Note: Descriptions are shown in the official language in which they were submitted.
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Adhesive-Free Female Fastening Portion
for a Mechanical Fastening Device
Field of the invention
The present invention relates to an adhesive-free female fastening portion
for a refastenable mechanical fastening device. Its application is intended
for use on disposable absorbent articles.
Background of the invention
Disposable absorbent articles, in particular, disposable diapers are well-
known articles of manufacture that are designed to be wom principally by
infants and incontinence sufferers. Such diapers are worn about the
2 0 lower torso of the wearer and are intended to absorb and contain urine
and other bodily discharges, thus preventing the soiling, wetting, or similar
contamination of articles (for example, clothing, bedding, other persons,
etc.) that may come into contact with :;uch a diaper in use.
2 S When using a disposable diaper, the diaper user fits the diaper on
the wearer and fastens it about the waist of the wearer with the aid of a
fastening device to effect a side closure. Fitting the diaper about the
wearer usually requires the front and the back waist portions of the diaper
to overlap each other. Since proper and sustained fit about the waist and
3 0 legs of the wearer is vital for optimal performance in terms of minimising
the leakage of body exudates out of the diaper, a diaper fastening device
must be capable of providing an effective side closure in which the front
and back waist portions are maintained in an overlapping configuration.
As the diaper is worn, the overlapping portions are subjected to forces that
3 5 tend to cause the portions to shift position relative to each other.
Unless
such shifting is limited, the fit and containment characteristics of the
diaper
deteriorate as the diaper is worn. l'hus, the fastening device must be
designed to securely engage so it does not separate due to the peel
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forces and shear stresses encountered by the fastening device during
use.
The use of fastening devices for securing the front and back
portions on a disposable absorbent article is widely known. Examples of
adhesive tape tab fastening devices are disclosed in US RE 26,151,
US 3,848, 594, US 4,985,025, EP 0 286 030 and many other prior art
documents. While tape tab fastening devices provide a secure means for
fixing a disposable absorbent article around the waist of the wearer during
1 0 use, they are not completely satisfactory. Such fastening devices are
often only usable upon initial fixation of the disposable absorbent article
and refastenabiiity is not a concomitant benefit. Furthermore, the
fastening devices display an unsatisfactory resistance to contamination
from oils and powders. Thus, the prior art documents disclose many
1 5 alternatives as potential solutions to such deficiencies. For example
mechanical fastening devices have been contemplated and are disclosed
in many publications such as US 3,110,3112, US 4,259,957 and
EP 0 235 014. Such mechanical fastening devices exhibit a reduced
sensitivity to contamination and have the advantage of refastenability. As
2 0 a consequence, these mechanical fastening devices have gained in
popularity over the last few years. These mechanical fastening devices
generally constitute two elements: a female fastening portion comprising
a loop material and a male fastening portion comprising a hook fastening
material.
After establishing the principal benefits of the mechanical fastening
devices over adhesive tape tab fastening systems, it was discovered that
a problem arose in connection with adhesive-based female fastening
portions. Typically, the female fastening portion comprises a textile
3 0 material. It was recognised that the adhesive attachment of the textile
material to a base substrate affected the functional performance of the
loops. Generally, the adhesive tended to bleed through the textile
material structure resulting in the loops sticking to the textile material and
rendering a representative proportion of the loops completely ineffectual
3 5 for engagement with the hook fastening material of the male fastening
portion.
In order to address such a problem, US 5,554,239 focuses on the
use of a lower basis weight in the first zone of the adhesive to prevent
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bleeding from the first zone to the loop material. Nevertheless, the use of
a higher basis weight in the peripheral portions of the loop material in the
second zone of the adhesive resulla in bleeding and consequently,
deadening of the loop material. Therefore, the functional performance of
the loop material for engagement is greatly impaired and in some cases
destroyed.
