Method for making chemically cross-linked cellulosic fiber in the sheet form

Abstract

The present invention is directed to cross-linked cellulosic fiber in the sheet from, obtainable by cross-linking a blend of mercerized pulp and conventional pulp. The method includes heating treated cellulosic fibers to promote intra-fiber cross-linking. The cross-linked fibers are characterized by an improved acquisition rate, resiliency, absorbency, and absorbency under load. Moreover, the inventive cross-linked fibers exhibit a reduction in centrifuge retention capacity, and have low knots, nits and fines contents. The cross-linked cellulosic fibers of the invention are useful in the acquisition layer and/or absorbent core of absorbent articles.

1 . Cross-linked cellulosic fibers comprising a blend of mercerized cellulosic fibers and conventional fibers having an absorbent capacity of at least about 8.0 grams saline/gram of fiber.  
     
     
         2 . The cross-linked fibers of  claim 1  wherein the fibers have a centrifuge retention capacity of less than about 0.6 grams of a 0.9% by weight saline solution per gram of fiber.  
     
     
         3 . The cross-linked fibers of  claim 1 , wherein the fibers have an absorption capacity of at least about 9.0 g saline/g fiber.  
     
     
         4 . The cross-linked fibers of  claim 1 , wherein the fibers have a centrifuge retention of not more than 0.5 g saline/g fiber.  
     
     
         5 . The cross-linked fibers of  claim 1 , wherein the fibers have a free swell of at least about 10.0 g saline/g fiber.  
     
     
         6 . The cross-linked fiber of  claim 1 , wherein the fibers have knots and nits contents of less than about 10%.  
     
     
         7 . The cross-linked fiber of  claim 1 , wherein the fibers have fines contents of less than about 6.5%.  
     
     
         8 - 46 . Cancelled  
     
     
         47 . An absorbent article comprising the cross-linked fiber of  claim 1 .  
     
     
         48 . The absorbent article of  claim 47 , wherein the absorbent article is at least one article selected from the group consisting of infant diapers, feminine care products, training pants, and adult incontinence briefs.  
     
     
         49 . The absorbent article of  claim 47 , further comprising a liquid penetrable top sheet, a liquid impenetrable back sheet, an acquisition layer, and an absorbent structure, wherein the acquisition layer is disposed beneath the top sheet, and the absorbent structure is disposed between the acquisition layer and the back sheet.  
     
     
         50 . The absorbent article of  claim 49 , wherein the acquisition layer comprises the cross-linked fibers.  
     
     
         51 . The absorbent article of  claim 49 , wherein the absorbent structure comprises a composite of superabsorbent polymer and cellulosic fibers.  
     
     
         52 . The absorbent article of  claim 51 , wherein the superabsorbent polymer is selected from the group consisting of polyacrylate polymers, starch graft copolymers, cellulose graft copolymers, cross-linked carboxymethylcellulose derivatives, and mixtures and combinations thereof.  
     
     
         53 . The absorbent article of  claim 51 , wherein the superabsorbent polymer is in the form of fiber, flakes, or granules.  
     
     
         54 . The absorbent article of  claim 51 , wherein the superabsorbent polymer is present in an amount of from about 20 to about 60% by weight, based on the total weight of the absorbent structure.  
     
     
         55 . The absorbent article of  claim 51 , wherein the cellulosic fibers comprise the cross-linked cellulosic fibers.  
     
     
         56 . The absorbent article of  claim 51 , wherein the cellulosic fibers comprises a mixture of the cross-linked cellulosic fibers and cellulosic fibers.  
     
     
         57 . The absorbent article of  claim 56 , wherein the cellulosic fiber is a wood pulp fiber selected from the group consisting of hardwood pulp, softwood cellulose pulp obtained from a Kraft or sulfite chemical process, mercerized, rayon, cotton linters, and combinations or mixtures thereof.  
     
     
         58 . The absorbent article of  claim 57 , wherein the cross-linked cellulosic fiber is present in the mixture of fibers in an amount of from about 1 to 70% by weight, based on the total weight of the mixture of fibers.  
     
     
         59 . The absorbent article of  claim 58 , wherein the cross-linked cellulosic fiber is present in an amount of from about 10 to 40% by weight, based on the total weight of the mixture of fibers.  
     
     
         60 . The absorbent article of  claim 56 , wherein the mixture of cross-linked cellulosic fibers and cellulosic fibers is present in an amount of from about 10 to about 80% by weight, based on the total weight of the absorbent structure.  
     
     
         61 . The absorbent article  claim 60 , wherein the mixture is present in an amount of from about 20 to about 60% by weight, based on the total weight of the absorbent structure.  
     
     
         62 . Cancelled  
     
     
         63 . Cancelled