JP2020057005A - Antireflection film and method for manufacturing the same, and method for measuring reflected light characteristics of antireflection film - Google Patents

Abstract

To provide a method for inspecting an antireflection film, and an antireflection film with excellent uniformity.SOLUTION: A method according to the invention comprises : a laminate preparing step of preparing a laminate (40) in which film base material (20) is peelably stuck onto a second principal surface of a transparent film (10) via an adhesion layer (30); an antireflection layer forming step of forming an antireflection layer (50) composed of a thin film of not less than two layers on a first principal surface of the transparent film; and an in-line inspecting step of emitting visible light from the first principal surface of the laminate after depositing at least one layer of the thin film constituting the antireflection layer, and detecting the reflected light of the visible light. A laminated body of the film base material (20) and the adhesion layer (30) has visible light transmittance of not more than 3%. The method continuously performs the antireflection layer forming step and the in-line inspecting step while transferring the laminate (40) in one direction. Thin film deposition conditions in the antireflection layer forming step are preferably adjusted according to detection results of the in-line inspecting step.SELECTED DRAWING: Figure 1A

Description

  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 the 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 image quality deterioration due to reflection of external light and reflection of an image, improvement of contrast, and the like. The anti-reflection film includes an anti-reflection layer formed of a laminate of a plurality of thin films having different refractive indexes on a transparent film.

  As an embodiment of the antireflection film, a polarizing plate with an antireflection layer can be given. The polarizing plate with an anti-reflection layer is formed by bonding an anti-reflection film to the surface of a polarizing plate or by bonding an anti-reflection film as a protective film to the surface of a polarizer. 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 anti-reflection layer reduces the reflectance of visible light by utilizing multiple reflection interference of a thin film. Therefore, if the refractive index or the film thickness of the thin film changes, the reflected light characteristics such as the reflectance and the reflected light hue change. In the formation of the anti-reflection layer, even if the film forming conditions of the thin film are strictly controlled and kept constant, the film thickness of the thin film and the The refractive index and the like slightly fluctuate. The influence of such a slight variation on the reflected light characteristics is small. Therefore, in general, quality control of an antireflection film is performed by forming a film under a certain condition, and confirming the reflected light characteristics visually with an inspection device such as a spectrophotometer or the like after the film is formed offline. .

  In recent years, as the definition of a display has been advanced, the required characteristics of an antireflection film have been increased, and an antireflection film having lower reflectance and less coloring of reflected light has been demanded. Attempts have also been made to neutralize the light emitted from the panel by adjusting the hue of the reflected light. For example, when the light emitted from the panel has a yellow tint, neutralization is performed by using an anti-reflection film whose reflected light has a bluish tint.

  With the increase of such required characteristics, it has been required to more strictly control the reflected light characteristics of the antireflection film. For this reason, a change in the reflected light characteristic caused by a slight change in the manufacturing conditions may cause the antireflection film to be out of the quality standard. Therefore, in the manufacturing process of the antireflection film, it is necessary to control the film formation conditions more strictly, suppress the fluctuation of the refractive index and the thickness of the thin film, and keep the reflected light characteristics constant.

  In film production, in-line measurement is performed during the production process, and the measurement result is fed back to a previous process to maintain a constant film quality. However, the thickness of the thin film constituting the antireflection layer is several nm to several tens 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 in the middle of a process, the cut-out product is inspected off-line, and the result is fed back to the manufacturing process. However, a thin film such as an anti-reflection layer is formed by a vacuum process such as sputtering, vacuum deposition, or CVD, so that a product cannot be sampled at the start of a line or during a process.

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

  In general, the antireflection film is designed so that the visible light reflectance of the surface on which the antireflection layer is formed is 1% or less, whereas the antireflection film is visible on the back surface 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 anti-reflection 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 the film traveling in the air or in a vacuum with light, it is not easy to eliminate back surface reflection. When back reflection is involved, most of the reflected light detected by the in-line inspection is reflected from the back surface, and is detected even if the characteristics (reflection hue, etc.) of the reflected light from the surface on which the anti-reflection layer is formed change. The reflected light hardly changes. Therefore, it is not easy to accurately measure the characteristics of the reflected light from the anti-reflection layer forming surface side in-line.

  Patent Document 1 proposes a method of measuring the reflectance by disposing 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. I have. If the polarizing plate with an anti-reflection layer and the analyzer are arranged so that the absorption axis directions of both are orthogonal to each other, the reflected light on the back side of the polarizing plate with an anti-reflection layer is absorbed by the analyzer. The reflected light characteristic on the surface side can be measured by eliminating the influence of.

