United States Patent 3651809

An absorption device such as a sanitary napkin is provided with a fluid impervious baffle that may be disposed of in conventional sanitary systems. The baffle comprises a thin film of a water-sensitive material which includes a water-repellent coating on that surface of the film which comes in contact with absorbed fluid in the napkin during use.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
604/368, 604/372, 604/381, D24/125
International Classes:
A61F13/15; (IPC1-7): A61F13/16
Field of Search:
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US Patent References:
3111948Absorbent pad and wrapper therefor1963-11-26Burgeni
3078849Absorbent product1963-02-26Morse
3067746Manufacture of cellulosic products1962-12-11Bletzinger et al.
2896627Sanitary napkin1959-07-28Harwood
1843037Sanitary napkin1932-01-26Mathey
1702530Absorbent pad1929-02-19Williams

Primary Examiner:
Rosenbaum, Charles F.
I claim as my invention

1. An absorptive device comprising the combination of an absorbent pad, a fluid pervious wrapper enclosing the pad and a baffle positioned adjacent the main absorbent portion of the pad, said baffle comprising a thin flexible film of a water-soluble material having a substantially continuous water-repellent coating on the surface of the film adjacent the main absorbent portion of the pad.

2. The device of claim 1 wherein the absorptive device is a catamenial napkin.

3. The device of claim 2 wherein the water-soluble material is polyvinyl alcohol and the water-repellent coating is linseed oil.

4. The device of claim 2 which includes baffles positioned at the sides of the pad, the baffles comprising a thin film of a water-soluble material having a water-repellent coating on the surface of the film adjacent the pad.

5. The device of claim 1 wherein the film has a thickness of up to about 2.0 mils.

6. The device of claim 1 wherein the baffle is located adjacent the bottom of the wrapper.

7. The device of claim 1 wherein the baffle has a thin absorbent layer disposed adjacent its uncoated surface.

8. The device of claim 1 wherein said fluid pervious wrapper is disintegratable in the presence of excess water.

9. The absorptive device of claim 1 wherein the film is capable of dissolving in an excess of water and the coating is sufficiently thick to be moisture proof in use and disintegrates when the film is placed in an excess of water.

This invention relates to absorptive devices and, more particularly, to absorptive devices such as sanitary napkins, diapers and other sanitary protection products which include a fluid impermeable baffle which is also flushable.

Sanitary or catamenial napkins generally comprise an absorbent pad which is customarily enclosed in a fluid pervious wrapper, and which has disposed in its structure a fluid impermeable baffle of thin plastic film such as polyethylene or the like.

The purpose of the fluid impervious baffle is to inhibit strike-through of absorbed fluids and to aid in spreading the exudate laterally and transversely within the napkin body. In addition, side strips, also fluid impervious, are often utilized to inhibit inadvertent side-staining caused by migration of exudate to the side edges of the pad.

A literal myriad of materials have been used for such barriers or baffles, including waxed creped wadding, sized wadding and plastic films such as polyethylene. While waxed and sized materials work well in most cases, they are not completely impervious to the passage of menstrual fluid and occasionally permit strike-through. Plastic films have adequately served the purpose of preventing exudate strike-through but are not biodegradable and thus may eventually cause problems when disposed of in toilet systems. Conventional pads are often disposed of by first stripping the fluid pervious cover from the absorbent pad element and discarding the cover separately before depositing the absorbent element in the toilet. Baffles used in such pads are usually small and flexible enough so that they will ordinarily pass through a conventional toilet system without difficulty. However, since these baffles are not biodegradable; they can hang up on screens and other elements in the sewerage systems, or build up in septic tanks to present cleaning problems.

The problem is more pressing with the recent development of water-dispersible napkin wrappers intended to make the entire unit flushable. This results in a greater number of disposals in toilets. It is highly desirable therefore to include a water-dispersible baffle in the napkin structure. In this connection, U.S. Pat. No. 3,078,849 to Morse discloses the use of a barrier that is placed in the center of the napkin which is initially liquid repellent, but subsequently, upon absorption of liquid, solubilizes in the liquid to allow liquid penetration to the absorbent layers below. The object is to provide such a napkin with a temporary liquid-repellent barrier so that the entire absorbent component of the napkin may be utilized more fully. However, while this is desirable for napkins of the structure defined in that patent, it should be apparent that exudate strike-through can occur since the barrier is only temporary.

It is accordingly an object of the present invention to provide an absorptive device with an improved baffle which is sufficiently water insoluble to prevent strike-through of absorbed fluids in use but which will dissolve when flushed in a conventional sanitary system. Another object is to provide a sanitary napkin in which all the elements are water-dispersible, including the baffle. A more specific object is to provide a sanitary napkin having the hereinbefore described characteristics.

