Process for the preparation of rigid foams comprising the step of reacting an organic polyisocyanate with an isocyanate-reactive material in the presence of a blowing promotor being an isocyanate-reactive cyclic compound of formula:
wherein
Y is O or NR¹ wherein each R¹ independently is a lower alkyl radical of C₁-C₆ or a lower alkyl radical substituted with an isocyanate-reactive group;
each R independently is hydrogen, a lower alkyl radical of C₁-C₆ or (CH₂)m-X wherein X is an isocyanate-reactive group which is OH or NH₂ and m is 0, 1 or 2; and
n is 1 or 2;
with the proviso that at least one of R¹ or R is or comprises an isocyanate-reactive group;
and in the presence of an inert insoluble organic liquid which is present as the dispersed phase of an emulsion or a microemulsion and in the presence of a metal salt catalyst, wherein the isocyanate-reactive material comprises a polyol or polyol mixture of average nominal functionality between 2 and 3 and number average equivalent molecular weight between 31 and 750.
制备硬质泡沫塑料的工艺,包括以下步骤:在发泡
促进剂(一种
异氰酸酯反应型环状化合物)存在下,使有机多
异氰酸酯与
异氰酸酯反应型材料发生反应:
其中
Y 是 O 或 NR¹,其中每个 R¹ 独立地是 C₁-C₆ 的低级烷基或被
异氰酸酯反应基团取代的低级烷基;
每个 R 独立地是氢、C₁-C₆ 的低级烷基或 (CH₂)m-X,其中 X 是 OH 或 NH₂ 的
异氰酸酯反应基团,m 是 0、1 或 2;以及
n 为 1 或 2;
但 R¹ 或 R 中至少有一个是或包含一个
异氰酸酯反应基团;
在惰性不溶性有机液体(作为乳液或微乳液的分散相)和
金属盐催化剂的存在下, 其中
异氰酸酯反应物包括平均公称官能度在 2 和 3 之间、平均当量分子量在 31 和 750 之间的多元醇或多元醇混合物。