JP2007334134A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film in which interference fringes are not conspicuous, minimum reflectivity is low and which is excellent in transparency, steel wool resistance, an antistatic property and a curling property. <P>SOLUTION: The antireflection film has a hard coat layer on a base material film consisting of biaxially stretched poly(ethylene terephthalate) and further has a low refractive index layer thereon. Thickness of the hard coat layer is 0.5 to 5μm and the hard coat layer is formed by compounding 100 mass part of ionization radiation curing resin containing multi-functional (meth)acrylate having two or more (meth)acryloyl groups in a molecule with 20 to 200 mass part of antimony pentoxide and then curing. Further an easily adhesive layer with a refractive index between 1.56 and 1.62 is provided between the base material film and the hard coat layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antireflection film, and in particular, relates to an antireflection film in which interference fringes are not conspicuous, the minimum reflectance is low, and transparency, steel wool resistance, antistatic properties, and curl properties are excellent. It is.

Currently, an antireflection film having both an anti-scratch performance and an antireflection performance is often attached to the surface of a display such as a liquid crystal display device, a plasma display panel, a personal computer, a television, and a touch panel. Such an antireflection film has a structure in which a hard coat layer, a high refractive index layer, and a low refractive index layer are sequentially provided on a base film.
However, the conventional antireflection film has a problem that the interference fringes are conspicuous.
When white light hits a transparent thin film, interference fringes cause interference between the light reflected from the surface of the thin film and the light that has entered the thin film and reflected from the back side of the film, and a partial iris color can be seen. It is a phenomenon. This is because the strengthening wavelength varies depending on the viewing direction. This phenomenon is not only difficult to see for the user but may give an unpleasant impression, and there is a need for improvement.

In order to solve this problem, for example, Patent Document 1 discloses a medium refractive index layer having a refractive index of 1.5 to 1.7 on a transparent base film, and a high refractive index of 1.6 to 1.8. A refractive index layer and a low refractive index layer made of a refractive index material lower than that of the high refractive index layer are laminated in this order from the transparent substrate film side, and are fine particles having a refractive index of 1.5 to 1.8. An antireflection hard coat sheet in which fine particles having a difference from the refractive index of the high refractive index layer within ± 0.1 are dispersed and contained in the high refractive index layer, and the surface of the high refractive index layer forms a fine uneven structure. Proposed. However, if fine particles are dispersed in the coat layer to form an uneven structure on the surface, the sharpness of the image is lowered.
Patent Document 2 discloses a transparent polymer film as a transparent hard coat film in which interference fringes due to thickness unevenness of the transparent hard coat film are not conspicuous while maintaining high hard coat properties and perspective resolution. A transparent hard coat film having a transparent hard coat film provided on at least one surface of the polymer film and having a b ^* value of 0.5 or less in the L ^* a ^* b ^* color system has been proposed. . However, the color tone of the hard coat film is selected according to each application, and its application is limited when the b ^* value is limited to 0.5 or less.
Further, Patent Document 3 discloses an optical material having a hard coat layer in which a hard coat layer is formed using an ionizing radiation curable resin containing metal oxide ultrafine particles having good dispersibility, and the generation of interference fringes is prevented. As a method for producing a plastic film, a method of forming a silicon oxide film, dispersing metal oxide ultrafine particles surface-treated with a coupling agent in an ionizing radiation curable resin, and coating the resin on a base plastic film Has been proposed. However, the process of forming a silicon oxide film on metal oxide ultrafine particles having a particle size of several tens of nm, surface-treating with a coupling agent, and dispersing in a resin is complicated and inevitably increases the cost.
Note that the problem of interference fringes has not been completely solved by the above-described prior art.

On the other hand, an antireflection film having a simplified layer structure is required from the viewpoint of economy and the like. For example, an antireflection film having a structure in which a hard refractive index layer also has a role of a high refractive index layer and a low refractive index layer provided thereon is advantageous in that the number of layers is reduced and the manufacturing cost is reduced. At the present time, no known interference fringe problem has been solved, the minimum reflectance is low, and steel wool resistance, antistatic properties and curling properties are not known.
JP 2003-75605 A JP 2003-334891 A Japanese Patent No. 3383039

  An object of the present invention is an antireflection film having a structure in which a hard refractive index layer also has a role of a high refractive index layer and a low refractive index layer provided thereon, and interference fringes are not particularly noticeable, and the lowest reflectance The object of the present invention is to provide an antireflection film that is low in transparency and excellent in transparency, steel wool resistance, antistatic properties and curling properties.

