KR20120077915A - Hard coating film - Google Patents

Abstract

PURPOSE: A hard coating film is provided to maintain pencil hardness of 3H or more even under film thickness of 10 micro or less by using inorganic nanoparticles of two or more kinds having different particle diameter each other. CONSTITUTION: A hard coating film comprises an ultraviolet-curable resin, a photoinitiator, two or more kinds selected from a group consisting of inorganic nanoparticles of which average particle diameter(D_50) are 5-15 nm, 16-30 nm and 30-100 nm, and comprises a hard coating layer of which pencil hardness is 3H or more. The inorganic nanoparticle is surface-treated by (meth)acrylate. The hard coating layer comprises inorganic nano particles of which average particle diameter(D_50) is 5-15 nm and 16-30 nm. The weight ratio of an inorganic nanoparticle with the average particle diameter(D_50) of 5-15 nm, and an inorganic nanoparticle with the average particle diameter(D_50) of 16-30 nm is 1:1-1:9.

Description

Hard coating film {Hard coating film}

The present invention relates to a hard coat film. More specifically, the present invention relates to a hard coating film having a different particle diameter and including two or more inorganic nanoparticles, so that pencil hardness of 3H or more can be maintained even with a coating film thickness of 10 μm or less and the curl is low.

The polarizer is generally used in which a cellulose resin film is bonded to both surfaces of a polarizer on a film made of polyvinyl alcohol or the like. Usually, a protective film is adhered to one base film for the purpose of preventing surface damage during transportation, and the other resin film has a multilayer structure in which an adhesive layer and a release film are laminated. Such a polarizing plate is used as a major component of a liquid crystal display device. In order to exhibit high durability in using such a polarizing plate under various environments, there is an increasing demand for high hardness hard coating products during polarization surface treatment.

In order to implement a conventional high hardness product, the coating thickness of the hard coating layer may be 10 μm or more to satisfy pencil hardness 3H or more. However, as the thickness of the coating film increases, the shrinkage during UV curing increases, which causes severe curling, which may cause breakage of the film in manufacturing the polarizer, and also has disadvantages in terms of manufacturing cost.

Therefore, it is necessary to develop a hard coating film having a hard coating layer which can satisfy high hardness, for example, pencil hardness of 3H or more, even with a coating film thickness of 10 μm or less, and less curling phenomenon.

It is an object of the present invention to provide a hard coating film that can realize high hardness, for example, pencil hardness 3H or more, even with a thickness of 10 μm or less.

Another object of the present invention is to provide a hard coating film with less curling while implementing a pencil hardness of 3H or more.

The hard coat film of the present invention is an ultraviolet curable resin; Photoinitiators; And an inorganic nanoparticle having an average particle diameter (D50) of 5-15 nm, 16-30 nm, and 30-100 nm, and may have a hard coating layer having a pencil hardness of 3H or more.

In one embodiment, the hard coat layer may include inorganic nanoparticles surface-treated with (meth) acrylate having an average particle diameter (D50) of 5-15nm and 16-30nm.

In one embodiment, the weight ratio of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm to inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm may be 1: 1 to 1: 9.

In one embodiment, the hard coating layer may include inorganic nanoparticles having an average particle diameter (D50) of 5-15nm and 30-100nm.

In one embodiment, the weight ratio of the inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm: the inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm may be 1: 1 to 1: 9.

In one embodiment, the hard coat layer may include inorganic nanoparticles having an average particle diameter (D50) of 5-15nm, 16-30nm and 30-100nm.

In one embodiment, the weight ratio of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm: inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm: inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm is 1 : 1 ~ 4: can be 1 ~ 5.

The present invention provides a hard coating film that can realize high hardness, for example, pencil hardness 3H or more, even with a thickness of 10 μm or less. In addition, the present invention provides a hard coating film with less curling while implementing a pencil hardness of 3H or more.

The hard coating film of the present invention may have a pencil hardness of 3H or more at a thickness of 10 μm or less, preferably 1-10 μm. In general, in order to realize a hard coating film having a high hardness, the thickness of the hard coating layer may be 10 μm or more, so that the pencil hardness may be 3H or more. However, as the thickness increases, the curling becomes more severe. However, the hard coating film of the present invention is characterized in that the pencil hardness can be more than 3H or more at a thickness of 10 μm or less, preferably 1-10 μm, and the curling is low.

Hereinafter, each component contained in a hard coat layer is explained in full detail.

