JP7229691B2 - Optical film and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical film having excellent optical properties and scratch resistance, and a method for producing the same.

Conventionally, in order to suppress reflection at the light input/output interface of an optical element, it has been known to form an antireflection film by laminating optical films having different refractive indices with a thickness of several tens to several hundred nm as a single film or multiple films. It is In order to form these antireflection films, vacuum film forming methods such as vapor deposition and sputtering, and wet film forming methods such as dip coating and spin coating are used.

Materials used for the surface layer of the antireflection film include inorganic materials such as silicon oxide, magnesium fluoride, and calcium fluoride, which are transparent and have a low refractive index, and organic materials such as silicone resin and amorphous fluororesin. It has been known.

In recent years, it has become possible to further reduce the refractive index of the antireflection film by using porous silicon oxide or magnesium fluoride with voids formed in the film, thereby further reducing the reflectance of the optical element. For example, the refractive index can be lowered to 1.27 by providing 30% by volume of voids in a magnesium fluoride thin film having a refractive index of 1.38.

However, when a porous film is used as a film formed on the surface of a substrate, such as an antireflection film provided on the surface of an optical member, dirt such as oil from the surface penetrates into the porous film, may be difficult to wipe off. Therefore, it has been proposed to prevent dirt such as oil from entering the film by attaching a fluororesin to the surface of the antireflection film made of a porous film to increase the water repellency (oil repellency). (Patent Document 1).

JP 2017-54125 A JP 2015-31910 A JP 2016-109999 A JP 2012-76967 A

Adhering a fluororesin to the surface of an antireflection film made of a porous film, as in the optical member described in Patent Document 1, is effective in preventing dirt such as oil from entering the film. is. However, in the optical member described in Patent Document 1, another problem is that the antireflection film provided on the surface is made of a porous film and has a low density. It was found that wiping the surface with a rag may scrape the film and reduce the antireflection performance.

On the other hand, in Patent Document 2, when a hard coat layer made of silicon dioxide and a low-friction layer made of a specific fluorine compound are laminated on the surface of a transparent substrate film, the slidability of the surface is increased and the scratch resistance is improved. stated to improve. However, when the porous film (made of silicon dioxide) described in Patent Document 1 is provided with a fluorine compound that increases slidability as shown in Cited Document 2 instead of the fluororesin, it is applied to the surface. The added fluorine compound diffuses into the porous film, and the slidability of the surface is not improved, and the scratch resistance is not improved. Further, when the added amount of the fluorine compound was increased until good slidability was obtained, the pores of the porous film were covered with the fluorine compound, resulting in deterioration of the optical properties.

SUMMARY OF THE INVENTION In view of such problems in the background art , the present invention aims to solve the problem of providing a member or film that includes a porous film and has excellent scratch resistance.

The present invention comprises a substrate, a porous membrane formed on the substrate, and a dense membrane supporting a fluorine compound provided on the porous membrane , wherein the dense membrane to the surface of the porous film is 30% or more and 70% or less, and the film thickness of the dense film is 10 nm or more and 30 nm or less .
The present invention also provides a method for forming a film, comprising the step of applying a first paint containing at least nanoparticles, a binder and a solvent to the surface of a substrate to form a first film; a step of drying the first film to form a porous film; and a step of applying a second paint comprising a film material and a solvent to a part of the surface of the porous film to form a dense film. and a step of supporting a fluorine compound on the surface of the dense film, wherein the area occupation ratio of the dense film to the surface of the porous film is 30% or more and 70% or less, and the thickness of the dense film is 10 nm or more. The present invention provides a method characterized in that the thickness is 30 nm or less.
The present invention also provides a method for producing a member containing a substrate, comprising the step of preparing the substrate, and applying a first paint containing at least nanoparticles, a binder and a solvent to the surface of the substrate. forming a first film by processing; drying the first film to form a porous film; and a step of supporting a fluorine compound on the surface of the dense film, wherein the area occupation ratio of the dense film to the surface of the porous film is 30. % or more and 70% or less, and the thickness of the dense film is 10 nm or more and 30 nm or less.

According to the present invention, it is possible to provide a member or film having both excellent optical properties and scratch resistance.

FIG. 10 is a schematic cross-sectional view showing an optical film produced in Example 4; 1 is a schematic cross-sectional view showing an optical film produced in Example 1. FIG.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below.
[Optical film]
1 and 2 are schematic cross-sectional views schematically showing one embodiment of the optical film of the present invention.

The optical film 1 of the present invention is formed on a base material 7 , includes a porous film 4 , and has a dense film 5 supporting a fluorine compound 6 on a part of the surface of the porous film 4 .

The porous membrane 4 preferably contains nanoparticles 2 and a binder 3. In this case, the binder 3 binds the nanoparticles 2 to each other or the substrate 7 and the nanoparticles 2, and the nanoparticles 2 or the substrate 7. and nanoparticles 2 are formed. Due to the presence of this void, the optical film of the present invention exhibits a low refractive index.

