JPS61103090A - Vacuum heat-insulating structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a vacuum insulation structure that can be used for insulation walls of household refrigerators and the like.

[Prior art]

Rigid polyurethane foam has been widely used as a heat insulating material for household refrigerators. Its insulation performance has been improved year by year, with a thermal conductivity of approximately 0.015kcal/mh''C.
This has been reduced to almost the theoretical limit value. However, from the viewpoint of energy saving and space saving, there is a demand for a heat insulating material with even better heat insulating performance.

By the way, the vacuum insulation method is known as a highly efficient insulation method and is used for liquefied gas tanks, etc., but this method involves filling a metal container with a heat insulating spacer material, evacuating it to a high vacuum, and sealing it. There are nine things you can do. This is done by evacuation to a high vacuum, which lengthens the mean free path of the gas molecules in the heat insulating spacer material and prevents collisions between gas molecules! 7 Something that impedes the conduction of heat, 0.01 kcal
/mh''C or less. However, when using this vacuum insulation material for household refrigerators, etc., the insulation area is very small compared to liquefied gas tanks, etc., so the influence of surface heat conduction of the container is small. This causes the vacuum insulation method to become less effective.

Therefore, it is conceivable to form the vacuum container with a material other than metal that has low thermal conductivity, such as plastic.
Plastics have the drawback that gas permeation is large, and the degree of vacuum inside the container deteriorates due to air permeating from outside the container, which deteriorates its insulation performance. Another drawback is that plastic is weak in strength, and once a vacuum container is punctured by even a small scratch, the vacuum inside the container will be destroyed and the container will no longer function as a heat insulator.

One possible way to suppress this air permeation and increase the strength of the vacuum container is to embed the vacuum container in an organic foam insulation material. There are carbon dioxide gas produced by the reaction between the foaming aid water and Ruru inocyanate, the raw material for the organic foam insulation material, as well as water vapor from unreacted water. The problem remains that it diffuses and gradually permeates into the vacuum container, degrading the degree of vacuum.

Normally, when vacuum insulation materials are used in liquefied gas tanks, etc., activated carbon is used as a so-called getter material that adsorbs gas molecules remaining in the vacuum container and maintains the degree of vacuum in the vacuum container. Activated carbon can adsorb large amounts of all kinds of gases only after it is cooled to an extremely low temperature using liquefied gas, etc., and when used in household refrigerators, etc., as in the present invention, it must be used at room temperature.
Activated carbon's original adsorption properties are that it can adsorb a considerable amount of organic gases such as chlorofluorocarbons, but it is hardly able to adsorb polar inorganic gases such as carbon dioxide and water vapor.

〔the purpose〕

The present invention fills a plastic container with a silica-alumina adsorbent as a getter material together with a heat insulating spacer material, thereby preventing fluorocarbon gas, carbon dioxide gas, and The purpose is to trap water vapor, etc., prevent deterioration of the vacuum inside the plastic container, and maintain the insulation performance of the vacuum insulation material over a long period of time.

〔Example〕

The drawings are sectional views showing the entire configuration of the vacuum heat insulating structure according to the present invention. In the figure, l is a plastic container and 2
is a heat insulating spacer material filled in the plastic container l. 3 is an organic foam heat insulating material in which the plastic container I is buried. 4 is the plastic container l
This is a silica-alumina-based adsorbent of Gestar material that is filled together with the heat insulating spacer material 2 inside. The inside of the plastic container 1 is evacuated to a high vacuum.

This plastic container l is for keeping the inside of the vacuum insulation material in a vacuum, and various thermosetting resins and thermoplastic resins can be used for the material, but it is easy to vacuum seal, and In order to suppress gas permeation through the vacuum container, a plastic laminate film having a metal foil or a metal vapor-deposited film is preferable.

The heat insulating spacer material 2 is used to maintain the shape of the plastic container 1 against atmospheric pressure, and to divide the inside of the heat insulating space into smaller spaces to obtain a vacuum heat insulating effect even at a relatively low degree of vacuum. In terms of materials, inorganic powders such as perlite, calcium silicate, diatomite, and silica, fibers such as glass wool, ceramic wool, and rock wool, and organic foams such as foamed polyurethane and foamed area resin can be used. be.

Furthermore, the organic foam insulation material 3I'i, the plastic container l
There is a movement to reduce the amount of air (such as nitrogen, oxygen, and water vapor) that passes through the vacuum insulation, and to increase the strength of vacuum insulation. As this organic foam heat insulating material 3, commonly used rigid foam polyurethane or the like can be used. In the foaming material used for foaming this organic foam insulation material 3, chlorofluorocarbon gas may be used alone, but in most cases water is added as a foaming aid to lower the foaming pressure and increase the strength of the generated 7 ohm. It is also used by adding it at the same time.

This foaming aid water reacts with incyanate, which is a raw material for the organic foam insulation material, to generate carbon dioxide gas, and a foam is formed by this carbon dioxide gas and vaporized fluorocarbon gas.

The silica alumina adsorbent 4 is the organic foam heat insulating material 3
This is a getter material for adsorbing fluorocarbon gas, carbon dioxide gas, water vapor, etc. that diffuse through the plastic container 1 and gradually enter and permeate, thereby keeping the plastic container 1 at a high vacuum. It is possible.

Unlike activated carbon, silica-alumina-based adsorbents can adsorb polar inorganic gases such as carbon dioxide and water vapor in addition to fluorogas, so they can absorb carbon dioxide and This can prevent the degree of vacuum from deteriorating due to water vapor.

The method for encapsulating the silica-alumina-based adsorbent 4 as a getter material may be by mixing it with the heat-insulating spacer material 2 as in this example, or by separately packaging and encapsulating only the silica-alumina-based adsorbent 4. Needless to say, it's a good thing.

〔effect〕

As described above, according to the present invention, since the fluorocarbon gas, carbon dioxide gas, and water vapor that permeate into the plastic container can be removed by the silicalumina-based adsorbent as the getter material, it is possible to maintain the horse harness empty for a long period of time. This makes it possible to obtain a vacuum insulation structure that has stable quality and high insulation performance over a long period of time.

[Brief explanation of the drawing]

The drawing is a sectional view showing the configuration of a vacuum insulation structure according to the present invention. 1...Plastic container, 2...Insulating spacer material, 3...Organic foam insulation material, 4...Silica alumina-based adsorbent 0

Claims (1)

[Claims] 1. Fill a plastic container with a silica-alumina adsorbent as a getter material along with a heat insulating spacer material,
A vacuum insulation structure characterized in that a vacuum insulation material that vacuum-seals the inside of the plastic container is embedded in an organic foam insulation material.