WO2016021732A1 - Antireflective film and manufacturing method thereof, and method of measuring reflected light characteristics of antireflective film - Google Patents

Abstract

This method involves a laminate preparation step for preparing a laminate (40) comprising a film substrate (20) removably adhered to the second primary surface of a transparent film (10) with an adhesive layer (30) interposed therebetween, an antireflective layer formation step in which an antireflective layer (50) comprising two or more thin films is formed on the first primary surface of the transparent film, and an in-line inspection step in which, after deposition of at least one layer of the thin films constituting the antireflective layer, visible light is irradiated from the first primary surface side of the laminate and the light reflected therefrom is detected. The laminate comprising the film substrate (20) and the adhesive layer (30) has a visible light transmittance of 40% or less. The antireflective layer formation step and the in-line inspection step are performed continuously while conveying the laminate (40) in one direction. The deposition conditions of the thin films in the antireflective layer formation step are ideally adjusted in accordance with the detection result in the in-line inspection step.

Description

Antireflection film, method for producing the same, and method for measuring reflected light characteristics of antireflection film

The present invention relates to an antireflection film having an antireflection layer on a transparent film and a method for producing the same. The present invention also relates to a method for measuring the reflected light characteristics of an antireflection film in-line.

An antireflection film is used on the viewing side surface of an image display device such as a liquid crystal display or an organic EL display for the purpose of preventing deterioration in image quality due to reflection of external light or reflection of an image, and improving contrast. The antireflection film includes an antireflection layer formed of a laminate of a plurality of thin films having different refractive indexes on a transparent film.

An example of an antireflection film is a polarizing plate with an antireflection layer. A polarizing plate with an antireflection layer is formed by laminating an antireflection film on the surface of the polarizing plate, or laminating an antireflection film as a protective film on the surface of the polarizer. In addition, a method of forming a polarizing plate with an antireflection layer by forming an antireflection layer on the polarizing plate is also known (for example, Patent Document 1).

JP-A-8-136730

The antireflection layer uses the multiple reflection interference of the thin film to reduce the reflectance of visible light. Therefore, when the refractive index or film thickness of the thin film varies, the reflected light characteristics such as reflectance and reflected light hue change. Even when the film formation conditions of the thin film are strictly controlled and kept constant in the formation of the antireflection layer, the film thickness of the thin film The refractive index and the like vary slightly. Such slight fluctuations have little influence on the reflected light characteristics. Therefore, in general, film formation is performed under certain conditions, and quality control of the antireflection film is performed offline by checking the reflected light characteristics with an inspection device such as a spectrophotometer or visually after film formation. .

In recent years, the demand for antireflection films has increased with the progress of high-definition displays, and there has been a demand for antireflection films with lower reflectance and less colored reflected light. Attempts have also been made to neutralize the light emitted from the panel by adjusting the hue of the reflected light. For example, when light emitted from the panel is yellowish, neutralization is performed by using an antireflection film whose reflected light is bluish.

With such an increase in required characteristics, it is required to more strictly manage the reflected light characteristics of the antireflection film. For this reason, there are cases where the antireflection film deviates from the quality standard due to a change in reflected light characteristics caused by slight fluctuations in manufacturing conditions. Therefore, in the manufacturing process of the antireflection film, it is necessary to control the film forming conditions more strictly to suppress the variation in the refractive index and film thickness of the thin film and to keep the reflected light characteristic constant.

In film production, in-line measurement is performed during the production process, and the quality of the film is kept constant by feeding back the measurement result to the previous process. However, the thickness of the thin film constituting the antireflection layer is several nm to several tens of nm, and it is not easy to directly measure the thickness. In particular, it is extremely difficult to measure the thickness of each thin film in a laminate of a plurality of thin films. In film production, a product is cut out at the start of production (line start) or during the process, the cut out product is inspected offline, and the result is fed back to the production process. However, since a thin film such as an antireflection layer is formed by a vacuum process such as sputtering, vacuum deposition, or CVD, the product cannot be sampled at the start of the line or during the process.

As an in-line inspection in the production process of the antireflection film, it is conceivable to measure the reflected light characteristics in-line and feed back the measurement results to the film forming conditions of the thin film. However, in the measurement of the reflected light characteristic of the antireflection film in-line, the influence of back surface reflection becomes a problem.

In general, an antireflection film is designed such that the visible light reflectance of the antireflection layer-forming surface is 1% or less, whereas it is visible on the back side of the transparent film (the interface between the transparent film and air). The light reflectance is about 4%. In the off-line inspection after the formation of the antireflection layer, it is relatively easy to measure the reflected light characteristics on the front surface side while eliminating the influence of back surface reflection. On the other hand, in the in-line inspection of the antireflection film, since the measurement is performed by irradiating light to the film running in the air or in the vacuum, it is not easy to eliminate the back surface reflection. When backside reflection is involved, most of the reflected light detected by in-line inspection is reflected from the backside, and is detected even if the reflected light characteristics (reflection hue, etc.) from the antireflection layer forming surface change. The reflected light hardly changes. Therefore, it is not easy to accurately measure the reflected light characteristics from the antireflection layer forming surface side in-line.

Patent Document 1 proposes a method of measuring the reflectance by arranging a polarizer (analyzer) on the antireflection layer forming surface side of the polarizing plate when forming the antireflection layer on the surface of the polarizing plate. Yes. If the polarizing plate with the antireflection layer and the analyzer are arranged so that the absorption axis directions of both are orthogonal, the reflected light on the back side of the polarizing plate with the antireflection layer is absorbed by the analyzer, so that the back surface reflection The reflected light characteristics on the surface side can be measured by eliminating the influence of.

However, this method is not applicable except when an antireflection layer is formed on the polarizing plate. The polarizing plate has a configuration in which a transparent film is laminated on both sides of a polarizer, and is more expensive than a transparent film alone. For this reason, in the method of forming an antireflection layer on a polarizing plate, production due to process loss occurs when a non-standard part occurs at the initial stage of the formation of the antireflection layer (before the start of film formation condition control by inline reflected light detection). The increase in cost tends to be remarkable. In addition, the characteristics of the polarizing plate may deteriorate due to the film formation environment of the antireflection layer. For example, when a polarizing plate is introduced into a sputter deposition apparatus, the polarizer may be deteriorated by being exposed to a high-temperature environment or high-power plasma.

