Microcellular spheres of uncurees

Claim 1

THE PREPARATION OF PLASTIC BALLOON HAVING DIAMETERS BETWEEN ABOUT 0.003 AND 0.03 INCH WHICH COMPRISES: (1) ADMIXING AN UNCRUED METHYLOLAMINE RESIN IN POWDERED SOLID FORM PASSING AN 8 BUT RETAINED ON A 200 MESH SCREEN, SAID RESIN BEING CHARACTERIZED BY THE RELEASE OF A GAS UPON HEATING AND BEING SELECTED FROM THE GLASS CONSISTING OF UREA-FORMALDEHYDE, MELAMINE-FOMALDEHYDE AND GUANAMINE-FOMALDEHYDE SOLID RESINS WITH A DISPERSING POWDERED SOLID THAT PASSES A 3 MESH SCREEN AND THAT IS INERT TO THE HEATING CONDITIONS HEREIN SET FORTH IN STEP (2), THE AMOUNT OF SAID RESIN COMPRISING FROM ABOUT 25 TO 60 WEIGHT PERCENT OF THE ADMIXTURE OF SAID RESIN AND SAID POWDERED SOLID SO THAT SAID POWDERED THREBY PREVENTS CONTACT BETWEEN THE INDIVIDUAL POWDERS OF SAID RESIN; (2) HEATING SAID ADMIXTURE OF SOLIDS TO A TEMPERATURE BETWEEN ABOUT 250* AND ABOUT 600*F. UNDER HEATING CONDITIONS SUFFICIENT TO COMPELTELY CURE SAID RESIN BUT INSUFFICIENT TO AGGLOMERATE AND SINTER SAID RESIN PARTICLES TO THEREBY FORM DISCRETE, NON-SINTERED PLASTIC BALLOONS DISPERSED THROUGHOUT SAID INERT POWDERED SOLID; AND (3) THEREAFTER SEPARTING SAID PLASTIC BALLOONS FROM SAID INERT SOLID POWDER.