JPH05200760A - Insulation material manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] In a method of manufacturing a heat insulating material used for keeping heat and cold in a refrigerator or the like, a skin layer without bubbles is generated and the material is wasted, or the heat insulating effect is affected. Solves the problem that the shape of bubbles that give
Manufacture heat-insulating materials with excellent heat-insulating effects and effectively use the materials. A container 6 having an opening 7 and an air permeable bottom 8 at the other end facing the opening 7 and an air permeable wall 9 around the same is filled with a foaming resin 10, and at the same time when a curing reaction starts, the container is filled. 6
The communication air bubbles 11 are formed inside the foamable resin 10 by controlling the pressures of the openings 7 and the air permeable bottom portion 8 and the pressure around the air permeable wall body 9, respectively. [Effect] A communicating air bubble having a long axis and a short axis of a required shape can be formed, and a heat insulating material excellent in heat retention and cold insulation can be manufactured without waste.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat insulating material having a high heat insulating effect, which is used for a heat insulating box body such as a refrigerator, a freezer, a refrigerator, a freezer prefab, and a portable refrigerator.

[0002]

2. Description of the Related Art In a refrigerator, a freezer, a refrigerator, a freezer prefab, a portable refrigerator, etc., a heat insulating material used for a heat insulating box is an important constituent material for supporting its performance. In particular, in recent years, there has been an increasing demand for large-capacity refrigerators for household refrigerators and the like as their storage capacity increases.

On the other hand, the scale of the house is not yet sufficient as compared with the countries in Europe and America, and therefore, in order to effectively utilize the extremely limited floor area, a large-capacity refrigerator having a high internal volume efficiency is required. In order to meet these requirements, conventionally, as a heat insulating material for keeping heat and cold in a refrigerator or the like, for example, JP-A-58-50392 and JP-A-58-5 have been used.
As disclosed in Japanese Patent No. 0394, a heat insulating material in which an inorganic powder (heat insulating material) such as expanded pearlite is filled in a bag made of a plastic laminated film, deaerated in a vacuum, and sealed is used.

Further, in order to enhance the heat retaining and cooling effect of the heat insulator, the heat insulating material has a constitution in which an inorganic heat insulating material such as hollow spherical shell powder such as diatomaceous earth and glass fiber is combined with an organic heat insulating material such as hard polyurethane foam. Body is JP-A-58-10637
No. 4, JP-A-59-142135 and the like, and more particularly, a resin foam having an open-cell structure, as recently found in JP-A-63-189771, JP-A-02-72295 and the like, is disclosed. There is disclosed an example in which a heat insulating material having a high heat insulating property is used as a core material of the vacuum heat insulating material and the degree of vacuum is about 0.1 to 0.01 mmHg.

FIG. 3 illustrates a conventional method for manufacturing a heat insulating material. As shown in the figure, a foamed resin 1 such as a hard polyurethane resin is present inside a box 2 and has independent or open cells 3 during a curing reaction. The heat insulating material 4 is formed by expanding while forming a large number of particles and filling the box body 2. Reference numeral 5 denotes a skin layer which is necessarily formed along the wall of the box 2 during the curing reaction or on the upper surface of the heat insulating material 4.

[0006]

However, the heat insulating material produced by the above-mentioned conventional manufacturing method is high in cost because of a complicated structure such as a double structure heat insulating body made of an inorganic heat insulating material and a hard polyurethane foam. By reacting and foaming a foamed resin 1 such as a hard polyurethane resin in the inside of the box body 2, a skin layer 5 is formed on the contact surface side with the box body 2, and the skin layer 5 has air bubbles formed therein. There is a problem that the heat insulation is poor because the resin layer is not present. Therefore, when it is used as a vacuum heat insulating material, the skin layer 5 is cut off and used, which requires a troublesome work of cutting and wastes the material.

The present invention is intended to solve the above problems,
It is an object of the present invention to provide a method for producing a heat insulating material which has excellent volumetric heat insulating efficiency and can effectively utilize the material.

[0008]

In order to achieve the above object, the present invention fills a container having an opening at one end, a breathable bottom at the other end, and a breathable wall around it with a foaming resin, Simultaneously with the start of the curing reaction, the pressure around the opening of the container, the air permeable bottom and the air permeable wall is controlled to form continuous air bubbles inside the expandable resin.

[0009]

According to the present invention, therefore, it is possible to adjust the pressure applied to the upper opening portion of the container filled with the foamable resin and the air permeable bottom portion facing the opening portion, and the pressure applied to the periphery of the air permeable wall body. Thus, it is possible to form communicating air bubbles having an arbitrary shape inside the obtained heat insulating material. Also, by changing the shape of the container arbitrarily, or by making the pressure applied to the opening and the air permeable bottom different from the pressure applied to the periphery of the air permeable wall, the communication formed inside the foamable resin can be improved. The air bubbles can be provided with major and minor axes of any size. Further, since the container is breathable, it is possible to prevent the skin layer from being formed on the outside of the foamable resin formed, or at least to make the thickness of the skin layer extremely thin, so that the material can be effectively used.

[0010]

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

1 and 2 illustrate a method of manufacturing a heat insulating material according to an embodiment of the present invention. In FIG.
Is a container including an opening 7, an air permeable bottom portion 8 facing the opening 7 and an air permeable wall body 9. Inside the container 6, a foaming resin 10 made of hard polyurethane resin or the like is provided in the opening 7. Filled from. Next, while maintaining the curing reaction temperature, the polymerization reaction of the hard polyurethane resin 10 is promoted to form a large number of communicating air bubbles 11 inside the hard polyurethane resin 10 to obtain the heat insulating material 12.

