WO2018110949A1 - Optical film and image display device comprising same - Google Patents

Abstract

The present invention relates to an optical film and an image display device comprising same, the optical film showing excellent optical properties such as low glossiness and reflectance and an appropriate level of haze properties. The optical film comprises: a light transmissive base film; an anti-glare layer comprising a binder, which comprises a (meth)acrylate cross-linked polymer, micron (μm)-scale organic fine particles, which are dispersed on the binder, and nano (nm)-scale inorganic fine particles which are dispersed on the binder; and a low refractive layer formed on the anti-glare layer and comprising a binder resin, which comprises a (co)polymer of a photopolymerizable compound, and hollow silica particles which are dispersed on the binder resin, wherein the organic and inorganic particles show predetermined particle diameter distribution, refractive index differential and content range.

Description

 [Name of invention]

 Optical film and image display device including the same

 Technical Field

 Cross Citation with Related Application (s)

 This application claims the benefit of priority based on Korean Patent Application No. 10-2016-0168857 of December 12, 2016 and Korean Patent Application No. 10-2017-0169718 of December 1, 2017, and the Korean Patent Application All content disclosed in these references is included as part of this specification.

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film exhibiting excellent glossiness and reflectance, and excellent optical properties such as an appropriate level of haze properties, and an image display device including the same.

 Background Art

 In an image display device such as an organic electroluminescent element (OELD) or a liquid crystal display element (LCD), it is required to prevent a decrease in contrast due to reflection of external light or reflection of an image or a decrease in visibility. To this end, optical laminated films such as antireflection films are formed on the surface of an image display device in order to reduce image reflection or reflection using light scattering or optical interference.

 For example, in a liquid crystal display element etc., the optical laminated film containing an anti-glare layer has been generally formed before. The anti-glare layer mainly includes a binder and fine particles contained in the binder, and these fine particles are usually formed so that a part of the anti-glare surface protrudes from the binder surface. That is, in the anti-glare layer, the fine particles protruding from the surface of the binder can control light scattering / reflection, etc. to suppress the deterioration of visibility of the image display device.

However, in the case of the previously known antiglare and optical film, the glossiness of the surface is often high, and the reflection of external light is often difficult to be suppressed. Could not be suppressed. Moreover, in the previous anti-glare layer and the optical film, proper control of surface irregularities was difficult, so that the glare defects due to irregular irregularities often appeared, and scattering or reflection of external light, etc. could not be properly controlled. This also became one factor of lowering optical characteristics such as haze characteristics or glossiness of the optical film. As a result, the existing anti-glare layer and the optical film are not enough optical properties, such as haze characteristics, reflectance or glossiness, there is a disadvantage that does not sufficiently improve the contrast / visibility of the image display device, which is due to the optical properties of the optical film Further improvements are constantly being requested.

 [Detailed Description of the Invention]

 [Technical problem]

 Accordingly, the present invention is to provide an optical film exhibiting excellent glossiness and reflectance and excellent optical properties such as an appropriate level of haze properties.

 This invention also provides the image display apparatus containing the said optical film.

 [Technical solution]

 The present invention is a light-transmissive base film;

 An antiglare layer comprising a binder including a (meth) acrylate-based crosslinked polymer, an organic fine particle of a micron (1) scale dispersed on the binder, and an inorganic fine particle of a nano (nm) scale dispersed on the binder; And

 A low refractive layer formed on a Singapore antiglare layer and comprising a binder resin containing a (co) polymer of a photopolymerizable compound and hollow silica particles dispersed in the binder resin; Including,

When the total average particle diameter of the organic and inorganic fine particles is D average, and the organic and inorganic fine particles are arranged in descending order from the smallest particle size, the particle diameter of the fine particles corresponding to the cumulative 25 number ⁰ /. Is D25, and the cumulative 75 number ⁰ When the particle size of the particles corresponding to / / is defined as D75, (D75-D25) / D average is 0.25 or less,

 The absolute value of the difference in refractive index between the organic and inorganic fine particles and the binder is 0.01 to 0.25,

The total amount of the organic and inorganic fine particles is 1 to 30 parts by weight _^0/0 of the total amount of the anti-glare layer,

An optical film having a 60 ^° glossiness deviation value of 3% to 10% and a total haze of 1 to 5%.

In addition, the present invention is a light-transmitting base film; An antiglare layer comprising a binder including a (meth) acrylate-based crosslinked polymer and a plurality of light-transmitting fine particles of a sub-micron (sub-// m) scale dispersed on the binder; And

 A low refractive layer formed on the antiglare layer and including a binder resin containing a (co) polymer of a photopolymerizable compound and hollow silica particles dispersed in the binder resin; Including

The average particle diameter of the light-transmitting fine particles is D average, and when the light-transmitter fine particles are arranged in descending order from the smallest particle size, the particle size of the fine particles corresponding to the cumulative 25 number ⁰ /. Is D25, and the cumulative 75 number ⁰ /. When the particle diameter of the corresponding fine particles is defined as D75, the (D75-D25) / D average is 0.04 to 0.15,

 The absolute value of the refractive index difference of the light-transmitting fine particles and the binder is 0.02 to 0.25,

The total content of the transparent fine particles is 1 to 30 parts by weight _^0/0 of the total amount of the anti-glare layer,

 Reflectance is 0.5% to 2.5%,

An optical film having a 60 ^° glossiness deviation value of 3 to 10% and a total haze of 1 to 5%.

The invention also provides the optical _. An image display device comprising a film is provided. Hereinafter, an optical film and an image display device including the same according to embodiments of the present invention will be described.

