JP2008215538A - Vacuum insulation - Google Patents

Abstract

An object of the present invention is to provide a vacuum heat insulating material having excellent heat insulating performance even when the powder is made into a strong molded body in order to suppress powder scattering.
A vacuum heat insulating material (1) is a vacuum heat insulating material (1) in which a core material (2) is covered with an outer cover material (3) and the inside of the outer cover material (3) is sealed under reduced pressure. By mixing the mixed powder containing the fibers 5 with a temperature lower than the softening point and higher than the boiling point of water, the inorganic fibers 5 are plastically deformed in a pressurized state and the silica powder 4 is bonded. The density is 100 kg / m ³ or more and 240 kg / m ³ or less, and the core material 2 ensures the shape of the molded body, and a strong molded body can be obtained without increasing the density.
[Selection] Figure 1

Description

  The present invention relates to a vacuum heat insulating material.

  As the core material of the vacuum heat insulating material, a porous body such as a fiber system, a powder system, or a foamed resin system is used. Among these, since the powder system has fine voids and is excellent in internal pressure dependency, it is often applied to a case where heat insulation performance is required for a long period of time or a relatively high temperature.

  However, since the powder must be enclosed in the inner bag and used, the cost is increased by the amount required for the inner bag. Moreover, there is a problem that powder is scattered at the time of disposal, and the working environment is deteriorated. Therefore, there is a means of forming a powder to improve them.

  2. Description of the Related Art Conventionally, as a technique for forming a powder into a molded body, there is a vacuum heat insulating material using a molded body obtained by mixing and compressing ultrafine silica obtained by a wet method and a fiber material (see, for example, Patent Document 1).

Conventional vacuum heat insulating materials are lightweight and have excellent heat insulating performance by using, as a support material, an ultrafine particle silica molded body having low thermal conductivity and excellent compression resistance.
Japanese Unexamined Patent Publication No. 61-250481

However, although the density of the conventional molded body is described as 220 to 460 kg / m ³ , it has a strength that cannot be held by hand at a low density, and it collapses into pieces. The cause of the collapse is probably due to the small contact area between the powders and the powder and the fibers, and the fact that the spring back of the fibers cannot be suppressed. Further, handling is possible when the density is increased to 250 kg / m ³ or more, but there is a problem that heat insulation performance deteriorates when the density is increased.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a vacuum heat insulating material excellent in heat insulating performance even when the powder is made into a strong molded body in order to suppress scattering of the powder. And

In order to achieve the above-mentioned object, the vacuum heat insulating material of the present invention is a core material in which a mixed powder containing at least silica powder and inorganic fibers is heated at a temperature below the softening point and above the boiling point of water. In the molding, the inorganic fibers are plastically deformed in a pressurized state and the silica powder is bonded, whereby the density is set to 100 kg / m ³ or more and 240 kg / m ³ or less.

  When a powder having a small particle diameter is used as the core material, the thermal contact resistance is increased, so that good initial heat insulation performance is obtained, and because fine voids are formed, good heat insulation performance is obtained. Silica powder is a desirable material for use as a core material because of its low cost among powders having an average primary particle size of nano-order.

  In the case of molding powder, silica has a large number of hydroxyl groups on the surface, so that the strength of the molded body is easily improved. Moreover, when a fiber is an inorganic fiber, not only outgas is suppressed, but since the affinity with the silica powder is high, the strength of the molded body is further improved.

  At this time, in order to ensure the strength of the molded body, it is a general method to increase the density, but by using the molding method as a means called a heating press, the inorganic fibers are plastically deformed, and the silica powder By joining the bodies, the shape can be secured by suppressing the spring back of the fiber, so that a strong molded body can be obtained without increasing the density.

