CA1195804A - Conformable disposable diaper having reinforced portions - Google Patents

Abstract

CONFORMABLE DISPOSABLE DIAPER HAVING REINFORCED PORTIONS

ABSTRACT OF THE DISCLOSURE

A disposable diaper having improved fit about the legs and/or waist of the wearer and having reinforced corners for enhanced securement of the diaper about the wearer is disclosed. Improved fit and reinforcement are obtained by an elongated, inherently elastic ribbon member positioned along at least one margin of the diaper. The ribbon member is secured to the diaper so as to provide an elastic region at a central portion of the margin and a unitary, relatively inelastic reinforced region in a corner portion of the diaper.

Description

. 3L195~(34 BACXGR W ND OF THE INVENTION

Disposable diapers ha~e become an arcepted substi~ute ~or cloth diapers and several different constructions have achieved significan~ market penetration.
Many of the disposable diaper configurations are rec~angular and flat, and comprise sheets which are fitted to a baby from a flat state. In some instances the diaper may incorporate a geometrical folding for shape. ~Two~ve~y serious drawbacXs with prior art disposable diapers ha~e been the problems of fit, both around the legs and around the waist of ~he infant, as well as the s~rength of ths diaper in the area where it is secured about the infant.
In solving these problems with disposable diapers, because of the nature of the product, the ~conomics are of primary impor~ance. The problem of fi~ is easily and simply solved merely by making marginal portions of the diaper elastic to improve the conformability about the legs of the infant and/or the waist of ~he infant. The problems of reinforcing the edge or corners of the diaper to make them stronger in their securement areas is easily and relatively simply solved by placing more layers of material in those areas. However, each of these operations will increase the complexity of the manufacture of the diaper and increase the cost of raw materials used in the diaper and hence substantially increase the ultimate cost of the diaper.
For enhanced fi~, in the recent past disposable ' '. .,~_.A

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diapers with contr~ctable si~e. ~laps which ga~her t~e side ~argins Q~ a diaper ha~e ~een intr~duced Into the marketr place. Such diapers are similar to con~entïonal moisture-impermeable panties and tend to improve t~e fit of the diaper abou~ the legs o the wearer, yet are costly to manufac~ure. A diaper of ~his general type is described in U~S. Patent 3,860,003.
There are also a number of pa~ents which disclose means for making the waist band of disposable diapers elastic to improve the fit of the diaper about the waist of the wearer, for example, as shown and describe~ in U.S. Paten~s 3,995,637 and 3,995,640.
Also, Yarious methods for ihcorpora~ing elastic members in garments to make portions of the garments 15 s~retchable are well known in the ar~. Such methods include the use of heat-shrinkable or heat-recoverable ilm ribbons which are incorporated into the garments while in a non-elastic state and then treated with heat to provide the ribbons with elastic properties or to accentuate the 20 elastic properties already present in the ribbons. Such techniques are g~nerally described in U.S. Patents 3,245,407 and 3,639,917.
Disposable diapers originally were secured with pins, but in recent times have been secured with pressure-25 sensitive adhesive tape fasteners or tabs. In both instances it is primarily the corners of the diapers which ~ake the stress in securing the diaper to an inan~
and continue to absorb s~ress during the in~ant's active pe~odsO The adhesiye tabs axe normall~ attached at one end tnereof at the sIde margins o~ the diaper and are secured to t~e relakiv~ly t~in ~rking ~heet of the diaper. Since the ~tress is ~reatest In thése areas, it has been known to xeinforce these areas hy various techniques~ for example, by the use of a scr~m adhered to the area, such as is dis-closed in U.S. Patent 3,867,940, or by thickening the backiny sheet in the ar~a of attachment as illustrated in~y.s. Patent 3,7831871. ~n either case regYstry pxoblems are encountered 10 during high-speed manufacture.

