CN110582595A

CN110582595A - polypropylene composition with improved tensile properties, fibers and nonwoven structures

Info

Publication number: CN110582595A
Application number: CN201880025104.4A
Authority: CN
Inventors: I·博格炯; J·也森波特; T·弗洛曼; B·高瑟; J-L·万德莫氏
Original assignee: Bo You International Group Ltd By Share Ltd
Current assignee: Bo You International Group Ltd By Share Ltd; Beaulieu International Group NV
Priority date: 2017-03-17
Filing date: 2018-03-16
Publication date: 2019-12-17
Also published as: EP3596259A1; CA3056171A1; US20200095708A1; WO2018167304A1; KR20190124789A

Abstract

A polypropylene composition is described having an MFI of 1 to 3 g/10 min measured according to ISO1133 for polypropylene and a xylene solubles content ranging from 1 wt% to 4.5 wt%, alternatively from 1.5 wt% to 4.5 wt%, the composition can be used for producing spun drawn fibers having an average MFI of 1 to 5 g/10 min measured according to ISO1133 for polypropylene, and a xylene soluble content in the range of 1 to 4.5 wt.%, or 1.5 to 4.5 wt.%, the spun drawn fiber has an average elongation of at least 65% as measured according to ISO 5079 at an 80 mm/min adjusted test rate, and/or an average toughness/tensile strength of at least 56cN/tex as measured according to ISO 5079 at an 80 mm/min adjusted test rate.

Description

polypropylene composition with improved tensile properties, fibers and nonwoven structures

Technical Field

The present invention relates generally to polypropylene compositions, spun drawn fibers prepared from the polypropylene compositions, nonwoven structures made from the fibers, and methods of making the same. In particular to high tenacity spun drawn fibers made from the polypropylene composition. The present invention relates to a process for producing a nonwoven structure comprising such high tenacity spun drawn fibers. The present invention relates to the use of such fibers in construction and agricultural applications, geotextiles, hygiene and medical applications, absorbent wipes, filters, carpets, upholstery and other textiles, for example, in the automotive industry.

Background

Methods for producing fibers and yarns and for producing nonwovens from such fibers or such yarns are known to the person skilled in the art and are described, for example, in "synthetic fibers" (synthetic fibers) (Franz Fourn, Hanser, 1995, ISBN 3-446-: typical phenomena in polypropylene spinning process, page 231-: all spinning equipment types are generally described. These paragraphs are incorporated herein by reference.

The current state-of-the-art high tenacity PP fibers are used to achieve improvements in the mechanical properties of the product at its own higher basis weight. This increases costs and may negatively impact ecology. Tenacity can be improved by increasing the draw ratio, but this reduces the elongation of the fiber. Therefore, when a geotextile is produced using such an over-stretched fiber, the overall performance of the geotextile is not improved. Other polymers may improve mechanical properties, but most of these polymers are more active than PP, for example when in contact with soil, and their properties deteriorate faster. These polymers may be more expensive.

WO2014/114638 discloses high tenacity fibers, which are defined as having a tensile strength of at least 45 cN/tex. It is reported that polypropylene used for spinning drawn fibers and nonwoven structures made from these fibers typically have a Melt Flow Index (MFI) of 3 to 6 grams/10 minutes, are very strong, high tenacity fibers, but MFI values in the kilogram/10 minute range are selected for melt blown nonwovens.

WO2014/114638 describes a process for producing high tenacity fibers by melting a polypropylene composition in an extruder and extruding the molten polypropylene through capillaries of a spinneret to obtain filaments. The filaments are then cooled and solidified. To increase the tensile strength, the cured fiber may be drawn, thereby increasing the tensile strength of the fiber as the draw ratio increases. However, this increase in tensile strength may be accompanied by a decrease in elongation at break. As reported in WO2014/114638, it is known that reducing the Melt Flow Index (MFI) and the xylene solubles content (XS) of a polypropylene composition helps to find a balance between fiber tensile strength and fiber elongation properties. For ribbon and fiber production, the XS content is typically about 3.5% or higher to maintain stable processing.

Geotextiles may require nonwoven fabrics comprising high tenacity spun drawn fibers, for example, needle punched into a nonwoven fabric to form the geotextile. Good fiber elongation properties are required to ensure proper impact resistance (dart) of the geotextile and to avoid fiber breakage during needling. Therefore, there is a need to obtain the highest combination of fiber tensile strength and highest elongation from polypropylene compositions.

WO2014/114638 discloses high tenacity drawn fibers prepared using a polypropylene composition comprising a propylene polymer in a matrix phase and a rubber, preferably an Ethylene Propylene Rubber (EPR), in a dispersed phase, wherein the content of said rubber of the polypropylene composition is at least 0.2% by weight and at most 7% by weight relative to the total weight of the polypropylene composition. The polypropylene composition comprises a heterophasic propylene copolymer, also referred to as "impact copolymer" or "propylene block copolymer". It is believed that good results have been obtained by combining the stiffness-impact balance properties of heterophasic propylene copolymers, wherein the rubber phase has a more uniform dispersion and size control than with blends of propylene polymers alone with elastomeric polymers or rubbers, with propylene polymers having a high isotacticity. Another explanation is that the result is obtained by combining a polypropylene composition with the production process of the fiber, wherein the fiber is solid state drawn.

WO2014/114638 reports that propylene homopolymers are well known for use on geotextiles having a low MFI of 4 grams/10 minutes and a low XS of 1.5 to 2.5%. Attempts to improve fiber properties by reducing both MFI and XS still further cause spinning problems such as high pressure, high temperature, polymer degradation, damage to spinning equipment, etc. In fact, both the melt temperature and the shear forces in the mold cause the polymer to degrade, lowering its molecular weight and thus its mechanical properties. It is therefore not obvious how to modify the preparation of homopolymers or how to prepare high tenacity fibers from the homopolymers to achieve high tenacity and high elongation of the fibers and to easily produce them at high throughput and yield.

Disclosure of Invention

it is an object of embodiments of the invention to provide any, some or all of the following:

-an improved property of a polypropylene composition comprising a polypropylene polymer, in particular comprising a homopolymer, or a polypropylene blend, or a multimodal homopolymer;

-spinning the drawn fibres;

Nonwoven structures, for example needle-punched nonwoven structures made using the spun drawn fibers, and/or

building and agricultural articles, geotextiles, hygiene and medical articles, absorbent wipes, filters, carpets, upholstery and other textiles, for example, automotive industry articles made using such nonwoven structures.

the polypropylene composition preferably has a selected range of properties, i.e. provides improved drawing properties, while still allowing processing in conventional fiber spin draw equipment. The polypropylene composition of the present embodiment comprises one or more homopolymers, but no heterophasic component (e.g. rubber).

