CA1045303A - Diaper with back-to-back transition web facing - Google Patents

Abstract

Abstract of the Disclosure A disposable multi-layer diaper includes at one surface a porous fibrous facing layer to be brought into contact with the infant's skin, and includes at the other surface, a water-impervious backing sheet, with an absorb-ent batt being interposed between the facing layer and backing sheet. The facing layer is comprised of two half-thickness portions, the outer half-thickness portion to be positioned adjacent the infant's skin, being readily separable from the inner half-thickness portion, and from the remainder of the diaper, so that the outer half-thick-ness portion and any fecal matter thereon can be flushed down a standard toilet separate and apart from the remainder of the diaper including the non-degradable water-impervious backing sheet. The outer half-thickness portion is charac-terized by a given overall concentration of long and short fibers, the outer face having a concentration of long fibers in excess of the given overall concentration of long fibers in the half-thickness portion, with the long fibers decreasing in concentration closer to the inner face of the outer half-thickness portion. In the preferred embodiment, the inner half-thickness portion of the facing layer is of the same fiber concentration structure as the first half-thickness portion and through-bonded thereto with the short fiber enriched faces in juxtaposition. The concentration of short fibers at the interior of the facing layer provides a layer of weakness therein which permits the facing layer to be manually delaminated along the short fiber plane for the disposal of fecal matter.

Description

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Backqround of the Invention ` This invenkion relates to an improved disposable diaper which has an air laid fibrous facing layer ~hat has improved strength and smoothness and a portion o~ which may be easily and readily delaminated from the remainder ` of the diaper to enable fecal matter on the delaminatable - portion of the diaper to be disposed of independently from the other diaper components.
Disposable diapers have met with increased ' 10 commercial acceptance ln the recent past due both to their convenience and to their improved unctional characteris-; tics, as compared to cloth diapers. A typical disposable diaper includes a porous ~acing layer which is placed ; adjacent to the infant's skin, an absorbent pad or batt to retain body fluid that passes through the facing layer, and a moisture impervious backing sheet to confine absorbed fluids within the batt.
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-~ One o the problems encountered by the prior art .,~, ,,~... ..
has been the inability to provide a suitable light weight inexpensive facing material which is pliable, soft, comfort-able and non-irritating to infant's skin, while at the same time having adequate strength and dimensional stability, and the desired degree of porosity and water wettability. A
further problem which has more recently become a matter of concern is the disposal of disposable diapers containing ~ecal matter. With the growing concern for pollution of the environment, various regulations have been enacted by . . .:
~; ~ certain municipal governing bodies prohibiting the dis-.:; .
posal o human fecal matter through solid waste disposal systems. As a result, it has been necessary to cleanse ; ; the disposable diaper of fecal matter prior to its ,,,:,`, . ~, ~ 2 -: ", :, ;: ".: ;, /`~` '``
53~3 disposal which prescnts asthetic and sanitary problems, Certain prior art patents have disclosed means for separatlng fecal matter from the used diaper, however, they require either the separation of the biode~radable camponents of the diaper, i.e.~ facing and batt from the impervious backing sheet or remo~al of the entire facing layer ~rom the impervious backi~g sheet. Still other patent~ ha~e disclosed absorbent inserts which may be readily removed by an envelope~like liner for disposal.
Duncan et al., U~ S. Patent No. 3,180,335 dis-closes a disposable diaper in which the impervious backing sheet iæ separated ~rom the ab~orbent material by ~trlpping the absorbent material from lts marginal adhesi~e areas on the backing sheet. The Duncan et al. diaper consists of a water-impervious backlng sheet and an absorb-ent pad centrally di.sposed thereon. The pad includes multiple plies of creped eellulose wadding and is enclosed on one surface (to be positioned against the infant's skin~
and on all four ~ides by a non-woven facing layer. The facing layer is adhesively attached to the bottom ~ace o~
th~ plles o~ wadding, and the marginal side and end por-tions of the ~aCing layer, which are in ~uxtaposition with the water-impervious backing sheet, are adhered ~`
thereto.
After the diaper has been used and remo~ed from the in~ant~ the absorbent pad including the ~acing layer, :~
iS 8tripped from its adhesive attachment to the backing :
sheet. The pad is then dipped several times in a toilet until a ma~or portion of the creped wadding is re-pulped and disposed of in the water. The toilet is then flushed ' - 3 ~

`" ~ 53~t3 .while the remai.ning portions Or the pa~ ar~ hcld ~nd thcn .~ thcsc remaining portions (fac~n~, layer an~ creped pl.i~s) ar~ rlush~d a~ay. The Duncan et al. di~per achi~vcs strippability at a sacrifice to structural stability since the components are adhered to one another in only thè
~ marginal portions. This type of adherence may produce :
.. areas of non-contac~ between the pad and the backing sheet ~` 80 that urine will pool on the backing sheet when the pad separa~es therefrom. Addit~onally, since all of the absorbent material is stripped away from the backing sheet, ,`
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a large amount o~ bulk must be flushed into the sewage ByStem whlch ~ay.result in clogging.
;' Hermanson et al., UO S. Patent No. 2,649~859, .
dl~closes a diaper with a water-impervious backing sheet on which several creped cellulose ~heets are centrally .~ dlsposed, A facing sheet covers the creped plies and is .
adhered to over-turned side portions of the backing ~heet.
~'~ In thie manner, the backing sheet and facing layer form an envelope to contain the creped sheets. ~he diaper o~
' 20 the Hermanson et al. patent is open at each end, and the .' creped sheets may be sealed at their sides. When the , ., diaper is to be disposed of, the facing sheet and crepe sheets are grasped at one end of the diaper and are torn ..
: fr~m the backing sheet to be disposed of in a toilet bowl. .~;`.
, As wi~h the Duncan et al. diaper, the Hermanson ... ...
.~ et al. diaper requires the disposal of a large bulk of absorbent material ~rhich can result in clogging problems.
;
,~. Although the creped sheets in Hermanson e~ al. may be .. . .
~ealed alon~ their sides, the pooling problem, discussed i 30 above~ may also be present. ~oreover, the separation of . . .
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r , the absorbent material from the backing sheet is difficult since the area of bonding at the sides and the overlapping ~;, of the backing sheet on the facing layer may result in an ~, irregular tear line of the facing layer.
;` , The problem of providing a facing material of suit-able strength and smoothness at low cost has been met with ~,, some success. Mesek et al, U.S. Patent ~o. 3,612,055 "'''! discloses a diaper with a facing layer made of a uniform ~ !
~;~, mixture of long and short fibers, bonded together with a sj ;i ,,j , 10 resinous binder material and containing a wetting agent to provide the desired degree of wettability to the facing ~- - layer. Such a facing layer with a uniform mixture of long `~
~, and short fibers utilizes the short fibers for economy and the long fibers for strength and smoothness. It does not, however, utilize the long fibers in the facing material to maximum advantage since a substantial portion of the long fibers are in the interior portion of the facing , I material where they contribute nothing to surface smooth-;"l ness and only partially to the strength of the material.
~, 20 A recent improvement in diapers involves the :, I
utilization of a facing fabric comprising a mixture of long `i~ and short fibers with a concentration of long fibers (above ~ the overall concentration of long fibers in the total '` l facing layer) at the outer surface of the facing layer.
Such a concentration of long fibers at the outermost face of the facing layer provides added surface smoothness, provides strength where it is most needed and utilizes the ~`l long fibers in the facing material to greater effectiveness.