  In the vacuum heat insulating material of the present invention, since the core material is a powder system excellent in internal pressure dependency, heat insulating performance can be ensured over a long period of time. In addition, a molded body composed of silica powder and inorganic fibers has a high affinity with each other, and further, by thermoforming, the inorganic fibers that have been plastically deformed are held by the bonded silica powder at room temperature. Since the strength of the molded body is improved as compared with the case of molding, handling properties are improved, and scattering of powder at the time of disposal can be suppressed.

  In addition, since powder fall off from the molded body can be suppressed, adhesion of powder to the box body and jacket material and the shaving of the core material are suppressed even when the core material is inserted into the box body and jacket material. Workability is improved. Moreover, since a molded object is obtained without densifying, favorable heat insulation performance is securable.

The invention of a vacuum heat insulating material according to claim 1 is a vacuum heat insulating material in which a core material is covered with a jacket material and the inside of the jacket material is sealed under reduced pressure, and the core material includes at least the silica powder and the By mixing the mixed powder containing inorganic fibers with heat molding at a temperature below the softening point and above the boiling point of water, the inorganic fibers are plastically deformed in a pressurized state, and the silica powder is combined, The density is 100 kg / m ³ or more and 240 kg / m ³ or less, and the powder strength can be suppressed because the strength of the compact is improved.

  Silica powder has an average primary particle size of nano-order, and therefore has high thermal contact resistance and excellent initial heat insulating performance, and also has excellent heat insulating performance over time because it forms fine voids.

  The combination of silica and inorganic fibers can provide a molded body having higher strength than when other materials are used. This is because silica is a powder having a small particle size, and intermolecular force works and particles tend to adhere to each other, particles have a hydroxyl group on the silica surface, and particles easily bond to each other, or silica and inorganic It is conceivable that they are easy to adhere to each other because of the high affinity of fibers.

  When the core material is a molded body, the inner bag is not necessary, so that the cost can be reduced. Compared to powders that do not solidify, the thickness unevenness is reduced, making it easier to reduce the thickness, and reducing the difference between the thickness in atmospheric pressure and the thickness after vacuum sealing, resulting in excellent dimensional stability. A vacuum heat insulating material can be obtained. Moreover, handling property improves and it can suppress the dusting at the time of disposal.

The density is preferably in the range of 100 kg / m ³ or more from the viewpoint of maintaining the shape as a molded body and 240 kg / m ³ or less from the viewpoint of obtaining good heat insulation performance.

  As long as the molded body is a method in which plastic deformation of fibers and silica bonding occur, the heating molding method is not particularly specified. However, if the softening point of the inorganic fiber or silica is exceeded, heat transfer due to the solid increases due to a marked increase in the number of fibers, or between the powders, or between the fibers and powder, and the heat insulation performance deteriorates. It is desirable that the temperature is lower than the respective softening point. In order to obtain better heat insulation performance, it is more desirable to carry out at a temperature below the strain point. In addition, if the temperature is too low, the adsorbed water on the silica surface inhibits the bonding between the silicas, so it is desirable that the temperature be higher than the boiling point of water.

  The silica powder in the present invention is not particularly specified, and is a dry silica produced by a dry method such as a flame method, an arc method or a plasma method, or a wet silica produced by a wet method such as a precipitation method or a gel method. It can be used. When the average primary particle size is small, the heat insulation performance is improved, and the temperature can be lowered and shortened in heat molding. Therefore, the primary particle size is preferably 50 nm or less, more preferably 10 nm or less.

  Moreover, the inorganic fiber in the present invention is not particularly specified. The thinner the fibers, the lower the solid thermal conductivity, so that the heat insulation performance is improved, and the surface energy of the fibers is increased, so that the bonding strength with the silica particles is improved, and the strength of the molded body is improved. The fiber diameter is desirably 10 μm or less because the temperature of the heating press can be reduced and the time can be shortened. In addition, the fiber length is not particularly specified, but in order to improve the strength of the molded body, it is more desirable that a fiber having a length of mm unit, desirably 5 mm or more exists.

