Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CREPED HYDROENTANGLED
NONWOVEN LAMINATE AND
~ 5 PROCESS FOR MAKING
FIELD OF INVENTION
The present invention is directed to a nonwoven laminate material suitable for use as a
loop f~leni"g ",alt:rial for mechanical fastening systems, commonly referred to as hook and
loop fastener systems. More specifically, this invention relates to a nonwoven laminate having
a creped hydroentangled nonwoven layer attached to a support layer which, when used as a
loop raslening material, engages the hooks of a complementary hook material.
BACKGROUND OF THE INVENTION
Mechanical fastening systems, of the type otherwise referred to as hook and loopfastener systems, have become increasingly widely used in various consumer and industrial
20 applicalions. A few examples of such applicdlions include disposable personal care absorbent
articles, clothing, sporting goods equipment, and a wide variety of other miscellaneous articles.
Typically, such hook and loop fastening systems are employed in situations where a
reraslenable connection between two or more materials or articles is desired. These
mechanical fastening systems have in many cases replaced other conventional devices used
25 for making such refastenable connections, such as buttons, buckles, zippers, and the like.
Mechal1ical fastening systems typically employ hvo components -- a male (hook)
component and a female (loop) component. The hook component usually includes a plurality
of semi-rigid, hook-shaped elements anchored or connected to a base material. The loop
30 component generally includes a resilient backing material from which a plurality of upstanding
loops project. The hook-shaped elements of the hook component are designed to engage the
loops of the loop material, thereby forming mechanical bonds between the hook and loop
elements of the t~,vo components. These mechanical bonds function to prevent separation of
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the respective components during normal use. Such mechanical fastening systems are
designed to avoid separation of the hook and loop components by application of a shear force
or stress, which is applied in a plane parallel to or defined by the connected surfaces of the
hook and loop components, as well as certain peel forces or stresses. However, applicd~ion of
5 a peeling force in a direction generally perpendicular or normal to the plane defined by the
connected surfaces of the hook and loop components can cause separation of the hook
elements from the ioop elements, for example, by breaking the loop elements and thereby
releasing the engaged hook elements, or by bending the resilient hook elements until the hook
elements disengage the loop elements.
~0
Mechanical fastening systems can be advantageously empioyed in disposable personal
care absorbent articles, such as disposable diapers, disposable garments, disposable
incontinence products, and the like. Such disposable products generally are single-use items
which are discarded after a relatively short period of use -- usually a period of hours -- and are
15 not intended to be washed and reused. As a result, it is desirable to avoid expensive
components in the design of such products. Thus, to the extent that the hook and loop
co" ,ponents are employed in such products, the hook and loop components need to be
relatively inexpensive in terms of both the materials used and the manufacturing processes for
making these components. On the other hand, the hook and loop components must have
20 sufficient structural integrity and resiliency to withstand the forces applied thereto during
normal wear of the absorbent article, in order to avoid potentially embarrassing situations for
the wearer that can result from premature separation or disengagement of the hook and loop
components.
U.S. Pat. No. 4,761,318 to Ott et al. discloses a loop fastening material useful in a
mechanical fastening system for disposable articles. The loop fastening material disclosed by
this patent includes a fibrous layer having a plurality of loops on a first surface adapted to be
releasably engaged by a mating hook fastener portion and a layer of thermoplastic resin
adhered to a second surface of the fibrous structure opposite the first sur~ace. The
thermoplastic resin anchors the loops in the fibrous structure.
U.S. Pat. No. 5,032,122 to Noel et al. discloses a loop fastening material useful in a
mechanical fastening system for a disposable article. The loop fastening material disclosed by
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this patent includes a backing of orientable material and a multiplicity of fibrous elements
extending from the backing The fibrous elements are formed by continuous filaments
positioned on and intermittently secured to the backing when the orientable material of the
bachin~ is in its dimensionally ~ state. The fibrous elements are formed by the shirring
~ 5 of the filaments between spaced, fixed regions of securement to the backing when the
orientable material is caused to be transformed to its dimensionally stable state such that it is
caused to conl,~ or gather along its path of response. Thus, the loop rllaterial of this patent
requires a backing of orienlable material, such as an elastic or elastomeric or heat shrinkable
material, that is caused to be transformed from a dimensionally stable state to a dimensionally
10 unstable state and returned it to its dimensionally stable state.
U.S. Pat. No. 5,326,612 to Goulait disr~Qses another a loop fastening material useful in
a mechanical fastening system for a disposable article. The loop fastening material disclosed
by this patent includes a nonwoven web secured to a backing. The nonwoven web serves to
1~ admit and entangle the hooks of a complementary hook component. The nonwoven web has a
specified basis weight range of between about 5 to about 42 g/m2, an inter-fiber bond area of
less than about 10 percent, and a total plan view bonded area of less than about 3~ percent.
Notwithstanding the teachings of the aforementioned references, the need nonetheless
20 exists for an improved loop fastening material for a mechanical fastening system, particularly
as such are used in d;sposable personal care absorbent articles. The creped hydroentangled
nonwoven laminate loop fastening materiai of the present invention is soft and cloth-like, and
therefore, aesthetically appealing in terms of appearance and feel. The loop material of the
present invention is relatively inexpensive to produce, especially in comparison to conventional
2~ loop materials formed by knitting, warp knitting, weaving, and the like, yet exhibits comparable
and/or improved peel and shear strengths as compared to conventional loop fastening
lerials when used with commercially available hook fastener materials.
S~JMMARY OF THE INVENTION
The present invention is directed to a hydroentangled nonwoven laminate materialsuitable for use as an improved loop fastening material for hook and loop fastening systems.
The creped hydroentangled nonwoven laminate material of this invention has a three-
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dimensional surface topography particulariy suitable ~or receiving and engaging hook elemenls
of a col"rlen,entary hook material. The hook material can be any of a wide variety of
commercially available hook components which, as is known in the art, typically include a base
mal~rial from which a plurality of hook elements project.
The creped hydroentangled nonwoven Idl~ ~ale loop material of the present invention
includes a creped hydroentangled nonwoven layer attached to a support layer. The creped
hydroentangled nonwoven layer may be, for example, a spunbond nonwoven web or a staple
fiber bonded carded web. The support layer may be formed of any material that can be
10 suitably attached or bonded to the hydroentangled nonwoven layer, including a plastic film or
another nonwoven web. The exposed, top surface of the creped hydroentangled nonwoven
layer includes raised "loop" areas having low fiber density and high z-directional fiber
orientation that are designed to receive and engage the hook elements projecting from a hool<
material. The raised areas of the creped nonwoven layer are separated by non-raised areas
15 having relatively higher fiber density and relatively lower z-directional fiber orientation when
compared to the fiber density and z-directional fiber orientation of the raised areas. The
primary areas of bonding or ~llach~enl of the fibers or filaments forming the nonwoven layer
to the top surface of the underlying support layer are the non-raised areas; in addition, some
secondary bonding of the fibers or filaments of the nonwoven layer to the support layer outside
20 of the non-raised areas may exist. The support layer provides structural integrity for the creped
hydroenlall5Jled nonwoven laminate materiai and dimensionally sl~ t?s the crepednonwoven layer. The creped structure of the hydroentangled nonwoven layer further provides
l~sislance against compression of the fibers forming the hook receiving loop material during
use, thereby fac;lilali"g entry and engagement of hook elements projecting from the hook
25 material.
Hydroentangling of the nonwoven layer, which is performed prior to creping of the
nonwoven layer, physically alters the fibrous structure of the nonwoven layer. This hydraulic jet
process rearranges and opens the fibers or filaments forming the nonwoven layer. Creped
30 hydroentangled nonwoven loop laminates made in accordance with the present invention have
shown a surprising improvement in peel and shear strength properties over non-creped
hydroenlan~,!ed nonwoven loop la" ,inales. The creped hydroentangled nonwoven loop
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laminate of this invention can be employed as the loop material of a hook and loop fastening
system, such as used on disposable personal care absorbent articles.
