JP7362860B1 - Manufacturing method of anti-reflection film - Google Patents

Abstract

An object of the present invention is to provide a method for producing an antireflection film that can suppress deformation of a film base material during production and obtain an antireflection film that has excellent high-temperature durability.
A method for manufacturing an antireflection film includes a step Sa and a step Sb. In step Sa, one main surface 12a of the film base material 13 is bombarded using rare gas and oxygen gas. In step Sb, an antireflection layer 19 is formed on the bombarded main surface 12a side. The antireflection layer 19 formed in step Sb is a multilayer film including a niobium oxide thin film and an inorganic thin film having a different refractive index from the niobium oxide thin film.
[Selection diagram] Figure 1

Description

The present invention relates to a method for manufacturing an antireflection film.

An antireflection film is disposed on the viewing side 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 and improving contrast. An antireflection film includes an antireflection layer formed of a laminate of a plurality of thin films having different refractive indexes on a film base material.

For example, in Patent Document 1, a SiO primer layer is provided on a film base material (hard coat film), and a niobium oxide (Nb 2 O 5 ) layer as a high refractive index layer and a niobium oxide (Nb ₂ O ₅ ) layer as a low refractive index layer are provided on the film base material (hard coat film). Antireflection films are disclosed that include antireflection layers consisting of alternating laminates with silicon oxide (SiO ₂ ) layers.

Further, Patent Document 1 describes a method for manufacturing a laminate having an antireflection layer and a polarizer made of the above-mentioned alternating laminate. Specifically, in Patent Document 1, an antireflection film is obtained by forming an SiO primer layer and an antireflection layer on a film base material that has been subjected to glow plasma treatment, and then this antireflection film and a polarizer, etc. The above-mentioned laminate is obtained by laminating the above. Hereinafter, a laminate having at least an antireflection layer and a polarizer may be referred to as an "antireflection film with a polarizer." The antireflection film with a polarizer can be used as a polarizing plate with an antireflection function.

JP2009-47876A

In general, antireflection films with polarizers used in in-vehicle image display devices have higher temperatures (e.g., 90°C or higher) than antireflection films with polarizers used in mobile devices intended for outdoor use. ) (particularly changes in appearance such as color unevenness) are required to be small. In other words, an antireflection film used in a vehicle-mounted image display device is required to be able to suppress changes in the film (for example, occurrence of color unevenness, etc.) at high temperatures when bonded to a polarizer. Hereinafter, the ability to suppress changes in the film at high temperatures when bonded to a polarizer may be referred to as "high temperature durability."

With the technique described in Patent Document 1, it is difficult to obtain an antireflection film that has excellent high-temperature durability while suppressing deformation of the film base material during production. Note that when the film base material is deformed, the transportability of the film decreases when manufacturing an antireflection film using a roll-to-roll method.

The present invention has been made in view of the above circumstances, and its purpose is to manufacture an antireflection film that can suppress deformation of the film base material during manufacturing and obtain an antireflection film that has excellent high temperature durability. The purpose is to provide a method.

<Aspects of the present invention>
The present invention includes the following aspects.

[1] A method for producing an antireflection film comprising a film base material and an antireflection layer provided on one main surface side of the film base material,
a step Sa of bombarding the one main surface of the film base material using a rare gas and oxygen gas;
step Sb of forming the antireflection layer on the main surface side subjected to the bombardment treatment,
The method for producing an antireflection film, wherein the antireflection layer is a multilayer film including a niobium oxide thin film and an inorganic thin film having a different refractive index from the niobium oxide thin film.

[2] The method for producing an antireflection film according to [1] above, wherein the rare gas is argon gas.

[3] In the step Sa, the ratio of the introduced amount of the oxygen gas to the total of the introduced amount of the rare gas and the oxygen gas is 0.0009 or more and 0.0500 or less, [1] Or the method for producing an antireflection film according to [2].

[4] The method for producing an antireflection film according to any one of [1] to [3] above, wherein in the step Sb, the antireflection layer is formed by a sputtering method.

[5] The method for producing an antireflection film according to any one of [1] to [4] above, wherein in the step Sa, bombardment treatment is performed under conditions of a pressure of 0.1 Pa or more and 1.0 Pa or less.

[6] The method for producing an antireflection film according to any one of [1] to [5] above, wherein the antireflection layer has a thickness of 100 nm or more and 300 nm or less.

[7] The film base material includes a transparent film and a hard coat layer provided on one main surface side of the transparent film,
The method for producing an antireflection film according to any one of [1] to [6], wherein in the step Sa, the main surface of the hard coat layer opposite to the transparent film side is bombarded.

[8] The method for producing an antireflection film according to [7], wherein the hard coat layer contains particles having a number average primary particle diameter of 0.5 μm or more.

[9] The method for producing an antireflection film according to [7] or [8], wherein the transparent film is a triacetyl cellulose film.

[10] After the step Sa and before the step Sb, further comprising a step Sc of forming a primer layer on the bombarded main surface side,
In the step Sb, the antireflection film according to any one of [1] to [9], wherein the antireflection layer is formed on the main surface of the primer layer opposite to the film base material side. manufacturing method.

According to the present invention, it is possible to provide a method for producing an antireflection film that can suppress deformation of the film base material during production and obtain an antireflection film that has excellent high-temperature durability.

A, B, C, and D are cross-sectional views showing each step of an example of the method for manufacturing an antireflection film according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of the antireflection film with a polarizer provided with the antireflection film obtained by the manufacturing method of this invention. It is a sectional view showing other examples of an antireflection film with a polarizer including an antireflection film obtained by the production method of the present invention.

Hereinafter, preferred embodiments of the present invention will be described. First, terms used in this specification will be explained. "Refractive index" is the refractive index for light with a wavelength of 550 nm in an atmosphere at a temperature of 23°C. The "principal surface" of a layered material (more specifically, a film base material, transparent film, hard coat layer, primer layer, adhesive layer, release liner, polarizer, etc.) is defined as the surface perpendicular to the thickness direction of the layered material. Rub the face. The thickness (film thickness) of each layer constituting the anti-reflection film is determined by randomly selecting 10 measurement points from a cross-sectional image of the layer cut in the thickness direction, and measuring the thickness of the 10 selected measurement points. This is the arithmetic mean value of the 10 measured values obtained.

"Bombard treatment" refers to surface treatment in which the surface of a film base material is subjected to plasma treatment while introducing a predetermined gas (rare gas, oxygen gas, etc.).

Unless otherwise specified, the particle number average primary particle diameter is a circle of 100 primary particles measured using a scanning electron microscope and image processing software (for example, "Image J" manufactured by the National Institutes of Health). This is the number average value of the equivalent diameter (Haywood diameter: diameter of a circle having the same area as the projected area of the primary particle).

"Moisture permeability" is the weight of water vapor that permeates through a sample with an area of 1 m ² in 24 hours at a temperature of 40° C. and a relative humidity difference of 90%, and is measured according to Annex B of JIS K7129:2008.

The flow rate unit "sccm (Standard Cubic Centimeter per Minute)" is the flow rate unit "mL/min" under standard conditions (temperature: 0° C., pressure: 101.3 kPa).

Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. Furthermore, when a polymer name is expressed by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative. The components, functional groups, etc. illustrated in this specification may be used alone, or two or more types may be used in combination, unless otherwise specified.

The drawings referred to in the following explanation mainly schematically show each component for ease of understanding. The above may differ from the actual one. Further, for convenience of explanation, in the drawings to be explained later, the same components as those in the drawings explained earlier may be denoted by the same reference numerals, and the explanation thereof may be omitted.

<Production method of anti-reflection film>
The method for manufacturing an antireflection film according to the present embodiment is a method for manufacturing an antireflection film (laminate) having a film base material and an antireflection layer provided on one main surface side of the film base material. , a step Sa, and a step Sb. In step Sa, one main surface of the film base material is subjected to bombardment treatment using a rare gas and oxygen gas. In step Sb, an antireflection layer is formed on the bombarded main surface side. Furthermore, in this embodiment, the antireflection layer formed in step Sb is a multilayer film including a niobium oxide thin film and an inorganic thin film having a different refractive index from the niobium oxide thin film.