' SIJI!/IMA~ 0~ ~ lN'V~:N'l'10~
~ e ha~e d~scovered a new and improved disposable diaper which has Lmproved fit and at khe same time provides reinforced corner areas for enhanced securement of the diaper about the wai~t of the infant. Further, our new di~per is economical to produce, with a ~;~;mllm of extra manufacturing operations, and may be readily produced on high-speed equipment with good productivity.
In accordance with the present invention, our new and ~u~L~ed diape~ has at least one margin having an elongated, Inherentl~ elas~i:c r~on me~ber secured theretoO The ribbon r~embe:~ proY~des an el~s.t~c ~e~on at a central portion of the ~qa~gin and a ~n;~ta~;~y~r 27elat~Yely rtlel a~tic rei:nforced xe~on i~n a corner ~Q~tiOn of the di:aper ~ I n a pre~erred ~n~odimen~ of the d;~aper of the present ~nventi:on, each 25 longitu~l; nAl side margn of ~he diaper is provided with ~L9S!3694 ~BP g8 the r~bbon ~ember~ I:n another preferred elr~o~ nt, an add;~.ti;onal r~bbon m~nbe~ i:s prov~ded along one or both tran~ e e~d mar~nct o~ khe diaperO
Prefera~ly, the r~bon mem~er is a strip o~
which is of a w~dth o4 about 1/2" to 1'1 or more. The strip is interm~tent:ly sec~red to the backing and/or acing ~
in the central portion of ~:he diaper margin ~o maintain its elast~city; howeve3:, th~ end por . ions of the strip are continuously, preferably totally ~ over ~ubs~antially the entire ~urface area o the end portions ), secll~ed at the corner portions of the diaper whereby the previously elastic end portions of the strip are efîectively rendered ;nel~tic, and the strip reinforces the diaper in such regions.
lS In ~ thermoplastic fil~ ~rip t~e end por~ions may be rendered effecti~ely inelastic by applying heat or other bonding energy to the desired area of attachment~ The elastic pxop~rty in the unbonded portion or portions of the film, of course, remA i n~ undistllrbed . It is a relatively ~imple operation to ta~e a continuous, pre-~tretched length of an elastic film ribbon and adhere selected regions ~hexeof to the ~tandard impervious backing of a diaper during diaper manufacture.
Ano~her e~ually si~ple techn t que is to attach to the diaper marg~n ~ h.e~t~xg~ka~le ~lm rib~on which h~t~ rv~ elast~c t~nd contracts on ~eatin~ to a p~e~
deter~nt~ t~peratu~e. Suc~ lm r~b~on, whlle in ~he ~5-31 ~958~4 inelastic state, may be secured at end portions thereof along a diaper margin to the impervious diaper backing.
The central portion of the ribbon is heat-treated (e.g., with a hot air blast) to shrink the central portion and impart elasticity thereto.
According to another broad aspect of the present invention,there is provided a unitary disposable diaper comprising a first outer layer in the form of a moisture-impervious backing. An absorbent batt is positioned in superposed relationship with respect to the backingO A second layer, in the form of a moisture-pervious facing, is positioned in superposed relationship with respect to the batt. Side and end margins are formed by the batt by being shorter and narrower than the first and second outer layers. An elongated elastic ribbon member is disposed along substantially the entire length of at least one margin of the diaper. The ribbon member is secured in ~he margin. The ribbon member is secured in the central region of the margin to gather the said region. The ribbon member is secured at at least one end of the margin substantially continuously from the end of the central region to an outermost edge of the diaper.
At least one reinforced corner portion is provided by the secured end, which secured end is effectively inelastic.
According to a further broad aspect of the present invention, there is provided a method of forming a conformable garment having one or more discrete elas-ticized areas. The method comprises the steps of:
(a) providing a garment component having a central portion deined between two end portions;
(b) stretching at least one ribbon of thermoplas-tic elastomeric material;

_ ~ _ ,, (c) subjectiny at least one discrete portion of the stretched ribbon to heat so as to "kill" the elastic properties thereof in each heated portion whil~ leaving the elastic properties of each unheated portion unaltered, and ~ d) before, during, or after step (c), securing at least part of the stretched ribbon to the garment com-ponent substantially end-to-e~d of the garment component with one heated portion of the rib~on secured in an end portion of the garment component and with an unheated portion of the ribbon secured to the central portion of the garment component where~y, when the ribbon is permitted to contract with the garment component, the garment component central portion is elasticized to gather while at least one end portion of the garment component remains inelastic and ungathered.
According to still a further broad aspect of the invention, there is also provided a method for forming an elasticized disposable diaper having 1) at least one layer of sheet material with a central portion defined between two end portions and 2) thermoplastic ribbons of elastome-ric material attached lengthwise along opposite edges of the central portion of the sheet material in a manner in which the ribbons apply a gathering force in the central portion thereof. The method includes rendering end por-tions of the ribbons effectively inelastic by the applica-tion of heat to the ribbon end portions when stretched, and securing each ribbon end portion to substantially the entire length of an end portion of the layer of sheet material before, during, or after the application of heat.

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The foregoing expedients simultaneously produce a diaper having both improved fit and reinforced corner areas for enhanced securement of the diaper about the infant.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings:
FIGURE 1 is a perspective view illustrating a disposable diaper embodying the present invention;
FIGURE 2 is an exploded perspective view showing relative positioning of diaper elements during manufac-ture of the diaper depicted in Figure l;
FIGURE 3 is a perspective view of another embodiment of the disposable diaper of the présent inven-tion;
FIGURE 4 is a perspective view showing still another embodiment of the disposable diaper of the present invention;
FIGURE 5 is a plan view of one embodiment of a disposable diaper of this invention with a portion broken away to show interior detail;

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FIGURE 6 is an enlarged cross-sectional view take~ alon~ line 6-6 of Figure 5;
FIGURE 7 is an enlarged cros~-sec~ional view taken along line 7-7 of Figure 5;
~IGURE 8 is a plan view o~ another emko~;m~nt of a disposable diaper o~ ~his invention with ~ portion broken away to show interior detail;
FIGURE ~ i~ a plan view of still ~ fu.rther embo~ i ~nt of a disposable diaper 9f this invention with a portion broken away to show interior detail; and FIGUR~ 10 is a plan view of an additional embodiment o~ a disposable diaper of ~hi~ invention with a portion broken away to ~how interior detail.

