TWI696671B - Compositon for hard coating, optical film and display device using the same - Google Patents

Abstract

The present invention provides a composition for forming a hard coat layer. The present invention relates to a composition for forming a hard coat layer, an optical film, and an image display device thereof. The composition for forming a hard coat layer includes a dendrimer compound (A), a photopolymerizable compound (B), and a specific structure. The photopolymerization initiator (C) and the solvent (D) can achieve an appropriate curing density, thereby ensuring the hardness of the hard coat layer while greatly improving curling characteristics and flexibility.

Description

Composition for forming hard coat layer, optical film and image display device

The invention relates to a composition for forming a hard coat layer, an optical film and an image display device thereof.

In recent years, thin display devices using flat panel display devices such as liquid crystal display devices or organic light emitting diode display devices have attracted attention. In particular, these thin display devices are implemented in the form of touch screen panels, not only smart phones and tablet PCs, but also up to various wearable devices. It is widely used in various smart devices characterized by portability.

In order to protect the display panel from scratches and external impacts, the display device based on these portable touch screen panels is equipped with a window film for display protection on the display panel, and the display is reinforced in almost all cases The glass acts as a window membrane. Tempered glass for displays is thinner than ordinary glass, but has the characteristics of high strength and scratch resistance.

However, the high weight of tempered glass is not only unsuitable for lightweighting of portable devices, but also fragile to external shocks. Therefore, it is difficult to achieve unbreakable properties and it cannot be bent above a certain level. Therefore, tempered glass is not suitable as a raw material for flexible displays having bendable or foldable functions.

Recently, active research has been conducted on optical plastic covers that have strength and scratch resistance equivalent to strengthened glass while ensuring flexibility and impact resistance. Generally, as a raw material of a cover made of optical transparent plastic that is softer than strengthened glass, there are polyethylene terephthalate (PET), polyether sock (PES), polyethylene naphthalate Alcohol ester (PEN), polyacrylate (PAR), polycarbonate (PC), polyimide (PI), etc. However, these polymer plastic substrates not only show insufficient physical properties in terms of hardness and scratch resistance, but also have insufficient impact resistance compared with the strengthened glass used as a window film for display protection. Therefore, various attempts have been made to supplement the required physical properties by applying a composite resin composition to these plastic substrates.

Thus, a hard coat layer is provided on the plastic base film to ensure high hardness. For a general hard coat layer, a composition consisting of a resin containing a photocurable functional group and a curing agent, or a curing catalyst, and other additives is used. In particular, in the case of a composite resin with a high functional group, it is applied to The plastic substrate film for optics can be used as a window for protecting displays with improved hardness and scratch resistance.

However, general photo-curable composite resins not only have difficulty in achieving high hardness equivalent to strengthened glass, but also greatly cause curling caused by shrinkage during curing, and also have insufficient flexibility, so they have unsuitable applications. The shortcomings of the window film used in the protection of flexible displays.

Korean Patent Publication No. 2013-74167 (Patent Document 1) discloses a plastic substrate.

Existing technical literature

Patent Literature

Patent Document 1: Korean Patent Publication No. 2013-74167

An object of the present invention is to provide a composition for forming a hard coat layer capable of producing a hard coating film capable of achieving both high hardness and flexibility and suppressing curl.

Moreover, the objective of this invention is to provide the optical film provided with the hard-coat layer formed from the said composition for hard-coat layer formation.

Furthermore, an object of the present invention is to provide an image display device provided with the optical film.

1. A composition for forming a hard coat layer, which contains a dendrimer compound (A) represented by the following Chemical 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

，m為2或3，R₃為氫原子或(甲基)丙烯酸酯基，分子 內的至少一個R₃為(甲基)丙烯酸酯基。) (In the formula, n is an integer of 2 to 4, R ₁ is an alkyl group having 2 to 5 carbon atoms, and R ₂ is

, 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. )

，至少一個R₃為

，x 為2或3，R₄為氫原子或(甲基)丙烯酸酯基，分子內的至少一個R₄為(甲基)丙烯酸酯基。 2. The composition for forming a hard coat layer according to the above item 1, wherein in the above chemical formula 1, R ₃ is a hydrogen atom or

, At least one R ₃ is

, 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 composition for forming a hard coat layer according to the above item 1, which contains 10 to 50 parts by weight of the above-mentioned chemical formula 1 with respect to a total of 100 parts by weight of the polymerizable component (mixed weight of (A) and (B)) Represented dendrimer compound (A).

