KR102653072B1 - Anti-reflection film, method for producing same, and polarizing plate with anti-reflection layer - Google Patents

Abstract

The anti-reflection film 100 is provided with an anti-reflection layer 5 made of a plurality of thin films with different refractive indices on one main surface of the transparent film substrate 1. The anti-reflection layer includes a primer layer 50 in contact with the transparent film substrate. The primer layer has an argon content of 0.5 atomic% or less. The primer layer 50 is, for example, a silicon oxide layer. The moisture permeability of the anti-reflection film is preferably 1 g/m2·24 h or less. The polarizing plate 101 with the anti-reflection layer formed has the anti-reflection film 100 on the polarizer 8.

Description

Anti-reflection film and method of manufacturing the same, and polarizing plate with anti-reflection layer formed {ANTI-REFLECTION FILM, METHOD FOR PRODUCING SAME, AND POLARIZING PLATE WITH ANTI-REFLECTION LAYER}

The present invention relates to an anti-reflection film having an anti-reflection layer made of a plurality of thin films on a transparent film, and a method of manufacturing the same.

Anti-reflection films are used on the viewing surface of image display devices such as liquid crystal displays and organic EL displays for the purposes of preventing image quality from being degraded due to reflection of external light or overlapping images and improving contrast. The anti-reflection film includes an anti-reflection layer made of a laminate of a plurality of thin films with different refractive indices on a transparent film.

One form of the anti-reflection film includes a polarizing plate with an anti-reflection layer formed thereon. A polarizing plate with an anti-reflection layer formed is obtained by bonding an anti-reflection film to the surface of a polarizing plate or bonding an anti-reflection film as a protective film to the surface of a polarizer. An antireflection layer may be formed on the surface of the polarizing plate.

There are several known attempts to provide antireflection layers with water vapor barrier properties. For example, in Patent Document 1, water vapor barrier properties are improved by forming alternating laminated films of ITO and SiO ₂ by a sputtering method, and forming a silicon oxide film thereon by a plasma CVD method. In Patent Document 2, low moisture permeability of the anti-reflection film is attempted by forming a silicon nitride film with a high refractive index. Patent Document 3 describes that there is a high correlation between the density of the outermost layer of the antireflection layer (the layer furthest from the film substrate) and the moisture permeability.

Japanese Patent Publication No. 2000-338305 Japanese Patent Publication No. 2003-139907 Japanese Patent Publication No. 2009-109850

By forming an anti-reflection layer having water vapor barrier properties on the surface of the polarizing plate, deterioration of the polarizer in a high-humidity environment is suppressed and durability is improved. Recently, additional high-humidity durability has been required for displays, and anti-reflection films with higher water vapor barrier properties (low moisture permeability) than before have been required. In view of the above, the purpose of the present invention is to provide an antireflection film excellent in water vapor barrier properties.

The anti-reflection film of the present invention is provided with an anti-reflection layer made of a plurality of thin films with different refractive indices on one main surface of a transparent film substrate. The anti-reflection layer includes a primer layer in contact with the transparent film substrate. It is preferable that high refractive index layers and low refractive index layers are alternately laminated on the primer layer. The moisture permeability of the anti-reflection film is preferably 1 g/m2·24 h or less.

The argon content of the primer layer is preferably 0.01 to 0.5 atomic% or less. The primer layer is preferably a silicon oxide layer. The primer layer is preferably formed by a sputtering method. It is preferable that the thin film on the primer layer constituting the anti-reflection layer is also formed by a sputtering method.

Furthermore, the present invention relates to a polarizing plate in which an anti-reflection layer including the anti-reflection film is formed on one side of the polarizer.

The anti-reflection film of the present invention has excellent gas barrier properties, and even when a display having a polarizing plate on the surface of which an anti-reflection layer with low moisture permeability is formed is exposed to a high humidity environment, the amount of moisture entering the polarizer is small, thereby preventing deterioration of the polarizer. can be suppressed.

1 is a cross-sectional view schematically showing one form of an antireflection film.
Figure 2 is a cross-sectional view schematically showing one form of a polarizing plate with an anti-reflection layer formed thereon.

