JP2013241503A - Polyfunctional urethane (meth)acrylate, active energy ray curing type resin composition and article having fine uneven structure on surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyfunctional urethane (metha) acrylate capable of forming a cured material having excellent scratch resistance and an article having a fine uneven structure having excellent scratch resistance on the surface.SOLUTION: A polyfunctional urethane (metha) acrylate is a reaction product of a compound containing at least the following compound (a1) and compound (a2), wherein an acryl equivalent per one repeating unit composed of one molecule of the compound (a1) and one molecule of the compound (a2) is <240 and the average number of the repeating units is ≥2.0, wherein (a1) is an aliphatic diisocyanate and (a2) is a polyfunctional (meth) acrylate having two hydroxide groups.

Description

  The present invention relates to a polyfunctional urethane (meth) acrylate, an active energy ray-curable resin composition, and an article (an antireflection article or the like) having a fine concavo-convex structure formed using the same on the surface.

  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 exhibits 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 surface with an inverted structure of a fine concavo-convex structure and a substrate, cured by irradiation with active energy rays, and then the stamper is released. A method of forming a cured product layer having a fine concavo-convex structure on the surface, or after filling the active energy ray-curable resin composition between the stamper and the transparent substrate, the stamper is released and activated. A method of transferring a fine concavo-convex structure to an energy ray curable resin composition and then curing the active energy ray curable resin composition having a fine concavo-convex structure on the surface by irradiation with active energy rays.

  Among these, the transferability (formability) of the fine concavo-convex structure is good, the degree of freedom of composition of the surface of the article is high, and continuous production is possible when the stamper is a belt or roll, and the productivity is excellent. Therefore, the method (ii) is attracting attention.

As the active energy ray-curable resin composition used in the method (ii), the following compositions have been proposed.
(1) A photocurable resin composition comprising an acrylate oligomer such as urethane acrylate and a release agent as essential components, and an acrylic resin having a radical polymerizable functional group and a polymerization initiator (Patent Document 1).
(2) A photocurable resin comprising (meth) acrylate such as ethoxylated bisphenol A di (meth) acrylate, a reactive diluent such as N-vinylpyrrolidone, a photopolymerization initiator, and a fluorosurfactant. Composition (patent document 2).
(3) 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 3).

  However, the photo-curable resin composition (1) has a problem that it is easily damaged by rubbing because the cured product has a low crosslinking density.

  In addition, the photo-curable resin composition (2) has a problem that since the polymerizable component has a low molecular weight, the cured product becomes hard and brittle and is easily damaged by rubbing.

  The ultraviolet curable resin composition (3) also has a problem that the cured component becomes hard and brittle because the polymerizable component has a low molecular weight, and is easily damaged by rubbing.

Japanese Patent No. 4156415 Japanese Patent No. 4770354 JP 2000-71290 A

  Therefore, an object of the present invention is to provide an active energy ray-curable resin composition capable of forming a cured product having good scratch resistance, and an article having a fine concavo-convex structure on the surface having good scratch resistance. .

  As a result of intensive studies to solve the above-mentioned problems, the inventors have formulated a cured product having a fine concavo-convex structure excellent in scratch resistance on the surface by blending a polyfunctional urethane (meth) acrylate having a specific structure. The present invention has been completed by finding that it can be formed.

That is, the present invention is a polyfunctional urethane (meth) acrylate which is a reaction product of a compound composition containing at least the compound (a1) and the compound (a2), and comprises one molecule of the compound (a1) and the compound (a2) 1. The acrylic equivalent per repeating unit consisting of molecules is less than 240, and the average number of urethane bonds contained in the polyfunctional urethane (meth) acrylate is 4.0 or more. It is a functional urethane (meth) acrylate.
(A1) Aliphatic diisocyanate.
(A2) A polyfunctional (meth) acrylate having two hydroxyl groups.

  The compound (a1) is preferably hexamethylene diisocyanate.

  The compound (a2) is preferably selected from the group consisting of pentaerythritol di (meth) acrylate, erythritol di (meth) acrylate, and diglycerin di (meth) acrylate.

  The compound (a2) is preferably pentaerythritol di (meth) acrylate.

  The present invention also provides an active energy ray-curable resin composition comprising a radical polymerizable component (X) and a photopolymerization initiator (D), wherein the radical polymerizable component (X) is the above-mentioned polyfunctional urethane ( An active energy ray-curable resin composition comprising a (meth) acrylate.

  It is preferable that the radical polymerizable component (X) also contains polyethylene glycol diacrylate having an oxyethylene group repeating number of 6 to 30.

  Furthermore, the present invention is an article having a fine concavo-convex structure on the surface, wherein the fine concavo-convex structure contacts and cures the active energy ray-curable resin composition with a stamper having an inverted structure of the fine concavo-convex structure on the surface. This is an article having a fine concavo-convex structure formed on the surface.

  The article having the fine uneven structure on the surface is preferably an antireflection article.

  The polyfunctional urethane (meth) acrylate of this invention can form hardened | cured material with favorable abrasion resistance by setting it as an active energy ray curable resin composition. Moreover, the article which has the fine concavo-convex structure on the surface manufactured using this active energy ray-curable resin composition has good scratch resistance of the fine concavo-convex structure.

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, and (meth) acrylamide means acrylamide and / or methacrylamide. Furthermore, active energy rays mean visible light, ultraviolet rays, electron beams, plasma, heat rays (infrared rays, etc.) and the like.

