Processes for improving the utility of recycled polypropylene

Abstract

The present invention relates to a process for producing a glass fiber reinforced composition containing recycled polypropylene. The present invention further relates to the glass fiber reinforced composition obtained by said process.

Description

[Technical field]

[0001] The present invention relates to a process for the manufacture of a glass fiber reinforced composition comprising recycled polypropylene. The present invention further relates to a glass fiber reinforced composition obtained by the process. [Background technology]

[0002] Polypropylene recycling processes are known to those skilled in the art, for example, polypropylene recycling processes such as those described in WO 2012117250, US 9670344, WO 2014040634, etc. However, recycled polypropylene usually has reduced mechanical properties such as tensile modulus compared to virgin polypropylene. One typical solution to this problem is to dilute recycled polypropylene with virgin polypropylene to obtain a polypropylene blend, but polypropylene blends are also usually subject to the degradation of recycled polypropylene.

[0003] Therefore, there is a need in the industry to improve the utility of recycled polypropylene, for example, to have a process for using recycled polypropylene without compromising mechanical properties such as tensile modulus. Summary of the Invention

[0004] This need is met by a process for making a glass fiber reinforced composition comprising the following successive steps: a) A continuous glass multifilament strand is unwound from a package. b) applying an impregnating agent to the continuous glass multifilament strand to form an impregnated continuous multifilament strand; c) applying a sheath of a first polymer composition around the impregnated continuous multifilament strand to form a sheathed continuous multifilament strand. d) pelletizing the sheathed continuous multifilament strands to form pellets of sheathed multifilament strands. e) homogenizing the pellets of sheathed multifilament strands with a second polymer composition;

[0005] the first polymer composition comprises recycled polypropylene (PP1), the amount of recycled polypropylene (PP1) being at least 80 wt.-% based on the total amount of the first polymer composition; the second polymer composition comprises a second polypropylene (PP2), the amount of the second polymer composition (PP2) being at least 80 wt.-%, based on the total amount of the second polymer composition; The melt flow index (MFI) of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula.

number

[0006] The inventors have surprisingly discovered that the process according to the invention can improve the utility of recycled polypropylene since no loss in tensile modulus is observed.

[0007] Steps a) and b) are described in detail in WO 2009 / 080281 A1, which document is incorporated herein by reference. Step c) is also disclosed in WO 2009 / 080281 A1, except for the first polymer composition.

[0008] Preferably, step b) is carried out in a first extruder, the impregnating agent being fed to the first extruder and the continuous glass multifilament strands being preferably drawn from the barrel of the first extruder through a die disposed on the side of the barrel.

[0009] Preferably, step c) is carried out in a second extruder, the first polymer composition being fed to the second extruder and the impregnated continuous multifilament strands being preferably drawn through the barrel of the second extruder through a die disposed in the side of the barrel.

[0010] Preferably, in the sheathed continuous multifilament strand obtained in step c), the impregnating agent intimately surrounds the continuous glass multifilament strand and the sheath of the first polymer composition intimately surrounds the impregnated continuous multifilament strand.

[0011] The term "closely surrounding" as used herein is understood to mean that the impregnating agent is in substantially complete contact with the continuous multifilament glass strand and that the coating of the first polymer composition is in substantially complete contact with the impregnated continuous multifilament strand.

[0012] In other words, the sheath of the first polymer composition is applied to the impregnated continuous multifilament strand such that there are no intentional gaps between the inner surface of the sheath of the first polymer composition and the impregnated continuous multifilament strand. Nevertheless, those skilled in the art will appreciate that some small gaps may form between the sheath of the first polymer composition and the impregnated continuous multifilament strand as a result of process variations. Thus, preferably, the sheath of the first polymer composition comprises less than 5% by weight of the filaments, preferably less than 2% by weight, based on the total weight of the polymer sheath.

[0013] Preferably, step d) comprises two successive steps. d1) The sheathed continuous multifilament strand is cooled, for example, using an air blade or a water bath (preferably a water bath). d2) cutting the cooled sheathed continuous multifilament strand into pellets of sheathed multifilament strands, the pellets typically being cylindrical in shape and having a length in the range of 4-25 mm, preferably 10-20 mm.