In contrast, European patent application number 9606398, filed on
23 May 1996, describes a preferred embodiment in which the assembly
1 0 for use as a female fastening portion on a disposable absorbent article
comprises a first layer and a second lakrer, affixed to each other by means
of thermobonding, and loop elements, which are attached to the second
layer. The first layer is dense andl the second layer is formed by
interfacing the yams in a warp or weft pattern. US 5,256,231 describes a
1 5 sheet of loop material that is designed to be cut into pieces to form loop
portions for mechanical fastening devices. The sheet of loop material is
made by forming a sheet of longitudinally oriented polymeric fibres so that
the sheet has arcuate portions projecting in the same direction from
spaced anchor portions, and then by forming at least a portion of a
2 0 backing around the spaced anchor portions by extruding thermoplastic
material onto the anchor portions. The non-woven fibre sheet has a basis
weight in the range of 5 to 300 gramms~s per square metre and preferably
in the range from 15 to i 00 grammes per square metre for applications in
which the fastening device will be opened less than ten times, and in the
2 5 range from 75 to 150 grammes per sq~nare metre for applications in which
the fastening device will be opened more than ten times. In a further
embodiment, yams may be used with a denier ranging from 50 to 300.
As a result of the above prior art attempts, it has been recognised
3 0 by those skilled in the art that it would be desirable to provide a female
fastening portion with an extremely high number of functionally operating
loops. Furthermore, it would be most advantageous to reduce the basis
weight of the textile material from a functional and aesthetic point of view.
The basis weight reduction results in better material utilisation, allows the
3 5 artwork on the substrate underlying they textile material to be more
clearly
highlighted and leads to an improvement in tactile qualities. It is also
known that using current technologies, it is difficult to reduce the basis
weight of the female fastening portion without causing a degradation in
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the performance of the mechanical fastening device, i.e., the shear stress
and peel force values deteriorate.
It has now been discovered that the benefits of the present
invention range from a female fastening portion exhibiting a superior
functional performance when engaged with the hook fastening material of
a mate fastening portion; to a low basis weight assembly, which is most
attractive from a materials' utilisation aspect; to a female fastening portion
with a very satisfactory peel force resistance value when engaged with the
1 0 hook fastening material of the male fastening portion; to a softer and
more
gentle female fastening portion; to a fastening device that is adhesive free;
and to a mechanical fastening device that leads to a high level of user
satisfaction and confidence.
1 5 Summary of the invention
The female fastening portion of the present invention represents a
constituent member of a mechanical fastening device, the other
constituent member being a male fastening portion, which is designed to
mechanically engage with the female fastening portion. In particular,
2 0 hook type male fastening portions engage with loop type female fastening
portions.
In one aspect, the present invention concerns a female fastening
portion for a refastenable mechanical fastening device wherein the female
2 5 fastening portion is capable of engaging a complementary male fastening
portion. The female fastening portion comprises a textile material, which
is disposed adjacent to a substrate. The textile material is non-adhesively
bonded to the substrate and has a basis weight that is not greater than 60
grammes per square metre. More particularly, the textile material of the
3 0 female fastening portion comprises a basis weight not greater than 40
grammes per square metre, preferably not greater than 34 grammes per
square metre and more preferably not greater than 28 grammes per
square metre. The female fastening portion may either be thermobonded
or extrusion bonded to the substrate. In a preferred embodiment of the
3 5 present invention, the textile material has a three bar warp pattern
comprising loops, courses and wales. in another preferred embodiment
of the present invention, the textile material has a two bar warp pattern
comprising only courses and wales.
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In another aspect of the present invention, the female fastening
portion is applied to a disposable absorbent article, such as a diaper. The
substrate, to which the textile material its attached, can comprise either a
film adjacent to the outside surface of the body portion with a layer of
. 5 adhesive interposed between or just ;>imply the outside surface of the
body portion.
Brief description of the drawings
It is believed that the invention will be better understood from the
1 0 foregoing description in conjunction with the accompanying drawings in
which:
Figure 1 is an enlarged sectional view of the female fastening portion
according to the teachings of the present invention;
Figure 2 shows a plan view photograph ~f a three bar warp knitted female
fastening portion;
Figure 3 illustrates the construction of the three bar warp knitted female
2 0 fastening portion as shown in Figure 2; a.nd
Figure 4 details a partially cut-away perspective view of a diaper
embodying the refastenable mechanical fastening device of the present
invention.