  However, this method cannot be applied except when an antireflection layer is formed on a polarizing plate. The polarizing plate has a configuration in which a transparent film is laminated on both surfaces of a polarizer, and is more expensive than a single transparent film. Therefore, in the method of forming the anti-reflection layer on the polarizing plate, when an out-of-specification portion occurs at the initial stage of the formation of the anti-reflection layer (before the control of the film formation conditions by in-line reflected light detection is started) or the like, the production due to the process loss occurs. The increase in cost tends to be remarkable. Further, the characteristics of the polarizing plate may be deteriorated due to the environment in which the antireflection layer is formed. For example, when a polarizer 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, in forming an anti-reflection layer on a transparent film not containing a polarizer, a method of accurately measuring the reflected light characteristic without the influence of the back surface reflection is required. ing. The present invention provides a method of detecting a change in reflected light characteristics more accurately in-line in a process of forming an antireflection layer on a transparent film, and reflecting the result of the detection in film forming conditions, thereby achieving reflection with excellent uniformity. The purpose is to obtain a prevention film. Another object of the present invention is to provide a method for measuring the reflected light characteristics of an antireflection film in-line.

  In view of the above, as a result of the examination, the use of a laminate in which a light-absorbing film substrate is releasably adhered to the back surface side of the transparent film via an adhesive layer reduces back surface reflection, and the anti-reflection layer It has been found that a change in the reflected light characteristic caused by a slight change in the refractive index, the film thickness, or the like can be detected.

  One embodiment of the antireflection film of the present invention is a reflection film with a film substrate, which is provided with an antireflection layer on one surface of a transparent film, and a film substrate is removably attached to the other surface via an adhesive layer. It is a prevention film.

  The antireflection film with a film substrate is prepared by preparing a laminate in which a film substrate is releasably adhered to the second main surface of a transparent film via an adhesive layer (laminate preparation step). It is obtained by forming an antireflection layer composed of two or more thin films on the first main surface of the transparent film of the body (antireflection layer forming step). In forming the anti-reflection layer, after forming at least one layer of the thin film, visible light is irradiated from the first main surface side of the laminate, and the reflected light is detected in-line (in-line inspection step). The formation of the anti-reflection layer and the in-line inspection are continuously performed while transporting the laminate in one direction. It is preferable that the conditions for forming the thin film be adjusted in accordance with the result of detecting the reflected light in the in-line inspection. Thereby, the reflected light characteristics of the 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 3% or less. It is preferable that the visible light back surface reflectance when light is incident on the laminate of the film substrate and the adhesive layer from the adhesive layer side is 1.0% or less. By using a light-absorbing film as the film substrate, the back surface reflectance can be reduced. What has a release layer may be used as a film base material. 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 2} of the layer immediately below the refractive index _{n 1} and the release layer of the release layer is preferably -0.25～0.25. By using a light-scattering pressure-sensitive adhesive as an adhesive layer for temporarily attaching the transparent film and the film substrate, backside reflection can also be reduced.

  After forming the antireflection layer on the transparent film, the film substrate is peeled off (peeling step). Thereafter, another optical film such as a polarizing plate is bonded on the second main surface of the transparent film, and the antireflection film is put to practical use.

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

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 the layer structure of a film base material typically. It is a conceptual diagram which shows the example of a structure of the film-forming apparatus of an antireflection layer. (A) is a sectional view schematically showing a configuration example of a laminate used for forming an anti-reflection film, and (B) is an anti-reflection film with a film substrate having an anti-reflection layer formed on the laminate. 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 an antireflection film after a film substrate is peeled off. (D1) and (D2) are cross-sectional views schematically showing configuration examples of an antireflection film to which another film is attached. (A) and (B) are sectional views schematically showing a configuration example of a polarizing plate with an antireflection layer.

[Configuration of antireflection film]
FIG. 1A is a cross-sectional view schematically illustrating a configuration of an antireflection film according to one embodiment. The anti-reflection film 101 of FIG. 1A includes an anti-reflection layer 50 on the first main surface of the transparent film 10. On the second main surface of the transparent film 10, a film substrate 20 is releasably attached via an adhesive layer 30. The antireflection layer is a laminate of two or more thin films. FIG. 1A shows an anti-reflection layer 50 composed of a laminate of four thin films 51, 52, 53, 54.

(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 easily adhesive layer on the film surface (the surface on which the antireflection layer is formed). The hard coat layer can be provided by a method of forming a cured film of an appropriate ultraviolet curable resin such as an acrylic or silicone resin on the surface of the film.

