Complex and heat insulator

Abstract

To provide: a complex which is capable of inhibiting dropout of aerogel particles and is excellent in adhesion with respect to an adhesive; and a heat insulator.SOLUTION: A complex includes: a porous base material; aerogel filled in a cavity of the porous base material; and a hot melt film that covers at least a part of a surface of the porous base material. A coefficient of contraction of the hot melt film when heated at 90°C for one minute is less than 10%. A heat insulator includes the complex.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a composite and a heat insulating material.

Background Art

[0002] A heat insulating material is used for the purpose of suppressing the temperature rise of electronic components such as home appliances and mobile devices. In recent years, a material obtained by compounding an aerogel having excellent heat insulating properties with a nonwoven fabric, a resin foam, or the like is preferably used as a heat insulating material.

[0003] On the other hand, such a heat insulating material has a problem that the aerogel is inferior in mechanical strength, and due to its fragility, aerogel particles are easily detached (powder fall), so that it is easy to contaminate equipment and the like during manufacturing. Further, when used as a heat insulating material, the detached aerogel particles enter the inside of a mobile device or the like, causing a failure. Furthermore, when a pressure-sensitive adhesive such as a double-sided tape is attached to the heat insulating material for use, the adhesion to the pressure-sensitive adhesive is reduced due to the detached aerogel particles.

[0004] In order to solve the above-described problems caused by aerogels, for example, the technique of Patent Document 1 has been proposed. That is, it is a heat insulating material in which the surface of a composite layer in which a porous body such as a foam, a fiber, or a nonwoven fabric is filled with an aerogel is coated with a coating film containing a hydrophilic resin and a lipophilic resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the technology of Patent Document 1 has a structure coated with a coating film, for example, when applied to a curved portion, there is a risk of cracks on the surface. Further, even if the coating paint is applied to the composite layer, the portion containing the water-soluble resin is repelled from the composite layer, resulting in a portion not covered with the coating film. For this reason, the detachment of aerogel particles cannot be sufficiently suppressed, and the adhesion to an adhesive such as a double-sided tape is poor.

[0007] Therefore, an object of the present invention is to provide a composite and a heat insulating material that can suppress the detachment of aerogel particles and have excellent adhesion to an adhesive.

Means for Solving the Problems

[0008] The present inventor has conducted intensive research and found that a composite coated with a hot melt film having specific properties can solve the above problems, and completed the present invention. That is, the present invention is as follows.

[0009] One aspect of the present invention is a composite. The composite is a composite including a porous substrate, an aerogel filled in voids of the porous substrate, and a hot melt film covering at least a part of the surface of the porous substrate, wherein the hot melt film has a shrinkage rate of less than 10% when heated at 90°C for 1 minute.

[0010] In the composite of the above aspect, it is preferable that the porous substrate is a foam.

[0011] In the composite of the above aspect, it is preferable that the hot melt film is formed from one or more selected from polyolefin, polyester, and polyurethane.

[0012] In the composite of the above aspect, it is preferable that an adhesive is provided on at least a part of the surface of the hot melt film.

[0013] Another aspect of the present invention is a heat insulating material. The heat insulating material includes the composite of the above aspect.

Advantages of the Invention

[0014] According to the present invention, it is possible to suppress the shedding of aerogel particles and provide a composite and a heat insulating material having excellent adhesion to an adhesive.

Brief Description of the Drawings

[0015]

Figure 1

Modes for Carrying Out the Invention

[0016] Hereinafter, the composite and the heat insulating material according to the present invention will be described in detail.

[0017] The shapes of the composite and the heat insulating material can be appropriately shaped according to the application.

[0018] In the present invention, the density (apparent density) is the apparent density measured in accordance with JIS K7222:2005 "Foamed Plastics and Rubbers - Method for Determining Apparent Density".

[0019] In the present invention, the composite includes those in which a porous substrate is filled with an aerogel. However, the porous substrate before filling with the aerogel and the porous substrate after filling with the aerogel are treated as the same, and in some cases, the description of either one may be omitted or read as the description of the other.

[0020] In this specification, powder falling means that the particles of the aerogel fall off from the composite or the heat insulating material.

[0021] In this specification, a hot melt film means a film having a shrinkage rate (details will be described later) of less than 10% when heated at 90°C for 1 minute, and a shrink film means a film having a shrinkage rate of 10% or more.

[0022] 1. Composite FIG. 1 is a schematic cross-sectional view schematically showing the composite of the present embodiment. As shown in FIG. 1, the composite 100 of the present embodiment includes a porous substrate 10, an aerogel 20 filled in the voids of the porous substrate, and a hot melt film 30 covering at least a part of the surface of the porous substrate.

[0023] The filling rate (the ratio of the volume occupied by the filled aerogel in the bubbles) of the aerogel 20 occupying the individual bubbles (cells) contained in the porous substrate 10 is not particularly limited and can be 50% to 100%, more preferably 70% to 100%, and even more preferably 90% to 100%. When the filling rate of the aerogel is within such a range, it is possible to provide a heat insulating material having excellent heat insulating properties and excellent shape followability.

