JP2013023400A - Method for producing wadalite compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a wadalite compound, with which a film-shaped wadalite compound is formed on a substrate without being so much restrained by heat resistance of the substrate.SOLUTION: The method for producing a wadalite compound represented by compositional formula of CaAlSiOCl(where x=0 to 4) includes: (i) a step of preparing an amorphous material A represented by compositional formula of CaAlSiO(where x=0 to 4); and (ii) a step of generating the wadalite compound by treating the material A with chlorine at a temperature below 850°C.

Description

  The present invention relates to a method for producing a wadalite compound.

The wadalite compound has a composition of Ca ₁₂ Al _(14-x) Si _x O ₃₂ Cl _{(x + 2)} (x = 0 to 4), and is a three-dimensionally connected void having an inner diameter of about 0.4 nm ( (Cage) has a characteristic crystal structure. The skeleton constituting this cage is positively charged and forms 12 cages per unit cell. A part of the cage is occupied by chlorine ions in order to satisfy the electrical neutrality condition of the crystal (Non-Patent Document 1).

The wadalite compound is prepared by mixing CaO (calcium oxide), Al ₂ O ₃ (alumina), and SiO ₂ (silica) so as to have a stoichiometric composition, and then adding an excess amount of CaCl ₂ (calcium chloride to this mixed raw material. ) And the resulting mixture is heat-treated at 850 ° C. for 72 hours (Non-patent Document 2).

J. et al. Jeevaratnam, F.A. P. Glasser, and L.L. S. D. Glasser, J. et al. Am. Ceram. Soc. , Vol. 47, no. 2, p105-p106 (1964) Qui Ling Feng, Frederic P.M. Glasser, R.A. Alan-Howie, and Eric E. et al. Lachowski, Acta Cryst. , C44, p589-p592 (1988)

As described above, the wadalite compound is prepared by adding calcium chloride to CaO, Al ₂ O ₃ , and SiO ₂ prepared to have a stoichiometric composition, and heat-treating the resulting mixture at 850 ° C. for 72 hours. Manufactured by.

  However, such a conventional manufacturing method has the following problems.

  For example, when forming a film-like wadalite compound on a substrate, it is necessary to heat the substrate to a temperature of 850 ° C. or higher in the conventional manufacturing method. For this reason, in the conventional manufacturing method, the kind of board | substrate to be used is restricted and the problem that only a heat resistant board | substrate can be used may arise. For example, when glass is selected as the substrate material, the glass substrate may be softened or deformed at such a processing temperature, and an appropriate film formation may not be performed.

  The present invention has been made in view of such a background, and in the present invention, a wadalite compound capable of forming a film-like wadalite compound on a substrate without being largely restricted by the heat resistance of the substrate. It aims at providing the manufacturing method of.

In the present invention, a method for producing a wadalite compound represented by a composition of Ca ₁₂ Al _(14-x) Si _x O ₃₂ Cl _{(x + 2)} (where x = 0 to 4),
(I) a step of preparing an amorphous material A represented by a composition of Ca ₁₂ Al _(14-x) Si _x O _{(33 + x / 2)} (where x = 0 to 4);
(Ii) chlorinating the material A at a temperature of less than 850 ° C. to produce a wadalite compound;
A manufacturing method is provided.

Here, in the production method according to the present invention, the step (ii) includes:
(A) adding a metal chloride to the material A and heat-treating the resulting mixture at a temperature of less than 850 ° C., or (b) reducing the material A to less than 850 ° C. in an atmosphere containing a chlorine-containing gas. A step of heat treatment at a temperature of

In this case,
The metal chloride may include calcium chloride and / or potassium chloride, or the chlorine-containing gas may include hydrogen chloride gas and / or chlorine gas.

  Moreover, in the manufacturing method by this invention, the process of said (ii) may be implemented at the temperature of 620 degreeC or more.

  In the production method according to the present invention, in the step (i), the raw material obtained by blending calcium oxide, alumina, and silica at a predetermined ratio was held and melted at a temperature of 1450 ° C to 1800 ° C. Thereafter, a step of quenching may be included.

  In the production method according to the present invention, the step (ii) may include a step of chlorinating the material A on a substrate, and a film-like wadalite compound may be formed on the substrate.

