JP2011093763A - Glass ceramic and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalytic functional material having excellent photocatalytic activity as well as excellent durability. <P>SOLUTION: Provided is glass ceramics containing a crystal phase including crystals of niobium oxide, crystals of niobate and/or solid solutions of those. The glass ceramics may contain, on a basis of mol%, an Nb<SB>2</SB>O<SB>5</SB>component by 5 to 50% with respect to the amount of the whole substances of the composition in terms of oxides, and further may contain an Rn<SB>2</SB>O and/or RO component by 5 to 40% (wherein Rn represents at least one element selected from Li, Na and K, and R represents at least one element selected from Mg, Ca, Sr, Ba and Zn). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a glass ceramic containing a crystal phase containing a niobium component and having photocatalytic activity, and a method for producing the same.

  Photocatalysts that cause a surface chemical reaction using light energy have been attracting attention in various fields in recent years because they have been found to generate energy using sunlight, purify pollutants, and the like. A substance having photocatalytic activity (hereinafter sometimes simply referred to as “photocatalyst”) generates electrons and holes when irradiated with light having energy higher than the band gap energy. In the vicinity, the redox reaction is strongly promoted. Further, it is known that the surface of a molded body containing a photocatalyst has a so-called self-cleaning action in which it is washed with water droplets such as rain because it exhibits hydrophilicity that easily wets water.

  As a photocatalyst, titanium oxide has been mainly studied. However, since titanium oxide has a band gap of 3 to 3.2 eV, it is necessary to irradiate ultraviolet rays with a wavelength of 400 nm or less, and visible light has sufficient photocatalytic activity. There is a disadvantage that it cannot be obtained. In addition, pure titanium oxide is a white powder that has almost no substance-adsorbing ability and is not sufficiently photocatalytic. Therefore, extensive research has been conducted to enhance photocatalytic activity by controlling the band structure such as dope and solid solution. ing. On the other hand, research for finding new photocatalysts has been actively conducted, and niobium oxide has attracted attention as one of them. For example, potassium niobate is attracting attention as a photodecomposition catalyst for water that generates charge separation by light irradiation and converts light energy into chemical energy. Patent Document 1 discloses a small particle size as a photocatalyst used for water decomposition. A method of producing a potassium niobate photocatalyst having a large specific surface area, preferably a potassium niobate photocatalyst supported with nickel oxide as a cocatalyst, is disclosed.

On the other hand, niobium oxide and niobium composite oxide are known as high dielectric constant materials and have long been used as capacitor electrodes, piezoelectric elements, light modulation elements, and the like. For example, Patent Document 2 discloses a two-layer capacitor mainly composed of niobium oxide obtained by thermally decomposing a complex containing niobium, and Patent Document 3 discloses a single crystal thin film substrate of LiNbO _3. A piezoelectric element having electrodes formed thereon is disclosed. Patent Document 4 discloses a high-dielectric material for optical elements, in which a glass containing a niobium component is heat-treated to precipitate a niobium composite salt crystal.

JP 2003-126695 A JP 2000-188243 A Japanese Patent Laid-Open No. 03-190292 US Patent 3,140,066

  While various substances have been found as novel photocatalysts, many conventional techniques related to photocatalysts adopt the concept of supporting a photocatalyst by forming a film containing the photocatalyst on the surface of a substrate. However, a problem common to techniques based on such a concept is that it is difficult to ensure the adhesion between the substrate and the film containing the photocatalyst and the durability of the film itself. That is, in the photocatalytic functional product manufactured by these methods, the film containing the photocatalyst may be peeled off from the base material, or the film may deteriorate and the photocatalytic function may be impaired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photocatalytic functional material having excellent photocatalytic activity and excellent durability.

  As a result of intensive studies to solve the above problems, the present inventors have found that a crystal phase containing a niobium component in a glass, typically a crystal of niobium oxide, a crystal of niobate and / or a solid solution thereof. As a result, the inventors have found that the glass ceramic itself can be used as a photocatalyst by producing a crystal phase containing, and that a material and product having an excellent photocatalytic function can be provided from the glass ceramic, thereby completing the present invention. That is, this invention exists in the following (1)-(29).

(1) Glass ceramics containing a crystal phase containing a niobium component and having photocatalytic activity.

(2) the total amount of substance of the oxide composition in terms of, in mol%, the glass ceramics according to _Nb 2 _{O 5} component to the above (1) containing 5-50%.

(3) The crystal phase is RnNbO ₃ crystal, RNb ₂ O ₆ crystal (Rn is one or more selected from Li, Na, and K, and R is selected from Mg, Ca, Sr, Ba, and Zn) Glass ceramics according to (1) or (2) above, comprising one or more crystals selected from the group consisting of these solid solutions.

(4) One or more components 30 to 75 selected from the group consisting of a SiO ₂ component, a B ₂ O ₃ component, and a P ₂ O ₅ component in mol% with respect to the total amount of the oxide-converted composition. % Of the glass ceramic according to any one of (1) to (3).

(5) The above (4) containing 5 to 40% of Rn ₂ O and / or RO component (Rn and R have the same meaning as described above) in mol% with respect to the total amount of the oxide-converted composition. Glass ceramics described in 1.

(6) the total amount of substance of the oxide composition in terms of molar percent, the glass ceramics according to the above (5), further containing 0 to 35% _Ta 2 _{O 5} component.

(7) relative to the total material of the oxide composition in terms of molar percent, the glass ceramics according to the above (6) which further contains 0 to 20% TiO ₂ component and / or ZrO ₂ component.

(8) relative to the total material of the oxide composition in terms of, in mol%, the glass ceramics according to the above (7), further containing 0 to 30% _Al 2 _{O 3} component.

(9) The Nb ₂ O ₅ and / or Ta ₂ O _{5 with} respect to the total amount of the Rn ₂ O and / or RO components (Rn and R have the same meaning as described above) in a molar ratio of the oxide equivalent composition, And the ratio of the total amount of one or more components selected from the group consisting of TiO ₂ , ZrO ₂ and Al ₂ O ₃ [(Nb ₂ O ₅ + Ta ₂ O ₅ + TiO ₂ + ZrO ₂ + Al ₂ O ₃ ) / (Rn ₂ O + RO)] is larger than 1. The glass ceramic according to (8).

(10) In mol% with respect to the total amount of substances in oxide equivalent composition,
GeO ₂ component 0-20% and / or Ga ₂ O ₃ component 0-20% and / or In ₂ O ₃ component 0-10% and / or SnO component 0-10% and / or Bi ₂ O ₃ components 0-20% and / or TeO ₂ components 0-20% and / or WO ₃ components 0-20% and / or MoO ₃ components 0-20% and / or As ₂ O ₃ components and / or Or Sb ₂ O ₃ component Total 0-5%
The glass ceramic according to any one of (1) to (9), further comprising each component of

(11) Ln ₂ O ₃ component (where Ln is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, One of at least one selected from the group consisting of Tb, Dy, Ho, Er, Tm, Yb, and Lu). The glass ceramic described.

(12) M _x O _y component (where M is one selected from the group consisting of V, Cr, Mn, Fe, Co, and Ni, in mol% with respect to the total amount of oxide-converted composition) Any one of (1) to (11) above, wherein x and y are the smallest natural numbers satisfying x: y = 2: M valence, respectively) Glass ceramics according to crab.

(13) The composition according to any one of (1) to (12), wherein at least one component selected from the group consisting of F, Cl, and Br is contained in an outer divided mass ratio of 15% or less with respect to the total mass of the glass. Glass ceramics.

(14) Any one of (1) to (13) above containing at least one component selected from the group consisting of Cu, Ag, Au, Pd, and Pt in an externally divided mass ratio of 5% or less with respect to the total mass of the glass Glass ceramics according to crab.

(15) The glass ceramic according to any one of (1) to (14), wherein the contact angle between the surface irradiated with light having a wavelength from the ultraviolet region to the visible region and a water droplet is 30 ° or less.

(16) The glass ceramic according to any one of (1) to (15), wherein the decomposition activity index of methylene blue based on JIS R 1703-2: 2007 is 3.0 nmol / L / min or more.

(17) The glass ceramic according to any one of (1) to (16), wherein an average crystal grain size when approximated to a sphere is 200 nm or less.

(18) A photocatalytic functional glass ceramic molded body comprising the glass ceramic according to any one of (1) to (17).

(19) A hydrophilic glass-ceramic shaped article comprising the glass-ceramic according to any one of (1) to (17).

(20) A photocatalyst comprising the glass ceramic according to any one of (1) to (17).

(21) The photocatalyst according to (20) having the fiber or bead shape.

(22) A photocatalytic material comprising the photocatalyst according to any one of (20) and (21).

(23) A photocatalyst member comprising the photocatalyst according to any one of (20) and (21).

(24) A hydrophilic material containing the photocatalyst according to any one of (20) and (21).

(25) A hydrophilic member containing the photocatalyst according to any one of (20) and (21).

(26) A paint, purification device, or filter containing the photocatalyst according to any of (20) or (21).

(27) The glass ceramic manufacturing method according to any one of (1) to (17),
A melting step of mixing raw materials to obtain a melt;
A cooling step of cooling the melt to obtain glass;
A reheating step of raising the temperature of the glass to a crystallization temperature region;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A re-cooling step of obtaining a crystal-dispersed glass by lowering the temperature outside the crystallization temperature region.

