Title:
SHORTENED SIDE FLAPS FOR DISPOSABLE DIAPER
United States Patent 3807402
Abstract:
A side flap attached to the lateral edge of a disposable diaper such that the distal edge of the side flap overlies but is not attached to the absorbent body (except at the ends of the side flap) and the distal edge of the side flap is shorter than the straight line drawn on the absorbent pad between the points of attachment at each end of the distal edge of the side flap such that a line of restraint is set up in each side flap when the diaper is opened and the side flap tends to be spaced from the top surface of the absorbent pad to provide an increased measure of protection against leg leakage by preventing free fluid from passing between the absorbent pad and the infant's leg along each lateral edge of a disposable diaper.
US Patent References:
FASTENING ARRANGEMENT FOR DISPOSABLE DIAPERS
Endres - December 1971 - 3630201
IMPROVED PRESSURE-SENSITIVE TAPE FASTENER FOR DISPOSABLE DIAPERS
Gellert - March 1972 - 3646937
DISPOSABLE DIAPER
Marsan - January 1973 - 3710797
Disposable prefolded diaper
Hrubecky - July 1965 - 3196874
FASTENING ARRANGEMENT FOR DISPOSABLE DIAPERS
Endres - December 1971 - 3630201
IMPROVED PRESSURE-SENSITIVE TAPE FASTENER FOR DISPOSABLE DIAPERS
Gellert - March 1972 - 3646937
DISPOSABLE DIAPER
Marsan - January 1973 - 3710797
Disposable prefolded diaper
Hrubecky - July 1965 - 3196874
Inventors:
Miller, Richard Chilton (Cincinnati, OH)
Duncan, Robert Campbell (Cincinnati, OH)
Duncan, Robert Campbell (Cincinnati, OH)
Application Number:
05/294739
Publication Date:
04/30/1974
Filing Date:
10/03/1972
View Patent Images:
Export Citation:
Assignee:
The Proctor & Gamble Company (Cincinnati, OH)
Primary Class:
Other Classes:
604/370
International Classes:
A61F13/15; A41B13/02
Field of Search:
128/284,287
Primary Examiner:
Rosenbaum, Charles F.
Attorney, Agent or Firm:
Braun V, Fredrick Gorman John Witte Richard H. C.
Claims:
What is claimed is
1. In a disposable diaper comprising an absorbent pad and an inwardly disposed, moisture impervious side flap overlying each lateral marginal area of the top surface of the absorbent pad, an improvement comprising:
2. The improvement of claim 1 wherein the diaper includes a moisture impervious back sheet being greater in width than the pad, the pad being superposed and centered on the back sheet whereby side portions of the back sheet are not covered by the pad, and said side portions are folded upwardly and inwardly around the edges of the pad to overlie the side marginal areas of the pad and form the side flaps.
3. The improvement of claim 2 wherein the line of attachment is between the bottom surface of said absorbent pad and said back sheet.
4. The improvement of claim 2 wherein said line of attachment is between the top surface of said absorbent pad and said side flaps.
5. The improvement of claim 4 wherein the anterior and posterior ends of the distal edge of the side flap are attached to the top surface of the absorbent pad.
6. In a disposable diaper structure comprising an absorbent pad of substantially rectangular lineaments and a moisture impervious back sheet being greater in width than the absorbent pad, the pad being superposed and centered on the back sheet whereby side portions of the back sheet are not covered by the pad, the side portions of said back sheet being folded upwardly and inwardly around the edges of the pad to overlie the side marginal areas of the pad to form side flaps, an improvement comprising:
7. The improvement of claim 6 wherein the anterior and posterior ends of the distal edge of the side flap are attached to the top surface of the absorbent pad.
8. A disposable diaper, comprising:
1. In a disposable diaper comprising an absorbent pad and an inwardly disposed, moisture impervious side flap overlying each lateral marginal area of the top surface of the absorbent pad, an improvement comprising:
2. The improvement of claim 1 wherein the diaper includes a moisture impervious back sheet being greater in width than the pad, the pad being superposed and centered on the back sheet whereby side portions of the back sheet are not covered by the pad, and said side portions are folded upwardly and inwardly around the edges of the pad to overlie the side marginal areas of the pad and form the side flaps.
3. The improvement of claim 2 wherein the line of attachment is between the bottom surface of said absorbent pad and said back sheet.
4. The improvement of claim 2 wherein said line of attachment is between the top surface of said absorbent pad and said side flaps.
5. The improvement of claim 4 wherein the anterior and posterior ends of the distal edge of the side flap are attached to the top surface of the absorbent pad.
6. In a disposable diaper structure comprising an absorbent pad of substantially rectangular lineaments and a moisture impervious back sheet being greater in width than the absorbent pad, the pad being superposed and centered on the back sheet whereby side portions of the back sheet are not covered by the pad, the side portions of said back sheet being folded upwardly and inwardly around the edges of the pad to overlie the side marginal areas of the pad to form side flaps, an improvement comprising:
7. The improvement of claim 6 wherein the anterior and posterior ends of the distal edge of the side flap are attached to the top surface of the absorbent pad.
8. A disposable diaper, comprising:
Description:
FIELD OF THE INVENTION
This invention relates generally to disposable diapers designed to receive and retain the natural discharge of babies.
DESCRIPTION OF THE PRIOR ART
Disposable diapers heretofore have been made both with and without side flaps. Disposable diapers without side flaps have no means (1) to prevent wicking from an edge of the diaper to adjacent clothing or (2) to prevent free fluids, i.e., fluids between the infant's skin and the absorbent pad such that they are not held within the absorbent pad, from bypassing between the absorbent pad and an infant's leg to adjacent clothing.
Some disposable diapers, such as those disclosed in U.S. Pat. No. 3,196,874, issued to F. J. Hrubecky on July 27, 1965 and U.S. Pat. No. Re26,151, issued to R. C. Duncan et al. on Jan. 31, 1967, have side flaps incorporated therein, said side flaps generally being an extension of a fluid impervious back sheet which is folded around the lateral edges of and onto the top surface of the absorbent pad. These side flaps prove effective generally to prevent wicking and overflow from a fluid laden absorbent pad to clothing contacting the lateral edge of the diaper in that the side flap presents a fluid impervious barrier between the edge of the absorbent pad and the contacting clothing and in addition, provides a gasketing action about the legs of the baby. Despite the effectiveness of such prior art structures, however, free fluids occasionally can leak through the leg openings and thus bypass the diaper.
