JPH0272293A - Heat insulating structure - Google Patents

Abstract

PURPOSE:To shorten the exhaust time so as to enable mass production to be attained by coating a hard quality phenol urethane foam of open cell structure with a vessel of metal-plastic laminated film and reducing a pressure in the inside to close it. CONSTITUTION:A hard quality phenol urethane foam 4 of open cell structure, obtained by using benzylic ether type phenol resin of 400 to 600mgKOH/g hydroxyl group value, organic polyisocyanate, catalyst, bubble arranging agent, foaming agent and a bubble communication agent, is used for a heat insulating structure 6 as its core member. By the constitution thus obtained, the core member, because it is of fine foam framework, is coated with a vessel 5 formed by a metal-plastic laminated film, when a pressure in the inside is reduced, excellent heat insulating performance is obtained even by a pressure of about 0.1 to 0.01mmHg easy to handle industrially, and mass production efficiency is substantially improved by shortening the exhaust time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat insulator used in refrigerators, frozen prefabricated products, and the like.

BACKGROUND OF THE INVENTION FIG. 3 shows a conventional heat insulator. The configuration of the conventional example will be explained below with reference to FIG.

In recent years, attention has been paid to the use of a heat insulating body with a reduced internal pressure in order to improve the heat insulation performance of the heat insulating box. As the core material of this heat insulating body, powder such as perlite, honeycomb, foam, etc. are used. For example, JP-A-57-1338
As shown in Japanese Patent No. 70, a proposal has been made to use a hard urethane foam having open cells as a core material. This Japanese Patent Application Laid-open No. 57-133870 is explained using Fig. 3.
In the figure, 1 is a heat insulating structure, 2 is a hard urethane foam having open cells, and a container 3 is made of an airtight thin film.
The hard urethane foam 2 has a cell skeleton diameter of 3.
The feature is that a commercially available general material with a size of about 0 to 100 μm is vacuum degassed under high temperature and high humidity to break the bubbles and obtain open cells.

Problems to be Solved by the Invention In such a heat-insulating structure 1, since the bubble skeleton diameter of the rigid foam 2 is 3oO to 1000 μm, the heat conduction of the gas must be maintained at a pressure of 0.001 W Hq or less. The ratio is not sufficiently small, and excellent heat insulation properties cannot be obtained. Basically, the thermal conductivity of a gas decreases rapidly when the distance between the walls of the gas layer (in this configuration, the bubble skeleton diameter) becomes shorter than the mean free path of the gas, but as the distance between the walls becomes longer, the same Lower pressures are required to obtain gas thermal conductivity. The general formula is represented by the following formula (1).

Ky=A-p-V・CrCLf-d/(Lf+d))
...-(1) A: Constant ρ: Density (Ks+/i) V: Average molecular velocity Cm/s:] Lf: Mean free path Cr: Constant volume specific heat (ksl/Kp″C) d: Distance between walls (m) Therefore, in the conventional example, the bubble skeleton diameter is 300 to 10
00 μm, a pressure of 1 o g Hg or less, which is difficult to handle industrially, is required, which poses problems such as the need for large-scale equipment and long evacuation time in mass production. Furthermore, in the pressure range of 10 mmHq or less, it is easily affected by the amount of gas released by the material, and in the case of this organic composition that tends to contain low molecular weight monomer components, there is a problem that the evacuation time is particularly long, which reduces mass production efficiency. It was bad.

The present invention solves the above-mentioned problems by achieving excellent heat insulation performance in a low vacuum range that is industrially easy to handle, thereby shortening the evacuation time and making mass production possible.

Means for Solving the Problems The present invention uses a benzylic ether type pheno-yv resin with a hydroxyl value of 400 to eoomgKOH/9, an organic polyisocyanate, a catalyst, a foam stabilizer, a foaming agent, and a cell communication agent. This is a hard phenolic urethane foam with open-cell groove structure that is used as the core material of the heating element.

Function The present invention has the above-mentioned structure, and since the core material has a fine cell skeleton,
This core material is covered with a container made of metal-plastic laminate film, and when the inside is reduced in pressure, the pressure is reduced to 0.1 to 0.
Excellent heat insulation performance can be obtained even at an industrially easy-to-handle pressure of about 0.01 w Hg, and by shortening the evacuation time, mass production efficiency can be greatly improved.

EXAMPLE Hereinafter, an example of the present invention will be explained with reference to FIG. 1 and FIG. 2.

In the figure, 4 is a hard phenol urethane foam that was foamed in a high-pressure urethane foaming machine using the raw materials shown in Table 1, cured, aged at room temperature, and then cut into a predetermined size.

