JPH094968A - Thermally insulating material - Google Patents

Abstract

PURPOSE: To provide a thermally insulating material that is prevented from the permeation of carbon dioxide gas contained in the bubbles of the thermally insulating material and deformation of the thermally insulating material, in the thermally insulating box body that is used for a refrigerator and a showcase. CONSTITUTION: A polyvinylidene chloride sheet 6 is joined to a part of a thermally insulating box body, that is plastic inner box 2. The polyvinylidene chloride sheet 6 has a better gas barrier characteristic. The space part 4 of it is filled with a thermally insulating material 5. Therefore, the poly-vinylidene chloride sheet 6 lies between the thermally insulating material 5 and the plastic inner box 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulator used in refrigerators, showcases and the like.

[0002]

2. Description of the Related Art A conventional heat insulating box will be described with reference to FIG.

In FIG. 2, reference numeral 1 is a heat insulating box, which is constructed by filling a synthetic resin inner box 2, a synthetic resin outer box 3 and a space 4 between the boxes 2 and 3 with a foamed heat insulating material 5. ing. The heat insulating material 5 is made by mixing and foaming a polyol, an isocyanate, a foaming agent, a foam stabilizer and a catalyst (not shown). At this time, the foaming agent mixes Freon and water,
Alternatively, only water is used for foaming. Regarding the gas composition in the bubbles after foaming, the former is composed of Freon and carbon dioxide, and the latter is composed of carbon dioxide only.

Carbon dioxide has a fluorocarbon permeability of 11
Since it is 138 times larger than that of, the carbon dioxide gas 7 in the heat insulating material 5 permeates the synthetic resin inner box 2 when used for a long time, and the carbon dioxide gas 7 in the bubbles of the heat insulating material 5 decreases. ,
There is also a problem that the gas pressure is also reduced, the pressure becomes negative with respect to the atmospheric pressure, the bubbles are pushed and deformed, and the heat insulating material 5 contracts and deforms.

In order to deal with this, a metal foil tape or the like has been attached to the entire inner box to prevent the permeation of carbon dioxide gas, but the metal foil tape has been attached even to the portion where shrinkage deformation is unlikely to occur. Therefore, there has been a problem that the metal foil tape material and the number of attachment steps are large.

In recent years, it has been necessary to reduce the use of freon-based foaming agents in refrigerators and the like from the viewpoint of freon regulation, and a method of foaming by mixing with water or foaming only with water is widely used.

However, in such a case, as in the example shown in FIG. 2, carbon dioxide gas permeates the synthetic resin inner box 2 for a long period of time, and the gas pressure in the bubbles of the foamed heat insulating material 5 is atmospheric pressure. A negative pressure is applied to the air bubbles, and the bubbles are pushed by the atmospheric pressure so as to shrink.

[0008]

In the conventional heat insulator having carbon dioxide gas bubbles to be solved by the present invention, the degree of permeation of carbon dioxide varies depending on the thickness of the synthetic resin plate, but in a long time, However, even though the amount is very small, carbon dioxide always penetrates the synthetic resin plate, and the heat insulating material contracts and deforms.

In view of the above problems, the present invention provides a heat insulating body having a heat insulating material which suppresses permeation of carbon dioxide gas and does not shrink and deform.

[0010]

In order to achieve the above object, the invention according to claim 1 is to fill a space formed by a pair of plates with a heat insulating material having carbon dioxide gas bubbles generated by foaming. However, a plastics layer having a gas barrier property larger than that of the synthetic resin plate is provided in close contact with the synthetic resin plate of the plate and the heat insulating material.

According to a second aspect of the invention, in the invention according to the first aspect, the plastics layer having a large gas barrier property is a plastic sheet having a large gas barrier property and is a region in which deformation easily occurs. It is configured to be attached only to.

[0012]

With the above construction, the function of the invention according to claim 1 is to increase the degree of permeation of carbon dioxide gas in the heat insulating material through the synthetic resin plate by the plastics layer having a large gas barrier property for preventing permeation of carbon dioxide gas. Suppress.

