US3375827A - Sanitary napkin with flow control element - Google Patents

Description

April 2, 1968 3,375,827

'1' NAPKIN WITH FLOW COTROL ELEMENT J. c. BLETZINGER ET AL SANITAR Filed March 50, 1965 Irfan:

United States Patent O 3,375,827 SANITARY NAPKIN WITH FLOW CONTROL ELEMENT John C. Bletzinger,` Eugene H. Condon, and Richard C. Simons, Neenah, Wis., assignors to Kimberly-Clark Corporation, Neenah, Wis., a corporation of Delaware Filed Mar. 30, 1965, Ser. No. 443,847 Claims. (Cl. 12S- 290) ABSTRACT OF THE DISCLOSURE This invention relates to sanitary napkins, and more particularly to improvements in sanitary napkin construction which provide more efficient performance, especially with respect to the distribution of absorbent fluids and shape retention during use.

A primary object of the invention is to provide an improved sanitary napkin having incorporated therein a fluid control element and absorbing means which effectively collects body exudates and confines the collected eXudate within a predetermined medial area of the pad.

Another object is to provide a sanitary napkin with a structure which assists in maintaining the shape of the napkin during use.

Still another object is to provide a sanitary napkin of improved performance and comfort.

Other objects and advantages will become apparent to persons skilled in the art upon examination of the description and drawing, without departing from the scope of the invention as defined in the appended claims.

In the drawings, in which like parts are identified by the same reference numeral.

FIG. 1 is a perspective View of an sanitary napkin incorporating one embodiment of the invention, with a top central portion partially cut away to show some details of construction.

FIG. 2 is a section taken alongline 2-2 of FIG. l.

FIG. 3 is similar to FIG. 2 showing an alternate structure.

FIGS. 4 and 5 are similar to FIGS. 2 and 3 but with an additional control element shown along the bottom portion.

FIGS. `6, 7, and 8 are perspective views, partially in section, of various control element structures.

In sanitary napkin construction, it is desirable to have an absorbent structure, which (1) immediately accepts body exudate, (2) rapidly transports the exudate away from the discharge source, and (3) effectively contains the exudate within the confines of the napkin, all while the top surface of the napkin is maintained relatively dry. In addition, the absorbed exudate should not be allowed to spread to the sides of the napkin, run over the top edges of the napkin, or soak through the bottom of the napkin, especially if the absorptive capacity of the napkin has not been reached.

In order to avoid the above problems, and to realize to a greater degree the absorptive and protective potential of sanitary napkins, various means of controlling the spreading of fluid in the pad have been proposed. Among 3,375,827 Patented Apr. 2, 1968 these is the utilization of density or compression differences within, or between, the material used for Various absorptive elements.

This invention defines an improved means for better utilizing the differences in density and pore size of absorptive elements to achieve more effective control of fluid distribution in sanitary pads.

As is well-known in the sanitary napkin art, fluid which is introduced into an absorptive element migrates more rapidly through densiiied areas of such elements than it does through 'areas of less density. That general principle was first taught by Heitmeyer Patent No. 1,863,333, assigned to applicants assignee. Since then many variations of this basic principle have been proposed and patented.

Among the latter is Harwood Patent No. 3,046,986, also assigned to applicants assignee. The Harwood patent employes a fluid control element positioned contiguous to the fluid pervious wrapper. The fluid control element in the patent is provided with a centrally-located embossed portion comprising spaced-apart cup-like depressions whereby the element is substantially densified in the areas marginally of said depressions and throughout the cup-like portions while being of normal uncompressed density in the intervening areas. The described construction is effective in directing recepted fluid in a downward direction to an interiorly placed major absorbent element, and in reducing to some extent transverse flow at the pad surface. However, because the Harwood control element is coextensive with the rest of the pad, transverse and longitudinal migration through the element may occur durin-g heavy flow or when the top element is temporarily saturated causing some side stains and occasional surface overflow.

