U.S. patent application number 14/167488 was filed with the patent office on 2015-07-30 for process for forming a high loft, nonwoven web exhibiting excellent recovery.
This patent application is currently assigned to BIAX-FIBERFILM. The applicant listed for this patent is BIAX-FIBERFILM. Invention is credited to Douglas B. Brown, Mohammad A. Hassan, Jeffrey D. Stark.
Application Number | 20150211158 14/167488 |
Document ID | / |
Family ID | 53678492 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150211158 |
Kind Code |
A1 |
Hassan; Mohammad A. ; et
al. |
July 30, 2015 |
PROCESS FOR FORMING A HIGH LOFT, NONWOVEN WEB EXHIBITING EXCELLENT
RECOVERY
Abstract
A process for forming a high loft, nonwoven web exhibiting
excellent recovery.
Inventors: |
Hassan; Mohammad A.;
(Neenah, WI) ; Brown; Douglas B.; (Fremont,
WI) ; Stark; Jeffrey D.; (Neenah, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIAX-FIBERFILM |
GREENVILLE |
WI |
US |
|
|
Assignee: |
BIAX-FIBERFILM
GREENVILLE
WI
|
Family ID: |
53678492 |
Appl. No.: |
14/167488 |
Filed: |
January 29, 2014 |
Current U.S.
Class: |
156/167 |
Current CPC
Class: |
D04H 1/74 20130101; D04H
3/16 20130101; D04H 3/02 20130101; D04H 1/559 20130101 |
International
Class: |
D04H 1/559 20060101
D04H001/559; D04H 3/02 20060101 D04H003/02; D04H 5/06 20060101
D04H005/06; D04H 1/56 20060101 D04H001/56; D04H 1/74 20060101
D04H001/74 |
Claims
1. A process for forming a high loft, nonwoven web, comprising the
steps of: a) introducing a molten polymer to a die having a
plurality of nozzles; b) emitting said molten polymer through said
plurality of nozzles to form a plurality of filaments; c) using air
streams to facilitate movement and drawing of said plurality of
filaments; d) directing said filaments towards a pair of moving
surfaces located at a distance of from between about 10 cm to about
150 cm from said plurality of nozzles, and said pair of moving
surfaces forming a convergent passage having an entry and an exit;
e) depositing said plurality of filaments into said entry of said
convergent passage; f) routing said plurality of filaments through
said convergent passage from said entry to said exit and between
said pair of moving surfaces in a machine direction to form a
3-dimensional structure with said filaments transformed into fibers
oriented in the x, y and z directions; and g) bonding said
3-dimensional structure to form a high loft, nonwoven web having a
thickness of less than about 250 millimeters and a basis weight
ranging from between about 50 g/m.sup.2 to about 3,000 g/m.sup.2,
and a vertical cross-section of said high loft, nonwoven web, when
taken parallel to said machine direction, exhibiting a plurality of
snugly stacked, approximately V, U or C-shaped structures, with
each V, U or C-shaped structure having an apex facing in said
machine direction, and said high loft, nonwoven web having a
recovery value ranging from between about 20% to about 99% after
being compressed under a pressure of 0.25 psi for a time period of
30 minutes.
2. The process of claim 1 wherein said 3-dimensional structure is
bonded using thermal bonding, through air bonding, oven bonding,
chemical bonding, wet bonding, mechanical bonding or
hydro-mechanical bonding.
3. The process of claim 1 further comprising adding an additive to
said high loft, nonwoven web downstream of said bonding.
4. The process of claim 4 wherein said additive is a
superabsorbent.
5. The process of claim 1 further comprising spraying an additive
onto said high loft, nonwoven web downstream of said bonding.
6. The process of claim 5 wherein said additive is a fire
retardant.
7. The process of claim 1 further comprising drying said high loft,
nonwoven web downstream of said bonding.
8. The process of claim 1 further comprising cooling said high
loft, nonwoven web downstream of said bonding.
9. The process of claim 8 wherein said high loft, nonwoven web is
cooled to room temperature.
10. A process for forming a high loft, nonwoven web, comprising the
steps of: a) introducing a molten polymer to a die having a
plurality of nozzles; b) emitting said molten polymer through said
plurality of nozzles to form a plurality of filaments; c) using air
streams to facilitate movement and drawing of said plurality of
filaments; d) directing said filaments towards first and second
rotatable drums having a nip formed therebetween, said first and
second rotatable drums located at a distance of from between about
10 cm to about 150 cm from said plurality of nozzles, and said
first and second rotatable drums forming a convergent passage
having an entry and an exit; e) depositing said plurality of
filaments into said entry of said convergent passage; f) routing
said plurality of filaments through said convergent passage from
said entry to said exit and between said nip formed by said first
and second rotatable drums in a machine direction to form a
3-dimensional structure with said filaments transformed into fibers
oriented in the x, y and z directions; and g) thermally bonding
said 3-dimensional structure to form a high loft, nonwoven web
having a thickness of less than about 250 millimeters and a basis
weight ranging from between about 50 g/m.sup.2 to about 3,000
g/m.sup.2, and a vertical cross-section of said high loft, nonwoven
web, when taken parallel to said machine direction, exhibiting a
plurality of snugly stacked, approximately V, U or C-shaped
structures, with each V, U or C-shaped structure having an apex
facing in said machine direction, and said high loft, nonwoven web
having a recovery value ranging from between about 30% to about 95%
after being compressed under a pressure of 0.25 psi for a time
period of 30 minutes.
11. The process of claim 10 further comprising adding an additive
to said high loft, nonwoven web downstream of said bonding.
12. The process of claim 10 further comprising immersing said high
loft, nonwoven web in a liquid solution containing an additive.
13. The process of claim 10 further comprising spraying an additive
onto said high loft, nonwoven web downstream of said bonding.
14. The process of claim 10 further comprising drying said high
loft, nonwoven web downstream of said bonding.
15. The process of claim 10 further comprising cooling said high
loft, nonwoven web downstream of said bonding to room
temperature.
16. A process for forming a high loft, nonwoven web, comprising the
steps of: a) introducing a molten polymer to a die having a
plurality of nozzles; b) emitting said molten polymer through said
plurality of nozzles to form a plurality of filaments; c) using air
streams to facilitate movement and drawing of said plurality of
filaments; d) directing said filaments towards first and second
conveyor belts having an opening formed therebetween, said first
and second conveyor belts located at a distance of from between
about 10 cm to about 150 cm from said plurality of nozzles, and
said first and second conveyor belts forming a convergent passage
having an entry and an exit; e) depositing said plurality of
filaments into said entry of said convergent passage; f) routing
said plurality of filaments through said convergent passage from
said entry to said exit and between said opening formed by said
first and second conveyor belts in a machine direction to form a
3-dimensional structure with said filaments transformed into fibers
oriented in the x, y and z directions; and g) thermally bonding
said 3-dimensional structure to form a high loft, nonwoven web
having a thickness of less than about 250 millimeters and a basis
weight ranging from between about 50 g/m.sup.2 to about 3,000
g/m.sup.2, and a vertical cross-section of said high loft, nonwoven
web, when taken parallel to said machine direction, exhibiting a
plurality of snugly stacked, approximately V, U or C-shaped
structures, with each V, U or C-shaped structure having an apex
facing in said machine direction, and said high loft, nonwoven web
having a recovery value ranging from between about 40% to about 90%
after being compressed under a pressure of 0.25 psi for a time
period of 30 minutes.
17. The process of claim 16 further comprising adding an additive
to said high loft, nonwoven web downstream of said bonding.
18. The process of claim 16 further comprising spraying an additive
onto said high loft, nonwoven web downstream of said bonding.
19. The process of claim 16 further comprising drying said high
loft, nonwoven web downstream of said bonding.
20. The process of claim 16 further comprising cooling said high
loft, nonwoven web downstream of said bonding.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a process for forming a high loft,
nonwoven web exhibiting excellent recovery.
BACKGROUND OF THE INVENTION
[0002] Typically, polymeric fibers, formed by spunbonding,
meltblowing or by some other extrusion process are collected
downstream from an emitter, such as a die with a plurality of
nozzles, on a horizontal oriented conveyor belt. Such processes
tends to produce two-dimensional web where the fibers are oriented
in the x and y directions since they are laid down in a horizontal
plane. There are few if any fibers within the formed web that are
oriented in the z-direction. Because of this, the finished web
tends to lack recovery once it is compressed. This presents an
issue when such finished webs need to be rolled up or stacked for
transport by truck, or rail to a distant manufacturing, or
distribution facility. If the webs are compacted or compressed
during shipment, they lack the ability to recovery to their
original thickness. In addition, once compacted or compressed, such
webs tend to become hard and/or stiff and their pore structure may
become less open. Furthermore, the drapeability of such webs can be
diminished. Functionally, if a compacted or compressed web cannot
recover to approximately its initial loft thickness after shipment,
it can lose some of its thermal and/or acoustical insulation
properties, thereby rendering the material less than desirable for
this purpose.
[0003] Now, a high loft, nonwoven web, exhibiting excellent
recovery, has been invented.