[0024] The thickness of the composite 100 is preferably 0.05 mm or more, 0.10 mm or more, 0.20 mm or more, 0.50 mm or more, 0.75 mm or more, 1.00 mm or more, etc., and also preferably 40.0 mm or less, 30.0 mm or less, 20.0 mm or less, 10.0 mm or less, 5.00 mm or less, 4.00 mm or less, 3.00 mm or less, 2.00 mm or less, etc.

[0025] Hereinafter, the aerogel 20, the porous substrate 10, and the hot melt film 30 constituting the composite 100 will be described in detail respectively.

[0026] 1-1. Aerogel The aerogel of the present embodiment is not particularly limited, and examples thereof include low-density dry gels. Specific examples include aerogels obtained by using a supercritical fluid drying method, xerogels by a normal drying process, cryogels by freeze drying, and the like.

[0027] 1-1-1. Components As the aerogel, any suitable aerogel component can be used. For example, it can be selected from 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. Among them, a silica aerogel containing silica (SiO2) can be preferably used.

[0028] 1-1-2. Structure / Physical properties / Properties 1-1-2-1. Pore diameter The pore diameter of the aerogel is preferably 70 nm or less, more preferably 60 nm or less, and even more preferably 50 nm or less. Here, the "pore diameter" is a value measured using a pore distribution measuring device (for example, BELSORP MINI manufactured by Microtrack Bell Co., Ltd.) in accordance with JIS Z8831-2 "Pore diameter distribution and pore characteristics of powders (solids) - Part 2: Measurement method of mesopores and macropores by gas adsorption". When in such a range, it is possible to provide a heat insulating material having excellent heat insulating properties and even more excellent shape followability.

[0029] 1-2. Porous substrate The porous substrate of this embodiment is not particularly limited, and examples include non-woven fabric, woven fabric, foam, etc. Among them, a foam is preferably used. In particular, a continuous cell resin foam having a continuous cell structure is more preferable. By using a continuous cell resin foam as the porous substrate, it becomes possible to sufficiently fill the aerogel inside the foam, and it becomes possible to provide a heat insulating material having excellent heat insulating properties and even more excellent shape followability. Hereinafter, taking the case where the porous substrate is a foam as an example, the components, thickness, structure, physical properties / properties, etc. of the porous substrate will be described.

[0030] 1-2-1. Components The resin component constituting the porous substrate is not particularly limited and can be a known resin component. For example, it preferably contains one or more resin components selected from the group consisting of olefin resins, acrylic resins, urethane resins, vinyl acetate resins, vinyl chloride resins, epoxy resins, rubbers, silicone resins, melamine resins, imide resins, etc.

[0031] 1-2-2. Thickness The thickness of the porous substrate can be 0.03 mm to 50.0 mm. This thickness is preferably 0.05 mm or more, 0.10 mm or more, 0.20 mm or more, 0.50 mm or more, 0.75 mm or more, 1.00 mm or more, etc., and is preferably 40.0 mm or less, 30.0 mm or less, 20.0 mm or less, 10.0 mm or less, 5.00 mm or less, 4.00 mm or less, 3.00 mm or less, 2.00 mm or less, etc.

[0032] 1-2-3. Structure (Closed-cell resin foam with skin) As described above, the porous substrate preferably has a closed-cell structure, and in particular, it is more preferably a closed-cell resin foam with skin (hereinafter may be simply abbreviated as 'resin foam') having a skin layer (not shown) and a foam layer having closed cells. Commercially available products can be used as the closed-cell resin foam with skin.

[0033] Note that the skin layer may be provided on one side or both sides. The presence of the skin layer can suppress the shedding (powdering) of the aerogel particles. Also, when coating the porous substrate with the hot melt film described later, the adhesion between the hot melt film and the porous substrate can be further improved, so that it is possible to provide a heat insulating material with more excellent heat insulating properties.

[0034] 1-2-3-1. Skin layer The skin layer is formed, for example, when a foamed composition is supplied onto a PET sheet or the like and shaped into a sheet or the like having a desired thickness of the resin foam by known means such as a doctor knife or a doctor roll, and the surface of the foam layer that comes into contact with the PET sheet and the coating tool such as the doctor knife is altered.

[0035] In addition, the skin layer can also be formed by producing a foam layer having open cells and then subjecting the foam layer having open cells to a heat treatment using a hot press machine or a hot roll machine.

[0036] Since the skin layer and the foam layer are integral, the open cells contained in the foam layer and the open cells contained in the skin layer communicate with each other, and the foam layer also has air permeability. That is, even the open cell resin foam with a skin layer has air permeability.

[0037] The skin layer contains open cells, including those that reach the surface of the skin layer. Therefore, the skin layer can permeate the outside air. That is, it has air permeability.

[0038] The open cells contained in the skin layer and the open cells contained in the foam layer are connected by communication through holes, and fluids such as outside air can flow back and forth between the open cells contained in the skin layer and the open cells contained in the foam layer.