Therefore, from the viewpoint of productivity improvement and cost reduction, there is a need for a method for accurately measuring reflected light characteristics by eliminating the influence of back reflection in the formation of an antireflection layer on a transparent film not containing a polarizer. ing. In the present invention, the reflection process with excellent uniformity is achieved by more accurately detecting the change in reflected light characteristics in-line in the process of forming the antireflection layer on the transparent film, and reflecting the detection result in the film formation conditions. It aims at obtaining a prevention film. Moreover, this invention aims at provision of the method of measuring the reflected light characteristic of an antireflection film in-line.

As a result of consideration in view of the above, by using a laminate in which a light-absorbing film base material is detachably attached to the back surface side of the transparent film via an adhesive layer, back surface reflection is reduced, and the antireflection layer is formed. It has been found that changes in reflected light characteristics due to slight variations in refractive index and film thickness can be detected.

In one embodiment of the antireflection film of the present invention, a reflection with a film base material is provided with an antireflection layer on one surface of a transparent film, and a film base material is detachably attached to the other surface through an adhesive layer. It is a prevention film.

An antireflection film with a film substrate is prepared by preparing a laminate in which a film substrate is detachably attached via an adhesive layer on the second main surface of a transparent film (laminate preparation step). It is obtained by forming an antireflection layer comprising two or more thin films on the first main surface of the body transparent film (antireflection layer forming step). In the formation of the antireflection layer, after forming at least one thin film, visible light is irradiated from the first main surface side of the laminate, and the reflected light is detected inline (inline inspection process). The formation of the antireflection layer and the in-line inspection are continuously performed while the laminate is conveyed in one direction. It is preferable that the film forming conditions of the thin film be adjusted according to the detection result of the reflected light in the in-line inspection. Thereby, the reflected light characteristic of an antireflection film can be kept uniform, and the stability of quality can be improved.

The laminate of the film substrate and the adhesive layer preferably has a visible light transmittance of 40% or less. The back surface reflectance of visible light when light is incident on the laminate of the film base material and the adhesive layer from the adhesive layer side is preferably 1.0% or less. By using a light-absorbing film as the film substrate, the back surface reflectance can be reduced. As the film base material, one having a release layer may be used. When a film substrate having a release layer is used, the release layer forming surface is attached to the adhesive layer. In the film substrate, the difference n ₁ −n ₂ between the refractive index n ₁ of the release layer and the refractive index n ₂ of the layer immediately below the release layer is preferably −0.25 to 0.25. Back surface reflection can also be reduced by using a light scattering adhesive as an adhesive layer for temporarily attaching the transparent film and the film substrate.

After forming the antireflection layer on the transparent film, the film substrate is peeled and removed (peeling process). Then, other optical films, such as a polarizing plate, are bonded on the 2nd main surface of a transparent film, and an antireflection film is provided practically.

形成 By forming an antireflection layer on the laminate with reduced back surface reflection, the accuracy of detection of reflected light and the reproducibility of detection in in-line inspection are enhanced. In addition, an antireflection film having excellent uniformity of reflected light characteristics can be obtained by feeding back the detection result of the reflected light in-line to the film forming conditions of the thin film.

It is sectional drawing which shows typically one form of the antireflection film with a film base material. It is sectional drawing which shows an example of a layer structure of a film base material typically. It is a conceptual diagram which shows the structural example of the film-forming apparatus of an antireflection layer. (A) is sectional drawing which shows typically the structural example of the laminated body used for formation of an antireflection film, (B) is an antireflection film with a film base material in which the antireflection layer was formed on the laminated body. It is sectional drawing which shows the example of a structure typically. (C1) and (C2) are cross-sectional views schematically showing a configuration example of the antireflection film after peeling the film substrate. (D1) and (D2) are cross-sectional views schematically showing a configuration example of an antireflection film to which another film is bonded. (A) And (B) is sectional drawing which shows typically the structural example of the polarizing plate with an antireflection layer.

[Configuration of antireflection film]
FIG. 1A is a cross-sectional view schematically showing a configuration of an antireflection film according to one embodiment. The antireflection film 101 in FIG. 1A includes an antireflection layer 50 on the first main surface of the transparent film 10. On the second main surface of the transparent film 10, the film base material 20 is stuck via a bonding layer 30 so as to be peelable. The antireflection layer is a laminate of two or more thin films. In FIG. 1A, an antireflection layer 50 made of a laminate of four thin films 51, 52, 53, 54 is shown.

(Transparent film)
As the transparent film 10, a flexible transparent film is used. The transparent film 10 may have a functional layer (not shown) such as a hard coat layer or an easy adhesion layer on the film surface (antireflection layer forming surface). The hard coat layer can be provided on the surface of the film by a method of forming a cured film of an appropriate ultraviolet curable resin such as acrylic or silicone.

The visible light transmittance of the transparent film is preferably 80% or more, more preferably 90% or more. The thickness of the transparent film 10 is not particularly limited, but a range of about 10 μm to 300 μm is preferable.

Examples of the resin material constituting the transparent film include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polymethyl methacrylate and the like Acrylic polymers; styrene polymers such as polystyrene and acrylonitrile / styrene copolymers; cyclic polyolefins such as polynorbornene; polycarbonates and the like.

The surface of the transparent film is subjected to surface modification treatment such as corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, and treatment with a coupling agent for the purpose of improving adhesion. It may be broken.

(Film substrate)
In the production of the antireflection film, the laminate 40 in which the film substrate 20 is detachably attached to the second main surface (the surface where the antireflection layer 50 is not formed) of the transparent film 10 via the adhesive layer 30. Is used. In this invention, the back surface reflection at the time of entering light from the transparent film side can be reduced by bonding the film base material 20 with the transparent film 10.

The back surface reflectance of visible light when light is incident on the laminate of the film base material and the adhesive layer from the adhesive layer side is preferably 1.0% or less, and 0.7% or less. More preferably, it is more preferably 0.5% or less, and particularly preferably 0.3% or less. The visible light reflectance is measured according to JIS R3106: 1998. As the film substrate 20, a light-absorbing film, a light scattering film having fine irregularities on the surface, or the like is preferably used. In order to further reduce back surface reflection, a light absorbing film is preferably used as the film substrate 20.

The visible light transmittance of the laminate of the film substrate 20 and the adhesive layer 30 is preferably 40% or less, more preferably 20% or less, and even more preferably 10% or less. When a transparent material is used as the adhesive layer 30, the visible light transmittance of the film substrate 20 is preferably 40% or less, more preferably 20% or less, and even more preferably 10% or less. .

