JP7057865B2 - Anti-reflection film and its manufacturing method, and image display device - Google Patents

Description

The present invention relates to an antireflection film and a method for producing the same, and an image display device including the antireflection film.

An antireflection film may be provided on the surface of an image display device such as a liquid crystal display or an organic EL display for the purpose of improving the visibility of the displayed image. The antireflection film includes an antireflection layer composed of a plurality of thin films having different refractive indexes on a film base material. An antireflection film using an inorganic thin film such as an inorganic oxide as the thin film forming the antireflection layer can easily adjust the refractive index and the film thickness, so that high antireflection characteristics can be realized.

Since the antireflection film is arranged on the outermost surface of the image display device, a hard coat layer may be provided on the antireflection layer forming surface of the film substrate for the purpose of preventing damage due to contact from the outside. However, in general, the hard coat layer formed of an organic substance and the inorganic thin film have a small adhesion between layers, and delamination may occur. In particular, in an environment exposed to ultraviolet rays such as outdoors, the problem of delamination tends to become noticeable.

In Patent Document 1, a primer layer made of silicon oxide (SiO _x ; 0 <x <2) in an oxygen-deficient state (non-stoichiometric composition) is formed on the hard coat layer, and an antireflection layer is formed on the primer layer. It is described that the adhesion of the antireflection layer is improved by the above.

International Publication No. 2016/190415

A primer layer made of silicon oxide having a non-stoichiometric composition is formed by reactive sputtering using a silicon target. According to the studies by the present inventors, the antireflection film in which a silicon oxide thin film is provided as a primer layer between the hard coat layer and the antireflection layer has unstable characteristics such as adhesion and transparency of the antireflection layer. It turned out to be. In view of these problems, it is an object of the present invention to provide an antireflection film having excellent quality stability such as adhesion and transparency.

The present invention relates to an antireflection film and a method for producing the same. The antireflection film is used, for example, by arranging it on the visible surface of an image display device.

The antireflection film includes a hard coat film having a hard coat layer on one main surface of a film base material, a primer layer provided in contact with the hard coat layer, and an antireflection layer provided in contact with the primer layer. And. The hard coat layer may contain fine particles in addition to the binder resin.

The primer layer arranged between the hard coat layer and the antireflection layer is a metal oxide layer containing metal oxides such as In and Sn. As the metal oxide, an indium-based oxide containing indium oxide as a main oxide is preferable, and indium tin oxide (ITO) is particularly preferable. The primer layer is formed by a sputtering method using, for example, an oxide target. The thickness of the primer layer is preferably about 0.5 to 30 nm.

The antireflection layer is a laminate of a plurality of thin films having different refractive indexes, and each thin film may be an inorganic oxide thin film. The antireflection layer is formed by, for example, a sputtering method. The antireflection layer can also be formed into a film by reactive sputtering.

Since the primer layer arranged between the hard coat layer and the antireflection layer is a metal oxide layer, there is little fluctuation or variation in the oxidation state, and the antireflection film with excellent quality such as adhesion and transparency is stable. Can be provided.

It is sectional drawing which shows the laminated form of the antireflection film.

FIG. 1 is a cross-sectional view showing an example of a laminated structure of an antireflection film. The antireflection film 100 includes a hard coat film 1 having a hard coat layer 11 provided on one main surface of the film base material 10, a primer layer 3 in contact with the hard coat layer 11, and an antireflection layer 5 in contact with the primer layer. To prepare for. The antireflection layer 5 is a laminate of two or more layers of inorganic thin films having different refractive indexes. In the antireflection film 100 shown in FIG. 1, the antireflection layer 5 has a structure in which high refractive index layers 51 and 53 and low refractive index layers 52 and 54 are alternately laminated.

[Hardcourt film]
<Film base material>
As the film base material 10 of the hard coat film 1, for example, a transparent film is used. The visible light transmittance of the transparent film is preferably 80% or more, more preferably 90% or more. As the resin material constituting the transparent film, for example, a resin material having excellent transparency, mechanical strength, and thermal stability is preferable. Specific examples of the resin material include cellulose-based resins such as triacetyl cellulose, polyester-based resins, polyether sulfone-based resins, polysulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, and polyolefin-based resins, (meth). Examples thereof include acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

The film substrate 10 does not necessarily have to be transparent. Further, as the film base material 10, a laminate of a plurality of films may be used. For example, as will be described later, a polarizing plate provided with a protective film on the surface of the polarizing element may be used as the film base material 10.

The thickness of the film base material 10 is not particularly limited, but is preferably about 5 to 300 μm, more preferably 10 to 250 μm, and even more preferably 20 to 200 μm from the viewpoint of workability such as strength and handleability, and thin layer property.

