JP2022065438A - Polarizing plate with antireflection layer and image display unit - Google Patents

Abstract

To provide a polarizing plate with an antireflection layer in which a polarizer is hardly deteriorated even when exposed to a high temperature and high humidity environment.SOLUTION: In a polarizing plate with an antireflection layer (200), a polarizing plate (101) and an antireflection film (105) are laminated to each other with an adhesive layer (8) therebetween. In the polarizing plate, a first transparent protective film (2) is laminated on a first principal surface of a polarizer (1), and a steam barrier layer (3) is provided thereon. The moisture permeability of the steam barrier layer is 1 g/m2 24h or less. The hygroscopic expansion rate of the first transparent protective film is preferably 0.10% or less, and the arithmetic average height Sa of a first principal surface of the first transparent protective film is preferably 1.5 nm or less. The antireflection film includes an antireflection layer (5) on a first principal surface of a transparent film substrate (4).SELECTED DRAWING: Figure 1

Description

The present invention relates to a polarizing plate with an antireflection layer having an antireflection layer on the surface of the polarizing plate, and an image display device.

Liquid crystal displays and organic EL display devices are widely used as various image display devices such as mobile phones, car navigation devices, personal computer monitors, and televisions. Due to the display principle of the liquid crystal display device, a polarizing plate is arranged on the visible surface of the image display cell. Further, in the organic EL display device, in order to prevent external light from being reflected by the metal electrode (cathode) and visually recognized like a mirror surface, a circular polarizing plate (polarizing plate and 1) is formed on the visible side surface of the image display cell. (A laminate of 4 wave plates) may be arranged.

The polarizing plate generally includes a transparent film on one side or both sides of the polarizing element for the purpose of protecting the polarizing element. As the polarizing element, one in which iodine is adsorbed on a polyvinyl alcohol (PVA) -based film and the molecules are oriented by stretching or the like is widely used.

When the polarizing plate is exposed to a high-temperature and high-humidity environment, the stator deteriorates due to moisture, resulting in a change in hue and a decrease in the degree of polarization. In order to prevent deterioration of the polarizing element, it has been proposed to provide a thin film having a water vapor barrier property on the surface of the polarizing plate. For example, Patent Document 1 discloses an optical laminate in which a gas barrier film is bonded to the surface of a polarizing plate via an adhesive layer. Patent Document 2 provides a water vapor barrier property by forming an antireflection layer on a transparent film provided on the surface of a polarizing element.

Japanese Unexamined Patent Publication No. 2017-134370 Japanese Unexamined Patent Publication No. 2010-231160

As disclosed in Patent Document 2, when an antireflection layer having a function as a water vapor barrier layer is provided on the surface of the polarizing plate, the antireflection layer is configured in order to exhibit the function as the antireflection layer. Since the design of the thin film material and film thickness is limited, it may be difficult to provide sufficient water vapor barrier properties. Further, since the antireflection layer is arranged on the outermost surface of the image display device, scratches are likely to occur in the usage environment of the image display device. Even if the antireflection layer has an excellent water vapor barrier property, if the antireflection layer is scratched, moisture easily infiltrates into the inside of the polarizing plate from that portion, and when exposed to a high temperature and high humidity environment, it is polarized. Display unevenness may occur due to local deterioration of the child.

In view of the above, it is an object of the present invention to provide a polarizing plate with an antireflection layer, which has excellent durability and is less likely to cause deterioration of the polarizing element even when exposed to a high temperature and high humidity environment.

The polarizing plate with an antireflection layer includes a polarizing plate, an antireflection film, and an adhesive layer. The polarizing plate includes a polarizing element and a first transparent protective film bonded to the first main surface of the polarizing element, and a water vapor barrier layer is provided on the first main surface of the first transparent protective film. A second transparent protective film may be attached to the second main surface of the splitter. The antireflection film includes an antireflection layer on the first main surface of the transparent film base material. In the polarizing plate with an antireflection layer, the water vapor barrier layer of the polarizing plate and the transparent film base material of the antireflection film are bonded to each other via an adhesive layer.

The coefficient of thermal expansion of the first transparent protective film of the polarizing plate is preferably 0.10% or less. The arithmetic average height Sa of the first main surface (water vapor barrier layer forming surface) of the first transparent protective film is preferably 1.5 nm or less. The first transparent protective film may be provided with a smoothing coating layer on the first main surface of the transparent film.

The water vapor barrier layer has a moisture permeability of ¹ g / m 2.24 h or less, and preferably 0.5 g / ^m 2.24 h or less. As the material of the water vapor barrier layer, a ceramic material made of an oxide of a metal or a metalloid element such as Si, Al, In, Sn, Zn, Ti, Nb, Ce, Zr, a nitride or an oxynitride is preferable. The water vapor barrier layer is preferably a sputtered film formed by a sputtering method.

The transparent film base material of the antireflection film may have a hard coat layer on the surface of the transparent film. The antireflection film may include a primer layer between the transparent film base material and the antireflection layer. The antireflection layer is preferably a laminate of a plurality of thin films having different refractive indexes. The thin film constituting the antireflection layer is a sputtered film formed by a sputtering method. An antifouling layer may be provided on the antireflection layer.

The interfacial reflectance between the water vapor barrier layer and the pressure-sensitive adhesive layer is preferably 1% or less. For example, the interfacial reflectance can be reduced by adjusting the material and thickness of the water vapor barrier layer.

The polarizing plate with an antireflection layer of the present invention has excellent durability, and even when exposed to a high-temperature and high-humidity environment, deterioration due to the infiltration of water into the polarizing element is unlikely to occur. Further, even if the antireflection layer is scratched, the infiltration of water into the polarizing element is suppressed, so that even in the usage environment of the image display device, the display characteristics are deteriorated and the display unevenness is caused due to the deterioration of the polarizing element. It is hard to occur and has excellent durability.

It is sectional drawing which shows the laminated form of the polarizing plate with an antireflection layer. It is sectional drawing which shows the laminated form of the image display apparatus which provided the polarizing plate with the antireflection layer on the surface of the image display medium on the visual recognition side.

FIG. 1 is a cross-sectional view showing a laminated configuration example of a polarizing plate with an antireflection layer, and FIG. 2 is a cross section showing a laminated configuration example of an image display device provided with a polarizing plate 200 with an antireflection layer on an image display medium 110. It is a figure. In the polarizing plate 200 with an antireflection layer, an antireflection film 105 is bonded to the first main surface of the polarizing plate 101 via an adhesive layer 8. In the following, the main surface on the upper side (antireflection film 105 side) of each layer will be referred to as “first main surface”, and the main surface on the lower side (polarizing plate 101 side) will be referred to as “second main surface”.

The polarizing plate 101 has a first transparent protective film 2 bonded to the first main surface of the polarizing element 1, and a water vapor barrier layer 3 is provided on the first main surface of the first transparent protective film 2. A second transparent protective film 15 may be attached to the second main surface of the polarizing element 1. An adhesive layer 9 for bonding to the image display medium 110 may be laminated on the second main surface of the polarizing plate 101.

The antireflection film 105 includes an antireflection layer 5 on the first main surface of the transparent film base material 4. A primer layer 50 may be provided between the transparent film base material 4 and the antireflection layer 5. An antifouling layer 6 may be provided on the first main surface of the antireflection layer 5.

[Polarizer with water vapor barrier layer]
<Polarizer>
The polarizing element 1 includes 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 property such as iodine or a dichroic dye. Examples thereof include a uniaxially stretched film by adsorbing a substance, a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrogenated product of polyvinyl chloride.

