JP2014005341A - Article having fine uneven structure on surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article having a fine uneven structure that is excellent in abrasion resistance, on the surface.SOLUTION: One embodiment of this invention is an article having a fine uneven structure made of a cured product of an active energy ray curable resin composition. The active energy ray curable resin composition includes a polymerizable component (X) and a photopolymerization initiator (E), and a vinyl-based polymer (A) having a repeating unit represented by a predetermined formula is included by 15 mass% or more of the polymerizable component (X).

Description

  The present invention relates to an article having on its surface a fine concavo-convex structure made of a cured product of an active energy ray-curable resin composition.

  It is known that an article having a surface with a fine concavo-convex structure having a period equal to or shorter than the wavelength of visible light has antireflection performance due to a continuous change in refractive index in the fine concavo-convex structure. It is also known that the fine concavo-convex structure has super water-repellent performance due to the lotus effect.

As a method for manufacturing an article having a fine concavo-convex structure on the surface, for example, the following method has been proposed.
(I) A method of transferring a fine concavo-convex structure to a thermoplastic resin when a thermoplastic resin is injection-molded or press-molded using a stamper having an inverted structure of the fine concavo-convex structure on the surface.
(Ii) An active energy ray-curable resin composition is filled between a stamper having a reverse structure of a fine concavo-convex structure on the surface and a transparent substrate, cured by irradiation with active energy rays, and then the stamper is released And transferring the fine relief structure to the cured product. Alternatively, after filling the active energy ray-curable resin composition between the stamper and the transparent substrate, the stamper is released to transfer the fine concavo-convex structure to the active energy ray-curable resin composition. A method of curing an active energy ray-curable resin composition by irradiation with energy rays.

Among these, the transferability of the fine concavo-convex structure is good, the composition surface has a high degree of freedom, and continuous production is possible when the stamper is a belt or a roll. ) Is attracting attention.
As the active energy ray-curable resin composition used in the method (ii), for example, the following compositions have been proposed.
(1) A photocurable resin composition containing an acrylate oligomer such as urethane acrylate, an acrylic resin having a radical polymerizable functional group, a release agent, and a photopolymerization initiator (Patent Document 1).
(2) An ultraviolet curable resin composition containing a polyfunctional (meth) acrylate such as trimethylolpropane tri (meth) acrylate, a photopolymerization initiator, and a leveling agent such as polyether-modified silicone oil (Patent Document 2) .

Japanese Patent No. 4156415 JP 2000-71290 A

  However, the photocurable resin composition (1) may be easily damaged by rubbing the surface of the cured product.

  Moreover, since the ultraviolet curable resin composition of said (2) uses the low molecular weight polymeric component, a hardened | cured material becomes weak and may be easily damaged by rubbing.

  The objective of this invention is providing the articles | goods which have the fine concavo-convex structure which is excellent in abrasion resistance on the surface.

One aspect of the present invention is:
An article having on the surface a fine concavo-convex structure made of a cured product of an active energy ray-curable resin composition,
The active energy ray-curable resin composition contains a polymerizable component (X) and a photopolymerization initiator (E),
The polymerizable component (X) is an article containing 15% by mass or more of the vinyl polymer (A) having a repeating unit represented by the following formula (1) in the polymerizable component (X).

[In formula (1), R ¹ is an alkylene group having 2 to 8 carbon atoms, R ² is a hydrogen atom or a methyl group, and m is a positive integer].

  In another preferred embodiment of the present invention, the fine concavo-convex structure is the article in which an average interval between the convex portions is not more than a visible light wavelength.

  In another preferred embodiment of the present invention, the fine concavo-convex structure is the article in which a ratio of the convex part height (aspect ratio) to an average interval between the convex parts is 0.5 to 5.

  In another preferred embodiment of the present invention, the fine concavo-convex structure is the article having a structure in which the concavo-convex is regularly arranged.

  Another preferred form of the present invention is the article which is an antireflective article.

One aspect of the present invention is:
A method for producing an article having a fine relief structure on its surface,
Active energy ray curing containing a polymerizable component (X) containing 15% by mass or more of a vinyl polymer (A) having a repeating unit represented by the above formula (1), and a photopolymerization initiator (E). It is the manufacturing method of the articles | goods which form the said fine concavo-convex structure using a conductive resin composition.

  In another preferred embodiment of the present invention, after the active energy ray-curable resin composition is disposed between a base material and a stamper having an inverted structure of the fine concavo-convex structure, the active energy ray is irradiated to irradiate the active energy. It is a manufacturing method of the said article which forms the above-mentioned fine concavo-convex structure by hardening a line hardening resin composition.

  Another preferred embodiment of the present invention is a method for manufacturing an antireflection article by the method for manufacturing an article.

  According to the present invention, an article having a fine concavo-convex structure with excellent scratch resistance on the surface can be obtained.

It is sectional drawing which shows an example of the article | item which has the fine concavo-convex structure of this invention on the surface. It is sectional drawing which shows the manufacturing process of the stamper which has an anodized alumina on the surface. It is a block diagram which shows an example of the manufacturing apparatus of the articles | goods which have the fine concavo-convex structure of this invention on the surface.