[Composition of anti-reflection film]

1 is a cross-sectional view schematically showing the structure of an anti-reflection film according to an embodiment. The anti-reflection film 100 is in contact with the transparent film base material 1 and is provided with an anti-reflection layer 5. The anti-reflection layer is a laminate of two or more thin films. The anti-reflection layer 5 shown in FIG. 1 has a primer layer 50 on the surface in contact with the transparent film base 1, and a high refractive index layer 51 thereon. , 53) and low refractive index layers (52, 54) are alternately stacked.

The moisture permeability of the antireflection layer 5 is preferably 1 g/m 2 ·24 h or less, more preferably 0.7 g/m 2 ·24 h or less, and still more preferably 0.5 g/m 2 ·24 h or less. By reducing the moisture permeability of the anti-reflection layer, the intrusion of moisture can be prevented, and deterioration of the polarizer and the like caused by moisture can be suppressed. As will be described in detail later, when the amount of argon contained in the primer layer is small, the moisture permeability of the antireflection film tends to decrease.

＜Transparent film substrate＞

The transparent film substrate 1 includes a flexible transparent film 10. It is preferable that the hard coat layer 11 is formed on the surface of the transparent film 10 on which the anti-reflection layer 5 is formed.

(transparent film)

The visible light transmittance of the transparent film 10 is preferably 80% or more, and more preferably 90% or more. The thickness of the transparent film 10 is not particularly limited, but is preferably about 5 to 300 μm, more preferably 10 to 250 μm, from the viewpoint of workability such as strength and handleability, and thinness, etc. ㎛ is more preferable.

Examples of the resin material constituting the transparent film 10 include thermoplastic resins excellent in transparency, mechanical strength, and thermal stability. Specific examples of such thermoplastic resins include cellulose-based resins such as triacetylcellulose, polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, Polyolefin-based resins, (meth)acrylic-based resins, cyclic polyolefin-based resins (norbornene-based resins), polyarylate-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof.

(hard coat layer)

By forming the hard coat layer 11 on the surface of the transparent film 10, mechanical properties such as hardness and elastic modulus of the anti-reflection film can be improved. The hard coat layer 11 preferably has high surface hardness and excellent scratch resistance. The hard coat layer 11 can be formed, for example, by applying a solution containing a curable resin onto the transparent film 10.

Examples of the curable resin include thermosetting resin, ultraviolet curing resin, and electron beam curing resin. Types of curable resins include various resins such as 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. These curable resins can be used alone or in combination of two or more, appropriately selected.

Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferable because they have high hardness, can be cured with ultraviolet rays, and are excellent in productivity, and among them, acrylic urethane resins are preferable. Ultraviolet curable resins include ultraviolet curable monomers, oligomers, polymers, etc. Preferably used ultraviolet curable resins include, for example, those having an ultraviolet polymerizable functional group, and those containing as a component an acrylic monomer or oligomer having two or more, particularly three to six, functional groups.

In order to provide anti-glare properties and anti-glare properties to the anti-reflection film, the hard coat layer 11 may have anti-glare properties. Examples of the anti-glare hard coat layer include those in which fine particles are dispersed in the curable resin matrix. Fine particles dispersed in the resin matrix include various metal oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide, glass fine particles, polymethyl methacrylate, polystyrene, and poly Transparent cross-linked or uncross-linked organic fine particles made of various transparent polymers such as urethane, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, silicone-based fine particles, etc. can be used without particular restrictions.

The hard coat layer 11 can be formed, for example, by applying a solution containing a curable resin onto the transparent film 10. It is preferable that an ultraviolet polymerization initiator is blended in the solution for forming the hard coat layer. In order to form an anti-glare hard coat layer containing fine particles, it is preferable to apply a solution containing the fine particles in addition to the curable resin onto a transparent film. The solution may contain additives such as leveling agents, thixotropic agents, and antistatic agents.

The thickness of the hard coat layer 11 is not particularly limited, but in order to realize high hardness, it is preferably 0.5 μm or more, and more preferably 1 μm or more. Considering the ease of formation by application, the thickness of the hard coat layer is preferably 15 μm or less, and more preferably 10 μm or less.