Above all, since it has a high degree of polarization, it is oriented in a predetermined direction by adsorbing a dichroic substance such as iodine or a dichroic dye on a polyvinyl alcohol (PVA) -based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol. PVA-based polarizing elements that have been made to be used are preferable. For example, a PVA-based polarizing element can be obtained by subjecting a PVA-based film to iodine dyeing and stretching.

The thickness of the splitter is, for example, about 2 to 50 μm. A thin polarizing element can also be used as the polarizing element. For example, a thin PVA-based polarizing element can be obtained by a production method including a step of stretching a PVA-based resin layer and a stretching resin base material in a laminated state and a step of iodine dyeing. The thickness of the splitter may be 20 μm or less, 15 μm or less, 10 μm or less, or 8 μm or less.

<Transparent protective film>
A transparent protective film 2 is attached to the first main surface of the polarizing element 1 via an adhesive layer (not shown). The visible light transmittance of the transparent protective film 2 is preferably 80% or more, more preferably 90% or more. The transparent protective film 2 may include a coating layer 22 on the transparent film 21.

The transparent protective film 2 arranged on the first main surface of the polarizing element 1 has a function as a polarizing element protective film and a function as a base layer of the water vapor barrier layer 3. The transparent protective film 2 preferably has a small coefficient of moisture absorption and expansion. The moisture absorption expansion coefficient is the dimensional change rate of the film after being allowed to stand in an environment with a temperature of 65 ° C. and a relative humidity of 90% for 72 hours.

Due to the small hygroscopic expansion rate of the transparent protective film 2, even when the polarizing plate is exposed to a high temperature and high humidity environment, cracks are unlikely to occur in the barrier layer 3, and deterioration of the polarizing element 1 due to moisture (mainly yellowing). ) Tends to be suppressed. The moisture absorption expansion coefficient of the transparent protective film 2 is preferably 0.10% or less, more preferably 0.08% or less. The moisture absorption expansion rate may be 0.06% or less or 0.05% or less. The moisture absorption expansion coefficient of the transparent protective film 2 may be a negative value (the size becomes smaller due to moisture absorption). When the coefficient of thermal expansion is excessively small (the coefficient of contraction is large), poor appearance such as color unevenness due to the stress at the interface with the polarizing element is likely to occur. Therefore, the moisture absorption expansion coefficient of the transparent protective film is preferably −0.20% or more, more preferably −0.15% or more, still more preferably −0.10% or more.

The transparent protective film 2 may have anisotropy of the coefficient of moisture absorption and expansion. For example, a film produced by a roll-to-roll process may have anisotropy in the transport direction (MD) and the width direction (TD). Further, the stretched film may have anisotropy in the stretching direction and the direction orthogonal to the stretching direction. When the transparent protective film 2 has an anisotropic expansion coefficient of moisture absorption, the expansion coefficient of moisture absorption in any one direction may be within the above range. It is preferable that both the moisture absorption expansion rate of MD and TD are in the above range.

The transparent film 21 is preferably one having excellent transparency and heat resistance and having a small hygroscopic expansion rate. Generally, the smaller the water absorption rate, the smaller the moisture absorption expansion rate tends to be. Examples of the resin material constituting the transparent film 21 include (meth) acrylic resins, polyesters such as polyethylene terephthalate (PET), polyolefins, cyclic polyolefins (polynorbornene), polycarbonates, polyethersulfones, polysulfones, and polystyrenes. .. As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure or a (meth) acrylic resin having an unsaturated carboxylic acid alkyl ester unit and a glutarimide unit may be used.

The thickness of the transparent protective film 2 is not particularly limited, but is preferably about 5 to 300 μm, more preferably 10 to 300 μm, and even more preferably 20 to 200 μm from the viewpoint of workability such as strength and handleability, and thin layer property. When the transparent protective film 2 includes the coating layer 22 on the surface of the transparent film 21, it is preferable that the thickness including the coating layer 22 is within the above range.

The first main surface (barrier layer 3 forming surface) of the transparent protective film 2 preferably has few surface irregularities and is smooth. If the first main surface of the transparent protective film 2 is smooth, the water vapor barrier property of the water vapor barrier layer 3 formed on the transparent protective film 2 tends to be enhanced, and the moisture permeability tends to be reduced. The arithmetic average height Sa of the first main surface of the transparent protective film 2 is preferably 1.5 nm or less, more preferably 1.2 nm or less, still more preferably 1.0 nm or less. The arithmetic mean height Sa may be 0.8 nm or less, 0.6 nm or less, or 0.5 nm or less. The arithmetic mean height Sa is calculated according to ISO 25178 from the three-dimensional surface shape in the range of 1 μm × 1 μm measured by an atomic force microscope (AFM).

By providing the coating layer 22 having a smoothing action on the surface of the transparent film 21, the arithmetic average height Sa of the transparent protective film 2 can be reduced. The coating layer 22 for smoothing the surface is preferably formed by wet coating. Since the surface unevenness of the transparent film 21 is alleviated by the wet coating, the arithmetic mean height Sa tends to be small.

The thickness of the coating layer 22 is not particularly limited. The thicker the coating layer, the higher the smoothness of the surface. The thickness of the coating layer 22 provided for smoothing the surface is preferably 0.5 μm or more, more preferably 1 μm or more. The thickness of the coating layer 22 may be 10 μm or less, 7 μm or less, or 5 μm or less.

The coating layer 22 may be a hard coat layer (cured resin layer). In the polarizing plate with an antireflection layer, the water vapor barrier layer 3 provided on the coating layer 22 is attached to the pressure-sensitive adhesive layer 8 and is not exposed on the surface, so that it is not necessary to increase the hardness in particular. Therefore, the coating layer 22 does not necessarily have to be a hard coat layer, and may be a coating layer of a resin solution having no curability. Further, if the transparent film 21 has high smoothness, the coating layer 22 may not be provided.

A second transparent protective film 15 may be attached to the second main surface of the polarizing element 1. The thickness and material of the second transparent protective film 15 are not particularly limited, and the thickness and material of the first transparent protective film 2 may be the same as those described above. The material of the second transparent protective film 15 may be the same as that of the first transparent protective film. The second transparent protective film 15 is not required to have smoothness and low hygroscopic expansion like the first transparent protective film 2 which is the base of the barrier layer 3. Therefore, as the material of the second transparent protective film, a material having high water absorption such as a cellulosic material may be used.

The second transparent protective film 15 may also have a function as a retardation plate. The second transparent protective film 15 may be a laminated film having two or more layers, or may be a laminated retardation plate. The second transparent protective film may be a transparent film provided with a birefringent layer such as an oriented liquid crystal layer.

It is preferable to use an adhesive for bonding the polarizing element 1 and the transparent protective films 2 and 15. Examples of the adhesive material include epoxy resin, silicone resin, acrylic resin, polyurethane, polyamide, polyether, polyvinyl alcohol and the like. The thickness of the adhesive layer is, for example, about 0.01 to 10 μm. When a curable adhesive that exhibits adhesiveness by a cross-linking reaction is used, the thickness of the adhesive layer is preferably 0.01 to 5 μm, more preferably 0.03 to 3 μm.

