JPH04351396A - Manufacture of vacuum heat insulating wall - Google Patents

Abstract

PURPOSE:To offer the manufacturing method of the heat insulating wall which is able to insulate heat to a high degree and also can be manufactured easily. CONSTITUTION:The inorganic binder, in which radiation preventive is distributed uniformly, is included in the heat insulating inorganic fiber 2, which is in a non-pressurized swelled state. The inorganic fiber mat 2A, which has been dried and hardened by being compressed by the pressure equal to the atmospheric pressure with respect to the vacuum until the thickness is nearly equal to the clearance of the heat insulating space of the heat insulating wall, is inserted into the heat insulating space 1. Then, the inside of the heat insulating space 1 is evacuated to the vacuum. By this constitution, it is possible to give the pressure resistivity of the heat insulating wall by the compressed inorganic heat insulating mat 2A, and also to perform the evacuation easily, and further, to improve the heat insulating effect.

Description

Description: FIELD OF INDUSTRIAL APPLICATION This invention relates to a method for manufacturing a vacuum heat insulator. [0002] Conventionally, as a structure of an insulating wall that provides high-level insulation in baking ovens for heat treatment, etc., the inside of the insulating wall consisting of the inner and outer walls is made into a sealed space, and the inside is densely filled with inorganic foam powder, and then the inside is evacuated. A heat insulating wall is known (for example, Japanese Patent Publication No. 60-8399). This type of insulation wall has a high-order insulation effect due to the synergistic effect of the internal vacuum atmosphere and the insulation effect of the densely packed inorganic foam powder, and for example, a wall with a thickness of about 4 to 5 cm Room temperature and 300~4
It is said that it is possible to insulate a temperature difference of 0.00°C. [Problems with the prior art] However, with the above-mentioned heat insulator, it is very troublesome to densely fill the powder into the heat-insulating space, and this difficulty becomes even more pronounced when the heat-insulating wall has a complicated shape. Even if filling was possible, there were various problems such as powder being inevitably sucked during vacuum evacuation and complicated filters being required to minimize this. [0004] In order to solve this problem, a mat made of inorganic fibers is housed in a heat insulating space, and then the mat is evacuated and sealed (for example, as described in Japanese Utility Model Application No. 62-54396).
(Japanese Patent Application Laid-open No. 78991/1982), or storing an inorganic fiber mat mixed with a radiation prevention material, etc., and then vacuuming and sealing it (for example, Japanese Patent Application Laid-open No. 78991/1989). However, in the former case, the mat When the insulation wall is evacuated after being filled with fiber mat, there is a problem that the insulation wall may be deformed in a concave manner due to the uneven filling degree of the fiber mat or the compressive deformability of the fiber mat.In the latter case, radiation between the fibers may cause Since the preventive material and the like are not firmly fixed, there is a problem in that the powdered radiation preventive material and the like fall and accumulate over a long period of time, resulting in uneven distribution of the heat insulating effect. SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made for the purpose of providing a method for manufacturing a heat insulating body that is capable of high-level heat insulation and is easy to manufacture. be. [Means for Solving the Problems] That is, the method for manufacturing a vacuum heat insulating body of the present invention includes adding an inorganic binder in which a radiation preventing material is uniformly dispersed to heat insulating inorganic fibers in a non-pressure swollen state. , the impregnated insulation inorganic fibers are compressed at a pressure equal to the atmospheric pressure relative to the vacuum to a thickness approximately equal to the insulation space of the insulation wall, and an inorganic fiber insulation mat that is hardened and dried is inserted into the insulation space. The apparatus is characterized in that the inside of the adiabatic space is evacuated. [Operation] The heat insulating wall that is the object of this invention has a structure in which the front and back surfaces are membranes, and the space between them is a closed space for heat insulation. The main structure for insulation is that the insulation wall is filled with an insulation material made of inorganic fibers such as glass fiber or rock wool, and the inside is evacuated. Prior to filling, an inorganic binder with a radiation prevention material uniformly dispersed therein, such as colloidal silica, alumina sol, cement, bentonite, etc.
The material used is impregnated with fly ash, etc., compressed at a pressure approximately equal to the difference between vacuum and atmospheric pressure, and hardened and dried to a thickness that can be stored in an insulated space. Therefore, storing it in the heat insulating space is like inserting a plate-like body, which makes insertion very easy. [0008] After that, if the inside of the heat insulating wall is sealed and evacuated, the concave deformation of the membrane due to atmospheric pressure is supported by the shape stability of the compressed and inserted inorganic fibers. At the same time, since the internal inorganic fibers are in a hardened and fixed state during the evacuation operation, there is no fear of suction and evacuation, and the evacuation can be performed easily and in a short time. In the above, radiation prevention materials include heat reflective materials such as aluminum foil and copper foil, heat absorbing materials such as carbon black, or heat absorbing materials such as metal oxides such as TiO2 and Fe3O4, carbides, nitrides, and magnetite. Scatter material is used. Furthermore, from the viewpoint of heat insulation efficiency, inorganic fibers having a fiber diameter of 4 to 15 μm, preferably 8 μm are used. [Example] Next, an example of the present invention will be described. 1 to 4 are a perspective view and a sectional view showing steps for implementing the present invention. Example 1 Rutile sand (
