JP2019185050A - Optical member and production method of optical member - Google Patents

Abstract

To provide an optical member having excellent optical characteristics and excellent wear resistance.SOLUTION: An optical member comprises base material and an anti-reflection film disposed on the base material. The anti-reflection film has a porous layer on a surface opposed to the base material. The porous layer includes a plurality of silicon oxide particles, and a gap existing between the plurality of silicon oxide particles. The porous layer has alkyl-silyl groups represented by the following general formula (2) and/or the following formula (3) on a surface facing the gap of the silicon oxide particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical member excellent in optical characteristics and wear resistance, and a method for producing the optical member.

  Conventionally, in order to suppress reflection at the light incident / exit interface of an optical element, it is known to form an antireflection film in which optical films having different refractive indexes are laminated with a thickness of several tens to several hundreds of nanometers. It has been. In order to form these antireflection films, vacuum film formation methods such as vapor deposition and sputtering, and wet film formation methods such as dip coating and spin coating are used.

  The material used for the outermost layer of the antireflection film has a low refractive index and is a transparent material, such as inorganic materials such as silica, magnesium fluoride, and calcium fluoride, and organic materials such as silicone resin and amorphous fluororesin It is known to use.

  In recent years, it has been known that a low refractive film using a refractive index of air of 1.0 is used as an antireflection film in order to further reduce the reflectance. It is possible to lower the refractive index by forming voids in the silica or magnesium fluoride layer. For example, the refractive index can be lowered to 1.27 by providing a 30 volume% void in a magnesium fluoride thin film having a refractive index of 1.38. However, the low refractive index layer in which voids are formed has a problem that wear resistance is lowered.

  Patent Document 1 discloses an antireflection film in which an overcoat layer containing a fluoropolymer is provided on a low refractive index layer in order to improve wear resistance.

  Patent Document 2 discloses an antireflection film in which voids between hollow fine particles of a low refractive index layer in which hollow particles are bonded with a first binder are filled with a second binder in order to improve wear resistance. .

JP 2000-284102 A JP 2004-258267 A

  However, in the cited document 1, there is a problem that the coating liquid for forming the overcoat layer penetrates into the voids in the low refractive index layer and the refractive index of the low refractive index layer is increased.

  Further, in Cited Document 2, since the second binder is filled in the gaps between the hollow fine particles, there is a problem that the refractive index is higher than that of the antireflection film not filled with the second binder.

  The present invention has been made in view of such background art, and provides an optical member having an antireflection film having wear resistance and a low refractive index, and a method for producing the optical member.

The optical member according to the present invention is an optical member having a base material and an antireflection film provided on the base material, and the antireflection film is porous on the surface opposite to the base material. The porous layer includes a plurality of silicon oxide particles and voids existing between the plurality of silicon oxide particles, and the surface of the silicon oxide particles facing the voids, It has an alkylsilyl group represented by the following general formula (2) and / or the following formula (3).

(In the formula, R2 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)

(In the formula, R3 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)

  Further, the method for producing an optical member according to the present invention includes a forming step of forming a porous layer having voids between a plurality of silicon oxide particles on a substrate, and an atmosphere containing a silazane compound. And a surface treatment step of alkylsilylating the surface of the silicon oxide particles facing the voids.

  According to the present invention, an optical member having excellent optical properties and wear resistance can be provided.

It is the schematic which shows one embodiment of the optical member of this invention. It is the schematic which shows one embodiment of the optical member of this invention. It is the schematic which shows one embodiment of the manufacturing method of the optical member of this invention. It is the schematic which shows one embodiment of the manufacturing method of the optical member of this invention. It is the schematic which shows one embodiment of the manufacturing method of the optical member of this invention.

  Hereinafter, the present invention will be described in detail.

[Optical member]
FIG. 1 is a schematic view showing an embodiment of the optical member of the present invention.

  The optical member 1 of the present invention has at least a base material 2 and an antireflection film 4 having a porous layer 3 on the base material 2. The porous layer 3 has silicon oxide particles 5 and a binder 6.

  As shown in FIG. 1, in the porous layer 3, silicon oxide particles 5 are bonded with a binder 6. The surfaces of the silicon oxide particles 5 and the binder 6 are alkylsilylated and have alkylsilyl groups. That is, the interface 5 'between the silicon oxide particles 5 and the atmosphere and the interface 6' between the binder 6 and the atmosphere are alkylsilylated.

  In the porous layer 3, the silicon oxide particles 5 may be in contact with each other or may be bonded with a binder interposed between the silicon oxide particles 5. From the viewpoint of improving the wear resistance, it is preferable that the silicon oxide particles 5 are in contact with each other in the porous layer 3.

  FIG. 2 is a schematic view showing another embodiment of the optical member 1 of the present invention. In FIG. 2, an oxide layer 7 is provided between the substrate 2 and the porous layer 3. The oxide layer 7 is preferably a laminate of a high refractive index layer and a low refractive index layer. As the high refractive index layer, a layer containing zirconium oxide, titanium oxide, tantalum oxide, niobium oxide, or hafnium oxide can be used. As the low refractive index layer, a layer containing silicon oxide or magnesium fluoride can be used.

  The optical member of the present invention can be used for optical lenses, optical mirrors, filters, and optical films. Among these, it is preferable to use for an optical lens.

(Base material)
The substrate 2 can use glass, resin, or the like. Moreover, the shape is not limited, A plane, a curved surface, a concave surface, a convex surface, and a film form may be sufficient.

(Silicon oxide particles)
The silicon oxide particles 5 preferably have an average particle size of 10 nm or more and 80 nm or less, and more preferably 12 nm or more and 60 nm or less. When the average particle diameter of the silicon oxide particles 5 is less than 10 nm, it is difficult to lower the refractive index because both voids between the particles and within the particles become too small. Moreover, when the average particle diameter exceeds 80 nm, the size of the voids between the particles increases, so that large voids are likely to be generated, and scattering associated with the size of the particles is not preferable.

  Here, the average particle diameter of the silicon oxide particles is the average ferret diameter. This average ferret diameter can be measured by image processing as observed with a transmission electron microscope image. As the image processing method, commercially available image processing such as image Pro PLUS (manufactured by Media Cybernetics) can be used. In a predetermined image area, if necessary, the contrast is adjusted appropriately, the average ferret diameter of each particle is measured by particle measurement, and the average value can be calculated and obtained.

