JPH04184075A - Thermal insulating box - Google Patents

Abstract

PURPOSE:To improve a heat transfer rate of a hard urethane foam and further improve a thermal insulating performance of a thermal insulating box by a method wherein the thermal insulating box is comprised of an outer box, the hard urethane foam containing carbonic acid gas adsorption agent and having as foam agent substance 1,1-dichloro 1-fluoroethane (HCFC-1416) and an inner box molded by high nitrile ABS resin compound. CONSTITUTION:A thermal insulation box is comprised of an outer box 2, a hard urethane foam 4 containing carbonic acid gas adsorption agent, and an inner box 5 molded by a high nitrile ABS resin compound got through a polymerization of monomer mixture of a vinyl cyanide compound with 57 to 63wt% and aromatic vinyl compound with 37 to 43wt% under a conjugated diene synthetic rubber with 14 to 19wt%. Carbonic acid gas contained in the hard urethane foam can be removed with carbonic acid gas adsorption agent and at the same time since high nitrile ABS resin compound having minute molecular structure with a hard gas permeability is used as the inner box material, its air permeability is low. In addition, since it has a high chemical resistance against HCFC-141b, no cracks are generated and no immersion of air through the cracks and it shows a superior thermal insulating performance in view of aging characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat insulating box for use in refrigerators, freezers and the like.

BACKGROUND OF THE INVENTION In recent years, from the viewpoint of energy conservation, it has been strongly desired to reduce the thermal conductivity of foam insulation materials and improve their insulation performance.

For this reason, in the production of rigid urethane foam, which is a typical foam insulation material, polyether polyol used as the main raw material and polyisocyanate-1 auxiliary raw material and
Various efforts have been made to improve the foam stabilizers, catalysts, and blowing agents used in the production of foams from the viewpoint of raw materials. In such efforts, especially to reduce the thermal conductivity of rigid urethane foam,
It is important to improve the gas thermal conductivity of the gas components in the bubbles. In particular, it is essential to use 1,1-dichloro-1-fluoroethane (hereinafter referred to as HCFC-141b) as a blowing agent, which does not cause environmental problems due to ozone layer depletion and has low gas thermal conductivity, to fill the bubbles with gas. It is.

However, there is a phenomenon in which the residual moisture in the urethane foam raw material and the water vapor that permeates through the face material of the insulating box react with the incyanate raw material and the remaining unreacted incyanate, and the generated carbon dioxide gas is contained in the foam bubbles. could not be avoided. That is, the gas thermal conductivity of HCFC-141b is 0.0095 W/mK (0,00821
al/mhc), whereas the thermal conductivity of carbon dioxide is 0
, 0163 W/mK (0,01401 al/mhc
, :l, and the existence of carbon dioxide gas generated was a major problem in improving the gas thermal conductivity and improving the thermal conductivity of the foam.

Conventionally, for removing carbon dioxide gas generated from the system, a method as disclosed in, for example, Japanese Unexamined Patent Publication No. 57-49628 has been proposed. To explain this Japanese Patent Application Laid-open No. 57-49628, a carbon dioxide adsorbent is added to a urethane raw material and foamed to produce a urethane foam, which adsorbs and removes carbon dioxide gas generated in the system. It is characterized by

Problems to be Solved by the Invention However, when such urethane foam is used as a heat insulating material for a heat insulating box, the carbon dioxide gas in the bubbles is adsorbed and removed in the initial stage, so the thermal conductivity is low and excellent heat insulating performance is not achieved. However, on the other hand, as the pressure in the bubbles decreases, air penetrates through the plastic inner box material of the heat insulating box, causing a problem in that the heat insulating performance deteriorates rapidly over time.

Referring to FIG. 3, numeral 1 is a heat insulating box body which is composed of an outer box 2 made of iron plate, an inner box 3 made of ABS resin, and a hard urethane foam 4 integrally foamed between the two boxes. The inner box 3 is made of general-purpose ABS resin. General-purpose ABS resin is obtained by polymerizing a monomer mixture of 10 to 40% by weight of vinyl cyanide compound and 60 to 90% by weight of aromatic vinyl compound in the presence of conjugated diene synthetic rubber, i.e. It refers to a resin composition in which a vinyl cyanide compound and an aromatic vinyl compound copolymer having a vinyl cyanide compound content of 60 to 90% by weight are mixed in a graft copolymer.

