JP6626898B2 - Substrate surface treatment method and mold manufacturing method - Google Patents

Description

  The present invention relates to a method for surface treatment of a substrate and a method for manufacturing a mold. The "mold" used herein includes molds used for various processing methods (stamping and casting), and may be referred to as a stamper. It can also be used for printing (including nanoprints).

  2. Description of the Related Art Optical devices such as display devices and camera lenses used in televisions and mobile phones are generally provided with an anti-reflection technique in order to reduce surface reflection and increase the amount of transmitted light. For example, when light passes through an interface between media having different refractive indices, such as when light enters the interface between air and glass, the amount of light transmission decreases due to Fresnel reflection and the like, and visibility deteriorates. 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 unevenness is controlled to be equal to or less 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 projections forming the concave / convex pattern exhibiting the antireflection function is 10 nm or more and less than 500 nm. Here, the “two-dimensional size” of the projection refers to the area circle equivalent diameter of the projection when viewed from the surface normal direction. For example, when the projection is conical, 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 is based on the principle of a so-called moth-eye (moth-eye) structure, in which 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, the reflection in a wavelength range 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 dependence over a wide wavelength range, can be applied to many materials, and can directly form an uneven pattern on a substrate. As a result, a low-cost, 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 manufacturing an antireflection film (or an 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 a “moth-eye mold”) can be easily manufactured. In particular, as described in Patent Documents 2 and 3, when the surface of the aluminum anodic oxide film is used as it is as a mold, the effect of reducing the manufacturing cost is great. The surface structure of the moth-eye mold on which the moth-eye structure can be formed 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 (micro structure), by providing an uneven structure (macro structure) larger than the moth-eye structure, the anti-reflection film (anti-reflection surface) is formed. An anti-glare (anti-glare) function can be provided. The two-dimensional size of the projections or depressions forming the uneven structure exhibiting the anti-glare function (sometimes referred to as “anti-glare structure”) is 200 nm or more and less than 100 μm. In addition, the surface structure of a mold capable of forming an anti-glare structure is referred to as an “inverted anti-glare structure”. All of the disclosures of Patent Documents 1 to 4 are incorporated herein by reference.

  Note that, in this specification, irregularities forming a moth-eye structure (or an inverted moth-eye structure) are called micro unevenness, and unevenness forming an anti-glare structure (or an inverted anti-glare structure) is called macro unevenness. To Although the two-dimensional size range of the macro unevenness partially overlaps with the two-dimensional size range of the micro unevenness, the anti-glare film having the anti-glare function (anti-reflection surface) has an anti-glare effect. The concavo-convex structure constituting the structure is larger than the concavo-convex structure constituting the moth-eye structure exhibiting the antireflection function.

JP 2001-517319 A JP-T-2003-531962 International Publication No. 2011/055577 WO 2013/146656

  Various methods have been sought for a method of efficiently manufacturing a mold for forming an antireflection film (or antireflection surface) having an appropriate antiglare function.

  For example, in the sand blast method described in Patent Document 1, it is difficult to form a desired macro uneven structure having an antiglare function with good reproducibility. Further, in the cathodic electrolysis method described in Patent Literature 3, a macro uneven structure that can sufficiently exhibit an antiglare function may not be formed.

  Furthermore, the surface reflecting a continuous macro uneven structure without a flat portion of the resin layer formed by electrodeposition described in Patent Document 4 has a problem that an image is blurred. In recent years, as the definition of a display device has been improved, an anti-reflection film having an appropriate anti-glare function in which image blur has been suppressed has been demanded.

  The present inventor studied a method of manufacturing an antireflection film (or an antireflection surface) having an appropriate antiglare function and an appropriate specular reflectivity by a roll-to-roll method. It has been found that it is difficult to uniformly form an inverted anti-glare structure on the surface. This problem is a common problem in the technology for treating the surface of a columnar or cylindrical substrate.

  An object of the present invention is to provide a method capable of uniformly treating the surface of a columnar or cylindrical substrate.

  The method for treating the surface of a substrate according to an embodiment of the present invention is a method for treating the surface of a columnar or cylindrical substrate, wherein (a) the major axis direction of the substrate is substantially parallel to the horizontal direction. Rotating the base material around the long axis of the base material in a state where the base material is arranged as described above; and (b) storing a part of the outer peripheral surface of the base material in the first etching tank. Contacting with the first etching solution.

  In one embodiment, the method further includes a step (c) of spraying a second etching solution, which is the same as the first etching solution, onto the outer peripheral surface of the base material.

  In one embodiment, the step (c) is performed at the same time as the step (b), and the second etchant is provided on a portion of the outer peripheral surface of the base material that is in contact with the first etchant. It is sprayed near.

  In one embodiment, the step (c) is performed at the same time as the step (a), and the second etchant is provided on a portion of the outer peripheral surface of the base material that is in contact with the first etchant. It is sprayed on the vicinity, which is rotating in the step (a) away from the first etchant.

  In one embodiment, in the step (c), the angle at which the second etchant is jetted is inclined at an angle of 45 ° or more and less than 90 ° from a vertical direction.

  In one embodiment, the substrate is an aluminum substrate formed of an Al-Mg-Si-based aluminum alloy and mechanically mirror-finished.

  In one embodiment, the first etching solution is an aqueous solution containing a salt of hydrogen fluoride and ammonium.

  In one embodiment, the salt of hydrogen fluoride and ammonium is ammonium fluoride.

  In one embodiment, before the step (b), the method further includes a step (b1) of bringing a part of the outer peripheral surface of the base material into contact with a third etchant different from the first etchant. (3) An etching rate of the first etching solution to the outer peripheral surface of the substrate is lower than an etching rate of the first etching solution to the outer peripheral surface of the substrate.

  In one embodiment, the third etching solution is an etching solution obtained by diluting the first etching solution.

  In one embodiment, the third etching liquid has a lower temperature than the first etching liquid.

  In one embodiment, the third etching solution is contained in a second etching tank different from the first etching tank.

  In one embodiment, the third etching liquid is contained in the first etching tank.

  In one embodiment, after the step (b), the method further includes a step (b2) of bringing a part of the outer peripheral surface of the base material into contact with a fourth etchant different from the first etchant. An etching rate of the etchant on the outer peripheral surface of the substrate is lower than an etching rate of the first etchant on the outer peripheral surface of the substrate.

  In one embodiment, the fourth etchant is the same etchant as the third etchant.

  In one embodiment, in the step (a), the peripheral speed of the base material is more than 0 m / s and 0.03 m / s or less.

  In one embodiment, in the step (a), the rotation speed of the base material is more than 0 rpm and 2 rpm or less.

  The method for manufacturing a mold according to the embodiment of the present invention is characterized in that (A) a cylindrical aluminum substrate formed of an Al-Mg-Si-based aluminum alloy, wherein the aluminum substrate is mechanically mirror-finished; And (B) a step of treating the surface of the aluminum base material by any of the surface treatment methods described above; and (C) after the step (B), on the surface of the aluminum base material. Forming an inorganic material layer and forming an aluminum film on the inorganic material layer to form a mold base; and (D) after the step (C), applying a surface of the aluminum film to an anode. Oxidizing to form a porous alumina layer having a plurality of micro concave portions; and (E) contacting the porous alumina layer with an etching solution after the step (D). Wherein comprising a step of expanding the plurality of microscopic concave portion of the porous alumina layer, and a step after the, to further by anodic oxidation, growing said plurality of microscopic recesses (F) the step (E).

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

  In one embodiment, the pH of the alkaline etchant is 8 or more and 10 or less.

  In one embodiment, the alkaline etching solution is prepared by adding an acidic additive to an aqueous solution containing an organic compound having an amino group.

  In one embodiment, the volume of the acidic additive is 5% or more based on the volume of the aqueous solution containing the organic compound having an amino group.

  A mold according to an embodiment of the present invention is a mold manufactured by the method for manufacturing a mold according to any of the above.

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

  The method for manufacturing an antireflection film according to the embodiment of the present invention includes a step of preparing any one of the above-described molds, a step of preparing a workpiece, and a photocuring process between the mold and the surface of the workpiece. In a state where the resin is applied, a step of curing the photocurable resin by irradiating the photocurable resin with light, and a step of peeling the mold from an antireflection film formed of the cured photocurable resin. Is included.

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

  According to the embodiment of the present invention, the surface of a columnar or cylindrical substrate can be uniformly treated.

(A)-(d) is typical sectional drawing for demonstrating the manufacturing method of the moth-eye type | mold 100 by embodiment of this invention, (a) is the aluminum base 12 of the moth-eye type | mold 100. It is a schematic sectional view, (b) is sectional drawing which shows typically the surface structure of the aluminum base material 12 which has the inverted anti-glare structure, (c) is an inorganic base material on the surface of the aluminum base material 12. FIG. 4D is a schematic cross-sectional view of the mold base 10 on which the material layer 16 and the aluminum film 18 are formed, and FIG. 4D shows an inverted anti-glare structure and an inverted moth-eye structure superimposed on the inverted anti-glare structure. 1 is a schematic cross-sectional view of a moth-eye mold 100 having (A) is a schematic plan view of the inverted anti-glare structure, and (b) is a schematic perspective view of the inverted anti-glare structure. It is a figure for explaining a manufacturing method of an anti-reflection film using moth eye model 100. (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 observing the surface of the antireflection film from a vertical direction, (B) is a schematic diagram when the surface of the antireflection film is observed from an oblique direction, and (c) is a schematic diagram of a cross section of the antireflection film. (A) And (b) is a schematic diagram for demonstrating the surface treatment method of the base material by embodiment of this invention. (A) is a schematic diagram for explaining a substrate surface treatment method according to a comparative example, and (b) is manufactured by a mold manufacturing method using the substrate surface treatment method according to the comparative example. FIG. 4 is a schematic plan view when the antireflection film 32 manufactured using the moth-eye mold 100 is observed from the normal direction of the antireflection film 32. (A) is a schematic diagram when the antireflection film 32 manufactured using the moth-eye mold 100 manufactured by the method for manufacturing a mold according to the embodiment of the present invention is observed from the normal direction of the antireflection film 32. FIG. 3B is a schematic view for explaining a step of matte-treating the surface of the aluminum base material 12 in the process of manufacturing the moth-eye mold 100, and illustrates a cylindrical aluminum base material. FIG. 12 is a schematic view as viewed from a long axis direction of a twelfth embodiment. (A) And (b) is a schematic diagram for demonstrating the surface treatment method of the base material by embodiment of this invention. (A) And (b) is a schematic diagram for demonstrating the surface treatment method of the base material by embodiment of this invention. (A) is a schematic diagram for explaining the surface treatment method of the base material according to the embodiment of the present invention, (b) is the length of the aluminum base material 12 generated on the outer peripheral surface of the aluminum base material 12 It is a schematic diagram for demonstrating the several streak-like unevenness extended in the direction substantially orthogonal to an axial direction, (c) and (d) are schematic diagrams for demonstrating the angle which the etching liquid for spraying is blown off. FIG. (A) and (b) are views showing an optical image of the aluminum base material 12, and (a) shows a matte finish by a surface treatment method that does not include a step of spraying a spraying etching solution onto the outer peripheral surface of the aluminum base material 12. (B) is an aluminum substrate 12 that has been subjected to a satin finish treatment by a surface treatment method including a step of spraying a spray etching solution onto the outer peripheral surface of the aluminum substrate 12. . (A) to (d) show the surface of an aluminum substrate having an inverted anti-glare structure formed by the satin finish process of Experimental Examples 1-1, 2-1 and 4-1. FIG. 3 is a diagram showing optical microscope images (50 ×) when the image is observed from the vertical direction, and (e) to (h) show experimental examples 1-1, 2-1, 3-1 and 4- FIG. 4 is a diagram showing a SEM image (full scale of 20 μm in the SEM image) when the surface of the antiglare film formed from the aluminum base material No. 1 is observed from a vertical direction. (A) to (e) show inverted antiglare formed by the satin finish process of Experimental Examples 1-2, 1-3, 2-2, 3-2, and 4-2. It is a figure which shows the optical microscope image (50 times) when observing the surface of the aluminum base material which has a structure from a perpendicular direction. (A) to (d) are optical microscope images when the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 5-1 to 5-4 is observed from a vertical direction ( (E) and (f) are SEM images when the surface of the antiglare film formed from the aluminum base material of Experimental Examples 5-3 and 5-4 was observed from the vertical direction ( It is a figure which shows the full scale in a SEM image (20 micrometers). (A) and (b) are optical microscope images (observed from a vertical direction) of the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 6-1 and 6-2. FIG. (A) is a figure which shows the optical microscope image (50 times) when observing the surface of the aluminum base material which performed the alkali washing process of Experimental Example 7-1 from a perpendicular direction, (b) and (c). 7) is a diagram showing an SEM image (full scale of 20 μm in the SEM image) when the surface of the polymer film formed from the aluminum base material of Experimental Examples 7-1 and 7-2 is observed from the vertical direction. (A) to (d) are optical microscope images (observed from a vertical direction) of the surface of an aluminum substrate having an inverted anti-glare structure formed by the satin finish process of Experimental Examples 8-1 to 8-4. (E) to (h) are SEM images of the surface of the polymer film formed from the aluminum base material of Experimental Examples 8-1 to 8-4 when observed from the vertical direction. FIG. 4 is a diagram showing (full scale in a SEM image: 20 μm). (A) to (d) are optical microscope images when the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 9-1 to 9-4 is observed from a vertical direction ( FIG. (A) to (d) are optical microscopic images (observed from a vertical direction) of the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 10-1 to 10-4 ( (E) to (h) are SEM images when the surface of the polymer film formed from the aluminum base material of Experimental Examples 10-1 to 10-4 is observed from the vertical direction. FIG. 4 is a diagram showing (full scale in a SEM image: 20 μm). (A) is a figure which shows the relationship between the time of an alkali washing | cleaning process, and the mass change rate of an aluminum base material, (b), The time of an alkali washing process, and the anti-glare obtained using an aluminum base material as a type | mold. FIG. 3 is a diagram showing a relationship with a haze value of a film. (A) and (b) are optical microscope images when the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 11-1 and 11-2 is observed from a vertical direction ( (C) and (d) are SEM images when the surface of the polymer film formed from the aluminum base material of Experimental Examples 11-1 and 11-2 is observed from the vertical direction. FIG. 4 is a diagram showing (full scale in a SEM image: 20 μm). (A) and (b) are figures which show typically the relationship of the magnitude | size of the macro uneven structure for forming the conventional anti-glare structure, and the dot pitch Px of a row direction. FIG. 2A is a cross-sectional view schematically illustrating a conventional macroscopic uneven structure for forming an anti-glare structure, and FIG. 2B is a schematic cross-sectional view illustrating an inverted moth-eye structure superimposed on the macro unevenness. It is a figure and (c) is the typical cross section which expanded the inverted moth-eye structure.

