Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Jo KIWI
_ METHOD AN APPARATUS FOR THE PRODUCTION OF A FUSED NON WOVEN FABRIC
Background of the Invention
The invention relates to a non woven fabric, method and
apparatus for producing the non woven fabric.
In the last twenty-five years or so the development ox
polymeric materials has seen a tremendous growth. Polymeric materials
lend themselves to a vast number of uses and application. One of the
more significant areas in which polymeric materials have been used is in
the textile industry. The melt spinning of thermoplastic synthetic
materials to produce continuous filaments, staple and yarns of such
materials has revolutionized the textile industry.
Although much of the growth in the use of synthetic filaments
has been in the use of knitted or woven fabrics, non woven materials of
synthetic Eliminates also have experienced substantial growth. There are
a number of methods known today for producing non woven fabrics from
synthetic filaments and mixtures of natural and synthetic filaments.
Non woven fabrics find a variety of uses. A specific area in which
non woven fabrics have gained acceptance is in the manufacture of carpets.
Slice non woven fabrics made of synthetic fixers resist deterioration
caused by mildew, synthetic non woven fabrics are used for the backing
material in carpets and such carpets are excellent for use in areas
exposed to moisture, such as patios and other outdoor areas.
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Non woven fabrics are used in many other areas as well. For example
non woven fabrics both fused and unfused are used as substrates in the product
lion of various laminates and as ticking material in the furniture industry.
Although nonwovens are presently used in a variety of applications as indicated
above, there is still a need to improve non woven fabrics especially with
regard to -their dimensional stability and strength.
Some of the non woven fabrics known in the art are those produced by
needling fibers together employing at least one needle loom. The surface
first penetrated by the needles o-f the needle loom is often referred to as
the "face side" of the fabric and the "face side" of the fabric generally has
a much smoother surface as compared to the opposite side of the fabric which
is generally referred to as the "back side" of the fabric. As used herein
the terms "face side" of the fabric and "back side" of the fabric are intended
to refer to the respective surfaces described above.
In a number of applications it is desirable for a needle punched
non woven fabric to have a substantial portion of the fibers forming the face
snide of the fabric fused together and to have a substantial portion of the
fibers forming the back side of the fabric unfused so as to form a fuzzy or
nap-Like surface, frequently referred to as a beard. Also it is desirable to
produce non woven fabric with the face side essentially fused and the back
sLdc essentially unused and having a "beard" which has a slower elongation
and/or higher ultimate strength as compared to comparable prior art fabrics.
It is an object of the present invention to produce a norlwoven
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I Another object of the invention is to produce a fused non woven
fabric with improved dimensional stability and strength as compared to fused
non woven fabrics known in the art.
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Another object of the present invention it to provide a fused
non woven fabric produced from thermoplastic staple fibers having the fibers
in the back side of the fabric substantially unfused to form a "beard" and
having a higher ultimate strength and/or lower elongation in comparison to
S other comparable non woven fabrics known in the art.
Other objects, aspects and advantages of the invention will be
apparent after studying the specification, drawing and the appended claims.
Summary
cording to the invention a fused non woven fabric of thermoplastic
fibers having a first surface and a second surface opposite the first surface
is produced by exposing at least one of the first and second surfaces of the
fabric to infrared radiation to the extent that a substantial portion of the
fibers of the at least one surface is fused together and contacting at least
one of the first and second surfaces of the fabric with at least one heated
roll having a temperature sufficient to fuse together at least a portion of
the fibers of the surface in contact with the heated roll. In one aspect of
applicant's invention a fused fabric of thermoplastic staple fibers is produced
having a lower elongation and/or a higher ultimate strength, particularly
when the back side of the fabric is unfused, as compared to comparable prior
art non woven fabrics.
Fllrther according to the invention apparatus is provided comprising,
infrared fusion means being suitable for exposing the fibers of at least one
~ur~flce ox a non woven fabric having a first surface and a second surface
opposite said first surface and fusing together at least a portion of said
fibers; and at least one heated roll being suitable for contacting a-t least
one of said first and second surfaces of said fabric, and fusing together the
fibers of the surface in con-tact with the heated roll.
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Brief Description of the Drawing
To further describe the invention the attached drawing is provided
in which:
FIGURE 1 is a top view of the schematic representation of an
embodiment of the apparatus of the invention including apparatus suitable for
producing an unfused non woven fabric; and
FIGURE 2 is an elevation Al view of the apparatus of FIGURE 1.