[0014] Preferably, step e) is carried out by dry blending pellets of the sheathed multifilament strands with the second polymer composition or by melt mixing pellets of the sheathed multifilament strands with the second polymer composition, dry blending being understood as mixing the pellets without the need for heating, whereas melt mixing requires heating to melt and further mix the pellets.

[0015] More preferably, step e) is carried out by dry blending pellets of the sheathed multifilament strands with the second polymer composition.

[0016] The impregnated continuous multifilament strand comprises a continuous glass multifilament strand and an impregnating agent.

[0017] Glass fibers are usually supplied as multiple continuous very long filaments and can be in the form of strands, rovings, or yarns. A filament is an individual fiber of reinforcement. A strand is multiple bundled filaments. A yarn is an assembly of strands, e.g., strands twisted together. A roving refers to an assembly of strands wound into a package.

[0018] For purposes of this invention, a multifilament glass strand is defined as a plurality of bundled glass filaments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Multifilament glass strands and their manufacture are known in the art.

[0020] The filament density of the continuous multifilament glass strand may vary within wide limits. For example, the continuous multifilament glass strand may have at least 500, such as at least 1000, glass filaments / strand and / or up to 10000, such as up to 5000 grams of glass filaments / strand per 1000 meters. Preferably, the amount of glass filaments / strand is in the range of 500 to 10000 grams of glass filaments / strand per 1000 meters of glass filaments / strand.

[0021] The thickness of the glass filament is preferably in the range of 5 to 50 μm, more preferably 10 to 30 μm, and further preferably 15 to 25 μm. Usually, the glass filament has a circular cross section, which means that the thickness defined above means the diameter. The glass filament generally has a circular cross section.

[0022] The length of the glass filaments is not limited, since in principle it is substantially equal to the length of the sheathed continuous multifilament strand. However, for practical reasons to be able to handle the tape, it may be necessary to cut the sheathed continuous multifilament strand into shorter strands. For example, the length of the sheathed continuous multifilament strand is at least 1 m, such as at least 10 m, such as at least 50 m, such as at least 100 m, such as at least 250 m, such as at least 500 m, and / or for example up to 25 km, such as up to 10 km.

[0023] Preferably, the continuous multifilament glass strands in the tape of the invention comprise a sizing agent in an amount of up to 2% by weight, preferably in the range of 0.10 to 1% by weight, based on the continuous multifilament glass strand. The amount of sizing can be determined using ISO 1887:2014.

[0024] The sizing composition is typically applied to the glass filaments before they are bundled into continuous glass multifilament strands.

[0025] Suitable examples of sizing compositions include solvent-based compositions, such as organic materials dissolved in an aqueous solution or dispersed in water, and melt- or radiation-cured based compositions. Preferably, the sizing composition is an aqueous sizing composition.

[0026] As described in the art, for example in documents EP 1 460 166 A1, EP 0 206 189 A1 or US 4 338 233, the aqueous sizing composition may contain film formers, coupling agents and other additional ingredients.

[0027] The film former is usually present in an amount effective to protect the fiber from interfilament abrasion and to provide fiber strand integrity and processability after drying. Suitable film formers are miscible with the polymer being reinforced. For example, to reinforce polypropylene, suitable film formers generally include polyolefin waxes.

[0028] Coupling agents are generally used to improve adhesion between the matrix thermoplastic polymer and the fiber reinforcement. Suitable examples of coupling agents known in the art to be used with glass fibers include organofunctional silanes. More specifically, the coupling agents added to the sizing composition are aminosilanes, such as aminomethyltrimethoxysilane, N-(beta-aminoethyl)-gamma-aminopropyl-trimethoxysilane, gamma-aminopropyl-trimethoxysilane, gamma-methylaminopropyl-trimethoxysilane, delta-aminobutyl-triethoxysilane, 1,4-aminophenyl-trimethoxysilane. Preferably, in the tapes of the present invention, the sizing composition includes aminosilanes to enable good adhesion to the thermoplastic matrix. The sizing composition may further include any other additional components known to those skilled in the art to be suitable for a sizing composition. Suitable examples include, but are not limited to, lubricants (used to prevent damage to the strands due to abrasion), antistatic agents, crosslinking agents, plasticizers, surfactants, nucleating agents, antioxidants, pigments, and mixtures thereof.

