KR20170042510A - Antireflective film and manufacturing method thereof, and method of measuring reflected light characteristics of antireflective film - Google Patents

Abstract

The method of the present invention comprises a laminate preparing step of preparing a laminate 40 on a second main surface of a transparent film 10 in which a film base material 20 is adhered in a releasable manner via an adhesive layer 30, An antireflection layer forming step of forming an antireflection layer (50) composed of two or more thin films on a first main surface of a transparent film; and a step of forming an antireflection layer (50) And an in-line inspection step of detecting the reflected light. The adhesive layer 30 is a diffusion pressure-sensitive adhesive layer having a haze of 40% or more. The antireflection layer forming step and the inline inspecting step are carried out continuously while conveying the laminate 40 in one direction. The uniformity is improved by adjusting the deposition condition of the thin film in the anti-reflection layer forming process in accordance with the detection result of the reflected light in the inline inspection process.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an antireflection film, a method of manufacturing the same, and a method of measuring a reflected light characteristic of an antireflection film.

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

BACKGROUND ART An antireflection film is used on the visual side surface of an image display device such as a liquid crystal display or an organic EL display for the purpose of preventing deterioration of image quality due to reflection of external light or image, The antireflection film comprises, on a transparent film, an antireflection layer comprising a plurality of thin film stacks having different refractive indices.

As one form of the antireflection film, a polarizing plate having an antireflection layer can be given. The polarizing plate on which the antireflection layer is formed is formed by bonding an antireflection film to the surface of the polarizing plate or by bonding an antireflection film as a protective film to the surface of the polarizer. It is also known to form a polarizing plate on which an antireflection layer is formed by forming an antireflection layer on a polarizing plate (for example, Patent Document 1).

Japanese Unexamined Patent Application, First Publication No. Hei 8-136730

The antireflection layer reduces the reflectance of visible light by using multiple reflection interference of the thin film. Therefore, when the refractive index and the film thickness of the thin film change, the reflected light characteristics such as reflectance and reflected light color change. Even in the case where the film formation conditions of the thin film are strictly controlled and kept constant in the formation of the antireflection layer, the film thickness, the refractive index, etc. of the thin film slightly fluctuate due to variations in the characteristics of the raw materials, do. Such slight fluctuation has a small influence on the reflection light characteristic. Therefore, in general, the quality of the antireflection film is controlled by depositing the film under a predetermined condition, checking off-line after the film formation, and checking reflected light characteristics with an inspection apparatus such as a spectrophotometer or the naked eye.

In recent years, demand for an antireflection film has increased as the display has become finer and more refined, and an antireflection film having a lower reflectance and less coloring of reflected light is required. In addition, attempts have been made to neutralize the outgoing light from the panel by adjusting the color of the reflected light. For example, when the light emitted from the panel is yellowish, the reflection is made to be blue by using an anti-reflection film.

It has been demanded to more strictly control the reflected light characteristics of the antireflection film in accordance with the increase in the required characteristics. Therefore, the antireflection film deviates from the quality standard due to the change of the reflected light characteristic caused by slight fluctuation of the manufacturing conditions. Therefore, in the production process of the antireflection film, it is necessary to control film forming conditions more strictly to suppress variations in the refractive index and the film thickness of the thin film and to keep the reflected light characteristics constant.

In the film production, in-line measurement is performed in the manufacturing process, and the measurement result is fed back to the previous process so that the quality of the film is kept constant. However, the thickness of the thin film constituting the antireflection layer is from several nm to several tens nm, and it is not easy to directly measure the thickness thereof. In particular, it is very difficult to measure the film thickness of each thin film in a plurality of thin film stacks. Therefore, it is conceivable to measure the reflected light characteristic in-line at the time of film formation of a thin film, and to feed back the measurement result to the film formation condition of the thin film. In the measurement of the reflected light characteristic in the in-line, it is necessary to exclude the influence of the back surface reflection.

Generally, the antireflection film is designed so that the visible light reflectance of the antireflection layer-formed surface is 1% or less, while the visible light reflectance on the back side of the transparent film (the interface between the transparent film and the air) is about 4%. In the off-line inspection after forming the antireflection layer, the influence of the back surface reflection can be excluded, and the reflected light characteristics on the surface side can be measured. On the other hand, most of the reflected light detected by the inline inspection in the production process of the antireflection film is the reflected light from the back surface, and even if the characteristics (reflection color, etc.) of the reflected light from the antireflection layer- I never do that. Therefore, it is not easy to accurately measure the reflected light characteristic from the surface side of the antireflection layer formed in-line.

