KR102414309B1 - Optical film, polarizing plate comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

base layer; And as an optical film comprising a first resin layer, a second resin layer and a third resin layer sequentially formed on the upper surface of the base layer, one or more embossed at the interface between the first resin layer and the second resin layer of optical patterns; and a flat portion formed between the embossed optical pattern and the embossed optical pattern immediately adjacent thereto, the first resin layer has a lower refractive index than the second resin layer, and the second resin layer is a UV curable compound, An optical film, which is formed of a composition for a second resin layer including a photoinitiator and a thermal initiator, a polarizing plate including the same, and an optical display device including the same are provided.

Description

Optical film, polarizing plate including same, and optical display device including same

The present invention relates to an optical film, a polarizing plate, and an optical display device including the same.

The antireflection film improves the screen quality of the optical display device by lowering the minimum reflectance for external light. Conventional anti-reflection film has a structure in which a high refractive index layer and a low refractive index layer are sequentially stacked on a base layer, or a hard coating layer, a high refractive index layer, and a low refractive index layer are sequentially stacked on a base layer. However, since the anti-reflection film has to be disposed on the outside of the optical display device in order to realize the effect, it must have excellent hardness.

On the other hand, in order to increase visibility in the optical display device, a patterned film may be used. In the case of such a film, if a pattern layer exists and a resin layer is coated on the pattern layer, the pattern must be planarized, and the coating thickness for planarization increases due to the curved portions of the pattern. Therefore, the thicker the coating layer made of the cured resin, the more vulnerable it is to bending, so it is not easy to satisfy both bending and hardness at the same time.

Background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2015-084029 and the like.

An object of the present invention is to provide an optical film capable of simultaneously increasing hardness and flexibility.

Another object of the present invention is to provide an optical film having an optical pattern and capable of simultaneously increasing hardness and flexibility.

One aspect of the present invention is an optical film.

1. The optical film is a base layer; And as an optical film comprising a first resin layer, a second resin layer and a third resin layer sequentially formed on the upper surface of the base layer, one or more embossed at the interface between the first resin layer and the second resin layer of optical patterns; and a flat portion formed between the embossed optical pattern and the embossed optical pattern immediately adjacent thereto, the first resin layer has a lower refractive index than the second resin layer, and the second resin layer is a UV curable compound, It is formed of a composition for a second resin layer including a photoinitiator and a thermal initiator.

In 2.1., the photoinitiator is included in an amount of 0.1 wt% to 5 wt% of the second resin layer.

In 3.1-2, the thermal initiator is included in an amount of 0.1 wt% to 3 wt% of the second resin layer.

In 4.1-3, the photoinitiator includes at least one of phosphorus-based and diketone-based.

In 5.1-4, the thermal initiator includes at least one of azo-based and organic peroxide-based.

In 6.1-5, the UV curable compound includes at least one of a urethane (meth)acrylic compound and an aromatic (meth)acrylic compound.

In 7.1-6, the second resin layer further includes high refractive index particles having a higher refractive index than that of the first resin layer.

In 8.7, the high refractive index particles include at least one of zirconia and titania.

In 9.7, the high refractive index particles are included in an amount of 20 wt% to 75 wt% of the second resin layer.

In 10.1-9, the embossed optical pattern is a trapezoidal, rectangular or square optical pattern in cross section.

In 11.1-10, the embossed optical pattern is formed in a stripe-like elongated form in the longitudinal direction of the embossed optical pattern.

In 12.1-11, the refractive index difference between the second resin layer and the first resin layer is 0.1 or more.

In 13.1-12, the refractive index of the third resin layer is lower than that of the first resin layer and the second resin layer, respectively.

In 14.1-13, the third resin layer is formed of a composition for the third resin layer including inorganic particles, a fluorine-containing monomer or oligomer thereof, a fluorine-free monomer or oligomer thereof, an initiator, and a fluorine-containing additive.

In 15.14, the inorganic particles comprise hollow silica.

In 16.14, the inorganic particles are included in an amount of 20 wt% to 70 wt% based on the solid content of the composition for the third resin layer.

In 17.1-16, the composition for the second resin layer or the second resin layer does not include a thermosetting compound.

In 18.1-17, the optical film has a pencil hardness of 2H or more, and the optical film has a radius of curvature of 5 mm or less when the flexibility is evaluated in both the longitudinal and width directions of the embossed optical pattern.

The polarizing plate of the present invention is a polarizer; and an optical film of the present invention formed on one surface of the polarizer.

The optical display device of the present invention includes the optical film of the present invention.

The present invention provides an optical film capable of simultaneously increasing hardness and flexibility.

The present invention provides an optical film having an optical pattern and capable of simultaneously increasing hardness and flexibility.

1 is a cross-sectional view of an optical film according to an embodiment of the present invention.

With reference to the accompanying drawings, it will be described in detail so that those skilled in the art can easily implement the present invention by way of example. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. The length and size of each component in the drawings are for explaining the present invention, and the present invention is not limited to the length and size of each component described in the drawings.

In this specification, "upper" and "lower" are defined based on the drawings, and depending on the perspective of the city, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include cases where other structures are interposed in the middle as well as immediately above. On the other hand, reference to “directly on”, “directly on” or “directly formed” or “directly formed directly on” means without intervening other structures.

As used herein, "top part" means the highest part of the embossed optical pattern.

As used herein, "aspect ratio" means a ratio of the maximum height to the maximum width of the embossed optical pattern (maximum height/maximum width).

As used herein, the term “period” refers to a distance between adjacent embossed optical patterns, for example, the sum of the maximum width of one embossed optical pattern and the width of a flat portion immediately adjacent to the embossed optical pattern.

In the present specification, "plane direction retardation (Re)" is expressed by the following formula A:

[Formula A]

Re = (nx - ny) x d

(In Formula A, nx and ny are the refractive indices of the slow axis direction and the fast axis direction of the substrate layer, respectively, at a wavelength of 550 nm, and d is the thickness of the substrate layer (unit: nm)).

