JP5091043B2 - Antireflection film, optical component having the same, interchangeable lens, and imaging device - Google Patents

Description

  The present invention relates to an antireflection film in the visible range that is suitably used for an imaging device such as an interchangeable lens, an optical component having the same, an interchangeable lens, and an imaging device.

  High-performance single-focus lenses and zoom lenses widely used in photographic cameras, broadcast cameras, and the like have a lens barrel configuration of a large number of lens groups. Generally, these lenses are composed of about 10 to 40 lenses. Some lenses, such as wide-angle lenses, target images with a wide angle of view, and the incident angle of light increases at the periphery of such wide-angle lenses. The surface of these optical components such as lenses is combined with a dielectric film having a large or small refractive index different from the refractive index of the base material, and the thickness of each dielectric film is 1 / 2λ or Antireflection treatment is performed by a multilayer film using an interference effect such as 1 / 4λ.

  Further, the lens surface may be burned or scratched during the manufacturing process. In the burn phenomenon, when the optical glass is left in the atmosphere, a thin film is formed by elution of basic components in the glass due to condensation of water droplets on the glass surface or contact with water during the polishing process. There are a blue discoloration phenomenon and a white discoloration phenomenon in which components eluted from the glass cause some chemical reaction and precipitate as white spotted particles.

  Japanese Patent No. 3509804 (Patent Document 1) discloses an optical element in which a multilayer optical thin film made of an alkaline earth metal fluoride is formed on an optical substrate by at least one layer formed by a wet process. Yes. However, the refractive index is as high as about 1.39.

  In JP-A-2005-352303 (Patent Document 2) and JP-A-2006-3562 (Patent Document 3), an antireflection film comprising a plurality of layers is formed on a substrate, and the substrate and the refraction of each layer are formed. The refractive index decreases in order from the base material, the refractive index difference between each adjacent layer and the base material is 0.02 to 0.2, the physical layer thickness of each layer is 15 to 200 nm, and the outermost layer is a silica airgel layer A barrier film is disclosed. However, the silica airgel layer has low scratch resistance and durability.

  Japanese Patent Laid-Open No. 2006-130889 (Patent Document 4) has nanoscale micropores, a refractive index of 1.05 to 1.3, and a high transmittance of 90% or more from the visible light region to the near infrared region. A mesoporous silica thin film is disclosed. This mesoporous silica thin film is prepared by applying a mixture of a surfactant, a silica raw material such as tetraethoxysilane, water, an organic solvent, and an acid or alkali to a base material to prepare an organic-inorganic composite film. It is obtained by drying and photooxidation to remove organic components.

  Japanese Patent No. 3668126 (Patent Document 5) prepares a solution comprising a ceramic precursor such as tetraethoxysilane, a catalyst, a surfactant and a solvent as a method for forming a porous silica film having a low refractive index. Discloses a method of removing the solvent and surfactant.

  However, the mesoporous silica thin film of Patent Document 4 and the porous silica film of Patent Document 5 are hydrolyzed and polycondensed to form a silicate network around the micelles of the surfactant, and the network is thinned. Therefore, hydrolysis and polycondensation take a long time, resulting in a non-uniform film.

Japanese Patent Laid-Open No. 5-85778 (Patent Document 6) discloses that a plurality of dielectric films are laminated on the surface of a transparent optical component substrate to form an antireflection film, An optical system having an antireflection film in which the composition of the first layer close to is silicon oxide (SiO _x , x: 1 ≦ x ≦ 2) and the film thickness nd is 0.25λ ₀ ≦ nd (λ ₀ is the design wavelength) The parts are disclosed. According to such a configuration, even if burns or scratches are present on the surface of the optical component substrate, they can be made inconspicuous, but it is difficult to suppress the occurrence of burns.

Japanese Patent No. 3509804 JP 2005-352303 A JP 2006-3562 JP 2006-130889 Japanese Patent No. 3668126 JP-A-5-85778

  An object of the present invention is to have a uniform antireflection film having excellent transmittance characteristics in a high refractive index glass, generating less flare and ghost, etc., and having excellent scratch resistance and anti-scratch effect. An optical component, an interchangeable lens, and an imaging device are provided.

  As a result of diligent research in view of the above problems, the present inventors have achieved excellent antireflective properties in high-refractive index glass, anti-flare effect, anti-scratch effect, scratch resistance, durability by antireflective coating having the following constitution And the present invention has been conceived to achieve uniformity and uniformity of the antireflection film.

  That is, the antireflection film, optical component, interchangeable lens, and imaging device of the present invention have the following characteristics.