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

  First, with reference to FIG. 22, a description will be given of the relationship between the macro uneven structure forming the conventional anti-glare structure and the dot pitch Px in the row direction. FIGS. 22A and 22B are diagrams schematically showing the relationship between the size of a macro uneven structure forming the conventional antiglare structure and the dot pitch Px in the row direction. Shows the case where the macro uneven structure is larger than the dot pitch Px, and FIG. 22B shows the case where the macro uneven structure is smaller than the dot pitch Px. Here, the dots indicate R, G, and B dots forming pixels in a typical color liquid crystal display panel. That is, when the pixels in the color liquid crystal display panel are composed of three dots (R dots, G dots, and B dots) arranged in the row direction, the pixel pitch in the row direction is equal to the dot pitch Px in the row direction. 3 times. 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. 22A and 22B, the surface 28s having the macro uneven structure constituting the conventional antiglare structure has a continuous waveform surface shape having no flat portion. The macro uneven structure having such a continuous waveform surface shape is characterized by the average value of the distance between adjacent macro concave portions (average distance between adjacent adjacent portions AD _int ) or the two-dimensional size AD _p of the concave portion. . Here, attention is focused on the macro concave portion, but the same can be characterized by focusing on the convex portion.

As shown in FIG. 22 (a), (considered to be equal to 2-dimensional size AD _p recess) average distance between adjacent AD _int concave portions, for example, a row direction of the dot pitch Px (pixel has three dots ( In the case of R, G, B), if the pixel pitch in the row direction is larger than three times the dot pitch), a sufficient anti-glare function cannot be obtained. In order to sufficiently exhibit the anti-glare function, as shown in FIG. 22 (b), the average distance AD _int between the concave portions (the two-dimensional size AD _{p of the} concave portions) is substantially equal to each other, and the dot pitch is small. It is preferably smaller than. Note that the two-dimensional size of the concave portion refers to a two-dimensional spread when viewed from the normal direction of the surface, and the concave portion is typically conical, and when viewed from the normal direction of the surface. Has a substantially circular shape. At this time, the two-dimensional size corresponds to the diameter of the circle. Also, if protrusions only be formed at a sufficiently high density, the average distance between adjacent AD _int the two recesses adjacent to each other is approximately equal to 2-dimensional size AD _p of the recessed portion. The pixel pitch is 254 μm for a display having a relatively low resolution, for example, a display of 100 ppi. In the case of the antireflection film used in this display, the average distance between adjacent pixels AD _int is preferably about 85 μm (254/3) or less.

  A method of manufacturing an antireflection film in which a moth-eye structure is superimposed on an anti-glare structure having a continuous waveform surface 28s without a flat portion is described in, for example, Patent Document 4. With reference to FIG. 23, a description will be given of a method for manufacturing a moth-eye mold for forming an anti-reflection film having an anti-glare function described in Patent Document 4.

  FIG. 23A is a cross-sectional view schematically showing an inverted anti-glare structure for forming an anti-glare structure, and FIG. 23B is an inverted moth-eye structure superimposed on the inverted anti-glare structure. FIG. 23C is a schematic cross-sectional view in which the inverted moth-eye structure is enlarged.

  The surface 18cs having the inverted anti-glare structure for forming the anti-glare structure having the continuous corrugated surface 28s without the flat portion shown in FIG. 23 (a) is the outer peripheral surface of the cylindrical metal base material. It is obtained by forming an insulating layer with an electrodeposition resin containing a matting agent thereon and forming an aluminum film 18c on the insulating layer. That is, the surface of the insulating layer formed of the electrodeposition resin containing the matting agent has a continuous waveform surface shape without a flat portion, and the surface 18cs of the aluminum film 18c formed on the insulating layer is Reflecting the surface shape of the insulating layer, the insulating layer has a continuous waveform surface shape without a flat portion. Since the shape of the surface 18cs of the aluminum film 18c constitutes an inverted anti-glare structure, the macro unevenness of the surface 18cs of the aluminum film 18c has a reverse relationship to the macro unevenness of the surface 28s forming the anti-glare structure. is there.

  Next, as shown in FIG. 23B, anodic oxidation and etching are alternately repeated on the surface of the inverted aluminum film 18c having an antiglare structure, thereby forming an anodized porous film having a micro concave portion 14p. The alumina layer 14c is formed. In this manner, a moth-eye mold 200 having a surface on which the inverted moth-eye structure is superimposed on the inverted anti-glare structure is obtained.

As shown schematically in FIG. 23C, the porous alumina layer 14c is densely filled with the micro concave portions 14p. The micro concave portion 14p is generally conical and may have a stepped side surface. The two-dimensional size of a microscopic concave portion 14p (opening diameter: D _p) is preferably less than 500nm or 10nm, the depth (D _depth) is less than about 10nm or 1000 nm (1 [mu] m). It is preferable that the bottom of the micro concave portion 14p is sharp (the bottom is a dot). Furthermore, it is preferable that the micro concave portions 14p are densely filled, 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 saddle portion is formed between adjacent micro concave portions 14p. When the substantially conical micro concave portions 14p are adjacent to each other so as to form a saddle 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 manufacturing the anti-reflection film has a dense micro concave portion 14p having 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 a structure arranged irregularly. The arrangement of the micro concave portions does not need to be completely random, but may be irregular so long as light interference or diffraction does not substantially occur. Note that since the shape of the opening of the micro concave portion 14p is not strictly a circle, it is preferable to obtain D _p from an SEM image of the surface. The thickness t _p of the porous alumina layer 14c is about 1μm 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.

An antireflection film formed using a mold manufactured by the method for manufacturing a mold described in Patent Document 4 has a problem that an image is blurred. 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, with the manufacturing method described in Patent Document 4, it was difficult to form an anti-glare structure suitably used for a high-definition display exceeding 300 ppi, for example.

  According to the embodiments of the present invention described below, an anti-glare structure having an appropriate anti-glare function (for example, a haze value of about 10 or more and about 50 or less), an appropriate specular reflectivity, and an excellent anti-reflection effect are exhibited. An anti-reflective coating (or anti-reflective surface) having a moth-eye structure is provided. Further, according to an 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. The mold manufactured by the mold manufacturing method according to the embodiment of the present invention is not limited to the example, and forms an antireflection film having a diffuse reflection performance with a small haze value (for example, about 2 or more and about 10 or less). Can also be used for

  First, a method for manufacturing a mold according to an embodiment of the present invention and a structure of the mold manufactured by such a manufacturing method will be described with reference to FIGS.

  1A to 1D are schematic cross-sectional views illustrating a method for manufacturing a moth-eye mold 100 according to an embodiment of the present invention.

The method for manufacturing the moth-eye mold 100 according to the embodiment of the present invention includes the following steps (i) to (vi).
Step (i): a step of preparing a cylindrical aluminum substrate formed of an Al-Mg-Si-based aluminum alloy and having been subjected to mechanical mirror finishing.
Step (ii): a step of subjecting the surface of the aluminum substrate to satin finish with an aqueous solution containing a salt of hydrogen fluoride and ammonium (sometimes referred to as satin finish step).
Step (iii): a step of forming a mold base by forming an inorganic material layer on the surface of the aluminum base material and forming an aluminum film on the inorganic material layer after the step (ii).
Step (iv): a step of forming a porous alumina layer having a plurality of micro concave portions by anodizing the surface of the aluminum film after the step (iii).
Step (v): a step of enlarging a plurality of micro concave portions of the porous alumina layer by bringing the porous alumina layer into contact with an etching solution after the step (iv).
Step (vi): a step of growing a plurality of micro concave portions by further anodic oxidation after the step (v).

  In the present specification, the mold base refers to an object to be anodized and etched in a mold manufacturing process. In addition, the aluminum base material refers to a self-supporting bulk aluminum.

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

  FIG. 1 shows an enlarged part of the moth-eye mold 100. The moth-eye mold 100 according to the 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 manufactured by a roll-to-roll method. The entire disclosure of WO 2011/105206 is incorporated herein by reference.

[Aluminum substrate]
First, as shown in FIG. 1A, a cylindrical aluminum substrate 12 formed of an Al-Mg-Si-based aluminum alloy, which is a mechanically mirror-finished aluminum substrate 12, is provided. prepare.

  As mechanical mirror finishing, cutting with a cutting tool is preferable. If, for example, abrasive grains remain on the surface of the aluminum base material 12, conduction is easily made between the aluminum film 18 and the aluminum base material 12 in a portion where the abrasive grains are present. Where there are irregularities other than the abrasive grains, local conduction between the aluminum film 18 and the aluminum base material 12 becomes easy. When local conduction occurs between the aluminum film 18 and the aluminum substrate 12, a battery reaction may occur locally between the impurities in the aluminum substrate 12 and the aluminum film 18.

  As the aluminum base 12, an aluminum base 12 formed of an Al-Mg-Si-based aluminum 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 porthole 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 porthole method, and the seam is reflected on 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.

  By subjecting the aluminum base material 12 formed by the porthole method to cold drawing, the problem of the seam can be solved. Of course, cold drawing may be performed on the aluminum base material 12 formed by the mandrel method.