When the visible light transmittance of the laminate of the film substrate and the adhesive layer is T (%), and the refractive index of the film substrate is n, the back surface reflectance when the light is incident from the adhesive layer side (of the film substrate) The ratio of light reflected at the air interface and re-emitted from the adhesive layer can be calculated as follows.
Backside reflectance ^{(%) = (T 2/} 100) × (n-1) 2 / (n + 1) 2

If the visible light transmittance T is 40% or less, even when the reflection due to the difference in refractive index at the interface between the film base and air is about 6% (when the refractive index of the film base is about 1.6). The back surface reflectance with respect to incident light from the transparent film side is 1% or less.

The material of the film base 20 is polyester, cellulose polymer, acrylic polymer, styrene polymer, amide polymer, polyolefin, cyclic polyolefin, polycarbonate, or the like. A light-absorbing film substrate can be obtained by adding a black pigment such as carbon black to these resin materials or providing a colored layer of black ink or the like on the surface of the base film. The colored layer may be provided only on one side of the base film, or may be provided on both sides. When a light-absorbing film having a colored layer is used as the film substrate 20, a colored layer is provided on at least the surface of the base film on the transparent film 10 side from the viewpoint of suppressing light reflection at the interface on the transparent film 10 side. It is preferable that The thickness of the colored layer is, for example, about 0.5 μm to 10 μm.

As shown in FIG. 3 (C1) and FIG. 3 (C2), the film substrate 20 is peeled and removed when the antireflection film is put into practical use. That is, the film substrate 20 is a process material that is not included in the final product. Therefore, the film base is preferably as inexpensive as possible, and a general-purpose film such as polyethylene terephthalate is preferably used. The thickness of the film substrate 20 is not particularly limited. If the thickness of the film substrate is small, the continuous film formation length when forming the antireflection layer 50 on the laminate 40 can be increased, and the productivity of the antireflection film can be improved. Therefore, it is preferable that the thickness of the film substrate 20 is as small as possible within a range that does not impair the film formability and handling properties. The thickness of the film substrate is preferably 5 μm to 200 μm, more preferably 10 μm to 130 μm, and even more preferably 15 μm to 110 μm.

FIG. 1B is a cross-sectional view schematically showing an example of the layer configuration of the film base 20. A film substrate 20 shown in FIG. 1B includes a release layer 21 on a base film 25. The release layer 21 can be formed, for example, by applying a release agent to the surface of the base film 25. As the release agent, a release material such as silicone, fluorine, long-chain alkyl, or fatty acid amide, or a solution containing silica powder or the like is used. When a film base material provided with a release layer is used, it is preferable that the release layer 21 is disposed on the adhesive surface with the adhesive layer 30. Since the adhesive force between the transparent film 10 and the film substrate 20 is reduced due to the presence of the release layer on the bonding surface with the adhesive layer, the film substrate from the antireflection film after forming the antireflection layer is reduced. Peeling and removal can be easily performed.

It is preferable that the refractive index difference between the release layer 21 of the film substrate 20 and the layer immediately below the release layer 21 is small. Specifically, the difference n ₁ −n ₂ between the refractive index n ₁ of the release layer 21 and the refractive index n ₂ of the layer immediately below the release layer is preferably −0.3 to 0.25, and −0. More preferably, it is 25 to 0.25, more preferably −0.25 to 0.15, and particularly preferably −0.25 to 0.1. The refractive index is a value at a wavelength of 590 nm. The layer immediately below the release layer is a layer adjacent to the release layer 21. When the release layer 21 is directly formed on the base film 25, the base film 25 corresponds to a layer immediately below the release layer. When a colored layer or an oligomer sealing layer is provided between the base film and the release layer, the layer adjacent to the release layer corresponds to the layer immediately below the release layer. .

For example, when a release layer is provided directly on the PET base film (when the PET base film is a layer immediately below the release layer), the refractive index of the release layer is 1.35 to 1.8. Preferably, 1.4 to 1.75 is more preferable.

Reflected light related to the film substrate when light is incident on the laminate of the antireflection film and the film substrate from the antireflection layer side is mainly the difference in refractive index on the back side (air interface) of the film substrate. The reflected light due to the difference in refractive index at the interface between the release layer and the layer immediately below (such as the base film) may also affect the measurement of the reflectance. By setting the refractive index difference n ₁ -n ₂ at this interface within the above range, the reflectance of the film substrate can be further reduced.

Further, if the difference in refractive index at the interface between the film substrate 20 and the adhesive layer 30 described later is reduced and the reflected light at this interface is reduced, the reflected light with respect to the incident light from the adhesive layer side is further reduced. it can. In order to reduce the refractive index difference at these interfaces, the refractive index n ₁ of the release layer 21 is an intermediate value between the refractive index n ₂ of the layer immediately below it and the refractive index n ₃ of the adhesive layer 30. Preferably there is. That is, it is preferable that n ₂ <n ₁ <n ₃ or n ₃ <n ₁ <n ₂ .

(Adhesive layer)
The transparent film 10 and the film substrate 20 are bonded together via the adhesive layer 30. Although the material of the contact bonding layer 30 is not specifically limited, In order to stick the film base material 20 so that peeling is possible, an adhesive is used preferably. As the pressure-sensitive adhesive, for example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a sea corn pressure-sensitive adhesive, or the like can be used. Among these, an acrylic pressure-sensitive adhesive mainly composed of an acrylic polymer is preferably used.

The adhesive layer 30 may be transparent or opaque. If a light absorptive film is used as the film base material 20 and the light absorptive adhesive layer 30 is used, the visible light transmittance of the laminate of the film base material 20 and the adhesive layer 30 is lowered, and the back surface reflection is further increased. Can be reduced. On the other hand, as shown in FIG. 3 (D1), when the adhesive layer 30 is used for bonding to another film 71 after peeling the film substrate 20 from the antireflection film, a light-transmitting adhesive layer is used. Is preferred. The light-transmitting adhesive layer preferably has a visible light transmittance of 80% or more, more preferably 85% or more, and still more preferably 90% or more.

