Insulation

Abstract

We provide insulation materials with excellent thermal insulation properties. [Solution] A thermal insulation material characterized by comprising a cylindrical thermal insulation member containing carbon fibers and a laminate of thermal insulation sheets, which are arranged along the inside of the thermal insulation member and consist of laminated thermal insulation sheets containing carbon fibers.

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 semiconductor manufacturing furnaces and ceramic sintering furnaces, due to their high heat resistance and excellent insulation performance.

[0003] The shape of the insulation material is determined appropriately depending on the shape of the object to be insulated. For example, to insulate a columnar object, a cylindrical insulation material is used.

[0004] Patent Document 1 describes a furnace with a bulk density of 1.0 to 2.2 g / cm³ for the innermost layer. 3 A superheated furnace surrounded by graphite plates is disclosed. Patent Document 1 discloses a furnace with a bulk density of 1.0 to 2.2 g / cm³ for the innermost layer. 3 By surrounding the system with graphite plates, the carbon vapor pressure within the system is reduced to 10 -8 It has been disclosed that even at temperatures of 2000°C or higher, especially those exceeding 2800°C, which are above atm, the temperature distribution in the innermost layer of the furnace can be reduced, and as a result, damage to the innermost surface of the insulation material and a decrease in insulation performance due to ultra-high temperatures can be suppressed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2000-186891 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the method described in Patent Document 1, a hard graphite plate is used as the innermost layer, which makes it easy for gaps to form between the insulating material placed outside the graphite plate and the graphite plate. This can cause a large temperature distribution inside the furnace and worsen the insulation performance. In addition, because graphite plates have a high bulk density and high thermal conductivity, there were problems such as large heat dissipation from the furnace at high temperatures and the hassle of replacing worn graphite plates (innermost layer).

[0007] This invention was made to solve the above-mentioned problems, and aims to provide an insulating material with excellent thermal insulation properties. [Means for solving the problem]

[0008] The present invention is characterized by comprising a cylindrical insulating member containing carbon fibers and an insulating sheet laminate formed by laminating insulating sheets containing carbon fibers, which are arranged along the inside of the insulating member.

[0009] In the thermal insulation material of the present invention, a laminate of thermal insulation sheets containing carbon fibers is arranged along the inside of a cylindrical thermal insulation member containing carbon fibers. Since both the thermal insulation member containing carbon fibers and the laminate of thermal insulation sheets are fiber molded bodies mainly composed of carbon fibers, the laminate of thermal insulation sheets arranged inside the thermal insulation member easily conforms to the shape of the thermal insulation member and is positioned along the inside of the thermal insulation member. As a result, gaps are less likely to form between the thermal insulation member and the laminate of thermal insulation sheets, and the temperature distribution inside the furnace can be reduced. In addition, since both the thermal insulation member and the laminate of thermal insulation sheets have a lower bulk density than graphite, which is a hard material, heat dissipation from the furnace at high temperatures can be reduced. This makes it possible to reduce the power input required to heat the furnace.

[0010] In the thermal insulation material of the present invention, the thickness of the thermal insulation sheet is preferably 0.3 to 2.0 mm. When the thickness of the insulation sheet is within the above range, the carbon fibers contained in the insulation sheet tend to orient in the direction of the sheet's surface, thus enhancing the insulation effect when it is placed along the inside of the insulation material.

[0011] In the thermal insulation material of the present invention, the density of the thermal insulation sheet is 0.15 to 0.28 g / cm³. 3 It is preferable that this be the case. When the density of the insulation sheet is within the above range, the thermal conductivity at high temperatures is low, which further enhances the insulation performance and is therefore particularly preferable.

[0012] In the thermal insulation material of the present invention, it is preferable that the thermal insulation sheet laminate is formed by winding and laminating 2 to 30 layers of the thermal insulation sheet. When the thermal insulation sheet laminate is constructed by winding and laminating 2 to 30 layers of thermal insulation sheets, it is possible to prevent gaps from forming between the thermal insulation material and the thermal insulation sheet laminate, while also making it easier for the thermal insulation sheet laminate to reflect heat released at high temperatures, thereby improving thermal insulation performance.

[0013] In the thermal insulation material of the present invention, it is preferable that the thermal insulation sheet contains flaky graphite. Because flake graphite easily reflects heat emitted from a heating element, the presence of flake graphite in an insulating sheet can improve its thermal insulation performance.

[0014] In the thermal insulation material of the present invention, the thermal insulation member is preferably an integrally molded body. When the insulation material is a single molded piece, it is less likely that there will be areas with low insulation performance within the insulation material. Therefore, it can exhibit high insulation performance.

[0015] In the thermal insulation material of the present invention, it is preferable that the thermal insulation member and the thermal insulation sheet laminate are arranged in a manner that allows them to be separated. If the insulation material and the laminated insulation sheet are arranged in a separable manner, then when the insulation material deteriorates, only the inner laminated insulation sheet can be replaced, making it easy to replace the innermost layer.

[0016] In the thermal insulation material of the present invention, the density of the thermal insulation member is 0.05 to 0.25 g / cm³. 3 It is preferable that this be the case. When the density of the heat insulation member is within the above range, it is particularly suitable because sufficient heat insulation performance can be maintained at low temperatures.

[0017] In the heat insulation material of the present invention, the density of the heat insulation sheet is preferably 0.03 g / cm 3 or more higher than the density of the heat insulation member. When the density of the heat insulation sheet is 0.03 g / cm 3 or more higher than the density of the heat insulation member, the heat insulation sheet with a relatively high density makes it easier to reflect the heat released at high temperatures, and the heat insulation member with a relatively low density can reduce the heat conductivity at low temperatures. Therefore, the heat insulation performance can be made higher.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a perspective view schematically showing an example of the heat insulation material of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of the heat insulation material shown in FIG. 1 when viewed from above. [Figure 3] FIG. 3 is a perspective view schematically showing an example of the heat insulation sheet constituting the heat insulation material of the present invention. [Figure 4] FIG. 4 is a cross-sectional view schematically showing an example of the heat insulation sheet. [Figure 5] FIG. 5 is an enlarged cross-sectional view schematically showing another example of the heat insulation sheet.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments, and can be appropriately changed and applied within the range that does not change the gist of the present invention.

[0020] [Heat Insulation Material] The heat insulation material of the present invention is characterized by comprising a cylindrical heat insulation member containing carbon fiber and a heat insulation sheet laminate containing carbon fiber arranged along the inner side of the heat insulation member.

[0021] Figure 1 is a schematic perspective view showing an example of the thermal insulation material of the present invention. As shown in Figure 1, the thermal insulation material 1 consists of a cylindrical thermal insulation member 50 and a laminated thermal insulation sheet 10 placed inside it. The insulation material 1 is cylindrical with an outer diameter R1, an inner diameter R2, and a height h, and has a cylindrical space 100 inside.

[0022] The thickness t0 of the insulation material 1 is the length of the shortest distance connecting the inner surface 1a and the outer surface 1b of the insulation material 1 in a plane perpendicular to the height direction (indicated by arrow Z in Figure 1) (a plane parallel to arrows X and Y in Figure 1). This length is measured at eight points at 45-degree intervals along the central angle of the inscribed circle of the inner surface 1a of the insulation material 1, and the average value is used.

[0023] The shape of the insulation material can be cylindrical or rectangular, but cylindrical is preferred.

[0024] The cross-sectional area of ​​the space inside the insulation material, when cut in a direction parallel to a plane perpendicular to the height direction, is 20 to 8000 cm². 2 It is preferable that this be the case.

[0025] When the insulation material is cylindrical, the inner diameter of the insulation material is preferably 50 to 1000 mm. The inner diameter R2 of the insulation material 1 is the diameter of the inscribed circle of the inner surface 1a of the insulation material 1 in a plane perpendicular to the height direction, and is the average of the diameters of the inscribed circles of both end faces of the insulation material 1 and the cross-sections obtained by bisecting the height direction.

[0026] When the insulation material is cylindrical, the outer diameter is preferably between 60 and 1200 mm. The outer diameter R1 of the insulation material 1 is the diameter of the inscribed circle of the outer surface 1b of the insulation material 1 in a plane perpendicular to the height direction, and is the average of the diameters of the inscribed circles of both end faces of the insulation material 1 and the cross-sections obtained by bisecting the insulation material 1 in the height direction.

[0027] The height of the insulation material is preferably between 150 and 1000 mm. The height is measured at eight points on the inner surface 1a of insulation material 1, at 45-degree intervals between the central angles of the inscribed circle, and the average value is used.

[0028] Figure 2 is a magnified view of a top-down view of the insulation material shown in Figure 1. As shown in Figure 2, in the insulation material 1, the insulation sheet laminate 10 is arranged along the inner surface 50a of the insulation member 50. There is no gap between the inner surface 50a of the insulation member 50 and the insulation sheet laminate 10. Gaps are less likely to form between the insulating material and the laminated insulating sheet, which reduces the temperature distribution inside the furnace. In addition, since both the insulating material and the insulating sheet have a lower bulk density than the hard material graphite, heat dissipation from the furnace at high temperatures can be reduced.

[0029] The inner surface 1a of the insulation material 1 is the surface exposed to the cylindrical space 100, and the outer surface 1b of the insulation material 1 is the surface exposed on the opposite side from the cylindrical space 100. The inner surface 1a and outer surface 1b of the insulation material 1 face each other in a plane perpendicular to the height direction Z of the insulation material 1. The inner surface 1a of the insulation material 1 is also the innermost surface 10a of the insulation sheet laminate 10. The outer surface 1b of the insulation material 1 is also the outer surface 50b of the insulation member 50.

