Note: Descriptions are shown in the official language in which they were submitted.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
1
POLYPROPYLENE COMPOSITION WITH IMPROVED TENSILE
PROPERTIES, FIBERS AND NONWOVEN STRUCTURES
Field of the invention
The present invention relates generally to polypropylene compositions, spun
and drawn
fibers prepared from the polypropylene compositions, non-woven structures made
from the
fibers and methods for producing the same. Particularly it relates to high-
tenacity spun and
drawn fibers made with the polypropylene compositions. The present invention
relates to a
production process for non-woven structures comprising such high-tenacity spun
and drawn
fibers. The present invention relates to use of such fibers in articles for
construction and
agriculture, geotextiles, sanitary and medical articles, absorbent wipes,
filters, carpets,
upholstery and other textiles, e.g. in the automotive industry.
Background
Methods used in the production of the fibers and yarns as well as nonwovens
from the fibers
or yarns are known to the person skilled in the art and are for example
described in
"Synthetische Fasern", Franz Fourne, Hanser, 1995, ISBN 3-446-16058-2), pages
96-110:
typical phenomena during the spinning of polypropylene, pages 231-550:
description of all
types of spinning equipment in general. These passages are incorporated herein
by reference.
With the current state-of-the-art of PP high tenacity fibers, improved
mechanical properties
of a product can be achieved with higher base weight of the product itself.
This increases
cost and can have a negative ecological impact. The tenacity can be improved
by increasing
the draw ratio but this lowers the elongation of the fibers. Hence, when using
such over-
drawn fibers for the production of geotextile, the overall properties of the
geotextile do not
improve. Other polymers can improve mechanical performance but most such
polymers are
less inert than PP and their properties degrade faster, e.g. when in contact
with soil. Such
polymers can be more expensive.
W02014/114638 discloses high-tenacity fibers defined as having a tensile
strength of at least
45 cN/tex. It reports that polypropylenes used for spun and drawn fibers and
nonwoven
structures made with these generally have a melt flow index (MFI) in the range
of 3 to 6 g/10
min for very strong high-tenacity fibers whereas a MFI value in the range of
thousand g/10
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
2
min is selected for meltblown non-wovens.
W02014/114638 describes a method of producing high-tenacity fibers by melting
a
polypropylene composition in an extruder and extruding the molten
polypropylene through
the fine capillaries of a spinneret to obtain filaments. These filaments are
then cooled and
thus solidified. In order to increase the tensile strength, the solidified
fibers can be drawn
whereby an increase in tensile strength of the fibers occurs with increasing
draw ratio.
However, the increase in tensile strength can be accompanied by a decrease in
elongation to
break. As reported in W02014/114638 it is known to lower both the melt flow
index (MFI)
and the xylene soluble content (XS) of the polypropylene compositions to
assist in finding a
compromise between fiber tensile strength and fiber elongational properties.
For the
production of tapes and fibers the XS content is conventionally around 3.5%,
or above to
maintain a stable process.
Geotextiles can require nonwoven fabrics comprising high-tenacity spun and
drawn fibers,
e.g. in nonwoven fabrics to be needle-punched. Good elongation properties of
the fibers are
required to assure a correct impact resistance (dart) of the geotextile and to
avoid fiber breaks
during needle-punching. Hence there is a need to obtain the highest fiber
tensile strength in
combination with the highest elongation from polypropylene compositions.
W02014/114638 discloses high-tenacity drawn fibers prepared using a
polypropylene
composition comprising propylene polymer in a matrix phase and a rubber in a
dispersed
phase, preferably an ethylene propylene rubber (EPR), wherein the rubber
content of the
polypropylene composition ranges from at least 0.2 to at most 7 wt% relative
to the total
weight of the polypropylene composition. The polypropylene composition
comprises a
heterophasic propylene copolymer, also referred as an "impact copolymer" or a
"propylene
block copolymer". It is argued that good results have been obtained by the
combination of
the stiffness-to-impact balance properties of a heterophasic propylene
copolymer (in which
the rubbery phase is more homogeneously dispersed and size controlled than in
a mere blend
of propylene polymer with an elastomeric polymer or a rubber), with a
propylene polymer
having a high isotacticity to produce a propylene composition. An alternative
explanation is
that the results have been obtained by the polypropylene composition combined
with the
production process of the fibers in which the fibers are drawn in a solid
state.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
3
W02014/114638 reports that a propylene homopolymer is known for application in
geotextiles having a low MFI of 4 g/10min and low XS of 1.5 to 2.5%. However,
attempting
an improvement of fiber properties by lowering both MFI and XS still further
leads to
spinning problems such as high pressures, high temperatures, degradation of
the polymer,
damage to spinning equipment, etc. In fact the temperatures in the melt and
the shear forces
in the die can result in degradation of the polymer which reduces its
molecular weight and
hence also its mechanical properties. It is therefore not obvious how to
modify the
preparation of a homopolymer or the manufacture of high tenacity fibers made
from the
homopolymer to obtain both a high tenacity and elongation of the fibers and
ease of
manufacture with high throughputs and yields.
Summary of the invention
An aim of embodiments of the present invention can be to provide any, some or
all of:
- improved properties of a polypropylene composition comprising a
polypropylene polymer
especially a homopolymer or a polypropylene blend or a multimodal homopolymer,
- spun and drawn fibers
- non-woven structures such as needle punched non-woven structures made
with the spun
and drawn fibers, and/or
- articles for construction and agriculture, geotextiles, sanitary and medical
articles,
absorbent wipes, filters, carpets, upholstery, and other textiles, e.g. in the
automotive industry
made with such non-woven structures.
The polypropylene composition preferably has a selected window of properties
that provide
improved tensile properties while still allowing processing in conventional
fiber spinning
and drawing equipment. The polypropylene compositions of embodiments of the
present
invention comprise one or more homopolymers and no heterophasic components
such as
rubbers.
Embodiments of the present invention provide spun and drawn fibers comprising
a
polypropylene homopolymer, the spun and drawn fibers having an average MFI
measured
according to ISO 1133 for polypropylene of 1 to 5 g/10 min and a xylene
soluble content in
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
4
the range from 1 wt% to 4.5 wt% or 1.5 wt% to 4.5 wt%, the spun and drawn
fibers having:
an average elongation of at least 65% as measured by ISO 5079 with an adjusted
testing
speed of 80 mm/min, and/or an average tenacity/tensile strength of at least 56
cN/tex as
measured by ISO 5079 with an adjusted testing speed of 80 mm/min. The average
tenacity/tensile strength can be in the range 56-70 cN/tex; with 75-90%
extension to break
for example. Xylene soluble content can be in the range from 1 wt% to 2 wt%,
or 1 wt% to
3 wt%, or 1 wt% to 3.5 wt% or 1.5 wt% to 3.5 wt%, or in the range of 1 wt% to
2.5 wt% or
1.5 wt% to 2.5 wt%. The use of controlled and low values of MFI and xylene
solubility
provide high tenacity fibers that can be processed on existing spinning
equipment. The fibers
are extruded and are not slit tapes.
