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US 8,177,938 B2Granted
Method of making regenerated cellulose microfibers and absorbent products incorporating same
AssigneeGeorgia-Pacific Consumer Products LP
InventorDaniel W. Sumnicht
Life of this patent
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Abstract
A method of making regenerated cellulose microfibers includes forming segmented fibers with multiple longitudinally-extending segments of slightly different composition such that there is defined splittable interfaces between juxtaposed segments of the fibers which are then split into microfibers at yields of greater than 50%. Fibers so produced may be incorporated into absorbent sheet with other papermaking fibers to provide strength, softness, bulk and absorbency to tissue, towel, and personal care products.
Claims49
A method of making microfibers of regenerated cellulose comprising:
- a) preparing a first cellulosic dope having a first composition;
- b) preparing a second cellulosic dope having a second composition which differs from the first composition of the first cellulosic dope;
- c) spinning the first and second cellulosic dopes into composite nascent fibers each having a length and a segmented cross-section comprising a plurality of segments across the cross-section of the nascent fiber, the segments also extending along the length of the fiber and the nascent fibers including at least one longitudinally-extending segment formed from the first cellulosic dope juxtaposed with at least one longitudinally-extending segment formed from the second cellulosic dope;
- d) regenerating the nascent fibers to splittable composite regenerated cellulose fibers each having a plurality of regenerated cellulose segments across the cross section of the regenerated fiber, the segments also extending along the length of the fiber and including at least a first longitudinally-extending regenerated cellulose segment formed from the first cellulosic dope juxtaposed with at least a second longitudinally-extending regenerated cellulose segment formed from the second cellulosic dope, wherein the first longitudinally-extending regenerated cellulose segment is joined to the second longitudinally-extending regenerated cellulose segment along a splittable interface;
- and
- e) splitting the composite regenerated cellulose fibers into microfibers of smaller cross-section along the splittable interface between segments,
- wherein the geometry of the nascent fibers is regulated, the first and second cellulosic dope compositions are cellulosic dopes without other fiber-forming components, and are selected, and the steps of regenerating and splitting the fibers are controlled, such that the composite regenerated cellulose fibers are split into micro fibers with a coarseness between 0.05 mg/100 m and 10 mg/100 m with a microfiber yield of more than 50% based on larger splittable regenerated cellulose composite fibers subjected to step (e) and said microfibers have a length weighted average length of from about 20% to about 50% of said larger splittable regenerated cellulose composite fibers.
4 more elements
A method of making microfibers of regenerated cellulose comprising:
- a) preparing a first cellulosic dope comprising cellulose dissolved in a solvent including an ionic liquid, the first cellulosic dope having a first composition;
- b) preparing a second cellulosic dope comprising cellulose dissolved in a solvent including an ionic liquid, the second cellulosic dope having a second composition which differs from the first composition of the first cellulosic dope;
- c) spinning the first and second cellulosic dopes into composite nascent fibers each having a length and a segmented cross-section comprising a plurality of segments across the cross-section of the nascent fiber, the segments also extending along the length of the fiber and the nascent fibers including at least one longitudinally-extending segment formed from the first cellulosic dope juxtaposed with at least one longitudinally-extending segment formed from the second cellulosic dope;
- d) regenerating the nascent fibers to splittable composite regenerated cellulose fibers each having a plurality of regenerated cellulose segments across the cross section of the regenerated fiber, the segments also extending along the length of the fiber and including at least a first longitudinally-extending regenerated cellulose segment formed from the first cellulosic dope juxtaposed with at least a second longitudinally-extending regenerated cellulose segment formed from the second cellulosic dope, wherein the first longitudinally-extending regenerated cellulose segment is joined to the second longitudinally-extending regenerated cellulose segment along a splittable interface;
- and
- e) splitting the composite regenerated cellulose fibers into microfibers of smaller cross-section along the splittable interface between segments and having a length weighted average length of from about 20% to about 50% of said larger splittable regenerated cellulose composite fibers,
- wherein said first cellulosic dope and second cellulosic dope are cellulosic dopes without other fiber-forming components.
4 more elements
A method of making a wet-laid absorbent sheet comprising:
- (a) preparing regenerated cellulose micro fibers fibers by way of:
- i) preparing a first cellulosic dope having a first composition;
- ii) preparing a second cellulosic dope having a second composition which differs from the first composition of the first cellulosic dope;
- iii) spinning the first and second cellulosic dopes into composite nascent fibers each having a length and a segmented cross-section comprising a plurality of segments across the cross-section of the nascent fiber, the segments also extending along the length of the fiber and the nascent fibers including at least one longitudinally-extending segment formed from the first cellulosic dope juxtaposed with at least one longitudinally-extending segment formed from the second cellulosic dope;
- iv) regenerating the nascent fibers to splittable composite regenerated cellulose fibers each having a plurality of regenerated cellulose segments across the cross section of the regenerated fiber, the segments also extending along the length of the fiber and including at least a first longitudinally-extending regenerated cellulose segment formed from the first cellulosic dope juxtaposed with at least a second longitudinally-extending regenerated cellulose segment formed from the second cellulosic dope, wherein the first longitudinally-extending regenerated cellulose segment is joined to the second longitudinally-extending regenerated cellulose segment along a splittable interface;
- and
- v) splitting the composite regenerated cellulose fibers into microfibers of smaller cross-section along the splittable interface between segments, wherein the geometry of the nascent fibers is regulated, the first and second cellulosic dope compositions are selected, and the steps of regenerating and splitting the fibers are controlled, such that the composite regenerated cellulose fibers are split into microfibers with a coarseness between 0.05 mg/100 m and 10 mg/100 m with a microfiber yield of at least 50% based on larger splittable regenerated cellulose composite fibers subjected to step (a)(v), and having a length weighted average length of from about 20% to about 50% of said larger splittable regenerated cellulose composite fibers;
- (b) preparing an aqueous furnish incorporating the regenerated cellulose microfibers made by step (a) as well as pulp-derived papermaking fibers;
- (c) depositing the aqueous furnish on a foraminous support to form a nascent web and at least partially dewatering the nascent web;
- and
- (d) drying the web to provide absorbent sheet,
- wherein said first cellulosic dope and second cellulosic dope are cellulosic dopes without other fiber-forming components and micro fibers.
9 more elements
Dependencies are inferred from the claim text.