Furthermore, the hard urethane foam 4 containing HCFC-141b as a blowing agent component contains a carbon dioxide adsorbent made of synthetic zeolite powder that has been added to the urethane raw material in advance and dispersed in the bubbles during the foaming process.

In such a configuration, the carbon dioxide contained in the bubbles is adsorbed and removed by the carbon dioxide adsorbent made of synthetic zeolite powder, and the thermal conductivity of the rigid urethane foam 4 decreases as the gas thermal conductivity improves, resulting in improved insulation performance. will improve. but,
Over time, as carbon dioxide gas is removed, the pressure in the bubbles decreases, and more air penetrates through the inner box 3. As a result, there was a problem that the heat insulation performance of the heat insulation box 1 was deteriorated.

In addition, when HCFC-141b is used as a blowing agent component, cracks occur in the inner box 3 due to its strong chemical attack properties, which deteriorates the appearance quality and further increases air infiltration, so that the insulation performance of the insulation box 1 increases. There is a problem in that the deterioration of the thermal insulation performance is accelerated, and the challenge is to maintain excellent thermal insulation performance over time.

In view of the above problems, the present invention adsorbs and removes carbon dioxide contained in a hard urethane foam containing HCFC-141b as a blowing agent component, improves the thermal conductivity of the hard urethane foam, and prevents air from entering. The purpose is to improve the insulation performance of the insulation box.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an outer box, a hard urethane foam containing a carbon dioxide adsorbent, and 57 parts by weight of a conjugated diene synthetic rubber in the presence of 14 to 19 parts by weight. It was obtained by polymerizing a monomer mixture of ~63% by weight of vinyl cyanide compound and 37-43% by weight of aromatic vinyl compound. That is, high nitrile ABS in which a vinyl cyanide compound and an aromatic vinyl compound copolymer having a vinyl cyanide compound content of 37 to 43% by weight are mixed into a graft copolymer.
A heat insulating box body is formed with an inner box molded from a resin composition.

Here, acrylonitrile can be used as the vinyl cyanide compound, and styrene can be used as the aromatic vinyl compound.

Effect With the above structure, carbon dioxide contained in the hard urethane foam can be removed by the carbon dioxide adsorbent, and even if the pressure in the bubbles decreases by adsorbing carbon dioxide, the high nitrile foam has a dense molecular structure and is difficult for gas to permeate. Since ABS resin composition is used for the inner box material, air permeation is small, and furthermore, it has high chemical resistance to HCFC-141b, so cracks 73: do not occur through the crack + g portion.
Since there is no intrusion of foreign material, it shows excellent insulation performance over time. Further, the high nitrile ABS resin composition having the above structure can be used without problems in terms of vacuum formability, appearance quality, etc. required as an inner box material of a heat insulating box. In this way, it is possible to provide a heat insulating box with excellent heat insulating performance over a long period of time.

Examples Below, examples will be given to illustrate the heat insulating box of the present invention in Figures 1 to 2.
This will be explained using figures. Incidentally, those having the same configuration as the conventional one are denoted by the same numbers and the description thereof will be omitted.

5 is an inner box, and as shown in Table 1, a high nitrile ABS resin composition containing acrylonitrile as a vinyl cyanide compound and styrene as an aromatic vinyl compound as monomers is extruded using a coat hanger die. It is melted and processed into a flat plate using a machine, and this flat plate is then molded using a vacuum forming machine.

After fitting this inner box 5 into the outer box 2, use a carbon dioxide adsorbent 6 (synthetic zeolite powder bundle 5A made by Thor) as shown in Table 1.
) A urethane raw material is injected and filled between the inner box 5 and the outer box 2 to produce a hard urethane foam 4 and obtain a heat insulating box body 6.

