U.S. patent application number 10/196177 was filed with the patent office on 2004-01-22 for method for making a hydroentangled nonwoven fabric and the fabric made thereby.
This patent application is currently assigned to Avgol Ltd.. Invention is credited to Bonneh, Achai, Goldwasser, Moshe.
Application Number | 20040010894 10/196177 |
Document ID | / |
Family ID | 29780180 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040010894 |
Kind Code |
A1 |
Goldwasser, Moshe ; et
al. |
January 22, 2004 |
Method for making a hydroentangled nonwoven fabric and the fabric
made thereby
Abstract
A process for making a single layer or multi-layer nonwoven
material having improved cross-directional strength and feel, and
the nonwoven material made thereby, is described. The process
provides a nonwoven material including at least one layer formed of
polymeric continuous filaments. The layer(s) are formed in a
continuous sequential manner, i.e., a subsequent layer being formed
on top of a preceding layer or layers. Thereafter, in the absence
of any prebonding, the layer(s) are subjected to hydroentanglement.
The basis weight of the nonwoven material is from about 17 to 150
gsm. The nonwoven material has improved properties based on
treating the layer(s) by hydroentanglement. Varying the number of
water jets and the pressure of the water allows variance in the
properties obtained in the final product. Other physical properties
can also be imparted to or changed in the nonwoven material by
inclusion of an additive in a polymer melt during formation of the
filaments, or by topical treatment following treatment of the
layers of the nonwoven material by hydroentanglement.
Inventors: |
Goldwasser, Moshe; (Tel
Aviv, IL) ; Bonneh, Achai; (Kokhav Yair, IL) |
Correspondence
Address: |
Breiner & Breiner, L.L.C.
P.O. Box 19290
Alexandria
VA
22320-0290
US
|
Assignee: |
Avgol Ltd.
Holon
IL
|
Family ID: |
29780180 |
Appl. No.: |
10/196177 |
Filed: |
July 17, 2002 |
Current U.S.
Class: |
28/104 |
Current CPC
Class: |
D04H 1/56 20130101; D04H
1/492 20130101; D04H 3/11 20130101; D04H 1/498 20130101 |
Class at
Publication: |
28/104 |
International
Class: |
D04H 003/10 |
Claims
It is claimed:
1. Process of forming a nonwoven material comprising providing
continuous thermoplastic polymer filaments; laying the continuous
filaments upon a moving support to provide at least one layer on
said support; joining the continuous filaments of the at least one
layer together by hydroentangling the filaments in absence of
prebonding of the filaments forming said at least one layer,
wherein said hydroentangling is provided by subjecting said at
least one layer to water emitted at a pressure of from about 20 to
about 250 bar from a plurality of water jets with at least 25 water
jets per linear inch of planar surface of said at least one
layer.
2. Process according to claim 1 wherein said polymer is a
polyolefin.
3. Process according to claim 2 wherein said polymer is
polypropylene.
4. Process according to claim 1 wherein said polymer is a
polyester.
5. Process according to claim 1 further comprising, following said
hydroentangling, topically treating said at least one layer with an
additive to impart to or change a physical property in said at
least one layer.
6. Process according to claim 1 further comprising incorporating an
additive in said continuous thermoplastic polymer filaments to
impart to or change a physical property of said filaments.
7. Process according to claim 5 wherein said additive renders said
nonwoven material at least in part lyophobic, lyophilic, fire
retardant, antistatic, and/or absorbent.
8. Process according to claim 6 wherein said additive renders said
nonwoven material at least in part lyophobic, lyophilic, fire
retardant, antistatic, and/or absorbent.
9. Process according to claim 1 wherein said at least one layer is
spunlaid or meltblown.
10. Process according to claim 1 wherein said water jets have
nozzle orifices ranging from about 0.1 to about 0.2 mm in
diameter.
11. Process according to claim 1 wherein said at least one layer is
supported on a series of perforated godet rollers during said
hydroentangling.
12. Process according to claim 1 wherein said continuous filaments
are provided at a denier of from about 0.8-5 dpf.
13. Process according to claim 1 further comprising, following said
hydroentangling, providing a pattern on said nonwoven material.
14. A nonwoven material made according to the process claimed in
any one of claims 1 to 13.
Description
FIELD OF INVENTION
[0001] The invention is directed to a method for making a nonwoven
material including forming at least one layer of continuous
filaments and subjecting the layer(s) to hydroentanglement in the
absence of any prebonding of the continuous filaments in the
layer(s) prior to being subjected to hydroentanglement, as well as
the nonwoven material made thereby. The nonwoven material has
improved physical properties such as increased tensile and
elongation properties, hand and drape, very low surface linting,
etc. The nonwoven material provided is preferably spunlaid or
meltblown or is a composite and can be present as a single layer or
as one or more layers in a multi-layer nonwoven material. The
material of the invention is in particular useful in personal care
absorbent products, such as feminine hygiene products, diapers,
adult incontinence products, etc., as well as for dry or wet wipes,
medical products which come in contact with skin, and the like.
BACKGROUND OF THE INVENTION
[0002] Hydroentangled nonwoven webs and processes for making such
webs are known in the art. In conventional processes, the process
is usually limited by one or more critical parameters in order to
provide a nonwoven product having a desired characteristic or
quality dictated by the use to which the material is to be applied.
In particular, prior art hydroentanglement processes require some
type of prebonding of the filaments or fibers prior to being
subjected to hydroentanglement. This adds to the time and cost of
the process, but also affects the properties of the resulting
nonwoven material, in particular as to the softness and durability
of the material. Examples of known hydroentanglement processes are
as follows:
[0003] U.S. Pat. No. 5,023,130 describes a process for water jet
entangling continuous filament fibers to form a web wherein the
combination of the water jet pressure and total impact energy
provided by the water jets is controlling for producing a nonwoven
web suitable for producing durable comfortable apparel. At column
4, lines 4-9, the patent teaches that "lightly consolidated webs"
are suitable for use in the described process.
[0004] EP 0 333 211 B1 describe nonwoven fibrous hydraulically
entangled web materials formed from a laminate of at least one
layer of meltblown fibers and at least one layer of nonwoven
fibrous material such as pulp fibers, staple fibers, meltblown
fibers, continuous filaments, nets, foams, etc. Conventional
hydraulic entangling techniques are disclosed as being suitable for
use.
[0005] EP 0 333 228 B1 describes hydraulically entangled nonwoven
fibrous material formed by entangling a coform of an admixture of
non-elastic meltblown fibers and fibrous material.
[0006] U.S. Pat. No. 3,508,308 describes a jet treatment apparatus
for producing entangled nonwoven fabrics involving supporting a
layer of fibrous material on a smooth supporting member and
subjecting the layer to multiple high pressure water jets. The
layer of fibrous material is staple fibers or continuous filaments
in the form of mats, batts, webs and the like, including layered
composites or blends.
[0007] International Published Application WO 01/51693 A1 discloses
an apparatus and method for continuously producing a multi-layer
nonwoven fabric. The process involves sandwiching a first web of
cellulosic fibers between two webs of spunlaid filaments.
Consolidation of the resulting complex is then by
hydroentanglement.
[0008] U.S. Pat. No. 5,801,107 describes a nonwoven fibrous
material of pulp fibers which are loosened and rearranged by low
energy jets of liquid so that the nonwoven material can absorb,
transport and release liquid. The material is provided with a
defined porosity.
[0009] U.S. Pat. No. 6,163,943 describes nonwoven material based on
a foam-formed fibrous web, staple fibers and a layer of continuous
filaments which are hydroentangled together to form a composite
material.
[0010] International Published Application WO 01/53588 describes a
nonwoven composite material made from at least one spunbonded woven
fiber and wood pulp layer. The nonwoven fiber is compressed or
calendered as a prebonding treatment prior to being subjected to
hydrodynamic water needling.
[0011] U.S. Pat. No. 6,321,425 B1 describes a hydroentangled
nonwoven fabric. The precursor web used to form the nonwoven fabric
is subjected to compression and light bonding prior to
hydroentanglement in order to facilitate handling of the web.
[0012] U.S. Pat. No. 5,151,320 describes a hydroentangled
spunbonded composite fabric formed from a base web which is a
prebonded web made from continuous filaments.
[0013] The conventional processes as known in the art produce
nonwoven materials having strength in the tensile direction but not
in the cross-direction. When the material is pulled in a
cross-direction, the material will stretch and ultimately tear.
