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

a cellulosic fiber and sheet form technology, applied in papermaking, non-fibrous pulp addition, bandages, etc., can solve the problems of unsuitable applications, time-consuming process, and high cost, and achieve enhanced bulking characteristics, long shelf life, and high stability

Inactive Publication Date: 2005-03-03
HAMED OTHMAN A +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] One feature of an embodiment of the present invention provides cross-linked fibers with enhanced bulking characteristics, porosity and rate of acquisition. An additional aspect of the present invention is to provide cross-linked cellulosic fiber having long shelf-life and high stability. Further, another aspect of an embodiment of the present invention provides fibers useful in an acquisition layer and / or in an absorbent core of absorbent products. Various aspects of the present invention also provide absorbent articles comprising the cross-linked fiber of the present invention.
[0013] In accordance with these and other aspects and features of embodiments of the invention, there is provided a cross-linked sheet of a blend of fibers, and a method for cross-linking cellulose fibers in sheet form. In one aspect of the invention, the cellulose fibers are a blend of mercerized fibers and conventional fibers that are cross-linked. In another aspect of the invention, the cross-linked fibers formed in accordance with the present invention can be easily defiberized without serious fiber breakage and with low knot-content and low nit-content. It will be appreciated, however, that knots and nits are advantageous for some applications, and accordingly, the present invention is not in any way limited to producing cross-linked cellulosic fibers substantially free of knots.

Problems solved by technology

In addition, the long aliphatic chains tend to reduce the fibers' absorbency and acquisition rate, thus rendering the fibers unsuitable for applications where high rate of absorbency and fast acquisition are important, such as in absorbent articles.
The above-described approaches complicate the process of cross-linking fiber in sheet form, and they render the process time consuming, and costly.

Method used

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

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0090] This example illustrates a method for making mercerized fibers and a method for forming handsheets from a blend of mercerized and Rayfloc®-J-LD fibers.

[0091] Fiber mercerization was carried out as follows: A sample of Rayfloc®-J-LD (never dried) was obtained as a 33.7% solid wet lap from the Rayonier mill at Jesup, Ga. Rayfloc®-J-LD is an untreated southern pine Kraft pulp commercially available from Rayonier Performance Fibers Division, Jesup, Ga. A 70.0 g (dry weight base) sample of Rayfloc®-J-LD was treated with an aqueous solution of 16% (w / w) sodium hydroxide at room temperature at a consistency of about 3.5%. The mixture was agitated for about 10 min; then excess NaOH was removed by suction filtration or centrifuge. The resulting mercerized pulp then was washed with excess water, neutralized to a pH of 6.4 with acetic acid solution (0.01 M) at a consistency of about 3.5%, and optionally sheeted and dried.

[0092] Handsheets of blends of fibers then were formed by thorou...

example 2

[0094] This example illustrates a method for cross-linking a blend of fibers in the sheet form prepared in the manner described above in example 1. In order to determine the effect of increasing the amount of conventional fiber on absorbent properties of fibers cross-linked in the sheet form, sheets with various proportions of Rayfloc®-J-LD and mercerized fibers were prepared as described in example 1 and used in this example. Sheets were soaked in a bath of 2% solution of glyoxylic acid (obtained as 50% solution in water commercially available from Clarinet Corporation, Charlotte, N.C.) for about 1 to 2 min and then pressed to a pick-up that affords about 2% of glyoxylic acid on fiber. Sheets then were dried and cured in one step process at 190° C. for 15 min.

[0095] The absorbent capacity, absorbency under load, centrifuge retention, knots and fine contents of the cross-linked sheets were determined. The results are summarized below in Table 1.

TABLE 1Fiber BlendMer-AbsorbencyAbs...

example 3

[0096] This example illustrates a method for cross-linking a blend of fibers in sheet form using DP-60 as a cross-linking agent (Belclene® DP-60 is a mixture of polymaleic acid terpolymer with the maleic acid monomeric unit of dominating (molecular weight of about 1000) and citric acid commercially available from BioLab Industrial Water Additives Division). Sheets with various proportions of Rayfloc®-J-LD and mercerized fibers were prepared as described above in Example 1, and then were soaked in a bath of DP-60 solution (5%) for about 1 to 2 min and then pressed to a pick-up that affords about 5% of DP-60 on fibers. Sheets were then dried and cured in a one step process at 190° C. for about 15 min.

[0097] The absorbent capacity, absorbency under load, centrifuge retention, knots and fine contents of cross-linked sheets were determined. The results are summarized in Table 2.

TABLE 2Fiber BlendAbsorbencyAbsor-KnotsMer-Under LoadbentCentrifugeandRayfloc ®-cerized(0.3 psi)Capac-Retent...

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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.

Description

FIELD OF THE INVENTION [0001] The present invention is directed to a method of making chemically cross-linked cellulosic fiber in the sheet form and to the product resulting from the process. DESCRIPTION OF RELATED ART [0002] Absorbent articles intended for personal care, such as adult incontinent pads, feminine care products, and infant diapers typically are comprised of at least a top sheet, a back sheet, an absorbent core disposed between the top sheet and back sheet, and an optional acquisition layer disposed between the top sheet and the absorbent core. The acquisition layer comprised of, for example, acquisition fibers, usually is incorporated in the absorbent articles to provide better distribution of liquid, increase the rate of liquid absorption, and reduce gel blocking. A wide variety of acquisition fibers are known in the art. Included among these are synthetic fibers, a composite of cellulosic fibers and synthetic fibers, and cross-linked cellulosic fibers. Cross-linked ...

Claims

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Application Information

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IPC IPC(8): A61F13/15A61L15/28D21C9/00
CPCA61F13/53A61F13/537A61L15/28D21C9/002C08L1/02
Inventor HAMED, OTHMAN A.CHMIELEWSKI, HARRY J.MURGUIA, TINA R.SEARS, KARL
Owner HAMED OTHMAN A
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