Fiber reinforced thermoplastic polymer composition

Abstract

The present invention relates to a fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand comprising a core extending in a machine direction and a polymeric sheath closely surrounding the core wherein the core comprises at least one continuous multifilament strand, the continuous multifilament strand comprises a plurality of coated filaments in a bundle wherein each of the coated filaments is a coated filament comprising an inorganic filament and a first polymer composition comprising a first thermoplastic polymer, preferably wherein the inorganic filament is a glass filament, wherein the first polymer composition is in direct contact with the filaments, and wherein the polymer sheath consists of a second thermoplastic polymer composition comprising a second thermoplastic polymer.

Description

TECHNICAL FIELD

[0001] The present invention relates to a fiber-reinforced thermoplastic polymer composition and a method for producing such a composition. The present invention further relates to a molded article made of such a composition. BACKGROUND ART

[0002] A glass fiber-reinforced thermoplastic polymer composition can be made by a method comprising the steps of unwinding a continuous glass multifilament strand from a package and applying a sheath of polypropylene around the multifilament strand to form a sheathed continuous multifilament strand.

[0003] Such a method is known from international application WO2009 / 080281. The published patent application discloses a method for producing a long glass fiber-reinforced thermoplastic polymer composition, the method comprising the steps of: i) unwinding at least one continuous glass multifilament strand from a package, ii) applying an impregnating agent to the at least one continuous glass multifilament strand to form an impregnated continuous multifilament strand, and iii) applying a sheath of a thermoplastic polymer around the impregnated continuous multifilament strand to form a sheathed continuous multifilament strand.

[0004] WO2014 / 053590, WO2016 / 062569 and WO2015 / 032699 disclose pellets of a fiber-reinforced polymer composition comprising a core and a thermoplastic polymer sheath surrounding the core, wherein the core comprises glass fibers extending in the longitudinal direction of the pellet and an impregnating agent.

[0005] It is desirable that a molded article made of a fiber-reinforced thermoplastic polymer composition has good mechanical properties, such as flexural and tensile properties. It is also desirable that the article releases fewer volatile compounds. A good visual appearance is also desirable, for example an appearance with fewer white spots. White spots may occur due to insufficient dispersion of the fibers in the article. Good adhesion to glue and foam is also desirable. SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to provide a fiber-reinforced thermoplastic polymer composition in which the above and / or other requirements are met.

[0007] Accordingly, the present invention provides a fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand, said sheathed continuous multifilament strand comprising a core extending in the longitudinal direction and a polymer sheath tightly surrounding the core,

[0008] wherein the core comprises at least one continuous multifilament strand, said continuous multifilament strand comprising a plurality of coated filaments bundled together,

[0009] wherein each of the coated filaments is a coated filament comprising an inorganic filament and a first polymer composition comprising a first thermoplastic polymer,

[0010] Preferably, the inorganic filaments are glass filaments.

[0011] The first polymer composition is in direct contact with the filaments.

[0012] The polymer sheath consists of a second thermoplastic polymer composition comprising a second thermoplastic polymer.

[0013] The present invention also provides a method for producing a fiber-reinforced thermoplastic polymer composition according to the present invention, wherein a sheathed continuous multifilament strand is prepared by the following sequential steps:

[0014] a) unwinding at least one continuous multifilament strand from a package,

[0015] b) optionally applying an impregnating agent to at least one continuous multifilament strand, and

[0016] c) applying a sheath of a thermoplastic polymer composition around the (impregnated) continuous multifilament strand to form a sheathed continuous multifilament strand.

[0017] Details regarding steps a)-c) are described in WO2009 / 080281A1, which is hereby incorporated by reference.

[0018] The method for producing a fiber-reinforced thermoplastic polymer composition according to the present invention may further comprise the following steps

[0019] d) cutting the sheathed continuous multifilament strand into pellets.

[0020] Surprisingly, it has been found that molded articles made using the fiber-reinforced thermoplastic polymer composition according to the present invention have good mechanical properties. Such articles can release fewer volatile compounds. Such articles can also have a good visual appearance and good adhesion to glue and foam.

[0021] Sheathed continuous multifilament strands

[0022] The fiber-reinforced thermoplastic polymer composition according to the present invention can be in the form of pellets and comprises or consists of sheathed continuous multifilament strands. The sheathed continuous multifilament strands comprise or consist of a core and a polymer sheath. The core has a generally cylindrical shape and comprises at least one continuous multifilament strand. The core can consist of at least one continuous multifilament strand. The core can consist of at least one impregnated continuous multifilament strand, which comprises at least one continuous multifilament strand impregnated with an impregnating agent. At least one continuous multifilament strand comprises or consists of a bundle of a plurality of coated filaments. The core is tightly surrounded around its circumference by a polymer sheath which is generally tubular and consists of a second thermoplastic polymer composition. The inorganic filaments have a length approximately equal to the axial length of the pellets.

[0023] The core is substantially free of sheath material. The sheath is substantially free of inorganic filaments. Such a pellet structure can be obtained by a wire coating method as disclosed in, for example, WO2009 / 080281, and is different from pellet structures obtained by methods of the typical pultrusion type as disclosed in, for example, US6,291,064.

[0024] Preferably, the polymer sheath is substantially free of inorganic filaments, meaning it contains less than 2 wt% inorganic filaments based on the total weight of the polymer sheath.

[0025] Preferably, the core has a radius of 800 - 4000 microns, and / or the polymer sheath has a thickness of 500 - 1500 microns.

[0026] In some embodiments, the core occupies 3 - 35% of the cross - sectional area of the pellet and the sheath occupies 65 - 97% of the cross - sectional area of the pellet. In some embodiments, the core occupies 35 - 60% of the cross - sectional area of the pellet and the sheath occupies 40 - 65% of the cross - sectional area of the pellet.

[0027] Preferably, the amount of the (impregnated) continuous multifilament strands is 10 to 80 wt%, for example 10 to 50 wt% (such as 25 to 45 wt%) or 50 to 80 wt% (such as 60 to 75 wt%) relative to the sheathed continuous multifilament strands. Preferably, the amount of the second thermoplastic composition is 20 to 90 wt%, for example 20 to 50 wt% (such as 25 to 40 wt%) or 50 to 90 wt% (such as 55 to 75 wt%) relative to the sheathed continuous multifilament strands. Preferably, the total amount of the (impregnated) continuous multifilament strands and the second thermoplastic composition is 100 wt% relative to the sheathed continuous multifilament strands.

[0028] Polymer sheath

[0029] The sheath closely surrounds the core. The term "closely surrounds" as used herein should be understood to mean that the polymer sheath substantially completely contacts the core. In other words, the sheath is applied to the core in such a way that there is no intentional gap between the inner surface of the sheath and the core containing the impregnated continuous multifilament strands. Nevertheless, those skilled in the art will understand that some small gaps may be formed between the polymer sheath and the core due to variations in the method.

[0030] The polymer sheath consists of a second thermoplastic polymer composition.

[0031] Thermoplastic polymer composition of the polymer sheath

[0032] The second thermoplastic polymer composition contains a second thermoplastic polymer. Preferably, the second thermoplastic polymer composition consists of the second thermoplastic polymer and any additives as described below.

[0033] Thermoplastic polymer in the thermoplastic polymer composition of the polymer sheath

[0034] The amount of the second thermoplastic polymer may be at least 50% by weight, such as 50 to 99.9% by weight, 75 to 99.9% by weight, or 95 to 99% by weight, based on the second thermoplastic polymer composition.

[0035] Suitable examples of the second thermoplastic polymer include, but are not limited to, polyamides such as polyamide 6, polyamide 66, or polyamide 46; polyolefins such as polypropylene and polyethylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate; polycarbonate; polyphenylene sulfide; polyurethane; and mixtures thereof.

[0036] The second thermoplastic polymer is preferably a polyolefin, more preferably a polyolefin selected from polypropylene or an elastomer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms, and any mixture thereof.

[0037] In one embodiment, preferably the second thermoplastic polymer composition comprises at least 80% by weight of the second thermoplastic polymer, such as at least 90% by weight, at least 93% by weight, at least 95% by weight, at least 97% by weight, at least 98% by weight, or at least 99% by weight, based on the second thermoplastic polymer composition. In a particular embodiment, the second thermoplastic polymer composition consists of the second thermoplastic polymer. In another embodiment, the second thermoplastic polymer composition comprises at least 60% by weight, such as at least 70% by weight, such as at least 75% by weight, and / or at most 99% by weight, such as at most 95% by weight, such as at most 90% by weight, of the second thermoplastic polymer.

