WO2014114638A1 - Fibres d'une composition de polypropylène étirées de haute ténacité présentant des propriétés d'allongement améliorées et non-tissés correspondants - Google Patents

Fibres d'une composition de polypropylène étirées de haute ténacité présentant des propriétés d'allongement améliorées et non-tissés correspondants Download PDF

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Publication number
WO2014114638A1
WO2014114638A1 PCT/EP2014/051133 EP2014051133W WO2014114638A1 WO 2014114638 A1 WO2014114638 A1 WO 2014114638A1 EP 2014051133 W EP2014051133 W EP 2014051133W WO 2014114638 A1 WO2014114638 A1 WO 2014114638A1
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Prior art keywords
polymer
propylene
polypropylene composition
fibers
rubber
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PCT/EP2014/051133
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English (en)
Inventor
Pieter GEEURICKX
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Total Research & Technology Feluy
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Application filed by Total Research & Technology Feluy filed Critical Total Research & Technology Feluy
Priority to EP14701513.5A priority Critical patent/EP2807293A1/fr
Priority to US14/761,976 priority patent/US20150329992A1/en
Publication of WO2014114638A1 publication Critical patent/WO2014114638A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/12—Stretch-spinning methods
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/08—Melt spinning methods
    • D01D5/098—Melt spinning methods with simultaneous stretching
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
    • D01F6/06—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins from polypropylene
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/46—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polyolefins
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/005—Synthetic yarns or filaments
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2321/00—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D10B2321/02—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins
    • D10B2321/022—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins polypropylene
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2401/00—Physical properties
    • D10B2401/06—Load-responsive characteristics
    • D10B2401/063—Load-responsive characteristics high strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
    • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
    • Y10T442/637—Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material

Definitions

  • the invention relates generally to fibers prepared from polypropylene compositions. Particularly it relates to high-tenacity drawn fibers prepared from polypropylene blends, such as blends of polypropylene polymer and heterophasic propylene copolymer. The invention also relates to production process of such high-tenacity drawn fibers. Additionally, it relates to nonwovens comprising such high-tenacity drawn fibers.
  • high-tenacity fibers and nonwoven for use for example in geotextiles or in the automotive industry are one of the applications that have attracted special attention.
  • high-tenacity fibers can be defined as having a tensile strength of at least 45 cN/tex.
  • melt flow index in the range of 3 to 6 dg/min for very strong high-tenacity fibers up to thousand dg/min for meltblown nonwovens.
  • High-tenacity fibers may be produced by melting a polypropylene composition in an extruder and extruding the molten polypropylene through the fine capillaries spinneret to obtain filaments. These filaments are then cooled and thus solidified. In order to increase the tensile strength, the solidified fibers are reheated, drawn at elevated temperature and finally annealed. In general it is observed that the tensile strength of the fibers increases with increasing draw ratio. However, the increase in tensile strength is accompanied by a decrease in elongational properties. This can lead to fibers that have a high tensile strength but because lacking of elongational properties are unable to absorb sufficiently energy and therefore tend to break easily.
  • Producers of high-tenacity fibers and nonwovens are therefore interested in polypropylene compositions that allow reaching high tensile strength without losing in elongational properties.
  • producers of high-tenacity fibers and nonwovens are interested in polypropylene compositions that allow reaching high tensile strength with an improved toughness modulus.
  • inventive drawn fibers are prepared using a polypropylene composition which comprises a heterophasic propylene copolymer, frequently also referred as “impact copolymers” or "propylene block copolymers”.
  • the polypropylene composition is prepared from a polymer blend of a heterophasic propylene copolymer and a propylene homopolymer or of a heterophasic propylene copolymer and a mini random propylene copolymer.
  • the fibers prepared according such polypropylene composition are drawn at a draw ratio of at least 3 to obtain high-tenacity fibers having a tensile strength of at least 45 cN/tex.
  • the drawn fibers according to the invention show improved elongational properties compared to drawn fibers prepared with polypropylene composition without rubber.
  • It is an object of the present invention to provide drawn fibers comprising a polypropylene composition, said polypropylene composition comprising a propylene polymer in a matrix phase and a rubber in a dispersed phase; the propylene polymer comprising propylene and at most 1 wt%, relative to the total weight of said polypropylene composition, of one or more comonomers selected from the group consisting of ethylene and C 4 -Ci 0 alpha-olefins; wherein the polypropylene composition comprises a rubber in an amount from at least 0.2 wt% to at most 7 wt% relative to the total weight of the polypropylene composition.
  • the drawn fibers consist of said polypropylene composition.
