Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
DISPOSABLE DIAPERS ~ ~ 7
BACKGROUND OF THE INVENTION
This invention generally related to a disposable
diaper and, more particularly, to fastening means used to
releasably bond together laterally opposite side portions
of front and rear bodies of such a diaper at the level of
waist zone.
SUMMARY OF THE INVENTION
According to a broad aspect of the present
invention, there is provided a disposable diaper with
fastening means for fastening together laterally opposite
side portions of front and read waist sections of the
diaper as fitted to an infant. Each of the fastening
means includes a fastening tape and a release tape. The
fastening tape has an inner adhesive surface, an outer
nonadhesive surface, oppositely spaced-apart front and
base ends, and a nonadhesive pick-up lobe formed at the
front end. The nonadhesive pick-up lobe comprises the
front end of the fastening tape folded back on itself
with the inner adhesive surface within the fold, and an
outer surface of the lobe comprises the outer nonadhesive
surface of the fastening tape. The base end of the
fastening tape is fixedly bonded to a backsheet defining
an outside surface of the diaper. The release tape has a
front end and is fixedly bonded to a topsheet defining an
inside surface of the diaper. The fastening tape is
releasably bondable by the inner adhesive surface to the
release tape and is constructed and dimensioned such that
in the bonded condition, the nonadhesive pick-up lobe
partially extends across the front end of the release
tape to a position beyond the front end, so that when the
fastening tape is bonded to the release tape under
pressure, the nonadhesive pick-up lobe acts to press the
front end into positive engagement with the topsheet.
The bond strength between the inner adhesive surface and
the release tape is less than 150g.
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The important feature of the invention such that
said nonadhesive pick-up lobe of the fastening tape
projects forward beyond said front end of the release
tape, in other words, said front end underlies the lower
surface of said nonadhesive pick-up lobe in contact
therewith allows said front end to be bonded to the
diaper at predetermined location with reliability at
least equal to that for the remaining portion of said
release tape by pressing down the composite tape
comprising the fastening tape laid upon the release tape
from the top side of said fastening tape toward the
diaper.
When said fastening tape's nonadhesive pick-up
lobe is separated from said release tape's release
surface on which said adhesive surface has temporarily
been bonded with said nonadhesive pick-up lobe pinched by
fingers, said front end as well as the remaining portion
of said release tape is never peeled off from the top
surface (i.e., inner surface) of the diaper on which the
release tape should be permanently bonded, no mater how
quickly or even momentarily said fastening tape is pulled
off from said release tape, not only because said
fastening tape's adhesive surface is not bonded to said
release tape's front end but also because the bond
strength(or
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temporary bonding) between said adhesive surface and said
release surface is adjusted to be less than a
predetermined value.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described more in details by
way of example in reference with the accompanying
drawings, in which:
Fig l is a plan view showing the inside of a diaper
as partially broken away;
Fig. 2 is an enlarged sectional view taken along a
line X-X in Fig. l; and
Fig. 3 is a sectional view of conventional fastening
means.
DESCRIPTION OF THE PRIOR ART
As will be apparent from Fig. 3 of the accompanying
drawings, known fastening means are adapted to be
attached to laterally opposite side portions 5 of a rear
body at the level of waist zone, respectively, each
comprising fastening tape 3 having an adhesive surface l
defined by its inner surface and a nonadhesive pick-up
lobe 2 formed at its front end, on one hand, and a
release tape 4 upon which the adhesive surface l is laid
and temporarily bonded, on the other hand. The fastening
tape 3 is constructed and dimensioned so that the
nonadhesive pick-up lobe 2 comes in a retracted position
with respect to a front end 7 of the release tape 4
having an adhesive surface 6 attached to each of said
opposite side portions 5 on the top surface thereof,
namely, the front end 7 of the release tape 4 projects
forward beyond the front end of the nonadhesive pick-up
lobe 2 when the fastening tape 3 has been laid upon the
release tape 4. Such arrangement intends to facilitate
the fastening tape 3 to be easily separated from the
release tape 4 with the nonadhesive pick-up lobe 2
pinched by fingers.