 As used herein, micron () scale refers to having a particle size or particle size of less than 1 mm, ie, less than 1000, and nano (nm) scale refers to particles less than 1 η, that is, less than 1000 nm. Refers to having a size or particle diameter, and sub-Am scale refers to having a particle size or particle size of the micron scale or the nano scale.

In addition, a photopolymerizable compound is collectively called a compound which causes crosslinking, hardening, or polymerization reaction when light is irradiated, for example, when visible light or an ultraviolet ray is irradiated. In addition, (meth) acryl [(meth) acryl] is acryl and methacryl It is meant to include both.

 In addition, a (co) polymer is meant to include both co-polymers and homo-polymers.

 In addition, silica hollow particles are silica particles derived from a silicon compound or an organosilicon compound, and mean particles having a void space on the surface and / or inside of the silica particles. According to one embodiment of the invention, a transparent substrate film;

 An antiglare layer comprising a binder containing a (meth) acrylate-based crosslinked polymer, an organic fine particle having a micron (1) scale dispersed on the binder, and a nano (nm) scale inorganic fine particle dispersed on the binder. ; And

 A low refractive layer formed on the antiglare layer and comprising a binder resin containing a (co) polymer of a Guam polymerizable compound and hollow silica particles dispersed in the binder resin; Including,

The average particle diameter of the organic and inorganic fine particles is D average, and when the organic and inorganic fine particles are arranged in descending order from the smallest particle size, the particle diameter of the fine particles corresponding to the cumulative 25 number ⁰ /. Is D25, and the cumulative 75 number ⁰ When the particle diameter of the fine particles corresponding to / ₀ is defined as D75, the (D75-D25) / D average is 0.25 or less,

 The absolute value of the refractive index difference between the organic and inorganic fine particles and the binder is 0.01 to 0.25,

The total amount of the organic and inorganic fine particles is 1 to 30 parts by weight of the total amount of the anti-glare layer _^0/0, and '

An optical film having a 60 ^° glossiness deviation value of 3% to 10% is provided.

 According to the experimental results of the inventors of the present invention, in the antiglare layer containing the organic and inorganic fine particles dispersed in the (meth) acrylate-based binder, by controlling the particle size distribution of the organic and inorganic fine particles to an appropriate level, (D75-D25) It is possible to provide an anti-glare layer and an optical film having excellent anti-glare properties by controlling the value of the / D average is 0.25 or less, or 0.04 to 0.15, and controlling the binder composition and the difference between the binder and the refractive index of the fine particles. Confirmed.

This is because the particle size distribution control is uniform Since the size of the irregularities protruding to the surface of the antiglare layer can be controlled uniformly and appropriately, the haze characteristics and glossiness of the antiglare layer can be adjusted to a desirable range. In addition, by controlling the difference between the refractive index of the binder and the fine particles, it is possible to effectively suppress scattering or reflection of external light, thereby providing an antiglare layer and an optical film having excellent antiglare characteristics and optical characteristics. If the particle size distribution range is out of the above-described range or out of the difference in refractive index, the variation in haze characteristics of the optical film may be severe, or the glossiness may be increased, thereby greatly reducing the optical characteristics / anti-glare characteristics.

In some embodiments the optical film has a total content of the organic and inorganic fine particles to be contained in the anti-glare layer, for example, 1 to 30 parts by weight ⁰ /., Or 2 to 20 parts by weight _^0/0, or from 3 to 10 wt. ⁰ /. Or 3 to 5 weight ⁰ /. As a result, it was confirmed that the optical properties / anti-glare properties of the optical film can be further improved. It may not be controlled properly and the anti-glare property may be greatly reduced. On the contrary, if the total content of the fine particles is too large. The refraction of the transmitted image light may increase to significantly reduce the image sharpness of the optical film.

 In addition, the optical film of the embodiment includes a specific binder composition described below, and specifically, a binder may be formed using a compound having 3 to 6 functionalities and a compound having 10 or more functionalities. As a result, the optical properties of the binder can be optimized and at the same time the refractive index difference with the above-mentioned fine particles can be properly controlled to optimize the optical properties / anti-glare properties such as haze or glossiness of the optical film.

 In addition, the optical film of the embodiment further comprises a hollow silica particle-containing low refractive layer formed on the anti-glare layer. By the formation of such a low refractive layer, the external light reflection of the optical film can be further suppressed, whereby the optical properties of the optical film can be further improved.

As described above, the optical film of one embodiment optimizes the configuration of the antiglare layer, forms a low refractive layer, and has excellent optical and antiglare characteristics such as low glossiness, glossiness variation and reflectance, and an appropriate level of haze characteristics. Can be represented. Hereinafter, the optical film of one embodiment will be described in detail for each element.

 The optical film of the embodiment includes at least a light transmissive base film exhibiting light transmittance to visible light, as a representative example of a cellulose ester base film, a polyester base film, a poly (meth) acrylate base film or It may include a polycarbonate-based substrate film. More specific examples of such a transparent base film, for example, triacetyl cellulose (TAC) film, polyethylene terephthalate (PET) base film, polyethylene naphthalate (PEN) base film, polyacrylate ( PA) film, a polycarbonate (PC) base film, or a polymethacrylate (PMMA) base film, etc. can be mentioned, In addition, any resin film known to be applicable as a base film of an optical film can also be used. Of course.

 In addition, in consideration of the excellent mechanical properties of the base film, water resistance, and the excellent optical properties of the optical film of one embodiment, the light-transmitting base film has a thickness of 20 to 500, or 30 to 200 ι, or 40 to 150 It may be a film having a.

 In addition, the optical film of one embodiment includes an antiglare layer formed on the base film. As described above, by controlling the refractive index and the binder refractive index difference, the particle size distribution and the content range of the fine particles contained in the anti-glare layer, it is possible to greatly improve the anti-glare characteristics and optical characteristics of the anti-glare layer and optical film have.

