Composite heat insulating sheet having flexibility

Abstract

To provide a composite heat insulating sheet capable of being simply constructed on a construction surface composed of a curved surface.SOLUTION: A two-layer composite heat insulating sheet has a flexible two-layer structure in which a sheet-like ceramic fiber heat insulating material 1 preferably made of one or more materials of mullite fiber, alumina fiber, alkaline earth silicate fiber, and alumina-silica fiber is combined with a sheet-like microporous heat insulating material 2 which has inorganic fine particles mixed with organic fibers as a main material. Preferably, the sheet-like microporous heat insulating material has a thermal conductivity of 0.10 W / (m K) or less at 600°C, and when a 5 mm thick piece is measured for bending strength with a span of 100 mm, a deflection amount during breaking is 3.0 mm or more and 10.0 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flexible composite insulating sheet, and in particular to a composite insulating sheet with excellent insulating properties that can be easily applied to surfaces that have curved surfaces, such as molten metal containers such as ladles, cylindrical heat treatment furnaces, and pipes. [Background technology]

[0002] In various industrial fields such as metal smelting, petrochemicals, and ceramics, raw materials and intermediate products are heated, and cylindrical heat treatment furnaces and other equipment, as well as cylindrical exhaust ducts and chimneys, are widely used. Molten metal is transported using bottomed cylindrical ladles and other molten metal containers, and high-temperature fluids are continuously transported using piping. In order to reduce energy consumption as much as possible by suppressing heat loss due to radiation, etc., insulation materials are installed on the inner and outer surfaces of these facilities, equipment, and piping. The inner and outer surfaces of these facilities, equipment, and piping, such as heat treatment furnaces, are often curved, and in this case, insulation materials suitable for installation on curved surfaces are required.

[0003] In order to accommodate the above-mentioned curved construction surfaces, a heat insulating material that can be freely bent along the curved surface has been proposed. For example, Non-Patent Documents 1 and 2 disclose a technique for producing heat insulating materials in various forms, such as a futon-like, quilt-like, or segmented form, by covering a microporous heat insulating material made of nano-sized silica particles with a fiber covering material and sewing it. However, in these forms of heat insulating materials, the microporous heat insulating material itself does not exist in the sewn part, or the thickness is thinner than other parts, so there is a risk of insufficient heat insulating properties.

[0004] On the other hand, a coated insulation material is known in which a thinned microporous insulation material is coated with an aluminum-coated glass cloth sheet or the like. However, this coated insulation material cannot be used when the curvature of the application surface is small because the coating material restricts the bending of the insulation material along the curved surface. In addition, since microporous insulation materials are generally physically fragile, the microporous insulation material in the coating material may be damaged during processing such as cutting and drilling for application or during transportation. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Catalog "High-performance Insulation Material Microtherm", Japan Microtherm Co., Ltd., February 2004, page 5 [Non-Patent Document 2] Catalog "Porextherm WDS", Kurosaki Harima Corporation, October 1, 2005, page 5 Summary of the Invention [Problem to be solved by the invention]

[0006] However, insulation materials applied to areas exposed to high-temperature atmospheres are required to have high heat resistance as well as high heat insulation properties. As a result of extensive research by the inventors to meet these requirements, they have discovered that since ceramic fiber insulation materials have slightly lower thermal conductivity than microporous insulation materials but have excellent heat resistance, it is effective to use a two-layer structure in which ceramic fiber insulation materials are used on the hot side and microporous insulation materials on the cold side.

[0007] However, when making a two-layered insulation material, the microporous insulation material must first be fixed to the surface to be installed, such as the steel shell, and then the ceramic fiber insulation material must be attached to that surface, which is a concern as it will take time and effort to install. As a result of further investigation, we thought that it would be possible to improve the ease of installation by combining and integrating these two types of insulation material in advance. In this case, in order to make a composite insulation material that can be installed on curved surfaces, the microporous insulation material will be attached to the curved surface of the ceramic fiber insulation material on the cold side opposite the installation surface. However, since microporous insulation material, which is made by compressing inorganic fine particles into a plate shape, generally has poor flexibility, there was a risk of the microporous insulation material being damaged when it was bent.

