Powdered release agent for crystalline glass plates, and method for manufacturing crystalline glass plates

Abstract

To provide a powder release agent for a crystal glass sheet, which can suppress the adhesion of talc-induced dirt to a crystal glass sheet, and a method for producing a crystal glass sheet.SOLUTION: A powder release agent 11 for a crystal glass sheet is used by adhering to the crystal glass sheet G1 in a firing process in which the crystal glass sheet G1 is fired to obtain the crystal glass sheet G2. The powder release agent 11 for a crystal glass sheet comprises denatured talc powder P with a heat loss ratio of 4.5% or less when heated at 1200°C for 2 hours. A method for producing the crystal glass sheet G2 includes a firing process in which the crystal glass sheet G1 is fired to obtain the crystal glass sheet G2. The powder release agent 11 for the crystal glass sheet is attached to the crystal glass sheet G1 in the firing process.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0005]

[0001] The present invention relates to a powder mold release agent for a crystalline glass plate and a method for manufacturing a crystallized glass plate.

Background Art

[0002] As disclosed in Patent Documents 1 to 3, in a firing step of firing a crystalline glass plate disposed on a setter to obtain crystallized glass, a powder mold release agent for a crystalline glass plate is used. The powder mold release agent for a crystalline glass plate is used, for example, by adhering it to the main surface of the crystalline glass plate disposed so as to be overlapped on the setter. Thereby, it is possible to suppress the crystallized glass plate after the firing step from adhering to the setter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] As the powder mold release agent for a crystalline glass plate as described above, for example, talc powder, alumina powder, etc. may be used. Since the hardness of talc powder is lower than that of alumina powder, when talc powder is used as the powder mold release agent for a crystalline glass plate, there is an advantage that the crystallized glass plate after firing is hardly scratched. However, there is a risk that the stain caused by talc adheres to the crystallized glass plate after firing, for example, deteriorating the quality of the crystallized glass plate.

[0005] The object of the present invention is to provide a powder release agent for crystalline glass plates that can suppress the adhesion of talc-induced stains to crystallized glass plates, and a method for manufacturing crystallized glass plates. [Means for solving the problem]

[0006] A powder release agent for crystalline glass plates that solves the above problems is a powder release agent for crystalline glass plates that is attached to the crystalline glass plate in a firing process to obtain a crystallized glass plate by firing the crystalline glass plate, and contains modified talc powder with a heating loss rate of 4.5% or less when heated at 1200°C for 2 hours.

[0007] In the above-mentioned powder release agent for crystalline glass plates, the Mohs hardness of the modified talc powder is preferably 3 or less. In the above-mentioned powder release agent for crystalline glass plates, it is preferable that the heat loss rate of the modified talc powder is 3.0% or more.

[0008] A method for manufacturing a crystallized glass plate that solves the above problems comprises a firing step of firing a crystalline glass plate to obtain a crystallized glass plate, wherein a powder release agent for crystalline glass plates is attached to the crystalline glass plate in the firing step, and 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.

[0009] In the firing step of the above-described method for manufacturing crystallized glass plates, it is preferable to arrange multiple crystalline glass plates on top of each other and to place the powder release agent for crystalline glass plates between adjacent crystalline glass plates. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the adhesion of talc-induced stains to the crystallized glass plate. [Brief explanation of the drawing]

[0011] [Figure 1] (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. [Modes for carrying out the invention]

[0012] 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. Also, the dimensional ratios of each part may differ from those of the actual components.

[0013] <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 in which the crystalline glass plate is fired.

[0014] The heat loss rate of the modified talc powder contained in the powder release agent for crystalline glass plates is preferably 3.0% or more. 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, in the range of 1 μm or more and 30 μm or less.

[0015] <Method for manufacturing powder release agent for crystalline glass plates> The manufacturing method of the powder release agent for the crystalline glass plate includes a heat treatment step of heat-treating the raw talc powder. As the raw talc powder, commercially available talc powder obtained by pulverizing talc ore can be used. The temperature condition in the heat treatment step is preferably within the range of 700°C or higher and 1200°C or lower, and more preferably within the range of 800°C or higher and 1100°C or lower.

[0016] For example, the higher the temperature in the heat treatment step, the more possible it is to obtain modified talc powder with a lower heat loss rate. Also, for example, the lower the temperature in the heat treatment step, the lower the hardness of the modified talc powder can be suppressed. The heating time in the heat treatment step is preferably within the range of, for example, 1 hour or longer and 5 hours or shorter. A well-known heating furnace can be used in the heat treatment step.

[0017] <Manufacturing method of the crystallized glass plate> The manufacturing method of the crystallized glass plate includes a firing step of firing the crystalline glass plate to obtain the crystallized glass plate. The crystalline glass plate for the powder release agent described above is adhered to the crystalline glass plate in the firing step.

