KR102375701B1 - Composition for forming hard coating - Google Patents

Abstract

The present invention relates to a composition for forming a hard coating, and more particularly, to a dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branching end; and a polymerizable compound (B) comprising a urethane-based (meth)acrylate resin and (meth)acrylate having an oxyethylene group; thereby exhibiting high hardness and excellent flexibility at the same time, preferably for forming a hard coating layer for a flexible display It relates to a composition for forming a hard coating that can be applied.

Description

Composition for forming a hard coating {COMPOSITION FOR FORMING HARD COATING}

The present invention relates to a composition for forming a hard coating.

Recently, a thin display device using a flat panel display such as a liquid crystal display or an organic light emitting diode display has received great attention. In particular, these thin display devices are implemented in the form of a touch screen panel, and are characterized by portability to various wearable devices as well as smart phones and tablet PCs. It is widely used in various smart devices.

These portable touch screen panel-based display devices have a window film for display protection on the display panel to protect the display panel from scratches or external impact, and in most cases, tempered glass for display is used as the window film. Tempered glass for display is thinner than general glass, but it has high strength and is strong against scratches.

However, tempered glass has the disadvantage that it is not suitable for reducing the weight of portable devices due to its heavy weight, and it is difficult to implement unbreakable properties because it is vulnerable to external shocks, and it is not bent beyond a certain level and is bendable. It is not suitable as a flexible display material having a foldable function.

In recent years, various studies have been conducted on optical plastic covers having strength or scratch resistance corresponding to tempered glass while securing flexibility and impact resistance. In general, as for the optical transparent plastic cover material, which has more flexibility than tempered glass, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyacrylate (PAR), polycarbonate (PC) , polyimide (PI), and the like. However, in the case of these polymer plastic substrates, compared to tempered glass used as a window film for display protection, not only exhibit insufficient physical properties in terms of hardness and scratch resistance, but also insufficient impact resistance. Therefore, various attempts are being made to supplement the physical properties required by coating the composite resin composition on these plastic substrates.

Accordingly, high hardness was secured by forming a hard coating on the plastic substrate film. In the case of a general hard coating, a composition consisting of a resin containing a photocurable functional group, a curing agent or a curing catalyst and other additives is used. In the case of the composite resin, it can be used as a display protection window with improved hardness and scratch resistance by coating it on an optical plastic base film.

However, in the case of a general photo-curable composite resin, it is difficult to realize high hardness corresponding to tempered glass, and curl phenomenon due to shrinkage occurs greatly during curing, and flexibility is not sufficient. There is a disadvantage that it is not suitable as a protective window film.

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

Korea Patent Publication No. 2013-74167

An object of the present invention is to provide a composition for forming a hard coating capable of simultaneously implementing high hardness and flexibility and producing a hard coating film with suppressed curl.

In addition, an object of the present invention is to provide an optical film having a hard coat layer formed of the composition for forming a hard coat.

Moreover, an object of this invention is to provide the image display apparatus provided with the said optical film.

1. A dendrimer polyhedral oligomeric silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal; And a urethane-based (meth) acrylate resin and a polymerizable compound (B) comprising (meth) acrylate having an oxyethylene group; A composition for forming a hard coating comprising a.

2. The composition for forming a hard coating according to the above 1, wherein the silsesquioxane compound is a dendrimer polyhedral oligomeric silsesquioxane compound having 6 to 12 structural units represented by the following Chemical Formula 1:

[Formula 1]

_{RSiO 1.5}

(Wherein, R is each 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 in each structural unit is a structure of the following formula (2))

[Formula 2]

(Wherein, R ₁ is an alkylene group having 1 to 6 carbon atoms, R ₂ , R ₃ and R ₄ are each independently a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₅ , R ₆ and R ₇ are each other independently a hydrogen atom or a methyl group, and n is an integer from 1 to 3).