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~5~1D3 Summary of the Invention The present invention provides a diaper with a facing layer of nonwoven material, a portion of which may be easily delaminated, from the remainder of the diaper structure for independent removal and disposal of fecal matter. This result is accomplished by a facing layer in ~ -the form of a multi-sectioned or sandwich-like fabric having long fibers on its outer faces and an interior portion of short fibers which forms a plane or zone of weakness facilitating delamination.
No~lwoven materials are structures which, in general, consist of an assemblage or web of fibers, join~d randomly or systematically by mechanical, chemical or other means. These fibers are well known in the art having gained considerable prominence within the last 25 years or so in the consumer market, industrial-commercial market, and in the hospital field.
Fibers are usually classified according to length, with relatively long or textile length fibers being longer than about one-quarter inch and generally between one-half and two and one-half inches in lenyth. The term `'long fibers`l as used herein, refers to textile fibers having a length greater than one-quarter inch and the fibers may be of natural or synthetic origin. The term `'short fibers`', `
as used herein, refers to paper-making fibers, such as wood-pulp fibers or cotton linters having a length less than about one-quarter inch. While it is recognized that short fibers are usually substantially less costly than long ~
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,',':, ~3 ~iber~, il; is also recogni~ed in many instance3 t~lat it i~ d~sirable 1;~ stren~,then a short fiber prc>duct by inclu-d~ng a blend of long fibers therein.
Cost sa~ings in diapers utilizing non~oven fabrics can be realized by using short fibers. However, due to the low tensile strength of short ~iber *abrics, exclusive use o~ such fibers is impractical since little cohesi~eness is pres~nt in the fibrous portions o~ the dlaper in absence of a large ~mount of binder ~Ihich can ~.
adversely affect "feel" and increase overall cost. In the prior art, diapers with facing layers made from short ~:
~ibers ha~e been undesirable not only due to their low . tensile strength, but also due to the increased dusting e~ec~ caused by separation o~ individual ~ibers from the facing layer The preparation of nonwoven fabrics for use as diaper facines has heretofore be~n gener~lly limited to the use of at least a substantial percen~age of long ~.
fibers becàuse of the inabilit~ to make products from short ~ibers having the strength, light-weight drape and ~.
softness and ~eel characteristics generally associ.ated with fabrics formed of such long fibers The diaper o~ the present invention utilizes a~ a facing material a multi-sectional fabric havin~
di~feren-t concentrations of long and short fibers in dl~ferent thickness portions o~ ~he fabric~ In order to gi~e the proper ~eel and comfort characteristics as well as draping, it is desirable to have long fibers at the outer face of the facing which is to be in contact with the ~nfant. And i~ is likel~ise deslrable to have a lone fiber ~ace ad~ac~nt to the absorbent batt to maintain inte~rity , .~ . ~ , . .. .
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LSi3~3 o~ the disposable diaper. ~ facin~ layer with only ~hort fibers, or largely short ri~ers ad~acent th~ batt and adhered to the backin~ sheet in its mar~,inal port-iGns not desirable since the back~ n~ is adhered primarily ~o weak short ~ibers in these marginal portions and t'ne f`acing layer may split or separate from the backing during positioning of the diaper on the baby.
In order to have the ability to remove fecal mal~ter from a soiled diaper, it is desirable to remove a fibrous portion of the diaper containing the fecal matterO
In prior art diapers, this has been done by removing a.t least the en~ire facing layer necessitating minimal adherance between the facing layer and its ad~acent elements to the detriment of proper functioning~ According to the present invention, the ~ecal matter is removed by removing an ex~erior thickness portion o~ the ~acing layer by splitting it along a plane of ~eakness, making it possible to adhere the total marginal portion o~ the facing layer to the .. .. .
backing sheets over the entire interface bet~reen them.
Accordingly, the fac~ng layer used in the diaper in one aspect of the present invention is ~orrned ~y two half-thickness portions ~rhich are bonded to~ether -in laminar ~ashion to ~orm a composite fabric. The outer -half-thickness portion is formed of long fibels and shor~
fibers at a given overall concentration, and in order to give *his portion the proper feel and comfort characteris-tics 3 ~as well as draping~ the outer ~ace comprises a mixture o~ lon~ and short fibers ~hich is enriched with respect to lon~ ~ibers in excess o~ the overall conccntration.
And, to minimize the cost, the inner face of the outer half-thickness portion comprises a mixture Or long an~ -short f~bcr~ enriched with rcspect ~o short fibers in excess o~ the overall conc~ntration ~lithin ~he outer halr~thickness portion, the concentra~ions o~ lon~; and ~hort fibers decrease graduall~ (i.e~ there ls no sharp interface bettreen one concentration and another)0 The ~erm "tran~ition fa~ric " is used herein to re~er to a !~' ~bric of the type ~ust described.
The inner half-thickness portion is bonded to the short fiber-enriched face o~ the outer half-thickness portion and is characterized by an outer ~ace, opposite the ~ace bonded to the outer half-thickness portion, having greater ~tructural stability than the short fiber=
enriched ~ace o~ the outer half-thickness portion. In this manner, the composite ~acing in the diaper o~ this ~ embodiment is provided with out~r faces having substantlal j structural integrity, and with a some~rha~ weakened interior portion comprised essentially o~ low cost short fibers.
In a particularly pre~erred embodiment, the second half~
¦ thicknes~ portion is similar to the first half-thickness portion and bonded ~hereto in mirror-like relationship.
The process of ~orming the ~acing layer involves the use of a combination of techniques, such as shingling o~ fibers and con~rolled binder concentration which allows the facing ~abric to be ea~ily delaminated along the interior short~
fiber-enriched region.
~ The interior region, due to its low tensile strength (compared to the out~r re~ions), may be torn along the central plane, or delaminated, so that the outcr long ~iber-enriched portion on which the fecal matter has been deposited may be separated from the remainder of the diaper Since th~s ou~er layer is biode~radable, lt may ' _ 9 _ " . . ,~
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be, after being flushed down a conventional toilet, disposed of in sewage treatment facilities, thus overcoming any pollution problems and local regulations which have been promulgated to prohibit the disposal of fecal matter ~`.
through public solid waste sanitation facilities. Mo:re-over, since the facing layer is delaminated, the amount of fibrous diaper material that must be disposed of in the toilet is greatly reduced with a resultant decrease in the possibility of cloggingO
Other embodiments discussed below utilize the basic delaminatable '`sandwich1' structure facing layer to provide a diaper with easy capability for disposing of fecal matter without disposal of a large amount of fibrous material. - .
As will be discussed in greater detail below, the present invention in its preferred embodiments is dir-ected to a diaper in which the facing fabric has a transi-tion fabric half-thickness portion which is improved by the addition of a second fabric having greater structural sta-bility than the short fiber-enriched face of the transitional fabric so that the following advantages are obtained: (a) the facing layer has improved feel and strength character-istics at its outer face, (h) the tendency of the short fibers at the interior of the composite web to dust is mini- .
mized, (c) the overall production cost of the facing layer is reduced by utilization of the expensive long fibers in :
optimum distribution, (d) the inner face of the facing ; .
layer to be adhered to the backing sheet has sufficient .
structural stability so that it will not split or separate from the backing sheet; ~e) the facing fabric is easily , ,. .
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' `' 53~3 delaminated ~or the removal o~ ~ecal matter from the remainder of the diaper; and (f) thc total a~oun~ of ~ibrous bulk which mus~ be disposed of ~n a toilet bo~rl, and ultimately in a sewa~e treatment sys~em is minimiz~d.
Althou~h the composite facing layer fabric utiliæed in some embodiments o~ the present i.nvention is de~cr~bed as be~ng formed from two hal~-thickness portions, it shou~d be understood tha~ the term "hal~-thickness"
doe~ not necessarily mean ~ha~ each portion is exactly the same thickness as the other or exactly 50~ of the thickness fff the composite fabric. The half--thic~.ness portions can differ in their ~epara~e ~hicknesses, but .
when they do, the thinner por~ion shou~d comprise at least 20% of ~he total thickness of the composite ~reb.
Brief Descri~tion of the ~rawin~,s FIG. 1 is a. perspective vie~r, with certain por~ion~ broken a~Jay, of an open unfolded diaper in accordance with the present invention;
~IG, 2 is an enlarged partial cross section of the diaper o~ FIG. 1, taken generally along lin~ 2-2 in FIG. l;
FIG. 3 is a perspective vie~r on a reduced scale of the diaper in its configuration after being put on an infant, FIG. 4 is an enlarged partial cross section of the diaper ~acing layer, taken generally along li.ne 4-4 in FIGo 5; and FIG. 5 is a simplified schematic ~iew of the :
produ~ion llne on ~rhich the diaper is m.~de.

