JPH01101321A - Heat insulator - 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 Technical Field The present invention relates to a heat insulator used in refrigerators and the like.

<Prior art> In recent years, the need for refrigerators has been moving toward larger capacity, but there are limits to the installation space due to housing conditions, etc., and the ratio of internal volume to external volume of refrigerators is high. As a result, making the walls of the insulation body thinner has become an important issue.

Generally, rigid polyurethane foam is used for the insulation of refrigerators, and its raw material formulation is sucrose-based, aromatic diamine-based polyether polyol, amine catalyst, silicone-based foam stabilizer, and foaming agent R. -11 with an organic isocyanate to increase the degree of polymerization.

Recently, formulations in which part of the polyether polyol is replaced with polyester polyol or pensilicate phenol have been considered in order to improve the heat insulation performance.

Anchor〈Problems to be solved〉 ・In such a heat insulator, the polyol does not have sufficient y-reactive activity, so the cells do not become fine in the early stage of the reaction with the organic isocyanate, and the thermal conductivity of the heat insulator does not reach a sufficient level. The drawback was that it did not become smaller.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a heat insulator that provides excellent heat insulation performance.

Means for Solving the Problems〉 〛The present invention increases the reaction activity of the polyol by adding 30% by weight or less of polyester polyol synthesized using an organometallic catalyst to the polyol component, thereby creating a heat insulating material with low thermal conductivity. get.

<Function> As described above, in the present invention, by adding polyester polyol/L/ synthesized using an organometallic catalyst to the polyol component, the isocyanate group at the rose position of TDI in the organic isocyanate and the polyester polyol are combined. Because the reaction occurs quickly, the cells become finer in the early stage of the reaction, making it possible to obtain a heat insulator with sufficiently low thermal conductivity.

<Example> An example of the present invention will be described below based on figures and tables.

In the table, Polyol A is an aromatic diamine-based, sucrose-based polyether polyol with a hydroxyl value of 45' Omg KOH/g, and Polyol-1vB is a phthalate-based polyether polyol synthesized by a conventional method with a hydroxyl value of 400 mg KOH/g.
The polyester polyol of g, POLY-PC, is a phthalate ester polyol synthesized using an organometallic catalyst and has a hydroxyl value of 4.
00mgKOH/g polyester polyol.

The foam stabilizer is 1.5 parts of a silicone surfactant, the blowing agent is Freon R-11, and the catalyst is an amine-based or organometallic catalyst, and the amounts of the blowing agent and catalyst are set so that the density responsiveness of the insulation material is the same. Therefore, υ was adjusted according to the raw material formulation. Organic isocyanate is crude TDI TDI prepolymer mixture (
i135 per amine) and crude MDI (amine equivalent 135)
were mixed in a weight ratio of 70:30. Panel foaming was carried out using various combinations of these raw materials, and some of them were used as examples to represent blacks 1 to 5.

The thermal conductivity of the obtained rigid polyurethane foam was measured at an average temperature of 32° C. using a Showa Denko thermal conductivity meter QTM.

As is clear from the table, polyol B/L/(i.e., a formulation containing a polyester polyol synthesized using an organometallic catalyst) is polyol B, i.e., a polyester polyol synthesized by a conventional method without using a catalyst. A heat insulator with a lower thermal conductivity was obtained compared to the added recipe point 2 and 3.

This is considered to be because the reaction activity of polyol C is high, and the reaction with the organic isocyanate occurs quickly, resulting in finer cells in the initial stage of the reaction.

The figure shows the results obtained by various foaming tests on the relationship between linear number #1 (shrinkage at room temperature after demolding) and thermal conductivity by varying the amount of polyol C added to the polyol component. The primary shrinkage rate was measured after 24 hours at room temperature, and the thermal conductivity was measured at an average temperature of 32°C. As is clear from this figure, the shrinkage rate increases as the amount of polyol/L/co added increases, but the thermal conductivity tends to remain almost constant even when 15 parts or more is added to the polyol component. Recognize. It is thought that this is because as the amount of polyol C added increases, the bond between polyol-A/C and crude MDI increases, resulting in a decrease in mechanical strength, a decrease in the strength of the heat insulator, and an increase in primary shrinkage. On the other hand, the thermal conductivity is greatly influenced by the state of the cell at the initial stage of the reaction between the organic isocyanate and the polyol, that is, in the examples of the present invention, it is influenced by the reaction between polyol C and the isocyanate group at the distal position of the crude TDI. Therefore, the hydroxyl group of polyol C and the crude TD
It is considered that even if the equivalent ratio of the isocyanate group at the I-position becomes 1 or more, the thermal conductivity does not change significantly.

Note that the present invention is not limited to the above embodiments,
By adjusting the catalyst, foam stabilizer, polyol component, etc., it is also possible to obtain a heat insulator with better heat insulation performance.

<Effects> The present invention provides a rigid polyurethane foam heat insulating material obtained using a polyol, an organic isocyanate, a catalyst, a foam stabilizer, and a foaming agent as described above, in which a polyester polyol synthesized using an organometallic catalyst as the polyol component is used. Since this relates to a heat insulating body characterized by containing 30 weight Φ or less of polyester polyol (polyol It is a figure showing the relationship between the content of C), the primary shrinkage rate, and the thermal conductivity.

Claims (1)

[Claims] 1. In a rigid polyurethane foam insulation obtained using a polyol, an organic isocyanate, a catalyst, a foam stabilizer, and a foaming agent, 30% by weight of a polyester polyol synthesized using an organometallic catalyst is added to the above polyol component.
A heat insulator characterized by containing the following: