CA1063301A

CA1063301A - Diaper insert

Info

Publication number: CA1063301A
Application number: CA227,362A
Authority: CA
Inventors: John J. Duane; Charles B. Lindner
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1974-06-18
Filing date: 1975-05-20
Publication date: 1979-10-02
Also published as: FR2275162B2; BE830343R; NO752158L; DE2525988A1; JPS5114435A; SE7506952L; ATA463375A; ZA753886B; NL7507199A; FR2275162A2; DK270575A; CH594376A5; AU8215375A; IT1040647B; US3886941A; GB1476285A; JPS5327655B2; AT352043B

Abstract

DIAPER INSERT

ABSTRACT OF THE DISCLOSURE

A disposable diaper insert for use with a dis-posable or non-disposable diaper for added absorbency comprised of, in combination, at least one absorbent pad disposed between a liquid impermeable topsheet and a liquid impermeable bottom sheet, each of said sheets being formed from a hydrophobic material such as a thermoplastic film and each of said films being characterized by a plurality of valvular apertures or valvular openings therein and a system of dimples disposed across the surface thereof.

S P E C I F I C A T I O N

1.

Description

1~633Vl DIAPER INSERT

The present invention relates to diapers and more par~icularly to disposable inserts for dis- ~ -posable or non-disposable diapers which are adapted to provide improved absorbency, and which can be used once and thrown away. In a more speciic aspect, the disposable diaper inser~s of the present invention are utilized in conjunction with disposable or non-disposable diapers whereby only the disposable diaper insert is discarded after soilage, thereby permitting future use of the diaper.
Disposable diapers have been known in the art or a number o years, and are now gaining wide-spread acceptance by consumers, both in private homes and in hospitals and institutions. Their present success is achieved in part by the elimination of the necessity of storing, washing and folding the disposable diaper as i8 the case with the conventional cotton woven diapers.
To compete with~the conventional product, the cost of the disposable diaper must be relatively low and it should be similar to a cloth diaper with regard to -absorbency, softness, bulk and conformability. ii, In both types of diapers, premature removal rom the infant adds considerably to the consumer's problem . , , ! , , as re1ected either by the increased labor effort required to clean co~ventional diapers or by the expense of replac~
ing the disposable diaper. This premature removal can be `
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2. ~ ;
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:10633~
_ motivaited by a variety of factors but is mainly attribut-able to the effect of partial saturation of the diaper.
Thus when an infant partially wets a diaper, the mother or the consumer is prone to immiediately replace the :
diaper due to her associating wetness with "diaper rash", odor, discomfort and other such characteristics.
Attempts to ameliorate the problems by utilizing diaper aids, e.g., dlsposable absorbent diaper inserts, or `
"booster pads", have not been entirely satisfactory for a variety of reasons. Merely as illustrative, the conven-.
tional diaper aids suffer from one or more of the following disadvantage~:
(a) They do not possess sufficient absorptive capacity;
(b) They are uncomfortable to the user; and (c) They suffer from poor liquid retention properties after absorption.
It will of course be understood that the terms "diaper aids","booster pads" and "diaper inserts" are susceptible to various~interpretations and meanings. As used herein, however, it is intended that these terms designate absorbent material or products to be used in conjunction with conventional diapers (as contrasted to their being part of the structure of the diaper) in order to provide additional advantages such as improved absorbency and reduce~d leakage rom the diaper.
It is therefore an object of the present . .
invention-to provide an insert or diapers which can be utilized in conjunction with a conventional diaper so as ;~
to provide added absorbency and which can be easily removed from the diaper, after soilage, and discarded permitting future use of the diaper.
Another object of the presen~ invention is to provide a diaper insert for disposable diapers which -~
enables the ~iiaper to be utilized for relatively longer ,. .

3.

