U.S. patent application number 11/636858 was filed with the patent office on 2008-06-12 for fastener having adjustable fastening strength.
Invention is credited to Eric C. Steindorf.
Application Number | 20080134476 11/636858 |
Document ID | / |
Family ID | 39496268 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080134476 |
Kind Code |
A1 |
Steindorf; Eric C. |
June 12, 2008 |
Fastener having adjustable fastening strength
Abstract
Clothlike materials may become abraded upon disengagement of
mechanical fasteners. This abrasion may cause a decrease in
aesthetic appeal, as well as a decrease in functionality of
attachment systems. As a result, there has remained a need for
improved fastening systems. Moreover, there has remained a need for
improved fastening systems for disposable absorbent articles.
Inventors: |
Steindorf; Eric C.;
(Roswell, GA) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.;Catherine E. Wolf
401 NORTH LAKE STREET
NEENAH
WI
54956
US
|
Family ID: |
39496268 |
Appl. No.: |
11/636858 |
Filed: |
December 11, 2006 |
Current U.S.
Class: |
24/452 |
Current CPC
Class: |
Y10T 24/2792 20150115;
A61F 13/625 20130101; A44B 18/008 20130101; A44B 18/0003
20130101 |
Class at
Publication: |
24/452 |
International
Class: |
A44B 18/00 20060101
A44B018/00 |
Claims
1. A fastening system suitable for incorporation into a disposable
absorbent article, the fastening system comprising: a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component,
wherein the fastening system has a first normalized peak shear
force to disengage the female component from the male component
when the male component is stretched 0%, the fastening system has a
second normalized peak shear force to disengage the female
component from the male component when the male component is
stretched 10%, the first normalized peak shear force being at least
10% greater than the second normalized peak shear force.
2. The fastening system of claim 1, wherein the first normalized
peak shear force is at least 20% greater than the second normalized
peak shear force.
3. The fastening system of claim 1, wherein at least a portion of
the male component is stretchable at least 10% when loaded at 250
g/in.
4. The fastening system of claim 1, wherein at least a portion of
the male component is stretchable at least 15% when loaded at 250
g/in.
5. The fastening system of claim 1, wherein at least a portion of
the male component is elastic.
6. A fastening system suitable for incorporation into a disposable
absorbent article, the fastening system comprising: a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component,
wherein at least a portion of the plurality of hook elements have a
stem and a cap, the cap defining a cap angle; wherein the fastening
system has a first normalized peak shear force to disengage the
female component from the male component and a first average cap
angle when the male component is stretched 0%, the fastening system
has a second normalized peak shear force to disengage the female
component from the male component and a second average cap angle
when the male component is stretched 10%, the first normalized peak
shear force being greater than the second normalized peak shear
force, and the second average cap angle being greater than the
first average cap angle.
7. The fastening system of claim 6, wherein the second average cap
angle is at least 20 degrees greater than the first average cap
angle.
8. The fastening system of claim 6, wherein the second average cap
angle is at least 90 degrees.
9. The fastening system of claim 6, wherein the first normalized
peak shear force is at least 10% greater than the second normalized
peak shear force.
10. The fastening system of claim 6, wherein at least a portion of
the male component is stretchable at least 10% when loaded at 250
g/in.
11. The fastening system of claim 6, wherein at least a portion of
the male component is stretchable at least 15% when loaded at 250
g/in.
12. The fastening system of claim 6, wherein at least a portion of
the male component is elastic.
13. A fastening system suitable for incorporation into a disposable
absorbent article, the fastening system comprising: a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component,
wherein the fastening system has a first normalized peak shear
force to disengage the female component from the male component
when the male component is stretched 0%, the fastening system has a
second normalized peak shear force to disengage the female
component from the male component when the male component is
stretched 10%, the first normalized peak shear force being at least
10% less than the second normalized peak shear force.
14. The fastening system of claim 13, wherein the first normalized
peak shear force is at least 20% less than the second normalized
peak shear force.
15. The fastening system of claim 13, wherein at least a portion of
the male component is stretchable at least 10% when loaded at 250
g/in.
16. The fastening system of claim 13, wherein at least a portion of
the male component is stretchable at least 15% when loaded at 250
g/in.
17. The fastening system of claim 13, wherein at least a portion of
the male component is elastic.
18. A fastening system suitable for incorporation into a disposable
absorbent article, the fastening system comprising: a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component,
wherein at least a portion of the plurality of hook elements have a
stem and a cap, the cap defining a cap angle, wherein the fastening
system has a first normalized peak shear force to disengage the
female component from the male component and a first average cap
angle when the male component is stretched 0%, the fastening system
has a second normalized peak shear force to disengage the female
component from the male component and a second average cap angle
when the male component is stretched 10%, the first normalized peak
shear force being less than the second normalized peak shear force,
and the second average cap angle being less than the first average
cap angle.
19. The fastening system of claim 18, wherein the second average
cap angle is at least 20 degrees less than the first average cap
angle.
20. The fastening system of claim 18, wherein the first average cap
angle is at least 90 degrees.
21. The fastening system of claim 18, wherein the first normalized
peak shear force is at least 10% less than the second normalized
peak shear force.
22. The fastening system of claim 18, wherein at least a portion of
the male component is stretchable at least 10% when loaded at 250
g/in.
23. The fastening system of claim 18, wherein at least a portion of
the male component is stretchable at least 15% when loaded at 250
g/in.
24. The fastening system of claim 18, wherein at least a portion of
the male component is elastic.
Description
BACKGROUND
[0001] The present invention relates to improved fastening systems.
More particularly, the present invention relates to improved hook
and loop fastening systems for disposable absorbent articles.
