(en)An optical component includes a base material and an antireflection film containing silica particles, wherein the silica particles have a first local maximum in the range of 1.5 nm or more and 2.5 nm or less (a first range), a second local maximum in the range of 3.5 nm or more and 4.5 nm or less (a second range), and a third local maximum in the range of 7.5 nm or more and 8.5 nm or less (a third range) in a number-based particle size distribution. It is preferred that the silica particles have a fourth local maximum in the range of 5.5 nm or more and 6.5 nm or less in the number-based particle size distribution.

1.ApplicationNumber: US-201514930805-A
1.PublishNumber: US-9348063-B1
2.Date Publish: 20160524
3.Inventor: FURUSATO DAIKI
SUZUKI KATSUMI

4.Inventor Harmonized: FURUSATO DAIKI(JP)
SUZUKI KATSUMI(JP)

5.Country: US
6.Claims:
(en)An optical component includes a base material and an antireflection film containing silica particles, wherein the silica particles have a first local maximum in the range of 1.5 nm or more and 2.5 nm or less (a first range), a second local maximum in the range of 3.5 nm or more and 4.5 nm or less (a second range), and a third local maximum in the range of 7.5 nm or more and 8.5 nm or less (a third range) in a number-based particle size distribution. It is preferred that the silica particles have a fourth local maximum in the range of 5.5 nm or more and 6.5 nm or less in the number-based particle size distribution.

7.Description:
(en)BACKGROUND
1. Technical Field
The present invention relates to an optical component and a timepiece.
2. Related Art
In an optical component such as a cover glass for a timepiece, an antireflection film which prevents light reflection is provided for the purpose of enhancing visibility on an opposite surface side or the like.
In the related art, an optical component had a complicated structure such that many layers are stacked on one another for obtaining a sufficient antireflection function (see, for example JP-A-2010-37115). Further, in the related art, each layer constituting an antireflection film is formed by a chemical vapor deposition and therefore, the productivity of the optical component is poor, and also the production cost is high.
SUMMARY
An advantage of some aspects of the invention is to provide an optical component including an antireflection film having an excellent antireflection function with a simple structure, and also to provide a timepiece including the optical component.
An optical component according to an aspect of the invention includes a base material and an antireflection film containing silica particles, wherein the silica particles have a first local maximum in the range of 1.5 nm or more and 2.5 nm or less, a second local maximum in the range of 3.5 nm or more and 4.5 nm or less, and a third local maximum in the range of 7.5 nm or more and 8.5 nm or less in a number-based particle size distribution.
According to this configuration, an optical component including an antireflection film having an excellent antireflection function with a simple structure can be provided.
In the optical component according to the aspect of the invention, it is preferred that the ratio of the silica particles having a particle diameter of 1.5 nm or more and 2.5 nm or less to the sum of the volumes of the silica particles constituting the antireflection film is 5% by volume or more and 30% by volume or less.
According to this configuration, the antireflection film can be made relatively dense while making the antireflection function of the antireflection film particularly excellent, and the strength of the antireflection film and the durability of the optical component can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the ratio of the silica particles having a particle diameter of 3.5 nm or more and 4.5 nm or less to the sum of the volumes of the silica particles constituting the antireflection film is 10% by volume or more and 40% by volume or less.
According to this configuration, the antireflection film can be made relatively dense while making the antireflection function of the antireflection film particularly excellent, and the strength of the antireflection film and the durability of the optical component can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the ratio of the silica particles having a particle diameter of 7.5 nm or more and 8.5 nm or less to the sum of the volumes of the silica particles constituting the antireflection film is 30% by volume or more and 60% by volume or less.
According to this configuration, the antireflection film can be made relatively dense while making the antireflection function of the antireflection film particularly excellent, and the strength of the antireflection film and the durability of the optical component can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the silica particles have a fourth local maximum in the range of 5.5 nm or more and 6.5 nm or less in the number-based particle size distribution.
According to this configuration, the antireflection function of the antireflection film can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the ratio of the silica particles having a particle diameter of 5.5 nm or more and 6.5 nm or less to the sum of the volumes of the silica particles constituting the antireflection film is 20% by volume or more and 30% by volume or less.
According to this configuration, the antireflection film can be made relatively dense while making the antireflection function of the antireflection film particularly excellent, and the strength of the antireflection film and the durability of the optical component can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the thickness of the antireflection film is 50 nm or more and 120 nm or less.
According to this configuration, the durability, antireflection function, and the like of the optical component can be made particularly excellent.
In the optical component according to the aspect of the invention, it is preferred that the base material is composed of a material containing at least one member selected from the group consisting of a silicate glass, a sapphire glass, and a plastic.
These materials have excellent transparency, and therefore, the optical property of the optical component can be made particularly excellent. Further, in the case where an antireflection film is provided on a base material composed of such a material, the antireflection function attributed to the antireflection film is more effectively exhibited.
In the optical component according to the aspect of the invention, it is preferred that the optical component is a cover glass for a timepiece.
The cover glass is present at a place close to the viewpoint of an observer (a user or the like) at the time of using a timepiece, and also time-displaying members such as a dial plate and hands are generally disposed on a rear surface side of the cover glass, and therefore, the cover glass (optical component) is a member which is strongly required to have visibility of a dial plate and the like through the cover glass (optical component). Therefore, in the case where the aspect of the invention with which a high antireflection function is exhibited is applied to a cover glass, the effect of the aspect of the invention is more remarkably exhibited.
Further, the cover glass is a component which has many opportunities to be visually recognized by an observer (a user or the like), and has a large influence on the appearance of the entire timepiece. In the aspect of the invention, a high antireflection function is exhibited, and therefore, the excellent appearance (aestheticity) inherent in an ornamental component such as a dial plate which is visually recognized through the cover glass can be effectively exhibited. Therefore, by applying the aspect of the invention to a cover glass for a timepiece, the aesthetic appearance of the timepiece as a whole can be made particularly excellent.
A timepiece according to an aspect of the invention includes the optical component according to the aspect of the invention.
According to this configuration, a timepiece capable of favorably visually recognizing a state on a rear surface side of the optical component can be provided, and the aesthetic appearance (aestheticity) of the timepiece as a whole can be made excellent, and thus, the value as an ornament can be increased. Further, for example, the visibility of the time and the like can be improved, and thus, also the function (practicality) as a utility article becomes excellent.
According to the aspects of the invention, an optical component including an antireflection film having a sufficient antireflection function with a simple structure can be provided, and also a timepiece including the optical component can be provided.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
FIG. 1 is a cross-sectional view schematically showing a first embodiment of an optical component according to the invention.
FIG. 2 is a view schematically showing one example of a particle size distribution of silica particles constituting an antireflection film of an optical component according to the invention.
FIG. 3 is a cross-sectional view schematically showing a second embodiment of an optical component according to the invention.
FIG. 4 is a partial cross-sectional view showing a preferred embodiment of a timepiece (wristwatch) according to the invention.



DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
Optical Component
First, an optical component according to the invention will be described.
First Embodiment
FIG. 1 is a cross-sectional view schematically showing a first embodiment of an optical component according to the invention, and FIG. 2 is a view schematically showing one example of a particle size distribution of silica particles constituting an antireflection film of an optical component according to the invention.
As shown in FIG. 1 , an optical component P 10 of this embodiment includes a base material P 1 and an antireflection film P 2 containing silica particles P 21 .
The silica particles P 21 contained in the antireflection film P 2 have a given particle size distribution.
That is, the silica particles P 21 contained in the antireflection film P 2 have a first local maximum MV 1 in the range of 1.5 nm or more and 2.5 nm or less (a first range R 1 ), a second local maximum MV 2 in the range of 3.5 nm or more and 4.5 nm or less (a second range R 2 ), and a third local maximum MV 3 in the range of 7.5 nm or more and 8.5 nm or less (a third range R 3 ) in a number-based particle size distribution (see FIG. 2 ).
Because of having such a particle size distribution, an excellent antireflection function is obtained. In particular, with a very simple structure as compared with an antireflection film in the related art, an excellent antireflection function is obtained.
The reason why such an excellent antireflection function is obtained is considered to be because by including the silica particles P 21 having a particle size distribution as described above, the refractive index is decreased as compared with silica in a bulk form, and thus, a favorable optical interference effect is exhibited.
Further, by including the silica particles P 21 having a particle size distribution as described above, the optical component P 10 has an excellent antifogging property. As a result, a decrease in the optical property due to dew condensation or the like can be reliably prevented.
The reason why such an excellent antifogging property is obtained is considered to be because by including the silica particles P 21 having a particle size distribution as described above, a fine fractal structure is favorably formed.
Further, in the related art, an antireflection function is sometimes exhibited by providing a resin film which can be formed easily, however, such a resin film has a problem that not only the antireflection function is low but also the abrasion resistance is low, and for example, when dirt adheres to the surface of the optical component, a wiping operation cannot be performed, and the like. On the other hand, the antireflection film P 2 as described above has also excellent abrasion resistance, and therefore, a wiping operation can also be favorably performed.
Such an antireflection film P 2 can be more easily formed by, for example, a coating method or the like as described in detail later.
Due to this, the optical component P 10 having an excellent antireflection function and the like can be obtained with high productivity without using a large and expensive apparatus. Further, the production cost of the optical component P 10 can also be decreased.
Further, the density (the filling ratio of the silica particles P 21 ) of the antireflection film P 2 can be made high, and thus, the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made excellent.
Base Material
The base material P 1 constitutes a main part of the optical component P 10 and is generally a member which has light transmittance.
The refractive index of the base material P 1 for a light with a wavelength of 589 nm is preferably 1.43 or more and 1.85 or less, more preferably 1.45 or more and 1.78 or less.
According to this, the optical property of the optical component P 10 can be made particularly excellent.
The constituent material of the base material P 1 is not particularly limited, and for example, various glasses, various plastics, and the like can be used. However, it is preferably a material containing at least one member selected from the group consisting of a silicate glass (a quartz glass or the like), a sapphire glass, and a plastic.
These materials have excellent transparency. Further, in the case where the antireflection film P 2 is provided on the base material P 1 composed of such a material, the antireflection function attributed to the antireflection film P 2 is more effectively exhibited.
In particular, in the case where the base material P 1 contains at least one of a silicate glass and a sapphire glass, excellent optical properties such as particularly excellent light transmittance and a moderate refractive index are obtained, and also the adhesiveness thereof to the antireflection film P 2 is made particularly excellent, and thus, the durability of the optical component P 10 as a whole can be made particularly excellent.
Examples of a plastic material constituting the base material P 1 include various thermoplastic resins and various thermosetting resins, and specific examples thereof include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymers, and ethylene-vinyl acetate copolymers (EVA), cyclic polyolefins (COP), modified polyolefins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamides (for example, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, and nylon 6-66), polyimides, polyamideimides, polycarbonate (PC), poly-(4-methylpentene-1), ionomers, acrylic resins, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymers (ABS resins), acrylonitrile-styrene copolymers (AS resins), butadiene-styrene copolymers, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymers (EVOH), polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PET), and polycyclohexane terephthalate (PCT), polyether, polyether ketone (PEK), polyether ether ketone (PEEK), polyether imide, polyacetal (POW, polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, aromatic polyesters (liquid crystal polymers), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, various thermoplastic elastomers such as styrene-based, polyolefin-based, polyvinyl chloride-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, trans-polyisoprene-based, fluororubber-based, and chlorinated polyethylene-based elastomers, epoxy resins, phenolic resins, urea resins, melamine resins, unsaturated polyesters, silicone-based resins, urethane-based resins, poly-para-xylylene resins such as poly-para-xylylene, poly-monochloro-para-xylylene, poly-dichloro-para-xylylene, poly-monofluoro-para-xylylene, and poly-monoethyl-para-xylylene, and also include copolymers, blends, and polymer alloys composed mainly of these materials. Among these, one type or two or more types in combination (for example, as a blend resin, a polymer alloy, a stacked body, or the like) can be used.
Antireflection Film
The antireflection film P 2 is composed of a material containing a plurality of silica particles P 21 having a given particle size distribution.
That is, the silica particles P 21 have a first local maximum Mill in the range of 1.5 nm or more and 2.5 nm or less (a first range R 1 ), a second local maximum MV 2 in the range of 3.5 nm or more and 4.5 nm or less (a second range R 2 ), and a third local maximum MV 3 in the range of 7.5 nm or more and 8.5 nm or less (a third range R 3 ) in a number-based particle size distribution.
The ratio of the silica particles P 21 having a particle diameter of 1.5 nm or more and 2.5 nm or less (the ratio of the silica particles P 21 falling within the first range R 1 ) to the sum of the volumes of the silica particles P 21 constituting the antireflection film P 2 is preferably 5% by volume or more and 30% by volume or less, more preferably 10% by volume or more and 25% by volume or less.
According to this, the antireflection film P 2 can be made relatively dense while making the antireflection function of the antireflection film P 2 particularly excellent, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
The ratio of the silica particles P 21 having a particle diameter of 3.5 nm or more and 4.5 nm or less (the ratio of the silica particles P 21 falling within the second range R 2 ) to the sum of the volumes of the silica particles P 21 constituting the antireflection film P 2 is preferably 10% by volume or more and 40% by volume or less, more preferably 15% by volume or more and 35% by volume or less.
According to this, the antireflection film P 2 can be made relatively dense while making the antireflection function of the antireflection film P 2 particularly excellent, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
The ratio of the silica particles P 21 having a particle diameter of 7.5 nm or more and 8.5 nm or less (the ratio of the silica particles P 21 falling within the third range R 3 ) to the sum of the volumes of the silica particles P 21 constituting the antireflection film P 2 is preferably 30% by volume or more and 60% by volume or less, more preferably 35% by volume or more and 55% by volume or less.
According to this, the antireflection film P 2 can be made relatively dense while making the antireflection function of the antireflection film P 2 particularly excellent, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
In the number-based particle size distribution, the range of the particle diameter in which the first local maximum MV 1 is present may be 1.5 nm or more and 2.5 nm or less, but is preferably 1.6 nm or more and 2.4 nm or less, and more preferably 1.8 nm or more and 2.2 nm or less.
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
In the number-based particle size distribution, the range of the particle diameter in which the second local maximum MV 2 is present may be 3.5 nm or more and 4.5 nm or less, but is preferably 3.6 nm or more and 4.4 nm or less, and more preferably 3.8 nm or more and 4.2 nm or less.
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
In the number-based particle size distribution, the range of the particle diameter in which the third local maximum MV 3 is present may be 7.5 nm or more and 8.5 nm or less, but is preferably 7.6 nm or more and 8.4 nm or less, and more preferably 7.8 nm or more and 8.2 nm or less.
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
The silica particles P 21 may have the above-mentioned first local maximum MV 1 , second local maximum MV 2 , and third local maximum MV 3 in the number-based particle size distribution, but preferably have a fourth local maximum MV 4 in the range of 5.5 nm or more and 6.5 nm or less (a fourth range R 4 ).
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