As used herein, “(meth)acryl” means acrylic and/or methacrylic.

The inventor of the present invention is an optical film in which a first resin layer, a second resin layer and a third resin layer are sequentially formed on a base layer, and the first resin layer has a lower refractive index than the second resin layer. The base layer is formed with a pattern portion having an embossed optical pattern described in detail below at the interface with the second resin layer, and the second resin layer is a composition for a second resin layer comprising a UV curable compound, a photoinitiator and a thermal initiator. By being formed, the hardness and flexibility of the optical film can be remarkably improved compared to the case where the photoinitiator alone or the thermal initiator alone is included, and it was confirmed that there is an effect of improving the refractive index of the second resin layer and completed the present invention. In particular, it was confirmed that the optical film of the present invention had excellent flexibility when the embossed optical pattern was formed in a stripe-like extended form and the flexibility was evaluated in both the longitudinal and width directions of the embossed optical pattern. did

In one embodiment, the optical film may have a pencil hardness of 2H or more, for example, 2H to 6H. In the above range, even if it is used as the outermost film in the display device, there may be an effect of sufficiently protecting the optical element in the display device. The "pencil hardness" can be measured by the evaluation method detailed below.

In one embodiment, the optical film may have a thickness of 40 μm to 300 μm, for example, 50 μm to 250 μm. Within the above range, it can be used for an optical display device.

In one embodiment, the optical film may have a radius of curvature of 5 mm or less, for example, 0 mm to 5 mm when the flexibility is evaluated in both the longitudinal and width directions of the embossed optical pattern. Within the above range, it may be used as an optical film in a foldable display device. The "flexibility" can be measured by the evaluation method detailed below.

In one embodiment, the optical film may have a total light transmittance of 80% or more in the visible light region, for example, 85% to 100%. Within the above range, it can be used for an optical display device.

In one embodiment, the optical film may have a minimum reflectance of 2% or less, such as 0% or more and 1.5% or less. In the above range, it is possible to produce an anti-reflection effect.

Hereinafter, an optical film according to an embodiment of the present invention will be described with reference to FIG. 1 .

Referring to FIG. 1 , the optical film may include a base layer 300 , a first resin layer 100 , a second resin layer 200 , and a third resin layer 400 . A first resin layer 100 , a second resin layer 200 , and a third resin layer 400 are sequentially formed on the upper surface of the base layer 300 .

base layer

The base layer 300 is formed on the lower surface of the first resin layer 100 (the light incident surface of the first resin layer), and can support the first resin layer 100 and the second resin layer 200 . . The light passing through the base layer 300 may be incident on the first resin layer 100 and may be emitted.

The base layer 300 may be formed directly with the first resin layer 100 to reduce the thickness of the optical film. The "directly formed" means that any adhesive layer, adhesive layer, or adhesive layer is not interposed between the base layer 300 and the first resin layer 100 .

The base layer 300 may have a total light transmittance of 90% or more in the visible light region, for example, 90% to 100%. In the above range, light can be transmitted without affecting the incident light.

The base layer 300 may be a protective film or a protective coating layer including a light incident surface and a light output surface opposite to the light incident surface. Preferably, by using a protective film as the base layer, the degree of support for the first resin layer and the second resin layer may be excellent.

When the base layer is a protective film, the base layer may include a single optically transparent resin film. However, the base layer may include a case in which a plurality of resin films are laminated. The protective film may be formed by melting and extruding a resin. If necessary, a further stretching step may be added. The resin is a cellulose ester-based resin including triacetyl cellulose, a cyclic polyolefin-based resin including an amorphous cyclic polyolefin, a polycarbonate-based resin, a polyester-based resin including polyethylene terephthalate (PET), and the like, poly Polyacrylate-based resins, polyvinyl alcohol-based resins, poly It may include at least one of a vinyl chloride-based resin and a polyvinylidene chloride-based resin.

The protective film may be an unstretched film, but may be a retardation film or an isotropic optical film having a retardation within a predetermined range by stretching the resin by a predetermined method. In one embodiment, the protective film may be an isotropic optical film having Re of 0 nm or more and 60 nm or less, specifically 40 nm to 60 nm. The image quality may be improved by compensating the viewing angle within the above range. The "isotropic optical film" means a film in which nx, ny, and nz are substantially the same, and the "substantially identical" includes both cases including the exact same as well as a slight error. In another embodiment, the protective film may be a retardation film having Re of 60 nm or more. For example, the protective film may have Re of 60 nm to 500 nm, and 60 nm to 300 nm. For example, the protective film may have Re of 3,000 nm or more, specifically 5,000 nm or more, more specifically 6,000 nm or more, and more specifically 6,000 nm to 10,000 nm. Within the above range, it is possible to prevent rainbow spots from being visually recognized.

The protective coating layer may be formed of a composition including an active energy ray-curable compound and a polymerization initiator. The active energy ray-curable compound may include at least one of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone-based resin. The cationically polymerizable curable compound may be an epoxy compound having at least one epoxy group in the molecule, or an oxetane compound having at least one oxetane ring in the molecule. The radically polymerizable curable compound may include at least one of a (meth)acrylate monomer and a (meth)acrylate oligomer having at least one (meth)acryloyloxy group in the molecule.

The thickness of the base layer 300 may be 5 μm to 200 μm, specifically, 30 μm to 120 μm. Within the above range, it can be used for optical films.

The refractive index of the base layer 300 may be 1.3 to 1.8, preferably 1.4 to 1.7. In the above range, it is possible to obtain an anti-reflection effect when used as an outermost film in a display device through a relationship of a refractive index with the first resin layer.

