Continuous prodn. of poly:methyl methacrylate! sheet - using a polymerisation chamber of endless belts sepd. by continuous seals

摘要

The process comprises polymerising methylmethacrylate (opt. together with a copolymerisable monomer) or a prepolymer of this in a space defined by two opposing endless belts, held at a predetermined distance apart by endless seals at the edges, which move together with the endless belts. The monomer is first introduced into the space and polymerised by contacting the outside of the endless belts and seals with hot water. The water is then removed, first from the surface of the belts, then from the outside of the belts between the seals. Polymerisation is the completed at 120-160 degrees C and the finished sheet is removed from the space. Successive removal of surplus water from the endless belts and seals prevents water being drawn into the polymerisation space due to the suction effect creasted in the space as the sheet parts from the belt in later stages of the polymerisation. This improves the appearance of the sheets and overcomes marking of the sheets.