GB1597799A - Reusable adhesive tape tab for disposable diapers - Google Patents

Description

(54) RE-USABLE ADHESIVE TAPE TAB FOR DISPOSABLE DIAPERS (71) We, JOHNSON & JOHNSON, a Corporation organised under the laws of the State of New Jersey, United States of America, of 501 George Street, New Brunswick, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an improved adhesive tape tab for use on disposable diapers. More particularly, this invention relates to an improved adhesive tape tab which permits a disposable diaper to be reopened after a closure has been made without tearing the plastics film outer surface of the diaper or the tape tab itself, and which tape tab can be reused for subsequent fastenings of the diaper.

It has become very common and practical to use adhesive tape tabs on disposable diapers. The practical advantage of tape tabs over pins for use with disposable diapers is self-evident; however, there are shortcomings involved in the use of adhesive tape tabs. For instance, when a child reaches the toilet training stage its diaper must be opened and could thereafter be used again provided another diaper closure could be made. The major shortcoming in the known adhesive tape tabs is that an additional closure cannot be made, and the diaper once opened, must be discarded. In most instances, while attempting to separate the adhesive tape tab from the outer surface of the diaper, usually a thin plastics film, the film is torn or the tape tab itself is torn. The torn tape tab or diaper outer surface makes refastening very cumbersome, if not practically impossible.

In some instances, pieces of the torn outer surface may remain attached to the adhesive tab, rendering it unusable. In addition, the tearing of the outer surface may expose the absorbent material inside the diaper, pieces of which may drop out of the diaper. Usually, the consumer has to discard unsoiled diapers because the attempt to open the diaper has torn the diaper outer surface. The same problem is confronted when one attempts to open a disposable diaper to check for soiling.

The inability to refasten the diaper due to the tearing of the outer surface arises from use of very thin plastics film as the fluid impermeable outer surface in nearly all disposable diapers. This thin plastics film is economical, flexible and supple, and acts as a barrier for retaining fluids within the diaper. While the known adhesive tape tabs make a reliable first fastening on the film, the peel strength of the tab is greater than the tear strength of the film, causing the film to tear when attempts are made to peel the tape from the film. Using a thicker plastics film would increase the cost of the disposable diaper and reduce the flexibility and suppleness of the outside surface with no assurance that tearing will not occur under variable tape fastening conditions.

Reducing the peel strength of the tape tab to less than the tearing strength of the film runs the risk that the holding strength of the adhesive tab will be reduced to the point of ineffectiveness in maintaining a diaper closure.

Recently there have been attempts to provide the disposable diapers with adhesive tape tabs which can be used more than once. In USP 3,848,596 the tape tab fastening means provides an arrangement which is essentially useful for only two fastenings, the original and one more. Use of multiple release sheets on the tape tab provides refastening ability. The multiple release sheets are, however, limiting elements in the refastening or repositioning ability of the tapes and add cost in the manufacture of the diapers. In a possible arrangement which we have recently had under consideration, a conventional tape tab is made repositionable by applying a non-adhesive open mesh sheet material to the adhesive fastening surface. The adhesive material is thereby interrupted and divided into segments each of which has an area such that the peel strength over each segmented area, between the tape and the film, is less than the tearing strength of the film over the same segmented area. While such a tape tab is repositionable, it requires the use and expense of the non-adhesive open mesh sheet material.

The prior art also reveals the use of a plastics film as the support for the adhesive tape tape. The adhesive, when applied to a tape having a plastics surface, rather than a paper tape, lies in a thin, smooth layer, giving a uniform, continuous adhesive surface. The conformability of the thin, flexible plastics film tape tab and the smooth adhesive layer thereon to the thin plastics film outer surface of the diaper gives excellent holding power to the tape tab. In addition, the plastics film tape tab requires considerably less adhesive than the conventional paper tape tabs, thereby yielding a cost saving.