  As a result of intensive studies to solve the above problems, the present inventors have found that an easy-adhesive material layer having a specific refractive index, a specific thickness and material on a base film made of biaxially stretched polyethylene terephthalate It has been found that the above problem can be solved by sequentially providing a hard coat layer having a structure, and the present invention has been completed based on this finding.

That is, the present invention is as follows.
(1) An antireflection film having a hard coat layer on a base film made of biaxially stretched polyethylene terephthalate, and further having a low refractive index layer on the hard coat layer,
The hard coat layer has a thickness of 0.5 to 5 μm;
The hard coat layer is blended with 100 parts by mass of ionizing radiation curable resin containing polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, and 20 to 200 parts by mass of antimony pentoxide, It is formed by curing this,
An antireflection film, wherein an easy-adhesive layer is provided between the base film and the hard coat layer, and a refractive index of the easy-adhesive layer is 1.56 to 1.62.

  (2) The reflection according to claim 1, wherein 5 to 20 parts by mass of a polymer having an unsaturated double bond copolymerizable at a terminal is further added to 100 parts by mass of the ionizing radiation curable resin. Prevention film.

  (3) The antireflection film as described in (1) above, wherein the polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule is dipentaerythritol hexaacrylate.

  (4) The antireflection film as described in (1) above, wherein the antimony pentoxide has an average particle size of 5 to 100 nm.

  (5) The antireflective film according to claim 1, wherein the refractive index of the hard coat layer is 1.51 to 1.61.

  (6) The antireflective film as described in (1) above, wherein the low refractive index layer contains 20 to 100 parts by mass of hollow silica particles in 100 parts by mass of a matrix component having a silicone skeleton.

  (7) The antireflection film as described in (6) above, wherein the hollow silica particles have an average particle diameter of 5 to 100 nm.

(8) The surface resistivity is 1.0 × 10 ¹² Ω / sq. The antireflection film as set forth in any one of (1) to (7), which is:

  (9) The antireflection film as described in any one of (1) to (8) above, wherein the total light transmittance is 90% or more.

  The antireflection film of the present invention has a configuration in which an easy-adhesive material layer having a specific refractive index and a hard coat layer having a specific thickness and material configuration are sequentially provided on a base film made of biaxially stretched polyethylene terephthalate. Therefore, even if it has a simple configuration in which a hard coating layer has a role of a high refractive index layer and a low refractive index layer provided thereon, interference fringes are not particularly noticeable, and the minimum reflectance is low. An antireflection film excellent in transparency, steel wool resistance, antistatic property and curling property can be provided.

Hereinafter, the present invention will be described in more detail.
(Base film)
The base film used in the present invention is made of biaxially stretched polyethylene terephthalate having transparency. A biaxially stretched polyethylene terephthalate film is preferably used because of its good mechanical strength and dimensional stability.
The refractive index of the base film is usually 1.64 to 1.66. In addition, the refractive index as used in the field of this invention is the value measured using the Abbe refractometer according to JISK7142. Moreover, the thickness of a base film is 20-250 micrometers, for example.

(Hard coat layer)
The hard coat layer in the present invention must satisfy the following requirements (1) and (2).
(1) The thickness is 0.5-5 μm.
If thickness is less than 0.5 micrometer, pencil hardness will fall and steel wool resistance will also fall. When the thickness exceeds 5 μm, the interference fringe prevention effect is not exhibited. A preferred thickness is 0.8 to 4.0 μm, and a more preferred thickness is 1.2 to 3.0 μm.

  (2) An ionizing radiation curable resin containing polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, 20 to 200 parts by mass of antimony pentoxide, and optionally copolymerized at the terminal It is formed by blending 5 to 20 parts by mass of a polymer having a possible unsaturated double bond and curing it.

  As polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Examples include pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol di (meth) acrylate, trimethylolpropane di (meth) acrylate, and epoxy acrylate. Preferable specific examples include pentaerythritol triacrylate, dipentaerythritol hexa (meth) acrylate, and dipentaerythritol pentaacrylate. Among them, dipentaerythritol hexa (meth) acrylate is particularly preferable. These polyfunctional (meth) acrylates may be used alone or in combination of two or more.