(1) An antireflection film obtained by laminating a first layer to a third layer on a base material in this order from the base material side, and in light having a wavelength region of 400 to 700 nm,
The base material has a refractive index of 1.60 to 1.93,
The first layer is a dense layer having an optical film thickness of 97.0 to 181.0 nm mainly composed of alumina,
The second layer is a dense layer having a refractive index of 1.33-1.50 and an optical film thickness of 124.0-168.5 nm;
The third layer is an aggregate of mesoporous silica nanoparticles, refractive index 1.07 to 1.18, Ri porous layer der an optical thickness of 112.5-169.5 nm,
The mesoporous silica nanoparticles have a hexagonal structure;
The pore diameter distribution of the third layer has two peaks, a peak due to intraparticle pores is in the range of 2 to 10 nm, and a peak due to interparticle pores is in the range of 5 to 200 nm. An antireflection film characterized by that.
( 2 ) The antireflection film as described in (1 ) above, wherein the volume ratio of the intraparticle pores to the interparticle pores is 1/15 to 1/1.
( 3 ) The antireflection film as described in (1) or (2 ) above, wherein the porosity of the third layer is 55 to 85%.
( 4 ) The antireflection film according to any one of (1) to ( 3 ), wherein the first layer has a refractive index of 1.60 to 1.72.
( 5 ) The antireflection film according to any one of (1) to ( 4 ), wherein the second layer is made of at least one material selected from the group consisting of MgF ₂ and SiO _2. Antireflection film.
( 6 ) In the antireflection film according to any one of the above (1) to ( 5 ), the reflectance in the wavelength region 450 to 600 nm of 0 ° incident light is 0.5% or less, and the wavelength region of 30 ° incident light An antireflection film characterized by having a reflectance at 400 to 650 nm of 1.0% or less.
( 7 ) In the antireflection film according to any one of (1) to ( 6 ), a fluororesin layer having a thickness of 0.4 to 100 nm and further having water repellency or water / oil repellency is provided on the third layer. An antireflection film comprising:
( 8 ) The antireflection film according to any one of (1) to ( 7 ), wherein the first layer or the second layer is formed by a vacuum deposition method.
( 9 ) The antireflection film according to any one of (1) to ( 8 ), wherein the third layer is formed by a sol-gel method.
( 10 ) In the antireflection film according to ( 9 ), the third layer is formed by aging a mixed solution of (i) a solvent, an acidic catalyst, an alkoxysilane, a cationic surfactant, and a nonionic surfactant. Nonionic surfactant having a cationic surfactant in the pores by hydrolyzing and polycondensing alkoxysilane, and (ii) adding a basic catalyst to the obtained acidic sol containing silicate And (iii) coating the sol on the second layer, (iv) drying to remove the solvent, and (v) firing to form a cationic interface. An antireflection film formed by removing an activator and a nonionic surfactant.
( 11 ) An optical component comprising the antireflection film according to any one of (1) to ( 10 ) above.
( 12 ) An interchangeable lens comprising the optical component according to ( 11 ) above.
( 13 ) An imaging apparatus comprising the optical component according to ( 11 ).

According to the present invention, in a high refractive index glass, an antireflection property excellent in a visible light wavelength region of 400 to 700 nm by a three-layer antireflection film, a flare and ghost prevention effect, an anti-burn effect, an abrasion resistance, Durability and uniformity of the antireflection film can be obtained.

  In addition, since the antireflection effect is extremely high as compared with the conventional antireflection film and the scratch resistance is excellent, the antireflection film can be used for flare and ghost countermeasures such as an interchangeable lens of an SLR camera used outdoors and for preventing burns.

[1] Base Material FIG. 1 shows a base material 3 on which the antireflection film 1 of the present invention is formed. The substrate 3 shown in FIG. 1 is a flat plate, but the present invention is not limited to this and may be a lens, a prism, a light guide, a film, or a diffraction element. The material of the substrate 3 may be any of glass, crystalline material, and plastic. Specific examples include optical glass such as BaSF2, SF5, LaF2, LaSF09, LaSF01, and LaSF016, Pyrex (registered trademark) glass, quartz, blue plate glass, white plate glass, and the like.

The refractive index of the base material 3 is 1.60 to 1.93 in the wavelength region 400 to 700 nm,
It is preferably 1.62 to 1.81. When the refractive index of the substrate 3 is in this range, the optical performance is improved in the visible light wavelength band, and the interchangeable lens can be made compact.