The prior art also discloses tape tabs with a non-adhesive portion, or hinge, between the adhesive coated closure segment and the segment by which the tape tab is first affixed to the diaper. The hinge allows limited movement between these two segments of the tape tab in a diaper closure, providing comfort for the wearer. Additional movement causes lifting, peeling forces to be applied to the adhesive closure segment, by the hinge. When the adhesive closure segment of the tape tab can be separated from the diaper outer surface, as in the present invention, the wearer may cause sufficient movement to peel away enough of the segment to undo the closure. Use of the plastics film in forming the repositionable tape tab of the present invention yields a "limp" hinge which does not communicate lifting, peeling forces to the adhesive closure segment. In a preferred embodiment of the present invention, the plastics film of the tape tab is elastic, providing even greater movement between the two tape closure segments, and yielding greater comfort to the wearer.

An improved economical adhesive tape tab which may be fastened, opened and refastened a number of times to the plastics film outer surface on a conventional disposable diaper has now been discovered.

The adhesive tape tab requires only one adhesively coated tape for utility, uses considerably less adhesive than a conventional diaper tape tab, may be fastened to the presently used thin plastics film diaper outer surfaces, and most importantly can be separated therefrom without tearing the diaper outer surface or the tab itself.

The primary advantage of this new adhesive tape tab is the cost saving gained from using disposable diapers many times, until soiled. When children are in the toilet training stage, the reusability feature is a significant advantage. Besides the cost savings, the reuse of the same diaper is a convenience measure since an additional diaper does not have to be available every time the child makes an attempt to learn the significance of the toilet.

Another advantage of this new adhesive tape tab is the flexibility of the plastics film tape material and its conformability to the plastics film outer surface of the diaper providing a tape tab that is aesthetically pleasing to the touch and highly tear resistant, as well as requiring less adhesive than the conventional paperbacked diaper tape tab. The plastics film tape material is strong and moisture repellent as well as being flexible, giving improved strength at the junction of the tape and the outer edge of the diaper.

In accordance with the principles of this invention, an improved adhesive tape tab is provided for repositionable and reapplicable use on any of the well known disposable diapers having a thin plastics film outer surface. The tape tab of the present invention is made of a strip of thin plastics film and has a first segment attached to the diaper, and a second segment, a portion of which is coated with a repositionable adhesive coating for fastening on the outer surface of the diaper; the distal portion of the second segment, being non-adhesive, serves as a pull tab. In a preferred embodiment, the portion of the second segment which lies adjacent the first segment is non-adhesive and flexible, and acts as a hinge between the two diaper fastening ends of the tape. Any flexible plastics film material such as polyester or polypropylene may be used to form the tape tab, which should preferably has a thickness of 4 mils or less. The tape tab may, if desired, utilize a coated release sheet or be attached to release coated material on the diaper facing before use. The adhesive disposes itself on the plastics film in a smooth, uniform layer. It is believed that the smooth adhesive layer and the flexibility of the plastics tape backing contribute to the superiority of the fastening strength of the plastics backed tape tab over a similarly constructed paperbacked tape tab.

These and other advantages, features and aspects of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings, wherein: Figure 1 is a plan view of a tape tab according to the present invention affixed to the outer surface of a disposable diaper and ready for fastening.

Figure 2 is a plan view of a portion of the preferred embodiment of the tape tab of the present invention extended beyond the diaper ready for fastening, as viewed toward the inside surface of a disposable diaper.

Figure 3 is a perspective view of a disposable diaper fastening made with the preferred embodiment of the tape tab of the present invention.

In Figure 1, a tape tab 10, made from a strip of a thin plastics film such as polyester or polypropylene, has a first segment 11, affixed to a diaper 12, and a second segment 11'. A portion 13 of the second segment is coated with a repositionable pressuresensitive adhesive, for example a styrene butadiene polymer tackified with natural resin esters. The distal portion 14 of the second segment 11' has no adhesive coating and serves as a pull tab for peeling portion 13 from the plastics film outer surface of the disposable diaper to undo a diaper closure.