[0029] Typically, after the sizing composition is applied to the glass filaments, the filaments are bundled into continuous glass multifilament strands and then wound onto bobbins to form a package.

[0030] In the present invention, the impregnated continuous multifilament strand is produced from a continuous glass multifilament strand and an impregnating agent, in particular by applying the impregnating agent to the continuous glass multifilament strand, preferably in an amount of 0.50 to 18.0% by weight, for example 0.5 to 10.0% by weight, or for example 10.0 to 18.0% by weight, based on the sheathed continuous multifilament strand.

[0031] The optimum amount of impregnating agent applied to the continuous multifilament glass strand depends on the sheath of the first polymer composition, the size (diameter) of the glass filaments forming the continuous glass strand, and the type of sizing composition. Typically, the amount of impregnating agent applied to the continuous multifilament glass strand is, for example, at least 0.50% by weight, preferably at least 1.0% by weight, preferably at least 1.5% by weight, preferably at least 2% by weight, preferably at least 2.5% by weight, and / or up to 10.0% by weight, preferably up to 9.0% by weight, more preferably up to 8.0% by weight, even more preferably up to 7.0% by weight, even more preferably up to 6.0% by weight, even more preferably up to 5.5% by weight, or for example at least 10.0% by weight, preferably at least 11% by weight, preferably at least 12% by weight, and / or up to 18% by weight, preferably up to 16% by weight, preferably up to 14% by weight, based on the amount of the sheathed continuous multifilament strand. Preferably, the amount of impregnating agent is in the range of 1.5-8 wt.%, more preferably 2.5-6.0 wt.%, based on the coated continuous multifilament strand. The higher the amount of impregnating agent, the higher the impact energy per unit thickness (J / mm). However, for reasons of cost-effectiveness, low emissions (volatile organic compounds) and mechanical properties, the amount of impregnating agent should not be too high.

[0032] For example, the ratio of the impregnating agent to the continuous glass multifilament strands is in the range of 1:4 to 1:30, preferably in the range of 1:5 to 1:20.

[0033] Preferably, the viscosity of the impregnating agent is in the range of 2.5 to 200 cSt at 160°C, more preferably at least 5.0 cSt, even more preferably at least 7.0 cSt, and / or up to 150.0 cSt at 160°C, preferably up to 125.0 cSt, preferably up to 100.0 cSt.

[0034] Impregnating agents with a viscosity higher than 100 cSt are difficult to apply to continuous glass multifilament strands. Although low viscosity is necessary to promote good wetting of the fibers, impregnating agents with a viscosity less than 2.5 cSt are difficult to handle, e.g., the amount applied is difficult to control and the impregnating agent may volatilize. For the purposes of this invention, unless otherwise specified, the viscosity of the impregnating agent is measured at 160 ° C according to ASTM D 3236-15 (Standard Test Method for Apparent Viscosity of Hot Melt Adhesive and Coating Materials, Brookfield Viscometer Model RVDV 2, #27 spindle, 5 r / min).

[0035] Preferably, the melting point of the impregnating agent (the lowest melting point in the melting point range) is at least 20° C. lower than the melting point of the first polymer composition. More preferably, the impregnating agent has a melting point at least 25 or 30° C. lower than the melting point of the first polymer composition. For example, if the melting point of the first polymer composition is about 160° C., the melting point of the impregnating agent may be at most about 140° C.

[0036] Suitable impregnating agents may be compatible with the thermoplastic polymer to be reinforced and soluble in the polymer. A person skilled in the art can select a suitable combination based on his general knowledge, and can also find such combinations in the art.