  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 is preferably in the range of about 10 μm to 300 μm.

  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-based polymers such as polystyrene and acrylonitrile-styrene copolymer; cyclic polyolefins such as polynorbornene; and polycarbonate.

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

(Film substrate)
In the production of the anti-reflection film, the laminate 40 in which the film substrate 20 is peelably adhered to the second main surface (the surface on which the anti-reflection layer 50 is not formed) of the transparent film 10 via the adhesive layer 30. Is used. In the present invention, by bonding the film substrate 20 to the transparent film 10, the backside reflection when light is incident from the transparent film side can be reduced.

  When light is incident on the laminate of the film substrate and the adhesive layer from the adhesive layer side, the visible light back surface reflectance is preferably 1.0% or less, and is preferably 0.7% or less. It is more preferably 0.5% or less, further 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. .

Assuming that 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 rear surface reflectance (light of the film substrate) when light is incident from the adhesive layer side 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 the 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 reflectance of the back surface with respect to the incident light from the transparent film side is 1% or less.

  As the material of the film substrate 20, polyesters, cellulose polymers, acrylic polymers, styrene polymers, amide polymers, polyolefins, cyclic polyolefins, polycarbonates, and the like are used. 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 coloring layer may be provided on only one surface of the base film, or may be provided on both surfaces. When a light-absorbing film having a colored layer is used as the film substrate 20, from the viewpoint of suppressing light reflection at the interface on the transparent film 10 side, a colored layer is provided on at least the surface of the base film on the transparent film 10 side. Preferably. The thickness of the coloring layer is, for example, about 0.5 μm to 10 μm.

  As shown in FIGS. 3 (C1) and 3 (C2), the film substrate 20 is peeled off when the antireflection film is put to practical use. That is, the film substrate 20 is a process material not included in the final product. Therefore, the film substrate 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 be as small as possible, as long as the film formability and handleability are not impaired. The thickness of the film substrate is preferably 5 μm to 200 μm, more preferably 10 μm to 130 μm, and still more preferably 15 μm to 110 μm.

  FIG. 1B is a cross-sectional view schematically illustrating an example of the layer configuration of the film substrate 20. The 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 a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agent, or a solution containing silica powder or the like is used. When a film substrate having a release layer is used, it is preferable that the release layer 21 be disposed on the surface to be bonded to the adhesive layer 30. Since the adhesive force between the transparent film 10 and the film substrate 20 is reduced by the presence of the release layer on the surface to be bonded to the adhesive layer, the film substrate from the antireflection film after the formation of the antireflection layer is reduced. Peeling and removal can be easily performed.

It is preferable that the difference in the refractive index 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 −0.1 to 0.25. 25 to 0.25 is more preferable, -0.25 to 0.15 is further preferable, and -0.25 to 0.1 is particularly preferable. 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 formed directly on the base film 25, the base film 25 corresponds to a layer immediately below the release layer. When a colored layer, an oligomer sealing layer, or the like is provided between the base film and the release layer, a layer adjacent to the release layer among these layers corresponds to a layer immediately below the release layer. .

  For example, when a release layer is provided directly on a 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.

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

In addition, if the difference in the refractive index at the interface between the film base material 20 and the adhesive layer 30 described below is reduced to reduce the reflected light at this interface, the reflected light with respect to the incident light from the adhesive layer side is further reduced. it can. In order to reduce the difference in the refractive index at these interfaces, the refractive index n ₁ of the release layer 21 is a value intermediate between the refractive index n ₂ of the layer immediately below 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 via an adhesive layer 30. The material of the adhesive layer 30 is not particularly limited, but an adhesive is preferably used in order to peelably attach the film substrate 20. As the pressure-sensitive adhesive, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a sea cone-based pressure-sensitive adhesive, or the like can be used. Among them, an acrylic pressure-sensitive adhesive containing an acrylic polymer as a main component is preferably used.

  The adhesive layer 30 may be transparent or opaque. If a light-absorbing film is used as the film substrate 20 and the light-absorbing adhesive layer 30 is used, the visible light transmittance of the laminate of the film substrate 20 and the adhesive layer 30 is reduced, and the backside reflection is further reduced. 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 even more preferably 90% or more.

  The adhesive layer 30 may have a light scattering property. By making the adhesive layer have a light scattering property, the light transmitted through the transparent film 10 is scattered by the adhesive layer, and the backside reflection can be further reduced. Examples of the adhesive layer having light scattering properties 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 larger the haze of the light-scattering pressure-sensitive adhesive, the lower the rear surface reflection tends to be. Therefore, the haze of the light-scattering pressure-sensitive adhesive layer is preferably at least 40%, more preferably at least 50%, further preferably at least 70%, particularly preferably at least 90%.