Detailed description of the invention
As used herein, the term "textile" inclucles knit material, woven material,
and scrim. As used herein, the term "disposable absorbent article" refers
to articles which absorb and contain body exudates; and more
3 0 specifically, refers to articles which are placed against or in proximity
to
the body of the wearer to absorb anti contain the various exudates
discharged from the body and which are intended to be discarded after a
single use (i.e., they are not intended to be laundered or otherwise
restored or reused) and, preferably, to be recycled, composted or
3 5 otherwise disposed of in an environmentally compatible manner. As used
herein, the term "diaper" refers to a gam~ent generally wom by infants or
incontinence sufferers that is drawn up between the legs and fastened
about the waist of the wearer. It should be understood, however, that the
present invention is also applicable to other disposable absorbent articles
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such as diapers, training pants, incontinence briefs, feminine hygiene
garments or panties, bibs, hospital gowns, caps, bandages and the tike.
As used herein, the term "shear stress" refers to the distributed forces
acting tangentially to the surface of contact of the members of the
fastening device (or along the x/y plane). During the wearing of a
disposable absorbent article, shear stress tends to cause the members of
the fastening device to shift with respect to each other. Shear stress is to
be distinguished from °peel forces° which act on the fastening
portions of
the fastening device so as to separate and disengage from each other in
1 0 the z-direction. A disposable absorbent article is typically subjected to
peel forces in at least three ways. Peel forces are generated by the
movements of the wearer during use as they tend to cause the first and
second fastening portions of the fastening device to pull away from each
other, by the wearer in trying to unfasten the fastening device during wear
1 5 and by the user to check the disposable absorbent article for soiling or
to
remove the disposable absorbent article from the wearer. The fastening
device is preferably designed to have a resistance to peel forces (peel
force resistance) with respect to only the movement and wearer generated
methods. Therefore, the peel force resistance should only be great
2 0 enough to prevent failure of the fastening device during the first two
methods, but low enough to allow the user to check the disposable
absorbent article for soiling or to remove the disposable absorbent article
from the wearer without undue difficulty or tearing of other members of the
disposable absorbent article. It is desirable to design a fastening device
2 5 capable of resisting shear stresses and pee! forces generated by the
wearer, but having a peel force resistance low enough to allow the user to
easily remove the disposable absorbent article or check the disposable
absorbent article for soiling.
3 0 Refastenable mechanical fastening devices of the present
invention have been found to be particularly useful and beneficial when
applied to disposable absorbent articles. The refastenable mechanical
fastening device of the present invention comprises a female fastening
portion, which is capable of engaging a complementary male fastening
3 5 portion.
In one aspect of the present invention, a female fastening portion
for a refastenable mechanical fastening device is described. Figures 1
and 2 show a female fastening portion 30 comprising a textile material
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32, which is disposed adjacent to a substrate 34 whereby the textile is
non-adhesively bonded to the substrate 34. The basis weight of- the
textile material 32 is not greater than 60 grammes per square metre.
More specifically, the basis weight of the textile 32 is not greater than 40
grammes per square metre, preferably not greater than 34 grammes per
square metre and more preferably not greater than 28 grammes per
square metre.
The female fastening portion 30 comprises a loop type fastening
1 0 material consisting of a plurality of loops 38. The female fastening
portion
30 is a flexible textile material 32 that may comprise any suitable yam
material. The yam materials include, but are not limited to, polypropylene,
polyethylene terephthalate, polyamide or other like synthetic or natural
fibres. In a preferred embodiment of the present invention, as is seen from
1 5 Figures 2 and 3, the female fastening portion 30 is formed of a textile
material 32 having a three bar warp knit construction comprising loops
38, courses 40 {yams in the machine direction) and waies 42 (yams in
the cross machine direction). The loops 38, courses 40 and waies 42 are
preferably of polyamide. The courses 40 range from 5 to 25 courses 40
2 0 per centimetre, the wales 42 range from 3 to 12 wales 42 per centimetre
and the loops 38 range from 10 to 200 loops 38 per square centimetre.
In a more preferred embodiment of the present invention, the textile
material 32 comprises 15 courses 40 per centimetre, 5 wales 42 per
centimetre and 40 loops 38 per square centimetre. The loops 38 of the
2 5 textile material 32 may be formed with .a loop height ranging from about
0.2 to 20 millimetres, a loop denier ranging from 8 to 78 and a basis
weight, which is not greater than 60 grammes per square metre.