Detailed Description of the Invention
The present invention is primarily based upon the discovery that an
improved fused non woven fabric is produced when an unfused fabric is subjected
to fusion temperatures employing infrared radiation and at least one heated
roll. If the same unfused non woven fabric is fused by subjecting the fabric
to Elusion temperatures employing only infrared radiation or only at least one
heat roll, then the fused fabric generally has a higher elongation and/or
lower ultimate strength. Prior to the present invention it was known that
roll Elusion of a fabric primarily fused the surface of -the fabric and that
the fibers on or near the fused surface were flattened which destroyed the
fibers' cross section and weakened the fibers. also prior to the invention
it was known that infrared radiation of a fabric not only fused the fibers on
or ne~flr the surface exposed to the infrared radiation, but that infrared
radiation flossed fibers in the contra]. portion of the fabric and even eyebrows
on the Ursa opposite the surface exposed to the infrared radiation. It
was known prior to the present invention that an infrared fused fabric
generally had a lower elongation and/or a higher ultimate strength as compared
to a comparable roll fused fabric. Thus it was surprising to discover that a
fabric exposed to infrared radiation and roll fused generally has a lower
elongation and/or higher ultimate strength as compared to a comparable infrared
fused or roll reused Fabric
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In a preferred embodiment of the invention staple fibers positioned
on the back side of a fabric are substantially unfused and a substantial
portion of the staple fibers positioned on the face side of the fabric an-l
between the face side and the back side of the fabric are fused. In order to
achieve a fabric described in the preferred embodiment, it was surprisingly
found that the combination of infrared fusion and roll fusion in accordance
with the present invention must be used in order to produce a fused fabric
with the highest ultimate strength and/or the lowest elongation possible.
While it is not essential except in the preferred embodiment of the
I invention, it is generally desirable to expose the fabric to infrared radiation
first and subsequently to contact the fabric with a heated roll. Hun the
fabric is contacted with the heated roll, the fusion that takes place is
essential on the surface and the fibers on or near the surface are flattened
so that when that surface is subsequently subjected to infrared radiation the
flattened fibers tend to reduce penetration of the infrared radiation.
Non woven fabrics suitable for use in the invention can be almost
any unfused non woven fabrics produced from -the thermoplastic fibers. In -the
preferred embodiments of the invention the thermoplastic fibers are staple
giber and tile non woven fabric is needle punched. Generally the non woven
fabric employed has a weight within the range of about 2 oozed to about 20
oozed ; however, the weight of the fabric employed is more often within the
Rutledge of about 2.5 oozed to about 4.5 oozed.
[n order to more fully understand the present invention FIGURES 1
and 2 are provided which include apparatus in accordance with applicant's
invention and apparatus for producing a non woven fabric suitable for use in
the invention. Referring to FIGURES 1 and 2 a batt-forming means is shown
comprising two web forming trains A and A' in which feed means 10,10' such as
bale breakers, blender boxes, feed boxes, etc., feed fibers in the form of
staple such as polypropylene staple, to carding machines 12,12'. The carding
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machines l2,12' produce carded webs 14,14' of fibers which are picked up by
the takeoff aprons 16,l6' of cross lappers 20,20'. Cross lappers 20,20' also
comprise lapper aprons 18,18' which traverse a carrier means such as floor
apron 38, in a reciprocating motion laying the webs 14,14' to form a belt 36
on the floor apron 38.
The carded webs llt,l4~ are laid on floor apron 38 to build up
several thicknesses to produce belt 36. The fibers forming belt 36 are
oriented primarily in the fill direction, that is, a direction perpendicular
or normal to the direction of movement of belt 36 positioned on floor apron 38.
Two web-forming trains A and A' or more are used to increase the speed of the
overall operation; however, one such web-forming train can be employed.
As used throughout the specification and claims, the term "fill
direction" means the direction transverse to -the direction owe movement of
boil 36 on floor apron 38. The term "warp direction" means the direction
puerilely. to the direction owe movement of belt 36 on floor apron 38.
A first drafting means 40, comprising at least two sets of nip
rolls or an inlet apron 42 and one set of nip rolls 44, is used to draft
belt 36. As used herein the terms stretching, drawing and drafting are
synonymous. no FIGIJRES 1 and 2 the first drafting means comprises five sets
of nip rolls 44, 46, I 50 and 52 and inlet apron 42 and outlet apron 54.