  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 in an adhesive and have an appropriate refractive index difference from an adhesive such as an acrylic adhesive, a light scattering adhesive layer having excellent diffusion performance can be obtained. The shape of the particles is not particularly limited, and examples thereof include a true sphere, a flat shape, and an irregular 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, and 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 provided. The volume average particle size can be measured, for example, using an ultracentrifugal automatic particle size distribution analyzer. The content of the particles in the light-scattering pressure-sensitive adhesive layer is preferably from 0.3% by weight to 50% by weight, and more preferably from 3% by weight to 48% by weight. By setting the amount of the particles in the above range, a light-scattering pressure-sensitive adhesive layer having excellent light-scattering performance can be obtained.

(Anti-reflective layer)
An anti-reflection layer 50 is formed on the first main surface of the laminate 40 in which the film substrate 20 is adhered to the second main surface of the transparent film 10 with the adhesive layer 30 interposed therebetween. The antireflection layer 50 is composed of two or more thin films. In general, the anti-reflection layer is adjusted in optical thickness (product of refractive index and thickness) of a thin film such that inverted phases of incident light and reflected light cancel each other. By forming the antireflection layer as a multilayer laminate of two or more thin films having different refractive indexes, the reflectance can be reduced in a wide wavelength range of visible light.

  Examples of the material of the thin film forming the antireflection layer 50 include metal oxides, nitrides, and fluorides. For example, as a low refractive index material having a refractive index of about 1.35 to 1.55, silicon oxide, magnesium fluoride, or the like, and as a high refractive material having a refractive index of about 1.80 to 2.40, titanium oxide, niobium oxide, or oxidized oxide is used. Examples include zirconium, tin-doped indium oxide (ITO), and antimony-doped tin oxide (ATO). In addition to the low refractive index layer and the high refractive index layer, as a medium 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 ( Or a mixture of titanium oxide and silicon oxide).

  The laminated structure of the antireflection layer 50 includes, from the transparent film 10 side, a two-layer structure of a high refractive index layer having an optical thickness of about 240 nm to 260 nm and a low refractive index layer having an optical thickness of about 120 nm to 140 nm; A three-layer structure of a middle 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 a 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 structure; a low refractive index layer having an optical thickness of about 15 nm to 30 nm, a high refractive index layer having an optical thickness of about 20 nm to 40 nm, a low refractive index layer having an optical thickness of about 20 nm to 40 nm, The thickness and 240nm~290nm as high refractive index layer, five-layer configuration of the optical thickness 100nm~200nm as low refractive index layer. The range of the refractive index and the thickness of the thin film constituting the antireflection layer is not limited to the above examples. Further, 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 may be any of a wet coating method and a dry coating method. Dry coating methods such as vacuum evaporation, CVD, sputtering, and electron beam evaporation are preferred because a thin film having a uniform thickness can be formed and the thickness of the thin film at the nanometer level can be easily adjusted. And electron beam evaporation are preferred.

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

  After forming at least one of the thin films constituting the anti-reflection layer, visible light is irradiated from the first principal surface side (thin film forming surface side) of the laminate 40, and the reflected light is detected to perform in-line inspection. Will be implemented. By recording the result of this in-line inspection, it is possible to increase the efficiency of the steps such as bonding the antireflection film to another optical film and forming an image display device. For example, if the part determined to be out of specification in the in-line inspection is not supplied to the next process, it is possible to improve the yield of the final product and reduce the frequency of rework. Further, by adjusting the film forming conditions of the thin film based on the result of detecting the reflected light in-line, an antireflection film having excellent uniformity of the reflected light characteristics can be obtained.

  In the following, an example in which 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 will be described in detail. The method of manufacturing the antireflection film will be described with the reflection.

