Insulation

Abstract

To provide a heat insulator excellent in durability.SOLUTION: A heat insulator having a heat insulating member is equipped with a base material including carbon fibers, and a pyrolytic carbon layer including pyrolytic carbon, which is formed on a surface of the base material. The heat insulating member has a cylindrical shape having an inner space storing a heating body. The heat insulating member has a first main surface that is an outer peripheral surface on the heating body side, a second main surface that is an outer peripheral surface on the opposite side to the heating body, and an end surface that connects the first main surface and the second main surface. An exposing portion in which the pyrolytic carbon layer is not formed on the surface of the base material exists in at least one place selected from a group composed of the end surface of the heat insulator, an area where length from the end surface of the first main surface of the heat insulating member is up to 20% of the heat insulating member, and the second main surface of the heat insulating member.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This invention relates to thermal insulation materials. [Background technology]

[0002] Insulation materials made from carbon fiber are widely used as insulation materials for high-temperature furnaces, such as single-crystal pulling equipment and ceramic sintering furnaces, due to their high heat resistance and excellent insulation performance.

[0003] Insulation materials using carbon fibers are widely used in the form of highly porous felt and molded bodies to suppress heat transfer through the carbon fibers. Generally, felt is deformable and is used as a component to fill empty spaces or as insulation material to surround other parts. On the other hand, molded bodies have high shape retention and are processed into a predetermined shape and used as insulation parts. Furthermore, felt can also be used as an insulation part with good shape retention by compressing it and fixing it with a binder.

[0004] Insulation materials using carbon fibers can experience fiber shedding due to oxidation and mechanical friction within the furnace, potentially generating particles. Furthermore, such defects can lead to a decrease in their heat-insulating properties against radiation.

[0005] To solve these problems, Patent Document 1 describes a bulk density of 0.1 to 0.4 g / cm³. 3 Carbonaceous insulating material and bulk density 0.3~2.0 g / cm³ 3 In a composite carbonaceous insulation material having a carbonaceous protective layer and a pyrolysis carbon film having a higher bulk density than the carbonaceous protective layer, it is disclosed that by bonding the carbonaceous protective layer to at least a portion of the surface of a carbonaceous insulation member to form a joint, and forming a pyrolysis carbon film layer on at least the surface of the carbonaceous insulation member on the surface of the joint, wear, deterioration, and powdering of carbon fibers during use are suppressed, and a composite carbonaceous insulation material with excellent thermal insulation properties is obtained.

[0006] The pyrolysis carbon film described in Patent Document 1 exhibits excellent gas barrier properties. However, gas may be present between the carbon fibers that make up the insulating material, and when this gas expands due to heating or other factors, the insulating material covered on the surface with the pyrolysis carbon film has nowhere for the expanded gas to escape, which can destroy the pyrolysis carbon film.

[0007] Patent Document 2 discloses that in an insulating material for a single crystal pulling apparatus, a coating made of pyrolysis carbon is formed on 5 to 95% of the total surface area of ​​the carbonaceous fiber molded body in order to promote the degassing of gas contained in the carbonaceous fiber molded body and to expel the gas from the inside in a short time. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-327441 [Patent Document 2] Japanese Patent Application Publication No. 11-228281 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, Patent Document 2 only discloses forming a film made of pyrolysis carbon on 5 to 95% of the total surface area. In other words, Patent Document 2 does not disclose anything about where to place the areas where the pyrolysis carbon film is not formed, and depending on the location of the areas where the pyrolysis carbon film is not formed, there was a problem that it was not possible to prevent the reaction between the gas generated in the heating furnace and the carbonaceous fiber molded body. As a result, it was difficult to prevent the deterioration and wear of the insulation material.

[0010] This invention was made to solve the above-mentioned problems, and the object of this invention is to provide a highly durable thermal insulation material. [Means for solving the problem]

[0011] The present invention provides a thermal insulation material comprising a thermal insulation member comprising a base material containing carbon fibers and a pyrolysis carbon layer formed on the surface of the base material, wherein the thermal insulation member has a cylindrical shape with an internal space for housing a heating element, the thermal insulation member has a first main surface which is the outer peripheral surface on the heating element side, a second main surface which is the outer peripheral surface on the side opposite to the heating element, and an end surface connecting the first main surface and the second main surface, and an exposed portion where the pyrolysis carbon layer is not formed on the surface of the base material exists at least one location selected from the group consisting of the end surface of the thermal insulation member, a region of the first main surface of the thermal insulation member whose length from the end surface is up to 20% of the thermal insulation member, and the second main surface of the thermal insulation member.

[0012] The thermal insulation material of the present invention has an exposed portion on the surface of the base material in which the pyrolysis carbon layer is not formed, at least one location selected from the group consisting of the end face of the thermal insulation member, the region of the first main surface of the thermal insulation member whose length from the end face is up to 20% of the length of the thermal insulation member, and the second main surface of the thermal insulation member. If the exposed portion is formed at at least one location selected from the group consisting of the end face of the insulating member, the region of the first main surface of the insulating member from the end face up to 20% of the length of the insulating member, and the second main surface of the insulating member, it is possible to prevent the destruction of the pyrolysis carbon layer by degassing of the insulating material while maintaining the barrier (also called gas barrier) between the gas generated in the heating furnace and the substrate containing carbon fibers.

[0013] In the thermal insulation material of the present invention, it is preferable that the exposed portion is located on the end face and / or the second main surface of the thermal insulation member. If the exposed portion is located on the end face and / or second main surface of the insulating material, the possibility of contact between the gas generated in the heating furnace and the substrate containing carbon fibers can be further reduced.

[0014] In the thermal insulation material of the present invention, it is preferable that the exposed portion is located in a region of the second main surface of the thermal insulation member in which the length from the end face is up to 20% of the length of the thermal insulation member. In the region of the second main surface where the length from the end face is up to 20% of the length of the heat insulating member, an exposed portion is likely to be formed.

[0015] In the heat insulating material of the present invention, the ratio of the area of the exposed portion to the total surface area of the heat insulating member is preferably 1% to 4.9%. When the ratio of the area of the exposed portion to the total surface area of the heat insulating member falls within the above range, sufficient gas barrier properties can be exhibited, and the pyrolytic carbon layer can be prevented from being destroyed by degassing of the heat insulating material.

[0016] In the heat insulating material of the present invention, the pyrolytic carbon layer preferably has a thickness of 2 µm to 60 µm. When the thickness of the pyrolytic carbon layer is 2 µm to 60 µm, both excellent gas barrier properties and radiant heat barrier properties can be achieved.

