Refractory heat insulation sheet

Abstract

To provide a fireproof heat insulation sheet with excellent refractory and adiabaticity.SOLUTION: A fireproof heat insulation sheet comprises: a heat insulation layer having a porous structure in which a plurality of particles is connected to form a skeleton, has pores inside, and has a hydrophobic site at least on the surface and inside; a first refractory layer made of a heat-resist fiber sheet, which is arranged on one side in a thickness direction of the heat insulation layer; and a second refractory layer laminated on the first refractory layer, and having one or more flame retardants selected from an intumescent flame retardant and expanded graphite, and an organic binder.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a refractory heat-insulating sheet using a porous structure such as silica aerogel.

Background Art

[0002] In the construction field, refractory sheets are used for building materials such as steel frames and wall materials to protect buildings from flames and heat during a fire. For example, Patent Document 1 describes a refractory sheet manufactured from a foaming fire-resistant powder having a flame retardant, a foaming agent, a carbonizing agent, and a filler, and a thermoplastic resin. When this type of refractory sheet is heated, the contained components foam, and thereby an incombustible carbonized layer is formed by expansion, thereby exhibiting refractory heat-insulating performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of a conventional refractory sheet, in order to exhibit refractory and heat insulation performance, a space for the sheet to expand in the thickness direction is required. Therefore, in places where there are restrictions on space, the expansion of the sheet is restricted and a carbonized layer cannot be sufficiently formed, making it difficult to apply. For example, building materials have a reduced mechanical strength when exposed to high temperatures. For this reason, as a role of the refractory sheet, it is important not only to suppress ignition in the object to be protected but also to suppress the temperature rise. Also, when applying the refractory sheet to a fuel tank or a battery housing mounted on an automobile, it is important to suppress heat transfer and thus suppress the temperature rise. In this regard, since the conventional refractory sheet is mainly aimed at fire prevention, its heat insulation property is not sufficient, and it is difficult to suppress the temperature rise of the object to be protected.

[0005] On the other hand, as a heat insulating material, one using silica aerogel with a low thermal conductivity is known. For example, Patent Document 2 describes a composite material including an insulating base layer containing silica aerogel and an aqueous binder, and a heat reflective top layer containing a protective binder and an infrared reflective agent. Paragraph

[0034] of Patent Document 2 and the like describe a form in which a flame retardant is compounded in each layer. Also, Patent Document 3 describes a heat insulating sheet including a film base material, an adhesive layer, and a heat insulating layer containing silica aerogel. Paragraph

[0036] of Patent Document 3 and the like describe a form in which a flame retardant is compounded in the heat insulating layer.

[0006] However, when a flame retardant is compounded in the heat insulating layer, the compounding ratio of silica aerogel decreases accordingly, leading to a decrease in heat insulation performance. Also, simply compounding a flame retardant in the heat insulating layer may expose the heat insulating layer to the flame during a fire and cause it to reach a high temperature, potentially impairing the heat insulating function.

[0007] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a refractory heat insulating sheet having excellent fire resistance and heat insulation performance.

Means for Solving the Problems

[0008] In order to solve the above problems, the fire-resistant insulation sheet of the present disclosure is characterized by comprising an insulation layer having a porous structure in which a plurality of particles are connected to form a skeleton, which has pores inside, and which has hydrophobic portions on at least the surface of the surface and inside; a first fire-resistant layer arranged on one side of the thickness direction of the insulation layer and made of a heat-resistant fiber sheet; and a second fire-resistant layer laminated to the first fire-resistant layer and containing one or more flame retardants selected from an intumescent flame retardant and an expandable graphite, and an organic binder. [Effects of the Invention]

[0009] The fire-resistant and insulating sheet of the present disclosure has a three-layer structure consisting of an insulating layer, a first fire-resistant layer, and a second fire-resistant layer. In the fire-resistant and insulating sheet of the present disclosure, multiple layers are stacked to separate the functions of fire resistance and insulation. The fire-resistant and insulating sheet of the present disclosure is arranged so that the insulating layer is on the side to be protected and the second fire-resistant layer is on the outside. The first and second fire-resistant layers have excellent fire resistance and primarily suppress flame penetration. The insulating layer has excellent insulating properties and primarily suppresses heat transfer. When heated, the second fire-resistant layer expands due to the action of the flame retardant, forming a non-combustible layer. Therefore, the second fire-resistant layer has excellent insulating properties in addition to fire resistance. By stacking these layers with different functions, a fire-resistant and insulating sheet with excellent fire resistance and insulation properties can be achieved, even if the thickness of each layer is reduced and the overall thickness of the sheet is thin. The fire-resistant and insulating sheet of the present disclosure is thin, relatively flexible, and lightweight. This makes it easy to install, suitable for use in relatively narrow spaces, and suitable for vehicle parts that require lightweight construction. [Brief explanation of the drawings]

