Process for forming a flexible polyurethane coating

Claim 1

IN THE PROCESS FOR FORMING A FLEXIBLE POLYURETHANE COATING OR FILM INCLUDING THE STEPS OF CONTINUOUSLY INTRODUCING POLYURETHANE-FORMING REAGENTS FROM SUPPLY CONTAINERS TO A MIXING ZONE UNDER TEMPERATURE CONDITIONS MAINTAINING SAID REAGENTS IN LIQUID CONDITION, MIXING SAID REAGENTS IN SAID ZONE, CONTINUOUSLY DISCHARGING THE MIXED REAGENT FROM SAID ZONE AS A SUBSTANTIALLY SOLVENT FREE LIQUID CONTINUOUS STREAM OF A MIXTURE OF SAID REGENTS, SAID REGENTS COMPRISING A POLYISOCYANATE, A DIFUNCTIONAL AMINE IN AMOUNT EQUIVALENT TO FORM ABOUT 5 TO ABOUT 35 PERCENT OF THE REACTIVE :NCO OF SAID POLYISOCYANATE AND A DIOL HAVING A MOLECULAR WEIGHT OF FROM ABOUT 500 TO ABOUT 3,000, THE REACTIVE HYDROGEN OF SAID DIOL AND AMINE BEING SUBSTANTIALLY EQUIVALENT TO THE REACTIVE -NCO GROUPS OF SAID POLYISOCYANATE AND SAID MIXTURE BEING REACTIVE TO FORM A PSEUDOPLASTIC INTERMEDIATE STAGE MATERIAL HAVING AN EXTREMELY HIGH VISCOSITY AT WHICH IT WILL NOT DIVE INTO POROSITIES ON A CASTING SURFACE AT SHEAR RATES APPROCHING ZERO AND VERY MUCH LOWER VISCOSITY SUITABLE FOR BLENDING, SPREADING AND COATING UNDER SHEARING AGITATION, DEPOSITING SAID STREAM OF MIXED REACTANTS ON A CONTAINOUSLY MOVING SURFACE WHOSE PATH LEADS BENEATH A SPREADER ELEMENT AND THEN THROUGH A HEATED CURING ZONE, SAID SPREADER ELEMENT EXTENDING ACROSS SAID SURFACE AND BEING DISPOSED RELATIVE TO SAID SURFACE TO FORM A LAYER ON SAID SURFACE BY ALLOWING PASSAGE BETWEEN SAID ELE-MENT AND SAID SURFACE OF A THICKNESS OF SAID MIXTURE ON SAID SURFACE DETERMINED BY THE DESIRED THICKNESS OF SAID COATING OR FILM AND TO HOLD BACK PASSAGE OF MIXED REACTANTS ON SAID SURFACE GREATER THAN SAID DETERMINED THICKNESS ABOVE SAID SURFACE, REACTING SUCCESSIVE PORTIONS OF SAID MIXTURE OF REAGENTS TO SAID PSEUDOPLASTIC INTERMEDIATE STATE WHILE BEING MOVED TOWARD SAID SPREADER ELEMENT, COLLECTING ON SAID SURFACE MIXED MATERIAL HELD BACK BY SAID SPREADER ELEMENT AS A BANK, THE RELATIVE MOVEMENT BETWEEN SAID SURFACE AND SAID SPREADER ELEMENT CREATING SHEARING AGITATION IN AND A ROLLING MOVEMENT OF SAID BANK TO PROVIDE SAID LOWER VISOCSITY STATE IN THE MATERIAL IN SAID BANK, CONTINUOUSLY INCORPORATING AND BLENDING FURTHER MIXTURE FROM SAID SURFACE INTO THE MASS OF REACTIVE MIXTURE IN SAID BANK, SPREADER ELEMENT, WITHDRAWING BANK ON SAID SURFACE BY SAID SPREADER ELEMENT, WITHDRAWING PORTIONS OF THE BLENDED MATERIAL ON SAID SURFAE FROM THE AGITATED MASS IN SAID BANK AS A LAYER PASSING BENEATH SAID SPREADER ELEMENT WHILE THE MASS REMAINS SPREADABLE THROUGH BALANCE OF FRESHLY MIXED AGAINST PREVIOUSLY MIXED REAGENTS AND DOES NOT SET UP, CONTROLLING THE SIZE OF THE AGITATED MASS IN SAID BANK BY CORRELATION OF THE RATE OF SUPLY OF THE MIXTURE OF REGENTS TO SAID SURFACE AND THE RATE OF WITHDRAWAL TO PROVIDE DWELL TIME OF REACTIVE MIXTURE IN SAID BANK, THE VISCOSITY OF SAID MIXTURE IN SAID LAYER BECOMING EXTREMELY HIGH WHEN THE LAYER HAS LEFT THE SPERADER ELEMENT AND SHEARING AGITATION CEASES, AND THEN HEATING SAID LAYER TO CURING TEMPERATURE DURING PASSAGE ON SAID SURFACE THROUGH SAID HEATED CURING ZONE.