IE41811B1

IE41811B1 - Adhesively attached absorbent product

Info

Publication number: IE41811B1
Application number: IE2243/75A
Authority: IE
Original assignee: Personal Products Co
Priority date: 1974-10-16
Filing date: 1975-10-15
Publication date: 1980-03-26
Also published as: US3913580A; JPS5913212B2; CA1056103A; ZA756523B; JPS5185297A; DE2546208A1; IE41811L; AU8508475A

Abstract

An absorbent product is disclosed which includes a fluid impervious barrier sheet at one side thereof adhered to an absorbent pad that is surrounded, at least in part, by a fluid pervious cover to be positioned against the body of the wearer. The barrier sheet includes a central strip of pressure sensitive adhesive for adhering the absorbent product to a garment, and a protective cover strip is releasably adhered to the pressure sensitive adhesive. The barrier sheet is secured in place by a plurality of spaced parallel lines of adhesive on the surface thereof opposite to the strip of pressure sensitive adhesive. This surface also includes a band of adhesive in alignment with the strip of pressure sensitive adhesive to reinforce the mid-portion of the product and prevent different sections of the strip of pressure sensitive adhesive from inadvertently adhering to one another once the protective cover strip has been removed. The band of adhesive includes a rectangular area generally coextensive with the length of the absorbent pad, and a plurality of lines of adhesive extend outwardly from opposite ends of the generally rectangular area into the tab portions of the product. Such lines of adhesive are spaced from one another by a distance generally the same as the distance between the lines of adhesive outwardly of the adhesive band.

Description

This invention relates in general to absorbent products of the sanitary napkin type, and particularly to such products which are retained in place by adhesive adherement to a garment of the wearer to provide protection for such garment.

Such adhesively attached absorbent products have met with significant commercial success in the recent past, and have been particularly convenient to use In the days preceding a woman’s menstrual cycle and at the end of the menstrual cycle Such products have also had widespread use during periods of heavy discharge as added protection for a woman using a tampon. Women have also found it convenient to use such products in between menstrual cycles to protect undergarments against body discharges and when using various medicaments.. These products are particularly convenient to use, since they do not require any pins, belts or special undergarments, and can be readily retained in place by merely pressing the adhesive into engagement with an under garment. -241811 Absorbent products of the above type conventionally have included an absorbent core or pad formed entirely of short cellulose fibers, such as cotton linters or wood pulp fibers, or mixtures thereof, held together primarily by interfiber bonds, and which are commonly referred to as fluff. Such pads are generally rectangular both in plan view and in cross section, and are surrounded by a soft fluid pervious body engaging cover, such as an apertured nonwoven fabric as disclosed, for example, in · U.S. Patent numbers 2,862,251; 3,081,514 and 3,081,515. The side of the product opposite from the side to be positioned against the body of the wearer has conventionally included a thin fluid impervious barrier sheet formed of a material such as polyethylene. Such a sheet Is normally adhesively adhered to the remainder of the absorbent product, and the exposed outer face of the barrier sheet Is provided with a strip of pressure sensitive adhesive for securing the product to a garment such as underpants. A protective cover strip is releasably adhered to the strip of adhesive, and is removed just prior to use of the product. The covers and barrier sheets that are used in absorbent products of the type described above are usually longer than the absorbent pads to confine the pad to the interior of the product, and to provide tabs at opposite ends of the product.

One of the problems that has been encountered in the past is to adequately control the amount of adhesive substance that is utilized to secure the barrier sheet in place on the product, since if too much adhesive is used, undesirable stiffening occurs, particularly in the tab area, and if too little adhesive is used, the absorbent product can come apart when subjected to stress. -341811 Another vexatious problem that arises in the use of products as described above results from the fact that the barrier sheet that is utilized to retain body fluids within the product is extremely thin and flexible. As a result, when the protective cover strip is removed from the pressure sensitive adhesive, unless the user of the product is extremely careful, it is possible that different sections of the pressure sensitive adhesive will adhere to otte another, oftentimes causing permanent creasing or wrinkling of the barrier sheet and sometimes making the product unusable. The problem is complicated by the fact that the exposed pressure sensitive adhesive must be readily adhereable to the garment of the wearer, so that of necessity, the pressure sensitive adhesive must be extremely tacky. As a result, when different sections of the pressure sensitive adhesive stick to one another, they are extremely difficult to pull apart. Should this occur in use, as a result for example of the constant stresses to which the product is subjected to when worn, these selfadhered portions will no longer be available to maintain the product in its proper position and, as a result, the product may shift out of position.

