JPH07293785A - Manufacture of heat insulating element and heat insulating wall - Google Patents

Abstract

PURPOSE:To improve durability and heat insulating performance by mixing a hard urethane foam raw material of continuous foaming type with a thermal decomposition gas generating substance such as azodicarbon amid, and injection- foaming them for generation of a hard urethane foam block of continuous foam structure. CONSTITUTION:A hard urethane foam raw material with which a powder azoji carbon amid is mixed is injection-foamed to obtain a hard urethane foam block 4 of continuous foam structure. When the temperature of a foam center part has lowered sufficiently after the completion of hardening, the surface material 5 of kraft paper is removed, and the hard urethane foam block 4 is cut to a prescribed size to obtain a hard urethane foam panel 8. The hard urethane foam panel 8 is then decompressed to the thermal decomposition temperature of the azoji carbon amid to be dried. It is sheathed with metal-laminate film 3 together with an absorbing agent, and its inside is decomposed and sealed to obtain a heat insulating element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulator used for refrigerators, frozen prefabs and the like.

[0002]

2. Description of the Related Art Recently, in order to improve the heat insulating performance of a heat insulating box, attention has been paid to the use of a heat insulating body whose inside pressure is reduced. As the core material of this heat insulating body, for example, JP-A-61-15
As disclosed in Japanese Patent No. 3480, it has been proposed to use a rigid urethane foam having open cells as a core material.

This Japanese Patent Laid-Open No. 61-153480 will be described with reference to FIG. 4. In the figure, reference numeral 1 is a heat insulator, and a hard urethane foam 2 having open cells is covered with a metal-laminate film 3, and the inside pressure is reduced. And it is sealed. The rigid urethane foam 2 is produced by foaming using an organic polyisocyanate, a polyol, a catalyst, a foam stabilizer, a foaming agent and a cell communicating agent.

[0004]

However, in the production of the heat insulating body 1 as described above, the strength of the rigid urethane foam 2 is important in terms of quality, particularly from the viewpoint of preventing the deformation of the heat insulating body 1 after the vacuum sealing. In the manufacturing process of the rigid urethane foam 2, a block of rigid urethane foam is foamed by using a face material made of kraft paper as a face material and cut into a predetermined size to obtain the rigid urethane foam 2. In the process, the central part heats up due to the reaction heat, and oxygen in the air permeates into the central part through the surface material of kraft paper and the bubbles of the open-cell structure, so that the oxidation reaction occurs particularly strongly in the central part.

As a result, the foam in the central part undergoes a decomposition reaction at the molecular level and its strength is lower than that of the other parts. Therefore, it is not suitable as a core material because it is partially deformed and collapsed by atmospheric compression after vacuum sealing. It could be a good material. Therefore, securing stable strength has been a major problem in manufacturing.

In view of the above-mentioned problems, the present invention stably produces a rigid urethane foam having a strength to withstand atmospheric compression in the process of producing a rigid urethane foam as a core material of a heat insulating body, thereby achieving excellent durability. Another object of the present invention is to provide a heat insulating body having heat insulating performance and a heat insulating wall using the heat insulating body.

[0007]

In order to solve the above-mentioned problems, the present invention is obtained by mixing an open-cell type rigid urethane foam raw material with a thermally decomposable gas generating substance such as azodicarbonamide and injecting and foaming. A hard urethane foam block having an open-cell structure is cut into a predetermined size, and this is used as a core material, which is covered with a metal-plastic slaminate film, and the inside is vacuum-sealed to obtain a heat insulator.

Further, in the production of the heat insulating body, the heat treatment is carried out at a temperature not lower than the thermal decomposition temperature before sealing under reduced pressure.

Further, the obtained heat insulating body is integrally foamed with a hard urethane foam heat insulating material to form a heat insulating wall.

[0010]

[Function] Of the above-mentioned constitution, a rigid urethane foam block having an open-cell structure obtained by mixing a foamable raw material of a continuous-cell type urethane with a thermally decomposable gas generating substance such as azodicarbonamide and injecting and foaming the block When the temperature of the central part rises, a thermally decomposable gas generating substance such as azodicarbonamide causes thermal decomposition to generate an inert nitrogen gas. As a result, until a sufficient time elapses and the temperature is cooled to room temperature, a higher temperature portion becomes a nitrogen gas atmosphere, and oxygen in the air is less likely to permeate and enter the high temperature portion.

Therefore, even if the temperature at the center of the block rises, the oxidation reaction does not occur, the phenomenon of lowering the foam strength does not occur, and stable foam quality can be secured.

By using the hard urethane foam obtained by the above-mentioned constitution as the core material, it is possible to obtain a heat insulator having an excellent durability and strength against atmospheric compression.

Further, since the heat treatment is carried out at a temperature higher than the pyrolysis temperature before the pressure-reduced airtightness is closed, all the pyrolyzable gas generating substances such as undecomposed residual azodicarbonamide are decomposed, resulting in a heat insulator. As a result, there is no possibility that an extremely small amount of inert gas will be generated over time, and a heat insulator having excellent heat insulating performance can be obtained.

Further, since undecomposed residual thermally decomposable gas generating substances such as azodicarbonamide do not remain, even when integrally foamed with the rigid urethane foam heat insulating material, the reaction heat causes gas generation in the heat insulating body. In addition, since it has durability and strength, it is possible to provide a heat insulating wall which is capable of ensuring heat insulating performance over time and having no deformation.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings of FIGS. 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.

Reference numeral 4 is a rigid urethane foam block having an open cell structure obtained by injecting and foaming a rigid urethane foam raw material of an open cell type in which powdery azodicarbonamide is mixed.