According to the method for manufacturing an antireflection film according to the present embodiment, since the above structure is provided, an antireflection film having excellent high temperature durability can be manufactured while suppressing deformation of the film base material during manufacturing. Hereinafter, the process Sa may be referred to as a "bombardment process". Moreover, step Sb may be described as "an antireflection layer forming step."

The method for manufacturing an antireflection film according to the present embodiment may include steps (other steps) than the bombardment treatment step and the antireflection layer forming step. Other steps include, for example, a hard coat layer forming step, a primer layer forming step (step Sc), and the like, which will be described later.

Hereinafter, each process included in an example of the method for manufacturing an antireflection film according to the present embodiment will be described with reference to the drawings as appropriate. 1A, FIG. 1B, FIG. 1C, and FIG. 1D to be referred to are process-by-step cross-sectional views showing an example of the method for manufacturing the antireflection film according to the present embodiment.

[Hard coat layer formation process]
The hard coat layer forming step is a step of forming the hard coat layer 12 (see FIG. 1B) on one main surface 11a (see FIG. 1A) of the transparent film 11.

(Transparent film 11)
The transparent film 11 is, for example, a flexible transparent resin film. Examples of materials constituting the transparent film 11 include polyester resin, polyolefin resin, polystyrene resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyamide resin, polyimide resin, cellulose resin, norbornene resin, and polyarylate resin. , and polyvinyl alcohol resin. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of the cellulose resin include triacetylcellulose (TAC). These materials may be used alone or in combination of two or more. From the viewpoint of transparency and strength, the material for the transparent film 11 is preferably one selected from the group consisting of polyester resin, polyolefin resin, and cellulose resin, and one selected from the group consisting of PET, COP, and TAC. More preferred, TAC is even more preferred. That is, the transparent film 11 is preferably a type of film selected from the group consisting of a polyester resin film, a polyolefin resin film, and a cellulose resin film, and a type selected from the group consisting of a PET film, a COP film, and a TAC film. Films are more preferred, and TAC films are even more preferred.

When an anti-reflection film with a polarizer is formed, if the transparent film 11 has high moisture permeability, even if the anti-reflection film with a polarizer is placed in a heated environment, water in the polarizer will pass through the transparent film 11 to the outside. Since it is easily released into water, deterioration of the polarizer due to moisture can be suppressed. On the other hand, if the moisture permeability of the transparent film 11 is excessively high, the humidification durability of the antireflection film with a polarizer may decrease. Therefore, the moisture permeability of the transparent film 11 is preferably 2000 g/m ² ·24 h or less, more preferably 1500 g/m ² ·24 h or less. In order to keep the moisture permeability of the transparent film 11 within the above range, the transparent film 11 is preferably a cellulose resin film, and more preferably a TAC film.

From the viewpoint of strength, the thickness of the transparent film 11 is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 20 μm or more. From the viewpoint of handleability, the thickness of the transparent film 11 is preferably 300 μm or less, more preferably 200 μm or less.

One main surface or both main surfaces of the transparent film 11 may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

From the viewpoint of improving the transparency of the antireflection film, the total light transmittance (JIS K 7375-2008) of the transparent film 11 is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more and 100%. It is as follows.

(Hard coat layer 12)
The hard coat layer 12 is a layer that enhances mechanical properties such as hardness and elastic modulus of the antireflection film. The hard coat layer 12 is made of, for example, a cured product of a curable resin composition (composition for forming a hard coat layer). Examples of the curable resin contained in the curable resin composition include polyester resin, acrylic resin, urethane resin, urethane acrylate resin, amide resin, silicone resin, epoxy resin, and melamine resin. These curable resins may be used alone or in combination of two or more. From the viewpoint of increasing the hardness of the hard coat layer 12, the curable resin is preferably one or more selected from the group consisting of acrylic resins and urethane acrylate resins, and more preferably urethane acrylate resins.

Further, examples of the curable resin composition include an ultraviolet curable resin composition and a thermosetting resin composition. From the viewpoint of improving productivity of the antireflection film, the curable resin composition is preferably an ultraviolet curable resin composition. The ultraviolet curable resin composition contains one or more types selected from the group consisting of ultraviolet curable monomers, ultraviolet curable oligomers, and ultraviolet curable polymers. Specific examples of ultraviolet curable resin compositions include the hard coat layer forming composition described in JP-A No. 2016-179686.

Further, the curable resin composition may contain particles having a number average primary particle diameter of 0.5 μm or more (hereinafter sometimes referred to as “microparticles”). That is, the hard coat layer 12 may contain microparticles. By blending microparticles into the curable resin composition, it becomes possible to adjust the hardness, surface roughness, refractive index, and antiglare property of the hard coat layer 12. Examples of microparticles include metal (or metalloid) oxide particles, glass particles, and organic particles. Examples of the material for the metal (or metalloid) oxide particles include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of materials for the organic particles include polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate.

In order to easily adjust the antiglare properties of the hard coat layer 12, the number average primary particle size of the microparticles is preferably 1.0 μm or more and 5.0 μm or less, and preferably 2.0 μm or more and 4.0 μm or less. It is more preferable that there be.

In order to easily adjust the antiglare properties of the hard coat layer 12, the amount of microparticles in the hard coat layer 12 is preferably 5 parts by weight or more, and 10 parts by weight or more, based on 100 parts by weight of the curable resin. part or more, 20 parts by weight or more, or 30 parts by weight or more. The upper limit of the amount of microparticles in the hard coat layer 12 is, for example, 90 parts by weight, preferably 80 parts by weight, and may be 70 parts by weight, based on 100 parts by weight of the curable resin.

Further, the curable resin composition may contain particles having a number average primary particle diameter of less than 0.5 μm (hereinafter sometimes referred to as “nanoparticles”). When the hard coat layer 12 is made of a cured product of a curable resin composition containing nanoparticles, fine irregularities are formed on the surface of the hard coat layer 12, and the hard coat layer 12 and the layer formed thereon are adhesion tends to improve.

From the viewpoint of forming a fine uneven shape that contributes to improving adhesion, the number average primary particle diameter of the nanoparticles is preferably 20 nm or more and 80 nm or less, more preferably 25 nm or more and 70 nm or less, and 30 nm or more and 60 nm or less. It is more preferable that it is the following.

Inorganic oxides are preferred as materials for the nanoparticles. Examples of inorganic oxides include metal (or metalloid) oxides such as silicon oxide (silica), titanium oxide, aluminum oxide, zirconium oxide, niobium oxide, zinc oxide, tin oxide, cerium oxide, and magnesium oxide. The inorganic oxide may be a composite oxide of multiple types of (semi-)metals. Among the exemplified inorganic oxides, silicon oxide is preferred because it has a high effect of improving adhesion. That is, as the nanoparticles, silicon oxide particles (silica particles) are preferable. A functional group such as an acrylic group or an epoxy group may be introduced into the surface of the inorganic oxide particle as a nanoparticle for the purpose of increasing adhesion or affinity with the resin.

The amount of nanoparticles in the hard coat layer 12 is preferably 5 parts by weight or more, and may be 10 parts by weight or more, 20 parts by weight or more, or 30 parts by weight or more based on 100 parts by weight of the curable resin. . If the amount of nanoparticles is 5 parts by weight or more, the adhesion to the layer formed on the hard coat layer 12 can be further improved. The upper limit of the amount of nanoparticles in the hard coat layer 12 is, for example, 90 parts by weight, preferably 80 parts by weight, and may be 70 parts by weight, based on 100 parts by weight of the curable resin.

The curable resin composition (composition for forming a hard coat layer) contains, for example, the above-mentioned curable resin and a polymerization initiator (for example, a photopolymerization initiator), and these components can be dissolved or dispersed as necessary. Contains solvents. In addition to the above-mentioned components, the curable resin composition (composition for forming a hard coat layer) includes microparticles, nanoparticles, leveling agents, viscosity modifiers (thixotropic agents, thickeners, etc.), antistatic agents, It may contain additives such as antiblocking agents, dispersants, dispersion stabilizers, antioxidants, ultraviolet absorbers, antifoaming agents, surfactants, and lubricants.

