JPS6213978A - Manufacture of heat-insulating box body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a heat insulating box for use in refrigerators, etc., in which a foamed heat insulating material such as hard urethane foam is integrally foamed between an inner box and an outer box.

Conventionally, the hard urethane foam raw material injected between the inner box and the outer box was foamed by a foaming/polymerization reaction, and then filled between the two boxes to form an insulating box. The polymerization reaction progresses as time passes after the injection of hard urethane is started, resulting in a highly viscous fluid foam especially near the final filling part between the two boxes. As a result, the flow resistance between the inner box and the outer box was large, and the tip of the fluid foam body caused turbulent flow, causing gas accumulation to occur on the inner surfaces of both boxes. This gas pool replaces the fluorocarbon gas contained in the hard urethane foam.
At low temperatures, the gas liquefies and the pressure drops, causing the inner and outer boxes to become deformed, which is a very serious problem.

Conventionally, the solution to this problem was to attach a sheet with a ventilation layer, such as soft urethane foam, to the inner surface of the inner and outer boxes near the end of filling with the insulation material, such as hard urethane foam, using adhesive. . However, this method not only requires a large number of parts and expensive materials, but is also difficult to work with.

In particular, the present invention is an insulating box that easily eliminates deformation during cooling due to the above-mentioned gas accumulation without increasing the number of parts, especially in the inner box of a heat insulating box made of thermoplastic resin such as MuBS by vacuum forming. The purpose is to provide the following.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is an inner box 2 made of thermoplastic resin in a vacuum.
, an outer box 3 made of iron plate υ, and a heat insulating material 4 made of hard urethane foam filled between the two boxes. Reference numeral 6 denotes two symmetrical injection ports arranged on the back side of the outer box 3, into which the hard urethane foam raw material is injected from the foaming machine head 6. Air vent holes 9 are formed in the back wall of the outer box 3. In the vicinity of the final filling part of the hard urethane foam raw material on the back side of the inner box 2 facing the back wall of the outer box 3, there is a distance of 301rII or less to a depth of 1 mm in the direction transverse to the filling direction of the urethane foam raw material.
The unevenness 7 of about 6ff to 3.off is formed during vacuum forming.

In such a device, the hard urethane foam raw material of the heat insulating material 4 is supplied from the foaming machine head 6 through the injection port 6 provided in the outer box 3.
When the hard urethane foam raw material is injected between the inner box 2 and the outer box 3 via the While doing so, start filling. Furthermore, as the foaming and polymerization reactions progress over time, the hard urethane foam fluid becomes highly viscous, resulting in a large flow resistance with the inner surface of the inner box 2 and a turbulent flow at the tip of the fluid. wake up,
A gas pocket 8 begins to form. The gas pocket 8 formed in such a process becomes large, 30NM or more. Then, this gas reservoir 8 is replaced with fluorocarbon gas contained in the hard urethane foam, and when cooled to below the boiling point of the fluorocarbon gas, the fluorocarbon gas liquefies, and the inside of the gas reservoir 8 becomes a vacuum state. As a result, the thin portion of the inner box 2 vacuum-formed from thermoplastic resin or the like lacks rigidity and deforms along the shape of the gas reservoir 8. but,
As described above, in the present invention, the unevenness 7 is formed transversely to the filling direction of the urethane foam raw material at intervals of 30 nm or less near the final filling part of the heat insulating material such as the hard urethane foam. When the tip of the fluid passes over the unevenness 7, the gas pool 8 is divided into small pieces. The size of the gas reservoir 8 is elongated along the unevenness 7, and if the interval between the unevenness 7 is 3 o 1 r II or less, the size of the gas accumulation 8 can be regulated to 30 mm or less. In other words, as shown in Fig. 4 (because the size of the gas reservoir 8 is small, the deformation l is small even if the inner box 2 is thin, and the reinforcing effect by the step of the unevenness 7 is also good, and furthermore, there is no deformation to some extent. Even if it does occur, it will be less noticeable due to the presence of the unevenness 7, and the problem in appearance can be solved.The length of the unevenness 7 does not have to be continuous as it is cut in the middle, and the length of the unevenness 7 does not have to be continuous. The point of .5 aot is due to the limit of the reinforcing effect of the inner box 2, and the point of 3.0111 is the limit to avoid foaming resistance of the heat insulating material.

As described above, the present invention provides a method for integrally foaming a foamed heat insulating material such as a hard urethane foam between an outer box and an inner box made of a thermoplastic resin. This type of foam insulation material has irregularities formed transversely to the filling direction of the foam insulation material, which can easily reduce the size of gas pockets that occur at the final filling part of the foam insulation material without increasing the number of parts. To provide a heat insulating box body which eliminates deformation due to the reinforcing effect of the inner box.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a heat insulating box according to an embodiment of the present invention, Fig. 2 is a cross-sectional view showing the filling state of the heat insulating material, and Fig. 3 is a diagram showing the shape of the inner box at the final part filled with urethane. The external view, FIG. 4, is a cross-sectional view of FIG. 3 1-1'. 2...Inner box, 3...Outer box, 4...
...Insulation material, 7...Irregularities. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A plurality of irregularities are formed in a direction transverse to the filling direction of the insulation material near the final filling point of the foam insulation material in the inner box made of thermoplastic resin, and the foam insulation material is integrally foamed between the inner box and the outer box. A method for manufacturing a heat-insulating box.