  In the present specification, the radical polymerizable functional group means a (meth) acryloyl group, a vinyl group or the like. The (meth) acryloyl group means an acryloyl group and / or a methacryloyl group. (Meth) acrylate means acrylate and / or methacrylate. Moreover, an active energy ray means visible light, an ultraviolet-ray, an electron beam, plasma, a heat ray (infrared rays etc.), etc.

<Active energy ray-curable resin composition>
The active energy ray-curable resin composition is a resin composition that cures by irradiating active energy rays so that a polymerization reaction proceeds.

  The active energy ray-curable resin composition of the present invention contains a polymerizable component (X) and a photopolymerization initiator (E). Moreover, an active energy ray curable resin composition contains other components, such as a ultraviolet absorber or antioxidant, as needed.

(Polymerizable component (X))
The polymerizable component (X) includes a vinyl polymer (A) having a repeating unit represented by the following formula (1).

[In formula (1), R ¹ is an alkylene group having 2 to 8 carbon atoms, R ² is a hydrogen atom or a methyl group, and m is a positive integer].

  The polymerizable component (X) may contain the monomer (B) as a polymerization component other than the vinyl polymer (A).

  In Formula (1), m is an integer of 1-8, for example, it is preferable that it is an integer of 1-6, and it is more preferable that it is an integer of 1-4.

(Vinyl polymer (A))
The vinyl polymer (A) is a (meth) acryloyl group pendant type polymer obtained by selectively cationically polymerizing only vinyl ether in a heterogeneous polymerizable monomer having vinyl ether and (meth) acryloyl group in the molecule. It is a coalescence or copolymer.

  The vinyl polymer (A) can prevent the fine concavo-convex structure from being broken and broken by the entanglement effect of the main chain of the (meth) acryloyl group pendant type polymer or copolymer. Further, the relatively high cross-linking density obtained by curing with active energy rays can prevent the projections of fine irregularities from being united.

  On the other hand, when a monomer or oligomer having a rigid molecular structure such as an aromatic ring or alicyclic structure, which is generally considered effective in conventional hard coats, is used, the resulting fine concavo-convex structure is weak against abrasion. May break easily. In addition, when a curable resin composition containing a large proportion of a polyfunctional monomer having a small molecular weight and a small acrylic equivalent is used, the resulting fine concavo-convex structure has a high crosslinking density but a large strain and a brittle cured product. As a result, the resulting fine uneven structure may be easily broken.

  In order for the vinyl polymer (A) to give excellent scratch resistance to the fine relief structure, the acrylic equivalent of the vinyl polymer (A) is preferably 140 or more and less than 220, and 160 or more and less than 200. More preferably. In addition, in order for the vinyl polymer (A) to give excellent scratch resistance to the fine uneven structure, the number average molecular weight of the vinyl polymer (A) is preferably 2000 or more, more preferably 10,000 or more, and 20000. The above is more preferable.

  Examples of the vinyl polymer (A) include vinyl polymers described in JP 2008-303310 A, JP 2008-214453 A, and the like. Specific examples include compounds obtained by selectively polymerizing only the vinyl ether group of 2- (2-vinyloxyethoxy) ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd .: VEEA). Two or more types of vinyl polymers (A) may be used in combination.

  By setting the content of the vinyl polymer (A) to 15% by mass or more in the polymerizable component (X), excellent scratch resistance can be imparted to the fine uneven structure. The content of the vinyl polymer (A) is preferably 35% by mass or more, and more preferably 50% by mass or more.

(Monomer (B))
A monomer (B) can be added in order to provide various functionalities to the fine concavo-convex structure or to balance the performance. As the monomer (B), two or more kinds can be used in combination. Hereinafter, the optimum monomer (B) according to the purpose will be described. The content of the monomer (B) is preferably 85% by mass or less and more preferably 65% by mass or less in the polymerizable component (X) in order not to impair the good scratch resistance of the vinyl polymer (A). Preferably, 50 mass% or less is more preferable.

(Prevention of protrusion unity)
In order to prevent uniting of protrusions without impairing the scratch resistance of the fine concavo-convex structure, it is important to control the crosslinking density of the cured product. In order to increase the crosslinking density, it is preferable to use a monomer having a (meth) acryloyl group of 3 or more and an acrylic equivalent of less than 150 as the monomer (B).

  Specific examples of the monomer (B) include polypentaerythritol poly (meth) acrylate, tripentaerythritol poly (meth) acrylate, dipentaerythritol (penta) hexa (meth) acrylate, and pentaerythritol (tri) tetra. (Meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, and alkylene oxide adducts and caprolactone modified products of the above monomers, trifunctional or more polyfunctional Examples include urethane (meth) acrylate, trifunctional or higher polyfunctional epoxy (meth) acrylate, trifunctional or higher polyfunctional polyester (meth) acrylate, and the like.

(Give hydrophilicity)
When hydrophilicity is imparted to the surface of the fine concavo-convex structure, dirt such as fingerprints can be removed by wiping with water. Further, it is possible to impart antifogging properties. Examples of the monomer (B) that can be preferably used to make the surface of the fine unevenness hydrophilic include a monomer having a polyethylene glycol chain or a polyethylene oxide chain, a monomer having an acrylamide group or a hydroxyl group, and the like. Specific examples of the monomer (B) include triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxytetra Ethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, N, N-dimethylacrylamide, hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Acrylate, 4-hydroxybutyl (meth) acrylate, epoxy (meth) acrylates and the like.