[2] anti-reflective coating
(1) Configuration of Antireflection Film The antireflection film 1 is formed on the surface of the substrate 3 and has a predetermined material or a predetermined refractive index and optical film thickness [refractive index (n) × physical film thickness (d)]. It consists of a first layer to a third layer. That is, the antireflection film 1 of the present invention has a first layer 11 that is a dense layer having an optical film thickness of 97.0 to 181.0 nm mainly composed of alumina, and a refractive index of 1.33 to 1.50. A second layer 12 which is a dense layer having an optical film thickness of 124.0 to 168.5 nm, and a third layer which is a porous layer having a refractive index of 1.07 to 1.18 and an optical film thickness of 112.5 to 169.5 nm, consisting of an assembly of mesoporous silica nanoparticles. And 13.

  The antireflection film 1 has a reflectance of 0.5% or less, more preferably 0.4% or less, in a wavelength region of 450 nm to 600 nm of 0 ° incident light. Further, the reflectance of 30 ° incident light in the wavelength region of 400 nm to 650 nm is 1.0% or less, and more preferably 0.5% or less.

(2) First layer The first layer 11 of the antireflection film 1 is a dense layer mainly composed of alumina. The first layer 11 is preferably made of only alumina (aluminum oxide). The purity of alumina is preferably 99% or more.

  The refractive index of the first layer (alumina layer) 11 containing alumina as a main component is preferably 1.60 to 1.72, and more preferably 1.62 to 1.67. The optical film thickness of the first layer 11 is preferably 98.5 to 158.0 nm. Alumina has advantages such as high adhesion, high permeability in a wide wavelength band, high hardness, excellent wear resistance, and good cost performance. In addition, since alumina has excellent shielding properties against water vapor, it is possible to prevent burns on the surface of the substrate by making the first layer a dense layer containing alumina as a main component.

(3) Second Layer The second layer 12 is a dense layer made of at least one material selected from the group consisting of MgF ₂ and SiO ₂ . The refractive index of the second layer 12 is preferably 1.37 to 1.43, and the optical film thickness is preferably 125.0 to 155.0 nm.

(4) Third layer The third layer 13 is an aggregate of mesoporous silica nanoparticles, has a low refractive index, and can exhibit an excellent antireflection function. The refractive index of the third layer (mesoporous silica porous layer) 13 is preferably 1.08 to 1.16, and the optical film thickness is preferably 115.0 to 155.0 nm. The pore diameter between particles of the porous layer is preferably 5 to 100 nm, and the porosity is preferably 55 to 85%, more preferably 58.5 to 83.5%.

  Mesoporous silica nanoparticles have a hexagonal structure compared to conventional silica airgel membranes, and mesopores are regularly and uniformly formed in the particles. Therefore, it has high strength and high porosity, and has a low refractive index and excellent scratch resistance. The mesoporous silica nanoparticles of the third layer 13 may have a cubic structure or a lamellar structure in addition to the hexagonal structure.

  An example of the hexagonal structure of mesoporous silica nanoparticles is shown in FIG. The mesoporous silica nanoparticles 200 are composed of a silica skeleton 200b having mesopores 200a, and have a porous structure in which the mesopores 200a are regularly arranged in a hexagonal shape. The average particle size of the mesoporous silica nanoparticles 200 is preferably 200 nm or less, and more preferably 20 to 50 nm. When the average particle diameter is more than 200 nm, it is difficult to adjust the film thickness of the mesoporous silica porous layer 13, and the antireflection characteristics and scratch resistance are low. The average particle diameter of the mesoporous silica nanoparticles 200 is determined by a dynamic light scattering method. The refractive index of the mesoporous silica porous layer 13 depends on the porosity, and the refractive index decreases as the porosity increases.

  The pore size distribution of the mesoporous silica porous layer 13 preferably has two peaks as shown in FIG. This pore size distribution is determined by the nitrogen adsorption method. Specifically, an isothermal desorption curve of nitrogen is obtained for the mesoporous silica porous layer 13, and this is analyzed by the BJH method. The horizontal axis is the pore diameter, and the vertical axis is the log differential pore volume. As the BJH method, for example, the method described in “Method for obtaining mesopore distribution” (EP Barrett, LG Joyner, and PP Halenda, J. Am. Chem. Soc., 73, 373 (1951)) is used. . The log differential pore volume is a change amount of the differential pore volume dV with respect to the logarithmic difference value d (logD) of the pore diameter D, and is expressed by dV / d (logD).

  The first peak on the small pore diameter side indicates the diameter of the intraparticle pores, and the second peak on the large pore diameter side indicates the diameter of the interparticle pores. The pore size distribution of the mesoporous silica porous layer 13 preferably has a peak due to the intraparticle pore diameter in the range of 2 to 10 nm and a peak due to the interparticle pore diameter in the range of 5 to 200 nm.