The ratio of the silica particles P 21 having a particle diameter of 5.5 nm or more and 6.5 nm or less (the ratio of the silica particles P 21 falling within the fourth range R 4 ) to the sum of the volumes of the silica particles P 21 constituting the antireflection film P 2 is preferably 20% by volume or more and 30% by volume or less, more preferably 22% by volume or more and 28% by volume or less.
According to this, the antireflection film P 2 can be made relatively dense while making the antireflection function of the antireflection film P 2 particularly excellent, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
In the number-based particle size distribution, the range of the particle diameter in which the fourth local maximum MV 4 is present may be 5.5 nm or more and 6.5 nm or less, but is preferably 5.6 nm or more and 6.4 nm or less, and more preferably 5.8 nm or more and 6.2 nm or less.
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
The number-based average particle diameter of the silica particles P 21 constituting the antireflection film P 2 is not particularly limited, but is preferably 0.5 nm or more and 4.0 nm or less, more preferably 1.0 nm or more and 2.0 nm or less.
According to this, the antireflection film P 2 can be made relatively dense while making the antireflection function of the antireflection film P 2 particularly excellent, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
In the embodiment of the invention, the measurement of the particle size distribution can be performed by using various methods, for example, a dynamic light scattering method, a laser diffraction method, an image analysis method, a gravity sedimentation method, and the like, but is preferably performed by using a laser diffraction method.
According to this, the particle size distribution can be obtained more easily. Further, in either case of a dry process or a wet process, the measurement can be favorably performed, and a relatively large amount of a sample can be treated at a time.
Examples of an apparatus which can be used for measuring the particle size distribution include a single nanoparticle size analyzer (IG-1000) manufactured by Shimadzu Corporation.
The content of the silica particles P 21 in the antireflection film P 2 (the content thereof to the total solid components) is preferably 80% by volume or more, more preferably 90% by volume or more and 99.5% by volume or less, further more preferably 92% by volume or more and 99% by volume or less.
According to this, the antireflection function of the antireflection film P 2 can be made particularly excellent.
The antireflection film P 2 may be any as long as it contains the silica particles P 21 having a particle size distribution as described above, however, in the configuration shown in the drawing, it contains conductive particles P 22 .
When the antireflection film P 2 contains the conductive particles P 22 in this manner, an antistatic function is exhibited in the optical component P 10 as a whole. As a result, for example, the adhesion of dust or the like due to static electricity can be prevented, and thus, the optical component P 10 can stably exhibit the inherent optical property. Further, in the case where the optical component P 10 including such an antireflection film P 2 is used as a member for a timepiece such as a cover glass for a timepiece, the deformation of a hand such as an hour hand due to static electricity can be more reliably prevented. As a result, a breakdown or the like of a timepiece including the member for a timepiece can be more effectively prevented. Such an antistatic function is obtained by using the silica particles P 21 and the conductive particles P 22 in combination, and is not obtained, for example, in the case where an antireflection film composed of a multilayer film having a plurality of dense layers (layers formed by a gas-phase deposition method) as in the related art and conductive particles are used in combination.
The conductive particles P 22 may be any as long as it is composed of a material with electrical conductivity, however, the volume resistivity of the constituent material of the conductive particles P 22 is preferably 100 Ωcm or less.
According to this, the antistatic property of the optical component P 10 can be made particularly excellent.
Further, the conductive particles P 22 are preferably composed of a transparent material.
According to this, the visibility through the optical component P 10 can be more reliably prevented from being adversely affected.
Further, the conductive particles P 22 are preferably composed of a metal oxide. The metal oxide generally has excellent chemical stability, and therefore can stably exhibit an antistatic function over a long period of time, and thus, the durability of the optical component P 10 can be made particularly excellent.
Examples of the constituent material of the conductive particles P 22 satisfying the above-mentioned conditions include In 2 O 3 , ZnO, CdO, Ga 2 O 3 , and SfO 2 , materials obtained by doping any of the above-mentioned compounds with tin (Sn), antimony (Sb), aluminum (Al), gallium (Ga), or the like (for example, ITO (Sn-doped In 2 O 3 ), AZO (Al-doped ZnO), GZO (Ga-doped ZnO), and the like), and materials containing two or more compounds selected therefrom (for example, IZO (In 2 O 3 —ZnO), IGZO (In 2 O 3 —Ga 2 O 3 —ZnO), and the like). Above all, as the constituent material of the conductive particles P 22 , SnO 2 is preferred. SnO 2 not only has high transparency, but also has a relatively low refractive index, and therefore, has a few effects on the antireflection property. Further, SnO 2 is relatively inexpensive, and SnO 2 particles having a particle diameter as described later can be easily and stably obtained.
The number-based average particle diameter of the conductive particles P 22 is not particularly limited, but is preferably 0.3 nm or more and 10 nm or less, more preferably 0.7 nm or more and 6.0 nm or less, furthermore preferably 1.0 nm or more and 3.0 nm or less.
According to this, the antistatic function can be made particularly excellent while making the antireflection function of the antireflection film P 2 excellent. Further, the antireflection film P 2 can be made relatively dense, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
When the number-based average particle diameter of the silica particles P 21 is represented by Ds (nm) and the number-based average particle diameter of the conductive particles P 22 is represented by Dc (nm), it is preferred to satisfy the following relationship: 0.1≦Dc/Ds≦0.6, it is more preferred to satisfy the following relationship: 0.2≦Dc/Ds≦0.5, and it is further more preferred to satisfy the following relationship: 0.3≦Dc/Ds≦0.4.
By satisfying such a relationship, a mixing state of the silica particles P 21 and the conductive particles P 22 in the antireflection film P 2 can be made more favorable, and the antistatic function of the optical component P 10 can be made particularly excellent. Further, the antireflection film P 2 can be made relatively dense, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent. In addition, the antireflection function and the like of the antireflection film P 2 can also be made particularly excellent.
The content of the conductive particles P 22 in the antireflection film P 2 (the content thereof to the total solid components) is preferably 0.5% by volume or more and 10% by volume or less, more preferably 1.0% by volume or more and 8.0% by volume or less.
According to this, the antistatic function can be made particularly excellent while making the antireflection function of the antireflection film P 2 excellent. Further, the antireflection film P 2 can be made relatively dense, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
When the content of the silica particles P 21 in the antireflection film P 2 (the content thereof to the total solid components) is represented by Xs (vol %) and the content of the conductive particles P 22 in the antireflection film P 2 (the content thereof to the total solid components) is represented by Xc (vol %), it is preferred to satisfy the following relationship: 0.003≦Xc/Xs≦0.12, and it is more preferred to satisfy the following relationship: 0.005≦Xc/Xs≦0.1.
According to this, the antistatic function can be made particularly excellent while making the antireflection function of the antireflection film P 2 excellent. Further, the antireflection film P 2 can be made relatively dense, and the strength of the antireflection film P 2 and the durability of the optical component P 10 can be made particularly excellent.
The antireflection film P 2 may contain a component other than the above-mentioned components.
Examples of such a component include an antifungal agent, a preservative, an antioxidant, an ultraviolet absorber, a binder, and a slipping agent (leveling agent).
The porosity of the antireflection film P 2 is preferably 15% by volume or more and 36% by volume or less, more preferably 18% by volume or more and 32% by volume or less.
According to this, the antireflection function can be made particularly excellent while making the durability of the optical component P 10 as a whole sufficiently excellent. In this manner, the reason why the antireflection film has a particularly excellent antireflection function is because in the antireflection film P 2 , pores (air layers (refractive index: 1.00)) are present along with a region occupied by the silica particles P 21 (refractive index: 1.46) at a given ratio, so that the refractive index is decreased as compared with silica in a bulk form, and as a result, a favorable optical interference effect is obtained. Further, in the case where the antireflection film P 2 contains the conductive particles P 22 , the antistatic function as described above is more remarkably exhibited.
The porosity of the antireflection film P 2 refers to the ratio of pores accounting for the entire volume of the antireflection film P 2 , and the pore encompasses not only a space provided among particles constituting the antireflection film P 2 , but also a hole provided inside the particle.
The surface roughness Ra of the antireflection film P 2 is preferably 0.5 nm or more and 10.0 nm or less, more preferably 0.7 nm or more and 6.0 nm or less.
According to this, the antifogging property of the optical component P 10 can be made particularly excellent while making the light transmittance of the optical component P 10 as a whole sufficiently excellent.
The thickness of the antireflection film P 2 is preferably 50 nm or more and 120 nm or less, more preferably 60 nm or more and 100 nm or less.
According to this, the durability, antireflection function, and the like of the optical component P 10 can be made particularly excellent while effectively preventing the optical property of the optical component P 10 from being adversely affected.