4. The composition for forming a hard coat layer according to the above item 1, wherein the photopolymerizable compound (B) contains a (meth)acrylic acid selected from a urethane-based (meth)acrylate and an oxyethylene group. At least one of the esters.

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

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

7. The composition for forming a hard coat layer according to the above item 1, which further contains inorganic nano particles.

8. An optical film provided with a coating layer formed from the composition for forming a hard coating layer according to any one of items 1 to 7 on at least one surface of a base film.

9. The optical film of the above item 8, wherein the optical film is a window film.

10. An image display device comprising the optical film according to item 8 above.

The composition for forming a hard coat layer of the present invention can achieve an appropriate curing density by containing a dendrimer compound having a specific structure. Thereby, curling characteristics and flexibility can be greatly improved while ensuring the hardness of the hard coat layer.

In addition, since the composition for forming a hard coat layer of the present invention has excellent curling properties and flexibility, it can be suitably applied to flexible displays.

The present invention relates to a composition for forming a hard coat layer, and more specifically, to a dendrimer compound (A), a photopolymerizable compound (B), a photopolymerization initiator (C), and a solvent containing a specific structure ( D) It is possible to achieve an appropriate curing density, thereby ensuring the hardness of the hard coating layer while greatly improving curling characteristics and flexibility of the composition for forming a hard coating layer and using the composition for forming a hard coating layer Optical film and image display device.

The present invention will be described in detail below.

<Composition for hard coat layer formation>

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

Dendrimer (A)

The composition for forming a hard coat layer according to the present invention contains a dendrimer compound (A) represented by the following Chemical Formula 1.

[Chemical Formula 1](R ₁ ) _4-n C(CH ₂ OR ₂ ) _n

，m為2或3，R₃為氫原子或(甲基)丙烯酸酯基， 分子內的至少一個R₃為(甲基)丙烯酸酯基。 (In the formula, n is an integer of 2 to 4, R ₁ is an alkyl group having 2 to 5 carbon atoms, and R ₂ is

, 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 Chemical Formula 1 becomes the second-generation dendrimer compound, and by including at least one (meth)acrylate group at the end of the branch, it can be used in the composition for forming a hard coat layer The role of polymerizable compounds.

，至少一個R₃為

，x為2或3，R₄為氫原子或(甲基)丙烯酸酯基，分子 內的至少一個R₄可以為(甲基)丙烯酸酯基。 According to another embodiment of the present invention, for the dendrimer compound, R ₃ in the above Chemical Formula 1 is a hydrogen atom or

, At least one R ₃ is

, 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 Chemical Formula 1 becomes the third-generation dendrimer compound, and by including at least one (meth)acrylate group at the end of the branch, it can be used in the composition for forming a hard coat layer The role of polymerizable compounds.

Dendrimer compounds are compounds whose molecular chains polymerize regularly from the center to the outside in accordance with certain rules. The "generation" in the dendrimer compound means the number of branches formed by polymerization reaction of the polymerizable functional group based on the center. When the formed branch end of the first generation undergoes a polymerization reaction again, it becomes the second generation, and the repeated polymerization reaction proceeds.

In the above formula, n, m, and x mean the number of generations per generation, which means the number of polymerizable functional groups that can undergo a polymerization reaction in each generation. The total number of occurrences of synthesized dendrimer compounds means multiplying the number of occurrences of each generation.

In the present invention, the dendritic macromolecular compound represented by the above Chemical Formula 1 is a polymerizable component ((A) and (B)) of the composition for forming a hard coat layer and adjusts the molecular weight and crosslink density of the polymer during the polymerization reaction To the appropriate range of ingredients. Specifically, the dendrimer compound of the above Chemical Formula 1 is polymerized on the basis of the center portion during polymerization to have an outer side In the direction of the branch, a polymerizable functional group is formed at the end of each branch. Thus, as compared with the polymerization reaction of the polymerizable compound having a normal structure, since it has more functional groups than the molecular weight of the polymer, it is possible to achieve excellent hardness characteristics.

