Glass fiber-reinforced thermoplastic polymer composition

Abstract

The invention relates to a glass fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand comprising a core that extends in the longitudinal direction and a polymer sheath which intimately surrounds said core, wherein the core comprises a coated an impregnated continuous multifilament strand comprising at least one continuous glass multifilament strand, wherein the at least one continuous glass multifilament strand is impregnated coated with a coating composition an impregnating agent comprising a polypropylene, wherein the impregnating agent has a melt flow index as measured according to ISO1133-1:2011 (2.16kg / 230°C) of at least 3000 dg / min and a melting point of at least 140 ⁰C as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 ⁰C / min using 5 mg sample and the amount of the polypropylene in the impregnating agent is at least 80% with respect to the impregnating agenthaving a melt flow index as measured according to ISO1133-1:2011 (2.16kg / 230°C) of at least 3000 dg / min and compising a polypropylene, wherein the polymer sheath consists of a thermoplastic polymer composition comprising a thermoplastic polymer.

Description

[0001] GLASS FIBER-REINFORCED THERMOPLASTIC POLYMER COMPOSITION

[0002] The present invention relates to a glass fiber-reinforced thermoplastic polymer composition and a process for producing such composition.

[0003] A glass fiber-reinforced thermoplastic polymer composition can be made by a process comprising subsequent steps of unwinding from a package of a continuous glass multifilament strand and applying a sheath of polypropylene around said multifilament strand to form a sheathed continuous multifilament strand.

[0004] Such process is known from International application W02009 / 080281. This published patent application discloses a process for producing a long glass fiber-reinforced thermoplastic polymer composition, which comprises the subsequent steps of i) unwinding from a package of at least one continuous glass multifilament strand, ii) applying an impregnating agent to said at least one continuous glass multifilament strand to form an impregnated continuous multifilament strand, and iii) applying a sheath of thermoplastic polymer around the impregnated continuous multifilament strand to form a sheathed continuous multifilament strand. The impregnating agent is non-volatile, has a melting point of at least 20 °C below the melting point of the thermoplastic matrix, has a viscosity of from 2.5 to 100 cS at application temperature, and is compatible with the thermoplastic polymer to be reinforced.

[0005] It is desirable that a moulded article made from a glass fiber-reinforced thermoplastic polymer composition has good mechanical properties such as tensile and flexural properties. It is also desirable that the article has good smell properties. Good visual appearance is also desirable such as an appearance with less white spots. White spots may occur due to an insufficient dispersion of the fibers in the article.

[0006] It is an objective of the present invention to provide a glass fiber-reinforced thermoplastic polymer composition in which the above-mentioned and / or other needs are met. Accordingly, the invention provides a glass fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand comprising a core that extends in the longitudinal direction and a polymer sheath which intimately surrounds said core, wherein the core comprises an impregnated continuous multifilament strand comprising at least one continuous glass multifilament strand, wherein the at least one continuous glass multifilament strand is impregnated with an impregnating agent comprising a polypropylene, wherein the polypropylene in the impregnating agent has an Mw of at most 5.5 kg / mol and a melting point of at least 140 °C as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample and the amount of the polypropylene in the impregnating agent is at least 80% with respect to the impregnating agent, wherein the polymer sheath consists of a thermoplastic polymer composition comprising a thermoplastic polymer.

[0007] The invention further provides a process for the production of the glass fiber-reinforced thermoplastic polymer composition according to the invention, comprising the sequential steps of: a) unwinding from a package of the at least one continuous glass multifilament strand, b) applying the impregnating agent to the at least one continuous glass multifilament strand to form the impregnated continuous multifilament strandand c) applying the sheath of the thermoplastic polymer composition around the impregnated continuous multifilament strandto form the sheathed continuous multifilament strand and optionally d) cutting the sheathed continuous glass multifilament strand into pellets.

[0008] Details relevant to steps a) and c) are described in W02009 / 080281 A1 , which document is hereby incorporated by reference.

[0009] The process for the production of the glass fiber-reinforced thermoplastic polymer composition according to the invention may further comprise the step of d) cutting the sheathed continuous glass multifilament strand into pellets. A moulded article made from the glass fiber-reinforced thermoplastic polymer composition according to the invention has good tensile and flexural properties.

[0010] Unlike applying known impregnating agents described e.g. in W02009 / 080281A1 which have a melting point of at least 20 °C below the melting point of the thermoplastic polymer of the sheath, an impregnating agent comprising a polypropylene is applied according to the invention which has a melting point similar to the thermoplastic polymer of the sheath. The impregnating agent is applied in a molten state. The step of applying the impregnating agent and the step of applying the sheath are performed directly after each other, meaning that the applied impregnating agent still has substantially the same of similar temperature upon application of the sheath.

[0011] Sheathed continuous multifilament strand

[0012] The glass fiber-reinforced thermoplastic polymer composition according to the invention, which may be in the form of pellets, comprises or consists of the sheathed continuous multifilament strand. The sheathed continuous multifilament strand comprises or consists of a core and a polymer sheath. The core has a generally cylindrical shape and comprises an impregnated continuous multifilament strand comprising glass filaments. The core is intimately surrounded around its circumference by a polymer sheath having a generally tubular shape and consisting of a thermoplastic polymer composition. The glass filaments have a length substantially equal to the axial length of the pellet.