Summary of the Invention tf The present invention provides a solution to the problems set forth above by virtue of a unique adhesive pattern 2r> for joining the barrier sheet to the remainder of the absorbent product. The adhesive pattern includes a continuous band of adhesive which extends from end to end of the barrier sheet on the side thereof opposite from the pressure sensitive adhesive -441811 and in alignment therewith, which band adds significant strength to the barrier sheet in the cross direction. The band of adhesive includes a generally rectangularly shaped midportion which extends a major portion of the length of the barrier sheet and which is preferably slightly wider than the strip of pressure sensitive adhesive, although this is not critical to the present invention.

The adhesive pattern further includes a plurality of spaced continuous and parallel lines of adhesive on opposite sides of the band of adhesive, which lines extend from end to end of the barrier sheet, and which cooperate with the band of adhesive to bond the barrier sheet to the underlying portion of the absorbent product. The band of adhesive also includes a plurality of spaced lines which extend outwardly from the rectangular area at opposite ends thereof, with the lines of the band being spaced from one another by about the same distance as the lines outwardly of the band.

The generally rectangular area of the band of adhesive corresponds in length to the pad of the absorbent product, with the lines at the opposite ends of the band being present in the tabs of the product. With the above described adhesive pattern, a continuous band of adhesive is provided from end to end of the barrier sheet, with lesser amount of adhesive being present in the tab area than in the remainder of the product, During manufacture of the absorbent product, the sub-assembly consisting of the pad and fluid pervious cover is brought into registry with the barrier sheet having the above described adhesive pattern thereon, and the resulting structure is subjected to compression in the areas outwardly of the 541811 absorbent pad to cause the adhesive on the barrier sheet to spread slightly in the tab area and to bond positively with the cover of the product. By virtue of providing spaced lines of adhesive outwardly of the rigidifying rectangular area of the continuous band of adhesive, not only is the amount of adhesive necessary to complete the product minimized, but also an effective tab seal is created without stiffening of the tabs. The lesser quantity of adhesive in the tab areas (as compared to the generally rectangular area of the band), also prevents bleed-through of the adhesive substance during the compression step, which otherwise could foul the processing equipment and prevent an effective high-speed production i operation.

The continuous central hand of the adhesive pattern can be applied simultaneously with the application of the adhesive lines outwardly thereof, or in a separate processing step.

In either event, the band is preferably formed by discharging an appropriate adhesive substance onto the barrier sheet through openings in the metering valve, and controlling the valve such that the adhesive substance pools or floods the area of the barrier sheet immediately adjacent to the metering valve during formation of the generally rectangular area of the band and forms discreet lines of adhesive outwardly of the ends of the generally rectangular area in those sections of the hand corresponding to the tab areas of the product. The basic weight of the lines outwardly of the ends of the generally rectangular area is substantially the same as the lines at opposite sides of the rectangular area, so that the strength of the tab seal is generally uniform throughout the width of the product. -641811 Brief Description of the Drawings Fig. 1 is a perspective view of an absorbent product formed in accordance with the teachings of the present invention, with certain portions of the product being folded back or torn away to expose underlying portions; Fig. 2 is a plan view of the undersurface of the barrier sheet of the absorbent product of the present Invention; Fig. 3 is a cross-sectional view taken generally along line 3-3 of Fig. 1; io Fig. 4 is a cross-sectional view taken generally along line 4-4 of Fig. 1; Fig. 5 is a bottom plan view of a metering valve which may be used to form the central band of adhesive on the undersurface of the barrier sheet; and Fig. 6 Is a cross-sectional view taken generally along line 6-6 of Fig. 5.

