JPH10337738A - Manufacture of heat insulated panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the generation of voids to a large extent and particularly eliminate the generation of voids adjacent to the inner faces of two surface plates when a raw material liquid of isocyanurate foam is injected and foamed, in the manufacture of a heat insulated panel. SOLUTION: When a raw material liquid of isocyanurate foam 3 is injected and foamed in a space formed by two surface plates 1 facing each other and frame materials interposed between respective side sections of the surface plates, foaming is carried out without voids in the whole of the above space, and then the raw material liquid of 40-100% or more is further injected into the above raw material liquid without generating the increase of concentration of the isocyanurate foam 3 when the total amount of the above raw material liquid is set as 100%, or the raw material liquid of concentration of 50-80 kg/m<3> is injected therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat insulating panel constituting a prefabricated refrigerator, freezer, environmental test room or clean room, and more particularly, to a method for manufacturing using an isocyanurate foam as a heat insulating material. It is about.

[0002]

2. Description of the Related Art When manufacturing a heat insulating panel, platens that can be heated by an electric heater or the like are piled up at regular intervals via spacers, and the platens are vertically opposed by a jig.
A plurality of surface plates are arranged, and a frame material is interposed between each side of these surface plates, and a raw material liquid of the isocyanurate foam is injected into a space formed by each frame material and the two surface plates. To form a heat insulating layer.

[0003]

However, in the above-mentioned production method, voids (voids) are easily generated in the heat insulating layer formed by injection and foaming of the raw material liquid of the isocyanurate foam, and particularly, the voids are formed adjacent to the inner surface of each surface plate. And the tendency to occur was strong. Therefore, when the manufactured heat insulating panel is used for a refrigerator or an environmental test chamber, etc., the gas in the void expands and contracts, and local swelling and depression occur on both surface plates. There is a problem that the surface plate is remarkably damaged and the surface plate is peeled off and the heat insulation performance is deteriorated.

[0004] In addition, the applicant has previously obtained a patent for a method of manufacturing a heat insulating panel using a urethane foam as a heat insulating material and injecting a predetermined amount of a raw material liquid under a predetermined condition to foam the liquid. (Patent No. 255262
No. 3), compared to the urethane bond formation reaction that occurs during the formation of the urethane foam, the triazine ring formation reaction due to isocyanate trimerization that occurs during the isocyanurate foam formation is less likely to start, so urethane foam injection foaming The preheating temperature of the heating platen is usually
It is necessary to set about 20-30 ° C higher, and once
When the formation reaction of the triazine ring starts, it proceeds rapidly. Therefore, when the production method using the urethane foam is applied to panel production using an isocyanurate foam, as shown in FIG. 6, two surface plates (1) are used.
The advancing speed (V ₁ ) of the injected and foamed raw material (3a) near the inner surface of the material is determined by the contact resistance between the raw material (3a) and the surface plate (1) in this portion, and the advancing speed of the injected and foamed raw material (3b) in the middle layer. (V ₂ ), and as shown in FIG. 7, as a result, a large number of voids (4) are likely to be generated after foaming, especially adjacent to the inner surfaces of both face plates (1). This causes a large number of local bulges and depressions of the both surface plates described above.

SUMMARY OF THE INVENTION It is an object of the present invention to significantly reduce the number of voids generated when an isocyanurate foam raw material liquid is injected and foamed, and to provide heat insulation in which voids are not generated especially adjacent to the inner surfaces of two face plates. An object of the present invention is to provide a panel manufacturing method.

[0006]

According to a first aspect of the present invention, there is provided an isocyanate in a space formed by two facing surface plates and a frame material interposed between respective sides of the surface plates. When the raw material liquid for the nurate foam is injected and foamed, the raw material liquid is further added to the raw material liquid in an amount of 40 to 100, with the amount of the raw material liquid which is foamed without gaps in the entire space and does not accompany the subsequent increase in density of the isocyanurate foam as 100%. %
It is characterized by excessive injection.

[0007] The raw material liquid of isocyanurate foam is
% Does not provide a significant effect of reducing voids, etc., and excessively injecting more than 100% does not significantly improve the effect of reducing voids. Since the injection foaming of the material tends to be difficult to perform, the above range is from 40 to 100%.

According to the present invention, a raw material liquid for an isocyanurate foam is placed in a space formed by two facing surface plates and a frame material interposed between each side of the surface plates. Injecting and foaming, the raw material liquid is injected at a density of 50 to 80 kg / m ³ .

[0009] Even if the raw material liquid for the isocyanurate foam is injected at a density of less than 50 kg / m ³ , a significant effect of reducing voids cannot be obtained, and if the raw material liquid is injected at a density exceeding 80 kg / m ³ , Since the cost becomes too high and the heat insulating performance of the panel starts to decrease, the density is increased to 50 to 80.
kg / m ³ .

It is needless to say that the present invention may be carried out so as to satisfy both requirements of the inventions.

