JP2021092768A - Anti-reflection film - Google Patents

Abstract

To provide an anti-reflection film which exhibits a superior anti-reflection property, suppresses coloring, and offers superior reliability including interlayer adhesion, chemical resistance (alkali resistance in particular), etc.SOLUTION: An anti-reflection film provided herein comprises a transparent substrate, metal with cores, and anti-reflection layer. The anti-reflection layer consists of alternately laminated first refractive layers and second refractive layers having lower refractive index than the first refractive layers. The metal with cores is interspersed between the transparent substrate and the anti-reflection layer and contains titanium oxide.SELECTED DRAWING: Figure 1

Description

The present invention relates to an antireflection film. More specifically, the present invention relates to an antireflection film which exhibits excellent antireflection properties, suppresses coloring, and has excellent reliability such as interlayer adhesion and alkali resistance.

Conventionally, an antireflection film arranged on the surface of a display screen has been widely used in order to prevent reflection of external light on a display screen such as a CRT display, a liquid crystal display device, or a plasma display panel. The antireflection film is, for example, a multilayer film having a plurality of layers having different refractive indexes (Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-32524

The antireflection film described in Patent Document 1 combines a layer made of a high refractive index material and a layer made of a low refractive index material in order to achieve low reflectance. However, the antireflection film may be used for an in-vehicle display or in sunlight. In these cases, the antireflection film has very high required reliability. The antireflection film described in Patent Document 1 does not have sufficient chemical resistance (particularly alkali resistance) and may easily peel off.

The present invention has been made in view of such conventional inventions, exhibits excellent antireflection properties, suppresses coloring, and has interlayer adhesion, chemical resistance (particularly alkali resistance), and the like. An object of the present invention is to provide an antireflection film having excellent reliability.

As a result of diligent studies, the present inventor has provided an antireflection layer in which a first refracting layer and a second refracting layer having a refractive index lower than that of the first refracting layer are alternately laminated, and is a transparent group. The present invention has been completed by finding that the above problems can be solved by providing the cored metal in which the cored metal is interspersed between the material and the antireflection layer. That is, the antireflection film of the present invention that solves the above problems mainly includes the following configurations.

(1) A transparent base material, a cored metal, and an antireflection layer are provided, and the antireflection layer is a first refracting layer and a second refracting layer having a refractive index lower than that of the first refracting layer. The nucleated metal is interspersed between the transparent base material and the antireflection layer, and the nucleated metal is an antireflection film containing titanium oxide. ..

According to such a configuration, the antireflection film suppresses coloring and exhibits excellent antireflection property in a wide band. Further, in the antireflection film, the transparent base material and the antireflection layer are firmly adhered to each other by the cored metal, and the reliability such as chemical resistance (particularly alkali resistance) is excellent.

(2) The antireflection film according to (1), wherein the maximum value of the reflectance in the wavelength range of 450 nm to 700 nm is 2.0% or less.

With such a configuration, the antireflection film exhibits better antireflection properties.

(3) The antireflection film according to (1) or (2), wherein the transparent base material has a hard coat layer on at least one of them.

According to such a configuration, the antireflection film exhibits more excellent durability, chemical resistance and the like.

(4) The antireflection film according to any one of (1) to (3) _{, wherein the antireflection layer is a second refractive layer containing SiO 2} as the outermost surface layer of the antireflection layer.

According to such a configuration, the antireflection film exhibits more excellent durability, chemical resistance and the like.

According to the present invention, it is possible to provide an antireflection film which exhibits excellent antireflection properties, suppresses coloring, and has excellent reliability such as interlayer adhesion and chemical resistance (particularly alkali resistance). it can.

FIG. 1 is a schematic cross section showing an antireflection film according to an embodiment of the present invention. FIG. 2 is a spectral reflectance spectrum of the antireflection film of Examples 3 to 4 of the present invention. FIG. 3 is a spectral reflectance spectrum of the antireflection film of Example 5 of the present invention.