In addition, since the dendrimer compound of Chemical Formula 1 contains only a polymerizable functional group at the end, the center of the polymer can ensure appropriate flexibility. Thereby, curling characteristics and flexibility can be improved while ensuring the hardness of the hard coat layer.

The schematic polymerization reaction formula of the dendrimer compound according to an embodiment of the present invention is shown below.

From the above reaction formula, it can be seen that the dendrimer compound according to an embodiment of the present invention forms a first-generation dendrimer structure in which DMPA is condensed with TMP as the central portion. Then, as a branched structure, DMPA is repeatedly condensed and polymerized to continuously increase the generation number of dendrimers. After the third generation, condensation polymerization of acrylic acid and the like at the terminal group can form a dendrimer having a multifunctional acryloyl group at the terminal Compound.

In the present invention, in terms of achieving the above-mentioned effects, preferably, the dendrimer compound represented by Chemical Formula 1 has a second-generation or third-generation structure. If the reaction proceeds beyond the third generation, the problem of gelation occurs.

In the present invention, the content of the dendrimer compound represented by Chemical Formula 1 is not particularly limited. For example, it may be 10 with respect to a total of 100 parts by weight of the polymerizable component (mixed weight of (A) and (B)). ~50 parts by weight, preferably 20~40 parts by weight. If the above range is satisfied, curling characteristics and flexibility can be achieved while ensuring excellent hardness. If it is less than 10 parts by weight, the flexibility may decrease. If it exceeds 50 parts by weight, the presence of unreacted functional groups due to the steric hindrance effect makes it difficult to ensure hardness characteristics.

Photopolymerizable compound (B)

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

The type of the photopolymerizable compound (B) is not particularly limited. For example, it may be a monofunctional compound or a polyfunctional compound having a polymerizable unsaturated group. These can be used individually or in mixture of 2 or more types.

A compound having 1 to 3 polymerizable unsaturated groups in the molecule does not reduce the crosslink density during curing, and can improve the curling characteristics of the cured product. In addition, the polyfunctional compound having four or more polymerizable unsaturated groups in the molecule is a component that increases the crosslink density during curing and imparts excellent hardness to the hard coat layer.

As specific examples of the photopolymerizable compound of the present invention, examples of the monomer containing at least one (meth)acrylate functional group as a polymerizable functional group include dipentaerythritol hexa(meth)acrylate and dipentaerythritol penta(methyl) ) Acrylate, pentaerythritol tetra (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, oxyethylene containing (meth) acrylate, ester (meth) acrylate, Ether (meth)acrylate, urethane (meth)acrylate, 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. Specific examples include (meth)acrylates, N-vinyl compounds, vinyl-substituted aromatic compounds, vinyl ethers, and vinyl esters.

Examples of (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin tri(meth)acrylate, and tri(2-hydroxyethyl)isocyanate. Cyanurate 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-hexanediol 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 with ethylene oxide or propylene oxide added to the above (meth)acrylate; it has 1 to 3 Oligoester (meth)acrylate, oligoether (meth)acrylate, oligourethane (meth)acrylate, oligomeric epoxy (meth)acrylate; Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, the product of adding ethylene oxide or propylene oxide to the (meth)acrylate; single (Meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, stearate (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (meth)acrylic acid Phenoxyethyl ester. In addition, examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylphthalimide, and N-vinylsuccinimide. Examples of the vinyl-substituted aromatic compound include styrene, divinylbenzene, chloromethylstyrene, hydroxystyrene, α-methylstyrene, bromomethylstyrene, and tribromomethylstyrene. Examples of vinyl ethers include diethylene glycol monomethyl vinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, and triethylene glycol divinyl ether. Examples of vinyl esters include vinyl acetate, vinyl propionate, and vinyl benzoate.