Typically, the basis weight is not greater than 40 grammes per square
metre, preferably not greater than 34 grammes per square metre and
3 0 more preferably, not greater than 28 grammes per square metre. The
loops 38 can be stabilised through napping, thermosetting or the like.
In another embodiment of the present invention, the female
fastening portion 30 comprises a two bar warp knit construction
3 5 comprising courses 40 ranging from 5 to 25 courses 40 per centimetre,
preferably 15 per centimetre, and wales ~t2 ranging from 3 to 12 wales 42
per centimetre, preferably 5 per centimetre.
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fn particular, the yams for the loops 38, courses 40 and waies 42
are composed of yarn having about 1 to 30 individual filaments, with
preferably 30 filaments of yam for the loops 38, 1 filament for the courses
40 and 1 filament for the wales 42. The yams typically have a denier in
the range from 8 to 78 denier. In a preferred embodiment of the present
invention, the denier value for the loops 38 is 44 denier, and for the
courses 40 and wales 42 is 22 denier, respectively.
The loops 38 are preferably constructed in such a way that the
1 0 shear stresses and the peel forces show an equivalent distribution in both
directions C and D, as is evident from Figure 4 (for example, stretch
direction of elastic members 66). The preferred pattern involves the loops
38 being oriented either all in the same direction or half of the loops 38
being oriented in one direction and the other half being oriented in the
i 5 other direction in an alternating fashion.
The textile material 32 is either thermobonded or extrusion bonded
to the substrate 34 using conventional means known to the man skilled in
the art. Thermobonding uses heat to bond or stabilise the textile material
2 0 32 to the substrate 34. Typically, the substrate 34 comprises
thermoplastic fibres. All or part of the fibres act as thermal binders, thus
eliminating the use of other types of binders, such as latex or resin. The
process is relatively simple, and the methods of thermobonding are varied
to meet the requirements for the end product. Extrusion bonding involves
2 5 the extrusion of the substrate 34 onto the textile material 32. The
substrate 34 is extruded through a die at an elevated temperature to form
the final structure which is then cooled.
In another aspect of the present invention, the female fastening
3 0 portion 30 is applied to a disposable absorbent article. Figure 4 shows
preferred embodiment of a disposable absorbent article, namely a diaper
50, embodying the present invention. Examples of the kinds of diapers
50 to which the present invention is very readily adapted are shown in
US 3,860,003 and US 4,834,735. It will be apparent from the following
3 5 description that the refastenable mechanical fastening device 5 4
illustrated and described herein may be applied to the body portion 52 of
such diapers 50. On the other hand, it will be understood that the
invention is not limited to any specific diaper construction or configuration.
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Figure 4 is a partially cut-away perspective view of a diaper 50
embodying the present invention prior to it being placed on the wearer.
As is visible from Figure 4, a preferred diaper 50 comprises a body
portion 52 and a refastenable meclhanical fastening device 54. A
preferred body portion 52 comprises ;a liquid pervious topsheet 56, an
absorbent core 58, a liquid impervious backsheet 60, and elastically
contractible leg cuffs 62; each ieg cuff 62 preferably comprising a side
flap 64 and one or more elastic members 66. For simplicity purposes,
only one elastic member 66 is shown in the side flap 64. While the
1 0 topsheet 56, the absorbent core 58, they backsheet 60, the side flaps 64,
and the elastic members 66 may be assembled in a variety of well-known
configurations, a preferred disposable diaper configuration is shown and
generally described in US 3,860,003. In this preferred diaper
configuration, the backsheet 60 is joined to the topsheet 56; the
1 5 absorbent core 58 is positioned between the topsheet 56 and the
backsheet 60; the side flaps 64 extend outwardly from and along each
side edge of the absorbent core 58;; and the elastic member 66 is
operatively associated with each side flap 64.
2 0 Figure 4 shows the body portion 52 in which the topsheet 56 and
the backsheet 60 are coextensive and have length and-width dimensions
generally larger than those of the absorbent core 58. The topsheet 56 is
superposed on the backsheet 60 thereh>y forming the periphery 68 of the
body portion 52. The periphery 68 defines the outer perimeter or in other
2 5 words the outer extent of the body portion 52. The periphery comprises
the longitudinal side edges 70 and lateral end edges 72. In ~ the
longitudinal direction, the diaper 50 has a first end region 78 and a
second end region 80.
