CN116615486A

CN116615486A - Pellets of glass fiber reinforced thermoplastic polymer composition and method of making the same

Info

Publication number: CN116615486A
Application number: CN202180085032.4A
Authority: CN
Inventors: P·D·亚内瓦; R·吉森范; R·W·文德博什; M·索利曼; H·N·A·M·斯汀贝克斯-曼廷; A·P·阿瓦德; C·C·派雷拉
Original assignee: SABIC Global Technologies BV
Current assignee: SABIC Global Technologies BV
Priority date: 2020-12-18
Filing date: 2021-12-10
Publication date: 2023-08-18

Abstract

The present invention relates to a pellet of a glass fiber reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament bundle comprising a longitudinally extending core and a polymer sheath tightly surrounding the core, wherein the core comprises at least one continuous glass multifilament bundle, the polymer sheath is composed of a thermoplastic polymer composition comprising a polyolefin and the melt flow index measured according to ISO 1133-1:2011 (2.16 kg/230 ℃) is at least 1.0dg/min and less than 20dg/min, wherein the length of the glass filaments in the pellet is substantially equal to the length of the pellet and is 10-55mm, preferably 10-40mm, more preferably 10-30mm, most preferably 10-20mm.

Description

Pellets of glass fiber reinforced thermoplastic polymer composition and method of making the same

The present invention relates to pellets of a glass fiber reinforced thermoplastic polymer composition and a method for producing such pellets. The invention further relates to an extruded article made from such pellets. The invention further relates to a thermoformed article made from such an extruded article.

Thermoplastic polymer compositions reinforced with glass fibers are known. It is known to use short glass fibers and long glass fibers. Articles made with short glass fiber reinforced thermoplastic polymer compositions have their advantages, but articles made with long glass fiber reinforced thermoplastic polymer compositions generally have better stiffness and impact strength, as explained by Thomason & Vlug, comp Part A,1996, pages 1075-1084.

Long glass fiber reinforced thermoplastic polymer compositions, e.g. STAMAX obtained from SABIC ^TM A material, which can be manufactured by a method comprising the steps of: the wrapped continuous bundle of multifilaments is formed by unwrapping a polypropylene sheath from a package of the continuous glass bundle of multifilaments and applying the polypropylene sheath around the bundle.

Such a method is known from WO 2009/080281. This published patent application discloses a process for producing a long glass fiber reinforced thermoplastic polymer composition comprising the steps of: i) Unwinding from a package of at least one continuous glass multifilament bundle, ii) applying an impregnating agent to the at least one continuous glass multifilament bundle to form an impregnated continuous multifilament bundle, and iii) applying a thermoplastic polymer sheath around the impregnated continuous multifilament bundle to form a sheathed continuous multifilament bundle.

Thermoplastic polymer compositions reinforced by injection molding long glass fibers, such as STAMAX, are known ^TM Materials to manufacture articles. However, injection molding has design limitations in terms of the shape of the article to be manufactured. While injection molding is suitable for manufacturing articles having complex three-dimensional shapes, it is not suitable for manufacturing hollow articles. Hollow articles may be suitably manufactured by extrusion rather than injection moulding.

Accordingly, there is a need in the art for long glass fiber reinforced thermoplastic polymer compositions suitable for extrusion.

Extrusion of long glass fiber reinforced thermoplastic polymer compositions is disclosed in WO 2009/054716. In an embodiment, the long glass fiber reinforced thermoplastic polymer composition "STAMAX 60YM240" is mixed with another polypropylene homo-or copolymer and the mixture is extruded. STAMAX 60YM240 has a core of glass multifilament bundle and a polymer sheath surrounding the core, the sheath having a Melt Flow Index (MFI) of 47dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃). The MFI of the other polypropylene homo-or copolymer is lower than that of the sheath.

It is an object of the present invention to provide pellets of a glass fiber reinforced thermoplastic polymer composition which are suitable for the manufacture of extruded articles having good mechanical properties.

Accordingly, the present invention provides a pellet of a glass fiber reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament bundle comprising a longitudinally extending core and a polymer sheath tightly surrounding said core,

wherein the core comprises at least one continuous glass multifilament strand,

the polymer sheath is composed of a thermoplastic polymer composition comprising a polyolefin and having a melt flow index of at least 1.0dg/min and less than 20dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃),

wherein the length of the glass filaments in the pellet is substantially equal to the length of the pellet and is 10-55mm, preferably 10-40mm, more preferably 10-30mm, most preferably 10-20mm.

The present invention further provides a process for preparing pellets of a glass fiber reinforced thermoplastic polymer composition, the pellets comprising a sheathed continuous multifilament bundle comprising a longitudinally extending core and a polymer sheath tightly surrounding said core, the process comprising the steps of:

a) From a package of at least one continuous glass multifilament strand,

b) Applying a polymeric sheath comprising a thermoplastic polymer composition of polyolefin to the circumference of the at least one continuous glass multifilament bundle to form a sheathed continuous multifilament bundle, wherein the thermoplastic polymer composition has a melt flow index of at least 1.0dg/min and less than 20dg/min, measured according to ISO 1133-1:2011 (2.16 kg/230 ℃), and

c) Cutting the continuous glass multifilament bundle of the sheath to obtain pellets,

wherein the length of the glass filaments in the pellet is substantially equal to the pellet length and is 10-55mm, preferably 10-40mm, more preferably 10-30mm, most preferably 10-20mm.

Steps a) -b) are described in detail in WO 2009/080281A1, which is incorporated herein by reference.

The invention further provides a process for preparing an extruded article by melting and extruding the pellets according to the invention to obtain an extruded article.

The invention further provides an extruded article comprising the pellets according to the invention or manufactured by melting and extruding the pellets according to the invention.

The inventors have surprisingly found that pellets according to the invention can be used for manufacturing extruded articles with good mechanical properties. The relatively low MFI of the thermoplastic polymer composition comprising the polymer sheath enables the preparation of extruded articles in a stable manner. The length of the glass filaments in the pellets is substantially equal to the length of the pellets so that the extruded article has good mechanical properties.