<Hard coat layer>
The hard coat film 1 is formed by providing the hard coat layer 11 on the main surface of the film base material 10. The hard coat layer is a curable resin layer, and is formed by applying a composition containing a curable resin onto a film substrate and curing the resin component. The hard coat layer may contain fine particles in addition to the cured resin.

(Curable resin)
As the curable resin (binder resin) of the hard coat layer 11, a curable resin such as a thermosetting resin, a photocurable resin, and an electron beam curable resin is preferably used. Examples of the curable resin include polyester-based, acrylic-based, urethane-based, acrylic-urethane-based, amide-based, silicone-based, silicate-based, epoxy-based, melamine-based, oxetane-based, and acrylic urethane-based. Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferable, and acrylic urethane resins are particularly preferable because they have high hardness and can be photocured.

The photocurable resin composition contains a polyfunctional compound having two or more photopolymerizable (preferably UV-polymerizable) functional groups. The polyfunctional compound may be a monomer or an oligomer. As the photopolymerizable polyfunctional compound, a compound containing two or more (meth) acryloyl groups in one molecule is preferably used.

Specific examples of the polyfunctional compound having two or more (meth) acryloyl groups in one molecule include tricyclodecanedimethanol diacrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and trimethylol. Propanetriacrylate, pentaerythritol tetra (meth) acrylate, dimethylolpropanetotetraacrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol (meth) acrylate, 1,9-nonanediol diacrylate, 1, 10-decanediol (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, dipropylene glycol diacrylate, isocyanuric acid tri (meth) acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetra Examples thereof include acrylates and oligomers or prepolymers thereof. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacrylic.

A polyfunctional compound having two or more (meth) acryloyl groups in one molecule may have a hydroxyl group. By using a polyfunctional compound containing a hydroxyl group, the adhesion between the film substrate and the hard coat layer tends to be improved. Examples of the compound having a hydroxyl group and two or more (meth) acryloyl groups in one molecule include pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate.

The acrylic urethane resin contains a monomer or oligomer of urethane (meth) acrylate as a polyfunctional compound. The number of (meth) acryloyl groups contained in the urethane (meth) acrylate is preferably 3 or more, more preferably 4 to 15, and even more preferably 6 to 12. The molecular weight of the urethane (meth) acrylate oligomer is, for example, 3000 or less, preferably 500 to 2500, and more preferably 800 to 2000. Urethane (meth) acrylate is obtained, for example, by reacting hydroxy (meth) acrylate obtained from (meth) acrylic acid or (meth) acrylic acid ester with a polyol with diisocyanate.

The content of the polyfunctional compound in the composition for forming a hard coat layer is preferably 50 parts by weight or more with respect to 100 parts by weight in total of the resin components (monomers, oligomers and prepolymers forming the binder resin by curing). 60 parts by weight or more is more preferable, and 70 parts by weight or more is further preferable. When the content of the polyfunctional monomer is in the above range, the hardness of the hard coat layer tends to be increased.

(Fine particles)
Since the hard coat layer 11 contains fine particles, it is possible to adjust the surface shape, impart optical characteristics such as antiglare property, and improve the adhesion of the antireflection layer.

The fine particles include inorganic oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide, glass fine particles, polymethylmethacrylate, polystyrene, polyurethane, and acrylic-styrene copolymer. , Crosslinked or uncrosslinked organic fine particles made of transparent polymers such as benzoguanamine, melamine and polycarbonate can be used without particular limitation.

The average particle size (average primary particle size) of the fine particles is preferably about 10 nm to 10 μm. The fine particles have an average particle diameter of about 0.5 μm to 10 μm or an average particle diameter on the order of μm (hereinafter, may be referred to as “microparticles”) depending on the particle size, and have an average particle diameter of about 10 nm to 100 nm. It can be roughly divided into fine particles having a particle size (hereinafter sometimes referred to as “nanoparticles”) and fine particles having a particle size intermediate between microparticles and nanoparticles.

When the hard coat layer 11 contains nanoparticles, fine irregularities are formed on the surface, and the adhesion between the hard coat layer 11 and the primer layer 3 and the antireflection layer 5 tends to be improved. As the nanoparticles, inorganic fine particles are preferable, and inorganic oxide fine particles are particularly preferable. Among them, silica particles are preferable because they have a low refractive index and can reduce the difference in refractive index from the binder resin.

From the viewpoint of forming an uneven shape having excellent adhesion to the inorganic thin film on the surface of the hard coat layer 11, the average primary particle diameter of the nanoparticles is preferably 20 to 80 nm, more preferably 25 to 70 nm, and 30 to 60 nm. More preferred. Further, from the viewpoint of suppressing the coloring of the reflected light on the surface of the hard coat layer, the average primary particle diameter of the nanoparticles is preferably 55 nm or less, more preferably 50 nm or less, still more preferably 45 nm or less. The average primary particle size is a weight average particle size measured by the Coultercount method.