SUMMARY OF THE INVENTION
[0004] Briefly, this invention relates to a process for forming a
high loft, nonwoven web exhibiting excellent recovery.
[0005] The high loft, nonwoven web is a three dimensional structure
with fibers oriented in the x, y and z directions. The web can be
constructed as a single layer or be formed with two or more layers.
The web has a thickness of less than about 250 millimeters and a
basis weight of from between about 50 g/m.sup.2 to about 3,000
g/m.sup.2. The web can be bonded using a thermal bonder, a chemical
bonder, a hydro-mechanical bonder, a mechanical bonder, or be left
unbonded. A vertical cross-section of the web, when taken parallel
to its machine direction, exhibits a plurality of snugly stacked,
approximately V, U, or C-shaped structures, with each approximately
V, U, or C-shaped shaped structure having an apex facing in the
machine direction. The web has a recovery value of from between
about 20% to about 99% after being compressed under a pressure of
0.25 psi for a time period of 30 minutes.
[0006] An apparatus for producing a high loft, nonwoven web having
a three dimensional structure with fibers oriented in the x, y and
z directions is also taught. The apparatus includes a die having a
plurality of nozzles each emitting a filament, and each of the
plurality of nozzles having a distal end. A pair of moving surfaces
is located from between about 10 cm to about 150 cm of the distal
end of each of the plurality of nozzles. The pair of moving
surfaces forms a convergent passage having an entry and an exit.
The apparatus also includes a mechanism for depositing the
plurality of filaments onto and between the pair of moving
surfaces. The plurality of filaments is routed through the
convergent passage in descending travel from the entry to the exit
to form a 3-dimensional structure. The apparatus further includes a
bonder located downstream of and in vertically alignment with the
pair of moving surfaces for bonding the 3-dimensional structure to
create a high loft, nonwoven web with the filaments transformed
into fibers oriented in the x, y and z directions. The web has a
thickness of less than about 250 mm and a basis weight ranging from
between about 50 g/m.sup.2 to about 3,000 g/m.sup.2. A vertical
cross-section of the high loft, nonwoven web, when taken parallel
to its machine direction, exhibits a plurality of snugly stacked,
approximately V, U, or C-shaped structures, with each approximately
V, U, or C-shaped structure having an apex facing in the machine
direction. In other words, the approximately V or U shaped
structure is rotated 90 degrees to a horizontal orientation with
the apex of each facing to the right. The C-shaped structure is
reversed in position so that the apex of each faces to the right.
The high loft, nonwoven web has a recovery value ranging from
between about 20% to about 99% after being compressed under a
pressure of 0.25 psi for a time period of 30 minutes.
[0007] A process for forming a high loft, nonwoven web includes the
steps of introducing a molten polymer to a die having a plurality
of nozzles. Emitting, ejecting or extruding the molten polymer
through the plurality of nozzles to form a plurality of filaments.
Air or gas streams are then used to facilitate downward movement of
the plurality of filaments. The filaments are directed towards a
pair of moving surfaces located at a distance of from between about
10 cm to about 150 cm from the plurality of nozzles. The pair of
moving surfaces forms a convergent passage having an entry and an
exit. The plurality of filaments is deposited into the entry of the
convergent passage. The plurality of filaments is then routed
through the convergent passage in descending travel from the entry
to the exit and between the pair of moving surfaces in a machine
direction to form a 3-dimensional structure with the filaments
transformed into fibers which are oriented in the x, y and z
directions. Lastly, the 3-dimensional structure is bonded to form a
high loft, nonwoven web having a thickness of less than about 250
millimeters and a basis weight ranging from between about 50
g/m.sup.2 to about 3,000 g/m.sup.2. A vertical cross-section of the
high loft, nonwoven web, when taken parallel to its machine
direction, exhibits a plurality of snugly stacked, approximately V,
U, or C-shaped structures, with each approximately V, U, or
C-shaped structure having an apex facing in the machine direction.
The high loft, nonwoven web has a recovery value ranging from
between about 20% to about 99% after being compressed under a
pressure of 0.25 psi for a time period of 30 minutes.
[0008] The general object of this invention is to provide a process
for forming a high loft, nonwoven web exhibiting excellent
recovery. A more specific object of this invention is to provide a
process for forming a high loft, nonwoven web with good thermal
insulation and/or acoustical insulation values.
[0009] Another object of this invention is to provide a process for
forming a high loft, nonwoven web which can be used in the bedding,
upholstery, filtration, foam replacement materials, and products
utilizing cushioning materials.
[0010] A further object of this invention is to provide a process
for forming a high loft, nonwoven web exhibiting from between about
20% to about 99% recovery after compression, and such web exhibits
a high porosity.
[0011] Still another object of this invention is to provide a
process for forming a high loft, nonwoven web exhibiting excellent
recovery such that it can be compactly shipped without losing any
material properties.
[0012] Still further, an object of this invention is to provide a
process for forming a high loft, nonwoven web exhibiting from
between about 40% to about 90% recovery after compression.
[0013] Other objects and advantages of the present invention will
become more apparent to those skilled in the art in view of the
following description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of a high loft, nonwoven web of
this invention showing a plurality of snugly stacked, approximate
V, U or C-shaped structures, with each uniquely shaped structure
having an apex facing in the machine direction of the web.
[0015] FIG. 2 is a schematic of a vertical cross-section of a
section of a high loft, nonwoven web showing a plurality of snugly
stacked, approximate V, U or C-shaped structures, with each
uniquely shaped structure having an apex facing in the machine
direction of the web.
[0016] FIG. 3 is a cross-sectional view of a two layer web.
[0017] FIG. 4 is a cross-sectional view of a multi-layer web.
[0018] FIG. 5 is a perspective view of an alternative embodiment of
a high loft, nonwoven web depicting textured upper and lower
surfaces
[0019] FIG. 6 is a schematic of the textured upper surface of the
high loft, nonwoven web shown in FIG. 4.
[0020] FIG. 7 is a schematic of an apparatus utilizing a pair of
rotatable drums located immediately downstream of a die.
[0021] FIG. 8 is a schematic of an alternative apparatus utilizing
a pair of angled conveyors located immediately downstream of a
die.
[0022] FIG. 9 is a schematic of still another apparatus using a
combination of a spunbond die positioned between first and second
meltblown dies.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Referring to FIGS. 1 and 2, a high loft, nonwoven web 10 is
shown. The high loft, nonwoven web 10 is a 3-dimensional structure
with a plurality of fibers 12 oriented in the x, y and z
directions. In FIG. 1, X-X represents the longitudinal central
axis, Y-Y represents the vertical central axis, and Z-Z represents
the transverse central axis. By `web" it is meant a fabric or
material manufactured in sheet form. By "high loft" it is meant a
low density, fibrous web characterized by a high ratio of thickness
to weight per unit area. The fibers in the web 10 may be continuous
or discontinuous, bonded or unbounded. Desirably, the fibers 12 are
continuous and some of the fibers 12 are bonded. A high loft web
has from between about 5% to about 60% solids by volume. By
"nonwoven" it is meant a web, sheet or batt of natural and/or
man-made fibers or filaments (excluding paper) that have not been
converted into yarns, and that are bonded to each other by thermal,
chemical, mechanical, hydro-mechanical, or by some other means
known to those skilled in the art.
[0024] The high loft, nonwoven web 10 can be formed from a variety
of materials. The high loft, nonwoven web 10 can be formed from
man-made fibers. The fibers can be staple fibers. Typically, the
high loft, nonwoven web 10 is formed from a polymer. The polymer
can be selected from the group consisting of: polyolefins,
polyesters, polyethylene terephthalates, polybutylene
terephthalates, polycyclohexylene dimethylene terephthalates,
polytrimethylene terephthalates, polymethyl methacrylates,
polyamides, nylons, polyacrylics, polystyrenes, polyvinyls,
polytetrafluoroethylenes, ultrahigh molecular weight polyethylenes,
very high molecular weight polyethylenes, high molecular weight
polyethylenes, polyether ether ketones, non-fibrous plasticized
celluloses, polyethylenes, polypropylenes, polybutylenes,
polymethylpentenes, low-density polyethylenes, linear low-density
polyethylenes, high-density polyethylenes, polystyrenes,
acrylonitrile-butadiene-styrenes, styrene-acrylonitriles,
styrene-butadienes, styrene-maleic anhydrides, ethylene vinyl
acetates, ethylene vinyl alcohols, polyvinyl chlorides, cellulose
acetates, cellulose acetate butyrates, plasticized cellulosics,
cellulose propionates, ethyl celluloses, natural fibers, any
derivative thereof, any polymer blend thereof, any copolymer
thereof or any combination thereof. Those skilled in the chemical
arts may know of other polymers that can also be used to form the
high loft, nonwoven web of this invention. It should be understood
that the high loft, nonwoven web 10 of this invention is not
limited to just those polymers identified above.
[0025] The high loft, nonwoven web 10 can be formed or manufactured
using many different kinds and types of equipment and processes.