A suitable process for forming the creped hydroentangled nonwoven laminate loop
5 material of this invention includes: providing a nonwoven layer, hydroentangling said
nonwoven layer, providing a support layer, providing opposedly positioned first and second
heated ~ nder rolls defining a nip therebetween, said first roll having a patterned outermost
surface and said second roll having a flat oule:r,nosl surface, rotating said first and second rolls
in opposite directions, said first roll having a first rotational speed and said second roll having a
10 second rotational speed, said second rotational speed being 2 to 8 times greater than said first
rotational speed, and passing the hydroentangled nonwoven layer and support layer within the
nip formed by said first and second counter-rotating rolls to form a creped hydroentangled
nonwoven lar"i"dle. As a result of this forming process, the basis weight of the hydroentangled
nonwoven layer is increased from a first basis weight prior to being creped and laminated to a
15 second, higher basis weight after it exits the nip formed by the counter-rotating pattern and
anvil rolls.
When used as the loop component of a hook and loop fastening system for a
disposable personal care absorbent article, the creped hydroentangled nonwoven laminate
20 loop ",alerial of this invention can be bonded or attached to the outer layer or backsheet of the
article as a discrete patch of loop material. Altematively, the creped hydroentangled nonwoven
laminate loop material can form the entire outer cover or backsheet of such a disposable
personal care absorbent article.
25 BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the loop material of the present invention.
FIG. 2 is a cross-sectional side view of the loop material of FIG. 1.
FIG. 3 is a perspective view of a hook material engaged with the loop material of FIG.
1.
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FIG. 4 is a cross-sectional side view of the hook and loop materials shown in FIG. 3.
FIG. 5A is a magnified (10x) photograph of a creped non-hydroentangled nonwoven
layer of a creped nonwoven laminate loop material.
FIG 5B is a magnified (10x) photograph of a creped h~,d~uenlan~e~ nonwoven layer of
the creped hydroentangled nonwoven laminate loop material of the present invention.
FIG. 6 is a perspective view of a disposable diaper with the loop material of the present
10 invention as a loop patch.
FIG. 7 is a schematic side view of a process and appa,~Lus for making the loop
material of the present invention.
FIG. 3 is a partial perspective view of a pattern roll that can be used in accordance with
the process and appardlus of FIG. 7.
FIG. 9 is a schematic side view of an ext:r,lplary process and apparatus for producing a
nonwoven web of spunbonded filaments.
FIG 10 is a schematic view of an exemplary process and appar~lus for forming a
hydroentangled nonwoven web.
DETAILED DESCRIPTION OF THE INVENTION
2~
The present invention relates to a creped hydroentangled nonwoven laminate material
suitable for use as an improved loop rasleni"g material for a mechanical or hook and loop
~aslen 1g system. For purposes of illustration only, the present invention will be described as a
loop faslen 1g material both separately and in conjunction with its use with disposable personal
30 care absorbent articles, which include diapers, training pants, incontinence garments, sanitary
napkins, bandages and the like. As such, the invention should not be limited to these specific
uses, as it is instead intended that the present invention be used in all applications in which
such creped hydroenLang:cd nonwoven laminate material can be employed.
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The loop r~alenal of the present invention is intended to be utilized with a wide variety of
hook materials. Exemplary of hook materials suitable for use with the loop material of the
present invention are those obtained from: Velcro Group Company, of Manchester, New
Hampshire, under the trade designations CFM-22-1097; CFM-22-1121; CFM-22-1162;
CFM-25-1003; CFM-29-1003; and CFM-29-100~; or Minnesota Mining & Manufacturing Co., of
St. Paul, Minnesota, under the desi~ ion CS 200. Suitable hook materials generally
cGn.prise from about 16 to about 620 hooks per square centimeter, or from about 124 to about
388 hooks per square centimeter, or from about 155 to about 310 hooks per square10 centimeter. The hooks suitably have a height of from about 0.00254 centimeter (cm) to about
0.19 centimeter, or from about 0.0381 centimeter to about 0.0762 centimeter.
As can be seen in FIGS. 3 and 4, the hook material 22 includes a base layer 24 with a
pluraiity of bi-directional hook elements 26 extending generally perpendicularly therefrom. As
15 used herein, the term "bi-directional" refers to a hook material having individual adjacent hook
elements oriented in opposite directions in the machine direction of the hook material. The
term "uni-directional," on the other hand, refers to a hook material having individual adjacent
hook elements oriented in the same direction in the machine direction of the hook material.
In order to achieve constant data regarding the present invention, a single type of hook
material was used in evaiuating the loop material of the present invention. The hook elements
26 have an average overall height H measured from the top surface 25 of the base material 24
to the highest point on the hook elements 26. The average height of the hook elements 26
used in conjunction with the present invention is about 0.5 millimeter (mm). Hook material 22
25 has a hook density of about 265 hooks per square centimeter. The thickness of base material
24 is about 3.5 mils. The hook material 22 used in conjunction with the present invention is
available from Velcro USA as CFM-29-1003. Other dimensions and properties of the hook
material 22 are as outlined in the examples described hereinbelow.
Although the term "hook materiall' is used herein to designate the portion of a
mechal1ical fastening system having engaging (hook) elements, it is not intended to limit the
form of the engaging elements to only include "hooks" but shall encompass any form or shape
of engaging element, whether uni-directional or bi-directional, as is known in the art to be
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designed or adapted to engage a complementary loop fastening material, such as the creped
hydroentangled nonwoven laminate material of the present invention.
Rerer,ing to FIGS. 1 and 2, an embodiment of the creped hydroentangled nonwoven
la" ~ ,ale loop material 10 of the present invention is illustrated. By way of definition, the term
"creped hydroentangled nonwoven laminate loop material" as used herein is intended to refer
to a loop or female colnponent for a hook and loop rasteni.~g system that comprises, in its
si"~rlest form, a creped hydroentangled nonwoven layer or web secured to a support layer or
web. This term is not intended to limit the loop malerial of the present invention to only
10 nonwoven materials; rather, the loop material of the present invention also includes alternative
embodi",enls in which, for example, the support layer or web is not a nonwoven layer or web,
as will described hereinbelow. Nor is use of the term "loop" intended to limit the loop material of
the present invention to only materials in which discrete, separately formed loops of material
are employed to receive and engage the hook elements of a complementary hook material;
15 rather, the loop material of the present invention includes fibrous nonwoven layers in which the
individual fibers function to engage the hook elements without such fibers being formed into
disc,~le loops.
As used herein, the terms "layer" or "web" when used in the singular can have the dual
20 meaning of a single element or a plurality of elements. As used herein, the term "laminate"
means a cor"posite material made from two or more layers or webs of material which have
been attached or bonded to one another.
Referring again to FIGS. 1 and 2, loop material 10 is shown comprising a creped
25 hydroentangled nonwoven layer 12 bonded to a support layer 14. Nonwoven layer 12 can be
generally described as any nonwoven web that, when formed in accordance with the present
invention, is suitable for receiving and engaging the hooks of a complementary hook material.
As used herein, the terms "nonwoven layer" or "nonwoven web" mean a web having astructure of individual fibers or threads which are interlaid, but not in an identifiable manner as
30 in a knitted fabric. Commercially availabie thermoplastic polymeric materials can be
advantageously employed in making the fibers or filaments from which nonwoven layer 12 is
formed. As used herein, the term "polymer" shall include, but is not limited to, homopolymers,
copolymers, such as, for example, block, graft, random and alternating copolymers,
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terpolymers, etc., and blends and mo~liricalions thereof. Moreover, unless otherwise
specifically limited, the term "polymer" shall include all possible geometrical configurations of
the ",aterial, including, without ' "ilalion, iso~dcl;c, syndiotactic and random symmetries. As
used herein, the terms "thermoplastic polymer" or "thermoplastic polymeric material" refer to a
5 long-chain polymer that softens when exposed to heat and returns to its original state when
cooled to ambient temperature. Exemplary thermoplastic materials include, without limitation,
polyvinyl chlorides, polyesters, polyamides, polyfluorocarbons, polyolefins, polyurethanes,
polystyrenes, polyvinyl alcohols, caprolactams, and copolymers of the foregoing. ~he fibers
used in making nonwoven layer 12 may have any sll ' le Illo,,uhology and may include hollow
10 or solid fibers, straight or crimped fibers, bicomponent, multicomponent, biconstituent or
multiconstituent fibers, and blends or mixes of such fibers, as are well known in the art.
