WO2016080314A1

WO2016080314A1 - Mold, production method for mold, antireflection film, and production method for antireflection film

Info

Publication number: WO2016080314A1
Application number: PCT/JP2015/082003
Authority: WO
Inventors: 美穂山田; 箕浦　潔; 隆裕中原
Original assignee: シャープ株式会社
Priority date: 2014-11-21
Filing date: 2015-11-13
Publication date: 2016-05-26
Also published as: CN107002272B; JP6322294B2; JPWO2016080314A1; CN107002272A

Abstract

A production method for a mold (100), the production method including: a step for preparing a cylindrical aluminum substrate (12) that has undergone mechanical mirror surface processing, the aluminum substrate (12) being formed from an Al-Mg-Si aluminum alloy; a step for performing a satin finish treatment on the surface of the aluminum substrate (12) by means of an alkaline etching liquid; a subsequent step for manufacturing a mold substrate (10) by forming an inorganic material layer (16) on the surface of the aluminum substrate (12) and by forming an aluminum film (18) on top of the inorganic material layer (16); and a step for alternately and repeatedly anodizing and etching the surface of the aluminum film (18) of the mold substrate (18) and forming an inverted moth-eye structure that has a plurality of micro-recesses (14p).

Description

Mold, mold manufacturing method, antireflection film, and antireflection film manufacturing method

The present invention relates to a mold, a method for manufacturing the mold, an antireflection film manufactured using the mold, and a method for manufacturing the antireflection film. The “mold” here includes molds used in various processing methods (stamping and casting), and is sometimes referred to as a stamper. It can also be used for printing (including nanoprinting).

2. Description of the Related Art An optical element such as a display device or a camera lens used for a television or a mobile phone is usually provided with an antireflection technique in order to reduce surface reflection and increase light transmission. For example, when light passes through the interface of a medium with a different refractive index, such as when light enters the interface between air and glass, the amount of transmitted light is reduced due to Fresnel reflection, and visibility is reduced. is there.

In recent years, attention has been focused on a method of forming a micro uneven pattern on the substrate surface, in which the period of the unevenness is controlled to be not more than the wavelength of visible light (λ = 380 nm to 780 nm) as an antireflection technique (see Patent Documents 1 to 3). reference). The two-dimensional size of the convex portions constituting the concavo-convex pattern expressing the antireflection function is 10 nm or more and less than 500 nm. Here, the “two-dimensional size” of the convex portion refers to the area equivalent circle diameter of the convex portion when viewed from the normal direction of the surface. For example, when the convex portion has a conical shape, The two-dimensional size corresponds to the diameter of the bottom surface of the cone. The same applies to the “two-dimensional size” of the recess.

This method utilizes the principle of a so-called moth-eye structure, and the refractive index for light incident on the substrate is determined from the refractive index of the incident medium along the depth direction of the irregularities. By continuously changing the refractive index, reflection in the wavelength region where reflection is desired to be prevented is suppressed.

The moth-eye structure has an advantage that it can exhibit an antireflection effect with a small incident angle dependency over a wide wavelength range, can be applied to many materials, and can form an uneven pattern directly on a substrate. As a result, a low-cost and high-performance antireflection film (or antireflection surface) can be provided.

The present applicant has developed a method using an anodized porous alumina layer obtained by anodizing aluminum as a method for producing an antireflection film (or antireflection surface) having a moth-eye structure (Patent Documents 2 and 3). ).

By using the anodized porous alumina film, a mold for forming a moth-eye structure on the surface (hereinafter referred to as “moth-eye mold”) can be easily manufactured. In particular, as described in Patent Documents 2 and 3, if the surface of the anodized aluminum film is used as a mold as it is, the effect of reducing the manufacturing cost is great. The surface structure of the moth-eye mold that can form the moth-eye structure is referred to as an “inverted moth-eye structure”.

Further, as described in Patent Documents 1 to 4, in addition to the moth-eye structure (microstructure), an uneven structure (macrostructure) larger than the moth-eye structure is provided, so that the antireflection film (antireflection surface) is provided. An anti-glare (anti-glare) function can be imparted. The two-dimensional size of the convex part or the concave part constituting the concavo-convex structure exhibiting the anti-glare function (sometimes referred to as “anti-glare structure”) is 200 nm or more and less than 100 μm. The surface structure of the mold that can form an antiglare structure is referred to as an “inverted antiglare structure”. The entire disclosure of Patent Documents 1 to 4 is incorporated herein by reference.

In this specification, the unevenness constituting the moth-eye structure (or inverted moth-eye structure) is referred to as micro unevenness, and the unevenness constituting the antiglare structure (or inverted antiglare structure) is referred to as macro unevenness. To. The range of the two-dimensional size of the macro unevenness partially overlaps the range of the two-dimensional size of the micro unevenness, but in the antireflection film (antireflection surface) having the antiglare function, the antiglare The concavo-convex structure constituting the structure is larger than the concavo-convex structure constituting the moth-eye structure that exhibits the antireflection function.

JP-T-2001-517319 Special Table 2003-531962 International Publication No. 2011/055757 International Publication No. 2013/146656

However, it is difficult to say that a method for efficiently producing a mold for forming an antireflection film (or an antireflection surface) having an appropriate antiglare function has been established.

For example, in the sandblasting method described in Patent Document 1, it is difficult to form a desired macro uneven structure imparting an antiglare function with good reproducibility. Further, in the cathode electrolysis method described in Patent Document 3, there may be a case where a macro uneven structure capable of sufficiently exhibiting the antiglare function cannot be formed.

Furthermore, the surface reflecting the continuous macro uneven structure without the flat portion of the resin layer formed by electrodeposition described in Patent Document 4 has a problem that the image is blurred. In recent years, with the progress of high definition display devices, there is a demand for an antireflection film having an appropriate antiglare function in which blurring of an image is suppressed.

The present invention provides an antireflection film (or antireflection surface) having an appropriate antiglare function and an appropriate specular reflectivity, a method for producing such an antireflection film, and such reflection. It is an object of the present invention to provide a mold for forming a prevention film and to provide a method capable of efficiently manufacturing such a mold.

A mold manufacturing method according to an embodiment of the present invention includes: (a) a cylindrical aluminum substrate formed of an Al—Mg—Si-based aluminum alloy, which has been subjected to mechanical mirror finishing (B) a step of treating the surface of the aluminum substrate with an aqueous solution containing a salt of hydrogen fluoride and ammonium, and (c) after the step (b), the aluminum substrate. Forming a mold base by forming an inorganic material layer on the surface and forming an aluminum film on the inorganic material layer, and (d) after the step (c), the aluminum film And (e) after the step (d), the porous alumina layer is brought into contact with an etching solution by anodizing the surface of the porous alumina layer. A step of enlarging the plurality of micro-recesses of the porous alumina layer, and (f) a step of growing the plurality of micro-recesses by further anodizing after the step (e). Is included.

In one embodiment, the aluminum substrate is an aluminum substrate that has been cold drawn. The aluminum substrate is an aluminum substrate formed by a hot extrusion method. The hot extrusion method may be a mandrel method or a boathole method. Cold drawing can be omitted. When the cold drawing process is not performed, it is preferable to use an aluminum substrate formed by a mandrel method.

In one embodiment, the method for manufacturing the mold further includes a degreasing step and a water washing step before the step (b).

In one embodiment, the step (b) is performed after 15 minutes after the rinsing step.

In one embodiment, the mold manufacturing method further includes a substrate surface etching step of etching the surface of the aluminum substrate using an alkaline etching solution before the step (b).

In one embodiment, the substrate surface etching step also serves as the degreasing step.

In one embodiment, the alkaline etching solution contains 0.03 mass% or more of an inorganic base or an organic base.

In one embodiment, the pH of the alkaline etching solution is 10 or more and 12 or less.

In one embodiment, the alkaline etching solution contains potassium hydroxide.

In one embodiment, the alkaline etching solution contains an organic compound having an amino group.

In an embodiment, the arithmetic average roughness Ra of the surface of the aluminum base material is 50 nm or more and 300 nm or less by the base material surface etching step and the step (b).

In one embodiment, at least 1.4 μm is removed from the surface of the aluminum substrate in the substrate surface etching step.

In one embodiment, before the step (b), an anodizing step for pretreatment and an etching step are further included.

In one embodiment, the anodizing step for the pretreatment uses an aqueous sulfuric acid solution as an electrolytic solution.

In one embodiment, the etching step for the pretreatment uses a phosphoric acid aqueous solution as an etchant.

In one embodiment, the salt of hydrogen fluoride and ammonium in the step (b) is ammonium hydrogen fluoride. In an embodiment, the aqueous solution containing a salt of hydrogen fluoride and ammonium contains 4 mass% or more of ammonium hydrogen fluoride. The step (b) is performed at about 10 ° C., for example. At this time, the satin treatment time is preferably in the range of 2 minutes 30 seconds to 8 minutes.

The mold according to the embodiment of the present invention is a mold manufactured by any one of the mold manufacturing methods described above.

The mold according to another embodiment of the present invention includes a plurality of convex portions having a two-dimensional size of 200 nm to 30 μm when viewed from the normal direction of the surface, and 2 when viewed from the normal direction of the surface. A porous alumina layer having a surface structure having a plurality of micro concave portions having a dimensional size of 10 nm or more and less than 500 nm.

An antireflection film manufacturing method according to an embodiment of the present invention includes a step of preparing any of the above molds, a step of preparing a workpiece, and photocuring between the mold and the surface of the workpiece. A step of curing the photocured resin by irradiating the photocured resin with light in a state where a resin is applied; and a step of peeling the anti-reflective film formed of the photocured resin cured of the mold; Is included.

The antireflection film according to the embodiment of the present invention is an antireflection film manufactured by the above-described method for manufacturing an antireflection film.

An antireflection film according to another embodiment of the present invention has a plurality of recesses having a two-dimensional size of 200 nm or more and 30 μm or less when viewed from the surface normal direction and a surface when viewed from the surface normal direction. It has a surface structure that has a plurality of micro-projections with a two-dimensional size of 10 nm or more and less than 500 nm, an incident angle of 5 °, a light receiving angle on the horizontal axis, and a maximum value of diffuse reflected light intensity of 80%. The point where the slope of the light distribution curve with the common logarithm of the relative diffuse reflectance (%) as the vertical axis changes discontinuously is within the range where the light receiving angle is over 0 ° and below 10 °. The relative diffuse reflectance (%) is in the range of 1% to 10%.

In one embodiment, the antireflection film has a haze value of about 7 or more and about 24 or less.

According to another embodiment of the present invention, there is provided a mold manufacturing method comprising: (a) a cylindrical aluminum substrate formed of an Al—Mg—Si-based aluminum alloy, and mechanically mirror-finished aluminum A step of preparing a base material, (b) a step of treating the surface of the aluminum base material with an alkaline etchant, and (c) after the step (b), the surface of the aluminum base material is inorganic. Forming a material layer and forming an aluminum film on the inorganic material layer, thereby producing a mold base; and (d) after the step (c), anodizing the surface of the aluminum film A step of forming a porous alumina layer having a plurality of micro-recesses, and (e) contacting the porous alumina layer with an etching solution after the step (d). Then, the step of expanding the plurality of micro concave portions of the porous alumina layer, and the step of (f) growing the plurality of micro concave portions by further anodizing after the step (e). Include.

In one embodiment, the arithmetic average roughness Ra of the surface of the aluminum base is 50 nm or more and 200 nm or less by the step (b).

In one embodiment, the alkaline etching solution contains 0.03 mass% or more of an inorganic base or an organic base. For example, the alkaline etching solution contains 0.96 mass% or more of an organic base.

In one embodiment, the pH of the alkaline etching solution is 9.5 or more and 11 or less.

In one embodiment, the alkaline etching solution contains potassium hydroxide.

In one embodiment, in the step (b), at least 1.4 μm is removed from the surface of the aluminum substrate.

In one embodiment, the step (b) is performed by bringing the surface of the aluminum base material into contact with the alkaline etching solution for 45 minutes or more.

In one embodiment, the step (b) also serves as a degreasing step.

In one embodiment, the aluminum substrate is an aluminum substrate formed by a mandrel method.

A mold according to still another embodiment of the present invention is a mold manufactured by any of the above-described mold manufacturing methods.

A mold according to still another embodiment of the present invention is seen from a plurality of macroscopic protrusions having a two-dimensional size of 200 nm to 30 μm when viewed from the normal direction of the surface and the normal direction of the surface. This is a mold having a porous alumina layer having a surface structure having a plurality of micro-recesses having a two-dimensional size of 10 nm or more and less than 500 nm.

An antireflection film manufacturing method according to another embodiment of the present invention includes a step of preparing any of the above molds, a step of preparing a workpiece, and the mold and the surface of the workpiece. In a state where the photocurable resin is applied, the photocurable resin is cured by irradiating the photocurable resin with light, and the mold is peeled off from the antireflection film formed of the cured photocurable resin. Process.

An antireflection film according to still another embodiment of the present invention is an antireflection film manufactured by the above-described method for manufacturing an antireflection film.

According to the embodiments of the present invention, there are provided a mold for forming an antireflection film (or an antireflection surface) having an appropriate antiglare function and an appropriate specular reflectivity, and a method capable of efficiently manufacturing such a mold. The The mold according to the embodiment of the present invention can form an antireflection film (antireflection surface) having an appropriate antiglare function, an appropriate specular reflectivity, and an excellent antireflection function. The antireflection film according to the embodiment of the present invention has a surface structure that exhibits an appropriate antiglare function, an appropriate specular reflectivity, and an excellent antireflection function.