[0008] As a countermeasure against the above, it is conceivable to process the molded body of the microporous insulating material into a plurality of rectangular pieces with a trapezoidal cross section and arrange them at a fine pitch on the curved surface of the ceramic fiber insulating material, but this countermeasure is rather time-consuming and there is a risk that the insulation properties will be insufficient in the gaps between the adjacent rectangular pieces. The present invention has been made in consideration of the above circumstances, and aims to provide a composite insulating sheet having a flexible two-layer structure in which a microporous insulating material and a ceramic fiber insulating material are integrated, which can be easily applied to an application surface that is composed of a curved surface. [Means for solving the problem]

[0009] In order to achieve the above-mentioned objective, the flexible composite insulating sheet of the present invention is characterized by having a flexible two-layer structure that combines a sheet-shaped ceramic fiber insulating material and a sheet-shaped microporous insulating material in which organic fibers are mixed with inorganic fine particles as the main material. Effect of the Invention

[0010] According to the present invention, construction can be easily performed even when construction is performed on a construction surface that is constituted by a curved surface. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view of a composite insulating sheet according to an embodiment of the present invention used as a lining insulating material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the composite heat insulating sheet according to the present invention will be described. The composite heat insulating sheet according to the embodiment of the present invention is suitable for heat insulating a curved surface such as the main body of an electrical device that requires heat insulation or a pipe through which a high-temperature fluid flows, and has a flexible two-layer composite heat insulating sheet configuration in which a sheet-shaped ceramic fiber heat insulating material and a sheet-shaped microporous heat insulating material in which organic fibers are mixed with inorganic fine particles as a main material are combined.

[0013] More specifically, the sheet-like microporous insulating material, which is one of the components of an embodiment of the composite insulating sheet of the present invention, has the form of a sheet-like insulating material in which inorganic microparticles made of a metal oxide as the main material are mixed with organic fibers, and this sheet-like insulating material may further contain infrared scattering material, fire-resistant fibers, and porous insulating aggregate as necessary.

[0014] The sheet-shaped microporous insulation material is produced by mixing the inorganic fine particles, organic fiber, and other raw materials in a predetermined ratio, loading the resulting mixture into a mold, compressing and molding it, and then heating it to about 150°C to compress and mold it again. In this way, the sheet-shaped insulation material is produced through heat compression molding, so it has a structure in which the organic fiber is thermally fused to the inorganic fine particles. This allows the deflection amount at break to be 3.0 mm or more when the bending strength of a 5 mm thick material is measured with a span of 100 mm, and a maximum deflection amount of 10.0 mm can be achieved.

[0015] Thus, the sheet-shaped microporous insulation material, which is one of the components of the composite insulation material according to the embodiment of the present invention, has flexibility, so that it can be easily curved without breaking even when applied to a curved surface with a radius of curvature of about 125 mm. The above-mentioned amount of deflection can be changed by appropriately adjusting the material and form of the organic fiber to be mixed in the microporous insulation material, the mixing ratio, the heating temperature during heat compression molding, the holding time, and other molding conditions. The above-mentioned microporous insulation material has a heat resistance of 1400°C. The heat resistance temperature may be referred to as the maximum use temperature. In this specification, the heat resistance temperature T°C refers to a case where the heat linear shrinkage rate is 4% or less when heated at an ambient temperature T°C for 24 hours.

[0016] The inorganic fine particles are made of a metal oxide having a heat resistance of about 1000 to 1200°C. The metal oxide is preferably one or more selected from the group consisting of silica, alumina, magnesia, mullite, and zirconia. The inorganic fine particles are preferably made of inorganic fine particles having an average particle size of 0.5 μm or less. This can reduce the void size in the molded body, and when refractory fibers or infrared scattering materials are contained, the void size between the particles of the inorganic fine particles can be further reduced by these refractory fibers or infrared scattering materials, so that the convection heat transfer of gas at high temperatures can be suppressed. In this specification, the average particle size is the median diameter (D50) at which the cumulative distribution curve based on volume measured by a laser diffraction type particle size distribution measuring device is 50%.