Nonwoven webs that can be employed as nonwoven layer 12 of the present inventioncan be formed by a variety of known forming processes, including spunbonding, airlaying, or
15 bonded carded web formation processes. Spunbond nonwoven webs are made from melt-
spun filaments. As used herein, the term "melt-spun filaments" refers to small diameter fibers
and/or filaments which are formed by extruding a molten thermoplastic material as filaments
from a plurality of fine, usually circular, capillaries of a spinnerette with the diameter of the
extruded rildme~ i then being rapidly reduced, for example, by non-eductive or eductive fluid-
20 drawing or other well known spunbonding mechanisms. The production of spunbondnonwoven webs is described in U.S. Pat No. 4,340,563 to Appel et al., U.S. Pat. No.
3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos.
3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartmann, U.S. Pat. No.
3,276,944 to Levy, U.S. Pat. No. 3,502,538 to Peterson, and U.S. Pat. No. 3,542,615 to Dobo
25 et al., all of which are incorporated herein by reference. ~he melt-spun filaments formed by the
spunbond process are generally continuous and have diameters larger than 7 microns, more
particularly, between about 10 and 20 microns.
In making the specific embodiment of the present invention shown in FIGS. 1 and 2, a
30 conventional spunbond process may be used to form a nonwoven web of melt-spun filamenls
formed from an extrudable thermoplastic resin which contains about 80 percent, by weight, of
polypropylene homopolymer, and about 20 percent, by weight, of Montell USA CatalloyTM
KS084 or other heterophasic polymer composition such as described in U.S. Patent 5,368,927
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to Lesca et al., the disclosure of which is incorporated herein by reference. In addition,
extrudable thermoplastic resins of a random copolymer of propylene and ethylene, such as a
random copolymer containing from about 0.5 to about 10 percent, by weight, ethylene and
from about 99.5 to about 90 percent, by weight, propylene are considered suitable for forming
5 the hydroentangled nonwoven layer of the present invention.
A su"-''e spunbond process and appa,al-ls for producing a nonwoven web of melt-
spun rila~"enls are schen,alically illustrated in FIG. 9. In forming such a spunbond web of melt-
spun filaments (e.g., spunbonded filan~enls), pellets, chips or the like of a polymeric material
are introduced into a pellet hopper 80 of an extruder 82. The extruder 82 has an extrusion
screw (not shown) that is driven by a conventional drive motor (not shown). As the polymer
advances through the extruder 82, due to rotation of the extrusion screw by the drive motor,
the polymer is progressively heated to a molten state. Heating of the polymer to the molten
state may be accomplished in a plurality of discrete steps with its temperature being gradually
15 elevated as it advances through discrete heating zones of the extruder 82 toward an extrusion
die 84. The die 84 may be yet another heating zone where the temperature of the polymer is
"lainlai"ed at an elevated level for extrusion. The temperature which will be required to heat
the polymer to a molten state will vary somewhat depending upon the type of polymer used.
Heating of the various zones of the extruder 82 and the extrusion die 84 may be achieved by
20 any of a variety of conventional heating arrangements (not shown).
The filaments of the molten polymer are initially formed and discharged in a stream 86
from spaced-apart filament forming means 88. The forming means 88 may be any suitable
filament forming means, such as spinnerettes, die orifices, or similar equipment associated
25 with melt-spinning processes such as, for example, the spunbonding process. The melt-spun
filaments discharged from the forming means 88 are drawn through passage 85 in fiber draw
unit 87, to which high speed fluid sources 89, such as jet streams of air, are operatively
connected. The action of the high speed fluid on the melt-spun filaments 86 passing
downwardly through passage 85 stretches the melt-spun filaments 86, and increases the
30 speed of delivery of the melt-spun filaments to a forming surface. The melt-spun rilamenLs
upon exiting passage 85 are deposited in a random manner on a foraminous forming sur~ace
90, generally assisted by a vacuum device (not shown) placed underneath the forming surface
90. The melt-spun filaments are between 1.5 and 5.0 denier per filament (dpf), and more
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particularly between 2.0 and 2.5 dpf. The purpose of the vacuum is to eliminate the
undesirable scattering of the filaments and to guide the filaments onto the forming surface 9~
to form a nonwoven web 92 of melt-spun polymer filaments. The forming surface 90 is
supported in turn on roller 94 driven by convenlional drive means (not shown).
The nonwoven web 92 separates from the forming surface 90, and is directed into and
~ through nip 96 of a patterned roller arrangement 100. The pattern roll 98 is used for thermal
bonding of the web 92. The smooth anvil roll 99, together with the pattem roll 98, defines a
thermal pattern bonding nip 96. Alternatively, anvil roll 99 also may bear a bonding pattern on
10 its outer surface. The pattem roll 98 is heated to a suitable bonding temperature by heating
means (not shown) and is rotated by conventional drive means (not shown), so that when the
web 92 passes through nip 96, a series of thermal pattem bonds is formed. Nip pressure
within nip 96 should be sufficient to achieve the desired degree of bonding of web 92, given
the line speed, bonding temperature and materials forming web 92. For example, nip
15 pressures within the range of about 60 to 85 pounds per lineal inch (pli) (about 1.07 to 1.51
kilograms per lineal millimeter) are suitable. As a result of the thermal pattem bonding, the web
92 of filaments becomes a pattern bonded web 102 of enhanced stability.
The percent bond area of the pattem bonded web 102 is important to the functionality
20 of the creped hydroentangled nonwoven laminate loop material of this invention. Generally
speaking, the percent bond area of the nonwoven web should be s~rri~,ienlly high so that a
majority of the generally continuous melt-spun filaments have portions that extend through at
least two pattern bonds. In this way, individual filaments within the nonwoven web can mor
securely engage the hook elements of a hook material, resulting in suitable peel and shear
25 strength properties for the loop material. In addition, a sufficiently high percent bond area
serves to reduce fiber pull-out, which can result from repeated disengagement of hook
elements from the loop ""3le(ial. A high incidence of fiber pull-out can reduce the peel and/or
shear strength of the loop material, and deleteriously affect the appearance (i.e., increased
fuzziness) of the loop material. Thus, increasing the percent bond area tends to improve the
30 surface integrity and durability of the loop material. On the other hand, the percent bond area
should not be so high that the number and size of inter-filament areas in which the hook
elements of the hook material are received when engaging the loop material are insufficiently
large to allow a sufficient number of hook elements to be received into the loop material. For
11
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example, in the spunbond apparatus illustrated in FIG. 9, the pattern roll 98 has a point bond
pattern with a surface bond area between about 10 percent and about 25 percent or more,
using a bond point density of between about 15.5 and 46.5 bond points per square centimeter.
Altematively, a pattern roll 98 having a surface bond area within the range of about 13 percent
to about 22 percent, or within the range of about 15 percent to about 20 percent, has been
found s~ 'le for use in the present invention. Bond densities above and below the above-
stated range also can be used, with the specific bond density being dependent upon the size
of the individual bond points. The pattern bonded web 102 then is passed to other process
and/or treatment steps.
The inventors consider hydroentangling to permit use in the present invention ofnonwoven webs having relatively higher percent bond areas, such as, for example, more than
25%, when compared with non-hydraulically entangled nonwoven webs, as the
hydroentangling process redistributes and opens the fibers or filaments of the nonwoven web.
15 Thus, nonwoven webs having higher percent bond areas, and consequently, reduced
incidence of fiber pull-out and improved surface integrity and durability, can be employed as
the nonwoven layer of the creped hydroentangled nonwoven laminate loop material, since the
number and size of inter-filament areas in the hydroentangled nonwoven web for receiving and
engaging hook elements of a complementary hook material are not unduly restricted.