[0011]

Next, an embodiment of the present invention will be described. The surface plates are stacked at regular intervals via spacers, and two metal surface plates (900 × 3000 mm) that are vertically opposed by a jig are arranged between each surface plate, and between each side of these surface plates. After a space is formed between each frame material and two surface plates with a frame material interposed therebetween, the platen is heated to about 60 ° C. in advance by an electric heater, and in this state, as shown in FIG. Then, a raw material liquid of isocyanurate foam adjusted to 25 ° C. is injected from the center of the length of the two surface plates (1) to the space between the two surface plates (1) under the conditions shown in Table 1 below and foamed. I let it.

[0012] In Table 1, the pack ratio is 2
Injecting and foaming the isocyanurate foam raw material liquid into the space formed by the two face plates and the frame material interposed between the respective side portions of these face plates, In addition, the injection amount of the raw material liquid without increasing the density of the isocyanurate foam after that is 100
%. The injection density refers to the density at which the raw material liquid for the isocyanurate foam is injected into the space. The panel appearance evaluation is an appearance evaluation based on a bulge, a dent, or the like seen in a surface plate of a heat insulating panel manufactured by injection foaming, and is set in the following five stages.

5: There are no local bulges or dents at all 4: 若干 Somewhat 3: 〃 Some 2: 〃 Many 1: Many local bulges or dents and large undulations

[Table 1] As shown in the panel appearance evaluation shown in Table 1, the comparative example had a local swelling or depression, whereas Embodiments 1 to
In No. 3, no swelling or depression was observed.

Next, as shown in FIG. 1, the thermal insulation panel (2) of each of the above embodiments and the comparative example will be described.
Is cut from the left end to the center of the width of the panel by 50 mm to form 1 to 30 measurement sections, and measure the number of voids found on the cut surfaces (A1) to (A30) in each measurement section. At the same time, the state of generation of voids was also observed.

The void to be measured has a diameter of 5 m.
m or more.

FIG. 2 shows the first embodiment (pack ratio 160%).
And the cut surface of each panel in the comparison form (pack ratio 125%) (A
In (1) to (A30), numerical values obtained by adding the number of voids of the cut surface by two in order are shown, and FIG. 3 shows the total number of voids in each panel.

When comparing the number of voids of each of the heat insulating panels of the first embodiment shown in FIGS. 2 and 3 and the comparative embodiment,
It can be seen that the number of voids in the panel of the first embodiment is reduced by half as compared with the panel of the comparative embodiment. Further, even in the state of occurrence of voids, as shown in FIG.
In the isocyanurate foam layer (3), voids (4)
In the panel of Embodiment 1, as shown in FIG. 5, voids (4) are generated small at a position distant from the surface plate (1). It was confirmed that an isocyanurate foam layer (3) was present between the void (4) and the face plate (1) at a constant thickness. Therefore, Embodiment 1
According to the above, even when the number of voids is significantly reduced and voids are generated, the voids are generated at a small distance from the surface plate (1), so that local swelling or depression of the surface plate (1) is completely eliminated. Does not occur. The same test was performed on the heat insulating panels according to the second and third embodiments, and the same result as that of the first embodiment was obtained.

The above test results are consistent with the panel appearance evaluation in Table 1 above.

[0019]

According to the first and second aspects of the present invention, the number of voids can be greatly reduced as compared with the conventional method, and the voids are generated at a position distant from the surface plate. And the void itself can be reduced. Therefore, even when the heat-insulating panel is used for a refrigerator or an environmental test room, local expansion and depression of the surface plate due to expansion and contraction of gas in the voids are reliably prevented, and the appearance of the panel is kept beautiful. In addition, there is no problem that the strength of the heat insulation panel as a whole is increased, and the peeling of the surface plate and the deterioration of the heat insulation performance are caused.

In addition, there is also a practical advantage that any of the methods of the present invention described in claims 1 and 2 can be carried out using existing equipment as it is.

[Brief description of the drawings]

FIG. 1 is a front view of a heat insulating panel.

FIG. 2 is a graph showing the number of voids in each of two measurement sections in each panel of the first embodiment and a comparative example.

FIG. 3 is a graph showing the total number of voids in each panel shown in FIG. 2;

FIG. 4 is a vertical sectional view showing a state of occurrence of voids in a heat insulating panel of a comparative embodiment.

FIG. 5 is a vertical sectional view showing a state where voids are generated in the heat insulating panel of the first embodiment.

FIG. 6 is a vertical sectional view of a panel showing a state at the time of injection and foaming of a conventional isocyanurate foam.

FIG. 7 is a vertical sectional view of the panel after the injection foaming of FIG. 6;

[Explanation of symbols]

 (1): Surface plate (2): Thermal insulation panel (3): Isocyanurate foam layer

Claims (2)

[Claims] 1. Injecting and foaming a raw material liquid of isocyanurate foam into a space formed by two facing surface plates and a frame material interposed between respective side portions of these surface plates, Assuming that the injection amount of the raw material liquid which is foamed without gaps in the entire space and does not increase the density of the isocyanurate foam thereafter is 100%, the raw material liquid is further reduced by 40%.
A method for producing a heat insulating panel, characterized by injecting 100 to 100% excess. 2. Injecting and foaming a raw material liquid for isocyanurate foam into a space formed by two facing surface plates and a frame material interposed between respective side portions of these surface plates, A method for producing a heat insulating panel, comprising injecting a raw material liquid at a density of 50 to 80 kg / m ³ .