The adhesive layer 30 may have light scattering properties. By imparting light scattering properties to the adhesive layer, the light transmitted through the transparent film 10 is scattered by the adhesive layer, and the back surface reflection can be further reduced. Examples of the light scattering adhesive layer include a light scattering adhesive in which particles are dispersed in an adhesive. When the adhesive layer is a light scattering pressure-sensitive adhesive, the back surface reflection tends to be reduced as the haze of the light scattering pressure-sensitive adhesive increases. Therefore, the haze of the light scattering pressure-sensitive adhesive layer is preferably 40% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably 90% or more.

Examples of the particles contained in the light scattering adhesive include inorganic fine particles and polymer fine particles. The particles are preferably polymer fine particles. Examples of the material of the polymer fine particles include silicone resin, polymethyl methacrylate resin, polystyrene resin, polyurethane resin, and melamine resin. Since these resins are excellent in dispersibility with respect to the pressure-sensitive adhesive and have an appropriate refractive index difference from the pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a light-scattering pressure-sensitive adhesive layer excellent in diffusion performance can be obtained. The shape of the particle is not particularly limited, and examples thereof include a true spherical shape, a flat shape, and an indefinite shape. The particles may be used alone or in combination of two or more.

The volume average particle diameter of the particles is preferably 1 μm to 10 μm, more preferably 1.5 μm to 5 μm. By setting the volume average particle size in the above range, excellent light scattering performance can be imparted. The volume average particle diameter can be measured using, for example, an ultracentrifugal automatic particle size distribution measuring apparatus. The content of the particles in the light scattering pressure-sensitive adhesive layer is preferably 0.3% by weight to 50% by weight, and more preferably 3% by weight to 48% by weight. By making the compounding quantity of particle | grains into said range, the light-scattering adhesive layer which has the outstanding light-scattering performance is obtained.

(Antireflection layer)
The antireflection layer 50 is formed on the first main surface of the laminate 40 in which the film substrate 20 is bonded to the second main surface of the transparent film 10 via the adhesive layer 30. The antireflection layer 50 is composed of two or more thin films. 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 incident light and reflected light cancel each other. By making the antireflection layer a multilayer laminate of two or more thin films having different refractive indexes, the reflectance can be reduced in the wavelength range of visible light in a wide band.

Examples of the material of the thin film constituting the antireflection layer 50 include metal oxides, nitrides, fluorides, and the like. For example, as a low refractive index material having a refractive index of about 1.35 to 1.55, silicon oxide, magnesium fluoride, etc., as a high refractive material having a refractive index of about 1.80 to 2.40, titanium oxide, niobium oxide, oxide Examples include zirconium, tin-doped indium oxide (ITO), and antimony-doped tin oxide (ATO). Further, in addition to the low refractive index layer and the high refractive index layer, as a middle refractive index layer having a refractive index of about 1.50 to 1.85, for example, titanium oxide or a mixture of the above low refractive index material and high refractive material ( A thin film made of a mixture of titanium oxide and silicon oxide or the like may be formed.

The laminated structure of the antireflection layer 50 is a two-layer structure of a high refractive index layer having an optical film thickness of about 240 nm to 260 nm and a low refractive index layer having an optical film thickness of about 120 nm to 140 nm from the transparent film 10 side; Three-layer configuration of a medium refractive index layer having a thickness of about 170 nm to 180 nm, a high refractive index layer having an optical thickness of about 60 nm to 70 nm, and a low refractive index layer having an optical thickness of about 135 nm to 145 nm; A high refractive index layer having an optical thickness of about 35 nm to 55 nm, a high refractive index layer having an optical thickness of about 80 nm to 240 nm, and a low refractive index layer having an optical thickness of about 120 nm to 150 nm. Four-layer configuration: a low refractive index layer having an optical film thickness of about 15 nm to 30 nm, a high refractive index layer having an optical film thickness of about 20 nm to 40 nm, a low refractive index layer having an optical film thickness of about 20 nm to 40 nm, and light And the film thickness 240 nm ~ 290 nm as high refractive index layer, five-layer configuration of the optical thickness 100 nm ~ 200 nm as low refractive index layer. The range of the refractive index and film thickness of the thin film constituting the antireflection layer is not limited to the above examples. The antireflection layer 50 may be a laminate of six or more thin films.

[Method of forming antireflection layer]
The method for forming the thin film constituting the antireflection layer is not particularly limited, and either a wet coating method or a dry coating method may be used. Dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam vaporization are preferred because a thin film with a uniform thickness can be formed and the adjustment of the film thickness of the nanometer level thin film is easy. And electron beam evaporation are preferred.

The formation of the antireflection layer is carried out continuously while transporting the laminate 40 in one direction. For example, when the antireflection layer is formed by sputtering, continuous film formation is performed using a winding type sputtering apparatus.

After forming at least one thin film constituting the antireflection layer, visible light is irradiated from the first main surface side (thin film forming surface side) of the laminate 40, and the reflected light is detected to perform in-line inspection. To be implemented. By recording the result of the in-line inspection, it is possible to improve the efficiency of the process of bonding the antireflection film and another optical film, forming an image display device, or the like. For example, if the portion determined to be out of specification in the in-line inspection is not supplied to the next process, the yield of the final product can be improved and the rework frequency can be reduced. Further, an antireflection film having excellent uniformity of reflected light characteristics can be obtained by adjusting the film forming conditions of the thin film based on the detection result of the reflected light in-line.

In the following, the case where the antireflection layer 50 including the four thin films 51, 52, 53, and 54 is formed on the transparent film 10 by the sputtering method is taken as an example of the in-line reflected light detection result as the film formation condition. The method for producing the antireflection film will be described while reflecting the results.

FIG. 2 is a conceptual diagram showing a configuration example of a film forming apparatus for reflecting an in-line detection result of reflected light on film forming conditions of the antireflection layer. The film forming apparatus in FIG. 2 includes two film forming rolls 281 and 282. A plurality of film forming chambers 210, 220, 230, and 240 separated by partition walls are provided along the circumferential direction of each film forming roll 281 and 282. A cathode is provided in each film formation chamber, and each cathode 214, 224, 234, 244 is connected to a power source 216, 226, 236, 246. Targets 213, 223, 233, and 243 are disposed on the cathodes 214, 224, 234, and 244 so as to face the film forming rolls 281 and 282. A gas introduction pipe is connected to each of the film forming chambers 210, 220, 230, and 240, and valves 219, 229, 239, and 249 are provided upstream of the gas introduction pipe.