[0002] Conventional disposable absorbent articles, such as
disposable diapers, have typically included a bodyside liner, an
outer cover, and an absorbent core located between the outer cover
and the bodyside liner. The disposable absorbent articles have
generally defined a front region, a rear region, and a crotch
region which extends between and connects the front and rear
regions. Such conventional disposable absorbent articles have also
included fastening systems which are configured to secure the
article on the wearer's waist. The disposable absorbent articles
have also been constructed with various types of elasticized
portions at the waist and leg opening regions. Such elasticized
portions have been used to reduce the leakage of body exudates from
the disposable absorbent article and improve the appearance and fit
of the article about the wearer.
[0003] Typically, the fastening systems on conventional disposable
absorbent articles have included a pair of fasteners located on the
outermost corners of the article in one of the waist regions. Such
fasteners have been configured to releasably engage a complimentary
fastener in the opposite waist region of the disposable absorbent
article. For example, the fastening systems have included a pair of
mechanical fasteners, such as hook material, located on the
outermost corners of the disposable absorbent article in the rear
region of the article. Such systems have also included a
complimentary fastener, such as a loop material panel, located on
the outer surface of the outer cover of the disposable absorbent
article in the front region of the article. In such a
configuration, the disposable absorbent article has been positioned
between the legs of the wearer and the hook material has been
releasably attached to the loop material panel to secure the
article about the waist of the wearer. In some disposable absorbent
articles the loop material panel has been removed and the hook
material has been releasably attached to the outer cover of the
diaper. This is known as a fasten anywhere configuration.
[0004] However, conventional disposable absorbent articles which
are configured as described above have exhibited several
shortcomings. For example, with the desire for disposable absorbent
articles to be more clothlike, manufacturers have made the outer
cover and the loop material increasingly fluffier, softer, and
correspondingly more susceptible to abrasion. As a result, these
clothlike materials become abraded upon disengagement of the
mechanical fasteners. This abrasion may cause a decrease in
aesthetic appeal, as well as a decrease in functionality of the
attachment system.
[0005] As a result, there has remained a need for improved
fastening systems. Moreover, there has remained a need for improved
fastening systems for disposable absorbent articles.
SUMMARY
[0006] The present inventors undertook intensive research and
development efforts concerning improving fastening systems. The
present invention is directed in part to a fastening system
suitable for incorporation into a disposable absorbent article. The
fastening system may include a female component; and a male
component having a plurality of hook elements adapted for
releasable engagement with the female component. Further, the
fastening system has a first normalized peak shear force to
disengage the female component from the male component when the
male component is stretched 0%. The fastening system also has a
second normalized peak shear force to disengage the female
component from the male component when the male component is
stretched 10%. The first normalized peak shear force is at least
10% greater than the second normalized peak shear force.
[0007] Another aspect of the present invention is directed to a
fastening system suitable for incorporation into a disposable
absorbent article. The fastening system may include a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component. At
least a portion of the plurality of hook elements have a stem and a
cap, and the cap defines a cap angle. Further, the fastening system
has a first normalized peak shear force to disengage the female
component from the male component and a first average cap angle
when the male component is stretched 0%. The fastening system has a
second normalized peak shear force to disengage the female
component from the male component and a second average cap angle
when the male component is stretched 10%. The first normalized peak
shear force is greater than the second normalized peak shear force,
and the second average cap angle is greater than the first average
cap angle.
[0008] Another aspect of the present invention is directed to a
fastening system suitable for incorporation into a disposable
absorbent article. The fastening system may include a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component.
Further, the fastening system has a first normalized peak shear
force to disengage the female component from the male component
when the male component is stretched 0%. The fastening system has a
second normalized peak shear force to disengage the female
component from the male component when the male component is
stretched 10%. Further, the first normalized peak shear force being
at least 10% less than the second normalized peak shear force.
[0009] Another aspect of the present invention is directed to a
fastening system suitable for incorporation into a disposable
absorbent article. The fastening system may include a female
component; and a male component having a plurality of hook elements
adapted for releasable engagement with the female component. At
least a portion of the plurality of hook elements have a stem and a
cap, the cap defining a cap angle. The fastening system having a
first normalized peak shear force to disengage the female component
from the male component and a first average cap angle when the male
component is stretched 0%. The fastening system having a second
normalized peak shear force to disengage the female component from
the male component and a second average cap angle when the male
component is stretched 10%. The first normalized peak shear force
being less than the second normalized peak shear force, and the
second average cap angle being less than the first average cap
angle.
DRAWINGS
[0010] The foregoing and other features, aspects and advantages of
the present invention will become better understood with regard to
the following description, appended claims and accompanying
drawings where:
[0011] FIG. 1 illustrates a plan view of a disposable absorbent
article in an unfolded, flat-out, uncontracted state (i.e., with
all elastic induced gathering and contraction removed), with the
bodyfacing surface of the article facing the viewer and with
portions of the article partially cut away to illustrate underlying
features;
[0012] FIG. 2 illustrates a plan view of a disposable absorbent
article in an unfolded, flat-out, uncontracted state, with the
garment facing surface of the article facing the viewer and with
portions of the article partially cut away to illustrate underlying
features;
[0013] FIG. 3A illustrates a side view of a first hook
material;
[0014] FIG. 3B illustrates a side view of the hook material of FIG.
3A while extended;
[0015] FIG. 4A illustrates a side view of a second hook
material;
[0016] FIG. 4B illustrates a side view of the hook material of FIG.
4A while extended;
[0017] FIG. 5A illustrates a side view of a third hook
material;
[0018] FIG. 5B illustrates a side view of the hook material of FIG.
5A while extended;
[0019] FIG. 6A illustrates a side view of a fourth hook
material;
[0020] FIG. 6B illustrates a side view of the hook material of FIG.
6A while extended; and
[0021] FIG. 7 illustrates a representative test sample.