(28) The method for producing glass ceramics according to (27), wherein the crystallization temperature region is 450 ° C. or higher and 1200 ° C. or lower.

(29) The glass ceramic manufacturing method according to any one of (27) to (28), further including an etching step of performing dry etching and / or wet etching on the glass ceramic.

  The glass ceramic of the present invention has an excellent photocatalytic activity because a crystal phase containing a niobium component having a photocatalytic activity is uniformly present inside and on the surface thereof. Further, even if the surface is scraped, there is little deterioration in performance, and it is extremely excellent in durability. Moreover, the glass ceramics of the present invention have a high degree of freedom when processing the size and shape, and can be used for various articles that require a photocatalytic function. Thus, the glass ceramics of the present invention can be used for various applications as a photocatalyst.

  Further, according to the method for producing glass ceramics of the present invention, it is possible to generate a crystal phase containing a niobium component in the glass by controlling the composition of the raw materials and the heat treatment temperature, which is excellent without using special equipment. It is possible to easily produce glass ceramics having a photocatalytic activity and useful as a photocatalytic functional material on an industrial scale.

It is an XRD pattern about the glass ceramic of Example 1 of this invention. It is an XRD pattern about the glass ceramic of Example 2 of this invention. It is an XRD pattern about the glass ceramic of Example 12 of this invention. It is the graph which plotted the contact angle with water with respect to ultraviolet irradiation time about the glass-ceramics of Example 1 of this invention. It is the graph which plotted the contact angle with water with respect to ultraviolet irradiation time about the glass-ceramics of Example 2 of this invention. It is the graph which plotted the contact angle with water with respect to ultraviolet irradiation time about the glass-ceramic of Example 12 of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
[Glass ceramics]
The glass ceramic of the present invention contains crystals containing a niobium component. Glass ceramics is a material obtained by precipitating a crystalline phase in a glass phase by heat-treating the glass, and is also called crystallized glass. Since the glass ceramic of the present invention contains a crystal phase containing a niobium component, it has a strong photocatalytic activity and can be used as it is as a photocatalyst. Thus, the use of glass ceramics having a crystal phase of a niobium component as a photocatalyst has been realized for the first time by the present invention. The glass ceramic of the present invention includes not only a material composed of a glass phase and a crystal phase, but also a material in which the glass phase is entirely changed to a crystal phase, that is, a material whose crystal amount (crystallinity) in the material is 100% by mass. It's okay. The glass ceramics of the present invention can control the crystal grain size, the type of precipitated crystals, and the crystallinity by controlling the crystallization process.

  Next, components and physical properties of the glass ceramic of the present invention will be described. In addition, in this specification, unless there is particular notice, content of each component which comprises glass ceramics shall be displayed by the mol% with respect to the total amount of glass ceramics of an oxide conversion composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. It is the composition which described each component contained in glass by making the total substance amount of the said production | generation oxide into 100 mol%.

A crystal containing a niobium component, for example, a crystal of niobium oxide, a crystal of niobate and / or a solid solution thereof is an essential component that provides photocatalytic properties to glass ceramics. Niobium oxide becomes a divalent to pentavalent oxide depending on the raw material and the preparation method, and its crystal is known as NbO crystal, Nb ₂ O ₃ crystal, NbO ₂ crystal, Nb ₂ O ₅ crystal, etc. Nb ₂ O ₅ crystals having a valent oxidation number are most stable and preferred. Niobate is considered to be a composite oxide of Nb ₂ O ₅ and oxides of other elements, and the crystals thereof include, for example, lithium niobate (LiNbO ₃ ) crystals, sodium niobate (NaNbO ₃ ) crystals, niobium Potassium oxide (KNbO ₃ ) crystal, calcium niobate (CaNb ₂ O ₆ ) crystal, strontium niobate (SrNb ₂ O ₆ ) crystal, barium niobate (BaNb ₂ O ₆ ) crystal, magnesium niobate (MgNb ₂ O ₆ ) Crystal, strontium diniobate (Sr ₂ Nb ₂ O ₇ ) crystal, potassium strontium diniobate (K ₂ SrNb ₂ O ₇ ) crystal and the like, but not limited thereto. In the glass ceramics of the present invention, the type of niobium oxide crystal and / or niobate crystal is not limited as long as it has photocatalytic activity, but RnNbO ₃ (Rn is composed of Li, Na, and K) having particularly strong photocatalytic activity. It is preferable to include crystals that are one or more selected from the group. One typical niobate salt, potassium niobate (KNbO ₃ ), has a perovskite structure, and is known to be rhombohedral, orthorhombic, tetragonal, and cubic depending on temperature. However, any crystal lattice may be used as long as it has photocatalytic activity.

The crystals of niobate may exist in the form of a solid solution with other elements. Here, as the solid solution, for example, _{Rn (Ta q Nb 1-q} ) O 3, Rn α R β (Ta q Nb 1-q) γ O δ ( wherein, Rn and R have the same meanings as defined above Q is a stoichiometric number, and is a relational expression of α + 2β + 5γ = 2δ, where γ is an integer greater than 1. The solid solution may be a substitutional solid solution or an interstitial solid solution.

The glass ceramic of the present invention preferably contains the Nb ₂ O ₅ component in a range of 5 to 50% by mol% with respect to the total amount of the oxide-converted composition. If the content of the Nb ₂ O ₅ component is less than 5%, sufficient photocatalytic activity cannot be obtained. On the other hand, if the content of the Nb ₂ O ₅ component exceeds 50%, the stability of the glass is impaired. Therefore, the content of the Nb ₂ O ₅ component with respect to the total amount of the oxide-converted composition is preferably 5%, more preferably 10%, most preferably 15%, and preferably 50%, more preferably 40%. %, Most preferably 35%. The Nb ₂ O ₅ component can be introduced into the glass ceramic using, for example, Nb ₂ O ₅ as a raw material.

The SiO ₂ component is a component that constitutes the glass network structure and improves the stability and chemical durability of the glass, and is present in the vicinity of the crystal phase containing the niobium component on which Si ⁴⁺ ions are precipitated, and has photocatalytic activity. It is a component that contributes to improvement, and can be optionally added. However, when the content of the SiO ₂ component exceeds 75%, the meltability of the glass is deteriorated, and the crystal phase containing the niobium component is hardly precipitated. Therefore, when the SiO ₂ component is added, the content of the SiO ₂ component is preferably 30%, more preferably 40%, and most preferably 50%, preferably 75% with respect to the total amount of the oxide-converted composition. %, More preferably 70%, and most preferably 65%. SiO ₂ component may be incorporated in the glass ceramic is used as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The B ₂ O ₃ component is a component that constitutes a glass network structure and improves the stability of the glass, and can be optionally added. However, if the content exceeds 75%, the chemical durability of the glass is lowered, and the tendency that the crystal phase containing the niobium component is difficult to precipitate becomes strong. _Accordingly, when adding B 2 _{O 3} component, the content of _B 2 _{O 3} component to all substances of the oxide composition in terms is to preferably 30%, more preferably 35%, and most preferably the lower limit of 40% The upper limit is preferably 75%, more preferably 65%, and most preferably 55%. B ₂ O ₃ component may be incorporated in the glass ceramics used as the material for example _{H 3 BO 3, Na 2 B} 4 O 7, Na 2 B 4 O 7 · 10H 2 O, the BPO ₄ and the like.

P ₂ O ₅ component is a component which constitutes the network structure of the glass is a component that can be added optionally. By making the glass ceramic of the present invention a phosphate glass in which the P ₂ O ₅ component is the main component of the network structure, more niobium components can be incorporated into the glass. Further, by blending the P ₂ O ₅ component, it is possible to precipitate crystals containing niobium components at a lower heat treatment temperature. However, when the content of P ₂ O ₅ exceeds 75%, a crystal phase containing a niobium component is difficult to precipitate. _Therefore, when adding P 2 _{O 5} component, the content of _P 2 _{O 5} component to all substances of the oxide composition in terms is to preferably 30%, more preferably the lower limit of 35%, preferably 75%, The upper limit is more preferably 65%, and most preferably 55%. The P ₂ O ₅ component is introduced into the glass ceramic using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , NaPO ₃ , BPO ₄ , H ₃ PO _4, etc. as raw materials. can do.

The glass ceramic of the present invention preferably contains at least one component selected from an SiO ₂ component, a B ₂ O ₃ component, and a P ₂ O ₅ component within a range of 30% to 75%. In particular, by making the total amount of the SiO ₂ component, the B ₂ O ₃ component, and the P ₂ O ₅ component 75% or less, the meltability, stability, and chemical durability of the glass are improved, and the target crystalline phase Is more likely to precipitate. Therefore, the total amount (SiO ₂ + B ₂ O ₃ + P ₂ O ₅ ) with respect to the total amount of the oxide-converted composition is preferably 75%, more preferably 70%, and most preferably 65%. If the total amount of these components is less than 30%, it becomes difficult to obtain glass, so addition of 30% or more is preferable, 35% or more is more preferable, and 40% or more is most preferable. Further, among the SiO ₂ component, the B ₂ O ₃ component, and the P ₂ O ₅ component, the SiO ₂ component is used because it is easy to improve the stability and durability of the glass and to easily precipitate the target crystal phase. Most preferably, by containing at least 50% or more of the SiO ₂ component, glass which is a glass ceramic precursor can be stably produced, and glass ceramic having high durability and photocatalytic properties can be obtained.

