Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
The present invention relates to improvements in dis-
posable diapers which enable the diaper to closely conform to
the torso of a baby, without sacrificing absorptive capacity.
The diapers of the present invention accomplish this without
causing any disco~fort to the baby, while at the same time
providing improved gasketing around the thighs and resultant
fluid containment.
In the recent past disposable diapers have been
introduced into the market place which have a narrow but
relatively thick strip of elastic at each side thereof, so
as to gather the side margins of the diaper in a manner simi-
lar t. that of conventional moisture-impermeable pantles.
Such diapers are made generally in accordancé with the teachings
of U.~. Patent No. 3,860,003. In order for the elastic
membe~-s to be effective in such diapers, it is necessary that
the e astic members be spaced relatively far from the side
margl-.al edges of the absorbent panel of the diaper, and
for he elas~ic members to be associated with thin, highly
fleY.~`~le facing and backing layers. As a result, when
such . apers are placed upon a baby, the narrow but relatively
thick elastic members cause a narrow band of the facing layer
to bear against the baby's skin with substantially line
contact. This results in a high degree of stress concentra-
tion that may cause pinching and irritation of the baby's skin.
The problems attributable to the unduly high co~pres-
sive force caused by such narrow but relatively thick elastic
strips of the prior art diapers mcntioned above are particularly
acute when the baby has voided and the diaper is wet. Because
the backing and facing layers are so hi5hly flexible, when the
diaper is wet and conditions are present ten~ing to cause hvdration of
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he baby's sr.in, the narrow elastic members sometimes caus~
the facing layer to press against the skin with sufficien_
force to injure the skin. Also, the elastic members in prior
art diapers of the type described above cause the diaper to
gradually creep upwardly upon the baby's thighs. As a result,
the forces applied to the skin by the stressed elastic members
increase the longer the diaper is worn.
One of the most serious drawbacks with prior art
diapers of the above mentioned type is that in order to give
the diaper sufficient flexibility at the sides to permit
gathering, the absorbent panel has been narrowed in the mid-
portion, cr lightened to such an extent that the absorbent
capa- ty of ~he diaper in the critical area is significantly
reduced.
While many attempts have been made in the past to
pro~lde diapers, both disposable and non-disposable, with im-
pro~ed fit characteristics without sacrificing absorptive
capac~ty, heretofo~e such efforts have not met with success.
Su.~-~ary of the Invention
In additior: to those elements which are present in
currently commercially available products, i.e., a moisture
pervious facing adapted to engage the baby's skin, an absorbent
batt or panel adjacent to the facing, and an outer moisture
impervious backing over the absorbent batt, the diapers of the
present invention include constringent means at each side of
the diaper which are effective to not only gather the longitu-
dinal margins of the diaper, but also to reduce the length of
the side margins of the absorbent panel and create pillow-like
marginal bulges therein. In the preîerred embodiment, the
constringent means is provided by relatively wide, but thin,
~ l5~1S2
lastic ~embers that are secured to he bas'~ing ar.~/o- ac~g and are
~ t~d s~~ici~tly clo~ely ~o the ~ide m~rgins o~ the ab~or-
bent panel so that constringing forces generated by the
elastic members are trans~itted to the sides of the absorbent
panel at least through the backing, ,hereby causing the sides
of the absorbent panel to buckle and/or bulge. By the term
"relatively wide," the present invention contemplates that
elastic members have a width of at least 1/4", preferably a
width of at least 1/2", and more preferably a width from about
3/4" to about 1 1/4". The width-to-thickness ratio of
the preferred constringent means is at least about 100.
It is contemplated that the relatively wide elastic
me~ ers may be provided by two or more rel=tively narrow (1/~"
or less) elastic members that are positioned in spaced parallel
rela_ionship with respect to one another, and which cooperate to
f~nc~ion as though they are essentially one elastic member havlng
a wid~h dimension that is measured between the outer edges of
t_h- outer elastic members. And, it is also contemplated that
th r--latively wide elastic members may be provided by round,
;-,r f!attenedelastic t~es, woven bands, retic~a.ed bands, or elastic monofila-
ments that are arranged to provide tne desired force distribution.
