KR20170006515A - Compositon for hard coating, optical film and display device using the same - Google Patents

Abstract

The present invention relates to a composition for forming hard coating. More specifically, the present invention relates to a composition for forming hard coating, which comprises a dendrimer compound (A) having a specific structure, a photopolymerizable compound (B), a photopolymerization initiator (C), and a solvent (D), thereby creating proper curing density, securing hardness in hard coating layers, and remarkably increasing curling properties and flexibility. The present invention further relates to an optical film using the same, and an image display device.

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for forming a hard coating, an optical film using the composition, and an image display device using the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a composition for forming a hard coating, an optical film using the composition, and an image display device.

BACKGROUND ART [0002] Recently, a thin display device using a flat panel display device such as a liquid crystal display or an organic light emitting diode (OLED) display has received great attention. Particularly, these thin display devices are realized in the form of a touch screen panel, and are characterized by being portable not only in a smart phone, a tablet PC, but also in various wearable devices It is widely used in various smart devices.

These portable touch screen panel-based display devices are provided with a window film for display protection on a display panel to protect the display panel from scratches or external impacts. In most cases, tempered glass for display is used as a window film. Tempered glass for displays is thinner than ordinary glass, but is characterized by high strength and scratch resistance.

However, since the tempered glass has a disadvantage that it is not suitable for weight reduction of a portable device due to its heavy weight, it is difficult to realize an unbreakable property because it is vulnerable to an external impact, and is not bendable, It is not suitable as a flexible display material having a foldable function.

In recent years, studies on optical plastic covers having strength or scratch resistance corresponding to tempered glass, while ensuring flexibility and impact resistance, have been made variously. Polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyacrylate (PAR), polycarbonate (PC) , Polyimide (PI), and the like. However, these polymer plastic substrates not only exhibit physical properties insufficient in terms of hardness and scratch resistance as compared with tempered glass used as a window film for display protection, but also have insufficient impact resistance. Therefore, various attempts have been made to complement the physical properties required by coating the composite resin composition on these plastic substrates.

Accordingly, in the case of general hard coating, a composition comprising a resin containing a photo-curable functional group, a curing agent, a curing catalyst, and other additives is used. In particular, a high functional group In the case of a composite resin, it can be coated on an optical plastic substrate film to be used as a display protection window having improved hardness and scratch resistance.

However, in the case of a general photocurable composite resin, it is difficult to realize a high hardness corresponding to tempered glass, curl phenomenon due to shrinkage during curing is largely generated, and flexibility is not sufficient, It is not suitable as a protective window film.

Korean Patent Laid-Open Publication No. 2013-74167 discloses a plastic substrate.

Korea Patent Publication No. 2013-74167

It is an object of the present invention to provide a composition for forming a hard coating capable of simultaneously realizing hardness and flexibility and capable of producing a hardcoat film in which curling is suppressed.

It is another object of the present invention to provide an optical film having a hard coating layer formed of the composition for forming a hard coating.

It is another object of the present invention to provide an image display apparatus having the optical film.

1. A hard coating composition comprising a dendrimer compound (A) represented by the following formula (1), a photopolymerizable compound (B), a photopolymerization initiator (C) and a solvent (D)

[Chemical Formula 1]

(R ₁ ) _{4- n} C (CH ₂ OR ₂ ) _n

(Wherein n is an integer of 2 to 4,

R ₁ is an alkyl group having 2 to 5 carbon atoms,

이고,R ₂ is

ego,

m is 2 or 3,

R ₃ is a hydrogen atom or a (meth) acrylate group, and at least one R ₃ in the molecule is a (meth) acrylate group.

2. The compound according to 1 above, wherein in the formula 1,

이고, 적어도 하나의 R₃는

이며,R ₃ is a hydrogen atom or

And at least one R < ₃ >

Lt;

X is 2 or 3,

R ₄ is a hydrogen atom or a (meth) acrylate group, and at least one R ₄ in the molecule is a (meth) acrylate group.