On at least one surface (at least one of the upper surface and the lower surface) of the base layer 300, a surface treatment layer such as a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflection layer, an ultra-low reflection layer is further formed it might be The hard coating layer, the anti-fingerprint layer, the anti-reflection layer, etc. may provide additional functions to the protective layer, the polarizing film, and the like. The primer layer can improve adhesion between the base layer and the adherend.

1st resin layer

The first resin layer 100 is formed on the upper surface of the base layer 300 (eg, the light emitting surface of the base layer), and the light emitted from the base layer may be emitted through the first resin layer.

The first resin layer 300 has a lower refractive index than the second resin layer 200 . Through this, the optical film may produce an antireflection effect through the refractive index relationship between the second resin layer and the first resin layer. The difference in refractive index between the second resin layer 200 and the first resin layer 100 may be 0.1 or more, for example, 0.1 to 0.2. In the above range, the optical film may have an antireflection effect. The first resin layer 100 may have a refractive index of 1.6 or less, for example, 1.40 to 1.55. In the above range, it may be easy to realize the antireflection effect of the optical film by securing a difference in refractive index with the second resin layer.

The first resin layer 200 may be formed of a composition for a first resin layer including a UV curable resin capable of providing the refractive index range. The composition for the first resin layer may further include at least one of a photoinitiator, an additive, and a solvent described in the second resin layer below.

The first resin layer 100 is formed in direct contact with the second resin layer 200 , and the first resin layer 100 has a pattern portion formed at the interface with the second resin layer 200 . The upper surface of the first resin layer 100 is an interface between the first resin layer 100 and the second resin layer 200 and may correspond to the pattern portion.

The pattern unit includes one or more embossed optical patterns 110; and a flat portion 120 formed between the embossed optical pattern 110 and the optical pattern 110 immediately adjacent thereto. In the pattern portion, a combination of the embossed optical pattern 110 and the flat portion 120 is repeatedly formed. The embossed optical pattern 110 has a relatively large aspect ratio compared to the known irregularities, and the embossed optical pattern 110 and the flat portion 120 are regularly arranged. Through this, the pattern unit may help to improve visibility by spreading the emitted light of the optical display device. The "embossed optical pattern" means an optical pattern in which the optical pattern protrudes from the first resin layer toward the second resin layer.

The pattern part satisfies Equation 1 below, and the embossed optical pattern 110 may have a base angle θ of 75° to 90°. The base angle θ means an angle between 75° and 90° between the slope 112 of the embossed optical pattern 110 and the line of the maximum width W of the embossed optical pattern 110 . In this case, the inclined surface 112 means an inclined surface directly connected to the flat portion 120 of the embossed optical pattern 110 . Within the above range, the visibility of the optical display device can be improved. Specifically, the base angle θ may be 80° to 90°, and P/W (ratio of P to W) may be 1.2 to 8:

[Equation 1]

1 < P/W ≤ 10

(In Equation 1, P is the period of the pattern part (unit: μm),

W is the maximum width of the embossed optical pattern (unit: μm).

The embossed optical pattern 110 may be an optical pattern including one or more inclined surfaces 112 having a first surface 111 formed on the top and connected to the first surface 111 . 1 shows a trapezoidal optical pattern in which two adjacent inclined surfaces 112 are connected by a first surface 111 of the embossed optical pattern 110, but the present invention is not limited thereto, and the embossed optical pattern In addition to the optical pattern having a trapezoidal cross section, it may be a rectangular or square optical pattern.

The first surface 111 is formed on the top, and the light reaching the second resin layer 120 is further diffused by the first surface 111 , thereby increasing the luminance. The first surface 111 may be a flat surface to facilitate the manufacturing process of the optical film. However, the first surface 111 may be formed with fine irregularities or may have a curved surface. When the first surface is formed as a curved surface, a lenticular lens pattern may be formed. 1 shows a pattern in which one plane is formed on the top (the first surface) and the inclined plane is flat, and the cross-section is trapezoidal (eg, the upper part of a prism having a triangular cross-section is cut, cut-prism shape). . However, the embossed pattern has a first surface formed on the top and an embossed pattern with a curved surface (eg, a contrast improvement layer that is a cut-lenticular lens in which the upper part of the lenticular lens pattern is cut, or the upper part of the microlens pattern is cut shape of a cut-micro lens) may also be included in the scope of the present invention. In addition, a pattern having an N-shaped cross-section such as a rectangle or a square (N is an integer of 3 to 20) may also be included. The first surface 111 may have a width A of 0.5 μm to 30 μm, specifically 1 μm to 15 μm. Within the above range, it can be used for an optical display device.

The embossed optical pattern 110 may have an aspect ratio (H/W) of 0.1 to 10, specifically 0.1 to 7, more specifically 0.1 to 5, and even more specifically 0.1 to 2. Within the above range, an optical effect may be improved when applied to an optical display device.

The maximum height (H) of the embossed optical pattern 110 may be greater than 0 µm and less than or equal to 30 µm, specifically greater than or equal to 0 µm and less than or equal to 20 µm, and more specifically greater than or equal to 0 µm to less than or equal to 15 µm. The maximum width W of the embossed optical pattern 110 may be greater than 0 µm and less than or equal to 20 µm, specifically greater than 0 µm and less than or equal to 15 µm, and more specifically greater than or equal to 0 µm and less than or equal to 10 µm. In the above range, moiré and the like may not appear.

The ratio (W/L) of the maximum width (W) of the optical pattern 110 to the width (L) of the flat portion 120 is greater than 0 and less than or equal to 9, specifically 0.1 to 3, more specifically 0.1 to 2 days can In the above range, there may be an effect of preventing moiré. The width L of the flat portion 210 may be 1 μm to 50 μm, specifically, 1 μm to 20 μm. In the above range, there may be an effect of increasing the front luminance.

The period P may be 1 μm to 50 μm, specifically 1 μm to 40 μm. Moiré can be prevented within the above range.