Reusable cloth diapers have been taught which incorporate outwardly extending portions; said portions can be drawn tight about the baby's thigh, e.g., U.S. Pat. Nos. 3,417,751, issued to I. L. Murdoch on Dec. 24, 1968; 2,969,065, issued to D. A. Farnsworth on Jan. 24, 1961; and 2,827,052, issued to M. Goodman et al. on Mar. 18, 1958. The outwardly extending portions on these diapers are secured around a baby's thigh. However, these portions are not inwardly directed, water impervious, or a structure on a disposable diaper, and thus they do not solve the problems of bypass and wicking in a disposable diaper.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a water impervious member to assure filling of the gap occurring between the absorbent body of a disposable diaper and an infant's thigh when the infant is diapered.
It is another object of this invention to provide a disposable diaper having a water impervious member which rises from the top surface of the absorbent pad to provide a dam to contain free fluids within the confines of the diaper.
It is a further object of this invention to provide a disposable diaper having a water impervious side flap which is attached to a lateral edge of the diaper and which raised from the top surface of the absorbent pad.
It is also an object of this invention to provide a water impervious side flap for a disposable diaper, the side flap being attached to a water impervious back sheet and raised above the top surface of the absorbent body of the disposable diaper when the diaper is fitted to an infant such that it reduces the gap between the top surface of the absorbent body and the infant's thigh and thus reduces bypass in this area.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an improvement for a disposable diaper having an absorbent pad, a moisture impervious back sheet underlying the absorbent pad, and an inwardly disposed moisture repellent side flap overlying each lateral marginal area of the top surface of the absorbent pad, wherein the improvement comprises: each side flap being attached to the absorbent pad along a line of attachment and the line of attachment being adjacent the lateral edge of the absorbent pad whereby the distal edge of the side flap is free of attachment to the absorbent pad, the length of the distal edge of the side flap being shorter than the length of the projection of that distal edge as it is projected onto the top surface of the absorbent pad when the absorbent pad is in an end-supported flattened condition, whereby a line of restraint is set up in each side flap in an end-supported flattened condition so that each side flap tends to be spaced from the top surface of the absorbent pad.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following descriptions which are taken in connection with the accompanying drawings, in which the thickness of some of the materials are exaggerated for clarity and in which:
FIG. 1 is a plan view, partially cut away, of a diaper prior to folding and having side flaps of this invention;
FIG. 2 is a perspective view of a diaper similar to that of FIG. 1 partially cut away after it has been folded and the side flaps shortened.
FIG. 3 is a partial cross sectional view of the diaper of FIG. 2 taken along line 3--3 of FIG. 2;
FIG. 4 is a plan view of another form of diaper prior to folding which will have shortened side flaps of this invention;
FIG. 5 is a perspective view illustrating the diaper of FIG. 4 as folded;
FIG. 6 is a partial cross section along line 6--6 of FIG. 5;
FIG. 7 is a partial cross section similar to that of FIG. 6 and illustrating an alternate embodiment of the attachment of the shortened side flap;
FIG. 8 is a plan view, partially cut away of an alternate diaper before folding and shortening of the side flaps;
FIG. 9 is a perspective view of the diaper of FIG. 8 as folded and having shortened side flaps;
FIG. 10 illustrates in cross section the diaper of FIG. 5 when worn by a baby.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown a plan view of a disposable diaper of this invention before the side flaps are shortened. The diaper as shown in FIG. 1 can be formed in accordance with the teachings of U.S. Pat. No. Re26,151, issued to R. C. Duncan et al. on Jan. 31, 1967, incorporated herein by reference. The diaper has an absorbent pad 24 backed by a moisture impervious back sheet 23. Absorbent pad 24 can have an absorbent body 21 superposed by a top sheet 22, the top sheet 22 providing a barrier between the absorbent body 21 and a baby's skin. Back sheet 23 is larger, at least in width, than the absorbent pad 24 to provide side flaps 25 which are folded over and onto the top surface of the absorbent pad 24 whereby the side flaps 25 overlie the lateral marginal area of the top surface of the absorbent pad 24. The absorbent pad 24 is attached to the back sheet 23 by a line of attachment 29 between the bottom surface of the absorbent pad 24 and the back sheet 23 adjacent to each lateral edge of the diaper. The line of attachment 29 in this embodiment extends along and substantially parallel to the lateral edges of the diaper. The side flap 25 on each side of the diaper thus is attached along a line of attachment 29 to the lateral edge of the absorbent pad 24 and that portion of the side flaps 25 lying inwardly from the extreme side edge of the absorbent pad is free of attachment to the absorbent pad 24. Thus side flap 25 has a distal edge 30 which lies inwardly from the edge of the absorbent pad 24 and is essentially free of attachment to absorbent pad 24. In the preferred embodiment, each end, i.e., both the anterior and posterior ends, of the distal edge 30 are attached to the top surface of absorbent pad 24 by a flap-end adhesive means 32, but the advantages of this invention can also be realized if the flap-end adhesive means 32 is eliminated from the diaper.
The side flap 25 should have a minimum width of about three-eighths inch and preferably about three-fourths inch. The minimum width is necessary to achieve an effective shortened side flap.
The line of attachment 29 alternatively can be between the contacting surfaces of the side flap 25 and the top surface of the absorbent pad 24 along the side edge 33 of the absorbent pad 24 as is shown in FIG. 2.
The back sheet 23 preferably is a flexible waterproof web, e.g., a 0.001 inch thick, low density, pattern embossed, opaque polyethylene web.