DESCRIPTION
[0022] The present invention relates to improved fasteners and
improved fasteners for use in disposable absorbent articles. As
used herein, the term "disposable" refers to articles which are
intended to be discarded after a limited use and which are not
intended to be laundered or otherwise restored for reuse. The
disposable absorbent articles of the present invention will be
described in terms of a disposable diaper which is adapted to be
worn by infants about the lower torso. It is understood that the
improved fastening system of the present invention is equally
adaptable for use with other types of disposable absorbent articles
such as adult incontinence garments, children's training pants,
surgical gowns and the like.
[0023] With regard to the designated surfaces of a disposable
absorbent article and its components, the various upper or
bodyfacing surfaces are configured to face toward the body of the
wearer when the disposable absorbent article is worn by the wearer
for ordinary use. The various opposing, lower, or garment facing
surfaces are configured to face away from the wearer's body when
the disposable absorbent article is worn by the wearer.
[0024] As used herein, reference to two materials or elements being
"joined" is intended to refer to the situation wherein the two
materials or elements are directly joined to one another, where
they are indirectly joined to one another, or where they are
indirectly joined to an intermediate element. Similarly, methods of
joining two materials or elements include forming the elements or
materials integrally, attaching the elements together such as
through the use of adhesive bonds, sonic bonds, thermal bonds,
pinning, or stitching, or a variety of other attachment techniques
known in the art, as well as combinations thereof.
[0025] "Stretchable" refers to materials which are either elastic
or extensible, that is materials which when elongated in one or
more dimensions either exert a force tending to move the material
at least partially to its original dimensions (elastic), or which
remain in the elongated configuration (extensible).
[0026] It should be noted that the stretch, elastic or extensible
properties of a stretchable material are determined when the
material is dry. Additionally, the percentage of elongation,
extension, or permanent deformation can be determined in accordance
with the following formula:
100*[(L-L.sub.o)/(L.sub.o)] [0027] where: L=elongated length; and
[0028] L.sub.o=initial length.
[0029] Referring now to the drawings, FIG. 1 illustrates a
disposable absorbent article such as a disposable diaper (30) in an
unfolded, flat-out, uncontracted state (i.e., with all elastic
induced gathering and contraction removed). Portions of the
structure are partially cut away to more clearly show the interior
construction of the diaper (30), with the surface of the diaper
(30) which contacts the wearer facing the viewer. FIGS. 1 and 2
illustrate a disposable diaper (30) as having a front region (32),
a rear region (34) and a crotch portion (36) located between the
front and rear regions. The diaper (30) comprises a backsheet (38),
a topsheet (40), and an absorbent core (42) situated between the
backsheet and the topsheet. The outer edges of the diaper (30)
define a periphery (44) with transversely opposed, longitudinally
extending side edges (46); longitudinally opposed, transversely
extending end edges (48); and a system of elastomeric gathering
members, such as a system including leg elastics (50) and waist
elastics (52). The longitudinal side edges (46) define the leg
openings (54) for the diaper (30), and optionally, are curvilinear
and contoured. The transverse end edges (48) are illustrated as
straight, but optionally, may be curvilinear. The diaper (30) may
also comprise additional components to assist in the acquisition,
distribution and storage of bodily waste. For example, the diaper
(30) may comprise a transport layer, such as described in U.S. Pat.
No. 4,798,603, issued to Meyer et al., or a surge management layer,
such as described in European Patent Application Publication No. 0
539 703, published May 5, 1993.
[0030] The diaper (30) generally defines a longitudinally extending
length dimension (56), and a laterally extending width dimension
(58), as representatively illustrated in FIG. 1. The diaper (30)
may have any desired shape, such as rectangular, I-shaped, a
generally hourglass shape, or a T-shape.
[0031] The backsheet (38) defines a length and a width which, in
the illustrated version, coincide with the length and width of the
diaper (30). The absorbent core (42) generally defines a length and
width which are less than the length and width of the backsheet
(38), respectively. Thus, marginal portions of the diaper (30),
such as marginal sections of the backsheet (38), may extend past
the transversely opposed, longitudinally extending terminal side
edges (60) and/or the longitudinally opposed, transversely
extending terminal end edges (62) of the absorbent core (42) to
form side margins (64) and end margins (66) of the diaper (30). The
topsheet (40) is generally coextensive with the backsheet (38), but
may optionally cover an area which is larger or smaller than the
area of the backsheet, as desired. The backsheet (38) and topsheet
(40) are intended to face the garment and body of the wearer,
respectively, while in use. As used herein when describing the
topsheet (40) in relation to the backsheet (38) and vice versa, the
term "associated" encompasses configurations in which the topsheet
is directly joined to the backsheet, and configurations where the
topsheet is indirectly joined to the backsheet by affixing portions
of the topsheet to intermediate members which in turn are affixed
to at least portions of the backsheet. The topsheet (40) and the
backsheet (38) can, for example, be joined to each other in at
least a portion of the diaper periphery (44) by attachment
mechanisms (not shown) such as adhesive bonds, sonic bonds, thermal
bonds, pinning, stitching, or a variety of other attachment
techniques known in the art, as well as combinations thereof.
[0032] The topsheet (40) suitably presents a bodyfacing surface
which is compliant, soft feeling, and non-irritating to the
wearer's skin. Further, the topsheet (40) may be less hydrophilic
than the absorbent core (42), to present a relatively dry surface
to the wearer, and is sufficiently porous to be liquid permeable,
permitting liquid to readily penetrate through its thickness. A
suitable topsheet (40) may be manufactured from a wide selection of
web materials, such as porous foams, reticulated foams, apertured
plastic films, natural fibers, synthetic fibers (for example,
polyester or polypropylene fibers), or a combination of natural and
synthetic fibers. The topsheet (40) is suitably employed to help
isolate the wearer's skin from liquids held in the absorbent core
(42).