The operation of the invention according to claim 2 is as follows.
The carbon dioxide gas in the heat insulating material permeates the synthetic resin plate, and the easily deformable area of the heat insulating material or the synthetic resin plate is covered with a plastic sheet having a large gas barrier property, and the carbon dioxide gas It has the effect of suppressing permeation.

[0014]

FIG. 1 is a sectional view showing a heat insulating box of an embodiment of the present invention. The same components as those of the conventional example described in FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted. To do.

Reference numeral 6 denotes a polyvinylidene chloride sheet having a large gas barrier property, which is attached to at least one location (the location where the above contraction deformation is likely to occur) of the synthetic resin inner box 2.

Permeation of carbon dioxide gas to polyvinylidene chloride
Excess rate is 20-30cc / 100in ²/ Mil / 24h
80 ° C / 25 ° C, such as polypropylene and ABS resin
0-900cc / 100in²/ Mil / 24h / 25
It is as small as 1/40 to 1/30 as compared with atmospheric pressure at ℃.

Reference numeral 5 denotes a foaming heat insulating material filled in a space 4 consisting of a pair of a synthetic resin inner box 2 and a synthetic resin outer box 3, which contains 100% water in a foaming agent ratio. The bubbles formed by the reaction between water and isocyanate are filled with carbon dioxide gas 7 only.

Therefore, even if the plate thickness is 4 mm or more in the region cooled to -20 ° C. or less, the polyvinylidene chloride sheet 6 having a large gas barrier property is attached to the synthetic resin inner box 2 for a long time. Even during the cooling operation for a long time, the carbon dioxide gas 7 is blocked by the polyvinylidene chloride sheet 6 having a large gas barrier property, and the permeation area of the carbon dioxide gas which is going to permeate the synthetic resin inner box 2 can be reduced. It is suppressed that the light passes through the inner manufacturing box 2 and is released into the atmosphere.
Therefore, there is no problem that the gas pressure in the bubble is prevented from lowering, the gas pressure in the bubble becomes equal to or lower than the atmospheric pressure, and the heat insulating material 5 contracts and deforms as in the conventional case.

Also, since the polyvinylidene chloride sheet 6 having a large gas barrier property may be attached only in the region where shrinkage deformation is likely to occur, the amount of the polyvinylidene chloride sheet material having a large gas barrier property used and the attachment The number of attachment steps can be reduced.

In this example, a polyvinylidene chloride sheet was used as a sheet having a large gas barrier property, but the present invention is not limited to the polyvinylidene chloride sheet, and carbon dioxide gas permeation is more effective than a synthetic resin plate. Any plastic sheet having a low rate, that is, a high gas barrier property may be used. Further, it may be a layer formed of powder instead of a sheet.

[0021]

According to the present invention, in claim 1,
A plastics layer having a gas barrier property larger than that of the synthetic resin plate is provided by closely adhering between the synthetic resin plate and a heat insulating material having carbon dioxide gas bubbles filled in a space made of the synthetic resin plate. The carbon dioxide gas in the bubbles is blocked by the sheet with a large gas barrier property.
Since it suppresses the permeation of the synthetic resin plate and the release of carbon dioxide into the atmosphere, the decrease in gas pressure in the bubbles is prevented, and the heat insulating material does not contract and deform.

Further, in the invention according to the second aspect, the gas barrier sheet is attached only in an area where shrinkage deformation is likely to occur, so that the amount of gas barrier sheet material used and the number of attachment steps can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a heat insulating box according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a heat insulating box in a conventional example.

[Explanation of symbols]

1 Thermal Insulation Box 2 Synthetic Resin Inner Box 3 Synthetic Resin Outer Box 4 Space 5 Insulation 6 Polyvinylidene Chloride Sheet with High Gas Barrier (Plastic Layer with High Gas Barrier) 7 Carbon Dioxide

Claims (2)

[Claims] 1. A space formed by a pair of plates is filled with a heat insulating material having carbon dioxide gas bubbles generated by foaming, and a space between the synthetic resin plate and the heat insulating material of the plates is closely attached to the heat insulating material. A heat insulator with a plastic layer that has a greater gas barrier property than a synthetic resin plate. 2. The heat insulator according to claim 1, wherein the plastics layer having a high gas barrier property is a plastics sheet having a high gas barrier property and is attached only to an area where deformation easily occurs.