JPH06213561A - Insulating material and refrigerator using the same - Google Patents

Abstract

PURPOSE:To largely reduce thermal conductivity under a specific degree of vacuum by using continuous bubble formed body for an insulating meterial for a refrigerator. CONSTITUTION:A core material is comprised of compressed hard polyurethane foam 4a including continuous bubbles formed from flat bubbles having a thickness of 0.04mm or less and the core material is covered with a container 5 comprising a film having gas barrier property so that the pressure of the interior thereof is reduced to seal the container, thereby constituting a vacuum insulating material 6. By forming the bubbles of the hard polyurethane foam into a flat shape in this manner, distance of gap between the bubble films becomes shorter and hence thermal conductivity under vacuum of 0.1-0.01Torr can be largely reduced, so that lightweight insulating material of high performance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance heat insulating material used as a heat insulating material for refrigerators and the like, and a refrigerator using the same.

[0002]

2. Description of the Related Art As a heat insulating material for a refrigerator or the like, a heat insulating material having various structures is known, and one of them is a vacuum heat insulating material.
This heat insulating material generally has a structure in which a container made of a metal-plastic laminated film having a gas barrier property is filled with a core material as a reinforcing material in order to maintain a predetermined shape, and the inside is decompressed and sealed. Are known. The heat insulating performance of such a vacuum heat insulating material is largely dependent on the type of the core material, but inorganic fine powder, glass fiber, open-cell foam or the like is used as the core material because of its excellent heat insulating property. Among them, those using an open-cell foam as a core material are lightweight, have good productivity, and are excellent as a heat insulating material for refrigerators, etc. A typical example of this type of vacuum heat insulating material is the invention described in Japanese Patent Publication No. 63-61589, in which a rigid polyurethane foam having open cells is used as a core material to make the cells of the foam fine. Therefore, it has been proposed to obtain a high-performance vacuum heat insulating material.

[0003]

The open cell rigid polyurethane foam used as the core material in the conventional vacuum heat insulating material has a cell diameter of at least 0.1 mm.
The degree is the limit. Basically, when rigid polyurethane foam is used as the core material, the smaller the cells are and the shorter the gap distance between the membranes, the smaller the thermal conductivity becomes when the degree of pressure reduction is constant. Since it is a spherical or oval polyhedron, the bubble diameter ≈ the gap distance between the membranes. Therefore, in the conventional example, the gap distance between the films is about 0.1 mm at the minimum, and the thermal conductivity obtained is 0.1
0.006 to 0.007 kcal at ~ 0.01 Torr
/ M · h · ° C. Furthermore, it is extremely difficult to further reduce the thermal conductivity because a lower pressure is required, which causes a problem in mass production such as a longer exhaust time. Further, since CFC-11 (Chloro FluoroCabon containing chlorine as one of Freon) is used as a foaming agent for the rigid polyurethane foam, there has been a problem that it cannot comply with recent freon regulations.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and by using an open-cell foam as a core material, the thermal conductivity can be further reduced at a pressure reduction degree of 0.1 to 0.01 Torr which enables mass production. It is to provide a lightweight, high-performance, non-CFC insulation material and a refrigerator using this insulation material.

[0005]

Means for Solving the Problems The above-mentioned object is to reduce the thickness of cells of an open-cell foam having flat cells to 0.04 m.
m or less, practically preferably 0.01 to 0.03 mm. Further, it is preferably achieved by a vacuum heat insulating material in which the flat heat insulating material is used as a core material, the core material is covered with a container made of a gas barrier film, and the inside is decompressed and sealed. The open cell foam may have a cell diameter of about 0.1 to 1.0 mm, and is formed into a flat shape having a cell thickness of 0.04 mm or less, preferably 0.01 to 0.03 mm as described above. Is important.

Such flat cells may be formed by any method. For example, before the reaction curing of the open-cell foam is completed immediately after foaming, the cells are compressed by a high pressure press or the like to form flat cells. After curing in a crushed state, cut it to a specified size for use, or after foaming has completely cured the foam, cut it to a specified size and then compress it with a high pressure press etc. The cells may be flattened into a flat shape for molding. In the latter case, the foam is restored to some extent, but this is covered with a container made of a gas barrier film using this as a core material, and the inside is depressurized and sealed, whereby the bubbles are crushed again and become flat.

Further, in order to comply with the CFC regulations, it is preferable that the above-mentioned open-cell foam is a CFC-free foam, and in particular, CO ₂ gas produced by the reaction of water with an isocyanate using water as all the foaming agents. It is preferable to use a water-foamed rigid polyurethane foam foamed by.
In conventional CFC-11 foaming, 1 /
If you compress it to 2 or less and crush it, bubbles will be easily destroyed,
It is difficult to mold air bubbles into a flat shape with a thickness of 0.04 mm or less, but when water is used as all the foaming agents, CF
The heat generation temperature during foaming is higher than that of C-11 foaming (150 →
(185 ° C.), the foam skeleton of the foam immediately after foaming becomes soft, and even if the foam is compressed and crushed, the foam is less likely to be broken, and the foam can be easily formed into a flat shape with a thickness of 0.04 mm or less.

