Laminated insulation and flame-resistant sheet

Abstract

This invention provides a heat-insulating and flame-retardant sheet and a method for manufacturing the same, which uses aerogel as an inorganic particle with excellent heat insulation properties, and solves the problems of powder shedding and surface powderiness. [Solution] A laminated heat-insulating and flame-shielding sheet is provided, in which a second inorganic fiber substrate is laminated on both sides of a heat-insulating layer in which heat-insulating particles are held within an entangled group of first inorganic fibers, wherein the heat-insulating particles are hydrophilic polymer-attached aerogel particles in which a hydrophilic polymer is attached to at least a portion of the surface of hydrophobic aerogel particles, and the heat-insulating layer and the second inorganic fiber substrate are joined by the hydrophilic polymer.

Description

[Technical Field]

[0001] The present invention relates to a laminated thermal insulation and flame-shielding sheet, which is a flexible, thin, sheet-like thermal insulation material utilizing aerogel, and which improves upon the shedding of aerogel particles and the powdery texture of the sheet surface. [Background technology]

[0002] As a lightweight, heat-insulating, and flame-resistant insulating material, an insulating material is known in which aerogel with excellent heat insulation properties is held in a matrix.

[0003] For example, the composite material disclosed in Japanese Patent No. 5851983 (Patent Document 1) is a composite material comprising "a) a hydrophobic aerogel component; b) a binder selected from the group consisting of cement, gypsum, lime, and any combination thereof; and c) a surfactant; wherein the composite material has a thermal conductivity of 30 mW / (m·K) or less as measured according to ASTM C518." The thermal insulation materials disclosed herein utilize hardened materials such as cement as a matrix, making it difficult to wrap around or bend them to insulate a structure. A flexible, sheet-like thermal insulation material is desired as a general-purpose thermal insulation material.

[0004] As an example of a flexible sheet-like heat insulating material, Japanese Patent Publication No. 2015-163815 (Patent Document 2) describes a material in which, per 100 parts by weight of main fibers, hydrophobic aerogel particles having a high heat insulating effect are used (the aerogel particles used in the example have an average particle size of 5 μm and a specific surface area of ​​750 m²). 2 We propose an insulating material (insulating sheet) that contains 35 to 210 parts by weight of a water-soluble polymer selected from the group consisting of cationic polymers and amphoteric polymers, and / or a binder containing low-melting-point synthetic fibers. Examples of main fibers include synthetic fibers such as polyester fibers and aramid fibers, as well as inorganic fibers such as ceramic fibers, alumina fibers, and glass fibers (

[0018] ). However, in the examples, only sheets made using organic fibers such as pulp, polyester fibers, and vinylon binder fibers have been produced. Regarding the binder, it has been explained that because methyl silicate particles exhibit anionic or amphoteric properties, using a cationic polymer and / or amphoteric polymer as a binder can promote the aggregation of pulp and porous silica particles, thereby increasing the yield (

[0026] ). In a specific example, a thermal insulation sheet is produced by papermaking using a slurry prepared by adding main fibers (organic fibers such as pulp, polyester fibers, and vinylon binder fibers), aerogel, and a water-soluble polymer to water, and stirring the mixture.

[0005] Furthermore, Japanese Patent No. 7364742 (Patent Document 3) proposes a heat transfer suppression sheet having inorganic particles with heat insulating properties such as silica aerogel and organic fibers having a so-called core-sheath structure. Here, it is explained that by using organic fibers in which the sheath portion has a lower melting point than the core portion, the surface layer of the organic fibers becomes a welded portion, and the heat insulating particles are welded to the organic fibers (Claim 1,

[0015] ).

[0006] On the other hand, as a sandwich-type composite thermal insulation material in which a thermal insulation layer made of a mixture of aerogel and reinforcing fibers is sandwiched, US2019 / 0249816 (Patent Document 4) discloses a laminated thermal insulation material in which a thermal insulation layer made of a glass fiber needle mat impregnated with aerogel is used as an intermediate layer and sandwiched between two substrates such as glass cloth. In this case, the thermal insulation layer is binderless (

[0084] ), but the glass cloth and the thermal insulation layer are joined via an adhesive layer (

[0078] , Figure 1).

[0007] Furthermore, a laminated insulation material has been proposed in which an insulating paint containing aerogel and an emulsion-type binder is applied to a substrate to create a layered insulating layer. For example, Japanese Patent No. 7223600 (Patent Document 5) proposes a laminated thermal insulation material (first thermal insulation layer / second thermal insulation layer / heat reflective layer) obtained by applying a thermal insulation coating containing silica aerogel and an emulsion-type aqueous binder (e.g., urethane resin) to a nonwoven fabric or foam that will serve as the first thermal insulation layer, laminating a heat reflective layer (aluminum vapor-deposited film) to the coating film, and then curing the coating film. In this example, the second thermal insulation layer and the heat reflective layer are bonded together by the aqueous binder. In the example, a thermal insulation coating containing 14% by mass of urethane resin emulsion and 0.32% by mass of carboxymethylcellulose is used with respect to hydrophobic aerogel (average particle size 90 μm). For laminated thermal insulation materials with a silica aerogel content of 95-85 volume% and an aqueous binder content of 4.2-14.6 volume%, the interlayer adhesion between the heat reflective layer and the second thermal insulation layer has been evaluated, and it has been noted that peeling was observed when the aqueous binder content was 6.6 volume% or less.

[0008] Furthermore, in the thermal insulation material disclosed in Japanese Patent Application Publication No. 2021-143733 (Patent Document 6), in which a thermal insulation layer is laminated on a substrate such as glass cloth, the thermal insulation layer is a film formed by applying and curing a paint to the substrate. Such a coating film is a cured film of thermal insulation paint in which silica aerogel (a porous structure), reinforcing fibers, and metal oxide nanoparticles (such as colloidal silica) as a binder are dispersed in a dispersion medium such as water. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 5851983 [Patent Document 2] Japanese Patent Publication No. 2015-163815 [Patent Document 3] Patent No. 7364742 [Patent Document 4] US2019 / 0249816 issue [Patent Document 5] Patent No. 7223600 [Patent Document 6] Japanese Patent Publication No. 2021-143733

Summary of the Invention

Problems to be Solved by the Invention

[0010] The heat insulation sheet combining fibers and inorganic particles as proposed in Patent Documents 2 and 3 is thin and flexible. On the other hand, in the case of a sheet combining fibers and inorganic particles, it is known that there are problems such as the inorganic particles falling off (powdering) or the sheet surface being powdery. Such problems need to be improved in relation to the attachment to the heat insulation object and the handling property during construction.

[0011] In Patent Document 2, in order to suppress powdering, it is proposed to coat the surface of the heat transfer suppression sheet with a polymer film (〔0099〕). Regarding the polymer film, various polymer films such as low melting point thermoplastic films such as PET, polyethylene, and polypropylene, thermosetting type films such as polyimide and polyamideimide, and fluororesin-based films such as PTFE are exemplified. Regarding the coating method, there is an explanation to some extent such as "a method of sticking with an adhesive or the like, a method of wrapping the heat transfer suppression sheet with a film, a method of accommodating the heat transfer suppression sheet in a bag-shaped film, etc.".

[0012] By coating the surface with a polymer film, the handling property caused by the powdery surface can be improved. On the other hand, from the viewpoint of heat resistance, the polymer film has a problem that it melts in a high temperature range where heat insulation is required and further burns when exposed to a flame.

[0013] The heat insulation layer contained in the laminated heat insulation material proposed in Patent Documents 5 and 6 is in a state where aerogel particles are dispersed mainly in a binder corresponding to the vehicle of the paint, so it is stably held compared to the case of being held by fibers. However, since the heat insulation layer corresponding to the coating film exists in a layered form of the vehicle, a sufficient heat insulation effect may not be obtained depending on the content ratio and volume ratio of the vehicle and the aerogel particles. In addition, heat-insulating paints using organic vehicles may be restricted in their use as flame-shielding sheets.