The ratio of pore volume within a particle V ₁ and inter-particle pore volume V ₂ is preferably 1/15 to 1/1. The mesoporous silica porous layer 13 having this ratio V ₁ / V ₂ in the above range has a small refractive index of 1.18 or less. The ratio V ₁ / V ₂ is more preferably 1/10 or more and less than 1 / 1.5.

The method for obtaining the ratio V ₁ / V ₂ is shown below. In the pore diameter distribution graph shown in FIG. 3, a point where the vertical axis coordinate is minimum between the first and second peaks is a point E, and a straight line passing through the point E and parallel to the horizontal axis is a base line L ₀ . In the pore size distribution, tangent lines (maximum inclination lines) having the maximum inclination in the vicinity of the first peak are L ₁ and L _2, and maximum inclination lines in the vicinity of the second peak are L ₃ and L ₄ . The intersection of the maximum slope line L ₁ ~L ₄ and the baseline L ₀ and each point to D, the horizontal axis coordinate of the intersection point to D and D _A to D _D. By the BJH method, the total volume V ₁ of the pores in the range from D _A to D _B and the total volume V ₂ of the pores in the range from D _C to D _D are calculated, and their ratio V ₁ / V ₂ Ask for.

  The film forming method of the mesoporous silica porous layer 13 is preferably a wet method such as a sol-gel method. The mesoporous silica porous layer 13 may be hydrophobized. The porous layer subjected to the hydrophobic treatment has excellent moisture resistance and durability.

(5) Fluororesin Layer The antireflection film of the present invention may have a fluororesin layer having water repellency or water / oil repellency as the outermost layer. The antireflection film 2 shown in FIG. 4 is provided with a first layer 21, a second layer 22, and a third layer 23 from the substrate 3 side, and further a fluororesin layer 24 is provided thereon.

  The material of the fluororesin layer 24 is not particularly limited as long as it is colorless and highly transparent, and examples thereof include organic compounds and organic-inorganic hybrid polymers containing fluorine.

  Examples of the fluorine-containing organic compound include a fluororesin and a fluorinated pitch [for example, CFn (n: 1.1 to 1.6)]. Examples of the fluororesin include a polymer of a fluorine-containing olefin compound, and a copolymer comprising a fluorine-containing olefin compound and a monomer copolymerizable therewith. Examples of such (co) polymers include polytetrafluoroethylene (PTFE), tetraethylene-hexafluoropropylene copolymer (PFEP), ethylene-tetrafluoroethylene copolymer (PETFE), tetrafluoroethylene-par. Fluoroalkyl vinyl ether copolymer (PFA), ethylene-chlorotrifluoroethylene copolymer (PECTFE), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (PEPE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF). A polymer obtained by polymerizing a commercially available fluorine-containing composition may be used as the fluororesin. Examples of commercially available fluorine-containing compositions include Opstar (manufactured by JSR Corporation) and Cytop (manufactured by Asahi Glass Co., Ltd.).

Examples of the organic-inorganic hybrid polymer containing fluorine include an organosilicon polymer having a fluorocarbon group. Examples of the organosilicon polymer having a fluorocarbon group include a polymer obtained by hydrolyzing a fluorine-containing silane compound having a fluorocarbon group. As the fluorine-containing silane compound, the following formula (1):
CF ₃ (CF ₂ ) _a (CH ₂ ) ₂ SiR _b X _c ... (1)
(However, R is an alkyl group, X is an alkoxy group or a halogen atom, a is an integer of 0-7, b is an integer of 0-2, c is an integer of 1-3, b + c = 3)). Specific examples of the compound represented by the formula (1) include CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CH ₂ ) ₂ SiCl ₃ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ SiCl ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH _{2) 2 SiCl 3, CF 3} (CF 2) 7 (CH 2) 2 SiCH 3 (OCH 3) 2, CF 3 (CF 2) 7 (CH 2) 2 SiCH 3 Cl 2 and the like. Examples of commercially available organosilicon polymers include Novec EGC-1720 (Sumitomo 3M), XC98-B2472 (GE Toshiba Silicone) and X71-130 (Shin-Etsu Chemical Co., Ltd.).

  The thickness of the fluororesin layer 24 is preferably 0.4 to 100 nm, and more preferably 10 to 80 nm. If the thickness of the fluororesin layer 24 is less than 0.4 nm, the water and oil repellency is insufficient, and if it exceeds 100 nm, the transparency and optical properties of the antireflection film are impaired. The refractive index of the fluororesin layer 24 is preferably 1.5 or less, and more preferably 1.45 or less. The film formation method of the fluororesin layer 24 may be a vacuum deposition method, but a wet method such as a sol-gel method is preferable.