1 shows a pattern portion in which the optical patterns of adjacent embossed optical patterns are formed with the same base angle, first surface width, maximum height, maximum width, period, and flat portion, respectively. However, an optical film in which adjacent optical patterns have different base angles, first surface widths, maximum heights, maximum widths, periods, and flat portions may also be included in the scope of the present invention.

Although not specified in FIG. 1 , FIG. 1 shows that the optical pattern is formed in a stripe-shaped elongated form in the longitudinal direction of the optical pattern, but the optical pattern may be formed in a dot form. The "dot" means that the optical patterns are dispersed spaced apart from each other. Preferably, the optical pattern may be formed in an extended form in a stripe shape. The optical film of the present invention may have excellent flexibility even when the optical film is bent in each of the width and length directions of the optical pattern when the optical pattern is formed in a stripe shape.

FIG. 1 shows that the pattern part completely contacts the second resin layer 200 . However, contact of the pattern portion with at least a portion of the second resin layer 200 may also be included in the scope of the present invention. A portion not in contact between the second resin layer 200 and the first resin layer 100 may be filled with air or a resin having a predetermined refractive index.

2nd resin layer

The second resin layer 200 is formed on the upper surface of the first resin layer 100 , and light emitted from the first resin layer 100 may be emitted through the second resin layer.

The upper surface of the first resin layer 100 is composed of an embossed optical pattern 110 and a flat portion 120 . The second resin layer 200 may planarize the surface of the optical film while filling the space (gap) between the embossed optical patterns 110 . The upper surface of the second resin layer 200 , that is, the light exit surface of the second resin layer 200 may be a flat surface.

The maximum thickness of the second resin layer 200 may be greater than 0 µm and less than or equal to 30 µm, for example, greater than or equal to 0 µm to less than or equal to 20 µm. In the above range, it is possible to prevent the occurrence of warpage such as curl.

The maximum thickness of the second resin layer 200 - the maximum height (also referred to as 'flesh thickness') of the optical pattern 110 is greater than 0 µm and less than or equal to 30 µm, for example, greater than 0 µm and less than or equal to 20 µm, greater than 0 µm and less than or equal to 15 µm can be the following Within the above range, there may be an effect of improving flexibility and hardness.

The second resin layer 200 may have a refractive index of 1.5 or more, for example, 1.55 to 1.65. In the above range, it is possible to increase the antireflection effect through the refractive index relationship with the first resin layer.

The second resin layer 200 may be formed of a composition for a second resin layer including a UV curable compound, a photoinitiator, and a thermal initiator.

When the second resin layer is formed of a composition for a second resin layer that contains only a photoinitiator and does not contain a thermal initiator, the effect of improving the flexibility is weak and the effect of increasing the refractive index of the second resin layer is weak. When the second resin layer is formed of a composition for a second resin layer that contains only a thermal initiator and does not include a photoinitiator, the effect of improving hardness is weak and the effect of increasing the refractive index of the second resin layer is weak.

In the optical film in which the pattern part described above is formed by forming the second resin layer with a composition for a second resin layer containing a photoinitiator and a thermal initiator at the same time, the present invention improves the hardness of the optical film, improves flexibility, and improves the refractive index at the same time can be obtained

After coating the composition for the second resin layer on the first resin layer, the second resin layer is passed through a drying zone under a certain condition so that the solvent contained in the composition for the second resin layer is volatilized and passes through the UV zone again. It can be formed by completely curing the compound. As the curing initiation reaction by the thermal initiator proceeds in the process of passing through the drying zone, curing of the UV curable compound starts, and both the thermal initiator and the photoinitiator in the UV zone undergo a curing initiation reaction to increase the degree of curing of the UV curable compound. The hardness of a resin layer and an optical film can be raised. In addition, as the UV curable compound is gradually cured while sequentially passing through the drying zone and the UV zone, the molecular weight of the polymer constituting the UV cured product increases, thereby improving flexibility at the same time.

The UV curable compound may include at least one of a UV curable resin, a UV curable oligomer, and a UV curable monomer. For example, the UV curable compound is an aromatic (meth)acrylic compound including a urethane (meth)acrylic compound, a bisphenol (meth)acrylic compound, etc., a polyester (meth)acrylic compound, a polyether (meth)acrylic compound, a fluoride ( Meth)acrylic compound, unsaturated (meth)acrylic compound, epoxy (meth)acrylic compound, allylphatic (meth)acrylic compound, fluorene (meth)acrylic compound, biphenyl (meth)acrylic compound, thiophenyl (meth)acrylic compound , a thiobenzyl (meth)acrylic compound, a phenylsulfide (meth)acrylic compound, and one of thionaphthalene (meth)acrylic compounds may be included. Preferably, as the UV curable compound, at least one of a urethane (meth)acrylic compound and an aromatic (meth)acrylic compound may be used. In this case, the effect of improving flexibility and hardness of the present invention can be significantly improved.

The UV curable compound may be included in an amount of 20 wt% to 75 wt%, preferably 25 wt% to 65 wt%, 30 wt% to 70 wt% based on the solid content of the composition for the second resin layer. Within the above range, it is possible to improve the hardness and improve the flexibility of the optical film.

The photoinitiator may include a photoinitiator capable of curing the UV curable compound by a photoinitiated reaction. The photoinitiator may include a photoradical initiator. For example, the photoinitiator is phosphorus-based, diketone-based, acetophenone-based, benzophenone-based, Michler benzoylbenzoate-based, thioxanthone-based, popiophenone-based, benzyl-based, acylphosphine oxide-based, preferably cyclo A phosphorus-based photoinitiator including a diketone type including a hexylphenyl ketone type or a bisphosphine oxide type may be used, but is not limited thereto.

The photoinitiator may be included in an amount of 0.1 wt% to 5 wt%, preferably 0.3 wt% to 3 wt%, based on the solid content of the composition for the second resin layer. In the above range, the UV-curable compound can be sufficiently cured, and a residual amount of the photoinitiator remains to solve the problem of increasing the haze of the optical film, and there can be an effect of improving the flexibility and improving the hardness of the optical film.