  The silicon oxide particles 5 may have any of a perfect circle shape, an elliptical shape, a disk shape, a rod shape, a needle shape, a chain shape, and a square shape, and may be hollow particles having pores inside the particles. .

  Furthermore, since the porosity of the porous layer 3 can be increased to lower the refractive index, the silicon oxide particles 5 are preferably 50% by mass, more preferably 80% by mass, of hollow particles or chain-like particles. preferable.

  The hollow particles of silicon oxide are particles having pores inside and having a silicon oxide shell covering the outside of the pores. The air contained in the pores (refractive index 1.0) can lower the refractive index of the film compared to particles that do not have pores. The pores may be either single holes or porous and can be appropriately selected. The thickness of the shell of the hollow particles is preferably 10% to 50%, more preferably 20% to 35% of the average particle diameter. If the shell thickness is less than 10%, the strength of the particles is insufficient, which is not preferable. On the other hand, if the thickness of the shell exceeds 50%, the refractive index will not decrease significantly, which is not preferable.

  On the other hand, chain particles are particles in which a plurality of fine particles are linked in a chain or bead shape. Even if it becomes a film | membrane, since the chain | strand-like or beaded chain | strand form is maintained, the porosity can be raised compared with the time of using a single particle. In addition, since each particle can be made small, voids are unlikely to occur. The number of fine particles connected in one chain fine particle is 2 or more and 10 or less, preferably 3 or more and 6 or less. When the number of continuous fine particles exceeds 10, voids are likely to be generated, and the wear resistance is lowered.

  The silicon oxide particles 5 are fine particles mainly composed of SiO 2, and Si is preferably 80 atomic% or more, more preferably 90 atomic% or more among elements excluding oxygen. When Si is less than 80 atom%, the wear resistance is lowered because silanol (Si—OH) groups on the surface of fine particles that react with the binder 6 are reduced.

  In addition to SiO2, the silicon oxide particles 5 include metal oxides such as Al2O3, TiO2, ZnO2, and ZrO2, and organic components such as alkyl groups and fluorinated alkyl groups via silicon atoms in the silicon oxide particles or particles. Can be introduced on the surface.

  50 mass% or more and 90 mass% are preferable with respect to the porous layer 3, and, as for content of the silicon oxide particle 5, 65 mass% or more and 85 mass% are more preferable.

  The surface of the silicon oxide particles 5 is alkylacylated in the same manner as the binder 6 shown below.

(binder)
The binder 6 can be appropriately selected depending on the wear resistance, adhesion, and environmental reliability of the film, but has high affinity with the silicon oxide particles 5 and improves the wear resistance of the porous film 3. It is preferable to use a silicon oxide binder. Among the silicon oxide binders, it is preferable to use a silicate hydrolysis condensate.

  The weight average molecular weight of the silicon oxide binder is preferably 500 or more and 3000 or less in terms of polystyrene. If the weight average molecular weight is less than 500, cracks after curing are likely to occur, and the stability as a coating is lowered. On the other hand, if the weight average molecular weight exceeds 3000, the viscosity increases, and voids inside the binder tend to be non-uniform, so that large voids are likely to be generated.

  5 mass% or more and 40 mass% or less are preferable with respect to the porous layer 3, and, as for content of the binder 6, 10 mass% or more and 30 mass% or less are more preferable.

  The silicon oxide binder preferably has a composition represented by the following general formula (1).

(In Formula (1), R1 is an alkyl group having 1 to 8 carbon atoms, an alkenyl group, an alkynyl group, an aromatic ring, and an amino group, an isocyanate group, a mercapto group, an acryloyl group, or a halogen atom is substituted. Well, 0.90 ≦ m ≦ 0.99 is satisfied.)

  In the general formula (1), when m is less than 0.9, the hydrophilicity of the binder 6 is lowered, the interaction between the binder 6 and the silicon oxide particles 5 is weakened, and the wear resistance of the porous layer 3 is lowered. . It is more preferable that the general formula (1) satisfies 0.95 ≦ m ≦ 0.99.

  The surface of the binder 6 is alkylsilylated. When a silicon oxide binder is used, it is preferable that the binder has a silanol group. When the binder 6 has a silanol group inside, the abrasion resistance of the porous layer 3 is improved by hydrogen bonding.

  The alkylsilyl group introduced by alkylsilylation is a substituent represented by —SiR 3, ═SiR 2 or ≡SiR, and each R is a monovalent organic group. The smaller the bulk of the organic group, the smaller the steric hindrance between the organic groups, and the smaller the in-plane variation in water repellency and refractive index. The alkylsilyl group represented by the following formula (2) is alkylsilylated. Preferably it is. Moreover, it is preferable that it is alkylsilylated with the alkylsilyl group of following formula (3) at the point which can connect and replace two silanol groups and can obtain high water repellency.

(In the formula, R2 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)

(In the formula, R3 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)

  Two or more alkylsilyl groups can be used in combination.

(Porous layer)
The porous layer 3 preferably has a thickness of 80 nm to 200 nm, more preferably 100 nm to 160 nm. When the film thickness is less than 80 nm, it is difficult to obtain wear resistance, and when it exceeds 200 nm, scattering tends to increase.

  The porosity of the porous layer 3 is preferably 30% or more and 50% or less. If the porosity is less than 30%, the refractive index is high and a high antireflection effect may not be obtained. If the porosity exceeds 50%, the voids between the particles become too large and wear resistance becomes low.

  The refractive index of the porous layer 3 is preferably 1.19 or more and 1.30 or less, more preferably 1.22 or more and 1.27 or less, and 1.22 or more and 1.25 or less. Is more preferable.

  By subjecting the porous layer 3 to alkylsilylation, the contact angle between the surface of the porous layer 3 and water can be made 110 ° to 140 °. If the contact angle is less than 110 °, there are many silanol groups left without being alkylsilylated at the interface 5 ′, and therefore fine scratches may occur when wiping with a nonwoven fabric. On the other hand, when the contact angle exceeds 140 °, there is a possibility that a residue other than the alkylsilyl group at the interface 5 ′ (such as the raw material used for alkylsilylation) may remain, and the refractive index is locally high. In some cases, uniform optical characteristics cannot be obtained.