[0017] In the heat insulating material of the present invention, the base material is preferably a needle mat of the carbon fibers or a paper-made product of the carbon fibers. Carbon fiber needle mats and carbon fiber paper-made products are composed of randomly arranged carbon fibers, so they can exhibit high heat insulating properties, and are particularly suitable as base materials constituting the heat insulating material of the present invention.

[0018] In the heat insulating material of the present invention, the average fiber length of the carbon fibers is preferably 2 mm to 8 mm. When the average fiber length of the carbon fibers falls within the above range, the strength of the heat insulating material is easily increased. Furthermore, since carbon fibers are less likely to be oriented, when used in an induction heating furnace, heat generation due to induction heating can be minimized.

[0019] In the heat insulating material of the present invention, it is preferable that a base layer containing carbon-based particles between carbon fibers is further provided between the base material and the pyrolytic carbon layer. When the heat insulating material of the present invention has the above-mentioned base layer, the pyrolytic carbon layer can be stably held by bonding with the pyrolytic carbon layer on the surface.

[0020] In the thermal insulation material of the present invention, it is preferable that the carbon fibers are exposed on the surface of the substrate layer. When carbon fibers are exposed on the surface of the underlying layer, the pyrolysis carbon layer directly bonds with the carbon fibers, thereby increasing the bonding strength between the underlying layer and the pyrolysis carbon layer, and preventing delamination between the layers.

[0021] In the thermal insulation material of the present invention, it is preferable that the carbon-based particles and carbon fibers of the base layer are joined to each other with a carbon-based adhesive. When the carbon-based particles and carbon fibers that make up the base layer are bonded to each other with a carbon-based adhesive, the base layer becomes stronger, and the bonding strength with the pyrolysis carbon layer increases.

[0022] In the thermal insulation material of the present invention, it is preferable that the carbon-based particles are at least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fibers. At least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fiber particles has low impurity content and is the same carbon-based material as the carbon fibers and pyrolysis carbon layer that constitute the insulation material, thus providing high durability at high temperatures.

[0023] In the thermal insulation material of the present invention, the carbon-based particles preferably have an average particle diameter of 10 nm to 500 μm. When the average particle size of carbon-based particles is between 10 nm and 500 μm, a thin underlayer can be formed in the gaps between the carbon fibers, ensuring a high level of bonding between the carbon fibers and the pyrolysis carbon layer in the insulation material. Furthermore, it prevents the underlayer from becoming too thick, which can lead to high thermal conductivity.

[0024] In the thermal insulation material of the present invention, the above-mentioned base layer is preferably 10 μm to 1000 μm thick. If the thickness of the underlayment layer is 1000 μm or less, the decrease in thermal insulation performance can be suppressed. If the thickness of the underlayer is 10 μm or more, the generation of particles due to the degradation of carbon fibers can be sufficiently suppressed.

[0025] The thermal insulation material of the present invention preferably further comprises a cylindrical molded body made of carbon fiber that covers the outer surface of the thermal insulation member. The thermal insulation performance of the present invention can be further enhanced if the thermal insulation material further includes a cylindrical molded body made of carbon fiber that covers the outer surface of the thermal insulation member.

[0026] In the thermal insulation material of the present invention, it is preferable that the thermal insulation member and the molded body are in contact with each other in a manner that allows them to be separated. When the insulation material and the molded body are in contact in a way that allows them to be separated from each other, only the insulation material can be replaced if it deteriorates or wears out. This reduces the time required to replace the insulation material and also reduces the amount of insulation material that needs to be replaced. Consequently, the cost of replacing the insulation material can be reduced. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a schematic perspective view showing an example of the thermal insulation material of the present invention. [Figure 2] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 3 is a magnified view of the area enclosed by the dashed line in Figure 2. [Figure 4] Figure 4 is a schematic, partially cutaway perspective cross-sectional view showing an example of a heating device constructed using the thermal insulation material of the present invention. [Figure 5] Figure 5 is a magnified view of the area enclosed by the dashed line in Figure 4. [Figure 6] Figure 6 is a schematic cross-sectional view showing another example of the thermal insulation material of the present invention. [Figure 7] Figure 7 is a schematic cross-sectional view showing yet another example of the thermal insulation material of the present invention. [Figure 8] Figure 8 is a schematic cross-sectional view showing yet another example of the thermal insulation material of the present invention. [Figure 9]Figure 9 is a photograph of the surface of the insulation material related to Comparative Example 1 after the wear test. [Modes for carrying out the invention]

[0028] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be modified and applied as appropriate without altering the essence of the invention.

[0029] [Insulation material] The present invention provides a thermal insulation material comprising a thermal insulation member comprising a base material containing carbon fibers and a pyrolysis carbon layer formed on the surface of the base material, wherein the thermal insulation member has a cylindrical shape with an internal space for housing a heating element, the thermal insulation member has a first main surface which is the outer peripheral surface on the heating element side, a second main surface which is the outer peripheral surface on the side opposite to the heating element, and an end surface connecting the first main surface and the second main surface, and an exposed portion where the pyrolysis carbon layer is not formed on the surface of the base material exists at least one location selected from the group consisting of the end surface of the thermal insulation member, a region of the first main surface of the thermal insulation member whose length from the end surface is up to 20% of the thermal insulation member, and the second main surface of the thermal insulation member.

[0030] (Insulation material) The thermal insulation member comprises a base material containing carbon fibers and a pyrolysis carbon layer formed on the surface of the base material, which contains pyrolysis carbon.

[0031] The insulating material is cylindrical in shape, having an internal space for housing the heat-generating element. The heat insulating member has a first main surface which is the outer surface on the side facing the heat-generating element, a second main surface which is the outer surface on the side opposite to the heat-generating element, and an end surface which connects the first main surface and the second main surface.

[0032] (base material) The average fiber diameter of the carbon fibers constituting the base material is preferably 1 μm to 20 μm. If the average fiber diameter of the carbon fibers is 20 μm or less, the effect of conductive heat transfer by the carbon fibers themselves can be suppressed. Furthermore, if the average fiber diameter of the carbon fibers is 1 μm or more, excellent light shielding properties are achieved, and radiative heat transfer can be suppressed.

[0033] The average fiber length of the carbon fibers is preferably between 2 mm and 10,000 mm. Furthermore, the average fiber length of the carbon fibers may be 2mm to 8mm, or 10mm to 10,000mm.

[0034] The carbon fibers used can be either pitch-based or PAN-based, and can be either graphite-based or carbonaceous.

[0035] The base material is preferably a carbon fiber needle mat or a carbon fiber papermaking body. Because carbon fiber needle mats and carbon fiber papermaking materials are composed of randomly arranged carbon fibers, they can exhibit high thermal insulation properties and are particularly suitable as base materials for thermal insulation components.