(A)-(d) is typical sectional drawing for demonstrating the manufacturing method of the mold 100 for moth eyes of Embodiment 1 by this invention, (a) is the aluminum base material 12 of the mold 100 for moth eyes. (B) is a cross-sectional view schematically showing the surface structure of the aluminum substrate 12 having an inverted antiglare structure, and (c) is a diagram showing the surface of the aluminum substrate 12. It is typical sectional drawing of the type | mold base material 10 in which the inorganic material layer 16 and the aluminum film 18 were formed, (d) is the inverted anti-glare structure and the inverted moth-eye structure superimposed on the inverted anti-glare structure. It is typical sectional drawing of the mold 100 for moth eyes which has these. It is a flowchart explaining the manufacturing method of the mold 100 for moth eyes of Embodiment 1 by this invention. (A) is a laser microscope image (full scale 15 μm in the microscopic image) of the surface of the aluminum substrate 12 having an inverted antiglare structure formed by the satin treatment, and (b) is formed by the satin treatment. FIG. 6 is an SEM image (full scale 10 μm in the SEM image) when the surface of the aluminum substrate 12 having an inverted antiglare structure is observed from the vertical direction, and (c) is a schematic diagram of the inverted antiglare structure. It is a top view, (d) is a typical perspective view of the inverted anti-glare structure. (A) is an SEM image (full scale 10 μm in the SEM image) when the surface of the aluminum film 18 of the mold base 10 is observed from the vertical direction, and (b) is an inversion of the moth-eye mold 100. It is a SEM image (full scale 10 micrometers in a SEM image) when the surface of the porous alumina layer 14 which has a moth-eye structure is observed from a perpendicular direction. (A) And (b) is typical sectional drawing for demonstrating the manufacturing method of the moth-eye mold | type 100 of Embodiment 2 by this invention, (a) is the aluminum group which has the inverted anti-glare structure It is sectional drawing which shows the surface structure of the material 12 typically, (b) is typical sectional drawing of the type | mold base material 10 which formed the inorganic material layer 16 and the aluminum film 18 in the surface of the aluminum base material 12 (C) is a laser microscope image of the surface of the aluminum substrate 12 having an inverted antiglare structure formed by a satin treatment with an alkaline etching solution. It is a figure for demonstrating the manufacturing method of the anti-reflective film using the type | mold 100 for moth eyes. (A) and (b) are SEM images of an antireflection film having an antiglare function according to an embodiment of the present invention, and (a) is an SEM image (SEM image) when the surface of the antireflection film is observed from the vertical direction. (B) is an SEM image (full scale 3 μm in the SEM image) when the cross section and surface of the antireflection film are observed from an oblique direction. (A) ~ (c) is a schematic diagram of an antireflection film having an antiglare function according to an embodiment of the present invention, (a) is a schematic diagram when the surface of the antireflection film is observed from the vertical direction, (B) is a schematic diagram when the surface of an antireflection film is observed from an oblique direction, and (c) is a schematic diagram of a cross section of the antireflection film. (A) is a graph which shows the measurement result of the light distribution distribution of the diffuse reflection light by the antireflection film which has an anti-glare function, (b) is a schematic diagram which shows the measurement system of the light distribution distribution of a diffuse reflection light. (A) to (c) are SEM images (5000 times, full scale 10 μm in SEM image) of the surface of an aluminum base material that has been satin-treated with an aqueous solution containing ammonium hydrogen fluoride. It is a figure which shows the light distribution of the diffusely reflected light of the sample film produced using the aluminum base material (mold base material which carried out cold drawing processing) from which the time of a satin processing (process temperature of 35 degreeC) differs. It is a figure which shows the model calculation result which evaluated the anti-glare function and specular reflectivity. It is a figure which shows the light distribution of the diffuse reflected light of the sample film produced using the aluminum base material (mold base material which carried out cold drawing processing) from which the time of a satin processing (treatment temperature of 10 degreeC) differs. (A) And (b) is a figure which shows the SEM image of the surface of the aluminum base material (mold base material which is not cold-drawn) which performed the anodic oxidation and etching as pre-processing of a satin processing, ( a) shows the case where an aqueous oxalic acid solution is used as the electrolytic solution, and (b) shows the case where an aqueous sulfuric acid solution is used as the electrolytic solution. (A) to (d) are SEM images of the surface of a sample with different etching times using an aqueous phosphoric acid solution after anodizing with an aqueous sulfuric acid solution as a pretreatment for the satin treatment. Light distribution of diffusely reflected light from a film made using an aluminum base material that has been anodized (sulfuric acid aqueous solution) and etching as a pretreatment for matte treatment and then treated with different treatment times as a mold It is a figure which shows distribution. (A) is a SEM image of the surface after performing a satin treatment for 37 seconds to the aluminum base material of the mold base material produced using the aluminum base material subjected to cold drawing, (b) After performing anodic oxidation (sulfuric acid aqueous solution) and etching as pretreatment on the aluminum substrate of the mold substrate produced using an aluminum substrate that has not been subjected to cold drawing, a satin treatment is performed for 120 seconds. It is a SEM image of the surface after performing. (A) And (b) is a figure which shows typically the relationship of the magnitude | size of the macro uneven | corrugated structure for forming the conventional anti-glare structure, and the dot pitch Px of a row direction. (A) It is sectional drawing which shows typically the structure of a macro unevenness | corrugation for forming the conventional anti-glare structure, (b) is a typical cross section which shows the inverted moth eye structure superimposed on the macro unevenness | corrugation (C) is a schematic cross-sectional view enlarging an inverted moth-eye structure.

Hereinafter, a mold and a method for manufacturing the mold according to an embodiment of the present invention will be described with reference to the drawings.

First, referring to FIG. 16, the relationship between the macro uneven structure constituting the conventional anti-glare structure and the dot pitch Px in the row direction will be described. 16 (a) and 16 (b) are diagrams schematically showing the relationship between the macro uneven structure constituting the conventional anti-glare structure and the dot pitch Px in the row direction. Indicates a case where the macro uneven structure is larger than the dot pitch Px, and FIG. 16B shows a case where the macro uneven structure is smaller than the dot pitch Px. Here, the dots refer to R, G, and B dots that constitute pixels in a typical color liquid crystal display panel. That is, when the pixel in the color liquid crystal display panel is composed of three dots (R dot, G dot, and B dot) arranged in the row direction, the pixel pitch in the row direction is the dot pitch Px in the row direction. Tripled. Note that the pixel pitch in the column direction is equal to the dot pitch Py in the column direction.

As schematically shown in FIGS. 16A and 16B, the surface 28s having a macro uneven structure constituting the conventional anti-glare structure has a continuous corrugated surface shape having no flat portion. The macro uneven structure having such a continuous corrugated surface shape is characterized by the average value of the distance between adjacent macro concave portions (average inter-adjacent distance AD _int ) or the two-dimensional size AD _p of the concave portions. . Here, attention is focused on macro concave portions, but the same can be characterized by focusing on convex portions.

As shown in FIG. 16A, an average distance AD _int between the recesses (considered to be equal to the two-dimensional size AD _{p of the} recesses) is, for example, a dot pitch Px in the row direction (pixels having three dots ( In the case of R, G, B), if the pixel pitch in the row direction is larger than 3 times the dot pitch), a sufficient anti-glare function cannot be obtained. In order to fully exhibit the anti-glare function, as shown in FIG. 16B, the average adjacent distance AD _int (two-dimensional size AD _{p of the} recess) is substantially equal to each other and the dot pitch Is preferably smaller. The two-dimensional size of the recess means a two-dimensional expansion when viewed from the normal direction of the surface, and the recess is typically conical and when viewed from the normal direction of the surface. The shape of is substantially circular. At this time, the two-dimensional size corresponds to the diameter of the circle. If the convex portions are formed with a sufficiently high density, the average distance AD _int between two adjacent concave portions is substantially equal to the two-dimensional size AD _p of the concave portions. The pixel pitch is 254 μm for a display with a relatively low resolution, for example, a 100 ppi display. In the case of the antireflection film used in this display, the average distance AD _int between adjacent surfaces is preferably about 85 μm (254/3) or less.

For example, Patent Document 4 discloses a method for manufacturing an antireflection film in which a moth-eye structure is superimposed on an antiglare structure having a continuous corrugated surface 28s without a flat portion. With reference to FIG. 17, the manufacturing method of the moth-eye type | mold for forming the anti-reflective film which has the anti-glare function described in patent document 4 is demonstrated.

FIG. 17A is a cross-sectional view schematically showing an inverted antiglare structure for forming an antiglare structure, and FIG. 17B shows an inverted moth-eye structure superimposed on the inverted antiglare structure. FIG. 17C is a schematic cross-sectional view in which the inverted moth-eye structure is enlarged.

The surface 18cs having an inverted antiglare structure for forming the antiglare structure having the continuous corrugated surface 28s having no flat portion shown in FIG. 17A is an outer peripheral surface of a cylindrical metal substrate. It is obtained by forming an insulating layer with an electrodeposition resin containing a matting agent and forming an aluminum film 18c on the insulating layer. That is, the surface of the insulating layer formed of an electrodeposition resin containing a matting agent has a continuous corrugated surface shape without a flat portion, and the surface 18cs of the aluminum film 18c formed on the insulating layer is: Reflecting the shape of the surface of the insulating layer, it has a continuous corrugated surface shape without a flat portion. Since the shape of the surface 18cs of the aluminum film 18c constitutes an inverted antiglare structure, the macro unevenness of the surface 18cs of the aluminum film 18c is opposite to the macro unevenness of the surface 28s constituting the antiglare structure. is there.

Next, as shown in FIG. 17 (b), anodization and etching are alternately repeated on the surface of the aluminum film 18c having an inverted antiglare structure, so that an anodized porous film having micro concave portions 14p is obtained. An alumina layer 14c is formed. In this way, the moth-eye mold 200 having a surface in which the inverted moth-eye structure is superimposed on the inverted anti-glare structure is obtained.

As schematically shown in FIG. 17C, the porous alumina layer 14c is densely filled with micro concave portions 14p. The micro concave portion 14p is generally conical and may have stepped side surfaces. The two-dimensional size (opening diameter: D _p ) of the micro concave portion 14p is preferably 10 nm or more and less than 500 nm, and the depth (D _depth ) is preferably about 10 nm or more and less than 1000 nm (1 μm). Moreover, it is preferable that the bottom part of the micro recessed part 14p is pointed (the bottom part is a point). Furthermore, it is preferable that the micro concave portions 14p are closely packed, and assuming that the shape of the micro concave portions 14p when viewed from the normal direction of the porous alumina layer 14c is a circle, adjacent circles overlap each other, It is preferable that a flange is formed between the adjacent micro concave portions 14p. When the substantially conical micro concave portions 14p are adjacent so as to form a collar portion, the two-dimensional size D _p of the micro concave portions 14p is assumed to be equal to the average inter-adjacent distance D _int . Therefore, the moth-eye type porous alumina layer 14c for producing the antireflection film has a dense micro concave portion 14p with D _p = D _int of 10 nm or more and less than 500 nm and D _depth of 10 nm or more and less than 1000 nm (1 μm). It is preferable to have an irregularly arranged structure. The arrangement of the micro concave portions does not need to be completely random, and may be irregular so that light interference and diffraction do not substantially occur. Since the shape of the opening of the micro concave portion 14p is not strictly a circle, D _p is preferably obtained from the SEM image of the surface. The thickness t _p of the porous alumina layer 14c is about 1 μm or less. The above description of the inverted moth-eye structure of the porous alumina layer 14c is also valid for the moth-eye mold according to the embodiment of the present invention.

The antireflection film formed by using the mold manufactured by the mold manufacturing method described in Patent Document 4 has a problem that the image is blurred (described later with reference to FIG. 10B). This is because the inverted antiglare structure of the mold manufactured by the method described in Patent Document 4 has relatively large AD _int and AD _p . Therefore, in the manufacturing method described in Patent Document 4, it is difficult to form an antiglare structure that is suitably used for a high-definition display exceeding 300 ppi, for example.

According to embodiments of the present invention described below, an antiglare structure having an appropriate antiglare function (for example, a haze value of about 7 or more and about 24 or less) and an appropriate specular reflectivity, and an excellent antireflection effect are exhibited. An antireflective film (or antireflective surface) having a moth-eye structure is provided. In addition, according to the embodiment of the present invention, a mold for forming such an antireflection film is provided, and further, a method for efficiently manufacturing such a mold is provided. In addition, the mold manufactured by the mold manufacturing method according to the embodiment of the present invention is not limited to the illustrated example, and an antireflection film having a diffuse reflection performance with a small haze value (for example, about 1 to about 5) is formed. Can also be used.

(Embodiment 1)
First, with reference to FIGS. 1 to 4A, a method of manufacturing a mold according to Embodiment 1 of the present invention and a structure of a mold manufactured by such a manufacturing method will be described.

1 (a) to 1 (d) are schematic cross-sectional views for explaining a method of manufacturing the moth-eye mold 100 according to the first embodiment of the present invention, and FIG. 2 is a moth-eye according to the first embodiment of the present invention. 4 is a flowchart for explaining a method for manufacturing the mold 100.

The manufacturing method of the moth-eye mold 100 according to the first embodiment of the present invention includes the following steps (A) to (F) as shown in FIG.

(A) A step of preparing a cylindrical aluminum base material formed of an Al—Mg—Si based aluminum alloy and subjected to mechanical mirror finishing (B) Surface of the aluminum base material (C) After step (B), an inorganic material layer is formed on the surface of the aluminum substrate, and an aluminum film is formed on the inorganic material layer. A step of forming a mold substrate by forming (D) A step of forming a porous alumina layer having a plurality of microscopic recesses by anodizing the surface of the aluminum film after step (C) (E ) After step (D), the porous alumina layer is brought into contact with the etching solution to enlarge a plurality of micro concave portions of the porous alumina layer. (F) Step ( After), by further anodization, growing a plurality of microscopic recesses

In this specification, the mold base means an object to be anodized and etched in the mold manufacturing process. The aluminum substrate means bulk aluminum that can be self-supported.

Next, refer to FIGS. 1 (a) to (d). FIG. 1A is a schematic cross-sectional view of the aluminum base 12 of the moth-eye mold 100, and FIG. 1B schematically shows the surface structure of the aluminum base 12 having an inverted antiglare structure. FIG. 1C is a schematic cross-sectional view of the mold base 10 in which the inorganic material layer 16 and the aluminum film 18 are formed on the surface of the aluminum base 12, and FIG. FIG. 3 is a schematic cross-sectional view of a moth-eye mold 100 having an inverted antiglare structure and an inverted motheye structure superimposed on the inverted antiglare structure.