Among the above-mentioned photopolymerizable compounds, urethane-based (meth)acrylates can be used from the viewpoint of improvement in hardness. In addition, from the viewpoint of improving flexibility, (meth)acrylate containing oxyethylene can be used. Preferably, a urethane-based (meth)acrylate and an oxyethylene-containing (meth)acrylate can be used together.

In the present invention, the urethane-based acrylate can be produced by performing a condensation reaction between a diisocyanate compound and a polyfunctional (meth)acrylate compound having a hydroxyl group.

The type of the diisocyanate compound is not particularly limited, and preferably, it may be a compound substituted with a cyclohexyl group. Thus, the urethane acrylate can have a substituent of cyclohexyl group. In this case, due to the structural stability of the cyclohexyl group, it has both hardness and flexibility, which is preferred in this regard.

Specific examples of the diisocyanate compound substituted with cyclohexyl include 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and the like. However, it is not limited to these, specifically, the compounds represented by the following Chemical Formulas 2 and 3 and the like.

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

In the present invention, the oxyethylene group-containing acrylate can obtain a polyfunctional alcohol having an oxyethylene group by performing an addition reaction between ethylene oxide and a polyhydric alcohol. The functional alcohol is produced by condensation reaction. Specific examples of the polyhydric alcohol include glycerin, trimethylolpropane, pentaerythritol, and dipentaerythritol, but are not limited to these.

Specific examples of the oxyethylene (EO)-containing acrylic ester include trimethylolpropane (EO) ₃ tri(meth)acrylate and trimethylolpropane (EO) ₆ tri(methyl ) 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, di Pentaerythritol (EO) ₆ hexa(meth)acrylate, dipentaerythritol (EO) ₁₂ hexa(meth)acrylate, dipentaerythritol (EO) ₁₈ hexa(meth)acrylate, etc. However, it is not limited to these, specifically, the compounds represented by the following Chemical Formulas 4 and 5 and the like.

In the present invention, the content of the photopolymerizable compound (B) is not particularly limited. For example, it may be 65 to 95 parts by weight with respect to the total of 100 parts by weight of the polymerizable components (mixed weight of (A) and (B)). The part may preferably be 60 to 80 parts by weight. If the above range is satisfied, excellent mechanical properties can be ensured.

In the present invention, when the urethane-based (meth)acrylate and the oxyethylene-containing acrylate are mixed and used as the photopolymerizable compound (B), the content of the p-urethane-based acrylate It is not particularly limited, and for example, it may be 20 to 70 parts by weight, preferably 40 to 50 parts by weight with respect to a total of 100 parts by weight of the polymerizable components (the mixed weight of (A) and (B)). If the above range is satisfied, excellent mechanical properties can be ensured. If it is less than 20 parts by weight, the hardness may decrease, and if it exceeds 70 parts by weight, the coating may curl, break, or crack due to an excessive increase in shrinkage force.

In addition, the content of the oxyethylene group-containing (meth)acrylate is not particularly limited. For example, it may be 10 with respect to a total of 100 parts by weight of the polymerizable component (mixed weight of (A) and (B)). ~50 parts by weight, preferably 30-40 parts by weight. If the above range is satisfied, flexibility can be achieved while ensuring excellent mechanical properties. If it is less than 10 parts by weight, the mechanical properties may decrease due to a decrease in curing density, and if it exceeds 50 parts by weight, it may be difficult to ensure flexibility due to an increase in curing density.

Photopolymerization initiator (C)

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

Among the photopolymerization initiators (C) are Type I type initiators that generate radicals due to the decomposition of molecules caused by the difference in chemical structure or molecular bond energy, and Type II type initiators that coexist with tertiary amines and draw hydrogen.

Specific examples of Type I initiators include 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 4-tert-butyltrichloroacetophenone, diethoxy Acetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 1 -(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)one , 1-hydroxycyclohexyl phenyl ketone and other acetophenones, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin dimethyl ketal and other benzoin, acetyl oxidation Phosphines, titanocene compounds, etc.

Specific examples of the Type Ⅱ type initiator include benzophenone, benzoyl benzoic acid, benzoyl benzoic acid methyl ether, 4-phenyl benzophenone, hydroxybenzophenone, 4 -Benzophenone-4'-methyldiphenyl sulfide, 3,3'-methyl-4-methoxybenzophenone and other benzophenones, thioxanthone, 2-chlorothioxanthone Ketone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, etc.