Nonwoven layer 12 also may be made from bonded carded webs. Bonded carded
webs are made from staple fibers, which are usually purchased in bales. The bales are placed
in a picker, which separates the fibers. Then, the fibers are sent through a combing or carding
unit, which further breaks apart and aligns the staple fibers in the machine direction to form a
25 generally machine direction-oriented fibrous nonwoven web. Once the web is formed, it then is
bonded by one or more of several known bonding methods. One such bonding method is
powder bonding, wherein a powdered adhesive is distributed through the web and then
activated, usually by heating the web and adhesive with hot air. Another suitable bonding
method is pattern bonding, wherein heated calender rolls or ultrasonic bonding equipment are
30 used to bond the fibers together, usually in a localized bond pattern, though the web can be
bonded across its entire surface if so desired. Another suitable bonding method, particularly
when using bicomponent staple fibers, is through-air bonding.
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Through-air bonders are well known in the art and need not be described in detail
herein. Generally, a common type of through-air bonder includes a perforated roller, which
receives the web, and a hood surrounding the perforated roller. A flow of heated air is directed
from the hood and applied through the web and into the perforated roller. The heated air heats
- 5 the web to a temperature above the melting point of the lower melting point component of the
."ponent filaments, but below the melting point of the higher melting point co",ponent.
Upon heating, the lower melting polymer po~lions of the web filaments melt and adhere to
adJacent filaments at their cross-over points, while the higher melting polymer portions of the
filaments tend to maintain the physical and dimensional integrity of the web. For exa"l~ le,
when polypropylene and polyethylene are used as the polymer components, the air flowing
through the through-air bonder can have a temperature ranging from about 110~ C. to about
140~ C. and a velocity from about 30 to about 150 meters per minute. The dwell time of the
web in the through-air bonder typically should not exceed about 6 seconds. It should be
ullderslood, however, that the parameters of the through-air bonder depend on factors such as
the type of polymers used, the thickness of the web, etc.
Airlaying is another well known process by which fibrous nonwoven layer 12 can be
formed. In the airlaying process, bundles of small fibers having typical lengths ranging from
about 6 to about 19 mitlimeters (mm) are separaled and entrained in an air supply and then
deposited onto a forming screen, usually with the assistance of a vacuum supply. The
randomly deposited fibers then are bonded to one another using, for example, hot air or a
spray adhesive.
In order to obtain the specified range of physical properties in the resultant creped
hydroentangled nonwoven layer 12 in accordance with the present invention, the bonding
process used to bond the fibers or filaments of the nonwoven layer should be a process that
can control the level of compression om--"aFse of the fibrous structure during the formation
process. Whatever forming process is utilized, the degree of bonding will be dependent upon
the fibers/polymers used, but in any event, it is desirable that the amount of web compression
be collllullcd during the heating stage.
After the nonwoven layer is formed, such as pattern bonded web 102 of FtG. 9, the
nonwoven web is passed through a conventional hydroentangling process and apparatus,
13
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such as illustrated in Fig. 10. The nonwoven web may be formed and hydroentangled in a
continuous (in-line) process, that is, hydroentangling takes place on the same foraminous (i.e.,
mesh fabric) surface on which the nonwoven web is formed. Alternatively, the nonwoven web
may be transferred to a different foraminous surface for hydroentangiing. Although
hydroenlang~ g is described herein as a suitable process for providing the redistribution and
rearrangement of fibers or filaments in the nonwoven layer of the creped hydroentangled
nonwoven lami.1dl~ material of this invention, other entangling processes for mechanically
working the nonwoven fibers or filaments, such as stitchbonding, needlepunching or needling,
also may be advantageously employed.
As shown in FIG. 10, the nonwoven layer 102 passes through a conventional
hydroentangling or hydraulic entangling machine 104, which includes one or more hydraulic
entangling manifolds 106. The nonwoven web 102 passing under the hydraulic entangling
manifolds 106 is treated with jets of liquid to rearrange the fibrous structure of the fibers or
1~ filaments forming the nonwoven web 102. Although the inventors should not be held to a
specific theory of operation, it is believed that in rearranging the fibers or filaments forming the
nonwoven web, hydroentangling serves to separate and open the fibers or filaments of the
nonwoven web 102, adding bulk to the fibrous web structure, and thereby enhancing the ability
of hook elements of a complementary hook material to engage the fibrous loop material.
Hydroentangling of nonwoven layer 102 may be accomplished utilizing conventionalhydraulic entangling equipment, such as disrlosed in U.S. Pat. No. 3,485,706 to Evans and
U.S. Pat. No. 5,284,703 to ~verhart et al., both of which are incorporated herein by reference.
The hydroentangling process may be carried out with any appropriate working fluid, such as,
25 for example, water. The working fluid flows through one or more manifolds 106 which evenly
distributes the fluid to a series of individual holes or orifices. The holes or orifices may be from
about 0.003 to about 0.01~ inch (about 0.076 to about 0.38 millimeter) in diameter. For
example, a manifold produced by Honeycomb Systems, Inc. of Biddeford, Maine conla;"s a
single row of aligned holes at 30 holes per inch (12 holes per centimeter), with each hole
30 having a diameter of 0.007 inch (0.18 millimeter). Alternatively, many other manifold
configurations may be used. For example, a single manifold may be used or several manifolds
may be arranged in succession.
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In the hydroentangling process, the working fluid passes through the orifices at a
pressure ranging from about 350 to about 1300 pounds per square inch gage (psig) .(about
2413 to about 8963 kilopAs~ls) to form fluid streams that impact the nonwoven web 102. Fluid
pressure should be surri-.;e"lly high to achieve the desired rearrangement and opening of the
- 5 fibers or filaments of the web, yet not so high as to unduly compact, or d;sintegrate, the
nonwoven web. Other process conditions, such as the line speed and number of manifolds, as
- well as the basis weight of the nonwoven web, can affect the degree of fiber separation
resulting from the hydraulic entanglement process.
As is typical in many water jet treatment process, vacuum slots 108 may be located
directly beneath the hydraulic entangling manifolds 106 or beneath the foraminous surface 110
downstream of the enlan~ g manifolds 106 so that excess water is withdrawn from the
hydroentangled nonwoven web 112. The foraminous surface 110 may be, for example, a
single plane mesh wire having a mesh size of from about 40 x 40 strands per inch (about 15.7
15 x 15.7 strands per centimeter) to about 100 x 100 strands per inch (about 39.4 x 39.4 strands
per centimeter). The foraminous surface 110 also may be a multi-ply mesh having a mesh size
from about 50 x 50 strands per inch ~about 19.7 x 19.7 strands per centimeter) to about 200 x
200 strands per inch (about 78.7 x 78.7 strands per centimeter).
After fluid jet treatment, the hydroentangled nonwoven web 11 2 may then be
transferred to a non-compressive drying operation, such as a conventional rotary drum
through-air dryer 114 shown in FIG. 10, which has been found to work particularly well. Other
non-compressive and compressive drying operations, such as infra-red radiation, yankee
dryers, steam cans, microwaves, and ultrasonic energy may aiso be used. In the case of
25 compressive drying processes, however, the level of compression of the fibrous web mus~ be
controlled so as not to si~llirical,lly reduce the openness and separation of the fibers or
filaments of the web. A differential speed pickup roll 116 may be used to transfer the
hydroentangled nonwoven web 112 from the roralll;.lous surface 110 to a non-compressive
drying operation. Alternatively, conventional vacuum-type pickups and transfer fabrics may be
30 used.
The through-air dryer 114 may be an outer rotatable cylinder 116 with perforations 118
in colllbil,~lion with an outer hood 120 for receiving hot air blown through the pelr~,ra~ions 118.
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A through-dryer belt 122 carries the hydroentangled nonwoven web 112 over the upper portion
of the through-dryer outer cylinder 116. The heated air forced through the perforations 118 in
the outer cylinder 116 of the through-dryer 114 removes the working fiuid from the web 112.