  In the porous layer 3, among the silanol groups present on the surface of the silicon oxide particles 5 and the silanol groups in the silicon oxide binder 6, the hydrogen of the silanol groups remaining at the interface with air is substituted with alkylsilyl groups. . If the silanol groups in these portions remain without being alkylsilylated, the porous layer 3 has a high affinity with a solvent such as alcohol or non-woven fiber, so that the surface of the porous layer 3 becomes alcohol. Marks remain when touched, and scratches remain when rubbed with a non-woven fabric. Moreover, the porous layer 3 which is not alkylsilylated is easily contaminated by a silicone component volatilized from a caulking material used for an inner wall of an apparatus or the like. On the other hand, since the porous layer 3 of the present invention is alkylsilylated, it is hardly contaminated with a silicone component or the like.

  The porous layer 3 has many voids because the surfaces of the silicon oxide particles 5 and the binder 6 are alkylsilylated, and has a low refractive index and a high water repellency. In the porous layer 3, since the silicon oxide particles 2 and the binder 6 form a strong Si—O—Si bond, the water repellency is hardly lowered even by external stimuli such as heat and wiping.

[Method for producing optical member]
In the method for producing the optical member 1 of the present invention, the porous layer 3 in which the silicon oxide particles 5 are bonded with the binder 6 is formed on the substrate 2 or on the surface of one or more layers formed on the substrate 2. A forming step.

  For the step of forming the porous layer 3, either a dry method or a wet method may be used, but it is preferable to use a wet method that can easily form the porous layer 3.

  As the step of forming the porous layer 3 by a wet method, a method of applying a dispersion containing both the silicon oxide particles 5 and the binder 6 and a method of applying the silicon oxide particle dispersion and the binder solution in this order are used. it can. Since the abrasion resistance of the porous layer 3 can be improved, it is preferable to use a method in which a dispersion of silicon oxide particles 5 and a binder 6 solution are applied in order.

  A method of coating the dispersion of silicon oxide particles 5 and the binder 6 solution in order will be described with reference to the drawings. A dispersion of silicon oxide particles 5 is applied on the substrate 2 to form a layer in which the silicon oxide particles 5 are stacked as shown in FIG. At this time, it is considered that the silicon oxide particles 5 in contact with each other form a loosely bonded state in which the silanol groups on the particle surfaces are hydrogen bonds. Subsequently, the binder 6 solution is applied to the layer in which the silicon oxide particles 5 are stacked, thereby forming a layer in which the silicon oxide particles 5 are bonded with the binder 6 on the substrate 2 as shown in FIG.

  The dispersion liquid of the silicon oxide particles 5 is a liquid in which the silicon oxide particles are dispersed in a solvent, and the content of the silicon oxide particles is preferably 2% by mass or more and 10% by mass or less. In order to improve the dispersibility of the silicon oxide particles 5, a silane coupling agent or a surfactant may be added to the dispersion of the silicon oxide particles 5. However, when these compounds react with most of the silanol groups on the surface of the silicon oxide particles 5, the bond between the silicon oxide particles 5 and the binder 6 becomes weak, and the wear resistance of the porous layer 3 decreases. Therefore, the additive such as a silane coupling agent and a surfactant is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the silicon oxide particles.

  Since the binder solution has a strong binding force between the silicon oxide particles 5 and the binder 6, it is preferable to use a silicon oxide binder solution. A silicon oxide binder solution is prepared by adding water, an acid or a base to a silicate ester such as methyl silicate or ethyl silicate in a solvent and hydrolyzing and condensing the silicate hydrolysis condensate as a main component. Is preferred. Acids that can be used for the reaction are hydrochloric acid, nitric acid, and the like, and the base is ammonia or various amines, which are selected in consideration of solubility in a solvent and reactivity of a silicate ester. The solution of the silicon oxide binder can also be prepared by neutralizing and condensing a silicate such as sodium silicate in water and diluting with a solvent. Acids that can be used for neutralization are hydrochloric acid, nitric acid and the like.

  A trifunctional silane alkoxide substituted with an organic group such as methyltriethoxysilane or ethyltriethoxysilane can be added to the silicon oxide binder for the purpose of improving solubility and coating properties. The addition amount of the trifunctional silane alkoxide is preferably 10 mol% or less of the entire silane alkoxide. When the addition amount exceeds 10 mol%, the organic group inhibits hydrogen bonding between silanol groups inside the binder, so that the wear resistance is lowered.

  The silicon oxide content in the silicon oxide binder solution is preferably 0.2% by mass or more and 2% by mass or less.

  The solvent that can be used for the dispersion of the silicon oxide particles 5 and the solution of the silicon oxide binder 6 may be any solvent that dissolves the raw material uniformly and does not precipitate the reactant. For example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methylpropanol, 1-pentanol, 2-pentanol, cyclopentanol, 2-methylbutanol, 3-methylbutanol, 1-hexanol, 2-hexanol, 3-hexanol, 4-methyl-2-pentanol, 2-methyl-1-pentanol, 2-ethylbutanol, 2,4-dimethyl-3-pentanol, 3-ethylbutanol , Monovalent alcohols such as 1-heptanol, 2-heptanol, 1-octanol and 2-octanol. Divalent or higher alcohols such as ethylene glycol and triethylene glycol. Ether alcohols such as methoxyethanol, ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, dimethoxyethane, diglyme, Ethers such as tetrahydrofuran, dioxane, diisopropyl ether, cyclopentyl methyl ether. Esters such as ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate. Various aliphatic or alicyclic hydrocarbons such as n-hexane, n-octane, cyclohexane, cyclopentane, and cyclooctane. Various aromatic hydrocarbons such as toluene, xylene, and ethylbenzene. Various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Various chlorinated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, tetrachloroethane. Examples include aprotic polar solvents such as N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, and ethylene carbonate. Two types of solvents can be used in combination.

  Examples of the method for applying the dispersion of the silicon oxide particles 5 and the solution of the silicon oxide binder 6 include spin coating, blade coating, roll coating, slit coating, printing, and dip coating. When manufacturing an optical member having a three-dimensionally complicated shape such as a concave surface, the spin coating method is preferable from the viewpoint of film thickness uniformity.