  According to a second aspect of the present invention, the silica powder according to the first aspect of the invention includes wet silica, and the cost can be reduced, and the wet silica is replaced with dry silica. Compared to the bulk density of the material, the powder is less likely to scatter.

  In the case of dry silica, the adhesion between particles is stronger than that of wet silica. Therefore, it is possible to obtain a low-density and strong molded body even at room temperature molding. Since the cost is about 10 times higher, the material cost increases.

In addition, dry silica is very difficult to handle because it has a low bulk density, so that the powder is likely to scatter and the powder is likely to adhere to devices due to static electricity. Therefore, it is more desirable to use wet silica among the silica powders. However, in the case of wet silica, a molded body having a strength that can be handled can be obtained in normal temperature molding unless the density exceeds 250 kg / m ³ . In this case, the heat insulation performance deteriorates. However, in thermoforming, it becomes possible to obtain a strong molded body with low density even with wet silica, and good heat insulation performance can be secured.

  The silica powder in the present invention may be 100% wet silica or other silica powder such as dry silica may be mixed, but more wet silica can be manufactured at lower cost. Become.

  The invention of the vacuum heat insulating material according to claim 3 is such that the inorganic fiber in the invention according to claim 1 or 2 contains glass fiber, and adhesion strength with silica is improved, and the strength of the molded body is further improved. As a result of the improvement, powder scattering can be further suppressed.

  The combination of silica and glass fiber has an effect of suppressing powder scattering because the glass fiber has a hydroxyl group on the surface, so it has a high affinity with the hydroxyl group present on the silica powder surface and is easily attached to each other. As compared with the case where other materials are used, not only is it high, but also the adhesion between the powder and the fibers is improved, so that a strong molded body can be obtained as compared with the case where other materials are used.

  Further, it is more preferable that the glass fiber is an alkali-containing glass containing sodium and potassium components because molding at a lower temperature is possible.

  In addition, although the inorganic fiber in this invention may be 100% of glass fiber, other inorganic fibers may be mixed, but the more the glass fiber is contained, the more the molded body strength is improved.

  The invention of the vacuum heat insulating material according to claim 4 is a material in which the content of the inorganic fiber in the invention according to any one of claims 1 to 3 is 1 wt% or more and 60 wt% or less, and is strong. A molded body can be obtained, and good heat insulation performance can be secured.

  The fiber plays the role of a skeleton in the molded body, but it is difficult to secure strength because the skeleton structure cannot be formed without the fiber, and when the fiber exceeds 60 wt%, the fiber becomes dominant and the spring back cannot be suppressed. The strength cannot be ensured, and the dependency of the heat insulation performance on the internal pressure deteriorates due to the coarse pores. Therefore, it is desirable that the content of the inorganic fiber is 1 wt% or more and 60 wt% or less in terms of both strength and heat insulation performance.

  The invention of the vacuum heat insulating material according to claim 5 is such that the core material according to any one of claims 1 to 4 contains conductive powder, and the heat insulating performance is improved.

  When conductive powder is mixed with silica, the heat insulation performance is improved. The reason for this is thought to be a decrease in solid thermal conductivity due to a decrease in solid contact area due to the crushing of silica agglomeration by the conductive powder.

  The conductive powder in the present invention is not particularly specified as long as it is a conductive powder, and powdered carbon, metal powder, metal oxide powder, metal-doped powder, and the like can be used. You may use multiple types of these. Among these, powdery carbon is desirable from the viewpoint of cost and performance. Even when the content is 1 wt%, an improvement in the heat insulation performance is recognized. When the content is 30 wt%, the thermal conductivity is minimized, and when the content exceeds that, the thermal conductivity increases again.

  Further, when the content of powdery carbon increases, outgas from the powdery carbon affects the heat insulation performance over time, so 1 wt% or more and 30 wt% or less is desirable. In addition, the content rate of electroconductive powder here refers to the weight ratio of electroconductive powder when the mixed powder which consists of silica powder and inorganic fiber is set to 100. FIG.

