Process for the production of stabilized polyisocyanates, the polyisocyanates so-stabilized and their use in the production of polyurethanes

A process for the production of solid polyisocyanates stabilized by a polymer coating and showing retarded reactivity comprising reacting

• (1) one or more solid polyisocyanates in particulate form, said polyisocyanates having melting points above 30.degree. C., and
• (2) from 0.1 to 25 equivalent percent of amine per isocyanate equivalent of a compound having a molecular weight of from 32 to 6000, said compound being selected from the group consisting of
• (a) organic di- or higher functional compounds containing 2 or more aliphatically-bound primary and/or secondary amino groups,
• (b) organic compounds containing one or more terminal --CO--NH--NH.sub.2 groups,
• (c) hydrazines, and
• (d) mixtures thereof
• said reaction being conducted at a temperature below the melting temperature of said solid polyisocyanate, and being conducted in the presence of
• (3) a liquid medium selected from the group consisting of
• (a) organic compounds containing 2 or more aromatically-bound amino groups and having molecular weights of from 108 to 6000,
• (b) organic compounds containing 2 or more aliphatically-bound amino groups and having molecular weights of from 400 to 6000,
• (c) plasticizers,
• (d) water, and
• (e) mixtures thereof to form a suspension of polyadduct-coated, stabilized polyisocyanate in the liquid medium.

A process for the production of solid polyisocyanates stabilized by a polymer coating and showing retarded reactivity comprising

• (A) reacting:
• (1) one or more solid polyisocyanates in particulate form, said polyisocyanates having melting points above 30.degree. C., and
• (2) from 0.1 to 25 equivalent percent of amine per isocyanate equivalent of a compound having a molecular weight of from 32 to 6000, said compound being selected from the group consisting of
• (a) organic di- or higher functional compounds containing 2 or more aliphatically-bound primary and/or secondary amino groups,
• (b) organic compounds containing one or more terminal --CO--NH--NH.sub.2 groups,
• (c) hydrazines, and
• (d) mixtures thereof,
• said reaction being conducted at a temperature below the melting temperature of said solid polyisocyanate, and being conducted in the presence of an organic compound containing one or more hydroxyl groups and having molecular weights of from 400 to 6000 to form a suspension of polyadduct-coated, stabilized polyisocyanate,
• (B) adding to the suspension one or more organic compounds containing 2 or more aromatically-bound amino groups and having molecular weights of from 108 to 399.