From the viewpoint of increasing the hardness of the hard coat layer 12, the thickness of the hard coat layer 12 is preferably 1 μm or more, more preferably 2 μm or more. From the viewpoint of ensuring flexibility of the antireflection film, the thickness of the hard coat layer 12 is preferably 50 μm or less, more preferably 40 μm or less, still more preferably 35 μm or less, and even more preferably 30 μm or less.

(Method for forming hard coat layer 12)
The hard coat layer 12 is formed, for example, by applying a curable resin composition (composition for forming a hard coat layer) to one main surface 11a (see FIG. 1A) of the transparent film 11, and removing the solvent and removing the solvent as necessary. It is formed by curing the resin. By providing the hard coat layer 12 on one main surface 11a of the transparent film 11, a film base material 13 including the transparent film 11 and the hard coat layer 12 is obtained, as shown in FIG. 1B.

The hard coat layer forming composition can be applied by any suitable method such as bar coating, roll coating, gravure coating, rod coating, slot orifice coating, curtain coating, fountain coating, comma coating, etc. method can be adopted. The drying temperature of the coating film after application may be set to an appropriate temperature depending on the composition of the composition for forming a hard coat layer, and is, for example, 50° C. or higher and 150° C. or lower. When the resin component in the composition for forming a hard coat layer is a thermosetting resin, the coating film is cured by heating. When the resin component in the composition for forming a hard coat layer is a photocurable resin, the coating film is cured by irradiation with active energy rays such as ultraviolet rays. The cumulative amount of irradiation light is preferably 100 mJ/cm ² or more and 500 mJ/cm ² or less.

[Bombarding process]
In the bombardment process, one main surface of the film base material 13 (in FIG. 1B, the main surface 12a on the opposite side of the hard coat layer 12 to the transparent film 11 side) is bombarded using rare gas and oxygen gas. . As a result of the bombardment process, one main surface of the film base material 13 becomes uneven. Due to the uneven shape of the film base material 13, for example, the columnar growth of the sputtered film formed on the film base material 13 is promoted, and as a result, the antireflection layer 19 (see FIG. 1D) with high moisture permeability is formed. It is assumed that it can be formed.

When an antireflection film with a polarizer is formed, if the moisture permeability of the antireflection layer 19 is high, even if the antireflection film with a polarizer is placed in a heated environment, water in the polarizer will not pass through the antireflection layer 19. Since the polarizer is easily released to the outside, deterioration of the polarizer due to moisture (for example, occurrence of color unevenness, etc.) can be suppressed. Therefore, by increasing the moisture permeability of the antireflection layer 19, an antireflection film with excellent high-temperature durability can be obtained.

Generally, when an antireflection film with a polarizer is exposed to a heated environment, water in the transparent film and the polarizer evaporates out of the film. When the moisture permeability of the antireflection layer is low, it is difficult for moisture to diffuse out of the system. When moisture remains inside the film, for example, triacetylcellulose and the like that constitute the transparent film are likely to be hydrolyzed, and the protective performance of the polarizer tends to decrease. Furthermore, when triacetylcellulose is hydrolyzed, free acids are generated. In the presence of acid, the polyvinyl alcohol constituting the polarizer is likely to undergo polyenization, which causes deterioration of the polarizer. On the other hand, when the moisture permeability of the anti-reflection layer is high, the moisture evaporated from the polarizer or transparent film is likely to diffuse out of the system from the surface of the anti-reflection layer, suppressing the retention of moisture and causing high temperatures. It is thought that the deterioration of the antireflection film with a polarizer is suppressed.

Examples of the rare gas used in the bombardment process include argon gas, krypton gas, and xenon gas. In order to obtain the antireflection layer 19 with higher moisture permeability, argon gas is preferable as the rare gas.

In order to obtain the antireflection layer 19 with higher moisture permeability, the amount (flow rate) of rare gas introduced in the bombardment process is preferably 800 sccm or more and 1200 sccm or less, and more preferably 900 sccm or more and 1100 sccm or less. In order to obtain the antireflection layer 19 with higher moisture permeability, the amount (flow rate) of oxygen gas introduced in the bombardment process is preferably 0.1 sccm or more and 200 sccm or less, and 0.5 sccm or more and 100 sccm or less. It is more preferable that there be.

In order to obtain the antireflection layer 19 with higher moisture permeability, the ratio of the amount of oxygen gas introduced (flow rate ratio) to the total amount of introduced rare gas and oxygen gas is 0.0009 or more and 0.0500. It is preferable that it is below. Hereinafter, the ratio of the introduction amounts (flow rate ratio), ie, "oxygen gas introduction amount/(rare gas introduction amount + oxygen gas introduction amount)" may be referred to as "oxygen gas introduction ratio."

In order to obtain an antireflection layer 19 with higher moisture permeability, it is preferable to bombard one main surface of the film base material 13 under conditions of a pressure of 0.1 Pa or more and 1.0 Pa or less, and a pressure of 0.3 Pa or more. It is more preferable to bombard one main surface of the film base material 13 under conditions of 0.8 Pa or less.

In order to obtain the antireflection layer 19 with higher moisture permeability, the effective power density in the bombardment process is preferably 0.01 W·min/cm ² ·m or more, and 0.02 W·min/cm ² ·m. It is more preferable that it is 0.03 W·min/cm ² ·m or more, and even more preferably that it is 0.03 W·min/cm 2·m or more. In order to further suppress deformation of the film base material 13 during manufacturing (bombardment process), the effective power density in the bombardment process is preferably 0.60 W·min/cm ² ·m or less; It is more preferable that it is 55W・min/cm ²・m or less, even more preferably that it is 0.50W・min/cm ²・m or less, and even more preferably that it is 0.45W・min/cm ²・m or less. More preferably, it is 0.40 W·min/cm ² ·m or less, particularly preferably 0.35 W·min/cm ² ·m or less. Note that the effective power density is a value obtained by dividing the power density (W/cm ² ) of the plasma output by the film conveyance speed (m/min) by the roll-to-roll method. Even if the plasma output is the same, if the transport speed is high, the effective processing power will decrease.

In this embodiment, since the bombardment process is performed using rare gas and oxygen gas, the moisture permeability of the antireflection layer 19 can be increased even if the effective power density is reduced. Therefore, according to the manufacturing method of this embodiment, it is possible to obtain an antireflection film that has excellent high-temperature durability while suppressing deformation of the film base material 13 during manufacturing.

In order to obtain an antireflection layer 19 with higher moisture permeability, the arithmetic mean roughness Ra of one main surface of the bombarded film base 13 is preferably 0.30 nm or more and 0.70 nm or less, More preferably, the thickness is 0.40 nm or more and 0.60 nm or less. The arithmetic mean roughness Ra of one main surface of the film base material 13 can be determined by observing the main surface using an atomic force microscope (AFM) and from an observed image of 1 μm square. The arithmetic mean roughness Ra of one main surface of the film base material 13 can be adjusted by changing the conditions of the bombardment process (specifically, effective power density, oxygen gas introduction ratio, etc.).

[Primer layer formation process]
In the primer layer forming step, a primer layer 14 (in FIG. 1B, the main surface 12a side of the hard coat layer 12 opposite to the transparent film 11 side in FIG. 1B) is formed on one main surface side of the bombarded film base material 13. 1C)).

Providing the primer layer 14 increases the adhesion between the film base material 13 and the antireflection layer 19. Materials for the primer layer 14 include metals (or semimetals) such as silicon, nickel, chromium, tin, gold, silver, platinum, zinc, titanium, indium, tungsten, aluminum, zirconium, and palladium; alloys of metals); oxides, fluorides, sulfides, nitrides, etc. of these metals (or semimetals). The oxide constituting the primer layer 14 may be a composite oxide such as indium tin oxide (ITO). Among these, the material for the primer layer 14 is preferably an inorganic oxide, more preferably silicon oxide, indium oxide, or ITO, and even more preferably SiOx (x<2).

In order to ensure the light transmittance of the primer layer 14 while increasing the adhesion between the film base material 13 and the antireflection layer 19, the thickness of the primer layer 14 is preferably 0.5 nm or more and 20 nm or less, It is more preferably 0.5 nm or more and 10 nm or less, and even more preferably 1.0 nm or more and 10 nm or less.