[0018] The crystalline glass plate is formed from, for example, LAS (Li2O - Al2O3 - SiO2) - based crystalline glass. The LAS - based crystalline glass is a glass in which β - quartz solid solution or β - spodumene solid solution precipitates as the main crystal by heat treatment of the formed plate glass. [[ID=A]]

[0019] As shown in Fig. 1(a), in the manufacturing method of the crystallized glass plate G2, as a preparation step of the firing step, a step of arranging a plurality of crystalline glass plates G1, G1 on the setter S (shelf plate) along the thickness direction is performed. At this time, the powder release agent 11 for the crystalline glass plate is arranged between the crystalline glass plate G1 and the setter S, and between the crystalline glass plate G1 and the crystalline glass plate G1. The powder release agent 11 for the crystalline glass plate contains the modified talc powder P having a heat loss rate of 4.5% or less.

[0020] As a method for attaching the powder mold release agent 11 for the crystalline glass plate to the crystalline glass plate G1, for example, there are a method of spraying the powder mold release agent 11 for the crystalline glass plate onto the main surface of the crystalline glass plate G1, a method of spraying the powder mold release agent 11 for the crystalline glass plate onto the main surface of the crystalline glass plate G1 using an air flow, a method of applying the powder mold release agent 11 for the crystalline glass plate onto the main surface of the crystalline glass plate G1 using a coater, and the like. After attaching the powder mold release agent 11 for the crystalline glass plate to the main surface of the setter S, the crystalline glass plate G1 may be attached with the powder mold release agent 11 for the crystalline glass plate by arranging the crystalline glass plate G1 so as to overlap the setter S.

[0021] As shown in Fig. 1(b), the firing process is performed by heating the crystalline glass plate G1 in the heating furnace 12. By performing the crystallization of the crystalline glass in this firing process, a crystallized glass plate G2 is obtained as shown in Fig. 1(c). In Fig. 1(c), the crystallized glass plate G2 is shown in a matte pattern.

[0022] The crystallized glass plate G2 is washed by a well-known washing process and used for various purposes. Since the crystallized glass plate G2 has low thermal expansion properties, it can be suitably used for applications that require heat resistance. Examples of the uses of the crystallized glass plate G2 include, for example, a top plate for a cooker, a decorative material such as a top plate of kitchen equipment, a component of a heating appliance, a fireproof window, and the like.

[0023] Next, the operation and effects of the present embodiment will be described. (1) The powder mold release agent 11 for the crystalline glass plate is used by being attached to the crystalline glass plate G1 in the above firing process. The powder mold release agent 11 for the crystalline glass plate contains a modified talc powder P having a heating loss rate of 4.5% or less when heated under the conditions of 1200°C for 2 hours. According to this configuration, it is possible to suppress the adhesion of dirt caused by talc to the crystallized glass plate G2. Thereby, for example, it becomes possible to simplify the cleaning process for cleaning the crystallized glass plate G2. Therefore, the quality of the crystallized glass plate can be easily maintained.

[0024] Here, talc is hydrated magnesium silicate (3MgO·4SiO2·H2O), and the contamination adhering to the crystallized glass plate G2 after the firing process is thought to be caused by the detachment of crystal water contained in the talc during the firing process. By using modified talc powder P with a heating loss rate of 4.5% or less during the firing process, the amount of crystal water detached from the modified talc powder P during the firing process can be reduced. This is thought to suppress the adhesion of contamination to the crystallized glass plate G2 after the firing process.

[0025] (2) The Mohs hardness of the modified talc powder P contained in the powder release agent 11 for crystalline glass plates is preferably 3 or less. In this case, it is possible to suppress scratches on the crystalline glass plate G2 caused by the modified talc powder P.

[0026] (3) Preferably, the heat loss rate of the modified talc powder P contained in the powder release agent 11 for crystalline glass plates is 3.0% or more. In this case, the hardening of the modified talc powder P is suppressed, thereby preventing scratches on the crystalline glass plate G2 caused by the modified talc powder P.

[0027] (4) In the method for manufacturing crystallized glass plates G2, a powder release agent 11 for crystalline glass plates is attached to the crystalline glass plate G1 during the firing process. It is preferable that the firing process is carried out with multiple crystalline glass plates G1, G1 stacked on top of each other, and with the powder release agent 11 for crystalline glass plates placed between adjacent crystalline glass plates G1. In this case, for example, the space inside the heating furnace 12 used in the firing process can be used more effectively. Also, for example, the transport efficiency of the crystalline glass plate G1 or crystallized glass plate G2 can be increased. Therefore, the productivity of crystallized glass plates G2 can be increased.

[0028] Furthermore, adhesion between the two main surfaces where the crystallized glass plates G2 overlap is suppressed, and the adhesion of talc-induced stains to these main surfaces is also suppressed. As a result, even when the productivity of the crystallized glass plates G2 is increased as described above, a decrease in the quality of the crystallized glass plates G2 can be suppressed.

[0029] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0030] • In the firing process of the above method for manufacturing crystallized glass plate G2, multiple crystalline glass plates G1, G1 are arranged in a stacked manner, but the firing process may also be carried out by placing a single crystalline glass plate G1 on the setter S.