[0039] Here, although the air permeability of the skin layer alone cannot be measured, it can be determined whether the skin layer has air permeability by measuring the air permeability of the open cell resin foam with a skin layer through the surface of the skin layer.

[0040] When the foam includes a skin layer, the thickness of the porous substrate indicates the sum of the thickness of the skin layer and the thickness of the foam layer.

[0041] The thickness of the skin layer is not particularly limited and can be, for example, 0.01 to 30 μm, more preferably 0.01 to 15 μm, and even more preferably 0.01 to 10 μm. When the thickness of the skin layer is within such a range, powder shedding can be more effectively suppressed.

[0042] 1-2-3-2. Average cell diameter (RB) of continuous bubbles The average cell diameter (RB) of the continuous bubbles in a cross-section perpendicular to the surface of the skin layer is not particularly limited, and can be, for example, 5 μm to 300 μm, preferably 5 μm to 200 μm, and more preferably 5 μm to 100 μm.

[0043] Furthermore, the size of the aerogel encapsulated in the continuous bubbles is restricted by the average cell diameter of the continuous bubbles, and the size of the aerogel also becomes the same size. When the average cell diameter is within such a range, it is possible to provide a heat insulating material with excellent heat insulation properties and excellent shape followability.

[0044] 1-2-4. Physical properties / characteristics 1-2-4-1. Air permeability The air permeability of the porous substrate is 0.01 cm 3 / cm 2 / sec or more, 0.5 cm 3 / cm 2 / sec or more, 10 cm 3 / cm 2 / sec or more, or 25 cm 3 / cm 2 / sec or more, etc. are preferable. Also, since the higher the upper limit of the air permeability, the better, it is not particularly limited. The upper limit of the air permeability of the porous substrate can be, for example, 300 cm 3 / cm 2 / sec or less. When the measured air permeability of the porous substrate is 0.01 cm 3 / cm 2 / sec or more, it is determined that the porous substrate has a certain degree of air permeability.

[0045] Particularly when it is 10 cm 3 / cm 2 / sec or more, in the sol solution filling process described later, it is not necessary to perform a time-consuming evacuation for the porous substrate, and an efficient manufacturing method can be achieved.

[0046] Such a ventilation rate can be measured by known methods and is not particularly limited. For example, it can be measured using the method described in JIS L1096-7:2010 "Textile and Knitted Fabric Test Methods: Method A (Frazee Method)".

[0047] 1-2-4-2. Density The density of the porous substrate is 0.020 g / cm 3 or more, 0.030 g / cm 3 or more, 0.040 g / cm 3 or more, 0.050 g / cm 3 or more, 0.075 g / cm 3 or more, 0.100 g / cm 3 or more, 0.120 g / cm 3 or more, etc. are preferable. Also, 0.275 g / cm 3 or less, 0.250 g / cm 3 or less, 0.240 g / cm 3 or less, 0.230 g / cm 3 or less, 0.220 g / cm 3 or less, 0.210 g / cm 3 or less, 0.200 g / cm 3 or less, etc. are preferable. By setting the density of the porous substrate within the above range, it is possible to obtain a composite material with excellent flexibility while controlling the filling amount of the aerogel so as to exhibit excellent heat insulation properties.

[0048] 1-2-4-3. Porosity The porosity of the porous substrate (resin foam) is calculated by dividing the apparent density of the resin foam after foaming by the density of the unfoamed raw material resin, subtracting this divisor from 1, and expressing it as a percentage.

[0049] The porosity is not particularly limited. For example, the porosity can be 50 - 99%, more preferably 65 - 99%, and even more preferably 85 - 99%. When the porosity is within such a range, it is possible to provide a heat insulating material with excellent heat insulation properties and even better shape followability. Note that the preferred porosity values here are the preferred values for open-cell resin foams, regardless of whether they have a skin or not.

[0050] 1-3. Hot Melt Film As described above, the hot melt film of this embodiment covers at least a part of the surface of the porous base material filled with aerogel in the voids. By covering the porous base material with the hot melt film, the detachment of aerogel particles can be suppressed.

[0051] In this embodiment, the entire surface of the porous base material may be covered with the hot melt film, or only a part (for example, one side) of the porous base material may be covered. FIG. 1 shows an example in which only one side of the porous base material is covered with the hot melt film. Considering that the detachment of aerogel particles can be more suppressed, it is preferable to cover the entire surface of the porous base material with the hot melt film.

[0052] 1-3-1. Softening Point The hot melt film is a resin film mainly composed of a thermoplastic resin that softens at a certain temperature. The softening point of the hot melt film is preferably 60 ° C or higher, 80 ° C or higher, 90 ° C or higher, etc., and preferably 125 ° C or lower, 120 ° C or lower, 115 ° C or lower, etc. When the softening point of the hot melt film is within such a range, when covering the porous base material with the hot melt film, by heat lamination, the hot melt film softens, so that the adhesion with the porous base material can be made stronger. Further, by heating to the above temperature, the hot melt film softens, so that the portion to be covered with the porous base material can be surely covered with the hot melt film.