[0030] The insulation material 1 consists of two layers of insulation sheets 11 wound and laminated along the inner surface 50a of the insulation member 50. In other words, the insulation sheet laminate 10 is made up of laminated insulation sheets 11. Although not shown in Figure 2, the insulation sheet 11 is a single long sheet with no seams or joints.

[0031] The insulating sheet 11 that constitutes the innermost surface 10a of the insulating sheet laminate 10 is exposed to a cylindrical space 100 provided inside the insulating material 1. Therefore, it can be said that the insulating sheet 11 that constitutes the innermost surface 10a of the insulating sheet laminate 10 constitutes the inner surface 1a of the insulating material 1. The thermal insulation sheet 11 that constitutes the outermost surface 10b of the thermal insulation sheet laminate 10 is arranged along the inner surface 50a of the thermal insulation member 50.

[0032] As shown in Fig. 2, the thickness t0 of the heat insulating material 1 is the sum of the thickness t1 of the heat insulating sheet laminate 10 and the thickness t2 of the heat insulating member 50. The thickness t1 of the heat insulating sheet laminate 10 is the product of the thickness t 11 of the heat insulating sheet 11 and the number of layers of the heat insulating sheet 11 (two layers in Fig. 2). The thickness t1 of the heat insulating sheet laminate and the thickness t 11 of the heat insulating sheet are measured at eight positions every 45 degrees of the central angle of the inscribed circle of the inner surface 1a of the heat insulating material 1, and the average value is taken.

[0033] In addition, in Figs. 1 and 2, the heat insulating sheet laminate 10 is arranged so as to cover all of the inside 50a of the heat insulating member 50. However, as long as the heat insulating sheet laminate 10 is arranged along the inside 50a of the heat insulating member 50, it may cover only a part of the inside 50a of the heat insulating member 50.

[0034] The heat insulating member 50 and the heat insulating sheet laminate 10 are preferably arranged in a separable state. When the heat insulating member 50 and the heat insulating sheet laminate 10 are arranged in a separable state, when the heat insulating material 1 deteriorates, only the inner heat insulating sheet laminate 10 can be replaced, so that the replacement becomes easy.

[0035] The thickness t 11 of the heat insulating sheet is preferably 0.3 to 2.0 mm. When the thickness of the heat insulating sheet is 0.3 to 2.0 mm, the number of layers of the heat insulating sheet arranged inside the heat insulating member can be increased, and the variation in density in the in-plane direction of the heat insulating sheet is less likely to be reflected in the variation in density in the circumferential direction. As a result, the variation in density in the circumferential direction is reduced, and it is possible to suppress an increase in the temperature distribution in the furnace due to a partial decrease in heat insulating performance and partial deterioration of the heat insulating material.

[0036] The thickness t0 of the heat insulating material is preferably 5 to 100 mm. When the thickness of the heat insulating material is within the above range, it is possible to prevent the heating furnace from becoming large while having sufficient heat insulating performance.

[0037] Figure 3 is a schematic perspective view showing an example of an insulating sheet that constitutes the insulating material of the present invention. Since the heat insulating sheet 11 is a flexible sheet, it may be stored in a rolled-up state, for example, as shown in Figure 3.

[0038] (Insulation sheet) The insulation sheet contains carbon fiber.

[0039] The average fiber length of the carbon fibers is preferably between 0.4 mm and 10,000 mm. Furthermore, the average fiber length of the carbon fibers may be 0.4 mm to 4 mm, or 10 mm to 10,000 mm. The average fiber length of carbon fibers is calculated by measuring the longitudinal length of 20 randomly selected carbon fibers using any method and averaging the results.

[0040] The average fiber diameter of the carbon fibers is preferably 1 μm to 30 μm. If the average fiber diameter of the carbon fibers is 30 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. The average fiber diameter of carbon fibers is calculated by measuring the fiber diameter of 20 randomly selected carbon fibers using a scanning electron microscope (SEM) and averaging the results.

[0041] Carbon fibers can be pitch-based, PAN-based, or rayon-based, and either graphite-based or carbonaceous carbon fibers can be used.

[0042] The heat insulating sheet is preferably made of 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 oriented carbon fibers, they can exhibit high thermal insulation properties and are particularly suitable as thermal insulation sheets for thermal insulation materials.

[0043] When the insulation sheet is made of a carbon fiber needle mat, the average fiber length of the carbon fibers is preferably between 10 mm and 10,000 mm. When the heat insulating sheet is made of carbon fiber paper, the average fiber length of the carbon fibers is preferably 0.4 mm to 4 mm.

[0044] The heat insulating sheet preferably contains flaky graphite. Because flake graphite easily reflects heat emitted from a heating element, the presence of flake graphite in an insulating sheet can improve its thermal insulation performance.