As the adhesive, various forms such as a water-based adhesive, a solvent-based adhesive, a hot-melt adhesive-based adhesive, and an active energy ray-curable adhesive are used. Among these, a water-based adhesive or an active energy ray-curable adhesive is preferable because the thickness of the adhesive layer can be reduced. Examples of the polymer component of the water-based adhesive include vinyl polymers, gelatins, vinyl-based latexs, polyurethanes, polyesters, and epoxies. The active energy ray-curable adhesive is an adhesive capable of radical polymerization, cationic polymerization or anionic polymerization by irradiation with active energy rays such as electron beam and ultraviolet rays. Among them, a photoradical polymerizable adhesive, a photocationic polymerizable adhesive, or a hybrid type adhesive in which photocationic polymerization and photoradical polymerization are used in combination are preferable because they can be cured with low energy. .. Examples of the monomer of the radically polymerizable adhesive include a compound having a (meth) acryloyl group and a compound having a vinyl group.

<Water vapor barrier layer>
A water vapor barrier layer 3 having a moisture permeability of 1 g / ^m and 2.24 h or less is provided on the first main surface of the transparent protective film 2. By providing the water vapor barrier layer (hereinafter, may be referred to as "barrier layer"), the infiltration of moisture in the air into the polarizing element 1 is suppressed, so that the polarizing plate is exposed to a high temperature and high humidity environment. Even in this case, yellowing due to deterioration of the polarizing element can be prevented. The moisture permeability of the barrier layer 3 is preferably 0.5 g / ^m 2.24 h or less, more preferably 0.3 g / ^m 2.24 h or less, and even ^more preferably 0.2 / m 2.24 h or less. From the viewpoint of preventing deterioration of the stator, the smaller the moisture permeability of the barrier layer 3, the more preferable. The lower limit of the moisture permeability of the barrier layer 3 is not particularly limited, but is generally 1.0 × 10 ^-4 g / ^m 2.24 h or more. From the viewpoint of releasing the outgas generated from the transparent protective film 2 and the like, the moisture permeability of the barrier layer 3 is preferably 1.0 × ^-3 g / ^m 2.24 h or more.

Moisture permeability is measured by Annex B (Mocon method) of JIS K 7129: 2008 under the conditions of a temperature of 40 ° C. and a relative humidity difference of 90%. Since the barrier layer 3 is a thin film and it is difficult to measure the moisture permeability by itself, the moisture permeability of the laminate in which the barrier layer 3 is provided on the transparent protective film 2 is regarded as the moisture permeability of the barrier layer 3. .. The moisture permeability of the polarizing plate 101 provided with the barrier layer 3 on the transparent protective film 2 may be used as the moisture permeability of the barrier layer 3. Since the polarizing element 1 and the transparent protective films 2 and 15 are resin materials and have a sufficiently high moisture permeability as compared with the water vapor barrier layer 3, the moisture permeability of the laminate in which the barrier layer 3 is provided on these films is a barrier. It can be regarded as equal to the moisture permeability of the layer 3 alone.

The material of the barrier layer 3 is not particularly limited as long as it exhibits the above-mentioned moisture permeability, but it is preferably an inorganic thin film, and is a ceramic material such as a metal or semimetal oxide, a nitride, or an oxynitride. Is preferable. In particular, oxides, nitrides or oxynitrides of Si, Al, In, Sn, Zn, Ti, Nb, Ce or Zr are preferable because they have both low moisture permeability and transparency. The barrier layer 3 may be a ceramic material containing a plurality of (semi) metal elements. Of these, silicon oxide, silicon oxynitride, silicon nitride, and aluminum oxide are preferable. The barrier layer may have a laminated structure of two or more layers.

The thickness of the barrier layer 3 is not particularly limited. From the viewpoint of enhancing the water vapor barrier property, it is preferable that the barrier layer 3 has a large film thickness. On the other hand, if the film thickness of the barrier layer 3 is excessively large, it may cause cracks, decrease in production efficiency, and increase in cost. The film thickness of the barrier layer 3 is, for example, 10 to 300 nm, preferably 20 to 250 nm, more preferably 30 to 200 nm, and even more preferably 40 to 150 nm.

The barrier layer 3 may be a single-layer film composed of only one layer or a multilayer film composed of two or more layers. When the barrier layer 3 is a multilayer film, the barrier layer 3 functions as an optical interference layer by appropriately selecting the laminated structure (number of layers, refractive index and film thickness of each layer), and the pressure-sensitive adhesive layer 8 and the barrier layer are formed. Reflection at the interface with 3 and the interface between the barrier layer 3 and the transparent protective film 2 can be reduced. Examples of the barrier layer of the multilayer film include a laminated structure of a high refractive index layer having a refractive index of about 1.8 to 2.5 and a low refractive index layer having a refractive index of about 1.3 to 1.5. Be done.

The barrier layer 3 may include a primer layer in contact with the transparent protective film 2. The primer layer has a function of enhancing the adhesion of the barrier layer to the transparent protective film 2, and like the primer layer 50 described later, a metal, a metal oxide, a fluoride, a sulfide, a nitride or the like is used. Be done.

The formation of the barrier layer 3 on the transparent protective film 2 may be performed before the transparent protective film 2 is attached to the polarizing element 1, or the transparent protective film 2 and the polarizing element 1 are attached to each other to form a polarizing plate. It may be carried out later. When the transparent protective film 2 and the polarizing element 1 are bonded to each other using an aqueous adhesive, the classifier 2 and the polarizing element 2 are used from the viewpoint of suppressing poor adhesion and appearance defects such as unevenness due to the retention of water at the bonding interface. It is preferable to form the barrier layer 3 on the transparent protective film after the transparent protective film 2 is bonded to the transparent protective film 2.

The method for forming the barrier layer 3 is not particularly limited, and a dry coating method or a wet coating method may be used. Since a film having a high film density and a high water vapor barrier property is easily formed, a dry process such as a sputtering method, an ion plating method, a vacuum vapor deposition method, or a CVD method is preferable, and among them, a dense film can be formed. The sputtering method is preferable.

In the sputtering method, a roll-to-roll method enables continuous film formation of a thin film while conveying a long film in one direction (longitudinal direction). Therefore, the productivity of the polarizing plate provided with the barrier layer 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 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 metal target. In order to form a metal oxide at a high rate, reactive sputtering using a metal target is preferable. When forming a nitride or an oxynitride, the film may be formed while introducing nitrogen gas.

In sputter film formation, it is preferable to control the substrate temperature in the range of −20 to 180 ° C. By increasing the substrate temperature, a dense film is likely to be formed, and the moisture permeability of the barrier layer tends to decrease. On the other hand, if the substrate temperature is excessively high, it may cause poor running of the film and wrinkles.

When forming a silicon-based ceramic layer such as silicon oxide, silicon nitride, or silicon oxynitride by the sputtering method, the water pressure is 1. In addition to the sputtering gas such as argon and the reactive gas such as oxygen and nitrogen. It is preferable to carry out the film formation while introducing water so that the range is about 0 × 10 ^-4 to 1.0 × 10 ^-2 Pa. The film forming pressure in the sputter film formation is about 0.05 to 1 Pa, preferably about 0.1 to 0.5 Pa.

As described above, by forming the thin film on the transparent protective film 2 having few surface irregularities and a small arithmetic mean height Sa, the barrier layer 3 having low moisture permeability is likely to be formed. Further, by forming the barrier layer 3 on the transparent protective film 2 having a small hygroscopic expansion rate, even when the polarizing plate is exposed to a high temperature and high humidity environment, the barrier layer 3 is less likely to crack, and the polarization caused by moisture is generated. Deterioration of child 1 (mainly yellowing) tends to be suppressed.