[0014] In the composite heat-insulating material proposed in Patent Document 4, in the aerogel, the outer surface of the heat-insulating layer in which the aerogel is impregnated and dispersed without a binder in a fiber mass such as a needle mat is covered with an inorganic fiber-based substrate such as a glass cloth. And since an organic binder such as polyamide is used for joining the heat-insulating layer and the inorganic fiber-based substrate, it disappears by combustion at high temperatures and it becomes difficult to secure the joining force. As a matrix for holding the aerogel, since a mass of fiber groups such as a needle mat is used, it tends to be thicker than the heat-insulating layer formed by a papermaking method or the like. When constructing a structure by pasting, laminating, winding, etc., a thick sheet is disadvantageous in terms of handling properties.

[0015] As the aerogel used as a heat-insulating material, usually, a hydrophobic aerogel is used. In a heat-insulating layer or a heat-insulating sheet produced from an aqueous dispersion or a slurry containing an aerogel for a sheet-like heat-insulating material, by using a hydrophobic aerogel as a heat-insulating imparting particle, it is possible to prevent the penetration and intrusion of water into the pores, and it becomes possible to maintain the original high porosity. On the other hand, in order to obtain a heat-insulating layer or a heat-insulating sheet in which the aerogel is uniformly dispersed, it is necessary to stably disperse the hydrophobic aerogel in the state of a dispersion liquid. In Japanese Patent Application Laid-Open No. 2018-43927, it is explained that by coexisting a nonionic surfactant having a specific structure and nanofibers having an anionic functional group, an aggregate (micelle) of silica aerogel particles is formed and the state of the micelle can be stably maintained. However, the surface properties and powder falling of the solid composite material (heat-insulating material or sound-absorbing material) obtained by drying the aqueous dispersion have not been evaluated.

[0016] The present invention has been made in view of the above circumstances, and an object thereof is to provide a flexible heat-insulating sheet using a hydrophobic aerogel as an inorganic particle excellent in heat-insulating properties, which solves the problems of powder falling and a powdery surface, and has excellent handling properties. A laminated heat-insulating and flame-shielding sheet. [Means for solving the problem]

[0017] The inventors, with the aim of providing a thin, sheet-like thermal insulation material, created a paper-like thermal insulation layer and solved the problem of powder shedding by laminating an inorganic fiber substrate on the surface of the thermal insulation layer. They then investigated various methods for joining the thermal insulation layer and the inorganic fiber substrate without interposing an adhesive layer, and completed the present invention.

[0018] In other words, the laminated heat-insulating and flame-resistant sheet of the present invention is a heat-insulating and flame-resistant sheet having the following characteristics. [1] A laminated thermal insulation and flame-shielding sheet in which a second inorganic fiber substrate is laminated on both sides of a thermal insulation layer in which thermal insulation particles are held within a first group of entangled inorganic fibers, The aforementioned heat-insulating particles are hydrophilic polymer-attached aerogel particles, in which a hydrophilic polymer is attached to at least a portion of the surface of the hydrophobic aerogel particles. A laminated heat-insulating and flame-shielding sheet in which the heat-insulating layer and the coating layer are joined by the hydrophilic polymer.

[0019] [2] The laminated heat insulating and flame-shielding sheet according to embodiment [1], wherein the first inorganic fiber is at least one selected from the group consisting of silica fiber, silica-alumina fiber, alumina fiber, mullite fiber, zirconia fiber, silicon carbide fiber, biosoluble fiber (AES), refractory ceramic fiber (RCF), ceramic fiber, glass fiber, rock wool, carbon fiber, and graphite fiber.

[0020] [3] The laminated heat-insulating and flame-shielding sheet according to embodiment [1] or [2], wherein the fiber length of the first inorganic fiber is 3.0 mm to 15 mm. [4] The laminated heat-insulating and flame-shielding sheet according to any one of embodiments [1] to [3], wherein the inorganic fiber base material is a glass fiber woven fabric, a nonwoven fabric, or paper. [5] The laminated heat insulating and flame-shielding sheet according to any one of embodiments [1] to [4], wherein the hydrophobic aerogel particles are silica aerogel with a pore size of 20 nm or less and a porosity of 80% or more.

[0021] [6] The laminated heat-insulating and flame-shielding sheet according to any one of embodiments [1] to [5], wherein the hydrophilic polymer is polyvinyl alcohol. [7] A laminated heat insulating and flame-shielding sheet according to any one of embodiments [1] to [6], wherein the weight ratio of the hydrophilic polymer to the aerogel particles (hydrophilic polymer / aerogel particles) is 1 / 1 to 1 / 30. [8] The laminated heat-insulating and flame-resistant sheet according to any one of embodiments [1] to [7], wherein the heat-insulating layer is paper made by wet papermaking of a suspension containing the first inorganic fibers and the hydrophilic polymer-adhered aerogel particles. The laminated heat-insulating and flame-resistant sheet according to claim 1.

[0022] The present invention also includes the method for manufacturing the laminated heat-insulating and flame-shielding sheet described above. The manufacturing method of the present invention is a method for manufacturing a laminated heat-insulating and flame-shielding sheet described in any one of the above embodiments [1] to [7], A process of papermaking a sheet with a water content of 70-85% by mixing an aqueous slurry containing a hydrophobic aerogel and a hydrophilic polymer with a first fiber dispersion liquid in which first inorganic fibers are dispersed in an aqueous medium; A manufacturing method comprising the step of drying the obtained insulation layer sheet by heating and pressurizing it while sandwiching both sides between a second inorganic fiber substrate.

[0023] Another manufacturing method is a method for manufacturing a laminated heat-insulating and flame-shielding sheet described in any one of the above embodiments [1] to [7], A step of preparing an aqueous suspension in which the pulverized aerogel material is dispersed among the first inorganic fibers by adding a lump of hydrophilic polymer-attached aerogel to a first fiber dispersion liquid in which first inorganic fibers are dispersed in an aqueous medium, and then stirring to pulverize the lump; A step of papermaking the aqueous suspension to obtain a sheet with a moisture content of 70-85%; A manufacturing method comprising the step of drying the obtained sheet by heating and pressurizing it while sandwiching both sides of the sheet between a second inorganic fiber substrate. [Effects of the Invention]

[0024] The laminated heat-insulating and flame-shielding sheet of the present invention has an intermediate layer containing an insulating layer that contains aerogel, which causes powder shedding and powderiness, and covers both sides with an inorganic fiber substrate. This avoids the problems of powder shedding and surface powderiness caused by aerogel, and allows for the exhaust of gases generated from the insulating layer. Furthermore, since hydrophilic polymer-attached aerogel is used as the heat-insulating particle, even when the heat-insulating layer is created using a papermaking method that utilizes an aqueous medium, hydrophobic aerogel particles can be dispersed and distributed within the first group of inorganic fibers that form the matrix of the heat-insulating layer. Furthermore, the hydrophilic polymer adhering to the surface of the hydrophobic aerogel can also function as a binder between the heat insulating layer and the inorganic fiber substrate. Therefore, in the manufacturing process of the laminated heat insulating and flame-retardant sheet, a separate coating process for binders, etc., is unnecessary, simplifying the manufacturing process and reducing the content of organic components that cause a decrease in flame-retardant properties. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic diagram showing the configuration of one embodiment of the laminated heat-insulating and flame-shielding sheet of the present invention. [Figure 2] This is a schematic diagram illustrating the interface structure between the thermal insulation layer and the inorganic fiber substrate that forms the coating layer of the laminated thermal insulation and flame-shielding sheet of the present invention. [Figure 3] This is a diagram illustrating the thermal insulation test performed in the example. [Figure 4] This is a micrograph (magnification 500x) of the surface of the laminated heat-insulating and flame-retardant sheet No. 1, which was fabricated in the example. [Figure 5] This is a diagram illustrating the bonding strength measurement method used in the example. [Modes for carrying out the invention]

[0026] Figure 1 is a schematic diagram showing the configuration of one embodiment of the laminated heat-insulating and flame-shielding sheet of the present invention. The heat-insulating and flame-resistant sheet of this embodiment is a laminated sheet in which an inorganic fiber base material B is laminated on both sides of a heat-insulating layer A.