Surprisingly, it has been found that the relatively low MFI of the thermoplastic polymer composition constituting the polymer sheath results in extruded articles having mechanical properties superior to those produced by extrusion with a mixture of the following pellets: the pellets have a polymer sheath made with a composition having a higher MFI and another polymer having a lower MFI, such as those disclosed in WO 2009/054716. While not wishing to be bound by any theory, this may be due to the less severe conditions required to melt and extrude the pellets according to the invention, which results in less glass strand breakage.

Pellet material

The pellets according to the invention comprise or consist of a sheathed continuous multifilament bundle comprising or consisting of a core and a polymer sheath. The pellets are generally cylindrical. The core is generally cylindrical and comprises at least one continuous glass multifilament strand comprising glass filaments. The core is tightly surrounded around its circumference by a polymeric sheath, which is generally tubular and consists of a thermoplastic polymer composition. The length of the glass filaments is substantially equal to the axial length of the pellets.

The core contains substantially no raw material for the sheath. The sheath is substantially free of glass filaments. Such pellet structures may be obtained by wire coating methods as disclosed in, for example, WO 2009/080281 and differ from pellet structures obtained via typical pultrusion type methods as disclosed in, for example, US 6,291,064.

Preferably, the polymer sheath is substantially free of glass filaments, meaning that it comprises less than 2wt% glass filaments based on the total weight of the polymer sheath.

Preferably, the radius of the core is 800-4000 microns and/or the thickness of the polymer sheath is 500-1500 microns.

Preferably, the core comprises 35-60% of the cross-sectional area of the pellet and the sheath comprises 40-65% of the cross-sectional area of the pellet.

Preferably, the amount of the continuous multifilament strand is 20 to 70wt%, such as 20 to 35wt%,35 to 50wt%, or 50 to 70wt%, relative to the continuous multifilament strand of the sheath. Preferably, the amount of the thermoplastic composition is 30 to 80wt%, such as 30 to 50wt%,50 to 65wt%, or 65 to 80wt%, relative to the continuous multifilament bundle of the sheath. Preferably, the total amount of the continuous multifilament strand and the thermoplastic composition is 100wt% relative to the sheathed continuous multifilament strand.

The pellets may generally have a length of from 10 to 55mm, preferably from 10 to 40mm, more preferably from 10 to 30mm, most preferably from 10 to 20mm. The length of the glass fibers is substantially the same as the length of the pellets. The length of the glass filaments may for example be 90-110% of the length of the pellets.

Polymer sheath

The sheath tightly surrounds the core. As used herein, the term tightly surrounding is understood to mean that the polymeric sheath is in substantially complete contact with the core. In other words, the sheath is applied to the core in such a way that there is no intentional gap left between the inner surface of the sheath and the core containing the impregnated continuous multifilament bundle. However, those skilled in the art will appreciate that some small gap may be formed between the polymer sheath and the core as a result of process variations.

The polymeric sheath is comprised of a thermoplastic polymer composition.

Thermoplastic polymers in thermoplastic polymer compositions of polymer sheath

The thermoplastic polymer composition comprises a polyolefin.

Preferably, the thermoplastic polymer composition comprises at least 80wt% polyolefin, such as at least 90wt%, at least 93wt%, at least 95wt%, at least 97wt%, at least 98wt%, or at least 99wt% polyolefin, based on the thermoplastic polymer composition. In a specific embodiment, the thermoplastic polymer composition consists of a polyolefin.

The polyolefin is preferably selected from the group consisting of propylene-based polymers (polypropylene), elastomers of ethylene and alpha-olefin comonomers having 4 to 8 carbon atoms, and any mixtures thereof.

Preferably, the polyolefin comprises a propylene-based polymer. Preferably, the thermoplastic polymer composition comprises at least 80wt% propylene-based polymer, such as at least 90wt%, at least 93wt%, at least 95wt%, at least 97wt%, at least 98wt%, or at least 99wt% propylene-based polymer, based on the thermoplastic polymer composition. In a specific embodiment, the thermoplastic polymer composition consists of a propylene-based polymer.

Preferably, the propylene-based polymer is selected from at least one of propylene homopolymers, propylene random copolymers and heterophasic propylene copolymers and mixtures thereof, preferably wherein the polyolefin comprises a propylene random copolymer; propylene homopolymers and heterophasic propylene copolymers; or propylene homopolymers and propylene random copolymers.

The propylene homopolymer may be obtained by polymerizing propylene under suitable polymerization conditions. Propylene copolymers may be obtained by copolymerizing propylene and one or more other alpha-olefins, preferably ethylene, under suitable polymerization conditions. The preparation of propylene homopolymers and copolymers is described, for example, in Moore, E.P. (1996) Polypropylene handbook, polymerization, characacterization, properties, processing, applications, hanser publications: in new york.

The random propylene copolymer may comprise ethylene and/or an alpha-olefin selected from alpha-olefins having 4 to 10 carbon atoms as comonomer, preferably ethylene, 1-butene, 1-hexene or any mixture thereof. The amount of comonomer is preferably up to 10 wt.%, based on the random propylene copolymer, for example from 2 to 7 wt.%, based on the random propylene copolymer.

The polypropylene may be produced by any known polymerization technique and using any known polymerization catalyst system. As the technique, slurry polymerization, solution polymerization or gas phase polymerization may be mentioned; as catalyst systems, ziegler-Natta, metallocene or single-site catalyst systems may be mentioned. All of which are known per se in the art.

Heterophasic propylene copolymers are typically prepared in one or more reactors by polymerizing propylene in the presence of a catalyst followed by polymerizing an ethylene-alpha-olefin mixture. The polymeric material formed is heterogeneous, but the specific morphology generally depends on the preparation method and the monomer ratio used.

The heterophasic propylene copolymer can be produced using any conventional technique known to the person skilled in the art, for example multi-stage polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combination thereof. Any conventional catalyst system may be used, such as ziegler-natta or metallocene. Such techniques and catalysts are described, for example, in WO 06/010414; polypropylene and other Polyolefins, ser van der Ven, studies in Polymer Science, elsevier 1990; WO 06/010414,US 4399054 and US 4472524.

