Laminate and heat insulating material for piping

Abstract

Provided is a laminate or the like comprising: at least one aerogel composite layer containing a porous substrate and an aerogel filled inside the porous substrate; and at least one metal layer.

Description

Laminates and insulation materials for piping

[0001] This disclosure relates to laminates and insulation materials for piping.

[0002] For insulating low-temperature structures such as low-temperature piping and tanks, or for preventing condensation on their surfaces, methods include covering the outer perimeter of the low-temperature structure with insulating material or adopting a vacuum insulation structure.

[0003] For example, Patent Document 1 describes a heat insulating sheet comprising a resin film having a metal layer and a nonwoven fabric containing resin fibers, wherein the resin film and the nonwoven fabric are joined by through holes penetrating the resin film and the nonwoven fabric, and the ratio (La / Lb) of the average distance between through holes in the resin film (La) to the average distance between through holes in the nonwoven fabric (Lb) is 1.0010 or more and 1.10 or less.

[0004] Patent Document 1: Patent No. 7219259

[0005] However, when insulation materials absorb water due to condensation, their thermal insulation performance deteriorates, requiring replacement. Furthermore, while vacuum insulation is useful for thermal insulation and condensation prevention, it increases the overall outer diameter of the low-temperature structure, leading to a larger overall equipment size.

[0006] One embodiment of this disclosure aims to solve the problem of providing laminates and piping insulation materials that are less prone to condensation.

[0007] This disclosure includes the following embodiments: <1> A laminate comprising a porous substrate, at least one aerogel composite layer containing an aerogel filled inside the porous substrate, and at least one metal layer. <2> The laminate according to <1>, wherein the aerogel composite layer is the outermost layer. <3> The laminate according to <1> or <2>, wherein the thickness of the metal layer is 100 μm or less. <4> The laminate according to any one of <1> to <3>, wherein the metal layer contains aluminum. <5> A pipe insulation material comprising the laminate according to any one of <1> to <4>.

[0008] According to one embodiment of the present disclosure, a laminate and a pipe insulation material that are less prone to condensation are provided.

[0009] The contents of this disclosure will be described in detail below. The explanation of the constituent elements described below may be based on representative embodiments of this disclosure, but this disclosure is not limited to such embodiments. In this disclosure, numerical ranges indicated using "~" mean a range that includes the numbers indicated before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0010] In this disclosure, the amount of each component in a composition means the total amount of any multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this disclosure, the term "process" includes not only independent processes but also any process that is not clearly distinguishable from other processes, as long as its intended purpose is achieved.

[0011] [Laminate] The laminate of the present disclosure comprises a porous substrate, at least one aerogel composite layer containing an aerogel filled inside the porous substrate, and at least one metal layer.

[0012] The laminate of this disclosure is less prone to condensation. The laminate of this disclosure has excellent thermal insulation properties due to the combination of the aerogel composite layer and the metal layer. For example, by covering a pipe carrying a fluid at a lower temperature than the outside air with the laminate of this disclosure, condensation is less likely to occur.

[0013] <Layer Structure> The laminate of this disclosure may consist of only one aerogel composite layer or two or more layers. Furthermore, the laminate of this disclosure may consist of only one metal layer or two or more layers.

[0014] The laminate of this disclosure may include layers other than the aerogel composite layer and the metal layer. Examples of other layers include a foam layer.

[0015] Examples of foams included in the foam layer include polyolefin foam, EPDM (ethylene propylene diene rubber) foam, urethane foam, silicone foam, and polyvinyl chloride foam.

[0016] It is preferable that the structure consists of an aerogel composite layer and a metal layer, as this reflects radiant heat from the outside.

[0017] Examples of layer configurations include the following: Configuration 1: Aerogel composite layer / Metal layer Configuration 2: Aerogel composite layer / Metal layer / Aerogel composite layer Configuration 3: Metal layer / Aerogel composite layer / Metal layer / Aerogel composite layer Configuration 4: Aerogel composite layer / Metal layer / Aerogel composite layer / Metal layer / Aerogel composite layer Configuration 5: Metal layer / Aerogel composite layer / Metal layer Configuration 6: Aerogel composite layer / Metal layer / Foam layer / Metal layer / Foam layer

[0018] In particular, when the laminate of this disclosure is used as an insulating laminate for covering an object to be insulated, it is preferable that the aerogel composite layer be the outermost layer from the viewpoint of trapping the cold air generated from the object to be insulated.

