JP2008209540A - Anti-reflective article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection preventing article having excellent reflection preventing properties and design properties. <P>SOLUTION: In the reflection preventing article 10 having a fine projection and recess structure on the surface thereof, a distance between projection parts 13 adjacent to each other in the fine projection and recess structure is equal to or shorter than a wavelength of visible light and a standard deviation of distances between centers of gravity of an optional projection part 13 and the six projection parts adjacent to the optional projection part is 4.0 to 12.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antireflection article.

  At interfaces (surfaces) that come into contact with air, such as various displays, lenses, and show windows, there has been a problem of reduced visibility due to reflection of sunlight, illumination, and the like on the surface. As a method for reducing reflection, there is known a method in which several layers of films having different refractive indexes are laminated so that reflected light on the film surface and reflected light on the interface between the film and the substrate cancel each other due to interference. It has been. These films are usually produced by methods such as sputtering, vapor deposition, and coating. However, in such a method, even if the number of laminated films is increased, there is a limit to the decrease in the reflectance and the wavelength dependency of the reflectance. Further, in order to reduce the number of stacked layers in order to reduce the manufacturing cost, a material having a lower refractive index has been demanded.

  In order to lower the refractive index of the material, it is effective to introduce air into the material by any method. As one of the methods, for example, a method of forming a fine concavo-convex structure on the surface of a film is known. According to this method, since the refractive index of the entire surface layer on which the fine concavo-convex structure is formed is determined by the volume ratio between air and the material forming the fine concavo-convex structure, the refractive index can be significantly reduced. Thus, the reflectance can be reduced even when the number of stacked layers is small.

In addition, an antireflection film has been proposed in which pyramidal convex portions are continuously formed on the entire film in the antireflection film formed on the glass substrate (see, for example, Patent Document 1). As described in Patent Document 1, the antireflection film in which the pyramid-shaped convex portion (fine concavo-convex structure) is formed has a continuously changing cross-sectional area when cut in the film surface direction, and the refractive index of air Since the refractive index gradually increases up to the refractive index of the substrate, it is an effective antireflection means.
By the way, as described above, as a method for forming the fine concavo-convex structure on the substrate surface, the fine concavo-convex structure is transferred using a stamper having a fine concavo-convex structure created by an electron beam lithography method or a laser beam interference method. The method is known. However, the fine concavo-convex structure formed by such a method has a problem that interference color is generated due to light interference because the regularity thereof is too high.

Therefore, in recent years, anodized alumina has attracted attention as a means for forming a fine irregular structure with moderate regularity. For example, a method has been proposed in which a member having an alumina pore structure formed by anodizing aluminum at a predetermined voltage in an electrolyte such as oxalic acid, sulfuric acid, phosphoric acid, etc. is used as a stamper. (For example, refer to Patent Document 2).
On the other hand, as a method for producing an article having a fine concavo-convex structure, a method of forming a hydrophilic film made of an inorganic oxide such as a silicon acid compound on a substrate surface by sputtering (for example, see Patent Document 3), or inorganic fine particles. A method of heating and curing after spin-coating a solution on the surface of soda glass (for example, see Patent Document 4) is known.
JP-A 63-75702 JP 2005-156695 A JP 2001-315247 A JP-A-11-217560

However, in the method described in Patent Document 2, since high-purity aluminum is used for the stamper, the crystal grain boundary is clarified by long-term anodic oxidation, and the stamper-derived object is transferred to the fine uneven structure of the stamper. There existed a problem that a pattern was seen and the designability fell.
Further, an article having a fine concavo-convex structure obtained by the manufacturing methods described in Patent Documents 3 and 4 has a problem that it is difficult to adjust the regularity of adjacent convex portions and sufficient antireflection properties cannot be obtained. It was.

  The present invention has been made in view of the above circumstances, and an object thereof is to realize an antireflection article excellent in antireflection properties and design properties.