The pressure-sensitive adhesive coating for use in the tape tab of the present invention must possess reasonable "quickstick" (as herein defined) without developing so much peel adhesion (as herein defined) as to rupture the plastics film diaper outer surface. The adhesive is desirable applied to the tab in the amount of 400800 grains per square meter.

In an ordinary quick-stick test, measuring the average force required to peel a 2" strip of tape away at right angles from a stainless steel surface, a tape tab typical of the present invention registered 18 oz./in. as compared to 56 oz./in. for a conventional diaper tape tab.

In a modified quick-stick test, the tapes were peeled away at right angles from an embossed matte plastics film manufactured by the Visqueen Division of the Ethyl Corporation. This film is one of the standard films used to form the outer surface of disposable diapers and is commonly referred to as having a matte type surface. When tested with reference to the matte finished surface, a tape tab typical of the present invention registered a 7 oz./in. quick-stick value compared to 20.5 oz./in, for the conventional tape tab. The tapes are, however, also repositionable with respect to non matte-type film surfaces.

In a tape tab according to the present invention, the adhesive coating is required to have a "quick stick" (as herein defined) of about 7 oz./in. with respect to the relevant plastics film outer surface. The quick stick value to which we refer in this connection is defined as the average force, in ounces per inch, required to peel the tape tab away at right angles from the relevant plastics film outer surface after being adhered to the latter by means of an applicator in the form of a roller. Although the present quick stick value is low, so that it contributes to the repositionability of the tape tab, the tape tab forms an adequate closure with the various plastics films currently available for use to form an outer surface of a diaper, and in particular with the matte type embossed film manufactured by the Ethyl Corporation.

In a peel adhesion test using a matte type embossed film to which a tape tab typical of the present invention had been adhered with the use of a 2 pound weight for 5 seconds, a low peel adhesion value of 8.3 oz./in. was obtained. This is less than the tearing strength of the thin plastics films ordinarily used on the outer surfaces of disposable diapers, and accordingly it does allow the tape tab to be separated from the film without tearing the film.

In a tape tab according to the present invention, the adhesive coating is required to have a "peel adhesion" (as herein defined) of substantially no more than 8.3 oz./in. with respect to the relevant plastics film outer surface. The peel adhesion value to which we refer in this connection is defined as the average force, in ounces per inch, required to peel the tape tab away at 1800 from the relevant plastics film outer surface after being positively adhered to the latter.

In the alternative construction shown in Figure 2, an end portion of the second segment of a tape tab is folded back on itself to form a pull tab 14. In the preferred embodiment shown in Figure 2, a nonadhesive portion 16 is provided between the first segment of the tape tab, which is affixed to a diaper 15, and the adhesive portion 13- of the second segment of the tape tab, forming a hinge.

The hinge affords a freely flexible portion of the tape between the two fastening ends of the tape, allowing movement between the two fastening ends and preventing the communication of lifting, peeling stresses to the two fastening ends. This is of significance in the present invention wherein the peeling strength of the tape has been reduced to achieve repositionability. If the thin plastics film tape material is elastic, greater movement is allowed between the tape fastening ends, giving added comfort to the wearer.

In laboratory tests, a paperbacked tape utilizing the same adhesive as the present invention, and having a hinge, was compared to the plastics film backed tape with hinge of the preferred embodiment of the present invention. The test devised was one believed to approximate the "in use" stresses on a diaper tape tab that would offer a comparison of the holding strength of various tape tabs. As both tapes posses adequate shear strength, the holding strength of the tape closure during lateral movement of the front and back portions of the diaper was compared. In each instance, the diaper closure was made by applying to the tape a pressure of five pounds for five minutes. The tapes were then compared for their ability to maintain a diaper closure and their ability to be separated from the diaper without tearing the plastics film outer surface. Each tape was subjected to oscillations at a right angle to the length of the tape. The tape fastening ends were disposed at a maximum distance from each other of 1+t in both directions. The plastics backed tape closure was able to sustain over 400 oscillations, whereas the paperbacked tape was able to sustain, at most, 73 oscillations.