Each set ox nip rolls -is shown as one over-two configuration, which works
very well, but almost any arrangement can be used, such as a one-over-one,
tavern, etc., as well as mixtures of nip roll configurations. The
crafted belt 56 then is passed -to needle loom 58 wherein the belt is needled
at a density in the range of 100 -to 1000 punches per square inch and at a
needle penetration in the range owe from about 1/4 inch to about 3/4 inch.
One or more needle looms can be used. The needle looms can be either single
needle board or a double needle board looms.
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The drafted, needled belt 60 is again drafter in the warp direction
by a second drafting means 62 comprising at least two sets of nip rolls 64
and 66 or an inlet apron and one set of nip rolls (not shown. The needled
belt 68 which was drafted in the warp direction both before and after needling
is passed under roll 70 to a third drafting means, such as tinter frame 72
which drafts needled Betty 68 in the fill direction to produce belt 75. As
shown clearly in FIGURE 2, tinter frame 72 comprises a fill-drafting means 74
and a tensioning means 76. Tensioning means 76 is not used to draft belt 77,
but to subject belt 77 to tension in the fill direction.
Infrared heating means 80 and 82 are shown on opposite sides of the
unfused belt or fabric. Infrared heating means 82 is positioned to expose
the face side of fabric 77 to infrared radiation sufficient to fuse together
at least a portion of the fibers on the face side and infrared heating means 80
is positioned to expose the back side of fabric 77 to infrared radiation
sufficient to fuse together at least a portion of the -fibers on the back
side. While only one infrared heating means is shown on each side of fabric 77
two or more infrared heating means can be employed on either or both sides of
fabric 77 if desired.
Subsequent to tensioning means 76 are two rolls 86 and 88 wherein
at least one of said rolls is heated to a temperature sufficient to fuse
together a portion of the fibers of the surface of Fabric I lore than one
hotly roll can be employed pharaoh either our both slides of the fabric, if desired;
however, Kit is generally sufficient to piston one not]. which can be heated
to the desired temperature on the face side of fabric 84, such as roll 88,
US and one roll which can be heated -to the desired temperature on the back side
out fabric 84, such as roll 86.
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In an optional embodiment of the apparatus of the invention a
second tensioning means 102 and associated infrared fusion means 104 and 106
can be used in order to subject the fabric 84 to infrared radiation subsequent
to fusion of the fibers of the fabric with heated rolls; however, it is
emphasized that this additional equipment is optional and such equipment is
only needed when it is desired to fuse -the fabric with infrared radiation
after the fabric is roll fused. When infrared fusion means 104 and 106 are
employed, infrared fusion means 80 and 82 and tensioning section 76 generally
are not required although tensioning means 76 is recommended in order to
stabilize fabric 75 exiting drafting means 74.
The fabric 90 exiting rolls 86 and 88 and tensioning means 102, if
fused, passes over idler rolls 90 and 94 and is rolled up over windup rolls 98
and 100, at least one of which is driven by a suitable power means (not
shown) to produce a roll of fused fabric 96.
lo In the operation of the apparatus shown in FIGURES 1 and 2 synthetic
thermoplastic fibers in the form of staple are passed from feed means 10,10'
to carding machines 12,12' to produce carded webs 14,14'. The carded webs
14,14' are picked up by takeoff aprons 16,16' of cross lappers 20,20'. Lapper
aprons 18,18' lay the carded webs on floor apron 38 to produce belt 36. The
member of webs used to form belt 36 depends upon a number of variables, such
as the desired weight of the belt, the wow of the webs, the amount the
belt it drafted during the process, etc. Tile belt 36 is then drafted in the
warp direction by suitable mean, such as the five sets of nip rolls 44, 46,
48, So and 52. When using nip rolls only two sets of nip rolls actually are
required to draft the belt; however, the use of more than two sets of nip
rolls, such as the five nip rolls shown, provides a more uniform drafting
since between any set of nip rolls a smaller drafting ratio can be used and
still obtain the overall desired drafting ratio. In addition, the belt is
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so
frequently drafted between the nip formed by the feed apron and the first set
o-f nip rolls 44. The belt 36 is drafted because each set of nip rolls is
operated at a successively higher speed than the speed of the preceding inlet
apron or set of nip rolls. Generally it has been found that utilization of
more sets of nip rolls and smaller draft ratios between each set of nip rolls
produces a more uniform fabric than utilization of fewer sets of nip rolls
with higher draft ratios; however, at some point additional sets of nip rolls
with reduced draft ratios between each set of nip rolls will not improve the
product. In addition, there is a maximum speed at which -the Betty a-t a given
weight can be produced due to the limitations of the batt-forming equipment.