[0045] Scaly graphite is graphite that has a thin, scaly appearance. Specifically, flaky graphite with a thickness of 100 μm or less is defined as flaky graphite.

[0046] Flake graphite reflects heat more easily than other carbon-based materials. Therefore, including flake graphite in an insulating sheet can improve its thermal insulation performance.

[0047] Figure 4 is a schematic cross-sectional view showing an example of an insulating sheet. The thermal insulation sheet 11 shown in Figure 4 contains flake graphite 20. However, the carbon fibers that make up the thermal insulation sheet 11 are omitted in Figure 4.

[0048] Because flake graphite easily reflects heat emitted from a heating element, the presence of flake graphite in an insulating sheet can improve its thermal insulation performance.

[0049] Natural graphite can be used as the flaky graphite.

[0050] The average particle size of the flake graphite is preferably 25 to 400 μm. The average particle size of flake graphite can be measured by sieve analysis in accordance with the "Industrial Analysis and Testing Methods for Natural Graphite" described in JIS M 8511 (2014).

[0051] The arrangement (orientation) of flake-like graphite in the thermal insulation sheet is not particularly limited, but it is preferable that it be oriented along the in-plane direction of the thermal insulation sheet. The in-plane direction of the thermal insulation sheet is the direction perpendicular to the thickness direction of the thermal insulation sheet. In the heat insulating sheet 11 shown in Figure 4, the flake-like graphite 20 is oriented along a plane perpendicular to the thickness direction of the heat insulating sheet 11 (the direction indicated by the double-headed arrow t). When the flake-like graphite is oriented in the direction of the plane, it becomes easier to reflect the heat emitted from the heating element, thereby improving the thermal insulation performance.

[0052] The content of flake graphite is not particularly limited, but it is preferably 5-30% of the weight of the heat insulating sheet.

[0053] In a thermal insulation sheet, it is preferable that the carbon fibers and flake graphite are joined via a carbonaceous binder. In this case, it can be said that the thermal insulation sheet contains a carbonaceous binder in addition to the carbon fibers and flake graphite.

[0054] Figure 5 is a schematic, enlarged cross-sectional view showing another example of an insulating sheet. In the heat insulating sheet 11 shown in Figure 5, the flake-like graphite 20 is oriented in a direction perpendicular to the thickness direction of the heat insulating sheet 11 (indicated by the double-headed arrow t in Figure 5). In addition, in the heat insulating sheet 11, the carbon fibers 30 and the flake-shaped graphite 20 are bonded together via the carbonaceous binder 40 contained in the heat insulating sheet 11. This prevents the flake-shaped graphite 20 from falling off. The carbonaceous binder 40 is formed when the organic binder is carbonized by heating in a non-oxidizing atmosphere.

[0055] The density of the insulation sheet is 0.15-0.28 g / cm³. 3 It is preferable that this be the case. The density of the insulation sheet is determined by dividing the insulation material into eight sections in a plane perpendicular to the height direction of the insulation material, with a central angle of 45 degrees at the center of the inscribed circle of the inner surface 1a of the insulation material. One layer of insulation sheet is separated from the eight sections of insulation material, and the density is calculated from the volume and weight obtained from the external shape (plan view shape and thickness) of each section. The average value of these values ​​is taken as the density of the insulation sheet.

[0056] It is preferable that the insulation sheet is wound and laminated in 2 to 30 layers on the inside of the insulation material. When the number of windings and layers of the insulation sheet is within the above range, variations in the circumferential density of the insulation material can be particularly suppressed. The insulation sheet may be a sheet-shaped insulation sheet placed inside the insulation member, or a pre-wound laminate of insulation sheets may be placed inside the insulation member. The thermal insulation sheet or laminate of thermal insulation sheets and the thermal insulation member may be fitted together, fixed with carbon fixing members such as threads or pins, or joined together via an organic binder or the like.

[0057] The ratio of the volume of the laminated insulation sheet to the volume of the total insulation material is preferably 3 to 50%.

[0058] (Insulation material) The insulating material contains carbon fiber. As the carbon fibers constituting the heat insulating material, those similar to the carbon fibers constituting the heat insulating sheet can be suitably used.

[0059] The heat insulating material is preferably made of a three-dimensionally formed carbon fiber body. Because the carbon fibers in a three-dimensional carbon fiber molded body are oriented perpendicular to the thickness direction of the insulating material, it can exhibit high thermal insulation properties and is particularly suitable as a molded body for constituting an insulating material.

[0060] The average fiber length of the carbon fibers is preferably 0.4 mm to 4 mm. The average fiber length of carbon fibers is calculated by measuring the longitudinal length of 20 randomly selected carbon fibers using any method and averaging the results.

