JP2009263180A - Glass ceramic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass ceramic which has no problem about the durability, is formed into a desired shape by a relatively easy method and has high photocatalytic activity. <P>SOLUTION: The glass ceramic contains at least one kind selected from TiO<SB>2</SB>, Ca<SB>2</SB>Ti<SB>5</SB>O<SB>12</SB>, Ca<SB>2</SB>Ti<SB>2</SB>O<SB>6</SB>, CaTiSiO<SB>5</SB>and their solid solutions as a crystal phase having activity as a photocatalyst, has a glass phase containing an SiO<SB>2</SB>component, wherein a TiO<SB>2</SB>component of 5-60 mol% and an SiO<SB>2</SB>component of 15-80 mol% are contained expressed in terms of oxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glass ceramic having a photocatalytic function and a method for producing the same, and more particularly to a glass ceramic having a crystal having a photocatalytic function deposited thereon and a method for producing the same.

A photocatalyst causes an oxidation or reduction reaction in the vicinity of its surface by involving electrons and holes generated by irradiating a semiconductor having a photocatalytic function with light having energy higher than its band gap energy. In particular, surface treatment using titania (TiO ₂ ) crystals having high catalytic activity is generally well known.

  For example, in order to manufacture a member having a photocatalytic action, a photocatalytic coating agent containing titanium oxide as a photocatalyst to be applied to the surface is disclosed (for example, Patent Document 1). In this way, photocatalytic action can be added only to the surface while maintaining the mechanical properties of the substrate, which is very convenient. However, in application and coating, the durability of the coating film and the coating layer is not sufficient, and peeling becomes a problem depending on the use situation.

  On the other hand, as an example of putting a photocatalytic material in the bulk, as a photocatalyst (apatite having titanium as a metal atom necessary for having photocatalytic activity (photocatalytic titanium apatite)) with respect to polypropylene resin, There is disclosed a photocatalyst composite material obtained by adding 30% by mass of calcium / titanium hydroxyapatite, kneading to form a ball shape (spherical shape) having a diameter of 3 cm, passing through a breaker, and pulverizing to about 5 mm square with a sieve (for example, Patent Document 2). However, this is only a composite material of about 5 mm square in which calcium / titanium hydroxyapatite is bonded using polypropylene resin as a binder. Therefore, the application field is limited to a field such as catalyst particles charged into the reaction vessel.

In addition, by weight percentage (%), SiO ₂ , Al ₂ O ₃ , CaO, MgO, B ₂ O ₃ , ZrO ₂ , and TiO ₂ are selected in a predetermined composition ratio, and these are melted and vitrified by conventional means. A glass for photocatalysts is disclosed (for example, Patent Document 3). However, it is difficult to say that titanium ions do not have a crystal structure as will be described later, and are only bonded to oxygen in glass and exist in an amorphous form, thus exhibiting high photocatalytic properties.

Furthermore, through a step of melting a mixture containing titania and a glass-forming oxide to obtain a phase separation melt, through a step of vitrifying the phase separation melt to obtain a phase separation glass, in the phase separation glass A method for producing a photocatalyst composition for crystallizing titania as anatase titania is disclosed (for example, Patent Document 4). However, this method is composed of a two-component system of TiO ₂ —SiO ₂ , melts at a high temperature of about 1780 ° C. or higher, and requires rapid cooling with a twin roller. It is difficult to form it into a shape.
JP 2008-81712 A JP 2008-36465 A Japanese Patent Laid-Open No. 9-315837 JP 2001-113177 A

  As described above, when applying or coating on the surface of the substrate, the basic properties of the substrate can be selected according to the purpose of use, but the coating film or the like attached to the surface may be peeled off. In addition, since organic binders are often used for film formation, there is a problem that clouding and white blurring occur due to changes over time due to ultraviolet rays, acid rain, and the like. On the other hand, there is an integrated catalyst material in which a titania crystal and a resin are combined, but as described above, the resin is decomposed by irradiation with ultraviolet rays, and good durability cannot be obtained.

  In view of such circumstances, an object of the present invention is to provide a glass ceramic that has no problem of durability due to peeling or the like, can be molded into a desired shape by a relatively easy method, and has high photocatalytic activity. More specifically, the present invention provides a glass ceramic comprising an inorganic compound composition having a relatively high activity as a photocatalyst as a crystal phase.

