Firing markers
A firing marker composition of Fe2O3, ZnO, and NiO forms stable spinel structures to prevent ink volatilization, ensuring markings endure multiple high-temperature firings, addressing the issue of conventional marker disappearance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NORITAKE MACHINE TECHNO CO LTD
- Filing Date
- 2025-12-11
- Publication Date
- 2026-07-17
AI Technical Summary
Conventional firing markers used in high-temperature processes tend to lose their markings due to ink volatilization during repeated high-temperature firings, leading to the disappearance of characters and symbols.
A firing marker composition comprising Fe2O3, ZnO, and NiO, with optional CuO, is developed to enhance heat resistance by forming stable spinel-structured composite metal oxides that prevent iron ion diffusion, ensuring the markings remain intact even after multiple high-temperature treatments.
The proposed composition exhibits excellent heat resistance, maintaining markings on objects even after multiple high-temperature firings, with Fe2O3, ZnO, and NiO forming stable spinel structures that suppress iron ion liberation, thereby preserving the markings effectively.
Smart Images
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Abstract
Description
Technical Field
[0001] The technology disclosed herein relates to firing markers.
Background Art
[0002] In the manufacture of inorganic products (electronic components, powder materials, molded bodies, etc.), a firing process may be performed in which the firing target is heated at a high temperature of 1000 °C or higher. At this time, characters, symbols, figures (hereinafter referred to as "characters, etc.") indicating the manufacturing number, firing date and time, etc. may be described on the firing target. For such description of characters, etc., for example, a firing marker containing an inorganic pigment can be used. An example of this firing marker is described in Patent Document 1. In the firing marker (identification label) described in this Patent Document 1, iron oxide powder with high purity (purity of 90% or more) is used.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, among the firing targets, there are those in which a high-temperature (for example, 1200 °C or higher) firing process is repeated a plurality of times. However, when a high-temperature firing process is repeated on a conventional firing marker, there is a risk that the characters, etc. described on the firing target will disappear due to volatilization of the ink or the like caused by being exposed to high temperatures many times. The technology disclosed herein has been made to solve such problems, and an object thereof is to provide a firing marker having heat resistance superior to the conventional one.
Means for Solving the Problems
[0005] The firing marker disclosed herein contains a main component consisting of Fe2O3, ZnO, NiO, and CuO. The main component of this glass composition is composed of the following components when the total mass of the main component is 100 mass%. Fe2O360~72 mass% ZnO 15-25 mass% NiO 8~12 mass% CuO 1~5 mass%
[0006] The inventors conducted numerous experiments and studies to create a firing marker with excellent heat resistance, and as a result, succeeded in creating a firing marker containing Fe2O3, ZnO, NiO, and CuO in the above-mentioned ratios. Surprisingly, this firing marker exhibited excellent heat resistance, hardly disappearing even after multiple firing treatments at a high temperature of 1500°C. [Modes for carrying out the invention]
[0007] Preferred embodiments of the present invention will be described below. Matters other than those specifically mentioned herein that are necessary for carrying out the present invention (for example, the method for manufacturing firing markers) can be understood as design matters for those skilled in the art based on the prior art. The present invention can be carried out based on the contents disclosed herein and common technical knowledge in the art. In the following description, "A to B (where A and B are arbitrary values)" includes not only A or greater and B or less, but also greater than A and less than B.
[0008] ≪Markers for firing≫ The firing markers disclosed herein are used to mark objects to be fired, such as letters, symbols, and figures. The term "object to be fired" here is not limited to specific objects but broadly encompasses anything that can be heated during the firing process. For example, the object to be fired here includes not only precursors of inorganic products (electronic components, powder materials, molded bodies, etc.), but also firing containers containing such precursors, the inner walls of firing furnaces, structural materials, rollers, heaters, thermocouples, and the like.
[0009] Furthermore, the form of the firing marker is not limited to the technology disclosed herein. For example, the firing marker disclosed herein may take the form of a rod-shaped molded body (chalk), a high-viscosity liquid (paste), or a low-viscosity liquid (ink). This firing marker can write desired characters, etc., by adhering various components, described later, to the object to be fired. The means of adhering the components of the firing marker to the object to be fired are not particularly limited. For example, if a chalk-shaped firing marker is used, characters, etc., can be written by rubbing the firing marker onto the object to be fired. If a paste-shaped firing marker is used, characters, etc., can be written by applying the firing marker to the object to be fired. And if an ink-shaped firing marker is used, characters, etc., can be written by printing with an inkjet device or the like.