In the above manufacturing method, the container 6 is placed in a decompression container 15 having two pressure adjusting chambers 13 and 14, and a pressure T ₁ is applied to the opening 7 and the air permeable bottom 8 of the container 6 and a gas permeable property. A pressure T ₂ can be applied to the periphery of the wall body 9, and T ₁ and T ₂ can be controlled to arbitrary pressures. Therefore, during the curing reaction, the hard polyurethane resin 10 expands while forming the communicating air bubbles 11, the pressure T ₁ is applied to the opening 7 and the air permeable bottom 8, and the pressure T ₂ is applied around the air permeable wall 9. For example, when T ₁ and T ₂ are depressurized, they are subjected to different suction forces, and the degree of depressurization makes it possible to give the communicating bubble 11 an arbitrary major axis and minor axis.

FIG. 1 shows a heat insulating material 12 obtained in the first embodiment of the present invention, in which the height h of the air permeable wall 9 and the length l of the air permeable bottom 8 and the opening. 7 and the degree of pressure reduction T _{1 in the} direction of the breathable bottom portion 8 and the degree of pressure reduction T _{2 in the} direction of the breathable wall body 9 are h> l and T ₁ > T ₂ , respectively. It is formed in a shape having a long axis in the direction of the opening 7 and a short axis in the direction of the breathable wall body 9.

Next, FIG. 2 shows a heat insulating material 12 obtained in the second embodiment of the present invention. In this case, the relationship between h and l and T ₁ and T ₂ is h <l, T _{1 as well.} <T ₂ , so that the communicating air bubbles 11 are formed in a shape having a major axis in the direction of the air-permeable wall 9 and a minor axis in the direction of the opening 7. In addition, since the air-permeable bottom portion 8 and the air-permeable wall body 9 in contact with the heat insulating material 12 are constantly depressurized during the reaction curing, a continuous air bubble cannot be formed, that is, a so-called skin layer does not occur. Or even if it occurs, it becomes an extremely thin film, and the waste of material can be eliminated.

The sizes of the major axis and the minor axis of the communicating air bubbles 11 can be controlled by changing the relationship between h and l and T ₁ and T ₂ , respectively. In the above embodiment, T
The case where ₁ and T ₂ are negative pressures has been described, but it is also possible to control the pressure difference by setting positive pressures in which T ₁ and T ₂ are different or one is positive pressure and the other is negative pressure. It is determined by the component composition of the resin composition 10 or physical conditions such as curing reaction conditions and viscosity. As described above, according to the above-described embodiment, the height h of the air permeable wall body 9 is set to the length l of the air permeable bottom portion 8 when the hard polyurethane resin 10 is hardened and the communicating air bubbles 11 are formed therein. Since the pressure T ₁ in the direction of the opening 7 is made higher than the pressure T _{2 in the} direction of the breathable wall 9, a large number of communicating air bubbles 11 having a long axis in the direction of the opening 7 are formed. The heat insulating material 12 can be obtained.

As described in Japanese Patent Publication No. 63-61589 filed by the applicant of the present patent application, the composition of the foamable resin 10 is mainly composed of a hard polyurethane resin such as organic polyisocyanate. By using a mixture of a polyol, a catalyst, a foaming agent, a bubble communicating agent, a foam stabilizer and a silicone-based surfactant as other components, the communicating air bubbles 11 can be obtained more easily. it can.

[0017]

As is apparent from the above embodiments, according to the present invention, a container having an opening at one end, a breathable bottom at the other end, and a breathable wall around it is filled with a foaming resin such as polyurethane. By controlling the pressure around the opening of the container, the air permeable bottom and the air permeable wall at the same time when the curing reaction starts, a large number of open air bubbles having a long axis and a short axis are formed in the obtained heat insulating material. Since it is possible to prevent or suppress the formation of a skin layer that cannot be used as a heat insulating material, the material can be effectively used and a heat insulating material having an excellent heat retaining effect can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a method of manufacturing a heat insulating material according to a first embodiment of the present invention.

FIG. 2 is a sectional view for explaining a method for manufacturing a heat insulating material in the second embodiment.

FIG. 3 is a sectional view for explaining a conventional method of manufacturing a heat insulating material.

[Explanation of symbols]

 6 Container 7 Opening 8 Breathable Bottom 9 Breathable Wall 10 Hard Polyurethane Resin (Foaming Resin) 11 Open Air Bubbles

Claims (4)

[Claims] 1. A container having an opening at one end and an air-permeable bottom at the other end facing the opening and an air-permeable wall around it is filled with a foaming resin, and at the same time when the curing reaction starts, A method for producing a heat insulating material, wherein continuous air bubbles are formed inside the expandable resin by controlling the pressures of the opening and the air permeable bottom and the pressure around the air permeable wall. 2. The method for producing a heat insulating material according to claim 1, wherein the communicating air bubbles have a shape having a long axis and a short axis. 3. The method for producing a heat insulating material according to claim 1, wherein the pressure applied to the opening of the container and the air permeable bottom facing the opening is different from the pressure applied to the periphery of the air permeable wall of the container. 4. The method for producing a heat insulating material according to claim 1, wherein the foamable resin is mainly composed of a hard polyurethane resin.