  In this case, the substrate may be a glass substrate.

In the present application, the Wadaraito _{compound, Ca 12 Al (14-x} ) Si x O 32 Cl (x + 2) ( provided that x = 0 to 4) having a crystal, and isomorphic with equivalent crystal structure as that Means a compound.

Therefore, the wadalite compound in the present application maintains a Ca ₁₂ Al _(14-x) Si _x O ₃₂ Cl _{(x + 2)} (where x = 0 to 4) crystal lattice skeleton and a cage structure formed by the skeleton. Ca ₁₂ Al _(14-x) Si _x O ₃₂ Cl _{(x + 2)} (where x = 0 to 4) a compound in which a part of atoms constituting the crystal skeleton is substituted with other atoms, and cage An isomorphous compound in which some of the chlorine ions therein are replaced with oxygen ions is included.

  The present invention can provide a method for producing a wadalite compound that can form a film-like wadalite compound on a substrate without being significantly restricted by the heat resistance of the substrate.

It is a flowchart of an example of the manufacturing method of the wadalite compound by this invention. 2 is an X-ray diffraction pattern of powder a in Example 1. FIG. 2 is an X-ray diffraction pattern of white powder in Example 1. FIG. 3 is an X-ray diffraction pattern of a powder obtained after heat treatment in Example 2. FIG. 4 is an X-ray diffraction pattern of a film-like substance in Example 3. FIG.

  Hereinafter, the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic flow chart of an example of a method for producing a wadalite compound according to the present invention.

As shown in FIG. 1, the method for producing a wadalite compound according to the present invention comprises:
A step of preparing an amorphous material A represented by a composition of Ca ₁₂ Al _(14-x) Si _x O _{(33 + x / 2)} (where x = 0 to 4) (step S110);
A step (step S120) of producing a wadalite compound by chlorinating the material A at a temperature of less than 850 ° C .;
Have

  In the present invention, unlike the conventional method for producing a wadalite compound as described above, the wadalite compound is produced by “chlorinating” the material A at a relatively low temperature (temperature less than 850 ° C.).

  Here, “chlorine treatment” means a general term for treatment methods capable of introducing chlorine ions into the skeleton constituting the cage of the material A. For example, “chlorination” includes a method of mixing the material A and a metal chloride, heat-treating the obtained mixture, and a method of heat-treating the material A in an atmosphere containing a chlorine-containing gas.

  In such a method according to the present invention, when forming a film-shaped wadalite compound on a substrate, the necessity of being constrained by the heat resistance of the substrate is reduced, and the types of substrates that can be used are increased. For example, in the present invention, a wadalite compound film can be placed on a versatile substrate such as a glass substrate.

  Hereinafter, each process shown in FIG. 1 will be described in detail.

(Process S110)
First, amorphous Ca ₁₂ Al _(14-x) Si _x O _{(33 + x / 2)} (where x = 0 to 4) (hereinafter simply referred to as “material A”) is prepared.

  The method for preparing the material A is not particularly limited, and the material A may be prepared by any general method.

  For example, the material A is rapidly cooled after a raw material obtained by preparing a raw material powder containing calcium oxide powder, alumina powder, and silica powder at a predetermined ratio is held at a temperature of 1450 ° C. to 1800 ° C. and melted. Can be prepared.

In this case, for example, the holding temperature may be in the range of 1500 ° C to 1700 ° C. Moreover, the temperature-fall rate in the case of a rapid cooling process may be the range of 10 < ² > C / min-10 < ⁵ > C / min, for example. Preferably, cooling is performed from 1450 ° C. to 500 ° C. at 10 ² ° C./second to 10 ⁵ ° C./second.

  The processing time at the holding temperature may be in the range of 10 minutes to 3 hours.

Here, the material A used in the present invention needs to be amorphous. This is because when a mixture of crystalline compounds is used as a material, it is difficult to obtain a wadalite compound at a low temperature and in a high yield. For example, when the material A is not made amorphous and a mixture of CaO crystal, Al ₂ O ₃ crystal and SiO ₂ crystal is used as the material, the wadalite compound cannot be obtained as a simple substance but becomes a mixture of crystalline compounds.