(Grant water repellency)
When water repellency is imparted to the surface of the fine concavo-convex structure, a higher contact angle can be realized with respect to various liquids as compared with the case of a flat surface. This is also called the lotus effect, and is an antifouling function due to super water-repellent properties found in plants such as lotus leaves and insects such as cicada wings in nature.

  Examples of the monomer (B) that can be preferably used for imparting water repellency to the surface of the fine concavo-convex structure include a monomer having a long chain alkyl group, a monomer having a silicone skeleton, and a monomer having a fluorine-containing group. Specific examples of the monomer (B) include tert-butyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, branched alkyl ( (Meth) acrylate, X-22-1602 (manufactured by Shin-Etsu Chemical Co., Ltd.), TEGO Rad2100, TEGO Rad2200N, TEGO Rad2250, TEGO Rad2300, TEGO Rad2500, TEGO Rad2600, TEGO Rad2650, TEGO Rad2700 (above, manufactured by Evonik Degussa, trade name) ), BYK-3500, BYK-UV3570 (above, manufactured by BYK Chemie, trade name), OPTOOL DAC (made by Daikin Industries, trade name), PolyFox P -3320 (manufactured by OMNOVA, trade name), Fluorolink MD500, Fluorolink MD700, Fluorolink 5110X, Fluorolink 5105X, Fluorolink 5101X, Y, Fluorolink AD1700 (C, Y, CR, 8) C6DIMTCRY (above, product name manufactured by EXfluor), V # 3F, V # 3FM, V # 4F, V # 8F, V # 8FM (above, product name made by Osaka Organic Chemical Industry Co., Ltd.), and the like.

(Viscosity adjustment)
In order to adjust the polymerizable component (X) to a viscosity suitable for forming a fine uneven structure on the surface, the monomer (B) can be appropriately selected. Although the preferable range of the viscosity of the polymerizable component (X) varies depending on the production method, for example, the resin viscosity at 25 ° C. is preferably 10 to 40,000 mPa · sec, and more preferably 20 to 20000 mPa · sec. 50 to 5000 mPa · sec is more preferable. When the viscosity of the vinyl polymer (A) is low, a monomer (B) having a higher viscosity is selected. When the viscosity of the vinyl polymer (A) is high, a monomer having a lower viscosity ( It is preferred to select B).

  Examples of the relatively high viscosity monomer (B) include methyl (meth) acrylate macromers and various urethane acrylates. Examples of the monomer (B) having a relatively low viscosity include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonanediol. Di (meth) acrylate, 1,10-decanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polybutylene glycol di (meth) ) Acrylate, hydroxybivalic acid neopentyl glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, N, N-diethyl (meth) acrylamide, tert-butyl (meth) acrylamide, diacetone ( Examples include meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, and 2-hydroxy-3-acryloyloxypropyl methacrylate. .

(Refractive index adjustment)
When the cured product of the active energy ray-curable resin composition having a fine concavo-convex structure is formed on a transparent substrate, it is preferable to make the refractive index of the transparent substrate and the fine concavo-convex structure as close as possible. Thereby, the antireflection performance is appropriately expressed by the fine concavo-convex structure.

  In order to reduce the refractive index of the cured product of the active energy ray-curable resin composition, for example, it is preferable to contain a fluorine-containing monomer. The monomer (B) that can be used for imparting water repellency can be used as the monomer (B) capable of lowering the refractive index.

  From the viewpoint of making the cured product of the active energy ray-curable resin composition have a high refractive index, it is effective to introduce an aromatic ring or an alicyclic structure. However, when a large number of aromatic or alicyclic structures are introduced, the scratch resistance of the fine concavo-convex structure tends to be impaired. Therefore, the monomer having an aromatic ring or alicyclic structure is preferably less than 25% by mass and more preferably less than 15% by mass in the polymerizable component (X).

  Moreover, in order to make the hardened | cured material of an active energy ray curable resin composition high refractive index, a bromine containing monomer, a sulfur containing monomer, etc. are suitable. Further, inorganic fine particles having a high refractive index such as nano zirconia may be added.

(Photopolymerization initiator (E))
The photopolymerization initiator (E) is a compound that generates a radical that is cleaved by irradiating active energy rays to initiate a polymerization reaction. As the active energy ray, ultraviolet rays are preferable from the viewpoint of apparatus cost and productivity. Radicals are generated by irradiating the photopolymerization initiator (E) with active energy rays, and the vinyl group of the vinyl polymer (A) undergoes a polymerization reaction.

  As the photopolymerization initiator (E) that generates radicals by ultraviolet rays, that is, the photopolymerization initiator, for example, benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, thioxanthones (2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, etc.), acetophenones (diethoxyacetophenone, 2-hydroxy-2-phenyl) Methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, etc.), benzoin ethers (benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc.), acylphosphine oxides (2 , 4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc.) Examples include methylbenzoyl formate, 1,7-bisacridinyl heptane, 9-phenylacridine and the like.

