KR20170045504A - Composition for forming hard coating - Google Patents

Abstract

The present invention relates to a composition for forming a hard coating and more specifically, to a composition for forming a hard coating which shows high hardness and excellent flexibility at the same time and thus may be applied advantageously to forming a hard coating layer for flexible displays, wherein the composition comprises (A) a cyclic phosphazene dendrimer compound having a terminal (meth)acrylate group, (B) a urethane-based (meth)acrylate resin and (C) a (meth)acrylate having an oxyethylene group.

Description

COMPOSITION FOR FORMING HARD COATING [0002]

The present invention relates to compositions for forming hard coatings.

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 process for producing a hard film comprising a dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branching end, a urethane (meth) acrylate resin (B) and a (meth) Composition for forming a coating.

2. The composition for forming a hard coating according to 1 above, wherein the phosphazene compound is represented by the following formula (1):

[Chemical Formula 1]

(Wherein R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a structure represented by the following formula (2), wherein at least one of R is a structure represented by the following formula (2)

 (2)

이며, R₂는 직접 결합 또는 탄소수 1 내지 6의 알킬렌기이고, R₃는 수소 원자 또는 메틸기임).(In the formula, * ₁ and doedoe independently a repeating unit structure is 0-3 times with each other in * _2, * ₁ and * ₂ are in the repeating unit of the above structure, once at least one, and ends

R ₂ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₃ is a hydrogen atom or a methyl group).

3. The composition for forming a hard coating according to 1 above, wherein the phosphazene compound is contained in an amount of 5 to 35 parts by weight based on 100 parts by weight of the total of the polymerizable components (A), (B) and (C).

(Meth) acrylate containing 20 to 70 parts by weight of a urethane-based acrylate (B) based on 100 parts by weight of the polymerizable components (A), (B) and (C) And 10 to 50 parts by weight of an acrylate (C).

5. The composition for forming a hard coating according to item 1, further comprising at least one photopolymerization initiator (D) selected from the group consisting of an acetophenone photoinitiator and an amino ketone photoinitiator.

6. The composition for hard coating formation according to item 1, further comprising inorganic nanoparticles (F).

7. An optical film comprising, on at least one surface of a base film, a coating layer formed of the composition for forming a hard coating as described in any one of the above 1 to 6.

8. The optical film according to 7 above, wherein the optical film is a window film.

9. An image display device comprising the optical film of 7 above.

The composition for forming a hard coating of the present invention can form a hard coating layer having high hardness.

In addition, the composition for forming a hard coating of the present invention can form a hard coating layer having excellent curl characteristics and flexibility.

Thus, the composition for forming a hard coating of the present invention simultaneously exhibits high hardness and excellent flexibility, and can be preferably applied to form a hard coating layer for a flexible display.

The present invention comprises a dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal, a urethane (meth) acrylate resin (B) and a (meth) acrylate Also exhibits excellent flexibility, and relates to a composition for forming a hard coating, which can be suitably applied to the formation of a hard coating layer for a flexible display.

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 cyclic phosphazene compound (A) having a (meth) acrylate group at the branching end, a urethane (meth) acrylate resin (B) and a (meth) acrylate having an oxyethylene group ).

At the end of the branch ( Meta ) Acrylate group  Have Dendrimer  Annular Phosphazene  The compound (A)

The dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal according to the present invention has a role of significantly improving the flexibility and hardness of the hard coat layer.

A dendrimer is a polymer that repeatedly stretches from a core to a twisted unit structure. The step of growing a dendrimer is called a 'generation', and a generation increases every time a constant repeating unit structure is added .

The dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal according to the present invention has a cyclic phosphazene core structure, and the (meth) acrylate group is present at the branch terminus, And the polymeric compound.

The dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branched end according to the present invention has a significantly larger number of functional groups than the molecular weight, and can increase the curing density. In addition, a tertiary amine having a phosphazene structure can induce a dehydrogenation reaction during the photo-curing reaction to improve the curing density and exhibit an excellent hardness due to the inorganic cyclic structure itself. Thus, the hardness and mechanical properties of the hard coat layer can be remarkably improved.

Further, since the center is empty and the polymerization reaction is carried out at the branched end, a hard coat layer having excellent flexibility can be obtained.

The dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal according to the present invention has a ring of 6 to 12, preferably 6, and may be represented by, for example, the following formula .

[Chemical Formula 1]

(Wherein R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a structure represented by the following formula (2), wherein at least one of R is a structure represented by the following formula (2)

 (2)

이며, R₂는 직접 결합 또는 탄소수 1 내지 6의 알킬렌기이고, R₃는 수소 원자 또는 메틸기임).(In the formula, * ₁ and doedoe independently a repeating unit structure is 0-3 times with each other in * _2, * ₁ and * ₂ are in the repeating unit of the above structure, once at least one, and ends

R ₂ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₃ is a hydrogen atom or a methyl group).