  The present invention relates to a polyfunctional urethane (meth) acrylate, which is a urethane oligomer having a plurality of (meth) acryloyl groups in a molecule, which is useful for producing an article having a fine relief structure on the surface. Specifically, it relates to a polyfunctional urethane (meth) acrylate which is a reaction product of a compound composition containing at least compound (a1): aliphatic diisocyanate and compound (a2): polyfunctional (meth) acrylate having two hydroxyl groups. .

<Multifunctional urethane (meth) acrylate>
The polyfunctional urethane (meth) acrylate of the present invention has an acrylic equivalent of less than 240 per repeating unit formed from the compound (a1) and the compound (a2). By having an acrylic equivalent per repeating unit of less than 240, an article having a fine concavo-convex structure formed using this polyfunctional urethane (meth) acrylate on the surface can secure a sufficient crosslink density and fine concavo-convex Contributes to the maintenance of the structure. Specifically, it is possible to prevent a phenomenon in which protrusions are united when the aspect ratio of the fine concavo-convex structure is high.

  The following two methods can be considered for the synthesis of a urethane oligomer having a plurality of (meth) acryloyl groups in the molecule.

(Method 1)
In this method, a polymer to be a main chain is synthesized first, and a (meth) acryloyl group is introduced later. Specifically, it is as follows.

(Method 1-1)
A polymer is synthesized using a radical polymerizable monomer having a hydroxyl group, and a urethane bond is formed by reacting an isocyanate compound with the hydroxyl group of the side chain. At this time, by using a compound having one isocyanate group and at least one (meth) acryloyl group in one molecule (for example, Karenz (registered trademark) series manufactured by Showa Denko KK) on the side chain ( A (meth) acryloyl group is also introduced.

(Method 1-2)
A polymer is synthesized using a radically polymerizable monomer having a hydroxyl group, and then an isocyanate compound is reacted with the hydroxyl group of the side chain to form a urethane bond. When a urethane bond is formed, a (meth) acryloyl group is introduced into the side chain by simultaneously reacting a diisocyanate compound and a (meth) acrylate having a hydroxyl group.

(Method 1-3)
A polymer is synthesized using a radically polymerizable monomer having an isocyanate group (for example, Karenz (registered trademark) series manufactured by Showa Denko KK), and then a urethane bond is formed by reacting a hydroxyl group with the isocyanate group of the side chain. To do. When a urethane bond is formed, a (meth) acryloyl group is also introduced into the side chain by using a (meth) acrylate having a hydroxyl group.

(Method 2)
A diisocyanate compound is reacted with (meth) acrylate having two or more hydroxyl groups.

  In Method 1, the synthesis is performed in two stages, and a (meth) acryloyl group is introduced in the latter stage. For this reason, it is difficult to introduce a large amount of (meth) acryloyl groups in order to give the necessary crosslink density when the cured product is formed. In addition, since the molecular weight increases and the viscosity becomes very high, it is difficult to handle as a liquid unless it contains a solvent. When transferring the fine concavo-convex structure, it is preferable that there is no solvent, and a certain degree of fluidity is required. Therefore, the polyfunctional urethane (meth) acrylate produced by Method 1 is not preferable.

  In Method 2, synthesis in one step is possible, and a sufficient crosslinking density can be secured depending on the selection of the material to be used. The molecular weight can also be arbitrarily controlled by the charge ratio of each material, and can be handled without a solvent. Therefore, the polyfunctional urethane (meth) acrylate is preferably produced by the method 2.

  The polyfunctional urethane (meth) acrylate produced by Method 2 will be described in detail.

  The polyfunctional urethane (meth) acrylate is composed of the compound (a1) which is an aliphatic diisocyanate and the compound (a2) which is a polyfunctional (meth) acrylate having two hydroxyl groups as essential components, and other components which are added as necessary. As a reaction product with a compound (b) having one or more hydroxyl groups. The polyfunctional urethane (meth) acrylate has a large molecular weight, and an acrylic equivalent per repeating unit formed from the compound (a1) and the compound (a2) is less than 240. When the acrylic equivalent per one repeating unit is less than 240, it is possible to realize the difficulty of bending the protrusion in the fine concavo-convex structure.

  The mass average molecular weight (Mw) of the polyfunctional urethane (meth) acrylate is preferably 1200 or more and 20000 or less, and more preferably 1500 or more and 5000 or less. If the molecular weight is 1200 or more, the effect of improving the scratch resistance of the fine concavo-convex structure due to the large molecular weight is obtained, and if it is 20000 or less, handling with a liquid is possible.

  Moreover, the average number of the urethane bonds which the polyfunctional urethane (meth) acrylate of this invention has is 4.0 or more, and 5.0 or more and 10 or less are preferable. If the average number of urethane bonds is 4.0 or more, it becomes easy to fall within the preferred range of the average molecular weight. Moreover, since the viscosity which can be handled will be sufficient if the average number of urethane bonds is 10 or less, it is preferable.

Compound (a1)
The compound (a1) which is an essential component of the polyfunctional urethane (meth) acrylate is an aliphatic diisocyanate. Examples of the compound (a1) include norbornane diisocyanate, dicyclohexylmethane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-cyclohexane diisocyanate, hexamethylene diisocyanate, and the like.

  Among these, hexamethylene diisocyanate is preferred because it has a low molecular weight in order to keep the acrylic equivalent per repeating unit of polyfunctional urethane (meth) acrylate low.

Compound (a2)
The compound (a2), which is another essential component of the polyfunctional urethane (meth) acrylate, is a polyfunctional (meth) acrylate having two hydroxyl groups. The compound (a2) has two hydroxyl groups, so that the molecular weight can be increased when it is reacted with the compound (a1), so that it has a bifunctional or higher functionality, preferably 2 to 4 functional polyfunctionality. Can be increased.