<Anti-reflective film>
FIG. 1 is a schematic cross section showing an antireflection film 1 according to an embodiment of the present invention. The antireflection film 1 of the present embodiment includes a transparent base material 2, a cored metal 3, and an antireflection layer 4. The antireflection layer 4 is a layer in which a first refracting layer 41 and a second refracting layer 42 having a refractive index lower than that of the first refracting layer 41 are alternately laminated. The cored metal 3 is a layer in which the cored metal is scattered. Nucleated metals include titanium oxide. Each will be described below.

(Transparent base material 2)
The transparent base material 2 is not particularly limited. As an example, the transparent base material 2 may be a transparent resin film, and is a cellulose-based resin (for example, triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, nitro cellulose). Polyamide resin (for example, nylon-6, nylon-66), polyimide resin, polycarbonate resin, polyester resin (for example, polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyethylene-1) , 2-Diphenoxyetane-4,4'-dicarboxylate, polybutylene terephthalate), polyolefin resin (for example, polyethylene, polypropylene, polymethylpentene), polysulfone resin, polyethersulfone resin, polyarylate resin , Polyetherimide resin, polymethylmethacrylate resin, polyetherketone resin, polystyrene resin, polyvinyl chloride resin, polyvinyl alcohol resin, ethylene vinyl alcohol resin, (meth) acrylic resin, (meth) acrylonitrile resin, etc. .. The transparent base material 2 may be a single layer or a laminated body of a plurality of resin films. Further, the transparent base material 2 may be provided with a hard coat layer described later. Furthermore, the transparent substrate 2 may contain any additive. Additives are, for example, antistatic agents, UV absorbers, plasticizers, lubricants, colorants, antioxidants, flame retardants and the like.

The thickness of the transparent base material 2 is not particularly limited. As an example, the thickness of the transparent base material 2 is preferably 12 to 300 μm. When the thickness of the transparent base material 2 is within the above range, the antireflection film 1 is excellent in transparency.

(Metal with core 3)
The cored metal 3 is provided to improve the adhesion between the transparent base material 2 and the antireflection layer 4. The cored metal 3 is scattered between the transparent base material 2 and the antireflection layer 4. Further, the cored metal 3 does not exist as a continuous film of metals, but is interspersed with metals.

The cored metal contains TiOx. The degree of oxidation x of TiOx is up to 0.1 to 2, and the preferred degree of oxidation is 1.5 to 2.0. The degree of oxidation can be measured by X-ray photoelectron spectroscopy (XPS) or secondary ion mass spectrometry (SIMS).

The method for forming the cored metal 3 is not particularly limited. As an example, the nucleated metal 3 is applied onto the transparent base material 2 by a method such as sputtering under vacuum or atmospheric pressure plasma under the atmosphere. The attached metal with a nucleus is scattered on the transparent base material 2 in an island shape. In the present embodiment, the metals scattered in this way are referred to as the cored metal 3.

The transparent base material on which the cored metal 3 is formed is then provided with an antireflection layer 4. At this time, the cored metal exists between the antireflection layer 4 provided on the periphery and the surface thereof and the transparent base material 2 as a core for improving the interlayer adhesion, and exerts its effect.

Titanium oxide, which is a metal with a nucleus, is transparent. Therefore, even if the metal with a nucleus 3 has some oxygen deficiency and absorption occurs, it is absorbed in the entire wavelength range, so that it is hard to be colored.

The amount of the cored metal adhered to the surface of the base material for forming the cored metal 3 (hereinafter, also simply referred to as the amount of adhesion) is not particularly limited. As an example, the cored metal is assumed to have the cored metal evenly dispersed over a unit area portion, and the thickness of the metal particles (core metal 3) (approximately average thickness in side view). ) Is preferably 0.01 nm or more, and more preferably 0.3 nm or more. The amount of the cored metal adhered is preferably such that the height of the cored metal 3 from the surface of the base material assumed above is 10 nm or less, and is preferably 5.0 nm or less. Is more preferable. When the amount of adhesion is within the above range, the nucleated metal 3 is appropriately interspersed with the nucleated metal, and the reliability such as interlayer adhesion between the transparent base material and the antireflection layer and alkali resistance is further improved. I can let you.