Examples of the optical component include various lenses (including microlenses, lenticular lenses, fresnel lenses, and the like) such as projector lenses, camera lenses, and eyeglass lenses, filters (camera low-pass filters, and the like), light transmitting plates, dust-proof glasses, radiator plates, cover glasses for timepieces, rear lids for timepieces, and light transmitting dial plates (for example, dial plates for solar timepieces).
Among these, the optical component is preferably a cover glass for a timepiece.
The cover glass is present at a place close to the viewpoint of an observer (a user or the like) at the time of using a timepiece, and also time-displaying members such as a dial plate and hands are generally disposed on a rear surface side of the cover glass, and therefore, the cover glass (optical component) is a member which is strongly required to have visibility of a dial plate and the like through the cover glass (optical component). Therefore, in the case where the invention with which a high antireflection function is exhibited is applied to a cover glass, the effect of the invention is more remarkably exhibited.
Further, the cover glass is a component which has many opportunities to be visually recognized by an observer (a user or the like), and has a large influence on the appearance of the entire timepiece. In the embodiment of the invention, a high antireflection function is exhibited, and therefore, the excellent appearance (aestheticity) inherent in an ornamental component such as a dial plate which is visually recognized through the cover glass can be effectively exhibited. Therefore, by applying the embodiment of the invention to a cover glass for a timepiece, the aesthetic appearance of the timepiece as a whole can be made particularly excellent.
Further, in a diver's watch or the like, liquid tightness in a case is maintained, however, a humidity contained in the case when assembling the watch is dew-condensed during use to cause a problem of decreasing the visibility in some cases. However, according to the embodiment of the invention, the antireflection film has a high antireflection function and also has a high antifogging property, and therefore, for example, in a diver's watch, by disposing a cover glass (optical component), to which the embodiment of the invention is applied, such that a surface provided with the antireflection film faces the inner surface side, the problem of dew condensation as described above can be more reliably prevented.
Second Embodiment
FIG. 3 is a cross-sectional view schematically showing a second embodiment of the optical component according to the invention. In the following description, different points from the above embodiment will be mainly described, and the description of the same matter will be omitted.
As shown in FIG. 3 , an optical component P 10 of this embodiment includes abase material P 1 , an antireflection film P 2 containing silica particles P 21 , and a foundation layer P 3 .
In this manner, by including the foundation layer P 3 , for example, the adhesiveness between the base material P 1 and the antireflection film P 2 (the adhesiveness through the foundation layer P 3 ) can be made particularly excellent, and thus, the durability and reliability of the optical component P 10 can be made particularly excellent.
Examples of a constituent material of the foundation layer P 3 include various resin materials and SiO 2 .
The thickness of the foundation layer P 3 is not particularly limited, but is preferably 5 nm or more and 25 nm or less, more preferably 10 nm or more and 20 nm or less.
In the configuration shown in the drawing, only one foundation layer P 3 is formed, however, the optical component P 10 may include a plurality of foundation layers between the base material P 1 and the antireflection film P 2 .
Method for Producing Optical Component
Next, a method for producing the optical component will be described.
The optical component P 10 may be produced by any method, but can be favorably produced by, for example, using a method including a base material preparation step ( 1 a ) of preparing a base material P 1 , an antireflection film forming composition application step ( 1 b ) of applying an antireflection film forming composition containing silica particles P 21 and a dispersion medium for dispersing the silica particles P 21 onto the base material P 1 , and a dispersion medium removal step ( 1 c ) of removing the dispersion medium from the antireflection film forming composition applied onto the base material P 1 .
Base Material Preparation Step
In this step, a base material P 1 is prepared ( 1 a ).
As the base material P 1 , a material described above can be used, however, a material subjected to a pretreatment such as a washing treatment or a lyophilization treatment may be used. Further, as the pretreatment, a mask may be formed in a region where the antireflection film P 2 is not desired to be formed. In this case, as a post-treatment step, a mask removal step may be included.
Antireflection Film Forming Composition Application Step
In this step, an antireflection film forming composition containing silica particles P 21 and a dispersion medium for dispersing the silica particles P 21 is applied onto the base material P 1 ( 1 b ).
Such an antireflection film forming composition contains a dispersion medium and has excellent fluidity, and therefore, the antireflection film P 2 in which an undesirable variation in the thickness is more effectively prevented can be easily and reliably formed.
Examples of the method for applying the antireflection film forming composition onto the base material P 1 include various printing methods such as an inkjet method, various coating methods such as roll coating, spray coating, spin coating, and brush coating, and dipping (a dipping method).
The dispersion medium constituting the antireflection film forming composition may be any as long as it has a function to disperse the silica particles P 21 , however, examples thereof include water; alcohol-based solvents such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, and glycerin; ketone-based solvents such as methyl ethyl ketone and acetone; glycol ether-based solvents such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether; glycol ether acetate-based solvents such as propylene glycol 1-monomethyl ether 2-acetate and propylene glycol 1-monoethyl ether 2-acetate; polyethylene glycol and polypropylene glycol, and one type or a combination of two or more types selected from these solvents can be used.
Among these, as the dispersion medium, water, an alcohol-based solvent, or a glycol-based solvent (in addition to a glycol such as ethylene glycol or propylene glycol, a compound such as an ether, an ester, or the like of a glycol such as a glycol ether-based solvent or a glycol ether acetate-based solvent) is preferred.
According to this, the dispersion stability of the silica particles P 21 and the like in the antireflection film forming composition can be made particularly excellent, and the occurrence of an undesirable variation in the composition in the antireflection film P 2 to be formed and an undesirable variation in the thickness thereof can be more effectively prevented.
In particular, in the case where the antireflection film forming composition is applied by a method such as roll coating or spin coating, it is preferred to use water or an alcohol-based solvent as the dispersion medium.
According to this, the coatability of the antireflection film forming composition on the base material P 1 can be made particularly excellent.
In the case where the antireflection film forming composition is applied by a method such as spray coating, it is preferred to use a glycol-based solvent as the dispersion medium.
According to this, the coatability of the antireflection film forming composition onto the base material P 1 can be made particularly excellent. Further, clogging can be prevented, and thus, the productivity and the like of the optical component P 10 can be made particularly high.
The antireflection film forming composition may contain a component (another component) other than the silica particles P 21 and the dispersion medium. Examples of such a component (another component) include conductive particles, an antifungal agent, a preservative, an antioxidant, an ultraviolet absorber, a binder, and a slipping agent (leveling agent).
The content of the silica particles P 21 in the antireflection film forming composition is not particularly limited, but is preferably 0.5% by mass or more and 10% by mass or less.
According to this, the fluidity of the antireflection film forming composition can be made favorable, and the occurrence of an undesirable variation in the thickness or the like in the antireflection film P 2 to be formed can be more effectively prevented, and also the efficiency of forming the antireflection film P 2 can be made particularly excellent, and thus, the productivity of the optical component P 10 can be made particularly high.
The content of the dispersion medium in the antireflection film forming composition is not particularly limited, but is preferably 90% by mass or more and 99.5% by mass or less.
According to this, the fluidity of the antireflection film forming composition can be made favorable, and the occurrence of an undesirable variation in the thickness or the like in the antireflection film P 2 to be formed can be more effectively prevented, and also the efficiency of forming the antireflection film P 2 can be made particularly excellent, and thus, the productivity of the optical component P 10 can be made particularly high.
The viscosity of the antireflection film forming composition in this step as measured according to JIS Z 8809 using a vibration-type viscometer is preferably 20 mPa·s or less, more preferably 3 mPa·s or more and 15 mPa·s or less.
According to this, the application of the antireflection film forming composition onto the base material P 1 can be favorably performed, and the occurrence of an undesirable variation in the thickness or the like in the antireflection film P 2 to be formed can be more effectively prevented, and also the efficiency of forming the antireflection film P 2 can be made particularly excellent, and thus, the productivity of the optical component P 10 can be made particularly high.
Dispersion Medium Removal Step
In this step, the dispersion medium is removed from the antireflection film forming composition applied onto the base material P 1 ( 1 c ).
According to this, the antireflection film P 2 strongly bonded to the base material P 1 is formed. In particular, the antireflection film forming composition contains particles (silica particles P 21 ) as a constituent component of the antireflection film P 2 .