A dense film 5 exists on a part of the surface of the porous film 4 . Here, the term "dense film" means a film that is not porous (closed without gaps), and a more specific definition will be given below. The dense film 5 supports a fluorine compound 6, and the presence of the fluorine compound 6 gives the optical film 1 of the present invention good slidability. Therefore, from a substantial point of view, the definition of the above-mentioned "dense film" is defined as a "dense film can be said to be

The optical film of the present invention is used for optical members such as optical lenses, optical mirrors, filters, and optical films. Among these, it is preferably used as an antireflection film for an optical lens. That is, a preferred embodiment of the optical film of the present invention is an antireflection film formed on an optical lens that is a transparent substrate. Hereinafter, the porous film 4, the dense film 5, the fluorine compound 6, which are the constituent elements of the optical film 1 of the present invention, and the substrate 7, which is not a constituent element of the optical film 1 but is the basis of its existence, will be described in detail one by one. describe.

(Porous membrane 4)
The porous membrane 4 is a membrane containing the nanoparticles 2 . Examples of films containing nanoparticles 2 include a chain particle film in which solid particles of silicon oxide are linked in a chain, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2017-54125) mentioned above; (JP 2016-109999) described hollow silicon oxide particle film, Patent Document 4 (JP 2012-76967) described porous film obtained using a dispersion containing magnesium fluoride fine particles, etc. is mentioned.

The nanoparticles 2 preferably have an average particle size of 10 nm or more and 80 nm or less, more preferably 12 nm or more and 60 nm or less. If the average particle size of the nanoparticles 2 is less than 10 nm, the voids both between the particles and within the particles become too small, making it difficult to lower the refractive index. On the other hand, if the average particle diameter exceeds 80 nm, the size of the voids between the particles becomes large, so large voids are likely to occur, and scattering occurs due to the particle size, which is not preferable.

Here, the average particle diameter of the nanoparticles 2 is the number average value of the average Feret diameter of each particle. This average Feret's diameter can be measured by image-processing what was observed with a transmission electron microscope. Image processing can be performed using commercially available image processing software such as Image Pro PLUS (manufactured by Media Cybernetics). In a predetermined image area, the contrast is appropriately adjusted if necessary, the average Feret diameter of each particle is measured by particle measurement, and the average value can be calculated.

The nanoparticles 2 may be circular, elliptical, disk-shaped, rod-shaped, needle-shaped, chain-shaped, square, or the like, and may be hollow particles having holes inside. Since the refractive index can be lowered by increasing the porosity of the porous film 4, the nanoparticles should be 50% by weight of hollow particles as shown in FIG. 1 or chain particles as shown in FIG. is preferred, and 80 wt % is more preferred.

A hollow particle is a particle that has a hole inside and a shell covering the outside of the hole. Due to the air contained in the pores (refractive index 1.0), the hollow particles can effectively lower the refractive index of the film compared to particles without pores. The pore may be either single pore or multi-pore, and can be appropriately selected. The shell thickness of the hollow particles is preferably 10% or more and 50% or less, more preferably 20% or more and 35% or less, of the particle diameter (average Feret diameter). If the thickness of the shell is less than 10% of the particle diameter, the strength of the particles will be insufficient, which is not preferable. On the other hand, if the thickness of the shell exceeds 50% of the particle diameter, the effect of lowering the refractive index will not be noticeable, which is not preferable.

On the other hand, chain-like particles are particles in which a plurality of particles are linked in a chain-like or bead-like manner. Even if it becomes a film, the chain-like or bead-like series is maintained, so that the porosity of the porous film 4 can be increased as compared with the case of using single spherical particles. Moreover, since each particle can be made small, large voids are less likely to occur. The number of particles connected in one chain-like particle is 2 or more and 10 or less, preferably 3 or more and 6 or less. If the number of continuous particles exceeds 10, large voids are likely to occur, and the abrasion resistance of the optical film decreases. For particles having a short diameter and a long diameter, such as chain particles, the short diameter is the particle diameter.

Metal oxides such as TiO ₂ , ZnO ₂ , ZrO ₂ can be introduced into the nanoparticles or on the surfaces of the nanoparticles.

The film thickness of the porous film 4 is preferably 80 nm or more and 200 nm or less, more preferably 100 nm or more and 160 nm or less. If the film thickness is less than 80 nm, it is difficult to obtain abrasion resistance, and if it exceeds 200 nm, it becomes difficult to lower the reflectance.

The porosity of the porous membrane 4 is preferably 30% or more and 70% or less. If the porosity is less than 30%, the refractive index may not be lowered sufficiently, and a high antireflection effect may not be obtained.

In order to obtain a sufficient antireflection effect, the refractive index of the porous film 4 is preferably 1.19 or more and 1.32 or less, more preferably 1.22 or more and 1.30 or less.

Moreover, the porous film 4 containing the nanoparticles 2 preferably contains the binder 3 . The binder 3 can be appropriately selected depending on the abrasion resistance, adhesive strength, and environmental reliability of the film. For example, it is preferable to use a silicon oxide binder for a silicon oxide chain particle film.