[0053] The method for measuring the softening point can be carried out by a known method and is not particularly limited. As a method for measuring the softening point, for example, it can be measured by a method according to JIS K6863-1994 "Test Method for Softening Point of Hot Melt Adhesives".

[0054] 1-3-2. Shrinkage Rate The hot melt film has a shrinkage rate of less than 10% when heated at 90°C for 1 minute, preferably 8% or less, and more preferably 5% or less. By setting the shrinkage rate within the above range, when coating the hot melt film with a porous substrate, the hot melt film is less likely to shrink even when heat laminated. As a result, when an adhesive is provided on a part of the surface of the hot melt film, the adhesion between the hot melt film and the adhesive can be made stronger.

[0055] As a method for measuring the shrinkage rate, first, a hot melt film cut into 50 mm × 50 mm is heated at 90°C for 1 minute, and then the lengths in the vertical and horizontal directions are measured. For each of the vertical and horizontal directions, the ratio of the shrunk length after heating to the length before heating is calculated. The same operation is performed three times, and the average value of a total of six values including the vertical and horizontal directions is taken as the shrinkage rate.

[0056] 1-3-3. Elongation and contraction rate The hot melt film preferably has an elongation and contraction rate (elongation) of 200% or more, 300% or more, 400% or more, 500% or more, 600% or more, etc. By setting the elongation and contraction rate of the hot melt film within the above range, when applying a heat insulating material including a composite to a curved portion, cracks or the like do not occur on the surface, and better followability can be exhibited with respect to the curved portion.

[0057] The method for measuring the elongation and contraction rate (elongation) can be performed by a known method and is not particularly limited. As a method for measuring the elongation and contraction rate (elongation), for example, it can be measured by a method according to JIS K6251:2017 "Vulcanized Rubber and Thermoplastic Rubber - Method for Determining Tensile Properties".

[0058] 1-3-4. Material As the material of the hot melt film, those having the above-described properties can be used. For example, polyethylene such as ethylene-vinyl acetate copolymer (EVA) resin, ethylene-acrylic acid copolymer (EAA) resin, ethylene-methyl acrylate copolymer (EMA) resin, ethylene-methyl methacrylate copolymer (EMMA) resin, and copolymer of ethylene and methacrylic acid (EMAA); polyolefins such as polypropylene and polyethylene; styrene-based synthetic rubbers such as styrene-isoprene block copolymer (SI) rubber, styrene-isoprene-styrene block copolymer (SIS) rubber, and polystyrene-polybutadiene block copolymer resin; polyamide (nylon) resin; polyester such as polyethylene terephthalate; polyurethane such as thermoplastic polyurethane (TPU). These can be used alone or as a mixture, copolymer, or polymer alloy of a plurality of them. Among these, a hot melt film formed from one or more selected from polyolefins, polyesters, and polyurethanes is preferred.

[0059] 1-3-5. Thickness The thickness of the hot melt film is preferably 3 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 20 μm to 80 μm. When the thickness of the hot melt film is within such a range, it can efficiently coat the porous base material without inhibiting the heat insulation property. Here, the thickness of the hot melt film is defined as the average value obtained by selecting 10 arbitrary points on the hot melt film and measuring the thickness.

[0060] 1-4. Others The composite of the present embodiment may contain an adhesive or the like between the above-described respective components or on at least a part of the surface of the hot melt film. The adhesive is not particularly limited, and various known adhesives are used. For example, thermosetting type and ultraviolet curable type adhesives are exemplified. More specifically, adhesives such as rubber-based, acrylic-based, urethane-based, silicone-based, and polyvinyl ether can be mentioned.

[0061] 2. Heat Insulating Material The heat insulating material of this embodiment includes the composite described above. Hereinafter, the physical properties / characteristics of the heat insulating material will be described.

[0062] 2-1. Peel strength When using a composite provided with an adhesive on at least a part of the surface of a hot melt film as the heat insulating material of this embodiment, it is preferable that the peel strength is 3.0 N / 10 mm or more, 3.5 N / 10 mm or more, 4.0 N / 10 mm or more, etc. By setting the peel strength within the above range, for example, even when applied to a curved portion such as a pipe, the heat insulating material is difficult to peel off and can be appropriately used. The measurement method of the peel strength will be described in detail in the examples described later.

[0063] 2-2. Thickness The thickness of the heat insulating material is preferably 0.10 mm or more, 0.20 mm or more, 0.50 mm or more, 0.75 mm or more, 1.00 mm or more, 2.00 mm or more, etc., and is preferably 100.0 mm or less, 80.0 mm or less, 50.0 mm or less, 40.0 mm or less, 30.00 mm or less, 25.00 mm or less, 20.00 mm or less, etc.