[0036] When the base material is a carbon fiber needle mat, the average fiber length of the carbon fibers is preferably 10 mm to 10,000 mm. When the base material is a carbon fiber papermaking body, the average fiber length of the carbon fibers is preferably 2 mm to 8 mm.

[0037] (Thermolytic carbon layer) A layer of pyrolysis carbon is formed on the surface of the substrate containing carbon fibers. The pyrolysis carbon layer is a layer containing pyrolysis carbon. By forming a pyrolysis carbon layer on the surface of the substrate, gas barrier properties and radiant heat barrier properties can be improved. Furthermore, whether or not a pyrolysis carbon layer is formed on the surface of the substrate can be confirmed by observing the cross-section of the insulating material with a polarizing microscope or the like.

[0038] The thickness of the pyrolysis carbon layer is not particularly limited, but it is preferably between 2 μm and 60 μm. The thickness of the pyrolysis carbon layer can be determined by observing the cross-section of the insulating material with a polarizing microscope or similar device.

[0039] (base layer) The thermal insulation material may also have a base layer containing carbon-based particles between the carbon fibers, between the base material and the pyrolysis carbon layer. Furthermore, the carbon fibers that make up the underlayer are the same as the carbon fibers that make up the base material.

[0040] The thickness of the underlayer is not particularly limited, but is preferably between 10 μm and 1000 μm. If the thickness of the underlayment layer is 1000 μm or less, the decrease in thermal insulation performance can be suppressed. If the thickness of the sublayer is 10 μm or more, sufficient bonding strength between the sublayer and the pyrolysis carbon layer can be ensured.

[0041] The carbon-based particles are preferably at least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fiber particles. At least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fiber particles has low impurity content and is the same carbon-based material as the carbon fibers and pyrolysis carbon layer that constitute the insulation material, thus providing high durability at high temperatures.

[0042] Glassy carbon particles are made by pulverizing non-graphitizable carbon, such as carbides of phenolic resins. Particles obtained by crushing carbon fibers are also called milled carbon fibers. The average fiber length of milled carbon fibers is preferably, for example, 20 μm to 500 μm.

[0043] The carbon-based particles preferably have an average particle diameter of 10 nm to 500 μm. When the average particle size of carbon-based particles is between 10 nm and 500 μm, a thin underlayer can be formed in the gaps between the carbon fibers, ensuring a high level of bonding between the carbon fibers and the pyrolysis carbon layer in the insulation material. Furthermore, it prevents the underlayer from becoming too thick, which can lead to high thermal conductivity.

[0044] It is preferable that the carbon-based particles and carbon fibers are joined to each other with a carbon-based adhesive. When the carbon-based particles and carbon fibers that make up the base layer are bonded to each other with a carbon-based adhesive, the base layer becomes stronger, and the bonding strength with the pyrolysis carbon layer increases.

[0045] Carbon-based adhesives are formed when an organic binder is carbonized by heating in a non-oxidizing atmosphere. Further details will be provided later.

[0046] It is preferable that carbon fibers are exposed on the surface of the underlying layer. When carbon fibers are exposed on the surface of the underlying layer, the pyrolysis carbon layer directly bonds with the carbon fibers, thereby increasing the bonding strength between the underlying layer and the pyrolysis carbon layer, and preventing delamination between the layers.

[0047] (Exposed part) The pyrolysis carbon layer is formed on almost the entire surface of the substrate, but there are some exposed areas on the substrate surface where the pyrolysis carbon layer is not formed. In the exposed areas, the base material may be exposed, or the underlying layer may be exposed.

[0048] The exposed portion is located in at least one of the following locations (1) to (3). (1) End face of the heat insulating member (2) The area of ​​the first main surface of the insulating material that extends up to 20% of the length from the end face of the insulating material. (3) Second main surface of the thermal insulation member Furthermore, no exposed areas are formed in regions other than those described in (1) to (3) above.

[0049] In other words, the exposed portion exists in at least one location selected from the group consisting of the end face of the thermal insulation member, the region of the first main surface of the thermal insulation member from the end face up to 20% of the length of the thermal insulation member, and the second main surface of the thermal insulation member, and there are no exposed portions in any other region. If an exposed portion exists in at least one of the locations described in (1) to (3) above, it is possible to prevent the destruction of the thermal decomposition carbon layer by degassing of the insulation material while maintaining the gas barrier properties of the insulation material.

[0050] The exposed portion is preferably located in (1) and / or (3) below. (1) End face of the heat insulating member (3) Second main surface of the thermal insulation member In this case, no exposed portions are formed in areas other than those described in (1) and (3) above.

[0051] In other words, it is preferable that the exposed portion is located on the end face of the heat insulating member and / or on the second main surface of the heat insulating member, and that there is no exposed portion in any other area. If the exposed portion is located on the end face and / or second main surface of the insulating material, the possibility of contact between the gas generated in the heating furnace and the substrate containing carbon fibers can be further reduced.

[0052] The above (3) is more preferably (3') below. (3') The region of the second main surface of the insulating member in which the length from the end face is up to 20% of the length of the insulating member. Exposed areas are likely to form in the region of the second main surface of the thermal insulation member where the length from the end face is up to 20% of the length of the thermal insulation member.

[0053] The ratio of the exposed area to the total surface area of ​​the thermal insulation material is preferably 1% to 4.9%. When the ratio of the exposed area to the total surface area of ​​the insulating material is within the above range, it is possible to prevent the destruction of the thermally decomposed carbon layer due to degassing of the insulating material while maintaining sufficient gas barrier properties. The total surface area of ​​the insulating material is the sum of the surface areas of the first main surface, the second main surface, and the end surface of the insulating material.

[0054] The exposed portion may be provided at only one location on the insulating material, or at multiple locations. However, from the viewpoint of efficiently degassing the insulating material, it is preferable to have multiple exposed portions. If exposed areas are provided at multiple locations on the insulation material, the sum of their areas shall be considered the area of ​​the exposed portion.

[0055] The thickness of the thermal insulation material is not particularly limited, but is preferably between 3 and 550 mm. The thickness of the insulating material is the shortest distance between the side of the insulating material facing the heat source and the side opposite to the heat source.

[0056] The external shape of the insulating material is cylindrical, with an internal space for housing the heat-generating element.

[0057] The cross-sectional shape of the space formed inside the insulating member in a direction perpendicular to the longitudinal direction is not particularly limited and may be circular, such as a perfect circle or an ellipse, or it may be a polygon such as a square, pentagon, or hexagon.

[0058] The bulk density of the thermal insulation material is not particularly limited, but is generally between 0.05 and 0.4 g / cm³. 3 It is preferable that this be the case. The bulk density of an insulating material can be measured by dividing its weight by its volume, which is determined from its external dimensions.