The present invention largely solves these problems. As shown in the drawings, sanitary napkin 12 comprises a main absorbent core of fluid absorbent material, generally designated 13, a fluid control element 25, and a fluidpervious wrapper 14 `enclosing the absorbent elements and overlapped in a known manner, and providing end ta-bs for fastening purposes. The lluid-pervious wrapper 14 may consist of a woven gauze, a non-woven scrim, a perforated non-woven fibrous web, a light weight web of bonded fibers, or similar materials well-known in the ari.

The main body portion 13 of sanitary napkin 12 may also be of varying construction, including top and bottom layers comprising multiple plies of cellulose wadding 16 and a central pad of wood fluff 18, as shown in FIGS. 2 and 4; or the main lbody portion 13 may be all fluff as shown at 18 in FIGS. 3 and 5. Other known absorbent materials such as batts of cotton and/or various types of synthetic fibers may also be used for the main body portion. The main lbody portion, in itself being of conventional construction, acts only as a cooperating part of the present invention, the important requisite being that the main body portion 13 be lower in density and consequently have larger interstices than the control element 25 hereinafter described.

Other parts of the pad construction are also known, such as fluid-impervious baffles 1'9 of plastic film or the like which are often employed to inhibit strike-through, and side strips 20, such as waxed tissue or water-resistant film may be employed to inhibit inadvertent side-staining caused by migration of exudate to side edges of the pad.

The present invention lies primarily in the construction and location of fluid-control element 25 which cooperates with a main absorbent pad 13 to provide improved performance. The fluid control element may be used smply on the top surface as shown at 25 in FIGS. 1 through 3, or in combination with a similar supplementary element 30 at the bottom of the pad as shown in FIGS. 4 and 5.

In general, elements 25 and 30, comprise a compressed strip of absorbent material of smaller dimension in length and width, than the length and width of main absorbent pad 13. As shown, element 25 is positioned centrally on the top, or body contacting side, of main pad 13, contiguous to the iiuid-pervious wrapper 14. Element 25 is of substantially smaller peripheral dimension than main pad 13, accordingly the end and side edges of element 25 are spaced inwardly a substantial distance from the respective end and side edges of main pad 13. Such spacing of element 25 is extremely important for reasons of both iiuid control and wearing comfort, and is essential to proper functioning of the sanitary napkin of this invention. In the preferred construction, the space from the side edges of the main pad to the side edges of the control element is about Ss. However, this spacing may be varied to be from about 1A to 1" in width. The important considerations in placing the control element 25 with respect to the main pad 13 are: (l) that there be sufficient space from control element edge to main pad edge to prevent transverse migration from the control element to the pad edge, (2) that the control element have sufficient width to be able to transfer iiuid along its length, and (3) that the control element be shorter in length than the main pad.

Element 25 may be compressed overall in a flat nonpatterned configuration as is the element shown at 25e in FIG. 8, or may have an embossed pattern defining various degrees of compression such as in element 25a in FIG. 6, or in element 25b in FIG. 7. In FIG. 6 areas 26a are more highly compressed than areas 27a. In FIG. 7 areas 26b are more highly compressed than areas 27b. It is apparent that many other variations in pattern may be used. The important consideration in constructing the element is that it have a significantly higher average density and smaller pores than the elements 16 and/or 18 which make up main absorbent pad 13.

In sanitary napkins now on the market, cellulose Wadding components such as at 16 and iiuff components such as at 18, have an average apparent density of about 1.9 pounds per cubic foot, or an apparent density range within the component varying from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot.