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However, when such composite tape comprising the
fastening tape 3 having its adhesive surface 1 laid upon
the release surface (i.e., top surface) on the release
tape 4 is attached, on the production line of diaper, to
the diaper at each of the waist zone's laterally opposite
side portions 5 by downwardly pressing the composite tape
laid upon the diaper at said portion utilizing suitable
press means with a smooth press surface, a difference in
level will be created between the front end 7 and the
nonadhesive pick-lobe 2 if the design is adopted such
that the front end 7 of the release tape projects beyond
the nonadhesive pick-up lobe 2 of the fastening tape 3.
Such difference in level leads to inadequate pressure
exerted on the front end 7 and, in consequence, the front
end 7 is often unreliably attached to the diaper at each
of the waist zone's laterally opposite side portions 5.
One of the measures to solve such problem is to use the
press means having a press surface stepwise configured in
conformity with said difference in level. Even if such
press means is used, however, the stepwise portion of
said press surface is often misaligned with the stepped
portion of the counterpart for several reasons, for
example because said composite tape has a considerable
flexibility and because the production line of diaper is
required to handle the components of diaper including
this composite tape at high speed in order to achieve
mass production at a cost as low as possible.
Accordingly, it is difficult for unique configuration of
the press surface alone to solve the problem.
As has previously been described, if the front end 7
of the release tape 4 is unreliably attached to the
diaper, said front end 7 will be peeled off or lifter out
from the diaper due to movement of the diaper or rubbing
contact between said front end 7 and wearer's skin,
sometimes resulting in troubles such as eruption and
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scratch of wearer's skin. This will be a serious problem
when the wearer is a newborn.
In view of the problem as has been mentioned above,
it is a principal object of the invention to modify a
relative position of the fastening tape's nonadhesive
pick-up lobe and the release tape's front end and thereby
to solve the problem.
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PREFERRED EMBODIMENTS OF THE INVENTION
Referring of Fig. 1, a known disposable diaper 12 is
illustrated, of which the rear body is provided at its
waist zone's laterally opposite side portions with
fastening means 10, respectively. This diaper 12 comprises
a liquid-permeable topsheet 13, a liquid-impermeable
backsheet 14, a liquid-absorbent panel 15 sandwiched
between said sheets 13, 14, and elastic members 16a, 16b
provided around the leg-openings and the waist-opening,
respectively. It is well known by those skilled in the art
that the fastening means 10 are provided to connect the
laterally opposite side portions of the rear body having
said means 10 attached thereto with the corresponding side
portions of the front body.
Referring to Fig. 2, each of the fastening means 10
comprises a piece of fastening tape 20 and a piece of
release tape 21 (referred to hereinafter simply as
fastening tape and release tape, respectively). The
fastening tape 20 having a base end 24 is applied on its
inner surface with pressure sensitive adhesive to define an
adhesive surface 22 and folded back at its front end to
define a nonadhesive pick-up lobe 23. The release tape 21
is also applied on its inner surface with adhesive that is
equally effective to the adhesive applied on the fastening
tape 20 so as to define an adhesive surface 25. The
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release tape 21 is fixedly bonded with its adhesive surface
25 onto the top surface (i.e., inner surface) of the
topsheet 13 at each of the waist zone's laterally opposite
side portions 11. The fastening tape 20 is fixedly bonded
at their base ends 24 onto the back surface (i.e., outer
surface) at each of the waist zone's laterally opposite
side portions 11. Each fastening tape 20 is folded over
its main portion 26 including the nonadhesive pick-up lobe
23 onto the associated release tape 21 so that the adhesive
surface 22 may be laid upon and temporarily bonded to a
release surface of the release tape 21 defined by the top
surface thereof. Length of said main portion 26 is
dimensioned so that, in this state, the nonadhesive pick-up
lobe 23 partially projects beyond the front end 27 of the
release tape 21, i.e., said front end 27 lies between front
and base ends 28, 29 of the nonadhesive pick-up lobe 23.