DESCRIPTIO~ OF T~E PREFERRED EMBODIMENT~
In one pxeerred embodiment o~ the disposable diaper of the presen~ invention, the elastic means and reinforcing means ic a member which is elastic iR itS
original state and may be relaxed or have its el~sticity rendered inefective in selected portions by heat sealing or ultrasoni~ally sealing those portions to the diaper backing and/or facing. ~any thermoplastic films are well known in th~ art which have this property, and are described in detail hereafter.

51~34 The term "elastic," as used herein, refers to ~heets, films, r~hhon.s and the like which have a recovery of at least 90 percent, when elongated to within 10 percent of their yield point and measured in accordance.wi~h ~he following formula:

Percent retraction , Le - ~t X 100 ~e _ L
where ~.

Lo 2 original length of sample Le = fully ex~ended length Lt = length of sample measured 3 seCon~ after released from ex~ended length.

The member used should have a width of at least 1/4 lnch in the areas of the diaper where it is to be used as a rein~orcing means. It is preferred that the entire length of the member be at least 1/4" wide and preferably 1/2" to 1" wide. The ~hickness of the member may vary from bout 1/2 mil ~o 10 mils ~nd is preferably between about 1/2 and 5 mils.

The elastic means has a recovery at 50% elongation aftPr 3 seconds and pre~erably instanteously of at least about 90% and preferably close to 100%. For ease of stretch-ability, the dulus o~ elasticity of the elastic means at 50% elongatio~ should not exceed about 2,000 lbs. per 9~

The modulus o~ el~tic;ty ~s preerably subs~antially l~s ~han 2000 po~nd~ ~er square ~n~h~ and most preferably ~s about ~0 to about 2~0 pounds per square ~nch. The elastic mean~ may ~e used along both longitl~;n~l side margins o a . disposabl~ ~ t.Ap~ and~or along one or both front and back end portions of the diaper as desired.
R~erring to Figure 1! a disposable diaper 20 embodying the present invention is provided wi~h longitu~; nA 1 side margins 21 and 2?. The central portions 23 a~d 24 of each LO side margin i5 elastic to provide Lmpro~ed fit about baby's ~highs~ At both ends of each longitl-~; nAl side margins are non-elastic, reinforced corners 25, 26, 27~ and 28~ The elastic means ln each of the longit~l~;n~l side margins is a relatively wide, thin elastic film ribbon. The film ribbon has been relA~ed and its elasticity xemoved at both ends of ~he ribbon to reinforce ~he corners. The diaper additionally includes a first outer layer, or backing, made of a moisture impermeable web, a generally rectangular absorbent batt posi~ioned in superimposed rela~ionship with re~pect to the ~0 h~Ck; ng and a second outer layer, or facing, m~de o~ a moisture-permeable web and positioned in sup rposed relationship t~7 the ab$c7rbent batt ~ ~or securement about a baby, tEle d~apex i~ ~?r~r~ded with pressure-sens.2t ~ e t~pe ta~s 32 and 33, Tne elastic srlembers are generally _g L95~

paralld to the long.atudianl side margins of the batt.
The ends are treated to remove elasticity so that when the diaper is re~ the central portion of each side margin contracts and is elastic while the four corners are non-elastic but are reinforced with additional film material.
The individual components of a disposa~ie diaper are illustrated in Figure 2. Absoxbent batt 35 is superposed over the ther~plastic film backiny 36 and ~.ecured ~hereto by a serias of glue lines 37 deposited on the b cking. The absorbent batt is of smaller area than the backing and when ~ubstantially centered on the back; ng is spaced from the longitu~; n~ 1 sides as well as fxom the transverse ends of a diapex. The absorbent batt is flanked on its longitl-~; n~l sides by members 38 and 39 which in an extended state are secured to the backing by means of a~ adhesive,sonic sealing or other con~enient means~
Moisture-pervious facing 40 is superposed over the absorbent batt and is lar~er in area than the batt and is secured to the b~ck; ng usually by means of the exposed end portions of the glue lines; however, other securement means may be utilized if desir2d. It should be noted that the elastic ~ilm members may be secured to either the backing or ~acing or both as desired.