Other objects having advantages of the invention will be understood by reference to the following specification and accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of the present invention and is partially broken away to illustrate the inner components of the sanitary napkin;

FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG. 1 and further illustrating the positioning of the bottom and side baffles with respect to the other components of the sanitary napkin;

FIG. 3 is a cross-sectional view similar to FIG. 2 and illustrating an embodiment including only a bottom baffle;

FIG. 4 is a cross-sectional view and illustrating the novel baffle of the present invention; and

FIG. 5 is a cross-sectional view similar to FIG. 2 and showing an embodiment wherein the baffle is placed between a primary absorbent pad and a secondary absorbent pad.

While the invention will be described in connection with certain preferred embodiments, it should be understood that this invention is not intended to be limited to the particular embodiments disclosed, but, on the contrary, it is intended to cover the various modifications and equivalent arrangements included within the spirit and scope of the invention. For example, while the invention has been described in connection with an absorptive device such as a sanitary napkin, it should be appreciated that the invention is equally applicable to use in connection with a diaper or other sanitary protection device.

Turning to the figures, FIGS. 1 and 2 illustrate an exemplary embodiment of a sanitary napkin with the improved baffle of the present invention. Briefly, there is shown a sanitary napkin 10, including a central absorbent pad 12, a fluid pervious wrapper 14 enclosing the pad and a bottom baffle 16 and side strips or baffles 18, 18'. The construction of the baffles in accordance with the present invention will hereinafter be described in greater detail.

Describing the illustrative embodiment in greater detail, the absorbent pad 12 and its construction are not critical. Many suitable constructions are well known. As an example, the absorptive pad can suitably comprise multiple plies of cellulose wadding, wood pulp fluff, cotton fiber batts, absorbent sponges such as regenerated cellulose, each alone or in combination with the others and with various types of synthetic fibers.

With respect to the fluid pervious wrapper 14, any conventionally known wrapper may be employed. However, the present invention is more advantageously employed in connection with a flushable wrapper, in which the elements are sufficiently water-sensitive to break up into small particles or fibers after disposal in the excess water in a toilet system. A non-woven web of textile type, staple fibers bonded with a water-sensitive adhesive such as polyvinyl alcohol, methyl cellulose, cellulose clycolate, polyvinyl methylether and the like has been found useful for the purpose. Another type of flushable wrapper is disclosed in the George et al. U.S. Pat. No. 3,407,814.

In the illustrative embodiment, the sanitary napkin 10 is provided with full tabs at 20, 20' that may be attached to a suspension device and provide support for the napkin. The wrapper 14 is desirably provided with overlapping edges 22, 22' that are bonded together by adhesive coated threads, adhesive filaments or hot melts and the like.

In accordance with the present invention, a baffle is provided which serves as a permanent fluid impenetrable barrier during use but which dissolves in excess of water so that it is "flushable" . To this end, a thin film of a water-soluble material is provided with a water-repellent coating on the surface which is disposed adjacent the main absorbent pad in the sanitary napkin structure.

Thus, as is shown in FIG. 4, the baffle comprises a thin film 17 of a water-soluble material and has a water-repellent coating 19 on one surface. Desirably, the film has a thickness of less than about 2 mil, and preferably about 1.5 mil or less. The coating provides a thin substantially continuous layer on the outer surface of one side of the baffle and desirably will be not more than about 20% of the weight of the film. Another way to define the coating is that it should be thick enough to be moisture proof in use, but thin enough to disintegrate quickly when the water-soluble substrate dissolves.

For the latter, it is preferred to employ a polyvinyl alcohol film having a thickness of about 1.5 mil, with a substantially continuous coating of linseed oil on the surface of the film. This combination optimizes the desirable characteristics of the baffle. However, other water-repellent materials such as various silicones, white oils and wax may also be employed.

A suitable polyvinyl alcohol is one having a percent hydrolysis in the range of about 79 to 98 and a viscosity (4 percent water solution at 20° C) of from about 21 to 28 cps. However, other water-soluble film forming materials such as methyl cellulose, hydroxyalkyl ether cellulose, carboxymethyl cellulose and the like may be employed.

Referring again to the drawings, FIG. 3 illustrates an embodiment utilizing only a bottom baffle. As shown, the baffle 16' is located adjacent the outer side of the pad 12'. The water-repellent coating on baffle 10' is on the side of the baffle that is adjacent to pad 12'.

FIG. 5 shows an embodiment wherein a baffle 16" is positioned between a primary absorbent pad 12" and a secondary absorbent pad 13. This secondary absorbent pad remains dry in use and functions to help maintain the original shape of the primary pad when it becomes soft or soggy after being wetted near saturation.

Thus, as has been seen, the present invention provides an absorptive device with an improved baffle which functions, in use, to prevent strike-through of absorbed fluids but which is capable of dissolving when flushed in a conventional sanitary system. This allows a sanitary napkin in which all the elements are water-dispersible.