The diaper of FIG. 1 is folded to the configuration of FIG. 2 along infold lines 26, outfold lines 27, and infold line 46. "Infold" is used herein to denote that the top surface areas of the absorbent pad 24 lying on either side of the fold line are brought together and put in surface contact when the fold is made. "Outfold" is used herein to denote that the surface areas of the back sheet 23 lying on either side of the fold line are brought together and put in surface contact when the fold is made. Infolds 26 and outfolds 27 are made prior to infold 46. Also fold maintaining glue spots 28 maintain the infold 26 at the longitudinal center of the pad so that the Z-fold configuration is maintained in the crotch area of the diaper while the diaper is being worn.
The diaper of FIG. 2 is shown in an end-supported flattened condition, i.e., the center fold 46 is allowed to unfold and the ends of the diaper are supported by the shortened side flap 25. Side flap 25 is shortened to the extent that the length of the distal edge 30 of the side flap is shorter than the projection 38 of the distal edge 30 onto the top surface of the absorbent pad 24 immediately below it. In other words, the distal edge 30 is shorter than the length of the absorbent pad immediately beneath the distal edge 30 and thus a line of restraint is set up in each side flap 25 supporting the ends of the diaper when the center fold 46 is unfolded.
The side flap 25, instead of being an extension of the back sheet 23, can also be a sheet of water impervious material, for example, polyethylene film, separately formed and subsequently attached to the back sheet 23 or the top surface of the absorbent pad 24. FIG. 7 shows in detail for another embodiment a separately formed side flap attached to the back sheet.
The side flap 25 can be shortened for a diaper of the embodiment shown in FIG. 2 by making the distal edge 30 shorter than the length of the side flap 25 along the line of attachment 29. This shortening can be effected by putting a triangular pleat 47 in the side flap 25 whereby the distal edge 30 is shortened more than the the side flap edge adjacent the side edge 33 of the absorbent pad 24 (hereinafter referred to as the proximal edge of the side flap 25). The pleat 47 is then secured by any of the holding means well known to those of ordinary skill in the art, such as adhesives or heat sealing. Of course, the triangular section could also be cut out of the side flap 25 and the cut edges of the side flaps brought together to form a butt or lap joint.
The side flap 25 can also be shortened by shrinking the distal edge 30 thereof. This shrinking can be accomplished, for example, on a polyethylene film, by heating the distal edge 30. Polyethylene film is stressed along its length during its processing. Heating the stressed polyethylene will release the internal stresses therein and promote a reduction in length along the heated area. It has been found that heating the distal edge 30 with an element at 230° F. for periods of time short enough such that the polyethylene does not melt is sufficient to cause a shortening of the distal edge 30.
The side flap 25 can also be effectively shortened by attaching a point near each end of the distal edge 30 to the absorbent pad 24 at a position inwardly from the position of each point on the absorbent pad when the side flaps are not shortened. This in effect makes the distal edge 30 shorter than the length of the absorbent pad underlying the distal edge 30.
The shortening of the side flap 25 is preferably uniformly distributed along the length of the side flap such as is done when a stressed polyethylene side flap is heated to relieve internal stresses. A uniform distribution of the shortening in the side flap 15 is advantageous because each increment of length of the side flap 25 is shortened a proportional amount of the overall shortening and undue distortion of the side flap 25 in any one area is avoided.
The distal edge 30 of the side flap 25 should be from about 2 percent to about 10 percent shorter than the proximal edge of the side flap 25 along the effective length of the side flap, preferably from about 4 percent to about 10 percent. The effective length of the side flap varies in accordance with the specific embodiment. For example, if the ends of the distal edge 30 are attached to the top surface of absorbent pad 24 by the flap-end adhesive means 32 as shown in FIG. 2, the effective length of the side flap 25 is the length of the side flap 25 between the flap-end adhesive means 32 at the opposite ends, i.e., the anterior and posterior ends, of the side flap 25; whereas if the flap-end adhesive means 32 is not used, whereby the ends of the distal edge 30 are free of attachment to the top surface of the absorbent pad 24, the effective length of the side flap 25 is the actual length thereof. The distal edge 30 should be a minimum of about 2 percent shorter in order to achieve some spacing of the distal edge 30 from the top surface of the absorbent pad 24. The maximum of about 10 percent shortening is desired to insure that the shortened side flap 25 is inwardly directed as shown in FIG. 3, or in other words, to prevent the side flap 25 from forming an obtuse angle with the top surface of the absorbent pad 24 when the diaper is in its end supported position.
The cross section in FIG. 3 displays more vividly the effect of the shortened side flaps wherein the distal end 30 is spaced from the top sheet 22 to provide a constraining dam for free fluid flowing along top sheet 22. Free fluid on the top sheet 22 is most probable when the top sheet 22 has a poor "strikethrough" property, i.e., when fluid penetration of the top sheet 22 is retarded. The dam created by the distal edge 30 being spaced from the top sheet 22 is also advantageous when the top sheet 22 has good "strikethrough" because the side flap will prevent bypass of gushing fluids which can occur at the time a baby urinates. The damming effect created by a shortened side flap has been found advantageous in diapers wherein the "strikethrough" of the top sheet 22, as measured by percent of water which runs off a sheet inclined 5°, is as low as zero percent.
The runoff test as used to measure strikethrough comprises clamping a preweighed sample consisting of the fabric to be tested backed by a suitable absorbing medium, e.g., cellulose wadding or airfelt, on a flat sheet, e.g., plexiglass or metal; positioning the sheet at some desired inclination angle to the horizon; metering a 50 milliliter quantity of water, which weighs about 48 grams, onto the sample at a spot 9 inches from the lower edge of the sample at a rate of approximately 5 milliliters per second; and weighing the wetted sample and deducting the tare of the sample to determine the approximate weight of water absorbed by the sample. The percent runoff is then determined as follows: ##SPC1##
When measured in terms of percent runoff, a strikethrough stated as a "low" percent indicates rapid penetration of the sheet by the water whereas a strikethrough stated as a "high" percent indicates a slow penetration of the sheet by the water.