:~L01~33(~1 periods of ~ime thereby providing increased economical operation.
Another object is to provide a diaper insert for diapers which have a high degree of liquid retention.
A stlll urther object is to provide a diaper insert for disposable diapers having a high degree of initial absorption or wicking properties.
These and other objects will become apparent from the description of the invention taken in con-junction with the accompanying drawings in which:
Fig. 1 is a perspective view of the diaper insert made in accordance with the present invention with some portions opened up to reveal other portions and certain details of construction.
Fig. 2 is a section taken along the line 2-2 of Fig. 1.
Fig. 3 is an enlarged fragmentary cross-section of Fig. 2 showing a section of the diaper insert during unsat-uration.
Fig. 4 is a view similar to Fig 3 except that the diaper insert is saturated with liquid.
Fig. 5 is a plan view, partially cut away of~a diaper insert according to a further, but less pre-ferred embodiment of the present invention.
~ Fig 6 is a plan view of a diaper insert wherein ``;
the absorbent material has a contoured coniguration.
Fig 7 is a plan view of a conventional diaper showing the diaper insert in position on the diaper.
In its~broad aspect, the disposable diaper insert of th~ present lnvention is comprised of, in combination, at least one absorbent pad disposed between a liquid impermeable topsheet and a liquid impermeable bottom sheet, each of said sheets being formed from a hydrophobic material such as a thermoplastic film and each of said films being characterized ;~
by a plurality of valw lar apertures or openings therein and a system of dimples disposed across the~surface thereof. ~;
Referring in detail to Fig. 1 there is shown a dlsposable diaper insert, generally designated 10, 1C~633~
. . `
comprising a rectangular absorbent pad 12 substantially centrally located and sandwiched between a thin, flexible bottom sheet 14 of liquid impermeable material, and a thin flexible topsheet 16 also of a normally liquid impermeable material. Bottom sheet 14 and topsheet 16 have a plurality of slits 18 and a system of dimples 22 therein which slits and dimples will be described in greater detail hereinafter.
Bottom sheet 14 and topsheet 16 are of approximately equal size and are of a length and width slightly greater than the corresponding dimensions of absorbent pad 12. The edges of bottom sheet 14 and topsheet 16 are sealed to each other around the entire periphery of the insert 10 and just outside the outermost edges of absorbent pad 12. The sealing can be accomplished by any convenient means, such as the use of an adhesive, but heat sealing is preferred and is indicated by heat seal 20 around the periphery of the insert.
The absorbent pad 12 can be a plurality of layers . . .
of absorbent tissue paper or wadding stacked to the desired thickness. The wadding layers need not be adhered to each other but, since it~has been common practice to adhesively, mechanically, or otherwise secure the layers to each other to maintain the relative position of the layers and the shape of the absorbent pad, such can also be done in` the insert of the present invention. The wadding can be stacked to form a pad~o~ any desired thickness and hence absorbency can be controlled for any particular use.
Absorbent materials other than tissue and wadding will of course be useful in the insert con-struction of the present invention. For example, ; :`.
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106330~

absorbent non-woven pads can be fabricated to any desired thickness and substituted for the absorbent pads described above. One such absorbent pad which has been used extensively in disposable diapers is a wood pulp product commonly known as wood fluff and is prepared in the same manner as a non-woven fabric. Thus such type absorbent pad is also useful as the absorbent pads of the lnserts of the present invention.
The only criteria for utility in the present invention are that the material be absorbent, be capable of being fabricated in the form of a pad, be compatible with the waste products with which it will come in contact and be non-irritating to the skin Various natural and synthetic polymeric materials are themselves absorbent or can be made absorbent and will therefore be useful as, or in combination with, the absorbent pad of the present invention. One group of polymers which are paxticularly preferred are insoluble hydrophi~lic homopolymers and copolymers which form a gel upon absorption of water. These materials ofer the obvious advantage of holding tenaciously to liquid and preventing the release of liquid from the absorbent article and leaking or wetting skin or clothing with which t~ie absorbent article is in contact. `
. In practice, the materials which have been found particularly useful are insoluble hydrophilic polymers prepared from the following starting materials:
poly(alkylene oxides), e.g. poly(ethylene oxide), polyvinyl alcohol, polyvinylmethyl ether, copolymers of maleic anhydride and ethylene, copolymers of maLeic anhydride and vinylmethyl ether, polyelectrolytes, etc. ;
~.', . . .
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6.
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~ 1 0 6 33 0 Insoluble hydrophilic polymers, sometimesreferred to as "hydrogels", are especially useful in the ,present invention because they possess the ability to consume very large amounts of water in the order of 25 to 100 times their dry weight.
The term "insoluble" or "insolubilization" as employed in relation to these polymers is intended to define the formation;of a gel which does not flow and does not expel water under the pressures encountered in the use of products described above.
The insolubilization can be effected by a wide variety of methods and includes, but is not limited to, -ionizing and nonionizing radiation and chemical cross-linking th,rough covalent and ionic bonding. ,, A particularly preferred hydxogel for use in the articles of this invention is comprised of at least one , , hydrophilic polymer of the formula , , ~ ~ R3 ~ R4 - Rl - 0 ~ C - C - 0 ) R~
~ Rs R6 ~ n .
which has been cross-Iinked and wherein Rl and R2 are selected from the group consisting of hydrogen, alkyl radicals and alkyl substituted aryl radicals, and wherein R3-R6 are selected from ,the group consisting of hydrogen, methyl, phenyl and vinyl radicals, and n is greater than one. i The hydrogels are polymeric compounds contain- ~ ;
ing at least o~e of the structural units shown below:

