JPH0796573A - Heat-insulating box - Google Patents

Abstract

PURPOSE:To prevent THE shrinkage of a foam and keep an appearance.quality for a long term by a method wherein a rigid urethane foam loaded with a cyclopentane as a component of a foaming agent and water as an adjuvant foaming agent is foamed to be loaded between an inner box made of a high- nitrile resin composition and a metallic outer box. CONSTITUTION:A graft copolymer and a coplymer are obtained by polymerizing a monomer mixture of 30-50wt.% vinyl cyanide compound and 50-70wt.% aromatic vinyl compound in the presence of a conjugated diene synthetic rubber. A high-nitrile resin composition mixed with an acrylate rubber having 2-4C alkyl is molded into an inner box 6. The inner box 6 is coated with the coplymer obtained by polymerizing a monomer mixture of 30-50wt.% vinyl cyanide compound and 50-70wt.% aromatic vinyl compound. A rigid urethane foam 5 loaded with a cyclopentane as a foaming agent and 1 part or more water as an adjuvant foaming agent is foamed to be loaded between the inner box 6 and a metallic outer box 3.

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 body such as a refrigerator or a freezer which is made of a foamed heat insulating material such as a hard urethane foam.

[0002]

2. Description of the Related Art Generally, a heat insulating box body such as a refrigerator is prepared by injecting a raw material of a foamed heat insulating material such as a hard urethane foam into a space formed between an inner box and an outer box by combining them. , Is formed by integral foaming.

ABS resin has been mainly used for the inner box of the heat insulating box. Here, the ABS resin is a graft copolymer obtained by polymerizing a monomer mixture of 10 to 40% by weight of a vinyl cyanide compound and 60 to 90% by weight of an aromatic vinyl compound in the presence of a conjugated diene-based synthetic rubber. It means a resin composition composed of a united body.

The reason why the ABS resin has been used for the inner box of the heat insulating box is that the balance between the physical properties of rigidity and impact resistance is high, the appearance has excellent luster, and the foaming agent for hard urethane foam. With respect to, it has resistance to stress cracking. Further, since the inner box of the heat insulating box is manufactured by a thermoforming method, for example, a vacuum forming method of a flat plate of a thermoplastic resin, it is necessary that the vacuum forming can be easily performed.

Here, the structure of the heat insulating box will be described with reference to FIG. 3. In FIG. 3, 1 is a heat insulating box, and AB
It is composed of an inner box 2 made of S resin and an outer box 3 made of an iron plate. The inner box 2 is fitted and fixed in close contact with the flange 4 of the outer box 3. 5 is a hard urethane foam which uses cyclopentane as a foaming agent, and is filled between the inner box 2 and the outer box 3 by integral foaming.

[0006]

Cyclopentane, which is a foaming agent for rigid urethane foam 5, has poor compatibility with polyether polyol, which is a raw material for general-purpose rigid urethane foam, and it is used as a blowing agent in the raw material. It is difficult to add and mix a large amount.

Further, since the boiling point is extremely high at 49.3 ° C., the contribution of the reaction heat due to the urethane reaction to the vaporization of cyclopentane during urethane foaming becomes insufficient, and the foam foaming rate is greatly reduced.

Therefore, it is difficult to foam-form a urethane foam having the same foam density as conventional ones by using cyclopentane alone, and it is general to use a large amount of water together as an auxiliary foaming agent.

However, when a hard urethane foam foamed by such a raw material formulation is used for a heat insulating box, carbon dioxide gas and cyclopentane gas generated by the reaction between water and organic polyisocyanate are generated in the initial stage of foaming. , The foam of hard urethane foam is sufficiently filled and the appearance quality of the heat insulating box is good, but over time, the gas diffusion coefficient of carbon dioxide, which constitutes most of the gas in the bubbles, is extremely high. Due to their large size, most of them diffuse out of the heat insulating box through the plastic inner box in a short period of time.