Preferably, a Ziegler-Natta catalyst is used to prepare the heterophasic propylene copolymer.

The heterophasic propylene copolymer can be prepared by a process comprising:

-polymerizing propylene and optionally ethylene and/or alpha-olefins in the presence of a catalyst system to obtain a propylene-based matrix, and

-subsequently polymerizing ethylene and alpha-olefins in the propylene-based matrix in the presence of a catalyst system to obtain a dispersed ethylene-alpha-olefin copolymer. These steps are preferably carried out in different reactors. The catalyst systems used in the first and second steps may be different or the same.

The heterophasic propylene copolymer of the composition of the present invention consists of a propylene-based matrix and a dispersed ethylene-alpha-olefin copolymer. The propylene-based matrix typically forms a continuous phase in the heterophasic propylene copolymer. The amounts of propylene-based matrix and dispersed ethylene-alpha-olefin copolymer may be varied by methods well known in the art ¹³ C-NMR.

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

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, preferably ethylene.

Preferably, the propylene-based matrix consists of propylene homopolymers.

The propylene-based matrix may be present, for example, in an amount of 50 to 95 wt.%, based on the total heterophasic propylene copolymer, for example, the propylene-based matrix is present in an amount of 60 to 85 wt.%.

The amount of ethylene monomer units in the ethylene-alpha-olefin copolymer may be, for example, 20 to 65wt%. The amount of ethylene monomer units in the dispersed ethylene-alpha-olefin copolymer in the heterophasic propylene copolymer may sometimes be referred to herein as RCC2.

The alpha-olefin in the ethylene-alpha-olefin copolymer is preferably selected from alpha-olefins having 3 to 8 carbon atoms. Examples of suitable alpha-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 consisting of α -olefins having from 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.

The dispersed ethylene-alpha-olefin copolymer is present in an amount of 50 to 5wt%. Preferably, the dispersed ethylene-alpha-olefin copolymer is present in an amount of 40 to 15wt% based on the total heterophasic propylene copolymer.

In the heterophasic propylene copolymer of the composition of the present invention, the sum of the total weight of the matrix of propylene and the total weight of the dispersed ethylene-alpha-olefin copolymer is 100wt% of the heterophasic propylene copolymer.

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

In some preferred embodiments, the polyolefin in the thermoplastic polymer composition is a mixture of propylene homopolymers and heterophasic propylene copolymers.

Additives in thermoplastic polymer compositions of polymer sheaths

The thermoplastic polymer composition of the polymer sheath may contain other commonly used additives such as nucleating and clarifying agents, stabilizers, fillers, plasticizers, antioxidants, lubricants, antistatic agents, scratch-resistant agents, impact modifiers, acid scavengers, recycling additives, coupling agents, antimicrobial agents, antifogging agents, slip additives, antiblocking additives, polymer processing aids, flame retardants, colorants, and the like. Such additives are well known in the art. Those skilled in the art know how to select the type and amount of additives so that they do not adversely affect the target properties. The amount of additive may be, for example, 0.1 to 5.0wt% of the thermoplastic polymer composition. The amount of additive may be, for example, from 0.1 to 50wt% of the thermoplastic polymer composition.

In some preferred embodiments, the additive in the thermoplastic polymer composition of the polymer sheath comprises a flame retardant. The flame retardant may comprise an organic flame retardant and/or an inorganic flame retardant.

The organic flame retardant preferably comprises at least one phosphate selected from the group consisting of: melamine phosphate, melamine polyphosphate, melamine pyrophosphate, piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate, 2-methylpiperazine monophosphate, tricresyl phosphate, alkyl phosphate, haloalkyl phosphate, tetraphenyl pyrophosphate, poly (2-hydroxy-propenepentaerythritol diphosphate) and poly (2, 2-dimethylpropnepentaerythritol biphosphonate).

The organic flame retardant preferably comprises ammonium polyphosphate. In some preferred embodiments, the organic flame retardant comprises ammonium polyphosphate and at least one of the phosphate esters described above.

In some preferred embodiments, the organic flame retardant comprises ammonium polyphosphate and at least two of the above-described phosphates.

In some preferred embodiments, the organic flame retardant comprises ammonium polyphosphate, melamine polyphosphate, and piperazine phosphate.

In some preferred embodiments, the organic flame retardant comprises melamine phosphate and piperazine pyrophosphate.

The inorganic flame retardant may comprise, for example, zinc oxide.

In some preferred embodiments, the flame retardant may be particles comprising an organic flame retardant and zinc oxide. Preferably, the amount of zinc oxide relative to the particles is 1-10wt%.

In some preferred embodiments, the organic flame retardant comprises an aromatic phosphate ester.

In some preferred embodiments, the amount of the flame retardant, particularly the organic flame retardant, relative to the thermoplastic polymer composition of the polymer sheath is 0.1 to 50wt%, such as at least 1.0wt%, at least 5.0wt%, at least 10wt%, at least 20wt%, at least 30wt%, and/or up to 45wt%, or up to 40wt%.

The flame retardants described above, particularly the phosphate esters, can be used as part of the intumescent flame retardant composition. The intumescent flame retardant composition may contain different components to produce a coating that externally cokes when exposed to flame and/or high heat. The thermoplastic polymer composition comprising the intumescent flame retardant comprises a carbon source and the intumescent flame retardant composition may comprise a film-forming binder, an acid source, and a blowing agent. The carbon source may be an organic material that decomposes into char consisting essentially of carbon when exposed to fire or heat. The carbon source may be a polyolefin in the thermoplastic polymer composition. In the presence of an acid source (which promotes char formation) and a blowing agent (which expands char), the carbon source, when exposed to fire or heat, produces an expanded, insulating cell structure that is several times thicker than the original thickness.

Preferably, the sum of polyolefin and additives in the thermoplastic polymer composition is 100wt% relative to the thermoplastic polymer composition.

MFI of thermoplastic polymer composition and polyolefin

The MFI of the thermoplastic polymer composition, measured according to ISO 1133-1:2011 (2.16 kg/230 ℃) is at least 1.0dg/min and less than 20dg/min, preferably from 5.0 to 19dg/min, more preferably from 6.0 to 18dg/min.