Some commonly known technology which can be used to form the high
loft, nonwoven web 10 include, but are not limited to: spinning
processes such as meltblowing, spunbond, spunmelt, solution
blowing, electrospinning. In addition, the high loft, nonwoven web
10 can be manufactured by a dry-laid process such as an air-lay
process, a carding process or any combination of any two or more
such processes where fibers are laid down at a nip between two
moving surfaces. The manufactured high loft, nonwoven web 10 can be
bonded or be unbounded. A bonding step adds strength and integrity
to the finished web 10.
[0026] By "spunbond" it is meant a process for producing strong
fibrous nonwovens webs directly from thermoplastic polymers by
attenuating the spun filaments using low temperature, high speed
air while quenching the fibers near the spinnerette face.
Individual fibers are then laid down randomly on a collection belt
and are then conveyed to a bonder. The bonder gives the web
strength and integrity. Fiber size is usually below 250 .mu.m, the
average fiber size is in the range of from between about 10 microns
to about 50 microns and the fibers are very strong compared to
meltblown fibers because of the molecular chain alignment that is
achieved during the attenuating of the crystallized (solidified)
filaments. A typical spunbond die has multiple rows of polymer
nozzle holes. A typical melt flow rate is below about 500 grams/10
minutes.
[0027] By "spunmelt" it is meant a process where fibers are spun
from molten polymers through a plurality of nozzles located in a
die head connected to one or more extruders. A spunmelt process may
include meltblowing and/or spunbonding.
[0028] By "meltblowing" it is meant a process where a plurality of
molten polymer streams are attenuated using an elevated
temperature, high speed gas stream. The gas can be air or other
gases known to those skilled in the art. The attenuated fibers are
then collected on a moving belt, conveyor or a dual drum collector.
Typically, a meltblowing die has around 35 nozzles per inch, a row
of spinnerettes and two inclined air or gas jets for attenuating
the fiber streams. U.S. Pat. No. 4,380,570 and WO 2005/106,085 A1
teach meltblowing processes where multiple rows of polymer nozzles
are surrounded by air nozzles and the streams flowing therefrom are
aligned parallel to one another.
[0029] Still referring to FIGS. 1 and 2, the high loft, nonwoven
web 10 can be constructed as a single layer 14 of material. The
high loft, nonwoven web 10 can be formed using equipment where air
or gas is used to facilitate movement and drawing of the molten
polymer through a plurality of nozzles into a plurality of
filaments. Each of the plurality of filaments is emitted through a
single nozzle.
[0030] Referring to FIGS. 3 and 4, it should be understood that the
high loft, nonwoven web 10' can also be formed of two separate and
distinct layers, 14 and 16, see FIG. 3, or the web 10''can have
multiple layers, see FIG. 4. By "multiple layers" it is meant 3, 4,
5, 6, 7 or more separate and distinct layers. Some of the layers
can be similar and/or identical in composition and characteristics
to another layer, while one or more layers can vary in composition
and/or characteristics from one or more of the remaining layers. In
FIG. 4, three separate and distinct layers 18, 20 and 22 are
present. It should be understood that the web 10, consisting of a
single layer 14, the web 10', consisting of two layers 14 and 16,
or the web 10'', consisting of three layers 18, 20 and 22, can be
bonded to provide strength and integrity.
[0031] In FIG. 3, the web 10' is a two layer embodiment having an
upper layer 14 and a lower layer 16. In FIG. 4, the web 10'' is a
three layer embodiment having an upper layer 18, a middle layer 20
and a lower layer 22. When two or more layers are present in the
finished nonwoven web, it should be understood that each layer can
vary in the type of polymer it is made from. In addition, the
characteristics of a given layer can vary. For example, the
characteristics of one layer can be different from another layer.
The thickness of each layer in the web 10''can vary or be the same.
The density of each layer in the web 10''can also vary or be the
same. The basis weight of each layer in the web 10''can also vary
or be the same.
[0032] Referring again to FIGS. 1 and 2, the high loft, nonwoven
web 10 is depicted as a single layer structure. The high loft,
nonwoven web 10 has a thickness t which can vary in dimensions.
Generally, the thickness t of the high loft, nonwoven web 10 can
range from between about 5 millimeters (mm) to about 300 mm.
Desirably, the thickness t of the high loft, nonwoven web is less
than about 250 millimeters. More desirably, the thickness t of the
high loft, nonwoven web 10 is less than about 200 mm. Even more
desirably, the thickness t of the high loft, nonwoven web 10 is
less than about 100 mm. Most desirably, the thickness t of the high
loft, nonwoven web 10 is less than about 50 mm. When two or more
layers are present in the finished web 10' or 10'', the overall
thickness of the web 10' or 10''can double, triple, etc. depending
upon how many layers are present.
[0033] The high loft, nonwoven web 10 can be formed with different
basis weights. Generally, the basis weight of the high loft,
nonwoven web 10 ranges from between about 50 grams per square meter
(g/m.sup.2) to about 3,000 g/m.sup.2. Desirably, the basis weight
of the high loft, nonwoven web 10 ranges from between about 750
grams per square meter (g/m.sup.2) to about 2,500 g/m.sup.2. More
desirably, the basis weight of the high loft, nonwoven web 10
ranges from between about 100 grams per square meter (g/m.sup.2) to
about 1,000 g/m.sup.2. Even more desirably, the basis weight of the
high loft, nonwoven web 10 is less than about 600 g/m.sup.2.
[0034] The high loft, nonwoven web 10 can also vary in density.
Generally, the high loft, nonwoven web 10 has a density ranging
from between about 10 kilograms per cubic meters (Kg/m.sup.3) to
about 250 Kg/m.sup.3. Desirably, the high loft, nonwoven web 10 has
a density ranging from between about 20 Kg/m.sup.3 to about 200
Kg/m.sup.3. More desirably, the high loft, nonwoven web 10 has a
density ranging from between about 30 Kg/m.sup.3 to about 150
Kg/m.sup.3. Even more desirably, the high loft, nonwoven web 10 has
a density ranging from between about 40 Kg/m.sup.3 to about 100
Kg/m.sup.3.
[0035] The high loft, nonwoven web 10 can be bonded or unbounded.
Desirably, the high loft, nonwoven web 10 is bonded. Bonding
generally imparts strength and integrity to the web 10. Bonding can
be performed using different type of equipment and processes known
to those skilled in the art. Various bonders include: mechanical
bonders such as needle bonding, hydro-mechanical bonders, also
known as wet bonding, thermal bonders, which include through air
bonding and oven thermal bonding and chemical bonding. Whichever
type of bonder is utilized, some of the fibers 12, 14, 16, 18, 20
and 22 are bonded together to make the high loft, nonwoven web 10,
10' and 10''stronger.
[0036] Furthermore, the high loft, nonwoven web 10 can be formed
from polypropylene having a melt flow rate ranging from between
about 4 g/10 min. to about 6,000 g/10 min at a temperature of
230.degree. C. and at a pressure of 2.16 kg according to the
teachings of ASTM D 1238 testing method. Desirably, the high loft,
nonwoven web 10 can be formed from polypropylene having a melt flow
rate ranging from between about 35 g/10 min. to about 2,500 g/10
min at a temperature of 230.degree. C. and at a pressure of 2.16
kg. More desirably, the high loft, nonwoven web 10 can be formed
from polypropylene having a melt flow rate ranging from between
about 500 g/10 min. to about 2,000 g/10 min at a temperature of
230.degree. C. and at a pressure of 2.16 kg. Most desirably, the
high loft, nonwoven web 10 can be formed from polypropylene having
a melt flow rate ranging from between about 500 g/10 min. to about
1,500 g/10 min at a temperature of 230.degree. C. and at a pressure
of 2.16 kg.
[0037] Referring again to FIG. 2, the schematic clearly shows a
vertical cross-section of the high loft, nonwoven web 10 taken
parallel to the machine direction (MD). During formation of the
high loft, nonwoven web 10, the material advances from left to
right. The leading edge of the high loft, nonwoven web 10 is to the
right. The high loft, nonwoven web 10 exhibits a plurality of
snugly stacked, approximately V, U or C-shaped structures 24. These
V, U or C-shaped structures 24 are also depicted in FIG. 1. Each of
the approximately V, U or C-shaped structures 24 has an apex 26
which faces in the machine direction (MD). In other words, the
approximately V or U shaped structure is rotated 90 degrees to a
horizontal orientation with the apex of each facing to the right.
The C-shaped structure is reversed in position so that the apex of
each faces to the right. This unique structure occurs because of
the way the fibers 12 are laid down during formation. This unique
structure is important for it gives the high loft, nonwoven web 10
a very high recovery value. The high loft, nonwoven web has a
recovery value ranging from between about 20% to about 99% after
being compressed under a pressure of 0.25 psi for a time period of
30 minutes, according to the guidelines of the INDA Standard Test
Method (IST 120.2 (01)). Desirably, the high loft, nonwoven web 10
has a recovery value ranging from between about 30% to about 95%
according to the guidelines of the IST 120.2 (01). More desirably,
the high loft, nonwoven web 10 has a recovery value ranging from
between about 40% to about 90% according to the guidelines of the
IST 120.2 (01). Even more desirably, the high loft, nonwoven web 10
has a recovery value ranging from between about 50% to about 80%
according to the guidelines of the IST 120.2 (01).