The arithmetic mean roughness (Ra) of the surface of the transparent film substrate 1 on the side where the anti-reflection layer 5 is formed is preferably 1.0 nm or less. When the hard coat layer 11 is formed on the transparent film 10, the arithmetic mean roughness (Ra) of the hard coat layer 11 is the surface of the transparent film 10 on the side where the anti-reflection layer 5 is formed. becomes the arithmetic average illuminance of The arithmetic mean roughness (Ra) is obtained from an observation image of 1 μm square using an atomic force microscope (AFM).

As described above, when the hard coat layer 11 is formed by application, the arithmetic mean roughness of the surface of the transparent film base material 1 can be reduced. If the surface of the transparent film substrate 1 is smooth, defects such as pinholes in the anti-reflection layer 5 can be suppressed, and an anti-reflection film with lower moisture permeability can be obtained.

(Surface treatment)

The surface of the transparent film substrate 1 is treated with corona treatment, plasma treatment, frame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, and coupling agent for the purpose of improving adhesion with the anti-reflection layer 5, etc. Surface modification treatment such as may be performed.

＜Anti-reflective layer＞

An anti-reflection film is formed by forming an anti-reflection layer (5) on a transparent film substrate (1). The anti-reflection layer 5 is provided with a primer layer 50 on the surface in contact with the transparent film base material 1, and is provided with a high refractive index layer and a low refractive index layer thereon. In general, the optical thickness of the anti-reflection layer (the product of the refractive index and the thickness) of the thin film is adjusted so that the reversed phases of incident light and reflected light cancel each other. By making the anti-reflection layer a multilayer laminate of a plurality of thin films with different refractive indices, the reflectance can be reduced in the wide wavelength range of visible light.

Materials for the thin film constituting the antireflection layer 5 include metal oxides, nitrides, and fluorides. As a material for the primer layer 50, silicon oxide is preferable. The primer layer 50 has an argon content of 0.5 atomic% or less. The low refractive index layers 52 and 54 have, for example, a refractive index of 1.6 or less, preferably 1.5 or less. Low refractive index materials include silicon oxide, magnesium fluoride, and the like. 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 high refractive index materials include titanium oxide, niobium oxide, zirconium oxide, indium tin oxide (ITO), and antimony doped tin oxide (ATO). In addition to the low refractive index layer and the high refractive index layer, a thin film made of, for example, titanium oxide or a mixture of the low refractive index material and the high refractive index material may be formed as a medium refractive index layer with a refractive index of about 1.6 to 1.9.

The method of forming the thin film constituting the anti-reflection layer 5 is not particularly limited, and may be either a wet coating method or a dry coating method. Since it is possible to form a thin film with a uniform film thickness, dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam deposition are preferable. Among them, the sputtering method is preferable because it has excellent film thickness uniformity and is easy to form a dense film with high gas barrier properties. In particular, in order to obtain an anti-reflection film with low moisture permeability, it is preferable to form silicon oxide as the primer layer 50 by a sputtering method.

In the sputtering method, since a plurality of thin films can be formed continuously while conveying a long film substrate in one direction (longitudinal direction) using a roll-to-roll method, the productivity of the anti-reflection film can be improved. In order to improve the productivity of the anti-reflection film, it is preferable to form all thin films constituting the anti-reflection layer 5 by a sputtering method. In the sputtering method, film formation is performed while introducing an inert gas such as argon and, if necessary, a reactive gas such as oxygen into the chamber.

The formation of an oxide layer by a sputtering method can be performed by either a method using an oxide target or a reactive sputtering method using a metal target. In order to form an insulating oxide such as silicon oxide using an oxide target, RF discharge is required. To deposit metal oxides at high rates, reactive DC sputtering using a metal target is preferred.

(Primer layer)

The amount of argon in the primer layer 50 is 0.5 atomic% or less, and preferably 0.4 atomic% or less. When the amount of argon in the sputtered film is 0.5 atomic% or less, the moisture permeability is reduced and the water vapor barrier property of the antireflection film tends to improve. It is not clear why the anti-reflection layer has low moisture permeability due to a reduction in the amount of argon in the primer layer, but one factor is that if argon with a large atomic radius is present in the primer layer, water vapor is formed in the primer layer and the thin film formed on it. It is thought that this is related to the ease with which gas paths such as these are easily formed.