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3~ -l)etail~d Description Or the Preferred ~hodlment While this invention is susceptible of embodi-ment in many di~f`erent ~orms, there is shown in the dra~,Jings~, and will hereln be described in detail, a pre~erred embodiment o~ the invention and modi~ications thereoP~
with the understanding that the presen~ disclosure is to be considered a~ an exempli~icat~on Or the principles of the invention and is not intended to limit the in~ention to the embodiment illus~rated. ~he scope of the inven~ion will be pointed out in the appended claims.
Referring to the drawings and more particularly to FIGS. l, 2 and 3, the diaper assembly lO, when fully opened and laid out flat, comprises a lo~Jermost ~rater-impervious backing sheet 12 which is rectangular in shape, highly water-absorbent fibrous pad or batt 14, which i~
als o rect~,n.gular in shape, but smaller than the impervious-sheet and centrally disposed thereon, and an overlapping facing layer 16 of fibrous material, ~rhich is also rectan~u-lar in shape and coterminous with the impervious sheet and in contact therewith in the marginal portions o~ the diaper e~tending peripherally beyond the absorbent batt, ~.e. at the portions 16b and 12b o~ the ~acing layer 16 and ~mpervious sheet 12, re~pectlvely. The ba~t 14 has an integral, continuous, paper-like, densi~ied hi~hly compacted lowermost fibrous layer 18 ~Jhich includes spaced, parallel, thickened densified portlons 19 in the form of parallel lines that may extend completely throu~h the cross-sectional thickness of the batt. Densi~ied layer 1 is adhered to the impervious sheet 12 by bead lines 22 o~
adhesive æu~tantially throughout the inter~ace there-between Marginal portions 16b and 12b are also adhered to each other b~ bead lines 22 of adhesive.