The temperature of the air forced through the hydroentangled web 112 by the through-dryer
114 may range from about 93 ~C to about 260 ~C. Other useful through-drying methods and
apparatus may be found in, for example, U.S. Pat. No. 2,666,369 and U.S. Pat. No. 3,821,068,
both of which are incorporated herein by reference. After the drying operation, the
hydroentangled nonwoven web 112 is passed to the creping assembly, described hereinbelow.
As a result of the creping process employed in making the creped hydroenLal~ d
nonwoven laminate material of this invention, hydroentangled nonwoven layer 12 (see FIGS. 1
and 2) is creped or"bunched," thereby forming raised areas 16 separated by non-raised areas
18 in nonwoven layer 12 and thus imparting rugosities or wrinkles in nonwoven layer 12.
Within raised areas 16, hydroentangled nonwoven layer 12 may be physically separated from
15 and/or unbonded to support layer 14. The raised areas 16 have a first, low fiber density and
the fibers within the raised areas 16 exhibit a first, high z-directional orientation. As such, the
raised areas 16 are intended to receive and engage the hook elements of a complementary
hook material, as shown in FIGS. 3 and 4. The non-raised areas 18 have a second, relatively
higher fiber density as compared to the raised areas 16 due to compression or compaction of
20 the fibers of nonwoven layer 12 in the non-raised areas and exhibit a second, relatively lower
z-di eclional fiber orientation. The creping imparted to nonwoven layer 12 by the forming
process further serves to increase the basis weight of the nonwoven material, as a larger
amount of nonwoven material is compacted within a given unit area. The basis weight of the
nonwoven material has been observed to increase by as much as a factor of 2, or more,
25 depending, for example, on the degree of creping i" ,parled by the creping apparatus
described hereinafter. The creped structure of nonwoven layer 12 provides resistance to
compression of the fibrous structure of nonwoven layer 12, thereby facilitating entry and
engagement of the hook elements of hook material 22 during use of the hook and loop
ra~.len;"g system. FIG. 5B illustrates in detail the features and contours of nonwoven layer 12.
Support layer 14 can be generally described as any material, including woven or
nonwoven materials or thermoplastic films, that can be suitably bonded to an outer surface of
the nonwoven layer 12 in order to provide a foundation for the nonwoven layer 12. Support
16
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layer 14 can, for example, be formed by the "~aLerial of an underlying substrate, such as the
outer cover or backsheet of an absorbent article. Thus, support layer 14 provides structural
integrity to the creped hydroentangled nonwoven lami. ,ate material, and serves to
dimension~lly st~' :' e the fibers within nonwoven layer 12.
S~ le film formulations used in forming support layer 14 include homopolymers and
- copolymers of ethylene or propylene, such as low density polyethylene (LDPE), linear low
density polyethylene (LLDPE), ethylene/vinyl acetate copolymers (EVA), high density
polyethylene (HDPE), or a mixture of two or more of these polymers. Such films may be mono-
10 layer or multi-layer and can be formed by any suitable film manufacturing process as is well
known in the art, including, for example, blow-molding, cast-extrusion and bioriented-extrusion.
For example, in the specific embodiment shown in FIGS. 1 and 2, support layer 14 is a 0.6 mil
thick, blow-molded mono-layer film sold under the product designation XBPP-133 by
Consolidated Thermoplastics Co., having offices in Dallas, Texas. Based upon nuclear
15 magnetic resonance (NMR) analysis, this film includes 84 percent polypropylene and 16
percent polyethylene, by weight, based upon the total film weight. Other suitable films used in
forming support layer 14 can be made of or include a heterophasic polymer composition as
described in U.S. Pat. No. 5,368,g27 to Lesca et al., or U.S. Pat. No. 5,453,318 to Giacobbe,
the disclosures of which are incorporated herein by reference. Typical commercially available
20 thermoplastic film materials have initial thicknesses ranging from about 0.4 mil to about 5 mils.
If support layer 14 is formed of a nonwoven material, such nonwoven layer can beformed by any suitable known process, such as those described hereinabove.
Although in the embodiments shown, support layer 14 is illustrated as coextensive with
hydroentangled nonwoven layer 12, the present invention is not limited to such embodiments.
~or example, hydroentangled nonwoven layer 12 can be creped singly and then secured or
attached directly to an underlying substrate, such as an outer cover of an absorbent article. In
this alternative embodiment, the substrate functions as a support layer 14. If the outer cover of
an absorbent article forms the support layer 14 of the present invention, the outer cover may
be formed of any s~itable material that provides the required functionality as described herein
for support layer 14. By way of example only, a typical material used in forming absorbent
article outer covers is polyethylene film.
17
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Referring now to FIG. 7 a process and appa(dLus for forming the creped
hydroentangled nonwoven laminate loop material of this invention now will be described. A
suitable process and apparatus for forming such creped nonwoven laminate materials is
described in detail in the co",r"only assigned U.S. Pat. App. Ser. No. 463 ~92 filed on June 5
1995 which is incorporated herein by reference. It should be u"der~lood however that any
process and apparatus suitable for forming a creped hydroenlall~ 'ed nonwoven laminate loop
material having the functionality and attributes described herein with respect to Applicallls'
invention may be employed.
In FIG. 7 apparatus for forming the creped hydroentangled nonwoven laminate loopmaterial of this invention is represented generally as element 30. The apparatus 30 includes a
first web unwind 36 for a first web 38 and an optional second web unwind 32 for a second web
34. For purposes of illustration only the first web unwind 36 shall be described as having a roll
15 of plastic film 38 and the second web unwind 32 shall be described as having a roll of
hydroentangled nonwoven web material 34 such as a hydroentangled spunbond air laid wet
laid or bonded carded web. It should be u,lde,:,Lood however, that unwinds 32 and 36 may be
used to feed any type of hydroentangled web material into the apparatus shown that is
con,paliLle therewith and forms the creped hydroentangled nonwoven laminate loop material
20 of the present invention. It further should be understood that although the apparatus of FIG. 7
shows web unwinds 36 and 32, the creping assembly 30 may be placed in a continuous (in-
line) process with the nonwoven forming, film forming and/or hydroentangling equipment
described herein.
In order to further manipulate the properties of the creped hydroentangled nonwoven
la,n;,l~le loop material formed by the apparatus depicted in FIG. 7, it has been found
advantageous to control the respective rotational speeds of the unwinds 32 and 36. As a
result it is desirable to provide both unwinds with driving and/or braking means (not shown) to
control the rotational speeds of the unwinds, as will be explained in further detail below. Such
driving and/or braking means are widely known to those of ordinary skill in the art and are
commonly used in conjunction with such unwinds to control tension in the web materials being
unwound.
18
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First web 38 (or simply '~veb" if only one unwind is used) is taken off the unwind 36 and
second web 34 is taken off second unwind 32. Both webs 34 and 38 are passed into a creping
assembly 40 that includes a first or pattern roll 42 and a second or an anvil roll 44, both of
which are driven and/or braked with respect to one another so as to create a rotational speed
5 differential between the two rolls 42 and 44. Suitable means for driving the first and second
rolls 42 and 44 include, for example, electric motors (not shown).
-
Pattern roll 42 is a right circular cylinder that may be formed of any suitable, durable
material, such as, for example, steel, to reduce the wear on the rolls during use. Pattern roll 42
10 has a pattem of raised areas 46 separated by a pattern of non-raised or depressed areas 48.
The raised areas 46 are designed to form a nip with the smooth or flat outer surface of
opposedly positioned anvil roll 44, which also is a right circular cylinder that can be formed of
any suitable, durable material. The size, shape and number of raised areas 46 on pattern roll
42 can be varied to meet the particular end-use needs of the creped hydroentangled
1~ nonwoven laminate loop material being formed thereby. Likewise, the pattem of raised areas
46 on pattern roll 42 can be continuous or discontinuous, as neces~it~t~d by the end use
applica~ion. Typically the relative pe,~enL~ge of raised areas per unit area of the pattern roll 42
will range between about 5 and about 50 percent and the average contact area of each of the
raised areas 46 will range between about 0.20 and about 1.6 s~uare millimeters ~mm2).