As described above, in sputter deposition, argon is used as a process gas, high-energy argon collides with the target to bounce the material from the target, and the sputter particles bounced from the target are deposited on the substrate, The tabernacle is carried out. Inert gases such as argon are generally not involved in film formation, but since ionized argon is highly reactive, a portion of argon as a process gas is inevitably introduced into the film during sputter film formation.

Since argon, a noble gas, has a larger atomic diameter than silicon or oxygen, argon introduced into the film may inhibit the formation of the Si-O bond network of silicon oxide and cause the formation of atomic-level voids. When voids resulting from the incorporation of argon are formed in the primer layer 50, which is first formed in contact with the film substrate 1, the high refractive index layers 51, 53 or the low refractive index layers 52, 54 are sputtered thereon. At this time, the voids tend to grow columnar in the thickness direction, and this becomes a passage for gases such as water vapor, and it is thought that the moisture permeability increases. In contrast, it is believed that by reducing the amount of argon introduced into the primer layer 50, the creation of voids through which water vapor passes is suppressed, and a low moisture permeable anti-reflection layer with excellent water vapor barrier properties is formed.

The smaller the amount of argon contained in the primer layer 50, the more desirable it is, but the film obtained by sputter film formation using argon as the process gas usually contains 0.01 atomic% or more of argon. The argon content in the primer layer may be 0.05 atomic% or more, or 0.1 atomic% or more. The amount of argon in the film is measured by the Rutherford backscattering (RBS) method, and the amount of argon in the silicon oxide film is a calculated value with the total content of silicon, oxygen, and argon set to 100 atomic%.

As a method of suppressing the mixing of argon into the primer layer, it is desirable to increase the mean free stroke and promote scattering of argon by reducing the process pressure during film formation. The process pressure at the time of forming the primer layer 50 is preferably about 0.05 to 2 Pa, more preferably about 0.07 to 1 Pa, more preferably 0.1 to 0.5 Pa, and especially preferably 0.1 to 0.3 Pa. The amount of oxygen introduced into the deposition chamber when forming the primer layer 50 is preferably about 0.1 to 10%, more preferably about 0.5 to 5%, and still more preferably about 1 to 3% of the argon introduction amount in terms of volume ratio. .

By introducing oxygen in addition to argon during sputter film formation to promote the formation of a Si-O bond network, the incorporation of argon into the film tends to be suppressed. On the other hand, in order to improve the adhesion between the film substrate 1 and the anti-reflection layer 5, it is preferable that the oxygen content of the primer layer 50 is less than the stoichiometric composition. The film thickness of the primer layer 50 is sufficient as long as it does not impair the transparency of the transparent film base material 1, and is, for example, about 1 to 10 nm.

(Thin film on primer layer)

The type of thin film formed on the primer layer 50 is not particularly limited. From the viewpoint of reducing reflectance over a wide wavelength range, it is preferable to alternately form high refractive index layers and low refractive index layers. In order to reduce reflection at the air interface, the thin film 54 formed as the outermost layer (the layer furthest from the film substrate 1) of the antireflection layer 5 is preferably a low refractive index layer. As the material for the low refractive index layer and the high refractive index layer, oxide is preferable as described above. Among these, it is preferable to alternately laminate niobium oxide (Nb ₂ O ₅ ) thin films 51 and 53 as high refractive index layers and silicon oxide (SiO ₂ ) thin films 52 and 54 as low refractive index layers.

In the sputter deposition of the low refractive index layer and the high refractive index layer on the primer layer, it is desirable to control the amount of oxygen introduced so that the deposition mode is in the transition region. For example, in the plasma emission monitoring method (PEM method), which detects the intensity of plasma emission of discharge and controls the amount of gas introduced into the film deposition chamber, feedback on the amount of oxygen introduced is provided based on the intensity of plasma emission. By controlling the amount of oxygen introduced by PEM, when forming a thin film by a roll-to-roll method, the film forming rate can be kept constant, so the film thickness of the thin film becomes uniform, and an anti-reflection film with excellent anti-reflection characteristics is obtained. . By forming a plurality of plasma emission measurement points in the width direction and independently controlling the amount of oxygen introduced by PEM, the uniformity of quality in the width direction can also be improved.