Embodiments of the present invention provide spun drawn fibers comprising a polypropylene homopolymer having an average MFI of 1 to 5 g/10 min as measured according to ISO1133 for polypropylene and a xylene solubles content in the range of 1 wt% to 4.5 wt%, or 1.5 wt% to 4.5 wt%, the spun drawn fibers having the following properties: an average elongation of at least 65% as measured according to ISO 5079 at an 80 mm/min adjusted test rate and/or an average toughness/tensile strength of at least 56cN/tex as measured according to ISO 5079 at an 80 mm/min adjusted test rate. The average toughness/tensile strength may be, for example, in the range of 56 to 70cN/tex, and have an elongation at break of 75 to 90%. The xylene solubles content may be in the range of 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 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 can provide high tenacity fibers that can be processed on existing spinning equipment. The fibers are extruded and are not slit ribbons.

The polypropylene composition may be composed of one or more polypropylene homopolymers. This allows for adjustment of the processing conditions during spinning.

The fibers may be staple fibers or chopped fibers. This is beneficial for making nonwovens and geotextiles with good tenacity.

The spun drawn fiber may have an average MFI of 2 to 4 g/10 min measured according to ISO1133 for polypropylene. This narrower range allows more control over the extrusion and spinning process.

The spun drawn fiber may have a multilobal cross-section or, preferably, a trilobal cross-section. These cross sections allow for the production of improved nonwovens with good elongation, tensile strength and coverage.

the spun drawn fibers may be multicomponent fibers, for example, preferably bicomponent fibers. These fibers produce better bond strength by heat treatment to produce a nonwoven with better properties.

The polypropylene composition of embodiments of the present invention may form the core of a multicomponent fiber. Thus meaning that the core can be left intact after heat treatment to bind the fibers in a nonwoven such as a geotextile.

The fibres have a titre of at least 1dtex and at most 100 dtex. This range applies to nonwovens such as geotextiles.

The polypropylene composition of the spun drawn fiber comprises the first polymer and the second polymer as a blend or multimodal polymer composition. This allows to obtain a balanced performance and optionally improves the processing during extrusion and spinning.

Another aspect of the present invention provides a nonwoven fabric comprising the spun drawn fibers of an embodiment of the present invention. The nonwoven fabric may be a geotextile.

In another aspect, embodiments of the present invention provide a method for preparing a spun drawn fiber, comprising the steps of:

a) Feeding the polypropylene composition to an extruder;

b) Melt spinning the polypropylene composition from a plurality of openings to form molten filaments; and

c) Cooling the molten filaments obtained in step (b) to obtain solidified fibers.

In this method, the fiber may be drawn at a draw ratio of 2 to 4 (e.g., 2.5 to 4).

Another aspect of the present invention provides a polypropylene composition of a polypropylene homopolymer having an MFI of 1 to 3 g/10 min measured according to ISO1133 and a xylene solubles content of 1 to 4.5 wt.%, or 1.5 to 4.5 wt.%. The xylene soluble content is in the range of 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 1 wt% to 2.5 wt%, or 1.5 wt% to 2.5 wt%.

The polymer temperature in the extruder (measured at the extruder outlet) and/or the polymer temperature in the spinning beam may be in the range 255 ℃ to 350 ℃, preferably in the range 265 ℃ to 340 ℃, more preferably in the range 275 ℃ to 330 ℃, most preferably in the range 285 ℃ to 320 ℃.

Such polypropylene compositions are suitable for providing spun drawn fibres with the following properties: an elongation of at least 65% as measured according to ISO 5079 at an 80 mm/min tuned test rate and/or an average toughness/tensile strength of at least 56cN/tex as measured according to ISO 5079 at an 80 mm/min tuned test rate. The average toughness/tensile strength may be, for example, in the range of 56 to 70cN/tex, and has an elongation at break of 75 to 90%.

The polypropylene composition is composed of one or more polypropylene homopolymers. For example, the polypropylene composition may comprise a first polymer and a second polymer, the polypropylene composition being a blend or a multimodal polymer composition.

The polypropylene composition of the present embodiments may be used in the manufacture of bicomponent fibers. The bicomponent fiber may include a core and an outer layer (e.g., like an outer layer) covering part or all of the circumference of the coreLeather) Wherein the polypropylene composition is used to form a core. The high tensile strength and high elongation of the polymer composition of the core is such that the core of the bonded spun drawn fiber is retained after the fiber is bonded in a nonwoven, such as a geotextile.

The embodiment of the invention has the advantages that: the mechanical properties of the fibers or of the nonwovens produced from the fibers are improved. Further advantages of at least some embodiments are: improved mechanical properties can be obtained while maintaining the yield and productivity of the fiber production.

the spun drawn fibers of embodiments of the present invention can be used in woven products, or nonwoven products (e.g., dry or wet wipes), hygiene products, filters, carpets, upholstery, and other textiles, for example, in automotive industry articles made with such nonwoven structures, or in construction and agricultural articles, geotextiles, hygiene and medical articles. These articles serve functions such as filtration, reinforcement, separation, drainage and/or protection.

The spun drawn fiber of any or all embodiments of the present invention preferably does not comprise a slit ribbon.

The embodiment of the invention has the advantages that: the weight of the nonwoven structure, for example, for use as or in carpets, upholstery, absorbent wipes, or geotextiles, can be reduced while still obtaining the same performance. Further advantages of embodiments of the invention may be: reducing the manufacturing cost of the final product, reducing the impact on the environment, and making the operation easier.

Embodiments of the present invention comprise a first polymer that is a polypropylene homopolymer having a xylene solubles content in the range of from 1 wt% to 4.5 wt%, or in the range of from 1.5 wt% to 4.5 wt%, relative to the weight of the polypropylene homopolymer; preferably in the range of 1 wt% to 2 wt%, or in the range of 1 wt% to 3 wt%, or in the range of 1.5 wt% to 3.5 wt%; most preferably in the range of 1 wt% to 2.5 wt%, or in the range of 1.5 wt% to 2.5 wt%. The MFI of the polypropylene homopolymer is 1-3 g/10 min, preferably 1.5-2.5 g/10 min.

In an embodiment, the polypropylene composition comprises a blend of the aforementioned first polymer and a second polymer which is a polyolefin, such as polypropylene or polyethylene, in an amount of at least 0.1 wt%, preferably 0.5 to 5 wt%, relative to the total weight of the polypropylene composition.

In another embodiment, the polypropylene composition (with or without the second polymer) comprises an additive, e.g. a Polymeric Processing Agent (PPA) acting as a processing aid, in an amount of at least 0.01 wt. -%, preferably 0.01 to 0.1 wt. -%, relative to the total weight of the polypropylene composition. By means of such processing aids, it is possible to achieve a reduction of the pressure and temperature in the extruder and in the spinneret die during spinning. Both the additive and the second polymer may be used separately, or applied simultaneously, for example.