[0061] The thickness of the thermal insulation material is not particularly limited, but is preferably 3 to 100 mm. The thickness of the insulating material is the shortest distance between the heat-generating side of the insulating material and the side opposite to the heat-generating side. The thickness t2 of the insulating material 50 is measured at eight locations where the central angle of the inscribed circle of the inner surface 1a of the insulating material 1 differs by 45 degrees, and the average value is used.

[0062] When the thermal insulation material is composed of a three-dimensional molded body of carbon fibers, it is preferable that the carbon fibers are joined together via a carbonaceous binder. In this case, it can be said that the thermal insulation material contains a carbonaceous binder in addition to the carbon fibers.

[0063] In thermal insulation materials, carbon fibers are joined together via a carbonaceous binder contained within the material. This prevents the carbon fibers from falling out. Carbonaceous binders are formed when organic binders are carbonized by heating in a non-oxidizing atmosphere.

[0064] 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.

[0065] The heat insulating material is preferably a so-called integrally molded body that is formed into a cylindrical shape from the beginning. When the insulation material is a single molded piece, it is less likely that there will be areas with low insulation performance within the insulation material. Therefore, it can exhibit high insulation performance.

[0066] The density of the insulating material is 0.05 to 0.25 g / cm³. 3 It is preferable that this be the case. The density of the insulating material is particularly preferable when it is within the above range, as it can maintain sufficient insulating performance even at low temperatures. The density of the thermal insulation material is determined by dividing the thermal insulation material into eight sections in a plane perpendicular to the height direction of the thermal insulation material, with a central angle of 45 degrees at the center of the inscribed circle of the inner surface 1a of the thermal insulation material. These eight sections are then separated, and a rectangular parallelepiped containing at least 35% of the volume of each section is cut out. The density is then calculated from the volume and weight obtained from the external shape (plan view shape and thickness) of each section, and the average value is used. If it is not possible to cut out a rectangular parallelepiped containing at least 35% of the volume of each section, the volume of the eight sections of thermal insulation material can also be measured using a known three-dimensional measuring machine.

[0067] The density of the insulation sheet is 0.03 g / cm³ lower than the density of the insulation material. 3 A higher value is preferable. The density of the insulation sheet is 0.03 g / cm³ lower than the density of the insulation material. 3 If the density is higher than the above, the relatively high-density insulating sheet will more easily reflect the heat released at high temperatures, and the relatively low-density insulating material will reduce the thermal conductivity at low temperatures, thereby improving the insulation performance.

[0068] [Method of manufacturing insulation material] The thermal insulation material of the present invention can be manufactured, for example, by the first to third methods described below.

[0069] [Method 1] One first method for manufacturing the thermal insulation material of the present invention is to attach a thermal insulation sheet along the inside of a thermal insulation member. [Manufacturing of insulation sheets] A thermal insulation sheet can be manufactured, for example, by a method comprising a thermal insulation sheet precursor preparation step of preparing a carbon fiber thermal insulation sheet precursor, and a firing step of firing the thermal insulation sheet precursor.

[0070] (Preparation process for the thermal insulation sheet precursor) In the preparation process for the thermal insulation sheet precursor, a thermal insulation sheet precursor made of carbon fibers is prepared.

[0071] A thermal insulation sheet precursor can be obtained, for example, by preparing a suspension in which carbon fibers are dispersed in a dispersion medium such as water and forming it into a sheet (papermaking), or by performing a needle punching treatment on an aggregate of carbon fibers.

[0072] The suspension may contain an organic binder. The presence of an organic binder in the suspension improves moldability by fixing the carbon fibers together during papermaking. The organic binder then carbonizes during subsequent heat treatment (in a non-oxidizing atmosphere) to become a carbonaceous binder, thus continuing to bind the carbon fibers together even after heat treatment.

[0073] Examples of organic binders that act as carbonaceous binders include phenolic resins, polyvinyl alcohol (PVA), and pitch.

[0074] If the papermaking method does not include an organic binder in the suspension, or if the carbon fiber aggregate is subjected to needle punching, the organic binder may be incorporated into the resulting insulating sheet precursor by applying a slurry containing an organic binder to the insulating sheet precursor.

[0075] The thickness of the heat insulating sheet precursor is preferably 0.3 to 3.0 mm. If the thickness of the thermal insulation sheet precursor is within the above range, a thermal insulation sheet with a thickness of 0.3 to 2.0 mm can be obtained.

[0076] (Firing process) An insulating sheet can be obtained by firing an insulating sheet precursor in a non-oxidizing atmosphere at 1500-2400°C.

[0077] Non-oxidizing atmospheres include inert and reducing atmospheres.

[0078] An inert atmosphere is an atmosphere whose main component is an inert gas. Examples of inert gases include nitrogen and argon.

[0079] A reducing atmosphere is an atmosphere whose main component is a reducing gas. Examples of reducing gases include hydrogen, carbon monoxide, hydrocarbons, and chlorine.