[0033] Various woven and nonwoven fabrics may be used for the
topsheet (40). For example, the topsheet (40) may be composed of a
meltblown or spunbonded web of polyolefin fibers. The topsheet (40)
may also be a bonded-carded web composed of natural and/or
synthetic fibers. The topsheet (40) may be composed of a
substantially hydrophobic material and the hydrophobic material
may, optionally, be treated with a surfactant, or otherwise
processed, to impart a desired level of wettability and
hydrophilicity. Specifically, the topsheet (40) may be a nonwoven,
spunbond, polypropylene fabric composed of about 2.8 to about 3.2
denier fibers formed into a web having a basis weight of about 22
gsm and a density of about 0.06 g/cc.
[0034] The topsheet (40) may also be surface treated with about 0.3
weight percent of a surfactant mixture that contains a mixture of
AHCOVEL Base N-62 surfactant and GLUCOPON 220UP surfactant in about
a 3:1 ratio based on a total weight of the surfactant mixture. The
AHCOVEL Base N-62 surfactant is purchased from Hodgson Textile
Chemicals Inc., a business having offices in Mount Holly, N.C., and
comprises a blend of hydrogenated ethoxylated castor oil and
sorbitan monooleate in a 55:45 weight ratio. The GLUCOPON 220UP
surfactant is purchased from Henkel Corporation, Gulph Mills, Pa.,
and comprises alkyl polyglycoside. The surfactant may also include
additional ingredients such as aloe. The surfactant may be applied
by any conventional means, such as spraying, printing, brush
coating, foam or the like. The surfactant may be applied to the
entire topsheet (40) or may be selectively applied to particular
sections of the topsheet, such as the medial section along the
longitudinal centerline of a diaper, to provide greater wettability
of such sections.
[0035] The backsheet (38) may suitably be composed of a material
which is either liquid permeable or liquid impermeable. It is
generally desirable that the backsheet (38) be formed from a
material which is substantially liquid impermeable. For example, a
typical backsheet (38) can be manufactured from a thin plastic film
or other flexible liquid impermeable material. Moreover, the
backsheet (38) may be formed from a polyethylene film having a
thickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0
mils). If desirous of presenting the backsheet (38) with a more
cloth-like feel, the backsheet may comprise a polyethylene film
having laminated to the lower or opposing surface thereof a
nonwoven web, such as a spunbond web of polyolefin fibers. For
example, a polyethylene film having a thickness of about 0.015 mm
(0.6 mil) may have thermally laminated thereto a spunbond web of
polyolefin fibers, which fibers have a thickness of about 1.5 to
about 2.5 denier per filament, which nonwoven web has a basis
weight of about 24 gsm (0.7 osy). Methods of forming such
cloth-like outer covers are known to those skilled in the art.
Further the backsheet (38) may be a stretchable material, a method
of forming such a material may be found in U.S. Pat. No. 5,226,992
issued to Morman, further various examples of extensible materials
are described in U.S. Pat. No. 6,264,641 issued to VanGompel et
al.; the entire disclosures of which are hereby incorporated by
reference in a manner that is consistent herewith
[0036] Further, the backsheet (38) may be formed of a woven or
nonwoven fibrous web layer which has been totally or partially
constructed or treated to impart a desired level of liquid
impermeability to selected regions that are adjacent or proximate
the absorbent core (42). Still further, the backsheet (38) may
optionally be composed of micro-porous "breathable" material which
permits vapors to escape from the absorbent core (42) while still
preventing liquid exudates from passing through the backsheet.
[0037] The absorbent core (42) may comprise a matrix of hydrophilic
fibers, such as a web of cellulosic fluff, mixed with particles of
a high-absorbency material commonly known as superabsorbent
material. In a particular version, the absorbent core (42)
comprises a mixture of superabsorbent hydrogel-forming particles
and wood pulp fluff. The wood pulp fluff may be exchanged with
synthetic polymeric, meltblown fibers or with a combination of
meltblown fibers and natural fibers. The superabsorbent particles
may be substantially homogeneously mixed with the hydrophilic
fibers or may be non-uniformly mixed.
[0038] The absorbent core (42) may have any of a number of shapes.
For example, the absorbent core (42) may be rectangular, I-shaped
or T-shaped. It is often considered as desirable for the absorbent
core (42) to be narrower in the crotch portion than the rear or
front region(s).
[0039] The high-absorbency material can be selected from natural,
synthetic and modified natural polymers and materials. The
high-absorbency materials can be inorganic materials, such as
silica gels, or organic compounds, such as crosslinked polymers.
The term "crosslinked" refers to any means for effectively
rendering normally water-soluble materials substantially water
insoluble, but swellable. Such means can comprise, for example,
physical entanglement, crystalline domains, covalent bonds, ionic
complexes and associations, hydrophilic associations, such as
hydrogen bonding, and hydrophobic associations or Van der Waals
forces.
[0040] Examples of synthetic, polymeric, high-absorbency materials
include the alkali metal and ammonium salts of poly(acrylic acid)
and poly(methacrylic acid), poly(acrylamides), poly(vinyl ethers),
maleic anhydride copolymers with vinyl ethers and alpha-olefins,
poly(vinyl pyrolidone), poly(vinyl morpholinone), poly(vinyl
alcohol), and mixtures and copolymers thereof. Further polymers
suitable for use in the absorbent core include natural and modified
natural polymers, such as hydrolyzed acrylonitrile-grafted starch,
acrylic acid grafted starch, methyl cellulose, carboxymethyl
cellulose, hydroxypropyl cellulose, and the natural gums, such as
alginates, xanthum gum, locust bean gum, and the like. Mixtures of
natural and wholly or partially synthetic absorbent polymers can
also be useful. Processes for preparing synthetic, absorbent
gelling polymers are disclosed in U.S. Pat. No. 4,076,663, issued
to Masuda et al., and U.S. Pat. No. 4,286,082, issued to
Tsubakimoto et al.
[0041] The high-absorbency material may be in a variety of
geometric forms. It is desired that the high-absorbency material be
in the form of discrete particles. However, the high-absorbency
material may also be in the form of fibers, flakes, rods, spheres,
needles, or the like. Often, the high-absorbency material is
present in the absorbent core (42) in an amount of from about 5 to
about 100 weight percent based on total weight of the absorbent
core.