  With the configuration of the present invention, a strong molded body can be obtained without using a binder that acts to bind powder and powder or fibers and powder. By not using the binder, heat transfer of the solid due to the binder does not occur, so that the heat insulation performance is improved as compared with the case where the binder is used.

  In order to further improve the strength, a binder may be used, but in order to ensure good heat insulation performance, the amount added is desirably 5 wt% or less. The binder may be an inorganic binder such as water glass, colloidal silica, or alumina sol, or an organic binder such as starch or phenol resin, but is not particularly specified.

  Moreover, the jacket material in this invention can use what uses the laminate film which has barrier property, and the structure is not specified in particular.

  The innermost heat-bonding layer of the laminate film includes low density polyethylene, linear low density polyethylene, high density polyethylene, unstretched polypropylene, polyacrylonitrile, unstretched polyethylene terephthalate, unstretched nylon, unstretched ethylene-polyvinyl alcohol. A polymer resin or the like can be used and is not particularly specified.

  Moreover, in order to suppress gas intrusion from the outside, a metal foil, a vapor deposition film, a coating film, a vapor deposition coating film, or the like can be used. The type and number of layers are not particularly specified.

  The metal foil is not particularly specified such as aluminum, stainless steel, iron or a mixture thereof. Moreover, the material of the plastic film used as the base material for vapor deposition or coating is not particularly specified, such as polyethylene terephthalate, ethylene-polyvinyl alcohol copolymer resin, polyethylene naphthalate, nylon, polypropylene, polyamide, and polyimide.

  Further, the material for vapor deposition is not particularly specified such as aluminum, cobalt, nickel, zinc, copper, silver, silica, alumina, diamond-like carbon, and a mixture thereof. Also, the coating material is not particularly specified such as PVA, polyacrylic acid resin or a mixture thereof. In addition, the stacking order of vapor deposition and coating in the vapor deposition coating film is not specified.

  Further, it is possible to further provide a film on the outer layer or the intermediate layer for the purpose of improving pinhole resistance and abrasion resistance, imparting flame retardancy, and further improving barrier properties.

  Here, the film provided on the outer layer or the intermediate layer is nylon, ethylene / tetrafluoroethylene copolymer resin, polyethylene terephthalate, polyethylene naphthalate, polypropylene, ethylene-polyvinyl alcohol copolymer resin, etc. , Not particularly specified. Moreover, a vapor deposition film, a coating film, a vapor deposition coating film may be sufficient, and also metal foil may be laminated | stacked.

  The bag shape of the jacket material is not particularly specified, such as a four-side sealed bag, a gusset bag, a three-side sealed bag, a pillow bag, or a center tape seal bag.

  Further, the jacket material may be a container having a barrier property, for example, a container formed of resin.

  The material and configuration are not particularly specified, and metals such as aluminum, stainless steel, iron, polyethylene, polypropylene, polyethylene terephthalate, ethylene-polyvinyl alcohol copolymer resin, polyethylene naphthalate, nylon, polypropylene, polyamide, polyimide, etc. These resins can be used. Moreover, you may use what vapor-deposited and coated these resins. In order to improve the barrier property, these materials may be used in multiple layers.

  In order to further improve the initial heat insulation performance and the temporal heat insulation performance of the vacuum heat insulating material, it is possible to use a moisture adsorbent or a gas adsorbent. The type of adsorbent is not particularly specified, and calcium oxide, magnesium oxide, barium oxide, zeolite, silica gel, hydrotalcite, etc. can be used. Even if these are used alone, they can be used in combination of two or more. May be.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a vacuum heat insulating material according to Embodiment 1 of the present invention. As shown in FIG. 1, the vacuum heat insulating material 1 according to the present embodiment is a vacuum heat insulating material 1 in which a core material 2 is covered with a jacket material 3 and the inside of the jacket material 3 is sealed under reduced pressure. In addition, the mixed powder containing at least the silica powder 4 and the inorganic fiber 5 is heat-molded at a temperature lower than the respective softening points and higher than the boiling point of water, so that the inorganic fiber 5 is plastically deformed in a pressurized state and the silica powder. By bonding the body 4, the density is 100 kg / m ³ or more and 240 kg / m ³ or less.