The method for forming the primer layer 14 is not particularly limited, and may be either a wet coating method or a dry coating method. Dry coating methods such as vacuum evaporation, CVD, and sputtering are preferred, and sputtering is more preferred, since a thin film with uniform thickness can be formed. From the viewpoint of increasing productivity, a method of forming the primer layer 14 using a roll-to-roll sputtering film forming apparatus (roll-to-roll sputtering method) is preferable.

In the roll-to-roll sputtering method, for example, the primer layer 14 and the antireflection layer 19 can be continuously formed while conveying the long film base material 13 in the longitudinal direction (MD direction). In the sputtering method, film formation is performed while introducing an inert gas such as argon and, if necessary, a reactive gas such as oxygen into a film forming chamber. When forming an oxide film as the primer layer 14, the oxide film can be formed by sputtering by either a method using an oxide target or a reactive sputtering method using a metal (or semimetal) target. .

When an oxide target is used to form a film of an insulating oxide such as silicon oxide, RF discharge is required, so the film formation rate tends to be low and productivity tends to be low. Therefore, reactive sputtering using a metal target is preferable for forming the oxide film by sputtering. In the reactive sputtering method, film formation is performed while introducing an inert gas such as argon and a reactive gas such as oxygen into a film forming chamber. In the reactive sputtering method, it is preferable to adjust the amount of oxygen so that the transition region is intermediate between the metal region and the oxide region. If film formation is performed in a metal region where the amount of oxygen is insufficient, the amount of oxygen in the resulting oxide film will be significantly smaller than the stoichiometric composition, and the oxide film will take on a metallic luster and its transparency will decrease. There is a tendency to Further, in an oxide region with a large amount of oxygen, the film formation rate tends to be extremely low. By adjusting the amount of oxygen so that the sputtering film is formed in the transition region, an oxide film can be formed at a high rate. Further, by forming a film in the transition region, the moisture permeability of the resulting film increases, and as a result, the high temperature durability of the antireflection film tends to improve. The sputtering power source used in the reactive sputtering method is preferably a DC power source or a MFAC power source (AC power source with a frequency band of several kHz to several MHz).

In reactive sputtering, a method for controlling the amount of oxygen introduced so that the film formation mode is in the transition region is plasma emission monitoring, which detects the plasma emission intensity of the discharge and controls the amount of gas introduced into the film formation chamber. (PEM method). In the PEM method, control is performed by detecting the plasma emission intensity and feeding it back to the amount of oxygen introduced. For example, film formation in the transition region can be maintained by performing PEM control by setting the control value (set point) of the emission intensity within a predetermined range and adjusting the amount of oxygen introduced. Alternatively, control may be performed by a method (impedance method) in which the amount of oxygen introduced is controlled so that the plasma impedance is constant, that is, the discharge voltage is constant.

If the amount of oxygen introduced is controlled by the PEM method or the impedance method, the film formation rate in continuous thin film formation by the roll-to-roll method can be kept constant in the longitudinal direction. Therefore, the thickness of the thin film becomes uniform, and an antireflection film with excellent antireflection properties can be obtained. By providing a plurality of oxygen introduction pipes in the width direction and individually controlling the flow rate of oxygen introduced from each pipe, the uniformity of quality in the width direction can also be improved.

The power density when performing the sputtering method is, for example, 0.1 W/cm ² or more and 20 W/cm ² or less, preferably 1 W/cm ² or more and 15 W/cm ² or less. The surface temperature of the film forming roll when performing the sputtering method is, for example, -25°C or more and 25°C or less, preferably -20°C or more and 0°C or less. The pressure in the film forming chamber when performing the sputtering method is, for example, 0.01 Pa or more and 10 Pa or less, preferably 0.1 Pa or more and 1.0 Pa or less.

[Anti-reflection layer forming process]
In the antireflection layer forming step, an antireflection layer 19 is formed on one main surface side of the bombarded film base material 13 (in FIG. 1C, the main surface 14a on the opposite side to the film base material 13 side of the primer layer 14). This is a process of forming a film.

The antireflection layer 19 is a multilayer film including a niobium oxide thin film and an inorganic thin film having a different refractive index from the niobium oxide thin film. The antireflection layer 19 shown in FIG. 1D has four layers in this order: a high refractive index layer 15, a low refractive index layer 16, a high refractive index layer 17, and a low refractive index layer 18 from the primer layer 14 side. Among these, it is preferable that at least one of the high refractive index layer 15 and the high refractive index layer 17 is a niobium oxide thin film, and that both the high refractive index layer 15 and the high refractive index layer 17 are niobium oxide thin films. When both the high refractive index layer 15 and the high refractive index layer 17 are niobium oxide thin films, the low refractive index layer 16 and the low refractive index layer 18 are inorganic thin films having a lower refractive index than the niobium oxide thin film. Details of the high refractive index layer and the low refractive index layer will be described later. Note that the antireflection layer of the antireflection film is not limited to a four-layer structure like the antireflection layer 19, but may have a two-layer structure, a three-layer structure, a five-layer structure, or a laminated structure of six or more layers. . In order to reduce reflection at the air interface, the outermost layer (the layer farthest from the film base material) of the antireflection layer of the antireflection film is preferably a low refractive index layer.

Generally, the optical thickness (product of refractive index and thickness) of the thin film of the antireflection layer is adjusted so that the reversed phases of incident light and reflected light cancel each other out. By making the antireflection layer a multilayer laminate of two or more thin films with different refractive indexes, the reflectance can be reduced in a wide wavelength range of visible light.

Examples of the material of the thin film constituting the antireflection layer 19 include metal (or semimetal) oxides, nitrides, and fluorides. The antireflection layer 19 is preferably an alternating laminate of high refractive index layers and low refractive index layers, more preferably an alternating laminate of two or more high refractive index layers and two or more low refractive index layers. It is the body.

The high refractive index layer has a refractive index of, for example, 1.9 or more, preferably 2.0 or more. Examples of the material for the high refractive index layer include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, ITO, and antimony-doped tin oxide (ATO). Among these, one or more selected from the group consisting of titanium oxide and niobium oxide are preferred. The low refractive index layer has a refractive index of, for example, 1.6 or less, preferably 1.5 or less. Examples of the material for the low refractive index layer include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, and lanthanum fluoride. Among them, silicon oxide is preferred. In particular, it is preferable to alternately laminate niobium oxide (Nb ₂ O ₅ ) thin films as high refractive index layers and silicon oxide (SiO ₂ ) thin films as low refractive index layers. In addition to the low refractive index layer and the high refractive index layer, a medium refractive index layer having a refractive index of more than 1.6 and less than 1.9 may be provided.

The film thickness of the high refractive index layer and the low refractive index layer is preferably 5 nm or more and 200 nm or less, and more preferably 10 nm or more and 150 nm or less. The film thickness of each layer may be designed in accordance with the refractive index, laminated structure, etc. so that the reflectance of visible light is small. For example, the laminated structure of a high refractive index layer and a low refractive index layer includes, from the film base material 13 side, a high refractive index layer with an optical thickness of 20 nm or more and 55 nm or less, a low refractive index layer with an optical thickness of 35 nm or more and 60 nm or less, A four-layer structure consisting of a high refractive index layer with an optical thickness of 65 nm or more and 250 nm or less, and a low refractive index layer with an optical thickness of 100 nm or more and 150 nm or less is exemplified.

The antireflection layer 19 is a four-layer alternating laminate in which niobium oxide (Nb ₂ O ₅ ) thin films as high refractive index layers and silicon oxide (SiO ₂ ) thin films as low refractive index layers are alternately laminated. In this case, the structure of the antireflection layer 19 includes, from the film base material 13 side, a niobium oxide thin film with a thickness of 5 nm or more and 20 nm or less, a silicon oxide thin film with a thickness of 20 nm or more and 60 nm or less, a niobium oxide thin film with a thickness of 25 nm or more and 120 nm or less, and a silicon oxide thin film with a thickness of 50 nm or more and 100 nm or less in this order.