  A photoinitiator may be used individually by 1 type and may use 2 or more types together. When using together, it is preferable to use together 2 or more types from which absorption wavelength differs.

  Moreover, you may use together thermal polymerization initiators, such as persulfate (potassium persulfate, ammonium persulfate, etc.), peroxides (benzoyl peroxide, etc.), an azo initiator, as needed.

  The content of the photopolymerization initiator (E) in the active energy ray-curable resin composition is preferably 0.01 to 10 parts by mass, and 0.1 to 5 parts by mass with respect to 100 parts by mass of the polymerizable component (X). Part is more preferable, and 0.2 to 3 parts by mass is further preferable. If the content of the photopolymerization initiator (E) is 0.01 parts by mass or more, the active energy ray-curable resin composition can be sufficiently cured, and the mechanical properties of an article having a fine uneven structure on the surface can be obtained. Can be good. If content of a photoinitiator (E) is 10 mass parts or less, it can prevent that an unreacted photoinitiator (E) remains in hardened | cured material. If the photopolymerization initiator remains unreacted in the cured product, the unreacted photopolymerization initiator may act as a plasticizer, which may impair scratch resistance. Moreover, an unreacted photopolymerization initiator may cause coloring.

(Ultraviolet absorber, antioxidant)
The active energy ray-curable resin composition may further contain an ultraviolet absorber and / or an antioxidant.

  Examples of the ultraviolet absorber include benzophenone, benzotriazole, hindered amine, benzoate, and triazine. Examples of commercially available products include UV absorbers such as “Tinuvin 400” and “Tinuvin 479” manufactured by Ciba Specialty Chemicals, and “Viosorb110” manufactured by Kyodo Pharmaceutical.

  Examples of the antioxidant include hindered phenol-based, benzimidazole-based, phosphorus-based, sulfur-based and hindered amine-based antioxidants. Examples of commercially available products include “IRGANOX” series manufactured by Ciba Specialty Chemicals.

  These ultraviolet absorbers and antioxidants may be used alone or in combination of two or more.

  It is preferable that content of a ultraviolet absorber and antioxidant is 0.01-5 mass% in total with respect to 100 mass parts of polymeric components (X).

(Other ingredients)
The active energy ray-curable resin composition may be a surfactant, a release agent, a lubricant, a plasticizer, an antistatic agent, a light stabilizer, a flame retardant, a flame retardant aid, a polymerization inhibitor, or a filler, if necessary. In addition, known additives such as a silane coupling agent, a colorant, a reinforcing agent, an inorganic filler, and an impact modifier may be included.

  Moreover, the active energy ray-curable resin composition may contain an oligomer or polymer that does not have a radical polymerizable functional group, a trace amount of an organic solvent, and the like, if necessary.

  Since the active energy ray-curable resin composition described above contains the polymerizable component (X) at a specific ratio, a cured product having fine unevenness with good scratch resistance can be formed.

<Articles having a fine relief structure on the surface>
Articles having a fine concavo-convex structure on the surface are articles having a fine concavo-convex structure formed on the surface by contacting and curing the active energy ray-curable resin composition with a stamper having an inverted structure of the fine concavo-convex structure on the surface. It is.

  FIG. 1 is a cross-sectional view showing an example of an article having a fine relief structure on the surface. The article 40 includes a base material 42 and a cured resin layer 44 formed on the surface of the base material 42.

  The substrate 42 is preferably a molded body that transmits light. Examples of the base material include acrylic resin (polymethyl methacrylate, etc.), polycarbonate, styrene (co) polymer, methyl methacrylate-styrene copolymer, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, polyester ( Polyethylene terephthalate, etc.), polyamide, polyimide, polyether sulfone, polysulfone, polyolefin (polyethylene, polypropylene, etc.), polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polyurethane, glass and the like.

  The base material 42 is, for example, an injection molded body, an extrusion molded body, or a cast molded body. Moreover, the shape of the base material 42 is a sheet form and a film form, for example.

  The surface of the base material 42 may be subjected to a coating treatment, a corona treatment or the like in order to improve adhesion, antistatic properties, scratch resistance, weather resistance and the like.

  The cured resin layer 44 is a film made of a cured product of the active energy ray curable resin composition, and has a fine uneven structure on the surface.

  When an anodic alumina stamper described later is used, the fine uneven structure on the surface of the article 40 is formed by transferring the fine uneven structure on the surface of the anodized alumina, and the active energy ray-curable resin composition And a plurality of convex portions 46 made of a cured product.

  As the fine concavo-convex structure, a so-called moth-eye structure in which a plurality of protrusions (convex portions) having a substantially conical shape or a pyramid shape are arranged is preferable. It is known that the moth-eye structure in which the distance between the protrusions is less than or equal to the wavelength of visible light exhibits an effective antireflection function by continuously increasing the refractive index from the refractive index of air to the refractive index of the material. ing.

  The average interval between the convex portions is preferably not more than the wavelength of visible light, that is, not more than 400 nm. If the average interval between the convex portions is 400 nm or less, the scattering of visible light can be suppressed, and an excellent antireflection function can be achieved. For example, when convex portions are formed using an anodic alumina stamper described later, the average interval between the convex portions is about 100 nm. Further, the average interval between the convex portions is more preferably 200 nm or less, and further preferably 150 nm or less.