In such antiglare, the binder may be a crosslinked (co) polymer of a polyfunctional (meth) acrylate-based compound having a trifunctional or higher (meth) acrylate-based functional group. In a more specific example; As a polyfunctional (meth) acrylate type compound which has the said trifunctional or more than (meth) acrylate group, the (meth) acrylate type compound of 3-6 functional monomolecular form, and / or (meth) acrylate of 10 or more functionalities Polyurethane-based polymers having polyfunctional groups, poly (meth) acrylic polymers or polyester-based polymers may be used together. By the composition of such a binder, the difference in refractive index of the binder and the refractive index with the fine particles can be controlled to a more appropriate level. Moreover, it can contribute to maintaining the haze characteristic of the said glare-proof layer and an optical film at an appropriate level, and to improve image sharpness more. If only 3 to 6 functional monomolecular (meth) acrylate-based compounds are used, the haze characteristics may be out of an appropriate range, or the image sharpness may be lowered, and further, the optical characteristics of the antiglare layer may be lowered. This makes it difficult to achieve low glossiness and its deviation value.

 Specific examples of the (meth) acrylate-based compound of the 3-6 functional monomolecular form include a monomolecular compound having an aromatic ring with a (meth) acrylate-based functional group having a molecular weight of 3-6 (eg, UA-306T and the like used in the following examples), tri (meth) acrylate or trialkylolpropane tri (meth) acrylate, and the like.

 And as a polyurethane polymer, a poly (meth) acrylic polymer, or a polyester polymer which has the (meth) acrylate type functional group of said .10 functional earings, a polyurethane polymer, a poly (meth) acrylic polymer, or a polyester type Of polymers: polymers having an average of 10 to 80 in the backbone, and an average of 10 to 50 (meth) acrylate-based functional groups bonded to the main chain may be used, and the polymer may have a weight average molecular weight of 1000 to 200000. have.

 Moreover, the (methacrylate type compound of the said 3-6 functional monomolecular form, and the polymer which has the said (meth) acrylate type functional group of 10 or more functionalities) are the weight ratio of 1: 1-10: 1, for example, Or in a weight ratio of 2: 1 to 5: 1.

 By using the above-described composition to obtain a binder in the form of a crosslinked (co) polymer, the refractive index of the binder is controlled to, for example, 1.50 to 1.60, or 1.50 to 1.54, or 1.51 to 1.53 in an appropriate range. It is possible to more effectively control the appropriate refractive index difference with the fine particles included in the layer, and further improve the haze characteristics, image sharpness, glossiness, and variation of the antiglare layer and the optical film.

On the other hand, in the anti-glare layer, a plurality of light-transmitting fine particles having a sub-micron scale dispersed on a binder, for example, a micron scale Organic fine particles and inorganic fine particles on a nano (nm) scale. Such light-transmitting fine particles have a refractive index such that the absolute value of the refractive index difference from the binder described above is 0.01 to 0.25, black is 0.02 to 0.25, or 0.02 to 0.10, so that the antiglare layer has low glossiness, appropriate haze characteristics and excellent anti-glare. Can exhibit characteristics.

 As the organic fine particles, all resin particles previously known to be usable for antiglare and the like can be used without particular limitation, and specific examples thereof include polystyrene resin, poly (meth) acrylate resin or poly (meth) acrylate. Resin microparticles | fine-particles containing -CO-styrene-type copolymer resin are mentioned.

 The organic fine particles may be, for example, spherical particles having a particle diameter of 1 to 5, black to 1.5 to 4, and may have a refractive index of 1.5 to 1.57, or 1.51 to 1.56, or 1.53 to 1.56.

As the inorganic fine particles, metal oxide fine particles containing silica, alumina, zirconia or titania may be used, for example, as spherical particles having a particle diameter of 10 nm to 300 nm and black to 50 to 200 nm _; 1 to 175, or 1.4 to: 1.65, black may be one having a refractive index of 1.42 to 1.48, or 1.42 to 1.45.

 The light-transmitting fine particles including the organic / inorganic fine particles described above may have a uniform particle size distribution as described above, and thus, the size of the irregularities protruding to the antiglare surface is uniformly and appropriately controlled so that The haze property or glossiness can be adjusted to a preferred range, and as a result, the anti-glare layer and the optical film of one embodiment can exhibit excellent anti-glare properties / optical properties.

More specifically, the D average of the light-transmitting fine particles may be from 1.7 / m to 1.8 jwu to 2.2, the D25 may be 1.5 / 2.1 μηι, or 1.8 ᅳ I to 2.0, D75 is 1.9 IM to 2.5, or 1.9 ^ πι to 2.2. As a result, the value of the (D75-D25) / D average is controlled to 0.25 or less, or 0.04 to 0.15, so that the optical film of one embodiment may exhibit excellent optical properties. Then, the light-transmitting particle, for example, the above-described organic and inorganic fine particles are those of the total amount of the plurality of types, for example, relative to the total amount of the anti-glare layer, 1 to 30 parts by weight _^0/0, black 2 to 20 parts by weight _^0/0, the black is from 3 to 10 parts by weight _^0/0, or from 3 to

5 weight can be controlled to an appropriate level of ⁰ /. The organic fine particles and the inorganic fine particles may be used in a weight ratio of 4: 1 to 1: 2. As already described above, is adjusted to a suitable range of content of each of the transparent fine particles ^i, is one embodiment the optical film can exhibit a more excellent optical properties, such as. If the content range of the fine particles is out of an appropriate range, the surface irregularities on the antiglare layer may not be properly implemented, so scattering / reflection of external light may not be properly controlled, the antiglare characteristics may be deteriorated, or the refraction of the light may increase, resulting in an image of the optical film. Sharpness can be greatly reduced.