Preferably, the polyolefin in the thermoplastic polymer composition has an MFI of at least 1.0dg/min and less than 20dg/min, preferably from 5.0 to 19dg/min, more preferably from 6.0 to 18dg/min, as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

When the polyolefin is a mixture of polyolefins having different MFI, the MFI of the mixture can be calculated by the person skilled in the art based on the MFI of each polyolefin. In this case, the MFI of the one or more polyolefins may be at least 20dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

In some particularly preferred embodiments, the polyolefin in the thermoplastic polymer composition comprises, preferably consists of, a first polyolefin, preferably a first propylene-based polymer, having an MFI of at least 20dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃), and a second polyolefin, preferably a second propylene-based polymer, having an MFI of less than 20dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃). Preferably, the weight ratio of the propylene homopolymer to the heterophasic propylene copolymer is from 5:1 to 1:5, for example from 3:1 to 1:1.

In some particularly preferred embodiments, the polyolefin in the thermoplastic polymer composition comprises or consists of a propylene homopolymer having an MFI of 25 to 50dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃) and a heterophasic propylene copolymer having an MFI of 0.1 to 5.0dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃). Preferably, the weight ratio of the propylene homopolymer to the heterophasic propylene copolymer is from 3:1 to 1:1.

Core(s)

The core extends longitudinally. In the context of the present invention, "longitudinally extending" means "oriented in the direction of the long axis of the continuous multifilament bundle of the sheathing".

Core of sheathed continuous multifilament bundle

The core of the wrapped continuous multifilament bundle comprises one or more continuous multifilament bundles. Preferably, the one or more continuous multifilament bundles form at least 90wt%, more preferably at least 93wt%, even more preferably at least 95wt%, even more preferably at least 97wt%, even more preferably at least 98wt%, even more preferably at least 99wt% of the core. In a preferred embodiment, the core consists of one or more continuous multifilament bundles.

Glass fiber of sheathed continuous multifilament bundle core

The continuous multifilament bundle comprises glass filaments. The glass fibers are typically provided as a plurality of continuous, very long filaments, and may be in the form of bundles, rovings, or yarns. Filaments are single fibers of reinforcing material. The bundle is a plurality of bundled filaments. A yarn is an aggregate of bundles, such as bundles twisted together. Roving refers to an aggregate of bundles wound into a package.

For the purposes of the present invention, a glass multifilament bundle is defined as a plurality of bundled glass filaments.

Glass multifilament bundles and their preparation are known in the art.

The filament density of the continuous glass multifilament bundles may vary within wide limits. For example, the continuous glass multifilament strand may have at least 500, such as at least 1000 glass filaments/strand, and/or at most 10000, such as at most 5000g/1000m. Preferably, the amount of glass filaments/strands is 500-10000g/1000m glass filaments/strands.

The thickness of the glass filaments is preferably 5-50. Mu.m, more preferably 10-30. Mu.m, even more preferably 15-25. Mu.m. Typically the glass filaments are circular in cross-section, which means that the thickness defined above will represent the diameter. Glass filaments are generally circular in cross-section.

Preferably, the ratio (L/D ratio) of the length of the glass fibers to the diameter of the glass fibers in the pellets is 500 to 1000.

The length of the glass filaments is in principle not limited, as it is substantially equal to the length of the continuous multifilament bundle of the sheathing. However, for practical reasons of being able to handle the bundle, it is desirable to be able to cut the sheathed continuous multifilament bundle into shorter bundles. For example, the length of the continuous multifilament bundle of the sheath is at least 1m, such as at least 10m, such as at least 50m, such as at least 100m, such as at least 250m, such as at least 500m, and/or such as at most 25km, such as at most 10km.

Preferably, the continuous glass multifilament strand comprises at most 2wt%, preferably 0.10-1wt% of sizing agent based on the continuous glass multifilament strand. The amount of sizing agent can be determined using ISO 1887:2014.

The sizing composition is typically applied to the glass filaments prior to finishing the filaments into a continuous glass multifilament bundle. Suitable examples of sizing compositions include solvent-based compositions such as organic materials dissolved in aqueous solutions or dispersed in water and melt or radiation-curable based compositions. Preferably, the sizing composition is an aqueous sizing composition.

The aqueous sizing composition may comprise a coupling agent and other further components as described in the prior art, for example in document EP 1460166A1,EP 0206189A1 or US 4338233.

Coupling agents are commonly used to improve the adhesion between the matrix thermoplastic polymer and the fibrous reinforcement. Suitable examples of coupling agents for glass fibers known in the art include organofunctional silanes. More specifically, the coupling agent (which has been added to the sizing composition) is an aminosilane, such as aminomethyl-trimethoxysilane, N- (β -aminoethyl) - γ -aminopropyl-trimethoxysilane, γ -aminopropyl-trimethoxysilane γ -methylaminopropyl-trimethoxysilane, δ -aminobutyl-triethoxysilane, 1, 4-aminophenyl-trimethoxysilane. Preferably, the sizing composition comprises an aminosilane to obtain good adhesion to the thermoplastic matrix. The sizing composition may further comprise any other additional components known to those skilled in the art to be suitable for the composition. Suitable examples include, but are not limited to, lubricants (to prevent damage to the strands by grinding), antistatic agents, cross-linking agents, plasticizers, surfactants, nucleating agents, antioxidants, pigments, and mixtures thereof.

Typically, after the sizing composition is applied to the glass filaments, the filaments are finished into a continuous glass multifilament bundle and then wound onto a spool to form a package.

Preferably, the amount of glass filaments is 20 to 70wt%, e.g., 20 to 35wt%,35 to 50wt%, or 50 to 70wt%, relative to the continuous multifilament bundle of the sheath.

Coupling agent

The continuous multifilament bundle of the sheath may contain a coupling agent in the core as part of the sizing agent described above. Alternatively, the continuous multifilament bundle of the sheath may comprise a coupling agent in the thermoplastic composition of the sheath.