[0010]

Figure 1

Figure 2

[0011] Hereinafter, an embodiment of the fire-resistant heat insulating sheet of the present disclosure will be described.

[0012] <First Embodiment> [Configuration] First, the configuration of the fireproof heat insulation sheet of this embodiment will be described. FIG. 1 shows a cross-sectional view of the fireproof heat insulation sheet of this embodiment in the thickness direction. In FIG. 1, the thickness direction (lamination direction) is shown as the inside-outside direction. The inside corresponds to the side of the object to be protected. As shown in FIG. 1, the fireproof heat insulation sheet 10 includes a heat insulation layer 11, a first fireproof layer 12, and a second fireproof layer 13 in order from the inside. The thickness of the fireproof heat insulation sheet 10 is 2.5 mm.

[0013] The heat insulation layer 11 has silica aerogel, a urethane resin as a binder, and carboxymethyl cellulose (CMC) as a thickener. Silica aerogel is included in the concept of the "porous structure" in the present disclosure. The thickness of the heat insulation layer 11 is 1 mm. The heat insulation layer 11 is adhered to an object to be protected such as a fuel tank.

[0014] The first fireproof layer 12 is disposed on one surface (one surface in the thickness direction) outside the heat insulation layer 11. The first fireproof layer 12 is made of a heat-resistant non-woven fabric containing glass fibers. The heat-resistant non-woven fabric has a fire resistance such that it does not have holes even when exposed to a 1000 °C flame for 5 minutes. The heat-resistant non-woven fabric is included in the concept of the "fiber sheet having heat resistance" in the present disclosure. The thickness of the first fireproof layer 12 is 0.5 mm.

[0015] The second fireproof layer 13 is disposed on one surface outside the first fireproof layer 12. The second fireproof layer 13 has ammonium polyphosphate and a urethane resin. When the total mass of the second fireproof layer 13 is 100% by mass, the content of ammonium polyphosphate is 45% by mass. Ammonium polyphosphate is included in the concept of the "intumescent flame retardant" in the present disclosure. The urethane resin is included in the concept of the "organic binder" in the present disclosure. The thickness of the second fireproof layer 13 is 1 mm.

[0016] [Manufacturing Method] Next, a method for manufacturing the refractory heat-insulating sheet of the present embodiment will be described. First, a urethane resin emulsion and CMC are added to water and stirred, and then silica aerogel is added and stirred to prepare a composition for the heat-insulating layer. Also, a urethane resin emulsion and ammonium polyphosphate powder are added to water and stirred to prepare a composition for the second refractory layer. Next, the prepared composition for the heat-insulating layer is applied to one surface (inner surface) of the heat-resistant nonwoven fabric as the first refractory layer 12 and dried to form the heat-insulating layer 11. Then, the prepared composition for the second refractory layer is applied to the other surface (outer surface) of the heat-resistant nonwoven fabric and dried to form the second refractory layer 13.

[0017] [Function and Effect] Next, the function and effect of the refractory heat-insulating sheet of the present embodiment will be described. Since the heat-insulating layer 11 in the refractory heat-insulating sheet 10 has silica aerogel, it has excellent heat-insulating properties. Also, by using a urethane resin as a binder, it is possible to suppress the dropout of silica aerogel and impart flexibility to the heat-insulating layer 11. Further, by using CMC as a thickener, the viscosity of the composition for the heat-insulating layer increases. As a result, the water suspension property of the hydrophobic silica aerogel is improved, making it easier for the silica aerogel to disperse and improving the coatability. In addition, flexibility can be imparted to the heat-insulating layer 11.