Patent Document 1 proposes a method of arranging a polarizer (analyzer) on the surface of the polarizing plate on which the antireflection layer is formed when the antireflection layer is formed on the surface of the polarizing plate to measure the reflectance. Since the reflected light from the back side of the polarizing plate on which the antireflection layer is formed is absorbed by the analyzer when the polarizing plate on which the antireflection layer is formed and the analyzer are arranged so that their absorption axis directions are orthogonal to each other, Can be measured.

However, this method can not be applied to the case where the antireflection layer is formed on the polarizing plate. The polarizing plate has a structure in which a transparent film is laminated on both sides of a polarizer and is higher than a transparent film. Therefore, in the method of forming the antireflection layer on the polarizing plate, an increase in the manufacturing cost due to the process loss in the case where the out-of-specimen portion occurs at the beginning of the formation of the antireflection layer (before the control of the film formation conditions by in- It is easy to become remarkable. In addition, the characteristics of the polarizing plate may be deteriorated due to the film forming environment of the antireflection layer. For example, when a polarizing plate is introduced into a sputtering film forming apparatus, there is a fear that the polarizer is deteriorated by exposure to a high-temperature environment or a high-output plasma.

Therefore, from the viewpoints of productivity improvement and cost reduction, a method of precisely measuring the reflected light characteristic by eliminating the influence of the back surface reflection is required in forming the antireflection layer on the transparent film not including the polarizer. An object of the present invention is to obtain an antireflection film having excellent uniformity by detecting a change in reflected light characteristic more accurately in inline in the process of forming an antireflection layer on a transparent film and reflecting the result of the detection in film forming conditions . It is another object of the present invention to provide a method for in-line measurement of reflected light characteristics of an antireflection film.

As a result of studying the above, it has been found that the use of a laminate in which a film base is peelably adhered (adhered) to a back side of a transparent film through an adhesive layer reduces back reflection, and the refractive index, It has been found that it is possible to detect a change in the characteristic of reflected light caused by slight fluctuation.

One form of the antireflection film of the present invention is an antireflection film on which a film base is provided with an antireflection layer on one side of a transparent film and a film base adhered to the other side via an adhesive layer so as to be peelable.

The antireflection film on which the film substrate is formed is obtained by preparing a laminate on which a film substrate is adhered to a second main surface of the transparent film via an adhesive layer in such a manner that the film substrate can be peeled off (laminate preparation step) (Antireflection layer forming step) of forming an antireflection layer composed of two or more thin films on one main surface. In forming the antireflection 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 inline (in-line inspection step). The formation of the antireflection layer and the inline inspection are carried out continuously while conveying the laminate in one direction. It is preferable that the film forming conditions of the thin film are adjusted in accordance with the detection result of the reflected light in the inline inspection. This makes it possible to maintain the reflected light characteristics of the antireflection film uniformly and to improve the stability of the quality.

The adhesive layer used for bonding the transparent film and the film substrate is preferably a diffusion pressure sensitive adhesive layer having a haze of 40% or more. By using a high diffusing pressure sensitive adhesive layer as the adhesive layer, incident light from the first main surface side of the transparent film is diffused in the adhesive layer, so that light reflection on the back side of the transparent film is reduced.

After forming the antireflection layer on the transparent film, the film substrate is peeled off (peeling step). Then, another optical film such as a polarizing plate is stuck on the second main surface of the transparent film, and an antireflection film is provided for practical use.

By forming the antireflection layer on the laminated body whose reflection on the back surface is reduced, the detection accuracy of the reflected light and the reproducibility of detection in the inline inspection are improved. In addition, an anti-reflection film excellent in the uniformity of reflected light characteristics can be obtained by feeding back the detection result of in-line reflected light to the thin film forming condition.