20 Generally, the height of the raised areas 46 will range from about 0.25 to about 1.1 millimeters
(mm), although heights outside of this range can be used for specific applications if so desired.
The number of contact areas per unit area of the pattern roll 42 generally will range between
about 3 and about 11)0 raised areas per square centimeter (cm~) of the pattern roll 42. The
shape, geometry or footprint of the raised areas 46 on pattern roll 42 also can be varied.
2~ Ovals, squares, circles and diamonds are examples of shapes that can be advantageously
employed.
The temperature of the outer surface of pattern roll 42 can be varied by heating or
cooling relative to anvil roll 44. Heating andlor cooling can affect the features of the web(s)
30 being processed and the degree of bonding of multiple webs being passed through the nip
formed bet\,veen the counterrotating pattern roll 42 and anvil roll 44. The specific ranges of
temperatures to be employed in bonding nonwoven layer 12 to support layer 14 is dependent
upon a number of factors, including the types of materials employed in forming nonwoven
19
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layer 12 and support layer 14, the inlet or line speed(s) of the layers 12 and 14 passin~
through the nip formed between pattern roll 42 and anvil roll 44, and the nip pressure between
pattern roll 42 and anvil roll 44. Common heating techniques include hot oil and electrical
res;slance heating, as are well known to those of ordinary skill in the art
Anvil roll 44 has an outer surface that is much smoother than pattern roll 42, and
pr~fe,~bly is smooth or flat. It is possible, however, for anvil roll 44 to have a slight pattern on
its outer surface and still be considered smooth or flat for purposes of the present invention.
For example, if anvil roll 44 is made from or has a softer surface, such as resin impregnated
10 cotton or rubber, it will develop surface irregularities, yet it will still be considered smooth or flat
for purposes of the present invention. Such surfaces are collectively referred to herein as "flat."
Anvil roll 44 provides the base for pattern roll 42 and webs of material 12 and 14 to contact
and shear against. Typically, anvil roll 44 will be made from steel, or materials such as
hardened rubber, resin-treated cotton or polyurethane.
Anvil roll 44 also may have flat areas separated by depressed areas (not shown) so
that only select areas of anvil roll 44 will contact raised areas 46 of pattern roll 42. The same
technique may be used on pattern roll 42. As a result, creping can be selectively imparted to
specific regions of the web being processed. As with pattern roll 42, anvil roll 44 may be
20 heated and/or cooled to further affect the properties of the webs being processed.
Pattern roll 42 and anvil roll 44 are rotated in opposite directions to one another so as
to draw the webs of materials 12 and 14 through the nip area defined therebetween. Pattern
roll 42 has a first rotational speed measured at its outer surface and anvil roll 44 has a second
25 rotational speed measured at its outer surface, with the second rotational speed of the anvil
roll 44 exceeding the first rotational speed of the pattern roll 42. The inlet speeds of the webs
12 and 14 may be adjusted to be less than, equal to or greater than the first rotational speed
of pattern roll 42.
The locations of the opposedly positioned two rolls 42 and 44 may be varied to create a
nip area 50 between pattern roll 42 and anvil roll 44. The nip pressure within nip area 50 can
be varied depending upon the properties of the web itself or webs themselves and the degree
of bonding andlor creping desired. Other factors which will allow variances in the nip pressure
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will include the speed differential between pattern roll 42 and anvil roll 44, the temperature of
the rolls 42 and 44 and size and spacin~ of the raised areas 46. For such ~"aLerials as.films
and nonwovens, the nip pressure typically will range between about 2.0 and about 6.0
kilograms per lineal millimeter (kg/lmm). Other nip pressures are possible depending upon the
5 particular end use appli ' on desired.
By manipulating the respective rotational speeds of the pattern roll 42 and anvil roll 44
such that the speed of the anvil roll 44 exceeds that of the pattern roll 42, the creped
hydroentangled nonwoven la"~inaLe loop material of the present invention can be formed.
10 Rotating the anvil roll 44 faster than the pattern roll 42 causes the web of material co"la~
the pattern roll 42, which is hydroentangled nonwoven layer 12 in FIG. 7, to be creped,
compacted or bunched in and around the raised areas 46 of pattern roll 42 as it passes
through the nip area 50 formed between the rolls. The web of material contacting the faster
rotating anvil roll 44, however, need not be compacted or bunched. Increasing the speed
1~ differential between the pattern roll 42 and anvil roll 44 has been observed to increase the
amount of crepe in the material being processed. As hydroentangled nonwoven layer 12 and
support layer 14 are bonded together or laminated within the nip area 50, raised areas 16 are
formed wherein the hydroentangled nonwoven material is bunched to form rugosities in
nonwoven layer 12. In the embodiment shown, raised areas 16 encircle bonding points 20
20 within the non-raised areas 18 of nonwoven layer 12. The degree of creping or bunching will
depend not only upon the speed differential of the two rolls, but also upon other processing
conditions, including the windup speeds, the respective roll temperatures and the area
(spacing and depth) between the raised areas 46. Once the webs 12 and 14 pass through the
creping assembly 40, the creped hydroentang!ed nonwoven laminate loop material 52 formed
25 thereby has features and contours as shown in the magnified photograph of FIG. 5B hereof.
Hydroentangled nonwoven layer 12 and support layer 14 are bonded to one another at
a plurality of bond points 20 within the non-raised areas 18 of nonwoven layer 12, thereby
forming a plurality of raised areas 16 in nonwoven layer 12 separating the non-raised areas
30 18. The degree of bonding or aLLacl"~ent between hydroentangled nonwoven layer 12 and
support layer 14 should be sufficient to prevent delamination of layers 12 and 14 when
subjected to the forces and pressures typically exerted during normal use (i.e., during repeated
fastening and removal of the hook elements of a complementary hook material). As noted
21
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above, the non-raised areas 18 adjacent the bond points 20 will have an increased fiber
density, as compared to the fiber density of the raised areas 16 intermediate non-raised areas
18, resulting from the compression or con.paclion of the fibers of nonwoven layer 12 imparted
by the bonding process described above. In the embodimenl shown, bond points 20 are
5 discrete or discor.li"uous bonded areas encircled by raised areas 16 in which nonwoven layer
12 and support layer 14 are less bonded or unbonded. The term "unbonded" as used herein is
meant to refer to the absence of bonds of sufficient strength to withstand the forces typically
encountered during ordinary use of the creped hydroentangled nonwoven laminate material of
the present invention.
Alternatively, hydroentangled nonwoven layer 12 and support layer 14 may be bonded
together along a plurality of bond lines within the non-raised areas 18 of nonwoven layer 12,
thereby forming a plurality of substantially continuous pleats or corrugations in raised areas 16
in nonwoven layer 12. These pleats or corrugations are oriented in a direction generally
15 perpendicular to the machine direction of travel of hydroentangled nonwoven layer 12. By
Ugenerally perpendicular" it is meant that the angle between the longitudinal axis of the
corrugations or pleats formed in nonwoven layer 12, or extensions thereof, and the machine
direction is between 60~ and 120~. As used herein, the term "machine direction" or MD means
the length of a material or fabric in the direction in which it is produced (from left to right in FIG.
20 7). The term "cross machine direction" or CD means the width of a material or fabric, i.e. a
direction generally perpen' llar to the MD. Such bond lines can be continuous ordisconlil,uous and will be generally parallel to one another. By "generally parallel" it is meant
that the bond lines themselves or extensions of the bonds lines will either not intersect, or if
they do intersect, the interior angle formed by the intersection will be less than or equal to 30~.
Although bonding or lamination of hydroentangled nonwoven layer 12 and support
layer 14 is specifically described herein with reference to heated calender rolls 42 and 44
shown in FIG. 7, any suitable pattern bonding method and apparatus may be employed that
achieves sufficient lamination of the two layers 12 and 14. For example, an adhesive bonding
30 process and apparatus as is well known to those of ordinary skill in the art could be utilized to
bond layers 12 and 14 together. Alternatively, an ultrasonic bonding process and apparatus as
is likewise well known to those of ordinary skill in the art could be used.