The amount of nanoparticles in the hard coat layer 11 may be about 1 to 150 parts by weight with respect to 100 parts by weight of the binder resin. From the viewpoint of forming a surface shape excellent in adhesion to the inorganic thin film on the surface of the hard coat layer 11, the content of nanoparticles in the hard coat layer 11 is 20 to 100 weight by weight with respect to 100 parts by weight of the binder resin. Parts are preferable, 25 to 90 parts by weight are more preferable, and 30 to 80 parts by weight are further preferable.

When the hard coat layer 11 contains microparticles, protrusions having a diameter on the order of submicron or μm are formed on the surface of the hard coat layer 11 and the surface of the thin film formed on the surface, and antiglare is imparted. .. The microparticles preferably have a small difference in refractive index from the binder resin of the hard coat layer, and preferably low refractive index inorganic oxide particles such as silica or polymer fine particles.

From the viewpoint of forming a surface shape suitable for imparting antiglare properties, the average primary particle diameter of the microparticles is preferably 1 to 8 μm, more preferably 2 to 5 μm. When the particle size is small, the antiglare property tends to be insufficient, and when the particle size is large, the sharpness of the image tends to decrease. The content of the microparticles in the hard coat layer 11 is not particularly limited, but is preferably 1 to 15 parts by weight, more preferably 2 to 10 parts by weight, still more preferably 3 to 8 parts by weight, based on 100 parts by weight of the binder resin.

The hardcourt layer 11 may contain only one of nanoparticles and microparticles, or may contain both. Further, it may contain fine particles having a particle size intermediate between nanoparticles and microparticles.

(Formation of hard coat layer)
The composition for forming a hard coat layer contains the above-mentioned binder resin component, and if necessary, contains a solvent capable of dissolving the binder resin component. As described above, the composition for forming a hard coat layer may contain fine particles. When the binder resin component is a photocurable resin, it is preferable that the composition contains a photopolymerization initiator. In addition to the above, the composition for forming a hard coat layer includes a leveling agent, a thixotropic agent, an antistatic agent, an antiblocking agent, a dispersant, a dispersion stabilizer, an antioxidant, an ultraviolet absorber, an antifoaming agent, and a thickener. , Surfactants, lubricants and other additives may be included.

A hardcourt layer is formed by applying a composition for forming a hardcoat layer on a film substrate, removing a solvent and curing the resin, if necessary. As a method for applying the composition for forming a hard coat layer, any appropriate method such as a bar coat method, a roll coat method, a gravure coat method, a rod coat method, a slot orifice coat method, a curtain coat method, a fountain coat method, a comma coat method, etc. is appropriate. Method can be adopted. The heating temperature after coating may be set to an appropriate temperature according to the composition of the hard coat layer forming composition and the like, and is, for example, about 50 ° C to 150 ° C. When the binder resin component is a photocurable resin, photocuring is performed by irradiating with active energy rays such as ultraviolet rays. The integrated light amount of the irradiation light is preferably about 100 to 500 mJ / cm ² .

The thickness of the hard coat layer 11 is not particularly limited, but is preferably about 1 to 10 μm, more preferably 2 to 9 μm, and even more preferably 3 to 8 μm from the viewpoint of achieving high hardness and appropriately controlling the surface shape.

Before forming the primer layer 3 and the antireflection layer 5 on the hard coat layer 11, the hard coat layer 11 is used for the purpose of further improving the adhesion between the hard coat layer 11 and the primer layer 3 and the antireflection layer 5. Surface treatment may be performed. Examples of the surface treatment include surface modification treatments such as corona treatment, plasma treatment, frame treatment, ozone treatment, primer treatment, glow treatment, alkali treatment, acid treatment, and treatment with a coupling agent. Vacuum plasma treatment may be performed as the surface treatment. The surface roughness of the hard coat layer can also be adjusted by vacuum plasma treatment. For example, when vacuum plasma treatment is performed with high discharge power, the surface unevenness of the surface of the hard coat layer becomes large, and the adhesion to the inorganic thin film tends to be improved.

<Primer layer>
A primer layer 3 is formed on the hard coat layer 11, and an antireflection layer 5 is formed on the primer layer 3. By providing the primer layer 3 in contact with the hard coat layer 11 and providing the antireflection layer 5 in contact with the primer layer 3, the adhesion between the layers is excellent and reflection is achieved even when exposed to light such as ultraviolet rays for a long time. An antireflection film can be obtained in which the prevention layer is less likely to be peeled off.