The second polymer may be a polypropylene homopolymer. The second polymer may be a polyolefin having a second MFI (determined according to ISO1133 or ASTM D-1238) higher than the first MFI, preferably significantly higher than the first MFI. For example, the MFI of the second polymer may be at least 10 times, 20 times, or even 30 times higher than the MFI of the first polymer. The second polymer may have an MFI of less than 100 g/10 min and form a blended composition as a melt (in the melt) with the first polypropylene polymer and not have multiple phases.

The second polymer is present in the polymer blend in an amount of at least 0.5 wt%, preferably in the range of 1 to 5 wt%, relative to the total weight of the polymer blend. The second polymer forms a single phase composition with the first polypropylene in melt form.

The polypropylene composition may further comprise additives such as antioxidants or UV blockers in an amount preferably in the range of 1000 to 2500ppm (or more) by weight of the polypropylene composition.

Preferably, the additive or the second polymer is mixed with the first polymer in the melt, for example when melted in the extruder barrel. Without being limited by theory, the additive or the second polymer acts as a lubricant or as a processing aid that reduces the pressure and/or temperature of the extruder and spinneret, which are required to meet the conditions for extruding a polymer having a higher viscosity through the large number of holes of the spinneret die.

A low melt flow index means a high molecular weight and therefore a high viscosity polymer. High melt flow index means low molecular weight and therefore low viscosity polymers. Due to the fact that polymers, such as PE and PP, are measured at different temperatures, the MFI values cannot be directly compared at extrusion, which means that the extrusion temperature of PP at extrusion is at an elevated temperature. For example, the apparent viscosity change between extrusion temperatures of 240 ℃ and 270 ℃ may be about 3 times that of the polyolefin, and therefore, when considering whether a polymer can function as a low viscosity extrusion processing aid, a number of factors must be considered, such as MFI, extrusion temperature, shear rate, and some aspects of the polymer such as branching and chain entanglement.

thus, in a blend of a first polypropylene homopolymer and a second polyolefin polymer, the melt flow indices of the first polymer and the second polymer can be tailored to achieve the advantage of reducing extrusion pressure and/or temperature. For example, if the second polymer is polyethylene, the MFI of the polyethylene can be as low as 3 g/10 min or less due to the reduced viscosity of the PE when extruded at PP temperature. If the second polymer is PP or a polymer with a melting point similar to PP, 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 the melt flow index of the first polymer is preferably at least 10 and may be in the range of 10 to 30.

other embodiments of the invention include the following polymer compositions: comprising a combination of polymers such as polypropylene and polyolefin, the xylene solubles content of the composition preferably being 1 to 4.5 wt.%, or 1.5 to 4.5 wt.%, and having an MFI of 1 to 3 g/10 min, preferably 1.5 to 2.5 g/10 min. The xylene solubles content may be in the range of 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 having an MFI of about 2 g/10 min may be mixed with 20% of a PP homopolymer having an MFI of about 4 g/10 min. When the ratio is determined according to ISO1133-1 for PP: 2011 or ASTM D-1238 standard, the resulting polypropylene composition has a melt flow index between 2 and 4, i.e., less than 3 grams/10 minutes. A processing agent or additional polymer may be added to the blend to reduce the temperature and pressure 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), thus when blended according to ISO1133-1 for PP: 2011, the polypropylene composition has a Melt Flow Index (MFI) of less than 3 grams/10 minutes and a xylene solubles content in the range of 1 wt% to 4.5 wt% or in the range of 1.5 wt% to 4.5 wt%. The xylene soluble content may be in the range of 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 in the range of 1.5 wt% to 2.5 wt%.

the first polymer and/or the second polymer may be prepared using a suitable catalyst, for example a ziegler-natta catalyst or a metallocene catalyst.

The first polymer preferably exhibits one or more of the following properties:

i. A xylene soluble content in the range of 1 to 4.5 wt.%, or in the range of 1.5 to 4.5 wt.%; preferably in the range of 1 to 2 wt.%, or in the range of 1 to 3 wt.%, or in the range of 1 to 3.5 wt.%, or in the range of 1.5 to 3.5 wt.%, most preferably in the range of 1 to 2.5 wt.%, or in the range of 1.5 to 2.5 wt.%; and

When the ratio is in accordance with ISO1133-1 for PP: 2011 or ASTM D-1238, a melt flow index of less than 3.0 dg/min, more preferably 1.5 to 2.5 g/10 min.

The polypropylene composition of the present invention can be spun and drawn into High Tenacity (HT) fibers. The drawn fibers of embodiments of the present invention comprise filaments made from the polypropylene composition of any of the embodiments of the present invention, the titer of the filaments being for example at least 1dtex and at most 100dtex, preferably at least 2dtex and at most 30dtex, most preferably at least 3dtex and at most 10 dtex.

The spun drawn fibers are useful, for example, in nonwoven structures for a variety of applications, one of which is geotextile applications. These High Tenacity (HT) fibers made using the polymer composition have superior performance over currently available PP fibers, such as:

Elongation (average): at least 65%, preferably 65 to 100%, more preferably 70 to 90%, and still more preferably 75 to 85%. The individual fibers may vary significantly outside of these average values, for example, between 20% and 150%. Thus, the narrower range is the average determined according to ISO 5079 at an 80 mm/min adjusted test rate.

Improved toughness (tensile strength): at least 56cN/tex, preferably in the range of 56 to 70cN/tex, more preferably in the range of 58 to 66cN/tex, determined according to ISO 5079 at a 80 mm/min adjusted test rate. For example, a breaking elongation in the range of 75 to 90% can be achieved. These values are averages of multiple fibers and individual fibers can be well outside of these ranges.

The spun drawn fiber has an MFI (average from a number of fibers) after extrusion of 1-5 g/10 min, according to ISO1133-1 for PP: 2011 or ASTM D-1238. The slight change in MFI before and after extrusion indicates that a lower level of degradation occurs when the polymer composition of embodiments of the present invention is used to produce drawn fibers.

the xylene solubles content of the extruded polymeric material in such spun drawn fiber is in the range of 1 to 4.5 wt.%, or in the range of 1.5 to 4.5 wt.%, relative to the weight of the polypropylene homopolymer; preferably in the range of 1 wt% to 2 wt%, or in the range of 1 wt% to 3 wt%, or in the range of 1 wt% to 3.5 wt%, or in the range of 1.5 wt% to 3.5 wt%, most preferably in the range of 1 wt% to 2.5 wt%, or in the range of 1.5 wt% to 2.5 wt%.

The fibers of embodiments of the present invention may be solid or hollow and/or round or shaped and/or mono-or multi-component. Shaped fibers include multilobal fibers, such as bilobal and trilobal fibers. The multicomponent fibers include bicomponent fibers.