  More specifically, the following glass ceramics and methods for producing the same are provided.

(1) Glass ceramics containing at least one selected from TiO ₂ , Ca ₂ Ti ₅ O ₁₂ , Ca ₂ Ti ₂ O ₆ , CaTiSiO ₅ or a solid solution thereof as a crystalline phase.

There are generally three types of crystal forms of titanium oxide (TiO ₂ ): anatase, rutile, and brookite. As the photocatalyst, Anatase is most preferable. Anatase (tetragonal I41 / amd, low temperature stable) is generally produced by wet hydrolysis of titanium oxide sulfate (titanyl sulfate), titanium sulfate, tetraalkoxy titanium, etc., and used as a photocatalyst. Rutile (tetragonal P42 / mmm, stable at high temperature) is produced by wet hydrolysis of titanium tetrachloride, high temperature treatment of Anatase at 700 ° C. or higher, etc., and is used for paints and pigments. Compared to these, there are few studies on the synthesis and use of Brookite (Pbca, plate titanium stone). There is no established theory about the stability of these crystal types, and there are reports that the stability varies depending on the crystal particle size. For example, there is a report that anatase is more stable than Rutile at a particle size of 14 nm or less effective as a photocatalyst. The theoretical density calculated from the crystal form is as follows.
Rutile (4.25 g / cm ³ )> Brookite (4.12 g / cm ³ )> Anatase (3.893 g / cm ³ )

TiO ₂ is preferably used because it is chemically stable and non-toxic. TiO ₂ preferably has an anatase type crystal structure exhibiting high photocatalytic properties, and may be a rutile type or a brookite type depending on conditions. The crystal structure of TiO ₂ can be measured by an X-ray diffraction method (XRD measurement method).

In addition, calcium titanate Ca ₂ Ti ₅ O ₁₂ and Ca ₂ Ti ₂ O ₆ have a simple cubic crystal in the former and a defective pyrochlore structure in the latter, and can generally be used as a high dielectric. In addition, calcium titanium silicate (CaTiSiO ₅ ) is generally called sphene, is a monoclinic crystal with a high refractive index, and is considered to exhibit photocatalytic properties similar to TiO 2. It is a useful crystal.

  These band gap energies are preferably in the range of 2.0 eV to 4.0 eV. Moreover, band gap energy can be adjusted by using a solid solution. Controlling the band gap energy contributes to an improvement in response to light.

A solid solution means a state in which two or more kinds of metal solids or non-metal solids are dissolved in each other at an atomic level to form a uniform solid phase as a whole, and may be called a mixed crystal. Depending on how the solute atoms permeate, there are interstitial solid solutions in which elements smaller than the gaps in the crystal lattice enter, and substitutional solid solutions in which they replace the parent phase atoms. As a solid solution of TiO ₂ , a solute substance is not fixed, and the type of TiO ₂ is not limited. For example, Ti _1-x Zr _x O ₂ can be mentioned. _{Further, Ca 2 Ti 5 O 12,} Ca 2 Ti 2 O 6, as a solid solution of CaTiSiO _5, for example, _{(Ca 1-x Sr x)} 2 Ti 5 O 12, (Ca 1-x Sr x) 2 Ti 2 O ₆ , (Ca _1-x Sr _x ) TiSiO _{5 and the} like.

Other materials that exhibit photocatalytic properties include zinc oxide (ZnO), tin oxide (SnO ₂ ), strontium titanate (SrTiO ₃ ), tungsten oxide (WO ₃ ), bismuth oxide (Bi ₂ O ₃ ), and iron oxide. (Fe ₂ O ₃ ) can be included, and one or two or more can be selected and mixed from these.

  Glass ceramics is a material obtained by precipitating a crystalline phase in a glass phase by heat-treating the glass, not only a material composed of a glass phase and a crystalline phase, but also a material in which the glass phase is all crystalline. That is, a material having a crystal amount (crystallinity) of 100 wt% in the material may be included. Engineering ceramics and ceramic sintered bodies obtained from commonly used powders have a small amount of liquid phase during sintering, and are difficult to become pore-free fully sintered bodies. Therefore, such pores (for example, porosity) can be distinguished from the glass ceramic here. In particular, with regard to ionic conduction, in the case of ceramics, the movement of ions is limited by the presence of vacancies and grain boundaries, so that the overall conductivity is generally low. Glass ceramics can suppress a decrease in conductivity between crystals by controlling the crystallization process, and can maintain the same conductivity as crystal grains. On the other hand, a single crystal can be cited as a material having almost no vacancies or crystal grain boundaries that impede ion conduction, but the production of a single crystal is much more difficult and costly than the production of glass ceramics.