[3] Method for forming antireflection film
(1) Formation method of the first layer and the second layer The first layer 11 and the second layer 12 of the antireflection film are preferably formed by a physical film formation method. Examples of the physical film forming method include a vacuum vapor deposition method and a sputtering method, but the vacuum vapor deposition method is particularly preferable in view of manufacturing cost and processing accuracy. Examples of the vacuum deposition method include a resistance overheating method and an electron beam method.

  An electron beam vacuum deposition method will be described below. The vacuum deposition apparatus 30 shown in FIG. 7 is provided with a rotatable rotating rack 32 for placing a plurality of base materials 3 on the inner surface and a crucible 36 for placing a deposition material in a vacuum chamber 31. A vapor deposition source 33, an electron beam irradiator 38, a heater 39, and a vacuum pump connection port 35 connected to the vacuum pump 40 are provided. In order to form the first layer 11 and the second layer 12 of the antireflection film on the base material 3, first, the base material 3 is placed on the rotating rack 32 so that the surface faces the vapor deposition source 33, and the vapor deposition material 37 is attached. Place on crucible 36. Subsequently, after the inside of the vacuum chamber 31 is depressurized by the vacuum pump 40 connected to the vacuum pump connection port 35, the base material 3 is heated by the heater 39, and the rotating rack 32 is rotated by the rotating shaft 34, while the vapor deposition material The evaporation material 37 is heated by irradiating an electron beam from the electron beam irradiator 38 toward the substrate 37. The vapor deposition material 37 evaporated by heating is vapor deposited on the surface of the base material 3, and each layer of the antireflection film is formed on the surface of the base material 3.

The initial degree of vacuum in the vacuum deposition method is preferably 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻⁶ Torr. When the degree of vacuum is less than 1.0 × 10 ⁻⁵ Torr, productivity is poor and vapor deposition is insufficient. When the degree of vacuum exceeds 1.0 × 10 ⁻⁶ Torr, the film forming accuracy is low. Moreover, it is preferable to heat the base material 3 during vapor deposition in order to improve the film forming accuracy. The substrate temperature during vapor deposition can be appropriately determined according to the heat resistance of the substrate 3 and the vapor deposition rate, but is preferably 60 to 250 ° C.

(2) Formation of third layer The third layer (mesoporous silica porous layer) 13 is aged from (i) a mixed solution of solvent, acidic catalyst, alkoxysilane, cationic surfactant and nonionic surfactant. By hydrolyzing and polycondensing alkoxysilane, and (ii) adding a basic catalyst to the acidic sol containing the resulting silicate, thereby having a cationic surfactant in the pores and a nonionic surfactant A sol containing mesoporous silica nanoparticles coated with an agent (referred to as “surfactant-mesoporous silica nanocomposite particles”), (iii) coating the sol on the second layer 12, and (iv) drying And (v) calcination to remove the cationic surfactant and the nonionic surfactant.

(a) Raw material
(a-1) Alkoxysilane The alkoxysilane may be a monomer or an oligomer. The alkoxysilane monomer preferably has 3 or more alkoxyl groups. By using an alkoxysilane having three or more alkoxyl groups as a starting material, a mesoporous silica porous layer having excellent uniformity can be obtained. Specific examples of the alkoxysilane monomer include methyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrapropoxysilane, diethoxydimethoxysilane, dimethyldimethoxysilane, dimethyldi An ethoxysilane is mentioned. The alkoxysilane oligomer is preferably a polycondensate of the above monomers. The alkoxysilane oligomer is obtained by hydrolysis and polycondensation of an alkoxysilane monomer. Specific examples of the alkoxysilane oligomer include silsesquioxane represented by the general formula RSiO _1.5 (R represents an organic functional group).

(a-2) Surfactant
(i) Cationic surfactant Specific examples of the cationic surfactant include alkyltrimethylammonium halide, alkyltriethylammonium halide, dialkyldimethylammonium halide, alkylmethylammonium halide, and alkoxytrimethylammonium halide. . Examples of the halogenated alkyltrimethylammonium include lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, stearyltrimethylammonium chloride, benzyltrimethylammonium chloride, and behenyltrimethylammonium chloride. Examples of the halogenated alkyltrimethylammonium include n-hexadecyltrimethylammonium chloride. Examples of the dialkyldimethylammonium halide include distearyldimethylammonium chloride and stearyldimethylbenzylammonium chloride. Examples of the halogenated alkylmethylammonium include dodecylmethylammonium chloride, cetylmethylammonium chloride, stearylmethylammonium chloride, and benzylmethylammonium chloride. Examples of the halogenated alkoxytrimethylammonium include octadecyloxypropyltrimethylammonium chloride.