 In addition, the anti-glare layer may have a thickness of 1 to 10 / zm, or 2 to 8, wherein each of the above-described fine particles may be dispersed in the anti-glare layer or may suppress reflection or scattering of external light in a state where at least a portion thereof protrudes. have.

The anti-glare layer formed to have the composition and thickness described above and the particle size distribution of the light-transmitting fine particles can have excellent anti-glare characteristics by properly scattering or reflecting external light, and low. It can exhibit excellent optical properties such as glossiness and reflectance and appropriate haze properties. The excellent optical properties of such an antiglare layer can be defined by low glossiness / reflectivity of the surface, haze characteristics, and the like. For example, the anti-glare layer and the optical film may have a half rate of 0.5% to 2.5%, or 0.7% to 2.0%, 60 ^° gloss of 45% to 70%, and black to 50% to 65%. , or 50% and may be as 60%, the 60 ^° by a gloss measuring 10 [(maximum measured value - minimum measured value) / average value] 60 ^°, which is calculated by the formula of glossiness of 3% deviation values To 10%, or 3% to 8%, or 5% to 8%.

 In addition, the antiglare layer and the optical film may maintain an appropriate level as the total haze is 1 to 5%, or 2 to 4%, or 2.5 to 3.5%. When the total haze is too high, it is obvious that the optical properties are deteriorated. Even when the total haze value is too low, the external reflection image is not scattered and is visible, so that the visibility and image sharpness of the screen may be deteriorated.

On the other hand, the anti-glare layer has a composition as described above already It may be formed by dissolving in a composition containing a photopolymerizable compound, a photoinitiator, and an organic solvent including a (meth) acrylate-based compound.

 In such compositions, conventionally known photoinitiators can be used as the photoinitiator without great limitation. Examples of the photoinitiator are selected from 1-hydroxycyclohexylphenyl ketone, benzyl dimethyl ketal, hydroxydimethylacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin butyl ether. One single or two or more combinations.

 In this case, the photoinitiator may be added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the photopolymerizable compound of the (meth) acrylate compound. When the photoinitiator is included in less than 0.1 parts by weight based on 100 parts by weight of the photopolymerizable compound, sufficient photocuring may not occur by ultraviolet irradiation, and when included in excess of 10 parts by weight based on 100 parts by weight of the photopolymerizable compound, The adhesion of the antiglare layer and the base film may be lowered. Furthermore, when the photoinitiator is included in an excessively large content, the antiglare layer and the optical film including the same may be yellowed by the non-reflective initiator over time, thereby decreasing the optical / characteristic of the optical film.

 In addition, the composition may further comprise an organic solvent. When such an organic solvent is added, there is no limitation in the constitution, but in consideration of securing the proper viscosity of the composition and the film strength of the film to be finally formed, with respect to 100 parts by weight of the photopolymerizable compound, preferably 50 to 700 By weight more preferably 100 to 500 parts by weight, most preferably 150 to 450 parts by weight can be used. At this time, the kind of organic solvent that can be used is not limited in its constitution, but lower C1 to C6, acetates, ketones, cellosolves, dimethylformamide, and the like. One or more mixtures selected from the group consisting of tetrahydrofuran, propylene glycol monomethyl ether, toluene and xylene can be used.

At this time, the lower alcohols include methanol, ethane, isopropyl alcohol, butyl alcohol, isobutyl alcohol, diacetone alcohol and the like. And, the acetates are methyl acetate, ethyl acetate, Isopropyl acetate, butyl acetate, or cellosolve acetate may be used, and the ketones may be methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or acetone.

 On the other hand, the antiglare composition may further comprise at least one additive selected from the group consisting of a dispersant, a leveling agent, a wetting agent, an antifoaming agent and an antistatic agent. In this case, the additive may be added in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the photopolymerizable compound, respectively.

 The anti-glare layer may be formed by applying the above-described composition to one surface of the light-transmissive base film and proceeding with drying and photocuring. Such drying and photocuring conditions may be in accordance with general process conditions for forming an anti-glare layer. Process conditions are also described in the examples below.

 On the other hand, the optical film of the above-described embodiment further includes a low refractive layer formed on the anti-glare layer. The low refractive index layer may include a (co) polymer-containing binder number of the photopolymerizable compound and hollow silmoca particles dispersed in the binder resin.

 By including such a low refractive index layer, the reflection itself in the light transmissive base film can be reduced, and as a result, the generation and reflectance of the interference fringe in the optical film of one embodiment can be further reduced. In addition, the use of such low refractive index can reduce the diffuse reflection on the display surface of the image display device to further improve the resolution and visibility.

 The low refractive index layer may have a refractive index of 1.3 to 1.5, and may have a thickness of 1 to 300 nm, for example, to effectively suppress reflection in the base film or diffuse reflection on the display surface of the display device.

 On the other hand, the low refractive index layer may be formed from a photocurable coating composition for forming a low refractive index layer including a photopolymerizable compound and hollow silica particles. Specifically, the low refractive layer may include a binder resin including a (co) polymer of the photopolymerizable compound and hollow silica particles dispersed in the binder resin.

The photopolymerizable compound included in the low refractive layer may include a monomer or oligomer including a (meth) acrylate or a vinyl group. Specifically, the photopolymerizable compound is a (meth) acrylate or vinyl group of one or more, or two or more, Or it may include a monomer or oligomer comprising three or more.