The primer layer 3 is a metal oxide thin film. The term "metal" here is a concept that does not include metalloids such as silicon. Metals include Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Examples thereof include Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Sn, Pb and the like. The metal oxide layer may be a composite oxide, and may contain metalloids such as B, C, Ge, P, As, Sb, Be, Se, Te, Po, and At as dopant elements. Specific examples of the metal oxide containing Sb, which is a semimetal as a dopant, include antimony-doped tin oxide (ATO).

Among the above, the primer layer preferably contains an oxide of one or more metals selected from the group consisting of In and Sn because of its high transparency, and one of In and Sn is used as the main metal element. Metal oxides are preferred. Of these, indium-based oxides containing indium oxide as a main component are preferable because they have high transparency and excellent optical stability.

The indium-based oxide preferably contains 60% by weight or more of indium oxide. Specific examples of the indium-based oxide include indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Among them, ITO is preferable because it is highly transparent and has excellent adhesion to the hard coat layer. The amount of indium oxide in ITO is preferably about 80 to 98%.

The thickness of the primer layer 3 is, for example, about 0.5 to 30 nm, preferably 1 to 25 nm, and may be 2 nm or more or 3 nm or more. When the film thickness of the primer layer is within the above range, the adhesion to the hard coat layer 11 can be improved, and the light transmittance of the antireflection film can be improved.

The primer layer of the antireflection film may be a dielectric or a conductor. Even when the metal oxide of the primer layer 3 is a conductive oxide such as ITO, the primer layer does not require conductivity, so that a large thickness unlike a transparent electrode is not required. From the viewpoint of increasing the light transmittance, it is preferable that the primer layer 3 has a small thickness as long as the adhesion to the hard coat layer 11 and the antireflection layer 5 can be ensured. The thickness of the primer layer 3 may be 20 nm or less, 15 nm or less, 10 nm or less, or 8 nm or less.

<Anti-reflection layer>
The antireflection layer 5 is a laminated body of a plurality of thin films having different refractive indexes. Generally, in the antireflection layer, the optical film thickness (product of refractive index and thickness) of the thin film is adjusted so that the inverted phases of the incident light and the reflected light cancel each other out. The multi-layered laminate of a plurality of thin films having different refractive indexes can reduce the reflectance in a wide wavelength range of visible light. As the thin film constituting the antireflection layer 5, an inorganic material is preferable, and a ceramic material composed of a metal or semi-metal oxide, a nitride, a fluoride or the like is preferable, and among them, a metal or semi-metal oxide (inorganic oxide) is preferable. Is preferable.

The antireflection layer 5 is preferably an alternating laminate of a high refractive index layer and a low refractive index layer. In order to reduce reflection at the air interface, the thin film 54 provided as the outermost layer of the antireflection layer 5 (the layer farthest from the hard coat film 1) is preferably a low refractive index layer.

The high refractive index layers 51 and 53 have, for example, a refractive index of 1.9 or more, preferably 2.0 or more. Examples of the high refractive index material include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), antimonated tin oxide (ATO) and the like. Of these, titanium oxide or niobium oxide is preferable. The low refractive index layers 52 and 54 have, for example, a refractive index of 1.6 or less, preferably 1.5 or less. Examples of the low refractive index material include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, lanthanum fluoride and the like. Of these, silicon oxide is preferable. In particular, it is preferable to alternately stack niobium oxide (Nb ₂ O ₅ ) thin films 51 and 53 as a high refractive index layer and silicon oxide (SiO ₂ ) thin films 52 and 54 as a low refractive index layer. In addition to the low refractive index layer and the high refractive index layer, a medium refractive index layer having a refractive index of about 1.6 to 1.9 may be provided.

The film thicknesses of the high refractive index layer and the low refractive index layer are each about 5 to 200 nm, preferably about 15 to 150 μm. The film thickness of each layer may be designed so that the reflectance of visible light becomes small according to the refractive index, the laminated structure, and the like. For example, as a laminated structure of a high refractive index layer and a low refractive index layer, a high refractive index layer 51 having an optical film thickness of about 25 nm to 55 nm and a low refractive index layer having an optical film thickness of about 35 nm to 55 nm are formed from the hard coat film 1 side. 52, a high refractive index layer 53 having an optical film thickness of about 80 nm to 240 nm, and a low refractive index layer 54 having an optical film thickness of about 120 nm to 150 nm can be mentioned. The antireflection layer is not limited to the four-layer structure, and may be a two-layer structure, a three-layer structure, a five-layer structure, or a laminated structure of six or more layers.

<Film formation of primer layer and antireflection layer>
The method for forming the thin film constituting the primer layer 3 and the antireflection layer 5 is not particularly limited, and either a wet coating method or a dry coating method may be used. Since a thin film having a uniform film thickness can be formed, a dry coating method such as vacuum vapor deposition, CVD, sputtering, or electron beam steaming is preferable. Of these, the sputtering method is preferable because it has excellent film thickness uniformity and easily forms a dense film.

