JP2010047710A - Foamed polymer-silica composite having flexibility and moldability, and heat insulation material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamed polymer-silica composite having high heat insulation properties sustainable over a long period, flexibility, and moldability together and suitably applicable to a heat insulation material, and to provide a method for producing the same. <P>SOLUTION: The foamed polymer-silica composite having flexibility and moldability includes a foamed polymer structure and porous silica gel with density of 0.23 g/cm<SP>3</SP>or less. The inside wall of porous cells in the foamed polymer structure is coated with the porous silica gel while leaving cavities inside. In the method for producing the foamed polymer-silica composite, a sol-gel reaction based on the hydrolysis of silicon alkoxide or its derivative is performed on the inner surfaces of foamed cells in the foamed polymer structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a foamed polymer-silica composite coated with a low-density porous silica gel so that the inner surface of the foamed polymer structure is coated and the foamed polymer structure is not completely filled and has voids therein. The present invention relates to a body, a manufacturing method thereof, and a heat insulating material using the body.

  Foamed polymers such as rigid urethane foams have been widely used as lightweight and inexpensive heat insulating materials, especially for building materials, because they exhibit high heat insulating performance by using high heat insulating gases such as chlorofluorocarbons as the foaming gas. It was. However, in recent years, the development of alternative materials has progressed due to the destruction of the ozone layer by foaming gas and the adverse effect on the global warming effect. Development of foam materials using alternative foaming gases such as carbon dioxide and hexane has been underway so far, but problems with thermal insulation performance and production process safety have been pointed out, and the current situation has not yet become widespread. .

  In the foamed polymer heat insulating material, the molecular weight of the foamed gas sealed inside is large, and the mean free path is small, so that heat transfer by convective heat transfer is small. However, since the foaming gas gradually diffuses to the outside and is replaced with the atmosphere, there is a big problem that the heat insulation performance deteriorates over time. A foamed polymer heat insulating material prepared by using carbon dioxide, nitrogen, hexane, or the like as an alternative foaming gas has a problem that heat insulation performance is low because the molecule is light and heat transfer by convection is large.

  The present inventors have so far developed a material in which a foamed polymer foam cell is filled with low-density silica gel, preferably silica airgel, to overcome the drawbacks of these foamed polymer-based heat insulating materials. (Patent Document 1). Silica aerogel is a generic name for low-density, ultra-porous silica, and is known for its excellent heat insulation performance (monolithic, atmospheric pressure, thermal conductivity around 0.012 to 0.02 W / mK near room temperature). ing. The thermal insulation performance of low-density silica gel and silica aerogel is such that the average pore diameter of the gel is suppressed to several tens of nanometers or less, which is lower than the mean free path of the main gas molecules such as nitrogen and oxygen. This is due to low heat. Further, since the silica skeleton has a low density, there is little conduction heat transfer. Since the heat insulation performance of these materials depends on the microstructure, the heat insulation performance is maintained as long as the structure does not break down, and aged deterioration unlike the foamed polymer heat insulation does not occur.

  On the other hand, low density silica and silica aerogel are extremely brittle solids having extremely low mechanical strength due to their low density, and lacking flexibility and moldability. In particular, a monolithic gel body having an excellent heat insulating effect is difficult to handle. On the other hand, the present inventors have shown so far that by combining with a polymer, a heat insulating material having both high heat insulating properties, flexibility and good handling properties can be obtained (Patent Documents 1 and 2). However, a special heat insulating material that covers a pipe having a complicated shape may require more flexibility and formability than those required for a general heat insulating material.

  On the other hand, apart from the study by the present inventors, recently, preparation of a composite in which silica airgel is combined with a continuous pore polymer foam has been reported (Patent Document 3). This document suggests that the mechanical strength of silica airgel is improved by compounding, and is more flexible than airgel and has high heat insulation properties. However, since this composite has a structure in which silica is continuous over the entire composite, the structure and physical properties of silica airgel are dominant, and the flexibility and moldability are insufficient.

JP 2007-332242 A Japanese Patent Application No. 2006-220906 International Publication WO2007 / 146945 A2 Publication

  An object of the present invention is to provide a heat insulating material having high heat insulating performance, flexibility and moldability, and maintaining the heat insulating performance for a long period of time, a foamed polymer-silica composite suitable for the heat insulating material, and a method for producing the same. It is in.

