Flushable Sanitary Napkin

Abstract

A flushable sanitary napkin having a conventional high wet-strength, non-woven cover but which can readily be torn longitudinally into two substantially equal portions to release the absorbent core from the encasing cover thereby permitting flushing away of the core and the cover separately in a conventional water closet.

Description

BACKGROUND OF THE INVENTION

This invention relates to sanitary napkins and more particularly, is directed to sanitary napkins having conventional high wet-strength, non-woven covers but which can be safely disposed of subsequent to use simply by flushing away in an ordinary water closet.

Sanitary napkins conventionally are comprised of a highly absorbent core of fibrous material, such as, comminuted wood pulp fibers, regenerated cellulose fibers, cotton linters, bleached sulfite creped wadding, and the like, encased in a high wet-strength, non-woven fabric cover which extends beyond the ends of the core to provide the usual attachment tabs. The fibers of the non-woven fabric cover are generally bonded together by adhesive binders which, to provide high wet-strength characteristics to the cover material, are generally insoluble in water. The binder system thus imparts to the cover material the necessary tensile strength and abrasion resistant properties such that it will not disintegrate in use when it is wetted with menstrual discharges.

Such sanitary napkins are, from a functional standpoint, very acceptable, but disposability thereof has been particularly annoying because they cannot be flushed away in a conventional water closet. Because of the inherent, high wet-strength characteristics of the non-woven cover material which holds together the readily water dispersible components of the absorbent core, such sanitary napkins remain too bulky when placed in an excess of water to pass through a conventional water closet and its attendant sewer system. The non-woven cover remains intact thus holding together the otherwise readily dispersible absorbent core ultimately resulting in clogging of the piping fixtures of the sewer system if the napkin is attempted to be flushed away in a water closet.

Many attempts to provide a truly flushable sanitary napkin have been proposed, most of which have been directed to the development of a cover fabric which, when placed in an excess of water, would disintegrate and permit the absorbent core contained therein to disperse and thus be safely flushed away. Since the properties required of a sanitary napkin during use, namely those of wet abrasion resistance and wet tensile strength, are sacrificed considerably with napkin covers which readily disperse in an excess of water, all known prior attempts to develop a truly flushable sanitary napkin have generally resulted in an inferior sanitary napkin from a functional standpoint. Typically, such flushable napkins have tended to fall apart in use when wetted with menstrual fluids as the cover materials lacked wet abrasion resistance.

I have now provided, for the first time, a truly flushable sanitary napkin in which the cover material has the excellent in use qualities of high wet-strength and wet abrasion resistance, yet which can be easily and safely flushed away in a conventional water closet.

SUMMARY OF THE INVENTION

According to the present invention, a flushable sanitary napkin is provided which comprises an absorbent core of biodegradable fibrous material with a non-woven, biodegradable fibrous cover surrounding the core and extending beyond the ends thereof to form attachment tabs. The fibers or yarns in the cover are oriented predominantly in the longitudinal direction relative to the napkin and the longitudinal edges of the cover are overlapped on the bottom of the core. On the bottom surface of the cover extending centrally and longitudinally from end to end thereof are a pair of spaced, parallel reinforcing strips at least one of which serves to seal together the overlapped edges of the cover. The cover is thus readily torn longitudinally into two substantially equal portions to separate the absorbent core from the cover upon the application of laterally opposed pulling forces exerted on or between the reinforcing strips at either end of the cover whereby the napkin is readily disposed of subsequent to use by flushing away the separated core and cover in a conventional water closet.

DESCRIPTION OF THE DRAWINGS

The sanitary napkin of the present invention will be even more readily understood by reference to the following detailed description when read in conjunction with the accompanying drawings in which:

FIG. 1 is an overall perspective view of the sanitary napkin as viewed from the bottom;

FIG. 2 is a cross sectional view taken approximately along lines 2--2 of FIG. 1; and

FIG. 3 illustrates the tearing of the cover into two substantially equal portions to release the absorbent core therefrom.

Referring now particularly to FIG. 1, a sanitary napkin, generally designated by the numeral 10, consists of a highly absorbent core 12 of fibrous material which can be made from comminuted wood pulp fibers, regenerated cellulosic fibers, cotton linters, bleached sulfite creped wadding, and the like or combinations thereof. The absorbent core 12 is encased in a cover 14 that extends beyond the ends of the absorbent core 12 to provide the usual attachment tabs 16. The longitudinal edges 18 and 19 of the cover 14 overlap on the bottom of the napkin (i.e., the side of the napkin which, in use, is worn away from the body).