[0018] When the second refractory layer 13 is heated, ammonium polyphosphate decomposes to generate gas, and as a result, the carbonized layer formed from carbon generated from organic compounds such as urethane resin expands to form a porous expanded incombustible layer. In the refractory heat-insulating sheet 10, the intrusion of flames is suppressed by these two layers, namely, the second refractory layer 13 and the first refractory layer 12 having a high heat resistance and an excellent flame-blocking effect. Therefore, even if the amount of the flame retardant (ammonium polyphosphate) in the second refractory layer 13 is relatively small, the desired fire resistance can be achieved. Thus, the space required for the expansion of the second refractory layer 13 may be relatively small. Further, since the two layers of the second refractory layer 13 and the first refractory layer 12 are arranged outside the heat-insulating layer 11, the heat-insulating layer 11 is less likely to be exposed to flames, and the heat-insulating function can be maintained. In this way, according to the refractory heat-insulating sheet 10, by laminating three layers with different functions, even if the overall thickness is thin, the desired fire resistance and heat insulation can be achieved. The refractory heat-insulating sheet 10 is thin, relatively flexible, and lightweight, so it has excellent workability and can be applied to relatively narrow places.

[0019] <Second Embodiment> The difference between the refractory heat-insulating sheet of this embodiment and the refractory heat-insulating sheet of the first embodiment is that a cover layer is arranged on the surface (the other surface in the thickness direction) on the protected object side of the heat-insulating layer. Here, the description will be centered on the differences. FIG. 2 shows a cross-sectional view of the refractory heat-insulating sheet of this embodiment in the thickness direction. As shown in FIG. 2, the refractory heat-insulating sheet 20 includes a cover layer 24, a heat-insulating layer 21, a first refractory layer 22, and a second refractory layer 23 in order from the inside. The thickness of the refractory heat-insulating sheet 20 is 2.8 mm. Since the configurations and thicknesses of the layers other than the cover layer 24 are the same as those of the first embodiment, the description thereof is omitted.

[0020] The cover layer 24 is made of a polyester fiber non-woven fabric with a thickness of 0.3 mm. The cover layer 24 is adhered to the object to be protected such as a fuel tank. According to the refractory heat-insulating sheet 20, since the heat-insulating layer 21 is covered by the cover layer 24, the effect of suppressing the dropout of silica aerogel is high, and the handleability is improved.

[0021] The manufacturing method of the refractory heat insulation sheet 20 is as follows. First, in the same manner as in the first embodiment, a composition for the heat insulation layer and a composition for the second refractory layer are prepared. Next, the prepared composition for the heat insulation layer is applied to one surface (inner surface) of the heat-resistant nonwoven fabric as the first refractory layer 22. Subsequently, a polyester fiber nonwoven fabric as the cover layer 24 is disposed on the surface of the applied composition for the heat insulation layer. In this state, the composition for the heat insulation layer is dried to form the heat insulation layer 21. Then, the prepared composition for the second refractory layer is applied to the other surface (outer surface) of the heat-resistant nonwoven fabric and dried to form the second refractory layer 23.

[0022] <Other Forms> The refractory heat insulation sheet of the present disclosure is not limited to the above forms, and can be implemented in various modified forms and improved forms that can be performed by those skilled in the art.

[0023] [Configuration of Refractory Heat Insulation Sheet] The refractory heat insulation sheet of the present disclosure only needs to include a heat insulation layer, a first refractory layer, and a second refractory layer, and the other configurations are not particularly limited. The refractory heat insulation sheet is arranged such that the second refractory layer is on the outside, in other words, the heat insulation layer is on the side of the object to be protected. The thickness of the refractory heat insulation sheet may be appropriately determined according to the application, for example, it may be 10 mm or less, 8 mm or less, etc. Particularly from the viewpoints of thinning and enhancing flexibility, it is desirable to make the thickness 5 mm or less.

[0024] (1) Heat Insulation Layer The thickness of the heat insulation layer may be appropriately determined according to the application. From the viewpoint of heat insulation performance, it is desirable that the thickness of the heat insulation layer is 0.1 mm or more, 0.5 mm or more, or 1 mm or more. If the heat insulation layer is too thick, not only the cost will increase, but also the strength will decrease and it will become brittle. Therefore, it is desirable that the thickness of the heat insulation layer is 5 mm or less, 3 mm or less, or 2 mm or less.

