Continuous casting process

Claim 1

A PROCESS FOR PREPARING SUBSTANTIALLY RIGID SHEETS AND THE LIKE COMPRISES PASSING A FLUID COMPOSITION COMPRISING A POLYMERIZABLE ORGANIC MONOMER BETWEEN AND IN CONTACT WITH TWO MOVING SURFACES, PROVIDING A PAIR OF SEALS BETWEEN SAID SURFACES SUCH THAT SAID FLUID COMPOSITION IN CONFINED IN A SPACE BOUNDED ON TWO OPPOING SIDES BY SAID SEALS, ASLLOWING SAID FLUID TO FILL THE CAVITY DEFINED BY SAID SURFACES AND SAID SEALS, PASSING SAID COMPOSITION AND MOVING SURFACES THROUGH AT LEAST ONE ZONE IN WHICH SAID COMPOSITION IS SUBJECTED TO CONDITIONS WHICH CAUSE SAID MONOMER TO POLYMERIZE, ONE OF SAID SURFACES BEING DISPOSED ABOVE THE OTHER OF SAID SURFACES IN SAID ZONE, SAID UPPER SURFACE BEING OF SUCH A SIZE AND WEIGHT THAT IT WOULD BOW DOWNWARDLY INTO SAID FLUID AND TOWARD SAID SECOND SURFACE IF SAID SURFACES WERE HORIZONTAL IN SAID ZONE, MAINTINING THE PATH OF SAID SURFACES THROUGH SAID ZONE AT AN INCLINE TO THE HORIZONTAL TO CAUSE A FLUID HEAD TO BE DEVELOPED BY SAID FLUID COMPOSITION, SAID INCLINE BEING SUFFICIENT FOR THE FLUID PRESSURE BETWEEN SAID SURFACES TO MAINTAIN SAID SURFACES SUBSTANTIALLY PARALLEL TO EACH OTHER AND THE SPACING BETWEEN SAID SURFACES AT A PREDETERMINED DISTANCE, BRINGING SAID SURFACES TOGETHER TO AN EXTENT SUFFICIENT TO COMPENSATE FOR ANY SHRINKAGE OF THE COMPOSITION DURING POLYMERIZATION SUCH THAT SAID SURFACES ARE MAINTAINED IN CONTACT WITH SAID COMPOSITION DURING POLYMERIZATION, AND REMOVING THE RESULTANT POLYMERIZED SHEET FROM BOTH OF SAID SURFACES.