Antimony pentoxide preferably has an average particle size of 5 to 100 nm. By having this average particle diameter, the interference fringe prevention effect and transparency are enhanced.
A more preferable average particle size is 10 to 70 nm, and a particularly preferable average particle size is 15 to 50 nm.
Antimony pentoxide preferably has a pyrochlore structure. What has such a pyrochlore structure has the property that the electroconductivity by proton conduction is high. The pyrochlore structure is an octahedron formed of six oxygen atoms and OH groups centered on antimony atoms, as described in Journal of Chemical Society of Japan, No. 4, P. 488, 1983. A skeleton structure formed by sharing the vertices of these octahedrons.

  Examples of the polymer having an unsaturated double bond copolymerizable at the terminal include terminal methacrylate polymethyl methacrylate, terminal styryl polymethacrylate, terminal methacrylate polystyrene, terminal methacrylate polyethylene glycol, terminal methacrylate acrylonitrile-styrene copolymer, terminal methacrylate styrene. -A methyl methacrylate copolymer etc. can be mentioned, The mass mean molecular weight has preferable 5000-10000. Examples of commercially available polymers having an unsaturated double bond copolymerizable at the terminal include macromonomers AA-6, AS-6S, AN-6S, AW-6S (manufactured by Toagosei Co., Ltd.), and the like. Can do.

In the present invention, the hard coat layer is composed of 100 parts by mass of ionizing radiation curable resin containing polyfunctional (meth) acrylate having two or more (meth) acryloyl groups, 20 to 200 parts by mass of antimony pentoxide, depending on necessity. It forms using the composition which mix | blended 5-20 mass parts of polymers which have an unsaturated double bond copolymerizable at the terminal. When the blending ratio of antimony pentoxide is less than 20 parts by mass, the effect of preventing interference fringes is not exhibited. In addition, no antistatic effect is exhibited. When the blending ratio of antimony pentoxide exceeds 200 parts by mass, the effect of preventing interference fringes is not exhibited. If the polymer having an unsaturated double bond copolymerizable at the terminal is less than 5 parts by mass, the curling property is somewhat inferior, and if it exceeds 20 parts by mass, the haze is increased and the transparency is lowered.
Further preferable blending ratio is 45 to 140 parts by mass of antimony pentoxide and copolymerizable to the terminal with respect to 100 parts by mass of ionizing radiation curable resin containing polyfunctional (meth) acrylate having two or more (meth) acryloyl groups. 5 to 15 parts by mass of a polymer having an unsaturated double bond.

  A hard-coat layer can be formed by apply | coating the said composition as a coating material on a base film, drying, and making it harden | cure by ionizing radiation irradiation. There is no particular limitation on the ionizing radiation, and examples thereof include an electron beam, radiation, and ultraviolet rays. Among ionizing radiations, ultraviolet rays are particularly suitable because they are simple in equipment and easy to handle. By irradiating with ionizing radiation and crosslinking, a coating film having a pencil hardness of H or higher as defined in JIS K 5400 can be formed.

  When the ionizing radiation is ultraviolet, a photopolymerization initiator is usually added. There is no restriction | limiting in particular as a photoinitiator, For example, Irgacure 184,907,651,1700,1800,819,369 (made by Ciba Specialty Chemicals), Darocur 1173 (made by Merck), Ezacure KIP150, TZT ( Nippon Siebel Hegner), Lucillin TPO (BASF), Kayacure BMS (Nippon Kayaku) and the like.

  Of course, the composition can be used in combination with various additives as required.

  The obtained hard coat layer preferably has a refractive index of 1.51 to 1.61. Within this range of refractive index, the effect of preventing interference fringes is further improved. A more preferable refractive index is 1.54 to 1.61.

(Easily adhesive layer)
In the antireflection film of the present invention, an easy-adhesive layer is provided between the base film and the hard coat layer for the purpose of improving the adhesion between them and improving the interference fringe prevention effect.
The easy-adhesive layer in the present invention needs to have a refractive index of 1.56 to 1.62. If the refractive index is out of this range, the interference fringe prevention effect does not appear. A more preferable refractive index is 1.58 to 1.61.
The material of the easy-adhesive layer is not particularly limited as long as it satisfies the above refractive index range, is transparent, and improves the adhesion between the base film and the hard coat layer. For example, an acrylic resin or a polyester resin , Urethane resins and copolymers thereof. Although the thickness of an easily adhesive layer is not specifically limited, 0.03-0.30 micrometer is preferable and 0.05-0.20 micrometer is more preferable. The easy adhesive layer can be provided on the base film by a known coating technique.