[0038] Preferably, the second thermoplastic polymer has a melt flow index measured according to ISO 1133-1:2011 (2.16 kg / 230 °C) in the range of 20 to 150 dg / min, such as in the range of 30 to 140 dg / min. Preferably, the second thermoplastic polymer has a melt flow index measured according to ISO 1133-1:2011 (2.16 kg / 230 °C) in the range of 50 to 130 dg / min.

[0039] The polypropylene can be, for example, a propylene homopolymer or a random propylene copolymer or a multiphase propylene copolymer.

[0040] An isotactic polypropylene homopolymer can be obtained by polymerizing propylene under suitable polymerization conditions. An isotactic polypropylene copolymer can be obtained by copolymerizing propylene with one or more other α-olefins, preferably ethylene, under suitable polymerization conditions. The preparation of isotactic polypropylene homopolymers and copolymers is described, for example, in Moore, E.P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.

[0041] The atactic polypropylene copolymer may contain ethylene or an α-olefin as a comonomer, said α-olefin being selected from α-olefins having 4 to 10 C-atoms, preferably ethylene, 1-butene, 1-hexene or any mixture thereof. The amount of comonomer is preferably at most 10% by weight, based on the atactic polypropylene copolymer, for example in the range of 2 to 7% by weight, based on the atactic polypropylene copolymer.

[0042] Polypropylene can be produced by any known polymerization technique and using any known polymerization catalyst system. Regarding the technique, slurry, solution or gas phase polymerization can be mentioned; regarding the catalyst system, Ziegler-Natta, metallocene or single-site catalyst systems can be mentioned. All are known per se in the art.

[0043] The heterophasic polypropylene copolymer is generally prepared in one or more reactors by polymerizing propylene in the presence of a catalyst and subsequently polymerizing an ethylene-α-olefin mixture. The resulting polymeric material is heterophasic, but the specific morphology generally depends on the preparation method and the monomer ratio used.

[0044] The heterophasic polypropylene copolymer can be produced using any conventional technique known to the person skilled in the art, such as multistage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combination thereof. Any conventional catalyst system can be used, such as Ziegler-Natta or metallocene. Such techniques and catalysts are described, for example, in WO06 / 010414; Polypropylene and other Polyolefins, Ser van der Ven, Studies in Polymer Science 7, Elsevier 1990; WO06 / 010414, US4399054 and US4472524.

[0045] Preferably, the heterophasic polypropylene copolymer is made using a Ziegler-Natta catalyst.

[0046] A multiphase propylene copolymer can be prepared by a process comprising the following steps:

[0047] - polymerizing propylene and optionally ethylene and / or an α-olefin in the presence of a catalyst system to obtain a propylene-based matrix, and

[0048] - subsequently polymerizing ethylene and an α-olefin in the propylene-based matrix in the presence of a catalyst system to obtain a dispersed ethylene-α-olefin copolymer. These steps are preferably carried out in different reactors. The catalyst systems for the first and second steps can be different or the same.

[0049] The multiphase propylene copolymer comprises a propylene-based matrix and a dispersed ethylene-α-olefin copolymer. The propylene-based matrix typically forms the continuous phase in the multiphase propylene copolymer. The amounts of the propylene-based matrix and the dispersed ethylene-α-olefin copolymer can be determined by 13 C-NMR measurement, as is well known in the art.

[0050] The propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer, said propylene copolymer consisting of at least 70% by weight of propylene monomer units and at most 30% by weight of comonomer units selected from ethylene monomer units and α-olefin monomer units having 4-10 carbon atoms, for example consisting of at least 80% by weight of propylene monomer units and at most 20% by weight of comonomer units, consisting of at least 90% by weight of propylene monomer units and at most 10% by weight of comonomer units, or consisting of at least 95% by weight of propylene monomer units and at most 5% by weight of comonomer units, based on the total weight of the propylene-based matrix.

[0051] Preferably, the comonomer in the propylene copolymer of the propylene-based matrix is selected from ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene, and is preferably ethylene.

[0052] Preferably, the propylene-based matrix consists of a propylene homopolymer.

[0053] The melt flow index (MFI) of the propylene-based matrix (before incorporating the multiphase propylene copolymer into the composition of the present invention) (MFI PP ) can be, for example, at least 0.1 dg / min, at least 0.2 dg / min, at least 0.3 dg / min, at least 0.5 dg / min, at least 1 dg / min, at least 1.5 dg / min, and / or for example at most 50 dg / min, at most 40 dg / min, at most 30 dg / min, at most 25 dg / min, at most 20 dg / min, measured according to ISO1133 (2.16 kg / 230 °C). MFI PPIt can be in the range of, for example, 0.1 to 50 dg / min, such as 0.2 to 40 dg / min, such as 0.3 to 30 dg / min, such as 0.5 to 25 dg / min, such as 1 to 20 dg / min, such as 1.5 to 10 dg / min, measured according to ISO1133 (2.16 kg / 230 °C).

[0054] The propylene-based matrix can be present, for example, in an amount of 50 to 95% by weight. Preferably, the propylene-based matrix is present in an amount of 60 to 85% by weight, such as at least 65% by weight or at least 70% by weight and / or at most 78% by weight, based on the total multiphase propylene copolymer.

[0055] The propylene-based matrix is preferably semi-crystalline, i.e., it is not 100% amorphous nor 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, such as at least 50%, such as at least 60% crystalline and / or such as at most 80% crystalline, such as at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. For the purposes of the present invention, the crystallinity of the propylene-based matrix is measured by differential scanning calorimetry (DSC) according to ISO11357-1 and ISO11357-3 of 1997, using a scanning rate of 10 °C / min, a sample of 5 mg, and the second heating curve using 207.1 J / g as the theoretical standard for 100% crystalline material.

[0056] In addition to the propylene-based matrix, the multiphase propylene copolymer further comprises a dispersed ethylene-α-olefin copolymer. The dispersed ethylene-α-olefin copolymer is also referred to herein as the "dispersed phase". The dispersed phase is embedded in the multiphase propylene copolymer in a discontinuous form. The particle size of the dispersed phase is typically in the range of 0.05 to 2.0 microns, as determined by transmission electron microscopy (TEM). The amount of the dispersed ethylene-α-olefin copolymer in the multiphase propylene copolymer can sometimes be referred to herein as RC.

[0057] The amount of ethylene monomer units in the ethylene-α-olefin copolymer can be 20 to 65% by weight. The amount of ethylene monomer units in the dispersed ethylene-α-olefin copolymer in the multiphase propylene copolymer can sometimes be referred to herein as RCC2.

[0058] The α-olefin in the ethylene-α-olefin copolymer is preferably selected from the group of α-olefins having 3 to 8 carbon atoms. Examples of suitable α-olefins having 3 to 8 carbon atoms include, but are not limited to, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. More preferably, the α-olefin in the ethylene-α-olefin copolymer is selected from the group of α-olefins having 3 to 4 carbon atoms and any mixtures thereof, and more preferably the α-olefin is propylene, in which case the ethylene-α-olefin copolymer is an ethylene-propylene copolymer.

[0059] The MFI (before mixing the multiphase propylene copolymer into the composition of the present invention) (MFI rubber) of the dispersed ethylene α-olefin copolymer can be, for example, at least 0.001 dg / min, at least 0.01 dg / min, at least 0.1 dg / min, at least 0.3 dg / min, at least 0.7 dg / min, at least 1 dg / min, and / or, for example, at most 30 dg / min, at most 20 dg / min, at most 15 dg / min, at most 10 dg / min, at most 5 dg / min, or at most 3 dg / min. The MFI rubber can be in the range of, for example, 0.001 to 30 dg / min, for example, 0.01 to 20 dg / min, for example, 0.1 to 15 dg / min, for example, 0.3 to 10 dg / min, for example, 0.7 to 5 dg / min, for example, 1 to 3 dg / min. The MFI rubber is calculated according to the following formula:

[0060]

[0061] wherein,

[0062] MFI multiphase is the MFI (dg / min) of the multiphase propylene copolymer measured according to ISO1133 (2.16 kg / 230 °C),

[0063] MFI matrix is the MFI (dg / min) of the propylene-based matrix measured according to ISO1133 (2.16 kg / 230 °C),

[0064] Matrix content is the fraction of the propylene-based matrix in the multiphase propylene copolymer,

[0065] Rubber content is the fraction of the dispersed ethylene-α-olefin copolymer in the multiphase propylene copolymer. The sum of the matrix content and the rubber content is 1. To avoid any doubt, Log in the formula means log 10 .

[0066] The dispersed ethylene-α-olefin copolymer is present in an amount of 50 to 5% by weight, based on the total multiphase propylene copolymer. Preferably, the dispersed ethylene-α-olefin copolymer is present in an amount of 40 to 15% by weight, based on the total multiphase propylene copolymer, for example, in an amount of at least 22% by weight and / or for example, in an amount of at most 35% by weight or at most 30% by weight.