  In a typical case, the value of x in the general formula of material A is about 3.4. However, the value of x can be suitably selected in the range of 0-4.

  The raw material has a ratio of calcium (Ca), aluminum (Al) and silicon (Si) of 12: 14: 0 to 12: 10: 4 in a molar ratio of Ca: Al: Si, and with respect to Ca. , Al and Si are mixed so that the molar ratio of Ca: (Al + Si) is 12:14. Ca: Al: Si (molar ratio) is preferably 12: 12: 2 to 12: 10: 4.

  In addition, the compound used as a raw material is not particularly limited as long as the ratio is maintained.

  The raw material may be, for example, a mixture containing a calcium compound and an aluminum compound. The raw material may be, for example, a mixture containing a calcium compound, an aluminum compound, and a silicon compound.

  The raw material may include an aluminosilicate. The raw material may be a mixture of an aluminosilicate and at least one selected from the group consisting of a calcium compound, an aluminum compound and / or a silicon compound.

  Examples of the calcium compound include calcium carbonate, calcium oxide, and calcium hydroxide. Of these, calcium carbonate is preferred.

  Examples of the aluminum compound include aluminum hydroxide, aluminum oxide, and aluminum nitrate. Among these, aluminum oxide is preferable.

  As the silicon compound, silicon oxide is preferable.

  The material A is preferably powdered. In this case, a wadalite compound having a uniform composition can be more easily obtained in the subsequent chlorination process.

  When the material A is powdery, the particle size is not particularly limited. The particle size of the material A may be, for example, in the range of 1 μm to 20 μm (average particle size).

  In a normal case, the powdered material A is prepared by coarsely grinding the material A and further grinding the coarse powder to a fine particle. For the coarsening of the material A, a stamp mill, an automatic mortar, or the like is used. First, the material A is pulverized until the average particle size is about 20 μm. A ball mill, a bead mill, or the like is used to pulverize the coarse powder to the fine powder having the above average particle diameter. For example, when a planetary mill using tungsten carbide balls is used, foreign particles are not mixed in the coarse particles of the material A, and the coarse particles having a particle diameter of 20 μm or less can be obtained. The material A thus obtained can be pulverized into finer particles having an average particle diameter of 10 μm or less using a ball mill or a jet mill. Further, when the material A coarsely pulverized to 20 μm or less is mixed with a solvent and bead pulverized, a finer dispersion solution in which the material A having an average particle diameter of 5 μm or less is dispersed can be produced. For example, zirconium oxide beads can be used for bead grinding. For example, water or an organic solvent can be used as a solvent during the pulverization. As the organic solvent, for example, alcohol or ether can be used.

  As needed, the powdery material A may be pasted, slurried, or sol-gelled.

The method for producing the paste is not particularly limited, and a general method can be used. For example, the paste may be prepared by adding the above prepared powder together with a binder to a solvent and stirring. As the binder, both an organic binder and an inorganic binder can be used. As the organic binder, for example, nitrocellulose, ethylcellulose, polyethylene oxide and the like can be used. As the solvent, butyl acetate, terpineol, alcohol represented by the chemical formula C _n H _{2n + 1} OH (n = 1 to 4), or the like can be used.

  Next, if necessary, the material A prepared as described above is placed on the substrate.

  The material, shape, and dimensions of the substrate are not particularly limited. The substrate may be a glass substrate, for example. Moreover, a metal substrate can be used according to a use. The heat resistant temperature of the metal substrate is preferably 600 ° C. or higher. However, as described above, in the present invention, it is necessary to note that the substrate material can be selected from a wider material range because the restriction on the heat resistance of the substrate is relaxed compared to the conventional manufacturing method.

  The method for placing the material A on the substrate is not particularly limited.

  The material A may be placed on the substrate by, for example, a coating method, a spray method, an impregnation method, or a printing method. For example, the paste containing the material A prepared as described above is applied by screen printing, and the applied film is subjected to a heat treatment to remove the solvent and the binder, whereby the material A is formed into a film on the substrate. Formed. Preferable baking conditions for the coating film are preferably 80 to 850 ° C. in which the organic substances of the components of the slurry are decomposed and the material A is sufficiently fixed to the substrate surface. By performing this heat treatment in air, the solvent and the binder are efficiently removed. As an atmosphere during the heat treatment, an inert gas or a vacuum can be used, and a substrate having low oxidation resistance can be used. The firing time is preferably 10 minutes to 2 hours. Moreover, it is preferable that the thickness of a coating film is 1-50 micrometers.