In order to obtain an antireflection film with better high-temperature durability, the thickness of the antireflection layer 19 is preferably 100 nm or more and 300 nm or less, more preferably 120 nm or more and 280 nm or less, and 140 nm or more and 260 nm or less. is more preferable, and even more preferably 160 nm or more and 240 nm or less. In addition, in this specification, "the thickness of an antireflection layer" is the sum total (total thickness) of the thickness of each layer which comprises an antireflection layer.

The method for forming the antireflection layer 19 is not particularly limited, and may be either a wet coating method or a dry coating method. Dry coating methods such as vacuum evaporation, CVD, and sputtering are preferred, and sputtering is more preferred, since a thin film with uniform thickness can be formed. From the viewpoint of increasing productivity, a method of forming the antireflection layer 19 using a roll-to-roll sputtering film forming apparatus (roll-to-roll sputtering method) is preferable.

When forming the antireflection layer 19 shown in FIG. 1D by sputtering, a high refractive index layer 15, a low refractive index layer 16, a high refractive index layer 16, a high refractive index layer 16, a high refractive index layer 16, Four layers, the index layer 17 and the low refractive index layer 18, are formed in this order. Among these, at least one of the high refractive index layer 15 and the high refractive index layer 17 is a niobium oxide thin film. By forming the antireflection layer 19 on the main surface 14a of the primer layer 14 on the opposite side to the film base material 13 side, the antireflection film 10 shown in FIG. 1D is obtained. When forming the antireflection layer 19 by sputtering, the film forming conditions can be set as appropriate, for example, among the conditions described in the above-mentioned [Primer layer forming step].

The inventors have found that the effect of increasing the moisture permeability of the antireflection layer 19 by bombardment treatment using a combination of rare gas and oxygen gas is noticeable when forming the antireflection layer 19 containing a niobium oxide thin film. There was found. The moisture permeability of the antireflection layer 19 can be adjusted by changing the conditions of the bombardment process described above (specifically, effective power density, oxygen gas introduction ratio, etc.).

The moisture permeability of the antireflection layer 19 is preferably 15 g/m ² ·24 h or more, more preferably 20 g/m ² ·24 h or more, and even more preferably 30 g/m ² ·24 h or more. By increasing the moisture permeability of the antireflection layer 19, retention of moisture is suppressed, and an antireflection film with excellent high-temperature durability can be obtained. If the moisture permeability of the antireflection layer 19 is too high, the durability under high humidity tends to decrease. Therefore, the moisture permeability of the antireflection layer 19 is preferably 1000 g/m ² ·24 h or less, and 800 g/m ² - 24 hours or less is more preferable.

Note that the antireflection layer 19 is a thin film, and it is difficult to determine the moisture permeability of the antireflection layer 19 alone. However, the moisture permeability of many resin films is sufficiently higher than that of inorganic oxide films, so the moisture permeability of the antireflection film provided with the antireflection layer 19 is equal to the moisture permeability of the antireflection layer 19. It can be considered as

[Anti-reflection film with polarizer]
Next, an antireflection film with a polarizer including an antireflection film obtained by the above-described manufacturing method will be described. FIG. 2 is a cross-sectional view showing an example of the antireflection film with a polarizer.

In the antireflection film 100 with a polarizer shown in FIG. 2, one main surface of the polarizer 50 is bonded to the main surface 11b of the transparent film 11 on the side opposite to the antireflection layer 19 side. A transparent protective film 51 is attached to the other main surface of the polarizer 50.

The polarizer 50 is a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, a partially saponified ethylene/vinyl acetate copolymer film, or a dichroic film such as iodine or a dichroic dye. Examples include polyene-based oriented films such as those obtained by adsorbing a substance and uniaxially stretched, polyvinyl alcohol dehydrated, and polyvinyl chloride dehydrochlorinated. Among them, because it has a high degree of polarization, polyvinyl alcohol or polyvinyl alcohol film such as partially formalized polyvinyl alcohol is made by adsorbing a dichroic substance such as iodine or dichroic dye and oriented in a predetermined direction. Alcohol (PVA) based polarizers are preferred. The thickness of the polarizer 50 is, for example, 5 μm or more and 100 μm or less.

As the material for the transparent protective film 51, the same material as that described above for the transparent film 11 is preferably used. Further, the preferred thickness range of the transparent protective film 51 is also the same as the preferred thickness range of the transparent film 11 described above. Note that the material of the transparent protective film 51 and the material of the transparent film 11 may be the same or different. Further, the thickness of the transparent protective film 51 and the thickness of the transparent film 11 may be the same or different.

It is preferable to use an adhesive for bonding the polarizer 50 and the transparent film 11 and for bonding the polarizer 50 and the transparent protective film 51 together. Adhesives based on acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl alcohol, polyvinyl ether, vinyl acetate/vinyl chloride copolymer, modified polyolefin, epoxy polymer, fluorine polymer, rubber polymer, etc. A suitable polymer can be selected and used. A polyvinyl alcohol adhesive is preferably used for adhering the PVA polarizer.

Note that the antireflection film with a polarizer including the antireflection film obtained by the above-described manufacturing method is not limited to the antireflection film with a polarizer 100 shown in FIG. 2. For example, the antireflection film with a polarizer is, as shown in FIG. There may be.

The adhesive constituting the adhesive layer 201 is not particularly limited, and includes, for example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate-vinyl chloride copolymer, modified polyolefin, and epoxy resin. , a transparent adhesive having a base polymer such as fluororesin, natural rubber, or synthetic rubber can be appropriately selected and used. The thickness of the adhesive layer 201 is not particularly limited, but from the viewpoint of achieving both thin layer property and adhesive property, it is preferably 5 μm or more and 100 μm or less.

A release liner (not shown) may be temporarily attached to the main surface of the adhesive layer 201 on the side opposite to the transparent protective film 51 side. The release liner protects the surface of the adhesive layer 201, for example, until the polarizer-equipped antireflection film 200 is bonded to an image display cell (not shown). As the constituent material of the release liner, a plastic film made of acrylic, polyolefin, cyclic polyolefin, polyester, etc. is suitably used. The thickness of the release liner is, for example, 5 μm or more and 200 μm or less. The surface of the release liner is preferably subjected to a release treatment. Materials for the mold release agent used in the mold release treatment include silicone materials, fluorine materials, long chain alkyl materials, fatty acid amide materials, and the like.

The antireflection film obtained by the manufacturing method according to the present embodiment is used, for example, in displays such as liquid crystal display devices and organic EL display devices. In particular, when used as the outermost layer of a display, the visibility of the display is improved due to antireflection. The antireflection film obtained by the manufacturing method according to the present embodiment and the antireflection film with a polarizer using the same are resistant to deterioration even when exposed to a high temperature environment for a long time and have excellent high temperature durability, so they can be used in vehicles. It is particularly suitable for use in displays and the like.

[Preferred embodiment of the method for producing an antireflection film]
In order to obtain an antireflection film that has even better high-temperature durability while further suppressing deformation of the film base material during production, the method for producing an antireflection film according to the present embodiment preferably satisfies Condition 1 below. , it is more preferable that the following condition 2 is satisfied, and it is even more preferable that the following condition 3 is satisfied.
Condition 1: One main surface of the film base material is subjected to bombardment treatment under the conditions that the oxygen gas introduction ratio is 0.0009 or more and 0.0500 or less, and the pressure is 0.1 Pa or more and 1.0 Pa or less.
Condition 2: Condition 1 above is satisfied, and the thickness of the antireflection layer to be formed is 100 nm or more and 300 nm or less.
Condition 3: Condition 2 above is satisfied, and the effective power density in the bombardment process is 0.01 W·min/cm ² ·m or more and 0.60 W·min/cm ² ·m or less.

Although the method for manufacturing an antireflection film according to the present embodiment has been described above, the present invention is not limited to the above-described embodiment. For example, the method for producing an antireflection film according to the present invention does not need to include the hard coat layer forming step and the primer layer forming step. When the hard coat layer forming step is not performed in the present invention, for example, a transparent film can be used as the film base material. Further, the method for producing an antireflection film according to the present invention may include a step of forming an antifouling layer after the antireflection layer forming step. As the material for the antifouling layer, fluorine-containing compounds are preferred.