[0059] The insulating material does not need to be molded into a cylindrical shape from the beginning. In other words, the thermal insulation member may be an assembly of multiple thermal insulation members, each having a cylindrical shape divided into multiple sections. The heat insulating member may also be a sheet-like molded body made of carbon fibers with a roughly rectangular shape in plan view, which has been deformed so that a columnar space for housing a heat-generating element is formed inside.

[0060] When a sheet-like molded body is deformed into a cylindrical shape, the parts where the ends of the sheet-like molded body come into contact (contact parts) may be in contact in a manner that allows them to be separated from each other, or they may be joined together with a carbon-based adhesive or the like, or they may be stitched together with carbon fibers or the like.

[0061] The thermal insulation material of the present invention may further include a cylindrical molded body made of carbon fiber that covers the outer surface of the thermal insulation member. The above-mentioned molded body is made of carbon fiber and has a roughly columnar space inside that can accommodate an insulating material. The thermal insulation performance of the present invention can be further enhanced if the thermal insulation material has a cylindrical molded body (hereinafter also simply referred to as the molded body) made of carbon fibers that covers the outer surface of the thermal insulation member.

[0062] The molded body is preferably cylindrical in shape, slightly larger than the heat insulating member. The thickness of the molded body is preferably 3 to 50 mm.

[0063] The molded body can preferably be made of the same carbon fiber base material that constitutes the heat insulating member. Furthermore, the type of carbon fibers, average fiber length, and average fiber diameter constituting the molded body may be the same as, or different from, those of the carbon fiber base material.

[0064] The bulk density of the molded body is not particularly limited, but is generally between 0.05 and 0.4 g / cm³. 3 It is preferable that this be the case.

[0065] The surface of the molded body may have a base layer or a pyrolysis carbon layer formed on it, similar to an insulating material.

[0066] It is preferable that the heat insulating material and the molded body are in contact with each other in a manner that allows them to be separated. When the insulation material and the molded body are in contact in a way that allows them to be separated from each other, only the insulation material can be replaced if it deteriorates or wears out. This reduces the time required to replace the insulation material and also reduces the amount of insulation material that needs to be replaced. Consequently, the cost of replacing the insulation material can be reduced.

[0067] An example of the thermal insulation material of the present invention will be described below with reference to the drawings. Figure 1 is a schematic perspective view showing an example of the thermal insulation material of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1.

[0068] As shown in Figure 1, the thermal insulation material 1 includes a thermal insulation member 10. The heat insulating member 10 has a cylindrical space 30 on its inside for housing a heat-generating element. Furthermore, the heat insulating member 10 has a substantially cylindrical shape that extends in the longitudinal direction (Z direction in Figure 1). When viewed from the Z direction, the top view shape of the heat insulating member 10 is annular, relative to the planes parallel to the X and Y directions which are perpendicular to the longitudinal direction (Z direction).

[0069] Since space 30 is a space for housing a heat-generating element (not shown), the insulation material 1 is an insulation material that surrounds the heat-generating element.

[0070] As shown in Figure 2, the heat insulating member 10 has a surface (first main surface 10a) that is positioned on the side of the space 30 that houses the heat-generating element, a surface (second main surface 10b) that is positioned on the opposite side from the surface on the side of the heat-generating element, and end surfaces 10c that are located at both ends in the longitudinal direction and connect the first main surface 10a and the second main surface 10b.

[0071] Figure 3 is a magnified view of the area enclosed by the dashed line in Figure 2. However, in Figure 3, components other than the thermal insulation material are omitted. As shown in Figure 3, the heat insulating member 10 has a base material 13 made of carbon fibers and a pyrolysis carbon layer 11. The thermal insulation member 10 may have an underlayer 12 between the base material 13 and the pyrolysis carbon layer 11. The thickness of the heat insulating member 10 is the shortest distance between the first main surface 10a and the second main surface 10b, as shown by the double arrow d in Figure 3. 10 This is the length indicated by [the symbol].

[0072] The pyrolysis carbon layer 11 is a layer containing pyrolysis carbon. As shown in Figure 3, pyrolysis carbon layers 11a, 11b, and 11c containing pyrolysis carbon are formed on the first main surface 10a, the second main surface 10b, and the end surface 10c of the heat insulating member 10, respectively.

[0073] The base layer 12 is a layer containing carbon-based particles between carbon fibers. As shown in Figure 3, a base layer 12 may be provided between the pyrolysis carbon layer 11 and the substrate 13. The base layer may include a base layer 12a provided on the first main surface 10a side of the insulating member 10, a base layer 12b provided on the second main surface 10b side, and a base layer 12c provided on the end surface 10c side.

[0074] When insulation material 1 is used, the heat-generating element is placed in the space 30 shown in Figures 1 and 2. This will be explained using Figure 4.

[0075] Figure 4 is a schematic, partially cutaway perspective cross-sectional view showing an example of a heating device constructed using the thermal insulation material of the present invention. The heating device 100 shown in Figure 4 comprises an insulating material 1, a crucible 50, and an induction heating coil 70 for heating the crucible 50. The crucible 50 is heated by the induced current generated by the induction heating coil 70. Therefore, the crucible 50 is a heating element. The crucible 50 has a cavity 51. Therefore, the heating device 100 can heat the substance placed in the cavity 51 by heating the crucible 50 with the induction heating coil 70.

[0076] The crucible 50, which is the heating element, is surrounded by an insulating material 1. The space in which the heat-generating crucible 50 is located is part or all of the space 30 contained within the insulation material 1. An induction heating coil 70 is wrapped around the outer surface of the insulation material 1.

[0077] In the heating device 100, the crucible 50, which is the heating element, and the insulating material 1 are in direct contact, but a gap may be provided between the crucible 50, which is the heating element, and the insulating material 1 as appropriate.

[0078] In the heating device 100 shown in Figure 4, the material constituting the crucible 50 is not particularly limited as long as it is a conductor, but graphite is preferred because it has excellent heat resistance and durability at high temperatures (especially 2000°C or higher).

[0079] The heating element is not limited to those used for heating solids and liquids as described above. For example, the heating element may have a cylindrical shape made of graphite and heat the gas passing through it. Furthermore, the heating element may be a heater that is directly heated by electricity, and there may be a gap between the heating element and the insulation material into which the object to be heated can fit.

[0080] Figure 5 is a magnified view of a portion of the area shown by the dashed line in Figure 4. As shown in Figure 5, a pyrolysis carbon layer 11 is formed on the first main surface 10a of the heat insulating member 10, so that it reflects the radiant light emitted from the heat-generating element 50 to prevent radiative heat transfer and also has excellent gas barrier properties.