  The inventors of the present invention have repeatedly studied to achieve the above object. As a result, heat insulation performance and flexibility are achieved by preparing a composite with voids inside, which covers the inner surface of the foamed polymer cell with low-density silica and does not completely fill the foamed cell structure. The inventors have found that a material having moldability can be obtained, and have completed the present invention.

[1] That is, the present invention relates to a foamed polymer structure, and a porous silica gel having a density of 0.23 g / cm ³ or less coated on the inner wall of the foamed cell of the foamed polymer structure so as to have voids therein. And a foamed polymer-silica composite having flexibility and moldability.

[2] Further, the present invention provides the foamed polymer-silica composite according to the item [1], wherein the porous silica gel is an airgel having a density of 0.1 to 0.2 g / cm ³ or less. .

[3] Further, the present invention provides the foamed polymer-silica composite as described in [1] or [2], wherein the foamed polymer structure has a porosity of 90% or more and 99.9% or less. is there.

[4] The present invention provides the foamed polymer-silica composite according to any one of [1] to [3], wherein the foamed polymer structure includes polyurethane foam or a composite thereof. is there.

[5] The foamed polymer-silica composite according to any one of [1] to [3], wherein the foamed polymer structure includes melamine foam or a composite thereof. is there.

[6] In addition, the present invention includes the step of performing a sol-gel reaction by hydrolysis of silicon alkoxide or a derivative thereof on the inner surface of the foamed cell of the foamed polymer structure. It is a manufacturing method of the foaming polymer-silica composite body of any one.

[7] Further, the present invention is a method in which a foamed polymer structure is immersed in a sol-gel solution of silicon alkoxide or a derivative thereof to perform a sol-gel reaction by hydrolysis of the silicon alkoxide or a derivative thereof. Before gelling, the foamed polymer structure is removed from the sol-gel solution to form silica gel voids inside the foamed cells of the foamed polymer structure, [1] to [1], 5]. The method for producing a foamed polymer-silica composite according to any one of [5].

[8] Further, the present invention uses the foamed polymer-silica composite according to any one of [1] to [5], and has a thermal conductivity of 101 kPa at 20 ° C. of 0.03 W / mK or less. It is a heat insulating material having flexibility and moldability.

[9] Further, according to the present invention, when a compressive stress is applied to the material and the material is compressed by 40% in the direction in which the compressive stress is applied, the integrity is not impaired, and a heat of not more than 0.03 W / mK at 101 kPa and 20 ° C. The heat insulating material having flexibility and moldability according to the item [8], wherein the conductivity is maintained.

  According to the foamed polymer-silica composite of the present invention, it is possible to provide a heat insulating material having both high heat insulating properties, moldability, and flexibility, and having little deterioration over time in heat insulating performance. The heat insulating material of the present invention has a property and flexibility that does not change the heat insulating performance even when stress is applied in addition to heat insulating materials for residential and architectural use, so as a heat insulating material that covers piping having a complicated shape. Useful.

  Embodiments of the present invention will be described below.

  The foamed polymer structure used in the foamed polymer-silica composite according to the present invention has a foamed cell structure or a continuous network-like continuous structure obtained by removing the foamed wall, and is a flexible integral foam. If it is a body, it will not specifically limit. An open pore type (open cell type) foamed polymer is more suitable for introducing a silica component therein. The chemical species of the foamed polymer structure is not particularly limited, but a polyurethane foam having a polyether or polyester structure in terms of affinity with the silica component is a melamine foam in terms of the mechanical properties and chemical stability of the polymer. Is preferred. The polyurethane foam and melamine foam may be composites thereof.

  The porosity of the foamed polymer structure in the present invention is not particularly limited, but when the porosity is low, the effect of generating voids in the silica to be filled becomes unclear. Moreover, since the influence of the heat conduction of a polymer part becomes large, the performance as a heat insulating material falls. On the other hand, even in a polymer foam having an extremely high porosity such as a rough mesh, it is difficult to generate voids inside. The porosity of the polymer structure is preferably 90% or more and 99.9% or less, and more preferably 90% to 99% or less. The porosity of the foamed polymer structure is a ratio represented by the formula (1-density of foamed polymer structure / (skeleton or true) density of the polymer).