[0037] The impregnating agent preferably comprises a highly branched poly(alphaolefin), such as highly branched polyethylene, a modified low molecular weight polypropylene, a mineral oil, such as paraffin or silicone, and any mixture of these compounds.

[0038] The impregnating agent preferably comprises at least 20% by weight, more preferably at least 30% by weight, more preferably at least 50% by weight, such as at least 99.5% by weight, for example 100% by weight, of branched poly(alphaolefin), most preferably branched polyethylene.

[0039] In order for the impregnating agent to reach a viscosity of 2.5 to 200 cSt at 160° C., the branched poly(alpha olefin) can be mixed with an oil, the oil being selected from the group consisting of mineral oils, such as paraffin oil or silicon oil, hydrocarbon oils, and any mixtures thereof.

[0040] Preferably, the impregnating agent is non-volatile and / or substantially solvent-free. In the context of the present invention, non-volatile means that the impregnating agent has a boiling point or range higher than the temperature at which it is applied to the continuous multifilament glass strand. In the present invention, "substantially solvent-free" means that the impregnating agent contains less than 10% solvent by weight, preferably less than 5% solvent by weight, based on the impregnating agent. In a preferred embodiment, the impregnating agent does not contain organic solvents.

[0041] The impregnating agent may further be mixed with other additives known in the art. Suitable examples include lubricants, antistatic agents, UV stabilizers, plasticizers, surfactants, nucleating agents, antioxidants, pigments, dyes, and adhesion promoters such as modified polypropylene with maleic acid reactive groups, and any combination thereof, as long as the viscosity remains within the desired range. Any method known in the art can be used to apply the liquid impregnating agent to the continuous glass multifilament strand. The application of the liquid impregnating agent may be carried out using a die. Other suitable methods for applying the impregnating agent to the continuous multifilament strand include application devices with belts, rollers, and hot melt application devices. Such methods are described, for example, in documents EP 0921919 B1, EP 0994978 B1, EP 0397505 B1, WO 2014 / 053590 A1 and references cited therein. The method used should allow for the application of a consistent amount of impregnation agent to the continuous multifilament strand.

[0042] Preferably, the amount of glass multifilament strands is in the range of 15-50% by weight, more preferably 17-35% by weight, even more preferably 18-25% by weight, based on the total amount of the glass fiber reinforced composition obtained in step e).

[0043] A sheath of the first polymer composition

[0044] Preferably, the thickness of the sheath of the first polymer composition in the sheathed continuous multifilament strand is 200 to 1500 micrometers, for example 500 to 1500 micrometers.

[0045] Preferably, the amount of the first polymer composition is in the range of 6 to 35% by weight, more preferably 8 to 25% by weight, even more preferably 9 to 16% by weight, based on the total amount of the glass fiber reinforced composition obtained in step e).

[0046] The first polymer composition comprises recycled polypropylene (PP1), the amount of recycled polypropylene (PP1) being at least 80% by weight, preferably at least 90% by weight, preferably at least 94% by weight, based on the total amount of the first polymer composition.

[0047] The recycled polypropylene (PP1) used in the present invention is obtained by treating post-consumer and / or post-industrial, preferably post-industrial origin, waste plastic material by known methods, including for example washing, sorting and / or crushing.

[0048] The recycled polypropylene (PP1) preferably comprises a propylene-based polymer in an amount of at least 90% by weight relative to the recycled composition, where propylene-based polymer is understood to be a propylene homopolymer, a propylene copolymer, including a random copolymer and a (multi)block copolymer, or a heterophasic propylene copolymer having propylene monomer units in an amount of at least 50% by weight, for example at least 80% by weight.

[0049] The recycled polypropylene (PP1) preferably has an ash residue of less than 5.0 wt%, preferably less than 3.0 wt%, more preferably less than 2.0 wt%, based on the total amount of recycled polypropylene (PP1), measured at 550°C. A low ash content may improve aesthetics and allow better control of the amount of inorganic material in the blend composition of the present invention. Without wishing to be bound by any theory, the ash residue in the recycled polypropylene (PP1) is preferably at least 0.5 wt%, more preferably at least 1.0 wt%, which leads to complex crystallization and improves the stiffness of the glass fiber reinforced composition obtained in step e).