1 is a cross-sectional view schematically showing one form of an antireflection film having a film substrate formed thereon.
2 is a conceptual diagram showing a configuration example of a film forming apparatus for an antireflection layer.
3 (A) is a cross-sectional view that schematically shows a configuration example of a laminate used for forming an antireflection film, (B) shows a configuration example of an antireflection film having a film base on which an antireflection layer is formed Fig. (C1) and (C2) are cross-sectional views schematically showing a configuration example of an anti-reflection film after peeling off a film substrate. (D1) and (D2) are cross-sectional views schematically showing a configuration example of an antireflection film to which other films are bonded.
4 (A) and 4 (B) are cross-sectional views schematically showing a configuration example of a polarizing plate on which an antireflection layer is formed.

[Composition of antireflection film]

1 is a cross-sectional view schematically showing a configuration of an antireflection film according to an embodiment. The antireflection film 101 of FIG. 1 has 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 adhered to be peelable via the adhesive layer 30. [ The antireflection layer is a laminate of two or more thin films. In Fig. 1, an antireflection layer 50 composed of a laminate of four thin films 51, 52, 53, and 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 formed by a method of forming a cured coating of a suitable ultraviolet curable resin such as acrylic or silicone on the surface of the film.

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

Examples of the resin material constituting the transparent film include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN); Cellulosic polymers such as diacetylcellulose and triacetylcellulose; Acrylic polymers such as polymethyl methacrylate; Styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer; Cyclic polyolefins such as polynorbornene; And polycarbonate.

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

(Adhesive layer)

The transparent film 10 and the film substrate 20 are bonded via the adhesive layer 30. The material of the adhesive layer 30 is not particularly limited, but a pressure-sensitive adhesive is preferably used in order to peelably adhere the film substrate 20. As the pressure-sensitive adhesive, for example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive and the like can be used. Among them, an acrylic pressure-sensitive adhesive mainly comprising an acrylic polymer is preferably used.

The adhesive layer 30 is a light scattering pressure-sensitive adhesive layer. By using the light scattering pressure-sensitive adhesive, the light transmitted through the transparent film 10 is scattered by the adhesive layer 30, and the back surface reflection can be reduced. The larger the haze of the adhesive layer 30 (light scattering pressure-sensitive adhesive layer) is, the larger the light scattering in the adhesive layer becomes, and the back surface reflection tends to be reduced. Therefore, the haze of the adhesive layer 30 (light scattering pressure-sensitive adhesive layer) is preferably 40% or more, more preferably 50% or more, more preferably 70% or more, and particularly preferably 90% or more.

The composition of the light-scattering pressure-sensitive adhesive layer is not particularly limited as long as the haze is in the above range. Examples of the light scattering pressure-sensitive adhesive include those obtained by dispersing particles in a pressure-sensitive adhesive. Examples of the particles contained in the light scattering pressure-sensitive adhesive include inorganic fine particles and fine polymer particles. The particles are preferably polymer microparticles. Examples of the material of the polymer fine particles include a silicone resin, a polymethyl methacrylate resin, a polystyrene resin, a polyurethane resin, and a melamine resin. These resins are excellent in dispersibility in a pressure-sensitive adhesive, and have a proper refractive index difference with a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, so that a light-scattering pressure-sensitive adhesive layer excellent in diffusion performance can be obtained. The shape of the particles is not particularly limited, and examples thereof include spherical spheres, flat spheres, irregular shapes, and the like. The particles may be used alone or in combination of two or more.

The volume average particle diameter of the particles is preferably 1 to 10 占 퐉, more preferably 1.5 to 5 占 퐉. By setting the volume average particle diameter in the above range, excellent light scattering performance can be imparted. The volume average particle diameter can be measured, for example, by using an apparatus for measuring automatic particle size distribution of a grassland. 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 blending amount of the particles within the above range, a light-scattering pressure-sensitive adhesive layer having excellent light scattering performance can be obtained.

(Film substrate)

In the production of the antireflection film, the film substrate 20 is peelably adhered to the second main surface (the surface on which the antireflection layer 50 is not formed) of the transparent film 10 via the adhesive layer 30, Body 40 is used. The film base material 20 is adhered to the surface of the adhesive layer 30 so that the exposed surface of the adhesive layer 30 is covered to contaminate the adhesive layer due to contact with the outside and to adhere the adhesive Can be prevented.

As the film substrate 20, a resin film is used. The material of the film substrate 20 may be transparent or opaque, and examples thereof include polyesters, cellulose polymers, acrylic polymers, styrene polymers, amide polymers, polyolefins, cyclic polyolefins, and polycarbonates.