  • the propylene polymer which serves as matrix in the polypropylene composition according to the invention is a propylene homopolymer (i.e. with a comonomer content of 0 wt%) or a mini-random copolymer of propylene (i.e. with a comonomer content from 0.05 wt% to 1 wt%, with preference from 0.05 wt% to 0.5 wt%).
  • the C 4 - Cio alpha-olefins are selected from the group consisting of 1 -butene, 1 -pentene, 4-methyl-1 - pentene, 1 -hexene and 1 -octene.
  • the one or more comonomer is ethylene.
  • the propylene polymer which serves as matrix in the polypropylene composition is a propylene homopolymer.
  • said propylene homopolymer has a xylene soluble content in the range from 1 .5 wt% to 4.5 wt% relative to the weight of the propylene homopolymer; preferably in the range from 1 .5 wt% to 3.5 wt%, most preferably in the range from 1 .5 wt% to 2.5 wt%.
  • the rubber consists of a copolymer of ethylene and at least one further olefin different from ethylene.
  • the at least one further olefin is selected from the group C3-C10 alpha-olefins. More preferably it is selected from the group consisting of propylene, 1 -butene, 1 -pentene, 4-methyl-1 -pentene, 1 -hexene and 1 -octene. Even more preferably it is propylene or 1 -butene. Most preferably it is propylene.
  • the most preferred rubber is ethylene propylene rubber (EPR).
  • the rubber has an intrinsic viscosity r ⁇ R of at least 2.0 dl/g, measured in tetralin at 135°C following ISO 1628.
  • the rubber has an intrinsic viscosity r ⁇ R of at least 2.5 dl/g, more preferably of at least 3.0 dl/g, and of at most 5.5 dl/g, preferably of at most 5.0 dl/g and more preferably of at most 4.5 dl/g.
  • the polypropylene composition comprises the rubber in an amount from at least 0.3 wt%, preferably at least 0.4 wt% and most preferably at least 0.5 wt% relative to the total weight of the polypropylene composition.
  • the polypropylene composition comprises the rubber in an amount of at most 6 wt% or 4 wt%, preferably at most 2 wt% and most preferably at most 1 .5 wt% relative to the total weight of the polypropylene composition. In a preferred embodiment, the polypropylene composition comprises the rubber in an amount of less than 2.0 wt% relative to the total weight of the polypropylene composition.
  • the polypropylene composition of the present invention comprises a propylene polymer and a rubber, which when taken together preferably comprise at least 97.0 wt% of the polypropylene composition. More preferably they comprise at least 99.0 wt% or 99.5 wt% and even more preferably at least 99.8 wt% relative to the total weight of the polypropylene composition.
  • the remainder can for example be made up of additives and/or nucleating agents as defined below.
  • the drawn fiber consists of multiple filaments of the polypropylene composition, said filaments having a titer of at least 2 dtex and of at most 100 dtex, preferably of at least 2 dtex and of at most 20 dtex, most preferably of at least 3 dtex and at most 15 dtex.
  • the drawn fibers are characterized by a high tenacity of at least 45 cN/tex.
  • the drawn fibers have a high tenacity of at least 45 cN/tex and a toughness modulus of at least 100 MPa, with preference at least 1 10MPa.
  • the drawn fiber is produced by means of a polymer blend comprising: from 50 to 98 wt% by weight of the polymer blend, of a first polymer which is a propylene polymer comprising propylene and at most 1 %, relative to the total weight of the polymer, of one or more comonomers selected from the group consisting of ethylene and C 4 -Ci 0 alpha-olefins, and
  • the first and second polymers are prepared using a Ziegler-Natta catalyst.
  • the rubber is ethylene propylene rubber (EPR).
  • EPR ethylene propylene rubber
  • the propylene polymer in the second polymer is a propylene homopolymer.
  • the rubber with preference ethylene-propylene rubber (EPR), is present in the polymer blend in an amount from 0,2 to 7 wt%, relative to the total weight of the polymer blend.
  • EPR ethylene-propylene rubber
  • the rubber content, relative to the total weight of the polymer blend is at least 0.3 wt%, preferably at least 0.4 wt%, more preferably at least 0.5 wt%.
  • the rubber content, relative to the total weight of the polymer blend is at most 6 wt% or 4 wt%, preferably at most 2 wt%, more preferably at most 1 .5 wt%.
  • the polymer blend comprises the rubber in an amount of less than 2.0 wt% relative to the total weight of the polymer blend.
