US3294091A - Sanitary napkin - Google Patents

Description

Dec. 27, 1966 El. A. MORSE ZLZMWQ SANITARY NAPKIN Filed Jam 28, 1965 5 Sheets-Sheet l l ,477" @MEV WBC. 27, g@ E, A, MORSE SQV SANITARY NAPKIN Filed Jan. 28. 1965 5 Sheets-Shee't 2 BY @mzm/ A 7 TOR/VE Y Dec. 27, T966 E. A. MORSE BMSQ SANITARY NAPKIN Filed Jan. 28. 1965 5 Shasta-Sheet 5 United States Patent flice 3,294,09i Patented Dec. 27, 1966 3,294,091 SANHTARY NAPKIN Edward A. Morse, Fanwood, NJ., assignor to Johnson @t Johnson, a corporation of New Jersey Filed Jan. 28, i965, Ser. No. 428,673 Z Claims. (Cl. 1128-290) rhis application is a oontinuation-in-part of my co- :pending application Serial No. 237,676, filed November 14, 1962 and now abandoned.

This invention relates to santiary napkins and more particularly to improvements -in sanitary napkins having liquid-repellent components which are so associated with other napkin components to i-mpart rigidity and form stability to the napkin and to improve the fluid absorbency and fluid retentivity characteristics of the napkin.

Liquid-repellent components have been included in sanitary napkins to obtain more effective distribution of the menstrual fluid absorbed by the napkin and to prevent t-he liuid from striking through the bottom of the napkin. One type of liquid-repellent component which has been used consists of one or more sheets or films of a plastic mate-rial, such as a polyethylene film, positioned in the absorbent core portion of the napkin. Liquid-repellent components of this type have been reasonably effective in preventing the strike through of fluid through the napkin and in aiding in the distribution of the fluid t-hrough the absorbent core portion of the napkin so that its absorbing capacity may be Imore effec-tively utilized. The liquid-repellent component vmay be positioned on or adjacent to the bottom of the absorbent core portion of the napkin to provide ya .so-called one-way napkin. A napkin of this 4type Inlay be used only in one way with the side of the napkin covered with the plastic film positioned away from the body. This invention relates to such napkins.

Plastic films, such las films of polyethylene, are especial- 'ly suitable as such barriers because they are essentially impermeable to liquids. However, due to their smooth surf-ace characteristics, such films are slippery and tend to shift out of position in the napkin and thus may fail to fully perform the function for which they were included. The tendency to shift is increased when the napkin is wet with menstrual fluid which lubricates the surface of the lm. In addition, such plastic films, when subjected to crinkling or folding, tend to be noisy. When la sanitary napkin containing such a film is worn, the napkin is subjected to numerous and varied distorting forces which often Iresult in noise. Further, these films of plastic material do not impart any significant structural integrity to the napkin, but instead may distract from such integrity particularly when they are used in conjunction with napkins having an absorbent core portion consisting mostly of comminuted cellulosic pulp type material of yrelatively low density, such as relatively weak bats of wood pulp or fluff. Due to their slippery charactefristics, the films permit such pulp or fluff particles making up the bats on each side thereof in the absorbent core portion of the napkin to slide and move with respect to each other and thus become displaced from their intended and desired positions within the napkin. Furthermore, such movement of the relatively weak, low-density bats of pulp or fluff disrupts the relatively weak bonds between particles whereby the bats `lose their form stability and break down.

In that foam of sanitary napkin where the film is placed on the bottom of the absorbent core portion of the napkin directly underneath the cover which customarily encloses the absorbent core portion and extends beyond the ends thereof to provide attachment tabs, i.e., the so-called oneway napkin, thereis the further disadvantage lof the film forming a channel along which fluid absorbed by the napkin may flow, particularly when excessive amounts of fluid are absorbed by the napkin over a short period of time. A typical sanitary napkin is generally in the form of a flat elongated, rectangular shaped body, about eight inches long and :about two and one-half inches wide. When a napkin of this configuration is worn, it tends to assume an inverted U-shaped configuration in transverse section, and particularly, is such true when the absorbent core lportion consists mostly of cellulosic pulp or fluff materials. This configuration is not desired and it is preferred that the napkin maintain yits flat conguration so that the napkin will be retained 1n intimate contact with t-he body. As a consequence of this distortion, the film covering the bottom of the absorbent core portion of the napkin tends to sag and become displaced from the bottom surface, thereby creating a v-oid or air space in the form of a channel which extends in the direction of the length of the napkin. When absorbed fluid penetrates the absorbent core portion of the napkin through to the film, the fluid tends to flow in the direction of the channel formed by the displaced lm, instead of being laterally distributed as intended along the film to other portions of the absorbent core not saturated by the fluid. As a consequence, the fluid may strike through the ends of the napkin causing failure.