[0080] [Manufacturing of thermal insulation materials] The thermal insulation member constituting the thermal insulation material of the present invention can be manufactured, for example, by a method comprising a thermal insulation member precursor preparation step of preparing a thermal insulation member precursor made of carbon fibers, and a firing step of firing the thermal insulation member precursor.

[0081] (Preparation process for thermal insulation material precursor) In the preparation process for the thermal insulation material precursor, a thermal insulation material precursor made of carbon fibers is prepared.

[0082] One method for obtaining a precursor for a heat insulating material made of carbon fibers is the three-dimensional papermaking method.

[0083] In the three-dimensional papermaking method, for example, a suspension is prepared by dispersing carbon fibers with an average fiber length of 0.4 mm to 4 mm in a dispersion medium such as water, and a curved mold with numerous holes on the side of a hollow cylinder is immersed in the suspension. Then, by pumping the water inside the curved mold, carbon fibers are deposited on the surface of the curved mold, and a cylindrical heat insulating material precursor made of carbon fibers can be obtained.

[0084] In the case of three-dimensional papermaking, the suspension may contain an organic binder. When an organic binder is included in the suspension, the carbon fibers are fixed together during three-dimensional papermaking, improving moldability.

[0085] (Firing process) The thermal insulation material can be obtained by firing a thermal insulation material precursor in a non-oxidizing atmosphere at 1500 to 2400°C. The firing conditions are preferably the same as those used in the firing process for firing the heat insulating sheet precursor.

[0086] The external shape of the resulting heat insulating member may be adjusted by machining.

[0087] [Assembly process] By attaching two or more layers of insulation sheets manufactured according to the above procedure along the inside of the insulation member manufactured according to the above procedure, the insulation material of the present invention can be manufactured in which an insulation sheet laminate is arranged along the inside of the insulation member.

[0088] The laminated insulation sheet may cover only a portion of the inside of the insulation member, or it may cover the entire inside of the insulation member, as long as it is aligned with the inside of the insulation member.

[0089] The number of layers in the winding of the insulation sheet is preferably 2 to 30.

[0090] The surfaces in contact between the heat insulating sheet and the heat insulating material may be fixed with carbon fixing members such as threads or pins, joined via an organic binder, or joined by impregnating the heat insulating sheet with an organic binder. Examples of organic binders include phenolic resin, polyvinyl alcohol (PVA), and pitch.

[0091] The external shape of the resulting insulation material may be adjusted by machining.

[0092] [Second method] A second method for producing the thermal insulation material of the present invention involves stacking two or more thermal insulation sheet precursors described in the first method along the inside of the thermal insulation member precursor described in the first method, and firing them at 1500 to 2400°C in a non-oxidizing atmosphere. The firing conditions are preferably the same as those used in the firing process for firing the heat insulating sheet precursor.

[0093] The contact surfaces of the heat insulating sheet precursor and the heat insulating member precursor may be fixed with a carbon fixing member such as a thread or pin, joined via an organic binder, or joined by impregnating the heat insulating sheet precursor with an organic binder. Examples of organic binders include phenolic resin, polyvinyl alcohol (PVA), and pitch.

[0094] The external shape of the resulting insulation material may be adjusted by machining.

[0095] [Third Method] A third method for manufacturing the thermal insulation material of the present invention is to obtain a thermal insulation sheet laminate by firing a laminate of thermal insulation sheet precursors obtained by winding and laminating the thermal insulation sheet precursors described in the first method, and then fitting this laminate inside the thermal insulation member described in the first method. (Manufacturing of thermal insulation sheet laminates) The thermal insulation sheet laminate can be obtained by winding and laminating the thermal insulation sheet precursor described in the first method, and then firing it at 1500 to 2400°C in a non-oxidizing atmosphere. The firing conditions are preferably the same as those used in the firing process for firing the heat insulating sheet precursor.

[0096] The thermal insulation sheet precursor may be laminated by winding it around a core material, for example.

[0097] The number of winding layers of the heat-insulating sheet precursor is preferably 2 to 30 layers.

[0098] The layers of thermal insulation sheet precursors may be joined via an organic binder applied to the surface of the thermal insulation sheet precursors, or they may be joined by impregnating the thermal insulation sheet precursors with an organic binder. Examples of organic binders include phenolic resin, polyvinyl alcohol (PVA), and pitch. The amount of organic binder can be 5-25% of the weight of the insulating sheet precursor.

[0099] The external shape of the resulting thermal insulation sheet laminate may be adjusted by machining.

[0100] This specification discloses the following:

[0101] This disclosure (1) includes a tubular heat insulating member containing carbon fiber, The thermal insulation material is characterized by comprising a laminate of thermal insulation sheets, which are arranged along the inside of the aforementioned thermal insulation member, and which are laminates of thermal insulation sheets containing carbon fibers.