[0017] The organic fibers are preferably those that melt at 150°C or less, and the material is not particularly limited, but examples thereof include polyester, polyvinyl alcohol, polyethylene, polypropylene, or a composite of two or more of them. In the case of a composite, a core-sheath fiber of polyethylene (PE) / polypropylene (PP) is preferable. The core-sheath fiber is more preferable in that the core part remains even after melting, and excellent bending performance can be maintained. The core-sheath fiber is a fiber having a double structure of a core part made of polypropylene and a sheath part made of polyethylene that surrounds the core part in a substantially concentric axial shape. The size of the fiber is preferably such that the fiber thickness scale T (dtex) obtained by substituting the measured length L (m) and weight W (g) into T = (10000 x W) / L is in the range of 1.0 to 20, and the fiber length measured by an electron microscope is preferably in the range of 3 to 20 mm.

[0018] The infrared scattering material is not particularly limited as long as it has a heat resistance of 800°C or more and is made of a composition capable of reducing heat transfer due to radiation, but infrared reflective materials are preferred. Examples of such compositions include silicon carbide, titanium dioxide, iron, zirconium silicate, zirconia, etc., and it is preferable to use one or more selected from the group consisting of these compositions. In addition, the infrared scattering material preferably has an average particle size of 0.1 μm or more and 3.0 μm or less.

[0019] The above-mentioned refractory fiber is a fiber made of an inorganic composition having a heat resistance temperature of about 600 to 1600°C. The material thereof is not limited, but examples thereof include glass fiber, alumina fiber, mullite fiber, calcia hexaaluminate (CaO 6Al2O3) fiber, zirconia fiber, biosoluble fiber, and alkaline earth silicate (AES) fiber. It is preferable to use one or more types selected from the group consisting of these fibers.

[0020] The average fiber diameter of the above-mentioned refractory fiber is preferably 1 μm or more and 13 μm or less, more preferably 2 μm or more and 10 μm or less. In this specification, the average fiber diameter is the arithmetic average of the distances in the width direction of 200 or more fibers arbitrarily selected from the image obtained by photographing the fiber group to be measured with an electron microscope. The above-mentioned refractory fiber may contain non-fibrous particles of the same material. In this case, the content of the non-fibrous particles is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, relative to 100 parts by mass of the refractory fiber contained in the above-mentioned molded body. In particular, the amount of non-fibrous particles having an average particle diameter of 425 μm or more is preferably 3 parts by mass or less, more preferably 1 part by mass or less.

[0021] The porous insulating aggregate is preferably made of a highly heat-resistant composition having a heat-resistant temperature of 1200°C or more, and has a porous structure with numerous pores having a pore diameter of about 500 to 1000 nm. For example, when the maximum use temperature of the microporous insulating material is 1200°C, it is preferable to use an insulating aggregate having a heat-resistant temperature of 1200°C or more, and when the maximum use temperature of the microporous insulating material is 1400°C, it is preferable to use an insulating aggregate having a heat-resistant temperature of 1400°C or more. Examples of such insulating aggregates are not limited, but examples of insulating aggregates having a heat-resistant temperature of 1400°C or more include spinel ceramics (Thermoscatt (registered trademark) manufactured by CoorsTek Corporation) and CaO·6Al2O3 (calcia hexaaluminate) ceramics (SLA-92 manufactured by Almatis Co., Ltd.), and examples of insulating aggregates having a heat-resistant temperature of 1200°C or more include porous alumina.