(ii) Nonionic surfactant Examples of the nonionic surfactant include block copolymers of ethylene oxide and propylene oxide, and polyoxyethylene alkyl ethers. As a block copolymer of ethylene oxide and propylene oxide, for example, the formula: RO (C ₂ H ₄ O) _a- (C ₃ H ₆ O) _b- (C ₂ H ₄ O) _c R (where a and c are each 10 to 120, b represents 30 to 80, and R represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms). Examples of commercially available block copolymers include Pluronic (registered trademark, BASF). Examples of the polyoxyethylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether.

(a-3) Catalyst
(i) Acidic catalyst Examples of the acidic catalyst include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as formic acid and acetic acid.

(ii) Basic catalyst Examples of the basic catalyst include ammonia, amine, NaOH, and KOH. Preferred examples of amines include alcohol amines and alkyl amines (eg methylamine, dimethylamine, trimethylamine, n-butylamine, n-propylamine).

(a-4) Solvent Pure water is preferably used as the solvent.

(b) Formation method
(b-1) Hydrolysis and polycondensation under acidic conditions An acidic solution is prepared by adding an acidic catalyst to a solvent, and an acidic mixed solution is prepared by adding a cationic surfactant and a nonionic surfactant to the acidic solution. To prepare. Alkoxysilane is added to this acidic mixed solution, followed by hydrolysis and polycondensation. At this time, the pH of the acidic mixed solution is preferably about 2. Thereby, since the pH of the isoelectric point of the silanol group of alkoxysilane is about 2, the silanol group can exist stably in the acidic mixed solution. The solvent / alkoxysilane molar ratio is preferably 30-300. When this molar ratio is less than 30, the degree of polymerization of alkoxysilane is too high, and when it exceeds 300, the degree of polymerization of alkoxysilane is too low.

The molar ratio of the cationic surfactant / solvent is preferably 1 × 10 ^{−4 to} 3 × 10 ⁻³ , and more preferably 1.5 × 10 ⁻⁴ to 2 × 10 ⁻³ . Thereby, mesoporous silica nanoparticles having excellent mesopore regularity can be obtained.

The molar ratio of cationic surfactant / alkoxysilane is preferably 1 × 10 ^{−1 to} 3 × 10 ⁻¹ . When this molar ratio is less than 1 × 10 ⁻¹ , the mesoporous silica nanoparticle mesostructure (hexagonal array structure) is not sufficiently formed. If it exceeds 3 × 10 ⁻¹ , the particle size of the mesoporous silica nanoparticles becomes too large. This molar ratio is more preferably 1.5 × 10 ^{−1 to} 2.5 × 10 ⁻¹ .

The nonionic surfactant / alkoxysilane molar ratio is preferably 5.0 × 10 ^{−3 to} 5.0 × 10 ⁻² . When this molar ratio is less than 5.0 × 10 ⁻³ , the refractive index of the porous mesoporous silica layer exceeds 1.18.

  The molar ratio of the cationic surfactant / nonionic surfactant is preferably 4 to 30, and more preferably 5 to 25. Thereby, mesoporous silica nanoparticles having excellent mesopore regularity can be obtained.

  The solution containing alkoxysilane is aged by vigorously stirring at 20-25 ° C. for 1-24 hours. Hydrolysis and polycondensation proceed by aging, and an acidic sol containing a silicate oligomer is generated.

(b-2) Hydrolysis and polycondensation under basic conditions A basic catalyst is added to the obtained acidic sol to make it basic, and further hydrolysis and polycondensation are performed. The pH of the basic sol is preferably 9-12. By adding a basic catalyst, a silicate skeleton is formed around the cationic surfactant micelle, and a regular hexagonal array grows to form particles in which silica and the cationic surfactant are combined. . As the composite particles grow, the effective charge on the surface decreases, so that the nonionic surfactant is adsorbed on the surface. As a result, a surfactant-mesoporous silica nanocomposite particle (see FIG. 2 for the particle shape) having a cationic surfactant in the pores and having a surface coated with a nonionic surfactant is included. Sol can be obtained [for example, Hiroaki Imai, “Chemical Industry”, Chemical Industry, September 2005, Vol. 56, No. 9, pp.688-693].