  • the rubber is present in an amount from 8 to 18 wt% relative to the total weight of the second polymer (i.e. the heterophasic propylene copolymer), preferably from 10 to 15 wt%.
  • the first polymer is selected from the group consisting of homopolymer polypropylene and random copolymers of propylene and one or more comonomers selected from the group consisting of ethylene and C 4 -Ci 0 alpha-olefin.
  • the propylene polymer is a propylene homopolymer, i.e. with a comonomer content of 0 wt%.
  • the first polymer is a mini random propylene copolymer comprising from 0.05 wt% to 1 wt%, relative to the total weight of said copolymer, of one or more comonomers selected from the group consisting of ethylene and C 4 -Ci 0 alpha-olefins.
  • the first polymer is a propylene hompolymer comprising at least two propylene homopolymer fractions of different melt flow index, wherein the ratio of the melt flow index of the fraction with the highest melt flow index and the melt flow index of the fraction with the lowest melt flow index is in the range from 3 to 400, preferably in the range of 5 to 200, more preferably in the range of 10 to 50 and most preferably in the range of 15 to 30.
  • the first polymer is a propylene homopolymer comprising at least two propylene homopolymer fractions of different melt flow index, wherein the propylene homopolymer fraction with the lowest melt flow index comprises from 55 wt% to 65 wt%, preferably from 55 wt% to 60 wt% of the propylene homopolymer.
  • the first polymer shows by one or more of the following properties:
  • a xylene soluble content in the range from 1 .5 wt% to 4.5 wt%; preferably in the range from 1 .5 wt% to 3.5 wt%, most preferably in the range of 1 .5 wt% to 2.5 wt% and/or
  • melt flow index of at least 3.0 dg/min, more preferably of at least 4.0 dg/min, and most preferably of at least 5.0 dg/min;
  • the first polymer also shows very high isotacticity, for which the content of mmmm pentads is a measure.
  • tacticity is in the range from 97 % to 99 % of mmmm pentads, determined on the insoluble heptane fraction of the xylene insolubles fraction.
  • the fiber is drawn in the solid state at a draw ratio of at least 3 and shows a tensile strength of at least 45 cN/tex.
  • the fiber is drawn at a draw ratio of at least 3 and shows a tensile strength of at least 45 cN/tex and a toughness modulus of at least 100 MPa, preferably of at least 1 10 MPa.
  • the invention discloses nonwovens comprising such fibers.
  • the present invention provides a process for the production of high-tenacity fibers.
  • the fibers are produced according to a compact spinning process (short spin) wherein a polypropylene composition is subjected to a process comprising the step of melt-spinning and drawing at a draw ratio of at least 3 to obtain fibers having a tensile strength of at least 45 cN/tex.
  • a compact spinning process short spin
  • a polypropylene composition is subjected to a process comprising the step of melt-spinning and drawing at a draw ratio of at least 3 to obtain fibers having a tensile strength of at least 45 cN/tex.
  • the fibers are produced according to a traditional spinning process in at least two steps.
  • the process comprises the steps of: a) providing a polypropylene composition to an extruder
  • the polypropylene composition used in the process is the polypropylene according to the invention and described above which comprises a propylene polymer in a matrix phase and a rubber in a disperse phase; the propylene polymer comprising propylene and at most 1 wt%, relative to the total weight of said polypropylene composition, of one or more comonomers selected from the group consisting of ethylene and C 4 -Ci 0 alpha-olefins; wherein the polypropylene composition comprises a rubber in an amount from at least 0.2 wt% to at most 7 wt% relative to the total weight of the polypropylene composition.
  • the polypropylene composition is produced by means of a polymer blend as described above.
  • Fig. 1 provides a graphical representation of a performance ranking of Busschaert-fibers, containing different levels of heterophasic propylene copolymer based on their toughness modulus, which is defined as the integration of the average stress-strain curve relative to the volume of the fiber.
  • the average stress-strain curve is defined as the average stress strain curve of fibers drawn at D/R_max and D/R_max-10%.
  • polypropylene and “propylene polymer” may be used synonymously.
  • % 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 drawn fiber of the invention is preferably produced by means of a polymer blend.
  • the polymer blend according to the invention comprises a propylene polymer and a heterophasic propylene copolymer.
  • the preferred heterophasic propylene copolymer shows a rubber content of 5 to 25 wt% relative to the total weight of the heterophasic propylene copolymer.
  • the preferred blend comprises: from 50 to 98 wt% by weight of the polymer blend, of a first polymer which is a propylene polymer comprising propylene and at most 1 wt%, relative to the total weight of the polymer, of one or more comonomers selected from the group consisting of ethylene and C4-C1 0 alpha-olefins, and
  • a second polymer which is a heterophasic propylene copolymer comprising a propylene polymer and a rubber, with preference the rubber is ethylene propylene rubber (EPR).