[0064] 3. Manufacturing method of the heat insulating material (composite) The heat insulating material (composite) can be manufactured as follows. Here, an example in which the porous base material is the above-mentioned continuous cell resin foam with skin will be described.

[0065] The manufacturing method of the heat insulating material includes a porous base material forming step of forming a porous base material (continuous cell resin foam with skin), a sol solution filling step of filling the porous base material with a sol solution which is a raw material of aerogel under normal pressure or reduced pressure, a gelation step of gelling the filled sol solution, and a drying step of drying the wet gel. Each step will be described in detail below. Also, as the manufacturing method of the heat insulating material (composite material), steps (steps) other than the steps described below can be further included.

[0066] 3-1. Porous base material forming step The following describes the porous base material forming step in detail. When the porous base material exhibits the effects of the present invention, a commercially available closed-cell resin foam with a skin may also be used. Therefore, in the manufacturing method of the heat insulating material (composite), the porous base material forming step is not necessarily included.

[0067] The porous base material forming step includes a porous material forming step and a hot compression step. As the porous base material forming step, the case of using a melamine resin as a raw material will be exemplified below, but the present invention is not limited thereto.

[0068] 3-1-1. Porous Material Forming Step The porous material forming step is not particularly limited as long as it can form a melamine foam which is a porous material, and can be carried out based on a general method for manufacturing a melamine foam.

[0069] The melamine foam can be prepared by blending a foaming agent, a catalyst, an emulsifier, etc. with melamine and formaldehyde or their precondensates which are the main raw materials, mixing them, then injecting them into a mold, and heating or irradiating with electromagnetic waves, etc., to generate heat in the foaming raw materials, and causing foaming and curing.

[0070] The molar ratio of melamine to formaldehyde for generating the precondensate is preferably melamine:formaldehyde = 1:1.5 to 4.0, particularly 1:2 to 3.5. Also, a precondensate having a number average molecular weight of 200 to 1000, particularly 200 to 400, is preferred. Note that as formaldehyde, formalin which is usually an aqueous solution thereof is used.

[0071] As monomers for generating the precondensate, in addition to melamine and formaldehyde, when these monomers are 100 parts by mass (hereinafter abbreviated as parts), various monomers of 50 parts or less, particularly 20 parts or less, can be used.

[0072] As other monomers corresponding to melamine, alkyl-substituted melamine, urea, urethane, carboxylic acid amide, dicyandiamide, guanidine, sulfuryl amide, sulfonic acid amide, aliphatic amine, phenol and its derivatives, etc. can be used. Further, as aldehydes, acetaldehyde, trimethylol acetaldehyde, acrolein, benzaldehyde, furfural, glyoxal, phthalaldehyde, terephthalaldehyde, etc. can be used.

[0073] Also, as the foaming agent, pentane, trichlorofluoromethane, trichlorotrifluoroethane, etc. can be used.

[0074] As the catalyst, formic acid is usually used, and as the emulsifier, anionic surfactants such as sodium sulfonate can be used.

[0075] The electromagnetic wave irradiated to promote the curing reaction of the foaming raw material is preferably adjusted so that its power consumption is 500 to 1000 kW, particularly 600 to 800 kW, with respect to the foaming raw material.

[0076] The thickness and density of the melamine foam may be appropriately set according to the conditions of the hot compression step and the thickness and density of the desired porous base material.

[0077] Here, for the melamine foam, it is also possible to leave unreacted methylol groups and react the methylol groups in the subsequent hot compression step.

[0078] The obtained melamine foam may be processed into a predetermined size.

[0079] 3-1-2. Hot Compression Step In the hot compression step, the porous material (melamine foam) obtained by the porous material forming step is hot compressed and plastically deformed to obtain a porous base material having a predetermined density and air permeability. That is, the porous base material refers to the state after compressing the porous material (melamine foam).

[0080] The hot compression step can be carried out, for example, by a method of heating and compressing between the hot plates of a compression molding machine. At this time, the temperature of the hot plate (press temperature) is preferably 100 to 250 ° C, more preferably 120 to 200 ° C, and still more preferably 150 to 180 ° C. In particular, as a method for preventing restoration described later, when impregnating with a curing agent, the press temperature may be near the curing temperature of the curing agent, preferably ± 10 ° C of the curing temperature of the curing agent. By setting the press temperature within such a range, while sufficiently plastically deforming the porous base material, the shape of each air bubble can be made desirable, and it is easy to make the air permeability etc. of the obtained porous base material within a desired range. Note that the time and load of the hot compression may be adjusted so as to obtain a porous base material having a desired thickness.

[0081] In addition, in the hot compression step, it is preferable to carry out hot compression so that the thickness of the porous base material / the thickness of the porous material is 1 / 2 to 1 / 15, or 1 / 3 to 1 / 10. By setting such a range, the cells of the porous base material become dense by hot compression molding, the dropout of the aerogel can be suppressed, and it is also possible to impart flexibility to the composite.