Table 1 In Table 1, resins A and B are benzylic ether type phenolic resins, and resin A has a hydroxyl value of 4 s Omy.
KOH/', j9, vno, /B has a hydroxyl value of 50
Q: 119KOH/'g. The foam stabilizer is Shin-Etsu Chemical Co., Ltd.'s cyclic silicone surfactant F-373, and the foaming agent is Showa Denko ((1) Freon R-1j, Touch i1 is Dimenal Eta 5.
The nolamine and the bubble communication agent are calcium stearate manufactured by NOF Corporation. Arihiro - Cory boar, 2':
, -) is crude di-fermethane diisonanate (amine equivalent: 136) manufactured by Nippon Polyurethane Co., Ltd. Resin C and Resin D used as comparative examples are benzylic ether type phenolic resins, and Resin C has a hydroxyl value of 3.
ao rruj KOH/, q, Resin D has a hydroxyl value of 610 KOH/, 51'. Various combinations of these raw materials are used for foaming, and some of them are used as examples.
．． 4 (z 1 , -hx 2, as a comparative example 1.・A
, 7ffi B, and 7fa C. Table 2 shows the density, open cell ratio, cell skeleton diameter, and compressive strength of the obtained hard phenolic urethane foam 4. Thereafter, the obtained rigid urethane foam 4 is heated at 150° C. for about 2 hours to evaporate the adsorbed water and swelling gas, and is covered with a container 5 made of aluminum-deposited polyester film, so that the inside is covered with a 0.
001, 0.01, 0.1, 0.5.1, Om
The pressure was reduced to xHq and the heat insulator 6 was obtained. The evacuation time at this time was 35 minutes for both the example and the comparative example.

They were 6 minutes, 2 minutes, and 1 minute 30 seconds. The thermal conductivity of the obtained heat insulator 6 immediately after sealing is also shown in Table 2. The thermal conductivity was measured using K Matic manufactured by Shinku Riko Co., Ltd. at an average temperature of 24.
Measured at °C.

As is clear from Table 2, the hydroxyl value is 400 to 600 #
KOH/jJ (7) Benzylic ether type phenolic resin and organic polyisocyanate, catalyst 9 blowing agent,
Continuous fffi E obtained using a foam stabilizer and a cell opening agent
It was found that the hard phenol urethane foam 4 with a foam structure has a very fine cell skeleton, and a foam with excellent dimensional stability can be obtained without problems such as foam shrinkage, flyability, and E. - Hydroxyl value is 400
~KOH/, Resin C which is less than 9 has a low foam compressive strength, and the foam shrinks under reduced pressure and lacks dimensional stability.If the density is increased to ensure compressive strength, the insulation material obtained 6 deteriorates the thermal conductivity. Resin D with a hydroxyl value of 600 Misaki KOH/, 9 or more
In this case, the flyability was poor and the powder was pulverized in the heat insulating body under reduced pressure, so that the heat insulating body 6 could not be formed.

These phenomena are thought to be influenced by the compatibility of raw materials and the process leading to resin curing, but the details of this process have not yet been elucidated.

By using the hard urethane foam 4 which is foamed and has a fine cell skeleton as the core material of the heat insulating body 6 as described above, the thermal conductivity of the gas in the heat insulating body θ is as follows.

Compared to those with a larger bubble skeleton diameter, it can reduce pressure to the same level even at high pressures, and is easy to handle industrially.
．． Demonstrates excellent heat insulation performance at 0.01 mm Hg. As a result, the evacuation time is short, making it easier to mass-produce, and the evacuation device is also simple, allowing pressure to be obtained, which greatly contributes to productivity. It has no problems, has excellent dimensional stability, and has good workability in secondary processing. It should be noted that if the bubble skeleton diameter is made finer, the exhaust resistance increases and the exhaust time required to reduce the pressure to a predetermined pressure becomes longer.
There is no effect in the 1111111 Hg region, and an effect appears in the 0,001 M Hg region where the molecular flow region dominates. Therefore, the heat insulator used in the present invention has a thickness of 0.1 to 0.01 m.
m) (Since sufficient heat insulating performance can be exhibited at a pressure of g, there is no problem with productivity even if the cell skeleton diameter is made finer.

Effects of the Invention As is clear from the above description, the present invention provides the following effects.

Hydroxyl value 400-800 mm HCJ benzylic ether type phenol resin and organic polyisocyanate,
A hard phenolic urethane foam with an open cell structure obtained using a catalyst, a foam stabilizer, a blowing agent, and a cell communication agent is
It has an extremely fine cell skeleton. Therefore, by covering the container with this urethane foam metal-plastinox laminate film and reducing the pressure inside, the temperature will be 0°01 to 0.0°, which is easy to handle industrially. Even at a pressure of 1 mmHg, the heat conduction of the gas is sufficiently reduced and it exhibits excellent heat insulation properties, so it can be mass-produced in a short time and with simple exhaust equipment, contributing to a significant improvement in productivity. In addition, the hard phenol urethane foam that serves as the core material has the advantage of having excellent dimensional stability without problems with foam yield or flyability, and good workability in secondary processing and the like.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a hard phenolic urethane foam according to an embodiment of the present invention, FIG. 2 is a sectional view of the same heat insulating body, and FIG. 3 is a sectional view of a conventional heat insulating structure. 4...Hard phenolic urethane foam, 5.
...Container, 6...Insulator. Name of agent: Patent attorney Shigetaka Awano and one other gP
w phenolfredasof1-mu5-100 butybean6-・m sad oo

Claims (1)

[Claims] A hard phenolic urethane foam with an open cell structure obtained using a benzylic ether type phenolic resin with a hydroxyl value of 400 to 600 mgKOH/g, an organic polyisocyanate, a catalyst, a foam stabilizer, a blowing agent, and a cell communication agent is made into a metal-plastic material. An insulator that is covered with a container made of laminate film and sealed by reducing the pressure inside.