[Anti-reflective film]
The antireflection film 105 is provided with an antireflection layer 5 on the first main surface of the transparent film base material 4 via a primer layer 50, if necessary. The antireflection layer is a laminated body of two or more thin films, and in FIG. 1, an antireflection layer 5 composed of a laminated body of four thin films 51, 52, 53, 54 is shown.

<Transparent film base material>
The transparent film base material 4 includes the transparent film 41. It is preferable that the hard coat layer 42 is provided on the first main surface (antireflection layer 5 forming surface) of the transparent film 41.

The visible light transmittance of the transparent film substrate 4 is preferably 80% or more, more preferably 90% or more. The thickness of the transparent film base material 4 is not particularly limited, but is preferably about 5 to 200 μm, more preferably 10 to 150 μm, still more preferably 40 to 100 μm, from the viewpoint of workability such as strength and handleability, and thin layer property. ..

As the resin material constituting the transparent film 41, the same material as described above is preferably used as the material of the transparent protective film. In the polarizing plate with an antireflection layer, by providing the barrier layer 3 on the transparent protective film 2 of the polarizing plate 101, deterioration of the polarizing element due to the infiltration of water is suppressed. Therefore, the antireflection film does not need to have a water vapor barrier property, and the transparent film 41 is not required to have smoothness. Further, the transparent film 41 is bonded to the barrier layer 3 via the pressure-sensitive adhesive layer 8, and even if the transparent film 41 changes in size due to moisture absorption and expansion, the stress at the interface is relaxed, so that the transparent film 41 has low moisture absorption and expansion. Is not required. Therefore, as the material of the transparent film 41, a highly hygroscopic material such as a cellulosic resin (for example, triacetyl cellulose) may be used.

It is preferable that the surface of the transparent film 41 is provided with the hard coat layer 42. By providing the hard coat layer 42 on the antireflection layer 5 forming surface side of the transparent film base material 4, it is possible to improve the mechanical properties such as the hardness and elastic modulus of the antireflection layer 5. The hard coat layer 42 preferably has a high surface hardness and excellent scratch resistance. The hard coat layer 42 can be formed, for example, by applying a solution containing a curable resin onto the transparent film 41. When a curable resin is used, it is preferable to perform curing by heating or irradiation with active light after application.

Examples of the curable resin include thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Examples of the curable resin 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 resins. Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferable, and acrylic urethane resins are particularly preferable, because they have high hardness, can be cured by ultraviolet rays, and are excellent in productivity.

The hard coat layer 42 may contain fine particles. For example, by including fine particles in the hard coat layer, unevenness may be formed on the surface of the hard coat layer 42 to provide antiglare property. The fine particles used to impart antiglare properties are preferably microparticles having a particle size on the order of μm. The average particle size of the microparticles is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

By forming fine irregularities on the surface of the hard coat layer 42, the adhesion to the antireflection layer 5 (or the primer layer 50) provided on the hard coat layer 42 tends to be improved. The fine particles used for forming irregularities on the surface of the hard coat layer 42 having excellent adhesion to thin films such as the primer layer 50 and the antireflection layer 5 are preferably nanoparticles having a particle size on the order of nm. .. The average particle size of the nanoparticles is preferably 10 to 150 nm, more preferably 20 to 100 nm, still more preferably 25 to 80 nm.

The shape of the fine particles is not particularly limited, but a spherical shape having an aspect ratio of 1.5 or less is preferable. The aspect ratio of the particles is more preferably 1.2 or less, and even more preferably 1.1 or less. The content ratio of the fine particles in the hard coat layer is about 1 to 60% by weight, and may be adjusted according to the type of fine particles and the purpose of addition.

The fine particles 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; polymethylmethacrylate, polystyrene, polyurethane, and acrylic-styrene copolymer weight. Crosslinked or uncrosslinked organic fine particles made of various transparent polymers such as coalesced, benzoguanamine, melamine, and polycarbonate; transparent fine particles such as silicone fine particles can be used without particular limitation. Inorganic oxides are preferable as the nanoparticles. A functional group such as an acrylic group or an epoxy group may be introduced on the surface of the inorganic oxide particles for the purpose of enhancing the adhesion and affinity with the resin.

The thickness of the hard coat layer 42 is not particularly limited, but in order to achieve high hardness, it is preferably 1 μm or more, more preferably 1.5 μm or more, still more preferably 2 μm or more. Considering the ease of formation by coating, the thickness of the hard coat layer is preferably 15 μm or less, more preferably 10 μm or less, still more preferably 8 μm or less.

The surface of the transparent film base material 4 is coated with a corona treatment, a plasma treatment, a frame treatment, an ozone treatment, a primer treatment, a glow treatment, a saponification treatment, and a coupling agent for the purpose of improving the adhesion with the antireflection layer 5. Surface modification treatment such as treatment may be performed. For example, by performing plasma treatment in a vacuum, the surface of the base material is modified and appropriate irregularities are formed on the surface, so that the transparent film base material 4 (hard coat layer 42) and the antireflection layer 5 ( Alternatively, the adhesion to the primer layer 50) tends to be improved.

As described above, in the polarizing plate with the antireflection layer, it is not necessary to give the antireflection layer 5 a water vapor barrier property, so that the surface of the transparent film base material 4 which is the base of the antireflection layer 5 is provided with irregularities. You may. Therefore, the arithmetic mean height of the second main surface of the transparent film base material 4 may be larger than the arithmetic average height of the first main surface of the transparent protective film 2. When the arithmetic average height Sa of the first main surface of the transparent film base material 4 is large, the adhesion of the antireflection layer 5 on the transparent film base material 4 tends to be improved.

From the viewpoint of improving the adhesion of the antireflection layer 5 (and the primer layer 50), the arithmetic average height Sa of the first main surface of the transparent film base material 4 is preferably 1.5 nm or more. The arithmetic mean height Sa of the first main surface of the transparent film substrate 4 may be 2 nm or more, 2.5 nm or more, or 3 nm or more. On the other hand, if the surface unevenness becomes rough, sufficient adhesion may not be realized. Therefore, the arithmetic average height Sa of the first main surface of the transparent film base material 4 is preferably 8 nm or less, more preferably 7.5 nm or less, still more preferably 7 nm or less. By adjusting the particle size and content of the fine particles (particularly nanoparticles), the uneven shape of the surface of the hard coat layer 42 can be adjusted. Further, it is also possible to increase the arithmetic mean height Sa of the first main surface of the hard coat layer 42 by dry etching such as plasma treatment.

<Primer layer>
A primer layer 50 may be provided on the hard coat layer 42. Examples of the material constituting the primer layer 50 include metals such as silicon, nickel, chromium, tin, gold, silver, platinum, zinc, titanium, tungsten, aluminum, zirconium, and palladium; alloys of these metals; these metals. Oxides, fluorides, sulfides or nitrides; etc. Of these, oxide is preferable as the material of the primer layer, and silicon oxide is particularly preferable. Since silicon oxide has a small refractive index, it is possible to reduce the reflection of visible light at the interface between the transparent film base material 4 (hard coat layer 42) and the primer layer 50.

The primer layer 50 is preferably an inorganic oxide layer, and may be an oxide layer having a smaller amount of oxygen than the stoichiometric composition. Among the inorganic oxides having a non-stoichiometric composition, silicon oxide represented by the composition formula SiOx (0.5 ≦ x <2) is preferable. In particular, by providing the silicon oxide layer having a non-stoichiometric composition as the primer layer 50 on the hard coat layer 42 containing silica particles as nanoparticles, the primer layer 50 is firmly adhered to the hard coat layer 42. Can be done.

The thickness of the primer layer 50 is, for example, about 1 to 20 nm, preferably 2 to 15 nm, and more preferably 3 to 15 nm. When the film thickness of the primer layer is within the above range, it is possible to achieve both improvement in adhesion and light transmission.

<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. Examples of the material of the thin film constituting the antireflection layer 5 include metal oxides, nitrides, and fluorides. 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 transparent film substrate 4) 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.

The method for forming the thin film constituting the primer layer 50 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. Above all, the sputter method is preferable because it is excellent in the uniformity of the film thickness.

<Anti-fouling layer>
The antireflection film 105 may have an additional functional layer on the antireflection layer 5. For example, the antifouling layer 6 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 6 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. Is 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 or a gravure coating method, or a dry process such as a vacuum vapor deposition method or a CVD method. The thickness of the antifouling layer 6 is usually about 1 to 50 nm, preferably 2 to 30 nm, and more preferably 3 to 20 nm.

[Polarizer with antireflection layer]
A polarizing plate with an antireflection layer can be obtained by bonding the second main surface of the antireflection film 105 to the first main surface (on the barrier layer 3) of the polarizing plate 101 with a barrier layer via the pressure-sensitive adhesive layer 8. ..

As the pressure-sensitive adhesive layer 8, a material having a high visible light transmittance is preferably used. For example, an acrylic pressure-sensitive adhesive has excellent optical transparency, exhibits appropriate wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance, heat resistance, and the like. Therefore, the polarizing plate 101 and the antireflection film 105 are attached. It is suitable as a material for the pressure-sensitive adhesive layer 8 used for the combination. The thickness of the pressure-sensitive adhesive layer 8 is generally about 5 to 100 μm, preferably about 10 to 50 μm.

In the polarizing plate with an antireflection layer in which the antireflection film 105 is bonded on the polarizing plate 101 with a barrier layer, the low moisture permeability barrier layer 3 blocks the infiltration of moisture into the polarizing element 1, so that the moisture in the air It is possible to suppress the deterioration of the polarizing element 1 due to the above. Even if the antireflection layer 5 provided on the surface is finely scratched, the barrier layer 3 suppresses the infiltration of water into the stator, so that the decoder is less likely to deteriorate and has excellent moisture and heat resistance. It is preferable that the polarizing plate with an antireflection layer has a small amount of change in b ^* when exposed to a high temperature and high humidity environment. b ^* is the chromaticity in the La ^* b ^* color space, and the larger the chromaticity b ^* of the transmitted light, the more the transmitted light is colored yellow and visually recognized.

When a polarizing element using iodine as a bicolor substance is exposed to a high temperature and high humidity environment, the balance of iodine ions (I _3- ^and I _5- ⁾ is lost and the transmittance in the short wavelength region of visible light becomes small. , Yellowing and b ^* tend to increase. Therefore, the amount of change in b ^* is an index showing the deterioration of the stator due to moisture, and the smaller the amount of change in b ^* , the higher the durability.

The change in the chromaticity b ^* value of the single transmitted light when the polarizing plate with the antireflection layer is allowed to stand in an environment of 65 ° C. and 90% for 72 hours is preferably 1.5 or less, preferably 1.3 or less. More preferably, 1.0 or less is further preferable, and 0.5 or less is particularly preferable. The change in the chromaticity b ^* of the single transmitted light of the polarizing plate with an antireflection layer when left in an environment of 65 ° C. and 90% for 240 hours is preferably 1.8 or less, more preferably 1.5 or less. It is preferably 1.0 or less, more preferably 0.5 or less, and particularly preferably 0.5 or less.

The smaller the amount of change in b ^* , the more preferable. As described above, by forming the barrier layer 3 on the film 2 having a small arithmetic mean height Sa, the moisture permeability of the barrier layer 3 tends to decrease, and the increase in b ^* (yellowing of the polarizing element) tends to occur. It is suppressed. Further, by forming the barrier layer 3 on the film 2 having a small hygroscopic expansion, cracks are less likely to occur in the barrier layer, and deterioration of the stator due to the infiltration of water from the cracks tends to be suppressed.

Since the polarizing plate with an antireflection layer is provided with the antireflection layer 5 on the surface, it prevents the reflection of external light in the image display device and contributes to the improvement of the visibility of the displayed image. Light incident from the second main surface side is also reflected at the interface between other layers. In particular, at the interface between the barrier layer 3 and the pressure-sensitive adhesive layer 8, reflection is likely to occur due to the difference in refractive index, so it is preferable to reduce the reflectance at the interface.

The interfacial reflectance between the barrier layer 3 and the pressure-sensitive adhesive layer 8 is preferably 1% or less, more preferably 0.5% or less, further preferably 0.2% or less, and 0.15% or less or 0.1% or less. May be. _The interfacial reflectance is determined by the positive reflectance Y1 (%) of the polarizing plate with the antireflection layer in which the antireflection film 105 is bonded to the surface of the barrier layer 3 of the polarizing plate 101 via the pressure-sensitive adhesive layer 8 and the polarizing plate. The difference from the normal reflectance Y ₀ (%) of the antireflection film 105 before bonding is Y ₁ − Y ₀ . The specular reflectances Y ₀ and Y ₁ were obtained by measuring the specular reflection stock twice in the field using a sample in which a black acrylic plate was attached to the back surface of the sample via an adhesive layer to eliminate the back surface reflection. It is a Y value obtained by visual sensitivity correction from the spectrum.

[Image display device]
The polarizing plate with an antireflection layer is used, for example, by arranging it on the surface of an image display device such as a liquid crystal display or an organic EL display. For example, the image display device 300 is formed by bonding the second main surface of the polarizing plate 101 onto the image display medium 110 such as a liquid crystal cell or an organic EL cell via the pressure-sensitive adhesive layer 9. By arranging a polarizing plate with an antireflection layer on the surface on the viewing side, it is possible to reduce the reflection of external light and improve the visibility of the image display device. Since the low moisture permeability barrier layer 3 is provided on the second main surface of the polarizing plate 101, even if the antireflection layer 5 is scratched when the image display device is used, the moisture content to the polarizing element 1 is reached. It is possible to suppress the infiltration of the image, and even when exposed to a high temperature and high humidity environment, it is possible to obtain an image display device having excellent durability, which is less likely to cause deterioration of display characteristics and display unevenness due to deterioration of the polarizing element.

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

[Example 1]
<Manufacturing of polarizing plate>
One side of an amorphous polyester film (polyethylene-terephthalate / isophthalate; glass transition temperature 75 ° C.) having a thickness of 100 μm is subjected to corona treatment, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) is applied to the corona-treated surface. ) And acetacetyl-modified polyvinyl alcohol (Nippon Synthetic Chemical Industry "Gosefimer Z200"; degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more) at a weight ratio of 9: 1. The containing aqueous solution was applied and dried at 25 ° C. to prepare a laminated body in which a PVA-based resin layer having a thickness of 11 μm was provided on an amorphous polyester film substrate.

