JPH09303947A - Heat insulating box and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict air from entering a heat insulating box and cause a density distribution of a foamed heat insulating material to approach a uniform density by a method wherein an epoxide hardening layer is formed at an interface portion between an inner box of a resin and a compound of a foamed urethane resin. SOLUTION: Resin materials including an isocyanate, a polyol, a foam adjusting agent, a urethane polymer catalyst, a foaming agent, an epoxide compound and a carbon dioxide carbonating catalyst are fed into a space formed by a combination of an inner box 2 of a resin and an outer box 3 of a metal and foamed to make a foamed urethane resin compound 5 having some independent air bubbles including carbon dioxide. At an interface part between the foamed urethane resin compound 5 and the inner box 2 of a resin is formed an epoxide hardened layer 7 together with the intermediate resin layer 6. With such an arrangement as above, it is possible to restrict air from entering the heat insulating box and the cause a density distribution of the foamed heat insulating material to approach a uniform value.

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 used for refrigerators, freezers and the like, and a method for manufacturing the heat insulating box.

[0002]

2. Description of the Related Art In recent years, chlorofluorocarbon (hereinafter referred to as C)
Global environmental problems such as ozone layer depletion and global warming due to CFCs of hydrochlorofluorocarbons (hereinafter abbreviated as HCHC) and fluorocarbons are drawing attention. CFCs and HCFs used as foaming agents in the production of rigid urethane foam used in heat insulation boxes such as refrigerators.
Alternatives are being promoted for the purpose of reducing the amount of C used. As alternative CFCs, volatile foaming agents such as hydrocarbons (hereinafter abbreviated as HC) and hydrofluorocarbons (hereinafter abbreviated as HFC), which have little impact on global environmental problems, and the reaction between isocyanate and water of reactive foaming agents Various investigations have been made on the method of using generated carbon dioxide. However, cyclopentane, which is a typical HC-based foaming agent, is a CFC that has been conventionally used as a general-purpose foaming agent.
Since the gas thermal conductivity is higher than that of No. 11, the foam thermal conductivity of the urethane foam heat insulating material foamed using these HC-based foaming agents is high. In addition, carbon dioxide obtained by the reaction of isocyanate and water in combination with water as a reactive foaming agent has a higher gas thermal conductivity than HC-based foaming agents, so that carbon dioxide inside the closed cells of the foamed heat insulating material is increased. There is a problem that the foam thermal conductivity increases as the carbon ratio increases.

Therefore, conventionally, in order to improve the heat insulating property of the foamed heat insulating material, efforts have been made to reduce the carbon dioxide composition ratio inside the bubbles to reduce the gas thermal conductivity. For example, a method has been proposed in which carbon dioxide inside bubbles is fixed and removed by an epoxide compound to improve the heat insulating property of the foamed heat insulating material (Japanese Patent Laid-Open No. 173311/1995).
No. 4, etc.). When this technique is used, for example, when combined with a volatile foaming agent having a low gas thermal conductivity, carbon dioxide is generated by the reaction of isocyanate with water, and immediately after foaming, the inside of the foam bubbles contains carbon dioxide and the volatile foaming agent. Although it is filled with a mixed gas of steam, the epoxide compound gradually reacts with carbon dioxide to form a carbonate compound and immobilize carbon dioxide. As a result of this reaction, the gas component ratio of the volatile foaming agent having a low gas thermal conductivity increases over time, and as a result, the gas thermal conductivity of the gas mixture in the bubbles is reduced, so that the heat insulating property of the foam is improved. In addition, these foamed heat insulating materials are often filled in a space formed between the resin inner box and the metal outer box to form a heat insulating box.

[0004]

As described above, when the foamed heat insulating material is filled in a closed space of a heat insulating box body in which a resin inner box and a metal outer box are combined and applied to a refrigerator or the like, a refrigerator is used. With long-term use, the heat insulating property of the heat insulating box body may be deteriorated by the effect of air entering the air bubbles through the resin inner box. This is because the intrusion of air into the bubbles changes the gas composition ratio inside the bubbles due to the mixing of air having a high gas thermal conductivity, and the gas thermal conductivity of the mixed gas increases. In particular, when a volatile foaming agent with a low vapor pressure is used, the partial pressure of the volatile foaming agent inside the bubbles will be low, so even if the amount of air that enters the bubbles is the same, heat insulation performance will be improved. Is expected to increase. Therefore, it is necessary to suppress the entry of air into the heat insulating box.

