| 摘要 |
<p>PURPOSE: To prevent the discoloration of a PVC joint by preparing the foam by reacting an organic polyisocyanate with a specific polymeric polyol and a crosslinking agent or a chain extender in the presence of water and an alkali metal or alkaline earth metal salt of a specific organic acid. CONSTITUTION: In a composite article of a semi-rigid polyurethane foam in contact with a layer of sheet of polymeric material, the foam is prepared by reacting an organic polyisocyanate with a polymeric polyol having a hydroxyl number in the range from 20 to 80 and a crosslinking agent or chain extender having a hydroxyl number of at least 250 in the presence of water and a catalytically effective amount of an alkali metal or alkaline earth metal salt of an acid of the formula; R-A-COOH (R represents R'OCO-, R'COO- or R'O-, R' representes a substituted hydrocarbon or heterocyclic group, and A represents a substituted 1-3C chain). The foam prepared by the method mentioned in the above, is free from the deterioration of PVC in a joint part even when the foam is kept into contact with PVC to form the composite article.</p> |
