FIELD: chemistry.
SUBSTANCE: present invention relates to a method of preparing a reactive polyurethane composition, as well as a reactive polyurethane composition prepared using the said method, and to use of the said composition as a single-component reactive adhesive or as a coating. The polyurethane composition is obtained in two steps, where the first and/or second step takes place at temperature between 80 and 140 °C. Monomer-free thermoplastic polyurethane containing groups which are reactive towards isocyanate is obtained at the first step. A polymer or a mixture of polymers containing at least 90 wt % linear molecules, both reactive towards isocyanate, reacts with polyisocyanate with molecular weight <500 in molar deficiency of isocyanate groups in polyisocyanate relative terminal groups of a polymer or mixture of polymers which are reactive towards isocyanate. At the second step, the obtained thermoplastic polyurethane reacts with a prepolymer with low monomer content and with terminal isocyanate groups. Molar ratio of thermoplastic polyurethane terminal groups which are reactive towards isocyanate to prepolymer isocyanate groups ranges from 1:1.1 to 1:5.
EFFECT: obtained reactive polyurethane compositions have low residual content of diisocyanate monomers which may not be specially labelled, and also have high initial strength which facilitates their efficient use as single-component hot melt adhesives or coatings.
21 cl, 4 ex, 1 tbl
