| 摘要 |
PURPOSE: A method for preparing a semihard polyurethane resin composition as a construction material for an imaginary set is provided, to obtain a construction material having such physical properties (specific gravity, strength) for an imaginary set to substitute effectively a real construction material. CONSTITUTION: The method comprises the steps of making a mold having the shape of a composition; mixing methyl isocyanate and a polyol mixture in the ratio of 1:1 by equivalence at a room temperature; pouring the obtained mixture into the mold; and foaming it and demolding the foamed one. Preferably the methyl isocyanate is a unprocessed methyl isocyanate or a liquefaction modified methyl isocyanate; and the polyol mixture comprises a polyol containing three hydroxyl groups and having a molecular weight of 5,000, a polyol containing three hydroxyl groups and having a molecular weight of 6,000, a polyol containing four hydroxyl groups and having a molecular weight of 300, a polyol containing two hydroxyl groups and having a molecular weight of 98, and a tertiary amine catalyst.
|