The thermal initiator may aid UV curing of the UV curable compound by a thermal initiation reaction or may cure a portion of the UV curable compound. For example, the thermal initiator is azo, organic peroxide, quinine, nitro, halogenated acyl, hydrazone, mercapto, imidazole, benzoin, diketone, phenone, aromatic amine, preferably It may contain an azo-based or organic peroxide-based thermal initiator.

The thermal initiator may be included in an amount of 0.1 wt% to 3 wt%, preferably 0.3 wt% to 2 wt%, based on the solid content in the composition for the second resin layer. In the above range, a portion of the UV-curable compound may be cured, and a residual amount of the thermal initiator may be left to solve the problem that the haze of the optical film rises, and there may be an effect of improving the flexibility and hardness of the optical film.

The total amount of the photoinitiator and the thermal initiator may be included in an amount of 0.1 wt% to 10 wt%, preferably 0.3 wt% to 5 wt%, based on the solid content of the composition for the second resin layer. Within the above range, it is possible to increase the flexibility, increase the hardness, and increase the refractive index.

In one embodiment, the photoinitiator: thermal initiator may be included in a weight ratio of 1:0.1 to 1:5, preferably 1:0.5 to 1:3. Within the above range, it may be easy to implement the effects of the present invention.

The composition for the second resin layer may include a common solvent such as ethanol, propylene glycol monomethyl ether acetate, methyl ethyl ketone, methyl isobutyl ketone, etc. for the applicability of the composition for the second resin layer, but is limited thereto doesn't happen The composition for the second resin layer may further include conventional additives known to those skilled in the art. The additive may include at least one of a dispersing agent, a leveling agent, a surface control agent, an antioxidant, an antifoaming agent, an ultraviolet absorber, and a light stabilizer.

The composition for the second resin layer may further include particles having a high refractive index in order to increase the refractive index of the composition for the second resin layer. The high refractive index particles further increase the refractive index of the second resin layer, thereby increasing the difference in refractive index between the first resin layer and the second resin layer, thereby further enhancing the antireflection effect.

The particles of high refractive index are particles having a high refractive index compared to the first resin layer, and may have a refractive index of 1.5 or more, for example, 1.55 to 2.5, 1.60 to 2.2. Within the above range, an effect of increasing the refractive index of the second resin layer can be expected. The high refractive index particles may include conventional inorganic particles, organic particles, organic-inorganic particles, or mixtures thereof, as long as they can provide the refractive index range described above. For example, the inorganic particles may include one or more of zirconia (zirconium oxide), titania (titanium oxide), alumina, silica, antimony oxide, zinc oxide, magnesium oxide, tin oxide, and indium oxide. Preferably, the inorganic particles may include at least one of zirconia and titania.

The particles of high refractive index may have an average particle diameter (D50) of 1 nm to 50 nm, for example, 5 nm to 30 nm. Within the above range, it may be included in the second resin layer, and may have an effect of increasing the refractive index. The particles having a high refractive index may be included in an amount of 20 wt% to 75 wt%, for example, 35 wt% to 65 wt% of the second resin layer. In the above range, there may be an effect of maintaining the degree of curing of the resin while increasing the refractive index.

In one embodiment, the composition for the second resin layer or the second resin layer may not include a thermosetting compound. The composition for the second resin layer or the second resin layer of the present invention can achieve improved hardness and improved flexibility by including a photoinitiator and a thermal initiator together in a UV curable compound without a thermosetting compound.

3rd resin layer

The third resin layer 400 has a lower refractive index than the second resin layer 200 , and has a lower refractive index than the first resin layer 100 . Through this, the third resin layer 400 may further enhance the antireflection effect of the optical film. The third resin layer 400 may have a refractive index of 1.2 to 1.5, for example, 1.25 to 1.4. Within the above range, it is possible to produce an anti-reflection effect when laminated on the first resin layer and the second resin layer.

The third resin layer 400 may be formed of a composition for the third resin layer including inorganic particles, a fluorine-containing monomer or oligomer thereof, a fluorine-free monomer or oligomer thereof, an initiator, and a fluorine-containing additive.

Since the inorganic particles have a hollow structure and have a low refractive index, the refractive index of the third resin layer may be lowered. The refractive index of the inorganic particles may be 1.5 or less, for example, 1.1 to 1.4. As the inorganic particles, hollow silica may be used. The inorganic particles may be untreated hollow particles that are not surface-treated, or surface-treated with UV-curable functional groups. The average particle diameter (D50) of the inorganic particles is smaller than the thickness of the third resin layer, and may be 10 nm to 200 nm, for example, 20 nm to 100 nm. In the above range, it may be included in the third resin layer, and optical properties such as haze, transmittance, and reflectance of the optical film may be improved.

The fluorine-containing monomer or oligomer thereof together with the inorganic particles lowers the refractive index of the third resin layer and forms a matrix of the third resin layer together with the fluorine-free monomer or oligomer thereof. The fluorine-containing monomer may include a fluorine-containing (meth)acrylate-based compound. The fluorine-containing monomer may include conventional compounds known to those skilled in the art.

The fluorine-free monomer or oligomer thereof forms a matrix of the third resin layer, and may include a UV curable compound. The fluorine-free monomer or oligomer thereof may be a (meth)acrylate-based compound having more than bifunctionality, for example, bifunctional to 10-functional. Specifically, the fluorine-free monomer may include a polyfunctional (meth)acrylate such as an ester of the above-described polyhydric alcohol and (meth)acrylic acid.

The initiator may include one or more of a photoinitiator and a thermal initiator. The photoinitiator and thermal initiator are the same as those described for the second resin layer.