The polypropylene composition can consist of one or more polypropylene
homopolymers.
This can allow adjustment of processing conditions while spinning.
The fibers can be staple fibers or short cut fibers. These are useful for
making non-woven
textiles and geotextiles with good tenacity.
The spun and drawn fibers can have an average MFI measured according to ISO
1133 for
polypropylene of 2 to 4 g/10 min. This narrower range allows more control over
the extrusion
and spinning processes.
The spun and drawn fibers can have a multilobal, or preferably a trilobal
cross-section. These
cross-sections allow improved non-wovens with good elongation, tensile
strength and cover.
The spun and drawn fibers can be multicomponent fibers for example, preferably
bicomponent fibers. These fibers allow production of non-wovens with a better
performance
by producing a better bonding strength after a heat treatment.
The polypropylene composition according to embodiments of the present
invention can form
a core of the multicomponent fibers. Thus means that the core can remain
intact after a heat
treatment to bond the fibers in a non-woven such as a geotextile.
The fibers can have a titer of at least at least 1 dtex and at most 100 dtex.
This range is useful
for non-wovens such as geotextiles.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
The polypropylene composition of the spun and drawn fibers can comprise a
first and a
second polymer being a blend or a multimodal polymer composition. This allows
a balanced
set of properties to be obtained and optionally to improve processing during
extrusion and
spinning.
5
In another aspect of the present invention a nonwoven is provided comprising
the spun and
drawn fibers of embodiments of the present invention. The non-woven can be a
geotextile.
In another aspect, embodiments of the present invention provide a process for
the production
of spun and drawn fibers, comprising the steps of:
a) providing the polypropylene composition to an extruder;
b) melt-spinning said polypropylene composition from a number of openings, to
form molten
filaments; and
c) cooling the molten filaments obtained by step (b) to obtain solidified
fibers.
In this process the fibers can be drawn at a draw ratio of between 2 and 4,
e.g. 2.5 to 4.
In another aspect the present invention provides a polypropylene composition
of a
polypropylene homopolymer having an MFI measured according to ISO 1133 of 1 to
3 g/10
min and a xylene soluble content in the range 1 wt% to 4.5 wt% or 1.5 wt% to
4.5 wt%.
Xylene soluble content can be in the range from 1 wt% to 2 wt%, or 1 wt% to 3
wt%, or 1
wt% to 3.5 wt% or 1.5 wt% to 3.5 wt%, or in the range of 1 wt% to 2.5 wt% or
1.5 wt% to
2.5 wt%.
The polymer temperature in the extruder (measured at the outlet of the
extruder) and/or spin
beam, can be in the range of 255 C to 350 C, preferably in the range of 265 C
to 340 C,
more preferably in the range of 275 C to 330 C and most preferably in the
range of 285 C
to 320 C.
This polypropylene composition is suitable to make spun and drawn fibers
having an
elongation of at least 65% as measured by ISO 5079 with an adjusted testing
speed of 80
mm/min and/or an average tenacity/tensile strength of at least 56 cN/tex as
measured by ISO
5079 with an adjusted testing speed of 80 mm/min. The average tenacity/tensile
strength can
be in the range 56-70 cN/tex; with 75-90% extension to break for example.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
6
The polypropylene composition can consist of one or more polypropylene
homopolymers.
For example the polypropylene composition can comprise a first and a second
polymer, said
polypropylene composition being a blend or a multimodal polymer composition.
The polypropylene composition according to embodiments of the present
invention can be
used in the manufacture of bicomponent fibers. The bicomponent fibers can
comprise a core
and an outer layer which covers some or all of the circumference of the core,
e.g. like a
sheath, wherein the polypropylene composition is used to form the core. The
high tensile
strength and high elongation of the polymer composition of the core results in
the core of the
bonded spun and drawn fibers being preserved after bonding in a non-woven such
as in a
geotextile.
An advantage of embodiments of the present invention is that mechanical
properties of a
fiber or of a non-woven made from the fiber can be improved. A further
advantage of at least
some embodiments is that the throughput and yield of the fiber production can
be maintained
at the same time as obtaining the improved mechanical properties.
Spun and drawn fibers according to embodiments of the present invention can be
used in
woven products, or non-woven products such as dry or wet wipes, hygiene
products, filters,
carpets, upholstery, and other textiles, e.g. in the automotive industry made
with such non-
woven structures or in articles for construction and agriculture, geotextiles,
sanitary and
medical articles. Functions of such products can be filtration, reinforcement,
separation,
drainage and/or protection, for example.
Spun and drawn fibers according to any or all of the embodiments of the
present invention
do preferably not include slit tapes.
An advantage of embodiments of the present invention is the possibility of
weight reduction
of a non-woven structure, e.g. used as or in a carpet, upholstery, an
absorbent wipe or a
geotextile, while still obtaining the same properties. Further advantages of
embodiments of
the present invention can be manufacturing cost reduction of the final
product, a reduction
in environmental impact or an easier handling.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
7
Embodiments of the present invention comprise a first polymer being a
polypropylene
homopolymer having a xylene soluble content in the range from 1 wt% to 4.5 wt%
or 1.5
wt% to 4.5 wt% relative to the weight of the polypropylene homopolymer;
preferably in the
.. range from 1 wt% to 2 wt%, or 1 wt% to 3 wt%, or 1 wt% to 3.5 wt% or 1.5
wt% to 3.5
wt%, most preferably in the range from 1 wt% to 2.5 wt% or 1.5 wt% to 2.5 wt%.
The MFI
of the polypropylene homopolymer is from 1 to 3 g/10min, preferably in the
range 1.5 to 2.5
g/10min.
In an embodiment, the polypropylene composition comprises a blend of the first
polymer,
and a second polymer being a polyolefin such as polypropylene or polyethylene
in an amount
from at least 0.1 wt%, preferably in the range 0.5 to 5 wt% relative to the
total weight of the
polypropylene composition.
In a further embodiment, the polypropylene composition (with or without the
second
polymer) comprises an additive such as a polymeric processing agent (PPA)
acting as a
processing aid in an amount from at least 0.01 wt%, preferably in the range
0.01 to 0.1 wt%,
relative to the total weight of the polypropylene composition. By such
processing aids
reduced pressures and temperatures in the extruder and in the spinneret die
during spinning,
can be achieved. Both, additive and a second polymer, can be applied alone, as
such, or
together simultaneously.