The Li ₂ O component is a component that generates lithium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, when the content of the Li ₂ O component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the content of the Li ₂ O component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. Li ₂ O component may be incorporated in the glass ceramic by using, for example, _Li 2 _CO 3 as a raw material, LiNO _3, LiF and the like.

The Na ₂ O component is a component that generates sodium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, if the content of the Na ₂ O component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the content of the Na ₂ O component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. Na ₂ O component may be incorporated in the glass ceramic is used as a raw material for example _{Na 2 O, Na 2 CO 3} , NaNO 3, NaF, Na 2 S, the Na 2 SiF ₆ or the like.

The K ₂ O component is a component that generates potassium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, if the content of the K ₂ O component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the content of the K ₂ O component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. K ₂ O component may be incorporated in the glass ceramic by using the raw material as for example _{K 2 CO 3, KNO 3,} KF, KHF 2, K 2 SiF 6 and the like.

The glass ceramic of the present invention contains 40% or less of at least one component selected from Rn ₂ O (wherein Rn is one or more selected from the group consisting of Li, Na, and K). Is preferred. In particular, when the total amount of the Rn ₂ O component is 40% or less, the stability of the glass is improved and the crystal phase containing the niobium component is likely to precipitate, so that the catalytic activity of the glass ceramic can be ensured. . Therefore, the total amount of the Rn ₂ O component is preferably 40%, more preferably 30%, and most preferably 25% with respect to the total amount of substances in oxide equivalent composition.

The MgO component is a component that generates magnesium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, if the content of the MgO component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the content of the MgO component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 20%. The MgO component can be introduced into the glass ceramic using, for example, MgCO ₃ or MgF ₂ as a raw material.

The CaO component is a component that generates calcium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, when the content of the CaO component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Accordingly, the content of the CaO component with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. The CaO component can be introduced into the glass ceramic using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component that generates strontium niobate crystals having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, when the content of the SrO component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the SrO component content is preferably 40%, more preferably 30%, and most preferably 25% with respect to the total amount of substances in oxide equivalent composition. The SrO component can be introduced into the glass ceramic using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

The BaO component is a component that generates a barium niobate crystal having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, if the content of the BaO component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the content of the BaO component with respect to the total amount of oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. The BaO component can be introduced into the glass ceramic using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like as a raw material.

The ZnO component is a component that generates a zinc niobate crystal having photocatalytic activity with the Nb ₂ O ₅ component and improves the meltability and stability of the glass, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, when the content of the ZnO component exceeds 40%, the stability of the glass is deteriorated, and the precipitation of the crystal phase containing the niobium component becomes difficult. Therefore, the upper limit of the ZnO component content is preferably 40%, more preferably 30%, and most preferably 25% with respect to the total amount of substances in oxide equivalent composition. The ZnO component can be introduced into the crystallized glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

  The glass ceramic of the present invention contains 40% or less of at least one component selected from RO (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn). It is preferable. In particular, when the total amount of the RO component is 40% or less, the stability of the glass is improved, and the crystal phase containing the niobium component is easily precipitated, so that the catalytic activity of the glass ceramic can be ensured. Therefore, the total amount of the RO component is preferably 40%, more preferably 30%, and most preferably 25% with respect to the total amount of the oxide-converted composition.

Further, the glass ceramic of the present invention comprises an RO (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) and Rn ₂ O (where Rn is Li, Na And at least one component selected from the group consisting of one or more selected from the group consisting of K and 40% or less. In particular, when the total amount of the RO component and the Rn ₂ O component is 40% or less, the stability of the glass is improved, the glass transition temperature (Tg) is lowered, and the glass ceramic having the target crystal phase is more easily obtained. can get. On the other hand, when the total amount of the RO component and the Rn ₂ O component is more than 40%, the stability of the glass is deteriorated and it is difficult to precipitate a crystal phase containing the niobium component. Accordingly, the total amount (RO + Rn ₂ O) with respect to the total amount of the oxide-converted composition is preferably 40%, more preferably 30%, and most preferably 25%. Further, among the RO component and the Rn ₂ O component, it is most preferable to use a Na ₂ O component particularly in order to obtain high photocatalytic properties. Therefore, higher photocatalytic properties can be obtained by containing at least 0.5% Na ₂ O component in the glass ceramic.

Here, the glass ceramic of the present invention has an RO (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) component and Rn ₂ O (wherein Rn is Li, By containing two or more components selected from the group consisting of Na and K (one or more selected from the group consisting of Na and K), the stability and chemical durability of the glass are greatly improved. The mechanical strength becomes higher, and the crystal phase containing the niobium component is more likely to precipitate from the glass. Thus, glass-ceramics of the present invention preferably contain two or more of the components selected from the RO component and Rn 2 _O components.

The Ta ₂ O ₅ component is a component that improves the stability of the glass and is a component that improves the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or in the vicinity thereof, and is optionally added. It is a possible ingredient. However, when the content of the Ta ₂ O ₅ component exceeds 35%, the stability of the glass is remarkably deteriorated. Therefore, the content of the Ta ₂ O ₅ component with respect to the total amount of the oxide-converted composition is preferably 35%, more preferably 30%, and most preferably 25%. The Ta ₂ O ₅ component can be introduced into glass ceramics using, for example, Ta ₂ O ₅ as a raw material.

TiO ₂ component is glass meltability, a component for improving the stability and chemical durability, which is a component that can be added optionally. The TiO ₂ component also has the effect of acting as a nucleating agent for the crystal phase containing the niobium component, and thus contributes to the precipitation of the crystal phase containing the niobium component. However, when the content of the TiO ₂ component exceeds 20%, vitrification becomes difficult, and precipitation of a crystal phase other than the target becomes remarkable. Therefore, when the TiO ₂ component is added, the content of the TiO ₂ component is preferably 20%, more preferably 15%, and most preferably 10% with respect to the total amount of the oxide-converted composition. TiO ₂ component may be incorporated in the glass ceramics used as the starting material for example TiO ₂ or the like.

ZrO ₂ component is a component that enhances the chemical durability of glass ceramics, promotes precipitation of crystals containing niobium component, and contributes to improvement of photocatalytic properties by solid solution of Zr ⁴⁺ ions in the crystal phase containing niobium component It is a component that can be optionally added. However, when the content of the ZrO ₂ component exceeds 20%, vitrification becomes difficult. Therefore, the upper limit of the content of the ZrO ₂ component with respect to the total amount of the oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. The ZrO ₂ component can be introduced into glass ceramics using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

The glass ceramic of the present invention preferably contains 20% or less of a TiO ₂ component and / or a ZrO ₂ component. In particular, when the total amount of these components is 20% or less, the stability of the glass ceramic is ensured, so that a good glass ceramic can be formed. Therefore, the total amount (TiO ₂ + ZrO ₂ ) with respect to the total amount of the oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. In addition, although it is possible to obtain glass ceramics having high photocatalytic properties even if neither TiO ₂ component nor ZrO ₂ component is contained, by making the total amount of these components 0.1% or more, The photocatalytic properties of the glass ceramic can be further improved. Accordingly, the total amount (TiO ₂ + ZrO ₂ ) with respect to the total amount of the oxide-converted composition is preferably 0.1%, more preferably 0.5%, still more preferably 1%, and most preferably 2%. To do.

The Al ₂ O ₃ component enhances the stability of the glass and the chemical durability of the glass ceramic, promotes the precipitation of the crystal phase containing the niobium component from the glass, and Al ³⁺ ions solidify into the crystal phase containing the niobium component. It is a component that dissolves and contributes to the improvement of photocatalytic properties, and can be optionally added. However, when the content exceeds 30%, the melting temperature is remarkably increased and vitrification becomes difficult. Therefore, when the Al ₂ O ₃ component is added, the content of the Al ₂ O ₃ component is preferably 0.1%, more preferably 0.5%, most preferably 1 with respect to the total amount of the oxide-converted composition. % Is the lower limit, preferably 30%, more preferably 20%, and most preferably 10%. The Al ₂ O ₃ component can be introduced into the glass ceramic using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The glass ceramic of the present invention has a molar ratio of the oxide equivalent composition, and the Nb ₂ O ₅ and / or Ta with respect to the total amount of the Rn ₂ O and / or RO components (Rn and R have the same meaning as described above). Ratio of the total amount of one or more components selected from the group consisting of ₂ O ₅ and TiO ₂ , ZrO ₂ and Al ₂ O ₃ [(Nb ₂ O ₅ + Ta ₂ O ₅ + TiO ₂ + ZrO ₂ + Al ₂ O ₃ ) / (Rn ₂ O + RO)] is preferably greater than 1 (Rn and R have the same meaning as above). By making the ratio of the total amount of these components larger than 1, the crystal phase containing the niobium component is more likely to precipitate, which can contribute to further improvement of the photocatalytic properties of the glass ceramic. In order to further improve the photocatalytic properties, the ratio of the above total amount [(Nb ₂ O ₅ + Ta ₂ O ₅ + TiO ₂ + ZrO ₂ + Al ₂ O ₃ ) / (Rn ₂ O + RO)] (Rn and R are (Having the same meaning as above) is preferably 3 or less, more preferably in the range of 1.1 to 2, more preferably in the range of 1.1 to 1.7, and in the range of 1.1 to 1.5. Most preferred. In addition, although it is possible to obtain glass ceramics having high photocatalytic properties even when none of the TiO ₂ component, the ZrO ₂ component, and the Al ₂ O ₃ component is contained, the total amount of these components is 0.1. By setting the ratio to at least%, precipitation of the crystal phase containing the niobium component is further promoted, which can contribute to further improvement of the photocatalytic properties of the glass ceramic. Therefore, the total amount (TiO ₂ + ZrO ₂ + Al ₂ O ₃ ) with respect to the total amount of the oxide-converted composition is preferably 0.1%, more preferably 0.5%, and most preferably 1%.