  Next, the manufacturing method of the vacuum heat insulating material 1 is demonstrated about the vacuum heat insulating material 1 of this Embodiment comprised as mentioned above.

  The core material 2 obtains a molded body by filling a molding die with a powder in which silica powder 4 and inorganic fibers 5 are mixed in a predetermined ratio, and pressing in a heated state.

  The outer cover material 3 is formed into a bag shape by heat-sealing three sides of two laminate films facing each other with the same size of a gas barrier property rectangle having a heat-welding layer on one side and facing each other. .

Next, the dried core material 2 is inserted from the opening of the jacket material 3 that is sealed on three sides. This is installed in the chamber, the inside is decompressed, and the opening is heat sealed to obtain the vacuum heat insulating material 1 having a core density of 100 kg / m ³ or more and 240 kg / m ³ or less.

  Since the combination of the silica powder 4 and the inorganic fiber 5 has a high affinity, a strong molded body was obtained.

  Moreover, since powder fall was suppressed by the molded object strength being high, the insertion to the jacket material 3 also became easy. Moreover, when this molded body was inserted into the box, it was easy because there was little powder falling off or scraping of the surface layer. Moreover, powder scattering at the time of disposal could be suppressed.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Example 1)
The core material 1 is a molded body composed of wet silica as the silica powder 4 and glass fibers as the inorganic fibers 5, and the mixing ratio is 100 wt%: 10 wt%. The heating press conditions were 200 ° C. for 1 hour. The core density of the vacuum heat insulating material 1 is 210 kg / m ³ .

  In this example, it was possible to suppress the spring back and obtain a strong molded body by thermoforming. Moreover, the initial heat insulation performance of the vacuum heat insulating material 1 was 0.0055 W / mK, which was excellent. When a temperature acceleration test assuming heat-insulating performance over time was performed, it was excellent at 10060 ° C. and 1 month later at 0.0060 W / mK.

(Example 2)
The core density was examined. The conditions other than the density are the same as in Example 1.

When the density was lowered, it was possible to handle the core material 2 alone up to 100 kg / m ^3, but if it was lower than this, it could not be lifted.

In addition, as the density was increased, the strength improved, but with this, the heat insulation performance gradually deteriorated and exceeded 0.0080 W / mK at 250 kg / m ³ , and the powdered silica contained in the inner bag The result was worse than when powder was used as the core.

Therefore, the density of the core material 2 is desirably 100 kg / m ³ or more from the viewpoint that the shape as a molded body can be secured, and 240 kg / m ³ or less from the viewpoint of obtaining good heat insulation performance.

(Example 3)
The kind of inorganic fiber 5 was examined. The conditions other than the inorganic fiber 5 are the same as in Example 1.

  As the inorganic fiber 5, glass fiber and silica alumina fiber were compared. When either fiber is used, the initial heat insulating performance is 0.0055 W / mK, and a strong molded body having no problem in handling is obtained. However, a stronger molded body is obtained when glass fiber is used. It was. Therefore, it is more desirable to use glass fiber as the inorganic fiber 5.

Example 4
The mixing ratio of the inorganic fibers 5 was examined. The conditions other than the mixing ratio of the inorganic fibers 5 are the same as in Example 1.

  When the mixing ratio of the inorganic fibers 5 was increased, the strength decreased due to the difficulty of springback of the fibers as the mixing ratio of the inorganic fibers 5 increased, but the mixing ratio was 100 wt%: up to 60 wt%. As a result, the shape as a molded body could be secured.