By using a material having a small visible light reflectance as the film substrate 20, it is possible to further reduce the back reflection when light is irradiated from the first main surface side. In order to further reduce the back surface reflection, the back surface reflectance of the visible light of the film base when light is incident from the first main surface is preferably 1.0% or less, more preferably 0.7% or less, more preferably 0.5% , And particularly preferably 0.3% or less. The visible light reflectance is measured in accordance with JIS R3106: 1998.

Examples of the low reflectance film substrate include a light absorbing film and a light scattering film having fine irregularities on the surface. Particularly, when the light absorbing film is used, the back reflection reducing effect is easily obtained. 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, in order to further reduce the back surface reflection by using the light absorbing film base material .

For example, a light absorbing film base material can be obtained by adding a black pigment such as carbon black to the resin material of the film base material or by forming a colored layer of black ink or the like on the surface of the film base material. The colored layer may be formed on only one side of the film base, or on both sides of the film base. In the case where a light absorbing film having a colored layer is used as the film substrate 20, at least the surface of the film base material on the side of the transparent film 10, from the viewpoint of suppressing light reflection at the interface on the transparent film 10 side, It is preferable that a colored layer is formed on the substrate. The thickness of the colored layer is, for example, about 0.5 탆 to 10 탆.

As shown in Fig. 3 (C1) and Fig. 3 (C2), the film substrate 20 is peeled off when the antireflection film is practically used. That is, the film substrate 20 is a process material not included in the final product. Therefore, the film substrate is preferably as low 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 base material is small, the length of the continuous film formation when the antireflection layer 50 is formed on the layered product 40 can be made long, and the productivity of the antireflection film can be improved. Therefore, it is preferable that the thickness of the film substrate 20 is as thin as possible within a range that does not impair the film forming property and the handling property. The thickness of the film base material is preferably from 5 mu m to 200 mu m, more preferably from 10 mu m to 130 mu m, and further preferably from 15 mu m to 110 mu m.

(Laminate)

As described above, when the laminate 40 having the adhesive layer 30 and the film substrate 20 formed of the diffusion adhesive on the second main surface of the transparent film 10 is irradiated with light from the first main surface side of the transparent film The back reflection of the light is small. Table 1 shows measurement examples of the back surface reflectance of the laminate. In the samples 1 to 5, a triacetyl cellulose film having a thickness of 40 탆 in which an acrylic hard coat layer was formed on the first main surface was used as the transparent film 10, and a transparent PET film having a thickness of 38 탆 was used as the film substrate 20 Respectively. The haze ratio of the pressure-sensitive adhesive layer was changed by changing the particle diameter and the content of the particles to be dispersed in the pressure-sensitive adhesive using an acrylic pressure-sensitive adhesive having a thickness of 20 mu m as the adhesive layer 30. [

The back surface reflectance of Example 1 using a transparent pressure-sensitive adhesive not containing particles was 4% and was substantially the same as the back surface reflectance of the transparent film 10 itself. When the haze of the pressure-sensitive adhesive layer was increased to 40%, the back surface reflectance decreased to 1%, and when the haze was increased to 60%, the back surface reflectance became less than 0.5%. As described above, the surface reflectance of the antireflection film is 1% or less. It is necessary to set the back surface reflectance of the layered product 40 to be equal to or less than the surface reflectance, that is, 1% or less, in order to reduce the effect of reflection on the back surface and accurately detect the reflected light characteristics from the surface. The reflectivity on the back surface is preferably 0.7% or less, more preferably 0.5% or less, further preferably 0.3% or less. From the results shown in Table 1, it can be seen that the back surface reflectance of the layered product 40 can be adjusted to the above range by increasing the haze of the adhesive layer 30.

(Antireflection layer)

The antireflection layer 50 is formed on the first main surface of the laminate body 40 on which the film base material 20 is adhered via the adhesive layer 30 on the second main surface of the transparent film 10. The antireflection layer 50 is formed of a thin film of two or more layers. In general, the antireflection layer adjusts the optical film thickness (the refractive index and thickness product) of the thin film so that the reversed phases of the incident light and the reflected light cancel each other out. By making the antireflection layer a multilayer laminate of a thin film of two or more layers having different refractive indices, the reflectance can be made small in the wavelength range of visible light.