S~3~4 ~P3 98 ~n the manufacture of the diaper, only the.
cantral portions 41 and 42 o~ the elastic film members are allowed to remain elastic. This may be accomplishëd ~hen using sonic sealing by sealing intermittently and/or in a pattern. The end portions 43 are txeated with heat, ultrasonics, or similar energy ; n~lCi ng means, to Le..,~ve the elasti~ity of the film in those areas. ~ -;"
Figure 3 shows a disposable diaper 44 sim;1~r to the dicposable diaper depicted iA Figure 1 with the exception that the elas~ic means and rein~orcing means are in the back waist or end:portion 45 of ~he diaper ~o provide improved fit about the babyls waist. The elastic means and reinforcing means in this diaper is similar to that described in regard to ~igure 1 and is a film ribbon treated as pre~iously described so as to perfonm in the same manner ; i o e., the central portion 46 of the end portion is elastic while the two back corners 47 and 48 are rein~orced~
Figure 4 shows yet another disposable diaper 51 similar to the disposable diapers in Figures 1 and 3, with the exception that all foux edge portions, that is~
the two longit~;n~l side margins 52 and 53 and the fxont 54 and 55 end margins, all have film ribbon ~mh~rS
inserted therein with the central portions thereof - ~LY15~4 ela~tic? In th~s emkod~ment t~e four corners, 56~ 57, 58 and 59, are doubl~ re~n~oxced by the overlapping of ~he rel~e~ end po~tions of eac~ film ribbon mem~erO
~n ~he ~b~d~ent ~hown in Figure 5 a disposable S diap~r 60 i~ prQ~ded Wi~h a 3ubstantially rectangular batt 61 or panel having rectiline~r sides sandwiched betwee~ a backing 62 and a ~acing 63 and together with the backing and facing define diaper side margins 64 and 65. Cur~iline~r rutouts are provided in th~ respective cen~.ral portions of the side ~aryins of ~he ~acing and ~A~k; ng for ~urther fit-e~hanc~ment.
; Pre-stretched ela~tic ribbons 68 are positioned in the longitl~i n~l ; ~ide margins and are secured to ~he ~ck;ng and facing along the longit~ sides of the absorbent panel. The elastic -ribbons ha~e been relaxed at each end 59 and 70 to provide reinforcing areas. Glue lines 71 secure the facing and absorbent panel to the ~ck; ng and adhesive tape tabs 7~ and 73 provide diaper securement means. The adhesive tape ~abs over-lap the relaxed reinforcing ~reas of the ribbon to provide ~his area, which absorbs the most s~ress in use, with extra material to improve the strength of this area.
Referring to Figure 6, which is a cross-sectional view taken al~n~ l~ne 6-6 of Figure 5, there is shown ~h~ ~mp0rv~us backin~ member 62 with the elastic ri.~bon 68 s-ealed ta th~ hack~n~ ~emher, The ~ibbon i:s sealed along tw~ ~.rn~sus~l~ne ~Xt~o~ 74 and 75 to the backi~y member~

~12-5~4 and the facing layer in the central portion as shown in Figure S.
~ s seen in Figure 7, which is another cross-~ection view at the corner of the diaper, the ~hes;ve tape tab 72 attached to the backing member 62 is also attached to the facing member 63. The ~ape tab area is reinforced with the non elastic reinforcement portion 6g of member 68.
In the embodiment shown in Figure 8, the disposable diaper 80 is provided with the absorbent batt 81 also having curvilin~ar ~ide cutouts and sandwiched be~ween a ~acing 82 and a backing 83 having s;mi 1 ~r cutouts. G1UQ lines 84 serve to secure the batt and facing to the backing. Wide elastic ribbons 85 are situated in the general rectilinear diaper side margin~. The elastic ribbons e~tend the entire length of the diaper side margin and are intenmittently secured to the backing and facins at the central portion 86 thereof to provide ~he desired elasticity. In the outer portions 87 and 88 the elastic ribbon has been rel A~P~ and made non-elastic. Protruding portions 89 and 90 of the absorbent batt overlap the entire width of the rel~xe~ ribbons ~o provide additional absorbent capacity. ~he tape tabs 91 and 92 overlap the reinforced ends of the rel~ed elastic member and are reinforced thereby. The tabs provide the means for securing the diaper to the baby.
25I~ the embodiment shown in Figure 9, the disposable diaper 100 of the present invention comprises an impervious backing member 101 and an hourglass shaped absorbent pad 102 58~

; b~ing narro~ ~n the crotch area 103 of the diaper, and a top : ~acing lay~ 104~. ~n th~s conXigura ion the top layer and ~mpervious ~ck;ng member form areas 105 and 106 as part of ~h~ ~ide maxgins, These areas of ~he ~ide margins contain no absorbent core material. This xeduces the bulk of material b0tween t~e baby's legs. In each side marsin of ~he diaper, ~here is inserted be~ween the impervious backing and pervious facing layer the elastic member 109 which has its central portion 110 ela~tic and its t~ ~nd ~10 portions 111 and }12 ralaxed or mad non~elastic for re-inforcement.
The diaper has an hourglass shaped absorbent body wherein the absorbent body in ~he wais~ portion is wider than the a~sorbent body in the crotch area. At the b~ck waist portion of the diaper are adhesive tape tabs 113 and 114 which have been adhered to the portion of the backing mamber which is reinforced.
The e~bodiment shown in Figure 10 is a disposable diaper 120 that compri~es a rectangular i~pervious h~k; ng member 121 with a smaller area of absorbent core 122 adhered thereto with glue l~nes applIed to the backing member. On top of the absorbent core i:s the ~acing member 124 which is co-extens~ye wi~th the b~ck~n~ ~e~be~ to form the lon~it~ld;n~l 8i~.d~ margins 125 and 126 and t~.e end marg~ns 127 and 128, ~dhered ~etween the ~ack~ng and fac~ng me~bers at ~ne back wa~t margi.n 127 is~ the member 129, The member i~ elastic ~n the central port~on 130 and has been relaxed and made non-~ ~.95~