Further, nonwoven structures comprising such fibers are disclosed. Nonwoven structures may be made using at least some of the above-described fibers. Geotextiles can be produced using the novel fibers, for example, in the form of needle felt:

The tensile strength of the needled felt is increased by at least 5% (e.g., 8%, 10%) over the state of the art. The elongation of the needled felt is also very satisfactory, i.e., there is no degradation in performance.

In addition, a geotextile made using such fibers or such nonwoven structures is disclosed. In addition, the invention also discloses a needle felt (needle felt). By using the fibers of the present embodiments, the tensile strength of the needled felt is increased as compared to the state of the art.

In addition, the present invention provides a method for preparing high tenacity fibers. For example, one suitable method for making fibers of embodiments of the present invention includes the steps of:

a) The polypropylene composition according to any of the embodiments of the present invention is fed to an extruder and the extruder temperature (measured at the extruder outlet) may be in the range of 255 ℃ to 350 ℃, preferably in the range of 265 ℃ to 340 ℃, more preferably in the range of 275 ℃ to 330 ℃, most preferably in the range of 285 ℃ to 320 ℃.

b) Melt spinning the polypropylene composition by advancing the polymer composition through a die having a plurality of openings to form molten filaments;

c) Cooling the molten filaments obtained in step (b) to obtain solidified fibres; and preferably

d) drawing the cured fiber at a temperature of at least 70 ℃ and up to 150 ℃ and at a draw ratio of at least 2 (preferably 2.5 to 4) to obtain a fiber having:

Improved toughness (tensile strength): at least 56cN/tex, preferably in the range of 56 to 70cN/tex, more preferably in the range of 58 to 66cN/tex, determined according to ISO 5079 at a 80 mm/min adjusted test rate. These are averages of multiple fibers and individual fibers can be well outside of these ranges. The average toughness/tensile strength may be in the range of 56 to 70 cN/tex; and has a breaking elongation of 75-90%.

The spun drawn fiber may be made into a textile product or a nonwoven fabric (e.g., geotextile) by a conventional method.

Definition of

In the present application, the terms "polypropylene" and "propylene polymer" may be synonymous. Unless otherwise defined, the expression "percent by weight" or "wt%" (weight percent) herein and throughout the specification refers to the relative weight of the respective component to the total weight of the formulation. The polypropylene used in the present invention can be prepared by polymerizing propylene in the presence of a suitable catalyst, for example a ziegler-natta catalyst or a metallocene catalyst, as known to those skilled in the art.

The term "fiber", such as the term "spun drawn fiber" refers to a fiber according to any or all embodiments of the present invention, preferably excluding slit ribbons. The fibers of any embodiment of the present invention may be short fibers of several centimeters in length, for example 20 to 120 millimeters in length or up to 300 millimeters in length, or may include chopped fibers of 2 to 25 millimeters in length.

The "nonwoven structure" used in the present invention may comprise fibers of any embodiment of the present invention, for example, staple fibers of several centimeters in length, for example 20 to 120 millimeters in length, or up to 300 millimeters. The non-woven structure can also be made of 2-25 mm short-cut fibers, such as pure fibers or mixed fibers.

The term "needling" refers to a nonwoven structure which is consolidated by passing the nonwoven through one or more needle boards having thousands of needles which repeatedly penetrate the nonwoven fabric to form a mechanically entangled structure.

For example, "geotextiles" and "landscape textiles" are used to cover the floor area. Geotextile as used in this application relates to a fabric made from a nonwoven structure. They are applicable in the field of civil engineering, for example, roads, airports, railways, dykes, supporting structures, reservoirs, canals, dams, bank protection, coastal engineering for controlling shoreline erosion, and agriculture and landscape protection for moisture retention, water conservation, weed or lawn suppression, soil warming and light reflection. The geotextiles or landscape textiles of the present embodiments are typically supplied in roll form and simply unrolled to cover a floor area.

Test method

Melt Index (MI), Melt Flow Index (MFI), or Melt Flow Rate (MFR) means a melt flow rate according to ISO 1133-1: 2011 or ASTM D-1238, the grams of melt to push out every 10 minutes from a mold of a specified size under a specified load. For PP, the load is 2.16kg, the die size D is 2.095mm, and L is 8 mm. The experiment was carried out at 230 ℃. (for PE, the same load and size of the mold was used, but the experiment was performed at 190 ℃).

Examples of suitable methods for determining the xylene solubles (% XS) are, preferably performed twice:

weigh 4+/-0.1 grams of polymer in Erlenmeyer flask

Addition of 200 ml of inhibited and degassed xylene

Heating under nitrogen flow with stirring, fractional distillation to complete dissolution (+/-45 minutes)

cooling for 15-20 minutes

-cooling the flask in a thermostatic bath at 25+/-0.1 ℃ for 45 minutes

-filtering the contents of the erlenmeyer flask using a Whatman (Whatman) n ° 2V filter paper

Removing 100ml of filtrate on a weighed aluminum pan

-evaporating the solvent on a hot plate under nitrogen (about 130 ℃), under nitrogen

After complete evaporation, the tray is placed in a vacuum oven at 105 ℃ for 30 minutes

Cool for 1 hour and weigh.

The percentage of xylene solubles ("XS") was calculated according to the following formula:

XS% (in weight) — 100 × [2 × ((mass of tray and raffinate) - (mass of empty tray)) - (mass of raffinate assuming any blank xylene sample) ]/(mass of polypropylene polymer sample), all weights being expressed in the same units, e.g. in grams.

Detailed Description

Polymer blends or bimodal polymers

the spun drawn fiber of some or all embodiments of the present invention is prepared from a polymer composition that may comprise a homopolymer, a polymer blend, or a polymer having a multimodal fraction. The polypropylenes used in the present invention are prepared by polymerizing propylene in the presence of a suitable catalyst, such as a ziegler-natta catalyst or a metallocene catalyst, as are well known to those skilled in the art. The polypropylene polymer is preferably prepared by polymerization in propylene at a temperature in the range of from 20 ℃ to 100 ℃. Preferably in the range of 60 ℃ to 80 ℃. The pressure may be atmospheric or higher, preferably between 25 and 50 bar.

Preferably, the polymer blend of some embodiments of the present invention comprises a first polypropylene homopolymer and a second polyolefin polymer, the first polypropylene homopolymer having an MFI of less than 3 and preferably between 1 and 2.5 grams/10 minutes, the MFI being in accordance with ISO 1133-1: 2011 or ASTM-1238, condition L, using a 2.16kg load and a temperature of 230 ℃. If the second polymer has a melting temperature lower than that of PP, as is the case with polyethylene, the MFI of this second polymer may be similar to that of PP, for example for the conditions of polyethylene, according to ISO 1133-1: an MFI of less than 3 g/10 min as measured by 2011 or ASTM-1238. This is because the MFI is measured at two different temperatures, i.e. for PE compositions the temperature is lower than for PP compositions (190 ℃ for PE and 230 ℃ for PP). PE is present in the extruder at the melting temperature of PP, which means that the viscosity of PE is reduced. If the second polymer is PP, it preferably has a higher melt flow index, wherein the ratio of the melt flow index of the second polymer to the melt flow index of the first polymer is preferably in the range of 10 times or more, 20 times or more, 30 times or more, 40 times or more, or 50 times or more and less than 100 times. If the second polymer is PP, the MFI of the second polymer may be at least 20 g/10 min, at least 30 g/10 min, at least 40 g/10 min, at least 50 g/10 min, at least 60 g/10 min, at least 70g/10 min, and less than 100 g/10 min. The polypropylene composition may further comprise an antioxidant. The antioxidant may be present in the range of 1000 to 2500ppm or more based on the weight of the first polymer.

