JPH0796528A - Production of heat insulating box object - Google Patents

Abstract

PURPOSE:To eliminate the dangerousness of explosion by foaming a foamable heat insulating material while supplying inert gas from the gas vent part provided to a jig. CONSTITUTION:A box object consisting of inner and outer boxes 1,2 is arranged in a jig 3 and a hard urethane foam raw material containing cyclopentane as a foaming agent is injected into the box object from an injection port 4 and foamed to fill the box object with a heat insulating material 5. A gas vent part 6 for removing existing air and the foaming agent generated as gas to the outside of the jig 3 is provided to the foaming and filling final part of the outer box 2 and the jig 3. When the hard urethane foam raw material is injected in the gap part between the inner and outer boxes 1,2 from the injection port 4, a part of the air and foaming agent preliminarily present in the gap part is leaked to the outside from the gas vent part 6. At this time, by supplying nitrogen gas from a gas supply port 7, the conc. of cyclopentane can be suppressed to 1.4% or less of a lower explosion limit and the concn. of oxygen in the circumferential atmosphere is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat insulating box used for a refrigerator, a freezing prefab or the like.

[0002]

2. Description of the Related Art In recent years, chlorofluorocarbons (hereinafter C
Environmental problems such as ozone depletion and global warming due to the influence of FC) are drawing attention. From such a viewpoint, reduction of the amount of CFC used as a foaming agent has become an extremely important theme.

Therefore, in a typical urethane foam, which is a heat insulating foam material, a hydrocarbon is used as a foaming agent which does not contain halogen in the molecule, has no ozone layer depletion, and has very little effect on global warming. Proposed to be used.

For example, Japanese Unexamined Patent Publication (Kokai) No. 3-152160 describes a method for producing a polyurethane rigid foamed plastic using a flammable substance such as cyclopentane or cyclohexane, which is a hydrocarbon, as a foaming agent.

An example of a conventional method for manufacturing a heat insulating box will be described below with reference to FIG. Reference numeral 1 is an inner box formed of ABS resin or the like, and 2 is an outer box formed of a metal plate or the like. The box body formed by the inner box 1 and the outer box 2 is installed in the jig 3, and the hard urethane foam raw material having hydrocarbon as a foaming agent is injected from the injection port 4, the heat insulating material 5 is foam-filled, and the heat insulating box is formed. Manufacture the body. The outer box 2 and the portion of the jig 3 that corresponds to the final portion of the foam filling are provided with a gas vent 6 for removing the existing foaming agent generated as air or gas to the outside of the jig for the purpose of improving the filling property. It is provided.

[0006]

However, in the above-mentioned case, the gasified foaming agent leaked from the gas vent 6 is accumulated around the jig 3. Since the foaming agent, hydrocarbon, is flammable, there is a risk of ignition and explosion during manufacturing if the lower limit concentration of explosion is exceeded. Therefore, it is an object to establish a safe method for manufacturing a heat insulating box without danger of explosion even when manufacturing a heat insulating box using hydrocarbon as a foaming agent.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a foamed heat insulating material while supplying an inert gas or forcibly exhausting the gas from a gas vent provided in a jig. By foaming, there is provided a safe manufacturing method which is free from the risk of explosion even during manufacturing of the heat insulating box.

[0008]

According to the above-described manufacturing method, the gasified foaming agent leaks from the gas venting portion because it foams while supplying the inert gas or forcibly exhausting the gas from the gas venting portion provided in the jig. Is rarely dispersed by the inert gas and does not exceed the lower limit concentration of explosion, and further, the oxygen concentration is reduced by the inert gas, and it is outside the explosion region. In addition, forced exhaust allows direct discharge to a safe place, and the flammable gas does not stay in high concentration around the jig. Therefore, it is possible to provide a safe manufacturing method in which there is no danger of explosion even when manufacturing the heat insulating box.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 1 is an inner box formed of ABS resin or the like, and 2 is an outer box formed of a metal plate or the like. The box body formed by the inner box 1 and the outer box 2 is installed in the jig 3, and the rigid urethane foam raw material having cyclopentane as a foaming agent is injected from the injection port 4, the heat insulating material 5 is foam-filled, and the heat insulating box is formed. Manufacture the body. In addition, a gas vent 6 for removing existing air and a foaming agent generated as gas to the outside of the jig is provided at a portion of the outer box 2 and the jig 3 corresponding to the final portion of the foam filling. In addition, a gas supply port 7 for nitrogen, which is an inert gas, is provided in the vicinity of the gas venting portion 6 so that nitrogen gas can be supplied from the gas supply port 7 during foaming of the urethane foam.

