Sealing material and sealing structure

Abstract

The sealing material contains an inorganic component and water, the viscosity of the sealing material at 25 DEG C is 10,000 mPas to 3,50,000 mPas, and the sealing material is foamed at 120 DEG C.

Description

Technical Field

[0001] This disclosure relates to sealing materials and sealing structures. Background Technology

[0002] High-temperature devices such as high-temperature atmosphere furnaces, which have an internal space that allows for controlled atmosphere, are widely used in various fields.

[0003] In such high-temperature devices, the sealing performance of the parts that connect the internal space to the outside environment may sometimes decrease during use. Furthermore, in such cases, it is often necessary to repair the seals while maintaining the high-temperature device at that temperature.

[0004] To carry out so-called in-situ repairs of such high-temperature devices, various sealing materials and sealing methods have been proposed to date (e.g., Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-3313 Summary of the Invention

[0008] In the in-situ repair of high-temperature equipment, it is required that sealing material be placed in the sealing part under high temperature conditions to properly seal the internal space from the outside.

[0009] However, conventional sealing materials sometimes cannot guarantee a sufficient sealing effect. For example, even sealing materials that perform well at room temperature (25°C) may sometimes fail to achieve a tight seal with the wall of the sealing area, such as for sealing areas in high-temperature regions above 300°C.

[0010] The purpose of this disclosure is to provide a sealing material with good sealing performance for the wall surface of a sealing part in a high-temperature region, and a sealing structure using the above-mentioned sealing material.

[0011] This disclosure includes the following methods.

[0012] <1>

[0013] A sealing material comprising inorganic components and moisture.

[0014] The viscosity of the aforementioned sealing material is 10000 mPa•s to 350000 mPa•s at 25°C.

[0015] The above-mentioned sealing material foams at 120°C.

[0016] <2>

[0017] According to the sealing material described in <1>, the inorganic component comprises at least one selected from aluminosilicates and silicates.

[0018] <3>

[0019] According to the sealing material described in <2>, the inorganic component comprises the aforementioned aluminosilicate.

[0020] The ratio of Si atoms to Al atoms in the aforementioned sealing material is 3.0 to 10.0.

[0021] <4>

[0022] According to the sealing material described in <3>, the aforementioned aluminosilicate comprises sodium aluminosilicate.

[0023] <5>

[0024] According to the sealing material described in <2>, the inorganic component comprises the aforementioned aluminosilicate.

[0025] The amount of moisture contained in the sealing material as a whole is 40% to 70% by mass.

[0026] <6>

[0027] According to the sealing material described in <2>, the silicate comprises sodium silicate.

[0028] <7>

[0029] According to any one of <1> to <6>, when the sealing material is prepared by placing the sealing material on a sealing portion at 300°C to form a foamed cured product of the sealing material, the porosity of the foamed cured product is 50% by volume or more.

[0030] <8>

[0031] According to any one of <1> to <7>, when the sealing material is made into a foamed cured product by contacting the sealing material with the surface of a plate at 300°C, the arithmetic mean roughness Ra of the surface of the foamed cured product in contact with the surface is 1 mm or less.

[0032] <9>

[0033] The sealing material according to any one of <1> to <8> is used in a sealing part that isolates the internal space of a high-temperature device from the outside.

[0034] <10>

[0035] A sealing structure is a foamed and cured product of the sealing material described in any one of <1> to <9>.

[0036] <11>

[0037] According to the sealing structure described in <10>, the porosity is 50% by volume or more.

[0038] <12>

[0039] According to <10> or <11>, the sealing structure is provided in the sealing part that isolates the internal space of the high-temperature device from the outside.

[0040] According to this disclosure, a sealing material with good sealing performance for the wall surface of a sealing part in a high-temperature region and a sealing structure using the above-described sealing material can be provided. Attached Figure Description

[0041] Figure 1 This is a schematic cross-sectional view illustrating an example of a sealing structure of the present disclosure formed by placing an example of the sealing material of the present disclosure into the sealing part of a high-temperature device.

[0042] Figure 2 This is a schematic diagram illustrating the configuration of an example of a high-temperature device. Detailed Implementation

[0043] The embodiments of this disclosure will now be described in detail. However, this disclosure is not limited to the embodiments described below. In the embodiments described below, the constituent elements (including element steps, etc.) are not essential unless specifically stated otherwise. The same applies to numerical values ​​and their ranges, which are not limiting to this disclosure.

[0044] In this disclosure, the numerical values ​​recorded before and after “~” in the numerical range represented by “~” are respectively the minimum value and the maximum value.

[0045] In this disclosure, each component may contain multiple substances that conform to the composition. When multiple substances conforming to each component are present in the composition, the proportion of each component, unless otherwise specified, refers to the total proportion of the multiple substances present in the composition.

[0046] In the numerical ranges described in this disclosure in stages, the upper or lower limit of a numerical range can be replaced by the upper or lower limit of other numerical ranges described in stages. Furthermore, the upper or lower limit of a numerical range described in this disclosure can be replaced by the values ​​shown in the embodiments.

[0047] In this disclosure, while embodiments are described with reference to the accompanying drawings, the configuration of these embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in the drawings are conceptual sizes, and the relative sizes between components are not limited thereto.

[0048] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0049] In this disclosure, "sealing material" refers to a material applied to a sealing portion of a high-temperature device or the like for sealing the internal space from the outside. It should be noted that "sealing portion" is the area where sealing material is provided.