  • EPR ethylene propylene rubber
  • the first polymer is a homopolymer polypropylene or a mini-random copolymer of propylene and ethylene or one or more C 4 -Ci 0 alpha-olefin.
  • the preferred random copolymer is a copolymer of propylene and ethylene.
  • the random copolymers of propylene of the invention comprise at least 0.05 wt% and at most 1 wt% of comonomer.
  • the most preferred first polymer is a propylene homopolymer.
  • the second polymer is a heterophasic propylene copolymer.
  • the propylene polymer of the heterophasic propylene copolymer is a propylene homopolymer.
  • the heterophasic propylene copolymer is chosen and provided in an amount sufficient to achieve a rubber content in the polypropylene composition ranging from at least 0.2 to at most 7 %wt relative to the total weight of the polypropylene composition.
  • the polypropylenes used in the present invention are produced by polymerizing propylene and one or more optional comonomers in the presence of a Ziegler-Natta catalyst system or a metallocene catalyst system, which is well-known to the skilled person.
  • a Ziegler-Natta catalyst system comprises a titanium compound having at least one titanium- halogen bond and an internal electron donor, both on a suitable support, an organoaluminium compound, and an optional external donor.
  • a suitable support is for example a magnesium halide in an active form.
  • a suitable external donor (ED) is for example a phtalate or a succinate or a diether compound.
  • the organoaluminium compound used in the process of the present invention is triethyl aluminium (TEAL).
  • TEAL triethyl aluminium
  • the triethyl aluminium has a hydride content, expressed as AIH 3 , of less than 1 .0 wt% with respect to the triethyl aluminium. More preferably, the hydride content is less than 0.5 wt%, and most preferably the hydride content is less than 0.1 wt%.
  • the organoaluminium compound contains minor amounts of other compounds of the trialkylaluminium family, such as triisobutyl aluminium, tri-n-butyl aluminium, and linear or cyclic alkyl aluminium compounds containing two or more Al atoms, provided they show polymerization behavior comparable to that of TEAL.
  • the molar ratio Al/Ti is not particularly specified. However, it is preferred that the molar ratio Al/Ti is at most 100.
  • the molar ratio AI/ED is at most 120, more preferably it is in the range from 5 to 120, and most preferably in the range from 10 to 80.
  • the catalytic system Before being fed to the polymerization reactor the catalytic system preferably undergoes a premix and/or a pre-polymerization step.
  • the premix step the triethyl aluminium (TEAL) and the external electron donor (ED) - if present -, which have been pre-contacted, are mixed with the Ziegler-Natta catalyst at a temperature in the range from 0°C to 30°C, preferably in the range from 5°C to 20°C, for up to 15 min.
  • the mixture of TEAL, external electron donor (if present) and Ziegler-Natta catalyst is pre-polymerized with propylene at a temperature in the range from 10°C to 100°C, preferably in the range from 10°C to 30°C, for 1 to 30 min, preferably for 2 to 20 min.
  • the metallocene catalysts are compounds of Group IV transition metals of the Periodic Table such as titanium, zirconium, hafnium, etc., and have a coordinated structure with a metal compound and ligands composed of one or two groups of cyclopentadienyl, indenyl, fluorenyl or their derivatives. Use of metallocene catalysts in the polymerization of olefins has various advantages.
  • Metallocene catalysts have high activities and are capable of preparing polymers with enhanced physical properties in comparison with the polymers prepared using Ziegler-Natta catalysts.
  • the key to metallocenes is the structure of the complex.
  • the structure and geometry of the metallocene can be varied to adapt to the specific need of the producer depending on the desired polymer.
  • Metallocenes comprise a single metal site, which allows for more control of branching and molecular weight distribution of the polymer. Monomers are inserted between the metal and the growing chain of polymer.
  • the metallocene catalysts generally are provided on a solid support.
  • the support should be an inert solid, which is chemically unreactive with any of the components of the conventional metallocene catalyst.
  • the support is preferably a silica compound.
  • the polymerization propylene and one or more optional comonomers can for example be carried out in liquid propylene as reaction medium (bulk polymerization). It can also be carried out in diluents, such as hydrocarbon that is inert under polymerization condition (slurry polymerization). It can also be carried out in the gas phase. Those processes are well known to one skilled in the art.