I have discovered that a sanitary napkin with an absorbent core consisting mostly of cellulosic pulp or fluff materials Iand which uses such films can be provided by compressing the pulp or fluff material forming the absorbent core to a certain density and by using a film `which is of sufficient size to cover most of the bottom and sides of the absorbent core portion of the napkin and which is also bonded to the bottom and sides of the absorbent core. In this manner, I obtain a -sanitary napkin having an absorbent core consisting mostly of pulp or fluff material which not only provides an effective barrier to the passage of fluid through the napkin, but which is also essentially noiseless when worn, which has form and structural stability, 4and which eliminates the problem of channeled flow at the bottom of the napkin to t-he ends thereof. Other features of my invention include adhesively associating the cover portion of the napkin with the absorbent core portion in such a manner as to impart additional form and structural stability to the napkin. The napkin of my invention, due to its construction, effectively -prevents the fluid from passing beyond the side edges of the napkin, thereby eliminating side spread failure. The napkin of ymy invention also ibas the additional feature of tending to resist distortion, particularly in a transverse direction, when worn.

Reference is made to the accompanying drawings wherein various embodiments of the invention are illustrated by way of example.

In the drawings:

FIG. l is a perspective view of a napkin incorporating my invention, partially cut away -to reveal its inner construction.

FIG. 2 is a view of the napkin of FIG. 1 in an inverted position.

FIG. 3 is a view of the plastic lm incorporated into the napkin of- FIGS. 1 and 2 and having spaced areas of adhesive on one surface.

FIG. 4 is a view of FIG. l taken along lines 4 4.

FIG. 5 is a perspective view of another embodiment of the invention.

FIG. 6 is a View of the napkin of FIG. 5 in an inverted position.

FIG. 7 is a perspective View of the plastic film incorporated in the napkin illustrated in FIGS. 5 and 6 and provided with spaced areas of adhesive.

FIG. 8 is a view of FIG. 5 taken along lines 8-8.

FIG. 9 is a perspective view of another embodiment of the invention.

FIG. 10 is a view of the napkin of FIG. 9 in an inverted position.

FIG. 11 is a perspective view of the plastic film incorporated in the napkin illustrated in FIGS. 9 and 10 and provided with spaced areas of adhesive, and

FIG. l2 is a view of FIG. 9 taken along lines 12-12.

One form of napkin 10 incorporating the invention is illustrated in FIGS. 1-4 and includes a relatively thick, elongated absorbent core 12 enclosed within a' liquid pervious wrapper 14 whose ends extend beyond the ends of the absorbent core to provide the usual attachment tabs 16. The absorbent core may be about two and one-half inches wide and eight inches long and consists of a bottom layer 18 of comminuted wood pulp fibers weighing about 50 grains (14 grains per cubic inch), a sheet of semirepellent bleached, sulfite creped paper 20 which Weighs about pounds per ream, three plies 22 of absorbent bleached, sulfite paper wadding weighing about 9 pounds per ream and a top layer 24 of comminu-ted wood pulp fibers weighing about 50 grains (14 grains per cubic inch). The entire assembly is enclosed within the liquid pervious wrapper 14.

A thin flexible film 28 of polyethylene, approximately one mil thick, is positioned intermediate the liquid pervious wrapper 14 and pulp or fluff layer 18 and covers the bottom and sides of the absorbent core. The top surface 30 of the absorbent core, which is not covered by the film, is the surface which is placed against the body when the napkin is worn to absorb fluid which impinges upon it.

As seen in the drawings, the absorbent core consists almost entirely of comminuted pulp or fluff, layers 18 and 24, with the exception of plies 22 of paper wadding positioned centrally Within the core. Normally, bats of pulp or fluff lack such form and structural stability that they can not be used in sanitary napkins and other absorbent products without being stabilized by bonding agents or by other elements positioned adjacent to successive layers of relatively thin pulp bats. Stabilization by bonding agents impregnated into the bats so far have yielded pads of reduced adsorbency when compared to an equal amount of unstabilized pulp mass. Use of additional fibrous elements adjacent to the pulp bats for stabilization similarly reduced the over-all absorbency of the napkins in addition to considerably increasing the cost which necessarily had to be passed on to the consumer.