Inorganic Nanoparticles

In the hard coating film of the present invention, the hard coating layer includes inorganic nanoparticles surface-treated with (meth) acrylate, but at least two inorganic nanoparticles having different particle diameters, preferably three or more, and more preferably It may include three species.

Inorganic nanoparticles surface-treated with (meth) acrylate are commonly used to increase the surface hardness in the hard coat layer. However, if the inorganic nanoparticles are used arbitrarily to increase the surface hardness, the thickness of the hard coating layer may become thick, which may cause curling during UV curing.

In the present invention, using inorganic nanoparticles having different particle diameters, by adjusting the particle diameter and content ratio of the inorganic nanoparticles, it is characterized in that not only improve the pencil hardness, but also no curling phenomenon.

When using two or more kinds of inorganic nanoparticles in the hard coating layer of the present invention, two or more kinds selected from the group consisting of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm, 16-30 nm and 30-100 nm may be used. .

In one embodiment, a mixture of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm and inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm may be used. In this case, the weight ratio of the inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm: the inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm may be 1: 1-1: 9. Within this range, the pencil hardness can be increased without increasing the thickness of the hard coat layer and there is no curling phenomenon. Preferably, it may be 1: 2-1: 5.

In another embodiment, a mixture of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm and inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm may be used. In this case, the weight ratio of the inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm to the inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm may be 1: 1-1: 9. Within this range, the pencil hardness can be increased without increasing the thickness of the hard coat layer and there is no curling phenomenon. Preferably, it may be 1: 2-1: 5.

In another embodiment, a mixture of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm, inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm, and inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm may be used. Can be. In this case, the inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm: Inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm: Inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm have a weight ratio of 1: 1 to 4 Can be from 1 to 7. Within this range, the pencil hardness can be increased without increasing the thickness of the hard coat layer and there is no curling phenomenon. Preferably, 1: 2-3: 6-7 .

Inorganic nanoparticles surface-treated with (meth) acrylate used in the present invention have uniform self-dispersion characteristics, have a stable dispersion characteristics without scattering the transmitted light, there is no entanglement between particles, high transparency and low turbidity .

Such inorganic nanoparticles can be used that 3-50% of the total surface area of the inorganic nanoparticles surface-treated with a (meth) acrylate compound. Within this range, it has uniform dispersibility and transparency.

The inorganic nanoparticles are not particularly limited and may be organic particles, inorganic particles or a mixture thereof. Preferably, at least one of SiO 2, Al 2 O 3, CaCO 3, TiO 2, and the like may be used.

Inorganic nanoparticles may be included in a state where they are not surface treated, but those surface-treated with (meth) acrylate may be used.

The inorganic nanoparticle surface treating agent may be one or more selected from the group of silane coupling agents consisting of vinyl, epoxy, methacrylooxy, amino, and the like, but is not limited thereto. Surface treatment of inorganic nanoparticles with a (meth) acryloxy silane coupling agent for chemical bonding with an acrylate resin is a common method.

The surface treatment of the inorganic nanoparticles with (meth) acrylate can be carried out by conventional methods. For example, it may be surface treated through chemical bonding between inorganic nanoparticles and (meth) acrylate. For the above chemical bonding, the inorganic nanoparticles may be pretreated with one or more silane coupling agents selected from the group consisting of vinyl, epoxy, (meth) acryloxy and amino.

The inorganic nanoparticles surface-treated with (meth) acrylate may be included in an amount of 10-70% by weight based on solids in the hard coating layer including an ultraviolet curable resin, inorganic nanoparticles surface-treated with (meth) acrylate, and a photoinitiator. Within this range, the surface hardness does not decrease, there is no curling phenomenon, and the turbidity of the film coating film may not increase. Preferably it may be included in 20-50% by weight.

The hard coating layer of the present invention may include an ultraviolet curable resin and a photoinitiator in addition to the inorganic nanoparticles.

UV curable resin

UV-curable resins are resins having acrylate-based functional groups, for example urethane resins, polyester resins, polyether resins, acrylic resins, epoxy resins, alkyd resins, spiro acetal resins, polybutadiene resins, polythiol polyene resins, And (meth) acrylate resins of polyfunctional compounds such as polyhydric alcohols. Preferably, urethane resin can be used.