3. The composition for forming a hard coating according to the above 2, wherein n is 1 or 2 in Formula 2 above.

4. The composition for forming a hard coating according to the above 1, comprising 5 to 35 parts by weight of the silsesquioxane compound based on 100 parts by weight of the total weight of the polymerizable component (mixed weight of (A) and (B)).

5. In 1 above, 20 to 70 parts by weight of a urethane-based acrylate, 10 to 50 parts by weight of a (meth)acrylate containing an oxyethylene group, based on 100 parts by weight of the polymerizable component (total weight of (A) and (B)) A composition for forming a hard coating comprising parts by weight.

6. The composition for forming a hard coating according to the above 1, further comprising at least one photopolymerization initiator (C) selected from the group consisting of an acetophenone-based photoinitiator and an aminoketone-based photoinitiator.

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

8. An optical film having a coating layer formed of the composition for forming a hard coating of any one of 1 to 7 above on at least one surface of the base film.

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

10. An image display device comprising the optical film of 8 above.

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

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

Accordingly, the composition for forming a hard coating of the present invention exhibits high hardness and excellent flexibility at the same time, and can be preferably applied to the formation of a hard coating layer for a flexible display.

The present invention relates to a dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal; and a polymerizable compound (B) comprising a urethane-based (meth)acrylate resin and (meth)acrylate having an oxyethylene group; thereby exhibiting high hardness and excellent flexibility at the same time, preferably for forming a hard coating layer for a flexible display It relates to a composition for forming a hard coating that can be applied.

Hereinafter, the present invention will be described in detail.

< hard coating Forming composition>

The composition for forming a hard coating of the present invention comprises: a dendrimer polyhedral oligomeric silsesquioxane compound (A) having a (meth)acrylate group at the branching end; and a polymerizable compound (B) containing (meth)acrylate having a urethane-based (meth)acrylate resin and an oxyethylene group.

(A) at the branch end ( meta ) acrylate group having dendrimer polyhedral oligomers Silsesquioxane compound

The dendrimer polyhedral oligomeric silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal according to the present invention plays a role in remarkably improving the flexibility and hardness of the hard coating layer.

A dendrimer is a polymer in which a certain unit structure in the shape of a tree branch repeatedly extends from the core, and the stage of dendrimer growth is called a 'generation'. indicates.

The dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branched end according to the present invention has a silica cage core structure, and a (meth)acrylate group exists at the branched end to form a hard coating composition It will perform the role of a polymerizable compound within.

The dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal has both properties of inorganic silica and organic silicone. Therefore, unlike general inorganic particles, even when a large amount is used, uniform mixing is possible in the composition, thereby remarkably improving hardness and mechanical properties.

In addition, since the center is empty and the polymerization reaction is performed at the branch ends, a hard coating layer having excellent flexibility can be obtained.

The dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal according to the present invention is a dendrimer compound of the second to fourth generations, for example, a structural unit represented by the following formula (1) 6 to It may be a dendrimer polyhedral oligomeric silsesquioxane compound having 12.

[Formula 1]

_{RSiO 1.5}

(Wherein, R is each 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 in each structural unit is a structure of the following formula (2))

[Formula 2]

(Wherein, R ₁ is an alkylene group having 1 to 6 carbon atoms, R ₂ , R ₃ and R ₄ are each independently a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₅ , R ₆ and R ₇ are each other independently a hydrogen atom or a methyl group, and n is an integer from 1 to 3).

Each structural unit represented by Formula 1 is connected to other structural units through a shared oxygen atom to form a cage-type structure.

At least one of R of each structural unit represented by Formula 1 has the structure of Formula 2, and preferably 4 or more structural units R is the structure of Formula 2 in terms of further improving hardness by including more functional groups may have, and more preferably, R of all structural units may have the structure of formula (2).

In Formula 2, the number of generations increases as n increases, and n is an integer of 1 to 3. If n is greater than 3, unreacted (meth)acrylate groups may remain due to excessive steric hindrance, thereby reducing the photocurable conversion rate. Preferably, n may be 1 or 2 in terms of exhibiting a high photocurable conversion rate to exhibit excellent hardness and at the same time excellent flexibility.