3 0 The body portion 52 has an inside surface 74 and an outside
surface 76. In general, the outside surface 76 of the diaper 50 extends
from one edge 72 to the other end edge 72 of the diaper 50 and from one
longitudinal side edge 70 to the other longitudinal side edge 70 of the
diaper 50. When a backsheet 60 is used, it typically forms the outside
3 5 surface 76 of the body portion 52. The inside surface 74 is that surface
of
the diaper 50 opposite the outside surface 76 and in the embodiment
shown is typically formed by the topsheet 56. In general, the inside
surface 74 of the diaper 50 is that surface coextensive with the outside
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surface 76 and which is for the greater part in contact with the wearer
when the diaper 50 is wom.
The diaper 50 has a first end region 78 and a second end region
5 80 extending from the lateral end edges 72 of the diaper periphery 68
towards the lateral centreline of the diaper 50. Both the first end region
?8 and the second end region 80 extend a distance of about one-half the
length of the diaper 50 such that the end regions 78, 80 comprise each
half of the diaper 50. Both the first end region 78 and the second end
1 0 region 80 have panels 82. The panels 82 are those portions of the first
end region 78 and the second end region 80 which overlap when the
diaper 50 is fastened about the waist of the wearer. The extent to which
the end regions 78 overlap and thus the extent to which the panels 82
are formed, will depend on the overall dimensions and shape of the
1 5 diaper 50 and the size of the wearer.
The absorbent core 58 of the body portion 52 may be any
absorbent means which is generally compressible, conformable, non-
irritating to the skin of the wearer, and capable of absorbing and retaining
2 0 liquids such as urine and other certain bodily discharges. The absorbent
core 58 may be manufactured in a variety of sizes and shapes (for
example, rectangular, hour-glass, "T"-shaped, asymmetric, etc.) and from
a wide variety of liquid absorbent materials commonly used in disposable
diapers and other absorbent articles such as comminuted wood pulp
2 5 which is generally referred to as airfelt. Examples of other suitable
absorbent materials include creped cellulose wadding, meltblown
polymers including coform, crosslinked cellulosic fibers, tissue including
tissue wraps, absorbent foams, absorbent sponges, superabsorbent
polymers, absorbent gelling materials, or any equivalent materials or
3 0 combinations of materials. The configuration and construction of the
absorbent core 58 may also be varied (for example, the absorbent core
58 may have varying caliper zones, hydrophilic gradients,
superabsorbent gradients, or lower average density and lower average
basis weight acquisition zones; or may comprise one or more layers or
3 5 structures). The total absorbent capacity of the absorbent core 58 should,
however, be compatible with the design loading and the intended use of
the pull-on diaper. Further, the size and absorbent capacity of the
absorbent core 58 may be varied to accommodate wearers ranging from
infants to adults.
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The backsheet 60 is impervious to liquids (for example, urine) and
is preferably manufactured from a thin plastic film, preferably a
thermoplastic film, although other flexible liquid impervious materials may
afso be used. As used herein, the terrn "flexible" refers to materials which
are compliant and which will readily .conform to the general shape and
contours of the human body. The ba.cksheet 60 prevents the exudates
absorbed and contained in the absorbent core 58 from soiling articles
which are in contact with the diaper 50 such as undergarments and
1 0 bedding. The backsheet 60 may thus; comprise polymeric films such as
thermoplastic films of polyethylene or polypropylene, or composite
materials such as film-coated non=woven material. For economic,
aesthetic and ecological reasons, tree backsheet 60 has an average
nominal caliper, i.e., calculated caliper, of less than about 0.051
1 S millimetres, more preferably a calculatE~d caliper of from 0.020
millimetres
to 0.036 millimetres. Preferably, the backsheet 60 is a flexible
polyethylene film. As used herein, the' term "polyethylene" film refers to
films which are essentially made of polyethylene, however, it is
understood that polyethylene film will contain a variety of additives to
2 0 provide characteristics like opacity, strength requirements, colour, or
any
other desired characteristic that can be achieved through adding minor
amounts of other substances than pols~ethyiene into the films. The total
amount of additives should be less than 45 percent, preferably less than
percent, by weight of film materials. Particularly, for opacity of the film,
2 5 titanium dioxide is commonly used in a range of 2 to 6 percent, preferably
3.5 to 4.8 percent, by weight of the film. Exemplary films are manufactured
by Tredegar Industries, Inc. of Terre Haute, Ind., USA or BP-Chemical
PIasTec Rotbuchenstrasse 1, D-8000 Mlunchen, Germany.