The thickness (height) of the cored metal 3 assumed above may be affected by the dimensions of the cored metal (titanium oxide) used. That is, there are cases where only one grain of nuclear metal is present on the surface of the base material in a substantially side view, and there are cases where multiple grains are present in a piled state. Can be set.

(Anti-reflective layer 4)
The antireflection layer 4 is a layer in which a first refracting layer 41 and a second refracting layer 42 having a refractive index lower than that of the first refracting layer 41 are alternately laminated. In the present embodiment, the refractive index can be measured by, for example, an ellipsometer.

-First refractive index layer 41
The material (high-refractive material) constituting the first refractive layer 41 is not particularly limited. As an example, high-refractive-index materials include titanium oxide (TiO ₂ , refractive index: 2.5), niobium oxide (NbOy (1 ≦ y ≦ 2.5)), selenium oxide (Ce ₂ O ₂ , refractive index: 2.4), tantalum oxide (Ta ₂ O ₅ , refractive index: 2.3), zirconium oxide (ZrO ₂ , refractive index: 2.1) and the like. Among these, the high-refractive-index material is preferably niobium oxide (NbOy (1 ≦ y ≦ 2.5)) from the viewpoint of sputtering rate and reliability, and niobium pentoxide (Nb ₂ O ₅ , refractive index: 2). .3) is more preferable.

The method for forming the first refractive layer 41 is not particularly limited. As an example, the first refracting layer 41 can be formed by setting a target of a highly refracting material (for example, NbOx) in a magnetron sputtering apparatus _{and performing sputtering in an Ar, O 2 atmosphere.}

The thickness of the first refracting layer 41 can be various depending on the substantially side view height of the cored metal, that is, the thickness may be freely set to some extent depending on the desired degree of antireflection performance. Absent.

-Second refractive index layer 42
The second refracting layer 42 has a lower refractive index than the first refracting layer 41. The material (low refraction material) constituting the second refraction layer 42 is not particularly limited. As an example, the low-refractive material is silicon oxide (SiOx (1 ≦ x ≦ 2), refractive index: 1.46), magnesium fluoride (MgF ₂ , refractive index: 1.38) and the like. Among these, the low-refractive-index material is preferably silicon oxide (SiOx (1 ≦ x ≦ 2)) and silicon dioxide (SiO ₂ , refractive index: 1.46) from the viewpoint of sputtering rate and reliability. Is more preferable.

The method for forming the second refractive layer 42 is not particularly limited. As an example, the second refraction layer 42 can be formed by setting a target of a low refraction material (for example, SiOx) in a magnetron sputtering apparatus _{and performing sputtering in an Ar, O 2 atmosphere.}

The thickness of the second refractive layer 42 is not particularly limited. The thickness of the second refracting layer 42 can be various depending on the substantially side view height of the cored metal, that is, the thickness may be freely set to some extent depending on the desired degree of antireflection performance. ..

In the antireflection film 1 of the present embodiment, the transparent base material 2 and the first refracting layer 41 are in close contact with each other by the cored metal 3, and the second refracting layer 42 is laminated on the transparent base material 2. .. The number of times the lamination of the first refracting layer 41 and the second refracting layer 42 is repeated may be once or more, and preferably twice or more. When the number of repetitions of laminating the first refracting layer 41 and the second refracting layer 42 in the antireflection layer 4 is within the above range, the obtained antireflection film 1 is suppressed from being colored and has a wide band. Shows excellent anti-reflection properties.

(Other layers)
The antireflection film 1 of the present embodiment may be provided with another layer in addition to the transparent base material 2, the cored metal 3 and the antireflection layer 4 described above. Other layers are, for example, a hard coat layer, an antifouling layer and the like.