  • Diluents which are suitable for being used in accordance with the present invention may comprise but are not limited to hydrocarbon diluents such as aliphatic, cycloaliphatic and aromatic hydrocarbon solvents, or halogenated versions of such solvents.
  • Nonlimiting illustrative examples of solvents are butane, isobutane, pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane, methyl cyclopentane, methyl cyclohexane, isooctane, benzene, toluene, xylene, chloroform, chlorobenzenes, tetrachloroethylene, dichloroethane and trichloroethane.
  • the propylene polymers are preferably produced by polymerization in liquid 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 25 and 50 bar.
  • Hydrogen is used to control the chain lengths of the propylene polymers.
  • concentration of hydrogen in the polymerization medium needs to be increased.
  • the hydrogen concentration in the polymerization medium has to be reduced in order to produce a propylene polymer with lower MFI, i.e. with higher average molecular weight and longer polymer chains.
  • propylene homopolymer is marketed as Polypropylene PPH 5069 by Total.
  • Such propylene homopolymer has a typical melt flow index of 6 g/10min.
  • the first polymer comprises at least two propylene homopolymer fractions of different melt flow index, wherein the ratio of the melt flow index of the fraction with the highest melt flow index and the melt flow index of the fraction with the lowest melt flow index is in the range from 3 to 400.
  • Such bimodal propylene homopolymer is preferably produced in a polymerization unit having two loop reactors in series.
  • the propylene homopolymer withdrawn from one reactor is transferred to the one following in the series, where the polymerization is continued.
  • the polymerization conditions in the respective polymerization reactors need to be different, for example in that the hydrogen concentration in the polymerization reactors differs.
  • the first propylene polymer is recovered as a powder and can then be pelletized or granulated.
  • heterophasic propylene copolymers according to the invention comprise a matrix propylene polymer phase and a dispersed phase of a rubber, by preference ethylene propylene rubber (EPR).
  • EPR ethylene propylene rubber
  • the heterophasic propylene copolymer of the present invention as defined above is produced by sequential polymerization in a series of polymerization reactors in presence of a catalyst system, wherein in a first polymerization stage the propylene polymer is produced, and in a second polymerization stage the rubber is produced by copolymerizing ethylene and at least one further olefin that is different from ethylene.
  • the further olefin is polypropylene.
  • the rubber produced is EPR.
  • the matrix propylene polymer phase is a preferably propylene homopolymer.
  • the polymerization is conducted to obtain a rubber content from 5 to 25 wt% relative to the total weight of the heterophasic propylene copolymer, preferably from 8 to 18 wt%, more preferably from 10 to 15 %.
  • catalysts systems used for the production of such copolymers are Ziegler-Natta catalyst systems, as described above for the preparation of the first polymer.
  • the catalyst system is added to the first polymerization stage.
  • the propylene copolymer can be prepared using a controlled morphology catalyst that produces rubber spherical domains dispersed in a polypropylene matrix. The amount and properties of the components are controlled by the process conditions.
  • the matrix propylene polymer preferably propylene homopolymer
  • the matrix propylene polymer can be made for example in loop reactors or in a gas phase reactor.
  • the propylene polymer produced in this way, in a first polymerization stage, is transferred to a second polymerization stage, into one or more secondary reactors where ethylene and propylene monomer is added to produce the EPR.
  • this polymerization step is done in a gas phase reactor.
  • the average molecular weight of the rubber, for which the intrinsic viscosity r ⁇ R is a measure, is controlled by addition of hydrogen to the polymerization reactors of the second polymerization stage.
  • the amount of hydrogen added is such that the rubber as a intrinsic viscosity of at least 2.0 dl/g, measured in tetralin at 135°C following ISO 1628.
  • the contribution of the second polymerization stage i.e. the rubber content of the heterophasic propylene copolymer is from 5 to 25 wt% relative to the total weight of the heterophasic propylene copolymer.
  • heterophasic propylene copolymer An example of suitable commercially available heterophasic propylene copolymer is marketed as Polypropylene PPC 5660 by Total. Such heterophasic propylene copolymer has a typical melt flow index of 7 g/10min.
  • the second polymer is recovered as a powder and can then be pelletized or granulated.
  • the first and/or second propylene polymers and/or the polypropylene composition according to the invention may contain additives such as, by way of example, antioxidants, light stabilizers, acid scavengers, flame retardants, lubricants, antistatic additives, nucleating/clarifying agents, colorants.
  • additives such as, by way of example, antioxidants, light stabilizers, acid scavengers, flame retardants, lubricants, antistatic additives, nucleating/clarifying agents, colorants.
  • the antioxidants used in the propylene polymers of the present invention preferably have anti-gas fading properties.