The second polymer can be a polypropylene homopolymer. The second polymer can
be a
polyolefin with a second MFI (measured according to ISO 1 133 or ASTM D-1238)
higher
than the first MFI, preferably significantly higher than the first MFI. For
example, the MFI
of the second polymer can be at least 10, 20 and even 30 times higher than the
MFI of the
first polymer. The second polymer can have an MFI of less than 100 g/10 min
and can form
a mixed composition, without being heterophasic with the first polypropylene
polymer in the
melt.
The second polymer can be present in the polymer blend in at least 0.5 wt%,
preferably in
the range of 1 to 5 wt% relative to the total weight of the polymer blend, and
the second
polymer forming a monophasic composition with the first polypropylene polymer
in the
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
8
melt.
The polypropylene composition can also include an additive such as e.g. an
antioxidant, or a
UV retardant, preferably in the range of 1000 to 2500 ppm (or higher) by
weight of the
polypropylene composition.
In the melt the additive or the second polymer preferably mixes with the first
polymer, e.g.
when molten in an extruder barrel. Without being limited by theory, the
additive or second
polymer acts as a lubricant or processing aid reducing the pressure and/or
temperature in the
extruder and the spinneret which pressure and temperature are required to
extrude the
polymers with higher viscosity through the many holes of the spinneret die.
Low melt flow index means a high-molecular-weight, and hence a highly viscous
polymer.
A high melt flow index means low-molecular-weight, and hence a low viscous
polymer. Due
to the fact that polymers such as PE and PP are measured at different
temperatures, the MFI
values cannot be compared directly in extrusion where the extrusion
temperature of the PP
means that the PE is at an elevated temperature. For example, the apparent
viscosity change
between extrusion temperatures of 240 and 270 can be about 3 times for a
polyolefin. Thus,
when considering whether a polymer will act as a low viscosity extrusion
processing aid it
is necessary to take into account several factors, such as MFI, extrusion
temperatures, shear
rates as well as some aspects of the polymer such as degree of branching and
chain
entanglements.
Accordingly, in a blend of a first polypropylene homopolymer and a second
polyolefin
polymer, the first and second polymers can have melt flow indices which are
designed to
achieve the advantages of reduced extrusion pressures and/or temperatures. For
example, if
the second polymer is polyethylene, the MFI of the polyethylene can be as low
as 3 g/10min
or lower due to the reduced viscosity of PE when extruded at PP temperatures.
If the second
polymer is PP or a polymer with a melting point similar to PP then the melt
flow index of
the second polymer is preferably higher than that of the first polymer and the
ratio of the
melt flow index of the second polymer to that of the first polymer is
preferably at least 10,
and possibly in the range of 10 to 30.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
9
Further embodiments of the present invention include polymer compositions
comprising
combinations of polymers such as polypropylene and a polyolefin whereby the
compositions
preferably have a xylene soluble content in the range from 1 wt% to 4.5 wt% or
1.5 wt% to
4.5 wt% and an MFI of 1 to 3 g/10min, preferably in the range 1.5 to 2.5
g/10min. Xylene
soluble content can be in the range from 1 wt% to 2 wt%, or 1 wt% to 3 wt%, or
1 wt% to
3.5 wt% or 1.5 wt% to 3.5 wt%, or in the range of 1 wt% to 2.5 wt% or 1.5 wt%
to 2.5 wt%.
For example 80% of a PP homopolymer with an MFI of about 2 g/10 min can be
mixed with
20% of a PP homopolymer with an MFI of about 4 g/10 min. The resulting
polypropylene
composition has a melt flow index intermediate between 2 and 4, i.e. less than
3 g/10 min
when tested as PP according to ISO 1133-1:2011 or ASTM D-1238 Standard. To
this blend
processing agents or a further polymer may be added to reduce temperatures and
pressures
during extrusion.
Accordingly, embodiments of the present invention include a polypropylene
composition
comprising a polypropylene homopolymer or a blend of a first polypropylene
homopolymer
with one or more polymers such as a polyolefin, e.g. PP or PE whereby the
polypropylene
composition has a melt flow index (MFI) less than 3 g/10 min when tested as PP
according
to ISO 1133-1:2011 and a xylene soluble content in the range from 1 wt% to 4.5
wt% or 1.5
wt% to 4.5 wt%. Xylene soluble content can be in the range from 1 wt% to 2
wt%, or 1 wt%
to 3 wt%, or 1 wt% to 3.5 wt% or 1.5 wt% to 3.5 wt%, or in the range of 1 wt%
to 2.5 wt%
or 1.5 wt% to 2.5 wt%.
The first and/or second polymers can be prepared using a suitable catalyst
such as Ziegler-
Natta catalyst or a metallocene catalyst, for example.
The first polymer preferably shows one or more of the following properties:
i. a xylene soluble content in the range from 1 wt% to 4.5 wt% or 1.5 wt% to
4.5 wt%;
preferably in the range from 1 wt% to 2 wt%, or 1 wt% to 3 wt%, or 1 wt% to
3.5 wt% or
1.5 wt% to 3.5 wt%, most preferably in the range of 1 wt% to 2.5 wt% or 1.5
wt% to 2.5
wt% and
ii. a melt flow index of less than 3.0 dg/min, more preferably in the range
1.5 to 2.5 g/10 min
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
when tested as PP according to ISO 1133-1:2011 or ASTM D-1238.
High tenacity (HT) fibers can be spun and drawn using the polypropylene
composition of
the present invention. A drawn fiber according to embodiments of the present
invention
comprises filaments made from a polypropylene composition according to any of
the
5
embodiments of the present invention, the filaments having a titer, for
example of at least 1
dtex and of at most 100 dtex, preferably of at least 2 dtex and of at most 30
dtex, most
preferably of at least 3 dtex and at most 10 dtex.
The spun and drawn fibers can be used e.g. for non-woven structures in a
variety of
10
applications of which one is geotextile applications. The properties of these
high tenacity
(HT) fibers made with the polymer composition are superior to currently
available PP fibers,
these properties being for example:
= elongation (average value): at least 65%, preferably between 65-100%,
more
between 70-90%, more preferably between 75-85%, Individual fibers can vary
considerably outside these average values, e.g. between 20% and 150%. Hence
the narrower ranges are averages as determined according to the ISO norm 5079
with an adjusted testing speed of 80 mm/min.
= improved tenacity (tensile strength): at least 56 cN/tex, preferably in
the range of
56 to 70 cN/tex, more preferably in the range of 58 to 66 cN/tex determined
according to the ISO norm 5079 with an adjusted testing speed of 80 mm/min. A
range of 75-90% extension to break can be achieved for example. These are
average values for fibers, individual fibers may be well outside these ranges.