Thus, a nonwoven material having both good tensile and
cross-directional strengths is desirable, as well as a consolidated
continuous process for producing such material. The ability to
provide such improved material from a single raw material, in a
continuous process in particularly being capable of pre-formation
treatment or post-formation treatment to affect physical properties
of the material, is desirable.
OBJECTS OF THE INVENTION
[0014] Accordingly, a primary object of the present invention is to
provide a method for making a nonwoven material utilizing
hydroentanglement as a means of bonding thereby eliminating the
need for thermal bonding or chemical bonding agents, and a nonwoven
material having improved strength.
[0015] More particularly, it is an object of the invention to
provide a single layer or multi-layer nonwoven material having
improved cross-directional strength made in a continuous in-line
process wherein at least one layer of spunlaid or meltblown
continuous filaments are bonded together by hydroentanglement in
the absence of any prebonding such as by chemical, thermal
compression, needling, calendering or the like.
[0016] It is a further object to provide a process for forming a
nonwoven product from at least one layer of spunlaid or meltblown
continuous filaments which require no prebonding treatment prior to
being subjected to hydroentanglement by a plurality of high
pressure water jets which can control the properties obtained in
the resulting product.
[0017] It is a further object that the continuous filaments of each
layer present are made from a thermoplastic polymer, preferably a
polyolefin or polyester, and most preferably polypropylene.
[0018] A further object is to provide a nonwoven material with
improved tensile and elongation properties, in particular increased
strength in the cross-direction, so that the material is suitable
for processing and use as a barrier for solids, such as
superabsorbent polymers (SAPs) as used in diapers, adult
incontinence products, feminine hygiene products and the like.
[0019] A further object is to alter one or more physical
characteristics of the nonwoven material, such as the fluid
handling property (e.g. hydrophobicity and hydrophilicity) of at
least a portion of the nonwoven material, flame retardancy,
absorbency, antistatic nature and the like, by incorporating one or
more components into the nonwoven material, such as an additive
added to an extruder polymeric melt or topical application to the
resulting hydroentangled nonwoven material.
BRIEF DESCRIPTION OF THE INVENTION
[0020] A durable improved strength hydroentangled single layer or
multi-layer nonwoven material is described. The nonwoven material
is formed from at least one layer of continuous filaments, which
are preferably spunlaid or meltblown, and the filaments are bonded
by hydroentanglement in the absence of any prebonding of the
filaments prior to being subjected to hydroentanglement. The
filaments are preferably of a thermoplastic polymer, more
preferably a polyolefin or polyester, and most preferably
polypropylene. Certain properties of the nonwoven material, such as
phobicity, philicity, flame retardancy, absorbency, antistatic
nature, etc. can be imparted to or changed in the nonwoven material
by including a suitable additive in the polymer to be extruded
during production of the one or more layers of filaments, or by
topically treating the resulting nonwoven material following
hydroentanglement. For example, an additive or topical treating to
affect hydrophilicity involves the use of a surfactant.
[0021] The process of the invention provides a nonwoven material
having improved tensile and elongation properties as well as an
improved hand. Notably the nonwoven material is provided with a
cottony velveteen feel. The improved properties are obtained by
provision of the spunlaid or meltblown layer(s) from continuous
filaments in a continuous in-line process which includes
hydroentangling the continuous filaments as part of the in-line
process without any prebonding of the filaments. The process of the
invention allows for the use of a single raw material, such as
polypropylene, and avoids the necessity of using staple fibers.
Staple fibers require a separate process of manufacture, interim
storage and subsequent incorporation into another process to make a
final product. Staple fibers were believed necessary for use in
conventional processes to obtain hydroentangled fibers since it was
believed necessary to have defined end structures to obtain the
desired knotting during hydroentanglement to achieve bonding of the
fibers. The process of the invention allows for the use of
continuous filaments, thereby allowing for a continuous in-line
process of production and treatment by hydroentanglement to join or
bond the filaments together.