elastic a~ the ~wo edge pQrtions 131 and 13Z. A s ~ilar elast~c mem~er ~ ma~ b~ ~nserted at th~ ~ront wai~t port~on 128 o~ t~e diape~. Adhesive tape ta~s 133 and 134 are adhered ~o the backin~ mem~er in the reinforced portion thereof and are used fo~ securem nt about the baby.
~ lastic members that lose their elas~icity on heat se~li ng and su~table ~or use in ~he diapers contemplated herein are films ~xtruded or o~herwis~ ~ormed to the desired thickness utilizing ~vulcan~zed, thermoplastic compositions which are made using an elastomeric component and .a~n op~ional compatible modi~ier which is a thermoplastic polymer of a relatively lo~ molecular weight but solid at am~ient temperature.
Illustrati~e of the elastomeric component~
sui~able for present purposes are block copolymers which comprise kerm; n~ 1 thermoplastic pol~mer blocks and at least some non-t~r~in~l or inter~ ate elastomeric pol~mer blocks. Block copolymers of this general ~ype m y be prepared using a step-wise polym~rization initiator, e.g., an organolithium compound.
Such block polymerization technigues are well known in the art~
The elastic co~ponent can be linear or radial Al-B-A2 block co~olymex$ or ~xtures ~hereo~ with simple Al-B block copoly~ers ~h.e~eIn ~1 and A2 can ~e al;~ke or d~erent and repres:ent a the~moplast~c polymer ~lock, such as. poly~ Lv~nYl a~eneL ~loc~ ~nd B represent~ an elas.tomeric polyme~ ~lock such as a con~u~ated dlene or a lo~er ~i,e., Cl-C4) alkene~ The modIfIer component is a low molecular weight JBP 9~

plastic csmpositions which are made up of an elastomeric component and an optional compatible modifier which is a thermoplastic polymer of a rela'cively low molecular weight bu~ solid at ambient temperature. ,-Illustrati~e of the elastomeric components sui~able for present purposes are block copolymers which comprise terminal thermoplastic polymer blocks and at least non-terminal or intermediate elastomeric polymeric polymer block. Block copolymers of this general type may be prepared using a step-wise polymerization ini~iator, e.g., an organoli~hium compound. Such block polymeriza~ion techniques are well known in the ar~.
The elas~ic component can be linear or r~dial Al-B-A2 block copolymers or mixtures thereof with simple Al-B block copolymers where Al and A2 can be aliXe or different and represent a thermoplastic polymer block, such as poly (~inyl arene) block, and B represents an-elastomeric polymer block such as a conjuga~ed diene or a lower (i.e., Cl-C4) alkene. The modifier component is a low molscular weigh~ thermoplastic polymer having an average molecular weight of about 500 to 7,500 and is present in the composition in an amount of about zero to about ~00 parts by weight per 10~ parts by weigh~ of the elastomeric component.
A preferred thermoplastic film composi~ion or 58~

3BP g ~he el~stic ~ilm members comprises an el:ast~m~r;c ~o~ onen~
wh~c~ contaIns, as a major const~tuent thereof~ an - u~Yulcani~zed 1 ~n~r ~lock copolymer of the general configuration Al ~ B, ~2 wherein Al, A2, and B have ~he same meaning as her~; n~bove.
In these block copolymers the A-blocks are derived from styrene or ~tyrene homologues, and the B-blocks are derived from co~jugated dienes or lower alkenes. The ~hermoplas~ic polymer modifier is compatible with the elastomeric component and associates princ~pally with ~he thermoplastic ~rmi n~ l blocks of the aforesaid unvulcanized block copolymer. The thermoplastic polymer mod fier preferably has an average molecular weigh~ of about lOOO-to about 3000, and i5 presen~
in the film composition in an amount of about 80 to 200 parts by weight per 10 0 parts by weight of the ela~tomeric 15 component.
The preferred A -B-A2 block copolymers have A-blocks derived, i.e., polymeriz~d or copolymerized, from styrene or styrene homologues; and B-blocks derived from conjugated dien~, such as isoprene or butadiene, or Prom lower alkenes, s.uch as ethylene ~nd butylene. Small proportions of othe~ mQno~er~ als.o may enter i:nto the E~lock copol~mers themsel~,re~. The i~ndi~v~.dual. A~blQcks can have an a~era~e malecul~r wei~ht o~ ~t lea~t al:is)ut 600Qr preferabl~ in t~e :ran~e Q~ a~out 8QQQ ~ 30~QQQ, and t~e A~locks ~-17--s~o~