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As the creped hydroentangled nonwoven laminate loop material 52 exits the creping
assembly 40, the loop material 52 is collected on a web take-up winder 54. As with the first
unwind 36 and second unwind 32, take-up winder 54 is driven by an electric motor or other
drive source which can be varied so as to adjust the speed at which the loop material 52 is
5 wound up into a roll 56. The speed at which the laminate material 52 is wound on the winder
54 will also affect the properties and appea,~,lce of the ",aLerial. Alternatively, take-up winder
54 may be elimlnated and laminate material 52 may continue in-line for further processing in
web converting apparatus (not shown), such as, for example, application onto an outer cover
or bacl~sl~eet of a personal care absorbent article.
~0
Both the inlet speed of the webs 12 and 14 and the withdrawal speed of the laminate
material 52 can be varied to change of the conditions of the process. For example, the inlet
speed of webs 12 and 14 can be equal to or greater than the rotational speed of first or pattern
roll 42, and equal to or slower than the rotational speed of the second or anvil roll 44. Exiting
the nip area 50 formed by pattern roll 42 and anvil roll 44, laminate material 52 can have a
withdrawal speed which is equal to or greater than the rotational speed of pattern roll 42, and
slower or equal to the rotational speed of anvil roll 44.1t is considered advisable, however, to
adjust the withdrawal speed of the laminate material 52 such that sL,t~tching of the material 52
is limited, or avoided entirely, in order to ",di"lai~, the 3-dimensional surface topography of the
20 material 52, and particularly the z-directional orientation of fibers within the raised areas 16.
Once the creped hyd~c.enld,lgled nonwoven laminate loop material of the present
invention is formed, it can be attached to the outer cover or backsheet of a personal care
absorbent article, such as disposable diaper 60 shown in FiG. 6. More specifically, the
25 exposed surface of support layer 14 opposite the surface attached to creped hydroentangled
nonwoven layer 12 can be secured to outer cover 62 of diaper 60 by known attachment
means, including adhesives, thermal bonding, ul~,t,sonic bonding or a combination of such
means. A wide variety of adhesives can be employed, including, but not limited to, solvent-
based, water-based, hot-melt and pressure sensitive adhesives. Powdered adhesive can also
30 be applied to the materials and then heated to activate the powder adhesive and perfect
bonding.
23
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Diaper 60, as is typical for most personal care absorbent articles, includes a liquid
permeable body side liner 64 and a liquid impermeable outer cover 62. Various woven or
nonwoven fabrics can be used for body side liner 64. For example, the body side liner may be
composed of a meltblown or spunbond nonwoven web of polyolefin fibers, or a bonded carded
5 web of natural and/or synthetic fibers. Outer cover 62 is typically formed of a thin thermoplastic
film, such as polyethylene film. The polymer film outer cover may be embossed and/or matte
finished to provide a more aesthetically pleasing appearance. Other alternative constructions
for outer cover 62 include woven or nonwoven fibrous webs that have been constnucted or
treated to impart the desired level of liquid impermeability, or laminates formed of a woven or
10 nonwoven fabric and thermoplastic film. Outer cover 62 may optionally be composed of a
vapor or gas permeable, "breathable" material, that is permeable to vapors or gas yet
subslanlially impermeable to liquid. Breathability can be imparted in polymer films by, for
example, using fillers in the film polymer formulation, extruding the filler/polymer formulation
into a film and then stretching the film sufficiently to create voids around the filler particles,
15 thereby malcing the film breathable. Generally, the more filler used and the higher the degree
of sl,t:tcl ,i. ,g, the greater the degree of breathability.
C~isposed between liner 64 and outer cover 62 is an absorbent core 66 formed, for
example, of a blend of hydrophilic cellulosic woodpulp fluff fibers and highly absorbent gelling
20 particles ~e.g., superabsorbent). Absorbent core 66 is generally compressible, confol",able,
non-irritating to the wearer's skin, and capable of absorbing and retaining liquid body
exudates. For purposes of this invention, absorbent core 66 can comprise a single, integral
piece of material, or a plurality of individual separate pieces of material. The size and
absorbent capacity of absorbent core 66 should be compatible with the size of the intended
25 user and the liquid loading imparted by the intended use of the diaper 60.
Elastic members may optionally be disposed adjacent each longitudinal edge 68 ofdiaper 60. Such elastic members are arranged to draw and hold the lateral, side margins 68 of
diaper 60 against the legs of the wearer. Additionally, elastic members also may be disposed
30 adjacent either or both of the end edges 70 of diaper 60 to provide an elasticized ~,vaistband.
Diaper 60 may further include optional containment flaps 72 made from or attached to
body side liner 64. Suitable constructions and arrangements for such containment flaps are
CA 0223632~ 1998-0~-19
WO 97/19808 PCT/US96/18393
described, for example, in U.S. Pat. No. 4,704,116, to K. Enloe, the disclosure of which is
incorporated herein by reference in its entirety.
To secure the diaper 60 about the wearer, the diaper will have some type of fastening
5 means attached thereto. As shown in FIG. 6, the fastening means is a hook and loop fastening
system including hook elements 74 attached to the inner and/or outer surface of outer cover
62 in the back waistband region of diaper 60 and one or more loop elements or patches 76
made from the loop material of the present invention attached to the outer surface of outer
cover 62 in the front waistband region of diaper 60.
Having described the above embodiments of the present invention, a sample of thecreped hyJI-~enlal~gled nonwoven la,-,inale loop material was formed to further illustrate the
present invention. For coh,parison purposes, a creped non-hydloenlar1gled nonwoven
l~,l,i,la~e material also was formed, as described in commonly assigned U.S. Pat. App. Ser.
No~8/565618, filed on even date herewith, which is incorporated herein by reference. These
sdlllples were tested to determine peel strength and shear strength.
The peel strength of a loop material is a gauge of its functionality. More specifically,
peel sL(el1y~1l is a term used to describe the amount of force needed to pull apart the male and
20 female components of a hook and loop fastening system. One way to measure the peel
strength is to pull one component from the other at a 180 degree angle.
Shear strength is another measure of the strength of a hook and loop fastening system.
Shear strength is measured by engaging the male and female components and exerting a
25 force along the plane defined by the connected surfaces in an effort to separate the two
components.
The test methods used to evaluate these sample l~ate, ials are set forth below.
30 TEST METI~ODS
180~ Peel Stren~th Test
CA 0223632~ 1998-0~-19
WO 97/19808 PCT/US96/18393
The 180~ peel strength test involves attaching a hook material to a loop rnaferial of a
hook and loop fastening system and then peeling the hook material from the loop material at a
180~ angle. The maximum load needed to disengage the two materials is recorded in grams.
To perform the test, a continuous rate of extension tensile tester with a 5000 ~ram full
scale load is required, such as a Sintech System 2 Computer Integrated Testing System
available from Sintech, Inc., having offices in Research Triangle Park, North Carolina. A 75
mm by 102 mm sample of the loop material is placed on a flat, adhesive support surface. A 45
mm by 12.5 mm sample of hook material, which is adhesively and ultrasonically secured to a
sul,slanlially inelastic, nonwoven material, is positioned over and applied to the upper surface
of the loop ,.,ale~ial sample. To ensure adequate and uniform engagement of the hook
material to the loop material, a 41/2 pound hand rolier is rolled over the combined hook and loop
materials for one cycle, with one cycle equaling a forward and a backward stroke of the hand
roller. One end of the fingertab material supporting the hook material is secured within the
upper jaw of the tensile tester, while the end of the loop material directed toward the upper jaw
is folded downward and secured within the lower jaw of the tensiie tester. The placement of
the respective materials within the jaws of the tensile tester should be adjusted such that
rlli. ~al slack exists in the respective materials prior to activation of the tensile tester. The
hook elements of the hook material are oriented in a direction generally perpendicular to the
i"tt:nded directions of movement of the tensile tester jaws. The tensile tester is activated at a
crosshead speed of 500 mm per minute and the peak load in grams to disengage the hook
material from the loop material at a 180~ angle is fhen recorded.