[0081] Furthermore, as shown in Figure 5, there are exposed areas 111 on the surface of the heat insulating member 10 where the pyrolysis carbon layer 11 is not formed.

[0082] The surface of the heat insulating member 10 consists of a first main surface 10a (the area indicated by A1 in Figure 5) located on the side facing the heat-generating element, a second main surface 10b (the area indicated by A2 in Figure 5) located on the side opposite to the heat-generating element, and an end surface 10c (the area indicated by A3 in Figure 5). Furthermore, the first main surface 10a (region A1) located on the heating element side is a region where the distance from the end face 10c is up to 20% of the length of the heat insulating member 10 (in Figure 5, A 11 The region shown by (A in Figure 5) and the other region (A in Figure 5)12 the region indicated by) is divided. Similarly, the second main surface 10b (region A2) arranged on the opposite side from the heating element is a region where the distance from the end face 10c is up to 20% of the length of the heat insulating member 10 (in FIG. 5, A 21 the region indicated by) and other regions (in FIG. 5, A 22 the region indicated by) is divided.

[0083] The exposed portion 111 is located in region A3, region A 11 and exists only in at least one location selected from the group consisting of region A2. In other words, in the heat insulating material of the present invention, region A 12 has no exposed portion 111 formed therein.

[0084] For example, in the heat insulating member 10 constituting the heat insulating material 1 shown in FIG. 5, region A which is a part of region A2 21 the exposed portion 111 exists at two locations only in.

[0085] Since the exposed portion 111 exists only in the above-mentioned regions of the heat insulating member 10, it is possible to prevent the pyrolytic carbon layer from being destroyed by degassing of the heat insulating material while maintaining the gas barrier property.

[0086] In the heat insulating material 1 shown in FIG. 5, among the surfaces of the heat insulating member 10, region A 21 has the exposed portion 111 formed therein, and the exposed portion 111 is located in region A 12 may exist in regions other than.

[0087] Although the heating element 50 and the heat insulating member 10 are in close contact with each other in FIG. 5, a gap may be provided by appropriately adjusting the space between the heating element 50 and the heat insulating member 10. The gap is also a part of the space 30 left by accommodating the heating element 50 having a smaller dimension than the space 30 in the space 30 shown in FIG. 2.

[0088] Examples of heat insulating materials in which exposed portions are provided at different positions are shown in FIG. 6, FIG. 7 and FIG. 8.

[0089] Figure 6 is a schematic cross-sectional view showing another example of the thermal insulation material of the present invention. In the thermal insulation material 2 shown in Figure 6, the exposed portion 111 is located in region A of the surface of the thermal insulation member 10. 11 It is located in the area indicated by [the symbol].

[0090] Figure 7 is a schematic cross-sectional view showing yet another example of the thermal insulation material of the present invention. In the thermal insulation material 3 shown in Figure 7, the exposed portion 111 is provided in the region indicated by region A3 on the surface of the thermal insulation member 10.

[0091] Figure 8 is a schematic cross-sectional view showing yet another example of the thermal insulation material of the present invention. In the thermal insulation material 4 shown in Figure 8, the exposed portion 111 is located in region A of the surface of the thermal insulation member 10. 22 It is located in the area indicated by [the symbol].

[0092] [Method of manufacturing insulation material] The thermal insulation material of the present invention can be manufactured by a method for manufacturing the thermal insulation components that constitute the thermal insulation material of the present invention. The case in which the thermal insulation material of the present invention further comprises a cylindrical molded body made of carbon fibers covering the outer surface of the thermal insulation member will be described later.

[0093] The thermal insulation member constituting the thermal insulation material of the present invention can be manufactured by a method comprising, for example, a molded body preparation step of preparing a molded body of carbon fibers; a base layer formation step of impregnating the surface of the molded body of carbon fibers with a slurry containing carbon-based particles to form a base layer; and a thermal decomposition carbon layer formation step of forming a thermal decomposition carbon layer containing thermal decomposition carbon while masking a part of the surface of the molded body on which the base layer has been formed.

[0094] (Molded object preparation process) In the molded body preparation process, a molded body made of carbon fiber is prepared.

[0095] Methods for obtaining molded carbon fiber products include the needling method and the papermaking method.

[0096] In the needling method, for example, carbon fibers with an average fiber length of 10 mm to 10,000 mm are laminated in a sheet form, and a molded body made of carbon fibers can be obtained by entangling the inorganic fibers together through needling.

[0097] In the papermaking method, for example, a suspension is prepared by dispersing carbon fibers with an average fiber length of 2 mm to 8 mm in a dispersion medium such as water, and a molded body made of carbon fibers can be obtained by papermaking using a mold.

[0098] The mold used for papermaking can be flat, or it can be a curved mold of the desired shape. In other words, the molded body obtained in the molded body preparation process may be cylindrical from the beginning, but at this point it may not be cylindrical, but for example, it may be roughly rectangular in plan view. If the molded body has a roughly rectangular shape in plan view, it is deformed into a cylindrical shape by the deformation process described later.

[0099] In the papermaking method, the suspension may contain an organic binder. When an organic binder is included in the suspension, the carbon fibers are fixed together during papermaking, improving moldability. Furthermore, since the organic binder remains on the molded body made of carbon fibers and can restrain the carbon fibers, the handling of the molded body can be improved in a stage prior to the underlayer formation process described later.

[0100] Furthermore, the organic binder that may be included in the suspension is preferably the same as the organic binder that may be used in the base layer formation process described later.

[0101] As the carbon fibers used in the molded body preparation process, carbon fibers that constitute the heat insulating material can be suitably used. A molded carbon fiber body serves as the base material for the heat insulating component.

[0102] (Underlying layer formation process) In the base layer formation process, a slurry containing carbon-based particles is impregnated onto the surface of a molded carbon fiber body, and the base layer is formed by firing.

[0103] While the firing conditions are not particularly limited, it is preferable to fire at a temperature of 700 to 2100°C in a non-oxidizing atmosphere for 1 to 12 hours. Non-oxidizing atmospheres include inert and reducing atmospheres.

[0104] An inert atmosphere is an atmosphere whose main component is an inert gas. Examples of inert gases include nitrogen and argon.

[0105] A reducing atmosphere is an atmosphere whose main component is a reducing gas. Examples of reducing gases include hydrogen, carbon monoxide, hydrocarbons, and chlorine.

[0106] As the carbon-based particles used in the sub-layer formation process, carbon-based particles capable of constituting an insulating material can be suitably used.

[0107] In the sub-layer formation process, it is preferable to expose carbon fibers on the surface. One method for exposing carbon fibers on the surface is to slightly reduce the amount of slurry impregnated into the molded body during the base layer formation process compared to the amount that would normally be impregnated into the molded body. This results in areas on the surface of the molded body that are not impregnated with slurry, exposing the carbon fibers.