[0102] Disclosure (2) is the thermal insulation material described in Disclosure (1), wherein the thickness of the thermal insulation sheet is 0.3 to 2.0 mm.

[0103] (3) of this disclosure states that the density of the heat insulating sheet is 0.15 to 0.28 g / cm³. 3 The thermal insulation material is as described in (1) or (2) of this disclosure.

[0104] Disclosure (4) is an insulating material in which the insulating sheet laminate is formed by winding and laminating 2 to 30 layers of the insulating sheet, in any combination with any of Disclosures (1) to (3).

[0105] Disclosure (5) states that the thermal insulation sheet is a thermal insulation material comprising flake graphite in any combination of any of Disclosures (1) to (4).

[0106] Disclosure (6) is an insulating material which is an integrally molded body and is an insulating material which is any combination of any of Disclosures (1) to (5).

[0107] Disclosure (7) is an insulating material in any combination of any of Disclosures (1) to (6), wherein the insulating member and the insulating sheet laminate are arranged in a separable manner.

[0108] This disclosure (8) states that the density of the thermal insulation material is 0.05 to 0.25 g / cm³. 3 The thermal insulation material is any combination of any of (1) to (7) of the present disclosure.

[0109] This disclosure (9) states that the density of the heat insulating sheet is 0.03 g / cm³ higher than the density of the heat insulating member. 3 The above is an insulating material in any combination of any of (1) to (8) of the present disclosure.

[0110] (Examples) The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0111] (Manufacturing Example 1) (Manufacturing of thermal insulation materials) A suspension containing carbon fibers (average fiber diameter: 13 μm, average fiber length: 0.7 mm) and an organic binder (phenol resin) in a ratio of 100:15 (by weight, organic binder is calculated on a solid content basis) was prepared. An integral mold for manufacturing a cylindrical molded body was immersed in the suspension, and the liquid inside the mold was sucked out with a vacuum pump, causing the solid components of the suspension to be deposited in a cylindrical shape on the surface of the integral molded body. After removing the cylindrical deposit from the mold and drying it, it was heated to 2000°C under an inert atmosphere to carbonize the organic binder (phenol resin) contained in the molded body, thereby obtaining a cylindrical heat insulating member. The obtained cylindrical heat insulating member was processed to have an outer diameter of 130 mm, an inner diameter of 113 mm, a height of 210 mm, and a thickness of 8.5 mm.

[0112] (Manufacturing example 2) (Manufacturing of thermal insulation sheet laminates) Next, a suspension containing carbon fibers (average fiber diameter: 13 μm, average fiber length: 0.7 mm), flaky graphite (average particle size: 100 μm), and an organic binder (phenol resin) in a ratio of 100:17:25 (by weight, organic binder is calculated on a solid content basis) was molded by a continuous papermaking method to obtain a thermal insulation sheet precursor (sheet thickness 1.0 mm) made of carbon fibers.

[0113] Next, the obtained thermal insulation sheet precursor was wound around a core material with a diameter of 80 mm to create a cylindrical laminate of thermal insulation sheet precursors. The number of windings and layers was 32. At this time, the thermal insulation sheet precursor was impregnated with an organic binder (phenol resin) at a rate of 25 parts by weight per 100 parts by weight of the thermal insulation sheet precursor before lamination. By heating to 2000°C under an inert atmosphere, the organic binder (phenol resin) contained in the thermal insulation sheet precursor was carbonized, and the thermal insulation sheet laminate according to Example 1 (sheet thickness 0.9 mm) was obtained in which carbon fibers and flake graphite were joined by a carbonaceous binder. After this, it was machined to a cylindrical shape with an outer diameter of 113 mm, an inner diameter of 96 mm, a height of 210 mm, and a thickness of 8.5 mm.

[0114] (Example 1) (Manufacturing of insulation materials) Next, a laminate of insulating sheets was placed along the inside of the insulating member to obtain the insulating material according to Example 1.

[0115] (Comparative Example 1) A thermal insulation material with an outer diameter of 130 mm, an inner diameter of 96 mm, a height of 210 mm, and a thickness of 17 mm was obtained for Comparative Example 1 using the same method as in Example 1, except that a laminate of thermal insulation sheets was not placed inside the thermal insulation member. The thermal insulation material for Comparative Example 1 consists only of the thermal insulation member manufactured in Manufacturing Example 1, and no laminate of thermal insulation sheets is placed inside the thermal insulation member.

[0116] (Comparative Example 2) The simulation was performed under the condition that a graphite sheet molded body with an outer diameter of 113 mm, an inner diameter of 96 mm, a height of 210 mm, and a thickness of 8.5 mm was placed inside the insulating material, without placing an insulating sheet laminate inside the insulating material.