The spun and drawn fibers after extrusion have an MFI (average value from many
fibers) of
1 to 5 g/10min when tested as PP according to ISO 1133-1:2011 or ASTM D-1238.
The
small change of MFI before and after extrusion indicates a low level of
degradation which
occurs when polymer compositions of the embodiments of the present invention
are used to
produce drawn fibers.
The polymer material in such spun and drawn fibers after extrusion has a
xylene soluble
content in the range from 1 wt% to 4.5 wt% or 1.5 wt% to 4.5 wt% relative to
the weight of
the polypropylene homopolymer; preferably in the range from 1 wt% to 2 wt%, or
1 wt% to
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
11
3 wt%, or 1 wt% to 3.5 wt% or 1.5 wt% to 3.5 wt%, most preferably in the range
from 1
wt% to 2.5 wt% or 1.5 wt% to 2.5 wt%.
Fibers according to embodiments of the present invention may be solid or
hollow and/or
round or shaped and/or monocomponent or multicomponent. Shaped fibers include
multilobal fibers such as bilobal and trilobal fibers. Multicomponent fibers
include
bicomponent fibers.
Further, the invention discloses nonwoven structures comprising such fibers. A
non-woven
structure can be made with at least some of the fibers mentioned above. A
geotextile can be
produced with this new type of fibers, e.g. in the form of a needlefelt:
the tensile strength of the needlefelt is increased by at least 5% e.g. by 8%,
by 10% compared
to the current state-of-the-art. Elongation of the needlefelt is also very
satisfactory, i.e. there
is no reduction in performance.
Further, the invention discloses a geotextile produced with such fibers or
with such non-
woven structures. Further, the invention discloses a needle felt. The tensile
strength of the
needlefelt can be increased compared to current state-of-the-art by use of
fibers according to
embodiments of the present invention.
Additionally, the present invention provides a process for the production of
high-tenacity
fibers. For example, a suitable process for producing fibers in accordance
with embodiments
of the present invention comprises the steps of:
a) providing a polypropylene composition according to any of the embodiments
of the
present invention to an extruder, the extruder temperature (measured at the
outlet of the
extruder) can be in the range of 255 C to 350 C, preferably in the range of
265 C to 340 C,
more preferably in the range of 275 C to 330 C and most preferably in the
range of 285 C
to 320 C,
b) melt-spinning said polypropylene composition by pushing the polymer
composition
through a die having a number of openings, to form molten filaments;
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
12
c) cooling the molten filaments obtained by step (b) to obtain solidified
fibers, and preferably
d) drawing said solidified fibers at a temperature of at least 70 C and at
most 150 C and at a
draw ratio of at least 2, preferably 2.5 to 4 to obtain fibers with:
= elongation (average value): at least 65%, preferably between 65-100%,
more
between 70-90%, more preferably between 75-85%, Individual fibers can vary
considerably outside these average values, e.g. between 20% and 150%. Hence
the narrower ranges are averages as determined according to the ISO norm 5079
with an adjusted testing speed of 80 mm/min.
= improved tenacity (tensile strength): at least 56 cN/tex, preferably in
the range of
56 to 70 cN/tex, more preferably in the range of 58 to 66 cN/tex determined
according to the ISO norm 5079 with an adjusted testing speed of 80 mm/min.
These are average values for fibers, individual fibers may be well outside
these
ranges. The average tenacity/tensile strength can be in the range 56-70
cN/tex;
with 75-90% extension to break for example.
The spun and drawn fibers can be made into textile products or non-wovens such
as
geotextiles by conventional means.
Definitions
Throughout the present application, the terms "polypropylene" and "propylene
polymer"
may be used synonymously. The expression "% by weight" or "wt %" (weight
percent), here
and throughout the description unless otherwise defined, refers to the
relative weight of the
respective component based on the overall weight of the formulation. The
polypropylenes
used in the present invention can be produced by polymerizing propylene in the
presence of
a suitable catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst
which is well-
known to the skilled person.
The term "fibers" in for example the term "spun and drawn fibers" refers,
according to any
or all of the embodiments of the present invention as preferably not including
slit tapes. The
fibers of any of the embodiments of the present invention can be staple fibers
of several
centimetres length, e.g. 20 to 120 mm length or up to 300 mm length or may
comprise short-
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
13
cut fibers of 2 to 25 mm in length.
A "nonwoven structure" which can be used with the present invention may
include fibers
of any of the embodiments of the present invention, e.g. as staple fibers of
several centimetres
length, e.g. 20 to 120 mm length or up to 300 mm length. A nonwoven structure
can also be
made comprising short-cut fibers of 2 to 25 mm in length, e.g. alone or in a
blend.
The term "needlepunched" means a nonwoven structure which is consolidated by
passing
it through one or more needleboards carrying several thousands of needles that
penetrate the
nonwovens repeatedly, forming a mechanically entangled structure.
"Geotextiles" and "landscape textiles" are used, for example, to cover an area
of ground.
Geotextiles, as used in this application relate to fabrics made from non-woven
structures.
They have many applications in the field of civil engineering such as in
roads, airfields,
railroads, embankments, retaining structures, reservoirs, canals, dams, bank
protection, in
the field of coastal engineering to control erosion of shorelines, as well as
in the fields of
agriculture and landscape preservation, for purposes including moisture
retention, water
conservation, weed or sward suppression, soil warmth retention, and for light
reflection. A
geotextile or landscape textile according to embodiments of the present
invention is generally
supplied in a roll and is simply unrolled to cover an area of ground.
Test methods
Melt Index (MI), Melt Flow Index (MFI), or Melt Flow Rate (MFR) refers to the
grams per
10 minutes pushed out of a die of prescribed dimensions according to ISO 1133-
1:2011 or
ASTM D-1238 Standard under the action of a specified load. For PP the load is
2.16 kg and
the die dimensions are D = 2.095 mm and L = 8 mm. The experiment is carried
out at 230 C.
(For the PE, the same load and die dimensions are used, but the experiment is
carried out at
190 C).
An example of a suitable method to determine the Xylene Solubles (%XS) is
(preferably to
be performed in double):
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
14
- In an Erlenmeyer, weigh 4 +/- 0.1 g of the polymer
- Add 200 ml of inhibited and degassed Xylene
- Heat under stiffing to reflux until complete dissolution (+/- 45 min)
under nitrogen
flow
- Allow cooling for 15-20 minutes
- Place the Erlenmeyer in a thermostatic bath at 25 +/- 0.1 C for 45
minutes and allow
cooling
- Filter the content of the Erlenmeyer using Whatman n 2 V filter paper.