[0019] When the laminate of the present disclosure comprises two or more aerogel composite layers, it is preferable that at least one of the two outermost layers in the laminate is an aerogel composite layer. For example, if one outermost layer is an aerogel composite layer and the other outermost layer is a metal layer, condensation can be made less likely to occur by covering the object to be insulated with the laminate of the present disclosure such that the metal layer side is in contact with the object to be insulated.

[0020] From the viewpoint of further suppressing the occurrence of condensation, the layer configuration of the laminate of this disclosure is preferably configuration 1 to 4, more preferably configuration 3 or configuration 4, and even more preferably configuration 4.

[0021] That is, the laminate of the present disclosure preferably includes a first aerogel composite layer, a first metal layer, a second aerogel composite layer, and a second metal layer in this order, and more preferably further includes a third aerogel composite layer on the second metal layer.

[0022] In addition, the layer structure of the laminate of the present disclosure may have a foam layer as the outermost layer as in the above-described configuration 6. When the foam layer is the outermost layer, the foam layer preferably contains a polyolefin foam. Since polyolefin has high water repellency, dew condensation is unlikely to occur.

[0023] The thickness of the laminate of the present disclosure is not particularly limited, but from the viewpoint of moldability, it is preferably 1 mm to 10 mm, and more preferably 2 mm to 5 mm. Also, the thinner the laminate, the higher the selectivity of the use location and the better the workability.

[0024] Hereinafter, the aerogel composite layer and the metal layer will be described.

[0025] <Aerogel Composite Layer> The aerogel composite layer includes a porous substrate and an aerogel filled inside the porous substrate.

[0026] (Porous Substrate) The porous substrate is not particularly limited as long as it is a substrate having a plurality of pores. An aerogel described later is filled inside the porous substrate.

[0027] The size of the pores of the porous substrate is not particularly limited. The pores of the porous substrate may be micropores, mesopores, or macropores.

[0028] The pores of the porous structure may be independent pores or communicating pores. From the viewpoint of easily filling the aerogel inside, the porous substrate preferably includes communicating pores.

[0029] Examples of porous substrates include foams, fibrous substrates (e.g., woven fabrics, nonwoven fabrics, etc.), and porous ceramic substrates. From the viewpoint of balancing the thermal insulation, processability, and ease of manufacture of the aerogel composite layer, the porous substrate is preferably a foam or nonwoven fabric, and from the viewpoint of improving the retention of the aerogel, it is more preferably a foam.

[0030] Examples of fibers constituting the fibrous base material include metal fibers made of metals such as stainless steel and aluminum; organic fibers made of organic materials such as polyester, polyolefin, polyvinyl chloride, acrylic, polyimide, polyamide, and cellulose; and inorganic fibers made of inorganic materials such as glass, carbon, silica, rock wool, and ceramics.

[0031] The foam is preferably an open-cell resin foam having an open-cell structure. When the foam is an open-cell resin foam, it is easier to fill the inside of the foam with aerogel.

[0032] Examples of resins that make up the foam include polyolefins, polystyrenes, polyesters, polyethers, acrylic resins, polyamides, vinyl chloride resins, polycarbonate resins, melamine resins, and fluororesins. Among these, polyolefins are preferred as the resin that makes up the foam.

[0033] The foam may be heat-compressed. The foam may also have a skin layer. The skin layer is generally a region with a higher density (fewer bubbles) than the center of the foam.

[0034] For methods of thermally compressing the foam and forming a surface layer on the foam, the methods disclosed in Japanese Patent Publication No. 2022-011146, etc., can be used.