One type of photopolymerization initiator may be used, or two or more types may be used in combination. In addition, Type I and Type Ⅱ can be used alone or in combination.

As a commercially available product of a photopolymerization initiator, there is Irgacure 184 (manufactured by BASF) and the like.

In the present invention, the content of the photopolymerization initiator (C) is not particularly limited. For example, it may be 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to the total 100 parts by weight of the composition. . If the above range is satisfied, excellent mechanical properties and adhesion can be achieved. If it is less than 0.1 parts by weight, curing may not proceed sufficiently, and the mechanical properties and adhesion of the final coating film may decrease. If it exceeds 10 parts by weight, cracking, curling, etc. due to curing shrinkage may occur.

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 aforementioned 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 esters (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxyacetate, etc.), cellosolve series (methyl cellosolve, Ethyl cellosolve, propyl cellosolve, etc.), hydrocarbons (n-hexane, n-heptane, benzene, toluene, xylene, etc.), etc. These can be used individually or in mixture of 2 or more types.

In the present invention, the content of the solvent is not particularly limited. For example, it may be 5 to 90 parts by weight, preferably 20 to 70 parts by weight with respect to a total of 100 parts by weight of the composition. If it is within the range of the above content, appropriate coatability can be achieved, which is preferable. On the other hand, if it is less than 5 parts by weight, the viscosity is high, and the coatability is lowered. If it exceeds 90 parts by weight, it may be difficult to adjust the thickness of the coating film, uneven drying may occur, and appearance defects may occur.

Inorganic nanoparticles (E)

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

The inorganic nano particles (E) are uniformly formed in the coating film, and can 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, and may be, for example, 1 to 100 nm, preferably 5 to 50 nm. Within the above range, excellent mechanical properties can be achieved. On the other hand, if the average particle diameter is less than 1 nm, agglomeration of particles occurs, and a uniform coating film cannot be formed. If it exceeds 100 nm, not only the optical characteristics but also the mechanical characteristics are reduced.

The type of the inorganic nanoparticles (D) is not particularly limited. For example, it may be a metal oxide and can be selected from Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , and Ta ₂ O ₅ , Ti ₃ O ₅ , ITO, IZO, ATO, ZnO-Al, Nb ₂ O ₃ , SnO, MgO, and one of their combinations, preferably, Al ₂ O ₃ , SiO ₂ , ZrO ₂ can be used Wait.

In the present invention, the content of the inorganic nanoparticles (D) is not particularly limited. For example, it may be 10 to 50 parts by weight based on 100 parts by weight of the total composition. Within the range of the above content, the mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness are excellent. On the other hand, if it exceeds 50 parts by weight, curability may be hindered, but mechanical properties may be reduced, and appearance defects may occur.

The inorganic nanoparticles can be used after being diluted to a concentration of 10 to 80% by weight in an organic solvent.

Additive (F)

The composition for forming a hard coat layer according to the present invention may further contain additives in addition to the aforementioned components as necessary, and examples thereof include leveling agents, ultraviolet stabilizers, and heat stabilizers.

The leveling agent is added to improve the smoothness and coatability of the coating film when the composition is applied, and a silicon leveling agent, a fluorine-based leveling agent, an acrylic leveling agent, or the like can be used. As a commercial product of the above-mentioned leveling agent, BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, TEGO company of BYK CHEMIE can be used TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, FC-4430, FC-4432 of 3M Company, etc.

The ultraviolet stabilizer is added in order to prevent the surface of the coating film from being discolored or easily damaged due to continuous ultraviolet irradiation, and plays a role of shielding or absorbing ultraviolet rays. The above-mentioned ultraviolet stabilizers can be divided into absorbers, extinction agents (Quenchers), and hindered amine light stabilizers (HALS, Hindered Amine Light Stabilizer) according to the mechanism of action, for example, phenyl salicylate (absorbent), disulfide Benzophenone (absorber), Benzotriazole (absorber), nickel derivative (matting agent), radical scavenger (Radical Scavenger), etc.