[0022] The sheet-shaped microporous heat insulating material consisting of the above various components is appropriately determined in terms of the mixing ratio of these components (i.e., each content) so as to obtain the desired characteristics, taking into consideration the action and effect of each of the above components. In general, it is preferable to contain 35 to 75 parts by mass, more preferably 40 to 60 parts by mass, 10 to 30 parts by mass of refractory fiber, 8 to 20 parts by mass of infrared scattering material, and 3 to 40 parts by mass of organic fiber, relative to 100 parts by mass of the microporous heat insulating material. The total content of these components is preferably 98 parts by mass or more, and conversely, additives such as inevitable impurities and molding aids may be contained in the microporous heat insulating material as long as the total amount is less than 2 parts by mass.

[0023] The above-mentioned sheet-shaped microporous insulation material has a bulk density of 200 to 500 kg / m 3 It is preferable that the thickness is 250 to 300 kg / m 3 It is more preferable that the bulk density is 200 kg / m 3 If the bulk density is less than 500 kg / m, sufficient strength cannot be obtained and handling properties may be insufficient. 3 If it exceeds this value, the strength will be too high and good flexibility may not be obtained. It is preferable that this sheet-shaped microporous insulation material has a thermal conductivity of 0.10 W / (m·K) or less at 600°C. If it exceeds 0.10 W / (m·K), it is not much different from the thermal conductivity of the ceramic fiber insulation material described below, which is 0.13 W / (m·K) at 600°C, so the advantage of forming it into a composite insulation sheet is not realized.

[0024] The sheet-shaped ceramic fiber insulation material, which is another component of the embodiment of the composite heat insulating sheet according to the present invention, is preferably an insulation material made of one or more materials selected from mullite fiber, alumina fiber, alkaline earth silicate (AES) fiber, and alumina-silica fiber. This sheet-shaped ceramic fiber insulation material can be a blanket manufactured by laminating bulk fibers obtained by fiberizing a molten raw material by a blowing method or a spinning method into layers and then needle punching the fibers to intricately entangle them. The expression "fiber" above means that the material indicated by "-" is the main component, and that a secondary component may be included.

[0025] The ceramic fiber, which is the material of the ceramic fiber insulation material, preferably has an average fiber diameter of 1 μm or more and 13 μm or less, more preferably 2 μm or more and 10 μm or less. The ceramic fiber may also contain non-fibrous particles of the same material. In this case, the content of the non-fibrous particles is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, per 100 parts by mass of the ceramic fiber contained in the ceramic fiber insulation material. In particular, the content of non-fibrous particles having an average particle diameter of 425 μm or more is preferably 3 parts by mass or less, more preferably 1 part by mass or less.

[0026] The bulk density of the ceramic fiber insulation material is 100 to 200 kg / m 3 is preferable, and 130 to 170 kg / m 3 It is more preferable that the bulk density is within the above range. In both cases where the bulk density is outside the above range and is smaller or larger, the thermal conductivity increases, and the thermal insulation properties may decrease. It is preferable that the above ceramic fiber insulation material has a thermal conductivity of 0.38 W / (m K) or less at 800°C and a thermal conductivity of 0.13 W / (m K) or less at 600°C.

[0027] The sheet-like ceramic fiber insulation material is bonded to the surface opposite to the application surface of the sheet-like microporous insulation material described above. This allows the manufacture of a two-layer composite insulation sheet in which two types of insulation materials are integrated. The above-mentioned bonding method can be exemplified by a method in which an inorganic adhesive is applied to the cold surface side of the ceramic fiber insulation material and / or the hot surface side of the microporous insulation material to bond them together. Since both of these sheet-like microporous insulation materials and sheet-like ceramic fiber insulation materials have flexibility, the two-layer composite insulation sheet obtained by integrating them also has flexibility. It is preferable to appropriately select the thickness and number of layers of each of these sheet-like microporous insulation materials and sheet-like ceramic fiber insulation materials according to the use temperature of the application surface and the curvature of the curved surface. Next, the composite insulation sheet of the present invention will be described in more detail with reference to examples and comparative examples. EXAMPLES