[0050] Furthermore, in this disclosure, "sealing structure" refers to a component formed in a high-temperature sealing part of a high-temperature device by providing a "sealing material". Therefore, if a "sealing material" is provided in a high-temperature sealing part of a high-temperature device, a "sealing structure" is formed by that "sealing material".

[0051] [Sealing material]

[0052] One embodiment of the sealing material disclosed herein contains inorganic components and moisture, the viscosity of the sealing material is 10000 mPa·s to 350000 mPa·s at 25°C, and the sealing material foams at 120°C.

[0053] Hereinafter, the viscosity of the sealing material at 25°C will be referred to as "25°C viscosity", and the foaming property at 120°C will be referred to as "high-temperature foaming property".

[0054] As mentioned above, even sealing materials that perform well at room temperature (25°C) may sometimes fail to achieve a tight seal against the wall of the sealing part in high-temperature areas. Hereinafter, the tightness of the seal against the wall of the sealing part in high-temperature areas will be referred to as "high-temperature sealing performance".

[0055] One reason for the difficulty in achieving high-temperature sealing is the Leidenfrost phenomenon. The Leidenfrost phenomenon occurs when a liquid comes into contact with a solid at a temperature above its boiling point, resulting in a layer of vapor generated from the liquid between the solid and the liquid. It is argued that if, due to the Leidenfrost phenomenon, water vapor generated from the sealing material forms between the sealing material and the wall of the sealing part, the sealing performance of the sealing material against the wall of the sealing part is reduced.

[0056] In contrast, the sealing material of this embodiment, by containing inorganic components and moisture, having a viscosity within the aforementioned range at 25°C, and possessing high-temperature foaming properties, is able to suppress the aforementioned Redenfrost phenomenon. The reason for this is not yet clear, but it is speculated as follows.

[0057] It is believed that in sealing materials containing inorganic components and moisture, with a viscosity within the aforementioned range at 25°C, and exhibiting high-temperature foaming properties, the inorganic components and moisture mix to form a gel-like state, trapping the moisture within the sealing material and making it difficult for it to release to the outside. Furthermore, even if the moisture turns into gas when the sealing material's temperature rises, it will still foam within the sealing material, making it difficult for it to release as water vapor to the outside. Therefore, it is speculated that the Redenfrost phenomenon is suppressed, particularly compared to cases where the viscosity at 25°C is below the aforementioned range. Moreover, by suppressing the Redenfrost phenomenon, the high-temperature sealing performance of the sealing material is improved.

[0058] In addition to suppressing the Redenfrost phenomenon, the sealing material of this embodiment also exhibits high conformability to the wall surface of the sealing portion due to its viscosity being within the aforementioned range at 25°C. It is believed that this high conformability to the wall surface of the sealing portion results in improved high-temperature sealing performance compared to cases where the viscosity at 25°C is higher than the aforementioned range.

[0059] Furthermore, the sealing material of this embodiment has high-temperature foaming properties, so even when in contact with the wall surface of the sealing part in a high-temperature area, it can suppress the drying shrinkage of the sealing material that accompanies the reduction of moisture content. Therefore, it is difficult to cause cracks due to drying shrinkage.

[0060] It should be noted that there is no particular limitation on the method for obtaining a sealing material with a viscosity within the above-mentioned range at 25°C and high-temperature foaming properties, and it can be selected according to the type of inorganic components contained in the sealing material. Examples of methods for obtaining a sealing material with a viscosity within the above-mentioned range at 25°C and high-temperature foaming properties include adjusting the stirring conditions during the preparation of the sealing material and adjusting the moisture content of the sealing material.

[0061] <Viscosity at 25℃>

[0062] The viscosity of the sealing material at 25°C is 10,000 mPa·s or higher, and from the viewpoint of improving high-temperature sealing performance, it is preferably 30,000 mPa·s or higher, more preferably 50,000 mPa·s or higher. Furthermore, the viscosity of the sealing material at 25°C is 350,000 mPa·s or lower, and from the viewpoint of improving high-temperature sealing performance, it is preferably 300,000 mPa·s or lower, more preferably 200,000 mPa·s or lower. The viscosity of the sealing material at 25°C is between 10,000 mPa·s and 3,500,000 mPa·s, preferably between 30,000 mPa·s and 300,000 mPa·s, more preferably between 50,000 mPa·s and 200,000 mPa·s.

[0063] The viscosity of the sealing material at 25°C is measured using an E-type viscometer at 25°C. Specifically, an E-type viscometer (e.g., Toki Sangyo Co., Ltd., TV-100E) is used to measure the viscosity at 25°C at a rotation speed of 10 rpm. It should be noted that the sample used for measuring the above-mentioned viscosity at 25°C is the sealing material that has been left to stand at 25°C for more than 24 hours since its preparation and then stirred with a spoon more than 10 times for no more than 5 minutes.