If the front end 28 of the nonadhesive pick-up lobe 23
is positioned to be aligned with the front end 27 of the
release tape 21, it will be difficult to pinch the
nonadhesive pick-up lobe 23 by fingers. If the front end
27 of the release tape 21 is positioned in alignment with
or outside (i.e., to the right of) the base end 29 of the
nonadhesive pick-up lobe 23, not only it will be difficult
to pinch the nonadhesive pick-up lobe 23 by fingers but
also the adhesive surface 22 may contact the front end 27
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of the release tape 21, thereby making it difficult to
separate the fastening tape 20 from the release tape 21 and
furthermore it is apprehended that, depending on bonding
strength (or separation-resistance) between the adhesive
surface 22 of the fastening tape 20 and the release surface
of the release tape 21 (i.e., temporarily bonded surfaces),
the front end 27 of the release tape 21 may be peeled, torn
off and lifted out from the topsheet 13 as the fastening
tape 20 is pulled to separate it off from the release tape
21.
Said bond strength is preferably less than 150 g. To
measure this bond strength, the nonadhesive pick-up lobe 23
is held by a tester's chuck and pulled (clockwise as viewed
in Fig. 2) so as to separate the adhesive surface 22 of the
fastening tape 20 extending over its main portion 26 off
from the release tape 21. The bond strength corresponds to
a value of the minimum force (g) required to separate said
surface 22 off from the release tape 21. So far as this
value is less than 150 g, there is no possibility that the
front end 27 as well as the other portion of the release
tape 21 may be peeled, torn off and lifted out from the top
surface of the waist zone's laterally opposite side
portions even if the fastening tape 20 is quickly or even
momentarily pulled so as to be separated from the release
tape 21.
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As has previously been mentloned, the fastening tape
20 and the release tape 21 as illustrated in Fig. 2 are
introduced onto the diaper production line where the
composite (laminated) tape is laid on the top- and
backsheets 13, 14 which are other components of the diaper
and then attached thereto by pressing all these components
together utilizing suitable press means. In this case, the
front end 27 of the release tape 21 is most hardly pressed,
since portions of the tapes 20, 21 overlying the front end
27 of the release tape 21 have a total thickness
substantially larger than a total thickness of the
remaining portions. Consequently, the front end 27 is
firmly bonded to the topsheet 13 of the dlaper at the waist
zone's laterally opposite side portions 11.
Materials for the fastening tape 20, the release tape
21 and the adhesive agent for the adhesive surfaces 22, 25
may be selected from those usually employed by the diaper
industry. For example, the fastening tape 20 may be made
from paper of high quality or laminate sheet consisting of
nonwoven fabric and plastic film. The release tape 21 may
be made from paper of high quality having its top surface
(i.e., release surface) coated with silicone resin.
Adhesive agent for the adhesive surfaces 22, 25 may be of
so-called hot melt type. Materials for the topsheet 13,
the backsheet 14 and the panel 15 may be also selected from
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those conventlonally used in this industry. For example,
the topsheet 13 may be made of nonwoven fabric or porous
plastic film. The backsheet 14 may be made of plastic film
or laminate consisting of such film and nonwoven fabric.
The panel 15 may be made of fluffy or crushed pulp mixed
with high absorption polymer powder.
Construction and operation of the fastening tape
incorporated in the diaper of the invention make it
possible to avoid the problems, for example, eruption,
scratch or the like of wearer's skin that will be caused
particularly if the front end of the release tape is peeled
torn off and lifted out from the topsheet. Accordingly,
the diaper of this invention can be used also for newborn
babies without any anxiety.
The nonadhesive pick-up lobe projects forward beyond
the front end of release tape, defining a gap between this
lobe and the topsheet of diaper, and thereby allows said
lobe to be very easily pinched by fingers.
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