(2) The glass ceramic according to (1) above, which has a glass phase, and the glass phase contains at least a SiO ₂ component.

(3) The glass according to any one of (1) and (2) above, which contains 5 to 60% of TiO ₂ component and 15 to 80% of SiO ₂ component in mol% based on oxide. Ceramics.

SiO ₂ is a glass-forming oxide, and is an important component for obtaining glass. If the amount is less than 15%, there is a high possibility that a glass cannot be obtained. Therefore, the preferable content is 15% or more, the more preferable amount is 25% or more, and the most preferable amount is 30% or more. On the other hand, if it exceeds 80%, the melting temperature of the glass tends to rise remarkably, so the content of the SiO ₂ component is preferably 80% or less, more preferably 70% or less, and most preferably 60% or less.

The TiO ₂ component is a very useful component in the present invention, and if the amount is 5% or less, it is difficult to precipitate as a crystalline phase, so that there is a high possibility that the catalyst characteristics are not exhibited. Accordingly, the TiO ₂ component is preferably contained in an amount of 5% or more, more preferably 10% or more, and most preferably 15% or more. On the other hand, when the content of TiO ₂ exceeds 60%, the melting point becomes high and further vitrification becomes difficult. Accordingly, the content of the TiO ₂ component is preferably 60% or less, more preferably 55% or less, and most preferably 50% or less.

TiO ₂ component and SiO ₂ component can be contained in the glass ceramic by melting a mixture of TiO ₂ powder and SiO ₂ powder as a raw material, TiO ₂ and SiO ₂ precursors, the gas phase It is also possible to use a liquid phase method such as a sol-gel method such as an alkoxide, a coprecipitation method, or a hydrothermal method.

(4) The glass ceramic according to any one of (1) to (3) above, further containing 1 to 60 mol% of an alkali metal oxide component and / or an alkaline earth metal oxide component.

The alkali metal oxide component and / or the alkaline earth metal oxide component is effective in lowering the melting point of the glass and further improving the meltability and stability of the glass. When the total content of these oxides is less than 1%, the above effect is hardly obtained, so the total content is preferably 1% or more, and more preferably 10% or more. However, if it exceeds 60%, glass cannot be obtained. Therefore, the total amount of these oxides is preferably 60% or less, more preferably 50% or less, and most preferably 40% or less. The alkali metal oxide component is one or more selected from Li ₂ O, Na ₂ O, K ₂ O, and Cs ₂ O, and the alkaline earth metal oxide component is one or more selected from MgO, SrO, CaO, and BaO. is there.

(5) The glass ceramic as described in (4) above, wherein the alkaline earth metal oxide component contains CaO.

Since the CaO component is effective for promoting the precipitation of the TiO ₂ crystal phase in addition to the above-described effects, it is preferably contained. Further, since the CaO component is also a constituent component of the Ca ₂ Ti ₅ O ₁₂ , Ca ₂ Ti ₂ O ₆ , and CaTiSiO ₅ crystal phases, it is indispensable when these crystal phases are precipitated.

(6) In addition, 0-60% of B ₂ O ₃ component in mole percent on the oxide basis and / or,
GeO ₂ component 0-10% and / or
0-22% of al ₂ O ₃ component and / or,
0-10% of P ₂ O ₅ component and / or,
0 to 60% of ZnO component and / or
0-20% and / or ZrO ₂ component
SnO component 0-10% and / or
0-20% of Bi ₂ O ₃ component + TeO ₂ component and / or,
Nb ₂ O ₅ component + Ta ₂ O ₅ component + WO ₃ component 0-30% and / or
Ln ₂ O ₃ component 0-30% (Ln is one or more selected from Y, Ce, La, Nd, Gd, Dy, Yb) and / or
MO _y component is 0 to 10% (M is one or more selected from V, Cr, Mn, Fe, Co, Ni, Cu; y is a number obtained by dividing the valence of M by 2) and / or ,
0 to 5% of As ₂ O ₃ component + Sb ₂ O ₃ component
The glass ceramic according to any one of (1) to (5) above, comprising:

The B ₂ O ₃ component can also be a glass-forming oxide and can contribute to glass meltability and stability. Therefore, it can be a component that supplements the SiO ₂ component, but if it is added too much, the target crystal phase is difficult to precipitate. From such a viewpoint, the B ₂ O ₃ component can be included as necessary, but is preferably 60% or less, more preferably 40% or less, and still more preferably in terms of mol% based on the oxide. 20% or less.