Suitable examples of coupling agents include those described above and functionalized polyolefins grafted with acid or anhydride functionality. The polyolefin is preferably polyethylene or polypropylene, more preferably polypropylene. The polypropylene may be a propylene homopolymer or a propylene copolymer. The propylene copolymer may be a propylene-alpha-olefin copolymer consisting of at least 70wt% propylene and at most 30wt% of an alpha-olefin, such as ethylene, for example at least 80wt% propylene and at most 20wt% of an alpha-olefin, for example at least 90wt% propylene and at most 10wt% of an alpha-olefin, based on the total weight of the propylene-based matrix. Preferably, the alpha-olefin in the propylene-alpha-olefin copolymer is selected from alpha-olefins having 2 or 4 to 10 carbon atoms, preferably ethylene. Examples of acid or anhydride functional groups include (meth) acrylic acid and maleic anhydride. One particularly suitable material is, for example, a maleic acid functionalized propylene homopolymer (such as Exxelor PO 1020, supplied by Exxon).

The amount of coupling agent may for example be 0.5 to 3.0wt%, preferably 1.0 to 2.0wt%, based on the sheathing continuous multifilament bundle.

Impregnating agent

Impregnating agents for glass fibre reinforced thermoplastic polymer compositions comprising sheathed continuous multifilament strands are known, as described in WO 2009080281.

Numerous methods of applying an impregnating agent to a continuous glass multifilament strand are known in the art. Application of the liquid impregnant may be performed using a die. Other suitable methods for applying the impregnating agent to the continuous multifilament bundles include applicators with belts, rollers, and hot-melt applicators. These methods are described, for example, in document EP 0921919B1,EP 0994978B1,EP 0397505B1,WO 2014/053590A1 and the documents cited therein. The method used is capable of applying a constant amount of impregnating agent to a continuous multifilament bundle.

It is known that the impregnant has at least two key functions, the first being to provide adequate dispersion of the glass fibers in the downstream conversion process and the second being to effectively couple the glass fibers to each other and to the sheath in the pellet.

First, if the dispersion of the glass fibers in the downstream process is insufficient, this will result in aggregation of the glass fibers in the final product, resulting in a poor visual appearance, so-called "white spots", and possibly even loss or reduction of mechanical properties.

Second, if the impregnant does not sufficiently couple the glass fibers to each other and to the sheath, the glass fibers may separate from the pellets after they are subjected to repeated mechanical loads. Such repeated mechanical loading may occur, for example, during transport of the pellets through a piping system, or through a vibratory conveyor, such as a vibratory conveyor belt. Additional repeated mechanical loading occurs when shaking, stirring a number of pellets or when the pellets are filled into a suitable transport container, such as an octagonal bin. In addition, the shipping container may also experience vibration during shipping, which may be another cause of glass strand separation from the pellets. The repeated mechanical loading is generally of a random nature. Of particular importance is the separation of glass fibers from the pellets during their transport through the piping system, as the separated filaments can cause clogging of the piping system and/or filters, valves, outlets, etc. used in the piping system. Such blockage can lead to plant downtime and possible loss of production capacity. The problem of glass fiber separation from the pellets is often referred to as the "free glass" problem.

In accordance with the present invention, it has surprisingly been found that the substantial absence of an impregnating agent results in better dispersion of the glass filaments and better mechanical properties of the extruded article made from the pellets. It has further surprisingly been found that the substantial absence of an impregnating agent enables a larger length of pellets to be used to obtain desirable mechanical properties of extruded articles made from the pellets.

Preferably, the continuous multifilament bundle of the sheath comprises polyethylene wax having a melting point of 50-100 ℃, a MW of 5-10kg/mol and a polydispersity index (MWD) of 5-10 in an amount of less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt%, relative to the continuous multifilament bundle of the sheath. An example of such a polyethylene wax is the commercially available Dicera 13082Paramelt, a highly branched polyethylene wax.

Preferably, the continuous multifilament bundle of the sheath comprises polyethylene wax having a MW of at most 10kg/mol in an amount of less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt%, relative to the continuous multifilament bundle of the sheath.

Preferably, the continuous multifilament bundle of the sheath comprises a polyethylene wax having a melting point at least 20 ℃ lower than the polyolefin in the thermoplastic composition and a viscosity of 2.5-100cS, measured by ASTM D3236-15 (conventional test method for apparent viscosity of hot melt adhesives and coatings, brookfield viscometer, model RVDV 2, #27 spindle, 5 r/min), of less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt%, relative to the continuous multifilament bundle of the sheath) at 160 ℃.

Preferably, the continuous multifilament bundle of the sheath comprises less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt% of a microcrystalline polyethylene wax having at least one of the following properties relative to the amount of continuous multifilament bundle of the sheath:

-a drop melting point of 60-90 ℃ as determined according to ASTM D127;

the congealing point is 55-90 ℃, determined according to astm d 938;

penetration at 25 ℃ is 7-40/10mm, determined according to ASTM D1321;

a viscosity at 100℃of 10-25 mPa.s, determined according to ASTM D445, and

the oil content is 0 to 5wt% based on the weight of the microcrystalline wax, determined according to ASTM D721.

Preferably, the core consists essentially of glass filaments and any coupling agent. Preferably, the glass filaments and the coupling agent are at least 99.50wt%, at least 99.60wt%, at least 99.70wt%, at least 99.80wt%, at least 99.90wt%, at least 99.95wt%, at least 99.99wt%, or 100.00wt%, relative to the total amount of the core.

Extrusion

The invention further provides a process for producing an extruded article by melting and extruding pellets according to the invention to obtain an extruded article.

Preferably, the extruded article is a hollow article or sheet.

Preferably, the thickness of the sheet is 1-10mm, preferably 2-8mm, more preferably 2.5-6mm. This thickness is suitable for any subsequent thermoforming step. The weight of the sheet may be 5-10kg.

Preferably, the extruded article is produced by melting and extruding pellets according to the invention without adding further polyolefin. The extruded article comprises a higher amount of glass filaments and thus better mechanical properties than if the extruded article was produced using an additional polyolefin in addition to pellets of the glass fiber reinforced thermoplastic polymer composition.

In other embodiments, pellets according to the invention are melted and extruded with an optional additional propylene-based polymer.

Thus, in another aspect, the present invention provides a composition made by melt mixing pellets according to the present invention and another propylene-based polymer.