As the heat stabilizer, polyphenol-based, phosphite-based, and lactone-based heat stabilizers can be used. The above-mentioned ultraviolet stabilizer and heat stabilizer can be mixed and used in an appropriate content at a level that does not affect ultraviolet curability.

The above 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.

<optical film>

In addition, the present invention provides an optical film provided with a hard coat layer formed from the composition for forming a hard coat layer.

The optical film of the present invention includes a base film provided with a hard coat layer formed from the above composition on at least one side.

The base film can be used without any particular limitation as long as it is a transparent polymer film, and examples thereof include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, and acrylic Cellulose, butyl cellulose, acetyl propyl cellulose, polyester, polystyrene, poly amide, polyether amide imide, polyacrylic acid, poly amide imide, polyether sock, poly sock, polyethylene , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, poly Films made of polymers such as ethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycarbonate. These polymers can be used alone or in combination of two or more.

In the base film, in the case of a crystalline polymer base film that is difficult to impart adhesion after coating, an engineering plastic base, or a polymer base film that changes its surface to be hydrophilic by hydrolysis or saponification, if it is generally used In the composition for forming a hard coat layer, it may be difficult to improve the adhesion, or the mechanical properties may be reduced. However, the above-mentioned composition for forming a hard coat layer of the present invention does not reduce mechanical properties even with these base films, and can achieve excellent adhesion.

The base film may be a base film that has undergone surface treatments such as plasma treatment and corona treatment in order to improve the adhesion with the hard coat layer.

The hard coat layer is formed by applying a composition for forming a hard coat layer on a base film and curing. For coating, slit coating method, blade coating method, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire wound bar coating can be used Buffalo, 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, etc.

The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm. If the thickness is within the above range, it exhibits excellent hardness and flexibility and can prevent curling.

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

<Image display device>

In addition, the present invention provides an image display device provided with the above hard coat film.

The hard coat film of the present invention is excellent in hardness and flexibility. The above-mentioned hard coat film can be used as, for example, the outermost window film of the image display device, and in particular, it can be suitably applied to a flexible image display device.

The image display device may be a general liquid crystal display device, an electroluminescence display device, a plasma display device, a field emission display device, and various other image display devices.

In the following, preferred embodiments are shown to help the understanding of the present invention, but these embodiments are merely illustrative of the present invention, and do not limit the scope of the attached patent application, and fall within the scope of the present invention and the technical idea The changes to the embodiments are various and can be modified, which is obvious to those with ordinary knowledge in the technical field. Such changes and corrections certainly belong to the scope of the attached patent application.

Manufacturing example-polymerizable component

A-1: The third generation dendrimer compound

A-2: The second generation dendrimer compound

B-1: SOU-1700B (manufactured by SHIN-A T&C)

B-2: SOU-1290 (manufactured by SHIN-A T&C)

B-3: UA-306H (Made by Kyoeisha Chemical Co., Ltd.)

B’-1: M4004 (made by Meiyuan Special Chemicals)

B’-2: DPEA126 (manufactured by Nippon Kayaku)

B”-1: M300 trimethylolpropane triacrylate (made by Meiyuan Special Chemicals)

B'”-2: M600 dipentaerythritol hexaacrylate (made by Meiyuan Special Chemicals)

B'”-3: M-340 (made by Meiyuan Special Chemicals)

Examples and comparative examples

For mixtures of polymerizable components [Examples 1 to 14 (using compositions of Production Examples 1 to 14) and Comparative Examples 1 to 4 (using compositions of Production Examples 15 to 18) based on the ingredients and contents in Table 1] 30 parts by weight, 30 parts by weight of Nanopol 784 (manufactured by EVONIK, 50% PGEMA diluted 20 nm silica sol), 5 parts by weight of photoinitiator igacure184 (manufactured by BASF), 3 parts by weight of leveling agent BYK-333 Parts, 30 parts by weight of methyl ethyl ketone, and 10 parts by weight of toluene, to produce a composition for forming a hard coat layer.

experiment method

The hard coating layer forming compositions of Examples and Comparative Examples were applied to an 80 μm polyimide film for optics (manufactured by Mitsubishi Gas Chemical Co., 100 μm, L-3430) using a bar coater and applied to dry The thickness after that became 20 μm, and it was dried in an oven at 80° C. for 2 minutes. Then, a high-pressure mercury lamp was irradiated at 350 mJ/cm ² to produce a hard coat film.