- Pipette 100 ml of the filtrate on a weighed Al tray
- Evaporate the solvent on a heating plate under nitrogen (at around 130 C)
- After complete evaporation, place the tray in the vacuum oven at 105 C
for 30 minutes
- Allow cooling for 1 hour and weigh.
The percentage of xylene solubles ("XS") is calculated according to :
XS% (in weight%) = 100 x [2 x ((mass of the tray and residues) ¨ (mass of the
empty tray))
- (mass of the residue if any of a blank xylene sample)] / (mass of the sample
polypropylene
polymer) with all weights being in the same units, such as for example in
grams.
Detailed description of the invention
Polymer blend or bimodal polymer
The spun and drawn fiber of some or all embodiments of the present invention
is produced
from a polymer composition that can comprise a homopolymer, a polymer blend or
a
polymer with multimodal fractions. The polypropylenes used in the present
invention are
produced by polymerizing propylene in the presence of a suitable catalyst such
as a Ziegler-
Natta catalyst or a metallocene catalyst which methods are well-known to the
skilled person.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
Polypropylene polymers are preferably produced by polymerization in propylene
at
temperatures in the range from 20 C to 100 C. Preferably, temperatures are in
the range from
60 C to 80 C. The pressure can be atmospheric or higher. Preferably, the
pressure is between
and 50 bar.
5
Preferably, the polymer blend according to some embodiments of the invention
comprises a
first polypropylene homopolymer with an MFI less than 3 and preferably in the
range 1 to
2.5 g/10min according to ISO 1133-1:2011 or ASTM-1238, condition L, using a
weight of
2.16 kg and a temperature of 230 C and a second polyolefin polymer. If the
second polymer
10 has a lower melt temperature than PP, as is the case for polyethylene
then the MFI of this
second polymer may be similar to PP, e.g. less than 3 g/10 min tested
according to ISO 1133-
1:2011 or ASTM-1238 for conditions for PE. This is because the MFI is measured
at two
different temperatures with the temperature for PE being lower than for the PP
composition
(190 C for PE, 230 C for PP). The PE is present in the extruder at melt
temperatures for PP
15 which means the viscosity of the PE is reduced. If the second polymer is
PP, then it is
preferred it has a higher melt flow index, wherein the ratio of the melt flow
index of the
second polymer and the melt flow index of the first polymer is preferably in
the range of
more than 10 times, more than 20, more than 30, 40 or 50 times and can be less
than 100
times. The MFI of the second polymer if it is PP can be at least 20 g/10min,
at least 30
20 g/10min, at least 40 g/10min, at least 50 g/10min, at least 60 g/10min,
at least 70 g/10min
and can be less than 100 g/10min. The polypropylene composition can also
include an
antioxidant. The antioxidant can be in the range 1000 to 2500 ppm weight or
higher of the
first polymer.
25 Processing aid preferably does not affect the elongation/tensile
properties of the spun and
drawn fiber to any significant degree.
The first polymer is a polypropylene homopolymer. The optional second polymer
is
preferably miscible with the first polymer when molten, e.g. in the extruder
before spinning.
Hence it is preferred if the second polymer is a polyolefin, e.g.
polypropylene or
polyethylene. The first polymer, i.e. the polypropylene homopolymer and the
second
polymer can be mixed together in pelletized, fluff or powder form prior to
being introduced
into the extruder. Alternatively the polymers may be introduced separately
into the extruder
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
16
at one or more positions to achieve thorough mixing of the polymers within the
extruder
which feeds a spinneret. Alternatively the polymers may be introduced into
different
extruders. Additives can be melted in a separate (e.g. smaller) side extruder
and afterwards
mixed in the main stream in a mixing zone at the end of the main extruder or
by static mixers
after the extruder. The temperature in the extruder (measured at the outlet of
the extruder)
can be in the range of 255 C to 350 C, preferably in the range of 265 C to 340
C, more
preferably in the range of 275 C to 330 C and most preferably in the range of
285 C to
320 C.
The low MFI of the first polymer means that the average molecular weight of
the first
polymer is preferably increased. This higher molecular weight can be achieved
by known
methods such as by altering the amount of hydrogen injected into the
polymerisation reactor.
Peroxide can be used to lower the molecular weight of a material with a too
high molecular
weight. This can be used to set a specific MFI by starting with PP with an
even lower MFI
than finally required and then using the peroxide to increase the MFI, e.g. by
reactive
extrusion.
In an embodiment of the invention, instead of a blend of a first and a second
polymer, the
first polymer can be bimodal or multimodal and can comprise at least two
polypropylene
homopolymer fractions of different molecular weight. The bimodal or multimodal
polymer
will have a melt flow index of less than 3 g/10min, preferably in the range 1
to 2.5 g/10min
tested according to ISO 1133-1:2011 or ASTM-1238, condition L, using a weight
of 2.16 kg
and a temperature of 230 C. Such a bimodal polypropylene homopolymer is
preferably
produced in a polymerization unit having two reactors in series. In such a
sequential
arrangement of polymerization reactors, the polypropylene homopolymer
withdrawn from
one reactor is transferred to the one following in the series, where the
polymerization is
continued. To produce polypropylene homopolymer fractions of different index,
the
polymerization conditions in the respective polymerization reactors need to be
different, for
example in that the hydrogen or peroxide concentration in the polymerization
reactors
differs.
Independently of whether the blend or the multimodal distribution is selected,
the first
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
17
polymer and the second polymer are preferably in a monophasic state when
molten.
Generally, the higher molecular weight, the higher is the tensile strength and
modulus of the
spun and drawn fibers. However, lowering the MFI means that the material
becomes more
viscous and this will increase the pressure in the extruder and the die of the
spinneret. Partial
compensation for these negative effects on extrusion and melt-spinning of
polymer material
can be achieved with an increase in temperature, e.g. to lower the high
viscosity at normal
operation conditions. To minimize degradation caused by this higher
temperature, a higher
amount of anti-oxidant is preferred in the polymer composition.
The first polymer preferably has the following properties in addition to the
MFI and
antioxidant mentioned above. The percent atactic material is less than 5% and
preferably
between 1.5 and 2wt% e.g. between 1.6 and 1.8 wt% of the total weight of the
first polymer
as measured by xylene soluble content.
Gel count is an indication for the homogeneity of the product and is
preferably negligible.
The chemical structure of the polymer can be defined as atactic, isotactic or
syndiotactic.
These refer to an idealised sequence of the stereographic arrangement of the
methyl groups
in the polymer. This 3-dimensional orientation and sequence will determine how
the polymer
molecule will arrange by folding-up, crystallizing, etc. Atactic means that
the methyl groups
will be randomly arranged, so will not fold up symmetrically, and appear like
a sticky product
(glue). Isotactic means that all methyl groups will be on the same side of the
polymer chain,
so that the molecule can fold-up in a symmetric way, and in crystals. With
syndiotactic
products the methyl groups are each time on alternating sides. In any actual
polymer
'artefacts' in the catalyst polymerization can take place.