Detailed Description of the Preferred Embodiment While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of * the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. -741811 The absorbent product of the present invention is illustrated in its entirety at 10 in Fig. 1, and includes an absorbent core or pad 12, a fluid pervious cover 14, and a fluid impervious barrier sheet 16. Absorbent pad 12 is .formed entirely of loosely compacted short cellulosic fibers, i.e., fibers having a length less than about At, and preferably is in the form of a low-bulk density batt referred to conventionally as fluff, wherein the fibers are retained together by interfiber bonds without the use of added adhesive. Pad 12 may be formed of wood pulp fibers or cotton linters or mixtures thereof. Pad 12 is generally in the shape of a rectangular parallelpiped as is evident by comparing Pigs. 1 and 3.

A wide variety of fabrics may be utilized as cover 14, so long as the fabrics are soft, dimensionally stable, and pervious to body fluids. Apertured nonwoven fabrics of the type described in the previously mentioned patents have been found to be particularly well-suited for the present invention. Cover 14 is rectangular in shape and wider and longer than pad 12. The side marginal edges 14a and 14b (Figs. 3 and 4) of the cover are folded around the opposite side edges of the pad, so as to he present at the outer side of the product, i.e., that side which faces away from the body of the wearer and which is to be adhered to an undergarment, as will hereinafter appear. While cover portions 14a and 14b have been illustrated as being spaced from one another, the present invention contemplates that a wider cover may be utilized, with the opposite edges being folded into close proximity or even into overlapping relationship with one another. -841811 Barrier sheet 16 is formed of a thin fluid impervious film material, such as polyethylene, and barrier sheet 16 is also rectangular, corresponding in length to cover 14 and approximately in width to pad 12. A polyethylene sheet 2 mils thick has functioned very satisfactorily as a barrier sheet in the present Invention. A strip 18 of tacky pressure sensitive adhesive is provided on the outer face of barrier sheet 16, and extends continuously from end to end thereof. Pressure sensitive adhesive strip 18 covers a rectangular area which is centrally located on the exposed side of barrier sheet 16, and a protective cover strip 20 is releasably adhered to adhesive 18 to protect the same prior to use of the product. Protective strip 20 may be slightly wider than adhesive strip 18. The pressure sensitive strip 18 may be coated directly onto the barrier sheet, applied to protective cover strip 20 and transferred to the barrier sheet (as is described in -- ’ U.S. Patent number 3,595,237), or may be provided by a double faced adhesive tape, as will be well understood by those skilled in the art. In any event, once protective strip 20 Is removed, adhesive strip 18 provides an exposed tacky mass which is utilized to retain the product in place on the garment of the wearer but which would, prior to the Incorporation of the barrier sheet adhesion system of this Invention, require great care on the part of the user to avoid the problems of self adhesion herein referred to.

In accordance with this invention, there is provided, on the undersurface or inner surface 22 of barrier sheet 16, a continuous central adhesive band 24 in alignment with adhesive, strip 18 and a plurality of spaced parallel adhesive lines 26 arranged outwardly and on opposite sides of band 24.

As is evident from Fig. 2, lines 26 extend continuously -941811 from end to end of the barrier sheet (the length of the barrier sheet being denoted by the broken lines in Fig. 2), and are disposed in parallelism with the sides of the sheet and with band 24. Band 24 includes a generally rectangularly shaped midportion 28 which extends a major portion of the length of the barrier sheet, and a plurality of equally laterally spaced parallel lines 28a extending outwardly from each end of rectangular area 28. Rectangular area 28 corresponds in length generally with pad 12 and lines 28a extend outwardly from pad 12 so as to be present in tabs 30 at opposite ends of the product. The distance between lines 28a is generally the same as the distance between lines 26, and the quantity of adhesive per unit length for all of the lines is essentially the same so that the strength of the tab seals will be uniform across the width thereof.

Band 24 can be formed simultaneously with the formation of lines 26 or in a separate processing step. The same or different adhesives can be used. A metering valve 32, which may be utilized to form band 24 is shown in Figs. 5 and 6, and valve 32 forms the desired adhesive pattern on a continuous web of barrier sheet film stock by a wiping action as the filmmoves beneath the valve in engagement with the lower surface thereof.