[0013] The core does not substantially contain the material of the sheath. The sheath is substantially free of the glass filaments. Such a pellet structure is obtainable by a wirecoating process such as for example disclosed in WO 2009 / 080281 and is distinct from the pellet structure that is obtained via the typical pultrusion type of processes such as disclosed in US 6,291 ,064.

[0014] Preferably, the polymer sheath is substantially free of the glass filaments, meaning it comprises less than 2 wt% of the glass filaments based on the total weight of the polymer sheath. Preferably, the radius of the core is between 800 and 4000 micrometer and / or the thickness of the polymer sheath is between 500 and 1500 micrometer.

[0015] Preferably, the core comprises between 35 and 60 % of the cross section area of the pellet and the sheath comprises between 40 and 65 % of the cross section area of the pellet.

[0016] In some embodiments, the core comprises between 3 and 35 % of the cross section area of the pellet and the sheath comprises between 65 and 97 % of the cross section area of the pellet. In some embodiments, the core comprises between 35 and 60 % of the cross section area of the pellet and the sheath comprises between 40 and 65 % of the cross section area of the pellet.

[0017] Preferably, the amount of the impregnated continuous multifilament strand is 10 to 80 wt%, for example 10 to 50 wt% (for example 25 to 45 wt%) or 50 to 80 wt% (for example 60 to 75 wt%), with respect to the sheathed continuous multifilament strand. Preferably, the amount of the second thermoplastic composition is 20 to 90 wt%, for example 20 to 50 wt% (for example 25 to 40 wt%) or 50 to 90 wt% (for example 55 to 75 wt%), with respect to the sheathed continuous multifilament strand. Preferably, the total amount of the impregnated continuous multifilament strand and the second thermoplastic composition is 100 wt% with respect to the sheathed continuous multifilament strand.

[0018] Polymer sheath

[0019] The sheath intimately surrounds the core. The term intimately surrounding as used herein is to be understood as meaning that the polymer sheath substantially entirely contacts the core. Said in another way the sheath is applied in such a manner onto the core that there is no deliberate gap between an inner surface of the sheath and the core containing the impregnated continuous multifilament strands. A skilled person will nevertheless understand that a certain small gap between the polymer sheath and the core may be formed as a result of process variations.

[0020] The polymer sheath consists of a thermoplastic polymer composition. sheath

[0021] The thermoplastic polymer composition comprises a thermoplastic polymer. Preferably, the thermoplastic polymer composition consists of the thermoplastic polymer and additives described below. of polymer sheath

[0022] The amount of the thermoplastic polymer with respect to the thermoplastic polymer composition may be at least 50 wt%, for example 50 to 99.9 wt%, 75 to 99.9 wt% or 95 to 99 wt%.

[0023] Suitable examples of thermoplastic polymers include but are not limited to polyamide, such as polyamide 6, polyamide, 66 or polyamide 46; polyolefins, for example polypropylenes and polyethylenes; polyesters, such as polyethylene terephthalate, polybutylene terephthalate; polycarbonates; polyphenylene sulphide; polyurethanes and and mixtures thereof.

[0024] The thermoplastic polymer is preferably a polyolefin, more preferably a polyolefin chosen from the group of polypropylenes or elastomers of ethylene and a-olefin comonomer having 4 to 8 carbon atoms, and any mixtures thereof.

[0025] In one embodiment, preferably the thermoplastic polymer composition comprises at least 80wt% of the thermoplastic polymer, for example at least 90wt%, at least 93wt%, at least 95wt%, at least 97wt% at least 98wt% or at least 99wt% of the thermoplastic polymer based on the thermoplastic polymer composition. In a special embodiment, the thermoplastic polymer composition consists of the thermoplastic polymer. In another embodiment, the thermoplastic polymer composition comprises at least 60wt%, for example at least 70wt%, for example at least 75wt% and / or at most 99wt%, for example at most 95wt%, for example at most 90wt% of the thermoplastic polymer.

[0026] Preferably, the thermoplastic polymer has a melt flow index in the range from 20 to 150 dg / min, for example in the range from 30 to 140 dg / min as measured according to ISO1133-1 :2011 (2.16kg / 230°C). Preferably, the thermoplastic polymer has a melt flow index in the range from 50 to 130 dg / min as measured according to ISO1133-1 :2011 (2.16kg / 230°C). This leads to good mechanical properties of the obtained composition.

[0027] The polypropylene may for example be a propylene homopolymer or a random propylene copolymer or a heterophasic propylene copolymer.

[0028] A propylene homopolymer can be obtained by polymerizing propylene under suitable polymerization conditions. A propylene copolymer can be obtained by copolymerizing propylene and one or more other a-olefins, preferably ethylene, under suitable polymerization conditions. The preparation of propylene homopolymers and copolymers is, for example, described in Moore, E. P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.

[0029] The random propylene copolymer may comprise as the comonomer ethylene or an a- olefin chosen from the group of a-olefins having 4 to 10 C-atoms, preferably ethylene, 1 -butene, 1 -hexene or any mixtures thereof. The amount of the comonomer is preferably at most 10wt% based on the random propylene copolymer, for example in the range from 2-7wt% based on the random propylene copolymer.

[0030] Polypropylenes can be made by any known polymerization technique as well as with any known polymerization catalyst system. Regarding the techniques, reference can be given to slurry, solution or gas phase polymerizations; regarding the catalyst system reference can be given to Ziegler-Natta, metallocene or single-site catalyst systems. All are, in themselves, known in the art.