  After forming the layer in which the silicon oxide particles 5 are bonded with the binder 6, drying and / or curing is performed. Drying and curing are steps for removing the solvent and for promoting the reaction between the silicon oxide binders or between the silicon oxide binder and the silicon oxide particles. The drying and curing temperature is preferably 20 ° C. or higher and 200 ° C. or lower, and more preferably 60 ° C. or higher and 150 ° C. or lower. If the drying and curing temperature is less than 20 ° C., the solvent remains and the wear resistance decreases. On the other hand, if the drying and curing temperature is 200 ° C. or higher, the curing of the binder proceeds excessively, and the binder tends to crack. The drying and curing time is preferably 5 minutes to 24 hours, more preferably 15 minutes to 5 hours. If the drying and curing time is less than 5 minutes, the solvent may partially remain and the in-plane variation of the refractive index may increase, and if it exceeds 24 hours, the binder tends to crack.

  In the case where a dispersion of silicon oxide particles 5 and a silicon oxide binder solution are sequentially applied onto the substrate 2, a step of drying and / or baking can be performed after the dispersion of silicon oxide particles 5 is applied.

  Next, a surface treatment process for alkylsilylating the surfaces of the silicon oxide particles 5 and the binder 6 by exposing the porous layer 3 to an atmosphere containing a silazane compound will be described.

  The porous layer 3 formed on the substrate 2 in the forming step for forming the porous layer is exposed to an atmosphere containing a silazane compound. At this time, the silazane compound contained in the atmosphere is taken into the voids of the porous layer 3 and comes into contact with the surfaces of the silicon oxide particles 5 and the binder 6. Since the silazane (Si—N) bond of the silazane compound is highly reactive, it reacts with silanol (Si—OH) groups present on the surfaces of the silicon oxide particles 5 and the binder 6 to form Si—O—Si bonds. As a result, alkylsilylation is performed to form the porous layer 3.

  Unlike the present invention, in the method of immersing in a silazane compound or silane alkoxide solution, not only the reactivity of the silazane compound and the like is reduced, but also the selective alkylsilylation and silicon oxide particles 5 and the binder are affected by the swelling by the solvent. It is difficult to maintain the skeleton structure with 6. In the alkylsilylation method of the present invention, the silazane compound does not penetrate into the silicon oxide particles 5 or the binder 6. Therefore, as shown in FIG. 5, the porous layer 3 in which the surfaces of the silicon oxide particles 5 and the binder 6 are alkylsilylated while the skeleton of the silicon oxide particles 5 and the binder 6 is maintained can be obtained.

  Examples of silazane compounds that can be used in the present invention include (dimethylamino) trimethylsilane, (diethylamino) trimethylsilane, butyldimethyl (dimethylamino) silane, octyldimethyl (dimethylamino) silane, and diphenylmethyl (dimethylamino) silane. 1,1,1,3,3,3-hexamethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,3-dipropyl-1,1,3,3-tetramethyldisilazane, 1,3-dibutyl-1,1,3,3-ditetramethyldisilazane, 1,3-dioctyl-1,1,3 , 3-tetramethyldisilazane, 1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane, , 3-Diphenyl-1,1,3,3-tetramethyldisilazane, 1,1,3,3-tetraphenyl-1,3-dimethyldisilazane, bis (dimethylamino) dimethylsilane, bis (diethylamino) dimethyl Silane, dimethylbis (s-butylamino) silane, phenylmethylbis (dimethylamino) silane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, 2,4,6-trimethyl-2,4 , 6-trivinylcyclotrisilazane, 2,2,4,4,6,6,8,8-octamethylcyclotetrasilazane, tris (dimethylamino) methylsilane and the like.

  Among the silazane compounds, it is preferable to use a silazane compound represented by the following formula (4) or (5) in that it is highly reactive and an unreacted silazane compound hardly remains.

(In the formula, R4 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R5 and R6 are each independently hydrogen or carbon number. 1 to 3 alkyl groups.)

(In the formula, R7 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R8 is hydrogen or an alkyl group having 1 to 3 carbon atoms. .)

  Specific examples include (dimethylamino) trimethylsilane, (diethylamino) trimethylsilane 1,1,1,3,3,3-hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyl. Disilazane, 1,3-dipropyl-1,1,3,3-tetramethyldisilazane, 1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldi Silazane is mentioned.

  Of the silazane compounds, it is preferable to use a silazane compound represented by the following formula (6) or (7) from the viewpoint of being bifunctional and having a high water repellent effect.

(In the formula, R9 is a monovalent organic group and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms, and R10 and R11 are each independently hydrogen or carbon number. 1 to 3 alkyl groups.)

(In the formula, R12 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R13 is hydrogen or an alkyl group having 1 to 3 carbon atoms. .)

  Specific examples include bis (dimethylamino) dimethylsilane, bis (diethylamino) dimethylsilane, dimethylbis (s-butylamino) silane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, 2 4,6-trimethyl-2,4,6-trivinylcyclotrisilazane.

  As a method of exposing to an atmosphere containing a silazane compound, there are a method of spraying a gas containing a silazane compound onto the porous layer 3, a method of confining the gas containing the silazane compound and the porous layer 3 in a container, and the like. A method of confining the mixed gas containing the silazane compound and the porous layer 3 in the container is preferable in that it can be treated with a small amount of the silazane compound. When processing in a container, it can carry out under atmospheric pressure or pressure reduction, but it is preferable that the density | concentration of the silazane compound in a mixed gas is 5 mg / L or more and 200 mg / L or less.

  When the porous layer 3 is exposed to an atmosphere containing a silazane compound, the temperature is preferably 10 ° C. or more and 60 ° C. or less, and more preferably 20 ° C. or more and 40 ° C. or less. If the temperature of the atmosphere is less than 10 ° C, the concentration of the silazane compound in the atmosphere may be too low to obtain a sufficient water repellent effect. If the temperature exceeds 60 ° C, the porous layer 3 may swell due to an excess silazane compound. There is.

  The exposure time to the atmosphere containing the silazane compound is preferably 0.5 hours or more and 72 hours or less, more preferably 3 hours or more and 24 hours or less, although it depends on the concentration and temperature of the silazane compound in the atmosphere. If the exposure time is less than 0.5 hours, the alkylsilylation may be insufficient and the wear resistance may not be improved. If the exposure time exceeds 72 hours, the silazane compound reacts with water or the like to form a by-product in the porous layer 3. May remain.

