US 4,440,597 AGranted

Wet-microcontracted paper and concomitant process

AssigneeThe Procter & Gamble Company

InventorsEdward R. Wells, Thomas A. Hensler

Life of this patent

Estimating the term…

Loading patent…

Abstract

High bulk, absorbent paper having a relatively high MD elongation at rupture, and a substantially greater stress/strain modulus in the lowest one-third of its range of MD extensibility--preferably when wet--than equally machine-direction-stretchable, purely dry-foreshortened (e.g., dry-creped) paper having substantially identical MD elongation at rupture. The process includes a differential velocity transfer of a wet-laid embryonic web having relatively low fiber consistency from a carrier to a substantially slower moving, open-mesh transfer fabric having a substantial void volume; and thereafter drying the web while precluding substantial macroscopic rearrangement of the fibers in the plane of the web. The differential velocity transfer is effected without substantial compaction of the web by avoiding substantial mechanical pressing, centrifugal slinging, air blasting, and the like. The MD stress-strain property of the paper when wet is directly related to the magnitude of the differential velocity at transfer; to the magnitude of the wet-strength property of the paper; and to the topography of the transfer fabric.

Claims27

Dependent claims

A process for making high bulk, MD-extensible tissue paper having a predetermined MD stress/strain modulus substantially different from comparably extensible dry-creped paper, said MD stress/strain modules being substantially greater than for said comparably extensible dry-creped paper through their lowest one-third ranges of MD extensibility, said process comprising the steps of:

forming an embryonic paper web from an aqueous fibrous papermaking furnish;
forwarding said embryonic web at a first velocity on an endless carrier fabric to a transfer zone;
non-compressively removing sufficient water from said embryonic web that it has a fiber consisting of from about ten (10) to about thirty (30) percent immediately prior to its reaching said transfer zone to enable said embryonic web to be transferred to an endless foraminous transfer fabric at said transfer zone, said transfer fabric having a sufficiently greater void volume than said carrier fabric to obviate macrofolding of said web;
forwarding at a second velocity said endless foraminous transfer fabric along a looped path in contacting relation with a transfer head disposed at said transfer zone, said transfer head having a convex fabric-contacting surface, said second velocity being substantially less than said first velocity;
guiding said carrier fabric and said transfer fabric to cause them to converge and then diverge at acute angles while traversing said convex surface, said acute angles being sufficiently small and the curvature of said convex surface being sufficiently large to substantially obviate fabric-tension-induced compaction of said embryonic web as it passes through said transfer zone;
applying only a sufficient level of differential gaseous pressure across said embryonic web at said transfer zone to cause said embryonic web to transfer to said transfer fabric in said transfer zone without precipitating substantial compaction of said embryonic web;
and
completing the papermaking-machine drying of said embryonic web while maintaining the macroscopic interfiber relationships therein in the plane of the web and without overall mechanical compaction of the web.

5 more elements

Wet-microcontracted tissue paper having high bulk, substantial machine-direction extensibility, and being characterized by a substantially greater stress/strain modulus through its lowest one-third range of MD extensibility than comparably extensible dry-creped paper which is otherwise substantially identical tissue paper, said wet-microcontracted tissue paper being made by the process comprising the steps of:

forming an embryonic paper web from an aqueous fibrous papermaking furnish;
forwarding said embryonic web at a first velocity on an endless carrier fabric to a transfer zone;
non-compressively removing sufficient water from said embryonic web that it has a fiber consistency of from about ten (10) to about thirty (30) percent immediately prior to its reaching said transfer zone to enable said embryonic web to be transferred to an endless foraminous transfer fabric at said transfer zone, said transfer fabric having a sufficiently greater void volume than said carrier fabric to obviate macrofolding of said web;
forwarding at a second velocity said endless foraminous transfer fabric along a looped path in contacting relation with a transfer head disposed at said transfer zone, said transfer head having a convex fabric-contacting surface, said second velocity being substantially less than said first velocity;
guiding said carrier fabric and said transfer fabric to cause them to converge and then diverge at acute angles while transversing said convex surface, said acute angles being sufficiently small and the curvature of said convex surface being sufficiently large to substantially obviate fabric-tension-induced compaction of said embryonic web as it passes through said transfer zone;
applying only a sufficient level of differential gaseous pressure across said embryonic web at said transfer zone to cause said embryonic web to transfer to said transfer fabric in said transfer zone without precipitating substantial compaction of said embryonic web;
and
completing the papermaking-machine drying of said embryonic web while maintaining the macroscopic interfiber relationships therein in the plane of the web and without overall mechanical compaction of the web.

5 more elements

Dependencies are inferred from the claim text.