＜Additional layer on anti-reflection layer＞

The anti-reflection film may have an additional functional layer formed on the surface of the anti-reflection layer 5. Because the anti-reflection film is disposed on the outermost surface of the display, it is susceptible to contamination from the external environment (fingerprints, hand stains, dust, etc.). In particular, the low refractive index layer 54 such as SiO ₂ formed on the outermost surface of the anti-reflection layer 5 has good wettability, and contaminants such as fingerprints and hand stains easily adhere to it. For the purpose of preventing contamination from the external environment or facilitating removal of attached contaminants, an anti-fouling layer (not shown) may be formed on the anti-reflection layer.

The antifouling layer preferably has a small refractive index difference with the low refractive index layer 54 on the outermost surface of the antireflection layer 5. The refractive index of the antifouling layer is preferably 1.6 or less, and more preferably 1.55 or less. As a material for the antifouling layer, a silane-based compound containing a fluorine group or an organic compound containing a fluorine group is preferable. The antifouling layer can be formed by a wet method such as a reverse coat method, a die coat method, or a gravure coat method, or a dry method such as a CVD method. 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.

[Polarizer with anti-reflection layer]

Anti-reflective films are used, for example, by placing them on the surface of a display. As shown in FIG. 2, a polarizing plate with an anti-reflection layer formed by laminating an anti-reflection film 100 with a polarizer 8 may be bonded to the surface of the display. In the polarizing plate 101 with an anti-reflection layer shown in FIG. 2, one side of the polarizer 8 is bonded to the main surface of the transparent film substrate 1 opposite to the surface on which the anti-reflection layer 5 is formed. A transparent film (9) is bonded to the other side of the polarizer (8). In this configuration, the film substrate 1 has both a function as a substrate for forming the anti-reflection layer 5 and a function as a protective film for the polarizer 8. In the production of the anti-reflection film, the polarizer 8 and the film substrate 1 may be bonded together to produce a polarizing plate, and the anti-reflection layer 5 may be formed on the film substrate 1 of the polarizing plate.

As the polarizer (8), a dichroic substance such as iodine or a dichroic dye is adsorbed onto a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film. Examples include polyene-based oriented films such as uniaxially stretched products, dehydrated products of polyvinyl alcohol, and dehydrochlorinated products of polyvinyl chloride.

Among them, because it has a high degree of polarization, polyvinyl alcohol is oriented in a predetermined direction by adsorbing a dichroic substance such as iodine or dichroic dye to a polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol. Alcohol (PVA) based polarizers are preferred. For example, a PVA-based polarizer is obtained by subjecting a polyvinyl alcohol-based film to iodine dyeing and stretching. As the PVA-based polarizer, a thin polarizer with a thickness of 10 μm or less can also be used. As a thin polarizer, it is described, for example, in Japanese Patent Application Laid-Open No. 51-069644, Japanese Patent Application Publication No. 2000-338329, WO2010/100917 pamphlet, Japanese Patent No. 4691205 specification, Japanese Patent No. 4751481 specification, etc. A thin polarizing film can be mentioned. Such a thin polarizer is obtained, for example, by a manufacturing method including a step of stretching a PVA-based resin layer and a resin substrate for stretching in the state of a laminated body, and a step of iodine dyeing.

As the transparent film 9, the same materials as those described above as the material for the transparent film 10 are preferably used. In addition, the material of the transparent film 9 and the material of the transparent film 10 may be the same or different.

It is preferable to use an adhesive to bond the polarizer and the transparent film. Adhesives include acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl alcohol, polyvinyl ether, vinyl acetate/vinyl chloride copolymer, modified polyolefin, epoxy polymer, fluorine polymer, rubber polymer, etc. A polymer can be appropriately selected and used. A polyvinyl alcohol-based adhesive is preferably used to adhere the PVA-based polarizer.