[0067] In the multiphase propylene copolymer in the composition of the present invention, the sum of the total weight of the propylene-based matrix and the total weight of the dispersed ethylene-α-olefin copolymer can be at least 95% by weight, at least 97% by weight, at least 99% by weight or 100% by weight of the multiphase propylene copolymer.

[0068] The α-olefin in the ethylene-α-olefin copolymer is preferably selected from the group consisting of α-olefins having 3 to 8 carbon atoms and any mixtures thereof, preferably the α-olefin in the ethylene-α-olefin copolymer is selected from the group consisting of α-olefins having 3 to 4 carbon atoms and any mixtures thereof, more preferably the α-olefin is propylene, in which case the ethylene-α-olefin copolymer is an ethylene-propylene copolymer. Examples of suitable α-olefins having 3 to 8 carbon atoms that can be used as ethylene comonomers to form the ethylene-α-olefin copolymer include, but are not limited to, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene.

[0069] The elastomer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms can have, for example, a density in the range of 0.850 to 0.915 g / cm 3 Such elastomers are sometimes also referred to as plastomers.

[0070] The α-olefin comonomer in the elastomer is preferably an acyclic monoolefin, such as 1-butene, 1-pentene, 1-hexene, 1-octene, or 4-methylpentene.

[0071] Therefore, the elastomer is preferably selected from the group consisting of ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, and mixtures thereof, more preferably the elastomer is selected from ethylene-1-octene copolymers. Most preferably, the elastomer is an ethylene-1-octene copolymer.

[0072] Preferably, the density of the elastomer is at least 0.865 g / cm 3 and / or at most 0.910 g / cm 3 . For example, the density of the elastomer is at least 0.850, for example, at least 0.865, for example, at least 0.88, for example, at least 0.90 and / or for example, at most 0.915, for example, at most 0.910, for example, at most 0.907, for example, at most 0.906 g / cm 3。More preferably, the density of the elastomer is in the range of from 0.88 to at most and including 0.907 g / cm 3 and, most preferably, the density of the elastomer is in the range of from 0.90 to at most and including 0.906 g / cm 3 .

[0073] Elastomers suitable for use in the present invention are commercially available, for example, they can be obtained from Exxon Chemical Company in Houston, Texas under the trademark EXACT TM , or from Dow Chemical Company in Midland, Michigan under the trademark ENGAGE TM polymer (a series of metallocene-catalyzed plastomers), or from the MITSUIChemicals Group in Minato, Tokyo under the trademark TAFMER TM , or from SK Chemicals under the trademark Nexlene TM .

[0074] The elastomers can be prepared using methods known in the art, for example, by using single-site catalysts, i.e., catalysts in which the transition metal component is an organometallic compound and in which at least one ligand has a cyclopentadienyl anion structure, such ligands being bonded and coordinated to the transition metal cation through said anion structure. This type of catalyst is also referred to as a "metallocene" catalyst. Metallocene catalysts are described, for example, in U.S. Patent Nos. 5,017,714 and 5,324,820. The elastomers can also be prepared using conventional types of heterogeneous multi-site Ziegler-Natta catalysts.

[0075] Preferably, the elastomer has a melt flow index of from 0.1 to 40 dg / min (ISO 1133, 2.16 kg, 190 °C), for example at least 1 dg / min and / or at most 35 dg / min. More preferably, the elastomer has a melt flow index of at least 1.5 dg / min, for example at least 2 dg / min, for example at least 2.5 dg / min, for example at least 3 dg / min, more preferably at least 5 dg / min and / or preferably at most 30 dg / min, more preferably at most 20 dg / min, more preferably at most 10 dg / min, measured according to ISO 1133 using a weight of 2.16 kg and at a temperature of 190 °C.

[0076] Preferably, the amount of ethylene incorporated into the elastomer is at least 50 mol%. More preferably, the amount of ethylene incorporated into the elastomer is at least 57 mol%, for example at least 60 mol%, at least 65 mol% or at least 70 mol%. Even more preferably, the amount of ethylene incorporated into the elastomer is at least 75 mol%. The amount of ethylene incorporated into the elastomer can typically be at most 97.5 mol%, for example at most 95 mol% or at most 90 mol%.

[0077] In some preferred embodiments, the second thermoplastic polymer in the second thermoplastic polymer composition is a mixture of a propylene homopolymer and a multiphase propylene copolymer.

[0078] Additives in the thermoplastic polymer composition of the polymer sheath

[0079] The second thermoplastic polymer composition of the polymer sheath may contain other common additives such as nucleating agents and clarifying agents, stabilizers, fillers, plasticizers, antioxidants, lubricants, antistatic agents, anti-scratch agents, impact modifiers, acid scavengers, recycling additives, coupling agents, anti-microbial agents, anti-fogging additives, slip additives, anti-blocking additives, polymer processing aids, flame retardants, colorants, and the like. Such additives are well known in the art. Those skilled in the art will know how to select the type and amount of additives such that they do not adversely affect the target properties. The amount of the additive can be, for example, 0.1 to 50% by weight of the thermoplastic polymer composition, such as 0.1 to 25% by weight or 1.0 to 5.0% by weight.

[0080] In some preferred embodiments, the additive in the thermoplastic polymer composition of the polymer sheath comprises a coupling agent.

[0081] Suitable examples of coupling agents include functionalized polyolefins grafted with acid or acid anhydride functional groups. The polyolefin is preferably polyethylene or polypropylene, more preferably polypropylene. The polypropylene can be a propylene homopolymer or a propylene copolymer. The propylene copolymer can consist of at least 70% by weight of propylene and at most 30% by weight of an α-olefin, such as ethylene, based on the total weight of the propylene-based matrix, such as at least 80% by weight of propylene and at most 20% by weight of an α-olefin, such as at least 90% by weight of propylene and at most 10% by weight of an α-olefin. Preferably, the α-olefin in the propylene-α-olefin copolymer is selected from α-olefins having 2 or 4 - 10 carbon atoms, and is preferably ethylene. Examples of acid or acid anhydride functional groups include (meth)acrylic acid and maleic anhydride. Particularly suitable materials are, for example, maleic-functionalized propylene homopolymers (such as Exxelor PO 1020 supplied by Exxon).

[0082] The amount of the coupling agent can be, for example, 0.5 to 3.0% by weight based on the sheathed continuous multifilament tow, preferably 1.0 to 2.0% by weight.

[0083] Core

[0084] The sheathed continuous multifilament tow comprises a core extending longitudinally. The core comprises at least one continuous multifilament tow.

[0085] The continuous multifilament strand comprises a plurality of coated filaments in a bundle. The continuous multifilament strand may also comprise uncoated inorganic filaments, but preferably at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt% of the multifilament strand is a coated inorganic filament according to the present invention. The continuous multifilament strand may consist of a coated inorganic filament according to the present invention.

[0086] In some embodiments, the core consists of a continuous multifilament strand (i.e., unimpregnated). In other embodiments, the core comprises or consists of an impregnated continuous multifilament strand, which comprises a continuous multifilament strand and an impregnating agent. Preferably, at least one impregnated continuous multifilament strand forms at least 90 wt%, more preferably at least 93 wt%, even more preferably at least 95 wt%, even more preferably at least 97 wt%, even more preferably at least 98 wt%, such as at least 99 wt% of the core.

[0087] In the context of the present invention, 'extending longitudinally' means 'oriented in the direction of the long axis of the sheathed continuous multifilament strand'.

[0088] Inorganic filaments of the sheathed continuous multifilament strands of the core

[0089] The continuous multifilament strand comprises a plurality of coated filaments in a bundle. Each of the coated filaments is a coated filament comprising an inorganic filament and a first polymer composition containing a first thermoplastic polymer, wherein the first polymer composition is in direct contact with the filament.

[0090] Since the first polymer composition is in direct contact with the filament, this means that there is no component between the surface of the glass filament and the coating, and thus this means that there is no adhesion promoter, sizing agent or similar compound between the first polymer composition and the inorganic filament. Typically in conventional methods, an adhesion promoter or sizing agent is first applied to the inorganic filament before coating with the polymer composition.

[0091] The method described below eliminates the need for a coating such as an adhesion promoter between the glass filament and the first polymer composition.

