Process for the preparation of continuous optical compensatory sheet

A process for the preparation of a continuous optical compensatory sheet comprising the continuous steps of:

• i) coating a coating liquid of a resin for forming an orientation layer in a solvent on a surface of a moving continuous transparent film to form a coated layer;
• ii) drying the coated layer to form a transparent resin layer;
• iii) bringing a surface of the transparent resin layer into contact with a rubbing sheet of a rubbing roller having the rubbing sheet thereon under revolution while removing dust on the rubbing sheet by use of an ultrasonic dust-removing machine to impart orientation property to the transparent resin layer, whereby an orientation layer is obtained;
• iv) removing dust from the rubbed orientation layer by using an ultrasonic dust-removing machine;
• v) coating a coating liquid of a discotic compound having liquid crystalline property in a solvent on the orientation layer to form a coated discotic compound layer;
• vi) drying the coated discotic compound layer;
• vii) heating the coated discotic compound layer to form a discotic nematic phase, whereby a layer of discotic compound is formed;
• and
• viii) winding up the transparent film having the orientation layer and the layer of discotic compound.