JPS5834500B2 - Method of manufacturing urethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyurethane foam suitable as a heat insulating material.

Various plastic foams made of closed cells, including rigid urethane foam, are used as heat and cold insulation materials.

In particular, rigid urethane foams are often used as insulation materials for refrigerators due to their dimensional stability and shape retention.

By the way, this type of plastic foam is manufactured by the froth method, in which a so-called foaming stock solution containing a foaming agent is discharged from a nozzle, or dichlorodifluoromethane is added and discharged.

On the other hand, in response to the demand for energy conservation, we are improving the insulation performance of plastic foam, which is often used as an insulation material.
Reduction of raw materials is attracting attention.

The raw material savings for this insulation material are due to the low specific gravity of the foam (
(increase in foaming ratio).

However, lowering the specific gravity generally leads to a decrease in heat insulation properties and a decrease in dimensional stability at low temperatures.

It is also known that plastic foam has a minimal bulk specific gravity that determines its heat insulating properties (thermal conductivity), and rigid urethane foam exhibits a minimal thermal conductivity at a bulk density of 30Kp/□8. It has also been confirmed that when the density is less than 30/2/TrL3, the increase in radiant heat transfer influences the increase in thermal conductivity of the foam.

In order to solve the two demands of improving low-temperature dimensional stability and reducing the amount of radiant heat transfer, the inventors of the present invention have conducted various studies, and as a result, have added and blended fibrous hydrated iron oxide into a hard urethane foaming stock solution. It has been found that when foamed, a rigid polyurethane foam with low thermal conductivity and good low-temperature dimensional stability can be easily obtained.

The present invention is based on the above findings and aims to provide a method for producing polyurethane foam suitable as a heat insulating material for refrigerators.

That is, the present invention uses a foaming stock solution generally used in the production of polyurethane foam, for example, a hydroxyl value of 200 to 30.
0.0 per 100 parts by weight of polyol, 180
About 120 parts by weight of hydrated iron oxide (F e o
o H) is used as a foaming stock solution.

In the present invention, the hydrated iron oxide, which is a component of the foaming stock solution, generally has an average diameter of about 100λ or more and a length of about 10
A fibrous material with a size of about 0.00 or less is selected.

However, as the hydrated iron oxide, α-Fe00H, β
-F e OOH, 7'-F e OOH, etc., β-Fe00H is particularly preferred, αFe00H, γ-F
In the case of e00H, it is preferable to select the amount added appropriately.

In addition, the composition ratio of these hydrated iron oxides is approximately 1 to 20 parts by weight in the case of βFe0OH per 100 parts by weight of the foaming stock solution.
In the case of α-FeOOH and 7'-FeOOH, it is preferable to select approximately 5 to 15 parts by weight.

Next, examples of the present invention will be described.

Example 1 Polyoxypropylene polyol with a hydroxyl value of 450, crude tolylene diisocyanate, silicone foam stabilizer TFA42
00 (trade name, Toshiba Silicon Corporation), triethylenediamine as a catalyst, trichlorofluoromethane (blowing agent)
, water, and hydrated iron oxide β-Fe00H were blended in the composition ratio (parts by weight) shown in Table 1 to prepare a foamable stock solution.

Polyurethane foam was obtained by foaming each of the foamable stock solutions described above.

Regarding the foam obtained in this way, the bulk density is /, rrL3
The results of measuring the thermal conductivity λ·Kcal/m, h, and 'C (measurement temperature 20° C.) are also shown in Table I.

Example 2 Polyoxypropylene polyol 100 with a hydroxyl value of 450
Parts by weight: 116 parts by weight of crude tolylene diisoanate, 1.5 parts by weight of silicone foam stabilizer, 2. parts by weight of triethylenediamine.
0 parts by weight, trichlorofluoromethane, 1.0 parts by weight of water, and 10 parts by weight of hydrated iron oxide (β-7FeoOH). Different urethane foams were obtained.

The thermal conductivity of each of the foams thus obtained was measured, and the relationship between bulk density and thermal conductivity was determined, and the results were as shown by curve A in FIG.

For comparison, the bulk density of a foam obtained under the same conditions except that it does not contain a hydrous iron oxide component in a foaming stock solution with the above composition is shown below. /m3 and thermal conductivity λK c a l:
When the relationship between /m, h2, and °C was determined, it was as shown by curve a in FIG.

In addition, in the foamable stock solution according to the above example, the amount of hydrated iron oxide added was changed, and the foaming conditions were selected to be constant, and the bulk density was 25KL.
? /m8 rigid polyurethane foam was obtained.

The relationship between the content (composition ratio) of hydrated iron oxide and the thermal conductivity λ·Kcal/m, h, and 'C of the thus obtained foam was determined as shown in FIG. 2.

On the other hand, polyurethane foams having different bulk densities were obtained using foaming stock solutions with different amounts of hydrated iron oxide added.

The dimensional accuracy (dimensional change rate %) and bulk density Kli'/m at -30°C for the thus obtained foams, respectively.
When the relationship with 3 was determined, it was as shown in Fig. 3.

In Fig. 3, curve B is for the case where the composition ratio of hydrated iron oxide is 2 parts by weight, curve C is for the case when the composition ratio of hydrated iron oxide is 4 parts by weight, and curved line is for the case when the composition ratio of hydrated iron oxide is 5 parts by weight. The curves show the case where hydrated iron oxide is not included (comparative example).

As is clear from the above examples, according to the method of the present invention, a polyurethane foam having excellent properties such as low thermal conductivity and low-temperature dimensional stability can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing the relationship between bulk density and thermal conductivity for polyurethane foams produced by the method of the present invention and a method other than the present invention, and FIG. 2 is a curve diagram showing the relationship between the composition ratio of hydrated iron oxide and FIG. 3 is a curve diagram showing the relationship between the thermal conductivity of the obtained polyurethane foam, and FIG. 3 is a curve diagram comparing the relationship between bulk density and dimensional stability of polyurethane foams produced by the method of the present invention.

Claims (1)

[Claims] 1 A urethane foam characterized by adding and distributing hydrated iron oxide (FeooH) to a foamable stock solution containing a catalyst, a blowing agent, and a foam stabilizer, which is mainly composed of polyols and incyanates with a hydroxyl value of 200 to 800, and is foamed. Production method.