  In addition, although it is essential that the compound (a2) has two hydroxyl groups, it may contain (meth) acrylate having one hydroxyl group or three or more hydroxyl groups. In that case, the average number of hydroxyl groups in the mixture containing the compound (a2) is preferably 1.3 or more, and more preferably 1.4 or more. If the average number of hydroxyl groups is 1.3 or more, the urethane bond formed in the polyfunctional urethane (meth) acrylate can be 4.0 or more on average. The (meth) acrylate having one hydroxyl group serves to block the hydroxyl groups at both ends of the polyfunctional urethane (meth) acrylate.

  Therefore, the compound (a2) is preferably used in a mixture with (meth) acrylate having one hydroxyl group. In addition, since it will become easy to gelatinize when the polyfunctional urethane (meth) acrylate (A) is synthesize | combined when the (meth) acrylate which has 3 or more of hydroxyl groups is contained, containing in large quantities is not preferable. From this viewpoint, the number of hydroxyl groups in the mixture containing the compound (a2) is preferably 2 or less on average.

  Specifically, examples of the compound (a2) include pentaerythritol di (meth) acrylate, erythritol di (meth) acrylate, dipentaerythritol tetra (meth) acrylate, diglycerin di (meth) acrylate, and ditrimethylolpropane di (meth). An acrylate etc. can be used and these may use 2 or more types together.

  The compound (a2) has an acrylic equivalent of 158 or less, more preferably 125, so that the acrylic equivalent per repeating unit formed from the compound (a1) and the compound (a2) is less than 240. The following is desirable.

  Therefore, many of the bifunctional epoxy acrylates derived from the glycidyl ether type diepoxide compound are not preferable. For example, ethylene glycol diglycidyl ether is a diepoxide compound having a relatively small molecular weight, but a bifunctional epoxy acrylate that is an acrylic acid adduct has an acrylic equivalent of about 159. The acrylic equivalent per repeating unit of the polyfunctional urethane acrylate obtained by reacting this bifunctional epoxy acrylate with hexamethylene diisocyanate is about 243.

  From the above, among the compounds (a2), pentaerythritol di (meth) acrylate, erythritol di (meth) acrylate, diglycerin di (meth) acrylate, and the like are particularly preferable from the viewpoint of the balance between the amount of urethane bonds and the acrylic equivalent.

  When the compound (a2) is actually subjected to the urethane synthesis reaction, it is not necessary to use only a polyfunctional (meth) acrylate having two hydroxyl groups in high purity, and it may have one hydroxyl group or three or more if necessary. It can be used as a mixture with (meth) acrylate.

  Pentaerythritol di (meth) acrylate is a polyfunctional (meth) containing a triester form (one hydroxyl group) and a tetraester form (without a hydroxyl group) by esterifying pentaerythritol with (meth) acryloyl chloride or the like. It can be industrially synthesized relatively easily as a mixture of acrylates, and the ratio of 2 to 4 functional groups of (meth) acryloyl groups can be controlled to some extent. Since the tetraester does not contain a hydroxyl group, it does not react with the compound (a1) and does not contribute to the production of a polyfunctional urethane (meth) acrylate, but is useful as a polyfunctional reactive monomer. There is no problem even if it is contained in a mixture containing (meth) acrylate.

  Erythritol di (meth) acrylate and diglycerin di (meth) acrylate can also be industrially synthesized relatively easily as a mixture of polyfunctional (meth) acrylates containing triesters and tetraesters of erythritol or diglycerin. Furthermore, erythritol and diglycerin each have two primary and secondary alcohols, and it is possible to obtain a di (meth) acrylate body preferentially from the difference in reactivity.

Further, erythritol diacrylate can be synthesized as an acrylic acid adduct of 1,3-butadiene diepoxide.

  The reaction between the compound (a1) and the compound (a2) is a general urethane synthesis reaction, and a known catalyst for urethane synthesis can be used. As the catalyst, dibutyltin laurate is most widely used, but metal complexes such as iron and zinc can also be used.

  About content of a compound (a1) and a compound (a2), it can determine by adjusting the molar ratio of a hydroxyl group and an isocyanate group. Since it is preferable that the isocyanate group is completely consumed in the urethane synthesis reaction, it is preferable that the number of hydroxyl groups at the time of preparation is larger than the number of isocyanate groups. Specifically, the molar ratio of the hydroxyl group to the isocyanate group is preferably adjusted in the range of 1: 0.7 to 1: 0.95.

  Moreover, when using polyfunctional urethane (meth) acrylate as a main structural component of the polymer component (X) of the active energy ray-curable resin composition described below, only the compound (a1) and the compound (a2) are urethanes. The compound (b) having one or more hydroxyl groups may be included as another component during the urethanization reaction of the compound (a1) and the compound (a2). Other components mentioned here include compounds having a hydroxyl group similar to compound (a2) and a (meth) acryloyl group, polyalkylene glycols having hydroxyl groups at both ends, polyesters, polycarbonates, alkanediols, etc. including.

<Active energy ray-curable resin composition>
The active energy ray-curable resin composition of the present invention is a resin composition that undergoes polymerization reaction and cures when irradiated with active energy rays.

  The active energy ray-curable resin composition of the present invention comprises a polymerizable component (X) containing the polyfunctional urethane (meth) acrylate and a photopolymerization initiator (D) as essential components, and, if necessary, ultraviolet rays. Other components such as an absorbent and / or an antioxidant (E) are included.