[0022] More in particular, a desired spunlaid or meltblown layer
(or layers) is (are) produced by a conventional method for
producing continuous filaments. The continuous filaments are laid
onto a moving support, e.g. a moving mesh screen or a series of
moving supports, e.g. perforated godet rollers. When a multi-layer
material is being produced, second and subsequent layer(s) are laid
sequentially upon the prior formed layer(s) on the moving support.
The layer or layers then are subjected to hydroentanglement. No
prebonding, e.g. by heat, compression, calendering, chemical or the
like, is utilized. The moving support is structured to extend or
transfer the layer or layers to the hydroentanglement equipment
such that the layer(s) is essentially continually supported to the
hydroentanglement apparatus. This serves to maintain the structure
of the layer(s) and allow direct impact of water on the layer(s)
from the plurality of high pressure water jets providing the
hydroentanglement while avoiding flying apart of the layer(s) when
the water hits the layer(s).
[0023] In the hydroentanglement process, a plurality of water jets
are positioned above the moving support(s). The moving support(s)
is preferably structured to allow for drainage of the water. The
screen mesh or perforations in the godet rollers preferably have
openings with a diagonal in the range of from about 0.1 to 2.0 mm.
The number of water jets present and the pressure at which the
water is ejected are critical in determining the properties
obtained in the treated nonwoven material. The water jets are
positioned so as to be spaced apart and provide about 50 water jets
per linear inch. The water jets are arranged to cover the width of
the layer(s) being treated. A single line or a plurality of lines
of water jets may be used. The support(s) for the layer(s) moves at
a speed generally in a range of about 20 to 250 meters per minute.
Thus, adequate exposure to the water jets is provided. Water is fed
under pressure through nozzles, preferably at a pressure of from
about 20 to 250 bar. Nozzle orifice diameters can be from about 0.1
to 0.2 mm to provide the desired sized water streams. A preferred
combination of number of water jets, pressure and orifice size is
as follows: number of jets 25 to 50 per linear inch, pressure about
20 to 200 bar, and orifice size about 0.1 to 0.2 mm. If a material
with looser filament structure is desired, the parameters are as
follows: number of jets 25 to 50, pressure about 20 to 150 bar and
orifice size about 0.1 to 0.2 mm. If a material with a tight
filament structure is desired, the parameters are as follows:
number of jets 30 to 50, pressure about 50 to 250 bar and orifice
size about 0.1 to 0.2 mm.
[0024] The filament content of the nonwoven material is preferably
of high density in order to prevent movement or migration of solids
from one side to another of the material while at the same time
allowing fluids to move through quickly based on additive or
topical treatment with a surfactant. More particularly, the basis
weight of the overall nonwoven material is preferably about 17 to
150 gsm (grams per square meter). In a multi-layer nonwoven
material, each layer is preferably from about 8 to 80 gsm as to
basis weight.
[0025] The hydroentangled nonwoven material will be hydrophobic
when made from a thermoplastic polymer, such as polypropylene. To
render the hydroentangled nonwoven material hydrophilic, which is a
desired property in many conventional uses of nonwoven materials, a
surfactant can be incorporated into the material. A suitable
surfactant for use as an additive in a polymer melt is
STANDAPOL.TM. 1353A or 1480, as sold by Cognis Deutschland GmbH,
Dusseldorf, Germany, which are each a fatty ester. A preferred
surfactant for topically treating the formed hydroentangled
nonwoven material is STANTEX.RTM. S 6327, as sold by Cognis
Deutschland GmbH, which is a blend of fatty acid esters. An example
of a suitable topical treatment for imparting hydrophilicity to the
nonwoven material is as described in U.S. Pat. Nos. 5,709,747 and
5,885,656, the disclosure of each patent being incorporated herein
by reference. The surfactant is preferably present in the nonwoven
material in an amount of from about 0.2 to 3.0 wt. %.
[0026] The nonwoven materials of the invention are useful in a wide
variety of applications. For example, the nonwoven material is
useful as a component of absorbent products such as disposable
diapers, feminine hygiene products, adult incontinence products;
medical products which contact the human skin such as surgical
gowns and masks; disposable dry or wet wipes (both plain and
impregnated dry wipes); industrial garments; filtration media; etc.