The content of the dendrimer polyhedral oligomeric silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal according to the present invention is not particularly limited, and for example, the polymerizable component (the total weight of (A) and (B)) It may be included in an amount of 5 to 35 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight in total. If the content is less than 5 parts by weight, it may be difficult to implement excellent hardness, and if it exceeds 35 parts by weight, the hardness may excessively increase and flexibility may be reduced.

photopolymerization Compound (B)

The photopolymerizable compound (B) according to the present invention is a component for improving the mechanical properties (particularly, hardness) of the hard coating layer.

The composition for forming a hard coating of the present invention includes a urethane-based (meth)acrylate in terms of improving hardness as a photopolymerizable compound (B), and (meth)acrylate including an oxyethylene group in terms of improving flexibility.

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

The type of the diisocyanate compound is not particularly limited, but may preferably be a compound substituted with a cyclohexyl group, and accordingly, the urethane acrylate may have a substituent of a cyclohexyl group. In this case, it is preferable in that hardness and flexibility can be secured at the same time 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, 4,4-disylchlorohexylmethane diisocyanate, and the like. Specifically, compounds represented by the following Chemical Formulas 3 and 4, etc. may be mentioned.

[Formula 3]

[Formula 4]

Specific examples of the polyfunctional acrylate having a hydroxyl group include, but are not limited to, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc. not.

In the present invention, the acrylate containing an oxyethylene group is prepared by adding ethylene oxide to a polyhydric alcohol to obtain a polyfunctional alcohol containing an oxyethylene group, and then condensing (meth)acrylic acid with the polyfunctional alcohol. Specific examples of the polyhydric alcohol include, but are not limited to, glycerol, trimethylpropane, pentaerythritol, dipentaerythritol, and the like.

Specific examples of the acrylate containing the oxyethylene group include trimethylolpropane (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, dipentaerythritol (EO) ₁₈ hexa (meth) acrylate and the like may be mentioned, but are not limited thereto, and specifically, compounds represented by the following Chemical Formulas 5 and 6, etc. may be mentioned. .

[Formula 5]

[Formula 6]

The content of the urethane-based acrylate is not particularly limited, but, for example, may be included in an amount of 20 to 70 parts by weight, preferably 30 to 100 parts by weight, based on a total of 100 parts by weight of the polymerizable component (the total weight of (A) and (B)). It may be included in an amount of from 60 parts by weight. When the above range is satisfied, excellent mechanical properties can be secured. If it is less than 20 parts by weight, the hardness may decrease, and if it exceeds 70 parts by weight, the shrinkage force may be excessively increased and curl, breakage, cracks, etc. of the coating layer may occur.

In addition, the content of the (meth)acrylate containing the oxyethylene group is not particularly limited, but for example, 10 to 50 parts by weight of the polymerizable components (total weight of (A) and (B)) based on 100 parts by weight in total. It may be included in 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 at the same time. If it is less than 10 parts by weight, mechanical properties may be deteriorated due to a decrease in the curing density, and if it exceeds 50 parts by weight, it may be difficult to secure flexibility due to an increase in the curing density.

If necessary, the composition for forming a hard coating of the present invention may further include a photopolymerizable compound known in the art in addition to the urethane-based acrylate and (meth)acrylate including an oxyethylene group. For example

As a monomer comprising at least one (meth)acrylate functional group as a polymerizable functional group, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol tetra (meth) acrylate , ditrimethylolpropane tetra (meth) acrylate, (meth) acrylate containing an oxyethylene group, ester (meth) acrylate, ether (meth) acrylate, and epoxy (meth) acrylate, melamine (meth) acrylic it is rate

A compound having a (meth)acryloyl group or a vinyl group as the polymerizable unsaturated group is preferable, and specific examples thereof include (meth)acrylic acid esters, N-vinyl compounds, vinyl-substituted aromatic compounds, vinyl ethers and vinyl esters. there is.