The anti-reflection film of the present invention and the polarizing plate provided with the anti-reflection layer are used in displays such as liquid crystal displays and organic EL displays. In particular, when used as the outermost surface layer of a display, it contributes to improving the visibility of the display by preventing reflection. By forming the low-moisture-permeable anti-reflection film 100 provided with a predetermined primer layer 50 on the surface of the polarizer 8, the intrusion of moisture into the polarizer 8 from the external environment can be suppressed. Therefore, even when the display is exposed to a high-humidity environment, yellowing or discoloration due to deterioration of the polarizer is unlikely to occur, and changes in display characteristics can be suppressed.

Example

Below, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Production of film with hard coat layer]

100 parts by weight (solid content) of ultraviolet curable acrylic resin (manufactured by DIC, brand name "GRANDIC PC-1070", refractive index: 1.52) and 50 parts by weight of nano silica particles as an inorganic filler were mixed to prepare a composition for forming a hard coat layer. This composition was applied to one side of a 100 µm thick cellulose triacetate film (Fuji Film Co., Ltd., brand name “Fujitak”) so that the thickness after drying was 5 µm, and dried at 80°C for 3 minutes. After that, using a high-pressure mercury lamp, ultraviolet rays with an accumulated light amount of 200 mJ/cm 2 were irradiated to cure the application layer to form a hard coat layer.

[Example 1]

The triacetylcellulose film on which the hard coat layer was formed was introduced into a roll-to-roll type sputter film deposition apparatus, and while the film was running, bombard treatment (plasma treatment with Ar gas) was applied to the surface on which the anti-glare hard coat layer was formed. As a primer layer, a 3.5 nm silicon oxide layer was formed, and on it, a 12 nm Nb ₂ O ₅ layer, a 28 nm SiO ₂ layer, a 100 nm Nb ₂ O ₅ layer, and an 85 nm SiO ₂ layer were formed. An anti-reflection film was produced by forming a film in order.

Bombard treatment was performed at a pressure of 1.5 Pa. The silicon oxide layer as the primer layer had a substrate temperature of -8°C, an argon flow rate of 300 sccm, an oxygen flow rate of 4.5 sccm, and a pressure of 0.2 Pa, and DC sputter film formation was performed by applying a power of 0.5 W/cm2 to the Si target. A Si target was used to form the SiO ₂ layer, and an Nb target was used to form the Nb ₂ O ₅ layer, and film formation was performed at a substrate temperature of -8°C, an argon flow rate of 400 sccm, and a pressure of 0.25 Pa. In the formation of the SiO ₂ layer and the Nb ₂ O ₅ layer, the amount of oxygen introduced was adjusted to maintain the film formation mode in the transition region through plasma emission monitoring (PEM) control.

[Example 2 and Comparative Example 1]

The sputter film formation conditions of the primer layer were changed as shown in Table 1, and in Comparative Example 1, the primer layer was formed without introducing oxygen. Additionally, in Comparative Example 1, the argon flow rate was changed to 1200 sccm and the pressure was changed to 0.45 Pa. Other than that, an antireflection film was produced in the same manner as in Example 1.

[Evaluation of anti-reflective film]

(Water permeability)

In accordance with JIS K 7129:2008 Annex B, the moisture permeability of the anti-reflection film was measured in an atmosphere of 40°C temperature and 90% RH humidity. Since the moisture permeability of the film base material was sufficiently large compared to the moisture permeability of the anti-reflection layer, the moisture permeability of the entire anti-reflection film was considered to be equal to the moisture permeability of the anti-reflection layer.

(Film density and composition of thin films)

The film density and composition of the thin film constituting the anti-reflection layer were measured by the Rutherford backscattering (RBS) method. In calculating the film density, the film thickness obtained from cross-sectional transmission electron microscope (TEM) observation was used. The elemental composition was calculated based on the elemental composition at the center of the film thickness of each thin film, with the total content of metal (silicon or niobium), oxygen, and argon set to 100 atomic%.