[Sashimi processing step using an aqueous solution containing a salt of hydrogen fluoride and ammonium]
Next, the surface of the aluminum base 12 is subjected to a matte finish using 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 finish 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 like 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 (pitting). 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. 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). Since the aqueous solution containing ammonium fluoride has a weaker aluminum etching power than the aqueous solution containing ammonium hydrogen fluoride, there is obtained an advantage that the time margin of the satin finish can be increased. In addition, ammonium fluoride has an advantage that it is superior in safety to ammonium hydrogen fluoride.

  When ammonium fluoride is used as the salt between hydrogen fluoride and ammonium, the concentration of ammonium fluoride is, for example, 4 mass% to 8 mass%. In addition to ammonium fluoride, ammonium sulfate and / or ammonium dihydrogen phosphate may be added. Here, including the following experimental examples, an etchant obtained by adding ammonium sulfate and ammonium dihydrogen phosphate to ammonium fluoride was used as an etchant for treating aluminum in a satin finish. For example, a mixture obtained by adding ammonium sulfate (concentration: 1 mass% to 3 mass%) and ammonium dihydrogen phosphate (concentration: 1 mass% to 3 mass%) to ammonium fluoride (concentration: 4 mass% to 8 mass%) can be used. . For example, the concentration of ammonium fluoride is preferably 5% by mass, the concentration of ammonium sulfate is preferably 2% by mass, and the concentration of ammonium dihydrogen phosphate is preferably 2% by mass.

  Note that, even when an aqueous solution containing ammonium hydrogen fluoride is used as a salt of hydrogen fluoride and ammonium, the concentration, the treatment temperature, and the time are appropriately adjusted to obtain an aqueous solution containing ammonium fluoride. It is considered that an equivalent effect can be obtained. The aqueous solution containing ammonium hydrogen fluoride has a stronger aluminum etching power than the aqueous solution containing ammonium fluoride. The aqueous solution containing ammonium hydrogen fluoride can be prepared, for example, by using a chemical cleaner manufactured by C.B.C. The applicant of the present application discloses, in WO 2015/159797, an experimental example in which a satin finish treatment is performed using ammonium hydrogen fluoride as a salt of hydrogen fluoride and ammonium. The entire disclosure of WO 2015/159797 is incorporated herein by reference.

[Alkali washing step]
A step of etching the surface of the aluminum base material 12 using an alkaline etchant before the step (step (ii)) of subjecting the surface of the aluminum base material to a satin finish treatment with an aqueous solution containing a salt of hydrogen fluoride and ammonium (Vii) (hereinafter sometimes referred to as “alkali washing step”) may be further performed. By the alkali cleaning step using an alkaline etching solution, at least a part of the work-affected layer of the aluminum base 12 that may cause cutting marks can be removed.

  According to the study of the present inventor, when a matte finish is applied to the aluminum base material 12 which has been mirror-finished by cutting with a cutting tool, cutting marks may be formed on the surface of the aluminum base material 12. The cutting marks formed on the surface of the aluminum base 12 were also reflected on the aluminum film 18 formed on the aluminum base 12. In the present specification, not only the surface of the aluminum base 12 but also the marks formed on the aluminum film 18 formed on the aluminum base 12 due to cutting are referred to as “cutting marks”.

  The above-mentioned cutting marks are considered to be etching unevenness caused by a work-affected layer formed on the surface of the aluminum base material 12 by mirror finishing by cutting with a cutting tool. Therefore, the problem that the cutting marks are formed by the satin finish is not limited to the bite cutting, and is a common problem when using the mirror-finished aluminum base material 12 with the formation of a work-affected layer. This can be solved by performing a process. Of mirror finishing, cutting, mechanical polishing such as grinding (Mechanical Polishing: MP), and chemical mechanical polishing (Chemical Mechanical Polishing: CMP), which combines chemical polishing and mechanical polishing, form a damaged layer. Accompany. As used herein, “mechanical mirror finishing” includes MP and CMP.

  The alkaline etching solution for the alkaline cleaning step 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. Organic bases include, for example, compounds 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, more than 7 and 12 or less, and preferably 8 or more and 10 or less. The alkaline etching solution is not limited to the above, and for example, a known alkaline cleaning solution may be used. The pH of the alkaline etching solution may be adjusted by adding a small amount of an acidic additive (for example, a chemical polishing agent or a corrosion inhibitor) to the alkaline cleaning solution to prepare an alkaline etching solution. The composition and pH of the alkaline etching solution will be described later with reference to experimental examples. Since the alkaline cleaning step uses an alkaline etching solution, it can also serve as a degreasing step for the aluminum base material.

  After the alkali washing step, a water washing step is performed, if necessary, before the satin finish treatment step using an aqueous solution containing a salt of hydrogen fluoride and ammonium. Further, the present invention is not limited to this, and it is preferable to perform water washing as needed between steps using different treatment liquids.

  Instead of the alkali cleaning step, an anodic oxidation step and an etching step for pretreatment may be performed before the satin finish step. By performing an anodic oxidation step and an etching step for pretreatment, cutting marks can be reduced. That is, the surface of the aluminum base material 12 is once anodized, and the formed anodized film is removed by etching, so that cutting marks can be reduced. In the anodizing step for the pretreatment, it is preferable to use an aqueous solution of sulfuric acid as the electrolytic solution, and in the etching step for the pretreatment, it is preferable to use an aqueous solution of phosphoric acid as the etching solution.

  Both the alkali cleaning step, the anodic oxidation step for pretreatment, and the etching step may be performed before the satin finish step. For example, the alkali cleaning step may be performed before the anodic oxidation step for pretreatment and the etching step.

[Inorganic material layer]
Next, as shown in FIG. 1C, the mold base 10 is formed by forming an inorganic material layer 16 on the surface of the aluminum base 12 and forming an aluminum film 18 on the inorganic material layer 16. I do.

  On the surface of the aluminum film 18, a structure reflecting the inverted anti-glare structure formed by performing a satin finish on the surface of the aluminum base 12 is formed. Here, the structure formed on the aluminum film 18 is also called an inverted anti-glare structure. The inverted anti-glare structure formed on the surface of the aluminum film 18 has substantially the same structure as the inverted anti-glare 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, for example, a sputtering method. 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. 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 perform anodic oxidation of the aluminum film 18 by supplying a current to the aluminum film 18 from the aluminum base 12 side, a current needs to flow between the aluminum base 12 and the aluminum film 18. If a configuration in which current is supplied from the inner surface of the cylindrical aluminum base material 12 is adopted, 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 can be increased as the anodization proceeds. Does not occur, and the aluminum film 18 can be uniformly anodized over the entire surface.

  Further, in order to form the thick inorganic material layer 16, it is generally necessary to lengthen the film formation time. When the film forming time is long, the surface temperature of the aluminum base 12 is unnecessarily increased, and 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.

[Aluminum film]
The aluminum film 18 is, for example, a film formed of aluminum having a purity of 99.99 mass% or more (hereinafter, sometimes referred to as a “high-purity aluminum film”), as described in Patent Document 3. The aluminum film 18 is formed using, for example, a vacuum evaporation 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.

  Further, as the aluminum film 18, an aluminum alloy film described in WO 2013/0183576 may be used instead of the high-purity aluminum film. The aluminum alloy film described in WO 2013/0183576 contains aluminum, a metal element other than aluminum, and nitrogen. In this specification, the “aluminum film” includes not only a high-purity aluminum film but also an aluminum alloy film described in WO 2013/0183576. The entire disclosure of WO 2013/0183576 is incorporated herein by reference.

  When the aluminum alloy film is used, a mirror surface having a reflectance of 80% or more can be obtained. The average grain size of the crystal grains constituting the aluminum alloy film when 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 of nitrogen contained in the aluminum alloy film is, for example, 0.5 mass% or more and 5.7 mass% or less. 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. The metal element is, for example, Ti or Nd. However, the metal element is not limited to this, and other metal elements (for example, Mn, Mg, Zr, V, and the like) 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. Pb). Further, the metal element may be Mo, Nb or Hf. The aluminum alloy film may include 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 or more and about 1500 nm or less, for example, about 1 μm.

  Here, the inverted anti-glare structure will be described in detail with reference to FIGS. 2 (a) and 2 (b). FIG. 2A is a schematic plan view of the inverted anti-glare structure, and FIG. 2B is a schematic perspective view of the inverted anti-glare structure.

  As shown in FIGS. 2A and 2B, the inverted anti-glare structure formed by the satin finish 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.

  The plurality of macro convex portions 18p have a substantially polygonal outer shape when viewed from the normal direction of the surface, but do not have regularity in 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. The upper surface of the macro convex portion 18p is substantially flat.

The width of the macro concave portion (groove) 18g substantially surrounding the macro convex portion 18p is about 1/10 to 1/5 of the two-dimensional size of the macro convex portion 18p. . The average value of the distance between the adjacent macro concave portions 18g (average inter-adjacent distance AD _int ) is substantially 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. You 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. In the cross section in the direction, it means the adjacent macro concave portion 18g. Therefore, the average adjacent distance AD _int is substantially equal to the sum of the average value of the two-dimensional size of the macro convex portion 18p and the average value of the width of the macro 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 an inverted moth-eye structure, thereby obtaining the moth-eye mold 100 shown in FIG. 1D. That is, the process of forming the inverted moth-eye structure includes a step of forming a porous alumina layer 14 having a plurality of micro concave portions 14 p by anodizing the surface of the aluminum film 18, and thereafter, a step of forming the porous alumina layer 14. Is contacted with an etching solution to expand the plurality of micro recesses 14p of the porous alumina layer 14, and thereafter, a step of growing the plurality of micro recesses 14p by further anodic oxidation is included. I do. The electrolyte used for the anodic oxidation 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 the etchant, an aqueous solution of an organic acid such as formic acid, acetic acid, or citric acid or sulfuric acid, a mixed aqueous solution of phosphoric acid and chromic acid, or an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be used.

  It is preferable that a series of steps of repeating the anodic oxidation and the etching end with the anodic oxidation step. By ending with the anodizing step (without performing the subsequent etching step), 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 present applicant. The entire disclosure of WO 2006/059686 is incorporated herein by reference.

For example, an anodizing step (electrolyte: oxalic acid aqueous solution (concentration 0.3 mass%, liquid temperature 10 ° C.), applied voltage: 80 V, application time: 55 seconds) and an etching step (etching liquid: phosphoric acid aqueous solution (10 mass%, 30 ° C.) ) And etching time: 20 minutes) are alternately repeated a plurality of times (for example, 5 times: 5 times of anodic oxidation and 4 times of etching) to form a micro concave portion 14p as shown in FIG. A moth-eye mold 100 having the porous alumina layer 14 is obtained. As described with reference to FIG. 23C, 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 15 are densely arranged irregularly. The micro concave portion 14p has a substantially conical shape and is adjacent to form a saddle portion.

  The inverted moth-eye structure constituted by the micro concave portions 14p is formed so as to overlap the anti-glare structure. Therefore, as schematically shown in FIG. 1D, the micro concave portion 14p formed in the macro convex portion 18p constituting the anti-glare structure and the micro concave portion 14p formed in the macro concave portion 18g are formed. 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.

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

  As described above, according to the method for manufacturing the moth-eye mold 100 according to the embodiment of the present invention, the moth-eye mold 100 capable of forming an antireflection film having an anti-glare function can be manufactured. The anti-glare function of the antireflection film formed using the moth-eye mold 100 will be described later in detail with reference to experimental examples.

  Next, a method for manufacturing an antireflection film using the moth-eye mold 100 will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view for explaining a method of manufacturing an antireflection film by a roll-to-roll method.

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

  As shown in FIG. 3, the workpiece 42 having the surface thereof coated with the ultraviolet curable resin 32 ′ is pressed against the moth-eye mold 100, and the ultraviolet curable resin 32 ′ is irradiated with ultraviolet light (UV). The cured resin 32 'is cured. As the ultraviolet curing 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 unwind roller, and then the surface of the workpiece 42 is coated with the ultraviolet curable resin 32 '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 transport the workpiece 42. Further, the cylindrical moth-eye mold 100 is rotated in a direction indicated by an arrow in FIG. 3 at a rotation speed corresponding to the transport speed of the workpiece 42.

  Thereafter, by separating the moth-eye mold 100 from the workpiece 42, the cured product layer 32 to which the concave-convex structure (the 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 material layer 32 formed on the surface is wound by a winding roller (not shown).