The antireflective article of the present invention is an antireflective article having a fine concavo-convex structure on its surface, and the distance between adjacent convex parts of the fine concavo-convex structure is equal to or less than the wavelength of visible light, and any convex part The standard deviation of the distance between the centroids of the six convex portions adjacent to the convex portion is 4.0 to 12.0.
Here, it is preferable that the fine uneven structure is formed by a transfer method using anodized alumina as a stamper.

  ADVANTAGE OF THE INVENTION According to this invention, the antireflection article excellent in antireflection property and design property is realizable.

The present invention will be described in detail below.
FIG. 1 is a longitudinal sectional view showing an example of the antireflection article 10 of the present invention. The antireflection article 10 has a cured product 12 of an active energy ray-curable composition on a transparent molded body 11 described later. It is formed. The antireflection article 10 has a fine concavo-convex structure formed on the surface thereof.
The antireflection article 10 may have a fine concavo-convex structure formed on the entire surface, or a fine concavo-convex structure formed on a part of the surface. In particular, when the antireflection article 10 has a film shape, a fine uneven structure may be formed on the entire surface of one surface, or a fine uneven structure may be formed on a part of one surface. Moreover, the fine concavo-convex structure may be formed on the other surface or may not be formed.

In the fine concavo-convex structure, the distance between adjacent convex portions of the fine concavo-convex structure is equal to or less than the wavelength of visible light. Thereby, antireflection property can be expressed. When the distance is larger than the wavelength of visible light, visible light is scattered on the surface on which the fine concavo-convex structure is formed, so that it is not suitable for optical use such as an antireflection article.
In the present invention, “visible light wavelength” means a wavelength of 400 nm. Further, “distance between adjacent convex portions” is a distance w1 from the center of the convex portion 13 of the fine concavo-convex structure to the center of the convex portion adjacent thereto as shown in FIG.

The height of the convex portion 13 is preferably 60 nm or more, and more preferably 90 nm or more. If it is less than 60 nm, the minimum reflectance increases or the reflectance at a specific wavelength increases, resulting in insufficient antireflection properties.
In the present invention, “the height of the convex portion” means a vertical distance d1 from the tip 13a of the convex portion 13 to the bottom portion 14a of the adjacent concave portion 14 as shown in FIG.
Further, the shape of the convex portion 13 having a fine concavo-convex structure is not particularly limited, but in order to obtain an antireflection function that achieves both low reflectance and low wavelength dependency by continuously increasing the refractive index, FIG. A structure that occupies the cross-sectional area continuously when it is cut at the film surface, such as a substantially conical shape or a pyramid shape as shown in FIG. 2, or a bell shape as shown in FIG. 2, is preferable. Further, a plurality of finer convex portions may be combined to form the fine concavo-convex structure.

In the antireflection article of the present invention, the standard deviation of the distance between the centers of gravity of any convex part of the fine concavo-convex structure formed on the surface and the six convex parts adjacent to the convex part is 4.0 to 4.0. 12.0, preferably 4.0 to 9.6. When the standard deviation is less than 4.0, a pattern derived from a stamper, which will be described later, can be seen in the antireflection article, and the design properties are lowered. On the other hand, when the standard deviation is larger than 12.0, a smooth portion is generated between adjacent convex portions, and the antireflection property is deteriorated due to reflection at the smooth portion. In addition, the standard deviation mentioned above is calculated | required with the following method.
First, the surface of the anti-reflective article is observed with an electron microscope (50,000 times), and the obtained image (photograph) is image-analyzed with software such as Image-Pro PLUS (manufactured by Nippon Roper). Calculate the barycentric coordinates of the convex part of the structure. Next, an arbitrary convex portion is selected, six arbitrary points are selected from the convex portions adjacent to the convex portion, and the standard deviation of the coordinate distance from the previous arbitrary convex portion is obtained. The above operation is carried out 10 times, and the average of them is defined as “standard deviation of the distance between the centers of gravity of an arbitrary convex portion of the fine concavo-convex structure and six convex portions adjacent to the convex portion”. The standard deviation is an index of the regularity of the fine uneven structure.