In the sputtering method, the roll-to-roll method enables continuous film formation of a thin film while transporting the film substrate in one direction (longitudinal direction). Therefore, the productivity of the antireflection film including the primer layer 3 and the antireflection layer 5 composed of a plurality of thin films on the hard coat film 1 can be improved.

In the sputtering method, the film is formed while introducing an inert gas such as argon and, if necessary, a reactive gas such as oxygen into the chamber. The film formation of the oxide layer by the sputtering method can be carried out by either a method using an oxide target or a reactive sputtering method using a (metalloid) metal target.

Since the inorganic oxide can be formed at a high rate, the thin film constituting the antireflection layer 5 is preferably formed by reactive sputtering using a metal or semimetal target. As the sputtering power source used for reactive sputtering, DC or MF-AC is preferable.

In the reactive sputtering, the film is formed while introducing an inert gas such as argon and a reactive gas such as oxygen into the chamber. In reactive sputtering, it is preferable to adjust the amount of oxygen so as to be an intermediate transition region between the metal region and the oxide region. When a film is formed in a metal region, the amount of oxygen in the obtained film is small compared to the stoichiometric composition, resulting in a state of oxygen deficiency, and the antireflection layer tends to have a metallic luster and its transparency tends to decrease. Further, in the oxide region where the amount of oxygen is large, the film formation rate tends to be extremely lowered.

By adjusting the amount of oxygen so that the sputter film formation becomes the transition region, the oxide film can be formed at a high rate. As a method of controlling the amount of oxygen introduced so that the film forming mode is in the transition region, a plasma emission monitoring method (PEM method) that detects the plasma emission intensity of the discharge and controls the amount of gas introduced into the film forming chamber is used. Can be mentioned. In PEM, control is performed by detecting the plasma emission intensity and feeding it back to the amount of oxygen introduced. For example, the film formation in the transition region can be maintained by setting the control value (set point) of the emission intensity within a predetermined range, performing PEM control, and adjusting the amount of oxygen introduced. Control may be performed by an impedance method that controls the amount of oxygen introduced so that the plasma impedance becomes constant, that is, the discharge voltage becomes constant.

It is preferable to use an oxide target for forming the primer layer 3. Reactive sputter using a metal target has the advantage of high film formation rate, but the film quality may change due to a slight change in the amount of reactive gas introduced such as oxygen. On the other hand, when the oxide target is used, the film quality of the primer layer is stabilized because the film quality does not change much even when the film forming conditions such as the amount of oxygen introduced change. Further, if a conductive oxide target such as ITO is used, film formation at a high rate is possible by DC sputtering.

The substrate temperature at the time of sputter-forming the primer layer is about −30 to 150 ° C., and is not particularly limited as long as the hard coat film as the substrate material has durability. The pressure and power density when the primer layer is sputter-deposited can be appropriately set according to the type of target and the film thickness of the primer layer.

When the primer layer 3 is formed by sputtering using an oxide target, it is preferable to introduce an oxidizing gas such as oxygen in addition to an inert gas such as argon. By introducing oxygen, oxygen desorbed from the target during sputtering is supplemented, so that an oxide thin film having a stoichiometric composition is likely to be formed, and transparency tends to be improved. Further, as the amount of oxygen introduced during the sputtering film formation increases, the adhesion of the antireflection layer tends to improve. The amount of oxygen introduced during sputter film formation is, for example, about 0.1 to 100 parts by volume, preferably 0.3 parts by volume or more, and more preferably 0.5 parts by volume or more with respect to 100 parts by volume of the inert gas. .. From the viewpoint of enhancing the adhesion of the antireflection layer, the amount of oxygen introduced during sputter film formation is preferably 1 part by volume or more, more preferably 5 parts by volume or more, and 10 parts by volume or more with respect to 100 parts by volume of the inert gas. Is more preferable, and it may be 15 parts by volume or more, 20 parts by volume or more, or 25 parts by volume or more. The amount of oxygen introduced during sputter film formation is 80 parts by volume or less, 70 parts by volume or less, 60 parts by volume or less, 50 parts by volume or less, 40 parts by volume or less, or 30 parts by volume or less with respect to 100 parts by volume of the inert gas. There may be.

In reactive sputtering using a metal target, if the amount of oxygen introduced is small, the oxide may have a non-stoichiometric composition and the transparency of the primer layer may decrease. Oxygen deficiency is slight even when no introduction is made, and a significant decrease in transparency can be avoided. When forming a transparent electrode, the conductivity tends to decrease if the amount of oxygen introduced is excessively large. However, as described above, the primer layer is not required to have conductivity, so even if the amount of oxygen introduced is large, the conductivity is particularly high. No problem arises. Rather, as the amount of oxygen introduced increases, the adhesion of the antireflection layer tends to improve, so that the amount of oxygen introduced is larger than the general conditions for forming a conductive film such as a transparent electrode. It is preferable to form a primer layer.