The additive is to add an antifouling function and slimness to the third resin layer, and a conventional additive known to those skilled in the art may be used. The additive may include at least one of a fluorine-containing additive and a silicone-based additive. The fluorine-containing additive may be a UV curable fluorinated acrylic compound. For example, as the fluorine-containing additive, KY-1200 series (Shinyetsu Corporation) including KY-1203 can be used.

The composition for the third resin layer may further include conventional additives known to those skilled in the art. For example, the additive may further include, but is not limited to, an antifoaming agent, an antioxidant, a UV absorber, a light stabilizer, a leveling agent, and the like.

The composition for the third resin layer may further include a solvent to improve coating properties. The solvent may include at least one of methyl ethyl ketone, methyl isobutyl ketone, and ethylene glycol dimethyl ether.

In one embodiment, the composition for the third resin layer contains 20 wt% to 70 wt% of inorganic particles, 5 wt% to 50 wt% of a fluorine-containing monomer or oligomer thereof, 10 wt% to 55 wt% of a fluorine-free monomer or oligomer thereof % by weight, 1% to 5% by weight of an initiator, and 0.5% to 10% by weight of an additive. In the above range, it is possible to obtain a pencil hardness of 2H or more, an anti-fingerprint effect, solvent resistance, and scratch resistance. Preferably, the composition for the third resin layer comprises 40 wt% to 60 wt% of inorganic particles, 5 wt% to 40 wt% of a fluorine-containing monomer or oligomer thereof, 15 wt% to 50 wt% of a fluorine-free monomer or oligomer thereof based on solid content %, 1% to 4% by weight of an initiator, and 1% to 7% by weight of an additive.

The third resin layer 400 may have a thickness of 50 nm to 200 nm, preferably 80 nm to 150 nm. In the above range, there may be a pencil hardness of 2H or more, an anti-fingerprint effect, solvent resistance, and scratch resistance effect.

Hereinafter, the manufacturing method of the optical film of this invention is demonstrated.

The optical film forms a first resin layer on one surface of the base layer, applies a composition for a second resin layer on one surface of the first resin layer to form a coating layer, and sequentially passes through a drying zone and a UV irradiation zone to form the coating layer It can be formed by converting to the second resin layer and coating and curing the composition for the third resin layer on the second resin layer.

The first resin layer may be formed by a conventional method known to those skilled in the art.

A coating layer may be formed by applying the composition for the second resin layer to one surface of the first resin layer, that is, to the pattern portion of the first resin layer. The composition for the second resin layer is coated to completely cover the pattern portion of the first resin layer. The coating layer may be dried and cured by sequentially passing through the drying zone and the UV irradiation zone to form a second resin layer. The drying zone may include heat-treating the coating layer at 40° C. to 120° C., preferably 50° C. to 100° C. for 2 minutes to 30 minutes, preferably 4 minutes to 10 minutes. However, the heat treatment time and temperature in the drying zone may be adjusted according to the thickness of the coating layer, the constituents of the composition for the second resin layer, the content, and the like. The UV irradiation zone is a zone for irradiating UV to the coating layer that has passed through the drying zone. The UV irradiation zone emits 200 nm to 800 nm light at 100 mJ/cm ² to 1000mJ/cm ² It may include irradiating with an intensity of 2 .

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described.

The polarizing plate may include a polarizing film and an optical film of the present invention formed on one surface of the polarizing film. The polarizing film and the optical film may be adhered through an adhesive layer. Preferably, the optical film may be formed on the light emitting surface of the polarizing film.

The polarizing film may polarize light incident from the liquid crystal panel and transmit it through the optical film. In one embodiment, the polarizing film may include a polarizer. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The polarizer may have a thickness of 5 μm to 40 μm. Within the above range, it can be used for an optical display device. In another embodiment, the polarizing film may include a polarizer and a protective layer formed on at least one surface of the polarizer. The protective layer may protect the polarizer to increase reliability of the polarizer and increase mechanical strength of the polarizer. The protective layer may include one or more of an optically clear, protective film or protective coating layer. The protective layer is substantially the same as the base layer described above.

The optical display device of the present invention may include the polarizing plate of the present invention.

In one embodiment, the optical display device may be a liquid crystal display device, and the polarizing plate of the present invention may be included as a viewer-side polarizing plate with respect to the liquid crystal panel. The "viewing-side polarizing plate" is disposed opposite to the screen side, that is, the light source side with respect to the liquid crystal panel.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example One

( 1) For the second resin layer composition preparation

14.7 parts by weight of urethane acrylic resin UP111 (Entis) as a UV curable compound, 5.98 parts by weight of bisphenol acrylic resin M2200 (Miwon) as an aromatic UV curable compound as a UV curable compound, Irgacure 184 (BASF) as a photoinitiator , diketone) 0.91 parts by weight, thermal initiator V601 (WACO, Azo) 0.91 parts by weight, zirconia particle-containing sol SP40C (KC Tech) 81.8 parts by weight 22.68 parts by weight of propylene glycol monomethyl ether acetate After putting in 22.68 parts by weight, for 20 minutes A composition for a second resin layer was prepared by stirring. The composition for the second resin layer includes 23.2% by weight of a urethane-based UV-curable compound, 9.4% by weight of an aromatic UV-curable compound, 1.4% by weight of a photoinitiator, 1.4% by weight of a thermal initiator, and 64.6% by weight of zirconia particles, based on the solid content.