Diapers constructed in accordance with the present
invention have several unexpected advantages, particularly
as compared to the prior art diapers of the type disclosed in
U.S. Patent No. 3,860,003. In this regard, by utilizing relativelv
wide elastic members as the constringent means, the area of the
facing that is pressed against the baby's skin is relatively
large so as to distribute the force ap~lied tO the skin over a
relatively large area and to minimize the possibility of irri-
tation. Because of the relatively large area of facing engas-
ing the baby's skin and the bulged side margins of the panel,
improved gaske~ing around the thighs is effected, therebv
Z
minimizing leakage from the diaper. In this regard, it is
significant that absorptive materials effect at least in
part the gasketing action, in contradistinction to the
relatively non-absorbent facing in U.S. Patent ~o. 3,860,003
which provides little, if any gasketing action.
As will appear in more detail from the following
description, diapers of the present invention provide improved
fit, and improved gasketing (or sealing) around the baby's
legs, without loss of absorptive capacity and without irri-
tation to the baby's skin.
According to a broad aspect of the present invention
there is provided a disposable diaper comprising a first outer
layer in the form of a moisture impervious backing with an
absorbent batt positioned in superposed relationship with
respect to the backing. The batt is smaller than the backing
and spaced inwardly from the sides and ends thereof. A second
outer layer in the fonn of a moisture pervious facing is
po itioned in superposed relationship with respect to the
batt. The facing is larger than the batt and has marginal
portions thereof secured to the backing. Constringent means
is provided in eash side margin of the diager for foreshorten-
ing the side margins of the diaper. The constringent means
cooperates with the outer layers and the batt to bulge the
side margins of the batt, in addition to gathering the side
margins of the outer layers adjacent thereto.
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Brief Description of the Drawings
In the drawings,
FIGURE 1 is a perspective view illustrating a
disposable diaper embodying the present invention with a
portion broken away to show interior detail,
FIGURE 2 is an exploded perspective view showing
relative positioning of diaper elements during manufacture
of the diaper depicted in FIGURE 1,
FIGURE 3 is a perspective view of the diaper of
FIGURE 1 illustrating diaper configuration when applied
about a baby;
FIGURE 4 is a perspective view showing another
embodiment of the disposable diaper of this invention;
FIGURE 5 is a sectional view, on an enlarged scale,
taken along plane 5-5 in FIGURE 1,
FIGURE 6 is a sectional view, on an enlarged scale,
taken along plane 6-6 in FIGURE 1;
FIGURE 7 is a plan view of a further embodiment of
a disposable diaper of this invention with a portion broken
away to show interior detail,
FIGURE 8 is a sectional view, on an enlarged scale,
. .
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,
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ta~en along plane 8-~ in FT5URE 7;
~ I~UR~ n v~w o~ ye~ an~ mb~im~n~ o~ a
disposable diaper of this invention with a portion broken away
to show interior detail;
FIGURE 10 is a plan view of a still further embodiment
of a disposable diaper of this invention with a portion broken
away to show interior detail;
FIG~RE 11 is a plan view of an additional embodiment
of a disposable diaper of this invention with a portion broken
away to show interior detail;
FIGURE 12 is a plan view of still another embodiment
of a disposable diaper of this invention with a portion broken
aw_y lo show interior detail; and
FIGURE 13 is an exploded perspective view showing
re'-ti~e positioning of diaper elements during manufacture of the
dia_~r illustrated in FIGURE 12.
Descrlption of the Preferred Embodiments
For a disposable diaper cf the present invention the
cor -ringent means is a readily stretchable, elastic, preferably
therr-0?12stic member of substantial width that possesses a
cerrain minimum elastic recovery.
The term "elastic," as used herein, refers to sheets,
films, ribbons 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 with the following formula:
Percent retractiOn = Le - Lt X 100
Lë - Lo
where
Lo = orlginal length of sample
Le = fully extended ler.gth
Lt = length of sample measured 3 seconds after
released from extended length.
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. , . _ . . , _ ... , . _ ..