constitute about 5-SO percent, preferably about 10-30 percent, by weight o~ the block copolymer. The average molecular weight of ~he B-blocks for linear Al-B-A2 block copolymers preferably is in the range of about 45,000-180,000 and that of the linear copolymer, itself, preferably is in the range of about 75700Q-200,000.
The a~erage molecular weight of the radial Al-B-A2 block copolymers preferably is in the range o.about 125,000-400-OOQ. The term "linear block copolymer"
tor copolymers) includes branched Al-B-A2 copolymers as well as unbranched Al-B-A2 copolymers.
.. The radial Al-B~A2 copolymers useful for manufacture of elastic members or diapers of this invention are of the type described in United States Letters Patent No. 3,281~383 ~o Zelinski et al and conform ~o the following general formula: (A-B-nX), wherein A is a thermo-plastic block polymerized from styrene or styrene homo-logues, B is an elastomeric block derived from conjugated dienes. or lower alkenes 7 as indicated above, X is an or~anic or inorganic connect~g molecule, with a functionality of about 2 to 4 as described in Patent No. 3,281,383, or possibly with a higher functionality as described in the Article entitled "New Rubber is Backed by Stars" appearing on page 35 of the June ll, 1975, issue of Chemical Week~ As used hereinabove, 'tn" has a value correspond~ng to the functionality of X.

s~

J~P 98 The preferred elastic ~ilm member ~s highly them~plastic and, thou~h.elaskomeric, i~ unlike rubber in ~hat the fil~ ~Y~ih;ts a relatively sharp melting poin~
. and i capable of being heat shaped. Also, the elastic film member can for~ per~anent heat seals to su~strates such as non ~voYen ~abrics~ or the like, at relatively low heat sealing temperatures, generally not above abou~ 350F. The film member is highly elastic and has a relatively low rubber modulus, i.e., it exhibits in at least one direction an elastic recovery from 50 percent stretch to at.l~st 75 percent, ~prPferably at least about 80 percent, and a 5û percent rubber modulus of not above about 2000 poun~s per^square inch, preferably in ~he range of about 20 to about 200 pounds per square inch at 50 percent elongation. ~he ~ilm member also is very flexible, extensive and so~t and normally ~hi ~; ~S a Gurley stiffness of about one or less at a film thicknes~ of one mil, and an elongation to break of at least about 300 percent, preferably at least about 400 percent, in a~ least one direc~ion at ambient ~emperature.
In some embodLments of the disposable diaper of the present inYentiOn, ~he elastic means and reinforcing means is a ~ember whi:ch may be made elastic by imparting heat or other for~s o$ enex~y to the mem~er to shrink the m~m~er and pr~vi~de i~t w~th elast~c characteristics~ A

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~ ~1958l~

~BP 9 8 portion o~ the men~ber i:s so ~eated ~o pro~ride the elastic mean~ wh~le other port~ ons are not trea~ed ~nd pro~ide ~he rein~orc~ ng mean~.
The heat shr;nkAhl e films which may be used as elastic members in the disposable diapers sf the prese~Lt in~ention ~y be the polyole~in films which have been oriented to a degree and which will then become elas~ic when heat shrunk. Usually, a preferred ~echnique for orien ing the O polyeth~lene film to provide the heat shrunk ~lastic prop0rtles is by ixradiation such as suggested in British Patent 866,8~0~ Also, useful as the heat shrunk elastic members are the copolymers of ethyle'ne and vinyl acetate, ethylene and ethyl acrylate, and ~he like. The forming of such copolymers i~ well known and specific methods of ~orming such materials are disclosed in U.S. Patents 2,200,429 and 2,953,551. After the copol~mer is formed and made into a film, it is given the proper orientation as described in the previously-mentioned British Patent 866, 820 .
Several different types of facing materials may be u~ed for the diaper faci~g, for example, the acing may be a non~wo~en web m.~de o~ a mixture of fibers con~isting pre~m;nAtely o~ ~hort~ cellulosic ibers such as wood pulp fi:ber~. or co~ton l~;nters ~n amounts of 75% to about 98%, th~
~1.AnCe being textile len~th. ~ber$ such as rayon as described ~n U~, patent 3,633~348 ~o ~i~lo~,a et al.