[0042] The disposable absorbent articles described herein also
comprise fasteners (82) for securing the absorbent article about
the waist of the wearer. The illustrated versions of the diaper
(30) comprise such fasteners (82). In at least one version, the
fasteners (82) are situated in the rear region (34) of the diaper
(30), and located inboard each longitudinal extending side edge
(46). The fasteners (82) may be configured to encircle the hips of
the wearer and engage the backsheet (38) of the front region (32)
of the diaper (30) for holding the diaper (30) on the wearer.
Desirably, the fasteners (82) are releasably engageable directly
with the garment facing surface of the backsheet (38). Desirably,
the fasteners (82) comprise a mechanical fastening system.
Alternatively, the diaper (30) may comprise a fastening panel (68)
situated in the front region (32) of the garment facing surface of
the backsheet (38). In such a configuration, the fasteners (82) are
releasably engageable with the fastening panel (68) to maintain the
diaper (30) about the waist of the wearer. Such an arrangement
provides the ability to vary the size of the waist opening in very
small increments over a wide range to fit the waist of the wearer.
The fasteners (82) may have a variety of shapes and sizes which
provide the desired fastening of the diaper (30) about the waist of
the wearer.
[0043] Desirably, the first fastener component and cooperating
fastener component comprise complementary elements of a
cooperatively interengaging mechanical fastening system. The
mechanical fastener components can be provided by mechanical-type
fasteners such as hooks and the like, which comprise cooperating
and complementary mechanically interlocking components.
[0044] As shown in FIGS. 1 and 2, for example, the mechanical
fastening system may be a hook-and-loop type of fastening system.
Such fastening systems typically comprise engagement members having
the form of a "hook" or hook-like male component and comprise a
cooperating "loop" or loop-like female component, which engages and
releasably interconnects with the hook component. Desirably, the
interconnection is selectively releasable and re-attachable.
Conventional systems are, for example, available under the VELCRO
trademark.
[0045] A configuration which employs a selectively releasable,
inter-engaging mechanical fastening system can, for example, locate
the first fastener component on the ear (89), and can locate the
cooperating, second fastener component on the fastening panel (68).
For example, with the representatively shown hook-and-loop
fastener, the fastening component, which is attached to the ear
(89), may comprise a hook type of mechanical engagement element and
the complementary fastening component is the fastening panel (68)
which can comprise a loop type of fastening element.
[0046] It should also be readily apparent that, in the various
configurations of the invention, the relative positions and/or
materials of the first fastening component and its cooperating,
complementary fastening component can be transposed.
[0047] Examples of traditional hook-and-loop fastening systems and
components are described in U.S. Pat. No. 5,019,073 issued to
Roessler et al, the entire disclosure of which is hereby
incorporated by reference in a manner that is consistent herewith.
Other examples of hook-and-loop fastening systems are described in
U.S. Pat. Nos. 5,605,735 and 6,030,373 issued to VanGompel et al.;
the entire disclosures of which are hereby incorporated by
reference in a manner that is consistent herewith.
[0048] The loop material can comprise a nonwoven, woven, or knit
fabric. For example, a suitable loop material fabric can be
composed of a 2 bar, warp knit fabric of the type available from
Guilford Mills, Inc., Greensboro, N.C. under the trade designation
#34285, as well as other types of knit fabrics. Suitable loop
materials are also available from the 3M Company, which has
distributed a nylon woven loop under their SCOTCHMATE brand. The 3M
Company has also distributed a linerless loop web with adhesive on
the backside of the web and 3M knitted loop tape.
[0049] The loop material may also comprise a nonwoven fabric having
continuous bonded areas defining a plurality of discrete unbonded
areas. The fibers or filaments within the discrete unbonded areas
of the fabric are dimensionally stabilized by the continuous bonded
areas that encircle or surround each unbonded area, such that no
support or backing layer of film or adhesive is required. The
unbonded areas are specifically designed to afford spaces between
fibers or filaments within the unbonded area that remain
sufficiently open or large to receive and engage hook elements of
the complementary hook material. In particular, a pattern-unbonded
nonwoven fabric or web may comprise a spunbond nonwoven web formed
of single component or multi-component melt-spun filaments. At
least one surface of the nonwoven fabric can comprise a plurality
of discrete, unbonded areas surrounded or encircled by continuous
bonded areas. The continuous bonded areas dimensionally stabilize
the fibers or filaments forming the nonwoven web by bonding or
fusing together the portions of the fibers or filaments that extend
outside of the unbonded areas into the bonded areas, while leaving
the fibers or filaments within the unbonded areas substantially
free of bonding or fusing. The degree of bonding or fusing within
the bonding areas desirably is sufficient to render the nonwoven
web non-fibrous within the bonded areas, leaving the fibers or
filaments within the unbonded areas to act as "loops" for receiving
and engaging hook elements. Examples of unmodified, suitable
point-unbonded fabrics are described in U.S. Pat. No. 5,858,515,
issued to Stokes et al., the entire disclosure of which is
incorporated herein by reference in a manner that is consistent
herewith.
[0050] As used herein, the term "spunbond web" refers to a web
formed by extruding a molten thermoplastic material as filaments
from a plurality of fine, usually circular, capillaries with the
diameter of the extruded filaments then being rapidly reduced, for
example, by fluid-drawing or other well known spunbonding
mechanisms. The production of spunbond nonwoven webs is illustrated
in U.S. Pat. No. 4,340,563, issued to Appel, et al., the entire
disclosure of which is incorporated herein by reference in a manner
that is consistent herewith.
[0051] The loop material need not be limited to a discrete or
isolated patch on the outward surface of the article. Instead, the
loop material can be provided by a substantially continuous, outer
fibrous layer which is assembled, integrated or otherwise joined to
extend over a predetermined surface area of the desired article.
