JPH04217774A - Heat insulating box body - Google Patents

Abstract

PURPOSE:To suppress deterioration with a time of heat insulating performance by a method wherein ABS the constituting component of which is especially limited is used for an inner box, in a heat insulating box body, e.g. a refrigerator, a freezer, formed by using a foamed heat insulating material, e.g. a rigid urethane foam. CONSTITUTION:A heat insulating box body comprises a rigid urethane foam 4 formed through water-foaming and an inner box 5 formed such that an ABS resin composition prepared by polymerizing a monomer mixture of 57-63wt.% vinyl cyanide compound and 37--43wt.% am aromatic vinyl compound under the presence of 14-19 wt pts conjugate synthetic rubber is shaped.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating box for refrigerators, freezers, etc., which is made of a foamed heat insulating material such as rigid urethane foam.

0002

[Prior Art] Generally, insulating boxes for refrigerators and the like are made by injecting raw materials for a foamed insulation material such as rigid urethane foam into the space formed by combining an inner box and an outer box. It is formed by foaming.

[0003] ABS resin has been mainly used for the inner box of the insulating box. Here, 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. That is, the content of vinyl cyanide compound in the graft copolymer is 60 to 90.
It refers to a resin composition in which a vinyl cyanide compound and an aromatic vinyl compound copolymer are mixed in the same amount by weight.

0004

[Problem to be solved by the invention] When such a rigid urethane foam is used as a foam insulation material for a heat insulation box, at the beginning, CO2 sufficiently fills the bubbles, and the foam thermal conductivity is low. , showing stable insulation performance.

[0005] However, CO2 has an extremely large gas diffusion coefficient, and over time passes through the plastic inner box to the outside of the insulating box, and air, which has a high gas thermal conductivity, enters and rapidly There was a problem that the insulation performance deteriorated. To explain this conventional method with reference to FIG. 3, reference numeral 1 denotes an insulating box body, which is composed of an outer box 2 made of an iron plate, an inner box 3 made of ABS resin, and a rigid urethane foam 4 formed integrally between the two boxes. . The inner box 3 is made of general-purpose ABS resin. General-purpose ABS resin is made of 1 in the presence of conjugated diene synthetic rubber.
A graft copolymer obtained by polymerizing a monomer mixture of 0 to 40% by weight of a vinyl cyanide compound and 60 to 90% by weight of an aromatic vinyl compound, that is, a vinyl cyanide compound and an aromatic vinyl compound are added to the graft copolymer. A resin composition mixed with a copolymer.

The rigid urethane foam 4 uses CO2, which is generated by the reaction between water and isocyanate, as a blowing agent.

[0007] In such a configuration, CO
2 diffuses from the insulating box 1 through the inner box 3, and the insulating box 1
There will be more air intrusion. As a result, there was a problem in that the heat insulation performance of the heat insulation box 1 deteriorated rapidly.

[0008] The present invention solves the conventional problems.
It is an object of the present invention to provide a heat insulating box having a heat insulating performance that is stable over time.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the insulating box of the present invention comprises an outer box, a rigid urethane foam using CO2 generated by the reaction of water and isocyanate as a blowing agent, and a conjugated diene foam. 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 is polymerized in the presence of 14 to 19 parts by weight of a synthetic rubber, that is, a graft copolymer. A heat insulating box body consisting of an inner box made of a high nitrile ABS resin composition mixed with a vinyl cyanide compound and an aromatic vinyl compound copolymer having a vinyl cyanide compound content of 37 to 43% by weight in the polymer. It is something that forms.

[0010] Here, as the vinyl cyanide compound, acrylonitrile can be used, and as the aromatic vinyl compound, styrene or the like can be used.

[0011]

[Function] The above structure allows C in hard urethane foam to
Although O2 has a large gas diffusion coefficient and high resin permeability, a high nitrile ABS resin composition with a dense molecular structure and high gas barrier properties is used for the inner box material. The diffusion of CO2 outside the insulated box is extremely small, and the intrusion of air from the inner box is also reduced. Therefore, it exhibits stable heat insulation performance over time.