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9L958~

JsP ~ 3 Non~woven ~acing materi~als su~table ~or use in di~.posable di:a,pers of ~hi;s in~ent on can ha~e abric wei~hts ~n the range of from a~out 0~ 5 to 5 ouncesf per square yard and dens~tIIes of less ~Aan . 15 grams~cc ., yenerally in the r~nge csf about . 05 to .1 gram~cc. The dry s~rength of the facing ~heet for fabr~c ha~ing a weight of about .15 ounces par sguare yard is at least .15 lbs. per inch of width in th~3 machine direction. Such ~abrics have good elongation, loft, softne 5 and drape characteristics. Facings may also be made of an apertured non-woven fabric ^whic~ is formed, ; for example, in accordance w~th the teachings of commonly assigned U.S. Patent ~os. 2,862,251; 3,081,514; and 3,081,515. Briefly, such fabr;c~ are ~oraminous structures wAerein groups of fibers ; have been rearr~nged from a non-wov~n star~ing web ~o posi~ions uLLounding less dense ~abric port~ons by pa~sage of fluid through the starting material. The fibers within the groupings are interlocked a~d may be arr nged in various pattPrns as is well known in khe art. These fibers can be made of na~urally o~curing fibers, syn~he~ic fibers or blends thereof. Typical $acing sheets made of polyester type fibers may have a weight of about .75 ounces per sguare yard.
The facings ma~ be the sa~e size as, and cotPr~;nous ~ith. th.e hAck;~; o~ alternatIyely, the ~acing ma~ be wider than the ~ckln~ and ~e ~it~ ~ide edges inwardly folded so that th.e ~aci~n~ ~s c~te~ rous ~ith the back2ng~ as is shown .n Fi~ure 3 of U.~. ~atent No, 3~.612~.Q55. ~n the latter case, the elastic me~ers. may ~e Qecured above the inwardly foldsd ~de edge~. Q~ ~he facing, ~n addit~on, ~acings. can be ~ormed of non-apertured ~ater~als su~h a~ non-woven iso~ropic web~ or apertured polyolef~n or polyester films having the desired moisture permeability. In all of th~ afore~entioned ~ac.ings, the material should be relatively hydrophobic so as to retard wicking within the facing, The moisture absorbent batt or panel of a desired shape~ but smaller than the facing and the h~k; ng, can be formed in accorda~ce with the teachings of U.S, P~tent No.
3,612,055 to Mesek, et al.
A suitable ~ack; ng material or the diapers embodied in the presen~ invention can be an opaque polyolefin, for example, polyethylene about .001'~ thick. Another ~ui~able material ~or this purpose is a polyethylene terephthalate having a thicknes~ of about .0005".
Perhaps the simplest and easiest way of adhering the elas~ic film member to the film and ~acing along the longitufli na~ side portion of the diaper is to ultrasonically weld it in or weld the various layers ~oge~her using ul~rasonic wel~ing equipment such as that sold by the Branson Sonic Power co~ ny~. q!wo p~s~ble method variations may be used for ult~a~oni:cally~eld~n~ the ~ember to the d~aper. In the ~Xst ~et~od the central p~rt~Qn o~ the elast~c ~ s -~on~call~ ~ealed ~n an i~ntermittent patte~n~
. and t~.~ end port~ns heait sealed throu~hQut kheir area. ~n the second method the entire ilm member is so~ically sealed with high enexgy applied to the end por~ions to s~al their entire sux~aceO In both techniques the film is heated at its end portions to a point where 5 it almost melts and loses sub~tantially all of its memory and is ~hus non-elastic in those areRs. The elastic o~h~r may be ultrasonically welded to the backing and/or the facing ~s desired. ~ - ~
While the elastic film ~ Prs described above are in the fo~m o~ members which lose ~heir elastisity upon the application of heat or other energy, the presen~ invention is not limited ~hereto, and memb2rs which become elastic upon the application of heat or other e~ergy may also be used. Films which shrink and become elastic when hsated are well known ~nd may be used to produce diapers in accordance with the presenk invention. Such a heat shxinkable film member may be inserted in a diaper margin and a portion o ~he member adhered to the diaper as by gluing. A~o~her portion of the member is intermi~tently secured to ~he diaper. Upon the applica~ion of heat or other energy to ~he intermi~tently secured portion, the portion ~hrink~ and becomes elas~ic. The adhered glued poxtion remains in place and ac~s to reinforce the diaper in ~ha~ area.

g~

JsP 98 The ~oregoing description and ~he drawings ase iIlustrative and are not to ~e taken as limiting.
Still o~er ~ariations and modifica~ions are possible.
without departing ~rom th~ spirit and s ::ope o:E tht~
5 present invention.

Claims (19)

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

1. A unitary disposable diaper comprising: a first outer layer in the form of a moisture-impervious backing, an absorbent batt positioned in superposed relationship with respect to said backing, a second layer in the form of a moisture-pervious facing positioned in superposed relationship with respect to said batt, side and end margins formed by said batt being shorter and narrower than said first and second outer layers, an elongated elastic ribbon member disposed along substantially the entire length of at least one margin of the diaper, said ribbon member being secured in said margin, said member being secured in the central region of the margin to gather said region, and said member being secured at at least one end of the margin substantially continuously from the end of the central region to an outermost edge of the diaper, and at least one reinforced corner portion provided by said secured end, said secured end being effectively inelastic.