A winding body of the laminate 40 of the transparent film 10 and the film substrate 20 is set on the unwinding roll 251 in the preparation chamber 250. The laminated body 40 unwound from the unwinding roll is conveyed onto the first film forming roll 281 and is sequentially guided to the first film forming chamber 210 and the second film forming chamber 220. In the first film formation chamber 210, the thin film 51 is formed on the first main surface of the transparent film 10, and in the second film formation chamber 220, the thin film 52 is formed on the thin film 51. The laminated body 45 on which the thin films 51 and 52 are formed is conveyed onto the second film forming roll 282, and the thin film 53 and the thin film 54 are sequentially formed in the third film forming chamber 230 and the fourth film forming chamber 240. . The antireflection film 101 in which the antireflection layer 50 composed of four thin films is formed on the transparent film 10 of the laminated body 40 is guided to the winding chamber 260 and wound up by the take-up roll 261. A wound body is obtained.

In the winding chamber 260, a light irradiation unit 291 and a light detection unit 293 are arranged so as to face the surface of the antireflection film 101 where the antireflection layer 50 is formed. The light emitted from the light irradiation unit may be white light or monochromatic light as long as it contains visible light. The light irradiation may be continuous or intermittent. The light detection unit 293 detects the reflected light of the light irradiated to the antireflection film 101 from the light irradiation unit 291. The reflected light detected by the light detection unit 293 is converted into an electric signal by the light receiving element, and calculation is performed by the calculation unit 273 as necessary. In the calculation unit, calculation of the spectrum of the detected reflected light, conversion to a specific color system (for example, XYZ color system, L ^* a ^* b ^* color system, Yab color system) are performed. .

Further, the calculation unit 273 determines the difference between the reflected characteristic of the detected reflected light and the target reflected light characteristic, and changes the film forming condition of the thin film when the difference exceeds a threshold value. In addition, a signal is transmitted to the control unit. The control unit 275 adjusts the film forming conditions of the thin film so that the reflected light characteristics (reflectance, hue, etc.) are within a predetermined range.

Examples of film formation conditions to be adjusted include the amount of gas introduced into the film formation chamber, the film conveyance speed, and the amount of input power. For example, in the film forming apparatus illustrated in FIG. 2, the control unit 275 includes the rotation speed of the unwinding roll 251, the winding roll 261, and the film forming rolls 281 and 282, the input power amount of the power supplies 216, 226, 236, and 246, In addition, by adjusting the opening of the valves 219, 229, 239, and 249 of the gas introduction pipe, the film forming conditions of the thin film in each film forming chamber can be adjusted. The change in the characteristic of the reflected light is mainly caused by the change in the thickness of the thin film. Therefore, it is preferable to adjust the film forming conditions of the thin film so that the film thickness of the thin film approaches the set value. The adjustment of the film forming conditions is executed by PID control, for example. Further, the refractive index can be changed by adjusting the manufacturing conditions so as to change the composition of the thin film. For example, in reactive sputtering, by changing the amount of oxygen introduced into the film formation chamber, the oxygen content in the metal oxide changes, and the refractive index of the thin film changes accordingly.

In order to determine the difference from the target reflected light characteristic, it is necessary to determine the reflected light characteristic as a reference in advance. The reference reflected light characteristics are appropriately determined according to product standards and the like. As an example, there are a method based on the center of the standard range of a product and a method based on a reflected light spectrum calculated by optical calculation from the set film thickness and refractive index of each layer (see the examples described later). The reflected light spectrum of the product measured off-line may be used as a reference.

It is preferable that the calculation or measurement of the reference spectrum of the reflected light in the optical calculation or off-line is performed in a state in which the back surface reflection is excluded. By defining the standard by eliminating the back surface reflection, the target reflected light characteristic can be matched with the product standard, and the difference between the standard value and the in-line measurement result can be accurately evaluated.

The antireflection film 101 after forming all the thin films constituting the antireflection layer 50 on the transparent film 10 of the laminate 40 preferably has a luminance Y in the Yab color system of 0.5% or less. Note that the Y value in the Yab expression system is the same as the Y value in the XYZ expression system. In this invention, the Y value of reflected light can be made small by reducing back surface reflection using the light absorptive film base material 20. FIG. By reducing the reflection Y value, the difference between the reference spectrum and the in-line measurement value can be detected with high sensitivity, and the detection sensitivity for the difference in hue tends to be improved.

In order to keep the product stably within the standard when the back reflection is large and the detection sensitivity is low, the control range of the in-line measurement value is taken into consideration for safety in consideration of the difference that may occur between the in-line measurement value and the true value. Need to be narrowed. For this reason, the control range of manufacturing conditions is narrowed, and it may be difficult to adjust the film forming conditions of the thin film. In addition, due to the narrow management width of in-line measurement, the number of products that are originally within the standard is judged to be out of the standard, and the product yield tends to decrease.

On the other hand, according to the present invention, by suppressing back surface reflection, the detection sensitivity of the difference between the reference value and the in-line measurement value can be increased, and the management range in the manufacturing process can be expanded. Therefore, in addition to facilitating process management based on in-line measurement results, the yield of products can be improved.

Further, by suppressing back surface reflection and reducing the reflection Y value, the difference in chromaticity from the reference spectrum tends to be reduced. Therefore, it becomes easy to manage the in-line hue. The chromaticity difference Δab between the reflected light of the antireflection film 101 after forming all the thin films constituting the antireflection layer 50 on the transparent film 10 of the laminate 40 and the reference spectrum of the antireflection film excluding the back surface reflection is 7.5 or less is preferable. The chromaticity difference Δab is a distance on the ab chromaticity diagram of the Yab color system, and is calculated from the chromaticities a ₀ and b _{0 of} the reference spectrum and the chromaticities a and b of the measurement target by the following formula. .
Δab = {(a−a ₀ ) ² + (b−b ₀ ) ² } ^1/2

As described above, the form in which the in-line detection of the reflected light is performed after the formation of all the thin films 51, 52, 53, 54 has been described. It may be performed at any stage. For example, after the thin films 51 and 52 are formed on the first film-forming roll 281, the light-irradiating unit 297 irradiates the laminated body 45 until the laminated body 45 is guided onto the second film-forming roll 282. Inline detection of the reflected light may be performed by detecting the reflected light of the light by the light detection unit 299. Further, inline detection of reflected light may be performed at two or more locations. For example, in the embodiment shown in FIG. 2, after the two layers of thin films 51 and 52 are formed, the light detection unit 299 detects the reflected light from the laminate 45, and further forms the two layers of thin films 53 and 54 thereon. The light detection unit 293 may detect the reflected light from the antireflection film 101 later. If in-line measurement is performed at two or more places as described above, it is easy to determine a film formation chamber whose film formation conditions are to be adjusted, and finer control is possible. Furthermore, in-line detection may be performed at a plurality of positions in the width direction, and film formation conditions may be adjusted so that reflected light characteristics in the width direction are uniform. For example, the film forming conditions in the width direction can be adjusted by changing the gas introduction amount in the width direction.