[0035] The density of the porous substrate is 0.01 g / cm³. ３ Above, 0.02g / cm ３ Above, 0.05g / cm ３ Above, 0.08g / cm ３ Above, or 0.10 g / cm³ ３It is preferably as described above. Further, the density of the porous substrate is 2.0 g / cm ３ or less, 1.0 g / cm ３ or less, 0.80 g / cm ３ or less, 0.60 g / cm ３ or less, 0.40 g / cm ３ or less, or 0.25 g / cm ３ or less, which is preferable. When the density of the porous substrate is within the above range, the heat insulation property is excellent.

[0036] The thickness of the porous substrate can be appropriately changed according to the application and is not particularly limited. From the viewpoint of enhancing the heat insulation property, workability, ease of manufacture, etc. of the aerogel composite layer in a well-balanced manner, the thickness of the porous substrate is preferably 0.1 mm or more, 0.2 mm or more, 0.5 mm or more, or 1.0 mm or more. Further, the thickness of the porous substrate is preferably 100.0 mm or less, 50.0 mm or less, 20.0 mm or less, 10.0 mm or less, or 5.0 mm or less.

[0037] The aerogel composite layer includes a porous substrate and an aerogel filled inside the porous substrate, and the thickness of the aerogel composite layer can be regarded as equivalent to the thickness of the porous substrate.

[0038] The shape of the porous substrate can be appropriately changed according to the application and is not particularly limited.

[0039] (Aerogel) The aerogel is filled inside the porous substrate. In the present disclosure, the aerogel refers to a substance obtained by replacing the solvent contained in the gel with a gas (for example, air).

[0040] Examples of the aerogel include inorganic aerogels such as silica aerogel and alumina aerogel; organic aerogels such as resorcinol-formaldehyde aerogel (RF aerogel) and cellulose nanofiber aerogel (CNF aerogel); carbon aerogel, and mixtures thereof. The aerogel is preferably silica aerogel.

[0041] The density of the aerogel is 0.001 g / cm ３ or more, 0.01 g / cm３ Above, 0.05g / cm ３ Above, 0.08g / cm ３ Above, or 0.10 g / cm³ ３ It is preferable that the above is true. Furthermore, the density of the aerogel is 2.0 g / cm³. ３ Below, 1.0g / cm ３ Below, 0.80g / cm ３ Below, 0.60g / cm ３ Below, 0.40g / cm ３ Below, 0.25g / cm ３ The following, or 0.20 g / cm³ ３ The following is preferable. When the density of the aerogel is within the above range, it has excellent heat insulation properties.

[0042] Aerogel composites can be manufactured, for example, by carrying out the following steps: (1) Sol preparation step to prepare a sol solution; (2) Filling step to fill a porous substrate with the sol solution; (3) Gel preparation step to gel the sol solution in the porous substrate to prepare a wet gel; (4) Solvent replacement step to replace the water in the wet gel in the porous substrate with a non-aqueous solvent; (5) Hydrophobization step to hydrophobize the surface of the wet gel in the porous substrate; (6) Drying step to dry the wet gel in the porous substrate to prepare an aerogel.

[0043] The resulting silica aerogel composite may be further processed into a desired shape.

[0044] The above process may be carried out continuously or intermittently, or multiple processes may be carried out simultaneously.

[0045] The following describes each step in order. While the following details the manufacturing method of silica aerogel composites, aerogel composites containing aerogels other than silica aerogel can also be manufactured using the same method, except for changes in the raw materials.

[0046] (Sol preparation process) The sol preparation process is a process of preparing a sol solution by adding various raw materials, including the main component (silica raw material), to a predetermined solvent and stirring to mix them.

[0047] -Main component- The main component is not particularly limited as long as it is a component that serves as a raw material for silica aerogel, and examples include alkali metal silicates and alkoxysilanes.