Laboratory analysis can be used to extract or to spectrometrically determine
the amounts of
these different polymer arrangements. In case of extraction, heptane solubles
or insolubles
or Xylene solubles or insolubles can give an idea of the atactic content. Low
molecular
weight polymer (if present) can also be extracted and counted as atactic
material. There is
also a limit on the efficiency of extraction, which makes that not all atactic
polymer will be
measured. The same uncertainty of measurements is the case of spectrometrical
analysis
(NMR / near IR / X-ray diffraction).
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
18
Fiber production
An apparatus that can be used for spinning melt-spun fibers according to
embodiments of
the present invention can include a spin beam. A spin beam is known from US
patent
application US2004/0124551 which is incorporated herein by reference. A
polymer melt
from an extruder is fed to the spin beam and is distributed within the spin
beam to a plurality
of spinning cans mounted on the spin beam. The extruder and the spin beam are
provided
with heaters. The temperature in the extruder (measured at the outlet of the
extruder) and/or
spin beam, can be in the range of 255 C to 350 C, preferably in the range of
265 C to 340 C,
more preferably in the range of 275 C to 330 C and most preferably in the
range of 285 C
to 320 C.
Spun and drawn fibers according to any or all of the embodiments of the
present invention
preferably do not include slit tapes.
A process according to an embodiment of the present invention includes:
1) Dosing of amounts of first and optionally second or further polymers
according to
embodiments of the present invention which polymers also comprise an anti-
oxidant with
optionally other nipmentc and/or other achlitivec
2) Extrusion melting, mixing, and pressure increase with extrusion of polymer
material in
the form of filaments under pressure through a die of a spinneret
3) Quenching the filaments from molten material to solid filaments
4) During steps 2) and 3) the filaments can be drawn a first time ('melt
drawing')
5) Spinfinish application: this improves antistatic property and reduces the
abrasion. This
result in stable processing during fiber production and nonwoven production.
Extra
spinfinish is often added in later stages of the process (e.g. after
texturation of cutting ¨ see
below)
6) Stretching by drawing the solidified filaments to achieve a good tensile
strength by
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
19
increasing the orientation. The draw ratio of this step is used to
characterize how much the
filaments are drawn. Conventionally fibers are drawn in one or two steps; some
manufacturers also provide equipment which allows fibers to be drawn in many
small steps.
It is assumed that many small steps can be described as a single final drawing
ratio. During
this process, an oven is used to heat the fibers. This reduces the required
drawing force and
can improve the final properties
7) Stabilising: A stabilizing step can be added to the process to reduce the
internal stresses
within the fibers and thus reduce shrinkage.
8) Texturation: Filaments are crimped/textured to increase the bulk and the
cohesion of the
fibers. This process can be improved by treating the fibers with steam prior
to the texturation
step.
9) Optional secondary spin finish operation: after drawing of the fibers,
optional application
of a second spin finish, optional crimping or texturizing can be performed.
Steam processing
better texturation is preferred because some spin finish can be removed during
texturation.
10) Optionally cutting the fibers to a length such as 20mm to 300 mm to form
staple fibers
or 2-24 mm for short cut fibers.
Alternatively, a two-step process can be used, wherein material is collected
between the
quenching and stretching steps. In a two-step process steps 1 to 3 aren't
coupled to the rest
of the process. After quenching in step 3), filaments are collected in bins or
on bobbins. The
advantage of this process is that the first steps can be performed at much
higher spinning
speeds. Main drawback of this process is the extra workload.
In addition some extra steps may be included in both the one step and two-step
process.
These additional steps can be, for example, relaxation or crimping.
It is preferred that the first polypropylene polymer used for the production
of high tenacity
fibers has a low XS value and also a low MFI. This leads to stronger fibers
but makes the
spinning process more difficult, e.g. filaments tend to fracture more easily
during spinning
when %XS is low and extrusion temperatures and pressures are higher for low
MFI.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
Embodiments of the present invention avoid these problems while maintaining
high
tenacities and elongations. Whereas a conventional polypropylene homopolymer
having an
MFI of 4 g/10min and low XS of 1.5 to 2.5% can be used for geotextile fibers,
attempting an
improvement of fiber properties by lowering still further one or both of MFI
and XS leads to
5 spinning problems such as high pressures, high temperatures, degradation
of the polymer,
damage to spinning equipment, etc.
For example, if the same spinning settings are used for spinning PP with MFI
of 2 g/10min
as the spinning settings which are used for commercial PP fiber grades, i.e.
with an MFI in
the range 4 ¨ 25 g/10min, pressures increase dramatically potentially causing
damage to the
10 equipment (extruder and spinneret) or an emergency stop of the machine
within a short time,
e.g. a matter of minutes or even perhaps degradation of the polymer.
When using a first polypropylene according to embodiments of the present
invention such
as a polypropylene homopolymer having a low MFI, e.g. of less than 3 such as
in the range
1 to 2.5 g/10min and a low XS, e.g. in the range 1 wt% to 2.5 wt% or 1.5 to
2.5%, or 1 wt%
15 to 2 wt%, or 1 wt% to 3 wt%, several precautions should preferably be
taken:
a) Increase temperature of extruder and spin beam, e.g. raise it by 10 C, 20
C, 30 C or 40 C
or even more, such as raising the temperature e.g. from 245 to 275 C while
preferably lower
than 350 C, lower than 320 C, preferably lower than 295 C, preferably below
290 C, for
example in the range 275 C to 330 C or 285 C to 320 C.
20 b) Lower output from spin pump speed, e.g. reduce the speed by 10 % or
20%.
c) Include a second polymer in a blend with the first polymer or as a
multimodal or bimodal
polymer, the second polymer acting as a processing aid. If the second polymer
is
polypropylene the second polymer preferably has a higher MFI than the first
polymer, e.g.
by 10 times, 20 times or 25 times such as an MFI of 50 g/10min. The MFI range
for the
second polymer can be at least 20 g/10min, at least 30 g/10min, at least 40
g/10min, at least
50 g/10min, at least 60 g/10min, at least 70 g/10min and can be less than 100
g/lOmin.If the
second polymer is polyethylene the MFI can be the same as for the first
polymer.
d) Internal and external lubricants, are known and can be used. Internal
lubricants often
exhibit a certain external lubrication.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
21
Internal lubricants are believed to reduce friction occurring between the
molecular chains of
a polymer thus lowering the melt viscosity. They can be polar materials.
External lubricants mainly reduce wall adhesion between the polymer and metal
surfaces.