  The viscosity of the active energy ray-curable resin composition is preferably not too high from the viewpoint of easy flow into the fine concavo-convex structure on the surface of a stamper used in the manufacture of an article having a fine concavo-convex structure described below. That is, the viscosity (25 ° C.) of the active energy ray-curable resin composition is preferably 10,000 mPa · s or less, more preferably 5000 mPa · s or less, and further preferably 2000 mPa · s or less. In the present invention, the viscosity (X ° C.) means a viscosity measured with an E-type viscometer at X ° C.

  However, even if the viscosity (25 ° C.) of the active energy ray-curable resin composition exceeds 10,000 mPa · s, there is a particular problem if the viscosity can be lowered by preheating when contacting with the stamper. Absent. In this case, the viscosity (75 ° C.) of the active energy ray-curable resin composition is preferably 5000 mPa · s or less, and more preferably 2000 mPa · s or less.

  If the viscosity of the active energy ray-curable resin composition is too low, it may be wet and spread during the molding process, which may interfere with the production. Therefore, the viscosity (25 ° C.) is preferably 10 mPa · s or more.

(Radical polymerizable component (X))
The radical polymerizable component (X) contains the above polyfunctional urethane (meth) acrylate as an essential component, and contains other radical polymerizable components (B) as necessary. In the following, in order to avoid confusion, the polyfunctional urethane (meth) acrylate may be expressed as “polyfunctional urethane (meth) acrylate (A)”.

Radical polymerizable component (B)
The other radical polymerizable component (B) is used for imparting various functions to the cured product of the active energy ray-curable resin composition. The functions imparted by the radically polymerizable component (B) include (1) viscosity adjustment of the active energy ray-curable resin composition, (2) surface property control such as hydrophilic / lipophilic, water / oil repellency, 3) Adjustment of the crosslinking density of the cured product of the active energy ray-curable resin composition, and the like.

Other radical polymerizable components (B) include, for example, urethane (meth) acrylates other than polyfunctional urethane (meth) acrylate (A); polyester acrylates; epoxy acrylates; oxyalkylenated polyglycerin poly (meth) Acrylate;
Pentaerythritol tri-tetra (meth) acrylate, dipentaerythritol penta-hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate; oxyalkylenated pentaerythritol tri (meth) acrylate, Oxyalkylenated isocyanuric acid tri (meth) acrylate, oxyalkylenated glycerin tri (meth) acrylate, oxyalkylenated pentaerythritol tetra (meth) acrylate, oxyalkylenated dipentaerythritol penta (meth) acrylate, oxyalkylenated dipentaerythritol Hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexaacrylate; polyethylene glycol Di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, alkanediol di (meth) acrylate, oxyalkylenated alkanediol di (meth) acrylate, oxyalkylenated bisphenol A di (meth) ) Acrylate, oxyalkylenated bisphenol F di (meth) acrylate, oxyalkylenated hydrogenated bisphenol A di (meth) acrylate, neopentyl glycol di (meth) acrylate, oxyalkylenated neopentyl glycol di (meth) acrylate, tricyclo Decandimethanol di (meth) acrylate, dioxane glycol di (meth) acrylate, cyclohexanediol di (meth) acrylate, oxyalkyle Cyclohexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxypivalate, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene, alkyl (meth) acrylate (for example, methyl ( (Meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, etc.) Benzyl (meth) acrylate, (meth) acrylate having an alicyclic structure or saturated cyclic ether structure (for example, isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, adamantyl (meth) acrylate, Dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, etc.), (meth) acrylate having an amino group (for example, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, etc.), hydroxyl group (Meth) acrylate having (for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc.), (meth) acrylamide derivative (for example, (meth) acryloylmorpholine, N, N-dimethyl (meth) acrylamide, etc.), 2-vinylpyridine, 4-vinylpyridine, N-vinylpyrrolidone, N-vinylformamide, vinyl acetate and the like can be used. Here, examples of the oxyalkylenation include oxyethylenation and oxybutylene. Moreover, a radically polymerizable component (B) may be used by 1 type, and may use 2 or more types together. In addition to the (meth) acrylate compounds and vinyl compounds listed here, it is possible to use radically polymerizable components having an allyl group or a vinyl ether group.

  By using a hydrophilic component as the radically polymerizable component (B), the surface of the article made from the active energy ray-curable resin composition, especially oil stains such as fingerprints attached to the fine uneven structure surface is wiped with water. Can be easily removed. Examples of the hydrophilic component include polyethylene glycol diacrylate. The longer the polyethylene glycol chain in the polyethylene glycol diacrylate molecule, the more hydrophilic it can be. However, if the polyethylene glycol chain is too long, the crystallinity becomes high and becomes solid at room temperature, so that the handleability is lowered. Therefore, the molecular weight of the polyethylene glycol chain is preferably about 300 to 1,000, more preferably about 400 to 600.

(Photopolymerization initiator (D))
The photopolymerization initiator (D) 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.

  Examples of the photopolymerization initiator (D) that generates radicals by ultraviolet rays include benzophenone, 4,4′-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, thioxanthones (eg, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone), acetophenones (eg, diethoxyacetophenone, 2-hydroxy-2-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), benzoin ethers (eg, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether), acylphosphine oxides (eg, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc. ), Methylbenzoylformate, 1,7-bisacridinylheptane, 9-phenylacridine and the like. A photoinitiator (D) 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 proportion of the photopolymerization initiator (D) is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and more preferably 0.2 to 100 parts by weight with respect to 100 parts by weight of the radical polymerizable component (X). 3 parts by mass is more preferable. If the ratio of a photoinitiator (D) is less than 0.01 mass part, hardening of an active energy ray-curable resin composition may not be completed, and the mechanical physical property of the article | item which has a fine concavo-convex structure on the surface may be impaired. When the ratio of the photopolymerization initiator (D) exceeds 10 parts by mass, the unreacted photopolymerization initiator (D) remains in the cured product, and acts as a plasticizer, reducing the elastic modulus of the cured product, In some cases, scratch resistance may be impaired. Moreover, it may cause coloring.