Thus, as in almost any process, the most economical operation requires
consideration of a number of variables, and in particular the various parameters
of the material processed. For example, some of the variables of the processed
material which affect the drafting process are staple polymer, staple length
lo and deifier, staple finish degree of crimp, weight of the belt, etc. Goner-
fly trot about 2 to about 6 sets of nip rolls are utilized with an overall
draft ratio within a range of about Lyle to about 4 and a maximum draft ratio
between sets of nip rolls of 2. Louvre, a very good product is produced
utilizing from about 3 to 5 sets of nip rolls with an overall draft ratio
I Whitney a rarlge of about 1.2 to 1.8 and a maximum draft ratio between sets of
nip rolls of 1.3.
The drained 'belt So is theft passed to needle 'Loom 58 wherein the
but is needled to make a more coherent material. us stated above, one or
more needle looms can be used and in addition each needle loom can be a
double board needle loom. It is noted that the belt will experience some
drafting as it passes through the needle loom which must be taken into concede-
oration in determining the operating speeds of equipment positioned subsequent
to the needle loom. It is not uncommon to experience drafting at a ratio in
to
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the range of from about 1.3 to about 2, employing one single board needle
loom or one double board needle loom. The larger drafting ratios in the
above range are normally experienced using a double needle board loom.
The drafted, needle belt is again drafted in the warp direction in
S a second drafting means 62, such as employing nip roils 64 and 66, and
operating the speed of nip rolls 66 at a slightly higher speed than nip
rolls 64. The draft ratio employed in the second drafting zone is also
selected depending upon the material processed. Generally the draft ratio in
the second drafting zone is within a range of about 1.01 to about 2; however,
a good product is produced utilizing a draft ratio within a range of about
1.3 to about 1.5.
Needled belt 68 which has been drafted in the warp direction both
before and after needling is then passed to a third drafting zone, indicated
by tinter frame I which drafts the belt in the fill direction through the
use of diverging tracks 73 which grasp the fabric at the inlet and draft the
fabric as the tracks slowly diverge from one another. The fill-drafting
ratio depends upon a number of variables, such as staple length, denier, belt
weight, needle density, etc. Generally the fill-drafting ratio is within a
range of about 1.01 to about 1.5; however, a fill-drafting ratio within a
I rllllge of ablate lo two about 1.3 produces a good product. In one aspect of
the Lnvent:Lon tinter frame 72 contains a tensioning means 76 which applies
tension to the fabric yin at least the filial direction 78 while the fabric is
fused when subjected to inErflred radiation.
Tory the fabric 84 passes through tensioning means 76 fabric 84 is
passed between the nip of two rolls 86 and 88 which are used to contact
fabric 84 with at least one heated roll having a temperature sufficient to
fuse together at east a portion of the fibers of the fabric in contact with
the heated roll. The fused fabric then passes to -the roll up section as
previollsly described unless the second tensioning means 102 is employed also
30 its previously lescr:ibed.
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Synthetic thermoplastic staple in general can be used in accordance
with the present invention. For example, polyolefins such as polypropylene,
polyesters such as polyethylene terephthalate, polyamides such as polycapro-
lactam, and mixtures thereof are suitable. Particularly good results have
been obtained employing polypropylene staple. When polypropylene fibers are
used to produce the non woven fabric the temperature of the fusion roll or
rolls employed is generally within a range of about 310 (154C) to about
340~F (17lC); however, temperatures within a range of about 320F (160C) to
about EYE ~165C) are more common.
The synthetic staple suitable for use in applicants invention can
be selected over a relatively wide range. Generally synthetic staple has a
length within a range of about 1-1/2 inches (3.81 cm) to about 10 inches
(25.4 cm). Good results can be obtained employing a staple length within a
range of about 2-1/2 inches (6.35 cm) to about 4 inches (10.2 cm). Staple
denier can be selected from a wide range of deniers. Normally the denier is
within a range of about 1 to about 20; however, deniers within a range of
about 1.5 to about 8 are more common.