  After exposure to an atmosphere containing a silazane compound, a step of removing excess silazane compound in the film may be added. When the volatility of the silazane compound is high, surplus silazane compound is released into the atmosphere only by leaving the porous layer 3 in an atmosphere not containing the silazane compound. When the volatility of the silazane compound is low, the silazane compound may be removed by heating or reduced pressure. When heating to remove the silazane compound, it is preferable to heat at 40 ° C. or higher and 150 ° C. or lower. Further, excess silazane compound can be washed away with a solvent. In that case, it is preferable to use a highly volatile solvent such as methanol, ethanol, or acetone.

Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited by the following examples unless it exceeds the gist.

(Preparation of coating solution)
(1) Preparation of Hollow SiO2 Particle Coating Liquid 1 IPA dispersion of hollow SiO2 particles (through Julia Catalytic Chemical Co., Ltd., Sululia 1110, average particle size 55 nm, solid content concentration 20.50 mass%) Dilution was performed with 28.17 g of methoxy-2-propanol to prepare a hollow SiO2 fine particle coating solution (solid content concentration 3.60% by mass).

(2) Preparation of chain-like SiO2 particle coating solution 2 IPA dispersion of chain-like SiO2 particles (IPA-ST-UP, Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 15% by mass) 6.00 g The solution was diluted with 24.00 g of 1-methoxy-2-propanol to prepare a chain-like SiO2 fine particle coating solution (solid content concentration 3.00% by mass).

(3) Preparation of SiO2 binder coating solution 3 1.7 g of nitric acid (concentration 3.7% by mass) diluted in a solution of 4.17 g of ethyl silicate and 2.30 g of ethanol and 2.30 g of ethanol A solution of was slowly added. After stirring at room temperature for 15 hours, 2.00 g of the measured reaction solution was diluted with 36.33 g of 2-ethyl-1-butanol to prepare SiO2 binder coating solution 3 (solid content concentration 0.6 mass%). did.

(4) Preparation of SiO2 binder coating solution 4 Nitric acid solution (concentration 3.7% by mass) previously diluted in a solution of 3.83 g of ethyl silicate, 0.29 g of methyltriethoxysilane and 2.26 g of ethanol A solution of 1.56 g and 2.26 g of ethanol was slowly added. After stirring at room temperature for 15 hours, 2.00 g of the measured reaction solution was diluted with 37.66 g of 2-ethyl-1-butanol, and a SiO 2 binder coating solution (solid) having a methyl group substituted on Si by 8 mol% was obtained. A partial concentration of 0.6% by mass) was prepared.

(5) Preparation of SiO2 binder coating solution 5 Nitric acid solution (concentration 3.7% by mass) previously diluted in a solution of 3.63 g of ethyl silicate, 0.46 g of methyltriethoxysilane and 2.23 g of ethanol A solution of 1.46 g and 2.23 g of ethanol was slowly added. After stirring for 15 hours at room temperature, 2.00 g of the measured reaction solution was diluted with 38.66 g of 2-ethyl-1-butanol, and a SiO 2 binder coating solution (solid) having a methyl group substituted on Si by 13 mol% was obtained. A partial concentration of 0.6% by mass) was prepared.

(Evaluation)
(6) Measurement of film thickness Using a spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan), the wavelength was measured from 380 nm to 800 nm, and the film thickness was determined from the analysis.

(7) Measurement of refractive index Using a spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan), the wavelength was measured from 380 nm to 800 nm. The refractive index was a refractive index with a wavelength of 550 nm.

(8) Calculation of porosity The volume ratio of the void portion (including the hollow portion of the particle) to the entire film was determined from the refractive index at a wavelength of 550 nm, and was used as the void ratio. The refractive index of the particles (excluding the hollow portion) and the SiO2 binder was 1.45, and the void portion (including the hollow portion of the particle) was 1.0.

(9) Evaluation of abrasion resistance A load of 300 g / cm 2 was applied with a polyester wiper (Alpha wiper TX1009 manufactured by Texwipe), and after 20 reciprocations, the presence or absence of scratches or scratches was observed. Evaluation was made according to the following criteria.
A: There was no change in the sample.
B: The sample was not scratched, but scratch marks are visible.
C: The sample was scratched.

(10) Evaluation of contact angle Using a fully automatic contact angle meter (DM-701, manufactured by Kyowa Interface Science Co., Ltd.), the contact angle when 2 μl of pure water was contacted was measured. The average value obtained by measuring the contact angles three times immediately after the production and after being immersed in pure water for 10 minutes was defined as the water contact angle. Evaluation was made according to the following criteria.
A: 110 ° or more.
B: 100 ° or more and less than 110 °.
C: Less than 100 °.

(11) High-temperature and high-humidity test Changes in the refractive index and the contact angle of pure water after 72 hours in an environmental testing machine (SH-241 manufactured by ESPEC CORP.) Set to 70 ° C / 100% RH were confirmed.
A: The refractive index change is less than 0.01 and there is almost no refractive index change.
B: The refractive index change is 0.01 or more.

(12) Infrared absorption spectrum measurement A 3750 cm-1 silanol-derived peak was observed using an infrared spectrum analyzer (Spectrum One, manufactured by PerkinElmer) and a universal ATR with an attached diamond probe.

Example 1
In Example 1, a suitable amount of a hollow SiO2 fine particle coating solution 1 was dropped on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm, and spin coating was performed at 3000 rpm for 20 seconds. By carrying out, the porous layer which consists of hollow SiO2 microparticles | fine-particles was formed on the base material. Further, an appropriate amount of SiO2 binder coating solution 3 was dropped on the porous layer consisting only of hollow SiO2 fine particles, and spin coating was performed at 4500 rpm for 20 seconds. Then, the porous layer which the hollow SiO2 fine particle couple | bonded with the binder was formed by heating at 140 degreeC for 30 minute (s) in a hot air circulation oven. Further, 0.1 g of 1,1,1,3,3,3-hexamethyldisilazane as a silazane compound was weighed into a 6 ml glass sample tube, and the volume of 610 ml was measured together with the above-mentioned substrate with a porous layer. Placed in a glass container. This glass container was allowed to stand at 23 ° C. for 15 hours in a state of being sealed with a polypropylene lid with a silicone resin packing. Thereafter, the substrate with the porous layer was taken out and left in the air for 30 minutes. It was confirmed that all 1,1,1,3,3,3-hexamethyldisilazane placed in the container volatilized in 15 hours. The concentration of the silazane compound in the container calculated from the volatilization amount was 167 mg / L.