[0108] The slurry used in the subsoil formation process may contain an organic binder. When an organic binder is included in the slurry, carbon-based particles tend to remain near the surface of the molded body when it is immersed in the slurry, thus preventing the underlying layer from becoming too thick.

[0109] As the organic binder, both organic binders that carbonize when heated in a non-oxidizing atmosphere and organic binders that decompose when heated in a non-oxidizing atmosphere and do not leave any residue can be used. Furthermore, the organic binder may be soluble in the solvent, or it may be dispersed in the solvent as fine particles.

[0110] If the organic binder is one that carbonizes when heated in a non-oxidizing atmosphere, the carbonized organic binder functions as a carbon-based adhesive, enabling a strong bond between carbon-based particles and carbon fibers. Furthermore, it prevents carbon-based particles constituting the underlying layer, which are unevenly distributed on the surface of the molded product, from detaching from the carbon fibers.

[0111] Examples of organic binders that can be carbonized include phenolic resins, polyvinyl alcohol (PVA), and pitch.

[0112] If the slurry does not contain an organic binder, it is preferable to immerse the molded body in the slurry and then impregnate the surface of the molded body with an organic binder solution. This allows the organic binder to function as a carbon-based adhesive, similar to when the slurry contains an organic binder, enabling a strong bond between the carbon particles and carbon fibers.

[0113] In the base layer formation process, the molded body is first immersed in a slurry containing carbon-based particles and a solvent, but without an organic binder. Subsequently, the molded body is immersed in an organic binder solution. This reduces the penetration of the organic binder into the interior of the molded body, thereby suppressing a decrease in thermal insulation performance.

[0114] (Pyrolysis carbon layer formation process) In the pyrolysis carbon layer formation process, a pyrolysis carbon layer containing pyrolysis carbon is formed while a portion of the surface of the molded body with the base layer is masked. Since the thermal decomposition carbon layer does not form in the masked areas, these areas become exposed.

[0115] The method for forming a pyrolysis carbon layer on top of the underlying layer is not particularly limited, but one example is a method of forming a pyrolysis carbon layer by chemical vapor deposition using a CVD furnace. The process of forming a pyrolysis carbon layer using a CVD furnace is also called the CVD process.

[0116] The conditions for the CVD process are not particularly limited. The raw material gas can be a hydrocarbon gas, such as methane, ethane, propane, or ethylene.

[0117] The temperature for the CVD process is preferably, for example, 800 to 2000°C. When the temperature of the CVD process is above 800°C, the raw material gas decomposes easily, making it easier to form a pyrolysis carbon layer. If the temperature of the CVD process is below 2000°C, the sublimation of carbon fibers can be suppressed and deterioration can be prevented.

[0118] If the carbon fibers constituting the molded body are carbonaceous, the temperature of the CVD process should preferably be 1700°C or lower. Carbonaceous carbon fibers transform into graphite when exposed to high temperatures, and their thermal conductivity decreases. This can lead to alterations such as an increase in properties. Therefore, by performing the CVD process at a temperature of 1700°C or lower, the alteration of carbon fibers to graphite can be suppressed, and the thermal insulation properties of the molded product can be maintained.

[0119] One method for masking the surface of a molded body with a base layer is to bring a ceramic block into contact with the surface of the molded body. In this method, the pyrolysis carbon layer is not formed on the part of the molded body's surface that was in contact with the ceramic block, and this part remains exposed.

[0120] Therefore, when the heat-generating element is positioned to cover the element, the heat-generating member can be manufactured by performing the above CVD process while masking is applied to at least one location on the surface facing the heat-generating element (corresponding to the first main surface) up to 20% of the length of the heat-generating member from the end face, the surface opposite the heat-generating element (corresponding to the second main surface), and the end face. The thermal insulation material obtained here is a thermal insulation material that constitutes the thermal insulation material of the present invention, and is also the thermal insulation material of the present invention itself.

[0121] (Deformation process) Furthermore, the external shape of the molded body prepared in the molded body preparation process does not necessarily have to be cylindrical from the beginning. For example, in the molded body preparation process, a molded body with a roughly rectangular shape in plan view (a sheet-like molded body) may be produced, and this may be deformed into a cylindrical shape by a deformation process. Furthermore, when performing the sub-layer formation process and / or the pyrolysis carbon layer formation process, it is preferable that the deformation process be performed before the sub-layer formation process and the pyrolysis carbon layer formation process.

[0122] The sheet-like molded body may have, for example, a substantially rectangular shape in plan view, having a first end face and a second end face facing each other in the longitudinal direction, a first main face and a second main face facing each other in the thickness direction perpendicular to the longitudinal direction, and a first side face and a second side face facing each other in the width direction perpendicular to the length direction and the thickness direction. Here, of the first and second main surfaces, the main surface on the heating element side is the pyrolysis carbon layer.

[0123] The distance between the first and second end faces in a sheet-like molded body is the length of the sheet-like molded body and corresponds to the length of the inner circumference of the heat insulating member.

[0124] The distance between the first main surface and the second main surface in a sheet-like molded body is the thickness of the sheet-like molded body, and corresponds to the thickness of the heat insulating material.

[0125] The distance between the first and second sides of the sheet-like molded body is the width of the sheet-like molded body and corresponds to the height of the heat insulating member.

[0126] When a sheet-like molded body is deformed to form a heat insulating member, the first and second end faces of the sheet-like molded body may be in contact with each other in a separable manner, or they may be bonded together with a carbon-based adhesive or the like, or they may be sewn together with thread or the like. The thread may be one that burns away during firing, or it may not burn away during firing.

[0127] If the thermal insulation material of the present invention further comprises a cylindrical molded body made of carbon fibers that covers the outer surface of the thermal insulation member, in addition to the above-described method for manufacturing the thermal insulation material of the present invention, it can be manufactured by a step of preparing a cylindrical molded body made of carbon fibers that covers the outer surface of the thermal insulation member, and a step of covering the outer surface of the thermal insulation member with the obtained molded body.

[0128] The process of preparing a cylindrical molded body made of carbon fiber can be carried out using the same process as the molded body preparation process described above, by molding the carbon fiber into a predetermined shape.

[0129] The thermal insulation material of the present invention can be suitably used, for example, in heating devices such as heating furnaces. In the thermal insulation material of the present invention, when the base material is a carbon fiber papermaking body, it can be particularly suitable for use in induction heating furnaces. Furthermore, the thermal insulation material of the present invention can be suitably used, for example, as a thermal insulation material for keeping the crucible warm (insulating) in a single crystal growth apparatus for Si or SiC.