[0082] Here, when plastically deforming the porous base material by hot compression, if it is only hot compression, when the compression load is removed, a restoring force may act on the porous foam base material. Therefore, it is preferable to additionally adopt a method (restoration prevention method) for maintaining the state in which the porous base material is hot compressed.

[0083] Examples of the restoration prevention method include the method described above in which the porous material is made to contain unreacted methylol groups and the methylol groups are reacted in the hot compression step.

[0084] The unreacted methylol groups contained in the porous material can be confirmed by measuring the absorption spectrum with a Fourier transform infrared spectrometer (FT-IR), and 1000 to 1100 cm -1The content of the methylol group can be estimated from the peak intensity of the absorption spectrum in the vicinity. Also, in the porous base material obtained by thermally compressing the porous material, unreacted methylol groups remain, and the content of the methylol group can be estimated by the same method.

[0085] Also, as another method for preventing restoration, there is a method in which a hardener impregnation step of previously impregnating the porous material before the hot compression step with a hardener is provided, and the hardener is thermally cured by the hot compression step. A plurality of types and / or a plurality of times of methods for preventing restoration may be implemented. In particular, when the porous material is a melamine foam, it is preferable to perform the hardener impregnation step.

[0086] The hardener in the hardener impregnation step is not particularly limited as long as the hardener in the resin is activated and cured by heating. Examples thereof include melamine resin, epoxy resin, and phenol resin.

[0087] In the hardener impregnation step, the amount of the hardener impregnated into the porous material is preferably 0.5 to 10.0 parts by mass, more preferably 1.0 to 5.0 parts by mass, when the porous material is 100 parts by mass. By setting such a range, it is possible to achieve both sufficient flexibility and heat insulation properties and shape maintainability after the hot compression step.

[0088] The obtained porous base material (continuous cell resin foam with skin) can be processed into a predetermined size. Bubbles with a continuous cell structure are exposed on the cut surface. The sol solution is filled from these exposed bubbles.

[0089] Through the above porous base material forming step, a porous base material, that is, a continuous cell resin foam with a skin layer having continuous cells is obtained.

[0090] 3-2. Sol solution filling step Hereinafter, silica aerogel, which is a preferred example of aerogel, will be described in detail as an example, but the present invention is not limited to silica aerogel only.

[0091] 3-2-1 Sol Solution As a silicone raw material for silica aerogel, a silicone alkoxide or its derivative or an alkali metal silicate can be used, and it is mixed with an aqueous solvent to form a sol solution.

[0092] The silicone raw material is not particularly limited as long as the effects of the present invention are achieved. Examples of the silicone alkoxide and its derivatives include tetramethoxysilane, tetraethoxysilane, tetramethoxysilane oligomer, tetraethoxysilane oligomer, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, hexyltrimethoxysilane, monohexyltriethoxysilane, etc. Examples of the alkali metal silicate include potassium silicate and sodium silicate. The silicone raw materials can be used in combination of a plurality. When a plurality are used, the combination and blending ratio can be selected according to the purpose.

[0093] For the hydrolysis of the silicone raw material, it is preferable to use water and a solvent that is compatible with water and dissolves the silicone raw material. Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic diols such as ethanediol, propanediol, butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; aromatic diols or alicyclic diols such as hydrogenated bisphenol A, bisphenol A, and cyclohexanediol; polyhydric alcohols such as glycerin, diglycerin, trimethylolpropane, trishydroxymethylaminopentane, pentaerythritol, dipentaerythritol, and hexamethylolmelamine; hexane, toluene, chloroform, diethyl ether, tetrahydrofuran, ethyl acetate, acetone, and acetonitrile. These solvents may be used alone or in combination of two or more.

[0094] In order to efficiently hydrolyze the silicone raw material, it is preferable to add a catalyst to the reaction system in advance. The catalyst is not particularly limited. For example, as acidic catalysts, formic acid, acetic acid, succinic acid, malic acid, citric acid, hydrochloric acid, nitric acid, boric acid, sulfuric acid, carbonic acid, phosphoric acid, etc. are included. As basic catalysts, metal oxides and / or hydroxides such as sodium hydroxide and potassium hydroxide, aliphatic and / or aromatic amines such as dimethylamine, triethylamine, N,N-dimethylbenzylamine, aniline, 1,5-naphthalenediamine, ammonia, naphthenic acid of divalent metals, hydroxides of divalent metals, etc. can be mentioned. These catalysts may be used alone or in combination of two or more.

[0095] 3-2-2. Filling method The filling method of the sol solution is not particularly limited as long as it is carried out under normal pressure or reduced pressure, and known methods can be used. For example, a method of filling by completely impregnating the continuous cellular resin foam with skin obtained by the above-described method into the prepared sol solution under reduced pressure can be mentioned. In particular, when the air permeability is 10 cm 3 / cm 2 / sec or more, filling under normal pressure is possible.