Because cellulosic pulp or fluff is relatively inexpensive, and particularly because of its excellent absorbency, it is desirable that as much of the total product be made therefrom as possible. I have found that highly absorbent sanitary napkins, the absorbent cores of which consist almost entirely of comminuted cellulosic pulp or fiuff, can be made in the manner described more fully hereafter so as to have excellent form and structural stability, both during the manufacture thereof and in use.

It is essential, that the cellulosic pulp bats used to form the absorbent core in the sanitary napkins of this invention be subjected to slight compression. Since cellulosic pulp fibers are extremely short, a thick bat formed therefrom does not have the ooherency, integrity or structural stability of a similar bat formed of cotton or other long staple fibers. I have found that by compressing the cellulosic pulp bats used to form the core to a density of at least about 14 grains per cubic inch and preferably to a density of from about 14 to about 24 grains per cubic inch, form and structural stability can be imparted to the core. However, I have also found that a core of such pulp fibers so compressed expands and tends to spring back to its size before compression whereupon it loses the form and structural stability obtained by compression. By so bonding the film to the bott-om and sides of the core, as more fully described hereafter, the core is restrained from expanding and the desired density, form and structural stability are maintained.

The plastic film 28 is adhesively bonded to the bottom surface of the fiuff layer 18 of the absorbent core by applying an adhesive, such as that available from Rohm & Haas under their product designation HAS, along two spaced lines 32 to the inner surface of the film before the remaining components of the absorbent core are placed thereon. By so applying the adhesive to the film, the portion of the film covering the bottom surface of fluff layer 18 of the absorbent core becomes adhesively bonded thereto, and is maintained in fixed intimate contact therewith. The portions of the film covering the sides of the absorbent core are also adhesively bonded in position. This can be achieved by applying adhesive to the portions 34 of the film which cover the sides of the core at the same time the adhesive is applied to the portion of the film covering the bottom surface of the core. Thus, the film is securely bonded to the bottom and side edges of the absorbent core. Other bonding patterns can be used o1' the film can be over-all bonded to the core.

T-he advantages of so securing the film to the prdominantly flu core are numerous. First, shifting of the film with respect to the absorbent core and shifting of other components in the core are eliminated, both as the napkin is being manufactured and during use. Second, since the film is securely associated withthe absorbent core, deformation of the normally easily deformable core into an inverted U-shaped configuration when the napkin is worn is resisted and the core tends to retain its desired fiat configuration. Third, adhesively securing t-he portion of the film covering the side edges of the core prevents the film from sliding down and away from the sides of the core which would result in side sprad failure of the napkin. Fourth, adhesively bonding the film to the core reduces lthe noise characteristics of the film which are more pronounced when the film is unattached to the core and is free to move from contacting relationship therewith.

Two other major desirable characteristics are obtained in the foregoing construction. As noted above, the function of the film is to act as a barrier to the penetration of fiuid through the absorbent core. If t-he napkin is subjected to a considerable quantity of impinged menstrual fluid over a short period of time, the fiuid tends to quickly strike through the absorbing components of the core into contact with the film and form a pool of fluid. If the film were not maintained in intimate contact with the absorbent surface of the core, the film would not effectively transmit the fiuid which impinges -upon it laterally of the absorbent core to other portions of the core not yet wetted by the fluid. Instead, the film would tend to form a lengthwise valley or channel along which the vfluid would tend to fiow towards the ends of the napkins. Bonding the film to the bottom surface of the core eliminates this problem. In addition, the entire napkin structure is integrated and possesses a form stability not obtainable if the film is not so bonded. The respective components of the absorbent core are retained in relatively fixed relationship with respect to each other so that they may fully exercise their intended functions.

Another embodiment of the invention is illustrated in FIGS. 5-8. In this form, the sanitary napkin 36 includes an elongated absorbent core 38 about one-half inch thick and consisting entirely of comminuted wood pulp, socalled fluff, or similar short cellulosic fibers. As d'escribed above with respect to the embodiment shown in FIG. 1 through FIG. 4, attempts to provide napkins with a core of such fibers were unsuccessful in that they lacked form and structural stability, had no shape retention, collapsed easily and were easily deformed and distorted when used, particularly when the became wet with menstrual fiuid. This is due to the inherent short fiber characteristic of a bat of wood pulp fibers. However, by conipressing the bat of short, cellulosic 'pulp fibers, either when dry or in the presence of a small amount of moisture, to a densisty of at least 14 grains per cubic inch and preferably to a density of from about 14 to about 24 grains per cubic inch, form and structural stability are imparted to the core and maintained therein by the adhesively adjoined plastic film. v