Valve 32 includes a body 34 having a chamber 36 therein, which converges downwardly, as can be seen in Fig. 6. An appropriate adhesive substance under pressure is admitted into chamber 36 through inlet 38, and is forced from chamber 36 through downwardly extending discharge ports 40, there being one such discharge port for each line 28a.

The lower end of valve body 34 is undercut at 42 to define a recess in which adhesive from ports 40 is collected.

A control spool 44 Is mounted for vertical movement within ' valve body 34 for controlling the quantity of adhesive flowing through ports 40. The lower end 46 of the control spool Is tapered corresponding to the taper at the lower end of chamber -1041811 36. and when lines 28a are formed on the film of barrier sheet material passing directly below valve 32, spool 44 is moved downwardly to locate lower end 46 in flow-restricting relationship with respect to ports 40 so that adhesive flows directly onto the barrier film from ports 40. When rectangular areas 28 are to be formed on the barrier film, the spool 44 is moved upwardly out of flow-restricting relationship with respect to ports 40, and adhesive under pressure is forced outwardly to fill the recess formed by undercut 42, so that the area 28 ie continuous both lengthwise and transversely.

The exact position of the valve spool relative to the valve chaaber during formation of band 24 will depend on many factors, such as whether a cold or a hot melt adhesive is used, i the viscosity of the particular adhesive, the rate of movement of' the barrier film, etc. Also, the structure of the metering valve itself is not critical to the present invention, and configurations other than that illustrated in Figs. 5 and 6 will suggest themselves to those skilled in the art.

During manufacture of the absorbent product, subassemblies consisting of spaced pads 12 partially wrapped with cover 14 are fed into juxtaposition with the sheet of adhesively coated barrier film material in timed relationship with respect to the reciprocation of spool 44 so that the lines 28a are in registry with the portions of the cover between the pads. · The resulting sandwich structure is then subjected to light compaction between compression rolls, to cause the adhesive lines 26 and the adhesive band 24 to penetrate into and bond with the adjacent underlying fibrous portion of the product. -11418 11 As is clear from Figs. 3 and 4 in the illustrated embodiment of the invention, two sets of two adhesive lines 26 bond barrier sheet 16 to each of the inwardly folded edges 14a and 14b of the cover 14, while two sets of four adhesive lines 26 bond the barrier sheet 16 to pad 12 at each side of band 24 and four adhesive lines 28a are present at the ends of band 24 in the tabs 30. In one preferred form of the invention, wherein the barrier sheet was 1-3/4 inches wide, adhesive lines 26 and 28a were about 3/64 inch in width, with rectangular area 28 being about 3/8 inch in width. The entire adhesive pattern on the barrier sheet was about .004 inch thick, and was found to provide a secure bond between the barrier sheet and the remainder of the absorbent product. By having spaced adhesive lines 28a in the tab portions of the product, as compared to a transversely continuous area of adhesive like area 24, undue stiffening of the tabs is prevented. Furthermore, the controlled lesser amount of adhesive in the tab portions prevents bleed-through of the adhesive during the product compressing step and consequent fouling of the processing equipment.

The rectangular area 28 of band 24 is preferably at least as wide as the pressure sensitive adhesive strip 18, and in the embodiment described in the preceeding paragraph, the pressure sensitive adhesive strip was 1/4 inch in width and the rectangular area was 3/8 inch in width. Such an area was found to reinforce the mid-portion of the barrier sheet and provided increased resistance to wrinkling of the barrier sheet, thereby minimizing the likelihood of one portion of the pressure sensitive adhesive being inadvertently adhered to another once the protective covering strip has been removed therefrom.