FIG. 1 shows a part of the moth-eye mold 100 in an enlarged manner, but the moth-eye mold 100 according to the first embodiment of the present invention has a cylindrical shape (roll shape). As disclosed in International Publication No. 2011/105206 by the present applicant, when a cylindrical moth-eye mold is used, an antireflection film can be efficiently produced by a roll-to-roll method. For reference purposes, the entire disclosure of WO 2011/105206 is incorporated herein by reference.

First, as shown in FIG. 1 (a), a cylindrical aluminum substrate 12 formed of an Al—Mg—Si based aluminum alloy, which has been subjected to mechanical mirror finishing, prepare.

Byte cutting is preferred as the mechanical mirror finish. If, for example, abrasive grains remain on the surface of the aluminum base 12, electrical conduction between the aluminum film 18 and the aluminum base 12 is facilitated in a portion where the abrasive grains exist. In addition to the abrasive grains, where there are irregularities, local conduction between the aluminum film 18 and the aluminum substrate 12 is likely to occur. When local conduction is made between the aluminum film 18 and the aluminum base 12, there is a possibility that a battery reaction occurs locally between the impurities in the aluminum base 12 and the aluminum film 18.

As will be described later with reference to experimental examples, the effect of the subsequent chemical matte treatment differs depending on the material of the aluminum substrate 12, and in order to obtain the above macro uneven structure, an Al—Mg—Si based aluminum An aluminum substrate 12 made of an alloy (for example, JIS A6063) is used.

The cylindrical aluminum substrate 12 is typically formed by a hot extrusion method. The hot extrusion method includes a mandrel method and a boathole method, and it is preferable to use an aluminum substrate 12 formed by the mandrel method. A seam (weld line) is formed on the outer peripheral surface of the cylindrical aluminum base material 12 formed by the boat hole method, and the seam is reflected in the moth-eye mold 100. Therefore, depending on the accuracy required for the moth-eye mold 100, it is preferable to use the aluminum substrate 12 formed by the mandrel method.

In addition, the problem of a seam can be eliminated by performing cold drawing processing with respect to the aluminum base material 12 formed by the boat hall method. Of course, cold drawing may be applied to the aluminum substrate 12 formed by the mandrel method.

Next, the surface of the aluminum base 12 is treated with an aqueous solution containing a salt of hydrogen fluoride and ammonium, so that the surface is inverted to the surface 12s of the aluminum base 12 as shown in FIG. An anti-glare structure is formed. The inverted anti-glare structure formed by the satin treatment has a plurality of macro convex portions 12p and a plurality of macro concave portions 12g. The macro convex portion 12p is substantially surrounded by the macro concave portion 12g, and the macro concave portion 12g exists as a groove that defines the outer periphery of the macro convex portion 12p.

An aqueous solution containing a salt of hydrogen fluoride and ammonium causes pitting corrosion. Examples of the salt of hydrogen fluoride and ammonium include ammonium fluoride (normal salt or neutral salt) and ammonium hydrogen fluoride (hydrogen salt or acidic salt). An aqueous solution containing a salt of hydrogen fluoride and ammonium has an advantage that it has less adverse effects on the human body and the environment than an aqueous solution of hydrogen fluoride. When ammonium hydrogen fluoride is used as the salt of hydrogen fluoride and ammonium, the concentration of ammonium hydrogen fluoride is, for example, 4 mass% or more. In addition to ammonium hydrogen fluoride, ammonium dihydrogen phosphate and / or ammonium sulfate may be added. Here, including the following experimental examples, an etching solution for treating aluminum with a satin finish was used in which a small amount of ammonium dihydrogen phosphate and ammonium sulfate was added to ammonium hydrogen fluoride. This etching solution is referred to as an aqueous solution containing ammonium hydrogen fluoride for the sake of simplicity. Such an etchant can be prepared using a chemi-cleaner manufactured by Nippon CB Chemical Co., Ltd. The time for the satin treatment with the aqueous solution containing ammonium hydrogen fluoride is, for example, 15 seconds or more and 180 seconds or less when the treatment temperature is 35 ° C. Since an aqueous solution containing ammonium fluoride has a weaker etching ability of aluminum than an aqueous solution containing ammonium hydrogen fluoride, an aqueous solution containing ammonium hydrogen fluoride is used by appropriately adjusting the concentration, processing temperature, and time. The same effect can be obtained.

In addition, a degreasing process and a water washing process are performed as needed before the satin treatment with an aqueous solution containing a salt of hydrogen fluoride and ammonium. Moreover, it is preferable to perform a satin treatment before 15 minutes pass after a washing process. Moreover, it is preferable to wash with water as needed between the steps using different treatment liquids.

In addition, when the matte finish was applied to the aluminum base material 12 that had been mirror-finished by bite cutting without performing cold drawing, cutting traces might be formed on the surface of the aluminum base material 12. The cut marks formed on the surface of the aluminum substrate 12 were also reflected in the aluminum film 18 formed on the aluminum substrate 12. In the present specification, not only the surface of the aluminum base 12 but also the trace caused by the cutting formed on the aluminum film 18 formed on the aluminum base 12 is referred to as “cutting trace”.

By performing an anodizing process and an etching process for pretreatment before the satin treatment, cutting traces can be reduced. That is, cutting traces can be reduced by once anodizing the surface of the aluminum base 12 and removing the formed anodized film by etching. In this anodic oxidation step for pretreatment, an aqueous sulfuric acid solution is preferably used as the electrolytic solution, and in the etching step for pretreatment, an aqueous phosphoric acid solution is preferably used as the etching solution. Of course, also for the aluminum base material 12 that has been subjected to cold drawing and mirror-finished by cutting by cutting, an anodizing process and an etching process for pretreatment are performed, so that the cutting traces are formed on the surface of the aluminum base material 12. Can be more reliably suppressed.

Note that the above-described cutting trace is considered to be etching unevenness caused by a work-affected layer formed on the surface of the aluminum base 12 by mirror finishing by cutting with a bite. Therefore, the problem that the cut mark is formed by the satin treatment is not limited to the cutting by cutting, and is a common problem when using the aluminum base material 12 that has been subjected to mirror finishing accompanied by the formation of a work-affected layer. This can be solved by performing an anodizing process and an etching process for pretreatment. Among mirror finishes, mechanical polishing such as cutting and grinding (Mechanical Polishing: MP), and chemical mechanical polishing (CMP) that uses both chemical polishing and mechanical polishing, form a work-affected layer. Accompany. The mechanical polishing includes, for example, buffing, belt polishing, and blast polishing. Note that, in the case where electropolishing is used in combination with mechanical polishing instead of chemical polishing, a work-affected layer is similarly formed. In this specification, “mechanical mirror finishing” includes not only MP and CMP, but also processing using a combination of electrolytic polishing and mechanical polishing.

Before the matte treatment, a step of etching the surface of the aluminum base 12 using an alkaline etching solution (hereinafter sometimes referred to as “base surface etching step”) may be further performed. By the substrate surface etching process using an alkaline etching solution, at least a part of the work-affected layer of the aluminum substrate 12 that may cause cutting marks can be removed.

The alkaline etching solution contains, for example, an inorganic base (inorganic alkali) or an organic base (organic alkali). Inorganic bases include, for example, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide and the like. The organic base includes, for example, a compound having an amino group. Organic bases include, for example, 2-aminoethanol (ethanolamine), primary alkanolamine, dimethylbis (2-hydroxy) ethyl, and the like. The pH of the alkaline etching solution is, for example, 10 or more and 12 or less. The alkaline etching liquid is not limited to the above, and for example, a known alkaline cleaning liquid may be used.

The substrate surface etching step may be performed, for example, before the anodizing step and the etching step for pretreatment. The substrate surface etching step may be performed, for example, instead of the anodizing step and the etching step for pretreatment. Since the substrate surface etching step uses an alkaline etching solution, it can also serve as a degreasing step.

The number of steps can be reduced by performing the substrate surface etching step in place of the anodizing step and the etching step for pretreatment. The number of steps can also be reduced when the substrate surface etching step also serves as a degreasing step. An aluminum substrate having a surface with less unevenness can be obtained with fewer steps. A mold for forming an antireflection film having an appropriate antiglare function can be efficiently produced. The production yield of the antireflection film having an appropriate antiglare function can be improved.

Next, as shown in FIG. 1C, an inorganic material layer 16 is formed on the surface of the aluminum substrate 12, and an aluminum film 18 is formed on the inorganic material layer 16, thereby producing the mold substrate 10. To do.

On the surface of the aluminum film 18, a structure reflecting an inverted antiglare structure formed by subjecting the surface of the aluminum substrate 12 to a matte finish is formed. Here, the structure formed in the aluminum film 18 is also called an inverted antiglare structure. The inverted antiglare structure formed on the surface of the aluminum film 18 has substantially the same structure as the inverted antiglare structure formed on the surface of the aluminum substrate 12. Therefore, the inverted anti-glare structure formed on the surface of the aluminum film 18 has a plurality of macro convex portions 18p and a plurality of macro concave portions 18g. The macro convex portion 18p is substantially surrounded by the macro concave portion 18g, and the macro concave portion 18g exists like a groove that defines the outer periphery of the macro convex portion 18p.

As a material of the inorganic material layer 16, for example, tantalum oxide (Ta ₂ O ₅ ) or silicon dioxide (SiO ₂ ) can be used. The inorganic material layer 16 can be formed by sputtering, for example. When a tantalum oxide layer is used as the inorganic material layer 16, the thickness of the tantalum oxide layer is, for example, 200 nm.

The thickness of the inorganic material layer 16 is preferably 100 nm or more and less than 500 nm. If the thickness of the inorganic material layer 16 is less than 100 nm, defects (mainly voids, that is, gaps between crystal grains) may occur in the aluminum film 18 in some cases. Further, when the thickness of the inorganic material layer 16 is 500 nm or more, the aluminum base 12 and the aluminum film 18 are easily insulated from each other depending on the surface state of the aluminum base 12. In order to anodize the aluminum film 18 by supplying current to the aluminum film 18 from the aluminum substrate 12 side, it is necessary that a current flow between the aluminum substrate 12 and the aluminum film 18. If a configuration is adopted in which current is supplied from the inner surface of the cylindrical aluminum substrate 12, it is not necessary to provide an electrode on the aluminum film 18, so that the aluminum film 18 can be anodized over the entire surface, and the current is increased as the anodization proceeds. Therefore, the aluminum film 18 can be uniformly anodized over the entire surface without causing a problem that it is difficult to be supplied.

Further, in order to form the thick inorganic material layer 16, it is generally necessary to lengthen the film formation time. When the film formation time is lengthened, the surface temperature of the aluminum base 12 is unnecessarily increased. As a result, the film quality of the aluminum film 18 is deteriorated, and defects (mainly voids) may occur. If the thickness of the inorganic material layer 16 is less than 500 nm, the occurrence of such a problem can be suppressed.

The aluminum film 18 is, for example, a film formed of aluminum having a purity of 99.99 mass% or more (hereinafter, also referred to as “high-purity aluminum film”) as described in Patent Document 3. The aluminum film 18 is formed using, for example, a vacuum deposition method or a sputtering method. The thickness of the aluminum film 18 is preferably in the range of about 500 nm or more and about 1500 nm or less, for example, about 1 μm.

As the aluminum film 18, an aluminum alloy film described in International Publication No. 2013/0183576 may be used instead of the high-purity aluminum film. The aluminum alloy film described in International Publication No. 2013/0183576 contains aluminum, a metal element other than aluminum, and nitrogen. In the present specification, the “aluminum film” includes not only a high-purity pure aluminum film but also an aluminum alloy film described in International Publication No. 2013/0183576. For reference purposes, the entire disclosure of WO2013 / 0183576 is incorporated herein by reference.

When using the aluminum alloy film, a mirror surface with a reflectance of 80% or more can be obtained. The average grain size of the crystal grains constituting the aluminum alloy film as viewed from the normal direction of the aluminum alloy film is, for example, 100 nm or less, and the maximum surface roughness Rmax of the aluminum alloy film is 60 nm or less. The content rate of nitrogen contained in the aluminum alloy film is, for example, not less than 0.5 mass% and not more than 5.7 mass%. The absolute value of the difference between the standard electrode potential of a metal element other than aluminum contained in the aluminum alloy film and the standard electrode potential of aluminum is 0.64 V or less, and the content of the metal element in the aluminum alloy film is 1.0 mass. % Or more and 1.9 mass% or less is preferable. The metal element is, for example, Ti or Nd. However, the metal element is not limited to this, and other metal elements whose absolute value of the difference between the standard electrode potential of the metal element and the standard electrode potential of aluminum is 0.64 V or less (for example, Mn, Mg, Zr, V, and Pb). Furthermore, the metal element may be Mo, Nb, or Hf. The aluminum alloy film may contain two or more of these metal elements. The aluminum alloy film is formed by, for example, a DC magnetron sputtering method. The thickness of the aluminum alloy film is also preferably in the range of about 500 nm to about 1500 nm, for example, about 1 μm.

Here, with reference to FIGS. 3A to 3D, the inverted antiglare structure will be described in detail. FIG. 3A is a laser microscope image (full scale 15 μm in the microscopic image) of the surface of the aluminum substrate 12 having an inverted antiglare structure formed by the satin treatment, and FIG. It is a SEM image (full scale 10 micrometers in a SEM image) when the surface of the aluminum base material 12 which has the inverted anti-glare structure formed by the process is observed from a perpendicular direction. FIG. 3 (a) is an observation of the surface of the aluminum substrate 12 subjected to a matte treatment under conditions of an anodic oxidation temperature of 10 ° C. and an anodic oxidation time of 5 minutes in an experimental example described later. The surface of the aluminum base material 12 that has been subjected to a satin treatment under the conditions of an anodic oxidation temperature of 10 ° C. and an anodic oxidation time of 3 minutes in an experimental example described later is observed. FIG. 3C is a schematic plan view of the inverted antiglare structure, and FIG. 3D is a schematic perspective view of the inverted antiglare structure.