  The average interval between the convex portions is preferably 20 nm or more from the viewpoint of easy formation of the convex portions.

  The average interval between the convex portions is obtained by measuring 50 intervals between adjacent convex portions (distance from the center of the convex portion to the center of the adjacent convex portion) by electron microscope observation, and averaging these values. .

When the average interval between the convex portions is about 100 nm, the height of the convex portions is preferably 50 to 500 nm, more preferably 120 to 400 nm, and further preferably 150 to 300 nm. If the height of the convex portion is 50 nm or more, the reflectance is sufficiently low, and the wavelength dependency of the reflectance is reduced. If the height of a convex part is 500 nm or less, the scratch resistance of a convex part will become favorable.
The height of the convex portion is a value obtained by measuring the distance between the topmost portion of the convex portion and the bottommost portion of the concave portion existing between the convex portions when observed with an electron microscope at a magnification of 30000 times.

  0.5-5 are preferable, as for the aspect ratio (height of a convex part / average space | interval between convex parts) of a convex part, 1.2-4 are more preferable, and 1.5-3 are especially preferable. If the aspect ratio of the convex portion is 0.5 or more, the reflectance is sufficiently low. When the aspect ratio of the convex portion is 5 or less, the scratch resistance of the convex portion is good.

  The fine uneven structure has a structure in which unevenness is regularly arranged. The higher the regularity of the fine uneven structure, the better. The more uniform the interval between the convex portions of the fine concavo-convex structure, the higher the regularity, and ideally a hexagonal close packed structure. And the higher the regularity, the smaller the flat surface of the bottom of the recess can be made. As a result, the reflectance can be kept low.

  The shape of the convex part is a shape in which the convex sectional area in the direction perpendicular to the height direction continuously increases in the depth direction from the outermost surface, that is, the sectional shape in the height direction of the convex part is a triangle, trapezoid, A shape such as a bell shape is preferred.

  The difference between the refractive index of the cured resin layer 44 and the refractive index of the substrate 42 is preferably 0.2 or less, more preferably 0.1 or less, and even more preferably 0.05 or less. When the refractive index difference is 0.2 or less, reflection at the interface between the cured resin layer 44 and the base material 42 is suppressed.

(Stamper)
The stamper has an inverted structure of a fine concavo-convex structure on the surface.

  Examples of the material of the stamper include metals (including those having an oxide film formed on the surface), quartz, glass, resin, ceramics, and the like.

  Examples of the shape of the stamper include a roll shape, a circular tube shape, a flat plate shape, and a sheet shape.

Examples of the stamper manufacturing method include the following method (I-1) and method (I-2). In addition, the method (I-1) is preferable from the viewpoint that the area can be increased and the production is simple.
(I-1) A method of forming anodized alumina having a plurality of pores (concave portions) on the surface of an aluminum substrate.
(I-2) A method of forming an inverted structure of a fine concavo-convex structure on the surface of a stamper base material by an electron beam lithography method, a laser beam interference method, or the like.

As the method (I-1), a method having the following steps (a) to (f) is preferable.
(A) A step of forming an oxide film on the surface of an aluminum substrate by anodizing the aluminum substrate in an electrolytic solution under a constant voltage.
(B) A step of removing the oxide film and forming anodic oxidation pore generation points on the surface of the aluminum substrate.
(C) After the step (b), the step of anodizing the aluminum substrate again in the electrolytic solution to form an oxide film having pores at the pore generation points.
(D) A step of expanding the diameter of the pores after the step (c).
(E) A step of anodizing again in the electrolytic solution after the step (d).
(F) A step of repeatedly performing step (d) and step (e) to obtain a stamper in which anodized alumina having a plurality of pores is formed on the surface of an aluminum substrate.

Step (a):
As shown in FIG. 2, when the aluminum substrate 10 is anodized, an oxide film 14 having pores 12 is formed.

  Examples of the shape of the aluminum substrate include a roll shape, a circular tube shape, a flat plate shape, and a sheet shape.

  Since the oil used when processing the aluminum base material into a predetermined shape may be adhered, it is preferable to degrease the aluminum base material in advance. The aluminum substrate is preferably subjected to electrolytic polishing (etching) in order to smooth the surface state.

  The purity of aluminum is preferably 99% or more, more preferably 99.5% or more, and further preferably 99.8% or more. When the purity of aluminum is low, when anodized, an uneven structure having a size to scatter visible light may be formed due to segregation of impurities, or the regularity of pores obtained by anodization may be lowered.

  Examples of the electrolytic solution include sulfuric acid, oxalic acid, phosphoric acid, and the like.

-When using oxalic acid as electrolyte solution The concentration of oxalic acid is preferably 0.7 M or less. When the concentration of oxalic acid exceeds 0.7M, the current value becomes too high, and the surface of the oxide film may become rough.

When the formation voltage is 30 to 60 V, anodized alumina having highly regular pores with a period of 100 nm can be obtained. Regardless of whether the formation voltage is higher or lower than this range, the regularity tends to decrease.
The temperature of the electrolytic solution is preferably 60 ° C. or lower, and more preferably 45 ° C. or lower. When the temperature of the electrolytic solution exceeds 60 ° C., a so-called “burn” phenomenon occurs, and the pores may be broken, or the surface may melt and the regularity of the pores may be disturbed.