[0012] Furthermore, 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 for a heat insulating box.

[0013] In this way, it is possible to provide a heat insulating box with excellent heat insulating performance over a long period of time.

[0014]

[Example] The following is an example of the present invention shown in Figs.
This will be explained using FIG. 2. Note that components having the same configuration as the conventional one are designated by the same numbers and the description thereof will be omitted.

[0015]

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 is melted into a flat plate using an extruder equipped with a coat hanger die. This is processed and molded using a vacuum molding machine.

After fitting the inner box 5 into the outer box 2, as shown in Table 1, the inner box 5 and the outer box are filled with urethane raw material using CO2 generated by the reaction of water and isocyanate as a foaming material. Inject and fill between both boxes of 2 and hard urethane foam 4
The heat insulating box body 6 is obtained.

Table 1 shows the appearance of the flat plate during vacuum forming of the inner box and 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 rigid urethane foam 4 filled in the insulating box 6 was sampled from the insulating box 6 at 1 day and 540 days after foaming, and the results are also shown in Table 1. Ta.

As a comparative example, the results of using inner boxes made of ABS resin compositions having different compositions are also shown in Table 1 (Comparative Examples A to D).

As described above, the heat insulating box 6 of the present invention maintains stable heat insulating performance over a long period of time, and the inner box 5
There are no problems with the quality of the product, and it can be easily and stably put on the market.

As can be seen from the Examples and Comparative Examples, when CO2 generated by the reaction between water and isocyanate is applied to the rigid urethane foam 4 as a blowing agent, the composition ratio of acrylonitrile in the monomer mixture changes after 540 days. , high nitrile A made from 57% or more by weight
It was found that if the inner box 5 was not made of a BS resin composition, the thermal conductivity would be significantly degraded. This is because the molecular structure of the ABS resin composition that forms the inner box 5 becomes denser, and the diffusion of CO2 in the rigid urethane foam 4 is controlled and the intrusion of air is reduced. This is because there is no deterioration in thermal conductivity.

[0022] If the composition ratio of acrylonitrile exceeds 63% by weight and the conjugated diene rubber component falls below 14%,
Cracks occur due to poor vacuum formability of the inner box 5 and poor crack resistance when fitted into the outer box 2, which poses a major problem in ensuring the quality of the inner box 5.

[0023] As described above, the thermal conductivity deteriorates little over time, stable thermal conductivity is obtained over time, and there is no problem in terms of the quality of the inner box 5. is obtained.

[0024]

As described above, the present invention provides an outer case, a rigid urethane foam using CO2 generated by the reaction of water and isocyanate as a blowing agent, and a conjugated diene synthetic rubber 1.
Molding 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. Because it is an insulated box body consisting of an inner box with high resin permeability, even if CO2 generated by the reaction between water and isocyanate is applied as a blowing agent, the diffusion to the outside of the inner box is small. Air intrusion can also be suppressed.

As a result, the thermal conductivity of the rigid urethane foam shows little deterioration over time, making it possible to provide a heat insulating box that can maintain stable heat insulating performance over a long period of time. Further, the inner box has no problems in vacuum formability or crack resistance, and can maintain excellent appearance quality.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a heat insulating box according to an embodiment of the present invention.

[Fig. 2] A cross-sectional view of a heat insulating box showing an embodiment of the present invention.

[Figure 3] Cross-sectional view of a conventional heat-insulating box

[Explanation of symbols]

2 Outer box 4 Rigid urethane foam 5 Inner box 6　　　　　　　　Insulated box body

Claims (1)

[Claims] Claim 1: An outer box, a rigid urethane foam using CO2 generated by the reaction of water and isocyanate as a blowing agent, and 57 to 63 parts by weight of cyanide in the presence of 14 to 19 parts by weight of conjugated diene synthetic rubber. A heat insulating box body comprising an inner box made of a high nitrile ABS resin composition obtained by polymerizing a monomer mixture of a vinyl compound and an aromatic vinyl compound in an amount of 37 to 43% by weight.