[0130] This specification discloses the following:

[0131] (1) The present disclosure relates to a thermal insulation material having a thermal insulation member comprising a substrate containing carbon fibers and a thermal decomposition carbon layer formed on the surface of the substrate containing thermal decomposition carbon, The aforementioned heat insulating member has a cylindrical shape with an internal space for housing a heating element. The heat insulating member has a first main surface which is the outer peripheral surface on the side facing the heating element, a second main surface which is the outer peripheral surface on the side opposite to the heating element, and an end surface which connects the first main surface and the second main surface. The thermal insulation material is characterized in that at least one location selected from the group consisting of the end face of the thermal insulation member, the region of the first main surface of the thermal insulation member whose length from the end face is up to 20% of the thermal insulation member, and the second main surface of the thermal insulation member, is an exposed portion on the surface of the base material in which the pyrolysis carbon layer is not formed.

[0132] Disclosure (2) is the thermal insulation material according to Disclosure (1), wherein the exposed portion is located on the end face and / or the second main face of the thermal insulation member.

[0133] Disclosure (3) is the thermal insulation material according to Disclosure (1) or (2), wherein the exposed portion is located in a region of the second main surface of the thermal insulation material whose length from the end face is up to 20% of the length of the thermal insulation material.

[0134] Disclosure (4) is an insulating material in any combination of any of Disclosures (1) to (3), characterized in that the ratio of the area of ​​the exposed portion to the total surface area of ​​the insulating material is 1% to 4.9%.

[0135] Disclosure (5) is an insulating material in any combination of the pyrolysis carbon layer with any of Disclosures (1) to (4), wherein the pyrolysis carbon layer has a thickness of 2 μm to 60 μm.

[0136] Disclosure (6) is an insulating material in any combination of any of Disclosures (1) to (5), wherein the base material is the carbon fiber needle mat or the carbon fiber papermaking body.

[0137] Disclosure (7) is an insulating material in any combination of any of Disclosures (1) to (6), wherein the average fiber length of the carbon fibers is 2 mm to 8 mm.

[0138] Disclosure (8) is an insulating material in any combination of any of Disclosures (1) to (7), further comprising a base layer containing carbon-based particles between carbon fibers between the base material and the pyrolysis carbon layer.

[0139] The present disclosure (9) is the thermal insulation material according to the present disclosure (8), wherein the carbon fibers are exposed on the surface of the substrate layer.

[0140] Disclosure (10) is an insulating material according to Disclosure (8) or (9), wherein the carbon-based particles and carbon fibers of the substrate layer are joined to each other with a carbon-based adhesive.

[0141] Disclosure (11) is an insulating material in any combination with any of Disclosures (8) to (10), wherein the carbon-based particles are at least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fiber particles.

[0142] Disclosure (12) is a thermal insulation material in any combination of carbon-based particles with any of Disclosures (8) to (11), wherein the carbon-based particles have an average particle diameter of 10 nm to 500 μm.

[0143] Disclosure (13) states that the substrate layer is an insulating material having a thickness of 10 μm to 1000 μm, in any combination with any of Disclosures (8) to (12).

[0144] The present disclosure (14) is an insulating material in any combination with any of the present disclosures (1) to (13), further comprising a cylindrical molded body made of carbon fiber that covers the outer surface of the insulating member.

[0145] This disclosure (15) is an insulating material according to this disclosure (14), wherein the insulating member and the molded body are in contact with each other in a separable manner.

[0146] (Examples) The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0147] (Example 1) [Manufacturing of thermal insulation materials] [Molded object preparation process] Carbon fibers (average fiber diameter: 13 μm, average fiber length: 3.3 mm) were formed by papermaking to obtain a cylindrical molded body made of carbon fibers (cylindrical shape with inner diameter 95 mm, height 190 mm, and thickness 10 mm). This molded body was heated to 2000°C in an inert atmosphere to carbonize the organic binder (phenolic resin) contained in the molded body.

[0148] [Underlying layer formation process] After processing the surface of a cylindrical molded body to shape it, a slurry containing an organic binder and carbon-based particles was applied to the entire surface of the cylindrical molded body. For the carbon-based particles, graphite particles with an average particle size of 10 μm were used. A phenolic resin was used as the organic binder.

[0149] Next, a cylindrical molded body coated with slurry was placed in a furnace with a reducing atmosphere and heated at 2000°C for 1 hour. This created a base layer on the surface of the carbon fiber substrate in which carbon-based particles were arranged between carbon fibers, and the carbon-based particles and carbon fibers were bonded to each other with a carbon-based adhesive.

[0150] At this point, observation of the substrate surface with a polarizing microscope confirmed that some carbon fibers were exposed on the surface. Furthermore, it was confirmed that the carbon-based particles and carbon fibers were bonded together by a carbon-based adhesive, which was carbonized by heating the organic binder in the slurry under a reducing atmosphere.

[0151] [CVD process] Next, the cylindrical molded body with the base layer formed was placed in a CVD furnace. After the furnace was evacuated to lower the air pressure, the raw material gas was introduced to form a pyrolysis carbon layer on the surface of the base layer. A cylindrical molded body was placed on support pins, and a pyrolysis carbon layer was formed while the body was point-supported by the support pins.

[0152] In the above CVD process, since a base layer is formed on the surface of the cylindrical molded body, the raw material gas does not penetrate into the interior of the molded body during this process, but instead settles on the surface. At this time, the carbon fibers exposed on the surface act as anchors, firmly connecting the molded body made of carbon fibers with the pyrolysis carbon layer.

[0153] The area in contact with the support pin is the masked area, and is an exposed area where the pyrolysis carbon layer will not form. The support pins are conical ceramic blocks with a 10mm diameter tip (top surface), positioned 30mm from the widthwise end of the cylindrical molded body and spaced 36mm apart along the circumference. There were a total of 10 ceramic blocks. Furthermore, the bulk density of the insulating material was measured to be 0.18 g / cm³.

[0154] The thermal insulation material had a total of 10 circular exposed sections, each 10 mm in diameter, spaced 30 mm apart along the circumference of the sheet-like molded body, at a position 16% of the length of the thermal insulation material from one end of the main surface (second main surface) opposite the heating element. The total surface area of ​​the insulation material is 131,947 mm². 2 The total exposed area is 785 mm². 2 That was the case. Therefore, the ratio of the exposed area to the total surface area of ​​the thermal insulation material was 0.6%.

[0155] When the insulating material was cut along its thickness and the area near the surface of the cut surface was observed with a polarizing microscope, it was confirmed that a 20 μm thick pyrolysis carbon layer was formed on the surface of the insulating material, and furthermore, a 100 μm thick underlayer was formed directly beneath the pyrolysis carbon layer.

