Importance

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Abstract

For producing a polyurethane layer by spraying a polyurethane reaction mixture, this mixture is supplied under pressure to a spray nozzle, within the nozzle the reaction mixture is accelerated by passing it through one or more channels having a reduced cross-sectional area, and the accelerated reaction mixture is sprayed, with a predetermined amount of kinetic energy, through a spray opening out of the spray nozzle onto a surface. The channels wherein the reaction mixture is accelerated have a total minimum cross-sectional area of S mm², S being a value smaller than 1.0, the reaction mixture is sprayed out of the nozzle at a flow rate of between 10×S and 80×S g/sec, and, per gram reaction mixture, an amount of 0.05 to 2.5 mmol of a pressurized gas is sprayed together with the reaction mixture through said spray opening out of the nozzle to increase the kinetic energy of the reaction mixture which is sprayed out of the nozzle. By the addition of a pressurized gas to the reaction mixture, a same or even a better spray pattern can be achieved and the reaction mixture can be sprayed at a smaller flow rate.

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First Claim