In the present invention, the foaming density of the foamed polymer structure and the average diameter of the foamed cells are preferably higher from the viewpoint of strength and physical properties of the foamed polymer structure. Causes difficulties in filling and creating voids. The average diameter of the foam cell is preferably about 100 to 1000 μm. The foam density is preferably 500 to 10 ⁶ pieces / cm ³ .

The porous silica gel in the foamed polymer-silica composite according to the present invention has a density of 0.23 g / cm ³ or less, which is about 10% or less of dense silica, and is particularly low-density silica having low heat transfer properties. It is not limited. The porosity of the porous silica gel is preferably 90% or more. From the viewpoint of heat insulation performance, it is more preferable that the density is 0.1 to 0.2 g / cm ³ and the average pore diameter is 60 nm or less which is lower than the average free path of air. Silica airgel having such density and structure is particularly preferable as the low density silica in the present invention.
In addition, the density (apparent density) of the porous silica gel in the foamed polymer-silica composite of the present invention is the production of the foamed polymer-silica composite except that the foamed polymer structure is not used when direct measurement is difficult. A sample of only silica gel is prepared under the same conditions as in 1. The density is defined as the density of porous silica gel.

The porous silica gel in the present invention is one in which the inner wall of the foamed cell of the foamed polymer structure is coated with a void inside. The thickness of the coating layer of silica gel is not particularly limited, but is preferably 10 to 40% of the foam cell inner diameter. Further, the silica content in the foamed polymer-silica composite is preferably 50 to 99% by mass.
The porosity P (hereinafter referred to as composite porosity) of the foamed polymer-silica composite after the porous silica gel is contained (coated) in the foamed cell of the foamed polymer in this way is the foamed polymer obtained by the composite. Assuming that the volume change is negligible, ρ is the density of the composite, ρ _{dp is} the density of the dense polymer that is the skeleton of the foamed polymer structure, ρ _{SiO2 is} the density of the dense silica, and the porosity of the foamed polymer structure is _Is defined by the following formula 1.
P = (ρ _dp · (1−P _pp ) + ρ _{SiO 2} · P _pp −ρ) / ρ _{SiO 2} (Formula 1)
Here, ρ is obtained by measuring volume and weight by a conventional method. ρ _dp and ρ _SiO2 can be determined using known data for each material used.
The composite porosity is not particularly limited because it is affected by the porosity of the porous silica gel and the void inside the foamed cell, but is preferably 85% or more and 99% or less, and more preferably 90% or more and 98% or less. preferable.

  The production method of the foamed polymer-silica composite in the present invention is not limited to this, but preferably (1) the existing polymer foam is impregnated with a precursor of low density silica to be gelled, It has a manufacturing process roughly divided into a process of coating the surface with a wet gel, and (2) a process of drying the coated wet gel to form a low density silica gel.

  As a method for preparing a wet gel having a low-density silica structure in the step (1), a solution process such as silicate hydrolysis and a sol-gel method using silicon alkoxides as a main raw material is preferably used. In the present invention, it is preferable to perform a sol-gel reaction by hydrolysis of silicon alkoxide or a derivative thereof on the inner surface of the foamed cell of the foamed polymer structure. The present invention is characterized by a structure that does not completely fill the pores of the polymer foam, but in order to obtain this structure, it is desirable that the gelation time is fast, and the gelation time can be controlled depending on the type and addition amount of the catalyst. It is particularly preferred that the sol-gel process proceeds on the inner surface of the polymer foam. The “sol-gel method” or “sol-gel reaction” refers to a method or reaction for producing metal oxide fine particles or gel by hydrolysis of a metal alkoxide, which is an inorganic precursor, and subsequent condensation polymerization. The “sol-gel solution” refers to a solution of silicon alkoxide or a derivative thereof used in the sol-gel method. In the present invention, examples of the solvent for the sol-gel solution include alcohols such as methanol and ethanol. In the initial sol solution of the sol-gel solution, the concentration of silicon alkoxide or a derivative thereof is preferably 10 to 50% by volume.

  In the present invention, any silicon alkoxide can be used, preferably tetramethoxysilane or tetraethoxysilane. Moreover, as a derivative | guide_body of a silicon alkoxide, a tetramethoxysilane oligomer etc. can be mentioned, for example.