In addition, when the raw material of the foamed heat insulating material is filled in a hermetically sealed container formed between the resin inner box and the metal outer box to perform foam molding, the resin inner box and the metal outer box are used. The foam density of the foamed heat insulating material in the inner portion of the box tends to be higher than the foam density of the foamed heat insulating material in the central portion in the thickness direction of the heat insulating box. Since carbon dioxide is highly permeable, it is distributed in a state that is nearly uniform in the thickness direction of the heat insulating box, but the epoxide compound that fixes carbon dioxide and the carbon dioxide carbonate catalyst are the surface of the heat insulating box. Tends to be distributed in the vicinity of. Therefore, the time-dependent carbon dioxide immobilization reaction does not proceed uniformly and efficiently inside the adiabatic box, and in order to improve this, it is necessary to make the density distribution inside the adiabatic box uniform.

The present invention suppresses the invasion of air into the inside of the heat insulating box and makes the density distribution of the foamed heat insulating material close to uniform, so that the heat insulating property is excellent and the deterioration of the heat insulating property over time is small. It is intended to provide a heat insulating box.
Moreover, this invention aims at providing the manufacturing method of such a heat insulation box.

[0007]

A heat insulating box body of the present invention comprises a urea bond, a carbon dioxide carbonation catalyst, and an epoxide compound in a space portion formed by combining a resin inner box and a metal outer box. And a carbon dioxide compound, which is a reaction product of carbon dioxide, which is a heat-insulated box filled with a closed-cell urethane foam resin composition, wherein an epoxide is provided at a boundary portion between the resin inner box and the urethane foam resin composition. It is characterized in that a hardened layer is formed. Further, since the intermediate resin layer containing the epoxide curing active group is arranged on the inner surface of the resin inner box, a more excellent effect is exhibited.

The method for producing a heat-insulating box of the present invention comprises an isocyanate, a polyol, and a space formed between a metal outer box and a resin inner box having a resin layer containing an epoxide curing active group on its inner surface. Foam stabilizer, urethane polymerization catalyst, foaming agent,
It is characterized by including a step of forming a urethane foam resin composition having closed cells containing at least carbon dioxide by injecting and foaming a resin composition raw material containing an epoxide compound and a carbon dioxide carbonation catalyst. Further, it is preferable that the metal outer box has a resin layer containing an epoxide curing active group on the inner surface. Particularly, when the resin layer containing the epoxide-curing active group is hydrated, more excellent effect is exhibited.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The basic principle by which the present invention is applied to form a heat insulating box having excellent heat insulating properties is as follows. That is, a resin containing an isocyanate, a polyol, a foam stabilizer, a urethane polymerization catalyst, a foaming agent, an epoxide compound, and a carbon dioxide carbonation catalyst in a space portion formed by combining a resin inner box and a metal outer box. The raw material is injected and foamed to form a urethane foam resin composition having closed cells containing at least carbon dioxide. In the most preferred form containing the reactive foaming agent water as the foaming agent, the foamed urethane resin composition comprises
A urethane-bonded resin foam is formed by the reaction of the isocyanate and the polyol represented by the following formula (1), and a urea bond is formed by the reaction of the isocyanate and the water represented by the formula (2), and at the same time carbon dioxide is generated. This carbon dioxide is fixed by the carbonate formation reaction with the epoxide compound as shown in formula (3) because the carbon dioxide carbonation catalyst is present inside the bubbles of the urethane resin foam, and the carbon dioxide inside the bubbles is fixed. The composition ratio gradually decreases and the heat insulating performance improves with time. At this time, the air bubbles in the urethane foam resin composition in the heat insulating box are gradually reduced in pressure, so that air is likely to enter from the outside of the box through the resin inner box material. The present invention solves this.

[0010]

Embedded image

In the formula, R, R ', R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or substituents. Further, in the formula (3), the epoxide compound is represented by a monofunctional, three-membered ring ether, but the reaction proceeds similarly even if it has four or more membered rings.