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53~3 In the preferred embodiment of the invent~.on, moisture impervious shect 1~ i~ formed of po1.yethylene ha~in~ a thickness of approximately 0.001 inch. Th~
~heet may be smooth, or may be embossed to impro~re its drape and feel. Other suitable ~lexible moisture imper-vious sheets may be used in accordance with the invention, ~uch as, for example, polyethylene terephthalate sheets ha~ing a thickness o~ about 0.0005 inch.
Bat~ 14 is ~ormed o~ loosely compacted short cellulose ~ibers, such as wood pulp f'ibers, or cotton linter~, held together by interfiber bonds requiring no added adhesiveg as ls known in the art. Briefly, this . batt i8 a low ~ulk density coherent web of loosely com pacted cellu}ose fibers pre~erably comminuted wood pulp ~iber9 in the ~orm of so-called l~flu~ o : .
The ~aper-like densified layer 18 of batt 1~ ls formed by a slight moistening of one ~urface of the batt ~ollowed by the application o~ pressure thereto. The nature o~ the batt and of its densified layer and the method of producing the same are deæcribed in U. $.
Patent No. 3,017,304, dated January 16, 196~. The thickened densi~ied portions 19 are formed by further compression o~ batt 14 while it is still moistj as will hereina~ter appear.
The composite density of batt 14, includin~ its ~.
densi~ied layer 18, should be abo~re abou~ 0 . 07 ~m, /cc .
and preferably bet~Jeen about 0.10 and 0.15 gm./cc. The fore~oing density values are applicable to the diaper as produced. Xn storage and handlin~, the lof~ or thickness of the batt is ~ncreased to some extent, resulting in lowered densities. ~'-:~
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~L~453~3 Facing layer 16, on an overall basis, is made of a given concentration of fibers consisting of short cellulosic fibers such as wood pulp fibers or cotton linters, in amounts of about 50% to about 9~%, the balance being te~tile length fibers" such as fibers of rayon, polyester, cellulose acetate, nylon, etc. -Facing layer 16 is most preferably formed by join-ing two transition fabrics 30 and 30' (Fig. 4). Since struc-tural lntegrity is a prime consideration in the formation of the facing layer of the diaper of this invention, in any pre- ;
ferred embodiment of the present invention, a transition fabric is joined to the second fabric so that the transition fabric `
face enriched in long fibers is an outer face 15 of the facing layer. The inner face 15' of the facing layer has greater structural stability than the enriched short fiber face of the transitional fabric so that it may be adhered to the impervious sheet 12 in the marginal areasO ,, Each half-thickness portion of the facing later 16 is preferably formed by utilizing an air-laying process.
This method produces two separate transition fabrics which are joined to form the facing layer, having opposed outer major --faces 15 and 15', and central portion 17. The transition zones between the faces 15 and 15' and central portion 17 (formed by the inner faces 13 and 13') are characterized by decreasing ,~
concentrations of long fibers from the faces to the central portlon of the pro_uct. A~

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'''',.' ~45i3~3 Faces 15 and 15' preferably are comprised of a grc~trr ~mount by wei~ht of long fibers and a lesser amount by weight of ~hort cellulosic fibers (~s compared with the ~verall concentrations o~ these fibers in each transition fabric)lnterspersed and blended therewith, with central portion 17 preferably being comprised of a greater amount by weight of short cellulosic ~ibers and a lesser amount by weight of tex~ile length fibers (as compared to ~he cverall concentrations of these fibers in each transition ~abric 3 interspersed and blended therewith. It should be noted that while the central portion has been designatPd ~-a~ element 17 for identi~ication purpose~, there is no sharp inter~ace between it and faces 13 and 13' since the composition change~ are gradualO
Each transition fa~ric, on an overall basis~ is made ~rom a given overall concentration of short fibers, such a~ wood pulp fibers or cotton linters and a given overall concentration o~ long ~ibers~ such as rayon, polyester, cellulose acetate, nylon, etcO The overall concentration of long fibers may be in varying percentages - .
in a range from 2~ to 50~ and preferably from 10~ to 25 wlth ~he remainder being made up by short fibers -ror example, blends of 25% rayon fibers and 75% wood pulp fibers.
The amount o~ long fibers within the enriched face of ~he tran~ition fabric is increased by at least 30% o~ its overall concentration while ~he long flber~
are decreased by the same amount in the pulp enriched race. In the above mentioned example, having an overall concen~ra~ion o~ ~5% r~yon ~ibers and 75~ pRlp fibers, an enrichment of at least 30~ o~ long fibers means an lncrease o~ the long ~iber concentration by at least 7.5~, or to a :.

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3~ 3 ~eYel o~ at least 32.5% on one ~ace and an increase o~ the short rlber concentration by at least 7.5~, or to a level o~
at lea~t 82.5% on the other ~ace.
Facing layers suitable ~or use in thls lnventlon have ~abrio weight~ in the range of l to 5 oz/yd~2, and most pr~ferably ~Jithln the range o~ 1.75 to about ~075 oz/yd.
The present i~vention also contemplates that ~abrlcs having an eYen lower rabric weight mag be provided. Arker ~ormation, the web i8 treated wlth~a bonding a~ent, such as a se~
~0 cross-linking acrylic emulsion, and the ~aclng ~Jeb is treated ~: :
with a wetting a~ent to partially counteract the water repel- ~:
lency Or the bonding agent and brlng the faclng layer to the desired degree o~ wettability. ~ne bonding agent which has .
been employed with conslderable success is a latex o~ polyethyl- ;
acrylate copol~mer contalning small amounts o~ acrylonltrile and a cross-linking monomer sold under the trademark HYCAR ~.-2600 X 120. ~he bondin~ agent should pre~erab~y be o~ the low visco~ity type with a viscosity less than 5 cent~poisesO ~o avoid excessive water repellency, a sur~actant, pre~erably a non-ion1c sur~actant, is included in the binder suspension.
A non-lonic surfactant which has been found to be suitable i~ polyoxyethylene sorbitant monolaurate sold under the trademar~ TWEEN 20. In a typical application, the binder ~uspension is controlled to give the f~br~c a dry sol~d~
add on ln the range o~ ~rom about 4-l/2~ to 9~ based on ~he ~abric weight, of which ~rom about 0 o15~o to about 0.30 .is the amount o~ surractant. In ~acing layers havlng an ex~remely low percenta~e of textlle length ~ibers, such as in .rac~n~ layers approaching 2~ texti~e length ~ibers, the binder amount would be toward the high side ~ the ~
above mentioned ran~e. It will be understood that the : :

