Absorbent fibrous sheet material and process of manufacturing the same

Claim 1

A PROCESS FOR THE MANUFACTURE OF HIGHLY WATER ABSORBENT, FLEXIBLE, POROUS, FIBROUS SHEET MATERIAL OF HIGH TENSILE STRENGTH AND ABRASION RESISTANCE, WHICH PROCESS COMPRISES FIRST PRESTABILIZING A LOOSE FLEECE OF INTERMINGLED, POLYPOSED, FINE, CARDABLE FIBERS CONTAINING AT LEAST A MAJOR AMOUNT OF FIBERS CAPABLE OF SWELLING IN WATER, BY A TREATMENT INCLUDING THE STEPS OF UNIFORMLY THROUGH IMPREGNATING SUCH FLEECE WITH A DILUTE AQUEOUS VULCANIZABLE RUBBER LATEX AND CONDENSING THE FLEECE TO A SHEET, DRYING THE SHEET WITHOUT PRESSURE TO CAUSE DEPOSITION OF ABOUT 20 TO ABOUT 133 PARTS BY WEIGHT OF NONPOROUS RUBBER PARTICLES PER 100 PARS BY WEIGHT OF FIBERS THROUGHOUT THE FLEECE, AND MAINLY AT THE CROSSING POINTS BETWEEN THE FIBERS, IN SUCH MANNER THAT THE FIBERS ARE CEMENTED TOGETHER AT THEIR CROSSING POINTS AND NUMEROUS RELATIVELY LARGE INTERSTICES ARE RETAINED BETWEEN THE FIBERS IN THE PLANE OF THE SHEET, AND, THEREAFTER, REINFORCING THE RESULTING PRESTABILIZED SHEET MATERIAL BY PRESSING INTO IT, THROUGH AT LEAST ONE SURFACE THEREOF, A VULCANIZABLE RUBBER LATEX IN THE FORM OF A HEAVY, FLOWABLE AQUEOUS SUSPENSION CONTAINING ABOUT 8% TO 20% BY WEIGHT OF VULCANIZABLE RUBBER SOLIDS, AND BETWEEN ABOUT 100 PARTS AND 275 PARTS BY WEIGHT OF A FILLER PER 100 PARTS OF RUBBER SOLIDS, SAID FILLER BEING SELECTED FROM THE GROUP CONSITING OF A HIGH MOLECULAR CARBOHYDRATE SUBSTANCE AND MIXTURES OF SAID CARBOHYDRATE SUBSTANCES WITH NOT MORE THAN ABOUT TWICE THEIR WEIGHT OF WATER-SOLUBLE ALKALI METAL SALTS, DRYING AGAIN TO CAUSE DEPOSITION ON THE FIBERS AND ON THE PREVIOUSLY DEPOSITED NON-POROUS RUBBER PARTICLES OF ADDITONAL VULCANIZABLE RUBBER PARTICLES HAVING COLLOIDAL FILLER MATERIAL DISPERSED THERETHROUGH, THE QUANTITY OF SAID COATING PARTICLES BEING SUFFICIENT TO EFFECT A REINFORCEMENT OF THE FIBER SKELETON BUT INSUFFICIENT TO FILL THE INTERSTICES BETWEEN THE FIBERS, SUBJECTING THE MATERIAL TO AN ELEVATED TEMPERATURE WITHOUT PRESSURE TO EFFECT SUBSTANTIALLY COMPLETE VULCANIZATION OF THE VULCANIZABLE RUBBER MATERIAL, THEN TREATING THE SHEET MATERIAL WITH WATER TO ELIMINATE THE FILLER MATERIAL, AND FINALLY DRYING TO PRODUCE A SHEET MATERIAL STABILIZED BY NONPOROUS RUBBER PARTICLES AND REINFORCED BY MICROPOROUS RUBBER COATING PARTICLES AND IN WHICH THE MICROPOROUS IN THE REINFORCING COATING PARTICLES COMMUNICATE WITH THE INTERSTICES BETWEEN THE FIBERS.