[0027] As shown in Figures 1 and 2, the thermal insulation layer A contains a first inorganic fiber 1 and a hydrophobic aerogel 2 to which hydrophilic polymers 3 are attached as thermal insulation particles. The thermal insulation layer A may also contain fibers other than the first inorganic fiber 1 that form the matrix (such as organic fibers) 4. Furthermore, the heat insulating layer A and the inorganic fiber substrate (coating layer) B are joined together via the hydrophilic polymer 3. The thermal insulation layer A is synthesized by wet molding an aqueous suspension containing inorganic fibers 1 and hydrophilic polymer 3 attached to a hydrophobic aerogel 2, and the thermal insulation layer A and the inorganic fiber substrate B are bonded together by heating and pressurizing. The following provides a detailed explanation of each layer.

[0028] <Insulation layer (sheet-type insulation material) A> [Components] (1) Inorganic fiber (first inorganic fiber) The inorganic fibers forming the matrix of the heat insulating layer (first inorganic fibers) are not particularly limited, but are preferably inorganic fibers having a softening point or melting point of 700°C or higher. Specifically, silica fibers with 95% or more silica by weight, silica-alumina fibers, silicon carbide fibers, alumina fibers, mullite fibers, zirconia fibers, biosoluble fibers (AES), refractory ceramic fibers (RCF), silica-high content glass fibers known as T-glass fibers, rock wool, carbon fibers, graphite fibers, or combinations of two or more of these can be used, and can be appropriately selected depending on the application. Preferably, silica fibers, silica-alumina fibers, biosoluble fibers (AES), refractory ceramic fibers, and silica-high content glass fibers are used, and these may be used individually or in combination of two or more.

[0029] As the first inorganic fiber, it is preferable to use staple fibers with a diameter of 3 to 13 μm, preferably about 7 to 10 μm, and a length of 1 to 50 mm, preferably 3 to 30 mm. If the length is too short, the holding power of the heat-insulating particles tends to be insufficient.

[0030] The inorganic fiber content in the insulating layer A is 25% by weight or more, 30% by weight or more, 40% by weight or more, 70% by weight or less, 65% by weight or less, and 50% by weight or less. Within these ranges, it is appropriately selected depending on the type and content of the insulating inorganic particles and other components.

[0031] (2) Hydrophobic aerogel Hydrophobic aerogels are used as inorganic particles that impart thermal insulation. Aerogels are amorphous particles that have a porous structure in which multiple nanoparticles are linked together to form a framework (forming a three-dimensional network), resulting in pores between the particles. The pores described above are less than 1 micron (μm), preferably 50 nm or less, and more preferably about 20 nanometers (nm) or less. In such porous structures, the pores are nano-sized pores that form long, winding air channels that inhibit thermal and electrical conductivity. Air is trapped within these nano-sized pores, resulting in excellent thermal insulation.

[0032] The porosity is 80% or more, 90% or more, preferably more than 95%, resulting in a porous structure. Furthermore, the surface area of ​​the porous particles is approximately 300 m². 2 / g ~ approx. 1,000m 2 / g, preferably 500m 2 / g ~ approx. 1,000m 2 / g, BET surface area is 700m 2 / g~800m 2 It is / g.

[0033] Aerogels having the above-described structure can include silica aerogel and alumina aerogel, with silica aerogel being preferred among them. Such porous silica aerogels are manufactured by methods such as the sol-gel method, dry method (fumed silica), and wet method (precipitated silica), and the resulting particle size and aggregation state differ depending on the manufacturing method and conditions.

[0034] By end-capping the silanol groups present on the surface of aerogel particles produced by the sol-gel method using hydrophobic groups such as silylation agents, aerogel particles with a hydrophobic surface can be obtained.

[0035] A hydrophobic aerogel means that the surface of the aerogel particles is hydrophobic or water-repellent, specifically meaning that the wetting angle to water is 100 degrees or more, 110 degrees or more, 130 degrees or more, or 150 degrees or more. Due to this hydrophobicity, a high porosity can be maintained even when creating an insulating layer using the wet method described later. Hydrophobicity can be measured, for example, by contact angle measurement or methanol wettability.

[0036] The size of the aerogel particles, which are a group of nanoparticles, is not particularly limited, but within the insulating layer, they exist at a size of 150 μm or less, preferably 100 μm or less, and more preferably 50 μm or less. A commercially available aerogel having such a particle size may be used, or a larger aerogel may be crushed and then sieved to separate and remove the larger aerogel particles.

[0037] (3) Hydrophilic polymer The hydrophobic aerogel, acting as a heat insulating particle, exists in the heat insulating layer as a hydrophilic polymer-attached aerogel, in which a hydrophilic polymer is attached to or coated on its surface.

[0038] In the papermaking method described later, hydrophobic aerogels are usually difficult to disperse uniformly within the fiber cluster due to the difference in specific gravity between them and the fibers. In this regard, Patent Documents 1 and 2, among others, describe how the dispersibility of hydrophobic aerogels is enhanced by the coexistence of surfactants. However, surfactants cause excessive foaming during the preparation of the papermaking suspension, which places a heavy burden on the papermaking machine. Furthermore, foaming can lead to a decrease in the texture of the resulting sheet. In the present invention, by dispersing hydrophobic aerogels in a state where a hydrophilic polymer is attached to or coated on their surface (a state of hydrophilic polymer-attached aerogel), it becomes possible to disperse aerogels in an aqueous medium even in the absence of surfactants. This avoids the problem of foaming during the preparation of the papermaking suspension and further improves the texture of the sheet caused by foaming.

[0039] Examples of hydrophilic polymers that can be used include polysaccharides such as cellulose nanofibers, starch, amylose, cationized starch, and carboxymethylcellulose; and vinyl-based hydrophilic polymers such as polyvinyl alcohol, polyvinyl acetate, ethylene-vinyl alcohol resins, polyacrylic acid, sodium polyacrylate, and polyacrylamide. Of these, water-soluble polymers are preferred, water-soluble polymers having multiple primary or secondary hydroxyl groups are preferred, and polyvinyl alcohol is more preferred. These hydrophilic polymers are used as aqueous solutions or aqueous slurries in the adhesion treatment process described later, so they can be used in various forms such as powder, fibrous, granular, or high-viscosity fluid.

[0040] The molecular size (chain length) of these hydrophilic polymers tends to be larger than the pore size of the aerogel, and their molecular structure suggests that they surround the surface of the aerogel particles so that the hydrophilic groups face the dispersion medium. This makes it possible to increase the affinity of the hydrophobic aerogel surface state to the dispersion medium.

[0041] Hydrophilic polymers that yield highly viscous aqueous solutions are preferred, specifically hydrophilic polymers that yield aqueous solutions with a viscosity of 1 to 100 mPa·s at 4% concentration at 20 to 40°C are preferred.

[0042] In the case of saponified products such as polyvinyl alcohol, a degree of saponification of 75 to 100 mol%, preferably 77 to 99.9 mol%, and preferably 85 to 99 mol%, is preferable from the viewpoint of water solubility. In addition to unmodified polyvinyl alcohol, modified polyvinyl alcohol having multiple alcoholic hydroxyl groups in its side chains, or modified polyvinyl alcohol in which oxyalkylene groups or sulfonic acid groups have been introduced into its side chains, are also acceptable, as long as their water solubility and hydrophilicity are not impaired. When polyvinyl alcohol is used as the hydrophilic polymer, the degree of polymerization is 200 to 4000, preferably 200 to 3000, preferably 300 to 2800, and more preferably 400 to 2000. If the degree of polymerization is too low, the aerogel particles may not be adequately coated, or the polymer may penetrate some of the pores, impairing the thermal insulation properties of the hydrophobic aerogel particles. On the other hand, if the degree of polymerization is too high, the viscosity of the aqueous solution increases, and the dispersion workability of the aerogel particles during the adhesion treatment tends to decrease.