[0025] The heat insulation layer has a porous structure. The porous structure is formed by a plurality of particles connected to form a framework with pores inside. The diameter of the particles (primary particles) forming the framework is preferably about 2 to 5 nm, and the size of the pores formed between the frameworks is preferably about 10 to 50 nm. Most of the pores are so-called mesopores with a size of 50 nm or less. Since the mesopores are smaller than the mean free path of air, the convection of air is restricted and the heat transfer is inhibited. The shape of the porous structure is not particularly limited, such as spherical or irregularly shaped lumps, but a chamfered shape or a spherical shape is desirable. In this case, since the dispersibility in the liquid is improved, it becomes easier to prepare a composition for the heat insulation layer (heat insulation layer composition). Also, the voids between the porous structures can be reduced and the filling amount can be increased, enhancing the heat insulation performance. The porous structure may be used in the as-manufactured state, or it may be further pulverized and used. For the pulverization treatment, a pulverization device such as a jet mill or a spheroidization treatment device may be used. By performing the pulverization treatment, the corners of the particles are removed and the particles become rounded. As a result, the surface of the heat insulation layer becomes smooth and cracks are less likely to occur. Also, when a binder is blended, since it becomes easier to be bonded by the binder, the porous structure is less likely to fall off.

[0026] The average particle diameter of the porous structure is preferably about 1 to 200 μm. The larger the particle diameter of the porous structure, the smaller the surface area and the larger the pore volume, so the effect of enhancing the heat insulation performance becomes greater. For example, those with an average particle diameter of 10 μm or more are suitable. On the other hand, considering the stability of the heat insulation layer composition and the ease of coating, those with an average particle diameter of 100 μm or less are suitable. Also, when using two or more kinds with different particle diameters in combination, since the porous structures with smaller diameters enter the gaps between the porous structures with larger diameters, the filling amount can be increased and the effect of enhancing the heat insulation performance becomes greater. The average particle diameter may be the median diameter (D 50 ) obtained from the volume-based particle size distribution measured by the laser diffraction / scattering method. For commercially available products, catalog values may be adopted.

[0027] The porous structure has a hydrophobic site at least on the surface among the surface and the interior. Having a hydrophobic site on the surface can suppress the penetration of moisture and the like, so that the pore structure is maintained and the heat insulation property is hardly impaired. For example, by performing surface treatment with a silane coupling agent or the like, functions such as hydrophobicity can be imparted to the surface of the porous structure. Further, in the manufacturing process of the porous structure, a hydrophobization treatment such as imparting a hydrophobic group may be performed.

[0028] The type of the porous structure is not particularly limited. Examples of the primary particles include silica, alumina, zirconia, titania, and the like. Among them, a silica aerogel in which the primary particles are silica, that is, a plurality of silica fine particles are connected to form a skeleton, is desirable because of its excellent chemical stability. The silica aerogel exhibits white color and reflects infrared rays. Therefore, when the silica aerogel is used, a heat shielding effect can be imparted to the heat insulating layer.

[0029] The method for manufacturing the silica aerogel is not particularly limited, and it may be one in which the drying process is performed at normal pressure or one in which the drying process is performed supercritically. For example, if the hydrophobization treatment is performed before the drying process, it is not necessary to dry supercritically, that is, it may be dried at normal pressure, so that it can be manufactured more easily and at lower cost. Depending on the difference in the drying method when manufacturing the aerogel, what is dried at normal pressure may be called "xerogel" and what is dried supercritically may be called "aerogel", but in this specification, both are collectively referred to as "aerogel".

[0030] The content of the porous structure in the heat insulation layer may be appropriately determined in consideration of heat insulation performance, mechanical strength, etc. For example, from the viewpoint of reducing the thermal conductivity (increasing the heat insulation performance), the content of the porous structure is desirably 40% by mass or more when the total mass of the heat insulation layer is 100% by mass. It is more preferable that it is 50% by mass or more, 60% by mass or more. On the other hand, when the amount of the porous structure increases, there is a risk that the porous structure is likely to fall off. Therefore, the content of the porous structure is desirably 75% by mass or less when the total mass of the heat insulation layer is 100% by mass. It is more preferable that it is 70% by mass or less.