[0038] It should be understood that each layer of the two layer web
10', shown in FIG. 3, and each layer of the three layered web 10'',
shown in FIG. 4, also exhibits this plurality of snugly stacked,
approximately V, U or C-shaped structures 24 if they are laminated
offline, but they will show one snugly stacked structured,
approximately V, U or C shaped structured, if they are commingled
simultaneously from different spinning heads as shown in FIG. 9.
This kind of commingled high loft structure could have different
fiber size, different polymeric materials, and/or different fiber
cross-section.
[0039] Referring again to FIG. 3, the two layered web 10' has a
three dimensional structure with fibers oriented in the x, y and z
directions. This two layer web 10' has a thickness t.sub.2 of from
between about 5 millimeters to about 500 millimeters and a basis
weight of from between about 50 g/m.sup.2 to about 2,000 g/m.sup.2
The two layered web 10' does not have to be bonded but desirably is
thermally or chemically bonded. Alternatively, the web 10' could be
mechanically or hydro-mechanically bonded. Each of the two layers,
14 and 16, of the web 10' exhibits a vertical cross-section, when
taken parallel to the machine direction (MD) during manufacture of
the two layered web 10', which exhibits a plurality of snugly
stacked, approximately V, U or C-shaped structures 24. Each of the
approximately V, U or C-shaped structures 24 has an apex 26 facing
in the machine direction (MD). In other words, the approximately V
or U shaped structure is rotated 90 degrees to a horizontal
orientation with the apex of each facing to the right. The C-shaped
structure is reversed in position so that the apex of each faces to
the right. The two layered web 10' has a recovery value of from
between about 20% to about 99% after being compressed under a
pressure of 0.25 psi for a time period of 30 minutes according to
the guidelines of the IST 120.2 (01). Desirably, the two layered
web 10' has a recovery value ranging from between about 30% to
about 95% according to the guidelines of the IST 120.2 (01). More
desirably, the two layered web 10' has a recovery value ranging
from between about 40% to about 90% according to the guidelines of
the IST 120.2 (01). Even more desirably, the two layered web 10'
has a recovery value ranging from between about 50% to about 80%
according to the guidelines of the IST 120.2 (01).
[0040] It should be understood that the two layer web 10' can be
formed as two separate layersl4 and 16 from comingled fibrous
materials where each layer has a different fiber size, is formed
from a different material, has different fiber cross-sections, etc.
Furthermore, the two layered web 10' could be laminated to one or
more layers. The additional layers could be a thermoplastic film, a
film, another nonwoven material, paper, cardboard, etc.
[0041] Referring again to FIG. 4, the three layered web 10'' has a
three dimensional structure with fibers oriented in the x, y and z
directions. This three layer web 10'' has a thickness t.sub.2 of
from between about 5 millimeters to about 750 millimeters and a
basis weight of from between about 50 g/m.sup.2 to about 2,000
g/m.sup.2 The three layered web 10'' does not have to be bonded but
desirably is thermally or chemically bonded. Alternatively, the web
10'' could be mechanically or hydro-mechanically bonded. Each of
the three layers, 18, 20 and 22, of the web 10''exhibits a vertical
cross-section, when taken parallel to the machine direction (MD)
during manufacture of the web 10'', which exhibits a plurality of
snugly stacked, approximately V, U or C-shaped structures 24. Each
of the approximately V, U or C-shaped structures 24 has an apex 26
facing in the machine direction (MD). In other words, the
approximately V or U shaped structure is rotated 90 degrees to a
horizontal orientation with the apex of each facing to the right.
The C-shaped structure is reversed in position so that the apex of
each faces to the right. The three layered web 10'' has a recovery
value of from between about 20% to about 99% after being compressed
under a pressure of 0.25 psi for a time period of 30 minutes
according to IST 120.2 (01). Desirably, the three layered web 10
has a recovery value ranging from between about 30% to about 95%
according to IST 120.2 (01). More desirably, the three layered web
10 has a recovery value ranging from between about 40% to about 90%
according to IST 120.2 (01). Even more desirably, the three layered
web 10 has a recovery value ranging from between about 50% to about
80% according to IST 120.2 (01).
[0042] It should also be recognized that an additive can be
incorporated into the high loft, nonwoven web 10, 10' or 10''. The
additive (not shown) can be applied to the high loft, nonwoven web
10, 10' or 10''during manufacture. The additive can be applied in
various ways, including but not limited to: being sprayed on, being
sprinkled on, being extruded, being combined with, being painted
on, being immersed, etc. The additive can be a gas, a liquid, a
solid or a semi-solid. The additive can be selected from the group
consisting of: a superabsorbent, absorbent particles, pulp fibers,
polymers, nanoparticles, abrasive particulars, active particles,
active compounds, ion exchange resins, zeolites, softening agents,
plasticizers, ceramic particles pigments, dyes, flavorants, aromas,
controlled release vesicles, binders, adhesives, tackifiers,
surface modification agents, lubricating agents, emulsifiers,
vitamins, peroxides, antimicrobials, deodorizers, fire retardants,
flame retardants, antifoaming agents, anti-static agents, biocides,
antifungals, degradation agents, stabilizing agents, conductivity
modifying agents, or any combination thereof.
[0043] Referring now to FIGS. 5 and 6, an alternative embodiment of
high loft, nonwoven web 11 is shown having been formed as a single
layer 14 with two major surfaces 28 and 30. The two major surfaces
28 and 30 are aligned opposite to one another. In FIG. 5, the two
major surfaces include the upper surface 28 and the lower surface
30. By "two major surfaces" it is meant the two surfaces of the web
11 which have the greatest surface area. The web 11 has two major
surfaces, 28 and 30, and both of these major surfaces 28 and 30 are
textured. By "textured" it is meant a rough or grainy surface
quality, as opposed to being smooth. The texture can be formed
various ways during processing of the web 11. In FIG. 5, a
plurality of protuberances 32 extends upward from the upper surface
28 and downward from the lower surface 30. By "protuberance" it is
meant a bulge, knob or swelling that protrudes outward.
Alternatively, indentations, cavities or depressions could be
formed in the upper and/or lower surfaces, 28 and 30 respectively,
to obtain a similar textured effect. Desirably, at least one of the
two major surfaces, 28 and 30 of the web 11 is textured. More
desirably, both of the two major surfaces, 28 and 30 of a web 11
are textured.
Apparatus
[0044] Referring to FIG. 7, an apparatus 34 is shown for producing
a high loft, 20o nonwoven web 10, 10', 10'' or 11. The apparatus 34
is shown being oriented in a horizontal configuration, although it
could be arranged vertically or at some other angle relative to the
vertical axis. The high loft, nonwoven web 10, 10', 10'' or 11 has
a three dimensional structure with fibers oriented in the x, y and
z directions. The apparatus 34 includes a die 36 having a plurality
of nozzles 38 each emitting, ejecting or extruding a filament 40.
Each of the plurality of nozzles 38 has a distal end 42. The
apparatus 34 can use air or gas to facilitate movement and drawing
of the molten polymer from the plurality of nozzles 38 into a
plurality of filaments. A pair of moving surfaces, 44 and 46, is
located from between about 10 centimeters (cm) to about 150 cm of
the distal end 42 of each of the plurality of nozzles 38. The pair
of moving surfaces, 44 and 46, can be a first rotatable drum 48 and
a second rotatable drum 50, as is shown in FIG. 7. Alternatively,
the pair of moving surfaces, 44 and 46, can be a first conveyor
belt 52 and a second conveyor belt 54, as is shown in FIG. 8. Other
forms of moving surfaces, 44 and 46, known to those skilled in the
art can also be employed.
[0045] When the pair of moving surfaces, 44 and 46, consists of a
first rotatable drum 48 and a second rotatable drum 50, the first
rotatable drum 48 will have a diameter d.sub.1 and the second
rotatable drum 50 will have a diameter d.sub.2 Desirably, the
diameter d.sub.1 is approximately equal to the diameter d.sub.2.
More desirably, the diameters d.sub.1 and d.sub.2 are identical.
The first and second rotatable drums, 48 and 50 respectively, will
be aligned parallel to one another on the same plane
X.sub.1-X.sub.1. It should be understood that the apparatus 34 is
horizontally oriented so that the filaments 40 will move from left
to right in a machine direction (MD) between the first and second
rotatable drums, 48 and 50 respectively.
[0046] Still referring to FIG. 7, one can see that the first drum
48 rotates counterclockwise while the second drum 50 rotates
clockwise. This specific rotation will cause the plurality of
continuous filaments 40 to move in the machine direction (MD) away
from the plurality of nozzles 38. The speed of the first and second
rotatable drums, 48 and 50 respectively, can vary. Desirably, each
of the first and second rotatable drums, 48 and 50 respectively,
will rotate at the same speed. Alternatively, one of the first and
second rotatable drums, 48 and 50 respectively, could rotate at a
different speed than the other drum and therefore a different
cross-sectional structure may be produced in the machine direction
such as S or S-like shape. The speed of the first and second
rotatable drums, 48 and 50 respectively, should be adjusted
according to the basis weight of the material that is being
produced, the thickness of the desired web 10, the kind of polymer
being extruded, the polymer throughput through the plurality of
nozzles 38, etc.