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, a high refractive index material having a refractive index of about 1.80 to 2.40, such as silicon oxide or magnesium fluoride, may be used as the material of titanium oxide, niobium oxide, zirconium oxide, tin doped indium oxide (ITO), antimony doped oxide Tin (ATO), and the like. In addition to the low refractive index layer and the high refractive index layer, titanium oxide or a mixture of the low refractive index material and high refractive index material (a mixture of titanium oxide and silicon oxide, for example) as a medium refractive index layer having a refractive index of about 1.50 to 1.85 A thin film may be formed.

The laminated structure of the antireflection layer 50 may be 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 Configuration ; A three-layer structure of a medium refractive index layer having an optical film thickness of about 170 nm to 180 nm, a high refractive index layer having an optical film thickness of about 60 nm to 70 nm, and a low refractive index layer having an optical film thickness of about 135 nm to 145 nm; A high refractive index layer having an optical film thickness of about 25 nm to 55 nm, a low refractive index layer having an optical film thickness of about 35 nm to 55 nm, a high refractive index layer having an optical film thickness of about 80 nm to 240 nm, A four-layer structure of a low refractive index layer of about 150 nm; 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, A five-layer structure of a high refractive index layer of about 290 nm and a low refractive index layer of an optical film thickness of about 100 nm to 200 nm, and the like. The range of the refractive index and film thickness of the thin film constituting the antireflection layer is not limited to the above example. The antireflection layer 50 may be a laminate of thin films of six or more layers.

[Method of forming antireflection layer]

The film forming method of the thin film constituting the antireflection layer is not particularly limited, and either wet coating method or dry coating method may be used. Dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam deposition are preferable from the viewpoint that a thin film having a uniform film thickness can be formed and that the film thickness of the nanometer level thin film can be easily adjusted. Electron beam deposition is preferred.

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

After at least one layer of the thin film constituting the antireflection layer is formed, visible light is irradiated from the first main surface side (thin film formation surface side) of the laminate body 40, and the in-line inspection is performed by detecting the reflected light. By recording the results of the in-line inspection, it is possible to efficiently perform processes such as bonding of the antireflection film and another optical film and formation of an image display device. For example, if the portion determined to be out of specification in the inline inspection is not supplied to the next process, the yield of the final product or the frequency of the work can be reduced. In addition, an anti-reflection film having excellent uniformity of reflected light characteristics can be obtained by adjusting the film forming conditions of the thin film based on the reflected light detection result in line.

Hereinafter, the case where the antireflection layer 50 made of 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, A method for manufacturing an antireflection film while reflecting the film formation conditions will be described.

Fig. 2 is a conceptual diagram showing a configuration example of a film forming apparatus for reflecting the result of detection of in-line reflected light to the film forming conditions of the antireflection layer. The film forming apparatus of Fig. 2 has two film forming rolls 281, 282. A plurality of deposition chambers 210, 220, 230, and 240 partitioned by barrier ribs are provided along the circumferential direction of each of the deposition rolls 281 and 282. A cathode is formed in each of the deposition chambers, and cathodes 214, 224, 234, and 244 are connected to power sources 216, 226, 236, and 246, respectively. Targets 213, 223, 233, and 243 are disposed on the cathodes 214, 224, 234, and 244 so as to face the film formation rolls 281 and 282, respectively. A gas introduction tube is connected to each of the deposition chambers 210, 220, 230, and 240, and valves 219, 229, 239, and 249 are provided upstream of the gas introduction tube.

A winding body of the laminated body 40 of the transparent film 10 and the film base 20 is set on a take-up roll 251 in the preparation chamber 250. The laminated body 40 wound from the unwinding roll is transported onto the first film formation roll 281 and sequentially guided to the first film formation chamber 210 and the second film formation chamber 220. The thin film 51 is deposited on the first main surface of the transparent film 10 in the first deposition chamber 210 and the thin film 52 is deposited on the thin film 51 in the second deposition chamber 220. The layered product 45 on which the thin films 51 and 52 are formed is transported onto the second film formation roll 282 and transported to the third film formation chamber 230 and the fourth film formation chamber 240 by the thin film 53 and the thin film 54 are sequentially formed. The antireflection film 101 having the antireflection layer 50 formed of the thin film of four layers on the transparent film 10 of the laminate 40 is guided to the winding room 260 and wound on the winding roll 261 Whereby a wound body of the antireflection film is obtained.