For example, the outer fibrous layer may be arranged to extend over
substantially the total exposed surface area of a cloth-like outer
cover employed with the article. Further, the outer cover can
comprise an outer nonwoven layer that functions as a cooperating
fastener component.
[0052] The engagement force between the selected first fastener
component and its appointed and cooperating second fastener
component should be large enough and durable enough to provide an
adequate securement of the article on the wearer during use. In
particular arrangements, especially where there are sufficiently
high levels of engagement shear force provided by the fastening
system, the fastening engagement may provide a peel force value of
not less than a minimum of about 40 grams-force (gmf) per inch of
the "width" of engagement between the first and second fastener
components. In further arrangements, the fastening engagement may
provide a peel force value of not less than about 100 gmf/inch to
provide improved advantages. In desired configurations, the
fastening engagement may provide a peel force value of not less
than about 200 gmf per inch of the "width" of engagement between
the first and second fastener components. Alternatively, the peel
force is not less than about 300 gmf/inch, and optionally is not
less than about 400 gmf/inch to further provide improved benefits.
In other aspects, the peel force is not more than about 1,200
gmf/inch. Alternatively, the peel force is not more than about 800
gmf/inch, and optionally is not more than about 600 gmf/inch to
provide improved performance.
[0053] The engagement force between the selected first fastener
component and its appointed and cooperating second fastener
component may additionally provide a shear force value of not less
than about 400 gmf per square inch of the area of engagement
between the first and second fastener components. Alternatively,
the shear force is not less than about 1,000 gmf/in.sup.2, and
optionally, is not less than about 1,700 gmf/in.sup.2. In further
aspects, the shear force can be up to about 4,400 gmf/in.sup.2, or
more. Alternatively, the shear force is not more than about 3,900
gmf/in.sup.2, and optionally is not more than about 3,500
gmf/in.sup.2 to provide improved performance.
[0054] Depending upon the specific design and end use, the
engagement force between a given male component and a given female
component may be adjustable. This adjustability may allow for an
enhanced engagement force during wear and a reduced engagement
force during removal. The adjustability of engagement force may be
linked to an amount that a hook material has been stretched. For
example, the engagement force may be increased or reduced for a
stretched hook material compared to the same hook material in an
unstretched condition.
[0055] When comparing engagement force between stretched hook
materials, forces must be normalized to an unstretched condition.
For example, by stretching a hook material 25%, the number of hooks
per square inch is reduced to 0.8 times (1/[(100+25)/100])=0.8) the
number of hooks as compared to the unstretched hook material. This
reduction in hooks per square inch will reduce the engagement force
per square inch by 0.8 times, but will demonstrate equivalent
normalized engagement force as measured by the included test
method. Additionally, comparisons are made by joining hook material
in a stretched state to loop material and then testing for
engagement force, as compared to joining hook and loop material and
then stretching. It is believed that physical manipulation of a
joined hook and loop system may vary the engagement force.
[0056] An increase in engagement force may be desired in a
stretched state. For example, when a caregiver dons a product on a
child very loosely (in a minimally stretched condition) a first
level of engagement force is desired. However, if the caregiver
dons the same product on the same child more tightly (in a highly
stretched condition) for example immediately before play time, an
increased level of engagement is desired.
[0057] Alternatively, a decrease in engagement force may be desired
in a stretched state. Many caregivers remove the product by pulling
or elongating the hook material as they remove the product from the
user. In these conditions, it may be advantageous for the hook to
reduce engagement force as the caregiver is removing or elongating
the hook material. In this situation a "high" level of engagement
is attained during use, and a relatively "lower" level of
engagement is attained during removal. This allows for easier
removal, as well as less damage to the loop material for a given
level of in use engagement force.
[0058] Fastening systems may include a female component and a male
component having a plurality of hook elements. The male component
may be adapted for releasable engagement with the female component.
Further, the fastening system may have a first normalized peak
shear force to disengage the female component from the male
component when the male component is stretched 0%. The fastening
system may have a second normalized peak shear force to disengage
the female component from the male component when the male
component is stretched 10%. The first normalized peak shear force
may be at least 10% greater than the second normalized peak shear
force. Alternatively, the first normalized peak shear force may be
at least 20% greater than the second normalized peak shear force.
Alternatively, the first normalized peak shear force may be at
least 33% greater than the second normalized peak shear force. The
engagement force in this fastening system decreases as the male
component is stretched.
[0059] A portion of the male component of the fastening system may
be stretchable at least 10% when loaded at 250 g/in. Alternatively,
a portion of the male component of the fastening system may be
stretchable at least 15% when loaded at 250 g/in. A portion of the
male component of the fastening system may be elastic.
[0060] FIGS. 3A and B illustrate a prophetic example of a first
hook material that displays a reduction in engagement force upon
stretching. FIG. 3A illustrates a side view of a first hook
material in an unstretched condition, and FIG. 3B illustrates a
side view of the hook material of FIG. 3A after stretching. The
hook material illustrated in FIG. 3A includes a plurality of hook
elements having have a stem (80) and a cap (82). Further, the cap
defines a characteristic cap angle (84). The cap angle (84) is the
smallest angle a tangent to the bottom side of the cap (82) makes
to perpendicular. The average cap angle (84) is the average of all
the cap angles (84) of the individual hooks that make up the hook
material. Theoretically a smaller cap angle (84) provides greater
engagement force. FIG. 3A illustrates a hook material in an
unstretched (0%) state, having a first average cap angle. FIG. 3B
illustrates a hook material in a stretched (for example 10%) state,
having a second average cap angle. The second average cap angle
(84) is greater than the first average cap angle (84). This
theoretical hook material would have a greater normalized peak
shear force in the unstretched state than in the stretched
state.
[0061] Many different designs may be utilized to achieve a
reduction in engagement force and or an increase in cap angle (84).