The processing aid preferably does not affect the elongation/tensile properties of the spun drawn fiber to any significant extent.

The first polymer is a polypropylene homopolymer. The optional second polymer is preferably miscible with the first polymer when molten, e.g., in an extruder prior to spinning. It is therefore preferred if the second polymer is a polyolefin, such as polypropylene or polyethylene. The first polymer (i.e., polypropylene homopolymer) and the second polymer may be mixed together in pelletized, fluff, or powder form prior to introduction into the extruder. Alternatively, the polymers may be introduced separately into the extruder at one or more locations so that the polymers are thoroughly mixed within the extruder feeding the spinneret. Alternatively, the polymers may be introduced into different extruders. The additives may be melted in a separate (e.g., smaller) side extruder and then mixed in the main stream in a mixing zone at the end of the main extruder, or mixed by a static mixer after the extruder. The temperature in the extruder (measured at the extruder outlet) may be in the range of 255 ℃ to 350 ℃, preferably 265 ℃ to 340 ℃, more preferably 275 ℃ to 330 ℃, most preferably 285 ℃ to 320 ℃.

A 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, for example by varying the amount of hydrogen injected into the polymerization reactor. Peroxides can be used to reduce the molecular weight of materials with too high a molecular weight. This can be set to a specific MFI by starting with a PP with a lower MFI than the ultimately required MFI and then using a peroxide to increase the MFI, for example by reactive extrusion.

In one embodiment of the invention, instead of a blend of the first polymer and the second polymer, the first polymer may be bimodal or multimodal and may comprise at least two polypropylene homopolymer fractions of different molecular weight. The bimodal or multimodal polymer should have a melt flow index of less than 3 g/10 min, preferably in the range of 1 to 2.5 g/10 min, according to ISO 1133-1: 2011 or ASTM-1238, condition L, using a load of 2.16kg and measured at a temperature of 230 ℃. Such bimodal polypropylene homopolymer is preferably produced in a polymerization unit having two reactors in series. In this sequential arrangement of polymerization reactors, the polypropylene homopolymer withdrawn from one reactor is transferred to another reactor following in series, where the polymerization is continued. In order to produce polypropylene homopolymer fractions having different indices, the polymerization conditions in the individual polymerization reactors need to be different, for example the hydrogen concentration or the peroxide concentration in the two polymerization reactors.

Whether a blend or multimodal split is selected, the first and second polymers are preferably in a single phase when molten.

Generally, the higher the molecular weight, the higher the tensile strength and modulus of the spun drawn fiber. However, decreasing the MFI means that the material becomes more viscous, which will increase the pressure in the extruder and spinneret dies. These portions of negative impact on extrusion and melt spinning of polymeric materials can be offset by lowering the high viscosity by, for example, increasing the temperature under normal operating conditions. In order to minimize the degradation caused by this higher temperature, it is preferred to add higher amounts of antioxidant in the polymer composition.

In addition to the above MFI and antioxidants, the first polymer preferably has the following properties: the percentage of atactic material is less than 5%, preferably between 1.5 and 2% by weight, for example between 1.6 and 1.8% by weight, based on the total weight of the first polymer, measured as xylene solubles content.

Gel count is an indicator of product homogeneity and is preferably negligible.

The chemical structure of a polymer may be defined as atactic, isotactic or syndiotactic. These refer to the ideal sequence of the steric arrangement of the methyl groups in the polymer. This 3-dimensional orientation and order will determine how the polymer molecules are aligned by folding, crystallization, etc. Atactic means that the methyl groups are randomly arranged and therefore do not fold symmetrically and look like a sticky product (glue). Isotactic means that all methyl groups are located on the same side of the polymer chain, so that the molecules can fold in a symmetrical manner and take the form of crystals. For syndiotactic products, the methyl groups are on alternating sides each time. In any practical polymer, "artifacts" occur with catalyst polymerizations.

Laboratory analysis can be used to extract or spectrally determine the number of these different polymer arrangements. In the case of extraction, heptane solubles or insolubles or xylene solubles or insolubles may give an atactic content. Low molecular weight polymers, if present, can also be extracted and counted as atactic materials. Extraction efficiency is also limited, which makes not all atactic polymers to be measured. The same uncertainty of the determination also occurs in the case of spectroscopic analysis (NMR/near infrared/X-ray diffraction).

Fiber production

An apparatus for spinning melt spun fibers of embodiments of the present invention may include a spinning beam. A spinning beam is known from US patent application US2004/0124551, which is incorporated herein by reference. The polymer melt from the extruder is fed to the spin beam and distributed within the spin beam to a plurality of spin cans mounted on the spin beam. The extruder and spinning beam are equipped with heaters. The temperature in the extruder (measured at the exit of the extruder) and/or the temperature of the spinning beam is in the range 255 ℃ to 350 ℃, preferably 265 ℃ to 340 ℃, more preferably 275 ℃ to 330 ℃, most preferably 285 ℃ to 320 ℃.

The manufacturing method of the embodiment of the invention comprises the following steps:

1) Compounding the amounts of the first polymer and optionally the second polymer or other polymers of embodiments of the present invention, which polymers further comprise an antioxidant and optionally other pigments and/or other additives;

2) Extrusion melting, mixing, pressurizing, and pressurizing and extruding the polymer material in the form of filaments through a spinneret die;

3) Quenching the filaments from the molten material into solid filaments;

4) During step 2) and step 3), the filaments are drawn for a first time ("melt drawing");

5) Coating a spinning oil agent: improve antistatic properties and reduce wear. This results in stable processing during fiber production and nonwoven production. Additional spin finishes are typically added late in the process (e.g., after cutting texturing-see below);

6) Drawing is performed by drawing the solidified filaments to obtain good tensile strength by increasing orientation. The draw ratio of this step is used to characterize how much filament is drawn. The fibers are conventionally drawn in one or two steps; some manufacturers also provide equipment that allows the fiber to be drawn in many small steps. It is assumed that many small steps can be described as a single final draw ratio. In this process, the fiber is heated using an oven. This reduces the required tensile force and may improve the final properties;

7) and (3) stabilizing: a stabilization step may be added to the process to reduce internal stresses within the fibers, thereby reducing shrinkage;

8) Texture (texture): the filaments are crimped/textured to increase the bulkiness and cohesion of the fiber. The fibers may be treated with steam prior to the texturing step to improve the process;

9) Optional secondary spin finish operation: after drawing the fiber, a second spin finish application, optionally crimping or texturing, is optionally performed. Steam treatment for better texture is preferred because some spin finish can be removed during texture;

10) The fibers are optionally cut to lengths, for example, 20mm to 300mm to form staple fibers, or cut to 2 to 24mm chopped fibers.

alternatively, a two-step process may be used in which the material is collected between a quench step and a draw step. In the two-step process, steps 1 to 3 are not linked to the rest of the processing. After quenching in step 3), the filaments are collected in a bin or on a spool. The advantage of this process is that the first step can be carried out at higher spinning speeds. The main drawback of this approach is the additional workload.