~ ~l0633~

.
Rl R2 _--C ~ C , O_ _ H
.

-- C --- - C. O ~ _ _ R3 R4 ~
' ' '' , Rl R2 . ,.' .. "~ .
---- C . f _ o ~

/ , :
. / ,:"' ' / H .
--- C ---- C _ ~ ~','', ' '.
R3 R4 .;
_ ~ '".,:
, wherein Rl-R4 are selected from the group consisting of hydrogen, methyl, phenyl and vinyl radicals.
These hydrophilic polymers may include carbon-to-carbon cross-linking between straight chain carbon : ;
atoms and the carbon atoms o~ branch c~ain methyl groups and in addition a very minor ~nd insignificant number of bonds may include two oxygen atoms linking the carbon atoms.
The polymeric gel compounds may contain cross-linking bonds present as inter-molecular bonds (e.g.
between two different molecules) and intramolecular .:
bonds (e.g. be~ween carbon atoms of the same molecule), and combinations of intra and intermolecular cross-linking , bonds.
~ '. "

8.
, 3L0633V:l The hydrogeIs can be used in the diaper con-structions of the present invention either Ln the form of thin transparent sheets disposed between or in place of wadding layers of the absorbent pad or can be embedded in the fibers of the absorbent pad as a powder or in shredded form.~ The manner in which the materials are incorporated into the pad is not critical since it is merely necessary to have the polymers c~me in contact with the liquid which penetrates the topsheet of the absorbent article.
The materials used in the fabrication of the topsheet and bottom sheet of the diaper insert of the present invention are also not limited to any particular chemic~l composition since it ls their physical properties rather than their chemical properties which are important :
in the articles of the invention. These materials should, of course, be thin, flexible, self-supporting, and sub-stantially water impermeable sheets or films. Preferably they are thermoplastic films which are capable of being heat sealed to each other.
The bottom sheet and topsheet can be an olefinic or vinyl film. Merely as illustrative, polyethylene of a thickness of rom about 0,4 to about 1.5 mils can be employed. This type of film has previously been used extensively in disposable diapers and commonly has had an embossed design in its surface to simulate the appearance and hand of cloth. These manufacturing techniques will also find use in the diaper inserts of the present invention.
Any film which is useful as a bottom sheet will also be useful as a topsheet for the disposabIe absorben~ insert of the invention. It is preferable, however, to use a film for ~he bottom sheet and topshee~

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. . ~ ... ~. ..... . ..