Specific examples include ethylene glycol diacrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acryl Polyester (meth) acrylates obtained by esterifying polylate poly (meth) acrylates, di (meth) acrylates of bisphenol A-diglycidyl ether, polyhydric alcohols and polyhydric carboxylic acids, and their anhydrides and acrylic acids , Polysiloxane polyacrylate, urethane (meth) acrylate, pentaerythritol tetramethacrylate and glycerin trimethacrylate, aromatic urethane, cycloaliphatic urethane and urethane acrylate resin may be at least one selected from the group consisting of However, it is not limited to these.

In addition, the ultraviolet curable resin having an acrylate-based functional group may include an acrylate compound having a hydroxy group.

The acrylate compound which has such a hydroxyl group is oligomers, such as 2-hydroxyethyl acrylate oligomer, 2-hydroxypropyl acrylate oligomer, pentaerythritol triacrylate oligomer, 2-hydroxyethyl (meth) acrylate, 2- Monomers such as hydroxypropyl (meth) acrylate, caprolactone (meth) acrylate, 2,3-dihydroxypropyl (meth) acrylate, and 4-hydroxymethylcyclohexyl (meth) acrylate can be used. .

In addition, the ultraviolet curable resin may be a resin containing fluorine, such as a fluorine-containing epoxy acrylate and a fluorine-containing alkoxysilane. Specific examples include 2- (perfluorodecyl) ethyl (meth) acrylate, 3-perfluorooctyl-2-hydroxypropyl (meth) acrylate, 3- (perfluoro-9-methyldecyl) -1 , 2-epoxypropane, (meth) acrylic acid-2,2,2-trifluoroethyl, (meth) acrylic acid-2,2,2-trifluoromethyl, 3,3,3-trifluoropropyl, and the like However, it is not limited to these.

The ultraviolet curable resin may be included in an amount of 30 to 89% by weight based on the solid content of the hard coat layer including the ultraviolet curable resin, inorganic nanoparticles surface-treated with (meth) acrylate and a photoinitiator. Within this range, the pencil hardness of the hard coat layer is good and the scratch resistance is good and no curling occurs. Preferably, it may be included in 50-80% by weight.

Photoinitiator

A photoinitiator can use the photoinitiator well-known conventionally used conventionally. For example, although a benzophenone type compound like 1-hydroxycyclohexyl phenyl ketone can be used, it is not limited to these.

The photoinitiator may be included in an amount of 0.1-1.0 wt% based on solids in the hard coating layer including the ultraviolet curable resin, the inorganic nanoparticles surface-treated with (meth) acrylate, and the photoinitiator. Within this range, it satisfies the pencil hardness and the scratch resistance without uncuring. Preferably it may be included in 0.3-0.7% by weight.

The hard coat layer of the present invention may further include a polyfunctional monomer.

Multifunctional Monomer

The polyfunctional monomer may be a monomer which is bifunctional or higher, preferably 6 or higher. For example, the polyfunctional monomer may be at least one selected from the group consisting of a hydroxyl group-containing polyfunctional (meth) acrylate and a fluorine-modified polyfunctional (meth) acrylate.

The hydroxyl group-containing polyfunctional (meth) acrylates include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol diacrylate, 1, 6-hexanediol diacrylate, neopentyl diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacryl Latex, pentaerythritol hexaacrylate, dipentaerythritol hexaacrylate, bisphenol A diacrylate, trimethylol propane triacrylate, novolac epoxy acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol Di (meth) acrylate, 1,6-hexanedioldi (meth) acrylate to be at least one selected from the group consisting of However, it is not limited thereto.

When the polyfunctional monomer is included, the UV-curable resin is included in the hard coat layer in 35-59% by weight, the polyfunctional monomer is contained in 10-30% by weight, the inorganic nanoparticles are included in 30-50% by weight, Photoinitiator may be included in 0.1-5% by weight. Within this range, the pencil hardness and scratch resistance of the hard coat layer may be good. Preferably it may be included in 10-20% by weight.

The hard coating layer of the present invention is conventional, such as photosensitizers, photosensitizers, polymerization inhibitors, leveling agents, wetting properties improvers, surfactants, plasticizers, ultraviolet absorbers, antioxidants, antistatic agents, silane coupling agents, inorganic fillers, antifoaming agents and the like It may further include an additive. These can be used individually or in mixture of 2 or more types.

The hard coating film of the present invention may include a base film and the hard coating layer, the hard coating layer is formed on the base film.

The base film may be, for example, at least one selected from the group consisting of cellulose ester resins, polyester resins, polycarbonate resins, norbornene resins, polyarylate resins, and polysulfone resins. Preferably, the triacetyl cellulose film which is acetyl cellulose resin can be used.