[0028] Composite insulation sheets according to the examples and comparative examples of the present invention shown below were produced and used to line the inner wall surface of an electric furnace body composed of curved surfaces. The bulk density, flexibility, radius of curvature, compressive strength, insulation, and heat resistance of the insulation materials used were determined by the following methods. That is, bulk density was determined by dividing mass by volume. Flexibility was determined in a three-point bending test using a strength testing machine, by pressing down on the center of a 5 mm thick test piece placed on two supports spaced apart by a distance (span) of 100 mm, and measuring the maximum amount of deflection when the test piece broke. The radius of curvature was determined as the radius of curvature at which a break occurred when the 5 mm thick test piece was bent. Compressive strength was determined using the "compressive strength [N / mm 2 ] = (Maximum load (N) when the test piece is compressed by 10%) / area (mm 2 ) and was calculated from the maximum load when a specimen was compressed using a strength testing machine to reach a strain of 10%. Thermal insulation was determined by measuring thermal conductivity at 600°C in accordance with the plate comparison method (JIS A1412-2, Appendix A). Heat resistance was determined as the heat resistance temperature at which the linear heat shrinkage rate becomes 4% or less when the test specimen is heated for 24 hours.

[0029] [Example 1] The following mixtures were charged into a mixer and mixed at a blending ratio of 65% by mass of silica fine particles (average particle size 0.2 μm) as inorganic fine particles, 10% by mass of glass fiber (E glass, average fiber diameter 13 μm) as fire-resistant fiber, 15% by mass of silicon carbide particles (average particle size 2 μm) as infrared scattering material, and 10% by mass of polyethylene / polypropylene core-sheath structure fiber (fiber diameter 1.7 dtex, fiber length 5 mm) as organic fiber. The resulting mixture was charged into a mold and compression molded into a thin sheet, which was then heated and compression molded at 150°C. The resulting sheet-shaped microporous insulation material with a thickness of 5 mm had a bulk density of 300 kg / m 3 The deflection was 9.6 mm, the radius of curvature was 129 mm, the compressive strength was 0.78 MPa, the thermal conductivity was 0.03 W / (m·K), and the heat resistance temperature was 1000°C.

[0030] On the other hand, the sheet-type ceramic fiber insulation material is an alumina fiber manufactured by Denka Co., Ltd., with a thickness of 25 mm and a bulk density of 130 kg / cm. 3 A blanket (Denka Arsen (registered trademark)) made by Sakai Chemical Industry Co., Ltd. was used. An inorganic heat-resistant adhesive (Betac 1200) made by Sakai Chemical Industry Co., Ltd. was applied to one side of this sheet-like ceramic fiber insulation material, and the above-mentioned sheet-like microporous insulation material was attached to it. When the composite insulation sheet made in this way, consisting of a sheet-like ceramic fiber insulation material 1 and a sheet-like microporous insulation material 2 as shown in FIG. 1, was installed to line the iron shell 3 of an electric furnace body composed of a curved surface, the attached portion was not peeled off or damaged, and the electric furnace could be well insulated for a long period of time.

[0031] [Example 2] A sheet-shaped ceramic fiber insulation material is covered with a mullite fiber blanket manufactured by Isolite Kogyo Co., Ltd. (product name Fibermax 1600 blanket, thickness 25 mm, bulk density 130 kg / cm3). 3A composite heat insulating sheet was produced in the same manner as in Example 1 above, except that ), and was applied in the same manner as in Example 1 above. During application, the bonded portions were not peeled off or damaged, and the electric furnace was well insulated for a long period of time.

[0032] [Example 3] The sheet-shaped ceramic fiber insulation is covered with an AES (alkaline earth silicate) fiber blanket manufactured by Isolite Industries Co., Ltd. (product name: BSSR1300 blanket, thickness 25 mm, bulk density 130 kg / cm3). 3 A composite heat insulating sheet was produced in the same manner as in Example 1 above, except that ), and was applied in the same manner as in Example 1 above. During application, the bonded portions were not peeled off or damaged, and the electric furnace was well insulated for a long period of time.