[0010] 1. Main component Next, the main components of the firing marker disclosed herein will be described. The main components of the firing marker disclosed herein consist of Fe2O3, ZnO, NiO, and CuO. When the total mass of these main components is 100 mass%, the composition of the main components is as follows. Fe2O360~72 mass% ZnO 15-25 mass% NiO 8~12 mass% CuO 1~5 mass%
[0011] Experiments have confirmed that firing markers containing the main components of the above composition have excellent heat resistance, hardly disappearing even after multiple high-temperature firing treatments. While not intended to limit the technology disclosed herein, the reason for this improved heat resistance is presumed to be as follows: The firing marker disclosed herein contains Fe2O3. While Fe2O3 is an inexpensive material that can write clear letters, it also contains iron ions (Fe) when exposed to high-temperature environments. 3+The conventional firing marker has the characteristic of being easily liberated. Furthermore, if iron ions in the firing marker diffuse to the object being fired, there is a risk that the letters or other markings on the object will disappear. In contrast, the firing marker disclosed herein contains ZnO, NiO, and CuO in addition to Fe2O3. These additive components react with Fe2O3 during the firing process to generate spinel-structured composite metal oxides (ZnFe2O4, NiFe2O4, CuFe2O4). These spinel-structured composite metal oxides can maintain a stable crystal structure even in high-temperature environments, thus preventing the liberation of iron ions during the firing process. As a result, the diffusion of iron ions to the object being fired is suppressed, preventing the letters or other markings on the object from disappearing.
[0012] In this specification, "main component" refers to the inorganic component that accounts for 90 mass% or more when the total mass of inorganic components in the firing marker is set to 100 mass%. That is, when the total mass of inorganic components in the firing marker is set to 100 mass%, the total content of Fe2O3, ZnO, NiO, and CuO is 90 mass% or more. From the viewpoint of obtaining better heat resistance, the content of the main component is preferably 92.5 mass% or more, more preferably 95 mass% or more, even more preferably 97.5 mass% or more, and particularly preferably 99 mass% or more. On the other hand, the upper limit of the content of the main component is not particularly limited and may be 100 mass% (i.e., without minor components).
[0013] As described above, the main components of the firing marker disclosed herein are Fe2O3, ZnO, NiO, and CuO. Each component is described below.
[0014] (1) Iron oxide (Fe2O3) Fe2O3 is an inexpensive dark brown powder and is therefore suitable as an inorganic pigment in firing markers. When the total mass of the main components is 100 mass%, the Fe2O3 content is set to 60 mass% or more. This allows for clear markings of characters, etc., on the object to be fired. From the viewpoint of improving the visibility of the marked characters, etc., the Fe2O3 content is preferably 62 mass% or more, more preferably 63 mass% or more, even more preferably 64 mass% or more, and particularly preferably 65 mass% or more. On the other hand, in the firing marker disclosed herein, the upper limit of the Fe2O3 content is set to 72 mass% or less. This ensures that the content of additive components other than Fe2O3 (ZnO, NiO, CuO) is kept above a certain level. From the viewpoint of allowing the functions of other additive components to be properly exercised, the upper limit of the Fe2O3 content is preferably 70 mass% or less, more preferably 68 mass% or less, and particularly preferably 66 mass% or less.
[0015] (2) Zinc oxide (ZnO) ZnO is one of the additive components that improves the heat resistance of firing markers. This heat resistance improvement effect of ZnO is presumed to be due to the following reasons. First, ZnO reacts with Fe2O3 during firing to produce ZnFe2O4. Since ZnFe2O4 has excellent chemical stability in high-temperature environments, it can suppress the disappearance of the firing marker due to the diffusion of Fe ions. Furthermore, ZnFe2O4 has the characteristic of having a lower formation temperature (around 700°C to 750°C) compared to other spinel structure composite metal oxides. For this reason, ZnO is presumed to contribute particularly to suppressing the diffusion of Fe ions in the initial stages of firing. From the viewpoint of appropriately exhibiting this heat resistance improvement effect in the initial stages of firing, the ZnO content is set to 15 mass% or more when the total mass of the main components is 100 mass%. Furthermore, from the viewpoint of further improving heat resistance in the initial stages of firing, the ZnO content is preferably 16 mass% or more, more preferably 17 mass% or more, even more preferably 18 mass% or more, and particularly preferably 19 mass% or more. On the other hand, from the viewpoint of ensuring the content of other components (Fe2O3, NiO, CuO), the upper limit of the ZnO content is set to 25 mass% or less (preferably 22 mass% or less, more preferably 23 mass% or less, even more preferably 24 mass% or less, and particularly preferably 20 mass% or less).