As shown in FIGS. 3A to 3D, the inverted anti-glare structure formed by the satin treatment has a plurality of macro convex portions 18p and a plurality of macro concave portions 18g. The macro convex portion 18p is substantially surrounded by the macro concave portion 18g, and the macro concave portion 18g exists like a groove that defines the outer periphery of the macro convex portion 18p.

When viewed from the normal direction of the surface, the plurality of macro convex portions 18p have a substantially polygonal outer shape, but regularity is not seen in the arrangement. The two-dimensional size (area circle equivalent diameter) when viewed from the normal direction of the surface of the macro convex portion 18p is about 200 nm or more and 30 μm or less. From the microscopic image of FIG. 3A and the SEM image of FIG. 3B, the two-dimensional size when viewed from the normal direction of the surface of the macro convex portion 18p is about 1 μm or more and about 5 μm or less. It can be estimated. Further, the upper surface of the macro convex portion 18p is substantially flat.

The width of the macro concave portion (groove) 18g that substantially surrounds the macro convex portion 18p is about one-tenth to one-fifth of the two-dimensional size of the macro convex portion 18p. . The average value of the distance between adjacent macro concave portions 18g (average inter-adjacent distance AD _int ) is approximately equal to the average value of the two-dimensional size when viewed from the normal direction of the surface of the macro convex portion 18p. Can think. Here, since the macro concave portion 18g is formed so as to substantially surround the macro convex portion 18p, the adjacent macro concave portion 18g defines the two-dimensional size of the macro convex portion 18p. The macro concave portions 18g adjacent in the cross section in the direction are meant. Therefore, the average distance AD _int between the adjacent portions is approximately equal to the sum of the average value of the two-dimensional size of the macro-shaped convex portion 18p and the average value of the width of the macro-shaped concave portion 18g. The depth AD _depth of the macro concave portion 18g is, for example, 20 nm or more and 500 nm or less, but may be 20 nm or more and less than 5 μm.

After forming the inverted anti-glare structure, anodic oxidation and etching are alternately repeated to form the inverted moth-eye structure, whereby the moth-eye mold 100 shown in FIG. 1D is obtained. That is, in the process of forming the inverted moth-eye structure, the surface of the aluminum film 18 is anodized to form a porous alumina layer 14 having a plurality of micro recesses 14p, and then the porous alumina layer 14 Including a step of expanding a plurality of micro concave portions 14p of the porous alumina layer 14 by contacting with an etching solution, and a step of growing a plurality of micro concave portions 14p by further anodizing thereafter. To do. The electrolytic solution used for anodization is, for example, an aqueous solution containing an acid selected from the group consisting of oxalic acid, tartaric acid, phosphoric acid, sulfuric acid, chromic acid, citric acid, and malic acid. As an etchant, an aqueous solution of an organic acid such as formic acid, acetic acid, or citric acid or an aqueous solution of sulfuric acid, a mixed aqueous solution of chromic phosphoric acid, or an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be used.

It is preferable that the series of steps of repeating anodization and etching end with the anodization step. By ending with the anodizing step (the subsequent etching step is not performed), the bottom of the micro concave portion 14p can be reduced. A method for forming such an inverted moth-eye structure is disclosed, for example, in WO 2006/059686 by the applicant. For reference, the entire disclosure of WO 2006/059686 is incorporated herein by reference.

For example, an anodic oxidation step (electrolytic solution: oxalic acid aqueous solution (concentration 0.3 mass%, liquid temperature 10 ° C.), applied voltage: 80 V, application time: 55 seconds) and etching step (etching solution: phosphoric acid aqueous solution (10 mass%, 30 ° C.) ) And etching time: 20 minutes) alternately, a plurality of times (for example, 5 times: anodization is 5 times and etching is 4 times), thereby providing a micro concave portion 14p as shown in FIG. The moth-eye mold 100 having the porous alumina layer 14 is obtained. As explained with reference to FIG. 17C, the porous alumina layer 14 formed under the conditions exemplified here has D _p = D _int of 10 nm or more and less than 500 nm, and D _depth of 10 nm or more and 1000 nm (1 μm). It has a structure in which micro recesses 14p of less than about are densely and irregularly arranged. The micro concave portion 14p has a substantially conical shape and is adjacent to form a collar portion.

The inverted moth-eye structure composed of the micro recesses 14p is formed so as to be superimposed on the antiglare structure. Therefore, as schematically shown in FIG. 1 (d), the micro concave portion 14p formed in the macro convex portion 18p constituting the antiglare structure and the micro concave portion 14p formed in the macro concave portion 18g are provided. Exists. The micro concave portion 14p formed in the macro concave portion 18g is deeper than the micro concave portion 14p formed in the macro convex portion 18p.

A barrier layer is formed under the micro concave portion 14p. The porous alumina layer 14 includes a porous layer having the micro concave portion 14p and a barrier layer (under the aluminum film side) (on the aluminum film side). The bottom of the recess 14p). It is known that the interval between the adjacent micro concave portions 14p (center-to-center distance) corresponds to approximately twice the thickness of the barrier layer and is approximately proportional to the voltage during anodization. Under the porous alumina layer 14, an aluminum remaining layer 18 r that has not been anodized in the aluminum film 18 is present.

4A (a) shows an SEM image (full scale 10 μm in the SEM image) when the surface of the aluminum film 18 of the mold base 10 is observed from the vertical direction, and FIG. 4A (b) shows the moth-eye mold 100. 2 shows an SEM image (full scale 10 μm in the SEM image) when the surface of the porous alumina layer 14 having an inverted moth-eye structure is observed from the vertical direction. The mold base 10 of FIG. 4A (a) has a thickness on an aluminum base 12 having an inverted antiglare structure formed by a satin treatment under the same conditions as the aluminum base 12 shown in FIG. 3 (b). Is a mold substrate 10 in which a tantalum oxide layer having a thickness of about 200 nm and an aluminum film (aluminum alloy film) 18 having a thickness of about 800 nm and containing Ti and N are formed. The Ti content of the aluminum film 18 is about 1.0 mass%, the N content is about 1.2 mass% or more and about 2.0 mass% or less, and the remainder is Al and inevitable impurities. The moth-eye mold 100 shown in FIG. 4A (b) uses the mold base 10 manufactured under the same conditions as the mold base 10 shown in FIG. 4A (a), and is anodized and etched under the conditions exemplified above. The moth-eye mold 100 is produced by alternately repeating the above (anodization is repeated 5 times and etching is repeated 4 times).

4A (a) and FIG. 3 (b), a structure reflecting the inverted anti-glare structure of the surface of the aluminum base 12 is formed on the surface of the aluminum film 18. 4A (b) and 4A (a), the porous alumina layer 14 of the moth-eye mold 100 has a surface structure in which the inverted moth-eye structure is superimposed on the inverted anti-glare structure. have.

Thus, according to the method for manufacturing the moth-eye mold 100 of Embodiment 1 according to the present invention, the moth-eye mold 100 capable of forming an antireflection film having an antiglare function can be manufactured. The antiglare function of the antireflection film formed using the moth-eye mold 100 will be described in detail later by showing experimental examples.

(Embodiment 2)
The mold manufacturing method according to the second embodiment of the present invention is different from the mold manufacturing method according to the first embodiment in the step (B). The mold manufacturing method according to the second embodiment includes a step (process (B ′)) of treating the surface of the aluminum base with an alkaline etching solution instead of the process (B) of the mold manufacturing method according to the first embodiment. Include. That is, in the second embodiment, the surface of the aluminum base is treated with an alkaline etching solution instead of an aqueous solution containing a salt of hydrogen fluoride and ammonium.

In the step of treating the surface of the aluminum base material with an alkaline etching solution, at least a part of the work-affected layer of the aluminum base material can be removed. As a separate process from the satin treatment, there is no need to perform a step of etching the surface of the aluminum base material, or an anodizing step and an etching step for pretreatment. Moreover, the process of carrying out the satin treatment of the surface of an aluminum base material with an alkaline etching liquid can serve as a degreasing process. According to the mold manufacturing method of Embodiment 2, a mold for forming an antireflection film having an appropriate antiglare function can be manufactured without increasing the number of manufacturing steps.

A method of manufacturing a mold according to Embodiment 2 and a structure of a mold manufactured by such a manufacturing method will be described with reference to FIGS. 4B (a) to 4 (c). The mold manufacturing method according to the second embodiment may be the same as the mold manufacturing method according to the first embodiment described with reference to FIGS. 1 to 4A except for the step (B ′). The description of the method of manufacturing the mold according to the first embodiment and the structure substantially the same as the structure of the mold manufactured by such a manufacturing method described with reference to FIGS. 1 to 4A will be omitted.

4B (a) is a cross-sectional view schematically showing the surface structure of the aluminum base 12 having an inverted antiglare structure, and FIG. 4B (b) shows the inorganic material layer 16 and the surface of the aluminum base 12 on the surface. FIG. 4B (c) is a schematic cross-sectional view of the mold base 10 on which the aluminum film 18 is formed, and FIG. 4B (c) shows the surface of the aluminum base 12 having an inverted antiglare structure formed by a satin treatment with an alkaline etchant. It is a laser microscope image.

By subjecting the surface of the aluminum base 12 to a satin finish using an alkaline etching solution, an anti-glare structure inverted to the surface 12s of the aluminum base 12 is formed as shown in FIGS. 4B (a) to 4 (c). Is done. The macro concave portion 12g is, for example, a region (for example, substantially including a circle) closed by a curve when viewed from the normal direction of the surface. The shape of the macro recess 12g may be, for example, a substantially hemisphere. The two-dimensional size (area circle equivalent diameter) of the macro concave portion 12g when viewed from the normal direction of the surface is, for example, not less than 500 nm and not more than 20 μm. An inverted antiglare structure is formed by a plurality of macro concave portions 12g having different two-dimensional sizes.

When a satin treatment is performed using an aqueous solution containing a salt of hydrogen fluoride and ammonium in the method for producing a mold according to Embodiment 1 of the present invention, as described above with reference to FIGS. 3 (a) to 3 (d), Macro

concave portions

12g and 18g having a substantially polygonal outer shape were formed. The reason why the macro concave portion 12g is a region closed by a plurality of substantially straight lines is considered to be due to the formation of the macro concave portion 12g corresponding to the crystal grain boundary of the aluminum base 12.

The crystal grain boundary is an interface existing between adjacent crystal grains in a polycrystal (eg, metal). In the present specification, the crystal grains of the aluminum base material include crystal grains and subgrains, and the crystal grain boundaries of the aluminum base material include grain boundaries and sub-crystals. It is assumed to include a grain boundary. In the present specification, the crystal grains of the aluminum substrate include those having a size of about several tens of μm to about several mm.

On the other hand, when a satin treatment is performed using an alkaline etching solution in the manufacturing method of the mold of Embodiment 2, for example, a macro concave portion 12g having a region closed by a curve is formed. When an alkaline etching solution is used, it is considered that a macro concave portion 12g can be formed without being greatly affected by the crystal grain boundary of the aluminum base 12.

In general, when an acidic etching solution is used, macroscopic recesses tend to be formed corresponding to the crystal grain boundaries of the aluminum substrate to be etched, whereas when an alkaline etching solution is used, etching is performed. There was a tendency that macro concave portions were formed without being affected by the crystal grains and crystal grain boundaries of the aluminum base material. When the matte treatment is performed using an alkaline etching solution, it is considered that the occurrence of uneven etching due to crystal grains and crystal grain boundaries of the aluminum base 12 can be suppressed. In a film formed by a mold manufactured through a satin treatment with an alkaline etching solution, the occurrence of unevenness due to crystal grains and crystal grain boundaries can be suppressed. Therefore, the mold manufacturing method of Embodiment 2 may be suitably used for manufacturing a mold for forming an antireflection film.

However, as will be described later with reference to experimental examples, depending on the type of alkaline etching solution, an uneven shape (sometimes referred to as a pattern) that is larger than a macro recess is formed on the surface of the aluminum substrate. There was also. As will be described later, for example, by appropriately adjusting the pH of the alkaline etching solution and the concentration of the base contained in the alkaline etching solution, it is possible to suppress the generation of uneven shapes larger than the macro concave portions.

In the present specification, the step of treating the surface of the aluminum base material with the matte surface refers to a step of forming an inverted antiglare structure on the surface of the aluminum base material. As will be described later with reference to experimental examples, in order to form an antireflection film having an appropriate anti-glare function, the surface of the aluminum substrate is subjected to a matte treatment with an alkaline etchant. The arithmetic average roughness Ra is preferably 50 nm or more and 200 nm or less, for example.

The alkaline etching solution contains, for example, an inorganic base (inorganic alkali) or an organic base (organic alkali). Inorganic bases include, for example, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide and the like. The organic base includes, for example, a compound having an amino group. Organic bases include, for example, 2-aminoethanol (ethanolamine), primary alkanolamine, dimethylbis (2-hydroxy) ethyl, and the like. The alkaline etching liquid is not limited to the above, and for example, a known alkaline cleaning liquid may be used. By using a known alkaline cleaning liquid, it is possible to suppress the labor and / or cost increase in the satin treatment process.

The mold manufacturing method according to the embodiment of the present invention is not limited to using an alkaline etching solution, and an acidic etching solution may be used. For example, depending on conditions such as the composition of the aluminum substrate and / or the processing method, crystal grains and crystal grain boundaries of the aluminum substrate may not be noticeable even when an acidic etching solution is used. In addition, by appropriately adjusting the conditions such as the type of acid and / or the acid concentration contained in the acidic etching solution, it is possible to suppress the occurrence of etching unevenness due to the crystal grains and grain boundaries of the aluminum substrate. Is possible.

(Production method of antireflection film and mold structure produced by such production method)
Next, with reference to FIG. 5, a method of manufacturing an antireflection film using the moth-eye mold 100 manufactured by the mold manufacturing method of Embodiment 1 or Embodiment 2 will be described. FIG. 5 is a schematic cross-sectional view for explaining a method for producing an antireflection film by a roll-to-roll method.