[0031] The heat insulation layer may be formed by applying and drying a liquid (including slurry) heat insulation layer composition, or may be formed by pressing and molding a porous structure and powders of a binder described later. Further, the porous structure may be impregnated into a fiber base material such as polyester or glass fiber in a sol state which is a precursor thereof, and gelled and dried by heating or the like to form a sheet.

[0032] From the viewpoint of suppressing the fall-off of the porous structure, a binder may be blended in the heat insulation layer. As the binder, from the viewpoint of facilitating the preparation of the heat insulation layer composition, it is preferable to use a binder (aqueous binder) having water (including pure water, tap water, etc.) as a solvent. The component of the binder may be an organic material or an inorganic material. As an organic binder whose component is an organic material, there are a water-soluble binder and an emulsion binder, and among them, an emulsion binder (aqueous emulsion binder) is preferable. The aqueous emulsion binder is emulsified by the introduction of a surfactant or a hydrophilic group. According to the aqueous emulsion binder, since the hydrophilicity decreases due to the volatilization of the surfactant and the hydrophilic group during drying and it becomes difficult to dissolve in water, it is considered that stickiness is less likely to occur after the heat insulation layer composition is cured. As a method of emulsification, either a forced emulsification type using a surfactant as an emulsifier or a self-emulsification type into which a hydrophilic group is introduced may be used.

[0033] The organic material may be a resin or a rubber. From the viewpoint of high adhesiveness to the porous structure and making the heat insulation layer flexible and less likely to crack, the glass transition temperature (Tg) of the binder is desirably -5°C or lower, more desirably -20°C or lower. For example, in the case of an aqueous emulsion-based binder, it may be a resin emulsion or a rubber emulsion. Examples of the resin include acrylic resin, urethane resin, and a mixture of acrylic resin and urethane resin. Examples of the rubber include styrene-butadiene rubber (SBR), nitrile rubber, silicone rubber, urethane rubber, and acrylic rubber. From the viewpoint of making the heat insulation layer flexible, urethane resin, SBR, etc. are suitable. From the viewpoint of increasing the strength of the binder part and improving the strength of the heat insulation layer, a cross-linking agent or the like may be used in combination to cross-link the binder components.

[0034] From the viewpoint of reducing the decomposition and deterioration of the organic components in a high-temperature atmosphere and suppressing the occurrence of cracks and the like, it is desirable to use an inorganic binder in which the components of the binder are inorganic materials. Examples of the inorganic materials include metal oxides such as silica, titania, zinc oxide, and zirconia, as well as water glass (sodium silicate), cement, plaster, magnesium silicate, quicklime, and slaked lime. Among them, a binder containing silica is suitable because it is easily compatible with the porous structure and is inexpensive and easily available. In addition, a high-strength heat insulation layer can be formed by reacting with water as a solvent and filling the gaps between the porous structures to form a binder. Cement, plaster, and magnesium silicate, which are hydraulic materials, are also suitable because they are inexpensive and easily available.

[0035] When the inorganic material is nanoparticles (particles on the nanometer order), the disadvantages of hardness and brittleness due to the heat insulation layer having the inorganic material can be improved. As the binder having silica nanoparticles, colloidal silica using water as a dispersion medium, sodium silicate solution, etc. may be used. As the binder having titania nanoparticles, an aqueous dispersion of titania, etc. may be used.

[0036] In addition to the porous structure and the binder, the heat insulation layer may contain other components such as a crosslinking agent, a thickening agent, and reinforcing fibers. A porous structure having hydrophobic sites on its surface or inside is difficult to be wetted by water. Among them, silica aerogel has a small specific gravity and thus easily floats on water. Therefore, it is difficult to disperse silica aerogel in a binder solution using water as a solvent, and the dispersion process takes time. For example, when a thickening agent is added, the viscosity of the binder solution increases, the water suspension property of the hydrophobic porous structure is improved, and the porous structure is easily dispersed. Thereby, the time required for dispersing the porous structure can be shortened, and the productivity can be increased. Further, since flexibility is imparted to the heat insulation layer, the generation of cracks is also suppressed. As the thickening agent, in addition to CMC, polysaccharides such as polyethylene oxide (PEO), carboxyethyl cellulose, carboxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, xanthan gum, agarose, carrageenan, polyvinyl alcohol, glucomannan, etc. may be used.