  4A to 4C, the structure of the antireflection film 32 having an antiglare function according to the embodiment of the present invention will be described. FIGS. 4A to 4C are schematic diagrams of the antireflection film 32 having an antiglare function according to the embodiment of the present invention. FIG. 4A shows the surface of the antireflection film 32 when observed from a vertical direction. FIG. 4B is a schematic diagram when the surface of the antireflection film 32 is observed from an oblique direction, and FIG. 4C is a schematic diagram of a cross section of the antireflection film 32.

  4A to 4C, the plurality of micro convex portions forming the moth-eye structure include micro convex portions 32p and 32g. The micro convex portion 32p is formed in a macro concave portion constituting an anti-glare structure, and the micro convex portion 32g is formed in a macro convex portion constituting an anti-glare structure. Therefore, the micro convex portion 32g is higher than the micro convex portion 32p and is disposed so as to substantially surround the micro convex portion 32p formed in the macro concave portion. This corresponds to the fact that the macro convex portion 18p was substantially surrounded by the macro concave portion 18g in the inverted anti-glare structure formed by the satin finish in the process of manufacturing the moth-eye mold 100. .

[Substrate surface treatment method]
According to the study of the present inventor, in the process of manufacturing the cylindrical moth-eye mold 100, the inverted anti-glare structure formed by the satin finish is not uniformly formed on the surface of the aluminum substrate 12. In some cases, macro unevenness occurred on the surface of No. 12. According to the study by the present inventors, there are cases where there are a plurality of causes of macro unevenness. This problem is a common problem in the technology for treating the surface of a columnar or cylindrical substrate. The present inventor has studied a surface treatment method for a base material that can suppress the occurrence of macro unevenness.

  With reference to FIGS. 5A and 5B, a method for treating a surface of a substrate according to an embodiment of the present invention will be described. FIGS. 5A and 5B are schematic diagrams for explaining a surface treatment method for a base material according to an embodiment of the present invention.

The method for treating the surface of a substrate according to an embodiment of the present invention is a method for treating the surface of a columnar or cylindrical substrate, and includes the following steps (I) and (II).
Step (I): a step of rotating the base material around the long axis of the base material in a state where the base material is arranged such that the major axis direction of the base material is substantially parallel to the horizontal direction.
Step (II): a step of bringing a part of the outer peripheral surface of the base material into contact with the first etching solution contained in the first etching tank.

  Here, the step of matte-treating the surface of the aluminum base material with an aqueous solution containing a salt of hydrogen fluoride and ammonium (matte processing step), which is included in the mold manufacturing method according to the embodiment of the present invention, includes: An example using a surface treatment method will be described. However, the method for treating the surface of the substrate according to the embodiment of the present invention is not limited to this. For example, the surface of the aluminum film may be anodized to form a porous alumina layer having a plurality of micro concave portions, or the porous alumina layer may be contacted with an etching solution to form a porous alumina layer. May be used in the step of enlarging the plurality of micro concave portions. Furthermore, the present invention is not limited to the mold manufacturing method according to the embodiment of the present invention, and can be widely used as a method for treating the surface of a columnar or cylindrical substrate. The surface treatment of the base material includes, for example, various chemical treatment steps such as an etching step, a cleaning step, a film forming step, and a plating step. A method of treating the surface (side surface) of a cylindrical substrate or the surface (outer peripheral surface) of a cylindrical substrate may be used, or the surface (side surface) of a cylindrical substrate or the cylindrical substrate may be treated. A method of treating a metal film or an oxide film provided on the surface (outer peripheral surface) may be used. The surface of the substrate may be a metal or an oxide.

  As shown in FIG. 5A, a cylindrical aluminum base material 12 and a first etching tank 51 are prepared. The first etching bath 51 contains a first etching solution E1. The first etching solution E1 is, for example, an etching solution for satin finish, and is, for example, an aqueous solution containing a salt of hydrogen fluoride and ammonium. The length of the aluminum base 12 in the major axis direction is H, and the diameter of the outer peripheral surface in a cross section orthogonal to the major axis direction is D. As shown in FIG. 5B, by bringing a part of the outer peripheral surface of the aluminum base material 12 into contact with the first etching solution E <b> 1 stored in the first etching tank 51, the outer peripheral surface of the aluminum base material 12 is patterned. Perform processing. The aluminum base 12 is rotated around the long axis of the aluminum base 12 in a state where the long axis of the aluminum base 12 is arranged parallel to the horizontal direction. While rotating the aluminum base 12, a part of the outer peripheral surface of the aluminum base 12 may be brought into contact with the first etchant E <b> 1 stored in the first etching tank 51. That is, the steps (I) and (II) may be performed simultaneously.

  In the method for treating the surface of a substrate according to the embodiment of the present invention, the surface of the substrate can be uniformly treated by rotating the aluminum substrate 12. In the method for treating the surface of the base material according to the embodiment of the present invention, by rotating the aluminum base material 12, the entire aluminum base material 12 is not immersed in the first etching solution contained in the first etching tank 51. In addition, the outer peripheral surface of the aluminum base 12 can be subjected to the satin finish evenly. Therefore, it is possible to suppress the cost for the etching solution and the increase in the installation place of the etching bath. Further, since a part of the outer peripheral surface of the aluminum base material is brought into contact with the first etching solution E1 stored in the first etching bath 51, the first etching solution stored in the first etching bath 51 has It is easier to circulate the first etching solution E1 in the first etching tank 51 than in a case where the whole is immersed.

  In the above step (I), the peripheral speed of the aluminum base 12 is, for example, more than 0 m / s and 0.03 m / s or less. The rotation speed of the aluminum substrate 12 is, for example, more than 0 rpm and 2 rpm or less. If the rotation speed of the aluminum substrate 12 exceeds 2 rpm, the surface treatment of the substrate may not be performed uniformly. Here, since rpm is a unit representing the number of rotations per minute, a rotation speed of 1 rpm corresponds to a peripheral speed (π × D) / 60 (m / s). (In the present specification, “×” represents multiplication.) For example, when the aluminum base 12 having a cross section perpendicular to the long axis direction and having a diameter D of 0.3 m rotates at a rotation speed of 2 rpm, the peripheral speed is: 2 × π × D / 60 = 0.03 (m / s). In the step (I), the peripheral speed of the aluminum base 12 is preferably constant.

  With reference to FIG. 6, a method of surface treatment of a base material according to a comparative example will be described. In the substrate surface treatment method according to the comparative example, as shown in FIG. 6A, the long axis direction of the aluminum substrate 12 is disposed so as to be substantially parallel to the vertical direction, and the aluminum substrate 12 is accommodated in the etching tank 91. The outer peripheral surface of the aluminum substrate 12 is brought into contact with the etched etching solution. At this time, the entire aluminum substrate 12 is immersed in the etching solution in the etching tank 91. Therefore, the cost for the etching solution and the installation location of the etching tank 91 increase. For example, the depth of the etching bath 91 is larger than the length H of the aluminum base 12 in the major axis direction. Further, for example, considering that the aluminum base material 12 is hung from the top and taken in and out of the etching bath 91, the height of the ceiling where the etching bath 91 is installed is the length of the aluminum base material 12 in the major axis direction. It must be larger than twice H.

[Circumferential unevenness of substrate]
In the antireflection film 32 manufactured using the moth-eye mold 100 manufactured by the mold manufacturing method according to the embodiment of the present invention, periodic unevenness may occur.

  This will be described with reference to FIG. FIG. 7 is a schematic diagram for explaining the cause of the occurrence of periodic unevenness. FIG. 7A shows the anti-reflection film 32 manufactured using the moth-eye mold 100 manufactured by the mold manufacturing method according to the embodiment of the present invention when observed from the normal direction of the anti-reflection film 32. It is a schematic plan view. FIG. 7B is a schematic diagram for explaining a step of matte-treating the surface of the aluminum base 12 in the process of manufacturing the moth-eye mold 100, and illustrates the major axis of the cylindrical aluminum base 12. It is the schematic diagram seen from the direction.

  As shown in FIG. 7A, the anti-glare structure formed on the anti-reflection film 32 is periodically formed along the circumferential direction of the cylindrical aluminum base 12 (that is, the circumferential direction of the moth-eye mold 100). Has changed. This periodic unevenness is caused by unevenness of the inverted anti-glare structure formed on the surface of the moth-eye mold 100, and is performed in the manner described with reference to FIG. 3 (that is, in a roll-to-roll manner). This is because the anti-reflection film 32 was formed using 100. When a part of the outer peripheral surface of the aluminum substrate 12 is brought into contact with the first etching solution E1, the contact time and timing are not uniform depending on the position on the outer peripheral surface of the aluminum substrate 12, so that the satin finish is uniformly performed. However, the inverted anti-glare structure has unevenness. The anti-glare structure formed on the anti-reflection film 32 has a periodic unevenness having a period of π × D on the bottom surface of the aluminum substrate 12 and is visually recognized as a difference in the degree of scattering of visible light. In FIG. 7A, the anti-reflection film 32 is divided into periods π × D for easy viewing, but the anti-reflection film 32 is not divided into periods π × D. .

  In particular, as shown in FIG. 5 (b), when a part of the outer peripheral surface of the aluminum base material 12 is brought into contact with the first etchant E1, the position that first comes into contact with the first etchant E1 is the position of the aluminum base material. 12 is on a line L1 extending in the major axis direction of the aluminum base material 12 within the outer peripheral surface of the aluminum substrate 12. Since the line L1 first comes into contact with the first etching solution E1 in the outer peripheral surface of the aluminum base material 12, the satin finish processing with the first etching solution E1 proceeds fastest. That is, since the time of contact with the first etching solution E1 is the longest, the degree of progress of the satin finish is the highest. Further, when the line L1 first contacts the first etching solution E1 in the outer peripheral surface of the aluminum base material 12, since the impurities are small in the first etching solution E1 and on the surface of the aluminum base material 12, On the line L1, the progress speed of the satin finish tends to be the highest. Corresponding to the line L1 of the aluminum base material, linear irregularities sometimes appear on the antireflection film 32 periodically as shown by a broken line in FIG. 7A. On the outer peripheral surface of the aluminum base 12, linear irregularities extending in the major axis direction of the aluminum base 12 can be confirmed also in an optical image shown in FIG.

  In order to suppress the occurrence of periodic unevenness, the present inventor has conceived a method of performing a surface treatment with an etching solution having a small etching rate before and after the satin finish process. This will be described with reference to FIGS. FIG. 8 and FIG. 9 are schematic diagrams for explaining the method for treating the surface of the base material according to the embodiment of the present invention.

  In one embodiment, the method for treating a surface of a substrate according to an embodiment of the present invention includes, in one embodiment, the step (II) (a step of bringing a part of the outer peripheral surface of the substrate into contact with a first etching solution contained in a first etching tank). Before ()), a step (II-1) of bringing a part of the outer peripheral surface of the base material into contact with a second etchant (sometimes referred to as “pretreatment etchant”) different from the first etchant is further performed. Include. The etching rate of the second etchant on the outer peripheral surface of the substrate is lower than the etching rate of the first etchant on the outer peripheral surface of the substrate.

  In one embodiment, the method for treating a surface of a substrate according to an embodiment of the present invention includes, in one embodiment, the step (II) (a step of bringing a part of the outer peripheral surface of the substrate into contact with a first etching solution contained in a first etching tank). )) Further includes a step (II-2) of bringing a part of the outer peripheral surface of the base material into contact with a third etching solution (sometimes referred to as “post-processing etching solution”) different from the first etching solution. I do. The etching rate of the third etchant on the outer peripheral surface of the substrate is lower than the etching rate of the first etchant on the outer peripheral surface of the substrate.