  As a method of obtaining a structure that does not completely fill the inside of the polymer foam in the solution process, a method using a structure such as a surfactant micelle as a void, a wax or an oligomer that can be removed in a supercritical drying process is dispersed in a sol-gel solution. For example, a method of differentially producing organic particles having sublimability and removing them in vacuum can be considered. In the present invention, the foamed polymer structure is immersed in a sol-gel solution of silicon alkoxide or a derivative thereof, and in the sol-gel reaction by hydrolysis of the silicon alkoxide or the derivative thereof, before the silicon alkoxide or the derivative thereof is gelled, It is preferable that the structure is taken out from the sol-gel solution to form voids inside the foamed cells of the foamed polymer structure. More simply, after impregnating the polymer foam with the wet gel solution, compress the polymer foam to remove excess gel precursor, impregnate the compressed polymer foam with a certain amount of precursor and release the pressure There is a way to do it. In order to obtain a homogeneous surface coating structure, it is desirable to perform these operations immediately before the viscosity rapidly increases due to the progress of gelation. For that purpose, it is necessary to know in advance the gelation time of the precursor. The resulting gel structure has a low density and is easily damaged by moisture adsorption and contact with the liquid after drying. For the purpose of imparting hydrophobicity and liquid repellency, the hydrophobicity of silanol groups by silane coupling agents, etc. It is common to perform the conversion.

As a method of drying the coated wet gel of the above (2) to form a low density silica gel and obtaining the foamed polymer-silica composite of the present invention, a method of drying while avoiding the influence of the interfacial tension at the gas-liquid interface. Various known methods may be appropriately used, and are not particularly limited. Chemical drying control agent addition (DCCA) method, surfactant addition method, freeze-drying method, supercritical drying method, etc. are used, among which the aforementioned 0.1-0.2 g / cm ³ density silica is easy. The supercritical drying method obtained in (1) is preferred. Among them, a method using supercritical carbon dioxide, which can be operated at a low temperature and can be applied to various polymer foams, is preferable.

  The foamed polymer-silica composite thus obtained is a low-density monolith, but has a certain degree of flexibility and bending strength unlike a single silica airgel. Further, since the low density silica is dispersed in the bubbles of the polymer foam, there are advantages such as easy handling, less occurrence of cracks, and easy processing such as cutting.

  Since the foamed polymer-silica composite of the present invention is prepared so as to have voids therein, the silica gel composite polymer foam in a completely filled state (International Publication WO2007 / 146945 A2 (Patent Document 3)) Compared to the above, it is easily deformed and has excellent flexibility and moldability. Due to the presence of voids, convective heat transfer is large, and although the heat insulation performance is slightly inferior when compared as it is, it has sufficiently high performance as compared with existing heat insulating materials. On the other hand, during compression, deformation, etc., deformation occurs in such a way that low-density silica compresses voids, so convective heat transfer is relatively reduced, offsetting the increase in conduction heat transfer due to increased density. . Therefore, the heat insulating material using the foamed polymer-silica composite of the present invention is easily wound around, for example, a pipe having a complicated shape, and is suitable as a heat insulating and heat insulating material with little deterioration in heat insulating performance due to winding. It is.

  The heat insulating material having flexibility and moldability of the present invention uses the above foamed polymer-silica composite, and has a thermal conductivity of 101 kPa (in air) and 20 ° C. (near room temperature) of 0.03 W / mK or less. Preferably, it is 0.012-0.025 W / mK. Here, the thermal conductivity is a thermal conductivity measured by a hot wire method using foamed polyethylene as a standard.

  In addition, when the heat insulating material having flexibility and moldability of the present invention is compressed by 40% in the direction in which the compressive stress is applied, the integrity is not impaired and 101 kPa (in the atmosphere), 20 ° C. ( It is preferable that a thermal conductivity of 0.03 W / mK or less is maintained at around room temperature). “To compress 40% in the direction in which compressive stress is applied” means that the thickness of the material in the direction in which compressive stress is applied is {1− (thickness after compression / initial thickness)} × 100 = 40. Compressing to a thickness that satisfies the formula Here, “integrality” specifically refers to the integrity of the foamed polymer structure and the porous silica gel.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these.