  As a result, an optical member in which a porous layer having a refractive index of 1.24, a porosity of 47%, a film thickness of 124 nm and a water contact angle of 112 ° was formed on a substrate was produced. The contact angle of water after being immersed in pure water for 10 minutes was 110 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Various evaluation results are summarized in Table 1.

  Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

1,1,1,3,3,3-hexamethyldisilazane

Trimethylsilyl group

(Example 2)
In Example 2, an appropriate amount of the chain-like SiO2 fine particle coating solution 2 was dropped on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm, and spin-coated at 3500 rpm for 20 seconds. As a result, a porous layer made only of chain-like SiO2 fine particles was formed on the substrate. Further, an appropriate amount of SiO2 binder coating solution 3 was dropped on the porous layer composed of chain-like SiO2 fine particles, and spin coating was performed at 4500 rpm for 20 seconds. Then, the porous layer which chain | strand-like SiO2 microparticles | fine-particles couple | bonded with the binder was formed by heating for 30 minutes at 140 degreeC in a hot air circulation oven.

  Thereafter, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.25, the porosity was 44%, and the film An optical member in which a porous layer having a thickness of 119 nm and a pure water contact angle of 114 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 112 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

(Example 3)
In Example 3, an appropriate amount of SiO2 binder coating solution 4 was dropped on a porous layer composed only of hollow SiO2 fine particles formed on a glass substrate having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. Then, spin coating was performed at 4500 rpm for 20 seconds. Then, the porous layer which the hollow SiO2 fine particle couple | bonded with the binder was formed by heating at 140 degreeC for 30 minute (s) in a hot air circulation oven.

  Thereafter, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.24, the porosity was 47%, and the film An optical member was produced in which a porous layer having a thickness of 123 nm and a pure water contact angle of 113 ° was formed on a substrate. The contact angle of water after immersion for 10 minutes in pure water was 112 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

Example 4
Example 4 is a porous layer composed only of chain-like SiO2 fine particles formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. Formed. On this porous layer, the SiO2 binder coating solution 4 was coated in the same manner as in Example 2 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Thereafter, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.25, the porosity was 44%, and the film An optical member in which a porous layer having a thickness of 119 nm and a pure water contact angle of 114 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 112 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

(Example 5)
In Example 5, an appropriate amount of SiO2 binder coating solution 5 was dropped on a porous layer composed only of hollow SiO2 fine particles formed on a glass substrate having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. Then, spin coating was performed at 4500 rpm for 20 seconds. Then, the porous layer which the hollow SiO2 fine particle couple | bonded with the binder was formed by heating at 140 degreeC for 30 minute (s) in a hot air circulation oven.

  Thereafter, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.24, the porosity was 47%, and the film An optical member in which a porous layer having a thickness of 122 nm and a contact angle of pure water of 113 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 112 °, and the change was small. Slight wiping marks were observed in the abrasion resistance evaluation. The refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

(Example 6)
For the working collar 6, a porous layer composed only of chain-like SiO2 fine particles is formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 4 in the same manner as in Example 2 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Thereafter, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.24, the porosity was 47%, and the film An optical member was produced in which a porous layer having a thickness of 118 nm and a pure water contact angle of 115 ° was formed on a substrate. The contact angle of water after immersion for 10 minutes in pure water was 114 °, and the change was small. Slight wiping marks were observed in the abrasion resistance evaluation. The refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

(Example 7)
In Example 7, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. . This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was carried out in the same manner as in Example 1, except that 1,1,3,3-tetramethyldisilazane was used as the silazane compound. It was confirmed that all 1,1,3,3-tetramethyldisilazane placed in the container volatilized in 15 hours.

  As a result, an optical member was produced in which a porous layer having a refractive index of 1.24, a porosity of 47%, a film thickness of 123 nm and a pure water contact angle of 126 ° was formed on a substrate. Although the contact angle of water after being immersed in pure water for 10 minutes was 109 ° and the value was high, the change was large. No change was observed in the abrasion resistance evaluation, and the refractive index change in the high temperature and high humidity test was less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilyl groups.

1,1,3,3-tetramethyldisilazane

Dimethylsilyl group

(Example 8)
In Example 8, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was performed using 1,1,3,3-tetramethyldisilazane in the same manner as in Example 7, the refractive index was 1.25, the porosity was 44%, and the film thickness was 118 nm. An optical member in which a porous layer having a contact angle of 127 ° was formed on a substrate was produced. Although the contact angle of water after being immersed in pure water for 10 minutes was 108 ° and the value was high, the change was large. No change was observed in the abrasion resistance evaluation, and the refractive index change in the high temperature and high humidity test was less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilyl groups.

Example 9
In Example 9, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. . This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  Furthermore, alkylsilylation was carried out in the same manner as in Example 1, except that 1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane was used as the silazane compound. went. Of 1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane placed in the container, the amount volatilized in 15 hours is 0.004 g It was confirmed. The concentration of the silazane compound in the container calculated from the volatilization amount was 6.7 mg / L.

  As a result, an optical member in which a porous layer having a refractive index of 1.25, a porosity of 44%, a film thickness of 122 nm, and a pure water contact angle of 112 ° was formed on a substrate was produced. The contact angle of water after being immersed in pure water for 10 minutes was 110 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. From the IR spectrum, the silanol group peak was halved, and it was confirmed that the hollow SiO2 fine particles and the surface of the binder were 3,3,3-trifluoropropyldimethylalkylsilylated.

1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane

3,3,3-trifluoropropyldimethylsilyl group

(Example 10)
In Example 10, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Furthermore, alkylsilylation was carried out using 1,3-bis (3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane in the same manner as in Example 9. Then, an optical member was produced in which a porous layer having a refractive index of 1.26, a porosity of 42%, a film thickness of 119 nm and a pure water contact angle of 112 ° was formed on a substrate. The contact angle of water after being immersed in pure water for 10 minutes was 110 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the peak of the silanol group was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with 3,3,3-trifluoropropyldimethylsilyl groups.

