Composite heat insulating material

Abstract

To provide a composite heat insulating material capable of being simply constructed on a construction surface composed of a curve surface.SOLUTION: A two-layer composite heat insulating material has a two-layer structure in which a 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 and having a curved cold surface is integrated with a flexible molded body that is made of a microporous heat insulating material 2, which has inorganic fine particles mixed with organic fibers as a main material, and which can be joined along the curved cold surface. Preferably, the microporous heat insulating material has a thermal conductivity of 0.05 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 two-layer composite insulation material, and more particularly to a composite insulation material that can be easily applied to surfaces including many curved surfaces, such as the walls of industrial furnaces, and that combines excellent insulation and heat resistance. [Background technology]

[0002] Industrial furnaces such as heating furnaces, heat treatment furnaces, drying furnaces, boilers, kilns, and incinerators are used in various industrial fields such as metal smelting, petrochemicals, and ceramics. In these industrial furnaces and their peripheral equipment, insulation is installed as an inner lining on the inside of the furnace body and the inner surface of ducts and chimneys to suppress heat loss to the outside due to radiation, etc., and to reduce energy consumption as much as possible. In addition, in components through which cooling water flows, such as the skid posts in walking beam heating furnaces, insulation is installed as an outer lining on the outside of the components to prevent the cooling water from being heated by heat input from the outside.

[0003] The heated surfaces of equipment and devices used in high-temperature atmospheres, such as the above-mentioned furnace walls of industrial furnaces, the inner surfaces of ducts, and the outer peripheral surfaces of skid posts, are often curved, and therefore the insulating material is required to be suitable for application to curved surfaces. In order to meet this demand, products that can be freely bent along the heated surfaces that are curved have been proposed. For example, Non-Patent Documents 1 and 2 disclose a technique for producing insulating materials in various forms, such as futon-shaped, quilt-shaped, and segmented, by covering a microporous insulating material made of nano-sized silica particles with a fiber covering material and sewing it. However, in these forms of insulating materials, the microporous insulating material itself does not exist in the sewn parts, or the thickness is thinner than other parts, so there is a risk of insufficient insulation.

[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, which is the surface to be heated, becomes 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 cutting, drilling, and other processing 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] Meanwhile, heat insulating materials applied to parts exposed to high-temperature atmospheres, such as the furnace body of an industrial furnace, are required to have high heat resistance as well as high heat insulation. As a result of extensive research by the inventors to meet these requirements, they have found that since ceramic fiber heat insulating materials have slightly lower thermal conductivity than microporous heat insulating materials but have excellent heat resistance, it is effective to use a two-layer structure in which ceramic fiber heat insulating materials are used on the hot side and microporous heat insulating materials on the cold side.

[0007] However, when making a two-layered insulation, the microporous insulation must first be fixed to the surface to be installed, such as the steel shell, and then the ceramic fiber insulation must be attached to that surface, which is a concern as it takes time and effort to install. After further investigation, we came to the conclusion that it would be easier to install if these two types of insulation were combined and integrated in advance. In this case, in order to make a composite insulation that can be installed on curved surfaces, the microporous insulation is attached to the curved surface of the ceramic fiber insulation that faces the installation surface. However, since microporous insulation, which is made by compressing inorganic fine particles into a plate shape, generally has poor flexibility, there was a risk of damage to the microporous insulation when it was bent to fit the curved surface of the ceramic fiber insulation.

[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 two-layer composite insulating material 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 composite insulation material of the present invention is characterized by having a two-layer structure that integrates a ceramic fiber insulation material whose cold side is curved, and a molded body made of a microporous insulation material in which organic fibers are mixed with inorganic fine particles as the main material, and which has flexibility that allows it to be joined along the curved surface. Effect of the Invention

[0010] According to the present invention, it is possible to easily carry out construction even on surfaces that are curved, such as the inner wall surfaces of industrial furnaces and the skid posts of walking beam type heating furnaces. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view showing a composite insulation material according to an embodiment of the present invention used as an interior lining insulation material (a) and as an exterior lining insulation material (b). [Diagram 2] FIG. 2 is a perspective view of a block made of the ceramic fiber heat insulating material produced in Examples 1 to 5. [Diagram 3] FIG. 3 is a perspective view of a composite insulation material made using the blocks of FIG. 2. [Figure 4] FIG. 1 is an oblique view of a block made of ceramic fiber insulation material produced in Example 6. [Diagram 5] FIG. 5 is a perspective view of a composite insulation material made using the blocks of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the composite heat insulating material according to the present invention will be described. The composite heat insulating material according to the embodiment of the present invention is suitable for heat insulating application to surfaces constituted by curved surfaces such as the furnace body of an industrial furnace or the skid post of a walking beam type heating furnace, and has a two-layer structure in which a ceramic fiber heat insulating material with a curved cold surface side so that it can be applied along the application surface without gaps, and a molded body made of a microporous heat insulating material in which organic fibers are mixed with inorganic fine particles as a main material, and has flexibility so that it can be bonded along the curved cold surface side of the ceramic fiber heat insulating material are integrated.

