Method of applying a liquid coating to a flexible web

A method of simultaneously applying a plurality of liquids (18 and 19) to a surface of a flexible carrier (6), said method comprising the steps of:

• providing an extrusion application head (1) including two or more doctor edge portions, each of said doctor edge portions being separated by a slot (15 and 16) having an outlet portion, said doctor edge portions each including an application surface, said extrusion head also including a back edge portion (12) including a front, angled, planar surface adjacent to a curved, upper surface so as to form a scraping edge (9);
• providing said curved, upper surface of said back edge portion of said extrusion application head with a radius of curvature of 0.5 to 10 mm, so that a relief angle of said carrier to a tangent on said curved, upper surface of said back edge portion at said scraping edge is 0.degree. to 15.degree.;
• pushing said extrusion application head toward said surface of said carrier such that said curved, upper surface of said back edge portion (12), including said scraping edge (9), said application surface and said slot outlet portions are urged against and enveloped by said carrier to deflect said carrier, said carrier having a tension of 5 to 30 kg/m;
• continuously conveying said carrier;
• applying a liquid undercoating (17) in excess to said surface upstream and in advance of said extrusion application head relative to a conveyance direction (A) of said carrier so as to form a liquid undercoating layer on said surface of said carrier;
• scraping the excess liquid undercoating from said carrier by conveying said carrier along a surface of said back edge portion of said head such that said scraping edge (9) scrapes off the excess undercoating liquid to prevent air from entering between said application surface and said carrier;
• removing said excess undercoating, said excess undercoating flowing down said front, angled, planar surface of said back edge portion;
• and
• continuously jetting out said plurality of liquids from said slots so that said plurality of liquids are simultaneously applied to said liquid undercoating layer to form mutually-overlaid layers of said liquids on said surface of said carrier.