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AssigneeRhodia Chimie
InventorsJEAN-MARIE BERNARD, JEAN-PIERRE CORBET, MINOU NABAVI, PHILIPPE GALY-JAMMOU, DENIS REVELANT
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This invention relates to a process for the preparation of aqueous emulsions of blocked (poly)isocyanates, this process comprising the steps consisting successively in: a) placing an isocyanate composition containing free isocyanate functions in contact with at least one blocking agent A in the presence of a surfactant B and an aqueous phase, the said isocyanate composition being added gradually to a stock containing at least some of the aqueous phase and at least some of the blocking agent; and optionally, b) subjecting the mixture obtained to a shear (speed gradient) of greater than 1000 s−1, preferably greater than 20,000 s−1 and less than 1,000,000 s−1, preferably less than 200,000 s−1, and c) repeating step b), optionally after step a) has been repeated, until a stable emulsion is obtained whose particles have a Sauter diameter of greater than 0.1 μm, preferably 0.2 μm, and less than 5 μm, preferably less than 2 μm, and a dispersion width of less than 5 μm.
Process for the preparation of an emulsion of blocked (poly)isocyanates, this process comprising the step consisting in:
Use of ionic surfactant for an isocyanate blocking in emulsion, characterized in that the said surfactant contains a compound containing an anionic function and advantageously a polyethylene glycol and/or polypropylene glycol chain fragment of at least one, preferably of at least 5, oxyethylene and/or oxypropylene units.
Composition containing a blocked polyisocyanate emulsion, characterized in that it contains a surfactant comprising an anionic function and a polyethylene glycol and/or polypropylene glycol chain fragment of at least 1, preferably at least 5 oxyethylene and/or oxypropylene units, said surfactant being present in free form and optionally also bound to the polyisocyanate, with the proviso that when the mean diameter of the particles of the emulsion is less than 5 μm, said surfactant does not contain sulfate groups.
Composition according to any one of the preceding claims, characterized in that the surfactant is of the following formula
Dependencies are inferred from the claim text.