GeO ₂ component, since the same function as the SiO ₂ component, it is possible to replace some or all of the SiO _2, since it is more expensive than SiO _2, the upper limit is 10% or less It is preferably 5% or less, more preferably 3% or less. The total amount of the GeO ₂ component and the SiO ₂ component is preferably 80% or less, more preferably 70% or less, and most preferably 60% or less.

The Al ₂ O ₃ component is effective in improving the stability of the glass, and further has a function of promoting the precipitation of the target crystal phase. However, if the amount is too large, it tends to hinder the precipitation of the target crystal phase, so the upper limit is preferably 22% or less, more preferably 20% or less, and more preferably 18% or less. Is most preferred. Moreover, since the molar ratio of Al ₂ O ₃ / SiO ₂ has a great influence on the precipitation of the crystal phase, if the ratio is too large, it becomes difficult to precipitate the target crystal phase. The ratio is preferably 0.65 or less, more preferably 0.6 or less, and most preferably 0.5 or less.

The P ₂ O ₅ component is a component that is effective for precipitation of the target crystal phase. However, if the amount is too large, the stability of the glass tends to decrease, so the upper limit is preferably 10% or less, more preferably 5% or less, and most preferably 1% or less. preferable.

  The ZnO component is basically a component that has the same effect as the alkaline earth oxide described above, and is further effective in improving the photocatalytic properties. However, if the amount is too large, the stability of the glass tends to decrease, so the upper limit is preferably 60% or less, more preferably 55% or less, and most preferably 50% or less. preferable.

The ZrO ₂ component is effective in precipitating the target crystal phase, and further dissolves in the crystal phase and contributes to the improvement of the photocatalytic properties. However, if the amount is too large, the stability of the glass tends to decrease, so the upper limit is preferably 20% or less, more preferably 15% or less, and most preferably 8% or less. preferable.

SnO is a component having a function similar to that of the above-described ZrO ₂ and further effective in preventing reduction of Ti ⁴⁺ ions. However, if the amount is too large, the stability of the glass tends to decrease, so the upper limit is preferably 10% or less, more preferably 5% or less, and most preferably 3% or less. preferable.

Bi ₂ O ₃ component and TeO ₂ component are components that are effective in improving the meltability and stability of the glass, but if the amount is too large, the stability of the glass tends to decrease, so the sum of both components The upper limit of the amount is preferably 20% or less, more preferably 15% or less, and most preferably 10% or less.

Nb ₂ O ₅ component and / or Ta ₂ O ₅ component and / or WO ₃ component are effective in improving the meltability and stability of glass, and further solid-dissolved in the crystal phase and contribute to the improvement of photocatalytic properties. However, if the amount is too large, the stability of the glass is remarkably lowered, so the upper limit of the total amount of these components is preferably 30% or less, more preferably 20% or less. % Or less is most preferable.

The Ln ₂ O ₃ component (Ln is one or more selected from Y, Ce, La, Nd, Gd, Dy, and Yb) is effective in improving the meltability and stability of the glass, and is further solidified in the crystal phase. It is a component that contributes to the improvement of the photocatalytic properties, but if the amount is too large, the stability of the glass tends to be remarkably lowered, so the upper limit of the total amount of these components is preferably 30% or less, It is more preferably 20% or less, and most preferably 10% or less.

MO component (M is one or more selected from V, Cr, Mn, Fe, Co, Ni, Cu. _Y is a number obtained by dividing the valence of M by 2). This component is effective in improving the photocatalytic properties, and further absorbs a part of visible light, so that it is a component that can give a desired appearance color according to the design. However, if the addition amount is too large, the stability of the glass is deteriorated and it is difficult to adjust the color of the appearance. Therefore, the upper limit of the total amount of these components is preferably 10% or less, and preferably 5% or less. More preferably, it is most preferably 3% or less.

The As ₂ O ₃ component and the Sb ₂ O ₃ component are components that can be added for defoaming during glass melting, but the total amount of these components is sufficiently effective at 5% or less. It is preferably 3% or less, and most preferably 1% or less.

