BigPatents India

A method for coating a substrate includes rotating the substrate about an axis, and applying a polymeric reaction mixture to a surface of the rotating substrate by ejecting the polymeric reaction mixture through a die. The die has a branched system of channels for dividing an inlet stream of the polymeric reaction mixture into plural outlet streams. The outlet streams are spaced apart from each other such that the outlet streams flow together seamlessly after application to the substrate. The die and the rotating substrate are moved longitudinally relative to each other. And the material output rate of the mixture and the relative movement of the die are synchronized with the rotational speed of the substrate in such a way that successive convolutions of polymeric reaction mixture overlap and connect together seamlessly.