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The thickness of the elastic member generally is 10
s or less, and preferably about 0.5 to about 5 mils. The
elastic member has a recovery at 50 percent elongation after
3 seconds and preferably instantaneously of at least about 90
percent, and preferably close to 100 percent. For ease of stretch-
ability, the modulus of elasticity of the elastic member at 50
?ercent elongation should not exceed about 2000 pounds per square
inch. The modulus of elasticity is preferably substantially less
than 2000 pounas per square inch, and most preferably is
0 about 20 to about 200 pounds per square inch.
It is important that the elastic members in the longitu-
dinal side margins of the diaper not only shorten, e.g., gather,
the side margins but also act on the adjacent sides of the absorbent
batt to create pillow-like bulges or convolutions that shape
_he assorbent batt in the perineal region of the infant for comfort
and casketing, but without incurring a penalty with respect to
absor~ent capacity. Th~ elastic members can act directly on the sides
of the absorbent batt when in physical contact therewith, or can act
hroush the backing and/or the facing. In any event, the recovery
~C Lorce or an extended el~stic member must be sufficient to overcome
the ~:esistance to deformation offered by the relatively stiff absor-
bent batt. And, the relationship between the elastic members and
the batt is such that while the elastic members are effective to
bulge the sides of the batt, the central region of the batt
is not compacted or gathered which would result in the presence
of too much bulky material between the legs of the infant and
detract from the fit of the diaper. Preferably, the elastic
member extends laterally substantially across the entire width
of the diaper side margin; however, in instances where the
~30 ~ensile modulus of the elastic member is relatively high, the
elastic member can be spaced from the absorbent batt.
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:
:
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Any gathering of t~e diaper side marsins that tal:es
place because of the rela~ation of elastic bands present in
the diaper side margins necessarily increases the thickness
dimension of the margins, thereby making effective gasketing
; difficult, and usually requires an excessive compressive force
on the baby's thighs. The diaper construction of the present
invention, on the other hand, by providing relatively wide
but thin elastic members in the dia?er side margins provides
effective gathering not only of the slde margins but also lon-
gitudinal constringement of the adjacent batt side margins
without an attendant undesirable increase in side margin thickness.
In the preferred embodiment of the present invention
the constringent means have a width of at least about 1/4",
preferably a width or at least 1/2", and more preferably a wid~h
of from about 3/4" to about 1 1/4". The width-to-thickness
ratio should be at least about 100 and preferably about 500
to about 1000.
~ eferring to FIGURE 1, disposable diaper 10 embodying
i~ the p:-esent invention is provided with marginal longitudinal
',! 20 cons~-ingent means in opposite side margins 11 and 12 adapted
to provide enhanced fit and gasketing about the baby's thighs.
Additionally, optional transverse constringent means are pro-
vided in end margins 13 and 14 for enhanced fit about the baby's
i waist. The constringent means in each of the side margins is
-.l a relatively wide but thin elastic member, such as elastic mem-
. . .
ber 15 in side margin 11. The optional transverse corstringent
"j
means in the end margins of diaper 10 can be a similar elastic
member such as member 16 in end margin 14. Diaper 10 additionally
:` includes first outer layer or backing 17 made of a moisture-im?er-
vioos web, a generally rectansu1ar absorbent batt'18 posit}oned
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.,:,
11531S2
r. superposed relationship with respect to the bac~ing, and second
outer layer or facing 13 made of a moisture-pervious web ~nd posi-
tioned in superposed relationship with respect to absorbent batt
18. For securement about a baby, diaper 10 is provided with
pressure-sensitive adhesive tape tabs 20 and 21. The longitu-
dinal constringent means are generally parallel to the longitu-
dinal side margins of batt 18, and when the constringent means
are in a relaxed state, diaper 10 assumes a boat-like configura-
tion as shown in FIGURE 1, with side margins 11 and 12 having a
reduced length. As will be discussed in greater detail hereinbelow,
the constringent means also act on the respective adjacent side
margins of absorbent batt 18 and longitudinally constringe the
sid~ r.arsins of batt 18 creating pillow-like marginal bulges or
convo'utions therein.