Due to this, when the dispersion medium is removed in this step, the occurrence of a phenomenon that the dispersion medium is undesirably enclosed in the antireflection film P 2 to be formed so that the dispersion medium undesirably remains in the optical component P 10 to be finally obtained can be reliably prevented. As a result, the optical property and reliability of the optical component P 10 can be reliably made excellent. Further, since the antireflection film forming composition contains particles (silica particles P 21 ) as a constituent component of the antireflection film P 2 , the dispersion medium contained in the antireflection film forming composition in the form of a film can be maintained in a state where it communicates with the outside constantly in this step, and therefore, the dispersion medium can be efficiently removed from the antireflection film forming composition in the form of a film. As a result, the productivity of the optical component P 10 can be made high.
This step can be performed by, for example, a heating treatment, a vacuum treatment, an air blowing treatment, or the like, and two or more treatments selected therefrom may be performed in combination.
In the case where this step is performed by a heating treatment, the heating temperature is preferably 50° C. or higher and 200° C. or lower, more preferably 60° C. or higher and 180° C. or lower. Further, the heating temperature in this step is preferably lower than the boiling point of the dispersion medium of the antireflection film forming composition.
According to this, the antireflection film P 2 can be efficiently formed while preventing undesirable deterioration, denaturation, or the like of the material, or undesirable deformation or the like of the antireflection film P 2 or the like.
In the case where this step is performed by a vacuum treatment, the pressure during the vacuum treatment (the pressure of the environment in which the base material P 1 having the antireflection film forming composition applied thereon is placed) is preferably 1×10 2 Pa or less, more preferably 1×10 1 Pa or less.
According to this, the productivity of the optical component P 10 can be made particularly high. Further, the occurrence of an adverse effect caused by the dispersion medium remaining in the finally obtained optical component P 10 can be more reliably prevented.
In this step, for example, two or more treatments under different conditions may be performed.
For example, a first heating treatment which is performed at a relatively low temperature and a second heating treatment which is performed at a higher temperature than in the first heating treatment may be performed. According to this, while more effectively preventing the occurrence of a defect (for example, the occurrence of a relatively large pore, undesirable deformation of the antireflection film P 2 , or the like) or the like in the antireflection film P 2 to be formed, the efficiency of forming the antireflection film P 2 can be made particularly excellent.
The antireflection film forming composition application step and the dispersion medium removal step may be performed repeatedly. According to this, even an antireflection film having a relatively large thickness can be favorable formed. In addition, the antireflection film P 2 can be favorably formed at a plurality of places on the base material P 1 . For example, even in the case where the antireflection film P 2 is formed at a plurality of places where it is difficult to apply the antireflection film forming composition by performing a single antireflection film forming composition application step, or in the case where the antireflection films P 2 having a different condition, for example, having a different thickness are formed, etc., this production method can be favorably applied.
Further, as shown in FIG. 3 , in the case where the optical component P 10 having the foundation layer P 3 between the base material P 1 and the antireflection film P 2 is produced, for example, by providing a foundation layer forming material application step of applying a foundation layer forming material onto the base material P 1 prior to the antireflection film forming composition application step, the optical component P 10 can be favorably produced.
In the case where the foundation layer P 3 containing a resin material is formed, as the foundation layer forming material, a material obtained by dissolving the resin material in a solvent, a liquid composition containing a precursor (for example, a monomer, a dimer, a trimer, an oligomer, a prepolymer, or the like) of the resin material can be used.
In the case where such a material is used, examples of the method for applying the foundation layer forming material include various printing methods such as an inkjet method, various coating methods such as roll coating, spray coating, spin coating, and brush coating, and dipping (a dipping method).
Further, in the case where the foundation layer P 3 composed of, for example, SiO 2 is formed, a foundation layer formation step of forming the foundation layer P 3 on the surface of the base material P 1 by a gas-phase deposition method (for example, a vapor deposition method) may be provided prior to the antireflection film forming composition application step. According to this, the adhesiveness between the base material P 1 and the foundation layer P 3 can be made particularly excellent, and also the transparency of the foundation layer P 3 can be made particularly high, and thus, the optical property of the optical component P 10 as a whole can be further enhanced.
According to the production method as described above, an optical component including an antireflection film having an excellent antireflection function with a simple structure can be efficiently produced.
Timepiece
Next, a timepiece according to the invention will be described.
The timepiece according to the invention includes the optical component according to the invention as described above.
According to this, a timepiece capable of favorably visually recognizing a state on a rear surface side of the optical component can be provided, and the aesthetic appearance (aestheticity) of the timepiece as a whole can be made excellent, and thus, the value as an ornament can be increased. In addition, for example, the visibility of the time and the like can be improved, and therefore, also the function (practicality) as a utility article becomes excellent.
The timepiece according to the invention may be any as long as it includes the optical component according to the invention as at least one optical component, and as the other components, known components can be used, however, hereinafter, one example of the configuration of the timepiece when the optical component according to the invention is applied to the cover glass will be representatively described.
FIG. 4 is a partial cross-sectional view showing a preferred embodiment of the timepiece (wristwatch) according to the invention.
As shown in FIG. 4 , a wristwatch (portable timepiece) P 100 of this embodiment includes a barrel (case) P 82 , a rear lid P 83 , a bezel (frame) P 84 , and a cover glass (a cover glass for a timepiece) P 85 . In the case P 82 , a dial plate for a timepiece (a dial plate) P 7 , a solar cell P 94 , and a movement P 81 are housed, and further, hands (indicator hands) not shown in the drawing and the like are also housed.
The cover glass P 85 is composed of the optical component according to the invention as described above.
According to this, the visibility of the dial plate P 7 , the hands (indicator hands), and the like can be enhanced. Further, the dial plate P 7 and the like are members which have a large influence on the appearance of the entire timepiece, however, undesirable light reflection when the dial plate P 7 and the like are visually recognized is prevented, and therefore, the aesthetic appearance (aestheticity) of the timepiece as a whole can be made particularly excellent.
The movement P 81 drives the indicator hands by utilizing the electromotive force of the solar cell P 94 .
Although not shown in FIG. 4 , in the movement P 81 , for example, an electric double-layer capacitor which stores the electromotive force of the solar cell P 94 , a lithium ion secondary buttery, a crystal oscillator as a time reference source, a semiconductor integrated circuit which generates a driving pulse for driving the timepiece based on the oscillation frequency of the crystal oscillator, a step motor for driving the indicator hands every second by receiving this driving pulse, a gear train mechanism for transmitting the movement of the step motor to the indicator hands, and the like are included.
Further, the movement P 81 includes an antenna for receiving a radio wave (not shown), and has a function to perform time adjustment and the like using the received radio wave.
The solar cell P 94 has a function to convert light energy into electrical energy. The electrical energy converted by the solar cell P 94 is utilized for driving the movement P 81 or the like.
The solar cell P 94 has, for example, a PIN structure in which a p-type impurity and an n-type impurity are selectively introduced into a non-single crystal silicon thin film, and further, an i-type non-single crystal silicon thin film having a low impurity concentration is provided between a p-type non-single crystal silicon thin film and an n-type non-single crystal silicon thin film.
In the barrel P 82 , a winding stem pipe P 86 is fitted and fixed, and in this winding stem pipe P 86 , a shaft P 871 of a stem P 87 is rotatably inserted.
The barrel P 82 and the bezel P 84 are fixed to each other with a plastic packing P 88 , and the bezel P 84 and the cover glass P 85 are fixed to each other with a plastic packing P 89 .
In the barrel P 82 , the rear lid P 83 is fitted (or threadedly engaged), and in a joint portion (seal portion) P 93 of these members, a ring-shaped rubber packing (rear lid packing) P 92 is inserted in a compressed state. According to this configuration, the seal portion P 93 is sealed in a liquid-tight manner, whereby a water-proof function is obtained.
A groove P 872 is formed in a middle part on an outer periphery of the shaft P 871 of the stem P 87 , and in this groove P 872 , a ring-shaped rubber packing (stem packing) P 91 is fitted. The rubber packing P 91 is in close contact with the inner peripheral surface of the winding stem pipe P 86 and compressed between the inner peripheral surface and the inner surface of the groove P 872 . According to this configuration, liquid-tight sealing is provided between the stem P 87 and the winding stem pipe P 86 , so that a water-proof function is obtained. Incidentally, when the stem P 87 is rotated, the rubber packing P 91 rotates along with the shaft P 871 and slides in the circumferential direction while being in close contact with the inner peripheral surface of the winding stem pipe P 86 .