The flexibility of the plastics film of tape tab 10, and its conformability to the plastics film outer surface of the conventional disposable diaper, provide a soft, smooth, supple tab fastening requiring considerably less adhesive than used in a conventional diaper tape tab.

As shown in Figure 2, the tape tab may optionally be affixed to a release portion 17 othe inside surface of the diaper 15 before use. Again, it may be provided with a removable cover strip, as is known in the art.

Figure 3 illustrates a diaper fastening made with the tape tab of the preferred embodiment of this invention, when adhesive portion 13 of the second segment of the tape tab is attached to the thin plastics outer surface 18 of the disposable diaper. Figure 3 shows the hinge-effect of the non-adhesive portion 16, allowing movement between the adhesive portion 13 of the second segment of the tape tab and the first segment 11, and providing a discontinuity of lifting, peeling forces therebetween.

Another advantage of the new tape tab of this invention is realized after the final opening of the diaper, when the diaper is ready to be discarded. The new tape tab allows the diaper to be opened cleanly, with no untidy tearing, while sufficient adhesive remains on the tape for one last function.

After the diaper is removed from the wearer, it may be folded or rolled and then sealed closed with the tape tabs so that the contents are contained securely within in order to be discarded.

WHAT WE CLAIM IS: 1. In combination, a disposable diaper of the type having an inside surface for direction toward a wearer and a thin, plastics film outer surface, and a repositionable tape tab comprising a strip of thin, flexible plastics film having a first segment affixed to the diaper, and a second segment, for attachment to the diaper outer surface in forming the closure, a portion of which is coated with a pressure-sensitive adhesive coating which is repositionable with respect to the plastics film outer surface and which has a "quick-stick" (as herein defined) of about 7 oz./in. and a "peel adhesion" (as herein defined) of substantially no more than 8.3 oz./in. with respect to the plastics film outer surface, the distal portion of the second segment being non-adhesive, forming a pull tab.

2. The combination of Claim 1, with a non-adhesive portion of the second segment lying adjacent the first segment.

3. The combination of Claim 1, wherein the strip of thin9 flexible plastics film is polypropylene.

4. The combination of Claim 2, wherein the thin, plastics film outer surface is a matte type embossed film.

5. The combination of Claim 2, wherein the adhesive coating is a styrene butadiene polymer tackified with natural resin esthers.

6. The combination of Claim 2, wherein the strip of thin, flexible plastics film is elastic.

7. The combination of Claim 2, wherein the strip of thin, flexible plastics film has a thickness of 4 mils or less.

8. As a component per se,a repositionable tape tab for a disposable diaper of the type having an inside surface for direction toward a wearer and a thin, plastics film outer surface, the tape tab comprising a strip of thin, flexible plastics film having a first segment capable of being affixed to the diaper, and a second segment, for attachment to the diaper outer surface in forming a closure, a portion of which is coated with a pressure-sensitive adhesive coating as specified in claim 1, the distal portion of the second segment being nonadhesive, forming a pull tab.

9. A tape tab as claimed in Claim 8, wherein a portion of the second segment lying adjacent the first segment is nonadhesive.

10. A tape tab as claimed in Claim 9, wherein the adhesive coating is a styrene butadiene polymer tackified with natural resin esters.

11. A tape tab as claimed in Claim 9, wherein the strip of thin, flexible plastics film is elastic.

12. A tape tab as claimed in Claim 9, wherein the strip of thin, flexible plastics film has a thickness of 4 mils or less.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (14)