Further, in the present invention, after a polarizer and a transparent protective film are bonded to the laminate shown in FIG. 1B, an antireflection layer or the like may be formed by sputtering. In addition, in the present invention, a polarizer and a transparent protective film are bonded to the laminate shown in FIG. You may. That is, the method for manufacturing an antireflection film of the present invention may be a method for manufacturing an antireflection film with a polarizer.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

<Production of antireflection film with polarizer>
The method for producing the antireflection films with polarizers of Examples 1 to 5 will be described below.

[Example 1]
(Hard coat layer formation process)
100 parts by weight of ultraviolet curable urethane acrylate monomer (refractive index: 1.51), 14 parts by weight of polystyrene beads (refractive index: 1.59, number average primary particle diameter: 3.0 μm), and 5 parts by weight. The alkylphenone photopolymerization initiator, 135 parts by weight of toluene, and 10 parts by weight of ethyl acetate were mixed to prepare a composition for forming a hard coat layer having a solid content concentration of 45% by weight. Next, the hard coat layer forming composition was applied to one main surface of a TAC film (thickness: 80 μm, refractive index: 1.49) as a transparent film to form a coating film. Next, the coating film was dried by heating at a temperature of 80° C. for 2 minutes, and then cured by ultraviolet irradiation. Thereby, an antiglare hard coat layer (hard coat layer having an uneven structure on the surface) having a thickness of 5 μm was formed on one main surface of the TAC film, and a transparent film with a hard coat layer was obtained.

(Production process of polarizing plate)
A TAC film, which is the transparent film with a hard coat layer, is pasted on one main surface of a separately prepared polarizer, and a separately prepared TAC film (thickness: 80 μm, refractive index: 1. 49) were bonded together to produce a polarizing plate. As the polarizer, a PVA-based polarizer was used, which was made by stretching a polyvinyl alcohol film having an average degree of polymerization of 2,700 and a thickness of 75 μm six times while dyeing with iodine. In addition, for bonding (adhesion) between the PVA polarizer and the TAC film, a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: After bonding with a roll bonding machine using an adhesive consisting of an aqueous solution containing 5 mol %) and methylolmelamine in a weight ratio of 3:1, they were heated and dried in an oven.

(Production process of polarizing plate with adhesive layer)
Separately prepare a release liner (PET film treated with a silicone release agent) with a thickness of 38 μm, apply an acrylic adhesive to one main surface of the release liner, and then dry at a temperature of 120°C for 2 minutes. In this way, an adhesive layer was formed on one main surface of the release liner. Next, the obtained adhesive layer and the TAC film of the polarizing plate (specifically, the TAC film not in contact with the hard coat layer) are bonded together to form a polarizing plate with an adhesive layer (film base material). Obtained.

(Bombarding process)
Using a roll-to-roll type plasma processing device, the adhesive layer-coated polarizing plate is conveyed under conditions of a pressure of 0.6 Pa and an effective power density of 0.34 W min/cm ² m. The main surface of the hard coat layer of the board (specifically, the main surface of the hard coat layer on the side opposite to the TAC film side) was subjected to bombardment treatment. During the bombardment process, argon gas (flow rate: 1049 sccm) and oxygen gas (flow rate: 1 sccm) were introduced into the apparatus. Hereinafter, the polarizing plate with an adhesive layer after bombardment treatment may be referred to as "optical film F1".

Next, the primer layer forming step and the antireflection layer forming step will be explained. In addition, in the primer layer forming step and the antireflection layer forming step, when forming (film forming) the oxide film, the film was formed while introducing argon gas and oxygen gas into the film forming chamber. In addition, when forming an oxide film, the pressure is kept constant by adjusting the amount of argon gas introduced and exhausted, and the film formation mode is controlled to be in the transition region by plasma emission monitoring (PEM) control. The amount of oxygen gas introduced was adjusted to maintain the following.

(Primer layer formation process)
The obtained optical film F1 was introduced into a roll-to-roll type sputtering film forming apparatus, and the pressure inside the film forming chamber was reduced to 1×10 ⁻⁴ Pa. Next, while conveying the optical film F1, the surface temperature of the film forming roll was set to -8°C, and a 3.5 nm thick SiOx layer (x <2) was formed (film formed). A Si target was used as a target material to form the primer layer. When forming a film by reactive sputtering, the power source was an MFAC power source (frequency: 40 kHz), the power density was 3 W/cm ² , and the pressure inside the film forming chamber was 0.4 Pa.

(Anti-reflection layer formation process)
Following the formation of the primer layer, while conveying the optical film F1 on which the primer layer has been formed using a roll-to-roll sputtering film forming apparatus, a first layer is deposited on one main surface of the primer layer by reactive sputtering. Layer: ₅ layers of Nb ₂ O with a thickness of 12 nm (refractive index: 2.33), 2nd layer: ₂ layers of SiO with a thickness of 28 nm (refractive index: 1.46), 3rd layer: ₅ layers of Nb ₂ O with a thickness of 100 nm , and fourth layer: 85 nm thick SiO ₂ layer were formed in this order. As a result, an antireflection layer having a four-layer structure (a four-layer structure consisting of a first layer, a second layer, a third layer, and a fourth layer) is formed on one main surface of the primer layer, and the polarized light of Example 1 is An antireflection film with particles was obtained. In the deposition of each of the first to fourth layers, the surface temperature of the film-forming roll was -8° C., and the power source was an MFAC power source (frequency: 40 kHz). Furthermore, in the deposition of the first layer and the third layer, a Nb target was used, the power density was 13 W/cm ² , and the pressure inside the deposition chamber was 0.5 Pa. Further, in forming the second layer and the fourth layer, a Si target was used, the power density was 8 W/cm ² , and the pressure inside the film forming chamber was 0.5 Pa.

[Examples 2 to 5]
The antireflection films with polarizers of Examples 2 to 5 were manufactured using the same manufacturing method as Example 1, except that the flow rates of argon gas and oxygen gas in the bombardment process were as shown in Table 1 below. I got each.

<Production of reference example of antireflection film with polarizer>
Next, as films according to Reference Examples 1 to 5, methods for producing films of Reference Examples 1 to 15 will be described.

[Reference example 1]
Same manufacturing method as Example 1 except that the primer layer formation step was not performed and a single layer of Nb ₂ O ₅ (thickness: 100 nm) was formed as the antireflection layer in the antireflection layer formation step. Thus, a film of Reference Example 1 was obtained. Note that the film-forming conditions for the antireflection layer (Nb ₂ O ₅ layers) of Reference Example 1 were the same as the film-forming conditions for the third layer of Example 1.

[Reference Examples 2 to 5 and 11]
Films of Reference Examples 2 to 5 and 11 were obtained by the same production method as Reference Example 1, except that the flow rates of argon gas and oxygen gas in the bombardment process were as shown in Table 1 below. .

[Reference example 6]
The same manufacturing method as in Example 1 was used, except that the primer layer formation step was not carried out, and in the antireflection layer formation step, a single SiO ₂ layer (thickness: 85 nm) was formed as the antireflection layer. A film of Reference Example 6 was obtained. Note that the film-forming conditions for the antireflection layer (SiO ₂ layer) in Reference Example 6 were the same as the film-forming conditions for the fourth layer in Example 1.

[Reference Examples 7 to 10 and 12]
Films of Reference Examples 7 to 10 and 12 were obtained by the same production method as Reference Example 6, except that the flow rates of argon gas and oxygen gas in the bombardment process were as shown in Table 1 below. .

[Reference Examples 13 to 15]
Example 1 except that the flow rates of argon gas and oxygen gas in the bombardment process were as shown in Table 1 below, and that the primer layer formation process and antireflection layer formation process were not performed. Films of Reference Examples 13 to 15 were obtained using the same production method.

<Evaluation method for Examples 1 to 5 and Reference Examples 1 to 15>
Hereinafter, methods for evaluating the antireflection films with polarizers of Examples 1 to 5 and the films of Reference Examples 1 to 15 (hereinafter, each of these may be referred to as "evaluation target film S1") will be described.

[Moisture permeability]
According to Annex B of JIS K7129:2008, the moisture permeability of the evaluation target film S1 from which the PET film was peeled was measured in an atmosphere at a temperature of 40° C. and a relative humidity of 90%.