The content of the binder 3 is preferably 5 wt % or more and 30 wt % or less, more preferably 10 wt % or more and 30 wt % or less, with respect to the porous film 4 .

(Dense film 5)
Examples of materials constituting the dense film 5 in the present invention include silicon oxide binders, polyvinyl acetate and its copolymer resins, ethylene-acetic acid copolymer resins, vinyl chloride-vinyl acetate copolymer resins, urethane resins, and vinyl chloride resins. , chlorinated polypropylene resin, polyamide resin, acrylic resin, maleic acid resin, cyclized rubber resin, polyolefin resin, polystyrene resin, ABS resin, polyester resin, nylon resin, polycarbonate resin, cellulose resin, polylactic acid resin thermosetting resins such as solvent-soluble resins such as phenolic resins, unsaturated polyester resins, and epoxy resins.

The material of the dense film 5 can be appropriately selected depending on the adhesive strength with the porous film 4 and environmental reliability, and the same material as the binder 3 constituting the porous film 4 can be used. However, in that case, since the affinity with the porous membrane 4 increases, it becomes easier to diffuse into the porous membrane 4 when the dense membrane 5 is applied, and it becomes difficult to stay on the surface of the porous membrane 4. , the coating method of the dense film 5, the solvent used for the paint, etc. must be carefully considered.

The area occupation ratio of the dense film 5 to the surface of the porous film 4 is preferably 30% or more and 70% or less, more preferably 40% or more and 65% or less. If the area occupation ratio is less than 30%, the density of the fluorine compound 6 present on the surface of the porous film is too low, resulting in low scratch resistance. .32, which is not very desirable.

The thickness of the dense film 5 is preferably 10 nm or more and 30 nm or less, more preferably 15 nm or more and 25 nm or less. If the film thickness is less than 10 nm, the film will not be flat, and if the film thickness is 30 nm or more, the refractive index of the optical film 1 will exceed 1.32.

As for the flatness of the surface of the dense film 5, the arithmetic mean roughness (Ra) defined in JIS B0601 (1992) is preferably 3 nm or less, more preferably 2 nm or less. When the arithmetic mean roughness of the surface of the dense film 5 is greater than 3 nm, the amount of the fluorine compound that comes into contact with the surface when rubbed with a wiper or the like is small, resulting in insufficient slidability and sufficient scratch resistance. do not have.

(Fluorine compound 6)
In the present invention, preferred examples of the fluorine compound 6 supported on the dense membrane 5 include perfluoropolyether, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy fluororesin (PFA), tetrafluoride Examples thereof include various copolymers of ethylene chloride and propylene hexafluoride, and various polymers having fluoroalkyl pendant groups.

In the present invention, the fluorine compound 6 preferably has a high affinity with the dense film 5, and more preferably forms a chemical bond with the dense film 5 such as a covalent bond or a hydrogen bond. Furthermore, the fluorine compound 6 preferably has a monomolecular film structure called a polymer brush.

(Base material 7)
As the substrate 7 on which the optical film of the present invention is formed, glass, resin, or the like can be used. Moreover, the shape thereof is not limited, and may be flat, curved, concave, convex, film-like, or the like.

A single layer or a plurality of layers such as a high refractive index layer and a medium refractive index layer may be provided between the substrate 7 and the coating surface. Examples of the high refractive index layer and medium refractive index layer include zirconium oxide, titanium oxide, tantalum oxide, niobium oxide, hafnium oxide, alumina, silica, and magnesium fluoride.

A hard coat layer for increasing mechanical strength or a conductive layer may be provided between the substrate and the coating surface.

These high to medium refractive index layers and functional layers can be formed using a vacuum deposition method, a sputtering method, a CVD method, a dip coating method, a spin coating method, a spray coating method, or the like.

[Method for producing an optical film]
An example of the method for manufacturing the optical film 1 of the present invention will be described.

(Method of Forming Porous Film 4)
The method for producing the optical film 1 of the present invention preferably has a forming step of forming the porous film 4 in which the nanoparticles 2 are bound by the binder 3 on the surface of the substrate 7 which is an optical member such as a lens. The porous film 4 may be formed directly on the surface of the substrate 7, or may be formed via a hard coat layer or a conductive layer.

The porous membrane 4 may be formed using either a dry method or a wet method, but it is preferable to use a wet method that allows easy formation of the porous membrane 4 . In order to form the porous film 4 by a wet method, a paint containing nanoparticles and a binder may be prepared and applied by a dip coating method, a spin coating method, a spray coating method, or the like.