[0047] The first and second rotatable drums, 48 and 50
respectively, can be operated at room temperature. Alternatively,
the first and second rotatable drums, 48 and 50 respectively, could
be operated at an elevated temperature or at a temperature below
room temperature. Desirably, the first and second rotatable drums,
48 and 50 respectively, are operated at room temperature.
[0048] The first and second rotatable drums, 48 and 50
respectively, can be hollow cylinders with their outer peripheries
covered with a forming wire or screen. The forming wire or screen
can be produced from a variety of different materials known to
those skilled in the art. For example, the forming wire or screen
could be made from a synthetic material, such as polyethylene
terephthalate (PET). Alternatively, the forming wire or screen
could be made from: metal, steel, aluminum, a plastic, a
thermoplastics, etc. The first and second rotatable drums, 48 and
50 respectively, could also be constructed out of various
materials, such as wood, steel, cast iron, aluminum, etc. Another
option is to cover the outer peripheries of the first and second
rotatable drums, 48 and 50 respectively, with metal belts. The
metal belts could be ferrous or non-ferrous. The metal belts could
contain a plurality of apertures, openings or holes arranged in a
predetermined pattern or could be randomly arranged. The size and
shape of the apertures, openings or holes can vary. As is known to
those skilled in the art, each of the first and second rotatable
drums, 48 and 50 respectively, can be equipped with adjustable
vacuum chamber, if desired. Sometimes, it is advantageous to
slightly heat the outer peripheries of the first and second
rotatable drums, 48 and 50 respectively; so that the incoming
filaments 40 will more readily form onto them. The reason for this
is that the open mesh design of a wire, screen or a metal belt
containing apertures, openings or holes can form a specific texture
or pattern onto the outer surfaces of the high loft, nonwoven web
10, 10', 10'' or 11 that is being produced. Such texture or pattern
may enhance the sound insulation and/or thermal absorption
properties of the finished web 10, 10', 10'' or 11. This is an
important attribute when the finished high loft, nonwoven web 10,
10', 10' or 11 is to be used for sound and/or thermal insulation
purposes.
[0049] Still referring to FIG. 7, one will notice that each of the
first and second rotatable drums, 48 and 50 respectively, has a
central axis 56 and 58, respectively. Desirably, each of the
central axes 56 and 58 are aligned on a common vertical plane,
designated X.sub.1-X.sub.1. A horizontal distance measured from the
distal end 42 of each nozzle 38 perpendicular to the vertical plane
X.sub.1-X.sub.1 established a Die-to-Collector Distance (DCD). This
DCD distance can range from between about 10 cm to about 150 cm.
Desirably, the DCD distance is less than about 100 cm. More
desirably, the DCD distance is less than about 90 cm. Even more
desirably, the DCD distance is less than about 80 cm. Most
desirably, the DCD distance is less than about 60 cm. The exact DCD
distance is dependent upon a number of factors including but not
limited to: the melt temperature of the polymer being extruded, the
polymer throughput through the plurality of nozzles 38, etc.
However, it has been found through experimentation, that the closer
the moving surfaces 44 and 46 are located from the distal end 42 of
each of the plurality of nozzles 38, the better the recovery value
of the manufactured high loft, nonwoven web 10, 10', 10'' or 11 is
after compression. When the DCD distance ranges from between about
45 cm to about 75 cm, a high loft, nonwoven web 10, 10', 10'' or 11
can be manufactured with a good recovery value after
compression.
[0050] The outer peripheries of the first and second rotatable
drums, 48 and 50 respectively, are spaced apart from one another
thereby creating a convergence passage 60. By "convergent passage"
it is meant a point of converging, to approach a point. This
converging passage 60 narrows down to a dimension equal to a nip 62
established between the first and second rotatable drums, 48 and 50
respectively. The nip 62 can vary in dimension. The first and
second rotating drums, 48 and 50 respectively, should be mounted
such that the dimension of the nip 62 established therebetween can
be easily adjusted. Generally, the nip 62 can range from between
about 0.5 cm to about 25 cm. Desirably, the nip 62 is greater than
about 0.5 cm. More desirably, the nip 62 ranges from between about
0.5 cm to about 10 cm. Even more desirably, the nip 62 ranges from
between about 0.5 cm to about 8 cm. Most desirably, the nip 62 is
less than about 5 cm.
[0051] The convergent passage 60 has an entry 64 and an exit 66
established by the circumference of the first and second rotatable
drums, 48 and 50 respectively. As the plurality of filaments 40 are
deposited at the entry 64 of the convergent passage 60 they are
directed and routed onto and between the pair of moving surfaces 44
and 46. The routing is facilitated by the rotation of the first and
second rotatable drums, 48 and 50 respectively. The routing causes
the plurality of filaments 40 to pass through the convergent
passage 60 in descending travel from the entry 64 to the exit 66.
The rotational movement of the first and second rotatable drums, 48
and 50 respectively, will cause some of the plurality of filaments
40 to temporarily contact the outer peripheries of the first and
second rotatable drums, 48 and 50 respectively. These filaments 40
will be compressed against the remaining filaments 40 passing
through the nip 62 to create a 3-dimensional structure 68. The
plurality of filaments 40 will be compressed at the nip 62 and this
confined space helps the filaments 40, which are transformed into
fibers 12 as they cool, to be aligned in the x, y and z directions.
By "transformed" it is meant to change markedly the appearance or
form of; to change the nature, function, or condition of; convert.
Thus a 3-dimensional structure 68 is produced instead of a
2-dimensional structure. The 3-dimensional structure 68 usually
will not have a very good recovery value unless fiber-to-fiber
bonds are created using some known bonding process to stabilize the
formed 3-dimensional structure 68.
[0052] Still referring to FIG. 7, the 3-dimensional structure 68 is
advanced in the machine direction (MD) in a horizontal direction.
However, if the apparatus 34 is not horizontally oriented or if
additional support is needed, a conveyor belt 70 can be utilized.
The conveyor belt 70 can be constructed with a screen having a
porous or open pattern to allow heat to pass therethrough freely.
The conveyor belt 70 can move in a given direction over a plurality
of rollers 72. Four rollers 72 are depicted in FIG. 7, although any
number of rollers 72 can be utilized. One of the rollers 72 is the
drive roller and the remaining rollers 72, 72 and 72 are idler or
follower rollers. The conveyor belt 70 makes a continuous loop and
is illustrated moving in a clockwise direction so as to advance the
3-dimensional structure 68 in the downward machine direction
(MD).
[0053] It should be understood that some high loft, nonwoven webs
10 can be formed from certain materials and for certain uses,
wherein bonding is not necessary. However, for most high loft,
nonwoven webs 10, it is advantageous to subject the 3-dimensional
structure 68 to a bonding process. Bonding generally imparts
strength and integrity into the finished web 10. Various bonding
techniques can be utilized. A single bonder or a pair of oppositely
aligned bonders can be utilized.
[0054] Still referring to FIG. 7, a bonder 74 is shown located
downstream of and in vertically alignment with the pair of moving
surfaces 44 and 46 for bonding the 3-dimensional structure 68. The
bonder 74 is located such that the 3-dimensional structure 68
passes therethrough. The bonder 74 can be a thermal bonder, such
as: a through air bonder or an oven bonder. A thermal bonder can
function by creating heat. For example, the heat can be created by
a heated fluid, such as gases or liquid, burning a solid, such as
coal, heating inert gases, using steam, using secondary radiation
from nanoparticles, using infra-red heat, etc. The bonder 74 itself
can include a furnace, an oven, thermoelectric elements, etc., or
any combination thereof. In addition, the bonder 74 can be a
chemical bonder, a mechanical bonder, a hydro-mechanical bonder,
needle bonder, a wet bonder, etc.
[0055] The heat from a thermal bonder will lock some of the fibers
12 to one another in the x, y and z directions. All the fibers 12
do not have to be bonded together, just enough to create the high
loft, nonwoven web 10. The fibers 12 are created as the plurality
of filaments 40 solidify in the 3-dimensional structure 68. By
bonding some of the plurality of fibers 12 together, a high loft,
nonwoven web 10 is create having a thickness of less than about 250
mm, desirably, less than about 200 mm, and more desirably, less
than about 100 mm. The high loft, nonwoven web 10 also has a basis
weight ranging from between about 50 g/m.sup.2 to about 3,000
g/m.sup.2, desirably, from between about 100 g/m.sup.2 to about
2,000 g/m.sup.2, and more desirably, from between about 100
g/m.sup.2 to about 600 g/m.sup.2. Furthermore, a vertical
cross-section of the web 10, when taken parallel to its machine
direction, exhibits a plurality of snugly stacked, approximately V,
U, or C-shaped structures 24. Each of the approximately V, U or
C-shaped structures 24 has an apex 26 facing in the machine
direction. In other words, the approximately V or U shaped
structure is rotated 90 degrees to a horizontal orientation with
the apex of each facing to the right. The C-shaped structure is
reversed in position so that the apex of each faces to the right.
