Process for the production of new polyisocyanate compositions and their use for the production of plastics by the isocyanate polyaddition process

A polyisocyanate preparation containing urethane groups and having an isocyanate content of about 18 to 28% by weight which is prepared by a process which comprises reacting

• (a) an organic polyisocyanate having aromatically bound isocyanate groups and an isocyanate content of about 30 to 50% by weight or a mixture comprising said organic polyisocyanate, said mixture having an isocyanate content of about 30 to 50% by weight with
• (b) an organic polyhydroxyl compound comprising
• (b1) a polyhydroxypolyacrylate having an average molecular weight, as determined by vapor pressure osmometry, of 232 to about 100,000, optionally containing urethane or ester groups in side chains and containing on statistical average at least one alcoholic hydroxyl group per molecule, said polyhydroxypolyacrylate being prepared by polymerizing an ester of .alpha., .beta.-ethylenically unsaturated acid containing a hydroxyalkyl group or by polymerizing such an ester with another olefinically unsaturated monomer and
• (b2) up to about 250% by weight, based on b1), of at least one polyhydroxyl compound other than b1) having a molecular weight of 62 to about 12,000, wherein the equivalent ratio of isocyanate groups to hydroxyl groups is at least 1.8:1.

A process for the preparation of a polyurethane or a polyurethane polyurea in the form of an optionally cellular molded article having a compact surface, which comprises reacting in a closed mold

• (I) a polyisocyanate preparation containing urethane groups and having an isocyanate content of about 0.5 to 45% by weight which is prepared by a process which comprises reacting
• (a) an organic polyisocyanate having an isocyanate content of about 30 to 50% by weight or a mixture comprising said organic polyisocyanate, said mixture having an isocyanate content of about 30 to 50% by weight with
• (b) an organic polyhydroxyl component comprising
• (b1) a polyhydroxypolyacrylate having an average molecular weight, as determined by vapor pressure osmometry of 232 to about 100,000, optionally containing urethane or ester groups in side chains and containing on statistical average at least one alcoholic hydroxyl group per molecule and
• (b2) up to about 250% by weight, based on b1), of at least one polyhydroxyl compound other than b1) having a molecular weight of 62 to about 12,000, wherein the equivalent ratio of isocyanate groups to hydroxyl groups is at least about 1.8:1, and
• (II) an isocyanate-reactive component comprising at least one compound having a molecular weight of 400 to about 12,000 which contains at least two isocyanate-reactive groups and, optionally, at least one compound having a molecular weight of 32 to 399 which contains at least two isocyanate reactive groups.

A process for the preparation of a polyurethane or a polyurethane polyurea in the form of an optionally cellular molded article having a compact surface, which comprises reacting in a closed mold

• (I) a polyisocyanate preparation containing urethane groups and having an isocyanate content of about 18 to 28% by weight which is prepared by a process which comprises reacting
• (a) an organic polyisocyanate having aromatically bound isocyanate groups and an isocyanate content of about 30 to 50% by weight or a mixture comprising said organic polyisocyanate, said mixture having an isocyanate content of about 30 to 50% by weight with
• (b) an organic polyhydroxyl component comprising
• (b1) a polyhydroxypolyacrylate having an average molecular weight, as determined by vapor pressure osmometry of 232 to about 100,000, optionally containing urethane or ester groups in side chains and containing on statistical average at least one alcoholic hydroxyl group per molecule, said polyhydroxy polyacrylate being prepared by polymerizing an ester of .alpha., .beta.-ethylenically unsaturated acid containing a hydroxyalkyl group or copolymerizing such an ester with an olefinically unsaturated monomer and
• (b2) up to about 250% by weight based on b1) of at least one polyhydrroxyl compound other than b1) having a molecular weight of 62 to about 12,000, wherein the equivalent ratio of isocyanate groups to hydroxyl groups is at least 1.8:1, and
• (II) an isocyanate-reactive component comprising at least one compound having a molecular weight of 400 to about 12,000 which contains at least two isocyanate-reactive groups and, optionally, at least one compound having a molecular weight of 32 to 399 which contains at least two isocyanate reactive groups.