  Further, the reflectance of the antireflection article of the present invention is preferably 1.0% or less, and more preferably 0.8% or less. If the reflectance is greater than 1.0%, it becomes difficult to reduce the reflection sufficiently. The reflectance is a value obtained by measuring the relative reflectance of the surface of the antireflection article on which the fine concavo-convex structure is formed within an incident angle of 5 ° and a wavelength range of 380 nm to 780 nm.

  A method for forming the fine uneven structure on the surface of the antireflection article is not particularly limited, but a transfer method using a stamper is preferable. As a transfer method, for example, a stamper 20 having a fine concavo-convex structure as shown in FIG. 3 is used for injection molding or press molding, and an active material is formed between a stamper having a fine concavo-convex structure and a transparent molded body. A method of filling the energy ray curable composition, curing the active energy ray curable composition by irradiation with active energy rays to transfer the uneven shape of the stamper, and releasing the mold, and a stamper having a fine uneven structure formed thereon The active energy ray-curable composition is filled between the transparent molded products, the stamper uneven shape is transferred to the active energy ray-curable composition, and then released, and then the active energy ray is irradiated to cure the active energy ray. The method of hardening an adhesive composition is mentioned. In particular, considering the transferability of the concavo-convex structure and the degree of freedom of the surface composition, the active energy ray-curable composition is filled between the stamper on which the fine concavo-convex structure is formed and the transparent molded body, and activated by active energy ray irradiation. A method of releasing the mold after curing the energy ray-curable composition to transfer the uneven shape of the stamper is suitable for the present invention.

Although it does not restrict | limit especially as said transparent molded object, When an antireflection article is used for an optical use, what is necessary is just to transmit light. For example, methyl methacrylate (co) polymer, polycarbonate, styrene (co) polymer, methyl methacrylate-styrene copolymer, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, polyester, polyamide, polyimide, polyethersulfone, poly Examples include sulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polyurethane, and glass. The transparent molded body may be produced by any method of injection molding, extrusion molding, and cast molding.
There is no restriction | limiting in particular in the shape of a transparent molded object, Although it can select suitably according to the antireflection article to manufacture, For example, when an antireflection article is an antireflection film etc., a sheet form or a film form is preferable. In addition, the surface of the transparent molded body is subjected to, for example, various coatings and corona discharge treatments in order to improve adhesion to the active energy ray-curable composition, antistatic properties, scratch resistance, weather resistance, and the like. May be.

As shown in FIG. 3, the method of creating the stamper 20 having a fine concavo-convex structure is such that the distance between adjacent convex portions of the fine concavo-convex structure has a wavelength of visible light or less, and an arbitrary convex portion and the convex portion. There is no particular limitation as long as a fine uneven structure in which the standard deviation of the distance between the center of gravity of each of the six convex parts adjacent to the part is 4.0 to 12.0 can be transferred, but it is easy to increase the area and roll. In this respect, it is preferable to use anodized alumina as a stamper.
For example, a recess (pore) 21 having a distance w2 of 20 to 200 nm is formed as shown in FIG. 3 by a method of anodizing aluminum at a predetermined voltage in an electrolyte such as oxalic acid, sulfuric acid, and phosphoric acid. However, this may be used as a stamper. According to this method, after anodizing high-purity aluminum for a long time at a constant voltage, pores can be formed in a self-organized manner by once removing the oxide film and anodizing again. Furthermore, when re-anodizing is performed, a combination of anodizing treatment and pore size enlargement treatment forms a concave-convex structure such as a reverse bell shape in addition to a substantially conical shape or pyramid shape as shown in FIG. Is also possible. Further, as shown in FIG. 3, a replica having a fine concavo-convex structure may be used as a master, and a replication mold may be produced by electroforming or the like, and this may be used as a stamper.
According to the stamper thus created, the distance between adjacent convex portions of the fine concavo-convex structure has a wavelength of visible light or less, and an arbitrary convex portion and six convex portions adjacent to the convex portion. Since the fine concavo-convex structure in which the standard deviation of the distance between the centers of gravity is 4.0 to 12.0 can be transferred, an antireflection article having excellent antireflection properties can be obtained. Moreover, even if high-purity aluminum is used, an antireflection article excellent in design can be obtained.
Further, the shape of the stamper is not particularly limited, and may be a flat plate shape or a roll shape. However, since the fine uneven structure can be continuously transferred to the active energy ray-curable composition by forming the roll shape, the productivity is further increased. Can be preferable.