At least one of Rs represented by the general formula (1) has a structure represented by the general formula (2). In view of further improving the hardness by containing a larger number of functional groups, R of three or more structural units may have a structure represented by the general formula , More preferably all R's may have the structure of formula (2).

In the above formula (2), the number of generations increases according to the number of repeats of the unit structure, and the unit structure is repeated one to three times in at least one of * ₁ and * ₂ . If the number of repeats is more than 3, an unreacted (meth) acrylic group remains due to excessive steric hindrance, and the photocuring conversion rate may be reduced. From the standpoint of maximizing the photo-curing conversion ratio to exhibit excellent hardness and at the same time exhibiting excellent flexibility, the number of repeating units may preferably be 1 or 2.

The content of the dendritic cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal according to the present invention is not particularly limited, and the content of the polymerizable component (A) containing (A), (B) 5 to 35 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the resin composition. If the content is less than 5 parts by weight, it may be difficult to realize an excellent hardness. If the content is more than 30 parts by weight, the hardness may excessively increase and the flexibility may be deteriorated.

In the present specification, the polymerizable component is a component containing a dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branched end and a photopolymerizable compound described below. Specifically, a dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminal, a urethane (meth) acrylate (B), a (meth) acrylate (C) containing an oxyethylene group, Further comprising a known photopolymerizable compound which may be included, wherein these components are present as components that are each independently in the composition.

Photopolymerization  compound

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

The composition for forming a hard coating of the present invention comprises a urethane (meth) acrylate (B) in the light of hardness improvement and a (meth) acrylate (C) containing an oxyethylene group in terms of flexibility improvement as a photopolymerizable compound.

In the present invention, the urethane-based (meth) acrylate (B) can be prepared by condensation reaction of a diisocyanate compound with 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 of its structural stability and securing both hardness and flexibility.

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

(3)

[Chemical Formula 4]

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 (meth) acrylate (C) 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 oxyethylene group, and then adding (meth) acrylic acid . Specific examples of the polyhydric alcohol include, but are not limited to, glycerol, trimethylpropane, pentaerythritol, dipentaerythritol, and the like.

Specific examples of the (meth) acrylate (C) containing an oxyethylene group include trimethylolpropane (EO) ₃ tri (meth) acrylate, trimethylolpropane (EO) ₆ tri (meth) acrylate, 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, But are not limited to, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate, dipentaerythritol (EO) ₁₈ hexa (meth) acrylate and the like. Specifically, Compounds and the like have.

[Chemical Formula 5]

[Chemical Formula 6]

The content of the urethane-based acrylate (B) is not particularly limited and may be, for example, 20 to 70 parts by weight based on 100 parts by weight of the polymerizable components (A), (B) and (C) , Preferably 30 to 60 parts by weight. 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 (C) is not particularly limited. For example, the total amount of the polymerizable components (A), (B) and (C) May be contained in an amount of 10 to 50 parts 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.

If necessary, the composition for forming a hard coating of the present invention may further comprise a photopolymerizable compound known in the art in addition to the (meth) acrylate (C) containing the urethane-based acrylate (B) and the oxyethylene group. (Meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol tetra (metha) acrylate, and pentaerythritol tetra (metha) acrylate as a monomer having at least one (meth) acrylate functional group as a polymerizable functional group. (Meth) acrylate, ether (meth) acrylate, and epoxy (meth) acrylate, melamine (meth) acrylate, ditrimethylolpropane tetra Methacrylate.

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.

The photopolymerizable compound which may be further included may be included in an amount of not more than 25 parts by weight based on 100 parts by weight of the total of the polymerizable components including (A), (B) and (C), but is not limited thereto.

Light curing Initiator (D)

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

The photopolymerization initiator (D) is 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 recycling type Type 2 initiator coexisting with a tertiary amine.

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 initiator include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzyl-4'-methyldiphenylsulfide, 3,3 ' Methyl-4-methoxybenzophenone and the like, benzophenones such as thioxanthone, 2-chromothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone and isopropylthioxanthone Oxanone, and the like.

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 (D) is not particularly limited, but 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.

Solvent (E)

The solvent (E) 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 (E) 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 (F)

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

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

The average particle diameter of the inorganic nanoparticles (F) 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 inorganic nanoparticles (F) are not particularly limited, and may be, for example, metal oxides. The inorganic nanoparticles (F) 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 (F) 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 (G)

The composition for forming a hard coating according to the present invention may further contain an additive (G), if necessary, 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 additive (G) is 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 comprising 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

The components and the contents (parts by weight) of the polymerizable components shown in Table 1 below were prepared.