  However, when the mixing ratio of the inorganic fibers 5 exceeds 60 wt%, it becomes difficult to suppress the spring back, and handling becomes difficult. Moreover, when the mixing ratio of the inorganic fibers 5 was lowered, a strong molded body could be obtained with a mixing ratio of 100 wt%: 1 wt%, but when the ratio was lower than that, the skeleton structure could not be formed and the strength deteriorated. did. Therefore, the content of the inorganic fiber 5 is desirably 1 wt% or more and 60 wt% or less.

(Example 5)
The temperature conditions of the hot press for forming the core material 2 were examined. The conditions other than the temperature condition are the same as in the first embodiment.

  When the temperature of the hot press was lowered, the spring back could be suppressed at a temperature of 100 ° C. or higher, which is the boiling point of water, and a molded product could not be obtained. Further, when the temperature of the heating press was increased, when the softening point of the inorganic fibers 5 or the silica powder 4 was exceeded, the bonding points between the inorganic fibers 5 or between the silica powders 4 or between the inorganic fibers 5 and the silica powder 4 Significantly increased, the thermal conductivity exceeded 0.0100 W / mK.

  Therefore, it is desirable that the temperature of the heating press be equal to or higher than the boiling point of water and lower than the thermal deformation temperature of silica powder or inorganic fibers.

(Example 6)
The influence of containing conductive powder in the core material 2 was evaluated. Carbon black, which is powdery carbon, was used as the conductive powder. The content of the conductive powder is such that the weight ratio between the silica powder 4 and the inorganic fibers 5 is fixed at 10: 1 and the mixed powder of the silica powder 4 and the inorganic fibers 5 is 100. Evaluation was made by changing the weight ratio of the body. The material of the silica powder 4 and the inorganic fibers 5 and the heating press conditions are the same as in Example 1.

  When the conductive powder is not included, the initial heat insulation performance is 0.0055 W / mK, whereas even when the conductive powder is 1 wt%, the heat insulation performance is improved to 0.0054 W / mK, and the minimum value is 0.3 at 30 wt%. It became 0050 W / mK, and when it exceeded that, it began to deteriorate again.

  Also, if the weight ratio of the conductive powder exceeds 30 wt%, the amount of outgas from the conductive powder will increase and affect the thermal insulation performance over time, so if conductive powder is added to improve the thermal insulation performance The content is preferably 1 wt% or more and 30 wt% or less.

(Comparative Example 1)
The core material was pressed at room temperature. The conditions other than the press temperature are the same as in Example 1.

  The compact collapsed and shattered over time after the press was removed by the glass fiber springback. Even if the press time was extended to one day, the disintegration progressed as time passed since the press was removed.

  In addition, even if it is normal temperature press, if a density is increased, a molded object can be obtained. However, when the density is increased to a strength at which handling is possible, the heat insulation performance becomes 0.0080 W / mK, which deteriorates.

  Therefore, it is difficult to obtain a strong compact with a low density by a normal temperature press.

(Comparative Example 2)
The press condition of the core material was changed. The condition was that the mixed powder was heated at 200 ° C. for 1 hour without pressing, and then pressed at room temperature for 1 hour. In addition, it is the same as that of Example 1 except press conditions.

  As in Comparative Example 1, the compact collapsed over time after removing the press due to the springback of the glass fiber.

  Therefore, in order to obtain a strong molded body, it is necessary to press simultaneously with heating.

(Comparative Example 3)
Only glass fiber as the inorganic fiber 5 or only wet silica as the silica powder 4 was heated and pressed. The condition is 200 ° C. for 1 hour as in Example 1.

  In the case of the inorganic fiber 5 alone, the fiber remained cottony and did not become a molded body. In the case of the silica powder 4 alone, the strength of the compact was weak because there was no cross-linking structure, and when it was lifted, it was broken into small pieces.