  In addition, it is desirable that the glass ceramic composition does not contain as much components as possible such as Pb, Cd, and Hg that may cause harm to the environment and the human body.

(7) The glass ceramic according to any one of (1) to (6) above, wherein the crystal phase has an average diameter of 5 nm to 50 μm when approximated to a sphere.

  It is possible to control the size of the precipitated crystal phase by controlling the heat treatment conditions. However, in order to extract effective photocatalytic properties, the crystal size is preferably in the range of 5 nm to 50 μm, and 5 nm to 40 μm. Is more preferable, and the range of 5 nm to 30 μm is most preferable.

(8) The glass ceramic according to any one of (1) to (7) above, wherein the amount of the crystal phase is in the range of 1 to 95% by volume ratio.

  The amount of crystal phase precipitated from the glass can be controlled by controlling the heat treatment conditions. If the amount of the crystal phase is large, the photocatalytic function tends to be high, but the mechanical strength of the entire glass ceramic may be lowered. Therefore, the amount of the crystal phase should be in the range of 95% or less by volume ratio. Is preferable, it is more preferable to set it as the range of 93% or less, and it is most preferable to set it as 90% or less. On the other hand, if the amount of the crystal phase is small, effective photocatalytic properties cannot be obtained. Therefore, the amount of the crystal phase is preferably 1% or more by volume, more preferably 3% or more, and most preferably 5% or more. preferable.

(9) The glass ceramic according to any one of (1) to (8), which responds to light from ultraviolet rays to visible light and has photocatalytic properties.

  Ultraviolet light means invisible electromagnetic waves having a wavelength shorter than visible light and longer than soft X-rays, and can mean electromagnetic waves having a wavelength of 10 to 400 nm, for example. Visible light means an electromagnetic wave having a wavelength that can be seen by human eyes among electromagnetic waves. For example, the range is approximately 400 nm to 700 nm.

The TiO ₂ crystal shows a high catalytic effect for ultraviolet irradiation, but the response to visible light is weaker than that of ultraviolet light. In the present invention, as described later, the band gap energy of TiO ₂ can be reduced by dissolving other ions in the TiO ₂ crystal phase in the course of heat treatment, which is also effective for visible light. It became possible to obtain glass ceramics exhibiting a response effect. Moreover, the glass ceramic of this invention is applicable to a wide use by such an effect.

(10) A method for producing the glass ceramic according to any one of (1) to (9) above, wherein a glass is produced by melting a raw material composition mixture, and further subjected to heat treatment at 500 ° C to 1200 ° C. A method for producing a glass ceramic, wherein the crystal phase is precipitated.

The crystal phase is formed when atoms have a certain degree of freedom of movement (for example, mobility), and the mobility increases as the temperature increases. On the other hand, the TiO ₂ component is likely to form a stable rutile phase at a high temperature, and in order to form an anatase phase generally preferred as a photocatalyst, a heat treatment at a low temperature is preferable, but if the heat treatment temperature is too low, The crystal phase is difficult to precipitate. Therefore, the lower limit of the heat treatment is preferably 500 ° C. or higher, more preferably 550 ° C. or higher, and still more preferably 600 ° C. or higher. Moreover, as an upper limit of the said heat processing, 1200 degrees C or less is preferable, More preferably, it is 1100 degrees C or less, More preferably, it is 1000 degrees C or less.

(11) A method for producing the glass ceramic according to any one of (1) to (9) above, wherein a liquid phase is produced at least partially by maintaining the raw material composition mixture at a temperature of 800 ° C. or higher. Then, the glass ceramics production method characterized by solidifying by cooling after that.

  Here, a liquid phase may be produced | generated from at least 1 or more types of raw material composition, and the fall of the liquid phase production temperature by adding 2 or more types of compounds can also be considered. Accordingly, the temperature to be maintained is preferably changed as appropriate depending on the type and amount of the composition to be mixed, but is generally preferably 800 ° C or higher, more preferably 1200 ° C or higher, and further preferably 1400 ° C or higher. Once the liquid phase is generated, the contact area between the compositions or the degree of reaction is considered to be high, so the temperature can be partially increased.

(12) The method for producing a glass ceramic according to any one of (10) and (11), wherein the surface is further etched with an acid or an alkali.