Specific examples of the monomer or oligomer, including the (meth) acrylates, penta-erythro Li a tri (meth) ^acrylate,. Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol nucleated (meth) acrylate, tripentaerythritol hepta (meth) acrylate, trilene di Isocyanate, xylene diisocyanate, nucleated methylene diisocyanate, trimethylolpropane tri (meth) acrylate, trimethylolpropane polyethoxy tri (meth) acrylate, trimethyl propane trimethacrylate, ethylene glycol dimethacrylate ᅳ butanediol Dimethacrylate, nuxaethyl methacrylate, butyl methacrylate or mixtures of two or more thereof, or urethane modified acrylate oligomers, epoxide acrylate oligomers, etheracrylate oligomers, dendritic. Acrylate oligomers, or a combination of two or more thereof. What do you think. The molecular weight of the oligomer is preferably 1,000 to 10,000.

 Specific examples of the monomer or oligomer containing the vinyl group include divinylbenzene, styrene or paramethylstyrene.

 Meanwhile, the photocurable coating composition for forming a low refractive index layer may further include a fluorine-based compound including a functional group. Accordingly, the binder resin of the low refractive index layer may include a crosslinked polymer between the photopolymerizable compound and the fluorine-based compound including the photoreactive functional group.

 The fluorine-based compound including the photoreactive functional group may include or replace one or more photoreactive functional groups, and the photoreactive functional group may participate in the polymerization reaction by irradiation of light, for example, by irradiation of visible light or ultraviolet light. It means a functional group. The photoreactive functional group may include various functional groups known to be able to participate in the polymerization reaction by irradiation of light, and specific examples thereof include (meth) acrylate groups, epoxide groups, vinyl groups (Vinyl) or thiol groups ( Th l).

The light reflecting fluorine-based compound containing a functional group is a male may have a fluorine content of 1 wt. ⁰ /. To about 25 weight ⁰ /. If the content of fluorine is too small in the fluorine-based compound including the photoreactive functional group, the low refractive index layer may have It may be difficult to sufficiently secure physical properties such as alkali resistance. In addition, when the content of fluorine is too high in the fluorine-based compound including the photoreactive functional group, surface properties such as scratch resistance of the low refractive index layer may be reduced.

 The fluorine-based compound including the photoreactive functional group may further include silicon or a silicon compound. That is, the fluorine-based compound including the photoreactive functional group may optionally contain a silicon or silicon compound therein.

 The fluorine-based compound including the photoreactive functional group may have a weight average molecular weight (weight average molecular weight in terms of polystyrene measured by GPC method) of 2,000 to 200,000. If the weight average molecular weight of the fluorine-based compound including the photo-banung functional group is too small, the low refractive layer obtained from the photocurable coating composition of the embodiment may not have sufficient alkali resistance. In addition, if the increase average molecular weight of the fluorine-based compound including the additive photo-banung functional group is too large, the photocurability of the embodiment: the low refractive index layer obtained from the coating composition is a layered durability: may not have scratch resistance.

The photocurable coating composition is based on 100 parts by weight of the photopolymerizable compound of the monomer or oligomer comprising the (meth) acrylate or vinyl group, fluorine-based ash containing a cross-linking functional group ^. The compound may comprise 0.1 to 10 parts by weight. When the fluorine-based compound containing the photoreactive functional group in excess of the photopolymerizable compound is added, the coating property of the photocurable coating composition is lowered or the low refractive index obtained from the photocurable coating composition is more durable or scratch resistance. May not have. In addition, when the amount of the fluorine-based compound including the photoreactive functional group relative to the photopolymerizable compound is too small, the low refractive layer obtained from the photocurable coating composition may not have sufficient alkali resistance. ·

 On the other hand, the hollow silica particles means a silica particle having a maximum diameter of less than 200 nm and the empty space is present on the surface and / or inside. The hollow silica particles may have a diameter of 1 to 200 nm, or 10 to 100 nm.

As the hollow silica particles, hollow silica whose surface is coated with a fluorine compound alone, or whose surface is not coated with a fluorine compound, is used. It may be used in combination with the particles. Coating with the surface-all fluorine-based compound of the hollow silica particles may lower the surface energy, and thus the hollow silica particles may be more uniformly distributed in the photocurable coating composition, and the film obtained from the photocurable coating composition Durability and scratch resistance can be further improved.

 In addition, the hollow silica particles may be included in the composition in the form of a colloid dispersed in a predetermined dispersion medium. The colloidal phase including the hollow silica particles may include an organic solvent as a dispersion medium.

 Herein, examples of the organic solvent in the dispersion medium include alcohols such as methanol, isopropyl alcohol, ethylene glycol and butanol; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; Aromatic hydrocarbons such as toluene and xylene; Dimethylformamide. Amides such as dimethylacetamide and N-methylpyridone; Ethyl acetate, butyl acetate,. Esters such as gamma butyrolactone; Tetrahydrofuran, 1,4-dioxane and the like: ethers; Or combinations thereof.

The photo-curable coating composition when adding the photopolymerizable compound 100 parts by weight of the hollow fiber of silica particles of 10 to 500 parts by weight, or ^■ there can contain 50 to 400 parts by ^ the hollow silica particles with respect to the with ^excess' amount of binder Due to the deterioration, the scratch resistance and the wear resistance of the coating film may be lowered. In addition, when the amount of the expanded silica particles is added in a small amount, uniform film formation of the hollow silica particles may not be achieved, and a desired effect may not be properly exhibited due to a high reflectance and a refractive index.

 The photopolymerization initiator may be used without limitation as long as it is a compound known to be used in the photocurable coating composition, and specifically, a benzophenone compound, acetophenone compound, biimidazole compound, triazine compound, oxime compound, or the like. Two or more kinds thereof can be used.