  In the process of forming the surfactant-mesoporous silica nanocomposite particles, the nonionic surfactant is adsorbed on the surface, so that the growth of the composite particles is suppressed. Therefore, by using two types of surfactants, cationic and nonionic, the average particle size of the obtained surfactant-mesoporous silica nanocomposite particles is 200 nm or less, and mesopores have excellent regularity. .

(b-3) Coating The sol containing the surfactant-mesoporous silica nanocomposite particles is coated on the surface of the second layer. Examples of the coating method include a spin coating method, a dip coating method, a spray coating method, a flow coating method, a bar coating method, a reverse coating method, a flexo method, a gravure coating method, a printing method, and a method using these in combination. The thickness of the obtained porous layer can be adjusted by the rotation speed of the substrate in the spin coating method, the pulling speed in the dipping method, the concentration of the coating solution, and the like. The rotation speed of the substrate in the spin coating method is preferably 500 to 10,000 rpm.

  A basic aqueous solution having the same pH as that of the sol may be added as a dispersion medium before coating so that the concentration and fluidity of the sol containing the surfactant-mesoporous silica nanocomposite particles are in an appropriate range. The ratio of the surfactant-mesoporous silica nanocomposite particles in the coating solution is preferably 10 to 50% by mass. Thereby, a uniform porous layer is obtained.

(b-4) Drying The applied sol is dried to evaporate the solvent. The drying conditions are not particularly limited, and can be appropriately determined according to the heat resistance of the base material 3, the first layer, and the second layer. Drying may be natural drying or heat treatment at 50 to 200 ° C. for 15 minutes to 1 hour.

(b-5) Firing The mesoporous silica porous layer 13 is formed by firing the dried film to remove the cationic surfactant and the nonionic surfactant. The firing temperature is preferably 300 ° C to 500 ° C. If the firing temperature is less than 300 ° C., firing is insufficient, and if the firing temperature exceeds 500 ° C., the refractive index of the antireflection film 1 exceeds 1.18. The firing temperature is more preferably 350 ° C to 450 ° C. The firing time is preferably 1 to 6 hours, and more preferably 2 to 4 hours.

[4] Optical component having antireflection film The antireflection film of the present invention is excellent in antireflection properties and scratch resistance, and the optical component having the antireflection film of the present invention is an interchangeable lens for a single lens reflex camera or a single lens reflex camera. It is useful for imaging devices such as video cameras.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
The antireflection film 1 of Example 1 was formed according to the layer structure shown in Table 1. The refractive index of each layer is the refractive index for light having a wavelength of 550 nm. The formation procedure of each layer is shown below.

[1] Formation of first layer and second layer
On the surface of the optical lens made of LaSF01, antireflection films of the first layer and the second layer made of dense layers having the constitution shown in Table 1 were formed by an electron beam vacuum deposition method using the apparatus shown in FIG. Here, the conditions for vapor deposition were an initial vacuum of 1.2 × 10 ⁻⁵ Torr and a substrate temperature of 230 ° C.

[2] Formation of third layer
To pH 2 hydrochloric acid (0.01N) 40 g, n-hexadecyltrimethylammonium chloride (manufactured by Kanto Chemical Co., Inc.) 1.21 g (0.088 mol / L), and block copolymer HO (C ₂ H ₄ O) _106- (C ₃ 7.56 g (0.014 mol / L) of H ₆ O) _70- (C ₂ H ₄ O) ₁₀₆ H (trade name “Pluronic F127”, Sigma-Aldrich) was added, and the mixture was stirred at 23 ° C. for 1 hour. Add Silane (Kanto Chemical Co., Ltd.) 4.00 g (0.45 mol / L), stir at 23 ° C for 3 hours, then add 3.94 g (1.51 mol / L) 28 mass% aqueous ammonia to adjust the pH to 11. And stirred at 23 ° C. for 0.5 hour. The obtained surfactant-mesoporous silica nanocomposite solution was applied to the surface of the second layer by spin coating, dried at 80 ° C. for 0.5 hours, and then fired at 400 ° C. for 3 hours.

The medium in contact with the outermost layer was air, and the characteristics of the obtained antireflection film were measured. A lens reflectometer (model number: USPM-RU, manufactured by Olympus Corporation) was used to measure the refractive index and physical film thickness. The ratio V ₁ / V ₂ of the third layer was 1 / 2.1.

Example 2
An antireflection film of Example 2 was formed according to the layer constitution of Table 2 in the same manner as in Example 1 except that 4.32 g (0.008 mol / L) of the block copolymer “Pluronic F127” was added. The medium in contact with the outermost layer was air, and the characteristics of the obtained antireflection film were measured in the same manner as in Example 1. The ratio V ₁ / V ₂ of the third layer was 1 / 1.9. Further, the outermost surface of the obtained antireflection film had excellent scratch resistance.