[0092] The inorganic fibrils can be mineral materials such as engineering glasses (electrical glass (E-glass, an aluminoborosilicate glass with less than 1 wt% alkali metal oxide); A-glass (alkali metal-lime glass with little or no boron oxide); AR-glass; electrical / chemical resistance glass (E-CR glass, an alumina-lime-silicate glass with less than 1 wt% alkali metal oxide and high acid resistance); C-glass (alkali metal-lime glass with a high boron oxide content, also known as T-glass); D-glass (borosilicate glass with a low dielectric constant); R-glass (aluminosilicate glass without MgO and CaO); S-glass (aluminosilicate glass without CaO but with a high MgO content); M-glass; or basalt; kaolin; alkaline earth metal silicate (AES, a combination of CaO, MgO, and SiO2); refractory ceramic fiber (RCF, also known as aluminosilicate, ASW); polycrystalline wool (PCW, containing more than 70% alumina); alumina; metallic materials (steel alloys; aluminum alloys; copper alloys, platinum alloys, and pure platinum, especially alloys with rhodium).

[0093] Preferred inorganic fibrils are glass fibrils, such as fibrils of E-glass or E-CR glass.

[0094] The first polymer composition comprises a first thermoplastic polymer, for example, in an amount of at least 95 wt%, for example, in an amount of at least 96 wt%, preferably in an amount of at least 97 wt%, for example, in an amount of at least 98.5 wt% based on the first polymer composition, and may optionally contain additives, for example, in an amount of 0.1 to 5.0 wt% based on the first polymer composition.

[0095] Preferably, the first polymer composition comprises at least 95 wt%, for example, at least 96 wt%, preferably at least 97 wt%, for example, at least 98.5 wt% of the first thermoplastic polymer based on the first polymer composition, and / or wherein the first thermoplastic polymer is selected from acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polyethylene (PE), polyolefin elastomer (POE), polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), polybutadiene (BR), ethylene propylene diene monomer (EPDM), polyamide (PA), thermoplastic polyurethane (TPU), and mixtures thereof, preferably wherein the first thermoplastic polymer is polypropylene.

[0096] The first thermoplastic polymer may be selected from: polymers soluble in chloroform, carbon tetrachloride or 1-bromonaphthalene, such as acrylic polymers (acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylate (ASA), polyisobutyl methacrylate (PiBMA), poly-n-butyl methacrylate (PnBMA), polyethyl methacrylate (PEMA), polymethyl methacrylate (PMMA)), cellulose acetate butyrate (CAB), fluorinated ethylene propylene (FEP), polyamides (PA) such as polyamide 12 (PA-12), polybutadiene, polycarbonates (PC) such as bisphenol A polycarbonate, polychlorotrifluoroethylene (PCTFE), polyimides such as polyetherimide (PEI), polysulfones such as polyethersulfone (PES), polyethylene (PE) such as UHMWPE, HMWPE, HDPE, LLDPE, LDPE, polyethylene terephthalate (PET), polyisobutene (PiB, butyl rubber), polyisoprene (PiP), polylactic acid (PLA), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polypropylene (PP), atactic PP, isotactic PP, polystyrene (PS), polysulfone (PSU), polyurethane (PU), polyvinyl acetate (PVA), polyvinyl butyral, polyvinyl chloride (PVC), bromine-soluble polymers, acrylic polymers, polyethyl methacrylate (PEMA), polymethyl methacrylate (PMMA), cellulose acetate (CA), cellulose acetate butyrate (CAThB), cellulose nitrate (nitrocellulose), polycarbonate (PC), bisphenol A polycarbonate, polyphenylene oxide (PPO), polyurethane (PU), polyvinyl acetate (PVA).

[0097] Preferably, the first polymer composition has a melt viscosity of at most 25 Pa·s, preferably in the range of 1.0 to 25 Pa·s, more preferably in the range of 1.0 to 20 Pa·s, even more preferably in the range of 1.8 to 19.4 Pa·s or in the range of 1.0 to 15 Pa·s, even more preferably in the range of 1.0 to 10 Pa·s, and most preferably 1.0 to 5.0 Pa·s at the melting temperature of the polymer composition, where the melting temperature of the polymer composition is determined on the second heating curve using differential scanning calorimetry with a heating and cooling rate of 10 °C / min for a 5 mg sample and where the melt viscosity is determined according to ISO6721-10:2015 by applying oscillatory shear to the molten sample at an angular frequency of 1 rad / s and a shear strain of 5%.

[0098] The first polymer composition may comprise or may be a polypropylene composition, the polypropylene composition comprising A) graft polypropylene grafted with C1) a side chain compound capable of forming hydrogen bonds, and / or

[0099] B) Ungrafted polypropylene and C2) a compound capable of forming hydrogen bonds,

[0100] wherein the total amount of A) and B) is at least 70% by weight relative to the polypropylene composition, and the polypropylene composition comprises an amount of D) low molecular weight polyethylene, such as a low molecular weight polyolefin having a molecular weight of at most 5000 g / mol, of less than 10% by weight relative to the polypropylene composition.

[0101] The use of an adhesion promoter, preferably a side-chain compound capable of forming hydrogen bonds or / and a compound capable of forming hydrogen bonds, in the polymer composition improves the adhesion between the polymer composition and the inorganic filaments. Surprisingly, it has been found that coated filaments can be produced in which the adhesion promoter is incorporated into the polymer composition itself rather than as an intermediate layer. This simplifies the production process.

[0102] The coated inorganic filaments can be in the form of individual inorganic filaments provided with a coating. In this case, the coating can be provided on substantially all or part of the surface of the inorganic filaments. The coated inorganic filaments can be in the form of a plurality of inorganic filaments (partially) bundled together. In this case, the coating may be absent on the parts of the inorganic filaments in contact with each other.

[0103] The coated glass filaments comprise a coating of a first polymer composition, preferably a polypropylene composition, provided directly on the glass filaments.

[0104] Preferably, the polypropylene composition used comprises C1) a side-chain compound capable of forming hydrogen bonds (as part of the grafted polypropylene) and / or C2) a compound capable of forming hydrogen bonds. The presence of C1) and / or C2) in the polypropylene composition improves the adhesion to the glass fibers. Compounds C1) and C2) have a hydrogen atom or a functional group that generates a hydrogen atom through (partial) hydrolysis of the functional group, which can form hydrogen bonds with the glass filaments. The hydrogen bonds improve the adhesion between the polypropylene composition and the glass filaments. In some cases, in addition to forming hydrogen bonds, a condensation reaction between the silanol groups on the glass surface and the hydrogen atoms can produce ester bonds or ether bonds and thus result in covalent bonds with the glass surface.

[0105] Preferably, the polypropylene composition comprises

[0106] - A) grafted polypropylene grafted with C1) a side-chain compound selected from acid anhydrides (such as maleic anhydride, itaconic anhydride), vinyl oligosilanes, acryloxy oligosilanes, epoxy (meth)acrylates, and combinations thereof;

[0107] - A) grafted polypropylene grafted with C1) a side-chain compound selected from acid anhydrides (such as maleic anhydride, itaconic anhydride), vinyl oligosilanes, acryloxy oligosilanes, epoxy (meth)acrylates, and combinations thereof, and

[0108] B) Ungrafted polypropylene;

[0109] - A) Grafted polypropylene grafted with a side chain compound selected from C1) acid anhydrides (e.g., maleic anhydride, itaconic anhydride), vinyl oligosilanes, acryloyloxy oligosilanes, epoxy (meth)acrylates, and combinations thereof,

[0110] B) Ungrafted polypropylene, and

[0111] C2) Compounds selected from oligosilanes (e.g., vinyl oligosilanes, aminopropyl oligosilanes, acryloyloxy oligosilanes), copolymers of ethylene and 2-hydroxyethyl methacrylate, epoxy (meth)acrylates, polyamides, organometallic compounds having pyrophosphate groups, and combinations thereof; or

[0112] - B) Ungrafted polypropylene, and

[0113] C2) Compounds selected from vinyl oligosilanes, acryloyloxy oligosilanes, copolymers of ethylene and 2-hydroxyethyl methacrylate, epoxy (meth)acrylates, organometallic compounds having pyrophosphate groups, and combinations thereof.

[0114] A) Grafted polypropylene

[0115] The polypropylene composition used may contain grafted polypropylene. The grafted polypropylene is polypropylene grafted with a side chain compound C1) capable of forming hydrogen bonds.

[0116] Suitable examples of C1) include acid anhydrides (e.g., maleic anhydride, itaconic anhydride), oligosilanes (e.g., vinyl oligosilanes, aminopropyl oligosilanes, acryloyloxy oligosilanes), epoxy (meth)acrylates, polyamides, and combinations thereof. Those skilled in the art know how to obtain A) by grafting C1) onto polypropylene. When C1) is maleic anhydride, the double bond of maleic anhydride is consumed for grafting, and a succinic anhydride bond with polypropylene is formed.