  Therefore, the material of the core material 2 needs to be a mixed powder of at least silica powder 4 and inorganic fibers 5.

  As described above, according to the example and the comparative example in the first embodiment, in order to form the silica powder 4 with a low density and high strength, it is a mixed powder composed of the silica powder 4 and the inorganic fibers 5. When this mixed powder is used as a molded body, it is desirable to perform heating and pressurization at the same time, and the addition amount of the inorganic fiber (glass fiber) 5 at this time is 1 wt% or more and 60 wt% The following were found desirable: Further, it has been found that it is desirable to contain conductive powder in order to further improve the heat insulation performance.

(Embodiment 2)
FIG. 2 is a vertical cross-sectional view of a refrigerator that is an example of a heat insulating box to which the vacuum heat insulating material according to Embodiment 2 of the present invention is applied.

  In FIG. 2, the refrigerator 6 foams the vacuum heat insulating material 1 according to the first embodiment inside a box composed of an inner box 7 and an outer box 8, and foams a space other than the vacuum heat insulating material 1 with a hard urethane foam 9. Filled. A vacuum heat insulating material 1 is also disposed between the machine room 10 and the interior 11.

  When the electric power consumption of the refrigerator comprised in this way was measured, it was falling 15% from the refrigerator which does not mount | wear with the vacuum heat insulating material 1, and the outstanding heat insulation effect was confirmed.

  Since the vacuum heat insulating material 1 of the present invention was excellent in heat insulating performance over time, an accelerated test assuming 10 years later was performed, and only 2-3% of the initial power consumption was changed.

  In the vacuum heat insulating material according to the present invention, since the core material is a powder system excellent in internal pressure dependency, the heat insulating performance can be maintained over a long period of time. For this reason, it can be used as a building material that requires heat insulation performance for a very long time. Moreover, if it is used for a cold insulation device such as a refrigerator, or a thermal insulation device such as an electric water heater, a rice cooker, a thermal insulation cooker, or a hot water heater, it shows an excellent energy saving effect over a long period of time.

  In addition, since the core material is a molded body, even when it is thinned, thickness unevenness is reduced, so notebook computers, copiers, printers, projectors, etc. that require high thermal insulation performance in a small space are required. Application to office equipment is also possible. Also, it can be applied to uses such as container boxes and cooler boxes that require cold storage, cold protection equipment, bedding, and the like.

  Moreover, the core material of this invention is not restricted to the application to the vacuum heat insulating material which has the jacket material which consists of a laminate film. For example, a vacuum heat insulation box body comprising at least an outer box and an inner box made of a gas barrier material, having a vacuum heat insulation structure by providing a core material in a space between the outer box and the inner box, and depressurizing the space. Application to is also possible.

Sectional drawing of the vacuum heat insulating material in Embodiment 1 of this invention The longitudinal cross-sectional view of the refrigerator which applied the vacuum heat insulating material in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum heat insulating material 2 Core material 3 Cover material 4 Silica powder 5 Inorganic fiber

Claims (5)

A vacuum heat insulating material in which a core material is covered with an outer cover material and the inside of the outer cover material is sealed under reduced pressure, wherein the core material is a mixed powder containing at least silica powder and inorganic fibers, and less than each softening point The density was set to 100 kg / m ³ or more and 240 kg / m ³ or less by thermoforming at a temperature higher than the boiling point of water and plastically deforming the inorganic fibers in a pressurized state and bonding the silica powder. Vacuum insulation material characterized by   The vacuum heat insulating material according to claim 1, wherein the silica powder includes wet silica.   The vacuum heat insulating material according to claim 1 or 2, wherein the inorganic fiber includes glass fiber.   The content rate of the said inorganic fiber is 1 wt% or more and 60 wt% or less, The vacuum heat insulating material as described in any one of Claim 1 to 3 characterized by the above-mentioned.   The vacuum heat insulating material according to any one of claims 1 to 4, wherein the core material includes conductive powder.