3. The dendrimer compound (A) as described in the above 1, wherein the dendrimer compound (A) is contained in an amount of 10 to 50 parts by weight per 100 parts by weight of the total of the polymerizable components (A) and (B) Composition for forming a coating.

4. The composition for forming a hard coating according to 1 above, wherein the photopolymerizable compound (B) comprises at least one member selected from the group consisting of urethane-based (meth) acrylate and (meth) acrylate containing oxyethylene group.

5. The composition for forming a hard coating according to 4 above, wherein the urethane-based (meth) acrylate is substituted with a cyclohexyl group.

6. The composition for forming a hard coat according to 1 above, wherein the photopolymerization initiator (C) is at least one selected from the group consisting of an acetophenone-based photoinitiator and an amino ketone-based photoinitiator.

7. The composition for forming a hard coat according to 1 above, further comprising inorganic nanoparticles.

8. An optical film comprising at least one surface of a base film and a coating layer formed of the composition for forming a hard coating as described in any one of the above items 1 to 7.

9. The optical film according to the above 8, wherein the optical film is a window film.

10. An image display device comprising the above optical film.

The composition for forming a hard coating of the present invention includes a dendrimer compound having a specific structure, so that a proper hardening density can be realized, thereby making it possible to secure hardness of the hard coating layer and simultaneously improve the curling property and flexibility.

In addition, the composition for forming a hard coating of the present invention is suitable for flexible displays with excellent curl characteristics and flexibility.

More particularly, the present invention relates to a composition for forming a hard coating, which comprises a dendrimer compound (A), a photopolymerizable compound (B), a photopolymerization initiator (C) and a solvent (D) The present invention relates to a composition for forming a hard coating and an optical film and an image display device using the composition for forming a hard coating which can secure hardness of a hard coating layer and simultaneously improve curling property and flexibility.

Hereinafter, the present invention will be described in detail.

< Hard coating  Composition for forming &gt;

The composition for forming a hard coating of the present invention comprises a dendrimer compound (A) having a specific structure, a photopolymerizable compound (B), a photopolymerization initiator (C) and a solvent (D).

Dendrimer  The compound (A)

The composition for forming a hard coating according to the present invention comprises a dendrimer compound (A) represented by the following formula (1).

[Chemical Formula 1]

(R ₁ ) _{4- n} C (CH ₂ OR ₂ ) _n

Wherein n is an integer of 2 to 4,

R ₁ is an alkyl group having 2 to 5 carbon atoms,

이고,R ₂ is

ego,

m is 2 or 3,

R ₃ is a hydrogen atom or a (meth) acrylate group, and at least one R ₃ in the molecule is a (meth) acrylate group.

In this case, the dendrimer compound of the formula (1) becomes a second-generation dendrimer compound, and at least one (meth) acrylate group is contained at the branch ends, thereby performing the role of a polymerizable compound in the composition for forming a hard coating.

이고, 적어도 하나의 R₃는

이며, X는 2 또는 3이고, R₄는 수소 원자 또는 (메타)아크릴레이트기이며, 분자 내 적어도 하나의 R₄는 (메타)아크릴레이트기일 수 있다. According to another embodiment of the present invention, the dendrimer compound is a compound represented by the general formula (1) wherein R ₃ is a hydrogen atom or

And at least one R &lt; ₃ &gt;

, X is 2 or 3, R ₄ is a hydrogen atom or a (meth) acrylate group, and at least one R ₄ in the molecule may be a (meth) acrylate group.

In this case, the dendrimer compound of the formula (1) becomes a third generation dendrimer compound, and at least one (meth) acrylate group is contained at the branch ends, thereby performing the role of a polymerizable compound in the composition for forming a hard coating.

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 that adjusts the molecular weight and crosslinking density of the polymer in an appropriate range during the polymerization reaction of the polymerizable components (A) and (B) in the composition for forming a hard coating . 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, since the polymer has more functional groups than the middle molecular weight of the polymer, excellent hardness characteristics can be realized.

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 an 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 general formula (1) has a structure of the second or third generation in the above-mentioned effect realization, and when the reaction proceeds over three generations, gelation occurs.

