JPS63116082A - Manufacture of heat insulator - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a heat insulator for use in refrigerators, refrigerators, refrigerators, etc.

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 No. 70, a proposal has been made to use a hard urethane foam having open cells as a core material. To explain this Japanese Patent Application Laid-open No. 67-133870 with reference to FIG. 3, %1 in the figure is a heat insulating structure in which a hard urethane foam 2 having open cells is covered with a container 3 made of an airtight thin film.
The interior is depressurized to 0.001m5+Hg and sealed.

The hard urethane foam 2 has a cell skeleton diameter of 300 to 100.
The feature is that a commercially available general material with a diameter of about 0 μm is vacuum degassed under high temperature and high humidity to break the cell membrane 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 hard urethane foam 2 is 300 to 100μm, the thermal conductivity of the gas must be lowered to a pressure of 0.001 rrmHq or less. is not small enough, 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 the longer the distance between the walls, the more the same Lower pressures are required to obtain gas thermal conductivity. The general formula is represented by the following formula (1).

kg = AρVCr (L f d/(L f +d
) ) −・−・−・−・−(1) 2kq: Thermal conductivity of gas A: Constant ρ: Density Cky/m” ]V: Average molecular velocity (m/s) Lf: Mean free path C, ) Cr2 specific heat kc a l ACq'' Cod: distance between walls [m] Therefore, in the conventional example, the bubble skeleton diameter is 30
Since the thickness is 0 to 1000 μm, a pressure of 10 mmHg or less, which is difficult to handle in an industrial manner, is required f), and there are problems such as requiring large-scale equipment and long evacuation time in mass production. Furthermore, in the pressure range below 10-3 mmHg, it is easily affected by the amount of gas released by the material, and in the case of this composition of organisms that tend to contain low molecular weight heptamer components, there is a problem that the evacuation time is particularly long, and mass production It was inefficient.

In view of the above-mentioned problems, the present invention aims to shorten the evacuation time and enable mass production by obtaining excellent heat insulation performance in a low vacuum range that is easy to handle industrially.

Means for Solving the Problems The present invention aims to solve the above problems by using an organic polyinsyanate, a polyol, a catalyst, and a foam stabilizer.

When manufacturing a rigid urethane foam with an open cell structure using a blowing agent and a cell communication agent, foaming is performed at a reaction rate within 20 seconds for gelation time (time from mixing raw materials to gelation of the foam). The hard urethane foam with open cell structure obtained in this process is used as the core material of the vacuum insulation body.

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-plasticinox laminate film, and when the inside is depressurized, the o.
Excellent heat insulation performance was obtained even at an industrially easy-to-handle pressure of about 0.1 mmH (J), and mass production efficiency was greatly improved by shortening the exhaust time.

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

In the figure, 4 is a hard urethane foam made by foaming and curing in a urethane high-pressure foaming machine using the raw materials shown in the table below.
After aging at room temperature, it is cut into a predetermined size.

In the table, polyol A is obtained by addition polymerizing propylene oxide (hereinafter referred to as PO) using tolylene diamine as an initiator.
7 polyether polyol.

The foam stabilizer is silicone surfactant F- manufactured by Shin-Etsu Chemical Co., Ltd.
318, the blowing agent is Freon R-11 manufactured by Showa Denko Co., Ltd.
Catalyst A is a 20% solution of potassium acetate and rum.

Catalyst B was dibutyltin dilaurate, and the cell communication agent was calcium stearate manufactured by NOF Corporation. Organic polyisocyanate A is a polyisocyanate with an amine equivalent of 150 obtained by reacting toluylene diisocyanate with trimethylpropane and diethylene glycol. Foaming was carried out using various combinations of these raw materials, and some of them were used as examples for protections 1 to 3. LA is shown as a comparative example.

The gelation time is also shown in the table. The density, open cell ratio, and cell skeleton diameter of the obtained hard urethane foam 4 are also shown in the table. Thereafter, the obtained rigid urethane foam 4 was heated at 120°C for about 2 hours to evaporate the adsorbed moisture, and then covered with a container 6 consisting of a laminate structure of an aluminum-deposited polyester film and a polyethylene film, and a metal-plastic laminate film. , inside 0.001,0,01, o++
The pressure was reduced to 1.0.6,1*OmmHg, and the heat insulator 6 was obtained. The exhaust time at this time is from Example 1 to F.
;, 3 are 30 minutes, 6 minutes, 2 minutes, 1 minute, and 30 seconds, respectively, and Comparative Example 1hA is 26 minutes, 6 minutes, 2 minutes, and 1 minute, respectively.

It was 30 seconds. The thermal conductivity of the obtained heat insulator e immediately after sealing is also shown in the table. The thermal conductivity was measured using K-Matic manufactured by Shinku Riko Co., Ltd. at an average temperature of 24°C.

As is clear from the table, the heat insulating body 6 of the present invention has a ta of 0.1 to 0.01 ta, which allows for finer bubbles and is easier to handle industrially.
It was found that it exhibits excellent heat insulation performance even at a pressure of nHq. This is because when the gelation time is 20 seconds or less, the viscosity increases significantly due to rapid resin curing, suppressing the coalescence of bubbles and making it possible to make the bubbles finer. In other words, by using the hard urethane foam 4 having this fine cell skeleton as the core material of the heat insulating body 6, the gas heat conduction in the heat insulating body e can be made to the same degree even at high pressure as compared to one with a larger cell skeleton. 0.0 that can be reduced and is easy to handle industrially.
Demonstrates excellent heat insulation performance at 1 to 0.01 mmHg.

As a result, since the evacuation time is short, mass production is easy, and pressure can be obtained with a simple evacuation device, which greatly contributes to productivity.

Furthermore, if the bubble skeleton is made finer, the evacuation resistance increases and the evacuation time required to reduce the pressure to a predetermined pressure is thought to become longer, but in the 0.01 mmHg region, there is no effect and the molecular flow region dominates. 0, 001 tyrH
The influence appears at q. Therefore, there is no problem with productivity by using a pressure of 0.1 to 0.01 mmHg, which provides sufficient heat insulation performance even when miniaturized.

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

Organic polyinsyanate, polyol, catalyst, foam stabilizer 2
A hard urethane foam with an open cell structure is produced using a blowing agent and a cell communication agent, and the gelation time is 2.
Since the rigid urethane foam with the open cell structure obtained in this way has an extremely fine cell skeleton, it is covered with a container made of a metal-plastic laminate film, and the inside is covered with a container made of a metal-plastic laminate film. When the pressure is reduced, it becomes 0.01-0.1 mmHg, which is easy to handle industrially.
The heat conduction of the gas is sufficiently reduced even at a pressure of 100 mL, and excellent heat insulation properties are obtained, making it possible to mass-produce in a short time and with simple exhaust equipment, contributing to a significant improvement in productivity.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a rigid 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 urethane foam, 6...
Container, 6...Insulator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Edit: Really, I'm talented.

Claims (1)

[Claims] Organic polyisocyanates, polyols, catalysts, foam stabilizers,
When producing rigid urethane foam with an open cell structure using a blowing agent and a cell communication agent, foaming is performed at a reaction rate within 20 seconds for gelation time (time from mixing raw materials to gelation of the foam). A method for producing a heat insulator, in which the rigid urethane foam obtained is covered with a container made of a metal-plastic laminate film, and the inside of the container is sealed under reduced pressure.