The nonwoven material of the invention is in particularly well
suited for those applications requiring both high strength and soft
hand feel. The nonwoven material is also suitable for use as a
barrier layer for retaining solids within a desired location, e.g.,
SAPs in diapers, adult incontinence products and feminine hygiene
products. Continuous filament spunmelt webs subjected to water jet
bonding have improved wet strength properties making the material
in particularly useful in wet wipe applications, such as baby
wipes, hard surface cleaning wipes, general purpose
solution-containing wipes, specialty wipes having graphics applied
thereto, and the like. Dry wipes include static dusting wipes or
mops and wipes impregnated with a substance which is activated on
addition to water.
[0027] The nonwoven material of the invention, following
hydroentangling, further can be provided with a pattern, such as by
conventional embossing or the like, to provide aesthtic appeal
and/or enhancing fluid absorption, fluid retention, and fluid
channeling characteristics in the nonwoven material.
BRIEF DESCRIPTION OF DRAWING
[0028] FIG. 1 is a schematic of a process for producing nonwoven
material according to the invention.
[0029] FIG. 2 is a schematic of a preferred support for use during
transfer and hydroentanglement and a positioning of water jets in
relation thereto.
DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS
[0030] The hydroentangled nonwoven material provided by the process
of the invention includes at least one layer of continuous
filaments or fibers bonded by hydroentanglement in the absence of
any prebonding of the filaments. The nonwoven material can be a
single layer or multi-layer and include a combination of spunlaid
and/or meltblown filament layer(s). The filaments forming the at
least one layer are polymeric and continuous. The filaments can be
made using conventional extrusion apparatus and techniques. The
invention avoids the use of staple fibers. Preferably when a single
layer, the nonwoven material is spunlaid. The hydroentangled
nonwoven material of the invention has a superior tensile and
elongation properties as compared to hydroentangled nonwoven
materials made from staple fibers.
[0031] To provide a nonwoven material with high strength in the
machine direction and cross-direction as well as having improved
processability, both during manufacture and after manufacture, the
hydroentangled nonwoven material preferably has a basis weight of
about 17 to 150 gsm. More preferably the nonwoven layer has a basis
weight of from about 25 to 100 gsm, most preferably from about 30
to 70 gsm.
[0032] The filaments of the layer(s) is (are) made of a
thermoplastic polymer. Suitable polymers include polyolefins such
as polypropylene and polyethylene; polyesters such as polyethylene
terephthalate; polyamides; polyacrylates; polystyrene;
thermoplastic elastomers; and blends of these and other known fiber
forming thermoplastic materials. The preferred useful polymer is
polypropylene. If the nonwoven material is multi-layer, each layer
is preferably of the same polymeric material. The process of the
invention is advantageous for providing improved physical
properties while using one raw material and an in-line continuous
process to obtain the desired product.
[0033] The denier size of the filaments is effective to alter
physical properties of the resulting material. Preferably the
denier size is about 0.8-5 dpf to provide a nonwoven material of
desired strength.
[0034] Various physical properties, such as hydrophilicity, can be
imparted to at least one portion of or completely to the
hydroentangled nonwoven material depending on the use to which the
nonwoven material is to be applied. At least one portion of the
nonwoven material includes where one or more layers in their
entirety are modified as to a given property, or any preselected
portion or one or more of the layers have a preselected area
thereof modified as to a preselected property. The manner of
imparting a particular property to the nonwoven material can be
based on the inclusion of an additive in the polymer melt or by
topical treatment. This will be further evident from the
description below of the method of making the nonwoven material.
Properties which can be affected include fluid phobicity, fluid
philicity, fire retardancy, absorbency, softness, antistatic
nature, etc.
[0035] The method of the invention for making a nonwoven material
will be described in relation to the figures. An advantage of the
method of the invention is the provision of a single layer or
multi-layer nonwoven material in a process which combines the
manufacture of continuous thermoplastic polymer filaments, the
formation of a layer therefrom and, if desired, the combining of
multiple layers, and thereafter treating along the same processing
line, without any prebonding of the filaments, of the layer or
layers with a plurality of water jets to provide a bonded nonwoven
material with improved strength and feel. This improves on
conventional multi-stage processes wherein staple fibers are made
by a first process, stored and subsequently used to form a product
in a separate process, or a first layer is made and then processed
for storage or use in another process. The conventional processes
require multiple lines and stages which necessarily include lost or
down time between processing stages. The invention provides for a
consolidated continuous process in terms of space, time, material
storage, etc. Additionally, savings are achieved by not requiring
prebonding equipment or processing prior to hydroentanglement.