In the present invention, the content of the dendrimer compound represented by the general formula (1) is not particularly limited, but it is preferably 10 to 50 parts by weight per 100 parts by weight of the polymerizable component (mixed weight of (A) and (B) And preferably 20 to 40 parts by weight. When the above range is satisfied, excellent curvature can be ensured and curl characteristics and flexibility can be realized. When the amount is less than 10 parts by weight, flexibility may be deteriorated. When the amount is more than 50 parts by weight, it is difficult to secure hardness characteristics due to the presence of unreacted functional groups due to the steric hindrance effect.

Photopolymerization  The compound (B)

The photopolymerizable compound (B) of the present invention is a component for improving the mechanical properties (in particular, hardness) of the hard coat layer.

The type of the photopolymerizable compound (B) is not particularly limited, and for example, it may be a monofunctional compound having a polymerizable unsaturated group or a polyfunctional compound, and these may be used alone or in combination of two or more.

A compound having 1 to 3 polymerizable unsaturated groups in the molecule can improve the curing property of the cured product without decreasing the crosslinking density at the time of curing and a polyfunctional compound having 4 or more polymerizable unsaturated groups in the molecule can exhibit a crosslinking density So that it is possible to realize an excellent hardness in the hard coat layer.

As specific examples of the photopolymerizable compound of the present invention, it is possible to use, as a monomer containing at least one (meth) acrylate functional group as a polymerizable functional group, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) (Meta) acrylate, ether (meth) acrylate, urethane (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (Meth) acrylate and epoxy (meth) acrylate, and melamine (meth) acrylate.

As the polymerizable unsaturated group, a compound having a (meth) acryloyl group or a vinyl group is preferable, and specific examples include (meth) acrylic acid ester, N-vinyl compound, vinyl-substituted aromatic compound, vinyl ether and vinyl ester have.

(Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, glycerol tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (Meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol (meth) acrylate, 1,3-butanediol di Acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di 2-hydroxyethyl) isocyanurate di (meth) acrylate, ethylene oxide or propylene oxide-added poly (meth) acrylate in the (meth) acrylic acid ester; (Meth) acrylate, oligoether (meth) acrylate, oligourethane (meth) acrylate, oligoepoxy (meth) acrylate having 1 to 3 (meth) acryloyl groups in the molecule; Hydroxypropyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, ethylene oxide or propylene oxide addition product to the above (meth) acrylic acid ester; Acrylates such as mono (meth) acrylic acid ester, iso-octyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) Rate can be provided. As the N-vinyl compound, N-vinyl pyrrolidone, N-vinyl caprolactam, N-vinyl phthalimide, N-vinyl succinimido and the like may be provided. Examples of the vinyl-substituted aromatic compound include styrene, divinylbenzene, chloromethylstyrene, hydroxystyrene, alpha-methylstyrene, bromomethylstyrene, and tribromomethylstyrene. As the vinyl ether, diethylene glycol monomethyl vinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether and the like may be provided. As the vinyl ester, vinyl acetate, vinyl propionate, vinyl benzoate and the like may be provided.

In the photopolymerizable compound, urethane (meth) acrylate is preferably used in view of hardness improvement, and (meth) acrylate containing an oxyethylene group is preferably used from the viewpoint of improving flexibility. Most preferably, (meth) acrylate containing an urethane group-containing (meth) acrylate and an oxyethylene group is used together.

In the present invention, the urethane-based acrylate can be prepared by condensation reaction of a diisocyanate compound and a polyfunctional (meth) acrylate compound having a hydroxy group.

The kind of the diisocyanate compound is not particularly limited, but may be a compound substituted with a cyclohexyl group, whereby the urethane acrylate may have a substituent of a cyclohexyl group. In this case, the cyclohexyl group is preferred because it has both hardness and flexibility due to the structural stability of the cyclohexyl group.

Specific examples of the diisocyanate compound substituted with a cyclohexyl group include, but are not limited to, 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, and 4,4-decylclohexyl methane diisocyanate, Specific examples thereof include the compounds represented by the following formulas (2) and (3).