(Low refractive index layer)
The low refractive index layer in the present invention is not particularly limited, and a known low refractive index layer can be appropriately employed. For example, a layer formed by coating fine particles, such as polysiloxane, hollow silica, magnesium fluoride, and fluororesin, which are low refractive index materials, in a matrix component that can form a low refractive index layer, to form a paint. Can be.
In the present invention, a material having a silicone skeleton is preferably used as the matrix component, and more preferably a low refractive index layer containing 20 to 100 parts by mass of hollow silica particles in 100 parts by mass of the matrix component. According to such a low refractive index layer, an antireflection film exhibiting excellent alkali resistance without lowering the minimum reflectance can be provided.

As a matrix component having a silicone skeleton, a hydrolyzable organosilicon compound can be used. Specifically, for example, a partial hydrolyzate of alkoxysilane is suitably used by adding water or an acid or alkali as a catalyst to a mixture of alkoxysilane and alcohol.
The hydrolyzable organic silicon compounds of the general formula _{R n Si (OR ') 4} -n [R, R': an alkyl group, an aryl group, a vinyl group, an acrylic group, a hydrocarbon group such as, n = 0, 1 2 or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used. Through a process in which the hydrolysis / partial condensate of alkoxysilane is condensed and cured by heating, a cured film having a main skeleton composed of siloxane bonds is formed.

  Furthermore, as the matrix component having a silicone skeleton, a disilane compound having a structure of the following formula (1) or a (partial) hydrolyzate thereof is preferable.

^{_{X m R 1 3-m Si}} -Y-SiR 1 3-m X m (1)
Wherein R ¹ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, Y is a divalent organic group containing one or more fluorine atoms, X is a hydrolyzable group, and m is 1, 2 or 3. .)

Examples of Y include the following structures.
_{-C 2 H 4 - (CF 2} ) n -C 2 H 4 -
_{-C 2 H 4 -CF (CF 3} ) - (CF 2) n -CF (CF 3) -C 2 H 4 -
_{-C 2 H 4 -CF (C 2} F 5) - (CF 2) n -CF (C 2 F 5) -C 2 H 4 -
_{-C 2 H 4 -CF (CF 3} ) CF 2 -O (CF 2) n O-CF 2 CF (CF 3) -C 2 H 4 -
(However, n is 2-20.)
_{-C 2 H 4 -C 6 F 10} -C 2 H 4 -
_{-C 2 H 4 -C 6 F 4} -C 2 H 4 -

Specific examples of the hydrolyzable group X include a halogen atom such as Cl and an organooxy group represented by OR ² (R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms). The silane compound of the group is preferable because it is easy to handle and the reaction during hydrolysis is easy to control.

Preferred disilane compounds include
_{(CH 3 O) 3 Si-} C 2 H 4 - (CF 2) 4 -C 2 H 4 -Si (OCH 3) 3
_{(CH 3 O) 3 Si-} C 2 H 4 - (CF 2) 6 -C 2 H 4 -Si (OCH 3) 3
_{(CH 3 O) 3 Si-} C 2 H 4 - (CF 2) 8 -C 2 H 4 -Si (OCH 3) 3
_{(C 2 H 5 O) 3} Si-C 2 H 4 - (CF 2) 4 -C 2 H 4 -Si (OC 2 H 5) 3
_{(C 2 H 5 O) 3} Si-C 2 H 4 - (CF 2) 6 -C 2 H 4 -Si (OC 2 H 5) 3
Etc.

Further, an organosilicon compound containing a fluorine atom-substituted organic group represented by the following formula (2) or a (partial) hydrolyzate thereof may be used in combination with the disilane compound of the formula (1).
Rf-SiX ₃ (2)
(In the formula, Rf is a monovalent organic group containing one or more fluorine atoms, and X is a hydrolyzable group.)
Rf preferably contains 1 or more, preferably 3 to 25, particularly preferably 3 to 17, fluorine atoms. More preferable Rf can be exemplified as follows.
CF ₃ C ₂ H ₄ −
CF ₃ (CF ₂ ) ₃ C ₂ H ₄ −
CF ₃ (CF ₂ ) ₇ C ₂ H ₄ −
X is as described above.