  As shown in FIG. 8A, before the step of bringing a part of the outer peripheral surface of the aluminum base material 12 into contact with the first etching solution E1 stored in the first etching tank 51, the outer peripheral surface of the aluminum base material 12 is obtained. Is performed in such a manner that a part of the substrate is brought into contact with the pretreatment etching solution E2 contained in the etching bath 52. After the step of contacting a part of the outer peripheral surface of the aluminum base material 12 with the first etching solution E1 stored in the first etching bath 51, a part of the outer peripheral surface of the aluminum base material 12 was stored in the etching bath 52. A step of contacting with the post-processing etching solution E2 may be performed. The pre-treatment etching solution and / or the post-treatment etching solution can be obtained, for example, by diluting the first etching solution. That is, the concentration of the pre-treatment etching solution and / or the post-treatment etching solution is lower than that of the first etching solution, for example. The pre-treatment etching solution and the post-treatment etching solution are, for example, the same etching solution, but may be different etching solutions.

  With reference to FIG. 9, it will be described that the occurrence of periodic unevenness is suppressed by performing the surface treatment using the pretreatment etching solution. When the surface treatment is not performed with the pretreatment etching solution E2, the first etching solution E1 acts directly on the outer peripheral surface of the aluminum base 12, as shown in FIG. On the other hand, when the surface treatment is performed in advance using the pretreatment etching solution E2 having a low etching rate, the pretreatment etching solution E2 is applied to the outer peripheral surface of the aluminum base 12 as shown in FIG. Acts directly. It is preferable to appropriately adjust the concentration and temperature of the pretreatment etching solution E2 so that the inverted antiglare structure is hardly formed by the pretreatment etching solution E2. For example, the pre-treatment etchant and / or the post-treatment etchant can be obtained by, for example, diluting the first etchant five-fold. An experimental example will be described later on an etching solution suitable for the pretreatment etching solution E2. After that, when the matte processing step using the first etching liquid E1 is performed, as shown in FIG. 9B, the first etching liquid E1 passes through the preprocessing etching liquid E2 attached to the outer peripheral surface of the aluminum base material 12. Acts on the outer peripheral surface of the aluminum base 12. Thereby, when a part of the outer peripheral surface of the aluminum base material 12 is brought into contact with the first etchant E1, the reaction speed of the satin finish treatment with the first etchant E1 is increased at a position where the aluminum base 12 first comes into contact with the first etchant E1. In particular, the phenomenon of becoming large is reduced. 9 (a) and 9 (b) and FIG. 10 (a) which will be described later, the etching liquid adhering to the outer peripheral surface of the aluminum base 12 is schematically shown for simplicity. However, it may be omitted in other drawings.

  When the surface treatment with the post-treatment etching solution E2 is not performed, a washing process with pure water, for example, is performed after the matte treatment process with the first etching solution E1. The concentration of the first etchant and that of pure water are significantly different. That is, since the etching rates with respect to the outer peripheral surface of the aluminum base material 12 are greatly different from each other, direct contact between these at the outer peripheral surface of the aluminum base material 12 may cause unevenness of the inverted anti-glare structure. On the other hand, if the surface treatment with the post-processing etching liquid is performed after the satin finish processing step with the first etching liquid E1, the difference in concentration between the first etching liquid E1 and the post-processing etching liquid is small, The occurrence of unevenness in the anti-glare structure is suppressed.

  The above-mentioned step (II-1) (a step of bringing a part of the outer peripheral surface of the base material into contact with an etching solution for pretreatment before the satin finish processing step) and step (II-2) (after the satin finish processing step, In the step of contacting a part of the outer peripheral surface with the etching solution for post-processing, the aluminum base 12 is preferably rotated about the long axis of the aluminum base 12 as in the step (I). The rotation speed of the aluminum substrate 12 in the above steps (II-1) and (II-2) is, for example, substantially the same as the rotation speed in the step (I).

  There may be a plurality of steps for performing the surface treatment with the pretreatment etching solution. As shown in FIG. 8A, in the method for treating the surface of the base material according to the embodiment of the present invention, before the step of contacting a part of the outer peripheral surface of the aluminum base material 12 with the pretreatment etching solution E2, The method may further include a step of bringing a part of the outer peripheral surface of the base material 12 into contact with the pretreatment etching solution E3 contained in the etching tank 53. The etching rate of the pretreatment etching solution E3 on the outer peripheral surface of the aluminum substrate 12 is lower than the etching rate of the pretreatment etching solution E2 on the outer peripheral surface of the aluminum substrate 12.

  Similarly, a plurality of steps may be performed for the surface treatment with the post-treatment etching solution. After the step of contacting a part of the outer peripheral surface of the aluminum base material 12 with the etching solution E2 for post-processing, a part of the outer peripheral surface of the aluminum base material 12 is brought into contact with the etching solution E3 for the post-processing housed in the etching tank 53. The method may further include the step of performing The etching rate of the post-treatment etching solution E3 on the outer peripheral surface of the aluminum substrate 12 is lower than the etching rate of the post-processing etching solution E2 on the outer peripheral surface of the aluminum substrate 12.

  As shown in FIG. 8B, the pre-treatment etching solution and / or the post-treatment etching solution may be contained in a first etching tank 51 containing a first etching solution E1. In this case, typically, the pre-treatment etching solution and / or the post-treatment etching solution is obtained by lowering the temperature of the first etching solution E1.

  As described above, by gradually changing the etching rate of the etchant in contact with the outer peripheral surface of the aluminum base material 12 with respect to the outer peripheral surface, the inverted anti-glare structure formed on the aluminum base material 12 in the circumferential direction is reduced. Unevenness can be suppressed. For example, by making the change in the concentration of the etchant in contact with the outer peripheral surface of the aluminum base material 12 gentle, it is possible to suppress unevenness in the circumferential direction of the inverted anti-glare structure formed on the aluminum base material 12. .

  Similarly, by making the temperature change of the outer peripheral surface of the aluminum base material 12 gentle, it is possible to suppress unevenness in the circumferential direction of the inverted anti-glare structure formed on the aluminum base material 12. For example, the processing temperature of the first etching liquid and / or the pre-processing etching liquid may be set to be low in order to increase the margin of the matte processing time. At this time, if the temperature of the outer peripheral surface of the aluminum base material 12 to be treated is higher than the temperature of the etching solution, the inverted anti-glare structure formed on the aluminum base material 12 may have macro unevenness. To solve this problem, before the step of contacting a part of the outer peripheral surface of the aluminum substrate 12 with the first etching solution or the pre-treatment etching solution, the outer peripheral surface of the aluminum substrate 12 is cooled to a low temperature (for example, about 10 ° C.). Since the temperature of the outer peripheral surface of the aluminum base material 12 can be reduced by providing the step of spraying pure water, unevenness can be suppressed. The step of spraying low-temperature pure water is performed by, for example, a shower method using a nozzle.

  In the surface treatment method of the base material of the comparative example described with reference to FIG. 6A, the problem of unevenness in the circumferential direction of the base material described above hardly occurs. As shown in FIG. 6A, when a moth-eye mold is manufactured using the method of surface treatment of a base material of the comparative example, when the outer peripheral surface of the aluminum base material 12 is brought into contact with the first etchant E <b> 1, The position in contact with the first etchant E1 is the bottom surface of the aluminum base 12. When the anti-reflection film 32 is manufactured using a moth-eye mold, linear unevenness appears at the end of the anti-reflection film 32 (dashed line in FIG. 6B). Is easy. Further, no periodic unevenness appears on the antireflection film 32. In some cases, unevenness may occur in the direction corresponding to the long axis direction of the moth-eye mold (the long axis direction of the aluminum base 12). For example, the unevenness may be caused by etching the aluminum base 12 in the etching bath 91. If it can be completely immersed within 3 seconds, it can be suppressed. However, as described above, the surface treatment method for the base material of the comparative example is inferior to the surface treatment method for the base material according to the embodiment of the present invention in that the cost for the etching solution and the installation location of the etching bath increase. . In particular, when the length H and / or the diameter D in the major axis direction of the base material is large, there is a problem that the cost for the etching solution and the installation place of the etching bath in the surface treatment method for the base material of the comparative example increase. Become noticeable.

[Long axis direction unevenness of substrate]
As shown in FIG. 10B, the aluminum base material 12 that has been subjected to the satin finish treatment by the base material surface treatment method according to the embodiment of the present invention has an aluminum base material 12 In some cases, a plurality of streak-like irregularities extending in a direction substantially perpendicular to the long axis direction may occur. The streak-like unevenness was also visually recognized on the antireflection film 32 manufactured using the moth-eye mold. The present inventor has conceived of a method of spraying an etching solution for a satin finish on the outer peripheral surface of the aluminum substrate 12 in order to suppress the occurrence of streak-like unevenness.

  This will be described with reference to FIGS. FIG. 10A is a schematic diagram for explaining the method for treating the surface of the base material according to the embodiment of the present invention. FIG. 10B is a schematic diagram for explaining a plurality of stripe-like irregularities that occur on the outer peripheral surface of the aluminum base 12 and extend in a direction substantially perpendicular to the long axis direction of the aluminum base 12. FIGS. 10C and 10D are schematic diagrams for explaining the angle θ at which the spray etching liquid is jetted.

  As shown in FIG. 10A, in a certain embodiment, the surface treatment method for a base material according to the embodiment of the present invention employs a fourth etching solution (hereinafter referred to as a spraying etching solution) that is the same as the first etching solution E1. The method further includes a step (III) of spraying E4 onto the outer peripheral surface of the aluminum substrate 12.

  In the step (III) of spraying the spraying etching solution E4 onto the outer peripheral surface of the aluminum base material 12, for example, a part of the outer peripheral surface of the aluminum base material 12 is brought into contact with the first etching solution E1 stored in the first etching tank 51. Simultaneously with the step (step (II)), the spraying etchant E4 is sprayed on the outer peripheral surface of the aluminum base 12 in the vicinity of a portion in contact with the first etchant E1. “Around the outer peripheral surface of the aluminum base material 12 near the portion that is in contact with the first etchant E1” includes the outer peripheral surface of the aluminum base material 12 that is in contact with the first etchant E1. .

  Optical images of the aluminum base 12 are shown in FIGS. FIG. 11A shows an aluminum base material 12 that has been subjected to a satin finish treatment by a surface treatment method that does not include the step (III) (the step of spraying the spraying etching solution onto the outer peripheral surface of the aluminum base material 12). 11 (b) is the aluminum base material 12 that has been subjected to the satin finish treatment by the surface treatment method including the above step (III) (the step of spraying the spraying etching solution onto the outer peripheral surface of the aluminum base material 12). It can be seen that streak-like unevenness appears on the surface of the aluminum base 12 in FIG. 11A, but does not appear on the aluminum base 12 in FIG. 11B.

  It is considered that the streak-like unevenness is caused by the non-uniform thickness of the liquid film of the etching solution on the outer peripheral surface of the aluminum base 12. According to the study of the present inventor, the portion of the outer peripheral surface of the aluminum base material 12 where the thickness of the liquid film of the etching liquid is thin has a high density of the macro convex portions 12p and the thickness of the liquid film of the etching liquid is large. It was confirmed that the density of the macro convex portions 12p tended to be low at the portions. That is, it is considered that the reaction speed of the satin finish is high in a place where the liquid film of the etchant is thin, and the reaction speed of the satin finish is slow in a place where the liquid film of the etchant is thick. When the spraying etching solution E4 is sprayed on the outer peripheral surface of the aluminum base material 12 in the vicinity of a portion in contact with the first etching liquid E1, the thickness of the liquid film on the outer peripheral surface of the aluminum base material 12 becomes uniform. Thus, it is considered that the occurrence of streak-like unevenness can be suppressed.

  In the step (III) of spraying the spraying etching solution E4 onto the outer peripheral surface of the aluminum base material 12, for example, the base material is arranged such that the major axis direction of the base material is substantially parallel to the horizontal direction. This is performed simultaneously with the step of rotating the base material around the long axis (the above step (I)), and the spraying etching solution E4 contacts the first etching solution E1 in the outer peripheral surface of the aluminum base material 12. Is sprayed to the vicinity of the location where the rotating part is located away from the first etching solution E1 contained in the first etching tank 51 in the above step (I).