The active energy ray curable composition used in the present invention causes a curing reaction such as photocuring property, thermosetting property, electron beam curable property, etc., if necessary, and other components that promote or adjust the reaction, etc. And a mixture of a polymerizable compound and a polymerization initiator is included as a main component.
Examples of the polymerizable compound include esterified products obtained from 1 mol of a polyhydric alcohol and 2 mol or more of (meth) acrylic acid or a derivative thereof; a polyhydric alcohol and a polyvalent carboxylic acid or an anhydride thereof; Examples include esterified products obtained from (meth) acrylic acid or its derivatives. Specifically, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Trimethylolethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerin tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, It is obtained from 1 mol of polyhydric alcohol such as tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate and 2 mol or more of (meth) acrylic acid or its derivatives. Esterified products: polyhydric alcohols such as trimethylolethane, trimethylolpropane, glycerin and pentaerythritol, and polyvalent alcohols such as malonic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, fumaric acid, itaconic acid and maleic anhydride Examples thereof include esterified products obtained by a combination arbitrarily selected from carboxylic acid or its anhydride and (meth) acrylic acid or its derivative. These may be used alone or in combination of two or more.

  When utilizing a photocuring reaction, examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl, benzophenone, p-methoxybenzophenone, 2,2-diethoxy. Acetophenone, α, α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4′-bis (dimethylamino) benzophenone, 2-hydroxy-2-methyl-1-phenylpropane- Carbonyl compounds such as 1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoic acid Such as diethoxy phosphine oxide. Moreover, you may use a commercially available photoinitiator. These may be used alone or in combination of two or more.

  When using a thermosetting reaction, examples of the thermal polymerization initiator include methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxy octoate, t Organic peroxides such as butyl peroxybenzoate and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; N, N-dimethylaniline, N, N-dimethyl-p-toluidine And redox polymerization initiators combined with amines such as A commercially available thermal polymerization initiator may be used. These may be used alone or in combination of two or more.

  When utilizing an electron beam curing reaction, examples of the electron beam curing initiator include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, t Thioxanthone such as butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-mol Acetophenone such as linophenyl) -butanone; benzoin ether such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl)- Acylphosphine oxides such as 2,4,4-trimethylpentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; methylbenzoylformate, 1,7-bisacridinylheptane, 9-phenyl Examples include acridine. Moreover, you may use a commercially available electron beam hardening initiator. These may be used alone or in combination of two or more.

The photopolymerization initiator, thermal polymerization initiator, and electron beam curing initiator described above may be used alone or in any desired combination.
Content of these initiators is 0.01-10 mass parts with respect to 100 mass parts of polymeric compounds. When the content is less than 0.01 parts by mass, it becomes difficult to cure sufficiently. On the other hand, when the content is more than 10 parts by mass, the obtained cured product is colored or the mechanical strength is lowered.

Moreover, in addition to what was mentioned above, the non-reactive polymer and the active energy ray sol-gel reactive composition may be mix | blended with the active energy ray curable composition.
Examples of the non-reactive polymer include acrylic resins, styrene resins, polyurethane resins, cellulose resins, polyvinyl butyral resins, polyester resins, and thermoplastic elastomers.

Although it does not specifically limit as an active energy ray sol-gel reactive composition, For example, an alkoxysilane compound, an alkyl silicate compound, etc. are mentioned.
As the alkoxysilane compound, those represented by R _x Si (OR ′) _y can be used, R and R ′ represent an alkyl group having 1 to 10 carbon atoms, and x and y are integers satisfying the relationship of x + y = 4 It is. Specifically, tetramethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, methyltriethoxysilane, methyl Examples include tripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, trimethylpropoxysilane, and trimethylbutoxysilane.
The alkyl silicate ^{compounds, R 1 O [Si (OR} 3) (OR 4) O] those expressed by z ^{R 2} can be ^used, R 1 to R ⁴ each represents an alkyl group having 1 to 5 carbon atoms, z Represents an integer of 3 to 20. Specific examples include methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate, n-butyl silicate, n-pentyl silicate, acetyl silicate and the like.