(Example 11)
In Example 11, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. . This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was carried out in the same manner as in Example 1, except that dimethylaminotrimethylsilane was used as the silazane compound. It was confirmed that all dimethylaminotrimethylsilane placed in the container had volatilized in 15 hours.

  As a result, an optical member was produced in which a porous layer having a refractive index of 1.24, a porosity of 47%, a film thickness of 123 nm, and a pure water contact angle of 112 ° was formed on a substrate. The contact angle of water after being immersed in pure water for 10 minutes was 110 °, and the change was small. No change was observed in the abrasion resistance evaluation, and the refractive index change in the high temperature and high humidity test was less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

Dimethylaminotrimethylsilane

Trimethylsilyl group

Example 12
In Example 12, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was carried out using dimethylaminotrimethylsilane in the same manner as in Example 11, and the porosity was a refractive index of 1.25, a porosity of 44%, a film thickness of 118 nm, and a pure water contact angle of 114 °. An optical member having a quality layer formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 112 °, and the change was small. No change was observed in the abrasion resistance evaluation, and the refractive index change in the high temperature and high humidity test was less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with a trimethylsilyl group.

(Example 13)
In Example 13, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. . This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  Furthermore, alkylsilylation was performed in the same manner as in Example 1 except that 0.005 g of bis (dimethylamino) dimethylsilane was measured as a silazane compound. It was confirmed that all the bis (dimethylamino) dimethylsilane placed in the container volatilized in 15 hours. The concentration of the silazane compound in the container calculated from the volatilization amount was 8.4 mg / L. Since excess silazane compound remained on the porous layer, it was washed away with ethanol and then blown dry with dry air.

  As a result, an optical member was produced in which a porous layer having a refractive index of 1.27, a porosity of 40%, a film thickness of 122 nm and a water contact angle of 122 ° was formed on a substrate. The contact angle of water after immersion for 10 minutes in pure water was 121 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilylene groups.

Bis (dimethylamino) dimethylsilane

Dimethylsilylene group

(Example 14)
In Example 14, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was carried out using bis (dimethylamino) dimethylsilane in the same manner as in Example 13, the refractive index was 1.28, the porosity was 38%, the film thickness was 117 nm, and the contact angle of water was 123 °. An optical member having a porous layer formed on a substrate was prepared. The contact angle of water after immersion for 10 minutes in pure water was 122 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilylene groups.

(Example 15)
In Example 15, a porous layer made only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  Furthermore, alkylsilylation was carried out in the same manner as in Example 1 except that 0.005 g of 2,2,4,4,6,6-hexamethylcyclotrisilazane was measured as the silazane compound. It was confirmed that all 2,2,4,4,6,6-hexamethylcyclotrisilazane placed in the container volatilized in 15 hours. The concentration of the silazane compound in the container calculated from the volatilization amount was 8.4 mg / L. Since excess silazane compound remained on the porous layer, it was washed away with ethanol and then blown dry with dry air.

  As a result, an optical member was produced in which a porous layer having a refractive index of 1.25, a porosity of 44%, a film thickness of 123 nm, and a water contact angle of 122 ° was formed on a substrate. The contact angle of water after immersion for 10 minutes in pure water was 121 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilylene groups.

2,2,4,4,6,6-hexamethylcyclotrisilazane

Dimethylsilylene group

(Example 16)
In Example 16, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  Further, alkylsilylation was carried out using 2,2,4,4,6,6-hexamethylcyclotrisilazane in the same manner as in Example 15, the refractive index was 1.26, the porosity was 42%, and the film An optical member in which a porous layer having a thickness of 118 nm and a water contact angle of 123 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 122 °, and the change was small. No change was observed in the wear resistance evaluation, and the refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak was halved, and it was confirmed that the surfaces of the hollow SiO2 fine particles and the binder were substituted with dimethylsilylene groups.

(Comparative Example 1)
In Comparative Example 1, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 1. . This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which the hollow SiO2 fine particles were bonded with a binder.

  An optical member in which a porous layer having a refractive index of 1.23, a porosity of 49%, a film thickness of 124 nm and a water contact angle of 8 ° was formed on a substrate without performing alkylsilylation was prepared. The contact angle of water after being immersed in pure water for 10 minutes was further reduced to less than 5 °. In the wear resistance evaluation, there was a slight scratch. The refractive index change in the high-temperature and high-humidity test greatly exceeded 0.01. Adsorption of moisture and a small amount of organic components in the test layer was confirmed.

(Comparative Example 2)
In Comparative Example 2, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. did. This porous layer was coated with the SiO2 binder coating solution 3 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  An optical member in which a porous layer having a refractive index of 1.24, a porosity of 47%, a film thickness of 118 nm and a water contact angle of 7 ° was formed on a substrate without performing alkylsilylation was prepared. The contact angle of water after being immersed in pure water for 10 minutes was further reduced to less than 5 °. In the wear resistance evaluation, there was a slight scratch. The refractive index change in the high temperature and high humidity test was 0.02. Adsorption of moisture and a small amount of organic components in the test layer was confirmed.

(Comparative Example 3)
In Comparative Example 3, a porous layer composed only of hollow SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 3. . This porous layer was coated with a SiO2 binder coating solution 4 and heated to form a porous layer in which hollow SiO2 fine particles were bonded with a binder.

  An optical member in which a porous layer having a refractive index of 1.23, a porosity of 49%, a film thickness of 123 nm and a water contact angle of 20 ° was formed on a substrate without performing alkylsilylation was prepared. The contact angle of water after being immersed in pure water for 10 minutes was further reduced to 15 °. The abrasion resistance evaluation showed scratches. The refractive index change in the high-temperature and high-humidity test greatly exceeded 0.01. Adsorption of moisture and a small amount of organic components in the test layer was confirmed.

(Comparative Example 4)
In Comparative Example 4, a porous layer composed only of chain-like SiO2 fine particles was formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 4. did. This porous layer was coated with a SiO2 binder coating solution 4 and heated to form a porous layer in which chain-like SiO2 fine particles were bonded with a binder.