The GeO ₂ component is a component having a function similar to that of the above-mentioned SiO ₂ and can be arbitrarily added to the glass ceramic of the present invention. In particular, by setting the content of the GeO ₂ component to 20% or less, the use of expensive GeO ₂ component can be suppressed, so that the material cost of the glass ceramic can be reduced. Therefore, the upper limit of the content of the GeO ₂ component with respect to the total amount of oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. The GeO ₂ component can be introduced into the glass ceramic using, for example, GeO ₂ as a raw material.

The Ga ₂ O ₃ component improves the stability of the glass, promotes the precipitation of the crystal phase containing the niobium component from the glass, and improves the photocatalytic properties by dissolving Ga ³⁺ ions in the crystal phase containing the niobium component. It is a component that contributes and can be optionally added. However, when the content exceeds 20%, the melting temperature is remarkably increased and vitrification becomes difficult. Therefore, the upper limit of the content of the Ga ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. Ga ₂ O ₃ component can be introduced into the glass ceramic is used as a raw material for instance _Ga 2 _{O 3,} GaF 3, and the like.

The In ₂ O ₃ component is a component having an effect similar to that of the above Al ₂ O ₃ and Ga ₂ O ₃ and can be optionally added. Since the In ₂ O ₃ component is expensive, the upper limit of its content with respect to the total amount of the oxide-converted composition is preferably 10% or less, more preferably 8% or less, and 5% or less. Is most preferred. The In ₂ O ₃ component can be introduced into glass ceramics using, for example, In ₂ O ₃ , InF ₃ or the like as a raw material.

The SnO component is a component that promotes the precipitation of crystals containing the niobium component and is effective in improving the photocatalytic properties by being dissolved in the crystal phase containing the niobium component, and has the effect of enhancing the photocatalytic activity, which will be described later. When added together with Ag, Au, or Pt ions, it serves as a reducing agent and is a component that indirectly contributes to improving the activity of the photocatalyst and can be added arbitrarily. However, if the content of these components exceeds 10%, the stability of the glass is deteriorated, and the photocatalytic properties are liable to deteriorate. Accordingly, the total content of the SnO component with respect to the total amount of the oxide-converted composition is preferably 10%, more preferably 8%, and most preferably 5%. When these components are added, the lower limit is preferably 0.01%, more preferably 0.02%, and most preferably 0.03%. SnO components can be introduced into the glass ceramic is used as a raw material for example _SnO, a SnO 2, SnO ₃ and the like.

The Bi ₂ O ₃ component is a component that increases the meltability and stability of the glass and contributes to the improvement of the photocatalytic properties, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, if the content of the Bi ₂ O ₃ component exceeds 20%, the stability of the glass is deteriorated and it is difficult to precipitate crystals containing the niobium component. Accordingly, the content of the Bi ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. The Bi ₂ O ₃ component can be introduced into the glass ceramic using, for example, Bi ₂ O ₃ as a raw material.

The TeO ₂ component is a component that increases the meltability and stability of the glass and contributes to the improvement of the photocatalytic properties, and can be optionally added. In addition, it is a component that lowers the glass transition temperature to facilitate generation of crystals containing a niobium component and suppresses the heat treatment temperature to a lower level. However, when the content of the TeO ₂ component exceeds 20%, the stability of the glass is deteriorated and it is difficult to precipitate crystals containing the niobium component. Therefore, the content of the TeO ₂ component with respect to the total amount of substances of the oxide conversion composition is preferably 20%, more preferably 15%, and most preferably 10%. The TeO ₂ component can be introduced into the glass ceramic using, for example, TeO ₂ as a raw material.

The WO ₃ component is a component that improves the meltability and stability of the glass, and is a component that improves the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or in the vicinity thereof. It is a component that can be added. However, if the content of the WO ₃ component exceeds 20%, the stability of the glass is remarkably deteriorated. Therefore, the upper limit of the content of the WO ₃ component with respect to the total amount of the oxide conversion composition is preferably 20%, more preferably 15%, and most preferably 10%. The WO ₃ component can be introduced into the glass ceramic using, for example, WO ₃ as a raw material.

The MoO ₃ component is a component that improves the meltability and stability of the glass, and is a component that improves the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or in the vicinity thereof. It is a component that can be added. However, when the content of the MoO ₃ component exceeds 20%, the stability of the glass is remarkably deteriorated. Therefore, the upper limit of the content of the MoO ₃ component with respect to the total amount of the oxide-converted composition is preferably 20%, more preferably 15%, and most preferably 10%. The MoO ₃ component can be introduced into the glass ceramic using, for example, MoO ₃ as a raw material.

As ₂ O ₃ component and / or Sb ₂ O ₃ component is a component for clarifying and defoaming glass, and when added together with Ag, Au, and Pt ions, which will be described later, and has the effect of enhancing photocatalytic activity. Since it plays the role of a reducing agent, it is a component that indirectly contributes to the improvement of the photocatalytic activity and can be optionally added. However, when the content of these components exceeds 5% in total, the stability of the glass is deteriorated, and the photocatalytic properties are liable to deteriorate. Accordingly, the total content of the As ₂ O ₃ component and / or Sb ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 5%, more preferably 3%, and most preferably 1%. To do. When these components are added, the lower limit is preferably 0.001%, more preferably 0.002%, and most preferably 0.005%. As ₂ O ₃ component and Sb ₂ O ₃ component are, for example, As ₂ O ₃ , As ₂ O ₅ , Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O and the like as raw materials. And can be introduced into glass ceramics.

The components for clarifying and defoaming the glass are not limited to the above As ₂ O ₃ component and Sb ₂ O ₃ component. For example, such as CeO ₂ component, TeO ₂ component, etc. Well-known fining agents and defoaming agents in the field, or a combination thereof can be used.

Ln ₂ O ₃ component (wherein Ln is selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) Is a component that enhances the chemical durability of the glass ceramics, and is a component that improves the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or in the vicinity thereof It is a component that can be optionally added. However, if the total content of the Ln ₂ O ₃ components exceeds 10%, the stability of the glass is significantly deteriorated. Therefore, the total amount of the Ln ₂ O ₃ component with respect to the total amount of the oxide-converted composition is preferably 10%, more preferably 8%, and most preferably 5%. The Ln ₂ O ₃ component includes, for example, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , CeO as raw materials. ₂ , CeF ₃ , Nd ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O _{3 and the} like can be used for introduction into the glass ceramic.

M _x O _y component (wherein M is at least one selected from the group consisting of V, Cr, Mn, Fe, Co, and Ni, and x and y are valences of x: y = 2: M, respectively) Is the component that contributes to the improvement of the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or in the vicinity thereof, and in the glass ceramic of the present invention. It is an optional component. In particular, when the total amount of the M _x O _y components is 10% or less, the stability of the glass ceramics can be improved and the appearance color of the glass ceramics can be easily adjusted. Accordingly, the total amount of the M _x O _y components with respect to the total amount of substances in the oxide conversion composition is preferably 10%, more preferably 8%, and most preferably 5%. When these components are added, the lower limit is preferably 0.0001%, more preferably 0.002%, and most preferably 0.005%.

The glass ceramic of the present invention may contain at least one nonmetallic element component selected from the group consisting of an F component, a Cl component, and a Br component. These components are components that improve the photocatalytic properties by being dissolved in the crystal phase containing the niobium component or existing in the vicinity thereof, and can be optionally added. However, when the content of these components exceeds 15% in total, the stability of the glass is remarkably deteriorated, and the photocatalytic properties are easily lowered. Accordingly, in order to ensure good characteristics, the total of the externally divided mass ratio of the content of the nonmetallic element component to the total mass of the glass ceramic of the oxide conversion composition is preferably 15%, more preferably 10%, most preferably The upper limit is 5%. These non-metallic element components are preferably introduced into the glass ceramic in the form of alkali metal or alkaline earth metal fluoride, chloride, bromide, sulfide, nitride, carbide or the like. Note that the content of the non-metallic element component in this specification is assumed to be made of an oxide in which all of the cation components constituting the glass ceramic are combined with oxygen that balances the charge, and the glass made of these oxides. The total mass is 100%, and the mass of the nonmetallic element component is expressed in mass% (extra divided mass% with respect to the oxide-based mass). The raw material of the nonmetallic element component is not particularly limited. For example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ , etc. are used as the F component raw material, NaCl, AgCl, etc. are used as the Cl component raw material, and NaBr is used as the Br component raw material. Thus, it can be introduced into the glass ceramic. These raw materials may be added in combination of two or more, or may be added alone.