On the other hand, air has an extremely small gas diffusion coefficient as compared with carbon dioxide gas, and the invasion speed of air that enters air bubbles through the inner box is very slow.

As a result, an extreme decrease in internal pressure occurs in the foam bubbles temporarily, and the urethane foam shrinks at the relatively low foam strength portion where the cells are oriented due to the flow of the urethane foam and the like, resulting in heat insulation. There is a problem that the outer appearance of the box is deformed.

The present invention solves such a problem, and even when a rigid urethane foam containing cyclopentane as a foaming agent is applied to a heat insulating box, the heat insulating box keeps the appearance quality equivalent to the initial foaming with time. It is intended to provide the body.

In order to solve the above problems, the heat insulating box according to the present invention comprises a vinyl cyanide compound of 30 to 50% by weight and a vinyl cyanide compound of 50 to 50% by weight in the presence of a conjugated diene synthetic rubber.
A graft copolymer obtained by polymerizing a monomer mixture of 70% by weight of an aromatic vinyl compound, a vinyl cyanide compound of 30 to 50% by weight, and an aromatic vinyl compound of 50 to 70% by weight. A copolymer obtained by polymerizing the monomer mixture, 30 to 50% by weight of a vinyl cyanide compound, and 50 to
Copolymers obtained by polymerizing a monomer mixture with 70 wt% of an aromatic vinyl compound are coated with 2 to 4 carbon atoms
1 part of water as a foaming agent and cyclopentane as a foaming agent between the inner box formed by molding the high nitrile resin composition mixed with the acrylate rubber having an alkyl group and the metal outer box. The heat-insulating box body is formed by foaming and filling the hard urethane foam added above.

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

As the acrylate rubber having an alkyl group having 2 to 4 carbon atoms, ethyl acrylate, n-
Propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-
Butyl acrylate or the like can be used.

[0015]

With the above structure, the inner box of the heat insulating box made of the high nitrile resin composition has an extremely high gas barrier property because it has a precise molecular structure, excellent chemical resistance and low resin solubility. .

Therefore, the heat-insulating box body using the inner box having the above-mentioned structure suppresses the diffusion of carbon dioxide gas having a large gas diffusion coefficient from the hard urethane foam to the outside of the heat-insulating box body, and causes a decrease in the internal pressure of the urethane foam. Therefore, the appearance quality of the excellent heat insulating box can be maintained for a long period of time without causing the external appearance deformation of the heat insulating box due to the shrinkage at room temperature over time.

Further, since the high nitrile resin composition having the above-mentioned constitution has a sufficient vacuum forming property and various physical properties required for the inner box material of the heat insulating box, it can be applied without any problem in the manufacturing process and product quality. Is possible.

[0018]

The heat insulating box of the present invention will be described below with reference to FIGS. 1 and 2. It should be noted that the same components as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted.

[0019]

[Table 1]

The high nitrile ABS resin composition whose composition is shown in Table 1 is melted by an extruder equipped with a coat hanger die to be processed into a flat plate, and the flat plate is formed by a vacuum forming machine to form an inner box 6.

The urethane raw materials are also shown in Table 1 in the same manner. After the inner box 6 is fitted into the outer box flange 4, the urethane prescription is injected between the inner box 6 and the outer box 3. Filled to form hard urethane foam 5, heat insulation box 7
Is getting The heating temperature condition of the inner box 6 and the outer box 3 at the time of filling is 40 to 60 ° C.

It should be noted that the appearance of the heat-insulating box body is not deformed after being left at room temperature for a long period of time, the appearance of the vacuum forming, the inner box 6 and the outer box flange 4
The results regarding the presence or absence of cracks in the inner box 6 when fitted in are also shown in (Table 1).

As a comparative example, the results of the inner box characteristics of the high nitrile resin compositions having different composition contents and the presence / absence of appearance deformation of the heat insulating box body formed of the inner boxes after being left at room temperature for a long time are also shown ( Comparative Examples AD).