[0037] When reinforcing fibers are added, they physically entangle around the porous structure, thereby improving the mechanical strength of the heat insulation layer and suppressing the detachment of the porous structure. The type of the reinforcing fibers is not particularly limited, but considering heat resistance and the like, glass fibers, ceramic fibers, etc. are suitable.

[0038] (2) The first refractory layer The first refractory layer is disposed on one side in the thickness direction of the heat insulating layer and is made of a heat-resistant fiber sheet. The fiber sheet preferably contains fibers with a softening point of 700 °C or higher from the viewpoint of enhancing heat resistance and suppressing the intrusion of flames into the heat insulating layer. Suitable fibers include glass fibers, ceramic fibers, and the like. The fiber sheet may further contain heat-resistant resin fibers such as polyimide and polyamide. In addition, as components other than fibers, inorganic particles, binders for binding fibers to each other, and the like may be included. Examples of the inorganic particles include talc, kaolinite, montmorillonite, mica, silica, potassium titanate, titanium oxide, silicon nitride, alumina, aluminum nitride, silicon carbide, zirconia, and the like. For example, a fiber sheet that satisfies the following condition (a) is suitable because it has a high flame blocking effect. (a) When a flame at 1000 °C is ejected by a propane gas burner and the fiber sheet is held in contact with the flame for 5 minutes, no holes are formed.

[0039] The thickness of the first refractory layer (fiber sheet) may be appropriately adjusted according to the flame blocking performance. For example, it may be 0.2 mm or more, 0.5 mm or more, or 1 mm or more. On the other hand, considering thinning, flexibility, etc., it may be 2 mm or less or 1.5 mm or less.

[0040] (3) The second refractory layer The second refractory layer is laminated on the first refractory layer and has one or more flame retardants selected from intumescent flame retardants and expanded graphite, and an organic binder. As the flame retardant, one or both of an intumescent flame retardant and expanded graphite are used as a chemical for forming an expanded non-combustible layer when heated, but other flame retardants may be added. When heated, the intumescent flame retardant decomposes to generate gas. This gas expands the carbonized layer formed from carbon generated from organic compounds such as the organic binder, and an expanded non-combustible layer is formed. Examples of the intumescent flame retardant include ammonium polyphosphate and melamine polyphosphate. From the viewpoint of improving water resistance and flame retardancy, those in which the surfaces of these particles are coated with a melamine resin or the like may be used. Expanded graphite is obtained by inserting a substance that generates gas upon heating between the layers of flaky graphite. When heated, expanded graphite expands due to the gas generated from the interlayer substance, thereby forming an expanded non-combustible layer.

[0041] From the viewpoint of enhancing the flame retardant effect, the content of the flame retardant is preferably 30% by mass or more, more preferably 40% by mass or more, based on 100% by mass of the total mass of the second refractory layer. On the other hand, since the function of suppressing the intrusion of flames is possessed not only by the second refractory layer but also by the first refractory layer, the desired fire resistance of the entire fireproof heat insulation sheet can be achieved even if the amount of the flame retardant in the second refractory layer is not so large. For example, the content of the flame retardant can be 80% by mass or less, and further 70% by mass or less.

[0042] The organic binder binds the flame retardants together and serves to supply carbon for forming an expanded non-combustible layer when an intumescent flame retardant is used. The type of the organic binder is not particularly limited, but it is desirable to have one or more selected from acrylic polymers, urethane polymers, and polyhydric alcohols because of their excellent binding properties and flexibility. One of these may be used alone, or two or more of them may be used in combination. Here, "polymer" is a concept including resins and rubbers.

[0043] The thickness of the second fire-resistant layer may be adjusted appropriately depending on the flame-blocking performance, and may be, for example, 0.5 mm or more or 1 mm or more. On the other hand, considering thinness and flexibility, it may be 2 mm or less or 1.5 mm or less. The second fire-resistant layer expands when heated, and the thickness after expansion can be adjusted by the content of the flame retardant, etc. For example, the thickness after heating (expansion) can be about 1.5 to 5 times the thickness before heating.