(Ultraviolet absorber and / or antioxidant (E))
The active energy ray-curable resin composition of the present invention may further contain an ultraviolet absorber and / or an antioxidant (E).

  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” (both trade names) manufactured by BASF, and “Viosorb110” (trade names) manufactured by Kyodo Pharmaceutical Co., Ltd.

  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” (registered trademark) series manufactured by BASF.

  These ultraviolet absorbers and antioxidants may be used alone or in combination of two or more. As for the ratio of a ultraviolet absorber and / or antioxidant (E), 0.01-5 mass parts is preferable in total with respect to 100 mass parts of radically polymerizable components (X).

(Other ingredients)
The active energy ray-curable resin composition of the present invention includes a surfactant, a release agent, a lubricant, a plasticizer, an antistatic agent, a light stabilizer, a flame retardant, a flame retardant aid, and a polymerization inhibitor, as necessary. , Known additives such as fillers, silane coupling agents, colorants, reinforcing agents, inorganic fillers, impact modifiers and the like may be included.

  Moreover, the active energy ray-curable resin composition of the present invention may contain an oligomer or polymer having no radical polymerizable functional group, a trace amount of an organic solvent, or the like, if necessary.

  Since the active energy ray-curable resin composition of the present invention described above contains a specific polyfunctional urethane (meth) acrylate, a cured product having excellent scratch resistance can be formed. In particular, it is possible to obtain excellent scratch resistance by forming an article having a fine concavo-convex structure using the active energy ray-curable resin composition of the present invention.

<Articles having a fine relief structure on the surface>
The article having the fine concavo-convex structure of the present invention on the surface is a fine concavo-convex structure formed by contacting and curing the active energy ray-curable resin composition of the present invention with a stamper having a reverse structure of the fine concavo-convex structure on the surface. On the surface.

  FIG. 1 is a cross-sectional view showing an example of an article having a fine relief structure on the surface. The article 40 has 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 may be an injection molded body, an extrusion molded body, or a cast molded body. The shape of the substrate 42 may be a sheet shape or a film shape.

  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 of the present invention, and has a fine uneven structure on the surface. The fine concavo-convex structure on the surface of the article 40 when the stamper made of anodized alumina described later is used is formed by transferring the fine concavo-convex structure on the surface of the anodized alumina, and the active energy ray curable resin composition It has the some convex part 46 which consists of hardened | cured material of a thing.

  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 equal to or less than the wavelength of visible light can be an effective anti-reflective means 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 distance exceeds 400 nm, visible light scattering occurs, which is not suitable for optical applications such as antireflection articles. The average interval is more preferably 200 nm or less, and particularly 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. When convex portions are formed using an anodic alumina stamper described later, the average interval between the convex portions is about 100 nm.

  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.

  As for the height of a convex part, when an average space | interval is 100 nm, 80-500 nm is preferable, 120-400 nm is more preferable, 150-300 nm is especially preferable. If the height of the convex portion is 80 nm or more, the reflectance is sufficiently low and the wavelength dependency of the reflectance is small. 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 the distance between the top of the convex portion and the bottom of the concave portion existing between the convex portions when the cross section of the fine concavo-convex structure is observed with an electron microscope at a magnification of 30000 times. It is a value obtained by measuring and averaging the measured values.

  The aspect ratio of the convex portion (height of the convex portion / average interval between the convex portions) is preferably 0.8 to 5, more preferably 1.2 to 4, and particularly preferably 1.5 to 3. If the aspect ratio of the convex portion is 1.0 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 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 particularly 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 is used to provide a fine concavo-convex structure on the surface of an article, and has an inverted structure of the 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 production method include, for example, method (I): a method of forming anodized alumina having a plurality of pores (recesses) on the surface of an aluminum substrate, and method (II): a surface of a stamper substrate. In addition, there is a method of forming an inverted structure of a fine concavo-convex structure by an electron beam lithography method, a laser beam interference method, etc., and the method (I) is preferable because the area can be increased and the production is simple.

As the method (I), a method having the following steps (a) to (f) is preferable:
(A) a step of forming an oxide film on the surface of the aluminum substrate by anodizing the aluminum substrate in an electrolytic solution under a constant voltage;
(B) removing the oxide film and forming pore generation points for anodization on the surface of the aluminum substrate;
(C) After 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 enlarging the diameter of the pores after the step (c);
(E) After step (d), the step of anodizing again in the electrolytic solution to thicken the oxide film; and (f) repeating step (d) and step (e) to form a plurality of pores. A step of obtaining a stamper in which the anodized alumina is formed on the surface of the aluminum substrate.

  Hereafter, each process is demonstrated concretely with FIG.

Step (a):
When the aluminum substrate 10 is anodized, an oxide film 14 having pores 12 on the surface 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 particularly 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.

  As the electrolytic solution, an aqueous solution containing an acid such as sulfuric acid, oxalic acid or phosphoric acid is used.

  When using an oxalic acid aqueous solution as the electrolyte, the concentration of oxalic acid is preferably 0.7 M or less. If the concentration of oxalic acid exceeds 0.7M, the current value during anodic oxidation becomes too high, and the surface of the oxide film may become rough.