In the above description, as one example of the timepiece, a timepiece including a cover glass as the optical component according to the invention has been described, however, the timepiece according to the invention may be a timepiece including, for example, a component to which the optical component according to the invention is applied as the component other than the cover glass. For example, the rear lid or the like may be one composed of the optical component according to the invention. According to this, the effect as described above can be obtained, and also the aesthetic appearance (aestheticity) of the timepiece as a whole can be improved.
Further, in the above description, as one example of the timepiece, a wristwatch (portable timepiece) as a solar radio timepiece has been described, however, the invention can also be applied to other types of timepieces such as portable timepieces other than wristwatches, table clocks, and wall clocks in the same manner. Further, the invention can also be applied to any timepieces such as solar timepieces other than solar radio timepieces and radio timepieces other than solar radio timepieces.
Hereinabove, preferred embodiments of the invention have been described, however, the invention is not limited to those described above.
For example, in the optical component and the timepiece according to the invention, the configuration of each part can be replaced with an arbitrary configuration exhibiting a similar function, and also an arbitrary configuration can be added.
For example, the optical component may include a protective film or the like in addition to the base material and the antireflection film.
Further, the optical component according to the invention may include a plurality of antireflection films. For example, in the above-mentioned embodiment, a case where the antireflection film is provided on one surface side of the base material has been described, however, the antireflection film may be provided on both surface sides of the base material. Further, the optical component may have a configuration in which a plurality of antireflection films are stacked on one another through an intermediate layer.
Further, in the above-mentioned embodiment, a case where the optical component according to the invention is used as a constituent component of a timepiece has been mainly described, however, the optical component according to the invention is not limited to an optical component to be used as a constituent component of a timepiece, and may be an optical component to be applied to, for example, various electrical devices including optical devices such as cameras (including video cameras, cameras mounted on cellular phones (including smart phones, PHS, etc.), and the like) and projectors, optical measurement devices such as microscopes, and the like, and also to eyeglasses, loupes, and the like. Further, the optical component according to the invention is not limited to an optical component to be used in combination with another member, and may be an optical component to be used by itself alone.
Further, in the production of the optical component according to the invention, other than the above-mentioned steps, according to need, a pretreatment step, an intermediate treatment step, and a post-treatment step may be performed. For example, prior to the antireflection film forming composition application step, a step of performing UV irradiation, plasma irradiation, or the like on the surface of the base material may be included. According to this, for example, the wettability of the antireflection film forming composition on the base material can be made more favorable, and the antireflection film having a desired condition (for example, a desired film thickness) can be more favorably formed. Further, the adhesiveness between the base material and the antireflection film is made particularly excellent, and thus, the durability and reliability of the optical component can be made particularly excellent.
Further, the optical component according to the invention is not limited to those produced using the above-mentioned method. For example, in the above-mentioned embodiment, a case where the antireflection film is formed by using an antireflection film forming composition containing a dispersion medium in addition to silica particles has been described, however, for example, as the antireflection film forming composition, a composition containing no dispersion medium may be used.
EXAMPLES
Next, specific examples of the invention will be described.
1. Production of Optical Component (Cover Glass)
Example 1
By the method as described below, a cover glass as an optical component was produced.
First, a plate material (glass plate) composed of a sapphire glass was prepared as a base material (the base material preparation step), and a necessary part was cut and polished. The base material obtained by cutting and polishing had a substantially disk shape and had a size of 30 mm in diameter and 1 mm in thickness.
Subsequently, a UV irradiation treatment in which an ultraviolet ray with a wavelength of 248 nm was irradiated on the surface of the base material on the side where an antireflection film was going to be formed.
Subsequently, an antireflection film forming composition was applied onto the entire surface of one side of the base material by a spray coating method (antireflection film forming composition application step).
As the antireflection film forming composition, a composition obtained by mixing silica particles, tin oxide (SnO 2 ) particles (number-based average particle diameter: 2.0 nm) as conductive particles (conductive transparent metal oxide particles), and methanol as a dispersion medium at a given ratio was used.
As the silica particles, silica particles which have a first local maximum in the range of 1.5 nm or more and 2.5 nm or less (a first range), a second local maximum in the range of 3.5 nm or more and 4.5 nm or less (a second range), and a third local maximum in the range of 7.5 nm or more and 8.5 nm or less (a third range), and a fourth local maximum in the range of 5.5 nm or more and 6.5 nm or less (a fourth range) in a number-based particle size distribution, and also have a number-based average particle diameter of 2.6 nm were used.
Thereafter, the base material onto which the antireflection film forming composition was applied was left to stand in an environment at 1×10 −4 Pa to remove the dispersion medium constituting the antireflection film forming composition (dispersion medium removal step), whereby the antireflection film was formed.
The average thickness of the formed antireflection film was 80 nm and the porosity was 26% by volume. Further, the surface roughness Ra of the outer surface (the surface on an opposite side to the surface facing the base material) of the antireflection film was 1.3 nm.
Examples 2 to 10
Optical components (cover glasses) were produced in the same manner as in the above Example 1 except that the particle size distribution of the silica particles constituting the antireflection film forming composition was changed as shown in Table 1, and the configuration of the antireflection film forming composition and the configurations of the respective parts of the optical component were changed as shown in Table 2.
Example 11
An optical component (cover glass) was produced in the same manner as in the above Example 1 except that prior to the antireflection film forming composition application step, a foundation layer composed of SiO 2 was formed on the surface of the base material (the surface on the side where the antireflection film was going to be formed) (the foundation layer formation step).
The formation of the foundation layer was performed by vacuum vapor deposition. The thickness of the formed foundation layer was 15 nm.
Examples 12 to 14
Optical components (cover glasses) were produced in the same manner as in the above Example 11 except that the particle size distribution of the silica particles constituting the antireflection film forming composition was changed as shown in Table 1, and the configuration of the antireflection film forming composition and the configurations of the respective parts of the optical component were changed as shown in Table 2.
Comparative Example 1
An optical component (cover glass) was produced in the same manner as in the above Example 2 except that the base material (the plate material composed of a sapphire glass) was directly used as the optical component without forming an antireflection film on the base material.
Comparative Examples 2 to 4
Optical components (cover glasses) were produced in the same manner as in the above Example 2 except that the particle size distribution of the silica particles constituting the antireflection film forming composition was changed as shown in Table 1.
Comparative Example 5
An optical component (cover glass) was produced in the same manner as in the above Example 2 except that an anionic surfactant was used as the antireflection film forming composition and the antireflection film was formed as a film composed of a polymeric organic material.
The particle size distributions of the silica particles constituting the antireflection film forming compositions used in the production of the optical components (cover glasses) of the respective Examples and Comparative Examples are shown in Table 1, and the configurations of the antireflection film forming compositions used in the production of the optical components (cover glasses) of the respective Examples and Comparative Examples and the configurations of the respective parts of the optical components (cover glasses) of the respective Examples and Comparative Examples are shown in Table 2. Incidentally, in Tables 1 and 2, in the column of “average particle diameter”, the value of the number-based average particle diameter is shown. Further, in the above respective Examples and Comparative Examples, the particle size distribution of the particles was determined by laser diffractometry using a single nanoparticle size analyzer IG-1000 (manufactured by Shimadzu Corporation). Further, the viscosities (viscosities in the antireflection film forming composition application step) of the antireflection film forming compositions used in the above respective Examples and Comparative Examples as measured according to JIS Z 8809 using a vibration-type viscometer were all in the range of 3 mPa·s or more and 15 mPa·s or less.