In the present invention, as described above, in the space between the resin inner box and the metal outer box, the carbonate compound produced by the reaction of the epoxide compound and carbon dioxide, the carbon dioxide carbonate formation catalyst, and It is characterized in that it is filled with a urethane foam resin composition containing urea bonds and composed of closed cells, and has an epoxide cured layer at the boundary between the resin inner box and the urethane foam resin composition. Therefore, the amount of air intruding from the outside of the heat-insulating box is reduced by the configuration of the resin inner box / epoxide cured layer / urethane foam resin composition as compared with the conventional resin inner box / urethane foam resin configuration. be able to.

The epoxide cured layer may be formed at the time of assembling and manufacturing, but it is preferably formed in the heat insulating box after manufacturing the heat insulating box. That is, when the epoxide curing active group is present on the inner surface of the resin inner box,
The epoxide compound existing in the vicinity of the inner surface of the resin inner box reacts with the epoxide curing active group to form a cured layer.
Air bubbles of the urethane foam resin composition are easily diffused and permeated by air because the resin wall is thin. However, if this epoxide cured layer is formed at the boundary portion where the resin inner box and the bubble portion are in contact, Since it also serves to thicken the resin wall of the bubbles, it has an effect of suppressing the invasion of air into the bubbles.

As the epoxide curing active substance, a general curing agent for epoxy resin can be used. For example, a basic, acidic, or neutral polyaddition type curing agent reacts with an epoxide compound to form a cured layer. Further, the catalyst type curing agent forms a cured layer by addition polymerization of an epoxide compound. Further, a substance having an epoxide curing active group having a similar skeleton can be used. Also, these substances having epoxide curing activity can be used in combination. When a substance having an epoxide curing active group is provided on the inner surface of the resin inner box, a method of adding the epoxide curing active substance to the resin inner container, a method of applying the epoxide curing active substance to the inner surface of the inner container, etc. However, by arranging the intermediate resin layer containing the epoxide curing active group on the inner surface of the resin inner box, a more excellent effect is exhibited. That is, the gas permeation suppressing effect of the resin layer itself containing the epoxide curing active group can also be used.

Further, in the constitution of the present invention, the foam density of the urethane foam resin composition in the heat insulating box is made as uniform as possible in the box thickness direction, and the epoxide compound and the carbon dioxide carbonation catalyst are distributed in the thickness direction. Can be brought close to uniform, and there is also an effect that the carbonation reaction of the epoxide compound with the carbon dioxide generated at the time of foaming can be efficiently performed. That is, at the time of foaming, on the surface of the resin layer containing the epoxide curing active group disposed on the inner surface of the inner box,
Since the urethane reaction is activated and bubbles are easily formed by the reaction heat, the foam density on the inner surface of the box is reduced and the difference from the foam density on the center of the box is reduced. When the epoxide curing active group is a polyaddition type curing agent system, it itself reacts with the isocyanate of the urethane raw material, so that it reacts on the surface of the resin layer to generate heat and promote foaming. Further, when the epoxide curing active group is a catalyst type curing agent system, since it also has an activity as a catalyst for the urethane reaction, the urethane reaction on the surface of the resin layer is activated to generate heat and promote foaming. . The epoxide compound is cured on the surface and inside of the resin layer having an epoxide curing active group.

Further, in the constitution of the present invention, a more excellent effect is exhibited by previously preparing the resin layer containing the epoxide-curing active group and hydrating it or absorbing it. That is, in addition to the high urethane reaction activity on the surface of the resin layer, the presence of water causes the reaction with isocyanate in the urethane raw material to generate carbon dioxide. At this time, workability is good because the excess water does not exist as free water when hydrated, rather than moisture absorption, and deterioration of the urethane resin in the urethane foam resin composition over time does not easily occur. . In the present invention, as the substance having an epoxy curing active group, a tertiary amine is particularly preferable. Since it does not itself react with the urethane raw material, the active groups remain on the outermost surface of the inner box made of resin, and the epoxy compound is in a state where it easily undergoes a curing reaction to form a poly (epoxide) having an ether bond. . In addition, tertiary amines can also form hydrates to further enhance the reactivity of the surface layer. Further, in order to exert more effects in the present invention having such a configuration, not only the resin layer containing an epoxide curing active group is disposed on the inner surface of the resin inner box, but also the resin layer containing an epoxide curing active group. It is also preferable to dispose on the inner surface of the metal outer box. In the heat insulating box of the present invention, and the manufacturing method thereof, the resin layer having an epoxide curing active group does not need to be placed on the entire inner surface of the heat insulating box, and the inner box and the outer box each have an internal area of The effect can be obtained if the average coverage is 50% or more. That is, even if air enters from the part of the heat insulating box where the resin layer having the epoxide curing active group is not arranged, it does not easily diffuse in the plane direction of the inner box inside the heat insulating box, so the total heat insulating performance is improved. Can be expected to be suppressed.

