JPH0820175B2 - Insulated box - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating box used in a refrigerator / freezer or the like.

2. Description of the Related Art In recent years, from the viewpoint of energy saving, it has been strongly desired to reduce the thermal conductivity of the foamed heat insulating material and improve the heat insulating property. Therefore, in the production of rigid urethane foam, which is a typical foam insulation material, various improvements have been made from the raw material side by removing the polyether polyol and isocyanate used as the main raw materials, the foam stabilizer, the catalyst, and the foaming agent used as the auxiliary raw materials. Efforts are being made. In order to reduce the thermal conductivity of rigid urethane foam especially in such efforts,
It is important to improve the gas thermal conductivity of the gas component in the bubbles, and especially it is essential to use trichlorofluoromethane (hereinafter referred to as R-11) as a blowing agent and fill the foam bubbles with R-11 gas. Met.

However, avoid the phenomenon that the moisture contained in the raw material system reacts with the isocyanate due to the residual moisture in the urethane foam raw material or the moisture absorption at the time of injecting it into the heat insulation box, and the generated carbon dioxide gas is contained in the foam bubbles. I couldn't. The gas thermal conductivity of R-11 is 0.0067kcal / mhr
℃, the thermal conductivity of carbon dioxide is 0.0125kc
The presence of carbon dioxide gas was a major problem in improving the thermal conductivity of the foam and the thermal conductivity of the foam.

Conventionally, for the removal of carbon dioxide gas generated from the system, for example, a method disclosed in Japanese Utility Model Publication No. 53-36297 has been proposed. This Japanese Utility Model Publication No. 53-36297 is characterized in that carbon dioxide gas generated from coffee beans filled in a closed container is adsorbed and removed by molecular sieves enclosed in the closed container.

Problems to be Solved by the Invention However, for coffee beans having a filling space such as coffee beans, there is no problem because the generated carbon dioxide gas moves through the voids and is adsorbed by the molecular sieves which are carbon dioxide gas adsorbents. However, in the case of a hard urethane foam, even if a carbon dioxide gas adsorbent is embedded, since the bubbles are closed cells, the movement of carbon dioxide gas is slow and there is a problem that the carbon dioxide gas cannot be adsorbed during the period from the production to the actual use. Referring to FIG. 4, reference numeral 1 is a heat-insulating box, which is an outer box 2 made of an iron plate, an inner box 3 made of plastic, and an outer box 2.
Rigid urethane foam 4 integrally foamed between the inner box 3 and
It consists of 5 is a molecular sieve (9F made by Toyo Soda Co., Ltd.) filled in a breathable bag 6, which is previously disposed between the outer box and the inner box 3 and integrally foamed.

In such a configuration, the carbon dioxide gas contained in the bubbles is blocked by the bubble film of the rigid urethane foam 4 which is a closed cell, and there is no pressure difference between the bubble film and the molecular sieves 5, so that the diffusion rate is However, there was a phenomenon that it did not reach the molecular sieves 5 slowly and easily.

There is also a phenomenon that air having a high gas thermal conductivity, which stays in the particles of the molecular sieves 5 and between the particles, enters into the bubbles of the rigid urethane foam 4 which is negative pressure due to the adsorption of carbon dioxide gas. Therefore, the heat conductivity of the rigid urethane foam 4 could not be sufficiently improved because the carbon dioxide gas could not be completely adsorbed during the period from the production of the heat insulating box 1 to the actual use thereof.

In view of the above problems, the present invention aims at adsorbing and removing carbon dioxide gas contained in a rigid urethane foam in a short time, improving the thermal conductivity of the rigid urethane foam, and improving the heat insulating performance of a heat insulating box. And

Means for Solving the Problems In order to solve the above problems, the present invention provides a fluorocarbon-based foaming agent for a carbon dioxide adsorbent pre-wetted with a non-dissolving fluorocarbon solvent in a plastic film. A heat-insulating box body is formed by arranging a package body, which is packaged with an outer cover made of a plastic film that is dissolved or swollen by a compound, between an inner box and an outer box and integrally foamed with a rigid urethane foam.

Action With the above configuration, the outer cover of the package filled with the carbon dioxide adsorbent is subjected to a chemical action such as dissolution or swelling by the fluorocarbon gas in the bubbles of the rigid urethane foam, and the outer cover is cracked, pinholes, etc. Occurs. Only from this point, the adsorption action of the carbon dioxide adsorbent begins. Thus, the carbon dioxide gas contained in the rigid urethane foam is easily adsorbed. In this case, the rate of movement of the carbon dioxide gas is determined by the passage of the heat insulating wall of the rigid urethane foam, but since the inside of the package of the carbon dioxide gas adsorbent has a negative pressure, it can be moved in a short time. Further, the adsorbent is pre-wet with a chlorofluorocarbon solvent, without releasing air or the like instead when adsorbing carbon dioxide gas in the rigid urethane foam, and because the chlorofluorocarbon solvent diffuses into the rigid urethane foam, The heat insulation performance and strength of the rigid urethane foam are not deteriorated.

Examples Hereinafter, the heat insulating box body of the present invention will be described with reference to FIGS. 1 to 3 by way of examples. It should be noted that the same components as those of the related art are denoted by the same reference numerals and the description thereof will be omitted.

7 is a package in which synthetic zeolite is packaged as the carbon dioxide adsorbent 8, and the jacket 9 of the package is a biaxially oriented polystyrene film. The carbon dioxide adsorbent 8 is previously moistened with a fluorocarbon solvent (not shown), dibromotetrafluoroethane.