3 3 ~1 which resembles cloth more closely in feel and appearance.
One ~ilm which has been found particularly useful is ethylene-ethyl acrylate film. This copolymer is cloth-like, softer and stronger after slitting than poly-ethylene film. The ~ilm should have a thickness of from about 0.4 to about 2.0 mils with about 1.0 to 1.5 mils being preferred.
As described above, the bottom sheet and top-. . .
sheet are made from a substantially liquid impermeable mate-rial and must be provided with valvular openings to be effective as the diaper insert of the present invention.
The term "valvular" as used throughout the ~
specification and in the claims is intended to refer to -;
apertures in the bottom sheet and topsheet which are capable of opening to permit passage of liquid under certain circumstances and reclosing to retard passage of liquid under certain other circumstances. When open, the val w lar openings should have the ability to pass at least 20 milliliters of liquid within 10 seconds when an area of about 20 square inches is wet~ted. These openings may be of two basic~types, substantially straight slits and punctures.
The slits usefuI in the present in~ention must be su~stantially straight since, if they are curved, V-shaped or of~any other configuration, they will ~orm flaps in the surface of the film which are too easily opened and tend to remain open. Such slits, while permLtting sufficient passage of liquid in the direction of the absorbent pad, do not act to substantially reduce backflow of liquid, which is the primary object of the present lnvention. This disadvantage is also present if holes are formed in the film by removing pieces of film :
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~ Cl 63301 material as opposed to puncturing the film without removal of film material. The film is ~hereby left open to the uncontrolled passage of liqùid in both directions.
Fig. 1 shows a preferred arrangement of slits The slits 18 are arranged in longîtudinal rows in a manner such that each row constitutes a longitudinal array o~ substantially parallel straight slits each angularly disposed with respect to the longitudinal axis of the row. Adjacent rows are similarly disposed except that the slits are arranged in a manner such that the end points of each slit lie in a line su~stantially between the end points of corresponding slits in the ad~acent alternate rows. The slits should each ~e rom about 0.030 to about 0.25 inch in length. Preferably there are from about 30 to about 150 slits per square inch, each of such slits being from about 0~07 to about 0.2 inch in length. The most preferred film contains about 81 slits per square inch, each about 0.1 inch in length. ~
~ The slits can be formed according to the methods described in U.S. Patent 3,762,255 issued October 2, 1973 and entitled "Me~hod and Apparatus for Piercing Thln Sheet Material". Briefly, there is disclosed ~herein a . method and apparatus for piercing thin sheet material, such as plastic film, wherein the sheet material is passed between a piercing member having a plurality o independently resilient protrusions extending therefrom and a backing member having a retiform exterior surface. The piercing . . .
member or backu~ member is moved relative to the other member, thereby causing the resilient protrusions to follow the retiform surface and selecti~ely pierce the film.

11.

... . , . . . ~ . " .

J ~63301 The piercing member can be a metal com~, a ~ire brush or a metal strip having a plurality of substantially parallel slits extending from one edge thereof in the direction of the opposite edge defining the resilient protrusions.
The backing member can be a wire screen, a perforated metal sheet, an engraved metal roll or an endless belt -~
which is driven longitudinally with respect to the .
- piercing member.
The depressed areas 22 ~dimples) are d;stributed across the surface of the topsheet and bottom sheet in . . .
the manner shown in Figs. 1-4. Thus, it will be seen ..
tha~ the bottom sheet 14 and topsheet 16 contain a plurality of dimples arranged in staggered parallel rows along the surface of the bottom sheet and topsheet (Fig. 1) and which extend beyond the plane o the bottom sheet and topsheet (Figs. 2 and 3). The coniguration of these dimples can be circular, eliptical, rectangular, diamond ;
shaped, and the like,~the important criteria being that they be formed in a manner such that there is substantially no breaking or cutting of the topsheet during or after fabrication.
The full advantages of the present invention are not achieved if, during fabrication of the dimples, the bottom sheet or topsheet is broken, cut, or melted to an extent which would hinder the controlled passage of liquid to the absorbent pad ~which as explained pre~iously, is the function of the valvular openings).
It will be ev~.dent that if cutting or breaking of either , sheet occurs during fabrication of the dimples, that the liquid will pass through these cuts or breaks when the absorbent pad is unsaturated and once the absorbent pad 12.