(1) Pencil hardness

Using a pencil hardness tester (PHT, manufactured by SUKBO Scientific Co., Ltd., Korea), a load of 500 g was applied to measure the pencil hardness. Mitsubishi products were used for the pencils, and each pencil hardness was subjected to an average of 5 experiments, and the maximum pencil hardness shown below was defined as the pencil hardness of the hard coating layer.

(2) Scratch resistance

Using a steel wool testing machine (WT-LCM100, manufactured by Korea PROTECH Co., Ltd.), the reciprocating motion was performed 10 times at 1 kg/(2 cm×2 cm) to test the scratch resistance. As steel wool, the number 0000 is used.

<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

Eleven cuts were formed on the coated surface of the film at 1 mm intervals in the vertical and horizontal directions, and 100 regular quadrilaterals were formed. Then, three times of peeling tests were carried out using an adhesive tape (CT-24, manufactured by Nichiban Japan), and the average value of the number of peeled quadrilaterals was recorded.

Adhesion is recorded as described below.

Adhesion = n/100

(n: the number of quads that have not been stripped out of all quads, 100: the number of quads all)

It should be noted that in the case where none was peeled off, it was recorded as 100/100.

(4) curl

Place the sample cut into A4 size (29.7×21.0cm ² ) on a flat glass plate so that the coated surface of the film is on top, and measure the distance between the 4 corners and the glass plate at 25°C and 50%RH The average value is used as the measured value.

(5) Mandrel

In order to evaluate the flexibility and cracking of the coating film, the coated film samples cut into a size of 1 cm×10 cm were placed on iron rods of various diameters (2 φ~10 φ) with the coating on top. Bending by hand, showing the smallest diameter where no cracks were generated on the surface.

As is clear from Table 2 above, it can be confirmed that the optical films formed from the composition for forming a hard coat layer according to the present invention are excellent in both pencil hardness and flexibility.

On the other hand, in the comparative example in which the dendrimer compound according to the present invention is not used, it can be confirmed that both hardness and flexibility cannot be ensured, and it is not suitable for a window substrate of a flexible display or the like.

Claims (7)

A composition for forming a hard coat layer, comprising a dendrimer compound (A) represented by the following Chemical Formula 1, a photopolymerizable compound (B), a photopolymerization initiator (C), and a solvent (D); wherein The photopolymerizable compound (B) contains a urethane-based (meth)acrylate and an oxyethylene-containing (meth)acrylate, wherein the polymerizable components ((A) and (B) 100 parts by weight of the mixed weight), the dendrimer compound (A) contains 10 to 50 parts by weight, the urethane-based (meth)acrylate contains 20 to 70 parts by weight, and the oxyethylene group The (meth)acrylate contains 10 to 50 parts by weight, [Chemical Formula 1] (R ₁ )C(CH ₂ OR ₂ ) ₃ ; In the formula, R ₁ is an alkyl group with 2 to 5 carbon atoms; R ₂ is

; M is 2 or 3; R ₃ is (meth)acrylate group or

, X is 2 or 3, and R ₄ is a (meth)acrylate group. The composition for forming a hard coat layer according to claim 1, wherein the urethane-based (meth)acrylate is a product substituted with a cyclohexyl group. The composition for forming a hard coat layer according to claim 1, wherein the photopolymerization initiator (C) is at least one selected from the group consisting of an acetophenone-based photoinitiator and an aminoketone-based photoinitiator. The composition for forming a hard coat layer according to claim 1, further comprising inorganic nano particles. An optical film, at least one side of a base film of which includes a coating layer formed by the composition for forming a hard coating layer according to any one of claims 1 to 4. The optical film according to claim 5, wherein the optical film is a window film. An image display device including the optical film according to claim 5.