초록 ▼

The heat insulator of this invention comprises a thermoformed open cell rigid polyurethane foam core enclosed in a gas barrier material and evacuated. The method of this invention comprises heating an open cell rigid polyurethane foam at a temperature not lower than the temperature at which its stor

The heat insulator of this invention comprises a thermoformed open cell rigid polyurethane foam core enclosed in a gas barrier material and evacuated. The method of this invention comprises heating an open cell rigid polyurethane foam at a temperature not lower than the temperature at which its storage modulus of elasticity begins to decrease and enclosing the thus-thermoformed polyurethane foam in a gas barrier material and evacuating the interior of the enclosure. The heat insulator of the invention is highly heat-insulating and can be snugly applied to irregular surfaces.

대표청구항 ▼

A method for producing a heat insulating material which comprises thermoforming an open cell rigid polyurethane foam obtained by reacting a polyol mixture and an organic polyisocyanate, enclosing the thermoformed foam in a gas barrier material, and evacuating the interior of the enclosure, said poly

A method for producing a heat insulating material which comprises thermoforming an open cell rigid polyurethane foam obtained by reacting a polyol mixture and an organic polyisocyanate, enclosing the thermoformed foam in a gas barrier material, and evacuating the interior of the enclosure, said polyol mixture having a hydroxyl value of 160-500 mgKOH/g, and comprising: a) 10-60% by weight of a polyoxyalkylene polyol having an average functionality of 2-3.5, a hydroxyl value of 26-90 mgKOH/g, an oxyethylene unit content of not more than 5% by weight based on whole polyoxyalkylene polyol and a primary hydroxyl group content of not more than 15% based on the total of hydroxyl groups of the whole polyoxyalkylene polyol; (b) 20-80% by weight of a polyoxyalkylene polyol having an average functionality of 3-6, a hydroxyl value of 150-600 mgKOH/g, an oxyethylene unit content of not more than 5% by weight based on whole polyoxyalkylene polyol and a primary hydroxyl group content of not more than 15% based on the total of hydroxyl groups of the whole polyoxyalkylene polyol; and (c) 0-25% by weight of a polyoxyalkylene polyol having an average functionality of 2-3 and a hydroxyl value of over 600 mgKOH/g to 840 mgKOH/g, said organic polyisocyanate being a polymethylenepolyphenylene polyisocyanate, its prepolymer or a mixture thereof and wherein said thermoforming step produces at least a portion of the cells of the foam to have an anisotropic cell dimension.