| 摘要 |
The present invention therefore relates to a process for the preparation of aqueous solutions or dispersions of polyurethane-polyureas by the reaction in the aqueous phase of prepolymers which contain chemically built-in hydrophilic groups and/or external emulsifiers which are not bound chemically as well as at least two free isocyanate groups with organic compounds containing at least two primary and/or secondary amino groups, characterized in that the isocyanate prepolymer which has been hydrophilically modified and/or contains an external emulsifier is mixed, in the absence of water, with compounds containing at the most one free primary or secondary amino group and at least one blocked group which releases a free primary or secondary amino group in the presence of water and a total of at least two at least partially blocked primary and/or secondary amino groups, and the mixture is subsequently mixed with water. The invention also relates to the dispersions or solutions obtained by this process and to their use for coating flexible and rigid substrates. |