  Furthermore, various additives such as thickeners, leveling agents, ultraviolet absorbers, light stabilizers, heat stabilizers, solvents, inorganic fillers, and the like are added to the active energy ray-curable composition as necessary. May be.

Specific examples of the active energy ray used when the active energy ray-curable composition is cured include visible rays, ultraviolet rays, electron beams, plasma, infrared rays and the like.
The active energy ray is irradiated with light using, for example, a high-pressure mercury lamp. The light irradiation energy amount is not particularly limited as long as the curing of the resin composition proceeds. For example, 100 to 5000 mJ / cm ² is preferable.

In the antireflection article thus manufactured, the fine uneven structure of the stamper shown in FIG. 3 is transferred on the surface thereof in a relationship between the keyhole and the key. Since the obtained antireflection article is excellent in design and antireflection properties, it is particularly suitable as an antireflection film (including an antireflection film) and a three-dimensional antireflection body.
When the antireflective article has a film shape, for example, an image display device such as a liquid crystal display device, a plasma display panel, an electroluminescence display, a cathode ray tube display device, a lens, a show window, a spectacle lens, a half wavelength Used by sticking to the surface of objects such as plates and low-pass filters.
When the antireflective article has a three-dimensional shape, the antireflective article is manufactured in advance using a transparent molded body having a shape suitable for the application, and this can be used as a member constituting the surface of the object. it can.
Further, when the object is an image display device, the antireflection article may be attached to the front plate, not limited to the surface thereof, or the front plate itself is made of the antireflection article of the present invention. You can also.

  According to the present invention, by using the above-described stamper, for example, optical waveguides, relief holograms, lenses, polarization separation elements, light extraction efficiency improving films, half-wave plates, low-pass filters, crystal devices, etc. Articles, cell culture sheets and the like can also be produced.

  As described above, the antireflection article of the present invention has a fine concavo-convex structure on the surface, and the distance between adjacent convex portions of the fine concavo-convex structure is a wavelength of visible light or less, and thus has excellent antireflection properties. Moreover, since the standard deviation of each center-of-gravity distance between the arbitrary convex part of the fine concavo-convex structure and the six convex parts adjacent to the convex part is 4.0 to 12.0, the design is excellent. . Furthermore, if the height of the convex portion is 60 nm or more, the antireflection property is more excellent. Further, if the reflectance is 1.0 or less, the reflection can be sufficiently reduced.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

<Various evaluations and measurement methods>
(Measurement of reflectance)
The back surface of the manufactured antireflection article (the surface on which the fine uneven structure is not formed) is painted with black spray, and this is used as a sample, using a spectrophotometer (manufactured by Hitachi, “U-4100”) with an incident angle of 5 The relative reflectance of the surface of the antireflection article (the surface on which the fine concavo-convex structure was formed) was measured in the range of 380 nm to 780 nm.

(Design determination)
Each sample was visually checked to see if it had a pattern derived from a grain boundary, and evaluated according to the following criteria.
○: No pattern is visually observed.
X: A pattern can be observed visually.

(Observation of sample surface with electron microscope)
Using a scanning electron microscope (“JSM-7400F” manufactured by JEOL Ltd.), the fine uneven structure formed on the surfaces of the stamper and the antireflection article was observed. In the case of a stamper, the distance between adjacent concave portions and the depth of the concave portion were measured from the obtained image, and in the case of an antireflection article, the distance between adjacent convex portions and the height of the convex portion were measured.
The distance between the concave portions of the fine concavo-convex structure formed on the surface of the stamper is a distance w2 from the center of the concave portion 21 to the center of the concave portion adjacent thereto as shown in FIG. The depth of the concave portion is a vertical distance d2 from the bottom of the concave portion 21 to the tip of the adjacent convex portion.