[0117] An example of the epoxy (meth)acrylate is glycidyl methacrylate.

[0118] Preferably, C1) includes acid anhydrides (e.g., maleic anhydride, itaconic anhydride). Most preferably, C1) includes maleic anhydride. This results in good adhesion between the polypropylene composition and the fibrils.

[0119] Preferably, the amount of C1) is 0.5 to 10% by weight, such as 0.6 to 5.0% by weight, 0.7 to 3.0% by weight, 0.8 to 2.0% by weight, based on the amount of A).

[0120] C2) Compounds capable of forming hydrogen bonds

[0121] The polypropylene composition used may comprise B) ungrafted polypropylene and C2) a compound capable of forming hydrogen bonds. Preferably, C2) has an unsaturated group capable of reacting with ungrafted polypropylene to form hydrogen bonds, or C2) has a hydrophobic group (such as a copolymer of ethylene and 2-hydroxyethyl methacrylate (PE-HEMA)).

[0122] Suitable examples of C2) include oligosilanes (such as vinyl oligosilanes, aminopropyl oligosilanes, acryloyloxy oligosilanes), a copolymer of ethylene and 2-hydroxyethyl methacrylate (PE-HEMA), epoxy (meth)acrylates, polyamides, organometallic compounds having pyrophosphate groups, and combinations thereof.

[0123] When the polypropylene composition comprises A), C2) is preferably a compound selected from oligosilanes (such as vinyl oligosilanes, aminopropyl oligosilanes, acryloyloxy oligosilanes), a copolymer of ethylene and 2-hydroxyethyl methacrylate (PE-HEMA), epoxy (meth)acrylates, polyamides, organometallic compounds having pyrophosphate groups, and combinations thereof.

[0124] When the polypropylene composition does not comprise A), C2) is preferably a compound selected from vinyl oligosilanes, acryloyloxy oligosilanes, a copolymer of ethylene and 2-hydroxyethyl methacrylate, epoxy (meth)acrylates, organometallic compounds having pyrophosphate groups, and combinations thereof.

[0125] Preferably, C2) is selected from oligosilanes (such as vinyl oligosilanes, aminopropyl oligosilanes, acryloyloxy oligosilanes), organometallic compounds having pyrophosphate groups, and combinations thereof. This results in good adhesion between the polypropylene composition and the fibrils.

[0126] Preferably, C2) comprises a vinyl oligosilane or an acryloyloxy oligosilane, more preferably a vinyl oligosilane. This results in particularly good adhesion between the polypropylene composition and the fibrils.

[0127] It has been found that the oligosilane has a low enough volatility to react with polypropylene to achieve the desired effect.

[0128] Preferably, the polypropylene composition does not contain or substantially does not contain alkoxysilane compounds having a molecular weight of less than 300 (such as γ-aminopropyltriethoxysilane (APTES), γ-glycidoxypropyltrimethoxysilane (GPTMS), γ-methacryloxypropyltrimethoxysilane (MPTMS), vinyltriethoxysilane (VTES)). Preferably, the amount of such alkoxysilane compounds having a molecular weight of less than 300 is less than 10% by weight, less than 5.0% by weight, less than 3.0% by weight, less than 1.0% by weight, less than 0.5% by weight or 0% by weight based on the polypropylene composition.

[0129] Preferably, C2) comprises an organometallic compound having a pyrophosphate group, preferably a titanate pyrophosphate compound or a zirconate pyrophosphate compound. This results in particularly good adhesion between the polypropylene composition and the fibrils. Suitable examples include neopentyl(diallyl)oxytris(dioctyl)pyrophosphatooxy titanate, cyclo(dioctyl)pyrophosphate dioctyl titanate, dicyclo(dioctyl)pyrophosphate titanate, neopentyl(diallyl)oxytris(N-ethylethylenediamino)ethyl titanate, cyclo[bis(neopentyl(diallyl))]pyrophosphatooxy bis(neopentyl(diallyl)) zirconate, bis(dioctyl)pyrophosphate oxoethylene titanate and the 2-(N,N-dimethylamino)isobutanol adduct of bis(dioctyl)pyrophosphate oxoethylene titanate.

[0130] Preferably, the amount of C2) is 0.2 to 10% by weight, such as 0.3 to 5.0% by weight, 0.4 to 3.0% by weight, 0.5 to 2.0% by weight based on the total amount of B) and C2).

[0131] D) Low molecular weight polyolefin

[0132] The polypropylene composition comprises D) low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol in an amount of less than 10% by weight based on the polypropylene composition. It should be appreciated that this includes the case where the polypropylene composition does not contain D) low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol. If the polypropylene composition contains D) low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol, its amount is less than 10% by weight based on the polypropylene composition. Thus, this feature can also be expressed as "the amount of D) low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol in the polypropylene composition is less than 10% by weight based on the polypropylene composition".

[0133] Preferably, the polypropylene composition does not contain or substantially does not contain low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol. Preferably, the amount of such low molecular weight polyethylene relative to the polypropylene composition is less than 10 wt%, less than 5.0 wt%, less than 3.0 wt%, less than 1.0 wt%, less than 0.5 wt% or 0 wt%.

[0134] Preferably, the polypropylene composition does not contain or substantially does not contain low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol. For example, the amount of such low molecular weight polyolefin (the sum of low molecular weight polyethylene having a number average molecular weight of at most 5000 g / mol and any other polyolefin having a number average molecular weight of at most 5000 g / mol) relative to the polypropylene composition is less than 10 wt%, less than 8.0 wt%, less than 5.0 wt%, less than 3.0 wt%, less than 1.0 wt%, less than 0.5 wt% or 0 wt%.

[0135] Additives

[0136] The first polymer composition may additionally contain additives such as flame retardants, pigments, lubricants, slip agents, flow promoters, antistatic agents, processing stabilizers, long-term stabilizers and / or UV stabilizers. The amount of the additives may be, for example, 0.1 to 5.0 wt%.

[0137] Preferably, the total amount of A), B), C2), D) and the additives is 100 wt% based on the first polymer composition.

[0138] Preferred polypropylene composition

[0139] Preferably, the polypropylene composition has a melt viscosity of at most 25 Pa·s at the melting temperature of the polymer composition, preferably in the range of 1.0 to 25 Pa·s, more preferably in the range of 1.0 to 20 Pa·s, even more preferably in the range of 1.8 to 19.4 Pa·s or in the range of 1.0 to 15 Pa·s, even more preferably in the range of 1.0 to 10 Pa·s, and most preferably 1.0 to 5.0 Pa·s, where the melting temperature of the polymer composition is determined for a 5 mg sample using a heating and cooling rate of 10 °C / min on the second heating curve by differential scanning calorimetry and where the melt viscosity is determined according to ISO 6721-10:2015 by applying oscillatory shear to the molten sample at an angular frequency of 1 rad / s and a shear strain of 5%.

[0140] In some preferred embodiments, the amount of A) is at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt% or 100 wt% based on the polypropylene composition.

[0141] In some preferred embodiments, the total amount of B) and C2) is at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt% or 100 wt% based on the polypropylene composition.

[0142] In some preferred embodiments, the polypropylene composition comprises A) and B). Preferably, the total amount of A) and B) is at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 93 wt%, at least 95 wt%, at least 97 wt%, at least 99 wt% or 100 wt% based on the polypropylene composition. Preferably, the amount of A) is 1.0 to 30 wt% based on the total amount of A) and B), such as 2.0 to 25 wt%, 3.0 to 20 wt% or 4.0 to 10 wt%.

[0143] In some preferred embodiments, the polypropylene composition comprises A), B) and C2). Preferably, the amount of B) is at least 65 wt% based on the total amount of A), B) and C2). Preferably, the amount of A) is 1.0 to 30 wt% based on the total amount of A) and B), such as 2.0 to 25 wt%, 3.0 to 20 wt% or 4.0 to 10 wt%. Preferably, the amount of C2) is 0.2 to 10 wt% based on the total amount of B) and C2), such as 0.3 to 5.0 wt%, 0.4 to 3.0 wt%, 0.5 to 2.0 wt%. In a particularly preferred embodiment, based on the total amount of A), B) and C), the amount of A) is 1.0 to 5.0 wt%, the amount of B) is 90 to 98 wt%, and the amount of C) is 1.0 to 5.0 wt%.

[0144] In a particularly preferred embodiment, wherein the polypropylene composition comprises A), B) and C2), C1) is selected from acid anhydrides (such as maleic anhydride, itaconic anhydride) and C2) comprises an organometallic compound having a pyrophosphate group, preferably a titanate pyrophosphate compound or a zirconate pyrophosphate compound.