The individual components of disposable diaper 10
are illustrated in FIGU~E 2. Absorbent batt 18 is superposed
; over backing 17 and is secured thereto by a series of glue lines
23 ce?osited on backing 17. Absorbent batt 18 is of smaller
area than backing 17 and, when substantially centered on backir.g
17, s spacec from longitudinal sides 24 and 25 as well as
transverse sides or ends 26 and 27 and thereby defines the side
and end margins of diaper 10. Absorbent batt 18 is flanked on
all four sides thereof by elastic film members 15, 16, 21 and
22 which, in an extended state r are secured to backing 17 by
means of an elastic adhesive, sonic sealing, or in any other
convenient manner. Moisture-pervious facing 19 is superposed
over absorbent batt 18, is larger in area than batt 18, and is
secured to bac~ing 17, usually by means of the exposed end por-
tions of glue lines 23. However, o~her securement means can be
utilized, if desired. Facing 19 is also secured to elastic
.
_9_
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, .
film members 15, 16, 21 and 22 in a manner similar to the
securement thereof to backing 17.
Batt 18 preferably is provided with a densified skin
in accordance with the teachings of commonly assigned U.S.
Patent No. 3,938,522 to Repke. Glue lines 23 penetrate the
densified skin and cooperate with it to stiffen the mid-portion
of the batt and prevent the central portion of the diaper from
buckling or gathering under the influence of the constringent
means hereinafter described.
The action of a relaxed constringent means on the rest
of diaper components is illustrated in FIGURES 5 and 6. The
direct action of elastic member 15 on facing 19 and backing 17
secured thereto gathers the resulting laminar composite forming
a plurality of gathers or macropleats (FIGURE 5) in side margin
11. At the same time elastic member 15 acts on the adjacent
side margin of absorbent batt 18 to produce controlled pillow-
like convolutions or bulges (FIGURE 6) at the sides thereof.
Because of the aforementioned cooperative action of the
densified skin and the glue lines, the central portion of the
0 batt, and the central portion of the other diaper components,
~ are not influenced by the constringent means, and hence remain
; ungathered. Thus~ in accordance with the present invention
.,~
there is a transition from gathers at opposite side margins
of the diaper, to bulges inwardly of the side margins and
generally in alignment with opposite sides of the batt, and
finally to a relatively smooth and undisturbed diaper mid-
` portion. The generally smooth mid-portion of the batt occupies
at least 20 percent of the batt width dimension and preferably
from akout 50 percent to about 80 percent. The bulges in the
side margins of the batt have a
, --10--
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, ~ ..
115~
~ ximum height di~er.sion at the sides of the batt, and taper
generally uni~ormly inwardl~ to ~h~ g~ndr~lly ~oo~h b~ mld-
portion.
The configuration that disposable diaper 10 assumes
when applied to a baby is illustrated in FIGURE 3. Partially-
extended diaper side m2rgins 11 and 12 provide a co~fortable yet
positive seal about the baby's thighs that readily accommodates
leg movements of the baby, while optional elastic members in
diaper end margins 13 and 14 assure good fit about the baby's
waist.
FIG~RE 4 shows disposable diaper 30 that is simil2r
to disposable diaper 10 but lacXs the optional elastic member
in diaper end margin 33. In the embodiment exemplified by
FIG~RE 4 the elastic member in diaper end margin 34 is similar
to elastic member 16 in FIGURE 1 and performs in the same man-
ner. The construction of diaper side margins 31 anc 32 is
substantially the same as in diaper side margins 11 and 12.
Another embodiment within the purview of the present
invention is illustrated in FIGURES 7 and 8. In dlsposable
diaper 40~ elongated thin elastic ribbons 43 and 44 are secured
to diaper backing 47 and diaper facing 49 so that a portion of
each of ribbons 43 and 44 underlies substantially rectangular
absorbent batt 48 and provides direct constringent action on
the side margins of batt 48 when rela~ed to reduce the length
of diaper side margins 41 and 42. If necessary, side margins
of absorbent batt 48 can be secured, by means of an adhesive
or in any other convenient manner, to respective underlving
portions of elastic ribbons 43 and 44; however, ususally i'
is not necessary to do so inasmuch as the coefficient of friction
~0 between the resulting contiauous surfaces is sufficient to
115~15Z
~ransmit a constringing force ~rom elastic ribbons 43 and 44 to
batt 48. Usually absorbent batt 48 overlies less than about
one-half o~ the width of elastic ribbons 43 and ~. Central
glue lines 45 provide attachment means for absorbent batt 48
and facing 49 to backing 47. Outer glue lines 57 and 58 provide
further securement of respective elastic ribbons 43 and 44 to
backing 47. Adhesive tape tabs 46 and 50 provide diaper secure-
ment means when diaper 40 is applied about a baby.