[0064] The reason for using a sealing material that has been left to stand at 25°C for at least 24 hours since its preparation is that the viscosity of a sealing material sometimes changes over time after its preparation. For example, even a sealing material with a viscosity of 10,000 mPa·s to 350,000 mPa·s at 25°C within 10 minutes of its preparation may have a viscosity of less than 10,000 mPa·s at 25°C after being left to stand at 25°C for at least 24 hours. An example of such a sealing material is one that is gel-like immediately after preparation, but whose inorganic components crystallize over time into microparticles, which then disperse in the liquid as micelles, resulting in a viscosity of less than 10,000 mPa·s at 25°C. In contrast, the viscosity of the sealing material of this embodiment at 25°C, i.e., the viscosity at 25°C after being left to stand at 25°C for at least 24 hours since its preparation, is measured. Since this value is within the aforementioned range, it is presumed that this is a sealing material that maintains a gel-like state after being left to stand for at least 24 hours.

[0065] Furthermore, the reason for stirring with a spoon before measuring viscosity is to measure the viscosity of a sealant that is stable in a gel state and the viscosity of a sealant that precipitates as inorganic particles under the same conditions.

[0066] In this embodiment, when the viscosity at 25°C is defined as η, and the viscosity of the sealing material at 25°C within 10 minutes of preparation is defined as η0, from the viewpoint of the storage stability of the sealing material, the viscosity change rate (%) |η0-η|×100 / η0 of the sealing material at 25°C is preferably 40% or less, more preferably 30% or less, even more preferably 20% or less, and particularly preferably 10% or less. Hereinafter, the viscosity change rate (%) |η0-η|×100 / η0 of the sealing material at 25°C will also be referred to as the "viscosity change rate".

[0067] It should be noted that the viscosity η0 of the sealing material at 25°C within 10 minutes of preparation is determined using the same method as the above-mentioned viscosity at 25°C, except that the sealing material within 10 minutes of preparation is used as the sample.

[0068] <High-temperature foaming properties and porosity at 300℃>

[0069] The sealing material of this embodiment has high-temperature foaming properties. High-temperature foaming properties mean that the sealing material foams when heated to 120°C, that is, it produces bubbles.

[0070] Whether a sealing material has high-temperature foaming properties is confirmed as follows. Specifically, a state in which the volume expands and air bubbles are present in its cross-section when held at 120°C for 10 minutes is defined as having "high-temperature foaming properties".

[0071] In the sealing material of this embodiment, from the viewpoint of suppressing the generation of cracks caused by drying shrinkage, the porosity of the foamed cured material formed by providing a sealing portion at 300°C is preferably 50% by volume or more, more preferably 60% by volume or more, and even more preferably 70% by volume or more. Hereinafter, the porosity of the foamed cured material formed by providing a sealing portion at 300°C will also be referred to as "300°C porosity". From the viewpoint of obtaining a sealing structure with high strength, the 300°C porosity of the sealing material is preferably 95% by volume or less, more preferably 90% by volume or less, and even more preferably 80% by volume or less. The 300°C porosity of the sealing material is preferably 50% by volume to 95% by volume, more preferably 60% by volume to 90% by volume, and even more preferably 70% by volume to 80% by volume.

[0072] The porosity of the sealing material at 300℃ was determined as follows.

[0073] Specifically, firstly, in a volume of 500 cm³ heated to 300°C... 3 The sealing material of the test object is placed into the container. The amount of sealing material added is such that the volume of the foamed and cured sealing material will not overflow the container, that is, the volume of the foamed and cured sealing material included in the container. When the volume of the added sealing material is set as V0 and the volume of the obtained foamed and cured material is set as V1, the expansion rate A (%) of the sealing material and the porosity P (%) of the sealing material at 300°C are expressed by the following formulas (1) and (2).

[0074] Equation (1): Expansion rate A (%) = (V1 / V0) × 100

[0075] Equation (2): Porosity P (%) = [(Expansion rate A (%) / Specific gravity of sealing material) - (Mass ratio of solid components (%) / True specific gravity of solid components in sealing material)] × 100 / (Expansion rate A (%) / Specific gravity of sealing material)

[0076] It should be noted that in the above formulas (1) and (2), "specific gravity of sealing material" is a value calculated based on the mass and volume of sealing material, "mass ratio of solid components (%)" is a value expressed as "100 - water content of sealing material (%)", and "true specific gravity of solid components of sealing material" is a value determined by pulverizing the foamed and cured sealing material and using the Archimedes method.

[0077] <300℃Ra>

[0078] In the sealing material of this embodiment, from the viewpoint of improving high-temperature sealing performance, when a foamed cured material is formed by contacting the surface of a plate at 300°C, the arithmetic mean roughness Ra of the surface in contact with the plate is preferably 1 mm or less, more preferably 0.5 mm or less, even more preferably 0.2 mm or less, and particularly preferably 0.1 mm or less. Hereinafter, the arithmetic mean roughness Ra of the surface in contact with the plate when a foamed cured material is formed by contacting the surface of a plate at 300°C will also be referred to as "300°C Ra". A sealing material that suppresses the aforementioned Redenfrost phenomenon, has good conformability to the plate surface, and suppresses the generation of cracks caused by drying shrinkage has a smaller 300°C Ra value. The lower limit of 300°C Ra is not particularly limited; for example, 0.01 mm can be cited. 300°C Ra is preferably 0.01 mm to 1 mm, more preferably 0.01 mm to 0.5 mm, even more preferably 0.01 mm to 0.2 mm, and particularly preferably 0.01 mm to 0.1 mm.

[0079] Ra was measured at 300℃ as follows.