-When using sulfuric acid as electrolyte solution The concentration of sulfuric acid is preferably 0.7 M or less. If the concentration of sulfuric acid exceeds 0.7M, the current value may become too high to maintain a constant voltage.
When the formation voltage is 25 to 30 V, anodized alumina having highly regular pores with a period of 63 nm can be obtained. The regularity tends to decrease whether the formation voltage is higher or lower than this range.
The temperature of the electrolytic solution is preferably 30 ° C. or lower, and more preferably 20 ° C. or lower. When the temperature of the electrolytic solution exceeds 30 ° C., a so-called “burn” phenomenon occurs, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

Step (b):
As shown in FIG. 2, the regularity of the pores can be improved by removing the oxide film 14 once and using it as the pore generation points 16 for anodic oxidation.

  Examples of the method for removing the oxide film include a method in which aluminum is not dissolved but is dissolved in a solution that selectively dissolves the oxide film and removed. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

Step (c):
As shown in FIG. 2, when the aluminum substrate 10 from which the oxide film has been removed is anodized again, an oxide film 14 having cylindrical pores 12 is formed.

  Anodization may be performed under the same conditions as in step (a). Deeper pores can be obtained as the anodic oxidation time is lengthened.

Step (d):
As shown in FIG. 2, a process for expanding the diameter of the pores 12 (hereinafter referred to as a pore diameter expansion process) is performed. The pore diameter expansion treatment is a treatment for expanding the diameter of the pores obtained by anodic oxidation by immersing in a solution dissolving the oxide film. Examples of such a solution include a phosphoric acid aqueous solution of about 5% by mass.

  The longer the pore diameter expansion processing time, the larger the pore diameter.

Step (e):
As shown in FIG. 2, when anodized again, cylindrical pores 12 having a small diameter that extend downward from the bottom of the cylindrical pores 12 are further formed.

  Anodization may be performed under the same conditions as in step (a). Deeper pores can be obtained as the anodic oxidation time is lengthened.

Step (f):
As shown in FIG. 2, when the pore diameter enlargement process in the step (d) and the anodization in the step (e) are repeated, the pores 12 have a shape in which the diameter continuously decreases in the depth direction from the opening. An oxide film 14 is formed, and a stamper 18 having anodized alumina (aluminum porous oxide film (alumite)) on the surface of the aluminum substrate 10 is obtained. It is preferable that the last end is step (d).

  The number of repetitions is preferably 3 times or more, and more preferably 5 times or more. When the number of repetitions is 3 times or more, the diameter of the pores continuously decreases, so the effect of reducing the reflectance of the moth-eye structure formed using such anodized alumina having such pores is sufficient. .

  Examples of the shape of the pore 12 include a substantially conical shape, a pyramid shape, a cylindrical shape, and the like, and a cross-sectional area of the pore in a direction orthogonal to the depth direction such as a conical shape and a pyramid shape is from the outermost surface. A shape that continuously decreases in the depth direction is preferable.

The average interval between the pores 12 is not more than the wavelength of visible light, that is, not more than 400 nm. The average interval between the pores 12 is preferably 20 nm or more.
The average interval between the pores 12 was measured by measuring the distance between adjacent pores 12 (distance from the center of the pore 12 to the center of the adjacent pore 12) by electron microscope observation, and averaging these values. It is a thing.

  When the average interval is 100 nm, the depth of the pores 12 is preferably 80 to 500 nm, more preferably 120 to 400 nm, and further preferably 150 to 300 nm.

The depth of the pore 12 is a value obtained by measuring the distance between the bottom of the pore 12 and the top of the convex portion existing between the pores 12 when observed with an electron microscope at a magnification of 30000 times. It is.
The aspect ratio of the pores 12 (depth of pores / average interval between pores) is preferably 0.8 to 5.0, more preferably 1.2 to 4.0, and 1.5 to 3.0. Is more preferable.

  The surface of the stamper on which the fine uneven structure is formed may be treated with a release agent.

  Examples of the release agent include silicone resins, fluororesins, and fluorine compounds, and fluorine compounds having a hydrolyzable silyl group are preferable. Commercially available fluorine compounds having hydrolyzable silyl groups include fluoroalkylsilanes, KBM-7803 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name), MRAF (Asahi Glass, trade name), OPTOOL HD1100, HD2100 series (manufactured by Harves) , Trade name), OPTOOL AES4, AES6 (trade name, manufactured by Daikin Industries, Ltd.), Novec EGC-1720 (trade name, manufactured by Sumitomo 3M), FS-2050 series (trade name, manufactured by Fluoro Technology), and the like. .

(Product manufacturing method)
An article having a fine concavo-convex structure on its surface is manufactured as follows using, for example, a manufacturing apparatus shown in FIG.

  Active energy ray curable from the tank 22 between a roll-shaped stamper 20 having an inverted structure (not shown) having a fine concavo-convex structure on the surface and a strip-shaped film base material 42 moving along the surface of the roll-shaped stamper 20. A resin composition is supplied.