The composition of the water-foamed rigid polyurethane foam may be any composition as long as it has an open cell ratio of about 100%. As the heat insulating material, it is possible to use the open-cell foam having flat-shaped cells alone, but as described above, such an open-cell foam is used as the core material, and this is a container made of a gas barrier film. It is preferable to use a vacuum heat insulating material which is covered and whose interior is decompressed and hermetically sealed, because it has more excellent heat insulating properties. A typical use of such a heat insulating material is as a heat insulating material for refrigerators and the like, but in addition to this, it can be widely applied as a heat insulating material for buildings such as cold storage cars and prefabricated panels.

[0009]

As described above, according to the present invention, the open-cell foam having flat-shaped cells is used as the heat insulating material or the vacuum heat insulating material having the core as the core material. The void distance is several times smaller than the bubble diameter, and the bubble thickness is 0.04 mm or less, preferably 0.01 to 0.03 mm.
By doing so, a high-performance heat insulating material can be obtained. In particular, by covering a container made of a gas barrier film with a heat insulating material having such a bubble thickness as a core material and depressurizing the inside to seal it, a thermal conductivity of 0.005 kcal is obtained at a decompression degree of 0.1 to 0.01 Torr. It is possible to obtain a high-performance vacuum heat insulating material of / m · h · ° C or less.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <Examples 1 and 2> FIG. 1 shows a manufacturing process of an open-celled rigid polyurethane foam which is a core material of this example. The rigid polyurethane foam 4 is an OH obtained by adding ethylene oxide and propylene oxide to tolylenediamine as a polyol component to the raw material.
OH obtained by adding propylene oxide to triethanolamine with a polyol having a valency of 350 mgKOH / g
100 parts by weight of a mixture of a polyol having a valency of 300 mgKOH / g at 6: 4, 4 parts of distilled water as a foaming agent, and a silicone surfactant as a foam stabilizer (trade name "SZ-1923" manufactured by Nippon Unicar Co., Ltd.) 3 parts by weight, 2 parts by weight of a product name "Minico R-9000" manufactured by Activator Chemical Co. as a catalyst, and 2 parts of a product name "Kaorizer No. 1" manufactured by Kao Corporation.
1 part by weight, 1 part by weight of calcium stearate as a communicating agent, and 147 parts by weight of a product name "C-MDI44V20" manufactured by Sumitomo Bayer Urethane Co., Ltd. as an isocyanate component were mixed in a high-pressure foaming machine. ) And as shown in FIG. 1 (2), it is foamed and filled into the space formed by the upper mold 2 and the lower mold 3 made of aluminum whose mold temperature is adjusted to 60 ° C.

Immediately after that, as shown in FIG. 1 (3), the upper mold 2 is gradually pushed in by the high-pressure press 1 so that the hard polyurethane foam 4 has a thickness of about 1/3 and 1/4.
Each was compressed and left to cure for about 10 minutes to obtain a flat-shaped open-cell foam 4a. Further, after demolding, aging was carried out at room temperature, and the product was cut into a predetermined size to obtain a compressed rigid polyurethane foam 4a as a core material shown in FIG. In the thus obtained compressed rigid polyurethane foam 4a, as shown in FIG. 3, flat-shaped cells having a cell thickness A several times smaller than the cell diameter A are formed and compressed to crush the cells. It is easy to obtain a completely open cell foam. Table 1 shows the density, open cell ratio, cell diameter and cell thickness of the obtained compressed rigid polyurethane foam 4a.

Thereafter, the obtained compressed rigid polyurethane foam 4a is heated and dried at 110 ° C. for about 2 hours and covered with a container 5 made of a gas barrier film laminated with a polyethylene terephthalate film, an aluminum foil and a high acrylonitrile film. , The inside is 0.
The pressure was reduced to 1 Torr and sealed to obtain a vacuum heat insulating material 6 shown in FIG. As for the constitution of the container 5, it is not always necessary to laminate both sides of the aluminum foil with a resin film in a sandwich shape as in this example, and one side may be laminated. Further, the metal foil is not limited to the aluminum foil, and other metal foil or metal foil deposited on a resin film instead of the metal foil may be used. Even if the compressed rigid polyurethane foam 4a is used without being covered with the container 5, the compressed rigid polyurethane foam 4a may be directly stored in a wall of a device requiring heat insulating properties, for example, a wall formed by an outer box or an inner box of a refrigerator. good.

<Example 3> Rigid polyurethane foam 4
The same raw material as in Example 1 was used as shown in FIG.
In the same manner as in steps (1) and (2), the mixture was injected into the space formed by the upper mold 2 and the lower mold 3 for foam filling, and allowed to stand for about 10 minutes to cure. Alternatively, it may be free-foamed and cured in a predetermined box. Then, without going through FIG. 1 (3), the mold is removed as shown in FIG. 1 (4), the rigid polyurethane foam 4 is aged at room temperature, and then cut into a predetermined size. )
As shown in (1), it was compressed with a high-pressure press 1 and crushed to a thickness of about 1/3 to obtain a compressed rigid polyurethane foam 4a as a core material shown in FIG.