[0036] With reference to FIG. 1, a moving support 1 (which can be a
belt, mesh screen, or the like) moving continuously along rollers 3
is provided beneath the exit orifices for one or more extruders,
illustrated for example as extruders 5, 7 and 9. Extruder 5
receives a polymeric melt which is extruded through a substantially
linear diehead 11 to form a plurality of continuous filaments 13
which randomly fall to the moving support 1 to form a layer 15,
preferably, of spunlaid fibers thereon. The extrusion process
parameters used are conventional and as known to one skilled in the
art. The diehead includes a spaced array of die orifices having
diameters of preferably about 0.1 to about 1.0 millimeters (mm).
The continuous filaments following extrusion are quenched, such as
by cooling air.
[0037] Positioned downstream in relation to the moving support 1 in
the processing direction can be additional extruders, 7 and/or 9
for example, for providing continuous filaments 17 and/or 21, which
can be, for example, spunlaid or meltblown. Extruders 7 and 9 can
make additional continuous filaments as described in relation to
continuous filaments 13. Filaments 17 and 21 randomly fall to
moving support 1 and are laid atop a preceding deposited layer to
form superposed layers 19 and 23, respectively. Thus, if desired,
along one continuous line a multi-layer nonwoven material can be
provided using continuous filaments.
[0038] The single layer or stacked layers are then joined or bonded
together to form a coherent material by hydroentanglement utilizing
a plurality of water jets 25 such as illustrated in FIGS. 1 and 2.
Prebonding, such as conventional compression, thermal bonding,
calendering or the like, of the layer(s) together to provide
interlocking of the filaments is not required. Hydroentanglement
therefore is conducted in the absence of conventional processes
such as thermal bonding, chemical bonding, adhesive bonding,
mechanical punch needling and the like, to provide a nonwoven
material having acceptable physical properties, and in fact
superior tensile and elongation properties as compared to nonwoven
materials based on hydroentangled staple fibers.
[0039] The process of the invention provides hydroentanglement of
continuous filaments. In conventional processes of
hydroentanglement, staple fibers are used in order to provide free
end structures capable of providing knotting upon being subjected
to water jets. Conventional processes provide nonwoven material
which have adequate strength in the tensile direction but not in
the cross-direction. Thus, upon being subjected to stretching,
conventional nonwoven materials will tear. The present invention
provides for hydroentanglement of continuous filaments resulting in
a finished product with improved cross-directional strength and
improved feel. The finished product has a cottony velveteen feel.
Further, the raw material used can be the same for each layer
present in the product. This additionally results in a very
economic process and thus economically advantageous product. If
desired, other filaments or pulp can be added to further enhance
the improved properties. However, such are not required. The
continuous filaments utilized can have a variety of deniers, e.g.,
preferably about 0.8-5 dpf, and/or bicomponent filaments to further
alter the physical properties of the nonwoven material. Deniers of
about 0.8 to 5 dpf are preferred to enhance the properties of
softness and uniformity.
[0040] The hydroentanglement process of the invention involves
moving the formed layer or layers along moving support 1 to the
hydroentanglement station 27. A transfer belt 29 and godet rollers
33, or other equivalent structures, serve to essentially maintain
the layer(s) on a support surface so that when the layer(s) are hit
with water from the water jets, the filaments do not fly apart.
FIG. 2 illustrates a preferred embodiment of hydroentanglement
according to the present invention. The single layers or stack of
layers is indicated at 28 which moves to a transfer belt 29 moving
around rollers 31. From transfer belt 29, the layer(s) move along
godet rollers 33. Godet rollers 33 will have a screen which allows
for the passage of water therethrough for drainage. Water jets are
depicted at 25. Initial water jet treatment can begin in relation
to transfer belt 29. Other water jets 25 are spaced in relation to
godet rollers 33 in order to meet the parameters as more
specifically described below. The resulting hydroentangled nonwoven
material 35 is then transported by means of tension roller 36 for
subsequent treatments as desired, e.g. topical treatment, drying,
winding, embossing, etc. The support which passes beneath the water
jets is preferably a series of moving supports. Perforated godet
rollers, as illustrated in FIG. 2, preferably have openings with a
diagonal of from about 0.1 to about 2.0 mm. This allows for good
support and drainage of the water. Drainage can be simply obtained
by gravity feed or else by utilization of a vacuum box or by other
conventional structures.
