Patent ID: 7230037
Filing Date: 2007-06-12
Classification: B01F,B29B,B29K

Abstract:
1. In a method for the production of a polyurethane foam material, the improvement comprising controlling cell size in the foam made by continuous mixing of at least one polyol component and at least one isocyanate component and optionally additives to form a polyurethane reaction mixture in a stirrer mixer which comprises a cylindrical mixing chamber having a stirrer rotating therein with adjustable rotational speed, the stirrer containing a stirrer shaft and scoops or blades arranged thereon in one or more levels, the stirrer mixer having feed openings for at least the polyol component, the isocyanate component and optionally the additives and an outlet opening for the polyurethane reaction mixture, wherein three to six scoops or blades are arranged in each level on the stirrer shaft such that the scoops or blades are rotated by an angle α of 10° to 80° counter to the axis of rotation of the stirrer shaft, said method comprising: pumping the polyol component, the isocyanate component and optionally the additives in a metered manner through the feed openings into the cylindrical mixing chamber and mixing therein to form the polyurethane reaction mixture; discharging the polyurethane reaction mixture from the mixing chamber through the outlet opening; and reducing the polyurethane reaction mixture pressure In an adjustable throttle, wherein the cell size is controlled by adjusting pressure in the mixing chamber by a mutually matched setting of the rotational speed of the stirrer and of the throttling effect of the throttle.