 For 100 parts by weight of the photopolymerizable compound, the photopolymerization initiator may be used in an amount of 1 to 100 parts by weight.

Meanwhile, the photocurable coating composition may further include an organic solvent. Non-limiting examples of the organic solvents include ketones, alcohols, acetates and ethers, or combinations of two or more thereof. Specific examples of such an organic solvent include methyl ethyl cannon, methyl isobutyl ketone, acetyl acetone or isobutyl ^ketone, ketones, and the like; Alcohols such as methanol, ethanol, n-propane, i-propane, n-butanol, i-butanol, or t-butane; Acetates such as ethyl acetate, j-propyl acetate, or polyethylene glycol monomethyl ether acetate; Ethers such as tetrahydrofuran or propylene glycol monomethyl ether; Or two or more kinds thereof.

 The organic solvent may be included in the photocurable coating composition while being added at the time of mixing each component included in the photocurable coating composition or in the state in which each component is dispersed or mixed in the organic solvent.

 Meanwhile, the low refractive layer included in the optical film of one embodiment may be obtained by applying the above-mentioned photocurable coating composition on the antiglare layer and drying and photocuring the applied resultant. Specific process conditions of such a low refractive layer may be in accordance with conditions apparent to those skilled in the art, and are described in detail in the following examples, and thus, further description thereof will be omitted.

 Another example of the above-described optical film is a light-transmissive base film;

A binder comprising a (meth) acrylate-based crosslinked polymer, and dispersed on the binder ': A plurality of sub-micro scales ^; Antiglare layer comprising ¾ transparent particles; And

 A low refractive layer formed on the antiglare layer and including a binder resin containing a (co) polymer of a photopolymerizable compound and hollow silica particles dispersed in the binder resin; Including

The average particle size of the transparent fine particles in the D average, the translucent group a grain size of fine particles corresponding to cumulative 25 Number ⁰ /. When the particle diameter is hayeoteul listed as little starting with descending order D25, and, cumulative 75 Number _^0/0 When the particle size of the corresponding fine particles is defined as D75, the (D75-D25) / D average is 0.04 to 0.15,

 The absolute value of the refractive index difference of the light-transmitting fine particles and the binder is 0.02 to 0.25,

The total content of the transparent fine particles is 1 to 30 parts by weight _^0/0 of the total amount of the anti-glare layer,

Reflectivity is 0.5% to 2.5% It can be an optical film having a 60 ^° glossiness deviation value of 3% to 10% and a total haze of 1 to 5%.

 As described above, such an optical film can effectively suppress scattering or reflection of external light on the surface of an image display device, in particular, excellent optical properties such as low glossiness and reflectance, and an appropriate level of haze characteristics. Can be represented. Therefore, such an optical film can be very preferably used in various image display devices.

 On the other hand, according to another embodiment of the invention, there is provided an image display device including the optical film described above.

 An example of such an image display apparatus can be made as follows.

 The image display device includes a pair of polarizing plates facing each other; A thin film transistor, a color filter, and a liquid crystal cell sequentially stacked between the pair and the polarizer; And a liquid crystal display device including a backlight unit, and the optical film of the above-described embodiment may be included in the image display surface side of the liquid crystal display device.

 【Effects of the Invention】

 According to the present invention, there can be provided an optical film exhibiting low glossiness and reflectance, and excellent optical and antiglare properties such as appropriate levels of hairs properties.

 Such an optical film is preferably used in various image display devices, and can greatly improve the visibility and the like.

 [Form for implementation of invention]

 Specific embodiments of the invention are described in more detail in the following examples. However, the following examples are merely to illustrate specific embodiments of the invention, the content of the specific embodiments of the invention is not limited by the following examples.

<Preparation Example: Preparation of anti-glare layer forming composition and photocurable coating composition for forming low refractive index layer>

 (1) cleaning baths

To uniformly mix the components of Table 1 to form a composition for forming an antiglare layer Prepared. The contents of all components used in Table 1 are expressed in parts by weight.

TABLE 1

절대값

Absolute value

 (bookbinder&

 Organic particles)

 Refractive index difference

 Absolute value

 0.087 0.096 0.091 0.09 0.087 0.087 0.082 0.096 0.096 0.087 (Binder &

 Inorganic particles)

1) The total amount of the antiglare layer is calculated as the total content of the binder and the organic / inorganic fine particles, except for the dispersant, the solvent, and the initiator, which are removed during the formation of the antiglare layer forming composition.

 2) The refractive index of the binder is crosslinked according to the composition and the production example described later.

It was measured after (co) polymerization, and the refractive index of the organic / inorganic fine particles was derived as an average value when two or more were used.

1) UA-306T: (Kyoeisha): 6-functional acrylic ray ¾-type compound formed by reacting two triacrylates of pentaerythri with toluene diisocyanate

 2) 8BR-500 (TAISB FINE CHEMICAL):

 A polymer in which a polyacryl main chain is bound to around 40 functional urethane acrylate functional groups.

 3) TMPTA: trimethylolpropane triacrylate

 4) PETA: Pentaerythritbl triacrylate

 5) I184 (lrgacure 184):: photoinitiator, the product made by Ciba.

 6) BYK 300: PDMS dispersant

 7) 1 13BQ (XX-113BQ, manufactured by Sekisui Plastic): PMMA-PS crosslinked copolymer fine particles having a refractive index of 1.555 and an average particle diameter of 2

 97BQ (XX-97, manufactured by Sekisui Plastic): PMMA-PS crosslinked copolymer fine particles having an index of refraction of 1.525 (about 1.53) and an average particle diameter of 2.