Additionally, some additional steps may be included in both the one-step and two-step processes. These additional steps may be, for example, a relaxation step or a curling step.

The first polypropylene polymer preferably used for the preparation of the high tenacity fibers has a low XS value and a low MFI. This makes the fiber stronger but results in more difficult spinning processes, e.g. when the% XS is low and the extrusion temperature and pressure are higher corresponding to a low MFI, the filaments tend to break more easily during spinning.

Embodiments of the present invention avoid these problems while maintaining high toughness and elongation. Considering the case where a conventional polypropylene homopolymer having an MFI of 4 g/10 min and a low XS of 1.5-2.5% can be used as a fiber for geotextiles, an attempt to improve the performance of the fiber was made by further reducing one or both of MFI and XS which cause spinning problems (e.g., high pressure, high temperature, polymer degradation, damage to spinning equipment, etc.).

For example, if the spinning apparatus used to spin PP with an MFI of 2 g/10 min is the same as the apparatus used to spin commercial PP fiber grades with an MFI in the range of, for example, 4-25 g/10 min, a sharp increase in pressure may lead to damage to the equipment (extruder and spinneret) or an emergency stop of the machine and possibly even degradation of the polymer in a short time (e.g., a few minutes).

When using a polypropylene homopolymer of the first polypropylene of embodiments of the present invention (e.g., having a low MFI (e.g., less than 3 g/10 min, such as in the range of 1 to 2.5 g/10 min) and a low XS (e.g., in the range of 1 to 2.5 wt.%, or 1.5 to 2.5 wt.%, or 1 to 2 wt.%, or 1 to 3 wt.%), it is preferred to take some precautions:

a) The temperature of the extruder and spinning beam is increased, e.g. by 10 ℃, 20 ℃, 30 ℃ or 40 ℃ or even more, e.g. from 245 ℃ to 275 ℃, while preferably below 350 ℃, below 320 ℃, preferably below 295 ℃, preferably below 290 ℃, e.g. in the range 275 ℃ to 330 ℃, or 285 ℃ to 320 ℃.

b) The spin pump output rate is reduced, for example, by 10% or 20%.

c) The second polymer is included in the blend with the first polymer or as a multimodal or bimodal polymer, which acts as a processing aid. If the second polymer is polypropylene, the second polymer preferably has a higher (10, 20 or 25 times higher) MFI (e.g., an MFI of 50 g/10 min) than the first polymer. The MFI range of the second polymer may be at least 20 grams/10 minutes, at least 30 grams/10 minutes, at least 40 grams/10 minutes, at least 50 grams/10 minutes, at least 60 grams/10 minutes, at least 70 grams/10 minutes, and may be less than 100 grams/10 minutes. If the second polymer is polyethylene, its MFI may be the same as that of the first polymer.

d) Known internal and external lubricants may be used. Internal lubricants generally exhibit some external lubrication.

It is believed that the internal lubricant reduces the friction that occurs between the polymer molecular chains, thereby reducing the melt viscosity. They may be polar materials.

External lubricants primarily reduce wall adhesion between the polymer and the metal surface. Most of which are non-polar materials such as paraffin or polyethylene. This external lubrication is affected by hydrocarbon chain length, branching or functional groups. However, these known lubricants have a low molecular weight and have an effect on the MFI of the extruded polymer composition.

In contrast to these known lubricants, a blend or multimodal composition of the first polymer with a low MFI of the present embodiments is provided. The second polymer is present in an amount less than 5% of the polymer composition, such as 1-5%, 2-3%, or 2.5%. If the second polymer is polypropylene, the second polymer preferably has a higher (e.g. 10-fold, 20-fold or 25-fold) MFI than the first polymer, e.g. a MFI of 50 g/10 min. The MFI range of the second polymer may be at least 20 grams/10 minutes, at least 30 grams/10 minutes, at least 40 grams/10 minutes, at least 50 grams/10 minutes, at least 60 grams/10 minutes, at least 70 grams/10 minutes, and may be less than 100 grams/10 minutes. For multimodal compositions of polymer combinations, for example, a combination of a polypropylene with an MFI of 2(80 wt%) and a polypropylene with an MFI of 4(20 wt%) may be used, which results in a polymer with an MFI of less than 3, for example between 1 and 2.5. Fibers of embodiments of the present invention can be made with 100% of the first polymer (without the second polymer), but this may reduce the spinning rate.

Other additives may be blended with the first polymer, or may be blended with the first polymer and the second polymer to reduce the pressure build-up, including the polymer processing aid.

Other additives may be, by way of example, antioxidants, UV flame retardants, light stabilizers, acid scavengers, flame retardants, lubricants, antistatic additives, nucleating/clarifying agents, colorants. A summary of these Additives can be found in Plastics Additives Handbook, ed.h. zweifel, 5 th edition, 2001, hanse press. The antioxidant may be selected from the group consisting of phosphites, hindered phenols, hindered amine stabilizers, and hydroxylamines. Alternatively, phenol-free antioxidant additives are also suitable, such as those based on hindered amine stabilizers, phosphites, hydroxylamines, or any combination thereof.

Properties-shape of the fiber

The fibers of embodiments may be solid round, hollow round, solid shaped, or hollow shaped, such as multilobal, bi-lobal, or tri-lobal fibers, bicomponent fibers of any of these shapes (e.g., bicomponent solid round, bicomponent hollow round, bicomponent solid shaped, or bicomponent hollow shaped, such as bicomponent multilobal, bicomponent bi-lobal, or bicomponent tri-lobal fibers). The spun drawn fiber of any or all embodiments of the present invention preferably does not comprise a slit ribbon.