  When the disilane compound having the structure of the formula (1) and the organosilicon compound represented by the formula (2) are mixed and used, the content of the disilane compound may be 60% by mass or more and less than 100% by mass. desirable. In the present invention, a mixture obtained by cohydrolyzing a mixture of a disilane compound and an organosilicon compound may be used.

  As the matrix component having the silicone skeleton, commercially available ones can be used, and examples thereof include X-12-2510 manufactured by Shin-Etsu Chemical Co., Ltd.

  The hollow silica particles are particles having an outer shell layer mainly composed of silica and having a porous or hollow interior. The average particle diameter of the hollow silica particles is preferably 5 to 100 nm, and more preferably 10 to 80 nm.

  As described above, the hollow silica particles are preferably included in an amount of 20 to 100 parts by mass with respect to 100 parts by mass of the matrix component having a silicone skeleton in the present invention, and more preferably, 100 parts by mass of the matrix component having a silicone skeleton. The hollow silica particles are 30 to 80 parts by mass. What is marketed can be utilized for the said composition, for example, the catalyst chemical industry Co., Ltd. make and ELCOM P-5012 can be utilized.

  Furthermore, various additives may be added to the low refractive index layer in the present invention for the purpose of adjusting physical properties such as hardness, scratch resistance, and conductivity of the coating.

  Examples of the organic solvent suitable for use in the coating material for forming the low refractive index layer include alcohols such as methanol, isopropyl alcohol, ethylene glycol, butanol and ethylene glycol monopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, Aromatic hydrocarbons such as toluene and xylene, amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, esters such as ethyl acetate, butyl acetate and γ-butyrolactone, ethers such as tetrahydrofuran and 1,4-dioxane And β-diketones such as acetylacetone and ethyl acetoacetate, and β-ketoesters.

  The refractive index of the low refractive index layer is preferably 1.28 to 1.50, more preferably 1.30 to 1.45. The thickness of the low refractive index layer is preferably 40 to 300 nm, and more preferably 60 to 150 nm.

The antireflection film of the present invention preferably has a total light transmittance of 90% or more, and more preferably 92% or more. The total light transmittance can be measured according to JIS K 7361-1. When the total light transmittance is less than 90%, the transparency is slightly inferior, and when used as an antireflection film for a display, the sharpness of the image may be lowered.
The antireflection film of the present invention has a surface resistivity of 1.0 × 10 ¹² Ω / sq. Or less, preferably 1.0 × 10 ¹⁰ Ω / sq. More preferably, it is as follows.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these examples.

Example 1
On a biaxially stretched polyethylene terephthalate film (refractive index of 1.65) having a thickness of 100 μm, a water-dispersible polyester-based resin is applied as an easy-adhesive layer at a thickness of 0.1 μm (refractive index of 1.60). The coating composition for forming a hard coat layer having the following composition was applied to a dry film thickness of 2.5 μm and dried. Subsequently, the coating was cured by irradiating ultraviolet rays with a high pressure mercury lamp to form a hard coat layer (refractive index 1.57).
Next, a low refractive index layer-forming coating material A having the following composition was applied on the hard coat layer so as to have a dry film thickness of 70 nm (refractive index of 1.39 of the low refractive index layer), and dried. An antireflection film was produced.

(Hard coat layer forming paint)
・ Ionizing radiation curable resin 100 parts by mass Dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd. 6-functional acrylic UV curable resin, solid content 100%)
・ 333 parts by mass of antimony pentoxide sol
(Solid content 100 parts by mass)
(Catalytic Chemical Industries, ELCOM RK-1022SBV, solid content 30%,
Solvent is denatured alcohol)
-Polymer having an unsaturated double bond copolymerizable at the terminal 20 parts by mass
(9 mass parts solid content)
(Macromonomer AA-6 manufactured by Toa Gosei Co., Ltd.
Terminal methacrylate polymethyl methacrylate, molecular weight 6000,
(45% solid content, diluted with toluene)
・ 7 parts by weight of photopolymerization initiator (Irgacure (IR) 184, manufactured by Ciba Specialty Chemicals)
-Photopolymerization initiator 1 part by mass (Irgacure (IR) 907 manufactured by Ciba Specialty Chemicals)
・ Solvent 120 parts by mass (methyl ethyl ketone (MEK) / propylene glycol monomethyl ether (PGM))