  Alternatively, the material A may be directly formed in a film shape on the substrate by a film forming technique such as a sputtering method, a PVD method, a CVD method, or an electron beam evaporation method.

(Process S120)
Next, material A is chlorinated, thereby producing a wadalite compound.

  Chlorination is performed at a temperature below 850 ° C. Processing temperature may be implemented in the range of 620 degreeC-800 degreeC, for example. The upper limit of the treatment temperature is more preferably 770 ° C. or lower. If it is less than 620 ° C., a longer chlorination treatment is required. In addition, when the treatment temperature exceeds 770 ° C., the chlorination can be performed in a shorter time. However, when a wadalite compound is produced on a substrate, a heat resistant substrate is required.

The conditions for chlorination are not particularly limited. Chlorine treatment is, for example,
(A) A process of adding a metal chloride to the material A and heat-treating the resulting mixture at a temperature of less than 850 ° C., or (b) a temperature of the material A of less than 850 ° C. in an atmosphere containing a chlorine-containing gas. A heat treatment process may be included.

  In the case of the treatment (a), the metal chloride is not limited to this, but may be, for example, potassium chloride and / or calcium chloride.

  Further, the heat treatment time is not particularly limited. The heat treatment time may be, for example, less than 72 hours, for example, in the range of 1 hour to 10 hours. Moreover, you may implement heat processing in air | atmosphere. The rate of temperature increase and the rate of temperature decrease are not particularly limited, but when a glass substrate is used, it is preferable to set the temperature to 100 ° C./hour to 600 ° C./hour because thermal cracking of the substrate can be avoided.

For example, when the metal chloride is calcium chloride, a wadalite compound can be produced from the material A by heat treatment, for example, through the following reaction (when x = 0):

_{Ca 12 Al 10 Si 4 O 35} + 3CaCl 2
_{→ Ca 12 Al 10 Si 4 O} 32 Cl 6 + 3CaO (1) formula

However, this reaction formula is an example, and a wadalite compound may be generated from the material A through other reactions.

  On the other hand, in the case of the treatment (b), the chlorine-containing gas may be hydrogen chloride gas and / or chlorine gas. The processing atmosphere may further contain hydrogen gas and / or inert gas (for example, nitrogen, argon, and / or helium) and the like.

  Through step S120, material A can be chlorinated to produce a wadalite compound. In particular, when the substrate on which the material A is installed is subjected to chlorination, a film-like wadalite compound can be formed on the substrate.

  Next, examples of the present invention will be described.

(Example 1)
A wadalite compound was produced by the following method.

(Preparation of Material A)
First, CaCO ₃ powder, _Al 2 _{O 3} powder, and the SiO ₂ powder, the molar ratio of 12: 5: 2 and mixed to so, the mixed powder was formulated.

The obtained mixed powder was put into a platinum crucible and held in air at 1650 ° C. for 15 minutes to melt the mixed powder. The melt was rapidly cooled by a double roller method (cooling rate of about 10 ⁴ ° C / min) to obtain a solid having a thickness of about 0.5 mm.

The composition of the solid was Ca ₁₂ Al ₁₀ Si ₄ O ₃₅ .

  Next, this solid was pulverized using a ball mill to obtain powder a. When the particle size of the powder a was measured by a laser diffraction scattering method (SALD-2100, manufactured by Shimadzu Corporation), the average particle size was 5 μm.

  In FIG. 2, the X-ray-diffraction result of the obtained powder a is shown.

  From the diffraction pattern of FIG. 2, it was confirmed that the powder a was amorphous. Hereinafter, the powder a is referred to as “material A powder”.

(Synthesis of wadalite compounds)
5 g of the powder of the material A and 20 g of calcium chloride (CaCl ₂ ) powder were mixed to obtain a mixed raw material.