The light irradiation portion 291 and the light detection portion 293 are disposed in the winding chamber 260 so as to face the surface on which the antireflection film 50 of the antireflection film 101 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 reflected by the anti-reflection film 101 from the light irradiating unit 291 is detected by the light detecting unit 293. The reflected light detected by the photodetector 293 is converted into an electric signal by the light receiving element, and arithmetic operation is performed by the arithmetic unit 273 as necessary. The calculation unit performs spectrum calculation of the detected reflected light and conversion into a specific color system (for example, XYZ color system, L * a * b * color system, Yab color system).

The calculation unit 273 also determines the difference between the reflected characteristic of the detected reflected light and the desired reflected light characteristic and sends a signal to the control unit to change the film forming condition of the thin film when the difference exceeds the threshold value do. The control unit 275 adjusts the film forming conditions of the thin film such that the characteristics (reflectance, color, etc.) of the reflected light are within a predetermined range.

Film formation conditions to be subjected to adjustment include the amount of gas introduced into the film formation chamber, the transport speed of the film, the amount of supplied power, and the like. 2, the control unit 275 controls the rotation speed of the take-up roll 251, the take-up roll 261, and the film formation rolls 281 and 282, the power sources 216, 226, 236, 246, and the degree of opening of the valves 219, 229, 239, 249 of the gas introduction pipe, the film forming conditions in the respective film forming chambers can be adjusted. The change in the characteristic of the reflected light is mainly caused by the fluctuation of the film thickness of the thin film. Therefore, it is preferable that the film forming conditions of the thin film are adjusted so that the film thickness of the thin film approaches the set value. The film formation condition adjustment is executed by, for example, PID control. It is also possible to change the refractive index by adjusting the production 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 the above description, the inline detection of the reflected light is performed after all the thin films 51, 52, 53, and 54 are formed. However, the inline detection of the reflected light can be performed at any stage after at least one thin film is formed . For example, after the thin films 51 and 52 are formed on the first film formation roll 281 and the layered product 45 is guided onto the second film formation roll 282, The in-line detection of the reflected light may be performed by detecting the light reflected by the light source unit 45 by the light detecting unit 299. In addition, in-line detection of reflected light may be performed at two or more points. For example, in the embodiment shown in Fig. 2, after the formation of the two thin films 51 and 52, the reflected light from the laminate 45 is detected by the photodetector 299, The reflection light from the anti-reflection film 101 may be detected by the photodetector 293 after the thin films 53 and 54 are formed. When the in-line measurement is performed at two or more points in this manner, it is easy to determine the film formation chamber in which film formation conditions need to be adjusted, and more precise control becomes possible. Further, in-line detection may be performed at a plurality of points 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, it is possible to adjust film forming conditions in the width direction by changing the amount of gas introduced in the width direction.

2 shows an example in which the antireflection layer 50 is formed of a thin film of four layers, the number of thin films constituting the antireflection layer is not particularly limited as long as it is two or more layers. In addition, 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 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 excellent in uniformity of reflected light characteristics can be obtained by adjusting the thin film forming conditions based on the inline detection result of reflected light.

When light is irradiated onto 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 reflection on the second main surface side, and the reflected light from the first main surface side (antireflection layer formation surface) It is difficult to detect. On the other hand, by forming a light-scattering pressure-sensitive adhesive layer on the second main surface side of the transparent film 10, the back surface reflection is suppressed. In this embodiment, since most of the reflected light detected by the photodetector 293 is reflected light from the first main surface side (the antireflection layer forming surface side), a slight change in the reflected light characteristic from the first main surface side is detected in-line . By adjusting the film forming conditions of the thin film based on the detection result, it is possible to manufacture an antireflection film excellent in uniformity of reflected light characteristics.

Thus, before the antireflection layer to be inspected is formed, the film base is adhered to the transparent film via the light scattering adhesive layer, whereby the back reflection can be suppressed and the reflected light characteristic can be accurately measured in-line. As described above, since the inexpensive general-purpose film is used as the film substrate 20, the laminate of the transparent film and the film substrate is inexpensive as compared with the polarizing plate. Therefore, compared with the case of using the polarizing plate as in Patent Document 1, even when an out-of-specifi c part occurs in the initial stage of formation of the antireflection layer (before the start of control of the film formation condition by inline reflection light detection) Is small.