The paint for forming the porous membrane 4 preferably contains at least the nanoparticles 2, the binder 3, and the solvent. Then, it is preferable to form a porous film by applying such a coating material on a substrate at a film-forming temperature of 20° C. or higher and 30° C. or lower. At this time, the paint preferably has a viscosity of 1.3 mPa·s or more and 2 mPa·s or less at the film forming temperature. When the viscosity of the paint is within this range, the penetration of the binder into the gaps between the nanoparticles is improved, so that a uniform film containing voids can be formed. In order to allow the binder 3 to permeate the gaps between the nanoparticles, the lower the viscosity of the paint, the better. In addition, a low-viscosity solvent generally has a high vapor pressure, so that it dries quickly at the time of forming a film, and streaks and unevenness are likely to occur. Therefore, it is preferable to select the solvent so that the viscosity of the paint during film formation is 1.3 mPa·s or more and 2 mPa·s or less. The viscosity of the paint is determined by the surface state and concentration of the nanoparticles, the molecular structure of the binder, the molecular weight, the concentration, and the solvent, so the paint should be prepared so that the viscosity falls within the above range.

As the solvent used for the paint, it is possible to appropriately select a solvent having good affinity with the nanoparticles and the binder. If the solvent has a low affinity, the binder will not be compatible, or even if it is compatible as a paint, separation will occur during film formation, resulting in a whitening phenomenon. It is preferable to use a solvent having a boiling point of 100° C. or higher and 200° C. or lower and a viscosity of 2 mPa or lower. Suitable solvents include, for example, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-propoxy-2-propanol, 2-ethyl-2-butanol, methylcel Solve, ethyl cellosolve, butyl cellosolve, etc.

The solvent content in the paint is preferably 95.0 wt % or more and 98.5 wt % or less, preferably 96.0 wt % or more and 98.0 wt % or less. However, depending on the coating method and coating conditions, the content of the solvent should be appropriately adjusted in order to obtain a desired average film thickness, and the range is not limited to this range.

The coating method is not particularly limited, and general coating methods for liquid paints such as dip coating, spin coating, spray coating, and roll coating can be used. However, when it is particularly required to form a uniform film thickness, such as in the case of forming an antireflection film on the surface of the lens substrate, it is possible to form the film by applying the paint by a spin coating method. preferable.

After coating, the coating film is dried. A dryer, a hot plate, an electric furnace, or the like can be used for drying. Drying conditions are such that the organic solvent in the nanoparticles can be evaporated without affecting the substrate. Since there is a difference in thermal expansion coefficient between the substrate and the optical film 1, it is generally preferable to use a temperature of 200° C. or less so that the optical film 1 does not peel off or crack when dried at high temperatures. The number of times of coating is usually preferably once, but drying and coating may be repeated multiple times.

(Method for Forming Dense Film 5)
Either a dry method or a wet method may be used to form the dense film 5 on the surface of the porous film 4, but the wet method may be used to form the dense film 5 simply. In the wet method, the material constituting the dense film is dissolved in a solvent and diluted appropriately to adjust the concentration to prepare a paint. It is possible to form a dense film on the film. A method of transferring a coating film formed on another substrate may also be used.

In the optical film of the present invention, the dense film 5 is formed so as to exist on part of the surface of the porous film 4 (with an area occupation ratio of 30% or more and 70% or less). The area occupancy of the dense film is determined by the concentration of the film material in the paint and the applied amount of the film material, such as the amount of dropping (in the case of the spin coating method), the spray time (in the case of the spray coating method), or the amount of ejection (in the case of the inkjet method). You can adjust by changing

Moreover, when the dense film 5 is formed, the degree of penetration into the porous film 4 changes depending on the viscosity when it adheres to the porous film 4 . If the viscosity of the paint is too low, the paint will diffuse inside the porous membrane 4, which is not preferable. On the other hand, if the viscosity is too high, the paint of the dense film 5 clumps on the surface of the porous film 4, resulting in a high haze, which is also not preferable. A preferred form is a form in which the material of the membrane 5 remains on the surface of the porous membrane 4 and the recesses on the surface of the porous membrane 4 are flattened.

After forming the coating film of the dense film 5, the coating film is dried. A dryer, a hot plate, an electric furnace, or the like can be used for drying. Drying conditions are such that the organic solvent in the nanoparticles can be evaporated without affecting the substrate. As in the case of forming the porous film 4, there is a difference in thermal expansion coefficient between the base material 7 and the optical film 1, so that the optical film 1 is not peeled off or cracked by high-temperature drying. Drying at a temperature of 200° C. or less is preferred. The number of times of film formation is usually preferably once, but drying and film formation may be repeated multiple times.

(Method for Supporting Fluorine Compound 6)
After forming the dense film 5 on the porous film 4, in order to support (attach) the fluorine compound 6 on the surface thereof, a solution of the fluorine compound 6 is applied by a spin coating method, a blade coating method, a roll coating method, or a slit coating method. It may be applied by a commonly used method such as a method, a printing method, a dip coating method, or the like. As the solvent used for the solution of the fluorine compound, it is preferable to select a solvent having high compatibility with the fluorine compound. Preferred examples of solvents used for the fluorine compound solution include fluorine-containing organic solvents such as hydrofluoroethers and perfluorocarbons, mixed solvents thereof, and mixed solvents of these and other organic solvents. The concentration of the fluorine compound in the solution is preferably 0.05 wt % or more and 1 wt % or less.