[0031] Heterophasic propylene copolymers are generally prepared in one or more reactors, by polymerization of propylene in the presence of a catalyst and subsequent polymerization of an ethylene-a-olefin mixture. The resulting polymeric materials are heterophasic, but the specific morphology usually depends on the preparation method and monomer ratios used.

[0032] The heterophasic propylene copolymers can be produced using any conventional technique known to the skilled person, for example multistage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combinations thereof. Any conventional catalyst systems, for example, Ziegler-Natta or metallocene may be used. Such techniques and catalysts are described, for example, in W006 / 010414; Polypropylene and other Polyolefins, by Ser van der en, Studies in Polymer Science 7, Elsevier 1990; W006 / 010414, US4399054 and US4472524.

[0033] Preferably, the heterophasic propylene copolymer is made using Ziegler-Natta catalyst.

[0034] The heterophasic propylene copolymer may be prepared by a process comprising

[0035] - polymerizing propylene and optionally ethylene and / or a-olefin in the presence of a catalyst system to obtain the propylene-based matrix and

[0036] - subsequently polymerizing ethylene and a-olefin in the propylene-based matrix in the presence of a catalyst system to obtain the dispersed ethylene-a olefin copolymer. These steps are preferably performed in different reactors. The catalyst systems for the first step and for the second step may be different or same.

[0037] The heterophasic propylene copolymer of the composition of the invention consists of a propylene-based matrix and a dispersed ethylene-a-olefin copolymer. The propylene- based matrix typically forms the continuous phase in the heterophasic propylene copolymer. The amounts of the propylene-based matrix and the dispersed ethylene-a- olefin copolymer may be determined by13C-NMR, as well known in the art.

[0038] The propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 70 wt% of propylene monomer units and at most 30 wt% of comonomer units selected from ethylene monomer units and a-olefin monomer units having 4 to 10 carbon atoms, for example consisting of at least 80 wt% of propylene monomer units and at most 20 wt% of the comonomer units, at least 90 wt% of propylene monomer units and at most 10 wt% of the comonomer units or at least 95 wt% of propylene monomer units and at most 5 wt% of the comonomer units, based on the total weight of the propylene-based matrix.

[0039] Preferably, the comonomer in the propylene copolymer of the propylene-based matrix is selected from the group of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1- hexen, 1 -heptene and 1 -octene, and is preferably ethylene. Preferably, the propylene-based matrix consists of a propylene homopolymer.

[0040] The melt flow index (MFI) of the propylene-based matrix (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFIPP. may 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). The MFIPPmay be in the range of for example 0.1 to 50 dg / min, for example from 0.2 to 40 dg / min, for example 0.3 to 30 dg / min, for example 0.5 to 25 dg / min, for example from 1 to 20 dg / min, for example from 1 .5 to 10 dg / min, measured according to ISO1133 (2.16 kg / 230°C).

[0041] The propylene-based matrix may e.g. be present in an amount of 50 to 95wt%. Preferably, the propylene-based matrix is present in an amount of 60 to 85wt%, for example at least 65 wt% or at least 70 wt% and / or at most 78 wt%, based on the total heterophasic propylene copolymer.

[0042] The propylene-based matrix is preferably semi-crystalline, that is it is not 100% amorphous, nor is it 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, for example at least 50%, for example at least 60% crystalline and / or for example at most 80% crystalline, for example at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. For purpose of the invention, the degree of crystallinity of the propylene-based matrix is measured using differential scanning calorimetry (DSC) according to ISO11357-1 and ISO11357- 3 of 1997, using a scan rate of 10°C / min, a sample of 5mg and the second heating curve using as a theoretical standard for a 100% crystalline material 207.1 J / g.

[0043] Besides the propylene-based matrix, the heterophasic propylene copolymer also comprises a dispersed ethylene-a-olefin copolymer. The dispersed ethylene-a-olefin copolymer is also referred to herein as the ‘dispersed phase’. The dispersed phase is embedded in the heterophasic 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 may be determined by transmission electron microscopy (TEM). The amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RC.

[0044] The amount of ethylene monomer units in the ethylene-a-olefin copolymer may e.g. be 20 to 65 wt%. The amount of ethylene monomer units in the dispersed ethylene-a- olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RCC2.

[0045] The a-olefin in the ethylene-a-olefin copolymer is preferably chosen from the group of a- olefins having 3 to 8 carbon atoms. Examples of suitable a-olefins having 3 to 8 carbon atoms include but are not limited to propylene, 1 -butene, 1 -pentene, 4-methyl-1 -pentene, 1-hexen, 1 -heptene and 1 -octene. More preferably, the a-olefin in the ethylene-a-olefin copolymer is chosen from the group of a-olefins having 3 to 4 carbon atoms and any mixture thereof, more preferably the a-olefin is propylene, in which case the ethylene-a- olefin copolymer is ethylene-propylene copolymer.

[0046] The MFI of the dispersed ethylene a-olefin copolymer (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFIrubber, may 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 MFIrubber may be in the range for example from 0.001 to 30 dg / min, for example from 0.01 to 20 dg / min, for example 0.1 to 15 dg / min, for example 0.3 to 10 dg / min, for example from 0.7 to 5 dg / min, for example from 1 to 3 dg / min. MFIrubber is calculated according to the following formula: wherein

[0047] MFIheterophasic is the MFI (dg / min) of the heterophasic propylene copolymer measured according to ISO1133 (2.16kg / 230°C),

[0048] MFImatrix is the MFI (dg / min) of the propylene-based matrix measured according to ISO1133 (2.16kg / 230°C), matrix content is the fraction of the propylene-based matrix in the heterophasic propylene copolymer, rubber content is the fraction of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer. The sum of the matrix content and the rubber content is 1 . For the avoidance of any doubt, Log in the formula means log 10.