Specific embodiments of the present invention will be described below. << Embodiment 1 >> FIG. 1 is a longitudinal sectional view of a heat insulating box 1 according to the present invention, and FIG. 2 is an enlarged view schematically showing a cross section of the heat insulating box 1. Inner box surface material 2 which is a vacuum molded body of ABS resin composition
The face material 6 of the intermediate resin layer having the epoxide curing active substance is arranged on the inner surface side of the box. A foamed heat insulating material 5 is filled in a space formed by a flange 4 between the inner box and the outer box surface member 3 formed by forming a steel plate. An epoxide cured layer 7 is formed at the boundary portion between the face material 6 of the intermediate resin layer having an epoxide curing active substance and the foamed heat insulating material 5. This foamed heat insulating material 5 contains a urethane bond in which a isocyanate reacts with a polyol, a urea bond in which a water reacts with an isocyanate, a carbon dioxide carbonation catalyst, and a carbonate compound in which a carbon dioxide and an epoxide compound are additionally reacted in the resin part. The vapor of the volatile foaming agent is trapped inside the bubbles.

<Embodiment 2> The method for manufacturing the heat-insulating box 1 of FIG. 1 is such that an inner surface of the inner box surface member 2 which is a vacuum molded body of an ABS resin composition has an epoxide curing active substance on the inner surface of the box. Urethane raw material components and the like are mixed and agitated into a box space in which an inner box formed by arranging a face material 6 of a resin layer and an outer box face material 3 formed by processing a steel plate are formed through a flange 4. Then, foaming is performed inside the box space portion. As a raw material, a polyol composition, a foam stabilizer, a urethane polymerization catalyst, and a volatile foaming agent and a reactive foaming agent as a foaming agent are mixed in advance to obtain a premix component A. Further, an epoxide mixed solution component B is prepared by mixing and stirring an epoxide compound and a carbon dioxide carbonation catalyst. After that, the three components of the premix component A, the epoxide mixed solution component B, and the component C consisting of isocyanate are mixed and stirred using a high-pressure foaming machine, and the mixture is poured into the box space.

Next, the constituent materials of the present invention will be described in detail. As the substance having an epoxide curing active group,
As described above, a general epoxy resin curing agent can be used. As polyaddition type curing agents, basic aliphatic polyamines, aromatic polyamines, polyamides, acidic acid anhydrides, phenols, neutral polymercaptans, etc. are known and these react with epoxide compounds. To form a hardened layer. For example, diethylenetriamine, triethylenetetramine, 3,9- (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane, metaxylenediamine, diaminodiphenylmethane, dimer acid polyamide, phthalic anhydride, Tetrahydromethyl phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, methyl nadic acid anhydride, phenol novolac, polymercaptan, polysulfide and the like. Also,
As the catalyst type curing agent, a tertiary amine, a Lewis acid complex and the like are known, and a cured layer is formed by addition polymerization of an epoxide compound. For example, tris (dimethylaminomethyl) phenol, 2-ethyl-4-methylimidazole, boron trifluoride ethylamine complex and the like. Curing agents for epoxy resins other than those described here may be used alone or in combination.