First, a cylindrical moth-eye mold 100 is prepared. The cylindrical moth-eye mold 100 is manufactured by the above-described manufacturing method.

As shown in FIG. 5, ultraviolet light (UV) is irradiated to the ultraviolet curable resin 32 ′ while the workpiece 42 having the ultraviolet curable resin 32 ′ applied to the surface thereof is pressed against the moth-eye mold 100. The cured resin 32 ′ is cured. As the ultraviolet curable resin 32 ′, for example, an acrylic resin can be used. The workpiece 42 is, for example, a TAC (triacetyl cellulose) film. The workpiece 42 is unwound from an unillustrated unwinding roller, and then an ultraviolet curable resin 32 ′ is applied to the surface by, for example, a slit coater. The workpiece 42 is supported by

support rollers

46 and 48 as shown in FIG. The

support rollers

46 and 48 have a rotation mechanism and convey the workpiece 42. The cylindrical moth-eye mold 100 is rotated in the direction indicated by the arrow in FIG. 5 at a rotational speed corresponding to the conveying speed of the workpiece 42.

Thereafter, by separating the moth-eye mold 100 from the workpiece 42, a cured product layer 32 to which the uneven structure (inverted moth-eye structure) of the moth-eye mold 100 is transferred is formed on the surface of the workpiece 42. . The workpiece 42 having the cured product layer 32 formed on the surface is wound up by a winding roller (not shown).

6 (a) and 6 (b) show SEM images of the antireflection film produced as described above. 6A and 6B are SEM images of an antireflection film having an antiglare function according to an embodiment of the present invention, and FIG. 6A is an SEM when the surface of the antireflection film is observed from the vertical direction. FIG. 6B is an SEM image (full scale 3 μm in the SEM image) when the cross section and the surface of the antireflection film are observed from an oblique direction.

As can be seen from FIGS. 6A and 6B, the moth-eye structure is formed so as to overlap the anti-glare structure. The anti-glare structure is constituted by a macro concave portion and a macro convex portion obtained by inverting the macro convex portion 18p and the macro concave portion 18g formed by the satin treatment. The two-dimensional size when viewed from the normal direction of the surface of the macro concave portion constituting the antiglare structure exemplified here is about 1 μm or more and about 5 μm or less, and the macro convex portion constituting the antiglare structure is The size is about 1/10 to 1/5 of the two-dimensional size. Moreover, the height of the macro convex part which comprises an anti-glare structure is about 200 nm or more and about 500 nm or less. For the micro-convex portion constituting the moth-eye structure, the two-dimensional size and the distance between adjacent portions (corresponding to D _p = D _int ) is about 200 nm, and the height (corresponding to D _depth ) is about 200 nm.

7A to 7C, the structure of the antireflection film 32 having the antiglare function according to the embodiment of the present invention will be described. FIGS. 7A to 7C are schematic views of the antireflection film 32 having an antiglare function according to the embodiment of the present invention. FIG. 7A is a view when the surface of the antireflection film 32 is observed from the vertical direction. FIG. 7B is a schematic diagram when the surface of the antireflection film 32 is observed from an oblique direction, and FIG. 7C is a schematic diagram of a cross section of the antireflection film 32.

7A to 7C, the plurality of micro convex portions constituting the moth-eye structure includes micro

convex portions

32p and 32g. The micro convex portion 32p is formed in a macro concave portion constituting the anti-glare structure, and the micro convex portion 32g is formed in a macro convex portion constituting the anti-glare structure. Therefore, the micro convex portion 32g is higher than the micro convex portion 32p, and is arranged so as to substantially surround the micro convex portion 32p formed in the macro convex portion. This corresponds to the fact that in the process of manufacturing the moth-eye mold 100, in the inverted anti-glare structure formed by the satin treatment, the macro convex portion 18p is substantially surrounded by the macro concave portion 18g. . From the microscopic images of FIGS. 6A and 6B, it can be seen that microscopic convex portions higher than those are formed so as to surround a large number of micro convex portions.

Next, the diffuse reflection characteristics of the antireflection film having the antiglare function according to the embodiment of the present invention will be described with reference to FIG. FIG. 8A is a graph showing the measurement result of the light distribution of diffuse reflection by the antireflection film having the antiglare function, and FIG. 8B is a schematic diagram showing the measurement system of the light distribution of diffuse reflection. FIG. The diffuse reflected light does not specifically exclude scattered light.

In FIG. 8 (a), EX. 1 shows a light distribution of diffuse reflection light of an antireflection film having an antiglare function according to an embodiment of the present invention. This antireflection film is formed by using an aluminum substrate 12 that has been subjected to a satin treatment at 10 ° C. for 4 minutes with an aqueous solution containing ammonium hydrogen fluoride (the concentration of ammonium hydrogen fluoride is 4 mass%) as in the experimental examples described later. It is an anti-glare film formed by using. CNV. 1 shows the distribution of diffusely reflected light of an antireflection film having an antiglare structure having a continuous corrugated surface without a flat portion, which is formed by using an electrodeposition resin containing a matting agent described above with reference to FIG. The light distribution is shown. CNV. One antiglare structure has a two-dimensional size of 10 μm to 30 μm and a height of 500 nm to 1000 nm.

As shown in FIG. 8B, the light distribution of the diffuse reflected light is irradiated with light at an incident angle of 5 ° to the sample film, and the diffuse reflected light is distributed at a light receiving angle of 0 ° to 25 °. Distribution was measured. Specifically, each sample film was attached to a glass plate, and the light distribution was measured with a goniophotometer. As a goniophotometer, GP-200 manufactured by Murakami Color Research Laboratory was used. Here, the light distribution with the common logarithm of relative diffuse reflectance (%) normalized with the incident angle of 5 °, the light receiving angle on the horizontal axis, and the maximum value of diffuse reflected light intensity at 80% is plotted on the vertical axis. A distribution curve is shown. The same applies to the orientation distribution curves shown below unless otherwise specified.

CNV. The light distribution of 1 takes a peak value at a light receiving angle of 5 °, and falls within a range of 0 ° to 10 °. CNV. The light distribution distribution curve of 1 is relatively steep as a whole, and the relative diffuse reflectance (%) decreases monotonously as it deviates from the light receiving angle of 5 °. Although the conventional antireflection film (CNV.1) has a low haze value of about 3, the specular reflectivity is low and the image is blurred. Therefore, in particular, when used for a high-definition image display panel, the impression of lowering the display quality is given.

On the other hand, EX. 1 has a peak value at a light receiving angle of 5 °, EX. In a range of a light receiving angle of about 3 ° to about 4 ° and a light receiving angle of about 6 ° to about 7 °. No. 1 relative diffuse reflectance (%) changes in CNV. EX. At a light receiving angle of less than about 3 ° and a light receiving angle of more than about 7 °. No. 1 relative diffuse reflectance (%) changes in CNV. It is more gradual than the change in relative diffuse reflectance (%) of 1. EX. 1 has a haze value of about 15, CNV. Although it is higher than 1, it has excellent specular reflectivity. As will be described later with reference to experimental examples, the antireflection film (EX.1) having the antiglare structure according to the embodiment of the present invention has a light receiving angle of 0 ° in that the slope of the light distribution curve changes discontinuously. Since it has a characteristic diffuse reflection characteristic that it is in the range of 10 ° or less and the relative diffuse reflectance (%) is in the range of 1% or more and 10% or less, the conventional antireflection film (CNV) .1) has higher specular reflectivity and moderate diffuse reflection performance (for example, a haze value of about 7 or more and about 24 or less). The antireflection film (EX.1) according to the embodiment of the present invention suppresses the image from being blurred more than necessary even when used for a high-definition display exceeding 300 ppi, for example, and the reflection is suppressed with high display quality. An indication can be provided.

Hereinafter, with reference to experimental examples, the moth-eye mold and the moth-eye mold manufacturing method according to the embodiment of the present invention will be described in more detail.

[Selection of aluminum substrate]
Al—Mg-based aluminum alloy JIS A5052 was used as the Al—Mg-based aluminum alloy. JIS A5052 has the following composition (mass%).

Si: 0.25% or less, Fe: 0.40% or less, Cu: 0.10% or less, Mn: 0.10% or less, Mg: 2.2 to 2.8%, Cr: 0.15 to 0 .35%, Zn: 0.10% or less, others: individual 0.05% or less, overall 0.15% or less, balance: Al

A mold base was prepared using a cylindrical aluminum base formed of an aluminum alloy of JIS A5052. Here, the aluminum base material which performed the mirror surface process by a bite cutting was used, without performing cold drawing processing to the aluminum base material produced by the boat hall method. The mold base was produced by the method described above with reference to FIG. A tantalum oxide layer having a thickness of 200 nm was formed as the inorganic material layer, and an aluminum alloy film containing Ti and N having a thickness of 800 nm was formed as the aluminum film. The Ti content of the aluminum alloy film is about 1.0 mass%, the N content is about 1.2 mass% or more and about 2.0 mass% or less, and the remainder is Al and inevitable impurities. The same applies to the experimental examples shown below unless otherwise specified.

¡Chemical finish was applied to the aluminum substrate. As an etching solution for the satin treatment, an aqueous solution containing ammonium hydrogen fluoride (a concentration of ammonium hydrogen fluoride was 4 mass%) was used. The obtained macro uneven structure was rougher than necessary, had high diffuse reflection performance, and could not obtain an appropriate antiglare function.

Therefore, when the conditions of the satin treatment were mild (processing time was shortened, the concentration of the processing solution was lowered, and the processing temperature was lowered), unevenness was observed on the surface. Specifically, a region having a low diffuse reflection performance and a region having a high diffuse reflection performance occurred on the order of several centimeters.

Based on the above, it was judged that an aluminum substrate formed of an Al—Mg based aluminum alloy was unsuitable.

Al—Mg—Si based aluminum alloy JIS A6063 was used as the Al—Mg—Si based aluminum alloy. JIS A6063 has the following composition (mass%).

Si: 0.20 to 0.60%, Fe: 0.35% or less, Cu: 0.10% or less, Mn: 0.10% or less, Mg: 0.45 to 0.9%, Cr: 0. 10% or less, Zn: 0.10% or less, Ti: 0.10% or less, Other: Individual is 0.05% or less, the whole is 0.15% or less, the balance: Al

A mold base material was prepared using a cylindrical aluminum base material formed of an aluminum alloy of JIS A6063. Here, the aluminum base material which performed the mirror surface process by a bite cutting was used, without performing cold drawing processing to the aluminum base material produced by the boat hall method.

The satin treatment was carried out with an aqueous solution containing ammonium hydrogen fluoride on this aluminum base material. Except for the seam portion of the aluminum base material produced by the boat hole method, there was no unevenness in the surface, and a macro uneven structure having an appropriate anti-glare function could be obtained.

Next, after performing cold drawing and mirror finishing by cutting with a bite, a satin treatment was performed with an aqueous solution containing ammonium hydrogen fluoride, and the seam portion was not noticeable and there was no unevenness in the surface. A macro uneven structure having an appropriate anti-glare function was obtained.

For these reasons, the aluminum base material is preferably an Al—Mg—Si based aluminum alloy, particularly one formed of JIS A6063. In particular, an aluminum base material that has been subjected to cold drawing is preferable because the joints are not noticeable. In addition, even if it is a hot extrusion method, since the aluminum base material produced by the mandrel method has no seam, it can be used suitably similarly to the aluminum base material produced by the cold drawing method.

FIGS. 9A to 9C show SEM images (5,000 times, full scale 10 μm in the SEM image) of the surface of the aluminum base material treated with an aqueous solution containing ammonium hydrogen fluoride. The SEM image was acquired using a field emission scanning electron microscope (Hitachi S-4700). The same applies to the following SEM images.

FIG. 9A is an SEM image of the surface of a JIS A6063 aluminum substrate that has been cold drawn, and FIG. 9B is an aluminum base of JIS A6063 that has not been cold drawn. FIG. 9C is an SEM image of the surface of the material, and FIG. 9C is an SEM image of the surface of the aluminum substrate of JIS A5052 that has not been cold drawn. In either case, the time for the satin treatment with the aqueous solution containing ammonium hydrogen fluoride is 45 seconds. However, for FIG. 9A, degreasing and washing were performed as pretreatment. 9B and 9C, anodization and etching were performed as pretreatment. The effects of these preprocessing will be described later.

As is clear from a comparison between FIGS. 9A and 9B and FIG. 9C, the surface of the aluminum substrate of JIS A5052 (FIG. 9C) is the surface of the aluminum substrate of JIS A6063. Compared with (FIGS. 9A and 9B), a very rough uneven structure is formed. Accordingly, as the aluminum base material, an Al—Mg—Si based aluminum alloy, particularly JIS A6063 is preferable.

[Degreasing / Washing]
When a satin finish is applied to an aluminum substrate of JIS A6063 that has been cold drawn, macro unevenness may occur on the surface of the aluminum substrate. In order to prevent the occurrence of macro unevenness, degreasing and washing were studied as pretreatment for the satin treatment.

For degreasing, an aqueous solution having a concentration of 3% by mass of an inorganic alkaline detergent (LG manufactured by Yokohama Oil & Fat Co., Ltd.) was used, and the sample was immersed in this aqueous solution at 40 ° C. for 10 minutes. Thereafter, the sample was washed with water by immersing it in pure water for 10 minutes. Samples with different times for leaving the samples after washing in the atmosphere (0 minutes, 5 minutes, 15 minutes, 22 hours) were prepared, and then subjected to a satin treatment.

No unevenness occurred on the surface of the aluminum base material that was subjected to the satin treatment without being completely dried after washing with water (conditions C1 and C2 in Table 1 below). Unevenness was observed on the entire surface of the aluminum substrate (Condition C4). Slight unevenness was observed when the standing time was 15 minutes (condition C3).

When degreased, washed with water and dried, solid aluminum hydroxide is deposited on the surface of the aluminum base material and fixed. This aluminum hydroxide is considered to cause unevenness as a result of hindering the treatment liquid from acting on the surface of the aluminum substrate. Therefore, it is preferable to perform the satin treatment after the water washing and before the surface of the aluminum base material is dried. Of course, if it is washed with water again after drying and then subjected to a satin treatment before drying, unevenness can be prevented. After the water washing step, it is preferable to perform the satin treatment before 15 minutes have passed.