The glass ceramic of the present invention may contain at least one metal element component selected from a Cu component, an Ag component, an Au component, a Pd component, and a Pt component. These metal element components are components that improve the photocatalytic activity by being present in the vicinity of the crystal phase containing the niobium component, and can be optionally added. However, if the total content of these metal element components exceeds 5%, the stability of the glass is remarkably deteriorated, and the photocatalytic properties tend to be lowered. Therefore, the total of the externally divided mass ratio of the content of the metal element component with respect to the total mass of the glass ceramic of the oxide conversion composition is preferably 5%, more preferably 3%, and most preferably 1%. These metal element components can be introduced into glass ceramics using, for example, CuO, Cu ₂ O, Ag ₂ O, AuCl ₃ , PtCl ₂ , PtCl ₄ , H ₂ PtCl ₆ , PdCl ₂ or the like as raw materials. In addition, the content of the metal element component in this specification is assumed to be made of an oxide in which all the cation components constituting the glass ceramic are combined with oxygen sufficient to balance the charge, and the entire glass made of these oxides. The mass of the metal element component is expressed in terms of mass% (externally divided mass% with respect to the oxide-based mass). When these components are added, the lower limit is preferably 0.0001%, more preferably 0.002%, and most preferably 0.005%.

  Components other than the above components can be added to the glass ceramic of the present invention as necessary within a range not impairing the properties of the glass ceramic. However, lead compounds such as PbO, and components of Th, Cd, Tl, Os, Se, and Hg tend to refrain from being used as harmful chemical substances in recent years. Environmental measures are required until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the glass ceramics are substantially free of substances that pollute the environment. Therefore, the glass ceramics can be manufactured, processed, and discarded without taking any special environmental measures.

The glass ceramics of the present invention cannot be expressed directly in the description of mass% because the composition is expressed in mol% with respect to the total amount of the oxide-converted composition, but the characteristics required in the present invention are not included. The composition expressed by mass% of each component present in the composition to be filled generally takes the following values in terms of oxide conversion.
Nb ₂ O ₅ component 8 to 80% by mass
And SiO ₂ component 15 to 50% by mass and / or B ₂ O ₃ component 15 to 50% by mass and / or P ₂ O ₅ component 10 to 50% by mass and / or Li ₂ O component 0 to 20% by mass and / or Na ₂ O component 0-25% by mass and / or K ₂ O component 0-25% by mass and / or MgO component 0-25% by mass and / or CaO component 0-30% by mass and / or SrO component 0-30% by mass % And / or BaO component 0 to 30% by mass and / or Ta ₂ O ₅ component 0 to 70% by mass and / or TiO ₂ component 0 to 20% by mass and / or ZrO ₂ component 0 to 15% by mass and / or Al ₂ O ₃ component 0-20% by weight and / or GeO ₂ component 0 to 10% by weight and / or Ga ₂ O ₃ component 0 to 15 wt% and / or In ₂ O ₃ component 0 to 10% by weight and / or S O components 0 to 10% by weight and / or Bi ₂ O ₃ component 0-30% by weight and / or TeO ₂ component 0-30% by weight and / or WO ₃ ingredient 0-30% by weight and / or MoO ₃ ingredients 0 10% by mass and / or As ₂ O ₃ component and Sb ₂ O ₃ component 0 to 5% by mass in total
Ln ₂ O ₃ component in total 0-15 mass% and / or M _x O _y component in total 0-10 mass% and / or
With respect to 100% of the total mass of the glass ceramic of the oxide conversion composition,
At least one non-metallic element component selected from the group consisting of F component, Cl component, Br component, S component, N component, and C component, and / or Cu component, Ag component, Au component, 0 to 5% by mass of at least one metal element component selected from the group consisting of a Pd component and a Pt component

Further, the glass ceramic of the present invention has a crystal phase composed of one or more of Nb ₂ O ₅ , RnNbO ₃ , RNb ₂ O ₆ , R ₂ Nb ₂ O ₇ and a solid solution thereof in a volume ratio of 1 to the total volume of the glass. It is preferable to contain within a range of not less than 95% and not more than 95% (wherein Rn is at least one selected from Li, Na, K, and R is one selected from Mg, Ca, Sr, Ba and Zn) And above). When the content of these crystal phases is 1% or more, the glass ceramic can have good photocatalytic properties. On the other hand, when the content of the crystal phase is 95% or less, the glass ceramic can obtain good mechanical strength.

  Further, the crystallization rate of the glass ceramic of the present invention is preferably 1%, more preferably 3%, most preferably 5% in the volume ratio, preferably 98%, more preferably 95%, most preferably. The upper limit is 90%. As for the size of the crystal, it is preferable that the average particle size when approximated to a sphere is 200 nm or less. It is possible to control the size of the precipitated crystal phase by controlling the heat treatment conditions. However, in order to simultaneously impart transparency and effective photocatalytic properties of the glass ceramic, the crystal size is set to 200 nm or less. It is preferable that the range be 150 nm to 5 nm, and it is most preferable that the range be 100 nm to 10 nm. However, when the transparency of the glass ceramic is not taken into consideration, the crystal size may be larger than 200 nm. In addition, when the refractive index of the glass phase and the crystal phase in the glass ceramic is approximate, transparency is obtained regardless of the size of the crystal, so there is no restriction on the size of the crystal, and it becomes larger than 200 nm. It doesn't matter. The crystal grain size and the average value can be estimated from Scherrer's formula from the half width of the XRD diffraction peak. If the diffraction peaks are weak or overlap, measure the diameter of the crystal particle area measured using a scanning electron microscope (SEM) or transmission electron microscope (TEM), assuming that this is a circle. it can. When calculating an average value using a microscope, it is preferable to measure 100 or more crystal diameters at random.

  The glass ceramic of the present invention preferably exhibits catalytic activity by light having a wavelength from the ultraviolet region to the visible region. Here, the light having a wavelength in the ultraviolet region referred to in the present invention is an invisible electromagnetic wave having a wavelength shorter than that of visible light and longer than that of soft X-ray, and the wavelength is in the range of approximately 10 to 400 nm. In addition, the light having a wavelength in the visible region referred to in the present invention is an electromagnetic wave having a wavelength that can be seen by human eyes among electromagnetic waves, and the wavelength is in a range of about 400 nm to 700 nm. When the surface of the glass ceramic is irradiated with light of any wavelength from the ultraviolet region to the visible region, or light of a composite wavelength of these, the catalytic activity is exhibited, and the light adheres to the surface of the glass ceramic. Since dirt substances, bacteria, etc. are decomposed by oxidation or reduction reaction, glass ceramics can be used for antifouling and antibacterial applications.

  The glass ceramic of the present invention preferably has a contact angle of 30 ° or less between the surface irradiated with light having a wavelength from the ultraviolet region to the visible region and a water droplet. Thereby, since the surface of the glass ceramic exhibits hydrophilicity and has a self-cleaning action, the surface of the glass ceramic can be easily washed with water, and the deterioration of the photocatalytic properties due to dirt can be suppressed. The contact angle between the glass ceramic surface irradiated with light and the water droplet is preferably 30 ° or less, more preferably 25 ° or less, and most preferably 20 ° or less.

  Further, the glass ceramic of the present invention preferably has a methylene blue decomposition activity index of 3.0 nmol / L / min or more based on JIS R 1703-2: 2007. Photocatalysts have the ability to generate strong oxidizing power when exposed to ultraviolet light, and to decompose the organic matter they touch into carbon dioxide and water. This is called oxidative decomposition performance and can be evaluated by the following self-cleaning performance test. The test piece is brought into contact with water in which an organic dye (methylene blue) is dissolved, and the initial absorbance (degree of light absorption) is measured with a spectrophotometer. Repeat the operation of measuring the absorbance by irradiating with ultraviolet rays for a certain period of time. Since the dye is decomposed by the photocatalyst, the concentration of the solution gradually decreases and becomes transparent, and the absorbance decreases. The degradation rate of the dye can be calculated from the change in concentration over time, and this is an index of the self-cleaning performance (oxidative degradation performance) of the test piece.

[Glass ceramic production method]
Next, the manufacturing method of the glass ceramic of this invention is demonstrated. However, the manufacturing method of the glass ceramic of this invention is not limited to the method shown below. The glass ceramic manufacturing method of the present embodiment includes a melting step of mixing raw materials to obtain a melt, a cooling step of cooling the melt to obtain glass, and the temperature of the glass to a crystallization temperature range. A reheating step for raising the temperature, a crystallization step for maintaining the temperature within the crystallization temperature region to produce crystals, and a recooling step for reducing the temperature outside the crystallization temperature region to obtain glass ceramics. , Can have.

(Melting process)
The melting step is a step of obtaining a melt by mixing raw materials having the above-described composition. More specifically, the raw materials are prepared so that each component of the glass ceramic is within a predetermined content range, mixed uniformly, and the prepared mixture is put into a platinum crucible, quartz crucible or alumina crucible. Melt for 1 to 24 hours in a temperature range of 1200 to 1600 ° C. in an electric furnace, and homogenize with stirring to prepare a melt. The conditions for melting the raw material are not limited to the above temperature range, and can be appropriately set according to the composition and blending amount of the raw material composition.

(Cooling process)
The cooling step is a step of producing glass by cooling and vitrifying the melt obtained in the melting step. Specifically, a vitrified glass body is formed by flowing out the melt and appropriately cooling it. Here, the conditions for vitrification are not particularly limited, and may be appropriately set according to the composition and amount of the raw material. Moreover, the shape of the glass body obtained at this process is not specifically limited, Although it may be plate shape, a granular form, etc., it is preferable that it is plate shape at the point which can produce a glass body rapidly and in large quantities.