  FIG. 2 is a conceptual diagram showing a configuration example of a film forming apparatus for reflecting a detection result of reflected light in-line on film forming conditions of an 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 of the film forming rolls 281 and 282. Cathodes are provided in each of the film forming chambers, and the respective cathodes 214, 224, 234, and 244 are connected to power sources 216, 226, 236, and 246. On the cathodes 214, 224, 234, 244, targets 213, 223, 233, 243 are arranged so as to face the film-forming rolls 281, 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 a laminate 40 of the transparent film 10 and the film substrate 20 is set on an unwinding roll 251 in the preparation room 250. The stacked body 40 unwound from the unwinding roll is transported onto the first film forming roll 281 and guided to the first film forming chamber 210 and the second film forming chamber 220 in this order. In the first film forming chamber 210, the thin film 51 is formed on the first main surface of the transparent film 10, and in the second film forming chamber 220, the thin film 52 is formed on the thin film 51. The stacked body 45 on which the thin films 51 and 52 are formed is transported 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 anti-reflection film 101 in which the anti-reflection layer 50 composed of four thin films is formed on the transparent film 10 of the laminated body 40 is led to a winding chamber 260 and wound up by a winding roll 261 to form an anti-reflection film. 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 antireflection layer 50 forming surface of the antireflection film 101. The light irradiated from the light irradiation unit may be white light or monochromatic light as long as the light includes visible light. Light irradiation may be continuous or intermittent. The reflected light of the light irradiated from the light irradiation unit 291 to the anti-reflection film 101 is detected by the light detection unit 293. The reflected light detected by the light detection unit 293 is converted into an electric signal by the light receiving element, and the calculation is performed by the calculation unit 273 as necessary. The calculation unit performs 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), and the like. .

  Further, the arithmetic unit 273 determines a difference between the detected reflection characteristic of the 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. Then, a signal is transmitted to the control unit. The control unit 275 adjusts the film forming conditions of the thin film so that the characteristics (reflectance, hue, and the like) of the reflected light fall within a predetermined range.

  The film formation conditions to be adjusted include the amount of gas introduced into the film formation chamber, the film transport speed, the amount of power input, and the like. For example, in the film forming apparatus illustrated in FIG. 2, the control unit 275 controls the rotation speeds of the unwinding roll 251, the winding roll 261, and the film forming rolls 281, 282, the input power amounts of the power supplies 216, 226, 236, and 246, In addition, by adjusting the degree of 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 characteristics of the reflected light is mainly caused by a 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 performed by, for example, PID control. The refractive index can also 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 deposition 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 a reference reflected light characteristic in advance. The reference reflected light characteristic is appropriately determined according to the product standard or the like. As an example, a method based on the center of the standard range of the product or a method based on the reflected light spectrum calculated by optical calculation from the set film thickness and refractive index of each layer (see Examples described later) can be cited. Further, the reflected light spectrum of the product measured off-line may be used as a reference.

  The calculation or measurement of the reference spectrum of the reflected light in the optical calculation or off-line is preferably performed in a state where the back surface reflection is excluded. By defining the reference by excluding the backside reflection, the target reflected light characteristics can be matched with the product specification, and the difference between the reference value and the in-line measurement result can be accurately evaluated.

  After forming all the thin films constituting the anti-reflection layer 50 on the transparent film 10 of the laminate 40, the anti-reflection film 101 preferably has a luminance Y of 0.5% or less in the Yab color system. Note that the Y value in the Yab expression system is the same as the Y value in the XYZ expression system. In the present invention, the Y value of the reflected light can be reduced by using the light-absorbing film base material 20 to reduce back surface reflection. 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.

  If the backside reflection is large and the detection sensitivity is low, in order to keep the product within the standard in a stable manner, consider the difference that may occur between the inline measurement value and the true value and consider the control range of the inline measurement value for safety. Need to be narrower. Therefore, the control range of the 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 range of the inline measurement, the number of products that are originally within the standard is determined to be out of the standard, and the yield of products 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 is increased, and the control range in the manufacturing process can be expanded. Therefore, in addition to facilitating the management of the process based on the in-line measurement result, the yield of the product can be improved.

Further, by suppressing the back surface reflection and reducing the reflection Y value, the difference in chromaticity from the reference spectrum tends to be reduced. Therefore, in-line hue management is also facilitated. The chromaticity difference Δab between the reflected light of the anti-reflection film 101 after forming all the thin films constituting the anti-reflection layer 50 on the transparent film 10 of the laminate 40 and the reference spectrum of the anti-reflection film excluding the back surface reflection is: , 7.5 or less. 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 equation. .
Δab = {(a−a ₀ ) ² + (b−b ₀ ) ² } ^1/2