[Example 1]
Formed into a disk shape with a diameter of 80 mm and a height of 10 mm into a sol solution in which tetramethoxysilane (manufactured by Tokyo Chemical Industry), methanol (commercial special grade), and 0.135 mol / L aqueous ammonia solution were mixed at a volume ratio of 2: 4: 1. Commercially available polyurethane foam (HR-50 manufactured by Bridgestone Corporation, porosity 98%, average foaming density 50/25 mm, average foaming diameter 680 μm) was immersed. Since the sol solution having the above composition gels in about 5 minutes at 20 ° C., the excess sol solution is compressed and removed by compressing the urethane foam 3 minutes after mixing the sol solution, and the inner wall of the urethane foam is immediately gelled. To form a structure in which silica wet gel was supported. Immediately after gelation, the mixture was impregnated with methanol, and kept at 60 ° C. for 2 days to age the gel. Thereafter, methanol was changed several times and maintained for 24 hours to remove unreacted tetramethoxysilane and water generated by gelation. The gel was further maintained in a 20% by mass 1,1,1,3,3,3-hexamethyldisilazane-methanol solution at 65 ° C. for 3 hours to hydrophobize the surface silanol groups with trimethylsilyl groups. Went. The hydrophobized gel is introduced into a pressure vessel together with methanol to prevent drying, and supercritical drying is performed at 80 ° C. and 20 MPa, which is a homogeneous phase condition of a methanol / carbon dioxide mixed system. A foamed polymer-silica composite was obtained. The density of this composite body determined from the volume and weight was 0.143 g / cm ³ . According to scanning electron microscope observation, this composite is mostly composed of low density silica supported so as to cover the surface of the polymer foam structure thickly, and the interior of the polymer foam is not completely filled. I understood. The density of the complex urethane obtained from the formula 1 was 93% when the density of the dense urethane was 1.2 g / cm ³ and the density of the dense silica was 2.3 g / cm ³ .

[Example 2]
In Example 1, a foamed polymer-silica composite was prepared in the same manner except that a commercially available melamine foam (Strider, 93% porosity) was used. The density of this composite was 0.131 g / cm ³ . According to scanning electron microscope observation, this composite is mostly composed of low density silica supported so as to cover the surface of the polymer foam structure thickly, and the interior of the polymer foam is not completely filled. I understood. The density of the complex melamine obtained by the formula 1 was 92% when the density of the dense melamine was 1.5 g / cm ³ and the density of the dense silica was 2.3 g / cm ³ .

[Comparative Example 1]
A foamed polymer-silica composite was obtained in the same manner as in Example 1 except that the sol solution was not compressed and removed, and the urethane foam was completely filled with silica wet gel. The density of this composite was 0.166 g / cm ³ . Observation with a scanning electron microscope revealed that in this composite, the low-density silica was almost entirely present so as to completely fill the voids of the polymer foam structure. The composite porosity was 92%.

[Comparative Example 2]
In Example 2, the same operation was performed except that the melamine foam was completely filled with the silica wet gel without compressing and removing the sol solution to obtain a foamed polymer-silica composite. The density of this composite was 0.158 g / cm ³ . Observation with a scanning electron microscope revealed that in this composite, the low-density silica was almost entirely present so as to completely fill the voids of the polymer foam structure. The composite porosity was 91%.

[Comparative Example 3]
In Example 1, without using polymer foam, a gel body only of silica airgel was prepared, and the subsequent operations were performed in the same manner to obtain silica airgel. The density of this silica airgel was 0.166 g / cm ³ . The porosity of the silica airgel was 93%.

Test example 1
The prepared gel was subjected to thermal conductivity measurement by a hot wire method using a foamed polyethylene as a standard under the conditions of 101 kPa (in the air) and 20 ° C. with a Kyoto Electronics QTM-500 type thermal conductivity measuring device. The results are summarized in Table 1.

  Further, the prepared sample was formed into a 20 × 10 × 80 mm rod shape, and using a three-point bending tester (Strograph R3 manufactured by Toyo Seiki Seisakusho) at a fulcrum distance of 70 mm and a displacement speed of 1 mm / min, JIS A three-point bending test was performed according to -K7171. Table 1 summarizes the bending stress at the time of 50% displacement of the thickness of the sample (when the silica airgel of Comparative Example 3 is broken).