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` ~ ` ` . ! .. . . , ' , , abovc mentloncd surfact~nts moderate and reduce the water repellency which may bc lmpart~ to th~ short and long ~ibers of th~ ~reb by the bondinE agent ~Jhich bonds them into an inte~ral layer. After treatment ~rith a ~ret~ing agent, the facing layer is receptive to penetration by urine b~t remain. les~ wettable than the batt.
The diaper of this in~ention is normally packaged and sold in a ~olded condition as described in the Mesek et al~ U~ S. Patent No. 3g612S055. Briefly3 the ~ide margins 12b and 16b o~ the impervious sheet 12 and the facing ~abric 16, together ~ith a portion o~ batt 14, are folded inwardly in a first fold to pro~ide as the uppermost layer of the fold~ a portion of the moisture ~, impervious sheet, This sub-assembly is then folded out-wardly along each edge in a second fold to cover the ~lrst folded por~ion and to ex~o~e the edge portion of .
the facing layer as the upper layer of the double fold. In the pre~erred embodiment, each double fold at the edge o~
the diaper comprises approximately 1/3 of the resulting transverse dimension of the folded diaper, leaving appro~i-mately 1/3 o~ the width o~ the folded diaper a3 a celltral unfolded and uncovered portion. ~,.
The diaper is held in its folded condition by ~, two small central spots o~ adhesive applied between the main body o~ the diaper and the overlying sides 16b of the ~acin~ layer~ one spot on cach folded side o~ the diaper. .i~
When the diaper is to be put on the infant, the folds are opened on one side o~ each of the adhesive spots, and the ., open portlon o~ th~ di~p~r is put under the inf~nt'~
buttocks while the ~olded port,ion is raised into the ' .

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,; . . .-~lO4~i3~D3 crotch rc~,ionO The final form o~ thc diaper is sholm in perspective on a reduced scale in FIG. 3. In one form of the in~cntlon, a~ lllustrated i~ ~IG. 3~ the diaper is provided with adhesive tabs 26, each having a fixed end secured to the ~mper~ious sheet 12 and a free end wheréin ~he ~dhesive sur~ace is covered with a facing sheet. The racin~ sheets are remo~ed to ex~os~ the adhesive surfaces - when the diaper is applied to the infant, as in the config- ;
uration shown in FIG~ 3, and the free ends of the adhesive tabs are secured to opposite corners of the diaper.
S~itable fibrous structures for making the pads ~r batts 14 used in this invention are made frGm short cellulosic fibers obtained by the grinding or comminution of compacted ~ood pulp fibers or cotton linters. The batts are initially formed by air blowing the cellulosic fibers onto a s~pport at a tot~l weight of about 2 to about 10 oz./yd.2, and then subjecting the air blo~rn fibers to hea~y compression. The dense compacted paper- -like layer or skin is prepared by moistening a surface o~
the cellulosic batt with a f~ine spray of water, and then ~ub~ectin~ the moistened batt ~o pressure. The formation o~ the densified skin on the cellulosic batt is believed to be due to the ~ormation of strong hydrogen bonds between contacting moistened fibers, similar to the bonds between the fibers in p?per. By the proper sel~ction of ~-the amount of moistUre applied to the s~rface of the batt and by the proper selection of degree o~ compression imposed, the properties of the densi~ied sk~n may be ~aried ~ desired. ~he thickness~ dcnsity, strentrth and other ch~racteristlcs of the densified skin will depend ;~' .
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3~3 ~pon the unformity by wh~ch the moisture is appli.ed, the depth to which it penetrates, and the de~rce to ~rhich the fibers are compressed. For example, by finely sprayin~
about O,OQ15 cc. of ~rater per square centimeter of web ~ur~ace and then exposing the web to a priessure of about 40 lbs,/in.2, a suitable densified~ coherent paper~like ~Xin 18 is obtained on the surface o~ the web which ha~
b~en moistened. The thickene~ densified portions 19 may be obtained by subjecting ~he web to additional pressure, as by the use of an embossing roll, while the web is still moist, and the additional pressure is preferably several ~imes higher than the pressure that is appli~d to form -^
. the densified layer 18.
The short fibers used in making batt 14 of this invention are generally entirely fibers of wood pulp or -~
cotton linter~. However, other cellulosic ~ibers may be used as well as blends of cellulose fibers with other ~ibers such as silk, ~rool, nylon and cellulose acetate. `
Highly puri~ied kraft paper pulp fibers have pro~en to be most satis~actory for most applications.
The diaper of this invention may be assembled in equlpment such as that schematically shown in FIG, 5.
A roll Or short fibers 41 is provided to feed a source of ~hort cell~losic fibers to grinding mill 42 from which a -~tream o~ fibers is blo~rn onto b~lt 43 as a layer 44 weighing bel;~Jeen abou~ 2 and about 10 oz . /yd . 2, The `~ ~
air blown layer is passcd under compacting roll 1~6 ~roln `: .
which it em~r~es with enough integrity to sustain itselP
as a web without the support Or bclt 43. The ~eb th~in pa~ses throu~h a pair of calender rolls 1~7 for further compre~sion and then under nozzle 48 which deposits a fine ~:

:: - 19 - ,;

__ .
i3~
~pray Or moisture on thc upper surracç~ of the we~. The moistened web 1;hcn passes bet~leerl anoth~r s~l; Or calen~ler rolls 49 which exert heavy pressure on ~1; to form a skin 51 on its upper sur~ace l,~hich will form the d~nsificd 7 ayer 18.
The amount of moisture applied to the ~freb may vary suitably from about 0. 0005 to about 0. 03 cc ~ of water per square centimeter of web surface, depending on the thickness o~ the paper-like densified skin desired, with lesser amounts of.moisture being used for thinner webs and very thing papery skins and greater amounts for thicker webs and skins of greater ~hickness.
The amount of pressure applied by rolls 49 may vary from about 5 to about 100 or more lbs./in.2, with the commercially preferable range being ~rom about 10 to about 50 lbs,/in.2, In ~ typical embodimen~5 the ~reb is -; -~prayed trith about 0, 0015 cc . of ~rater per ~quare centi-meter of web surface and subjected to a pre~sure o~ about 40 lbs,/in.2 to ob~ain a densi~ied, coherent pape~like skin o~ uniform thickness on the surface of the ~reb which has been moistened, ~he amount of moisture is selected so that ~he web is still mois~ fol~owing formation of the skin 51, The ~reb then passes between an embossing roll 52 and a back-up roll 53 for formation of ~he thickened densified.
port,ions 19, Roll 52 has a plurality of axially spaced, circumferentially extendin~ rib-like projections 54 tha~ :
bear upon the previously formed skin 51~ and because of the residual moisture in the web and the increased pres-sure applied by pro~ections 5~, thickened dcnsified ~ :~
portions 19 are produced, ` ... .