9) 9600A: Spherical silica fine particles having a volume average particle diameter of 100 nm and a refractive index of 1.43 (X24-9600A; manufactured by Shinetsu) 10) MA-ST: A dispersion solution in which methan is dispersed in methan at a concentration of 30% of spherical silica fine particles (product of Nissan Chemical) having a volume average particle diameter of 12 nm and a refractive index of 1.43.

(2) Preparation of Photocurable Coating Composition for Forming Low Refractive Layer

 After mixing the remaining components of Table 2, MIBK (methyl isobutyl ketone) and

It diluted with the mixed solution (weight ratio = 1: 1) of IPA, and prepared the photocurable coating composition for low refractive layer formation. The content of all components used in Table 2 is expressed in parts by weight.

 TABLE 2

1) DPHA: Dipentaerythritol hexaacrylate, molecular weight 524.51 g / mol, manufactured by Kyoeisha.

 2) THRULYA 4320: hollow silica dispersion, 20 wt% solids in MIBK solvent, catalyzed.

 3) lrgacure-127: photoinitiator, manufactured by BASF Corporation.

4) RS-907: Fluorine-based compound containing photoreactive functional group, 30 wt% of solids in MIBK solvent, manufactured by DIC Corporation. <Examples 1 to 4 and Comparative Examples 1 to 6: Preparation of Optical Films> As shown in Table 3 below, in PET substrate films having a thickness of 100 / and a refractive index of 1.6 to 1.7, the Preparation Examples 1 to 4 or a comparison The antiglare layer compositions prepared in Preparation Examples 1 to 5 were applied and dried at 90 ^° C. for 1 minute, thereby irradiating 150 mJ / citf of ultraviolet rays to prepare an antiglare layer.

 And in Examples 1 to 4 and Comparative Examples 1 to 6, the low refractive index on the antiglare layer was formed as follows.

The composition prepared in Preparation Example 5 was applied onto the antiglare layer by Meyer Bar # 3, and dried at 90 ^° C. for 1 minute. In addition, an optical film was formed by irradiating 180 mJ / crf of ultraviolet rays to the dried material under nitrogen purge to form a low refractive index having a thickness of 100 nm.

Experimental Example: Measurement of Physical Properties of Optical Film

 The physical properties of the prepared optical film were measured according to the following method, which is shown together in Table 3 below.

1. Measurement of particle size distribution of translucent (organic / inorganic) particles

 The particle diameters of the light-transmitting fine particles of organic / inorganic fine particles contained in Production Examples 1 to 4 and Comparative Production Examples 1 to 5 were measured by COULTER PARTICLE SIZE ANALYZER, and they were arranged in the order of smallest to largest size. Derived. At this time, the organic fine particles were mixed with a solvent such as ethanol, methanol and isopropyl alcoh to prepare a dispersion solution. In the case of the inorganic fine particles supplied in the dispersion state, it was analyzed by diluting with the same solvent as the dispersion solvent.

 From the particle size distribution curve, the total average particle diameter of the light-transmitting fine particles

To obtain a D average, a particle diameter of fine particles to the transparent group that the particle diameter of the particles corresponding to cumulative 25 Number ⁰ /. When the fine particles hayeoteul particle size is listed in descending order starting with small to D25, and, cumulative 75 Number _^0/0 Each was calculated | required by D75. From these measured values, the value of (D75-D25) / D average was computed. 2. Refractive Index Measurement

Refractive index of the binder, anti-glare layer, low refractive index layer, etc. included in the optical film was measured by using an ellipsometer coated on the wafer. More specifically, the refractive index of the binder, the anti-glare layer and the low refractive index layer is applied to a 3cm X 3cm wafer each composition, after the coating by using a spin coater (coating conditions: 1500rpm, 30 seconds), 90 ^° C It was dried for 2 minutes at and irradiated with ultraviolet light under the condition of 180 mJ / cm ² under nitrogen purging. This formed each coating worm having a thickness of 100nm.

For this coating layer, using a refractive index measurement gong-ratio (model name: M-2000) of A. Woollam Co., an incident angle of 70 ^° was applied, and linearly polarized light was measured in a wavelength range of 380 nm to 1000 nm. Wherein the measured line polarized measurement data (ellipsometry data (Ψ, Δ) ) was optimized (fitting) for using the software Complete EASE the MSE by the general formula [1 Kosh model _(Cauchy. Model) of is less than or equal to 3. '

 fiiTC ^^ 4- ™ r- * f wherein η (λ) is the refractive index at λ wavelength (300nm ~ 1800nm), A, B,

C, is a Kosh parameter.

 In addition, the refractive index of the base film and each fine particle used the information provided about a commercial item. 3. Overall / Internal / External Haze Rating

 An optical film specimen of 4 cm × 4 cm was prepared and measured three times with a haze meter (HM-150, A light source, Murakamisa) to calculate an average value, which was calculated as the total haze value. In the measurement, the transmittance was measured according to JIS K 7361 standard and the haze according to JIS K 7105 standard. In the internal haze measurement, an adhesive film having a total haze of 0 was applied to the coating surface of the optical film to be measured to make the surface irregularities flat, and then the internal haze was measured in the same manner as the above whole haze.

External haze was computed as the average value of the value which computed the difference of the measured value of total haze and internal haze. 4. 20 ^° / 60 ° glossiness and its deviation value evaluation

The glossiness of 20 ^° / 60 ^° was measured using micro-TRI-gloss manufactured by BYK Gardner. When measuring, attach black tape (3M) to prevent light from passing through the surface where the nose layer of the base film is not formed.

Was 20 ^° / 60 ^° measuring the gloss at different to 5 20 ^° / 60 ^°, the average value was calculated by measuring at least 5 times in each glossiness value.

