申请人:THE DOW CHEMICAL COMPANY
公开号:EP0075130A2
公开(公告)日:1983-03-30
The use of certain prepolymers of 4,4'-methyienebis-(phenyl isocyanate), in place of the latter diisocyanate itself in the preparation of polyurethane-polyureas using aromatic diamine extenders, has a number of advantages par- ticuiariy when the compositions are prepared by reaction injection molding techniques using two streams of reactants. The principal advantages are (i) a useful increase in gel time and (ii) a ratio of amounts of the two reactant streams which more nearly approaches 1:1.
This latter factor not only improves the efficiency of mixing of the components in the mixing head but, together with the longer gel time, significantly increases the output of mixed reactants per unit of time. The prepolymers of 4,4'- methyienebis(phenyi isocyanate) employed to achieve the above results are those derived from polyoxy-ethylene polyoxypropylene polyether diols and triols (MW = 1000-10.000), polytetramethylene glycols (MW = 600-5.000) and polyester diols and triols (MW = 500-8.000).
在使用芳香族二胺扩展剂制备聚氨酯聚脲时,使用 4,4'-亚甲基双(苯基异氰酸酯)的某些预聚物来代替后者的二异氰酸酯本身,具有许多优点,尤其是在使用两股反应物流通过反应注射成型技术制备组合物时。主要优点有:(i) 有效延长凝胶时间;(ii) 两股反应物的比例更接近 1:1。
后一个因素不仅提高了混合头中各组分的混合效率,而且与更长的凝胶时间一起,显著提高了单位时间内混合反应物的产量。为达到上述效果而使用的 4,4'-亚甲基双(苯基异氰酸酯)预聚物是从聚氧乙烯聚氧丙烯聚醚二醇和三醇(分子量=1000-10.000)、聚四甲基二醇(分子量=600-5.000)和聚酯二醇和三醇(分子量=500-8.000)中提取的。