Quartz heaters and foil-strip heaters have been used as the infrared
radiation source in accordance with the present invention; however, the
I present invention is no-t limited by the particular source used to subject the
fabric to the infrared radiation. At the present time it appears that the
Eoil-strip heaters are preferred because they provide better control of the
elusion process.
In general, fabrics with a variety of widths can be produced in
accordance with the present invention; however, the invention is particularly
applicable for the production of wide, non woven fabrics, that is, fabrics
having a width within a range of about 10~ inches (274.3 cm) to 230 inches
(5~4.2 cm).
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EXAMPLE
Five fused fabric samples were made using the apparatus of Figure 1
and 2 except that the optional tensioning means 102 and the associated infrared
fusing means 104 and 106 were not employed. The samples produced in runs 1,
2 and 3 were control samples. The fabric of run 1 was fused using infrared
radiation only and the fabrics of runs 2 and 3 were fused using roll fusion
only. The fabric of runs it and 5 were first fused with infrared radiation
and subsequently fused with a heated roll in accordance with the present
invention. All fabrics (runs 1 through 5) were produced with 4-denier polyp
propylene staple, 3-1/4 inches (8.25 cm) long and only the face side of the
fabrics was exposed to infrared radiation and/or a heated roll in order to
produce a fabric in which the fibers on the back side were substantially
unfused. All fabrics weighed 3.1 ode and were produced under essentially
the same conditions except for the fusion conditions. All fabrics were 150
winches (381 cm) wide except the fabric of run 2 which was 120 inches (304.8 cm)
Waldo. The infrared heaters employed in runs l, 4 and 5 were Leech speed foil
heaters model 2-22lt-A~ manufactured by Royal Industries, Inc., Coventry,
I In runs l, 4 and 5 the infrared heaters were stacked and positioned
traverse with respect -to the direction of movement of the fabric. The
fusion conditions for each of the runs are provided in Table I below:
able I
_ _ Run No. _ _ l _ _ _ I __ _ 3 _ 4 5
~usiorl Roil Tempera-
lure, OF Not Used 320 325 330 325
(159.8C)(162.6C)(165.4C) (162.6C)
Number of Infrared
pleaters 6 Not Used Not Used 4
Voltage applied to
Infrared Heaters 490 - - 4l~0 ~t40
The physical properties of the fabrics produced are prevailed in
Table II below.
Table II
Elongation Ultimate (2) Tear (3)
@ lo lobs, in/3 in. Strength (lobs) length (lobs) _
Run No.
l* Warp 0.2 72 24
Fill 0.4 81 28
2 Warp 0.5 62 25
Fill 0.7 74 28
3 Warp 0.4 62 26
Fill 0.3 71 30
4 Warp 0.4 68 27
Fill 0.4 87 31
Warp 0.4 68 25
Fill 0.3 92 30
(]) ASTM D 1117 74
(2) AUSTIN D 1117~74
(3) ASTM D 2263-75T
*The fabric produced in this run had a substantial portion of
the fibers on the back side of the fabric fused which reduced
the phonies or nap on the back side of the fabric and the
uniformity of the fabric had a somewhat inferior appearance
and feel as compared to the other fabrics produced in the
other runs.
As clearly Indicated in Table I the ultimate strength of the
fabric of rum 4 and 5 was higher as compared to the fabrics of rums 2 and 3.
The ultimate strength of the fabric of run I was higher than the fabrics of
rllnE~ 4 and 5 in the warp direction, but as noted above -the fabric of run 1
did not have a substantially unfused back side. The fill ultimate strength
of rural 4 and 5 is particularly noteworthy and is -the highest in all instances.
It is pointed out that the elongation values were not exactly the same in all
runs; however, except for run 2, the elongation values are considered compare
able. It it normally accepted that if elongation is lower, ultimate strength
it Lower, Lucy the ultimate strength of the fabric in run 2 Waldo be even
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lower if the elongation values were lower. The tear strength values for
the fabrics of runs 4 and S as compared to the fabrics of runs 1, 2 and 3 are
somewhat improved, although the values for ultimate strength are generally
considered more accurate for purposes of comparison.
The above runs clearly show that the fabrics of runs 4 and 5 which
were produced in accordance with the present invention provide lower elonga-
toils and/or higher ultimate strengths as compared to the prior art fabrics
produced in runs 1, 2 and 3.
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