Two types of top sheets, i.e., a "standard" and a "quick strikethrough" (QS) top sheet, were used in diapers having shortened side flaps and improved containment as measured by leg leakage of the diapers was achieved with both of the top sheets as compared to similar diapers with the same top sheet but not having the shortened side flaps. The standard top sheet was a print bonded rayon non-woven fabric having a basis weight of 18 to 19 grams per square yard. The rayon used was 11/2 denier, 11/8 inch staple in the form of a carded web. The bonding agent used was Rohm and Haas Rhoplex, HA-8. The standard top sheet is available from Kendall Co., Fiber Products Division, Walpole, Mass. 02081 under their designation, Webline, F6211. The runoff of water for the standard top sheet was 30 percent when the sheet was inclined 5° and 75 percent when the sheet was inclined 20°. The QS top sheet was the same as the standard except that a different bonding agent, which is not known to applicants at this time, was used. The QS top sheet is also available from Kendall Co. and is identified by Kendall Co. as SW 269-3. The runoff of water for the QS top sheet was zero percent when the sheet was inclined 5° and 3.0 percent when the sheet was inclined 20°.
FIGS. 4 and 5 show a diaper of another shape incorporating the shortened side flaps of this invention. The absorbent pad 49 of this diaper has essentially an hourglass outline or lineaments wherein 34 is the anterior end of the pad, 35 is the posterior end of the pad and the side edges 48 of the pad are curved inwardly from a rectangular pattern. The absorbent pad 49 can be constructed as described previously wherein it has an absorbent body and a top sheet. The back sheet 50 underlies the absorbent pad and has a substantially rectangualr periphery about as wide as the anterior and posterior ends of the absorbent pad 49. The diaper of FIG. 5 was formed from the pad of FIG. 4 by folding the absorbent pad 49 and the portion of the back sheet 50 underlying the absorbent pad 49 in accordance with the teachings of the commonly owned copending U.S. application Ser. No. 119,420, filed Feb. 26, 1971, entitled DISPOSABLE DIAPER, now U.S. Pat. No. 3,710,797, incorporated herein by reference, and by folding the side flaps 25, i.e., the portions of the back sheet 50 not covered by the absorbent pad 49 due to the hourlgass shape of the pad 49, over and onto the top surface of the absorbent pad 49 with side flap outfolds 69 and 70 extending from end point 65 to external point 54 and from end point 66 to external point 55, respectively. The side fold glue spots 36 are an adhesive means to maintain the infolds 26 while the diaper is worn, and the lines of attachment 29 are on the top surface of absorbent pad 29.
The fold pattern taught by the above mentioned application Ser. No. 119,420 is as follows: A composite central fold 71 is provided extending from the end point 65 to the end point 66. The central fold 71 separates the entire diaper into approximately equal portions, i.e., an anterior and a posterior portion. The central fold 71 includes a central infold 56 extending between the inner point 57 and the inner point 58. Intermediate outfolds 59 and 60 are provided extending outwardly from the inner points 57 and 58, respectively, to the intermediate points 61 and 62, respectively. The outer infolds 63 and 64 extend to the end points 65 and 66, respectively, from the intermediate points 61 and 62, respectively.
Posterior joinder points 51 and 51' and anterior joinder points 52 and 52' are provided as convergence points for additional infolds and outfolds along the side edges of the diaper preferably so that each joinder point is further from the central fold 71 than it is from its nearest anterior or posterior end 34 or 35. Each of the joinder points 51, 51', 52 and 52' preferably lies at about the same distance from the central fold 71. Extending from the joinder points are the infolds 26. The pair of infolds 26 on the left side of the diaper merge at the inner point 58 and the pair of infolds in the right side of the diaper merge at the inner point 57. Similarly, the pair of outfolds 27 on the left side extend from the joinder points 51 and 52 to the intermediate point 61 and the pair of outfolds 27 on the right side extend from the joinder points 52 and 52' to the intermediate point 62.
With the above combination of infolds and outfolds, the diaper of FIG. 4 is readily folded on itself during which manipulation it passes through the configuration illustrated in FIG. 5. This is accomplished by merely bringing the ends of the pad 34 and 35 together so that the central infold 56 in effect functions as a hinge point. In the course of the folding sequence, the inner triangular areas 67 fold inwardly (see FIG. 2) against the areas of the top surface of the absorbent pad 49 which adjoin the infolds 26. Similarly, the outer triangular areas 68 formed on either side of the outer infolds 63 and 64 fold together in pairs as a result of the outfolds 27. Thus, when the diaper is folded in half a full double gusset fold is formed at each side of the diaper by the triangular areas 67 and 68.
The distal edge 30 of the side flap 25 in the diaper of FIG. 5 in its end-supported flattened condition is shorter than the projection 38 of the distal edge 30 on the top surface of the absorbent pad 49. The shortening of the side flap 25 spaces the distal edge 30 from the top surface of the absorbent pad 49 as is shown in FIG. 5. The fact that the distal edge 30 is shorter than its projection on the top surface of the absorbent pad 49 is readily apparent from FIG. 4 by noticing that the distal edge 30 is the shortest distance between the posterior joinder 51 and the anterior joinder 52 of the fold lines 26 and 27, whereas the projection 38 of the distal edge 30 when the absorbent pad is in the end-supported flattened condition lies within the area between outfold 27 and the side edge 48 of the absorbent pad 49.
FIG. 6 being a cross section through FIG. 5 illustrates the spacing of the distal end 30 from the top surface of the absorbent pad 49 whereby the side flap creates a dam to prevent fluid bypass. FIG. 6 also shows more detail of the diaper structure wherein the side flap 25 is a marginal portion of the back sheet 50. The absorbent pad 49 is shown having an absorbent body 21 and a top sheet 22. The top sheet 22 is secured to the bottom side of the absorbent body 21 by a glue line 39 extending along and adjacent to the side edge of the absorbent body 21. The side flap 25/back sheet 50 is attached to the top surface of the absorbent pad by a line of attachment 29 which is an adhesive means extending along and adjacent to the side edge 48 of the absorbent pad.
FIG. 7 illustrates an alternate construction of a side flap for a diaper as shown in FIG. 5. The back sheet 50 is trimmed to essentially coincide with the side edge 48 of the absorbent pad and is attached to the bottom of the absorbent pad by adhesive means, such as hot melt glue 72. The side flap 25 is separately formed and secured to the back sheet 50 by the line of attachment 29.