[0041] The ability to determine and control the properties obtained
in the nonwoven material is based on the number of water jets
present, and the pressure of the water ejected from the water jets
and applied to the nonwoven material. Water jets are present in
number so as to provide from 25 to 50 water jet streams per linear
inch of nonwoven material with the water being ejected at a
pressure of from about 20 to about 250 bar. The orifice of the
water jet nozzles are preferably from about 0.1 to about 0.2 mm in
diagonal. The layer(s) preferably move at a speed of from about 20
to about 250 meters per minute while being subjected to the water
jets. The water jets preferably are positioned over the nonwoven
material being treated and in one or more lines extending across
the width of the layer(s) being processed at essentially a right
angle to the direction of advance of the layer(s).
[0042] As above described, the number of water jets and the
pressure utilized can be varied so as to provide nonwoven material
having different qualities. Examples of different operating
parameters which can be used during hydroentanglement and the
different physical properties affected and final product provided
are described below.
1TABLE 1 LIQUID ABSORPTIVE CAPACITY Dimensions of Test Piece: 100
.times. 100 mm Liquid: Water Liquid Dry Wet Absorptive Material
Type Mass (g) Mass (g) Capacity (Wa) Treatment 60 gsm (1.4 den)
1.258 9.288 635.0% Cognis 1480 1.305 9.679 1.320 9.671 1.300 9.278
1.288 9.643 60 gsm (2 den) 1.308 9.299 595.4% Cognis 1480 1.324
9.418 1.327 8.891 1.306 8.655 1.297 9.367 60 gsm (2 den) 1.325 10.5
663.1% Cognis 1480 Patterned 1.300 9.73 "Dots" 1.253 9.194 1.309
10.200 1.298 9.865 50 gsm 1.040 8.786 737.6% Cognis 1480 (1.4 den)
1.075 8.911 1.035 8.626 1.049 8.723 1.028 8.736 50 gsm (2 den)
1.082 8.659 695.7 Cognis 1480 1.099 8.793 1.095 8.479 1.094 8.761
1.076 8.643 50 gsm 1.140 11.709 848.9% Cognis 1480 (1.4 den) 1.152
10.387 Patterned 1.142 10.460 "Waves" 1.099 10.167 1.129 11.002
[0043]
2TABLE 2 LIQUID ABSORBENCY TIME Dimensions of Test Piece: 100
.times. 100 mm Liquid: Water Liquid Average Liquid Absorbency
Absorbency Material Type Time (Sec.) Time (Sec.) Treatment 60 gsm
(1.4 den) 2.83 3.02 Cognis 1480 2.95 3.28 60 gsm (2d en) 2.81 3.04
Cognis 1480 3.43 2.88 60 gsm (2 den) 3.10 3.20 Cognis 1480
Patterned "Dots" 3.29 3.20 50 gsm (1.4 den) 4.38 4.47 Cognis 1480
4.61 4.43 50 gsm (2 den) 4.64 4.62 Cognis 1480 4.94 4.27 50 gsm
(1.4 den) 14.68 13.34 Cognis 1480 Patterned "Waves" 10.69 14.65
[0044]
3TABLE 3 LIQUID WICKING RATE Dimension of Test Piece: 100 .times.