In the embodiment illustrated by FIGURE 9, disposable
diaper 60 is provided with absorbent batt 68 having curvilinear
side cut-outs 71 and 72 and sandwiched between facing 69 and
backing 67. Glue lines 65 serve to secure batt 68 and facing
; 69 to bac.1{ing 67. Relatively wide elastic ribbons 63 and 64
are situated in generally rectilinear diaper side margins 62
and 61, respectively, so that an innermost central portion of
each of elastic ribbons 63 and 64 underlies adjacent side mar-
gins of absorbent batt 68. Elastic ribbons 63 and 64 extend
substantially the entire length-of diaper side marsins 62 ar.d
61, -es~ectively, and are intermittently secured both to backing
,,
2C 67 and facing 69 so ~s to provide the desired gathering. In
addition, paired outer glue lines 77 and 78 provide further
securement of elastic ribbons 63 and 64 to bac'~ing 67. Prolrud-
ing ears 73, 74, 7; and 76 of absorbent batt 68 overlap substan-
tially the entire width of the respective elastic ribbons 63
~j and 64 and provide additional absorbent capacity which can be
readily utilized by building into absorbent batt 68 appropriate
capillary transport means. Adnesive tape tab means 66 and 70
provide means for securing diaper 60 about a baby.
In the embodiment of FIGURE 10, disposable diaper 80
is provided with substantially rectangular absorbent batt or
.
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r.el 88 having generally rectilinear sides, sandwiched be~weer.
bac~ing 87 and ~acing ~9, and ~ogether with backi~g a7 and f~cing
89 defining diaper side margins 81 and 82. Curvilinear cut-outs
97 and 98 are provided in the respective central portions of
margins 81 and 82 for further fit enhancemRnt. Pre-stretched
elastic film ribbons 83 and 84 are positioned in respective mar-
gins 82 and 81 and are secured to backing 87 and facing 89 along
the longitudinal sides of absorbent panel 88. Glue lines 85
secure facing 89 and absorbent panel 88 to backing 87, and ad-
hesive tape tabs 86 and 90 provide diaper securement means.
Yet another embodiment of a disposable diaper accord-
ing to the present invention is shown in FIGURE 11 where dispos-
able diaper 100 is provided with shaped absorbent panel 108
~aving curvilinear cut-outs 111 and 112 and centrally ju~taposed
between backing 107 and facing 109. Both panel 108 and facing
109 are secured to backing 107 by a plurality of lonsitudinally
extendins glue lines 105. Curvilinear cut-outs 117 and 118,
similar ln configuration but of smaller size than cut-outs 111
and 112, are provided in the side portions of facing 109 and
'` 20 ba_ki~.g 107 that form aiaper side margins 101 and 102, respec-
tively, so that margin cut-out 117 subtends panel cut-out 111
and margin cut-out 118 subtends panel cut-out 112. Elastic film
member 103 is positioned in diaper margin 102 between protruding
ears 113 and 114 of absorbent panel 108 and is intermittently
secured to facing 109 and backing 107 in a pre-stretched state
at an elongation of at least about S0 percent and preferably
. about 100 percent. In a similar manner, elastic film member 104
is positioned in diaper margin 101 between protruding ears 11;
~ and 116 of absorbent panel 108 and is secured to facing 109 and
r;l 30 backing 107. Diaper securement means are provided by adhesive
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115~15~
~pe tabs 105 and 110.