The cap angle (84) may be increased by designing the hook material
such that when a stretching force is applied, the force is
transferred to the individual hooks, which in turn deform. The
deformation of the hooks may be tailored, for example, by only
deforming a fraction of the hooks in the hook material, or by
changing the amount of deformation the hooks undergo upon a given
amount of stretching of the hook material. This change may be
effected by the choice of materials, the specific thickness of the
materials, the physical structure of the individual hooks, and
further by the composition or structure of the base or support
material.
[0062] FIGS. 3A and B illustrate a side view of a first hook
material in an unstretched condition and a stretched condition. One
method by which the material stretches is by deformation of the
hook elements. The hook elements, and more specifically, the caps
(82) open, thereby creating a lower engagement force. FIGS. 4A and
B illustrate a side view of a second hook material in an
unstretched condition and a stretched condition. This material
demonstrates a second design where the hook elements may deform
when the material is stretched. The hook elements, and more
specifically, the caps (82) open, thereby creating a lower
engagement force.
[0063] The hook material may be designed such that the average cap
angle (84) of the material after stretching 10% may be at least 20
degrees greater than the average cap angle when the material is
unstretched. Alternatively, the hook material may be designed such
that the average cap angle (84) of the material after stretching
10% may be at least 40 degrees greater than the average cap angle
when the material is unstretched.
[0064] The fastening system may be designed such that the
normalized peak shear force of the unstretched material may be at
least 10% greater than the normalized peak shear force of the
material after stretching 10%. Alternatively, the fastening system
may be designed such that the normalized peak shear force of the
unstretched material may be at least 25% greater than the
normalized peak shear force of the material after stretching
10%.
[0065] An increase in engagement force may be desired in a
stretched state, for example, in situations where the caregiver
anticipates a need for a higher or lower amount of engagement
force. FIGS. 5A and 6A illustrate examples of hook material in an
unstretched state, where stretching may increase the engagement
force by a decrease in cap angle (84). FIGS. 5A and 6A illustrate a
male component of a fastening system including a plurality of hook
elements. The male component may be adapted for releasable
engagement with a female component of the fastening system. The
fastening system may have a first normalized peak shear force to
disengage the female component from the male component when the
male component is stretched 0%. The fastening system may have a
second normalized peak shear force to disengage the female
component from the male component when the male component is
stretched 10%. The first normalized peak shear force may be at
least 10% less than the second normalized peak shear force.
Further, depending upon the desired end use, the first normalized
peak shear force may be at least 20% less than the second
normalized peak shear force.
[0066] FIGS. 5A and B illustrate a prophetic example of a first
hook material that displays an increase in engagement force upon
stretching. FIG. 5A illustrates a side view of a first hook
material in an unstretched condition, and FIG. 5B illustrates a
side view of the hook material of FIG. 5A after stretching. The
hook material illustrated in FIG. 5A includes a plurality of hook
elements having a stem (80) and a cap (82). Further, the cap
defines a characteristic cap angle (84). FIG. 5A illustrates a hook
material in an unstretched (0%) state, having a first average cap
angle. FIG. 5B illustrates a hook material in a stretched (for
example 10%) state, having a second average cap angle. The second
average cap angle (84) is less than the first average cap angle
(84). This theoretical hook material would have a greater
normalized peak shear force in the stretched state than in the
unstretched state.
[0067] Many different designs may be utilized to achieve an
increase in engagement force and or a decrease in cap angle (84).
The cap angle (84) may be decreased by designing the hook material
such that when a stretching force is applied, the force is
transferred to the individual hooks, which in turn, deforms the
individual hooks. The deformation of the hooks may be tailored, for
example, by only deforming a fraction of the hooks in the hook
material, or by changing the amount of deformation the hooks
undergo upon a given amount of stretching of the hook material.
This change may be effected by the choice of materials, the
specific thickness of the materials, the physical structure of the
individual hooks, and further by the composition or structure of
the base or support material.
[0068] FIGS. 5A and B illustrate a side view of a first hook
material in an unstretched condition and a stretched condition. One
method by which the material stretches, is by deformation of the
hook elements. The hook elements, and more specifically, the caps
(82) may be reoriented to capture and hold loop material more
securely, thereby creating a higher engagement force. FIGS. 6A and
B illustrate a side view of a second hook material in an
unstretched condition and a stretched condition. This material
demonstrates a second design where the hooks elements may deform
when the material is stretched. The hook elements, and more
specifically the caps (82) are reoriented to capture and hold loop
material more securely, thereby creating a greater engagement
force.
[0069] The hook material may be designed such that the average cap
angle of the material after stretching 10% may be at least 20
degrees less than the average cap angle when the material is
unstretched. Alternatively, the hook material may be designed such
that the average cap angle of the material after stretching 10% may
be at least 40 degrees less than the average cap angle when the
material is unstretched. The average cap angle (84) may be at least
90 degrees when the material is unstretched.
[0070] The shear strength of a mechanical fastening system can be
determined in accordance with the following method.
[0071] Test Method: Shear Strength
[0072] Test Procedure
[0073] This procedure is a tensile bench test to measure the shear
force required to separate a mechanical fastening system that joins
two materials. The shear force of separation is measured by
determining load values as the two materials are pulled apart
parallel to their plane of contact. The shear strength test values
are an indication of how well the mechanical fastening system stays
engaged against in-plane shear force. The sample is pulled in the
tensile tester until the sample pulls apart. Shear strength is the
peak load result. Shear strength may be normalized by dividing the
peak load by the contact area at 0% stretch resulting in a force
per normalized area.