Claims

WHAT IS CLAIMED IS:

1. An absorbent product for adhesive attachment to a wearer's garment comprising: an absorbent pad having longitudinal sides, transverse 5 ends, a first generally rectangular face to be disposed toward the body of the wearer and a second generally rectangular face to he disposed toward the garment of the wearer, a fluid pervious cover positioned adjacent said first face, said cover being generally rectangular and larger and wider ι ίθ than said pad; the opposite longitudinal marginal portions of said cover being folded over adjacent and longitudinal sides of said pad and extending inwardly over the second face of said pad; a fluid impervious barrier sheet overlying said inwardly 15 extending portion of eaid cover, said barrier sheet being generally coextensive in length with said cover; pressure sensitive adhesive means extending longitudinally on the outer face of said barrier sheet; a protective strip covering said pressure sensitive ad20 heeive means and releasably adhered thereto; and ./ 418 11 adhesive means on tho inner face of said barrier sheet for attaching said barrier sheet to said product, said adhesive means comprising a plurality of lines extending longitudinally of said barrier sheet and parallel with the side edges of said 5 pad and a band of adhesive coaligned with and beneath said pressure sensitive adhesive means, said band of adhesive being at least as wide as said pressure sensitive adhesive means.

2. A product as set forth in Claim 1 wherein said pressure sensitive adhesive means and the band of adhesive are located 10 in the center of said barrier sheet.

3. A product as set forth in Claim 1 wherein said band of adhesive covers a continuous generally rectangularly shaped area of said barrier sheet, said area being generally coextensive in length with said pad. '5.

4. A product as set forth in Claim 3 wherein spaced lines of adhesive extend outwardly from each end of said band of * adhesive.

5. An absorbent product having an inner face adapted to be disposed toward the body of the wearer and an outer oppositely 20 directed face, said product comprising: an absorbent pad; a fluid pervious cover adjacent said pad at the inner face of the product, opposite side marginal portions of said cover being -1441811 folded over adjacent side edges of said pad and extending inwardly over the outer face of the product; a fluid impervious barrier sheet outwardly of the inwardly extending portions of said cover, said barrier sheet being generally coextensive in length with said cover; pressure sensitive adhesive means on the outer face of said barrier sheet for attaching said product to an undergarment or the like; and adhesive means on the inner face of said barrier sheet for attaching said barrier sheet at the outer face of the product, said latter adhesive means including a plurality of transversely spaced lines of adhesive extending longitudinally of said barrier sheet and parallel with the side edges of said pad and a band of adhesive in alignment with said first mentioned pressure sensitive adhesive means, said band of adhesive being at least twice as wide as any of said lines of adhesive,

6. A product as set forth in Claim 5 wherein said band of adhesive covers a continuous generally rectangularly shaped area of said barrier sheet, said area being generally coextensive in length with said pad. -1541811

7. A product as set forth in Claim 6 wherein spaced lines of adhesive extend outwardly from each end of said continuous generally rectangularly shaped area.

8. The method of forming an absorbent product comprising 5 the steps of: providing a fluid impervious barrier sheet having a pressure sensitive adhesive means on one side thereof;. applying an adhesive substance to the side of said barrier sheet opposite said pressure sensitive adhesive means by depositing (a) a band of adhesive in alignment with said pressure sensitive adhesive 1.0 means and (b) a plurality of spaced lines of adhesive outwardly of opposite sides of said band; and attaching an absorbent member to said adhesive substance.

9. The method of Claim 8 in which said adhesive band depositing step is further characterized by depositing adhesive 15 substance over a continuous generally rectangularly shaped area * having spaced lines of adhesive substance extending outwardly from opposite ends thereof, and wherein said attaching step is performed by adhering said absorbent member to said continuous generally rectangularly shaped adhesive area and to the lines of 20 adhesive outwardly thereof. -1641811

10. The method of forming an absorbent product comprising the steps of: providing a fluid impervious harrier sheet; applying an adhesive substance to one side of said barrier sheet by depositing a band of adhesive and a plurality of spaced 5 lines of adhesive outwardly of opposite sides of said band; and attaching an absorbent member to said adhesive substance.

11. The method of forming an absorbent product from first and second components comprising the steps of: applying an adhesive substance to one side of said first component by de10 positing a band of adhesive and a plurality of spaced lines of adhesive outwardly of opposite sides of said band; and attaching said second component to said adhesive substance.

12. The method of Claim 11 wherein said first component is a fluid impervious barrier sheet. '15

13. An absorbent product for adhesive attachment to a wearer’s garment substantially as hereinbefore described with reference to or as illustrated in the accompanying drawings.