The cover 14 is of a non-woven fabric and can be such as that generally described in U.S. Pat. No. 3,123,076 issued to H. W. Griswold on Mar. 3, 1964 and which can be made by the method and apparatus shown and described in detail and claimed in Kalwaites Pat. No. 2,862,251 issued Dec. 2, 1958 or in accordance with the teachings of Griswold Pat. No. 3,081,514 issued Mar. 19, 1963 or Griswold et al. Pat. No. 3,081,515 also issued Mar. 19, 1963. In general, such non-woven fabrics are formed of cellulosic fibers which become oriented predominantly in the machine direction and which have high wet-strength and abrasion resistance imparted thereto by using an adhesive binding material applied by printing or impregnation techniques. The binders are present in an amount ranging from about 8 percent to about 16 percent by weight based upon the weight of the completed fabric (fabric plus binder).

Also suitable for the cover 14 can be a so-called non-woven "scrim" fabric made up of cross laid yarns adhesively bonded at their points of intersection. Such scrim fabrics which are suitable as napkin covers have a higher count of yarns per inch running in the longitudinal direction than in the transverse direction relative to the absorbent core 12, such that the yarns would be said to be oriented predominantly in the longitudinal direction relative to the napkin 10.

Both types of such non-woven fabrics are ideally suited for sanitary napkin covers because of their soft hand and excellent tensile strength, particularly in the machine direction, which provides adequate pinning strength in the tabs 16 for supporting the napkin by conventional suspension devices. Further, the fiber bonding in the cover material imparts excellent wet-strength and wet abrasion resistance to the cover, which are essential for adequate in use function of sanitary napkins.

However, sanitary napkins made with such non-woven fabric covers, while being ideal from a product function standpoint, normally cannot be disposed of by flushing away in a conventional water closet, because the very properties which make the cover functionally desirable, prevent it from releasing the water dispersible absorbent core when placed in an excess of water. That is to say, the high wet-strength and wet abrasion resistance of such covers prevent it from disintegrating or opening up when flushed away in an ordinary water closet.

To solve this dilemma, the present invention provides a means whereby the user can separate the conventional and desirable sanitary napkin non-woven cover and absorbent core subsequent to use so that they can be disposed of by simply flushing away in a conventional water closet without fear of clogging the water lines attendant therewith, thus eliminating the undesirable methods of disposal required heretofore, i.e.: individually wrapping and keeping used napkins in a receptacle for latter removal with other household solids wastes.

Because the napkin cover 14 is a non-woven fabric with its fibers or yarns aligned predominantly in the longitudinal direction, it is relatively easy to tear the cover by the application of opposed pulling forces at right angles to the machine direction, i.e., in a cross-machine direction, which exhibits lower tensile strength than the machine direction of the fabric. Therefore, in the sanitary napkin of the present invention, the cover 14 is aligned with respect to the core 12 such that the machine direction of the non-woven fabric runs longitudinally of the napkin 10. Extending along the center line and also longitudinally from end to end of the cover on its bottom surface are a pair of spaced parallel reinforcing strips 20 and 22 which can be of a thermoplastic or thermosetting adhesive or a water-soluble adhesive which serve to seal the overlapping portions of the cover on the bottom surface of the napkin 10, as well as a reinforcing guide for tearing the napkin cover 14 longitudinally into two substantially equal portions in a manner described more fully hereafter. While the napkin illustrated shows both reinforcing strips 20 and 22 serving to seal the overlapped cover 14, it is apparent that the extent of cover overlap can be smaller than illustrated and that only one of the pair of reinforcing strips need be used to seal the overlap.

The reinforcing strips 20 and 22 can be applied to the cover by extrusion, printing, or spraying techniques during the manufacture of the napkin. Particularly suitable is the hot extrusion of so-called "hot-melt", thermoplastic adhesives, but any material such as a thermosetting adhesive, paraffin waxes, glue, starch, sugars, shellac, rubber, and the like, can also be used. Also suitable as reinforcing strips are threads, yarns, or tows adhesively bonded to the cover. It is also preferred that the reinforcing lines be colored to provide a visual means for identifying the side of the napkin that is to be placed away from the body during use as well as a guide for indicating where the cover tear is to be initiated when the napkin is to be flushed away subsequent to use.

The absorbent core 12 is formed of cellulosic or natural fibers or fibrous materials, rendering them biodegradable. The non-woven cover can be of cellulosic fibers or yarns bonded by biodegradable adhesives or non-biodegradable adhesives which will render them also substantially biodegradable, the non-biodegradable adhesives when used being reduced to particulate form in waste systems. Also, because the cover is of much less bulk relative to the core, it can be made of non-biodegradable fibers or be made of non-biodegradable fibers or yarns such as Nylon, polyethylene, polypropylene, polyvinyl chloride and the like, bonded by biodegradable or soluble adhesives, particularly when the cover fabric is of the non-woven "scrim" type. All such covers of non-woven fiber-yarn-binder systems in combination with biodegradable fibrous cores, are substantially totally digested in municipal sewage treatment facilities or in individual septic systems leaving essentially no solids residues other than very minor amounts of fine particulate matter if non-biodegradable adhesive binders have been used in the covers.