3 0 The backsheet 60 is preferably textured to provide a more clothlike
appearance. Further, the backsheet 60 may also permit vapours to
escape from the absorbent core 58 while still preventing exudates from
passing through the backsheet 60 by, for example, being supplied with
microapertures. The size of the backsheet 60 is dictated by the size of the
3 5 absorbent core 58 and the exact diaper design selected.
The topsheet 56 of the body portion 52 of the present invention is
compliant, soft feeling and non-irritating to the skin of the wearer. Further,
the topsheet 56 is liquid pervious permivtting liquids (for example, urine) to
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readily penetrate through its thickness. A suitable topsheet 56 may be
manufactured from a wide range of materials, such as porous foams,
reticulated foams, apertured films; or woven or non-woven webs of natural
fibres (for example, wood or cotton fibres) or from a combination of natural
and synthetic fibres. Preferably, it is made of a material that isolates the
skin of the wearer from liquids retained in the absorbent core 58.
There are a number of manufacturing techniques which may be
used to manufacture the topsheet 56. For example, the topsheet 56 may
1 0 be a non-woven web of fibres. When the topsheet 56 comprises a non-
woven web, the web may be spunbonded, carded, wet-laid, melt-blown,
hydroentangled, hydroformed, combinations of the above, or the tike. An
exemplary topsheet 56 is carded and thermally bonded by means well-
known to those skilled in the art of textile materials and comprise staple
1 5 length polypropylene fibres having a denier of about 2.2 and has a basis
weight from about 15 to about 30 grammes per square metre. As used
herein, the term "staple length fibres" refer to those fibres having a length
of at least 16 millimetres. A suitable topsheet 56 is manufactured by, for
example, Veratec Inc., a division of International Paper Company, of
2 0 Walpole, Mass., USA. A topsheet 56 particularly preferred for
incontinence garments comprises a formed thermoplastic film.
The female fastening portion 30 of the fastening device 5 4
provides a means for securing itself and the male fastening portion 84
2 5 together to provide a secure side closure and to maintain the first end
region 78 and the second end region 80 in an overlapping configuration.
The female fastening portion 30 may be disposed anywhere on the
diaper 50 so long as it engages the male fastening portion 84 so as to
provide the side closure. For example, the female fastening portion 30
3 0 may be disposed on the outside surface 76 in the second end region 80,
on the inside surface 74 in the first end region 78, or on any other portion
of the diaper 50 which is disposed to engage the male fastening portion
84. In addition, the female fastening portion 30 may either be a discrete
separate element affixed to an element of the diaper 50 such as the
3 S topsheet 56 or the backsheet 60. While the female fastening portion 30
can assume varying sizes and shapes and can be provided in smaller,
more economical and ecological sizes depending on the use for which
the disposable absorbent article is designed, it preferably comprises one
or more (at least one) separate patches of material that may be larger in
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area than the hook fastening material 88 and which are secured to the
body portion 52 to allow for a maximum fit adjustment at the waist of the
wearer.
As illustrated in Figure 4, the diaper 50 has a rectangular-shaped
female fastening portion 30 secured i:o the substrate 34, the substrate 34
either being a film adjacent to the outside surface 76 of the body portion
52 or alternatively, the substrate 34 Ibeing simply the outside surface 76
of the body portion 52. For the first option comprising the film, a layer of
1 0 adhesive is interposed between the film and the outside surface 76 of the
body portion 52. The adhesive may comprise any suitable adhesive such
as a hot melt, or the like. By way of illustration, suitable adhesives are
available from Findiey Adhesives, inc. of Wauwatosa, Wis., USA under the
trade designations TEF 195 and TEF 688.