  The base material 42 and the active energy ray-curable resin composition are sandwiched between the roll-shaped stamper 20 and the nip roll 26 whose nip pressure is adjusted by the pneumatic cylinder 24. Then, the active energy ray-curable resin composition is uniformly distributed between the base material 42 and the roll-shaped stamper 20, and at the same time, filled into the concave portions of the fine uneven structure of the roll-shaped stamper 20.

  The active energy ray curable resin composition is irradiated from the active energy ray irradiating device 28 installed below the roll-shaped stamper 20 through the base material 42 to the active energy ray curable resin composition, and the active energy ray curable resin composition is cured. A cured resin layer 44 to which the fine uneven structure on the surface of the roll stamper 20 is transferred is formed.

  An article 40 as shown in FIG. 1 is obtained by peeling the substrate 42 having the cured resin layer 44 formed on the surface from the roll stamper 20 by the peeling roll 30.

As the active energy ray irradiation device 28, a high-pressure mercury lamp, a metal halide lamp, or the like is preferable. In this case, the amount of light irradiation energy is preferably 100 to 10,000 mJ / cm ² .

  The substrate 42 is preferably a light transmissive film. Examples of the film material include acrylic resin, polycarbonate, styrene resin, polyester, cellulose resin (such as triacetyl cellulose), polyolefin, and alicyclic polyolefin.

(Use)
The article having the fine concavo-convex structure of the present invention on the surface is an antireflection film, an antireflection article such as an antireflection film, a touch panel, an optical waveguide, a relief hologram, a lens, an optical article such as a polarization separation element, or a cell culture sheet. Is particularly suitable for use as an antireflection article.

  Examples of antireflection articles include antireflection films and antireflection films provided on the surfaces of image display devices (liquid crystal display devices, plasma display panels, electroluminescence displays, cathode tube display devices, etc.), lenses, show windows, and glasses. And an antireflection sheet. When used in an image display device, an antireflection film may be directly attached to the image display surface, an antireflection film may be directly formed on the surface of a member constituting the image display surface, or an antireflection film is formed on the front plate. May be formed.

  The article having the fine concavo-convex structure of the present invention described above on the surface is excellent in scratch resistance of the fine concavo-convex structure because the active energy ray-curable resin composition described above is used.

(Example)
Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

(Abrasion resistance)
Using a wear tester (manufactured by Shinto Kagaku Co., “HEiDON”), a load of 100 g was applied to 2 cm square steel wool (Nihon Steel Wool Co., Ltd., Bonster # 0000) placed on the surface of the article, and the reciprocating distance: After reciprocating 10 times at 30 mm and a head speed of 30 mm / second, the appearance of the surface of the article was evaluated. In the appearance evaluation, an article was attached to one side of a black 2.0 mm thick acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd.) and evaluated visually.

A: Even if the fluorescent light is reflected indoors, scratches are not recognized.
○: Slightly visible when a fluorescent lamp is reflected indoors.
X: Scratches appear white without reflecting the fluorescent lamp.

(Fingerprint wiping property)
After wiping the surface of the article with fingerprints on the surface in one direction using a wiper (Dao Paper Co., Ltd., Erière Pro Wipe) in which 1.0 cc of tap water was dyed in a range of about 5 cm in diameter, The appearance of the surface was evaluated.

○: Fingerprints can be completely removed by wiping twice or less.
Δ: Fingerprints can be completely removed by wiping 3 to 10 times.
X: Fingerprints remain even after wiping 10 times.

(Water repellency)
A contact angle meter DM-301 manufactured by Kyowa Interface Science Co., Ltd. was used to measure the contact angle of pure water with respect to the article. Pure water was deposited on the surface of a 3.0 μL article, the contact angle 5 seconds after the deposition was measured three times, and the average value was calculated.

◎: Contact angle of pure water is 130 ° or more ○: Contact angle of pure water is 100 ° or more and less than 130 ° ×: Contact angle of pure water is less than 100 °

(Manufacture of stampers)
An aluminum plate having a purity of 99.99% was mirror-polished by polishing a feather and electropolishing in a perchloric acid / ethanol mixed solution (1/4 volume ratio).

Step (a):
The aluminum plate was anodized in a 0.3 M oxalic acid aqueous solution for 30 minutes under conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (b):
The aluminum plate on which the oxide film was formed was immersed in a 6% by mass phosphoric acid / 1.8% by mass chromic acid mixed aqueous solution for 6 hours to remove the oxide film.

Step (c):
The aluminum plate was anodized in a 0.3 M oxalic acid aqueous solution for 30 seconds under conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (d):
The aluminum plate on which the oxide film was formed was immersed in 5% by mass phosphoric acid at 32 ° C. for 8 minutes to carry out pore diameter expansion treatment.

Step (e):
The aluminum plate was anodized in a 0.3 M oxalic acid aqueous solution for 30 seconds under conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (f):
Step (d) and step (e) were repeated four times, and finally step (d) was carried out, and anodized alumina having substantially conical pores with an average interval of 100 nm and a depth of 180 nm was formed on the surface. I got a stamper.

