JPH06105151B2 - Vacuum insulation board manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for manufacturing a vacuum heat insulating plate, which is used in, for example, a refrigerator, and which includes a container whose inside is depressurized.

(Prior Art) In a conventional heat insulating plate formed by filling a container such as a plastic film with a heat insulating material such as powder or fibrous material and depressurizing the inside, the thermal conductivity greatly changes depending on the degree of vacuum inside.

Generally, as the pressure inside the container increases, the thermal conductivity increases and the heat insulating performance decreases, and it is essential to increase the vacuum degree to improve the heat insulating performance. In order to increase the degree of vacuum, conventionally, an adsorbent such as zeolite or activated carbon was placed in a container together with this heat insulating material to adsorb and remove moisture, oxygen, etc. of the residual gas. But this method is chemically inert,
Nitrogen, which occupies most of the residual gas, could not be removed completely, and there was a limit to raising the degree of vacuum.

(Problems to be Solved by the Invention) The present invention has been made in view of the fact that there is a limit to increasing the degree of vacuum in the above-mentioned conventional technology, and the degree of vacuum is higher.
An object of the present invention is to provide a method for manufacturing a vacuum heat insulating plate having excellent heat insulating performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a heat insulating material filled in a closed container and a gas adsorbent contained in the heat insulating material. In the method for manufacturing a vacuum heat insulating plate, the air inside the container is replaced with a gas having a high adsorbability with respect to the gas adsorbent, and then the inside of the container is depressurized.

(Operation) According to the present invention, by the above means, the gas adsorbent is put into a container together with the heat insulating material, the air in the container is replaced with a gas having a high affinity with the adsorbent, and then the inside of the container is degassed to remove residual gas. The amount of nitrogen inside is reduced as much as possible, and the degree of vacuum of the vacuum insulation material is raised to improve the insulation performance.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIG.

FIG. 1 is a sectional view showing the structure of a vacuum heat insulating plate used in Examples and Comparative Examples of the present invention. That is, an inner bag 3 made of kraft paper containing a heat insulating material 2 made of pearlite powder having an average particle diameter of 10 μm is placed in a sealed film container 1 made of polyester laminated with aluminum foil. In Example and Comparative Example 2, a kraft paper pouch containing an oxygen adsorbent made of fine iron powder was further included, but in Comparative Example 1, this was not included. In Comparative Examples 1 and 2, air was degassed as it was to manufacture a vacuum heat insulating plate. In the examples, after the oxygen adsorbent was added, first the air in the container was degassed to 1 torr, then oxygen was added to 10 torr, and after degassing, a vacuum heat insulating plate was prepared. The pressure immediately after evacuation was set to 5 × 10 ^-1 torr in both Comparative Example and Example.

In the examples, 90% or more of the residual water content is occupied by oxygen,
Due to the effect of the oxygen scavenger, oxygen was adsorbed after being sealed and the degree of vacuum further increased, improving the heat insulation performance. However, in Comparative Example 2, about 80% of the residual gas was occupied by the inert nitrogen, the effect of the oxygen scavenger was only about 1/5 of that of the Example, and the degree of vacuum and the heat insulating performance were not improved so much. Further, in Comparative Example 1, the residual gas was not adsorbed, and the degree of vacuum and the heat insulating performance were not improved. The results are summarized in Table 1.

The present invention is not limited to the above embodiment,
A combination of gas adsorbents which have a particularly high absorption / adsorption performance for a specific gas and do not release the gas even after the adsorption is sufficient. For example, with respect to oxygen, anhydrous ferrous sulfate or anhydrous chloride first
Similar effects can be obtained by combining with reducing agents such as tin and pyrocarol, soda ash for carbon dioxide, and fine palladium powder for hydrogen.

[Advantages of the Invention] As described above, according to the present invention, a gas adsorbent is placed in a vacuum heat insulating plate, and when degassing, the gas adsorbent reacts particularly with the gas adsorbent to replace the gas absorbed in the heat insulating plate. Thus, the degree of vacuum can be further increased after the container is sealed at the time of manufacturing the vacuum heat insulating plate. This can improve the heat insulating performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a vacuum heat insulating plate used in Examples and Comparative Examples of the present invention. 1 ... Sealed film container, 2 ... Insulation material, 3 ... Inner bag.

Claims (1)

[Claims] 1. A method for manufacturing a vacuum heat insulating plate comprising a heat insulating material filled in a closed container and a gas adsorbent contained in the heat insulating material, wherein the air in the container is covered with the gas adsorbent. A method for producing a vacuum heat insulating plate, comprising depressurizing the inside of a container after replacing the gas with a gas having a high adsorption capacity.