(Low refractive index layer-forming coating material A)
-Matrix component 100 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., X-12-2510, having a silicone skeleton with a solid content of 3%)
-Hollow silica particles 7 parts by mass (manufactured by Catalyst Kasei Kogyo Co., Ltd., ELCOM RK-1018SIV, hollow silica dispersion sol,
Solid content 20%, solvent is methyl isobutyl ketone (MIBK))
・ Solvent 42 parts by mass (Methyl isobutyl ketone (MIBK))

The following evaluation was performed about the obtained antireflection film. However, (9) For the evaluation of the waviness amplitude (545 nm) of the reflectance, a test was performed using a film sample in which only the hard coat layer was applied on the base film.
(1) Minimum reflectance Using a spectrophotometer [JASCO Corporation, U-best V-570], the reflectance at a wavelength of 380 to 780 nm is measured, and the minimum value is recorded. If the waveform is wavy, smoothing processing is performed to obtain the minimum value.
(2) Total light transmittance Measured using a haze computer [Suga Test Instruments Co., Ltd., HZ-1] according to JIS K 7361-1.
(3) Haze Measured according to JIS K 7136 using a haze computer [Suga Test Instruments Co., Ltd., HZ-1].
(4) Pencil hardness In accordance with JIS K 5400 8.4.2, a pencil [Mitsubishi Pencil Co., Ltd., Uni] is used to evaluate the scratch on the coating film.
(5) Steel wool resistance Steel wool [Nippon Steel Wool Co., Ltd., # 0000] is rolled and rubbed 10 times with a load of 200 g, and the state of the scratch is observed. judge.
○: No scratches at all.
Δ: 1 to 9 scratches are observed.
X: 10 or more scratches are observed.
(6) Surface resistivity It measured using the resistivity meter [Mitsubishi Chemical Corporation, Hirestar MCP-HT450].
(7) Curling property A sample is prepared in a size of 10 cm × 10 cm, and the curl heights at the four corners when the sample is placed on a horizontal surface are measured, and determined according to the following criteria.
○: Curl height is less than 20 mm Δ: Curl height is 20 mm or more and less than 50 mm ×: Curl height is 50 mm or more (8) Alkali resistance 1% NaOH aqueous solution is dropped on the film surface, left for 30 minutes, wiped off, and contaminated The situation is visually judged according to the following criteria.
Measured by.
○: No contamination is seen.
Δ: Slightly contaminated
X: Significantly contaminated.
(9) Waviness amplitude of reflectance (545 nm)
Using a UV-visible infrared spectrophotometer [JASCO Corporation, V-570], a reflection spectrum of a sample in the visible light region (a film sample obtained by coating only a hard coat layer on a base film) was obtained. . In the reflection spectrum, the waviness of the spectrum curve is amplified with the degree of iris. In the undulation of the reflection spectrum at a wavelength of 545 nm, the undulation amplitude (maximum value-minimum value) before and after the wavelength is obtained and determined according to the following criteria. In the three-wavelength fluorescent lamp (F10 light source), a specific wavelength is strong in the reflection spectrum, and three strong peaks are seen in the vicinity of 435 nm, 545 nm, and 610 nm. Regarding interference fringes, since the influence around the peak at 545 nm is particularly large, the waviness amplitude of the reflection spectrum at a wavelength of 545 nm is measured. As a more detailed measurement method of the waviness amplitude (545 nm) of the reflectance, as shown in FIG. 1, first, with the reflectance R% at 545 nm as a reference point, the nearest maximum value on the short wavelength side and the long wavelength side The most recent minimum value is determined, and the difference between the maximum value and the minimum value reflectivity R% is defined as the waviness amplitude (545 nm) of the reflectivity.
◎: Reflection wave amplitude is less than 0.40% ○: Reflectance wave amplitude is 0.40% or more and less than 0.6% Δ: Reflectance wave amplitude is 0.60% or more, 0 Less than 80% x: Waveform amplitude of reflectance is 0.80% or more (10) Interference fringes An antireflection film is placed on black paper, and a three-wavelength fluorescent lamp [Matsushita Electric Industrial Co., Ltd., Palook, 20W , Daylight white], the interference fringes around the fluorescent lamp image are observed, and the interference fringes are determined according to the following criteria.
A: No interference fringes are observed.
○: Interference fringes are hardly observed.
Δ: Interference fringes are faintly recognized.
X: Interference fringes are clearly recognized.

  The results are shown in Table 1 below.