In an antireflection film in which silicon oxide is provided as a primer layer between the hard coat layer and the antireflection layer, the film quality of the primer layer fluctuates greatly, and the adhesion and transparency tend to decrease. One of the factors that change the film quality of the silicon oxide primer layer is that it is not easy to precisely control the composition (value of x) of SiO _x , which is an oxide of Si, which is a metalloid.

SiO _x is formed into a film by reactive sputtering using a Si target, but the composition changes due to a slight difference in film forming conditions. When the amount of oxygen is small, the transparency tends to decrease, and when the amount of oxygen is large, SiO ₂ having no oxygen deficiency (stoichiometric composition) is generated, and the adhesion of the antireflection layer decreases. Tend. When an oxide target is used, the amount of oxygen can be appropriately controlled while monitoring the reaction by the above-mentioned PEM control or the like in the film formation of a complete oxide, but in the film formation of an oxide having a non-stoichiometric composition, it is incorporated into a thin film. It is not easy to control the amount of oxygen to be constant, and the characteristics tend to vary.

As described above, when the metal oxide primer layer such as ITO is formed by using the oxide target, the characteristic change due to the deviation of the oxygen amount is unlikely to occur, and the fine adjustment of the oxygen amount is not required. Therefore, it is possible to provide an antireflection film having stable quality such as transparency and adhesion of the antireflection layer. Further, by increasing the amount of oxygen introduced during the formation of the primer layer, it is possible to realize better adhesion than the SiO _x primer layer.

[Anti-fouling layer]
The antireflection film may be provided with an additional functional layer on the antireflection layer 5. When the silicon oxide layer is arranged as the low refractive index layer 54 on the outermost surface of the antireflection layer 5, the wettability of the silicon oxide is high, and contaminants such as fingerprints and hand stains are likely to adhere. Therefore, an antifouling layer (not shown) may be provided on the antireflection layer 5 for the purpose of preventing contamination from the external environment and facilitating the removal of adhering contaminants.

When the antifouling layer is provided on the surface of the antireflection film, the difference in refractive index between the low refractive index layer 54 on the outermost surface of the antireflection layer 5 and the antifouling layer is small from the viewpoint of reducing reflection at the interface. preferable. The refractive index of the antifouling layer is preferably 1.6 or less, more preferably 1.55 or less. As the material of the antifouling layer, a fluorine group-containing silane compound, a fluorine group-containing organic compound, or the like is preferable. The antifouling layer can be formed by a wet method such as a reverse coating method, a die coating method, a gravure coating method, a dry method such as a CVD method, or the like. The thickness of the antifouling layer is usually about 1 to 100 nm, preferably 2 to 50 nm, and more preferably 3 to 30 nm.

[Usage form of antireflection film]
The antireflection film is used by arranging it on the surface of an image display device such as a liquid crystal display or an organic EL display. For example, by arranging the antireflection film on the visible side surface of the panel including the image display medium such as a liquid crystal cell or an organic EL cell, the reflection of external light can be reduced and the visibility of the image display device can be improved.

The antireflection film may be laminated with another film. For example, a polarizing plate with an antireflection layer can be formed by attaching a polarizing element to the non-formed surface of the hard coat layer of the film substrate 10.

As the deflector, a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene / vinyl acetate copolymerization system partially saponified film, and a dichroic substance such as iodine or a dichroic dye are used. Examples thereof include a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrogenated product of polyvinyl chloride, which is uniaxially stretched by adsorbing. Among them, since it has a high degree of polarization, polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol is adsorbed with a dichroic substance such as iodine or a dichroic dye and oriented in a predetermined direction. Alcohol (PVA) -based modulators are preferred.

A transparent protective film may be provided on the surface of the polarizing element for the purpose of protecting the polarizing element. The transparent protective film may be bonded to only one surface of the polarizing element, or may be bonded to both sides. Generally, a transparent protective film is provided on the surface of the polarizing element opposite to the surface on which the antireflection film is attached. Since the antireflection film also functions as a transparent protective film on the surface of the polarizing element with the antireflection film, it is not necessary to provide a transparent protective film, but a transparent protective film is provided between the polarizing element and the antireflection film. It may have been.

As the material of the transparent protective film, the same material as described above is preferably used as the material of the transparent film base material. It is preferable to use an adhesive for bonding the splitter and the transparent film. Adhesives are based on acrylic polymers, silicon polymers, polyesters, polyurethanes, polyamides, polyvinyl alcohols, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, fluoropolymers, rubber polymers, etc. A polymer can be appropriately selected and used. A polyvinyl alcohol-based adhesive is preferably used for adhering the PVA-based polarizing element.