As (meth)acrylic acid ester, 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(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexane Diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, bis( 2-hydroxyethyl) isocyanurate di(meth)acrylate, poly(meth)acrylate in which ethylene oxide or propylene oxide is added to the (meth)acrylic acid ester; oligoester (meth)acrylate, oligoether (meth)acrylic acid ester, oligourethane (meth)acrylic acid ester, oligoepoxy (meth)acrylic acid ester having 1 to 3 (meth)acryloyl groups in the molecule; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and ethylene oxide or propylene oxide addition products to the (meth)acrylic acid ester; Mono (meth) acrylic acid ester, iso-octyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylic Rates may be provided. Further, as the N-vinyl compound, N-vinyl pyrrolidone, N-vinyl caprolactam, N-vinyl phthalimide, N-vinyl succinimido and the like may be provided. As the vinyl substituted aromatic compound, styrene, divinylbenzene, chloromethylstyrene, hydroxystyrene, alpha-methylstyrene, bromomethylstyrene, tribromomethylstyrene, and the like may be provided. As the vinyl ether, diethylene glycol monomethyl vinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether and the like can be provided. As the vinyl ester, vinyl acetate, vinyl propionate, vinyl benzoate and the like can be provided.

The photopolymerizable compound that may be additionally included may be included, for example, in an amount of 25 parts by weight or less based on 100 parts by weight of the polymerizable component (total weight of (A) and (B)), but is not limited thereto.

light curing initiator (C)

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

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

Specific examples of the Type 1 initiator include 4-phenoxydichloroacetphenone, 4-t-butyldichloroacetphenone, 4-t-butyltrichloroacetphenone, diethoxyacetphenone, 2-hydroxy-2-methyl-1 -Phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methyl Acetphenones such as propan-1-one, 4-(2-hydroxyethoxy)-phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoinmethyl Benzoins, such as ether, benzoin ethyl ether, and benzyl dimethyl ketal, acyl phosifine oxides, a titanocene compound, etc. are mentioned.

Specific examples of the Type 2 initiator include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzol-4'-methyldiphenylsulfide, 3,3' - Benzophenones such as methyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, and thioxanthone such as isopropylthioxanthone Oxanthone, etc. are mentioned.

A photoinitiator may use 1 type, and may use 2 or more types in parallel. In addition, Type 1 and Type 2 may be used alone or in combination.

Commercially available photopolymerization initiators include Igacure 184 (manufactured by BASF) and the like.

In the present invention, the content of the photopolymerization initiator (C) is not particularly limited, but, for example, may be included in an amount of 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 it is less than 0.1 parts by weight, curing may not proceed sufficiently, so that mechanical properties or adhesion of the final coating film may be reduced. If it exceeds 10 parts by weight, cracks and curls may occur due to curing shrinkage.

Solvent (D)

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

Specific examples include alcohols (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.); Acetate type (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellosolve type (methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.), hydrocarbon type (normal hexane, normal heptane, benzene, toluene) , xylene, etc.), and these may be used alone or in combination of two or more.

In the present invention, the content of the solvent (D) is not particularly limited, but, for example, may be included in an amount of 5 to 90 parts by weight, preferably 20 to 70 parts by weight, based on 100 parts by weight of the total composition. When included in the above content range, it is preferable to implement appropriate applicability. On the other hand, when it is less than 5 parts by weight, the viscosity is high and the applicability is lowered, and when it exceeds 90 parts by weight, it is difficult to adjust the thickness of the coating film, and drying unevenness may occur, resulting in poor appearance.

Inorganic nanoparticles (E)

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

The inorganic nanoparticles (E) may 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. Excellent mechanical properties can be implemented within the above range. On the other hand, when the average particle diameter is less than 1 nm, particle agglomeration occurs and a uniform coating film cannot be formed.