[Manufacture and durability evaluation of polarizer with anti-reflection layer]

The anti-reflection films of Examples and Comparative Examples were bonded to one side of the polarizer, and a transparent film with a thickness of 30 μm made of a modified acrylic polymer having a lactone ring structure was bonded to the other side of the polarizer to form an anti-reflection layer. A polarizer was manufactured. As the polarizer, a PVA-based polarizer was used, which was a polyvinyl alcohol film with an average degree of polymerization of 2700 and a thickness of 75 μm, stretched six times while dyed with iodine. For adhesion of a PVA-based polarizer and a transparent film, an aqueous solution containing acetoacetyl group-containing polyvinyl alcohol resin (average degree of polymerization 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine at a weight ratio of 3:1 An adhesive consisting of was used, and after bonding together with a roll bonding machine, it was heated and dried in an oven.

The obtained polarizing plate with the anti-reflection layer formed was put into a constant temperature and humidity tank at 60°C and 90%RH, and taken out after 72 hours. A commercially available polarizing plate was placed on the backlight, and the amount of change Δb ^* in the chromaticity b ^* of transmitted light before and after the heating and humidification test was determined.

Table 1 shows the film properties of each layer of the anti-reflection layer of the examples and comparative examples, the film formation conditions of the primer layer, the moisture permeability of the anti-reflection film, and the amount of change in transmitted light b ^* before and after the heating and humidification test of the polarizing plate with the anti-reflection layer formed.

As shown in Table 1, the anti-reflection films of Examples 1 and 2 had lower moisture permeability than Comparative Example 1, the chromaticity difference before and after the heating and humidification test of the polarizing plate with the anti-reflection layer formed was small, and exhibited good durability. There was no clear difference in the film density of the outermost SiO ₂ layer (film thickness: 85 nm) between the examples and comparative examples.

Since Nb ₂ O ₅ has a higher moisture permeability than SiO ₂ , in the alternating laminate film of SiO ₂ and Nb ₂ O ₅ , moisture permeation of the SiO ₂ film is the rate limiting factor, and the moisture permeability mainly depends on the characteristics of the SiO ₂ film. In Comparative Example 1, since the film formation pressure of the Nb ₂ O ₅ layer was low, the film density of the Nb ₂ O ₅ layer tended to be smaller compared to Examples 1 and 2, but the difference in film density of the Nb ₂ O ₅ layer was It is thought that it has little effect on the change in moisture permeability.

In Examples 1 and 2 and Comparative Example 1, the film formation conditions for the primer layer are different, and in Examples 1 and 2, where film formation was performed at a low argon introduction amount (low pressure) while introducing oxygen, the amount of argon in the film was lower than in Comparative Example 1. It was changing. From these results, it is thought that in the Examples, the amount of argon contained in the primer layer was reduced, thereby improving the water vapor barrier property of the anti-reflection film (reducing the moisture permeability) and improving the durability of the polarizing plate on which the anti-reflection layer was formed.

1: Transparent film base
10: Transparent film
11: Hard coat layer
5: Anti-reflection layer
50: primer layer
51, 52, 53, 54: thin film
8: Polarizer
9: Transparent film
100: anti-reflection film
101: Polarizer with anti-reflection layer formed

Claims (8)

An anti-reflection film comprising an anti-reflection layer made of a plurality of thin films with different refractive indices on one main surface of a transparent film base, comprising:
The antireflection layer includes a primer layer in contact with the transparent film substrate,
The primer layer is a silicon oxide layer, and the antireflection film has an argon content of 0.01 to 0.5 atomic%. According to claim 1,
The anti-reflection layer is an anti-reflection film comprising alternating high refractive index layers and low refractive index layers on the primer layer. According to claim 2,
An antireflection film wherein the high refractive index layer is a niobium oxide layer, the low refractive index layer is a silicon oxide layer, and the oxygen amount of the silicon oxide of the primer layer is less than the oxygen amount of the silicon oxide of the low refractive index layer. According to claim 1,
An anti-reflective film with a moisture permeability of 1 g/㎡·24 h or less. According to claim 1,
An anti-reflection film wherein the transparent film substrate has a hard coat layer on a surface in contact with the primer layer. A polarizing plate with an antireflection layer provided on one side of the polarizer with the antireflection film according to any one of claims 1 to 5. A method for producing the antireflection film according to any one of claims 1 to 5, comprising:
A method for producing an antireflection film, wherein the primer layer is formed by a sputtering method. According to claim 7,
A method of producing an anti-reflection film, wherein all thin films constituting the anti-reflection layer are formed by a sputtering method.