-Hard coat layer The hard coat layer is preferably provided on at least one surface of the transparent base material. FIG. 1 illustrates a case where hard coat layers (hard coat layer 2a and hard coat layer 2b) are provided on both sides of the transparent base material. By providing the hard coat layer, the antireflection film 1 can exhibit more excellent durability, chemical resistance and the like.

The hard coat layer is not particularly limited. As an example, the hard coat layer is an acrylic or silicone hard coat layer. The hard coat layer can be formed by UV curing or thermosetting an appropriate coating liquid.

The thickness of the hard coat layer is not particularly limited. As an example, the thickness of the hard coat layer is preferably 0.1 to 20 μm from the viewpoint of imparting excellent durability, chemical resistance, etc. to the obtained antireflection film.

When the hard coat layer 2a is provided, the cored metal 3 is provided on the hard coat layer 2a provided on the transparent base material 2.

The hard coat layer may be formed directly on the transparent substrate 2 or may be formed via a primer layer (not shown).

When the hard coat layer is formed on the primer layer, the primer layer is not particularly limited. As an example, the primer layer is an acrylic-based, polyester-based, polyurethane-based, rubber-based or other primer layer. The thickness of the primer layer is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm.

・ Antifouling layer 5
The antifouling layer 5 is provided so as to cover the outermost surface of the antireflection film 1 so as to suppress the adhesion of stains such as fingerprints and to easily remove the adhered stains. In addition, since the surface becomes slippery, scratch resistance is provided. Specifically, the antifouling layer 5 is provided so as to cover the layer (second refracting layer 42) constituting the outermost surface layer among the antireflection layers 4 described above.

The second refracting layer 42 covered with the antifouling layer 5 is preferably a layer containing _{SiO 2. By covering the second refractive layer 42 containing SiO 2} with the antifouling layer 5, the obtained antireflection film 1 can be imparted with better durability, chemical resistance and the like.

The antifouling layer 5 is not particularly limited. As an example, the antifouling layer 5 is made of a fluororesin, a silicone resin, or the like.

The method for forming the antifouling layer 5 is not particularly limited. As an example, the antifouling layer 5 can be formed by applying a resin solution containing the above resin to the antireflection layer 4 by a known coating method.

The thickness of the antifouling layer 5 is not particularly limited. As an example, the thickness of the antifouling layer 5 is preferably 1 nm or more, and more preferably 5 nm or more. The thickness of the antifouling layer 5 is preferably 50 nm or less, more preferably 20 nm or less. When the thickness of the antifouling layer 5 is within the above range, the obtained antireflection film 1 can exhibit excellent optical characteristics, scratch resistance, antifouling property and the like.

Returning to the description of the entire antireflection film 1, the antireflection film 1 of the present embodiment includes the above-mentioned cored metal 3 and the antireflection layer 4. As a result, the antireflection film 1 is suppressed from being colored and exhibits excellent antireflection properties in a wide band. Specifically, the antireflection film 1 is adjusted so that the maximum value of the reflectance in the wavelength range of 450 nm to 700 nm is low. The maximum value of the reflectance is preferably 2.0% or less, and more preferably 1.0% or less. The antireflection film 1 of the present embodiment exhibits excellent antireflection properties in a wide color gamut because the maximum value of the reflectance is adjusted to be within the above range. The reflectance of the antireflection film 1 of the present embodiment has a wavelength of 380 to 780 nm using an ultraviolet visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation) when the antireflection layer 4 is used as the surface. It can be calculated by measuring the visual reflectance (calculation of visual reflectance from 5 degree reflectance measurement) in.

Further, the reflectance of the antireflection film 1 of the present embodiment has a wavelength of 380 to 780 nm using an ultraviolet visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation) when the antireflection layer 4 is used as a surface. It can be measured under the condition of 5 ° specular reflection in. At the time of measurement, a black vinyl tape is attached to the surface on the transparent substrate side to eliminate the influence of backside reflection.

As described above, the antireflection film of the present embodiment is suppressed in coloring and exhibits excellent antireflection property in a wide band. Further, in the antireflection film, the transparent base material and the antireflection layer are firmly adhered to each other by the cored metal, and the reliability such as chemical resistance (particularly alkali resistance) is excellent.