Example 2
In Example 1, Example 1 was repeated except that a water-dispersible acrylic resin was applied in a thickness of 0.09 μm (refractive index of 1.58) as an easy-adhesive layer. The results are shown in Table 1 below.

Example 3
In Example 1, Example 1 was repeated except that the amount of antimony pentoxide sol used was changed to 133 parts by mass. The results are shown in Table 1 below.

Example 4
In Example 1, the amount of antimony pentoxide sol used was changed to 500 parts by mass, and the amount of polymer (macromonomer AA-6) having an unsaturated double bond copolymerizable at the terminal was changed to 30 parts by mass. Example 1 was repeated except that the changes were made. The results are shown in Table 1 below.

Example 5
In Example 1, Example 1 was repeated except that the thickness of the hard coat layer was changed to 4 μm. The results are shown in Table 1 below.

Example 6
In Example 1, Example 1 was repeated except that a water-dispersible polyester-based resin was applied at a thickness of 0.1 μm (refractive index of 1.57) as an easy-adhesive layer. The results are shown in Table 1 below.

Example 7
In Example 1, a water-dispersible polyester-based resin was applied as an easy-adhesive layer at a thickness of 0.1 μm (refractive index 1.57), and the thickness of the hard coat layer was changed to 1.5 μm, Example 1 was repeated. The results are shown in Table 1 below.

Example 8
In Example 1, Example 1 was repeated except that the polymer (macromonomer AA-6) having an unsaturated double bond copolymerizable at the terminal was not used. The results are shown in Table 1 below.

Examples 9-10
In Example 1, Example 1 was repeated except that the low refractive index layer-forming coating material was changed as follows. The results are shown in Table 2 below.

(Low refractive index layer-forming coating material B of Example 9)
· Hollow silica particles (particle size 40-60 nm) are added to ELCOM P-5012, silica matrix, fluorosilicone matrix, manufactured by Catalyst Kasei Kogyo Co., Ltd., solid content 2 mass%, main solvent isopropyl alcohol. The refractive index of the low refractive index layer formed by the paint is 1.40.

(Low Refractive Index Layer Coating Material C of Example 10)
-Shin-Etsu Chemical Co., Ltd. X-12-2510, solid content 3%, the refractive index of the low refractive index layer formed with this paint is 1.41.

Comparative Example 1
In Example 1, Example 1 was repeated except that a water-dispersible urethane-based resin was applied at a thickness of 0.1 μm (refractive index of 1.55) as an easy-adhesive layer. The results are shown in Table 3 below. Moreover, the waviness amplitude (545 nm) of the reflectance in Comparative Example 1 is shown in FIG.

Comparative Example 2
In Example 1, Example 1 was repeated except that the amount of antimony pentoxide sol used was changed to 33 parts by mass. The results are shown in Table 3 below.

Comparative Example 3
In Example 1, the usage amount of the antimony pentoxide sol was changed to 833 parts by mass, and the usage amount of the polymer (macromonomer AA-6) having an unsaturated double bond copolymerizable at the terminal was 30 parts by mass. Example 1 was repeated except that the changes were made. The results are shown in Table 3 below.

Comparative Example 4
In Example 1, Example 1 was repeated except that the thickness of the hard coat layer was changed to 0.2 μm. The results are shown in Table 3 below.

Comparative Example 5
In Example 1, Example 1 was repeated except that the thickness of the hard coat layer was changed to 6 μm. The results are shown in Table 3 below.