**WARNING** start of CLMS field may overlap end of DESC **. of various tape tabs. As both tapes posses adequate shear strength, the holding strength of the tape closure during lateral movement of the front and back portions of the diaper was compared. In each instance, the diaper closure was made by applying to the tape a pressure of five pounds for five minutes. The tapes were then compared for their ability to maintain a diaper closure and their ability to be separated from the diaper without tearing the plastics film outer surface. Each tape was subjected to oscillations at a right angle to the length of the tape. The tape fastening ends were disposed at a maximum distance from each other of 1+t in both directions. The plastics backed tape closure was able to sustain over 400 oscillations, whereas the paperbacked tape was able to sustain, at most, 73 oscillations. The flexibility of the plastics film of tape tab 10, and its conformability to the plastics film outer surface of the conventional disposable diaper, provide a soft, smooth, supple tab fastening requiring considerably less adhesive than used in a conventional diaper tape tab. As shown in Figure 2, the tape tab may optionally be affixed to a release portion 17 othe inside surface of the diaper 15 before use. Again, it may be provided with a removable cover strip, as is known in the art. Figure 3 illustrates a diaper fastening made with the tape tab of the preferred embodiment of this invention, when adhesive portion 13 of the second segment of the tape tab is attached to the thin plastics outer surface 18 of the disposable diaper. Figure 3 shows the hinge-effect of the non-adhesive portion 16, allowing movement between the adhesive portion 13 of the second segment of the tape tab and the first segment 11, and providing a discontinuity of lifting, peeling forces therebetween. Another advantage of the new tape tab of this invention is realized after the final opening of the diaper, when the diaper is ready to be discarded. The new tape tab allows the diaper to be opened cleanly, with no untidy tearing, while sufficient adhesive remains on the tape for one last function. After the diaper is removed from the wearer, it may be folded or rolled and then sealed closed with the tape tabs so that the contents are contained securely within in order to be discarded. WHAT WE CLAIM IS:

1. In combination, a disposable diaper of the type having an inside surface for direction toward a wearer and a thin, plastics film outer surface, and a repositionable tape tab comprising a strip of thin, flexible plastics film having a first segment affixed to the diaper, and a second segment, for attachment to the diaper outer surface in forming the closure, a portion of which is coated with a pressure-sensitive adhesive coating which is repositionable with respect to the plastics film outer surface and which has a "quick-stick" (as herein defined) of about 7 oz./in. and a "peel adhesion" (as herein defined) of substantially no more than 8.3 oz./in. with respect to the plastics film outer surface, the distal portion of the second segment being non-adhesive, forming a pull tab.

2. The combination of Claim 1, with a non-adhesive portion of the second segment lying adjacent the first segment.

3. The combination of Claim 1, wherein the strip of thin9 flexible plastics film is polypropylene.

4. The combination of Claim 2, wherein the thin, plastics film outer surface is a matte type embossed film.

5. The combination of Claim 2, wherein the adhesive coating is a styrene butadiene polymer tackified with natural resin esthers.

6. The combination of Claim 2, wherein the strip of thin, flexible plastics film is elastic.

7. The combination of Claim 2, wherein the strip of thin, flexible plastics film has a thickness of 4 mils or less.

8. As a component per se,a repositionable tape tab for a disposable diaper of the type having an inside surface for direction toward a wearer and a thin, plastics film outer surface, the tape tab comprising a strip of thin, flexible plastics film having a first segment capable of being affixed to the diaper, and a second segment, for attachment to the diaper outer surface in forming a closure, a portion of which is coated with a pressure-sensitive adhesive coating as specified in claim 1, the distal portion of the second segment being nonadhesive, forming a pull tab.

9. A tape tab as claimed in Claim 8, wherein a portion of the second segment lying adjacent the first segment is nonadhesive.

10. A tape tab as claimed in Claim 9, wherein the adhesive coating is a styrene butadiene polymer tackified with natural resin esters.

11. A tape tab as claimed in Claim 9, wherein the strip of thin, flexible plastics film is elastic.

12. A tape tab as claimed in Claim 9, wherein the strip of thin, flexible plastics film has a thickness of 4 mils or less.

13. A tape tab as claimed in Claim 8,

wherein the strip of thin, flexible plastics film is polypropylene.

14. A combination comprising a disposable diaper and re-positionable tape tab, substantially as described and shown in the accompanying drawings.