[0080] A plate with an arithmetic mean surface roughness Ra of less than 10 μm was heated to 300°C, and a sealant was directly applied to the surface and maintained for 10 minutes to obtain a foamed cured product. Then, the temperature of the plate was reduced to 25°C, and the foamed cured product was peeled off from the surface of the plate. The arithmetic mean surface roughness Ra of the surface in contact with the plate was measured by the following method.

[0081] There are no particular limitations on the plates used for measuring Ra at 300℃, as long as the arithmetic mean surface roughness Ra is less than 10 μm. Examples include metal plates and ceramic plates.

[0082] The arithmetic mean roughness Ra was measured according to JIS B0601 (1994) as follows.

[0083] A laser microscope (e.g., Keyence VK-X3000) was used as the measuring device to observe the three-dimensional shape of the surface at 100x magnification. Based on the roughness curve obtained from the obtained three-dimensional shape, the arithmetic mean roughness Ra was calculated under the conditions of a reference length of 8 mm and a cutoff value of 8 mm.

[0084] <Composition>

[0085] The sealing material in this embodiment contains at least inorganic components and moisture.

[0086] The inorganic components contained in the sealing material are not particularly limited as long as they enable the overall viscosity of the sealing material at 25°C to be within the aforementioned range. The sealing material may contain only one inorganic component or two or more. Examples of inorganic components include inorganic oxides.

[0087] Specific examples of inorganic components include inorganic acid metal salts such as aluminosilicates, silicates, and polyborates. Among these, aluminosilicates and silicates are preferred from the perspectives of safety, heat resistance, and price, with aluminosilicates being more preferred. Here, "silicate" refers to silicates that do not contain aluminum atoms, that is, silicates other than aluminosilicates.

[0088] Alkali metal salts can be cited as examples of metal salts. Specific examples of alkali metal salts include sodium salts, potassium salts, and lithium salts, among which sodium salts are preferred from the viewpoint of availability. The sealing material preferably contains alkali metal atoms, and more preferably sodium atoms. The sealing material may contain only one type of alkali metal atom or two or more types.

[0089] The amount of water contained in the sealing material is not particularly limited as long as the viscosity of the sealing material at 25°C is within the aforementioned range and the sealing material has high-temperature foaming properties. Hereinafter, the amount of water relative to the total amount of the sealing material will be referred to as the "moisture content". The preferred moisture content of the sealing material varies depending on the type of inorganic components contained in the sealing material. Examples of moisture content in the sealing material include 30% to 70% by mass. From the viewpoint of improving high-temperature sealing performance, the moisture content of the sealing material is preferably 70% by mass or less, more preferably 60% by mass or less. Furthermore, from the viewpoint of improving high-temperature sealing performance, the moisture content of the sealing material is preferably 30% by mass or more, more preferably 35% by mass or more. The moisture content of the sealing material is preferably 30% to 70% by mass, more preferably 35% to 60% by mass.

[0090] By keeping the moisture content of the sealing material below the upper limit mentioned above, the Redenfrost phenomenon can be easily suppressed; by keeping it above the lower limit mentioned above, the sealing part's conformity to the wall surface becomes good.

[0091] The moisture content of the sealing material was determined as follows.

[0092] The weight at which the water content decreased was determined by using a differential thermal balance (Rigaku Corporation TG-8120 Thermo Plus EVO2) to maintain the water content at 150°C for 1 hour.

[0093] The sealing material of this embodiment may contain other components besides inorganic components and moisture, as needed.

[0094] The total content of inorganic components and moisture relative to the overall sealing material is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and can also be 100% by mass.

[0095] In addition, the inorganic components contained in the sealing material preferably include inorganic acid metal salts as described above, more preferably include at least one selected from aluminosilicates, silicates and polyborates, further preferably include at least one selected from aluminosilicates and silicates, particularly preferably include aluminosilicates, and most preferably include sodium aluminosilicate.

[0096] The inorganic components in sealing materials can include inorganic acid metal salts and other inorganic components besides inorganic acid metal salts. Examples of other inorganic components include inorganic oxide particles used for purposes such as adjusting the viscosity of the sealing material, improving workability in high-temperature areas, and increasing the mechanical strength of the foamed and cured product. Examples of inorganic oxide particles include silica, alumina, alumina hydrate, titanium dioxide, zirconium oxide, zeolite, and clay compounds.

[0097] When the inorganic component contained in the sealing material includes inorganic oxide particles, the content of inorganic oxide particles relative to the total inorganic component can be, for example, 20 to 70% by mass.

[0098] The content of inorganic acid metal salt relative to the total inorganic components contained in the sealing material is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, extremely preferably 95% by mass or more, and may also be 100% by mass.

[0099] Hereinafter, as examples of sealing materials in this embodiment, sealing materials containing aluminosilicate as an inorganic component, sealing materials containing silicate as an inorganic component, and sealing materials containing polyborate as an inorganic component will be described.

[0100] <Sealing materials containing aluminosilicates>

[0101] Examples of aluminosilicates include sodium aluminosilicate, potassium aluminosilicate, and lithium aluminosilicate, with sodium aluminosilicate being the preferred choice.

[0102] In sealing materials containing aluminosilicates, from the perspective of improving high-temperature sealing performance, the number of Si atoms N in the sealing material is important. Si With the number of Al atoms N Al The ratio of N Si / N AlPreferred values ​​are 3.0 to 10.0.