2. A disposable diaper in accordance with claim 1 wherein said elastic ribbon member is a thin, thermo-plastic film.

3. A unitary disposable diaper comprising: a first outer layer in the form of a moisture-impervious backing, an absorbent batt positioned in superposed relationship with respect to said backing, a second layer in the form of a moisture-pervious facing positioned in superposed relationship with respect to said batt, side and end margins formed by said batt being shorter and narrower than said first and second outer layers, an elongated elastic ribbon member disposed along substan-tially the entire length of each side margin of the diaper, said ribbon member being secured in said side margin, said member being secured in the central region of the margin to gather said region, and said member being secured at at least one end of the margin substantially continuously from the end of the central region to an outermost edge of the diaper, and at least one reinforced corner portion provided by said secured end, said secured end being effectively inelastic and at least one end of the diaper being provided with two reinforced corner portions.

4. A disposable diaper in accordance with claim 3 wherein said elastic ribbon member is a thin, thermo-plastic film.

5. A disposable diaper in accordance with claim 3 wherein the first and second outer layers are substan-tially rectangular and generally coterminous with one another.

6. A disposable diaper in accordance with claim 3 wherein the first and second outer layers are hourglass shaped and generally coterminous with one another.

7. A disposable diaper in accordance with claim 3 wherein the side margins are each wider in the central region than in the corner portion.

8. A unitary disposable diaper comprising: a first outer layer in the form of a moisture-impervious backing, an absorbent batt positioned in superposed relationship with respect to said backing, a second layer in the form of a moisture-pervious facing positioned in superposed relationship with respect to said batt, side and end margins formed by said batt being shorter and narrower than said first and second outer layers, an elongated elastic ribbon member disposed along substantially the entire length of each side margin of the diaper, said ribbon member being secured in said side margin, said member being secured in the central region of the margin to gather said region, and said member being secured at at least one end of the margin substantially continuously from the end of the central region to an outermost edge of the diaper, and at least one reinforced corner portion provided by said secured end, said secured end being effectively inelastic providing reinforced corner portions at one end of the diaper, and securement means for secur-ing the diaper about the waist of the wearer, said secure-ment means being attached at one end at the side margins of said diaper in the reinforced corner portions of the diaper.

9. A disposable diaper in accordance with claim 8 wherein the securement means are adhesive tabs.

10. A method for forming a conformable garment having one or more discrete elasticized areas, said method comprising the steps of:
(a) providing a garment component having a central portion defined between two end portions;
(b) stretching at least one ribbon of thermoplas-tic elastomeric material;
(c) subjecting at least one discrete portion of said stretched ribbon to heat so as to "kill" the elastic properties thereof in each heated portion while leaving the elastic properties of each unheated portion unaltered;
(d) before, during, or after step (c), securing at least part of the stretched ribbon to said garment com-ponent substantially end-to-end of the garment component with one heated portion of the ribbon secured in an end portion of said garment component and with an unheated por-tion of the ribbon secured to the central portion of said garment component whereby, when said ribbon is permitted to contract with said garment component, said garment com-ponent central portion is elasticized to gather while at least one end portion of said garment component remains inelastic and ungathered.

11. A method in accordance with claim 10, wherein step (d) includes bonding said ribbon to said garment component.

12. A method in accordance with claim 10, wherein step (d) includes securing said one heated portion of the ribbon to said garment component end portion at spaced lo-cations along said garment component end portion.

13. A method in accordance with claim 10, wherein step (d) includes securing said one heated portion of the ribbon to said garment component end portion substantially continuously along said garment component end portion.

14. A method in accordance with claim 10, wherein step (d) includes securing said one heated portion of the ribbon at the distal end of said garment component end portion.

15. A method in accordance with claim 10, wherein step (c) includes subjecting at least two spaced-apart discrete portions of said ribbon to heat so as to "kill"
the elastic properties thereof in each heated portion while leaving unaltered the elastic properties of each unheated portion between said two spaced-apart discrete portions and in which step (d) includes 1) securing one of said two spaced-apart unheated portions of said ribbon to one end of said garment component and 2) securing the other of said two spaced-apart unheated portions of said ribbon to the other end of said garment component.

16. A method in accordance with claim 10, wherein step (a) includes providing said garment component as a diaper sheet material in which said central portion is a crotch portion of the diaper sheet material and in which each said end portion is a waistband portion of the diaper sheet material.

17. A method in accordance with claim 10, wherein step (a) includes initially providing said garment component in a continuous web and in which step (b) includes initially providing said ribbon in a continuous length.

18. A method for forming an elasticized disposable diaper having 1) at least one layer of sheet material with a central portion defined between two end portions and 2) thermoplastic ribbons of elastomeric material attached lengthwise along opposite edges of the central portion of said sheet material in a manner in which said ribbons apply a gathering force in the central portion thereof, said method including rendering end portions of said rib-bons effectively inelastic by the application of heat to said ribbon end portions when stretched, and said method including securing each said ribbon end portion to subs-tantially the entire length of an end portion of said layer of sheet material before, during, or after said application of heat.

19. A method in accordance with claim 18, wherein said step of securing each said ribbon end portion includes securing one said ribbon end portion to substantially the entire length of an end portion of the layer of sheet material at spaced locations along substantially the entire length of the end portion of the layer of sheet material.