(Reheating process)
The reheating step is a step of raising the temperature of the glass obtained in the cooling step to the crystallization temperature region. In this step, since the temperature rising rate and temperature have a great influence on the formation of crystal phase and the crystal size, it is important to control them precisely.

(Crystallization process)
The crystallization step is a step of generating crystals such as Nb ₂ O ₅ , RnNbO ₃ , and RNb ₂ O ₆ by holding them for a predetermined time in the crystallization temperature region. By maintaining the crystallization temperature in the crystallization temperature region for a predetermined time in this crystallization step, crystals of Nb ₂ O ₅ , RnNbO ₃ , RNb ₂ O _6, etc. having a desired size from nano to micron units are uniformly formed inside the glass body It can be dispersed in The crystallization temperature region is, for example, a temperature region exceeding the glass transition temperature. Since the glass transition temperature varies depending on the glass composition, it is preferable to set the crystallization temperature according to the glass transition temperature. The crystallization temperature region is preferably a temperature region that is 10 ° C. or more higher than the glass transition temperature, more preferably 15 ° C. or more, and most preferably 20 ° C. or more. The lower limit of the preferred crystallization temperature region is 450 ° C, more preferably 500 ° C, and most preferably 550 ° C. On the other hand, if the crystallization temperature is too high, an unknown phase other than the target tends to be precipitated and the photocatalytic properties are easily lost. Therefore, the upper limit of the crystallization temperature region is preferably 1200 ° C, more preferably 1100 ° C. 1000 ° C. is most preferable. In this step, the rate of temperature increase and the temperature greatly affect the size of the crystal, so it is important to appropriately control according to the composition and the heat treatment temperature. The heat treatment time for crystallization needs to be set under conditions that allow crystals to grow to a certain extent and precipitate a sufficient amount of crystals according to the glass composition, heat treatment temperature, and the like. The heat treatment time can be set in various ranges depending on the crystallization temperature. If the rate of temperature increase is slow, it may be only necessary to heat to the heat treatment temperature. However, as a guideline, it is preferable that the temperature is short when the temperature is high and long when the temperature is low. The crystallization process may go through a one-stage heat treatment process, or may go through two or more heat treatment processes.

(Recooling process)
The recooling step is a step of obtaining glass ceramics having a crystal phase such as Nb ₂ O ₅ , RnNbO ₃ , and RNb ₂ O ₆ by lowering the temperature outside the crystallization temperature region after crystallization is completed.

  In addition, the solution is cooled while controlling the cooling rate without passing through the crystallization process by vitrification and reheating, and the crystallization temperature region is passed through the crystallization temperature region for a predetermined time in the cooling process, so that it is directly from the liquid. By precipitating a crystal phase containing a niobium component, it is possible to produce a target glass ceramic.

(Etching process)
Glass ceramics after the formation of crystals can exhibit high photocatalytic properties as they are or after being subjected to mechanical processing such as polishing, but by etching the glass ceramics, Since the glass phase around the crystal phase is removed and the specific surface area of the crystal phase exposed on the surface is increased, the photocatalytic properties of the glass ceramic can be further enhanced. Further, by controlling the solution used in the etching step and the etching time, it is possible to obtain a porous body in which a crystal phase containing niobium oxide crystals, niobate crystals and / or solid solutions thereof remains. Here, examples of the etching method include dry etching, wet etching by immersion in a solution, and a combination thereof. The acidic or alkaline solution used for the immersion is not particularly limited as long as the surface of the glass ceramic can be corroded, and may be, for example, an acid containing fluorine or chlorine (hydrofluoric acid, hydrochloric acid). This etching step may be performed by spraying hydrogen fluoride gas, hydrogen chloride gas, hydrofluoric acid, hydrochloric acid, or the like on the surface of the glass ceramic.

  In the said manufacturing method, a shaping | molding process can be provided as needed and a glass or glass ceramics can be processed into arbitrary shapes.

[photocatalyst]
The glass ceramic produced as described above can be used as a photocatalyst as it is or after being processed into an arbitrary shape. Here, the “photocatalyst” may have any shape such as a bulk state or a powder form. This photocatalyst can be used, for example, as a photocatalyst material, a photocatalyst member (for example, a water purification material, an air purification material, etc.), a hydrophilic material, a hydrophilic member (for example, a window, a mirror, a panel, a tile, or the like).

[Glass ceramic compact]
A preferred example in the case of applying the glass ceramics of the present invention to a photocatalyst will be described. The glass ceramic of the present invention can be used for various machines, devices, instruments and the like as a photocatalytic functional glass ceramic molded body and / or a hydrophilic glass ceramic molded body by molding into an arbitrary shape. In particular, it is preferably used for applications such as tiles, window frames, and building materials. Thereby, since the photocatalytic function is exhibited on the surface of the glass ceramic molded body and the fungi attached to the surface of the glass ceramic molded body are sterilized, the surface can be kept hygienic when used in these applications. In addition, since the surface of the glass ceramic molded body has hydrophilicity, dirt attached to the surface of the glass ceramic molded body when used in these applications can be easily washed away with raindrops or the like.

  Moreover, the glass-ceramic molded object of this invention can be processed into a various form according to a use. In particular, for example, by adopting the form of glass beads or glass fibers (glass fibers), the exposed area of the crystal phase containing the niobium component increases, so that the photocatalytic activity of the glass ceramic molded body can be further increased. Hereinafter, glass beads and glass fibers will be described as examples of typical processing forms of glass ceramics.

[Glass beads]
The glass beads in the present invention relate to industrial beads, not decorative or handcraft beads. Industrial beads are mainly made of glass due to advantages such as durability, and generally glass microspheres (diameters from several μm to several mm) are called glass beads. Typical applications include road sign boards, paints used on road surface display lines, reflective cloths, filter media, and blasting abrasives. When glass beads are mixed and dispersed in road sign paints, reflective cloths, etc., light emitted from car lights etc. at night is reflected (retroreflected) through the beads to improve visibility. These functions of glass beads are also used in jogging wear, construction waistcoats, motorcycle driver vests, and the like. When the glass ceramic beads of the present invention are mixed in the paint, the photocatalytic function decomposes the dirt adhering to the sign plate and the line, so that a clean state can be always maintained and maintenance work can be greatly reduced. Furthermore, the glass ceramic beads of the present invention can have a retroreflective function and a photocatalytic function at the same time by adjusting the composition, the size of precipitated crystals, and the amount of crystal phase. In order to obtain glass ceramic beads having higher retroreflectivity, the refractive index of the glass matrix phase and / or crystal phase constituting the beads is preferably in the range of 1.8 to 2.1, In particular, around 1.9 is more preferable.

  As other applications, industrial glass beads are used as filter media. Glass beads, unlike sand and stone, are all spherical and have a high filling rate and can calculate porosity, so they are widely used alone or in combination with other filter media. The glass ceramic beads of the present invention have a photocatalytic function in addition to the original functions of such glass beads. In particular, it does not have a film or a coating layer, and exhibits photocatalytic properties as a single substance, so that there is no deterioration of catalytic activity due to peeling, and labor and time for replacement and maintenance can be saved. In addition, the filter member and the purification member using the photocatalytic function are often adjacent to the light source member in the apparatus. However, the glass ceramic beads are preferably accommodated in a container in the apparatus. Available.

  Furthermore, since glass beads are excellent in chemical stability and are spherical, they do not damage the workpiece so much and are used for blasting materials. Blasting refers to performing cleaning, beautification, peening, and the like by jetting granular material and causing it to collide with the surface to be processed. Since the glass ceramic beads of the present invention have a photocatalytic function in addition to the merits, simultaneous processing using a photocatalytic reaction at the same time as blasting is possible.

  The particle size of the glass beads of the present invention can be appropriately determined according to the application. For example, when blended in a paint, the particle size can be 100-2500 μm, preferably 100-2000 μm. When used for a reflective cloth, the particle diameter can be 20-100 μm, preferably 20-50 μm. When used as a filter medium, the particle size can be 30 to 8000 μm, preferably 50 to 5000 μm.

  Next, the manufacturing method of the glass ceramic bead of this invention is demonstrated. The method for producing glass ceramic beads of the present invention includes a melting step of mixing raw materials to obtain a melt thereof, a molding step of forming a bead body using the melt or glass obtained from the melt, and the temperature of the bead body. Can be included in a crystallization temperature region exceeding the glass transition temperature, and kept at that temperature for a predetermined time to precipitate a desired crystal. In addition, since the general manufacturing method of the said glass ceramics can be applied to this specific example in the range which does not contradict, they are used suitably and the overlapping description is abbreviate | omitted.

(Melting process)
It can carry out similarly to the said general manufacturing method.

(Molding process)
Then, it shape | molds from the melt obtained at the melting process to a fine bead body. There are various methods for forming the bead body, which may be selected as appropriate. In general, the bead body can be formed by following the process of glass melt or glass → pulverization → particle size adjustment → spheronization. In the pulverization step, the cooled and solidified glass is pulverized, or the molten glass is poured into water and pulverized, or further pulverized by a ball mill to obtain granular glass. Then, adjust the particle size using a sieve, etc., reheat to form a spherical shape with surface tension, put it into a drum together with a powder material such as graphite, and shape it into a spherical shape with physical force while rotating, etc. There is a way. Or it can also take the method of making it spheroidize directly from a molten glass, without passing through a grinding | pulverization process. For example, molten glass is jetted into the air to spheroidize by surface tension, molten glass that exits from the outflow nozzle is cut into pieces with a member such as a rotating blade, and spheroidized. There is a method of making it spherical. Usually, the molded beads are commercialized after the particle size is adjusted again. In view of the viscosity of the glass at the molding temperature and the easiness of devitrification, the most suitable method may be selected from these methods.