In addition, as a degreasing agent, a surfactant (Nikkasan Clean manufactured by Nikka Chemical Co., Ltd.) or sulfuric acid may be used.

[Sashimi processing time]
In order to produce a moth-eye mold for forming an antireflection film having an antiglare function, the results of studying the relationship between the satin treatment time and the degree of diffuse reflection performance will be described. In the following experiment, an aluminum substrate of JIS A6063 that was cold-drawn was used. As an etching solution for the satin treatment, an aqueous solution containing ammonium hydrogen fluoride (a concentration of ammonium hydrogen fluoride was 4 mass%) was used.

A mold sample was produced in which the matte treatment time for the aluminum substrate was changed from 5 seconds to 3 minutes. The satin treatment temperature was 35 ° C. In addition, before performing a satin process, it degreased | degreased using surfactant and performed the satin process until 15 minutes passed after water washing.

After applying a release agent (Optool DSX, manufactured by Daikin Industries, Ltd.) to the surface of the aluminum base material that has been subjected to a satin finish treatment, an acrylic UV curable resin is applied and UV light is transferred to the PET film. Irradiated to cure. The light distribution was measured by the method described with reference to FIG. 8B using the obtained sample film having a macro uneven structure. As in the sample film used here, a film that does not have a moth-eye structure and has only an antiglare structure is sometimes referred to as an antiglare film.

Also, the light distribution of various anti-glare films (REF_No. 1 to No. 4) used by the applicant for television applications was also evaluated as a sample film for reference. The anti-glare film used here is formed by applying a coating agent (resin) in which fine particles are dispersed on the surface of the film, and depends on the surface having macro unevenness formed by the fine particles. The antiglare function is exhibited by diffuse reflection and diffuse reflection (including scattering) at the interface between the coating agent and the fine particles. On the other hand, the antireflection film (EX.1) of the embodiment according to the present invention described with reference to FIG. 8A and the antiglare film described below exhibit an antiglare function only by a surface structure having macro unevenness. To do.

FIG. 10A shows the measurement result of the light distribution of diffuse reflected light. Similarly to FIG. 8A, FIG. 10A shows the relative diffuse reflectance (%) normalized by setting the incident angle to 5 °, the light receiving angle to the horizontal axis, and the maximum value of diffuse reflected light intensity to 80%. The light distribution curve is shown with the common logarithm on the vertical axis.

From the result of FIG. 10A, it can be seen that the ratio of the diffuse reflected light having a large light receiving angle increases as the time of the satin treatment increases. That is, the antiglare function becomes higher as the pear-finishing time becomes longer. The haze value when the processing time is 37 seconds is about 7, the haze value when about 45 seconds is about 10, the haze value when about 75 seconds is about 24, and the haze value when about 90 seconds is about 40. . REF_No. The haze value of 1 is 2, and no. The haze value of 3 is about 40, which is the largest among the REFs. The haze value was determined from (diffuse transmittance / total light transmittance) × 100 using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

When the satin treatment time is 30 seconds or less, the change in the light distribution of the diffuse reflected light is small, and there is almost no anti-glare effect. Further, even if the satin processing time is 90 seconds or longer, there is almost no change in the light distribution of diffuse reflected light, and the antiglare effect does not increase beyond this time. From the viewpoint of the antiglare function, it can be said that the satin treatment time is preferably more than 30 seconds and less than 90 seconds.

The light distribution of the diffusely reflected light of the sample film with a satin processing time in the range of 37 seconds to 75 seconds is that the slope of the light distribution curve changes discontinuously, and the light reception angle is 0 ° to 10 °. The relative diffuse reflectance (%) is in the range of 1% or more and 10% or less. Specifically, the slopes of the light distribution curves of these sample films change discontinuously when the light receiving angle is about 2 ° to about 3 ° and about 7 ° to about 8 ° (the absolute value of the slope is Discontinuously smaller). These sample films were found to have an appropriate anti-glare function (having a haze value of about 7 or more and about 24 or less) and moderate specular reflectivity.

Referring to FIG. 10B, the results of evaluating the antiglare function and the specular reflectivity will be described. FIG. 10B shows a result obtained by simple model calculation of a state in which the black and white pattern indicated by ORG is observed through each sample film based on the measurement result of the light distribution of diffuse reflection light described above. . That is, this corresponds to obtaining the light distribution of diffuse reflected light in the state where the above-described black and white pattern is arranged at the position of the glass plate in FIG.

CNV. 1 is a result calculated using the light distribution of diffuse reflected light shown in FIG. 8A, and E30, E45, E60, and E90 are the light distribution of diffuse reflected light shown in FIG. 10A, respectively. The number is the result of calculation using, and the number indicates the satin processing time.

Each area of the black and white pattern indicated by ORG in FIG. 10B is composed of 233 cells (corresponding to pixels). The intensity of light reaching the observer's eyes when each cell was observed was determined as follows.

For example, consider the nth cell. The intensity of light reaching the observer's eye when observing the nth cell is equal to the intensity of light exiting the nth cell, relative diffuse reflectance (%) at 0.0 ° of the light distribution curve. Multiplied by a value obtained by multiplying the intensity of the light emitted from the (n−1) th and (n + 1) th cells by the relative diffuse reflectance (%) at 0.1 ° of the light distribution curve, and The intensity of the light emitted from the (n−2) th and (n + 2) th cells is added to a value obtained by multiplying the light distribution distribution curve by the relative diffuse reflectance (%) at 0.2 °, so that It calculated | required as a value which added the intensity | strength of the light radiate | emitted from 50 cells of both sides.

CNV. As can be seen by looking at 1, the boundary line between black and white is blurred and cannot be clearly recognized. Thus, CNV. Although the antireflection film with diffuse reflection function 1 has a small haze value of 3, the specular reflectivity is low and the image is blurred.

On the other hand, for the E45 to E60 sample films (anti-glare film) in FIG. 10B, the boundary line between black and white can be clearly recognized. In terms of the anti-glare function, the width of the gray area that has entered the black area is CNV. It is larger than 1, and it can be said that the antiglare function is high.

In the E30 sample film, the specular reflectivity is too high, so that the boundary line between black and white is clearly recognized. Further, in the E90 sample film, the specular reflectivity is too low, so that the boundary line between black and white cannot be clearly recognized. This corresponds well with the result of subjective evaluation by visual observation, and in order to obtain an antireflection film (antireflection surface) having an appropriate antiglare function and appropriate specular reflectivity, the above-mentioned satin treatment time is used. It is preferably 30 seconds or more and 75 seconds or less.

Therefore, the sample film having a satin processing time in the range of more than 30 seconds and less than 90 seconds has an appropriate anti-glare function and an appropriate specular reflectivity. For example, even when used for a high-definition display exceeding 300 ppi, The image is prevented from blurring more than necessary.

It should be noted that the preferable time for the satin treatment can be optimized as appropriate depending on the concentration and temperature of the treatment liquid. For example, when an aqueous solution containing 5 mass% of ammonium fluoride is used as an aqueous solution containing hydrogen fluoride and ammonium, the aqueous solution containing 4 mass% of the above-mentioned ammonium hydrogen fluoride is treated at 25 ° C. for 120 seconds. A result equivalent to the example using the above (processing time 45 to 60 seconds) can be obtained.

If the matte processing time is short, there is a possibility of causing a problem in the mass production stability. Therefore, it is preferable to improve the mass production stability (controllability) within a range in which the throughput is not lowered more than necessary. Therefore, it was examined to increase the time of the satin treatment by lowering the temperature of the satin treatment.

Referring to FIG. 11, the relationship between the satin treatment time and the light distribution of diffuse reflected light when the satin treatment is performed at 10 ° C. using an aqueous solution containing ammonium hydrogen fluoride having a concentration of 4 mass% will be described.

As can be seen from FIG. 11, the light distribution of the diffuse reflected light of the sample film in the processing time range of 2 minutes 30 seconds to 8 minutes is REF_No. 1-No. 4 is within the range of the light distribution of diffuse reflected light, and has an anti-glare performance that almost covers the anti-glare performance of various anti-glare films currently in use by extending the processing time even if the processing temperature is lowered. It was found that a surface (antiglare structure) can be formed. That is, by reducing the processing temperature from 35 ° C. to 10 ° C., the appropriate processing time can be expanded from the range of more than 30 seconds to less than 90 seconds to the range of 2 minutes 30 seconds to 8 minutes. By lowering the treatment temperature in this way, there is an advantage that it is possible to increase the margin of the matte treatment time.

In addition, when the concentration of the ammonium hydrogen fluoride aqueous solution is lower than 4 mass%, crystal grains become conspicuous and an appropriate antiglare function may not be imparted. Therefore, the concentration of the ammonium hydrogen fluoride aqueous solution used for the satin treatment is preferably 4 mass% or more.

The upper limit of the concentration of the ammonium hydrogen fluoride aqueous solution is not particularly limited, but if it exceeds 19 mass%, there is a possibility that a surface having an appropriate diffuse reflection may not be formed. Therefore, the concentration of the ammonium hydrogen fluoride aqueous solution is preferably 19 mass% or less. .

[Suppressing the effects of cutting marks on aluminum substrates]
When a satin treatment is applied to an aluminum base material that has been mirror-finished by cutting with a bit without performing cold drawing, cutting traces may be formed on the surface of the aluminum base material. This cutting trace is considered to be etching unevenness caused by a work-affected layer formed on the surface of the aluminum base material by mirror finishing by cutting with a cutting tool. Therefore, the problem that the cutting trace is formed by the satin treatment is not limited to the cutting by the bite, and is a common problem when using an aluminum base material that has been subjected to mirror finishing accompanied by formation of a work-affected layer. If cold drawing is performed, a work-affected layer due to plastic deformation is formed over the entire aluminum base, so that it is considered that the influence of subsequent mirror finishing is reduced.

As a result of various investigations, it was found that cutting marks can be reduced by performing an anodizing step and an etching step for pretreatment before a satin treatment with an aqueous solution containing a salt of hydrogen fluoride and ammonium. . That is, by removing the formed anodic oxide film by etching by anodizing the mirror-finished surface by cutting by cutting, cutting traces formed on the surface of the aluminum substrate can be reduced.

In the anodic oxidation, an aqueous sulfuric acid solution is preferably used as the electrolytic solution. When a sulfuric acid aqueous solution is used, a softer anodic oxide film can be obtained than when oxalic acid is used, and therefore, it can be easily removed by using, for example, a phosphoric acid aqueous solution. Anodization using an aqueous sulfuric acid solution is preferably performed at 20 ° C. and a constant current of 115 A / m ² for 24 minutes and 30 seconds, for example. If the anodic oxidation time is shorter than this, cutting traces may be formed.

The results of an experimental example performed using a mold base material manufactured using an aluminum base material (JIS A6063) that has been mirror-finished by bite cutting without cold drawing is shown below.

FIG. 12A shows anodization (80 V, 5 ° C., 10 minutes) using an oxalic acid aqueous solution (concentration: 0.3 mass%), and then etching (30 ° C., using a phosphoric acid aqueous solution (concentration: 10 mass%)). FIG. 12B is a diagram showing an SEM image (5,000 times, full scale 10 μm in the SEM image) of the aluminum substrate after 90 minutes), and FIG. 12B is anodized using an aqueous sulfuric acid solution (concentration: 17 mass%). (Constant current 115 A / m ² , 20 ° C., 24 minutes 30 seconds), and then etching (30 ° C., 12 minutes) using an aqueous phosphoric acid solution (concentration: 10 mass%) (SEM image of the surface of the aluminum substrate ( It is a figure which shows 5000 times, full scale 10micrometer in a SEM image.

As can be seen from FIG. 12 (a), a large number of recesses are formed on the surface of the aluminum base anodized with oxalic acid. This is because the oxide film formed by anodic oxidation using oxalic acid is hard and difficult to etch, so that the etching proceeds slowly with a portion of the oxide film remaining. At this time, it is considered that galvanic corrosion progressed on the surface from which the oxide film was removed, and as a result, a large number of recesses were formed. Galvanic corrosion occurs between Ti and Al contained in the aluminum film.

On the other hand, as can be seen from FIG. 12 (b), no concave portion formed by galvanic corrosion is seen on the surface of the aluminum base anodized with sulfuric acid. This is probably because the oxide film formed by anodic oxidation using sulfuric acid was soft and was easily removed by etching. As illustrated here, when anodization is performed using sulfuric acid, the anodized film can be removed only by performing etching for 12 minutes thereafter.

The etching time required for removing the oxide film formed by anodic oxidation using sulfuric acid was examined. The conditions for anodization are the same as the above conditions (constant current 115 A / m ² , 20 ° C., 24 minutes 30 seconds), and using phosphoric acid aqueous solution (concentration: 0.3 mass%), the etching time is 30 ° C. It was changed to 1 minute, 3 minutes, 5 minutes, 10 minutes, and 12 minutes, and the presence or absence of the oxide film was examined. As a result, it was found that the oxide film can be removed by etching for 5 minutes or more. Examples of experimental results are shown below.

FIGS. 13A to 13D show SEM images (10,000 times, full scale 200 nm in the SEM image) of the surfaces of the samples having different etching times with phosphoric acid after anodizing with sulfuric acid under the above conditions. Show. 13 (a) shows an etching time of 12 minutes, FIG. 13 (b) shows an etching time of 10 minutes, FIG. 13 (c) shows an etching time of 5 minutes, and FIG. 13 (d) shows an etching time of 3 minutes. It is a SEM image. Except for the sample having an etching time of 3 minutes (see FIG. 13D), the oxide film is removed. However, the etching time is preferably set to 10 minutes or more because unevenness may be visually confirmed in the etching for 5 minutes.

The time for the satin treatment to be performed after the anodization and etching as the above-mentioned pretreatment were examined on an aluminum base material (JIS A6063) that had been mirror-finished by cutting with a bit without performing cold drawing. This is because the state of the surface of the aluminum base material varies depending on the presence or absence of the pretreatment, so that it is possible that the preferred satin treatment time may be different.