The diapers illustrated in FIGS. 8 and 9 are another embodiment of a diaper having shortened side flaps. The unfolded diaper shown in FIG. 8 is formed like the unfolded diaper of FIG 1 but folded in accordance with the teachings of the previously mentioned U.S. application, Ser. No. 119,420. The line of attachment 29 is between the top surface of the absorbent pad 53 and the side flaps 25, and the line of attachment 29 is along and adjacent to the side edge of the absorbent pad 53. The diaper of FIGS. 8 and 9 also can have the side fold glue spot 36 to maintain the infolds 26 during a wearing of the diaper. Fold line 27 is again an outfold and center fold 46 is an infold.
In the embodiment of FIGS. 8 and 9, the side flap 25 is shortened as described in conjunction with FIGS. 1 and 2, i.e., making the distal edge 30 shorter than the length of the side flap along the line of attachment 29. As mentioned above, a triangular pleat in the side flap 25, heating the distal edge 30 of a side flap material having therein internal stresses, or attaching points on the distal edge 30 endwardly from their normal location on the absorbent pad will provide a side flap wherein the distal edge 30 is shorter than its projection on the top surface of the absorbent pad when the pad is in an end-supported condition.
Attaching the distal edge 30 of the side flaps 25 at the top surface of the absorbent pad 53 adjacent the intersections 40 of the distal edge 30 and the outfolds 27 maintains the side flaps over the top surface of the pad 49 to make an easier-to-handle diaper. Although it is preferred that the distal edge 30 of the side flap 25 be attached to the top surface of the absorbent pad 53 at the intersection 40, it is not absolutely necessary to do so to acquire an effective shortened side flap.
The shortness of the distal edge 30 insures that the first line of restraint in an open diaper will be in the side flap 25 and essentially along the distal edge 30. Thus when a diaper is in the "worn" configuration as shown in FIG. 10, the distal edge 30 of the side flap 25 is spaced from the absorbent pad to contact an infant's thigh 41 and prevent bypass between the thigh 41 and the outer portion 45 of the absorbent pad 49 of the diaper. This gives both better containment and more comfort to the infant because the portion close to his thigh is a flexible member which will follow the infant's movement more easily than a thick walled absorbent pad. Also, the flexible side flaps 25 will not bind or restrict movement of an infant's thigh. The diaper in FIG. 10 is numbered to correspond to that of FIG. 9.
Thus it is apparent that there has been provided, in accordance with the invention, an improvement for disposable diapers that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and broad scope of the appended claims.
This invention relates generally to disposable diapers designed to receive and retain the natural discharge of babies.
DESCRIPTION OF THE PRIOR ART
Disposable diapers heretofore have been made both with and without side flaps. Disposable diapers without side flaps have no means (1) to prevent wicking from an edge of the diaper to adjacent clothing or (2) to prevent free fluids, i.e., fluids between the infant's skin and the absorbent pad such that they are not held within the absorbent pad, from bypassing between the absorbent pad and an infant's leg to adjacent clothing.
Some disposable diapers, such as those disclosed in U.S. Pat. No. 3,196,874, issued to F. J. Hrubecky on July 27, 1965 and U.S. Pat. No. Re26,151, issued to R. C. Duncan et al. on Jan. 31, 1967, have side flaps incorporated therein, said side flaps generally being an extension of a fluid impervious back sheet which is folded around the lateral edges of and onto the top surface of the absorbent pad. These side flaps prove effective generally to prevent wicking and overflow from a fluid laden absorbent pad to clothing contacting the lateral edge of the diaper in that the side flap presents a fluid impervious barrier between the edge of the absorbent pad and the contacting clothing and in addition, provides a gasketing action about the legs of the baby. Despite the effectiveness of such prior art structures, however, free fluids occasionally can leak through the leg openings and thus bypass the diaper.
Reusable cloth diapers have been taught which incorporate outwardly extending portions; said portions can be drawn tight about the baby's thigh, e.g., U.S. Pat. Nos. 3,417,751, issued to I. L. Murdoch on Dec. 24, 1968; 2,969,065, issued to D. A. Farnsworth on Jan. 24, 1961; and 2,827,052, issued to M. Goodman et al. on Mar. 18, 1958. The outwardly extending portions on these diapers are secured around a baby's thigh. However, these portions are not inwardly directed, water impervious, or a structure on a disposable diaper, and thus they do not solve the problems of bypass and wicking in a disposable diaper.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a water impervious member to assure filling of the gap occurring between the absorbent body of a disposable diaper and an infant's thigh when the infant is diapered.
It is another object of this invention to provide a disposable diaper having a water impervious member which rises from the top surface of the absorbent pad to provide a dam to contain free fluids within the confines of the diaper.
It is a further object of this invention to provide a disposable diaper having a water impervious side flap which is attached to a lateral edge of the diaper and which raised from the top surface of the absorbent pad.
It is also an object of this invention to provide a water impervious side flap for a disposable diaper, the side flap being attached to a water impervious back sheet and raised above the top surface of the absorbent body of the disposable diaper when the diaper is fitted to an infant such that it reduces the gap between the top surface of the absorbent body and the infant's thigh and thus reduces bypass in this area.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an improvement for a disposable diaper having an absorbent pad, a moisture impervious back sheet underlying the absorbent pad, and an inwardly disposed moisture repellent side flap overlying each lateral marginal area of the top surface of the absorbent pad, wherein the improvement comprises: each side flap being attached to the absorbent pad along a line of attachment and the line of attachment being adjacent the lateral edge of the absorbent pad whereby the distal edge of the side flap is free of attachment to the absorbent pad, the length of the distal edge of the side flap being shorter than the length of the projection of that distal edge as it is projected onto the top surface of the absorbent pad when the absorbent pad is in an end-supported flattened condition, whereby a line of restraint is set up in each side flap in an end-supported flattened condition so that each side flap tends to be spaced from the top surface of the absorbent pad.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following descriptions which are taken in connection with the accompanying drawings, in which the thickness of some of the materials are exaggerated for clarity and in which:
FIG. 1 is a plan view, partially cut away, of a diaper prior to folding and having side flaps of this invention;
FIG. 2 is a perspective view of a diaper similar to that of FIG. 1 partially cut away after it has been folded and the side flaps shortened.