[Evaluation of high temperature durability]
First, a heating test was conducted on the film S1 to be evaluated. Specifically, the evaluation target film S1 was placed in a hot air oven at a temperature of 95° C. and taken out after 1000 hours. Next, a commercially available polarizing plate is placed on the backlight, and the evaluation target film S1 after the heating test is placed on it in a crossed nicol state, and the appearance of the evaluation target film S1 is visually checked to see if there is any change. It was confirmed. Items with no change in appearance before and after the heating test are rated A (excellent in high-temperature durability), and items with a change in appearance before and after the heating test are rated B (not excellent in high-temperature durability). ).

[Presence or absence of wrinkles]
When producing the evaluation target film S1, the film base material after the bombardment treatment step was visually observed to confirm the presence or absence of wrinkles on the film base material. If there were no wrinkles, it was evaluated as ``the deformation of the film base material during manufacturing was suppressed,'' and if there were wrinkles, it was evaluated as ``the deformation of the film base material during manufacturing was not suppressed.'' .

<Evaluation results of Examples 1 to 5 and Reference Examples 1 to 15>
Regarding Examples 1 to 5 and Reference Examples 1 to 15, evaluation of the flow rate of argon gas and the flow rate of oxygen gas in the bombardment process, the oxygen gas introduction ratio in the bombardment process, the structure of the antireflection layer, moisture permeability, and high temperature durability. Table 1 shows the results and the presence or absence of wrinkles on the film base material. In Table 1, "four-layer structure" means that the antireflection layer consists of four layers: ₅ Nb ₂ O layers, ₂ SiO layers, ₅ Nb ₂ O layers, and ₂ SiO layers. Furthermore, in Table 1, "-" means that no antireflection layer was formed.

As shown in Table 1, Reference Examples 13 to 15 in which no antireflection layer was formed showed higher moisture permeability values than Examples 1 to 5 and Reference Examples 1 to 12 in which an antireflection layer was formed. . Therefore, the moisture permeability of the entire antireflection film with a polarizer was considered to be equal to the moisture permeability of the antireflection layer.

Furthermore, as shown in Table 1, in Reference Examples 1 to 5 and 11 in which the antireflection layer is a single Nb ₂ O ₅ layer, the moisture permeability decreases as the oxygen gas flow rate (oxygen gas introduction ratio) increases. It was getting bigger. For example, the moisture permeability of Reference Example 5 in which the oxygen gas flow rate was 50 sccm was 4.5 times that of Reference Example 11 in which the oxygen gas flow rate was 0 sccm. On the other hand, in Reference Examples 6 to 10 and 12, in which _two single SiO layers were used as the antireflection layer, the change in moisture permeability was relatively small even when the oxygen gas flow rate (oxygen gas introduction ratio) was increased. . For example, the moisture permeability of Reference Example 10 in which the oxygen gas flow rate was 50 sccm was 1.1 times that of Reference Example 12 in which the oxygen gas flow rate was 0 sccm. From this result, it is considered that the effect of increasing the moisture permeability of the antireflection layer by the bombardment treatment using a combination of rare gas and oxygen gas is significantly manifested when the Nb ₂ O ₅ layer is employed.

In Examples 1 to 5, an antireflection layer containing a niobium oxide thin film was formed after bombardment using a rare gas (argon gas) and oxygen gas. Further, in Examples 1 to 5, the high temperature durability evaluation result was A, and there were no wrinkles in the film base material after the bombardment treatment process. Therefore, in Examples 1 to 5, it was possible to obtain an antireflection film (an antireflection film with a polarizer) having excellent high-temperature durability while suppressing deformation of the film base material during production.

<Production of anti-reflection film>
Next, methods for producing the antireflection films of Examples 6 to 15 and Comparative Examples 1 to 3 will be described.

[Example 6]
(Hard coat layer formation process)
100 parts by weight of ultraviolet curable urethane acrylate monomer (refractive index: 1.51), 14 parts by weight of polystyrene beads (refractive index: 1.59, number average primary particle diameter: 3.5 μm), and 5 parts by weight. The alkylphenone photopolymerization initiator, 135 parts by weight of toluene, and 10 parts by weight of ethyl acetate were mixed to prepare a composition for forming a hard coat layer having a solid content concentration of 45% by weight. Next, the hard coat layer forming composition was applied to one main surface of a TAC film (thickness: 40 μm, refractive index: 1.49) as a transparent film to form a coating film. Next, the coating film was dried by heating at a temperature of 80° C. for 2 minutes, and then cured by ultraviolet irradiation. As a result, an antiglare hard coat layer (hard coat layer having an uneven structure on the surface) having a thickness of 7 μm was formed on one main surface of the TAC film, and a transparent film with a hard coat layer (film base material) was obtained.

(Bombarding process)
Using a roll-to-roll type plasma processing apparatus, the transparent film with a hard coat layer is transported under the conditions of a pressure of 0.6 Pa and an effective power density of 0.34 W min/cm ² m. The main surface of the hard coat layer of the film (specifically, the main surface of the hard coat layer on the side opposite to the TAC film side) was subjected to bombardment treatment. During the bombardment process, argon gas (flow rate: 1049 sccm) and oxygen gas (flow rate: 1 sccm) were introduced into the apparatus. Hereinafter, the transparent film with a hard coat layer after bombardment treatment may be referred to as "optical film F2".

Next, the primer layer forming step and the antireflection layer forming step will be explained. In addition, in the primer layer forming step and the antireflection layer forming step, when forming (film forming) the oxide film, the film was formed while introducing argon gas and oxygen gas into the film forming chamber. In addition, when forming an oxide film, the pressure is kept constant by adjusting the amount of argon gas introduced and exhausted, and the film formation mode is controlled to be in the transition region by plasma emission monitoring (PEM) control. The amount of oxygen gas introduced was adjusted to maintain the following.

(Primer layer formation process)
The obtained optical film F2 was introduced into a roll-to-roll type sputtering film forming apparatus, and the pressure inside the film forming chamber was reduced to 1×10 ⁻⁴ Pa. Next, while conveying the optical film F2, the surface temperature of the film forming roll was set to -8°C, and a 3.5 nm thick SiOx layer (x <2) was formed (film formed). A Si target was used as a target material to form the primer layer. When forming a film by reactive sputtering, the power source was an MFAC power source (frequency: 40 kHz), the power density was 3 W/cm ² , and the pressure inside the film forming chamber was 0.4 Pa.

(Anti-reflection layer formation process)
Following the formation of the primer layer, while transporting the optical film F2 on which the primer layer has been formed using a roll-to-roll type sputtering film forming apparatus, a first film is deposited on one main surface of the primer layer by reactive sputtering. Layer: ₅ layers of Nb ₂ O with a thickness of 12 nm (refractive index: 2.33), 2nd layer: ₂ layers of SiO with a thickness of 28 nm (refractive index: 1.46), 3rd layer: ₅ layers of Nb ₂ O with a thickness of 100 nm , and fourth layer: 85 nm thick SiO ₂ layer were formed in this order. As a result, an antireflection layer having a four-layer structure (a four-layer structure consisting of the first layer, second layer, third layer, and fourth layer) was formed on one main surface of the primer layer, and the antireflection layer of Example 6 was formed. A protective film was obtained. In the deposition of each of the first to fourth layers, the surface temperature of the film-forming roll was -8° C., and the power source was an MFAC power source (frequency: 40 kHz). Furthermore, in the deposition of the first layer and the third layer, a Nb target was used, the power density was 13 W/cm ² , and the pressure inside the deposition chamber was 0.5 Pa. Further, in forming the second layer and the fourth layer, a Si target was used, the power density was 8 W/cm ² , and the pressure inside the film forming chamber was 0.5 Pa.

[Examples 7 to 15 and Comparative Examples 1 to 3]
Example 7 to Antireflection films of No. 15 and Comparative Examples 1 to 3 were obtained, respectively.

<Production of reference example of anti-reflection film>
Next, as films according to Reference Examples 6 to 15, methods for producing films of Reference Examples 16 and 17 will be described.