  The step (III) of spraying the spray etching liquid E4 onto the outer peripheral surface of the aluminum base 12 is performed using, for example, a spray nozzle. As the spray nozzle, for example, a fan-shaped one-fluid nozzle (for example, HB1 / 4VV-SS11004 manufactured by Spraying Systems) can be used. A plurality of spray nozzles may be arranged side by side along the long axis direction of the aluminum base 12. By using a plurality of spray nozzles, it is possible to uniformly spray the spraying etching solution E4 on a portion of the outer peripheral surface of the aluminum base 12 which is in contact with the first etching solution E1. For example, in the surface treatment of the aluminum base material 12 whose length H in the major axis direction is 1.6 m, the spraying etching solution E4 may be sprayed using 16 spray nozzles.

  The flow rate of the spraying etchant E4 sprayed from each spray nozzle is, for example, 1.0 L / min, and preferably 0.6 L / min to 1.2 L / min. The pump can be appropriately selected from known pumps and used according to the flow rate and the pressure of the spraying etching solution E4. For example, CHI2-30AWGBUBV manufactured by Grundfos can be used.

  In the step (III) of spraying the spraying etching solution E4 onto the outer peripheral surface of the aluminum base 12, the angle θ at which the spraying etching solution E4 is sprayed is, for example, inclined from 45 ° to less than 90 ° from the vertical direction. As shown in FIG. 10C, the inclination angle with respect to the horizontal direction, that is, the inclination angle with respect to the surface of the first etching liquid E <b> 1 stored in the first etching tank 51 is 90 ° -θ. If the angle θ is less than 45 °, the inclination angle (90 ° −θ) with respect to the surface of the first etching solution E1 contained in the first etching bath 51 is large, so that the spraying etching solution E4 is There was a case where the surface of the first etching liquid E <b> 1 contained in the substrate 51 bounced off and adhered to the surface of the aluminum base material 12. As shown in FIG. 10D, when the angle θ is 90 ° or more, the spraying etchant E4 sometimes bounces off the surface of the aluminum base material 12 and scatters. If the angle θ is 90 ° or more, the effect of making the thickness of the liquid film on the outer peripheral surface of the aluminum base 12 uniform may not be obtained.

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

[Composition of etching solution for satin finish]
The satin finish process was performed by changing the composition of the etching solution for the satin finish.

  As shown in Table 1 below, Experimental Examples 1-1, 2-1 and 3-1 were prepared using ammonium fluoride, ammonium sulfate and dihydrogen phosphate in an etching solution for satin finish treatment. With the ammonium ratio fixed at 5: 2: 2, these concentrations were changed, and a small piece (5 cm × 2 cm) of the aluminum substrate was subjected to a satin finish process. As shown in Table 1, the etching solution for the satin finish used in Experimental Example 1-1 contains ammonium fluoride, ammonium sulfate, and ammonium dihydrogen phosphate at 5 mass%, 2 mass%, and 2 mass%, respectively. The etching solutions for the satin finish used in Experimental Examples 2-1 to 4-1 were respectively diluted two to three times and five times the etching solutions used in Experimental Example 1-1. .

As the aluminum substrate, an Al-Mg-Si-based aluminum alloy formed from JIS A6063 was used. 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, and others: 0.05% or less individually, 0.15% or less as a whole, balance: Al

  The aluminum substrate (JIS A6063) was formed by hot extrusion using indirect extrusion (mandrel method), subjected to cold drawing, and then subjected to mirror finishing by cutting with a cutting tool. Before the satin finish treatment step, an alkali washing step was performed on the aluminum base material. As the alkaline etching solution, an aqueous solution containing an organic alkaline cleaning agent (product name: Semiclean LC-2, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 8 mass% was used. Semi Clean LC-2 manufactured by Yokohama Yushi Kogyo Co., Ltd. contains the following composition: 2-aminoethanol (12 mass%), chelating agent (2 mass% to 6 mass%), surfactant (2 mass% to 6 mass%). The aluminum substrate was immersed in an alkaline etching solution at 40 ° C. for 30 minutes (alkali washing step). Thereafter, the aluminum substrate was rinsed with water by immersing it in pure water, and then immersed in an etching solution (temperature: 10 ° C.) for the satin finish process for a predetermined period of time without washing and drying (the satin finish process). Thereafter, the aluminum substrate was washed with water by immersing it in pure water and dried by air blow.

  Anti-glare films were formed on Experimental Examples 1-1 to 4-1 using the respective aluminum substrates as molds. The anti-glare film is formed by applying a release agent (Optool DSX manufactured by Daikin Industries, Ltd.) to the surface of an aluminum base material, then applying a urethane acrylate-based ultraviolet curable resin, and irradiating ultraviolet rays in a state of being transferred onto a TAC film. And cured. Such a film having no moth-eye structure and having only an anti-glare structure like the sample film used here may be called an anti-glare film.

  Table 1 shows the results of evaluating the anti-glare function using the aluminum substrate of Experimental Examples 1-1 to 4-1 and the anti-glare film (sample film) obtained from the aluminum substrate. FIGS. 12A to 12D show optical microscopes when observing the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 1-1 to 4-1 from a vertical direction. 12 (e) to 12 (h) show SEM images when the surface of the antiglare film formed from the aluminum base material of Experimental Examples 1-1 to 4-1 was observed from the vertical direction. (20 μm full scale in SEM image). The optical microscope image was obtained using an optical microscope (manufactured by Olympus Corporation, product name: BH2-UCB (BX-16)). The same applies to the following optical microscope images. The SEM image was obtained using a field emission scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name: S-4700). The same applies to the following SEM images.

  The “macro convex portion 12p” in Table 1 indicates the two-dimensional size (area circle equivalent diameter) when viewed from the normal direction of the surface of the macro convex portion 12p formed on the aluminum base material 12. , Values estimated from optical microscope images.

  "Haze value" in Table 1 shows the result of measuring the haze value of the anti-glare 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.

  "Anti-glare property" in Table 1 means that the anti-glare film was formed by using a liquid crystal television (AQUAS LC-UD1, type 60, manufactured by Sharp Corporation, dot pitch in the row direction: about 115 μm, dot pitch in the column direction: about 345 μm). This is a result of judging the presence or absence of anti-glare properties by sticking to the surface of a display panel and visually observing the reflection of a fluorescent lamp. In Table 1, “○” indicates that it was determined that there was antiglare, and “x” indicates that it was determined that there was no antiglare. Generally, an anti-glare film having a large haze value has an excellent anti-glare function and an excellent anti-glare property.

  "Glittering" in Table 1 indicates that the anti-glare film is a display of a liquid crystal television (AQUAS LC-UD1, type 60, manufactured by Sharp Corporation, dot pitch in the row direction: about 115 μm, dot pitch in the column direction: about 345 μm). This is the result of affixing to the surface of the panel, performing green display on the entire surface, and asking whether or not glare is visible in the image passing through the film. Interviews were conducted with five people. In Table 1, "○" indicates "no glare", indicating that 0 out of 5 people answered "glare", and "△" indicates one person. It indicates that the number is three or less, and "x" indicates that the number is four or more.

The glare is a phenomenon in which the display panel appears to be glare as a whole, and particularly tends to be noticeable when a green display is performed on the entire surface. The glare is caused by the average distance between adjacent macro-projections 12p (see AD _int in FIG. 1C), the row-direction dot pitch Px (see FIG. 22) and / or the column-direction dot pitch Py of the display panel. It is considered that the above relationship causes the anti-glare structure formed on the anti-glare film and the dots of the display panel to interfere with each other. The glare may also occur when the average distance between adjacent macro-projections 12p is smaller than the dot pitch. The glare tends to be suppressed when the average distance between adjacent macro-projections 12p and the two-dimensional size of the macro-projections 12p are sufficiently smaller than the dot pitch.

  As can be seen from Table 1 and FIG. 12, the size of the macro convex portion 12p formed on the aluminum base 12 changes depending on the concentration of the etching solution for the satin finish. The anti-glare film obtained in Experimental Example 1-1 has excellent anti-glare properties and can suppress glare. In Experimental Example 2-1 using an etching solution obtained by diluting the etching solution of Experimental Example 1-1 by two times, the two-dimensional size (about 15 μm) of the macro convex portion 12p is different from that in Experimental Example 1-1. (Approximately 10 μm), and in the experimental example 3-1 using an etchant obtained by diluting the etchant of the experimental example 1-1 three times, the two-dimensional size of the macro convex portion 12p is even larger. (About 20 μm). The anti-glare film of Experimental Example 2-1 was inferior to the anti-glare film of Experimental Example 1-1 from the viewpoint of suppressing glare, and the anti-glare film of Experimental Example 3-1 could not suppress glare. .

  On the other hand, in Experimental Example 4-1 using the etchant obtained by diluting the etchant of Experimental Example 1-1 by 5 times, no macro convex portion 12p was formed on the surface of the aluminum base 12 (FIG. 12). (D)). As a result, the anti-glare film of Experimental Example 4-1 did not have anti-glare properties. The black spots in the optical microscope image of FIG. 12D indicate galvanic corrosion generated by the alkaline cleaning step. Galvanic corrosion occurring in the alkaline cleaning step will be described later.

  Since the etchant used in Experimental Example 4-1 does not form the macro convex portion 12p on the surface of the aluminum base 12, it is suitably used as a pretreatment etchant and / or a post-treatment etchant.

  Experimental Example 1-2, Experimental Example 1-3, Experimental Example 2-2, Experimental Example 3-2, and Experimental Example 4-2 shown in Table 2 are different from the experimental example in Table 1 in the time of satin finish. Other experimental conditions and evaluation procedures are the same as those described for Table 1.

  Using the aluminum substrate of Example 1-2, Example 1-3, Example 2-2, Example 3-2, and Example 4-2 and the antiglare film (sample film) obtained from the aluminum substrate. Table 2 shows the results of evaluating the anti-glare function. FIGS. 13 (a) to 13 (e) show inverted examples formed by the satin finish processing steps of Experimental Example 1-2, Experimental Example 1-3, Experimental Example 2-2, Experimental Example 3-2 and Experimental Example 4-2. The optical microscope image (50 times) when observing the surface of the aluminum base material which has an anti-glare structure from a perpendicular direction is shown.

  Comparing Table 1 and Table 2, it can be seen that the evaluation results of the glare and antiglare property of the antiglare film did not change depending on the time of the satin finish treatment. It can be seen that the concentration of the etching solution for the satin finish treatment greatly contributes to the glare and the antiglare property of the antiglare film. Further, the etching solution used in the experimental example 4-2 does not form the macro convex portion 12p on the surface of the aluminum base 12 like the etching solution used in the experimental example 4-1. It is suitably used as a liquid and / or an etching liquid for post-treatment.

  Subsequently, as shown in Table 3, an experiment was performed by changing the ratio of ammonium fluoride, ammonium sulfate, and ammonium dihydrogen phosphate in the etching solution for the satin finish from 5: 2: 2. In Experimental Examples 5-1 to 5-4, the proportion of any of ammonium fluoride, ammonium sulfate, and ammonium dihydrogen phosphate was changed from the composition of the etching solution for the satin finish used in Experimental Example 1-1. Things. In Experimental Examples 6-1 and 6-2, the proportion of any one of ammonium fluoride, ammonium sulfate, and ammonium dihydrogen phosphate was changed from the composition of the etching solution for the satin finish used in Experimental Example 2-1. Things. The experimental conditions and evaluation procedure are basically the same as those described for Table 1. However, the time of the satin finish is different from that of Table 1.

  Table 3 shows the results of evaluating the anti-glare function using the aluminum base material of Experimental Examples 5-1 to 5-4 and Experimental Examples 6-1 to 6-2 and the anti-glare film (sample film) obtained from the aluminum base material. Shown in FIGS. 14A to 14D show optical microscopes when observing the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 5-1 to 5-4 from a vertical direction. FIGS. 14E and 14F show SEM images when the surface of the antiglare film formed from the aluminum base material of Experimental Examples 5-3 and 5-4 was observed from the vertical direction. (20 μm full scale in SEM image). FIGS. 15A and 15B show an optical microscope when the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 6-1 and 6-2 is observed from a vertical direction. An image (50x) is shown.