This laminate was uniaxially stretched at the free end 2.0 times in the longitudinal direction by aerial auxiliary stretching in an oven at 120 ° C., and then rolled into a 4% boric acid aqueous solution at 30 ° C. for 30 seconds at 30 ° C. Was sequentially immersed in the staining solution (0.2% iodine, 1.0% potassium iodide aqueous solution) for 60 seconds. Next, while transporting the laminate in a roll, the laminate was immersed in a cross-linking solution (potassium iodide 3%, boric acid 3% aqueous solution) for 30 seconds for cross-linking treatment, and 70 ° C. boric acid 4%, iodide. While immersed in a 5% aqueous solution of potassium, free-end uniaxial stretching was performed in the longitudinal direction so that the total stretching ratio was 5.5 times. Then, the laminate was immersed in a cleaning solution (4% potassium iodide aqueous solution) at 30 ° C. to obtain a laminate in which a PVA-based polarizing element having a thickness of 5 μm was provided on an amorphous polyester film substrate.

It contains 40 parts by weight of N-hydroxyethylacrylamide and 60 parts by weight of acryloylmorpholin as curable components, and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (BASF) as a polymerization initiator. Manufactured by "Irgacure 819") An ultraviolet curable adhesive containing 3 parts by weight was prepared. This adhesive is applied to the surface of the polarizing element of the above-mentioned laminated body to a thickness of about 1 μm, and a hard coat layer having a thickness of 3 μm is formed on one side thereof. The formed surfaces were bonded together and irradiated with ultraviolet rays having an integrated light amount of 1000 / mJ / cm ² to cure the adhesive. As the acrylic film, a film containing an acrylic resin having a lactone ring structure as a main component was used.

The amorphous polyester film base material is peeled off from the laminate, and the above-mentioned active energy ray-curable adhesive solution is applied to the surface of the PVA resin layer from which the film base material has been peeled off, and the first retardation layer is applied thereto. Was further bonded, and the above-mentioned active energy ray-curable adhesive was applied thereon to bond the second retardation layer. The first retardation layer is a biaxially stretched cyclic polyolefin film (negative B plate) having an in-plane retardation of 116 nm, and the second retardation layer is a biaxially stretched modified polyethylene film having an in-plane retardation of 35 nm (negative B plate). (Positive B plate), the slow axis direction of the first retardation layer is parallel to the absorption axis direction of the substituent, and the slow axis direction of the second retardation layer is orthogonal to the absorption axis direction of the substituent. It was pasted together so that it would be. In this way, an acrylic film having a hard coat layer on the surface is bonded to one surface of a polarizing element having a thickness of 5 μm, and a first retardation layer and a second phase difference are attached to the other surface of the polarizing element. A polarizing plate having laminated layers was obtained.

(Formation of water vapor barrier layer)
The above polarizing plate was set in a roll-to-roll magnetron sputtering apparatus, and plasma treatment was performed on the hard coat layer forming surface of the polarizing plate while introducing Ar gas. After that, it is oxidized on the hard coat layer by DC magnetron sputtering (input power: 500 W, ultimate vacuum degree: 1 × 10 ^-6 Pa, sputtering gas: Ar, sputtering pressure: 0.50 Pa, substrate temperature: 40 ° C.). A silicon (SiO _x ; x <2) primer layer (thickness: 3 nm) was formed.

Next, DC magnetron sputtering (input power: 20 kW, ultimate vacuum: 1 × 10 ^-4 Pa, sputter gas: O ₂ / Ar = 2/1, sputter pressure: 0.10 Pa, substrate temperature: -40 ° C) ₂ layers of SiO (thickness: 150 nm, refractive index: 1.46) were formed.

<Manufacturing of antireflection film>
(Making a hard coat film)
Organosilica sol (Nissan Chemical Industries, Ltd. "MEK") so that the amount of silica particles in an ultraviolet curable acrylic resin composition (manufactured by DIC, trade name "GSANDIC PC-1070") is 25 parts by weight with respect to 100 parts by weight of the resin component. -ST-L ", average primary particle diameter of silica particles: 50 nm, solid content 30% by weight) was added and mixed to prepare a composition for forming a hard coat layer. This composition was applied to one side of a triacetyl cellulose film having a thickness of 100 μm so as to have a thickness of 3 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.

(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 while being oxidized at a substrate temperature of 40 ° C. to 10 nm. A silicon 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 are sequentially formed on the hard coat layer forming surface to prepare an antireflection film. bottom.

A pure Si target was used to form the primer layer, and sputtering was performed under the conditions of input power: 500 W, sputtering gas: Ar, and sputtering pressure: 0.5 Pa. For the film formation of the Nb ₂ O ₅ layer, an Nb target was used, and sputtering was carried out under the conditions of an input power of 30 kW and a sputtering pressure of 0.5 P. For the film formation of the SiO ₂ layer, a Si target was used, and sputtering was carried out under the conditions of an input power of 20 kW and a sputtering pressure of 0.5 Pa. In the film formation of Nb ₂ O ₅ layer and SiO ₂ layer, argon and oxygen are used as the sputter gas, and the amount of oxygen introduced so that the film formation mode maintains the transition region is adjusted by plasma emission monitoring (PEM) control. bottom.

(Formation of antifouling layer)
A fluororesin solution containing a perfluoroether structure was applied to the surface of the antireflection layer so as to have a thickness of 9 nm after drying to form an antifouling layer as a top coat layer.

<Lamination of polarizing plate and antireflection film>
An acrylic transparent adhesive layer having a thickness of 20 μm was laminated on the film base material (antireflection layer non-formed surface) of the antireflection film to prepare an antireflection film with an adhesive. The polarizing plate and the antireflection film were laminated by laminating the pressure-sensitive adhesive layer of the antireflection film with an adhesive on the barrier layer of the polarizing plate.

[Example 2]
In the production of the polarizing plate, a 40 μm-thick polycarbonate (PC) film provided with a 2 μm hard coat layer was used as the substituent protective film instead of the acrylic film, and one surface of the 5 μm-thick polarizing element was used. A polycarbonate film having a hard coat layer on the surface was bonded, and a polarizing plate in which a first retardation layer and a second retardation layer were bonded to the other surface of the polarizing element was obtained. A polarizing plate was produced in the same manner as in Example 1 except that the polarizing element protective film on the barrier layer forming surface was changed, and an antireflection film was attached to the surface of the barrier layer of the polarizing plate via an adhesive layer. A polarizing plate with an antireflection layer was produced.

[Example 3]
In the production of the polarizing plate, a cyclic polyolefin (COP) film having a thickness of 40 μm is used as the substituent protective film instead of the acrylic film, and the annular polyolefin film is bonded to one surface of the polarizing element having a thickness of 5 μm. Then, a polarizing plate in which the first retardation layer and the second retardation layer were bonded to the other surface of the polarizing element was obtained. A polarizing plate was produced in the same manner as in Example 1 except that the polarizing element protective film on the barrier layer forming surface was changed.

The above polarizing plate was set in a roll-to-roll magnetron sputtering apparatus, and plasma treatment and SiOx primer layer formation were performed in the same manner as in Example 1. After that, DC magnetron sputtering (input power: 20 kW, ultimate vacuum degree: 1 × 10 ^-4 Pa, sputtering gas: O ₂ / Ar / N ₂ = 3/3/1, sputtering pressure: 0.10 Pa, substrate temperature: 40 ° C.) to form _two layers of SiON (thickness: 130 nm, refractive index: 1.65). Then, a SION ₂ layer (thickness: 20 nm) was formed on the SION ₂ layer in the same manner as in Example 1.

