Diaper with osmotic pressure control

Details Diaper with osmotic pressure control Diaper with osmotic pressure control

1999-07-29

2001-04-10

Ruhl, Dennis (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S385230

Reexamination Certificate

active

06215038

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to absorbent articles, particularly absorbent structures that are useful in personal care products such as disposable diapers, incontinence guards, childcare training pants, feminine hygiene products and the like. (The reference to “diapers” in the title is merely illustrative).
BACKGROUND OF THE INVENTION
Personal care products include absorbent articles like diapers, training pants, incontinence devices, feminine hygiene products and the like. These products are designed to absorb and contain body exudates and are generally single-use or disposable items which are discarded after a relatively short period of use—usually a period of hours—and are not intended to be washed and reused. Such products are placed against or in proximity to the wearer's body to absorb and contain various exudates discharged from the body. All of these products typically include a liquid permeable bodyside liner or cover, a liquid impermeable outer cover or backsheet, and an absorbent structure disposed between the bodyside liner and outer cover. The liquid impermeable outer cover may be breathable, i.e., permeable to water vapor.
It has been found that urination can occur at rates as high as 15 to 20 milliliters per second and at velocities as high as 280 centimeters per second. The volume of urine released per occurrence can vary from about a nominal amount to about 100 ml. It's important for the absorbent article to rapidly uptake liquid to avoid excessive pooling of liquid on the body-facing surface of the bodyside liner in order to avoid leakage. Even if absorbed, however, any liquid in the article contributes to the overall humidity near the wearer' skin, causing discomfort and potential skin health problems due to skin hydration.
The problem of excessive humidity near the skin in an absorbent article has been addressed in the art through a number of means. U.S. Pat. No. 5,137,525 for example, uses mechanical means to increase airflow in the article. Breathable outer covers allow air and water vapor diffusion and have been mentioned previously. Osmotic agents have been investigated for use in personal care products to a minor extent. U.S. Pat. No. 5,108,383 to Lloyd White, dated Apr. 28, 1992, for example, discusses the use of materials such as sodium chloride, sugars and other water soluble salts as osmotic promoters in diapers and the like. The agent is enclosed in a film packet or bag that is placed in the article to encourage the absorption of large quantities of liquid. White teaches that the packet, which could also include wood fluff and other absorbing materials, outer non-absorbing sheets, fasteners and the like, is placed in a composite structure designed to pick up and retain fluids. The osmotic agent does not leave the packet but encourages the flow of liquid into the packet by osmotic pressure so the packet functions like a layer of superabsorbent, absorbing large volumes of fluid.
Despite these attempts, the need exists for further improvement in the reduction of skin hydration within absorbent articles. In particular, there is a need for agents that can remove water from the skin or reduce water absorption into the skin. The present invention provides for such reduced skin hydration within an ab sorbent article. More particularly, the invention relates to absorbent articles that reduce the hydration of the skin by modifying osmotic pressure through the use of agents.
SUMMARY OF THE INVENTION
A personal care product having an osmolality changing agent incorporated into it achieves the objects of this invention. The osmolality changing agent functions by dissolving in the water (urine) released by the wearer, thus increasing the concentration of the agent in the water in the product and causing molecular water to pass outwardly through the skin cellular boundary to dilute the solution by osmotic action. The agent can reduce skin hydration significantly. Since intracellular fluid (fluid within cells) has an osmolality of about 300 milliosmoles per kilogram (mOs/kg), a solution outside of the cell, e.g., outside of the body, must have an osmolality of greater than about 300 mOs/kg in order to cause water to move from the interior of the cell to the exterior. Such a material may preferably be used in modern fiber forming processes like spunbonding and meltblowing. The reduction of skin hydration may reduce skin redness and irritation.
DEFINITIONS
“Disposable” includes being disposed of after usually a single use and not intended to be washed and reused.
“Layer” when used in the singular can have the dual meaning of a single element or a plurality of elements.
“Liquid” means a nongaseous substance and/or material that flows and can assume the interior shape of a container into which it is poured or placed.
“Liquid communication” means that liquid such as urine is able to travel from one location to another location.
“Particles” refers to any geometric form such as, but not limited to, spherical grains, cylindrical fibers or strands, or the like.
“Spunbonded fibers” refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinneret.
Such a process is disclosed in, for example, U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No. 3,542,615 to Dobo et al. The fibers may also have shapes such as those described in U.S. Pat. No. 5,277,976 to Hogle et al., U.S. Pat. No. 5,466,410 to Hills and U.S Pat. No. 5,069,970 and 5,057,368 to Largman et al., which describe fibers with unconventional shapes.
“Meltblown fibers” means fibers formed by extruding a molten thermoplastic material through a plurality of fine die capillaries as molten filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241. Meltblown fibers are microfibers which may be continuous or discontinuous, and are generally smaller than 10 microns in average diameter.
“Conjugate fibers” refers to fibers which have been formed from at least two polymers arranged in substantially constantly positioned distinct zones across the cross-section of the fibers and which extend continuously along the length of the fibers. Conjugate fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et al., U.S. Pat. No. 5,336,552 to Strack et al., and U.S. Pat. No. 5,382,400 to Pike et al.
“Biconstituent fibers” refers to fibers, which have been formed from at least two polymers extruded from the same extruder as a blend. Fibers of this general type are discussed in, for example, U.S. Pat. No. 5,108,827 to Gessner
“Bonded carded web” refers to webs that are made from staple fibers which are sent through a combing or carding unit, which separates or breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. Such fibers are usually purchased in bales, which are placed in an opener/blender, or picker, which separates the fibers prior to the carding unit. Once the web is formed, it then is bonded by one or more of several known bonding methods. One such bonding method is powder bonding, wherein a powdered adhesive is distributed through the web and then activated, usually by heating the web and adhesive with hot air. Another suitable bonding method is pattern bonding, wherein heated calender rolls or ultrasonic bonding equipment are used to bond the fibers together, usually in a localized bond pattern, though the web can be bonded across its entire surface if so desired. Another suitable and well-known bonding method, particularly when using conjugate staple fibers, is through-air bonding.
“Airlaying” is a well-known process by which a fibrous nonwoven layer can be formed. In the

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