(Judgment of regularity)
The surface of the antireflective article is observed with a scanning electron microscope (50,000 times), and the obtained image (photograph) is analyzed with image analysis software (“Image-Pro PLUS” manufactured by Nippon Roper Co., Ltd.). The barycentric coordinates of the convex part of were calculated. Next, an arbitrary convex portion was selected, and arbitrary six points were selected from the convex portions adjacent to the convex portion, and the standard deviation of the coordinate distance from the previous arbitrary convex portion was obtained. The above operation was carried out 10 times, and the average value thereof was obtained as the standard deviation, which was used as an index of regularity.

<Active energy ray curable composition>
The raw material of the active energy ray-curable composition and the blending amount thereof are shown below.
Polymerizable compound: trimethylolethaneacrylic acid / succinic anhydride condensed ester (45 parts by mass).
Polymerizable compound: hexanediol diacrylate (45 parts by mass).
Polymerizable compound: “x-22-1602” (manufactured by Shin-Etsu Chemical Co., Ltd., 10 parts by mass).
Photopolymerization initiator: “Irgacure 184” (manufactured by Ciba Specialty Chemicals, 3 parts by mass).
Photopolymerization initiator: “Irgacure 819” (manufactured by Ciba Specialty Chemicals, 0.2 parts by mass).

<Stamper Production Example 1>
An aluminum plate with a purity of 99.99% was anodized in an electrolyte solution of 4.5% oxalic acid aqueous solution for 5 minutes under conditions of a formation voltage of 40 V and 16 ° C., and then alumina with a phosphoric acid / chromic acid mixed solution. The film was selectively dissolved and removed. Further, anodization was performed for 30 seconds in an electrolyte solution of a 2.7% aqueous oxalic acid solution under the same conditions as described above, and a pore size expansion treatment was performed for 8 minutes with a 5% aqueous phosphoric acid solution to obtain porous alumina. Next, porous alumina was dipped for 10 minutes in a solution obtained by diluting fluoroalkylsilane (manufactured by Shin-Etsu Silicone Co., Ltd., “KBM-7803”) with methanol to a solid content of 0.5%, and then air-dried at 120 ° C. A stamper (A) was obtained by heat treatment under reduced pressure for 2 hours.
When the surface of the obtained stamper (A) was observed with an electron microscope, as shown in FIG. 3, from a substantially conical tapered recess (pore) 21 having a distance w2 of 100 nm and a depth d2 of 250 nm. A fine uneven structure was formed.

<Stamper production example 2>
A stamper (B) was produced in the same manner as in Production Example 1 except that the anodic oxidation treatment time in the electrolytic solution of 4.5% oxalic acid aqueous solution was 15 minutes.

<Stamper Production Example 3>
A stamper (C) was produced in the same manner as in Production Example 1 except that the treatment time for anodization in an electrolytic solution of 4.5% oxalic acid aqueous solution was 60 minutes.

<Stamper Production Example 4>
A stamper (D) was produced in the same manner as in Production Example 1 except that the treatment time for anodic oxidation in an electrolytic solution of 4.5% oxalic acid aqueous solution was 1 minute.

<Stamper Production Example 5>
A stamper (E) was produced in the same manner as in Production Example 1, except that the treatment time for anodization in an electrolytic solution of 4.5% oxalic acid aqueous solution was 360 minutes.

[Example 1]
<Manufacture of antireflection articles>
After dropping several drops of the active energy ray-curable composition on the surface of the stamper and spreading with a polyethylene terephthalate film having a thickness of 188 μm (“A-4300” manufactured by Toyobo Co., Ltd.), 1600 mJ / cm ² from the film side. The active energy ray-curable composition was photocured by irradiating ultraviolet rays with energy. Thereafter, the film and the stamper (A) were peeled off to obtain an antireflection article (A).
The surface of the obtained antireflection article (A) has the fine uneven structure of the stamper (A) transferred thereto, and the distance w1 between adjacent protrusions as shown in FIG. 1 is 100 nm, and the height of the protrusions. A fine concavo-convex structure with d1 of 220 nm was formed.

