KR20170075342A - Hard Coating Composition and Hard Coating Film Using the Same - Google Patents

Abstract

The present invention relates to a hardcoat composition comprising an alkoxysilane compound having an epoxy group or a polysiloxane resin prepared by a sol-gel reaction of the alkoxysilane compound, an inorganic nanoparticle, a photopolymerization initiator and a solvent, a hard coating film formed using the same, And an image display device provided with the hard coating film. The hard coating film according to the present invention has excellent hardness, flexibility, excellent scratch resistance, and excellent adhesion and curling properties.

Description

[0001] The present invention relates to a hard coating composition and a hard coating film using the same,

The present invention relates to a hard coating composition and a hard coating film using the hard coating composition. More particularly, the present invention relates to a hard coating composition having excellent hardness and flexibility and a hard coating film formed using the hard coating composition, .

The hard coating film is used for surface protection for image display devices such as a liquid crystal display device, an electroluminescence (EL) display device, a plasma display (PD), and a field emission display (FED).

In recent years, a flexible display device capable of maintaining the display performance even if bent like paper by using a flexible material such as plastic instead of a conventional glass substrate has rapidly emerged as a next-generation display device, and hardness High hardness, scratch resistance, and curl of the edge of the film do not occur during the production process or use, and a hard coating film which does not generate cracks with appropriate flexibility is being studied.

Korean Patent Laid-Open Publication No. 2013-0135151 discloses a hard coating composition containing a monomer for a binder, inorganic fine particles, a photoinitiator and an organic solvent containing 3 to 6 functional acrylate monomers and exhibiting high hardness and no curling or cracking I am suggesting.

However, in the case of such conventional hard hard coating compositions, there is a problem that the flexibility is not sufficient.

Korea Patent Publication No. 2013-0135151

It is an object of the present invention to provide a hard coating composition which can be used in the production of a hard coating film having excellent hardness and excellent flexibility.

It is another object of the present invention to provide a hardcoat film formed using the hardcoat composition.

It is still another object of the present invention to provide an image display device provided with the hard coating film.

On the other hand, the present invention provides a hardcoat composition comprising an alkoxysilane compound having an epoxy group of the following formula (I) or a polysiloxane resin prepared by the sol-gel reaction of the alkoxysilane compound, an inorganic nanoparticle, a photopolymerization initiator and a solvent :

(I)

R ¹ _n Si (OR ² ) _4-n

Wherein R ¹ is an epoxy group, R ² is an alkyl group having 1 to 20 carbon atoms, and n is an integer of 1 to 3.

In one embodiment of the present invention, the alkoxysilane compound having the epoxy group of the above formula (I) is at least one compound selected from the group consisting of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. ≪ / RTI >

In one embodiment of the present invention, the polysiloxane resin may be prepared by subjecting an alkoxysilane compound having an epoxy group of the formula (I) to a sol-gel reaction in the presence of a catalyst.

On the other hand, the present invention provides a hard coating film formed using the hard coating composition.

On the other hand, the present invention provides an image display device provided with the hard coating film.

The hard coating film formed using the hard coating composition according to the present invention has excellent hardness and flexibility as well as excellent scratch resistance, adhesiveness and curling property, and can be effectively used for a window of a flexible display device.

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

An embodiment of the present invention relates to a hardcoat composition comprising an alkoxysilane compound having an epoxy group of the following general formula (I) or a polysiloxane resin prepared by a sol-gel reaction of the alkoxysilane compound, an inorganic nanoparticle, a photopolymerization initiator and a solvent will be:

(I)

R ¹ _n Si (OR ² ) _4-n

Wherein R ¹ is an epoxy group, R ² is an alkyl group having 1 to 20 carbon atoms, particularly an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 3.

The epoxy group-containing alkoxysilane compound undergoes a photocationic polymerization reaction with an epoxy group. Since the photocationic polymerization reaction has a relatively low shrinkage ratio and no oxygen inhibition reaction on the surface, stable curing is possible, and the curing rate is excellent. In addition, the polysiloxane resin produced by the sol-gel reaction of the alkoxysilane compound has a high light-ionic polymerization and an excellent curing rate due to the presence of a siloxane network. Such an alkoxysilane compound having an epoxy group and a polysiloxane resin not only provide an excellent hardness to the hard coating composition, but also provide excellent flexibility at the same time.

As used herein, an alkyl group having 1 to 20 carbon atoms or an alkyl group having 1 to 6 carbon atoms means a linear or branched hydrocarbon having 1 to 20 carbon atoms or 1 to 6 carbon atoms, and includes, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, n-hexyl and the like.