[0043] (4) Hydrophilic polymer-adhered aerogel When creating insulating layer sheets using a wet papermaking method with water as the dispersion medium, hydrophobic aerogels tend to separate easily from the aqueous phase. However, by attaching or coating the surface of porous particles with a hydrophilic polymer, they can be dispersed in the aqueous medium at the desired particle size, enabling distribution within the fiber group in the papermaking suspension (a mixture of fibers and aerogel).

[0044] The state of attachment is not particularly limited. It is sufficient for the particles to be attached to an extent that they can be stably dispersed in an aqueous medium. This can involve covering the entire surface of the aerogel particles, or it may simply involve partial covering or attachment.

[0045] (4-1) Hydrophilic polymer adhesion treatment Methods for attaching the aerogel to a surface include, for example, a) adding hydrophobic aerogel while stirring a (warm) aqueous solution of a hydrophilic polymer, and b) spraying the aqueous solution of the hydrophilic polymer onto the surface of the aerogel particles. Depending on the type of hydrophilic polymer, the aqueous solution may be heated as needed during preparation.

[0046] When using an aqueous solution of a hydrophilic polymer, the concentration of the solution is preferably 0.1 to 10% by weight, and particularly preferably 1 to 5% by weight. If the concentration is too low, the adhesion treatment tends to be insufficient. If it is too high, the aqueous solution will gel, making it difficult to mix and disperse the aerogel particles, and thus reducing handlingability.

[0047] The hydrophilic polymer-attached aerogel particles can be used in the form of an aerogel slurry obtained by the attachment treatment described in a) above, or in the form of a dried (lumpy) aerogel slurry. The dried aqueous slurry containing hydrophilic polymer-attached aerogel is usually obtained as a lump. The obtained lump may be crushed as appropriate and then sieved to produce a powder of the desired particle size, or it may be used as is in the preparation of the papermaking suspension. The lump of hydrophilic polymer-attached aerogel can be crushed and dispersed in the papermaking suspension preparation by a stirring and mixing step with the fiber dispersion liquid described later. Depending on the stirring conditions, the aerogel can be dispersed in the fiber dispersion in the form of aggregates with an average particle size of 5 to 200 μm, preferably 5 to 150 μm, and more preferably 10 to 100 μm.

[0048] (4-2) Content ratio of aerogel and hydrophilic polymer The amount of hydrophilic polymer needed is sufficient for the hydrophobic aerogel particles to be stably dispersed in water. Typically, the hydrophilic polymer / hydrophobic aerogel particle (weight ratio) is around 1 / 1 to 1 / 50, 1 / 2 to 1 / 10, or 1 / 3 to 1 / 8. If the proportion of hydrophilic polymer is too low, the amount adhering to the aerogel particles will be insufficient, reducing the dispersibility in water as an insulating particle, and also making it difficult to obtain sufficient bonding strength with the coating layer as a laminated insulating / flame-shielding sheet.

[0049] (4-3) Content of hydrophilic polymer-adhered aerogel particles The content of hydrophilic polymer-adhered aerogel particles in the insulating layer is 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 50% by weight or more, and 80% by weight or less, 70% by weight or less, and 60% by weight or less. Depending on the type of inorganic fiber used, the occupancy rate of aerogel particles in the insulating layer can be 50% by volume or more, 60% by volume or more, 70% by volume or more, and up to approximately 80% by volume.

[0050] (5) Organic fibers When creating an insulating layer by wet papermaking, in addition to the matrix inorganic fibers (first inorganic fibers), organic fibers, preferably thermoplastic fibers, may also be included. These organic fibers can impart flexibility and strength to the insulating layer. Furthermore, if the temperature during the drying process of the insulating layer web after papermaking and the bonding process with the covering substrate is set to a temperature above the softening temperature of the thermoplastic resin, the organic fibers can also act as a binder. They can soften and melt with heat, binding the fibers together, thereby suppressing the springback of the matrix inorganic fibers and making it easier to control the thickness of the resulting sheet.

[0051] Examples of organic fibers include pulp fibers, polyester fibers, polypropylene fibers, polyethylene fibers, acrylic fibers, polyvinyl chloride fibers, vinylidene fibers, nylon fibers, vinylon fibers, polyurethane fibers, rayon fibers, aramid fibers, and polyvinyl alcohol-based fibers. Alternatively, thermoplastic resin fibers with a core-sheath structure using fibers with a low softening temperature in the surface layer may also be used.

[0052] When thermoplastic resin fibers are used as organic fibers, staple fibers with a fiber diameter of 3 μm to 50 μm, preferably 5 μm to 30 μm, and a fiber length of 1 to 20 mm, preferably 3 to 10 mm, are preferably used. Since the thermoplastic resin fibers need to intertwine uniformly with the inorganic fibers that form the main body of the heat-insulating and flame-shielding sheet, it is preferable that they have a length similar to that of the inorganic fibers.

[0053] (6) Other ingredients (6-1) Other fibers In addition to the matrix inorganic fibers (first inorganic fibers) and organic fibers, the material may also contain other inorganic fibers such as glass fibers and mineral fibers, as needed.

[0054] Glass fibers can impart tensile strength to the insulation layer. The glass fibers used here may have less heat resistance than the glass fibers used as the first inorganic fiber in the insulation layer. E-glass fibers are a suitable choice due to their availability and cost-effectiveness.

[0055] The glass fibers should have a diameter of 1 to 10 μm, preferably 3 to 9 μm, and more preferably 4 to 6 μm. The fiber length should be long and strong enough to intertwine with the inorganic fibers that make up the heat insulating layer and the organic fibers used as a binder. Therefore, it is preferable to use staple fibers with a fiber length of 1 to 15 mm, preferably 2 to 10 mm, as the glass fibers.

[0056] Mineral fibers are minerals that have fibrous structures such as resinous, needle-like, columnar, or rod-like forms, and examples include potassium titanate whiskers and wollastonite. These mineral fibers have fiber lengths of 5 μm or more, 10 μm or more, 20 μm or more, and at most 1 mm or less, 500 μm or less, 200 μm or less, 100 μm or less, 80 μm or less, and 70 μm or less.

[0057] (6-2) Binder In the laminated heat-insulating and flame-retardant sheet of the present invention, since both sides of the heat-insulating layer A are sandwiched between inorganic fiber sheets B, it is possible to suppress the shedding of heat-insulating particles from the heat-insulating layer A, also known as powder shedding. However, from the viewpoint of yield in the manufacturing process of the heat-insulating layer A, and further from the viewpoint of increasing the bonding strength between the heat-insulating layer A and the inorganic fiber base material B, a binder may be included to the extent that it does not affect the heat insulation, flame-retardant properties, and flexibility.

[0058] As used herein, the term "binder" includes not only compounds that bind fibers together or fibers together with inorganic particles, but also coagulants conventionally used in papermaking methods (wet dewatering molding). A coagulant is a substance that promotes the aggregation of fibers and particles contained in a papermaking suspension by forming crosslinks, thereby improving yield.

[0059] (6-2a) Organic binder Organic binders can be used in various forms, such as powders, granules, colloidal solutions, and high-viscosity fluids. Examples include latex such as acrylic latex and (meth)acrylic latex; powdery thickening agents such as polyvinyl alcohol powder and starch; copolymers of styrene and butadiene, vinylpyridine, acrylonitrile, copolymers of acrylonitrile and styrene, etc.

[0060] These organic binders can provide strength to the wet sheet during papermaking. After papermaking and removal of the dispersion medium, even if the sheet solidifies, it can be softened again by heating, which is advantageous when forming it into a desired shape, such as slit or bend.