<Evaluation>
Each evaluation of the reflectance, the designability, and the regularity (standard deviation) of the obtained antireflection article (A) was performed. The results are shown in Table 1.

[Example 2]
An antireflection article (B) was produced in the same manner as in Example 1 except that the stamper (B) was used in place of the stamper (A), and the reflectance, design properties, and regularity were evaluated. The results are shown in Table 1.
In addition, the surface of the obtained antireflection article (B) has the fine uneven structure of the stamper (B) transferred thereto, and the distance w1 between adjacent protrusions as shown in FIG. A fine relief structure having a height d1 of 220 nm was formed.

[Example 3]
An antireflection article (C) was produced in the same manner as in Example 1 except that the stamper (C) was used in place of the stamper (A), and the reflectance, design properties, and regularity were evaluated. The results are shown in Table 1.
The surface of the obtained antireflection article (C) has the fine uneven structure of the stamper (C) transferred thereto, and the distance w1 between adjacent protrusions as shown in FIG. A fine relief structure having a height d1 of 220 nm was formed.

[Comparative Example 1]
An antireflection article (D) was produced in the same manner as in Example 1 except that the stamper (D) was used instead of the stamper (A), and each of reflectance, design properties, and regularity was evaluated. The results are shown in Table 1.
In addition, the surface of the obtained antireflection article (D) has the fine uneven structure of the stamper (D) transferred thereto, and the distance w1 between adjacent protrusions as shown in FIG. A fine relief structure having a height d1 of 220 nm was formed.

[Comparative Example 2]
An antireflection article (E) was produced in the same manner as in Example 1 except that the stamper (E) was used in place of the stamper (A), and each of reflectance, design properties, and regularity was evaluated. The results are shown in Table 1.
The surface of the obtained antireflection article (E) has the fine uneven structure of the stamper (E) transferred thereto, and the distance w1 between adjacent protrusions as shown in FIG. A fine relief structure having a height d1 of 220 nm was formed.

As is clear from Table 1, the antireflection articles (A), (B), and (C) of the examples have fine surfaces with standard deviations of 9.6, 8.6, and 4.1, respectively, on the surface. An uneven structure was formed, and both were excellent in regularity and design. Moreover, the reflectance was 1.0% or less, and the antireflection property was also good.
On the other hand, the antireflective article (D) of Comparative Example 1 had a fine uneven structure with a standard deviation of 12.7 formed on the surface thereof, and the design was good, but the regularity was inferior to that of the Examples. The reflectance exceeded 1.0%, and the antireflection property was inferior to the examples.
In addition, since the antireflection article (E) of Comparative Example 2 had a long anodic oxidation treatment time, a fine concavo-convex structure with a standard deviation of 3.1 was formed on the surface, and the regularity was excellent. However, since the anodizing treatment was performed for a long time, the design properties were inferior to those of the examples. The reflectance was 1.0% or less, and the same antireflection property as that of the example was obtained.

It is a longitudinal section showing an example of the antireflection article of the present invention. It is a longitudinal cross-sectional view which shows the other example of the antireflective article of this invention. It is a longitudinal cross-sectional view which shows an example of the stamper used for this invention.

Explanation of symbols

10: Antireflection article 11: Transparent molded body 12: Cured product of active energy ray-curable composition 13: Convex part 14: Concave part 20: Stamper 21: Concave part (pore)

Claims (2)

An antireflective article having a fine relief structure on the surface,
The distance between adjacent convex portions of the fine concavo-convex structure is equal to or less than the wavelength of visible light, and the standard deviation of the distance between the centroids of any convex portion and six convex portions adjacent to the convex portion is An antireflective article characterized by being 4.0 to 12.0.   The antireflection article according to claim 1, wherein the fine uneven structure is formed by a transfer method using anodized alumina as a stamper.

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