( 2) For the third resin layer composition preparation

After adding 13.8 parts by weight of a fluorine-free monomer M306 (TOAGOSEI) to 67.5 parts by weight of THRULYA 5320 (JGC Catalyst and chemicals LTD), a hollow silica-containing sol, it was completely dissolved to obtain a mixture. 12.0 parts by weight of AR-110 (DAIKIN Corporation), which is a fluorine-containing monomer, was added to the mixture and stirred for 5 minutes. To the mixture, 2.25 parts by weight of KY-1203 (Shinetsu Corporation), a fluorine-containing additive, was added and stirred for 5 minutes. After adding 0.45 parts by weight of Irgacure 127 (BASF) as a photoinitiator to the mixture, it was completely dissolved. A solvent mixture of 150.92 parts by weight of propylene glycol monomethyl ether acetate, 452.77 parts by weight of methyl ethyl ketone, and 794.3 parts by weight of methyl isobutyl ketone was added to the mixture, followed by stirring for 30 minutes to prepare a composition for a third resin layer. The composition for the third resin layer includes 45 wt% of hollow silica, 46 wt% of a fluorine-free monomer, 6 wt% of a fluorine-containing monomer, 1.5 wt% of a photoinitiator, and 1.5 wt% of a fluorine-containing additive based on solid content.

( 3) Optics film manufacturing

As a base layer, a UV-curable resin (SSC-P4450A, Shin-A T&C) is coated on the upper surface of a polyethylene terephthalate film (SKC, thickness: 40㎛) to a predetermined thickness, and an optical pattern and a flat part are alternately formed using a film An optical pattern and a flat part were applied to the coating layer, and the first resin layer was formed by UV curing with an amount of UV light of 500 mJ/cm ² . On one surface of the prepared first resin layer, the prepared composition for the second resin layer was coated with No. 26 Mayer bar. After drying at 80° C. for 2 minutes in the drying zone, UV 100 mJ/cm ² was irradiated under nitrogen atmosphere in the UV irradiation zone to form a second resin layer (flesh thickness: 10 μm). After coating the prepared composition for the third resin layer on the upper surface of the prepared second resin layer with Mayer bar No. 4, and drying it at 80° C. for 2 minutes in a drying zone, UV 150 mJ / under a nitrogen atmosphere in the UV irradiation zone cm ² was irradiated to form a third resin layer (thickness: 100 nm) to prepare an optical film.

( 4) Polarizer Produce

The polyvinyl alcohol film was uniaxially stretched 3 times at 60° C., iodine was adsorbed, and then stretched 2.5 times in an aqueous boric acid solution at 40° C. to prepare a polarizer (thickness: 25 μm). A polarizing plate was manufactured by laminating the COP film (Zeon, ZB12, thickness: 50 μm) on the lower surface of the polarizer and the optical film prepared in (3) on the upper surface of the polarizer with an adhesive. At this time, the lower surface of the polyethylene terephthalate film of the optical film was adhered to the upper surface of the polarizer.

Example 2

In Example 1, in the solvent mixture, THRULYA 5320 67.5 parts by weight, M306 13.8 parts by weight, AR-110 12.0 parts by weight, KY-1203 2.25 parts by weight, Irgacure 127 0.45 parts by weight, thermal initiator V601 (WACO) 0.225 parts by weight A composition for a third resin layer was prepared in the same manner as in Example 1, except that parts were used. In Example 1, an optical film and a polarizing plate were prepared in the same manner as in Example 1, except that the prepared composition for the third resin layer was used.

Example 3

In Example 1, 67.5 parts by weight of THRULYA 5320, 13.8 parts by weight of M306, 12.0 parts by weight of AR-110, 2.25 parts by weight of KY-1203, and 0.225 parts by weight of thermal initiator V601 (WACO) were used in the solvent mixture. A composition for a third resin layer was prepared in the same manner as in Example 1. In Example 1, an optical film and a polarizing plate were prepared in the same manner as in Example 1, except that the prepared composition for the third resin layer was used.

Example 4

In Example 1, 14.7 parts by weight of UP111, 5.98 parts by weight of M2200, 0.91 parts by weight of Iragcure 819 (BASF, phosphorus) as a photoinitiator, 0.91 parts by weight of BPO (Samjeon, organic peroxide) as a thermal initiator, sol containing zirconia particles A composition for a second resin layer was prepared in the same manner as in Example 1, except that 81.8 parts by weight of SP40C was used. The composition for the second resin layer contains 23.2% by weight of a urethane-based UV-curable compound, 9.4% by weight of an aromatic UV-curable compound, 1.4% by weight of a photoinitiator, 1.4% by weight of a thermal initiator, and 64.6% by weight of zirconia particles, based on the solid content. In Example 1, an optical film and a polarizing plate were prepared in the same manner as in Example 1, except that the prepared composition for the second resin layer was used.

comparative example One

In Example 1, 14.7 parts by weight of UP111, 5.98 parts by weight of M2200, 1.82 parts by weight of Irgacure 184, and 81.8 parts by weight of sol SP40C containing zirconia particles were used in the same manner as in Example 1, except that the composition for the second resin layer (thermal initiator) does not contain) was prepared. The composition for the second resin layer includes 23.2% by weight of a urethane-based UV-curable compound, 9.4% by weight of an aromatic UV-curable compound, 2.8% by weight of a photoinitiator, and 64.6% by weight of zirconia particles, based on solid content. In Example 1, an optical film and a polarizing plate were prepared in the same manner as in Example 1, except that the prepared composition for the second resin layer was used.

comparative example 2

In Example 1, 14.7 parts by weight of UP111, 5.98 parts by weight of M2200, 1.82 parts by weight of V601, and 81.8 parts by weight of sol SP40C containing zirconia particles were used in the same manner as in Example 1, except that the composition for the second resin layer (photoinitiator was not included) was prepared. The composition for the second resin layer includes 23.2% by weight of a urethane-based UV-curable compound, 9.4% by weight of an aromatic UV-curable compound, 2.8% by weight of a thermal initiator, and 64.6% by weight of zirconia particles, based on solid content. In Example 1, an optical film and a polarizing plate were prepared in the same manner as in Example 1, except that the prepared composition for the second resin layer was used.