The fluorine compound provided on the dense film 5 is supported on the surface without passing through the dense film 5, and contributes to the improvement of the scratch resistance of the optical film 1 by exhibiting good slidability. . On the other hand, the fluorine compound 6 applied to the portion where the dense film 5 is not formed is applied to the surface of the porous film 4 and partly penetrates into the porous film through the pores on the surface. It doesn't help you fully express your sexuality. However, in the optical film of the present invention, since the dense film 5 is present in the area of 30% to 70% of the surface of the porous film 4, sufficiently good slidability is exhibited as a whole.

After applying the fluorine compound solution, the coating film is dried. A dryer, a hot plate, an electric furnace, or the like can be used for drying. After all, it is generally preferable to dry at a temperature of 200° C. or less so that the optical film 1 is not peeled off or cracked by drying at a high temperature.

EXAMPLES The preparation of the optical film of the present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

(Preparation of paint)
(1) Preparation of paint 1 containing chain-like SiO ₂ particles 2-propanol (IPA) dispersion of chain-like SiO ₂ particles in which solid SiO ₂ particles are linked in chains (IPA-ST- manufactured by Nissan Chemical Industries, Ltd.) UP (registered trademark), particle size 40 to 100 nm; dynamic light scattering method, solid content concentration 15 wt%). Replace most of the 2-propanol with 1-propoxy-2-propanol (manufactured by Sigma) in an evaporator. Thus, a 1-propoxy-2-propanol dispersion of chain-like SiO ₂ particles was prepared. The solvent ratio was 2-propanol:1-propoxy-2-propanol=7.5:92.5.

18.5 g of tetraethoxysilane (TEOS, manufactured by Tokyo Chemical Industry Co., Ltd.) and 16.0 g of 0.1 wt % phosphinic acid, which is 10 equivalents to TEOS as catalyst water, were combined and mixed in a water bath at 20° C. for 60 minutes. A binder solution 1 was prepared by stirring.

To 251.3 g of the 1-propoxy-2-propanol dispersion of the chain-shaped SiO ₂ particles prepared above, 32.8 g of the binder solution 1 prepared above (the components necessary to form the binder in terms of oxide 0.5 wt%), and furthermore, 174.5 g of 1-propoxy-2-propanol and 546 g of ethyl lactate were added in order to make the solid content concentration of the chain SiO ₂ particles 4.3 wt% in terms of oxide. 5 g was added and stirred for 60 minutes to prepare paint 1 containing chain-like SiO ₂ particles. The solvent ratio in the prepared paint 1 was 1-propoxy-2-propanol:ethyl lactate=40:60.

(2) Preparation of paint 2 containing hollow SiO2 particles ₂ -propanol (IPA) dispersion of hollow _SiO2 particles (Sururia 1110 manufactured by Nikki Shokubai Kasei Co., Ltd., average particle size 55 nm, solid content concentration 20.50 wt%)6 A paint containing hollow SiO ₂ particles (3.60 wt% solids concentration) 2 was prepared by diluting .00 g with 28.17 g of 1-methoxy-2-propanol (PGME). Particle size distribution measurement by dynamic light scattering (Zetasizer Nano ZS, Malvern) confirmed that hollow _SiO2 particles with a particle size of 55 nm were dispersed.

(3) Preparation of Paint 3 Containing Hollow MgF ₂ Particles 100 g of isooctane, 10 g of bis(2-ethylhexyl)sodium sulfosuccinate (AOT) as a surfactant, and 7 g of water were combined and stirred for 1 hour to form water particles (liquid) of 9 nm. A solution (dispersion) was prepared in which water-in-oil micelles were formed.

To the obtained solution, 3 g of a mixed solution of tetrabutylammonium difluorotriphenylsilicate (TBAT) at a concentration of 5 wt % in phenyl methyl ether and 1 g of AOT were added to dissolve TBAT in the oil layer. Further, 3 g of a solution of magnesium ethoxide mixed in phenyl methyl ether at a concentration of 1 wt % and 1 g of AOT were added and mixed, followed by stirring at 60° C. for 1 hour to synthesize magnesium fluoride.

40 ml of ethanol was added to the magnesium fluoride synthesized solution to separate it into a hydrophilic solvent and a hydrophobic solvent. When the former was taken out and dried and observed with a scanning transmission electron microscope, hollow particles with a particle diameter of 10 nm were confirmed. The hollow particles were dispersed in 10 ml of Teflon AF2400.

(4) Preparation of SiO ₂ binder paint 4 To 7.7 g of 1-ethoxy-2-propanol (manufactured by Kishida Chemical Co., Ltd.), 26.0 g of tetraethoxysilane (TEOS, manufactured by Tokyo Chemical Industry Co., Ltd.) and as catalyst water 22.5 g of 0.01 M diluted hydrochloric acid, which is 10 equivalents to TEOS, was added and mixed and stirred for 60 minutes. Further, a binder solution 1 was prepared by stirring in an oil bath at 60° C. for 40 minutes. Thereafter, 1-ethoxy-2-propanol and 2-ethylbutanol were added so that the solid content concentration of silicon oxide was finally 1.0 wt %. The ratio of 1-ethoxy-2-propanol and 2-ethylbutanol in the binder solution was 3/7.