[0103] In sealing materials containing aluminosilicates, by ratio N Si / N Al The value is within the above range, thus easily making it a sealing material with a viscosity within the above range at 25°C and high-temperature foaming properties. The reason is not yet clear, but it is speculated that it is because of the difference in N... Si / N Al When the value is within the above range, it is easy to form a mesh structure of inorganic components.

[0104] N Si / N Al The value is preferably 3.0 or higher. Additionally, compared to N... Si / N Al The value is preferably 10.0 or less, more preferably 8.0 or less, further preferably 7.0 or less, even more preferably 5.0 or less, particularly preferably 4.5 or less, and extremely preferably 3.5 or less. (Compared to N) Si / N Al The value is more preferably 3.0 to 7.0, further preferably 3.0 to 5.0, particularly preferably 3.0 to 4.5, and extremely preferably 3.0 to 3.5.

[0105] In sealing materials containing aluminosilicates, from the perspective of improving high-temperature sealing performance, the number of Si atoms N in the sealing material is important. Si The number of atoms N of alkali metal atoms M The ratio of N Si / N M The preferred value is 0.5 to 2.5, more preferably 1.5 to 2.2, and even more preferably 1.6 to 1.8.

[0106] The above ratio N Si / N Al And N Si / N M The value was determined as follows.

[0107] Specifically, after the test sample of the sealing material was pulverized using a mortar, it was measured using a Rigaku ZSX Primus IV fluorescence X-ray analyzer.

[0108] Controlling the above ratio N of sealing materials containing aluminosilicates Si / N Al And N Si / N M There is no particular limitation on the method for determining the value of N. For example, as described later, the N ratio can be controlled by adjusting the mixing ratio of silicate to aluminate in a sealing material containing aluminosilicate, obtained from a mixture of silicate, aluminate, and water. Si / N Al And N Si / NM The value of .

[0109] From the viewpoint of improving high-temperature sealing performance, the moisture content of the sealing material containing aluminosilicate is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. Furthermore, from the viewpoint of improving high-temperature sealing performance, the moisture content of the sealing material containing aluminosilicate is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more.

[0110] The moisture content of the sealing material containing aluminosilicate is preferably 40% to 70% by mass, more preferably 45% to 65% by mass, and even more preferably 50% to 60% by mass.

[0111] The moisture content of aluminosilicate-containing sealant can be controlled, for example, by adjusting the amount of water added to the aluminosilicate-containing sealant obtained from a mixture of silicate, aluminate and water, as described later.

[0112] Sealing materials containing aluminosilicates can be obtained, for example, by mixing silicates, aluminates, and water. The silicates and aluminates may have the same or different types of alkali metal atoms, but the same type is preferred. Sealing materials containing aluminosilicates are preferably those formed by mixing sodium silicate, sodium aluminate, and water.

[0113] In sealing materials containing aluminosilicates, methods for controlling viscosity at 25°C and high-temperature foaming properties include, for example, using a mixer to adjust the stirring speed, stirring time, and mixing ratio of silicate, aluminate, and water during the aforementioned mixing process. It should be noted that, for example, a stirring speed of 500 rpm or more, preferably 3000 rpm or more, is acceptable. There is no particular upper limit to the stirring speed; for example, 50,000 rpm is acceptable. For example, a stirring time of 1 minute or more, preferably 3 minutes or more, is acceptable. There is no particular upper limit to the stirring time; for example, 10 minutes is acceptable.

[0114] <Sealing materials containing silicates>

[0115] Examples of silicates include sodium silicate, potassium silicate, and lithium silicate, with sodium silicate being the preferred choice.

[0116] The term "sealing material containing silicates" refers to a sealing material that contains silicates but does not contain aluminum atoms, i.e., a sealing material that contains silicates but does not contain aluminum silicates.

[0117] From the perspective of improving high-temperature sealing performance, the moisture content of the silicate-containing sealing material is preferably 30% to 50% by mass.

[0118] In silicate-containing sealing materials, when the water content is within the aforementioned range, it is easy to obtain a sealing material with a viscosity within the aforementioned range at 25°C and high-temperature foaming properties. The reason for this is not yet clear, but it is speculated that it is because when the water content is within the aforementioned range, it is easy to form a mesh structure of inorganic components.

[0119] The moisture content of the silicate-containing sealing material is preferably 50% by mass or less, more preferably 45% by mass or less. Furthermore, the moisture content of the silicate-containing sealing material is preferably 30% by mass or more, more preferably 35% by mass or more. The moisture content of the silicate-containing sealing material is more preferably 35% to 40% by mass.

[0120] In sealing materials containing silicates, methods for controlling moisture content include, for example, mixing powdered silicates with a specified amount of moisture, and using microwave heating to uniformly remove moisture from commercially available silicates (liquid) to form the desired composition.

[0121] In silicate-containing sealing materials, from the viewpoint of foaming and defoaming properties, the number of Si atoms N contained in the sealing material is... Si The number of atoms N of alkali metal atoms M The ratio of N Si / N M The preferred value is 1.5 to 2.0.

[0122] N Si / N M The value can be determined using the methods described above.

[0123] Controlling the above ratio N of the sealing material containing silicates Si / N M There are no particular limitations on the method for determining the value; however, examples can be given of methods for selecting the type of silicate used.

[0124] Sealing materials containing silicates can be obtained, for example, by mixing silicates and water and controlling the water content using the methods described above.