  After the obtained stamper was washed with deionized water, water on the surface was removed by air blow, and OPTOOL DSX (manufactured by Daikin Industries, Ltd.) was diluted with a diluent HD-ZV (Harves) so that the solid content was 0.1% by mass. The product was dipped in a solution diluted with (made by Kogyo Co., Ltd.) for 10 minutes, pulled up from the solution and air-dried for 20 hours to obtain a stamper treated with a release agent.

(Production Example 1)
80 g of toluene was added to a four-necked flask equipped with a stirrer, a thermometer, a dropping line, and a nitrogen / air mixed gas introduction tube, and cooled to 15 ° C. After cooling, 200 g of VEEA (manufactured by Nippon Shokubai Co., Ltd.) and a mixed solution of 27 g of ethyl acetate and 13.5 mg of phosphotungstic acid were added dropwise over 2 hours. After completion of the dropping, polymerization was continued at 15 ° C. After completion of the polymerization, the reaction was terminated by adding triethylamine. Subsequently, after concentrating with an evaporator, a vinyl polymer (PVEEA-1) was obtained. The reaction rate of the monomer was found to be 99.6% by analyzing the mixed solution after stopping the reaction by gas chromatography (GC). Moreover, the number average molecular weight (Mn) of the obtained vinyl polymer was 10,200, and molecular weight distribution (Mw / Mn) was 2.27.

(Polymerization component (X))
The polymerization component (X) used in Examples and Comparative Examples is as shown in Table 1 below.

[Examples 1 to 12, Comparative Examples 1 to 6]
Active energy ray-curable resin compositions having the compositions shown in Tables 2 and 3 were prepared. The photopolymerization initiator (E) has a concentration of 1.0% by mass of IRGACURE 184 (manufactured by BASF) and 0.1% of IRGACURE 819 (manufactured by BASF) with respect to 100% by mass of the polymerizable component (X). Added at a concentration of 5% by weight.

Several drops of the active energy ray-curable resin composition were dropped on the surface of the stamper, and the active energy ray-curable resin composition was coated while being spread with a polyethylene terephthalate film (A-4300, manufactured by Toyobo Co., Ltd.) having a thickness of 188 μm. Thereafter, the active energy ray-curable resin composition was cured by irradiating ultraviolet rays with an energy of 1000 mJ / cm ² using a high-pressure mercury lamp from the film side. The stamper was released from the film to obtain an article having a fine concavo-convex structure with an average interval of protrusions of 100 nm and a height of 180 nm on the surface. The evaluation results are shown in Tables 2 and 3.

  As is clear from the results in Table 2, the surfaces of the articles obtained in Examples 1 to 12 had good scratch resistance. Moreover, in Examples 2-8, it confirmed that it had the outstanding fingerprint resistance. Furthermore, in Examples 9-11, it confirmed that it had the outstanding water-repellent performance.

  On the other hand, since the articles obtained in Comparative Examples 1 to 4 and 6 did not use the specific vinyl polymer (A), sufficient scratch resistance was not obtained.

  The article obtained in Comparative Example 5 did not have sufficient scratch resistance because the amount of the specific vinyl polymer (A) added was small.

  An article having a fine concavo-convex structure on the surface obtained by curing the active energy ray-curable resin composition of the present invention has both high scratch resistance while maintaining excellent optical performance. It can be used for various displays such as portable game machines and is extremely useful industrially.

12 pores (inverted structure of fine uneven structure)
18 Stamper 20 Rolled Stamper 40 Article

Claims (8)

An article having on the surface a fine concavo-convex structure made of a cured product of an active energy ray-curable resin composition,
The active energy ray-curable resin composition contains a polymerizable component (X) and a photopolymerization initiator (E),
The said polymeric component (X) contains the vinyl polymer (A) which has a repeating unit shown by following formula (1) in 15 mass% or more in the said polymeric component (X);

[In formula (1), R ¹ is an alkylene group having 2 to 8 carbon atoms, R ² is a hydrogen atom or a methyl group, and m is a positive integer].   The article according to claim 1, wherein the fine concavo-convex structure has an average interval between convex portions of not more than a visible light wavelength.   3. The article according to claim 1, wherein the fine concavo-convex structure has a ratio (aspect ratio) of a protrusion height to an average interval between the protrusions of 0.5 to 5. 5.   The article according to any one of claims 1 to 3, wherein the fine uneven structure has a structure in which unevenness is regularly arranged.   The article according to any one of claims 1 to 4, which is an antireflection article. A method for producing an article having a fine relief structure on its surface,
Active energy ray curing containing a polymerizable component (X) containing 15% by mass or more of a vinyl polymer (A) having a repeating unit represented by the following formula (1), and a photopolymerization initiator (E) A method for producing an article, wherein the fine concavo-convex structure is formed using a functional resin composition;

[In formula (1), R ¹ is an alkylene group having 2 to 8 carbon atoms, R ² is a hydrogen atom or a methyl group, and m is a positive integer].   After the active energy ray-curable resin composition is disposed between a base material and a stamper having an inverted structure of the fine uneven structure, the active energy ray-curable resin composition is cured by irradiating active energy rays. The method for manufacturing an article according to claim 6, wherein the fine concavo-convex structure is formed.   The manufacturing method of the antireflection article by the manufacturing method of Claim 6 or 7.

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