When material of the above density is used to make up the main pad 13, control element 25 should have an apparent density of over 5 pounds per cubic foot or an apparent density within the element ranging from as low as about 5 pounds per cubic foot at the points of lowest compression to as high as about 100 pounds per cubic foot at the points of highest compression. An average apparent density in the range of about 7.5 pounds per cubic foot to about 50 pounds per cubic foot is preferred. It is understood that when a patterned compression, such as shown in FIGS. 6 and 7, is employed for element 25 that the density and pore size will vary from point to point within the element itself according to the pattern used. However, for the most effective functioning, the lowest density in the major part of element should be substantially higher than the highest density existing in the major part of main absorbent pad 13.

It is believed that during use, the following reaction loccurs in a sanitary napkin of the above construction.

When iiuid strikes compressed element 25, the contacted area immediately expands and the pores in the wetted area become larger. The uid then is drawn to the immediately adjacent smaller pores, which also expand. The absorption and spread of fluid then moves through the element in a continuous liow pattern from the source point of the fluid as long as uid is being supplied. Very little iiuid appears to transfer to the main absorbent pad 13 in the early stages of use because of the strong capillary action of the small pores which exist within denser element 25 as compared with the larger pores which exist within the main absorbent pad 13 construction. However, depending upon the length of time the pad is worn, more and more of the iinid in element 25 is transferred by gravity or free flow to main absorbent pad 13, and rate of transfer between element 25 and main absorbent pad 13 increases as local areas in element 25 are temporarily saturated. Thus, as iiuid is introduced to element 25, it tends to spread rapidly in both the lengthwise and transverse directions even if the iiuid is introduced at a remote end thereof, -before any substantial amount reaches, or is transferred to the main absorbent pad 13. The transfer of fluid to the main absorbent pad which starts at a slow rate and gradually increases is largely confined to an area in the main absorbent pad defined by the marginal edges of element 25. This is believed to be true because the forces which govern the transverse and lengthwise migration of liuid are stronger, due to higher capillarity within the smaller pores of the compressed element, than such forces are in the main absorbent pad, and the transfer to the main absorbent pad is largely the result of gravity 0r free iow. As a result, the iiuid which first srtikes the surface of the napkin is effectively confined within the dimensions of the compressed element and fluid will not overow the sides or edges of the main absorbent pad unless all of its central absorbent capacity is utilized.

The higher density of the control element 25 also aids in maintaining the dimensioned stability of the pad whereby the pad has increased ability to hold its shape during use. In locating the element centrally of the top surface of the main absorbent pad, it is possible to provide a relatively planar surface in the principal area of Contact between the pad and the perineal area of the wearer. The relatively less dense main body portion of the pad extending beyond the edges of the compressed element is soft and uify and conforms readily to the thighs and body movement to insure against chang and avoid discomfort.

The dimensional stability is further improved when a second control element 30 is located at the bottom of the main absorbent pad. The second or bottom control element 30 is preferably of the same dimensions and density as the first, or top, control element 25 and is positioned centrally of the main absorbent pads bottom surface similarly to, and congruent with, the position of top element 25 with respect to the top pad surface.

Structure of this latter type is exemplified in FIGS. 4 and 5. In FIG. 4 the main absorbent pad comprises multiple layers of absorbent cellulose wadding 16 on each side of a central liuii section 18. In FIG. 5, the main absorbent pad is comprised only of a iiuif section 18.

As shown in the drawings, the compressed elements, top 25 and bottom 30, provide dimension stabilizing components and are made relatively narrow to more readily accommodate the narrow dimension of the perineal crotch without undue side compression. The soft central element, or main absorbent pad, is wider than the compressed element permitting it to contract and expand as required by body movements and pressures while the top and bottom compressed elements remain essentially planar.

The structure shown in FIGS. 4 and 5 is also suitable for two-sided or reversible sanitary napkins, i.e., napkins which may be worn with either side facing upwardly. When a reversible napkin in desired, the conventional polyethylene bafiie, shown lat 19 in FIGS. 2 and 3 is either eliminated entirely, or is located within the main absorbent pad intermediate the top and bottom surfaces of the napkin. In Ithe event a napkin of such construction is worn upside down, element 30 acts to control spread of the exudate in the same manner as described previously for element 25.