[0145] In some embodiments, after obtaining a bundle of multiple coated filaments, the sizing composition is applied to the bundle. In these cases, the continuous multifilament comprises the sizing composition provided on the multiple coated filaments in the bundle. It should be appreciated that there is no such sizing composition between the glass filaments and the first polymer composition.

[0146] The sizing composition may comprise a silane compound, which may be a tris(C 1-6 alkoxy)monoaminosilane, tris(C 1-6 alkoxy)diaminosilane, tris(C 1-6 alkoxy)(C 1-6 alkylureido)silane, tris(C 1-6 alkoxy)(epoxy C 1-6 alkyl)silane, tris(C 1-6 alkoxy)(glycidyl-oxy C 1-6 alkyl)silane, tris(C 1-6 alkoxy)(mercapto C 1-6 alkyl)silane, or combinations thereof. For example, the silane compound is (3-aminopropyl)triethoxysilane, (3-glycidyl-oxypropyl)trimethoxysilane, (2-(3,4-epoxycyclohexyl)ethyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-(2-aminoethylamino)propyl)triethoxysilane, (3-ureidopropyl)triethoxysilane, or combinations thereof.

[0147] In some embodiments, the continuous multifilament is free of the sizing composition. After obtaining a bundle of the coated filaments, the continuous multifilament is directly provided with a polymer sheath or directly impregnated with an impregnating agent.

[0148] Core without sizing agent

[0149] In some embodiments, the core is substantially free of the impregnating agent. A particular advantage of the absence of the impregnating agent in the composition is the simplicity of the method and the reduction of volatile compounds.

[0150] This is achieved by a method for preparing a fiber-reinforced thermoplastic polymer composition, wherein step c) is carried out directly after step a) without step b).

[0151] Such a core is described, for example, in WO2022128783A1.

[0152] Preferably, the sheathed continuous multifilament strand comprises an amount of polyethylene wax of less than 0.50 wt%, preferably less than 0.40 wt%, less than 0.30 wt%, less than 0.20 wt%, less than 0.10 wt%, less than 0.05 wt%, less than 0.01 wt%, or 0.00 wt% relative to the sheathed continuous multifilament strand, the polyethylene wax having a melting point of 50 to 100 °C, an MW of 5 to 10 kg / mol, and a polydispersity index (MWD) of 5 to 10. Examples of such polyethylene waxes are commercially available as Dicera13082Paramelt, which is a highly branched polyethylene wax.

[0153] Preferably, the sheathed continuous multifilament tow contains an amount of polyethylene wax having an MW of at most 10 kg / mol of less than 0.50% by weight, preferably less than 0.40% by weight, less than 0.30% by weight, less than 0.20% by weight, less than 0.10% by weight, less than 0.05% by weight, less than 0.01% by weight or 0.00% by weight, based on the sheathed continuous multifilament tow.

[0154] Preferably, the sheathed continuous multifilament tow contains an amount of polyethylene wax of less than 0.50% by weight, preferably less than 0.40% by weight, less than 0.30% by weight, less than 0.20% by weight, less than 0.10% by weight, less than 0.05% by weight, less than 0.01% by weight or 0.00% by weight, based on the sheathed continuous multifilament tow, said polyethylene wax having a melting point at least 20 °C lower than that of the polyolefin in the thermoplastic composition and a viscosity of 2.5 to 100 cS, said viscosity being measured at 160 °C by ASTM D 3236-15 (Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials, Brookfield Viscometer, Model RVDV 2, #27 Spindle, 5 r / min).

[0155] Preferably, the sheathed continuous multifilament tow contains an amount of less than 0.50% by weight, preferably less than 0.40% by weight, less than 0.30% by weight, less than 0.20% by weight, less than 0.10% by weight, less than 0.05% by weight, less than 0.01% by weight or 0.00% by weight, based on the sheathed continuous multifilament tow, of microcrystalline polyethylene wax having at least one of the following properties:

[0156] - a dropping melting point of 60 to 90 °C as determined according to ASTM D127

[0157] - a solidification point of 55 to 90 °C as determined according to ASTM D938

[0158] - a needle penetration at 25 °C of 7 / 10 to 40 mm as determined according to ASTM D1321

[0159] - a viscosity at 100 °C of 10 to 25 mPa·s as determined according to ASTM D445, and

[0160] - an oil content of 0 to 5% by weight based on the weight of the microcrystalline wax as determined according to ASTM D721.

[0161] Preferably, the core consists essentially of at least one continuous multifilament. Preferably, the amount of the at least one continuous multifilament is at least 99.50 wt%, at least 99.60 wt%, at least 99.70 wt%, at least 99.80 wt%, at least 99.90 wt%, at least 99.95 wt%, at least 99.99 wt% or 100.00 wt% based on the core.

[0162] Preferably, the core consists essentially of coated filaments. Preferably, the amount of the coated filaments is at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.50 wt%, at least 99.60 wt%, at least 99.70 wt%, at least 99.80 wt%, at least 99.90 wt%, at least 99.95 wt%, at least 99.99 wt% or 100.00 wt% based on the core.

[0163] Core containing sizing agent

[0164] In some embodiments, the core comprises an impregnated continuous multifilament strand containing at least one continuous multifilament strand impregnated with an impregnating agent. This is achieved by a method for preparing a fiber-reinforced thermoplastic polymer composition, the method comprising b) applying the impregnating agent to at least one continuous multifilament strand.

[0165] Suitable examples and amounts of the impregnating agent are described, for example, in WO2021156115A1.

[0166] An impregnated continuous multifilament strand is prepared from a continuous multifilament strand and an impregnating agent, and in particular by applying the impregnating agent to the continuous multifilament strand, preferably in an amount of 0.50 to 18.0% by weight, such as 0.5 to 10.0% by weight or such as 10.0 to 18.0% by weight, based on the sheathed continuous multifilament strand. The optimum amount of the impregnating agent applied to the continuous multifilament strand depends on the polymer sheath, the size (diameter) of the filaments forming the continuous glass strand, and the type of sizing composition. Typically, the amount of the impregnating agent applied to the continuous multifilament strand is, for example, at least 0.50% by weight, preferably at least 1.0% by weight, preferably at least 1.5% by weight, preferably at least 2% by weight, preferably at least 2.5% by weight and / or at most 10.0% by weight, preferably at most 9.0% by weight, more preferably at most 8.0% by weight, even more preferably at most 7.0% by weight, even more preferably at most 6.0% by weight, even more preferably at most 5.5% by weight, or such as at least 10.0% by weight, preferably at least 11% by weight, preferably at least 12% by weight and / or at most 18% by weight, preferably at most 16% by weight, preferably at most 14%. Preferably, the amount of the impregnating agent is in the range of 1.5 to 8% by weight, even more preferably in the range of 2.5% to 6.0% by weight, based on the sheathed continuous multifilament strand. A higher amount of the impregnating agent increases the impact energy per unit thickness (J / mm). However, for reasons of cost-effectiveness and low emissions (volatile organic compounds) and mechanical properties, the amount of the impregnating agent should not become too high.

[0167] For example, the ratio of the impregnating agent to the continuous multifilament strand is in the range of 1:4 to 1:30, preferably in the range of 1:5 to 1:20.

[0168] Preferably, the viscosity of the impregnating agent is in the range of 2.5 to 200 cSt at 160 °C, more preferably at least 5.0 cSt, more preferably at least 7.0 cSt and / or at most 150.0 cSt at 160 °C, preferably at most 125.0 cSt, preferably at most 100.0 cSt.

[0169] Impregnants having a viscosity above 100 cSt are difficult to apply to continuous multifilament strands. A low viscosity is required to promote good wetting properties of the fibers, but an impregnating agent having a viscosity below 2.5 cSt is difficult to handle; for example, the amount to be applied is difficult to control; and the impregnating agent may become volatile. For the purposes of the present invention, unless otherwise stated, the viscosity of the impregnating agent is measured at 160 °C in accordance with ASTM D3236-15 (Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials, Brookfield viscometer, model RVDV2, #27 rotor, 5 r / min). Preferably, the melting point of the impregnating agent (i.e., the lowest melting temperature within the melting temperature range) is at least 20 °C lower than the melting point of the thermoplastic polymer composition. More preferably, the impregnating agent has a melting point at least 25 or 30 °C lower than the melting point of the thermoplastic polymer composition. For example, when the thermoplastic polymer composition has a melting point of about 160 °C, the melting point of the impregnating agent can be at most about 140 °C. Suitable impregnating agents are compatible with the thermoplastic polymer to be reinforced and may even be soluble in the polymer. A person skilled in the art can select a suitable combination based on common general knowledge and such combinations can also be found in the art. Suitable examples of impregnating agents include low molar mass compounds such as low molar mass oligomeric polyurethanes, polyesters such as unsaturated polyesters, polycaprolactones, polyethylene terephthalate, poly(α-olefins) such as highly branched polyethylenes and polypropylenes, polyamides such as nylons and other hydrocarbon resins.

