JP2024035279A - Method for manufacturing article - Google Patents

Abstract

To provide a method for manufacturing articles, capable of preventing a glaze layer from being colored in black even when fired at a low temperature.SOLUTION: The present invention relates to a method for manufacturing articles having a glaze layer. A glaze is used which contains glass powder having an average particle diameter of more than 0 μm and 20 μm or less. The glass powder is melted in the presence of an oxidizing agent at a temperature of 600°C or higher and 800°C or lower to form the glaze layer.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD This disclosure relates to a method of manufacturing an article.

Glass powder (frit raw material) is used in glazes for tiles, sanitary ware, etc. (see, for example, Patent Document 1). The glaze was used at a temperature of 1000°C or higher.

Japanese Patent Application Publication No. 2012-087029

In recent years, in consideration of environmental issues, attempts have been made to lower the firing temperature in order to reduce energy consumption. Therefore, it has become necessary to melt the frit raw material, which is one of the raw materials used, at a lower temperature.
However, when fired at a low temperature, a phenomenon in which the finely ground frit turned black was observed.

In view of the above circumstances, an object of the present disclosure is to provide a manufacturing method that can suppress blackening of the glaze layer even when firing at a low temperature.

A method for manufacturing an article having a glaze layer, the method comprising:
Production of an article, using a glaze containing glass powder with an average particle size of more than 0 μm and less than 20 μm, and forming the glaze layer by melting the glass powder at 600° C. or more and 800° C. or less in the presence of an oxidizing agent. Method.

FIG. 1 is a conceptual diagram showing an example of an article. FIG. 2 is a graph showing the relationship between the amount of hydrogen peroxide added and the brightness value.

The present disclosure will be described in detail below. In addition, when a numerical range is indicated using a "-", the lower limit value and the upper limit value are included unless otherwise specified. For example, the description "10-20" includes both the lower limit value "10" and the upper limit value "20". That is, "10-20" has the same meaning as "10 or more and 20 or less".

1. Method for manufacturing article 1 A method for manufacturing article 1 of the present disclosure is a method for manufacturing article 1 having glaze layer 3 .
The method for manufacturing article 1 uses a glaze containing glass powder with an average particle diameter of greater than 0 μm and less than 20 μm. In the method for manufacturing the article 1, the glaze layer 3 is formed by melting glass powder at 600° C. or higher and 800° C. or lower in the presence of an oxidizing agent. Regarding the glaze layer 3, there may be two or more layers.
(1) Article 1
Article 1 is not particularly limited. The article 1 has a glaze layer 3 located on the surface of a base 5. Suitable examples of the article 1 include tiles, sanitary ware, ceramics, tableware, roof tiles, and the like. As used herein, "sanitary ware" refers to ceramic products used around toilets and washrooms. Examples of sanitary ware include urinals, toilet bowls, toilet tanks, sink basins, hand wash basins, and the like. As used herein, "pottery" refers to ceramics made of feldspar, pottery stone, kaolin, and clay as raw materials, coated with glaze, and fired.
As the base 5, for example, in the case of sanitary ware, a pottery base composition (pottery base slurry) containing feldspar, pottery stone, kaolin, clay, frit, etc. as raw materials is shaped into a predetermined shape using a plaster mold or a resin mold. Examples include a base material 5 that has been molded and fired. Regarding the firing of the base material, the glaze is first fired at 1000°C or higher, and then the glaze is applied by dipping, pouring, overspraying, or spraying, and then the glaze is applied again at 600°C or higher. The article 1 may be obtained by firing at 800°C or lower, or the article 1 may be obtained by applying glaze directly to the unfired base 5 and firing once at 600°C or higher and 800°C or lower. .

(2) Glaze layer 3 (glaze layer)
The glaze layer 3 is formed by firing a glaze. The glaze contains glass powder with an average particle diameter of 0 μm or more and 20 μm or less. The glaze may contain, for example, feldspar, clay, limestone, silica, talc, and the like.
The content of glass powder in the glaze is not particularly limited. The content of the glass powder is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, based on the total mass of solids contained in the glaze.