  Next, this mixed raw material was heat-treated (chlorine treatment) under the following conditions.

  First, the mixed raw material was put in an alumina crucible with a lid, and the temperature was raised to 670 ° C. in air at a temperature rising rate of 400 ° C./hour. After holding the alumina crucible at this temperature for 3 hours, the alumina crucible was cooled to room temperature at a temperature drop rate of 400 ° C./hour in the same atmosphere.

  Next, the heat-treated product obtained from the alumina crucible was collected, washed with water, and filtered to obtain a white powder.

  In FIG. 3, the X-ray-diffraction result of the obtained white powder is shown.

  From the diffraction pattern of FIG. 3, it was confirmed that this white powder was a wadalite compound.

(Example 2)
A powder of material A was prepared in the same manner as in Example 1 described above. In addition, the material A powder was heat-treated in the same manner as in Example 1.

  However, in Example 2, the powder of the material A was not mixed with calcium chloride and was heat-treated as it was.

  In FIG. 4, the X-ray-diffraction result of the powder obtained after heat processing is shown.

  As shown in FIG. 4, the powder obtained after the heat treatment was hardly changed from that before the treatment, and a wadalite compound could not be obtained.

(Example 3)
A wadalite compound was produced by the following method.

  To 3 g of the material A powder obtained in Example 1, 2.4 g of a vehicle containing ethyl cellulose, butyl carbitol acetate (BCA) and terpineol was added and kneaded in an automatic mortar to prepare a paste.

  Using the printing machine, the obtained paste was uniformly applied on the surface of a glass substrate (AN100: manufactured by Asahi Glass Co., Ltd.) having a length of 20 mm, a width of 20 mm, and a thickness of 0.7 mm.

  Next, this glass substrate was heat-treated in air at 600 ° C. for 1 hour. Thereby, the film | membrane of the material A was installed in the surface of the glass substrate (film thickness of 18 micrometers).

  Next, this glass substrate was put into an alumina crucible with a lid together with calcium chloride powder (2 g), and the temperature was raised to 750 ° C. in air at a rate of 400 ° C./hour. After holding the alumina crucible at this temperature for 6 hours, the alumina crucible was cooled to room temperature at a temperature drop rate of 400 ° C./hour in the same atmosphere.

  Next, the glass substrate was recovered from the alumina crucible and washed with water. As a result, a glass substrate having a film-like substance formed on the surface was obtained.

  In FIG. 5, the X-ray-diffraction result of the obtained film-form substance is shown.

  From the diffraction pattern of FIG. 5, it was confirmed that this film-like substance was a wadalite compound.

  The wadalite compound produced by the method of the present invention can be used for, for example, a humidity sensor.

Claims (7)

A method for producing a wadalite compound represented by a composition of Ca ₁₂ Al _(14-x) Si _x O ₃₂ Cl _{(x + 2)} (where x = 0 to 4),
(I) a step of preparing an amorphous material A represented by a composition of Ca ₁₂ Al _(14-x) Si _x O _{(33 + x / 2)} (where x = 0 to 4);
(Ii) chlorinating the material A at a temperature of less than 850 ° C. to produce a wadalite compound;
A manufacturing method comprising: The step (ii)
(A) adding a metal chloride to the material A and heat-treating the resulting mixture at a temperature of less than 850 ° C., or (b) reducing the material A to less than 850 ° C. in an atmosphere containing a chlorine-containing gas. The manufacturing method of Claim 1 which has the process of heat-processing at the temperature of. The manufacturing method according to claim 2, wherein the metal chloride includes calcium chloride and / or potassium chloride, or the chlorine-containing gas includes hydrogen chloride gas and / or chlorine gas.   The manufacturing method according to claim 1, wherein the step (ii) is performed at a temperature of 620 ° C. or higher.   The step (i) includes a step of rapidly cooling a raw material obtained by blending calcium oxide, alumina, and silica in a predetermined ratio after being held and melted at a temperature of 1450 ° C to 1800 ° C. 5. The production method according to any one of 1 to 4.   The step (ii) includes a step of chlorinating the material A on a substrate, and a film-like wadalite compound is formed on the substrate. Production method.   The manufacturing method according to claim 6, wherein the substrate is a glass substrate.

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