Further, by forming the antireflection layer on the laminate 40 of the transparent film 10 and the film base 20, the continuous film formation length of the antireflection layer can be made longer than when the antireflection layer is formed on the polarizing plate . In general, the weight of the winding roll 251 or the winding roll 261 and the upper limit of the diameter of the wound film roll are set. The thinner the film thickness, the longer the length of the film in which the weight or the diameter of the winding reaches the upper limit of the prescribed length, and thus the length of the continuous film formation becomes longer. In general, the polarizing plate has a structure in which a transparent protective film is formed on both sides of a polarizer and is composed of three films, while the laminate 40 can be composed of two films. Therefore, the layered product 40 can be designed to have a thinner thickness than the polarizing plate, and the length of the continuous film formation can be made longer. As a result, the operating rate of the film forming apparatus is improved, and the productivity can be increased.

[Practical form of antireflection film]

In the present invention, a laminate (FIG. 3 (A)) in which the film base material 20 is adhered to the second main surface side of the transparent film 10 is used for the purpose of in-line measurement of the reflected light characteristics of the antireflection film. After the antireflection layer 50 is formed on the transparent film 10 (Fig. 3 (B)) and the reflected light characteristic of the antireflection film 101 on which the film substrate is formed is measured, Becomes unnecessary. Therefore, when the antireflection film is provided for practical use, it is preferable that the film base material 20 is peeled off from the transparent film 10.

3 (C1), only the film substrate 20 is peeled off in a state in which the adhesive layer 30 is attached to the transparent film 10, for example. For example, if the film substrate 20 is subjected to a release treatment on the side where the adhesive layer 30 is formed, only the film substrate 20 can be peeled off without leaving the adhesive layer 30 on the transparent film 10. After the film substrate is removed, the other film 71 is bonded to the second main surface of the transparent film 10 via the adhesive layer 30.

The adhesive layer 30 may be peeled off from the transparent film 10 together with the film substrate 20 as shown in Fig. 3 (C2). After the film substrate is removed, the other film 72 is bonded to the second main surface of the transparent film 10 via the other adhesive layer 33.

The films 71 and 72 to be adhered to the second main surface of the transparent film 10 after peeling the film substrate 20 are not particularly limited. For example, an optical film comprising a polarizer, a polarizer protective film, an optical compensation film (retardation film), or an optical film comprising a combination thereof is bonded to an antireflection film to obtain an optical film on which an antireflection layer is formed. As an example of a practical form, a polarizing plate having an antireflection layer is obtained by bonding an antireflection film and an optical film containing a polarizer. As described above, in the embodiment in which the antireflection layer is formed on the transparent film and the antireflection layer is bonded with the polarizer or the like, a polarizing plate having an antireflection layer is obtained without exposing the polarizer under a high-temperature environment or a high-output plasma for forming the antireflection layer . Therefore, problems such as deterioration of the polarizer can be suppressed and the yield can be increased.

4 (A) and 4 (B) are cross-sectional views schematically showing a configuration example of a polarizing plate on which an antireflection layer is formed. In the polarizing plate 121 having the antireflection layer shown in Fig. 4 (A), one surface of the polarizer 79 is bonded onto the second main surface of the transparent film 10 with the 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. A release film 22 is formed on the surface of the transparent protective film 74 with an adhesive layer 39 interposed therebetween. Is attached.

As the polarizer 79, a dichroic substance such as iodine or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially porous polyvinyl alcohol film, or an ethylene / vinyl acetate copolymerization system partial saponification film A monoaxially stretched film, a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride.

Among them, from the viewpoint of having a high degree of polarization, a polyvinyl alcohol film such as polyvinyl alcohol or partially formalized polyvinyl alcohol, which is obtained by adsorbing a dichroic substance such as iodine or a dichroic dye to a poly A vinyl alcohol (PVA) based polarizer is preferred. For example, a polyvinyl alcohol film is subjected to iodine dyeing and stretching to obtain a PVA-based polarizer. As the PVA polarizer, a thin polarizer having a thickness of 10 mu m or less may be used. Examples of the thin polarizer include those described in Japanese Laid-Open Patent Publication No. 51-069644, Japanese Laid-Open Patent Publication No. 2000-338329, WO2010 / 100917, Japanese Patent No. 4691205, Japanese Patent No. 4751481 And a thin polarizing film. Such a thin polarizer can be obtained, for example, by a process comprising a step of stretching a PVA resin layer and a lead resin base material in a laminate state and a step of dyeing iodine.