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

[0014] The microporous insulation material is produced by mixing the inorganic fine particles, organic fibers, and other raw materials in a predetermined ratio, placing the resulting mixture in a mold, compressing and molding it, and then heating it to about 150°C and compressing it. In this way, the molded body of the microporous insulation material is produced through heated compression molding, and has a structure in which the organic fibers are 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] In this way, the molded body of the microporous thermal insulation material, which is one component of the composite thermal insulation material according to the embodiment of the present invention, has flexibility and can be easily curved without breaking even when applied to a curved surface with a curvature radius of about 125 mm. The above-mentioned amount of deflection can be changed by appropriately adjusting the material and form of the organic fiber blended into the microporous thermal insulation material, the blending ratio, and molding conditions such as the heating temperature during heat compression molding and the holding time.

[0016] The above microporous insulation material has a thermal conductivity of 0.05 W / (m·K) or less at 600°C, and by including an infrared scattering material, the thermal conductivity at 600°C can be reduced to 0.03 W / (m·K) due to the synergistic effect of these inorganic particles and the infrared scattering material. In addition, the above microporous insulation material has a heat resistance of up to 1000°C.

[0017] 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%.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The microporous heat insulating material consisting of the above various components is appropriately determined in terms of the mixing ratio of these components (i.e., the content of each component) so as to obtain the desired characteristics, taking into consideration the action and effect of each component. 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 molded body made of the microporous thermal 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 may be too high and good flexibility may not be obtained.

[0024] The ceramic fiber insulation, which is another component of the embodiment of the composite insulation according to the present invention, is preferably an insulation material made of one or more of mullite fiber, alumina fiber, alkaline earth silicate (AES) fiber, and alumina-silica fiber. The form of this ceramic fiber insulation material may be a block made by folding or stacking a blanket-like product, or a block manufactured by a vacuum forming method using ceramic fiber as a base material. 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 100-200kg / m in the case of a block made of laminated blanket-like products. 3 is preferable, and 130 to 170 kg / m 3 On the other hand, in the case of a block manufactured by the vacuum forming method using ceramic fiber as a base material, the maximum load is 200 to 500 kg / m 3 is preferable, and 220 to 350 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 ceramic fiber insulation material has a thermal conductivity of 0.38 W / (m K) or less at 800°C.

[0027] The ceramic fiber insulation material is bonded to the surface opposite to the application surface of the molded body made of the microporous insulation material. This makes it possible to manufacture a composite insulation material with a two-layer structure in which two types of insulation materials are integrated. As the above-mentioned bonding method, a method of applying an inorganic adhesive to the cold surface side of the ceramic fiber insulation material and / or the hot surface side of the microporous insulation material and bonding them can be mentioned. In this case, even if the back surface of the ceramic fiber insulation material, which is the surface opposite to the surface side facing the high temperature atmosphere (i.e., the cold surface side facing the application surface), is a curved surface, the molded body made of the microporous insulation material has flexibility, so that it can be easily combined and integrated. Alternatively, as another bonding method, a metal support may be built into the ceramic fiber insulation material, and the molded body of the microporous insulation material may be fixed by this metal support. It is preferable to appropriately select the thickness and number of layers of the molded body made of the microporous insulation material according to the operating temperature of the industrial furnace to be installed.

[0028] When the composite heat insulating material according to the embodiment of the present invention is used for lining the inside of an iron shell such as the furnace wall of an industrial furnace, the hot surface side on which the ceramic fiber heat insulating material 1 is located is inside the molded body 2 made of a microporous heat insulating material as shown in FIG. 1(a), and when it is used for lining a member through which cooling water flows such as a skid post, the hot surface side on which the ceramic fiber heat insulating material 1 is located is outside the molded body 2 made of a microporous heat insulating material as shown in FIG. 1(b). In either case, the molded body made of a microporous heat insulating material is attached to the application surface of the iron shell or the like with metal fittings or the like, and the ceramic fiber heat insulating material is bonded in advance to the surface of the molded body made of the microporous heat insulating material opposite to the surface facing the application surface with an adhesive or the like. Next, the composite heat insulating material of the present invention will be described in more detail with reference to examples and comparative examples. EXAMPLES

[0029] Composite insulation materials according to the examples and comparative examples of the present invention shown below were prepared and applied to the exterior of the skid posts of a walking beam type heating furnace. The bulk density, flexibility, radius of curvature, compressive strength, thermal 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 by measuring the maximum amount of deflection when a 5 mm thick test piece placed on two supports spaced apart by a distance (span) of 100 mm was pushed down on the center of the test piece to break it in a three-point bending test using a strength testing machine. The radius of curvature was determined as the radius of curvature at which a 5 mm thick test piece broke when it 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 produce a 10% strain. Thermal insulation was determined by measuring thermal conductivity at 600°C in accordance with the flat plate comparison method (JIS A1412-2 Appendix A). Heat resistance was determined as the maximum temperature at which the linear thermal shrinkage rate was 3% or less when the test specimen was heated for 24 hours.

[0030] [Example 1] The mixture was mixed in a mixer 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 mixture obtained was placed in a mold and compression molded into a thin sheet, which was then heated and compression molded at 150°C to produce a sheet-like molded body with a thickness of 5 mm. The obtained molded body made of sheet-like microporous insulation material 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.