[0061] Furthermore, polymer flocculants such as polyacrylamide, acrylamide-sodium acrylate copolymer, and sodium polyacrylate may also be included as a type of organic binder. In the wet papermaking process, in the dewatering step using a mesh, particles smaller than the mesh opening pass through the mesh and cannot be filtered. In this case, it is preferable to add a polymer flocculant to the papermaking suspension to form flocculated flocs of a size that can be filtered and molded. In relation to this role, it is preferable that the organic binder corresponding to the flocculant is added after the preparation of a fiber dispersion liquid in which fibers and particles are homogeneously mixed, and further after the fiber dispersion liquid is mixed with a hydrophilic polymer-adhered aerogel (slurry).

[0062] The organic binder should be included in an amount sufficient to provide flexibility during post-processing or heat treatment of sheets obtained by the papermaking method, or to mitigate the expansion and contraction of the sheets during normal use when the temperature rises. Too much binder can lead to a decrease in heat resistance. Furthermore, at high temperatures exceeding those of normal use (up to about 200°C), the organic components may generate heat or decomposition gases due to oxidation. Therefore, the amount of organic binder (solid content concentration) in the papermaking suspension should be 1% by weight or more, 3% by weight or more, 5% by weight or more, 10% by weight or less, and 8% by weight or less.

[0063] (6-2b) Inorganic binder As inorganic binders, colloidal oxides such as colloidal silica, alumina sol, and titania sol; water glass, calcium silicate; hydrated magnesium silicate; and aluminum sulfate, which is classified as a fixing agent or inorganic flocculant, can be used.

[0064] Of these, colloidal silica can act as a binder by entering the space between the main inorganic fibers, the interfiber gaps, and the spaces between hydrophilic polymer-attached aerogel particles and fibers.

[0065] Aluminum sulfate improves water drainage and yield of fiber bundles, and is typically added as a fixative or yield enhancer in papermaking processes.

[0066] The inorganic binder content in papermaking suspensions is typically 1% by weight or more, 3% by weight or more, 10% by weight or less, 7% by weight or less, or 5% by weight or less.

[0067] (6-3) Other heat-insulating particles The laminated heat-insulating and flame-shielding sheet of the present invention may contain, in addition to the hydrophilic polymer-adhered aerogel, inorganic particles that can impart other heat-insulating properties. Other heat-insulating particles include, for example, aerogels that exhibit heat insulation based on high porosity and are not surface hydrophobic, porous or hollow inorganic particles such as glass bubbles and glass balloons; nanoparticles that can function like porous particles by forming aggregates (aglomerates) of nanoparticles; and ceramic particles that can scatter radiant heat, such as titanium dioxide, alumina, silicon carbide, and silica without binder function (crystalline silica powder, amorphous silica, fumed silica, etc.). It is preferable to include ceramic particles that can exhibit an insulating mechanism different from that of air, or ceramic particles that can exert an insulating mechanism in high-temperature ranges.

[0068] (6-4) Other fillers In addition to the above components, the papermaking suspension may also contain the following fillers in an amount of less than 10% by weight, preferably less than 5% by weight, and more preferably 3% by weight or less, relative to the total solid content.

[0069] Other fillers may include clay minerals such as the above-mentioned clay-like layered silica. Specifically, hydrated ferrosilicate minerals such as sepiolite, mica, kaolinite, smectite, montmorillonite, sericite, illite, gluconite, chlorite, talc, or mixtures thereof can be used. Of these, sepiolite, smectite, montmorillonite, bentonite, and mixtures thereof are preferred. These clay-like minerals, due to their excellent plasticity and flexibility, can penetrate into the gaps between fibers, dry and solidify, and function as a binder between fibers, thus possessing coating film-forming capabilities.

[0070] The layered silicate described above exists as a powder with an average particle size of 300 μm or less, preferably 200 μm or less, and more preferably 10 to 100 μm, in terms of equivalent circle diameter, before the preparation of the papermaking suspension. However, upon mixing with water, it becomes viscous, adhesive, and plastic, and has the ability to form a self-coating film. Therefore, after papermaking and drying of the papermaking suspension, the clay can solidify and set, containing inorganic particles (inorganic binder, heat-insulating particles) in the interfiber gaps.

[0071] Other solid fillers include, for example, neutralizing agents, lubricants, anti-blocking agents, flow improvers, release agents, flame retardants, colorants, wetting agents, viscous agents, yield improvers, paper strength improvers, water filter agents, pH adjusters, and the like.

[0072] [Preparation of the insulation layer (insulation sheet)] (1) Preparation of papermaking suspension A fiber dispersion is prepared by dispersing the components listed above, excluding the hydrophilic polymer-adhering aerogel, i.e., the first inorganic fiber, optionally added organic fiber, and other components, in an aqueous medium. A papermaking suspension is prepared by mixing the aqueous slurry or dried product of the aerogel obtained by the hydrophilic polymer adhesion treatment with the above-mentioned fiber dispersion.

[0073] Water is preferred as the aqueous medium used in the fiber dispersion. Other solvents besides water may be included as the aqueous medium, such as aromatic hydrocarbons like toluene, ethers like tetrahydrofuran, ketones like methyl ethyl ketone, alcohols like isopropyl alcohol, N-methyl-2-pyrrolidone (NMP), dimethylacetamide, dimethylformamide, dimethyl sulfoxide, etc., in amounts that do not impair the effects of the present invention (0.1% by weight or less). If a surfactant is included, it is preferable that it be included in an amount that does not impair the effects of the present invention (0.1% by weight or less).

[0074] When using an aqueous slurry of hydrophilic polymer-adhered aerogel, a papermaking suspension can be obtained by mixing and stirring it with the fiber dispersion prepared above. Hydrophobic aerogels tend to aggregate in water and, due to their low specific gravity, are easily separated from fibers. However, when hydrophilic polymers are pre-coated or attached to the aerogel (hydrophilic polymer-coated slurry or its dried form), the hydrophobic aerogel can disperse in the aqueous phase, enabling homogeneous mixing with the fibers. In other words, a papermaking suspension in which hydrophobic aerogel is dispersed can be prepared.

[0075] When using the dried solid (lump or crushed powder) of an aqueous slurry of aerogel obtained by hydrophilic polymer adhesion treatment, the dried solid is directly added to the fiber dispersion and stirred. Even when lumps are added as a dry solid, stirring pulverizes the lumps, and a papermaking suspension is obtained in which powder particles of hydrophilic polymer-attached aerogel are dispersed in a fiber dispersion.

[0076] The solid content concentration of the papermaking suspension should be such that the above components can be uniformly stirred and mixed. Specifically, the solid content is 0.01 to 10% by weight, preferably 0.05 to 3% by weight.

[0077] (2) Wet papermaking (papermaking process) Wet papermaking is a method in which the papermaking suspension prepared above is papered in a papermaking machine, dewatered, and a sheet-like material is obtained. As paper machines, cylinder paper machines, long screen paper machines, inclined paper machines, inclined short screen paper machines, and combinations thereof can be used.

[0078] Dehydration is usually performed by placing the material on a screen mesh or similar surface and using suction. The resulting sheet-like material is typically in a moist state with a moisture content of approximately 70-85% by weight, depending on its composition. The sheet may be further dried if desired, or it may be subjected to a lamination process with a second inorganic fiber substrate while still containing moisture. When drying, it can be carried out by hot air drying, an oven, or contact with a heating roll.

[0079] The sheet for the heat insulating layer in the wet state can function as an adhesive between the inorganic fiber base material (woven fabric, non-woven fabric, or paper) sandwiching the heat insulating layer and the hydrophilic polymer (especially polyvinyl alcohol) adhered to the aerogel due to the affinity therebetween.