:1063301 is saturated or e~en partially sat~rated, that these entry points will also serve'as poin~s or sites through which the liquid exudes back through the topsheet in contact with, for example, a baby's skin.
For these reasons and furthermore in view of the '' ease and simplicity of fabrication, I have found that the preferred form of the dimple is circular as shown in Figs. 1-4.
The dimples can be formed in the bottom sheet and topsheet in a variety of ways. The easiest and therefore the most preferred method involves the use of a roller equipped with heating means and hav~ing a number of spikes or probes extending therefr~m across the width of the roller and around its circumference. The spikes, ' ' pins, or probes, which have smooth, rounded end points, ~;
can be spaced as desired on the roller in order to provide i`
the desired number of dimples to the diaper insert~ The dimples are provided on the diaper insert preferably after the valvular openings, and this operation can be effected by passing the diaper insert containing the ~valvular openings in contact with t~e heated roller.
In this technique, the diaper insert is supported on a resilient back-up member, such as an endless conveyor belt, or a resilient back-up roller. The depth o~ the d-lmple ~an 'be controlled by limiting the depth to which the'probes depress the film. If desired, portions of the topshee~ and bottom sheet may be retained in their untreated (~ithout the dimples) condition. This can be accomplished, for example, along a strip about one inch wide near the periphery of the bottom sheet and topsheet.
Since each ~heet or film is the'rmoplastic, the amount 13.

, . - . . - i . .
,"
:; , . . ..

of hea~ and pressure applied to the areas to be treated should be strictly controlled in order to avoid substantially puncturing the material. As a general rule, the amount of heat required should be enough to so~ten the film, and the amount of pressure should be sufficient to plastically distort the film to the general contour o~ the probe. It -will, of course, be understood that the correct heat and pressure conditions will depend (among other variables) - upon the residence time of the treated absorbent pad, i.e., the length of time the sheet is in contact with the roller; the thickness of the absorbent pad, etc. The correct conditions, however, can be easily ascertained by one skilled in the art and hence no further detailed description of the conditions appears necessary.
Referring specifically to Figs. 3 and 4, it will be seen that the dimples 22 extend beyond the plane of the bottom sheet 14 and top sheet 16 a short distance, and that the absorbent material 12a,immediately below (or above) each dimple, i8 in a compressed state. At the site where a dimple i8 formied ouer a portion of the slit 18l it ~ ;
will be seen that the slit is opened to a much greater degree than corresponding slits situated remote ~rom the dimples 22. ~i However, because of the placement of the dimples J the slits disposed between corresponding dimples are opened to a greater extent than would be the case if no dimples were . .
present. This is attributed to the fact that the pressure exerted on the surface of the topsheet and bottom sheet by the dimples causes the slits to open slightly under the influence of the stretching of the sheet, PortLons of the compressed absorbent pad are associated with these opened slits, and because of this association, wicking is ., ' achieved at a degree never heretofore achieved. As a matter of fact, in most cases, wicking is instantaneous.
As the liquid ;5 transferred to the absorbent pad 12, the a~sor~ent pad absor~s the liquid throughout its entire area until either partiaL or full saturation. As will be seen in Fig. 4, (which depicts a saturated a~sor~ent pad), the compressed material 12a has expanded and urges the dimples 22 outward, closer to the plane of the bottom sheet and topsheet respectively. This action serves to close the previously opened slits, thereby trapping ~ ;
the bulk of the liquid in the absorbent pad. ;
Thus, ad~antageously, according to the present -invention, maximum wicking and a~sorption is achieved during t~e critical period when flooding, (such as by ~-urination and the like~ is experienced, whereas transfer of the liquid from the absorbent pad back through the same slit opening is substantially reduced by virtue of the com~ination of the val w lar action of the slit and the ^
dimple.
The dimpLes can be arranged on the absorbent ;
articLe in a vari~ty of patterns. Thus, the overall ~ ;
design effect can be diamond shaped, curvilinear, herring~one and the Like. The preferred design con-figuration is a system of substantially straight staggered, parallel rows along the surface of the topsheet. The number ;~
of dimpLes per square inch of absorbent pad area can be varied over a relatively wide range.
The advantages and wicking characteristics of the dimpLe-alit combination are fully described in U.S.
Patent 3,814,101. The range of slit size, dimple size and freque~cy of each are fully disclosed thereunder. The 1$