[0016] (3) Nickel oxide (NiO) NiO is also an additive component used to improve the heat resistance of the firing marker. This NiO also reacts with Fe2O3 during the firing process to form a spinel-structured composite metal oxide (NiFe2O4). This NiFe2O4 has a high formation temperature (around 850°C to 950°C) and is characterized by having the highest durability in high-temperature environments. For this reason, NiO is presumed to contribute particularly to improving heat resistance in the later stages of firing. From the viewpoint of appropriately improving heat resistance in the later stages of firing, the NiO content is set to 8 mass% or more when the total mass of the main components is 100 mass%. Furthermore, from the viewpoint of further improving heat resistance in the later stages of firing, the NiO content is preferably 8.5 mass% or more, more preferably 9 mass% or more, even more preferably 9.5 mass% or more, and particularly preferably 9.8 mass% or more. On the other hand, from the viewpoint of ensuring the content of other components (Fe2O3, ZnO, CuO), the upper limit of the NiO content is set to 12 mass% or less (preferably 11.5 mass% or less, more preferably 11 mass% or less, even more preferably 10.5 mass% or less, and especially preferably 10 mass% or less).
[0017] (4) Copper oxide (CuO) CuO is also an additive component for improving the heat resistance of the firing marker. This CuO also reacts with Fe2O3 during firing to form a composite metal oxide (CuFe2O4) with a spinel structure. The formation temperature of this CuFe2O4 is intermediate between ZnFe2O4 and NiFe2O4 (about 800 °C to 850 °C). Therefore, it is presumed that CuO particularly contributes to the improvement of heat resistance in the middle stage of firing. From the viewpoint of more appropriately improving the heat resistance in the middle stage of firing, when the total mass of the main components is 100 mass%, the content of CuO is set to 1 mass% or more. Further, from the viewpoint of further improving the heat resistance in the middle stage of firing, the content of CuO is preferably 2 mass% or more, more preferably 3 mass% or more, still more preferably 4 mass% or more, and particularly preferably 4.2 mass% or more. On the other hand, from the viewpoint of ensuring the content of other components (Fe2O3, ZnO, NiO), the upper limit of the content of CuO is set to 5 mass% or less (preferably 4.8 mass% or less, more preferably 4.6 mass% or less, and particularly preferably 4.4 mass% or less).
[0018] 2. Other components The main components of the firing marker disclosed herein have been described above. Since the firing marker disclosed herein has the above-described main components, it can exhibit excellent heat resistance. On the other hand, the firing marker disclosed herein may contain components other than the above-described main components. Hereinafter, other components that may be contained in the firing marker will be described.
[0019] (1) Minor components The firing marker disclosed herein may contain inorganic components (secondary components) other than the above main components. Examples of such secondary components include SiO2, Al2O3, MnO, MgO, Cr2O3, Bi2O3, P2O5, CaO, So3, TiO2, V2O5, ZrO2, Br, etc. These secondary components may be intentionally added or may be unavoidable impurities mixed in from raw materials, manufacturing processes, etc. When the total mass of the inorganic components is 100 mass%, the content of the secondary components (total content of inorganic components other than the main component) is preferably 10 mass% or less, more preferably 4 mass% or less, still more preferably 2 mass% or less, and particularly preferably 1 mass% or less. This ensures a sufficient content of the main component, and thus the heat resistance improvement effect by the technology disclosed herein can be more appropriately exerted. The lower limit value of the content of the secondary components is not particularly limited and may be 0 mass% (i.e., no secondary components are included).