TABLE 1




First range
Second range
Third range














Particle


Particle


Particle



Presence or
diameter of
Ratio of silica
Presence or
diameter of
Ratio of silica
Presence or
diameter of
Ratio of silica


absence of
first local
particles falling
absence of
second local
particles falling
absence of
third local
particles falling


first local
maximum
within first
second local
maximum
within second
third local
maximum
within third


maximum
(nm)
range (vol %)
maximum
(nm)
range (vol %)
maximum
(nm)
range (vol %)



Example 1
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 2
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 3
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 4
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 5
presence
2.0
20
presence
4.0
30
presence
8.0
50

Example 6
presence
2.0
30
presence
4.0
20
presence
8.0
50

Example 7
presence
2.0
20
presence
4.0
40
presence
8.0
40

Example 8
presence
2.0
20
presence
4.0
20
presence
8.0
60

Example 9
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 10
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 11
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 12
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 13
presence
2.0
15
presence
4.0
20
presence
8.0
40

Example 14
presence
2.0
15
presence
4.0
20
presence
8.0
40

Comparative
—
—
—
—
—
—
—
—
—

Example 1










Comparative
absence
—
—
presence
4.0
40
presence
8.0
60

Example 2










Comparative
presence
2.0
20
absence
—
—
presence
—
80

Example 3










Comparative
presence
2.0
40
presence
4.0
60
absence
—
—

Example 4










Comparative
—
—
—
—
—
—
—
—
—

Example 5










Fourth range











Presence or absence of
Particle diameter of
Ratio of silica particles falling
Average particle



fourth local maximum
fourth local maximum (nm)
within fourth range (vol %)
diameter (nm)




Example 1
presence
6.0
25
2.6


Example 2
presence
6.0
25
2.6


Example 3
presence
6.0
25
2.6


Example 4
presence
6.0
25
2.6


Example 5
absence
—
—
2.4


Example 6
absence
—
—
2.3


Example 7
absence
—
—
2.5


Example 8
absence
—
—
2.5


Example 9
presence
6.0
25
2.6


Example 10
presence
6.0
25
2.6


Example 11
presence
6.0
25
2.6


Example 12
presence
6.0
25
2.6


Example 13
presence
6.0
25
2.6


Example 14
presence
6.0
25
2.6


Comparative
—
—
—
—


Example 1






Comparative
absence
—
—
4.6


Example 2






Comparative
absence
—
—
2.4


Example 3






Comparative
absence
—
—
1.9


Example 4






Comparative
—
—
—
—


Example 5


























































































TABLE 2




Configuration of antireflection film forming composition









Silica


Configuration of optical component









particles
Conductive particles
Dispersion medium
Base material
Foundation layer













Content
Constituent
Average particle
Content
Constituent
Content
Constituent
Constituent
Thickness


(mass %)
material
diameter (nm)
(mass %)
material
(mass %)
material
material
(nm)



Example 1
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 2
2.0
—
—
—
methanol
98.0
Sapphire glass
—
—

Example 3
2.0
SnO 2
2.0
0.04
methanol
97.96
Sapphire glass
—
—

Example 4
2.0
SnO 2
2.0
0.5
methanol
97.5
Sapphire glass
—
—

Example 5
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 6
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 7
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 8
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 9
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 10
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
—
—

Example 11
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
SiO 2
15

Example 12
2.0
—
—
—
methanol
98.0
Sapphire glass
SiO 2
15

Example 13
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
SiO 2
5

Example 14
2.0
SnO 2
2.0
0.1
methanol
97.9
Sapphire glass
SiO 2
25

Comparative
—
—
—
—
—

Sapphire glass
—
—

Example 1










Comparative
2.0
—
—
—
methanol
98.0
Sapphire glass
—
—

Example 2










Comparative
2.0
—
—
—
methanol
98.0
Sapphire glass
—
—

Example 3










Comparative
2.0
—
—
—
methanol
98.0
Sapphire glass
—
—

Example 4










Comparative
—
—
—
—
—
—
Sapphire glass
—
—

Example 5


















Configuration of optical component



Antireflection film














Surface





Content
Thickness
roughness
Porosity



Constituent material
(vol %)
(nm)
Ra (nm)
(vol %)