(2)

(3)

Specific examples of the polyfunctional acrylate having a hydroxyl group include trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and the like, no.

In the present invention, the acrylate containing an oxyethylene group may be prepared by subjecting a polyhydric alcohol to an addition reaction with ethylene oxide to obtain a polyfunctional alcohol having an oxyethylene group and then subjecting the polyfunctional alcohol to a condensation reaction with (meth) acrylic acid Specific examples of polyhydric alcohols include, but are not limited to, glycerol, trimethylpropane, pentaerythritol, dipentaerythritol and the like.

Specific examples of the acrylate containing an oxyethylene group include 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 (meta 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. However, the present invention is not limited thereto, and specific examples thereof include compounds represented by the following formulas .

[Chemical Formula 4]

[Chemical Formula 5]

In the present invention, the content of the photopolymerizable compound (B) is not particularly limited. For example, the content of the photopolymerizable compound (B) is in the range of 65 to 95 parts by weight based on 100 parts by weight of the polymerizable components (mixed weight of (A) And preferably from 60 to 80 parts by weight. When the above range is satisfied, excellent mechanical properties can be secured.

In the present invention, when the photopolymerizable compound (B) according to the present invention is used in combination with acrylate containing urethane (meth) acrylate and oxyethylene group, the content of urethane-based acrylate is not particularly limited, May be included in an amount of 20 to 70 parts by weight, preferably 40 to 50 parts by weight, based on 100 parts by weight of the total of (A) and (B). When the above range is satisfied, excellent mechanical properties can be secured. When the amount is less than 20 parts by weight, the hardness may be lowered, and when it is more than 70 parts by weight, the shrinkage force may excessively increase, and curling, breaking, cracking, etc. of the coating layer may occur.

The content of the oxyethylene group-containing (meth) acrylate is not particularly limited. For example, the content of the polymerizable component (A) and (B) By weight, preferably 30 to 40 parts by weight. When the above range is satisfied, excellent mechanical properties can be secured and flexibility can be realized. If the amount is less than 10 parts by weight, the mechanical properties may deteriorate due to the decrease in the curing density. If the amount is more than 50 parts by weight, it may be difficult to secure flexibility due to the increase in the curing density.

Light curing Initiator (C)

The photopolymerization initiator (C) according to the present invention is not particularly limited as long as it can form radicals by light irradiation.

The photopolymerization initiator (C) is a hydrogen type recycling type Type 2 initiator coexisting with a Type 1 initiator and a tertiary amine in which radicals are generated by decomposition of a molecule due to a difference in chemical structure or molecular binding energy.

Specific examples of the Type 1 initiator include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone, diethoxyacetophenone, 2-hydroxy- 2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone and the like, benzoin, benzoin methyl Benzoin ethers such as benzoin ethyl ether and benzyl dimethyl ketal, acylphosphine oxides and titanocene compounds.

Specific examples of the Type 2 type initiator include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'- Methyl-4-methoxybenzophenone, benzophenones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone and isopropylthioxanthone, Ton.

The photopolymerization initiator may be used alone or in combination of two or more. Type 1 and Type 2 may be used alone or in combination.

Commercially available photopolymerization initiators include Irgacure 184 (BASF).

In the present invention, the content of the photopolymerization initiator (C) is not particularly limited and may be, for example, 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the total composition . When the above range is satisfied, excellent mechanical properties and adhesion can be realized. If the amount is less than 0.1 part by weight, the curing may not proceed sufficiently, and the mechanical properties and adhesion of the final coating film may be deteriorated. If the amount exceeds 10 parts by weight, cracks and curl due to curing shrinkage may occur.

The solvent (D)

The solvent (D) according to the present invention can be used without particular limitation as long as it can dissolve or disperse the above components.

Specific examples thereof include alcohols (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol and the like), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl 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 , Xylene, etc.). These may be used singly or in combination of two or more.