"The other components of the napkin `are the plastic film 40'and the cover 42 which encloses the film'and the absorbent core. As in the preceding embodimentVthe plastic film covers the bottom and side edges of the absorbent core and is adhesively bonded to the bottom and side edges. In thisv form', the adhesive is applied to the central portion of plastic film in a broad band 44, instead of along the spaced lines as in the` preceding embodiment. Nevertheless, spaced lines vof adhe-sive, o'r 'over-all coatings of adhesive can be used in this embodiment as wel-l asin the preceding embodiment.- K

The form and struct-ural stability of the nap-kin, and particularly the napkin Iillustrated in FIGS. 5-8 canV be further enhanced by adhesively bonding the cover to the plastic film and thereby to the absorbent core portion, thus vstabilizing the absorbent core portion with respect to the cover. This can be achieved by applying a line of adhesive 46 to the longitudinal side edges of the cover which are arranged in overlapping relationship with respect to ea-ch other. The overlapped edges of the cover are positioned on the bottom surface of the absorbent core, i.e., that surface which is covered with the plastic film. By using a liquid adhesive applied to the overlapped edges ofthe cover, and by using sufficient adhesive,

some of the adhesive will Icontact the portion of the filml adjacent to the overlapped edges, and adhesively bond the overlapped edges of the cover and the film together.

A plastic film of polyethylene approximately threequarters of a mil to one mil thick is preferred as the barrier. However, films of other thicknesses and other plastic films, s-uch as lfilms of polyvinyl chloride, polypropylene and the like can 'be used. In the preferred form of the invention, the film is -desirably colored, i.e., pink or blue, to indicate to the user of the napkin that the side of the napkin covered by the film is to be placed away from the body when the nap-kin is worn.

Still another embodiment of the invention is illustrated in FIGS. 9-12. Here, the sanitary napkin 50 includes an absorbent core 52 also consisting entirely of comminuted cellulosic pulp or fluff fibers as in the immediately foregoing example. Accordingly, the core 52 of pulp fibers must be made rfrom a bat of such fibers which has been compressed to a density of at least 14 grains per cubic inch and preferably to a density of from about 14 to about 24 grains per cubic inch to impart vform and structural stability thereto. l

The principal differences between the embodiment of FIGS. 9-12 and that of FIGS. 5-8 relate to the Huid pervious cover 54 and its relationship to the plastic film 56 and to the cellulosic pulp core 52, and the relationship of the plastic film 56 to the fluid pervious cover 54 in the area extending into the attachment tabs 58 beyond tle ends of the core 52.

In this embodiment, the plastic film covers the bottom of the absorbent core and is adhesively bonded thereto by spaced patterns of adhesive or by over-all bonding if desired. However, it is seen that the cover 54 does not entirely surround the absorbent core and the plastic film adhered thereto, but instead the longitudinal side edges of the cover terminate short of overlapping relationship. It is preferred that the side edges of the cover extend only partially down the side edges of the absorbent core as shown in FIG. l2, and that the portion of the cover overlying the side edges of the core be positioned between the core and the plastic film.

The plastic film 5o is, as in the preceding embodiments, als-o adhered to the core portion by applying a line of adhesive 60 along the longitudinal side edges of the film.

After the cover is positioned over the core, with its longitudinal marginal portions overlying the sides of the core, the side edges of the plastic film to which adhesive lines have been applied, are folded upwardly and pressed against the core. A sutiicient amount of adhesive is used such that it penetrates the cover intermediate the core and the plastic film, thereby bonding each component, one to the other.

It is further seen that the plastic fil-m 56 extends beyond the ends of the absorbent core and is adhesively bonded to the overlying cover portion `forming the attachment tabs 5'8. In this portion of the napkin 5t), the longitudinal lmarginal portions `of the plastic film S6 are folded back upon themselves, trapping theside edges of the cover between the overlapped portions and form marginal edges'in the attachment tabs consisting of three plies of material, i.e., two layers of plastic film and an intermediate layer of cover material.