In producing the compressed elements 25 and 30, a -large variety of embossing patterns may be used. The elements may be totally compresed without a pattern (FIG. 8), or they may be compressed in a range of patterns to provide gradient densities which result in varying degrees of resilience and softness to the touch (FIGS.

6 and 7). Dimensions of the compressed element and main pad may also be varied to provide a range of sizes to accommodate the normal range of perineal dimensions.

In one specic example, the compressed elements were 5" long and 11A" wide and the soft middle section comprising the main absorbent pad were 8% "long and 2li/16 wide. The middle section had an average apparent density of about 1.9 pounds per cubic foot and the compressed elements had an average apparent-density of about 24 pounds per cubic foot. While the drawing shows the control e-lements as being redtangular, the ends may be Irounded or the element may have an oval configuration. In each of these alternate forms, however, the peripheral edges of the control element must stil-l be spaced from the respective peripheral edges of the main absorbent pad.

Also in constructing the control elements a variety 0f absorbent materials may be employed. Materials which have proved satisfactory include wood uif, a combina- Ition of wood fluff and uniformly interspersed pieces of shredded sponge such as polyurethane and cellulose sponge, multilayers of cellulose wadding, absorbent cotton, and various combination of such materials.

In connection with the control element 25a, illustrated in FIG. 6, it will be observed that the more highly compressed areas 26a in adjacent rows are staggered with respect to each other. We have found, with this staggered relationship, that fluid migrates easily from one compressed area 26a to adjacent compressed areas 26a in adjacent rows, diagonally across the control element. This migration occurs particularly within the lower surfaces of the control element, leaving the relatively uncompressed areas on the top surface of the element, as appearing in FIG. 6, dry for a time While the fluid continues to migralte and flow within the element 25a. In case the fluid ow to the control element 25a is quite limited, the uid flow remains on the lower surface of the control element and penetrates from there onto the main body of the pad while leaving the top surface of the corrtrol element 25a in contact with the human body in dry condition. The compression of the areas 26a apparently reduces the capillary voids in cross section within the control element 25a causing migration of fluid to occur particularly internally of and on the underside of the control element 25a, between the compressed areas 26a, leaving the outer, less compressed, surfaces drier.

It is apparent that various changes in the described structure may be made without departing from the principles of the invention.

What is claimed is:

1. A sanitary napkin comprising a main uid absorbent pad, a separate fluid control element, and a fluid previous wrapper enclosing said pad and said element, said control element comprising absorbent material of substantially higher average apparent density than the average apparent density of the absorbent material in said pad, the length and width dimensions of said element being smaller than the length and width dimensions of Said pad, said element being centrally positioned on said pad.

2. A sanitary napkin comprising a main fluid absorbent pad, a pair of separate fluid control elements, and a fluid pervious wrapper enclosing said pad and said elements, said elements comprising absorbent material of substantially higher average apparent density than fthe average apparent density of the absorbent material in said pad, the length and width dimensions of said elements being smaller than the length and width dimensions of said pad, one of said elements being centrally positioned on the 'top of said pad, and the second of said elements being centrally positioned on the bottom of said pad.

3. A sanitary napkin comprising an assembly of elongate fluid absorbent components enclosed in a fluid pervious wrapper, said assembly comprising a main absorbent pad having an average apparent density in the range of from about 1.5 pounds per cubic foot lto about 2.5 pounds per cubic foot and a separate fluid control element having an average apparent density in the range of about 5 pounds per cubic foot to about pounds per cubic foot, the peripheral dimension of said element being substantially less than the peripheral dimension of said pad, said element being positioned on top of said pad and inwardly spaced from the periphery thereof.