FIG. 3 is a partial cross sectional view of the diaper of FIG. 2 taken along line 3--3 of FIG. 2;
FIG. 4 is a plan view of another form of diaper prior to folding which will have shortened side flaps of this invention;
FIG. 5 is a perspective view illustrating the diaper of FIG. 4 as folded;
FIG. 6 is a partial cross section along line 6--6 of FIG. 5;
FIG. 7 is a partial cross section similar to that of FIG. 6 and illustrating an alternate embodiment of the attachment of the shortened side flap;
FIG. 8 is a plan view, partially cut away of an alternate diaper before folding and shortening of the side flaps;
FIG. 9 is a perspective view of the diaper of FIG. 8 as folded and having shortened side flaps;
FIG. 10 illustrates in cross section the diaper of FIG. 5 when worn by a baby.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown a plan view of a disposable diaper of this invention before the side flaps are shortened. The diaper as shown in FIG. 1 can be formed in accordance with the teachings of U.S. Pat. No. Re26,151, issued to R. C. Duncan et al. on Jan. 31, 1967, incorporated herein by reference. The diaper has an absorbent pad 24 backed by a moisture impervious back sheet 23. Absorbent pad 24 can have an absorbent body 21 superposed by a top sheet 22, the top sheet 22 providing a barrier between the absorbent body 21 and a baby's skin. Back sheet 23 is larger, at least in width, than the absorbent pad 24 to provide side flaps 25 which are folded over and onto the top surface of the absorbent pad 24 whereby the side flaps 25 overlie the lateral marginal area of the top surface of the absorbent pad 24. The absorbent pad 24 is attached to the back sheet 23 by a line of attachment 29 between the bottom surface of the absorbent pad 24 and the back sheet 23 adjacent to each lateral edge of the diaper. The line of attachment 29 in this embodiment extends along and substantially parallel to the lateral edges of the diaper. The side flap 25 on each side of the diaper thus is attached along a line of attachment 29 to the lateral edge of the absorbent pad 24 and that portion of the side flaps 25 lying inwardly from the extreme side edge of the absorbent pad is free of attachment to the absorbent pad 24. Thus side flap 25 has a distal edge 30 which lies inwardly from the edge of the absorbent pad 24 and is essentially free of attachment to absorbent pad 24. In the preferred embodiment, each end, i.e., both the anterior and posterior ends, of the distal edge 30 are attached to the top surface of absorbent pad 24 by a flap-end adhesive means 32, but the advantages of this invention can also be realized if the flap-end adhesive means 32 is eliminated from the diaper.
The side flap 25 should have a minimum width of about three-eighths inch and preferably about three-fourths inch. The minimum width is necessary to achieve an effective shortened side flap.
The line of attachment 29 alternatively can be between the contacting surfaces of the side flap 25 and the top surface of the absorbent pad 24 along the side edge 33 of the absorbent pad 24 as is shown in FIG. 2.
The back sheet 23 preferably is a flexible waterproof web, e.g., a 0.001 inch thick, low density, pattern embossed, opaque polyethylene web.
The diaper of FIG. 1 is folded to the configuration of FIG. 2 along infold lines 26, outfold lines 27, and infold line 46. "Infold" is used herein to denote that the top surface areas of the absorbent pad 24 lying on either side of the fold line are brought together and put in surface contact when the fold is made. "Outfold" is used herein to denote that the surface areas of the back sheet 23 lying on either side of the fold line are brought together and put in surface contact when the fold is made. Infolds 26 and outfolds 27 are made prior to infold 46. Also fold maintaining glue spots 28 maintain the infold 26 at the longitudinal center of the pad so that the Z-fold configuration is maintained in the crotch area of the diaper while the diaper is being worn.
The diaper of FIG. 2 is shown in an end-supported flattened condition, i.e., the center fold 46 is allowed to unfold and the ends of the diaper are supported by the shortened side flap 25. Side flap 25 is shortened to the extent that the length of the distal edge 30 of the side flap is shorter than the projection 38 of the distal edge 30 onto the top surface of the absorbent pad 24 immediately below it. In other words, the distal edge 30 is shorter than the length of the absorbent pad immediately beneath the distal edge 30 and thus a line of restraint is set up in each side flap 25 supporting the ends of the diaper when the center fold 46 is unfolded.
The side flap 25, instead of being an extension of the back sheet 23, can also be a sheet of water impervious material, for example, polyethylene film, separately formed and subsequently attached to the back sheet 23 or the top surface of the absorbent pad 24. FIG. 7 shows in detail for another embodiment a separately formed side flap attached to the back sheet.
The side flap 25 can be shortened for a diaper of the embodiment shown in FIG. 2 by making the distal edge 30 shorter than the length of the side flap 25 along the line of attachment 29. This shortening can be effected by putting a triangular pleat 47 in the side flap 25 whereby the distal edge 30 is shortened more than the the side flap edge adjacent the side edge 33 of the absorbent pad 24 (hereinafter referred to as the proximal edge of the side flap 25). The pleat 47 is then secured by any of the holding means well known to those of ordinary skill in the art, such as adhesives or heat sealing. Of course, the triangular section could also be cut out of the side flap 25 and the cut edges of the side flaps brought together to form a butt or lap joint.
The side flap 25 can also be shortened by shrinking the distal edge 30 thereof. This shrinking can be accomplished, for example, on a polyethylene film, by heating the distal edge 30. Polyethylene film is stressed along its length during its processing. Heating the stressed polyethylene will release the internal stresses therein and promote a reduction in length along the heated area. It has been found that heating the distal edge 30 with an element at 230° F. for periods of time short enough such that the polyethylene does not melt is sufficient to cause a shortening of the distal edge 30.