Referring now to FIGU~S 12 and 13, a still ~urther
embodiment of the invention is illustrated in its entirety at
120, and includes a first outer layer 121 in the form of a
moisture pervious facing, a second outer layer 122 in the form
of a moisture impervious backing, and a third layer 123 in the
form of an absorbent batt sandwiched therebetween. Outer layers
121 and 122 have the same outer dimensions and are coterminous
with one another. Batt 123 has an external configuration similar
to layers 121 and 122, and is smaller than and centered relative
to layers 121 and 122. Parallel glue lines 124 on backing 122
secure the batt to the backing, and the outermost glue lines
(and the ends of the intermediate glue lines) secure the portions
of layers 121 and 122 that extend beyond batt 123 to one another.
The end portions 125 and 126 of batt 123 are generally
equal in width and are wider than the batt mid-portion 127.
For improved fit, the narrowest part 128 of the batt mid-portion
is offset toward batt end portion 126, the portion that is
adapted to be placed in front of the infant. Batt portion 128
is G.-. relatively short length and is formed between parallel
side edges 128a and 128b. Batt side edges 129, 130, 131 and
1 132 flare outwardly from the ends of edges 128a and 128b and
terminate in end portion 129a parallel with end portion 131a
and end portion 130a parallel with end portion 132a. In a
most preferred embodiment of the invention, edges 129 and 131
are disposed at an angle of 25 and edges 130 and 132 are dis-
posed at an angle of 35, so that the included angle between
edges 129 and 130 and edges 131 and 132 is 120.
As with the previously described embodiments, diaper
120 includes constringent means 134 and 135 at opposite sides
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llS~l.S2
~ the diaper, ar.~ optional constringent means 136 and 137 at
opposite ends of the diaper. The iilustrated constringent means
are in the form of elongated elas~ic members that are secured
in a stretched condition to layers 121 and/or 122. The
securement means may take the form of one or more spaced rows
138 of spaced securement zones. The elastic members which form
the constringent means 134 and 135 are parallel with the side
edges of the batt between the overlapping side edges of layers
121 and 122 for improved application of constringing forces to
not only the side margins of the facing and backing layers, but
also the sides of the panel 123. The elastic members extend
beyond the ends of the panel 123, and completely from end to end
of the diaper.
As with the previously described embodiments, tape
tabs 1~0 are provided for securement of the diaper about an
infant.
Elastic film members suitable as constringing elements
for the diapers contemplated herein can be extruded to the desired
thickness utllizing unvulcanized, thermoplastic comDositions which
are m,ade up OL an elastomeric component and an optional compatible
modifier which is a thermoplastic poIymer o. a relatively low
molecular weight but solid at ambient temperature.
Illustrative of the elastomeric components suitable for
present purposes are block copolymers which comprise terminal
thermoplastic polymer biocks and at least one non-terminal or
intermediate elastomeric polymer block. Block copolymers of
this general type may be prepared using a step-wlse polymeriza-
tion initiator, e.g., an organolithium compound. Such block
polymerization techniques are well known in the art.
The elastomeric component can be linear or radial
A~-B-A2 block copolymers or mixtures thereof with simple ~l-B
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~LS~lSZ
lock copolymers whe-e Al and A2 can be ali.`~e or different and
represent a thermoplastic polymer block, such as poly~vinyl
arene) block, and B represents an elastomeric polymer block
such as a conjugated diene or a lower (i.e., Cl-C4) alkene. The
modifier component is a low molecular weight thermoplastic poly-
mer havins an average molecular weight of about ~00 to about
7,500 and is present in the composition in an amount of about
zero to about 200 parts by weight per 100 parts by weight of
the elastomeric component.
A preferred thermoplastic film composition for the
elastic film members comprises an elastomeric component which
contains, as a major constituent thereof, an unvulcanized linear
block copolymer of the general configuration
Al -B - A2
wherein A~ and B have tne same meaning as hereinabove. In
these block copolymers the A-blocks are dérived from styrene or
styrene homologues, and the B-blocks are derived from conjugated
dienes or lower alkenes. The thermoplastic polymer modifier is
compa~ible witn the elastomeric component and associates prin-
cipally wit~. the the moplastic terminal blocks of the aforesaid
unvulcanized block copolymer. The thermoplastic polymer modifler
prererably has an average molecular weight of about 1000 to about
3000, and is present in the film composition in an amount of
about 80 to about 200 parts by weight per 100 parts by weight of
the elastomeric component.
