Note: Descriptions are shown in the official language in which they were submitted.
. 3L195~(34
JBP 98
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
--2-
' '. .,~_.A
~s~
~. ~
JBP 98
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
-3-
3BP 98
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
-4-
~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.
- 6a -
: i
~95~
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;
- 6b -
,.,
~5~
JBP 98
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.
-7-
51~34
J8P 98
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
--8--
9~
JBP 98
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~
JBP 98
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
JBP 98
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
JBP 98
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
-13-
58~
JBP 98
; 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-
-14-
~ ~.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
-15-
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
-16-
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~
JBP 98
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.
-18-
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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.
--20~
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,
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JBP 98
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
-22-
JBP 98
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.
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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.
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