  Moreover, it is preferable that the applied voltage (formation voltage) to the anode at the time of anodization is 30 to 60 V. In this formation voltage range, anodized alumina having highly regular pores with a period of about 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 may be a temperature at which anodic oxidation can be satisfactorily performed, preferably 60 ° C. or less, and more preferably 45 ° C. or less. 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 sulfuric acid is used as the electrolytic 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.

  The formation voltage is preferably 25 to 30 V, and an anodic alumina having highly regular pores with a period of about 63 nm can be obtained within this applied voltage range. The regularity tends to decrease whether the formation voltage is higher or lower than this range.

  The temperature of the electrolytic solution may be a temperature at which anodization can be satisfactorily performed, preferably 30 ° C. or less, and more preferably 20 ° C. or less. 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):
The oxide film 14 formed on the surface of the aluminum substrate 10 is once removed. By exposing depressions having regularity formed on the bottom of the oxide film 14 to the surface of the aluminum substrate 10, the regularity of the pores can be improved by setting the pore generation points 16 for anodization.

  Examples of the method for removing the oxide film 14 include a method in which aluminum is not dissolved but is dissolved and removed in a solution that selectively dissolves the oxide film. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

Step (c):
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. The anodization may be performed under the same conditions as in step (a). Deeper pores 12 can be obtained as the anodic oxidation time is lengthened.

Step (d):
A process for expanding the diameter of the pores 12 (hereinafter referred to as a pore diameter expanding process) is performed. The pore diameter expansion process is a process of expanding the diameter of the pores obtained by anodic oxidation by immersing in a chemical solution that dissolves the oxide film. Examples of such a chemical 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):
When the anodic oxidation is performed again, the oxide film 14 is thickened, and the columnar pores 12 having a small diameter extending downward from the bottom thereof are formed deeper. This anodic oxidation 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):
This is a step of repeating the pore diameter expansion process in step (d) and the anodic oxidation in step (e). When step (d) and step (e) are repeated, an oxide film 14 having pores 12 whose diameter continuously decreases in the depth direction from the opening is formed, and anodization is performed on the surface of aluminum substrate 10. A stamper 18 having alumina (aluminum porous oxide film (alumite)) is obtained. In addition, it is preferable to end with the process (d) at the end.

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

  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 has a depth from the outermost surface. A shape that continuously decreases in the direction is preferred.

  The average interval of 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 determined by measuring the interval between adjacent pores 12 (the distance from the center of the pore 12 to the center of the adjacent pore 12) by electron microscope observation, and calculating these values. It is average.

  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 particularly preferably 150 to 300 nm. In addition, the depth of the pore 12 is the bottom of the pore 12 and the top of the convex portion existing between the pores 12 when the cross section of the pore 12 is observed by an electron microscope at a magnification of 30000 times. It is the value which measured the distance between.

  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 particularly preferred.

  The surface of the stamper on which the inverted structure of the fine concavo-convex 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 particularly preferable. Fluoroalkylsilane-based products are known as commercially available fluorine compounds having hydrolyzable silyl groups. For example, KBM-7803 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), MRAF (trade name, Asahi Glass) Ltd.), Durasurf DS-1100, DS-2100 series (trade name, manufactured by Harves Co., Ltd.), OPTOOL DSX (trade name, manufactured by Daikin Industries, Ltd.), Novec 1720 (trade name, manufactured by Sumitomo 3M Co., Ltd.), Fluorosurf FS-2050 series (trade name, manufactured by Fluoro Technology Co., Ltd.)

(Manufacture of articles having a fine relief structure on the surface)
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 stamper 20 and the nip roll 26 whose nip pressure is adjusted by the pneumatic cylinder 24, and the active energy ray curable resin composition is used as a base. It extends uniformly between the material 42 and the roll-shaped stamper 20 and simultaneously fills the concave portions of the fine concavo-convex 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 to cure the active energy ray curable resin composition. Then, the cured resin layer 44 is formed by inverting and transferring the fine uneven structure on the surface of the roll stamper 20.

  The base material 42 having the cured resin layer 44 formed on the surface is peeled from the roll-shaped stamper 20 by the peeling roll 30 to obtain the article 40 having a fine uneven structure on the surface.

As the active energy ray irradiation device 28, a high-pressure mercury lamp, a metal halide lamp, or the like is preferable, and the amount of light irradiation energy in this case varies depending on the type and blending ratio of the radical polymerizable component (X) and the photopolymerization initiator (D). However, it is preferable that the total is about 100 to 10,000 mJ / cm ² .

  The base material 42 used in this method is 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)
Articles having the fine concavo-convex structure of the present invention on the surface are antireflection articles (antireflection films, antireflection films, etc.), optical articles such as optical waveguides, relief holograms, lenses, polarization separation elements; 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.

  In the article having the fine concavo-convex structure of the present invention described above on the surface, an active energy ray-curable resin composition containing the polyfunctional urethane (meth) acrylate of the present invention as a main component of the polymerizable component (X) is provided. Since it is used, the fine concavo-convex structure has high scratch resistance and good fingerprint wiping properties.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Measurement of viscosity)
An E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-25 type viscometer (trade name)) was used and measured at 25 ° C.