The refastenable mechanical fastening device 54 comprises a
male fastening portion 84, which comprises a hook fastening material 88.
As used herein, the term "hook fastening material" is used to designate a
material having engaging elements. It should be understood that the use
2 0 of the term hook should be non-limiting in the sense that the engaging
elements may comprise any shapes as are known in the art as long as
they are adapted to engage a complementary female fastening portion
30. As is visible from Figure 4, each reale fastening portion 84 provides a
fastening means for engaging the female fastening portion 30 so as to
2 5 provide a secure side closure for the ~jiaper 50. Thus, the male fastening
portion 84 comprises at least the hook fastening material 88. Each male
fastening portion 84 also preferably comprises a means for positioning
the hook fastening material 88 adjacent to the female fastening portion
30 so as to achieve a side closure. 'thus, the male fastening portion 84
3 0 may comprise any of the well-knovwn configurations and securement
means for achieving a side closure on a diaper 50 such as an inner
fastening member secured to the in:~ide surface 74 and/or the outside
surface 76 of the body portion 52, l:ape tabs, or belts. An exemplary
embodiment of an inner fastening member is described in US 4,699,622.
3 5 An embodiment of an incontinence undergarment using a belt suspension
system is disclosed in US 4,315,508.
Each male fastening portion 84 most preferably comprises a tape
tab 86. Any of the well-known confi~~uration and constructions of a tape
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tab 86 may be used. The tape tab 86 is provided on both longitudinal
side edges 70 of the body portion 52, most preferably in the first end
region 78. A particularly preferred tape tab 86 has a tape tab fastening
surface 90 and a tab backing surface 92. The tape tab fastening surface
90 is the surface of the tape tab 86 designed to engage the female
fastening portion 30 of the present invention. Thus, the tape tab fastening
surface 90 of the tape tab 86 will generally correspond to the inside
surface 74 of the body portion 52. The tape tab backing surface 92 is
that surface opposite to the tape tab fastening surface 90 and generally
1 0 corresponds to the outside surface 76 of the body portion 52. The tape
tab backing surface 92 is thus generally exposed during wear of the
diaper 50.
The hook fastening material 88 is preferably joined to either the
I 5 body portion 52 or the tape tab 86. As used herein, the term
"joined°
encompasses configurations whereby the hook fastening material 88 is
releasably secured to the diaper 50 so the hook fastening material 88
may be removed from the diaper 50 or its location during use and
whereby the hook fastening material 88 is securely fastened to the diaper
2 0 50. Joined is also used to denote that the hook fastening material 88
may be directly joined to the diaper 50 or may be indirectly joined to the
diaper 50 such as by releasably securing or affixing the hook fastening
material 88 to an intermediate member which, in turn, is releasably
secured or affixed to the diaper 50. Preferably, as shown in Figure 4, the
2 5 hook fastening material 88 is directly affixed to the connective portion
102 of the tape tab 86 by a second tab attachment means 112.
In addition, the hook fastening material 88 may be positioned
anywhere on the diaper 50. When the male fastening portion 84
3 0 comprises an inner fastening member, the hook fastening material 88 is
preferably positioned in the panels 82 of the first end region 78 adjacent
to the longitudinal side edges 70. When the male fastening portion 84
comprises a tape tab 86, the hook fastening material 88 is preferably
positioned either on all of or at least a portion of the tape tab fastening
3 5 surface 90, or preferably on all of or at least a portion of the
connective
portion 102. Most preferably, the hook fastening material 88 is disposed
on the connective portion 702 on the tape tab fastening surface 90.
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In order to measure the shear stresses and peel forces of the
female fastening portion 30 and thE~ male fastening portion 84 of the
refastenable mechanical fastening device 54, reference is made to a
suitable test method, which is described below in the section entitled
"Description of test procedure". The values measured for a selection of
samples (i.e., for the female fastening portion 30 when engaged with the
male fastening portion 84) were reported to be greater than 500 grammes
for the shear stresses and to be at least 85 newtons per metre for the peel
force with preferably 4 sigma < (average measurement - 85 newtons per
metrel.