[0080] <Coating layer (made of second inorganic fiber base material) B> ​​​​​​​​​​​​​​​​​​​​​​​​In this invention, the inorganic fiber base material (woven fabric, nonwoven fabric, paper) means that the main component (90% by weight or more) is inorganic fiber, and may contain components other than inorganic fiber (organic fiber, binder, etc.) as needed.

[0086] The thickness of the fabric or paper used for the covering layer should be sufficient to prevent powder from falling off the insulation layer and to cover any powderiness caused by inorganic insulating particles exposed on the surface of the insulation layer. Therefore, it should be 0.1 mm or more, 0.2 mm or more, and 1.5 mm or less, preferably 1 mm or less, 0.8 mm or less, or 0.5 mm or less. If it becomes too thick, the air permeability will decrease, and the insulation sheet that forms the laminate will become too thick.

[0087] <Creation of laminated insulation and fire-resistant sheets> The laminated heat-insulating and flame-shielding sheet according to this embodiment can be created by sandwiching both sides of the heat-insulating layer sheet created above between a second inorganic fiber base material (woven fabric, nonwoven fabric, paper) and joining them together.

[0088] The bonding and integration can be achieved by heating and pressurizing the sheet for the insulation layer while it is sandwiched between inorganic fiber sheets for the coating layer.

[0089] In one embodiment, the obtained heat-insulating layer sheet with a moisture content of 70-85% is dried by heating and pressurizing while sandwiched between the second inorganic fiber substrate (woven fabric, nonwoven fabric, or paper). Drying here means that the heat-insulating layer reaches a constant weight state.

[0090] The drying process can be carried out at a temperature that allows the moisture contained in the insulation layer to evaporate. Specifically, it can be done by heating in an oven at 80-140°C for about 30-100 minutes. The heating temperature and time can be set appropriately depending on the composition and moisture content of the insulation layer.

[0091] When polyvinyl alcohol is used as the hydrophilic polymer, the polyvinyl alcohol solidifies during the drying process of the hydrated insulation layer sheet. The solidification of the polyvinyl alcohol present on the surface of the insulation layer allows it to function as a binder between the insulation layer and the coating layer.

[0092] In another embodiment, the obtained heat-insulating layer sheet with a moisture content of 20-85% is heated and pressurized while sandwiched between woven fabric, nonwoven fabric, or paper made of the second inorganic fiber, thereby heating and pressurizing at the softening temperature or melting point of the hydrophilic polymer or organic fiber contained in the heat-insulating layer sheet. The heating temperature is set to a temperature at which the hydrophilic polymer or organic fibers contained in the heat insulating layer sheet can flow and fuse together. This is typically within the range of 120 to 200°C, preferably 150 to 200°C, and is appropriately set depending on the type of hydrophilic polymer or organic fiber used.

[0093] The pressurized pressure ranges from 0.1 to 20 kg / cm². 2 , 0.5~15 kg / cm 2 The pressurization time is appropriately selected according to the heating temperature and press pressure during the pressurization process. Specifically, it can be 5 minutes or more, 10 minutes or more, 20 minutes or more, 5 hours or less, 3 hours or less, 2 hours or less, or about 1 hour.

[0094] The thickness of the heat-insulating and fire-resistant sheet depends on the thickness of the insulation layer and the covering sheet used, and is typically greater than 0.5 mm, 0.8 mm or more, 1 mm or more, 1.3 mm or more, 1.5 mm or more, less than 5 mm, 3 mm or less, 2.5 mm or less, 2.0 mm or less, and 1.8 mm or less.

[0095] In the double-sided coated type heat-insulating and flame-shielding sheet manufactured as described above, the hydrophilic polymer surrounding the hydrophobic aerogel particles at the interface between the heat-insulating layer and the coating layer functions as a binder, enabling bonding and integration with the coating sheet. This avoids moisture absorption on the surface of the coating sheet, the use of a binder for bonding and integration with the sheet, and the presence of a binder layer. This has the advantage of reducing the amount of binder used, which can cause a decrease in heat resistance and heat insulation. Furthermore, since the binder application process is unnecessary, the manufacturing process can be simplified.

[0096] Furthermore, since the aerogel particles that cause powder shedding preferentially bond with the coating layer, powder shedding and surface powderiness can be effectively suppressed even with a reduced amount of binder.

[0097] Furthermore, since there is no binder layer that covers the entire surface of the layer between the insulation layer and the coating layer (inorganic fiber substrate), the inherent air permeability of the inorganic fiber substrate is not impaired. This allows for the exhaust of decomposition gases and other substances that may be generated from the insulation layer by adjusting the air permeability of the inorganic fiber substrate that constitutes the coating layer.

[0098] The laminated heat-insulating and fire-resistant sheet produced in the manner described above has a bulk density of 400 kg / m³, depending on the type of inorganic fiber base material used for covering. 3 Below 300kg / m 3 Below 250kg / m 3 Below 100kg / m 3 More than 150kg / m 3 This can be done.

[0099] <Other Embodiments> In Figure 1, inorganic fiber substrates for covering were laminated on both sides of the insulation layer, but the laminated insulation and flame-retardant sheet of the present invention is not limited to this. For example, if the object to be insulated and flame-retardant is a material to which hydrophilic polymers can adhere, such as a glass plate or a metal plate, the inorganic fiber substrate used as the covering layer may be laminated on only one side of the insulation layer. In this case, the inorganic fiber substrate is laminated on one side of the insulation layer and then heat-pressed from the side of the covering substrate. The opposite side (the side on which the covering substrate is not laminated) may have a plastic film, a metal foil such as aluminum foil attached to it, or it may be directly bonded to the object to which the insulation and flame-retardant sheet is to be applied (glass plate or metal plate).

[0100] <Application> The laminated heat-insulating and flame-resistant sheet of the present invention can be used as: a heat-insulating and flame-resistant sheet to be interposed between battery cells, which are the smallest units of a lithium-ion battery; heat-insulating and flame-resistant for electrical equipment where moisture absorption must be avoided; a partition or isolation sheet to be interposed between the outer casing and the battery pack or battery module when a battery pack or battery module containing multiple lithium-ion battery cells electrically connected in series or parallel is housed in a casing; and a heat-insulating material for the purpose of insulating fire-resistant and fireproof doors during normal use. [Examples]

[0101] [Measurement and evaluation methods] (1) Moisture content of the insulation layer sheet (%) The water content was determined from the solid content during preparation (W0) and the weight of the molded product obtained by papermaking (W1). Moisture content = {(W1-W0) / W0}×100

[0102] (2) Thermal insulation test As shown in Figure 3, a hot plate (100mm x 100mm) 22, continuously heated to 700°C, was placed on a ceramic insulation board (300mm x 300mm x 15mm thick) with a square opening 23a of 100mm on each side. The sheet to be evaluated (150mm x 150mm) 21 was placed on the hot plate 22, and the temperature of the back side (the side that was not heated) of the sheet after holding it for 6 minutes was measured with a temperature sensor 24.

[0103] (3) Powder shedding, surface powderiness After applying a low-tack sheet to the surface of the heat-insulating and flame-retardant sheet, it was peeled off, and the adhesive surface of the tack sheet was image-processed using a microscope to calculate the percentage of the area occupied by foreign matter such as aerogel relative to the total area of ​​the treated region.

[0104] (4) Zygosity As shown in Figure 5, a laminated heat-insulating and fire-resistant sheet, prepared in a strip shape (90 mm x 20 mm), was trimmed by 20 mm from each end, leaving the base material (coating layer) and heat-insulating layer at one end and the base material (coating layer) on the opposite side at the other end. A 50 mm section with three layers of base material (coating layer) and heat-insulating layer on both sides was left in the center to be used as a sample piece. As shown in Figure 5, the cut end of the sample piece prepared above was clamped, and the piece was pulled in the direction of the black arrow using a measuring device (Shimadzu Autograph AGS-X500N), and the stress with respect to the stroke (tensile distance) was measured. The peak value of the obtained stress curve was measured as the joint strength. Based on the obtained measurements (joint strength), the bonding performance was evaluated in the following four stages. The evaluation was performed by measuring the joint strength (N) on both sides of the insulation layer (top and bottom surfaces during papermaking). The bottom surface refers to the surface that comes into contact with the filtration mesh screen used in the dewatering process during the creation of the insulation layer sheet.