[0049] The dispersed ethylene-a-olefin copolymer is present in an amount of 50 to 5 wt% based on the total heterophasic propylene copolymer. Preferably, the dispersed ethylene-a- olefin copolymer is present in an amount of 40 to 15 wt%, for example in an amount of at least 22 wt% and / or for example in an amount of at most 35 wt% or at most 30 wt% based on the total heterophasic propylene copolymer.

[0050] In the heterophasic propylene copolymer in the composition of the invention, the sum of the total weight of the propylene-based matrix and the total weight of the dispersed ethylene-a-olefin copolymer is 100 wt% of the heterophasic propylene copolymer.

[0051] The a-olefin in the ethylene-a-olefin copolymer is preferably chosen from the group of a-olefins having 3 to 8 carbon atoms and any mixtures thereof, preferably the a-olefin in the ethylene-a-olefin copolymer is chosen from the group of a-olefins having 3 to 4 carbon atoms and any mixture thereof, more preferably the a-olefin is propylene, in which case the ethylene-a-olefin copolymer is ethylene-propylene copolymer.

[0052] Examples of suitable a-olefins having 3 to 8 carbon atoms, which may be employed as ethylene comonomers to form the ethylene a-olefin copolymer include but are not limited to propylene, 1 -butene, 1 -pentene, 4-methyl-1 -pentene, 1-hexen, 1 -heptene and 1 -octene.

[0053] The elastomer of ethylene and a-olefin comonomer having 4 to 8 carbon atoms may for example have a density in the range from 0.850 to 0.915 g / cm3. Such elastomers are sometimes also referred to as plastomers.

[0054] The a-olefin comonomer in the elastomer is preferably an acyclic monoolefin such as 1 -butene, 1 -pentene, 1 -hexene, 1 -octene, or 4-methylpentene.

[0055] Accordingly, the elastomer is preferably selected from the group consisting of ethylene-1 -butene copolymer , ethylene-1 -hexene copolymer, ethylene-1 -octene copolymer and mixtures thereof, more preferably wherein the elastomer is selected from ethylene-1 -octene copolymer. Most preferably, the elastomer is an ethylene-1 - octene copolymer.

[0056] Preferably, the density of the elastomer is at least 0.865 g / cm3and / or at most 0.910 g / cm3. 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 / cm3. More preferable the density of the elastomer is in the range from 0.88 up to an including 0.907 g / cm3, most preferably, the density of the elastomer is in the range from 0.90 up to and including 0.906 g / cm3.

[0057] Elastomers which are suitable for use in the current invention are commercially available for example under the trademark EXACT™ available from Exxon Chemical Company of Houston, Texas or under the trademark ENGAGE™ polymers, a line of metallocene catalyzed plastomers available from Dow Chemical Company of Midland, Michigan or under the trademark TAFMER™ available from MITSUI Chemicals Group of Minato Tokyo or under the trademark Nexlene™ from SK Chemicals.

[0058] The elastomers may be prepared using methods known in the art, for example by using a single site catalyst, i.e., a catalyst the transition metal components of which is an organometallic compound and at least one ligand of which has a cyclopentadienyl anion structure through which such ligand bondingly coordinates to the transition metal cation. This type of catalyst is also known as "metallocene" catalyst. Metallocene catalysts are for example described in U.S. Patent Nos. 5,017,714 and 5,324,820. The elastomer s may also be prepared using traditional types of heterogeneous multi-sited Ziegler-Natta catalysts.

[0059] Preferably, the elastomer has a melt flow index of 0.1 to 40 dg / min (ISO1133, 2.16kg, 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 of at least 2 dg / min, for example of at least 2.5 dg / min, for example of 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 in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 190 °C.

[0060] 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 may typically be at most 97.5 mol%, for example at most 95 mol% or at most 90 mol%.

[0061] In preferred embodiments, the thermoplastic polymer in the thermoplastic polymer composition is a propylene homopolymer.

[0062] In preferred embodiments, the thermoplastic polymer is a non-visbroken polypropylene, also known as a reactor grade. This results in better smell properties than visborken polypropylene made by visbreaking a reactor grade polypropylene with a lower melt flow index to increase its melt flow index.

[0063] Additives in of polymer sheath

[0064] The thermoplastic polymer composition of the polymer sheath may contain other usual additives, for instance nucleating agents and clarifiers, stabilizers, fillers, plasticizers, anti-oxidants, lubricants, antistatics, scratch resistance agents, impact modifiers, acid scavengers, recycling additives, coupling agents, anti-microbials, 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. The skilled person will know how to choose the type and amount of additives such that they do not detrimentally influence the aimed properties. The amount of the additives may e.g. be 0.1 to 50 wt% of the thermoplastic polymer composition, for example 0.1 to 25 wt% or 1.0 to 5.0 wt%.