The side flap 25 can also be effectively shortened by attaching a point near each end of the distal edge 30 to the absorbent pad 24 at a position inwardly from the position of each point on the absorbent pad when the side flaps are not shortened. This in effect makes the distal edge 30 shorter than the length of the absorbent pad underlying the distal edge 30.
The shortening of the side flap 25 is preferably uniformly distributed along the length of the side flap such as is done when a stressed polyethylene side flap is heated to relieve internal stresses. A uniform distribution of the shortening in the side flap 15 is advantageous because each increment of length of the side flap 25 is shortened a proportional amount of the overall shortening and undue distortion of the side flap 25 in any one area is avoided.
The distal edge 30 of the side flap 25 should be from about 2 percent to about 10 percent shorter than the proximal edge of the side flap 25 along the effective length of the side flap, preferably from about 4 percent to about 10 percent. The effective length of the side flap varies in accordance with the specific embodiment. For example, if the ends of the distal edge 30 are attached to the top surface of absorbent pad 24 by the flap-end adhesive means 32 as shown in FIG. 2, the effective length of the side flap 25 is the length of the side flap 25 between the flap-end adhesive means 32 at the opposite ends, i.e., the anterior and posterior ends, of the side flap 25; whereas if the flap-end adhesive means 32 is not used, whereby the ends of the distal edge 30 are free of attachment to the top surface of the absorbent pad 24, the effective length of the side flap 25 is the actual length thereof. The distal edge 30 should be a minimum of about 2 percent shorter in order to achieve some spacing of the distal edge 30 from the top surface of the absorbent pad 24. The maximum of about 10 percent shortening is desired to insure that the shortened side flap 25 is inwardly directed as shown in FIG. 3, or in other words, to prevent the side flap 25 from forming an obtuse angle with the top surface of the absorbent pad 24 when the diaper is in its end supported position.
The cross section in FIG. 3 displays more vividly the effect of the shortened side flaps wherein the distal end 30 is spaced from the top sheet 22 to provide a constraining dam for free fluid flowing along top sheet 22. Free fluid on the top sheet 22 is most probable when the top sheet 22 has a poor "strikethrough" property, i.e., when fluid penetration of the top sheet 22 is retarded. The dam created by the distal edge 30 being spaced from the top sheet 22 is also advantageous when the top sheet 22 has good "strikethrough" because the side flap will prevent bypass of gushing fluids which can occur at the time a baby urinates. The damming effect created by a shortened side flap has been found advantageous in diapers wherein the "strikethrough" of the top sheet 22, as measured by percent of water which runs off a sheet inclined 5°, is as low as zero percent.
The runoff test as used to measure strikethrough comprises clamping a preweighed sample consisting of the fabric to be tested backed by a suitable absorbing medium, e.g., cellulose wadding or airfelt, on a flat sheet, e.g., plexiglass or metal; positioning the sheet at some desired inclination angle to the horizon; metering a 50 milliliter quantity of water, which weighs about 48 grams, onto the sample at a spot 9 inches from the lower edge of the sample at a rate of approximately 5 milliliters per second; and weighing the wetted sample and deducting the tare of the sample to determine the approximate weight of water absorbed by the sample. The percent runoff is then determined as follows: ##SPC1##
When measured in terms of percent runoff, a strikethrough stated as a "low" percent indicates rapid penetration of the sheet by the water whereas a strikethrough stated as a "high" percent indicates a slow penetration of the sheet by the water.
Two types of top sheets, i.e., a "standard" and a "quick strikethrough" (QS) top sheet, were used in diapers having shortened side flaps and improved containment as measured by leg leakage of the diapers was achieved with both of the top sheets as compared to similar diapers with the same top sheet but not having the shortened side flaps. The standard top sheet was a print bonded rayon non-woven fabric having a basis weight of 18 to 19 grams per square yard. The rayon used was 11/2 denier, 11/8 inch staple in the form of a carded web. The bonding agent used was Rohm and Haas Rhoplex, HA-8. The standard top sheet is available from Kendall Co., Fiber Products Division, Walpole, Mass. 02081 under their designation, Webline, F6211. The runoff of water for the standard top sheet was 30 percent when the sheet was inclined 5° and 75 percent when the sheet was inclined 20°. The QS top sheet was the same as the standard except that a different bonding agent, which is not known to applicants at this time, was used. The QS top sheet is also available from Kendall Co. and is identified by Kendall Co. as SW 269-3. The runoff of water for the QS top sheet was zero percent when the sheet was inclined 5° and 3.0 percent when the sheet was inclined 20°.
FIGS. 4 and 5 show a diaper of another shape incorporating the shortened side flaps of this invention. The absorbent pad 49 of this diaper has essentially an hourglass outline or lineaments wherein 34 is the anterior end of the pad, 35 is the posterior end of the pad and the side edges 48 of the pad are curved inwardly from a rectangular pattern. The absorbent pad 49 can be constructed as described previously wherein it has an absorbent body and a top sheet. The back sheet 50 underlies the absorbent pad and has a substantially rectangualr periphery about as wide as the anterior and posterior ends of the absorbent pad 49. The diaper of FIG. 5 was formed from the pad of FIG. 4 by folding the absorbent pad 49 and the portion of the back sheet 50 underlying the absorbent pad 49 in accordance with the teachings of the commonly owned copending U.S. application Ser. No. 119,420, filed Feb. 26, 1971, entitled DISPOSABLE DIAPER, now U.S. Pat. No. 3,710,797, incorporated herein by reference, and by folding the side flaps 25, i.e., the portions of the back sheet 50 not covered by the absorbent pad 49 due to the hourlgass shape of the pad 49, over and onto the top surface of the absorbent pad 49 with side flap outfolds 69 and 70 extending from end point 65 to external point 54 and from end point 66 to external point 55, respectively. The side fold glue spots 36 are an adhesive means to maintain the infolds 26 while the diaper is worn, and the lines of attachment 29 are on the top surface of absorbent pad 29.