(5) Preparation of SiO ₂ binder paint 5 Except that 1-ethoxy-2-propanol and 2-ethylbutanol were added so that the final silicon oxide solid content concentration was 1.2 wt%, (4) and A similar treatment was performed.

(6) Preparation of SiO ₂ binder paint 6 Except that 1-ethoxy-2-propanol and 2-ethylbutanol were added so that the final silicon oxide solid content concentration was 1.5 wt%, (4) and A similar treatment was performed.

(7) Preparation of SiO ₂ binder paint 7 Except that 1-ethoxy-2-propanol and 2-ethylbutanol were added so that the final silicon oxide solid content concentration was 0.5 wt%, (4) and A similar treatment was performed.

(evaluation)
(8) Measurement of Film Thickness of Optical Film 1 A spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan) was used to measure from wavelengths of 380 nm to 800 nm, and the film thickness was obtained from analysis.

(9) Measurement of Refractive Index of Optical Film 1 A spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan) was used to measure the refractive index from 380 nm to 800 nm. The refractive index was the refractive index at a wavelength of 550 nm. The low refractive index properties were evaluated according to the following criteria.
A: When the refractive index is 1.30 or less B: When the refractive index is 1.32 or less C: When the refractive index is greater than 1.32

(10) Evaluation of Scratch Resistance of Optical Film 1 Using AR-30 (manufactured by Ozu Sangyo Co., Ltd.), the surface of the film was rubbed back and forth 10 times at 150 g/cm ² , and then scratches were visually confirmed. If no damage was visually observed, the surface of the film was rubbed with 200 g/cm ² to confirm the damage. This evaluation was repeated by increasing the load by 50 g/cm ² until scratches were observed, and the scratch resistance was evaluated according to the following criteria based on the maximum load at which no scratches were observed.
A: when the maximum load is 300 g/cm ² or more B: when the maximum load is 200 g/cm ² or more C: when the maximum load is less than 200 g/cm ²

(11) Calculation method of area occupation ratio of dense film 5 (pretreatment)
Using a metal sputtering device (108Act, manufactured by Cressington), the sample surface was coated with Au--Pd at 30 mA for 50 seconds.

(observation)
Using FE-SEM (Sigma500VP, manufactured by Carl Zeiss Microscopy), the surface was observed at a magnification of 20,000. The acceleration voltage was set to 3 kV. After capturing the SE image of the observation point, the observation point was moved so as not to overlap the observation point, and photography was performed again. This operation was repeated so as to obtain two images in the vertical direction and three images in the horizontal direction. The obtained images were processed by Image-Pro Plus software (manufactured by Media Cybernetotics) in the following procedure.
(1) The image area was selected.
(2) "Optimal matching" was performed.
(3) A spatial filter (Sobel) was applied.
(4) A low-pass filter (3×3) was implemented. As for the conditions at that time, the number of times: 2 times and the strength: 10 were applied.
(5) A place (dark color) with a dense film was selected to measure the area ratio. (Detected size: 10 ³ to 10 ⁷ times)
(6) (1) to (5) were performed for the number of images, and the average of the obtained area ratios was calculated.
Since the 20,000-fold image has a length of 12 μm and a width of 15 μm, the area obtained by arranging two images vertically and three images horizontally is 840 μm ² . In the present invention, this area is defined as a unit area.

(12) Determination of Thickness of Dense Film 5 Pretreatment and observation were performed under the following treatment conditions.
(Preprocessing)
A carbon film and a Pt—Pd film were coated on the observation sample.
Carbon film coat: NC-5Turbo made by Enomoto AV (60 seconds x 6 times)
Pt-Pd film coat: Hitachi E-1030 (15 mA, 60 seconds x 4 times)

(observation)
FIB processing: FEI Nova600 (FIB processing: 30 kV)
Cross-sectional STEM observation: Hitachi S-5500 (accelerating voltage: 30 kV)

(Film thickness calculation method)
A 200,000-fold DF image of the cross section obtained from the observation was processed by Image-Pro Plus software (manufactured by Media Cybernetotics) according to the following procedure.
(1) Converted to an 8-bit image.
(2) Binarized with Threshold.
(3) From the obtained image, the distance of the portion corresponding to the dense membrane 5 was measured, and the thickness was calculated from the magnification.
(4) Measurements were taken at 10 different locations, and the average value was taken as the thickness.

(13) How to Obtain Arithmetic Mean Roughness Ra The surface of the observation sample was observed with SPM (L-trace & NanoNaviII, manufactured by SII Nanotechnology), and the portion where the dense film 5 was formed was measured. After the measurement, the film-formed portion was selected and Ra was measured.