[0048] Examples of alkali metal silicates include potassium silicate and sodium silicate. For example, sodium silicate is Na ２ O・nSiO ２ ・mH ２ It is represented by the molecular formula of O. The coefficient n is SiO ２ Na ２ This is the molar ratio of O, and the coefficient m is Na ２ H relative to O ２ This is the molar ratio of O, and SiO ２ and Na ２ The relationship between the mass ratio and molar ratio of the O component is given by the following equation 1. (Equation 1) Molar ratio = (a / b) × 1.032 In equation 1, a is SiO ２ The mass of b is Na ２ This is the mass of O. Also, the constant 1.032 is SiO ２ Molecular weight and Na ２ This is the ratio of the molecular weight to O. Generally, the molar ratio (n value) of manufactured sodium silicate is 0.5 to 5.0. Sodium silicate is Na ２ O・nSiO ２ Any structure shown in the formula is acceptable, and the n value is not particularly limited. The n value of sodium silicate is preferably 0.5 to 5.0 because it is readily available, but it may also be outside the range of 0.5 to 5.0, which is not generally manufactured. Sodium silicate can be used as an aqueous solution by dissolving it in water, for example, before mixing it with other raw materials. In that case, if the n value is less than 1, it is crystalline and does not dissolve easily in water, so a value of 1.0 to 5.0, which dissolves easily in water, is more preferable.

[0049] The alkoxysilane is not particularly limited, and difunctional, trifunctional, or tetrafunctional alkoxysilanes can be used individually or in combination. Examples of difunctional alkoxysilanes include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, diphenyldimethoxysilane, methylphenyldiethoxysilane, methylphenyldimethoxysilane, diethyldiethoxysilane, and diethyldimethoxysilane. Examples of trifunctional alkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. Examples of tetrafunctional alkoxysilanes include tetramethoxysilane and tetraethoxysilane. In addition, bistrimethylsilylmethane, bistrimethylsilylethane, bistrimethylsilylhexane, vinyltrimethoxysilane, etc. can also be used as alkoxysilanes. Furthermore, partial hydrolysates of alkoxysilanes may be used as raw materials.

[0050] -Solvent- Examples of solvents include water, alcohols (methanol, ethanol, isopropanol, tert-butanol, etc.), aprotic polar organic solvents (N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, etc.), hydrocarbons (n-hexane, heptane, etc.), fluorine-containing solvents (2H,3H-decafluoropentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, etc.), and mixtures thereof. When alkoxysilane is used as the main ingredient, the hydrolysis and polymerization of the alkoxysilane are preferably carried out in the presence of water, and more preferably using a mixture of water and an organic solvent that is compatible with water and dissolves the alkoxysilane (making it possible to carry out the hydrolysis and polymerization steps in succession). Here, the solvent that is compatible with water and dissolves the alkoxysilane is not particularly limited, and examples include alcohols such as methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and tert-butanol; acetone, N,N-dimethylformamide, etc. One solvent may be used alone, or two or more may be used in combination.

[0051] - Catalyst - In the sol preparation step, a catalyst may be added in addition to the main component.

[0052] The catalyst may be a basic catalyst or an acidic catalyst. Examples of basic catalysts include ammonia; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide (TMAH); amines such as trimethylamine; alkali hydroxides such as sodium hydroxide; alkali metal carbonates such as sodium carbonate and sodium bicarbonate; and alkali metal silicates. Examples of acidic catalysts include hydrochloric acid, citric acid, nitric acid, sulfuric acid, and ammonium fluoride. Among these, ammonia, tetraalkylammonium hydroxide, or an amine are preferred catalysts, with ammonia being more preferred, because they do not contain metal elements and do not require washing with water.

[0053] The amount of catalyst is not particularly limited, as long as it is sufficient to adequately gel the sol solution.

[0054] - Surfactants - In the sol preparation step, surfactants may be added in addition to the main component. Surfactants contribute to the formation of the bulk portion and pore portion that constitute the aerogel in the gel preparation step described later. Examples of surfactants include nonionic surfactants and ionic surfactants (e.g., cationic surfactants, anionic surfactants, and zwionic surfactants).

[0055] (Filling process) The filling process is the process of filling a porous substrate with a sol solution.

[0056] The filling process can be carried out, for example, by impregnating a porous substrate with a sol solution. In this case, the impregnation time and other factors should be adjusted as appropriate so that the sol solution is sufficiently filled into the porous substrate. Furthermore, vibration may be applied to the sol solution to promote the filling of the porous substrate with the sol solution.