  By comparing the results of Experimental Example 5-3 (Table 3 and FIG. 14) with the results of Experimental Example 1-1, when the content of ammonium fluoride was reduced, the value of the haze value of the antiglare film was reduced, and It can be seen that the two-dimensional size of the macro convex portion 12p formed on the base material 12 tends to increase. This tendency is the same as when the etching solution of Experimental Example 1-1 was diluted twice (Experimental Example 2-1). In Experimental Example 5-4, when the content of ammonium fluoride was further reduced, as in the case of diluting the etching solution of Experimental Example 1-1 by 5 times (Experimental Example 4-1), macro convex portions 12p were formed. Not formed.

  As in Experimental Example 5-2 and Experimental Example 6-1, an antiglare film having antiglare properties and capable of suppressing glare can be produced even with an etching solution containing no ammonium dihydrogen phosphate. did it. Experimental example 5-2 has a longer satin finish time than Experimental example 1-1 (sashimi processing time: 2 minutes), and experimental example 6-1 has experimental example 2-1 (sashimi processing time: 2). Since the matte processing time is longer than that of (min), the use of an etchant not containing ammonium dihydrogen phosphate can provide an advantage that the time margin of matte processing can be increased. However, since ammonium dihydrogen phosphate has the effect of suppressing unevenness of the satin finish, the etching solution preferably contains ammonium dihydrogen phosphate. Further, in the case of an etching solution containing no ammonium dihydrogen phosphate, bubbles were sometimes generated in the satin finish treatment step. In order to suppress unevenness of the satin finish due to generation of bubbles, it may be preferable to appropriately add an antifoaming agent.

  As in Experimental Example 5-1 and Experimental Example 6-2, when the etchant containing no ammonium sulfate is used, the two-dimensional size of the macro convex portion 12p is larger than when an etchant containing ammonium sulfate is used. Tended to increase. That is, the two-dimensional size of the macro convex portion 12p formed on the aluminum base material of Experimental Example 5-1 is larger than that of Experimental Example 1-1, and is formed on the aluminum base material of Experimental Example 6-2. The two-dimensional size of the obtained macro convex portion 12p was larger than that of Experimental Example 2-1. The anti-glare film of Experimental Example 5-1 is inferior to the anti-glare film of Experimental Example 1-1 in terms of suppressing glare. The anti-glare film of Experimental Example 6-2 could not suppress glare.

[Composition of alkaline etching solution for alkaline cleaning step]
First, the effect of the alkaline cleaning step using an alkaline etching solution was examined.

  The cleaning step was performed with an acidic cleaning liquid, a neutral cleaning liquid, and an alkaline cleaning liquid (also referred to as an alkaline etching liquid) before the satin finish processing step while changing the conditions as shown in Table 4 below. As the acidic cleaning liquid, an aqueous solution containing an acidic cleaning agent (product name: Scale Cut P, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 3 mass% was used. Scale Cut P manufactured by Yokohama Yushi Kogyo Co., Ltd. contains citric acid as an acid in an amount of 5 mass% to 15 mass%. As the neutral cleaning solution, an aqueous solution containing a neutral cleaning agent (manufactured by Sanwa Yuka Kogyo Co., Ltd., product name: Sunclean HS) at a concentration of 3 mass% is used. As the alkaline etching solution, an organic alkaline cleaning agent is used. An aqueous solution containing (Yokohama Yushi Kogyo Co., Ltd., product name: Semiclean LC-2) at a concentration of 8 mass% was used.

  As the etching solution for the satin finish, the same etchant as the satin finish used in Experimental Example 1-1 was used. That is, they contain 5 mass%, 2 mass% and 2 mass% of ammonium fluoride, ammonium sulfate and ammonium dihydrogen phosphate, respectively. The small pieces of the aluminum substrate used are the same as those described for Table 1.

  It was confirmed that the surface of the aluminum substrate after washing with the acidic, neutral and alkaline washing liquids had hydrophilicity. Specular reflectivity was confirmed on the surface of the aluminum substrate after washing with an acidic and neutral washing solution. On the surface of the aluminum substrate after washing with the alkaline washing solution, diffuse reflection (including scattering) was confirmed in addition to specular reflection. In Table 4, regarding "cutting marks", "x" indicates that cutting marks were formed, and "o" indicates that no cutting marks were formed. In Table 4, “x” indicates that the crystal grains were conspicuous, and “o” indicates that almost no crystal grains were observed. No cutting marks were formed on the surface of the aluminum base material subjected to the satin finish treatment step after the washing step was performed with the alkaline washing liquid, and no crystal grains were confirmed. Cutting marks were formed on the surface of the aluminum base material which was subjected to the satin finish treatment step after the washing step with the acidic and neutral washing liquid. Almost no crystal grains were found on the surface of the aluminum base material that had been subjected to the satin finish process after the washing process with the neutral cleaning solution, but the satin finish process was performed after the washing process with the acidic washing solution. Crystal grains were conspicuous on the surface of the aluminum substrate. When crystal grains are conspicuous on the surface of the aluminum base material, the image through the film looks whitish when the anti-glare film is attached to the display panel surface and observed from an angle inclined from the normal direction of the anti-glare film. There is.

  From the results in Table 4, it is preferable to use an alkaline etching solution in the cleaning step before the satin finish processing step. By performing the alkali cleaning step using an alkaline etchant before the satin finish step, formation of cutting marks could be suppressed. When a neutral cleaning liquid was used, formation of cutting marks could not be suppressed. It has been found that when an acidic cleaning liquid is used, formation of cutting marks cannot be suppressed, and crystal grains (grain boundaries) of the aluminum base material are further conspicuous.

  In the experimental examples in this specification, the alkaline etching solution and the etching solution for the satin finish treatment were all prepared on the day of performing the alkali cleaning step or the satin finished process. According to the study by the present inventors, a significant difference may appear in the obtained inverted antiglare structure between the etching solution prepared on the day and the etching solution prepared one week ago.

  As shown in Table 4, by performing the alkali cleaning step using an alkaline etching solution before the satin finish step, formation of cutting marks could be suppressed. It is considered that at least a part of the work-affected layer of the aluminum base material that could cause cutting marks could be removed by the alkaline etchant. However, according to the study of the present inventors, the following problems may occur depending on the type of the alkaline etching solution.

  Generally, it is considered that the thicker the work-affected layer removed from the surface of the aluminum base material 12, the more the formation of cutting marks is suppressed. For example, by immersing the aluminum base 12 in an alkaline etching solution for a long time, the work-affected layer removed from the surface of the aluminum base 12 can be thickened. However, since the oxide film on the surface of the aluminum substrate 12 is removed by the alkaline etching solution, galvanic corrosion proceeds on the surface from which the oxide film has been removed, and as a result, a large number of concave portions (pit corrosion) are formed. You. Note that galvanic corrosion occurs between Ti and Al contained in the aluminum base material 12.

  First, in order to examine the formation of a concave portion due to galvanic corrosion, only an alkali cleaning step was performed on an aluminum substrate under the conditions shown in Table 5. As the alkaline etching solution, an aqueous solution containing an organic alkaline cleaning agent (product name: Semiclean LC-2, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 8 mass% was used. The small pieces of the aluminum substrate used are the same as those described for Table 1. Using each aluminum substrate as a mold, a polymer film was produced in the same manner as described in Table 1. The measurement of the haze value was also performed in the same manner as described in Table 1. FIG. 16 (a) shows an optical microscope image (magnification: 50) of the surface of the aluminum substrate subjected to the alkali washing step of Experimental Example 7-1 when observed from a vertical direction, and FIGS. c) shows an SEM image (20 μm full scale in the SEM image) of the surface of the polymer film formed from the aluminum base material of Experimental Examples 7-1 and 7-2 when observed from the vertical direction.

  As shown in Table 5 and FIG. 16, when the time of the alkali cleaning step becomes longer, the appearance of the projections formed on the surface of the polymer film corresponding to the depressions caused by galvanic corrosion formed on the aluminum base material. It was confirmed (see FIG. 16 (c)).

  Next, an alkali cleaning step and a satin finish step were performed on the aluminum substrate under the conditions shown in Table 6. The small pieces of the aluminum substrate used are the same as those described for Table 1. FIGS. 17A to 17D show optical microscopes when observing the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 8-1 to 8-4 from a vertical direction. 17 (e) to 17 (h) show SEMs when the surface of the polymer film formed from the aluminum base material of Experimental Examples 8-1 to 8-4 was observed from the vertical direction. An image (full scale 20 μm in the SEM image) is shown.

  In Examples 8-1 to 8-4, an aqueous solution containing an organic alkaline cleaning agent (product name: Semiclean LC-2, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 12 mass% was used as the alkaline etching solution. As the etchant for the satin finish, a solution obtained by diluting the etchant for the satin finish used in Experimental Example 1-1 twice was used. In the following table, “1 ×” or “2x dilution” of the etchant for the satin finish is based on the etchant for the satin finish used in Experimental Example 1-1. Other experimental conditions and evaluation procedures are the same as those described for Table 1. In Table 6, regarding "cutting marks", "x" indicates that cutting marks were formed on the surface of the aluminum base material, and "o" indicates that no cutting marks were formed. In Table 6, “Galvanic corrosion” indicates “」 ”when no concave portion due to galvanic corrosion was formed,“ △ ”when a concave portion due to galvanic corrosion was formed but this was not practically problematic, and“ Galvanic corrosion ”. When a concave portion is formed to the extent that it becomes a problem in practical use, the result is evaluated as “x”. "Mass change" in Table 6 is a result of measuring a change in mass of the aluminum base material before and after the alkali cleaning step.

  As shown in Table 6 and FIG. 17, when the alkali cleaning step was performed for 40 minutes or more (Experimental Examples 8-2 to 8-4), no cutting marks were formed. On the other hand, when the time of the alkali cleaning step becomes longer, a concave portion due to galvanic corrosion is formed on the surface of the aluminum base material (a black portion in the optical microscope image in FIG. 17), and a convex portion is formed in the anti-glare film. You can check. In particular, when the alkaline cleaning step is performed for 60 minutes or more (Experimental Examples 8-3 and 8-4), it can be confirmed that the density of these is increased.

  When a concave portion due to galvanic corrosion occurs on the surface of the aluminum substrate 12, a concave portion also occurs on the surface of the moth-eye mold using the aluminum substrate 12. When a concave portion is formed on the surface of the moth-eye mold due to galvanic corrosion, there is a concern about resin clogging and deterioration of transferability. Further, in the antireflection film manufactured using the moth-eye mold, a convex portion corresponding to the concave portion due to galvanic corrosion may be formed. Such an antireflection film may be inferior in suppression of glare and in scratch resistance. Further, since it is difficult to control the position where the galvanic corrosion occurs in the aluminum base material 12, it may be difficult to control the haze value of the antireflection film.

  The present inventor has conceived a method for removing at least a part of a work-affected layer of an aluminum base material while suppressing generation of a concave portion due to galvanic corrosion in order to solve the above problem.

  Under the conditions shown in Table 7 below, the aluminum substrate was subjected to an alkali washing step and a satin finish step. In Experimental Example 9-1, an aqueous solution containing an organic alkaline cleaning agent (product name: Semiclean LC-2, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 8 mass% was used as the alkaline etching solution. The alkaline etching solution in Experimental Examples 9-2 to 9-4 was obtained by adding 5 vol% of a corrosion inhibitor (Kiresbit AL, manufactured by Kyrest Co., Ltd.) as an acidic additive to the alkaline etching solution in Experimental Example 9-1. Things. Thereby, the pH of the alkaline etching solution of Experimental Examples 9-2 to 9-4 is lower than the pH of the alkaline etching solution of Experimental Example 9-1. Other experimental conditions are the same as in Table 6.

  FIGS. 18A to 18D show optical microscopes when observing the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 9-1 to 9-4 from a vertical direction. An image (50x) is shown.

  18 (b) to 18 (d) and FIG. 18 (a), it can be seen that the formation of the concave portions due to galvanic corrosion is effectively suppressed. In addition, from Table 7, it is considered that the effect of removing the work-affected layer is the same between Experimental Example 9-1 and Experimental Example 9-2 since there is no difference in the mass change of the aluminum base material in the alkali cleaning step. be able to. That is, by adding an acidic additive to the alkaline etching solution, the formation of a concave portion due to galvanic corrosion could be suppressed while the formation of cutting marks was suppressed.