[0044] (4) Cover layer As shown in the second embodiment above, the fireproof and insulating sheet of the present disclosure may also include a cover layer disposed on the other side of the insulating layer in the thickness direction. The material and form of the cover layer are not particularly limited, and examples include woven fabric, nonwoven fabric, and films and sheets formed from resin, paper, etc. The cover layer may consist of a single layer or a laminate consisting of two or more layers of the same or different materials. Nonwoven fabric is preferred because of its light weight, flexibility, low cost, and high effectiveness in preventing the porous structure from falling off. Examples of fibers that can be used include synthetic fibers such as polyester, polypropylene, and polyamide, and inorganic fibers such as glass fiber, silica fiber, alumina fiber, ceramic fiber, and rock wool. The thickness of the cover layer can be determined appropriately depending on the application. For example, considering thinness and flexibility, a thickness of 1 mm or less or 0.5 mm or less is preferable, while considering reinforcement, a thickness of 0.1 mm or more or 0.3 mm or more is preferable.

[0045] (5) Other The fire-resistant heat insulating sheet of the present disclosure may include an adhesive layer between the layers to increase the adhesive strength between the layers. The adhesive layer may contain a flame retardant in addition to an adhesive component.

[0046] [Fireproof and heat-insulating sheet manufacturing method] As described in the first and second embodiments above, the refractory heat insulation sheet of the present disclosure can be manufactured by applying a composition for a heat insulation layer to one surface of a fiber sheet of a first refractory layer, drying it to form a heat insulation layer, applying a composition for a second refractory layer to the other surface of the fiber sheet, and drying it to form a second refractory layer. Further, in the form including a cover layer, as a manufacturing method different from the second embodiment, a composition for a heat insulation layer may be applied to one surface of the cover layer, a fiber sheet of a first refractory layer may be disposed thereon, and then dried to form a heat insulation layer. Then, a composition for a second refractory layer may be applied to the surface of the fiber sheet and dried to form a second refractory layer. For the application of the composition, brushing, or a coating machine such as a blade coater, a bar coater, a die coater, a comma coater (registered trademark), a roll coater, or a spray may be used. Drying may be performed at a temperature of 80 to 150°C for several minutes to several tens of minutes. Further, when the heat insulation layer is formed in a sheet shape, the fiber sheet of the first refractory layer and, if necessary, the cover layer may be laminated by adhering them to the heat insulation layer.

Examples

[0047] Next, the present disclosure will be described more specifically with reference to examples. In this example, a sample of the refractory heat insulation sheet of the present disclosure and a sample of a conventional refractory sheet were prepared, and the heat insulation properties of each were evaluated.

[0048] <Preparation of Samples> (1) Example 1 (a) Preparation of Composition for Heat Insulation Layer To water, a urethane resin emulsion (Permaline (registered trademark) UA-368 manufactured by Sanyo Chemical Industries, Ltd., solid content 50% by mass) and CMC (Cellogen (registered trademark) BSH-12 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added, and silica aerogel (average particle diameter 90 μm) was added while stirring with a stirring blade to prepare a composition for a heat insulation layer.

[0049] (b) Preparation of Composition for Second Refractory Layer To water, a urethane resin emulsion (the same as above) and ammonium polyphosphate powder (average particle diameter 10 μm) were added, and the mixture was stirred with a stirring blade to prepare a composition for a second refractory layer.

[0050] (c) Manufacture of refractory heat insulating sheet First, the prepared composition for the heat insulating layer was applied to the surface of a heat-resistant nonwoven fabric (Mitsubishi Paper Mills Ltd. "GP100-TRX", thickness 0.5 mm) using a blade coater. Next, a polyester fiber nonwoven fabric (thickness 0.3 mm) was placed on the surface of the applied composition for the heat insulating layer and held at 150°C for 10 minutes to dry the composition for the heat insulating layer. Subsequently, the composition for the second refractory layer was applied to the back surface of the heat-resistant nonwoven fabric using a blade coater and held at 150°C for 10 minutes to dry the composition for the second refractory layer. In this way, a refractory heat insulating sheet composed of "polyester fiber nonwoven fabric (cover layer) / heat insulating layer / heat-resistant nonwoven fabric (first refractory layer) / second refractory layer" was manufactured. The manufactured refractory heat insulating sheet was a square sheet with a length of 150 mm and a width of 150 mm, and the thickness was 2.8 mm. The content of silica aerogel in the heat insulating layer was 60% by mass, and the content of the flame retardant in the second refractory layer was 45% by mass (both based on 100% by mass of the total mass of the layer). The manufactured refractory heat insulating sheet was used as the sample of Example 1.

