A process is provided for producing a polyurethane foam having a high-density skin layer by reacting a polyol with a polyisocyanate in a short time. The reaction is allowed to proceed in the presence of a blowing agent, a catalyst, and optionally an additive, the blowing agent being composed only of water, and the catalyst being an amine represented by the general formula (I) below and/or an organic acid salt thereof:
 where R₁, R₂, R₃, and R₄ represent independently an alkyl group of 1 to 12 carbons, or R₁ and R₂, and/or R₃ and R₄ may be linked to form a (cycloalkyl, or heterocyclic) ring together with the adjacent nitrogen atom; and R₅ is hydrogen, an alkyl group of 1 to 12 carbons, a phenyl group, or a cycloalkyl group. This process does not use any halogenated hydrocarbon which causes ozone layer destruction.
                            本发明提供了一种通过使多元醇与多
异氰酸酯在短时间内发生反应来生产具有高密度表 皮层的聚
氨酯泡沫塑料的工艺。反应在发泡剂、催化剂和可选添加剂的存在下进行,其中发泡剂仅由
水组成,催化剂为以下通式(I)表示的胺和/或其有机酸盐:
 其中 R₁、R₂、R₃ 和 R₄ 独立地代表 1 至 12 个碳原子的烷基,或 R₁ 和 R₂,和/或 R₃ 和 R₄ 可与相邻的氮原子连接形成一个(环烷基或杂环)环;R₅ 是氢、1 至 12 个碳原子的烷基、苯基或环烷基。该工艺不使用任何会破坏
臭氧层的卤代烃。