This high loft, nonwoven web 10 has a recovery value ranging from
between about 20% to about 99% after being compressed under a
pressure of 0.25 psi for a time period of 30 minutes, according to
IST 120.2 (01). The IST 120.2 (01) test requires the material to be
compressed under a pressure of 0.25 psi for a time period of 30
minutes. Desirably, the high loft, nonwoven web 10 has a recovery
value ranging from between about 30% to about 95% after being
compressed under a pressure of 0.25 psi for a time period of 30
minutes, according to IST 120.2 (01). More desirably, the high
loft, nonwoven web 10 has a recovery value ranging from between
about 40% to about 90% after being compressed under a pressure of
0.25 psi for a time period of 30 minutes, according to IST 120.2
(01). Most desirably, the high loft, nonwoven web 10 has a recovery
value ranging from between about 50% to about 80% after being
compressed under a pressure of 0.25 psi for a time period of 30
minutes, according to IST 120.2 (01).
[0056] Still referring to FIG. 7, the apparatus 34 may further
include one or more dispensing mechanisms 76 and 78 for adding
chemical binders, or dispensing one or more additives 80 to the
high loft, nonwoven web 10. Two dispensing mechanisms 76 and 78 are
illustrated in FIG. 7. Chemical bonding system can be utilized
instead of the thermal bonding systems. Chemical binders may impart
some new features to the web such as different surface chemistry,
more stiffness or roughness. The exact number of dispensing
mechanisms can vary. Typically, one or two dispensing mechanisms 76
or 78 are utilized to add one or more additives to the high loft,
nonwoven web 10. The additive 80 can be any of those described
above, as well as others known to those skilled in the art.
[0057] It should be understood that the high loft, nonwoven web 10
could also be partially or fully immersed in a liquid solution
containing an additive 80. The liquid solution could be chemically
or electrically charged so as to cause the additive 80 to better
adhere to the high loft, nonwoven web 10.
[0058] Still referring to FIG. 7, the apparatus 34 may also include
a conditioning unit 82 situated downstream from the last dispensing
mechanism 76 or 78. The conditioning unit 82 can vary in design and
function. The conditioning unit 82 could be a dryer that can remove
moisture from the web 10 by utilizing heat or some other process
when the high loft, nonwoven web 10 has to be dried. Alternatively,
the conditioning unit 82 could be a cooler that could blow cool air
onto the high loft, nonwoven web 10 and reduce its temperature.
Still further, the conditioning unit 82 could perform some other
function, for example embossing the web 10, printing the web 10,
combining the high loft, nonwoven web 10 with another layer, etc.
Dryers and coolers are appliances well known to those skilled in
the art.
[0059] Referring now to FIG. 8, another embodiment of an apparatus
34' is depicted wherein the pair of moving surfaces 44 and 46 is
shown as a first conveyor belt 52 and a second conveyor belt 54.
The orientation of the apparatus 34' is vertical although other
orientations could also be employed. The first conveyor belt 52
moves in a counterclockwise direction while the second conveyor
belt 54 moves in a clockwise direction. This arrangement causes the
plurality of filaments 40 emitted, ejected or extruded from the
plurality of nozzles 38 to move vertically downward in a machine
direction (MD). The first and second conveyor belts, 52 and 54
respectively, can run at various speeds. Desirably, the first and
second conveyor belts, 52 and 54 respectively, will run at the same
speed.
[0060] The first and second conveyor belts, 52 and 54 respectively,
converge toward one another at a point located farthest away from
the distal end 42 of each of said plurality of nozzles 38. An
opening 55, equivalent to the nip 62, is present between the first
and second conveyor belts 52 and 54 respectively. The opening 55
occurs and is situated at a plane X.sub.2-X.sub.2. The plane
X.sub.2-X.sub.2 is equivalent to the plane X.sub.1-X.sub.1, shown
in FIG. 7. A vertical distance measured from the distal end 42 of
each nozzle 38 perpendicular to the plane X.sub.2-X.sub.2
established a Die-to-Collector Distance (DCD). This DCD distance
can range from between about 10 cm to about 150 cm. Desirably, the
DCD distance is less than about 100 cm. More desirably, the DCD
distance is less than about 90 cm. Even more desirably, the DCD
distance is less than about 80 cm. Most desirably, the DCD distance
is less than about 60 cm. The exact DCD distance is dependent upon
a number of factors including but not limited to: the melting
temperature of the polymer being extruded, the basis weight of the
material being produced, the polymer throughput through the
plurality of nozzles 38, and the inside diameter of each of the
nozzles, etc.
[0061] As clearly shown in FIG. 8, the first and second conveyor
belts, 52 and 54 respectively, are aligned at an angle alpha
(.alpha.) to one another. The angle .alpha. can vary. Desirably,
the angle .alpha. is less than about 90 degrees. More desirably,
the angle .alpha. is less than about 60 degrees. Even more
desirably, the angle .alpha. is less than about 50 degrees. Most
desirably, the angle .alpha. is less than about 45 degrees. An
angle .alpha. of from between about 15 degrees to about 45 degrees
works well. This orientation creates a convergent passage 60 and a
nip 62. The plurality of filaments 40 are deposited at the entry 64
of the convergent passage 60 as they are directed and routed onto
and between the first and second conveyor belts, 52 and 54
respectively. The routing is facilitates by the movement of the
first and second conveyor belts, 52 and 54 respectively. The
routing causes the plurality of filaments 40 to pass through the
convergent passage 60 in descending travel from the entry 64 to the
exit 66. The movement of the first and second conveyor belts, 52
and 54 respectively, will cause some of the plurality of filaments
40 to temporarily contact the outer peripheries of the first and
second conveyor belts, 52 and 54 respectively. These filaments 40
will be compressed against the remaining filaments 40 passing
through the nip 62 to create a 3-dimensional structure 68. The
plurality of filaments 40 will be compressed at the nip 62 and this
confined space helps the filaments 40, which are transformed into
fibers 12 as they cool, to be aligned in the x, y and z directions.
By "transformed" it is meant to change markedly the appearance or
form of; to change the nature, function, or condition of; convert.
Thus a 3-dimensional structure 68 is produced instead of a
2-dimensional structure. The 3-dimensional structure 68 usually
will not have a very good recovery value unless fiber-to-fiber
bonds are created using some known bonding process to stabilize the
formed 3-dimensional structure 68.
[0062] Still referring to FIG. 8, the apparatus 34' also differs
from the apparatus 34, shown in FIG. 7, in that the 3-dimensional
structure 68 is advanced in a vertical, downward direction until it
contacts a conveyor belt 84. The conveyor belt 84 is positioned
perpendicular to the downward direction of the 3-dimensional
structure 68. The conveyor belt 84 moves through a continuous loop
in a clockwise direction. The conveyor belt 84 causes the
3-dimensional structure 68 to make a 90 degree turn to the right.
This new horizontal, rightward movement is referred to as machine
direction (MD').
[0063] The conveyor belt 84 is mounted on a plurality of rollers
86. Four rollers 86 are depicted in FIG. 8 although any number of
rollers 86 can be utilized. One of the rollers 86 is the drive
roller and the remaining rollers 86, 86 and 86 are idler or
follower rollers.
[0064] It should be understood that some high loft, nonwoven webs
10 can be formed from certain materials and for certain uses,
wherein bonding is not necessary. However, it is advantageous when
producing most nonwoven webs 10 to subject the 3-dimensional
structure 68 to a bonding process. Bonding generally imparts
strength and integrity into the finished web 10. Various bonding
techniques can be utilized. In FIG. 8, a single bonder 74 is
utilized. Upon exiting the bonder 74, a high loft, nonwoven web 10
will be formed. The high loft, nonwoven web 10 has a thickness
t.
[0065] Referring now to FIG. 9, still another apparatus 34'' is
shown which utilized a combination of a first meltblown die 88, a
spunbond die 90 and a second meltblown die 92. The apparatus 34''
is shown being oriented in a vertical configuration, although other
configurations are possible. The spunbond die 90 is positioned
between the first and second meltblown dies, 88 and 92
respectively. This die arrangement produces a commingled, high loft
hybrid nonwoven web that may have different fiber size, different
polymeric materials, and/or different fiber cross-section.
[0066] It should be understood that various combinations can be
obtained using one or more spunbond dies, meltblown dies, spunmelt
dies, etc. When one wishes to manufacture a two layer web 10', as
shown in FIG. 3, two layers can be laminated inline or off-line.