,~7 1063301 ~

principa~ difference h~tw~een the a~s.~rb.ent article dis~
closed t~ereunder and tXe ins:tant di`aper ihserts is that in ;
the diaper ins.ert, ~.oth.s;ides:, i.e. top and bottom s.~eets, ; .
are s;litted and dïmpled therefiy permïtting rapid a~sorption ~:
on b.ot~ s;ides of the diaper insert. Thus, as disclosed ..
and demonstrated in s.aid patent, improvements have been ~ :
noted utilizing as little as one dimple (having a -.
diameter of .05 inch) per s.quare inch of absorbent pad. .`.
Good results are obtained when as many as 100 dimples :
1~ (.05 inch.diameter) per square inch of absorbent pad area .
are utilized. It will of course be understood that the number of dimples per square inch of absorbent pad area :.:
depends on the dimpl~ s;ize. As a general rule, the total area occupied by dimples should not exceed more than 20 per cen.t af the area of the abs.orbent material. Excellent reaults: are achieved when.the total dimple area is from ! '`~

4 to ~2 per cent o the area of the absorbent material.
Preferab.ly there are from about 3 to about 25 dimples ~:.LQ inch diameter~per square inch of absorbent material .
area, and most pre~erably from about 6 to about 13 per square inch of absorbent pad area.
As a general rule, dimple size can be in the range of about 0.025 to about 0.250 inch diameter. From . .
the.s:tandpoint of functional and aesthetic qua~ities, it is ..
pre.ferred that the dimple s.ize range from a~out 0.075 ~ :
to a~.~ut Q.15Q inch.d~.ameter.
In.s:tiLl another, ~.ut:les.s pre~erred embodiment, the dimplesi are asso~cï~ated ~ith t~e diaper insert depicted ~ .
i~ Fig. 5 w~erein the slits 18 are s.hown as ~eing in ''r ~'' 3Q straight parallel relation. ~: ........... :.
'.: :' -, -- 16. -.~
~ ',.~'' ''~ ' 1~)6330~
The fabrication o the diaper insert may be accomplished by a variety of techniques. In a preferred technique, a thin film of thermoplastic material such as an ethylene ethyl acrylate film of the desired thickness is slit according to the procedure described previously.
After the slitting operationJ the assembly of the diaper insert, more or less, follows conventional methods of fabrication. The topsheet and bottom sheet are cut to approximately the same dimensions which are equal to the desired siæe o~ the final diaper insert. The size can be varied according to the desired use, for example, in rectangular form the diaper insert can have a width of 4-6 inches and a length of 10-18 inches The topsheet and bottom sheet are juxtaposed one on the other with the absorben~ pad sandwiched there-between in approximately the center of the sheets. The absorbent pad should be of a length and width slightly smaller than the topsheet and bottom sheet to permit sealing of the topsheet to the backing sheet around their , .
periphery. An overhang of about 1/2 inch on each side should be sufficient. Sealing can conveniently be acaomplished by heat sealing the edges. The heat sealing might also be used to simultaneously accompiish a cutting of the edges to trim excess sheet material from the diaper and yield a diaper structure which is neat in its appearance.
If desired, the absorbent pad may be of hour glass configuration (contoured). In this case, and for ease of fabrication, only the absorbent pad is of hourglass coniguration. The bbttom sheet and topsheet can be rectangular so as to facilitate the heat sealing of 17.

.

the edges.
Thus, referring to Fig. 6, where like'parts are designated by like reference numerals, it will be seen that the absorbent pad 12 is of hourglass con-figuration, and is sandwiched between botto~ sheet 14 and topsheet 16. It will be noted that the bottom sheet and topsheet are substantially rectangular whereas the absorbent pad 12 is of hourglass configura-, tion. ThiR design is merely or ease of fabrication ~, since it will be obvious that the topsheet and bottom sheet can also be of substantially hourglass configuration, corresponding to'the shape of absorbent pad 12.
The diaper insert of the'instant invention can be utilized in conjunction with con~entional dlapers of the disposable or non-disposable type. The insert is normally positioned in the center of the diaper as shown in Fig, t, the diaper insert 10 is positioned on ~iaper 24 on the side which would normally be in contact wi~h a baby 7 S skin~ The diaper 24 shown in Fig. 7 is of the disposable type having a "wing" fold design. This type o~ fold permits the use of the diaper insert without any securing means since the insert can be held in position by the edges ''' formed by the wing old. In other type designs, ,, it may be necessary to include attachment means such '' as tape fasteners and the like in order to prevent ', migration of the insert during operation. These type ' ',of securement means are well known in the'art and hence no detailed description appears necessary.
When in position on the'diaper, the structure ~ '~
of the insert permits the'rapid absorption of liquid ',~
' ~, 18. ;
~.