In the present invention, the content of the solvent is not particularly limited, but may be, for example, 5 to 90 parts by weight, preferably 20 to 70 parts by weight based on 100 parts by weight of the total composition. When it is included in the above-mentioned content range, appropriate coating property can be realized, which is preferable. On the other hand, when the amount is less than 5 parts by weight, the coating property is deteriorated due to the high viscosity. When the amount is more than 90 parts by weight, the thickness of the coating film is difficult to adjust and drying unevenness may occur.

Inorganic nanoparticles (E)

The composition for forming a hard coating according to the present invention may further comprise inorganic nanoparticles (E) to ensure mechanical properties of the hard coating layer.

The inorganic nanoparticles (E) can be uniformly formed in the coating film to improve mechanical properties such as abrasion resistance, scratch resistance and pencil hardness.

The average particle diameter of the inorganic nanoparticles (D) according to the present invention is not particularly limited, but may be, for example, 1 to 100 nm, preferably 5 to 50 nm. And excellent mechanical characteristics can be realized within the above range. On the other hand, when the average particle size is less than 1 nm, aggregation of particles occurs and a uniform coating film can not be formed. When the average particle size exceeds 100 nm, not only optical properties but also mechanical properties are lowered.

The kind of the inorganic nanoparticles (D) is not particularly limited and may be, for example, a metal oxide, and may be 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 a combination thereof, preferably Al ₂ O ₃ , SiO ₂ , ZrO ₂ can be used.

In the present invention, the content of the inorganic nanoparticles (D) is not particularly limited, but may be, for example, 10 to 50 parts by weight based on 100 parts by weight of the total composition. When it is included in the above content range, it has excellent mechanical properties such as abrasion resistance, scratch resistance and pencil hardness. On the other hand, if it exceeds 50 parts by weight, the curability may be deteriorated and the mechanical properties may be deteriorated, and the appearance may be poor.

The inorganic nanoparticles may be diluted to an organic solvent at a concentration of 10 to 80% by weight.

Additive (F)

The composition for forming a hard coating according to the present invention may further contain additives as needed in addition to the above-mentioned components, for example, a leveling agent, a UV stabilizer, and a heat stabilizer.

The leveling agent is added to improve the smoothness and coatability of the coating film when applying the composition, and a silicone leveling agent, a fluorine leveling agent, an acrylic leveling agent, and the like can be used. BYK-373, BYK-375, BYK-377, BYK-378, TEGO Glide 410 from Daegu, 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, FC-4430 and FC-4432 manufactured by 3M Co., Ltd. can be used.

The ultraviolet screening agent is added to prevent the surface of the coating film from being discolored or shattered by continuous ultraviolet ray exposure, and acts to block or absorb ultraviolet rays. The ultraviolet stabilizer may be classified into absorbents, quenchers, and Hindered Amine Light Stabilizers (HALS) according to the mechanism of action, for example, phenyl salicylates, Benzophenone (absorbent), benzotriazole (absorbent), nickel derivative (quencher), and radical scavenger.

As the thermal stabilizer, polyphenol-based, phosphite-based, and lactone-based heat stabilizers can be used. The ultraviolet stabilizer and the heat stabilizer can be mixed in appropriate amounts at a level that does not affect the ultraviolet hardening property.

The additives are preferably used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the total composition.

&Lt; Optical film &

The present invention also provides an optical film having a hard coat layer formed from the composition for forming a hard coat layer.

The optical film of the present invention comprises a base film having a hard coating layer formed on the at least one side thereof with the above composition.

The base film can be used without any particular limitation as long as it is a transparent polymer film. Examples of the base film include triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, , Polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, poly For example, a film formed of polymers such as ether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate and the like. These polymers may be used alone or in combination of two or more.

In the case of a crystalline polymer base material film, an engineering plastic base material, or a polymer base film whose surface becomes hydrophilic due to hydrolysis or saponification, which is difficult to impart adhesion force after coating in the base film, it is difficult to increase adhesion when using a composition for forming a conventional hard coating layer, The mechanical properties may deteriorate. However, the above-mentioned composition for forming a hard coat layer of the present invention can achieve excellent adhesion without deteriorating the mechanical properties of these base film.

