Method of making a multi-layer absorbent article

Details Method of making a multi-layer absorbent article Method of making a multi-layer absorbent article

1999-06-10

2001-01-23

Ruhl, Dennis (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S385010, C604S385180

Reexamination Certificate

active

06177606

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to articles for absorption of bodily fluids, e.g., menstrual tampons and articles for urine collection and absorption of wound exudate.
Many requirements are imposed on absorbent articles used to absorb bodily fluids. For example, it is often desired that such articles maintain substantially their original dimensions after absorption of fluid, that the fluid be retained by the device during movement of or pressure on the device, that the device not leak during use, and that the device be comfortable to the user.
In the case of menstrual tampons, tampons may be uncomfortable to remove if they swell excessively, should not leak during active use and should fit comfortably while also resisting leakage past the tampon.
SUMMARY OF THE INVENTION
The invention features improved absorbent articles, e.g., menstrual tampons. Absorbent articles made according to the invention resist swelling during use, with preferred articles maintaining substantially their initial dimensions after absorption of fluid during use. When used as tampons, the articles exhibit good resistance to leakage, substantially uniform surface wetting, and good resistance to exudation of fluid from the device during use.
In one aspect, the invention features an absorbent article including a resilient ring containing an absorbent material, and a central portion spanning the ring. The resilient ring is dimensioned to be positioned around a user's cervix, and, when the absorbent article is in position, the central portion is positioned below the user's cervix, e.g., to intercept menstrual fluid as it exits the cervix if the article is a tampon, and the resilient ring forms a gasket against the user's pericervical tissue to prevent leakage past the tampon. This positioning increases the likelihood that menstrual fluid will contact the article, by placing the article at the site of egress of the fluid. Moreover, because the absorbent material is contained within the ring, a wide variety of absorbent materials can be used, without the need for the absorbent material to have structural integrity or be suitable for contact with the vagina (requirements imposed on absorbent materials used in conventional tampons).
In another aspect, the invention features an absorbent article for absorption of bodily fluids, e.g., a tampon, including (a) a layer of non-absorbent material defining a tunnel shaped loop and a central portion enclosed by the loop (b) an absorbent material retained within the tunnel shaped loop (c) one or more apertures extending through said non-absorbent material, through which fluid can flow to reach the absorbent material; and (d) a wettable overwrap material overlying the non-absorbent material, constructed to transport fluid away from the site at which it contacts the overwrap material.
Preferably, the loop is a ring dimensioned to form a gasket between the cervix and the back wall of the vagina of a user of the tampon; more preferably, the ring has a diameter of from 1.5 to 2.5 inches. It is also preferred that the tampon be symmetrical about a plane that horizontally bisects that ring, and that the tampon be capable of functioning regardless of which side of the tampon, relative to this plane, is positioned closest to the user's cervix. This feature enables the tampon to be easily inserted, without requiring the user to determine which side should be positioned closest to the cervix. Preferred embodiments may also include one or more of the following features: The tunnel is substantially oval in radial cross-section. The oval has a major axis of from 0.5 to 1.0 inches. The central portion is substantially flat. The central portion defines an opening that is covered by the overwrap material in a manner to prevent flow of fluid through the opening and to transport fluid contacting the portion of the overwrap covering the opening outward to the absorbent material. The non-absorbent material is substantially impermeable. The apertures are positioned at approximately 11 O'clock, 1 O'clock, 3 O'clock, 5 O'clock and 7 O'clock, viewing the ring as a clock face and defining the withdrawal cord as “6 O'clock”. Alternatively, the apertures may be positioned to provide hinge points about which the loop and the enclosed central portion can be folded to collapse the absorbent article for insertion into a body cavity. The open space defined by the apertures is sufficient to enable fluid to flow into the absorbent material at a desired flow rate when the absorbent article is in use. The absorbent article includes from 1 to 1000 apertures. The non-absorbent material is an ethylene vinyl acetate foam. The non-absorbent material is perforated or is a discontinuous film. The absorbent material includes cotton, rayon, fluff pulp, and blends thereof. The absorbent material is a cotton/rayon blend. The absorbent material may include a superabsorbent material. The absorbent material includes a material that forms a gel upon contact with moisture, e.g., sodium carboxy methyl cellulose.
In another aspect, the invention features a menstrual tampon system including: (a) a tampon including a material defining a tunnel shaped loop and central portion, an absorbent material retained within the tunnel shaped loop a plurality of apertures extending through the non-absorbent material, through which fluid can flow to reach the absorbent material, and an overwrap material overlying the surface of the non-absorbent material to transport fluid over the surface of the non-absorbent material; and (b) an applicator for inserting the tampon into a body cavity, including: a holder tube constructed to hold the tampon prior to insertion, and a plunger tube, telescopically retained by the holder tube and constructed to, when inserted further into the holder tube, expel the tampon from the holder tube into the body cavity.
Preferred embodiments of this aspect of the invention include one or more of the following steps. The holder tube and the plunger tube are curved. The holder tube and the plunger tube define a radius of curvature of from about 2″ to 8″.
The invention also features methods of making an absorbent article, including (a) surrounding an absorbent material with a resilient, impermeable covering so that the covering defines a tunnel-shaped loop and the absorbent material is sealed within the tunnel, and (b) providing a web spanning the loop defined by the covering.
A preferred method includes (a) forming a first channel in a first portion of a formable material, the channel being constructed to define a closed loop, (b) providing a plurality of apertures in the formable material, in fluid communication with the channel, (c) placing an absorbent material in the channel, (d) forming a second channel, having dimensions substantially identical to those of the first channel, in a second portion of formable material, (e) aligning the first and second portions of formed material so that the corresponding channels in the first and second portions define a closed tunnel, (f) sealing the first and second portions together around the outer periphery of the closed loop, and (g) providing an overwrap material covering the outer surface of the tampon.
This aspect of the invention preferably includes one or more of the following features. The formable material includes a sheet of thermoplastic polymer and the forming steps comprise thermoforming the polymer. The formable material includes a moldable polymer and the forming steps comprise molding said polymer. The moldable polymer includes a curable material and the forming steps comprise introducing said curable material to a mold and allowing the curable material to cure. The curable material is a room temperature vulcanizable elastomer or a room temperature curable polymer. The first and second portions of formable material are sealed together by heat sealing. The method further includes laminating the overwrap to the formable material, preferably during or prior to the forming steps.

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