FIG. 2 shows an example in which the antireflection layer 50 is composed of four thin films. However, as described above, the number of thin films constituting the antireflection layer is not particularly limited as long as it is two or more. An appropriate film forming apparatus can be used depending on the number of thin films. The number of film forming chambers provided around one film forming roll may be one, or three or more. The number of film forming rolls may be one, or three or more.

As described above, the thin film forming method is not limited to the sputtering method, and various dry coating methods and wet coating methods may be employed. Even when the thin film is formed by a method other than sputtering, an antireflection film having excellent uniformity of reflected light characteristics can be obtained by adjusting the formation conditions of the thin film based on the in-line detection result of the reflected light.

When light is applied to the antireflection film in which the antireflection layer is formed on the first main surface of the transparent film, most of the reflected light is due to the back surface reflection on the second main surface side. It is difficult to accurately detect the reflected light on the main surface side (antireflection layer forming surface). On the other hand, back surface reflection is suppressed by sticking the light absorptive film base material 20 to the second main surface side of the transparent film 10. In this embodiment, since most of the reflected light detected by the light detection unit 293 is reflected light from the first main surface side (antireflection layer forming surface side), the reflected light from the first main surface side. Slight changes in characteristics can be detected inline. By adjusting the film forming conditions of the thin film based on the detection result, an antireflection film having excellent uniformity of reflected light characteristics can be manufactured.

In this way, before forming the antireflection layer to be inspected, by sticking a light-absorbing film base material to the transparent film, the back surface reflection is suppressed and the reflected light characteristics are accurately measured in-line. it can. When an antireflection layer is formed by vacuum film formation such as sputtering, it is impossible to inspect the product by extracting it during film formation, and it is impossible to bond and peel the film on the same line as the film formation line. Therefore, the method of the present invention is particularly useful.

As described above, since an inexpensive general-purpose film is used as the film base 20, the laminate of the transparent film and the film base is cheaper than the polarizing plate. Therefore, compared to the case where a polarizing plate is used as in Patent Document 1, even if a non-standard part occurs at the initial stage of the formation of the antireflection layer (before the start of film formation condition control by inline reflected light detection), the process loss Has little impact on manufacturing costs.

In addition, by forming the antireflection layer on the laminate 40 of the transparent film 10 and the film base material 20, the continuous film formation length of the antireflection layer as compared with the case of forming the antireflection layer on the polarizing plate. Can be increased. In general, for the unwinding roll 251 and the winding roll 261, the upper limit of the weight and diameter of the film winding body that can be set on the mount is determined. The smaller the film thickness, the larger the length of the film in which the weight and diameter of the wound body reach the specified upper limit, and thus the continuous film forming length increases. In general, the polarizing plate has a configuration in which a transparent protective film is provided on both sides of a polarizer and is composed of three films, whereas the laminate 40 can be composed of two films. . Therefore, the laminate 40 can be designed to have a smaller thickness than the polarizing plate, and the continuous film formation length can be increased. As a result, the operation rate of the film forming apparatus can be improved and productivity can be increased.

[Practical form of antireflection film]
In this invention, the laminated body (FIG. 3 (A)) by which the film base material 20 was affixed on the 2nd main surface side of the transparent film 10 was used in order to measure the reflected light characteristic of an antireflection film in-line. It is done. After the antireflection layer 50 is formed on the transparent film 10 (FIG. 3 (B)) and the measurement of the reflected light characteristics of the antireflection film 101 with a film substrate is performed, the film substrate 20 becomes unnecessary. . Therefore, when the antireflection film is put to practical use, the film substrate 20 is preferably peeled off from the transparent film 10.

When the film substrate is peeled and removed, for example, as shown in FIG. 3 (C1), only the film substrate 20 is peeled and removed with the adhesive layer 30 attached to the transparent film 10. For example, as shown in FIG. 1B, if a film base 20 having a release layer 21 on the adhesive layer forming surface side of the base film 25 is used, the film base 20 remains with the adhesive layer 30 left on the transparent film 10. Can only peel. After removing the film substrate, another film 71 is bonded to the second main surface of the transparent film 10 via the adhesive layer 30.

When removing the film base material, the adhesive layer 30 may be peeled off from the transparent film 10 together with the film base material 20 as shown in FIG. After removing the film substrate, another film 72 is bonded to the second main surface of the transparent film 10 via another adhesive layer 33.

As described above, the film substrate 20 is provided to improve the detection accuracy of the reflected light characteristics in-line after the formation of the antireflection layer or after the formation of the antireflection layer, and is peeled off after completion of the inspection. The In both cases where only the film substrate 20 is peeled while leaving the adhesive layer 30 on the transparent film 10, and when the adhesive layer 30 is peeled from the transparent film 10 together with the film substrate 20, the film substrate is peeled and removed. The later antireflection film is put to practical use by being bonded to another film. In order to increase the working efficiency of the bonding between the antireflection film and another film, it is preferable that the bonding is performed inline using a roll laminator or the like. Therefore, it is preferable that the peeling operation of the film substrate 20 performed between the in-line inspection of the reflected light characteristic and the bonding with another film is also performed in-line.

In order to stably carry out peeling removal of the film substrate 20 from the transparent film 10 after the formation of the antireflection layer 50 in a stable manner, it is preferable that the peeling force of the film substrate 20 from the transparent film 10 is small. Specifically, the peel force in a 180 ° peel test (peel rate: 10 m / min) between the transparent film and the film substrate is preferably 2 N / 50 mm or less, more preferably 1.5 N / 50 mm or less, and 1 N / 50 mm. The following is more preferable. The peel force can be reduced by adjusting the composition of the adhesive layer 30 or providing a release layer on the surface of the film substrate.