The base film may be subjected to a surface treatment such as a plasma treatment or a corona treatment in order to improve adhesion with the hard coat layer.

The hard coating layer is formed by applying a composition for forming a hard coating layer on a base film and curing the coating. The coating may be performed by a slit coating method, a knife coating method, a spin coating method, a casting method, a microgravure coating method, A roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a gravure printing method, a flexo printing method, an offset printing method, an inkjet coating method, a dispenser printing method, Can be used.

The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 占 퐉. When the thickness is within the above range, excellent hardness and flexibility are exhibited, and the curling phenomenon can be prevented.

Since the optical film of the present invention has excellent hardness, flexibility and curling characteristics, it can be advantageously applied to a window film of an image display device.

<Image Display Device>

The present invention also provides an image display apparatus having the hard coating film.

The hard coating film of the present invention is excellent in hardness and flexibility, so that the hard coating film can be used, for example, as an outermost window film of an image display apparatus, and is particularly applicable to a flexible image display apparatus.

The image display device may be any of various image display devices such as a liquid crystal display device, an electroluminescence display device, a plasma display device, a field emission display device, and the like.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Manufacturing example  - Polymerizable  ingredient

division
(Parts by weight) Dendrimer compound Photopolymerizable compound Kinds content Urethane-based Oxyethylene series Other content Production Example 1 A-1 25 B-1 B'-1 - 40/35/0 Production Example 2 A-1 25 B-2 B'-1 - 40/35/0 Production Example 3 A-1 20 B-1 B'-2 - 40/40/0 Production Example 4 A-1 30 B-2 B'-2 - 40/40/0 Production Example 5 A-1 30 B-1 B'-2 - 60/10/0 Production Example 6 A-1 30 B-2 B'-2 - 60/10/0 Production Example 7 A-1 30 B-1 / B-3 B'-2 - 10/40/20/0 Production Example 8 A-1 30 B-2 B'-2 - 60/10/0 Production Example 9 A-2 25 B-1 B'-1 - 40/35/0 Production Example 10 A-2 18 B-1 B'-1 - 48/35/0 Production Example 11 A-2 45 B-1 B'-1 - 35/30/0 Production Example 12 A-2 55 B-1 B'-1 - 30/15/0 Production Example 13 A-1 25 - - B "-1 0/0/75 Production Example 14 A-1 25 - - B "-2 0/0/75 Production Example 15 - B-3 B'-1 - 50/50/0 Production Example 16 - - B'-1 B "-3 0/50/50 Production Example 17 - B-2 B'-2 - 60/40/0 Production Example 18 - - B'-1 / B'-2 - 0/60/40

A-1: Third generation dendrimer compound

A-2: Second generation dendrimer compound

B-1: Shin-A T & C SOU-1700B

B-2: Shin-A T & C SOU-1290

B-3: UA-306H (Public Corporation)

B'-1: M4004 (Mi Won Specialty Chemical)

B'-2: DPEA126 (Japanese explosive)

B "-1: M300 trimethylolpropane triacrylate (trade name: SPS)

B "-2: M600 dipentaerythritol hexaacrylate (trade name: SPS)

B "-3:

M-340 (Miwon Specialty Chemical)

Example  And Comparative Example

30 parts by weight of a mixture of the polymerizable components (used in Examples 1 to 14 (used in Production Examples 1 to 14) and Comparative Examples 1 to 4 (used in Production Examples 15 to 18) , 30 parts by weight of a photoinitiator igacure 184 (BASF Corp.), 3 parts by weight of a leveling agent BYK-333, 30 parts by weight of methyl ethyl ketone and 10 parts by weight of toluene, A composition for forming a hard coating was prepared.

Test Methods

The compositions for hard coating formation of the examples and comparative examples were coated on an 80 μm optical polyimide film (Mitsubishi Gas Chemical Co., 100 μm, L-3430) using a bar coater, dried and coated to a thickness of 20 μm Lt; 0 &gt; C for 2 minutes, and irradiated with a high pressure mercury lamp at 350 mJ / cm &lt; ² &gt; to produce a hardcoat film.