[0031] On the other hand, an alumina fiber blanket (Denka Arsen (registered trademark)) manufactured by Denka Co., Ltd. was prepared as a ceramic fiber insulation material, which was laminated to form a module and then cut into a half-ring shape. This resulted in a 300 mm thick insulation material with a bulk density of 130 kg / cm3 as shown in FIG. 3 A block with an inner radius of curvature of 200 mm was prepared. An inorganic heat-resistant adhesive (Betac 1200) manufactured by Sakai Chemical Industry Co., Ltd. was applied to the inner curved surface of this block, and the sheet-shaped molded body made of the above-mentioned microporous thermal insulation material was curved and bonded to it as shown in Figure 3(a).

[0032] As shown in Figure 3(b), a pair of the composite insulation materials prepared above was used to sandwich a skid post having a curved outer periphery, with the microporous insulation sides facing each other, and the skid post was then covered with the composite insulation material. During the installation of the composite insulation material, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was well insulated for a long period of time.

[0033] [Example 2] A modularized block made by layering and compressing a mullite fiber blanket manufactured by Isolite Industries Co., Ltd. onto a block of ceramic fiber insulation (product name Fibermax 1600 Uniblock, thickness 300 mm, bulk density 130 kg / cm). 3 A composite insulation material was prepared in the same manner as in Example 1 above, except that the microporous insulation material was cut so that the radius of curvature of the inner curved surface was 200 mm, and a skid post was exteriorly installed in the same manner as in Example 1 above. During this installation, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was able to be well insulated for a long period of time.

[0034] [Example 3] A modularized block (product name BSSR1300 Uniblock, thickness 300mm, bulk density 130kg / cm) made by layering and compressing an AES (alkaline earth silicate) fiber blanket manufactured by Isolite Industries Co., Ltd. onto a block of ceramic fiber insulation material. 3 A composite insulation material was prepared in the same manner as in Example 1 above, except that the microporous insulation material was cut so that the radius of curvature of the inner curved surface was 200 mm, and a skid post was exteriorly installed in the same manner as in Example 1 above. During this installation, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was able to be well insulated for a long period of time.

[0035] [Example 4] A modularized block made by layering and compressing an alumina-silica fiber blanket manufactured by Isolite Industries Co., Ltd. onto a block of ceramic fiber insulation material (product name: Isowool 1400 Uniblock, thickness 300 mm, bulk density 130 kg / cm). 3 A composite insulation material was prepared in the same manner as in Example 1 above, except that the microporous insulation material was cut so that the radius of curvature of the inner curved surface was 200 mm, and a skid post was exteriorly installed in the same manner as in Example 1 above. During this installation, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was able to be well insulated for a long period of time.

[0036] [Example 5] A ceramic fiber insulation block 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 ) and a mullite fiber blanket manufactured by Isolite Industries Co., Ltd. (product name Fibermax 1600, blanket thickness 25 mm, bulk density 130 kg / cm 3A composite insulation material was produced in the same manner as in Example 1 above, except that a modularized block made by alternately laminating the microporous insulation materials was used, which was then cut so that the radius of curvature of the inner curved surface was 200 mm, and a skid post was then exterior-covered in the same manner as in Example 1 above. During this construction, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was able to be well insulated for a long period of time.

[0037] [Example 6] A block of ceramic fiber insulation material with alumina and silica fiber formed by vacuum forming (product name: Isowool 1400VFS, thickness 300mm, bulk density 300kg / cm) manufactured by Isolite Kogyo Co., Ltd. 3 A composite insulation material as shown in Fig. 5(a) was produced in the same manner as in Example 1 above, except that a block of the microporous insulation material was used, in which the inner curved surface was cut to have a curvature radius of 200 mm as shown in Fig. 5. A pair of these composite insulation materials was used to cover the exterior of a skid post, as shown in Fig. 5(b). During this installation, the sheet-shaped microporous insulation material was not peeled off or damaged, and the skid post was able to be well insulated for a long period of time.

[0038] [Comparative Example] As a ceramic fiber insulation material, 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) was used. 3 ) was prepared, and these were laminated to form a modular block, which was then cut to a radius of curvature of the inner curved surface of 200 mm. The same adhesive as used in Example 1 was applied to this inner curved surface, and an attempt was made to produce a composite insulation material by bonding an insulation sheet (thickness 5 mm) made of a commercially available flexible microporous insulation material packed in a polyethylene film; however, the insulation sheet broke when it was bent to fit the inner curved surface of the ceramic fiber insulation block. [Explanation of symbols]

[0039] 1. Ceramic fiber insulation 2. Molded body made of microporous insulation material

Claims

1. A two-layer composite insulation material that integrates a ceramic fiber insulation material with a curved cold surface and a microporous insulation material in which organic fibers are mixed with inorganic fine particles as the main material, and a flexible molded body that can be joined along the curved surface.

2. The composite insulation material described in claim 1, characterized in that the microporous insulation material has a thermal conductivity of 0.05 W / (m・K) or less at 600°C, and when a 5 mm thick material 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 material 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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