[0117] (Measurement of thermal conductivity) The thermal conductivity in the thickness direction of the thermal insulation sheet laminate and thermal insulation member according to Example 1 and Comparative Example 1 was measured by the laser flash method. The thermal conductivity of the laminated insulation sheet was 0.058 W / m·K at 200°C, 0.216 W / m·K at 1000°C, 0.597 W / m·K at 1800°C, and 0.742 W / m·K at 2000°C. The thermal conductivity of the insulation material was 0.190 W / m·K at 200°C, 0.360 W / m·K at 1000°C, and 0.850 W / m·K at 1800°C.

[0118] (Comparative test simulation) The thermal insulation properties (power input) of the thermal insulation materials in Example 1, Comparative Example 1, and Comparative Example 2 were simulated using the following method. The thermal conductivity of the thermal insulation sheet laminate, graphite sheet molded body, and thermal insulation member related to Example 1, Comparative Example 1, and Comparative Example 2 was input. The thermal conductivity of the graphite sheet molded body was calculated using values ​​of 71.5 W / m·K at 500°C, 55.7 W / m·K at 1000°C, 44.4 W / m·K at 1800°C, and 43.8 W / m·K at 2000°C. As a fixed condition, the specific heat capacity of all components was set in 50°C increments so that it was 922.2 J / kg·K at 100°C, 1580.2 J / kg·K at 500°C, 1934.6 J / kg·K at 1000°C, 2066.4 J / kg·K at 1500°C, and 2135.0 J / kg·K at 2000°C. The power input to the induction heating furnace was simulated with an emissivity of 0.72. A cylindrical graphite crucible with an outer diameter of 96 mm and a height of 156 mm was placed inside the insulation material of Example 1, Comparative Example 1, and Comparative Example 2. The crucible was heated to 2080°C, simulating a furnace under vacuum. The total power consumption of the coil, the heat generated by the insulation material, and the heat generated by the crucible was calculated as the input power. The results are shown in Table 1. Furthermore, the 3D steady-state calculation software STAR-CCM was used for the simulation.

[0119] [Table 1]

[0120] As shown in Table 1, it was confirmed that the thermal insulation material according to Example 1, in which a laminate of thermal insulation sheets was arranged along the inside of the thermal insulation member, required less power input to heat the furnace than the thermal insulation material according to Comparative Example 1, in which a laminate of thermal insulation sheets was not arranged inside the thermal insulation member. From this, it can be said that the thermal insulation material of the present invention has excellent thermal insulation performance.

[0121] Furthermore, since the thermal insulation sheet laminate constituting the thermal insulation material in Example 1 has a lower thermal conductivity compared to a graphite plate of the same volume, it is considered that the power input for heating the furnace can be reduced and that it has superior thermal insulation performance compared to Comparative Example 2, in which a graphite sheet molded body was used instead of the thermal insulation sheet laminate. [Explanation of Symbols]

[0122] 1. Insulation 1a Inner surface of the insulation material 1b Outer surface of the insulation material 10. Thermal insulation sheet laminate 10a Innermost layer of the insulation sheet laminate 10b Outermost surface of the thermal insulation sheet laminate 11. Insulation sheet 20. Scaly graphite 30 carbon fiber 40 Carbonaceous binders 50 Insulation material 50a Inside of the insulation material 50b Outer surface of the insulation material 100 cylindrical space R1 insulation material outer diameter Inner diameter of R2 insulation material t0 Thickness of insulation material t1 Thickness of the laminated insulation sheet t 11 Thickness of the insulation sheet Thickness of t2 insulation material h Height of insulation

Claims

1. A cylindrical insulating member containing carbon fiber, An insulating material characterized by comprising an insulating sheet laminate formed by laminating insulating sheets containing carbon fibers, which are arranged along the inside of the insulating member.

2. The insulating material according to claim 1, wherein the thickness of the insulating sheet is 0.3 to 2.0 mm.

3. The density of the aforementioned heat insulating sheet is 0.15 to 0.28 g / cm³. ３ The thermal insulation material according to claim 1 or 2.

4. The thermal insulation material according to claim 1 or 2, wherein the thermal insulation sheet laminate is formed by winding and laminating 2 to 30 layers of the thermal insulation sheet.

5. The thermal insulation material according to claim 1 or 2, wherein the thermal insulation sheet contains flaky graphite.

6. The thermal insulation material according to claim 1 or 2, wherein the thermal insulation member is an integrally molded body.

7. The thermal insulation material according to claim 1 or 2, wherein the thermal insulation member and the thermal insulation sheet laminate are arranged in a separable manner.

8. The density of the aforementioned heat insulating material is 0.05 to 0.25 g / cm³. ３ The thermal insulation material according to claim 1 or 2.

9. The density of the aforementioned heat insulating sheet is 0.03 g / cm³ lower than the density of the aforementioned heat insulating material. ３ The thermal insulation material according to claim 1 or 2, which is higher than or equal to the above.

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