(Example 1)
In Example 1, an appropriate amount of paint 1 containing chain-like _SiO2 particles was dropped onto a Si substrate having a diameter (φ) of 30 mm and a thickness of 0.5 mm, and spin coating was performed at 3500 rpm for 20 seconds to obtain a coating on the substrate. A porous film consisting of chain-like _SiO2 particles was formed on the substrate. The SiO ₂ binder paint 4 was applied by spraying for 40 seconds onto the formed porous film composed of chain-like SiO ₂ particles. Further, 0.06 ml of a fluorine compound solution (FG-5083SH manufactured by Fluoro Technology Co., Ltd., solid content concentration 0.10 wt %) was dropped and spin-coated at 1000 rpm for 20 seconds, and then spin-coated at 2000 rpm for 10 seconds. After that, by heating in a hot air circulation oven at 120 ° C for 20 minutes, a dense film partially exists on the porous film of chain-like _SiO2 particles, and a film with a fluorine compound attached on the dense film (Fig. 2) was formed.

As a result, an optical film having a refractive index of 1.290 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 42% and a film thickness of 22 nm. The scratch resistance of this optical film was 250 g. Various evaluation results are summarized in Table 1.

In addition, the depth direction component analysis of the film by XPS shows that fluorine is concentrated on the surface of the film, and a large amount of carbon is found in a shallow portion from the surface of the film, indicating that a fluorine compound is present on the porous film. was confirmed.

(Example 2)
Example 2 was treated under the same conditions as in Example 1, except that the spray time of the SiO ₂ binder paint 4 was changed to 80 seconds. As a result, an optical film having a refractive index of 1.316 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 68% and a film thickness of 24 nm. The scratch resistance of this optical film was 300 g.

(Example 3)
Example 3 was treated under the same conditions as Example 1, except that the spray time of the SiO ₂ binder paint 4 was changed to 30 seconds. As a result, an optical film having a refractive index of 1.274 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 32% and a film thickness of 18 nm. The scratch resistance of this optical film was 200 g.

(Example 4)
In Example 4, the treatment was carried out under the same conditions as in Example 1, except that Paint 2 containing hollow SiO ₂ particles was used instead of Paint 1 containing chain SiO ₂ particles. As a result, an optical film (FIG. 1) having a refractive index of 1.280 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 40% and a film thickness of 20 nm. The scratch resistance of this optical film was 200 g.

(Example 5)
In Example 5, paint 3 containing hollow _MgF2 particles was spin coated at 4000 rpm for 20 seconds. A SiO ₂ binder paint 4 was spray-coated for 40 seconds on the formed porous membrane consisting of hollow MgF ₂ particles. Furthermore, 0.06 ml of a fluorine compound solution (FG-5083SH manufactured by Fluoro Technology Co., Ltd., solid content concentration 0.10 wt %) was added dropwise and spin-coated at 1000 rpm for 20 seconds, and then spin-coated at 2000 rpm for 10 seconds. After that, by heating for 20 minutes at 120°C in a hot air circulation oven, a dense film was partially present on the porous film of the hollow _MgF2 particles, and a film with a fluorine compound attached on the dense film was formed. .

As a result, an optical film having a refractive index of 1.319 and a film thickness of 120 nm was produced. The dense film had an area occupation ratio of 34% and a film thickness of 22 nm. The scratch resistance of this optical film was 250 g.

(Example 6)
In Example 6, the same procedure as in Example 1 was performed except that SF Coat KS14A (manufactured by AGC Seichemical Co., Ltd.) was used instead of the fluorine compound solution (FG-5083SH, solid content concentration 0.10 wt% manufactured by Fluoro Technology Co., Ltd.). processed under the conditions. As a result, an optical film having a refractive index of 1.310 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 40% and a film thickness of 24 nm. The scratch resistance of this optical film was 250 g.

(Example 7)
In Example 7, the treatment was carried out under the same conditions as in Example 1 except that the SiO ₂ binder coating 5 was used instead of the SiO ₂ binder coating 4 . As a result, an optical film having a refractive index of 1.318 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 32% and a film thickness of 30 nm. The scratch resistance of this optical film was 250 g.

(Comparative example 1)
In Comparative Example 1, the treatment was carried out under the same conditions as in Example 1, except that the spray time of the SiO ₂ binder paint 4 was changed to 100 seconds. As a result, an optical film having a refractive index of 1.335 and a thickness of 100 nm was produced. The dense film had an area occupation ratio of 75% and a film thickness of 22 nm. The scratch resistance of this optical film was 350 g.

(Comparative example 2)
In Comparative Example 2, the treatment was performed under the same conditions as in Example 1, except that the spray time was changed to 20 seconds. As a result, an optical film having a refractive index of 1.265 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 10% and a film thickness of 22 nm. The scratch resistance of this optical film was 150 g.

(Comparative Example 3)
In Comparative Example 3, the treatment was carried out under the same conditions as in Example 2, except that the fluorine compound solution was not applied. A dense film is partially present on the porous film of chain-like _SiO2 particles, but no fluorine compound film is formed thereon. As a result, an optical film having a refractive index of 1.290 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 68% and a film thickness of 24 nm. The scratch resistance of this optical film was 100 g.