The films 71 and 72 to be bonded to the second main surface of the transparent film 10 after the film substrate 20 is peeled are not particularly limited, and a transparent release film or the like may be bonded. For example, when shipping an antireflection film provided with an antireflection layer on a transparent film as a product, the light-absorbing film substrate 20 used at the time of forming the antireflection layer is replaced with a transparent release film. In addition, it is possible to measure transmittance and inspect for the presence or absence of contamination. Moreover, the designability of a product is improved by using a transparent release film.

In practical use of the antireflection film, an optical film is bonded to the second main surface of the transparent film 10. Examples of the optical film include a polarizer, a polarizer protective film, an optical compensation film (retardation film), and combinations thereof. As an example of a practical form, a polarizing plate with an antireflection layer is obtained by laminating an antireflection film and an optical film containing a polarizer. As described above, in the form in which the antireflection layer is formed on the transparent film and then bonded to the polarizer or the like, without exposing the polarizer to a high temperature environment or high output plasma for forming the antireflection layer, A polarizing plate with an antireflection layer is obtained. Therefore, it is possible to suppress defects such as the deterioration of the polarizer and increase the yield.

4A and 4B are cross-sectional views schematically showing a configuration example of a polarizing plate with an antireflection layer. In the polarizing plate 121 with an antireflection layer shown in FIG. 4A, one surface of a polarizer 79 is bonded to the second main surface of the transparent film 10 with an adhesive layer 36 interposed therebetween. A transparent protective film 74 is bonded to the other surface of the polarizer 79 via an adhesive layer 38, and the release film 22 is temporarily attached to the surface of the transparent protective film 74 via an adhesive layer 39. ing.

The polarizer 79 includes a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film, and a dichroic substance such as iodine or a dichroic dye. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products.

Among them, from the viewpoint of having a high degree of polarization, a dichroic substance such as iodine or a dichroic dye is adsorbed on a polyvinyl alcohol film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in a predetermined direction. A polyvinyl alcohol (PVA) polarizer is preferred. For example, a PVA polarizer can be obtained by subjecting a polyvinyl alcohol film to iodine staining and stretching. As the PVA polarizer, a thin polarizer having a thickness of 10 μm or less can be used. Thin polarizers are described in, for example, JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917, Patent No. 4691205, Patent No. 4751481, and the like. And a thin polarizing film. Such a thin polarizer is obtained, for example, by a production method including a step of stretching a PVA-based resin layer and a stretching resin base material in the state of a laminate, and a step of iodine staining.

As the transparent protective film 74, materials similar to those described above as the material of the transparent film 10 are preferably used. Note that the material of the transparent protective film 74 and the material of the transparent film 10 may be the same or different.

Adhesives used for the adhesive layers 36 and 38 include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl alcohols, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, and fluorine-based adhesives. What uses a polymer, a rubber-type polymer, etc. as a base polymer can be selected suitably, and can be used. For the bonding of the PVA polarizer, a polyvinyl alcohol-based adhesive is preferably used.

In the form shown in FIG. 4B, the polarizing plate in which the transparent protective films 73 and 74 are bonded to both surfaces of the polarizer 79 via the adhesive layers 36 and 38 and the antireflection film are provided via the adhesive layer 35. It is the polarizing plate 122 with an antireflection layer bonded together. The release film 22 is temporarily attached to the surface of the transparent protective film 74 via an adhesive layer 39.

As the adhesive layer 35 used for laminating the transparent protective film 73 and the transparent film 10, an adhesive such as an acrylic adhesive, a rubber adhesive, and a seacorn adhesive is preferable. The adhesive layer 30 (pressure-sensitive adhesive) used for temporary attachment between the transparent film 10 and the film substrate 20 can also be used as it is (see FIGS. 3B and 3).

The antireflection film is preferably used for forming an image display device. When the antireflection film is attached to the outermost surface of the image display device, it is likely to receive contamination (fingerprints, hand dust, dust, etc.) from the external environment. For the purpose of preventing contamination from such external environment and imparting easy removal of contamination, an antifouling layer comprising a fluorine group-containing silane compound or a fluorine group-containing organic compound is provided on the surface of the antireflection layer. It may be provided.

[Evaluation of reflected light characteristics by optical simulation]
In the following examples and comparative examples, the spectrum of reflected light of a laminate in which various film substrates are bonded to each other on the side opposite to the antireflection layer forming surface of the antireflection film is calculated by optical simulation. did. As an antireflection film, an acrylic hard coat layer (refractive index 1.51) having a thickness of 8 μm is provided on the surface of a triacetyl cellulose (TAC) film (refractive index 1.49) having a thickness of 80 μm. In addition, a titanium oxide layer having a thickness of 12 nm (refractive index 2.35), a silicon oxide layer having a thickness of 28 nm (refractive index 1.46), a titanium oxide layer having a thickness of 100 nm (refractive index 2.35), and a film thickness A configuration including an antireflection layer composed of four layers of an 85 nm silicon oxide layer (refractive index: 1.46) was adopted.

<Example 1>
A 38 μm-thick black film (with a visible light transmittance of 3% and a refractive index of 1.65) is pasted on the antireflection layer-unformed surface side of the antireflection film via an adhesive layer (refractive index of 1.48) with a thickness of 20 μm. Combined configuration.

<Example 2>
The release layer side of a 38 μm thick black film (visible light transmittance 3%, refractive index 1.65) having an 80 nm silicone release layer (refractive index 1.46) on the surface is a 20 μm thick adhesive layer (refractive The structure which bonded together to the anti-reflective layer non-formation surface of an anti-reflective film via rate 1.48).

<Comparative Example 1>
Instead of the black film of Example 1, a configuration using a black translucent film having a visible light transmittance of 50%.

<Evaluation>
For each configuration of the example and the comparative example, the reflected light spectrum when white light was incident from the antireflection layer side was calculated. Moreover, the reflected light spectrum (reference | standard spectrum) of the antireflection film when back surface reflection was set to zero was calculated. The brightness Y (%) in the Yab color system and the chromaticities a and b were calculated from the obtained reflection spectrum, and the chromaticity difference Δab between the reflected light of each example and comparative example and the reference spectrum was obtained. . Table 1 shows the laminated structure of the transparent film, the adhesive layer, and the film substrate, and the reflected light characteristics in Examples and Comparative Examples.

[Evaluation of peel strength and in-line peelability]
Below, the sample for evaluation was created by bonding a film substrate to a TAC film having a thickness of 80 μm (manufactured by Fuji Film; Fujitac TD80UL) via an adhesive layer, and the peel strength was evaluated.