[0125] <Sealing materials containing polyborate>

[0126] Examples of polyborates include sodium polyborate, potassium polyborate, and lithium polyborate, with sodium polyborate being the preferred choice.

[0127] In sealing materials containing polyborates, one method for controlling moisture content is, for example, to increase the solubility of boric acid in water by mixing it with sodium borate and dissolving it in water, thereby controlling the moisture concentration.

[0128] In sealing materials containing polyborates, the number of boron atoms N in the sealing material is... B The number of atoms N of alkali metal atomsM The ratio of N B / N M The value can be obtained by using the ratio N mentioned above. Si / N M The value is determined using the same method.

[0129] Controlling the above ratio N of sealing materials containing polyborate B / N M There are no particular limitations on the method for determining the value; however, examples can be given for selecting the type of polyborate used.

[0130] Sealing materials containing polyborates can be obtained, for example, by mixing polyborates with water and controlling the water content using the methods described above.

[0131] <Uses>

[0132] The sealing material of this embodiment is used, for example, in sealing portions that isolate the internal space of a high-temperature device from the outside environment. The sealing material of this embodiment also provides good sealing performance in high-temperature areas. The temperature of the sealing portion can be, for example, 150°C to 600°C, 200°C to 600°C, 300°C to 600°C, or 400°C to 600°C. It should be noted that the temperature of the sealing portion refers to the temperature measured on the wall surface of the sealing portion using a thermometer.

[0133] [Sealed structure]

[0134] One embodiment of the sealing structure disclosed herein is a foamed and cured product of the sealing material of the above-described embodiments.

[0135] The sealing structure of this embodiment is provided, for example, in a sealing part that isolates the internal space of the high-temperature device from the outside world, and is obtained by providing the above-mentioned sealing material in the sealing part of the high-temperature area and making it into a foamed and cured material.

[0136] From the viewpoint of suppressing crack formation caused by drying shrinkage during the manufacturing process, the porosity of the sealing structure is preferably 50% by volume or more, more preferably 60% by volume or more, and even more preferably 70% by volume or more. From the viewpoint of strength, the porosity of the sealing structure is preferably 95% by volume or less, more preferably 90% by volume or less, and even more preferably 85% by volume or less.

[0137] Knowing the volume of the sealing material before obtaining the sealing structure, and setting the volume of the sealing material as V0 and the volume of the sealing structure as V1, the porosity of the sealing structure is calculated using the same method as the porosity of the sealing material at 300°C.

[0138] On the other hand, without knowing the volume of the sealing material before obtaining the sealing structure, let ρ be the true specific gravity of the solid component of the sealing structure, M (g) be the mass of the sealing structure, and V (cm³) be the apparent volume of the sealing structure. 3 When ), the porosity Ps (%) of the sealing structure is expressed by the following formula (3).

[0139] Equation (3): Porosity Ps (%) = (M / (ρ × V)) × 100

[0140] It should be noted that in the above formula (3), ρ is the value calculated using the pulverized material of the sealed structure and based on the volume and weight obtained by Archimedes' method, and V is the value determined by Archimedes' method.

[0141] The apparent density of a sealed structure can be , for example, 0.8 g / cm³. 3 From the viewpoint of suppressing cracks during the manufacturing process, 0.7 g / cm³ is preferred. 3 Below, 0.5 g / cm³ is more preferred. 3 From a strength point of view, the apparent density of the sealing structure is preferably 0.1 g / cm³. 3 More preferably 0.2 g / cm³ 3 The above is further optimized to 0.3 g / cm³. 3 above.

[0142] It should be noted that the apparent density of the sealing structure is obtained by dividing the mass of the sealing structure by its apparent volume.

[0143] Hereinafter, an example of a sealing structure of this embodiment, which is provided in a sealing part that isolates the internal space of the high-temperature device from the outside world, and an example of a high-temperature device will be described.

[0144] Figure 1 This is a cross-sectional view schematically showing an example of a sealing structure formed in the sealing part of this embodiment of a high-temperature device.

[0145] like Figure 1 As shown, the sealing structure 100 is disposed in the sealing part 20 that blocks the gap 15 of the high-temperature device 10.

[0146] More specifically, the high-temperature device 10 has a first wall component 30 and a second wall component 31, which together form an internal space 40 within the high-temperature device 10. However, a gap 15 exists between the first wall component 30 and the second wall component 31. To seal this gap 15, a sealing component 42 is filled into the gap 15. This constitutes a sealing portion 20, isolating the internal space 40 from the outside environment.

[0147] However, for example, if the high-temperature device 10 is used for a long time, the sealing component 42 may deteriorate, and its sealing performance may decrease. In such cases, when the high-temperature device 10 is in use, that is, when the sealing part 20 is at a high temperature, it may be necessary to repair the sealing component 42.

[0148] The sealing structure 100 is provided for such in-situ repair. That is, by forming the sealing structure 100 in the sealing part 20, the sealing performance of the high-temperature device 10 can be maintained.

[0149] The temperature of the sealing portion 20 of the sealing structure 100 varies depending on the high-temperature device 10. For example, the temperature of the sealing portion 20 of the sealing structure 100 can be in the range of 150°C to 600°C.

[0150] The first wall component 30 and the second wall component 31 of the sealing part 20, which is provided with the sealing structure 100, can be made of any material as long as they are heat-resistant materials such as metal (e.g., heat-resistant metal) and ceramic (e.g., refractory brick).