Hereinafter, the present invention will be described in more detail with reference to specific examples of an antireflection film in which a primer layer is provided between a hard coat layer and an antireflection layer, but the present invention is not limited to the following specific examples. not.

[Making a hard coat film]
The amount of silica particles in the ultraviolet curable acrylic resin composition (manufactured by DIC, trade name "GRANDIC PC-1070", refractive index at a wavelength of 405 nm: 1.55) is 25 parts by weight with respect to 100 parts by weight of the resin component. Organo silica sol (“MEK-ST-L” manufactured by Nissan Chemical Co., Ltd., average primary particle size of silica particles (inorganic filler): 50 nm, particle size distribution of silica particles: 30 nm to 130 nm, solid content 30% by weight) is added to the mixture. And mixed to prepare a composition for forming a hard coat layer.

The above composition was applied to one side of a triacetyl cellulose film having a thickness of 40 μm so as to have a thickness of 6 μm after drying, and dried at 80 ° C. for 3 minutes. Then, using a high-pressure mercury lamp, ultraviolet rays having an integrated light intensity of 200 mJ / cm ² were irradiated to cure the coating layer and form a hard coat layer.

[Anti-reflection film 1A]
<Surface treatment>
The surface of the hard coat layer was subjected to argon plasma treatment with a discharge power of 1.0 kW while transporting the hard coat film in a vacuum atmosphere of 0.5 Pa.

<Formation of primer layer and antireflection layer>
The hard coat film after plasma treatment is introduced into a roll-to-roll type sputter film forming apparatus, the inside of the tank is depressurized to 1 × 10 ^-4 Pa, and then the film is run at a substrate temperature of -8 ° C to 4 nm. A SiO _x primer layer, a 16 nm Nb ₂ O ₅ layer, a 19 nm SiO ₂ layer, a 102 nm Nb ₂ O ₅ layer, and a 71 nm SiO ₂ layer were sequentially formed on the hard coat layer forming surface.

A Si target was used to form the SiO _x primer layer, and DC sputtering was performed under the conditions of a pressure of 0.2 Pa and a power density of 0.5 W / cm ² while introducing 3 parts by volume of oxygen with respect to 100 parts by volume of argon. The membrane was made.

A Si target is used to form the SiO ₂ layer (low refractive index layer), and an Nb target is used to form the Nb ₂ O ₅ layer (high refractive index layer), and the film is formed at an argon flow rate of 400 sccm and a pressure of 0.25 Pa. rice field. In the film formation of the SiO ₂ layer and the film formation of the Nb ₂ O ₅ layer, the amount of oxygen introduced so that the film formation mode maintains the transition region was adjusted by plasma emission monitoring (PEM) control.

[Anti-reflection film 1B-1F]
The amount of oxygen introduced during the formation of the SiO _x primer layer was changed as shown in Table 1. In the production of the antireflection film 1D, the power density was doubled and the film thickness of the SiO _x primer layer was set to 8 nm. Except for these changes, an antireflection film having an antireflection layer on the hard coat layer via a SiO _x primer layer was produced under the same conditions as the production of the antireflection film 1A.

[Anti-reflection film 2A]
Similar to the preparation of the antireflection film 1A, the hard coat film was prepared and the surface was treated with argon plasma. The hard-coated film after plasma treatment was introduced into a roll-to-roll spatter film forming apparatus, the inside of the tank was depressurized to 1 × 10 ^-4 Pa, and then the film was run at a substrate temperature of -8 ° C to 4 nm. An ITO primer layer, a 16 nm Nb ₂ O ₅ layer, a 19 nm SiO ₂ layer, a 102 nm Nb ₂ O ₅ layer, and a 71 nm SiO ₂ layer were formed in order on the hard coat layer forming surface.

To form the ITO primer layer, an oxide target containing indium oxide and tin oxide in a weight ratio of 90:10 was used, and while introducing 3 parts by volume of oxygen with respect to 100 parts by volume of argon, the pressure was 0.2 Pa. DC sputter film formation was performed under the condition of a power density of 0.5 W / cm ² . The SiO ₂ layer and the Nb ₂ O ₅ layer were formed under the same conditions as the antireflection film 1A.

[Anti-reflection film 2B-2H]
The amount of oxygen introduced during the formation of the ITO primer layer was changed as shown in Table 1, and the power density was further changed to form the ITO primer layer having the film thickness shown in Table 1. Except for these changes, an antireflection film having an antireflection layer on the hard coat layer via an ITO primer layer was produced under the same conditions as the production of the antireflection film 2A.