100 mm Liquid: Water Average Type of Sample 1 Sample 2 Sample 3
Sample 4 Sample 5 Capillary Material Time (Sec) (mm) (mm) (m) (m)
(m) Rise 60 gsm MD 10 20 18 17 18 16 17.8 (1.4 den) 30 29 28 26 24
22 25.8 60 32 33 30 31 29 31.0 60 gsm MD 10 20 19 17 18 17 18.2 (2
den) 30 25 27 24 22 23 24.2 60 31 33 30 30 31 31.0 60 gsm MD 10 20
21 21 21 22 21.0 Patterned 30 28 27 26 27 28 27.2 "Dot" 60 34 35 32
33 35 33.8 50 gsm MD 10 5 8 4 3 5 5.0 (1.4 den) 30 8 11 6 5 9 7.8
60 12 14 9 8 12 11.0 50 gsm MD 10 10 11 11 12 10 10.8 (2 den) 30 15
16 15 16 13 15.0 60 18 19 19 18 17 18.2 50 gsm MD 10 5 4 5 4 5 4.6
(1.4 den) 30 10 8 9 9 8 8.8 "Waves" 60 12 10 12 11 11 11.2
[0045]
4TABLE 4 TENSILE STRENGTH Tensile Tensile Strength Elongation
Strength Elongation Type of Material MD (N/5 cm) MD (%) CD (N/5 cm)
CD (%) 60 gsm (1.4 den) 209.1 106.3 153.6 136.9 60 gsm (2 den)
205.06 100.5 150.6 131.8 60 gsm (2 den) 194.4 112.7 153.7 131.9
Patterned "Dots" 50 gsm (1.4 den) 169.2 101.2 119.4 122.8 50 gsm (2
den) 163.7 89.3 118.5 132.6 50 gsm (1.4 den) 144.5 96.0 113.5 115.9
Patterned "Waves"
[0046] Physical properties (e.g., fluid phobicity, fluid philicity,
fire retardancy, absorbency, antistatic nature, etc.) can be
imparted to or changed in the nonwoven material in different ways.
For example, subsequent to hydroentanglement and dehydration of the
layer(s), the nonwoven material can be subjected to topical
treatment 37, such as described in U.S. Pat. Nos. 5,709,747 and
5,885,656 which are incorporated herein by reference. As described
therein, topical treatment can be to preselected areas depending on
the use to which the nonwoven material will be applied. For
example, if used in the manufacture of a diaper, a central areal
portion may be treated with a surfactant to impart a hydrophilic
character thereto. For example, to affect hydrophilicity, a
surfactant can be used, such as STANTEX.RTM. S 6327, as sold by
Cognis Deutschland, GmbH, Dusseldorf Germany, which is a blend of
fatty acid esters. The surfactant is a liquid suitable for topical
application to the nonwoven material. Other examples of surfactants
suitable for use include PPH 53 as sold by Dr. Bohme GmbH, Germany;
and PP 842 as sold by Uniquema, United Kingdom.
[0047] Alternatively, physical properties can be imparted to or
changed in the nonwoven material by providing a suitable additive
to the extrusion polymeric melt fed to one or more of extruders 5,
7 and/or 9. A suitable surfactant additive to affect hydrophilicity
is STANDAPOL.TM. 1353A or 1480, sold by Cognis Deutschland, GmbH,
which each are a fatty ester(s). These additives maybe present in
either liquid or granular form. Other examples of surfactants
suitable for use include PPH 53 as sold by Dr. Bohme GmbH, Germany;
and PP 842 as sold by Uniquema, United Kingdom. Whether a
surfactant additive is fed to one or more of extruders 5, 7 and/or
9 depends on the characteristics of the nonwoven material desired.
For example, whether a complete strike through of liquid is desired
or only a partial strike through is desired.
[0048] A surfactant is preferably present in an amount of about
0.2-3.0% by weight of the nonwoven material when the nonwoven is
hydrophobic and is to be rendered hydrophilic.
[0049] Other properties of the nonwoven material can be affected,
such as fire retardency, absorbency, antistatic nature and the
like, by additive or topical application of an appropriate
modifying component as described above with regard to affecting the
hydrophobic property of the nonwoven material.
[0050] Following hydroentanglement, and topical treatment if
carried out, the nonwoven material is subjected to conventional
drying and winding so as to provide a finished product ready for
use.
[0051] Also following hydroentanglement, the resulting nonwoven
material can be subjected to embossing or other conventional
process to provide a pattern to the nonwoven material. The pattern
can provide aesthetic appeal and/or enhance certain physical
properties, for example fluid absorption, fluid retention and fluid
channeling or direction control of fluid upon contact with the
material to control the site of absorption.
[0052] As will be apparent to one skilled in the art, various
modifications can be made within the scope of the aforesaid
description. Such modifications being within the ability of one
skilled in the art form a part of the present invention and are
embraced by the appended claims.
* * * * *