[0050] Preferably, the MFI of the recycled polypropylene (PP1) is in the range of 15 to 60 g / 10 min, preferably 18 to 45 g / 10 min, more preferably 19 to 30 g / 10 min, measured according to ISO1133-1:2011 at 230° and 2.16 kg.

[0051] Preferably, the recycled polypropylene (PP1) has a tensile modulus in the range of 1050 to 1800 MPa, preferably 1100 to 1570 MPa, more preferably 1125 to 1325 MPa, when measured according to ISO 527-1:2019 using a 1A test piece.

[0052] The first polymer composition according to the invention may further comprise additives such as nucleating and clarifying agents, stabilizers, release agents, plasticizers, antioxidants, lubricants, antistatic agents, crosslinking agents, scratch resistant agents, high performance fillers, pigments and / or colorants, flame retardants, foaming agents, acid scavengers, recycling additives, antimicrobial agents, anti-fog additives, slip additives, anti-blocking additives, polymer processing aids, etc. Such additives are well known in the art. The total amount of recycled polypropylene (PP1) and additives is preferably at least 95% by weight, more preferably at least 98% by weight, based on the total amount of the first polymer composition.

[0053] Second Polymer Composition

[0054] The second polymer composition comprises a second polypropylene (PP2), the amount of the second polypropylene (PP2) being at least 80% by weight, preferably at least 90% by weight, more preferably at least 95% by weight, even more preferably at least 98% by weight, based on the total amount of the second polymer composition.

[0055] The second polymer composition is preferably provided in step e) in the form of pellets.

[0056] The amount of the second polymer composition is preferably in the range of 30-80% by weight, preferably 40-75% by weight, more preferably 50-72% by weight, based on the total amount of the glass fiber reinforced composition obtained in step e).

[0057] The second polypropylene (PP2) is preferably virgin polypropylene, where "virgin" means that the second polypropylene (PP2) has not been molded or used prior to being used in step e).

[0058] The second polypropylene (PP2) is preferably a heterophasic polypropylene comprising a propylene homopolymer as the matrix and an ethylene-α-olefin copolymer as the dispersed phase, the amount of propylene homopolymer being preferably in the range of 74-88 wt%, more preferably 80-87 wt%, based on the total amount of the heterophasic polypropylene. The total amount of propylene homopolymer and ethylene-α-olefin copolymer is preferably at least 95 wt%, more preferably at least 98 wt%, even more preferably at least 95 wt%, based on the total amount of the heterophasic polypropylene. The amount of propylene-based matrix and dispersed ethylene-α-olefin copolymer can be determined by the following formula, as is well known in the art: 13 The molecular weight distribution can be determined by C-NMR. Preferably, the ethylene-α-olefin copolymer is an ethylene-propylene copolymer.

[0059] The heterophasic polypropylene used in the present invention can be produced using any conventional technique known to those skilled in the art, for example, multi-stage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization, or any combination thereof. Any conventional heterogeneous catalyst system can be used, for example, Ziegler-Natta or metallocene. Such techniques and catalysts are described, for example, in WO 06 / 010414, Polypropylene and other Polyolefins, by Ser van der Ven, Studies in Polymer Science 7, Elsevier 1990, WO 06 / 010414, U.S. Pat. No. 4,399,054, and U.S. Pat. No. 4,472,524.

[0060] Preferably, the heterophasic polypropylene is produced using a Ziegler-Natta catalyst. Heterophasic polypropylene is - polymerizing propylene and optionally ethylene and / or α-olefins in the presence of a catalytic system to obtain a propylene-based matrix; - followed by polymerization of ethylene and an α-olefin in a propylene-based matrix in the presence of a catalytic system to obtain a dispersed ethylene-α-olefin copolymer. These steps are preferably carried out in different reactors. The catalytic systems of the first and second steps can be different or the same.