Intermediate resin layer 6 containing epoxide curing active groups
As the above, it can be constituted by dispersing, coating or dissolving the epoxy resin curing agent in a general-purpose resin composition and mixing them. Furthermore, a composition in which an epoxide curing active group is introduced into the resin skeleton may be used. The general-purpose resin composition may be one that is used on a daily basis, for example, polyolefin, polystyrene, polyvinyl alcohol, butyral resin, polyvinyl chloride, vinyl chloride vinyl acetate copolymer resin, polyethylene terephthalate, ethylene vinyl alcohol copolymer resin. , Ethylene vinyl acetate copolymer resin, vinylidene chloride resin, acrylonitrile resin,
Examples include polyamides such as nylon, gelatin, and fluorine-containing resins such as polyvinyl fluoride. In particular, when a polyvinyl alcohol, an ethylene vinyl alcohol copolymer resin, a vinylidene chloride resin, or an acrylonitrile resin having a high gas barrier property is used, the effect is high. Further, an epoxide-curing active group may be introduced into the resin composition itself. For example, phenolic resin, styrene-maleic anhydride copolymer resin, polyallylamine, boron trifluoride complex of polyallylamine, adduct of trimellitic anhydride to vinyl alcohol resin or polyamide, and tertiary amine group as main chain And resins having side chains. As a method of arranging the intermediate resin layer 6 having an epoxide curing active group on the inner surface of the resin inner box 2, a general method such as solution coating, spray coating, laminating in a sheet structure, sticking or adhesion can be applied.

As the epoxide compound used in the present invention, any compound having an epoxy group or a glycidyl group can be applied. The epoxide compound may be monofunctional or polyfunctional. Further, a compound having an unsaturated group in the molecule or an oligomer having an epoxy group at both ends,
It is also possible to use oxetane, which is a 4-membered ring ether, or a derivative thereof. In addition, epoxide compounds are gases, liquids,
Any form of solid may be used. Specific examples include ethylene oxide, propylene oxide, 1,2-butylene oxide, cis 2,3-butylene oxide, trans 2,
3-butylene oxide, isobutylene oxide, 1,2
-Epoxy hexane, glycidyl methyl ether, glycidyl ethyl ether, glycidyl butyl ether, glycidyl phenyl ether, methacrylic acid glycidyl ester, neopentyl diglycidyl ether and the like.

As the carbon dioxide carbonation catalyst of the present invention, compounds having a nucleophilic property or an electrophilic property can be applied alone or in combination. As the nucleophile, a halogen ion is effective, and it is particularly preferable that the halogen ion is a counter ion of an onium salt or an alkali halide. As the electrophile, Lewis acidic metal halide, organic tin halide, organic tin fatty acid ester and the like are preferably used. As a specific example, the nucleophile is particularly preferably a halogenated tetraalkylammonium salt or a halogenated tetraalkylphosphonium salt, and the alkyl group is not particularly limited. Also,
As the alkali halide, fluorides such as lithium, sodium, potassium and cesium, chlorides, bromides, iodides and the like can be applied. As the electrophile, zinc halide is particularly preferable, and zinc chloride, zinc bromide, zinc iodide and the like are preferable. Furthermore, dibutyltin dilaurate is particularly preferable. By using the above catalyst, carbon dioxide and an epoxide compound cause an addition reaction with time in a urethane foam to synthesize a liquid or solid cyclic carbonate composition. In particular, in the presence of an onium salt compound, the reaction easily proceeds at room temperature and atmospheric pressure, which is preferable.

In the present invention, the foaming agent may be a reactive foaming agent alone or a combination of a volatile foaming agent and a reactive foaming agent. The reactive foaming agent of the present invention is preferably a compound which reacts with water or an isocyanate such as a lower carboxylic acid to generate carbon dioxide.
When a volatile foaming agent is used in the present invention, the volatile foaming agent acts as a main foaming agent of the resin composition, is a compound having good compatibility with the polyol composition, and has a gas thermal conductivity. A compound having a small value is desirable. As specific examples, hydrocarbon compounds such as cyclopentane, normal pentane, isopentane, neopentane, butane, and isobutane are suitable from the viewpoint of global environment protection.
In particular, it is desirable to apply cyclopentane, which has a low gas thermal conductivity. Further, for the same reason, HFC-356 mmf, which is a hydrofluorocarbon type foaming agent, HFC-
245fa or the like can be applied. Further, there is no problem even if two or more volatile foaming agents are mixed and applied.