The type of the inorganic nanoparticles (D) is not particularly limited, but may be, for example, a metal oxide, Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , ITO, IZO, ATO, ZnO-Al, Nb ₂ O ₃ , SnO, MgO, and one selected from the group consisting of MgO and combinations thereof may be used, 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, for example, may be included in an amount of 10 to 50 parts by weight based on 100 parts by weight of the total composition. When included in the above content range, mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness are excellent. On the other hand, when it exceeds 50 parts by weight, the curability may be disturbed, and mechanical properties may be deteriorated, and the appearance may be deteriorated.

The inorganic nanoparticles may be used by diluting in an organic solvent to a concentration of 10 to 80% by weight.

Additive (F)

The composition for forming a hard coating according to the present invention may further include an additive (F) if necessary in addition to the above-described components, for example, a leveling agent, a UV stabilizer, a heat stabilizer, and the like.

The leveling agent is added to improve the smoothness and applicability of the coating film when the composition is applied, and a silicone leveling agent, a fluorine-based leveling agent, an acrylic-based leveling agent, and the like may be used. Commercial products of the leveling agent include BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378 by Chemi, TEGO Glide 410, TEGO Glide by Daegu. 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 3M's FC-4430, FC-4432, etc. can be used.

The sunscreen is added to prevent the surface of the coating film from being discolored or brittle by continuous exposure to ultraviolet rays, and serves to block or absorb ultraviolet rays. The ultraviolet stabilizer may be divided into absorbers, quenchers, and hindered amine light stabilizers (HALS) depending on the mechanism of action, for example, phenyl salicylate (Phenyl Salicylates, absorbents); Benzophenone (absorbent), benzotriazole (absorbent), nickel derivative (quenching agent), radical scavenger (Radical Scavenger), and the like.

As the heat stabilizer, polyphenol-based, phosphite-based and lactone-based heat stabilizers may be used, and the UV stabilizer and heat stabilizer may be mixed in an appropriate amount at a level that does not affect UV curability.

The additive (F) is preferably used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the total composition.

<Optical Film>

In addition, the present invention provides an optical film having a hard coat layer formed of the composition for forming the hard coat layer.

The optical film of the present invention includes a base film having a hard coat layer formed of the composition on at least one surface.

The base film may be used without particular limitation as long as it is a transparent polymer film, for example, triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester , polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, poly The film may be formed of a polymer such as ether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polycarbonate. These polymers can be used individually or in mixture of 2 or more types.

Among the base films, in the case of a crystalline polymer base film, an engineering plastic base film, and a polymer base film whose surface has changed to hydrophilic due to hydrolysis or saponification, it is difficult to increase adhesion when using a conventional composition for forming a hard coating layer. In some cases, mechanical properties may be deteriorated. However, the composition for forming a hard coat layer of the present invention described above can implement excellent adhesion to these base films without deterioration of mechanical properties.

The base film may have been subjected to surface treatment such as plasma treatment or corona treatment to improve adhesion with the hard coating layer.

The hard coating layer is formed by applying and curing a composition for forming a hard coating layer on a base film, and the application is a slit coating method, a knife coating method, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method , roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, gravure printing method, flexographic printing method, offset printing method, inkjet coating method, dispenser printing method, nozzle coating method, capillary coating method A known method such as these can be used.

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

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

<Image display device>

In addition, the present invention provides an image display device having the hard coating film.

Since the hard coating film of the present invention has excellent hardness and flexibility, the hard coating film may be used, for example, as an outermost window film of an image display device, and in particular, it may be preferably applied to a flexible image display device.