After anodizing and etching as described above, a satin treatment was performed with an aqueous solution containing ammonium hydrogen fluoride (concentration: 4 mass%, temperature: 20 ° C.) at treatment times of 30 seconds, 60 seconds, and 120 seconds. . A sample film is prepared using the obtained mold substrate, and the result of evaluating the light distribution characteristics by the same method as described above with reference to FIG. 8B is shown in FIG. Similarly to FIG. 8A, FIG. 14 also shows the relative diffuse reflectance (%) normalized by setting the incident angle to 5 °, the light receiving angle to the horizontal axis, and the maximum value of diffuse reflected light intensity to 80%. The light distribution curve is shown with the common logarithm on the vertical axis.

As can be seen from FIG. 14, the light distribution of the sample film with a satin treatment time of 30 seconds is REF_No. It is narrower than 1, and does not have a sufficient anti-glare function. The light distribution of the sample with a satin treatment time of 60 seconds and 120 seconds has a point where the slope of the light distribution curve changes discontinuously within the range of the light receiving angle of 0 ° to 10 °, and The relative diffuse reflectance (%) is in the range of 1% to 10%.

Therefore, the satin treatment performed after performing the above-described anodization and etching as the above-mentioned pre-treatment on a mold base produced using an aluminum base material that has been mirror-finished by cutting without performing cold drawing This time is preferably 60 seconds or more when an aqueous solution containing ammonium hydrogen fluoride (concentration: 4 mass%, temperature: 20 ° C.) is used.

FIG. 15 (a) shows a SEM image of the surface of the aluminum base material that has been subjected to cold drawing and then mirror-finished by cutting with a bite for 37 seconds (see FIG. 10A). ), After anodizing and etching as a pretreatment on an aluminum base material that has been mirror-finished by bite cutting without performing cold drawing on the aluminum base material produced by the boat hole method, The SEM image of the surface which performed the satin processing for a second (refer FIG. 14) is shown. Each SEM image is 10,000 times, and the full scale in the SEM image is 5 μm.

As can be seen from FIGS. 15 (a) and 15 (b), 2 when viewed from the normal direction of the surface of the macro convex portion (see macro convex portion 18p in FIG. 1 (c)) formed by the satin treatment. It can be seen that the dimensional size (area circle equivalent diameter) is about 1 μm or more and 5 μm or less. The average of the two-dimensional size of the macro convex portions is slightly smaller than the average distance between adjacent macro concave portions (AD _int , see FIG. 1B).

Using these aluminum substrates, moth-eye molds were prepared in the same manner as described above, and sample films were prepared in the same manner as described above with reference to FIG. Observation of the obtained antireflection film having an antiglare function on a liquid crystal display panel (diagonal 4.97 inches, dot pitch (Px in FIG. 16) is 19.1 μm, pixel pitch is about 57.3 μm, about 440 ppi) When it was pasted on the surface of the user and visually evaluated, it was found that glare on the display surface was suppressed and blurring of the image was suppressed.

[Step of etching surface of aluminum substrate]
As a pretreatment for the satin treatment, a result of studying a step of etching the surface of the aluminum substrate using an alkaline etching solution (sometimes referred to as a substrate surface etching step) will be described.

When a satin finish was applied to an aluminum base material that had been mirror-finished by cutting, cutting marks were sometimes formed on the surface of the aluminum base material. This cutting trace is considered to be etching unevenness caused by a work-affected layer formed on the surface of the aluminum base material by mirror finishing by cutting with a cutting tool. Further, when an antireflection film formed using a mold having cutting marks is pasted on a liquid crystal display panel, moire may occur. In this moire, the stripes of the cutting marks transferred to the antireflection film interfere with the dot structure (Px in FIG. 16) or the periodic structure (for example, pixel array) arranged at the pixel pitch of the liquid crystal display panel. This is thought to be caused by

As a result of various investigations, cutting marks can be reduced by etching the surface of the aluminum base material using an alkaline etching solution before the satin treatment with an aqueous solution containing a salt of hydrogen fluoride and ammonium. I understood.

As shown in Table 2 below, the substrate surface etching process was performed under different conditions before the satin treatment. Experimental Examples 1 to 7 were performed using a mold base material produced using an aluminum base material (JIS A6063) that was subjected to cold drawing and then mirror-finished by cutting with a bite.

The alkaline etching solution E1 used in Experimental Example 1 is an aqueous solution having an organic alkaline cleaning agent (LC-2 manufactured by Yokohama Oil & Fat Co., Ltd.) having a concentration of 8 mass%. LC-2 manufactured by Yokohama Oil & Fat Co., Ltd. has the following composition: 2-aminoethanol (12 mass%), chelating agent (2 mass% to 6 mass%), and surfactant (2 mass% to 6 mass%). Therefore, the concentration of 2-aminoethanol in the alkaline etching solution E1 is 0.96 mass%. The pH of the alkaline etching solution E1 is 10.3.

The pH of each alkaline etching solution was measured using a handy pH meter (product name: D-25, manufactured by HORIBA). By including the chelating agent in the alkaline etching solution, it is possible to prevent other metals and impurities contained in the aluminum base material, which are dissolved by etching, from adhering to the surface of the aluminum base material. When the alkaline etching solution contains a surfactant, the substrate surface can be etched more uniformly.

The alkaline etching solution E3 used in Experimental Example 3 is an aqueous solution having a concentration of 3% by mass of an inorganic alkaline detergent (LG, manufactured by Yokohama Oil & Fat Co., Ltd.). Manufactured by Yokohama Oil & Fat Co., Ltd. G. L includes the following composition: potassium hydroxide (1 mass% to 3 mass%), chelating agent (5 mass% to 15 mass%), surfactant (5 mass% to 15 mass%). Therefore, the concentration of potassium hydroxide in the alkaline etching solution E3 is 0.03 mass% to 0.09 mass%. The pH of the alkaline etching solution E3 is 11.7.

The alkaline etching solution E2 used in Experimental Example 2 was left for a month or more in a state where the alkaline etching solution E3 was exposed to air. The alkaline etching solution E2 has weaker alkalinity than the alkaline etching solution E3. The pH of the alkaline etching solution E2 is 9.92.

In Experimental Examples 1 to 3, after immersing the sample in each alkaline etching solution (40 ° C.) for a predetermined time, the sample was washed with water by immersing in pure water. After washing with water, the satin treatment was performed without drying completely. For the satin treatment, an aqueous solution containing ammonium hydrogen fluoride (concentration: 4 mass%, temperature: 10 ° C.) was used, and the treatment time was 5 minutes.

In Experimental Examples 4 to 6, no satin treatment is performed after the substrate surface etching step. In Experimental Examples 4 to 6, the substrate surface etching process was performed using the same alkaline etching solutions E1 to E3 used in Experimental Examples 1 to 3.

The alkaline etching solution E4 used in Experimental Example 7 is an aqueous solution having a concentration of 0.10 mass% of an inorganic alkaline detergent (LG, manufactured by Yokohama Oil & Fat Co., Ltd.). Therefore, the concentration of potassium hydroxide in the alkaline etching solution E4 is 0.001 mass% to 0.003 mass%. The alkaline etching solution E4 is prepared using the same inorganic alkaline cleaning agent as the alkaline etching solution E3, but differs in its concentration. The pH of the alkaline etching solution E4 is 10.38. In Experimental Example 7, as in Experimental Examples 1 to 3, a satin treatment was performed after the substrate surface etching step.

For Experimental Examples 1 to 7, an anti-glare film was formed using, as a mold, an aluminum base material that had been subjected to the base material surface etching step and the matte finish (or base material surface etching step). The anti-glare film is formed by applying a release agent (Optool DSX manufactured by Daikin Industries, Ltd.) to the surface of the aluminum base material, then applying an acrylic UV curable resin, and irradiating the UV light in a state of being transferred onto the TAC film. And then cured.

Table 3 shows the results of evaluating the antiglare function using an aluminum base material and an antiglare film (sample film) obtained from the aluminum base material.

In Table 3, “Ra”, “unevenness” and “pattern” are the results of evaluation of the aluminum base material, and “haze value”, “moire”, “antiglare” and “white brown” are antiglare films. It is the result of evaluating. “Haze value” and “Ra” are measurement results, and “moire”, “unevenness”, “pattern”, “antiglare” and “white-brown” are subjective evaluations by visual observation. Each will be described below.

“Ra” in Table 3 indicates the result of measuring the arithmetic average roughness Ra of the surface of the aluminum substrate. The arithmetic average roughness Ra was measured using an optical profiling system (Wyko NT1100) manufactured by Veeco. It is preferable that the arithmetic average roughness Ra of the surface of the aluminum substrate is, for example, 50 nm or more and 300 nm or less by the substrate surface etching step and the satin treatment.

“Unevenness” in Table 3 is a result of visual evaluation on whether or not unevenness occurs on the surface of the aluminum base material. It was evaluated whether or not the satin finish on the surface of the aluminum substrate was performed uniformly. Regarding “unevenness” in Table 3, “◯” indicates that there is no unevenness, and “x” indicates that there is unevenness. In Experimental Example 7, it is considered that the work-affected layer could not be sufficiently removed because the concentration of the base contained in the alkaline etching solution used in the substrate surface etching step was low. As will be described later, when unevenness did not occur (when the satin treatment was performed uniformly), for example, about 1.4 μm was removed from the surface of the aluminum base material. In Experimental Example 7, it is considered that the satin finish was not uniformly performed due to the small thickness of the aluminum base material etched in the base material surface etching step, and unevenness occurred.

Also, the following may be considered as the reason why the unevenness occurred in Experimental Example 7. The alkaline etching solution E4 used in Experimental Example 7 is prepared using the same inorganic alkaline cleaning agent as the alkaline etching solution E3 used in Experimental Example 3, but differs in that the concentration is low. Therefore, in Experimental Example 7, it is considered that the concentration of the base contained in the alkaline etching solution is lower than that of Experimental Example 3, and the action of etching the surface of the aluminum substrate is weak. In Experimental Example 7, the concentration of the chelating agent contained in the alkaline etching solution is also low, but depending on the amount of other metals and impurities contained in the aluminum substrate, the function of adsorbing and sequestering these ions is Compared with the case of Experimental Example 3, it may not decrease much. In such a case, it is considered that the non-uniformity of the etching of the surface of the aluminum substrate by the alkaline etching solution can be increased by the function of the chelating agent. This leads to an increase in the non-uniformity of the satin treatment, and as a result, unevenness may have occurred.

The concentration of the base contained in the alkaline etching solution is preferably 0.01% by mass or more, for example. The concentration of the inorganic base contained in the alkaline etching solution is preferably 0.03 mass% or more, for example. The concentration of the organic base contained in the alkaline etching solution is preferably 0.96 mass% or more, for example.

The “pattern” in Table 3 is a result of visual evaluation of whether or not a pattern is formed on the surface of the aluminum base material. Here, the pattern refers to a concavo-convex shape that is several hundred to several thousand times larger than the antiglare structure, for example. Regarding “pattern” in Table 3, “◯” indicates that a pattern is not generated, and “×” indicates that a pattern is generated. On the surface of the aluminum base material of Experimental Example 6, an uneven shape of the order of about 1 mm was generated. Due to the pattern (uneven shape) on the surface of the aluminum substrate, the pattern was conspicuous even when the antiglare film was attached to the surface of the black acrylic plate. Since this pattern is several hundred to several thousand times larger than the antiglare structure, it does not have an antiglare function.

This surface pattern (uneven shape) of the aluminum substrate is considered to have occurred because, for example, the pH of the alkaline etching solution E3 used in Experimental Example 6 is 11.7 and the alkalinity is strong. It is considered that the surface of the aluminum substrate was roughened more than necessary by the strong alkaline base, and the pattern was generated. In the substrate surface etching step, the possibility of a concentration gradient in the alkaline etchant can also be considered as one of the causes of the pattern. Moreover, it is thought that the pattern of the surface of an aluminum base material originates in the process deterioration layer formed in the surface of the aluminum base material by the mirror surface process by a bite cutting, for example. For example, if the aluminum base material has non-uniform composition, it may be one of the causes of pattern generation.

No pattern was formed on the surface of the aluminum base material of Experimental Example 3. By the satin treatment using the aqueous solution containing ammonium hydrogen fluoride after the substrate surface etching step, the work-affected layer on the surface of the aluminum substrate was partially removed and / or the surface pattern of the aluminum substrate was It is thought that it became inconspicuous.

“Haze value” in Table 3 indicates the result of measuring the haze value of the antiglare film. The haze value was obtained from (diffuse transmittance / total light transmittance) × 100 using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

“Moire” in Table 3 is a result of visual evaluation of whether or not moire occurs by attaching an antiglare film to the surface of a display panel of a liquid crystal television (AQUAS UD1, manufactured by Sharp Corporation). Regarding “moire” in Table 3, “◯” indicates that moire has not occurred, and “x” indicates that moire has occurred.

“Anti-glare property” in Table 3 is a result of judging the presence or absence of anti-glare property by attaching an anti-glare film to the surface of a black acrylic plate and visually observing the reflection of a fluorescent lamp. Regarding “Anti-Glare” in Table 3, “◯” indicates that it is determined that there is anti-glare, and “X” indicates that it is determined that there is no anti-glare. In general, an antiglare film having a large haze value is excellent in antiglare function and antiglare property.

“White-brown” in Table 3 has an anti-glare film attached to the surface of the display panel of a liquid crystal television (AQUOS UD1, manufactured by Sharp Corporation). It is a result. Interviews were conducted with 5 people, and “○” in Table 3 indicates that 0 out of 5 people answered “I ’m worried about white tea”. It indicates that there are 3 or more people and “x” indicates that there are 4 or more people. In general, an antiglare film having a large haze value is likely to appear whitish due to its antiglare function.