(Evaluation of scratch resistance)
Using a reciprocating abrasion tester (“SHiDON TRIBOGEAR TYPE-30S” (trade name) manufactured by Shinto Kagaku Co., Ltd.), the surface on which the fine uneven structure of the article is formed is 2 cm square steel wool (manufactured by Nippon Steel Wool Co., Ltd.). The surface of the article was scratched by applying a load of 100 g to Bonster # 0000 (trade name) and reciprocating 10 times at a reciprocating distance of 30 mm and a head speed of 30 mm / sec. The article after abrasion is attached to one side of a 2.0 mm thick black acrylic board (manufactured by Mitsubishi Rayon Co., Ltd., Acrylite (registered trademark)) with the abrasion surface up, and is held over a fluorescent lamp indoors. It observed visually and evaluated by the following reference | standard.
○: There are few scratches that can be confirmed, and it is hardly visible when viewed from an oblique direction.
(Triangle | delta): There exists a flaw which can be confirmed and it looks a little white also from diagonally.
X: There are many scratches that can be confirmed, and the entire scratches appear white.

(Evaluation of fingerprint wiping property)
An artificial fingerprint liquid (prepared according to the description of JIS K2246: 2007) was adhered to the surface of the fine concavo-convex structure to produce a fingerprint-adhered article. Next, the fingerprint on the fingerprint-adhered article was wiped in one direction up to 10 times with a wiper (Dao Paper Co., Ltd., Erière Pro Wipe (trade name)) impregnated with 1.0 cc of tap water. The fingerprint surface was visually confirmed after each wiping and evaluated according to the following criteria.
○: Fingerprints were completely removed by wiping twice or less.
Δ: Fingerprints were completely removed by wiping 3 to 10 times.
X: Fingerprints remained even after wiping 10 times.

(Evaluation of releasability)
The surface of an article having a fine concavo-convex structure on the surface was observed by an electron microscope to see whether the tip of the protrusion was chipped and the shape of the fine concavo-convex structure of the stamper could be transferred. In addition, the following criteria evaluated.
○: There is almost no chipping and it is good.
X: There are chips and the uneven structure is uneven.

Production Example 1 (Production of stamper)
Step (a):
An aluminum plate having a purity of 99.99% was subjected to feather polishing and electrolytic polishing in a perchloric acid / ethanol mixed solution (1/4 volume ratio), and a mirror-finished aluminum plate was subjected to a 0.3M oxalic acid aqueous solution. Anodization was performed for 30 minutes under the conditions of DC 40V and temperature 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 from which the oxide film was removed in the step (b) was anodized for 30 seconds in a 0.3 M oxalic acid aqueous solution under conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (d):
The aluminum plate obtained by the step (c) and having an oxide film having pores on the surface 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 that had been subjected to pore diameter expansion treatment in step (d) was again anodized in a 0.3 M oxalic acid aqueous solution under the conditions of a direct current of 40 V and a temperature of 16 ° C. for 30 seconds.

Step (f):
Step (d) and step (e) are repeated a total of 4 times, and finally step (d) is performed, and anodized alumina having pores having a substantially conical shape with an average interval of 100 nm and a depth of 180 nm is formed on the surface. Got a stamper.

  After the obtained stamper was washed with deionized water, the moisture on the surface was removed by air blow, and OPTOOL DSX (trade name, manufactured by Daikin Industries, Ltd.) was used as a diluent DURA so that the solid content was 0.1% by mass. A stamper treated with a release agent was obtained by immersing in a solution diluted with Surf HD-ZV (trade name, manufactured by Harves Co., Ltd.) for 10 minutes, lifting from the solution and air-drying for 20 hours.

Example 1
(Synthesis of polyfunctional urethane (meth) acrylate (A-1))
In a 5-liter four-necked flask, 500 g of pentaerythritol acrylate (2- to 4-functional mixture, hereinafter abbreviated as PETA) having a hydroxyl value of 157 mgKOH as compound (a2), 0.18 g of dibutyltin laurate as a catalyst and polymerization inhibition As an agent, 0.62 g of 3,5-dibutyl-4-hydroxytoluene was mixed and heated to 70 ° C. while stirring. Subsequently, 117 g of hexamethylene diisocyanate (HDI) was added dropwise as the compound (a1) over 2 hours, and the temperature of the reaction solution was maintained at 70 ° C. during the dropwise addition. After stirring while maintaining at 70 ° C. for 2 hours from the end of dropping, it was confirmed by isocyanate titration that the residual isocyanate was below the detection limit, and polyfunctional urethane (meth) acrylate (A-1) was obtained. In addition, the isocyanate group of HDI with respect to the hydroxyl group in PETA was about 1.

  The polyfunctional urethane (meth) acrylate (A-1) obtained here was analyzed for polystyrene-reduced mass average molecular weight (Mw) using gel permeation chromatography, and the mass average molecular weight (Mw) was 1761. . The Mw is calculated from the peak of the urethane (meth) acrylate part excluding the peak of pentaerythritol tetraacrylate contained. The average number of urethane bonds in the polyfunctional urethane (meth) acrylate (A-1) calculated from this molecular weight was 6.8.

Examples 2-3 and Comparative Example 1
(Synthesis of polyfunctional urethane (meth) acrylate (A-2) to (A-4))
PETA was used as the compound (a2), and HDI was used as the compound (a1). By changing the composition ratio of 2 to 4 functional groups in the PETA to be used and setting the charging ratio of the compound (a1) and the compound (a2) so that the number of moles of hydroxyl groups is equal to or greater than the number of moles of isocyanate groups, Polyfunctional urethane (meth) acrylates (A-2) to (A-4) having the molecular weight shown in 1 and the average number of urethane bonds were synthesized.