In a further embodiment of the present invention, where the
substrate 34 comprises a film adjacent to the outside surface 76 of the
body portion 52 as described hereinabove, the film is printed. For the
1 5 alternative embodiment of the present/ invention where the substrate 34
comprises the outside surface 76 of the body portion 52, the outside
surface 76 of the body portion 52 may be printed. Printing is done by
means known to the man skilled in the .art.
2 0 In use, the diaper 50 is applied to the wearer by positioning the first
end region 78 under the back of the wearer and drawing the remainder of
the diaper 50 between the legs of the wearer so the second end region
80 is positioned across the front of the wearer. The connective portion
102 of the tape tabs 86 are then positioned adjacent to the female
2 5 fastening portion 30 positioned on the outer surface 76 of the second end
region 80 so the hook fastening material 88 which is disposed on the
tape tab fastening surface 90 will respectively engage the textile material
32 of the female fastening portion 30 to form a side closure.
3 0 Description of test procedure
For the purposes of the present invention, a method is herein described
which describes the procedure for measuring the shear stresses (using a
500 gramme weight) and peel force c~f the female fastening portion 30
and male fastening portion 84 for a refastenable mechanical fastening
3 5 device 54 according to the teachings of the present invention. The testing
method is applicable to a female fastening portion 30 in the form of a loop
raw material and a male fastening portion 84 in the form of a hook .raw
material.
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A~oaratus reguired
Conditioned room Controlled to 22 degrees Celsius ~ 2
degrees Celsius, 50 percent ~ 2 percent
relative humidity.
Scissors Usual pair.
Test stand Clamps designed to hold the 500
gramme weight and mounted in such a
1 0 way so that the sample can hang free.
Paper strips Cut width of 2.54 centimetres from
copying paper 80 grammes per square
metre SB or equivalent.
Loop material As described above.
Hook material Normal production material specification
85379.
Inch cutter Supplied from Thwing Albert Instrument
Company, Philadelphia, USA.
500 gramme weight Usual type with clamp attached.
Electronic tensile tester Supplied from Zwick 1445, Zwick GmbH
& Co., 7900 Ulm with a 100 newton load
cell or equivalent.
3 0 Saml~~rel are ation
Condition the test material at 22 degrees Celsius and 50 percent relative
humidity for a minimum of two hours prior to testing. Prepare a hook
sample strip for each loop sample strip to be tested.
3 5 Loop strip preparation:-
With an inch cutter, cut a strip (2.54 centimetres machine direction by
cross direction width) out of the loop material. Cut strips in half. Be aware
of material orientation - loops up and loops down.
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Hook material preparation:-
Remove the outer layer of the sample roll to ensure no contaminated or
damaged hook material is measured. Ensure that the hooks unwind from
the right side. Tape the hooks onto a 2.54 centimetre wide and at least
100 millimetre long paper strip.
he r
- Take the loop strip and insert in the clip of the test stand.
- Take the hook strip and clamp it into the 500 gramme weight clip.
1 0 - Take the hook strip with the weight ;end press it into the loop strip
using
the thumb and forefinger.
- Release it carefully and let it hang for 5 seconds.
- Remove the weight from the hook strip.
- Remove the sheared sample from the test stand and perform the peel
1 5 test on the tensile tester.
Instrumen~,~rg~ aration
Before beginning the peel test, the tensile tester needs to be calibrated.
2 0 Reference should be made to the manufacturer's instruction manual. The
parameters should be set as follows:
Gauge length - 50 millimetres (0.2 inches)
Pre-force - 0.2 newtons
2 5 Crosshead speed - 305 millimetres per minute
(12 inches per minute)
Measuring distance _ 40 millimetres
Peel testtest
3 0 - Place the hook strip into the upper (or moving) jaw of the tensile
tester.
- Place the loop strip in the lower (or static) jaw.
- Start the crosshead to initiate the test.
- Repeat the procedure for both direction configurations of closure.
3 5 Re orting of data
- Report each sample that fails the shear test.
- Report the peak force (newton) and average force (newton) for the peel
test. Samples which failed the shear test will be reported as zero.
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- Calculate the total average, standard deviation (maximum and
minimum) and the average, standard deviation (maximum and
minimum) for each orientation separately.
- Print the graphs of the peel force curves.