A polarizing plate was produced in the same manner as in Example 1 except that the polarizing element protective film and the barrier layer were changed, and an antireflection film was attached to the surface of the barrier layer of the polarizing plate via an adhesive layer. A polarizing plate with an antireflection layer was produced.

[Example 4]
Using the same polarizing plate as in Example 1, plasma treatment was performed on the hard coat layer forming surface as in Example 1, and then DC magnetron sputtering (input power: 20 kW) using a target containing ZnO, Al and SiO ₂ . , Ultimate vacuum degree: 1 × 10 ^-4 Pa, sputtering gas: O ₂ / Ar = 5/100, sputtering pressure: 0.10 Pa, substrate temperature: 40 ° C., composite oxide layer (thickness: 120 nm, refractive index) Rate: 1.65) was formed. Then, the SiO ₂ layer (thickness: 85 nm) was formed by the same method as in Example 1.

[Comparative Example 1]
A polarizing plate was prepared in the same manner as in Example 1 except that the barrier layer was not provided on the surface of the polarizing plate, and the pressure-sensitive adhesive layer was placed on the hard coat layer on the acrylic polarizing element protective film of the polarizing plate. A polarizing plate with an antireflection layer was produced by laminating an antireflection film through the film.

[Comparative Example 2]
In the film formation of the Nb ₂ O ₅ layer and the SiO ₂ layer of the antireflection film, the argon flow rate was reduced and the film was formed at a sputter pressure of 0.1 Pa to prepare a low moisture permeability antireflection film. Other than that, in the same manner as in Comparative Example 1, an antireflection film having low moisture permeability is attached to the hard coat layer on the acrylic polarizing element protective film of the polarizing plate via an adhesive layer, and an antireflection layer is attached. A polarizing plate was produced.

[Comparative Example 3]
In the production of the polarizing plate, a 40 μm-thick triacetyl cellulose (TAC) film provided with a 2 μm hard coat layer was used as the polarizing element protective film instead of the acrylic film, and one surface of the 5 μm thick polarizing element was used. A TAC film having a hard coat layer on the surface was bonded to the polarizing plate, and a first retardation layer and a second retardation layer were bonded to the other surface of the polarizing element to obtain a polarizing plate. A polarizing plate was produced in the same manner as in Example 1 except that the polarizing element protective film on the barrier layer forming surface was changed, and an antireflection film was attached to the surface of the barrier layer of the polarizing plate via an adhesive layer. A polarizing plate with an antireflection layer was produced.

[Comparative Example 4]
The polarizing element protective film on the barrier layer forming surface was changed to a TAC film not provided with a hard coat layer. A polarizing plate with an antireflection layer was produced in the same manner as in Comparative Example 3 except for the above.

[Comparative Example 5]
The polarizing element protective film on the barrier layer forming surface was changed to an acrylic film without a hard coat layer. A polarizing plate with an antireflection layer was produced in the same manner as in Example 1 except for the above.

[evaluation]
<Arithmetic Mean Roughness Sa of Transparent Protective Film>
Using an atomic force microscope (AFM) as a sample of the polarizing element protection film before bonding to the polarizing element and the polarizing plate after plasma treatment (before barrier layer formation), the barrier layer before and after plasma treatment is used under the following conditions. The three-dimensional surface shape of the formed surface (the surface opposite to the surface bonded to the polarizing element) was measured, and the arithmetic average surface roughness Sa was measured according to ISO 25178.
Device: Bruker's "Dimemation 3100", Controller: NanoscopeV
Measurement mode: Tapping mode Cantilever: Si single crystal Measurement field of view: 1 μm × 1 μm

<Humidity permeability>
According to Annex B (Mocon method) of JIS K 7129: 2008, the moisture permeability of the barrier layer and the antireflection film was measured under the conditions of a temperature of 40 ° C. and a relative humidity difference of 90%. The polarizing plates prepared in each Example / Comparative Example were used for measuring the moisture permeability of the barrier layer. Since the moisture permeability of the barrier layer is sufficiently smaller than the moisture permeability of the polarizing plate, the moisture permeability of the sample in which the barrier layer is formed on the polarizing plate is regarded as the moisture permeability of the barrier layer.

<Hygroscopic expansion rate>
A 100 mm × 100 mm square test piece was cut out from the polarizing element protective film before being bonded to the extruder, and allowed to stand for 48 hours under the conditions of a temperature of 23 ° C. and a relative humidity of 65% RH to perform state conditioning. Four reference points (scratches) are formed at intervals of 80 mm in the MD direction (transportation direction during roll transfer) and the TD direction (direction orthogonal to the MD direction), and the distance _L0 between the reference points is measured by the surface coordinate measuring machine. (Measured by TOPCON "CP600S"). After allowing to stand in a constant temperature and humidity chamber having a temperature of 65 ° C. and a relative humidity of 90% for 72 hours, the mixture was allowed to cool to room temperature under the conditions of a temperature of 23 ° C. and a relative humidity of 65% RH, and the distance L between the gauge points was measured. .. For each of MD and TD, the average coefficient of thermal dimensional change at two locations was taken as the coefficient of thermal expansion. In addition, the symbol + of the moisture absorption expansion coefficient represents expansion, and the symbol-represents contraction.

<Single transmittance of polarizing plate with antireflection film>
Using a spectral transmittance measuring device with an integrating sphere (“DOT-3C” manufactured by Murakami Color Technology Research Institute), light was incident from the polarizing plate side to measure the single transmittance of the polarizing plate with an antireflection film. The numerical value of the transmittance is a Y value corrected for luminosity factor by the 2 degree field of view (C light source) of JIS Z8701 with the complete polarization obtained through the Granteller prism as 100%.

<Interfacial reflectance>
A black acrylic plate (manufactured by Mitsubishi Chemical Corporation) having a thickness of 2 mm was attached to the surface of the polarizing plate with an antireflection film on the polarizing plate side via a transparent acrylic adhesive. This sample was irradiated with the light of the D65 light source from the antireflection film side, and the field positive reflected light spectrum was measured twice using a spectrophotometer (“CM2600d” manufactured by Konica Minolta). The reflection Y value (Y ₁ ) was calculated. Similarly, the reflection Y value (Y ₀ ) was obtained for a sample in which a black acrylic plate having a thickness of 2 mm was bonded to the surface of the antireflection film on the transparent film side before bonding with the polarizing plate via a transparent acrylic adhesive. rice field. _The difference Y1 _−Y0 between the normal reflectance _Y1 of the polarizing plate with the antireflection film and the normal reflectance _Y0 of the antireflection film is set on the surface of the polarizing plate (if the barrier layer is provided, the barrier layer). Interfacial) Reflectance.

<High temperature and high humidity durability test of polarizing plate with antireflection layer>
(Preparation of sample)
A polarizing plate with an antireflection layer was cut out to a size of 5 cm in the MD direction × 10 cm in the TD direction, and the surface on the polarizing plate side was attached to a glass plate via a transparent acrylic pressure-sensitive adhesive. A load of 300 g was applied to the surface (antireflection layer) of this sample with # 1200 sandpaper (25 mmφ), and the sample was reciprocated once in the TD direction with a length of 5 cm to scratch the antireflection layer. The right half of the sample was designated as the "scratched area" and the left half was designated as the "scratched area".