In addition, the appearance of the flat plate when the inner box is vacuum formed, the inner box 5
Table 1 shows the results regarding the presence or absence of cracks in the inner box 5 when the inner box 5 was fitted into the outer box 2. In addition, the thermal conductivity of the hard urethane foam 4 filled in the heat insulating box 6 was measured 1 day after foaming and 2 days after foaming.
Table 1 also shows the results of samples taken from the heat insulating box 6 and measured after 50 days.

As a comparative example, Table 1 also shows the results when using rigid urethane foams having different ABS resin composition raw material formulations with different composition contents (Comparative Examples A to D).

(Hereinafter referred to as margins) As described above, the heat insulating box 6 of the present invention maintains excellent heat insulating performance over a long period of time, and there is no problem with the quality of the inner box 5, making it possible to easily and stably provide the inner box 5. .

As can be seen from the Examples and Comparative Examples, when a carbon dioxide adsorbent is added to the hard urethane foam 4, initially,
Carbon dioxide gas in the bubbles is adsorbed and removed, and the thermal conductivity of the hard urethane foam 4 is small and the heat insulation performance is improved, but 25
After 0 days, it was found that the thermal conductivity deteriorated significantly unless the inner box 6 was made of a high nitrile ABS resin composition manufactured from a monomer mixture with a composition ratio of acrylonitrile of 57% by weight or more. Ta. This is because the molecular structure of the ABS resin composition that forms the inner box 6 is dense, and the intrusion of air is reduced, so the carbon dioxide gas adsorbent adsorbs and removes the carbon dioxide gas in the bubbles, reducing the pressure in the bubbles. In addition, since the inner box 5 has excellent chemical resistance against HCFC, cracks do not occur during cooling operation, and since there is no air intrusion through cracked parts, the hard urethane foam 4 There is no deterioration in thermal conductivity. In addition, the composition ratio of acrylonitrile is 64% by weight.
If the conjugated diene rubber content exceeds 13% or falls below 2.
If it exceeds 0%, cracks may occur due to poor vacuum formability of the inner box 5 and weak crack resistance when fitting it into the outer box 2, which poses a major problem in ensuring the quality of the inner box 6. be.

In this way, the deterioration of thermal conductivity over time is small, and the inner box 5
The heat insulating box body 6 having excellent quality can be obtained without any problem in terms of quality.

Effects of the Invention As described above, the present invention comprises an outer case, a hard urethane foam containing a carbon dioxide adsorbent, and a conjugated diene-based synthetic rubber 1.
A high nitrile ABS resin composition obtained by polymerizing a monomer mixture of 57 to 63% by weight of a vinyl cyanide compound and 37 to 43% by weight of an aromatic vinyl compound in the presence of 4 to 19 parts by weight is molded. Since it is an insulated box body consisting of a hard urethane inner box, carbon dioxide gas generated in the hard urethane foam can be easily adsorbed and removed. Moreover, even when carbon dioxide gas is adsorbed by the carbon dioxide adsorbent and the pressure in the bubbles decreases, it is possible to prevent air from entering from outside over time. Furthermore, there are no cracks in the inner box during cooling operation, and no air intrusion through cracks.

As a result, the thermal conductivity of the rigid urethane foam remains low over time, making it possible to provide a heat insulating box that has excellent heat insulating performance over a long period of time and is free from environmental problems. Moreover, the inner box has no problems in vacuum formability or crack resistance, and can maintain excellent appearance quality.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view of a heat insulating box according to an embodiment of the present invention, Fig. 2 is a sectional view of the same heat insulating box, and Fig. 3 is a sectional view of a conventional heat insulating box. It is. 2...Outer box, 4...Hard urethane foam, 5...Inner box, 6...Insulating box body. Name of agent: Patent attorney Akira Okaji and two others

Claims (1)

[Claims] Contains an outer box and a carbon dioxide adsorbent, and contains 1,1-dichloro1
- Rigid urethane foam containing fluoroethane as a blowing agent component, and 57 to 63% by weight of a vinyl cyanide compound in the presence of 14 to 19 parts by weight of conjugated diene synthetic rubber;
A heat insulating box body comprising an inner box molded from a high nitrile ABS resin composition obtained by polymerizing a monomer mixture with 43% by weight of an aromatic vinyl compound.