[0105] ×: Insufficient bonding with glass cloth makes it difficult to handle as a laminate (2N or less). △: Weak bonding strength with glass cloth, but can be handled as a laminate (approximately 2-5N). ○: Bonded with glass cloth, resulting in good handling properties as a laminate (approximately 5-8N). ◎: Strong bond with glass cloth; in peel strength test, the insulation layer ruptured (over 8N).

[0106] [Creation and Evaluation of Laminated Insulation and Flame-Retardant Sheets I] (1) Preparation of insulation layer sheet (1-1) Preparation of aerogel slurry As the hydrophobic aerogel, Cabot Corporation's hydrophobic aerogel IC3100 was used. This is amorphous silica with a wetting angle of 120-150 degrees (surface area 600-800 m²). 2 / g, porosity 120-150 kg / m 3 , average pore diameter of 20 nm, particle diameter of 2 to 40 μm, and DBP oil absorption of 540 to 650 g / 100 g).

[0107] 1.8 g of polyvinyl alcohol (PVA) fibers (average fiber length 3 mm, saponification degree 95 mol% or more) were added to 80 g of warm water (70-100°C), and the mixture was stirred to prepare a 2.3% warm PVA aqueous solution. 14.5 g of the above-mentioned hydrophobic aerogel was added to this solution, and the mixture was shaken to prepare an aerogel slurry. This aerogel slurry was hydrophilized with an aerogel:polyvinyl alcohol ratio of 6:1 (aerogel solid content: 8.9%).

[0108] (1-2) Preparation of fiber dispersion A fiber dispersion was prepared by adding 12.6g of silica fiber (fiber diameter 9μm, fiber length 3-5mm), 2.0g of glass fiber (E-glass with fiber diameter 5-9μm and length 3-9mm), 2.0g of polyester fiber (fiber diameter 5-10μm, fiber length 3-9mm), 1.4g of colloidal silica (Snowtex 30®), and 2.0g of bentonite to a container containing 900cc of water.

[0109] (1-3) Preparation of papermaking suspension To the fiber dispersion prepared above, 2000g of water was added, and while stirring, 96.3g of the aerogel slurry prepared above was added to prepare a suspension for papermaking.

[0110] (1-4) Preparation of insulation layer sheet The papermaking suspension prepared above was injected into a wet molding machine (filtration mesh screen #80 (mesh opening 180-200 μm)) and dewatered by suction. By vacuum dewatering, a sheet for insulation layer measuring 150mm x 150mm x approximately 2.0mm thick was obtained (bulk density approximately 285.6g / m²). 3 ). The proportion of aerogel in the insulation layer was 60-70% by volume. When this insulation layer sheet was subjected to an insulation performance test, the result was 513°C. Furthermore, when the insulation layer sheet alone was subjected to a powder shedding test, the area occupied by foreign matter was 38%.

[0111] (2) Coating layer (inorganic fiber base material) The following glass cloth or silica fiber paper was used as the inorganic fiber base material. • Glass cloth Plain weave glass cloth from Maeda Glass Co., Ltd. (Model number: EP18) Weight: 184g / m 2 Thickness: 0.18mm, Density: 42 lines vertically and 32 lines horizontally per 25mm. • Silica fiber paper A fiber dispersion containing silica fibers (97%) and PET fibers (3%) used in the insulation layer is wet-processed to produce silica fiber paper with a thickness of 0.5 mm (bulk density 181 kg / m²). 3 I created ).

[0112] (3) Creation and evaluation of laminated insulation and fire-resistant sheets No.1: The insulation layer sheet prepared as described above was placed in a press machine and heat-pressed from both sides under the following conditions: thickness 1.6 mm, bulk density 230 kg / m². 3 The result of the thermal insulation test was 510°C. Heating temperature: 120℃ Press pressure: 1 kg / cm 2 Pressing time: 60 minutes

[0113] A micrograph (500x magnification) of the surface of No. 1 is shown in Figure 4. In Figure 4, it can be confirmed that hydrophilic polymer 3 is attached to the surface of aerogel particles (average particle size approximately 50 μm) 2. Furthermore, it can be confirmed that the aerogel particles 2 are held between the entangled matrix fibers 1 by the attachment of the hydrophilic polymer to the fibers. An evaluation of powder shedding revealed that the area occupied by foreign matter was 1.4%, confirming that heat pressing can suppress powder shedding. Furthermore, there was almost no powdery feeling when touching the surface.

[0114] The thermal insulation test result was 510°C. In terms of thermal insulation performance, it was comparable to that of the thermal insulation sheet alone.

[0115] No.2: The insulation layer prepared as described above was sandwiched between two sheets of silica fiber paper and hot-pressed using a press machine under the same conditions as in No. 1. The thickness was 1.7 mm and the bulk density was 240 kg / m³. 3 The result of the thermal insulation test was 480°C.

[0116] Regarding the resulting laminated insulation and flame-retardant sheet, it was confirmed that the insulation layer and the silica paper were bonded to such an extent that they could not be peeled apart by hand. When evaluating the amount of powder that falls off, the area occupied by foreign matter was 0.09%, and no powdery texture was felt when the surface was touched.

[0117] No.3: An insulating and flame-retardant sheet was obtained in the same manner as in No. 1, except that the covering sheet was changed to fiberglass cloth. It has a thickness of 1.6 mm and a bulk density of 260 kg / m². 3 The result of the thermal insulation test was 420°C. Similar to No. 2, it was confirmed that the insulation layer and the glass cloth were bonded to a degree that they could not be peeled off by hand. Furthermore, when evaluating powder shedding, the area occupied by foreign matter was 0.1%, and no powdery texture was felt when the surface was touched.

[0118] [Preparation and Evaluation of Laminated Insulation and Flame-Retardant Sheets II] No. 4 The aerogel slurry for creating the insulation layer was prepared as follows. Polyvinyl alcohol (PVA) fibers (average fiber length 3 mm, saponification degree 95 mol% or more) were dissolved in warm water (70-100°C) to prepare a 2.5 wt% PVA hot aqueous solution. Hydrophobic aerogel was added to this solution and shaken to prepare an aerogel slurry. The aerogel slurry was hydrophilized with an aerogel:polyvinyl alcohol ratio of 33:4.7 (aerogel solid content 15.4%). A fiber dispersion (dispersion medium: water) having the following composition was prepared. Belco Fiber 32.7g Bentonite 5.2g Glass fiber 10.4g PET fiber 5.2g The aerogel slurry prepared above was added to the fiber dispersion to prepare a papermaking suspension having the following mixing ratio (by weight). Belco Fiber 32.7g Bentonite 5.2g Glass fiber 10.4g PET fiber 5.2g PVA-stabilized aerogel 37.7g (of which PVA 4.7g)

[0119] The papermaking suspension prepared above was injected into a wet molding machine (with a filtration mesh screen #80 (mesh opening 180-200 μm)) and dewatered by suction. By suction dewatering, a thermal insulation layer sheet measuring 250 mm x 250 mm x approximately 1.4 mm thick (moisture content approximately 80%) was obtained.

[0120] As the inorganic fiber base material for the coating layer, we used plain weave glass cloth from Maeda Glass Co., Ltd. (model number: EP18, weight 184g / m²). 2 A material with a thickness of 0.18 mm and a density of 42 strands vertically and 32 strands horizontally per 25 mm was used. The insulation layer sheet created above was placed on top of this glass cloth, and then another layer of glass cloth was placed on top of that. Using a press machine, the sheets were heat-pressed from both sides under the following conditions to create a laminated insulation and flame-resistant sheet. Heating temperature: 120℃ Pressing pressure: 14.2 kg / cm 2 Pressing time: 60 minutes

[0121] No. 5: The aerogel slurry prepared in No. 4 was dried to obtain a lump, which was then added to a fiber dispersion having the same composition as the fiber dispersion used in No. 4. The mixture was stirred to prepare a suspension for papermaking. Using this papermaking suspension, a sheet for the insulation layer was prepared in the same manner as in No. 4. Using the prepared sheet for the insulation layer, a laminated insulation and flame-resistant sheet was prepared in the same manner as in No. 4.