[0051] (2) Comparative Example 1 A refractory sheet "SK Taika Sheet (registered trademark)" (thickness 3.5 mm) manufactured by Esca Chemical Co., Ltd. was cut into a square shape of the same size as the sample of Example 1 and used as the sample of Comparative Example 1.

[0052] (3) Comparative Example 2 Two refractory sheets "Fiblock (registered trademark) TBCZ001" (thickness 2.25 mm) manufactured by Sekisui Chemical Co., Ltd. were cut into square shapes of the same size as the sample of Example 1, and a laminated sheet obtained by overlapping them in the same direction was used as the sample of Comparative Example 2.

[0053] [Evaluation of heat insulation property] [Experimental method] For each sample, a flame exposure experiment was conducted. In the flame exposure experiment, the flame of a propane gas burner was applied to the surface of the sample and held in that state for 15 minutes, and then the temperature of the back surface of the sample was measured. The higher the heat insulation property of the sheet, the lower the back surface temperature. The flame temperature of the burner was adjusted to 800 °C at a position 25 mm away from the surface of the sample. For the sample of Example 1, the flame was applied to the surface of the second refractory layer, and the temperature of the surface of the polyester fiber nonwoven fabric (the back surface of the sample) was measured.

[0054] [Experimental Results] Table 1 shows the types, thicknesses, and heat insulation evaluation results of the samples.

Table 1

[0055] As shown in Table 1, the back surface temperature of the sample of Example 1 was 182 °C, and there were no holes in the sample. In contrast, the back surface temperatures of the samples of Comparative Examples 1 and 2 both exceeded 200 °C. Thus, it was confirmed that the fireproof heat insulation sheet of the present disclosure is excellent in heat insulation property and has a high effect of suppressing the temperature rise of the object to be protected.

Industrial Applicability

[0056] The fireproof heat insulation sheet of the present disclosure can be applied to building materials such as steel frames and wall materials, fuel tanks mounted on vehicles, hydrogen tanks for fuel cell vehicles, battery casings for electric vehicles, and the like.

Explanation of Reference Numerals

[0057] 10, 20: Fireproof heat insulation sheet, 11, 21: Heat insulation layer, 12, 22: First refractory layer, 13, 23: Second refractory layer, 24: Cover layer.

Claims

1. A heat-insulating layer having a porous structure in which a plurality of particles are connected to form a skeleton, having pores inside, and having a hydrophobic site at least on the surface; A first refractory layer disposed on one surface in the thickness direction of the heat-insulating layer and made of a heat-resistant fiber sheet; A second refractory layer laminated on the first refractory layer and having a flame retardant containing an intumescent flame retardant and an organic binder; A refractory heat-insulating sheet characterized by comprising the above.

2. The refractory heat-insulating sheet according to Claim 1, wherein the fiber sheet has fibers with a softening point of 700 °C or higher.

3. The refractory heat-insulating sheet according to Claim 1 or 2, wherein the fiber sheet has one or more selected from glass fibers and ceramic fibers.

4. The refractory heat-insulating sheet according to any one of Claims 1 to 3, wherein the intumescent flame retardant is one or more selected from ammonium polyphosphate and melamine polyphosphate.

5. The refractory heat-insulating sheet according to any one of Claims 1 to 4, wherein the organic binder has one or more selected from acrylic polymers, urethane polymers, and polyhydric alcohols.

6. The refractory heat-insulating sheet according to any one of Claims 1 to 5, wherein the content of the flame retardant is 30% by mass or more and 80% by mass or less when the total mass of the second refractory layer is 100% by mass.

7. The refractory heat-insulating sheet according to any one of Claims 1 to 6, further comprising a cover layer disposed on the other surface in the thickness direction of the heat-insulating layer.

8. The refractory heat-insulating sheet according to Claim 7, wherein the cover layer is made of a non-woven fabric.

9. The refractory heat-insulating sheet according to any one of Claims 1 to 8, wherein the porous structure is a silica aerogel in which a plurality of silica fine particles are connected to form a skeleton.

10. The refractory heat-insulating sheet according to any one of Claims 1 to 9, wherein the overall thickness is 10 mm or less.

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