[0033] [Example 4] A sheet-shaped ceramic fiber insulation material is covered with an alumina-silica fiber blanket manufactured by Isolite Industries Co., Ltd. (product name: Isowool 1400 Blanket, thickness 25 mm, bulk density 130 kg / cm3). 3 A composite heat insulating sheet was produced in the same manner as in Example 1 above, except that ), and was applied in the same manner as in Example 1 above. During application, the bonded portions were not peeled off or damaged, and the electric furnace was well insulated for a long period of time.

[0034] [Example 5] A sheet-shaped ceramic fiber insulation material is covered with an alumina-silica fiber blanket manufactured by Isolite Industries Co., Ltd. (product name: Isowool 1400 Blanket, thickness 12.5 mm, bulk density 130 kg / cm3). 3 ) and a mullite fiber blanket manufactured by Isolite Industries Co., Ltd. (product name Fibermax 1600 blanket, thickness 12.5 mm, bulk density 130 kg / cm 3A composite heat insulating sheet was produced in the same manner as in Example 1 above, except that the composite heat insulating sheet was made by bonding the two sheets together with an inorganic heat-resistant adhesive (Betac 1200) manufactured by Sakai Chemical Industry Co., Ltd., and was applied in the same manner as in Example 1 above. During application, the bonded portions were not peeled off or damaged, and the electric furnace was well insulated for a long period of time.

[0035] [Example 6] As inorganic fine particles, 60% by mass of alumina fine particles (average particle size 18 nm), 5% by mass of mullite fiber (average fiber diameter 5 μm) as refractory fiber, 15% by mass of zirconium silicate particles (average particle size 1 μm) as infrared scattering material, 10% by mass of polyethylene / polypropylene core-sheath structure fiber (fiber diameter 1.7 dtex, fiber length 5 mm) as organic fiber, and 10% by mass of spinel ceramics (Thermoscatt (registered trademark), average particle size 8000 nm) manufactured by CoorsTek Corporation as refractory aggregate were charged into a mixer and mixed. The obtained mixture was charged into a mold and compression molded to form a thin sheet, and then heated and compressed at 150 ° C. The obtained sheet-shaped microporous insulation material with a thickness of 5 mm had a bulk density of 400 kg / m 3 The results were: deflection 9.6 mm, radius of curvature 129 mm, compressive strength 0.78 MPa, thermal conductivity 0.10 W / (m K), and heat resistance temperature 1400°C. A composite insulation sheet was produced in the same manner as in Example 1 above, and installed in the same manner as in Example 1 above. During installation, the bonded parts did not peel off or become damaged, and the electric furnace was well insulated for a long period of time.

[0036] [Comparative Example] The sheet-shaped ceramic fiber insulation is covered with an AES (alkaline earth silicate) fiber blanket manufactured by Isolite Kogyo Co., Ltd. (product name: BSSR1300 blanket, thickness 25 mm, bulk density 130 kg / cm3). 3) was used, one side of which was coated with the same adhesive as that used in Example 1, and a heat insulating sheet (5 mm thick) made of a commercially available flexible microporous heat insulating material packed in a polyethylene film was attached to it to produce a composite heat insulating sheet. When an attempt was made to line the steel shell of an electric furnace body composed of curved surfaces with this composite heat insulating sheet as in Example 1 above, the heat insulating sheet was damaged internally. [Explanation of symbols]

[0037] 1. Sheet-type ceramic fiber insulation 2. Sheet-type microporous insulation material 3 Ironhide

Claims

1. A flexible two-layer composite insulation sheet that combines sheet-shaped ceramic fiber insulation material and sheet-shaped microporous insulation material in which organic fibers are mixed with inorganic fine particles as the main material.

2. The composite insulation sheet described in claim 1, characterized in that the microporous insulation material has a thermal conductivity of 0.10 W / (m・K) or less at 600°C, and when a 5 mm thick piece is measured for bending strength with a span of 100 mm, the deflection at break is 3.0 mm or more and 10.0 mm or less.

3. 3. The composite insulation sheet according to claim 1 or 2, characterized in that the ceramic fiber insulation material is made of one or more materials selected from the group consisting of mullite fiber, alumina fiber, alkaline earth silicate fiber, and alumina-silica fiber.

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