' Particular advantages are obtained by the above-described construction. First, less `material is used for the liquid pervious cover of the napkin thereby resulting in considerable economy of manufacture. Second, the slightly compressed bat of cellulosic fibers forming the core of the napkins are completely and firmly encapsulated within the liquid pervious cover and the plastic film, being adhesively stabilized thereto along the bottom and completely around the peripheral side edges, i.e., both longitudinal side edges of the core and at both terminal ends thereof by the cover being adhesively secured to the underlying .plastic film through the area of the attachment tabs. Third, by the plastic film extending to the terminal ends of the attachment tabs, pinning strength is considerably improved. The tensile strength of the plastic material greatly enhances the poor tensile properties of the liquid pervious cover, particularly when the latter consists of paper or nonwoven fabrics. The poor tear resistance of the plastic lm is greatly enhanced by the high tear resistance of the paper -or nonwoven, liquid pervious material. And fourth, the triple-layered adhesively bonded marginal edges of the attachment tabs, when gathered together at the terminal ends, tend to form a hammock-like structure, which resists the normal tendency of sanitary napkins to assume an inverted U shape in transverse cross section when worn. This further aids inform and structural stability of the normally Weak, noncoherent pulp core of the napkin, particularly when being worn.

In some instances, sanitary napkins are made which do not have any attachment tabs, but are maintained in position by separate garments, such as panties, briefs or the like. The -over-all concept of the present invention is equally adaptable to .such type of napkins, `particularly the embodiment shown in FIGS. 9-12. All that is required is Ifor the extending attachment tabs 58 to be cut short, close to the terminal end portions of the core. Thus, encapsulation of the cellulosic pulp core is still maintained, thereby obtaining all the advantages of form and structural -stability obtained in the other embodiments described herein.

As seen `from the foregoing illustrative embodiments of the invention, there is provided a napkin which is economical to make, which effectively prevents strike through of fluid absorbed by the napkin, which prevents side spread failure of the napkin, which has strength, form and structural stability, and which effectively absorbs fluid. It is apparent that variations, modifications and changes in the foregoing examples may be made while still remaining within the spirit and scope of the invention.

What is claimed is:

1. A sanitary napkin comprising a relatively thick, elongated absorbent core, a liquid pervious cover over the top and -sides of said core extending beyond the ends thereof and a thin Flexible film adjacent to said cover and covering the bottom and sides of said core extending beyond the ends thereof coextensive with said cover,

said lm being bonded to said bottom and sides of said core, to the longitudinal side edges of said cover and to said cover in the area extending beyond the ends of said core, said absorbent core consisting essentially of comminuted cellulosic pulp fibers having a uniform density of from about 14 to about 24 grains per cubic inch.

2. A sanitary napkin comprising a relatively thick, elongated absorbent core, a liquid pervious cover over the top and sides of said core extending 4beyond the ends thereof and a thin flexible ,film covering the bottom and sides of said core and extending beyond the ends thereof coextensive with said cover, said cover being positioned intermediate the sides of said core and the portions of said lm covering said sides, said film being bonded to said bottom and sides of said core, to the longitudinal side edges of said cover and to said cover in the area extending beyond the ends of said core, said absorbent core consisting essentially of comminuted cellul'osie pulp bers having a uniform density of from about 14 to about 24 `grains per cubic inch.

References Cited by the Examiner UNITED STATES PATENTS Fourness 128-290 Beery et al. 12S-290 Dube 128--287 Magee 128-296 Hei-manson et al. 12S-287 Morin 12S-284 Makela 128-290 Joa 128-290 Voight'man 12S-290 X Dudley 128-290 Atkinson 128-290 Gobbo et al. 128-287 RICHARD A. GAUDET, Primary Examiner.

20 C. F. ROSENBAUM, Assistant Examiner.

Claims (1)

1. A SANITARY NAPKIN COMPRISING A RELATIVELY THICK, ELONGATED ABSORBENT CORE, A LIQUID PERVIOUS COVER OVER THE TOP AND SIDES OF SAID CORE EXTENDING BEYOND THE ENDS THEREOF AND A THIN FLEXIBLE FILM ADJACENT TO SAID COVER AND COVERING THE BOTTOM AND SIDES OF SAID CORE EXTENDING BEYOND THE ENDS THEREOF COEXTENSIVE WITH SAID COVER, SAID FILM BEING BONDED TO SAID BOTTOM AND SIDES OF SAID CORE, TO THE LONGITUDINAL SIDE EDGES OF SAID COVER AND TO SAID COVER IN THE AREA EXTENDING BEYOND THE ENDS OF SAID CORE, SAID ABSORBENT CORE CONSISTING ESSENTIALLY OF COMMINUTED CELLULOSIC PULP FIBERS HAVING A UNIFORM DENSITY OF FROM ABOUT 14 TO ABOUT 24 GRAINS PER CUBIC INCH.

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