[0074] 1. Overview
[0075] A material sample of two material layers joined by a
mechanical fastening system such as a hook and loop system is
assembled. The fastening system joins two pieces of material that
overlap in the landing area. The sample is prepared by aligning and
applying the loop material to the stabilized hook material, and by
rolling a 4.5 lb. (2.04 kg) mechanical roller over the fastening
system to engage the fastener. The sample is then placed between
clamps on a tensile tester. One piece of material is held in the
upper clamp, while the other is held in the lower clamp. The
fastening system is arrayed between the clamps, approximately
parallel to the edges of the clamp faces. The width of the hook
material is 13 mm, the width of the loop material is approximately
64 mm, and the hook overlaps the loop 50 mm in the lengthwise
direction (at 0% stretch). The gauge length is 3 inches (76 mm)
between the edges of the clamp faces. The term "load" refers to the
gram value measured by the load cells in the tensile tester.
[0076] The jaws are separated at a controlled rate of 12 inch/min
(305 mm/min) until the fastening system is pulled apart. The load
values generated on the material throughout this process are
recorded. The load as a function of elongation is recorded on a
computer.
[0077] Load values for samples of non-standard widths and lengths
should be normalized by multiplying or dividing by the factor by
which the sample overlap area deviates from 13 mm by 50 mm. For
example, the peak load value derived by pulling apart a 1 inch
(25.4 mm) wide by 50 mm long sample should be multiplied by
13/25.4.
[0078] Suitable materials comprise hook and loop fastening systems,
which may comprise or be attached to materials used to form the
disposable garments described herein.
[0079] 2. Apparatus and Materials [0080] 2.1 Constant Rate of
Extension (CRE) tensile tester such as an MTS tensile tester model
Sintech 1/G; available from MTS Systems Corporation, located at
1400 Technology Drive, Eden Prairie, Minn., USA. [0081] 2.2 Load
cells: A suitable cell selected so the majority of the peak load
values fall between 10% and 90% of the manufacturer's recommended
ranges of load cell's full scale value; for example, Model 100N
available from MTS Systems Corporation, located at 1400 Technology
Drive, Eden Prairie, Minn., USA. [0082] 2.3 Operating software and
data acquisition system such as MTS TestWorks.RTM. for Windows
software version 3.10; available from MTS Systems Corporation,
located at 1400 Technology Drive, Eden Prairie, Minn., USA. [0083]
2.4 Grips: pneumatic-action grips, top and bottom, identified as
part number 38.00716 available from MTS Systems Corporation. [0084]
2.5 Grip faces: 25 by 75-mm (1 by 3-inch) interlocking faces such
as are available from MTS Systems Corporation. [0085] 2.6 Roller:
4.5 lb (2.04 kg) mechanical roller available from Chemsultants
International, Mentor, Ohio, USA. [0086] 2.7 Plexiglas,
1/4''.times.4''.times.4''
[0087] 3. Conditioning
[0088] Reasonable ambient conditions are required for testing. The
instruments used should be calibrated as described in the
manufacturer's instructions for each instrument.
[0089] 4. Test Specimen (Illustrated in FIG. 5)
[0090] The hook material sample (102) having an unstretched width
of 13 mm and an unstretched length of 50 mm is adhered to a piece
of rigid material, for example a piece of Plexiglas (110). The
material may be adhered to the Plexiglas in an unstretched state,
such that the dimensions of the hook material are 13 mm by 50 mm.
Alternatively, the material may be adhered to the Plexiglas in a
stretched state, for example such that the dimensions of the hook
material are 13 mm by 55 mm (stretched 10%). This method normalizes
the attachment strengths for the stretch of the material. When
testing material samples taken from absorbent articles, the
dimensions of the hook material (102) and the loop material (101)
may be adjusted. Results should be normalized for the size of
overlap tested.
[0091] The loop material sample (101) is cut to have a width (a) of
approximately 2.5 in. (64 mm) and a length (b) of approximately 4
in. (102 mm). The loop sample (101) is placed onto the hook
material sample (102) such that the loop material sample (101)
completely overlaps (c) the hook material sample (102),
perpendicular from the 64 mm wide edge, centered on the 64 mm. The
joined materials should not be handled or pressed.
[0092] The specimen is placed on a hard flat surface, and the test
sample is then pressed down with a standard 4.5 lb (2.04 kg)
mechanical roller by rolling the roller across the hook/loop
engagement area back and forth in the length direction on the loop
material sample (101) one time. The centerline of the sample should
be aligned with the centerline of the face of the roller.
[0093] The specimen is tested using the tensile test procedure that
follows. At least four specimens of each sample should be tested,
and the results averaged.
[0094] 5. Procedure
Tensile Tester Test Conditions
TABLE-US-00001 [0095] Preload No Test speed 305 mm/min Gauge length
(h): 3 inches (76 mm) Number of cycles: 1
[0096] A. Using the tensile frame pushbutton controls for crosshead
position, move grips to provide a gauge length (h) of 3 inches (76
mm). Tare the crosshead channel to this initial gauge length.
[0097] B. Without touching the fastening area, hold a material
specimen so that the hook material is up and the loop material is
down. Place the Plexiglas onto which the hook is adhered in the
upper jaw (103) of the tester. Place the hook material in the upper
jaw (103) such that it is centered in the horizontal direction,
with the loop material extending below the center of the upper jaw
(103). [0098] C. Close the upper jaw (103) on the specimen and tare
the load channel. [0099] D. Hold the specimen in such a way as to
minimize slack in the specimen, but do not place the specimen under
tension, and close the lower jaw (104) on the loop material. [0100]
E. Run the test using the above parameters by clicking on the RUN
button. [0101] F. When the test is complete, save the data to a
sample file. [0102] G. Remove the specimen from the jaws (103,
104). [0103] H. Run additional specimens of a given sample using
steps B-G; the data for all specimens should be saved to a single
file. [0104] I. Continue testing all samples in this manner. [0105]
J. Data are reported as the peak load and the total energy under
the load-extension curve.
[0106] Having described the invention in rather full detail, it
will be readily apparent that various changes and modifications can
be made without departing from the spirit of the invention. All of
such changes and modifications are contemplated as being within the
scope of the invention as defined by the subjoined claims.
* * * * *