(3) Glass powder Glass powder (frit) is obtained by melting a glass raw material adjusted to a desired composition at a temperature of 1000° C. or higher, cooling it, turning it into amorphous glass, and pulverizing it.
(3.1) Glass composition The glass composition is not particularly limited. A preferred example of the glass composition is a composition that can be melted at 600°C or higher and 800°C or lower. By using glass compositions that can be melted at low temperatures, the firing temperature of tiles and sanitary ware can be lowered, taking environmental concerns into consideration and reducing energy consumption.
The glass composition is not particularly limited as long as it can be melted at 600°C or higher and 800°C or lower. Examples of the glass composition include phosphate glass, vanadium glass, borosilicate glass, soda lime glass, and alkali aluminosilicate glass.
Examples of glass compositions are shown below.

<Glass composition example>
SiO ₂ 0.5 mol% or more and 5 mol% or less Al ₂ O ₃ 3 mol% or more and 12 mol% or less B ₂ O ₃ 21 mol% or more and 25 mol% or less Li ₂ O 8 mol% or more and 14 mol% or less K ₂ O 2 mol% or more and 6 mol% or less Na ₂ O 20 mol% or more and 29 mol% or less P ₂ O ₅ 21 mol% or more and 35 mol% or less

Specific glass composition example SiO ₂ 1 mol%
_{Al2O3 10mol} %
_{B2O3 23mol} %
_Li2O 12mol%
_K2O 4mol%
_Na2O 27mol%
_{P2O5 23mol} %

<Glass composition example>
SiO ₂ 40 mol% or more and 46 mol% or less Al ₂ O ₃ 0.5 mol% or more and 5 mol% or less B ₂ O ₃ 0 mol% or more and 5 mol% or less Li ₂ O 7 mol% or more and 13 mol% or less K ₂ O 6 mol% or more and 11 mol% or less Na ₂ O 12 mol% or more and 22 mol% or less P ₂ O ₅ 0.5 mol% or more and 10 mol% or less ZnO 2 mol% or more and 5 mol% or less V ₂ O ₅ 1 mol% or more and 5 mol% or less TiO ₂ 5 mol% or more and 16 mol% or less

Specific glass composition example SiO ₂ 44 mol%
_{Al2O3 1mol} %
B ₂ O ₃ 0 mol%
_Li2O 9mol%
_K2O 9mol%
_Na2O 15mol%
_{P2O5 1mol} %
ZnO 4mol%
_{V2O5 3mol} %
_TiO2 14mol%

Specific glass composition example SiO ₂ 44 mol%
_{Al2O3 1mol} %
_{B2O3 1mol} %
_Li2O 9mol%
_K2O 8mol%
_Na2O 20mol%
_{P2O5 1mol} %
ZnO 3mol%
_{V2O5 2mol} %
_TiO2 11mol%

(3.2) Average particle size The average particle size of the glass powder is set to be larger than 0 μm from the viewpoint of effectively suppressing blackening during low-temperature firing or from the viewpoint of reducing the amount of oxidizing agent added during low-temperature firing. It is 20 μm or less, preferably 10 μm or more and 20 μm or less, and more preferably 15 μm or more and 20 μm or less. If the average particle size is within this range, the particle size will be fine, and it is assumed that oxygen defects will increase more during low-temperature firing, making it easy to blacken and requiring an increase in the amount of oxidizing agent added. Even if the amount of addition is reduced, blackening can be effectively suppressed.
The average particle diameter can be measured using a laser diffraction particle size distribution analyzer. "Average particle size" means 50% average particle size (D50). D50 is the median diameter on a number basis, and means the average particle diameter of 50% in the cumulative distribution.