(Comparative Example 4)
In Comparative Example 4, the treatment was performed under the same conditions as in Example 1 except that the SiO ₂ binder coating 6 was used instead of the SiO ₂ binder coating 4 . As a result, an optical film having a refractive index of 1.328 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 32% and a film thickness of 38 nm. The scratch resistance of this optical film was 200 g.

(Comparative Example 5)
In Comparative Example 5, the treatment was carried out under the same conditions as in Example 1, except that SiO ₂ binder paint 7 was used instead of SiO ₂ binder paint 4 . As a result, an optical film having a refractive index of 1.265 and a film thickness of 100 nm was produced. The dense film had an area occupation ratio of 68% and a film thickness of 8 nm. The scratch resistance of this optical film was 100 g.

The conditions and results of Examples 1-7 and Comparative Examples 1-5 are summarized in Table 1 below.

The optical member of the present invention can be used for imaging equipment such as cameras and video cameras, or projection equipment such as optical scanning devices for liquid crystal projectors and electrophotographic equipment.

1 optical film 2 nanoparticles 3 binder 4 porous film 5 dense film 6 fluorine compound 7 substrate

Claims (26)

a substrate;
a porous film formed on the substrate ;
a dense film provided on the porous film and supporting a fluorine compound,
A member , wherein the area occupation ratio of the dense film to the surface of the porous film is 30% or more and 70% or less, and the film thickness of the dense film is 10 nm or more and 30 nm or less. 2. The member according to claim 1, wherein said fluorine compound is attached to the surface of said dense membrane opposite to said porous membrane. 3. The member according to claim 1, wherein the porous film has a thickness of 80 nm or more and 200 nm or less. 4. The member according to any one of claims 1 to 3, wherein the area occupation ratio of the dense membrane to the surface of the porous membrane is 40% or more and 65% or less. 5. The member according to claim 1, wherein the dense film has a thickness of 15 nm or more and 25 nm or less. 6. The member according to any one of claims 1 to 5, wherein the dense film has a surface arithmetic mean roughness of 3 nm or less. 7. A member according to any one of the preceding claims, characterized in that the dense membrane is composed of a silicon oxide binder or a resin. 6. The member according to any one of claims 1 to 5, characterized in that said porous membrane comprises nanoparticles and a binder. 9. The member according to claim 8, wherein the nanoparticles have an average particle size of 10 nm or more and 80 nm or less. 10. The member according to claim 8, wherein the nanoparticles are hollow particles or chain particles. 11. The member according to any one of claims 8 to 10, wherein the nanoparticles are hollow particles, and the shell thickness of the hollow particles is 10% or more and 50% or less of the average particle diameter. 12. A member according to any one of claims 8 to 11, characterized in that said nanoparticles comprise metal oxides or magnesium fluoride. 13. A member according to claim 12, characterized in that said nanoparticles are particles of silicon oxide. 14. A member according to claim 12 or 13, characterized in that said binder is a silicon oxide binder. 15. The member according to any one of claims 1 to 14, wherein the fluorine compound has a monomolecular film structure. 16. The member according to any one of claims 1 to 15, wherein the porous film has a refractive index of 1.19 or more and 1.32 or less. 17. The member according to any one of Claims 1 to 16, wherein the substrate is in the form of a film . 17. The member according to any one of claims 1 to 16, characterized in that said base material is a transparent base material. 17. The member according to any one of claims 1 to 16 , characterized in that said substrate is a lens. An imaging device comprising the member according to any one of claims 1 to 19 as an optical member . A projection apparatus comprising the member according to any one of claims 1 to 19 as an optical member . A method of forming a membrane, comprising:
A step of applying a first paint containing at least nanoparticles , a binder and a solvent to the surface of a substrate to form a first film, and drying the first film to form a porous film. forming a dense film by applying a second paint comprising a film material and a solvent to a part of the surface of the porous film; and supporting a fluorine compound on the surface of the dense film. have
A method, wherein the area occupation ratio of the dense film to the surface of the porous film is 30% or more and 70% or less, and the film thickness of the dense film is 10 nm or more and 30 nm or less. A method for manufacturing a member containing a base material,
A step of preparing the base material, a step of applying a first coating containing at least nanoparticles , a binder and a solvent to the surface of the base material to form a first film, and the first film forming a porous film by drying; forming a dense film by applying a second coating comprising a film material and a solvent to a part of the surface of the porous film; and a step of supporting a fluorine compound on the surface ,
A method, wherein the area occupation ratio of the dense film to the surface of the porous film is 30% or more and 70% or less, and the film thickness of the dense film is 10 nm or more and 30 nm or less. 24. The method according to claim 22 or 23 , wherein the step of forming the first film is performed at 20[deg.]C or higher and 30[deg.]C or lower. 25. Any one of claims 22 to 24 , wherein in the step of forming the first film, the viscosity of the first coating material during coating is 1.3 mPa·s or more and 2 mPa·s or less. 1. The method according to item 1 . 26. The method according to any one of claims 22 to 25 , wherein in the step of forming the dense film, a silicon oxide binder paint is used as the second paint.

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