  By etching with acid or alkali, the glass around the crystal phase is removed, and the specific surface area of the crystal phase exposed on the surface is increased, so that the photocatalytic properties are improved. The glass phase is typically considered to have a large amount of silicon oxide component, and etching by acid treatment is effective. In particular, etching with hydrofluoric acid, hydrogen fluoride gas or the like is preferable.

(13) A photocatalytic functional molded body comprising the glass ceramic according to any one of (1) to (10).

(14) The photocatalytic functional molded article according to (13) above, which is a fiber.

  The glass ceramic according to the present invention is relatively easy to mold and can be a desired structure according to the application. Furthermore, glass ceramics can be incorporated into the cast part by casting or the like. Moreover, the glass phase of glass ceramics generally has a high viscosity when softened, and fiber forming is easy. In view of the fact that the fiber generally has a large specific surface area and a photocatalytic reaction mainly occurs on the surface, the photocatalytic function can be enhanced by using a fiber. In addition, various products can be made by using the fiber and making paper.

  As described above, there is no fear of peeling of the photocatalytic film on the surface of the substrate. Further, it is possible to provide a glass ceramic having sufficient size and mechanical properties and capable of contacting with a compound whose catalytic activity point should react. It is also possible to obtain a higher catalytic function by precipitating crystals preferable as a photocatalyst.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following description is made for explaining the embodiments of the present invention, and the present invention is not limited to the embodiments. Needless to say, various modifications can be made without departing from the scope of the present invention.

[Example 1]
Commercially available SiO ₂ , TiO ₂ , Al (OH) ₃ , and CaCO ₃ were used as raw materials for Example 1. Further, these raw materials were weighed so as to have a composition of SiO ₂ = 38.5, TiO ₂ = 25, Al ₂ O ₃ = 12.5, and CaO = 24 in mol%, and mixed uniformly in the atmosphere. And melted at 1450 ° C. for 2 hours. Then, the glass solution which became uniform was poured into the metal mold | die, and the bulk glass was produced. The glass was annealed at 650 ° C. for 2 hours to remove heat stress. The glass thus obtained was cut into a predetermined shape and heat treated at 800 ° C. for 4 hours. Identification of crystals by XRD revealed that anatase TiO ₂ and rutile TiO ₂ crystal phases were precipitated simultaneously as shown in FIG. From the width of the diffraction peak, the equation D = λ / (β · cos θ) (λ is the wavelength of the X-ray, 1.54 mm in this apparatus. Β is the spread of the diffraction line due to the size of the crystallite, The average crystal size estimated by θ is the diffraction angle) was around 10 nm.

[Examples 2 to 9 and Comparative Example]
Samples of Examples 2 to 9 and Comparative Example 1 were produced by a method similar to that of Example 1. The composition of each sample is shown in Table 1 together with the experimental results (in the table, ◎ indicates particularly good, x indicates not so good. The same applies to the following table). It was confirmed that the TiO ₂ crystal phase was precipitated in Examples 2 to 7, the Ca ₂ Ti ₂ O ₆ crystal phase was precipitated in Example 8, and the Ca ₂ Ti ₅ O ₁₂ and CaTiSiO ₅ crystals were precipitated in Example 9. On the other hand, in Comparative Example 1, the above-described precipitation of the crystal phase was not recognized, and the crystal phase could not be identified.

[Example 10]
Commercially available SiO ₂ , TiO ₂ , Al (OH) ₃ , CaCO ₃ , and MgO were used as raw materials. These were weighed so as to have a composition of mol% SiO ₂ = 45, TiO ₂ = 25, Al ₂ O ₃ = 7.5, CaO = 17.5, MgO = 5 (see Table 2) and mixed uniformly. Then, it was melted at 1550 ° C. for 2 hours in the atmosphere. Thereafter, the homogenized solution was lowered to 1500 ° C. and poured into a mold to produce glass ceramics. The glass ceramic was annealed at 750 ° C. for 2 hours to remove heat stress. As a result of identifying the crystal by XRD of the glass ceramic thus obtained, it was found that a rutile TiO ₂ crystal phase was simultaneously precipitated. Table 2 shows the results of Example 10. Here, for Examples 1 to 10 and Comparative Example, the ratio of Al ₂ O ₃ / SiO ₂ is 0.325, 0.312, 0.325, 0.457, 0.455, 0.325, 0.325, 0.325, 0.000, 0.167, and 0.672, respectively. there were.