Of the above, the evaluation of “anti-glare” and “white-brown” may vary depending on the degree of anti-glare function that the evaluator wants to realize. For example, the evaluation in Table 3 above is a case where a haze value of about 7 or more and about 24 or less is set as an appropriate antiglare function. The mold manufactured by the mold manufacturing method according to the embodiment of the present invention is not limited to the example, and an antireflection film having a higher antiglare function (having a larger haze value (for example, about 7 or more and about 28 or less)) is provided. It can also be used to form. Of course, it can be used to form an antireflection film having a lower antiglare function (having a smaller haze value (for example, about 1 to about 5)).

In the substrate surface etching step, for example, about 1.4 μm was removed from the surface of the aluminum substrate. The thickness etched in the substrate surface etching step can be appropriately adjusted by adjusting the etching time, the temperature of the etching solution, and the like. The thickness that is preferably etched in the substrate surface etching step varies depending on, for example, the state of the surface of the aluminum substrate. The thickness to be etched is not limited to the above example, and it is preferable to perform the etching so that the work-affected layer on the surface of the aluminum base material is sufficiently removed.

From the above experimental example, in order to obtain an antireflection film having an appropriate antiglare function (for example, a haze value of about 7 or more and about 24 or less), the pH of the alkaline etching solution used in the substrate surface etching step is, for example, 10 It is preferably 12 or less. When the pH of the alkaline etching solution is 9 or less, there is a possibility that the work-affected layer on the surface of the aluminum substrate cannot be sufficiently removed. When the pH of the alkaline etching solution is 13 or more, there is a possibility that the surface of the aluminum substrate is roughened more than necessary and / or may cause unevenness.

However, the preferable range of the pH of the alkaline etching solution used in the substrate surface etching step may vary depending on the surface state of the aluminum substrate. The surface state of the aluminum substrate may vary depending on, for example, the type of aluminum substrate, the production method, and / or the processing method.

[Pear finish with alkaline etching solution]
The results of studying that the satin treatment is performed with an alkaline etching solution instead of an aqueous solution containing a salt of hydrogen fluoride and ammonium will be described.

It has been found that cutting marks can be reduced by performing a satin treatment with an alkaline etching solution instead of an aqueous solution containing a salt of hydrogen fluoride and ammonium. This is considered to be because the surface of the aluminum base material is etched simultaneously with the satin treatment with the alkaline etching solution, and the work-affected layer formed on the surface of the aluminum base material is removed.

As shown in Table 4 below, the matte treatment with an alkaline etching solution was performed under different conditions. In Experimental Examples 8 to 15, a mold base material manufactured using an aluminum base material (JIS A6063) that was mirror-finished by bite cutting without subjecting the aluminum base material manufactured by the mandrel method to cold drawing. Used.

In Experimental Examples 8, 9, and 11, the satin treatment was performed by immersing the sample in an alkaline etching solution E1 (the same as that used in Experimental Example 1) for a predetermined time.

In Experimental Example 10, a satin finish treatment was performed by immersing the sample in an alkaline etching solution E2 (same as that used in Experimental Example 2) for a predetermined time.

The alkaline etching solution E5 used in Experimental Example 12 is the alkaline etching solution E1 left for more than one month in contact with air. The alkaline etching solution E5 has weaker alkalinity than the alkaline etching solution E1. The pH of the alkaline etching solution E5 is 9.20.

In Experimental Examples 13 and 14, a satin treatment was performed by immersing the sample in an alkaline etching solution E3 (same as that used in Experimental Example 3) for a predetermined time.

In Experimental Example 15, a satin finish treatment was performed by immersing the sample in an alkaline etching solution E4 (same as that used in Experimental Example 7) for a predetermined time.

In Experimental Examples 8 to 15, after immersing the sample in each alkaline etching solution (40 ° C.) for a predetermined time, the sample was washed with water by immersing in pure water. After washing with water, the sample was dried.

For Experimental Examples 8 to 15, an anti-glare film was formed using an aluminum base material subjected to a matte treatment with an alkaline etching solution as a mold. The anti-glare film is formed by applying a release agent (Optool DSX manufactured by Daikin Industries, Ltd.) to the surface of the aluminum base material, then applying an acrylic UV curable resin, and irradiating the UV light in a state of being transferred onto the TAC film. And then cured.

Table 5 shows the results of evaluating the antiglare function using an aluminum base material and an antiglare film (sample film) obtained from the aluminum base material. The evaluation method and the notation in Table 5 are the same as those described for Table 3 above.

In Experimental Example 11, moire occurred. Compared with Experimental Example 8 and Experimental Example 9 in which moire did not occur, in Experimental Example 11, the time during which the sample was immersed in the alkaline etching solution E1 was shorter. In Experimental Example 11, it is considered that the moire was caused by insufficient etching of the work-affected layer on the surface of the aluminum substrate.

In Experiment Example 12 and Experiment Example 15, unevenness occurred. In Experimental Example 12, the pH of the alkaline etching solution E5 used was 9.20, and it was considered that the work-affected layer could not be sufficiently removed because the alkalinity was weak. In Experimental Example 15, it is considered that the work-affected layer could not be sufficiently removed because the concentration of the base contained in the alkaline etching solution E4 was low. As will be described later, when unevenness did not occur (when the satin treatment was performed uniformly), for example, about 1.4 μm was removed from the surface of the aluminum base material. In Experimental Example 12 and Experimental Example 15, it is considered that the satin treatment was not performed uniformly due to the small thickness of the aluminum base material etched in the base material surface etching step, and unevenness occurred.

Further, as the reason why the unevenness occurred in the experimental example 15, as described above with respect to the experimental example 7, it may be due to the function of the chelating agent. This will be described below.

The alkaline etching solution E4 used in Experimental Example 15 has a low concentration of base contained in the alkaline etching solution. The pH of the alkaline etching solution E5 used in Experimental Example 12 is 9.20, and the alkalinity is weak. Therefore, in Experimental Example 12 and Experimental Example 15, it is considered that the action of etching the surface of the aluminum substrate is weak. However, in Experimental Example 12 and Experimental Example 15, depending on the amount of other metals and impurities contained in the aluminum base material, the chelating agent contained in the alkaline etching solution has little function to adsorb and sequester these ions. It may not be low. In such a case, it is considered that the non-uniformity of the etching of the surface of the aluminum substrate by the alkaline etching solution can be increased by the function of the chelating agent. This leads to an increase in the non-uniformity of the satin treatment, and as a result, unevenness may have occurred.

The concentration of the base contained in the alkaline etching solution is preferably 0.01% by mass or more, for example. The concentration of the inorganic base or organic base contained in the alkaline etching solution is preferably 0.03 mass% or more, for example. The concentration of the organic base contained in the alkaline etching solution is preferably 0.96 mass% or more, for example.

In Experiment 13 and Experiment 14, a pattern occurred. In Experimental Example 13 and Experimental Example 14, since the pH of the alkaline etching solution E3 used was relatively high, it is considered that the surface of the aluminum substrate was roughed more than necessary by the strong alkaline base. As a result, it is considered that a pattern was generated. In addition, as described above with respect to Table 3, the pattern generated on the surface of the aluminum base material is considered to be caused by a work-affected layer formed on the surface of the aluminum base material by, for example, mirror finishing by cutting with a bite. .

From the above experimental example, it is preferable that the arithmetic average roughness Ra of the surface of the aluminum substrate is, for example, 50 nm or more and 200 nm or less by the satin treatment with an alkaline etching solution.

For example, about 1.4 μm was removed from the surface of the aluminum substrate in the matte treatment process using an alkaline etching solution. The thickness to be etched can be appropriately adjusted, for example, by adjusting the etching time, the temperature of the etching solution, and the like. The thickness that is preferably etched depends on, for example, the state of the surface of the aluminum substrate. The thickness to be etched is not limited to the above example, and it is preferable to perform the etching so that the work-affected layer on the surface of the aluminum base material is sufficiently removed.

The matte treatment process using an alkaline etching solution is performed by bringing the surface of the aluminum base material into contact with the alkaline etching solution for 45 minutes or more, for example. Thereby, the satin treatment process by alkaline etching liquid can serve as a degreasing process.

From the above experimental example, in order to obtain an antireflection film having an appropriate antiglare function (for example, a haze value of about 7 or more and about 24 or less), the pH of the alkaline etching solution used for the satin treatment is, for example, 9.5 or more. It can be seen that 11 or less is preferable. When the pH of the alkaline etching solution is 9 or less, there is a possibility that the work-affected layer on the surface of the aluminum substrate cannot be sufficiently removed. When the pH of the alkaline etching solution is 12 or more, the surface of the aluminum substrate may be roughened more than necessary, and / or the satin treatment may not be performed uniformly.

However, the preferable range of the pH of the alkaline etching solution used for the satin treatment may vary depending on the surface state of the aluminum substrate. The surface state of the aluminum substrate may vary depending on, for example, the type of aluminum substrate, the production method, and / or the processing method.

In addition, the mold manufactured by the mold manufacturing method according to the embodiment of the present invention is not limited to the illustrated example, and has a higher antiglare function (having a larger haze value (for example, about 7 or more and about 28 or less)) antireflection. It can also be used to form films. Of course, it can be used to form an antireflection film having a lower antiglare function (having a smaller haze value (for example, about 1 to about 5)).

As described above, the moth-eye that can provide an antireflection function and an antiglare function can be obtained by forming the inverted moth-eye structure using the thus-obtained cylindrical aluminum substrate subjected to the satin treatment. A mold is obtained. When a cylindrical moth-eye mold is used, the antireflection film can be formed by the roll-to-roll method as described above. At this time, in order to improve the adhesion between the film base material (TAC film or PET film) on which the antireflection film is formed and the antireflection film, it is preferable to undergo the following steps.

A UV curable resin containing a solvent (for example, acrylic resin) is applied on the TAC film (thickness is, for example, 2 μm to 20 μm). At this time, as the solvent, a solvent that dissolves the surface of the TAC film (for example, a ketone) is selected. When the solvent dissolves the surface of the TAC film, a region where TAC and the ultraviolet curable resin are mixed is formed.

Thereafter, the solvent is removed, and the TAC film is wound so that the ultraviolet curable resin is in close contact with the outer peripheral surface of the moth-eye mold.

Subsequently, ultraviolet rays are irradiated to cure the ultraviolet curable resin. At this time, the temperature of the ultraviolet curable resin is maintained at 30 ° C. to 70 ° C.

Thereafter, the TAC film is peeled off from the moth-eye mold, and again irradiated with ultraviolet rays as necessary.

When the hard coat layer is formed on the TAC film, the material for forming the hard coat layer may contain a solvent that dissolves the surface of the TAC film. In this case, it is not necessary to add a solvent to the ultraviolet curable resin for forming the antireflection film.

In the case of using a PET film, it is preferable to form a layer (2 μm to 20 μm in thickness) of an aqueous primer (for example, a polyester resin or an acrylic resin) before applying the ultraviolet curable resin. Also in this case, it is not necessary to add a solvent to the ultraviolet curable resin for forming the antireflection film.

The mold manufacturing method according to the present invention is used for manufacturing a mold suitably used for forming an antireflection film (antireflection surface) or the like. The antireflection film according to the present invention has a surface structure that exhibits an appropriate antiglare function and an excellent antireflection function, and is suitably used for, for example, a high-definition display panel.

DESCRIPTION OF SYMBOLS 10 Type | mold base material 12 Aluminum base material 14 Porous alumina layer 14p Micro recessed part 16 Inorganic material layer 18 Aluminum film | membrane 18r Aluminum residual layer 100 Moss eye type | mold

Claims

(A) preparing a cylindrical aluminum base material formed of an Al—Mg—Si based aluminum alloy and mechanically mirror-finished;
(B) a step of treating the surface of the aluminum substrate with an alkaline etchant;
(C) after the step (b), forming an inorganic material layer on the surface of the aluminum substrate, and forming an aluminum film on the inorganic material layer, thereby producing a mold substrate; ,
(D) after the step (c), anodizing the surface of the aluminum film to form a porous alumina layer having a plurality of micro-recesses;
(E) after the step (d), by enlarging the plurality of micro concave portions of the porous alumina layer by bringing the porous alumina layer into contact with an etching solution;
(F) After the said process (e), it further anodizes, The process of growing these several micro recessed part is included, The manufacturing method of a type | mold.
The method for producing a mold according to claim 1, wherein the arithmetic average roughness Ra of the surface of the aluminum base material is 50 nm or more and 200 nm or less by the step (b).
The method for producing a mold according to claim 1 or 2, wherein the alkaline etching solution contains 0.03 mass% or more of an inorganic base or an organic base.
The method for producing a mold according to any one of claims 1 to 3, wherein the pH of the alkaline etching solution is 9.5 or more and 11 or less.
The method for producing a mold according to any one of claims 1 to 4, wherein the alkaline etching solution contains an organic compound having an amino group.
The method for producing a mold according to any one of claims 1 to 5, wherein the alkaline etching solution contains potassium hydroxide.
The method for manufacturing a mold according to any one of claims 1 to 6, wherein in the step (b), at least 1.4 µm is removed from the surface of the aluminum base material.
The method for manufacturing a mold according to any one of claims 1 to 7, wherein the step (b) is performed by bringing the surface of the aluminum base material into contact with the alkaline etching solution for 45 minutes or more.
The method for manufacturing a mold according to any one of claims 1 to 8, wherein the step (b) also serves as a degreasing step.
The method for producing a mold according to any one of claims 1 to 9, wherein the aluminum substrate is an aluminum substrate formed by a mandrel method.
A mold manufactured by the mold manufacturing method according to claim 1.
A plurality of macroscopic protrusions having a two-dimensional size of 200 nm to 30 μm when viewed from the surface normal direction and a two-dimensional size of 10 nm to 500 nm when viewed from the surface normal direction A mold having a porous alumina layer with a surface structure, having a plurality of microscopic recesses less than.
Preparing a mold according to claim 11 or 12,
A step of preparing a workpiece;
Curing the photocurable resin by irradiating the photocurable resin with light in a state in which the photocurable resin is applied between the mold and the surface of the workpiece;
A method for producing an antireflection film, comprising a step of peeling the antimolding film formed of a cured photocurable resin.
An antireflection film produced by the method for producing an antireflection film according to claim 13.
The antireflection film according to claim 14, wherein the haze value is from about 7 to about 24.