The alkoxysilane compound having an epoxy group of the above formula (I) is preferably at least one compound selected from the group consisting of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, Propyl trimethoxysilane, and 3-glycidoxypropyl triethoxysilane.

The polysiloxane resin may be prepared by a hydrolysis-gel reaction of the alkoxysilane compound.

Specifically, the alkoxy group of the alkoxysilane as a starting material is hydrolyzed together with water to form a hydroxyl group, and a siloxane bond is formed by a condensation reaction with an alkoxy group or a hydroxyl group of another alkoxysilane compound to form a polysiloxane.

Catalysts may be preferably introduced to facilitate the hydro-sol-gel reaction. Usable catalysts include acidic catalysts such as acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, chlorosulfonic acid, para-toluic acid, trichloroacetic acid, polyphosphoric acid, pyrophosphoric acid, iodic acid, tartaric acid, perchloric acid, Base catalysts such as butylamine, di-n-butylamine, tri-n-butylamine, imidazole, ammonium perchlorate, potassium hydroxide and barium hydroxide, ion exchange resins such as Amberite IPA- ). The amount of the catalyst to be used is not particularly limited, and 0.0001 to 10 parts by weight may be added to 100 parts by weight of the alkoxysilane.

The hydrosol-gel reaction can be carried out by stirring at room temperature for 6 to 144 hours, and may be carried out at 60 to 80 ° C for 12 to 36 hours for accelerating the reaction rate and proceeding the complete condensation reaction.

The alkoxysilane compound or the polysiloxane resin may be used in an amount of 50 to 90 parts by weight, preferably 55 to 85 parts by weight, based on 100 parts by weight of the solid content in the hard coating composition. When the amount is less than 50 parts by weight, hardness is difficult to be secured. When the amount is larger than 90 parts by weight, the coating film is broken and it may be difficult to impart bending properties.

In one embodiment of the present invention, the inorganic nanoparticles may have an average particle diameter of 1 to 100 nm, preferably 5 to 50 nm. These inorganic nanoparticles are uniformly formed in the coating film, and can improve mechanical properties such as abrasion resistance, scratch resistance and pencil hardness. If the particle size is less than the above range, agglomeration occurs in the composition and a uniform coating film can not be formed. As a result, the above effect can not be expected. On the other hand, if the particle size exceeds the above range, The mechanical properties may be deteriorated.

The inorganic nanoparticles may be a metal oxide and may be selected from the group consisting of Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , ITO, IZO, ATO, ZnO- Nb ₂ O ₃ , SnO ₂ , MgO, and combinations thereof. In particular, Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like can be used.

The inorganic nanoparticles can be manufactured directly or commercially available. In the case of commercially available products, those dispersed in an organic solvent at a concentration of 10 to 80 parts by weight may be used.

The inorganic nanoparticles may be contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the solid content in the hard coating composition. When the amount is less than 10 parts by weight, mechanical properties such as abrasion resistance, scratch resistance and pencil hardness may not be sufficient. If the amount is more than 50 parts by weight, mechanical properties may be deteriorated and appearance may be deteriorated.

In one embodiment of the present invention, the photopolymerization initiator is used for photocuring the hard coating composition, and any initiator that can be used in the art can be used without limitation.

As the photopolymerization initiator, a cationic species or a Lewis acid may be generated by irradiation of an active energy ray such as visible light, ultraviolet light, X-ray or electron beam to use a cationic ion polymerization initiator capable of initiating polymerization reaction of the photocationic curing component .

Since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with a photocationic curable component. Examples of the compound capable of generating a cationic species or a Lewis acid by irradiation with an active energy ray include an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt or an aromatic sulfonium salt; Iron-allene complex and the like. Among them, the aromatic sulfonium salt is preferable because it has ultraviolet ray absorption property even in the wavelength range near 300 nm, and is excellent in curability and can give excellent coating film characteristics. These photocationic polymerization initiators may be used alone or in combination of two or more.

The photopolymerization initiator may be contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the solid content in the hard coating composition. When the content of the photopolymerization initiator is less than 0.1 parts by weight, the curing rate is slow. When the content of the photopolymerization initiator is more than 10 parts by weight, excessive cracking may occur in the hard coating layer.

In one embodiment of the present invention, the solvent can be used without limitation as long as it is used in the technical field. Specifically, alcohol-based solvents such as methanol, ethanol, isopropanol, butanol, and propylene glycol methoxy alcohol; Ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone and dipropyl ketone; Acetate-based solvents such as methyl acetate, ethyl acetate, butyl acetate and propylene glycol methoxyacetate; Cellosolves such as methyl cellosolve, ethyl cellosolve and propyl cellosolve; And hydrocarbons such as normal hexane, normal heptane, benzene, toluene and xylene. These solvents may be used alone or in combination of two or more.