Most of them are non-polar substances, such as paraffins or polyethylene. The
external
lubrication is influenced by the length of the hydrocarbon chain, the
branching or the
functional groups. However, these known lubricants have a low molecular weight
and have
an effect on the MFI of the extruded polymer composition.
Contrary to these known lubricants, a blend or multimodal composition is
provided of a first
polymer according to embodiments of the present invention with a low MFI. The
second
polymer can be present in an amount less than 5%, e.g. 1 to 5%, 2 to 3%, or
2.5% of the
polymer composition. If the second polymer is a polypropylene this polymer
preferably has
an MFI higher than the first polymer, e.g. by 10 times, 20 times or 25 times
such as an MFI
of 50 g/10min. The MFI range for the second polymer can be at least 20
g/10min, at least 30
g/10min, at least 40 g/10min, at least 50 g/10min, at least 60 g/10min, at
least 70 g/10min
and can be less than 100 g/10min. For a multimodal composition a combination
of polymers
such as a combination of polypropylene with an MFI of 2 (80% by weight) and a
polypropylene with an MFI of 4 (20% by weigh) results in a polymer with an MFI
less than
3, e.g. between 1 and 2.5. Fibers in accordance with embodiments of the
present invention
can be produced with 100% of the first polymer (no second polymer) as well but
this may
reduce spinning speed
Other additives which can be blended with the first polymer or with the first
and second
polymers to reduce pressure build-up include a polymer processing agent.
Further additives can be, by way of example, antioxidants, UV retardants,
light stabilizers,
acid scavengers, flame retardants, lubricants, antistatic additives,
nucleating/clarifying
agents, colorants. An overview of such additives may be found in Plastics
Additives
Handbook, ed. H. Zweifel, 5th edition, 2001, Hanser Publishers. Antioxidants
can be selected
from the group consisting of or comprising phosphites, hindered phenols,
hindered amine
stabilizers and hydroxylamines. Alternatively, phenol-free antioxidant
additives are suitable
as well, such as for example those based on hindered amine stabilizers,
phosphites,
hydroxylamines or any combination of these.
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
22
Fiber properties - shape
Fibers according to embodiments may be solid round, hollow round, solid shaped
or hollow
shaped such as multilobal fibers, bilobal or trilobal fibers, bicomponent
fibers of any of these
e.g. bicomponent solid round, bicomponent hollow round, bicomponent solid
shaped or
bicomponent hollow shaped such as bicomponent multilobal fibers, bicomponent
bilobal or
bicomponent trilobal fibers. Spun and drawn fibers according to any or all of
the
embodiments of the present invention preferably do not include slit tapes.
Fibers for non-woven structures can be made with polymers according to
embodiments of
the present invention catalyzed by a metallocene catalyst. Such fibers can be
spun into a bi-
component fiber by methods as described in Belgian patent application BE
2016/5213
entitled "Non-woven structure with fibers catalyzed by a metallocene catalyst"
which is
incorporated herein in its entirety by reference. Bonded and entangled non-
woven structures
for use, for example, in hygiene and health care, such as in disposable or
single use products
for use, for example in hospitals, schools, and domestically, in diapers or
wipes, but also in
carpets can be made with such non-woven structures. Mechanical properties of
geotextile or
upholstery nonwoven structures can be improved by adding such metallocene bi-
component
fibers for better bonding. The amount of metallocene bi-component fibers used
in a non-
woven can range from 5% to 100% of the fibers used to make the non-woven.
It is preferred if the core of such bi-component fibers is made from the first
polypropylene
polymer with a low MFI or a blend or multimodal composition of the first and
second
polymers according to embodiments of the present invention, as this improves
the tensile
properties of the non-woven such as the needlefelt made with these fibers. On
the other hand,
making the bi-component fibers from a polypropylene according to embodiments
of the
present invention with this low MFI material being the cladding or sheath
material of bi-
component fibers is less preferred due to the reduction in tensile properties
when the
polypropylene sheath melts to produce bonding to adjacent fibers.
A further embodiment of the present invention comprises a bicomponent fiber
with a core
made from the first polypropylene polymer with a low MFI or a blend or
multimodal
composition of the first and second polymers according to embodiments of the
present
invention. The outer polymer material of the bi-component fiber is preferably
made of a
polypropylene polymer produced using a metallocene catalyst which has a lower
melting
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
23
temperature than the core material. Such bi-component fibers can be used in a
variety of
applications such as in the production of non-wovens for use in geotextiles or
upholstery.
Non-wovens made with such bi-component fibers can have advantages of extra
stiffness and
better form stability. An embodiment of the present invention provides in one
aspect a
bonded and entangled non-woven structure made of at least 50% short cut or
staple fibers by
weight of the bonded and entangled non-woven structure, and at least a partial
bonding of
the fibers of the non-woven structure, the at least partial bonding comprising
thermally
activated bonds between a first polypropylene composition with an MFI less
than 3 g/10 min
and a second outer material produced with at least one metallocene catalyst
and having a
melting point at least 10 C lower than the melting point of the first
polypropylene
composition, the weight of the second material in the non-woven structure
being at least 3%
of the weight of the nonwoven structure.
Fibers according to an embodiment of the present invention can be made from a
polypropylene polymer with an outer trilobal shape, either as hollow or solid
fibers.
The shape of the fibers influences the mechanical properties especially the
permeability for
air and water. Such trilobal fibers can improve geotextiles or filters. For
example, trilobal
shape increases the contact surface which can increase bond strengths or
filtering
characteristics as well as better contact between constructional materials
such as concrete
and fibers or non-woven structures made according to embodiments of the
present invention
The trilobal shape can also improve the coverage of the carpet or upholstery,
e.g. a better
coverage with a conventional base weight or a desired coverage with a lower
weight.
Fibers according to an embodiment of the present invention can be bi-component
fibers
having a sheath and a core, wherein the core comprises the polypropylene
composition
according to the present invention, and wherein the sheath may comprise a
polyolefin such
as PE or PP, preferably PP, catalysed by a metallocene catalyst and the
bicomponent fiber
preferably having an outer trilobal shape. This combines several advantages
and can find a
use in upholstery or geotextile.
Fiber properties - mechanical
Measured properties of fibers according to embodiments of the present
invention show an
improvement compared to fibers produced on the same line with Total 4069
polypropylene
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
24
(MFI 4 g/10min) or with Polychim HL1OXF polypropylene (having MFI 3.5
g/10min):
Fibers according to embodiments of the present invention (e.g. for 4.4 dtex)
showed a higher
tenacity e.g. above 56 or 58 cN/tex such as 62 cN/tex, as well as maintaining
the elongation.