[0061] The tensile modulus of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula.

number

[0062] Preferably, the tensile modulus of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula:

number

[0063] The melt flow index (MFI) of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula.

number

[0064] Preferably, the melt flow index (MFI) of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula:

number

[0065] Preferably, the melt flow index (MFI) of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula:

number

[0066] Without wishing to be bound by theory, the MFI ratio in the preferred range may facilitate the dispersion of the recycled polypropylene (PP1) in the second polypropylene (PP2) during step e) and / or during further molding processes, such as injection molding.

[0067] Preferably, in the glass fiber reinforced composition obtained in step e), the ratio between the amount of the first polymer composition and the amount of the second polymer composition is in the range of 0.09 to 0.32, more preferably 0.12 to 0.23, even more preferably 0.14 to 0.21.

[0068] The invention further relates to a process for the manufacture of an article comprising a process for the manufacture of a glass fiber reinforced composition according to the invention and a step of injection molding the glass fiber reinforced composition obtained in step e) to obtain an article, preferably an automotive part.

[0069] The present invention further relates to a glass fiber reinforced composition obtainable by the process for producing a glass fiber reinforced composition according to the invention.The present invention further relates to an article comprising the glass fiber reinforced composition, said article being preferably an automotive part.

[0070] The present invention further relates to the use of the process for producing a glass fiber reinforced composition according to the present invention to improve the utility of recycled polypropylene.

[0071] Experimental Example material Virgin PP1: SABIC PP 513MNK10E Virgin PP2: SABIC PP 612MK10EE PCR1: Recycled polypropylene, Moprilen PC B-420 from Morsikhov-Lymoplast PCR2: Recycled polypropylene, Moprilen PC B-430 from Morsikhov-Lymoplast Wax: Dicera 13082 Paramelt is the impregnating agent according to the invention. GF: A glass multifilament strand GF having a diameter D of 19 microns and a tex of 3000, containing 2% by mass of an aminosilane sizing agent, was continuously provided. Additive package: 20 wt. % antioxidant B225, 75 wt. % coupling agent PO1020, 5 wt. % ultraviolet stabilizer UV119. Weight percentages are based on total weight of additive package. The properties of virgin PP1, virgin PP2, PCR1 and PCR2 are shown in Table 1.

[0072] [Table 1]

[0073] Table 1 Properties of virgin PP1, virgin PP2, PCR1, and PCR2 Measurement norms are also shown in Table 1.

[0074] Comparison Process Virgin PP1, virgin PP2, PCR1, and PCR2 were mixed in a twin-screw extruder, and the samples obtained from the mixing process were injection molded and subjected to tensile measurements according to ISO527-1:2019 using 1A test specimens.

[0075] The compositions and tensile moduli of elasticity of Experimental Examples 1 to 3 are shown in Table 2.

[0076] [Table 2]

[0077] Table 2 Composition and tensile modulus of Experimental Examples 1 to 3 Comparing Examples 1 to 3, it is clear that after being manufactured by the comparative process, Ex2 and 3 containing PCR are less stiff than Ex1 containing virgin PP1.

[0078] Examples 4, 5, and 6 were prepared by a process involving the following sequence of steps. a) The continuous GF is unwound from the package. b) Wax is applied to the GF to form an impregnated GF. c) A thermoplastic composition consisting of virgin PP1 or PCR1 or PCR2 and an additive package is applied as a sheath around the impregnated GF to form a sheath GF. d) Pelletizing the sheath GF. e) Dry mix the pelletized sheath GF with virgin PP2. The examples obtained in step e) were injection molded for tensile measurements according to ISO527-1:2019 using 1A specimens.

[0079] The compositions of Experimental Examples 4 to 6 are shown in Table 3.

[0080] [Table 3]

[0081] Table 3 Composition and tensile modulus of Experimental Examples 4 to 6 Comparing Examples 4-6, it is clear that Examples 5 and 6 containing PCR are surprisingly stiffer when produced by the process of the present invention than Example 4 containing virgin PP1. The information in Table 3 shows that the process of the present invention improves the utility of recycled polypropylene.