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

Hereinafter, preferred embodiments are presented to help the understanding of the present invention, but these examples are merely illustrative of the present invention and do not limit the appended claims, and are within the scope and spirit of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible, and it is natural that such variations and modifications fall within the scope of the appended claims.

production example - polymeric ingredient

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

division Silsesquioxane compound photopolymerizable compound ingredient content urethane oxyethylene Other content Preparation Example 1 A-1/A-2 10/20 B-2/B-3 B'-1 - 30/10/30 Preparation 2 A-1/A-2 20/10 B-2 B'-1 B"-1 20/30/20 Preparation 3 A-1/A-2 10/10 B-1/B-3 B'-1/B'-2 B"-1 40/10/10/10/10 Preparation 4 A-1/A-2 15/5 B-2/B-3 B'-2 - 20/20/40 Preparation 5 A-1/A-2 5/15 B-1 B'-1/B'-2 - 50/20/10 Preparation 6 A-1/A-2 10/10 B-2/B-3 B'-2 - 50/20/10 Preparation 7 A-1/A-2 15/5 B-1/B-3 B'-1/B'-2 B"-1 10/30/10/20/10 Preparation 8 A-1/A-2 5/15 B-2/B-3 B'-1/B'-2 - 40/10/10/20 Preparation 9 A-1 20 B-2/B-3 B'-2 - 20/20/40 Preparation 10 A-2 20 B-2/B-3 B'-1/B'-2 - 40/10/10/20 Preparation 11 A-1/A-2 20/18 B-2/B-3 B'-1 - 25/12/25 Preparation 12 - - B-3 B'-1/B'-2 B"-1 30/30/10/30 Preparation 13 - - B-3 B'-1 B"-1 20/30/50 Preparation 14 - - B-2/B-3 B'-2 - 40/20/40 Preparation 15 - - B-3 B'-1/B'-2 - 30/30/40 Preparation 16 A-4 20 B-2/B-3 B'-2 - 20/20/40

, 다면체 실세스퀴옥산의 각 Si에 상기 반복 단위가 결합되어 있음
A-2:

, 다면체 실세스퀴옥산의 각 Si에 상기 반복 단위가 결합되어 있음
A-3: 메타아크릴 POSS (MA0735, 하이브리드 플라스틱스)
B-1: 신아 T&C SOU-1700B

B-2: 신아 T&C SOU-1290

B-3: UA-306H (공영사)

B’-1: M4004 (미원스페샬리티 케미칼)

B'-2: DPEA126(일본화약)

B"-1: M-340(미원스페샬리티 케미칼)

A-1:

, the repeating unit is bonded to each Si of the polyhedral silsesquioxane
A-2:

, the repeating unit is bonded to each Si of the polyhedral silsesquioxane
A-3: methacrylic POSS (MA0735, hybrid plastics)
B-1: Shin-A T&C SOU-1700B

B-2: Shina T&C SOU-1290

B-3: UA-306H (public corporation)

B'-1: M4004 (Miwon Specialty Chemical)

B'-2: DPEA126 (Japanese gunpowder)

B"-1: M-340 (Miwon Specialty Chemicals)

Example and comparative example

Based on 30 parts by weight of a mixture of polymerizable components according to the components and contents of Table 1, Nanopol 784 (Evonik, PGEMA 50% diluted 20 nm silica sol) 30 parts by weight, photoinitiator igacure 184 (BASF) 5 parts by weight, leveling By adding 3 parts by weight of No. BYK-333, 30 parts by weight of methyl ethyl ketone, and 10 parts by weight of toluene, Examples 1 to 11 (using Preparations 1 to 11), Comparative Examples 1 to 5 (using Preparation Examples 12 to 16) A composition for forming a hard coating was prepared.

Experimental example

The compositions for forming hard coatings of Examples and Comparative Examples were coated on an 80 μm optical polyimide film (Mitsubishi Gas Chemical, 100 μm, L-3430) using a bar coater and dried to a thickness of 20 μm. After drying in an oven at ℃ for 2 minutes, using a high-pressure mercury lamp irradiated at 350mJ/cm ² to prepare a hard coating film.

1. Pencil hardness

Using a pencil hardness tester (PHT, Seokbo Science Co., Korea), a load of 500 g was applied and the pencil hardness was measured. For the pencil, a Mitsubishi product was used, and the experiment was performed 5 times per pencil hardness.