Fibers according to embodiments of the present invention achieve:
= elongation (average value): at least 65%, preferably between 65-100%, more
between 70-90%, more preferably between 75-85%, Individual fibers can vary
considerably outside these average values, e.g. between 20% and 150%. Hence
the narrower ranges are averages as determined according to the ISO norm 5079
with an adjusted testing speed of 80 mm/min.
= Improved tenacity (tensile strength): at least 56 cN/tex, preferably in the
range of
56 to 70 cN/tex, more preferably in the range of 58 to 66 cN/tex determined
according to the ISO norm 5079 with an adjusted testing speed of 80 mm/min.
These are average values for fibers, individual fibers may be well outside
these
ranges. The average tenacity/tensile strength can be in the range 56-70
cN/tex;
with 75-90% extension to break for example.
Production of needlepunched nonwoven structures
A nonwoven structure according to embodiments of the present invention can
include any of
the fiber embodiments of the present invention, e.g. fibers made from a first
polymer being
a polypropylene homopolymer with an MFI between 1 and 2.5 g/10min, with a
xylene
soluble content in the range from 1 wt% to 4.5 wt%, or 1.5 wt% to 4.5 wt%
relative to the
weight of the polypropylene homopolymer; preferably in the range from 1 wt% to
2 wt%, or
1 wt% to 3 wt%, 1 wt% to 3.5 wt% or 1.5 wt% to 3.5 wt%, most preferably in the
range
from 1 wt% to 2.5 wt% or 1.5 wt% to 2.5 wt%, relative to the weight of the
polypropylene
homopolymer and the shape of the fibers can be any of solid round, hollow
round, multilobal
solid or hollow such as trilobal solid or hollow, bi-component solid round or
hollow round,
or multilobal bicomponent either hollow or solid such as bicomponent trilobal
either solid
or hollow, with any of the fibers being optionally crimped. Any of such fibers
can have an
elongation (e.g. for 4.4 dtex), above 65% and (e.g. for 4.4 dtex) tenacity
above 56 cN/tex, as
well as maintaining the higher elongation. The polymer composition used to
make any of the
fibers can be a blend or a multimodal composition. In a blend the first
polymer according to
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
embodiments of the present invention has a low MFI less than 3 g/10 min and
less than 5%,
e.g. 1 to 5%, 2 to 3%, or 2.5% of a second polyolefin polymer such as a PE
polymer with an
MFI similar to that of the first polymer or a polypropylene polymer with an
MFI higher than
the first polymer such as 10 times, 20 times or 25 times higher. The MFI range
for the second
5 PP polymer can be at least 20 g/10min, at least 30 g/10min, at least 40
g/10min, at least 50
g/10min, at least 60 g/10min, at least 70 g/10min and can be less than 100
g/10min.
The nonwoven structure can be entangled e.g. by needle punching or hydro-
entanglement.
The fibers can be spread in a uniform web by an air-laid process, e.g. for
making nonwoven
10 structures for use in mats, gauzes, scrims; sheets etc. The nonwoven
structure can be made
by needle punching. The fibers can be put into bales, placed on a conveyor
belt and
dispersed, e.g. spread in a uniform web by a wetlaid, airlaid, or
carding/crosslapping process.
Non-woven structures according to embodiments of the present invention can be
made by
calender-thermal bonding technology. For example carded veils including
bicomponent
15 fibers according to any of the embodiments of the present invention can
be subjected to the
action of pressure and temperature of a calender. Alternatively, non-woven
structures
according to embodiments of the present invention can be made by means of air-
through
bonding technology. In this process carded veils including bi-component fibers
according to
any of the embodiments of the present invention are subjected to the action of
hot-air.
20 A nonwoven structure according to embodiments of the present invention
can have a basic
weight between 10 (or 12) gsm and 170 gsm for some applications such as for
carpets,
gauzes, fleece, hygiene products, wet or dry wipes, geotextiles or between 100
and 2000 gsm
for others such as carpets, upholstery or geotextiles.
Needlepunched non-woven structures can be prepared by any of the following
methods.
25 Entangled nonwoven structures according to embodiments of the present
invention can be
needle punched and can be produced using an industrial scale needle punch
production line.
For example, fibers such as staple or short cut fibers according to any of the
embodiments of
the present invention are mixed and formed into a bat or mat using carding and
cross-lapping.
The mat can be pre-needled using plain barbed needles. Non-woven structures
according to
some embodiments of the present invention can be produced by first producing a
needle
punched non-woven structure as defined above and then subjecting the non-woven
structure
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
26
to a bonding operation, e.g. by thermal processing.
Comparative tests
Needlepunched non-woven structures were produced:
1. With PP fibers made of Polychim HL1OXF polypropylene having an MFI 3.5
g/10min for comparison purposes
2. With PP fibers produced according to embodiments of the present invention
having an MFI of 2 g/10min.
Other than the PP-type which was used, all other properties were kept
identical for all fibers:
titer was 4.4 dtex, cutting length was 90 mm, the fibers were not colored, and
the same
texturation and spin finish were used.
Geotextile needlefelt with a weight of 120 g/m2 was produced with each of the
fiber types,
test 1 being the comparative values and test 2 that of the present invention.
Carding and needling settings were kept identical for all the tests.
The properties of the needlefelt geotextile were measured by means of tensile
testing:
1. According to ISO 10319
(Speed of the clamps was changed from the norm values to increase testing
speed, i.e.
50 mm/min)
2. There were a minimum 2 repeats for each type of needlefelt
3. Each repeat = 6 samples MD (machine direction) + 6 samples CD (cross-
direction)
4. Samples were taken over the entire width of the geotextile + measured in
the correct
order (i.e. samples 1 & 6 are on the outside of the felt).
The results are shown in table 1 which indicates the improved performance of
the non-woven
structures according to the present invention.
Applications of fibers and non-woven structures according to embodiments of
the
present invention:
CA 03056171 2019-09-11
WO 2018/167304 PCT/EP2018/056746
27
Fibers and non-woven structures in accordance with embodiments of the present
invention
can be used in upholsters, for which mechanical properties are often the most
stringent
requirements. The stronger fibers in accordance with embodiments of the
present invention
result in a lower base weight required for such a textile.
Fibers or non-woven structures in accordance with embodiments of the present
invention can
be used in reinforced constructional products such as in concrete
reinforcement including the
fibers for which a high strength of the fibers is important.
Fibers and non-woven structures in accordance with embodiments of the present
invention
can be used for composite applications, e.g. in combination with other fiber
types such as
glass fibers, carbon fibers or natural fibers (wood, flax, hemp).
Table 1
Average Elongation Average Tensile strength
Test # CD/MD
Test 1 CD 62,93 8,47
MD 61,92 5,96
Total 62,42 7,22
Test 2 CD 74,57 8,95
MD 63,06 6,74
Total 68,29 7,84