4. The napkin of claim 3 in which the space between the side edges along the periphery of said element and the side edges along fthe periphery of said pad is from M1" to about l". p

5. A sanitary napkin comprising an assembly of elongate fluid absorbent components enclosed in a fluid pervious wrapper, said assembly comprising a main absorbent pad having an average apparent density in the range of from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot and a pair of separate uid control elements having an average apparent density in lthe range of about 5 pounds per cubic foot to about 100 pounds per cubic foot, the peripheral dimension of said elements being substantially less than the peripheral dimension of said pad, one of said elements being positioned on .top of said pad and inwardly spaced from the periphery thereof, the other of said elements being positioned on the bottom of said pad and inwardly spaced from the periphery thereof.

6. A sanitary napkin comprising an assembly of elongate uid absorbent components enclosed in a fluid pervious wrapper, said assembly comprising a. main absorbent pad having an average apparent density in the range of from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot and a separate fluid control elemenlt having an average apparent density in the range of about 7.5 pounds per cubic foot to yabout 50 pounds per cubic foot, the peripheral dimension of said element being substantially less than the peripheral dimension of said pad, said element being positioned on top of said pad and inwardly spaced from the periphery thereof.

7. A sanitary napkin comprising an assembly of elongate fluid absorbent components enclosed in a iiuid pervious wrapper, said assembly comprising a main absorbent pad having an average apparent density in the range of from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot and a pair of separate fluid control elements having an average apparent density in the range of about 7.5 pounds per cublic foot to about 50 pounds per cubic foot, the peripheral dimension of said elements being substantially less than the peripheral dimension of said pad, one of said elements being positioned on top of said pad and inwardly spaced from the periphery thereof, the other of said elements being positioned on the bottom of said pad and inwardly spaced from the periphery thereof.

8. A sanitary napkin comprising a main luid absorbent pad, a separate uid control element in association therewith, and a uid pervious wrapper enclosing said pad and said element, said element having a pattern impressed therein comprising areas of high density and areas of low density, the apparent density of said low density areas being substantially higher than the highest apparent density of said pad, said element being non-coextensive with said pad and being positioned on top of said pad with the edges of said element spaced inwardly from the outside edges of said pad.

9. A sanitary napkin comprising a main liuid absorbent pad, a separate fluid control element in association therewith, and a fluid pervious wrapper enclosing said pad and said element, said element having a pattern impressed therein comprising areas of high densilty and areas of low density, the apparent density of said low density areas being substantially higher lthan the highest apparent density of said pad, the average apparent density of said pad being in the range of from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot, the apparent density of said element ranging from as low as about 5 pounds per cubic foot in the low density areas to as high as about 100 pounds per cubic foot in the high density areas, the peripheral dimension of said element being substantially less than the peripheral dimension of said pad, said element being positioned on top of said pad and inwardly spaced from the periphery thereof.

10. A sanitary napkin comprising a main fluid absorbent pad, a pair of separate uid control elements in association therewith, and a uid pervious wrapper enclosing said pad and said element, said element having a pattern impressed thereon comprising areas of high density and areas of low density, the apparent density of said low density areas being substantially higher than the highest apparent density of said pad, the average apparent density of said pad being in the range of from about 1.5 pounds per cubic foot to about 2.5 pounds per cubic foot, the apparent density of said element ranging from as low as aboult 5 pounds per cubic foot in the low density areas to as high as about 100 pounds per cubic foot `in the high density areas, the peripheral dimension of said element being substantially less than the peripheral dimension of said pad, one of said elements being positioned on top of said pad and inwardly spaced from the periphery thereof, and the other of said elements being positioned at the bottom of said pad and inwardly spaced from .the periphery thereof in congruency with said top element.

References Cited UNITED STATES PATENTS 2,952,260 9/1960 Burgeni 12S-290 3,017,304 l/1962 Burgeni 12S-290 3,046,986 7/1962 Harwood 128-290 3,029,817 4/1962 Harwood et al. 128--290 RICHARD A. GAUDET, Primary Examiner.

CHARLES F. ROSENBAUM, Examiner.

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