US 4,036,679 AGranted

Process for producing convoluted, fiberized, cellulose fibers and sheet products therefrom

AssigneeCrown Zellerbach Corporation

InventorsSangho E. Back, Imants Reba

Life of this patent

Estimating the term…

Loading patent…

Abstract

A process is provided for producing novel convoluted, fiberized substantially nonfibrillated, cellulose fibers and novel sheet products from low moisture-content cellulose pulp, at a high through-put rate, which includes the application of contortive forces to a pulp mass under controlled operating conditions, wherein the feed rate, work space gap, and relative rate of movement of the working elements applying the contortive forces are correlated to maintain the work space filled with fibers under sufficient compression. Sheets made from these fibers exhibit excellent bulk, softness and absorbency properties, even when the formation process is conducted in an aqueous system, and even when substantial compacting forces are applied to the wet web processing.

Claims22

Dependent claims

A process for producing convoluted, fiberized cellulose fibers which are twisted and bent in a substantially lasting manner, without appreciable reduction of fiber length or freeness, comprising subjecting low moisture content cellulose pulp at a consistency of from about 70%, up to about 90% by weight, based on the dry basis weight of the pulp, said consistency being sufficient to preclude substantial fibrillation and the attendant strength and bonding development, while at the same time preventing fiber damage and scorching, to mechanical treatment which gives rise to structural deformation of the fibers causing them to become convoluted and at the same time fiberizing and fluffing the pulp, the mechanical treatment including continuously feeding the pulp at a relatively high through-put rate into and through a work space formed between opposed, spaced-apart working elements to a point of discharge from the work space, the elements including opposed surfaces capable of engaging the pulp, the feeding step being conducted at a rate correlated with the rate of relative movement of the working elements and the spacing between the working surfaces so as to maintain the work space filled with a mass of fibers under sufficient compression so that the pulp is engaged by the working surfaces and contortive forces are imparted to the fibers which are effective to produce convoluted, fiberized fibers which are substantially nonfibrillated.

A process for making a soft, absorbent, bulky paper sheet which comprises:

a. producing convoluted, fiberized cellulose fibers which are twisted and bent in a substantially lasting manner, without appreciable reduction of fiber length or freeness, by subjecting low moisture content cellulose pulp at a consistency of from about 70%, up to about 90% by weight, based on the dry basis weight of the pulp, said consistency being sufficient to preclude substantial fibrillation and the attendant strength and bonding development, while at the same time preventing fiber damage and scorching, to mechanical treatment which gives rise to structural deformation of the fibers causing them to become convoluted and at the same time fiberizing and fluffing the pulp, the mechanical treatment including continuously feeding the pulp at a relatively high through-put rate into and through a work space formed between opposed, spaced-apart working elements to a point of discharge from the work space, the elements including opposed surfaces capable of engaging the pulp, the feeding step being conducted at a rate correlated with the rate of relative movement of the working elements and the spacing between the working surfaces so as to maintain the work space filled with a mass of fibers under sufficient compression so that the pulp is engaged by the working surfaces and contortive forces are imparted to the fibers which are effective to produce convoluted, fiberized fibers which are substantially nonfibrillated;
b. forming an aqueous fiber furnish including said convoluted, fiberized cellulose fibers;
c. forming a wet web from said aqueous fiber furnish;
and
d. thermally drying said wet web to form said soft, absorbent, bulky paper sheet, said sheet having a basis weight of from about 5 pounds per 3,000 square feet up to about 100 pounds per 3,000 square feet, and a bulk softness of from about 0.25 HOM/(caliper).sup.2 .times. 10.sup.5 up to about 1.25 HOM/(caliper).sup.2 .times. 10.sup.5.

2 more elements

Dependencies are inferred from the claim text.