The deviation value of 60 ^° glossiness was calculated by measuring the glossiness 10 times by the above method, and then calculating the deviation from the data. 05. Reflectance

 The reflectance was measured as the average reflectance of S by SHIMADZU Corporation using idSpec 3700.

 Specifically, attach a black tape (Vinyl tape 472 Black, manufactured by 3M) to prevent light from being transmitted to the surface where the coating layer is not formed in the optical peeling — sampling 5 interval 1 mm, time constant 0.1 sec, slit width 20 nm, After fixing the measurement conditions at medium scanning speed, the optical film was measured by irradiating light of the wavelength of 380nm to 780nm by applying the 100T mode.

TABLE 3

Referring to Table 3, it was confirmed that the optical film of the example can exhibit excellent optical properties such as low glossiness and reflectance, and an appropriate level of haze properties. On the other hand, Comparative Examples 1 and 4 of the optical properties high glossiness over the deviation value ^": ¾ was confirmed that the uniformity greatly reduced. In addition, in Comparative Example 5, it was confirmed that the glossiness was too high and the reflectance was high, so that reflection of external light could not be suppressed properly.

 In Comparative Examples 2 and 3, since the haze value was too low and the external reflection image was not scattered and visually recognized, it was confirmed that the visibility and image sharpness of the screen were poor. On the contrary, in Comparative Example 6, the internal haze and the total haze value were too high, the optical properties were insufficient, and the visibility of the screen was poor.

Claims

[Claim]  [Claim 1]  Light-transmissive base film;  An antiglare layer comprising a binder containing a (meth) acrylate-based crosslinked polymer, a micron (/ ni) scale organic fine particle dispersed on the binder, and a nano (nm) scale inorganic fine particle dispersed on the binder. ; And  A low refractive layer formed on the antiglare layer and including a binder resin containing a (co) polymer of a photopolymerizable compound and hollow silica particles dispersed in the binder resin; Including, The average particle diameter of the organic and inorganic fine particles is D average, and when the organic and inorganic fine particles are arranged in descending order from the smallest particle size, the particle diameter of the fine particles corresponding to the cumulative number of 25 ⁰ / _. (D75-D25) / D average is 0.25 or less, when the particle size of 75 square% is defined as D75 '.  The absolute value of the refractive index difference between the organic and inorganic fine particles and the binder is 0.01 to 0.25, The total content of the organic and inorganic fine particles is 1 to 30 weight ⁰ /. Of the total content of the antiglare 专, − An optical film having a 60 ^° glossiness deviation value of 3% to 10% and a total haze of 1 to 5%. [Claim 2]  According to claim 1, wherein the light-transmitting base film is a cellulose ester base film, a polyester base film, a poly (meth) acrylate base film or a polycarbonate base film having a thickness of 20 to 500 film. [Claim 3] The polymer according to claim 1, wherein the (meth) acrylate-based crosslinked polymer is a polyurethane-based polymer having a (meth) acrylate compound having a 3-6 functional monomolecular form and a (meth) acrylate functional group having 10 or more functional groups, Poly (meth) acrylic An optical film comprising a crosslinked (co) polymer of a polyfunctional (meth) acrylate-based compound including a polymer or a polyester-based polymer. [Claim 4]  The optical film of claim 1, wherein the binder has a refractive index of about 1.50 to about 1.60. [Claim 5]  The optical film of claim 1, wherein the organic fine particles are resin fine particles comprising a polystyrene resin, a poly (meth) acrylate resin, or a poly (meth) acrylate-co-styrene copolymer resin. [Claim 6]  The optical film of claim 1, wherein the organic fine particles are spherical particles having a particle diameter of 1 to 5, and have a refractive index of 1.5 to 1.57. [Claim 7]  The optical film of claim 1, wherein the inorganic fine particles are metal oxide fine particles including silica, alumina, zirconia, or titania. [Claim 8]  The optical film of claim 1, wherein the inorganic fine particles are spherical particles having a particle diameter of 10 nm to 300 nm, and have a refractive index of 1.4 to 1.75. [Claim 9]  The method of claim 1, wherein the D average is 1.7 μηι to 2.3 / aii, D25 is from 1.5 ni to 2.1, D75 is 1. An optical film of 9 βη \ to 2.5 / an. [Claim 10] According to claim 1, wherein the antiglare is an optical fiber having a thickness of 1 to 10 卿 i afl porn  ㅁ · [Claim 1 11]  The optical film of claim 1, wherein the low refractive layer has a refractive index of 1.3 to 1.5 and a thickness of 1 to 300 nm. [Claim 12]  Light-transmissive base film;  An antiglare layer comprising a binder including a (meth) acrylate-based crosslinked polymer and a plurality of light-transmitting fine particles of a sub-micron scale dispersed on the binder; And  A low refractive index comprising a binder resin formed on the antiglare layer and containing a (co) polymer of a photopolymerizable compound and dispersed silica particles dispersed in an additive binder resin; Including, The average particle size of the transparent fine particles in the D average, the translucent group a grain size of fine particles corresponding to cumulative 25 Number ⁰ /. When the particle diameter is hayeoteul listed as little starting with descending order D25, and, cumulative 75 Number _^0/0 When the particle size of the corresponding fine particles is defined as D75, the (D75-D25) / D average is 0.04 to 0.15,  The absolute value of the refractive index difference between the light-transmitting fine particles and the binder is 0.02 to 0.25, The total content of the transparent fine particles is 1 to 30 parts by weight _^0/0 of the total amount of the anti-glare layer,  Reflectivity is 0.5% to 2.5%, An optical film having a 60 ^° glossiness deviation value of 3% to 10% and a total haze of 1 to 5%. [Claim 13]  An image display device comprising the optical film of claim 1