[0156] (Comparative Example 1) A thermal insulation material according to Comparative Example 1 was obtained using the same procedure as in Example 1, except that the CVD process was carried out without masking. The thermal insulation material in Comparative Example 1 has no exposed parts.

[0157] (Comparative Example 2) The only difference in the CVD process was that the ceramic blocks were positioned inside the cylindrical molded body at a distance of 95 mm from the end face, at 30 mm intervals. Otherwise, the thermal insulation material according to Comparative Example 2 was obtained using the same procedure as in Example 1. In the thermal insulation member constituting the thermal insulation material according to Comparative Example 2, 10 circular exposed portions with a diameter of 10 mm were provided at 30 mm intervals in the area of ​​the first main surface facing the heat-generating element, extending 50% from the end face of the thermal insulation member. The ratio of the exposed area to the total surface area of ​​the thermal insulation material was the same as in Example 1.

[0158] [Consumable Test] SiC powder was placed in a graphite crucible (cylindrical shape with an outer diameter of 95 mm, an inner diameter of 85 mm, and a height of 190 mm), and with the lid closed, it was inserted into the space inside the insulating material constituting the insulating material according to Example 1 and Comparative Example 1, and heated at 2350°C for 12 hours by high-frequency induction heating in an inert atmosphere. After heating was complete, the crucible was removed from the inside of the insulating material, and the surface of the insulating material on the crucible side was visually inspected to check the degree of deterioration of the insulating material and whether there was any damage to the pyrolysis carbon layer.

[0159] In the thermal insulation material of Example 1, there was almost no deterioration of the thermal insulation component, and no damage occurred to the pyrolysis carbon layer.

[0160] On the other hand, damage was observed in the pyrolysis carbon layer of the thermal insulation material according to Example 1. In the insulation material related to Comparative Example 1, wear tests revealed damage to the pyrolysis carbon layer, and it was confirmed that deterioration of the insulation material was progressing, mainly around the damaged area.

[0161] Furthermore, in the case of the insulation material related to Comparative Example 2, it was confirmed that deterioration of the insulation material was progressing, mainly in the exposed areas.

[0162] Based on the above results, it was confirmed that the thermal insulation material of the present invention can prevent the destruction of the thermally decomposed carbon layer due to degassing of the thermal insulation material while maintaining gas barrier properties, and thus exhibits excellent durability. [Explanation of Symbols]

[0163] 1, 2, 3, 4 Insulation 10. Insulation material 10a The heat-generating side of the insulating material (first main surface) 10b The side of the insulating material opposite to the side facing the heat-generating element (second main surface) 10c End face of the insulating member 11. Pyrolysis carbon layer 11a Pyrolytic carbon layer provided on the first main surface of the thermal insulation member 11b Pyrolytic carbon layer provided on the second main surface of the insulating material 11c A pyrolysis carbon layer provided on the end face of the insulating member. 12 Base layer 12a Substrate layer provided on the first main surface side of the thermal insulation member 12b Substrate layer provided on the second main surface side of the insulating material 12c Substrate layer provided on the end face side of the insulating member 13 Base material 30 Space for housing the heating element 50 Heating element (crucible) 51 Cavity 70 Induction heating coil 100 Heating device 111 Exposed part

Claims

1. A thermal insulation material comprising a base material containing carbon fibers and a thermal decomposition carbon layer formed on the surface of the base material, wherein the thermal insulation member comprises The aforementioned heat insulating member has a cylindrical shape with an internal space for housing a heating element. The heat insulating member has a first main surface which is the outer peripheral surface on the side facing the heating element, a second main surface which is the outer peripheral surface on the side opposite to the heating element, and an end surface which connects the first main surface and the second main surface. At least one location selected from the group consisting of the end face of the insulating member, the region of the first main surface of the insulating member whose length from the end face is up to 20% of the insulating member, and the second main surface of the insulating member, there is an exposed portion on the surface of the substrate where the pyrolysis carbon layer is not formed. An insulating material characterized in that the ratio of the area of ​​the exposed portion to the total surface area of ​​the insulating member is 1% to 4.9%.

2. A thermal insulation material comprising a base material containing carbon fibers and a thermal decomposition carbon layer formed on the surface of the base material, the thermal insulation material comprising a thermal insulation member, The aforementioned heat insulating member has a cylindrical shape with an internal space for housing a heating element. The heat insulating member has a first main surface which is the outer peripheral surface on the side facing the heating element, a second main surface which is the outer peripheral surface on the side opposite to the heating element, and an end surface which connects the first main surface and the second main surface. At least one location selected from the group consisting of the end face of the insulating member, the region of the first main surface of the insulating member whose length from the end face is up to 20% of the insulating member, and the second main surface of the insulating member, there is an exposed portion on the surface of the substrate where the pyrolysis carbon layer is not formed. The thermal insulation material is characterized by further comprising a cylindrical molded body made of carbon fiber that covers the outer surface of the thermal insulation member.

3. The thermal insulation material according to claim 2, wherein the thermal insulation member and the molded body are in contact with each other in a separable manner.

4. The thermal insulation material according to any one of claims 1 to 3, wherein the exposed portion is located on the end face and / or the second main surface of the thermal insulation member.

5. The thermal insulation material according to any one of claims 1 to 3, wherein the exposed portion is located in a region of the second main surface whose length from the end face is up to 20% of the length of the thermal insulation material.

6. The thermal insulation material according to any one of claims 1 to 3, wherein the thermal decomposition carbon layer has a thickness of 2 μm to 60 μm.

7. The thermal insulation material according to any one of claims 1 to 3, wherein the base material is the carbon fiber needle mat or the carbon fiber papermaking body.

8. The thermal insulation material according to any one of claims 1 to 3, wherein the average fiber length of the carbon fibers is 2 mm to 8 mm.

9. The thermal insulation material according to any one of claims 1 to 3, further comprising a base layer containing carbon-based particles between carbon fibers between the base material and the pyrolysis carbon layer.

10. The thermal insulation material according to claim 9, wherein the carbon fibers are exposed on the surface of the underlying layer.

11. The thermal insulation material according to claim 9, wherein the carbon-based particles and carbon fibers of the underlying layer are joined to each other with a carbon-based adhesive.

12. The thermal insulation material according to claim 9, wherein the carbon-based particles are at least one carbon-based particle selected from the group consisting of graphite, carbon black, glassy carbon particles, and crushed carbon fiber particles.

13. The thermal insulation material according to claim 9, wherein the carbon-based particles have an average particle diameter of 10 nm to 500 μm.

14. The thermal insulation material according to claim 9, wherein the aforementioned base layer has a thickness of 10 μm to 1000 μm.

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