  As described above, the embodiment in which the in-line detection of the reflected light is performed after forming all the thin films 51, 52, 53, and 54 has been described. However, the in-line detection of the reflected light is performed after forming at least one thin film. 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 irradiation unit 297 irradiates the stacked body 45 with the light before the stack 45 is guided onto the second film forming roll 282. The in-line detection of the reflected light may be performed by detecting the reflected light of the light with the light detection unit 299. Further, in-line detection of reflected light may be performed at two or more locations. For example, in the embodiment shown in FIG. 2, after forming the two layers of thin films 51 and 52, 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. Later, the light detection unit 293 may detect the reflected light from the anti-reflection film 101. If the in-line measurement is performed at two or more locations in this manner, it becomes easy to determine the film forming chamber in which the film forming condition should be adjusted, and more precise control can be performed. Further, in-line detection may be performed at a plurality of locations in the width direction, and the film forming conditions may be adjusted so that the reflected light characteristics in the width direction become uniform. For example, the film formation 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 formed of four thin films, but the number of thin films constituting the antireflection layer is not particularly limited as long as it is two or more as described above. Further, an appropriate film forming apparatus can be used according to 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 method of forming the thin film is not limited to the sputtering method, and various dry coating methods and wet coating methods may be employed. Even when a 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 conditions for forming the thin film based on the results of in-line detection of reflected light.

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

  In this way, before forming the anti-reflection layer to be inspected, the light-absorbing film substrate is stuck to the transparent film to suppress backside reflection and accurately measure the reflected light characteristics in-line. it can. When the antireflection layer is formed by vacuum film formation such as sputtering, it is impossible to extract and inspect the product during the film formation or to bond or 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 substrate 20, the laminate of the transparent film and the film substrate is less expensive than the polarizing plate. Therefore, compared with the case where a polarizing plate is used as in Patent Document 1, even if an out-of-specification portion occurs in the initial stage of the formation of the antireflection layer (before the control of the film formation conditions is started by detecting in-line reflected light), the process loss is reduced. The effect on production cost is small.

  Further, by forming the anti-reflection layer on the laminate 40 of the transparent film 10 and the film substrate 20, the continuous film formation length of the anti-reflection layer is longer than when the anti-reflection layer is formed on the polarizing plate. Can be increased. In general, for the unwind roll 251 and the take-up roll 261, the upper limit of the weight and diameter of a film roll that can be set on a gantry is set. As the film thickness of the film is smaller, the length of the film at which the weight or diameter of the wound body reaches the specified upper limit is larger, so that the length capable of continuous film formation is larger. Generally, the polarizing plate has a configuration in which a transparent protective film is provided on both surfaces of a polarizer and is composed of three films, whereas the laminate 40 can be composed of two films. . Therefore, the thickness of the laminate 40 can be designed to be smaller than that of the polarizing plate, and the continuous film formation length can be increased. As a result, the operation rate of the film forming apparatus is improved, and the productivity can be increased.

[Practical form of anti-reflection film]
In the present invention, for the purpose of measuring the reflected light characteristics of the antireflection film in-line, a laminate (FIG. 3A) in which the film base material 20 is adhered to the second main surface side of the transparent film 10 is used. Can be After the anti-reflection layer 50 is formed on the transparent film 10 (FIG. 3 (B)), and after measuring the reflected light characteristics of the anti-reflection film 101 with the film base, the film base 20 becomes unnecessary. . Therefore, when the antireflection film is put to practical use, it is preferable that the film substrate 20 be peeled off from the transparent film 10.

  In peeling and removing the film substrate, 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 substrate 20 having a release layer 21 on the side of the base film 25 on which the adhesive layer is formed is used, the film substrate 20 is left on the transparent film 10 while the adhesive layer 30 is left. Only can be peeled off. 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.

  At the time of removing the film substrate, as shown in FIG. 3 (C2), the adhesive layer 30 may be peeled off from the transparent film 10 together with the film substrate 20. 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 at the time of forming the anti-reflection layer or for improving the detection accuracy of the reflected light characteristic in-line after the formation of the anti-reflection layer. You. The film substrate is peeled and removed in both cases where the film substrate 20 alone is peeled off with the adhesive layer 30 remaining on the transparent film 10 and where the adhesive layer 30 is also peeled from the transparent film 10 together with the film substrate 20. The later anti-reflection film is put to practical use by being bonded to another film. In order to increase the work efficiency of bonding the antireflection film to another film, it is preferable to perform the bonding inline using a roll laminator or the like. Therefore, it is preferable that the peeling operation of the film substrate 20 performed between the inline inspection of the reflected light characteristic and the lamination with another film is also performed inline.

  In order to stably remove the film substrate 20 from the transparent film 10 after forming the antireflection layer 50 in-line and stably, it is preferable that the peeling force of the film substrate 20 from the transparent film 10 is small. Specifically, the peeling force in a 180 ° peeling test (peeling speed: 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 are more preferred. By adjusting the composition of the adhesive layer 30 or providing a release layer on the surface of the film substrate, the peeling force can be reduced.