As the transparent protective film 74, the same material as that described above is preferably used as the material of the transparent film 10. 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, , A fluorine-based polymer, a rubber-based polymer, or the like as a base polymer can be appropriately selected and used. For the adhesion of the PVA polarizer, a polyvinyl alcohol-based adhesive is preferably used.

4B shows a polarizing plate in which transparent protective films 73 and 74 are adhered to both surfaces of a polarizer 79 with adhesive layers 36 and 38 interposed therebetween and a polarizing plate in which an anti- Antireflection layer interposed therebetween. A release film 22 is attached to the surface of the transparent protective film 74 with an adhesive layer 39 interposed therebetween.

As the adhesive layer 35 used for bonding the transparent protective film 73 and the transparent film 10, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, or a silicone pressure- The adhesive layer 30 (diffusion adhesive) used for attaching the transparent film 10 and the film substrate 20 may be used as they are (see Figs. 3 (B) and (C1)).

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 apparatus, it is susceptible to contamination (fingerprints, fingers, dust, etc.) from the external environment. For the purpose of preventing pollution from the outside environment and facilitating removal of contamination, an antifouling layer composed of a fluorine group-containing silane compound or a fluorine group-containing organic compound may be formed on the surface of the antireflection layer.

10: Transparent film
20: Film substrate
30: adhesive layer (diffusion adhesive layer)
33, 35, 36, 38, 39: adhesive layer
40:
50: antireflection layer
51, 52, 53, 54: thin film
73, 74: transparent protective film
79: Polarizer
100, 101, 103: Antireflection film
111, and 112: an antireflection film (an optical film having an antireflection layer formed thereon)
121 and 122: antireflection film (polarizing plate having an antireflection layer)

Claims (10)

An antireflection film comprising an antireflection layer on a first main surface of a transparent film,
A laminate preparing step of preparing a laminate on the second main surface of the transparent film, the laminate being adhered to the film base so as to be removable via an adhesive layer;
An antireflection layer forming step of forming an antireflection layer made of two or more thin films on the first main surface of the transparent film of the laminate; And
An in-line inspection step of irradiating visible light from the formation surface side of the thin film after forming at least one layer of the thin film constituting the antireflection layer and detecting the reflected light,
The adhesive layer is a diffusion pressure-sensitive adhesive layer having a haze of 40% or more,
Wherein the antireflection layer forming step and the inline inspecting step are carried out continuously while conveying the laminate in one direction. The method according to claim 1,
Wherein in the inline inspection step, after forming all the plurality of thin films constituting the antireflection layer, visible light is irradiated from the formation surface side of the thin film and the reflected light is detected. 3. The method according to claim 1 or 2,
Wherein the film forming conditions of the thin film in the anti-reflection layer forming step are adjusted in accordance with the detection result of the reflected light in the inline inspection step. 4. The method according to any one of claims 1 to 3,
Further comprising a peeling step of peeling off the film base material from the transparent film after the inline inspection step. 5. The method of claim 4,
Wherein the film substrate is peeled off in a state in which the adhesive layer is attached to the transparent film in the peeling step. 5. The method of claim 4,
Wherein the adhesive layer is peeled from the transparent film together with the film base in the peeling step. 7. The method according to any one of claims 4 to 6,
And after the peeling step, an optical film is bonded onto the second main surface of the transparent film. 8. The method of claim 7,
Wherein the optical film is an optical film including a polarizer. An antireflection layer is provided on one surface of a transparent film, and a film base is adhered to the second main surface of the transparent film so as to be detachable via an adhesive layer,
Wherein the adhesive layer is a diffusion pressure-sensitive adhesive layer having a haze of 40% or more. A method for measuring a reflected light characteristic of an antireflection film having an antireflection layer composed of two or more thin films on a first main surface of a transparent film,
The reflected light of the visible light irradiated from the first main surface side is detected on the second main surface of the transparent film in a state in which the film base is adhered to the film substrate in such a manner that the film substrate can be peeled off via the adhesive layer,
The adhesive layer is a diffusion pressure-sensitive adhesive layer having a haze of 40% or more,
Wherein the detection of the reflected light is performed continuously while the anti-reflection film is transported in one direction.

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