| 摘要 |
To coat a flexible web (19) with wet layers, the first layer (23) is spread over the film surface by a gravure roller (12), followed by an extruder (30) with upstream (31) and lower (32) lips to deliver the second layer (39). To coat a flexible web (19) with wet layers, the first layer (23) is spread over the film surface by a gravure roller (12), followed by an extruder (30) with upstream (31) and lower (32) lips to deliver the second layer (39). The upstream extruder lip is formed by a surface at right angles to the film web movement, with side edges shaped so that part of the lip surface has a convex curvature radius in relation to the web which is not more than 200 mm. The downstream extruder lip runs straight on the web movement line, and the sides are shaped to form a guide edge. The downstream lip is further displaced from the web than an upstream lip at a tangent to the trailing edge of the upstream lip. The surface of the downstream lip leads from the guide edge to the peak of a convex curve with a curvature radius which is 0.2-2.0 times the curvature radius of the upstream lip. The extruder lips are at a holder so that the first wet layer remains in contact with part of the upstream lip surface. At the coating station, the draw tension is applied to the web while on an unsupported path. The extruder is carried by a holder so that the unsupported web is in contact with the upstream lip surface and deflects the web in a curve with a curvature radius of not more than 50 mm, and to pass the web round the lip by an angle of at least 2 deg while remaining in contact. The web has a tangential contact with the downstream lip surface. The first wet layer is a dispersion of particles with a bonding agent, and the coating is in contact with the upstream lip while passing round it at an angle of at least 5 deg .
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