[0096] Specifically, taking a sol solution obtained by mixing tetramethoxysilane (hereinafter referred to as TMOS): methanol: water: catalyst (ammonia) in a molar ratio of 1:7.2:4:0.01 as an example, a resin foam is placed in a separable flask, and the sol solution is gradually introduced to immerse the resin foam completely in the sol solution, and the sol solution can be filled into the resin foam. Leave it as it is for 2 to 3 hours until gelation.

[0097] Reactive functional groups such as unreacted hydroxyl groups, carboxyl groups, and amino groups remaining in the continuous bubble resin foam may react with the hydrophobizing agent described later. If a large amount of reactive functional groups are present, it may inhibit the hydrophobization reaction of the wet gel. Therefore, the reactive functional groups remaining in the continuous bubble resin foam may be inactivated in the previous step of the sol solution filling step. The method for inactivating the reactive functional groups is not particularly limited, and known methods can be used.

[0098] 3-3. Gelation step The sol solution filled in the resin foam undergoes a sol-gel reaction, where TMOS is hydrolyzed by water and a catalyst, passes through a sol state, and forms a wet gel. Here, the wet gel refers to a solid that remains in a solid state while containing a liquid such as the residual liquid of the sol solution after gelation.

[0099] A wet gel is formed inside the continuous bubbles in the foam by the sol-gel reaction due to the hydrolysis of silicone alkoxide or its derivative.

[0100] After forming the wet gel, a step of removing water and unreacted substances in the wet gel may be included. Solvents used in this step include, for example, alcohols such as methanol, ethanol, isopropanol, and butanol, and acetone, acetonitrile, etc. The foam filled with the wet gel is immersed in the solvent, and the solvent is replaced with a new one several times to complete the step.

[0101] The step of hydrophobizing the OH groups on the surface of the silica aerogel may be included by using a hydrophobizing agent having a functional group reactive with the hydrophilic silanol group and a hydrophobic group. As the hydrophobizing agent, one having a functional group reactive with the silanol group and a hydrophobic group is used. Examples of the functional group reactive with the silanol group include halogen, amino group, imino group, carboxyl group, alkoxyl group, and hydroxyl group. Examples of the hydrophobic group include alkyl group, phenyl group, and their fluorides. The hydrophobizing agent may have only one kind of each of the above functional group and hydrophobic group, or may have two or more kinds. For example, organic silane compounds such as hexamethyldisilazane, hexamethyldisiloxane, trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane, triethylmethoxysilane, dimethyldichlorosilane, dimethyldiethoxysilane, methyltrichlorosilane, and ethyltrichlorosilane can be mentioned. In addition to these, organic compounds such as carboxylic acids such as acetic acid, formic acid, and succinic acid, and alkyl halides such as methyl chloride can be mentioned. Only one kind of hydrophobizing agent may be used, or two or more kinds may be used.

[0102] In order to improve the adhesion between the aerogel and the continuous resin foam and suppress the detachment of the aerogel, a coupling agent may be added. The coupling agent is not particularly limited as long as it can react with both the silanol groups on the surface of the aerogel and the reactive functional groups such as hydroxyl groups, carboxyl groups, and amino groups remaining in the continuous resin foam, and any suitable coupling agent can be used. It is preferable to use a silane coupling agent as the coupling agent. For example, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, tris-(trimethoxysilylpropyl) isocyanurate, etc. can be mentioned.

[0103] 3-4. Drying process In the drying process, the wet gel is dried. A known method can be used as the drying method and is not particularly limited. When drying the wet gel, supercritical fluid drying is preferable because silica aerogel is difficult to break. Examples of supercritical fluid drying include a method of removing all of the solvent while substituting it with carbon dioxide having a lower critical point than this solvent under conditions of about 80°C and 20 MPa.

[0104] 3-5. Coating process In the coating process, the surface of the porous substrate impregnated with the aerogel is coated with the above-mentioned hot melt film to form a composite. As a method of coating the porous substrate with the hot melt film, the heat lamination method is preferable. The heat lamination method is a method of heating an iron to a predetermined temperature and pressing and coating the porous substrate and the hot melt film.

[0105] In the heat lamination method, the heating temperature is preferably the melting point of the hot melt film + 20°C, and can be, for example, in the range of 180°C to 200°C, 120°C to 150°C, etc. By heating at a temperature in this range, the hot melt film softens moderately and can coat the porous substrate.

[0106] An adhesive such as a double-sided tape may be attached to at least a part of the hot melt film of the composite obtained in the coating step.

Examples

[0107] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the embodiments below.

[0108] ≪Examples and Comparative Examples≫ Using the method shown below, a porous substrate filled with aerogel was coated with a coating material of the material shown in Table 1 below to create composites for each example and comparative example.

[0109] <Manufacture of Porous Substrate> (Porous Material) Melamine foam having unreacted methylol groups, density 0.014 g / cm 3

[0110] A melamine foam having unreacted methylol groups with a thickness of 10.0 mm was used as the porous material, and at a press temperature of 160°C, the porous material was hot-compressed between the hot plates of a compression molding machine so as to have a thickness of 1.7 mm, and a hot-formed porous substrate (melamine foam with skin) (50 mm × 25 mm × t1.7 mm) was obtained.