Suitable examples of such propylene-based polymers are those described in relation to the thermoplastic polymer composition of the polymer sheath. Preferably, the further polyolefin has a melt flow index of less than 20dg/min, preferably at least 0.1dg/min and less than 20dg/min, more preferably from 0.2 to 10dg/min, more preferably from 0.3 to 5.0dg/min, more preferably from 0.4 to 3.0dg/min, more preferably from 0.5 to 2.0dg/min, more preferably from 0.5 to 1.8dg/min, as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃). The weight ratio of the pellets according to the invention to the optionally further propylene-based polymer may for example be from 1:1 to 100:0, for example from 10:1 to 1:10. Preferably, the mixture of the thermoplastic polymer composition of the polymer sheath of the pellet and the further propylene-based polymer has a melt flow index of at least 1.0dg/min and less than 20dg/min, preferably from 5.0 to 19dg/min, more preferably from 6.0 to 18dg/min, measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

Preferably, the extruded article has a relatively large average glass fiber length Lw, for example, 0.1-1.5mm. The average glass strand length may be determined as a weight average strand length using a sample taken from the extruded article.

For example, the article is a multi-wall article having a largest dimension of at most 425mm and a wall thickness of at most 3mm, wherein the thermoplastic polymer composition of the polymer sheath has a polymer melt flow index of 10-15dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

Thermoforming

The invention further provides a method of preparing a thermoformed article by thermoforming an extruded article according to the invention, wherein the extruded article is a sheet.

The method of making a thermoformed article may comprise a method of making an extruded article according to the present invention, wherein the extruded article is a sheet, and thermoforming the sheet to obtain a thermoformed article.

The thermoforming may be performed by known thermoforming methods such as vacuum forming, pressure forming, solid press forming, twin sheet forming and stamping forming. These processes are generally carried out by heating the sheet above its softening temperature in the plastic deformation range, for example using rollers, hot plates or indirect heating means, such as radiant electric heaters, and forcing the sheet to conform to the shape of the mould, for example sucking them onto the mould.

Thermoforming may be performed under pressure or under vacuum. The pressure should be sufficient to conform the sheet to the final shape. Thermoforming under pressure may be performed, for example, at a pressure of 0.1-10 KPa. Thermoforming under vacuum may be performed, for example, at a pressure of-1 to-100 KPa.

Thermoforming may be performed, for example, at temperatures of 100 ℃ to 270 ℃. The appropriate temperature may be selected depending on the thermoplastic polymer composition used to make the sheet to be subjected to thermoforming, e.g., depending on whether the composition contains a flame retardant. If the composition comprises a flame retardant, the temperature may be selected to prevent decomposition of the flame retardant, for example up to 240 ℃.

Preferably, the thermoformed article according to the invention is a battery housing or a part thereof, such as an electric car battery housing or a part thereof, such as a top cover of an electric car battery housing. The battery case according to the present invention advantageously has good mechanical properties and fire resistance, and can replace conventional battery cases made of metal.

Preferably, the thermoformed article according to the invention is a top cover of the article for covering a battery component in an automotive prime mover battery pack, wherein the top cover has an outer major surface and an inner major surface shaped to mate with the battery component.

The invention further relates to an article for covering a battery component in an automotive motive power battery pack, the article comprising a top cover having an outer major surface and an inner major surface, shaped to mate with the battery component, wherein the top cover is a thermoformed article according to the invention. In addition to the top cover, the article for covering the battery components in the automotive prime mover battery pack may further comprise a bottom cover, and may further comprise a thermal management system and a layer of insulating material. Such an article may have the structure shown in fig. 9 of WO 2021069115A1, which shows an article comprising a top cover 24, a thermal management system 25, a layer of insulating material 26 and a bottom cover 27, which is incorporated herein by reference. The top cover 24 in WO 2021069115A1 is injection molded, whereas in the article according to the invention for covering battery parts in an automotive motive cell pack, the top cover is a thermoformed article according to the invention.

The thermoformed articles according to the invention comprise glass fibers which obtain improved mechanical properties such as stiffness and impact resistance.

In some preferred embodiments of the thermoformed article according to the invention, the thermoplastic polymer composition of the polymer sheath further comprises a flame retardant, preferably comprising the phosphate ester described above. This further improves the fire performance. This can result in the formation of an external char coating upon exposure of the thermoformed article to flame and/or high heat, which protects the components underlying the thermoformed article.

The battery case or top cover according to the invention is produced by thermoforming an extruded sheet according to the invention. They have limited shape variation, are generally flat, and have a limited series of operations, so thermoforming is an ideal manufacturing technique. Furthermore, since the distribution of the glass fibers in the extruded sheet is uniform compared to, for example, injection molded articles, the distribution of the glass fibers in the battery case or top cover according to the present invention is uniform, which results in good mechanical properties and fire resistance.

It is to be noted that the invention relates to the subject matter defined in the independent claims alone or in combination with any possible combination of the features described herein, preferably in particular those combinations of features which are present in the claims. It will be understood that all combinations of features described herein in relation to the compositions according to the invention; all combinations of features relating to the method according to the invention, as well as all combinations of features relating to the composition according to the invention and features relating to the invention.

It is further noted that the term "comprising" does not exclude the presence of other elements. However, it is to be understood that the description of the product/composition comprising certain components also discloses a product/composition consisting of these components. An advantage of a product/composition composed of these components may be that it provides a simpler, more economical process for preparing the product/composition. Similarly, it is to be understood that the description of the method comprising certain steps also discloses a method consisting of these steps. The advantage of a process consisting of these steps may be that it provides a simpler, more economical process.

The invention will now be illustrated by, but not limited to, the following examples.

Examples

Material used

PP1：PP 595A, propylene homopolymer (melt flow index measured according to ISO1133 at 230 ℃ C./2.16 kg is 47dg/min, MW 165kg/mol, MWD 7.6).

PP2：PP 83MF10, a heterophasic propylene copolymer, consisting of a propylene homopolymer and a propylene-ethylene copolymer (melt flow index measured according to ISO1133 at 230 ℃/2.16kg is 1.8dg/min; ethylene content (Tc) in the heterophasic propylene copolymer is 13.9.+ -. 1.1wt%, MW is 422kg/mol, MWD is 7.4).