The compressed rigid polyurethane foam 4a thus obtained had the flattened cells similar to those in Example 1 and was a completely open cell foam. Table 1 shows the density, open cell ratio, cell diameter and cell thickness of the obtained compressed rigid polyurethane foam 4a. In this case, although the crushed rigid polyurethane foam is restored to some extent, the substance values shown in Table 1 are those before restoration.

Thereafter, the compressed rigid polyurethane foam 4a thus obtained was covered with a container 5 made of a gas barrier film in the same manner as in Example 1, and the inside thereof was depressurized to 0.1 Torr and sealed, The vacuum heat insulating material 6 shown in FIG. 4 was obtained. At this time, the compressed rigid polyurethane foam 4a, which is the core material, was crushed again to form flat cells.

The thermal conductivity of the vacuum heat insulating material 6 obtained in Examples 1 and 2 was averaged by using a thermal conductivity measuring device (trade name "HC-071 type") manufactured by Eiko Seiki Co., Ltd. The results measured at a temperature of 24 ° C. are shown in Table 1. As Comparative Examples 1 and 2, before crushing with the high pressure press 1 of Example 2 and about 1
/ 2, crush the rigid polyurethane foam 4
As Comparative Example 3, a vacuum heat insulating material in which a conventional rigid polyurethane foam using freon (CFC-11) as a foaming agent was used as a core material was also measured at the same time and is shown in Table 1.

[0017]

[Table 1]

As is apparent from Table 1, in the compressed rigid polyurethane foams 4a obtained in Examples 1 to 3, the average cell diameter was 0.2 mm and the cell thickness was 0.
It was found that very thin flat bubbles with a thickness of 01 to 0.04 mm were formed, and the void distance between the bubble films was extremely short. Then, by using the open-cell foam formed with the flat-shaped cells, that is, the compressed rigid polyurethane foam 4a as the core material of the vacuum heat insulating material 6, the heat conductivity of the vacuum heat insulating material 6 can be reduced to a degree of decompression of 0 at which mass production is easy. 0.004 kcal / m · h · ° C or less at 1 Torr, which is significantly reduced as compared with Comparative Examples 1 to 3 in which the thickness of the bubble is large and the gap distance between the bubble membranes is long, and extremely excellent heat insulation performance can be obtained. It was Further, since the compressed rigid polyurethane foam 4a is a non-CFC water-foamed rigid polyurethane foam in which water is used as all the foaming agents, there is no problem in terms of CFC regulation.

[0019]

As described above, according to the present invention, the intended purpose can be achieved. That is, the thickness of the bubbles is 0.04 mm or less, preferably 0.01 to 0.03 m.
By constructing an insulating material with an open-cell foam having flattened cells of m, it is possible to realize a lightweight, high-performance and excellent non-CFC insulating material. Further, if this is used as a core material for a vacuum insulating material, Decompression degree of 0.1 to 0.0 for mass production
An excellent vacuum heat insulating material that can significantly reduce the thermal conductivity at 1 Torr can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory view of a manufacturing process of a rigid polyurethane foam according to an embodiment of the present invention.

FIG. 2 is an external perspective view of the same rigid polyurethane foam.

FIG. 3 is an explanatory view of cell shape of the rigid polyurethane foam.

FIG. 4 is a sectional view of the vacuum heat insulating material.

[Explanation of symbols]

1 ... High pressure press, 2 ... Upper mold,
3 ... Lower mold, 4 ... Rigid polyurethane foam, 4a ... Compressed rigid polyurethane foam, 5 ... Container, 6 ... Vacuum heat insulating material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Fukuda 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Living Equipment Division, Hitachi, Ltd.

Claims (7)

[Claims] 1. A heat insulating material comprising an open-cell foam having a flat cell having a cell diameter of 0.1 to 1.0 mm and a cell thickness of 0.04 mm or less. 2. An open cell foam having a flat cell having a cell diameter of 0.1 to 1.0 mm and a cell thickness of 0.04 mm or less is covered with a container made of a gas barrier film, and the inside thereof is covered. A vacuum heat insulating material made by decompressing and sealing. 3. The heat insulating material according to claim 1, wherein the open-cell foam comprises a molded body which is compressed after foaming to crush the cells into a flat shape. 4. The vacuum heat insulating material according to claim 2, wherein the open-cell foam comprises a molded body which is compressed after foaming to crush the cells into a flat shape. 5. The heat insulating material according to claim 1, wherein the open-cell foam comprises a water-foamed rigid polyurethane foam obtained by using water as a foaming agent. 6. The vacuum heat insulating material according to claim 2 or 4, wherein the open-cell foam comprises a water-foamed rigid polyurethane foam obtained by using water as a foaming agent. 7. A refrigerator comprising the heat insulating material or vacuum heat insulating material according to claim 1 as a heat insulating material.