[0111] <Manufacture of Composite> (Raw Materials of Silica Aerogel) ·Silicone raw material 4-functional ethoxysilane oligomer (average pentamer) (Solvent) ·Ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ·Ion-exchanged water, electrical resistivity 1 × 1010 Ω·cm or more Catalyst 25% aqueous ammonia solution (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0112] (Sol solution filling step) Using a silicone raw material as the main agent, 53 mol of ethanol, 21 mol of ion-exchanged water, and 0.01 mol of catalyst were mixed with 1 mol of the main agent to form a sol solution. The above-mentioned porous substrate (melamine foam with skin) was cut into a size that could be stored in a separable flask with the skin layer attached and stored. The prepared sol solution was added until the melamine foam with skin was completely immersed, and it was left standing for 3 hours under normal pressure to obtain a melamine foam with skin filled with a wet gel.

[0113] The obtained melamine foam with skin filled with the wet gel was immersed in ethanol, and ethanol was repeatedly exchanged while stirring, and solvent substitution was carried out for 24 hours. Next, in order to hydrophobize the gel surface, it was immersed in an ethanol solution (concentration 15% by mass) of hexamethyldisilazane to which 0.1 mol% of an aqueous hydrochloric acid solution was added as a catalyst, and the hydrophobization treatment was carried out for 24 hours while stirring.

[0114] (Drying step) The melamine foam with skin whose gel surface was hydrophobized was impregnated in carbon dioxide at 80 °C and 20 MPa, and supercritical fluid drying was carried out for 12 hours.

[0115] As described above, a melamine foam with skin (porous substrate) filled with silica aerogel inside was obtained.

[0116] (Coating step) For each of Examples 1 to 3 and Comparative Examples 1 and 2, the coating material shown in Table 1 below was laminated on the surface of the obtained porous substrate (50 mm × 25 mm × t1.7 mm), and heat lamination was carried out by pressing with an iron under the conditions of a temperature of 200 °C and a time of 5 seconds, and the entire surface of the porous substrate was coated with the coating material. For Comparative Example 3, except that no coating material was used, it was the same as the other examples and comparative examples, and samples of composites of each example and comparative example were prepared.

[0117] As shown in Table 1 below, as the coating material, hot melt film was used in Examples 1 to 3, and shrink film was used in Comparative Examples 1 and 2. The hot melt film had a shrinkage rate of less than 10% as described above, and the shrink film had a shrinkage rate of 10% or more. For the coating materials used in each of Examples 1 to 3 and Comparative Example 1, those with dimensions of 60 mm × 35 mm × (thickness described in Table 1 below) were used.

[0118] <Evaluation and Observation> For the samples of the composites of each example and comparative example, after attaching a double-sided tape (501L, manufactured by Nitto Denko Corporation) as an adhesive to the surface of the hot melt film, the peel strength was measured. Also, the presence or absence of the dropout of aerogel particles was observed.

[0119] (Peel Test) A 180° peel test was conducted using a material testing machine (Autograph AG-X, manufactured by Shimadzu Corporation). Specifically, a 10-mm portion from the end of the sample was fixed to the chuck part of the material testing machine, and the sample was peeled at a tensile speed (crosshead speed) of 300 mm / min to measure the peel strength.

[0120] (Evaluation Criteria) A: The peel strength is 4.0 N / 10 mm or more B: The peel strength is 3.0 N / 10 mm or more and less than 4.0 N / 10 mm C: The peel strength is less than 3.0 N / 10 mm

[0121] (Observation of the Presence or Absence of Dropout of Aerogel Particles) During the above-described peel test, that is, in the process from attaching the double-sided tape to the samples of the composites of each example and comparative example until installing the sample on the material testing machine, the presence or absence of dropout (powder fall) of the surrounding aerogel particles was visually confirmed. (Evaluation Criteria) A: No powder fall B: Powder fall

[0122]

Table 1

Industrial Applicability

[0123] The composite and the heat insulating material of the present invention can suppress the shedding of aerogel particles and are excellent in adhesion to an adhesive, and thus can be used as a heat insulating material for electronic components such as home appliances and mobile devices.

Explanation of Reference Numerals

[0124] 10 Porous substrate 20 Aerogel 30 Hot melt film 100 Composite (heat insulating material)

Claims

1. A porous substrate, an aerogel filled in the pores of the porous substrate, and a hot melt film covering at least a part of the surface of the porous substrate, wherein the composite includes: the hot melt film has a shrinkage rate of less than 10% when heated at 90°C for 1 minute.

2. The composite according to Claim 1, wherein the porous substrate is a foam.

3. The composite according to Claim 1 or 2, wherein the hot melt film is formed from one or more selected from polyolefin, polyester, and polyurethane.

4. The composite according to Claim 1 or 2, wherein an adhesive is provided on at least a part of the surface of the hot melt film.

5. A heat insulating material comprising the composite according to Claim 1 or 2.

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