The fold pattern taught by the above mentioned application Ser. No. 119,420 is as follows: A composite central fold 71 is provided extending from the end point 65 to the end point 66. The central fold 71 separates the entire diaper into approximately equal portions, i.e., an anterior and a posterior portion. The central fold 71 includes a central infold 56 extending between the inner point 57 and the inner point 58. Intermediate outfolds 59 and 60 are provided extending outwardly from the inner points 57 and 58, respectively, to the intermediate points 61 and 62, respectively. The outer infolds 63 and 64 extend to the end points 65 and 66, respectively, from the intermediate points 61 and 62, respectively.
Posterior joinder points 51 and 51' and anterior joinder points 52 and 52' are provided as convergence points for additional infolds and outfolds along the side edges of the diaper preferably so that each joinder point is further from the central fold 71 than it is from its nearest anterior or posterior end 34 or 35. Each of the joinder points 51, 51', 52 and 52' preferably lies at about the same distance from the central fold 71. Extending from the joinder points are the infolds 26. The pair of infolds 26 on the left side of the diaper merge at the inner point 58 and the pair of infolds in the right side of the diaper merge at the inner point 57. Similarly, the pair of outfolds 27 on the left side extend from the joinder points 51 and 52 to the intermediate point 61 and the pair of outfolds 27 on the right side extend from the joinder points 52 and 52' to the intermediate point 62.
With the above combination of infolds and outfolds, the diaper of FIG. 4 is readily folded on itself during which manipulation it passes through the configuration illustrated in FIG. 5. This is accomplished by merely bringing the ends of the pad 34 and 35 together so that the central infold 56 in effect functions as a hinge point. In the course of the folding sequence, the inner triangular areas 67 fold inwardly (see FIG. 2) against the areas of the top surface of the absorbent pad 49 which adjoin the infolds 26. Similarly, the outer triangular areas 68 formed on either side of the outer infolds 63 and 64 fold together in pairs as a result of the outfolds 27. Thus, when the diaper is folded in half a full double gusset fold is formed at each side of the diaper by the triangular areas 67 and 68.
The distal edge 30 of the side flap 25 in the diaper of FIG. 5 in its end-supported flattened condition is shorter than the projection 38 of the distal edge 30 on the top surface of the absorbent pad 49. The shortening of the side flap 25 spaces the distal edge 30 from the top surface of the absorbent pad 49 as is shown in FIG. 5. The fact that the distal edge 30 is shorter than its projection on the top surface of the absorbent pad 49 is readily apparent from FIG. 4 by noticing that the distal edge 30 is the shortest distance between the posterior joinder 51 and the anterior joinder 52 of the fold lines 26 and 27, whereas the projection 38 of the distal edge 30 when the absorbent pad is in the end-supported flattened condition lies within the area between outfold 27 and the side edge 48 of the absorbent pad 49.
FIG. 6 being a cross section through FIG. 5 illustrates the spacing of the distal end 30 from the top surface of the absorbent pad 49 whereby the side flap creates a dam to prevent fluid bypass. FIG. 6 also shows more detail of the diaper structure wherein the side flap 25 is a marginal portion of the back sheet 50. The absorbent pad 49 is shown having an absorbent body 21 and a top sheet 22. The top sheet 22 is secured to the bottom side of the absorbent body 21 by a glue line 39 extending along and adjacent to the side edge of the absorbent body 21. The side flap 25/back sheet 50 is attached to the top surface of the absorbent pad by a line of attachment 29 which is an adhesive means extending along and adjacent to the side edge 48 of the absorbent pad.
FIG. 7 illustrates an alternate construction of a side flap for a diaper as shown in FIG. 5. The back sheet 50 is trimmed to essentially coincide with the side edge 48 of the absorbent pad and is attached to the bottom of the absorbent pad by adhesive means, such as hot melt glue 72. The side flap 25 is separately formed and secured to the back sheet 50 by the line of attachment 29.
The diapers illustrated in FIGS. 8 and 9 are another embodiment of a diaper having shortened side flaps. The unfolded diaper shown in FIG. 8 is formed like the unfolded diaper of FIG 1 but folded in accordance with the teachings of the previously mentioned U.S. application, Ser. No. 119,420. The line of attachment 29 is between the top surface of the absorbent pad 53 and the side flaps 25, and the line of attachment 29 is along and adjacent to the side edge of the absorbent pad 53. The diaper of FIGS. 8 and 9 also can have the side fold glue spot 36 to maintain the infolds 26 during a wearing of the diaper. Fold line 27 is again an outfold and center fold 46 is an infold.
In the embodiment of FIGS. 8 and 9, the side flap 25 is shortened as described in conjunction with FIGS. 1 and 2, i.e., making the distal edge 30 shorter than the length of the side flap along the line of attachment 29. As mentioned above, a triangular pleat in the side flap 25, heating the distal edge 30 of a side flap material having therein internal stresses, or attaching points on the distal edge 30 endwardly from their normal location on the absorbent pad will provide a side flap wherein the distal edge 30 is shorter than its projection on the top surface of the absorbent pad when the pad is in an end-supported condition.
Attaching the distal edge 30 of the side flaps 25 at the top surface of the absorbent pad 53 adjacent the intersections 40 of the distal edge 30 and the outfolds 27 maintains the side flaps over the top surface of the pad 49 to make an easier-to-handle diaper. Although it is preferred that the distal edge 30 of the side flap 25 be attached to the top surface of the absorbent pad 53 at the intersection 40, it is not absolutely necessary to do so to acquire an effective shortened side flap.
The shortness of the distal edge 30 insures that the first line of restraint in an open diaper will be in the side flap 25 and essentially along the distal edge 30. Thus when a diaper is in the "worn" configuration as shown in FIG. 10, the distal edge 30 of the side flap 25 is spaced from the absorbent pad to contact an infant's thigh 41 and prevent bypass between the thigh 41 and the outer portion 45 of the absorbent pad 49 of the diaper. This gives both better containment and more comfort to the infant because the portion close to his thigh is a flexible member which will follow the infant's movement more easily than a thick walled absorbent pad. Also, the flexible side flaps 25 will not bind or restrict movement of an infant's thigh. The diaper in FIG. 10 is numbered to correspond to that of FIG. 9.
Thus it is apparent that there has been provided, in accordance with the invention, an improvement for disposable diapers that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and broad scope of the appended claims.