[0065] In some preferred embodiments, the additives in the thermoplastic polymer composition of the polymer sheath comprises a coupling agent. Suitable examples of the coupling agent include a functionalized polyolefin grafted with an acid or acid anhydride functional group. 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- a-olefin copolymer consisting of at least 70 wt% of propylene and up to 30 wt% of a-olefin, for example ethylene, for example consisting of at least 80 wt% of propylene and up to 20 wt% of a-olefin, for example consisting of at least 90 wt% of propylene and up to 10 wt% of a-olefin, based on the total weight of the propylene- based matrix. Preferably, the a-olefin in the propylene- a-olefin copolymer is selected from the group of a-olefins having 2 or 4- 10 carbon atoms and is preferably ethylene. Examples of the acid or acid anhydride functional groups include (meth)acrylic acid and maleic anhydride. A particularly suitable material is for example maleic acid functionalized propylene homopolymer (for example Exxelor PO 1020 supplied by ExxonMobil and Fine-Blend® CMG5701 supplied by Fine-Blend Compatibilizer Jiangsu Co., Ltd). In particular maleic acid functionalized propylene homopolymer with low odor and TVOC is preferred, an example being Fine-Blend® CMG5701.

[0066] The amount of the coupling agent may e.g. be 0.5 to 3.0 wt%, preferably 1.0 to 2.0 wt%, based on the sheathed continuous multifilament strand.

[0067] Core

[0068] The sheathed continuous multifilament strand comprises a core that extends in the longitudinal direction. The core comprises an impregnated continuous multifilament strand comprising at least one continuous glass multifilament strand impregnating agent. The impregnated continuous multifilament strand is prepared from a continuous glass multifilament strand and an impregnating agent by impregnating the continuous glass multifilament strand with the impregnating agent.

[0069] Preferably, the at least one impregnated continuous multifilament strands 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%, for example at least 99wt% of the core. In a preferred embodiment, the core consists of the at least one impregnated continuous multifilament strand. In the context of the invention with ‘extends in the longitudinal direction’ is meant ‘oriented in the direction of the long axis of the sheathed continuous multifilament strand’.

[0070] Glass filaments of sheathed continuous multifilament strand of core

[0071] The continuous multifilament strand comprises glass filaments. Glass fibres are generally supplied as a plurality of continuous, very long filaments, and can be in the form of strands, rovings or yarns. A filament is an individual fibre of reinforcing material. A strand is a plurality of bundled filaments. Yarns are collections of strands, for example strands twisted together. A roving refers to a collection of strands wound into a package.

[0072] For purpose of the invention, a glass multifilament strand is defined as a plurality of bundled glass filaments.

[0073] Glass multifilament strands and their preparation are known in the art.

[0074] The filament density of the continuous glass multifilament strand may vary within wide limits. For example, the continuous glass multifilament strand may have a density of 1000 to 10000 grams per 1000 meter.

[0075] Preferably, the continuous glass multifilament strand has a density of 1000 to 2900 grams per 1000 meter, more preferably 1500 to 2800 grams per 1000 meter.

[0076] The continuous glass multifilament strand may have a filament diameter of 5 to 50 pm, more preferably from 10 to 30 pm, even more preferably from 15 to 25 pm. Usually the glass filaments are circular in cross section meaning the thickness as defined above would mean diameter. The glass filaments are generally circular in cross section.

[0077] Preferably, the ratio between the length of the glass fibers and the diameter of the glass fibers (L / D ratio) in the pellets is 500 to 1000.

[0078] The length of the glass filaments is in principle not limited as it is substantially equal to the length of the sheathed continuous multifilament strand. For practical reasons of being able to handle the strand however, it may be necessary to cut the sheathed continuous multifilament strand into a shorter strand. For example the length of the sheathed continuous multifilament strand is at least 1 m, for example at least 10 m, for example at least 50 m, for example at least 100m, for example at least 250 m, for example at least 500m and / or for example at most 25 km, for example at most 10km.

[0079] Preferably, the glass multifilament strand is coated with a sizing composition (i.e., a coating) to improve adhesion to the polymer matrix. The sizing composition can be disposed on substantially all of the glass filaments or on a portion of the glass filaments in the thermoplastic composition. The sizing provides coated glass filaments that can be either bonding or non-bonding towards the thermoplastic polymer composition of the sheath. Preferably, the coated glass filaments are bonding towards the polyester in the thermoplastic polymer composition of the sheath.

[0080] The sizing composition can include a polyepoxide, a poly(meth)acrylate, a poly(arylene ether), a polyurethane, or a combination thereof. The polyepoxide can be a phenolic epoxy resin, an epoxylated carboxylic acid derivative (e.g., a reaction product of an ester of a polycarboxylic acid having one or more unesterified carboxyl groups with a compound including more than one epoxy group), an epoxidized diene polymer, an epoxidized polyene polymer, or a combination thereof.

[0081] The sizing composition can further include a silane coupling agent to facilitate bonding with the glass fiber. The silane coupling agent can be tri(Ci.6alkoxy)mono amino silane, tri(Ci_6alkoxy)diamino silane, tri(Ci.6alkoxy)(Ci_6alkyl ureido) silane, tri(Ci.6alkoxy)(epoxy Ci_6alkyl) silane, tri(Ci_6alkoxy)(glycidoxy Ci_6alkyl) silane, tri(Ci_6alkoxy)(mercapto Ci_6alkyl) silane, or a combination thereof. For example, the silane coupling agent is (3 -aminopropyl)triethoxy silane, (3-glycidoxypropyl)trimethoxysilane, (2-(3,4- epoxycyclohexyl)ethyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3- (2- aminoethylamino)propyl)triethoxysilane, (3 -ureidopropyl)triethoxy silane, or a combination thereof. Preferably, the silane coupling agent is aminopropyltriethoxysilane, glycidylpropyltrimethoxysilane, or a combination thereof.