Claims

1. 1. A process for producing a glass fiber reinforced composition comprising: a) unwinding a continuous glass multifilament strand from a package; b) applying an impregnating agent to the continuous glass multifilament strand to form an impregnated continuous multifilament strand; c) applying a sheath of a first polymer composition around said impregnated continuous multifilament strand to form a sheathed continuous multifilament strand; d) pelletizing the sheathed continuous multifilament strand to form pellets of the sheathed multifilament strand; e) homogenizing said pellets of sheathed multifilament strands with a second polymer composition; the first polymer composition comprises recycled polypropylene (PP1), the amount of the recycled polypropylene (PP1) being at least 80 wt.% based on the total amount of the first polymer composition; said second polymer composition comprising a second polypropylene (PP2), the amount of said second polymer composition (PP2) being at least 80 wt.% based on the total amount of said second polymer composition; A manufacturing process, wherein the melt flow index (MFI) of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula: [0010] (Here, MFI ＰＰ１ is the MFI of recycled polypropylene (PP1) measured at 230° and 2.16 kg according to ISO 1133-1:2011, and MFI ＰＰ２ is the MFI of the second polypropylene (PP2) measured at 230° and 2.16 kg according to ISO 1133-1:2011.

2. 2. The process of claim 1, wherein the tensile modulus of the recycled polypropylene (PP1) and the second polypropylene (PP2) satisfies the following formula: [0025] (Here, T.M. ＰＰ１ is the tensile modulus of the recycled polypropylene (PP1) measured according to ISO 527-1: 2019 using a 1A test piece, and TM ＰＰ２ is the MFI of the second polypropylene (PP2) measured according to ISO 527-1:2019 using a 1A test specimen.

3. 3. The process according to claim 1 or 2, wherein the recycled polypropylene (PP1) has an ash residual of less than 5.0 wt.%, preferably less than 3.0 wt.%, more preferably less than 2.0 wt.%, measured according to ISO 3451-1:2019 at 550°C, based on the total amount of the recycled polypropylene (PP1).

4. 20. The process according to any one of the preceding claims, wherein the recycled polypropylene (PP1) has an MFI of 15-60 g / 10min, preferably 18-45 g / 10min, more preferably 19-30 g / 10min, measured according to ISO 1133-1:2011 at 230° and 2.16 kg.

5. 20. The process according to any one of the preceding claims, wherein the recycled polypropylene (PP1) has a tensile modulus of 1050-1800 mpa, preferably 1100-1570 mpa, more preferably 1125-1325 mpa, measured according to ISO 527-1:2019 using a 1A test specimen.

6. The step d) comprises: d1) cooling the sheathed continuous multifilament strand, preferably using a water bath; d2) cutting the cooled sheathed continuous multifilament strand into pellets of sheathed multifilament strands.

7. 10. The process according to any one of the preceding claims, wherein the pellet of sheathed multifilament strands is cylindrical and the length of the pellet ranges from 4 to 25 mm, preferably from 10 to 20 mm.

8. 13. The process of any one of the preceding claims, wherein said step e) is carried out by dry blending said sheathed multifilament strand pellets with said second polymer composition or by melt mixing said sheathed multifilament strand pellets with said second polymer composition.

9. 2. The process of any one of the preceding claims, wherein step b) is carried out in a first extruder.

10. 2. The process of any one of the preceding claims, wherein step c) is carried out in a second extruder.

11. 10. A process for manufacturing an article, comprising the process according to any one of the preceding claims and a step of injection moulding the glass fibre reinforced composition obtained in step e) to obtain an article.

12. The process of claim 11 , wherein the article is an automotive part.

13. A glass fibre reinforced composition obtainable by the process according to any one of claims 1 to 10.

14. 14. An article comprising the glass fiber reinforced composition of claim 13, preferably an automotive part.

15. Use of the process according to any one of claims 1 to 10 to improve the utility of recycled polypropylene.

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