[0122] No. 6 A slurry with an aerogel content of 11.77% was prepared by mixing 14.5 g of hydrophobic aerogel, 108.2 g of water, and 108.7 g of nonionic surfactant (a 0.46% aqueous solution of polyoxyethylene-polyoxypropylene condensate, ADEKA Pluronic® P84). During preparation, significant foaming occurred due to the presence of the surfactant. After adding an antifoaming agent to suppress foaming, the slurry was used to prepare a suspension for papermaking.

[0123] A fiber dispersion having the same composition as the fiber dispersion prepared in No. 4 was mixed with the surfactant-stabilized aerogel slurry prepared above to obtain a papermaking suspension having the following composition. Belco Fiber 32.7g Bentonite 5.2g Glass fiber 10.4g PET fiber 5.2g Surfactant-stabilized aerogel 37.6g (of which surfactant 1.3g)

[0124] Using this papermaking suspension, an insulating layer sheet was prepared in the same manner as in No. 4. Using the prepared insulating sheet, a laminated insulating and flame-resistant sheet was prepared in the same manner as in No. 4.

[0125] No. 7 A 10% aqueous PVA solution was prepared by dissolving polyvinyl alcohol powder (Gosenol® KL-05) in warm water (approximately 80°C). The above 10% PVA warm water solution was added to the papermaking suspension prepared in No. 6 and mixed to prepare a papermaking suspension. The PVA content in the papermaking suspension was 4.7 g.

[0126] Using the obtained papermaking suspension, a sheet for the insulation layer was prepared in the same manner as in No. 4. When a laminated insulation and flame-resistant sheet was prepared using the prepared insulation layer sheet in the same manner as in No. 4, the glass cloth did not bond to the underside of the insulation layer, and it was not possible to create a sandwich-type laminated insulation and flame-resistant sheet.

[0127] For the laminated insulation and fire-resistant sheets No. 4-7 created as described above, the bonding strength between the insulation layer and the covering layer was measured and evaluated. For sheets No. 6 and 7, the bonding strength of the upper surface was measured by pulling only the upper surface where the insulation layer and the covering layer were joined in the direction of the arrow. The evaluation results are shown in Table 1.

[0128] [Table 1]

[0129] Cases No. 6 and No. 7 involve the use of a surfactant as a dispersant for the hydrophobic aerogel, and in case No. 7, a papermaking suspension is prepared by adding a warm aqueous solution of polyvinyl alcohol afterwards. Neither No. 6 nor No. 7 bonded to the inorganic fiber substrate used as the coating layer on their underside (the surface that contacted the mesh filter during the suction dewatering process). Bonding occurred on the upper surface (the side that did not contact the mesh filter during the suction dewatering process), but the bond was weak enough to be easily peeled off by hand (peel strength less than 1N). It is thought that the papermaking suspension did not contain any binder components, which prevented it from bonding to the substrate. On the other hand, in No. 7, the PVA aqueous solution was added and mixed separately from the aerogel stabilization treatment. The evaluation results for bonding performance were the same as in No. 6, suggesting that the PVA aqueous solution added later was washed away during the papermaking process (suction dewatering process) and was unable to perform its role as a binder. On the other hand, samples No. 4 and 5, which were pre-dispersed with polyvinyl alcohol to prepare hydrophilic polymer-attached aerogel particles, were able to bond to the substrate on both the top and bottom surfaces. In the case of No. 4, there was a difference in bonding strength between the top and bottom surfaces, but in the case of No. 5, the bonding strength between the top and bottom surfaces was about the same. It is thought that the dispersion homogeneity of the aerogel was higher when the aerogel slurry was mixed with the fiber dispersion (No. 5) than when the aerogel slurry was mixed with the fiber dispersion (No. 4). [Industrial applicability]

[0130] The laminated heat-insulating and flame-resistant sheet of the present invention exhibits high heat insulation performance by containing a large amount of highly porous particles such as aerogel particles. Since the surface of the heat-insulating layer is covered with an inorganic fiber substrate, there are no problems with powder shedding or powderiness. Moreover, the hydrophilic polymer used to stabilize the dispersion of the hydrophobic aerogel also contributes to bonding the heat-insulating layer and the coating layer, so it exhibits superior heat insulation and flame resistance compared to heat-insulating sheets that use an adhesive layer, which can reduce heat insulation performance. [Explanation of symbols]

[0131] A: Insulation layer (insulation sheet) B: Coating layer (inorganic fiber base material) 1. Inorganic fiber for matrix (first inorganic fiber) 2. Hydrophobic aerogel particles 3 Hydrophilic polymer

Claims

1. A laminated thermal insulation and flame-shielding sheet in which a second inorganic fiber substrate is laminated on both sides of a thermal insulation layer in which thermal insulation particles are held within a first group of entangled inorganic fibers, The aforementioned heat-insulating particles are hydrophilic polymer-attached aerogel particles, in which a hydrophilic polymer is attached to at least a portion of the surface of the hydrophobic aerogel particles. A laminated heat-insulating and flame-shielding sheet in which the heat-insulating layer and the coating layer are joined by the hydrophilic polymer.

2. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the first inorganic fiber is at least one selected from the group consisting of silica fiber, silica-alumina fiber, alumina fiber, mullite fiber, zirconia fiber, silicon carbide fiber, biosoluble fiber (AES), refractory ceramic fiber (RCF), ceramic fiber, glass fiber, rock wool, carbon fiber, and graphite fiber.

3. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the fiber length of the first inorganic fiber is 3.0 mm to 15 mm.

4. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the inorganic fiber base material is a glass fiber woven fabric, nonwoven fabric, or paper.

5. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the hydrophobic aerogel particles are silica aerogel with a pore size of 20 nm or less and a porosity of 80% or more.

6. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the hydrophilic polymer is polyvinyl alcohol.

7. The laminated heat insulating and flame-shielding sheet according to claim 1, wherein in the hydrophilic polymer-attached aerogel particles, the weight ratio of the hydrophilic polymer to the aerogel particles (hydrophilic polymer / aerogel particles) is 1 / 1 to 1 / 30.

8. The laminated heat-insulating and flame-shielding sheet according to claim 1, wherein the heat-insulating layer is paper made by wet-processing a suspension containing the first inorganic fibers and the hydrophilic polymer-adhered aerogel particles.

9. A method for manufacturing a laminated heat-insulating and flame-shielding sheet as described in claim 1, A process of papermaking a sheet with a water content of 70-85% by mixing an aqueous slurry containing a hydrophobic aerogel and a hydrophilic polymer with a first fiber dispersion liquid in which first inorganic fibers are dispersed in an aqueous medium; A manufacturing method comprising the step of drying the obtained insulation layer sheet by heating and pressurizing it while sandwiching both sides between a second inorganic fiber substrate.

10. A method for manufacturing a laminated heat-insulating and flame-shielding sheet as described in claim 1, A step of preparing an aqueous suspension in which the pulverized aerogel material is dispersed among the first inorganic fibers by adding a lump of hydrophilic polymer-attached aerogel to a first fiber dispersion liquid in which the first inorganic fibers are dispersed in an aqueous medium, and then stirring to pulverize the lump; A step of papermaking the aqueous suspension to obtain a sheet with a water content of 70-85%; A manufacturing method comprising the step of drying the obtained sheet by heating and pressurizing it while sandwiching both sides of the sheet between a second inorganic fiber substrate.

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