[0082] Other materials that can be included in the sizing composition include, but are not limited to, anti-static agents, coupling agents, lubricants, wetting agents, or the like. The sizing composition can be present in an amount from 0.1 to 5 wt% based on the weight of the at least one continuous glass multifilament strand. The sizing composition may be applied to the glass fibers by any means, such as immersing the glass multifilament strand in the sizing composition or contacting the glass multifilament strand with an aqueous emulsion, or suspension of the sizing composition. Other coating methods include using an aqueous dispersion of the sizing composition applied to the uncoated glass multifilament strand by a roller in a continuous fashion, which can be followed by a heat treatment or curing step.

[0083] Typically, after applying the sizing composition to the glass filaments, the filaments are bundled into the continuous glass multifilament strands and then wound onto bobbins to form a package.

[0084] Preferably, the amount of the at least one continuous glass multifilament strand is 10 to 70 wt%, for example 15 to 60 wt%, 20 to 50 wt% or 25 to 45 wt%, with respect to the sheathed continuous multifilament strand.

[0085] Impreqnatinq aqent

[0086] According to the invention, the core is prepared from a continuous glass multifilament strand and an impregnating agent. An impregnating agent in a molten state is applied to the continuous glass multifilament. Instead of conventionally used polyethylene wax, the impregnating agent according to the invention comprises a polypropylene.

[0087] In the present invention, the impregnating agent is preferably applied at a temperature of at least 190 °C, preferably 200 to 250 °C. Thus, for applying the impregnating agnet according to the invention, any method known in the art for applying conventional liquid impregnating agent like polyethylene wax may be used by adapting the application temperature.

[0088] The application of the impregnating agent may be performed using a die. Other suitable methods for applying the impregnating agent to the continuous multifilament strands include applicators having belts, rollers, and hot melt applicators. Methods for application of impregnating agent are for example described in documents EP0921919B1 , EP0994978B1 , EP0397505B1 , W02014 / 053590A1 and references cited therein, which can be applied to the present inveniton by adapting the application temperature. The method used should enable application of a constant amount of impregnating agent to the continuous multifilament strand.

[0089] The impregnating agent comprises a polypropylene and has a melt flow index as measured according to ISO1133-1 :2011 (2.16kg / 230°C) of preferably at least 3000 dg / min, preferably at least 3200 dg / min, at least 3500 dg / min or at least 3800 dg / min. This relatively high melt flow index allows the impregnating agent according to the invention in a molten state to be easily transferred to the equipments for their application. This also results in a good dispersion of the glass filaments in the molded article according to the invention.

[0090] The impregnating agent has a melting point of at least 140 °C, for example 145 to 155 °C, as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample.

[0091] The amount of the polypropylene in the impregnating agent is at least 80 wt%. Preferably, the amount of the polypropylene in the impregnating agent is at least 90wt%, 95wt%, at least 97wt% at least 98wt%, at least 99wt% or 100 wt%.

[0092] Preferably the polypropylene in the impregnating agent has a branching ratio of at most 5 %, preferably at most 3%, most preferably the polypropylene in the impregnating agent has a linear structure and free of branching.

[0093] Preferably, the polypropylene in the impregnating agent has a melt flow index as measured according to ISO1133-1 :2011 (2.16kg / 230°C) of at least 3000 dg / min preferably at least 3200 dg / min, at least 3500 dg / min or at least 3800 dg / min.

[0094] The polypropylene in the impregnating agent has an Mw of at most 5.5 kg / mol, preferably at most 5.0 kg / mol, preferably at least 3.0 kg / mol. Preferably, the polypropylene in the impregnating agent has a complex viscosity of at most 50 mPa.s, more preferably at most 40 mPa.s in a frenquency sweep of DMTA measurement at 10 rad / s, 200°C at 40 % strain.

[0095] Preferably, the polypropylene in the impregnating agent has a melting point of at least 140 °C, for example 145 to 155 °C, as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample.

[0096] Preferably, the polypropylene in the impregnating agent has an MWD (Mw / Mn) of at most 3.

[0097] Examples of suitable polypropylene is mG1 H40 available from Sinopec and Licocene PP 6102 from Clariant.

[0098] Preferably, the application of the impregnating agent is performed at a temperature of at least 190 °C, preferably 200 to 250 °C

[0099] Most preferably, the sheathed continuous multifilament strand is substantially free of a polyethylene wax having a melting point of 50 to 100 °C, MW of 5 to 10 kg / mol and a polydispersity index (MWD) of 5 to 10. In a less preferred embodiment, the sheathed continuous multifilament strand comprises a polyethylene wax having a melting point of 50 to 100 °C, MW of 5 to 10 kg / mol and a polydispersity index (MWD) of 5 to 10 in an amount of less than 3.0 wt%, less than 2.0 wt%, less than 1 .0 wt%, less than 0.50 wt%, 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%, with respect to the sheathed continuous multifilament strand. The melting point may be measured according to GB / T 19466.3- 2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample. An example of such a polyethylene wax is commercially available as Dicera 13082 Paramelt, which is a highly branched polyethylene wax.

[0100] In the embodiment that the sheathed continuous multifilament strand comprises a polyethylene wax, the polyethylene wax has MW of at most 10 kg / mol in an amount of less than 3.0 wt%, less than 2.0 wt%, less than 1 .0 wt%, less than 0.50 wt%, 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%, with respect to the sheathed continuous multifilament strand.