[0170] For reinforcing polypropylene, the impregnating agent preferably comprises a highly branched poly(α-olefin) such as highly branched polyethylene, a modified low molecular weight polypropylene, a mineral oil such as paraffin or silicone and any mixture of these compounds.

[0171] The impregnating agent preferably comprises at least 20 wt%, more preferably at least 30 wt%, more preferably at least 50 wt%, for example at least 99.5 wt%, for example 100 wt% of a branched poly(α-olefin), most preferably branched polyethylene.

[0172] To achieve a viscosity of 2.5 to 200 cSt for the impregnating agent at 160 °C, a branched poly(α-olefin) can be mixed with an oil, where the oil is selected from mineral oils such as paraffin oil or silicone oil; hydrocarbon oils; and any mixture thereof. Preferably, the impregnating agent is non-volatile and / or substantially solvent-free. In the context of the present invention, non-volatile means that the impregnating agent has a boiling point or boiling range higher than the temperature at which the impregnating agent is applied to the continuous multifilament strand. In the context of the present invention, "substantially solvent-free" means that, based on the impregnating agent, the impregnating agent contains less than 10% by weight of solvent, preferably less than 5% by weight of solvent. In a preferred embodiment, the impregnating agent does not contain any organic solvents. The impregnating agent can additionally be mixed with other additives known in the art. Suitable examples include lubricants; antistatic agents; UV stabilizers; plasticizers; surfactants; nucleating agents; antioxidants; pigments; dyes; and adhesion promoters such as maleated modified polypropylene; and any combination thereof, provided that the viscosity remains within the desired range. Any method known in the art can be used to apply the liquid impregnating agent to the continuous multifilament strand. The application of the liquid impregnating agent can be carried out using a die. Other suitable methods for applying the impregnating agent to the continuous multifilament strand include applicators with belts, rollers, and hot melt applicators. Such methods are described, for example, in the documents EP0921919B1, EP0994978B1, EP0397505B1, WO2014 / 053590A1 and the references cited therein. The method used should be able to apply a constant amount of the impregnating agent to the continuous multifilament strand.

[0173] Preferably, the amount of the impregnated continuous multifilament strand is 25 to 75% by weight, for example 25 to 40% by weight, 40 to 55% by weight or 55 to 75% by weight, based on the sheathed continuous multifilament strand. Preferably, the total amount of the impregnated continuous multifilament strand and the polymer sheath is 100% by weight, based on the sheathed continuous multifilament strand.

[0174] Other suitable examples of the impregnating agent include aromatic phosphates, polyphosphonates, and poly(phosphonate-co-carbonate).

[0175] Preferably, the aromatic phosphates are selected from the group consisting of:

[0176] Resorcinol bis(diphenyl phosphate);

[0177] Tetraphenyl resorcinol bis(diphenyl phosphate);

[0178] Bisphenol A bis(diphenyl phosphate);

[0179] Bisphenol A diphosphate;

[0180] Resorcinol bis(di-2,6-dimethylphenyl phosphate);

[0181] Mixed esters of phosphoric acid with [1,1'-biphenyl]-4,4'-diol and phenol;

[0182] Polymer of phosphorus oxychloride with 1,3-benzenediol, phenyl ester;

[0183] 1,3-Phenylene-tetrakis(2,6-dimethylphenyl) diphosphate;

[0184] Diphenyl isopropenylphenyl phosphate;

[0185] Phenyl 4-phenylphenolformaldehyde phosphonate;

[0186] Tris(2,6-xylyl) phosphate;

[0187] Resorcinol bis(di-2,6-xylyl phosphate);

[0188] Bisphenol S bis(diphenyl phosphate); and

[0189] Resorcinol-bisphenol A phenyl phosphate, and

[0190] Combinations thereof,

[0191] Preferably, the aromatic phosphate is bisphenol A bis(diphenyl phosphate).

[0192] In a particularly preferred embodiment, the inorganic filaments are glass filaments, the first thermoplastic polymer is polypropylene, and the second thermoplastic polymer is polypropylene, and

[0193] The core is substantially free of sizing and / or the sheath continuous multifilament strand contains less than 0.50 wt% of a polyethylene wax having a melting point of 50 to 100 °C, an MW of 5 to 10 kg / mol and a polydispersity index (MWD) of 5 to 10.

[0194] Other aspects

[0195] The present invention provides pellets comprising or consisting of a fiber-reinforced thermoplastic polymer composition according to the present invention.

[0196] The pellets can typically have a length of 2 to 50 mm, preferably 5 to 30 mm, more preferably 6 to 20 and most preferably 10 to 16 mm. The length of the filaments is typically substantially the same as the length of the pellets.

[0197] The total amount of the second thermoplastic polymer composition, the continuous multifilament strand and optionally the sizing in the pellets is preferably at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt% based on the pellets.

[0198] The granulates can be formed into (semi-)finished products. Suitable examples of forming processes include injection molding, compression molding, extrusion (optionally followed by thermoforming), and coextrusion compression molding. The forming can be carried out by melting and forming the granulates according to the invention, with or without the addition of further polymers (in the form of granulates).

[0199] The invention further relates to a formed article comprising a fiber-reinforced thermoplastic polymer composition.

[0200] The formed article can be an injection-molded article. The article can be selected from automotive exterior parts such as bumpers and tailgates, automotive interior parts such as instrument panels, and automotive parts under the engine hood. The article can also be selected from components and housings of air conditioners, dishwashers, washing machines, dryers, coffee machines, power tools (such as saws, drills), durable goods (such as furniture), 5G antennas, solar panels, bicycles, and pedals.

[0201] The formed article can be an extruded and optionally thermoformed article, where the article is selected from scaffolds, battery trays, building frames, and floors.

[0202] The invention further relates to a method for preparing a formed article by melt-mixing and forming the fiber-reinforced thermoplastic polymer composition (in the form of granulates) according to the invention.

[0203] The invention further relates to a method for preparing a formed article by melting and forming the fiber-reinforced thermoplastic polymer composition (in the form of granulates) according to the invention and further polymers (in the form of granulates). Preferably, the amount of the multifilament strands is 50 to 80% by weight relative to the sheathed continuous multifilament strands. Suitable examples of such further polymers are the propylene-based polymers described for the thermoplastic polymer composition of the polymer sheath. WO2022 / 128784 describes suitable examples of such further polymers as "further propylene-based polymers", which are incorporated herein by reference.

[0204] It should be noted that the invention relates to the subject matter defined by the independent claims alone or in combination with any possible combinations of the features described herein, preferably in particular those combinations of the features presented in the claims. Thus, it is to be understood that all combinations of features relating to the composition according to the invention, all combinations of features relating to the method according to the invention, and all combinations of features relating to the composition according to the invention and features relating to the method according to the invention are described herein.

[0205] It should be further noted that the terms 'comprising', 'including', 'containing' do not exclude the presence of other elements. However, it should also be understood that the description of a product / composition containing certain components also discloses a product / composition consisting of these components. The product / composition consisting of these components may be advantageous as it provides a simpler and more economical method for preparing the product / composition. Similarly, it should also be understood that the description of a method including certain steps also discloses a method consisting of these steps. The method consisting of these steps may be advantageous as it provides a simpler and more economical method.

[0206] The present invention will now be illustrated by means of the following examples, but the present invention is not limited thereto. Examples

[0207] Materials used

[0208] GF1: A glass roving having a diameter of 19 microns and 3000 tex (tex means grams of glass per 1000 meters), which contains a sizing composition containing a silane coupling agent.

[0209] GF2: A continuous glass multifilament bundle (package) of multiple bundled coated glass filaments. The coated glass filaments contain glass filaments and a coating of a polypropylene composition directly provided on the glass filaments. The amount of the polypropylene composition is about 4.5% by weight based on the continuous glass multifilament. The polypropylene composition contains 10% by weight of Bondyram 1010 from Bondyram (polypropylene grafted with maleic anhydride), 15% by weight of PP595A from SABIC (an isotactic polypropylene having an MFR of 47 dg / min according to ISO1133 at 230 °C and 2.16 kg), and 75% by weight of PP514M12 from SABIC (an isotactic polypropylene having an MFR of >1000 dg / min according to ISO1133 at 230 °C and 2.16 kg). A sizing composition containing an aminosilane compound is further provided to the bundle coated with the polypropylene composition.

