JP-7855837-B2 - Powdered release agent for crystalline glass plates, and method for manufacturing crystalline glass plates

Inventors

• 奥村 哲也

Assignees

• 日本電気硝子株式会社

Dates

Publication Date

20260511

Application Date

20210716

Claims (7)

1. A powder release agent for crystalline glass plates, used by adhering it to the crystalline glass plate in a firing process to obtain a crystallized glass plate by firing the crystalline glass plate, A powder release agent for crystalline glass plates, containing modified talc powder with a heating loss rate of 4.5% or less when heated at 1200°C for 2 hours.
2. The powder release agent for crystalline glass plates according to claim 1, wherein the Mohs hardness of the modified talc powder is 3 or less.
3. The powder release agent for crystalline glass plates according to claim 1 or 2, wherein the heat loss rate of the modified talc powder is 3.0% or more.
4. The crystalline glass plate is LAS (Li 2 O-Al 2 O 3 -SiO 2 A powder release agent for crystalline glass plates according to any one of claims 1 to 3, comprising a crystalline glass of the ) system.
5. A method for manufacturing a crystallized glass plate, comprising a firing step to obtain a crystallized glass plate by firing a crystalline glass plate, In the firing process, a powder release agent for crystalline glass plates is applied to the crystalline glass plate. A method for producing a crystallized glass plate, wherein the powder release agent for the crystalline glass plate contains a modified talc powder whose heat loss rate when heated at 1200°C for 2 hours is 4.5% or less.
6. The method for manufacturing a crystallized glass plate according to claim 5, wherein the firing step is carried out with a plurality of crystalline glass plates arranged in a stacked manner, and the powder release agent for crystalline glass plates placed between adjacent crystalline glass plates.
7. The crystalline glass plate is LAS (Li 2 O-Al 2 O 3 -SiO 2 A method for producing a crystallized glass plate according to claim 5 or claim 6, comprising a crystalline glass of the ) system.

Description

This invention relates to a powdered mold release agent for crystalline glass plates and a method for producing crystalline glass plates. As disclosed in Patent Documents 1 to 3, in the firing process to obtain crystallized glass by firing crystalline glass plates placed on a setter, a powder release agent for crystalline glass plates is used. The powder release agent for crystalline glass plates is used by, for example, adhering it to the main surface of the crystalline glass plates that are placed in a stacked manner on the setter. This prevents the crystallized glass plates from adhering to the setter after the firing process. Japanese Patent Publication No. 2001-348242Japanese Patent Publication No. 2016-044103Japanese Patent Publication No. 2020-070212 (a) is an explanatory diagram showing a crystalline glass plate fired in the firing process in this embodiment, (b) is a schematic diagram showing the firing process, and (c) is a schematic diagram showing a crystallized glass plate. The following describes one embodiment of a powder release agent for crystalline glass plates and a method for manufacturing crystallized glass plates. Note that, for the sake of clarity, some parts of the structure may be exaggerated or simplified in the drawings. Furthermore, the dimensional ratios of each part may differ from those of the actual components. <Powdered release agent for crystalline glass plates> The powder release agent for crystalline glass plates is used by adhering it to the crystalline glass plate during the firing process to obtain a crystallized glass plate. The powder release agent for crystalline glass plates contains modified talc powder with a heating loss rate of 4.5% or less when heated at 1200°C for 2 hours. When the heating loss rate of the modified talc powder is 4.5% or less, it is possible to suppress the adhesion of talc-induced contamination to the crystallized glass plate during the firing process of the crystalline glass plate. The heat loss rate of the modified talc powder contained in the powder release agent for crystalline glass plates is preferably 3.0% or higher. In this case, the hardness of the modified talc powder can be kept low, thus preventing scratches on the crystalline glass plate. The Mohs hardness of the modified talc powder is preferably, for example, 3 or less. The average particle size of the modified talc powder is preferably, for example, within the range of 1 μm to 30 μm. <Method for manufacturing powder release agent for crystalline glass plates> The method for producing a powder release agent for crystalline glass plates includes a heat treatment step in which the raw material, talc powder, is heat-treated. Commercially available talc powder obtained by crushing talc ore can be used as the raw material. The temperature conditions in the heat treatment step are preferably in the range of 700°C to 1200°C, and more preferably in the range of 800°C to 1100°C. For example, the higher the temperature during the heat treatment process, the lower the heat loss rate of the modified talc powder. Conversely, for example, the lower the temperature during the heat treatment process, the lower the hardness of the modified talc powder can be. The heating time during the heat treatment process is preferably within the range of, for example, 1 hour or more and 5 hours or less. A well-known heating furnace can be used for the heat treatment process. <Method for manufacturing crystallized glass plates> The method for manufacturing crystallized glass plates includes a firing step in which a crystalline glass plate is fired to obtain a crystallized glass plate. The crystalline glass plate in the firing step is coated with the aforementioned powder release agent for crystalline glass plates. Crystalline glass plates are formed, for example, from LAS ( Li₂O - Al₂O₃ -SiO₂ ) crystalline glass. LAS crystalline glass is a type of glass in which a β-quartz solid solution or a β-spodumene solid solution precipitates as the main crystal upon heat treatment of the formed glass plate. As shown in Figure 1(a), in the manufacturing method of crystallized glass plate G2, a preparation step for the firing process is performed, in which multiple crystalline glass plates G1, G1 are arranged on a setter S (shelf) so as to be stacked along the thickness direction. At this time, a powder release agent 11 for crystalline glass plates is placed between the crystalline glass plate G1 and the setter S, and between the crystalline glass plates G1 and G1. The powder release agent 11 for crystalline glass plates contains modified talc powder P with a heating loss rate of 4.5% or less. Methods for applying the powder release agent 11 for crystalline glass plates to the crystalline glass plate G1 include, for example, sprinkling the powder release agent 11 on the main surface of the crystalline glass plate G1, blowing the powder release agent 11 onto the main surface of the crystalline glass plate G1 using an a