(Crystallization process)
The bead body obtained by the above process is reheated to perform a crystallization step for depositing desired crystals. In the crystallization step, it is necessary to set the crystallization temperature in accordance with the glass transition temperature for each glass composition. Specifically, it is preferable to perform heat treatment in a temperature range higher than the glass transition temperature by 10 ° C. or more. For example, when the glass transition temperature is 500 ° C. or higher, the lower limit of the preferable heat treatment temperature is 510 ° C., more preferably 520 ° C., and most preferably 530 ° C. On the other hand, if the heat treatment temperature becomes too high, Nb ₂ O ₅ , RnNbO ₃ , RNb ₂ O ₆ (Rn is at least one selected from Li, Na, and K, and R is Mg, Ca, Sr, Ba and The tendency to decrease the crystal phase (meaning one or more selected from Zn) becomes strong, and the photocatalytic properties tend to disappear. Therefore, the upper limit of the heat treatment temperature is preferably 1200 ° C, more preferably 1100 ° C, and most preferably 1050 ° C. When the temperature is higher than 1200 ° C., precipitation of crystals such as Nb ₂ O ₅ , RnNbO ₃ , and RNb ₂ O ₆ decreases. Since the temperature and time of crystallization have a great influence on the formation of crystal phase and the crystal size, it is very important to control them precisely. When a desired crystal is obtained, it is cooled outside the crystallization temperature region to obtain glass ceramic beads in which the crystal is dispersed.

  In addition to the method of crystallization after forming the bead body as described above, the crystal phase may be precipitated in the process of spheroidizing and cooling directly from the melt.

  The glass ceramic beads after the formation of crystals by performing the crystallization process can exhibit high photocatalytic properties as they are, but by performing an etching process on the glass ceramic beads, Since the surrounding glass phase is removed and the specific surface area of the crystal phase exposed on the surface increases, the photocatalytic properties of the glass ceramic beads can be further enhanced. In addition, by controlling the solution used in the etching process and the etching time, it is possible to obtain porous beads in which only the photocatalytic crystal phase remains. The etching process can be performed in the same manner as described above.

[Glass ceramic fiber]
The glass ceramic fiber of the present invention has the general properties of glass fiber. In other words, it has higher tensile strength and specific strength than conventional fibers, large elastic modulus and specific modulus, good dimensional stability, high heat resistance, nonflammability, good chemical resistance, etc. It has merits and can be used for various purposes. Moreover, since it has a photocatalytic crystal inside and on the surface of the fiber, it is possible to provide a fiber structure having photocatalytic properties in addition to the above-described merits and applicable to a wider range of fields. Here, the fiber structure refers to a three-dimensional structure in which fibers are formed as a woven fabric, a knitted fabric, a laminate, or a composite thereof, and examples thereof include a nonwoven fabric.

  There are curtains, sheets, wall-clothing cloths, insect screens, clothes, or heat insulating materials, etc. as applications that make use of heat resistance and nonflammability of glass fibers. The article can be given a deodorizing function, a dirt decomposing function, etc. by photocatalytic action, and the labor of cleaning and maintenance can be greatly reduced.

  In addition, glass fiber is often used as a filtering material because of its chemical resistance, but the glass ceramic fiber of the present invention is not only filtered, but also a malodorous substance, dirt, bacteria, etc. in the object to be treated by a photocatalytic reaction. Therefore, it is possible to provide a purification device and a filter having a more active purification function. Furthermore, since the deterioration of the characteristics due to the separation / detachment of the photocatalyst layer hardly occurs, it contributes to extending the life of these products.

  Next, the manufacturing method of the glass ceramic fiber of this invention is demonstrated. The method for producing glass ceramic fibers of the present invention includes a melting step of mixing raw materials to obtain a melt thereof, a spinning step of forming into a fiber form using the melt or glass obtained from the melt, and the temperature of the fibers. May be included in a temperature range exceeding the glass transition temperature, and held at that temperature for a predetermined time to precipitate a desired crystal. In addition, since the general manufacturing method of the said glass ceramics can be applied to this specific example in the range which does not contradict, they are used suitably and the overlapping description is abbreviate | omitted.

(Melting process)
It can carry out similarly to the said general manufacturing method.

(Spinning process)
Next, it shape | molds from the melt obtained at the melting process to glass fiber. The method for forming the fiber body is not particularly limited, and may be formed using a known method. When forming into a fiber (long fiber) of a type that can be continuously wound on a winder, it may be spun by a known DM method (direct melt method) or MM method (marble melt method), and the fiber length is several tens of centimeters. When forming into short fibers having a degree, a centrifugal method may be used, or the long fibers may be cut. What is necessary is just to select a fiber diameter suitably with a use. However, the thinner the fabric, the higher the flexibility and texture. However, the spinning production efficiency and cost increase, and conversely, if it is too thick, the spinning productivity is improved, but the workability and handleability are poor. Become. When making a textile product such as a woven fabric, the fiber diameter is preferably in the range of 3 to 24 μm, and when making a laminated structure suitable for uses such as a purification device and a filter, the fiber diameter should be 9 μm or more. preferable. Then, depending on the application, it can be made into a cotton shape, or a fiber structure such as roving or cloth can be made.

(Crystallization process)
Next, the fiber or the fiber structure obtained by the above process is reheated to perform a crystallization step for depositing desired crystals in and on the fiber. This crystallization step can be performed in the same manner as the crystallization step of glass beads. When a desired crystal is obtained, the glass ceramic fiber or the fiber structure in which the photocatalytic crystal is dispersed can be obtained by cooling to outside the crystallization temperature region.

  In addition to the method of crystallizing after forming the fiber body as described above, the temperature of the glass fiber in the spinning process may be controlled so that the crystallization process is performed simultaneously.

  The glass ceramic fiber after the crystallization process has produced crystals can exhibit high photocatalytic properties even if it remains as it is. However, by performing an etching process on this glass ceramic fiber, Since the surrounding glass phase is removed and the specific surface area of the crystal phase exposed on the surface is increased, the photocatalytic properties of the glass ceramic fiber can be further enhanced. Further, by controlling the solution used in the etching process and the etching time, it is possible to obtain a porous fiber in which only the photocatalytic crystal phase remains. The etching process can be performed in the same manner as described above.

  As described above, the glass ceramic of the present invention is excellent because the crystal phase of niobium oxide crystal, niobate salt and / or solid solution thereof having photocatalytic activity is uniformly precipitated inside and on the surface. In addition to having photocatalytic activity and visible light responsiveness, it also has excellent durability. Therefore, unlike the conventional photocatalytic functional member in which the photocatalyst layer is provided only on the surface of the substrate, the photocatalyst layer is not peeled off and the photocatalytic activity is not lost. Even if the surface is scraped, the niobium oxide crystals, niobate crystals and / or crystal phases of the solid solutions thereof are exposed and the photocatalytic activity is maintained. Further, since the glass ceramic of the present invention can be produced from a molten glass, it has a high degree of freedom in processing the size and shape and can be processed into various articles that require a photocatalytic function.

  Further, according to the method for producing glass ceramics of the present invention, crystals of niobium oxide, crystals of niobate and / or crystal phases of their solid solutions can be generated by controlling the composition of raw materials and the heat treatment temperature. Thus, the labor required for the refinement of crystal particles, which has been a major problem in the photocatalytic technology, is unnecessary, and glass ceramics having excellent photocatalytic activity and visible light response can be easily produced on an industrial scale.

  EXAMPLES Next, although an Example demonstrates this invention in more detail, this invention is not restrict | limited to a following example.

Examples 1 to 23:
Tables 1 to 4 show the compositions of the glass ceramics of Examples 1 to 23 of the present invention, the crystallization temperatures, and the types of main crystal phases precipitated on these glass ceramics. The glass ceramics of Examples 1 to 23 are used for ordinary glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and metaphosphate compounds corresponding to the raw materials of the respective components. A high purity raw material was selected and used. These raw materials were weighed so as to have the composition ratios of the respective examples shown in Tables 1 to 4 and mixed uniformly, and then put into a platinum crucible, which was then heated in an electric furnace according to the melting difficulty of the glass composition. It melt | dissolved for 1 to 24 hours in the temperature range of 1250 degreeC-1580 degreeC, and stirred and homogenized, and performed foaming etc. Thereafter, the temperature was lowered to 1450 ° C. or lower, and the mixture was homogenized with stirring, cast into a mold, and slowly cooled to produce glass. The obtained glass was heated to the crystallization temperature described in each example of Tables 1 to 4 and held for the described time for crystallization. Then, it cooled from the crystallization temperature and obtained the glass ceramic which has the target crystal phase.

  Here, the kind of the precipitated crystal phase of the glass ceramics of Examples 1 to 23 was identified by an X-ray diffractometer (manufactured by Philips, trade name: X′Pert-MPD).