  An optical member in which a porous layer having a refractive index of 1.24, a porosity of 47%, a film thickness of 119 nm and a water contact angle of 15 ° was formed on a substrate without performing alkylsilylation was prepared. The contact angle of water after being immersed in pure water for 10 minutes was further reduced to 11 °. The abrasion resistance evaluation showed scratches. The refractive index change in the high-temperature and high-humidity test greatly exceeded 0.01. Adsorption of moisture and a small amount of organic components in the test layer was confirmed.

(Comparative Example 5)
In Comparative Example 5, a porous layer composed only of hollow SiO2 fine particles formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm by the same method as in Example 1 was used. Formed.

  Subsequently, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.20, the porosity was 56%, and the film thickness. An optical member in which a porous layer having a contact angle of water of 112 ° and a contact angle of 112 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 111 °, and the change was small. In the abrasion resistance evaluation, the film was completely peeled off. The refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak disappeared, and since there was no binder, it was confirmed that the surface of the hollow SiO2 fine particles and the binder were alkylsilylated.

(Comparative Example 6)
Comparative Example 6 is a porous layer composed only of chain-like SiO2 fine particles formed on a glass substrate (nd = 1.77, νd = 50) having a diameter (φ) of 30 mm and a thickness of 1 mm in the same manner as in Example 2. Formed.

  Subsequently, alkylsilylation was carried out using 1,1,1,3,3,3-hexamethyldisilazane in the same manner as in Example 1, the refractive index was 1.21, the porosity was 53%, and the film thickness. An optical member in which a porous layer having a water contact angle of 119 nm and a water contact angle of 113 ° was formed on a substrate was produced. The contact angle of water after immersion for 10 minutes in pure water was 111 °, and the change was small. In the abrasion resistance evaluation, the film was completely peeled off. The refractive index change in the high temperature and high humidity test was small and less than 0.01. Further, from the IR spectrum, the silanol group peak disappeared, and since there was no binder, it was confirmed that the surface of the hollow SiO2 fine particles and the binder were alkylsilylated.

(Evaluation of Examples and Comparative Examples)
In the optical members of Examples 1 to 16, the refractive index of the porous layer is as low as 1.24 to 1.25, the contact angle between the surface of the antireflection film (porous layer) and water is 112 to 127, and the water repellency. It has excellent wear resistance. In addition, since the optical members of Examples 1 to 16 are surface alkylsilylated with the silicon oxide particles and the binder, the refractive index change before and after the high temperature and high humidity test is small. In contrast, the optical members of Comparative Examples 1 to 4 that are not alkylsilylated do not have water repellency, are inferior in wear resistance, and are hot and humid as compared to the optical members of Examples 1 to 16. The refractive index change before and after the test is large. The optical members of Comparative Examples 5 and 6 having no binder were inferior in wear resistance as compared with the optical members of Examples 1 to 16.

  The optical member of the present invention can be used for light, for example, an imaging apparatus such as a camera or a video camera, or a projection apparatus such as a liquid crystal projector or an optical scanning device of an electrophotographic apparatus.

DESCRIPTION OF SYMBOLS 1 Optical member 2 Base material 3 Porous layer 4 Antireflection film 5 Silicon oxide particle 6 Binder 7 Oxide layer

Claims (15)

An optical member having a base material and an antireflection film provided on the base material,
The antireflection film has a porous layer on the surface opposite to the substrate,
The porous layer includes a plurality of silicon oxide particles and voids existing between the plurality of silicon oxide particles,
An optical member having an alkylsilyl group represented by the following general formula (2) and / or the following formula (3) on the surface of the silicon oxide particles facing the voids.

(In the formula, R2 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)

(In the formula, R3 is a monovalent organic group, and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms.)   The optical member according to claim 1, wherein the refractive index of the porous layer is 1.19 or more and 1.30 or less.   The optical member according to claim 1, wherein the porous layer has a porosity of 30% or more and 50% or less.   The optical member according to any one of claims 1 to 3, wherein the silicon oxide particles have an average particle diameter of 10 nm or more and 80 nm or less.   5. The optical member according to claim 1, wherein 50% by mass or more of the silicon oxide particles are chain-like particles.   The optical member according to any one of claims 1 to 4, wherein the silicon oxide particles are hollow particles of 50 mass% or more.   7. The optical member according to claim 1, wherein the porous layer has a contact angle between the surface of the porous layer and water of 110 ° or more and 140 ° or less.   The imaging device which has an optical member as described in any one of Claims 1 thru | or 7.   The projection apparatus which has an optical member as described in any one of Claims 1 thru | or 7. A method of manufacturing an optical member,
Forming a porous layer having voids between a plurality of silicon oxide particles on a substrate;
A surface treatment step of alkylsilylating the surface of the silicon oxide particles facing the voids by exposing the porous layer to an atmosphere containing a silazane compound;
The manufacturing method of the optical member characterized by having.   The method of manufacturing an optical member according to claim 10, wherein the forming step includes a step of drying and / or curing after forming the porous layer by a wet method. The method for producing an optical member according to claim 10 or 11, wherein the silazane compound includes a compound represented by the following general formula (4) or (5).

(In the formula, R4 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R5 and R6 are each independently hydrogen or carbon number. 1 to 3 alkyl groups.)

(In the formula, R7 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R8 is hydrogen or an alkyl group having 1 to 3 carbon atoms. .) The method for producing an optical member according to claim 10 or 11, wherein the silazane compound includes a compound represented by the following general formula (6) or (7).

(In the formula, R9 is a monovalent organic group and is a linear or branched alkyl group, alkenyl group, or fluorine alkyl group having 1 to 3 carbon atoms, and R10 and R11 are each independently hydrogen or carbon number. 1 to 3 alkyl groups.)

(In the formula, R12 is a monovalent organic group and is a linear or branched alkyl group having 1 to 3 carbon atoms, an alkenyl group, or a fluorine alkyl group, and R13 is hydrogen or an alkyl group having 1 to 3 carbon atoms. .)   The method for manufacturing an optical member according to any one of claims 10 to 13, wherein the surface treatment step is performed in an atmosphere having a concentration of the silazane compound of 5 mg / L or more and 200 mg / L or less.   The said formation process has a process of apply | coating the solution which has the component for producing | generating a binder or a binder, after apply | coating the dispersion liquid of the said silicon oxide particle, It is any one of Claims 10 thru | or 14 characterized by the above-mentioned. The manufacturing method of the optical member of description.