Because the cover 14 can be removed from the core 12, and flushed away separately therefrom, the bulk of the napkin 10 is readily dispersed since the core is essentially an incoherent mass of fibers and fibrous components. The cover functions to hold the core together when the napkin is in use, but if the cover is removed the core readily breaks up and disintegrates, particularly in an excess of water. Broken up, the napkin will not clog or pack up in the convolutions and traps of a conventional water closet and its attendant plumbing such that it can be flushed away with complete safety.

In tearing the cover 14 away from the absorbent core 12 subsequent to napkin use, it is desirable that handling of the napkin in the portions wetted with menstrual fluids be avoided. To accomplish this, it is essential that the napkin cover 14 be torn longitudinally into two substantially equal portions so that the core 12 will be released therefrom without requiring handling of the core to remove it from any portion of the cover. If the cover 14 is not torn substantially along the centerline thereof, the core 12 will tend to remain lodged in the portion of the napkin cover which most surrounds the pad, requiring the user to physically remove it, a distasteful task.

Thus, the reinforcing strips 20 and 22 are positioned relatively close together on the bottom of the napkin 10, spaced an equal distance from the centerline thereof. They extend longitudinally (in the same direction as the predominant fiber or yarn orientation of the cover) from end to end, thus defining at either tab end of the napkin, a point for initiating the longitudinal tear 24 (see FIG. 3) for separating the cover 14 into two substantially equal portions. The user need only handle the napkin at either tab end as she normally does and can completely separate the cover 14 into two substantially equal portions by applying laterally opposed pulling forces exerted on or between the reinforcing strips 20 and 22 at either tab end. Because the fiber or yarn orientation of the cover fabric is predominantly in the longitudinal direction relative to the napkin, the tear 24 between the reinforcing strips 20 and 22 will tend to be in a straight line lengthwise of the napkin. Even if, however, the tear 24 tends to migrate laterally, the reinforcing strips 20 and 22 will serve to contain it substantially along the centerline of the napkin 10, thus assuring that the cover 14 will be torn into two sub-stantially equal portions allowing the core 12 to fall away free of the cover 14 by gravity alone. The core 12 escapes from the cover 14 into the bowl of a water closet where it readily disperses and then the two portions of the cover separated therefrom are also dropped into the bowl to be safely flushed away together.

Having thus particularly described the present invention with respect to a preferred embodiment thereof, it is apparent that many changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

What is claimed is:

1. In a flushable sanitary napkin having,

a. an absorbent core of biodegradable fibrous material;

b. a non-woven biodegradable fibrous covering surrounding said core and extending beyond the ends thereof to form attachment tabs; and

c. the longitudinal edges of said cover overlapped on the bottom of said core,

the improvement which comprises:

l. having the fibers in said cover oriented predominantly in the longitudinal direction relative to said napkin; and

2. providing a pair of relatively closely spaced parallel reinforcing strips on the bottom surface of said cover, extending along the longitudinal center line of said bottom surface from end to end thereof and having only one of said reinforcing strips serve to seal together the overlapped edges of said cover,

whereby a tear, commencing between said reinforcing strips at the end portions of said cover, will be contained between said strips when propagated longitudinally across the bottom of said cover by the application of laterally opposed pulling forces exerted on or between said reinforcing strips and will divide said cover into two substantially equal portions to discharge said core.

2. A flushable sanitary napkin according to claim 1 wherein said reinforcing strips are made from a hot melt thermoplastic adhesive.

3. A flushable sanitary napkin according to claim 1 wherein said reinforcing strips are made of a material selected from the group consisting of thermosetting adhesives, paraffin waxes, glue, starch, sugars, shellac and rubber.

4. A flushable sanitary napkin according to claim 1 wherein said reinforcing strips consist of threads, yarns or tows of cellulosic or non-cellulosic materials adhesively bonded to the bottom surface of said cover.

5. A flushable sanitary napkin according to claim 1 wherein said reinforcing strips are spaced an equal distance from the center line of said napkin.

6. A flushable sanitary napkin according to claim 1 wherein said reinforcing strips contrast in color to the color of said cover to indicate the side of the napkin to be worn away from the body and to provide visual indicia for initiating the tear in the cover at the tab end subsequent to use.