Solid, water-dispersible plastics precursors containing isocyanate groups, a process for the production of aqueous plastics dispersions using such plastics precursors

DETAILED DESCRIPTION OF THE INVENTION The plastics precursors according to the present invention are produced by the methods known in polyurethane chemistry, i.
e.
by reacting organic polyisocyanates with compounds containing isocyanate-reactive groups and optionally using starting materials containing hydrophilic groups or groups convertible into hydrophilic groups, particularly when the above-mentioned starting materials do not contain any such groups.
Suitable polyisocyanates are any of the polyisocyanates commonly encountered in polyurethane chemistry, as described for example in U.
S.
Pat.
No.
3,756,992, incorporated herein by reference, at column 6, line 45 to column 7, line 19, although it is preferred to use the diisocyanates preferably used in polyurethane chemistry, such as 2,4- and/or 2,6-diisocyanatotoluene, 4, 4'-diisocyanatodiphenyl methane or a mixture thereof with 2,4-diisocyanatodiphenyl methane, 4,4-diisocyanatodicyclohexyl methane or a mixture thereof with 2,4'-diisocyanatodicyclohexyl methane, hexamethylene diisocyanate or 1- socyanato-3, 3, 5-trimethyl-5-isocyanatomethyl cyclohexane (isophorone diisocyanate or IPDI).
The particularly preferred starting diisocyanates are difunctional, aliphatic or cycloaliphatic and have a molecular weight from about 168 to 300.
Compounds containing isocyanate-reactive groups which are suitable for use in the production of the plastics precursors according to the present invention are the conventional synthesis components used in polyurethane chemistry which contain carboxyl groups, primary and/or secondary amino groups and, in particular, alcoholic hydroxyl groups and which have a molecular weight of from about 32 to 2500, preferably from about 62 to 1000.
Providing the functionality thereof is known, the molecular weight of the relatively high molecular weight synthesis components falling within the scope of this definition may be determined from the functional group content thereof.
If the functionality thereof is not known (for example higher polyester polyols), the molecular weight of these synthesis components may be determined by osmometry