The isocyanate, the polyol, the foam stabilizer, the urethane polymerization catalyst, etc., which compose the urethane foam resin composition 5 of the present invention, are general-purpose raw materials applied to general hard or soft urethane foam heat insulating materials. It can be used without any problems. In addition, more preferably, isocyanate is a crude MDI and polyol is a hydroxyl value of 400-5.
Good application of 50 mg KOH / g tolylenediamine polyether polyol. Further, as the foam stabilizer, a silicone-based foam stabilizer is suitable. The resin inner box 2 of the present invention
As for the material of, a synthetic resin used for a heat insulating box such as a refrigerator can be applied. For example, acrylonitrile butadiene styrene (ABS) resin, high impact polystyrene (HIPS) and the like.

[0025]

EXAMPLES Next, specific examples of the present invention will be described. << Example 1 >> As a polyol, a hydroxyl value of 465 mg KO
100 parts by weight of H / g tolylenediamine-based polyether polyol (GR46 of Takeda Pharmaceutical Co., Ltd.), a silicone surfactant (Nippon Unicar Co., Ltd.) as a foam stabilizer.
3 parts by weight of TY19), 1.3 parts by weight of urethane polymerization catalyst (Kaolizer KL1 manufactured by Kao Corporation), 1 part by weight of pure water as a reactive foaming agent, and 10 parts by weight of cyclopentane as a volatile foaming agent. Each was prepared and these were mixed to prepare a premix component A. The epoxide compound was 8 parts by weight of 1,2-epoxybutane, and the carbon dioxide carbonation catalyst was a mixture of 5 parts by weight of tetrabutylammonium bromide and 1 part by weight of zinc chloride.
Component B was prepared by mixing these. As the isocyanate, 140 parts by weight of crude MDI having an amine equivalent of 135 was used as the component C. The isocyanate equivalent ratio was 1.1 with respect to the premix component A, and the composition was adjusted so that the urethane reactivity was a gel time of 50 seconds. Also,
The curing conditions during foam molding were a jig temperature of 45 ° C. and 8 minutes.

ABS resin face material was used as the resin inner box, and tris (dimethylaminomethyl) phenol was added to the ethylene vinyl acetate copolymer resin at 5% by weight on the inner surface side.
The mixed resin sheets were stuck together. This resin inner box was combined with a metal outer box made of an iron surface material to form a box body. Into the space formed between the inner box and the outer box of the box body, the three components of the premix component A, the component B, and the component C are mixed and stirred by a high-pressure foaming machine and injected, Foamed. In this way, the space portion was filled with the urethane foam resin composition to produce a heat insulating box.

Example 2 An ABS resin face material was used as the resin inner box, and a resin sheet obtained by adding 3% by weight of trimellitic anhydride to an ethylene vinyl alcohol copolymer resin was provided on the inner surface of the inner sheet. About 80% of the total internal area was bonded, except for the inner corners. A heat insulating box was produced in the same manner as in Example 1 except that the resin inner box and the metal outer box made of an iron surface material were combined to form a box.

Example 3 A surface material made of ABS resin was used as a resin inner box, and a methyl alcohol solution of a resin obtained by chlorinating a boron trifluoride complex with an amine portion of about 30% of polyallylamine was used on the inner surface side. A resin layer was formed by coating and drying. An iron surface material was used as the metal outer box, and the same resin layer as the inner box was formed on the inner surface side. These resin layers were further hydrated by moisture absorption for about 0.5% by weight,
A box body was constructed by combining these resin inner boxes and metal outer boxes. Except for this, the heat insulating box was manufactured in the same manner as in Example 1.

Comparative Example 1 An adiabatic box was manufactured in the same manner as in Example 1 except that the box body was formed by combining the ABS resin inner box and the iron outer surface metal outer box.

Comparative Example 2 A face material made of ABS resin was used as a resin inner box, and an ethylene vinyl acetate copolymer resin sheet was attached to the inner surface of the face material. With this resin inner box,
A heat-insulating box body was produced in the same manner as in Example 1 except that a metal outer box made of an iron surface material was combined to form a box body.