Fibers for use in nonwoven structures may be made from polymers catalyzed by metallocene catalysts according to embodiments of the present invention. Such fibers can BE spun into bicomponent fibers by the method described in Belgian patent application BE 2016/5213 entitled "nonwoven structures having fibers catalyzed by metallocene catalysts," which is incorporated herein by reference in its entirety. The bonded and entangled nonwoven structures may be used, for example, in hygiene and wellness products (e.g., for replacement or disposable products, such as may be used in hospitals, schools, and homes), diapers, or wet wipes, but may also be used in carpets made using such nonwoven structures. The mechanical properties of the geotextile or upholstery nonwoven structure can be improved by adding such metallocene bicomponent fibers for better bonding. The amount of metallocene bicomponent fiber used in the nonwoven may be in the range of 5% to 100% of the fiber from which the nonwoven is made.

The tensile properties of the nonwoven, e.g. a needle felt made from these fibers, are improved if the core of such bicomponent fibers is preferably made from the first polypropylene polymer of the embodiment of the invention having a low MFI, or a blend of the first polymer and the second polymer of the embodiment of the invention, or a multimodal composition of the first polymer and the second polymer of the embodiment of the invention. On the other hand, bicomponent fibers having such a low MFI made from the polypropylenes of embodiments of the present invention are used as a sheath or sheath for bicomponent fibersleatherThe case of the material is not preferable because when the polypropylene is used in addition to the polypropyleneleatherMelting results in bonding with adjacent fibers, which reduces the tensile properties.

another embodiment of the invention comprises a bicomponent fiber with a core made of the first polypropylene polymer of the embodiment of the invention having a low MFI, or a blend of the first polymer and the second polymer of the embodiment of the invention, or a multimodal composition of the first polymer and the second polymer of the embodiment of the invention. The outer layer polymer material of the bicomponent fiber is preferably made of a polypropylene polymer having a melting temperature lower than that of the core material prepared using a metallocene catalyst. Such bicomponent fibers can be used in a variety of applications, such as in the production of nonwovens for use in geotextiles or upholstery. Nonwovens made with such bicomponent fibers may have the advantage of additional stiffness and better formation stability. Embodiments of the present invention provide in one aspect a bonded and entangled nonwoven structure wherein the bonded and entangled nonwoven structure is made of at least 50% by weight of chopped or staple fibers and the fibers of the nonwoven structure are at least partially bonded, said at least partial bonding comprising heat activated bonding between a first polypropylene composition having an MFI of less than 3 grams/10 minutes and a second outer layer material made using at least one metallocene catalyst and having a melting point of at least 10 ℃ lower than the melting point of the first polypropylene composition, the weight of the second material in the nonwoven structure being at least 3% of the weight of the nonwoven structure.

The fibers of embodiments of the present invention having an external trilobal shape and which may be hollow or solid fibers may be made from polypropylene polymers.

The shape of the fibers affects the mechanical properties, in particular the permeability to air and water. Such trilobal fibers may be modified for geotextiles or filters. For example, a trilobe shape may increase contact surface, which may increase bond strength or filtration characteristics and better contact between building materials (e.g., between concrete and a fiber or nonwoven structure made by embodiments of the present invention).

the trilobal shape may also improve the coverage of the carpet or upholstery, for example, using a conventional basis weight to achieve better coverage or at a lower weight to achieve the desired coverage.

The fibers of the present embodiments may be ofOuter coverLeatherAnd a core, wherein the core comprises the polypropylene composition of the present invention, and wherein the outer core comprisesLeatherMay comprise a polyolefin (e.g., PE or PP, preferably PP) catalyzed by a metallocene catalyst, the bicomponent fiber preferably having an outer trilobal shape. Which combines a number of advantages and may find use in upholstery or geotextiles.

Fiber Properties-mechanical Properties

the measured properties of the fibers of the embodiments of the invention were improved compared to fibers made on the same line with Total 4069 polypropylene (MFI 4 g/10 min) or with polycim HL10XF polypropylene (MFI 3.5 g/10 min):

the fibers of embodiments of the invention (e.g., for 4.4dtex) exhibit higher tenacity, e.g., greater than 56 or 58cN/tex (e.g., 62cN/tex), and maintain elongation.

The fibers of embodiments of the invention achieve the following properties:

elongation (average): at least 65%, preferably between 65 and 100%, more preferably between 70 and 90%, and more preferably between 75 and 85%. The individual fibers may vary significantly outside of these average values, for example between 20% and 150%. The narrower range is therefore the average determined according to ISO 5079 and using a test rate adjusted at 80 mm/min.

improved toughness (tensile strength): at least 56cN/tex, preferably in the range of 56-70 cN/tex, more preferably in the range of 58-66 cN/tex, determined according to ISO 5079 using a test rate adjusted at 80 mm/min. These are average values of the fibers, and the individual fibers may well exceed these average values. The average toughness/tensile strength may be in the range of 56 to 70cN/tex and have an elongation at break of 75 to 90%.

Preparation of needled nonwoven structures

The nonwoven structure of an embodiment of the invention can comprise fibers of any embodiment of the invention, for example, fibers made from a first polymer that is a polypropylene homopolymer having an MFI of between 1 and 2.5 grams/10 minutes, and a xylene solubles content in the range of 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 of from 1 wt% to 2 wt%, or from 1 wt% to 3 wt%, from 1 wt% to 3.5 wt%, or from 1.5 wt% to 3.5 wt%, most preferably in the range of from 1 wt% to 2.5 wt%, or from 1.5 wt% to 2.5 wt%, relative to the weight of the polypropylene homopolymer; and the shape of the fibers may be any of solid round, hollow round, multilobal solid or multilobal hollow (e.g., trilobal solid or trilobal hollow), bicomponent solid round or bicomponent hollow round, or multilobal bicomponent hollow or solid (e.g., bicomponent trilobal solid or hollow), any of which may be optionally crimped. Any of such fibers can have an elongation (e.g., for 4.4dtex) of greater than 65% and a tenacity (e.g., for 4.4dtex) of greater than 56cN/tex, while also maintaining higher elongation. The polymer composition used to make any of these fibers may be a blend or a multimodal composition. In a blend, a first polymer of an embodiment of the invention has an MFI of less than 3 g/10 min, and less than 5% (e.g., 1-5%, 2-3%, or 2.5%) of a second polyolefin polymer (e.g., PE polymer), the MFI of the PE polymer being similar to the MFI of the first polymer, or the MFI of the polypropylene polymer being greater than the MFI of the first polymer, e.g., by a factor of 10, 20, or 25. The MFI of the second PP polymer may range from at least 20 g/10 min, at least 30 g/10 min, at least 40 g/10 min, at least 50 g/10 min, at least 60 g/10 min, at least 70g/10 min, and may be less than 100 g/10 min.