[0151] The sealing structure 100 is formed by placing the sealing material of the above-described embodiment on the sealing part 20 of the high-temperature device 10, thereby foaming and curing the sealing material.

[0152] There is no particular limitation on the method of applying the sealing material to the sealing portion 20 of the high-temperature device 10. For example, a method of filling the sealing portion 20 of the high-temperature device 10 with the sealing material using a trowel or scraper can be cited. It should be noted that, in the case of a high temperature in the sealing portion 20, for safety reasons, a method that can apply the sealing material from a distance, such as a mortar injector or a spray application method, can be used.

[0153] The high-temperature device 10 is not limited to this, such as various kilns including coal coking ovens, iron ore blast furnaces, glass melting furnaces and glass forming furnaces.

[0154] Figure 2 The configuration of a high-temperature device 210, which is an example of a high-temperature device 10, is schematically shown.

[0155] Figure 2 The high-temperature apparatus 210 shown includes a metal container 220 and an electric furnace 230 that houses the metal container 220.

[0156] The metal container 220 is made of stainless steel and has a generally rectangular shape. One side of the metal container 220 is open, and this opening is rectangular in shape, measuring 150mm × 20mm. It should be noted that the internal volume of the metal container 220 is approximately 10L.

[0157] The metal container 220 is disposed within the electric furnace 230 with an opening protruding outward from the furnace 230. The length of the protrusion 226 protruding from the furnace 230 is approximately 10 mm. It should be noted that a portion of the metal container 220 is provided with another opening, which connects to an air buffer tank 240.

[0158] When setting the sealing material, the electric furnace is heated to approximately 550°C. This heats the protrusion 226 of the metal container 220 to approximately 350°C.

[0159] It should be noted that the sealing material is installed as follows, for example.

[0160] Sealing material is filled into the metal container 220 from near the protrusion 226. Thus, the protrusion 226, with sealing material 250, forms a sealing structure that seals the opening. The depth of the sealing material 250 is 20 mm from the front end of the protrusion 226.

[0161] Ten minutes after filling with sealing material 250, the buffer tank 240 is opened, and air is supplied to the interior of the metal container 220. The opening is sealed by a sealing structure, thereby enabling the pressure inside the metal container 220 to reach, for example, 10000 Pa.

[0162] Example

[0163] The embodiments of this disclosure will be described in detail below, but the embodiments of this disclosure are not limited to these.

[0164] It should be noted that in the following description, examples A3-A8, A13-A17 and B5-B8 are examples, and examples A1-A2, A9-A12, A18-A20, B1-B4 and B9 are comparative examples.

[0165] [Example A]

[0166] <Preparation of Sealing Materials>

[0167] (Examples A1~A19)

[0168] Sodium silicate (manufactured by Nippon Chemical Industry Co., Ltd., water glass No. 1 and No. 3), sodium aluminate (manufactured by Hokuriku Chemical Industry Co., Ltd., sodium aluminate powder) and water were mixed and stirred for 3 minutes at 3000 rpm using a mixer (manufactured by YAMATO Scientific, trade name: Cutter Mixer R-15E) to obtain sealing materials of Examples A1 to A19 respectively.

[0169] It should be noted that the amounts of sodium silicate, sodium aluminate, and water added are such that the composition ratio (mass%) of SiO2, Al2O3, Na2O, and H2O is as shown in Tables 1 and 2. The composition ratio (mass%) of H2O in Tables 1 and 2 corresponds to the water content of the sealing material.

[0170] The number of Si atoms N contained in the sealing material Si With the number of Al atoms N Al The ratio of N Si / N Al They are shown together in Tables 1 and 2.

[0171] (Example A20)

[0172] By changing the stirring speed to 1500 rpm and the stirring time from 3 minutes to 1 minute, the sealing material of Example A20 was obtained in the same manner as in Example A7.

[0173] The composition ratio (mass%) of SiO2, Al2O3, Na2O and H2O and the ratio of N Si / N Al They are shown together in Table 2.

[0174] <Determination of Sealing Materials>

[0175] According to the above method, the viscosity η of the sealing material at 25°C and the viscosity η0 of the sealing material at 25°C within 10 minutes of preparation were measured, and the viscosity change rate (%) was calculated as: |η0-η|×100 / η0. The results are shown in Tables 1 and 2.

[0176] Based on the above method, it was confirmed whether the sealing material has high-temperature foaming properties (i.e., whether it has high-temperature foaming properties). The results are shown in Tables 1 and 2.

[0177] According to the method described above, the expansion rate of the sealing material and the porosity of the foamed cured material (i.e., the porosity at 300°C) were measured when the sealing part was set at 300°C to form a foamed cured material. It should be noted that the porosity at 300°C was calculated with the specific gravity of the sealing material being 1.5 and the true specific gravity of the solid component of the sealing material being 1.8. The results are shown in Tables 1 and 2.

[0178] <Evaluation of Sealing Materials and Determination of Sealing Structures>

[0179] According to the method described above, the arithmetic mean roughness Ra (i.e., 300°C Ra) of the surface in contact with the board when a foamed cured material is formed by contacting the surface of a board at 300°C is measured, thereby evaluating the high-temperature adhesion. A stainless steel board with an arithmetic mean surface roughness Ra of 10 μm was used as the board. The results are shown in Tables 1 and 2. The smaller the value of 300°C Ra, the higher the high-temperature adhesion.