GF: the glass multifilament bundle, having a diameter D of 19 μm and a tex of 3000, contained 2% by mass of an aminosilane sizing agent.

LDPE：LDPE 1905U0Ultra Melt Strength (UMS) has a melt flow index of 5dg/min at 190℃and 2.16kg, as measured according to ISO 1133. Density according to ASTM D1505 is 920kg/m ³ 。

Impregnating agent: a highly branched polyethylene wax, density: 890-960kg/m ³ Dynamic viscosity at 100 ℃): 40-58 mPa.s (ASTM D3236), melting point: 65 ℃, MW:400kg/mol, MWD:6.8 (Dicera 13082 Paramelt).

Coupling agent: exxelor PO 1020 powder (PP-g-MA) from ExxonMobil: density: 900kg/m ³ Melting point: 162 ℃, 230 ℃ and MFR of 2.16 kg: 430g/10min (test method: ASTM D1238).

UV stabilizer: chimasorb 119FL, a Hindered Amine Light Stabilizer (HALS).

Heat stabilizer:b225, commercially available from BASF, is 50wt% tris (2, 4-di-t-butylphenyl) phosphite and 50wt% pentaerythritol tetrakis [3- [3, 5-di-t-butyl-4-hydroxyphenyl ]]Propionic acid esters]Is a blend of (a) and (b).

Here, MW is measured according to ASTM D6474-12.

Examples 1 to 2

Preparation of sheathed continuous multifilament bundles (wire coating)

The sheathed continuous multifilament bundles were prepared using a wire coating method with the components given in table 1, as detailed in the examples of WO 2009/080281 A1. After the wire coating process, the strands were cut into pellets having a length of 15 mm. In this pellet, the glass multifilament yarn was thus 15mm in length L and 19 μm in diameter D (L/D ratio 789).

For pellet B, the wire coating process was performed as follows:

unwinding from a package of continuous glass multifilament bundles containing at most 2 mass% of sizing composition,

applying 2.6wt% of an impregnating agent to the multifilament bundles to form impregnated continuous multifilament bundles;

applying a sheath of thermoplastic polymer composition previously mixed in a twin-screw extruder around the impregnated continuous multifilament bundle to form a sheathed continuous multifilament bundle.

The wire coating process was the same for pellet a except that the step of applying the impregnating agent was not performed.

TABLE 1

	Ex A	Ex B
			PP1(MFI 47dg/min)	43.7	41.97
PP2(MFI 1.8dg/min)	24.07	23.5
			GF	30.17	30.17
Impregnating agent	0	2.6
			Coupling agent	1.8	1.5
UV stabilizer	0.06	0.06
			Heat stabilizer	0.2	0.2

			MFI (dg/min) of the composition	17.5	17.2

The amount units are wt% relative to the total composition of the pellets.

* The melt flow index of the thermoplastic polymer composition used to prepare the sheath was determined at 230℃C/2.16 kg according to ISO 1133-1:2011.

Extrusion

For examples 1 and 2, respectively, pellets obtained by examples a and B were fed into the hopper of a twin screw extruder (co-rotating, L/d=32, d=44 mm) where polymer melting and dispersion and glass fiber breakage occurred by a shear of 100-10001/s and a temperature profile of 60 ℃ (pellet feed), 4D zone 210 ℃,12D zone 235 ℃,10D/210 ℃ and die zone temperature 190 ℃. The molten composition is transferred to a mold where it is shaped and pulled from the mold with a puller.

Extrusion can be carried out without sagging. The final product is obtained by cooling. The throughput of the extruder was 80kg/h.

Comparative test 3

Pellets of long glass fiber reinforced polypropylene composition (STAMAX 60YM240 with a sheath made of thermoplastic polymer composition with an MFI of 47dg/min measured according to ISO 1133 at 230 ℃/2.16 kg) were melt blended and subjected to the same extrusion step as in example 1 together with PP2 and additives. The composition of the extruded article is shown in table 2.

TABLE 2

	Ex B
		STAMAX 60YM240 sheath (MFI 47 dg/min)	41.97
PP2(MFI 1.8dg/min)	23.5
		GF (STAMAX 60YM240 core)	30.17
Impregnating agent	2.6
		Coupling agent	1.5
UV stabilizer	0.06
		Heat stabilizer	0.2

		MFI (dg/min) of the composition	17.2

The amount units are wt% relative to the total composition of the pellets.

* The melt flow index of the mixture of polymer composition of the sheath and PP2 is calculated based on the MFI of the individual components measured according to ISO1133 at 230 ℃/2.16 kg.

Extrusion can be carried out without sagging. The final product is obtained by cooling.

Performance of

For the extruded articles of examples 1, 2 and comparative experiment 3, the following properties were measured by cutting samples from the extruded articles in the extrusion direction. The results are given in table 2.

Elastic modulus according to ISO 527-2/1B.

Tensile strength according to ISO 527-2/1B.

In addition, the level of dispersion of the glass filaments in the extruded article was determined. Samples were cut from multiple locations on the extruded article. The level of dispersion was determined using microcomputer tomography (μct) and X-ray image analysis.

TABLE 2

	Ex1	Ex2	CEx3
				Extruded compositions	Low MFI pellets	Low MFI pellets	High MFI pellets and low MFI PP
Wax	Whether or not	Is that	Is that
				GF dispersion	++	++	+
Modulus of elasticity 0 [%]	1.34	1.24	1
				Tensile strength 0 [%]	1.34	1.24	1
Modulus of elasticity 45 [%]	1.78		1
				Tensile strength 45 [% ]	1.60		1

The addition of low MFI polypropylene enabled extrusion, but glass fiber dispersion was not ideal (comparative test 3). Pellets with a sheath made with a low MFI composition can be extruded into articles with better glass fiber dispersion and better mechanical properties (examples 1 and 2).

The absence of wax in the pellets gave better mechanical properties (example 1 compared to example 2). This is surprising because the impregnant is able to effectively couple glass fibers to each other and to the polypropylene sheath in the pellets, and provides sufficient dispersion of the glass fibers in the downstream conversion process is a well known effect.