The preferred Al-B-A2 block copolymers have A-blocks
derived, i.e., polymerized or copolymerized, from styrene o
styrene homologues; and B-blocks derived from conjugated dienes,
such as isoprene or butadiene, or from lower alkenes, such as
ethylene and butylene. Small proportions of other monomers
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. _
~15~1~2
lso may enter into the block copolymers themselves. The in-
dividual A-blocks can have an average molecular weight o~ at
least about 6000, preferably in the ranse of about 8000-30,000,
and the A-blocks constitute about 5-50 percent, preferably about
10-30 percent, by weight of the block copolymer. The average
molecular weight of the B-blocks for linear Al-B-A2 block copoly-
mers 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 7;,000-200,000. The average molecular weight of the radial
Al-~-A2 block copolymers preferably is in the range of about
125,000-400,000. The term "linear block copolymer" (or copoly-
mers) includes branched Al-B-A2 copolymers as well as unbranched
A1-~-~2 copolymers.
The radial ~1-B-A2 copolymers useful for manufacture
of e astic ~embers for diapers of this invention are of the
type described in United States Letters Patent No. 3,281,383 to
Zelinski et al. and conform to the foll~ing general formula:
(A-E-)nX, wherein A is a thermoplastic block polymerized from
styrene or styrene homologues, B is an elastomeric block derived
from conjugated dienes or lower alkenes, as indicated above, X
is an organic or inorganic connecting molecule, with a function-
ali.y 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 11, 1975 issue of Chemical Week. As used hereinabove,
"n" has a value corresponding to the functionality of X.
The preferred elastic film member is highly thermo-
plastic and, though elastomeric, is unlike rubber in that the
film exhibits a relatively sharp melting point and is capable
of being heat shaped. Also, the elastic film member can form
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~15~15Z
-~ermanert heat seals to substrates such as non-woven fabrics,
or the like, at relatively low heat sealing peak temperatures,
generally not above about 3;0F. 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 least 75 percent, preferably at least
about 80 percent, and a 50 percent rubber modulus of not a~ove
about 2000 pounds per square inch, preferably in the range of a~out
20 to about 200 pourds per square inch at S0 percent elongation. The film
member also is flexible, extensible and soft and normally
exhibits a Gurley stiffness of about one or less at a film
thi^~ness of one mil, and an elongation to break of at least
about 300 percent, preferably at least about 400 percent, in
at least one directlon at ambient temperatures.
While the constringent means described above is in
the fcrm of a single elastic ribbon at opposite sides of the diaper,
the present invention is not limited thereto, and it is contem~
plared that other forms of constringent means may be provided,
so long as the constringent means is effective to bulge the
side margins of the batt. In this regard, it is contemplated
that each side margin of the diaper may include a plurality of
spaced, parallel longitudinally extending elastic members;
such as, bands, round or flattened tubes, monofilaments, etc.
By way of example, and with reference to ~IGURE 1,
the illustrated ribbons 15 and 21 may be replaced by a pair of
1/4" wide elastic bands that are parallel with one another and
with the adjacent side edge of the batt. With such an arrange-
ment, the innermost elastic bands would be disposed directly
adjacent to the side edge of the batt, and the center lines
3b of the bands would be spaced from one another by 3/~". It will
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~15~152
e recognized that such a constringent means is less costly
~h~n ~ construc~ion that us~s a 1" wlde elastic m~mber, b~c~use
less material is utilized. Nevertheless, it is possible to
effect the desired gathering at the sides of the diaper, and
bulging of the side margins of the batt, without undue stress
concentration upon an infants skin, since the pulling force of
the plural elastic members is distributed over a relatively
large area. Stated differently, the desired results of the
invention can be achieved by the use of plural elastic members
at each side of the diaper, since the pulling force required for
each elastic member is less than that required for a single
elastic member and the amount of pre-stretch for the individual
plural elastic members can be reduced accordingly. With such
an a~rangement it is also possible to pre-stretch the elastic
members a different amount, if desired or necessary, to
achieve the desired panel bulging effect.