[0057] (Gel Preparation Process) The gel preparation process is a process of gelling a sol solution filled in a porous substrate, that is, a process of obtaining a gel composite in which a wet gel is filled in a porous substrate.

[0058] If a catalyst is added to the sol solution during the sol preparation process, the sol solution can be converted into a wet gel by allowing the sol solution, which is filled into a porous substrate, to stand.

[0059] Furthermore, the catalyst may be added to the sol solution after the filling process.

[0060] Furthermore, the gel preparation step is not limited to adding a catalyst to a sol solution. For example, the gel preparation step may involve heating the sol solution to a high temperature to carry out hydrolysis or condensation polymerization.

[0061] The gel preparation step may include a step of forming a W / O emulsion in order to prepare a spherical aerogel. Specifically, this step is a step of forming a W / O emulsion by dispersing an aqueous sol solution in a hydrophobic solvent. In other words, it is a step of forming an emulsion using an aqueous sol solution as the dispersion phase and a hydrophobic solvent as the dispersion medium.

[0062] By forming such a W / O emulsion, the dispersed sol solution becomes spherical due to surface tension, etc. In this state, a spherical gel can be obtained by gelling the sol solution dispersed in the hydrophobic solvent in this spherical shape. Here, it is preferable to add a surfactant when forming the W / O emulsion. Any of anionic surfactants, cationic surfactants, or nonionic surfactants can be used.

[0063] (Solvent Replacement Process) The solvent replacement process is a process in which water (or water and organic solvent) on the surface and inside of the gel is replaced with a non-aqueous solvent in order to suppress shrinkage of the gel (wet gel) during the drying process.

[0064] A non-aqueous solvent is a solvent other than water. Preferably, the non-aqueous solvent is a polar solvent that is compatible with water. Examples of non-aqueous solvents include methanol, ethanol, n-propanol, isopropanol, 1-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, xylene, 1,2-dimethoxyethane, acetonitrile, hexane, toluene, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, methylene chloride, N,N-dimethylformamide, dimethyl sulfoxide, perfluorohexane, perfluorooctane, methyl nonafluorobutyl ether, and other fluorinated solvents. Non-aqueous solvents may be used alone or in mixtures of two or more types.

[0065] The solvent replacement step may be performed once or multiple times. From the viewpoint of environmental impact, workability, and cost reduction, one solvent replacement is preferable. If multiple solvent replacements are performed, different solvents may be used in each replacement. For example, an organic solvent with a surface tension (hereinafter referred to as ST) of 45 mN / m or less at 20°C may be used as the solvent immediately before the drying step. For example, such organic solvents include fluorinated solvents such as dimethyl sulfoxide (ST: 43.5 mN / m), cyclohexane (ST: 25.2 mN / m), isopropanol (ST: 21 mN / m), heptane (ST: 20.2 mN / m), pentane (ST: 15.5 mN / m), ethanol (ST: 22.4 mN / m), methanol (ST: 22.6 mN / m), perfluorohexane (ST: 12 mN / m), perfluorooctane (ST: 15 mN / m), and methyl nonafluorobutyl ether (ST: 13.6 mN / m).

[0066] The amount of solvent used in each solvent replacement step is, for example, between 2 and 1000 times the volume of the gel complex. The solvent replacement method may be total replacement, partial replacement, or cyclic replacement.

[0067] A dehydrating agent may be used in the solvent replacement step.

[0068] The degree of hydrophobicity of the silica aerogel composite can be increased by changing the type of dehydrating agent used in the solvent replacement process, increasing the amount of dehydrating agent used, or increasing the application time of the dehydrating agent (or the number of times the solvent replacement process is performed).

[0069] (Hydrophobicization process) The hydrophobicization process is a process in which the surface of the aerogel is made hydrophobic with a hydrophobic agent (e.g., a silylate or functional silane) to prevent the hydroxyl groups present on the inner wall of the gel from dehydrating and condensing together during drying, causing shrinkage.

[0070] Examples of functional silanes include a group of silicon compounds composed of chlorosilanes, alkoxysilanes, and silazanes.