(4) Oxidizing agent In the present disclosure, glass powder is melted in the presence of an oxidizing agent. The cause of the blackening is presumed to be oxygen defects in the glass powder that occur during pulverization. It is thought that blackening caused by oxygen defects is suppressed by supplying oxygen to the glass from the oxidizing agent during firing.
The oxidizing agent is not particularly limited. From the viewpoint of effectively suppressing blackening during firing, the oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide, nitric acid, and nitrates. Examples of nitrates include potassium nitrate and sodium nitrate.
The oxidizing agent is preferably a hydrogen peroxide solution from the viewpoint of suppressing foaming due to nitric acid gas generation during glass melting.
When the oxidizing agent is a hydrogen peroxide solution, the amount of hydrogen peroxide is preferably 0.5 × 10 ^-6 mol or more per 1 g of glass powder, from the viewpoint of increasing the effect of suppressing blackening caused by oxygen defects. , more preferably 1.8×10 ⁻⁶ mol or more, and still more preferably 2.5×10 ⁻⁶ mol or more. The upper limit of hydrogen peroxide is not particularly limited. The amount of hydrogen peroxide can be, for example, 15.0×10 ⁻⁶ mol or less per 1 g of glass powder.
When the oxidizing agent is nitric acid, the amount of nitric acid is preferably 0.8×10 ⁻⁶ mol or more per 1 g of glass powder, and 1.0× It is more preferably 10 ⁻⁶ mol or more, and even more preferably 2.0×10 ⁻⁶ mol or more. The upper limit of nitric acid is not particularly limited. In order to suppress foaming of the glaze layer 3, the amount of nitric acid is preferably 6.0×10 ⁻⁶ mol or less, more preferably 5.0×10 ⁻⁶ mol or less per 1 g of glass powder. It is preferably 4.0×10 ⁻⁶ mol or less, and more preferably 4.0×10 −6 mol or less.
When the oxidizing agent is a nitrate, the nitrate is preferably 0.8×10 ⁻⁶ mol or more per 1 g of glass powder, and 1.0× It is more preferably 10 ⁻⁶ mol or more, and even more preferably 2.0×10 ⁻⁶ mol or more. The upper limit of nitrate is not particularly limited. In order to suppress foaming of the glaze layer 3, the amount of nitrate is preferably 6.0×10 ⁻⁶ mol or less, more preferably 5.0×10 ⁻⁶ mol or less per 1 g of glass powder. It is preferably 4.0×10 ⁻⁶ mol or less, and more preferably 4.0×10 −6 mol or less.

2. Effects of the manufacturing method of the present disclosure In the manufacturing method of the present disclosure, it is possible to form a glaze layer in which blackening is suppressed even when melted at a low temperature using glass powder with an average particle diameter of more than 0 μm and less than 20 μm.
When at least one selected from the group consisting of hydrogen peroxide, nitric acid, and nitrates is used as the oxidizing agent, the effect of suppressing blackening is good.
When a hydrogen peroxide solution is used as the oxidizing agent and the amount of hydrogen peroxide is 0.5×10 ⁻⁶ mol or more and 15.0×10 ⁻⁶ mol or less per 1 g of glass powder, air bubbles are well suppressed and blackening occurs. is also well suppressed.

Examples will be described in detail below.

1. Experiment (1) Comparative example 1
Glass was produced by melting phosphate glass adjusted to the following composition at 1100° C. for 1 hr, pouring it out, and rapidly cooling it. The produced glass was crushed in an alumina mortar. The average particle size of the glass powder was 100 μm. The average particle diameter was measured using a laser diffraction particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., "MT3000II (model number)"). 1 g of the obtained glass powder was mixed with water at a ratio of 0.300 mL/g to form a slurry, which was applied to an alumina plate and dried at 110° C. for 30 minutes.
Thereafter, it was fired at 600°C for 2 hours, and the glass was removed from the alumina plate and polished. The brightness value (an index representing brightness) was calculated from the scanned image of the polished glass, and the degree of blackening was evaluated. The brightness value was determined from an image obtained by scanning a sample polished to a thickness of about 1 mm with a scanner. The brightness value when scanning without placing a sample was 255.
To read the brightness values, public domain software called ImageJ, which can be found at the following URL, was used, a size of approximately 4 mm square was manually specified, and the average brightness value of that portion was determined.
http://scienceandtechnology. jp/archives/25990#Image_J-4

<Glass composition>
_SiO2 1mol%
_{Al2O3 10mol} %
_{B2O3 23mol} %
_Li2O 12mol%
_K2O 4mol%
_Na2O 27mol%
_{P2O5 23mol} %

(2) Comparative example 2
An experiment was carried out in the same manner as in Comparative Example 1 except that the average particle size of the glass powder was 50 μm.

