Hitachi, Ltd.

Kazuyoshi Kuroishi

Reishi Naka

Isao Kobayashi

Kousuke Tanaka

Katuhiko Gotoo

A rigid polyurethane foam obtained by foaming a special polyol component and an isocyanate component in the presence of a blowing agent comprising water and at least one member selected from the group consisting of 1,1-dichloro-2,2,2-trifluoroethane and 2,2-dichloro-2-monofluoroethane possesses balanced excellent properties, has no surface void, and shows only slight expansion after molding. Therefore, it can be effectively used as a heat insulator, in particular, a heat insulator for refrigerators.

Rigid polyurethane foam and process for producing the same

A rigid polyurethane foam obtained by foaming a special polyol component and an isocyanate component using only water as a blowing agent has balanced excellent properties including a remarkably low density and a low thermal conductivity and is suitable for use as a heat insulator, particularly in a refrigerator.

Rigid polyurethane foam and heat insulator obtained therefrom

A rigid polyurethane foam produced by reacting a special polyol component with an isocyanate component in the presence of a blowing agent containing water in an amount of 2 to 3.5% by weight per 100% by weight of the polyol component is excellent in fluidity with balanced excellent properties.

Rigid polyurethane foam, process for producing the same, and heat

Rigid polyurethane foams produced by reacting a polyol component having a special composition with an isocyanate component in the presence of a blowing agent, a reaction catalyst and a foam stabilizer with a mold release time of as short as 5.5 minutes or less, have remarkably low thermal conductivity of 12.5.times.10.sup.-3 Kcal/m.hr..degree.C. or less and a low density and are suitable as heat insulating materials for refrigerators and the like.

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Tochigi, Japan

Kazuyoshi Kuroishi