After adding 50 parts by weight of TiO2 and mixing uniformly, water was added at a weight ratio of 1 to 10 parts of colloidal silica to make a diluted solution, and a thick glass fiber mat 2 made of glass fibers with a fiber diameter of 5 μm to 8 μm was produced in a non-pressurized state. impregnated with. Next, the impregnated glass fiber mat 2 is pressed in a press at a pressure of 1 kg/cm2 until it reaches a thickness of 3 cm (Fig. 1).
Pressure was applied as shown by the dotted line, and the material was cured and dried while still in the mold. Next, stainless steel membranes with a thickness of 0.5 mm were used as the inner and outer walls 1A and 1B, and the thickness of the insulation space was set to 30 mm.
Insert the impregnated compressed mat 2A through the opening 3 provided at the upper end into the insulation wall 1 of the container, which has the insulation wall 1 (FIG. 2) with a diameter of It was sealed tightly. Next, the container having this insulating wall 1 is placed in a baking oven 4 as shown in FIG.
．． After heating for 5 hours and discharging unnecessary gas, vacuum pump 8
was operated to evacuate the inside of the heat insulating wall 1, and after the vacuum was completed, the suction port was sealed to obtain a container having the heat insulating wall 1 shown in FIG. Example 2 A container having a heat insulating wall 1 was produced in the same manner as in Example 1, except that rock wool having an average fiber diameter of 5 μm was used in place of the glass fiber mat used in Example 1. Example 3 A plurality of impregnated glass mats 2 obtained in Example 1 were layered with aluminum foil sandwiched between them, and pressed together using a press.
A container having a heat insulating wall 1 was manufactured in the same manner as in Example 1 except that it was compressed at a pressure of kg/cm2. When the external appearance of the heat insulating walls of Examples 1 to 3 was observed, no concave deformation occurred on the surface. Further, when the external appearance of the heat insulating walls of Examples 1 to 8 was observed during the heat insulation test, no concave deformation of the surface was observed. Further, when the thermal conductivity was measured according to ASTM C518-85, the results shown in the table were obtained. [0016]
table
Thermal conductivity Pumping time
Deformation amount Example 1 0
．． 0025 3.0 〃
0% 〃 2
0.0032 3.2 〃
0〃〃3
0.0018 2.8
〃 0〃 Comparative example 1 0.0083 45
〃 10〃
〃 2 0.0028
2.4 〃 20〃 [
In the table, Comparative Example 1 is a conventional insulating wall filled with inorganic foam powder, and Comparative Example 2 is a heat insulating wall filled with rock wool that does not use an inorganic binder, a heat scattering material such as rutile sand, or a radiant material. Also, the exhaust time is 0.05T
The exhaust time required to orr and the amount of deformation are 0.05
The amount of concave deformation of the central portion of the heat insulating wall when the vacuum is evacuated to Torr is expressed as a percentage of the original thickness. As is clear from the table, it was found to be superior to the conventional example in terms of thermal conductivity, evacuation time, and deformation prevention effect. [0017] As explained above, according to the present invention, it is very easy to fill the insulating material into the insulating wall, and the insulating material to be filled is once compressed at atmospheric pressure. Since it is used, sufficient pressure resistance can be exerted inside the heat insulating wall, and even a heat insulating wall made of a thin membrane can be prevented from being deformed. In addition, it has various effects such as the degree of vacuum inside can be easily achieved, and together with the insulation properties of glass fibers, even thin insulation walls can provide sufficient insulation properties, which can contribute to making insulation containers more compact. .

[Brief explanation of drawings]

FIG. 1 is a perspective view of an inorganic fiber mat according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a container with an insulating wall according to an embodiment of the invention.

FIG. 3 is a sectional view showing the baking state of the container according to the embodiment of the present invention.

FIG. 4 is a sectional view of a heat-insulating container obtained by the method of the present invention.

[Explanation of symbols]

1 Insulated wall 2 Glass fiber mat 2A Compressed mat 3 Opening 4 Baking oven 5 Suction port 6 Exhaust port 7 Valve 8 Vacuum pump

Claims (1)

[Claims] [Claim 1] A heat insulating inorganic fiber in a non-pressure swollen state,
An inorganic binder with a radiation prevention material uniformly dispersed therein is contained, and the impregnated inorganic fibers are compressed at a pressure equal to atmospheric pressure relative to a vacuum to a thickness approximately equal to the insulation space of the insulation wall, and then hardened and dried. A method for manufacturing a vacuum heat insulating wall, comprising inserting the inorganic fiber heat insulating mat into the heat insulating space, and evacuating the inside of the heat insulating space.