Example 1
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.3
26


Example 2
SiO 2 particles
100
80
1.3
26


Example 3
SiO 2 particles/SnO 2 particles
99.7/0.3
80
1.3
26


Example 4
SiO 2 particles/SnO 2 particles
92.6/7.4
80
1.3
25


Example 5
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.2
23


Example 6
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.2
18


Example 7
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.3
24


Example 8
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.3
32


Example 9
SiO 2 particles/SnO 2 particles
98.4/1.6
50
1.3
26


Example 10
SiO 2 particles/SnO 2 particles
98.4/1.6
120
1.3
26


Example 11
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.2
26


Example 12
SiO 2 particles
100
80
1.2
26


Example 13
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.3
26


Example 14
SiO 2 particles/SnO 2 particles
98.4/1.6
80
1.1
26


Comparative
—
—
—
—
—


Example 1







Comparative
SiO 2 particles
100
80
2.3
38


Example 2







Comparative
SiO 2 particles
100
80
12
17


Example 3







Comparative
SiO 2 particles
100
80
1.0
15


Example 4







Comparative
Anionic surfactant
100
10
0.5
—


Example 5


























































































2. Evaluation of Reflectance
With respect to each of the cover glasses produced in the above respective Examples and Comparative Examples, the light reflectance from the cover glass was measured from the surface on the opposite side to the surface on which the antireflection film was provided of the base material using a reflectometer USPM manufactured by Olympus Corporation, and evaluation was performed according to the following criteria. Incidentally, in the case of Comparative Example 1, the antireflection film was not provided on both surfaces, and therefore, evaluation was performed for arbitrarily selected one surface (the same shall apply also to the following evaluation items).
A: The light reflectance is less than 0.3%.
B: The light reflectance is 0.3% or more and less than 0.5%.
C: The light reflectance is 0.5% or more and less than 1.0%.
D: The light reflectance is 1.0% or more and less than 4.0%.
E: The light reflectance is 4.0% or more.
3. Evaluation of Antifogging Property
The antifogging property evaluation index when saturated water vapor was sprayed onto the surface on the side where the antireflection film was provided of each of the cover glasses produced in the above respective Examples and Comparative Examples was obtained by using an antifogging property evaluation device (AFA-1 manufactured by Kyowa Interface Science Co., Ltd.), and evaluation was performed according to the following criteria. It can be said that as the antifogging property evaluation index is lower, the antifogging property is superior.
A: The antifogging property evaluation index is less than 3.
B: The antifogging property evaluation index is 3 or more and less than 6.
C: The antifogging property evaluation index is 6 or more and less than 10.
D: The antifogging property evaluation index is 10 or more and less than 20.
E: The antifogging property evaluation index is 20 or more.
4. Evaluation of Antistatic Property
A probe was brought into contact with the surface on the side where the antireflection film was provided of each of the cover glasses produced in the above respective Examples and Comparative Examples, and the surface electrical resistance was measured by using a surface resistance meter (Hiresta-UP MCP-HT45 manufactured by Mitsubishi Chemical Corporation), and evaluation was performed according to the following criteria. It can be said that as the surface electrical resistance is lower, the antistatic property is superior. The measurement was performed in an environment in which the temperature was 25° C. and the humidity was 55% RH.
A: The surface electrical resistance is less than 1E+8 Ω/□.
B: The surface electrical resistance is 1E+8 Ω/□ or more and less than 1E+9 Ω/□.
C: The surface electrical resistance is 1E+9 Ω/□ or more and less than 1E+11 Ω/□.
D: The surface electrical resistance is 1E+11 Ω/□ or more and less than 1E+15 Ω/□.
E: The surface electrical resistance is 1E+15 Ω/□ or more.
5. Evaluation of Adhesiveness
Five horizontal cut lines at 2 mm intervals and five vertical cut lines at 2 mm intervals were provided on the surface to be evaluated with a cutter, and an adhesive tape (CT-18 manufactured by Nichiban Co., Ltd.) was adhered thereto, and thereafter, the adhesive tape was peeled off at a stroke. Then, it was confirmed whether or not peeling occurred on the surface to be evaluated by visual observation, and evaluation was performed according to the following criteria.
A: No film peeling is observed.
B: The percentage of the area where film peeling occurred is less than 5%.
C: The percentage of the area where film peeling occurred is 5% or more and less than 20%.
D: The percentage of the area where film peeling occurred is 20% or more and less than 50%.
E: The percentage of the area where film peeling occurred is 50% or more.
6. Evaluation of Abrasion Resistance
An abrasion resistance test using silbon paper as a counter paper was performed according to JIS K 5701 for the surface on the side where the antireflection film was provided of each of the cover glasses produced in the above respective Examples and Comparative Examples. Then, the cover glass after the abrasion resistance test was visually observed, and evaluation was performed according to the following criteria.
A: No scratches by rubbing occur.
B: Almost no scratches by rubbing occur.
C: Scratches by rubbing slightly occur.
D: Scratches by rubbing clearly occur.
E: Scratches by rubbing remarkably occur.
7. Production of Timepiece
By using each of the cover glasses produced in the above respective Examples and Comparative Examples, wristwatches as shown in FIG. 4 were produced. At this time, the surface on the side where the antireflection film was provided of the cover glass was disposed facing the inner surface side (a side facing the dial plate and the like).
8. Evaluation of Visibility of Dial Plate of Timepiece
With respect to each of the timepieces produced in the above respective Examples and Comparative Examples, the dial plate and the like were observed through the cover glass, and the visibility at that time was evaluated according to the following criteria.
A: The visibility of the dial plate and the like is very high.
B: The visibility of the dial plate and the like is high.
C: The visibility of the dial plate and the like is within the acceptable range.
D: The visibility of the dial plate and the like is somewhat low.
E: The visibility of the dial plate and the like is very low.
These results are shown in Table 3.











TABLE 3





Antifogging
Antistatic

Abrasion
Visibility of


Reflectance
property
property
Adhesiveness
resistance
dial plate



Example 1
A
A
A
B
A
A

Example 2
A
A
D
B
A
A

Example 3
A
A
C
B
A
A

Example 4
B
A
A
B
A
B

Example 5
A
B
A
B
A
A

Example 6
B
C
A
B
A
B

Example 7
A
B
A
B
B
A

Example 8
A
C
A
C
B
A

Example 9
B
B
A
B
A
B

Example 10
B
A
A
B
A
B

Example 11
A
A
A
A
A
A

Example 12
A
A
D
A
A
A

Example 13
A
A
A
B
A
A

Example 14
B
A
A
A
A
B

Comparative
E
E
E
—
A
E

Example 1







Comparative
C
C
D
C
B
C

Example 2







Comparative
C
B
D
B
A
C

Example 3







Comparative
C
C
D
B
A
C

Example 4







Comparative
E
A
E
D
D
E

Example 5









































As apparent from Table 3, according to the invention, the optical component had a high antireflection function and also had excellent antifogging property and abrasion resistance. In particular, an excellent effect as described above was obtained with a simple structure. Further, the timepieces including the optical component had high visibility of the dial plate and the like, and the aesthetic appearance (aestheticity) of the timepiece as a whole was excellent. In addition, according to the invention, the optical component could be produced with high productivity. On the other hand, in the case of Comparative Examples, satisfactory results were not obtained.
When timepieces were produced in the same manner as in the above respective Examples and Comparative Examples except that in addition to the cover glass, also the rear lid was configured in the same manner as described above, the same results as described above were obtained, and in the timepieces to which the optical component according to the invention was applied (timepieces according to the invention), the aesthetic appearance (aestheticity) could be made particularly excellent.
When cover glasses (optical components) and timepieces were produced in the same manner as described above except that the application of the antireflection film forming composition was performed by a roll coating method or a spin coating method and the evaluation was performed in the same manner as described above, the same results as described above were obtained.
The entire disclosure of Japanese Patent Application No. 2014-244845, filed Dec. 3, 2014 is expressly incorporated by reference herein.