The heat-insulating box bodies of Examples 1 to 3 and the heat-insulating box bodies of Comparative Examples 1 and 2 produced by the above method were left at room temperature of 25 ° C. for 1 week, and then the heat-insulating box bodies were disassembled. The foam thermal conductivity was evaluated. Furthermore, the nuclear insulation box produced simultaneously under the same conditions was left at room temperature for 3 months, and then the insulation box was disassembled to evaluate the foam thermal conductivity, foam density and the like. For the analysis of foam thermal conductivity, a 200 x 200 x 25 mm size foam sample was cut out from the center of the urethane foam resin part that was taken out by disassembling the heat-insulating box, and made into an AUTO-Λ made by Eiko Instruments Co., Ltd. The foam thermal conductivity at an average temperature of 24 ° C. was measured. The amount of air inside the heat insulating box was obtained by finely pulverizing the same sample in a vacuum and collecting and measuring the amount of air that diffused. Further, the foam density is an average density of 10 mm in the thickness direction (inner box side) from the inner box side of the urethane foam resin taken out of the heat insulation box body, and an average density of 10 mm in the thickness direction central portion (center portion). The average density (outer box side) for 10 mm in the thickness direction was measured from the outer box side. Further, the epoxide cured product formed on the surface and inside of the intermediate resin layer arranged on the inner surface of the resin inner box or the intermediate resin layer arranged on the inner surface of the metal outer box was analyzed and evaluated.

Table 1 shows the evaluation results of Examples 1 to 3, Comparative Example 1 and Comparative Example 2. Comparative Example 1 uses a conventional heat insulating box structure, and Comparative Example 2 shows a structure obtained by removing the epoxy curing active substance from the intermediate resin layer arranged on the inner surface of the resin inner box from the heat insulating box structure of Example 1. is there. As can be seen from Table 1, in the foamed urethane resin composition in the heat insulating box, the difference in the density between the center part in the thickness direction of the box and the vicinity of the face material is smaller in the example according to the example than in the comparative example. Therefore, the decrease in the thermal conductivity in the first week is accelerated. Further, since the cured product of the epoxide compound is generated in the intermediate resin layer, the invasion of air can be suppressed, and thereby the ultimate thermal conductivity after 3 months is reduced. Further, the effect on averaging the foam density is enhanced by hydrating the resin layer containing epoxide-curing active groups.

[0033]

[Table 1]

[0034]

As described above, according to the present invention, by having an epoxide curing layer at the boundary between the resin inner box and the urethane foam resin composition, the invasion of air into the inside of the heat insulating box is suppressed. be able to. In addition, by forming a resin layer containing epoxy curing active groups in advance on the inner surface of the resin inner box and foaming the urethane resin, the density distribution inside the heat insulating box can be made close to uniform, improving the thermal conductivity. Can be uniformly and efficiently advanced. Therefore, it is possible to provide a heat-insulating box having excellent heat-insulating properties and having little deterioration in heat-insulating properties over time.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view schematically showing a main part of the heat insulating box.

[Explanation of symbols]

 1 Thermal Insulation Box 2 Resin Inner Box 3 Metal Outer Box 4 Flange 5 Urethane Foam Resin Composition 6 Intermediate Resin Layer 7 Epoxide Cured Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Sonoda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A space formed by combining an inner resin box and an outer metal box contains a urea bond, a carbon dioxide carbonate catalyst, and a carbonate product of a reaction product of an epoxide compound and carbon dioxide. A heat-insulating box body filled with a urethane foam resin composition composed of closed cells, wherein an epoxide cured layer is formed at a boundary portion between the resin inner box and the urethane foam resin composition. Insulation box body to do. 2. The heat-insulating box body according to claim 1, further comprising an intermediate resin layer containing an epoxide curing active group on the inner surface of the resin inner box. 3. An isocyanate, a polyol, a foam stabilizer, a urethane polymerization catalyst, and foaming in a space formed between a metal outer box and a resin inner box having a resin layer containing an epoxide curing active group on its inner surface. Injecting a resin composition raw material containing an agent, an epoxide compound, and a carbon dioxide carbonation catalyst, and foaming the resin composition raw material to form a urethane foam resin composition having closed cells containing at least carbon dioxide. Method of manufacturing heat insulating box. 4. The method for manufacturing a heat insulating box according to claim 3, wherein the metal outer box has a resin layer containing an epoxide curing active group on the inner surface. 5. The method for manufacturing a heat insulating box according to claim 3, wherein the resin layer containing an epoxide curing active group is hydrated.