Examples 1 to 10, which are forms of the antireflection film of the present invention, have an effect of preventing interference fringes, have a low minimum reflectance, a high total light transmittance, a low haze, a high pencil hardness, and a steel resistance. It has good wool properties, low surface resistivity, excellent curling properties and alkali resistance, and has good properties as an antireflection film. In Example 3, since the amount of antimony pentoxide used was 40 parts by mass in terms of solid content with respect to 100 parts by mass of DPHA, the surface resistivity slightly increased, and the interference fringes were evaluated as ○. It was. In Example 4, the amount of antimony pentoxide used was a high blending ratio of 150 parts by mass in terms of solid content with respect to 100 parts by mass of DPHA, so the interference fringes were evaluated as o (however, transparency was hardly lowered). ). In Example 5, since the thickness of the hard coat layer was slightly thick at 4 μm, the interference fringes were evaluated as “good”. In Example 6, since the refractive index of the easy-adhesive layer was 1.57, which was slightly low, the interference fringes were evaluated as o. In Example 8, since a polymer having an unsaturated double bond copolymerizable at the terminal (macromonomer AA-6) was not used, the curl property was evaluated as Δ. In Example 10, since the hollow silica particles were not used for the low refractive index layer, the minimum reflectance was a slightly high value of 1.6%. The value of the waviness amplitude (545 nm) of the reflectance of the film obtained by applying only the hard coat layer on the base film of Examples 1 to 10 is 0.32 to 0.58%, which is evaluated as ◎ to ○. The evaluation of the interference fringes of the antireflection films of Examples 1 to 10 is also a result of the evaluation corresponding to the value of the waviness amplitude (545 nm) of the reflectance, as can be seen from the results in the table. .
On the other hand, in Comparative Example 1, the refractive index of the easy-adhesive layer is 1.55, which is outside the scope of the present invention. In Comparative Example 2, since the amount of antimony pentoxide added is too low and out of the range of the present invention, the interference fringes are evaluated as x, the surface resistivity is large, and the antistatic effect is not exhibited. In Comparative Example 3, since the amount of antimony pentoxide added is too high and out of the range of the present invention, the interference fringes are evaluated as x. In Comparative Example 4, the thickness of the hard coat layer is 0.2 μm, which is out of the range of the present invention, so that the pencil hardness is reduced to HB and the steel wool resistance is inferior. In Comparative Example 5, the thickness of the hard coat layer was 6 μm, which is outside the range of the present invention, and therefore the interference fringes were evaluated as x. The value of the waviness amplitude (545 nm) of the reflectance of the film in which only the hard coat layer is applied on the base film of Comparative Examples 1 to 5 is 0.81 to 2.40%, and all are x evaluations. The evaluations of the interference fringes of the antireflection films of Comparative Examples 1 to 5 are all x evaluations, which are the results corresponding to the values of the waviness amplitude (545 nm) of the reflectance described above.

  The antireflection film of the present invention has no noticeable interference fringes, low minimum reflectance, and excellent transparency, steel wool resistance, antistatic properties and curling properties. Therefore, the liquid crystal display device, plasma display panel, personal computer, It is useful for preventing reflection on the surface of a display such as a television or a touch panel.

It is a reflection spectrum curve of the film sample which apply | coated only the hard-coat layer on the base film of Example 1. FIG. In the wave of the reflection spectrum having a wavelength of 545 nm, a method for obtaining the wave amplitude (maximum value-minimum value) before and after the wavelength is shown. It is a reflection spectrum curve of the film sample which apply | coated only the hard-coat layer on the base film of the comparative example 1. In the wave of the reflection spectrum having a wavelength of 545 nm, a method for obtaining the wave amplitude (maximum value-minimum value) before and after the wavelength is shown.

Claims (9)

An antireflection film having a hard coat layer on a base film made of biaxially stretched polyethylene terephthalate, and further having a low refractive index layer on the hard coat layer,
The hard coat layer has a thickness of 0.5 to 5 μm;
The hard coat layer is blended with 100 parts by mass of ionizing radiation curable resin containing polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, and 20 to 200 parts by mass of antimony pentoxide, It is formed by curing this,
An antireflection film, wherein an easy-adhesive layer is provided between the base film and the hard coat layer, and a refractive index of the easy-adhesive layer is 1.56 to 1.62.   The antireflection film according to claim 1, wherein 5 to 20 parts by mass of a polymer having an unsaturated double bond copolymerizable at a terminal is further blended with 100 parts by mass of the ionizing radiation curable resin.   2. The antireflection film according to claim 1, wherein the polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule is dipentaerythritol hexaacrylate.   The antireflection film according to claim 1, wherein the antimony pentoxide has an average particle size of 5 to 100 nm.   The antireflection film according to claim 1, wherein the hard coat layer has a refractive index of 1.51 to 1.61.   The antireflective film according to claim 1, wherein the low refractive index layer contains 20 to 100 parts by mass of hollow silica particles in 100 parts by mass of a matrix component having a silicone skeleton.   The average particle diameter of the said hollow silica particle is 5-100 nm, The antireflection film of Claim 6 characterized by the above-mentioned. The surface resistivity is 1.0 × 10 ¹² Ω / sq. The antireflection film according to claim 1, wherein the antireflection film is as follows.   9. The antireflection film according to claim 1, wherein the total light transmittance is 90% or more.

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