[0180] In addition, the surface in contact with the board of the foamed and cured material obtained by measuring Ra at 300℃ was observed using a magnifying glass (magnification ×10) to confirm whether cracks were present. The results are shown in Tables 1-2.

[0181] It should be noted that the sealant materials in Examples A3 to A8 and A13 to A17 have good workability, with the sealant materials in Examples A7 and A15 having particularly good workability.

[0182] [Table 1]

[0183]

[0184] [Table 2]

[0185]

[0186] As shown in Tables 1-2, the sealing materials of Examples A3-A8 and A13-A17 have higher high-temperature sealing performance compared with the sealing materials of Examples A1-A2, A9-A12 and A18-A20.

[0187] [Example B]

[0188] <Preparation of Sealing Materials>

[0189] (Examples B1~B9)

[0190] Sodium silicate (manufactured by Nippon Chemical Industry Co., Ltd., including powdered sodium silicate and sodium silicate No. 1 and No. 3) was mixed with water and stirred for 3 minutes at 3000 rpm using a mixer (manufactured by YAMATO Scientific, trade name: Cutter Mixer R-15E). After that, a drying treatment (microwave heating) was applied to obtain the sealing materials of Examples B1 to B9.

[0191] It should be noted that the drying process ensures the moisture content of the sealing material is as shown in Table 3 for the H2O composition ratio (mass %). The composition ratio (mass %) of SiO2, Na2O, and H2O, as well as the number of Si atoms N, are... Si The number of sodium atoms N Na The ratio of N Si / N Na They are shown together in Table 3.

[0192] <Determination of Sealing Materials>

[0193] Similar to Example A1, the viscosity η at 25°C, the viscosity η0 at 25°C within 10 minutes of the preparation of the sealing material, the viscosity change rate (%), the presence or absence of high-temperature foaming, and the porosity at 300°C were measured. It should be noted that the porosity at 300°C was calculated using measured data of the weight and apparent volume of the sealing structure and the true specific gravity of the solid component of the sealing material (1.5). The results are shown in Table 3.

[0194] <Evaluation of Sealing Materials and Determination of Sealing Structures>

[0195] Similar to Example A1, the high-temperature sealing performance was evaluated by measuring Ra at 300℃.

[0196] In addition, the presence or absence of cracks was confirmed in the same manner as in Example A1. The results are shown in Table 3.

[0197] In addition, in Example B7, the apparent density of the foamed cured material, i.e., the sealed structure, obtained by measuring Ra at 300°C, was determined using the method described above, and the result was 0.42 g / cm³. 3 .

[0198] It should be noted that the sealing materials in Examples B5 to B8 have good workability, with the sealing material in Example B7 having particularly good workability.

[0199] [Table 3]

[0200]

[0201] As shown in Table 3, the sealing materials of Examples B5 to B8 have higher high-temperature sealing performance compared with the sealing materials of Examples B1 to B4 and B9.

[0202] It should be noted that the sealing materials in Examples B5 to B8 exhibit good workability.

[0203] The entire disclosure of Japanese Patent Application No. 2023-067238, filed on April 17, 2023, is incorporated herein by reference. Furthermore, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as those specifically described herein.

[0204] Symbol Explanation

[0205] 10, 210 High Temperature Device

[0206] 15 gaps

[0207] 20 Sealing section

[0208] 30 First wall component

[0209] 31 Second wall component

[0210] 40 Interior Space

[0211] 42 Sealing components

[0212] 100 Sealed Structure

[0213] 220 Metal Containers

[0214] 226 Protrusion

[0215] 230 Electric Furnace

[0216] 240 Buffer Tank

[0217] 250 Sealing material (sealing structure)

Claims

1. A sealing material comprising inorganic components and moisture, The viscosity of the sealing material is 10000 mPa•s to 350000 mPa•s at 25°C. The sealing material is foamed at 120°C.

2. The sealing material according to claim 1, wherein, The inorganic component includes at least one selected from aluminosilicates and silicates.

3. The sealing material according to claim 2, wherein, The inorganic component includes the aluminum silicate. The ratio of Si atoms to Al atoms in the sealing material is 3.0 to 10.

0.

4. The sealing material according to claim 3, wherein, The aluminosilicate contains sodium aluminosilicate.

5. The sealing material according to claim 2, wherein, The inorganic component includes the aluminum silicate. The amount of water contained in the sealing material relative to the total sealing material is 40% to 70% by mass.

6. The sealing material according to claim 2, wherein, The silicate comprises sodium silicate.

7. The sealing material according to claim 1, wherein, When the sealing material is placed in a sealing section at 300°C to form a foamed cured product of the sealing material, the porosity of the foamed cured product is 50% by volume or more.

8. The sealing material according to claim 1, wherein, When a foamed cured product of the sealing material is made by contacting the sealing material with the surface of a plate at 300°C, the arithmetic mean roughness Ra of the surface of the foamed cured product in contact with the surface is less than 1 mm.

9. The sealing material according to claim 1, used in a sealing part that isolates the internal space of a high-temperature device from the outside.

10. A sealing structure, which is a foamed and cured product of the sealing material according to any one of claims 1 to 9.

11. The sealing structure according to claim 10, wherein, The porosity is above 50% by volume.

12. The sealing structure according to claim 10, wherein, It is located in a sealed section that isolates the internal space of the high-temperature device from the outside world.

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