By a News Reporter-Staff News Editor at Nanotechnology Weekly -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Yabuta, Takeshi (Tokyo, JP); Kondo, Fumiyoshi (Tokyo, JP); Kawazu, Mitsuhiro (Tokyo, JP), filed on February 1, 2013, was published online on November 8, 2016.
The assignee for this patent, patent number 9486779, is NIPPON SHEET GLASS COMPANY, LIMITED (Tokyo, JP).
Reporters obtained the following quote from the background information supplied by the inventors: "Glass sheets utilizing the photocatalytic function exerted by titanium oxide films are manufactured and commercially sold as so-called 'self-cleaning glass'. As is well known, the photocatalytic function of titanium oxide films causes decomposition of organic substances adhered to the surfaces of glass sheets and thereby weakening of the adhesiveness of the organic substances, thus allowing the organic substances to be washed away by rainwater or the like.
"The refractive index of titanium oxide (about 2.5 in the case of the anatase type) is higher than the refractive index of glass. For this reason, the formation of a titanium oxide film on a surface of a glass sheet increases the light reflectance of the glass sheet. Therefore, in view of uses for which increase in light reflectance is not desired (e.g., uses in solar cells or greenhouses), a photocatalyst film capable of suppressing the increase in light reflectance has been proposed. In this photocatalyst film, the refractive index of the film is decreased by having the film contain not only titanium oxide particles but also particles of silicon oxide having a lower refractive index than titanium oxide. A sufficient decrease in the refractive index of the photocatalyst film allows a decrease in reflectance of light incident on the glass sheet.
"WO 2011/021383 A1 (Patent Literature 1) discloses a glass article including a glass sheet and a photocatalyst film formed on a surface of the glass sheet, the glass article being an improved glass article made suitable for long-term use by enhancing the film strength of the photocatalyst film while maintaining the photocatalytic function and the reflection-reducing function of the photocatalyst film.
"As shown in FIG. 11, in a photocatalyst film 11 disclosed in Patent Literature 1, some silicon oxide particles denoted by 17 are situated in the uppermost portion of the film and are connected to a glass sheet 12 via silicon oxide particles 16 situated in the lower portion. The silicon oxide particles 16 and 17 and the glass sheet 12 are firmly fixed together by a binder material. Titanium oxide particles 15 are situated lower than the top portions of the silicon oxide particles 17. Such a film structure is suitable for increasing the film strength and for maintaining the function of the photocatalyst film by preventing detachment of titanium oxide."
In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "Technical Problem
"The photocatalyst film disclosed in Patent Literature 1 increases the transmittance of incident light by its reflection-reducing function. However, the amount of the increase as expressed by an average transmittance over the wavelength region from 400 to 1200 nm is only less than 2.0% (Examples shown in Tables 1 and 2 of Patent Literature 1). There is still room for improvement.
"The present invention is directed to a glass article including a photocatalyst film containing silicon oxide particles and titanium oxide particles, and aims to further increase the transmittance by improvement of the reflection-reducing function while maintaining the film strength of the photocatalyst film and the photocatalytic function exerted by the titanium oxide particles.
"Solution to Problem
"The present invention provides a glass article including a glass sheet and a photocatalyst film formed on a surface of the glass sheet. The photocatalyst film contains silicon oxide particles, titanium oxide particles, and a binder material whose main component is silicon oxide. The silicon oxide particles are contained in an amount of 72 to 79 mass %, the titanium oxide particles are contained in an amount of 13 to 18 mass %, and the binder material is contained in an amount of 8 to 14 mass %, with respect to a total amount of the silicon oxide particles, the titanium oxide particles, and the binder material. The silicon oxide particles have an average particle diameter of 30 nm to 200 nm, the titanium oxide particles have an average particle diameter of 5 nm to 20 nm, and the average particle diameter of the silicon oxide particles is five times or more of the average particle diameter of the titanium oxide particles. Assuming that the photocatalyst film has a film thickness T, 80% or more of the titanium oxide particles are present between the surface of the glass sheet and a position spaced from the surface by 0.6 T toward a surface of the photocatalyst film in a thickness direction of the photocatalyst film.
"Advantageous Effects of Invention
"According to the present invention, in a glass article including a photocatalyst film containing silicon oxide particles and titanium oxide particles, a further increase in transmittance can be achieved while maintaining the film strength of the photocatalyst film and the photocatalytic function exerted by the titanium oxide particles."
For more information, see this patent: Yabuta, Takeshi; Kondo, Fumiyoshi; Kawazu, Mitsuhiro. Glass Article Provided with Photocatalyst Film. U.S. Patent Number 9486779, filed February 1, 2013, and published online on November 8, 2016. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9486779.PN.&OS=PN/9486779RS=PN/9486779
Keywords for this news article include: Silicon, Titanium, Light Metals, Photocatalyst, Nanotechnology, Photocatalytic, Emerging Technologies, NIPPON SHEET GLASS COMPANY LIMITED.
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