The antireflection film of the present embodiment can be suitably applied to a display screen such as a CRT display, a liquid crystal display device, or a plasma display panel. In particular, the antireflection film exhibits excellent antireflection properties even when used in an in-vehicle display or in sunlight.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "part" means "parts by mass".

<Example 1>
A transparent substrate (thickness 100 μm) made of PET was prepared. A hard coat layer (acrylic acid ester composition) having a thickness of 1.5 μm was formed on the transparent substrate by a wet coating method (two reverse method). Next, the Ti sputtering target was set in a magnetron sputtering apparatus, and sputtering was performed to form a cored metal (thickness 1.3 nm) made of TiOx on the hard coat layer. Next, the NbOx and Si targets are set in a magnetron sputtering apparatus, _{and sputtering is performed in an Ar and O 2} atmosphere to perform a first refracting layer (Nb ₂ O ₅ layer, thickness 15 nm) and a second refracting layer (SiO ₂ layer, thickness). 28 nm), the first refracting layer (Nb ₂ O ₅ layer, thickness 120 nm), and the second refracting layer (SiO ₂ layer, thickness 90 nm) were formed in this order. As a result, the transparent base material (resin film / hard coat layer) / metal with core (diox) / first refracting layer (Nb ₂ O ₅ layer) / second refracting layer (SiO ₂ layer) / first refracting layer (Nb) _An antireflection film having a layer structure composed of 2 O ₅ layers) / a second refraction layer (SiO _{2 layers) was produced.}

<Example 2, Comparative Examples 1 and 2>
An antireflection film was prepared by the same method as in Example 1 except that the raw materials and dimensions shown in Table 1 were changed. In Comparative Example 2, instead of the cored metal, an adhesion layer made of SiOx was provided.

The film thickness of TiOx used as the metal layer with a nucleus was measured by a wavelength dispersive fluorescent X-ray analyzer. Further, SiOx used as the cored metal layer, Nb ₂ O _{5 used as the first refraction layer, and SiO 2} used as the second refraction layer have the predetermined film thicknesses shown in Tables 1 and 2 by the following methods. (The same applies to Examples 3 to 5 and Comparative Examples 3 to 6 described later). First, each layer was formed into a single layer on a substrate such as PET, and the film thickness at that time was measured with a reflection spectroscopic film thickness meter (FE-3000, manufactured by Otsuka Electronics Co., Ltd.). From the measurement result of the obtained film thickness, the conditions at the time of film formation were adjusted by ratio calculation, and the film was formed so as to have a predetermined film thickness.

With respect to the antireflection films obtained in Examples 1 and 2 and Comparative Example 1, the total light transmittance (a *, b * and Y), the specular reflectance (a *, b * and Y), were determined according to the following methods. Adhesion (after initial adhesion and moisture resistance test) and chemical resistance (alkali resistance) were evaluated. The results are shown in Table 1.

(Total light transmittance (a *, b * and Y))
The total light transmittance is the visual transmittance (condition: total transmission) at a wavelength of 380 to 780 nm when the antireflection layer is used as the surface using an ultraviolet-visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation). It was calculated by measuring the visual reflectance from the rate measurement).

(Specular reflectance (a *, b * and Y))
The regular reflectance was measured using an ultraviolet-visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation) under the condition of 5 ° specular reflection at a wavelength of 380 to 780 nm when the antireflection layer was used as the surface. .. At the time of measurement, a black vinyl tape was attached to the surface on the transparent substrate side to eliminate the influence of backside reflection.

(Adhesion)
After film formation and after the moisture resistance test (temperature 85 ° C, humidity 85%, 1000 hours), 11 cuts to reach the transparent substrate are made at equal intervals (1.5 mm) in the antireflection film, 90 ° The orientation was changed and 11 cuts were made at equal intervals (1.5 mm), and the antireflection film was cut into 10 × 10 pieces vertically and horizontally. A cellophane adhesive tape was attached onto this and rubbed with an eraser to attach the tape to the coating film. After 1 to 2 minutes, the tape was held at a right angle to the coating film surface and the tape was momentarily peeled off to evaluate the state of the remaining antireflection layer.