~ 3 The pressure appl~cd by the pro~ections ~4 on the embos~in~ roll also produces recesscs or air eaps 20 (FIG~ 2) ln aligNment ~rith thickened portions 19. A~ is e~idcnt rrom FIG. 2~ the unthlc~ened portlons of th~
densified layer 18 merge with the loosely compacted batt 14 at ~ generally planar interface 213 and the thickened d~n~iried por~ions extend beyond inter~ace 21 and into ..
thç loosely compacted batt 18 to give the absorbent panel ~ thr~e dlmensional strengthening effect~
A~ter the s~in and the thickened portions are .~ormed, the absorbent ~Jeb comes in~o contact with a ~eb of ~acing material 16 and is supported thereby ~hile being cut by cutter 56 into individual batts 14.
Polyethylene ~i~n 12 is fed to the assembly from roll 58~ `~
lin~s Or adhesive being applied ~rom applicator 59. A~ .
described above, the adhesive i5 applied a~ parallel lines ~:.
or beads bet~een the impervious sheet and the densi~ied ....
layer of the batt (or the ~acing layer in the marginal portion o~ the diaper)~ Adhesive may, if des~red, be applied as a continuous layer between the polyethylene and th~ batt, but such a.pplication tends to provid~
exces~lve stiffness. The adhesive may also be applied in other patterns, such as spaced dots or other ~orms o~ ~.
~o-called l'lsland" bonds, but ~airly close overall adhes~on between the shcct and the batt ~s required and no .~.:
portlon o~ the polyetllylene should be more than about 2 inches from a point o~ adhesion. In the absence o~ such close overall adhesion, the polyethylene film may be sepa:rated ~rom the densified layer to create substantial space~ in whlch uncontrollably lar~e amounts o~ free liquid urine ca~ accumul~te.
,'.
`,' '.

. . .
, , :: . . .
. . , . ~ , ".. ~ . . ~ , .
-.: . .

After the facing material and polyethylene are brought into contact with opposite faces of the absorbent batts, -the assembly is subjected to compression by rolls 60 and 61 to shape the diaper assembly, and the individual diapers are cut off by cutter 62.
If desired, adhesive applicator 59 may be omitted and adhesion between the polyethylene layer and the fibrous layers may be achieved by heat sealing, employing a suitable sealing element in the production line.
10As illustrated in Fig. 4, the facing layer of this invention is formed by first air-laying two separate transi- ~
tion fabrics 30 and 30' which are then placed in juxtaposition 7 by a combining means 77 in the form of a roller over which the two fabrics are trained. After juxtapositioning, the webs are treated with a bonding agent, such as the above mentioned type.
The half-thickness portions are prepared initially at positions 69 and 69', which are similar in operation and correspondingly numbered. The half-thickness portions are prepared on process paths which are mirror images of one another so the fabrics being formed on each path are moving towards one another. During the description of operation, only one station will be described, but it will be understood that the description is equally applicable to the other or prime number-ed station. -The half-thickness portion 30 is prepared by .
.'' , .

.

~
.

.; . : .. . . . ~. . ~ . . .. . ... . . .

:- ~0 ~ 3~ 3 first feeding a s~ppl.y of short cellulosic fibers 70 and a supply of textile length .fibers 71 to a fibcr opcnin~
and mixing apparat~s, which takes the form Or two ,:, individual oppositely rotating lickerins 74 and 75, as descrlbed in the above-mentioned application. The'fibers ~, 70 and 71 are ~ed to the opening means 74 and 75, respec- ;
ely, at a desired rate to pro~rid~ a web 30 with a deslred o~erall fiber concentration. Lickerins 74 and 75 open the fibers from sources 70 and 71 and the fibers are ~' ~æpended in æeparate gaseo~s streams which are impelled ',, toward one another and combined to form a gaseous carrier -' stream. By ad~usting baf'fle 68 which controls the amount of interaction between the air stream from lickerins `.
7~ and 75, to a position above the center line o~ the lickerins, the fibers ~rom each separate stream will cross ':~
over one another. In this arrangement, the ~ibers ~rom ~ .
lickerin 75 ~end to be deposited onto an upstream p,ortion ~'' ' of the ~oramino~s bel~ 90 and the ~lbers ~rom llckerin 74 tend to be deposited further downstream on the pre~iously deposited ribers ~rom lickerin 75. The deposited ~ibers r ~, are condensed on ~he bel~ gO by suction box 91 which pulls , air, as by suction fans, at a high velocity, thro~gh the ,'~
belt 90 and-deposited fibers. Half-thickness portion 30 ', is,charac~erized by a ma.jor face 15 ad~acent to belt 90 ~, enr~ched in long fibers and a second major face 13 enriched in short ~ibers. And, the concentrations of long and ,~
short ~ibers decrease through the web 30 at greater dis- .
tances from their enriched facesO
The webs 30 and 30' emerging ~rom apparatus 69 ,~
and 69~ are ca.rried toward one another by conveyors 76 and 76' to a combin~n~ apparatus 77 wherein the webs are - 23 - :, .. ~ , . .... .

placed in juxtaposition so that the combined web is charac-terized by outer faces 15 and 15' enriched in long fibers.
The combined web is then carried by a conveyor 78, to a bonding station where they may be through-bonded by a binding agent and surfactant of the types described above from source 79. The left end roller of conveyor 78 is directly below and in line with combining roll 77 so that the combined web passes between the nip of roller 77 and the left end roller. The binder is deposited on one face of web from source 79 and the combined web then passes over a suction source 80 which draws the binder through the web and removes any excess binder solution~
The combined web from which facing layer 16 is to be cut is then dried by passing through drying station 81. Preferably, the drying station is in two stages;
ta) a first stage which is designed to promote a drying action throughout the depth of the combined web and is illustrated schematically by a box designated as ~2, and (~) a second stage which is designated to apply heàt to the exterior surface of the web and is illustrated by a series of alternatinyly rotating steam cans 83 and 84.
In the drying of a web by application of heat to the web surfaces, there is a tendency for the binder solution to migrate towards the heat source as the water carrier is evaporated. Reliance on surface heating as the sole means of drying may cause sufficient binder migration to adversèly affect the strength of the interior of the composite web. It is therefore preferred that a portion of the heating action be carried out in a manner .. . . . . .. . .