  • the preferred antioxidants are selected from the group consisting of phosphites, hindered phenols, hindered amine stabilizers and hydroxylamines.
  • An example for a suitable antioxidant additivation is a blend of Irgafos 168 and Irganox 31 14.
  • phenol-free antioxidant additivations are suitable as well, such as for example those based on hindered amine stabilizers, phosphites, hydroxylamines or any combination of these.
  • the antioxidants are added to the propylene homopolymer in an amount from 100 ppm to 2000 ppm with the exact amount depending upon the nature of the antioxidant, the processing conditions and other factors.
  • the first polymer i.e. the propylene homopolymer and/or the random propylene copolymer
  • the second polymer i.e. the heterophasic propylene polymer
  • the amount of heterophasic propylene polymer used with the homopolymer and/or the random propylene copolymer, is calculated in order to have the desired amount of rubber in the polypropylene composition of the fiber.
  • the desired amount of rubber ranges from 0.2 wt% to 7 wt% relative to the total weight of the polypropylene composition of the fiber.
  • a suitable blend according to the invention is a blend comprising from 50 to 98 wt% of a propylene homopolymer and from 2 to 50 wt% of an heterophasic propylene copolymer, relative to the total weight of the polymer blend.
  • the blend comprises from 2 to 20 wt%, more preferably from 3 to 15 wt% of the heterophasic propylene copolymer relative to the total weight of the polymer blend, even more preferably from 5 to 10 wt%.
  • the propylene homopolymer and the heterophasic propylene copolymer are mixed together in pelletized, fluff or powder form prior to being introduced into an extruder.
  • the polymers may be dry blended together prior to being introduced into the extruder.
  • the polymers may be introduced separately into the extruder at a position to achieve thorough mixing of the polymers within the extruder, such as with a gravimetric or volumetric dosing unit, which are commonly known in the art.
  • the first polymer i.e. the propylene homopolymer and/or the random propylene copolymer
  • the second polymer i.e. the heterophasic propylene polymer
  • the resulting polypropylene composition has a melt flow index of at least 3.0 g / 10 min, more preferably of at least 4.0 g / 10 min, and most preferably of at least 5.0 g / 10 min and/or a melt flow index of at most 15 g / 10 min, preferably at most 12 g / 10 min, more preferably a at most 15 g / 10 min, the melt flow index being measured according to ISO 1 133.
  • Additives may be combined with the polymers during the extrusion process, such as, by way of example, antioxidants, light stabilizers, acid scavengers, flame retardants, lubricants, antistatic additives, nucleating/clarifying agents, colorants.
  • antioxidants light stabilizers
  • acid scavengers acid scavengers
  • flame retardants flame retardants
  • lubricants antistatic additives
  • nucleating/clarifying agents colorants.
  • An overview of such additives may be found in Plastics Additives Handbook, ed. H. Zweifel, 5 th edition, 2001 , Hanser Publishers. PROCESS FOR PRODUCTION OF HIGH TENACITY DRAWN FIBERS
  • the polypropylene composition of the present invention is used to produce fibers and yarns. In particular, it is used to produce staple fibers and high-tenacity yarns. These may in turn be used in the manufacture of nonwovens.
  • the methods used in the production of the fibers and yarns as well as the nonwovens are known to the person skilled in the art and are for example described in Polypropylene Handbook, ed. Nello Pasquini, 2nd edition, Hanser, 2005, pages 397-403.
  • the polypropylene composition resulting from the blend of the first and second polymer is then extruded through a number of fine capillaries of a spinneret, thus obtaining molten fibers.
  • the still molten fibers (also called “filaments”) are simultaneously cooled by air and melt drawn to an intermediate diameter. Subsequently they are solidified. Preferably, the solidified fibers are re-heated to a temperature of 150°C or less, drawn to a draw ratio of at least 3, and then annealed. In a preferred mode the annealed fibers are cut to a length in the range from 1 .5 mm to 200 mm, preferably in the range from 10 mm to 100 mm. Such "cut fibers" are generally referred to as "staple fibers".
  • Staple fibers in general are produced either by the traditional spinning process or the compact spinning process.
  • staple fibers are produced in two steps.
  • the first step includes fiber production, application of a spin finish to give certain desired properties to the fibers, and winding the undrawn fiber bundle or tow.
  • the second step includes drawing of the fibers, optional application of a second spin finish, optional crimping or texturizing and cutting into staple fibers.
  • the compact spinning, also called short spin, process is a one-step process, wherein fiber extrusion, drawing, and optional crimping or texturizing are performed in a single step.