[0031] • In the firing process of the above method for manufacturing crystallized glass plate G2, two crystalline glass plates G1, G1 are arranged to overlap, but three or more crystalline glass plates G1, G1 may also be arranged to overlap.

[0032] The powder release agent 11 for crystalline glass plates may contain powders other than modified talc powder P. Examples of powders other than modified talc powder P include talc powder with a heating loss rate of more than 4.5% and powders other than talc powder. Examples of powders other than talc powder include inorganic oxide powders such as alumina powder. However, the content of the modified talc powder P in the powder release agent 11 for crystalline glass plates is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. [Examples]

[0033] Next, examples and comparative examples will be described. (Example 1) In Example 1, a powder release agent for crystalline glass plates was obtained by heat-treating commercially available talc powder (average particle size 10 μm) at 820°C for 2 hours to obtain a modified talc powder. The obtained powder release agent for crystalline glass plates was rubbed onto a sample of crystalline glass plate, and then a firing process was performed to obtain a crystallized glass plate. The firing process consisted of a primary firing at 800°C for 60 minutes and a secondary firing at 900°C for 20 minutes, performed consecutively at a predetermined temperature profile. After the obtained crystallized glass plate was slowly cooled, the powder release agent for crystalline glass plates adhering to the crystallized glass plate was wiped off with a cotton cloth to obtain an evaluation sample.

[0034] (Examples 2-4) As shown in Table 1, in Examples 2 to 4, powder release agents for crystalline glass plates were obtained in the same manner as in Example 1, except that the manufacturing conditions for the powder release agent for crystalline glass plates were changed. Evaluation samples for Examples 2 to 4 were obtained in the same manner as in Example 1, except that the powder release agents for crystalline glass plates obtained in this manner were used.

[0035] (Comparative Example 1) As shown in Table 1, in Comparative Example 1, a powder release agent for crystalline glass plates was obtained in the same manner as in Example 1, except that the manufacturing conditions for the powder release agent for crystalline glass plates were changed. An evaluation sample for Comparative Example 1 was obtained in the same manner as in Example 1, except that the powder release agent for crystalline glass plates obtained in this manner was used.

[0036] <Physical properties of powder release agents for crystalline glass plates> (Heating loss rate) 100 g of modified talc powder, a powder release agent for crystalline glass plates obtained in each example, was heated at 1200°C for 2 hours. Next, the mass W [g] of the modified talc powder after heating was measured, and the weight loss rate R was calculated using the following formula.

[0037] Heating loss rate R[%]=(100-W) / 100×100 The results are shown in Table 1. (Mohs hardness scale) The modified talc powder, which was used as a powder release agent for crystalline glass plates in each example, was measured for Mohs hardness using a Mohs hardness tester. The results are shown in Table 1.

[0038] <Evaluation of powder release agents for crystalline glass plates> (Stain-inhibiting effect) The evaluation samples for each example were visually observed and evaluated according to the following criteria.

[0039] No dirt adheres to the crystalline glass plate, demonstrating excellent dirt-inhibiting effect: ◎ There is some degree of dirt adhering to a portion of the crystalline glass plate, indicating good dirt-inhibiting effect: ○ The crystalline glass plate has dirt adhering to it, resulting in poor dirt-inhibiting effect: × (Injury suppression effect) The evaluation samples for each example were observed visually and with a double-scan high-precision laser displacement meter (manufactured by Keyence Corporation), and evaluated according to the following evaluation criteria.

[0040] No indentations caused by the powder release agent for crystalline glass plates were detected on the crystalline glass plate using a double-scan high-precision laser displacement meter, demonstrating excellent scratch suppression: ◎ While indentations caused by the powder release agent for crystalline glass plates are detected on the crystalline glass plate using a double-scan high-precision laser displacement meter, they are barely visible to the naked eye, indicating good scratch suppression: ○ Indentations caused by the powder release agent for crystalline glass plates were visually observed on the crystalline glass plate, indicating poor scratch prevention: ×

[0041] [Table 1] The powder release agents for crystalline glass plates in Examples 1-4 showed excellent stain suppression effects. The powder release agents for crystalline glass plates in Examples 1-3 also showed excellent scratch suppression effects. On the other hand, the powder release agent for crystalline glass plates in Comparative Example 1 showed inferior stain suppression effects. [Explanation of symbols]

[0042] 11…Powdered release agent for crystalline glass plates G1...Crystalline glass plate G2...Crystallized glass plate P...Modified talc powder

Claims

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 claim 2, wherein the heat loss rate of the modified talc powder is 3.0% or more.

4. The powder release agent for crystalline glass plates according to any one of claims 1 to 3, wherein the crystalline glass plate is made of LAS (Li₂O-Al₂O₃-SiO₂) type crystalline glass.

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 method for manufacturing a crystallized glass plate according to claim 5 or claim 6, wherein the crystalline glass plate is made of LAS (Li₂O-Al₂O₃-SiO₂)-based crystalline glass.

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