~ 3~ 3 - which makes heat av~ ble at thc lnterior of the ~eb, such a~ di~lectric h~atin~rg infra-red hcating, or heating by a strong current of hot air which brin~rs heat to the inter~or of the ~Jeb by convection.
The relative proportions of evaporation achieved in the ~irst and second stages will depend upon the bal-ance o~ properties desired in the final fabric. It is desired to have sufficicnt migration to the ma~or surfaces to provide the desired strength and abrasion resistance at the surfaces and to weaken the center of the fabric æufficiently to make it easy to delaminate the fabric by ~
tearing. It is not desired to weaken the center of the ~-~abric to such an extent that delamination can occur during normal use of the fabric in a diaper facing. ~;
After the drying process is completed, the ~in~ eb ~s brou~ht in~o contact with the absorbent batt material by roller 85.
For some applications, it may be desirable to through-bond ~ach half-thickness portion web separately and then bond them together. To this end, binder stations, æimilar to that described, ~rould be positioned relative to conveyors 30 and 30 ~hich would, of course, be foraminous belts . With this type of apparatus~ the ~inder station described ~rould be remo~ed and a bondlng appli-cator could be positioned between webs 30 and 30' above the combining apparatus 77 to deposit bonding at their --interface.
As discussed above, the second halr-thickness portion ~eb m~y be o~ a variety of types so lon~ as the outer ~ace (opposite the face which is bonded to ~he pulp enriohed face Or the first ha1f-thickncss portion web) i3~3 i~ O~ ereater structural integrity than the pulp-enriched ~ace of the transition wcb.
~ While the preferred embodiment utilizes t~o ~ .
~uxtaposed transition fabrics 30 and 30', it should be noted that the transition fabric~ may be different as to the nature of the long or short fibers used, the overall concen~rations, the thicknesses, or the amount o~ enrich-I ment at each face~
: ~or some uses, it may be advantageous to RSe di~erent long ~ibers ~n the hal~-thickness portions because of the different exposure of the opposite sides o~ the composite web and the different requirements at each side. For example, the o~ter face 15 (in~ended to ~ .
come into contact with the baby's skin) can be rich in long ~iber~ of rayon which pro~ides the desired ~rength in combination with a smooth feel. The opposite face which is in the interior of the diaper, where feel is not important, can be rich in long fibers of water-insoluble polyvinyl alcohol, which, despite its harsher feel, can be u~ed to providc the desired strength more effectively because of its excellent bonding propertics~ Alternativcly, ~he fabric can be rich in long polyester fibers on its outer face to pro~ide superior smoothness and rich in ,~
a le~ expensive long fiber on its opposite face.
The diaper produced by the apparatus of FIG. 5 i~ particularly useful for delamination and disposal of ~ecal mat~er since the individualized fibers of the fac.inG -:
layer are deposited on the foraminous belts 90 and 90' in a ~hingle-like manner in the lon~,itudinal direction o~
the webs,: This shingling effect, as described in Mesek, U. S. Patent No. 3,483~051, produces a ~acin~ layer

- 2~ --, : ; .. :

~ 5 3~ ~
wh~ch resists spll~tlng ln one dlrection (opposite the sh~.ngling) but which may be unl~ormly split in the shingling dlrection. ;~ -A~ter the infant has excreted recal mat~er on the diaper, the diaper is removed in ~he usual manner ~ollowing the disengagement o~ the adhe~lve tabs 26 ~rom each side o~ the impervious sheet 120 The diaper is then positloned on a ~lat sur~ace or over a tollet wi~h the -~ :
ringer~ o~ one hand grasplng an edge o~ the outer portion 15 and ~hose of the other hand grasping the impervious backing sheet 12. The racing layer is then pulled so -~hat the outer portion 15 separates or delam~nates along the central plane due to the low tenslle strength o~ the interior portion enriched in short ~ibers. A~ter the outer portion has begun to separate at an ed~e, this separa-tion is then gr~sped and the outer portion is de ~minated ~rom the inner portion o~ the ~acing layer and rema~nder .
o~ the diaper 3tructure. Slnce the outer portion 15 is characterized by a higher concentration o~ long ~ibers, it is o~ ample strength to support any ~ecal matter that has been deposited thereon and may be rolded up and :
deposlted in the toilet to be rlushed away~ The remaining portion o~ khè diaper structure lncluding the impervious sheet, batt, and remaining portion o~ the ~aclng layer i~
disposed o~ by placlng them in a su~table receptacle. In ~his manner, only a small amount o~ ~ibrous material must be rlu~hed away and clogging problems are greatly reducedO . -In maklng the diaper Or this invention by the m~thod o~ FIG. 5, belts 90 and 90~ move toward each other s ~ ;~
~nd the hal~-thickness portlons ~ormed thereon are Jolned . ..
~"'" "~
., ~ ' -27- :~

~5i3~3 ; ~

to~ether a~ their exposed surra~ces~ i.c. the sur~aces that are rich in ~hort fibers. I~ desircd, however~
bclt 90' can be arran~cd to move in the same direction ~s bclt 90 and to have fiber source 70' and 71' re~ersed in position with res~ect to the bel~ mov~ment so ~hat the short fibers are primarlly deposited upstream and are cnrlched in the ~ace in contact with the belt. In this case, the web formed in belt 90' would be taken off the belt and transposed onto the top of the web produced on belt 90 so that the short ~iber-rich sur~ace originally in contact with belt 90' comes into contact with the ~hort ~iber-rich exposed surface of the web on bel~ 90.
The facing layer of this invention can also be manufactured on a sin~le belt, rather than on a pair o~ ;
belts ~uch as belts 90 and 90'. Fiber sources 701 and 71l~ together with lickerins 74' and 75' and baffle 68' may be transposed to overlie belt 90 at a location down-s~tream o~ the comparable elements 70, 71, 74, 75 and ~8.
~In this case~ a stream rich in long fibers crossed over from lickerins 75 would be deposited first, a stream rich in ~hort fibers crossed over from lickerin 74 would be deposited second, a stream rich in shor~ fibers crossed over from lickerin 74' would be deposited thjrd, ~;~
and a stream rich ~n long fibers crossed over from lickerin 75' would be deposited fourth.
A further method of producing a sand~rich-like facing layer o~ long - short - long fibers which may also be delam~na~ed alon~ the short ~iber layer to dispose ; o$ ~ecal matter utilizes a sing~le foraminous belt similar to belt 90 on which thrce single lickerins would be .
... ,, , ,,,, ;.
.. ,,.. ,. . . ~ . . , ~ . . ... . .