The thickness of the base film may be 80 μm, and the thickness of the hard coating layer may be 10 μm or less, preferably 3-8 μm, but is not limited thereto.

Hard coating film of the present invention may be mounted to serve as a protective and support of the polarizer in the polarizing plate.

Method for producing a hard coating film comprises the steps of preparing a composition for forming a hard coating layer; Applying the composition to a base film; Drying the composition; And curing the composition.

In the step of preparing a composition for forming a hard coating layer, the composition is prepared by adding each component included in the hard coating layer of the present invention. The content of each component is as above-mentioned. In the composition, a solvent having solubility and swellability in the ultraviolet curable resin may be used.

The solvent may be a solvent that is soluble and swellable in the ultraviolet curable resin. Specific examples include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, diacetone alcohol or polyalcohol as ketones, methyl cellosolve, ethyl cellosolve, butyl cellosolve or cellosolve acetate, ester as ethers. Examples include methyl acetate, ethyl acetate or butyl acetate, chloroform, methylene chloride or tetrachloroethane as halogenated hydrocarbons, nitromethane, acetonitrile, N-methylpyrrolidone, N, N-dimethylformamide as nitrogen-containing compounds, These can be used 1 type or in mixture of 2 or more types.

In the applying step, the prepared composition for forming a hard coat layer is applied on a base film. As a method of applying the composition to the base film, a bar coating method, a knife coating method, a gravure coating method, a micro gravure coating method, a slot die coating method, or the like may be used.

In the drying step, the applied composition for forming a hard coat layer is dried to remove the solvent.

In the ultraviolet curing step, a hard coating layer is formed on the base film by curing the dried hard coating layer-forming composition by irradiation with ultraviolet rays. Ultraviolet lamps include high pressure mercury lamps, metal halide lamps, xenon lamps, and microwave electrodeless lamps. The wavelength range is 250-360 nm, and the light amount may be 180-250 mJ / cm 2, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

Specific specifications of the components used in the following examples and comparative examples are as follows.

1.UV curable resin: HX-920UV (Kyoeisha)

2. Multifunctional monomer: DPHA (SK cytec)

3. Inorganic nanoparticles surface-treated with (meth) acrylate

Optisol-SST650U (average particle size: 12nm, Ranco)

Optisol-SST350T1 (average particle size: 22nm, Ranco)

Optisol-SST2350T3 (average particle size: 50nm, Ranco)

4. Photo Initiator: Irgacure 184 (Ciba Specialty)

5. Base film: Triacetyl cellulose film (thickness: 80㎛, Normal TAC, Hyosung)

Example 1-3 Preparation of Hard Coating Film

As the solvent, 45 parts by weight of the ultraviolet curable resin, 14.9 parts by weight of the polyfunctional monomer, and the average particle diameter (D50) (nm) and the content (parts by weight) of the inorganic nanoparticles in 10 g of ethyl acetate and 20 g of methyl ethyl ketone are shown in Table 1 below. After mixing the content and stirred for 20 minutes, 0.1 part by weight of a photoinitiator was added and stirred for 10 minutes to prepare a composition for forming a hard coat layer.

The obtained composition was coated on a triacetyl cellulose film by using a # 16 meyer bar coater (7 μm) and dried at 80 ° C. for 40 seconds. After drying, a high-pressure mercury lamp was irradiated with ultraviolet light at a light amount of 180 mJ / cm 2 to cure, thereby preparing a hard coating film having a thickness of 7 μm.

Comparative Example 1-2: Preparation of Hard Coating Film

Except for changing the content of the component in Example 1 to the content shown in Table 1 was carried out the same method to prepare a hard coating film of 7㎛ thickness. Units of content in Table 1 are parts by weight.

Inorganic Nanoparticles 1 Inorganic Nanoparticles 2 Inorganic Nanoparticles 3 Average particle diameter content Average particle diameter content Average particle diameter content Example 1 12nm 20 22 nm 20 50 nm - Example 2 12nm 10 22 nm 15 50 nm 15 Example 3 12nm 10 22 nm 30 50 nm - Comparative Example 1 12nm 40 - - - - Comparative Example 2 12nm - 22 nm 40 50 nm -

Experimental Example: Measurement of Physical Properties of Hard Coating Film

The physical properties described in Table 2 below were measured for the hard coat films prepared in Examples and Comparative Examples, and the results are shown in Table 2 below.