The packaging body 7 is fixed to the back surface of the inner box 3 with an adhesive tape or the like, and the space between the inner box and the outer box 2 is integrally foamed with a hard urethane foam 4 having a freon 11 as a foaming agent to form a heat insulating box body 1. are doing.

The heat-insulating box 1 obtained was dismantled immediately after foaming, and 4
When dismantled after a week, the thermal conductivity of the rigid urethane foam 4 has decreased from 0.0135 kcal / mhr ° C to 0.0120 kcal / mhr ° C, indicating that the heat insulation performance of the heat insulation box 1 has improved by about 10%. understood. The thermal conductivity was measured at an average temperature of 24 ° C using K-MATIC manufactured by Vacuum Riko Co., Ltd.

As described above, it was found that the heat insulating box 1 of the present invention exhibits excellent heat insulating performance. This is because the carbon dioxide gas generated by the residual water in the raw material of the rigid urethane foam or the moisture due to the moisture absorption at the time of integral foaming reacting with the isocyanate as the curing agent is filled in the package 7 without remaining in the rigid urethane foam 4. The carbon dioxide gas adsorbent 8 thus adsorbed and removed. In the adsorption process, the carbon dioxide gas in the hard urethane foam 4 is absorbed by the foaming agent in the hard urethane foam through the cracks / pinholes formed in the outer cover 9 due to the chemical attack, and the carbon dioxide gas filled in the package 7 is absorbed. Reach Agent 8. In particular, carbon dioxide adsorbent 8 has a vapor pressure at 25 ° C. of 0.47 kg / cm ^2, which is considerably lower than atmospheric pressure, and is wet with a fluorocarbon solvent (not shown), dibromotetrafluoroethane, so that the carbon dioxide adsorption rate is remarkable. The carbon dioxide gas is rapidly adsorbed and instead diffuses into the rigid urethane foam 4 without releasing a gas having a high thermal conductivity such as air. Dibromotetrafluoroethane has an excellent gas thermal conductivity of 0.0060 kcal / mh ° C. and does not deteriorate the heat insulation performance of the rigid urethane foam.

Although synthetic zeolite is used as the carbon dioxide adsorbent 8 in the examples, metal oxides, metal hydroxides, activated carbon, silica gel and the like are also possible. Although a biaxially stretched polystyrene film is used as the jacket 9, an unstretched polystyrene sheet, a methyl methacrylate sheet or the like may be used. Furthermore, the entire surface of the jacket 9 does not have to be a plastic film that is chemically attacked by the foaming agent, and if there is a surface that does not face the hard urethane foam, a material that is inert to the foaming agent can be applied to that surface. Is.

Although dibromotetrafluoroethane was used as the Freon solvent 9, the same effect was obtained with trichlorotrifluoroethane having an equivalent vapor pressure (reference, vapor pressure (25 ° C): dibromotetrafluoroethane 0.47 kg / c
m ² , trichlorotrifluoroethane 0.45 kg / cm ² ).

Effects of the Invention As described above, a package covered with an outer cover made of a plastic film that dissolves or swells a carbon dioxide adsorbent pre-wetted with a non-dissolving Freon solvent in a plastic film, The carbon dioxide gas remaining in the rigid urethane foam is chemically attacked by the CFC-based foaming agent because it is placed between the box and the outer box, and it is integrally foamed with rigid urethane foam to form a heat-insulating box. Since it is adsorbed to the carbon dioxide adsorbent in the package, which has a negative pressure through the cracks and pinholes on the outer casing, the adsorption speed is extremely fast, and the carbon dioxide adsorbent absorbs gases such as air and moisture. Since the gas of the CFC solvent diffuses into the bubbles of the rigid urethane foam without being released, the thermal conductivity of the gas in the bubbles is reduced and the thermal conductivity of the rigid urethane foam is improved. Further, the low temperature strength is improved and a strong heat insulating box having excellent heat insulating performance can be provided.

Further, in the above-mentioned package, the carbon dioxide gas adsorbent does not adsorb outside air, moisture, etc. unless the outer cover is damaged by contact with the fluorocarbon foaming agent. Therefore, even if the rigid urethane foam is placed between the inner box and the outer box and left unfoamed, the heat insulation box body can be provided with extremely good workability without lowering the adsorption performance of the carbon dioxide gas adsorbent. is there.

[Brief description of drawings]

1 is an external perspective view of a heat insulating box body according to an embodiment of the present invention, FIG. 2 is a sectional view of the heat insulating box body, FIG. 3 is an enlarged sectional view of FIG. 2, and FIG. It is sectional drawing of a heat insulation box. 1 ... Insulation box, 2 ... Outer box, 3 ... Inner box, 4 ... Hard urethane foam, 7 ... Package.

Claims (2)

[Claims] 1. A carbon dioxide adsorbent, an outer cover made of a plastic film that dissolves or swells in a fluorocarbon foaming agent, an inner box, an outer box, and a rigid urethane foam filled between the boxes. A carbon dioxide adsorbent is pre-wetted with a non-soluble CFC solvent in the jacket, and then a package packaged in the jacket is placed between the inner box and the outer box. . 2. The heat insulating box according to claim 1, wherein a freon selected from dibromotetrafluoroethane and trichlorotrifluethane is used as the freon solvent.