Several different types of facing materials may be
used f~r diaper facing. For example, the facing may be a non-
woven web made up of a mixture of fibers consisting predominantly
of ine~:pensive short cellulosic fibers such as wood pulp fibers
or co_ton linters, in amounts of about 75% to about 98%, the
balance being textile length fibers such as rayon as described
in U.S. Patent No. 3,633,348 to Liloia et al.
Non-woven facing materials suitable for use in dispos-
able diapers of this invention can have fabric weights in the
range of about .5 to 5 oz./yd.2 and densities of less than 0.15
g./cc., generally in the range of about 0.0; to about 0.1 g./cc.
The dry strength of the facing sheet for a fabric having a
weight of about 1.5 oz./yd.2 is at least 0.15 lbs./in. of width
in the machine direction and at least 0.1 lbs./in. of width in
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. ;
~lS~l~Z
the cross direction. Such fabrics have unusually good elonga-
an, loft, softness, and drape characteristics.
~ acings may also be made of an apertured, non-~Joven
fabric which is formed, for example, in accordance with the
teachings of commonly assigned U.S. Patent Nos. 2,862,251; 3,0~1,514
and 3,081,515~ Briefly, suc~ fabrics are foraminous structures
wherein groups or groupings of fibers have been rearranged from
a fibrous non-woven starting web into positions surrounding less
dense fabric portions by passage of a fluid through the starting
material. ~he fibers within the aroupings are mechanically inter-
locked, and mav be arranged into various patterns, as is well known
by those skilled in the art. A suitable binder may be utilized to
help retain the fibers in their rearranged locations, as is also
well known by those skilled in the art. The fabric can be made of
naturally occuring fibers, synthetic fibers, or blends thereof.
Typical facing sheets made of a fibrous polyester type material
can have a weight of about 0.75 oz./yd.2.
The facing may be the same size as, and coterminous with,
the backing; or alternatively, the facing may be wider than the bac'c-
ing and have its side edges inwardly folded so that the facing is
_otermlnous with the backing, as is shown in Figure 3 of U.S. Patent
.~lo. 3,612,055. In the latter case, the elastic members may be
secured above the inwardly folded side edges of the facing.
In addition, facings can be formed of a non-apertured
material, such as a non-woven isotropic web or of an apertured poly-
olefin or polyester film having the desired moisture permeability.
In all of the aforementioned facings the material should be rela~ively
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 backing, can be formed in accordance
with the teachings of U.S. Patent No. 3,612,055 to Mesek et al.
A suitable backing material for the diapers embodying
the present invention can be an opaque polyolefin, e.g., poly-
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115;~52ethylene, web about 0.001 inch thick. Another suitable materiai
for this purpose is a polyethylene terepthalate web having a
thickness of about 0.0005 inch.
In use, the disposable diaper is applied to the baby
by laying out the diaper on a suitable flat surface and placing
the baby thereon so that the waist-underlying end of the diaper
is that having the fastener means. The other end of the diaper
then extends downwardly between the infant's legs. Next, the
downwardly extending end of the diaper is brought up between
the baby's legs to a position covering the perineum and con-
tiguous with the front portion of the baby's waist. The diaper
is thereafter secured to the baby by placing the corners of the
waist portion of the abdomen-covering end as far around the
baby's waist as they will go and by bringing the corners of the
underlying end of the diaper into an overlapping relationship
with the aforementiGned corners so that the diaper snugly en-
circles the baby's waist and provides a custom fit. The adhe-
sive tab fasteners are then prepared for use and the diaper is
secured in the desired position by simply urging the pressure-
sensitive adhesive surface of the tape tab in contact with theadjacent outer surface of the opposite corner of the diaper.
The applied diaper assumes a configuration such as shown in
FIGU~E 3.
The foregoing description and the drawings are illus-
trative and are not to be taken as limiting. Still other varia-
tions and modifications are possible without depar~ing from the
spirit and scope of the present invention.
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