  • the staple fibers produced in accordance with the present invention may subsequently be used to produce nonwovens.
  • the production of nonwovens comprises the steps of carding, thus forming a web, which is then passed through a bonding step. Bonding of the web can be accomplished by thermobonding, hydroentanglement, needle punching, or chemical bonding. For geotextiles and nonwovens for automotive applications needle punching is preferred.
  • the nonwovens of the present invention are preferably geotextiles and nonwovens for automotive applications.
  • the fibers and yarns produced in accordance with the present invention have a high tenacity and an improved toughness modulus with respect to the prior art fibers and yarns.
  • the fibers and yarns produced in accordance with the present invention have a high tenacity of at least 45 cN/tex and a toughness modulus of at least 100 MPa. They also show improved elongational properties.
  • the fibers and yarns of the present invention show an improved tensile strength in combination with improved elongational properties.
  • the fibers and yarns of the present invention are characterized by tensile strength of 45 cN/tex or higher, in order to be well suited for nonwovens.
  • the melt flow index was measured according to ISO 1 133, condition L, using a weight of 2.16 kg and a temperature of 230 °C.
  • Xylene solubles were determined as follows: Between 4.5 and 5.5 g of propylene polymer were weighed into a flask and 300 ml xylene were added. The xylene was heated under stirring to reflux for 45 minutes. Stirring was continued for 15 minutes exactly without heating. The flask was then placed in a thermostated bath set to 25°C +/- 1 °C for 1 hour. The solution was filtered through Whatman n° 4 filter paper and exactly 100 ml of solvent were collected. The solvent was then evaporated and the residue dried and weighed. The percentage of xylene solubles ("XS”) was then calculated according to
  • XS (in wt%) (Weight of the residue / Initial total weight of PP) * 300 with all weights being in the same units, such as for example in grams.
  • Acetone insolubles are determined as follow: 100 ml of the filtrate of the solution in xylene (see above) and 700 ml of acetone are agitated overnight at room temperature in a hermetically sealed flask, during which time a precipitate is formed. The precipitate is collected on a metal mesh filter with a mesh width of 0.056 mm, dried and weighed. The percentage of acetone insolubles ("Aclns") is then calculated according to :
  • Aclns (in wt%) (Weight of the residue / initial weight of PP) * 300 with all weights being in the same units, such as for example in grams.
  • the amount of rubber in heterophasic propylene copolymer or in the polymer resulting from the polymer blend, is determined as the acetone insoluble fraction of the xylene soluble fraction.
  • the intrinsic viscosity of the rubber is determined using the acetone insoluble fraction of the xylene soluble fraction of the heterophasic propylene copolymer.
  • the intrinsic viscosity is determined in a capillary viscometer in tetralin at 135 °C.
  • the polydispersity index (PDI) is determined using the ratio of the weight average molecular weight of the polymer to the number average molecular weight of the polymer (Mw/Mn).
  • Mw is determined by gel permeation chromatography (GPC) at 145°C in 1 ,2,4-trichlorobenzene. The resulting solution is injected into a gel permeation chromatograph and analyzed under conditions well-known in the polymer industry.
  • Heptane insolubles were isolated as follows: The xylene insoluble fraction (see above) was dried in air for a minimum of 3 days and manually ground into small pieces, of which ca. 2 g are weighed into the extraction thimble of a Soxleth extractor and extracted with heptane under reflux for 15 hours. The heptane insoluble fraction is recovered from the thimble, and dried in air for a minimum of 4 days.
  • G c is the cross-over modulus in Pascal determined at 230°C using a dynamic rheometer in frequency sweep with a strain of 20% on an ARES from Tainstrument, branch of WATERS.
  • the isotacticity (mmmm %) is determined by NMR analysis according to the method described by G.J. Ray et al. in Macromolecules, vol. 10, n° 4, 1977, p. 773-778. It is performed on the dried product resulting of the extraction by boiling heptane of the xylene insoluble PP fraction.
  • the recovery compliance is determined at a temperature of 210°C using a parallel-plate rotational stress rheometer.
  • the sample is contained between two coaxial parallel discs in an oven filled with nitrogen.
  • the test consists of monitoring the strain response when the stress has been deleted after a creep test. For the creep test a stress of 600 Pa is applied. Then the recovery compliance is the recoverable strain divided by the stress applied during the creep.
  • Filaments titers were measured on a Zweigle vibroscope S151/2 in accordance with norm ISO 1973:1995.