[Photocatalyst evaluation]
The photocatalytic properties were evaluated by Photocatalyst Performance Evaluation Method I established by the Photocatalyst Product Technical Council. That is, the sample of the present invention was evaluated by a method for evaluating the performance of the photocatalyst by decolorization of the dye. When a methylene blue solution was dropped onto the surface of the polished example sample and the color after irradiation with ultraviolet rays was observed, decoloration was observed in all cases. This showed that the sample of the present invention exhibited photocatalytic properties. In addition, decoloration was not confirmed about the comparative example.

[Application of photocatalytic glass ceramics]
As described above, glassy glass ceramics can be obtained by simple melting and cooling, and preferable photocatalytic properties can be obtained by appropriately heat-treating it. Here, glass is poured into the mold, but blow molding is also possible. It will be understood by those skilled in the art that the fiber can be easily extended. And the mechanical characteristic and chemical characteristic of each molded object are realizable by selecting a preferable composition suitably in the range of the composition of this invention.

  As described above, the glass ceramics of the present invention can provide a photocatalyst molded article that has favorable mechanical properties and does not cause deterioration of the photocatalytic function due to peeling or the like.

2 is an X-ray diffraction pattern of Sample 1.

Claims (14)

Glass ceramics containing at least one selected from TiO ₂ , Ca ₂ Ti ₅ O ₁₂ , Ca ₂ Ti ₂ O ₆ , CaTiSiO ₅ or a solid solution thereof as a crystal phase. The glass ceramic according to claim 1, comprising a glass phase, wherein the glass phase contains at least a SiO ₂ component. 3. The glass ceramic according to claim 1, wherein the glass ceramic contains 5 to 60% of a TiO ₂ component and 15 to 80% of a SiO ₂ component in mol% based on an oxide.   The glass ceramic according to any one of claims 1 to 3, further comprising 1 to 60 mol% of an alkali metal oxide component and / or an alkaline earth metal oxide component.   The glass ceramic according to claim 4, wherein the alkaline earth metal oxide component contains CaO. Furthermore, 0 to 60% of B ₂ O ₃ component and / or
GeO ₂ component 0-10% and / or
0-22% of al ₂ O ₃ component and / or,
0-10% of P ₂ O ₅ component and / or,
0 to 60% of ZnO component and / or
0-20% and / or ZrO ₂ component
SnO component 0-10% and / or
0-20% of Bi ₂ O ₃ component + TeO ₂ component and / or,
Nb ₂ O ₅ component + Ta ₂ O ₅ component + WO ₃ component 0-30% and / or
Ln ₂ O ₃ component 0-30% (Ln is one or more selected from Y, Ce, La, Nd, Gd, Dy, Yb) and / or
MO _y component is 0 to 10% (M is one or more selected from V, Cr, Mn, Fe, Co, Ni, Cu; y is a number obtained by dividing the valence of M by 2) and / or ,
0 to 5% of As ₂ O ₃ component + Sb ₂ O ₃ component
The glass ceramic according to claim 1, comprising:   The glass ceramic according to any one of claims 1 to 6, wherein the crystal phase has an average diameter of 5 nm to 50 µm when approximated to a sphere.   The glass ceramic according to any one of claims 1 to 7, wherein the amount of the crystal phase is in a range of 1 to 95% by volume ratio.   The glass ceramic according to any one of claims 1 to 8, which has photocatalytic properties in response to light from ultraviolet rays to visible light.   A method for producing the glass ceramic according to any one of claims 1 to 9, wherein a glass is produced by melting a raw material composition mixture, and further subjected to heat treatment at 500 ° C to 1200 ° C to precipitate the crystalline phase. A method for producing glass ceramics, comprising:   A method for producing the glass ceramic according to any one of claims 1 to 9, wherein a liquid phase is produced at least in part by maintaining the raw material composition mixture at a temperature of 800 ° C or higher, and then cooled. A method for producing glass ceramics, characterized by solidifying.   Furthermore, the surface is etched with an acid or an alkali, The manufacturing method of the glass ceramics in any one of Claim 10 or 11 characterized by the above-mentioned.   The photocatalyst functional molded object containing the glass ceramic in any one of Claim 1 to 10.   It is a fiber, The photocatalyst functional molded object of Claim 13 characterized by the above-mentioned.

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