[0071] (Drying Process) The drying process involves drying the gel to obtain silica aerogel. There are no particular restrictions on the drying method, and examples include supercritical drying, atmospheric pressure drying, and freeze-drying. Among these, supercritical drying is preferred.

[0072] <Metal Layer> The metals constituting the metal layer are not particularly limited and include aluminum, silver, copper, and stainless steel. From the viewpoint of thermal insulation, it is preferable that the metal constituting the metal layer includes aluminum, and more preferably aluminum.

[0073] The thickness of the metal layer is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, particularly preferably 30 μm or less, extremely preferably 20 μm or less, and most preferably 10 μm or less. A metal layer thickness of 100 μm or less provides excellent flexibility to the laminate of this disclosure. When the laminate of this disclosure is used to cover an object to be insulated, adhesion to the object is enhanced, resulting in a high effectiveness in suppressing condensation.

[0074] The laminate of this disclosure may include layers other than the aerogel composite layer and the metal layer. Examples of other layers include adhesive layers. The adhesive layer is preferably provided between the aerogel composite layer and the metal layer. The adhesive layer is formed by, for example, double-sided tape, liquid adhesive, hot-melt adhesive, etc.

[0075] <Method for Manufacturing the Laminate> The method for manufacturing the laminate according to this disclosure is not particularly limited. For example, a laminate comprising an aerogel composite layer and a metal layer can be obtained by attaching a metal sheet to an aerogel composite.

[0076] When attaching a metal sheet to the aerogel composite, double-sided tape, liquid adhesive, or hot-melt adhesive may be used.

[0077] <Applications> The laminate of this disclosure is less prone to condensation compared to conventional thermal insulation materials. Therefore, it is preferable to use it in equipment that circulates gases or liquids at a temperature lower than the ambient air. Specifically, the laminate of this disclosure is preferable to use by covering equipment such as piping (e.g., cryogenic gas piping) and tanks (e.g., cryogenic storage tanks for hydrogen). Furthermore, because the laminate of this disclosure has excellent thermal insulation properties, it can also be used in equipment that circulates gases or liquids at a temperature higher than the ambient air.

[0078] [Pipe Insulation Material] The pipe insulation material of this disclosure comprises the laminate of this disclosure. Compared with conventional heat insulation materials, the pipe insulation material of this disclosure is less prone to condensation. When a gas or liquid at a lower temperature than the outside air is circulated through the pipe, condensation is less likely to occur, and the frequency of replacement can be reduced.

[0079] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited in any way by these examples.

[0080] <Preparation of Aerogel Composite> (Sol Preparation Process) Tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the main component. 7.2 moles of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 4 moles of ion-exchanged water (electrical resistivity 1 × 10⁻¹⁰) are added per mole of the main component. １０ A sol solution was prepared by mixing a saturation level of Ω·cm or higher with 0.01 moles of catalyst (25% by mass aqueous ammonia (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)).

[0081] (Filling Process / Gel Preparation Process) The foam substrate described below was cut to a width of 210 mm and a length of 3 m and placed in a separable flask. Sol solution was added until the foam substrate was completely immersed (filling process). It was left to stand for 3 hours under atmospheric pressure to obtain a foam substrate filled with wet gel (gel preparation process).

[0082] (Method for preparing foamed substrate) Foamed substrate: 58 parts by mass of random-type polypropylene, 15 parts by mass of low-density polyethylene, 20 parts by mass of EPDM (ethylene content 29.5%, diene content 5%), 1.5 parts by mass of polyoxyethylene stearylamine, 5 parts by mass of wet silica, and 0.2 parts by mass of phenolic antioxidant were melt-kneaded, impregnated with carbon dioxide in a supercritical state, and then the pressure was released to foam and extrude to obtain a foamed substrate which is a polyolefin foam. The manufacturing conditions were an impregnation temperature of 180°C, an impregnation pressure of 13 MPa, and an impregnation time of 20 minutes.

[0083] (Solvent replacement process) The polyolefin foam filled with wet gel was immersed in ethanol, and solvent replacement was carried out for 24 hours while stirring.