  FIG. 5 and FIG. 6 show the spectral characteristics of reflectance when light in the wavelength region of 350 nm to 850 nm is applied to the optical lens having the antireflection film obtained in Examples 1 and 2 at incident angles of 0 ° and 30 °. Shown in

  As shown in FIGS. 5 and 6 in the first and second embodiments, the reflectivity is 0.5% or less in the visible light region of 450 nm to 600 nm in the wavelength region of 0 ° incident light, and the wavelength region of 30 ° incident light. It was found that the reflectance at 400 nm to 650 nm is 1.0% or less, and has excellent reflectance characteristics.

  Further, flare and ghost were not generated in the images taken using the optical lenses obtained in Examples 1 and 2.

It is sectional drawing which shows the anti-reflective film by one Example of this invention formed in the surface of a base material. It is a perspective view which shows an example of the mesoporous silica particle which comprises the 3rd layer of the antireflection film of FIG. It is a graph which shows the hole diameter distribution of the 3rd layer of the antireflection film of FIG. It is sectional drawing which shows the anti-reflective film by another Example of this invention formed in the surface of a base material. 3 is a graph showing the spectral reflectance of the antireflection film of Example 1. 6 is a graph showing the spectral reflectance of the antireflection film of Example 2. It is a block diagram which shows an example of the apparatus which forms an antireflection film.

Explanation of symbols

1, 2 ... Antireflection film 3 ... Base material

Claims (13)

An antireflection film formed by laminating a first layer to a third layer in this order from the base material side on a base material, and in light having a wavelength region of 400 to 700 nm,
The base material has a refractive index of 1.60 to 1.93,
The first layer is a dense layer having an optical film thickness of 97.0 to 181.0 nm mainly composed of alumina,
The second layer is a dense layer having a refractive index of 1.33-1.50 and an optical film thickness of 124.0-168.5 nm;
The third layer is an aggregate of mesoporous silica nanoparticles, refractive index 1.07 to 1.18, Ri porous layer der an optical thickness of 112.5-169.5 nm,
The mesoporous silica nanoparticles have a hexagonal structure;
The pore diameter distribution of the third layer has two peaks, a peak due to intraparticle pores is in the range of 2 to 10 nm, and a peak due to interparticle pores is in the range of 5 to 200 nm. An antireflection film characterized by that. The antireflection film according to claim 1 , wherein a volume ratio of the intra-particle pores to the inter-particle pores is 1/15 to 1/1. The antireflection film according to claim 1 or 2 , wherein the porosity of the third layer is 55 to 85%. The anti-reflection film according to any one of claims 1 to 3 antireflection film refractive index of the first layer is characterized by a 1.60 to 1.72. The anti-reflection film according to any one of claims 1 to 4, wherein the second layer antireflection film, which comprises at least one material selected from the group consisting of MgF ₂ and SiO _2. The anti-reflection coating according to any one of claims. 1 to 5, 0 ° reflectance in the wavelength region 450 to 600 nm of the incident light is 0.5% or less, reflection in the wavelength range 400 to 650 nm of 30 ° incident light An antireflection film having a rate of 1.0% or less. The anti-reflection film according to any one of claims 1 to 6, characterized by having a fluororesin layer having a thickness of 0.4-100 nm with further water repellency or water- and oil-repellency on the third layer Antireflection film. The anti-reflection film according to any one of claims 1 to 7, wherein the first layer or the second layer antireflection film, which is formed by a vacuum deposition method. The antireflection film according to any one of claims 1 to 8 , wherein the third layer is formed by a sol-gel method. 10. The antireflection film according to claim 9 , wherein the third layer comprises (i) aging a mixed solution of a solvent, an acidic catalyst, an alkoxysilane, a cationic surfactant and a nonionic surfactant to hydrolyze the alkoxysilane. (Ii) By adding a basic catalyst to the resulting acidic sol containing silicate, it has a cationic surfactant in the pores, and the surface is coated with a nonionic surfactant And (iii) coating the sol on the second layer, (iv) drying to remove the solvent, and (v) calcining to obtain the cationic surfactant and the non-solubilized mesoporous silica nanoparticles. An antireflection film formed by removing an ionic surfactant. Optics, characterized in that it has an antireflection film of any of claims 1-10. 12. An interchangeable lens comprising the optical component according to claim 11 . 12. An imaging device comprising the optical component according to claim 11 .

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