[0020] (2) Organic components In addition, the firing marker disclosed herein may appropriately add any organic component according to its form. For example, in the case of a chalk-shaped firing marker, a binder resin may be added as the organic component. The binder resin can be any conventionally known binder resin that can be used for forming chalk without particular limitation. Examples of such a binder resin include carboxymethyl cellulose, polyvinyl alcohol, gelatin, starch, etc. When the total amount of the inorganic components is 100 mass%, the addition amount of the binder resin is 1 mass% to 10 mass% (preferably 2 mass% to 8 mass%, more preferably 3 mass% to 5 mass%). This makes it possible to easily form a firing marker having appropriate strength.
[0021] Furthermore, in the case of paste-type firing markers, it is advisable to add a thickening agent as an organic component. This makes it possible to prepare a firing marker (paste) with excellent adhesion to the object to be fired. On the other hand, in the case of ink-type firing markers, it is advisable to add a dispersant as an organic component. This makes it possible to prepare a firing marker (ink) that exhibits excellent printability when using a printing device. Note that these organic components can be conventionally known materials without any particular restrictions and do not limit the technology disclosed herein, so a detailed explanation is omitted. Moreover, organic components are not essential components of the firing markers disclosed herein. For example, even if inorganic components are pressure-molded without adding a binder resin, a chalk-type firing marker can be molded.
[0022] [Example Test] The following describes test examples relating to the technology disclosed herein. However, the following description is not intended to limit the technology disclosed herein to those shown in the test examples.
[0023] 1. Sample preparation In this experiment, a mixed powder was first prepared by mixing Fe2O3, ZnO, NiO, and CuO in predetermined ratios. Next, a raw material paste was prepared by mixing this mixed powder with water in a ratio of 93.8:6.2. This raw material paste was then pressure-molded into a rod shape (30 MPa, 30 seconds) and subsequently dried at 60°C for 24 hours. This process produced a chalk-like firing marker.
[0024] In this study, three types of firing markers (Samples 1-3) with different main component compositions were prepared. Elemental analysis of each of Samples 1-3 was then performed using X-ray fluorescence analysis. The analysis results are shown in Table 1. The units of the values in Table 1 are "mass%".
[0025] [Table 1]
[0026] 2. Evaluation Test In this experiment, alumina ceramic plates were prepared for firing. Next, lines approximately 5 mm thick were drawn on the surface of the ceramic plates using firing markers (Samples 1-3). Then, these ceramic plates were subjected to a firing process at 1500°C for 3 hours, repeated 10 times. After each firing process, the lines drawn with the firing markers were visually inspected to see if they had disappeared. The results are shown in Table 2.
[0027] [Table 2]
[0028] In the firing test described above, the firing marker disappeared from Sample 1 after the second firing process. On the other hand, the firing marker remained in Samples 2 and 3 even after 10 firing processes. From this, it was found that by blending Fe2O3, ZnO, NiO, and CuO in appropriate ratios, a firing marker with excellent heat resistance can be achieved. In Sample 2, the firing marker had become slightly lighter after the 10th firing process. On the other hand, the density of the firing marker in Sample 3 had hardly changed even after the 10th firing process. From this, it was found that Sample 3 had better heat resistance than Sample 2.
[0029] The specific examples of the technologies disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples described above.
Claims
1. A molded body applied to a firing container or firing furnace in which the firing process is repeated multiple times, Fe ２ O ３ It contains a main component consisting of ZnO, NiO, and CuO, and a binder resin. The aforementioned main component, when the total mass of the main component is set to 100 mass%, Fe ２ O ３ 60~72mass%; ZnO 15-25 mass%; NiO 8-12 mass%; CuO 1-5 mass% A firing marker composed of [components].
2. The firing marker according to claim 1, wherein when the total mass of inorganic components contained in the firing marker is 100 mass%, the total content of the main components is 95 mass or more.
3. When the total mass of the aforementioned main components is 100 mass%, the Fe ２ O ３ The firing marker according to claim 1 or 2, wherein the content of is 60 to 70 mass%.
4. The firing marker according to claim 3, wherein when the total mass of the main components is 100 mass%, the ZnO content is 18 to 22 mass%.
5. The firing marker according to claim 4, wherein when the total mass of the main components is 100 mass%, the NiO content is 9 to 11 mass%.
6. The firing marker according to claim 5, wherein when the total mass of the main components is 100 mass%, the CuO content is 4 to 5 mass%.