[0101] In the embodiment that the sheathed continuous multifilament strand comprises a polyethylene wax, the polyethylene wax has a melting point which is at least 20 °C lower than the polyolefin in the thermoplastic composition and a viscosity of from 2.5 to 100 cS determined 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) at 160°C in an amount of less than 3.0 wt%, less than 2.0 wt%, less than 1 .0 wt%, less than 0.50 wt%, 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%, with respect to the sheathed continuous multifilament strand.

[0102] In an embodiment the sheathed continuous multifilament strand comprises a microcrystalline polyethylene wax having at least one of the following properties in an amount of less than 3.0 wt%, less than 2.0 wt%, less than 1 .0 wt%, less than 0.50 wt%, 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%, with respect to the sheathed continuous multifilament strand: a drop melting point of from 60 to 90°C as determined in accordance with ASTM D127

[0103] - a congealing point of from 55 to 90°C as determined in accordance with ASTMD938

[0104] - a needle pen penetration at 25°C of from 7 to 40 tenths of a mm as determined in accordance with ASTM D1321

[0105] - a viscosity at 100°C of from 10 to 25mPa.s as determined in accordance with ASTM D445 and

[0106] - an oil content of from 0 to 5wt.% based on the weight of the microcrystalline wax as determined in accordance with ASTM D721.

[0107] Preferably, the core substantially consists of the continuous multifilament strand and the impregnating agent. Preferably, the continuous multifilament strand and the impregnating agent with respect to the core 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%. Further aspects

[0108] The pellets according to the invention are preferably prepared by a process comprising the sequential steps of a) unwinding from a package of the at least one continuous glass multifilament strand, b) applying the impregnating agent to the at least one continuous glass multifilament strand to form the impregnated continuous multifilament strand and c) applying the sheath of the thermoplastic polymer composition around the impregnated continuous multifilament strand to form the sheathed continuous multifilament strand and d) cutting the sheathed continuous glass multifilament strand into pellets.

[0109] Step d) may be followed by a step of moulding the pellets into (semi-)finished articles. Suitable examples of moulding processes include injection moulding, compression moulding, extrusion and extrusion compression moulding. Injection moulding is widely used to produce articles such as automotive exterior parts like bumpers and tailgates, automotive interior parts like instrument panels, or automotive parts under the bonnet. Housings for electronics and electrical appliances may also be made by injection moulding. Extrusion is widely used to produce articles such rods, sheets and pipes. The article may have a wall thickness of e.g. 0.1 to 10 mm.

[0110] Accordingly, the present invention further relates to a molded article comprising the glass fiber-reinforced thermoplastic polymer composition or the pellets according to the invention, wherein the article is selected from automotive exterior parts like bumpers and tailgates, automotive interior parts like instrument panels, automotive parts under the bonnet and housings for electronics and electrical appliances.

[0111] The present invention further relates to a process for making a molded article by molding the glass fiber-reinforced thermoplastic polymer composition or the pellets according to the invention, wherein the article is selected from automotive exterior parts like bumpers and tailgates, automotive interior parts like instrument panels, automotive parts under the bonnet and housings for electronics and electrical appliances.

[0112] It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.

[0113] It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product / composition comprising certain components also discloses a product / composition consisting of these components. The product / composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product / composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.

[0114] The invention is now elucidated by way of the following examples, without however being limited thereto.

[0115] Materials

[0116] SGF1 : chopped glass strands with silane sizing composition

[0117] LGF 1 : a glass roving having a diameter of 19 micron and a tex of 3000 (tex means grams glass per 1000m) containing a sizing composition comprising a silane coupling agent Wax1 : microcrystalline wax

[0118] Wax2: An ethylene based wax Dicera 13082 having an Mw of 6.4 kg / mol mPP1 : Polypropylene homopolymer with melt flow index of more than 4000 dg / min at 230°C and 2.16kg (test method: GB / T3682) and a melting point of 151 °C as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample; reactor grade

[0119] PP1 : SABIC PP 595E Polypropylene homopolymer with following properties: density: 905 kg / m3, melt flow index: 45 dg / min at 230°C and 2.16kg (test method: ISO1133); obtained by visbreaking of a polypropylene with a lower melt flow index using a peroxide and subsequent venting

[0120] PP2: SABIC PP M60T Polypropylene homopolymer with following properties: density: 905 kg / m3, melt flow index: 60 dg / min at 230°C and 2.16kg (test method: ISO1133); reactor grade

[0121] PP3: SABIC PP 591A Polypropylene homopolymer with following properties: density: 905 kg / m3, melt flow index: 6 dg / min at 230°C and 2.16kg (test method: ISO1133); reactor grade mPP2: Polypropylene homopolymer with melt flow index of 120 dg / min at 230°C and 2.16kg (test method: GB / T3682); reactor grade, mPP2 is a polypropylene in the impregnating agent according to the invention mPP3: Licocene PP6102 from Clariant having an Mw of 4.3 kg / mol.

[0122] P01020: 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 2.16kg (test method: ASTM D1238)

[0123] CMG5701 : polypropylene grafted with maleic anhydride from Fine-Blend Compatibilizer Jiangsu Co., Ltd.

[0124] A01010: antioxidant 1010 from BASF

[0125] AO168: antioxidant 168 from BASF

[0126] UV119: UV stabilizer UV 119 from SABO SpA

[0127] Tinuvin 622: UV stabilizer

[0128] CMB: black color masterbatch

[0129] Experiment set 1 (reference)

[0130] The components shown in Table 1 were melt-mixed and properties of the obtained compositions were determined.