When one wishes to manufacture a three layer web 10', as shown in
FIG. 4, three systems similar to FIG. 7 can be utilized and the
layers can be laminated inline or off-line with another ready-made
web. Each die 88, 90 and 92 will emit, eject, extrude, spin, or
otherwise route a plurality of filaments 40 in a vertical,
horizontal or outward direction. The remaining equipment is similar
to that shown and explained with reference to FIG. 7. One exception
is that the Die-to-Collector Distance (DCD) is calculated by the
distance from the middle spunbond die 90 to the plane
X.sub.1-X.sub.1. Again, this DCD distance can range from between
about 10 cm to about 150 cm. Desirably, the DCD distance is less
than about 100 cm. More desirably, the DCD distance is less than
about 90 cm. Even more desirably, the DCD distance is less than
about 80 cm. Most desirably, the DCD distance is less than about 60
cm. The exact DCD distance is dependent upon a number of factors
including but not limited to: the melt temperature of the polymer
being extruded, the polymer throughput through the plurality of
nozzles 38, etc. However, it has been found through
experimentation, that the closer the moving surfaces 44 and 46 are
located from the distal end 42 of each of the plurality of nozzles
38, the better the recovery value of the manufactured high loft,
nonwoven web 10, 10', 10'' or 11 is after compression. When the DCD
distance ranges from between about 45 cm to about 75 cm, a high
loft, nonwoven web 10, 10', 10'' or 11 can be manufactured with a
good recovery value after compression.
[0067] A 3-dimensional structure 68 emerges from the exit 66 of the
convergent passage 60. As explained above, it may be advantageous
to bond the fibers 12 of the 3-dimensional web 10''together to
increase the strength and improve the integrity of the web 10''. A
bonder 74 is positioned downstream of the first and second
rotatable drums 48 and 50 respectively. The bonder 74 can be any of
the various kinds of bonders explained above. Desirably, the bonder
74 is a thermal or chemical bonder.
[0068] It should be understood that in any of the three apparatuses
34, 34' or 34''described above, that one could add one or more
features to them. For example, one could introduce natural or
synthetic man-made fibers into the high loft, nonwoven web 10, 10',
10'' or 11 during the manufacturing process. Likewise,
non-thermoplastic materials could also be added to the webs 10,
10', 10'' or 11 during manufacture.
[0069] Furthermore, one could spin or extrude multi-component
fibers, fibers having different cross-sectional diameters, use
curly fibers within the webs 10, 10', 10' or 11, or otherwise treat
the fibers 12 is a particular way to obtain a unique finished high
loft, nonwoven web 10, 10'', 10'' or 11.
[0070] It should also be recognized that the various processes,
such as meltblown, spunbond, spunmelt, etc. may require that the
filaments be attenuated at different temperatures, pressures, flow
rates, etc. For example, the process air could be colder or hotter
than the polymer melt.
Process
[0071] The process of forming the high loft, nonwoven web 10, 10',
10'' or 11 will be explains with reference to FIGS. 7-9. The
process includes introducing a molten polymer to a die 36. The die
36 has a plurality of nozzles 38 each having a distal end 42. The
molten polymer is emitted through the plurality of nozzles 38 to
form a plurality of filaments 40. By "emitting" it is meant
extruding, ejecting, spinning, forcing or discharging the molten
polymer under pressure, in any of the known processes described
above and/or known to those skilled in the art. The process also
includes using air or gas streams to facilitate movement and
drawing of the plurality of filaments 30. The filaments 40 are
directed towards a pair of moving surfaces 44 and 46, located at a
distance of from between about 10 cm to about 150 cm from the
plurality of nozzles 38. The pair of moving surfaces 44 and 46 can
be first and second rotatable drums, 48 and 50 respectively, or can
be first and second conveyor belts, 52 and 54 respectively.
[0072] The pair of moving surfaces 44 and 46 forms a convergent
passage 60 having an entry 64 and an exit 66. The plurality of
filaments 40 are deposited into the entry 64 of the convergent
passage 60. The plurality of filaments 40 are then routed through
the convergent passage 60 in descending travel from the entry 64 to
the exit 66 and between the pair of moving surfaces 44 and 46 in a
machine direction to form a 3-dimensional structure 68. In the
3-dimensional structure 68, the filaments 40 are transformed upon
cooling into fibers 12 oriented in the x, y and z directions. The
process further includes bonding the 3-dimensional structure 68 to
form a high loft, nonwoven web 10, 10', 10'' or 11 having a
thickness t, t.sub.1 or t.sub.2 of less than about 250 millimeters
and a basis weight ranging from between about 50 g/m.sup.2 to about
3,000 g/m.sup.2. The 3-dimensional structure 68 can be bonded using
a variety of different bonders. Some bonders which can be used
include but are not limited to: thermal bonding, through air
bonding, oven bonding, chemical bonding, wet bonding, mechanical
bonding or hydro-mechanical bonding.
[0073] A vertical cross-section of the high loft, nonwoven web 10,
10', 10'' or 11, when taken parallel to the machine direction (MD),
exhibits a plurality of snugly stacked, approximately V, U or
C-shaped structures 24. Each of the approximately V, U or C-shaped
structure 24 has an apex 26 facing in the machine direction (MD).
In other words, the approximately V or U shaped structure is
rotated 90 degrees to a horizontal orientation with the apex of
each facing to the right. The C-shaped structure is reversed in
position so that the apex of each faces to the right. The high
loft, nonwoven web 10, 10', 10'' or 11 has a recovery value ranging
from between about 20% to about 99% after being compressed under a
pressure of 0.25 psi for a time period of 30 minutes.
[0074] Referring again to FIGS. 3, 4 and 9, it is possible to
utilize two separate and distinct dies 36 and 36 to produce a two
layered web 10', see FIG. 3. One could also utilize three separate
and distinct dies 36, 36 and 36 to produce a three layered web
10'', see FIG. 4. Likewise, one could utilize four or more separate
and distinct dies, 36, 36, 36 and 36 to produce a multi-layered web
having 4 or more layers. Structure in these hybrid nonwoven high
loft materials of the comingled fibers or the laminated layers may
have different fiber size, different polymeric materials, and/or
different fiber cross-section.
[0075] It should be understood that an additive 80 can be added to
the high loft, nonwoven web 10, 10', 10'' or 11 downstream of the
bonder 74. The additive 80 can be any of those mentioned above. The
additive 80 can be deposited onto the high loft, nonwoven web 10,
10', 10'' or 11, or it could be sprayed thereon. Alternatively, the
high loft, nonwoven web 10, 10', 10'' or 11 could be immersed in a
liquid solution containing an additive 80.
[0076] It should also be understood that the high loft, nonwoven
web 10, 10', 10'' or 11 can be dried downstream of the bonder 74.
Likewise, the high loft, nonwoven web 10, 10', 10'' or 11 could be
cooled downstream of the bonder 74. Such cooling could reduce the
temperature of the high loft, nonwoven web 10, 10', 10'' or 11 to
room temperature or thereabout.
[0077] Experiments:
1. Meltblowing Unit
[0078] A number of high loft, nonwovens sample webs were produced
using a meltblowing pilot line that had a 381 mm meltblowing die
with multi-row spinnerettes known as the Biax meltblowing (MB) die.
This die is commercially available from Biax-Fiberfilm Corporation
having an office at N992 Quality Drive, Suite B, Greenville, Wis.
54942. The meltblowing spinnerettes had 242 polymer nozzles. The
inside diameter of each spinnerette was 0.508 millimeters (mm)
while the outside diameter of each spinnerette was 0.711 mm. Each
polymer nozzle was surrounded by an air nozzle where the blowing
air was coming from the annular space between the polymer nozzle
and the air nozzle. The diameter of each of the air nozzles was 1.4
mm. The Biax meltblowing (MB) die design is taught in U.S. Pat. No.
5,476,616 and U.S. Patent Publication 2005/0056956 A1. Typical
commercial Biax meltblowing (MB) dies have from between about 6,000
to about 11,000 nozzles per meter.
2. Process Conditions
[0079] Several examples of high loft, nonwoven webs were made using
the pilot meltblowing line to prove the concept of this invention.
It should be understood that the high loft, nonwoven webs could
also have been made using spunbond equipment. Furthermore, it
should be understood that the exact process conditions used to make
these samples could be changed. Any variation of the process
conditions, such as air temperature, polymer chemistry or type,
polymer melt temperature, polymer throughput, air throughput, etc.
could be changed.
[0080] The first seven (7) nonwoven web samples were made of
polypropylene that was provided by Exxon-Mobil under the trade
name: ACHIEVE 6936G1. This polypropylene had a typical melt flow
rate of 1,550 grams per 10 minutes (according to ASTM test D 1238,
230.degree. C., 2.16 kg). The last two (2) nonwoven web samples
(samples 8 and 9) were made of polylactic acid that was provided by
Natureworks under the trade name: INGEO PLA 6202D. The polylactic
acid had a melt flow rate of 15 grams (g) to 30 g per 10 minutes
(according to ASTM test D 1238, 210.degree. C., 2.16 kg).
[0081] Polypropylene samples were fabricated at the following
process conditions:
[0082] Polymer melt temperature: 190.degree. C.
[0083] Air temperature: 170.degree. C.
[0084] Polymer throughput: 0.26 g/hole/minute
[0085] Air pressure: 35 KPa
[0086] The basis weight of these samples varied from between about
150 g/m.sup.2 to 500 g/m.sup.2 by varying the speed of the first
and second rotatable drums or by varying the speed of the first and
second conveyor belts. The Die to Collector Distance (DCD) varied
between about 30 centimeters (cm) to about 45 cm.