  Moreover, the prepared sample was shape | molded in the plate shape of about 20x20x10 mm, and the compressive-stress response test was done according to JISK7181 using the load cell tester (Shimadzu Corporation autograph AG-5000A). Table 1 summarizes the compressive stress at 25% displacement of the sample thickness.

  From Table 1, in Examples 1 and 2, a composite having a lower density than Comparative Examples 1 and 2 was formed, and the results of observation by a scanning electron microscope are supported. Moreover, from the results of the three-point bending test and the compression test, it can be seen that Examples 1 and 2 have higher flexibility and formability. As in Comparative Example 3, the handleability was good without breaking with a small stress.

  Further, from Table 1, although the performance of Example 1 is slightly lower than that of Comparative Example 1, it maintains good heat insulation performance, and Example 2 has a low heat transfer coefficient equivalent to that of Comparative Example 2. It can be seen that it has excellent performance as a heat insulating material.

[Example 3]
For Example 2, a melamine foam composite airgel was prepared in the same manner except that the concentration of the aqueous ammonia solution was ½, that is, 0.0625 mol / L. The density of this composite gel was 0.09 g / cm ³ . The composite porosity was 94%.

  The melamine foam composite aerogel prepared above was measured for thermal conductivity in the same manner as in Test Example 1, and thereafter, using a load cell tester (Autograph AG-5000A, manufactured by Shimadzu Corporation), with reference to the thickness in the vertical direction. The sample was compressed 20% and deformed. There was little change in the horizontal direction. The thermal conductivity of the compressed gel was measured again in the same manner. Thereafter, the sample was again compressed to 40% with a load cell tester, and the same thermal conductivity measurement was repeated. The results are shown in Table 2.

  From Table 2, it can be seen that in Example 3, high thermal insulation performance of approximately the same level is maintained even when the density is changed by compression. This is because the increase in conduction heat transfer due to the increase in density of the composite due to compression was offset by the decrease in convection heat transfer due to the decrease in voids, and there was little change in thermal conductivity even during deformation. It is done. From this, it can be said that the foamed polymer-silica composite in the present invention functions as a heat insulating material that can maintain high heat insulating performance even after molding and deformation by compression.

  The foamed polymer-silica composite of the present invention can be used as a useful heat insulating material that can be used as a heat insulating material for houses and buildings, a heat insulating material for piping and various devices, and the like.

Claims (9)

A foamed polymer structure, and a porous silica gel with a density of 0.23 g / cm ³ or less coated on the inner wall of the foamed cell of the foamed polymer structure so as to have voids therein, have flexibility and moldability. A foamed polymer-silica composite. The foamed polymer-silica composite according to claim 1, wherein the porous silica gel is an airgel having a density of 0.1 to 0.2 g / cm ³ .   The foamed polymer-silica composite according to claim 1 or 2, wherein the foamed polymer structure has a porosity of 90% or more and 99.9% or less.   The foamed polymer-silica composite according to any one of claims 1 to 3, wherein the foamed polymer structure comprises a polyurethane foam or a composite thereof.   The foamed polymer-silica composite according to any one of claims 1 to 3, wherein the foamed polymer structure contains melamine foam or a composite thereof.   The foamed polymer-silica according to any one of claims 1 to 5, further comprising a step of performing a sol-gel reaction by hydrolysis of silicon alkoxide or a derivative thereof on the inner surface of the foamed cell of the foamed polymer structure. A method for producing a composite.   A foamed polymer structure is immersed in a sol-gel solution of silicon alkoxide or a derivative thereof to perform a sol-gel reaction by hydrolysis of silicon alkoxide or a derivative thereof, and before the silicon alkoxide or a derivative thereof is gelled, the foamed polymer structure The foaming according to any one of claims 1 to 5, further comprising a step of taking out the structure from the sol-gel solution and forming a silica gel void inside the foamed cell of the foamed polymer structure. A method for producing a polymer-silica composite.   A heat insulation having flexibility and moldability, comprising the foamed polymer-silica composite according to any one of claims 1 to 5, wherein the thermal conductivity at 101 kPa and 20 ° C is 0.03 W / mK or less. material.   When compressive stress is applied to the material and the material is compressed by 40% in the direction in which the compressive stress is applied, the integrity is not impaired and a thermal conductivity of 0.03 W / mK or less is maintained at 101 kPa and 20 ° C. The heat insulating material having flexibility and formability according to claim 8.