(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 a product of Mitsubishi and was subjected to an experiment five times per pencil hardness so that the maximum pencil hardness at which scratches were less than or equal to one time was expressed as the pencil hardness of the hard coating layer.

(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., Ltd.).

Steel wool used # 0000.

<Evaluation Criteria>

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 side 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.

Adhesion = n / 100

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

100: total number of squares

Therefore, when one of them was not peeled off, it was recorded as 100/100.

(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) Mandrell

In order to evaluate the flexibility and crackability of the coating film, a coated film sample cut into a size of 1 cm × 10 cm was placed on a steel rod of each diameter (2φ~10 φ), and the coating layer was folded by hand with the coating layer raised, The smallest diameter is indicated.

division Pencil hardness Abrasion resistance Adhesiveness curl Mandrell Example 1 6H S 100/100 3mm 2φ Example 2 5H S 100/100 3mm 2φ Example 3 6H S 100/100 3mm 3φ Example 4 5H S 100/100 3mm 3φ Example 5 5H S 100/100 4mm 3φ Example 6 5H S 100/100 5mm 2φ Example 7 5H S 100/100 3mm 3φ Example 8 6H A 100/100 4mm 3φ Example 9 5H A 100/100 6mm 5φ Example 10 4H A 100/100 6mm 5φ Example 11 4H A 100/100 5mm 5φ Example 12 3H A 100/100 7mm 6φ Example 13 4H A 100/100 5mm 4φ Example 14 4H A 100/100 5mm 4φ Comparative Example 1 HB A 97/100 15mm 15φ Comparative Example 2 F A 98/100 12mm 12φ Comparative Example 3 H A 97/100 10mm 9φ Comparative Example 4 F A 98/100 12mm 12φ

Referring to Table 2, it was confirmed that all the optical films formed from the composition for forming a hard coating according to the present invention exhibited excellent pencil hardness and flexibility.

However, the comparative examples not using the dendrimer compound according to the present invention can not secure both hardness and flexibility, and thus it is confirmed that they are not suitable for a window substrate of a flexible display.

Claims (10)

A composition for forming a hard coating, which comprises a dendrimer compound (A) represented by the following formula (1), a photopolymerizable compound (B), a photopolymerization initiator (C) and a solvent (D)
[Chemical Formula 1]
(R ₁ ) _{4- n} C (CH ₂ OR ₂ ) _n
(Wherein n is an integer of 2 to 4,
R ₁ is an alkyl group having 2 to 5 carbon atoms,
R ₂ is

ego,
m is 2 or 3,
R ₃ is a hydrogen atom or a (meth) acrylate group, and at least one R ₃ in the molecule is a (meth) acrylate group.
[2] The method according to claim 1,
R ₃ is a hydrogen atom or

And at least one R &lt; ₃ &gt;

Lt;
X is 2 or 3,
R ₄ is a hydrogen atom or a (meth) acrylate group, and at least one R ₄ in the molecule is a (meth) acrylate group.
The dendrimer compound (A) according to claim 1, wherein the dendrimer compound (A) is contained in an amount of 10 to 50 parts by weight per 100 parts by weight of the total of the polymerizable components (A) and (B) / RTI &gt;
The composition for forming a hard coating according to claim 1, wherein the photopolymerizable compound (B) comprises at least one member selected from the group consisting of urethane-based (meth) acrylate and (meth) acrylate containing an oxyethylene group.
The composition for forming a hard coating according to claim 4, wherein the urethane (meth) acrylate is substituted with a cyclohexyl group.
The composition for forming a hard coating according to claim 1, wherein the photopolymerization initiator (C) is at least one selected from the group consisting of an acetophenone photoinitiator and an amino ketone photoinitiator.
The composition for forming a hard coating according to claim 1, further comprising inorganic nanoparticles.
An optical film comprising a coating film formed on at least one surface of a base film of the composition for forming a hard coating according to any one of claims 1 to 7.
The optical film according to claim 8, wherein the optical film is a window film.
An image display device comprising the optical film of claim 8.