division Phosphazene compound Photopolymerizable compound ingredient content Urethane-based Oxyethylene series Other content Production Example 1 A-1 / A-2 20/10 B-2 / B-3 B'-1 - 30/10/30 Production Example 2 A-1 / A-2 5/25 B-2 B'-1 B "-1 20/30/20 Production Example 3 A-1 / A-2 15/5 B-1 / B-3 B'-1 / B'-2 B "-1 40/10/10/10 Production Example 4 A-1 / A-2 5/15 B-2 / B-3 B'-2 - 20/20/40 Production Example 5 A-1 / A-2 10/10 B-1 B'-1 / B'-2 - 50/20/10 Production Example 6 A-1 / A-2 15/5 B-2 / B-3 B'-2 - 50/20/10 Production Example 7 A-1 / A-2 5/15 B-1 / B-3 B'-1 / B'-2 B "-1 10/30/10/2010 Production Example 8 A-1 / A-2 15/5 B-2 / B-3 B'-1 / B'-2 - 40/10/10/20 Production Example 9 A-1 20 B-2 / B-3 B'-2 - 20/20/40 Production Example 10 A-2 20 B-2 / B-3 B'-1 / B'-2 - 40/10/10/20 Production Example 11 A-1 / A-2 20/18 B-2 / B-3 B'-1 - 25/12/25 Production Example 12 - - B-3 B'-1 / B'-2 B "-1 30/30/10/30 Production Example 13 - - B-3 B'-1 B "-1 20/30/50 Production Example 14 - - B-2 / B-3 B'-2 - 40/20/40 Production Example 15 - - B-3 B'-1 / B'-2 - 30/30/40 Production Example 16 A-3 20 B-2 / B-3 B'-2 - 20/20/40

A-2:

A-3: IDEMITSU PPZ (오사카 유기화학사)
B-1: 신아 T&C SOU-1700B

B-2: 신아 T&C SOU-1290

B-3: UA-306H (공영사)

A-1:

A-2:

A-3: IDEMITSU PPZ (Osaka Organic Chemical Company)
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: M-340 (Wis. Specialty Chemicals)

Example  And Comparative Example

30 parts by weight of Nanopol 784 (Ebonic, PGEMA 50% diluted 20 nm silica sol), 5 parts by weight of photoinitiator igacure 184 (BASF Corp.), 30 parts by weight of a leveling agent 3 parts by weight of BYK-333, 30 parts by weight of methyl ethyl ketone, and 10 parts by weight of toluene were added to the mixture of Examples 1 to 11 (using Production Examples 1 to 11) and Comparative Examples 1 to 5 (using Production Examples 12 to 16) A composition for forming a hard coating was prepared.

Experimental Example

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.).

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. Adhesiveness

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 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Pencil hardness 6H 6H 6H 6H 6H 5H 6H 6H 5H 5H 7H Abrasion resistance S S S S S S S A A A A Adhesiveness 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 95/100 96/100 90/100 curl 4mm 4mm 4mm 5mm 5mm 5mm 6mm 5mm 7mm 7mm 10mm Mandrell 3φ 3φ 3φ 3φ 4φ 3φ 4φ 4φ 5φ 5φ 6φ

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Pencil hardness F F F HB H Abrasion resistance C C C C C Adhesiveness 65/100 65/100 72/100 70/100 70/100 curl 14mm 13mm 14mm 12mm 12 mm Mandrell 8φ 8φ 10φ 10φ 9φ

Referring to Tables 2 and 3, it was confirmed that the optical films formed from the composition for forming a hard coating according to the present invention exhibited excellent pencil hardness and flexibility.

However, it can be confirmed that the comparative examples do not have both hardness and flexibility at the same time and are not suitable for a window substrate of a flexible display.

Claims (9)

(C) having a dendrimer cyclic phosphazene compound (A) having a (meth) acrylate group at the branch terminus, a urethane (meth) acrylate resin (B) and an oxyethylene group .
The composition for forming a hard coating according to claim 1, wherein the phosphazene compound is represented by the following formula (1)
[Chemical Formula 1]

(Wherein R is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a structure represented by the following formula (2), wherein at least one of R is a structure represented by the following formula (2)
(2)

(In the formula, * ₁ and doedoe independently a repeating unit structure is 0-3 times with each other in * _2, * ₁ and * ₂ are in the repeating unit of the above structure, once at least one, and ends

R ₂ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₃ is a hydrogen atom or a methyl group).
The composition for forming a hard coating according to claim 1, which comprises 5 to 35 parts by weight of a phosphazene compound based on 100 parts by weight of the total of the polymerizable components (A), (B) and (C).
The thermoplastic resin composition according to claim 1, which comprises 20 to 70 parts by weight of urethane-based acrylate, 10 to 50 parts by weight of (meth) acrylate containing an oxyethylene group per 100 parts by weight of the total of the polymerizable components (A), (B) By weight based on the total weight of the composition.
The composition for forming a hard coating according to claim 1, further comprising at least one photopolymerization initiator (D) 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 (F).
An optical film comprising a coating layer formed on at least one side of a base film of the composition for forming a hard coating according to any one of claims 1 to 6.
The optical film according to claim 7, wherein the optical film is a window film.
An image display device comprising the optical film of claim 7.