Patent ID: 8299171

Claim:
A spray-polyurethane system, comprising polyol component (A) and an isocyanate component (B), where the polyol component (A) comprises a1) at least one compound reactive with isocyanate, wherein a1) comprises at least one polyether polyol having a number-average molar mass of from 1,500 to 3,500 g/mol and a functionality of 2.0 or smaller, and at least one polyetherol having a number-average molar mass of from 3,000 to 6,000 g/mol and a functionality of 2.2 or greater, a2) from 0.2 to 2.0% by weight based on the weight of the polyol component (A) of at least one reactive chain extender having at least two NH 2 groups reactive toward isocyanates, and a3) at least one tin catalyst wherein no catalyst containing a secondary or tertiary amine is present in said system.