2. scratch resistance

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

Steel wool #0000 was used.

<Evaluation criteria>

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 to 30 scratches

D: 31 or more scratches

3. Adhesion

After making 100 squares by drawing 11 straight lines horizontally and vertically at 1 mm intervals on the coated side of the film, a peel test was performed three times using a tape (CT-24, Nichiban, Japan). Three 100 squares were tested and the average was recorded.

The adhesion was recorded as follows.

Adhesion = n/100

n: the number of non-exfoliated rectangles among all rectangles

100: the total number of squares

Therefore, when no peeling occurred, it was recorded as 100/100.

4. curl

A sample cut into a square shape of A4 size (29.7 × 21.0 cm) is placed on a flat glass plate, with the film coated side facing up, and the distance from the square glass plate is measured at 25°C and 50%RH, and the average value is obtained It was set as the measured value.

5. mandorel

In order to evaluate the flexibility and cracking properties of the coating film, the coated film sample cut to a size of 1cmx10cm is placed on an iron rod of each diameter (2φ~10φ), and the coating layer is turned up by hand so that the surface is not cracked. 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 6H 6H 6H 6H 6H 7H scratch resistance S S S S S S S A A A A adhesion 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/00 90/100 curl 4mm 4mm 4mm 4mm 4mm 4mm 4mm 5mm 7mm 7mm 10 mm mandorel 3φ 3φ 3φ 3φ 3φ 3φ 3φ 3φ 5φ 5φ 8φ

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 pencil hardness F F F HB B scratch resistance C C C C C adhesion 70/100 65/100 72/100 65/100 65/100 curl 15mm 12mm 15mm 20mm 13mm mandorel 10φ 10φ 10φ 10φ 10φ

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

However, it was confirmed that the comparative examples did not secure hardness and flexibility at the same time, and thus were not suitable for a window substrate of a flexible display.

Claims (10)

a dendrimer polyhedral oligomer silsesquioxane compound (A) having a (meth)acrylate group at the branch terminal; And a urethane-based (meth) acrylate resin and a polymerizable compound (B) comprising (meth) acrylate having an oxyethylene group; A composition for forming a hard coating comprising a.
The composition for forming a hard coating according to claim 1, wherein the silsesquioxane compound is a dendrimer polyhedral oligomeric silsesquioxane compound having 6 to 12 structural units represented by Formula 1 below:
[Formula 1]
_{RSiO 1.5}
(Wherein, R is each 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 in each structural unit is a structure of the following formula (2))
[Formula 2]

(Wherein, R ₁ is an alkylene group having 1 to 6 carbon atoms, R ₂ , R ₃ and R ₄ are each independently a direct bond or an alkylene group having 1 to 6 carbon atoms, and R ₅ , R ₆ and R ₇ are each other independently a hydrogen atom or a methyl group, and n is an integer from 1 to 3).
The composition for forming a hard coating according to claim 2, wherein in Formula 2, n is 1 or 2.
The composition for forming a hard coating according to claim 1, comprising 5 to 35 parts by weight of the silsesquioxane compound with respect to 100 parts by weight of the total weight of the polymerizable component (mixed weight of (A) and (B)).
The method according to claim 1, 20 to 70 parts by weight of a urethane-based acrylate, 10 to 50 parts by weight of a (meth)acrylate containing an oxyethylene group with respect to 100 parts by weight of the polymerizable component (total weight of (A) and (B)) A composition for forming a hard coating comprising.
The composition for forming a hard coating according to claim 1, further comprising at least one photopolymerization initiator (C) selected from the group consisting of acetophenone-based photoinitiators and aminoketone-based photoinitiators.
The composition for forming a hard coating according to claim 1, further comprising inorganic nanoparticles.
An optical film comprising a coating layer formed of the composition for forming a hard coating according to any one of claims 1 to 7 on at least one surface of the base film.
The optical film of claim 8 , wherein the optical film is a window film.
The image display apparatus provided with the optical film of Claim 8.