[0131] Tensile performance was tested after 7 days at 23 °C aging according to ISO527.

[0132] Flexural performance was tested after 7 days at 23 °C aging according to ISO178.

[0133] Table 1

[0134] The use of mPP1 instead of Wax1 resulted in an increase in the tensile modulus and strength and flexural modulus and strength while maintaining or improving the smell properties.

[0135] Comparison of RE1-RE4 vs RE5-RE8 shows that the use of the reactor grade PP resulted in better smell properties than the use of visbroken PP.

[0136] Experiment set 2 Table 2

[0137] Pellets of sheathed continuous multifilament strands are prepared using components given in Table 2 using the wire coating process as described in detail in the examples of W02009 / 080281A1.

[0138] Wax1 or mPP1 is applied to LGF1 at a temperature of at least 190 °C to obtain an impregnated continuous glass multifilament.

[0139] Polypropylene and additives shown in table 2 are fed to an extruder to sheath the impregnated continuous glass multifilament using an extruder-head wire-coating die. The sheathing step is performed in-line directly after the impregnating step. The obtained sheathed continuous multifilament strand is cut into pellets having length of 8-15 mm and diameter of 3-4 mm. The obtained pellets are molded using ARBURG 320T injection molding machine to prepare the samples for testing.

[0140] Same trends in the properties are noted as in the reference examples: The use of mPP1 instead of Wax1 results in an increase in the tensile modulus and strength and flexural modulus and strength and satisfactory smell properties.

[0141] Experiment set 3

[0142] In a frenquency sweep of DMTA measurement at 10 rad / s, 200°C at 40 % strain, Wax 2 has a complex viscosity of 10 mPa.s, while mPP3 has a complex viscosity of 35 mPa.s.

[0143] Table 3

[0144]

[0145] The samples in Table 3 was prepared in the same process as Table 2.

Claims

CLAIMS1 . A glass fiber-reinforced thermoplastic polymer composition comprising a sheathed continuous multifilament strand comprising a core that extends in the longitudinal direction and a polymer sheath which intimately surrounds said core, wherein the core comprises an impregnated continuous multifilament strand comprising at least one continuous glass multifilament strand, wherein the at least one continuous glass multifilament strand is impregnated with an impregnating agent comprising a polypropylene, wherein the polypropylene in the impregnating agent has an Mw of at most 5.5 kg / mol and a melting point of at least 140 °C as measured according to GB / T 19466.3-2004 at a melting temperature increase rate of 20 °C / min using 5 mg sample and the amount of the polypropylene in the impregnating agent is at least 80% with respect to the impregnating agent, wherein the polymer sheath consists of a thermoplastic polymer composition comprising a thermoplastic polymer.

2. The glass fiber-reinforced thermoplastic polymer composition according to claim 1 , wherein the sheathed continuous multifilament strand comprises a polyethylene wax having a melting point of 50 to 100 °C, MW of 5 to 10 kg / mol and a MWD of 5 to 10 in an amount of less than 3.0 wt%, less than 2.0 wt%, less than 1 .0 wt%, 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%, with respect to the sheathed continuous multifilament strand.

3. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the polypropylene in the impregnating agent has a melt flow index as measured according to ISO1133-1 :2011 (2.16kg / 230°C) of at least 3000 dg / min and / or a MWD of at most 3.

4. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the amount of the impregnating agent with respect to the sheathed continuous multifilament strand is 1 .0 to 5.0 wt%.

5. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the thermoplastic polymer has a melt flow index in the range from 20 to 150 dg / min, for example in the range from 30 to 140 dg / min as measured according to ISO1133-1 :2011 (2.16kg / 230°C).

6. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the amount of the thermoplastic polymer with respect to the thermoplastic polymer composition is at least 80 wt%, for example at least 90wt%, at least 93wt%, at least 95wt%, at least 97wt% at least 98wt% or at least 99wt%.

7. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the thermoplastic polymer is a polyolefin, preferably wherein the polyolefin is chosen from the group of polypropylenes or elastomers of ethylene and a-olefin comonomer having 4 to 8 carbon atoms, and any mixtures thereof.

8. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the thermoplastic polymer is a polypropylene.

9. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the thermoplastic polymer is a non-visbroken polypropylene.

10. The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the thermoplastic polymer composition of the polymer sheath comprises a maleic acid functionalized propylene homopolymer.11 . The glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims, wherein the amount of the impregnated continuous multifilament strand is 10 to 80 wt%, for example 10 to 50 wt% (for example 25 to 45 wt%) or 50 to 80 wt% (for example 60 to 75 wt%), with respect to the sheathed continuous multifilament strand.

12. Pellets comprising the glass fiber-reinforced thermoplastic polymer composition according to any one of the preceding claims.

13. A process for preparing the glass fiber-reinforced thermoplastic polymer composition according to any one of claims 1-11 , comprising the sequential steps of: a) unwinding from a package of the at least one continuous glass multifilament strand, b) applying the impregnating agent to the at least one continuous glass multifilament strand to form the impregnated continuous multifilament strand and c) applying the 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 strand into pellets.

14. The process according to claim 13, wherein step b) is performed at a temperature of at least 190 °C, preferably 200 to 250 °C.

15. A molded article comprising the glass fiber-reinforced thermoplastic polymer composition according to any one of claims 1-11 or the pellets of claim 12.

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