~ 3 po3i~ioned. In thl~ method, t~c rirst lickerin dcposit~ -a layer o~ long ~lbers; the second llckerin then dcposlts ~hort ~ibers ~urther downskream and then a layer o~ long ~iber~ is deposited on the short ~i~er layer still ~urther : -downstre~m. This ~and~l~ch-like web is then directed to ~.
a blnder ~tation and drying s~a~ion, as discussed above;
and the web then enters the dlaper production s~ream at .
the positlon Or roller 85 ln ~IG. 5. ~ :
In the preparation o~ the foregoing sandwlch~
like web, thelicker~ns may9 if d~sired, be placed close ::
together and arranged to deposit ~ibers at closely spaced locations so that ~ome inke~mlxture will occur, providing come short ~ibers in the long ~iber-rich outer sections and a~me long ~lbers in the short ~iber-rich center sectionO
... .
There should, however7 be a de~inite distinction in the concentratlons o~ short and long ~ibers as between the central portion o~ the web and ~he opposite ~aces, ~ust as :
, .
ln the webs made by the ~uxkaposition of separate web hal~-thicknesses. Pre~erably, the concentration o~ long ribers ln each o~ the outermost 25~ sections o~ thic~ness is at leas~ 1.5 times the concentration o~ long ~ibers ln the central 50~ section o~ thickness and most pre~erably at !"
least two times said concentratlon. .;.
Addltional alternate embodlments of the ~:
present inventlon ~acing layers may be employed which utiliæe a singlc- transition ~abric which is ~oined at its ~hort fiber-enrlched ~clce to a second hal~-thiclcness ~ :
portion~ having greater structural stability than the pulp-enriched race Or the transition rabric. Among ~he alternate second halr-thickness port~ons Or particular :~
'....
'., ~
: ~9 ' ''. - ~ .

53~3 i~terest are: any one o~ ~1) a web o~ uniform blended composition throughout lts thickness) or either of two di~rerent ~orms o~ web3 of' non-unl~orm composition throughout thelr thickness, namely (2) a web having one outer race made o~ short ribers, the other ou~er ~ace ~ade oP long ~ibers and an intermedlate layer that ls a unl~orm blend of short and long ~ibers, or ~3) a web o~
~wo layers o~ ~lb~er~ one shork and one long, with the ~:
layer3 being interlaced only at their lnterrace.
10When the varlatlons (2) and ~3) are utilized as the sçcond hal~-thickness portion to be ~oined to the pulp-enriched ~ace o~ the transition fabric to make ~.
the ~acing layer, it ls the short ~iber ~ace o~ the second half-thickness portion that is ~oined to the transition ~abric so that the face with the longer ~ibers remains an outer ~ace in the composite.
In addition to the above products which can be used as the second half-thickness portion, the inventlon also contemplates t4) a thin layer made entirely o~ long fibers. ~he last-named embodiment ls not ordinarily pre~erred because o~ its expense.
It wlll be understood by those skilled in the art that-varlations and modi~ications o~ the speci~ic embod~ments descrlbed above may be employed without departin~ ~rom the scope oP the invention as de~ined in the app~nded claims.

~.... .

_30_

Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A multi-layer diaper comprising: a porous laminated facing layer to be brought into contact with the infant's skin, said facing layer including two juxtaposed through-bonded nonwoven half-thickness portions, each have-thickness portion having one major face facing out-wardly in said facing layer, a first of said nonwoven half-thickness portions being characterized by a given overall concentration of long fibers and short fibers, said first half-thickness portion having long fibers in excess of said given overall concentration at said major face facing outwardly in said facing layer, having short fibers in excess of said given overall concentration at the opposite major face, and having a transition of fiber concentrations between said major faces, and the second of said half-thickness portions being bonded to said first half-thickness portion at said face wherein the concen-tration of short fibers is in excess of said given overall concentration, said second half-thickness portion having at its major face, which faces outwardly in said facing layer, greater structural integrity than said bonded face of said first half-thickness portion, a highly porous, loosely compacted cellulosic batt in face-to-face juxtaposition with the outer face of said second half-thickness portion; and a water-impervious backing sheet adhered to the surface of said batt opposite said facing layer.

2. A diaper as set forth in claim 1, wherein said facing layer and water-impervious backing sheet are coterminous; said batt being smaller in dimension than said facing layer and backing sheet and centrally disposed there-between; and the marginal portions of said facing layer and backing sheet extending beyond said batt being adhered to one another.

3. A diaper as set forth in claim 1, wherein said second half-thickness portion comprises a non-woven material having at its outer face, a concentration of long fibers in excess of the concentration of long fibers at said bonded face of said first half-thickness portion.

4. A diaper as set forth in claim 1, wherein said second half-thickness portion is characterized by a given overall concentration of long and short fibers, said second half-thickness portion having long fibers in excess of said overall concentration at said major face and having short fibers in excess of said given overall concentration at the other face, and having a transition of fiber concentrations between said faces.

5. A diaper as set forth in claim 4, wherein the long fibers of said first and second half-thickness portions are different from each other.

6. A diaper as set forth in claim 4, wherein the long fibers of said first and second half-thickness portions are of the same fiber material.

7. A diaper as set forth in claim 4, wherein the short fibers of said first and second half-thickness portions are of the same fiber material.

8. A diaper as set forth in claim 4, wherein the short fibers of said first and second half-thickness portions are different from each other.

9. A diaper as set forth in claim 4, wherein the given overall concentrations of long and short fibers in said first and second half-thickness portions are the same.

10. A diaper as set forth in claim 4, wherein the given overall concentrations of long and short fibers in said first and second half-thickness portions are different.

11. A diaper as set forth in claim 4, wherein the con-centrations of long and short fibers at the faces of said first and second half-thickness portions wherein said concentrations are in excess of the given overall concentration for each half-thickness portion are the same.

12. A diaper as set forth in claim 4, wherein the concen-trations of long and short fibers at the faces of said first and second half-thickness portions wherein said concentrations are in excess of the given overall concentration for each half-thickness portion are different.

13. A diaper as set forth in claim 4, wherein said first and second half-thickness portions are of equal thickness.

14. A diaper as set forth in claim 4, wherein said first and second half-thickness portions are of different thicknesses.