[0084] (Hydrophobicization process) To hydrophobize the gel surface within the foamed substrate after solvent replacement, the substrate was immersed in an ethanol solution of hexamethyldisilazane (20% by mass concentration) and subjected to a hydrophobicization treatment for 24 hours while stirring.

[0085] (Drying process) The substrate, whose gel surface was made hydrophobic, was impregnated in carbon dioxide at 80°C and 20 MPa, and supercritical drying was performed for 12 hours to obtain an aerogel composite.

[0086] <Preparation of Metal Foil> As the metal foil, we used aluminum foil (width 210 mm, length 3 m, thickness 15 μm) manufactured by Takumi Giken Co., Ltd.

[0087] <Preparation of the foam> Polyolefin foam: Product name "P-E-Lite RP-300S", thickness 5 mm, density 30 kg / m³ ３ Inoac Corporation EPDM foam: Product name "Gomusupo E-4088", thickness 5 mm, density 100 kg / m³ ３ Manufactured by Inoac Corporation

[0088] <Fabrication of Laminates> In Examples 1 to 4, a laminate comprising an aerogel composite layer and a metal layer (aluminum layer) was fabricated by bonding an aerogel composite and aluminum foil using double-sided tape to achieve the layer configuration shown in Table 1. In Examples 5 and 6, a laminate comprising an aerogel composite layer, a metal layer (aluminum layer), and a foam layer was fabricated by bonding an aerogel composite, aluminum foil, and foam using double-sided tape to achieve the layer configuration shown in Table 1. In Table 1, the aerogel composite layer is referred to as "Layer A," and the metal layer as "Layer B." The polyolefin foam layer is referred to as "C1," and the EPDM foam layer as "C2."

[0089] In Examples 1 to 6, the following evaluations were performed using the prepared laminates. In Comparative Example 1, an aerogel composite was used instead of the laminate, and the same evaluation as in Examples 1 to 6 was performed. Comparative Example 2 was a blank test. In Comparative Example 3, an aerogel composite and a foam were bonded together using double-sided tape to create a laminate comprising an aerogel composite layer and a foam layer, as shown in Table 1.

[0090] (Presence or absence of condensation) The fabricated laminate was wrapped around a pipe to obtain a coated pipe for evaluation. When wrapping the laminate around the pipe, in Examples 1 to 4, the laminate was placed around the outer circumference of the pipe so that layer A was the outermost layer. In Examples 5 and 6, the laminate was placed around the outer circumference of the pipe so that layer C1 or layer C2 was the outermost layer. A thermometer was attached to the surface of the coated pipe to measure the surface temperature. The surface temperature was 23°C. A liquid at -20°C was flowed through the pipe for 30 minutes. The relationship between the elapsed time and the surface temperature was recorded, with the start of liquid flow as the reference point. In addition, the presence or absence of condensation on the surface of the coated pipe was visually observed. If no condensation occurred during the 30 minutes, it was judged as "A", and if condensation occurred, it was judged as "B".

[0091] (Time of condensation occurrence) When condensation occurred, the time of occurrence was recorded.

[0092] (Saturation Temperature) In a graph with elapsed time on the horizontal axis and surface temperature on the vertical axis, the temperature at which the change in surface temperature over time became 1°C / min or less was recorded.

[0093]

[0094] As shown in Table 1, in Examples 1 and 2, the condensation time was longer and condensation was less likely to occur compared to Comparative Examples 1 to 3. In Examples 3 and 4, condensation was even less likely to occur. In Example 5, which contained a polyolefin foam layer, condensation was less likely to occur compared to Example 6.

[0095] The disclosure of Japanese Patent Application No. 2024-180226, filed on 15 October 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A laminate comprising a porous substrate, at least one aerogel composite layer containing an aerogel filled inside the porous substrate, and at least one metal layer.

2. The laminate according to claim 1, wherein the aerogel composite layer is the outermost layer.

3. The laminate according to claim 1, wherein the thickness of the metal layer is 100 μm or less.

4. The laminate according to claim 1, wherein the metal layer comprises aluminum.

5. A pipe insulation material comprising a laminate according to any one of claims 1 to 4.

Images