Next, the foaming behavior after injecting the rigid urethane foam raw material will be described. From the inlet 4, the hard urethane foam raw material is injected into the space between the inner box 1 and the outer box 2 to start foaming and fill the space. At this time, a part of the air and the foaming agent existing in the void portion leaks to the outside of the refrigerator through the gas vent portion 6. Normally, the gas vent 6
The cyclopentane concentration in the surrounding area rises to around 2%, which exceeds the explosion lower limit of 1.4%.
By supplying nitrogen gas from the above, the cyclopentane concentration can be suppressed to the explosion lower limit of 1.4% or less, and the oxygen concentration in the surrounding atmosphere is reduced, so that an atmosphere that does not explode does not occur. Therefore, according to the heat insulating box manufacturing method of the present invention, there is no risk of explosion even during the manufacturing of a heat insulating box body using a hard urethane foam having a flammable hydrocarbon as a foaming agent, and it can be produced safely. it can.

If the jig, the inner box, and the outer box are cooled by the nitrogen gas supplied, the performance of the heat insulating material is affected. Therefore, in order to prevent cooling, the heating temperature should be equal to the jig heating temperature. Further effects can be obtained by supplying the heated nitrogen gas.

Further, by forcibly exhausting the gas from the air supply port, cyclopentane can be directly discharged to a safe place, and the combustible gas does not stay in a high concentration around the jig. In addition to obtaining the effect of, there is no nitrogen consumption and rational production is possible.

[0014]

As described above, according to the method for manufacturing a heat insulating box according to the present invention, the foamed heat insulating material is foamed while the inert gas is being supplied from the gas venting portion provided in the jig. The gasified foaming agent leaking from the part is rarely dispersed by the inert gas, does not exceed the lower limit concentration of explosion, and further, the oxygen concentration is reduced by the inert gas, and becomes outside the explosion region. In addition, forced exhaust allows direct discharge to a safe place, and the flammable gas does not stay in high concentration around the jig. Therefore, it is possible to provide a safe manufacturing method in which there is no danger of explosion even when manufacturing a heat-insulating box body to which a hard urethane foam having hydrocarbon as a foaming agent is applied.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a heat insulating box and a jig in a conventional example.

[Explanation of symbols]

 1 Inner box 2 Outer box 3 Jig 5 Heat insulating material 6 Gas vent 7 Air supply port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomonao Tenra 3-22 Takaidahondori, Higashiosaka City, Osaka Prefecture Matsushita Refrigerating Machinery Co., Ltd.

Claims (3)

[Claims] 1. A box body having a void between an outer box and an inner box is installed in a jig, and a foamed heat insulating material such as pentane or cyclopentane as a foaming agent is injected into the void. A method for manufacturing a heat-insulating box in which a foamed heat-insulating material is foamed while supplying an inert gas from a degassing portion provided in a jig in the heat-insulating box formed by foaming. 2. A box body having a void between an outer box and an inner box is installed in a jig, and a foamed heat insulating material such as pentane or cyclopentane as a foaming agent is injected into the void. A method for manufacturing a heat insulating box, which comprises foaming a foamed heat insulating material while supplying heated inert gas from a degassing portion provided in a jig in the heat insulating box formed by foaming. 3. A box body having a space between an outer box and an inner box is set in a jig, and a foamed heat insulating material such as pentane or cyclopentane as a foaming agent is injected into the space. A method for manufacturing a heat insulating box, which comprises foaming a foamed heat insulating material while forcibly discharging gas from a gas venting portion provided in a jig in the heat insulating box made of foam.