(Alkali resistance)
A container containing a potassium hydroxide solution adjusted to 4% by mass was placed in a water bath, and the solution temperature was adjusted to 45 ° C. The antireflection film was immersed in the solution for 3 minutes, and the presence or absence of the coating film was confirmed.

As shown in Table 1, the antireflection films of Examples 1 and 2 showed excellent chemical resistance because only the outermost surface was peeled off in the alkali resistance test. Further, the antireflection films of Examples 1 and 2 have excellent adhesion even when left in a high temperature and high humidity for a long time. On the other hand, the antireflection film of Comparative Example 1 was inferior in alkali resistance and had a weak interlayer adhesion, and the antireflection layer was easily peeled off.

<Examples 3 to 5, Comparative Examples 3 to 6>
An antireflection film was produced by the same method as in Example 1 except that the raw materials and dimensions shown in Table 2 were changed. A transparent base material made of PET (polyethylene terephthalate) had a thickness of 188 μm, and a transparent base material made of TAC (triacetyl cellulose) had a thickness of 80 μm. In Examples 3 to 5, TiOx was used as the cored metal, and in Comparative Examples 5 to 6, SiOx was used as the cored metal. Comparative Examples 3 and 4 did not use a cored metal. Further, in the fifth embodiment, the antireflection layer is composed of two layers.

For the antireflection films obtained in Examples 3 to 5 and Comparative Examples 3 to 6, the total light transmittance (a *, b * and Y) and the specular reflectance (a *, b * and Y) are according to the following methods. ) And chemical resistance (alkali resistance) were evaluated. The results are shown in Table 2.

(Total light transmittance (a *, b * and Y))
As mentioned above.

(Specular reflectance (a *, b * and Y))
As mentioned above.

(Alkali resistance)
A container containing a potassium hydroxide solution adjusted to 2% by mass was placed in a water bath, and the solution temperature was adjusted to 45 ° C. The antireflection film was immersed in the solution for 2 minutes, washed with water to wipe off the water, and then the immersed portion was evaluated as follows.
-Surface layer SiO ₂ residual rate The residual rate of the second refracting layer on the surface layer was confirmed. The residual ratio was measured by performing spectrum fitting analysis with a reflection spectroscopic film thickness meter (FE-3000, manufactured by Otsuka Electronics Co., Ltd.).

As shown in Table 2, the antireflection films of Examples 3-4 showed excellent chemical resistance.

FIG. 2 is a spectral reflectance spectrum of the antireflection film of Examples 3 to 4. Further, FIG. 3 is a spectral reflectance spectrum of the antireflection film of Example 5. As shown in Table 2 and FIGS. 2 to 3, the antireflection film of the present invention has a maximum reflectance of 2.0% or less in the wavelength range of 450 nm to 700 nm, and has excellent antireflection properties. Shown.

1 Anti-reflection film 2 Transparent base material 2a, 2b Hard coat layer 3 Nucleated metal 4 Anti-reflection layer 41 First refraction layer 42 Second refraction layer 5 Antifouling layer

Claims (4)

It is provided with a transparent base material, a metal with a nucleus, and an antireflection layer.
The antireflection layer is a layer in which a first refracting layer and a second refracting layer having a refractive index lower than that of the first refracting layer are alternately laminated.
The cored metal is interspersed between the transparent base material and the antireflection layer.
The cored metal is an antireflection film containing titanium oxide. The antireflection film according to claim 1, wherein the maximum value of the reflectance in the wavelength range of 450 nm to 700 nm is 2.0% or less. The antireflection film according to claim 1 or 2, wherein the transparent base material has a hard coat layer on at least one of them. The antireflection film according to any one of claims 1 to 3 _{, wherein the antireflection layer is a second refractive layer containing SiO 2} as the outermost surface layer of the antireflection layer.

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