As described above, the heat-insulating box 7 of the present invention has a quality that does not have any problems with respect to vacuum formability, impact resistance at room temperature, and stress crack resistance. It has been found that excellent quality with no problem in appearance deformation can be obtained.

As can be seen from Examples and Comparative Examples, a monomer mixture of 30 to 50% by weight of a vinyl cyanide compound and 50 to 70% by weight of an aromatic vinyl compound is polymerized in the presence of a conjugated diene-based synthetic rubber. The graft copolymer thus obtained and 3
Excellent chemical resistance synthesized from a copolymer obtained by polymerizing a monomer mixture of 0 to 50% by weight of a vinyl cyanide compound and 50 to 70% by weight of an aromatic vinyl compound, and a special acrylate rubber. In the case of a high nitrile resin composition, the vacuum moldability and other inner box characteristics are satisfactory without any problems, and the diffusion of carbon dioxide gas that permeates through the inner box 6 is greatly suppressed, and the urethane foam It is possible to prevent external deformation of the heat insulating box due to shrinkage.

Therefore, it is possible to provide a heat-insulating box having excellent appearance quality for a long time even if it is a heat-insulating box made of a rigid urethane foam containing cyclopentane as a foaming agent.

[0027]

As described above, the present invention provides a monomer mixture of 30 to 50% by weight of a vinyl cyanide compound and 50 to 70% by weight of an aromatic vinyl compound in the presence of a conjugated diene-based synthetic rubber. A graft copolymer obtained by polymerization, 30 to
50% by weight vinyl cyanide compound and 50-70% by weight
Of the copolymer obtained by polymerizing the monomer mixture with the aromatic vinyl compound, and a monomer mixture of 30 to 50% by weight of the vinyl cyanide compound and 50 to 70% by weight of the aromatic vinyl compound. Between the inner box formed by molding the high nitrile resin composition mixed with the acrylate rubber having a C2-4 alkyl group coated with the copolymer obtained by polymerization and the outer box made of metal Since a heat-insulating box body is formed by foam-filling cyclopentane as a foaming agent and hard urethane foam to which 1 part or more of water is added as an auxiliary foaming agent, hard urethane foam using cyclopentane having a large amount of water added as a foaming agent It is possible to provide a heat-insulating box body that is capable of maintaining the appearance quality immediately after foaming for a long period of time without causing the appearance deformation due to shrinkage of the heat-insulating box body over time.

Further, since the inner box has both the vacuum formability and various physical properties required as the inner box material of the heat insulating box, it can be applied without any problem in the manufacturing process and product quality.

[Brief description of drawings]

FIG. 1 is a perspective view in which a part of a heat insulating box according to an embodiment of the present invention is cut away.

FIG. 2 is a cross-sectional view of a heat insulation box body according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional heat insulation box.

[Explanation of symbols]

 2 Outer box 5 Rigid urethane foam 6 Inner box 7 Insulation box

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29K 105: 04 C08L 75:04 (72) Inventor Hideo Nakamoto 3 Takaidamoto-dori, Higashiosaka-shi, Osaka 22-chome Matsushita Cold Machinery Co., Ltd.

Claims (1)

[Claims] 1. 30 to 5 in the presence of a conjugated diene-based synthetic rubber
Graft copolymer obtained by polymerizing a monomer mixture of 0 wt% vinyl cyanide compound and 50 to 70 wt% aromatic vinyl compound, 30 to 50 wt% vinyl cyanide compound and 50 to A copolymer obtained by polymerizing a monomer mixture with 70% by weight of an aromatic vinyl compound;
A copolymer obtained by polymerizing a monomer mixture of 50% by weight of a vinyl cyanide compound and 50 to 70% by weight of an aromatic vinyl compound is coated with an acrylate rubber having an alkyl group having 2 to 4 carbon atoms. Cyclopentane as a foaming agent and water as an auxiliary foaming agent were placed between the inner box formed by molding the mixed high nitrile resin composition and the outer box made of metal.
A heat-insulating box body made by foaming and filling a rigid urethane foam that is added in parts or more.