Specific specifications of the pattern part among the optical films of Examples and Comparative Examples are shown in Table 1 below.

optical pattern shape Maximum height (H) (㎛) Max Width (W)
(μm) Width of the first side (A) (㎛) base angle
(°) Width (L)
(μm) cycle (P)
(μm) Cut-prism
(trapezoidal, embossed pattern) 7 7 6 86 7 14

The following physical properties were evaluated for the optical films of Examples and Comparative Examples, and the results are shown in Table 2 below.

(1) Hardness: Measure the hardness of the outermost layer of the optical film by the JIS K5400 method using a pencil hardness tester (Heidon). When measuring the hardness, pencils of Mitsubishi's 6B to 9H were used. The pencil load on the outermost layer was 500 g, the pencil drawing angle was 45°, and the pencil drawing speed was 48 mm/min. If scratch occurs more than once after evaluating 5 times, it is measured using a pencil of the lower level of pencil hardness, and when evaluated 5 times, it is the maximum pencil hardness value when there are no scratches in all 5 times.

(2) Flexibility (unit: mm): Whether cracks occurred in the optical film (width x length, 1 cm x 10 cm) was visually evaluated with a vernier caliper for a curvature test. The optical film was rolled up in a state in which the base layer of the optical film was in contact with the jig for measuring the radius of curvature. The radius of the jig was measured while decreasing from a large value to a small value. The minimum radius of the jig where cracks do not occur was determined as the radius of curvature in the evaluation of flexibility.

(3) Minimum reflectance (unit: %): SCI with a spectrophotometer (Spectrophotometer, Konica Minolta, CM-3600A) for a specimen prepared by laminating a black acrylic sheet (Nitto Jushi Kogyo, CLAREX) on the lower surface of the optical film base layer In the reflection mode (light source: D65 light source, light source aperture: Ф8mm), it means the Y value among reflectances measured at a wavelength of 360 nm to 740 nm.

Example comparative example One 2 3 4 One 2 A 1.315 1.320 1.310 1.315 1.315 1.315 B 1.632 1.632 1.632 1.625 1.629 1.615 C 1.475 1.475 1.475 1.475 1.475 1.475 pattern part ○ ○ ○ ○ ○ ○ pencil hardness 3H 3H 2H 2H 2H H Flexibility (mm) 5 5 5 5 8 5 Minimum reflectance (%) 0.92 1.1 1.03 1.07 1.15 1.13

*In Table 2 above,

A is the refractive index of the third resin layer,

B is the refractive index of the second resin layer,

C is the refractive index of the first resin layer

As shown in Table 2, the optical film of the present invention includes both a photoinitiator and a thermal initiator in the second resin layer in the optical film having an embossed optical pattern and a flat portion, thereby lowering the minimum reflectance while lowering the hardness and flexibility were improved at the same time. In addition, although not shown in Table 2, the optical film of the present invention was excellent in the flexibility of the optical film when the flexibility was evaluated in both the longitudinal direction and the width direction of the embossed optical pattern.

On the other hand, Comparative Example 1 having a second resin layer including a photoinitiator but not including a thermal initiator had a weak effect of improving flexibility. Comparative Example 2 having a second resin layer including a thermal initiator but not including a photoinitiator had a weak hardness improvement effect.

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (20)

base layer; And as an optical film comprising a first resin layer, a second resin layer and a third resin layer sequentially formed on the upper surface of the base layer,
at least one embossed optical pattern at the interface between the first resin layer and the second resin layer; and a flat portion formed between the embossed optical pattern and the embossed optical pattern immediately adjacent thereto,
The first resin layer has a lower refractive index than the second resin layer,
The second resin layer is formed of a composition for a second resin layer comprising a UV curable compound, a photoinitiator and a thermal initiator,
The composition for the second resin layer or the second resin layer does not contain a thermosetting compound,
The photoinitiator is included in 0.1 wt% to 5 wt% of the second resin layer,
The thermal initiator is included in an amount of 0.1% to 3% by weight of the second resin layer,
The optical film has a pencil hardness of 2H or more, and the optical film has a radius of curvature of 5 mm or less, respectively, when the flexibility is evaluated in both the longitudinal and width directions of the embossed optical pattern.
delete delete The optical film of claim 1, wherein the photoinitiator includes at least one of phosphorus-based and diketone-based.
The optical film of claim 1 , wherein the thermal initiator includes at least one of azo-based and organic peroxide-based.
The optical film of claim 1 , wherein the UV curable compound includes at least one of a urethane (meth)acrylic compound and an aromatic (meth)acrylic compound.
The optical film of claim 1, wherein the second resin layer further comprises high refractive index particles having a refractive index higher than that of the first resin layer.
The optical film of claim 7 , wherein the high refractive index particles include at least one of zirconia and titania.
The optical film of claim 7, wherein the high refractive index particles are included in an amount of 20 wt% to 75 wt% of the second resin layer.
The optical film of claim 1, wherein the embossed optical pattern has a cross-section of a trapezoidal, rectangular or square optical pattern.
The optical film of claim 1, wherein the embossed optical pattern is formed in a stripe-like elongated form in the longitudinal direction of the embossed optical pattern.
The optical film of claim 1, wherein the difference in refractive index between the second resin layer and the first resin layer is 0.1 or more.
The optical film of claim 1, wherein the third resin layer has a refractive index lower than that of the first resin layer and the second resin layer, respectively.
According to claim 1, wherein the third resin layer is formed of a composition for the third resin layer comprising inorganic particles, a fluorine-containing monomer or oligomer thereof, a fluorine-free monomer or oligomer thereof, an initiator and a fluorine-containing additive, optical film.
The optical film of claim 14 , wherein the inorganic particles comprise hollow silica.
The optical film according to claim 14, wherein the inorganic particles are included in an amount of 20 wt% to 70 wt% based on the solid content in the composition for the third resin layer.
delete delete polarizing film; and
A polarizing plate comprising the optical film of any one of claims 1 and 4 to 16, formed on one surface of the polarizing film.
An optical display device comprising the polarizing plate of claim 19.

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