(Hue change)
Using a spectral transmittance measuring device with an integrating sphere (“DOT-3C” manufactured by Murakami Color Technology Research Institute), light is incident from the polarizing plate side (glass plate side) to detect the transmitted light of the polarizing plate with antireflection film. The chromaticity b ^* ₀ was measured. Then, it was allowed to stand for 72 hours in a constant temperature and humidity chamber having a temperature of 65 ° C. and a relative humidity of 90%, and allowed to cool to room temperature. The transmitted light chromaticity b ^* ₁ was measured around the scratches in the scratched area and in the scratch-free area, and the amount of change in b ^* before and after the high-temperature and high-humidity durability test Δb ^* = b ^* ₁ -b ^* ₀ was calculated. ..

(village)
The sample after the above high temperature and high humidity durability test was placed on a light table, and the presence or absence of color unevenness around the scratches in the scratched area was visually confirmed and evaluated according to the following criteria.
〇: No yellowing and no unevenness is confirmed △: The whole is yellowed and the presence or absence of unevenness cannot be confirmed ×: Unevenness is clearly confirmed around the scratch

The scratch-free region of the sample after the high-temperature and high-humidity durability test was reflected and observed with an optical microscope (objective lens: 20 times) in a field of view of 600 μm × 500 μm to observe the presence or absence of cracks in the barrier layer. Those without cracks were marked with "○", and those with cracks were marked with "x".

[Evaluation results]
Table 1 shows the configurations and evaluation results of the polarizing plates with the antireflection layer of the above-mentioned Examples and Comparative Examples.

In Comparative Example 1 in which the antireflection film was attached without providing the barrier layer on the polarizing element protective film, b ^* increased in both the scratched region and the scratch-free region after the high-temperature and high-humidity durability test. In Comparative Example 2 in which an antireflection film having a low moisture permeability was attached without providing a barrier layer on the polarizing element protective film, good durability was shown in a scratch-free region, but a high-temperature and high-humidity durability test was performed in a scratched region. Later, an increase in b ^* was seen.

From these results, it is considered that in Comparative Example 1, since the water vapor barrier effect of the antireflection layer is not sufficient, the polarizing plate turns yellow and b ^* rises when exposed to a high temperature and high humidity environment. In Comparative Example 2, since the antireflection layer has low moisture permeability, it shows excellent durability when the antireflection layer is not scratched, but when the antireflection layer is scratched, moisture infiltrates from there. It is considered that b ^* increased due to the yellowing of the polarizing element.

In Examples 1 to 4 in which a barrier layer was provided on the polarizing element protective film and an antireflection film was laminated on the barrier layer, the change in b ^* after the high temperature and high humidity durability test was observed in both the scratched region and the scratch-free region. It can be seen that it is small and shows excellent durability.

In Comparative Example 3, b ^* increased after the high-temperature and high-humidity durability test, even though the same barrier layer as in Example 1 was provided on the TAC film as the polarizing element protective film. Further, in Comparative Example 3, cracks were generated in the barrier layer after the high temperature and high humidity durability test. A similar tendency was observed in Comparative Example 4 in which a TAC film having no hard layer was used as the polarizing element protection film. In Comparative Examples 3 and 4, since the dimensional change of the film used as the base for forming the barrier layer was large, cracks were generated in the barrier layer and the water vapor barrier property could not be guaranteed, which caused yellowing and unevenness of the polarizing plate. It is thought to be the cause.

In Comparative Example 5 in which the barrier layer was provided on the acrylic film without the hard coat layer, the barrier layer was different from that in Example 1 even though the material and the thickness of the thin films constituting the barrier layer were the same. The moisture permeability was reduced, and the high-temperature and high-humidity durability of the polarizing plate with an antireflection layer was also reduced. In Example 3, since the moisture permeability of the barrier layer is low even though the COP film as the polarizing element protective film is not provided with the hard coat layer, the presence or absence of the hard coat layer directly determines the moisture permeability of the barrier layer. In Example 1, the surface roughness Sa was reduced by providing the hard coat layer, and the moisture permeability was reduced by providing the barrier layer on the hard coat layer, and the durability of the polarizing plate was improved. it is conceivable that.

From the comparison between Comparative Example 1 and Example 4, it can be seen that when the barrier layer is provided, the reflectance on the surface of the polarizing plate tends to be high. On the other hand, from the comparison between Example 4 and Example 1, by adjusting the laminated structure of the barrier layer, the reflectance of the interface can be reduced even when the barrier layer is provided, and excellent visibility can be realized. I understand.

300 Image display device 200 Polarizing plate with antireflection layer 101 Polarizing plate with barrier layer 1 Polarizer 2 Transparent protective film 21 Transparent film 22 Coating layer (smoothing layer)
3 Water vapor barrier layer 15 Polarizer protective film 105 Antireflection film 4 Transparent film base material 41 Transparent film 42 Hard coat layer 50 Primer layer 5 Antireflection layer 51,53 Low refractive index layer 52,54 High refractive index layer 6 Antifouling layer 8, 9 Adhesive layer 110 Image display medium

Claims (12)

A polarizing plate with an antireflection layer in which a polarizing plate and an antireflection film are laminated.
A polarizing plate, a first transparent protective film bonded to the first main surface of the polarizing element, and a polarizing plate having a water vapor barrier layer provided on the first main surface of the first transparent protective film;
An antireflection film comprising a transparent film substrate and an antireflection layer provided on the first main surface of the transparent film substrate; and an adhesive layer disposed between the polarizing plate and the antireflection film.
Equipped with
The water vapor barrier layer of the polarizing plate and the second main surface of the transparent film base material are bonded to each other via the pressure-sensitive adhesive layer.
The moisture absorption expansion coefficient of the first transparent protective film is 0.10% or less, and the moisture absorption expansion rate is 0.10% or less.
The arithmetic mean height Sa of the first main surface of the first transparent protective film is 1.5 nm or less.
The moisture permeability of the water vapor barrier layer is ¹ g / m 2.24 h or less.
Polarizing plate with antireflection layer. The water vapor barrier layer is a ceramic layer containing an oxide, a nitride or an oxynitride of one or more elements selected from the group consisting of Si, Al, In, Sn, Zn, Ti, Nb, Ce and Zr. The polarizing plate with an antireflection layer according to claim 1. The polarizing plate with an antireflection layer according to claim 2, wherein the water vapor barrier layer is a sputtering film. The polarizing plate with an antireflection layer according to any one of claims 1 to 3, wherein the first transparent protective film is provided with a smoothing coating layer on the first main surface of the transparent film. The polarizing plate with an antireflection layer according to any one of claims 1 to 4, wherein the polarizing plate includes a second transparent protective film bonded to the second main surface of the polarizing element. The polarizing plate with an antireflection layer according to any one of claims 1 to 5, wherein the interfacial reflectance between the water vapor barrier layer and the pressure-sensitive adhesive layer is 1% or less. The polarizing plate with an antireflection layer according to any one of claims 1 to 6, wherein the antireflection layer is a laminate of a plurality of thin films having different refractive indexes. The polarizing plate with an antireflection layer according to any one of claims 1 to 7, wherein the antireflection layer is a sputtering film. The polarizing plate with an antireflection layer according to any one of claims 1 to 8, wherein the antireflection film is provided with an antifouling layer on the antireflection layer. The polarizing plate with an antireflection layer according to any one of claims 1 to 9, wherein the antireflection film includes a primer layer between the transparent film base material and the antireflection layer. The polarizing plate with an antireflection layer according to any one of claims 1 to 10, wherein the transparent film base material has a hard coat layer on the first main surface of the transparent film. An image display device in which the polarizing plate with an antireflection layer according to any one of claims 1 to 11 is arranged on the visible side surface of the image display medium.

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