As shown in Tables 1 to 4, the precipitated crystal phases of the glass ceramics of Examples 1 to 23 all have high photocatalytic activity NaNbO ₃ crystal, LiNbO ₃ crystal, Na (Nb, Ta) O ₃ crystal, Li (Nb, Ta) O ₃ crystal, (Na, K) NbO ₃ crystal, and (Na, Li) NbO ₃ crystal were contained as the main crystal phase. The size of the NaNbO ₃ crystal was estimated from the half width of the XRD diffraction peak based on the Scherrer equation; D = 0.9λ / (βcosθ). Here, D is the crystal size, λ is the X-ray wavelength, and θ is the Bragg angle (half the diffraction angle 2θ). The results are as shown in Table 5, and it was confirmed that the size of NaNbO ₃ crystal or the like was 200 nm or less.

Next, in order to investigate the structure of the NaNbO ₃ crystal, each of Examples 1, 2, and 12 was crystallized under different crystallization conditions (temperature, time), and X-ray diffraction analysis (XRD) was performed. The crystallization conditions and XRD results are shown in FIG. 1 (Example 1), FIG. 2 (Example 2) and FIG. 3 (Example 12). By performing heat treatment for crystallization, in the XRD patterns of FIGS. 1 to 3, peaks represented by “◯” near the incident angle 2θ = 22.7 ° and near the incident angle 2θ = 46.3 °. The presence of NaNbO ₃ cubic crystals or Na (Nb, Ta) O ₃ cubic crystals was confirmed. Therefore, the glass ceramics of Examples 1, 2, and 12 were considered to have photocatalytic activity.

Moreover, it became clear from the results of FIGS. 1 to _{3 that} the crystal structure of NaNbO ₃ or Na (Nb, Ta) O ₃ can be controlled by changing the crystallization conditions. It was also found that the higher the crystallization temperature, and the longer the heat treatment time at the same crystallization temperature, the more crystal precipitation.

Further, the hydrophilicity of some glass ceramics of Examples 1 to 23 was evaluated by measuring the contact angle between the sample surface and water droplets by the θ / 2 method. That is, after the sample was etched with hydrofluoric acid for 2 minutes, water was dropped on the surface of the glass ceramic before and after the ultraviolet irradiation, the height h from the surface of the glass ceramic to the top of the water droplet, and a test piece of water droplet Is measured with a contact angle meter (DM501) manufactured by Kyowa Interface Science Co., Ltd., and the contact angle θ with water is calculated from the relational expression θ = 2 tan ⁻¹ (h / r). Asked. The ultraviolet irradiation was performed using a mercury lamp with an illuminance of 10 mW / cm ² and an irradiation time of 10 to 60 minutes. The results of evaluating the hydrophilicity of the glass ceramics of Examples 1, 2, and 12 manufactured by changing the crystallization conditions typically after etching the surface with hydrofluoric acid (HF) are shown in FIGS. As shown in FIGS. 4 and 5, in Examples 1 and 2, it was confirmed that the contact angle with water was 10 ° or less by irradiation with ultraviolet rays for approximately 10 minutes. As shown in FIG. 6, in Example 12, it was confirmed that the contact angle with water was 20 ° or less by irradiation with ultraviolet rays for 60 minutes at the maximum. Thereby, it became clear that the glass ceramic of the Example of this invention has high hydrophilicity. It was also found that the hydrophilicity increases as the crystallization temperature is increased and the heat treatment time is increased at the same crystallization temperature.

Moreover, using the composition of Example 1, beads having a diameter of 500 μm and glass fibers having a diameter of 50 μm were prepared. As a result, precipitation of NaNbO ₃ crystal phase having a size of 100 nm or less was confirmed after the heat treatment.

As the above experimental results showed, the glass ceramics of Examples 1 to 23 containing a crystal phase containing NaNbO ₃ crystals had photocatalytic activity. Moreover, since the NaNbO ₃ crystals are uniformly dispersed in the glass, it was confirmed that there is no loss of the photocatalytic function due to peeling and that it can be used as a photocatalytic functional material excellent in durability.

As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment. Those skilled in the art can make many modifications without departing from the spirit and scope of the present invention, and these are also included within the scope of the present invention.

Claims (29)

  Glass ceramics containing a crystal phase containing a niobium component and having photocatalytic activity. _2. The glass ceramic according to claim 1, comprising 5 to 50% of Nb ₂ O ₅ component in mol% with respect to the total amount of the oxide-converted composition. The crystal phase is RnNbO ₃ crystal, RNb ₂ O ₆ crystal (Rn is one or more selected from Li, Na, and K, and R is one or more selected from Mg, Ca, Sr, Ba, and Zn. The glass ceramics according to claim 1 or 2, comprising at least one crystal selected from the group consisting of these solid solutions. 30% to 75% of one or more components selected from the group consisting of SiO ₂ component, B ₂ O ₃ component, and P ₂ O ₅ component in mol% with respect to the total substance amount of oxide conversion composition The glass ceramic according to claim 1, which is contained. 5. The glass according to claim 4, containing 5 to 40% of Rn ₂ O and / or RO components (Rn and R have the same meaning as above) in mol% with respect to the total amount of the oxide-converted composition. Ceramics. The glass ceramic according to claim 5, further comprising 0 to 35% of Ta ₂ O ₅ component in mol% with respect to the total amount of the oxide-converted composition. The glass ceramic according to claim 6, further comprising, in mol%, a TiO ₂ component and / or a ZrO ₂ component 0 to 20% with respect to the total amount of the oxide-converted composition. The glass ceramic according to claim 7, further comprising, in mol%, 0 to 30% of an Al ₂ O ₃ component with respect to the total amount of the oxide-converted composition. The Nb ₂ O ₅ and / or Ta ₂ O ₅ , and TiO _{2 with} respect to the total amount of the Rn ₂ O and / or RO components (Rn and R have the same meaning as described above) in a molar ratio of oxide equivalent composition , Ratio of the total amount of one or more components selected from the group consisting of ZrO ₂ and Al ₂ O ₃ [(Nb ₂ O ₅ + Ta ₂ O ₅ + TiO ₂ + ZrO ₂ + Al ₂ O ₃ ) / (Rn ₂ O + RO) ] Is larger than 1. The glass ceramic according to claim 8. In mol% with respect to the total amount of substances of oxide equivalent composition,
GeO ₂ component 0-20% and / or Ga ₂ O ₃ component 0-20% and / or In ₂ O ₃ component 0-10% and / or SnO component 0-10% and / or Bi ₂ O ₃ components 0-20% and / or TeO ₂ components 0-20% and / or WO ₃ components 0-20% and / or MoO ₃ components 0-20% and / or As ₂ O ₃ components and / or Or Sb ₂ O ₃ component Total 0-5%
The glass ceramic according to any one of claims 1 to 9, further comprising: Ln ₂ O ₃ component (wherein Ln is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, in mol% with respect to the total amount of oxide-converted composition) The glass ceramic according to any one of claims 1 to 10, comprising 0 to 10% in total of at least one selected from the group consisting of Ho, Er, Tm, Yb, and Lu. M _x O _y component (wherein M is one or more selected from the group consisting of V, Cr, Mn, Fe, Co, and Ni) in mol% with respect to the total amount of the oxide-converted composition. The glass according to any one of claims 1 to 11, wherein x and y are the minimum natural numbers satisfying x: y = 2: M valence, respectively, in a total of 0 to 10%. Ceramics.   The glass ceramic according to any one of claims 1 to 12, wherein the glass ceramic contains at least one component selected from the group consisting of F, Cl, and Br in an externally divided mass ratio of 15% or less with respect to the total mass of the glass.   14. The glass ceramic according to claim 1, comprising at least one component selected from the group consisting of Cu, Ag, Au, Pd, and Pt in an externally divided mass ratio of 5% or less with respect to the total mass of the glass. .   The glass ceramic according to any one of claims 1 to 14, wherein a contact angle between a surface irradiated with light having a wavelength from an ultraviolet region to a visible region and a water droplet is 30 ° or less.   The glass ceramic according to any one of claims 1 to 15, wherein a decomposition activity index of methylene blue based on JIS R 1703-2: 2007 is 3.0 nmol / L / min or more.   The glass ceramic according to any one of claims 1 to 16, wherein an average crystal grain size when approximated to a sphere is 200 nm or less.   A photocatalytic functional glass-ceramic shaped article comprising the glass-ceramic according to any one of claims 1 to 17.   The hydrophilic glass-ceramics molded object containing the glass ceramic in any one of Claim 1 to 17.   A photocatalyst comprising the glass ceramic according to claim 1.   The photocatalyst according to claim 20, which has a shape of a fiber or a bead.   The photocatalyst material containing the photocatalyst in any one of Claim 20 or 21.   The photocatalyst member containing the photocatalyst body in any one of Claim 20 or 21.   A hydrophilic material comprising the photocatalyst according to claim 20.   The hydrophilic member containing the photocatalyst in any one of Claim 20 or 21.   A paint, a purification device, or a filter containing the photocatalyst according to claim 20 or 21. It is a manufacturing method of the glass ceramics in any one of Claim 1 to 17,
A melting step of mixing raw materials to obtain a melt;
A cooling step of cooling the melt to obtain glass;
A reheating step of raising the temperature of the glass to a crystallization temperature region;
A crystallization step of maintaining the temperature within the crystallization temperature region to produce crystals;
A re-cooling step of obtaining a crystal-dispersed glass by lowering the temperature outside the crystallization temperature region.   The method for producing glass ceramics according to claim 27, wherein the crystallization temperature region is 450 ° C or higher and 1200 ° C or lower.   The method for producing glass ceramics according to claim 27, further comprising an etching step of performing dry etching and / or wet etching on the glass ceramics.

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