The nonwoven structure may be entangled, for example, by needling or hydroentanglement. These fibers may be spread in a uniform web by an airlaid process, for example, for making nonwoven structures for use in mats, scrims, sheets, and the like. The nonwoven structure may be made by needle punching. These fibers may be bundled, placed on a conveyor belt and dispersed, for example, spread in a uniform web by a wet-laid, air-laid, or carded/cross-lapped process.

the nonwoven structures of embodiments of the present invention may be made by calendering thermal bonding techniques. For example, the carded yarns comprising bicomponent fibers of any embodiment of the present invention may be subjected to the pressure and temperature of a calender. Alternatively, the nonwoven structures of embodiments of the present invention may be manufactured by air-through bonding technology. In this process, the carded yarns comprising bicomponent fibers of any of the embodiments of the present invention are subjected to hot air.

nonwoven structures according to embodiments of the present invention may have a basis weight of between 10 (or 12) gsm and 170gsm in some applications (e.g., carpet, gauze, wool, hygiene products, wet or dry wipes, geotextiles), or between 100 gsm and 2000gsm in other applications such as carpets, upholstery, or geotextiles.

The needled nonwoven structure may be prepared by any of the following methods:

The entangled nonwoven structures of embodiments of the present invention may be needled and may be produced using industrial-scale needling lines. For example, carding and cross-lapping may be used to mix fibers of any embodiment of the invention (e.g., staple or chopped fibers) and form a block (bat) or mat. Pre-needling may be performed using a plain (plain) barbed needle to form the pad. The nonwoven structure of some embodiments of the present invention may be manufactured by first making a needle punched nonwoven structure as defined above and then subjecting the nonwoven structure to a bonding operation, for example by heat treatment.

comparative testing

Preparation of a needled nonwoven structure:

1. for comparison purposes, PP fibers made from polycim HL10XF polypropylene were used with an MFI of 3.5 g/10 min;

2. The MFI of the PP fibres produced using the embodiments of the invention is 2 g/10 min.

All other properties of all fibres remain the same except for the use of the PP type: the titer was 4.4dtex and the cut length was 90mm, these fibers were uncolored and the same texture and spin finish were used.

Preparation of 120g/m Using each fiber type²weight geotextile needled felt, test 1 is the comparative value and test 2 is the value of the invention.

the carding and needling settings remained the same for all tests.

The properties of the needle-punched felt geotextile were measured by tensile testing:

1. According to ISO 10319

(changing the speed of the grips from the standard value to increasing the test speed (i.e., 50 mm/min.)

2. Repeating at least twice for each type of needled felt

3. each replicate 6 samples MD (machine direction) +6 samples CD (cross direction)

4. Samples were taken and tested in the correct order (i.e., samples 1 and 6 were on the outside of the mat) across the width of the geotextile.

The results are shown in table 1, which shows the improved performance of the nonwoven structures of the present invention.

Applications of the fibers and nonwoven structures of embodiments of the invention:

The fibers and nonwoven structures of embodiments of the present invention may be used in decorative mats (uphosters), for which the mechanical properties are generally most critical. The stronger fibers of embodiments of the present invention result in lower basis weights required for such textiles.

The fibers or nonwoven structures of embodiments of the invention may be used in reinforced building products, such as in the reinforcement of concrete comprising these fibers, where high strength of these fibers is important.

The fibers and nonwoven structures of embodiments of the invention may be used in composite applications, for example, in combination with other fiber types, such as glass fibers, carbon fibers, or natural fibers (wood fibers, flax fibers, hemp fibers).

TABLE 1

Claims

1. A spun drawn fiber comprising a polypropylene composition of a polypropylene homopolymer and having an average MFI of 1 to 5 g/10 min measured according to ISO1133 for polypropylene and a xylene solubles content in the range of 1 to 4.5 wt. -%, or 1.5 to 4.5 wt. -%, having the following properties:

an average elongation of at least 65% as measured according to ISO 5079 at an adjusted test rate of 80 mm/min, and/or

An average toughness/tensile strength of at least 56cN/tex as measured according to ISO 5079 at an 80 mm/min tuned test rate.

2. The spun drawn fiber of claim 1, wherein the polypropylene composition is comprised of one or more polypropylene homopolymers.

3. The spun drawn fiber according to claim 1 or 2, wherein the fiber is a short fiber or a chopped fiber.

4. the spun drawn fiber of any of the preceding claims, wherein the spun drawn fiber has an average MFI of 2 to 4 grams per 10 minutes.

5. Spun drawn fiber of any of the preceding claims, wherein the fiber has a multilobal cross-section.

6. The spun drawn fiber of claim 5, wherein the fiber has a trilobal cross-section.

7. The spun drawn fiber of any of the preceding claims, wherein the fiber is a multicomponent fiber.

8. The spun drawn fiber of claim 7, wherein the fiber is a bicomponent fiber.

9. Spun drawn fiber according to any of the preceding claims, wherein the fiber has a titer of at least 1dtex and at most 100 dtex.

10. The spun drawn fiber according to any of the preceding claims, wherein the polypropylene composition comprises the first polymer and the second polymer as a blend or a multimodal polymer composition.

11. The spun drawn fiber of any of the preceding claims, having an average tenacity/tensile strength of 56 to 70cN/tex and having an elongation at break of 75 to 90%.

12. The spun drawn fiber of any of claims 7 to 11, wherein the polypropylene composition forms the core of a multicomponent fiber.

13. A nonwoven comprising the spun drawn fiber of any of claims 1-12.

14. A geotextile comprising the nonwoven of claim 13.

15. A process for preparing a spun drawn fiber of any of claims 1-12, comprising the steps of:

a) Feeding the polypropylene composition to an extruder;

16. The method of claim 15, wherein the fiber is drawn at a draw ratio of 2 to 4.

17. The method according to claim 15 or 16, wherein the temperature of the polymer in the extruder measured at the extruder outlet and/or the spinning beam is in the range 255 ℃ to 350 ℃, preferably in the range 265 ℃ to 340 ℃, more preferably in the range 275 ℃ to 330 ℃, most preferably in the range 285 ℃ to 320 ℃.

18. A polypropylene composition of a polypropylene homopolymer having an MFI of 1 to 3 g/10 min measured according to ISO1133 and a xylene solubles content of 1 to 4.5 wt.%, or 1.5 to 4.5 wt.%.

19. The polypropylene composition according to claim 18, wherein said xylene solubles content is in the range of 1 to 2 wt. -%, or 1 to 3 wt. -%, or 1 to 3.5 wt. -%, or 1.5 to 3.5 wt. -%, or 1 to 2.5 wt. -%, or 1.5 to 2.5 wt. -%.

20. Polypropylene composition according to claim 18 or 19, wherein the polypropylene composition consists of one or more polypropylene homopolymers.

21. Polypropylene composition according to any one of claims 18 to 20, wherein the polypropylene composition comprises the first polymer and the second polymer as a blend or a multimodal polymer composition.

22. Bicomponent fibers as claimed in claim 8, comprising an outer sheathLeatherAnd a core, wherein the core comprises the polypropylene composition of any one of claims 18 to 21.

23. Bicomponent fibers according to claim 22 having an average tenacity/tensile strength in the range of 56 to 70cN/tex and having an elongation at break of 75 to 90%.