  • For Busschaert fibres tensile strength and elongation were measured on a Textechno Statimat ME according to norm ISO 2062-B (250mm length with a testing speed of 250 mm/min).
  • the toughness modulus is defined as the integration of the average stress-strain curve of a set of tested fibers till break.
  • the polypropylene composition of the fiber is obtained in blending two polymers. Their properties are given in table 1.
  • Examples 2, 3 and 4 in accordance with the invention show a rubber content in the range from 0.2 to 7 wt% by weight of the polypropylene composition.
  • Examples 1 and 5 are comparative examples.
  • the propylene polymers were spun into fibers on a Busschaert fiber spinning pilot line equipped with two dies of 1 12 circular holes each of a diameter of 0,3 mm and an L/D ratio of 3,2.
  • the melt temperature was kept at 280°C.
  • the filaments were drawn between two pairs of godets with the temperature of the first pair being at 80°C and the second pair being at 90°C.
  • Draw ratio was between 3 and 5.
  • the targeted fiber titer was in the range from 5 to 7 dtex per filament. This was achieved by keeping the winder speed after the drawing step at constant speed of 1200 m/min and adapting the take-up speed, i.e. the speed at which the fibers are collected directly after melt spinning. It is noted that long spin fibres (multifilament), produced on the Busschaert fiber spinning pilot line, typically reach 40 - 60 cN/Tex at 20 - 60% elongation at break.
  • the fibers show a tensile strength of at least 45 cN/tex. Their tensile strength are improved relative to the comparative example 5. Their elongational properties are improved relative to the comparative example 1 .
  • the toughness modulus of the fibers is improved for the fibers of the invention relative to the comparative examples.
  • results further show that for a polypropylene composition comprising a rubber content in the range from at least 0.2 wt% to less than 6.0 wt% relative to the total weight of the polypropylene composition, preferably to less than 2.0 wt%, a tensile strength of at least 45 cN/tex can be obtained with a draw ratio lower than in the comparative examples.
  • the drawn fibers according to the invention show higher tensile strength and improved elongational properties at a lower draw ratio compared to drawn fibers prepared with higher content of rubber.
  • the targeted tensile strength of at least 45 cN/tex in combination with a toughness modulus of at least 100 MPa results from the properties of the polypropylene composition combined with the described production process of the fibers in which the fibers are drawn in a solid state.
  • Fig. 1 provides a graphical representation of a performance ranking of Busschaert-fibers, containing different levels of a heterophasic propylene copolymer (% of copo in blend), based on their toughness modulus (in Mpa), which is defined as the integration of the average stress-strain curve relative to the volume of the fiber.
  • the average stress-strain curve is defined as the average stress-strain curve of fibers drawn at D/R_max and D/R_max-10%.
  • D/R_max is determined as the D/R that still allows spinning a small bobbin before a fibre break occurs.
  • the curve demonstrates that a significant improvement can be achieved by blending about 2 to 50 wt%, preferably 2 to 20 wt%, and most preferably about 3 to 15 wt% of the heterophasic propylene copolymer into a polypropylene homopolymer, with the EPR content in the heterophasic propylene copolymer being 13 wt% relative to the heterophasic propylene copolymer weight.
  • the high-tenacity fibers of the present invention show the desired combination of tensile strength and elongational properties.

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  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
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Abstract

La présente invention porte sur des fibres de haute ténacité présentant des propriétés d'allongement améliorées, particulièrement appropriées pour des non-tissés tels que des géotextiles, constituées de compositions de polypropylène comprenant de 0,2 % en poids à 7 % en poids d'un caoutchouc dans une phase dispersée. Les fibres ont une résistance à la traction, mesurée conformément à la norme ISO 2062-B, d'au moins 45 cN/tex. La présente invention porte en outre sur un procédé pour la production de telles fibres.
PCT/EP2014/051133 2013-01-22 2014-01-21 Fibres d'une composition de polypropylène étirées de haute ténacité présentant des propriétés d'allongement améliorées et non-tissés correspondants WO2014114638A1 (fr)

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US14/761,976 US20150329992A1 (en) 2013-01-22 2014-01-21 High-Tenacity Drawn Fibers of a Polypropylene Composition with Improved Elongational Properties and Nonwovens

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WO2018167304A1 (fr) 2017-03-17 2018-09-20 Beaulieu International Group Nv Composition de polypropylène dotée de propriétés de traction améliorées, fibres et structures non tissées

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WO2018167304A1 (fr) 2017-03-17 2018-09-20 Beaulieu International Group Nv Composition de polypropylène dotée de propriétés de traction améliorées, fibres et structures non tissées

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