;~ - \
`` ~06330~ :

through the topsheet. However, when excessive flooding occurs, some of the liquid may flow around the insert between the bottom sheet of the insert and ~he absorb-ing surface of the conventional diaper. Since the bottom sheet of the insert i8 also capable of absorb-ing liqu~d as explained previously, some of the liquid will be absorbed into the insèrt via the bottom sh~et thereby minimizing the flow of excess liquid in~o the diaper.
Surprisingly, it has been found that the combination of the diaper insert and the diaper results in the diaper insert and diaper totally absorbing a disproportionately higher urine load than if the absorbent contained in the diaper insert were added to the diaper absorbent and made an integral part of the diaper. In other words, the degree of to~al absorbing i8 greater when the diaper insert and diaper are utilized as described herein as contrasted to using the diaper without the diaper insert but 20; containing the combined amount of absorbent material of the basic diaper and diaper insert.
The slit-dimple construction çauses the liquid to be readily absorbed and retained by the insert ln the manner previously set forth. Thus when the insert becomes saturated or even partially .
satu~ated,~the consumer need only replace the insert leaving the basic~diaper rea~y for future use. This of course represent~ a savings in time and labor and is also highly desirable from a practical economical standpoint.
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: 19.

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Claims

WHAT IS CLAIMED IS:

1. A diaper insert which comprises, in combina-tion, at least one absorbent pad disposed between a liquid impermeable hydrophobic topsheet and a liquid impermeable hydrophobic bottom sheet, each of said sheets having a plurality of valvular openings therein, said valvular openings being substantially parallel straight slits which are substantially closable to retard back flow of liquid absorbed by said absorbent pad through said valvular openings, and a system of dimples disposed on each of said topsheet and bottom sheet, said dimples having a frequency of at least 1 per square inch of absorbent pad area.

2. A diaper insert according to claim 1 wherein said substantially parallel straight slits are disposed in longitudinal rows, each slit being angularly disposed with respect to the longitudinal axis of said row and being arranged in a manner such that the end points of each slit lie in a line substantially between the end points of corresponding slits in adjacent rows.

3. A diaper insert in accordance with claim 2 wherein each slit is from 0.07 to 0.2 inch in length and wherein said slits are present in said topsheet and said bottom sheet in an amount of about 30 to 150 per square inch of topsheet and bottom sheet.

4. A diaper insert in accordance with claim 1 wherein said dimples are disposed on said topsheet and bottom sheet in an amount of about 1 to about 100 dimples per square inch of absorbent pad area.

20.

5. A diaper insert according to claim 1 wherein said dimples are disposed on said topsheet and bottom sheet in an amount of about 3 to about 25 dimples per square inch of absorbent pad area.

6. A diaper insert according to claim 1 wherein said dimples are disposed on said topsheet and bottom sheet in an amount of about 6 to about 15 dimples per square inch of absorbent pad area.

7. A diaper insert in accordance with claim 1 wherein said dimples have a circular con-figuration with a diameter of from about 0.025 to about 0.250 inch.

8. A diaper insert according to claim 1 wherein said topsheet and bottom sheet are each 0.5 to 2.0 mil thick and of substantially the same dimensions and being at least partially adhered to each other around their periphery to form an integrated structure having the absorbent pad substantially enclosed and sandwiched between the topsheet and bottom sheet.

9. A diaper insert according to claim 8 wherein said topsheet and bottom sheet are fabricated from ethylene-ethyl acrylate.

10. A diaper insert according to claim 1 having a rectangular configuration.

11. A diaper insert according to claim 1 wherein said absorbent pad has a contoured configuration.

21.