<Sample 1>
Using a roll laminator, a protective film material (manufactured by Nitto Denko; E-MASK RP300) in which a light-peeling adhesive layer having a thickness of 20 μm was formed on a PET film having a thickness of 38 μm was bonded to the TAC film.

<Sample 2>
Similar to the preparation of Sample 1, after a protective film material was bonded onto the TAC film, a heat treatment was performed at 100 ° C. for 2 hours.

<Sample 3>
Using a roll laminator, a transparent adhesive sheet having a thickness of 20 μm (an acrylic adhesive sheet for polarizing plate made by Nitto Denko) is bonded on a TAC film, and a PET film having a thickness of 38 μm whose surface has been subjected to mold release treatment ( The release treatment surface of Mitsubishi Plastics; Diafoil MRF38) was bonded.

<Evaluation>
Sample 1 and sample 2 were subjected to a peel test at the interface between the TAC film and the adhesive layer, and sample 3 was subjected to a peel test at the interface between the PET film and the adhesive layer.
(Peel test)
Samples 1 to 3 were cut into strips each having a width of 50 mm, and the peel force was measured by a 180 ° peel test (test speed: 10 m / min).
(Inline peelability test)
Using a roll laminator, the in-line peelability of the film substrates of Samples 1 to 3 was evaluated, and those that could be peeled without problems were “good” and those that had abnormal tension during film running were judged “bad”. did.
The results are shown in Table 2.

As shown in Table 1, by reducing the transmittance of the film base material, the back surface reflectance is reduced, and as a result, the Y value of the reflected light is reduced, and the chromaticity difference Δab from the reference spectrum is also reduced. It turns out that it becomes small. In Example 2 in which a film substrate having a release layer on the base film was used, the Y value and the chromaticity difference tend to increase as compared to Example 1 due to an increase in the reflective interface. Back surface reflection can be reduced by adjusting the refractive index of the release layer.

As shown in Table 2, in-line peeling tends to be facilitated by reducing the peeling force between the transparent film and the film substrate. From this result, if the peel strength is reduced by using a light-peelable adhesive material as the material of the adhesive layer or by using a film base material having a release layer, the film base material can be changed after the antireflection layer is formed. It can be seen that the workability at the time of attaching to the film can be improved and the productivity can be improved.

DESCRIPTION OF SYMBOLS 10 Transparent film 20 Film base material 21 Release layer 25 Base film 30, 33, 35, 36, 38, 39 Adhesive layer 40 Laminate 50 Antireflection layer 51, 52, 53, 54 Thin film 73, 74 Transparent protective film 79 Polarization Child 100, 101, 103 Antireflection film 111, 112 Antireflection film (optical film with antireflection layer)
121,122 Antireflection film (polarizing plate with antireflection layer)

Claims (17)

A method for producing an antireflection film comprising an antireflection layer on the first main surface of a transparent film,
A laminated body preparation step of preparing a laminated body in which a film base material is detachably attached to the second main surface of the transparent film via an adhesive layer;
An antireflection layer forming step of forming an antireflection layer comprising two or more thin films on the first main surface of the transparent film of the laminate; and at least one thin film constituting the antireflection layer. After the film, has an in-line inspection process of irradiating visible light from the thin film forming surface side and detecting the reflected light,
The laminate of the film substrate and the adhesive layer has a visible light transmittance of 40% or less,
The method for producing an antireflection film, wherein the antireflection layer forming step and the inline inspection step are continuously performed while the laminate is conveyed in one direction. 2. The reflection according to claim 1, wherein in the in-line inspection process, after all the plurality of thin films constituting the antireflection layer are formed, visible light is irradiated from the formation surface side of the thin film and the reflected light is detected. The manufacturing method of a prevention film. The method for producing an antireflection film according to claim 1 or 2, wherein a film forming condition of the thin film in the antireflection layer forming step is adjusted according to a detection result of reflected light in the inline inspection step. The method for producing an antireflection film according to any one of claims 1 to 3, wherein the film substrate includes a release layer on a contact surface side with the adhesive layer. The film substrate has a difference n ₁ -n ₂ between a refractive index n ₁ of the release layer and a refractive index n ₂ of a layer immediately below the release layer of −0.25 to 0.25. The manufacturing method of the antireflection film according to claim 4. The back surface reflectance of visible light when light is incident on the laminate of the film base material and the adhesive layer from the adhesive layer side is 1.0% or less. The manufacturing method of the antireflection film as described in 1 .. The method for producing an antireflection film according to any one of claims 1 to 6, wherein the adhesive layer is a pressure-sensitive adhesive layer. The method for producing an antireflection film according to claim 7, wherein the pressure-sensitive adhesive layer is a light-scattering pressure-sensitive adhesive layer having a haze of 50% or more. The method for producing an antireflection film according to any one of claims 1 to 8, wherein a peel force in a 180 ° peel test between the transparent film and the film substrate is 2 N / 50 mm or less. 10. The method for producing an antireflection film according to claim 1, further comprising a peeling step in which the film substrate is peeled from the transparent film after the in-line inspection step. The method for producing an antireflection film according to claim 10, wherein, in the peeling step, the film substrate is peeled in a state where the adhesive layer is attached to the transparent film. The method for producing an antireflection film according to claim 10, wherein in the peeling step, the adhesive layer is peeled from the transparent film together with the film base material. The method for producing an antireflection film according to any one of claims 10 to 12, wherein a transparent release film is detachably attached to the second main surface of the transparent film after the peeling step. The method for producing an antireflection film according to any one of claims 10 to 13, wherein an optical film is bonded onto the second main surface of the transparent film after the peeling step. The method for producing an antireflection film according to claim 14, wherein the optical film is an optical film including a polarizer. An antireflection layer is provided on one surface of the transparent film, and a film base material is detachably attached to the second main surface of the transparent film via an adhesive layer.
The laminate of the film base material and the adhesive layer is an antireflection film having a visible light transmittance of 40% or less. A method for measuring the reflected light characteristics of an antireflection film comprising an antireflection layer comprising two or more thin films on the first main surface of the transparent film,
On the second main surface of the transparent film, the reflected light of the visible light irradiated from the first main surface side is detected in a state where the film substrate is detachably attached via the adhesive layer. ,
The laminate of the film substrate and the adhesive layer has a visible light transmittance of 40% or less,
The detection of the reflected light is continuously performed while the antireflection film is conveyed in one direction, and the reflected light characteristic is measured.

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