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

  When the antireflection film is put to practical use, 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 a combination thereof. As an example of a practical embodiment, a polarizing plate with an antireflection layer can be obtained by laminating an antireflection film and an optical film including a polarizer. In this manner, in a mode in which the antireflection layer is formed on the transparent film and then bonded to a polarizer or the like, without exposing the polarizer to a high-temperature environment or high-power plasma for forming the antireflection layer, A polarizing plate with an antireflection layer is obtained. Therefore, defects such as deterioration of the polarizer can be suppressed, and the yield can be increased.

  4A and 4B are cross-sectional views schematically illustrating a configuration example of a polarizing plate with an antireflection layer. In the polarizing plate 121 with an anti-reflection layer shown in FIG. 4A, one surface of a polarizer 79 is attached to the second main surface of the transparent film 10 with an adhesive layer 36 interposed therebetween. A transparent protective film 74 is attached 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.

  Examples of the polarizer 79 include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene-vinyl acetate copolymer-based partially saponified film, and dichroic properties such as iodine and a dichroic dye. Examples include a uniaxially stretched film obtained by adsorbing a substance, and a polyene-based oriented film such as a polyvinyl alcohol dehydration product and a polyvinyl chloride dehydrochlorination product.

  Above all, from the viewpoint of having a high degree of polarization, polyvinyl alcohol, and a polyvinyl alcohol-based film such as partially formalized polyvinyl alcohol, a dichroic substance such as iodine or a dichroic dye was adsorbed and oriented in a predetermined direction. Polyvinyl alcohol (PVA) polarizers are preferred. For example, a PVA-based polarizer can be obtained by applying iodine dyeing and stretching to a polyvinyl alcohol-based film. As the PVA-based polarizer, a thin polarizer having a thickness of 10 μm or less can be used. Examples of the thin polarizer include those described in, for example, JP-A-51-069694, JP-A-2000-338329, WO2010 / 100917, pamphlet No. 4691205, Japanese Patent No. 4751481, and the like. Thin polarizing film. Such a thin polarizer is obtained, for example, by a manufacturing method including a step of stretching a PVA-based resin layer and a resin substrate for stretching in a state of a laminate, and a step of iodine dyeing.

  As the transparent protective film 74, the same materials as 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.

  Examples of the adhesive 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 polymers. A polymer having a base polymer such as a polymer or a rubber-based polymer can be appropriately selected and used. For bonding the PVA-based polarizer, a polyvinyl alcohol-based adhesive is preferably used.

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

  The adhesive layer 35 used for bonding the transparent protective film 73 and the transparent film 10 is preferably an adhesive such as an acrylic adhesive, a rubber adhesive, or a sea cone adhesive. The adhesive layer 30 (adhesive) used for the temporary attachment of the transparent film 10 and the film substrate 20 can be used as it is (see FIGS. 3B and 3C).

  The antireflection film is preferably used for forming an image display device. When the antireflection film is mounted on the outermost surface of the image display device, the antireflection film is susceptible to contamination (fingerprint, dirt, dust, etc.) from the external environment. For the purpose of preventing contamination from such an external environment and imparting easy removal of contamination, an antifouling layer made of a silane compound containing a fluorine group or an organic compound containing a fluorine group 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 the reflected light of the laminate obtained by laminating various film substrates via an adhesive layer on the side opposite to the antireflection layer forming surface of the antireflection film was calculated by optical simulation. did. As the 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. A titanium oxide layer with a thickness of 12 nm (refractive index 2.35), a silicon oxide layer with a thickness of 28 nm (refractive index 1.46), a titanium oxide layer with a thickness of 100 nm (refractive index 2.35), and a film thickness A configuration including an antireflection layer composed of four layers of a silicon oxide layer of 85 nm (refractive index: 1.46) was adopted.

<Example 1>
A black film having a thickness of 38 μm (visible light transmittance: 3%, refractive index: 1.65) is adhered to the surface of the anti-reflection film on which the anti-reflection layer is not formed, via an adhesive layer (refractive index: 1.48) having 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 bonded to a 20 μm thick adhesive layer (refraction). A ratio of 1.48) to the surface of the anti-reflection film where the anti-reflection layer is not formed.

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

<Evaluation>
With respect to 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. Further, the reflected light spectrum (reference spectrum) of the antireflection film when the back surface reflection was set to zero was calculated. From the obtained backlight spectrum, the luminance Y (%) in the Yab color system and the chromaticities a and b were calculated, and the chromaticity difference Δab between the reflected light of each example and comparative example and the reference spectrum was calculated. . 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 peeling force and in-line peeling property]
In the following, a sample for evaluation was prepared by bonding a film substrate to a TAC film (manufactured by Fuji Film; Fujitak TD80UL) having a thickness of 80 μm via an adhesive layer, and the peeling force was evaluated.