[Reference Examples 16 and 17]
The effective power density in the bombardment process, the flow rate of argon gas in the bombardment process, and the flow rate of oxygen gas in the bombardment process were as shown in Table 2 below, and the primer layer formation process and antireflection layer formation process. Films of Reference Examples 16 and 17 were obtained by the same manufacturing method as in Example 6, except that the above was not carried out.

<Evaluation method for Examples 6 to 15, Comparative Examples 1 to 3, Reference Example 16 and Reference Example 17>
Below, the evaluation method of the antireflection films of Examples 6 to 15 and Comparative Examples 1 to 3 and the films of Reference Examples 16 and 17 (hereinafter, each of these may be referred to as "evaluation target film S2") will be explained. do.

[Moisture permeability]
According to Annex B of JIS K7129:2008, the moisture permeability of the film S2 to be evaluated was measured in an atmosphere with a temperature of 40° C. and a relative humidity of 90%.

[Evaluation of high temperature durability]
The TAC film of the evaluation target film S2 is attached to one main surface of a separately prepared polarizer, and the separately prepared TAC film (thickness: 40 μm, refractive index: 1.49) is attached to the other main surface of the polarizer. By pasting them together, an antireflection film with a polarizer was produced. As the polarizer, a PVA-based polarizer was used, which was made by stretching a polyvinyl alcohol film having an average degree of polymerization of 2,700 and a thickness of 75 μm six times while dyeing with iodine. In addition, for bonding (adhesion) between the PVA polarizer and the TAC film, a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: After bonding with a roll bonding machine using an adhesive consisting of an aqueous solution containing 5 mol %) and methylolmelamine in a weight ratio of 3:1, they were heated and dried in an oven. Next, the obtained antireflection film with a polarizer was subjected to a heating test. Specifically, the antireflection film with a polarizer was placed in a hot air oven at a temperature of 95° C., and taken out after 1000 hours. Next, a commercially available polarizing plate was placed on the backlight, and the antireflection film with a polarizer after the heating test was placed on top of it in a crossed nicol state, and the appearance of the antireflection film with a polarizer was visually observed. The presence or absence of any changes was confirmed. Items with no change in appearance before and after the heating test are rated A (excellent in high-temperature durability), and items with a change in appearance before and after the heating test are rated B (not excellent in high-temperature durability). ).

[Presence or absence of wrinkles]
When producing the evaluation target film S2, the film base material after the bombardment process was visually observed to confirm the presence or absence of wrinkles on the film base material. If there were no wrinkles, it was evaluated as ``the deformation of the film base material during manufacturing was suppressed,'' and if there were wrinkles, it was evaluated as ``the deformation of the film base material during manufacturing was not suppressed.'' .

[Arithmetic mean roughness Ra]
The surfaces of the hard coat layers of the films of Reference Examples 16 and 17 were observed using an atomic force microscope (“Dimension Edge” manufactured by Bruker), and from the observed images of 1 μm square, the arithmetic of the surface of each hard coat layer was determined. The average roughness Ra was determined. The arithmetic mean roughness Ra of the hard coat layer surface of Reference Example 16 (oxygen gas flow rate: 0 sccm) was 0.51 nm. Further, the arithmetic mean roughness Ra of the hard coat layer surface of Reference Example 17 (oxygen gas flow rate: 50 sccm) was 0.55 nm. Therefore, as the flow rate of oxygen gas (oxygen gas introduction ratio) in the bombardment process increased, the arithmetic mean roughness Ra of the hard coat layer surface increased. From this result, by increasing the flow rate of oxygen gas (oxygen gas introduction ratio) in the bombardment process, the unevenness of the surface of the film base material becomes larger, and as a result, the columnar growth of the sputtered film formed on the film base material It is presumed that this promotes the formation of an antireflection layer with high moisture permeability.

<Evaluation results of Examples 6 to 15, Comparative Examples 1 to 3, Reference Example 16 and Reference Example 17>
Regarding Examples 6 to 15, Comparative Examples 1 to 3, Reference Example 16, and Reference Example 17, the effective power density in the bombardment process, the flow rate of argon gas and the flow rate of oxygen gas in the bombardment process, and the introduction of oxygen gas in the bombardment process Table 2 shows the evaluation results of ratio, presence or absence of an antireflection layer, moisture permeability, high temperature durability, and presence or absence of wrinkles on the film base material.

As shown in Table 2, Reference Examples 16 and 17 in which no antireflection layer was formed showed higher moisture permeability values than Examples 6 to 15 and Comparative Examples 1 to 3 in which antireflection layers were formed. . Therefore, the moisture permeability of the entire antireflection film was considered to be equal to the moisture permeability of the antireflection layer.

In Examples 6 to 15, an antireflection layer containing a niobium oxide thin film was formed after bombardment using a rare gas (argon gas) and oxygen gas. Further, in Examples 6 to 15, the high temperature durability evaluation result was A, and there were no wrinkles in the film base material after the bombardment process. Therefore, in Examples 6 to 15, it was possible to obtain antireflection films with excellent high-temperature durability while suppressing deformation of the film base material during production.

In Comparative Examples 1 to 3, only argon gas was used as the gas used in the bombardment process, without using oxygen gas. Furthermore, in Comparative Examples 1 and 2, the moisture permeability values were smaller than those in Examples 6 to 15, and as a result, the high temperature durability evaluation result was B. Therefore, in Comparative Examples 1 and 2, it was not possible to obtain an antireflection film with excellent high-temperature durability. Moreover, in Comparative Example 3, there were wrinkles in the film base material after the bombardment treatment process. Therefore, in Comparative Example 3, deformation of the film base material during manufacturing could not be suppressed.

As shown in Table 2, by increasing the effective power density in the bombardment process, the moisture permeability of the antireflection layer can be increased. However, if the effective power density is increased too much as in Comparative Example 3, the film base material becomes easily deformed. On the other hand, in Examples 6 to 15, by bombarding with a rare gas and oxygen gas, the moisture permeability of the antireflection layer could be increased even if the effective power density was reduced. From the above results, it was shown that according to the production method of the present invention, an antireflection film having excellent high-temperature durability can be produced while suppressing deformation of the film base material during production.

10: Anti-reflection film 11: Transparent film 12: Hard coat layer 13: Film base material 14: Primer layer 19: Anti-reflection layer

Claims (9)

A method for producing an antireflection film comprising a film base material and an antireflection layer provided on one main surface side of the film base material, the method comprising:
a step Sa of bombarding the one main surface of the film base material using a rare gas and oxygen gas;
step Sb of forming the antireflection layer on the main surface side subjected to the bombardment treatment,
The antireflection layer is made of a multilayer film including a niobium oxide thin film and an inorganic thin film having a different refractive index from the niobium oxide thin film ,
In the step Sa, the ratio of the amount of oxygen gas introduced to the sum of the amount of rare gas introduced and the amount of oxygen gas introduced is 0.0009 or more and 0.0500 or less,
A method for producing an antireflection film , wherein in the step Sa, bombardment is performed under conditions of a pressure of 0.1 Pa or more and 1.0 Pa or less . The method for producing an antireflection film according to claim 1, wherein the rare gas is argon gas. The method for manufacturing an antireflection film according to claim 1, wherein in the step Sb, the antireflection layer is formed by a sputtering method. The method for producing an antireflection film according to claim 1, wherein the antireflection layer has a thickness of 100 nm or more and 300 nm or less. The film base material includes a transparent film and a hard coat layer provided on one main surface side of the transparent film,
The method for manufacturing an antireflection film according to claim 1, wherein in the step Sa, a main surface of the hard coat layer opposite to the transparent film side is bombarded. The method for producing an antireflection film according to claim 5 , wherein the hard coat layer contains particles having a number average primary particle diameter of 0.5 μm or more and 5.0 μm or less . The method for producing an antireflection film according to claim 5 , wherein the transparent film is a triacetyl cellulose film. After the step Sa and before the step Sb, further comprising a step Sc of forming a primer layer on the bombarded main surface side,
The method for producing an antireflection film according to claim 1, wherein in the step Sb, the antireflection layer is formed on the main surface of the primer layer on the opposite side to the film base material side. In the step Sa, an effective power density of 0.01 W min/cm ² ・More than 0.60W・min/cm ² The method for producing an antireflection film according to claim 1, wherein the antireflection film is bombarded under conditions of - m or less.

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