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Chemically Stiffened Fibers In Sheet Form

Inactive Publication Date: 2007-11-22
RAYONIER TRS HLDG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]In view of the difficulties presented by methods for making cross-linked fibers, there remains a need for a simple, commercially feasible process suitable for making cross-linked or stiffened fiber in sheet form. A need also exists for stiffened fibers in sheet form that, upon defiberizing, produce fiber having low contents of fines, and knots and nits. In add

Problems solved by technology

Despite the commercial availability and practicality, cross-linked cellulosic fibers have not been widely adopted in absorbent products, seemingly because of the difficulty of successfully cross-linking cellulosic fibers in sheet form.
More specifically, it has been found that cross-linked fiber in sheet form tends to become more difficult to defiberize without causing substantial problems with the fibers.
These problems include severe fiber breakage and increased amounts of knots and nits (hard fiber clumps).
Another short-coming is that upon wetting, the cross-linked fiber tends to emit a strong, burnt-like odor that is objectionable to most manufacturers of personal care products.
These disadvantages render cross-linked fiber unsuitable for applications in absorbent articles intended for body waste management.
Efforts to make cross-linked fibers in sheet form have met with limited success.
Unfortunately, the use of mercerized fiber to produce cross-linked fiber in sheet form is relatively expensive.

Method used

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  • Chemically Stiffened Fibers In Sheet Form
  • Chemically Stiffened Fibers In Sheet Form
  • Chemically Stiffened Fibers In Sheet Form

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0101]This example illustrates a representative method for making stiffened fibers in sheet form.

[0102]In this method a treatment composition solution containing citric acid (3.2 weight %), polymaleic acid (0.8 weight %), and a catalyst sodium hypophosphite (0.8 weight %) was prepared. The pH of the solution was adjusted to about 3.0 with an aqueous solution of NaOH (50 weight %).

[0103]The treatment composition solution then used to treat hand sheets of fluff pulp obtained from a jumbo roll of Rayfloc®-J-LD (conventional wood fluff pulp, commercially available from Rayonier, Inc., Jesup, Ga.). The hand sheets each had dimensions of 11 inches by 11 inches, a basis weight of about 680 gsm (g / m2), and density of 0.42 g / cc. Each hand sheet was dipped in the treatment composition solution and pressed to achieve the desired level of treatment composition solution (100% wet pick-up). The treated sheets were then dried and cured at about 186° C. in an air-driven laboratory oven for about 10...

example 2

[0105]This example illustrates an alternative method for making stiffened fibers in sheet form.

[0106]A 12 inch by 12 inch hand sheet of stiffened fibers with a basis weight of about 650 gsm was made in the following manner: Rayfloc®-J-LDE (65.0 g, moisture content about 7%) was dispersed in water then added to a handsheet chamber. An aqueous solution of citric acid, PMA, and sodium hypophosphite was added to the fiber suspension in the hand sheet chamber. More water was then added so that the final volume of the mixture was 10.0 L, and the mixture contained 3.2 wt % citric acid, 0.8 wt % PMA, and 0.7 wt % sodium hypophosphite. The pH of the solution was adjusted to about 3.0 by adding sodium hydroxide solution (50%). The suspended fibers in the handsheet mold were then gently agitated with a standard perforated mixing plate that was inserted into the slurry and moved up and down about 12 times, then removed. The water was then drained through the forming screen of the handsheet form...

example 3

[0109]This example illustrates a method for making acidic stiffened fiber.

[0110]In this example, the procedure described in Example 1 was followed, except that in this experiment after curing the sheet of stiffened fiber was treated with an aqueous solution of citric acid. Three sample sheets were produced, one having 1.0 weight % citric acid, a second having 1.5 weight % citric acid, and a third having 2.0 weight % citric acid, based on the to total weight of the stiffened fiber sheet.

[0111]The pH of the acidic stiffened fiber samples was measured using the following method. 10.0 g of stiffened cellulosic fiber was saturated with distilled water (50.0 g). The produced mixture was left for about 10.0 minutes, after which about 10.0 grams of liquid was squeezed out of the fiber. The pH of the squeezed liquid was measured and used as the pH of the fiber. The results are summarized in Table 2, below.

TABLE 2pH of acidic stiffened fibers prepared asshown in Example 3Acquisition fiberCitr...

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Abstract

A method for making stiffened cellulosic fiber in sheet form, and the resultant stiffened cellulosic fiber. The method of making the stiffened fibers involves impregnating a cellulosic base fiber in sheet form with a treatment composition solution, drying and curing the impregnated sheet, and thereafter adding water or an aqueous solution of odor removing agent to the cured sheet to produce a sheet of stiffened cellulosic fiber having a moisture content of at least about 6.0 weight %. When defiberized, the stiffened fiber has a low content of fines and knots and nits. The stiffened fiber also exhibits a low degree of yellowing and is substantially free of a burnt-like odor. The stiffened fiber may be used in an absorbent article, such as in a liquid acquisition layer or absorbent core of a baby diaper.

Description

BACKGROUND[0001]1. Field[0002]The embodiments relate, in general to stiffened cellulosic fibers and a process for manufacturing stiffened fibers. More particularly, the embodiments relate to a process that provides stiffened fibers in sheet form useful for making a liquid acquisition layer suitable for use in absorbent products. The stiffened fibers of the embodiments can be described as having rapid liquid absorption and acquisition, high liquid absorbent capacity, low liquid retention capacity, and low contents of fines and knots and nits. In addition, the fiber is substantially free of a burnt-like odor. The embodiments also relate to personal care products that use the stiffened fibers. The personal care products have improved acquisition and reduced rewet.[0003]2. Description of Related Art[0004]Absorbent articles intended for personal care products, such as adult incontinent pads, feminine care products, and infant diapers typically are comprised of at least a top sheet, a bac...

Claims

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Application Information

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IPC IPC(8): D04H1/00D04H13/00
CPCA61F13/53A61F13/5376A61F2013/530481A61L15/28A61L15/46A61L2300/106D04H1/70A61L2300/11A61L2300/212A61L2300/802C08L1/02D04H1/732Y10T442/697Y10T442/696
Inventor HAMED, OTHMAN A.
Owner RAYONIER TRS HLDG
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