[Evaluation of antireflection film]
<Adhesion test (accelerated light resistance test)>
The surface of the antireflection film on the hard coat film side (antireflection layer non-forming surface) is bonded onto a glass plate via an acrylic transparent adhesive, and the temperature is 40 using the "ultraviolet fade meter U48" manufactured by Suga Testing Machine. An accelerated light resistance test was carried out for 500 hours under the conditions of ° C., humidity of 20%, and radiation intensity (300 to 700 nm integrated illuminance) of 500 ± 50 W / m ² .

The surface of the antireflection layer of the sample after the accelerated durability test was cut at 1 mm intervals to form a 100-square grid. Next, 2 mL of isopropyl alcohol was continuously dropped so that the surface of the antireflection layer did not dry, and a polyester wiper (“Anticon Gold” manufactured by Sampler Tech) fixed to a 20 mm square SUS jig was rubbed on the grid. It was moved (load: 1.5 kg, 1000 reciprocations). The number of grids in which the antireflection layer was peeled off in a region of 1/4 or more of the area of the mass was counted, and the adhesion was evaluated according to the following criteria.
S: The number of peeling grids is 0
A: The number of peeling go boards is 1 to 10 B: The number of peeling go boards is 11 to 50 C: The number of peeling go boards is 51 or more

<Transmittance>
The transmittance of the antireflection film is measured with an integrating sphere spectrophotometer (“DOT-3” manufactured by Murakami Color Technology Research Institute), and the transmittance (Y value, which is the visual transmittance of the XYZ color system of transmitted light). Asked.

For each of the antireflection films 1A to 1F having a SiO _x primer layer and the antireflection films 2A to 2H having an ITO primer layer, the amount of oxygen introduced during film formation of the primer layer (volume ratio to argon) and the thickness of the primer layer. , And the evaluation results of the transmittance and adhesion of the antireflection film are shown in Table 1.

The antireflection film 1C provided with the SiO _x primer layer had a high transmittance of 96.5% and excellent adhesion, but the antireflection film 1D having a larger primer layer had a lower transmittance. Was there. Further, even in the antireflection films 1A and 1B in which the amount of oxygen introduced during the film formation of the SiO _x primer layer was small, a decrease in the transmittance was observed. On the other hand, in the antireflection films 1E and 1F in which the amount of oxygen introduced during the formation of the primer layer was large, a decrease in adhesion was observed.

In the antireflection films 2A to 2H in which the ITO primer layer was formed using the oxide target, high transmittance and excellent adhesion were maintained even when the film thickness of the primer layer and the amount of oxygen introduced were changed.

In the silicon oxide primer layer, oxygen deficiency tended to decrease and the adhesion decreased as the amount of oxygen introduced during sputtering film formation increased, whereas in the ITO primer layer, the amount of oxygen introduced increased. As a result, the adhesion tended to improve, and both showed the opposite behavior with respect to the amount of oxygen introduced during film formation.

From these results, when the silicon oxide primer layer is formed using the Si target, a slight change in the spatter film formation conditions causes a decrease in the adhesion of the antireflection layer and a decrease in the transmittance of the antireflection film. On the other hand, by forming the ITO primer layer using the oxide target, the characteristics of the antireflection film do not change much even when the spatter film formation conditions change, the quality is stabilized, and high transparency is maintained. However, it can be seen that an antireflection film having excellent adhesion of the antireflection layer can be obtained.

1 Hardcoat film 10 Film substrate 11 Hardcoat layer 3 Primer layer 5 Antireflection layer 51,53 Low refractive index layer 52,54 High refractive index layer 100 Antireflection film

Claims (8)

A hard coat film having a hard coat layer on one main surface of a film substrate; a primer layer provided in contact with the hard coat layer; and an antireflection layer provided in contact with the primer layer. It ’s an anti-reflection film.
The hard coat layer is a cured resin layer obtained by curing a composition containing a curable resin.
The antireflection layer is a laminate of a plurality of thin films having different refractive indexes.
The primer layer is a metal oxide layer containing an oxide of one or more metals selected from the group consisting of In and Sn, and has a thickness of 0.5 to 8 nm.
Anti-reflective film. The antireflection film according to claim 1, wherein the primer layer is an indium-based oxide layer. The antireflection film according to claim 1, wherein the primer layer is an indium tin oxide layer. The antireflection film according to any one of claims 1 to 3, wherein the hard coat layer contains fine particles . The antireflection film according to any one of claims 1 to 4 , wherein the plurality of thin films constituting the antireflection layer are all inorganic oxide thin films. An image display device in which the antireflection film according to any one of claims 1 to 5 is arranged on a visible surface of an image display medium. The method for manufacturing an antireflection film according to any one of claims 1 to 5 .
A method for producing an antireflection film, in which a primer layer is formed on a hard coat layer by a sputtering method using an oxide target. The method for producing an antireflection film according to claim 7 , wherein an antireflection layer is formed on the primer layer by reactive sputtering.

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