Dynamic Shear Stren~th Test
The dynamic shear strength test involves engaging a hook material to a loop material of
a hook and loop fastening system and then pulling the hook material across the loop material's
surface. The maximum load required to disengage the hook from the loop is measured in
grams.
To conduct this test, a continuous rate of extension tensile tester with a 500~ gram full
scale load is required, such as a Sintech System 2 Computer Integrated Testing System. A 75
mm by 102 mm sample of the loop material is placed on a flat, adhesive support surFace. A 4
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PCT/~JS96/18393
WO 97/1981~8
mm by 12.5 mm sample of hook material, which is adhesively and ultrasonically secured to a
substantially inelastic, nonwoven material, is positioned over and applied to the upper surface
of the loop material sample. To ensure adequate and uniform engagement of the hook
~,ale,ial to the loop material, a 41/2 pound hand roller is rolled over the combined hook and loop
~ ~ materials for five cycles, with one cycle equaling a forward and a backward stroke of the hand
roller. One end of the nonwoven material supporting the hook material is secured within the
- upper jaw of the tensile tester, and the end of the loop material directed toward the iower jaw is
secured within the lower jaw of the tensile tester. The placement of the respective materials
within the jaws of the tensile tester should be adjusted such that minimal slack exists in the
10 respective materials prior to activation of the tensile tester. The hook elements of the hook
material are oriented in a direction generally perpendicular to the intended directions of
movement of the tensile tester jaws. The tensile tester is activated at a crosshead speed of
250 mm per minute and the peak ~oad in grams to disengage the hook material from the loop
material is then recorded.
EXAMPLES
In the examples below, the nonwoven layer was formed of spunbonded filaments made
usinç~ a pilot-scale appal~lus, essentially as described in U.S. 3,802,817 to Matsuki et al. The
20 spunbonded filaments were formed from an extrudable thermoplastic resin which contains
about 80 percent, by weight, of polypropylene homopolymer, and about 20 percent, by wei~ht,
of Montell USA CatalloyTM KS084. The spunbonded filaments were essentially continuous in
nature and had an average fiber size of 2-3 dpf. The spunbond nonwoven web had a percent
bond area of about 11% and a basis weight of about 23.8 grams per square meter (gsm). The
25 support layer was a blown thermoplastic film. The film composition included, on a weight
percent basis based upon the total weight of the film, about 84 percent polypropylene, and
about 16 percent polyethylene. The film had a thickness or bulk of 0.6 mil. This film is sold
under the product designation XBPP-133 by Consolidated Thermoplastics Co.
The spunbond nonwoven web of Example 1 was subjected to hydroentangling usin~
dp,Vdld~lS as shown in FIG. 10. The spunbond web was hydraulically entangled with jets of
water from three manifolds. Each manifold was equipped with a single row of water jets with a
hole density of 12 holes per centimeter and an overall width in the cross machine direction of
,
CA 0223632~ 1998-0~-19
WO 97/19808 PCT/US96/18393
about 20 inches (50.8 centimeters). The hole diameter of each of the holes in the manifold was
0.18 millimeter. The discharge of the jet orifices was between about 4 cm and about ~0 cm
above the spunbond web 8s it traveled at about 6 meters/minute on a polyester mesh forming
wire havin~ an open area of about 55 percent. Each of the manifolds was adjusted for an
5 individual pressure of 1200 psig. Vacuum boxes removed excess water and the treated web
was dried utilizing conventional through air drying equipment.
For comparison purposes, a creped nonwoven lal"i,lale material was formed in which
the spunbond nonwoven layer was not sllhjectQd to hydroentangling. This creped non-
10 hydroenla" 'ed nonwoven lalll- 1~le material, which is illustrated in FIG. 5A, was identical to
the creped hydroentangled nonwoven laminate material of Example 1, except the nonwoven
layer of Example 2 was not subjected to hydroentangling.
The sample laminate materials of Examples 1 and 2 both were formed using a creping
15 process and apparatus, as described herein. The nonwoven layer and film support layer were
passed through the nip formed between two counter-rotating thermal bonding rolls including a
pattern roll and an anvil roll. The nonwoven layer was positioned adjacent to and in contact
with the pattern roll, while the film support layer was positioned adjacent to and in contact with
the anvil roll. The pattern roll was heated to a temperature of about 127 ~C and the anvil roll
20 was heated to a temperature of about 116 ~C. Both rolls were heated using an internal hot oil
system. The nip pressure along the i"le~rdce bet\,veen the pattern roll and the anvil roll was
about 65.7 pounds per lineal inch (pli) (about 1.17 kilograms per lineal millimeter (kg/lmm)).
ExamPle 1
A hydroentangled spunbond nonwoven web and film support layer were formed into acreped hydroentangled nonwoven la",i.,ale loop material using the creping asse,l,bly
described herein. The inlet speed of the hydroentangled nonwoven web into the nip formed
between the pattern roll and anvil roll was about 11.0 meters per minute (m/min.). The pattern
30 roll had a rotational speed of about 6.1 m/min. and the anvil roll had a rotational speed o
about 18.3 m/min., resulting in an anvil roll/pattern roll speed differential of about 3:1.
Example 2
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WO 97/19808 PCT/lJS96/I8393
The creped nonwoven laminate loop material of this example was formed under the
same process conditions and using the same melt-spun filaments described above for
Example 1 except the nonwoven web was not hydroentangled.
The above-described sample materials had the following properties:
TABLE I
FXAMPLEPeel Str~ngthShear Strengfh
NO. ~grams) fgrams)
n=4~ n=4
733 3882
2 532 2990
~The values indicated in Table I above are average values, based upon n measurements
pe, r~ r~ d on each sample material described in Examples 1 and 2.
Although specific values for peel and shear strength were provided for the above-
described examples, the creped hydroentangled nonwoven laminate loop material of the
15 present invention should not be limited to such values. Generally, the creped hydroentangled
nonwoven laminate loop material should have a combination of peel and shear strength that is
suitable for its intended end use application. Peel strengths in the ran~e of from about 400
grams to about 900 grams, or higher, are considered suitable for use in the present invention.
Likewise, shear strengths ranging from about 3000 grams to about 4800 grams, or higher, are
20 considered suitable for use in the present invention.
In addition, the attachment strength of the hydroentangled nonwoven layer to thesupport layer should be sufficient for the intended use of the creped hydroentangled
nonwoven laminate loop material. The degree of attachment or lamination between the creped
25 hydrc enldngled nonwoven layer and the support layer is another gauge of the functionality of
the loop material. Delamination refers to the separation of the layers of a laminate material
when the bonding mechanism fails. Attachment or bond strength is a measure of the average
peel force required to separate the component layers of a laminate material. In order to avoid
29
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WO 97/19808 PCT/US96/18393
dll ~ latiOn 0~ the nonwoven and support layers during use, the attachment strengtll should
exceed about 500 grams, or suitably exceed about 80U grams Likewise, tlle tolal basis weight
of the creped hydroenlangled nonwovell laminate loop material may be adapted to suit its
intended end use applicalion Total basis weights in the rarlge of from aboul 34 ~rams per
5 square meter to about 85 grams per square meter, ar-d more particularly in the ranye of from
abou( 44 grams per square meter to aboul 75 grams per square meler, ale conskJe~ed suitable
for use in the present invention
It is contemplated that the creped lly-iroentangled nonwovell lalninate loop material
10 constructed in accordance Witll the present invenliorl will ~e tailored and adjusled by those of
ordinary skill in Ule art to accomltlodale various levels of performa17ce demalld imparted during
actual use Accordingly, while this invelltiorl has been described by reference to tl-e above
embodiments and examples, it will be un<lerstood that this inverllion is capable of further
nnodifications This application is, therefore, intended to cover any variations, uses or
15 adaptations oF the invention followiny the general principles thereof, and including such
departures from the present disclosure as come within known or customary practice in the art
to which this invention pertains and fall witllill the limits of the appeslded claims