Comparative test 4

Comparative run 3 was repeated except that 20wt% of PP2 was replaced with the same amount of LDPE.

Extrusion can be performed without sagging, but the extrusion capacity is reduced compared to examples 1, 2 and comparative experiment 3. The final product is obtained by cooling.

The mechanical properties of the extruded product were not higher than in comparative test 3, and GF dispersion was poor, which caused white spots.

Comparative test 5

The long glass fiber reinforced polypropylene composition pellets (STAMAX 30YM240, 40YM240 and 60YM 240) were subjected to the same extrusion step as in example 1. Extrusion is not possible due to sagging.

Comparative test 6

Pellets of a glass fiber-reinforced polypropylene composition (Verton MV 006S) produced by the ironing process were subjected to the same extrusion step as in example 1. Extrusion is not possible due to sagging.

It is understood that it is not possible to extrude pellets containing per se a composition having a high MFI (comparative test 5 and comparative test 6), whereas pellets according to the invention can be extruded (example 1 and example 2).

Claims

1. Pellets of a glass fiber reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament bundle comprising a longitudinally extending core and a polymer sheath tightly surrounding the core,

wherein the core comprises at least one continuous glass multifilament strand,

the polymer sheath is composed of a thermoplastic polymer composition comprising a polyolefin and having a melt flow index of at least 1.0dg/min and less than 20dg/min, preferably from 5.0 to 19dg/min, more preferably from 6.0 to 18dg/min, measured in accordance with ISO 1133-1:2011 (2.16 kg/230 ℃),

2. The pellet of claim 1, wherein the continuous multifilament bundle of the sheath comprises polyethylene wax having a melting point of 50-100 ℃, a MW of 5-10kg/mol and a MWD of 5-10 in an amount of less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt% relative to the continuous multifilament bundle of the sheath.

3. The pellet of any of the preceding claims, wherein the continuous multifilament bundle of the sheath comprises polyethylene wax having a MW of up to 10kg/mol in an amount of less than 0.50wt%, preferably less than 0.40wt%, less than 0.30wt%, less than 0.20wt%, less than 0.10wt%, less than 0.05wt%, less than 0.01wt%, or 0.00wt% relative to the continuous multifilament bundle of the sheath.

4. The pellet of any of the preceding claims, wherein the polyolefin comprises an elastomer of propylene-based polymer and/or ethylene and an alpha-olefin comonomer having 4 to 8 carbon atoms, wherein the propylene-based polymer is at least one selected from the group consisting of propylene homopolymers, propylene random copolymers and heterophasic propylene copolymers and mixtures thereof.

5. The pellet of any of the preceding claims, wherein the polyolefin comprises or consists of a propylene homopolymer having a melt flow index of 25-50dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃) and a heterophasic propylene copolymer having a melt flow index of 0.1-5.0dg/min as measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

6. The pellet of any of the preceding claims, wherein the amount of glass filaments is 20-70wt% relative to the continuous multifilament bundle of the sheath.

7. A process for preparing pellets of a glass fiber reinforced thermoplastic polymer composition, the pellets comprising a sheathed continuous multifilament bundle comprising a longitudinally extending core and a polymer sheath tightly surrounding the core, the process comprising the successive steps of:

b) Applying a polymeric sheath comprising a thermoplastic polymer composition of a polyolefin to the circumference of the at least one continuous glass multifilament bundle to form a sheathed continuous multifilament bundle, wherein the thermoplastic polymer composition has a melt flow index of at least 1.0dg/min and less than 20dg/min, preferably from 5.0 to 19dg/min, more preferably from 6.0 to 18dg/min, measured according to ISO 1133-1:2011 (2.16 kg/230 ℃), and

8. A process for preparing an extruded article by melting and extruding pellets according to any of claims 1-6.

9. The method of claim 8, wherein the article is a hollow article or sheet.

10. The method according to any one of claims 8 to 9, wherein the amount of glass filaments is 20 to 70wt% relative to the extruded article.

11. The process according to any one of claims 8-10, wherein the extruded article is produced by melting and extruding the pellets according to any one of claims 1-6 without adding further polyolefin.

12. The method of any one of claims 8-10, wherein the extruded article is produced by melting and extruding together the pellets of any one of claims 1-6 and an additional propylene-based polymer.

13. The process according to claim 12, wherein the further propylene-based polymer has a melt flow index of less than 20dg/min, preferably of at least 0.1dg/min and less than 20dg/min, more preferably of from 0.2 to 10dg/min, more preferably of from 0.3 to 5.0dg/min, more preferably of from 0.4 to 3.0dg/min, more preferably of from 0.5 to 2.0dg/min, more preferably of from 0.5 to 1.8dg/min, measured according to ISO 1133-1:2011 (2.16 kg/230 ℃).

14. A method of preparing a thermoformed article comprising obtaining an extruded article according to the method of any one of claims 8-13, wherein the extruded article is a sheet and thermoforming the sheet.

15. The method of claim 14, wherein the thermoformed article is a top cover in an article for covering a battery component in an automotive prime mover battery pack, wherein the top cover has an outer major surface and an inner major surface that is shaped to mate with the battery component.

16. Extruded article comprising the pellet according to any one of claims 1-6 or manufactured by melting and extruding the pellet according to any one of claims 1-6.

17. The extruded article of claim 16, wherein the article is a multi-wall article having a largest dimension of at most 425mm and a wall thickness of at most 3mm, wherein the thermoplastic polymer composition of the polymer sheath has a melt flow index of 10-15dg/min as measured according to ISO1133-1:2011 (2.16 kg/230 ℃).

18. A thermoformed article made by thermoforming the extruded article of claim 16, preferably wherein the thermoforming is selected from the group consisting of vacuum forming, pressure forming, solid press forming, twin sheet forming, and stamping forming.

19. The thermoformed article of claim 18, wherein the thermoformed article is a top cover in an article for covering a battery component in an automotive prime mover battery pack, wherein the top cover has an outer major surface and an inner major surface that are shaped to mate with the battery component.