<Measurement method of physical property>

1. Pencil hardness: Using a pencil hardness tester (Shinto Scientific, Heidon) with a Mitsubishi evaluation pencil (UNI) 5 times at a load of 500kg / cm2, 5mm at a speed of 0.5mm / sec, and then the number of wounds Pencil hardness was evaluated.

2. Curing: A 100 mm x 100 mm film sample was prepared, and the height (H) of the highest of the four corners at the bottom was measured.

3. Scratch resistance: Using steelwool (# 0000), after rubbing 1000g load, 50mm / sec speed, 100mm in 10 round trips, the number of scratches was checked and the scratches were evaluated.

4. Rainbow (interference pattern) test: In order to prevent back reflection, black tape was attached to the opposite surface of the hard coating layer, and visual inspection was performed under the three wavelength fluorescence on the surface of the hard coating layer, and evaluated as the following evaluation criteria.

<Rainbow evaluation criteria>

1: No rainbow in all directions.

2: weakly occurring

3: strongly occur

Pencil hardness Curling (mm) Scratch resistance Rainbow Example 1 3.6H 22 No scratch One Example 2 3.6H 18 No scratch One Example 3 3.0H 30 No scratch One Comparative Example 1 2.0H Not measurable 10 lines of scratch One Comparative Example 2 2.0H Not measurable 10 lines of scratch One

As shown in Table 2, the hard coating film of the present invention came out with a pencil hardness of 3.6H even in the coating film thickness of 7㎛, it can be seen that there is almost no curling. On the other hand, Comparative Examples 1 and 2 containing only one type of inorganic nanoparticles having an average particle diameter of 12 nm were very low compared to the present invention, and pencil curling was remarkably generated and scratch resistance was not good.

Claims (15)

Ultraviolet curable resins;
Photoinitiators; And
Including at least two kinds selected from the group consisting of inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm, 16-30 nm and 30-100 nm
Hard coating film having a hard coating layer having a pencil hardness of 3H or more.
The hard coating film of claim 1, wherein the inorganic nanoparticles are surface treated with (meth) acrylate.
The hard coating film of claim 1, wherein the hard coating layer comprises inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm and 16-30 nm.
The method of claim 3, wherein the weight ratio of the inorganic nanoparticles having an average particle diameter (D50) of 5-15nm: inorganic nanoparticles having an average particle diameter (D50) of 16-30nm is 1: 1 to 1: 9. Coated film.
The hard coating film of claim 1, wherein the hard coating layer comprises inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm and 30-100 nm.
The method of claim 5, wherein the weight ratio of inorganic nanoparticles having an average particle diameter (D50) of 5-15nm: inorganic nanoparticles having an average particle diameter (D50) of 30-100nm is 1: 1 to 1: 9. Coated film.
The hard coating film of claim 1, wherein the hard coating layer comprises inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm, 16-30 nm, and 30-100 nm.
The weight ratio of inorganic nanoparticles according to claim 7, wherein the inorganic nanoparticles having an average particle diameter (D50) of 5-15 nm: inorganic nanoparticles having an average particle diameter (D50) of 16-30 nm: inorganic nanoparticles having an average particle diameter (D50) of 30-100 nm. Is 1: 1 to 4: Hard coating film characterized in that 1 to 5.
The hard coating film of claim 1, wherein the inorganic nanoparticles are at least one member selected from the group consisting of SiO 2, Al 2 O 3, CaCO 3, and TiO 2.
The hard coating film of claim 1, wherein the inorganic nanoparticles are included in an amount of 30 to 89 wt% based on solids in the hard coating layer.
The method of claim 1, wherein the UV-curable resin is contained in 10 to 70% by weight, the inorganic nanoparticles are contained in 30 to 89% by weight, the photoinitiator is 0.1 to 10% by weight of the hard coating layer Hard coating film, characterized in that it is included.
The hard coating film of claim 1, wherein the hard coating layer has a thickness of 1-10 μm.
According to claim 1, wherein the hard coating layer is a hard coating film, characterized in that the thickness of 3-8㎛.
The hard coating film of claim 1, wherein the hard coating layer further comprises a polyfunctional monomer.
15. The method of claim 14, wherein the UV-curable resin in the hard coat layer is contained in 35-59% by weight, polyfunctional monomer is contained in 10-30% by weight, inorganic nanoparticles are contained in 30-50% by weight, Hard-coating film, characterized in that the photoinitiator is contained in 0.1-5% by weight.