After the curing, the temperature at the center of the foam is sufficiently lowered, and the hard urethane foam block 4 is cut to a predetermined size except for the face material 5 of kraft paper.
A rigid urethane foam panel 8 is obtained.

Thereafter, the rigid urethane foam panel 8 is dried under reduced pressure to 200 ° C., which is the thermal decomposition temperature of azodicarbonamide, and covered with a metal-laminate film 3 together with an adsorbent (not shown), and the inside is depressurized. And then seal and insulate 9
To get

After that, if necessary, the heat insulating body 9 was adhered to the face material 10 of the iron plate and further integrally foamed with the hard urethane foam heat insulating material 11 to obtain the heat insulating wall 12.

A rigid urethane foam block having an open-cell structure obtained by injecting and foaming an open-cell type rigid urethane foam raw material in which azodicarbonamide is mixed as described above is used. Dicarbonamide undergoes thermal decomposition to generate inert nitrogen gas. As a result, until a sufficient time elapses and the temperature is cooled to room temperature, a higher temperature portion becomes a nitrogen gas atmosphere, and oxygen in the air is less likely to permeate and enter the high temperature portion.

Therefore, even if the temperature of the central portion of the block rises, the oxidation reaction does not occur, the phenomenon of lowering the foam strength does not occur, and stable foam quality can be secured. And
By using the rigid urethane foam obtained by the above-mentioned structure as the core material, the heat insulator 9 having excellent durability strength that can withstand atmospheric compression can be obtained.

Further, since the rigid urethane foam panel 8 is dried under reduced pressure at a temperature higher than the thermal decomposition temperature before sealing under reduced pressure, all undecomposed residual azodicarbon amide is decomposed, and as a result, it is aged as a heat insulator and is aged over time. There is no possibility that a very small amount of inert gas will be generated, and the heat insulator 9 having excellent heat insulating performance can be obtained.

Further, even if the heat insulating body 9 is integrally foamed with the rigid urethane foam heat insulating material 11, no gas is generated in the heat insulating body 9 due to reaction heat, and the heat insulating performance is secured over time.
Moreover, since it is not subjected to an oxidation reaction, it is possible to provide a heat insulating wall which has durability strength and is not deformed.

[0024]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, a rigid open-cell type urethane foam raw material is obtained by mixing a pyrolytic gas generating substance such as azodicarbonamide with a raw urethane foam material and injecting and foaming the mixture. A urethane foam block is cut into a predetermined size, and this is used as a core material and is covered with a metal-plastic slaminate film, and the inside is vacuum-sealed to obtain a heat insulator. When the temperature at the center of the block rises. , A thermally decomposable gas generating substance such as azodicarbonamide causes thermal decomposition to generate inert nitrogen gas.
As a result, until a sufficient time elapses and the temperature is cooled to room temperature, a higher temperature portion becomes a nitrogen gas atmosphere, and oxygen in the air is less likely to permeate and enter the high temperature portion.

Therefore, even if the temperature of the central portion of the block rises, the oxidation reaction does not occur, the phenomenon of lowering the foam strength does not occur, and stable foam quality can be secured. Then, by using the rigid urethane foam obtained by the above-mentioned constitution as the core material, it is possible to obtain a heat insulator having excellent durability and strength that can withstand atmospheric compression.

Further, since the heat treatment is carried out at a temperature higher than the thermal decomposition temperature before sealing under reduced pressure, all the thermally decomposable gas generating substances such as undecomposed residual azodicarbonamide are decomposed, resulting in a heat insulator. As a result, there is no possibility that an extremely small amount of inert gas will be generated over time, and a heat insulator having excellent heat insulating performance can be obtained.

Further, since undecomposed residual azodicarbonamide and other thermally decomposable gas-forming substances do not remain, even if the rigid urethane foam heat insulating material is integrally foamed, gas is generated in the heat insulator due to reaction heat. In addition, since it has durability and strength, it is possible to provide a heat insulating wall which is capable of ensuring heat insulating performance over time and having no deformation.

[Brief description of drawings]

FIG. 1 is a perspective view of a rigid urethane foam block according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a heat insulator in one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a heat insulating wall according to an embodiment of the present invention.

FIG. 4 is a sectional view of a conventional heat insulator.

[Explanation of symbols]

 3 Metal-Plastic Laminated Film 4 Hard Urethane Foam Block 9 Heat Insulator 11 Hard Urethane Foam Insulation 12 Heat Insulation Wall

Claims (3)

[Claims] 1. A rigid urethane foam block having an open cell structure obtained by mixing a raw material of a rigid urethane foam composed of open cells with a thermally decomposable gas generating substance such as azodicarbonamide and injecting and foaming the block. A method for producing a heat insulator obtained by cutting into pieces, covering with a metal-plastic slaminate film using this as a core material, and hermetically sealing the inside under reduced pressure. 2. The method for producing a heat insulator according to claim 1, wherein the heat treatment is carried out at a temperature equal to or higher than the thermal decomposition temperature of the thermally decomposable gas generating substance such as azodicarbonamide before being sealed under reduced pressure. 3. A hard urethane foam block having an open-cell structure formed by mixing a thermally decomposable gas generating substance such as azodicarbonamide as a core material, and before covering the core material with a metal-plastic laminate film. An adiabatic wall formed by covering a heat-insulating body, which has been heated at a temperature equal to or higher than the thermal decomposition temperature of the thermally decomposable gas-generating substance and then hermetically sealed under reduced pressure, with a rigid urethane foam composed of closed cells.