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

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

<Sample 3>
Using a roll laminator, a 20 μm thick transparent pressure-sensitive adhesive sheet (Nitto Denko-made acrylic pressure-sensitive adhesive sheet made by Nitto Denko) was stuck on the TAC film, and a 38 μm-thick PET film (the surface of which was release-treated) was laminated thereon. The release treated surface of Mitsubishi Foil; Diafoil MRF38) was bonded.

<Evaluation>
For Samples 1 and 2, a peel test was performed at the interface between the TAC film and the adhesive layer, and for Sample 3, a peel test was performed 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 peeling force was measured by a 180 ° peel test (test speed: 10 m / min).
(In-line 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 off without any problem were evaluated as “good”, and those with abnormal tension during film running were evaluated as “defective”. did.
Table 2 shows the results.

  As shown in Table 1, by lowering the transmittance of the film substrate, the back surface reflectance is reduced, the Y value of the reflected light is reduced accordingly, 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 a base film was used, the Y value and the chromaticity difference tended to increase as compared with Example 1 due to an increase in the reflection interface. By adjusting the refractive index of the release layer, backside reflection can be reduced.

  As shown in Table 2, by reducing the peeling force between the transparent film and the film substrate, in-line peeling tends to be facilitated. From these results, if the peeling force 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 may be changed after the anti-reflection layer is formed. It can be seen that the workability when the film is replaced with 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 100, 101, 103 Antireflection film 111, 112 Antireflection film (optical film with antireflection layer)
121,122 Anti-reflection film (Polarizing plate with anti-reflection layer)

Claims (12)

A method for producing an antireflection film including an antireflection layer on a first main surface of a transparent film,
A laminate preparing step of preparing a laminate in which a film substrate is releasably adhered to the second main surface of the transparent film via an adhesive layer;
An anti-reflection layer forming step of forming an anti-reflection layer composed of two or more thin films on the first main surface of the transparent film of the laminate; and forming at least one of the thin films constituting the anti-reflection layer. After the film, irradiating visible light from the surface on which the thin film is formed, an in-line inspection step of detecting the reflected light,
The laminate of the film substrate and the adhesive layer has a visible light transmittance of 3% or less,
The method for manufacturing an anti-reflection film, wherein the anti-reflection layer forming step and the in-line inspection step are continuously performed while transporting the laminate in one direction.   The reflection according to claim 1, wherein in the in-line inspection step, after all of the plurality of thin films constituting the anti-reflection layer are formed, visible light is emitted from the surface on which the thin film is formed, and the reflected light is detected. Production method of the prevention film.   The method of manufacturing an anti-reflection film according to claim 1, wherein a film forming condition of the thin film in the anti-reflection layer forming step is adjusted according to a detection result of the reflected light in the in-line inspection step.   The reflective surface of visible light when light enters the laminate of the film base material and the adhesive layer from the adhesive layer side is 1.0% or less. 3. The method for producing an antireflection film according to 1.   The method for producing an antireflection film according to any one of claims 1 to 4, wherein the adhesive layer is a pressure-sensitive adhesive layer.   The method for producing an antireflection film according to claim 5, 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 6, wherein a peel force of the transparent film and the film substrate in a 180 ° peel test is 2 N / 50 mm or less.   The method for producing an antireflection film according to any one of claims 1 to 7, further comprising a peeling step of peeling the film substrate from the transparent film after the inline inspection step.   The method for producing an antireflection film according to claim 8, wherein after the peeling step, an optical film is bonded on a second main surface of the transparent film.   The method according to claim 8, 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 substrate is releasably attached to the second main surface of the transparent film via an adhesive layer,
An antireflection film, wherein a laminate of the film substrate and the adhesive layer has a visible light transmittance of 3% or less. A method for measuring the reflected light characteristics of an antireflection film including an antireflection layer composed of two or more thin films on a first main surface of a transparent film,
On the second main surface of the transparent film, in a state where the film substrate is peelably adhered via the adhesive layer, detection of reflected light of visible light emitted from the first main surface is performed. ,
The laminate of the film substrate and the adhesive layer has a visible light transmittance of 3% or less,
The method for measuring reflected light characteristics, wherein the detection of the reflected light is continuously performed while conveying the antireflection film in one direction.

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