The addition of the acidic additive to the alkaline etchant lowers the pH of the alkaline etchant. That is, in Examples 9-2 to 9-4, the effect of etching the surface of the aluminum base material is considered to be weaker than in Example 9-1. On the other hand, in Experimental Examples 9-2 to 9-4, ionization (Al (OH) ₄ ⁻ ) is less likely than in Experimental Example 9-1, and aluminum hydroxide (Al (OH) ₃ ) is easily formed. It is considered that the formation of the concave portion due to galvanic corrosion was suppressed by the formation of aluminum hydroxide on the surface of the aluminum substrate.

  The acidic additive is not limited to those exemplified above, and it is considered that any acidic additive can be used as long as it is soluble in an alkaline etching solution and has no corrosiveness to aluminum. The corrosion inhibitor (Kiresvit AL) used as an acidic additive in the experimental examples is usually used by adding a few percent. On the other hand, in the present application, by adding 5 mass% to 10 mass% (see Table 8), it is possible to obtain an alkaline etching solution that suppresses formation of concave portions due to galvanic corrosion while suppressing formation of cutting marks. Was.

  In addition, in FIGS. 18 (b) to 18 (d), deposits can be confirmed on the surface of the aluminum base material. This is considered to be a deposit called smut. Smut may be formed when aluminum is subjected to alkali etching, and is thought to be formed by impurities and alloy components such as Si, Mg, Fe, and Cu contained in aluminum being precipitated on aluminum. Has been. Smut can be removed with an acidic aqueous solution.

  In order to investigate the optimum composition of the alkaline etching solution, the same experiment as in Table 7 was performed using the conditions in Table 8. FIGS. 19A to 19D show optical microscopes when observing the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 10-1 to 10-4 from a vertical direction. FIGS. 19 (e) to 19 (h) show SEM images when the surface of the polymer film formed from the aluminum base material of Experimental Examples 10-1 to 10-4 was observed from the vertical direction. An image (full scale 20 μm in the SEM image) is shown.

  As can be seen from Table 8 and FIG. 19, among Experimental Examples 10-1 to 10-4, the most effective in Experimental Example 10-2 was to suppress the formation of cutting marks and to form concave portions due to galvanic corrosion. Formation could be suppressed.

  By adding an acidic additive to the alkaline etching solution, the advantage that the time margin of the alkaline cleaning step can be increased is also obtained. FIG. 20A shows the relationship between the time of the alkali cleaning step and the rate of change in mass of the aluminum substrate. FIG. 20B shows the relationship between the time of the alkali cleaning step and the haze value of the antiglare film obtained using the aluminum base as a mold.

  The horizontal axes in FIGS. 20A and 20B indicate the time (minutes) of the alkaline cleaning step. The vertical axis of FIG. 20 (a) is the rate of change in the mass of the aluminum base material before and after the alkali cleaning step, that is, (mass before the alkali cleaning step−mass after the alkali cleaning step) / mass before the alkali cleaning × 100. (%). The vertical axis of FIG. 20B indicates the haze value of the anti-glare film. In FIGS. 20A and 20B, an aqueous solution containing an organic alkaline cleaning agent (product name: Semiclean LC-2, manufactured by Yokohama Yushi Kogyo Co., Ltd.) at a concentration of 12 mass% is used as an alkaline etching solution. Examples 8-1 to 8-4, and acidic addition to an aqueous solution containing an organic alkaline cleaner (Yokohama Yushi Kogyo Co., Ltd., product name: Semiclean LC-2) at a concentration of 16 mass% as an alkaline etching solution. Examples 10-1 to 10-4 using an aqueous solution to which 10 vol% of a corrosion inhibitor (Kiresbit AL, manufactured by Kyrest Co., Ltd.) was added as an agent, and an organic alkaline cleaning agent (Yokohama Yushi Kogyo Co., Ltd.) The results from Experimental Example 11-1 (see Table 9) using an aqueous solution containing Semiclean LC-2) at a concentration of 8 mass% It is door.

  From FIG. 20 (a), for example, the time required to reduce the mass of the aluminum base material by 0.04% depends on the concentration of the organic alkaline cleaning agent (Yokohama Yushi Kogyo Co., Ltd., product name: Semiclean LC-2). When an aqueous solution containing 12 mass% is used (Experimental Examples 8-1 to 8-4), it takes about 20 minutes, whereas an organic alkaline detergent (Yokohama Yushi Kogyo Co., Ltd., product name: Semiclean LC-2) is used. When an aqueous solution containing 10 vol% of a corrosion inhibitor (Kirethbit AL, manufactured by Kyrest Co., Ltd.) as an acidic additive is used in an aqueous solution containing a concentration of 16 mass% (Experimental Examples 10-1 to 10-4), and at least three times the amount You can see that there is. It can be seen that by adding an acidic additive to the alkaline etching solution, the alkali cleaning step can take a long time.

  The acidic additive may be added to the etching solution for the satin finish. The same experiment as in Table 7 was performed using the conditions in Table 9 below. In Experimental Example 11-1, the same etching solution as that used in Experimental Example 1-1 was used as the etching solution for the satin finish treatment. In Experimental Example 11-2, an etchant for the satin finish treatment of Experimental Example 11-1 to which 10 vol% of a corrosion inhibitor (Kiresbit AL, manufactured by Kyrest Co., Ltd.) was added as an acidic additive was used for the satin finish treatment. Used as an etching solution for this purpose.

  FIGS. 21A and 21B show an optical microscope when the surface of an aluminum substrate having an inverted antiglare structure formed by the satin finish process of Experimental Examples 11-1 and 11-2 is observed from a vertical direction. 21 (c) and (d) show SEM when the surface of the polymer film formed from the aluminum base material of Experimental Examples 11-1 and 11-2 was observed from the vertical direction. An image (full scale 20 μm in the SEM image) is shown.

  From Table 9 and FIG. 21, it can be seen that when an acidic additive was added to the etching solution for the satin finish treatment, formation of the concave portion due to galvanic corrosion was suppressed. With the addition of the acidic additive, the texture of the inverted antiglare structure also appears to be slightly coarse.

  The effects of the etching solution and the alkaline etching solution for the satin finish described above are not obtained only in the method for manufacturing the cylindrical moth-eye mold according to the embodiment of the present invention. Since the effects of the etching solution and the alkaline etching solution for the matte finish described above do not depend on the shape of the mold, for example, in the method of manufacturing a plate-shaped (plate-shaped) moth-eye mold, Similar effects can be obtained by using an etchant and an alkaline etchant.

  By using the thus obtained matte-treated cylindrical aluminum substrate to form an inverted moth-eye structure as described above, a moth-eye that can provide an anti-reflection function and an anti-glare function is provided. 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 (TAC film or PET film) on which the antireflection film is formed and the antireflection film, it is preferable to go through the following steps.

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

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

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

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

  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 include a solvent in the ultraviolet curable resin for forming the antireflection film.

  When a PET film is used, 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 include a solvent in the ultraviolet curable resin for forming the antireflection film.

  The method for treating the surface of a substrate according to the present invention is used in a method for producing a mold used for forming an antireflection film (antireflection surface) or the like. The method for producing a mold according to the present invention is used for producing a mold suitably used for forming an antireflection film (antireflection surface) and the like. The antireflection film manufactured using the mold manufactured by the method for manufacturing a mold according to the present invention has a surface structure exhibiting an appropriate antiglare function and an excellent antireflection function, for example, a high-definition display. It is suitably used for panels.

DESCRIPTION OF SYMBOLS 10 Type base material 12 Aluminum base material 14 Porous alumina layer 14p Micro recess 16 Inorganic material layer 18 Aluminum film 18r Aluminum remaining layer 100 Moth-eye mold

Claims (20)

A method for treating the surface of a cylindrical or cylindrical substrate,
In a state where the long axis direction before Kimotozai placed the said substrate so as to be horizontal and substantially parallel to the central long axis of the substrate, and step (a) rotating said substrate,
And step (b) contacting the first etching solution contained a portion of the outer peripheral surface of the front Kimoto material first etching bath,
(C) spraying a second etchant that is the same as the first etchant on the outer peripheral surface of the base material;
Contacting a part of the outer peripheral surface of the base material with a third etchant different from the first etchant before the step (b);
, And
A method for treating a surface of a substrate , wherein an etching rate of the third etching solution on an outer peripheral surface of the substrate is lower than an etching rate of the first etching solution on an outer peripheral surface of the substrate. Wherein step (c), the step (b) simultaneously performed, the second etchant, among outer peripheral surface of the base material, Keru with blown in the vicinity of a portion in contact with said first etchant comprising the step, the surface treatment method of a substrate according to claim 1. Wherein step (c), the performed simultaneously with step (a), the said second etchant, among outer peripheral surface of the substrate, a near portion in contact with the first etchant, the surface treatment method of the step including rotating to Keru with blown in place and step away from the first etchant (a), the substrate according to claim 1 or 2. The surface treatment method for a substrate according to any one of claims 1 to 3 , wherein in the step (c), an angle at which the second etchant is jetted is inclined from 45 ° to less than 90 ° from a vertical direction. . The surface treatment method for a substrate according to any one of claims 1 to 4 , wherein the substrate is an aluminum substrate formed of an Al-Mg-Si-based aluminum alloy and mechanically mirror-finished. . Wherein the first etchant is an aqueous solution containing a salt of hydrogen fluoride and ammonium, surface treatment method of a substrate according to any one of claims 1 to 5. The surface treatment method for a substrate according to claim 6 , wherein the salt of hydrogen fluoride and ammonium is ammonium fluoride. The third etchant, the first an etching solution etching solution obtained by diluting the surface treatment method of a substrate according to any one of claims 1 to 7. The third etchant than said first etchant is cold, the surface treatment method of a substrate according to any of claims 1 to 8. The method according to any one of claims 1 to 9 , wherein the third etching liquid is contained in a second etching tank different from the first etching tank. The third etchant, the first is housed in the etching bath, the surface treatment method of a substrate according to any one of claims 1 to 9. After the step (b), the method further includes a step (b2) of bringing a part of the outer peripheral surface of the base material into contact with a fourth etchant different from the first etchant,
The etching rate with respect to the outer peripheral surface of the base material of the fourth etchant is lower than the etching rate with respect to the outer peripheral surface of the base material of the first etching solution, the substrate according to any one of claims 1 to 11 Surface treatment method. 13. The method according to claim 12 , wherein the fourth etchant is the same etchant as the third etchant. The surface treatment method for a substrate according to any one of claims 1 to 13 , wherein in the step (a), the peripheral speed of the substrate is more than 0 m / s and 0.03 m / s or less. The method for treating a surface of a substrate according to any one of claims 1 to 14 , wherein in the step (a), the rotation speed of the substrate is more than 0 rpm and 2 rpm or less. (A) a step of preparing a cylindrical aluminum substrate formed of an Al-Mg-Si-based aluminum alloy, the substrate being mechanically mirror-finished;
(B) a step of treating the surface of the aluminum substrate by the surface treatment method according to any one of claims 1 to 15 ;
(C) after the step (B), forming an inorganic material layer on the surface of the aluminum base, and forming an aluminum film on the inorganic material layer to form a mold base; ,
(D) after the step (C), anodizing the surface of the aluminum film to form a porous alumina layer having a plurality of micro concave portions;
(E) after the step (D), contacting the porous alumina layer with an etching solution to enlarge the plurality of micro concave portions of the porous alumina layer;
(F) a step of growing the plurality of micro concave portions by anodizing after the step (E). 17. The method of manufacturing a mold according to claim 16 , further comprising, before the step (B), a step (G) of etching the surface of the aluminum base using an alkaline etchant. The mold manufacturing method according to claim 17 , wherein the pH of the alkaline etching solution is 8 or more and 10 or less. The alkaline etching solution, an aqueous solution containing an organic compound having an amino group are prepared by adding an additive of acidic type method of claim 17 or 18. The mold manufacturing method according to claim 19 , wherein a volume of the acidic additive is 5% or more based on a volume of the aqueous solution containing the organic compound having an amino group.

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