[0087] Polylactic acid samples were made at the following process
conditions;
[0088] Polymer melt temperature: 260.degree. C.
[0089] Air temperature: 260.degree. C.
[0090] Polymer throughput: 1 g/hole/minute
[0091] Air pressure: 35 KPa
[0092] The basis weight was around 500 g/m.sup.2 and the
Die-to-Collector Distance (DCD) was around 75 cm.
[0093] Some of the samples were thermally bonded using an infra-red
oven at a temperature of 120.degree. C. and the dwell time (contact
time) was about 3 seconds to about 5 seconds.
3. Characterization Tests
3.1 Basis Weight
[0094] Basis weight is defined as the mass per unit area and it can
be measured in grams per meter squared (g/m.sup.2). The basis
weight test is done according the INDA standard IST 130.1 which is
equivalent to the ASTM standard ASTM D3776. Ten (10) different
samples were die cut from different locations in a larger sample
web and each one had an individual area equal to 100 cm.sup.2. The
weight of each replicate was measured using a sensitive balance
within .+-.0.1% of weight on the balance. The basis weight in
grams/m.sup.2 was measured by multiplying the average weight by
100.
3.2 Thickness of the High Loft Nonwoven
[0095] Thickness is defined as the distance between one surface and
an opposite surface of a single web measured under a specified
pressure. For high loft, nonwoven webs, the thickness was measured
according the INDA standard IST 120.2 (01). The apparatus include a
thickness testing instrument that had: an anvil, a presser foot,
and a scale indicating the distance between these two parallel
plates. The foot presser was 305 mm.times.305 mm (12
inches.times.12 inches) in size and had a weight of 288 grams. Five
representative specimens of the fabric were die cut and tested in
the standard atmosphere for testing as prescribed in ASTM D1776.
Samples were handled carefully to avoid altering the natural state
of the fabric. Each specimen was placed on the bottom plate and the
presser foot was placed with care on the top of the sample. The
average thickness of these specimens is reported along with a
standard deviation.
3.3 Compression and Recovery of the High Loft Nonwovens
[0096] In this test, one measures the compression and recovery
performance of the high loft, nonwoven web samples by observing the
linear distance that a movable plane is displaced from a parallel
surface by the high loft, nonwoven web samples while under a
specified pressure. After a specified time interval, the pressure
is removed and the recovery of the linear distance is measured. The
performance of the high loft, nonwoven webs for use in furniture,
clothing, and insulation applications (acoustic or thermal) may be
estimated from these compression and recovery values. The original
thickness T1, measured in millimeters (mm), was measured according
to the IST 120.2 (01). The presser foot was raised and the 288 gram
weight was replaced with 16.33 Kg (36 pounds) to provide a pressure
of 1720 Pa (0.25 psi). The presser foot with the new weight was
placed on top of the high loft, nonwoven webs samples for 30
minutes and then the compressed thickness T2 was measured. Finally,
the presser foot was raised and replaced by the 36 pound weight
with the 288 gram weight. After five (5) minutes, the presser foot
was lowered to measure the thickness recovered, T3.
Percent compression=[(T1-T2)/T].times.100
Percent Recovery=[T3/T1].times.100
Example 1
[0097] In this example, the effects of the collector type on the
high loft, nonwoven web properties were looked at. Sample 1 and 2
showed a big difference in thickness or caliper of the nonwoven
web. The big difference is mainly due to collecting the spun fibers
on a flat belt versus collecting them between two rotating drums
having a nip gap of 2.5 cm. The dual drum collection system
increased the thickness by 1,500% although both samples have the
same mass per unit area. Sample 3 showed that by thermally bonding
the high loft, nonwoven sample #2, one could enhance the recovery
properties by 26%. Such enhancement will greatly increase the
thermal insulation and acoustical properties of a web. With the
proper tuning of the fiber formation conditions and the bonding
conditions, the compression and recovery properties can be greatly
enhanced, see Table 1 below.
TABLE-US-00001 TABLE 1 Table (1): Effect of Collector type on
polypropylene high loft nonwoven samples Nip Basis Percent Percent
DCD, Collector gap, weight, Thickness, compression Recovery Sample
(cm) type (cm) Bonding (g/m.sup.2) (mm) (%) (%) # 1 45 flat belt NA
No 150.7 0.81 NA NA # 2 45 dual 2.5 No 147.8 13.6 72 53.6 drum # 3
45 dual 2.5 Thermally 142.6 12.6 72.4 67.7 drum Bonded
Example 2
[0098] In this example, the effect of the Die-to-Collector Distance
(DCD) on the compression-recovery properties of the high loft
nonwoven web samples were looked at. The meltblown filaments were
collected at a distance close to the die, where they are very
tacky. This action created fiber to fiber bonding in the high loft,
nonwoven web samples between the first and second rotatable drums
and avoided the need for additional downstream bonding. This might
work on equipment operating at a low polymer throughput to produce
a high loft, nonwoven web with a basis weight of less than about
150 g/m.sup.2. However, when the polymer throughput and the basis
weight increases, the blowing air causes the filaments to fly
around and they prevent being captured on the first and second
rotatable drums because of the difficult air management at a closer
Die-to-Collector Distance (DCD). Samples 2 and 3 were collector at
a DCD distance of 45 cm from the die face. Samples 4 and 5 were
collected at a DCD distance of 30 cm from the die face. As shown in
Table 2, collecting the fibers at a closer DCD distance, as in
sample 4, enhanced the fiber to fiber bonding and achieved similar
recovery performance to sample 3, which was thermally bonded.
Sample 5 was obtained by oven bonding sample #4. However, it was
found that this additional bonding actually decreased the recovery
properties of sample 5 by 28% because the additional bonding
actually caused the fibers to become brittle.
TABLE-US-00002 TABLE 2 Table (2): Effect of Die-to-collector
distance on polypropylene high loft nonwovens Nip Basis Percent
Percent DCD, Collector gap, weight, Thickness, Compression Recovery
Sample (cm) type (cm) Bonding (g/m.sup.2) (mm) (%) (%) # 2 45 dual
2.5 No 147.8 13.6 72.3 53.6 drum # 3 45 dual 2.5 Thermally 142.6
12.6 72.4 67.7 drum Bonded # 4 30 dual 2.5 No 146.5 13.5 73.3 65.6
drum # 5 30 dual 2.5 Thermally 151.25 19.8 81.7 47.7 drum
Bonded
Example 3
[0099] In this example, the effect that basis weight had on the
compression-recovery properties of the high loft, nonwoven web
samples were looked at. As shown in Table 3, by increasing the mass
per unit area, the compressibility decreased which is obvious
because of the larger nonwoven mass passing between the nip of the
first and second rotatable drums. It was also noticed that by
increasing the basis weight, the percent recovery after compression
also increased, which may be due to the larger number of
fiber-to-fiber bonds that were created. Collecting the fibers of
samples 6 and 7 at a closer Die-to-Collector Distance (DCD) was not
successful on the pilot scale because of the difficult air
management and the larger mass of filaments that blocked the way in
front the blowing attenuation air.
TABLE-US-00003 TABLE 3 Table (3): Effect of Basis Weight on
polypropylene high loft nonwovens Nip Basis Percent Percent DCD,
Collector gap, weight, Thickness, compression Recovery Sample (cm)
type (cm) Bonding (g/m.sup.2) (mm) (%) (%) # 3 45 dual 2.5 Through
142.6 12.6 72.4 67.7 drum Bonded # 6 45 dual 2.5 Through 302.3 17.8
66.9 75.9 drum Bonded # 7 45 dual 2.5 Through 492.6 23.2 61.7 80.8
drum Bonded
Example 4
[0100] In this example, the concept of collecting spunmelt fibers
at the nip formed between two rotating drums, for different
polymers, were looked at. Sample 8 and 9 were produced using
polylactic acid resin. Despite the spinning difficulty of such
polymer and the shrinkage effect that accompanied the web
formation, two high loft, nonwoven samples were collected. As shown
in Table 4, sample 8, which was not thermally bonded, had higher
compressibility but lower recovery properties than sample 9 which
was thermally bonded using the infra-red thermal oven. Sample 9 was
also stronger than sample 8 during handling and had a better
structure integrity as sample 9 was not falling apart because of
the fiber-to-fiber bonds that were created during the post heat
treatment. It is well known that structural integrity of the loose
fibers can be enhanced by using other bonding techniques, such as
through air bonding or chemical bonding.
TABLE-US-00004 TABLE 4 Table (4): PLA high loft nonwovens Nip Basis
Percent Percent DCD, Collector gap, weight, Thickness, compression
Recovery Sample (cm) type (cm) Bonding (g/m.sup.2) (mm) (%) (%) # 8
75 dual 2.5 No 530 20.5 44.7 80.2 drum # 9 75 dual 2.5 Through 533
19.1 33.5 85.7 drum Bonded
[0101] While the invention has been described in conjunction with
several specific embodiments, it is to be understood that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, this invention is intended to embrace all such
alternatives, modifications and variations which fall within the
spirit and scope of the appended claims.
* * * * *