  As the polyfunctional urethane (meth) acrylate of the radical polymerizable component (X) of the active energy ray-curable resin composition, the polyfunctional urethane (meth) acrylate (A-1) prepared in Examples 1 to 3 and Comparative Example 1 above. ) To (A-4) and urethane acrylate UA-306H (trade name, from PETA and HDI) having an average number of urethane bonds commercially available from Kyoeisha Chemical Co., Ltd., UA-306I (product) Name, from PETA and isophorone diisocyanate (IPDI)) and UA-306T (trade name, from PETA and toluene diisocyanate (TDI)). In addition, urethane acrylate UA-306H, I, and T were shown as (A-5)-(A-7) in the said Table 1, respectively.

(Radical polymerizable component (B))
The compounds shown in Table 2 below were used as the radical polymerization component (B) of the radical polymerizable component (X) of the active energy ray-curable resin composition.

(Photopolymerization initiator (D))
As a photopolymerization initiator (D) of the active energy ray-curable resin composition, IRGACURE 184 and IRGACURE 819 (both are trade names, manufactured by BASF) are each 1. 0 parts by mass and 0.5 parts by mass were used.

Example 4
70 parts by mass of polyfunctional urethane (meth) acrylate (A-1), 30 parts by mass of PEGDA-14E and 1.5 parts by mass of photopolymerization initiator (D) are mixed to prepare an active energy ray-curable resin composition. did.

After dropping several drops of the active energy ray-curable resin composition on the surface of the stamper and covering with a triacetyl cellulose film (manufactured by Fuji Film Co., Ltd., TAC film TD80ULM (trade name)) having a thickness of 80 μm, the film is coated. From the side, ultraviolet rays were irradiated at 2000 mJ / cm ² using a high-pressure mercury lamp and cured. 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. Each of the above evaluations was performed on the obtained article, and the results obtained are shown in Table 3.

[Examples 5 to 9, Comparative Examples 2 to 5]
Except for changing the composition of the active energy ray-curable resin composition to the composition shown in Table 3, an article having a fine concavo-convex structure on the surface was obtained in the same manner as in Example 4 and evaluated in the same manner as in Example 4 below. The obtained evaluation results are shown in Table 3.

  As is apparent from the results in Table 3, the articles obtained in Examples 4 to 9 had good scratch resistance and fingerprint wiping properties because they used the polyfunctional urethane (meth) acrylate of the present invention. .

  On the other hand, in Comparative Examples 2 and 3, since the polyfunctional urethane (meth) acrylate used had few urethane bonds, the obtained articles did not have sufficient scratch resistance. Moreover, in Comparative Example 4, since the used polyfunctional urethane (meth) acrylate (A-6) was synthesized using IPDI as the compound (a1), the acrylic equivalent per repeating unit was 233. The scratch resistance was not obtained. In addition, the fingerprint wiping property was also lowered because the structure derived from IPDI impaired the hydrophilicity.

  In Comparative Example 5, since the polyfunctional urethane (meth) acrylate (A-7) was synthesized using TDI, which is an aromatic diisocyanate, as the compound (a1), the projections of the fine concavo-convex structure of the article obtained from the structure were obtained. It was hard and brittle, and sufficient scratch resistance was not obtained. Moreover, since the structure derived from TDI impaired hydrophilicity, the fingerprint wiping property also decreased.

  The polyfunctional urethane (meth) acrylate of the present invention is obtained by curing when used as the main component of the radically polymerizable component of the active energy ray-curable resin composition used in the manufacture of an article having a fine relief structure on the surface. An article having a fine concavo-convex structure on the surface achieves both good fingerprint wiping and high scratch resistance while maintaining excellent optical performance. Articles having a fine concavo-convex structure formed by curing the active energy ray-curable resin composition according to the present invention on the surface of a transparent substrate are used in various displays such as televisions, mobile phones, and portable game machines. Available.

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

Claims (8)

A polyfunctional urethane (meth) acrylate which is a reaction product of a compound containing at least the compound (a1) and the compound (a2), and per repeating unit composed of one molecule of the compound (a1) and one molecule of the compound (a2) And the average number of urethane bonds contained in the polyfunctional urethane (meth) acrylate is 4.0 or more:
(A1) Aliphatic diisocyanate.
(A2) A polyfunctional (meth) acrylate having two hydroxyl groups.   The polyfunctional urethane (meth) acrylate according to claim 1, wherein the compound (a1) is hexamethylene diisocyanate.   The compound (a2) is selected from the group consisting of pentaerythritol di (meth) acrylate, erythritol di (meth) acrylate, and diglycerin di (meth) acrylate. The polyfunctional urethane (meth) acrylate described in 1.   The polyfunctional urethane (meth) acrylate according to any one of claims 1 to 3, wherein the compound (a2) is pentaerythritol di (meth) acrylate.   An active energy ray-curable resin composition comprising a radical polymerizable component (X) and a photopolymerization initiator (D), wherein the radical polymerizable component (X) is defined in any one of claims 1 to 5. An active energy ray-curable resin composition comprising the polyfunctional urethane (meth) acrylate as described.   6. The active energy ray-curable resin composition according to claim 5, wherein the radical polymerizable component (X) contains polyethylene glycol diacrylate having a repeating number of oxyethylene groups of 6 to 30.   An article having a fine concavo-convex structure on the surface, wherein the fine concavo-convex structure contacts the active energy ray-curable resin composition according to claim 5 or 6 with a stamper having an inverted structure of the fine concavo-convex structure on the surface, An article having a fine concavo-convex structure on the surface, which is formed by curing.   8. An article having a fine concavo-convex structure on a surface thereof according to claim 7, which is an antireflection article.

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