[0210] Impregnant 1: A wax commercially available as IGIParaflex 4838A

[0211] PP1: SABIC PP 595A isotactic polypropylene, having the following properties: density: 905 kg / m 3 , melt flow index: 45 dg / min at 230 °C and 2.16 kg (test method: ISO1133)

[0212] Exxelor PO1020: Polypropylene grafted with maleic anhydride, from ExxonMobil: density: 900 kg / m3 , Melting point: 162 °C, Melt Flow Index: 430 dg / min at 230 °C and 2.16 kg (Test method: ASTM D1238)

[0213] AO1076: Antioxidant 1076, from BASF

[0214] AOB225: Antioxidant B225, from BASF

[0215] UV119: UV stabilizer UV 119, from SABO SpA

[0216] UV770: UV stabilizer UV 770, from BASF

[0217] CMB Black: Masterbatch from Ampacet

[0218] CEx 1

[0219] Using the wire coating method described in detail in the examples of WO2009 / 080281A1, pellets of sheathed continuous multifilament strands are prepared using the components given in Table 1. Impregnating agent 1 is applied to GF1 to obtain impregnated continuous glass multifilament strands.

[0220] The polypropylene and additives shown in Table 1 are fed into an extruder to sheath the impregnated continuous glass multifilament strands using an extruder head wire coating die. The sheathing step is carried out directly online after the impregnation step. The obtained sheathed continuous multifilament strands are cut into pellets having a length of 8 - 15 mm and a diameter of 3 - 4 mm. The obtained pellets are molded using an ARBURG 320T injection molding machine to prepare samples for testing.

[0221] Ex 2

[0222] Pellets of sheathed continuous multifilament strands are prepared using the method as in CEx 1 with the components given in Table 1, except that the step of applying the impregnating agent is not carried out.

[0223] The following properties are measured and shown in Table 1.

[0224] The flexural properties are tested according to ISO178 after aging at 23 °C for 7 days.

[0225] The tensile properties are tested according to ISO527 after aging at 23 °C for 7 days.

[0226] Table 1

[0227] CEx 1 Ex 2 PP1 wt% 52.94 56.94 Sizing agent wt% 4 GF1 40.2 GF2 wt% 40.2 Exxelor PO 1020 2.0 2.0 AO B225 wt% 0.2 0.2 UV 119 wt% 0.06 0.06 CMB black wt% 0.6 0.6 Total wt% 100.00 100.00 Flexural modulus MPa 8195 10542 Flexural stress at break MPa 182 216 Tensile modulus MPa 8196 9890 Tensile strength MPa 117 124

[0228] The composition of Ex2 that includes GF1 (provided with a polypropylene composition instead of a sizing composition) and does not include an impregnating agent has better mechanical properties than the composition of CEx1 that includes GF2 (provided with a sizing composition) and includes an impregnating agent.

Claims

1. A fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand, said sheathed continuous multifilament strand comprising a core extending longitudinally and a polymer sheath tightly surrounding said core, wherein said core comprises at least one continuous multifilament strand, said continuous multifilament strand comprising a plurality of coated filaments bundled together, wherein each of said coated filaments is a coated filament comprising an inorganic filament and a first polymer composition comprising a first thermoplastic polymer, preferably wherein said inorganic filament is a glass filament, wherein said first polymer composition is in direct contact with said filament, wherein said polymer sheath consists of a second thermoplastic polymer composition comprising a second thermoplastic polymer.

2. The fiber-reinforced thermoplastic polymer composition according to claim 1, wherein said plurality of coated filaments bundled together can be obtained by a method comprising the following steps: i) Producing uncoated inorganic filaments from an inorganic melt; ii) Provide a melt of the first polymer composition comprising the first thermoplastic polymer; iii) Apply the melt of the first polymer composition to the uncoated inorganic filaments, preferably by using a roll die, a curtain coater die or a slot die, and solidify the melt of the first polymer composition; iv) Obtain a coated filament comprising inorganic filaments coated with the first polymer composition, wherein the inorganic filaments are in direct contact with the first polymer composition, and v) Bundle a plurality of the coated filaments.

3. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein said first polymer composition comprises at least 95% by weight of said first thermoplastic polymer based on the polymer composition, and / or wherein said first thermoplastic polymer is selected from acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylate (ASA), polyethylene (PE), polyolefin elastomer (POE), polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), polybutadiene (BR), ethylene-propylene-diene monomer (EPDM), polyamide (PA), thermoplastic polyurethane (TPU), and mixtures thereof, preferably wherein said first thermoplastic polymer is polypropylene.

4. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein said first polymer composition comprises a polypropylene composition, said polypropylene composition comprising A) grafted polypropylene grafted with C1) a side chain compound capable of forming hydrogen bonds, and / or B) ungrafted polypropylene and C2) a compound capable of forming hydrogen bonds, wherein the total amount of A) and B) is at least 70% by weight based on the polypropylene composition, and The polypropylene composition comprises, relative to the polypropylene composition, an amount of D) low molecular weight polyethylene having a molecular weight of at most 5000 g / mol of less than 10% by weight.

5. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the second thermoplastic polymer is a polyolefin, preferably wherein the polyolefin is selected from polypropylene or an elastomer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms, and any mixture thereof.

6. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the amount of the multifilament strands is 10 to 80% by weight, for example 10 to 50% by weight (such as 25 to 45% by weight) or 50 to 80% by weight (such as 60 to 75% by weight), relative to the sheathed continuous multifilament strands, and / or wherein the continuous multifilament strands are at least 99.50% by weight, at least 99.60% by weight, at least 99.70% by weight, at least 99.80% by weight, at least 99.90% by weight, at least 99.95% by weight, at least 99.99% by weight or 100.00% by weight relative to the amount of the core.

7. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the sheathed continuous multifilament strands comprise an amount of polyethylene wax of less than 0.50% by weight, preferably less than 0.40% by weight, less than 0.30% by weight, less than 0.20% by weight, less than 0.10% by weight, less than 0.05% by weight, less than 0.01% by weight or 0.00% by weight, relative to the sheathed continuous multifilament strands, the polyethylene wax having a melting point of 50 to 100 °C, an MW of 5 to 10 kg / mol and a polydispersity index (MWD) of 5 to 10.

8. The fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the first polymer composition has a melt viscosity in the range of 1.0 to 25 Pa·s at the melting temperature of the polymer composition, wherein the melting temperature of the polymer composition is determined for a 5 mg sample using a heating and cooling rate of 10 °C / min on the second heating curve by differential scanning calorimetry, and wherein the melt viscosity is determined according to ISO 6721-10:2015 by applying oscillatory shear to the molten sample at an angular frequency of 1 rad / s and a shear strain of 5%, preferably wherein the first thermoplastic polymer is polypropylene.

9. A method for preparing a fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, comprising the following sequential steps: a) unwinding the at least one continuous multifilament strand from a package, c) applying the second thermoplastic polymer around the at least one continuous multifilament strand to form the sheathed continuous multifilament strand, and Optionally d) cutting the sheathed continuous glass multifilament strands into pellets.

10. The fiber-reinforced thermoplastic polymer composition according to any one of claims 1 to 6, wherein the core comprises an impregnated continuous glass multifilament strand, and the impregnated continuous glass multifilament strand comprises at least one continuous glass multifilament strand impregnated with an impregnating agent.

11. A method for preparing the fiber-reinforced thermoplastic polymer composition according to claim 10, comprising the following sequential steps: a) unwinding the at least one continuous multifilament strand from a package, b) applying an impregnating agent to the at least one continuous multifilament strand, c) applying a sheath of the thermoplastic polymer composition around the impregnated continuous multifilament strand to form the sheathed continuous multifilament strand, and Optionally d) cutting the sheathed continuous glass multifilament strands into pellets.

12. A molded article comprising the fiber-reinforced thermoplastic polymer composition according to any one of claims 1 - 8 or claim 10.

13. The molded article according to claim 12, wherein the molded article is an injection-molded article, and preferably, the article is selected from automotive exterior components such as bumpers and tailgates; automotive interior components such as instrument panels; under-hood automotive components; and components and housings of air conditioners, dishwashers, washing machines, dryers, coffee makers, power tools (such as saws, drills), durable goods (such as furniture), 5G antennas, solar panels, bicycles, and pedals.

14. The molded article according to claim 12, wherein the molded article is an extruded and optionally thermoformed article, and preferably, the article is selected from scaffolds, battery trays, building frames, and floors.

15. A method for preparing the molded article according to any one of claims 12 to 14, which is carried out by melt-mixing and molding the fiber-reinforced thermoplastic polymer composition and an additional polymer, and preferably wherein the amount of the multifilament strands is 50 to 80% by weight based on the sheathed continuous multifilament strands.

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