The solvent may be included in an amount of 5 to 90 parts by weight, preferably 20 to 70 parts by weight, based on 100 parts by weight of the entire hard coating composition. When the amount is less than 5 parts by weight, the viscosity is high and workability is deteriorated. When the amount is more than 90 parts by weight, it is difficult to adjust the thickness of the coating film and drying irregularity may occur.

In addition to the above-mentioned components, the hard coating composition according to an embodiment of the present invention may further include components commonly used in the art, for example, leveling agents, ultraviolet stabilizers, heat stabilizers, and the like.

The leveling agent can be used to impart smoothness and coatability of a coating film when the composition is coated. Examples of the leveling agent include BYK-323, BYK-331, BYK-333, and BYK-333 manufactured by BYK Corporation, a leveling agent in the form of a commercially available silicone, a leveling agent in a fluorine form, and a leveling agent in the form of an acrylic polymer. TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, BYK- TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, FC-4430 and FC-4432 from 3M. The leveling agent may be used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the entire hard coating composition.

The ultraviolet stabilizer may be added for the purpose of shielding or absorbing ultraviolet rays to protect the adhesive, since the surface of the cured coating film is decomposed by continuous ultraviolet exposure to be discolored and crumbled. The ultraviolet stabilizer is classified into an absorbent, a quencher, and a hindered amine light stabilizer (HALS) according to the action mechanism. Depending on the chemical structure, it can be divided into Phenyl Salicylates, Benzophenone, Benzotriazole, Nickel Derivatives and Radical Scavenger. . In the present invention, there is no particular limitation as long as it is an ultraviolet stabilizer that does not significantly change the initial color of the coating film.

The heat stabilizer is a commercially applicable product, and it can be used either alone or in combination with a polyphenol as a primary heat stabilizer, a phosphite as a secondary heat stabilizer, and a lactone system.

The ultraviolet stabilizer and the heat stabilizer can be appropriately used at a level at which the ultraviolet curing property is not affected.

One embodiment of the present invention is directed to a hardcoat film formed using the hardcoat composition described above. The hard coating film according to an embodiment of the present invention is characterized in that a coating layer containing a cured product of the hard coating composition described above is formed on one side or both sides of the transparent substrate.

As the transparent substrate, any transparent polymer film can be used. The polymer film can be produced by a film-forming method or an extrusion method according to the molecular weight and the film production method, and can be used regardless of the commercially available transparent polymer film. Examples thereof include triacetyl cellulose, acetyl cellulose butyrate, ethylene- But are not limited to, vinyl acetate copolymer, propionyl cellulolose, butyryl cellulose, acetyl propionyl cellulose or a polyester, polystyrene, polyamide, polyether imide, polyacryl, polyimide, polyether sulfone, polysulfone, , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate , Polyethylene naphthalate , There may be mentioned a variety of transparent polymer substrate such as polycarbonate.

The thickness of the transparent substrate is not particularly limited, but may be 10 to 1000 탆, specifically 20 to 150 탆. If the thickness of the transparent base material is less than 10 탆, the strength of the film is lowered and the workability is deteriorated. If the thickness is more than 1000 탆, the transparency is decreased or the weight of the hard coating film is increased.

The hard coating film according to one embodiment of the present invention can be produced by applying the hard coating composition of the present invention to one side or both sides of a transparent substrate and curing to form a coating layer.

The hard coating composition according to an embodiment of the present invention may be coated on a transparent substrate by appropriately using a known method such as die coater, air knife, reverse roll, spray, blade, casting, gravure, microgravure, ) Is possible.

After the hard coating composition is applied to the transparent substrate, volatiles are evaporated at a temperature of 30 to 150 ° C for 10 seconds to 1 hour, more specifically for 30 seconds to 30 minutes, And cured. The irradiation amount of the UV light may be about 0.01 to 10 J / cm 2, and more specifically, about 0.1 to 2 J / cm 2.

At this time, the thickness of the formed coating layer may be specifically 2 to 30 탆, more specifically 3 to 20 탆. When the thickness of the coating layer is within the above range, an excellent hardness effect can be obtained.

One embodiment of the present invention relates to an image display apparatus provided with the above-mentioned hard coating film. For example, the hard coating film of the present invention can be attached to an image display device, particularly a window of a flexible display device.

The hard coating film according to one embodiment of the present invention can be used in reflective, transmissive, semi-transmissive LCD or various driving LCDs such as TN type, STN type, OCB type, HAN type, VA type and IPS type. The hard coating film according to one embodiment of the present invention can also be used in various image display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and an electronic paper.

Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples and Experimental Examples. It should be apparent to those skilled in the art that these examples, comparative examples and experimental examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Examples 1 to 3 and Comparative Example 1: Preparation of Hard Coat Composition

Hard coating compositions were prepared by mixing the components in the compositions shown in Table 1 below (unit: wt%).

Alkoxysilane compound 1 Alkoxysilane compound 2 Polysiloxane resin Urethane acrylic resin Inorganic nanoparticle Photopolymerization initiator additive solvent Example 1 68.5 10 One 0.5 20 Example 2 58.5 10 One 0.5 30 Example 3 68 10 One One 20 Comparative Example 1 68 10 One One 20

Alkoxysilane compound 1: 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shin-Etsu)

Alkoxysilane compound 2: 3-glycidoxypropyltrimethoxysilane (KBM-403, Shin-Etsu)

Polysiloxane resin: SP-3T (Shin-A & T)

Urethane acrylic resin: SUO1700B (Shin A & T)

Inorganic nanoparticles: MEK-AC-2140Z (Nissan chemical)

Photopolymerization initiator: Irgacure 250 (BASF)

Additives: Silclean 3700 (BYK)

Solvent: methyl ethyl ketone

Experimental Example 1:

The hard coating composition prepared in the above Examples and Comparative Examples was coated on one surface of an optical polyimide film (Mitsubishi Gas Chemical Co., Ltd., 100 占 퐉, L-3430) so as to have a thickness of 50 占 퐉, After drying, a hard coat film was prepared by curing the metal halide lamp at a light amount of 1.5J.

The physical properties of the prepared hard coating film were measured by the following method, and the results are shown in Table 2 below.

(1) Pencil Hardness

Pencil hardness was measured by applying a load of 1 kg using a pencil hardness tester (PHT, Kobo Scientific Co., Ltd.). The pencil was made five times per pencil hardness using Mitsubishi products. In case of 2 or more gypsum, it was judged to be defective and recorded as the maximum hardness determined as OK.

(2) Scratch 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) Adhesion

11 straight lines were drawn on the coated surface of the film at intervals of 1 mm to form 100 squares, and then peel test was performed three times using a tape (CT-24, Nichii Co., Ltd.). Three 100 squares were tested and the average was recorded. The adhesion was recorded as follows.

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 none of them were peeled off, 100/100 was recorded.

(4) Curl

A sample cut into a square shape 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-sided glass plate was measured at 25 DEG C and 50% As a measurement value.

(5) Mandrell

In order to evaluate the flexibility and the cracking property 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 to 20φ) The smallest diameter is indicated.

Example 1 Example 2 Example 3 Comparative Example 1 Pencil hardness 7H 7H 7H 2H Abrasion resistance S S S B Adhesiveness 100/100 100/100 100/100 80/100 curl 5mm 5mm 5mm 20mm Mandrell 3φ 3φ 3φ 18φ

As shown in Table 2, the hard coating films prepared using the hard coating compositions of Examples 1 to 3 according to the present invention were excellent in hardness, scratch resistance, adhesion, curl and crack resistance. On the other hand, the hard coat film prepared using the hard coat composition of Comparative Example 1 was found to be inferior in hardness, scratch resistance, adhesion, curl characteristic, or crack resistance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Do. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims (8)

An alkoxysilane compound having an epoxy group of the following formula (I) or a hard coating composition comprising a polysiloxane resin, an inorganic nanoparticle, a photopolymerization initiator and a solvent prepared by a sol-gel reaction of the alkoxysilane compound:
(I)
R ¹ _n Si (OR ² ) _4-n
Wherein R ¹ is an epoxy group, R ² is an alkyl group having 1 to 20 carbon atoms, and n is an integer of 1 to 3. The hard coating composition according to claim 1, wherein R ² is an alkyl group having 1 to 6 carbon atoms. The alkoxysilane compound according to claim 1, wherein the alkoxysilane compound having the epoxy group of Formula (I) is at least one selected from the group consisting of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane , 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. The hard-coating composition according to claim 1, wherein the polysiloxane resin is prepared by subjecting the alkoxysilane compound to a sol-gel reaction in the presence of a catalyst. The polysiloxane resin according to claim 1, wherein the polysiloxane resin produced by the sol-gel reaction of the alkoxysilane compound having the epoxy group of formula (I) or the alkoxysilane compound is contained in an amount of 50 to 90 parts by weight based on 100 parts by weight of the solid content of the hard coat composition Hard coating composition. A hardcoat film formed using the hardcoat composition according to any one of claims 1 to 5. An image display device comprising the hard coating film according to claim 6. A window of a flexible display device provided with a hard coating film according to claim 6.