer, a cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, iso Propyl cellulose, butyryl cellulose, acetyl propionyl cellulose), ethylene vinyl acetate copolymer, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutyl Ren Terephthal Sites may be used polyethylene naphthalate, polycarbonate, polyurethane, and can be selected from among epoxy, non-stretched, uniaxially or biaxially stretched film.

More specifically, among the transparent substrates exemplified above, monoaxially or biaxially stretched polyester films excellent in transparency and heat resistance, cycloolefin-based derivative films excellent in transparency and heat resistance and capable of coping with the enlargement of the film, transparent and optically anisotropic A triacetylcellulose film having no transparency and a low transparency and a low cost acrylic copolymer film can be suitably used. However, the present invention is not limited thereto, and a substrate including a transparent plastic generally used in the art can be appropriately selected and used .

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

The thickness of the base film may be 8 to 1000 탆, specifically 40 to 100 탆. When the thickness of the base film is in the above-mentioned range, the strength of the film is high, so that the workability is excellent and the transparency is prevented from being lowered, and the hard coating film can be lightened.

The coating layer can be produced using the hard coating composition described above. Specifically, the coating layer may be formed by a suitable method such as die coater, air knife, reverse roll, spray, blade, casting, gravure, microgravure, and spin coating.

The thickness of the coating layer may be 3 占 퐉 to 200 占 퐉, specifically 10 占 퐉 to 100 占 퐉, more specifically, 20 占 퐉 to 30 占 퐉, but is not limited thereto. However, when the thickness of the coating layer satisfies the above range, there is an advantage that a hard coating film having excellent hardness, flexibility, thinning, and hardly causing curling phenomenon can be produced. The thickness of the coating layer may be referred to as the thickness after drying.

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

The hard coating film may be used for a flexible display. Specifically, the hard coating film may be used for a display such as LCD, OLED, LED, FED, various mobile communication terminals using the same, a cover glass for a touch panel of a smart phone or a tablet PC, Or as a functional layer.

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

The image display device may include a liquid crystal display device, an OLED, a flexible display, and the like. However, the present invention is not limited thereto, and any image display device known in the art can be applied.

Further, another aspect of the present invention relates to a window of a flexible display device including the aforementioned hard coating film.

Hereinafter, the present invention will be described in detail by way of examples to illustrate the present invention. However, the embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the above-described embodiments. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art. In the following, "%" and "part" representing the content are by weight unless otherwise specified.

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

Hard coating compositions were prepared with the ingredients as shown in Table 1 below. At this time, Closite 20 (manufactured by BYK) as a nano-clay, 3 generation of a multifunctional (meth) acryl dendrimer compound as a dendrimer, SOU-1700 (Shinya T & C) as a urethane (meth) acrylate compound and a polyfunctional (meth) MEK-AC-2140Z (Nissan chemical) as inorganic nanoparticles, Irgacure 184 (BASF) as a photoinitiator, BYK-333 (BYK) as a leveling agent, MEK (methyl ethyl ketone) was used as the other solvent.

Nano clay Dendrimer Urethane (meth) acrylate compound The polyfunctional (meth) acrylate compound Inorganic nanoparticle solvent Photoinitiator Leveling agent Closite 20 Third 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: Third generation of polyfunctional (meth) acrylic dendrimer compound

SOU-1700B (Shin-A T & C):

DPEA-126 (Japan Chemical):

M-340 (Miwon Specialty Chemical)

Hard coating  Production of film

The hard coating compositions prepared in Examples and Comparative Examples were each coated on an optical polyimide film (Mitsubishi Gas Chemical Co., Ltd., 100 占 퐉, L-3430) to a thickness of 20 占 퐉 and dried in an oven at 80 占 폚 for 2 minutes The hard coating film was prepared by curing at a light amount of 350 mJ in a high pressure mercury lamp.

Physical properties of the thus-prepared hard coating film were measured as described below, and the results are shown in Table 2 below.

(1) Pencil Hardness

The pencil hardness was measured by applying a load of 500 g using a pencil hardness tester (PHT, Korea Science and Engineering Corp.). The pencil was made five times per pencil hardness using Mitsubishi products. When two or more pieces of cigarettes were found to be defective, the maximum hardness determined as good was recorded.

Good 0: Good

Kith 1: Good

Gas 2 or higher: Bad

(2) Abrasion resistance

And scratch resistance was tested by reciprocating ten times under 1 kg / (2 cm x 2 cm) using a steel wool tester (WT-LCM100, Korea Protec Co.).

Steel wool used # 0000.

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 ~ 30 scratches

D: More than 31 scratches

(3) Adhesion

11 straight lines were drawn on the coated surface of the film at intervals of 1 mm to form 100 squares, and then peel test was performed three times using a tape (CT-24, Nichii Co., Ltd.). Three 100 squares were tested and the average was recorded. The adhesion was recorded as follows. That is, if none of them were peeled off, they were recorded as 100/100.

Adhesion = n / 100

n: the number of rectangles that are not to be peeled out of the entire rectangle

100: total number of squares

(4) Curl

A sample cut into a square of A4 size (29.7 x 21.0 cm) was placed on a flat glass plate with the coated side of the film facing up, and the distance from the four glass plates was measured at 25 DEG C and 50% RH, As a measurement value.

( 5) Mandrelle

In order to evaluate the bending property and the cracking property of the coating film, a coated film sample cut into a size of 1 cm × 10 cm was placed on the iron rod of each diameter (2φ to 20φ), and the coating layer was folded up by hand, 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 Abrasion resistance S S S S A D D D Adhesiveness 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 Mandrell 3φ 3φ 3φ 3φ 4φ 10φ 12φ 12φ

Referring to Table 2, it can be seen that the hard coating film according to the Example exhibited not only superior effects in pencil hardness, adhesiveness, curl and mandol test but also excellent scratch resistance test.

Claims (11)

Nanoclays of a layered silicate structure; And
A hard coating composition comprising at least one selected from the group consisting of a polyfunctional (meth) acryl dendrimer, a polyfunctional urethane (meth) acrylate containing a cyclohexyl group and a polyfunctional (meth) acrylate containing an oxyethylene group . The method according to claim 1,
Wherein the nano-clay is at least one selected from the group consisting of montmorillonite, hectorite, vermiculite, saponite, bentonite, attapulgite, sepiolite, and mixtures thereof. The method according to claim 1,
Wherein the nanoclay has an average particle diameter of 1 to 100 nm. The method according to claim 1,
Wherein the dendrimer compound is represented by the following Formula 1:
[Chemical Formula 1]
_{(R1) 4- n C (CH} 2 OR 2) n
In Formula 1,
n is an integer of 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. 5. The method of claim 4,
In Formula 1,
R3 is a hydrogen atom or

, And at least one R3 is

Lt;
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. The method according to claim 1,
Wherein the nano-clay 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. The method according to claim 1,
Wherein the polyfunctional (meth) acryl dendrimer is contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the entire hard coating composition. The method according to claim 1,
Photoinitiators; solvent; And an additive selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers. A hardcoat film comprising a cured product of the hard coating composition of any one of claims 1 to 8. An image display device comprising the hard coating film according to claim 9. A window of a flexible display device comprising a hard coating film according to claim 10.