(3) Comparative example 3
An experiment was carried out in the same manner as in Comparative Example 1 except that the average particle diameter of the glass powder was 18 μm.

(4) Example 1
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 0.8×10 ⁻⁶ mol per gram of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(5) Example 2
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 1.5×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(6) Example 3
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 2×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(7) Example 4
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 2.9×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(8) Example 5
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 5×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(9) Example 6
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 6×10 ⁻⁶ mol per gram of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(10) Example 7
The average particle diameter of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 10×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(11) Example 8
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 12×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(12) Example 9
The average particle size of the glass powder was 18 μm.
Hydrogen peroxide solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The hydrogen peroxide solution contained hydrogen peroxide at a ratio of 14.5×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(13) Example 10
The average particle size of the glass powder was 18 μm.
Nitric acid was mixed at a ratio of 1.3×10 ⁻⁶ mol to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(14) Example 11
The average particle diameter of the glass powder was 18 μm.
Nitric acid was mixed at a ratio of 3.9×10 ⁻⁶ mol to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(15) Example 12
The average particle size of the glass powder was 18 μm.
An aqueous sodium nitrate solution was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The aqueous sodium nitrate solution contained sodium nitrate at a rate of 3.8×10 ⁻⁶ mol per 1 g of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

(16) Comparative example 4
The average particle size of the glass powder was 18 μm.
Aqueous ammonia was mixed at a ratio of 0.300 mL/g to 1 g of glass powder to form a slurry, which was applied to an alumina plate and dried.
The ammonia water contained ammonia at a ratio of 3.8×10 ⁻⁶ mol per gram of glass powder.
The experiment was conducted in the same manner as Comparative Example 1 except for the above.

2. Results The results are also listed in Table 1.
In the case of Comparative Examples 1 and 2 in which the average particle diameter of the glass powder was as large as 100 μm and 50 μm, the brightness value was high even without adding an oxidizing agent, and the glass powder was in a transparent molten state.
In the case of Comparative Example 3 in which the average particle size of the glass powder was as small as 18 μm, the brightness value was low and the glass was in a black molten state unless an oxidizing agent was added.
In the case of Example 1-12 in which the average particle size of the glass powder was as small as 18 μm, by adding an oxidizing agent, the brightness value was higher than that in Comparative Example 3, and blackening could be suppressed.
In the case of Comparative Example 4, in which the average particle diameter of the glass powder was as small as 18 μm, even if a reducing agent was added, the brightness value was lower than that of Comparative Example 3, and the glass powder was in a black molten state.
FIG. 2 shows the relationship between the amount of hydrogen peroxide added and the brightness value. The amount of hydrogen peroxide added in FIG. 1 is the amount added per 1 g of glass powder. From this graph, the amount of hydrogen peroxide added is preferably 0.5×10 ⁻⁶ mol or more and 15.0×10 ⁻⁶ mol or less, and 1.8×10 ⁻⁶ mol or more per 1 g of glass powder. It can be confirmed that the amount is more preferably 15.0×10 ⁻⁶ mol or less, and even more preferably 2.5×10 ⁻⁶ mol or more and 15.0×10 ⁻⁶ mol or less.

1... Article 3... Glaze layer 5... Base material

Claims (3)

A method for manufacturing an article having a glaze layer, the method comprising:
Production of an article, using a glaze containing glass powder with an average particle size of more than 0 μm and less than 20 μm, and forming the glaze layer by melting the glass powder at 600° C. or more and 800° C. or less in the presence of an oxidizing agent. Method. The method for producing an article according to claim 1, wherein the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, nitric acid, and nitrates. The oxidizing agent is hydrogen peroxide solution,
Production of the article according to any one of claims 1 and 2, wherein hydrogen peroxide is 0.5 x 10 ^-6 mol or more and 15.0 x 10 ^-6 mol or less per 1 g of the glass powder. Method.

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